Tribological behavior of bioactive multi-material structures targeting orthopedic applications

Acknowledgments This work was supported by Fundação para a Ciência e Tecnologia (FCT), Portugal through the grants SFRH/BD/140191/2018, SFRH/BD/ 128657/2017 and SFRH/BPD/112111/2015, the project PTDC/EMSTEC/ 5422/2014 and also by project NORTE 01-0145_FEDER-000018. Additionally, this work is supported by FCT with the reference project UID/EEA/04436/2019.The following study proposes a multi-material solution in which Ti6Al4V cellular structures produced by Selective Laser Melting are impregnated with bioactive materials (hydroxyapatite or β-tricalcium phosphate) using press and sintering technique. To assess the tribological response of these structures, an alumina plate was used as a counterpart in a flat-on-flat reciprocating sliding test. Ti6Al4V cellular structures impregnated with bioactive materials displayed the highest wear resistance when compared with the unreinforced structures. Among the bioactive structures, Ti6Al4V cellular structures impregnated with βTCP were the ones with higher wear resistance, having the lowest weight loss. Hence, these structures are promising multifunctional solutions for load-bearing applications by gathering suitable mechanical properties (strength and stiffness); bioactive properties and in addition an improved wear performance.info:eu-repo/semantics/publishedVersio

Estudo comparativo da fecundidade e fertilidade de Biomphalaria glabrata (Say, 1818) e Biomphalaria straminea (Dunker, 1848) em laboratório por autofecundação e fecundação cruzada

The aim of this study was to compare the fecundity and fertility of B. glabrata and B. straminea by cross- and self-fertilization. To attain this objective, laboratory-raised strains of B. glabrata and B. straminea were used. The former originated from natural breeding grounds in the municipality Paulista, state of Pernambuco, Brazil. The latter originated from irrigation ditches in the municipality of Petrolândia, in the same state. Snail populations of B. glabrata and B. straminea were maintained for 240 days in laboratory. Their fecundity was evaluated by noting the number of egg-masses, eggs and eggs per mass. Their fertility was evaluated by the number of viable eggs and the hatching rate. B. straminea was markedly more fecund than B. glabrata through cross- and self-fertilization, namely: greater egg-mass; higher egg production and more eggs per mass. Regarding fertility, there seemed to be no preferential period for occlusion to occur or a trend in the rhythm of producing viable eggs.O objetivo deste trabalho foi comparar a fecundidade e fertilidade de Biomphalaria glabrata e Biomphalaria straminea em condições de laboratório considerando a autofecundação e a fecundação cruzada. Durante oito meses, foram registrados em laboratório, o número de cápsulas ovíferas (desovas), ovos por cápsula ovífera, ovos totais, taxa de eclosão e percentual de ovos férteis dos moluscos criados individualmente e agrupados. Foram utilizados exemplares de B. glabrata de Paulista, PE e B. straminea oriunda de Petrolândia, PE. As observações foram divididas por faixa etária no periódo de 0 a 240 dias. Os resultados obtidos neste trabalho mostram que B. straminea apresenta um potencial reprodutivo maior do que B. glabrata, tanto para moluscos criados em grupo quanto para os criados individualmentes. A comparação dos valores encontrados para fecundidade dentro da mesma espécie sugere que a autofecundação como estratégia reprodutiva, é mais eficiente em B. straminea, já que as médias encontradas (número médio de capsúlas ovíferas e ovos por cápsula ovífera) são bem próximos aos valores observados nos moluscos mantidos em grupo. Com relação à fertilidade, parece não existir períodos favoráveis para a eclosão, não havendo também um ritmo e nenhuma tendência para a produção de ovos férteis

Ingestion of macroplastics by common dolphinfish (Coryphaena hippurus) in the Atlantic Ocean

dolphinfis

Suministro De La Demanda De Energía En El Procesamiento De Carne De Pollo Con Biogás

