Bioactivity potential of calcium alumino-silicate glasses and glass–ceramics containing nitrogen and fluorine

Calcium alumino-silicate glasses of general composition (in eq.%) 28Ca:57Si:15Al:[100 ? (x + y)]O:xN:yF (x = 0 or 20 and y = 0, 3 or 5) and their glass–ceramic counterparts were immersed in simulated body fluid (SBF) at 37 ± 0.5 °C for 28 days to assess their potential bioactivity. The glasses showed no Ca release or surface calcium phosphate deposition due to their high network connectivities (>2.55). The glass–ceramics all showed potential bioactivity, as the SBF became enriched in Ca and calcium phosphate deposits formed on their surfaces. This was a result of Ca release from crystalline phases (predominantly wollastonite in the case of CaSiAlOF glass–ceramics and gehlenite in the case of CaSiAlONF glass–ceramics). No aluminium was leached from the glass–ceramics into the SBF, due to its pH always exceeding 7.0.     

Combined heat and mass transfer by natural convection at horizontal cylinder electrodes

Simultaneous heat and mass transfer in free convection at horizontal cylinder electrodes has been investigated experimentally using the electrochemical limiting diffusion current technique. The convective flow patterns occuring have been observed using Schlieren photography. The results confirmed the use of a combined Grashof number (GR_m) to account for thermal and concentration buoyancy effects. Various combinations of electroactive species concentration, cylinder diameter and cylinder surface temperature have been used. Results have been successfully correlated by the equations , 7×10⁷ < GR_mSc< 4×10⁹ and , 4×10⁹ mSc<10¹¹ The experiments cover the range of mass transfer and heat transfer Grashof numbers 3.64×10⁴ m <3.02×10⁶, 5.67×10⁴ h <6.55×10⁶     

The effect of electrode infiltration on the performance of tubular solid oxide fuel cells under electrolysis and fuel cell modes

The electrochemical performance of two different anode supported tubular cells (50:50 wt% NiO:YSZ (yttria stabilized zirconia) or 34:66 vol.% Ni:YSZ) as the fuel electrode and YSZ as the electrolyte) under SOFC (solid oxide fuel cell) and SOEC (solid oxide electrolysis cell) modes were studied in this research. LSM (La_0.80Sr_0.20MnO_3−δ) was infiltrated into a thin porous YSZ layer to form the oxygen electrode of both cells and, in addition, SDC (Sm_0.2Ce_0.8O_1.9) was infiltrated into the fuel electrode of one of the cells. The microstructure of the infiltrated fuel cells showed a suitable distribution of fine LSM and SDC particles (50–100 nm) near the interface of electrodes and electrolyte and throughout the bulk of the electrodes. The results show that SDC infiltration not only enhances the electrochemical reaction in SOFC mode but improves the performance even more in SOEC mode. In addition, LSM infiltrated electrodes also boost the SOEC performance in comparison with standard LSM–YSZ composite electrodes, due to the well-dispersed LSM nanoparticles (favouring the electrochemical reactions) within the YSZ porous matrix.     

A first-principles study of the structural,elastic, electronic,vibrational, and optical properties of BaSe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Te<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>

The structural, elastic, electronic, vibrational, and optical properties of BaSe_1?xTe_x alloys are investigated by means of the full-potential linearized augmented plane wave method. The exchange–correlation effects are treated with the local density approximation, as well as the GGA-PBE, GGA-PBEsol, and GGA?+?mBJ schemes of the generalized gradient approximation. Ternary BaSe_1?xTe_x compounds have not yet been synthesized. Improved predictions of the structural parameters are obtained using the GGA-PBEsol approach. Calculations of the electronic and optical properties with the GGA?+?mBJ approach yield accurate results. Ternary BaSe_1?xTe_x alloys are wide-band-gap semiconductors with a direct gap Γ–Γ. The upper valence band is mainly due to Se p and Te p states, while the bottom of the conduction band results essentially from Ba d states. The dielectric function, refractive index, reflectivity, absorption coefficient, and energy-loss function are calculated in the range 0–35 eV. The increase in x gives rise to a redshift of the optical spectra. BaSe_1?xTe_x alloys exhibit reflective properties of metals in some energy ranges. The static dielectric constant ?₁(0) and the static refractive index n₀ are calculated. The investigation of the elastic and vibrational properties shows that ternary BaSe_1?xTe_x should be mechanically and dynamically stable, elastically anisotropic, brittle, and relatively soft.     

Prediction of compressive and tensile strength of Gaziantep basalts via neural networks and gene expression programming

In this paper, two soft computing approaches, which are known as artificial neural networks and Gene Expression Programming (GEP) are used in strength prediction of basalts which are collected from Gaziantep region in Turkey. The collected basalts samples are tested in the geotechnical engineering laboratory of the University of Gaziantep. The parameters, “ultrasound pulse velocity”, “water absorption”, “dry density”, “saturated density”, and “bulk density” which are experimentally determined based on the procedures given in ISRM (Rock characterisation testing and monitoring. Pergamon Press, Oxford, 1981) are used to predict “uniaxial compressive strength” and “tensile strength” of Gaziantep basalts. It is found out that neural networks are quite effective in comparison to GEP and classical regression analyses in predicting the strength of the basalts. The results obtained are also useful in characterizing the Gaziantep basalts for practical applications.     

