Control on the Manifolds of Mappings with a View to the Deep Learning

Journal of Dynamical and Control Systems - Deep learning of the artificial neural networks (ANN) can be treated as a particular class of interpolation problems. The goal is to find a neural network...     

Ceramics based on calcium phosphates substituted with magnesium ions for bone regeneration

In this study, chemical precipitation methods were used to obtain ceramic materials doped with magnesium ions in order to improve the regeneration properties of materials used for tissue engineering. Two different ratios of magnesium oxide were used to dope the ceramic powder, more precisely 5% and 10%. The synthesized materials were characterized to determine the calcination temperature of the precursor powder by means of thermal analysis; to determine the mineralogical composition, X-ray diffraction was employed and the scanning electron microscopy was used to determine the microstructure. To make use of these ceramics as biomaterials, viability and proliferation cell tests have been performed. Since synthetic materials have several limitations with regard to medical applications, the materials based on HAp substituted with Mg ions are a promising solution for the regeneration of bone defects because they have a similar bone structure. The presence of Mg in the material proves to be beneficial because this element plays an important role in bone cell regeneration, and more specifically, in stimulating osteoblast proliferation. The materials synthesized in this work present a suitable morphology for uses in bone regeneration because they offer to cells a friendly environment for growth and anchoring.     

Design of ruthenium-zeolite nanocomposites for enhanced hydrocarbon synthesis from syngas

The purpose of this work is the design of metal-zeolite nanocomposite catalysts for Fischer–Tropsch synthesis, containing ruthenium nanoparticles, uniformly distributed in the hierarchical BEA zeolites. The use of ruthenium avoids the formation of inert hardly reducible inert metal silicates and metal aluminates. Carbon nanotubes with supported metal oxide nanoparticles play the role of sacrificial template, which allows creating mesoporosity and bringing metallic functionality inside the zeolite matrix. Both mesoporosity and larger micropores of the BEA zeolite facilitate the localization of metal nanoparticles within the zeolite structure and diffusion of the reacting molecules. Compared to the conventional zeolite supported metal catalysts, the synthesized hierarchical ruthenium-zeolites exhibited much higher activity and lower methane selectivity in Fischer–Tropsch synthesis.

     

Synthesis of Invar 36 type alloys from elemental and prealloyed powders by mechanical alloying

Invar 36 (Fe₆₄Ni₃₆) nanocrystalline powders were successfully obtained by the mechanical alloying process. The mechanically alloyed Invar 36 powders were obtained from both, Fe–Ni elemental and Fe–Ni₃Fe prealloyed powders. XRD, DSC and magnetic measurements were used to characterise the Invar 36 powders. The lattice parameter evolution versus temperature of Invar 36 powders was investigated by in-situ high-temperature X-ray diffraction (HT-XRD). For both, Invar 36 (Fe, Ni) and Invar 36 (Fe, Ni₃Fe) powders, the lattice parameter values are constant up to about 350°C. The magnetic measurement also indicated that the Invar 36-type alloys are formed after 16?h of milling.     

Fiber Bridging during Melt Electrowriting of Poly(ε-Caprolactone) and the Influence of Fiber Diameter and Wall Height

Melt electrowriting (MEW) is a direct-writing technology for small diameter fibers; however, due to electrostatic attraction, the technique is restricted in how close these microfibers can be positioned on the collector. Here, the minimum interfiber distance between parallel poly(ε-caprolactone) MEW microfibers is determined for different fiber diameters and number of layers on noncoated and star-shaped poly(ethylene oxide-stat-propylene oxide) (sP(EO-stat-PO))-coated glass coverslips. The effect of the fiber diameter, the number of fiber layers, and shape of turning loops affect precision and the minimum interfiber distance. Single fibers with diameter of 5, 10, and 15 µm have a minimum interfiber distance without fiber bridging of 33 ± 2.7, 54 ± 2.2, and 62 ± 2.7 µm, respectively. Increasing the number of layers to ten increases this minimum interfiber distance approximately twofold to 60 ± 3.5, 97 ± 4.5, and 102 ± 2.7 µm for the increasing fiber diameters. The sP(EO-stat-PO) slightly increases the minimum interfiber distance for the 15 µm diameter group only, with spacing for the 5 and 10 µm fibers unaffected by the coating. Identifying and determining the fabrication limits for MEW is highly instructional for users working and designing scaffolds with this technology.     

