Base alumina ceramics with dispersoids: mechanical behaviour and tissue response afterin vivo implantation

Base alumina ceramics with dispersoids (BAC) are a new class of ceramics with improved mechanical properties as compared to pure alumina. They are obtained by dispersion of powder within an alumina matrix. Of the three new ceramics studied here, A20Z possesses the best mechanical properties as well as tribological properties superior to those of pure alumina whether it is used in ceramic-ceramic or ceramic-polyethylene combination.Mechanical behaviour and tissue response afterin vivo implantation were studied. Small four-point flexion bars obtained by pressureless sintering were implanted subcutaneously in the rat. The mechanical properties were unmodified even after one year from implantation.The tissue response was studied up to one year on cylinders implanted in the paravertebral muscles of Wistar rats, and was evaluated by qualitative examination of the encapsulating membrane and measurement of its thickness in relation to pure alumina. The tissue responses were comparable for both alumina and the three tested ceramics.     

Partial oxidation of methane towards hydrogen production over a promising class of catalysts: Rh supported on Ti-modified MgO

The partial oxidation of methane over the supported Rh (0.8 wt.%) catalysts was investigated. Two kinds of supports were used, MgO and Ti-modified MgO (prepared by grafting technique). Among the Ti-modified MgO supports, two different compounds were used as source of Ti: inorganic (chloride) and organic (alkoxide). The catalytic performance of Rh-supported catalysts depends on the support and varies in the sequence: Ti-MgO/I > Ti-MgO/O > MgO. Ti-containing catalysts exhibited higher activity and selectivity compared to MgO, which is especially noticeable at low temperature. Possible explanations for the phenomena observed were proposed on the basis of characterization results.     

An Alternative Method for the Incorporation of Silver in Ag-VOx/TiO2 Catalysts for the Total Oxidation of Benzene

An alternative way of synthesis, the “onion” method, was used to deposit silver nanoparticles on a VO_x/TiO₂ catalyst. This synthesis method consists in the impregnation of organic vesicles containing the metallic silver nanoparticles. In situ calcination is needed to remove the organic vesicles and to offer an access of the reactants to the silver nanoparticles. This removal is easier in presence of vanadium. The addition of silver induces a higher proportion of V⁵⁺. The Ag-VO_x/TiO₂ catalysts prepared with this method exhibit better performances in the total oxidation of benzene after moderate in situ calcination at 350 °C than at 450 °C. A synergy between silver and vanadium is evidenced after both kinds of calcination with a silver loading of 0.125 and 0.25 wt%. The extent of this synergy is higher after a moderate calcination. This effect is likely due to the fact that small nanoparticles prepared via the “onions” sinter less after in situ calcination at 350 °C than at 450 °C. A clear link between the extent of the synergy and the size of the silver nanoparticles is evidenced. A decrease of the nanoparticle size induces a higher extent for the synergy.     

Three-dimensional analysis of boreholes considering spatial variability of properties and poroelastoplasticity

In general, analysis of oil producing wells is carried out considering that both hydraulic and mechanical parameters of the rock mass are deterministic. Mechanical and hydraulic properties of rock masses and in particular sedimentary rock masses may show a considerable degree of spatial variability. This paper focuses on the evaluation of the three-dimensional borehole response, particularly of the plastic zone, taking into account the spatial variability of both hydraulic and mechanical properties. The analysis is performed with a developed finite element program that incorporates spatial variability, coupled fluid-mechanical effects and elastoplastic behavior of the rock mass. Examples are shown and conclusions are drawn regarding the effect of spatial variability on the three-dimensional borehole analysis.     

Decentralised event-triggered cooperative control with limited communication

This note studies event-triggered control of Multi-Agent Systems (MAS) with first-order integrator dynamics. It extends previous work on event-triggered consensus by considering limited communication capabilities through strict peer-to-peer non-continuous information exchange. The approach provides both a decentralised control law and a decentralised communication policy. Communication events require no global information and are based only on local state errors; agents do not require a global sampling period or synchronous broadcasting as in sampled-data approaches. The proposed decentralised event-triggered control technique guarantees that the inter-event times for each agent are strictly positive. Finally, the ideas in this note are used to consider the practical scenario where agents are able to exchange only quantised measurements of their states.     

