First-principles modeling of hardness in transition-metal diborides

NASA Astrophysics Data System (ADS)

Lazar, Petr; Chen, Xing-Qiu; Podloucky, Raimund

2009-07-01

Based on recent experiments, the diborides OsB2 and ReB2 were proposed to be ultraincompressible and superhard materials. By application of an ab initio density-functional theory approach we investigate the elastic and cleavage fracture properties of the borides MB2 ( M=Hf , Ta, W, Re, Os, and Ir). We derive a direct correlation between the lowest calculated critical cleavage stress and the experimental (micro)hardness. By calculating the critical shear stress and estimating the possibility of dislocation emission we can justify the prediction that ReB2 is indeed a superhard material.

Method for ultra-fast boriding

DOEpatents

Erdemir, Ali; Sista, Vivekanand; Kahvecioglu, Ozgenur; Eryilmaz, Osman Levent

2017-01-31

An article of manufacture and method of forming a borided material. An electrochemical cell is used to process a substrate to deposit a plurality of borided layers on the substrate. The plurality of layers are co-deposited such that a refractory metal boride layer is disposed on a substrate and a rare earth metal boride conforming layer is disposed on the refractory metal boride layer.

Fabrication and Characterization of Plasma Electrolytic Borocarburized Layers on Q235 Low-Carbon Steel at Different Discharge Voltages

NASA Astrophysics Data System (ADS)

Wang, Bin; Wu, Jie; Jin, Xiaoyue; Wu, Xiaoling; Wu, Zhenglong; Xue, Wenbin

The influence of applied voltage on the plasma electrolytic borocarburizing (PEB/C) layer of Q235 low-carbon steel in high-concentration borax solution was investigated. XRD and XPS spectra of PEB/C layer confirmed that the modified boride layer mainly consisted of Fe2B phase, and the FeB phase only exists in the loose top layer. The applied voltage on Q235 steel played a key role in determining the properties of hardened layers. The thickness and microhardness of boride layers increased with the increase of the applied voltage, which led to superior corrosion and wear resistances of Q235 low-carbon steel. The diffusion coefficient (D) of boride layer at 280, 300 and 330V increased with borocarburizing temperature and ranged from 0.062×10-12m2/s to 0.462×10-12m2/s. The activation energy (Q) of boride layer growth during PEB/C treatment was only 52.83kJṡmol-1, which was much lower than that of the conventional boriding process.

Boriding of high carbon high chromium cold work tool steel

NASA Astrophysics Data System (ADS)

Muhammad, W.

2014-06-01

High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30% B4C, 70% borax at 950 °C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 μm. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc wer test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time.

Niobium boride layers deposition on the surface AISI D2 steel by a duplex treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kon, O., E-mail: okon42@htotmail.com; Pazarlioglu, S.; Sen, S.

2015-03-30

In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000{sup o}C for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950°C using thermo-reactive deposition method for 1–4 h. The presence of the niobium boride layers such as NbB, NbB{sub 2} and Nb{sub 3}B{sub 4} and also iron boride phases such as FeB, Fe{sub 2}B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurementsmore » were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 µm to 2.43 µm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV{sub 0.005}.« less

Kinetic Investigation and Wear Properties of Fe2B Layers on AISI 12L14 Steel

NASA Astrophysics Data System (ADS)

Keddam, M.; Ortiz-Dominguez, M.; Elias-Espinosa, M.; Arenas-Flores, A.; Zuno-Silva, J.; Zamarripa-Zepeda, D.; Gomez-Vargas, O. A.

2018-03-01

In the current study, the powder-pack boriding was applied to the AISI 12L14 steel in the temperature range 1123 K to 1273 K for an exposure time between 2 and 8 hours. The produced boride layer was composed of Fe2B with a sawtooth morphology. A diffusion model based on the integral method was applied to investigate the growth kinetics of Fe2B layers. As a main result, the boron diffusion coefficients in Fe2B were estimated by considering the principle of mass balance at the (Fe2B/substrate) interface with an inclusion of boride incubation times. The value of activation energy for boron diffusion in AISI 12L14 steel was estimated as 165 kJ mol-1 and compared with other values of activation energy found in the literature. An experimental validation of the present model was made by using four different boriding conditions. Furthermore, the Rockwell-C adhesion test was employed to assess the cohesion of boride layers to the base metal. The scratch and pin-on-disc tests were also carried out to analyze the effect of boriding on wear behavior of AISI 12L14 steel.

Gradient boride layers formed by diffusion carburizing and laser boriding

NASA Astrophysics Data System (ADS)

Kulka, M.; Makuch, N.; Dziarski, P.; Mikołajczak, D.; Przestacki, D.

2015-04-01

Laser boriding, instead of diffusion boriding, was proposed to formation of gradient borocarburized layers. The microstructure and properties of these layers were compared to those-obtained after typical diffusion borocarburizing. First method of treatment consists in diffusion carburizing and laser boriding only. In microstructure three zones are present: laser borided zone, hardened carburized zone and carburized layer without heat treatment. However, the violent decrease in the microhardness was observed below the laser borided zone. Additionally, these layers were characterized by a changeable value of mass wear intensity factor thus by a changeable abrasive wear resistance. Although at the beginning of friction the very low values of mass wear intensity factor Imw were obtained, these values increased during the next stages of friction. It can be caused by the fluctuations in the microhardness of the hardened carburized zone (HAZ). The use of through hardening after carburizing and laser boriding eliminated these fluctuations. Two zones characterized the microstructure of this layer: laser borided zone and hardened carburized zone. Mass wear intensity factor obtained a constant value for this layer and was comparable to that-obtained in case of diffusion borocarburizing and through hardening. Therefore, the diffusion boriding could be replaced by the laser boriding, when the high abrasive wear resistance is required. However, the possibilities of application of laser boriding instead of diffusion process were limited. In case of elements, which needed high fatigue strength, the substitution of diffusion boriding by laser boriding was not advisable. The surface cracks formed during laser re-melting were the reason for relatively quickly first fatigue crack. The preheating of the laser treated surface before laser beam action would prevent the surface cracks and cause the improved fatigue strength. Although the cohesion of laser borided carburized layer was sufficient, the diffusion borocarburized layer showed a better cohesion.

Influence of laser alloying with boron and niobium on microstructure and properties of Nimonic 80A-alloy

NASA Astrophysics Data System (ADS)

Makuch, N.; Piasecki, A.; Dziarski, P.; Kulka, M.

2015-12-01

Ni-base superalloys were widely used in aeronautics, chemical and petrochemical industries due to their high corrosion resistance, high creep and rupture strength at high temperature. However, these alloys were not considered for applications in which conditions of appreciable mechanical wear were predominant. The diffusion boriding provided suitable protection against wear. Unfortunately, this process required long duration and high temperature. In this study, instead of the diffusion process, the laser alloying with boron and niobium was used in order to produce the hard and wear resistant layer on Nimonic 80A-alloy. The laser-alloying was carried out as a two-step process. First, the external cylindrical surface of specimens was pre-placed with a paste containing boron and niobium. Then, the pre-placed coating and the thin surface layer of the substrate were re-melted by a laser beam. The high laser beam power (P=1.56 kW) and high averaging irradiance (E=49.66 kW/cm2) provided the thick laser re-melted zone. The laser-borided layers were significantly thicker (470 μm) in comparison with the layers obtained as a consequence of the diffusion boriding. Simultaneously, the high overlapping of multiple laser tracks (86%) caused that the laser-alloyed layer was uniform in respect of the thickness. The produced layer consisted of nickel borides (Ni3B, Ni2B, Ni4B3, NiB), chromium borides (CrB, Cr2B), niobium borides (NbB2, NbB) and Ni-phase. The presence of hard borides caused the increase in microhardness up to 1000 HV in the re-melted zone. However, the measured values were lower than those-characteristic of niobium borides, chromium borides and nickel borides. The presence of the soft Ni-phase in re-melted zone was the reason for such a situation. After laser alloying, the significant increase in abrasive wear resistance was also observed. The mass wear intensity factor, as well as the relative mass loss of the laser-alloyed specimens, was over 10 times smaller in comparison with untreated Nimonic 80A-alloy.

Characterization of AISI 4140 borided steels

NASA Astrophysics Data System (ADS)

Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martínez-Trinidad, J.

2010-02-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form KC( π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

Growth kinetics of borided layers: Artificial neural network and least square approaches

NASA Astrophysics Data System (ADS)

Campos, I.; Islas, M.; Ramírez, G.; VillaVelázquez, C.; Mota, C.

2007-05-01

The present study evaluates the growth kinetics of the boride layer Fe 2B in AISI 1045 steel, by means of neural networks and the least square techniques. The Fe 2B phase was formed at the material surface using the paste boriding process. The surface boron potential was modified considering different boron paste thicknesses, with exposure times of 2, 4 and 6 h, and treatment temperatures of 1193, 1223 and 1273 K. The neural network and the least square models were set by the layer thickness of Fe 2B phase, and assuming that the growth of the boride layer follows a parabolic law. The reliability of the techniques used is compared with a set of experiments at a temperature of 1223 K with 5 h of treatment time and boron potentials of 2, 3, 4 and 5 mm. The results of the Fe 2B layer thicknesses show a mean error of 5.31% for the neural network and 3.42% for the least square method.

Laser-induced reaction alumina coating on ceramic composite

NASA Astrophysics Data System (ADS)

Xiao, Chenghe

Silicon carbide ceramics are susceptible to corrosion by certain industrial furnace environments. It is also true for a new class of silicon carbide-particulate reinforced alumina-matrix composite (SiCsb(P)Alsb2Osb3) since it contains more than 55% of SiC particulate within the composite. This behavior would limit the use of SiCsb(P)Alsb2Osb3 composites in ceramic heat exchangers. Because oxide ceramics corrode substantially less in the same environments, a laser-induced reaction alumina coating technique has been developed for improving corrosion resistance of the SiCsb(P)Alsb2Osb3 composite. Specimens with and without the laser-induced reaction alumina coating were subjected to corrosion testing at 1200sp°C in an air atmosphere containing Nasb2COsb3 for 50 ˜ 200 hours. Corroded specimens were characterized via x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The uncoated SiCsbP/Alsb2Osb3 composite samples experienced an initial increase in weight during the exposure to Nasb2COsb3 at 1200sp°C due to the oxidation of residual aluminum metal in the composite. There was no significant weight change difference experienced during exposure times between 50 and 200 hours. The oxidation layer formed on the as-received composite surface consisted of Si and Alsb2Osb3 (after washing with a HF solution). The oxidation layer grew outward and inward from the original surface of the composite. The growth rate in the outward direction was faster than in the inward direction. The formation of the Si/Alsb2Osb3 oxidation layer on the as-received composite was nonuniform, and localized corrosion was observed. The coated samples experienced very little mass increase. The laser-induced reaction alumina coating effectively provided protection for the SiCsbP/Alsb2Osb3 composite by keeping the corrodents from contacting the composite and by the formation of some refractory compounds such as Nasb2OAlsb2Osb3SiOsb2 and Nasb2Alsb{22}Osb{34}. After exposure to 1200sp°C for 200 hours, the bonding between the laser-induced reaction alumina coating and the composite appeared to be unattacked. For both the coated and uncoated samples, porosity within the composite increased after exposure due to the reaction: 3SiOsb2(s) + 4Al(l) -> 2Alsb2Osb3(s) + Si(s).

Morphology and structure of borides in as-cast titanium and gamma-titanium aluminide-based alloys

NASA Astrophysics Data System (ADS)

Kitkamthorn, Usanee

In this study, the morphology and structure of the borides in boron-modified Ti- and gamma-TiAl-based alloys have been investigated using SEM, TEM, and HRTEM. A variety of different boride morphologies was observed including plates, needles, and ribbons. For the plate and needle borides, the major boride phase is B27 TiB. The needle borides have their major axis parallel to [010], and are bounded by (100) and {101} type-facets. The plate borides develop the same types of facets as the needles and have habit planes parallel to the (100). There are high densities of intrinsic stacking faults on (100) in these borides and these correspond to thin embedded layers of the Bf structure. The plate borides do not exhibit well-defined ORs with respect to the surrounding phases, suggesting that they develop in the liquid melt and were then trapped by the growing solid. Needle borides are observed mostly at boundaries between lamellar colonies: these needles tend to occur in groups lying nearly parallel to one another and, in some cases, to adopt well-defined ORs with respect to the surrounding phases. Cored borides with metallic phases such as beta, alpha, o and alpha 2+gamma in the center are frequently observed, especially in the Ti-based alloy. These core phases usually adopt well-defined ORs with respect to the surrounding boride which enable low-energy coherent interfaces to form between the phases. The ribbon borides are comprised of thin boride flakes interspersed with thin metallic layers. The major boride phase in these flakes is Bf TiB. The habit plane of the flakes is (010) and there are high densities of faults on this plane corresponding to intergrowths of the Ti3B 4 and TiB2 phases, together with thin layers or occluded pockets of metallic B2 phase. Occasional faults are observed on {110} corresponding to embedded slabs of B27 TiB. There is a well-defined OR between the boride flakes and the B2 phase within the ribbons, but not with the surrounding matrix. The characteristics of these various borides are consistent with them forming as eutectic reaction products, with the exception of the finest needles and plates observed in Ti-based alloy.

An Evaluation of a Borided Layer Formed on Ti-6Al-4V Alloy by Means of SMAT and Low-Temperature Boriding

PubMed Central

Yao, Quantong; Sun, Jian; Fu, Yuzhu; Tong, Weiping; Zhang, Hui

2016-01-01

In this paper, a nanocrystalline surface layer without impurities was fabricated on Ti-6Al-4V alloy by means of surface mechanical attrition treatment (SMAT). The grain size in the nanocrystalline layer is about 10 nm and grain morphology displays a random crystallographic orientation distribution. Subsequently, the low-temperature boriding behaviors (at 600 °C) of the SMAT sample, including the phase composition, microstructure, micro-hardness, and brittleness, were investigated in comparison with those of coarse-grained sample borided at 1100 °C. The results showed that the boriding kinetics could be significantly enhanced by SMAT, resulting in the formation of a nano-structured boride layers on Ti-6Al-4V alloy at lower temperature. Compared to the coarse-grained boriding sample, the SMAT boriding sample exhibits a similar hardness value, but improved surface toughness. The satisfactory surface toughness may be attributed to the boriding treatment that was carried out at lower temperature. PMID:28774115

Adhesive and Cohesive Strength in FeB/Fe2B Systems

NASA Astrophysics Data System (ADS)

Meneses-Amador, A.; Blancas-Pérez, D.; Corpus-Mejía, R.; Rodríguez-Castro, G. A.; Martínez-Trinidad, J.; Jiménez-Tinoco, L. F.

2018-05-01

In this work, FeB/Fe2B systems were evaluated by the scratch test. The powder-pack boriding process was performed on the surface of AISI M2 steel. The mechanical parameters, such as yield stress and Young's modulus of the boride layer, were obtained by the instrumented indentation technique. Residual stresses produced on the boride layer were estimated by using the x-ray diffraction (XRD) technique. The scratch test was performed in order to evaluate the cohesive/adhesive strength of the FeB/Fe2B coating. In addition, a numerical evaluation of the scratch test on boride layers was performed by the finite element method. Maximum principal stresses were related to the failure mechanisms observed by the experimental scratch test. Shear stresses at the interfaces of the FeB/Fe2B/substrate system were also evaluated. Finally, the results obtained provide essential information about the effect of the layer thickness, the residual stresses, and the resilience modulus on the cohesive/adhesive strength in FeB/Fe2B systems.

Synthesis and transformations of alkylphosphate and alkoxysiloxide metal complexes to multicomponent oxide materials

NASA Astrophysics Data System (ADS)

Lugmair, Claus Guenter

This thesis describes the synthesis of mixed element oxide materials utilizing oxygen rich ``single-source precursor'' molecules. The key attributes of these precursor complexes are that they possess the stoichiometry of the targeted oxide material and that they can be converted to carbon free materials by mild thermal treatment. Complexes of Al, Cu, Fe, Hf, Nb, Ta, Ti, and Zr were prepared that contain tris(tert-butoxy)siloxy ligands as precursors to silica based materials. The pyrolytic decomposition of these complexes occur under mild conditions, with onset temperatures to decomposition between 95 and 200sp°C. The resulting metal-silica or metal oxide-silica materials contain very little carbon. The solid state transformation of Zrlbrack OSi(OsptBu)sb3rbracksb4 to ZrOsb2{*}4SiOsb2 produced an open fibrous material with pores which are ca. 20 nm in diameter. The solution phase thermolysis of the various metal siloxide complexes in anhydrous organic solvents led to xerogels consisting of small spherical primary particles (≤ca. 5 nm). These xerogels typically possess very high surface areas. The ZrOsb2{*}4SiOsb2 materials are amorphous as initially formed, and subsequent crystallizations of tetragonal ZrOsb2, monoclinic ZrOsb2, and cristobalite occur at relatively high temperatures. The enhanced stabilization of the amorphous and tetragonal phases of zirconia, relative to those derived from many sol-gel systems, implies that these single-source precursors initially produce highly homogeneous materials and that subsequent crystallizations are to a large degree diffusion-controlled, Careful addition of 1 or 2 equiv of water to THF solutions of Mlbrack OSi(OsptBu)sb3rbracksb4 (M = Zr, Hf) produced the isolable aqua complexes Mlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O) and Mlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O)sb2. It is likely that the hydrolysis of Zrlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O)sb2 also occurs by an associative mechanism via the tris(aqua) intermediate Zrlbrack OSi(Osp{t}Bu)sb3rbracksb4(Hsb2O)sb3. The reaction of ZnEtsb2 with HO(O)P(OsptBu)sb2 in the presence of slight amounts of water produced good yields of the oxo-centered tetranuclear cluster Znsb4(musb4-O)lbrack Osb2P(OsptBu)sb2rbracksb6. When this complex was heated in ethanol at 85sp°C for 30 h, or dissolved in acid containing solutions, it converted to a polymer, \\{Znlbrack Osb2P(OsptBu)sb2rbracksb2\\}sbn, which contains zinc atoms that are linked alternately by one and then three bridging phosphate groups. Diffusion of a toluene solution of Znsb4(musb4-O)lbrack Osb2P(OsptBu)sb2rbracksb6 into a dichloromethane solution of 1,6-hexanediamine produced a layered coordination network with the formula \\{Znlbrack Osb2P(OsptBu)sb2rbracksb2lbrack Hsb2N(CHsb2)sb6NHsb2rbrack\\}sbn. The reaction between Znsb4(musb4-O)lbrack Osb2P(OsptBu)sb2rbracksb6 and either 4 or 8 equiv of n-alkylamines in toluene or isopropanol at elevated temperatures (180-220sp°C) led to the formation of lamellar zincophosphate materials. These mesophases consist of zinc phosphate layers that are separated by layers of n-alkylamines which adopt either an interdigitated or a double layer arrangement. Reactions of 1 equiv of HO(O)P(OsptBu)sb2 with Ti(OR)sb4 (R = Et, spiPr) gave the new molecular titanium phosphates lbrack Ti(OR)sb3Osb2P(OsptBu)sb2rbracksbn (R = Et, spiPr). Addition of 2 equiv of KOEt to an ethanol solution of lbrack Ti(OEt)sb3Osb2P(OsptBu)sb2rbracksbn led to the formation of lbrack Tisb2K(OEt)sb8Osb2P(OsptBu)sb2rbracksb2 and 1 equiv of KOsb2P(OsptBu)sb2. Addition of 2 equiv of KOspiPr to an isopropanol solution of lbrack Ti(OspiPr)sb3Osb2P(OsptBu)sb2rbracksb2 led to the formation of KOsb2P(OsptBu)sb2 and Ti(OspiPr)sb4 in high yield. (Abstract shortened by UMI.)

Thermodynamic modelling of phase equilibrium in system Ti-B-Si-C, synthesis and phases composition of borides and carbides layers on titanic alloyVT-1 at electron beam treatment in vacuum

NASA Astrophysics Data System (ADS)

Smirnyagina, N. N.; Khaltanova, V. M.; Lapina, A. E.; Dasheev, D. E.

2017-01-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VT-1 are generated at diffused saturation in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

The effect of boriding on wear resistance of cold work tool steel

NASA Astrophysics Data System (ADS)

Anzawa, Y.; Koyama, S.; Shohji, I.

2017-05-01

Recently, boriding has attracted extensive attention as surface stiffening processing of plain steel. In this research, the influence of processing time on the formation layer of cold work tool steel (KD11MAX) by Al added fused salt bath was examined. In addition, in order to improve the abrasion resistance of KD11MAX, the effect of the treatment of boronization on the formation layer has been investigated. Boriding were performed in molten borax which contained about 10 mass% Al at processing time of 1.8 ~ 7.2 ks (processing temperature of 1303 K). As a result of the examination, the hardness of the boriding layer becomes about 1900 HV when the processing time of 3.6 ks. Also the abrasion resistance has improved remarkably. Furthermore, it was revealed that the formation layer was boronized iron from the Vickers hardness and analysis of the X-ray diffraction measurement.

Effect of mechanical activation on jell boronizing treatment of the AISI 4140

NASA Astrophysics Data System (ADS)

Yılmaz, S. O.; Karataş, S.

2013-06-01

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO2-Na2O) powders for 873-1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as function of treatment time and temperature in the range of 873-1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 μm was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000-2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe2B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

Method of making an icosahedral boride structure

DOEpatents

Hersee, Stephen D.; Wang, Ronghua; Zubia, David; Aselage, Terrance L.; Emin, David

2005-01-11

A method for fabricating thin films of an icosahedral boride on a silicon carbide (SiC) substrate is provided. Preferably the icosahedral boride layer is comprised of either boron phosphide (B.sub.12 P.sub.2) or boron arsenide (B.sub.12 As.sub.2). The provided method achieves improved film crystallinity and lowered impurity concentrations. In one aspect, an epitaxially grown layer of B.sub.12 P.sub.2 with a base layer or substrate of SiC is provided. In another aspect, an epitaxially grown layer of B.sub.12 As.sub.2 with a base layer or substrate of SiC is provided. In yet another aspect, thin films of B.sub.12 P.sub.2 or B.sub.12 As.sub.2 are formed on SiC using CVD or other vapor deposition means. If CVD techniques are employed, preferably the deposition temperature is above 1050.degree. C., more preferably in the range of 1100.degree. C. to 1400.degree. C., and still more preferably approximately 1150.degree. C.

In Situ Solid-Gas Reactivity of Nanoscaled Metal Borides from Molten Salt Synthesis.

PubMed

Gouget, Guillaume; Debecker, Damien P; Kim, Ara; Olivieri, Giorgia; Gallet, Jean-Jacques; Bournel, Fabrice; Thomas, Cyril; Ersen, Ovidiu; Moldovan, Simona; Sanchez, Clément; Carenco, Sophie; Portehault, David

2017-08-07

Metal borides have mostly been studied as bulk materials. The nanoscale provides new opportunities to investigate the properties of these materials, e.g., nanoscale hardening and surface reactivity. Metal borides are often considered stable solids because of their covalent character, but little is known on their behavior under a reactive atmosphere, especially reductive gases. We use molten salt synthesis at 750 °C to provide cobalt monoboride (CoB) nanocrystals embedded in an amorphous layer of cobalt(II) and partially oxidized boron as a model platform to study morphological, chemical, and structural evolutions of the boride and the superficial layer exposed to argon, dihydrogen (H 2 ), and a mixture of H 2 and carbon dioxide (CO 2 ) through a multiscale in situ approach: environmental transmission electron microscopy, synchrotron-based near-ambient-pressure X-ray photoelectron spectroscopy, and near-edge X-ray absorption spectroscopy. Although the material is stable under argon, H 2 triggers at 400 °C decomposition of CoB, leading to cobalt(0) nanoparticles. We then show that H 2 activates CoB for the catalysis of CO 2 methanation. A similar decomposition process is also observed on NiB nanocrystals under oxidizing conditions at 300 °C. Our work highlights the instability under reactive atmospheres of nanocrystalline cobalt and nickel borides obtained from molten salt synthesis. Therefore, we question the general stability of metal borides with distinct compositions under such conditions. These results shed light on the actual species in metal boride catalysis and provide the framework for future applications of metal borides in their stability domains.

Microstructure and property correlations in high-temperature superconductors

NASA Astrophysics Data System (ADS)

Kalyanaraman, Ramakrishnan

1998-11-01

The work in this dissertation is intended at developing high quality device gradefilms of the high temperature (high-Tsbc) superconductor, Yttrium Barium Copper Oxide (YBCO), on MgO(001) substrates. Three approaches have been used to achieve the above goal, (i) The use of a SrTiOsb3 buffer layer, (ii) The use of Ag to enhance the growth of YBCO films and (iii) Investigation of the atomic structure-property correlations of low-angle grain boundaries in these films. Thin film heterostructures of YBCO/MgO and YBCO/SrTiOsb3/MgO were fabricated by pulsed laser deposition (PLD), using a 248 nm KrF excimer laser. Analysis of the structure and measurement of superconducting properties of the films were carried out to optimize the suitable conditions under each approach. The key findings were, (i) Single crystal-like SrTiOsb3 buffer layers can be grown and they give the highest JsbcYBCO films, (ii) An in-depth study of the role of Ag showed that it enhanced film growth of YBCO thereby improving its quality, and (iii) Low-angle boundaries in YBCO/MgO occur with two probable habit planes and the Jsbcs across them differ slightly. A systematic investigation of the crystalline quality of the SrTiOsb3 films deposited by PLD was performed as a function of oxygen partial pressure (pOsb2) and substrate temperature (Tsbc). The highest quality films were grown in the pOsb2 range of 0.1-1 mTorr at 750sp°C. The films had as-deposited x-ray diffraction rocking curve (omega) values of {˜}0.70sp° and Rutherford backscattering channeling yields (chisbmin) of 5% as compared to omega˜1.40sp° and chisbmin˜14% for the film deposited in 100 mTorr of pOsb2. The x-ray phi-scans showed epitaxial cube-on-cube alignment of the SrTiOsb3 films on MgO(001) substrates. Thermal annealing of the SrTiOsb3 films further improved the quality, and the 1 mTorr films gave omega{˜}0.13sp° and chisbmin˜2.0%. Transmission electron microscopy investigations (TEM) of these films showed that the defects in films grown in the pOsb2 range of 0.5-1 mTorr consisted mainly of dislocations and sub-grain boundaries, while those grown in the higher pOsb2 contained numerous low-angle grain boundaries. YBCO films grown on the best SrTiOsb3 buffer layers showed reproducible Jsbcs of {˜}5.5× 10sp6 amps/cmsp2 at 77K and Tsbcs of 88-91K. The YBCO films was observed to grow epitaxially on SrTiOsb3 with (110) sbPYBCO//(110) sbSriTiO3 and (001) sbYBCO//(001) sbSrTiO3{*}chisbmin for the best YBCO film was ˜2.8%. The crystalline quality of the SrTiOsb3 and YBCO films developed are amongst the highest reported so far. Composite targets of Ag+YBCO were used to grow YBCO films using PLD. Using XRD and Tsbc measurements clear evidence for enhanced oxygenation of the YBCO films was shown. Detailed TEM investigation of grain boundaries in YBCO/MgO(001) showed that the low-angle grain boundaries in YBCO are equally likely to have (100) or (110) habit planes. (Abstract shortened by UMI.)

A Simple Kinetic Model for the Growth of Fe2B Layers on AISI 1026 Steel During the Powder-pack Boriding

NASA Astrophysics Data System (ADS)

Flores-Rentería, M. A.; Ortiz-Domínguez, M.; Keddam, M.; Damián-Mejía, O.; Elias-Espinosa, M.; Flores-González, M. A.; Medina-Moreno, S. A.; Cruz-Avilés, A.; Villanueva-Ibañez, M.

2015-02-01

This work focused on the determination of boron diffusion coefficient through the Fe2B layers on AISI 1026 steel using a mathematical model. The suggested model solves the mass balance equation at the (Fe2B/substrate) interface. This thermochemical treatment was carried out in the temperature range of 1123-1273 K for a treatment time ranging from 2 to 8 h. The generated boride layers were characterized by different experimental techniques such as light optical microscopy, scanning electron microscopy, XRD analysis and the Daimler-Benz Rockwell-C indentation technique. As a result, the boron activation energy for AISI 1026 steel was estimated as 178.4 kJ/mol. Furthermore, this kinetic model was validated by comparing the experimental Fe2B layer thickness with the predicted one at a temperature of 1253 K for 5 h of treatment. A contour diagram relating the layer thickness to the boriding parameters was proposed to be used in practical applications.

Metal-boride phase formation on tungsten carbide (WC-Co) during microwave plasma chemical vapor deposition

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.; Catledge, Shane A.

2016-02-01

Strengthening of cemented tungsten carbide by boriding is used to improve the wear resistance and lifetime of carbide tools; however, many conventional boriding techniques render the bulk carbide too brittle for extreme conditions, such as hard rock drilling. This research explored the variation in metal-boride phase formation during the microwave plasma enhanced chemical vapor deposition process at surface temperatures from 700 to 1100 °C. We showed several well-adhered metal-boride surface layers consisting of WCoB, CoB and/or W2CoB2 with average hardness from 23 to 27 GPa and average elastic modulus of 600-730 GPa. The metal-boride interlayer was shown to be an effective diffusion barrier against elemental cobalt; migration of elemental cobalt to the surface of the interlayer was significantly reduced. A combination of glancing angle X-ray diffraction, electron dispersive spectroscopy, nanoindentation and scratch testing was used to evaluate the surface composition and material properties. An evaluation of the material properties shows that plasma enhanced chemical vapor deposited borides formed at substrate temperatures of 800 °C, 850 °C, 900 °C and 1000 °C strengthen the material by increasing the hardness and elastic modulus of cemented tungsten carbide. Additionally, these boride surface layers may offer potential for adhesion of ultra-hard carbon coatings.

Hexagonal OsB 2 reduction upon heating in H 2 containing environment

DOE PAGES

Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; ...

2014-10-23

The stability of hexagonal ReB 2 type OsB 2 powder upon heating under reforming gas was investigated. Pure Os metal particles were detected by powder X-ray diffraction starting at 375⁰ C and complete transformation of OsB 2 to metallic Os was observed at 725⁰ C. The mechanisms of precipitation of metallic Os is proposed and changes in the lattice parameters of OsB 2 upon heating are analysed in terms of the presence of oxygen or water vapour in the heating chamber. Previous studies suggested that Os atoms possess (0) valence, while B atoms possess both (+3) and ( 3) valencesmore » in the alternating boron/osmium sheet structure of hexagonal (P63/mmc, No. 194) OsB 2; if controllable method for Os removal from the lattice could be found, the opportunity would arise to form two-dimensional (2D) layers consisting of pure B atoms.« less

Kinetics and Tribological Characterization of Pack-Borided AISI 1025 Steel

NASA Astrophysics Data System (ADS)

Gómez-Vargas, O. A.; Keddam, M.; Ortiz-Domínguez, M.

2017-03-01

In this present study, the AISI 1025 steel was pack-borided in the temperature range of 1,123-1,273 K for different treatment times ranging from 2 to 8 h. A diffusion model was suggested to estimate the boron diffusion coefficients in the Fe2B layers. As a result, the boron activation energy for the AISI 1025 steel was estimated as 174.36 kJ/mol. This value of energy was compared with the literature data. To extend the validity of the present model, other additional boriding conditions were considered. The boride layers formed on the AISI 1025 steel were characterized by the following experimental techniques: scanning electron microscopy, X-ray diffraction analysis and the Daimler-Benz Rockwell-C indentation technique. Finally, the scratch and pin-on-disc tests for wear resistance were achieved using an LG Motion Ltd and a CSM tribometer, respectively, under dry sliding conditions.

B Layers and Adhesion on Armco Iron Substrate

NASA Astrophysics Data System (ADS)

Elias-Espinosa, M.; Ortiz-Domínguez, M.; Keddam, M.; Flores-Rentería, M. A.; Damián-Mejía, O.; Zuno-Silva, J.; Hernández-Ávila, J.; Cardoso-Legorreta, E.; Arenas-Flores, A.

2014-08-01

In this work, a kinetic model was suggested to evaluate the boron diffusion coefficient in the Fe2B layers grown on the Armco iron substrate by the powder-pack boriding. This thermochemical treatment was carried out in the temperature range of 1123-1273 K for treatment times ranging from 2 to 8 h. The boron diffusion coefficient in the Fe2B layers was estimated by solving the mass balance equation at the (Fe2B/substrate) interface with an inclusion of boride incubation time. To validate the present model, the simulated value of Fe2B layer thickness was compared with the experimental value obtained at 1253 K for a treatment time of 5 h. The morphology of Fe2B layers was observed by SEM and optical microscopy. Metallographic studies showed that the boride layer has a saw-tooth morphology in all the samples. The layer thickness measurements were done with the help of MSQ PLUS software. The Fe2B phase was identified by x-ray diffraction method. Finally, the adherence of Fe2B layers on the Armco iron substrate was qualitatively evaluated by using the Daimler-Benz Rockwell-C indentation technique. In addition, the estimated value of boron activation energy was compared to the literature data.

Investigation of diffusional interaction between P91 grade ferritic steel and Fe-15 wt.%B alloy and study of kinetics of boride formation at high temperature

NASA Astrophysics Data System (ADS)

Rai, Arun Kumar; Vijayashanthi, N.; Tripathy, H.; Hajra, R. N.; Raju, S.; Murugesan, S.; Saroja, S.

2017-11-01

In the present study, the feasibility of employing the indigenously developed ferroboron alloy (Fe-15 wt.%B) as an alternate neutron shield material in combination with 9Cr-based ferritic steel (P91) clad in future Indian fast breeder reactors (FBR), has been investigated from a metallurgical perspective. Towards this goal, a series of diffusion couple experiments have been conducted at three different temperatures namely, 600, 700 and 800 °C for time durations up to 5000 h. The thickness of interaction layer has been monitored using standard metallographic procedures. The experiments revealed that ferroboron/P91 combination exhibited a tendency to form complex intermetallic borides at the interface. The structural and microstructural characterization of the interface confirmed that the reaction layer consists predominantly of borides of Fe and Cr of type FeB, Fe2B, (Fe,Cr)2B and (Fe,Cr)B. The measured variation of interaction layer thickness as a function of time and temperature have been modelled in terms of diffusion mediated interaction. The growth kinetics of borided layer has followed the parabolic law at each temperature, and the apparent activation energy for boride layer formation is found to be of the order of 115 kJ mol-1. This indicates that the kinetics of boriding could be governed by diffusion of B into the P91 matrix. Based on the findings of present study, an extrapolative estimate of the clad attack thickness at 550 °C for 60 years of operating time has been made and it turns out to be 210 ± 15 μm, which is less than the clad thickness of FBR shielding subassembly (4 mm) [1]. Thus, this study confirms that at testing temperatures from 550 to 600 °C, the ferroboron/P91 steel combination can be safely employed for shielding subassembly applications in fast reactors.

Method of boronizing transition metal surfaces

DOEpatents

Koyama, Koichiro; Shimotake, Hiroshi

1983-01-01

A method is presented for preparing a boride layer on a transition metal substrate for use in corrosive environments or as a harden surface in machine applications. This method is particularly useful in treating current collectors for use within a high temperature and corrosive electrochemical cell environment. A melt of a alkali metal boride tetrafluoride salt including such as KF to lower its melting point is prepared including a dissolved boron containing material, for instance NiB, MnB.sub.2, or CrB.sub.2. A transition metal to be coated is immersed in the melt at a temperature of no more than 700.degree. C. and a surface boride layer of that transition metal is formed within a period of about 24 hours on the substrate surface.

Ultra-fast boriding of metal surfaces for improved properties

DOEpatents

Timur, Servet; Kartal, Guldem; Eryilmaz, Osman L.; Erdemir, Ali

2015-02-10

A method of ultra-fast boriding of a metal surface. The method includes the step of providing a metal component, providing a molten electrolyte having boron components therein, providing an electrochemical boriding system including an induction furnace, operating the induction furnace to establish a high temperature for the molten electrolyte, and boriding the metal surface to achieve a boride layer on the metal surface.

Method of boronizing transition metal surfaces

DOEpatents

Koyama, Koichiro; Shimotake, Hiroshi.

1983-08-16

A method is presented for preparing a boride layer on a transition metal substrate for use in corrosive environments or as a harden surface in machine applications. This method is particularly useful in treating current collectors for use within a high temperature and corrosive electrochemical cell environment. A melt of a alkali metal boride tetrafluoride salt including such as KF to lower its melting point is prepared including a dissolved boron containing material, for instance NiB, MnB[sub 2], or CrB[sub 2]. A transition metal to be coated is immersed in the melt at a temperature of no more than 700 C and a surface boride layer of that transition metal is formed within a period of about 24 hours on the substrate surface. 4 figs.

Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

NASA Astrophysics Data System (ADS)

Ballinger, Jared

Diamond thin films have promising applications in numerous fields due to the extreme properties of diamonds in conjunction with the surface enhancement of thin films. Biomedical applications are numerous including temporary implants and various dental and surgical instruments. The unique combination of properties offered by nanostructured diamond films that make it such an attractive surface coating include extreme hardness, low obtainable surface roughness, excellent thermal conductivity, and chemical inertness. Regrettably, numerous problems exist when attempting to coat stainless steel with diamond generating a readily delaminated film: outward diffusion of iron to the surface, inward diffusion of carbon limiting necessary surface carbon precursor, and the mismatch between the coefficients of thermal expansion yielding substantial residual stress. While some exotic methods have been attempted to overcome these hindrances, the most common approach is the use of an intermediate layer between the stainless steel substrate and the diamond thin film. In this research, both 316 stainless steel disks and 440C stainless steel ball bearings were tested with interlayers including discrete coatings and graded, diffusion-based surface enhancements. Titanium nitride and thermochemical diffusion boride interlayers were both examined for their effectiveness at allowing for the growth of continuous and adherent diamond films. Titanium nitride interlayers were deposited by cathodic arc vacuum deposition on 440C bearings. Lower temperature diamond processing resulted in improved surface coverage after cooling, but ultimately, both continuity and adhesion of the nanostructured diamond films were unacceptable. The ability to grow quality diamond films on TiN interlayers is in agreement with previous work on iron and low alloy steel substrates, and the similarly seen inadequate adhesion strength is partially a consequence of the lacking establishment of an interfacial carbide phase. Surface boriding was implemented using the novel method of microwave plasma CVD with a mixture of hydrogen and diborane gases. On 440C bearings, dual phase boride layers of Fe2B and FeB were formed which supported adhered nanostructured diamond films. Continuity of the films was not seamless with limited regions remaining uncoated potentially corresponding to delamination of the film as evidenced by the presence of tubular structures presumably composed of sp2 bonded carbon. Surface boriding of 316 stainless steel discs was conducted at various powers and pressures to achieve temperatures ranging from 550-800 °C. The substrate boriding temperature was found to substantially influence the resultant interlayer by altering the metal boride(s) present. The lowest temperatures produced an interlayer where CrB was the single detected phase, higher temperatures yielded the presence of only Fe2B, and a combination of the two phases resulted from an intermediate boriding temperature. Compared with the more common, commercialized boriding methods, this a profound result given the problems posed by the FeB phase in addition to other advantages offered by CVD processes and microwave generated plasmas in general. Indentation testing of the boride layers revealed excellent adhesion strength for all borided interlayers, and above all, no evidence of cracking was observed for a sole Fe2B phase. As with boriding of 440C bearings, subsequent diamond deposition was achieved on these interlayers with substantially improved adhesion strength relative to diamond coated TiN interlayers. Both XRD and Raman spectroscopy confirmed a nanostructured diamond film with interfacial chromium carbides responsible for enhanced adhesion strength. Interlayers consisting solely of Fe2B have displayed an ability to support fully continuous nanostructured diamond films, yet additional study is required for consistent reproduction. This is in good agreement with initial work on pack borided high alloy steels to promote diamond film surface modification. The future direction for continued research of nanostructured diamond coatings on microwave plasma CVD borided stainless steel should further investigate the adhesion of both borided interlayers and subsequent NSD films in addition to short, interrupted diamond depositions to study the interlayer/diamond film interface.

Micro-Abrasion Wear Resistance of Borided 316L Stainless Steel and AISI 1018 Steel

NASA Astrophysics Data System (ADS)

Reséndiz-Calderon, C. D.; Rodríguez-Castro, G. A.; Meneses-Amador, A.; Campos-Silva, I. E.; Andraca-Adame, J.; Palomar-Pardavé, M. E.; Gallardo-Hernández, E. A.

2017-11-01

The 316L stainless steel has high corrosion resistance but low tribological performance. In different industrial sectors (biomedical, chemical, petrochemical, and nuclear engineering), improvement upon wear resistance of 316L stainless steel components using accessible and inexpensive methods is critical. The AISI 1018 steel is widely used in industry, but its tribological performance is not the best among steels. Therefore, in this study the behavior of the borided 316L stainless steel and 1018 steel is evaluated under micro-abrasion wear. The boriding was carried out at 1223 K over 6 h of exposure time, resulting in a biphase layer composed of FeB/Fe2B phases. In order to evaluate Fe2B phase with no influence from FeB phase, AISI 1018 steel samples were borided at 1273 K for over 20 min and then diffusion annealed at 1273 K over 2 h to obtain a Fe2B mono-phase layer. Micro-abrasion wear resistance was evaluated by a commercial micro-abrasion testing rig using a mix of F-1200 SiC particles with deionized water as abrasive slurry. The obtained wear rates for FeB and Fe2B phases and for the 316L stainless steel were compared. Wear resistance of 316L stainless steel increases after boriding. The wear mechanisms for both phases and for the stainless steel were identified. Also, transient conditions for rolling and grooving abrasion were determined for the FeB and Fe2B phases.

Phase equilibrium in system Ti-Si-C-B and synthesis of MAX phase layers in vacuum under the influence of electron beam

NASA Astrophysics Data System (ADS)

Smirnyagina, N. N.; Khaltanova, V. M.; Dasheev, D. E.; Lapina, A. E.

2017-05-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VТ-1 are generated at diffused saturation by electron beam treatment in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

Comparison study of thickness swell performance of commercial oriented strandboard flooring products

Treesearch

Hongmei Gu; Siqun Wang; Trairat Neimsuwan; Sunguo Wang

2005-01-01

The multiple layer structure of oriented strandboard (OSB) has a significant influence on its performance, including thickness swell (TS). TS is recognized as an important performance property for OSB products. Optimization of TS through layer property ma- nipulation to achieve the lowest total TS while maintaining acceptable mechanical properties is attainable if the...

B11 NMR in the layered diborides OsB2 and RuB2

NASA Astrophysics Data System (ADS)

Suh, B. J.; Zong, X.; Singh, Y.; Niazi, A.; Johnston, D. C.

2007-10-01

B11 nuclear magnetic resonance (NMR) measurements have been performed on B11 enriched OsB2 and RuB2 polycrystalline powder samples in an external field of 4.7T and in the temperature range, 4.2K

A study on the formation of solid state nanoscale materials using polyhedral borane compounds

NASA Astrophysics Data System (ADS)

Romero, Jennifer V.

The formation of boron containing materials using a variety of methods was explored. The pyrolysis of a metal boride precursor solution can be accomplished using a one-source method by combining TiCl4, B10H 14 and CH3CN in one reaction vessel and pyrolyzing it at temperatures above 900 °C. Amorphous dark blue colored films were obtained after the pyrolysis reactions. Well-defined spherical shaped grains or particles were observed by SEM. The amorphous films generated contained titanium, however, the determination of the boron content of the films was inconclusive. This one pot method making metal boride thin films has the advantage of being able to dictate the stoichiometry of the reactants. Another part of this work represents the first report of both the use of metal boride materials and the use of a titanium-based compound for the formation of nanotubes. This method provides a facile method for generating well-formed boron-containing carbon nanotubes in a "one-pot" process through an efficient aerosol process. The formation of metal boride corrosion resistant layers was also explored. It was shown that metallic substrates can be effectively boronized using paste mixtures containing boron carbide and borax. The formation of a Fe4B 2 iron boride phase was achieved, however, this iron boride phase does not give enough corrosion protection. The formation of a corrosion resistant metal boride coating with strong adhesion was accomplished by boronization of a thermal sprayed nickel layer on the surface of steel. Surfactants were explored as possible nanoreactors in which metal boride nanoparticles could be formed to use as nanotube growth catalyst via room temperature reaction. Different surfactants were used, but none of them successfully generated very well dispersed metal boride nanoparticles. Nanoparticles with varying shapes and sizes were generated which were highly amorphous. The carboxylic acid derivative of closo-C2B 10 cages was explored as a ligand in the hydrothermal preparation of coordination polymers with zinc salts. It was found that the stability of the cage is apparently insufficient under these conditions and cage degradation was observed. Consequently, a preliminary investigation of the preparation of dipyridyl derivatives of both the closo-C2B 10 and the closo-B12 cages was performed.

OsLOL1, a C2C2-type zinc finger protein, interacts with OsbZIP58 to promote seed germination through the modulation of gibberellin biosynthesis in Oryza sativa.

PubMed

Wu, Jiahe; Zhu, Chuanfeng; Pang, Jinhuan; Zhang, Xiangrong; Yang, Chunlin; Xia, Guixian; Tian, Yingchuan; He, Chaozu

2014-12-01

Seed germination is a key developmental process in the plant life cycle that is influenced by various environmental cues and phytohormones through gene expression and a series of metabolism pathways. In the present study, we investigated a C2C2-type finger protein, OsLOL1, which promotes gibberellin (GA) biosynthesis and affects seed germination in Oryza sativa (rice). We used OsLOL1 antisense and sense transgenic lines to explore OsLOL1 functions. Seed germination timing in antisense plants was restored to wild type when exogenous GA3 was applied. The reduced expression of the GA biosynthesis gene OsKO2 and the accumulation of ent-kaurene were observed during germination in antisense plants. Based on yeast two-hybrid and firefly luciferase complementation analyses, OsLOL1 interacted with the basic leucine zipper protein OsbZIP58. The results from electrophoretic mobility shift and dual-luciferase reporter assays showed that OsbZIP58 binds the G-box cis-element of the OsKO2 promoter and activates LUC reporter gene expression, and that interaction between OsLOL1 and OsbZIP58 activates OsKO2 gene expression. In addition, OsLOL1 decreased SOD1 gene expression and accelerated programmed cell death (PCD) in the aleurone layer of rice grains. These findings demonstrate that the interaction between OsLOL1 and OsbZIP58 influences GA biosynthesis through the activation of OsKO2 via OsbZIP58, thereby stimulating aleurone PCD and seed germination. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Effect of Discharge Time on Plasma Electrolytic Borocarbonitriding of Pure Iron

NASA Astrophysics Data System (ADS)

Jin, Xiaoyue; Wu, Jie; Wang, Bin; Yang, Xuan; Chen, Lin; Qu, Yao; Xue, Wenbin

The plasma electrolytic borocarbonitriding (PEB/C/N) process on pure iron was carried out in 25% borax solution with glycerine and carbamide additives under different discharge time at 360V. The morphology and structure of PEB/C/N hardened layers were analyzed by SEM and XRD. The hardness profiles of hardened layers were measured by microhardness test. Corrosion behavior of PEB/C/N layers was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Their wear performance was carried out using a pin-disc friction and wear tester under dry sliding test. The PEB/C/N samples mainly consisted of α-Fe, Fe2B, Fe3C, FeN, FeB, Fe2O3 and Fe4N phases, and the Fe2B phase was the dominant phase in the boride layer. It was found that the thickness of boride layer increased with the discharge time and reached 14μm after 60min treatment. The microhardness of the boride layer was up to 2100HV, which was much higher than that of the bare pure iron (about 150HV). After PEB/C/N treatment, the corrosion resistance of pure iron was slightly improved. The friction coefficient of PEB/C/N treated pure iron decreased to 0.129 from 0.556 of pure iron substrate. The wear rate of the PEB/C/N layer after 60min under dry sliding against ZrO2 ball was only 1/10 of that of the bare pure iron. The PEB/C/N treatment is an effective way to improve the wear behavior of pure iron.

Corrosion and wear behaviors of boronized AISI 316L stainless steel

NASA Astrophysics Data System (ADS)

Kayali, Yusuf; Büyüksaǧiş, Aysel; Yalçin, Yılmaz

2013-09-01

In this study, the effects of a boronizing treatment on the corrosion and wear behaviors of AISI 316L austenitic stainless steel (AISI 316L) were examined. The corrosion behavior of the boronized samples was studied via electrochemical methods in a simulation body fluid (SBF) and the wear behavior was examined using the ball-on-disk wear method. It was observed that the boride layer that formed on the AISI 316L surface had a flat and smooth morphology. Furthermore, X-ray diffraction analyses show that the boride layer contained FeB, Fe2B, CrB, Cr2B, NiB, and Ni2B phases. Boride layer thickness increased with an increasing boronizing temperature and time. The boronizing treatment also increased the surface hardness of the AISI 316L. Although there was no positive effect of the coating on the corrosion resistance in the SBF medium. Furthermore, a decrease in the friction coefficient was recorded for the boronized AISI 316L. As the boronizing temperature increased, the wear rate decreased in both dry and wet mediums. As a result, the boronizing treatment contributed positively to the wear resistance by increasing the surface hardness and by decreasing the friction coefficient of the AISI 316L.

Hydrostatic pressure study on high temperature superconductors: HgBa(2)Casb(m-1)Cu(m)O(2m+2+delta) (m = 1 to 6) and (Cu,C)Ba(2)Ca(m-1)Cu(m)O(2m+3) (m = 3 and 4)

NASA Astrophysics Data System (ADS)

Cao, Yong

1998-12-01

Over the last decade, numerous extensive as well as intensive experimental and theoretical investigations have been carried out since the great discovery of high temperature superconductivity (HTSy) in cuprate superconductors Lasb{2-x}Basb{x}CuOsb4,\\ YBasb2Cusb2Osb{7-delta} and other compounds. Although there is still no widely accepted microscopic theory on the mechanism responsible for such high superconducting transition temperatures (Tsb{c}), systematic trends of the evolution of HTSy with various parameters have been studied and analyzed. One of them is the universal inverse parabolic correlation between the Tsb{c} and the number of carriers per CuOsb2 plane (n) in various cuprate superconductors. The high pressure technique provides a clean way to change the distance between atoms without causing the side effects typical of chemical doping, and thus has long been used to test and provide guidance for theoretical models, as well as give hints about the synthesis of compounds with higher Tsb{c}. Therefore, we have done a systematic study on the pressure effect on Tsb{c} of two homologous superconducting compound series: HgBasb2Casb{m-1}Cusb{m}Osb{2m+2+delta} (Hg-12(m-1)m) (m = 1 to 6) and (Cu,C)Basb2Casb{m-1}Cusb{m}Osb{2m+3+delta} ((Cu,C)-12(m-1)m) (m = 3 and 4). Several factors which influence the hydrostatic pressure effect on Tsb{c} have been systematically analyzed. They include the n, the type of charge reservoir layer, and the number of CuOsb2 layers per unit cell (m). We came to several conclusion: (1) The inverse parabolic Tsb{c}(n) correlation and its universal parameters are valid only under conditions more restrictive than originally expected, and the rigid band model may not hold for some cuprate superconductors under pressure. (2) The pressure coefficient (dTsb{c}/dP) may have a different dependence on n. The compounds with Cu-O chains in their charge reservoir usually show a large linear variation of dTsb{c}/dP with n, while no significant dependence is observed on other compounds without the Cu-O chain structure. Therefore, the Cu-O chain might be the main source of pressure-induced charge transfer. (3) The dTsb{c}/dP at nearly optimally doped state dTsb{c}sp{max}/dP, which are almost the same for the m = 1-3 members of Hg-12(m-1)m series, show a step-like drop to about one half of the original values as m = 4, and stay close to that value as m = 5 and 6. This observation is attributed to the inhomogeneous carrier distribution and pressure-induced redistribution of carriers between inner (planar) and outer (pyramidal) CuOsb2 layers. The compounds with m ≥ 4, unlike the first three members, have a large inhomogeneous carrier distribution, and this carrier inhomogeneity is enhanced under pressure. We believe these observations will provide useful information for the development of a microscopic theory on HTSy.

Low temperature InP /Si wafer bonding using boride treated surface

NASA Astrophysics Data System (ADS)

Huang, Hui; Ren, Xiaomin; Wang, Wenjuan; Song, Hailan; Wang, Qi; Cai, Shiwei; Huang, Yongqing

2007-04-01

An approach for InP /Si wafer bonding based on boride-solution treatment was presented. The bonding energy is higher than the InP fracture energy by annealing at 280°C. An In0.53Ga0.47As/InP multiple-quantum-well (MQW) structure grown on InP was transferred onto Si substrate via the bonding process. X-ray diffraction and photoluminescence reveal that crystal quality of the bonded MQW was preserved. A thin B2O3-POx-SiO2 oxide layer of about 28nm thick at the bonding interface was detected. X-ray photoelectron spectroscopy and Raman analyses indicate that the formation of oxygen bridging bonds by boride treatment is responsible for the strong fusion obtained at such low temperature.

Superconducting and Normal State Properties of OsB2*

NASA Astrophysics Data System (ADS)

Singh, Yogesh; Niazi, A.; Zong, X.; Suh, B. J.; Vannette, M. W.; Prozorov, R.; Johnston, D. C.

2007-03-01

OsB2 is a layered superhard metallic material that was found to superconduct below Tc= 2.1 K.^1 We report the first detailed measurements of the static and dynamic magnetic susceptibilities χ, electrical resistivity, heat capacity Cp, penetration depth, and ^11B NMR on OsB2 to characterize its superconducting and normal state properties. The results confirm that OsB2 is a bulk superconductor below Tc= 2.1 K@. Its properties can be described by a close to weak-coupling s-wave BCS model with an electron-phonon coupling constant λ= 0.4--0.5, δ(0)/(kBTc) 1.9, a small Ginzburg-Landau parameter κ of order 5 or less, and a small zero-temperature critical magnetic field of roughly 500 Oe. The ^11B NMR measurements in the normal state show a nuclear spin-lattice relaxation time T1= 2.1 s at room temperature and a Korringa law with T1T = 610 s.K at lower T, and a correspondingly small T-independent Knight shift. These results indicate a small s character of the conduction electron wave function at the B site at the Fermi level. Our results will be compared to corresponding data for MgB2.1. J. K. Vandenberg et al., Mater. Res. Bull. 10, 889 (1975).^*Supported by the USDOE under Contract No. W-7405-Eng-82. Permanent address: Dept. Phys., The Catholic Univ. Korea.

Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB2 and IrB2

NASA Astrophysics Data System (ADS)

Zhang, R. F.; Legut, D.; Wen, X. D.; Veprek, S.; Rajan, K.; Lookman, T.; Mao, H. K.; Zhao, Y. S.

2014-09-01

The energetically most stable orthorhombic structure of OsB2 and IrB2 is dynamically stable for OsB2 but unstable for IrB2. Both diborides have substantially lower shear strength in their easy slip systems than their metal counterparts. This is attributed to an easy sliding facilitated by out-of-plane weakening of metallic Os-Os bonds in OsB2 and by an in-plane bond splitting instability in IrB2. A much higher shear resistance of Os-B and B-B bonds than Os-Os ones is found, suggesting that the strengthened Os-B and B-B bonds are responsible for hardness enhancement in OsB2. In contrast, an in-plane electronic instability in IrB2 limits its strength. The electronic structure of deformed diborides suggests that the electronic instabilities of 5d orbitals are their origin of different bond deformation paths. Neither IrB2 nor OsB2 can be intrinsically superhard.

Phase formation and chemical phase equilibria in aqueous-based systems pertinent to waste-management: calcium oxide-alluminum oxide-borate-water, calcium oxide-lead oxide-phosphate-water and calcium oxide-arsenate-water

NASA Astrophysics Data System (ADS)

Bothe, James Vincent, Jr.

This thesis explores three aqueous-based systems that have importance in the area of waste-management: (1) CaO-Alsb2Osb3-Bsb2Osb3-Hsb2O, (2) CaO-PbO-Psb2Osb5-Hsb2O and (3) CaO-Assb2Osb5-Hsb2O. More specifically, the objective of this research is to identify various precipitated compounds that can effectively immobilize certain elements that either directly or indirectly have an adverse effect on the environment. In the first quaternary system, CaO-Alsb2Osb3-Bsb2Osb3-Hsb2O, boron is the element desired to be ``fixed'' because ``free'' boron is the cause of delayed hardening in cement paste intended for the encapsulation of nuclear waste. Soluble boron also causes the cement paste to prematurely set, a phenomenon called ``flash-set.'' Isothermal calorimetry was used to track the progress of tricalcium aluminate hydration in the presence of boric acid and Ca(OH)sb2 and revealed the presence of a pronounced induction period, the length of which varied with both temperature and boric acid concentration. It was determined that a diffusion barrier, most likely an amorphous calcium borate, deposited onto the active anhydrous tricalcium aluminate grains inhibiting further hydration. Also, under certain conditions, the precipitation of crystalline 4CaO{*}Alsb2Osb3{*}1/2Bsb2Osb3{*}12Hsb2O may be responsible for the observed flash-set due to its flat, plate-like morphology. Another quaternary hydrate, 6CaO{*}Alsb2Osb3{*}2Bsb2Osb3{*}39Hsb2O (boro-ettringite) was also synthesized during this research and crystallized as hexagonal prisms. In contrast to the fast crystallization of 4CaO{*}Alsb2Osb3{*}1/2Bsb2Osb3{*}12Hsb2O, boro-ettringite was observed to form slowly and in stages with the precipitation of the transient phase CaO-Bsb2Osb3{*}6Hsb2O preceding it. Further investigation of these two hydrates lead to the construction of a quaternary phase diagram and to the determination of their solubility products (pKsp = -logKsp), which were determined to be 44.23 for boro-ettringite and 28.51 for 4CaO{*}Alsb2Osb3{*}1/2Bsb2Osb3{*}12Hsb2O. The formation of a solid-solution series between the two apatites, Casb{10}(POsb4)sb6(OH)sb2 and Pbsb{10}(POsb4)sb6(OH)sb2, under ambient conditions and using only oxide starting materials was studied. It was observed that under those conditions, a very limited range of miscibility occurred resulting in the formation of the quaternary apatite, Pbsb{x}Casb{10-x}(POsb4)sb6(OH)sb2 where 5≤ x<6. The ternary system, CaO-Assb2Osb5-Hsb2O, was also studied under ambient conditions in order to identify a potential host compound suitable for the stabilization of soluble arsenic. Analyses of the solid precipitates and their saturated solutions have revealed the following compounds along with their solubility products (pKsp = -logKsp): Casb4(OH)sb2(AsOsb4)sb2{*}4Hsb2O (29.20), Casb5(AsOsb4)sb3OH (38.04), Casb3(AsOsb4)sb2{*}3{2/3}Hsb2O (21.00), Casb3(AsOsb4)sb2{*}4{1/4}Hsb2O (21.00), Casb5Hsb2(AsOsb4)sb4{*}9Hsb2O-ferrarisite (31.49), Casb5Hsb2(AsOsb4)sb4{*}9Hsb2O-guerinite (30.69), and CaHAsOsb4{*}Hsb2O (4.79). The conditions under which the hydrates Casb4(OH)sb2(AsOsb4)sb2{*}4Hsb2O and Casb5(AsOsb4)sb3OH (arsenate-apatite) precipitated were determined to be best in terms of immobilizing soluble arsenic. Both are highly insoluble and are associated with the lowest concentrations of dissolved arsenic under equilibrium conditions. However, the conditions under which they preferentially form are slightly different. Casb4(OH)sb2(AsOsb4)sb2{*}4Hsb2O was observed to form consistently in the presence of magnesium impurity, whereas the arsenate-apatite formed phase-pure only in the absence of magnesium impurity. This can be advantageous in the sense that the arsenate ion is assured to be stabilized via the precipitation of either one or the other, making the presence of magnesium impurity inconsequential under those conditions which precipitate these two stable hydrates.

An investigation of the moisture sorption and permeability properties of mill-fabricated oriented strandboard

NASA Astrophysics Data System (ADS)

Timusk, Paul Christopher

This thesis brings the disciplines of Building Science and Wood Science together in the study of the moisture-related properties of oriented strand board (OSB). Using controlled mill-manufactured panels specifically made for this project, this research reveals how the sorption and permeance properties of OSB are affected by several variables including production parameters and physical panel properties, moisture-history, and relative humidity exposure. Since OSB varies in composition through its thickness, this study isolated and tested various core and surface components. Permeability and sorption properties of individual OSB layers, intact panel sections, and panel sections that had undergone cyclic wetting and drying or relative humidity cycling prior to testing, were evaluated. After laboratory testing and analysis, a set of OSB permeance and sorption values were entered into the material database of a finite-element hygrothermal computer modeling program. Relying on this data, a series of hygrothermal wall simulations were carried out using standard wall sections exposed to various climate conditions found throughout North America. These simulations revealed that the results vary widely depending upon the permeance and sorption values used. Thus the common practice of characterizing a range of OSB products with various moisture histories by using a single permeance or sorption value may not be wise.

Feedback Regulation of ABA Signaling and Biosynthesis by a bZIP Transcription Factor Targets Drought-Resistance-Related Genes1[OPEN

PubMed Central

Tang, Ning; Yang, Jun; Peng, Lei; Ma, Siqi; Xu, Yan; Li, Guoliang

2016-01-01

The OsbZIP23 transcription factor has been characterized for its essential role in drought resistance in rice (Oryza sativa), but the mechanism is unknown. In this study, we first investigated the transcriptional activation of OsbZIP23. A homolog of SnRK2 protein kinase (SAPK2) was found to interact with and phosphorylate OsbZIP23 for its transcriptional activation. SAPK2 also interacted with OsPP2C49, an ABI1 homolog, which deactivated the SAPK2 to inhibit the transcriptional activation activity of OsbZIP23. Next, we performed genome-wide identification of OsbZIP23 targets by immunoprecipitation sequencing and RNA sequencing analyses in the OsbZIP23-overexpression, osbzip23 mutant, and wild-type rice under normal and drought stress conditions. OsbZIP23 directly regulates a large number of reported genes that function in stress response, hormone signaling, and developmental processes. Among these targets, we found that OsbZIP23 could positively regulate OsPP2C49, and overexpression of OsPP2C49 in rice resulted in significantly decreased sensitivity of the abscisic acid (ABA) response and rapid dehydration. Moreover, OsNCED4 (9-cis-epoxycarotenoid dioxygenase4), a key gene in ABA biosynthesis, was also positively regulated by OsbZIP23. Together, our results suggest that OsbZIP23 acts as a central regulator in ABA signaling and biosynthesis, and drought resistance in rice. PMID:27325665

Electronic and elastic properties of new semiconducting oP(12)-type RuB(2) and OsB(2).

PubMed

Hao, Xianfeng; Xu, Yuanhui; Gao, Faming

2011-03-30

Using first-principles total energy calculations we investigate the structural, elastic and electronic properties of new hypothetical oP(12)-type phase RuB(2) and OsB(2). The calculations indicate that the oP(12)-type phase RuB(2) and OsB(2) are thermodynamically and mechanically stable. Remarkably, the new phases RuB(2) and OsB(2) are predicted to be semiconductors, and the appearance of band gaps is ascribed to the enhanced B-B covalent hybridization. Compared to metallic oP(6)-type RuB(2) and OsB(2) phases, the new phases possess similar mechanical properties and hardness. The combination of the probability of tunable electronic properties, strong stiffness and high hardness make RuB(2) and OsB(2) attractive and interesting for advanced applications. © 2011 IOP Publishing Ltd

Investigation of the fracture mechanics of boride composites

NASA Technical Reports Server (NTRS)

Kaufman, L.; Clougherty, E. V.; Nesor, H.

1971-01-01

Fracture energies of WC-6Co, Boride 5 (ZrB2+SiC), Boride 8(ZrB2+SiC+C) and Boride 8-M2(ZrB2+SiC+C) were measured by slow bend and impact tests of notched charpy bars. Cobalt bonded tungsten carbide exhibited impact energies of 0.76 ft-lb or 73.9 in-lb/square inch. Boride 5 and the Boride 8 exhibit impact energies one third and one quarter of that observed for WC-6Co comparing favorably with measurements for SiC and Si3N4. Slow bend-notched bar-fracture energies for WC-6Co were near 2.6 in-lb/square inch or 1/20 the impact energies. Slow bend energies for Boride 8-M2, Boride 8 and Boride 5 were 58%, 42% and 25% of the value observed for WC-6Co. Fractograph showed differences for WC-6Co where slow bend testing resulted in smooth transgranular cleavage while samples broken by impact exhibited intergranular failures. By contrast the boride fractures showed no distinction based on testing method. Fabrication studies were conducted to effect alteration of the boride composites by alloying and introduction of graphite cloth.

Evolution of enzymatic activity in the enolase superfamily: structure of o-succinylbenzoate synthase from Escherichia coli in complex with Mg2+ and o-succinylbenzoate.

PubMed

Thompson, T B; Garrett, J B; Taylor, E A; Meganathan, R; Gerlt, J A; Rayment, I

2000-09-05

The X-ray structures of the ligand free (apo) and the Mg(2+)*o-succinylbenzoate (OSB) product complex of o-succinylbenzoate synthase (OSBS) from Escherichia coli have been solved to 1.65 and 1.77 A resolution, respectively. The structure of apo OSBS was solved by multiple isomorphous replacement in space group P2(1)2(1)2(1); the structure of the complex with Mg(2+)*OSB was solved by molecular replacement in space group P2(1)2(1)2. The two domain fold found for OSBS is similar to those found for other members of the enolase superfamily: a mixed alpha/beta capping domain formed from segments at the N- and C-termini of the polypeptide and a larger (beta/alpha)(7)beta barrel domain. Two regions of disorder were found in the structure of apo OSBS: (i) the loop between the first two beta-strands in the alpha/beta domain; and (ii) the first sheet-helix pair in the barrel domain. These regions are ordered in the product complex with Mg(2+)*OSB. As expected, the Mg(2+)*OSB pair is bound at the C-terminal end of the barrel domain. The electron density for the phenyl succinate component of the product is well-defined; however, the 1-carboxylate appears to adopt multiple conformations. The metal is octahedrally coordinated by Asp(161), Glu(190), and Asp(213), two water molecules, and one oxygen of the benzoate carboxylate group of OSB. The loop between the first two beta-strands in the alpha/beta motif interacts with the aromatic ring of OSB. Lys(133) and Lys(235) are positioned to function as acid/base catalysts in the dehydration reaction. Few hydrogen bonding or electrostatic interactions are involved in the binding of OSB to the active site; instead, most of the interactions between OSB and the protein are either indirect via water molecules or via hydrophobic interactions. As a result, evolution of both the shape and the volume of the active site should be subject to few structural constraints. This would provide a structural strategy for the evolution of new catalytic activities in homologues of OSBS and a likely explanation for how the OSBS from Amycolaptosis also can catalyze the racemization of N-acylamino acids [Palmer, D. R., Garrett, J. B., Sharma, V., Meganathan, R., Babbitt, P. C., and Gerlt, J. A. (1999) Biochemistry 38, 4252-4258].

An XPS study of the adherence of refractory carbide, silicide, and boride RF-sputtered wear-resistant coatings. [X-ray Photoelectron Spectroscopy of steel surfaces

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1978-01-01

Radio frequency sputtering was used to deposit refractory carbide, silicide, and boride coatings on 440-C steel substrates. Both sputter etched and pre-oxidized substrates were used and the films were deposited with and without a substrate bias. The composition of the coatings was determined as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. Friction and wear tests were conducted to evaluate coating adherence. In the interfacial region there was evidence that bias may produce a graded interface for some compounds. Biasing, while generally improving bulk film stoichiometry, can adversely affect adherence by removing interfacial oxide layers. Oxides of all film constituents except carbon and iron were present in all cases but the iron oxide coverage was only complete on the preoxidized substrates. The film and iron oxides were mixed in the MoSi2 and Mo2C films but layered in the Mo2B5 films. In the case of mixed oxides, preoxidation enhanced film adherence. In the layered case it did not.

Thiamine pyrophosphate requirement for o-succinylbenzoic acid synthesis in Escherichia coli and evidence for an intermediate.

PubMed Central

Meganathan, R; Bentley, R

1983-01-01

Cell-free extracts of various strains of Escherichia coli synthesize the menaquinone biosynthetic intermediate o-succinylbenzoic acid (OSB) when supplied with chorismic acid, 2-ketoglutaric acid, and thiamine pyrophosphate (TPP). To assay for OSB synthesis, 2-[U-14C]ketoglutaric acid was used as substrate, and the synthesized OSB was examined by radiogas chromatography (as the dimethyl ester). [U-14C]Shikimic acid also gave rise to radioactive OSB if the cofactors necessary for enzymatic conversion to chorismic acid were added. Use of 2-[1-14C]ketoglutaric acid does not give rise to labeled OSB. In the absence of TPP during the incubations, OSB synthesis was much reduced; these observations are consistent with the proposed role for the succinic semialdehyde-TPP anion as the reagent adding to chorismic acid. Extracts of cells from menC and menD mutants did not form OSB separately, but did so in combination. There was evidence for formation of a product, X, by extracts of a menC mutant incubated with chorismic acid, TPP, and 2-ketoglutaric acid; X was converted to OSB by extracts of a menD mutant. It appears that the intermediate, X, is formed by one gene product and converted to OSB by the second gene product. PMID:6337125

Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krivezhenko, Dina S., E-mail: dinylkaa@yandex.ru; Drobyaz, Ekaterina A., E-mail: ekaterina.drobyaz@yandex.ru; Bataev, Ivan A., E-mail: ivanbataev@ngs.ru

2015-10-27

An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to anmore » enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.« less

Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

NASA Astrophysics Data System (ADS)

Krivezhenko, Dina S.; Drobyaz, Ekaterina A.; Bataev, Ivan A.; Chuchkova, Lyubov V.