Molecularly imprinted poly(acrylonitrile‐co‐acrylic acid) matrix with sclareol

There are presented results regarding a new set of molecularly imprinted polymers (MIPs) based on acrylonitrile:acrylic acid (AN:AA) copolymer matrix. As template, it was used sclareol, an important anticancer bioactive compound, never used before for molecular imprinting. An emerging and insufficient studied MIP preparation method, namely the phase inversion, was used to prepare 0.8 mm spherical sclareol MIPs (S‐MIPs). Three AN:AA copolymers, having the initial monomer ratios 90:10, 80:20, and 70:30, were synthesized by radical copolymerization in emulsion, without emulsifier. After that, each copolymer was dissolved in the presence of the template (sclareol) in dimethylformamide. The imprinting and the morphology of these new materials were analyzed by rheology, elemental analysis, infrared spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, batch rebinding tests, and Scatchard analysis. The conclusion was that the AN:AA‐80:20 matrix proved to be the optimized solution between high rigidity (given by the AN segments) and high affinity for the template (given by AA segments), the average imprinting factor for this system being 2.67. POLYM. ENG. SCI., 54:1484–1494, 2014. © 2013 Society of Plastics Engineers     

Dynamische Verformungsmessungen an Eisenbahnbrücken mittels Mikrowelleninterferometrie

Dynamic measurements of railway bridge displacements through microwave interferometry – Part 1: measurement method The microwave interferometry is a rather new measuring technique, yet little‐known in civil engineering applications. It allows the non‐contact acquisition of structural displacements with accuracy in the sub‐millimetre range at a sampling rate of up to 4 kHz. The high sampling frequency allows also the caption of dynamic structural responses, which can be used for a straightforward determination of the main modal parameters of the structures (natural frequencies, damping ratios). Furthermore, the synchronous acquisition of the overall motion of the targeted object is possible due to a high range resolution, which facilitates a direct identification of modal shapes. This paper gives a short introduction of the measurement method and outlines its boundary conditions and limitations with respect to applications in railway bridge dynamics. The knowledge has been gained on the basis of comprehensive systematic experimental investigations performed within the frame of a cooperation project with the German Railways (Deutsche Bahn AG). As a result an evaluation matrix was created, which clearly illustrates the applicability of the microwave interferometry for different railway‐specific tasks. The second part will present selected results of microwave interferometry measurements of railway bridges in comparison to parallel conventional measurements and the corresponding numerical investigations, which were used for the validation of the measurement technique.     

Effects of equal‐channel,multiple‐angular extrusion on the physical and mechanical properties of glassy polymers

Through the examples of polycarbonate and poly(methyl acrylate), the evolution of the structure and properties of glassy polymers processed by equal‐channel multiple‐angular extrusion (ECMAE) were studied. It was demonstrated that ECMAE allowed the substantial improvement of the set of strain–strength characteristics of these materials, regardless of the direction of loading applied. With the use of the data from scanning electron microscopy, differential scanning calorimetry, and dilatometry, we found that the simultaneous growth in the strength, plasticity, and impact resistance was related to the formation of a net of biaxially oriented polymeric chains, the decrease in the free volume, and the reinforcement of intermolecular interaction. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42180.     

Phytochemical Characterization of Veronica officinalis L., V. teucrium L. and V. orchidea Crantz from Romania and Their Antioxidant and Antimicrobial Properties

Aerial parts of Veronica species are used in Romanian traditional medicine for the treatment of various conditions like kidney diseases, cough, and catarrh, and are known for their wound-healing properties. In the present study, the phenolic and sterolic content and the antioxidant and antimicrobial activities of three Veronica species (Plantaginaceae), V. officinalis L., V. teucrium L. and V. orchidea Crantz, were studied. The identification and quantification of several phenolic compounds and phytosterols were performed using LC/MS techniques and the main components were p-coumaric acid, ferulic acid, luteoline, hispidulin and β-sitosterol. More than that, hispidulin, eupatorin and eupatilin were detected for the first time in the Veronica genus. Nevertheless, representatives of the Veronica genus were never investigated in terms of their phytosterol content. The antioxidant potential investigated by Trolox equivelents antioxidant capacity (TEAC) and EPR spectroscopy revealed that V. officinalis and V. orchidea extracts presented similar antioxidant capacities, whilst the values registered for V. teucrium extract are lower. Regarding the antimicrobial activity of the investigated species, Staphylococcus aureus, Listeria monocytogenes and Listeria ivanovii were the most sensitive strains with MIC values between 3.9 and 15.62 mg/mL. The results obtained by this study may serve to promote better use of representatives from the genus Veronica as antioxidant and antimicrobial agents.