Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy

[EN] beta alloys based on the Ti Nb alloy system are of growing interest to the biomaterial community. The addition of small amounts of Fe and Cr further increases beta-phase stability, improving the properties of Ti Nb alloy. However, PM materials sintered from elemental powders are inhomogeneous due to restricted solid state diffusion and mechanical alloying provides a route to enhance mixing and lemental diffusion. The microstructural characteristics and bend strength of Ti Nb (Fe Cr) alloys obtained from elemental powder mixture and mechanical alloyed powders are compared. Mechanical alloying gives more homogeneous compositions and particle morphology, characterised by rounded, significantly enlarged particles. In the sintered samples alpha and beta phase are observed. The alpha phase appears at the grain boundaries and in lamellae growing inward from the edge, and is depleted in Nb. The b phase is enriched with Nb, Fe and Cr. The addition of Fe and Cr significantly increases the mechanical properties of Ti Nb alloys, providing increased ductility.This paper is based on a presentation at Euro PM 2014, organised by EPMA in Salzburg, Austria on 21-24 September 2014. This work was funded by UPV by the Staff Training Program for Predoctoral Researchers dated 28 February 2014. The Ministry of Science and Innovation of Spain by project research MAT2011-28492-C03 and Generalitat Valenciana by ACOMP / 2014/151.Amigó Mata, A.; Zambrano, JC.; Martínez, S.; Amigó Borrás, V. (2014). Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy. Powder Metallurgy. 57(5):316-319. https://doi.org/10.1179/0032589914Z.000000000210S316319575Niinomi, M. (1998). Mechanical properties of biomedical titanium alloys. Materials Science and Engineering: A, 243(1-2), 231-236. doi:10.1016/s0921-5093(97)00806-xWen, M., Wen, C., Hodgson, P., & Li, Y. (2014). Fabrication of Ti–Nb–Ag alloy via powder metallurgy for biomedical applications. Materials & Design (1980-2015), 56, 629-634. doi:10.1016/j.matdes.2013.11.066Cremasco, A., Messias, A. D., Esposito, A. R., Duek, E. A. de R., & Caram, R. (2011). Effects of alloying elements on the cytotoxic response of titanium alloys. Materials Science and Engineering: C, 31(5), 833-839. doi:10.1016/j.msec.2010.12.013Kuroda, D., Niinomi, M., Morinaga, M., Kato, Y., & Yashiro, T. (1998). Design and mechanical properties of new β type titanium alloys for implant materials. Materials Science and Engineering: A, 243(1-2), 244-249. doi:10.1016/s0921-5093(97)00808-3Málek, J., Hnilica, F., Veselý, J., & Smola, B. (2013). Heat treatment and mechanical properties of powder metallurgy processed Ti–35.5Nb–5.7Ta beta-titanium alloy. Materials Characterization, 84, 225-231. doi:10.1016/j.matchar.2013.08.006Boyer R, Welsch G and Collings E: ‘Materials properties handbook: titanium alloys’; 1994, Materials Park, OH, ASM International.Yang, Y. L., Wang, W. Q., Li, F. L., Li, W. Q., & Zhang, Y. Q. (2009). The Effect of Aluminum Equivalent and Molybdenum Equivalent on the Mechanical Properties of High Strength and High Toughness Titanium Alloys. Materials Science Forum, 618-619, 169-172. doi:10.4028/www.scientific.net/msf.618-619.169Terayama, A., Fuyama, N., Yamashita, Y., Ishizaki, I., & Kyogoku, H. (2013). Fabrication of Ti–Nb alloys by powder metallurgy process and their shape memory characteristics. Journal of Alloys and Compounds, 577, S408-S412. doi:10.1016/j.jallcom.2011.12.166Liu, Y., Chen, L. F., Tang, H. P., Liu, C. T., Liu, B., & Huang, B. Y. (2006). Design of powder metallurgy titanium alloys and composites. Materials Science and Engineering: A, 418(1-2), 25-35. doi:10.1016/j.msea.2005.10.057Bidaux, J.-E., Closuit, C., Rodriguez-Arbaizar, M., Zufferey, D., & Carreño-Morelli, E. (2013). Metal injection moulding of low modulus Ti–Nb alloys for biomedical applications. Powder Metallurgy, 56(4), 263-266. doi:10.1179/0032589913z.000000000118Zhao, D., Chang, K., Ebel, T., Qian, M., Willumeit, R., Yan, M., & Pyczak, F. (2014). Titanium carbide precipitation in Ti–22Nb alloy fabricated by metal injection moulding. Powder Metallurgy, 57(1), 2-4. doi:10.1179/0032589914z.000000000153Zou, L. M., Yang, C., Long, Y., Xiao, Z. Y., & Li, Y. Y. (2012). Fabrication of biomedical Ti–35Nb–7Zr–5Ta alloys by mechanical alloying and spark plasma sintering. Powder Metallurgy, 55(1), 65-70. doi:10.1179/1743290111y.0000000021Suryanarayana, C. (2001). Mechanical alloying and milling. Progress in Materials Science, 46(1-2), 1-184. doi:10.1016/s0079-6425(99)00010-9EN ISO-3325·2000: ‘Sintered metal materials, excluding hardmetals. Determination of transverse rupture strength’.Afonso, C. R. M., Aleixo, G. T., Ramirez, A. J., & Caram, R. (2007). Influence of cooling rate on microstructure of Ti–Nb alloy for orthopedic implants. Materials Science and Engineering: C, 27(4), 908-913. doi:10.1016/j.msec.2006.11.001Zhao, D., Chang, K., Ebel, T., Qian, M., Willumeit, R., Yan, M., & Pyczak, F. (2013). Microstructure and mechanical behavior of metal injection molded Ti–Nb binary alloys as biomedical material. Journal of the Mechanical Behavior of Biomedical Materials, 28, 171-182. doi:10.1016/j.jmbbm.2013.08.013Angelo PC and Subramanian R: ‘Powder metallurgy: science, technology and applications’, 1–5, 105–109, 132–133; 2009, New Delhi, PHI Learning.Lee, C. M., Ju, C. P., & Chern Lin, J. H. (2002). Structure-property relationship of cast Ti-Nb alloys. Journal of Oral Rehabilitation, 29(4), 314-322. doi:10.1046/j.1365-2842.2002.00825.xLagos, M. A., & Agote, I. (2013). SPS synthesis and consolidation of TiAl alloys from elemental powders: Microstructure evolution. Intermetallics, 36, 51-56. doi:10.1016/j.intermet.2013.01.006Majumdar, P., Singh, S. B., & Chakraborty, M. (2008). Elastic modulus of biomedical titanium alloys by nano-indentation and ultrasonic techniques—A comparative study. Materials Science and Engineering: A, 489(1-2), 419-425. doi:10.1016/j.msea.2007.12.029Kim, H.-S., Kim, W.-Y., & Lim, S.-H. (2006). Microstructure and elastic modulus of Ti–Nb–Si ternary alloys for biomedical applications. Scripta Materialia, 54(5), 887-891. doi:10.1016/j.scriptamat.2005.11.001Souza, S. A., Manicardi, R. B., Ferrandini, P. L., Afonso, C. R. M., Ramirez, A. J., & Caram, R. (2010). Effect of the addition of Ta on microstructure and properties of Ti–Nb alloys. Journal of Alloys and Compounds, 504(2), 330-340. doi:10.1016/j.jallcom.2010.05.13