2015-10-01

An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to an enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.

First-principles calculations for elastic properties of OsB 2 under pressure

NASA Astrophysics Data System (ADS)

Yang, Jun-Wei; Chen, Xiang-Rong; Luo, Fen; Ji, Guang-Fu

2009-11-01

The structure, elastic properties and elastic anisotropy of orthorhombic OsB 2 are investigated by density functional theory method with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation (GGA) as well as local density approximation (LDA). The obtained structural parameters, elastic constants, elastic anisotropy and Debye temperature for OsB 2 under pressure are consistent with the available experimental data and other theoretical results. It is found that the elastic constants, bulk modulus and Debye temperature of OsB 2 tend to increase with increasing pressure. It is predicted that OsB 2 is not a superhard material from our calculations.

Oxygen interaction with hexagonal OsB 2 at high temperature

DOE PAGES

Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; ...

2016-08-10

The stability of ReB 2-type hexagonal OsB 2 powder at high temperature with oxygen presence has been studied by thermogravimetric analysis, differential scanning calorimetry, SEM, EDS, and high-temperature scanning transmission electron microscopy and XRD. Results of the study revealed that OsB 2 ceramics interact readily with oxygen present in reducing atmosphere, especially at high temperature and produces boric acid, which decomposes on the surface of the powder resulting in the formation of boron vacancies in the hexagonal OsB 2 lattice as well as changes in the stoichiometry of the compound. It was also found that under low oxygen partial pressure,more » sintering of OsB 2 powders occurred at a relatively low temperature (900°C). Finally, hexagonal OsB 2 ceramic is prone to oxidation and it is very sensitive to oxygen partial pressures, especially at high temperatures.« less

Oxygen interaction with hexagonal OsB 2 at high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina

The stability of ReB 2-type hexagonal OsB 2 powder at high temperature with oxygen presence has been studied by thermogravimetric analysis, differential scanning calorimetry, SEM, EDS, and high-temperature scanning transmission electron microscopy and XRD. Results of the study revealed that OsB 2 ceramics interact readily with oxygen present in reducing atmosphere, especially at high temperature and produces boric acid, which decomposes on the surface of the powder resulting in the formation of boron vacancies in the hexagonal OsB 2 lattice as well as changes in the stoichiometry of the compound. It was also found that under low oxygen partial pressure,more » sintering of OsB 2 powders occurred at a relatively low temperature (900°C). Finally, hexagonal OsB 2 ceramic is prone to oxidation and it is very sensitive to oxygen partial pressures, especially at high temperatures.« less

Photovoltaic cell

DOEpatents

Gordon, Roy G.; Kurtz, Sarah

1984-11-27

In a photovoltaic cell structure containing a visibly transparent, electrically conductive first layer of metal oxide, and a light-absorbing semiconductive photovoltaic second layer, the improvement comprising a thin layer of transition metal nitride, carbide or boride interposed between said first and second layers.

Heterometallic and homometallic complexes containing bifunctional ligands and their application in high-temperature oxide superconductor materials

NASA Astrophysics Data System (ADS)

Breeze, Steven R.

We have been interested in the development of soluble precursors for the production of YBasb2Cusb3Osb{7-delta} and Bisb2(Ca,Sr)sbn+1CusbnOsb(2n + 4) + delta, superconductor materials. Several heterometallic and homometallic complexes containing the constituent metals of these superconductors and bifunctional ligands such as aminoalcohols, acetates and thioethers have been isolated and structurally characterized. The thermal decomposition properties and magnetic properties of some of these compounds have been investigated. The first ligand system investigated involved 1,3-bis(dimethylamino)-2-propanol (bdmapH). By varying the ratio of bdmapH, Cu(OCHsb3)sb2, and M(Osb2CCFsb3)sb2 (M = Ca, Sr) several heterometallic complexes have been obtained, including Srsb2Cusb2(bdmap)sb4(Osb2CCFsb3)sb4, CaCu(bdmap)sb2(Osb2CCFsb3)sb3(Hsb2O), Srsb2Cusb4(bdmap)sb6-(Osb2CCFsb3)sb4(musb 3-OH)sb2(THF)sb2 and SrCusb2(bdmap)sb3(Osb2CCFsb3)sb3(THF). With the exception of Srsb2Cusb4(bdmap)sb6(Osb2CCFsb3)sb4(musb 3-OH)sb2(THF)sb2, these compounds thermally decompose to form mixtures of fluorides and oxides. An analogous acetate compound SrCusb2(bdmap)sb3(Osb2CCHsb3)sb3(THF) has been produced, which forms the corresponding oxide at high temperature. A bismuth dimer, Bisb2(bdmap)sb2(Osb2CCHsb3)sb4(Hsb2O), has also been obtained. Superconducting powder of the Bisb2Srsb2CaCusb2Osb{8 + delta} and epitaxial superconducting films of the YBasb2Cusb3Osb{7-delta} superconductor have been produced using the bdmap and acetate ligands as cross-linking reagents. The second ligand system investigated involved di-2-pyridylmethanediol. Only homonuclear complexes have been obtained by using this ligand, including the mononuclear compound Cu ((2-py)sb2CO(OH)) sb2(HOsb2CCH sb3)sb2*CHsb2Clsb2, the tetranuclear compound Cusb4 ((2-py)sb2CO(OH)) sb2(Osb2CCHsb 3)sb6(Hsb2O)sb2*CHsb2Clsb2, and the bismuth dimer Bisb2 ((2-py)sb2CO(OH)) sb2(Osb 2CCFsb3)sb4*(THF)sb2. The tetranuclear Cusb4 compound was found to be dominated by ferromagnetic exchanges. The third ligand system examined involved 2,2sp'-thiodiethanol (tdeHsb2). Heterometallic complexes Prsb2Cusb4(tde)sb3(tdeH)sb2(hfacac)sb4(musb6 -O) and Basb2Cusb2(tdeH)sb4(hfacac)sb4 have been obtained using this ligand. The six metal centers in Prsb2Cusb4(tde)sb3(tdeH)sb2(hfacac)sb4(musb6-O) are arranged in a octahedron and are linked by musb6-oxide and 2,2sp'-thiodiethanolato ligands. A metallomacrocyclic Cusb4 compound, Cusb4(tde)sb2(hfacac)sb4 has been produced. Attempts have been made to produce bismuthine complexes with an amino or pyridyl functional group that can coordinate to copper. The reaction of 4-Li-Csb6Hsb4CHsb2N(2-PY)sb2 with BiClsb3 produces the compound BispIII (p-Csb6Hsb4CHsb2N(2-py)sb2rbracksb3. The ability of this compound to coordinate CuClsb2 has been investigated. The complex BispV (p-Csb6Hsb4CHsb2N(2-py)sb2rbracksb3(Osb2CCHsb3)sb2 has also been produced.

Bacillus anthracis o-succinylbenzoyl-CoA synthetase: reaction kinetics and a novel inhibitor mimicking its reaction intermediate †

PubMed Central

Tian, Yang; Suk, Dae-Hwan; Cai, Feng; Crich, David; Mesecar, Andrew D.

2009-01-01

O-succinylbenzoyl-CoA (OSB-CoA) synthetase (EC 6.2.1.26) catalyzes the ATP-dependent condensation of o-succinylbenzoate (OSB) and CoA to form OSB-CoA, the fourth step of the menaquinone biosynthetic pathway in Bacillus anthracis. Gene knockout studies have highlighted this enzyme as a potential target for the discovery of new antibiotics. Here we report the first studies on the kinetic mechanism of B. anthracis OSB-CoA synthetase, classifying it as an ordered Bi Uni Uni Bi ping-pong mechanism. Through a series of pre-steady-state and steady-state kinetic studies in conjunction with direct-binding studies, it is demonstrated that CoA, the last substrate to bind, strongly activates the first half-reaction after the first round of turnover. The activation of the first-half reaction is most likely achieved by CoA stabilizing conformations of the enzyme in the ‘F’ form, which slowly isomerize back to the E form. Thus, the kinetic mechanism of OSB-CoA synthetase may be more accurately described as an ordered Bi Uni Uni Bi Iso ping-pong mechanism. The substrate specificity of OSB-CoA synthetase was probed using a series of OSB analogs with alterations in the carboxylate groups. OSB-CoA shows a strong preference for OSB over all of the analogs tested as none were active except 4-(2-trifluoromethylphenyl)-4-oxobutyric acid which exhibited a 100-fold decrease in kcat/Km. Based on an understanding of OSB-CoA synthetase’s kinetic mechanism and substrate specificity, a reaction intermediate analog of OSB-AMP, 5’-O-(N-(2-trifluoromethylphenyl)-4-oxobutyl) adenosine sulfonamide (TFMP-butyl-AMS), was designed and synthesized. This inhibitor was found to be an uncompetitive inhibitor to CoA and a mixed-type inhibitor to ATP and OSB with low micromolar inhibition constants. Collectively, these results should serve as an important forerunner to more detailed and extensive inhibitor design studies aimed at developing lead compounds against the OSB-CoA synthetase class of enzymes. PMID:18973344

Bacillus anthracis o-succinylbenzoyl-CoA synthetase: reaction kinetics and a novel inhibitor mimicking its reaction intermediate.

PubMed

Tian, Yang; Suk, Dae-Hwan; Cai, Feng; Crich, David; Mesecar, Andrew D

2008-11-25

o-Succinylbenzoyl-CoA (OSB-CoA) synthetase (EC 6.2.1.26) catalyzes the ATP-dependent condensation of o-succinylbenzoate (OSB) and CoA to form OSB-CoA, the fourth step of the menaquinone biosynthetic pathway in Bacillus anthracis. Gene knockout studies have highlighted this enzyme as a potential target for the discovery of new antibiotics. Here we report the first studies on the kinetic mechanism of B. anthracis OSB-CoA synthetase, classifying it as an ordered bi uni uni bi ping-pong mechanism. Through a series of pre-steady-state and steady-state kinetic studies in conjunction with direct binding studies, it is demonstrated that CoA, the last substrate to bind, strongly activates the first half-reaction after the first round of turnover. The activation of the first half-reaction is most likely achieved by CoA stabilizing conformations of the enzyme in the "F" form, which slowly isomerize back to the E form. Thus, the kinetic mechanism of OSB-CoA synthetase may be more accurately described as an ordered bi uni uni bi iso ping-pong mechanism. The substrate specificity of OSB-CoA synthetase was probed using a series of OSB analogues with alterations in the carboxylate groups. OSB-CoA shows a strong preference for OSB over all of the analogues tested as none were active except 4-[2-(trifluoromethyl)phenyl]-4-oxobutyric acid which exhibited a 100-fold decrease in k(cat)/K(m). On the basis of an understanding of OSB-CoA synthetase's kinetic mechanism and substrate specificity, a reaction intermediate analogue of OSB-AMP, 5'-O-{N-[2-(trifluoromethyl)phenyl]-4-oxobutyl}adenosine sulfonamide (TFMP-butyl-AMS), was designed and synthesized. This inhibitor was found to be an uncompetitive inhibitor to CoA and a mixed-type inhibitor to ATP and OSB with low micromolar inhibition constants. Collectively, these results should serve as an important forerunner to more detailed and extensive inhibitor design studies aimed at developing lead compounds against the OSB-CoA synthetase class of enzymes.

Pressure induced structural phase transition of OsB 2: First-principles calculations

NASA Astrophysics Data System (ADS)

Ren, Fengzhu; Wang, Yuanxu; Lo, V. C.

2010-04-01

Orthorhombic OsB 2 was synthesized at 1000 °C and its compressibility was measured by using the high-pressure X-ray diffraction in a Diacell diamond anvil cell from ambient pressure to 32 GPa [R.W. Cumberland, et al. (2005)]. First-principles calculations were performed to study the possibility of the phase transition of OsB 2. An analysis of the calculated enthalpy shows that orthorhombic OsB 2 can transfer to the hexagonal phase at 10.8 GPa. The calculated results with the quasi-harmonic approximation indicate that this phase transition pressure is little affected by the thermal effect. The calculated phonon band structure shows that the hexagonal P 6 3/ mmc structure (high-pressure phase) is stable for OsB 2. We expect the phase transition can be further confirmed by the experimental work.

Ceramic surfaces, interfaces and solid-state reactions

NASA Astrophysics Data System (ADS)

Heffelfinger, Jason Roy

Faceting, the decomposition of a surface into two or more surfaces of different orientation, is studied as a function of annealing time for ceramic surfaces. Single-crystals of Alsb2Osb3\\ (alpha-Alsb2Osb3 or corundum structure) are carefully prepared and characterized by atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The mechanisms by which the originally smooth vicinal surface transforms into either a hill-and-valley or a terrace-and-step structure have been characterized. The progression of faceting is found to have a series of stages: surface smoothing, nucleation and growth of individual facets, formation of facet domains, coalescence of individual and facet domains and facet coarsening. These stages provide a model for the mechanisms of how other ceramic surfaces may facet into hill-and-valley and terrace-and-step surface microstructures. The well characterized Alsb2Osb3 surfaces provide excellent substrates by which to study the effect of surface structure on thin-film growth. Pulsed-laser deposition was used to grow thin films of yttria stabilized zirconia (YSZ) and Ysb2Osb3 onto annealed Alsb2Osb3 substrates. The substrate surface structure, such as surface steps and terraces, was found to have several effects on thin-film growth. Thin-films grown onto single-crystal substrates serve as a model geometry for studying thin-film solid-state reactions. Here, the reaction sequence and orientation relationship between thin films of Ysb2Osb3 and an Alsb2Osb3 substrate were characterized for different reaction temperatures. In a system were multiple reaction phases can form, the yttria aluminum monoclinic phase (YAM) was found to form prior to formation of other phases in this system. In a second system, a titanium alloy was reacted with single crystal Alsb2Osb3 in order to study phase formation in an intermetallic system. Both Tisb3Al and TiAl were found to form as reaction products and their orientation relationships with the Alsb2Osb3 are discussed.

Stable Analogues of OSB-AMP: Potent Inhibitors of MenE, the o-Succinylbenzoate-CoA Synthetase from Bacterial Menaquinone Biosynthesis

PubMed Central

Lu, Xuequan; Zhou, Rong; Sharma, Indrajeet; Li, Xiaokai; Kumar, Gyanendra; Swaminathan, Subramanyam

2012-01-01

MenE, the o-succinylbenzoate (OSB)-CoA synthetase from bacterial menaquinone biosynthesis, is a promising new antibacterial target. Sulfonyladenosine analogues of the cognate reaction intermediate, OSB-AMP, have been developed as inhibitors of the MenE enzymes from Mycobacterium tuberculosis (mtMenE), Staphylococcus aureus (saMenE) and Escherichia coli (ecMenE). Both a free carboxylate and ketone moiety on the OSB side chain are required for potent inhibitory activity. OSB-AMS (4) is a competitive inhibitor of mtMenE with respect to ATP (Ki = 5.4 ± 0.1 nM) and a non-competitive inhibitor with respect to OSB (Ki = 11.2 ± 0.9 nM). These data are consistent with a bi uni uni bi ping-pong kinetic mechanism for these enzymes. In addition, OSB-AMS inhibits saMenE with Kiapp of 22 ± 8 nM and ecMenE with KiOSB=128±5nM. Putative active site residues, Arg-222, which may interact with the OSB aromatic carboxylate, and Ser-302, which may bind the OSB ketone oxygen, have been identified through computational docking of OSB-AMP with the unliganded crystal structure of saMenE. A pH-dependent interconversion of the free keto acid and lactol forms of the inhibitors is also described, along with implications for inhibitor design. PMID:22109989

Lattice strain of osmium diboride under high pressure and nonhydrostatic stress

NASA Astrophysics Data System (ADS)

Kavner, Abby; Weinberger, Michelle B.; Shahar, Anat; Cumberland, Robert W.; Levine, Jonathan B.; Kaner, Richard B.; Tolbert, Sarah H.

2012-07-01

The lattice strain behavior of osmium diboride—a member of a group of third-row transition metal borides associated with hard/superhard behavior—has been studied using radial diffraction in a diamond anvil cell under high pressure and non-hydrostatic stress. We interpret the average values of the measured lattice strains as a lower-bound to the lattice-plane dependent yield strengths using existing estimates for the elastic constants of OsB2, with a yield strength of 11 GPa at 27.5 GPa of hydrostatic pressure. The measured differential lattice strains show significant plane-dependent anisotropy, with the (101) lattice plane showing the largest differential strain and the (001) lattice plane showing the least strain. At the highest pressure, the a-axis develops a larger compressive strain and supports a larger differential strain than either the b or c axes. This causes an increase in the c/a ratio and a decrease in the a/b ratio especially in the maximum stress direction. The large strength anisotropy of this material points to possible ways to modulate directional mechanical properties by taking advantage of the interplay between aggregate polycrystalline texture with directional mechanical properties.

Stable analogues of OSB-AMP: potent inhibitors of MenE, the o-succinylbenzoate-CoA synthetase from bacterial menaquinone biosynthesis.

PubMed

Lu, Xuequan; Zhou, Rong; Sharma, Indrajeet; Li, Xiaokai; Kumar, Gyanendra; Swaminathan, Subramanyam; Tonge, Peter J; Tan, Derek S

2012-01-02

MenE, the o-succinylbenzoate (OSB)-CoA synthetase from bacterial menaquinone biosynthesis, is a promising new antibacterial target. Sulfonyladenosine analogues of the cognate reaction intermediate, OSB-AMP, have been developed as inhibitors of the MenE enzymes from Mycobacterium tuberculosis (mtMenE), Staphylococcus aureus (saMenE) and Escherichia coli (ecMenE). Both a free carboxylate and a ketone moiety on the OSB side chain are required for potent inhibitory activity. OSB-AMS (4) is a competitive inhibitor of mtMenE with respect to ATP (K(i) =5.4±0.1 nM) and a noncompetitive inhibitor with respect to OSB (K(i) =11.2±0.9 nM). These data are consistent with a Bi Uni Uni Bi Ping-Pong kinetic mechanism for these enzymes. In addition, OSB-AMS inhibits saMenE with K(i)(app) =22±8 nM and ecMenE with K(i)(OSB) =128±5 nM. Putative active-site residues, Arg222, which may interact with the OSB aromatic carboxylate, and Ser302, which may bind the OSB ketone oxygen, have been identified through computational docking of OSB-AMP with the unliganded crystal structure of saMenE. A pH-dependent interconversion of the free keto acid and lactol forms of the inhibitors is also described, along with implications for inhibitor design. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and electronic properties of OsB2 : A hard metallic material

NASA Astrophysics Data System (ADS)

Chen, Z. Y.; Xiang, H. J.; Yang, Jinlong; Hou, J. G.; Zhu, Qingshi

2006-07-01

We calculate the structural and electronic properties of OsB2 using density functional theory with or without taking into account the spin-orbit (SO) interaction. Our results show that the bulk modulus with and without SO interactions are 364 and 365GPa , respectively, both are in good agreement with experiment (365-395GPa) . The evidence of covalent bonding of Os-B, which plays an important role to form a hard material, is indicated both in charge density, atoms in molecules analysis, and density of states analysis. The good metallicity and hardness of OsB2 might suggest its potential application as hard conductors.

The nido-osmaboranes [2,2,2-(CO)(PPh(3))(2)-nido-2-OsB(5)H(9)] and [6,6,6-(CO)(PPh(3))(2)-nido-6-OsB(9)H(13)].

PubMed

Bould, J; Kennedy, J D; Thomas, R L; Rath, N P; Barton, L

2001-11-01

The structural characterization of the osmahexaborane 2-carbonyl-2,2-bis(triphenylphosphine)-nido-2-osmahexaborane(9), [Os(B(5)H(9))(C(18)H(15)P)(2)(CO)], (I), a metallaborane analogue of B(6)H(10), confirms the structure proposed from NMR spectroscopy. The structure of the osmadecaborane 6-carbonyl-6,6-bis(triphenylphosphine)-nido-6-osmadecaborane(13), [Os(B(9)H(13))(C(18)H(15)P)(2)(CO)], (IV), is similarly confirmed. The short basal B-B distance of 1.652 (8) A in (I), not bridged by an H atom, mirrors that in the parent hexaborane(10) [1.626 (4) A].

Plasma enhanced chemical vapor deposition of metalboride interfacial layers as diffusion barriers for nanostructured diamond growth on cobalt containing alloys CoCrMo and WC-Co

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.

This work is a compilation of theory, finite element modeling and experimental research related to the use of microwave plasma enhanced chemical vapor deposition (MPECVD) of diborane to create metal-boride surface coatings on CoCrMo and WC-Co, including the subsequent growth of nanostructured diamond (NSD). Motivation for this research stems from the need for wear resistant coatings on industrial materials, which require improved wear resistance and product lifetime to remain competitive and satisfy growing demand. Nanostructured diamond coatings are a promising solution to material wear but cannot be directly applied to cobalt containing substrates due to graphite nucleation. Unfortunately, conventional pre-treatment methods, such as acid etching, render the substrate too brittle. Thus, the use of boron in a MPECVD process is explored to create robust interlayers which inhibit carbon-cobalt interaction. Furthermore, modeling of the MPECVD process, through the COMSOL MultiphysicsRTM platform, is performed to provide insight into plasma-surface interactions using the simulation of a real-world apparatus. Experimental investigation of MPECVD boriding and NSD deposition was conducted at surface temperatures from 700 to 1100 °C. Several well-adhered metal-boride surface layers were formed: consisting of CoB, CrB, WCoB, CoB and/or W2CoB2. Many of the interlayers were shown to be effective diffusion barriers against elemental cobalt for improving nucleation and adhesion of NSD coatings; diamond on W2CoB2 was well adhered. However, predominantly WCoB and CoB phase interlayers suffered from diamond film delamination. Metal-boride and NSD surfaces were evaluated using glancing-angle x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), cross-sectional scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), micro-Raman spectroscopy, nanoindentation, scratch testing and epoxy pull testing. COMSOL MultiphysicsRTM was used to construct a representation of the MPECVD chamber. Relevant material properties, boundary conditions and adjustable parameters were applied to match the actual experimental set-up. Despite approximations, simulations for the surface temperature and surface accumulation matched well with experimental data. The combination of data from CoCrMo, WC-Co and modeling of the MPECVD process confirms that the use of boron to create metal-boride interlayers is applicable for subsequent nanostructured diamond coatings and that the surface temperature and deposition thickness can be predicted using finite element modeling.

Pt-B System Revisited: Pt2B, a New Structure Type of Binary Borides. Ternary WAl12-Type Derivative Borides.

PubMed

Sologub, Oksana; Salamakha, Leonid; Rogl, Peter; Stöger, Berthold; Bauer, Ernst; Bernardi, Johannes; Giester, Gerald; Waas, Monika; Svagera, Robert

2015-11-16

On the basis of a detailed study applying X-ray single-crystal and powder diffraction, differential scanning calorimetry, and scanning electron microscopy analysis, it was possible to resolve existing uncertainties in the Pt-rich section (≥65 atom % Pt) of the binary Pt-B phase diagram above 600 °C. The formation of a unique structure has been observed for Pt2B [X-ray single-crystal data: space group C2/m, a = 1.62717(11) nm, b = 0.32788(2) nm, c = 0.44200(3) nm, β = 104.401(4)°, RF2 = 0.030]. Within the homogeneity range of "Pt3B", X-ray powder diffraction phase analysis prompted two structural modifications as a function of temperature. The crystal structure of "hT-Pt3B" complies with the hitherto reported structure of anti-MoS2 [space group P63/mmc, a = 0.279377(2) nm, c = 1.04895(1) nm, RF = 0.075, RI = 0.090]. The structure of the new "[Formula: see text]T-Pt3B" is still unknown. The formation of previously reported Pt∼4B has not been confirmed from binary samples. Exploration of the Pt-rich section of the Pt-Cu-B system at 600 °C revealed a new ternary compound, Pt12CuB6-y [X-ray single-crystal data: space group Im3̅, a = 0.75790(2) nm, y = 3, RF2 = 0.0129], which exhibits the filled WAl12-type structure accommodating boron in the interstitial trigonal-prismatic site 12e. The isotypic platinum-aluminum-boride was synthesized and studied. The solubility of copper in binary platinum borides has been found to attain ∼7 atom % Cu for Pt2B but to be insignificant for "[Formula: see text]T-Pt3B". The architecture of the new Pt2B structure combines puckered layers of boron-filled and empty [Pt6] octahedra (anti-CaCl2-type fragment) alternating along the x axis with a double layer of boron-semifilled [Pt6] trigonal prisms interbedded with a layer of empty tetrahedra and tetragonal pyramids (B-deficient α-T[Formula: see text]I fragment). Assuming boron vacancies ordering (space group R3), the Pt12CuB6-y structure exhibits serpentine-like columns of edge-connected boron-filled [Pt6] trigonal prisms running infinitely along the z axis and embedding the icosahedrally coordinated Cu atom. Pt2B, (Pt1-yCuy)2B (y = 0.045), and Pt12CuB6-y (y = 3) behave metallically, as revealed by temperature-dependent electrical resistivity measurements.

Properties of boride-added powder metallurgy magnesium alloys

NASA Astrophysics Data System (ADS)

Tanaka, Atsushi; Yoshimura, Syota; Fujima, Takuya; Takagi, Ken-ichi

2009-06-01

Magnesium alloys with metallic borides, magnesium diboride (MgB2) or aluminum diboride (AlB2), were investigated regarding their mechanical properties, transverse rupture strength (TRS) and micro Vickers hardness (HV). The alloys were made from pure Mg, Al and B powders by mechanical alloying and hot pressing to have boride content of between 2.0 and 20 vol%. The alloy with AlB2 exhibited an obvious improvement of HV around a boride content of 6 vol% though the other alloy, with MgB2, did not. TRS showed moderate maxima around the same boride content region for the both alloys. X-ray diffraction measurements indicated an intermetallic compound, Mg17Al12, formed in the alloy with AlB2, which was consistent with its higher hardness.

Thermodynamic properties of OsB under high temperature and high pressure

NASA Astrophysics Data System (ADS)

Chen, Hai-Hua; Li, Zuo; Cheng, Yan; Bi, Yan; Cai, Ling-Cang

2011-09-01

The energy-volume curves of OsB have been obtained using the first-principles plane-wave ultrasoft-pseudopotential density functional theory (DFT) within the generalized gradient approximation (GGA) and local density approximation (LDA). Using the quasi-harmonic Debye model we first analyze the specific heat, the coefficients of thermal expansion as well as the thermodynamic Grüneisen parameter of OsB in a wide temperature range at high pressure. At temperature 300 K, the coefficients of thermal expansion αV by LDA and GGA calculations are 1.67×10 -5 1/K and 2.01×10 -5 1/K, respectively. The specific heat of OsB at constant pressure (volume) is also calculated. Meanwhile, we find that the Debye temperature of OsB increases monotonically with increasing pressure. The present study leads to a better understanding of how the OsB materials respond to pressure and temperature.

Fetoscopic single-layer repair of open spina bifida using a cellulose patch: preliminary clinical experience.

PubMed

Pedreira, Denise A L; Zanon, Nelci; de Sá, Renato A M; Acacio, Gregório L; Ogeda, Edilson; Belem, Teresa M L O U; Chmait, Ramen H; Kontopoulos, Eftichia; Quintero, Ruben A

2014-11-01

To report our preliminary clinical experience in the antenatal correction of open spina bifida (OSB) using a fetoscopic approach and a simplified closure technique. Four fetuses with lumbar-sacral defects were operated in utero from 25 to 27 weeks. Surgeries were performed percutaneously under general anesthesia using three trocars and partial carbon dioxide insufflation. After dissection of the neural placode, the surrounding skin was closed over a cellulose patch using a single continuous stitch. Surgical closure was successful in three of the four cases. All successful cases showed improvement of the hindbrain herniation and no neonatal neurosurgical repair was required in two cases. Delivery occurred between 31 and 33 weeks, and no fetal or neonatal deaths occurred. Ventriculoperitoneal shunting was not needed in two out of the 3 successful cases. Our preliminary experience suggests that definitive fetoscopic repair of OSB is feasible using our innovative surgical technique. A phase I trial for the fetoscopic correction of OSB with this technique is currently being conducted.

Informationally Efficient Multi-User Communication

DTIC Science & Technology

2010-01-01

DSM algorithms, the Op- timal Spectrum Balancing ( OSB ) algorithm and the Iterative Spectrum Balanc- ing (ISB) algorithm, were proposed to solve the...problem of maximization of a weighted rate-sum across all users [CYM06, YL06]. OSB has an exponential complexity in the number of users. ISB only has a...the duality gap min λ1,λ2 D (λ1, λ2) − max P1,P2 f (P1,P2) is not zero. Fig. 3.3 summarizes the three key steps of a dual method, the OSB algorithm

Percutaneous fetoscopic closure of large open spina bifida using a bilaminar skin substitute.

PubMed

Lapa Pedreira, Denise A; Acacio, Gregório L; Gonçalves, Rodrigo T; Sá, Renato Augusto M; Brandt, Reynaldo A; Chmait, Ramen; Kontopoulos, Eftichia; Quintero, Ruben A

2018-01-04

We have previously described our percutaneous fetoscopic technique for the treatment of open spina bifida (OSB). However, approximately 20-30% of OSB defects are too large to allow primary skin closure. We hereby describe a modification of our standard technique using a bilaminar skin substitute to allow closure of such large spinal defects. The aim of this study was to report our clinical experience with the use of a bilaminar skin substitute and a percutaneous fetoscopic technique for the prenatal closure of large spina bifida defects. Surgeries were performed between 24.0 and 28.9 gestational weeks under general anesthesia, using an entirely percutaneous fetoscopic approach with partial CO2 insufflation of the uterine cavity, as previously described. If there was enough skin to be sutured in the midline, only a biocellulose patch was placed over the placode. In cases where skin approximation was not possible, a bilaminar skin substitute (two layers: one silicone and one dermal matrix) was placed over the biocellulose. The surgical site was assessed at birth, and long-term follow-up was performed. Forty-seven consecutive fetuses underwent percutaneous fetoscopic OSB repair. Premature preterm rupture of membranes (PPROM) occurred in 38 (84%), and the mean gestational age at delivery was 32,8 + 2.5 weeks. A bilaminar skin substitute was required in 13 (29%), of which 5 was associated with myeloschisis. In all cases the skin substitute was found at the surgical site, at birth. In 3 (15%) of these cases, postnatal additional repair was needed. In the other 10 cases, the silicone layer detached spontaneously from the dermal matrix (average 25 days after birth), and the lesion healed by secondary-intention. Operating time was significantly longer in cases requiring the bilaminar skin substitute (additional 42 minutes). The subgroup with bilaminar skin substitute had similar PPROM rate and delivery gestational age compared to the one patch group. Complete reversal of hindbrain herniation occurred in 68% of the one patch and in 33% (p < 0.05) of the two patches group. In 4 cases there was no reversal and 3 of them were myeloschisis cases. Large OSB defects may be successfully treated in utero using a bilaminar skin substitute over a biocellulose patch through an entirely percutaneous approach. Although the operating time is longer, surgical outcomes are similar to cases closed primarily. Myeloschisis seems to have a worse prognosis then myelomeningocele cases. PPROM and preterm birth continue to be a challenge. Further experience is needed to assess the risks and benefits of this technique for management of large OSB defects. This article is protected by copyright. All rights reserved.

Anisotropic type-I superconductivity and anomalous superfluid density in OsB2

NASA Astrophysics Data System (ADS)

Bekaert, J.; Vercauteren, S.; Aperis, A.; Komendová, L.; Prozorov, R.; Partoens, B.; Milošević, M. V.

2016-10-01

We present a microscopic study of superconductivity in OsB2, and discuss the origin and characteristic length scales of the superconducting state. From first-principles we show that OsB2 is characterized by three different Fermi sheets, and we prove that this fermiology complies with recent quantum-oscillation experiments. Using the found microscopic properties, and experimental data from the literature, we employ Ginzburg-Landau relations to reveal that OsB2 is a distinctly type-I superconductor with a very low Ginzburg-Landau parameter κ —a rare property among compound materials. We show that the found coherence length and penetration depth corroborate the measured thermodynamic critical field. Moreover, our calculation of the superconducting gap structure using anisotropic Eliashberg theory and ab initio calculated electron-phonon interaction as input reveals a single but anisotropic gap. The calculated gap spectrum is shown to give an excellent account for the unconventional behavior of the superfluid density of OsB2 measured in experiments as a function of temperature. This reveals that gap anisotropy can explain such behavior, observed in several compounds, which was previously attributed solely to a two-gap nature of superconductivity.

Anisotropic type-I superconductivity and anomalous superfluid density in OsB 2

DOE PAGES

Bekaert, Jonas; Vercauteren, S.; Aperis, A.; ...

2016-10-12

Here, we present a microscopic study of superconductivity in OsB 2, and discuss the origin and characteristic length scales of the superconducting state. From first-principles we show that OsB 2 is characterized by three different Fermi sheets, and we prove that this fermiology complies with recent quantum-oscillation experiments. Using the found microscopic properties, and experimental data from the literature, we employ Ginzburg-Landau relations to reveal that OsB 2 is a distinctly type-I superconductor with a very low Ginzburg-Landau parameter κ—a rare property among compound materials. We show that the found coherence length and penetration depth corroborate the measured thermodynamic criticalmore » field. Moreover, our calculation of the superconducting gap structure using anisotropic Eliashberg theory and ab initio calculated electron-phonon interaction as input reveals a single but anisotropic gap. The calculated gap spectrum is shown to give an excellent account for the unconventional behavior of the superfluid density of OsB 2 measured in experiments as a function of temperature. This reveals that gap anisotropy can explain such behavior, observed in several compounds, which was previously attributed solely to a two-gap nature of superconductivity.« less

Features of surface phase formation during case-hardening of iron- and titanium-based alloys

NASA Astrophysics Data System (ADS)

Vintaikin, B. E.; Kamynin, A. V.; Kraposhin, V. S.; Smirnov, A. E.; Terezanova, K. V.; Cherenkova, S. A.; Sheykina, V. I.

2017-11-01

The article provides a detailed analysis of formation features for surface phases in technical iron and Cr20-Ni80 alloy samples that undergo case-hardening at a temperature of 850°C for 2, 4 and 6 hours of saturation in two different environments: acetylene, and molten salt consisting of sodium tetraborate and amorphous boron. We carried out an X-ray phase analysis to determine the phase structure of surface material layers that formed as a result of the case-hardening process. We discovered that after carburising it was possible to detect Fe3C and Fe-α phases on the surface of technical iron samples, and after boriding we found FeB, Fe2B and Fe3B phases; we noted a lack of characteristic Fe-α and Fe-γ peaks on the X-ray diffraction pattern. We detected many different phases in the Cr20-Ni80 alloy after the same type of case-hardening. Titanium oxides appeared after case-hardening of titanium in air at 800°C. We provide data on surface structure of samples subjected to vacuum carburising: over a 2 to 6 hour interval, the layer thickness is a parabolic function of time. When carrying out electrolysis-free liquid boriding, increasing exposure time from 2 to 6 hours alters the thickness of the strengthened layer only slightly, so, when carrying out case-hardening, it is less efficient to increase saturation time in molten salt containing sodium tetraborate and amorphous boron.

Effects of point defect concentrations of the reactive element oxides on the oxidation kinetics of pure Ni and Ni-Cr alloys

NASA Astrophysics Data System (ADS)

Yan, Ruey-Fong

The addition of some reactive element oxides, e.g. Ysb2Osb3 or ZrOsb2, has significant effects, e.g. improvement in scale adhesion and reduction in oxidation rate, on the oxidation behavior of chromia and alumina scale forming alloys at high temperatures. However, there is little agreement about how a small addition of an oxygen-active element can cause such profound effects. It was the goal of this project to study the growth kinetics of an oxide scale when different reactive-element oxides were added to pure Ni and Ni-Cr alloys and, consequently, to aid in clarifying the mechanism of reactive element effects. The oxidation kinetics were measured using a thermogravimetric analysis (TGA) method and the material characterization of oxide scale was conducted. The relationship between point defect structures and oxidation kinetics was discussed. The results in this research showed that Ysb2Osb3 and ZrOsb2 exhibited the reactive element effects on the oxidation behaviors of Ni and Ni-Cr alloys. In addition, the point defect concentrations of the reactive element oxide, Ysb2Osb3, were changed by doping of different valent oxides. The modification of point defect concentrations of the reactive element oxide dispersed phases did change the oxidation kinetics of the pure Ni and Ni-Cr alloys containing Ysb2Osb3. These results indicate that the transport properties of the reactive element oxide dispersed phases are one of the important factors in determining the growth rate of an oxide scale.

Characterization of Escherichia coli men Mutants Defective in Conversion of o-Succinylbenzoate to 1,4-Dihydroxy-2-Naphthoate

PubMed Central

Shaw, Duncan J.; Guest, John R.; Meganathan, Rangaswamy; Bentley, Ronald

1982-01-01

Four independent menaquinone (vitamin K2)-deficient mutants of Escherichia coli, blocked in the conversion of o-succinylbenzoate (OSB) to 1,4-dihydroxy-2-naphthoate (DHNA), were found to represent two distinct classes. Enzymatic complementation was observed when a cell-free extract of one mutant was mixed with extracts of any of the remaining three mutants. The missing enzymes in the two classes were identified by in vitro complementation with preparations of OSB-coenzyme A (CoA) synthetase or DHNA synthase isolated from Mycobacterium phlei. Mutants lacking DHNA synthase (and therefore complementing with M. phlei DHNA synthase) were designated menB, and the mutant lacking OSB-CoA synthetase (and therefore complementing with M. phlei OSB-CoA synthetase) was designated menE. The menB mutants produced only the spirodilactone form of OSB when extracts were incubated with [2,3-14C2]OSB, ATP, and CoA; the OSB was unchanged on incubation with an extract from the menE mutant under these conditions. Experiments with strains lysogenized by a λ men transducing phage (λG68) and transduction studies with phage P1 indicated that the menB and menE genes form part of a cluster of four genes, controlling the early steps in menaquinone biosynthesis, located at 48.5 min in the E. coli linkage map. Evidence was obtained for the clockwise gene order gyrA....menC- 0000100000 0000110000 0011111000 0000111000 0011111000 0001110000 0000110101 0001111111 0001100000 0000100000 0001101100 0011111000 0011000000 0011000000 0111000111 0111101110 -B-D, where the asterisk denotes the uncertain position of menE relative to menC and menB. The transducing phage (λG68) contained functional menB, menC, and menE genes, but only part of the menD gene, and it was designated λ menCB(D). PMID:6754698

Chemosensory irritations and pulmonary effects of acute exposure to emissions from oriented strand board.

PubMed

Gminski, Richard; Marutzky, Rainer; Kevekordes, Sebastian; Fuhrmann, Frank; Bürger, Werner; Hauschke, Dieter; Ebner, Winfried; Mersch-Sundermann, Volker

2011-09-01

Due to the reduction of air change rates in low-energy houses, the contribution to indoor air quality of volatile organic compounds (VOCs) emitting from oriented strand boards (OSB) has become increasingly important. The aim of this study was to evaluate sensory irritations, pulmonary effects and odor annoyance of emissions from OSB in healthy human volunteers compared to clean air. Twenty-four healthy non-smokers were exposed to clean air and OSB emissions for 2 h under controlled conditions in a 48 m(3) test chamber at three different time points: to fresh OSB panels and to the same panels after open storage for 2 and 8 weeks. Chemosensory irritation, exhaled nitric oxide (NO) concentration, eye blink frequency, lung function and subjective perception of irritation of eyes, nose and throat were examined before, during and after exposure. Additionally, olfactory perception was investigated. Total VOC exposure concentrations reached 8.9 ± 0.8 mg/m(3) for the fresh OSB panels. Emissions consisted predominantly of α-pinene, Δ(3)-carene and hexanal. Two-hour exposure to high VOC concentrations revealed no irritating or pulmonary effects. All the subjective ratings of discomfort were at a low level and the medians did not exceed the expression 'hardly at all.' Only the ratings for smell of emissions increased significantly during exposure in comparison to clean air. In conclusion, exposure of healthy volunteers to OSB emissions did not elicit sensory irritations or pulmonary effects up to a VOC concentration of about 9 mg/m(3). Sensory intensity of OSB emissions in the chamber air was rated as 'neutral to pleasant.'

Patient-specific 3D microfluidic tissue model for multiple myeloma.

PubMed

Zhang, Wenting; Lee, Woo Y; Siegel, David S; Tolias, Peter; Zilberberg, Jenny

2014-08-01

In vitro culturing of primary multiple myeloma cells (MMC) has been a major challenge as this plasma cell malignancy depends on the bone marrow environment for its survival. Using a microfluidic platform to emulate the dynamic physiology of the bone marrow microenvironment, we report here a new approach for culturing difficult to preserve primary human MMC. The system uses a three-dimensional ossified tissue to mimic the tumor niche and recapitulate interactions between bone marrow cells and osteoblasts (OSB). To this end, the human fetal OSB cell line hFOB 1.19 was cultured in an eight-chamber microfluidic culture device to facilitate the seeding of mononuclear cells from bone marrow aspirates from three multiple myeloma patients. Optical microscopy, used for real-time monitoring of mononuclear cell interactions with the ossified tissue, confirmed that these are drawn toward the OSB layer. After 3 weeks, cocultures were characterized by flow cytometry to evaluate the amount of expansion of primary MMC (with CD138(+) and CD38(+)CD56(+) phenotypes) in this system. For each of the three patients analyzed, bone marrow mononuclear cells underwent, on an average, 2 to 5 expansions; CD38(+)CD56(+) cells underwent 1 to 3 expansions and CD138(+) cells underwent 2.5 to 4.6 expansions. This approach is expected to provide a new avenue that can facilitate: (1) testing of personalized therapeutics for multiple myeloma patients; (2) evaluation of new drugs without the need for costly animal models; and (3) studying the biology of multiple myeloma, and in particular, the mechanisms responsible for drug resistance and relapse.

Hexagonal OsB 2: Sintering, microstructure and mechanical properties

DOE PAGES

Xie, Zhilin; Lugovy, Mykola; Orlovskaya, Nina; ...

2015-02-07

In this study, the metastable high pressure ReB 2-type hexagonal OsB 2 bulk ceramics was produced by spark plasma sintering. The phase composition, microstructure, and mechanical behavior of the sintered OsB 2 were studied by X-ray diffraction, optical microscopy, TEM, SEM, EDS, and nanoindentation. The produced ceramics was rather porous and contained a mixture of hexagonal (~80 wt.%) and orthorhombic (~20 wt.%) phases as identified by X-ray diffraction and EBSD analysis. Two boron-rich phases, which do not contain Os, were also identified by TEM and SEM/EDS analysis. Nanoindentation measurements yielded a hardness of 31 ± 9 GPa and Young’s modulusmore » of 574 ± 112 GPa, indicating that the material is rather hard and very stiff; but, it is very prone to crack formation and propagation, which is indicative of a very brittle nature of this material. Improvements in the sintering regime are required in order to produce dense, homogeneous and single phase hexagonal OsB 2 bulk ceramics.« less

Crystal structure and phase stability of tungsten borides

NASA Astrophysics Data System (ADS)

Li, Quan; Zhou, Dan; Ma, Yanming; Chen, Changfeng

2013-03-01

We address the longstanding and controversial issue of ground-state structures of technically important tungsten borides using a first-principles structural search method via a particle-swarm optimization (PSO) algorithm. We have explored a large set of stable chemical compositions (convex hull) and clarified the ground-state structures for a wide range of boron concentrations, including W2B, W3B2,WB,W2B3, WB2,W2B5, WB3, and WB4. We further assessed relative stability of various tungsten borides and compared the calculated results with previously reported experimental data. The phase diagram predicted by the presented calculations may serve as a useful guide for synthesis of a variety of tungsten borides. This work was supported by DOE Grant No. DE-FC52-06NA26274.

OSB as substrate for engineered wood flooring

Treesearch

Costel Barbuta; Pierre Blanchet; Alain Cloutier; Vikram Yadama; Eini Lowell

2012-01-01

Oriented strand board (OSB) is a commodity product subject to market fluctuation. Development of a specialty OSB could lead to a better, and more stable, market segment for OSB. It was demonstrated in a previous study (Barbuta et al. in Eur. 1. Wood Prod. 2010), that OSB may be designed to obtain a high bending modulus of elasticity in the parallel direction, close to...

Evolution of enzymatic activity in the enolase superfamily: structural and mutagenic studies of the mechanism of the reaction catalyzed by o-succinylbenzoate synthase from Escherichia coli.

PubMed

Klenchin, Vadim A; Taylor Ringia, Erika A; Gerlt, John A; Rayment, Ivan

2003-12-16

o-Succinylbenzoate synthase (OSBS) from Escherichia coli, a member of the enolase superfamily, catalyzes an exergonic dehydration reaction in the menaquinone biosynthetic pathway in which 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC) is converted to 4-(2'-carboxyphenyl)-4-oxobutyrate (o-succinylbenzoate or OSB). Our previous structural studies of the Mg(2+).OSB complex established that OSBS is a member of the muconate lactonizing enzyme subgroup of the superfamily: the essential Mg(2+) is coordinated to carboxylate ligands at the ends of the third, fourth, and fifth beta-strands of the (beta/alpha)(7)beta-barrel catalytic domain, and the OSB product is located between the Lys 133 at the end of the second beta-strand and the Lys 235 at the end of the sixth beta-strand [Thompson, T. B., Garrett, J. B., Taylor, E. A, Meganathan, R., Gerlt, J. A., and Rayment, I. (2000) Biochemistry 39, 10662-76]. Both Lys 133 and Lys 235 were separately replaced with Ala, Ser, and Arg residues; all six mutants displayed no detectable catalytic activity. The structure of the Mg(2+).SHCHC complex of the K133R mutant has been solved at 1.62 A resolution by molecular replacement starting from the structure of the Mg(2+).OSB complex. This establishes the absolute configuration of SHCHC: the C1-carboxylate and the C6-OH leaving group are in a trans orientation, requiring that the dehydration proceed via a syn stereochemical course. The side chain of Arg 133 is pointed out of the active site so that it cannot function as a general base, whereas in the wild-type enzyme complexed with Mg(2+).OSB, the side chain of Lys 133 is appropriately positioned to function as the only acid/base catalyst in the syn dehydration. The epsilon-ammonium group of Lys 235 forms a cation-pi interaction with the cyclohexadienyl moiety of SHCHC, suggesting that Lys 235 also stabilizes the enediolate anion intermediate in the syn dehydration via a similar interaction.

Identification of delamination failure of boride layer on common Cr-based steels

NASA Astrophysics Data System (ADS)

Taktak, Sukru; Tasgetiren, Suleyman

2006-10-01

Adhesion is an important aspect in the reliability of coated components. With low-adhesion of interfaces, different crack paths may develop depending on the local stress field at the interface and the fracture toughness of the coating, substrate, and interface. In the current study, an attempt has been made to identify the delamination failure of coated Cr-based steels by boronizing. For this reason, two commonly used steels (AISI H13, AISI 304) are considered. The steels contain 5.3 and 18.3 wt.% Cr, respectively. Boriding treatment is carried out in a slurry salt bath consisting of borax, boric acid, and ferrosilicon at a temperature range of 800 950 °C for 3, 5, and 7 h. The general properties of the boron coating are obtained by mechanical and metallographic characterization tests. For identification of coating layer failure, some fracture toughness tests and the Daimler-Benz Rockwell-C adhesion test are used.

Development of high temperature stable Ohmic and Schottky contacts on n-gallium nitride

NASA Astrophysics Data System (ADS)

Khanna, Rohit

In this work the effort was made to towards develop and investigate high temperature stable Ohmic and Schottky contacts for n type GaN. Various borides and refractory materials were incorporated in metallization scheme to best attain the desired effect of minimal degradation of contacts when placed at high temperatures. This work focuses on achieving a contact scheme using different borides which include two Tungsten Borides (namely W2B, W2B 5), Titanium Boride (TiB2), Chromium Boride (CrB2) and Zirconium Boride (ZrB2). Further a high temperature metal namely Iridium (Ir) was evaluated as a potential contact to n-GaN, as part of continuing improved device technology development. The main goal of this project was to investigate the most promising boride-based contact metallurgies on GaN, and finally to fabricate a High Electron Mobility Transistor (HEMT) and compare its reliability to a HEMT using present technology contact. Ohmic contacts were fabricated on n GaN using borides in the metallization scheme of Ti/Al/boride/Ti/Au. The characterization of the contacts was done using current-voltage measurements, scanning electron microscopy (SEM) and Auger Electron Spectroscopy (AES) measurements. The contacts formed gave specific contact resistance of the order of 10-5 to 10-6 Ohm-cm2. A minimum contact resistance of 1.5x10-6 O.cm 2 was achieved for the TiB2 based scheme at an annealing temperature of 850-900°C, which was comparable to a regular ohmic contact of Ti/Al/Ni/Au on n GaN. When some of borides contacts were placed on a hot plate or in hot oven for temperature ranging from 200°C to 350°C, the regular metallization contacts degraded before than borides ones. Even with a certain amount of intermixing of the metallization scheme the boride contacts showed minimal roughening and smoother morphology, which, in terms of edge acuity, is crucial for very small gate devices. Schottky contacts were also fabricated and characterized using all the five boride compounds. The barrier height obtained on n GaN was ˜0-5-0.6 eV which was low compared to those obtained by Pt or Ni. This barrier height is too low for use as a gate contact and they can only have limited use, perhaps, in gas sensors where large leakage current can be tolerated in exchange for better thermal reliability. AlGaN/GaN High Electron Mobility Transistors (HEMTs) were fabricated with Ti/Al/TiB2/Ti/Au source/drain ohmic contacts and a variety of gate metal schemes (Pt/Au, Ni/Au, Pt/TiB2/Au or Ni/TiB 2/Au) and were subjected to long-term annealing at 350°C. By comparison with companion devices with conventional Ti/Al/Pt/Au ohmic contacts and Pt/Au gate contacts, the HEMTs with boride-based ohmic metal and either Pt/Au, Ni/Au or Ni/TiB2/Au gate metal showed superior stability of both source-drain current and transconductance after 25 days aging at 350°C. The need for sputter deposition of the borides causes' problem in achieving significantly lower specific contact resistance than with conventional schemes deposited using e-beam evaporation. The borides also seem to be, in general, good getters for oxygen leading to sheet resistivity issues. Ir/Au Schottky contacts and Ti/Al/Ir/Au ohmic contacts on n-type GaN were investigated as a function of annealing temperature and compared to their more common Ni-based counterparts. The Ir/Au ohmic contacts on n-type GaN with n˜1017 cm-3 exhibited barrier heights of 0.55 eV after annealing at 700°C and displayed less intermixing of the contact metals compared to Ni/Au. A minimum specific contact resistance of 1.6 x 10-6 O.cm2 was obtained for the ohmic contacts on n-type GaN with n˜1018 cm-3 after annealing at 900°C. The measurement temperature dependence of contact resistance was similar for both Ti/Al/Ir/Au and Ti/Al/Ni/Au, suggesting the same transport mechanism was present in both types of contacts. The Ir-based ohmic contacts displayed superior thermal aging characteristics at 350°C. Auger Electron Spectroscopy showed that Ir is a superior diffusion barrier at these moderate temperatures than Ni.

Betting is Loving and Bettors are Predators: A Conceptual Metaphor Approach to Online Sports Betting Advertising.

PubMed

Lopez-Gonzalez, Hibai; Guerrero-Solé, Frederic; Estévez, Ana; Griffiths, Mark

2017-10-30

The legalisation of online gambling in multiple territories has caused a growth in the exposure of consumers to online sports betting (OSB) advertising. While some efforts have been made to understand the visible structure of betting promotional messages, little is known about the latent components of OSB advertisements. The present study sought to address this issue by examining the metaphorical conceptualisation of OSB advertising. A sample of Spanish and British television OSB advertisements from 2014 to 2016 was analysed (N = 133). Following Lakoff and Johnson's conceptual metaphor theory, four main structural metaphors that shaped how OSB advertising can be understood were identified: betting as (1) an act of love, (2) a market, (3) a sport, and (4) a natural environment. In general, these metaphors, which were found widely across 29 different betting brands, facilitated the perception of bettors as active players, with an executive role in the sport events bet upon, and greater control over bet outcomes.

Characterization of mixed-conducting barium cerate-based perovskites for potential fuel cell applications

NASA Astrophysics Data System (ADS)

Mukundan, R.

Chemical modifications of barium cerium gadolinium oxide through the substitution of Bi, Tb, Pr, Nb and Ta were attempted in an effort to increase the p-type or n-type conductivity, and to develop new mixed-conducting electrodes that are chemically compatible with the Ba(Cesb{1-x}Gdsb{x})Osb{3-x/2} electrolyte. The structure, oxygen non-stoichiometry, electronic and ionic-conductivity of several compositions in the doped-barium cerate systems were studied by X-ray diffraction, TGA, DC and AC conductivity, and EMF measurements. The cathodic overpotential of the mixed (electronic/ionic) conducting compositions in this system, on a Ba(Cesb{0.8}Gdsb{0.2})Osb{2.9} electrolyte, were also studied using Current Interruption and AC impedance techniques. The substitution of Bi into Ba(Cesb{0.9}Gdsb{0.1})Osb{2.95} lead to a significant increase in the electronic conductivity, and a total conductivity of about 0.94 S/cm was obtained for Ba(Bisb{0.5}Cesb{0.4}Gdsb{0.1})Osb3 at 800sp°C in air. However, the concentration of oxygen-ion vacancies and hence the ionic conductivity decreased due to the oxidation of Bi to the 5sp{+} state. Compositions in the Ba(Bisb{0.5}Cesb{x}Gdsb{0.5-x})Osb3 system also exhibited significant oxygen non-stoichiometry depending upon the ordering of the B-site cations and the relative concentrations of Ce and Gd. However, the absence of any detectable EMF in the non-stoichiometric compositions implied that the oxygen vacancies are strongly associated with the Bisp{3+} cations. Although highly conductive, chemically stable compositions were prepared in the Ba(Bisb{x}Cesb{y}Gdsb{1-(x+y)})Osb{3-d} system, their ionic conductivities were low. The mixed-conduction properties of Ba(Cesb{1-x}Gdsb{x})Osb{3-d} were enhanced under cathode conditions (600-800sp°C in air) by the substitution of Ce by Tb and Pr. While the substitution of Tb resulted in a decrease in the total conductivity, Pr induced a significant increase in the total conductivity at high Pr levels (≥40 mole%) due to an enhancement of the electronic conductivity. The Ba(Prsb{0.8}Gdsb{0.2})Osb{2.9} sample was found to have the best mixed-conducting properties of all the perovskites evaluated, sigmasb{T}=0.75 S/cm in air at 800sp°C, tsb{H+}=0.15 in a wet argon//dry argon gradient, and tsb{0.2-}≈ 0.05 in a dry air//dry argon gradient. The cathodic overpotentials of the mixed-conducting Pr-doped barium cerates were low, and decreased with increasing ionic and electronic conductivity of the electrode. The lowest overpotential was obtained for the Ba(Prsb{0.8}Gdsb{0.2})Osb{2.9}, cathode, and at low current densities was comparable to that of an optimized porous Pt-electrode. While the substitution of Nb and Ta for Ce lead to an enhancement in the electronic conductivity under reducing conditions associated with the increased reduction of Cesp{4+} to Cesp{3+}, the ionic-conductivity of these perovskites was low. There was no evidence for any protonic conductivity in the 15 mole% Nb and Ta substituted barium cerates. Moreover the anodic overpotential and the anode resistance of these perovskites on a Ba(Cesb{0.8}Gdsb{0.2})Osb{2.9} electrolyte were both high.

Plasma-induced damage of tungsten coatings on graphite limiters

NASA Astrophysics Data System (ADS)

Fortuna, E.; Rubel, M. J.; Psoda, M.; Andrzejczuk, M.; Kurzydowski, K. J.; Miskiewicz, M.; Philipps, V.; Pospieszczyk, A.; Sergienko, G.; Spychalski, M.; Zielinski, W.

2007-03-01

Vaccum plasma sprayed tungsten coatings with an evaporated sandwich Re-W interlayer on graphite limiter blocks were studied after the experimental campaign in the TEXTOR tokamak. The coating morphology was modified by high-heat loads and co-deposition of species from the plasma. Co-deposits contained fuel species, carbon, boron and silicon. X-ray diffractometer phase analysis indicated the coexistence of metallic tungsten and its carbides (WC and W2C) and boride (W2B). In the Re-W layer the presence of carbon was detected in a several micrometres thick zone. In the overheated part of the limiter, the Re-W layer was transformed into a sigma phase.

Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys

PubMed Central

Matsushita, Masafumi

2011-01-01

Bronization and carburization of fine-grain superplastic stainless steel is reviewed, and new experimental results for fine grain Ti88.5Al4.5V3Fe2Mo2 are reported. In superplastic duplex stainless steel, the diffusion of carbon and boron is faster than in non-superplastic duplex stainless steel. Further, diffusion is activated by uniaxial compressive stress. Moreover, non-superplastic duplex stainless steel shows typical grain boundary diffusion; however, inner grain diffusion is confirmed in superplastic stainless steel. The presence of Fe and Cr carbides or borides is confirmed by X-ray diffraction, which indicates that the diffused carbon and boron react with the Fe and Cr in superplastic stainless steel. The Vickers hardness of the carburized and boronized layers is similar to that achieved with other surface treatments such as electro-deposition. Diffusion of boron into the superplastic Ti88.5Al4.5V3Fe2Mo2 alloy was investigated. The hardness of the surface exposed to boron powder can be increased by annealing above the superplastic temperature. However, the Vickers hardness is lower than that of Ti boride. PMID:28824144

Non-Contact Tabletop Mechanical Testing of Ultra-High Temperature Ceramics

DTIC Science & Technology

2012-05-01

class of refractory materials including transition metal borides , carbides and nitrides e.g. ZrB2l HfB2) ZrC, HfC, TaC, HfN and ZrN. They recently...ike oxidizing atmospheres, at very high temperatures Refractory borides like ZrB2 and HfB2 have extremely high melting temperatures (over 3000°C...But borides are very poor in oxidation resistance, due to the nature of thär oxides Non-protective ZrCfe or Hf02 and volatile liquid B203. Addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossain, M. Anwar; Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511; Tanaka, Isao

We studied thermoelectric properties of YB{sub 41}Si{sub 1.3} single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers,more » with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. - Graphical abstract: The growth direction ([510]) was determined for the first time in YB{sub 41}Si{sub 1.3} single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. - Highlights: • We have grown YB{sub 41}Si{sub 1.3} single crystals by the floating zone method. • Growth direction of [510] determined for first time in REB{sub 41}Si{sub 1.2}. • Electrical resistivity was strongly anisotropic with possible enhancement along metal layers. • The obtained power factor along [510] is 3.6 times higher than that along [052].« less

The use of surface layer with boron in friction pairs lubricated by engine oils

NASA Astrophysics Data System (ADS)

Szczypiński-Sala, W.; Lubas, J.

2016-09-01

The aim of the present work is to determine the influence of surface layers with boron and engine oil on the processes of friction and wear in friction pairs. The ring samples with borided surface layer cooperated under test conditions with counterparts made with CuPb30 and AlSn20 bearing alloys. During the tests, the friction pairs were lubricated with 15W/40 Lotos mineral oil and 5W/40 Lotos synthetic oil. The lubrication of friction area with Lotos mineral oil causes the reduction of the friction force, the temperature in the friction area and the wear of the bearing alloys under study, whereas the lubrication with Lotos synthetic oil reduces the changes in the geometrical structure of the cooperating friction pair elements. Lubrication of the friction area in the start-up phase of the friction pair by mineral oil causes faster stabilization of the friction conditions in the contact area than in the cause of lubrication of the friction pair by synthetic oil. The intensity of wear of the AlSn20 bearing alloy cooperating with the borided surface layer is three times smaller than the intensity of use of the CuPb30 alloy bearing.

Synthesis and Characterization of YB4 Ceramics

DTIC Science & Technology

2011-06-24

capa bility at temperatures above 2000°C1 with adequate mechani cal properties and oxidation resistance. Refractory metal borides based on HfB2 and ZrB2...increase in the oxidation resistance was accomplished by the addition of the Group IV VI transition metal borides , which was the result of phase...metal borides for use as materials for ultra high temper ature (UHT) applications. However, for instance, yttrium tet raboride, YB4, appears promising as

Microstructural characterization of Ni-based self-fluxing alloy after selective surface-engineering using diode laser

NASA Astrophysics Data System (ADS)

Chun, Eun-Joon; Park, Changkyoo; Nishikawa, Hiroshi; Kim, Min-Su

2018-06-01

The microstructural characterization of thermal-sprayed Ni-based self-fluxing alloy (Metco-16C®) after laser-assisted homogenization treatment was performed. To this end, a high-power diode laser system was used. This supported the real-time control of the target homogenization temperature at the substrate surface. Non-homogeneities of the macrosegregation of certain elements (C and Cu) and the local concentration of Cr-based carbides and borides in certain regions in the as-sprayed state could be enhanced with the application of homogenization. After homogenization at 1423 K, the hardness of the thermal-sprayed layer was found to have increased by 1280 HV from the as-sprayed state (750 HV). At this homogenization temperature, the microstructure of the thermal-sprayed layer consisted of a lamellar structuring of the matrix phase (austenite and Ni3Si) with fine (<5 μm) carbides and borides (the rod-like phase of Cr5B3, the lumpy phase of M23C6, and the extra-fine phase of M7C3). Despite the formation of several kinds of carbides and borides during homogenization at 1473 K, the lowest hardness level was found to be less than that of the as-sprayed state, because of the liquid-state homogenization treatment without formation of lamellar structuring between austenite and Ni3Si.

[Effectiveness comparison of anatomical single-bundle and over-the-top single-bundle reconstruction of anterior cruciate ligament].

PubMed

Dong, Yu; Chen, Shiyi; Li, Yunxia; Chen, Jiwu; Hua, Yinghui

2011-08-01

To compare the effectiveness of anatomical single-bundle (ASB) and over-the-top single-bundle (OSB) reconstruction of the anterior cruciate ligament (ACL). Between January 2008 and June 2008, 64 patients with ACL injury underwent arthroscopic ACL reconstruction. ASB ACL reconstruction was performed in 28 cases (ASB group) and OSB ACL reconstruction in 36 cases (OSB group). There was no significant difference in gender, age, disease duration, International Knee Documentation Committee (IKDC) score, Lysholm score, and side-to-side difference between 2 groups (P > 0.05). All incisions healed by first intention; no infection or other complications occurred. All cases were followed up 20-24 months (mean, 21.5 months). There were significant differences in the IKDC score, Lysholm score, and the side-to-side difference between last follow-up and preoperation in 2 groups (P < 0.05), but there was no significant difference between 2 groups at last follow-up (P > 0.05). Significant differences were found in negative rate of the pivot shift test between last follow-up and preoperation in ASB group and between 2 groups at last follow-up (P < 0.05), but there was no significant difference between last follow-up and preoperation in OSB group (P > 0.05). The effectiveness of arthroscopic ASB ACL reconstruction is better than that of arthroscopic OSB ACL reconstruction, especially in controlling rotational stability.

Characterisation of titanium-titanium boride composites processed by powder metallurgy techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selva Kumar, M., E-mail: sel_mcet@yahoo.co.in; Chandrasekar, P.; Chandramohan, P.

2012-11-15

In this work, a detailed characterisation of titanium-titanium boride composites processed by three powder metallurgy techniques, namely, hot isostatic pressing, spark plasma sintering and vacuum sintering, was conducted. Two composites with different volume percents of titanium boride reinforcement were used for the investigation. One was titanium with 20% titanium boride, and the other was titanium with 40% titanium boride (by volume). Characterisation was performed using X-ray diffraction, electron probe micro analysis - energy dispersive spectroscopy and wavelength dispersive spectroscopy, image analysis and scanning electron microscopy. The characterisation results confirm the completion of the titanium boride reaction. The results reveal themore » presence of titanium boride reinforcement in different morphologies such as needle-shaped whiskers, short agglomerated whiskers and fine plates. The paper also discusses how mechanical properties such as microhardness, elastic modulus and Poisson's ratio are influenced by the processing techniques as well as the volume fraction of the titanium boride reinforcement. - Highlights: Black-Right-Pointing-Pointer Ti-TiB composites were processed by HIP, SPS and vacuum sintering. Black-Right-Pointing-Pointer The completion of Ti-TiB{sub 2} reaction was confirmed by XRD, SEM and EPMA studies. Black-Right-Pointing-Pointer Hardness and elastic properties of Ti-TiB composites were discussed. Black-Right-Pointing-Pointer Processing techniques were compared with respect to their microstructure.« less

Structural, elastic, electronic and dynamical properties of OsB and ReB: Density functional calculations

NASA Astrophysics Data System (ADS)

Li, Yanling; Zeng, Zhi; Lin, Haiqing

2010-06-01

The structural, elastic, electronic and dynamical properties of ReB and OsB are investigated by first-principles calculations based on density functional theory. It turns out that ReB and OsB are metallic ultra-incompressible solids with small elastic anisotropy and high hardness. The change of c/ a ratio in OsB indicates that there is a structural phase transition at about 31 GPa. Phonon spectra calculations show that both OsB and ReB are stable dynamically and there are abnormal phonon dispersions along special directions in Brillouin zone. OsB and ReB do not show superconductivity due to very weak electron-phonon interactions in them.

Total cost comparison of 2 biopsy methods for nonpalpable breast lesions.

PubMed

Bodai, B I; Boyd, B; Brown, L; Wadley, H; Zannis, V J; Holzman, M

2001-05-01

To identify, quantify, and compare total facility costs for 2 breast biopsy methods: vacuum-assisted biopsy (VAB) and needle-wire-localized open surgical biopsy (OSB). A time-and-motion study was done to identify unit resources used in both procedures. Costs were imputed from published literature to value resources. A comparison of the total (fixed and variable) costs of the 2 procedures was done. A convenience sample of 2 high-volume breast biopsy (both VAB and OSB) facilities was identified. A third facility (OSB only) and 8 other sites (VAB only) were used to capture variation. Staff interviews, patient medical records, and billing data were used to check observed data. One hundred and sixty-seven uncomplicated procedures (71 OSBs, 96 VABs) were observed. Available demographic and clinical data were analyzed to assess selection bias, and sensitivity analyses were done on the main assumptions. The total facility costs of the VAB procedure were lower than the costs of the OSB procedure. The overall cost advantage for using VAB ranges from $314 to $843 per procedure depending on the facility type. Variable cost comparison indicated little difference between the 2 procedures. The largest fixed cost difference was $763. Facilities must consider the cost of new technology, especially when the new technology is as effective as the present technology. The seemingly high cost of equipment might negatively influence a decision to adopt VAB, but when total facility costs were analyzed, the new technology was less costly.

OsbZIP58, a basic leucine zipper transcription factor, regulates starch biosynthesis in rice endosperm.

PubMed

Wang, Jie-Chen; Xu, Heng; Zhu, Ying; Liu, Qiao-Quan; Cai, Xiu-Ling

2013-08-01

Starch composition and the amount in endosperm, both of which contribute dramatically to seed yield, cooking quality, and taste in cereals, are determined by a series of complex biochemical reactions. However, the mechanism regulating starch biosynthesis in cereal seeds is not well understood. This study showed that OsbZIP58, a bZIP transcription factor, is a key transcriptional regulator controlling starch synthesis in rice endosperm. OsbZIP58 was expressed mainly in endosperm during active starch synthesis. osbzip58 null mutants displayed abnormal seed morphology with altered starch accumulation in the white belly region and decreased amounts of total starch and amylose. Moreover, osbzip58 had a higher proportion of short chains and a lower proportion of intermediate chains of amylopectin. Furthermore, OsbZIP58 was shown to bind directly to the promoters of six starch-synthesizing genes, OsAGPL3, Wx, OsSSIIa, SBE1, OsBEIIb, and ISA2, and to regulate their expression. These findings indicate that OsbZIP58 functions as a key regulator of starch synthesis in rice seeds and provide new insights into seed quality control.

Alloying-Element Loss during High-Temperature Processing of a Nickel-Base Superalloy (Preprint)

DTIC Science & Technology

2013-01-01

precipitates, and the fine white/gray particles are carbides and borides . ............................................. 23 Figure 2. Aluminum...comparable size, and submicron carbides and borides . A fifteen-minute heat treatment at the subsolvus temperature used in the present work (i.e...precipitates, and ~0.3 volume pct. of carbides and borides with an average diameter of ~0.3 m (Figure 1) [5, 6]. B. Procedures To establish the

Amorphous Iron Borides: Preparation, Structure and Magnetic Properties.

