Comparison of Microstructures and Mechanical Properties for Solid Cobalt-Base Alloy Components and Biomedical Implant Prototypes Fabricated by Electron Beam Melting

The microstructures and mechanical behavior of simple, as-fabricated, solid geometries (with a density of 8.4 g/cm3), as-fabricated and fabricated and annealed femoral (knee) prototypes all produced by additive manufacturing (AM) using electron beam melting (EBM) of Co-26Cr-6Mo-0.2C powder are examined and compared in this study. Microstructures and microstructural issues are examined by optical metallography, SEM, TEM, EDS, and XRD while mechanical properties included selective specimen tensile testing and Vickers microindentation (HV) and Rockwell C-scale (HRC) hardness measurements. Orthogonal (X-Y) melt scanning of the electron beam during AM produced unique, orthogonal and related Cr23C6 carbide (precipitate) cellular arrays with dimensions of ~2μm in the build plane perpendicular to the build direction, while connected carbide columns were formed in the vertical plane, parallel to the build direction.Mechanical Engineerin

Microstructure Architecture Development in Metals and Alloys By Additive Manufacturing Using Electron Beam Melting

The concept of materials with controlled microstructural architecture (MCMA) to develop and fabricate structural materials with novel and possibly superior properties and performance characteristics is a new paradigm or paradigm extension for materials science and engineering. In the conventional materials science and engineering paradigm, structure (microstructure), properties, processing, and performance features are linked in the development of desirable materials properties and performance through processing methodologies which manipulate microstructures. For many metal or alloy systems, thermomechanical treatment combining controlled amounts of plastic deformation with heat treatment or aging cycles can achieve improved mechanical properties beyond those attainable by conventional processing alone (such as rolling or forging for example) through controlled microstructure development. In this paper we illustrate a new concept involving the fabrication of microstructural architectures by the process development and selective manipulation of these microstructures ideally defining material design space. This allows for the additional or independent manipulation of material properties by additive manufacturing (AM) using electron beam melting (EBM). Specifically we demonstrate the novel development of a carbide (M23C6) architecture in the AM of a Co-base alloy and an oxide (Cu2O) precipitate-dislocation architecture in the AM of an oxygen-containing Cu. While more conventional processing can produce various precipitate microstructures in these materials, EBM produces spatial arrays of precipitate columns or columnar-like features often oriented in the build direction. These microstructural architectures are observed by optical microscopy and scanning and transmission electron microscopy. Prospects for EBM architecture development in precipitation-hardenable Al alloys is also discussed. In the EBM build process using precursor powders, the electron beam parameters (including beam focus, scan speed and sequencing) produce localized, requisite thermodynamic regimes which create or organize the precipitate-related spatial arrays. This feature demonstrates the utility of AM not only in the fabrication of complex components, but also prospects for selective property design using CAD for MCMA development: a new or extended processing-microstructure-property-performance paradigm for materials science and engineering in advanced manufacturing involving solid free-form fabrication (SFF).Mechanical Engineerin

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: A systematic analysis for the Global Burden of Disease Study 2015

Background: The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods: We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings: Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation: Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding: Bill & Melinda Gates Foundation