Evaluation of Antioxidant,Antidiabetic and Anticholinesterase Activities of Smallanthus sonchifolius Landraces and Correlation with Their Phytochemical Profiles

The present study aimed to investigate the phytochemical profile of leaf methanol extracts of fourteen Smallanthus sonchifolius (yacon) landraces and their antioxidant, anticholinesterase and antidiabetic activities that could lead to the finding of more effective agents for the treatment and management of Alzheimer’s disease and diabetes. For this purpose, antioxidant activity was assessed using different tests: ferric reducing ability power (FRAP), 2,2-diphenyl-1-picryl hydrazyl (DPPH), nitric oxide (˙NO) and superoxide (O₂˙⁻) scavenging and lipid peroxidation inhibition assays. Anticholinesterase activity was investigated by quantifying the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, whereas antidiabetic activity was investigated by α-amylase and α-glucosidase inhibition tests. To understand the contribution of metabolites, phytochemical screening was also performed by high performance liquid chromatography-diode array detector (HPLC-DAD) system. Among all, methanol extract of PER09, PER04 and ECU44 landraces exhibited the highest relative antioxidant capacity index (RACI). ECU44 was found to be rich in 4,5-di-O-caffeoylquinic acid (CQA) and 3,5-di-O-CQA and displayed a good α-amylase and α-glucosidase inhibition, showing the lowest IC₅₀ values. Flavonoids, instead, seem to be involved in the AChE and BChE inhibition. The results of this study revealed that the bioactive compound content differences could be determinant for the medicinal properties of this plant especially for antioxidant and antidiabetic activities.     

Nitrogen solubility in CaO-CaF2-SiO2 melts

The preceding paper^[5] demonstrated that nitrogen dissolves in silicate melts either as a free ion or complex anion, being incorporated into silicate networks. In the present study, the influence of CaF₂ addition to CaO-SiO₂ melts on the nitrogen solubility was investigated along the liquidus at 1573 K and within the liquidus at 1723 K at constant CaF₂ levels. In the latter case, as the SiO₂ content increases from CaO saturation, the total nitrogen content decreases to reach the minimum and then starts to increase up to the SiO₂ saturation. This is in accord with the abovementioned mechanism of nitrogen dissolution, which is supported by the changing behavior of free and incorporated nitrogen contents with the slag composition. The role of CaF₂ is complicated through the formation of fluorosilicates. The CaF₂ seems not to function simply as a diluent but to enhance the dissolution of nitrogen by releasing oxygen from silicate networks, promoting the formation of free nitride ions. Formerly Graduate Student, Department of Metallurgy, The University of Tokyo.     

Automatic searching and evaluation of priority and emerging contaminants in wastewater and river water by stir bar sorptive extraction followed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

A new analytical method based on stir bar sorptive extraction (SBSE), followed by comprehensive two-dimensional gas chromatography (GCxGC-TOF-MS), has been developed for the automatic searching and evaluation of nonpolar or semipolar contaminants in wastewater and river water. The target compounds selected were 13 personal care products (PCPs), 15 polycyclic aromatic hydrocarbons (PAHs) and 27 pesticides. Excellent results have been obtained in terms of separation efficiency and also in terms of compound identification. Exceptional method detection limits were achieved applying the optimized method, at or below 1 ng/L for most of the compounds in real samples. The reliable confirmation of analyte identity was possible at this low concentration level, even for typically troublesome compounds such as the PAHs. The other validation parameters were good. In addition to obtaining analytical information such as identification and quantification of target analytes, it is also possible to screen for nontarget compounds or unknowns. New contaminants have been identified in the wastewater effluents and river water samples, such as cholesterol and its degradation products, pharmaceuticals, industrial products, other pesticides, and PCPs. The multidimensional information generated by the instrument can also be used by the researchers for contrasting samples and identifying, much more easily, the major differences between samples. We have used this feature to propose studies of comparison between the fingerprinting of different water samples, such as the contamination variation along a river affected by the discharge of urban wastewaters and also the contamination variation over a period of time in the effluent. Results show that the most frequently detected contaminants (and the contaminants detected at higher concentrations) were the PCPs. The musk fragrances galaxolide and tonalid were the most concentrated compounds in the samples. The pesticides and PAHs were present at much lower concentration than PCPs.