DTIC Science & Technology

1982-09-28

temperature. External magnetic field experiments were performed in a superconducting solenoid with both source and absor- ber at 4.2 K. The observed...D-Ai20 919 AMORPHOUS IRON BORIDES: PREPARATION STRUCTURE AND i/i MAGNETIC PROPERTIES(U) JOHNS HOPKINS UNIV LAUREL NO APPLIED PHYSICS LRB K MOORJRNI...NATIONAL BUREAU OF STANOANOS-93-A 10 AMORPHOUS IRON BORIDES: PREPARATION, STRUCTURE ~AND MAGNETIC PROPERTIES FINAL REPORT Kishin Moorjani September 1982 U

Etude des mecanismes de formation des microstructures lors du brasage isotherme de superalliages a base de nickel

NASA Astrophysics Data System (ADS)

Ruiz-Vargas, Jose

This thesis reports theoretical and experimental investigations carried out to understand the mechanisms of microstructure formation during isothermal brazing, produced by brazing Inconel 625 and MC2 nickel-based superalloys with filler metal BNi-2. Firstly, studies were made on pure Ni to interpret microstructure's formation with simplified alloy chemistry. Microstructure formation have been studied when varying time at constant temperature (isothermal kinetics), but also when varying temperature for constant hold time (isochronal kinetics). The chemical composition and crystallography of the present phases have been identified, with the following results : (i) the fraction of dissolved base metal has been found proportional to the initial thickness of the brazing alloy, so that the composition of the liquid remains homogeneous with a precise initial equilibrium composition during the whole brazing process, (ii) the melting of the joint occurs in two steps : at lower temperature, it involves only partially melting, and boron diffusion in pure Ni leads to the precipitation of fine Ni3B borides at the interface ; in a second stage, at higher temperature, melting is complete and thermodynamic equilibrium requires significant dissolution of nickel, which also involves the dissolution of part of borides already formed. Secondly, nickel plating technique was used on Inconel 625 nickel-based superalloy. A thin layer of Ni with varying thickness, has been electrodeposited to observe the gradual dissolution of Inconel and microstructural features formation due to the presence of superalloy alloying elements. It has been observed that the nickel coating does not prevent precipitation in the base metal as boron diffuse rapidly through the coating width. In the intermediate nickel plating width, fragile precipitates of nickel borides have been observed, because the contribution of Inconel alloying elements to the melt was very limited. In absence of nickel plating on the superalloy, the formation of Nb and Cr-Mo borides phase has been observed. Efforts have been made to evaluate the accuracy of Boron measurement by energy dispersion X-ray spectroscopy (EDS) in the MC2 superalloy and BNi-2 filler metal. The most accurate method to quantify Boron using EDS is by composition difference. A precision of 5 at.% has been reached when using optimized data acquisition and post processing schemes. Ultimately, Electron Backscatter Diffraction (EBSD) combined with localized EDS analysis has been proven invaluable in conclusively identifying micrometer sized boride precipitates ; thus further improving the characterization of brazed Ni-based superalloys.

Ex Vivo Maintenance of Primary Human Multiple Myeloma Cells through the Optimization of the Osteoblastic Niche.

PubMed

Zhang, Wenting; Gu, Yexin; Sun, Qiaoling; Siegel, David S; Tolias, Peter; Yang, Zheng; Lee, Woo Y; Zilberberg, Jenny

2015-01-01

We previously reported a new approach for culturing difficult-to-preserve primary patient-derived multiple myeloma cells (MMC) using an osteoblast (OSB)-derived 3D tissue scaffold constructed in a perfused microfluidic environment and a culture medium supplemented with patient plasma. In the current study, we used this biomimetic model to show, for the first time, that the long-term survival of OSB is the most critical factor in maintaining the ex vivo viability and proliferative capacity of MMC. We found that the adhesion and retention of MMC to the tissue scaffold was meditated by osteoblastic N-cadherin, as one of potential mechanisms that regulate MMC-OSB interactions. However, in the presence of MMC and patient plasma, the viability and osteogenic activity of OSB became gradually compromised, and consequently MMC could not remain viable over 3 weeks. We demonstrated that the long-term survival of both OSB and MMC could be enhanced by: (1) optimizing perfusion flow rate and patient-derived plasma composition in the culture medium and (2) replenishing OSB during culture as a practical means of prolonging MMC's viability beyond several weeks. These findings were obtained using a high-throughput well plate-based perfusion device from the perspective of optimizing the ex vivo preservation of patient-derived MM biospecimens for downstream use in biological studies and chemosensitivity analyses.

Ex Vivo Maintenance of Primary Human Multiple Myeloma Cells through the Optimization of the Osteoblastic Niche

PubMed Central

Zhang, Wenting; Gu, Yexin; Sun, Qiaoling; Siegel, David S.; Tolias, Peter; Yang, Zheng

2015-01-01

We previously reported a new approach for culturing difficult-to-preserve primary patient-derived multiple myeloma cells (MMC) using an osteoblast (OSB)-derived 3D tissue scaffold constructed in a perfused microfluidic environment and a culture medium supplemented with patient plasma. In the current study, we used this biomimetic model to show, for the first time, that the long-term survival of OSB is the most critical factor in maintaining the ex vivo viability and proliferative capacity of MMC. We found that the adhesion and retention of MMC to the tissue scaffold was meditated by osteoblastic N-cadherin, as one of potential mechanisms that regulate MMC-OSB interactions. However, in the presence of MMC and patient plasma, the viability and osteogenic activity of OSB became gradually compromised, and consequently MMC could not remain viable over 3 weeks. We demonstrated that the long-term survival of both OSB and MMC could be enhanced by: (1) optimizing perfusion flow rate and patient-derived plasma composition in the culture medium and (2) replenishing OSB during culture as a practical means of prolonging MMC’s viability beyond several weeks. These findings were obtained using a high-throughput well plate-based perfusion device from the perspective of optimizing the ex vivo preservation of patient-derived MM biospecimens for downstream use in biological studies and chemosensitivity analyses. PMID:25973790

Dislocation Decorrelation and Relationship to Deformation Microtwins during Creep of a Gamma’ Precipitate Strengthened Ni-based Superalloy

DTIC Science & Technology

2011-11-01

Deformation is highly localized around stress concentrators such as carbides, borides and serrated grain boundaries, which act as sources of a/2h110i...highly localized around stress concentrators such as carbides, borides and serrated grain boundaries, which act as sources of a/2h110i matrix-type...phase at different thicknesses. 7328 R.R. Unocic et al. / Acta Materialia 59 (2011) 7325–7339 the image. A number of carbide and/or boride phases are

Beta cell device using icosahedral boride compounds

DOEpatents

Aselage, Terrence L.; Emin, David

2002-01-01

A beta cell for converting beta-particle energies into electrical energy having a semiconductor junction that incorporates an icosahedral boride compound selected from B.sub.12 As.sub.2, B.sub.12 P.sub.2, elemental boron having an .alpha.-rhombohedral structure, elemental boron having a .beta.-rhombohedral structure, and boron carbides of the chemical formula B.sub.12-x C.sub.3-x, where 0.15

Finite-size effects and magnetic exchange coupling in thin CoO layers

NASA Astrophysics Data System (ADS)

Ambrose, Thomas Francis

Finite size effects in CoO have been observed in CoO/SiOsb2 multilayers. The Neel temperatures of the CoO layers, as determined by dc susceptibility measurements, follow a finite-size scaling relation with a shift exponent lambda = 1.55 ± 0.05. This determined exponent is close to the theoretical value for finite size scaling in an Ising system. The value of the zero temperature correlation length has also been determined to be 18A, while antiferromagnetic ordering persists down to a CoO layer thickness of 10A. The properties of exchange biasing have been extensively studied in NiFe/CoO bilayers. The effects of the cooling field (Hsb{FC}), up to 50 kOe, on the resultant exchange field (Hsb{E}) and coercivity (Hsb{C}) have been examined. The value of Hsb{E} increases rapidly at low cooling fields (Hsb{FC} < 1kOe) and levels off for Hsb{FC} larger than 4 kOe. The value of Hsb{C} also depends upon Hsb{FC}, but less sensitively. The bilayer thickness also influences exchange biasing. We find that Hsb{E} varies inversely proprotional to both tsb{FM} and tsb{AF} where tsb{FM} and tsb{AF} are the ferromagnetic and antiferromagnetic layer thickness respectively. Because of the 1/tsb{AF}, the simple picture of interfacial coupling between ferromagnet and antiferromagnet spins appears to be inadequate. The assertion of long range coupling between ferromagnetic and antiferromagnetic layers has been verified by the observation of antiferromagnetic exchange coupling across spacer layers in NiFe/NM/CoO trilayers, where NM is a non-magnetic material. Exchange biasing has been observed in trilayers with metallic spacer layers up to 50A thick using Ag, Cu and Au, while no exchange field was observed for insulating spacer layers of any thickness using Alsb2Osb3, SiOsb2 and MgO. The temperature dependence of Hsb{E} and Hsb{C} and the effect of the deposition order have been studied in a series of bilayer (NiFe/CoO and CoO/NiFe) and trilayer (NiFe/CoO/NiFe) films. A profound difference in Hsb{E} was observed in samples with NiFe deposited on top of CoO compared to samples with CoO deposited on top of NiFe. When CoO is on top of NiFe Hsb{E} varies linearly with temperature, while for samples with NiFe on top of CoO Hsb{E} has a plateau followed by a rapid decrease. These distinct temperature dependences have been reproduced in NiFe/CoO/NiFe trilayers which contain both geometries. Structural analysis using Transmission Electron Microscopy indicate no apparent differences in the top and bottom interfaces. The angular dependence of the exchange coupling in a NiFe/CoO bilayer has been measured. Both Hsb{E} and Hsb{C} with unidirectional and uniaxial characteristics, respectively, are integral parts of the exchange coupling. The values of Hsb{E} can be expressed by a series of odd angle cosine terms, while the values of Hsb{C} can be expressed by a series of even angle cosine terms. Finally, exchange biasing has been used to "spin engineer" ferromagnetic layers in NiFe/CoO/NiFe trilayers. Four different spin structures have been observed. A phase diagram, for the four spin structures and the conditions with which each spin structure is obtained, has been determined. (Abstract shortened by UMI.)

Ship Dynamics in the Surf Zone Model Testing

DTIC Science & Technology

2008-07-01

was implemented for ease of transportation and ease of assembly. Each module was 10 feet square consisting of oriented strand board ( OSB ) plywood with...frame, constructed of 2 inch by 4 inch by 10 feet pieces of wood, was measured, cut, laid, and screwed together for each module. Pieces of OSB

Electronic Structure Properties and a Bonding Model of Thermoelectric Half-Heusler and Boride Phases

NASA Astrophysics Data System (ADS)

Simonson, Jack William

Half-Heusler alloys MNiSn and MCoSb (M = Ti, Zr, Hf) and layered boride intermetallics with structure types YCrB4 and Er 3CrB7 were designed, synthesized, and characterized. The thermoelectric properties of these two classes of alloys were measured from room temperature to 1100 K with the intent of indirectly studying their electronic structure properties and gauging not only their suitability but that of related alloys for high temperature thermoelectric power generation. In the case of the half-Heusler alloys, transition metals were substituted to both the M and Ni/Co sites to study the resultant modifications of the d-orbital-rich portion of the electronic structure near the Fermi energy. This modification and subsequent pinning of the Fermi energy within the gap is discussed herein in terms of first principles electronic structure calculations from the literature. In the half-Heusler alloys, it was found that substitution of transition metals invariably led to a decrease in the thermopower, while the resistivity typically maintained its semiconducting trend. On the other hand, Sn doping in MCoSb type alloys -- a dopant that has been known for some time to be efficient -- was shown to result in high ZT at temperatures in excess of 1000 K. Moreover, the band gaps of the transition metal-doped alloys measured in this work offer insight into the discrepancy between the predicted and measured band gaps in the undoped parent compositions. In the case of the layered boride alloys, on the other hand, few electronic calculations have been published, thus prompting the generalization of a well-known electron counting rule -- which is typically used to study molecular organometallics, boranes, and metallocenes -- to predict the trends in the densities of states of crystalline solids that possess the requisite deltahedral bonding geometry. In accordance with these generalized electronic counting rules, alloys of the form RMB4 (R = Y, Gd, Ho; M = Cr, Mo, W) were measured to be n-type semiconductors with band gaps ranging from 0.15 eV to 0.25 eV. These alloys exhibited thermoelectric power factors comparable with those of other potential boride thermoelectric materials reported in the literature. Furthermore, as a result of the procedure developed for precision synthesis of boron-rich intermetallics and the improved understanding of bonding trends, layered borides of several previously overlooked structure-types were synthesized and screened for superconductivity. Consequently, alloys of the MoB4 phase were discovered to be superconducting when doped with Nb or Ti. Electrical resistivity measurements of superconducting transitions between 6 and 8 K in these materials were confirmed via magnetic susceptibility measurements and x-ray diffraction. Structural measurements indicated opposite trends in lattice modification than those reported for the superconducting transition metal diborides.

The cost-effectiveness of fine-needle aspiration cytology and 14-gauge core needle biopsy compared with open surgical biopsy in the diagnosis of breast carcinoma.

PubMed

Logan-Young, W; Dawson, A E; Wilbur, D C; Avila, E E; Tomkiewicz, Z M; Sheils, L A; Laczin, J A; Taylor, A S

1998-05-15

Judicious utilization of fine-needle aspiration cytology (FNAC) and 14-gauge core needle biopsy (CB) theoretically should result in greater accuracy in breast carcinoma diagnosis and fewer unnecessary open surgical biopsies (OSBs), thus lowering health care costs. In 1995 in Rochester, New York, the ratio of open surgical breast biopsies per each verified breast carcinoma (OSB/Ca) in a freestanding breast clinic (EWBC) was compared with the OSB/Ca ratio of all physicians in the remainder of the city. The EWBC differs from all other diagnostic facilities in Rochester in that it routinely performs FNAC and CB. The EWBC recommended 462 OSBs resulting in 310 verified carcinomas, for a OSB/Ca ratio of 1.5. The physicians in the remainder of the city recommended 2036 OSBs resulting in 513 verified carcinomas, for a OSB/Ca ratio of 4.0. If the EWBC OSB/Ca ratio had been identical to the remainder of the city, the number of extra OSBs recommended by the clinic would have been 778, resulting in an additional cost of $1,712,082. When the added cost of the 2594 FNACs ($256,285) and 403 CBs ($252,278) performed by the clinic was subtracted from the $1,712,082, the freestanding breast clinic cost savings was $1,203,519. The lymph node metastasis rate of 19% for the breast carcinomas diagnosed in clinic patients was identical to that of the women with breast carcinoma in the remainder of the city. Utilization of FNAC and CB allows radiologists to lower their OSB/Ca ratio without sacrificing early detection. In this study, these less expensive procedures result in lowered medical costs for the health care system.

Nqrs Data for C6H7F7N2OSb2 (Subst. No. 0880)

NASA Astrophysics Data System (ADS)

Chihara, H.; Nakamura, N.

This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H7F7N2OSb2 (Subst. No. 0880)

Utilization of waste tire rubber in manufacture of oriented strandboard.

PubMed

Ayrilmis, Nadir; Buyuksari, Umit; Avci, Erkan

2009-09-01

Some physical and mechanical properties of oriented strandboards (OSBs) containing waste tire rubber at various addition levels based on the oven-dry strand weight, using the same method as that used in the manufacture of OSB. Two resin types, phenol-formaldehyde (PF) and polyisocyanate, were used in the experiments. The manufacturing parameters were: a specific gravity of 0.65 and waste tire rubber content (10/90, 20/80 and 30/70 by wt.% of waste tire rubber/wood strand). Average internal bond values of PF-bonded OSB panels with rubber chips were between 17.6% and 48.5% lower than the average of the control samples while polyisocyanate bonded OSBs were 16.5-50.6%. However, water resistance and mechanical properties of OSBs made using polyisocyanate resin were found to comply with general-purpose OSB minimum property requirements of EN 300 Type 1 (1997) values for use in dry conditions at the lowest tire rubber loading level (10%) based on the oven-dry panel weight. The tire rubber improved water resistance of the OSB panel due to its almost hydrophobic property. Based on the findings obtained from this study, we concluded that waste tire rubber could be used for general-purpose OSB manufacturing up to 10% ratio based on the oven-dry panel weight.

Plasma boriding of a cobalt-chromium alloy as an interlayer for nanostructured diamond growth

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.; Jubinsky, Matthew; Catledge, Shane A.

2015-02-01

Chemical vapor deposited (CVD) diamond coatings can potentially improve the wear resistance of cobalt-chromium medical implant surfaces, but the high cobalt content in these alloys acts as a catalyst to form graphitic carbon. Boriding by high temperature liquid baths and powder packing has been shown to improve CVD diamond compatibility with cobalt alloys. We use the microwave plasma-enhanced (PE) CVD process to deposit interlayers composed primarily of the borides of cobalt and chromium. The use of diborane (B2H6) in the plasma feedgas allows for the formation of a robust boride interlayer for suppressing graphitic carbon during subsequent CVD of nano-structured diamond (NSD). This metal-boride interlayer is shown to be an effective diffusion barrier against elemental cobalt for improving nucleation and adhesion of NSD coatings on a CoCrMo alloy. Migration of elemental cobalt to the surface of the interlayer is significantly reduced and undetectable on the surface of the subsequently-grown NSD coating. The effects of PECVD boriding are compared for a range of substrate temperatures and deposition times and are evaluated using glancing-angle X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Raman spectroscopy. Boriding of CoCrMo results in adhered nanostructured diamond coatings with low surface roughness.

Search for New Superconductors for Energy and Power Applications

DTIC Science & Technology

2014-10-21

superconductors, borides , carbides, silicides, and chalcogenides. In addition, a number of thin film systems have been explored: A15s, superlattices, arrays of...YBa2Cu3O7 Bi2Se3 Eu-Si-C ErRh4B4 Bi2Sr2CaCu2O8 (UD, OD) Sb2Se3 V-Si-C (Ga,Mn)As CuO ZrSe2 Sm-Si-C Hf(FeCo)P Y1-xCaxCrO3 Fe-Te-Se BORIDES Hf-Fe-C-P...Physics, Warsaw, Poland Table III New superconductors, discovered by UCSD MURI team. BORIDES Tc (K) Nb0.9Zr0.1B 11.2 ZrNbxB 9.0 ZrVxB 9.0

Metal Immiscibility Route to Synthesis of Ultrathin Carbides, Borides, and Nitrides.

PubMed

Wang, Zixing; Kochat, Vidya; Pandey, Prafull; Kashyap, Sanjay; Chattopadhyay, Soham; Samanta, Atanu; Sarkar, Suman; Manimunda, Praveena; Zhang, Xiang; Asif, Syed; Singh, Abhisek K; Chattopadhyay, Kamanio; Tiwary, Chandra Sekhar; Ajayan, Pulickel M

2017-08-01

Ultrathin ceramic coatings are of high interest as protective coatings from aviation to biomedical applications. Here, a generic approach of making scalable ultrathin transition metal-carbide/boride/nitride using immiscibility of two metals is demonstrated. Ultrathin tantalum carbide, nitride, and boride are grown using chemical vapor deposition by heating a tantalum-copper bilayer with corresponding precursor (C 2 H 2 , B powder, and NH 3 ). The ultrathin crystals are found on the copper surface (opposite of the metal-metal junction). A detailed microscopy analysis followed by density functional theory based calculation demonstrates the migration mechanism, where Ta atoms prefer to stay in clusters in the Cu matrix. These ultrathin materials have good interface attachment with Cu, improving the scratch resistance and oxidation resistance of Cu. This metal-metal immiscibility system can be extended to other metals to synthesize metal carbide, boride, and nitride coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nqrs Data for C6H7F4N2OSb (Subst. No. 0879)

NASA Astrophysics Data System (ADS)

Chihara, H.; Nakamura, N.

This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H7F4N2OSb (Subst. No. 0879)

Comparison of histologic diagnosis between stereotactic core needle biopsy and open surgical biopsy.

PubMed

Bauer, R L; Sung, J; Eckhert, K H; Koul, A; Castillo, N B; Nemoto, T

1997-06-01

This study correlates the histologic findings of stereotactic core needle biopsy (SCNB) with open surgical biopsy (OSB) and identifies which lesions can be treated definitively based only on the SCNB histology. Women who underwent SCNB between July 1, 1993, and January 1, 1969, were identified by retrospective chart review. Mammographic (MGM) lesions found by SCNB to be ductal or lobular hyperplasia with atypia, or carcinoma underwent OSB. When the histologic findings by SCNB were inconsistent with the MGM findings, the lesion also underwent OSB. 799 women underwent SCNB with 96 (12%) of these going on to OSB. MGM findings in the 92 who presented without a palpable mass included microcalcifications (MCS) in 39, mass in 47, MCS and mass in 7, and tissue distortion in 3. One hundred one breast lesions biopsied first by SCNB, then by OSB were correlated histologically. Sensitivity of SCNB is 89%, with a specificity of 94%. Eight-four women (88%) were able to have definitive treatment at time of OSB because of prior SCNB, and 703/799 (88%) of women were spared OSB entirely. SCNB accurately identifies benign breast histology and invasive cancers in women with MGM abnormalities, a distinct advantage over fine needle aspiration cytology. SCNB does not reliably identify women with DCIS and invasion. All women with SCNB diagnosis of ductal or lobular atypia should also undergo OSB.

Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

PubMed

Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

2016-08-31

The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

Acoustic Doppler Current Profiler (ADCP) Velocity Verification Experiments in the Navy’s Large Cavitation Channel (LCC)

DTIC Science & Technology

2007-12-01

79 ~~~~ ~_ 6/3 .Irhs et1 4 oSB 3. 0 0 413 ll c1501- 80 6_ 1 20 _ _ _ dcane Wok1_c $tro 5052_00 vc]35_0713-2- _ _j 45 to_ _ STBD 0_ 34.8 I0 3 81 6...0I48 70 3 500005 nn 844 6/13 20 dezwonWtakhorae Seninl 45 toSTBD 0 20. 005 30 4k3O0505 neI201 88 ~~~1 U13 d= Sunl 4 oSB 23 70 2 %22000 W201 2Q tl...700 3 4= /27 vc]3-07143 W5 6/4a 45 oSB /0d 2.8 0 0 45 m O w1 3-0714- 164 61/4 204,, W4/5,,tO, tSo STUD lOdown, 39.0 700 30 45000mI,15 3 /-0714.3 /659

Superplastic behavior of two ultrahigh boron steels

NASA Astrophysics Data System (ADS)

Jiménez, J. A.; González-Doncel, G.; Acosta, P.; Ruano, O. A.

1994-06-01

The high-temperature deformation behavior of two ultrahigh boron steels containing 2.2 pct and 4.9 pct B was investigated. Both alloys were processed via powder metallurgy involving gas atomization and hot isostatic pressing (hipping) at various temperatures. After hipping at 700 °C, the Fe-2.2 pct B alloy showed a fine microstructure consisting of l- µm grains and small elongated borides (less than 1 µm) . At 1100 °C, a coarser microstructure with rounded borides was formed. This alloy was superplastic at 850 °C with stress exponents of about two and tensile elongations as high as 435 pct. The microstructure of the Fe-4.9 pct B alloy was similar to that of the Fe-2.2 pct B alloy showing, in addition, coarse borides. This alloy also showed low stress exponent values but lacked high tensile elongation (less than 65 pct), which was attributed to the presence of stress accumulation at the interface between the matrix and the large borides. A change in the activation energy value at the α-γ transformation temperature was seen in the Fe-2.2 pct B alloy. The plastic flow data were in agreement with grain boundary sliding and slip creep models.

Theoretical and Experimental Investigations on the Mechanism of Carbothermal Reduction of Zirconia (Preprint)

DTIC Science & Technology

2012-08-01

Properties. Abyss Books, Washington, D.C., 2002. 2. G. Montel, A. Lebugle and H. Pastor. "Manufacture of Materials Containing Refractory Borides ...and ZrO2," International Journal of Refractory Metals and Hard Materials, 17, 235-43 (1999). 10. A.W. Weimer, Carbide, nitride and boride

An Evolutionary History of Oriented Strandboard (OSB)

Treesearch

John I. Zerbe; Zhiyong Cai; George B. Harpole

2015-01-01

To improve wood utilization efficiency, oriented strandboard (OSB) was developed; 80% of the wood removed from the forest can now be processed into marketable products. This manuscript describes the history of developing this most profitable wood product, OSB, and the early FPL contribution in development.

High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics

NASA Astrophysics Data System (ADS)

Gild, Joshua; Zhang, Yuanyao; Harrington, Tyler; Jiang, Sicong; Hu, Tao; Quinn, Matthew C.; Mellor, William M.; Zhou, Naixie; Vecchio, Kenneth; Luo, Jian

2016-11-01

Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides. Greater than 92% of the theoretical densities have been generally achieved with largely uniform compositions from nanoscale to microscale. Aberration-corrected scanning transmission electron microscopy (AC STEM), with high-angle annular dark-field and annular bright-field (HAADF and ABF) imaging and nanoscale compositional mapping, has been conducted to confirm the formation of 2-D high-entropy metal layers, separated by rigid 2-D boron nets, without any detectable layered segregation along the c-axis. These materials represent a new type of ultra-high temperature ceramics (UHTCs) as well as a new class of high-entropy materials, which not only exemplify the first high-entropy non-oxide ceramics (borides) fabricated but also possess a unique non-cubic (hexagonal) and layered (quasi-2D) high-entropy crystal structure that markedly differs from all those reported in prior studies. Initial property assessments show that both the hardness and the oxidation resistance of these high-entropy metal diborides are generally higher/better than the average performances of five individual metal diborides made by identical fabrication processing.

Yttria Nanoparticle Reinforced Commercially Pure (CP) Titanium

DTIC Science & Technology

2011-09-01

nanoparticles as well as titanium boride (TiB) reinforcements were produced through gas atomization. After consolidation and extrusion, room temperature...pure FE iron O oxygen Ti titanium TiB titanium boride TYS tensile yield strength UTS ultimate tensile strength wt% weight percent Y2O3

Surface decoration through electrostatic interaction leading to enhanced reactivity: Low temperature synthesis of nanostructured chromium borides (CrB and CrB{sub 2})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menaka,; Kumar, Bharat; Kumar, Sandeep

The present study describes a novel low temperature route at ambient pressure for the synthesis of nanocrystalline chromium borides (CrB and CrB{sub 2}) without using any flux or additives. The favorable and intimate mixing of nanoparticles of chromium acetate (Cr source) and boron forms an active chromium–boron precursor which decomposes at much lower temperature (400 °C) to form CrB (which is ∼1000 °C less than the known ambient pressure synthesis). The chromium acetate nanoparticles (∼5 nm) decorate the larger boron particles (150–200 nm) due to electrostatic interactions resulting from opposing surface charges of boron (zeta potential:+48.101 mV) and chromium acetatemore » (zeta potential:−4.021 mV) in ethanolic medium and is evident in the TEM micrographs. The above method leads to the formation of pure CrB film like structure at 400 °C and nanospheres (40–60 nm) at 600 °C. Also, chromium diboride (CrB{sub 2}) nanoparticles (25 nm) could be obtained at 1000 °C. - Graphical abstract: Variation of surface charge of reactants, precursor and the products, chromium borides (CrB and CrB{sub 2}). Highlights: ► Novel borothermal reduction process for synthesis of chromium boride. ► Significant lowering of reaction temperature to obtain nanocrystalline chromium boride. ► Enhanced reactivity due to appropriate surface interactions.« less

Biosynthesis of o-succinylbenzoic acid in Bacillus subtilis: identification of menD mutants and evidence against the involvement of the alpha-ketoglutarate dehydrogenase complex.

PubMed Central

Palaniappan, C; Taber, H; Meganathan, R

1994-01-01

The biosynthesis of o-succinylbenzoic acid (OSB), the first aromatic intermediate involved in the biosynthesis of menaquinone (vitamin K2) is demonstrated for the first time in the gram-positive bacterium Bacillus subtilis. Cell extracts were found to contain isochorismate synthase, 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylic acid (SHCHC) synthase-alpha-ketoglutarate decarboxylase and o-succinylbenzoic acid synthase activities. An odhA mutant which lacks the decarboxylase component (usually termed E1, EC 1.2.4.2, oxoglutarate dehydrogenase [lipoamide]) of the alpha-ketoglutarate dehydrogenase complex was found to synthesize SHCHC and form succinic semialdehyde-thiamine pyrophosphate. Thus, the presence of an alternate alpha-ketoglutarate decarboxylase activity specifically involved in menaquinone biosynthesis is established for B. subtilis. A number of OSB-requiring mutants were also assayed for the presence of the various enzymes involved in the biosynthesis of OSB. All mutants were found to lack only the SHCHC synthase activity. PMID:8169214

Cation coordination in oxychloride glasses

NASA Astrophysics Data System (ADS)

Johnson, J. A.; Holland, D.; Bland, J.; Johnson, C. E.; Thomas, M. F.

2003-02-01

Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2].

Computational study of Zn-doped quantum spin chains and ladders

NASA Astrophysics Data System (ADS)

Laukamp, Markus

In this dissertation, the powerful Density Matrix Renormalization Group method is applied to examine the properties of spin models. The method allows to determine accurately the properties of low lying states of finite systems of large sizes. The results gained with this technique are compared to results generated with exact diagonalization and Monte Carlo techniques. Spin models have been proposed to describe dimerized chains, ladders, two dimensional antiferromagnets, and other compounds. Here the focus is on the case where some spins are replaced by spinless vacancies. This happens e.g. upon Zn doping, when Cusp{2+} atoms are replaced by Znsp{2+}. A small percentage of vacancies rapidly destroys the spin gap, and their presence induces enhanced antiferromagnetic correlations near those vacancies. Since the phenomenon of enhanced antiferromagnetism is found to occur in several models and cluster geometries, a common simple explanation for its presence may exist. In this thesis it is argued that the resonating-valence-bond character of the spin correlations at short distances of a large variety of models is responsible for the presence of robust staggered spin correlations near vacancies and lattice edges. The phenomenon takes place regardless of the long distance properties of the ground state, and it is caused by a "pruning" of the available spin singlets in the vicinity of the vacancies. The effect produces a broadening of the low temperature NMR signal for the compounds analyzed here. This broadening should be experimentally observable in the structurally dimerized chain systems Cu(NOsb3)sb{*}2.5Hsb2O,\\ CuWOsb4,\\ (VO)sb2Psb2Osb7, and Srsb{14}Cusb{24}Osb{41}, in ladder materials such as SrCusb2Osb3, in the spin-Peierls systems CuGeOsb3 and NaVsb2Osb5, and in several others since it is a universal effect common to a wide variety of models and compounds. In addition, it is argued that the Neel order observed in SrCusb2Osb3 upon Zn doping is induced by the local antiferromagnetic order discussed in this paper, enhanced by a favorable ratio between the actual Heisenberg couplings along chains and rungs, as reported in recent experimental literature. Based on this reasoning it is here predicted that other ladder materials such as Zn-doped Cusb2(Csb5Hsb{12}Nsb2)sb2Clsb4 will not present Neel order at small Zn concentrations.

Mechanism of MenE Inhibition by Acyl-Adenylate Analogues and Discovery of Novel Antibacterial Agents

PubMed Central

Sharma, Indrajeet; Lavaud, Lubens J.; Ngo, Stephen C.; Shek, Roger; Rajashankar, Kanagalaghatta R.; French, Jarrod B.; Tan, Derek S.; Tonge, Peter J.

2015-01-01

MenE is an o-succinylbenzoyl-CoA (OSB-CoA) synthetase in the bacterial menaquinone biosynthesis pathway and is a promising target for the development of novel antibacterial agents. The enzyme catalyzes CoA ligation via an acyl-adenylate intermediate, and we have previously reported tight-binding inhibitors of MenE based on stable acyl-sulfonyladenosine analogues of this intermediate, including OSB-AMS (1) which has an IC50 value of ≤ 25 nM for the Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in S. aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is ~1000-fold lower than the IC50 for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure–activity relationship (SAR) study stimulated by the knowledge that OSB-AMS can adopt two isomeric forms in which the OSB side chain exists either as an open-chain keto acid or a cyclic lactol. These studies revealed that negatively charged analogues of the keto-acid form bind, while neutral analogues do not, consistent with the hypothesis that the negatively-charged keto-acid form of OSB-AMS is the active isomer. X-ray crystallography and site-directed mutagenesis confirm the importance of a conserved arginine for binding the OSB carboxylate. Although most lactol isomers tested were inactive, a novel difluoroindanediol inhibitor (11) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future. PMID:26394156

Mechanism of MenE inhibition by acyl-adenylate analogues and discovery of novel antibacterial agents.

PubMed

Matarlo, Joe S; Evans, Christopher E; Sharma, Indrajeet; Lavaud, Lubens J; Ngo, Stephen C; Shek, Roger; Rajashankar, Kanagalaghatta R; French, Jarrod B; Tan, Derek S; Tonge, Peter J

2015-10-27

MenE is an o-succinylbenzoyl-CoA (OSB-CoA) synthetase in the bacterial menaquinone biosynthesis pathway and is a promising target for the development of novel antibacterial agents. The enzyme catalyzes CoA ligation via an acyl-adenylate intermediate, and we have previously reported tight-binding inhibitors of MenE based on stable acyl-sulfonyladenosine analogues of this intermediate, including OSB-AMS (1), which has an IC50 value of ≤25 nM for Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in Staphylococcus aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is ∼1000-fold lower than the IC50 for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure-activity relationship (SAR) study stimulated by the knowledge that OSB-AMS can adopt two isomeric forms in which the OSB side chain exists either as an open-chain keto acid or a cyclic lactol. These studies revealed that negatively charged analogues of the keto acid form bind, while neutral analogues do not, consistent with the hypothesis that the negatively charged keto acid form of OSB-AMS is the active isomer. X-ray crystallography and site-directed mutagenesis confirm the importance of a conserved arginine for binding the OSB carboxylate. Although most lactol isomers tested were inactive, a novel difluoroindanediol inhibitor (11) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future.

Directionally Solidified Eutectic Ceramics for Multifunctional Aerospace Applications

DTIC Science & Technology

2013-01-01

eutectic materials development through a new initiative entitled Boride Eutectic Project. These results first time organize and populate materials...property databases, and utilize an iterative feedback routine to constantly improve the design process of the boride eutectics LaB6-MeB2 (Me = Zr, Hf, Ti

First-principles study of elastic and thermodynamic properties of orthorhombic OsB4 under high pressure

NASA Astrophysics Data System (ADS)

Yan, Hai-Yan; Zhang, Mei-Guang; Huang, Duo-Hui; Wei, Qun

2013-04-01

The first-principles study on the elastic properties, elastic anisotropy and thermodynamic properties of the orthorhombic OsB4 is reported using density functional theory method with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation. The calculated equilibrium parameters are in good agreement with the available theoretical data. A complete elastic tensor and crystal anisotropies of the ultra-incompressible OsB4 are determined in the pressure range of 0-50 GPa. By the elastic stability criteria, it is predicted that the orthorhombic OsB4 is stable below 50 GPa. By using the quasi-harmonic Debye model, the heat capacity, the coefficient of thermal expansion, and the Grüneisen parameter of OsB4 are also successfully obtained in the present work.

OsB 2 and RuB 2, ultra-incompressible, hard materials: First-principles electronic structure calculations

NASA Astrophysics Data System (ADS)

Chiodo, S.; Gotsis, H. J.; Russo, N.; Sicilia, E.

2006-07-01

Recently it has been reported that osmium diboride has an unusually large bulk modulus combined with high hardness, and consequently is a most interesting candidate as an ultra-incompressible and hard material. The electronic and structural properties of the transition metal diborides OsB 2 and RuB 2 have been calculated within the local density approximation (LDA). It is shown that the high hardness is the result of covalent bonding between transition metal d states and boron p states in the orthorhombic structure.

Demonstration of Shear Localization in Ultrafine Grained Tungsten Alloys via Powder Metallurgy Processing Route

DTIC Science & Technology

2012-09-01

of a di-tungsten boride (W2B) phase was not detected in the nW-B sample, but the low concentration of boron may have made this phase undetectable by...Split Hopkinson Bar UFG ultrafine grained W2B di-tungsten boride XRD x-ray diffraction NO. OF NO. OF COPIES ORGANIZATION COPIES

Endothelial-to-Osteoblast Conversion Generates Osteoblastic Metastasis of Prostate Cancer.

PubMed

Lin, Song-Chang; Lee, Yu-Chen; Yu, Guoyu; Cheng, Chien-Jui; Zhou, Xin; Chu, Khoi; Murshed, Monzur; Le, Nhat-Tu; Baseler, Laura; Abe, Jun-Ichi; Fujiwara, Keigi; deCrombrugghe, Benoit; Logothetis, Christopher J; Gallick, Gary E; Yu-Lee, Li-Yuan; Maity, Sankar N; Lin, Sue-Hwa

2017-06-05

Prostate cancer (PCa) bone metastasis is frequently associated with bone-forming lesions, but the source of the osteoblastic lesions remains unclear. We show that the tumor-induced bone derives partly from tumor-associated endothelial cells that have undergone endothelial-to-osteoblast (EC-to-OSB) conversion. The tumor-associated osteoblasts in PCa bone metastasis specimens and patient-derived xenografts (PDXs) were found to co-express endothelial marker Tie-2. BMP4, identified in PDX-conditioned medium, promoted EC-to-OSB conversion of 2H11 endothelial cells. BMP4 overexpression in non-osteogenic C4-2b PCa cells led to ectopic bone formation under subcutaneous implantation. Tumor-induced bone was reduced in trigenic mice (Tie2 cre /Osx f/f /SCID) with endothelial-specific deletion of osteoblast cell-fate determinant OSX compared with bigenic mice (Osx f/f /SCID). Thus, tumor-induced EC-to-OSB conversion is one mechanism that leads to osteoblastic bone metastasis of PCa. Copyright © 2017 Elsevier Inc. All rights reserved.

Passivating overcoat bilayer for multilayer reflective coatings for extreme ultraviolet lithography

DOEpatents

Montcalm, Claude; Stearns, Daniel G.; Vernon, Stephen P.

1999-01-01

A passivating overcoat bilayer is used for multilayer reflective coatings for extreme ultraviolet (EUV) or soft x-ray applications to prevent oxidation and corrosion of the multilayer coating, thereby improving the EUV optical performance. The overcoat bilayer comprises a layer of silicon or beryllium underneath at least one top layer of an elemental or a compound material that resists oxidation and corrosion. Materials for the top layer include carbon, palladium, carbides, borides, nitrides, and oxides. The thicknesses of the two layers that make up the overcoat bilayer are optimized to produce the highest reflectance at the wavelength range of operation. Protective overcoat systems comprising three or more layers are also possible.

Understanding properties of commercial OSB products

Treesearch

Siqun Wang; Hongmei Gu; Trairat Neimsuwan

2004-01-01

Oriented strandboard (OSB) has gained increased market acceptance as a construction material in almost all geographical areas of Canada and United States. With its growing market, more and more research has been focused on the product’s manufacturing and performance. Commercial OSB products in U.S. and Canada are produced from different manufacturers with different...

The Nature of the Microstructure and Interface Boundary Formation in Directionally Solidified Ceramic Boride Composites

DTIC Science & Technology

2015-02-19

boride composites *Volodymyr Borysovych Filipov SCIENCE AND TECHNOLOGY CENTER IN UKRAINE METALISTIV 7A, KYIV, UKRAINE *FRANTSEVICH...microstructure and interface boundary formation in directionally solidified ceramic boride composites 5a. CONTRACT NUMBER STCU P-512 5b. GRANT NUMBER...BOUNDARY FORMATION IN DIRECTIONALLY SOLIDIFIED CERAMIC BORIDE COMPOSITES Project manager: Filipov Volodymyr Borysovych Phone: (+380.44) 424-13-67

Radio Frequency Scanning and Simulation of Oriented Strand Board Material Property

NASA Astrophysics Data System (ADS)

Liu, Xiaojian; Zhang, Jilei; Steele, Philip. H.; Donohoe, J. Patrick

2008-02-01

Oriented strandboard (OSB) is a wood composite product with the largest market share in U.S. residential and commercial construction. Wood specific gravity (SG) and moisture content (MC) play an important role in the OSB manufacturing process. They are the two of the critical variables that manufacturers are required to monitor, locate, and control in order to produce a product with consistent quality. In this study, radio frequency scanning nondestructive evaluation (NDE) technologies evaluated the local area MC and SG of OSB panels following panel production by hot pressing. A finite element software simulation tool was used to optimize the sensor geometry and for investigating the interaction between electromagnetic field and wood dielectric properties. Our results indicate the RF scanning response is closely correlated to the MC and SG variations in OSB panels. Radio frequency NDE appears to have potential as an effective method for insuring OSB panel quality during manufacturing.

Effects of Tungsten Addition on the Microstructure and Corrosion Resistance of Fe-3.5B Alloy in Liquid Zinc

PubMed Central

Liu, Xin; Wang, Mengmeng; Yin, Fucheng; Ouyang, Xuemei; Li, Zhi

2017-01-01

The effects of tungsten addition on the microstructure and corrosion resistance of Fe-3.5B alloys in a liquid zinc bath at 520 °C were investigated by means of scanning electron microscopy, X-ray diffraction and electron probe micro-analysis. The microstructure evolution in different alloys is analyzed and discussed using an extrapolated Fe-B-W ternary phase diagram. Experimental results show that there are three kinds of borides, the reticular (Fe, W)2B, the rod-like (Fe, W)3B and flower-like FeWB. The addition of tungsten can refine the microstructure and improve the stability of the reticular borides. Besides, it is beneficial to the formation of the metastable (Fe, W)3B phase. The resultant Fe-3.5B-11W (wt %) alloy possesses excellent corrosion resistance to liquid zinc. When tungsten content exceeds 11 wt %, the formed flower-like FeWB phase destroys the integrity of the reticular borides and results in the deterioration of the corrosion resistance. Also, the corrosion failure resulting from the spalling of borides due to the initiation of micro-cracks in the grain boundary of borides is discussed in this paper. PMID:28772759

NQRS Data for C7H8Cl3Osb (Subst. No. 1005)

NASA Astrophysics Data System (ADS)

Chihara, H.; Nakamura, N.

This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C7H8Cl3OSb (Subst. No. 1005)

Characterization of ceria electrolyte in solid oxide fuel cell applications

NASA Astrophysics Data System (ADS)

Milliken, Christopher Edward

The goal of this research effort is to characterize cation doped cerium dioxide for use as an electrolyte material in solid oxide fuel cell applications. A variety of analytical techniques including thermogravimetric analysis, controlled atmosphere dilatometry, and AC/DC electronic measurements on single cells and stacks have been coupled with thermodynamic calculations to evaluate the suitability of several doping schemes. The results of this analysis indicate that doping CeOsb2 with 20% SmOsb{1.5} or codoping with 19% GdOsb{1.5} + 1% PrOsb{1.83} provides the best combination of stability and performance. Under dual atmosphere fuel cell conditions, these dopants do not provide sufficient stabilization energy to prevent the reduction of ceria. A significant oxygen leakage current can be expected, particularly near open circuit conditions. Incorporation of 10% SrO provides similar short-term advantages to the lanthanide doped system but this electrolyte material undergoes an irreversible degradation mechanism that results in cell failure within 1500 hours of test. Under fuel cell conditions, the maximum efficiency of such systems in stacks will be below 40% at 200 mW/cmsp2 when operated on humidified hydrogen fuels. This compares to an expected efficiency of 45-50% at a similar power density for nonmixed conducting electrolyte (e.g., YSZ).

Taguchi Analysis on the Effect of Process Parameters on Densification During Spark Plasma Sintering of HfB2-20SiC (Preprint)

DTIC Science & Technology

2011-11-01

30 kN pressure and heating rate of 100 K/min. Introduction Boride , carbides and nitrides of the group IVB and VB transition metals are considered...10. Sciti D., Silvestroni L., Nygren M. Spark plasma sintering of Zr- and Hf- borides with decreasing amounts of MoSi2 as sintering aid Journal of

Phase identification in boron-containing powder metallurgy steel using EBSD in combination with EPMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ming-Wei, E-mail: mwwu@ntut.edu.tw; Cai, Wen-Zhang

2016-03-15

Boron (B) is extensively used to induce liquid phase sintering (LPS) in powder metallurgy (PM) steels and thereby increase the densification. The alloying elements in B-containing PM steels affect the boride phase, stability of the boride, the temperature of liquid formation, and the progress of LPS. However, the boride phase has not been systematically identified yet. The main objective of this study was to clarify the influences of alloying elements, including C, Cr, and Ni, on the boride phases using electron backscatter diffraction (EBSD) in combination with electron probe microanalysis (EPMA). Network structures consisting of ferrite, Fe{sub 2}B boride, andmore » Fe{sub 3}C carbide were extensively observed in the Fe–0.4B–0.5C steel. The portions of Fe{sub 2}B were sufficiently larger than those of Fe{sub 3}C, and Fe{sub 3}C was mostly distributed at the interfaces between ferrite and Fe{sub 2}B. Adding 1.5 wt.% Cr or 1.8 wt.% Ni to Fe–0.4B–0.5C steel completely changes the Fe{sub 2}B and Fe{sub 3}C phases to a M{sub 3}(B,C) phase, where M represents the metallic elements, including Fe, Cr, Mo, and Ni. Furthermore, Cr, Mo, B, and C atoms tend to concentrate on the M{sub 3}(B,C) phase, but Ni atoms do not. - Highlights: • Network structures consisting of ferrite, Fe{sub 2}B boride, and Fe{sub 3}C carbide were extensively observed in the Fe–0.4B–0.5C steel. • Adding 1.5 wt.% Cr or 1.8 wt.% Ni to Fe–0.4B–0.5C steel completely transforms the Fe{sub 2}B and Fe{sub 3}C phases to a M{sub 3}(B,C) phase. • Cr, Mo, B, and C atoms tend to concentrate on the M{sub 3}(B,C) phase, but Ni atoms do not.« less

Improving the environmental profile of wood panels via co-production of ethanol and acetic acid.

PubMed

Earles, J Mason; Halog, Anthony; Shaler, Stephen

2011-11-15

The oriented strand board (OSB) biorefinery is an emerging technology that could improve the building, transportation, and chemical sectors' environmental profiles. By adding a hot water extraction stage to conventional OSB panel manufacturing, hemicellulose polysaccharides can be extracted from wood strands and converted to renewably sourced ethanol and acetic acid. Replacing fossil-based gasoline and acetic acid has the potential to reduce greenhouse gas (GHG) emissions, among other possible impacts. At the same time, hemicellulose extraction could improve the environmental profile of OSB panels by reducing the level of volatile organic compounds (VOCs) emitted during manufacturing. In this study, the life cycle significance of such GHG, VOC, and other emission reductions was investigated. A process model was developed based on a mix of laboratory and industrial-level mass and energy flow data. Using these data a life cycle assessment (LCA) model was built. Sensitive process parameters were identified and used to develop a target production scenario for the OSB biorefinery. The findings suggest that the OSB biorefinery's deployment could substantially improve human and ecosystem health via reduction of select VOCs compared to conventionally produced OSB, gasoline, and acetic acid. Technological advancements are needed, however, to achieve desirable GHG reductions.

Novel Routes for Sintering of Ultra-high Temperature Ceramics and their Properties

DTIC Science & Technology

2014-10-31

UHTCs charge (zirconium and hafnium borides , SiC) with additives (chromium carbide, nickel, chromium, etc.), which activate sintering process, is...temperature phases in a form of carboborides of zirconium and bi borides of zirconium or chromium. Elevation of densification rate of sintered borides is...superplasticity under the slip mechanism of zirconium boride and silica carbide grains on grain boundary interlayers with nanocrystalline grains of carbon

Endoscopic surgery for the antenatal treatment of myelomeningocele: the CECAM trial.

PubMed

Pedreira, Denise A L; Zanon, Nelci; Nishikuni, Koshiro; Moreira de Sá, Renato A; Acacio, Gregório L; Chmait, Ramen H; Kontopoulos, Eftichia V; Quintero, Rubén A

2016-01-01

A recent randomized clinical trial named Management of Myelomeningocele Study (MOMS trial) showed that prenatal correction of open spina bifida (OSB) via open fetal surgery was associated with improved infant neurological outcomes relative to postnatal repair, but at the expense of increased maternal morbidity. We sought to report the final results of our phase I trial (Cirurgia Endoscópica para Correção Antenatal da Meningomielocele [CECAM]) on the feasibility, safety, potential benefits, and side effects of the fetoscopic treatment of OSB using our unique surgical technique. Ten consecutive pregnancies with lumbosacral OSB were enrolled in the study. Surgeries were performed percutaneously under general anesthesia with 3 ports and partial carbon dioxide insufflation. After appropriate surgical positioning of the fetus, the neuroplacode was released with scissors and the skin was undermined to place a biocellulose patch over the lesion. The skin was closed over the patch using a single running stitch. Preoperative, postoperative, and postnatal magnetic resonance imaging were performed to assess hindbrain herniation. Neurodevelopmental evaluation was performed before discharge and at 3, 6, and 12 months. All cases were delivered by cesarean delivery, at which time the uterus was assessed for evidence of thinning or dehiscence. The median gestational age at the time of surgery was 27 weeks (range 25-28 weeks). Endoscopic repair was completed in 8 of 10 fetuses. Two cases were unsuccessful due to loss of uterine access. The mean gestational age at birth was 32.4 weeks with a mean latency of 5.6 weeks between surgery and delivery (range 2-8 weeks). There was 1 fetal and 1 neonatal demise, and 1 unsuccessful case underwent postnatal repair. Of the 7 infants available for analysis, complete reversal of hindbrain herniation occurred in 6 of 7 babies. Three babies required ventriculoperitoneal shunting or third ventriculostomy. Functional motor level was the same or better than the anatomical level in 6 of 7 cases. There was no significant maternal morbidity and no evidence of myometrial thinning or dehiscence. However, surgeries were complicated by premature rupture of membrane and prematurity. Our study suggests that the antenatal treatment of OSB using a fetoscopic approach and our unique surgical technique can result in a watertight seal, reversal of the hindbrain herniation, and better than expected motor function. Our technique differs substantially from the classic repair of OSB used in prior open fetal surgery and fetoscopic studies, in which the dura mater is dissected and the defect is closed in multiple layers. Instead, we use a biocellulose patch placed over the lesion and simple closure of the skin. As such, our technique is an alternative to the current paradigms in the antenatal treatment of OSB. Our clinical outcomes are in line with the results of our extensive prior animal work. Maternal benefits of our approach and technique include minimal morbidity and no myometrial legacy. Current limitations of the approach include potential loss of access, premature rupture of membranes, and attendant prematurity. Phase II trials are needed to prevent these complications and to further assess the risks and benefits of our distinct surgical approach and technique. Copyright © 2016 Elsevier Inc. All rights reserved.

Ultrasonic Characterization of Superhard Material: Osmium Diboride

NASA Astrophysics Data System (ADS)

Yadawa, P. K.

2012-12-01

Higher order elastic constants have been calculated in hexagonal structured superhard material OsB2 at room temperature following the interaction potential model. The temperature variation of the ultrasonic velocities is evaluated along different angles with unique axis of the crystal using the second order elastic constants. The ultrasonic velocity decreases with the temperature along particular orientation with the unique axis. Temperature variation of the thermal relaxation time and Debye average velocities are also calculated along the same orientation. The temperature dependency of the ultrasonic properties is discussed in correlation with elastic, thermal and electrical properties. It has been found that the thermal conductivity is the main contributor to the behaviour of ultrasonic attenuation as a function of temperature and the responsible cause of attenuation is phonon-phonon interaction. The mechanical properties of OsB2 at low temperature are better than at high temperature, because at low temperature it has low ultrasonic velocity and ultrasonic attenuation. Superhard material OsB2 has many industrial applications, such as abrasives, cutting tools and hard coatings.

Slater-Pauling behavior within quaternary intermetallic borides of the Ti{sub 3}Co{sub 5}B{sub 2} structure-type

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burghaus, Jens; Dronskowski, Richard, E-mail: drons@HAL9000.ac.rwth-aachen.d; Miller, Gordon J.

2009-10-15

First-principles, density-functional studies of several intermetallic borides of the general type M{sub 2}M'Ru{sub 5-n}Rh{sub n}B{sub 2} (n=0-5; M=Sc, Ti, Nb; M'=Fe, Co) show that the variation in saturation magnetic moment with valence-electron count follows a Slater-Pauling curve, with a maximum moment occurring typically at 66 valence electrons. The magnetic moments in these compounds occur primarily from the 3d electrons of the magnetically active M' sites, with some contribution from the Ru/Rh sites via magnetic polarization. Electronic DOS curves reveal that a rigid-band approach is a reasonable approximation for the estimation of saturation moments and the analysis of orbital interactions inmore » this family of complex borides. COHP analyses of the M'-M' orbital interactions indicate optimized interactions in the minority spin states for Co-containing phases, but strong bonding interactions remaining in Fe-containing phases. - Graphical abstract: Theoretically determined (spin-polarized LMTO-GGA) local magnetic moments as a function of the chemical valence Z for various intermetallic borides.« less

Designing superhard metals: The case of low borides

NASA Astrophysics Data System (ADS)

Liang, Yongcheng; Qin, Ping; Jiang, Haitao; Zhang, Lizhen; Zhang, Jing; Tang, Chun

2018-04-01

The search for new superhard materials has usually focused on strong covalent solids. It is, however, a huge challenge to design superhard metals because of the low resistance of metallic bonds against the formation and movement of dislocations. Here, we report a microscopic mechanism of enhancing hardness by identifying highly stable thermodynamic phases and strengthening weak slip planes. Using the well-known transition-metal borides as prototypes, we demonstrate that several low borides possess unexpectedly high hardness whereas high borides exhibit an anomalous hardness reduction. Such an unusual phenomenon originates from the peculiar bonding mechanisms in these compounds. Furthermore, the low borides have close compositions, similar structures, and degenerate formation energies. This enables facile synthesis of a multiphase material that includes a large number of interfaces among different borides, and these interfaces form nanoscale interlocks that strongly suppress the glide dislocations within the metal bilayers, thereby drastically enhancing extrinsic hardness and achieving true superhard metals. Therefore, this study not only elucidates the unique mechanism responsible for the anomalous hardening in this class of borides but also offers a valid alchemy to design novel superhard metals with multiple functionalities.

Cost comparison between ultrasound-guided 14-g large core breast biopsy and open surgical biopsy: an analysis for Austria.

PubMed

Gruber, R; Walter, E; Helbich, T H

2010-06-01

To examine the budget impact of ultrasound-guided 14-g large core breast biopsy (US-guided LCBB) by comparing the costs of US-guided LCBB and open surgical biopsy (OSB); to calculate the cost savings attributable to US-guided LCBB; and to assess the frequency with which US-guided LCBB obviates the need for an OSB. In a retrospective study, we reviewed 399 suspicious breast lesions on which US-guided LCBB and OSB or, in cases of benign histology, clinical follow-up, were performed. Cost savings were calculated using nationally allowed flat rates (A-drg) and patient charges. Costs were measured from both, a hospital and a socioeconomic perspective. Deterministic sensitivity analyses were simulated to assess the extent of achievable cost savings. Overall cost savings for US-guided LCBB over OSB were euro 977 (euro 2,337/euro 3,314) per case from a hospital perspective, resulting in a total cost decrease of 30% for the diagnosis of suspicious breast lesions. From a socioeconomic perspective, cost savings were euro 1,542 (euro 2,600/euro 4,142) per case, resulting in a 37% reduction in biopsy cost. US-guided LCBB obviated the need for a surgical procedure in 240 (60%) of 399 women. In all four sensitivity analyses, costs of US-guided LCBB remained lower than that of OSB. From an economic perspective, US-guided LCBB is highly recommended for the diagnosis of suspicious breast lesions, as this procedure reduces the cost of diagnosis substantially. In Austria, annual cost savings would be euro 18.5 million. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

Designing Superhard Materials by Incorporating Boron Into Heavy Transition Metals

NASA Astrophysics Data System (ADS)

Liang, Yongcheng; Li, Anhu; Zhao, Jianzhi; Zhang, Wenqing

First-principles calculations on the incompressibility, elasticity and hardness of the Os, OsB2, Re, and ReB2 materials have systematically been performed by the plane-wave basis pseudopotential method. Transition metals Os and Re, which have high bulk modulus but low hardness, can be converted into hard materials by combining them with small B atoms. Moreover, electronic and structural mechanisms of ReB2 and OsB2 are analyzed in detail and compared. It is shown that incorporating small B atoms into heavy transition metals should be a valid pathway to obtain new superhard materials.

Kinetics of electrolysis current reversal boriding of tool steels in a boron-containing oxychloride melt based on CaCl2

NASA Astrophysics Data System (ADS)

Chernov, Ya. B.; Filatov, E. S.

2017-08-01

The kinetics of thermal diffusion boriding in a melt based on calcium chloride with a boron oxide additive is studied using reversed current. The main temperature, concentration, and current parameters of the process are determined. The phase composition of the coating is determined by a metallographic method.

Can bread processing conditions alter glycaemic response?

PubMed

Lau, Evelyn; Soong, Yean Yean; Zhou, Weibiao; Henry, Jeyakumar

2015-04-15

Bread is a staple food that is traditionally made from wheat flour. This study aimed to compare the starch digestibility of western baked bread and oriental steamed bread. Four types of bread were prepared: western baked bread (WBB) and oriental steamed bread (OSB), modified baked bread (MBB) made with the OSB recipe and WBB processing, and modified steamed bread (MSB) made with the WBB recipe and OSB processing. MBB showed the highest starch digestibility in vitro, followed by WBB, OSB and MSB. A similar trend was observed for glycaemic response in vivo. MBB, WBB, OSB and MSB had a glycaemic index of 75±4, 71±5, 68±5 and 65±4, respectively. Processing differences had a more pronounced effect on starch digestibility in bread, and steamed bread was healthier in terms of glycaemic response. The manipulation of processing conditions could be an innovative route to alter the glycaemic response of carbohydrate-rich foods. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reactive multilayer synthesis of hard ceramic foils and films

DOEpatents

Makowiecki, Daniel M.; Holt, Joseph B.

1996-01-01

A method for synthesizing hard ceramic materials such as carbides, borides nd aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coild as a tape for later use.

Identification of Bacillus subtilis men mutants which lack O-succinylbenzoyl-coenzyme A synthetase and dihydroxynaphthoate synthase.

PubMed Central

Meganathan, R; Bentley, R; Taber, H

1981-01-01

Menaquinone (vitamin K2)-deficient mutants of Bacillus subtilis, whose growth requirement is satisfied by 1,4-dihydroxy-2-naphthoic acid but not by o-succinylbenzoic acid (OSB), have been analyzed for enzymatic defects. Complementation analysis of cell-free extracts of the mutants revealed that there are two groups, as already indicated by genetic analysis. The missing enzyme in each group was identified by complementation of the cell-free extracts with o-succinylbenzoyl-coenzyme A (CoA) synthetase and dihydroxynaphthoate synthase extracted from Mycobacterium phlei. Mutants found to lack dihydroxynaphthoate synthase, and which therefore complement with dihydroxynaphthoate synthase of M. phlei, were designated as menB; those lacking o-succinylbenzoyl-CoA synthetase, and therefore complementing with o-succinylbenzoyl-CoA synthetase, were designated as menE. The menB mutants RB413 (men-325) and RB415 (men-329), when incubated with [2,3-14C2]OSB, produced only the spirodilactone form of OSB in a reaction that was CoA and adenosine 5'-triphosphate dependent. PMID:6780515

Determination of multi-GNSS pseudo-absolute code biases and verification of receiver tracking technology

NASA Astrophysics Data System (ADS)

Villiger, Arturo; Schaer, Stefan; Dach, Rolf; Prange, Lars; Jäggi, Adrian

2017-04-01

It is common to handle code biases in the Global Navigation Satellite System (GNSS) data analysis as conventional differential code biases (DCBs): P1-C1, P1-P2, and P2-C2. Due to the increasing number of signals and systems in conjunction with various tracking modes for the different signals (as defined in RINEX3 format), the number of DCBs would increase drastically and the bookkeeping becomes almost unbearable. The Center for Orbit Determination in Europe (CODE) has thus changed its processing scheme to observable-specific signal biases (OSB). This means that for each observation involved all related satellite and receiver biases are considered. The OSB contributions from various ionosphere analyses (geometry-free linear combination) using different observables and frequencies and from clock analyses (ionosphere-free linear combination) are then combined on normal equation level. By this, one consistent set of OSB values per satellite and receiver can be obtained that contains all information needed for GNSS-related processing. This advanced procedure of code bias handling is now also applied to the IGS (International GNSS Service) MGEX (Multi-GNSS Experiment) procedure at CODE. Results for the biases from the legacy IGS solution as well as the CODE MGEX processing (considering GPS, GLONASS, Galileo, BeiDou, and QZSS) are presented. The consistency with the traditional method is confirmed and the new results are discussed regarding the long-term stability. When processing code data, it is essential to know the true observable types in order to correct for the associated biases. CODE has been verifying the receiver tracking technologies for GPS based on estimated DCB multipliers (for the RINEX 2 case). With the change to OSB, the original verification approach was extended to search for the best fitting observable types based on known OSB values. In essence, a multiplier parameter is estimated for each involved GNSS observable type. This implies that we could recover, for receivers tracking a combination of signals, even the factors of these combinations. The verification of the observable types is crucial to identify the correct observable types of RINEX 2 data (which does not contain the signal modulation in comparison to RINEX 3). The correct information of the used observable types is essential for precise point positioning (PPP) applications and GNSS ambiguity resolution. Multi-GNSS OSBs and verified receiver tracking modes are essential to get best possible multi-GNSS solutions for geodynamic purposes and other applications.

Computational-Experimental Processing of Boride/Carbide Composites by Reactive Infusion of Hf Alloy Melts into B4C

DTIC Science & Technology

2015-09-16

AFRL-AFOSR-VA-TR-2015-0314 Computational -Experimental Processing of Boride /Carbide Composites by Reactive Infusion of Hf Alloy Melts into B4C...Computational -Experimental Processing of Boride /Carbide Composites by Reactive Infusion of Hf Alloy Melts into B4C 5a.  CONTRACT NUMBER 5b.  GRANT...with a packed bed of B4C to form boride - carbide precipitates. Although the ultimate goal of the research endeavor is to enhance significantly the

Crystal structures and compressibility of novel iron borides Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} synthesized at high pressure and high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bykova, E., E-mail: elena.bykova@uni-bayreuth.de; Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth; Gou, H.

2015-10-15

We present here a detailed description of the crystal structures of novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} with various iron content (x=1.01(1), 1.04(1), 1.32(1)), synthesized at high pressures and high temperatures. As revealed by high-pressure single-crystal X-ray diffraction, the structure of Fe{sub 2}B{sub 7} possesses short incompressible B–B bonds, which make it as stiff as diamond in one crystallographic direction. The volume compressibility of Fe{sub 2}B{sub 7} (the bulk modulus K{sub 0}= 259(1.8) GPa, K{sub 0}′= 4 (fixed)) is even lower than that of FeB{sub 4} and comparable with that of MnB{sub 4}, known for highmore » bulk moduli among 3d metal borides. Fe{sub x}B{sub 50} adopts the structure of the tetragonal δ-B, in which Fe atoms occupy an interstitial position. Fe{sub x}B{sub 50} does not show considerable anisotropy in the elastic behavior. - Graphical abstract: Crystal structures of novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} (x=1.01(1), 1.04(1), 1.32(1)). - Highlights: • Novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50}, were synthesized under HPHT conditions. • Fe{sub 2}B{sub 7} has a unique orthorhombic structure (space group Pbam). • Fe{sub 2}B{sub 7} possesses short incompressible B–B bonds that results in high bulk modulus. • Fe{sub x}B{sub 50} adopts the structure of the tetragonal δ-B composed of B{sub 12} icosahedra. • In Fe{sub x}B{sub 50} intraicosahedral bonds are stiffer than intericosahedral ones.« less

Effect of borides on hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xuan

To investigate borides effect on the hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel, hot compression tests at the temperatures of 950– 1150 °C and the strain rates of 0.01– 10 s{sup −1} were performed. Flow stress curves indicated that borides increased the material's stress level at low temperature but the strength was sacrificed at temperatures above 1100 °C. A hyperbolic-sine equation was used to characterize the dependence of the flow stress on the deformation temperature and strain rate. The hot deformation activation energy and stress exponent were determined to be 355 kJ/mol and 3.2,more » respectively. The main factors leading to activation energy and stress exponent of studied steel lower than those of commercial 304 stainless steel were discussed. Processing maps at the strains of 0.1, 0.3, 0.5, and 0.7 showed that flow instability mainly concentrated at 950– 1150 °C and strain rate higher than 0.6 s{sup −1}. Results of microstructure illustrated that dynamic recrystallization was fully completed at both high temperature-low strain rate and low temperature-high strain rate. In the instability region cracks were generated in addition to cavities. Interestingly, borides maintained a preferential orientation resulting from particle rotation during compression. - Highlights: •The decrement of activation energy was affected by boride and boron solution. •The decrease of stress exponent was influenced by composition and Cottrell atmosphere. •Boride represented a preferential orientation caused by particle rotation.« less

Field free, directly heated lanthanum boride cathode

DOEpatents

Leung, Ka-Ngo; Moussa, D.; Wilde, S.B.

1987-02-02

A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic field which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

Methods of repairing a substrate

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2011-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium boride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Interfacial reactions in borsic/Ti-3Al-2-1/2V composite

NASA Technical Reports Server (NTRS)

Rao, V. B.; Houska, C. R.; Unnam, J.; Brewer, W. D.; Tenney, D. R.

1979-01-01

The paper provides a detailed X-ray characterization of a borsic/Ti-3Al-2-1/2V composite, and to correlate the relative intensities of the reaction products with the mechanical properties. Based on X-ray integrated intensity data two stages of interface reactions were identified: during the first stage there is a simultaneous interdiffusion of Si, C, and Ti atoms at the filament/matrix interface resulting in the formation of Ti5Si3, TiSi and small amounts of TiSi2 and TiC. The second stage is associated with considerable TiSi2 and boride formation. It appears that the alpha-phase of Ti is more reactive in forming silicides and borides than the beta-phase. The silicide intensities and the reaction zone thicknesses are shown to be directly related to the reduction of the ultimate tensile strength by thermal degradation, and the results indicate that silicide reaction products are as detrimental to strength as the borides.

Simplified Methods for Improving the Blast Resistance of Cold-Formed Steel Walls

DTIC Science & Technology

2011-01-01

sheathing products such as oriented strand board ( OSB ) offer a level of blast resistance that may be effective in mitigating lower-level blast...considered in order to keep designs to a minimum cost. Standard sheathing materials such as OSB , gypsum and plywood— as well as specially selected sheathing...commercially available clip connectors. Sheathing materials such as gypsum and OSB are brittle and have significantly lower capacity than sheet steel

Brain stem/brain stem occipital bone ratio and the four-line view in nuchal translucency images of fetuses with open spina bifida.

PubMed

Iuculano, Ambra; Zoppi, Maria Angelica; Piras, Alessandra; Arras, Maurizio; Monni, Giovanni

2014-09-10

Abstract Objective: Brain stem depth/brain stem occipital bone distance (BS/BSOB ratio) and the four-line view, in images obtained for nuchal translucency (NT) screening in fetuses with open spina bifida (OSB). Methods: Single center, retrospective study based on the assessment of NT screening images of fetuses with OSB. A ratio between the BS depth and the BSOB distance was calculated (BS/BSOB ratio) and the four-line view observed, and the sensitivity for a BS/BSOB ratio superior/equal to 1, and for the lack of detection of the four-line view were calculated. Results: There were 17 cases of prenatal diagnosis OSB. In six cases, the suspicion on OSB was raised during NT screening, in six cases, the diagnosis was made before 20 weeks and in five cases during anomaly scan. The BS/BSOB ratio was superior/equal to 1 in all 17 cases, and three lines, were visualized in 15/17 images of the OSB cases, being the sensitivity 100% (95% CI, 81 to 100%) and 88% (95% CI, 65 to 96%). Conclusion: Assessment of BS/BSOB ratio and four-line view in NT images is feasible detecting affected by OSB with high sensitivity. The presence of associated anomalies or of an enlarged NT enhances the early detection.

Sonographic detection of open spina bifida in the first trimester: review of the literature.

PubMed

Meller, César; Aiello, Horacio; Otaño, Lucas

2017-07-01

In the beginnings, sonographic diagnosis of open spina bifida (OSB) relied on the meticulous scanning of the fetal vertebrae for abnormalities but many defects were missed. After the mid-1980s, however, with the description of the intracranial findings in the second trimester (the "lemon sign" and the "banana sign"), the prenatal diagnosis of OSB was enhanced. In the last 2 decades, there has been widespread uptake of routine ultrasound examination in the first trimester of pregnancy with the purpose of the measurement of fetal crown-rump length to determine gestational age, to screen for trisomy 21 and other aneuploidies, mainly with the nuchal translucency, and for diagnosis of many major abnormalities. Many papers were published focusing on early diagnosis of myelomeningocele (MMC), and the objective of this review is to summarize the different techniques described regarding prenatal diagnosis of OSB in the first trimester of pregnancy.

A case of oral spelling behavior: another environmental dependency syndrome.