A Nonzero Gap Two-dimensional Carbon Allotrope From Porous Graphene

Graphene has been one of the hottest topics in materials science in the last years. Because of its special electronic properties graphene is considered one of the most promising materials for future electronics. However, in its pristine form graphene is a gapless semiconductor, which poses some limitations to its use in some transistor electronics. Many approaches have been tried to create, in a controlled way, a gap in graphene. These approaches have obtained limited successes. Recently, hydrogenated graphene-like structures, the so-called porous graphene, have been synthesized. In this work we show, based on ab initio quantum molecular dynamics calculations, that porous graphene dehydrogenation can lead to a spontaneous formation of a nonzero gap two-dimensional carbon allotrope, called biphenylene carbon (BC). Besides exhibiting an intrinsic nonzero gap value, BC also presents well delocalized frontier orbitals, suggestive of a structure with high electronic mobility. Possible synthetic routes to obtain BC from porous graphene are addressed. © 2012 Materials Research Society.14077984The Multi-Scale Technologies Institute (MuSTI),Technological University,Int. Cent. Young Sci. (ICYS) Natl. Inst. Mater. Sci.,Angstrom Engineering Inc.Peng, H., Chen, D., Huang, J., Chikkannanavar, S., Hanisch, J., Jain, M., Peterson, D., Zhu, Y., (2008) Phys. Rev. Lett., 101, p. 145501Novoselov, Geim, A., Morozov, S., Jiang, D., Zhang, Y., Dubonos, S., Grigorieva, I., Firsov, A., (2004) Science, 306, p. 666Flores, M., Autreto, P., Legoas, S., Galvao, D., (2009) Nanotechnology, 20, p. 465704Cheng, S., Zou, K., Okino, F., Gutierrez, H., Gupta, A., Shen, N., Eklund, P., Zhu, J., (2010) Phys. Rev. B, 81, p. 205435Withers, F., Dubois, M., Savchenko, A., (2010) Phys. Rev. B, 82, p. 73403Stankovich, S., Dikin, D., Piner, R., Kohlhaas, K., Kleinhammes, A., Jia, Y., Wu, Y., Ruoff, R., (2007) Carbon, 45, p. 1558Gilje, S., Han, S., Wang, M., Wang, K., Kaner, R., (2007) Nano Lett., 7, p. 3394Gomez-Navarro, C., Weitz, R., Bittner, A., Scolari, M., Mews, A., Burghard, M., Kern, K., (2007) Nano Lett., 7, p. 3499Ruoff, R., (2008) Nature Nanotechnology, 3, p. 10Wu, X., Sprinkle, M., Li, X., Ming, F., Berger, C., De Heer, W., (2008) Phys. Rev. Lett., 101, p. 26801Kaiser, A., Gómez-Navarro, C., Sundaram, R., Burghard, M., Kern, K., (2009) Nano Lett., 9, p. 1787Sofo, J., Chaudhari, A., Barber, G., (2007) Phys. Rev. B, 75, p. 153401Ryu, S., Han, M., Maultzsch, J., Heinz, T., Kim, P., Steigerwald, M., Brus, L., (2008) Nano Lett., 8, p. 4597Elias, D., Nair, R., Mohiuddin, T., Morozov, S., Blake, P., Halsall, M., Ferrari, A., Geim, A., (2009) Science, 323, p. 610Leenaerts, O., Peelaers, H., Hernandez-Nieves, A., Partoens, B., Peeters, F., (2010), Arxiv preprint arXiv: 1009.3847Blankenburg, S., Bieri, M., Fasel, R., Mullen, K., Pignedoli, C.A., Passerone, D., (2010) Small, 6, p. 2266Du, A.J., Zhu, Z.H., Smith, S.C., (2010) J. Am. Chem. Soc., 132, p. 2876Jiang, D.E., Cooper, V.R., Dai, S., (2009) Nano Lett., 9, p. 4019Li, Y.F., Zhou, Z., Shen, P.W., Chen, Z.F., (2010) Chem. Comm., 46, p. 3672Baughman, R., Eckhardt, H., Kertesz, M., (1987) J. Chem. Phys., 87, p. 6687Baughman, R.H., Galvao, D.S., Cui, C., Wang, Y., Tománek, D., (1993) Chem. Phys. Lett., 204, p. 8Enyashin, A., Ivanovskii, A., (2011) Phys. St. Solid (B), 248, p. 1879Schulman, J.M., Disch, R.L., (2007) J. Phys Chem. A, 111, p. 10010Treier, M., Pignedoli, C., Laino, T., Rieger, R., Mullen, K., Passerone, D., Fasel, R., (2010) Nature Chem., 3, p. 61Otero, G., Biddau, G., Sanchez-Sanchez, C., Caillard, R., Lopez, M.F., Rogero, C., Palomares, F.J., Martin-Gago, J.A., (2008) Nature, 454, p. 865Hatanaka, M., (2010) Chem. Phys. Lett., 488, p. 187Bieri, M., Treier, M., Cai, J., Ait Mansour, K., Ruffieux, P., Groning, O., Groning, P., Feng, X., (2009) Chem. Commun., 45, p. 6919Schrier, J., (2010) J. Phys. Chem. Lett., 1, p. 2284Delley, B., (1988) J. Chem. Phys., 88, p. 2547Delley, B., (2000) J. Chem. Phys., 113, p. 7756. , http://www.accelrys.com, DMol3 is available from Accelrys, Inc., as part of Materials Studio and the Cerius2 program suitesPorezag, D., Frauenheim, T., Ohler, T.K., Seifert, G., Kaschner, R., (1995) Phys. Rev. B, 51, p. 12947Aradi, B., Hourahine, B., Frauenheim, T., (2007) J. Phys. Chem. A, 111, p. 5678Gutzleretal, R., (2009) Chem. Commun., 445

Formulação com aminoácidos totais ou digestíveis em rações com níveis decrescentes de proteína bruta para frangos de corte de 21 a 42 dias de idade Total and digestible amino acids formulation in diets with decreasing levels of crude protein for broilers from 21 to 42 days of age