The main use of electrical energy in the chicken meat processing unit is refrigeration. About 70% of the electricity is consumed in the compressors for the refrigeration system. Through this study, the energetic viability of using biogas from poultry litter in supplying the demand for the refrigeration process was found. The meat processing unit studied has the potential to process about a hundred and sixty thousand chickens a day. The potential biogas production from poultry litter is 60,754,298.91 m3.year-1. There will be a surplus of approximately 8,103 MWh per month of electric energy generated from biogas. An economic analysis was performed considering a planning horizon of 20 years and the discount rate of 12% per year. The economic analysis was performed considering scenario 1: sale of all electricity generated by the thermoelectric facility, and scenario 2: sale of the surplus electricity generated after complying with the demands of the refrigeration process and all other electrical energy and thermal energy use. Economic indicators obtained for scenarios 1 and 2 were favorable for the project implementation. © 2016, Revista Ingenieria e Investigacion - Editorial Board. All Rights reserved.36111812

Fractional Wave-diffusion Equation With Periodic Conditions

We study a time-space fractional wave-diffusion equation with periodic conditions using Laplace transforms and Fourier series and presenting its solution in terms of three-parameter Mittag-Leffler functions. As a particular case we recover a recent result. We also present some graphics associated with particular values of the parameters. © 2012 American Institute of Physics.5312Caputo, M., Carcione, J.M., Hysteresis cycles and fatigue criteria using anelastic models based on fractional derivatives (2011) Rheol. Acta, 50 (2), pp. 107-115. , 10.1007/s00397-010-0524-zMainardi, F., Spada, G., Creep, relaxation and viscosity properties for basic fractional models in rheology (2011) Eur. Phys. J. Spec. Top., 193, pp. 133-160. , 10.1140/epjst/e2011-01387-1, e-print arXiv:cond-mat.mtrl.sci1110.3400v1Mainardi, F., Mura, A., Pagnini, G., The M-Wright function in time-fractional diffusion processes: A tutorial survey (2010) Int. J. Differ. Equations, 2010, p. 104505. , 10.1155/2010/104505, e-print arXiv:org/abs/1004.2950(2011) Fractional Dynamics, Recent Advances, , J. Klafter, S. C. Lim, R. Metzler, edited by and (World Scientific, Singapore, )Costa, F.S., Fractional thermal systems (2011) International Conference on Multimedia Technology (ICMT), , E. Capelas de Oliveira, Hangzhou, China, 26-28 JulyOliveira, E., Costa, F.S., Vaz, J., The fractional Schrödinger equation for delta potentials (2010) J. Math. Phys., 51, p. 123517. , 10.1063/1.3525976Oliveira, E., Vaz, J., Tunneling in fractional quantum mechanics (2011) J. Phys. A: Math. Theor., 44, p. 185303. , 10.1088/1751-8113/44/18/185303Machado, J.T., Kiryakova, V., Mainardi, F., Recent history of fractional calculus (2011) Nonlinear Sci. Number. Simul., 16, pp. 1140-1153. , 10.1016/j.cnsns.2010.05.027Podlubny, I., (1999) Fractional Differential Equations, , (Academic, San Diego, )Kilbas, A.A., Srivastava, H.M., Trujillo, J.J., (2006) Theory and Applications of Fractional Differential Equations, 204. , J. Van Mill, and Mathematics Studies, edited by (Elsevier, Amsterdam, )Zhang, H., Liu, F., The fundamental solutions of the space, space-time Riesz fractional partial differential equations with periodic conditions (2007) Numer. Math. J. Chin. Univ., 16, pp. 181-192Prabhakar, T.R., A singular integral equation with generalized Mittag-Leffler function in the kernel (1971) Yokohama Math. J., 19, pp. 7-25Samko, S.G., Kilbas, A.A., Marichev, O.I., (1993) Fractional Integrals and Derivatives: Theory and Applications, , (Gordon and Breach, New York, )Mainardi, F., Luchko, Y., Pagnini, G., The fundamental solution of the space-time fractional diffusion equation (2001) Fract. Calc. & Appl. Anal., 4 (2), pp. 153-192. , e-print arXiv:cond-mat.stat.mech/0702419v1Camargo, R., Charnet, R., de Oliveira, E., On the fractional Green function (2009) J. Math. Phys., 50, p. 043514. , 10.1063/1.311948

DNA vaccines against dengue virus based on the ns1 gene: The influence of different signal sequences on the protein expression and its correlation to the immune response elicited in mice