PubMed

Ragno Paquier, Claire; Assal, Frédéric

2007-12-01

To present the case of a woman with a probable vascular dementia and a unique oral spelling behavior (OSB). Our aim was to better characterize the mechanisms underlying OSB in this patient with advanced cognitive and noncognitive deficits. Different kind of language deficits have been described in dementias and other related diseases. Other nonaphasic acquired communication disorders include a heterogeneous group of verbal impairment that are mainly due to attentional and executive impairments. We describe the neurolinguistic and neuropsychologic analysis of an 88-year-old woman with spontaneous OSB. Computed tomography-scan at the time of the clinical analysis is also presented. OSB occurred preferentially in spontaneous discourse, manifested in other language tasks, concerned all lexical categories, and was not accompanied by spelling deficit although language was not intact and disclosed foreign accent syndrome. Environmental dependency syndrome or utilization behavior was prominent and concerned various sensorimotor activities. We postulate that OSB was not secondary to a linguistic or more specifically to a spelling deficit but to another variant of environmental dependency syndrome and probably associated with a cortico-subcortical lesion including the left prefrontal region.

Electroplating of the superconductive boride MgB2 from molten salts

NASA Astrophysics Data System (ADS)

Abe, Hideki; Yoshii, Kenji; Nishida, Kenji; Imai, Motoharu; Kitazawa, Hideaki

2005-02-01

An electroplating technique of the superconductive boride MgB2 onto graphite substrates is reported. Films of MgB2 with a thickness of tens micrometer were fabricated on the planar and curved surfaces of graphite substrates by means of electrolysis on a mixture of magnesium chloride, potassium chloride, sodium chloride, and magnesium borate fused at 600 °C under an Ar atmosphere. The electrical resistivity and magnetization measurements revealed that the electroplated MgB2 films undergo a superconducting transition with the critical temperature (Tc) of 36 K.

Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

NASA Technical Reports Server (NTRS)

Tanaka, Hidehiko

1987-01-01

A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

Prospective sonographic detection of spina bifida at 11-14 weeks and systematic literature review.

PubMed

Orlandi, Emanuela; Rossi, Cinzia; Perino, Antonio; Cucinella, Gaspare; Orlandi, Francesco

2016-01-01

To conduct a literature review to assess the effectiveness of first trimester ultrasonographic markers of spina bifida (SB) integrating data with our prospective experience. The analysis of the SB cases that we prospectively detected in the first trimester, between January 2012 and February 2014, and a systematic review of all the papers evaluating the effectiveness of SB ultrasonographic markers at 11-14 weeks, namely brain stem diameter (BS), fourth ventricle/intracranial translucency (IT), cisterna magna (CM), brain stem/occipital bone distance (BSOB), the ratio between BS and BSOB. Some studies assess only the effectiveness of IT, others include more parameters, and few include them all. We prospectively detected four SB cases, three open (OSB) and one closed (CSB), in a low risk population undergoing first trimester screening. In the three OSB, CM (in 2/3 cases) and BSOB (3/3) distance were below the 5th percentile, BS and BS/BSOB ratio (3/3) were above the 95th percentile. In the CSB, all the measurements were within normal limits. The literature and our data agree that most fetuses with OSB demonstrate in the first trimester positive sonographic markers in the posterior fossa, but additional prospective studies are needed to establish the best protocol for OSB screening.

The Effects of Borides on the Mechanical Properties of TLPB Repaired Inconel 738 Superalloy

NASA Astrophysics Data System (ADS)

Wei, J.; Ye, Y.; Sun, Z.; Zou, G.; Bai, H.; Wu, A.; Liu, L.

2017-10-01

The transient liquid phase diffusion bonding (TLPB) method was used to repair an artificial crack in Inconel 738, which was notched by a femtosecond laser. Mixed ratios of BNi-1a:DF-4B were investigated at the bonding temperature of 1373 K (1100 °C) for 2 to 36 hours. The effect of borides on the mechanical properties of TLPB repaired joints was studied through analysis of the microstructure, fracture path, and morphology observations. The borides formation, morphology, distribution, and joints strength were studied in detail. The results showed that the diffusion of B can either increase or decrease the joint strength, depending on its distribution and morphology. The amount of large blocky Ni-B compounds in the precipitate zone were reduced with increasing holding time, which resulted in an increase in joint strength. Nevertheless, further increasing the holding time led to a decrease in joint strength because of the formation of continuous acicular borides in the diffusion-affected zone. The fracture modes of TLPB joints were also discussed on the basis of the microstructure and fractography.

Magnetization Analysis of Magnesium Boride Wires

NASA Astrophysics Data System (ADS)

Cave, J. R.; Zhu, W.

2006-03-01

Cycled applied field magnetization curves contain a wealth of information on critical current density and flux pinning that is not commonly exploited. Detailed magnetization data for magnesium boride wire cores have been analyzed for critical state model consistency. The iron-sheathed silicon nitride doped magnesium boride wires were prepared from pure magnesium and boron powders with nano-scale silicon nitride additions (MgB2-x(Si3N4)x/7 with x = 0 - 0.4). A subsequent short annealing heat treatment, 800 degrees C and of 1 hour duration in Argon, was applied to create the desired phase. Magnetization critical current densities were up to ˜340 kA/cm2 at 5K and 1T. Major and minor loop analysis will be described, for field sweeps up to 3 tesla at fixed temperatures and for temperature sweeps from 5K to 45K in fixed fields, with respect to parameters describing the critical state model.

Reactive multilayer synthesis of hard ceramic foils and films

DOEpatents

Makowiecki, D.M.; Holt, J.B.

1996-02-13

A method is disclosed for synthesizing hard ceramic materials such as carbides, borides and aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coiled as a tape for later use.

Optimal Power Allocation for Downstream xDSL With Per-Modem Total Power Constraints: Broadcast Channel Optimal Spectrum Balancing (BC-OSB)

NASA Astrophysics Data System (ADS)

Le Nir, Vincent; Moonen, Marc; Verlinden, Jan; Guenach, Mamoun

2009-02-01

Recently, the duality between Multiple Input Multiple Output (MIMO) Multiple Access Channels (MAC) and MIMO Broadcast Channels (BC) has been established under a total power constraint. The same set of rates for MAC can be achieved in BC exploiting the MAC-BC duality formulas while preserving the total power constraint. In this paper, we describe the BC optimal power allo- cation applying this duality in a downstream x-Digital Subscriber Lines (xDSL) context under a total power constraint for all modems over all tones. Then, a new algorithm called BC-Optimal Spectrum Balancing (BC-OSB) is devised for a more realistic power allocation under per-modem total power constraints. The capacity region of the primal BC problem under per-modem total power constraints is found by the dual optimization problem for the BC under per-modem total power constraints which can be rewritten as a dual optimization problem in the MAC by means of a precoder matrix based on the Lagrange multipliers. We show that the duality gap between the two problems is zero. The multi-user power allocation problem has been solved for interference channels and MAC using the OSB algorithm. In this paper we solve the problem of multi-user power allocation for the BC case using the OSB algorithm as well and we derive a computational efficient algorithm that will be referred to as BC-OSB. Simulation results are provided for two VDSL2 scenarios: the first one with Differential-Mode (DM) transmission only and the second one with both DM and Phantom- Mode (PM) transmissions.

Vitamin K2 (menaquinone) biosynthesis in Escherichia coli: evidence for the presence of an essential histidine residue in o-succinylbenzoyl coenzyme A synthetase.

PubMed Central

Bhattacharyya, D K; Kwon, O; Meganathan, R

1997-01-01

o-Succinylbenzoyl coenzyme A (OSB-CoA) synthetase, when treated with diethylpyrocarbonate (DEP), showed a time-dependent loss of enzyme activity. The inactivation follows pseudo-first-order kinetics with a second-order rate constant of 9.2 x 10(-4) +/- 1.4 x 10(-4) microM(-1) min(-1). The difference spectrum of the modified enzyme versus the native enzyme showed an increase in A242 that is characteristic of N-carbethoxyhistidine and was reversed by treatment with hydroxylamine. Inactivation due to nonspecific secondary structural changes in the protein and modification of tyrosine, lysine, or cysteine residues was ruled out. Kinetics of enzyme inactivation and the stoichiometry of histidine modification indicate that of the eight histidine residues modified per subunit of the enzyme, a single residue is responsible for the enzyme activity. A plot of the log reciprocal of the half-time of inactivation against the log DEP concentration further suggests that one histidine residue is involved in the catalysis. Further, the enzyme was partially protected from inactivation by either o-succinylbenzoic acid (OSB), ATP, or ATP plus Mg2+ while inactivation was completely prevented by the presence of the combination of OSB, ATP, and Mg2+. Thus, it appears that a histidine residue located at or near the active site of the enzyme is essential for activity. When His341 present in the previously identified ATP binding motif was mutated to Ala, the enzyme lost 65% of its activity and the Km for ATP increased 5.4-fold. Thus, His341 of OSB-CoA synthetase plays an important role in catalysis since it is probably involved in the binding of ATP to the enzyme. PMID:9324253

Analysis of Deformation Substructures in a Notched LCF Sample Under Dwell Condition in a Ni-Based Superalloy (PREPRINT)

DTIC Science & Technology

2012-08-01

interior, and carbides and borides at the grain boundaries. Blocky carbide particles can also be seen in the grain interior (Figure 1b). The borides ...can be seen distributed (b) higher magnification image of a typical grain boundary decorated with carbide and boride particles. Bi-modal distribution

Future Directions for Selected Topics in Physics and Materials Science

DTIC Science & Technology

2012-07-12

referred to as lightides (e.g. borides , nitrides, phosphides) • Materials for energy conversion, energy storage, energy transport and energy production...Distributed nanosystems and sensors • Strategy for multilayered combinatorics • lightides ( borides , nitrides, phosphides, • New applications for...Strategy for multilayered combinatorics Lightides ( borides , nitrides, phosphides) • Energy conversion, .storage and production • Precision control

Structure of superhard tungsten tetraboride: A missing link between MB2 and MB12 higher borides

PubMed Central

Lech, Andrew T.; Turner, Christopher L.; Mohammadi, Reza; Tolbert, Sarah H.; Kaner, Richard B.

2015-01-01

Superhard metals are of interest as possible replacements with enhanced properties over the metal carbides commonly used in cutting, drilling, and wear-resistant tooling. Of the superhard metals, the highest boride of tungsten—often referred to as WB4 and sometimes as W1–xB3—is one of the most promising candidates. The structure of this boride, however, has never been fully resolved, despite the fact that it was discovered in 1961—a fact that severely limits our understanding of its structure–property relationships and has generated increasing controversy in the literature. Here, we present a new crystallographic model of this compound based on refinement against time-of-flight neutron diffraction data. Contrary to previous X-ray–only structural refinements, there is strong evidence for the presence of interstitial arrangements of boron atoms and polyhedral bonding. The formation of these polyhedra—slightly distorted boron cuboctahedra—appears to be dependent upon the defective nature of the tungsten-deficient metal sublattice. This previously unidentified structure type has an intermediary relationship between MB2 and MB12 type boride polymorphs. Manipulation of the fractionally occupied metal and boron sites may provide insight for the rational design of new superhard metals. PMID:25733870

Design of cemented tungsten carbide and boride-containing shields for a fusion power plant

NASA Astrophysics Data System (ADS)

Windsor, C. G.; Marshall, J. M.; Morgan, J. G.; Fair, J.; Smith, G. D. W.; Rajczyk-Wryk, A.; Tarragó, J. M.

2018-07-01

Results are reported on cemented tungsten carbide (cWC) and boride-containing composite materials for the task of shielding the centre column of a superconducting tokamak power plant. The shield is based on five concentric annular shells consisting of cWC and water layers of which the innermost cWC shield can be replaced with boride composites. Sample materials have been fabricated changing the parameters of porosity P, binder alloy fraction f binder and boron weight fraction f boron. For the fabricated materials, and other hypothetical samples with chosen parameters, Monte Carlo studies are made of: (i) the power deposition into the superconducting core, (ii) the fast neutron and gamma fluxes and (iii) the attenuation coefficients through the shield for the deposited power and neutron and gamma fluxes. It is shown that conventional Co-based cWC binder alloy can be replaced with a Fe–Cr alloy (92 wt.% Fe, 8 wt.% Cr), which has lower activation than cobalt with minor changes in shield performance. Boride-based composite materials have been prepared and shown to give a significant reduction in power deposition and flux, when placed close to the superconducting core. A typical shield of cemented tungsten carbide with 10 wt.% of Fe–8Cr binder and 0.1% porosity has a power reduction half-length of 0.06 m. It is shown that the power deposition increases by 4.3% for every 1% additional porosity, and 1.7% for every 1 wt.% additional binder. Power deposition decreased by 26% for an initial 1 wt.% boron addition, but further increases in f boron showed only a marginal decrease. The dependences of power deposited in the core, the maximum neutron and gamma fluxes on the core surface, and the half attenuation distances through the shield have been fitted to within a fractional percentage error by analytic functions of the porosity, metallic binder alloy and boron weight fractions.

Ultrasonic characterization of engineering performanace of oriented strandboard

NASA Astrophysics Data System (ADS)

Vun, Ronnie Yunheu

Direct-contact (DC) and non-contact (NC) ultrasonic transmission (UT) methods were developed to characterize the structural performance of oriented strandboard (OSB). The UT variable velocity was shown to be sensitive to the physical impediments caused by flake interfacial boundaries and embedded voids. Both attenuation and root mean square (RMS) voltage were good indicators of the "zero void" densification level for OSB, a point of the greatest transmissivity of the stress wave energy. For both DC and NC methods, the predicted densities of the model were validated for spatial distribution over each OSB type. Based on the control limits of +/-10% of the panel average density, density prediction improved with higher resin content (RC) and higher nominal density (ND) levels. From the out-of-limits plots, the predicted in-situ densities produced a reasonably spatial coherence to the measured values. All panels made with ND 0.60 g/cm3 or greater conformed well within the limits, with declining conformity towards lower RC panels. For each composite type made of different particle sizes, the equilibrium moisture content showed a decreasing trend toward smaller particle panels. The attenuation and RMS were good indicators for moisture change and densification level for each composite type. The velocity, sensitive to physical resistance of particle sizes, increased with increasing IB strength and sample density, manifesting the positive influence of layering, resin content, and the negative effect of bark as a constituent. The results of the creep rupture tests on commercial OSB using an acoustic emission (AE) technique indicated that the cumulative AE event count parameter was highly correlated with deflection parameter and appropriately represented the accumulation of incipient damage. Under high stress levels, specimens with high moisture content (MC) sustained the worse damages having the shortest creep rupture time followed by specimens with dynamically rising MC. Defects on the compression-side of the bending specimen were found critical to creep rupture than those on the tension-side. The in-plane fracture patterns tended to follow the defect trenches of low-density valleys, and worsened with greater variability of the horizontal density, indicating the need to measure and control the horizontal density variation within reasonable limits.

Microstructure and mechanical properties of Ni and Fe-base boride-dispersion-strengthened microcrystalline alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wade, C.S.; Park, H.G.; Hoagland, R.G.

This paper considers the relation between microstructure and mechanical properties of two Ni-base and two Fe-base Boride-Dispersion-Strengthened Microcrystalline (BDSM) alloys. In these very fine grained materials the borides were primarily Cr, Mo, and MoFe in a fcc matrix in three of the alloys, and a bcc in one of the Fe-base alloys. Strength data and resistance to stress corrosion cracking are reported and, in the latter case, extraordinary resistance to SCC in NaCl, Na{sub 2}S{sub 2}O{sub 3} and boiling MgCl{sub 2} environments was observed in every case. The fcc BDSM alloys also demonstrated excellent thermal stability in terms of strengthmore » and fracture roughness up to 1000 C. The bcc alloy suffered severe loss of toughness. The fracture mode involved ductile rupture in all alloys and they display a reasonably linear correlation between K{sub Ic} and the square root of particle spacing.« less

Plasma metallurgical production of nanocrystalline borides and carbides

NASA Astrophysics Data System (ADS)

Galevsky, G. V.; Rudneva, V. V.; Cherepanov, A. N.; Galevsky, S. G.; Efimova, K. A.

2016-09-01

he experience in production and study of properties of nanocrystalline borides and chromium carbides, titanium, silicon was summarized. The design and features of the vertical three-jet once-through reactor with power 150 kW, used in the plasma metallurgical production, was described. The technological, thermotechnical and resource characteristics of the reactor were identified. The parameters of borides and carbides synthesis, their main characteristics in the nanodispersed state and equipment-technological scheme of production were provided. Evaluation of engineering-and-economical performance of the laboratory and industrial levels of borides and carbides production and the state corresponding to the segment of the world market was carried out.

Suppression of Boride Formation in Transient Liquid Phase Bonding of Pairings of Parent Superalloy Materials with Different Compositions and Grain Structures and Resulting Mechanical Properties

NASA Astrophysics Data System (ADS)

Steuer, Susanne; Singer, Robert F.

2014-07-01

Two Ni-based superalloys, columnar grained Alloy 247 and single-crystal PWA1483, are joined by transient liquid phase bonding using an amorphous brazing foil containing boron as a melting point depressant. At lower brazing temperatures, two different morphologies of borides develop in both base materials: plate-like and globular ones. Their ratio to each other is temperature dependent. With very high brazing temperatures, the deleterious boride formation in Alloy 247 can be totally avoided, probably because the three-phase-field moves to higher alloying element contents. For the superalloy PWA1483, the formation of borides cannot be completely avoided at high brazing temperatures as incipient melting occurs. During subsequent solidification of these areas, Chinese-script-like borides precipitate. The mechanical properties (tensile tests at room and elevated temperatures and short-term creep rupture tests at elevated temperatures) for brazed samples without boride precipitation are very promising. Tensile strengths and creep times to 1 pct strain are comparable, respectively, higher than the ones of the weaker parent material for all tested temperatures and creep conditions (from 90 to 100 pct rsp. 175 to 250 pct).

Efficient human face detection in infancy.

PubMed

Jakobsen, Krisztina V; Umstead, Lindsey; Simpson, Elizabeth A

2016-01-01

Adults detect conspecific faces more efficiently than heterospecific faces; however, the development of this own-species bias (OSB) remains unexplored. We tested whether 6- and 11-month-olds exhibit OSB in their attention to human and animal faces in complex visual displays with high perceptual load (25 images competing for attention). Infants (n = 48) and adults (n = 43) passively viewed arrays containing a face among 24 non-face distractors while we measured their gaze with remote eye tracking. While OSB is typically not observed until about 9 months, we found that, already by 6 months, human faces were more likely to be detected, were detected more quickly (attention capture), and received longer looks (attention holding) than animal faces. These data suggest that 6-month-olds already exhibit OSB in face detection efficiency, consistent with perceptual attunement. This specialization may reflect the biological importance of detecting conspecific faces, a foundational ability for early social interactions. © 2015 Wiley Periodicals, Inc.

Droplet evaporation and spread on waxy and hairy leaves associated with type and concentration of adjuvants.

PubMed

Xu, Linyun; Zhu, Heping; Ozkan, H Erdal; Bagley, William E; Krause, Charles R

2011-07-01

Adjuvants can improve pesticide application efficiency and effectiveness. However, quantifications of the adjuvant-amended pesticide droplet actions on foliage, which could affect application efficiencies, are largely unknown. Droplet evaporation rates and spread on waxy or hairy leaves varied greatly with the adjuvant types tested. On waxy leaves, the wetted areas of droplets containing crop oil concentrate (COC) were significantly smaller than those containing modified seed oil (MSO), non-ionic surfactant (NIS) or oil surfactant blend (OSB), whereas the evaporation rates of COC-amended droplets were significantly higher. On hairy leaves, COC-amended droplets remained on top of the hairs without wetting the epidermis. When the relative concentration was 1.50, the wetted area of droplets with NIS was 9.2 times lower than that with MSO and 6.1 times lower than that with OSB. The wetted area increased as the adjuvant concentration increased. MSO- or OSB-amended droplets spread extensively on the hairy leaf surface until they were completely dried. These results demonstrated that the proper concentration of MSO, NIS or OSB in spray mixtures improved the homogeneity of spray coverage on both waxy and hairy leaf surfaces and could reduce pesticide use. This article is a US Government work and is in the public domain in the USA. Published 2011 by John Wiley & Sons, Ltd.

Enhanced Gene Expression Rather than Natural Polymorphism in Coding Sequence of the OsbZIP23 Determines Drought Tolerance and Yield Improvement in Rice Genotypes

PubMed Central

Dey, Avishek; Samanta, Milan Kumar; Gayen, Srimonta; Sen, Soumitra K.; Maiti, Mrinal K.

2016-01-01

Drought is one of the major limiting factors for productivity of crops including rice (Oryza sativa L.). Understanding the role of allelic variations of key regulatory genes involved in stress-tolerance is essential for developing an effective strategy to combat drought. The bZIP transcription factors play a crucial role in abiotic-stress adaptation in plants via abscisic acid (ABA) signaling pathway. The present study aimed to search for allelic polymorphism in the OsbZIP23 gene across selected drought-tolerant and drought-sensitive rice genotypes, and to characterize the new allele through overexpression (OE) and gene-silencing (RNAi). Analyses of the coding DNA sequence (CDS) of the cloned OsbZIP23 gene revealed single nucleotide polymorphism at four places and a 15-nucleotide deletion at one place. The single-copy OsbZIP23 gene is expressed at relatively higher level in leaf tissues of drought-tolerant genotypes, and its abundance is more in reproductive stage. Cloning and sequence analyses of the OsbZIP23-promoter from drought-tolerant O. rufipogon and drought-sensitive IR20 cultivar showed variation in the number of stress-responsive cis-elements and a 35-nucleotide deletion at 5’-UTR in IR20. Analysis of the GFP reporter gene function revealed that the promoter activity of O. rufipogon is comparatively higher than that of IR20. The overexpression of any of the two polymorphic forms (1083 bp and 1068 bp CDS) of OsbZIP23 improved drought tolerance and yield-related traits significantly by retaining higher content of cellular water, soluble sugar and proline; and exhibited decrease in membrane lipid peroxidation in comparison to RNAi lines and non-transgenic plants. The OE lines showed higher expression of target genes-OsRab16B, OsRab21 and OsLEA3-1 and increased ABA sensitivity; indicating that OsbZIP23 is a positive transcriptional-regulator of the ABA-signaling pathway. Taken together, the present study concludes that the enhanced gene expression rather than natural polymorphism in coding sequence of OsbZIP23 is accountable for improved drought tolerance and yield performance in rice genotypes. PMID:26959651

Histologic work-up of non-palpable breast lesions classified as probably benign at initial mammography and/or ultrasound (BI-RADS category 3).

PubMed

Gruber, R; Jaromi, S; Rudas, M; Pfarl, G; Riedl, C C; Flöry, D; Graf, O; Sickles, E A; Helbich, T H

2013-03-01

To determine the accuracy of a probably benign assessment of non-palpable breast lesions (BI-RADS category 3) at mammography and/or ultrasound with immediate histological work-up. Stereotactic or ultrasound guided core needle breast biopsy (NBB) was performed to evaluate 288 lesions, which were prospectively assessed as BI-RADS category 3. Imaging findings included 195 masses, 73 calcification cases, 16 focal asymmetries, and four architectural distortion cases. After NBB, patients underwent either open surgical biopsy (OSB) (n=204) or mammographic follow-up (n=84) for at least 24 months. Histological results of NBB were compared with those of OSB. Three of the 288 lesions (1.0%) proved to be malignant at histological work-up, two of them were ductal carcinoma in situ (DCIS) and one of them was an invasive carcinoma. NBB revealed invasive carcinoma in 1/288 (0.35%) and atypical ductal hyperplasia (ADH) in 13/288 (4.5%) lesions. OSB revealed DCIS in 2/204 (1%) and invasive carcinoma in 1/204 (0.5%) lesions. The two DCIS were underestimated as ADH by NBB. The remaining 285 (99%) lesions proved to be benign at OSB or remained stable during follow-up. Confirmed by tissue diagnosis, the low likelihood of malignancy of prospectively assessed probably benign lesions is below the 2% threshold established for BI-RADS category 3. Imaging follow-up is a safe and effective alternative to immediate histological work-up for such lesions. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Effect of heating rate on thermal cracking characteristics and kinetics of Xinjiang oil sand bitumen by TG-FTIR

NASA Astrophysics Data System (ADS)

Hao, Junhui; Zhang, Jinhong; Qiao, Yingyun; Tian, Yuanyu

2017-08-01

This work was aimed to investigate effects of heating rate on thermal cracking behaviors, distribution of gaseous products and activation energy of the thermal cracking process of Xinjiang oil sand bitumen (OSB). The thermal cracking experiments of Xinjiang OSB were performed by using thermogravimetric analyzer (TGA) at various heating rates of 10, 20, 50, 80 and 120 K/min. The evolving characteristic of gaseous products produced from the thermal cracking process was evaluated by the Fourier transform infrared spectrometry (FTIR) connected with TG. The kinetic parameters of the thermal cracking process of Xinjiang OSB at each of heating rate were determined by the Coats-Redfern model. The result show that the temperature intervals of DE volatilization stage and main reaction stage, the ((dw/dt) max and Tmax in thermal cracking process of Xinjiang OSB all increased with the increasing heating rate. While the heating rate has not obvious effect on the coke yield of Xinjiang OSB. Furthermore, the maximum absorbance of gaseous products and corresponding temperature became larger as the heating rate increases. The activation energy of this two stage both presented increasing trend with the rising heating rate, while the increasing content of that of DE volatilization stage was weaker compared to that of main reaction stage.

Microstructure Evolution and Composition Control during the Processing of Thin-gage Metallic Foil (Preprint)

DTIC Science & Technology

2012-02-01

the presence of somewhat randomly-distributed carbides and borides (white particles in BSE images), this grain size was comparable to that observed...pinned by carbide/ boride particles (imaging white in Figure 8c). The very fine gamma-prime precipitates likely produced during magnetron sputtering...sputtered material. First, the carbide/ boride particles were nucleated and hence located preferentially at the grain boundaries in the sputtered

Novel Routes to Tune Thermal Conductivities and Thermoelectric Properties of Materials

DTIC Science & Technology

2012-11-15

expand the possibilities of borides as functional compou nds. A series of indium-free novel TCO compounds with novel crystal structures, has...powerful methods for modification were demonstrated in the borides , silicides and oxides. Introduction: The goal of this project is to...the possibility to modify the crystal structures can expand the possibilities of borides as functional compounds. A series of indium-free novel TCO

Effect of Heat Treatment on Borides Precipitation and Mechanical Properties of CoCrFeNiAl1.8Cu0.7B0.3Si0.1 High-Entropy Alloy Prepared by Arc-Melting and Laser-Cladding

NASA Astrophysics Data System (ADS)

Zhang, H.; Tang, H.; He, Y. Z.; Zhang, J. L.; Li, W. H.; Guo, S.

2017-11-01

Effects of heat treatment on borides precipitation and mechanical properties of arc-melted and laser-cladded CoCrNiFeAl1.8Cu0.7B0.3Si0.1 high-entropy alloys were comparatively studied. The arc-melted alloy contains lots of long strip borides distributed in the body-centered cubic phase, with a hardness about 643 HV0.5. Laser-cladding can effectively inhibit the boride precipitation and the laser-cladded alloy is mainly composed of a simple bcc solid solution, with a high hardness about 769 HV0.5, indicating the strengthening effect by interstitial boron atoms is greater than the strengthening by borides precipitation. Heat treatments between 800°C and 1200°C can simultaneously improve the hardness and fracture toughness of arc-melted alloys, owing to the boride spheroidization, dissolution, re-precipitation, and hence the increased boron solubility and nano-precipitation in the bcc solid solution. By contrast, the hardness of laser-cladded alloys reduce after heat treatments in the same temperature range, due to the decreased boron solubility in the matrix.

Syntheses of super-hard boron-rich solids in the B-C-N-O system

NASA Astrophysics Data System (ADS)

Hubert, Herve Pierre

Alpha-rhombohedral (alpha-rh.) B-rich materials belonging to the B-C-N-O system were prepared using high-pressure, high-temperature techniques. The samples were synthesized using a multianvil device and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and parallel electron energy-loss spectroscopy (PEELS). In the B-O system, the formation of BsbxO materials produced from mixtures of B and Bsb2Osb3 between 1 to 10 GPa and 1000 to 1800sp°C was investigated. Graphitic and diamond-like Bsb2O, reported in previous studies, were not detected. The refractory boron suboxide, nominally Bsb6O, which has the alpha-rh. B structure, is the dominant suboxide in the P and T range of our investigation. High-pressure techniques were used successfully to synthesize boron suboxide of improved purity and crystallinity, and less oxygen-deficient (i.e., closer to the nominal Bsb6O composition) in comparison to room-pressure syntheses. Quantitative analyses indicate compositions of Bsb6Osb{0.95} and Bsb6Osb{0.77} for high-pressure and room-pressure samples, respectively. The first preparation, between 4 to 5.5 GPa, of Bsb6O in which the preferred form of the material is as macroscopic near-perfect regular icosahedra (to 30 mum in diameter) is reported. The Bsb6O icosahedra are similar to the multiply-twinned particles observed in some cubic materials. However, a major difference is that Bsb6O has a rhombohedral structure that closely fits the geometrical requirements for obtaining icosahedral twins. The Bsb6O grains are neither 3D-periodic nor quasicrystalline. Their formation can be described as a Mackay packing of icosahedral Bsb{12} units and provides an alternative to crystal formation by propagation of translational symmetry. Icosahedral twins ranging from 20 nm to 30 mum in diameter, as well as micron-sized euhedral crystals (to 40 mum) were prepared. The structural similarity of compounds with the alpha-rh. B structure is thought to lead to solid solution. In the B-C-O system, intermediate phases were prepared showing evidence of solid solution between Bsb4C and Bsb6O. Boron carbide crystals containing a significant amount of O, typically Bsb6Csb{1.1}Osb{0.33} and Bsb6Csb{1.28}Osb{0.31}, were grown to 20 mum in diameter from mixtures in which B and C were reacted with excess Bsb2Osb3 at 7.5 GPa and 1700sp°C. Cyclic five-fold twins or twins that approximate Bsb6O icosahedra were observed, but the cell dimensions of the B-C-O materials preclude the formation of icosahedral twins. Nanorods with composition near Bsb6C with minor O were grown in a Bsb2Osb3 melt. The mechanism controlling the growth of the nanorods is similar to the solution-liquid-solid (SLS) process. The first conclusive bulk synthesis of a new boron nitride, Bsb6Nsb1-x, was obtained by reacting B and hexagonal BN at 7.5 GPa and 1700sp°C. XRD and PEELS substantiate that this material has a structure related to that of alpha-rh. B and chemical analysis of this compound showed an average composition of Bsb6Nsb{0.92}.

Certain physical properties of cobalt and nickel borides

NASA Technical Reports Server (NTRS)

Kostetskiy, I. I.; Lvov, S. N.

1981-01-01

The temperature dependence of the electrical resistivity, the thermal conductivity, and the thermal emf of cobalt and nickel borides were studied. In the case of the nickel borides the magnetic susceptibility and the Hall coefficient were determined at room temperature. The results are discussed with allowance for the current carrier concentration, the effect of various mechanisms of current-carrier scattering and the location of the Fermi level in relation to the 3d band.

[Ultrasound measurement of fetal posterior fossa at 11 to 13⁺⁶ gestational weeks for screening open spina bifida].

PubMed

Qin, Feng-Zhen; Li, Sheng-Li; Wen, Hua-Xuan; Ouyang, Yu-Rong; Zheng, Qiong; Bi, Jing-Ru

2014-06-01

To establish the normal reference ranges of transabdominal ultrasound measurements of the posterior fossa structure in fetuses at 11 to 13⁺⁶ gestational weeks and explore their clinical value in screening open spina bifida (OSB). Between January, 2013 and September, 541 randomly selected normal fetuses underwent nuchal translucency at the gestational age 11 to 13⁺⁶ weeks. The parameters of the posterior fossa were measured in mid-sagittal view of the fetal face and the axial view of the transverse cerebellum insonated through the anterior fontanel by transabdominal ultrasound to establish the normal reference ranges. The measurements were obtained from 3 fetuses with OSB for comparison with the reference ranges. In normal fetuses, the parameters of the posterior fossa measured in the two views showed no significant differences (P>0.05). Two high echogenic lines were observed in normal fetuses, as compared with one in fetuses with OSB representing the posterior border of the brain stem and the anterior border of the fourth ventricle. The line between the posterior border of the fourth ventricle and the anterior border of the cisterna magna was not displayed in fetuses with OSB. The anteroposterior diameters of the brain stem, the fourth ventricle, and cisterna magna all increased in positive correlation with the crown-lump length in normal fetuses. In the 3 OSB fetuses, the anteroposterior diameter of the brain stem exceeded the 95th percentile and the anteroposterior diameter of fourth ventrical-cisterner magena was below the 5th percentile of the reference range for CRL; the brain stem to fourth ventrical-cisterner magena anteroposterior diameter ratio was increased to above 1. The established normal reference ranges of the parameters of fetal posterior fossa may provide assistance in early OSB detection. The absence of the posterior border of the fourth ventricle and the anterior border of the cisterna magna and a brainstem to fourth ventrical-cisterner magena anteroposterior diameter ratio greater than 1 can be indicative of OSB at 11 to 13⁺⁶ gestational weeks.

Nitrogen dioxide absorption in aqueous sodium sulfite

NASA Astrophysics Data System (ADS)

Shen, Chen Hua

The Clean Air Act of 1990 requires additional reduction of acid gases, sulfur dioxide, and nitrogen oxides released into the atmosphere from coal-fired electric power plants. In the case of older existing power plants, a possible retrofit strategy is to oxidize nitric oxide (NO, the major constituent of NOsbX in flue gas) to nitrogen dioxide (NOsb2) by the addition of methanol or other hydrocarbons into the duct at an optimum temperature regime. NOsb2 can then be removed by either modifying existing SOsb2 control equipment or by adding a limestone (CaCOsb3) slurry scrubbing process. Limestone reacts with SOsb2 to from CaSOsb3, and the free sulfite (SO{sb3sp{=}}) in the solution is reactive toward NOsb2. The focus of this research is to study the reaction between NOsb2 and aqueous sulfite at elevated temperature and in the presence of gas phase Osb2. The removal of NOsb2 by limestone slurry scrubbing involves the reaction between NOsb2 and SO{sb3sp{=}}, bisulfite (HSO{sb3sp{-}}) and water. The reactions between NOsb2 and SO{sb3sp{=}}/HSO{sb3sp{-}} are first order in both reactants, while the NOsb2-water reaction is second order in NOsb2 concentration. The rate constants of the above reactions and the NOsb2-thiosulfate (Ssb2O{sb3sp{=}}) reaction were determined at 55sp°C. SO{sb3sp{=}} was found to be the most reactive toward NOsb2, while the contribution of chemical reaction still dominated in the absorption of NOsb2 into water. The effect of gas phase SOsb2 and Osb2, and liquid phase additives such as Ssb2O{sb3sp{=}}, Casp{++}, Mgsp{++}, and Clsp{-} on NOsb2 absorption was also investigated. The absorption of NOsb2 catalyzes free radical reactions that lead to sulfite oxidation. A semi-empirical model was proposed to relate the rate of sulfite oxidation to the rate of NOsb2 absorption. Thiosulfate inhibits sulfite oxidation by providing an alternative route for the termination of the free radical reactions, and a fundamental model was derived to quantify the effect of Ssb2O{sb3sp{=}} on sulfite oxidation. The absorption of NOsb2 into aqueous bisulfide (HSsp{-}) was studied in an attempt to discover alternative scrubbing technologies. The reaction between NOsb2 and HSsp{-} is twice as fast as the NOsb2-SO{sb3sp{=}} reaction at 55sp°C. A semi-empirical model was proposed to relate NOsb2 absorption to HSsp{-} oxidation. This study has shown that acceptable level of NOsb2 removal by a conventional limestone slurry scrubber is not probable. However, aqueous scrubbing of NOsb2 by Nasb2SOsb3 and Nasb2S solutions are viable options. Furthermore, significant reduction in hold tank liquid depth and/or oxidizing air stoichiometry is possible by NOsb2 injection.

Deposition and characterization of aluminum magnesium boride thin film coatings

NASA Astrophysics Data System (ADS)

Tian, Yun

Boron-rich borides are a special group of materials possessing complex structures typically comprised of B12 icosahedra. All of the boron-rich borides sharing this common structural unit exhibit a variety of exceptional physical and electrical properties. In this work, a new ternary boride compound AlMgB14, which has been extensively studied in bulk form due to its novel mechanical properties, was fabricated into thin film coatings by pulsed laser deposition (PLD) technology. The effect of processing conditions (laser operating modes, vacuum level, substrate temperature, and postannealing, etc.) on the composition, microstructure evolution, chemical bonding, and surface morphology of AlMgB14 thin film coatings has been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectrometry; the mechanical, electrical, and optical properties of AlMgB14 thin films have been characterized by nanoindentation, four-point probe, van der Pauw Hall measurement, activation energy measurement, and UV-VIS-NIR spectrophotometer. Experimental results show that AlMgB14 films deposited in the temperature range of 300 K - 873 K are amorphous. Depositions under a low vacuum level (5 x 10-5 Torr) can introduce a significant amount of C and O impurities into AlMgB14 films and lead to a complex oxide glass structure. Orthorhombic AlMgB14 phase cannot be obtained by subsequent high temperature annealing. By contrast, the orthorhombic AlMgB 14 crystal structure can be attained via high temperature-annealing of AlMgB14 films deposited under a high vacuum level (< 3 x 10-6 Torr), accompanied by strong texture formation. Low vacuum level-as deposited AlMgB14 films have low hardness (10 GPa), but high vacuum level-as deposited AlMgB14 films exhibit an extremely high hardness (45 GPa - 51 GPa), and the higher deposition temperature results in still higher hardness. Furthermore, a very low friction coefficient (0.04 - 0.05) has been observed for high vacuum level-as deposited AlMgB14 films, which could be ascribed to the in situ formation of a surface self-lubricating layer. Unlike most boron-rich boride films, high vacuum level-as deposited AlMgB14 films also possess a low n-type electrical resistivity, which is a consequence of high carrier concentration and moderate carrier mobility. The operative electrical transport mechanism and doping behavior for high vacuum level-as deposited AlMgB14 films are discussed in detail in this thesis.

Finding the Stable Structures of WxN1-x with an ab-initio High-Throughput Approach

DTIC Science & Technology

2014-03-13

cubic boron nitride[4], carbonitrides,[5] and transition metal borides .[6, 7] Over the past several years there has been considerable theoretical...include ionic and covalent structures which seem chemically similar to W-N. These include borides , carbides, oxides, and other nitrides. In this paper we...metallic alloys, [23–27] we extended it to include over fifty new structures. These include nitrides, oxides, borides , and carbides. The important

Magnesium Aluminum Borides as Explosive Materials

DTIC Science & Technology

2011-12-20

Metal Silicides , and Metal Borides by Chemical Vapour Deposition Using Single Organometallic Precursors,” Trans. Inst. Met. Finishing, 72, 127-129...391 (2003). 62. X. Xiaojing, D. Bohua, Q. Zuanhui, and L. Yuanhui, “ Preparation and Synthesis Mechanism of Li-B Alloy,” Rare Metal Materials and...SUPPLEMENTARY NOTES 14. ABSTRACT Metal boride.; and boroo carbide Witted l’"irh Al ’I\\· ere compared co B. Mg. Al Mg:-AJ and Si a.s poteotia! fuel ad.diti

Life cycle assessment of oriented strand boards (OSB): from process innovation to ecodesign.

PubMed

Benetto, Enrico; Becker, Marko; Welfring, Joëlle

2009-08-01

Oriented strand boards (OSBs) are wood panels that are used worldwide mainly in the packaging and the building sectors. Their market share is rapidly increasing thanks to their outstanding mechanical properties and to a renewed interest for wood based products. The OSB production process generates, nonetheless, emissions of volatile organic compounds (VOCs) during the air-drying of wood strands. This known problem in the literature leads to an odorous nuisance in the surrounding area of the production site. In order to address this problem, a novel application to wood drying of an innovative vapor drying technology is successfully operated at the production site of Kronospan Luxembourg S.A. In addition to the reduced odorous nuisance, a significant environmental added value is expected because of the other modifications induced by the vapor-drying technique on the OSB production process viz. the reduced energy and raw materials demands and the change of adhesive mixture, with the addition of phenol resin. The potential impact of this technology on the OSB market is therefore very significant. This study was aimed at assessing the environmental added value provided by the vapor-drying technique through a life cycle assessment (LCA) according to ISO 14040-44 standards. The objective was to compare the environmental performances of the former and the current OSB production processes. Considering only the pollutant emissions from the OSB production process, the reduction of climate change impact and human health damage is significant respectively, 15-20% and 50-75%. When the lifecycle processes related to the OSB production are included, the reduction of damages does not exceed 3-7%. Following an uncertainty analysis,this reduction was nevertheless proven to be statistically significant. However, it is observed that the reduction of environmental impacts and damages allowed by the vapor-drying technology is counterbalanced by the change of adhesive mixture. Indeed the new adhesive mixture generates higher environmental damages than the former mixture because of the higher energy and raw material demand from phenol resin production. These results show the need to move from an approach focused on a single process innovation (the vapor-drying technique) to a more general and systemic approach combining process and product ecodesign. Such approaches are needed in order to effectively improve the overall environmental performance of a production system, without transfer of pollution along the lifecycle or offsets of pollution credits. LCA is definitively one of the most pertinent tools to identify improvement opportunities in the comparison of alternative designs from an environmental perspective.

Analysis of boron carbides' electronic structure

NASA Technical Reports Server (NTRS)

Howard, Iris A.; Beckel, Charles L.

1986-01-01

The electronic properties of boron-rich icosahedral clusters were studied as a means of understanding the electronic structure of the icosahedral borides such as boron carbide. A lower bound was estimated on bipolaron formation energies in B12 and B11C icosahedra, and the associated distortions. While the magnitude of the distortion associated with bipolaron formation is similar in both cases, the calculated formation energies differ greatly, formation being much more favorable on B11C icosahedra. The stable positions of a divalent atom relative to an icosahedral borane was also investigated, with the result that a stable energy minimum was found when the atom is at the center of the borane, internal to the B12 cage. If incorporation of dopant atoms into B12 cages in icosahedral boride solids is feasible, novel materials might result. In addition, the normal modes of a B12H12 cluster, of the C2B10 cage in para-carborane, and of a B12 icosahedron of reduced (D sub 3d) symmetry, such as is found in the icosahedral borides, were calculated. The nature of these vibrational modes will be important in determining, for instance, the character of the electron-lattice coupling in the borides, and in analyzing the lattice contribution to the thermal conductivity.

Electrochemical Corrosion Behavior of Spray-Formed Boron-Modified Supermartensitic Stainless Steel

NASA Astrophysics Data System (ADS)

Zepon, Guilherme; Nogueira, Ricardo P.; Kiminami, Claudio S.; Botta, Walter J.; Bolfarini, Claudemiro

2017-04-01

Spray-formed boron-modified supermartensitic stainless steel (SMSS) grades are alloys developed to withstand severe wear conditions. The addition of boron to the conventional chemical composition of SMSS, combined with the solidification features promoted by the spray forming process, leads to a microstructure composed of low carbon martensitic matrix reinforced by an eutectic network of M2B-type borides, which considerably increases the wear resistance of the stainless steel. Although the presence of borides in the microstructure has a very beneficial effect on the wear properties of the alloy, their effect on the corrosion resistance of the stainless steel was not comprehensively evaluated. The present work presents a study of the effect of boron addition on the corrosion resistance of the spray-formed boron-modified SMSS grades by means of electrochemical techniques. The borides fraction seems to have some influence on the repassivation kinetics of the spray-formed boron-modified SMSS. It was shown that the Cr content of the martensitic matrix is the microstructural feature deciding the corrosion resistance of this sort of alloys. Therefore, if the Cr content in the alloy is increased to around 14 wt pct to compensate for the boron consumed by the borides formation, the corrosion resistance of the alloy is kept at the same level of the alloy without boron addition.

Uniformity of plants regenerated from orange (Citrus sinensis Osb.) protoplasts.

PubMed

Kobayashi, S

1987-05-01

Using 25 plants (protoclones) regenerated from orange (Citrus sinensis Osb.) protoplasts, several characters, including leaf and flower morphology, leaf oil, isozyme patterns and chromosome number, were examined. No significant variations in each character were recorded among the protoclones. Uniformity observed among protoclones was identical to that of nucellar seedlings.

Application of Magnetic and Geotechnical Methods for Archaeological Site Investigations

DTIC Science & Technology

2011-07-01

national historic preservation act NRM natural remnant magnetism NS north-south nT nano Tesla ID inside diameter OSB oriented strand board psi...3.4 Soil Box Experiments Compaction tests were conducted by loading soil into a wooden box (1 m3) constructed of oriented strand board ( OSB ) and

High Energy Advanced Thermal Storage for Spacecraft Solar Thermal Power and Propulsion Systems

DTIC Science & Technology

2011-10-12

Vol. 108, No. 6, June 1961, pp. 568-572. 38. Storms, E. and Mueller, B., "Phase Relations and Thermodynamic Properties of Transition Metal Borides ...T., and Naka, S., "Formation Process of Tungsten Borides by Solid State Reaction Between Tungsten and Amorphous Boron," Journal of Materials...Molybdenum- Borides ," Journal of Metals, September 1952, pp. 983-988. 41. Ellis, R.C., “Various Preparations of Elemental Boron,” Proceedings of the 1st

Finding the Stable Structures of N1-xWx with an Ab Initio High-Throughput Approach

DTIC Science & Technology

2015-05-26

W. These include borides , carbides, oxides, and other nitrides. We also invented many structures to mimic the random pattern of vacancies on both the...structures. These include nitrides, oxides, borides , and carbides, as well as supercells of standard structures with atoms removed to mimic the random patter...1930). [15] R. Kiessling and Y. H. Liu, Thermal stability of the chromium, iron, and tungsten borides in streaming ammonia and the existence of a new

Molten Boron Phase-Change Thermal Energy Storage to Augment Solar Thermal Propulsion Systems

DTIC Science & Technology

2011-07-13

Thermodynamic Properties of Transition Metal Borides . I. The Molybdenum-boron system and Elemental Boron," Journal of Physical Chemistry, Vol. 81...February 1977, pp. 318-324. 38Itoh, H., Matsudaira, T., and Naka, S., "Formation Process of Tungsten Borides by Solid State Reaction Between Tungsten...Molybdenum-Boron and Some Properties of The Molybdenum- Borides ," Journal of Metals, September 1952, pp. 983-988. 40Stout, N. D., Mar, R. W., and Boo, W. O

Direct synthesis of magnesium borohydride

DOEpatents

Ronnebro, Ewa Carin Ellinor [Kennewick, WA; Severa, Godwin [Honolulu, HI; Jensen, Craig M [Kailua, HI

2012-04-03

A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Mg(BH.sub.4).sub.2, from the alkaline earth metal boride MgB.sub.2 by hydrogenating the MgB.sub.2 at an elevated temperature and pressure. The boride may also be doped with small amounts of a metal chloride catalyst such as TiCl.sub.3 and/or NiCl.sub.2. The process provides for charging MgB.sub.2 with high pressure hydrogen above at least 70 MPa while simultaneously heating the material to about 350.degree. C. to about 400.degree. C. The method is relatively simple and inexpensive and provides a reversible hydride compound having a hydrogen capacity of at least 11 wt %.

Neuroimaging parameters in early open spina bifida detection. Further benefit in first trimester screening?

PubMed

Iliescu, D; Comănescu, A; Antsaklis, P; Tudorache, Stefania; Ghiluşi, Mirela; Comănescu, Violeta; Paulescu, Daniela; Ceauşu, Iuliana; Antsaklis, A; Novac, Liliana; Cernea, N

2011-01-01

Morphological investigation of the central nervous system (CNS) in fetuses with positive markers for open spina bifida (OSB) detection, visualized by ultrasound during the first trimester of pregnancy. Data from fetuses that underwent routine first trimester ultrasound scan in our center during September 2007-March 2011 and presented abnormal aspects of the fourth ventricle, also referred as intracranial translucency (IT), provided the morphological support to evaluate CNS features. A neuro-histological study of posterior cerebral fossa illustrated anatomical features of the structures involved in the sonographic first trimester detection of neural tube defects. Abnormal IT aspects were found in OSB cases examined in the first trimester, but also in other severe cerebral abnormalities. Brain stem antero-posterior diameter (BS) and brain stem to occipital bone (BSOB) ratio may be more specific for OSB detection. Correlations between histological aspects of posterior brain fossa and ultrasound standard assessment have been made; highlighting the anatomical features involved by the new techniques developed for OSB early detection. Preliminary results show that modern sonographic protocols are capable to detect abnormalities in the morphometry of the posterior brain. First trimester fourth ventricle abnormalities should be followed by careful CNS evaluation because are likely to appear in OSB affected fetuses, but also in other CNS severe anomalies; in such cases, normal BS and BSOB ratio may serve as indirect argument for spine integrity, if specificity is confirmed in large series of fetuses.

A Simple, General Synthetic Route toward Nanoscale Transition Metal Borides.

PubMed

Jothi, Palani R; Yubuta, Kunio; Fokwa, Boniface P T

2018-04-01

Most nanomaterials, such as transition metal carbides, phosphides, nitrides, chalcogenides, etc., have been extensively studied for their various properties in recent years. The similarly attractive transition metal borides, on the contrary, have seen little interest from the materials science community, mainly because nanomaterials are notoriously difficult to synthesize. Herein, a simple, general synthetic method toward crystalline transition metal boride nanomaterials is proposed. This new method takes advantage of the redox chemistry of Sn/SnCl 2 , the volatility and recrystallization of SnCl 2 at the synthesis conditions, as well as the immiscibility of tin with boron, to produce crystalline phases of 3d, 4d, and 5d transition metal nanoborides with different morphologies (nanorods, nanosheets, nanoprisms, nanoplates, nanoparticles, etc.). Importantly, this method allows flexibility in the choice of the transition metal, as well as the ability to target several compositions within the same binary phase diagram (e.g., Mo 2 B, α-MoB, MoB 2 , Mo 2 B 4 ). The simplicity and wide applicability of the method should enable the fulfillment of the great potential of this understudied class of materials, which show a variety of excellent chemical, electrochemical, and physical properties at the microscale. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An alternatively spliced heat shock transcription factor, OsHSFA2dI, functions in the heat stress-induced unfolded protein response in rice.

PubMed

Cheng, Q; Zhou, Y; Liu, Z; Zhang, L; Song, G; Guo, Z; Wang, W; Qu, X; Zhu, Y; Yang, D

2015-03-01

As sessile organisms, plants have evolved a wide range of defence pathways to cope with environmental stress such as heat shock. However, the molecular mechanism of these defence pathways remains unclear in rice. In this study, we found that OsHSFA2d, a heat shock transcriptional factor, encodes two main splice variant proteins, OsHSFA2dI and OsHSFA2dII in rice. Under normal conditions, OsHSFA2dII is the dominant but transcriptionally inactive spliced form. However, when the plant suffers heat stress, OsHSFA2d is alternatively spliced into a transcriptionally active form, OsHSFA2dI, which participates in the heat stress response (HSR). Further study found that this alternative splicing was induced by heat shock rather than photoperiod. We found that OsHSFA2dI is localised to the nucleus, whereas OsHSFA2dII is localised to the nucleus and cytoplasm. Moreover, expression of the unfolded protein response (UNFOLDED PROTEIN RESPONSE) sensors, OsIRE1, OsbZIP39/OsbZIP60 and the UNFOLDED PROTEIN RESPONSE marker OsBiP1, was up-regulated. Interestingly, OsbZIP50 was also alternatively spliced under heat stress, indicating that UNFOLDED PROTEIN RESPONSE signalling pathways were activated by heat stress to re-establish cellular protein homeostasis. We further demonstrated that OsHSFA2dI participated in the unfolded protein response by regulating expression of OsBiP1. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Nano-Disperse Borides and Carbides: Plasma Technology Production, Specific Properties, Economic Evaluation

NASA Astrophysics Data System (ADS)

Galevskii, G. V.; Rudneva, V. V.; Galevskii, S. G.; Tomas, K. I.; Zubkov, M. S.

2016-04-01

The experience of production and study on properties of nano-disperse chromium and titanium borides and carbides, and silicon carbide has been generalized. The structure and special service aspects of utilized plasma-metallurgical complex equipped with a three-jet direct-flow reactor with a capacity of 150 kW have been outlined. Processing, heat engineering and service life characteristics of the reactor are specified. The synthesis parameters of borides and carbides, as well as their basic characteristics in nano-disperse condition and their production flow diagram are outlined. Engineering and economic performance of synthesizing borides in laboratory and industrial conditions is assessed, and the respective segment of the international market as well. The work is performed at State Siberian Industrial University as a project part of the State Order of Ministry of Science and Education of the Russian Federation No. 11.1531/2014/K.

Ceramic material suitable for repair of a space vehicle component in a microgravity and vacuum environment, method of making same, and method of repairing a space vehicle component

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2009-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Synthesis and Characterization of Low-Cost Superhard Transition-Metal Borides

NASA Astrophysics Data System (ADS)

Kaner, Richard

2013-06-01

The increasing demand for high-performance cutting and forming tools, along with the shortcomings of traditional tool materials such as diamond (unable to cut ferrous materials), cubic boron nitride (expensive) and tungsten carbide (relatively-low hardness), has motivated the search for new superhard materials for these applications. This has led us to a new class of superhard materials, dense refractory transition-metal borides, which promise to address some of the existing problems of conventional superhard materials. For example, we have synthesized rhenium diboride (ReB2) using arc melting at ambient pressure. This superhard material has demonstrated an excellent electrical conductivity and superior mechanical properties, including a Vickers hardness of 48.0 GPa (under an applied load of 0.49 N). To further increase the hardness and lower the materials costs, we have begun exploring high boron content metal borides including tungsten tetraboride (WB4) . We have synthesized WB4 by arc melting and studied its hardness and high-pressure behavior. With a similar Vickers hardness (43.3 GPa under a load of 0.49 N) and bulk modulus (326-339 GPa) to ReB2, WB4 offers a lower cost alternative and has the potential to be used in cutting tools. To further enhance the hardness of this superhard metal, we have created the binary and ternary solid solutions of WB4 with Cr, Mn and Ta, the results of which show a hardness increase of up to 20 percent. As with other metals, these metallic borides can be readily cut and shaped using electric discharge machining (EDM).

Past Informing Present: Parallels Between Racial Integration in the Armed Forces and Repeal of Don’t Ask, Don’t Tell

DTIC Science & Technology

2011-02-15

Military (pp. 121- 133). New York, New York: Aldine de Gruyter. Schiefer, M. (2010, October 21). Email Correspondence: Race on OSB . San Antonio TX...M. (2010, October 21). Email Correspondence: Race on OSB . San Antonio TX. 73 Military Leadership Diversity Commission. (n.d.). Recent Enlisted

Use of fire-impacted trees for oriented strandboards

Treesearch

Laura Moya; Jerrold E. Winandy; William T. Y. Tze; Shri Ramaswamy

2008-01-01

This study evaluates the potential use of currently unexploited burnt timber from prescribed burns and wildfires for oriented strandboard (OSB). The research was performed in two phases: in Phase I, the effect of thermal exposure of timber on OSB properties was evaluated. Jack pine (Pinus banksiana) trees variously damaged by a moderately intense prescribed burn in a...

Evaluation of the High-Heel Roof-to-Wall Connection with Extended OSB Wall Sheathing

Treesearch

Andrew DeRenzis; Vladimir Kochkin; Xiping Wang

2013-01-01

A recently completed testing project conducted to evaluate optimized structural roof-to-wall attachment solutions demonstrated the effectiveness of wood structural panels in restraining high-heel trusses against rotation. This study was designed to further evaluate the performance of OSB wall sheathing panels extended over the high-heel truss in resisting combined...

Simultaneous Analysis of Seven Biomarkers of Oxidative Damage to Lipids, Proteins, and DNA in Urine.

PubMed

Martinez, Maria P; Kannan, Kurunthachalam

2018-06-05

The determination of oxidative stress biomarkers (OSBs) is useful for the assessment of health status and progress of diseases in humans. Whereas previous methods for the determination of OSBs in urine were focused on a single marker, in this study, we present a method for simultaneous determination of biomarkers of oxidative damage to lipids, proteins, and DNA. 2,4-Dinitrophenylhydrazine (DNPH) derivatization followed by solid phase extraction (SPE) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) allowed the determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG), o- o'-dityrosine (diY), malondialdehyde (MDA), and four F 2 -isoprostane isomers: 8-iso-prostaglandinF 2α (8-PGF 2α ), 11β-prostaglandinF 2α (11-PGF 2α ), 15( R)-prostaglandinF 2α (15-PGF 2α ), and 8-iso,15( R)-prostaglandinF 2α (8,15-PGF 2α ) in urine. Derivatization with DNPH and SPE was optimized to yield greater sensitivity and selectivity for the analysis of target chemicals. The limits of detection of target analytes in urine were below 30 pg mL -1 . The assay intra- and interday variability was below 16% of the relative standard deviation, and the recoveries of target chemicals spiked into synthetic urine were near 100%. The method was applied to the analysis of 21 real urine samples, and the analytes were found at a detection frequency of 85% for 8-PGF 2α and 15-PGF 2α , 71% for 11-PGF 2α , 81% for 8,15-PGF 2α , and 100% for diY, 8-OHdG, and MDA. This method offers simultaneous determination of multiple OSBs of different molecular origin in urine samples selectively with high accuracy and precision.

On the Correlation between Morphology of alpha and Its Crystallographic Orientation Relationship with TiB and Beta in Boron Containing Ti-5Al-5Mo-5V-3Cr-0.5Fe Alloy (Preprint)

DTIC Science & Technology

2012-01-01

submitted to Metallurgical Transactions. This document contains color. 14. ABSTRACT While the role of borides on the microstructure of titanium...Ohio, U.S.A. Abstract While the role of borides on the microstructure of titanium alloys has been discussed in many previous reports, this paper...morphology of  precipitates nucleating from boride precipitates present in the  matrix of a titanium alloy; and (b) to investigate the role of presence or

Laser-assisted selective fusing of thermal sprayed Ni-based self-fluxing alloys by using high-power diode lasers

NASA Astrophysics Data System (ADS)

Chun, Eun-Joon; Kim, Min-Su; Nishikawa, Hiroshi; Park, Changkyoo; Suh, Jeong

2018-03-01

Fusing treatment of Ni-based self-fluxing alloys (Metco-16C and 1276F) was performed using high-power diode lasers to control the temperature of the substrate's surface in real time. The effects of the fusing treatment temperature on the microstructural change and hardness distribution were also investigated. For Metco-16C and 1276F, the macrostructural inhomogeneity (voids) within the thermal sprayed layer decreased considerably as the fusing temperature increased. For both self-fluxing alloys, the optimal temperature for fusing was approximately 1423 K (for Metco-16C) and 1373 K (for 1276F), both of which are within the solid state temperature range; these temperatures maximize the alloy hardness together with the macrostructural homogeneity. In this temperature range, the microstructure consists of a lamellar-structured matrix phase with fine (<5 μm) carbides and borides. Selective fusing for a thermal sprayed layer 0.2-0.5 mm in thickness could be successfully achieved in a high-power diode laser system.

Using the Workforce Investment Act of 1998 to Benefit Youth with Blindness and Visual Impairment

ERIC Educational Resources Information Center

Mitchell, Patrick J.; Zampitella-Freese, Christina

2003-01-01

Overbrook School for the Blind (OSB), a specialized school serving students with blindness and visual impairment, has provided, since the early 1990s, paid summer work experiences as part of the school's Work Experience Program. In this article, the authors discuss how OSB has strengthened its original program as a result of the Workforce…

Simple and accurate temperature correction for moisture pin calibrations in oriented strand board

Treesearch

Charles Boardman; Samuel V. Glass; Patricia K. Lebow

2017-01-01

Oriented strand board (OSB) is commonly used in the residential construction market in North America and its moisture-related durability is a critical consideration for building envelope design. Measurement of OSB moisture content (MC), a key determinant of durability, is often done using moisture pins and relies on a correlation between MC and the electrical...

Intracranial translucency as a sonographic marker for detecting open spina bifida at 11-13+6 weeks scan: Our experience.

PubMed

Teegala, Madhavi L; Vinayak, Dhamangaonkar G

2017-01-01

The fourth ventricle, seen as intracranial translucency (IT) at 11-13 +6 weeks, has been reported to be obliterated in cases of open spina bifida (OSB). Our aim was to assess its role in detecting OSB at 11-13 +6 weeks. This prospective study was conducted at foetal medicine unit from January 2014 to June 2015. All women who underwent both first and mid-trimester scan in our unit were included in the study. IT was categorized as normal, obliterated or not clear. Spine was examined during both scans. Totally, 341 cases were included in the study. IT was found to be obliterated in four cases and not clear in one case. There was demonstrable OSB at 11-13 +6 weeks in two cases, at 15-16 weeks in two cases and at 24 weeks in one case. In the remaining 336 cases with normal IT, spine was found to be normal at target scan. Mid-sagittal view of face that is routinely used to measure nuchal translucency (NT) can also be used to detect OSB. It is feasible to integrate IT into the routine 11-13 +6 weeks scan.

Sister Mary Theresa Brentano, OSB's Innovative Use of Magnetic Audio Tapes: An Overlooked Story in the History of Educational Technology.

ERIC Educational Resources Information Center

Herndon, Linda

This paper tells the story of Sister Mary Theresa Brentano, O.S.B's (1902-1987) innovative use of magnetic audiotapes to provide instruction for students in grades K-12. From 1952 to approximately 1968, Brentano implemented, refined, and tested her tape teaching methods with special emphasis on individualizing instruction in the elementary school.…

Creep behavior of sweetgum OSB: effect of load level and relative humidity

Treesearch

J.H. Pu; R.C. Tang; Chung-Yun Hse

1994-01-01

Flexural creep behavior of laboratory-fabricated sweetgum oriented strandboard (OSB). under constnat (65% and 95%) and cyclic (65% 95% at a 96-hr. frequency) relative humidity (RH) conditions at 75 F (23.9 C) is presented. Two levels (4.5% and 6.5%) of resin content (RC) of phenol-formaldehyde were used in fabricating the test panels. Two load levels (20% and...

Selection of peptides binding to metallic borides by screening M13 phage display libraries.

PubMed

Ploss, Martin; Facey, Sandra J; Bruhn, Carina; Zemel, Limor; Hofmann, Kathrin; Stark, Robert W; Albert, Barbara; Hauer, Bernhard

2014-02-10

Metal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials. In this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni3B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles. This study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni3B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

Nuclear magnetic resonance data of C36H30Br2OSb2

NASA Astrophysics Data System (ADS)

Mikhova, B. M.

This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

Nuclear magnetic resonance data of C36H30Cl2OSb2

NASA Astrophysics Data System (ADS)

Mikhova, B. M.

This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

PubMed Central

Friedrich, Alexandra; Winkler, Björn; Juarez-Arellano, Erick A.; Bayarjargal, Lkhamsuren

2011-01-01

Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p,T) stability, compressibility and hardness is described as obtained from experiments. PMID:28824101

Energy conversion device and method of reducing friction therein

DOEpatents

Solovyeva, Lyudmila Mikhaylovna; Jansson, Kyle S; Elmoursi, Alaa AbdelAzim; Zhu, Dong; Milner, Robert; Daughterty, Early Eugene; Higdon, Clifton Baxter; Elagamy, Kamel Abdel-Khalik; Hicks, Aaron Michael

2013-10-08

A device configured for converting energy includes a first surface, a second surface configured for moving with respect to the first surface during operation of the device, and a coating disposed on at least one of the first surface and the second surface. The coating includes a first layer of a ceramic alloy represented by the general formula AlMgB.sub.14--X, wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the group of Group IV elements and borides and nitrides thereof, and a second layer disposed on the first layer and including carbon in a gradient concentration. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12.

Cryopreservation of nucellar cells of navel orange (Citrus sinensis Osb. var. brasiliensis Tanaka) by vitrification.

PubMed

Sakai, A; Kobayashi, S; Oiyama, I

1990-06-01

The nucellar cells of navel orange(Citrus sinensis Osb. var. brasiliensis Tanaka) were successfully cryopreserved by vitrification. In this method, cells were sufficiently dehydrated with highly concentrated cryoprotective solution(PVS2) prior to direct plunge in liquid nitrogen. The PVS2 contains(w/v) 30% glycerol, 15% ethylene glycol and 15% DMSO in Murashige-Tucker medium(MT) containing 0.15 M sucrose. Cells were treated with 60% PVS2 at 25°C for 5 min and then chilled PVS2 at 0°C for 3 min. The cell suspension of about 0.1 ml was loaded in a 0.5 ml transparent plastic straw and directly plunged in liquid nitrogen for 30 min. After rapid warming, the cell suspension was expelled in 2 ml of MT medium containing 1.2 M sucrose. The average rate of survival was about 80%. The vitrified cells regenerated plantlets. This method is very simple and the time required for cryopreservation is only about 10 min.

Ocean Science for Decision-Making: Current Activities of the National Research Council's Ocean Studies Board

NASA Astrophysics Data System (ADS)

Roberts, S.; Glickson, D.; Mengelt, C.; Forrest, S.; Waddell, K.

2012-12-01

The National Research Council is a private, nonprofit organization chartered by Congress in 1916 as an expansion of the U.S. National Academy of Sciences. Its mission is to improve the use of science in government decision making and public policy, increase public understanding, and promote the acquisition and dissemination of knowledge in matters involving science, engineering, technology, and health. Within the National Research Council, the Ocean Studies Board (OSB) mission is to explore the science, policies, and infrastructure needed to understand, manage, and conserve coastal and marine environments and resources. OSB undertakes studies and workshops on emerging scientific and policy issues at the request of federal agencies, Congress, and others; provides program reviews and guidance; and facilitates communication on oceanographic issues among different sectors. OSB also serves as the U.S. National Committee to the international, nongovernmental Scientific Committee on Oceanic Research (SCOR). OSB has produced reports on a wide range of topics of interest to researchers and educators, the federal government, the non-profit sector, and industry. Recent reports have focused on ecosystem services in the Gulf of Mexico after the Deepwater Horizon oil spill, sea level rise on the U.S. west coast, scientific ocean drilling needs and accomplishments, requirements for sustained ocean color measurements, critical infrastructure for ocean research, tsunami warning and preparedness, ocean acidification, and marine and hydrokinetic power resource assessments. Studies that are currently underway include responding to oil spills in the Arctic, evaluating the effectiveness of fishery stock rebuilding plans, and reviewing the National Ocean Acidification Research Plan. OSB plays an important role in helping create policy decisions and disseminating important information regarding various aspects of ocean science.

Microstructure and High Temperature Mechanical Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Metal Injection Molding Process

NASA Astrophysics Data System (ADS)

Lee, Kee-Ahn; Gwon, Jin-Han; Yoon, Tae-Sik

2018-03-01

This study investigated the microstructure and the room and high temperature mechanical properties of Fe-Cr-B alloy manufactured by metal injection molding. In addition, hot isostatic pressing was performed to increase the density of the material, and a comparison of properties was made. Microstructural observation confirmed a bi-continuous structure composed of a three-dimensional network of α-Fe phase and (Cr,Fe)2B phase. The HIPed specimen featured a well-formed adhesion between the α-Fe phase and boride, and the number of fine pores was significantly reduced. The tensile results confirmed that the HIPed specimen (RT to 900 °C) had higher strengths compared to the as-sintered specimen, and the change of elongation starting from 700 °C was significantly greater in the HIPed specimen. Fractography suggested that cracks propagated mostly along the interface between the α-Fe matrix and boride in the as-sintered specimen, while direct fracture of boride was observed in addition to interface separation in the HIPed specimen.

Synthesis, Structure, and Properties of Refractory Hard-Metal Borides

NASA Astrophysics Data System (ADS)

Lech, Andrew Thomas

As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB2 and WB4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called "super-hard metals".

Superabrasive boride and a method of preparing the same by mechanical alloying and hot pressing

DOEpatents

Cook, Bruce A.; Harringa, Joel L.; Russell, Alan M.

2002-08-13

A ceramic material which is an orthorhombic boride of the general formula: AlMgB.sub.14 :X, with X being a doping agent. The ceramic is a superabrasive, and in most instances provides a hardness of 40 GPa or greater.

Taking precautions at KSC for Hurricane Georges

NASA Technical Reports Server (NTRS)

1998-01-01

Workers put up plywood barriers on the windows of the Operations Support Building (OSB) as part of a precautionary plan in the event that Hurricane Georges threatens Central Florida. In light of the unpredictable nature of hurricanes, the decision was made to minimize risk and provide protection to KSC personnel and to the Space Shuttle national asset. The Vehicle Assembly Building is reflected (left) in the uncovered windows of the OSB.

