Toward emotional interactive videogames for children with autism spectrum disorder

Universal Access in the Information Society - Technology and videogames have been proven as motivating tools for working attention and complex communication skills, especially in children with...     

Magnetization and Curie Temperature of Ilmenite–Hematite Ceramics

The morphology, structure, and magnetic properties of the magnetic semiconductor ceramic Ilmenite–Hematite (IH), (1− x )FeTiO₃– x Fe₂O₃, were studied as a function of the composition x . The magnetic ordering temperatures that we observed were consistently higher than those reported previously and were, for most of the composition range, above room temperature. We rule out the formation of Fe clusters as the origin of the magnetic properties. These magnetic properties of IH ceramics, in combination with their semiconducting characteristics, render them promising for spin-electronic applications.     

A Heat-Conduction Flow Microcalorimeter for Solute Transfer Enthalpy Determinations. Design And Calibration

Abstract

The construction of a heat-conduction flow microcalorimeter of the twin type, that uses thermopiles to detect thermal changes in the reference and reaction cells, is described. For comparative purposes, gold and silver cells, with different geometric shapes, are used. The calorimetric set is immersed in a water thermostat at a temperature of 25.000 ± 0.005°C. The thermostat is placed in a room whose temperature is controlled to 25.0 ± 0.2°C by an air thermostat.

The calibration constant of the apparatus is determined for several values of electric work and power. Values of 22 WV¹ and 14 WV¹ are obtained for the gold and silver cells, respectively.

The influence of the flow rate on the potential signal is studied. Chemical calibrations are performed with HCl-NaOH, THAM-HCl (trihidroxymethylaminomethane), and urea-water systems at different flow rates. The results are in good agreement with those reported in the literature.     

Formation and Height of the Interconnected Fractures Zone after Extraction of Thick Coal Seams with Weak Overburden in Western China

Formation of a zone of interconnected fractures during coal mining is a key factor in mine flooding. Coal mines in western China are characterized by thick coal seams with mechanically weak overburden. In situ studies including drill core analysis, drilling fluid loss measurement, and borehole video monitoring were used at the working face 101 in Shaanxi Jinjitan coal mine to explore the maximum height of the interconnected fractures zone (IFZ). Also, tests on a scaled physical model and numerical simulation based on the drilling data were used to study the formation of the fractured zone. By considering data from other mines with similar mining conditions, a logarithmic relationship was found between the maximum height of the IFZ and the thickness of coal excavation. The maximum height of the IFZ was found to be 27 times the thickness of the excavated coal seam, which is far more than in coal mining areas in eastern China. Also, the IFZ in overlying strata of the study area was arch-shaped, not saddle-shaped, as had been observed in previous studies.     

Numerical Simulation of Water Flow from the Coal Seam Floor in a Deep Longwall Mine in China

The study of groundwater flow from the coal seam floor is critical to safe mining operations in China. We developed a numerical simulation model to describe flood water pathways during mining, using the field conditions present at the no. 4196 west work face in the Panxi longwall coal mine, Shandong Province, China, Groundwater flow analysis revealed unusual values for the failure depth of the coal seam floor. The high ground stress and underground pressure, excavation length, width of working face, poor mechanical properties of aquitards, and expansion of fractures by groundwater infiltration all contribute to groundwater flow into the mine. The modeling results predict the time and longwall locations associated with the maximum likelihood of flood occurrence. Such results can be used by decision makers to improve mine design and safety.     

New hydrogels based on maleilated collagen with potential applications in tissue engineering

New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of overcoming the high degradation rate displayed by collagen that is not otherwise chemically crosslinked. Semi-interpenetrated matrices were obtained by free radical polymerization of maleilated collagen (CM) and 2-hydroxyethyl methacrylate (HEMA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as initiating system. The resulting matrices (CMH) had a sharp decrease in degradation, when compared to pure collagen. FTIR and H¹ NMR spectroscopies were used to confirm the incorporation of MA on the collagen peptide chains. The final composition of CMH was found to be strongly dependent by the concentration of maleilated collagen. The morphology of the hydrogels was studied by Scanning electron microscopy (SEM) and the macro-gel structure was confirmed. Water uptake of the synthetised hydrogels is influenced by both composition and the porosity of the matrices.     