AbstractWe analyzed four DNA vaccines based on DENV-2 NS1: pcENS1, encoding the C-terminal from E protein plus the NS1 region; pcENS1ANC, similar to pcENS1 plus the N-terminal sequence from NS2a (ANC); pcTPANS1, coding the t-PA signal sequence fused to NS1; and pcTPANS1ANC, similar to pcTPANS1 plus the ANC sequence. The NS1 was detected in lysates and culture supernatants from pcTPANS1-, pcENS1- and pcENS1ANC-transfected cells and not in cells with pcTPANS1ANC. Only the pcENS1ANC leads the expression of NS1 in plasma membrane, confirming the importance of ANC sequence for targeting NS1 to cell surface. High levels of antibodies recognizing conformational epitopes of NS1 were induced in mice immunized with pcTPANS1 and pcENS1, while only few pcENS1ANC-inoculated animals presented detectable anti-NS1 IgG. Protection against DENV-2 was verified in pcTPANS1- and pcENS1-immunized mice, although the plasmid pcTPANS1 induced slight higher protective immunity. These plasmids seem to activate distinct patterns of the immune system

Multi-material Ti6Al4V & PEEK cellular structures produced by Selective Laser Melting and Hot Pressing: A tribocorrosion study targeting orthopedic applications

This work was supported by FCT through the grants SFRH/BD/128657/2017 and SFRH/BPD/112111/2015, the project PTDC/EMSTEC/5422/2014 and also by project NORTE 01–0145_FEDER-000018. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01–0145-FEDER-006941.Ti6Al4V-alloy is commonly used in dental and orthopedic applications where tribochemical reactions occur at material/bone interface. These reactions are one of the main concerns regarding Ti6Al4V implants due to the generation of wear particles, linked to the release of metallic ions in toxic concentration which occurs when TiO2 passive film is destroyed by means of wear and corrosion simultaneously. In the present study, a multi-material Ti6Al4V-PEEK cellular structure is proposed. Selective Laser Melting technique was used to produce Ti6Al4V dense and cellular structured specimens, whilst Hot-Pressing technique was employed to obtain multi-material Ti6Al4V-PEEK structures. This study investigates the tribocorrosion behavior of these materials under reciprocating sliding, comparing them with commercial forged Ti6Al4V. Open-circuit-potential was measured before, during and after sliding while dynamic coefficient of friction was assessed during sliding. The results showed an improved wear resistance and a lower tendency to corrosion for the multi-material Ti6Al4V-PEEK specimens when compared to dense and cellular structures mono-material specimens. This multi-material solution gathering Ti6Al4V and PEEK, besides being able to withstand the loads occurring after implantation on dental and orthopedic applications, is a promising alternative to fully dense metals once it enhances the tribocorrosion performance.info:eu-repo/semantics/publishedVersio

Corrosion behaviour of PEEK or β-TCP-impregnated Ti6Al4V SLM structures targeting biomedical applications

This work was supported by FCT through the grants PD/BD/140202/2018, SFRH/BD/140191/2018 and SFRH/BD/128657/2017, and the projects PTDC/EMSTEC/ 5422/2014 and NORTE-01-0145-FEDER-000018-HAMaBICo. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2019. F. TOPTAN is grateful for the financial support through the M-ERA-NET/0001/2015 project (FCT).Ti6Al4V cellular structures were produced by selective laser melting (SLM) and then filled either with beta-tricalcium phosphate (β-TCP) or PEEK (poly-ether-ether-ketone) through powder metallurgy techniques, to improve osteoconductivity and wear resistance. The corrosion behavior of these structures was explored considering its importance for the long-term performance of implants. Results revealed that the incorporation of open cellular pores induced higher electrochemical kinetics when being compared with dense structures. The impregnation of β-TCP and PEEK led to the creation of voids or gaps between the metallic matrix and the impregnated material which also influenced the corrosion behavior of the cellular structures.info:eu-repo/semantics/publishedVersio

Ti6Al4V-PEEK multi-material structures – design, fabrication and tribological characterization focused on orthopedic implants