Intracranial translucency as a sonographic marker for detecting open spina bifida at 11–13+6 weeks scan: Our experience

PubMed Central

Teegala, Madhavi L; Vinayak, Dhamangaonkar G

2017-01-01

Aims and Objectives: The fourth ventricle, seen as intracranial translucency (IT) at 11–13+6 weeks, has been reported to be obliterated in cases of open spina bifida (OSB). Our aim was to assess its role in detecting OSB at 11–13+6 weeks. Materials and Methods: This prospective study was conducted at foetal medicine unit from January 2014 to June 2015. All women who underwent both first and mid-trimester scan in our unit were included in the study. IT was categorized as normal, obliterated or not clear. Spine was examined during both scans. Results: Totally, 341 cases were included in the study. IT was found to be obliterated in four cases and not clear in one case. There was demonstrable OSB at 11–13+6 weeks in two cases, at 15–16 weeks in two cases and at 24 weeks in one case. In the remaining 336 cases with normal IT, spine was found to be normal at target scan. Conclusion: Mid-sagittal view of face that is routinely used to measure nuchal translucency (NT) can also be used to detect OSB. It is feasible to integrate IT into the routine 11–13+6 weeks scan. PMID:29379237

Elective percutaneous coronary intervention without on-site surgical backup: a community hospital experience.

PubMed

Djelmami-Hani, M; Mouanoutoua, Mouatou; Hashim, Abdelazim; Solis, Joaquin; Bergen, Lawrence; Oldridge, Neil; Egbujiobi, Leo C; Allaqaband, Suhail; Akhtar, Masood; Bajwa, Tanvir

2007-12-01

The American College of Cardiology guidelines consider elective percutaneous coronary intervention (PCI) without on-site surgical backup (OSB) a Class-III indication. Our objective was to determine the safety of elective PCI without OSB. The study is a prospective analysis of a cohort of patients who underwent elective PCI without OSB at our institution. All patients were at our community satellite institution in Beloit, Wis. Three hundred twenty-one elective interventions were performed (mean age 64 +/-12, 68% male). The prevalence of diabetes and hypertension was 28% and 82.5% respectively. A predefined protocol was designed to transfer patients to a cardiac surgical facility if necessary. An experienced interventional cardiologist reviewed the diagnostic angiograms. Patients with complex lesions were excluded from the study. Any procedure-related death or emergency coronary artery bypass graft surgery. Three hundred eighty-two vessels were stented. Multi-vessel intervention was performed in 61 patients (19%). Only 5% of lesions were type C. Four hundred thirty-seven stents were deployed. IIb-IIIa inhibitors were used in 77 (24%) cases. Procedural success was 99.7%. There were no deaths, myocardial infarctions nor need for urgent target vessel revascularization at 6 months. With careful patient/lesion selection, an experienced interventional cardiologist and a predefined transfer protocol, elective PCI without OSB can be performed safely.

Exploring the additivity of binaural and monaural masking release

PubMed Central

Hall, Joseph W.; Buss, Emily; Grose, John H.

2011-01-01

Experiment 1 examined comodulation masking release (CMR) for a 700-Hz tonal signal under conditions of NoSo (noise and signal interaurally in phase) and NoSπ (noise in phase, signal out of phase) stimulation. The baseline stimulus for CMR was either a single 24-Hz wide narrowband noise centered on the signal frequency [on-signal band (OSB)] or the OSB plus, a set of flanking noise bands having random envelopes. Masking noise was either gated or continuous. The CMR, defined with respect to either the OSB or the random noise baseline, was smaller for NoSπ than NoSo stimulation, particularly when the masker was continuous. Experiment 2 examined whether the same pattern of results would be obtained for a 2000-Hz signal frequency; the number of flanking bands was also manipulated (two versus eight). Results again showed smaller CMR for NoSπ than NoSo stimulation for both continuous and gated masking noise. The CMR was larger with eight than with two flanking bands, and this difference was greater for NoSo than NoSπ. The results of this study are compatible with serial mechanisms of binaural and monaural masking release, but they indicate that the combined masking release (binaural masking-level difference and CMR) falls short of being additive. PMID:21476663

Metal loaded zeolitic media for the storage and oxidative destruction of chlorinated VOCs

NASA Astrophysics Data System (ADS)

Chintawar, Prashant Shiodas

Industrial solvents such as trichloroethylene (TCE), perchloroethylene (PCE), etc. are suspected carcinogens and are linked to atmospheric and groundwater pollution. Therefore, the destruction and/or safe disposal of these chlorinated volatile organic compounds (CVOCs) is an immediate national need. The objective of this dissertation was to study transition metal (TM) loaded zeolites for adsorption (storage) and subsequent catalytic destruction of CVOCs present in humid air streams. In this study, zeolite Y, ZSM-5 and ETS-10 were modified by introduction of a TM cation to make them suitable as dual function sorbent/catalyst (S/C) media. In order to develop these S/C media, five investigations were carried out. In the first investigation, the activity and selectivity of three catalysts viz., Cr-Y, Co-Y, Co/Alsb2Osb3, was compared for the destruction of CVOCs. Cr-Y was the most promising catalyst with its activity decreasing with an increase in the chlorine content of the CVOC molecule. In the second investigation, in order to elucidate the pathways involved in the destruction of CVOCs, in situ FT-IR studies were carried out on active Cr-Y surfaces at 25, 100 (or 130) and 300sp°C which showed that CVOC destruction proceeded through the formation of oxygenated intermediates (carbonyl, carboxylate, etc.). These investigations showed the necessity of chromium for destruction of CVOCs. However, chromium residues in the spent catalysts are an environmental concern. Therefore, in the third investigation, attempts were made to stabilize low levels of chromium on ZSM-5 zeolites. Thus, Cr-ZSM-5 media of varying SiOsb2/Alsb2Osb3 ratio were evaluated for sorption and destruction of TCE. This investigation led to the development of a Cr-ZSM-5 (SiOsb2/Alsb2Osb3=80,\\ {˜}0.5 wt% chromium) as an efficient S/C medium for TCE destruction. In the fourth investigation, deactivation experiments were carried out on four Cr-ZSM-5 catalysts. Under the conditions used, all the catalysts lost destruction activity and selectivity which was found to be related to the catalyst and CVOC composition. The deactivation was caused by the loss and migration of exchanged chromium cations from the straight channels of ZSM-5. Since the loss of exchanged chromium cations from Cr-ZSM-5 catalyst during CVOC destruction was inevitable, an attempt was made to introduce chromium in the framework of ETS-10 in the final investigation. The resulting Cr-ETS-10 and Cr-ZSM-5 S/C media were then used to evaluate the effect of CVOC chlorine content by determining adsorptivity and reactivity of aliphatic and aromatic hydrocarbons and their chlorinated counterparts. Chlorination was found to increase the hydrocarbon adsorptivity on both S/C media. Characterization of the Cr-ETS-10 revealed that chromium had been introduced into the framework of ETS-10.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitler, Steven J.; Raja, Krishnan S.; Charit, Indrajit

Solid solutions of HfB 2-ZrB 2 mixtures were prepared by high-energy ball milling of diboride and additive powders followed by spark plasma sintering (SPS). A mixture of stoichiometric 1:1 HfB 2-ZrB 2 borides was the base composition to which Hf, Zr, Ta, LaB 6 or Gd 2O 3 was added. Hf, Zr and Ta were added in order to bring the boron-to-metal ratio down to 1.86, rendering the boride as MeB 1.86. In the case of LaB 6 and Gd 2O 3, 1.8 mol% was added. Electroanalytical behavior of hydrogen evolution reactions was evaluated in 1 M H 2SO 4more » and 1 M NaOH solutions. The LaB 6 additive material showed Tafel slopes of 125 and 90 mV/decade in acidic and alkaline solutions respectively. The Hf and Zr rich samples showed Tafel slopes of about 120 mV/decade in both electrolytes. The over potentials of hydrogen evolution reactions (at 10 mA/cm 2) in the alkaline solution were about 100 mV lower than those in acidic solution. The metal-rich diborides and addition of LaB 6 showed better hydrogen evolution reaction (HER) activities than the base 1:1 HfB 2-ZrB 2 stoichiometric diboride solid solution. Furthermore, the higher activity of metal-rich borides could be attributed to the increased electron population at the d-orbitals of the metal shown by band structure modeling calculations using the Density Functional Theory approach.« less

Characterization of an Additive Manufactured TiAl Alloy—Steel Joint Produced by Electron Beam Welding

PubMed Central

Baudana, Giorgio; Lorusso, Massimo; Ugues, Daniele; Fino, Paolo

2018-01-01

In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti3Al followed by Al3NiTi2 and AlNi2Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached. PMID:29342074

Construction of orthogonal synchronized bi-directional field to enhance heating efficiency of magnetic nanoparticles.

PubMed

Chen, Shih-Wei; Lai, Jr-Jie; Chiang, Chen-Li; Chen, Cheng-Lung

2012-06-01

Magnetic hyperthermia using magnetic nanoparticles (MNPs) has attracted considerable attention as one of the promising tumor therapy. The study has been developed under single magnetic field. Recently, we found that the immobile MNP may generate more heat under two synchronous ac magnetic fields than traditional single and circular polarized fields based on model simulation result. According to this finding we constructed an orthogonal synchronized bi-directional field (OSB field). The system contained two LC resonant inverters (L: inductor, C: capacitor) and both vertical and transverse ac magnetic fields were generated by two Helmholtz coils. To reduce the interference, the axis directional of two coils were arranged orthogonally. The experiments showed that the heating ability of aggregated MNPs is greatly enhanced under this newly designed OSB field without increasing the strength of magnetic field. The OSB field system provides a promising way for future clinical hyperthermia.

Cutting needle biopsy combined with immunohistochemical study of myeloperoxidase for the diagnosis of histiocytic necrotizing lymphadenitis.

PubMed

Hanakawa, Hiroyuki; Orita, Yorihisa; Sato, Yasuharu; Takeuchi, Mai; Ohno, Kyotaro; Iwaki, Noriko; Ito, Toshihiro; Nishizaki, Kazunori; Yoshino, Tadashi

2013-12-01

Cutting needle biopsy (CNB) combined with immunohistochemical study of myeloperoxidase (MPO) is a useful minimally invasive diagnostic procedure for histiocytic necrotizing lymphadenitis (HNL). HNL is mainly diagnosed by pathological findings of open surgical biopsy (OSB) specimens. Recently the appearance of anti-MPO positive histiocytes has been reported as a highly specific pathological diagnosis for HNL. Considering the cosmetic impact and burden on the patients, we performed CNB combined with immunohistochemical study of MPO for the diagnosis of HNL. Few studies have reported the utility of this method in the diagnosis of HNL. A retrospective study was conducted using clinical data from 20 HNL patients. CNB was performed in 8 patients and OSB in 13 (OSB after CNB in 1). MPO-positive histiocytes were observed in all of the 20 cases. The accuracy of the diagnoses was finally confirmed by the clinical courses in all cases.

Construction of orthogonal synchronized bi-directional field to enhance heating efficiency of magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Shih-Wei; Lai-Jie, Jr.; Chiang, Chen-Li; Chen, Cheng-Lung

2012-06-01

Magnetic hyperthermia using magnetic nanoparticles (MNPs) has attracted considerable attention as one of the promising tumor therapy. The study has been developed under single magnetic field. Recently, we found that the immobile MNP may generate more heat under two synchronous ac magnetic fields than traditional single and circular polarized fields based on model simulation result. According to this finding we constructed an orthogonal synchronized bi-directional field (OSB field). The system contained two LC resonant inverters (L: inductor, C: capacitor) and both vertical and transverse ac magnetic fields were generated by two Helmholtz coils. To reduce the interference, the axis directional of two coils were arranged orthogonally. The experiments showed that the heating ability of aggregated MNPs is greatly enhanced under this newly designed OSB field without increasing the strength of magnetic field. The OSB field system provides a promising way for future clinical hyperthermia.

Metallic Borides, La 2 Re 3 B 7 and La 3 Re 2 B 5 , Featuring Extensive Boron–Boron Bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bugaris, Daniel E.; Malliakas, Christos D.; Chung, Duck Young

We synthesized La 2Re 3B 7 and La 3Re 2B 5 in single-crystalline form from a molten La/Ni eutectic at 1000°C, in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La 2Re 3B 7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La 3Re 2B 5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. Furthermore, the compounds possess three-dimensional framework structures thatmore » are built up from rhenium boride polyhedra and boron-boron bonding. La 3Re 2B 5 features fairly common B 2 dumbbells, whereas La 2Re 3B 7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La 3Re 2B 5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La 2Re 3B 7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300K of ~ 375 μΩ cm. The electronic band structure calculations also suggest that La 3Re 2B 5 is a regular metal.« less

Metallic Borides, La 2 Re 3 B 7 and La 3 Re 2 B 5 , Featuring Extensive Boron–Boron Bonding

DOE PAGES

Bugaris, Daniel E.; Malliakas, Christos D.; Chung, Duck Young; ...

2016-01-26

We synthesized La 2Re 3B 7 and La 3Re 2B 5 in single-crystalline form from a molten La/Ni eutectic at 1000°C, in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La 2Re 3B 7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La 3Re 2B 5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. Furthermore, the compounds possess three-dimensional framework structures thatmore » are built up from rhenium boride polyhedra and boron-boron bonding. La 3Re 2B 5 features fairly common B 2 dumbbells, whereas La 2Re 3B 7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La 3Re 2B 5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La 2Re 3B 7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300K of ~ 375 μΩ cm. The electronic band structure calculations also suggest that La 3Re 2B 5 is a regular metal.« less

Biosecurity and Open-Source Biology: The Promise and Peril of Distributed Synthetic Biological Technologies.

PubMed

Evans, Nicholas G; Selgelid, Michael J

2015-08-01

In this article, we raise ethical concerns about the potential misuse of open-source biology (OSB): biological research and development that progresses through an organisational model of radical openness, deskilling, and innovation. We compare this organisational structure to that of the open-source software model, and detail salient ethical implications of this model. We demonstrate that OSB, in virtue of its commitment to openness, may be resistant to governance attempts.

[Cost-effectiveness of percutaneous core needle breast biopsy (CNBB) versus open surgical biopsy (OSB) of nonpalpable breast lesions: metaanalysis and cost evaluation for German-speaking countries].

PubMed

Gruber, R; Bernt, R; Helbich, T H

2008-02-01

To analyze the cost-effectiveness of percutaneous image-guided CNBB (stereotactic-/ultrasound-guided; large/vacuum-assisted) of non-palpable breast lesions vs. OSB and to compare and discuss the results reported in the literature with results for German-speaking countries. A key word search in three databases, limited to the period from 1/1994 to 12/2006 was performed. Only original papers were selected. No published articles for German-speaking countries were identified; therefore a comprehensive data collection was made. On the basis of 377 abstracts, nine studies were evaluated for final assessment. The data of German-speaking countries were compared with results reported in the literature. This study demonstrates that CNBB compared to OSB leads to reduction in cost ranging from 51-96 %. The cost reduction depends on biopsy modality and lesion type and is subject to national fluctuations. CNBB can replace a surgical procedure in 71-85 % of cases. Use of CNBB as an alternative to OSB has the potential to substantially reduce healthcare costs. The data are based almost exclusively on the North American literature. A potential cost reduction in the Netherlands and Switzerland confirms these findings. Future work must include cost evaluation studies for German-speaking countries since this is an issue with important national economic ramifications.

Critical current enhancement in large grains of YBa(2)Cu(3)O(7-delta) through microstructural engineering

NASA Astrophysics Data System (ADS)

Chopra, Manoj

High temperature superconductors (HTS) have many potential applications e.g. magnetically levitated trains, power transmission, mechanical energy storage, dent pullers, Nuclear Magnetic Resonance (N.M.R), magnetic resonance imaging (M.R.I) etc. However, one of the most daunting tasks for the applicability of HTS is the enhancement of critical current density (Jc) and flux-pinning at liquid nitrogen temperatures by microstructure design. The addition of Ysb2BaCuOsb5 (211) particles to large grain melt textured YBasb2Cusb3Osb{7-delta} (Y123) have significantly improved the transport and magnetic properties of this material. Here, a systematic quantitative analysis on the effects of the 211 addition was performed on a microscopic scale with a systematic variation in the initial volume percentage of 211. From the correlation between critical current measurements and quantitative microscopy of both (001) and (110) sections, a maximum value of Jc was observed corresponding to a measured Y123 volume percent of 20% ± 3%. Accounting for the loss of liquid phase for the present processing, the corresponding optimum initial volume of 211 for the highest measured Jc was 40%. Further comparison between the weighted Jc and the true flux pinning force (Fp) also showed a maximum pinning force for an initial 211 addition of 40%. Although, the weighted Jc starts to decrease with an initial 211 volume of above 40%, the pinning efficiency at higher magnetic fields (2-4T) of the superconducting Y123 matrix was actually improved with an increasing 211 addition to at least 50%. Though an increasing addition of 211 was effective in producing efficient flux pinning sites in the Y123 matrix, percolation paths in the Y123 matrix became limited for supercurrent flow. Hence, a measured 211 volume corresponding to 80% 211 was shown to have the best possible critical current density. Furthermore, crack opening and crack spacing of the superficial cracks were found to decrease with an increasing 211 addition and with a decreasing 211 interparticle spacing. The penetration and surface length of each of these superficial cracks were hence reduced, which led to better electrical connectivity in the Y123 matrix. In addition, the effect of additives such as platinum and cerium oxide and their effect on the defect microstructure was quantitatively determined. Average twin spacing observed experimentally, suggested that the twin boundary energy (gammasb{tw}) was 28.9mJ/msp2 normally, while it decreased to 11.35mJ/msp2 for the 0.5wt% PtOsb2 doping and 23.6 mJ/msp2 for the case of 1 wt% CeOsb2 addition. The resultant twin morphology was also found to be substantially finer with PtOsb2 doping. Twin boundary energies were independently determined from twin shape analysis. Closer observation of the twins around a 211/Y123 interface showed a {1/ Rsp2} functional dependence of the local twin spacing at the 211/Y123 interface. The present study has also led to the identification of certain novel twin structures that have been shown to he efficient flux pinning sites. A study of this structure and its relationship with 211 particle shape, dispersion and proximity to its neighbors and its consequent effect on flux pinning was shown.

The AAE14 gene encodes the Arabidopsis o-succinylbenzoyl-CoA ligase that is essential for phylloquinone synthesis and photosystem-I function.

PubMed

Kim, Hyun Uk; van Oostende, Chloë; Basset, Gilles J C; Browse, John

2008-04-01

Phylloquinone is the one-electron carrier at the A(1) site of photosystem I, and is essential for photosynthesis. Arabidopsis mutants deficient in early steps of phylloquinone synthesis do not become autotrophic and are seedling lethals, even when grown on sucrose-supplemented media. Here, we identify acyl-activating enzyme 14 (AAE14, At1g30520) as the o-succinylbenzoyl-coenzyme A (OSB-CoA) ligase acting in phylloquinone synthesis. Three aae14 mutant alleles, identified by reverse genetics, were found to be seedling lethal, to contain no detectable phylloquinone (< 0.1 pmol mg(-1) fresh weight) compared with 10 pmol mg(-1) fresh weight in wild-type leaves, and to accumulate OSB. AAE14 was able to restore menaquinone biosynthesis when expressed in an Escherichia coli mutant disrupted in the menE gene that encodes the bacterial OSB-CoA ligase. Weak expression of an AAE14 transgene in mutant plants (controlled by the uninduced XVE promoter) resulted in chlorotic, slow-growing plants that accumulated an average of 4.7 pmol mg(-1) fresh weight of phylloquinone. Inducing the XVE promoter in these plants, or expressing an AAE14 transgene under the control of the CaMV 35S promoter, led to full complementation of the mutant phenotype. aae14-mutant plants were also able to synthesize phylloquinone when provided with 1,4-dihydroxy-2-naphthoate, an intermediate in phylloquinone synthesis downstream of the OSB-CoA ligase reaction. Expression of an AAE14:GFP reporter construct indicated that the protein accumulated in discrete foci within the chloroplasts. This and other evidence suggests that the enzymes of phylloquinone synthesis from isochorismate may form a complex in the chloroplast stroma to facilitate the efficient channeling of intermediates through the pathway.

Modular use of human body models of varying levels of complexity: Validation of head kinematics.

PubMed

Decker, William; Koya, Bharath; Davis, Matthew L; Gayzik, F Scott

2017-05-29

The significant computational resources required to execute detailed human body finite-element models has motivated the development of faster running, simplified models (e.g., GHBMC M50-OS). Previous studies have demonstrated the ability to modularly incorporate the validated GHBMC M50-O brain model into the simplified model (GHBMC M50-OS+B), which allows for localized analysis of the brain in a fraction of the computation time required for the detailed model. The objective of this study is to validate the head and neck kinematics of the GHBMC M50-O and M50-OS (detailed and simplified versions of the same model) against human volunteer test data in frontal and lateral loading. Furthermore, the effect of modular insertion of the detailed brain model into the M50-OS is quantified. Data from the Navy Biodynamics Laboratory (NBDL) human volunteer studies, including a 15g frontal, 8g frontal, and 7g lateral impact, were reconstructed and simulated using LS-DYNA. A five-point restraint system was used for all simulations, and initial positions of the models were matched with volunteer data using settling and positioning techniques. Both the frontal and lateral simulations were run with the M50-O, M50-OS, and M50-OS+B with active musculature for a total of nine runs. Normalized run times for the various models used in this study were 8.4 min/ms for the M50-O, 0.26 min/ms for the M50-OS, and 0.97 min/ms for the M50-OS+B, a 32- and 9-fold reduction in run time, respectively. Corridors were reanalyzed for head and T1 kinematics from the NBDL studies. Qualitative evaluation of head rotational accelerations and linear resultant acceleration, as well as linear resultant T1 acceleration, showed reasonable results between all models and the experimental data. Objective evaluation of the results for head center of gravity (CG) accelerations was completed via ISO TS 18571, and indicated scores of 0.673 (M50-O), 0.638 (M50-OS), and 0.656 (M50-OS+B) for the 15g frontal impact. Scores at lower g levels yielded similar results, 0.667 (M50-O), 0.675 (M50-OS), and 0.710 (M50-OS+B) for the 8g frontal impact. The 7g lateral simulations also compared fairly with an average ISO score of 0.565 for the M50-O, 0.634 for the M50-OS, and 0.606 for the M50-OS+B. The three HBMs experienced similar head and neck motion in the frontal simulations, but the M50-O predicted significantly greater head rotation in the lateral simulation. The greatest departure from the detailed occupant models were noted in lateral flexion, potentially indicating the need for further study. Precise modeling of the belt system however was limited by available data. A sensitivity study of these parameters in the frontal condition showed that belt slack and muscle activation have a modest effect on the ISO score. The reduction in computation time of the M50-OS+B reduces the burden of high computational requirements when handling detailed HBMs. Future work will focus on harmonizing the lateral head response of the models and studying localized injury criteria within the brain from the M50-O and M50-OS+B.

Design for low-cost gas metal arc weld-based aluminum 3-D printing

NASA Astrophysics Data System (ADS)

Haselhuhn, Amberlee S.

Additive manufacturing, commonly known as 3-D printing, has the potential to change the state of manufacturing across the globe. Parts are made, or printed, layer by layer using only the materials required to form the part, resulting in much less waste than traditional manufacturing methods. Additive manufacturing has been implemented in a wide variety of industries including aerospace, medical, consumer products, and fashion, using metals, ceramics, polymers, composites, and even organic tissues. However, traditional 3-D printing technologies, particularly those used to print metals, can be prohibitively expensive for small enterprises and the average consumer. A low-cost open-source metal 3-D printer has been developed based upon gas metal arc weld (GMAW) technology. Using this technology, substrate release mechanisms have been developed, allowing the user to remove a printed metal part from a metal substrate by hand. The mechanical and microstructural properties of commercially available weld alloys were characterized and used to guide alloy development in 4000 series aluminum-silicon alloys. Wedge casting experiments were performed to screen magnesium, strontium, and titanium boride alloying additions in hypoeutectic aluminum-silicon alloys for their properties and the ease with which they could be printed. Finally, the top performing alloys, which were approximately 11.6% Si modified with strontium and titanium boride were cast, extruded, and drawn into wire. These wires were printed and the mechanical and microstructural properties were compared with those of commercially available alloys. This work resulted in an easier-to-print aluminum-silicon-strontium alloy that exhibited lower porosity, equivalent yield and tensile strengths, yet nearly twice the ductility compared to commercial alloys.

Metal-Rich Transition Metal Diborides as Electrocatalysts for Hydrogen Evolution Reactions in a Wide Range of pH

DOE PAGES

Sitler, Steven J.; Raja, Krishnan S.; Charit, Indrajit

2016-09-23

Solid solutions of HfB 2-ZrB 2 mixtures were prepared by high-energy ball milling of diboride and additive powders followed by spark plasma sintering (SPS). A mixture of stoichiometric 1:1 HfB 2-ZrB 2 borides was the base composition to which Hf, Zr, Ta, LaB 6 or Gd 2O 3 was added. Hf, Zr and Ta were added in order to bring the boron-to-metal ratio down to 1.86, rendering the boride as MeB 1.86. In the case of LaB 6 and Gd 2O 3, 1.8 mol% was added. Electroanalytical behavior of hydrogen evolution reactions was evaluated in 1 M H 2SO 4more » and 1 M NaOH solutions. The LaB 6 additive material showed Tafel slopes of 125 and 90 mV/decade in acidic and alkaline solutions respectively. The Hf and Zr rich samples showed Tafel slopes of about 120 mV/decade in both electrolytes. The over potentials of hydrogen evolution reactions (at 10 mA/cm 2) in the alkaline solution were about 100 mV lower than those in acidic solution. The metal-rich diborides and addition of LaB 6 showed better hydrogen evolution reaction (HER) activities than the base 1:1 HfB 2-ZrB 2 stoichiometric diboride solid solution. Furthermore, the higher activity of metal-rich borides could be attributed to the increased electron population at the d-orbitals of the metal shown by band structure modeling calculations using the Density Functional Theory approach.« less

Thermal properties of zirconium diboride -- transition metal boride solid solutions

NASA Astrophysics Data System (ADS)

McClane, Devon Lee

This research focuses on the thermal properties of zirconium diboride (ZrB2) based ceramics. The overall goal was to improve the understanding of how different transition metal (TM) additives influence thermal transport in ZrB2. To achieve this, ZrB2 with 0.5 wt% carbon, and 3 mol% of individual transition metal borides, was densified by hot-press sintering. The transition metals that were investigated were: Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, and Re. The room temperature thermal diffusivities of the compositions ranged from 0.331 cm2/s for nominally pure ZrB2 to 0.105 cm2/s for (Zr,Cr)B2 and converged around 0.155cm2/s at higher temperatures for all compositions. Thermal conductivities were calculated from the diffusivities, using temperature-dependent values for density and heat capacity. The electron contribution to thermal conductivity was calculated from measured electrical resistivity according to the Wiedemann-Franz law. The phonon contribution to thermal conductivity was calculated by subtracting the electron contribution from the total thermal conductivity. Rietveld refinement of x-ray diffraction data was used to determine the lattice parameters of the compositions. The decrease in thermal conductivity for individual additives correlated directly to the metallic radius of the additive. Additional strain appeared to exist for additives when the stable TM boride for that metal had different crystal symmetries than ZrB2. This research provided insight into how additives and impurities affect thermal transport in ZrB2. The research potentially offers a basis for future modeling of thermal conductivity in ultra-high temperature ceramics based on the correlation between metallic radius and the decrease in thermal conductivity.

Processing, Microstructure, and Properties of Engineered Diboride Structures

NASA Astrophysics Data System (ADS)

Wittmaier, Connor Charles

The mechanical properties and processing parameters of boride ceramics in foam and laminate architectures were evaluated. The ceramic reticulated foam was produced through a polymer substrate replication technique and the hardness and compressive strength were tested. The laminate structure was tested to evaluate the flexure strength and work of fracture as a function of temperature. The foam architecture was produced using a TiB2 slurry coating on a polyurethane reticulated foam preform. Foams sintered to 2150°C displayed an average grain size of 8.9 +/- 7.3 microm, and a hardness of 17.3 +/- 2.4 GPa. Crush testing foams were sintered at 1975°C, and displayed a specific strength of 208 +/- 63 kPa with an overall porosity of 97%. For these specimens, it is likely that microcracking lowered the hardness, but the overall strength was controlled by the bulk density. The laminate structures were fabricated using alternating layers of ZrB 2 and C-10 vol% ZrB2. The structures were fabricated through the shaping of ceramic loaded thermoplastic polymers that underwent burnout and hot pressing cycles. These specimens had strong phase ZrB2 layers that were about 150 mum thick alternating with weak phase layers that were about 20 mum thick. Specimens exhibited a maximum flexure strength of 311 +/- 10 MPa at 1600°C, and an increased work of fracture compared to conventional ZrB2 ceramics. The maximum fraction of inelastic work of fracture occurred at room temperature, and decreased as temperature increased. This was reflected in the length of the crack path through the specimen. Deflected cracks travelled through the center of the C-ZrB2 layers in the material in Mode II fracture.

Exploring the additivity of binaural and monaural masking release.

PubMed

Hall, Joseph W; Buss, Emily; Grose, John H

2011-04-01

Experiment 1 examined comodulation masking release (CMR) for a 700-Hz tonal signal under conditions of N(o)S(o) (noise and signal interaurally in phase) and N(o)S(π) (noise in phase, signal out of phase) stimulation. The baseline stimulus for CMR was either a single 24-Hz wide narrowband noise centered on the signal frequency [on-signal band (OSB)] or the OSB plus, a set of flanking noise bands having random envelopes. Masking noise was either gated or continuous. The CMR, defined with respect to either the OSB or the random noise baseline, was smaller for N(o)S(π) than N(o)S(o) stimulation, particularly when the masker was continuous. Experiment 2 examined whether the same pattern of results would be obtained for a 2000-Hz signal frequency; the number of flanking bands was also manipulated (two versus eight). Results again showed smaller CMR for N(o)S(π) than N(o)S(o) stimulation for both continuous and gated masking noise. The CMR was larger with eight than with two flanking bands, and this difference was greater for N(o)S(o) than N(o)S(π). The results of this study are compatible with serial mechanisms of binaural and monaural masking release, but they indicate that the combined masking release (binaural masking-level difference and CMR) falls short of being additive.

Subminiature eddy current transducers for studying boride coatings

NASA Astrophysics Data System (ADS)

Dmitriev, S. F.; Ishkov, A. V.; Malikov, V. N.; Sagalakov, A. M.

2016-07-01

Strengthening of parts and units of machines, increased reliability and longer service life is an important task of modern mechanical engineering. The main objects of study in the work were selected steel 65G and 50HGA, wear-resistant boride coatings ternary system Fe-B-Fe n B which were investigated by scanning electron microscopy and eddy-current nondestructive methods.

Friction and wear of radiofrequency-sputtered borides, silicides, and carbides

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1978-01-01

The friction and wear properties of several refractory compound coatings were examined. These compounds were applied to 440 C bearing steel surfaces by radiofrequency (RF) sputtering. The refractory compounds were the titanium and molybdenum borides, the titanium and molybdenum silicides, and the titanium, molybdenum, and boron carbides. Friction testing was done with a pin-on-disk wear apparatus at loads from 0.1 to 5.0 newtons. Generally, the best wear properties were obtained when the coatings were bias sputtered onto 440 C disks that had been preoxidized. Adherence was improved because of the better bonding of the coatings to the iron oxide formed during preoxidation. As a class the carbides provided wear protection to the highest loads. Titanium boride coatings provided low friction and good wear properties to moderate loads.

Specific features of thermal and magnetic properties of Yb B50 at low temperatures

NASA Astrophysics Data System (ADS)

Novikov, V. V.; Zhemoedov, N. A.; Matovnikov, A. V.; Mitroshenkov, N. V.; Popova, E. A.; Tolstosheev, A. K.; Malkin, B. Z.; Bud'ko, S. L.

2018-05-01

Heat capacity, thermal expansion, and magnetization of ytterbium boride Yb B50 were studied at temperatures 0.6-300 K, 5-300 K, and 2-300 K, respectively. We revealed two smooth peaks at about 4.0 and 60 K in the temperature dependence of the heat capacity. A comparison with the heat capacity of the diamagnetic isostructural boride Lu B50 shows that these anomalies can be attributed to excitations in the ytterbium sublattice (Schottky anomalies). A scheme for splitting of the ground F 7 /2 2 multiplet of Y b3 + ions in the crystal field is proposed. Reliability of the proposed crystal-field energies of the Y b3 + ions is confirmed by the analysis of temperature dependencies of magnetic susceptibility and magnetization in applied magnetic fields up to 55 kOe. A clear anisotropy of the thermal expansion and a negative expansion within a wide temperature range (40-185 K) were observed. Assuming that this anomaly of the thermal expansion in higher borides is caused by the specific thermal evolution of a crystal lattice observed earlier, in particular, in Lu B50 , and the interaction of rare-earth ions with lattice strains, we have determined phenomenological Grüneisen parameters which characterize effects due to thermal transitions of Y b3 + ions between the ground and excited states. A phase transition of Yb B50 to any magnetically ordered state was not observed down to the lowest temperatures of experiments.

Physical and technological principles of designing layer-gradient multicomponent surfaces by combining the methods of ion-diffusion saturation and magnetron- and vacuum-arc deposition

NASA Astrophysics Data System (ADS)

Savostikov, V. M.; Potekaev, A. I.; Tabachenko, A. N.

2011-12-01

Using a technological system proposed by the authors, a combined process is developed for formation of stratified-gradient surface layers and multicomponent coatings. It is implemented under the conditions of a combined serial-parallel operation of a hot-cathode gas plasma generator and a duomagnetron with two targets and two electric-arc evaporators. The extended functional potential is ensured by using advanced multi-element and multi-phase cathode targets made of borides, carbides, silicides, and sulfides of metals produced by the SHS-process followed by their immediate compaction. The variations in composition, structure, and physicomechanical properties in the cross-section of the stratified-gradient surface layers and coating is provided by a predetermined alternating replacement of the sputtered cathode targets of the plasma sources, the plasma flow intensity ratios, and variation in the particle energy incident on the substrate, which is determined by the accelerating voltage on the substrate.

Posterior brain in fetuses with open spina bifida at 11 to 13 weeks.

PubMed

Lachmann, Robert; Chaoui, Rabih; Moratalla, Jose; Picciarelli, Gemma; Nicolaides, Kypros H

2011-01-01

To measure the changes in the posterior fossa in first-trimester fetuses with open spina bifida (OSB). The brain stem diameter and brain stem to occipital bone (BSOB) diameter were measured in stored images of the mid-sagittal view of the fetal face at 11(+0) to 13(+6) weeks from 30 fetuses with OSB and 1000 normal controls. In the control group, the brain stem and BSOB diameter increased significantly with crown-rump length (CRL) and the brain stem to BSOB ratio decreased. In the spina bifida group, the brain stem diameter was above the 95th percentile of the control group in 29 (96.7%) cases, the BSOB diameter was below the 5th percentile in 26 (86.7%) and the brain stem to BSOB ratio was above the 95th percentile in all cases. At 11 to 13 weeks the majority of fetuses with OSB have measurable abnormalities in the posterior brain.

Mode decomposition and Lagrangian structures of the flow dynamics in orbitally shaken bioreactors

NASA Astrophysics Data System (ADS)

Weheliye, Weheliye Hashi; Cagney, Neil; Rodriguez, Gregorio; Micheletti, Martina; Ducci, Andrea

2018-03-01

In this study, two mode decomposition techniques were applied and compared to assess the flow dynamics in an orbital shaken bioreactor (OSB) of cylindrical geometry and flat bottom: proper orthogonal decomposition and dynamic mode decomposition. Particle Image Velocimetry (PIV) experiments were carried out for different operating conditions including fluid height, h, and shaker rotational speed, N. A detailed flow analysis is provided for conditions when the fluid and vessel motions are in-phase (Fr = 0.23) and out-of-phase (Fr = 0.47). PIV measurements in vertical and horizontal planes were combined to reconstruct low order models of the full 3D flow and to determine its Finite-Time Lyapunov Exponent (FTLE) within OSBs. The combined results from the mode decomposition and the FTLE fields provide a useful insight into the flow dynamics and Lagrangian coherent structures in OSBs and offer a valuable tool to optimise bioprocess design in terms of mixing and cell suspension.

Airborne concentrations of methylene diphenyl diisocyanate (MDI) in North American wood mills during the manufacturing of oriented strand board (OSB).

PubMed

Karoly, William J; Flatley, John J; Stevenson, Ralph D; Bowers, John D

2004-12-01

Air monitoring data were collected from industrial hygiene surveys over an 8-year period in oriented strand board (OSB) mills. Personal samples were taken to evaluate potential employee exposures to MDI. Area samples were taken to determine the effectiveness of control measures used in the mills to prevent fugitive emissions of wood dust, MDI, and MDI-coated wood dust from the OSB manufacturing process. Personal sampling results (578 samples covering 11 different job categories) ranged from 0.0002-0.524 mg/m3, with a GM = 0.001 and GSD = 3.71. Area sampling results (1657 samples covering 14 stationary locations in the mills) ranged from 0.0002-2.5 mg/m3, with a GM = 0.004 and GSD = 5.52. The statistical range of the data suggests high variability. While exposures to MDI above the established limits (0.051 mg/m3, 8-hour time-weighted average, 0.2 mg/m3, ceiling) can and do occur when engineering controls are not maintained and/or proper work practices and personal protective equipment are not followed/used for certain high exposure potential tasks, the data indicate that over 97% of the personal and 92% of the area sampling results are less than 0.051 mg/m3. Wipe testing was performed to determine the presence of removable, unreacted diisocyanates (NCO functional groups)from various surfaces. Positive results were found in about 13% of the wipe tests on surfaces confined to the blender, forming line, and hopper deck process areas.

Updated results of bladder-sparing trimodality approach for invasive bladder cancer.

PubMed

Zapatero, Almudena; Martin de Vidales, Carmen; Arellano, Ramón; Bocardo, Gloria; Pérez, Mar; Ríos, Patricia

2010-01-01

To update long-term results with selective organ preservation in invasive bladder cancer using aggressive transurethral resection of bladder tumor (TURBT) and radiochemotherapy (RCT) and to identify treatment factors that may predict overall survival (OS). Between 1990 and 2007, a total of 74 patients with T2-T4 bladder cancer were enrolled in 2 sequential bladder-sparing protocols including aggressive TURB and RCT. From 1990 to 1999, 41 patients were included in protocol no. 1 (P1) that consisted of three cycles of neoadjuvant methotrexate, cisplatin, and vinblastine (MCV) chemotherapy prior to re-evaluation and followed by radiotherapy (RT) 60 Gy in complete responders. Between 2000 and 2007, 33 patients were entered in protocol no. 2 (P2) that consisted of concurrent RCT 64, 8 Gy with weekly cisplatin. In case of invasive residual tumor or recurrence, salvage cystectomy was recommended. Primary endpoints were OS, overall survival with bladder preservation (OSB), and late toxicity. The mean follow-up for the whole series was 54 months (range 9-156), 69 months for patients in P1 and 36 months for patients in P2. The actuarial 5-year OS and OSB for all series were 72% and 60%, respectively. Distant metastases were diagnosed in 11 (15%) patients. Grade 3 late genitourinary (GU) and intestinal (GI) complications were 5% and 1.3%, respectively. There were no significant differences in the incidence of superficial recurrences (P = 0.080), muscle-invasive relapses (P = 0.722), distant metastasis (P = 0.744), grade >/=2 late complications (P = 0.217 for GU and P = 0.400 for GI), and death among the 2 protocols (P value for OS = 0.643; P value for OSB = 0.532). These data confirm that trimodality therapy with bladder preservation represents a real alternative to radical cystectomy in selected patients, resulting in an acceptable rate of the long-term survivors retaining functional bladders. Copyright 2010 Elsevier Inc. All rights reserved.

Impact of stereotactic 11-g vacuum-assisted breast biopsy on cost of diagnosis in Austria.

PubMed

Gruber, R; Walter, E; Helbich, T H

2011-01-01

To determine the frequency with which stereotactic 11-g vacuum-assisted breast biopsy (11-g SVAB) obviates an open surgical biopsy (OSB), to compare the costs of these two biopsy methods, and to estimate the potential cost savings attributable to 11-g SVAB in the diagnosis of suspicious breast lesions in patients in Austria. We retrospectively reviewed 318 consecutive breast lesions of BI-RADS categories IV and V (microcalcifications n=166; masses n=152) on which 11-g SVAB and OSB were performed. Cost savings were calculated using nationally allowed flat rates and patient charges. Costs were measured from a hospital and a socioeconomic perspective. Common clinical scenarios and sensitivity analyses assessed the extent of achievable cost savings. 11-g SVAB obviated the need for an OSB in 93 (29%) of 318 women. Overall cost savings per 11-g SVAB over OSB were € 242 per case from a hospital perspective, and € 422 per case from a socioeconomic perspective. The use of 11-g SVAB decreased the cost of diagnosis by 7% from a hospital perspective, and by 10% from a socioeconomic perspective. In Austria, annual national savings of over 5 million Euro could be realized with the use of 11-g SVAB for the diagnosis of suspicious breast lesions. Although savings per case are modest, the national health care system realizes significant cost reduction as women benefit from a faster and less invasive approach to diagnosis. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

Optimum strata boundaries and sample sizes in health surveys using auxiliary variables

PubMed Central

2018-01-01

Using convenient stratification criteria such as geographical regions or other natural conditions like age, gender, etc., is not beneficial in order to maximize the precision of the estimates of variables of interest. Thus, one has to look for an efficient stratification design to divide the whole population into homogeneous strata that achieves higher precision in the estimation. In this paper, a procedure for determining Optimum Stratum Boundaries (OSB) and Optimum Sample Sizes (OSS) for each stratum of a variable of interest in health surveys is developed. The determination of OSB and OSS based on the study variable is not feasible in practice since the study variable is not available prior to the survey. Since many variables in health surveys are generally skewed, the proposed technique considers the readily-available auxiliary variables to determine the OSB and OSS. This stratification problem is formulated into a Mathematical Programming Problem (MPP) that seeks minimization of the variance of the estimated population parameter under Neyman allocation. It is then solved for the OSB by using a dynamic programming (DP) technique. A numerical example with a real data set of a population, aiming to estimate the Haemoglobin content in women in a national Iron Deficiency Anaemia survey, is presented to illustrate the procedure developed in this paper. Upon comparisons with other methods available in literature, results reveal that the proposed approach yields a substantial gain in efficiency over the other methods. A simulation study also reveals similar results. PMID:29621265

Optimum strata boundaries and sample sizes in health surveys using auxiliary variables.

PubMed

Reddy, Karuna Garan; Khan, Mohammad G M; Khan, Sabiha

2018-01-01

Using convenient stratification criteria such as geographical regions or other natural conditions like age, gender, etc., is not beneficial in order to maximize the precision of the estimates of variables of interest. Thus, one has to look for an efficient stratification design to divide the whole population into homogeneous strata that achieves higher precision in the estimation. In this paper, a procedure for determining Optimum Stratum Boundaries (OSB) and Optimum Sample Sizes (OSS) for each stratum of a variable of interest in health surveys is developed. The determination of OSB and OSS based on the study variable is not feasible in practice since the study variable is not available prior to the survey. Since many variables in health surveys are generally skewed, the proposed technique considers the readily-available auxiliary variables to determine the OSB and OSS. This stratification problem is formulated into a Mathematical Programming Problem (MPP) that seeks minimization of the variance of the estimated population parameter under Neyman allocation. It is then solved for the OSB by using a dynamic programming (DP) technique. A numerical example with a real data set of a population, aiming to estimate the Haemoglobin content in women in a national Iron Deficiency Anaemia survey, is presented to illustrate the procedure developed in this paper. Upon comparisons with other methods available in literature, results reveal that the proposed approach yields a substantial gain in efficiency over the other methods. A simulation study also reveals similar results.

Characterization of an Additive Manufactured TiAl Alloy-Steel Joint Produced by Electron Beam Welding.

PubMed

Basile, Gloria; Baudana, Giorgio; Marchese, Giulio; Lorusso, Massimo; Lombardi, Mariangela; Ugues, Daniele; Fino, Paolo; Biamino, Sara

2018-01-17

In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti₃Al followed by Al₃NiTi₂ and AlNi₂Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached.

Correlation between structural stability of LiBH4 and cation electronegativity in metal borides: an experimental insight for catalyst design.

PubMed

Cai, Weitong; Yang, Yuanzheng; Tao, Pingjun; Ouyang, Liuzhang; Wang, Hui

2018-04-03

Nanosized metal borides MBx (M = Mg, Ti, Fe, Si) are found to play an important role in enhancing the hydrogen storage performance of LiBH4 in this work. The hydrogen storage behavior and mechanism of these modified systems are investigated through TPD-MS, XRD, FTIR and SEM characterization methods. By introducing these metal borides into LiBH4 through ball milling, the systems display three dehydrogenation stages disclosing their similarity and distinction. The 1st stage starts at 190 °C, the 2nd stage ranges from 280 °C to 400 °C and the 3rd stage ends at 550 °C with a peak at round 440 °C similar to that of pristine LiBH4. Distinguishing features exist at the 2nd stage revealing the effectiveness of MBx in an order of MgB2 < TiB2 < FeB < SiB4. Significantly, reversibility up to 9.7 wt% is achieved from LiBH4 with assistance of SiB4. The catalytic effect of MBx is influenced by the Pauling electronegativity of M in MBx and the interfacial contact characteristic between LiBH4 and MBx. The larger electronegativity leads to an enhanced catalytic effect and consequently lower temperature at the major stage. In contrast to the components in the solid state, the molten LiBH4 promotes a catalytic effect due to a superior interfacial contact. These results provide an insight into designing high-performance catalysts applied to LiBH4 as a hydrogen storage material.

Multifunctional Ceramic Nanostructured Coatings

DTIC Science & Technology

2010-12-01

silicon carbide composites // J. Europ. Cer. Soc. − 2004. − Vol. 24. − P. 2169−2179. 22. Yu. P. Udalov, E. E. Valova, S. S. Ordanian. Fabrication and...by the titanium and tungsten borides and carbides . The analysis was done using the X-ray and electron-optical methods. This information expands our...coating compositions should be based on limited solubility materials. Such systems include carbides , nitrides, borides and silicides based on

Dynamics of β-cell turnover: evidence for β-cell turnover and regeneration from sources of β-cells other than β-cell replication in the HIP rat

PubMed Central

Manesso, Erica; Toffolo, Gianna M.; Saisho, Yoshifumi; Butler, Alexandra E.; Matveyenko, Aleksey V.; Cobelli, Claudio; Butler, Peter C.

2009-01-01

Type 2 diabetes is characterized by hyperglycemia, a deficit in β-cells, increased β-cell apoptosis, and islet amyloid derived from islet amyloid polypeptide (IAPP). These characteristics are recapitulated in the human IAPP transgenic (HIP) rat. We developed a mathematical model to quantify β-cell turnover and applied it to nondiabetic wild type (WT) vs. HIP rats from age 2 days to 10 mo to establish 1) whether β-cell formation is derived exclusively from β-cell replication, or whether other sources of β-cells (OSB) are present, and 2) to what extent, if any, there is attempted β-cell regeneration in the HIP rat and if this is through β-cell replication or OSB. We conclude that formation and maintenance of adult β-cells depends largely (∼80%) on formation of β-cells independent from β-cell duplication. Moreover, this source adaptively increases in the HIP rat, implying attempted β-cell regeneration that substantially slows loss of β-cell mass. PMID:19470833

Dynamics of beta-cell turnover: evidence for beta-cell turnover and regeneration from sources of beta-cells other than beta-cell replication in the HIP rat.

PubMed

Manesso, Erica; Toffolo, Gianna M; Saisho, Yoshifumi; Butler, Alexandra E; Matveyenko, Aleksey V; Cobelli, Claudio; Butler, Peter C

2009-08-01

Type 2 diabetes is characterized by hyperglycemia, a deficit in beta-cells, increased beta-cell apoptosis, and islet amyloid derived from islet amyloid polypeptide (IAPP). These characteristics are recapitulated in the human IAPP transgenic (HIP) rat. We developed a mathematical model to quantify beta-cell turnover and applied it to nondiabetic wild type (WT) vs. HIP rats from age 2 days to 10 mo to establish 1) whether beta-cell formation is derived exclusively from beta-cell replication, or whether other sources of beta-cells (OSB) are present, and 2) to what extent, if any, there is attempted beta-cell regeneration in the HIP rat and if this is through beta-cell replication or OSB. We conclude that formation and maintenance of adult beta-cells depends largely ( approximately 80%) on formation of beta-cells independent from beta-cell duplication. Moreover, this source adaptively increases in the HIP rat, implying attempted beta-cell regeneration that substantially slows loss of beta-cell mass.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpenter, Daniel; Westover, Tyler; Howe, Daniel

Here, we report here on an experimental study to produce refinery-ready fuel blendstocks via catalytic hydrodeoxygenation (upgrading) of pyrolysis oil using several biomass feedstocks and various blends. Blends were tested along with the pure materials to determine the effect of blending on product yields and qualities. Within experimental error, oil yields from fast pyrolysis and upgrading are shown to be linear functions of the blend components. Switchgrass exhibited lower fast pyrolysis and upgrading yields than the woody samples, which included clean pine, oriented strand board (OSB), and a mix of pinon and juniper (PJ). The notable exception was PJ, formore » which the poor upgrading yield of 18% was likely associated with the very high viscosity of the PJ fast pyrolysis oil (947 cp). The highest fast pyrolysis yield (54% dry basis) was obtained from clean pine, while the highest upgrading yield (50%) was obtained from a blend of 80% clean pine and 20% OSB (CP 8OSB 2). For switchgrass, reducing the fast pyrolysis temperature to 450 degrees C resulted in a significant increase to the pyrolysis oil yield and reduced hydrogen consumption during hydrotreating, but did not directly affect the hydrotreating oil yield. The water content of fast pyrolysis oils was also observed to increase linearly with the summed content of potassium and sodium, ranging from 21% for clean pine to 37% for switchgrass. Multiple linear regression models demonstrate that fast pyrolysis is strongly dependent upon the contents lignin and volatile matter as well as the sum of potassium and sodium.« less

Low-cost industrially available molybdenum boride and carbide as "platinum-like" catalysts for the hydrogen evolution reaction in biphasic liquid systems.

PubMed

Scanlon, Micheál D; Bian, Xiaojun; Vrubel, Heron; Amstutz, Véronique; Schenk, Kurt; Hu, Xile; Liu, BaoHong; Girault, Hubert H

2013-02-28

Rarely reported low-cost molybdenum boride and carbide microparticles, both of which are available in abundant quantities due to their widespread use in industry, adsorb at aqueous acid-1,2-dichloroethane interfaces and efficiently catalyse the hydrogen evolution reaction in the presence of the organic electron donor - decamethylferrocene. Kinetic studies monitoring biphasic reactions by UV/vis spectroscopy, and further evidence provided by gas chromatography, highlight (a) their superior rates of catalysis relative to other industrially significant transition metal carbides and silicides, as well as a main group refractory compound, and (b) their highly comparable rates of catalysis to Pt microparticles of similar dimensions. Insight into the catalytic processes occurring for each adsorbed microparticle was obtained by voltammetry at the liquid-liquid interface.

Determination of Oriented Strandboard properties from a three-dimensional density distribution using the finite element method

NASA Astrophysics Data System (ADS)

Tackie, Alan Derek Nii

Computer modeling of Oriented Strand Board (OSB) properties has gained widespread attention with numerous models created to better understand OBS behavior. Recent models allow researchers to observe multiple variables such as changes in moisture content, density and resin effects on panel performance. Thickness-swell variation influences panel durability and often has adverse effects on a structural panel's bending stiffness. The prediction of out-of-plane swell under changing moisture conditions was, therefore, the essence for developing a model in this research. The finite element model accounted for both vertical and horizontal density variations, the three-dimensional (3D) density variation of the board. The density variation, resulting from manufacturing processes, affects the uniformity of thickness-swell in OSB and is often exacerbated by continuous sorption of moisture that leads to potentially damaging internal stresses in the panel. The overall thickness-swell (the cumulative swell from non-uniform horizontal density profile, panel swell from free water, and spring-back from panel compression) was addressed through the finite element model in this research. The pursued goals in this study were, first and foremost, the development of a robust and comprehensive finite element model which integrated several component studies to investigate the effects of moisture variation on the out-of-plane thickness-swell of OSB panels, and second, the extension of the developed model to predict panel stiffness. It is hoped that this paper will encourage researchers to adopt the 3D density distribution approach as a viable approach to analyzing the physical and mechanical properties of OSB.

Thermodynamical and thermoelectric properties of boron doped YPd{sub 3} and YRh{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dwivedi, Shalini; Sharma, Yamini, E-mail: sharma.yamini62@gmail.com; Sharma, Ramesh

2016-05-23

The structural, electronic, thermal, and optical properties of borides of cubic non-magnetic YX{sub 3} (X=Rh, Pd) compounds and their borides which crystallize in the AuCu{sub 3} structure have been studied using the density functional theory (DFT). The flat bands in the vicinity of E{sub F} which are associated with superconductivity appear in YPd{sub 3} and YRh{sub 3} band structures. However, the B s-states enhance the flat band only in YRh{sub 3}B. The optical properties clearly show that boron insertion modifies the absorption and transmittance. The YX{sub 3} alloys and their borides exhibit valuable changes in the thermopower and ZT. Itmore » is observed that the properties of the Y-X intermetallics change significantly for the Y-Rh and Y-Pd alloys and the presence of single boron atom modifies the properties to a great extent.« less

Low temperature synthesis of transition metal oxides containing surfactant ions

NASA Astrophysics Data System (ADS)

Janauer, Gerald Gilbert

1998-11-01

Recently there has been much interest in reacting vanadium oxides hydrothermally with cationic surfactants to form novel layered compounds. A series of new transition metal oxides, however, has also been formed at or near room temperature in open containers. Synthesis, characterization, and proposed mechanisms of formation are the focus of this work. Low temperature reactions of vanadium pentoxide and ammonium transition metallates with long chain amine surfactants, such as dodecyltrimethylammonium bromide yielded interesting new products many of which are layered phases. DTAsb4\\ Hsb2Vsb{10}Osb{28}. 8Hsb2O, a layered highly crystalline phase, is the first such phase for which a single crystal X-ray structure has been determined. The unit cell for this material was found to be triclinic with space group P1-, cell parameters a=9.8945(3)A, b=11.5962(1)A, c=21.9238(2)A, alpha=95.153(2)sp°,\\ beta=93.778(1)sp°, and gamma=101.360(1)sp°. Additionally, a novel tungsten, a molybdenum and a dichromate phase will be discussed. Both the tungsten and the dichromate materials were indexed from their powder diffraction patterns yielding monoclinic unit cells. The tungsten material was found to have a=50.56(4)A, b=54.41(4)A, c=13.12(1)A, and beta=99.21sp°. The dichromate compound was determined to have a=26.757(5)A, b=10.458(2)A, c=14.829(3)A and beta=98.01(1)sp°. Interlayer spacings for the lamellar dichromate and molybdenum phases were d001 = 28.7 A, and d001 = 22.9 A. The synthesis, characterization, composition, and structure of these transition metal oxide-surfactant materials will be discussed.

Transport of polar and non-polar volatile compounds in polystyrene foam and oriented strand board

NASA Astrophysics Data System (ADS)

Yuan, Huali; Little, John C.; Hodgson, Alfred T.

Transport of hexanal and styrene in polystyrene foam (PSF) and oriented strand board (OSB) was characterized. A microbalance was used to measure sorption/desorption kinetics and equilibrium data. While styrene transport in PSF can be described by Fickian diffusion with a symmetrical and reversible sorption/desorption process, hexanal transport in both PSF and OSB exhibited significant hysteresis, with desorption being much slower than sorption. A porous media diffusion model that assumes instantaneous local equilibrium governed by a nonlinear Freundlich isotherm was found to explain the hysteresis in hexanal transport. A new nonlinear sorption and porous diffusion emissions model was, therefore, developed and partially validated using independent chamber data. The results were also compared to the more conventional linear Fickian-diffusion emissions model. While the linear emissions model predicts styrene emissions from PSF with reasonable accuracy, it substantially underestimates the rate of hexanal emissions from OSB. Although further research and more rigorous validation is needed, the new nonlinear emissions model holds promise for predicting emissions of polar VOCs such as hexanal from porous building materials.

Cytotoxicity and genotoxicity in human lung epithelial A549 cells caused by airborne volatile organic compounds emitted from pine wood and oriented strand boards.

PubMed

Gminski, Richard; Tang, Tao; Mersch-Sundermann, Volker

2010-06-16

Due to the massive reduction of air-change rates in modern, energy-saving houses and dwellings, the contribution of volatile organic compound (VOCs) emissions from wood-based materials to indoor air quality has become increasingly important. To evaluate toxicity of VOC mixtures typically emitted from pine wood and oriented strand boards (OSB) and their main constituents (selected terpenes and aldehydes), cytotoxicity and genotoxicity were investigated in human A549 lung cells. To facilitate exposure directly via gas phase, a 250 L emission chamber was combined with a Vitrocell exposure system. VOC exposure concentrations were measured by GC/MSD. Biological effects were determined after an exposure time of 1h by measuring cytotoxicity (erythrosine B staining) and genotoxicity (comet assay). Neither cytotoxic nor genotoxic effects were observed for VOC mixtures emitted from pine wood or OSB at loading factors of approximately 13 m(2)/m(3) (worst case conditions) of the panels (with maximum VOC levels of about 80 mg/m(3)) in comparison to clean air. While alpha-pinene and Delta(3)-carene did not induce toxic effects even at exposure concentrations of up to 1800 mg/m(3) and 600 mg/m(3), respectively, hexanal showed a cytotoxic effect at 2000 mg/m(3). The alpha,beta-unsaturated aldehydes 2-heptenal and 2-octenal caused genotoxic effects in concentrations exceeding 100mg/m(3) and 40 mg/m(3), respectively. In conclusion, high concentrations of VOCs and VOC mixtures emitted from pine wood and OSB did not lead to adverse effects in A549 human lung cells even at concentrations 10(2) to 10(5)-fold higher than those found in normal indoor air. Attention must be paid to mutagenic and possibly carcinogenic alpha,beta-unsaturated aldehydes. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Surface chemistry relevant to material processing for semiconductor devices

NASA Astrophysics Data System (ADS)

Okada, Lynne Aiko

Metal-oxide-semiconductor (MOS) structures are the core of many modern integrated circuit (IC) devices. Each material utilized in the different regions of the device has its own unique chemistry. Silicon is the base semiconductor material used in the majority of these devices. With IC device complexity increasing and device dimensions decreasing, understanding material interactions and processing becomes increasingly critical. Hsb2 desorption is the rate-limiting step in silicon growth using silane under low temperature conditions. Activation energies for Hsb2 desorption measured during Si chemical vapor deposition (CVD) versus single-crystal studies are found to be significantly lower. It has been proposed that defect sites on the silicon surface could explain the observed differences. Isothermal Hsb2 desorption studies using laser induced thermal desorption (LITD) techniques have addressed this issue. The growth of low temperature oxides is another relevant issue for fabrication of IC devices. Recent studies using 1,4-disilabutane (DSB) (SiHsb3CHsb2CHsb2SiHsb3) at 100sp°C in ambient Osb2 displayed the successful low temperature growth of silicon dioxide (SiOsb2). However, these studies provided no information about the deposition mechanism. We performed LITD and Fourier transform infrared (FTIR) studies on single-crystal and porous silicon surfaces to examine the adsorption, decomposition, and desorption processes to determine the deposition mechanism. Titanium nitride (TiN) diffusion barriers are necessary in modern metallization structures. Controlled deposition using titanium tetrachloride (TiClsb4) and ammonia (NHsb3) has been demonstrated using atomic layered processing (ALP) techniques. We intended to study the sequential deposition method by monitoring the surface intermediates using LITD techniques. However, formation of a Cl impurity source, ammonium chloride (NHsb4sp+Clsp-), was observed, thereby, limiting our ability for effective studies. Tetrakis(dimethylamino)titanium (Tilbrack N\\{CHsb3\\}sb2rbracksb4) (TDMAT) is another precursor used in the CVD deposition of TiN films in IC devices. Thermal decomposition studies have demonstrated deviations from conformal deposition. Successful conformal deposition may be affected by readsorption of the reaction product, dimethylamine (HNlbrack CHsb3rbracksb2). Detailed studies were performed using LITD techniques in order to understand the adsorption and desorption kinetics of TDMAT and dimethylamine to gain insights about the conformal deposition of TiN.

Composition and structure of surfaces by time-of-flight scattering and recoiling spectrometry (TOF-SARS)

NASA Astrophysics Data System (ADS)

Ahn, Jeongheon

1997-10-01

Time-of-flight scattering and recoiling spectrometry (TOF-SARS) was applied to characterize surface structures in order to understand the chemical and physical phenomena on various surfaces. The combination of TOF-SARS, LEED, and classical ion trajectory simulations has allowed characterization of the elemental composition in the outermost atomic layers, surface symmetry, and possible reconstruction or relaxation. The composition and structure of the CdS\\{0001\\}-(1 x 1) and CdS\\{000bar1\\}-(1 x 1) surfaces were investigated. The termination layer of each surface was determined by grazing incidence TOF-SARS. Both (1 x 1) surfaces are bulk-terminated without any reconstruction or relaxation detected by TOF-SARS. Each surface has two domains which are rotated by 60sp° from each other and there exist steps on both surfaces. The CdS\\{0001\\}-(1 x 1) surface is stabilized by O and H covering half a monolayer which are structurally ordered on the surface, while the O and H on the CdS\\{000bar1\\}-(1 x 1) stabilize the surface without ordering. The study of GaN\\{000bar1\\}-(1 x 1) shows the bulk-termination of the surface with no detectable reconstruction or relaxation. The surface is terminated in a N layer with Ga in the 2sp{nd}-layer. H atoms are bound to the outermost N atoms with a coverage of ˜3/4 monolayer and protrude outward from the surface. The surface termination, composition and structure of the Alsb2Osb3 (sapphire) were examined. The surface relaxation was studied quantitatively using classical ion trajectory simulations along with TOF-SARS. The surface undergoes 1sp{st}{-}2sp{nd}-layer relaxation as large as 0.5 A from the bulk value resulting in near coplanarity of Al and O atoms. The reconstruction of the Ni\\{100\\}-(2 x 2)-C surface was studied by TOF-SARS. The surface contained 80% of the (2 x 2)p4g phase and 20% of the unreconstructed (2 x 2) phase. The displacement of Ni atoms was determined by comparing the experimental and simulated results.

The friction and wear properties of sputtered hard refractory compounds

NASA Technical Reports Server (NTRS)

Brainard, W. A.

1978-01-01

Several refractory silicide, boride, and carbide coatings were examined. The coatings were applied to type 440C steel surfaces by radio-frequency sputtering. The friction and wear properties of the coatings were found to be related to stoichiometry and impurity content of the bulk coating as well as the degree of interfacial adherence between coating and substrate. Bulk coating stoichiometry could to a large extent be controlled by the application of a negative bias voltage during deposition. Adherence was promoted by the formation of an oxidized layer at the interface. Deliberate preoxidizing of the 440C produced enhanced adherence for many compounds which are related to the formation of a mixed oxide transition region.

Anomalous stress response of ultrahard WB n compounds

DOE PAGES

Li, Quan; Zhou, Dan; Zheng, Weitao; ...

2015-10-29

Boron-rich tungsten borides are premier prototypes of a new class of ultrahard compounds. Here, we show by first-principles calculations that their stress-strain relations display surprisingly diverse and anomalous behavior under a variety of loading conditions. Most remarkable is the dramatically changing bonding configurations and deformation modes with rising boron concentration in WB n (n=2, 3, 4), resulting in significantly different stress responses and unexpected indentation strength variations. This novel phenomenon stems from the peculiar structural arrangements in tungsten borides driven by boron’s ability to form unusually versatile bonding states. Our results elucidate the intriguing deformation mechanisms that define a distinctmore » type of ultrahard material. Here, these new insights underscore the need to explore unconventional structure-property relations in a broad range of transition-metal light-element compounds.« less

Unexpected Neighborhood Sources of Food and Drink: Implications for Research and Community Health.

PubMed

Lucan, Sean C; Maroko, Andrew R; Seitchik, Jason L; Yoon, Dong Hum; Sperry, Luisa E; Schechter, Clyde B

2018-06-11

Studies of neighborhood food environments typically focus on select stores (especially supermarkets) and/or restaurants (especially fast-food outlets), make presumptions about healthfulness without assessing actual items for sale, and ignore other kinds of businesses offering foods/drinks. The current study assessed availability of select healthful and less-healthful foods/drinks from all storefront businesses in an urban environment and considered implications for food-environment research and community health. Cross-sectional assessment in 2013 of all storefront businesses (n=852) on all street segments (n=1,253) in 32 census tracts of the Bronx, New York. Investigators assessed for healthful items (produce, whole grains, nuts, water, milk) and less-healthful items (refined sweets, salty/fatty fare, sugar-added drinks, and alcohol), noting whether items were from food businesses (e.g., supermarkets and restaurants) or other storefront businesses (OSB, e.g., barber shops, gyms, hardware stores, laundromats). Data were analyzed in 2017. Half of all businesses offered food/drink items. More than one seventh of all street segments (more than one third in higher-poverty census tracts) had businesses selling food/drink. OSB accounted for almost one third of all businesses offering food/drink items (about one quarter of businesses offering any healthful items and more than two thirds of businesses offering only less-healthful options). Food environments include many businesses not primarily focused on selling foods/drinks. Studies that do not consider OSB may miss important food/drink sources, be incomplete and inaccurate, and potentially misguide interventions. OSB hold promise for improving food environments and community health by offering healthful items; some already do. Copyright © 2018 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Catalytic hydroprocessing of fast pyrolysis oils: Impact of biomass feedstock on process efficiency

DOE PAGES

Carpenter, Daniel; Westover, Tyler; Howe, Daniel; ...

2016-12-01

Here, we report here on an experimental study to produce refinery-ready fuel blendstocks via catalytic hydrodeoxygenation (upgrading) of pyrolysis oil using several biomass feedstocks and various blends. Blends were tested along with the pure materials to determine the effect of blending on product yields and qualities. Within experimental error, oil yields from fast pyrolysis and upgrading are shown to be linear functions of the blend components. Switchgrass exhibited lower fast pyrolysis and upgrading yields than the woody samples, which included clean pine, oriented strand board (OSB), and a mix of pinon and juniper (PJ). The notable exception was PJ, formore » which the poor upgrading yield of 18% was likely associated with the very high viscosity of the PJ fast pyrolysis oil (947 cp). The highest fast pyrolysis yield (54% dry basis) was obtained from clean pine, while the highest upgrading yield (50%) was obtained from a blend of 80% clean pine and 20% OSB (CP 8OSB 2). For switchgrass, reducing the fast pyrolysis temperature to 450 degrees C resulted in a significant increase to the pyrolysis oil yield and reduced hydrogen consumption during hydrotreating, but did not directly affect the hydrotreating oil yield. The water content of fast pyrolysis oils was also observed to increase linearly with the summed content of potassium and sodium, ranging from 21% for clean pine to 37% for switchgrass. Multiple linear regression models demonstrate that fast pyrolysis is strongly dependent upon the contents lignin and volatile matter as well as the sum of potassium and sodium.« less

Modelling the power deposition into a spherical tokamak fusion power plant

NASA Astrophysics Data System (ADS)

Windsor, C. G.; Morgan, J. G.; Buxton, P. F.; Costley, A. E.; Smith, G. D. W.; Sykes, A.

2017-03-01

Numerical studies have been made to improve the performance of the central column of a superconducting spherical tokamak fusion pilot plant. The assumed neutron shield includes concentric layers of tungsten carbide and water. The relative thickness of the water layers was varied and a minimum power deposition was found at about 17% of water. It was found advantageous to have an approximately 1.7 times thicker water layer next to the core and a similarly thinner layer next to the plasma. The use of tungsten boride instead of tungsten carbide was shown to make an improvement especially if placed close to the central superconducting core, the inner layer alone reducing the power deposition by 29%. Engineering features such as a central steel tie-bar, an insulating thermal vacuum gap, a wall gap next to the plasma and knowledge of the vertical energy distribution are essential to a successful design and their effects on the power deposition are shown in an appendix. The results have been fitted to model distributions and incorporated into the Tokamak Energy System Code, which can then give predictions of the power deposition as a function of other parameters such as the plasma major radius and the maximum magnetic field permitted on the superconductors.

Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

DOEpatents

Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

2003-09-23

Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

Ultra High Temperature Ceramics' Processing Routes and Microstructures Compared

NASA Technical Reports Server (NTRS)

Gusman, Michael; Stackpoole, Mairead; Johnson, Sylvia; Gasch, Matt; Lau, Kai-Hung; Sanjurjo, Angel

2009-01-01

Ultra High Temperature Ceramics (UHTCs), such as HfB2 and ZrB2 composites containing SiC, are known to have good thermal shock resistance and high thermal conductivity at elevated temperatures. These UHTCs have been proposed for a number of structural applications in hypersonic vehicles, nozzles, and sharp leading edges. NASA Ames is working on controlling UHTC properties (especially, mechanical properties, thermal conductivity, and oxidation resistance) through processing, composition, and microstructure. In addition to using traditional methods of combining additives to boride powders, we are preparing UHTCs using coat ing powders to produce both borides and additives. These coatings and additions to the powders are used to manipulate and control grain-boundary composition and second- and third-phase variations within the UHTCs. Controlling the composition of high temperature oxidation by-products is also an important consideration. The powders are consolidated by hot-pressing or field-assisted sintering (FAS). Comparisons of microstructures and hardness data will be presented.