Cuadriceplastia de Judet : una alternativa quirúrgica para las rigideces graves en extensión de la rodilla

Introducción. La contractura en extensión de la rodilla es una complicación de las fracturas femorales con importante afectación de partes blandas. La cuadriceplastia de Judet es una alternativa quirúrgica para aumentar la movilidad. Material y métodos. Presentamos el caso de un paciente con rigidez grave de rodilla en extensión tras una fractura abierta bifocal de fémur estabilizada mediante osteosíntesis que se complicó con una infección y retardo de consolidación que requirió varias cirugías para su estabilización. Se realizó una cuadriceplastia de Judet seguida de una rehabilitación intensiva para conseguir aumentar la flexión de la rodilla. Resultados. En el postoperatorio inmediato conseguía una flexoextensión de 0-100º que se redujo a 95º a los 3 meses y se mantuvo a los 6 meses postoperatorios, con una fuerza muscular de 4 sobre 5 en cuádriceps y psoas. Conclusion. La cuadriceplastia de Judet es una técnica efectiva que permite recuperar la movilidad en caso de rigideces graves en extensión.Introduction. Extension contracture of the knee is a complication of femoral fractures with significant soft tissue injury. The Judet quadricepsplasty is a surgical alternative to increase knee range of motion. Material and methods. We report the case of a patient with severe stiffness of knee following an open bifocal femoral fracture stabilized by osteosynthesis that was complicated by an infection and delayed healing that required several surgeries for stabilization. Judet quadricepsplasty was performed followed by intensive rehabilitation for increasing knee flexion. Results. In the postoperative care flexion and extension of 0-100º was achieved, and reduced to 95º after 3 months and remained the same at 6 months postoperatively, with a muscular strength of 4 out of 5 in quadriceps and psoas. Conclusion. The Judet quadricepsplasty is an effective technique to regain mobility in case of severe extension stiffnes

