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Improving the mechanical properties of pure magnesium by three-roll planetary milling
Diez, M.,Kim, H.E.,Serebryany, V.,Dobatkin, S.,Estrin, Y. Elsevier Sequoia 2014 Materials science & engineering. properties, micro Vol.612 No.-
In this study three-roll planetary milling was used to trial its potential for enhancing the mechanical properties of pure magnesium. The material was subjected to several passes of planetary milling at progressively decreased temperatures, down to room temperature for the last pass. It was shown that with increased number of passes the grain size was reduced, eventually to the micron range. Concurrently, the microstructure became increasingly more uniform across the billet. After six passes pure magnesium showed an excellent combination of tensile properties at room temperature, with a yield stress of 116MPa and a strain to failure of 13%.
Design and experimental characterization of a novel passive magnetic levitating platform
E. Diez-Jimenez,R. Alcover-Sanchez,J.M. Soria,J. Pérez-Aracil,E. Pereira 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.29 No.3
This work proposes a novel contactless vibration damping and thermal isolation tripod platform based on Superconducting Magnetic Levitation (SML). This prototype is suitable for cryogenic environments, where classical passive, semi active and active vibration isolation techniques may present tribological problems due to the low temperatures and/or cannot guarantee an enough thermal isolation. The levitating platform consists of a Superconducting Magnetic Levitation (SML) with inherent passive static stabilization. In addition, the use of Operational Modal Analysis (OMA) technique is proposed to characterize the transmissibility function from the baseplate to the platform. The OMA is based on the Stochastic Subspace Identification (SSI) by using the Expectation Maximization (EM) algorithm. This paper contributes to the use of SSI-EM for SML applications by proposing a step-by-step experimental methodology to process the measured data, which are obtained with different unknown excitations: ambient excitation and impulse excitation. Thus, the performance of SSI-EM for SML applications can be improved, providing a good estimation of the natural frequency and damping ratio without any controlled excitation, which is the main obstacle to use an experimental modal analysis in cryogenic environments. The dynamic response of the 510 g levitating platform has been characterized by means of OMA in a cryogenic, 77 K, and high vacuum, 1E-5 mbar, environment. The measured vertical and radial stiffness are 9872.4 N/m and 21329 N/m, respectively, whilst the measured vertical and radial damping values are 0.5278 Nm/s and 0.8938 Nm/s. The first natural frequency in vertical direction has been identified to be 27.39 Hz, whilst a value of 40.26 Hz was identified for the radial direction. The determined damping values for both modes are 0.46% and 0.53%, respectively.
Ana Cláudia C. Nery-Diez,Iara R. Carvalho,Jaime Amaya-Farfa´,Maria Ine´s Abecia-Soria,Ce´lio K. Miyasaka,Cle´cio da S. Ferreira 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.4
Because consumption of whey protein hydrolysates is on the increase, the possibility that prolonged ingestion of whey protein hydrolysates affect the digestive system of mammals has prompted us to evaluate the enzymatic activities of pepsin, leucine-aminopeptidase, chymotrypsin, trypsin, and glutaminase in male Wistar rats fed diets containing either a commercial whey isolate or a whey protein hydrolysate with medium degree of hydrolysis and to compare the results with those produced by physical training (sedentary, sedentary-exhausted, trained, and trained-exhausted) in the treadmill for 4 weeks. The enzymatic activities were determined by classical procedures in all groups. No effect due to the form of the whey protein in the diet was seen in the activities of pepsin, trypsin, chymotrypsin, and leucine-aminopeptidase. Training tended to increase the activity of glutaminase, but exhaustion promoted a decrease in the trained animals, and consumption of the hydrolysate decreased it even further. The results are consistent with the conclusion that chronic consumption of a whey protein hydrolysate brings little or no modification of the proteolytic digestive system and that the lowering of glutaminase activity may be associated with an antistress effect, counteracting the effect induced by training in the rat.
The Evaluation of Regional Innovation and Cluster Policies : Theory and Methods
마리아안젤레스디에즈,Diez, Maria Angeles Korea Acedemic Society Industrial Complex 2007 산업클러스터 Vol.1 No.1
Regional innovation and cluster policies are the new agenda of regional policy, an agenda that began to spread over recent years throughout different countries and regions. In this context, our main question arises: how are we going to evaluate regional innovation and cluster policies? What models and methods are we going to use? Since 1990, regional and national governments have put more emphasis on evaluation as a tool directed to produce knowledge to design better policies. The objective of this article is to summarise the main challenges arising from the evaluation of regional innovation and cluster policies and make some methodological proposals that can contribute to produce better evaluations. In the first section, there is a brief presentation of regional innovation and cluster policies, followed by a more detailed analysis, in the second section, of their principal characteristics and of the main challenges posed by their evaluation. In the third section, some evaluation proposals that can help to improve current evaluation practice are presented. The paper concludes with a short number of general recommendations that we should bear in mind when designing an evaluation of regional innovation and cluster policies.
Kim, Kyoohyun,Yoon, HyeOk,Diez-Silva, Monica,Dao, Ming,Dasari, Ramachandra R,Park, YongKeun SPIE--the International Society for Optical Engine 2014 Journal of biomedical optics Vol.19 No.1
<P>We present high-resolution optical tomographic images of human red blood cells (RBC) parasitized by malaria-inducing Plasmodium falciparum (Pf)-RBCs. Three-dimensional (3-D) refractive index (RI) tomograms are reconstructed by recourse to a diffraction algorithm from multiple two-dimensional holograms with various angles of illumination. These 3-D RI tomograms of Pf-RBCs show cellular and subcellular structures of host RBCs and invaded parasites in fine detail. Full asexual intraerythrocytic stages of parasite maturation (ring to trophozoite to schizont stages) are then systematically investigated using optical diffraction tomography algorithms. These analyses provide quantitative information on the structural and chemical characteristics of individual host Pf-RBCs, parasitophorous vacuole, and cytoplasm. The in situ structural evolution and chemical characteristics of subcellular hemozoin crystals are also elucidated.</P>