The effect of melt refining upon inclusions in aluminum

NASA Astrophysics Data System (ADS)

Simensen, C. J.

1982-03-01

A series of aluminum melts has been refined with respect to inclusions by use of ALCOA 469, FILD, or SNIF. The content and size distribution of inclusions in the original-and the refined melts-have been measured by use of neutron activation (oxygen content), gas chromatography (carbide content), sedimentation analysis, and dissolution of metal in hydrochloric acid and subsequent analysis of oxides by means of a Coulter Counter. All the units tested have a beneficial effect and decrease the inclusion content, but the number of analyses are too few to make general conclusions. However, for melts cleaned by use of SNIF, it was found that oxides larger than 50 μm in cross section and borides larger than 20 μm in diameter were removed, while the smaller borides were agglomerated only. The effect of FILD and ALCOA 469 upon the melt tested was removal of borides larger than 5-10 μ m and oxides larger than 15μm in diameter, respectively.

Amorphous nickel boride membrane on a platinum-nickel alloy surface for enhanced oxygen reduction reaction.

PubMed

He, Daping; Zhang, Libo; He, Dongsheng; Zhou, Gang; Lin, Yue; Deng, Zhaoxiang; Hong, Xun; Wu, Yuen; Chen, Chen; Li, Yadong

2016-08-09

The low activity of the oxygen reduction reaction in polymer electrolyte membrane fuel cells is a major barrier for electrocatalysis, and hence needs to be optimized. Tuning the surface electronic structure of platinum-based bimetallic alloys, a promising oxygen reduction reaction catalyst, plays a key role in controlling its interaction with reactants, and thus affects the efficiency. Here we report that a dealloying process can be utilized to experimentally fabricate the interface between dealloyed platinum-nickel alloy and amorphous nickel boride membrane. The coating membrane works as an electron acceptor to tune the surface electronic structure of the platinum-nickel catalyst, and this composite catalyst composed of crystalline platinum-nickel covered by amorphous nickel boride achieves a 27-times enhancement in mass activity relative to commercial platinum/carbon at 0.9 V for the oxygen reduction reaction performance. Moreover, this interactional effect between a crystalline surface and amorphous membrane can be readily generalized to facilitate the 3-times higher catalytic activity of commercial platinum/carbon.

Influence of heat treatment on microstructure and hot crack susceptibility of laser-drilled turbine blades made from Rene 80

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osterle, W.; Krause, S.; Moelders, T.

2008-11-15

Turbine components from conventionally cast nickel-base alloy Rene 80 show different hot cracking susceptibilities depending on their heat treatment conditions leading to slightly different microstructures. Electron probe micro-analysis, focused ion beam technique and analytical transmission electron microscopy were applied to reveal and identify grain boundary precipitates and the {gamma}-{gamma}'-microstructure. The distribution of borides along grain boundaries was evaluated statistically by quantitative metallography. The following features could be correlated with an increase of cracking susceptibility: i) Increasing grain size, ii) increasing fraction of grain boundaries with densely spaced borides, iii) lack of secondary {gamma}'-particles in matrix channels between the coarse cuboidalmore » {gamma}'-precipitates. The latter feature seems to be responsible for linking-up of cracked grain boundary precipitates which occurred as an additional cracking mechanism after one heat treatment, whereas decohesion at the boride-matrix-interface in the heat affected zone of laser-drilled holes was observed for both heat treatments.« less

Ash Tree Leaf Litter (Fraxinus excelsior L.) Breakdown in Two Different Biotopes and Streams

NASA Astrophysics Data System (ADS)

Fleituch, Tadeusz; Leichtfried, Maria

2004-11-01

Coarse (0.5 mm) and fine (0.1 mm) mesh size bag methodology was used for comparing the breakdown of ash tree leaves (Fraxinus excelsior L.) in two biotopes (dry - terrestrial and wet - overflown stream zones) in two low order streams (the Oberer Seebach (OSB), Lower Austria and the Brzezowka stream (BRZ), Beskidy Mountains, southern Poland). In total, 96 bags were exposed in autumn 2000. Ash-free dry mass (AFDM) ranged in dry zones of both streams from 94-62% (OSB) and 85-53% (BRZ) respectively. The decomposition process was faster in wet zones: 96-33% (OSB) and 56-11% (B) during the study period. Significant differences in ash breakdown and its chemical content between studied streams were found. Total organic carbon (TOC) and total nitrogen content (TN) of AFDM of litter showed increased differences with experiment duration between zones and between two bag types for both streams. The strongest increase of TOC and TN content (100% on average initial content) for bag types, zones, and streams was observed in the first two weeks of the experiment. These results confirm the importance of chemical compounds for microbiological processes (biofilms) in different ecosystem biotopes. (

Magnetic properties and magnetic hardening mechansim of Pt-Co-B alloys

NASA Technical Reports Server (NTRS)

Qiu, Ning; Flanagan, F.; Wittig, James E.

1994-01-01

The intrinsic coercivity is found to be maximized in the Pt42Co45B13 ternary alloy which is undercooled and rapidly solidified (quenched using a 70 m/s wheel speed after undercooling), and then annealed (800 C for 2400 min). The same alloy, processed at slower cooling rates and annealed in the same way, has a much larger scale microstructure and a much lower resulting magnetic coercivity. The microstructure which would optimize the coercitvity of this coercivity of this ternary alloy is a completely ordered L1(sub zero) Pt-Co matrix with a submicron magnetic single-domion Co-boride precipitate. The L1(sub zero) phase is highly anistropic magnetically while the Co-boride precipate is somewhat less so. Annealing treatments designed to produced single-domain Co-boride precipitates enhance the coercivity. This suggests that the refined microstructures is responsible for the high coercivities found in the rapidly solidified and annealed alloy. The magnetic domain wall thickness for a Co-boride precipitate is determined from both experimental observation and theoretical calculation in order to evaluate its influence on the coercivity of the alloy. The effects of the pinning of domain walls and the barrier to the nucleation of reverse domains on the coercivity are discussed. Both microstrucutral analysis and theoretical calculation indicate that the high coercivities in the Pt42Co45B13 alloy are due to the difficult nucleation of reverse magnetic domains.

Simple, Green, and High-Yield Production of Boron-Based Nanostructures with Diverse Morphologies by Dissolution and Recrystallization of Layered Magnesium Diboride Crystals in Water.

PubMed

Gunda, Harini; Das, Saroj Kumar; Jasuja, Kabeer

2018-04-05

Layered metal diborides that contain metal atoms sandwiched between boron honeycomb planes offer a rich opportunity to access graphenic forms of boron. We recently demonstrated that magnesium diboride (MgB 2 ) could be exfoliated by ultrasonication in water to yield boron-based nanosheets. However, knowledge of the fate of metal boride crystals in aqueous phases is still in its incipient stages. This work presents our preliminary findings on the discovery that MgB 2 crystals can undergo dissolution in water under ambient conditions to result in precursors (prenucleation clusters) that, upon aging, undergo nonclassical crystallization preferentially growing in lateral directions by two-dimensional (2D) oriented attachment. We show that this recrystallization can be utilized as an avenue to obtain a high yield (≈92 %) of boron-based nanostructures, including nanodots, nanograins, nanoflakes, and nanosheets. These nanostructures comprise boron honeycomb planes chemically modified with hydride and oxy functional groups, which results in an overall negative charge on their surfaces. This ability of MgB 2 crystals to yield prenucleation clusters that can self-seed to form nanostructures comprising chemically modified boron honeycomb planes presents a new facet to the physicochemical interaction of MgB 2 with water. These findings also open newer avenues to obtain boron-based nanostructures with tunable morphologies by varying the chemical milieu during recrystallization. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Influence of Nano-Scale Silicon Nitride Additions on the Physical and Magnetic Properties of Iron Sheathed Magnesium Boride Wires

NASA Astrophysics Data System (ADS)

Zhu, W.; Cave, J.

2006-03-01

The enhancement of flux line pinning in magnesium boride wires is a critical issue for their future applications in devices and machines. It is well known that small size dopants can significantly influence the current densities of these materials. Here, the influence of nanometric (<30nm) silicon nitride on physical properties and current density is presented. The iron-sheathed powder in tube wires were prepared using pure magnesium and boron powders with silicon nitride additions. The wires were rolled flat and treated at up to 900 degrees C in flowing argon. SEM and XRD were used to identify phases and microstructures. Magnetization critical currents, up to several 100 of thousands A/cm2, at various temperatures and fields (5K - 20K and up to 3 tesla) show that there are competing mechanisms from chemical and flux pinning effects.

Grain Refinement and Texture Mitigation in Low Boron Containing TiAl-Alloys

NASA Astrophysics Data System (ADS)

Hecht, Ulrike; Witusiewicz, Victor T.

2017-12-01

Controlling the grain size and texture of lamellar TiAl-alloys is essential for well-balanced creep and fatigue properties. Excellent refinement and texture mitigation are achieved in aluminum lean alloys by low boron additions of 0.2 at.%. This amount is sufficient to promote in situ formation of ultrafine borides during the last stages of body centered cubic (BCC) solidification. The borides subsequently serve as nucleation sites for hexagonal close packed (HCP) during the BCC-HCP phase transformation. Bridgman solidification experiments with alloy Ti-43Al-8Nb-0.2C-0.2B were performed under a different growth velocity, i.e., cooling rate, to evaluate the HCP grain size distribution and texture. For slow-to-moderate cooling rates, about 65% of HCP grains are randomly oriented, despite the pronounced texture of the parent BCC phase resulting from directional solidification. For high cooling rates, obtained by quenching, texture mitigation is less pronounced. Only 28% of the HCP grains are randomly oriented, the majority being crystallographic variants of the Burgers orientation relationship.

Fine structure of the K X-ray absorption spectra of titanium in some hydrides, borides, and silicides (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vainshtein, �. E.; Zhurakovskii, E. A.

1959-08-01

X-ray spectral analyses confirmed the hypothesis on the metal-like state of hydrogen in tithnium hydrides. Experiments with titunium borides and silicides indicate the special character and degree of the 3d--level participation in the metallic'' bond between the atoms of various complexes. The structure of metalloid elements becomes more complicated with an increase in the specific number of boron and silicon atoms and the bond between the atoms tends to become covalent. (R.V.J.)

History of ``NANO''-Scale VERY EARLY Solid-State (and Liquid-State) Physics/Chemistry/Metallurgy/ Ceramics; Interstitial-Alloys Carbides/Nitrides/Borides/...Powders and Cermets, Rock Shocks, ...

NASA Astrophysics Data System (ADS)

Maiden, Colin; Siegel, Edward

History of ``NANO'': Siegel-Matsubara-Vest-Gregson[Mtls. Sci. and Eng. 8, 6, 323(`71); Physica Status Solidi (a)11,45(`72)] VERY EARLY carbides/nitrides/borides powders/cermets solid-state physics/chemistry/metallurgy/ ceramics FIRST-EVER EXPERIMENTAL NANO-physics/chemistry[1968 ->Physica Status Solidi (a)11,45(`72); and EARLY NANO-``physics''/NANO-``chemistry'' THEORY(after: Kubo(`62)-Matsubara(`60s-`70s)-Fulde (`65) [ref.: Sugano[Microcluster-Physics, Springer('82 `98)

Effect of environmental conditions on the flexural properties of wood I-beams and lumber

Treesearch

Gwo-Huang Chen; R.C. Tang; E.W. Price

1989-01-01

Flexural properties as affected by environmental conditions were evaluated for full-sized wood composite I-beams webbed with oriented strand board (OSB), randomly oriented flakeboard (RF) and 3-ply Structural I plywood (PLY). Solid-sawn southern pine 2 by 10's, ordinarily used in light-frame building construction, were also tested for comparative purposes....

Complete titanium substitution by boron in a tetragonal prism: exploring the complex boride series Ti(3-x)Ru(5-y)Ir(y)B(2+x) (0 ≤ x ≤ 1 and 1 < y < 3) by experiment and theory.

PubMed

Fokwa, Boniface P T; Hermus, Martin

2011-04-18

Polycrystalline samples and single crystals of four members of the new complex boride series Ti(3-x)Ru(5-y)Ir(y)B(2+x) (0 ≤ x ≤ 1 and 1 < y < 3) were synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. The new silvery phases were structurally characterized by powder and single-crystal X-ray diffraction as well as energy- and wavelength-dispersive X-ray spectroscopy analyses. They crystallize with the tetragonal Ti(3)Co(5)B(2) structure type in space group P4/mbm (No. 127). Tetragonal prisms of Ru/Ir atoms are filled with titanium in the boron-poorest phase (Ti(3)Ru(2.9)Ir(2.1)B(2)). Gradual substitution of titanium by boron then results in the successive filling of this site by a Ti/B mixture en route to the complete boron occupation, leading to the boron-richest phase (Ti(2)Ru(2.8)Ir(2.2)B(3)). Furthermore, both ruthenium and iridium share two sites in these structures, but a clear Ru/Ir site preference is found. First-principles density functional theory calculations (Vienna ab initio simulation package) on appropriate structural models (using a supercell approach) have provided more evidence on the stability of the boron-richest and -poorest phases, and the calculated lattice parameters corroborate very well with the experimentally found ones. Linear muffin-tin orbital atomic sphere approximation calculations further supported these findings through crystal orbital Hamilton population bonding analyses, which also show that the Ru/Ir-B and Ru/Ir-Ti heteroatomic interactions are mainly responsible for the structural stability of these compounds. Furthermore, some stable and unstable phases of this complex series could be predicted using the rigid-band model. According to the density of states analyses, all phases should be metallic conductors, as was expected from these metal-rich borides.

Microstructure of Vacuum-Brazed Joints of Super-Ni/NiCr Laminated Composite Using Nickel-Based Amorphous Filler Metal

NASA Astrophysics Data System (ADS)

Ma, Qunshuang; Li, Yajiang; Wu, Na; Wang, Juan

2013-06-01

Vacuum brazing of super-Ni/NiCr laminated composite and Cr18-Ni8 stainless steel was carried out using Ni-Cr-Si-B amorphous filler metal at 1060, 1080, and 1100 °C, respectively. Microstructure and phase constitution were investigated by means of optical and scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction, and micro-hardness tester. When brazed at 1060-1080 °C, the brazed region can be divided into two distinct zones: isothermally solidified zone (ISZ) consisting of γ-Ni solid solution and athermally solidified zone (ASZ) consisting of Cr-rich borides. Micro-hardness of the Cr-rich borides formed in the ASZ was as high as 809 HV50 g. ASZ decreased with increase of the brazing temperature. Isothermal solidification occurred sufficiently at 1100 °C and an excellent joint composed of γ-Ni solid solution formed. The segregation of boron from ISZ to residual liquid phase is the reason of Cr-rich borides formed in ASZ. The formation of secondary precipitates in diffusion-affected zone is mainly controlled by diffusion of B.

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

The first certified Zero Energy Ready Home in Georgia was honored in the Custom Builder category of the 2014 Housing Innovation Awards. The 2,811-ft2, two-story custom home has 2x6 advanced framed walls filled with R-20 of open-cell spray foam, plus an R-6.6 insulated coated OSB sheathing. Also included is electronic monitoring equipment that tracks the PV, solar thermal water heater, ERV, mini-split heat pump with three indoor heads, solar water heater, and LED and CFL lighting.

Electrically conductive containment vessel for molten aluminum

DOEpatents

Holcombe, C.E.; Scott, D.G.

1984-06-25

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal 10 borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Electrically conductive containment vessel for molten aluminum

DOEpatents

Holcombe, Cressie E.; Scott, Donald G.

1985-01-01

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Brazing Inconel 625 Using Two Ni/(Fe)-Based Amorphous Filler Foils

NASA Astrophysics Data System (ADS)

Chen, Wen-Shiang; Shiue, Ren-Kae

2012-07-01

For MBF-51 filler, the brazed joint consists of interfacial grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr-rich matrix. In contrast, the VZ-2106 brazed joint is composed of interfacial Nb6Ni16Si7 precipitates as well as grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr/Fe-rich matrix. The maximum tensile strength of 443 MPa is obtained from the MBF-51 brazed specimen. The tensile strengths of VZ-2106 brazed joints are approximately 300 MPa. Both amorphous filler foils demonstrate potential in brazing IN-625 substrate.

Mechanical, Electronic and Optical Properties of Two Phases of NbB4: First-Principles Calculations

NASA Astrophysics Data System (ADS)

Yang, Ruike; Ma, Shaowei; Wei, Qun; Zhang, Dongyun

2018-05-01

As transition metal borides have been successfully synthesised, the study of the combination of transition metal and boron is another effective way to investigate the properties of boride. We have predicted the novel phase Amm2-NbB4. Using the Cambridge Serial Total Energy Package (CASTEP) code, we further researched on the mechanical, electronic and optical properties of C2/c- and Amm2-NbB4. It is found that both the phases of NbB4 are dynamically and mechanically stable at 0 and 100 GPa. Their Vickers hardness values are both 34 GPa, which indicate that they are hard materials. The band gap of C2/c-NbB4 is 0.145 eV, which indicates that it is a semiconductor (or metalloid) at 0 GPa. For the Amm2-NbB4, the band structure without band gap indicates it is a metal at 0 GPa. The optical properties of these two structures are similar. At 0 eV, the real part of dielectric function is 28.8 for C2/c-NbB4, and the real part value for Amm2-NbB4 is 43. We hope our work will provide some help to the experimental work about the technology of the material.

2001 Australian Defence Force Reserves Survey Report

DTIC Science & Technology

2001-11-01

56 71 Attitudes Towards Reserves Activities Being Part of Member’s Social Life..... 56v i 2...for Social and Economic Modelling NEOC New Entry Officer Course OFFICER CDT Officer Cadet OP GOLD Operation Gold ORs Other Ranks (LS/CPL and below) OSB...Reserve members. An evaluation of the data was undertaken by the National Centre of Social and Economic Modelling (NATSEM) to establish the

Boron-Based Hydrogen Storage: Ternary Borides and Beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vajo, John J.

DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slowmore » rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.« less

On the transferability of electron density in binary vanadium borides VB, V3B4 and VB2.

PubMed

Terlan, Bürgehan; Akselrud, Lev; Baranov, Alexey I; Borrmann, Horst; Grin, Yuri

2015-12-01

Binary vanadium borides are suitable model systems for a systematic analysis of the transferability concept in intermetallic compounds due to chemical intergrowth in their crystal structures. In order to underline this structural relationship, topological properties of the electron density in VB, V3B4 and VB2 reconstructed from high-resolution single-crystal X-ray diffraction data as well as derived from quantum chemical calculations, are analysed in terms of Bader's Quantum Theory of Atoms in Molecules [Bader (1990). Atoms in Molecules: A Quantum Theory, 1st ed. Oxford: Clarendon Press]. The compounds VB, V3B4 and VB2 are characterized by a charge transfer from the metal to boron together with two predominant atomic interactions, the shared covalent B-B interactions and the polar covalent B-M interactions. The resembling features of the crystal structures are well reflected by the respective B-B interatomic distances as well as by ρ(r) values at the B-B bond critical points. The latter decrease with an increase in the corresponding interatomic distances. The B-B bonds show transferable electron density properties at bond critical points depending on the respective bond distances.

Boride Formation Induced by pcBN Tool Wear in Friction-Stir-Welded Stainless Steels

NASA Astrophysics Data System (ADS)

Park, Seung Hwan C.; Sato, Yutaka S.; Kokawa, Hiroyuki; Okamoto, Kazutaka; Hirano, Satoshi; Inagaki, Masahisa

2009-03-01

The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

A superconducting battery material: Lithium gold boride (LiAu3B)

NASA Astrophysics Data System (ADS)

Aydin, Sezgin; Şimşek, Mehmet

2018-04-01

The superconducting and potential cathode material properties of ternary boride of LiAu3B have been investigated by density functional first principles. The Li-concentration effects on the actual electronic and structural properties, namely the properties of LixAu9B3 (x = 0, 1, 2) sub-systems are studied. It is remarkably shown that the existence of Li-atoms has no considerable effect on the structural properties of Au-B skeleton in LiAu3B. Then, it can be offered as a potential cathode material for Li-ion batteries with the very small volume deviation of 0.42%, and the suitable average open circuit voltage of ∼1.30 V. Furthermore, the vibrational and superconducting properties such as electron-phonon coupling constant (λ) and critical temperature (Tc) of LiAu3B are studied. The calculated results suggest that LiAu3B should be a superconductor with Tc ∼5.8 K, also.

Menaquinone (vitamin K2) biosynthesis: overexpression, purification, and properties of o-succinylbenzoyl-coenzyme A synthetase from Escherichia coli.

PubMed Central

Kwon, O; Bhattacharyya, D K; Meganathan, R

1996-01-01

The coenzyme A (CoA)- and ATP-dependent conversion of o-succinylbenzoic acid [OSB; 4-(2'-carboxyphenyl)-4-oxobutyric acid], to o-succinylbenzoyl-CoA is carried out by the enzyme o-succinylbenzoyl-CoA synthetase. o-Succinylbenzoyl-CoA is a key intermediate in the biosynthesis of menaquinone (vitamin K2) in both gram-negative and gram-positive bacteria. The enzyme has been overexpressed and purified to homogeneity. The purified enzyme was found to have a native molecular mass of 185 kDa as determined by gel filtration column chromatography on Sephacryl S-200. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis established a subunit molecular mass of 49 kDa. Thus, the enzyme is a homotetramer. The enzyme showed a pH optimum of 7.5 to 8.0 and a temperature optimum of 30 to 40 degrees C. The Km values for OSB, ATP, and CoA were 16, 73.5, and 360 microM, respectively. Of the various metal ions tested, Mg2+ was found to be the most effective in stimulating the enzyme activity. Studies with substrate analogs showed that neither benzoic acid nor benzoylpropionic acid (succinylbenzene) is a substrate for the enzyme. Thus, it appears that both the benzoyl carboxyl group and the succinyl side chain are required for activation of the aliphatic carboxyl group. PMID:8955296

Wood biodegradation in laboratory-scale landfills.

PubMed

Wang, Xiaoming; Padgett, Jennifer M; De la Cruz, Florentino B; Barlaz, Morton A

2011-08-15

The objective of this research was to characterize the anaerobic biodegradability of major wood products in municipal waste by measuring methane yields, decay rates, the extent of carbohydrate decomposition, carbon storage, and leachate toxicity. Tests were conducted in triplicate 8 L reactors operated to obtain maximum yields. Measured methane yields for red oak, eucalyptus, spruce, radiata pine, plywood (PW), oriented strand board (OSB) from hardwood (HW) and softwood (SW), particleboard (PB) and medium-density fiberboard (MDF) were 32.5, 0, 7.5, 0.5, 6.3, 84.5, 0, 5.6, and 4.6 mL CH(4) dry g(-1), respectively. The red oak, a HW, exhibited greater decomposition than either SW (spruce and radiata), a trend that was also measured for the OSB-HW relative to OSB-SW. However, the eucalyptus (HW) exhibited toxicity. Thus, wood species have unique methane yields that should be considered in the development of national inventories of methane production and carbon storage. The current assumption of uniform biodegradability is not appropriate. The ammonia release from urea formaldehyde as present in PB and MDF could contribute to ammonia in landfill leachate. Using the extent of carbon conversion measured in this research, 0-19.9%, predicted methane production from a wood mixture using the Intergovernmental Panel for Climate Change waste model is only 7.9% of that predicted using the 50% carbon conversion default.

Prospective detection of open spina bifida at 11-13 weeks by assessing intracranial translucency and posterior brain.

PubMed

Chaoui, R; Benoit, B; Heling, K S; Kagan, K O; Pietzsch, V; Sarut Lopez, A; Tekesin, I; Karl, K

2011-12-01

We describe a case series of six fetuses with open spina bifida (OSB) from four different prenatal units, where the anomaly was detected at the routine 11-13-week ultrasound examination. Crown-rump length ranged from 49 to 78 mm. All cases were first suspected during nuchal translucency thickness measurement in the mid-sagittal plane of the face. OSB was lumbosacral in five fetuses and cervical in one. The intracranial translucency (IT) was obliterated in two cases, but some fluid was found in the other four cases. However, in all cases the typical landmarks of a normal posterior brain and normal IT were absent. In all six cases the ratio of brainstem diameter to brainstem-occipital bone distance was increased (≥ 1). This detection of an abnormal posterior brain led to a targeted examination and detection of the spinal lesion during the same examination in five cases, whereas in one suspicious case the patient was recalled at 17 weeks, when the abnormality was detected. Two fetuses had both multiple anomalies and trisomy 18. These prospective cases demonstrate the feasibility of using the standard mid-sagittal plane commonly used for NT measurement to assess the IT and the posterior brain and to determine the presence of OSB during NT screening. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

Preliminary investigation of zirconium boride ceramals for gas-turbine blade applications

NASA Technical Reports Server (NTRS)

Hoffman, Charles A

1953-01-01

Zirconium boride ZrB2 ceramals were investigated for possible gas-turbine-blade application. Included in the study were thermal shock evaluations of disks, preliminary turbine-blade operation, and observations of oxidation resistance. Thermal shock disks of the following three compositions were studied: (a) 97.5 percent ZrB2 plus 2.5 percent B by weight; (b) 92.5 percent ZrB2 plus 7.5 percent B by weight; and (c) 100 percent ZrB2. Thermal shock disks were quenched from temperatures of 1800 degrees, 2000 degrees, 2200 degrees, and 2400 degrees F. The life of turbine blades containing 93 percent ZrB2 plus 7 percent B by weight was determined in gas-turbine tests. The blades were run at approximately 1600 degrees F and 15,000 to 26,000 rpm. The thermal shock resistance of the 97.5 percent ZrB2 plus 2.5 percent boron ceramals compares favorably with that of TiC plus Co and TiC plus Ni ceramals. Oxidation of the disks during the thermal shock evaluation was slight for the comparatively short time (8.3 hr) up through 2000 degrees F. Oxidation of a specimen was severe, however, after 100 hours at 2000 degrees F. The turbine blade performance evaluation of the 93 percent ZrB2 plus 7 percent B composition was preliminary in scope ; no conclusions can be drawn.

The physical and mechanical metallurgy of advanced O+BCC titanium alloys

NASA Astrophysics Data System (ADS)

Cowen, Christopher John

This thesis comprises a systematic study of the microstructural evolution, phase transformation behavior, elevated-temperature creep behavior, room-temperature and elevated-temperature tensile behavior, and room-temperature fatigue behavior of advanced titanium-aluminum-niobium (Ti-Al-Nb) alloys with and without boron additions. The specific alloys studied were: Ti-5A1-45Nb (at%), Ti-15Al-33Nb (at%), Ti-15Al-33Nb-0.5B (at%), Ti-15Al-33Nb-5B (at%), Ti-21Al-29Nb (at%), Ti-22Al-26Nb (at%), and Ti-22Al-26Nb-5B (at%). The only alloy composition that had been previously studied before this thesis work began was Ti-22Al-26Nb (at%). Publication in peer-reviewed material science journals of the work performed in this thesis has made data available in the scientific literature that was previously non-existent. The knowledge gap for Ti-Al-Nb phase equilibria over the compositional range of Ti-23Al-27Nb (at%) to Ti-12Al-38Nb (at%) that existed before this work began was successfully filled. The addition of 5 at% boron to the Ti-15Al-33Nb alloy produced 5-9 volume percent boride phase needles within the microstructure. The chemical composition of the boride phase measured by electron microprobe was determined to be approximately B 2TiNb. The lattice parameters of the boride phase were simulated through density functional theory calculations by collaborators at the Air Force Research Laboratory based on the measured composition. Using the simulated lattice parameters, electron backscatter diffraction kikuchi patterns and selected area electron diffraction patterns obtained from the boride phase were successfully indexed according to the space group and site occupancies of the B27 orthorhombic crystal structure. This suggests that half the Ti (c) Wyckoff positions are occupied by Ti atoms and the other half are occupied by Nb atoms in the boride phase lattice. Creep deformation behavior is the main focus of this thesis and in particular understanding the dominant creep deformation mechanisms as a function of stress, temperature, and strain rate. Microstructure-creep relationships for Ti-Al-Nb-xB alloys were developed with the understanding gained. A rule-of-mixtures empirical model based on constituent phase volume fractions and strain rates was developed to predict the minimum creep rates of two-phase O+BCC microstructures. The most innovative results of this thesis were produced through the development of an in-situ creep testing methodology. The creep deformation evolution was chronicled in-situ during high temperature creep experiments, while creep displacement versus time data was simultaneously obtained. The in-situ experiments revealed that prior-BCC grain boundaries were the locus of damage accumulation during creep deformation. A methodology that allows in-situ observation of surface creep deformation as a function of creep displacement has yet to be presented in the literature.

DFT investigations of hydrogen storage materials

NASA Astrophysics Data System (ADS)

Wang, Gang

Hydrogen serves as a promising new energy source having no pollution and abundant on earth. However the most difficult problem of applying hydrogen is to store it effectively and safely, which is smartly resolved by attempting to keep hydrogen in some metal hydrides to reach a high hydrogen density in a safe way. There are several promising metal hydrides, the thermodynamic and chemical properties of which are to be investigated in this dissertation. Sodium alanate (NaAlH4) is one of the promising metal hydrides with high hydrogen storage capacity around 7.4 wt. % and relatively low decomposition temperature of around 100 °C with proper catalyst. Sodium hydride is a product of the decomposition of NaAlH4 that may affect the dynamics of NaAlH4. The two materials with oxygen contamination such as OH- may influence the kinetics of the dehydriding/rehydriding processes. Thus the solid solubility of OH - groups (NaOH) in NaAlH4 and NaH is studied theoretically by DFT calculations. Magnesium boride [Mg(BH4)2] is has higher hydrogen capacity about 14.9 wt. % and the decomposition temparture of around 250 °C. However one flaw restraining its application is that some polyboron compounds like MgB12H12 preventing from further release of hydrogen. Adding some transition metals that form magnesium transition metal ternary borohydride [MgaTMb(BH4)c] may simply the decomposition process to release hydrogen with ternary borides (MgaTMbBc). The search for the probable ternary borides and the corresponding pseudo phase diagrams as well as the decomposition thermodynamics are performed using DFT calculations and GCLP method to present some possible candidates.

In vitro dissolution of strontium titanate to estimate clearance rates in human lungs

NASA Astrophysics Data System (ADS)

Anderson, Jeri Lynn

At the In-Tank Precipitation facility (ITP) of the Savannah River Site, strontium and other radionuclides are removed from high-level radioactive waste and sent to the Defense Waste Processing Facility (DWPF). Strontium removal is accomplished by ion-exchange using monosodium titanate slurry which creates a form of strontium titanate with unknown solubility characteristics. In the case of accidental inhalation of a compound containing radioactive strontium, the ICRP, in Publication 66, recommends using default values for rates of absorption into body fluids at the lungs in the absence of reliable human or animal data. The default value depends on whether the absorption is considered to be fast, moderate, or slow (Type F, M, or S). Current dose assessment for an individual upon inadvertent exposure to airborne radioactive strontium assumes that all strontium compounds are Type F (soluble) or Type S (insoluble). Pure high-fired strontium titanate (SrTiOsb3) is considered Type S. The purpose of this project was to determine the solubility of strontium titanate in the form created at the ITP facility. An in vitro dissolution study was done with a precipitate simulant and with several types of strontium titanate and the results were compared. An in vivo study was also performed with high-fired SrTiOsb3 in rats. The data from both studies were used independently to assign the compounds to absorption type based on criteria specified in ICRP 71. Results of the in vitro studies showed that the DWPF simulant should be assigned to Type M and the strontium titanate should be assigned to Type S. It is possible the difference in the DWPF simulant is due to the other chemicals present. Results of the in vivo study verified that SrTiOsb3 should be assigned to Type S. Lung clearance data of SrTiOsb3 from rats showed that 85% cleared within the first 24 hours and the remaining 15% with a half-time of 130 days. The initial rapid clearance is attributed to deposition in airways as compared to the alveolar region.

Mechanism of the Intramolecular Claisen Condensation Reaction Catalyzed by MenB, a Crotonase Superfamily Member†

PubMed Central

Li, Huei-Jiun; Li, Xiaokai; Liu, Nina; Zhang, Huaning; Truglio, James J.; Mishra, Shambhavi; Kisker, Caroline; Garcia-Diaz, Miguel; Tonge, Peter J.

2014-01-01

MenB, the 1,4-dihydroxy-2-naphthoyl-CoA synthase from the bacterial menaquinone biosynthesis pathway, catalyzes an intramolecular Claisen condensation (Dieckmann reaction) in which the electrophile is an unactivated carboxylic acid. Mechanistic studies on this crotonase family member have been hindered by partial active site disorder in existing MenB X-ray structures. In the current work the 2.0 Å structure of O-succinylbenzoyl-aminoCoA (OSB-NCoA) bound to the MenB from Escherichia coli provides important insight into the catalytic mechanism by revealing the position of all active site residues. This has been accomplished by the use of a stable analogue of the O-succinylbenzoyl-CoA (OSB-CoA) substrate in which the CoA thiol has been replaced by an amine. The resulting OSB-NCoA is stable and the X-ray structure of this molecule bound to MenB reveals the structure of the enzyme-substrate complex poised for carbon-carbon bond formation. The structural data support a mechanism in which two conserved active site Tyr residues, Y97 and Y258, participate directly in the intramolecular transfer of the substrate α-proton to the benzylic carboxylate of the substrate, leading to protonation of the electrophile and formation of the required carbanion. Y97 and Y258 are also ideally positioned to function as the second oxyanion hole required for stabilization of the tetrahedral intermediate formed during carbon-carbon bond formation. In contrast, D163, which is structurally homologous to the acid-base catalyst E144 in crotonase, is not directly involved in carbanion formation and may instead play a structural role by stabilizing the loop that carries Y97. When similar studies were performed on the MenB from Mycobacterium tuberculosis, a twisted hexamer was unexpectedly observed, demonstrating the flexibility of the interfacial loops that are involved in the generation of the novel tertiary and quaternary structures found in the crotonase superfamily. This work reinforces the utility of using a stable substrate analogue as a mechanistic probe in which only one atom has been altered leading to a decrease in α-proton acidity. PMID:21830810

Mechanism of the intramolecular Claisen condensation reaction catalyzed by MenB, a crotonase superfamily member.

PubMed

Li, Huei-Jiun; Li, Xiaokai; Liu, Nina; Zhang, Huaning; Truglio, James J; Mishra, Shambhavi; Kisker, Caroline; Garcia-Diaz, Miguel; Tonge, Peter J

2011-11-08

MenB, the 1,4-dihydroxy-2-naphthoyl-CoA synthase from the bacterial menaquinone biosynthesis pathway, catalyzes an intramolecular Claisen condensation (Dieckmann reaction) in which the electrophile is an unactivated carboxylic acid. Mechanistic studies on this crotonase family member have been hindered by partial active site disorder in existing MenB X-ray structures. In the current work the 2.0 Å structure of O-succinylbenzoyl-aminoCoA (OSB-NCoA) bound to the MenB from Escherichia coli provides important insight into the catalytic mechanism by revealing the position of all active site residues. This has been accomplished by the use of a stable analogue of the O-succinylbenzoyl-CoA (OSB-CoA) substrate in which the CoA thiol has been replaced by an amine. The resulting OSB-NCoA is stable, and the X-ray structure of this molecule bound to MenB reveals the structure of the enzyme-substrate complex poised for carbon-carbon bond formation. The structural data support a mechanism in which two conserved active site Tyr residues, Y97 and Y258, participate directly in the intramolecular transfer of the substrate α-proton to the benzylic carboxylate of the substrate, leading to protonation of the electrophile and formation of the required carbanion. Y97 and Y258 are also ideally positioned to function as the second oxyanion hole required for stabilization of the tetrahedral intermediate formed during carbon-carbon bond formation. In contrast, D163, which is structurally homologous to the acid-base catalyst E144 in crotonase (enoyl-CoA hydratase), is not directly involved in carbanion formation and may instead play a structural role by stabilizing the loop that carries Y97. When similar studies were performed on the MenB from Mycobacterium tuberculosis, a twisted hexamer was unexpectedly observed, demonstrating the flexibility of the interfacial loops that are involved in the generation of the novel tertiary and quaternary structures found in the crotonase superfamily. This work reinforces the utility of using a stable substrate analogue as a mechanistic probe in which only one atom has been altered leading to a decrease in α-proton acidity.

Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Crx(Rh1-yRuy)7-xB3 (x=0.88-1; y=0-1) with Th7Fe3-type structure

NASA Astrophysics Data System (ADS)

Misse, Patrick R. N.; Mbarki, Mohammed; Fokwa, Boniface P. T.

2012-08-01

Powder samples and single crystals of the new complex boride series Crx(Rh1-yRuy)7-xB3 (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th7Fe3 structure type (space group P63mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region.

The future of naval ocean science research

NASA Astrophysics Data System (ADS)

Orcutt, John A.; Brink, Kenneth

The Ocean Studies Board (OSB) of the National Research Council reviewed the changing role of basic ocean science research in the Navy at a recent board meeting. The OSB was joined by Gerald Cann, assistant secretary of the Navy for research, development, and acquisition; Geoffrey Chesbrough, oceanographer of the Navy; Arthur Bisson, deputy assistant secretary of the Navy for antisubmarine warfare; Robert Winokur, technical director of the Office of the Oceanographer of the Navy; Bruce Robinson, director of the new science directorate at the Office of Naval Research (ONR); and Paul Gaffney, commanding officer of the Naval Research Laboratory (NRL). The past 2-3 years have brought great changes to the Navy's mission with the dissolution of the former Soviet Union and challenges presented by conflicts in newly independent states and developing nations. The new mission was recently enunciated in a white paper, “From the Sea: A New Direction for the Naval Service,” which is signed by the secretary of the Navy, the chief of naval operations, and the commandant of the Marine Corps. It departs from previous plans by proposing a heavier emphasis on amphibious operations and makes few statements about the traditional Navy mission of sea-lane control.

Binaural comodulation masking release: Effects of masker interaural correlation

PubMed Central

Hall, Joseph W.; Buss, Emily; Grose, John H.

2007-01-01

Binaural detection was examined for a signal presented in a narrow band of noise centered on the on-signal masking band (OSB) or in the presence of flanking noise bands that were random or comodulated with respect to the OSB. The noise had an interaural correlation of 1.0 (No), 0.99 or 0.95. In No noise, random flanking bands worsened Sπ detection and comodulated bands improved Sπ detection for some listeners but had no effect for other listeners. For the 0.99 or 0.95 interaural correlation conditions, random flanking bands were less detrimental to Sπ detection and comodulated flanking bands improved Sπ detection for all listeners. Analyses based on signal detection theory indicated that the improvement in Sπ thresholds obtained with comodulated bands was not compatible with an optimal combination of monaural and binaural cues or to across-frequency analyses of dynamic interaural phase differences. Two accounts consistent with the improvement in Sπ thresholds in comodulated noise were (1) envelope information carried by the flanking bands improves the weighting of binaural cues associated with the signal; (2) the auditory system is sensitive to across-frequency differences in ongoing interaural correlation. PMID:17225415

Structural, electronic and thermal properties of super hard ternary boride, WAlB

NASA Astrophysics Data System (ADS)

Rajpoot, Priyanka; Rastogi, Anugya; Verma, U. P.

2018-04-01

A first principle study of the structural, electronic and thermal properties of Tungsten Aluminum Boride (WAlB) using full-potential linearized augmented plane wave (FP-LAPW) in the frame work of density function theory (DFT) have been calculated. The calculated equilibrium structural parameters are in excellent agreement with available experimental results. The calculated electronic band structure reveals that WAlB is metallic in nature. The quasi-harmonic Debye model is applied to study of the temperature and pressure effect on volume, Debye temperature, thermal expansion coefficient and specific heat at constant volume and constant pressure. To the best of our knowledge theoretical investigation of these properties of WAlB is reported for the first time.

Infiltration processing of boron carbide-, boron-, and boride-reactive metal cermets

DOEpatents

Halverson, Danny C.; Landingham, Richard L.

1988-01-01

A chemical pretreatment method is used to produce boron carbide-, boron-, and boride-reactive metal composites by an infiltration process. The boron carbide or other starting constituents, in powder form, are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents. The chemically treated starting constituents are consolidated into a porous ceramic precursor which is then infiltrated by molten aluminum or other metal by heating to wetting conditions. Chemical treatment of the starting constituents allows infiltration to full density. The infiltrated precursor is further heat treated to produce a tailorable microstructure. The process at low cost produces composites with improved characteristics, including increased toughness, strength.

Low VOC drying of lumber and wood panel products. Progress report Number 9 [January 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, H.; Banerjee, S.; Conners, T.

1999-01-01

Results from a multi-year study show that a significant part of the extensive variability observed in oriented strand board (OSB) flake dryer emissions can be traced to physiological effects, and the rest can be attributed to handling and other factors. Low-headspace treatment of lumber was scaled up to the 50 kg level. The amount of turpentine collected was of the same magnitude as that released upon drying lumber. For the process to be economical, the wood must first be brought to about 95 C with steam, and then processed with RF. Attempts to remove VOCs from OSB through low-headspace bymore » placing a curtain over the wood failed because of leaks. A more rigid container will be required. RF-treatment does not alter the gas permeability of lumber.« less

Low VOC drying of lumber and wood panel products. Progress report Number 9

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, H.; Banerjee, S.; Conners, T.

1999-01-01

Results from a multi-year study show that a significant part of the extensive variability observed in oriented strand board (OSB) flake dryer emissions can be traced to physiological effects, and the rest can be attributed to handling and other factors. Low-headspace treatment of lumber was scaled up to the 50 kg level. The amount of turpentine collected was of the same magnitude as that released upon drying lumber. For the process to be economical, the wood must first be brought to about 95 C with steam, and then processed with RF. Attempts to remove VOCs from OSB through low-headspace bymore » placing a curtain over the wood failed because of leaks. A more rigid container will be required. RF-treatment does not alter the gas permeability of lumber.« less

High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

DTIC Science & Technology

2010-06-02

ceramics with silicide additives may be explained in the following ways: 1) metal oxide, for example Ta2O5, formed at oxidation of TaSi2, in the...practically monophase ones, possibly, the additives of corresponding metals in silicide powders were present in insignificant amounts. For...boride with zirconium silicide we prepared the mixtures with 20 vol. % of silicide , the latter being hot pressed in the temperature range of 1600

The Quantitative Significance of Nondestructive Evaluation of Graphite and Ceramic Materials.

DTIC Science & Technology

NONDESTRUCTIVE TESTING), (* GRAPHITE , (*BORIDES, NONDESTRUCTIVE TESTING), (*REFRACTORY MATERIALS, NONDESTRUCTIVE TESTING), DEFECTS(MATERIALS), TENSILE PROPERTIES, RADIOGRAPHY, ULTRASONIC PROPERTIES, DENSITY.

High-Temperature Syntheses of New, Thermally-Stable Chemical Compounds.

DTIC Science & Technology

SYNTHESIS(CHEMISTRY), HEAT RESISTANT PLASTICS, NITRILES, FLUORINE COMPOUNDS, COMPLEX COMPOUNDS, NITROGEN, SULFIDES, ORGANOMETALLIC COMPOUNDS, ORGANOBORANES, BORIDES, SPINEL, CARBIDES, NITRIDES, SILICIDES .

Gravel bar thermal variability and its potential consequences for CO2 evasion from Alpine coldwater streams

NASA Astrophysics Data System (ADS)

Boodoo, Kyle; Battin, Tom; Schelker, Jakob

2017-04-01

Gravel bars (GB) are ubiquitous in-stream structures with relatively large exposed surfaces, capable of absorbing heat and possibly acting as a heat source to the underlying hyporheic zone (HZ). The distinctive mixing of groundwater and surface water within their HZ largely determines its characteristic physical and biogeochemical properties, including temperature distribution. To study thermal variability within GBs and its possible consequences for CO2 evasion fluxes we analysed high frequency spatio-temporal data for a range of stream and atmospheric physical parameters including the vertical GB temperature, in an Alpine cold water stream (Oberer Seebach, Austria) over the course of a year. We found the vertical temperature profiles within the GB to vary seasonally and with discharge. We extended our study to 13 other gravel bars of varying physical characteristics within the surrounding Ybbs and Erlauf catchments, conducting diurnal spot samplings in summer 2016. Temperatures within the observed permanently wetted hyporheic zone (-56 to -100cm depth below GB surface) of the OSB, were warmer than both end members, surface water and groundwater >18% of the year, particularly during summer. There was a general increase in exceedance within the periodically wetted gravel bar sediment toward the gravel bar surface, further evidencing downward heat transfer to the wetted HZ. Average CO2 flux from the GB was significantly higher than that of streamwater during summer and winter, with significantly higher temperatures and CO2 outgassing rates occurring at the GB tail as compared to streamwater and the head and mid of the GB throughout the year. Higher cumulative (over 6 h) GB seasonal temperatures were associated with increased CO2 evasion fluxes within the OSB, particularly during summer. This enhanced CO2 flux may result from the input of warmer CO2-rich groundwater into the HZ in autumn, while downward heat transfer in summer may enhance GB metabolism and therefore CO2 evasion. Furthermore, catchment CO2 outgassing fluxes significantly exceeded that of the stream, with higher diurnal CO2 outgassing fluxes observed for all 13 GBs within the Ybbs and Erlauf catchments as compared to their respective streams. We found DOC concentration did not significantly correlate to CO2 outgassing. But, vertical temperature gradient as a measure of heat flux to the hyporheic zone explained 55% and 69% of the variability in observed CO2 efflux from the OSB gravel bar (seasonal samplings during summer 2015 - winter 2016) and 11 catchment gravel bars (2 GBs excluded due to equipment malfunction) respectively. These results highlight the effect of temperature on physical and biochemical stream processes, particularly in cold-water streams, due to the occurrence of more frequent and intense warm temperature events, as well as altered flow regimes, likely consequences of climatic change.

The low-lying quartet electronic states of group 14 diatomic borides XB (X = C, Si, Ge, Sn, Pb)

NASA Astrophysics Data System (ADS)

Pontes, Marcelo A. P.; de Oliveira, Marcos H.; Fernandes, Gabriel F. S.; Da Motta Neto, Joaquim D.; Ferrão, Luiz F. A.; Machado, Francisco B. C.

2018-04-01

The present work focuses in the characterization of the low-lying quartet electronic and spin-orbit states of diatomic borides XB, in which X is an element of group 14 (C, Si, Ge, Sn, PB). The wavefunction was obtained at the CASSCF/MRCI level with a quintuple-ζ quality basis set. Scalar relativistic effects were also taken into account. A systematic and comparative analysis of the spectroscopic properties for the title molecular series was carried out, showing that the (1)4Π→X4Σ- transition band is expected to be measurable by emission spectroscopy to the GeB, SnB and PbB molecules, as already observed for the lighter CB and SiB species.

Probing the superconducting ground state of the rare-earth ternary boride superconductors R RuB2 (R = Lu,Y) using muon-spin rotation and relaxation

NASA Astrophysics Data System (ADS)

Barker, J. A. T.; Singh, R. P.; Hillier, A. D.; Paul, D. McK.

2018-03-01

The superconductivity in the rare-earth transition-metal ternary borides R RuB2 (where R =Lu and Y) has been investigated using muon-spin rotation and relaxation. Measurements made in zero field suggest that time-reversal symmetry is preserved upon entering the superconducting state in both materials; a small difference in depolarization is observed above and below the superconducting transition in both compounds, however, this has been attributed to quasistatic magnetic fluctuations. Transverse-field measurements of the flux-line lattice indicate that the superconductivity in both materials is fully gapped, with a conventional s -wave pairing symmetry and BCS-like magnitudes for the zero-temperature gap energies. The electronic properties of the charge carriers in the superconducting state have been calculated, with effective masses m*/me=9.8 ±0.1 and 15.0 ±0.1 in the Lu and Y compounds, respectively, with superconducting carrier densities ns=(2.73 ±0.04 ) ×1028m-3 and (2.17 ±0.02 ) ×1028m-3 . The materials have been classified according to the Uemura scheme for superconductivity, with values for Tc/TF of 1 /(414 ±6 ) and 1 /(304 ±3 ) , implying that the superconductivity may not be entirely conventional in nature.

Element Distribution in the Oxygen-Rich Side-Blow Bath Smelting of a Low-Grade Bismuth-Lead Concentrate

NASA Astrophysics Data System (ADS)

Yang, Tianzu; Xiao, Hui; Chen, Lin; Chen, Wei; Liu, Weifeng; Zhang, Duchao

2018-03-01

Oxygen-rich side-blow bath smelting (OSBS) technology offers an efficient method for processing complex bismuth-lead concentrates; however, the element distributions in the process remain unclear. This work determined the distributions of elements, i.e., bismuth, lead, silver, copper, arsenic and antimony, in an industrial-scale OSBS process. The feed, oxidized slag and final products were collected from the respective sampling points and analyzed. For the oxidative smelting process, 65% of bismuth and 76% of silver in the concentrate report to the metal alloy, whereas less lead reports to the metal ( 31%) than the oxidized slag ( 44%). Approximately 50% of copper enters the matte, while more than 63% of arsenic and antimony report to the slag. For the reductive smelting process, less than 4.5% of bismuth, lead, silver and copper in the oxidized slag enter the reduced slag, indicating high recoveries of these metal values.

Element Distribution in the Oxygen-Rich Side-Blow Bath Smelting of a Low-Grade Bismuth-Lead Concentrate

NASA Astrophysics Data System (ADS)

Yang, Tianzu; Xiao, Hui; Chen, Lin; Chen, Wei; Liu, Weifeng; Zhang, Duchao

2018-06-01

Oxygen-rich side-blow bath smelting (OSBS) technology offers an efficient method for processing complex bismuth-lead concentrates; however, the element distributions in the process remain unclear. This work determined the distributions of elements, i.e., bismuth, lead, silver, copper, arsenic and antimony, in an industrial-scale OSBS process. The feed, oxidized slag and final products were collected from the respective sampling points and analyzed. For the oxidative smelting process, 65% of bismuth and 76% of silver in the concentrate report to the metal alloy, whereas less lead reports to the metal ( 31%) than the oxidized slag ( 44%). Approximately 50% of copper enters the matte, while more than 63% of arsenic and antimony report to the slag. For the reductive smelting process, less than 4.5% of bismuth, lead, silver and copper in the oxidized slag enter the reduced slag, indicating high recoveries of these metal values.

Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

DOE PAGES

Ghafoor, Naureen; Eriksson, Fredrik; Aquila, Andrew; ...

2017-01-01

We investigate the influence of B 4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization nearmore » Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.« less

Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghafoor, Naureen; Eriksson, Fredrik; Aquila, Andrew

We investigate the influence of B 4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization nearmore » Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.« less

Fracture Strength of AlLiB14

NASA Astrophysics Data System (ADS)

Wan, L. F.; Beckman, S. P.

2012-10-01

The orthorhombic boride crystal family XYB14, where X and Y are metal atoms, plays a critical role in a unique class of superhard compounds, yet there have been no studies aimed at understanding the origin of the mechanical strength of this compound. We present here the results from a comprehensive investigation into the fracture strength of the archetypal AlLiB14 crystal. First principles, ab initio, methods are used to determine the ideal brittle cleavage strength for several high-symmetry orientations. The elastic tensor and the orientation-dependent Young’s modulus are calculated. From these results the lower bound fracture strength of AlLiB14 is predicted to be between 29 and 31 GPa, which is near the measured hardness reported in the literature. These results indicate that the intrinsic strength of AlLiB14 is limited by the interatomic B-B bonds that span between the B layers.

SABER: A computational method for identifying active sites for new reactions

PubMed Central

Nosrati, Geoffrey R; Houk, K N

2012-01-01

A software suite, SABER (Selection of Active/Binding sites for Enzyme Redesign), has been developed for the analysis of atomic geometries in protein structures, using a geometric hashing algorithm (Barker and Thornton, Bioinformatics 2003;19:1644–1649). SABER is used to explore the Protein Data Bank (PDB) to locate proteins with a specific 3D arrangement of catalytic groups to identify active sites that might be redesigned to catalyze new reactions. As a proof-of-principle test, SABER was used to identify enzymes that have the same catalytic group arrangement present in o-succinyl benzoate synthase (OSBS). Among the highest-scoring scaffolds identified by the SABER search for enzymes with the same catalytic group arrangement as OSBS were l-Ala d/l-Glu epimerase (AEE) and muconate lactonizing enzyme II (MLE), both of which have been redesigned to become effective OSBS catalysts, demonstrated by experiments. Next, we used SABER to search for naturally existing active sites in the PDB with catalytic groups similar to those present in the designed Kemp elimination enzyme KE07. From over 2000 geometric matches to the KE07 active site, SABER identified 23 matches that corresponded to residues from known active sites. The best of these matches, with a 0.28 Å catalytic atom RMSD to KE07, was then redesigned to be compatible with the Kemp elimination using RosettaDesign. We also used SABER to search for potential Kemp eliminases using a theozyme predicted to provide a greater rate acceleration than the active site of KE07, and used Rosetta to create a design based on the proteins identified. PMID:22492397

Mechanistic Insights from the Crystal Structure of Bacillus subtilis o-Succinylbenzoyl-CoA Synthetase Complexed with the Adenylate Intermediate.

PubMed

Chen, Yaozong; Jiang, Yiping; Guo, Zhihong

2016-12-06

o-Succinylbenzoyl-CoA (OSB-CoA) synthetase, or MenE, catalyzes an essential step in vitamin K biosynthesis and is a valuable drug target. Like many other adenylating enzymes, it changes its structure to accommodate substrate binding, catalysis, and product release along the path of a domain alternation catalytic mechanism. We have determined the crystal structure of its complex with the adenylation product, o-succinylbenzoyl-adenosine monophosphate (OSB-AMP), and captured a new postadenylation state. This structure presents unique features such as a strained conformation for the bound adenylate intermediate to indicate that it represents the enzyme state after completion of the adenylation reaction but before release of the C domain in its transition to the thioesterification conformation. By comparison to the ATP-bound preadenylation conformation, structural changes are identified in both the reactants and the active site to allow inference about how these changes accommodate and facilitate the adenylation reaction and to directly support an in-line backside attack nucleophilic substitution mechanism for the first half-reaction. Mutational analysis suggests that the conserved His196 plays an important role in desolvation of the active site rather than stabilizing the transition state of the adenylation reaction. In addition, comparison of the new structure with a previously determined OSB-AMP-bound structure of the same enzyme allows us to propose a release mechanism of the C domain in its alteration to form the thioesterification conformation. These findings allow us to better understand the domain alternation catalytic mechanism of MenE as well as many other adenylating enzymes.

Histology after lumpectomy in women with epithelial atypia on stereotactic vacuum-assisted breast biopsy.

PubMed

Graesslin, O; Antoine, M; Chopier, J; Seror, J Y; Flahault, A; Callard, P; Daraï, E; Uzan, S

2010-02-01

Large-core needle biopsy of the breast (LCNB) and vacuum-assisted breast biopsy (VABB) are widely used as alternatives to open surgical biopsy (OSB) for initial diagnosis of mammographic abnormalities. Between 18% and 80% of cases in which such specimens show atypical lobular hyperplasia (ALH) or atypical ductal hyperplasia (ADH) are found to be malignant at surgery. From 1999 to 2005, 68 women with mammographic abnormalities were sampled by stereotactic VABB and presented atypical epithelial hyperplasia. Immunohistochemical staining with anti-cytokeratin 5/6 and anti-E-cadherin antibodies was performed. All women underwent a lumpectomy. Clinical, radiological or histological factors predictive of the risk of finding malignancy at surgery were sought. VABB initially showed 28 cases of ADH, 32 cases of ALH, one case of flat epithelial atypia, five cases of mixed atypia, and two cases of Lobular Carcinoma In Situ (LCIS). After slide review with immunohistochemical staining, two cases of ADH were reclassified as simple hyperplasia and two cases of ALH were reclassified as mixed atypia. Seven lesions (10.3%) that appeared to be benign on VABB were found to be malignant on OSB (Ductal Carcinoma In Situ (DCIS) in six cases and invasive ductal carcinoma in one case). ADH was the only predictive factor of malignancy on OSB (p=0.04 versus ALH). ADH diagnosed by vacuum-assisted breast biopsy frequently corresponds to cancer on open surgical biopsy. Surgical excision of all breast lesions containing atypical hyperplasia on percutaneous biopsy can be recommended. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Ternary boride product and process

NASA Technical Reports Server (NTRS)

Clougherty, Edward V. (Inventor)

1976-01-01

A hard, tough, strong ceramic body is formed by hot pressing a mixture of a powdered metal and a powdered metal diboride. The metal employed is zirconium, titanium or hafnium and the diboride is the diboride of a different member of the same group of zirconium, titanium or hafnium to form a ternary composition. During hot pressing at temperatures above about 2,000.degree.F., a substantial proportion of acicular ternary monoboride is formed.

Fundamental Thermal and Mechanical Properties of Boride Ceramics

DTIC Science & Technology

2014-02-28

Zr ,Y)B2 ( Zr ,Hf)B2 ( Zr ,Ti)B2 ZrB2 El ec tri ca l R es is tiv ity (µ Ω -c m ) Temperature (°C) Figure 17. Electrical resistivity as a function...family as Zr , namely Ti and Hf, had minimal effect on thermal conductivity, while others such as Nb , Ta, and W had an increasing impact based on their...diffusivity (α), heat capacity (Cp) from the NIST-JANAF tables, and bulk density (ρ) using Equation 6. (5) (6) Electrical resistivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mbarki, Mohammed; Touzani, Rachid St.; Rehorn, Christian W.G.

The new ternary transition metal-rich borides Ta{sub 2}OsB{sub 2} and TaRuB have been successfully synthesized by arc-melting the elements in a water-cooled crucible under an argon atmosphere. The crystal structures of both compounds were solved by single-crystal X-ray diffraction and their metal compositions were confirmed by EDX analysis. It was found that Ta{sub 2}OsB{sub 2} and TaRuB crystallize in the tetragonal Nb{sub 2}OsB{sub 2} (space group P4/mnc, no. 128) and the orthorhombic NbRuB (space group Pmma, no. 51) structure types with lattice parameters a=5.878(2) Å, c=6.857(2) Å and a=10.806(2) Å, b=3.196(1) Å, c=6.312(2) Å, respectively. Furthermore, crystallographic, electronic and bondingmore » characteristics have been studied by density functional theory (DFT). Electronic structure relaxation has confirmed the crystallographic parameters while COHP bonding analysis indicates that B{sub 2}-dummbells are the strongest bonds in both compounds. Moreover, the formation of osmium dumbbells in Ta{sub 2}OsB{sub 2} through a Peierls distortion along the c-axis, is found to be the origin of superstructure formation. Magnetic susceptibility measurements reveal that the two phases are Pauli paramagnets, thus confirming the theoretical DOS prediction of metallic character. Also hints of superconductivity are found in the two phases, however lack of single phase samples has prevented confirmation. Furthermore, the thermodynamic stability of the two modifications of AMB (A=Nb, Ta; M =Ru, Os) are studied using DFT, as new possible phases containing either B{sub 4}- or B{sub 2}-units are predicted, the former being the most thermodynamically stable modification. - Graphical abstract: The two new ternary tantalum borides, Ta{sub 2}OsB{sub 2} and TaRuB, have been discovered. Their crystal structures contain boron dumbbells, which are the strongest bonds. Peirls distortion is found responsible for Os{sub 2}-dumbbells formation in Ta{sub 2}OsB{sub 2}. Ta{sub 2}OsB{sub 2} and TaRuB are Pauli paramagnet and potential superconductors. - Highlights: • Two new ternary tantalum borides, Ta{sub 2}OsB{sub 2} and TaRuB, discovered. • Boron dumbbells are the strongest bonds in Ta{sub 2}OsB{sub 2} and TaRuB. • Peierls distortion responsible for Os{sub 2}-dumbbells formation in Ta{sub 2}OsB{sub 2.} • Ta{sub 2}OsB{sub 2} and TaRuB are Pauli paramagnet. • Ta{sub 2}OsB{sub 2} and TaRuB contain pseudogaps and are potential superconductors.« less

Boron oxynitride nanoclusters on tungsten trioxide as a metal-free cocatalyst for photocatalytic oxygen evolution from water splitting

NASA Astrophysics Data System (ADS)

Xie, Ying Peng; Liu, Gang; Lu, Gao Qing (Max); Cheng, Hui-Ming

2012-02-01

Here we show that B2O3-xNx nanoclusters can be formed on the surface of WO3 particles by a combination of thermal oxidation of tungsten boride (WB) in air and the subsequent nitriding process in gaseous ammonia. The resultant nanoclusters are found to play an apparent role in improving the photocatalytic oxygen evolution of WO3 by promoting the surface separation of photoexcited charge-carriers.Here we show that B2O3-xNx nanoclusters can be formed on the surface of WO3 particles by a combination of thermal oxidation of tungsten boride (WB) in air and the subsequent nitriding process in gaseous ammonia. The resultant nanoclusters are found to play an apparent role in improving the photocatalytic oxygen evolution of WO3 by promoting the surface separation of photoexcited charge-carriers. Electronic supplementary information (ESI) available: (1) Experimental section. (2) XRD patterns, FT-IR and Raman spectra of B2O3@WO3 and B2O3-xNx@WO3. (3) Time course of O2 evolution from water splitting using B2O3@WO3 and B2O3-xNx@WO3. (4) XRD pattern and SEM image of pure WO3, UV-visible absorption spectra of pure WO3 and N-WO3. (5) UV-visible absorption spectra of bulk B2O3 and schematic of band edges of WO3, bulk B2O3, and B2O3-xNx nanocluster. See DOI: 10.1039/c2nr11846g

DOE Zero Energy Ready Home Case Study: John Hubert Associates — EXIT-0 House, North Cape May, NJ

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

This house is the first DOE Zero Energy Ready Home for this builder and won a Custom Builder award in the 2014 Housing Innovation Awards. The 1,871-ft2 home features advanced-framed above-grade walls with R-21 fiberglass batt plus an R-3.6-insulated coated OSB sheathing, R-18 rigid-foam-insulated crawlspace walls, solar water heating, a high-efficiency heat pump, an HRV, and mostly LED lighting.

The Structural Insulated Panel SIP Hut: Preliminary Evaluation of Energy Efficiency and Indoor Air Quality

DTIC Science & Technology

2015-08-19

laboratory analysis using EPA TO-15, and collection of gas samples in sorbent tubes for later analysis of aldehydes using NIOSH Method 2016. Total VOCs...measurement can be a general qualitative indicator of IAQ problems; formaldehyde and other aldehydes are common organic gases emitted from OSB; and...table in the middle of the hut. 5.1.2.3 Formaldehyde and other aldehydes Aldehydes were measured using both Dräger-tubes and by NIOSH Method 2016. The

NASA research on refractory compounds.

NASA Technical Reports Server (NTRS)

Gangler, J. J.

1971-01-01

The behavior and properties of the refractory carbides, nitrides, and borides are being investigated by NASA as part of its research aimed at developing superior heat resistant materials for aerospace applications. Studies of the zirconium-carbon-oxygen system show that zirconium oxycarbides of different compositions and lattice parameters can be formed between 1500 C and 1900 C and are stable below 1500 C. More applied studies show that hot working generally improves the microstructure and therefore the strength of TiC and NbC. Sintering studies on UN indicate that very high densities can be achieved. Hot pressing of cermets of HfN and HfC produces good mechanical properties for high temperature bearing applications. Attempts to improve the impact resistance of boride composites by the addition of a nickel or carbon yarn were not overly successful.

Ceramic fibers from Si-B-C polymer precursors

NASA Technical Reports Server (NTRS)

Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

1993-01-01

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

Ternary ceramic thermal spraying powder and method of manufacturing thermal sprayed coating using said powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogli, Evelina; Sherman, Andrew J.; Glasgow, Curtis P.

The invention describes a method for producing ternary and binary ceramic powders and their thermal spraying capable of manufacturing thermal sprayed coatings with superior properties. Powder contain at least 30% by weight ternary ceramic, at least 20% by weight binary molybdenum borides, at least one of the binary borides of Cr, Fe, Ni, W and Co and a maximum of 10% by weight of nano and submicro-sized boron nitride. The primary crystal phase of the manufactured thermal sprayed coatings from these powders is a ternary ceramic, while the secondary phases are binary ceramics. The coatings have extremely high resistance againstmore » corrosion of molten metal, extremely thermal shock resistance and superior tribological properties at low and at high temperatures.« less

Design of Wear-Resistant Austenitic Steels for Selective Laser Melting

NASA Astrophysics Data System (ADS)

Lemke, J. N.; Casati, R.; Lecis, N.; Andrianopoli, C.; Varone, A.; Montanari, R.; Vedani, M.

2018-03-01

Type 316L stainless steel feedstock powder was modified by alloying with powders containing carbide/boride-forming elements to create improved wear-resistant austenitic alloys that can be readily processed by Selective Laser Melting. Fe-based alloys with high C, B, V, and Nb contents were thus produced, resulting in a microstructure that consisted of austenitic grains and a significant amount of hard carbides and borides. Heat treatments were performed to modify the carbide distribution and morphology. Optimal hard-phase spheroidization was achieved by annealing the proposed alloys at 1150 °C for 1 hour followed by water quenching. The total increase in hardness of samples containing 20 pct of C/B-rich alloy powder was of 82.7 pct while the wear resistance could be increased by a factor of 6.

Osteocyte viability and regulation of osteoblast function in a 3D trabecular bone explant under dynamic hydrostatic pressure.

PubMed

Takai, Erica; Mauck, Robert L; Hung, Clark T; Guo, X Edward

2004-09-01

A new trabecular bone explant model was used to examine osteocyte-osteoblast interactions under DHP loading. DHP loading enhanced osteocyte viability as well as osteoblast function measured by osteoid formation. However, live osteocytes were necessary for osteoblasts to form osteoids in response to DHP, which directly show osteoblast-osteocyte interactions in this in vitro culture. A trabecular bone explant model was characterized and used to examine the effect of osteocyte and osteoblast interactions and dynamic hydrostatic pressure (DHP) loading on osteocyte viability and osteoblast function in long-term culture. Trabecular bone cores obtained from metacarpals of calves were cleaned of bone marrow and trabecular surface cells and divided into six groups, (1) live cores + dynamic hydrostatic pressure (DHP), (2) live cores + sham, (3) live cores + osteoblast + DHP, (4) live cores + osteoblast + sham, (5) devitalized cores + osteoblast + DHP, and (6) devitalized cores + osteoblast + sham, with four culture durations (2, 8, 15, and 22 days; n = 4/group). Cores from groups 3-6 were seeded with osteoblasts, and cores from groups 5 and 6 were devitalized before seeding. Groups 1, 3, and 5 were subjected to daily DHP loading. Bone histomorphometry was performed to quantify osteocyte viability based on morphology and to assess osteoblast function based on osteoid surface per bone surface (Os/Bs). TUNEL staining was performed to evaluate the mode of osteocyte death under various conditions. A portion of osteocytes remained viable for the duration of culture. DHP loading significantly enhanced osteocyte viability up to day 8, whereas the presence of seeded osteoblasts significantly decreased osteocyte viability. Cores with live osteocytes showed higher Os/Bs compared with devitalized cores, which reached significant levels over a greater range of time-points when combined with DHP loading. DHP loading did not increase Os/Bs in the absence of live osteocytes. The percentage of apoptotic cells remained the same regardless of treatment or culture duration. Enhanced osteocyte viability with DHP suggests the necessity of mechanical stimulation for osteocyte survival in vitro. Furthermore, osteocytes play a critical role in the transmission of signals from DHP loading to modulate osteoblast function. This explant culture model may be used for mechanotransduction studies in long-term cultures.

Correlation between thermodynamical stabilities of metal borohydrides and cation electronegativites: First-principles calculations and experiments

NASA Astrophysics Data System (ADS)

Nakamori, Yuko; Miwa, Kazutoshi; Ninomiya, Akihito; Li, Haiwen; Ohba, Nobuko; Towata, Shin-Ichi; Züttel, Andreas; Orimo, Shin-Ichi

2006-07-01

The thermodynamical stabilities for the series of metal borohydrides M(BH4)n ( M=Li , Na, K, Cu, Mg, Zn, Sc, Zr, and Hf; n=1-4 ) have been systematically investigated by first-principles calculations. The results indicated that an ionic bonding between Mn+ cations and [BH4]- anions exists in M(BH4)n , and the charge transfer from Mn+ cations to [BH4]- anions is a key feature for the stability of M(BH4)n . A good correlation between the heat of formation ΔHboro of M(BH4)n and the Pauling electronegativity of the cation χP can be found, which is represented by the linear relation, ΔHboro=248.7χP-390.8 in the unit of kJ/mol BH4 . In order to confirm the predicted correlation experimentally, the hydrogen desorption reactions were studied for M(BH4)n ( M=Li , Na, K, Mg, Zn, Sc, Zr, and Hf), where the samples of the later five borohydrides were mechanochemically synthesized. The thermal desorption analyses indicate that LiBH4 , NaBH4 , and KBH4 desorb hydrogen to hydride phases. Mg(BH4)2 , Sc(BH4)3 , and Zr(BH4)4 show multistep desorption reactions through the intermediate phases of hydrides and/or borides. On the other hand, Zn(BH4)2 desorbs hydrogen and borane to elemental Zn due to instabilities of Zn hydride and boride. A correlation between the desorption temperature Td and the Pauling electronegativity χP is observed experimentally and so χP is an indicator to approximately estimate the stability of M(BH4)n . The enthalpy change for the desorption reaction, ΔHdes , is estimated using the predicted ΔHboro and the reported data for decomposed product, ΔHhyd/boride . The estimated ΔHdes show a good correlation with the observed Td , indicating that the predicted stability of borohydride is experimentally supported. These results are useful for exploring M(BH4)n with appropriate stability as hydrogen storage materials.

