Mineralization behaviour of some new phema-based copolymers with potential uses in tissue engineering

This paper reports the mineralization ability of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloylamido glutamic acid (MAGA) based copolymers incubated in synthetic fluids. MAGA monomer was obtained by organic synthesis and next p(HEMA-co-MAGA) copolymers with different compositions were prepared by bulk radical polymerization using benzoyle peroxide as initiator and ethyleneglycol dimethacrylate as cross-linking agent. The monomer and polymers were further characterized by FTIR-ATR spectroscopy to confirm their structure. Finally, polymers ability to initiate the formation and growth of HA crystals onto their surface in synthetic fluids was proven. SEM analysis showed the formation of apatite-like crystals (calcospherites), fact confirmed also by EDX analysis

Field Line Resonances in Quiet and Disturbed Time Three-Dimensional Magnetospheres

Numerical solutions for field line resonances (FLR) in the magnetosphere are presented for three-dimensional equilibrium magnetic fields represented by two Euler potentials as B = -j Y -a, where j is the poloidal flux and a is a toroidal angle-like variable. The linearized ideal-MHD equations for FLR harmonics of shear Alfvin waves and slow magnetosonic modes are solved for plasmas with the pressure assumed to be isotropic and constant along a field line. The coupling between the shear Alfvin waves and the slow magnetosonic waves is via the combined effects of geodesic magnetic field curvature and plasma pressure. Numerical solutions of the FLR equations are obtained for a quiet time magnetosphere as well as a disturbed time magnetosphere with a thin current sheet in the near-Earth region. The FLR frequency spectra in the equatorial plane as well as in the auroral latitude are presented. The field line length, magnetic field intensity, plasma beta, geodesic curvature and pressure gradient in the poloidal flux surface are important in determining the FLR frequencies. In general, the computed shear Alfvin FLR frequency based on the full MHD model is larger than that based on the commonly adopted cold plasma model in the beq > 1 region. For the quiet time magnetosphere, the shear Alfvin resonance frequency decreases monotonically with the equatorial field line distance, which reasonably explains the harmonically structured continuous spectrum of the azimuthal magnetic field oscillations as a function of L shell in the L is less than or equal to 9RE region. However, the FLR frequency spectrum for the disturbed time magnetosphere with a near-Earth thin current sheet is substantially different from that for the quiet time magnetosphere for R > 6RE, mainly due to shorter field line length due to magnetic field compression by solar wind, reduced magnetic field intensity in the high-beta current sheet region, azimuthal pressure gradient, and geodesic magnetic field curvature

Low Latency Geo-distributed Data Analytics

Low latency analytics on geographically distributed dat-asets (across datacenters, edge clusters) is an upcoming and increasingly important challenge. The dominant approach of aggregating all the data to a single data-center significantly inflates the timeliness of analytics. At the same time, running queries over geo-distributed inputs using the current intra-DC analytics frameworks also leads to high query response times because these frameworks cannot cope with the relatively low and variable capacity of WAN links. We present Iridium, a system for low latency geo-distri-buted analytics. Iridium achieves low query response times by optimizing placement of both data and tasks of the queries. The joint data and task placement op-timization, however, is intractable. Therefore, Iridium uses an online heuristic to redistribute datasets among the sites prior to queries ’ arrivals, and places the tasks to reduce network bottlenecks during the query’s ex-ecution. Finally, it also contains a knob to budget WAN usage. Evaluation across eight worldwide EC2 re-gions using production queries show that Iridium speeds up queries by 3 × − 19 × and lowers WAN usage by 15% − 64 % compared to existing baselines

Experimental and Finite Element Analysis of the Open-Cells Porous Materials Subjected to Compression Mechanical Loading

Progress in Additive Manufacturing (AM) technology enables the fabrication of complex structures that could not be obtained with traditional manufacturing methods. One AM research area is the development and use of lightweight products with cellular structures, containing complex lattices and pores, which give improved performance and functionality. It is well known that there is a strong link between mechanical properties and architecture of samples with cellular structures. This paper presents a comparison and validation of Finite Element Analysis (FEA) simulations of cellular structures with experimental data obtained from compression tests, and degradation behaviour under load compression. The specimens, with spherical open-cells, were produced in VeroClear RGD810 photopolymer resin. Mechanical compression tests were performed to investigate the compressive behaviour and the mechanical response was registered in the form of compressive stress-strain curves. Also, using the specimens’ CAD data and compression test parameters, a Finite Element Analysis (FEA) was performed. A macroscopic analysis of the specimens’ structure and microhardness tests before and after compression tests were also carried out