Use of hyperspectral transmittance imaging to evaluate the internal quality of nectarines

[EN] The internal quality of nectarines (Prunus persica L. Batsch var. nucipersica) cv. 'Big Top' (yellow flesh) and 'Magique' (white flesh) has been inspected using hyperspectral transmittance imaging. Hyperspectral images of intact fruits were acquired in the spectral range of 630-900 nm using transmittance mode during their ripening under controlled conditions. The detection of split pit disorder and classification according to an established firmness threshold were performed using PLS-DA. The prediction of the Internal Quality Index (IQI) related to ripeness was performed using PLS-R. The most important variables were selected using interval-PLS. As a result, an accuracy of 94.7% was obtained in the detection of fruits with split pit of the 'Big Top' cultivar. Accuracies of 95.7% and 94.6% were achieved in the classification of the 'Big Top' and 'Magique' cultivars, respectively, according to the firmness threshold. The internal quality was predicted through the IQI with R-2 values of 0.88 and 0.86 for the two cultivars. The results obtained indicate the great potential of hyperspectral transmittance imaging for the assessment of the internal quality of intact nectarines.This work was partially funded by INIA and FEDER funds through project RTA2015-00078-00-00. Sandra Munera thanks INIA for the FPI-INIA grant num. 43 (CPR2014-0082), partially supported by European Union FSE funds.Munera, S.; Blasco Ivars, J.; Amigo, J.; Cubero-García, S.; Talens Oliag, P.; Aleixos Borrás, MN. (2019). Use of hyperspectral transmittance imaging to evaluate the internal quality of nectarines. Biosystems Engineering. 182:54-64. https://doi.org/10.1016/j.biosystemseng.2019.04.001S546418

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry

We present transport measurements of a tunable silicon metal-oxide-semiconductor double quantum dot device with lateral geometry. Experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. Comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.Comment: 4 pages, 3 figures, to be published in Applied Physics Letter

Magnetic exchange interaction in a pair of orbitally degenerate ions: Magnetic anisotropy of [Ti2Cl9]−3

The theory of the kinetic exchange in a pair of orbitally degenerate ions developed by the authors [J. Phys. Chem. A 102, 200 (1998)] is applied to the case of face-shared bioctahedral dimer (overall D3h-symmetry). The effective kinetic exchange Hamiltonian is found for a 2T2–2T2 system taking into account all relevant transfer pathways and charge-transfer crystal field states. The influence of different transfer integrals involved in the kinetic exchange on the energy pattern and magnetic properties of the system is examined. The role of other related interactions (trigonal crystal field, spin–orbit coupling) is also discussed in detail. Using the pseudoangular momentum representation and the technique of the irreducible tensor operators of R3-group we give a general outlook on the nontrivial symmetry properties of the effective Hamiltonian for the D3h-pair, and on the magnetic anisotropy arising from the orbital interactions specific for the case of orbital degeneracy. The magnetic properties of the binuclear unit [Ti2Cl9]−3 in Cs3Ti2Cl9 are discussed with a special emphasis on the magnetic anisotropy experimentally observed in this system. The existing exchange models for [Ti2Cl9]−3 and the concept of the effective Hamiltonian are discussed in the context of the present [email protected] ; [email protected] ; [email protected] ; [email protected]

Nitrite inhibition of microalgae induced by the competition between microalgae and nitrifying bacteria