Foram realizados dois experimentos para avaliar a formulação de rações para frangos de corte com redução do nível de proteína bruta (PB) e suplementadas com aminoácidos sintéticos, formuladas com base nos aminoácidos totais - AAT (experimento 1) ou digestíveis - AAD (experimento 2). Os experimentos foram conduzidos no período de 3 a 6 semanas de idade das aves. Em ambos os experimentos, os quatros níveis de PB foram: 20,8; 19,7; 18,6 e 17,5% PB. No experimento 2, também foram testados outros dois tratamentos com rações contendo 20,8 e 17,5% de PB e alta digestibilidade (ADig), à base de milho, farelo de soja, amido de milho e proteína isolada de soja. Nos dois experimentos, o consumo de ração não foi afetado pela redução de PB. No experimento 1, o ganho de peso (GP), a conversão alimentar (CA) e os rendimentos de peito e de coxa foram afetados negativamente pela redução dos níveis de PB, enquanto, no experimento 2 estas variáveis não foram influenciadas. No entanto, em ambos os experimentos, na semana de 21 a 28 dias, o GP e a CA foram influenciados negativamente pela redução dos níveis de PB na ração. Com o decréscimo no nível de PB, a digestibilidade da matéria seca (MS) e da matéria orgânica (MO) aumentou no experimento 2, em virtude da menor inclusão de farelo de soja. Em ambos os experimentos, a retenção relativa de proteína foi superior para rações com baixos níveis de PB. No experimento 2, apesar de os níveis de PB não terem influenciado o desempenho, a ração de ADig proporcionou maior digestibilidade da MO e tendência à maior digestibilidade da MS. As rações com 17,5% PB e ADig promoveram balanço mais positivo e maior retenção relativa de proteína em comparação às de digestibilidade padrão. Considerando todos os resultados, a formulação de rações com AAD mostrou vantagens em relação aos AAT.<br>Two experiments (Exp) were carried out to evaluate diets for broilers formulated with reducing crude protein (CP) level, supplemented with synthetic amino acids, formulated based on total amino acids (TAA) (Exp 1) or digestible AA (DAA) (Exp 2). The experiments conducted in the period from 3 to 6 weeks of age of the birds. In both experiments, the four levels of CP were: 20.8, 19.7, 18.6 and 17.5% CP. In the Experiment 2, two other treatments were added: diets containing 20.8 and 17.5% CP and high digestibility (HD), based on corn, soybean meal, corn starch and soy protein isolate. In both experiments, the feed intake was not affected by CP decreasing. In Exp1, weight gain (WG), feed conversion (FC), breast and drumstick yield were negatively affected by CP reduction, meanwhile in Exp 2 those variables were not affected. However, in both experiments, in the week from 21 to 28 days of age, WG and FC were negatively influenced by CP decrease. As the CP levels decrease, the dry matter (DM) and organic matter (OM) digestibility increased in the Exp 2, due to the smaller inclusion of soybean meal. In both experiments, the relative protein retention was greater for rations with low CP levels. In Exp 2, although of the different CP levels did not affect the performance, the Hdig diets promoted higher OM digestibility and tended to have higher DM digestibility. The rations with 17.5%CP level and HDig promoted a more positive protein balance and higher relative protein retention as compared to the standard digestibility. Considering all the results, formulation with DAA showed advantages related to TAA

Bioinorganic supplementation of calcium phosphate-based bone substitutes to improve in vivo

Supplementation of CaP-based bone graft substitutes with bioinorganics such as strontium, zinc or silicon is an interesting approach to increase the biological performance in terms of bone regenerative potential of calcium phosphate (CaP)-based bone substitutes. However, thein vivoefficacy of this approach has not been systematically analyzed, yet. Consequently, we performed a systematic review using the available literature regarding the effect of bioinorganic supplementation in CaP-based biomaterials on new bone formation and material degradation in preclinical animal bone defect models and studied this effect quantitatively by performing a meta-analysis. Additional subgroup analyses were used to study the effect of different bioinorganics, animal model, or phase category of CaP-based biomaterial on bone formation or material degradation. Results show that bioinorganic supplementation increases new bone formation (standardized mean difference [SMD]: 1.43 SD, confidence interval [CI]: 1.13-1.73). Additional subgroup analysis showed that strontium, magnesium and silica significantly enhanced bone formation, while zinc did not have any effect. This effect of bioinorganic supplementation on new bone formation was stronger for DCPD or beta-TCP and biphasic CaPs than for HA or alpha-TCP (p<0.001). In general, material degradation was slightly hindered by bioinorganic supplementation (mean difference [MD]: 0.84%, CI: 0.01-1.66), with the exception of strontium that significantly enhanced degradation. Overall, bioinorganic supplementation represents an effective approach to enhance the biological performance of CaP-based bone substitutes