Evaluation of the controlled release ability from the poly(2-hydroxyethyl methacrylate-co-3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane) polymer network synthesized in the presence of β-cyclodextrin

The study presents the possibility to use the 2-hydroxyethyl methacrylate--HEMA copolymer with a comonomer with spiroacetal moiety, 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane)-U, as polymer network for loading the indomethacin--INN as drug model, and also, the controlled release evaluation of the prepared bioactive system. The macromolecular compounds were prepared by radical dispersion polymerization in the presence of a pair of surfactants. The use of cyclodextrin as surfactant allowed the building of the host-guest complexes by inclusion of hydrophobic molecules. Also, the cyclodextrin supplemented the hydrogen bonds and the hydrophobic interactions responsible for the stability of the achieved complexes. The copolymers composition and the INN inclusion onto the polymeric matrix were confirmed by FTIR analysis. The porous structure of the lyophilized P(HEMA-U) samples was illustrated by SEM images. The swelling studies evidenced the interdependence between P(HEMA-U) network properties and the spiroacetal moiety amount. Thus, the copolymers presented the increase of the equilibrium swelling degree with pH and temperature. Also, the polymeric matrices manifested dual sensitivity with pH and temperature. The in vitro release of the INN drug from the polymeric network as well as the in vivo experimental studies evidenced the benefit consequence of the spiroacetal compound presence. The clinical observation of the experimental groups does not show any behavioral modifications to suggest a possible toxic effect of these polymeric formulations with and without INN.     

Thermal stability of Ln2NiO4+δ (Ln: La, Pr, Nd) and their chemical compatibility with YSZ and CGO solid electrolytes

Thermal stability and chemical compatibility with electrolyte materials for Solid Oxide Fuel Cells (SOFC) have been studied on Ruddlesden-Popper nickelates Ln₂NiO_4+δ with Ln: La, Pr and Nd. Samples of each composition prepared by three different routes, were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Different microstructures were achieved by each preparation method. The thermal stability of these compounds was analyzed by annealing all the samples at 700 and 900 °C in air. Pr₂NiO_4+δ (PNO) decomposes after 24 h of annealing at 700 °C confirming its instability at these conditions. Evidences of chemical reaction between La₂NiO_4+δ (LNO) and both Ce_0.9Gd_0.1O_1.96 (CGO) and Zr_0.92Y_0.08O_1.96 (YSZ) were observed at 700 and 900 °C, respectively. No decomposition or chemical reaction with YSZ or CGO were found for Nd₂NiO_4+δ (NNO) below 900 °C. Nevertheless, reactivity with both electrolytes was found for this compound at 1000 °C. The kinetics of these reactions strongly depends on the microstructure of Ln₂NiO_4+δ.     

Impedimetric Measurements for Monitoring Avidin-Biotin Interaction on Self-Assembled Monolayer

Avidin-biotin has been controllable immobilized on the surface of gold electrodes using mercaptopropionic acid as self-assembled monolayer. Electrochemical impedance spectroscopy (EIS) was employed to investigate the changes that appear at the electrode surface in the presence of a redox mediator, K₃[Fe(CN)₆]. An electrical model more complex than that in other studies was used to interpret the EIS measurements (Randles circuit). This model is very useful because it takes into consideration both the transfer of electrons at the electrode/electrolyte interface and the diffusion of redox species through the double layer. The model allowed us to determine some important parameters like solution resistance R_sol, charge-transfer resistance R_ct, double-layer capacitance C_dl, Warburg resistance R_W, and the diffusion time constant τ. The EIS results proved that immobilization of avidin-biotin increased the charge-transfer resistance R_ct, due to the insulating character of these molecules.