Outdoor microalgae cultivation systems treating anaerobic membrane bioreactor (AnMBR) effluents usually present ammonium oxidising bacteria (AOB) competition with microalgae for ammonium uptake, which can cause nitrite accumulation. In literature, nitrite effects over microalgae have shown controversial results. The present study evaluates the nitrite inhibition role in a microalgae-nitrifying bacteria culture. For this purpose, pilot- and lab-scale assays were carried out. During the continuous outdoor operation of the membrane photobioreactor (MPBR) plant, biomass retention time (BRT) of 2 d favoured AOB activity, which caused nitrite accumulation. This nitrite was confirmed to inhibit microalgae performance. Specifically, continuous 5-d lab-scale assays showed a reduction in the nitrogen recovery efficiency by 32, 42 and 80% when nitrite concentration in the culture accounted for 5, 10 and 20 mg N·L−1, respectively. On the contrary, short 30-min exposure to nitrite showed no significant differences in the photosynthetic activity of microalgae under nitrite concentrations of 0, 5, 10 and 20 mg N·L−1. On the other hand, when the MPBR plant was operated at 2.5-d BRT, the nitrite concentration was reduced to negligible values due to increasing activity of microalgae and nitrite oxidising bacteria (NOB). This allowed obtaining maximum MPBR performance; i.e. nitrogen recovery rate (NRR) and biomass productivity of 19.7 ± 3.3 mg N·L−1·d−1 and 139 ± 35 mg VSS·L−1·d−1, respectively; while nitrification rate (NOxR) reached the lowest value (13.5 ± 3.4 mg N·L−1·d−1). Long BRT of 4.5 d favoured NOB growth, avoiding nitrite inhibition. However, it implied a decrease in microalgae growth and the accumulation of nitrate in the MPBR effluent. Hence, it seems that optimum BRT has to be within the range 2-4.5 d in order to favour microalgae growth with respect to AOB and NOB

Potential of VIS-NIR hyperspectral imaging and chemometric methods to identify similar cultivars of nectarine

[EN] Product inspection is essential to ensure good quality and to avoid fraud. New nectarine cultivars with similar external appearance but different physicochemical properties may be mixed in the market, causing confusion and rejection among consumers, and consequently affecting sales and prices. Hyperspectral reflectance imaging in the range of 450¿1040 nm was studied as a non-destructive method to differentiate two cultivars of nectarines with a very similar appearance but different taste. Partial least squares discriminant analysis (PLS-DA) was used to develop a prediction model to distinguish intact fruits of the cultivars using pixel-wise and mean spectrum approaches, and then the model was projected onto the complete surface of fruits allowing visual inspection. The results indicated that mean spectrum of the fruit was the most accurate method, a correct discrimination rate of 94% being achieved. Wavelength selection reduced the dimensionality of the hyperspectral images using the regression coefficients of the PLS-DA model. An accuracy of 96% was obtained by using 14 optimal wavelengths, whereas colour imaging and a trained inspection panel achieved a rate of correct classification of only 57% of the fruits.This work was partially funded by INIA and FEDER funds through project RTA2015-00078-00-00. Sandra Munera thanks INIA for the FPI-INIA grant num. 43 (CPR2014-0082), partially supported by European Union FSE funds. The authors wish to thank Fruits de Ponent (Lleida) for providing the fruit.Munera-Picazo, S.; Amigo, JM.; Aleixos Borrás, MN.; Talens Oliag, P.; Cubero-García, S.; Blasco Ivars, J. (2018). Potential of VIS-NIR hyperspectral imaging and chemometric methods to identify similar cultivars of nectarine. Food Control. 86:1-10. https://doi.org/10.1016/j.foodcont.2017.10.037S1108

High‐nuclearity mixed‐valence magnetic clusters : A general solution of the double exchange problem

We report here a general solution of the double‐exchange problem in the high‐nuclearity mixed valence systems containing arbitrary number P of the electrons delocalized over the network of N (P<N) localized spins. The developed approach is based on the successive (chainlike) spin‐coupling scheme and takes full advantage from the quantum angular momentum theory. In the framework of this approach the closed‐form analytical expressions are deduced for the matrix elements of the double exchange interaction, two‐electron transfer, and three‐center interaction that can be referred to as the potential exchange transfer. For the arbitrary nuclearity mixed‐valence systems the matrix elements of all named interactions are expressed in terms of all relevant spin quantum numbers and 6j symbols and do not contain higher order recoupling coefficients. We describe also the combined approach taking into account both angular momentum consideration and advantages of point symmetry adapted basis [email protected] , [email protected] ; [email protected] ; [email protected] ; [email protected]