Hydro-abrasive erosion of concrete incorporating ground blast-furnace slag and ground basaltic pumice

In this research work, an attempt has been made to find the suitability of the ground blast-furnace slag (GBS) and ground basaltic pumice (GBP) as a possible substitute for conventional crushed fine aggregate. The main purpose of this investigation is to determine the hydro-abrasive erosion (HAE) characteristics of concrete with GBS and GBP as fine aggregates.The results create perspectives of forecasting HAE of concrete structures depending on the types and amount of additives. It was found that the HAE characteristics of concrete had improved when some of the fine aggregates were replaced by GBS and GBP. As the amount of these additives increased, the mass loss of the concrete incorporating GBS + GBP decreased. This improvement can be explained partly by the decrease in the permeability and partly by the HAE resistance of the additives. In addition to these results, the HAE of concrete was strongly influenced by its compressive strength. Furthermore, the increase in the percentage of additives increased the chloride penetration depths, sharply. The results of this investigation suggest that a joint incorporation of GBS and GBP could conveniently be used to improve its HAE characteristics of concrete.     

Layout preferences concerning matching in a fully differential ΔΣ modulator design

A fully differential architecture has numerous advantages in a switched-capacitor delta-sigma modulator such as immunization to clock-induced noise, supply rejection, simple sign conversion of integrator gain and doubled output dynamic range. Efficient use of the fully differential architecture nevertheless requires a completely symmetrical layout and routing, which may contradict with the requirements of component matching. Some design choices have to be made at this point, depending on what requirements can be compromised. This paper discusses the importance of certain layout features which may serve as a guide in making these design choices. Hakan Binici was born in Istanbul, Turkey, in 1969. He received his B.Sc. and M.Sc. degrees respectively from Istanbul Technical University and the Bogazici University in Istanbul in 1989 and 1995. Since 1997 he has been working as a research scientist at the Electronics Laboratory of the University of Oulu in Finland. He is currently continuing his research towards a Ph.D. His research interests focus on low-voltage, low-power analog VLSI systems and ΔΣ modulators. Juha Kostamovaara received the degrees of Dipl. Eng, Licentiate of Tech. and Doctor of Tech. in electrical engineering in 1980, 1982 and 1987, respectively, all from the University of Oulu, Finland. He was Acting Associate Professor of Electronics in the Department of Electrical Engineering at the University of Oulu in 1987–1993, and was nominated Associate Professor from the beginning of 1993. During 1994 he worked as an Alexander von Humboldt Scholar at the Technical University of Darmstadt, Germany. In 1995 he was invited to become full Professor of Electronics at the University of Oulu, where he is currently also head of the Electronics Laboratory. Prof. Kostamovaara's main interest is in the development of high-speed electronic circuits and systems and their applications in electronic and optoelectronic measurements and radio mobile telecommunications. An erratum to this article can be found at     

Tomato powder impedes the development of azoxymethane‐induced colorectal cancer in rats through suppression of COX‐2 expression via NF‐κB and regulating Nrf2/HO‐1 pathway

Cancer is one of the leading causes of death worldwide. Since dietary factors have been connected to a reduced risk of a diversity of human cancers, in this study we investigated the effects of tomato powder (TP) on the development of azoxymethane (AOM)‐induced colorectal cancer in Wistar rats, and possible mechanism(s) by which TP shows its chemopreventive activity. Here we show that TP added to feed at 5% rate decreases the rate of aberrant crypt foci (ACF) and reduces the development of adenocarcinoma and growth of AOM‐induced colorectal cancer in rats. In addition, we demonstrate that TP supplementation shows its chemopreventive activities through inhibition of cyclooxygenase‐2 (COX‐2) expression via NF‐κB pathway and promotion of apoptosis, as well as regulating Nrf2/HO‐1 signaling pathway in colorectal tissue of AOM‐treated rats. Our findings identify an intimate connection between dietary supplementation of TP and the decreased risk of colorectal cancer in rats, and suggest that consumption of TP would be a natural candidate for the prevention of colorectal cancer in men.     

The physical,chemical,and microscopic properties of masonry mortars from Alhambra Palace (Spain) in reference to their earthquake resistance

Al-Andalus mortar is an ancient binding material (lime mortar) that was used for centuries in numerous historical buildings in Al-Andalus,Granada (Spain).The physico-chemical and microscopic properties of Al-Andalusmortars in Granada were studied as part of an investiga-tion into the mineral raw materials present in the territory of Spain.Scanning electron microscope and X-ray diffraction analyses of eight main types of mortars were performed to show the presence of calcite, gypsum, quartz, and muscovite minerals with organic fibers. Chemical analyses of the specimens showed that high SiO2+Al2O3+Fe2O3 contents yielded high values of hydraulicity and cementation indices. A significant result of this study was that mortars with high hydraulicity and cementation indices have high mechanical strengths.This characteristic may be the main reason for the earthquake resistance of the historical Alhambra Palace.