Analysis of cytoplasmic genomes in somatic hybrids between navel orange (Citrus sinensis Osb.) and 'Murcott' tangor.

PubMed

Kobayashi, S; Ohgawara, T; Fujiwara, K; Oiyama, I

1991-07-01

Somatic hybrid plants were produced by protoplast fusion of navel orange and 'Murcott' tangor. Hybridity of the plants was confirmed by the restriction endonuclease analysis of nuclear ribosomal DNA. All of the plants (16 clones) were normal, uniform, and had the amphidiploid chromosome number of 36 (2n=2x=18 for each parent). The cpDNA analysis showed that each of the 16 somatic hybrids contained either one parental chloroplast genome or the other. In all cases, the mitochondrial genomes of the regenerated somatic hybrids were of the navel orange type.

Tetraploidy Enhances Boron-Excess Tolerance in Carrizo Citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.).

PubMed

Ruiz, Marta; Quiñones, Ana; Martínez-Alcántara, Belén; Aleza, Pablo; Morillon, Raphaël; Navarro, Luis; Primo-Millo, Eduardo; Martínez-Cuenca, Mary-Rus

2016-01-01

Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B) toxicity responses in diploid (2x) and tetraploid (4x) plants of Carrizo citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.), a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport. Tetraploidy enhances B excess tolerance in citrange CarrizoExpression of NIP5 and BOR1 transporters and cell wall-bounded B are similar between ploidiesB tolerance is attributed to root anatomical modifications induced by genome duplicationThe rootstock 4x citrange carrizo may prevent citrus trees from B excess.

Tetraploidy Enhances Boron-Excess Tolerance in Carrizo Citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.)

PubMed Central

Ruiz, Marta; Quiñones, Ana; Martínez-Alcántara, Belén; Aleza, Pablo; Morillon, Raphaël; Navarro, Luis; Primo-Millo, Eduardo; Martínez-Cuenca, Mary-Rus

2016-01-01

Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B) toxicity responses in diploid (2x) and tetraploid (4x) plants of Carrizo citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.), a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport. Highlights Tetraploidy enhances B excess tolerance in citrange Carrizo Expression of NIP5 and BOR1 transporters and cell wall-bounded B are similar between ploidies B tolerance is attributed to root anatomical modifications induced by genome duplication The rootstock 4x citrange carrizo may prevent citrus trees from B excess. PMID:27252717

Tetraploid Carrizo citrange rootstock (Citrus sinensis Osb.×Poncirus trifoliata L. Raf.) enhances natural chilling stress tolerance of common clementine (Citrus clementina Hort. ex Tan).

PubMed

Oustric, Julie; Morillon, Raphaël; Luro, François; Herbette, Stéphane; Lourkisti, Radia; Giannettini, Jean; Berti, Liliane; Santini, Jérémie

2017-07-01

Low temperatures can disturb the development, growth and geographic distribution of plants, particularly cold-sensitive plants in the Mediterranean area, where temperatures can reach seasonally low levels. In citrus crops, scion/rootstock combinations are used to improve fruit production and quality, and increase tolerance to biotic and abiotic stresses. In the last decade, several studies have shown that tetraploid citrus seedlings or rootstocks are more tolerant to abiotic stress than their respective diploid. The objective of this study was to test whether the use of tetraploid rootstocks can improve the chilling tolerance of the scion. We compared physiological and biochemical responses to low seasonal temperatures of common Clementine (Citrus sinensis Osb.×Poncirus trifoliata L. Raf.) grafted on diploid and tetraploid Carrizo citrange rootstocks, named C/2xCC and C/4xCC, respectively. During the coldest months, C/4xCC showed a smaller decrease in net photosynthesis (Pn), stomatal conductance (G s ), chlorophyll fluorescence (F v /F m ), and starch levels, and lower levels of malondialdehyde and electrolyte leakage than C/2xCC. Specific activities of catalase (CAT), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) were higher in C/4xCC during the cold period, whereas chlorophyll, proline, ascorbate and hydrogen peroxide (H 2 O 2 ) levels and superoxide dismutase (SOD) activity did not vary significantly between C/4xCC and C/2xCC throughout the study period. Taken together, these results demonstrate that tetraploid Carrizo citrange rootstock improves the chilling tolerance of common clementine (scion) thanks to a part of the antioxidant system. Copyright © 2017. Published by Elsevier GmbH.

NEUTRONIC REACTOR FUEL COMPOSITION

DOEpatents

Thurber, W.C.

1961-01-10

Uranium-aluminum alloys in which boron is homogeneously dispersed by adding it as a nickel boride are described. These compositions have particular utility as fuels for neutronic reactors, boron being present as a burnable poison.

A prospective study on fetal posterior cranial fossa assessment for early detection of open spina bifida at 11-13 weeks.

PubMed

Kose, Semir; Altunyurt, Sabahattin; Keskinoglu, Pembe

2018-01-01

The objective of this study was to test three measurements: brain stem (BS), intracranial translucency (IT) and brain stem to occipital bone distance (BSOB), as well as one landmark: cisterna magna (CM) visibility, for early diagnosis of open spina bifida (OSB) in a low risk population. A prospective observational study was undertaken in a university hospital. A sample of 1479 women consented to participate between 20 September 2013 and 30 June 2015. Measurements were performed from the mid-sagittal view, as is routinely used for nuchal thickness assessment. CM visibility was assessed qualitatively as the third anechoic band in the posterior cranial fossa (PCF). All pregnancies were screened with a combination of maternal serum alpha-fetoprotein and second trimester anomaly scan and followed until delivery. Predictive values were calculated for each marker. We were able to diagnose two OSB cases and highly suspect one Dandy-Walker malformation case at the first trimester scan by the observation of PCF. PCF characteristics of OSB cases were increased BS diameter, increased BS-BSOB ratio and non-visualization of the CM. All the markers demonstrated high sensitivity and specificity but CM visibility reached the highest positive predictive value. Due to relatively high false positive rates, PCF measurements could not reach a satisfactory performance to validate their clinical use as a single marker. CM visibility has the advantage of being a qualitative marker and reduces the need for sophisticated and time-consuming measurements. Intracranial translucency and BS-BSOB ratio measurements should be used when the CM visibility is absent or in doubt. © 2017 Japanese Teratology Society.

SABER: a computational method for identifying active sites for new reactions.

PubMed

Nosrati, Geoffrey R; Houk, K N

2012-05-01

A software suite, SABER (Selection of Active/Binding sites for Enzyme Redesign), has been developed for the analysis of atomic geometries in protein structures, using a geometric hashing algorithm (Barker and Thornton, Bioinformatics 2003;19:1644-1649). SABER is used to explore the Protein Data Bank (PDB) to locate proteins with a specific 3D arrangement of catalytic groups to identify active sites that might be redesigned to catalyze new reactions. As a proof-of-principle test, SABER was used to identify enzymes that have the same catalytic group arrangement present in o-succinyl benzoate synthase (OSBS). Among the highest-scoring scaffolds identified by the SABER search for enzymes with the same catalytic group arrangement as OSBS were L-Ala D/L-Glu epimerase (AEE) and muconate lactonizing enzyme II (MLE), both of which have been redesigned to become effective OSBS catalysts, demonstrated by experiments. Next, we used SABER to search for naturally existing active sites in the PDB with catalytic groups similar to those present in the designed Kemp elimination enzyme KE07. From over 2000 geometric matches to the KE07 active site, SABER identified 23 matches that corresponded to residues from known active sites. The best of these matches, with a 0.28 Å catalytic atom RMSD to KE07, was then redesigned to be compatible with the Kemp elimination using RosettaDesign. We also used SABER to search for potential Kemp eliminases using a theozyme predicted to provide a greater rate acceleration than the active site of KE07, and used Rosetta to create a design based on the proteins identified. Copyright © 2012 The Protein Society.

Technology of Strengthening Steel Details by Surfacing Composite Coatings

NASA Astrophysics Data System (ADS)

Burov, V. G.; Bataev, A. A.; Rakhimyanov, Kh M.; Mul, D. O.

2016-04-01

The article considers the problem of forming wear resistant meal ceramic coatings on steel surfaces using the results of our own investigations and the analysis of achievements made in the country and abroad. Increasing the wear resistance of surface layers of steel details is achieved by surfacing composite coatings with carbides or borides of metals as disperse particles in the strengthening phase. The use of surfacing on wearing machine details and mechanisms has a history of more than 100 years. But still engineering investigations in this field are being conducted up to now. The use of heating sources which provide a high density of power allows ensuring temperature and time conditions of surfacing under which composites with peculiar service and functional properties are formed. High concentration of energy in the zone of melt, which is created from powder mixtures and the hardened surface layer, allows producing the transition zone between the main material and surfaced coating. Surfacing by the electron beam directed from vacuum to the atmosphere is of considerable technological advantages. They give the possibility of strengthening surface layers of large-sized details by surfacing powder mixtures without their preliminary compacting. A modified layer of the main metal with ceramic particles distributed in it is created as a result of heating surfaced powders and the detail surface layer by the electron beam. Technology of surfacing allows using powders of refractory metals and graphite in the composition of powder mixtures. They interact with one another and form the particles of the hardening phase of the composition coating. The chemical composition of the main and surfaced materials is considered to be the main factor which determines the character of metallurgical processes in local zones of melt as well as the structure and properties of surfaced composition.

PREFACE: The 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008)

NASA Astrophysics Data System (ADS)

Tanaka, Takaho

2009-07-01

This volume of Journal of Physics: Conference Series contains invited and contributed peer-reviewed papers that were presented at the 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008), which was held on 7-12 September 2008, at Kunibiki Messe, Matsue, Japan. This triennial symposium has a half-century long history starting from the 1st meeting in 1959 at Asbury Park, New Jersey. We were very pleased to organize ISBB 2008, which gathered chemists, physicists, materials scientists as well as diamond and high-pressure researchers. This meeting had a strong background in the boron-related Japanese research history, which includes the discovery of superconductivity in MgB2 and development of Nd-Fe-B hard magnets and of YB66 soft X-ray monochromator. The scope of ISBB 2008 spans both basic and applied interdisciplinary research that is centered on boron, borides and related materials, and the collection of articles defines the state of the art in research on these materials. The topics are centered on: 1. Preparation of new materials (single crystals, thin films, nanostructures, ceramics, etc) under normal or extreme conditions. 2. Crystal structure and chemical bonding (new crystal structures, nonstoichiometry, defects, clusters, quantum-chemical calculations). 3. Physical and chemical properties (band structure, phonon spectra, superconductivity; optical, electrical, magnetic, emissive, mechanical properties; phase diagrams, thermodynamics, catalytic activity, etc) in a wide range of temperatures and pressures. 4. Applications and prospects (thermoelectric converters, composites, ceramics, coatings, etc) There were a few discoveries of new materials, such as nanomaterials, and developments in applications. Many contributions were related to 4f heavy Fermion systems of rare-earth borides. Exotic mechanisms of magnetism and Kondo effects have been discussed, which may indicate another direction of development of boride. Two special sessions, 'Boron chemistry' and 'Superconductivity', were also held at the symposium. The session on Boron chemistry was planned to honor the scientific work in boron chemistry of Professor J Bauer on the occasion of his retirement. Many recent results were discussed in the session, and Professor Bauer himself introduced novel rare-earth-boron-carbon compounds RE10B7C10 (RE = Gd - Er) in his lecture. In the latter session, on the basis of recent discoveries of superconductivity in MgB2 and in β-boron under high pressure, the superconductivity of boron and related materials was discussed and the superconductivity of boron-doped diamond was also addressed. More than 120 participants from 16 countries attended the ISBB 2008, and active presentations (22 invited, 33 oral and 68 posters) and discussions suggest that research on boron and borides is entering a new phase of development. This volume contains 46 articles from 52 submitted manuscripts. The reviewers were invited not only from symposium participants but also from specialists worldwide, and they did a great job of evaluating and commenting on the submitted manuscripts to maintain the highest quality standard of this volume. Recent discoveries of superconductivity in boron under high pressure, synthesis of a new allotrope of boron and of various boron and boride nanostructures will lead this highly interdisciplinary field of science, which will further grow and gain attention in terms of both basic and applied research. In this context, we are very much looking forward to the next symposium, which will be held in Istanbul, Turkey, in 2011, organized by Professor Onuralp Yucel, Istanbul Technical University. Turkey currently has the world highest share of borate production and is expected to be involved more in boron-related research. Acknowledgements We gratefully acknowledge the style improvement by Dr K Iakoubovskii, and sincerely thank Shimane Prefecture and Matsue City for their financial support. The symposium was also supported by Tokyo University of Science, Suwa and foundations including, the Kajima Foundation, Foundation for Promotion of Material Science and Technology of Japan and Nippon Sheet Glass Foundation for Materials Science and Engineering, as well as companies including JFE Steel Corporation, Shincron Co, Ltd, Toyo Kohan Co, Ltd, Fukuda Metal Foil and Powder Co, Ltd, Japan New Metals Co, Ltd, H C Starck Ltd and Fritsch Japan Co, Ltd. Editors Chair Takaho Tanaka (National Institute for Materials Science, Japan) Vice chairs Koun Shirai (Osaka University, Japan) Kaoru Kimura (The University of Tokyo, Japan) Ken-ichi Takagi (Tokyo City University, Japan) Touetsu Shishido (Tohoku University, Japan) Shigeru Okada (Kokushikan University) Hideaki Itoh (Nagoya University,Japan) Katsumitsu Nakamura (Nihon University, Japan) Organizing committee of ISBB 2008 K Takagi Chairman (Tokyo City University) T Tanaka Program Committee Chairman (National Institute for Materials Science) K Kimura Secretary (The University of Tokyo) J Akimitsu (Aoyama University)K Shirai (Osaka University) H Itoh (Nagoya University)T Shishido (Tohoku University) K Nakamura (Nihon University)K Soga (Tokyo University of Science) K Nishiyama (Tokyo University of Science, Suwa)M Takeda (Nagaoka University of Technology) S Okada (Kokushikan University)Y Yamazaki (Toyo Kohan Co, Ltd) International Scientific Committee 0f ISBB (2008-2011) K Takagi Chairman (Japan) B Albert (Germany) J-F Halet (France) M Takeda (Japan) M Antadze (Georgia) H Hillebrecht (Germany) T Tanaka (Japan) J Bauer (France) W Jung (Germany) R Telle (Germany) I Boustani (Germany) K Kimura (Japan) M Trenary (USA) D Emin (USA) T Mori (Japan) O Tsagareishvili (Georgia) M Engler (Germany) P D Ownby (USA) H Werheit (Germany) N Frage (Israel) P Rogl (Austria) G Will (Germany) Yu Grin (Germany) S Shalamberidze (Georgia) O Yucel (Turkey) V N Gurin (Russia) N Shitsevalova (Ukraine) G Zhang (China)

Chemical precursors to non-oxide ceramics: Macro to nanoscale materials

NASA Astrophysics Data System (ADS)

Forsthoefel, Kersten M.

Non-oxide ceramics exhibit a number of important properties that make them ideal for technologically important applications (thermal and chemical stability, high strength and hardness, wear-resistance, light weight, and a range of electronic and optical properties). Unfortunately, traditional methodologies to these types of materials are limited to fairly simple shapes and complex processed forms cannot be attained through these methods. The establishment of the polymeric precursor approach has allowed for the generation of advanced materials, such as refractory non-oxide ceramics, with controlled compositions, under moderate conditions, and in processed forms. The goal of the work described in this dissertation was both to develop new processible precursors to technologically important ceramics and to achieve the formation of advanced materials in processed forms. One aspect of this research exploited previously developed preceramic precursors to boron carbide, boron nitride and silicon carbide for the generation of a wide variety of advanced materials: (1) ultra-high temperature ceramic (UHTC) structural materials composed of hafnium boride and related composite materials, (2) the quaternary borocarbide superconductors, and (3) on the nanoscale, non-oxide ceramic nanotubules. The generation of the UHTC and the quaternary borocarbide materials was achieved through a method that employs a processible polymer/metal(s) dispersion followed by subsequent pyrolyses. In the case of the UHTC, hafnium oxide, hafnium, or hafnium boride powders were dispersed in a suitable precursor to afford hafnium borides or related composite materials (HfB2/HfC, HfB2/HfN, HfB2/SiC) in high yields and purities. The quaternary borocarbide superconducting materials were produced from pyrolyses of dispersions containing appropriate stoichiometric amounts of transition metal, lanthanide metal, and the polyhexenyldecaborane polymer. Both chemical vapor deposition (CVD) based routes employing a molecular precursor and porous alumina templating routes paired with solution-based methodologies are shown to generate non-oxide ceramic nanotubules of boron carbide, boron nitride and silicon carbide compositions. In the final phase of this work, a new metal-catalyzed route to poly(1-alkenyl- o-carborane) homopolymers and related copolymers was developed. Both homopolymers of 1-alkenyl-o-carboranes (1-vinyl-, 1-butenyl-, 1-hexenyl-) and copolymers of 1-hexenyl-o-carborane and allyltrimethylsilane or 1-hexenyl-o-carborane and 6-hexenyldecaborane were synthesized via the Cp2ZrMe2/B(C6F5) 3 catalyst system. A copolymer containing 1-hexenyl-o-carborane and the cross-linking agent, 6-hexenyldecaborane, was synthetically designed which exhibits initial cross-linking at ˜250°C and then converts in 75% yields to boron carbide at 1250°C.

X-Ray photoelectron spectroscopy study of radiofrequency-sputtered titanium, carbide, molybdenum carbide, and titanium boride coatings and their friction properties

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1977-01-01

Radiofrequency sputtered coatings of titanium carbide, molybdenum carbide and titanium boride were tested as wear resistant coatings on stainless steel in a pin on disk apparatus. X-ray photoelectron spectroscopy (XPS) was used to analyze the sputtered films with regard to both bulk and interface composition in order to obtain maximum film performance. Significant improvements in friction behavior were obtained when properly biased films were deposited on deliberately preoxidized substrates. XPS depth profile data showed thick graded interfaces for bias deposited films even when adherence was poor. The addition of 10 percent hydrogen to the sputtering gas produced coatings with thin poorly adherent interfaces. Results suggest that some of the common practices in the field of sputtering may be detrimental to achieving maximum adherence and optimum composition for these refractory compounds.

Fusion welding of a modern borated stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robino, C.V.; Cieslak, M.J.

1997-01-01

Experiments designed to assess the fabrication and service weldability of 304B4A borated stainless steel were conducted. Welding procedures and parameters for manual gas tungsten arc (GTA) welding, autogenous electron beam (EB) welding and filler-added EB welding were developed and found to be similar to those for austenitic stainless steels. Following the procedure development, four test welds were produced and evaluated by microstructural analysis and Charpy impact testing. Further samples were used for determination of the postweld heat treatment (PWHT) response of the welds. The fusion zone structure of welds in this alloy consists of primary austenite dendrites with an interdendriticmore » eutectic-like austenite/boride constituent. Welds also show an appreciable partially molten zone that consists of the austenite/boride eutectic surrounding unmelted austenite islands. The microstructure of the EB welds was substantially finer than that of the GTA welds, and boride coarsening was not observed in the solid state heat-affected zone (HAZ) of either weld type. The impact toughness of as-welded samples was found to be relatively poor, averaging less than 10 J for both GTA and EB welds. For fusion zone notched GTA and EB samples and centerline notched EB samples, fracture generally occurred along the boundary between the partially molten and solid-state regions of the HAZ. The results of the PWHT study were very encouraging, with typical values of the impact energy for HAZ notched samples approaching 40 J, or twice the minimum code-acceptable value.« less

Interpenetration of a 3D Icosahedral M@Ni12 (M=Al, Ga) Framework with Porphyrin-Reminiscent Boron Layers in MNi9 B8.

PubMed

Zheng, Qiang; Wagner, Frank R; Ormeci, Alim; Prots, Yurii; Burkhardt, Ulrich; Schmidt, Marcus; Schnelle, Walter; Grin, Yuri; Leithe-Jasper, Andreas

2015-11-09

Two ternary borides MNi9 B8 (M=Al, Ga) were synthesized by thermal treatment of mixtures of the elements. Single-crystal X-ray diffraction data reveal AlNi9 B8 and GaNi9 B8 crystallizing in a new type of structure within the space group Cmcm and the lattice parameters a=7.0896(3) Å, b=8.1181(3) Å, c=10.6497(4) Å and a=7.0897(5) Å, b=8.1579(4) Å, c=10.6648(7) Å, respectively. The boron atoms build up two-dimensional layers, which consist of puckered [B16 ] rings with two tailing B atoms, whereas the M atoms reside in distorted vertices-condensed [Ni12 ] icosahedra, which form a three-dimensional framework interpenetrated by boron porphyrin-reminiscent layers. An unusual local arrangement resembling a giant metallo-porphyrin entity is formed by the [B16 ] rings, which, due to their large annular size of approximately 8 Å, chelate four of the twelve icosahedral Ni atoms. An analysis of the chemical bonding by means of the electron localizability approach reveals strong covalent B-B interactions and weak Ni-Ni interactions. Multi-center dative B-Ni interaction occurs between the Al-Ni framework and the boron layers. In agreement with the chemical bonding analysis and band structure calculations, AlNi9 B8 is a Pauli-paramagnetic metal. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance of Steel Stud Walls Subjected to Blast Loads

DTIC Science & Technology

2010-02-01

be used as load-bearing components or non-load-bearing components, and a variety of exterior finishes and internal sheathing may be used. From an...common sheathing materials such as drywall , oriented strand board (OSB), stucco, etc., utilizing conventional structural connections (e.g., slip

Occupational exposure characterization in professional sprayers: clinical utility of oxidative stress biomarkers.

PubMed

Astiz, Mariana; Arnal, Nathalie; de Alaniz, María J T; Marra, Carlos Alberto

2011-09-01

The impact of involuntary exposure to pesticides was studied in a group of professional sprayers (S) (25±5 years old) exposed to various agrochemicals for about 10 years. The results were compared with a group of non exposed people (C). S group showed hematological, renal, pancreatic and hepatic biomarkers within the reference values established for the general population, including cholinesterase activity. In spite of that, all the biochemical tests were statistically different compared to C. On the other hand, oxidative stress biomarkers (OSB) such as plasma tocopherol and the total reducing ability of plasma were significantly decreased, while protein carbonyls, thiobarbituric acid-reactive substances, total glutathione and the sum of nitrites and nitrates were increased in the exposed group. Results demonstrated that screening laboratory tests could not be fully sensitive in detecting sub-clinical exposure to pesticides, and also suggest that OSB could be validated and included in health surveillance protocols. Copyright © 2011 Elsevier B.V. All rights reserved.

Feasibility study of the welding of SiC

NASA Technical Reports Server (NTRS)

Moore, T. J.

1985-01-01

In a brief study of the feasibility of welding sintered alpha-SiC, solid-state welding and brazing were investigated. Joint quality was determined solely by microstructural examination. Hot-pressure welding was shown to be feasible at 1950 C. Diffusion welding and brazing were also successful under hot isostatic pressure at 1950 C when boride, carbide, and silicide interlayers were used. Furnace brazing was accomplished at 1750 C when a TiSi2 interlayer was introduced.

Titanium Diboride Electrodeposited Coatings

DTIC Science & Technology

1977-06-01

4 Ti02. This material was deposited in the form of a porous mass or loose particles which must be leached in water and acid to remove adherent...poudres metallique par electrolyse ignee. Revue de Metallurgie, v. 45, 1948, p. 49-59. 7. POWELL, C. F. Borides in High Temperature Materials and... water solution of thallium formate-thallium malonate 50-50 mole percent mixture with a density ranging from about 5 g/cm^ at the bottom to about 2 g/cm

First principle study of UHTC ternary diboride, Cr2AlB2

NASA Astrophysics Data System (ADS)

Rastogi, Anugya; Rajpoot, Priyanka; Verma, U. P.

2018-04-01

In this paper ab-initio study of the structural, electronic and optical properties of ternary metal boride Cr2AlB2 using full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The study of structural properties shows that Cr2AlB2 is metallic in nature and have orthorhombic crystal structure. The optical properties show that it possess anisotropic behavior, which have wide applications in electricity production through concentration of solar power (CSP) technology. To the best of our knowledge, theoretical study of the optical properties of Cr2AlB2 is reported for the first time.

Mechanism-based inhibitors of MenE, an acyl-CoA synthetase involved in bacterial menaquinone biosynthesis†

PubMed Central

Lu, Xuequan; Zhang, Huaning; Tonge, Peter J.; Tan, Derek S.

2008-01-01

Menaquinone (vitamin K2) is an essential component of the electron transfer chain in many pathogens, including Mycobacterium tuberculosis and Staphylococcus aureus, and menaquinone biosynthesis is a potential target for antibiotic drug discovery. We report herein a series of mechanism-based inhibitors of MenE, an acyl-CoA synthetase that catalyzes adenylation and thioesterification of o-succinylbenzoic acid (OSB) during menaquinone biosynthesis. The most potent compound inhibits MenE with an IC50 value of 5.7 μM. PMID:18762421

Isocyanate and total inhalable particulate air measurements in the European wood panel industry.

PubMed

Vangronsveld, E; Berckmans, S; Verbinnen, K; Van Leeuw, C; Bormans, C

2010-11-01

It is well known that the use of MDI (methylene diphenyldiisocyanate) as an alternative for formaldehyde-based resins is seen as a responsible option to reduce formaldehyde emissions for CWP (Composite Wood Products) in buildings. However, there are concerns raised regarding the exposure risk of workers. The purpose of this article is to provide the reader with factual information to demonstrate that the use of MDI compared to other agents used in CWP production processes does not pose increased inhalation exposure risks for workers. Personal and area air measurements were carried out at nine Composite Wood Panel plants throughout Europe to assess potential inhalation exposures to MDI and wood dust as Total Inhalable Particulates (TIP). In total, 446 pairs of samples were collected for MDI and TIP of which 283 pairs were personal samples and the remaining 163 pairs were area samples collected at key locations along the production line. This data together with published formaldehyde exposure data has been used to evaluate the exposure safety margin opposite what are considered relevant occupational exposure limits. The methods used for sampling and analysing MDI and TIP are based on internationally accepted methods, i.e. MDHS 25/3 (or ISO 16702) for MDI, and MDHS 14/3 for TIP. The job functions with an increased exposure profile for TIP were the cleaners, drying operators and quality control staff, and for MDI, the cleaners and quality control staff. The areas with an increased exposure profile for TIP are the conveyor area from OSB blender to former area and the OSB press infeed, and for MDI the OSB weigh belt and OSB former bin area. The exposure safety margin opposite the selected exposure limits can be ranked as MDI>TIP>formaldehyde (high margin of safety to low margin of safety), indicating that the use of MDI also reduces the exposure risks to workers during production of CWP compared to formaldehyde. By reducing the airborne TIP concentrations, a respiratory sensitiser, MDI workplace concentrations in general can be reduced further. This can be achieved by improving design and/or maintenance and testing programmes of existing control measures, which should be in place already to effectively control exposure to TIP and formaldehyde. The airborne concentration of MDI at workstations situated after pressing (curing) is regarded as extremely low and likely mainly constituted by workplace emissions from elsewhere in the plant. Copyright © 2010 Elsevier GmbH. All rights reserved.

Researches on tungsten carbide

NASA Astrophysics Data System (ADS)

1994-11-01

This paper summarizes results of the researches on tungsten carbide (WC), carried out in the 5-year period starting 1989 by the Science and Technology Agency's National Institute for Researches in Inorganic Materials. The high-frequency heating, floating zone technique, generally suited for growth of large-size, single crystals of high melting materials, is inapplicable to the hexagonal WC system, which is decomposed. This problem has been solved by adding boron to the system, to allow it to exist with the W-C-B melt at an equilibrium. The computer-aided control techniques have enabled automatic growth of the single crystals of carbides and borides. The de Haas-Van Alphen effect of the single WC crystals has been observed, to establish the Fermi surface model. The single crystals of transition metal carbides, such as WC, have been coated with the monolayer of graphite at high repeatability, to create the surface layer materials. An attempt has been done to produce the halite type structure by substituting Ti as the atom in the outermost layer of TiC by W. The new method, based on the low-speed deuterium ion scattering, has been developed to analyze the surface bonding conditions, clarifying the conditions of alkalis adsorbed on and bonded to metallic surfaces, and their surface reactivities.

Magnetic and magnetothermal studies of iron boride (FeB) nanoparticles

NASA Astrophysics Data System (ADS)

Hamayun, M. Asif; Abramchuk, Mykola; Alnasir, Hisham; Khan, Mohsin; Pak, Chongin; Lenhert, Steven; Ghazanfari, Lida; Shatruk, Michael; Manzoor, Sadia

2018-04-01

We report magnetic and magnetothermal properties of iron boride (FeB) nanoparticles prepared by surfactant-assisted ball milling of arc-melted bulk ingots of this binary alloy. Size-dependent magnetic properties were used to identify the transition to the single domain limit and calculate the anisotropy and exchange stiffness constants for this system. Extended milling is seen to produce coercivity enhancement and exchange bias of up to 270 Ôe at room temperature. The magnetothermal properties were investigated by measuring the response of single domain FeB nanoparticles to externally applied ac magnetic fields. All investigated particle sizes show a significant heating response, demonstrating their potential as candidates for magnetically induced hyperthermia. FeB nanoparticles were encapsulated into lipophilic domains of liposomes as evidenced by TEM. Exposure of HeLa cells to these liposomes did not affect cell viability, suggesting the biocompatibility of these new magnetic nanomaterials.

Properties and utilization of poplar wood

Treesearch

John J. Balatinecz; David E. Kretschmann

2001-01-01

Hybrid poplars are fast-growing, moisture-loving, full-sun-loving large trees that can be a rapid source of wood fiber. With the introduction of waferboard, oriented strandboard (OSB), and laminated strand lumber (LSL), aspen utilization has dramatically increased. Indigenous and hybrid poplars, however, present their own challenges, such as high discoloration...

Mechanical properties of wood-based composite materials

Treesearch

Zhiyong Cai; Robert J. Ross

2010-01-01

The term composite is used to describe any wood material bonded together with adhesives. The current product mix ranges from fiberboard to laminated beams and components. In this chapter, wood-based composite materials are classified into the following categories: panel products (plywood, oriented strandboard (OSB), particleboard, fiberboard, medium-density fiberboard...

Anti-scratch AlMgB14 Gorilla® Glass coating

NASA Astrophysics Data System (ADS)

Putrolaynen, V. V.; Grishin, A. M.; Rigoev, I. V.

2017-10-01

Hard aluminum-magnesium boride (BAM) films were fabricated onto Corning® Gorilla® Glass by radio-frequency magnetron sputtering of a single stoichiometric AlMgB14 target. BAM films exhibit a Vickers hardness from 10 to 30 GPa and a Young's modulus from 80 to 160 GPa depending on applied loading forces. Deposited hard coating increases the critical load at which glass substrate cracks. The adhesion energy of BAM films on Gorilla® Glass is 6.4 J/m2.

First-principles investigation of Cr-doped Fe2B: Structural, mechanical, electronic and magnetic properties

NASA Astrophysics Data System (ADS)

Wei, Xiang; Chen, Zhiguo; Zhong, Jue; Wang, Li; Wang, Yipeng; Shu, Zhongliang

2018-06-01

The structural, mechanical, electronic and magnetic properties of Fe8-xCrxB4 (x = 0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7 and 8) have been investigated by first-principles calculation. It was found that the calculated structural parameters are well consistent with available experimental data. Moreover, all studied compounds are thermodynamically stable phases. On the whole, the moduli of the compounds firstly increase and then decrease with the increase of Cr concentration, whereas the variation of hardness exhibits more fluctuations. All Cr-doped Fe2B have better ductility than Fe2B except Fe2Cr6B4 and Fe5Cr3B4. Interestingly, Fe4Cr4B4 is of not only the slightly larger hardness, but also much better ductility than Fe2B. As the Cr concentration is lower than 20 wt%, the hardness of Cr-doped Fe2B slightly decreases with increasing Cr, whereas the sharply increased hardness of (Fe, Cr)2B in Fe-B alloys or boriding layer should be attributed to the multiple alloying effects resulting from Cr and the other alloying elements. The electronic structures revealed that the Fe-B and/or Cr-B bonds are mainly responsible for their mechanical properties, and the M-N (M = Fe or Cr, N = Fe or Cr) bonds in 〈2 2 0〉 and 〈1 1 3〉 orientations show covalent character. Additionally, the magnetic moments (Ms) of the compounds do not monotonically decrease with increasing Cr.

Magnetic resonance studies of inorganic oxides and a new pulse programming system for pulsed EMR

NASA Astrophysics Data System (ADS)

Schwartz, Dwight Allen

We have investigated several inorganic oxide systems using nuclear and electron magnetic resonance spectroscopies and also report a new pulse programming system for a pulsed S-band EMR spectrometer. We show in a study of simple perovskites (Ca,Sr,Ba)(Ti,Zr) Osb3 that magic-angle spinning O-17 NMR provides unique, highly-resolved spectra in these materials and gives evidence of being useful as a diagnostic tool in mixed phase materials (Asb{x}Asbsp{1-x}{'})BOsb3. Various used NMR and EMR techniques to study of the commercial borosilicate glasses CGW-3320, CGW-7502, CGW-7740 (Pyrex) and GSC-4, and T-08 (pure silica glass) which had received 5-10 gigarad doses of Co-60 gamma-radiation in the presence and absence of hydrogen gas. We show that B-11, Al-27 and Si-29 MAS NMR spectra contain indications of structural changes in these glasses as a result of large doses of radiation. We also observed the reduction of trace Ti(IV) to Ti(III) when Hsb2 gas was present during irradiation of glass samples. Static NMR and EMR studies in the (Na,Li)POsb3 system indicate a possible mixed alkali effect in the spin-lattice relaxation of Na-23 in NaPOsb3 and Lisb{0.4}Nasb{0.6}POsb3. Static Na-23 NMR studies of NaPOsb3 reveal the presence of different structural or dynamical environments as a function of temperatures between 23-566 C. We have investigated glass and glass fibers of Lisb{0.6}Nasb{0.4}POsb3 and Na(Psb{0.99},Vsb{0.01})Osb3, and show P-31 NMR and EMR evidence that these materials remained structurally isotropic when pulled into fibers. We show that vanadium (in Na(Psb{0.99},Vsb{0.01})Osb3) appears to suppress radiolytic unpaired electron and hole defect production which does take place in nominally vanadium-free NaPOsb3 during small doses of gamma-radiation. We describe hardware and software developed for a pulse programming system for a pulsed S-band EMR spectrometer. This system supports user-programmable automatic independent control of all pulse sequence parameters (pulse and delay durations, and pulse phases). We demonstrate the capabilities of this new system in 2-, 3-, and 4-pulse EMR experiments, and also demonstrate a new software suite for interactive simulation and simulation optimization of electron spin echo envelope modulation (ESEEM) patterns using a genetic algorithm.

Application of Spray Foam Insulation Under Plywood and OSB Roof Sheathing (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

2013-11-01

Spray polyurethane foams (SPFs) have advantages over alternative insulation methods because they provide air sealing in complex assemblies, particularly roofs. Spray foam can provide the thermal, air, and vapor control layers in both new and retrofit construction. Unvented roof strategies with open cell and closed cell SPF insulation sprayed to the underside of roof sheathing have been used since the mid-1990s to provide durable and efficient building enclosures. However, there have been isolated incidents of failures (either sheathing rot or SPF delamination) that raise some general concerns about the hygrothermal performance and durability of these systems. The primary risks formore » roof systems are rainwater leaks, condensation from diffusion and air leakage, and built-in construction moisture. This project directly investigated rain and indirectly investigated built-in construction moisture and vapor drives. Research involved both hygrothermal modeling of a range of rain water leakage scenarios and field evaluations of in-service residential roofs. Other variables considered were climate zone, orientation, interior relative humidity, and the vapor permeance of the coating applied to the interior face of open cell SPF.« less

KSC-04PD-1290

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Towers and girders are the current construction components on the Operations Support Building (OSB) II in the Launch Complex 39 Area. The new building, which replaces modular housing constructed more than 20 years ago, will house NASA and contractor support staff for shuttle operations. The new structure is projected to be ready in April 2005.

KSC-04PD-1288

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Another phase of construction is shown on the Operations Support Building (OSB) II in the Launch Complex 39 Area. The new building, which replaces modular housing constructed more than 20 years ago, will house NASA and contractor support staff for shuttle operations. The new structure is projected to be ready in April 2005.

Correlatin between the Officer Selection Battery and the ROTC Basic Camp Student Evaluation Report.

ERIC Educational Resources Information Center

Martin, Clessen J.; Hanser, Lawrence M.

The correlation was examined between the Officer Selection Battery (OSB) and the five areas of evaluation comprising the Army Reserve Officers Training Corps (ROTC) Basic Camp Student Evaluation Report: physical fitness, graded military skills, job performance, peer rating, and academic potential and grades. The moderating effect of the…

KSC-04PD-1291

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Towers and girders are the current construction components on the Operations Support Building (OSB) II in the Launch Complex 39 Area. The new building, which replaces modular housing constructed more than 20 years ago, will house NASA and contractor support staff for shuttle operations. The new structure is projected to be ready in April 2005.

KSC-04PD-1289

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Towers and girders are the current construction components on the Operations Support Building (OSB) II in the Launch Complex 39 Area. The new building, which replaces modular housing constructed more than 20 years ago, will house NASA and contractor support staff for shuttle operations. The new structure is projected to be ready in April 2005.

Development of an Observational Rating Schedule for Preschool Children's Peer-Group Behavior.

ERIC Educational Resources Information Center

Cunningham, Jo Lynn; Boger, Robert P.

The feasiblity of an observational rating scale which would provide objective, reliable and quantifiable measures of social and affective behavior was investigated. The Observation of Socialization Behavior (OSB), focusing on peer-group behavior of pre-school children and designed for use in unstructured situations was developed. Two forms of the…

Building Essential Skills for the Ohio Building and Construction Industry. Final Report.

ERIC Educational Resources Information Center

Pritz, Sandra G.; And Others

The Center on Education and Training for Employment (CETE) at the Ohio State University worked in partnership with the Ohio State Building and Construction Trades Council (OSB&CT) to develop and deliver customized workplace literacy services for local union members in six major Ohio cities (Columbus, Cleveland, Cincinnati, Toledo, Dayton, and…

Selective Iterative Waterfilling for Digital Subscriber Lines

NASA Astrophysics Data System (ADS)

Xu, Yang; Le-Ngoc, Tho; Panigrahi, Saswat

2007-12-01

This paper presents a high-performance, low-complexity, quasi-distributed dynamic spectrum management (DSM) algorithm suitable for DSL systems. We analytically demonstrate that the rate degradation of the distributed iterative waterfilling (IW) algorithm in near-far scenarios is caused by the insufficient utilization of all available frequency and power resources due to its nature of noncooperative game theoretic formulation. Inspired by this observation, we propose the selective IW (SIW) algorithm that can considerably alleviate the performance degradation of IW by applying IW selectively to different groups of users over different frequency bands so that all the available resources can be fully utilized. For [InlineEquation not available: see fulltext.] users, the proposed SIW algorithm needs at most [InlineEquation not available: see fulltext.] times the complexity of the IW algorithm, and is much simpler than the centralized optimal spectrum balancing (OSB), while it can offer a rate performance much better than that of the IW and close to the maximum possible rate region computed by the OSB in realistic near-far DSL scenarios. Furthermore, its predominantly distributed structure makes it suitable for DSL implementation.

Differences in accuracy and underestimation rates for 14- versus 16-gauge core needle biopsies in ultrasound-detectable breast lesions.

PubMed

Lai, Hung-Wen; Wu, Hwa-Koon; Kuo, Shou-Jen; Chen, Shou-Tung; Tseng, Hsin-Shun; Tseng, Ling-Ming; Chen, Dar-Ren

2013-04-01

Core needle biopsy (CNB) was widely used in the diagnosis of ultrasound-detectable breast lesions. We aimed at assessing the diagnostic performance differences between 14- and 16-gauge ultrasound-guided core biopsies. This retrospective study enrolled patients receiving CNB from January 2001 to December 2007. The results of 14- and 16-gauge breast CNBs were compared with pathology reports of open surgical biopsy (OSB). A total of 1024 paired CNB and OSB results were obtained from 1732 CNB procedures in 1630 patients.Those CNB results reached 92.9% sensitivity, 99.7% specificity, 5.96% underestimation, and 94.8% accuracy rates. There was no difference in sensitivity (p=0.17) or specificity (p=0.38) between 14- and 16-gauge needles. However, better overall accuracy (p=0.02), less underestimation (p<0.001), and lower false-negative (p=0.02) rates were found for the 14-gauge CNB. Regarding accuracy and underestimation rates, a 14-gauge needle is preferred to a 16-gauge one in ultrasound-guided biopsies. Copyright © 2012. Published by Elsevier B.V.

First-principles study on the structure, elastic properties, hardness and electronic structure of TMB4 (TM=Cr, Re, Ru and Os) compounds

NASA Astrophysics Data System (ADS)

Pan, Y.; Zheng, W. T.; Guan, W. M.; Zhang, K. H.; Fan, X. F.

2013-11-01

The structural formation, elastic properties, hardness and electronic structure of TMB4 (TM=Cr, Re, Ru and Os) compounds are investigated using first-principles approach. The value of C22 for these compounds is almost two times bigger than the C11 and C33. The intrinsic hardness, shear modulus and Young's modulus are calculated to be in a sequence of CrB4>ReB4>RuB4>OsB4, and the Poisson's ratio and B/G ratio of TMB4 follow the order of CrB4

Object Detection for Agricultural and Construction Environments Using an Ultrasonic Sensor.

PubMed

Dvorak, J S; Stone, M L; Self, K P

2016-04-01

This study tested an ultrasonic sensor's ability to detect several objects commonly encountered in outdoor agricultural or construction environments: a water jug, a sheet of oriented strand board (OSB), a metalfence post, a human model, a wooden fence post, a Dracaena plant, a juniper plant, and a dog model. Tests were performed with each target object at distances from 0.01 to 3 m. Five tests were performed with each object at each location, and the sensor's ability to detect the object during each test was categorized as "undetected," "intermittent," "incorrect distance," or "good." Rigid objects that presented a larger surface area to the sensor, such as the water jug and OSB, were better detected than objects with a softer surface texture, which were occasionally not detected as the distance approached 3 m. Objects with extremely soft surface texture, such as the dog model, could be undetected at almost any distance from the sensor. The results of this testing should help designers offuture systems for outdoor environments, as the target objects tested can be found in nearly any agricultural or construction environment.

In-situ Formation of Reinforcement Phases in Ultra High Temperature Ceramic Composites

NASA Technical Reports Server (NTRS)

Stackpoole, Margaret M (Inventor); Gasch, Matthew J (Inventor); Olson, Michael W (Inventor); Hamby, Ian W. (Inventor); Johnson, Sylvia M (Inventor)

2013-01-01

A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB.sub.2, ZrB.sub.2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.

Precise time-window for the onset of glacial termination found

NASA Astrophysics Data System (ADS)

Lai, C.-C.; Tseng, Y.-H.; Dietrich, D. E.

2009-04-01

Following a set of three simple rules, we have found a precise time-window (TW) for each onset of a glacial termination (GT) appeared during the last million years. The onset of GT (OGT) is defined as the year when the following two conditions are met: (1) the benthic delta 18-O is a maximum and greater than 4.5‰ and (2) its value continually drops 1‰ within 5 Ky. We developed the rules based on three hypotheses. We hypothesize that: (H1) The Earth's three orbital parameters (eccentricity, obliquity and precession of equinox) determine the insolation which is the key force to the climate system. (H2) However, only a small fraction of insolation is converted into sensible heat (SH) and chemical energy through photosynthesis (CETP) as influxes to the climate system's main heat capacitors (HCs), namely the world oceans. When insolation increases, both the SH flux and CETP increase. The downward SH flux will only increase the stability of the seawater. Nonetheless, the CETP gets accumulated faster than average. The CETP cascades through the marine food web and bacterial degradation. Finally, it is stored in the simple gas molecules (such as CH4) that form methane hydrate (MH) and other hydrates such as hydrogen sulfide hydrate (HSH) in deep sea sediments after a long time. While hydrates deposit accumulates with time, it also breaks off from the sediments from time to time. Since the density of MH is slightly smaller than average seawater, the MH ascends slowly from deep sea into upper part of ocean. But, HSH is slightly denser than the warm seawater in the upper part of ocean. Over the portion of glacial cycle when insolation is strong, the existence of a residual SH prevents the ascension of hydrates. (H3) Internal forcing - An internal energy converter or a heat generator exists in the oceans. Lai (2007) has found the link between the observed seawater warming at intermediate depth (400 - 750 m) (Barnett et al. 2001) and the dissociation of floating microscopic MH and subsequent methane oxidation via bacteria. We postulate that the cooling of deep seawater when the insolation is weak leads to more hydrates ascending through seawater to the level for dissociation (which is a process depending on seawater temperature and pressure). The oxidation of CH4 and H2S after hydrate-dissociation is a multi-step process/phenomenon that we refer to as ocean slow-burn (OSB). It generates the maximum heat per mole of atom-C among all carbon-containing compounds, including sugars. Through oxidation, the CETP is now released as heat that is transferred via biomass, eventually being deposited into the seawater. Since the heat generated in the OSB is greater than that required to dissociate hydrates, they become self-sustained and run-away as long as all players (MH, bacteria, and methane ice worms (Fisher et al. 2000)) are present. So, the glacial termination is a process to release the stored CETP instead of trapping more insolation energy. (H4) Having accumulated enough energy sources, the OGT will happen when the joint effect of the three parameters triggers the discharge of the HCs. The trigger is an abrupt reduction in insolation over the Southern Oceans, especially South Atlantic under which lies the active Mid-Atlantic Ridge. The three rules were found through following steps: (1) finding a wide time-window (WTW) within which the energy (stored in hydrates) required to sustain a GT can be accumulated. (2) Then, we find a narrow time-window (NTW) (within that WTW) when the HC is abruptly cooled down due to a quick reduction in insolation. That NTW shall be the ideal time for the OGT. The variation of eccentricity is the factor controlling the annual global integral of insolation (AGII). The bigger the eccentricity the greater the AGII is. The greater the AGII the more the global CETP capture is. Presume that eccentricity varies like a sinusoidal function of time with a single period of 95 Ky. Then, the CETP being stored into the HCs varies in the same cycle, too. On the other hand, the hydrates are being consumed by OSB process at a rate, (namely r(OSB)), that is not directly controlled by the eccentricity. Assume that during the glacial period r(OSB) is significant but smaller than the accumulation rate of CETP (namely, r(CETP)). This leads us to think that during the phase -90o to 90o (valley to peak) half cycle is a better WTW to accumulate hydrates than the 90o to 270o (peak to valley) half cycle. This is Rule 1. The NTW is regulated by Rules 2 and 3. Rule 2 is that the obliquity must be increasing. Rule 3 is that precession must be near 180o phase angle. The reasons for these two rules will be explained. The NTW will be shown to match every OGT appeared in last one million years.

KSC-2011-1342

NASA Image and Video Library

2011-02-02

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, KSC firefighters were on the scene after a backhoe inadvertently struck a natural gas line at around 8:40 a.m. EST in the area north of the Multi Function Facility (MFF). As a precaution, personnel were evacuated from Orbiter Processing Facilities 1 and 2, the MFF, Processing Control Center and Operations Support Building (OSB) I. All traffic was blocked on the Saturn Causeway near the facilities. There were no injuries or damage to any facilities and personnel were allowed back into their buildings before mid-day and the roadway open to traffic. Photo credit: NASA/Jack Pfaller

Intracranial translucency assessment at first trimester nuchal translucency ultrasound.

PubMed

Lane, Annah; Lee, Ling; Traves, Donna; Lee, Andreas

2017-04-01

The antenatal diagnosis of open spina bifida (OSB), a neural tube defect, is predominantly made at the second trimester morphology scan by ultrasound detection of structural abnormalities resulting from the associated Chiari II malformation. Evidence has emerged suggesting that these structural abnormalities can be detected earlier, by examination of the posterior fossa as part of the first trimester nuchal translucency scan. In particular, absence of the intra-cranial translucency (IT) of the fourth ventricle has shown promise as a diagnostic marker of OSB, although the sensitivity and specificity of this finding varies widely in the literature. The aim of this study is to assess the feasibility of obtaining the image of the IT at our institution as part of the routine first trimester scan. This is a prospective study of 900 obstetric patients who presented to a tertiary women's imaging centre for routine first trimester nuchal translucency screening ultrasound for the year 2014. Their risk status was that of the general population (low risk) prior to presentation. A total of 158 patients were excluded, leaving a study group of 742. Sonographers obtained a mid-sagittal view of the fetal face with particular focus on optimum viewing of the IT. All images were examined by a Radiology Registrar for presence or absence of IT. Duration of each scan was documented. The IT image was successfully acquired in 94.9% of scans. Maternal pre-pregnancy BMI and fetal lie were shown to have a statistically significant effect on success of acquisition of the IT image. No cases of OSB were diagnosed during the study. Scan times were not lengthened by the addition of the image. We consider that acquisition of an image of the IT as part of the routine first trimester nuchal translucency scan is feasible, without lengthening appointment times. © 2016 The Royal Australian and New Zealand College of Radiologists.

Full-Scale Experimental Investigation to Quantify Building Component Ignition Vulnerability from Mulch Beds Attacked by Firebrand Showers.

PubMed

Manzello, Samuel L; Suzuki, Sayaka; Nii, Daisaku

2017-03-01

Structure ignition by wind-driven firebrand showers is an important fire spread mechanism in large outdoor fires. Experiments were conducted with three common mulch types (shredded hardwood mulch, Japanese Cypress wood chips, and pine bark nuggets) placed adjacent to realistic-scale reentrant corners. In the first series of experiments, mulch beds were placed adjacent to a re-entrant corner constructed with wood studs and lined with oriented strand board (OSB) as the sheathing. The premise behind conducting experiments with no siding treatments applied was predicated on the notion that bare OSB mulch contact would be a worst-case scenario, and therefore, a wall assembly in the most vulnerable state to mulch ignition. In the second series of experiments, vinyl siding was applied to the re-entrant corner assemblies (wood studs/OSB/moisture barrier/vinyl siding), and the influence of vertical separation distance (102 mm or 203 mm) on wall ignition from adjacent mulch beds was determined. The vertical separation distance was maintained by applying gypsum board to the base of the re-entrant corner. The siding itself did not influence the ignition process for the mulch beds, as the mulch beds were the first to ignite from the firebrand showers. In all experiments, it was observed that firebrands produced smoldering ignition in the mulch beds, this transitioned to flaming ignition, and the re-entrant corner assembly was exposed to the flaming mulch beds. With no siding treatments applied, the flaming mulch beds ignited the re-entrant corner, and ignition was observed to propagate to the back side of re-entrant corner assembly under all wind speeds (6 m/s to 8 m/s). With respect to the re-entrant corners fitted with vinyl siding, the mulch type, vertical separation distance, and wind speed were important parameters as to whether flaming ignition was observed to propagate to the back-side of a reentrant corner assembly. Mulches clearly pose an ignition hazard to structures in large outdoor fires.

Flying Under the LiDAR: Relating Forest Structure to Bat Community Diversity

NASA Astrophysics Data System (ADS)

Swanson, A. C.; Weishampel, J. F.

2015-12-01

Bats are important to many ecological processes such as pollination, insect (and by proxy, disease) control, and seed dispersal and can be used to monitor ecosystem health. However, they are facing unprecedented extinction risks from habitat degradation as well as pressures from pathogens (e.g., white-nose syndrome) and wind turbines. LiDAR allows ecologists to measure structural variables of forested landscapes with increased precision and accuracy at broader spatial scales than previously possible. This study used airborne LiDAR to classify forest habitat/canopy structure at the Ordway-Swisher Biological Station (OSBS) in north central Florida. LiDAR data were acquired by the NEON airborne observation platform in summer 2014. OSBS consists of open-canopy pine savannas, closed-canopy hardwood hammocks, and seasonally wet prairies. Multiple forest structural parameters (e.g., mean, maximum, and standard deviation of height returns) were derived from LiDAR point clouds using the USDA software program FUSION. K-means clustering was used to segregate each 5x5 m raster across the ~3765 ha OSBS area into six different clusters based on the derived canopy metrics. Cluster averages for maximum, mean, and standard deviation of return heights ranged from 0 to 19.4 m, 0 to 15.3 m, and 0 to 3.0 m, respectively. To determine the relationships among these landscape-canopy features and bat species diversity and abundances, AnaBat II bat detectors were deployed from May to September in 2015 stratified by these distinct clusters. Bat calls were recorded from sunset to sunrise during each sampling period. Species were identified using AnalookW. A statistical regression model selection approach was performed in order to evaluate how forest attributes such as understory clutter, open regions, open and closed canopy, etc. influence bat communities. This knowledge provides a deeper understanding of habitat-species interactions to better manage survival of these species.

Remote Sensing of Vegetation Species Diversity: The Utility of Integrated Airborne Hyperspectral and Lidar Data

NASA Astrophysics Data System (ADS)

Krause, Keith Stuart

The change, reduction, or extinction of species is a major issue currently facing the Earth. Efforts are underway to measure, monitor, and protect habitats that contain high species diversity. Remote sensing technology shows extreme value for monitoring species diversity by mapping ecosystems and using those land cover maps or other derived data as proxies to species number and distribution. The National Ecological Observatory Network (NEON) Airborne Observation Platform (AOP) consists of remote sensing instruments such as an imaging spectrometer, a full-waveform lidar, and a high-resolution color camera. AOP collected data over the Ordway-Swisher Biological Station (OSBS) in May 2014. A majority of the OSBS site is covered by the Sandhill ecosystem, which contains a very high diversity of vegetation species and is a native habitat for several threatened fauna species. The research presented here investigates ways to analyze the AOP data to map ecosystems at the OSBS site. The research attempts to leverage the high spatial resolution data and study the variability of the data within a ground plot scale along with integrating data from the different sensors. Mathematical features are derived from the data and brought into a decision tree classification algorithm (rpart), in order to create an ecosystem map for the site. The hyperspectral and lidar features serve as proxies for chemical, functional, and structural differences in the vegetation types for each of the ecosystems. K-folds cross validation shows a training accuracy of 91%, a validation accuracy of 78%, and a 66% accuracy using independent ground validation. The results presented here represent an important contribution to utilizing integrated hyperspectral and lidar remote sensing data for ecosystem mapping, by relating the spatial variability of the data within a ground plot scale to a collection of vegetation types that make up a given ecosystem.

Transition metal substitutions for Cu in BSCCO: An instructive probe of high temperature superconductivity

NASA Astrophysics Data System (ADS)

Schneider, Clinton W.

1998-12-01

Single crystals of the high temperature superconductor Bisb2Srsb2Casb1(Cusb{1-x}Msb{x})sb2)Osb{8+delta} have been grown for M = Zn, Ni, Co, Fe, and Pd in order to probe the effect of transition metal impurities on superconducting properties. Samples have been characterized by XRD, electron microprobe, and transport measurements. Measurement of resistance is used to determine the depression of Tsb{c} due to the impurities. We determine a value dTsb{c}/dx = -7.8K/at/for all substituents, independent of magnetic moment. Considered in terms of the Abrikosov-Gorkov theory for impurity scattering in superconductors, this result agrees with a d-wave order parameter and strong coupling.

Status and trends : profile of structural panels in the United States and Canada

Treesearch

Henry Spelter; David McKeever; Matthew Alderman

2006-01-01

This paper provides an overview of the North American (United States and Canada) structural panel industry, which consists of softwood plywood and oriented strandboard (OSB). The paper describes the evolution of overall capacities, effective capacity utilization, and manufacturing costs. As part of that, it describes changes in industry operating parameters such as...

Moisture Performance of Energy-Efficient and Conventional Wood-Frame Wall Assemblies in a Mixed-Humid Climate

Treesearch

Samuel Glass; Vladimir Kochkin; S. Drumheller; Lance Barta

2015-01-01

Long-term moisture performance is a critical consideration for design and construction of building envelopes in energy-efficient buildings, yet field measurements of moisture characteristics for highly insulated wood-frame walls in mixed-humid climates are lacking. Temperature, relative humidity, and moisture content of wood framing and oriented strand board (OSB)...

DOE Zero Energy Ready Home Case Study: Caldwell and Johnson, Exeter, Rhode Island

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

This house, constructed by Caldwell and Johnson, should save its owners $600 per year over the 2009 IECC with the help of efficiency measures such as walls with OSB sheathing and R-13 open cell spray foam insulation. The home garnered a 2013 Housing Innovation Award in the custom builder category.

The Impact of Denominational Affiliation on Organizational Sense of Belonging and Commitment of Adjunct Faculty at Bible Colleges and Universities

ERIC Educational Resources Information Center

Pilieci, Kimberly M.

2016-01-01

The majority of faculty in higher education, including secular and biblical institutions, are adjunct faculty. The literature suggests that adjunct faculty are less effective and satisfied, and have weaker organizational sense of belonging (OSB) and affective organizational commitment (AOC). Denominational affiliation (DA) and religious commitment…

Hygrothermal Anaylsis of Wood-Frame Wall Assemblies in a Mixed-Humid Climate

Treesearch

Samuel V. Glass

2013-01-01

This study uses a one-dimensional hygrothermal model to investigate the moisture performance of 10 residential wood-frame wall assemblies in a representative mixed-humid climate location of Baltimore, Maryland (climate zone 4A). All the assemblies include oriented strandboard (OSB) sheathing and vinyl siding. The walls differ in stud cavity thickness, level of cavity...

Physical, mechanical, and fire properties of oriented strandboard with fire retardant treated veneers

Treesearch

Nadir Ayrilmis; Zeki Candan; Robert White

2007-01-01

This study evaluated physical, mechanical and fire properties of oriented strand boards (OSB) covered with fire retardant treated veneers. The beech (Fagus orientalis Lipsky) veneers were treated with either monoammonium phosphate, diammonium phosphate, lime water or a borax/boric acid (1 : 1 by weight) mixture. Physical and mechanical properties of the specimens were...

Thermodynamic analysis of chemical compatibility of several reinforcement materials with niobium aluminides

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1989-01-01

Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

Ultra-hard AlMgB14 coatings fabricated by RF magnetron sputtering from a stoichiometric target

NASA Astrophysics Data System (ADS)

Grishin, A. M.; Khartsev, S. I.; Böhlmark, J.; Ahlgren, M.

2015-01-01

For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 μm thick film.

Formation and characterization of asymmetric polyimide hollow fiber membranes for gas separations

NASA Astrophysics Data System (ADS)

Clausi, Dominic Thomas

Ultra-thin and virtually defect-free polyimide hollow fiber membranes were formed using a "dry/wet" type spinning solution. Fibers were spun from the commercially available polyimide, Matrimidsp{°ler}, using a dry-jet, wet quench spinning apparatus. Spin dopes were comprised of volatile and non-volatile solvents, polymer, and non-solvent. The influence of dope composition, spinning parameters, and dehydration procedures on the membrane morphology and performance was investigated. Without post-treatment, the fibers exhibited skin thicknesses less than 1000 A and Osb2/Nsb2 selectivities within 90% of those determined for dense, solution-cast films. The 250 mum O.D./125 mum I.D. fibers were spun at take-up rates comparable to those used in commercial processes and had macrovoid-free morphologies. A new characterization technique has also been developed where a permeating gas is held at constant transmembrane pressure while the average pressure in the porous support of an asymmetric membrane is varied. This alters the mean free path of gas molecules permeating through the substructure while maintaining a constant driving force for permeation. This technique characterizes the magnitude of the substructure resistance and its pressure dependence, thereby providing a means to compare the morphologies of different membrane samples. Well defined composite-laminate membranes were constructed to validate this technique, which was subsequently used to characterize the substructures of the hollow fiber membranes formed in this work. Two additional rapid characterization techniques have been developed for use before fiber dehydration (i.e., wet fibers). These techniques probe the membrane skin layer with aqueous solutions of disperse dyes and poly(ethylene glycol), respectively. Fiber skin integrity can be characterized using these techniques prior to lengthy downstream processing (i.e., solvent exchange, drying, and post-treatment), providing quick elucidation of membrane skin morphology. Finally, a qualitative model describing the skin layer morphology of phase inversion membranes has been developed. This model arose from observed differences in the permeation characteristics of highly sorbing gases between bore and shell side feeds. It is proposed that the skin layer contains an asymmetric distribution of unrelaxed volume introduced during the formation process. This model has been successfully tested with COsb2/CHsb4 permeation measurements conducted at varying temperatures and feed configurations.

Processing development of 4 tantalum carbide-hafnium carbide and related carbides and borides for extreme environments

NASA Astrophysics Data System (ADS)

Gaballa, Osama Gaballa Bahig

Carbides, nitrides, and borides ceramics are of interest for many applications because of their high melting temperatures and good mechanical properties. Wear-resistant coatings are among the most important applications for these materials. Materials with high wear resistance and high melting temperatures have the potential to produce coatings that resist degradation when subjected to high temperatures and high contact stresses. Among the carbides, Al4SiC4 is a low density (3.03 g/cm3), high melting temperature (>2000°C) compound, characterized by superior oxidation resistance, and high compressive strength. These desirable properties motivated this investigation to (1) obtain high-density Al4SiC4 at lower sintering temperatures by hot pressing, and (2) to enhance its mechanical properties by adding WC and TiC to the Al4SiC4. Also among the carbides, tantalum carbide and hafnium carbide have outstanding hardness; high melting points (3880°C and 3890°C respectively); good resistance to chemical attack, thermal shock, and oxidation; and excellent electronic conductivity. Tantalum hafnium carbide (Ta4HfC 5) is a 4-to-1 ratio of TaC to HfC with an extremely high melting point of 4215 K (3942°C), which is the highest melting point of all currently known compounds. Due to the properties of these carbides, they are considered candidates for extremely high-temperature applications such as rocket nozzles and scramjet components, where the operating temperatures can exceed 3000°C. Sintering bulk components comprised of these carbides is difficult, since sintering typically occurs above 50% of the melting point. Thus, Ta4 HfC5 is difficult to sinter in conventional furnaces or hot presses; furnaces designed for very high temperatures are expensive to purchase and operate. Our research attempted to sinter Ta4HfC5 in a hot press at relatively low temperature by reducing powder particle size and optimizing the powder-handling atmosphere, milling conditions, sintering temperature, and hot-pressing pressure. Also, WC additions to Ta4HfC5 were found to improve densification and increase microhardness. The ability to process these materials at relatively low temperature would save energy and reduce cost. Boron-based hard materials are used in numerous applications such as industrial machining, armor plating, and wear-resistant coatings. It was often thought that in addition to strong bonding, super-hard materials must also possess simple crystallographic unit cells with high symmetry and a minimum number of crystal defects (e.g., diamond and cubic boron nitride (cBN)). However, one ternary boride, AlMgB14, deviates from this paradigm; AlMgB 14 has a large, orthorhombic unit cell (oI64) with multiple icosahedral boron units. TiB2 has been shown to be an effective reinforcing phase in AlMgB 14, raising hardness, wear resistance, and corrosion resistance. Thus, it was thought that adding other, similar phases (i.e., ZrB2 and HfB2) to AlMgB14 could lead to useful improvements in properties vis-à-vis pure AlMgB14. Group IV metal diborides (XB2, where X = Ti, Zr, or Hf) are hard, ultra-high temperature ceramics. These compounds have a primitive hexagonal crystal structure (hP3) with planes of graphite-like boride rings above and below planes of metal atoms. Unlike graphite, there is strong bonding between the planes, resulting in high hardness. For this study two-phase composites of 60 vol. % metal diborides with 40 vol. % AlMgB14 were produced and characterized.

The Nature of the Microstructure and Interface Boundary Formation in Directionally Solidified Ceramic Boride Composites

DTIC Science & Technology

2011-05-01

failure resistance, which results from their different microplasticity (microbrittleness) and relaxation ability. In order to evaluate the... microplasticity (microbrittleness) in the series of isomorphic hexaborides produced by zone melting we have plotted a number of statistical curves that show

Ultracapacitor current collector

DOEpatents

Jerabek, Elihu Calfin; Mikkor, Mati

2001-10-16

An ultracapacitor having two solid, nonporous current collectors, two porous electrodes separating the collectors, a porous separator between the electrodes and an electrolyte occupying the pores in the electrodes and separator. At least one of the current collectors comprises a conductive metal substrate coated with a metal nitride, carbide or boride coating.

Formation and characterization of mullite fibers produced by inviscid melt-spinning

NASA Astrophysics Data System (ADS)

Xiao, Zhijun

IMS is a technique used to form fibers from low viscosity melts by means of stream stabilization in a reactant gas, in this case propane. Mullite (3Alsb2Osb3*2SiOsb2) was selected as the material to be fiberized. A stable mullite melt was obtained at 2000sp°C. Some short fibers and shot were formed in the fiber forming experiments. Crucible material selection is a prerequisite for proper application of the IMS technique. The effect of two crucible materials-graphite and boron nitride were studied. A carbothermal reaction occurred between the mullite melt and the graphite crucible. Boron nitride was selected as the crucible material because a relatively stable melt could be obtained. Operating environment is another factor that affects IMS mullite fiber formation. The effects of vacuum, nitrogen and argon on mullite melting behavior were studied. Argon gas was selected as the operating environment. A 2sp3 factorial design was developed to study the effect of such variables as temperature, holding time at the temperature, and heating rate on mullite melting behavior. The effects of the variables and interactions were calculated. Temperature has the biggest positive effect, holding time is the second, heating rate just has a very small negative effect. A detailed investigation of the mullite decomposition mechanism and kinetics was conducted in this work. A solid reaction mechanism was proposed. The kinetic results and IR analysis support the proposed mechanism. The carbon source inside the furnace led to the decomposition of mullite. A feasible experimental technique was developed to prevent the decomposition of mullite. The experiments with this design completely controlled the mullite decomposition. The short fibers, shot and some side products formed in the fiber forming experiments were characterized using XRD, XRF and SEM-EDS. The composition of the short fiber and shot was in the range of mullite composition. XRD showed that the diffraction pattern of shot is that of mullite.

RESEARCH ON PHYSICAL AND CHEMICAL PRINCIPLES AFFECTING HIGH TEMPERATURE MATERIALS FOR ROCKET NOZZLES. Quarterly Progress Report, April 1, 1963-June 30, 1963

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowrie, R.

1963-10-31

The development and properties of refractory materials are described. Corrosion of zirconium carbide, niobium carbide, and niobium carbide-zirconium carbide systems by carbon dioxide and hydrochloric acid at 2250 deg C is reported. Corrosion of silver-tungsten alloys by carbon dioxide and oxygen at 2150 to 2440 deg K is summarized. Measurements of pyrolytic and ZTA graphite corrosion by carbon dioxide and oxygen at 2100 to 2800 deg K are shown. At 2300 deg C the rate of formation of methane from graphite and hydrogen is greatly reduced by the addition of helium, at constant hydrogen pressure. Up to 2000 deg Cmore » the effect of helium is small. The pyrolysis of methane on graphite at 2000 deg C is tabulated. Oxidation of tungsten to form WO/sub 2/ and WO/sub 3/ is reported. Vaporization of hafnium borides at 2297 to 2538 deg K is analyzed. The lattice parameters of ZrB/sub 2/ at of TiN/sub 0.6/ and TiN/sub 0.75/ are discussed. Powder metallurgical techniques are used to prepare TiB/sub 2/, ZrB/sub 2/, HfB/ sub 2/, NbB/sub 2/, a nd TaB/sub 2/ for detailed x-ray characterization. The electric conductivity of NbC-ZrC systems is reported. General descriptions are given of analytical techniques for free carbon in carbides and spectrographic methods for metallic impurities in carbides and borides. Preliminary roomtemperature measurements are reported of the elastic properties of polycrystalline ZrB/sub 2/. Titanium carbide is brazed to tungsten with a platinum-boron system. A largegrained polycrystalline specimen of ZrC is plastically deformed in creep at 2134 deg C. Metallographic and x-ray examinations of polycrystalline TiC specimens deformed in creep reveal an increasing development with deformation of subgrains having preferred orientation. (N.W.R.)« less

The Bony Side of Endothelial Cells in Prostate Cancer.

PubMed

Peng, Jia; Kang, Yibin

2017-06-05

Prostate cancer bone metastases are primarily osteoblastic, but the source of bone-forming cells in these lesions remains poorly defined. In this issue of Developmental Cell, Lin et al. (2017) demonstrate that tumor-associated endothelial cells can give rise to osteoblasts in prostate cancer through endothelial-to-osteoblast (EC-to-OSB) conversion. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of resin variables on the creep behavior of high density hardwood composite panels

Treesearch

R.C. Tang; Jianhua Pu; C.Y Hse

1993-01-01

The flexural creep behavior of oriented strandboards (OSB) fabricated with mixed high, density hardwood flakes was investigated. Three types of adhesives, liquid phenolic-formaldehyde (LPF), melamine modified urea-formaldehyde (MUF), and LPF (face)/MUF (core) were chosen in this investigation. The resin contents (RC) used were 3.5 percent and 5.0 percent. The flakes...