Acknowledgements: This work was supported by FCT through the grants SFRH/BD/128657/2017 and SFRH/BPD/112111/2015, the project PTDC/EMSTEC/5422/2014 and also by project NORTE 01-0145_FEDER-000018. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.A multi-material concept that gathers Ti6Al4V and PEEK properties in a cellular structured component was designed, fabricated and investigated targeting hip implants. SLM and pressure assisted injection techniques were used to obtain Ti6Al4V-PEEK multi-material structures. Aiming to reproduce to some extension the tribological phenomena occurring during and after hip implant insertion, five tribological tests were outlined and performed. The obtained results showed that the presence of PEEK on the Ti6Al4V-PEEK cellular structures led to a substantial improvement on the wear resistance (62% reduction in the mass loss) when compared to the material currently available on market for hip implants. The multi-material solution here investigated shows a good compromise between the primary stability after implant insertion and the wear performance.info:eu-repo/semantics/publishedVersio

The Fractional Schrödinger Equation For Delta Potentials

The fractional Schrödinger equation is solved for the delta potential and the double delta potential for all energies. The solutions are given in terms of Fox's H-function. © 2010 American Institute of Physics.5112Rangarajan, G., Ding, M., (2000) Phys. Lett. A, 273, p. 322. , 10.1016/S0375-9601(00)00518-1Mainardi, F., (1996) Appl. Math. Lett., 9, p. 23. , 10.1016/0893-9659(96)00089-4Duan, J.S., (2005) J. Math. Phys., 46, p. 013504. , 10.1063/1.1819524Figueiredo Camargo, R., Capelas de Oliveira, E., Vaz, J., (2009) J. Math. Phys., 50, p. 123518. , 10.1063/1.3269587Laskin, N., (2000) Phys. Lett. A, 268, p. 298. , 10.1016/S0375-9601(00)00201-2Laskin, N., (2000) Phys. Rev. E, 62, p. 3135. , 10.1103/PhysRevE.62.3135(1995) Lévy Flights and Related Topics in Physics, 450. , M.F.Shlesinger, G.M.Zaslavsky, U.Frisch, edited by and, Lecture Notes in Physics, (Springer, New York)Guo, X., Xu, M., (2006) J. Math. Phys., 47, p. 082104. , 10.1063/1.2235026Laskin, N., (2000) Chaos, 10, p. 780. , 10.1063/1.1050284Naber, M., (2004) J. Math. Phys., 45, p. 3339. , 10.1063/1.1769611Jeng, M., Xu, S.-L.-Y., Hawkins, E., Schwarz, J.M., (2010) J. Math. Phys., 51, p. 062102. , 10.1063/1.3430552Dong, J., Xu, M., (2007) J. Math. Phys., 48, p. 072105. , 10.1063/1.2749172Butzer, P.L., Westphal, U., (2000) Applications of Fractional Calculus in Physics, pp. 1-85. , R.Hilfer, and, "An introduction to fractional calculus," in, edited by (World Scientific, Singapore)Riesz, M., (1948) Acta Math., 81, p. 1. , 10.1007/BF02395016Gradshteyn, I.S., Ryzhik, I.M., (2007) Table of Integrals, Series, and Products, , 7th ed. (Academic Press, NY)Gasiorowicz, S., (2003) Quantum Physics, , 3rd ed. (Wiley, NY)Scott, T.C., Babb, J.F., Dalmano, A., Morgan, J.D., (1993) J. Chem. Phys., 99, p. 2841. , 10.1063/1.465193Mathai, A.M., Saxena, R.K., Haubold, H.J., (2009) The H-Function, , (Springer, NY)Braaksma, B.L.J., (1962) Compos. Math., 15, p. 239. , 2013, 1964Kilbas, A.A., Srivastava, H.M., Trujillo, J.J., (2006) Theory and Applications of Fractional Differential Equations, , (Elsevier, Amsterdam)Oberhettinger, F., (1974) Tables of Mellin Transforms, , (Springer-Verlag, Berlin)Churchill, R.V., (1960) Complex Variables and Applications, , (McGraw-Hill, NY)Podlubny, I., (1998) Fractional Differential Equations, , (Academic Press, San Diego