Economic feasibility of products from inland West small-diameter timber

Treesearch

Spelter Henry; Rong Wang; Peter Ince

1996-01-01

A large part of the forests located in the Rocky Mountain region of the U.S. West (inland West) is characterized by densely packed, small-diameter stands. The purpose of this study was to examine the economic feasibility of using small-diameter material from this resource to manufacture various wood products: oriented strandboard (OSB), stud lumber, random-length...

Physical and mechanical properties and fire, decay, and termite resistance of treated oriented strandboard

Treesearch

Nadir Ayrilmis; S Nami Kartal; Theodore L. Laufenberg; Jerrold E. Winandy; Robert H. White

2005-01-01

This study evaluated the effects of a number of chemicals on the physical and mechanical properties and fire, decay, and termite resistance of oriented strandboard (OSB) panels. Disodium octaborate tetrahydrate (DOT), boric acid (BA), melamine phosphate (MP), and a BA/DOT mixture were sprayed onto the furnish at varying concentrations. The panels were tested for...

Improving strand quality of upland oaks for use in oriented strand board

Treesearch

David B. DeValliance; Jody D. Gray; Shawn T. Grushecky

2013-01-01

Past research estimates that more than 1 million tons of oak logging residues go unused in West Virginia each year. Much research has been done investigating potential products and markets for this underutilized resource. West Virginia is home to an oriented strand board (OSB) producer that consumes large volumes of small diameter, low quality round wood. However, the...

The complex metal-rich boride Ti1+xRh2-x+yIr3-yB3 (x=0.68, y=1.06) with a new structure type containing B4 zigzag fragments: Synthesis, crystal chemistry and theoretical calculations

NASA Astrophysics Data System (ADS)

Goerens, Christian; Fokwa, Boniface P. T.

2012-08-01

Polycrystalline samples and single crystals of the new complex boride Ti1+xRh2-x+yIr3-yB3 (x=0.68; y=1.06) were synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere and characterized by X-Ray diffraction as well as EDX measurements. The crystal structure was refined on the basis of single crystal data. The new phase, which represents a new structure type containing trans zigzag B4 fragments as well as isolated boron atoms crystallizes in the orthorhombic space group Pbam (Nr. 55) with the lattice parameters a=8.620(1) Å, b=14.995(2) Å and c=3.234(1) Å. First-principles density functional theory calculations using the Vienna ab-initio simulation package (VASP) were performed on an appropriate structural model (using a supercell approach) and the experimental crystallographic data could be reproduced accurately. Based on this model, the density of states and crystal orbital Hamilton population (for bonding analysis) were calculated, using the linear muffin-tin orbital atomic sphere approximation (LMTO-ASA) method. According to these calculations, this metal-rich compound should be metallic, as expected. Furthermore, very strong boron-boron interactions are observed in the trans zigzag B4 fragment, which induce a clear differentiation of two types of metal-boron contacts with different strength. The observed three-dimensional metal-metal interaction is in good agreement with the predicted metallic behavior.

The Spectrum Analysis Solution (SAS) System: Theoretical Analysis, Hardware Design and Implementation.

PubMed

Narayanan, Ram M; Pooler, Richard K; Martone, Anthony F; Gallagher, Kyle A; Sherbondy, Kelly D

2018-02-22

This paper describes a multichannel super-heterodyne signal analyzer, called the Spectrum Analysis Solution (SAS), which performs multi-purpose spectrum sensing to support spectrally adaptive and cognitive radar applications. The SAS operates from ultrahigh frequency (UHF) to the S-band and features a wideband channel with eight narrowband channels. The wideband channel acts as a monitoring channel that can be used to tune the instantaneous band of the narrowband channels to areas of interest in the spectrum. The data collected from the SAS has been utilized to develop spectrum sensing algorithms for the budding field of spectrum sharing (SS) radar. Bandwidth (BW), average total power, percent occupancy (PO), signal-to-interference-plus-noise ratio (SINR), and power spectral entropy (PSE) have been examined as metrics for the characterization of the spectrum. These metrics are utilized to determine a contiguous optimal sub-band (OSB) for a SS radar transmission in a given spectrum for different modalities. Three OSB algorithms are presented and evaluated: the spectrum sensing multi objective (SS-MO), the spectrum sensing with brute force PSE (SS-BFE), and the spectrum sensing multi-objective with brute force PSE (SS-MO-BFE).

Firebrand Production from Building Components Fitted with Siding Treatments

PubMed Central

Suzuki, Sayaka; Manzello, Samuel L.

2016-01-01

Firebrand production from real-scale building components under well-controlled laboratory conditions was investigated. Re-entrant corner assemblies were ignited and during the combustion process, firebrands were collected to determine the size/mass distribution generated from such real-scale building components under varying wind speed. In prior work, a unique ignition methodology was developed to generate firebrands from re-entrant corner assemblies constructed of wood studs and oriented strand board (OSB). In this study, this ignition methodology was applied to re-entrant corners constructed from wood studs/OSB but fitted with actual siding treatments (tar paper and cedar siding) to determine the influence of siding treatments on firebrand generation from wall assemblies. Firebrands were collected with pans filled with water, and then the size and mass of firebrands were measured after drying. The size and mass distributions of firebrands collected in this study were compared with the data from prior component tests as well as the limited studies available in the literature on this topic. Some firebrands were found to be lighter for a given projected area than others, likely produced from cedar siding or tar paper. The effects of applied siding treatments on firebrand production are discussed in detail. PMID:27114643

Firebrand Production from Building Components Fitted with Siding Treatments.

PubMed

Suzuki, Sayaka; Manzello, Samuel L

2016-02-01

Firebrand production from real-scale building components under well-controlled laboratory conditions was investigated. Re-entrant corner assemblies were ignited and during the combustion process, firebrands were collected to determine the size/mass distribution generated from such real-scale building components under varying wind speed. In prior work, a unique ignition methodology was developed to generate firebrands from re-entrant corner assemblies constructed of wood studs and oriented strand board (OSB). In this study, this ignition methodology was applied to re-entrant corners constructed from wood studs/OSB but fitted with actual siding treatments (tar paper and cedar siding) to determine the influence of siding treatments on firebrand generation from wall assemblies. Firebrands were collected with pans filled with water, and then the size and mass of firebrands were measured after drying. The size and mass distributions of firebrands collected in this study were compared with the data from prior component tests as well as the limited studies available in the literature on this topic. Some firebrands were found to be lighter for a given projected area than others, likely produced from cedar siding or tar paper. The effects of applied siding treatments on firebrand production are discussed in detail.

Biolistic transformation of Carrizo citrange (Citrus sinensis Osb. × Poncirus trifoliata L. Raf.).

PubMed

Wu, Hao; Acanda, Yosvanis; Jia, Hongge; Wang, Nian; Zale, Janice

2016-09-01

The development of transgenic citrus plants by the biolistic method. A protocol for the biolistic transformation of epicotyl explants and transgenic shoot regeneration of immature citrange rootstock, cv. Carrizo (Citrus sinensis Osb. × Poncirus trifoliata L. Raf.) and plant regeneration is described. Immature epicotyl explants were bombarded with a vector containing the nptII selectable marker and the gfp reporter. The number of independent, stably transformed tissues/total number of explants, recorded by monitoring GFP fluorescence 4 weeks after bombardment was substantial at 18.4 %, and some fluorescing tissues regenerated into shoots. Fluorescing GFP, putative transgenic shoots were micro-grafted onto immature Carrizo rootstocks in vitro, confirmed by PCR amplification of nptII and gfp coding regions, followed by secondary grafting onto older rootstocks grown in soil. Southern blot analysis indicated that all the fluorescing shoots were transgenic. Multiple and single copies of nptII integrations were confirmed in five regenerated transgenic lines. There is potential to develop a higher throughput biolistics transformation system by optimizing the tissue culture medium to improve shoot regeneration and narrowing the window for plant sampling. This system will be appropriate for transformation with minimal cassettes.

The Spectrum Analysis Solution (SAS) System: Theoretical Analysis, Hardware Design and Implementation

PubMed Central

Pooler, Richard K.; Martone, Anthony F.; Gallagher, Kyle A.; Sherbondy, Kelly D.

2018-01-01

This paper describes a multichannel super-heterodyne signal analyzer, called the Spectrum Analysis Solution (SAS), which performs multi-purpose spectrum sensing to support spectrally adaptive and cognitive radar applications. The SAS operates from ultrahigh frequency (UHF) to the S-band and features a wideband channel with eight narrowband channels. The wideband channel acts as a monitoring channel that can be used to tune the instantaneous band of the narrowband channels to areas of interest in the spectrum. The data collected from the SAS has been utilized to develop spectrum sensing algorithms for the budding field of spectrum sharing (SS) radar. Bandwidth (BW), average total power, percent occupancy (PO), signal-to-interference-plus-noise ratio (SINR), and power spectral entropy (PSE) have been examined as metrics for the characterization of the spectrum. These metrics are utilized to determine a contiguous optimal sub-band (OSB) for a SS radar transmission in a given spectrum for different modalities. Three OSB algorithms are presented and evaluated: the spectrum sensing multi objective (SS-MO), the spectrum sensing with brute force PSE (SS-BFE), and the spectrum sensing multi-objective with brute force PSE (SS-MO-BFE). PMID:29470448

The categorisation of swimming start performance with reference to force generation on the main block and footrest components of the Omega OSB11 start blocks.

PubMed

Slawson, Sian E; Conway, Paul P; Cossor, Jodi; Chakravorti, Nandini; West, Andrew A

2013-01-01

Work presented in this paper provides a methodology for categorising swimming start performance based on peak force production on the main block and footrest components of the Omega OSB11 starting block. A total of 46 elite British swimmers were tested, producing over 1000 start trials. Overwater cameras were synchronised to a specifically designed start block that allowed the measurement of force production via two sets of four, tri-axis, force transducers; one set in the main block and one in the footrest. Data were then analysed, segregating trials for gender. Each start was categorised, with respect to the peak force production in horizontal and vertical components, into one of nine categories. Three performance indicators, i.e. block time, take-off velocity and distance of entry, were used to assess whether differences in performance could be correlated with these categories. Results from these data suggest that swimmers generating higher than average peak forces were more likely to produce a better overall start performance than those who produced forces lower than the average, for this population of athletes.

Pressed boride cathodes

NASA Technical Reports Server (NTRS)

Wolski, W.

1985-01-01

Results of experimental studies of emission cathodes made from lanthanum, yttrium, and gadolinium hexaborides are presented. Maximum thermal emission was obtained from lanthanum hexaboride electrodes. The hexaboride cathodes operated stably under conditions of large current density power draw, at high voltages and poor vacuum. A microtron electron gun with a lanthanum hexaboride cathode is described.

Thermophysical and Electronic Properties Information Analysis Center (TEPIAC): A Continuing Systematic Program on Tables of Thermophysical and Electronic Properties of Materials.

DTIC Science & Technology

1977-02-01

oxides and their mixtures, arsenides, borides, bromides , carbides , chlorides , fluoride s, nitride s, phosphides, silicides , sulfides , tellurides...ivity of alkali elements (lithium , sodium , potassium , rubi- dium , ces ium , and francium) and contains recomme nded reference values generated

Molecular Modeling of High-Temperature Oxidation of Refractory Borides

DTIC Science & Technology

2008-02-01

generate the classical potential, we adopt the van Beest , Kramer and van Santen (BKS) parameterization for Si-O interactions, but fit B-O and Si-B...seminar at Department of Aerospace and Mechanical Engineering, University of Notre Dame, March 20, 2007. 6 Los Alamos National Lab Physics & Theoretical

Genetic diversity and population structure in the threatened Oregon silverspot butterfly (Speyeria zerene hippolyta) in western Oregon and northwestern California— Implications for future translocations and the establishment of new populations

USGS Publications Warehouse

Miller, Mark P.; Mullins, Thomas D.; Haig, Susan M.

2016-09-20

Executive SummaryWe present results of population genetic analyses performed on Oregon silverspot butterflies (OSB; Speyeria zerene hippolyta) in western Oregon and northwestern California. We used DNA sequences from a 561-base pair region of the mitochondrial cytochrome oxidase subunit I (COI) gene for a dataset comprised of 112 S. z. hippolyta and 32 S. z. gloriosa individuals collected at 9 locations in western Oregon and northwestern California. The most pertinent findings thus far are summarized as follows:Among OSB populations, genetic diversity is lowest at Mount Hebo and highest at Rock Creek and Bray Point. Of the 32 haplotypes detected in OSB, only 2 were shared among populations (1 shared by Mount Hebo, Cascade Head, Bray Point, and Rock Creek, and 1 shared by Rock Creek and Lake Earl). The remaining 30 haplotypes were identified in individual populations, highlighting the strong differentiation among sites. It is unclear if the shared haplotypes represent widespread, naturally occurring genetic variation or if allele sharing among populations is due to translocation history.Using full siblings of individuals that were released at Rock Creek and Bray Point in 2012 as comparison standards, the analyses suggest that 54 percent of the sampled individuals from Bray Point were naturally recruited into the population and were not originating from the 2012 release of captive reared individuals. Likewise, 33 percent of the analyzed individuals from Rock Creek were naturally recruited. Both of these estimates may be underestimates if the shared alleles that we identified among populations are naturally occurring and not a product of the 2012 translocations.The results suggest that there are about 12–13 COI haplotypes in the Mount Hebo population. The U.S. Fish and Wildlife Service anticipates using Mount Hebo as the source of individuals when establishing new populations in the future. Nonlinear regression models based on a series of rarefaction analyses suggest that progeny from 12, 37, 109, and 326 female individuals would be required to respectively capture 25, 50, 75, and 90 percent of the allelic diversity from Mount Hebo.Phylogenetic analyses identified two different haplotype groups, but the two groups did not correspond to the different subspecies used in the analysis. One group included 22 S. z. hippolyta haplotypes and 7 haplotypes identified in S. z. gloriosa. The second group included eight haplotypes from S. z. hippolyta, three haplotypes from S. z. gloriosa, and one haplotype that was detected in both subspecies.

Mixed ionic-electronic conductors for electrodes of barium cerate-based SOFCS

NASA Astrophysics Data System (ADS)

Wu, Zhonglin

Gadolinium doped barium cerates (BCGs) have been identified as promising electrolyte materials for intermediate-temperature solid oxide fuel cells (SOFCs). It is crucial to develop compatible electrode materials for such electrolytes. Mixed ionic-electronic conductor (MIEC) electrode materials developed for SOFCs based on yttrium-stabilized zirconia (YSZ) may be used as electrode materials for BCG-based SOFCs; but a careful re-evaluation is required due to the intrinsic differences between BCG and YSZ. The performance of these electrode materials depends critically the transport of ionic and electronic species as well as gas. Accordingly, a profound understanding of transport in MIEC electrodes is imperative to effective design of high performance SOFCs. In this thesis, ambipolar transport in composite MIEC electrodes has been modeled using percolation theory to predict the effect of volume fractions of constituent phases and porosity on ambipolar conductivity. Transport and electrode kinetics of homogeneous MIEC electrodes have also been formulated under a steady-state condition to predict the distributions of ionic defects and current carried by each defect in such electrodes. Effects of catalytic properties, transport properties, and microstructure of porous electrodes and interfaces on the electrode performance are investigated. Under the guidelines of the theoretical modeling, several MIEC electrode materials are developed. Lasb{1-x}Srsb{x}Cosb{1-x}Fesb{y}Osb{3-delta} homogeneous materials are studied as cathode materials. However, the interfacial resistance seems too high due to the lack of catalytic activity at intermediate temperatures. Results indicate that Ag-Bisb{1.5}Ysb{0.5}Osb3 composite MIECs are good cathode materials when the volume fractions of constituent phases and porosity are carefully controlled. Such electrodes have low interfacial resistance, better binding strength, and smaller thermal mismatch with the BCG electrolyte, compared to other metal electrodes (such as Pt and Ag). Ni-BCG composite MIECs are studied as anode materials. It is found that electrodes prepared from NiO and reduced to Ni in situ is not catalytically active because of diffusion of NiO into BCG, which forms a resistive layer. Electrodes prepared from Ni metal and fired in an inert or reducing atmosphere exhibit low interfacial resistance and good compatibility with BCG electrolyte. Stability of these developed electrode materials is investigated under conditions pertinent to SOFCs.

Technology Solutions Case Study: Application of Spray Foam Insulation Under Plywood and OSB Roof Sheathing

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2013-11-01

Spray polyurethane foams (SPFs) have advantages over alternative insulation methods because they provide air sealing in complex assemblies, particularly roofs. Spray foam can provide the thermal, air, and vapor control layers in both new and retrofit construction. Unvented roof strategies with open cell and closed cell SPF insulation sprayed to the underside of roof sheathing have been used since the mid-1990s to provide durable and efficient building enclosures. However, there have been isolated incidents of failures (either sheathing rot or SPF delamination) that raise some general concerns about the hygrothermal performance and durability of these systems. The primary risks formore » roof systems are rainwater leaks, condensation from diffusion and air leakage, and built-in construction moisture. In this project, Building Science Corporation investigated rain and built-in construction moisture and vapor drives. Research involved both hygrothermal modeling of a range of rain water leakage scenarios and field evaluations of in-service residential roofs. Other variables considered were climate zone, orientation, interior relative humidity, and the vapor permeance of the coating applied to the interior face of open cell SPF.« less

AISI/DOE Technology Roadmap Program: Development of Cost-effective, Energy-efficient Steel Framing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nader R. Elhajj

2003-01-06

Steel members in wall construction form a thermal bridge that interrupts the insulation layer of a wall. This causes higher rate of heat transfer by conduction through the wall framing than through other parts of the wall. One method to reduce the thermal bridging effect is to provide a break, such as insulating sheathing. A thermally efficient slit-web and stud was developed in this program to mitigate the conductivity of steel. The thermal performance of the slit-web stud was evaluated at Oak Ridge National Laboratory using hotbox testing. The thermal test results showed that the prototype slit-web stud performed 17%more » better than the solid-web stud, using R-13 fiber glass batts with exterior OSB sheathing and interior drywall. The structural behavior of this slit-web stud was evaluated in axial, bending, shear, shearwall, and stub-column tests. Test results indicated that the slitweb stud performed similarly or better than the solid-web stud in most structural performance characteristics investigated. Thus, the prototype slit-web stud has been shown to be thermally efficient, economiexecy viable, structurally sound, easily manufactured and usable in a range of residential installations.« less

Thermodynamic analysis of chemical compatibility of several compounds with Fe-Cr-Al alloys

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1993-01-01

Chemical compatibility between Fe-19.8Cr-4.8Al (weight percent), which is the base composition for the commercial superalloy MA956, and several carbides, borides, nitrides, oxides, and silicides was analyzed from thermodynamic considerations. The effect of addition of minor alloying elements, such as Ti, Y, and Y2O3, to the Fe-Cr-Al alloy on chemical compatibility between the alloy and various compounds was also analyzed. Several chemically compatible compounds that can be potential reinforcement materials and/or interface coating materials for Fe-Cr-Al based composites were identified.

Ocean studies board has new chairman

NASA Astrophysics Data System (ADS)

Katsouros, Mary Hope

John Sclater of the University of Texas at Austin has succeeded Walter Munk as chairman of the National Research Council's Ocean Studies Board. His term runs to June 30, 1991. The 17 members of OSB represent major disciplines in oceanography. The board advises the academic community and agencies of the federal government responsible for funding basic and applied research in oceanography and for maintaining the wellbeing of the oceans.

Oriented-strand-board- the wave of the future- for the building trade

Treesearch

Linda Ashton

1984-01-01

Move over, plywood. Oriented-strand board is here. It's less expensive. It's as durable. It has as many uses. And it is the wave of the future. "Oriented-strand board is a direct substitute for plywood" said Jerry Buckner, plant manager for the Martco oriented-strand board plant in Lemoyen. OSB, as it is commonly called, is a structural panel made...

Tensile and thickness swelling properties of strands from Southern hardwoods and Southern pine : effect of hot-pressing and resin application

Treesearch

Zhiyong Cai; Qinglin Wu; Guangping Han; Jong N. Lee

2007-01-01

Tensile and the moisture-induced thickness swelling properties of wood strands are among the most fundamental parameters in modeling and predicting engineering constants of strand-based composites such as oriented strandboard (OSB). The effects of hot-pressing and resin-curing on individual strand properties were investigated in this study. Strands from four Louisiana-...

Full-Scale Experimental Investigation to Quantify Building Component Ignition Vulnerability from Mulch Beds Attacked by Firebrand Showers

PubMed Central

Manzello, Samuel L.; Suzuki, Sayaka; Nii, Daisaku

2015-01-01

Structure ignition by wind-driven firebrand showers is an important fire spread mechanism in large outdoor fires. Experiments were conducted with three common mulch types (shredded hardwood mulch, Japanese Cypress wood chips, and pine bark nuggets) placed adjacent to realistic-scale reentrant corners. In the first series of experiments, mulch beds were placed adjacent to a re-entrant corner constructed with wood studs and lined with oriented strand board (OSB) as the sheathing. The premise behind conducting experiments with no siding treatments applied was predicated on the notion that bare OSB mulch contact would be a worst-case scenario, and therefore, a wall assembly in the most vulnerable state to mulch ignition. In the second series of experiments, vinyl siding was applied to the re-entrant corner assemblies (wood studs/OSB/moisture barrier/vinyl siding), and the influence of vertical separation distance (102 mm or 203 mm) on wall ignition from adjacent mulch beds was determined. The vertical separation distance was maintained by applying gypsum board to the base of the re-entrant corner. The siding itself did not influence the ignition process for the mulch beds, as the mulch beds were the first to ignite from the firebrand showers. In all experiments, it was observed that firebrands produced smoldering ignition in the mulch beds, this transitioned to flaming ignition, and the re-entrant corner assembly was exposed to the flaming mulch beds. With no siding treatments applied, the flaming mulch beds ignited the re-entrant corner, and ignition was observed to propagate to the back side of re-entrant corner assembly under all wind speeds (6 m/s to 8 m/s). With respect to the re-entrant corners fitted with vinyl siding, the mulch type, vertical separation distance, and wind speed were important parameters as to whether flaming ignition was observed to propagate to the back-side of a reentrant corner assembly. Mulches clearly pose an ignition hazard to structures in large outdoor fires. PMID:28184098

Lithium Borides - High Energy Materials

DTIC Science & Technology

2000-02-28

1993. 99, 7983. (32) Pulay P.; Hamilton. T. P. J. Chem. Phys. 1988, 88. 4926 . (33) Frisch. M. J.: Trucks. G. W.; Schlegel. H. B.: Gill, P. M. W...25] P.V. Sudhakar, K. Lammertsma, J. Chem. Phys. 99 (1993) 7929. [26] M.J. van der Woerd, K. Lammertsma, B.J. Duke, H.F. Schaefer , III, J

Two phase titanium aluminide alloy

DOEpatents

Deevi, Seetharama C.; Liu, C. T.

2001-01-01

A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

Three-dimensional nanometer scale analyses of precipitate structures and local compositions in titanium aluminide engineering alloys

NASA Astrophysics Data System (ADS)

Gerstl, Stephan S. A.

Titanium aluminide (TiAl) alloys are among the fastest developing class of materials for use in high temperature structural applications. Their low density and high strength make them excellent candidates for both engine and airframe applications. Creep properties of TiAl alloys, however, have been a limiting factor in applying the material to a larger commercial market. In this research, nanometer scale compositional and structural analyses of several TiAl alloys, ranging from model Ti-Al-C ternary alloys to putative commercial alloys with 10 components are investigated utilizing three dimensional atom probe (3DAP) and transmission electron microscopies. Nanometer sized borides, silicides, and carbide precipitates are involved in strengthening TiAl alloys, however, chemical partitioning measurements reveal oxygen concentrations up to 14 at. % within the precipitate phases, resulting in the realization of oxycarbide formation contributing to the precipitation strengthening of TiAl alloys. The local compositions of lamellar microstructures and a variety of precipitates in the TiAl system, including boride, silicide, binary carbides, and intermetallic carbides are investigated. Chemical partitioning of the microalloying elements between the alpha2/gamma lamellar phases, and the precipitate/gamma-matrix phases are determined. Both W and Hf have been shown to exhibit a near interfacial excess of 0.26 and 0.35 atoms nm-2 respectively within ca. 7 nm of lamellar interfaces in a complex TiAl alloy. In the case of needle-shaped perovskite Ti3AlC carbide precipitates, periodic domain boundaries are observed 5.3+/-0.8 nm apart along their growth axis parallel to the TiAl[001] crystallographic direction with concomitant composition variations after 24 hrs. at 800°C.

Creep behavior of sweetgum OSB: Effect of load level and relative humidity

Treesearch

J.H. Pu; R.C. Tang; Chung-Yun Hse

1994-01-01

flexural creep behavior of laboratory-fabricated sweetgum oriented strandboard (0SB), under constant (65% and 95%) and cyclic (65% ↔ 95% at a 96-hr. frequency) relative humidity (RH) conditions at 75°F(23.9°C) is presented. Two levels (4.5% and 6.5%) of resin content (RC) of phenol-formaldehyde were used in fabricating the test panels. Two load levels (20%...

Mechanical property loss and the occurrence of wood decay during experimental outdoor aging of wood based panels

Treesearch

Charles G. Carll; Alex C. Wiedenhoeft

2007-01-01

Small specimens of sheathing-grade oriented strandboard (OSB) and sheathing-grade plywood were evaluated for retention of mechanical properties in exterior exposure over a series of exposure times. In contrast to previous studies of this nature, specimens at prolonged exposure times were also evaluated (in something more than a cursory manner) for presence of decay....

[Changes in polyamine levels in Citrus sinensis Osb. cv. Valencia callus during somatic embryogenesis].

PubMed

Liu, Hua-Ying; Xiao, Lang-Tao; Lu, Xu-Dong; Hu, Jia-Jin; Wu, Shun; He, Chang-Zheng; Deng, Xiu-Xin

2005-06-01

Somatic embryogenetic capability and changes in polyamine level and their relationship were analyzed using the long-term (8 years) subcultured calli of Citrus sinensis Osb. cv. Valencia as materials. The results showed that endogenous polyamine contents in embryogenic calli were higher than those in non-embryogenic calli, and the embryogenetic capability was positively correlated to the levels of endogenous polyamines. When the calli were transferred to a differentiation medium, the putrescine content rapidly increased and reached a peak, then fell gradually. Applying exogenous putrescine raised the embryogenesis frequency and endogenous putrescine level. It indicated that increase in putrescine content at early stage of differentiation promoted embryogenesis. With the development of somatic embryo, spermidine content reached its the highest level at globular embryo stage, spermine content rose and reached a peak at a later stage of globular embryo development. Furthermore, changes of the putrescine, spermidine and spermine contents during somatic embryogenesis were similar in Valencia calli which had different ploidy levels, but their contents decreased following the increasing of ploidy level. Changes in arginine decarboxylase activity were positively correlated to the polyamine levels, which suggest that the later is a key factor in regulating the polyamine levels during somatic embryogenesis in citrus plants.

Decomposition of forest products buried in landfills.

PubMed

Wang, Xiaoming; Padgett, Jennifer M; Powell, John S; Barlaz, Morton A

2013-11-01

The objective of this study was to investigate the decomposition of selected wood and paper products in landfills. The decomposition of these products under anaerobic landfill conditions results in the generation of biogenic carbon dioxide and methane, while the un-decomposed portion represents a biogenic carbon sink. Information on the decomposition of these municipal waste components is used to estimate national methane emissions inventories, for attribution of carbon storage credits, and to assess the life-cycle greenhouse gas impacts of wood and paper products. Hardwood (HW), softwood (SW), plywood (PW), oriented strand board (OSB), particleboard (PB), medium-density fiberboard (MDF), newsprint (NP), corrugated container (CC) and copy paper (CP) were buried in landfills operated with leachate recirculation, and were excavated after approximately 1.5 and 2.5yr. Samples were analyzed for cellulose (C), hemicellulose (H), lignin (L), volatile solids (VS), and organic carbon (OC). A holocellulose decomposition index (HOD) and carbon storage factor (CSF) were calculated to evaluate the extent of solids decomposition and carbon storage. Samples of OSB made from HW exhibited cellulose plus hemicellulose (C+H) loss of up to 38%, while loss for the other wood types was 0-10% in most samples. The C+H loss was up to 81%, 95% and 96% for NP, CP and CC, respectively. The CSFs for wood and paper samples ranged from 0.34 to 0.47 and 0.02 to 0.27gOCg(-1) dry material, respectively. These results, in general, correlated well with an earlier laboratory-scale study, though NP and CC decomposition measured in this study were higher than previously reported. Copyright © 2013 Elsevier Ltd. All rights reserved.

(Pt{sub 1–x}Cu{sub x}){sub 3}Cu{sub 2}B and Pt{sub 9}Cu{sub 3}B{sub 5}, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salamakha, Leonid P.; Sologub, Oksana, E-mail: oksana.sologub@univie.ac.at; Stöger, Berthold

New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt{sub 1−x}Cu{sub x}){sub 3}Cu{sub 2}B (x=0.33) forms a B-filled β-Mn-type structure (space group P4{sub 1}32; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt{sub 9}Cu{sub 3}B{sub 5} (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt{sub 9}Zn{submore » 3}B{sub 5–δ}-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt{sub 6}] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt{sub 6}] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt{sub 6}] and [Pt{sub 6}] trigonal prisms, rotated perpendicularly to the central one. There is no B–B contact as well as Cu–B contact in the structure. The relationships of Pt{sub 9}Cu{sub 3}B{sub 5} structure with the structure of Ti{sub 1+x}Os{sub 2−x}RuB{sub 2} as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt{sub 1–x}Cu{sub x}){sub 3}Cu{sub 2}B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ{sub 0}H{sub C2}(0){sup WHH} of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt{sub 9}Cu{sub 3}B{sub 5} (Pt{sub 9}Zn{sub 3}B{sub 5–δ}-type structure) from electrical resistivity measurements. - Highlights: • First two copper platinum borides, (Pt{sub 0.67}Cu{sub 0.33}){sub 3}Cu{sub 2}B and Pt{sub 9}Cu{sub 3}B{sub 5} were obtained. • (Pt{sub 0.67}Cu{sub 0.33}){sub 3}Cu{sub 2}B forms a B-filled β-Mn-type structure. • Pt{sub 9}Cu{sub 3}B{sub 5} adopts a Pt{sub 9}Zn{sub 3}B{sub 5–δ}-type structure. • Boron atoms exhibit octahedral and trigonal prismatic coordination. • (Pt{sub 1–x}Cu{sub x})3Cu{sub 2}B (x=0.3) is a bulk superconductor with T{sub c} 2.06 K.« less

New examples of ternary rare-earth metal boride carbides containing finite boron carbon chains: The crystal and electronic structure of RE15B6C20 (RE=Pr, Nd)

NASA Astrophysics Data System (ADS)

Babizhetskyy, Volodymyr; Mattausch, Hansjürgen; Simon, Arndt; Hiebl, Kurt; Ben Yahia, Mouna; Gautier, Régis; Halet, Jean-François

2008-08-01

The ternary rare-earth metal boride carbides RE15B6C20 (RE=Pr, Nd) were synthesized by co-melting the elements. They exist above 1270 K. Their crystal structures were determined from single-crystal X-ray diffraction data. Both crystallize in the space group P1¯, Z=1, a=8.3431(8) Å, b=9.2492(9) Å, c=8.3581(8) Å, α=84.72(1)°, β=89.68(1)°, γ =84.23(1)° (R1=0.041 (wR2=0.10) for 3291 reflections with Io>2σ(Io)) for Pr15B6C20, and a=8.284(1) Å, b=9.228(1) Å, c=8.309(1) Å, α=84.74(1)°, β=89.68(1)°, γ=84.17(2)° (R1=0.033 (wR2=0.049) for 2970 reflections with Io>2σ(Io)) for Nd15B6C20. Their structure consists of a three-dimensional framework of rare-earth metal atoms resulting from the stacking of slightly corrugated and distorted square nets, leading to cavities filled with unprecedented B2C4 finite chains, disordered C3 entities and isolated carbon atoms, respectively. Structural and theoretical analyses suggest the ionic formulation (RE3+)15([B2C4]6-)3([C3]4-)2(C4-)2·11ē. Accordingly, density functional theory calculations indicate that the compounds are metallic. Both structural arguments as well as energy calculations on different boron vs. carbon distributions in the B2C4 chains support the presence of a CBCCBC unit. Pr15B6C18 exhibits antiferromagnetic order at TN=7.9 K, followed by a meta-magnetic transition above a critical external field B>0.03 T. On the other hand, Nd15B6C18 is a ferromagnet below TC≈40 K.

Silicate garnet studies at high pressures: A view into the Earth's mantle

NASA Astrophysics Data System (ADS)

Conrad, Pamela Gales

Silicate garnets are an abundant component in the Earth's upper mantle and transition zone. Therefore, an understanding of garnet behavior under the pressure and temperature conditions of the mantle is critical to the development of models for mantle mineralogy and dynamics. Work from three projects is presented in this report. Each investigation explores an aspect of silicate garnet behavior under high pressures. Moreover, each investigation was made possible by state-of-the-art methods that have previously been unavailable. Brillouin scattering was used to determine the elastic constants and aggregate elastic moduli of three end-member garnets at high pressures in a diamond anvil cell. These are the first high-pressure measurements of the elastic constants of end-member silicate garnets by direct measurement of acoustic velocities. The results indicate that the pressure dependence of silicate garnet elastic constants varies with composition. Therefore, extrapolation from measurements on mixed composition garnets is not possible. A new method of laser heating minerals in a diamond anvil cell has made possible the determination of the high-pressure and high-temperature stability of almandine garnet. This garnet does not transform to a silicate perovskite phase as does pyrope garnet, but it decomposes to its constituent oxides: FeO, Alsb2Osb3, and SiOsb2. These results disprove an earlier prediction that ferrous iron may expand the stability field of garnet to the lower mantle. The present results demonstrate that this is not the case. The third topic is a presentation of the results of a new technique for studying inclusions in mantle xenoliths with synchrotron X-ray microdiffraction. The results demonstrate the importance of obtaining structural as well as chemical information on inclusions within diamonds and other high-pressure minerals. An unusual phase with garnet composition is investigated and several other phases are identified from a suite of natural diamonds that are thought to have a lower mantle origin.

The relationship between functional sciatic nerve block duration and the rate of release of lidocaine from a controlled-release matrix.

PubMed

Gerner, Peter; Wang, Chi-Fei; Lee, Byung-Sang; Suzuki, Suzuko; Degirolami, Umberto; Gandhi, Ankur; Knaack, David; Strichartz, Gary

2010-07-01

Nerve blocks of long duration are often desirable in perioperative and postoperative situations. The relationship between the duration of such blocks and the rate at which a local anesthetic is released is important to know for developing a localized drug delivery system that will optimize block duration. Lidocaine concentration was varied in 1 series of formulations (OSB-L) containing a constant amount of release rate modifier. In another series (OST-R), the release rate modifier was varied while the lidocaine content was held constant. Release kinetics were measured in vitro and correlated to the in vivo duration of antinociceptive and motor block effects when the formulation was implanted next to the rat sciatic nerve. In parallel studies, rats receiving different formulations of slow-release lidocaine were fixed by intracardiac perfusion with 4% paraformaldehyde and nerve-muscle tissue taken for histopathological analysis. In this study, we have demonstrated that the most important variable for effecting functional nerve block, i.e., the blockade of impulses in the relevant fibers of the sciatic nerve, is the rate of lidocaine release at that time. For the OSB-L formulations (lidocaine concentrations of 1.875%, 3.75%, 7.5%, and 15% at a constant release rate modifier of 5%), the average in vitro release rates at 50% recovery of motor block and nociceptive block were 0.91 +/- 0.28 and 1.75 +/- 0.61 mg/h, respectively. For the OST-R formulations (16% lidocaine with release rate modifier concentrations of 1.875%, 3.75%, 7.5%, and 15%), the average in vitro release rates at 50% recovery of motor block and nociceptive block were 2.33 +/- 1.39 and 4.34 +/- 1.09 mg/h, respectively. The OSB-L formulations showed a dose-dependent increase in block duration proportional to an increase in initial lidocaine concentration, whereas the OST-R formulations showed a nonmonotonic relationship between release rate modifier concentration and block duration. The histopathological studies at 24 hours, 3, 5, or 7 days, and 4 weeks after the implantation revealed inflammatory reactions with degrees correlated with lidocaine content, but limited to the connective tissue and muscle immediately surrounding the implanted material. Despite these observed inflammatory reactions, nociceptive and motor block function returned to normal, preimplantation values in all animals. Increasing initial lidocaine content proportionately increased the duration of functional sciatic nerve block. However, decreasing the release rate per se does not give a proportional increase in block duration. Instead, there seems to be an optimal, intermediate release rate for achieving the maximum duration of block.

Evaluation of Extended Wall OSB Sheathing Connection under Combined Uplift and Shear Loading for 24-inch Heel Trusses

Treesearch

Vladimir Kochkin; Andrew DeRenzis; Xiping Wang

2014-01-01

This study was designed to evaluate the performance of the extended wall structural panel connection in resisting combined uplift and shear forces at the roof-to-wall interface with a focus on a truss heel height of 24 in. to address the expected increases in the depth of attic insulation used in Climate Zones 5 and higher. Five full-size roof-wall assemblies were...

Combustion synthesis of boride and other composites

DOEpatents

Halverson, Danny C.; Lum, Beverly Y.; Munir, Zuhair A.

1989-01-01

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B.sub.4 C/TiB.sub.2 composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B.sub.4 C and TiB.sub.2 reactants. For lightweight products the composition must be relatively rich in the B.sub.4 C component. B.sub.4 C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Thermal emission property of solid solution Gd{sub 1-x}Nd{sub x}B{sub 6} (x=0, 0.6, 0.8)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing Zhang, Jiu; Hong Bao, Li; Lin Zhou, Shen, E-mail: zjiuxing@bjut.edu.cn, E-mail: Baolihong_10@yahoo.com.cn, E-mail: zhoushenlin@emails.bjut.edu.cn

2011-07-01

In this paper, to further explore the excellent emission properties of rare earth boride cathode, herein we present the synthesis, characterization and properties of polycrystalline Nd{sub 1-x}Gd{sub x}B{sub 6} (x = 0, 0.6, 0.8) bulk via arc plasma and reactive SPS. (author)

Process research into metallic pipe wear of hot chamber die casting machines and methods ofincreasing wear resistance

NASA Astrophysics Data System (ADS)

Mukhametzyanova, G. F.; Kolesnikov, MS; Mukhametzyanov, I. R.; Astatshenko, V. I.

2017-09-01

The kinetics and reasons for metallic pipe wear of hot chamberzinc alloy die casting machines are established.Increasing metallic pipe wear components wear resistance is being achieved by means of die steelДИ - 22 with electroslag remelting modification and electron-beamremelting modification and after the processes of nitriding and boriding besides.

High-pressure, high-temperature synthesis of superhard boron suboxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hubert, H.; Garvie, L.A.J.; Leinenweber, K.

A multianvil device was used to investigate the formation of B{sub x}O phases produced in the 2 to 10 GPa pressure range with temperatures between 1,000 and 1,800 C. Amorphous and crystalline B and BP were oxidized using B{sub 2}O{sub 3} and CrO{sub 3}. Using powder X-ray diffraction and parallel electron energy-loss spectroscopy (PEELS), the authors were unable to detect graphitic or diamond-structured B{sub 2}O, reported in previous studies. The refractory boride B{sub 6}O, which has the {alpha}-rhombohedral boron structure, is the dominant suboxide in the P and T range of the investigation. PEELS with a transmission electron microscope wasmore » used to characterize the boron oxides.« less

Fundamental interfacial studies of advanced solid lubricants and their operating environments

NASA Astrophysics Data System (ADS)

Gilley, Kevin

Solid lubricants are a class of materials that are utilized in applications and environments where traditional lubrication schemes cannot be implemented. A variety of materials display solid lubrication, and in this study a number of solid lubricants were investigated. Firstly, electrolessly deposited nickel boride alloys were annealed at different temperatures under a flow of oxygen. The surface chemistry, friction, and wear behavior of the coating were then investigated. It was found that when annealed above 550°C the coatings had a dramatic change in surface chemistry, where the Ni 3B had formed a thick layer of B2O3 on the surface. This oxide then reacted at ambient temperatures with moist air to form the lubricious compound H3BO3. This led to a coefficient of friction below 0.1 and a slight increase of the wear rate from 10 -8 mm3/Nm to 10-7 mm3/Nm. Secondly, the surface chemistry of advanced MoS2 based coatings that had been exposed to low earth orbit was investigated. It was found that this exposure produced the complete oxidation of the coatings. Also, exposure to the unique space environments resulted in the deposition of large amounts of contaminant SiO2 on the surface. Lastly the tribological properties of single crystal cadmium sulfide were investigated. There is nearly no knowledge of the tribological activity of cadmium sulfide in the literature, so the study was performed as an initial investigation into the material. It was discovered that cadmium sulfide did not show low friction, with a coefficient of friction of approximately 0.25, but did show low wear, with a wear rate of approximately 3x10-7 mm3/Nm.

Hydrologic flow paths control dissolved organic carbon fluxes and metabolism in an Alpine stream hyporheic zone

NASA Astrophysics Data System (ADS)

Battin, Tom J.

1999-10-01

The objective of the present paper was to link reach-scale streambed reactive uptake of dissolved organic carbon (DOC) and dissolved oxygen (DO) to subsurface flow paths in an alpine stream (Oberer Seebach (OSB)). The topography adjacent to the stream channel largely determined flow paths, with shallow hillslope groundwater flowing beneath the stream and entering the alluvial groundwater at the opposite bank. As computed from hydrometric data, OSB consistently lost stream water to groundwater with fluxes out of the stream averaging 943 ± 47 and 664 ± 45 L m-2 h-1 at low (Q < 600 L s-1) and high (Q > 600 L s-1) flow, respectively. Hydrometric segregation of streambed fluxes and physicochemical mixing analysis indicated that stream water was the major input component to the streambed with average contributions of 70-80% to the hyporheic zone (i.e., the subsurface zone where shallow groundwater and stream water mix). Surface water was also the major source of DOC with 0.512 ± 0.043 mg C m-2 h-1 to the streambed. The DOC flux from shallow riparian groundwater was lower (0.309 ± 0.071 mg C m-2 h-1) and peaked in autumn with 1.011 mg C m-2 h-1. I computed the relative proportion of downstream discharge through the streambed as the ratio of the downstream length (Ssw) a stream water parcel travels before entering the streambed to the downstream length (Shyp) a streambed water parcel travels before returning to the stream water. The relative streambed DOC retention efficiency, calculated as (input-output)/input of interstitial DOC, correlated with the proportion (Ssw/Shyp) of downstream discharge (r2 = 0.76, p = 0.006). Also, did the streambed metabolism (calculated as DO uptake from mass balance) decrease with low subsurface downstream routing, whereas elevated downstream discharge through the streambed stimulated DO uptake (r2 = 0.69, p = 0.019)? Despite the very short DOC turnover times (˜0.05 days, calculated as mean standing stock/annual input) within the streambed, the latter constitutes a net sink of DOC (˜14 mg C m-2 h-1). Along with high standing stocks of sediment associated particulate organic carbon, these results suggest microbial biofilms as the major retention and storage site of DOC in an alpine stream where large hydrologic exchange controls DOC fluxes.

New high boron content polyborane precursors to advanced ceramic materials: New syntheses, new applications

NASA Astrophysics Data System (ADS)

Guron, Marta

There is a need for new synthetic routes to high boron content materials for applications as polymeric precursors to ceramics, as well as in neutron shielding and potential medical applications. To this end, new ruthenium-catalyzed olefin metathesis routes have been devised to form new complex polyboranes and polymeric species. Metathesis of di-alkenyl substituted o-carboranes allowed the synthesis of ring-closed products fused to the carborane cage, many of which are new compounds and one that offers a superior synthetic method to one previously published. Acyclic diene metathesis of di-alkenyl substituted m-carboranes resulted in the formation of new main-chain carborane-containing polymers of modest molecular weights. Due to their extremely low char yields, and in order to explore other metathesis routes, ring opening metathesis polymerization (ROMP) was used to generate the first examples of poly(norbornenyl- o-carboranes). Monomer synthesis was achieved via a two-step process, incorporating Ti-catalyzed hydroboration to make 6-(5-norbornenyl)-decaborane, followed by alkyne insertion in ionic liquid media to achieve 1,2-R2 -3-norbornenyl o-carborane species. The monomers were then polymerized using ROMP to afford several examples of poly(norbornenyl- o-carboranes) with relatively high molecular weights. One such polymer, [1-Ph, 3-(=CH2-C5H7-CH2=)-1,2-C 2B10H10]n, had a char yield very close to the theoretical char yield of 44%. Upon random copolymerization with poly(6-(5-norbornenyl) decaborane), char yields significantly increased to 80%, but this number was well above the theoretical value implicating the formation of a boron-carbide/carbon ceramic. Finally, applications of polyboranes were explored via polymer blends toward the synthesis of ceramic composites and the use of polymer precursors as reagents for potential ultra high temperature ceramic applications. Upon pyrolysis, polymer blends of poly(6-(5-norbornenyl)-decaborane) and poly(methylcarbosilane) converted into boron-carbide/silicon-carbide ceramics with high char yields. These polymer blends were also shown to be useful as reagents for synthesis of hafnium-boride/hafnium-carbide/silicon carbide and zirconium-boride/zirconium-carbide/silicon carbide composites.

The Effect of the Heat Flux on the Self-Ignition of Oriented Strand Board

NASA Astrophysics Data System (ADS)

Hirle, Siegfried; Balog, Karol

2017-06-01

This article deals with the initiation phase of flaming and smouldering burning of oriented strand board. The influence of heat flux on thermal degradation of OSB boards, time to ignition, heat release rate and mass loss rate using thermal analysis and vertical electrical radiation panel methods were studied. Significant information on the influence of the heat flux density and the thickness of the material on time to ignition was obtained.

Inorganic Halogen Oxidizer Research.

DTIC Science & Technology

1977-02-04

the Synthesis and Characterization of NF BrF6 and Some Properties of NF SbF . . .. . .. . . .. . .. . .. . . . . . . A-1 Appendix B *Synthesis and...under progress. The results will be given in next year’s report in manuscript form. Attempts to record the Raman spectrum of CsBrF40 in HF solution...novel cations can be prepared according to: OSbF; + F6 25C p MF+ SbF + 02 R-77-112 14 However, no interaction was observed in either case. MICROWAVE

Intervention for the maintenance and improvement of physical function and quality of life among elderly disaster victims of the Great East Japan Earthquake and Tsunami.

PubMed

Greiner, Chieko; Ono, Kana; Otoguro, Chizuru; Chiba, Kyoko; Ota, Noriko

2016-08-01

The purpose of this study was to examine the effectiveness of an exercise class implemented in an area affected by the Great East Japan Earthquake and Tsunami for maintaining and improving physical function and quality of life (QOL) among elderly victims. Participants were 45 elderly disaster victims. To measure the effectiveness of the exercise classes, results on the Functional Reach Test (FRT), Timed Up and Go Test (TUG), One-leg Standing Balance (OSB), and Chair Stand Test (CST) were measured at the beginning of the exercise classes, and after 3 and 6months. In order to assess health-related QOL, the 8-item Short-Form Health Survey (SF-8) was carried out at the beginning of the exercise classes, and after 1, 3, and 6months. Of the 45 people who consented to participate, 27 continued the program for 6months and were used for analysis. Analysis of the results for FRT, OSB, and CST showed significant improvements (respectively, p=.000, .007, and .000). SF-8 showed significant increases for the subscales of bodily pain (p=.004), general health perception (p=.001), and mental health (p=.035). By continuing an exercise program for 6months, improvements were seen in lower limb muscle strength and balance functions. Effectiveness for HRQOL was also observed. Copyright © 2016 Elsevier Inc. All rights reserved.

Inhibitor effects of sodium benzoate on corrosion resistance of Al6061-B4C composites in NaCl and H3BO3 solutions

NASA Astrophysics Data System (ADS)

Rafi-ud-din; Shafqat, Q. A.; Shahzad, M.; Ahmad, Ejaz; Asghar, Z.; Rafiq, Nouman; Qureshi, A. H.; Syed, Waqar adil; asim Pasha, Riffat

2016-12-01

Sodium benzoate (SB) is used for the first time to inhibit the corrosion of Al6061-B4C composites in H3BO3 and NaCl solutions. Al6061100-x -x wt% B4C (x = 0, 5, and 10) composites are manufactured by a powder metallurgy route. The corrosion inhibition efficiency of SB is investigated as a function of the volume fractions of B4C particles by using potentiodynamic polarization and electrochemical impedance techniques. Without the use of an inhibitor, an increase of the B4C particles in the composite decreases the corrosion resistance of Al6061-B4C composites. It is found that SB is an efficient corrosion inhibitor for Al6061-B4C composites in both investigated solutions. The corrosion inhibition efficiency of SB increases with an increase in B4C content. Since SB is an adsorption type inhibitor, it is envisaged that an extremely thin layer of molecules adsorbs onto the surface and suppresses the oxidation and reduction. It is found that the inhibitor effect of SB is more pronounced in a H3BO3 environment than in NaCl solution. Further, the mechanism of corrosion inhibition by SB is illustrated by using optical and scanning electron microscopy of corroded samples. It is found that the adsorption of benzoate ions on the Al surface and its bonding with Al3+ ions forms a hydrophobic layer on top of the exposed Al surface, which enhances the protection against dissolved boride ions.

Development of CVD mullite coatings for Si-based ceramics

NASA Astrophysics Data System (ADS)

Auger, Michael Lawrence

1999-09-01

To raise fuel efficiencies, the next generation of engines and fuel systems must be lighter and operate at higher temperatures. Ceramic-based materials, which are considerably lighter than metals and can withstand working temperatures of up to 1400sp°C, have been targeted to replace traditional metal-based components. The materials used in combustion environments must also be capable of withstanding erosion and corrosion caused by combustion gases, particulates, and deposit-forming corrodants. With these demanding criteria, silicon-based ceramics are the leading candidate materials for high temperature engine and heat exchanger structural components. However, these materials are limited in gaseous environments and in the presence of molten salts since they form liquid silicates on exposed surfaces at temperatures as low as 800sp°C. Protective coatings that can withstand higher operating temperatures and corrosive atmospheres must be developed for silicon-based ceramics. Mullite (3Alsb2Osb3{*}2SiOsb2) was targeted as a potential coating material due to its unique ability to resist corrosion, retain its strength, resist creep, and avoid thermal shock failure at elevated temperatures. Several attempts to deposit mullite coatings by various processing methods have met with limited success and usually resulted in coatings that have had pores, cracks, poor adherence, and required thermal post-treatments. To overcome these deficiencies, the direct formation of chemically vapor deposited (CVD) mullite coatings has been developed. CVD is a high temperature atomistic deposition technique that results in dense, adherent crystalline coatings. The object of this dissertation was to further the understanding of the CVD mullite deposition process and resultant coating. The kinetics of CVD mullite deposition were investigated as a function of the following process parameters: temperature, pressure, and the deposition reactor system. An empirical kinetic model was developed indicating that an intermediate gaseous reaction is significant to the growth rate of mullite. CVD mullite coatings were deposited on SiC and Sisb3Nsb4 substrates and subjected to both simulated coal gasification and simulated jet fuel combustion conditions. Corrosion resistance of CVD mullite coated ceramics was superior to traditional refractory materials including alumina, solid mullite, Sisb3Nsb4, and silicon carbide.

Vapor pressure and evaporation rate of certain heat-resistant compounds in a vacuum at high temperatures

NASA Technical Reports Server (NTRS)

Bolgar, A. S.; Verkhoglyadova, T. S.; Samsonov, G. V.

1985-01-01

The vapor pressure and evaporation rate of borides of titanium, zirconium, and chrome; and of strontium and carbides of titanium, zirconium, and chrome, molybdenum silicide; and nitrides of titanium, niobium, and tantalum in a vacuum were studied. It is concluded that all subject compounds evaporate by molecular structures except AlB sub 12' which dissociates, losing the aluminum.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

LINER FOR EXTRUSION BILLET CONTAINERS

DTIC Science & Technology

Shrink-fit assembly device for buildup of ceramic-coated liner and sleeve assemblies was tested and modified to develop desired temperatures and...preliminary evaluation of suitability for extrusion liner use. Procedures were developed for welding short, hollow ceramic cylinders of high-strength metal...carbides and borides to form a ceramic extrusion liner of suitable length. Disassembly tooling for rapid separation of shrink-fitted sleeves from a worn

Combustion synthesis of boride and other composites

DOEpatents

Halverson, D.C.; Lum, B.Y.; Munir, Z.A.

1988-07-28

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B/sub 4/C/TiB/sub 2/ composites is described. It is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B/sub 4/C and TiB/sub 2/ reactants. For lightweight products the composition must be relatively rich in the B/sub 4/C component. B/sub 4/C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component. 9 figs., 4 tabs.

Tissue Engineering Platforms to Replicate the Tumor Microenvironment of Multiple Myeloma.

PubMed

Zhang, Wenting; Lee, Woo Y; Zilberberg, Jenny

2017-01-01

We described here the manufacturing and implementation of two prototype perfusion culture devices designed primarily for the cultivation of difficult-to-preserve primary patient-derived multiple myeloma cells (MMC). The first device consists of an osteoblast (OSB)-derived 3D tissue scaffold constructed in a perfused microfluidic environment. The second platform is a 96-well plate-modified perfusion culture device that can be utilized to reconstruct several tissue and tumor microenvironments utilizing both primary human and murine cells. This culture device was designed and fabricated specifically to: (1) enable the preservation of primary MMC for downstream use in biological studies and chemosensitivity analyses and, (2) provide a high-throughput format that is compatible with plate readers specifically seeing that this system is built on an industry standard 96-well tissue culture plate.

A study of the microstructure of a rapidly solidified nickel-base superalloy modified with boron. M.S. Thesis. Final Contractor Report

NASA Technical Reports Server (NTRS)

Speck, J. S.

1986-01-01

The microstructures of melt-spun superalloy ribbons with variable boron levels have been studied by transmission electron microscopy. The base alloy was of approximate composition Ni-11% Cr-5%Mo-5%Al-4%Ti with boron levels of 0.06, 0.12, and 0.60 percent (all by weight). Thirty micron thick ribbons display an equiaxed chill zone near the wheel contact side which develops into primary dendrite arms in the ribbon center. Secondary dendrite arms are observed near the ribbon free surface. In the higher boron bearing alloys, boride precipitates are observed along grain boundaries. A concerted effort has been made to elucidate true grain shapes by the use of bright field/dark field microscopy. In the low boron alloy, grain shapes are often convex, and grain faces are flat. Boundary faces frequently have large curvature, and grain shapes form concave polygons in the higher boron level alloys. It is proposed that just after solidification, in all of the alloys studied, grain shapes were initially concave and boundaries were wavy. Boundary straightening is presumed to occur on cooling in the low boron alloy. Boundary migration is precluded in the higher boron alloys by fast precipitation of borides at internal interfaces.

Lithium insertion in carbonaceous materials containing silicon

NASA Astrophysics Data System (ADS)

Wilson, Alfred Macdonald

Three different series of silicon-containing carbonaceous materials were synthesized for use as anodes in lithium ion cells. Disordered (or pregraphitic) carbons containing nanodispersed silicon were prepared by the chemical vapour deposition (CVD) of various chlorosilanes (SiClsb4, (CHsb3)sb2Clsb2Si, and (CHsb3)sb3ClSi) with benzene in two different apparatuses. Silicon oxycarbide glasses were synthesized by the pyrolysis of over 50 silicon-containing polymers at various temperatures, although the principal materials in the study were prepared at 1000sp°C. Finally, materials which we believe to be similar to disordered carbons containing nanodispersed silicon were prepared by the pyrolysis of various blends of pitches with polysilanes. Powder X-ray diffraction was used to learn about the structure of all the materials made. Thermal gravimetric analysis was used to determine the silicon content in the CVD materials and, when coupled to a residual gas analyzer, to study the decomposition process of the polymers. Near edge X-ray absorption spectroscopy measurements of the silicon L- and K-edges of CVD materials and the silicon K-edges of silicon oxycarbides were used to learn about local chemical environments of the silicon atoms. Lithium metal electrochemical test cells of the silicon-containing CVD materials showed larger capacities (up to 500 mAh/g) than pure carbons prepared in the same way (˜300 mAh/g). The additional capacity was observed to be centered near 0.4 V on charge, the average voltage observed for the removal of lithium from a silicon-lithium alloy. Chemical analysis showed that the stoichiometries of materials made by polymer pyrolysis were distributed over a well-defined region in the Si-O-C Gibbs phase diagram. An interesting series of materials is found near the line in the Si-O-C Gibbs triangle connecting carbon to SiOsb{1.3}. Lithium metal electrochemical test cells made using all the silicon oxycarbides synthesized showed that a stoichiometry of about Sisb{.25}Csb{.45}Osb{.30} gave the maximum reversible capacity (about 900 mAh/g). However, materials near this stoichiometry exhibit large irreversible capacities (>350 mAh/g) and significant hysteresis (the voltage difference between charge and discharge) in the voltage profile (˜0.8 V). In an attempt to reduce the oxygen content in one of the silicon oxycarbide glasses, a sample was washed in a dilute solution of hydrofluoric acid (HF) for times ranging from 2 minutes to 24 hours. The material lost, at most, 40 percent of its initial mass, although there was only a small change in its stoichiometry. In addition to the techniques mentioned above, small angle X-ray scattering and BET surface area measurements were used to study the microscopic pore network that was created by the HF washing. Lithium metal electrochemical test cells made using the product of pyrolysing pitch-polysilane blends showed that the capacity increased with silicon content from 340 mAh/g for pure carbon to a maximum of 600 mAh/g for samples with about 15 atomic % silicon (Sisb{.14}Osb{.09}Csb{.77}). The capacity then decreased to near zero as the composition approached SiC. These materials contain oxygen which is correlated to irreversible capacity loss. (Abstract shortened by UMI.)

Somatic hybridization in Citrus: navel orange (C. sinensis Osb.) and grapefruit (C. paradisi Macf.).

PubMed

Ohgawara, T; Kobayashi, S; Ishii, S; Yoshinaga, K; Oiyama, I

1989-11-01

Protoplasts of navel orange, isolated from embryogenic nucellar cell suspension culture, were fused with protoplasts of grapefruit isolated from leaf tissue. The fusion products were cultured in the hormone-free medium containing 0.6 M sucrose. Under the culture conditions, somatic embryogenesis of navel orange protoplasts was suppressed, while cell division of grapefruit mesophyll protoplasts was not induced. Six embryoids were obtained and three lines regenerated to complete plants through embryogenesis. Two of the regenerated lines exhibited intermediate morphological characteristics of the parents in the leaf shape. Chromosome counts showed that these regenerated plants had expected 36 chromosomes (2n=2x=18 for each parent). The rDNA analysis using biotin-labeled rRNA probes confirmed the presence of genomes from both parents in these plants. This somatic hybridization system would be useful for the practical Citrus breeding.

Decomposition of forest products buried in landfills

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiaoming, E-mail: xwang25@ncsu.edu; Padgett, Jennifer M.; Powell, John S.

Highlights: • This study tracked chemical changes of wood and paper in landfills. • A decomposition index was developed to quantify carbohydrate biodegradation. • Newsprint biodegradation as measured here is greater than previous reports. • The field results correlate well with previous laboratory measurements. - Abstract: The objective of this study was to investigate the decomposition of selected wood and paper products in landfills. The decomposition of these products under anaerobic landfill conditions results in the generation of biogenic carbon dioxide and methane, while the un-decomposed portion represents a biogenic carbon sink. Information on the decomposition of these municipal wastemore » components is used to estimate national methane emissions inventories, for attribution of carbon storage credits, and to assess the life-cycle greenhouse gas impacts of wood and paper products. Hardwood (HW), softwood (SW), plywood (PW), oriented strand board (OSB), particleboard (PB), medium-density fiberboard (MDF), newsprint (NP), corrugated container (CC) and copy paper (CP) were buried in landfills operated with leachate recirculation, and were excavated after approximately 1.5 and 2.5 yr. Samples were analyzed for cellulose (C), hemicellulose (H), lignin (L), volatile solids (VS), and organic carbon (OC). A holocellulose decomposition index (HOD) and carbon storage factor (CSF) were calculated to evaluate the extent of solids decomposition and carbon storage. Samples of OSB made from HW exhibited cellulose plus hemicellulose (C + H) loss of up to 38%, while loss for the other wood types was 0–10% in most samples. The C + H loss was up to 81%, 95% and 96% for NP, CP and CC, respectively. The CSFs for wood and paper samples ranged from 0.34 to 0.47 and 0.02 to 0.27 g OC g{sup −1} dry material, respectively. These results, in general, correlated well with an earlier laboratory-scale study, though NP and CC decomposition measured in this study were higher than previously reported.« less

Surgical Management of Laterognathia in Orthofacial Surgery.

PubMed

García Y Sánchez, J M; Gómez Rodríguez, C L; Romero Flores, J

2017-09-01

Each year around the world, various surgical procedures are carried out with the goal of correcting laterognathia; both the intraoral vertical ramus osteotomy (IVRO) and bilateral sagittal split ramus osteotomy (OSB) have been the most used techniques in mandibular surgery. These techniques have advantages and disadvantages; for example the advantages of the OSB include: increased coefficient of friction between bony segments, for both the forward and the retroposition, as well as decrease in the time of intermaxillary fixation (IMF). Disadvantages include injury to the inferior alveolar nerve (IAN), hemorrhage, bad split, among others. The advantages of IVRO include decrease of possibility of injury to the IAN, ease of implementation of the technique, a lower incidence of hemorrhage and the short duration of the surgical procedure. Their disadvantages include: lower coefficient of friction between bony segments, requires a relatively long period of IMF. The combination between the techniques of mandibular osteotomy for the correction of minor 10 mm laterognathia is the ideal treatment, since it avoids potential recurrence. We describe two cases of patients with laterognathia greater than 6 mm associated with maxilla deformity, which were treated with combined osteotomies. At Maxillofacial Surgery Service, Specialty Hospital, National Medical Center XXI Century, we describe the advantages and disadvantages, pre and postoperative nosocomial, by comparing them with the reports of the literature. The combination of techniques in the correction of laterognathias greater than 4 mm (smaller than 10 mm) is the ideal treatment, eliminating problems of articular compression, recurrence and damage to the alveolar nerve.

(Pt1-xCux)3Cu2B and Pt9Cu3B5, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

NASA Astrophysics Data System (ADS)

Salamakha, Leonid P.; Sologub, Oksana; Stöger, Berthold; Michor, Herwig; Bauer, Ernst; Rogl, Peter F.

2015-09-01

New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt1-xCux)3Cu2B (x=0.33) forms a B-filled β-Mn-type structure (space group P4132; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt9Cu3B5 (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt9Zn3B5-δ-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt6] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt6] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt6] and [Pt6] trigonal prisms, rotated perpendicularly to the central one. There is no B-B contact as well as Cu-B contact in the structure. The relationships of Pt9Cu3B5 structure with the structure of Ti1+xOs2-xRuB2 as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt1-xCux)3Cu2B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ0HC2(0)WHH of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt9Cu3B5 (Pt9Zn3B5-δ-type structure) from electrical resistivity measurements.

Late Embryogenesis Abundant (LEA) Constitutes a Large and Diverse Family of Proteins Involved in Development and Abiotic Stress Responses in Sweet Orange (Citrus sinensis L. Osb.)

PubMed Central

Pedrosa, Andresa Muniz; Martins, Cristina de Paula Santos; Gonçalves, Luana Pereira; Costa, Marcio Gilberto Cardoso

2015-01-01

Late Embryogenesis Abundant (LEA) proteins are an ubiquitous group of polypeptides that were first described to accumulate during plant seed dehydration, at the later stages of embryogenesis. Since then they have also been recorded in vegetative plant tissues experiencing water limitation and in anhydrobiotic bacteria and invertebrates and, thereby, correlated with the acquisition of desiccation tolerance. This study provides the first comprehensive study about the LEA gene family in sweet orange (Citrus sinensis L. Osb.), the most important and widely grown fruit crop around the world. A surprisingly high number (72) of genes encoding C. sinensis LEAs (CsLEAs) were identified and classified into seven groups (LEA_1, LEA_2, LEA_3 and LEA_4, LEA_5, DEHYDRIN and SMP) based on their predicted amino acid sequences and also on their phylogenetic relationships with the complete set of Arabidopsis thaliana LEA proteins (AtLEAs). Approximately 60% of the CsLEAs identified in this study belongs to the unusual LEA_2 group of more hydrophobic LEA proteins, while the other LEA groups contained a relatively small number of members typically hydrophilic. A correlation between gene structure and motif composition was observed within each LEA group. Investigation of their chromosomal localizations revealed that the CsLEAs were non-randomly distributed across all nine chromosomes and that 33% of all CsLEAs are segmentally or tandemly duplicated genes. Analysis of the upstream sequences required for transcription revealed the presence of various stress-responsive cis-acting regulatory elements in the promoter regions of CsLEAs, including ABRE, DRE/CRT, MYBS and LTRE. Expression analysis using both RNA-seq data and quantitative real-time RT-PCR (qPCR) revealed that the CsLEA genes are widely expressed in various tissues, and that many genes containing the ABRE promoter sequence are induced by drought, salt and PEG. These results provide a useful reference for further exploration of the CsLEAs functions and applications on crop improvement. PMID:26700652

Late Embryogenesis Abundant (LEA) Constitutes a Large and Diverse Family of Proteins Involved in Development and Abiotic Stress Responses in Sweet Orange (Citrus sinensis L. Osb.).

PubMed

Pedrosa, Andresa Muniz; Martins, Cristina de Paula Santos; Gonçalves, Luana Pereira; Costa, Marcio Gilberto Cardoso

2015-01-01

Late Embryogenesis Abundant (LEA) proteins are an ubiquitous group of polypeptides that were first described to accumulate during plant seed dehydration, at the later stages of embryogenesis. Since then they have also been recorded in vegetative plant tissues experiencing water limitation and in anhydrobiotic bacteria and invertebrates and, thereby, correlated with the acquisition of desiccation tolerance. This study provides the first comprehensive study about the LEA gene family in sweet orange (Citrus sinensis L. Osb.), the most important and widely grown fruit crop around the world. A surprisingly high number (72) of genes encoding C. sinensis LEAs (CsLEAs) were identified and classified into seven groups (LEA_1, LEA_2, LEA_3 and LEA_4, LEA_5, DEHYDRIN and SMP) based on their predicted amino acid sequences and also on their phylogenetic relationships with the complete set of Arabidopsis thaliana LEA proteins (AtLEAs). Approximately 60% of the CsLEAs identified in this study belongs to the unusual LEA_2 group of more hydrophobic LEA proteins, while the other LEA groups contained a relatively small number of members typically hydrophilic. A correlation between gene structure and motif composition was observed within each LEA group. Investigation of their chromosomal localizations revealed that the CsLEAs were non-randomly distributed across all nine chromosomes and that 33% of all CsLEAs are segmentally or tandemly duplicated genes. Analysis of the upstream sequences required for transcription revealed the presence of various stress-responsive cis-acting regulatory elements in the promoter regions of CsLEAs, including ABRE, DRE/CRT, MYBS and LTRE. Expression analysis using both RNA-seq data and quantitative real-time RT-PCR (qPCR) revealed that the CsLEA genes are widely expressed in various tissues, and that many genes containing the ABRE promoter sequence are induced by drought, salt and PEG. These results provide a useful reference for further exploration of the CsLEAs functions and applications on crop improvement.

Method to produce catalytically active nanocomposite coatings

DOEpatents

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

2016-02-09

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

Computer Modeling of Ceramic Boride Composites

DTIC Science & Technology

2014-11-01

the reinforcer deform elastically, for the theoretical strength of the composite it can be written [46] BBBAAABBAAK EE δεδεσδσδσ +=+= (51) where...coefficients of thermal expansion. Approximately linear expansion coefficient of the composite is determined by the relation [52] EEE BBBAAAk...1 δαδαα ⋅+⋅= , (58) where AE and BE are Young moduli of components, and E – average modulus for composition BBAA EEE δδ

Ground State Structures of Boron-Rich Rhodium Boride: An Ab Initio Study

NASA Astrophysics Data System (ADS)

Chu, Bin-Hua; Zhao, Yuan; Yan, Jin-Liang; Li, Da

2018-01-01

Not Available Supported by the Natural Science Foundation of Shandong Province under Grant Nos ZR2016AP02, ZR2016FM38 and ZR2016EMP01, the Innovation Project of Ludong University under Grant No LB2016013, the Open Project of State Key Laboratory of Superhard Materials of Jilin University under Grant No 201605, and the National Natural Science Foundation of China under Grant Nos 11704170 and 61705097.