Gaseous corrosion mechanisms of silicon carbides in Na2SO4 and V2O5 environments

Hot-pressed polycrystalline SiC (HPSiC) and single crystal SiC (SCSiC) were exposed to Na₂SO₄ and V₂O₅ vapours at 1000 °C. Vapours were carried by the argon gas over the specimens where corrosion studies were conducted. Mixed-kinetics mechanisms for HPSiC under gaseous environments have been developed in the form of corrosion weight loss per unit area with time. The decomposed gases diffusing through the SiO₂ film and the reaction products at the substrate surfaces are the two major steps that contribute to the overall reaction for this material. SCSiC was observed to have severe corrosion attacks on its surfaces and corrosion pits with honeycomb shapes were left.     

Current approaches to punctuation in computational linguistics

Some recent studies in computational linguistics have aimed to take advantage of various cues presented by punctuation marks. This short survey is intended to summarise these research efforts and additionally, to outline a current perspective for the usage and functions of punctuation marks. We conclude by presenting an information-based framework for punctuation, influenced by treatments of several related phenomena in computational linguistics.Varol Akman is a professor of computer engineering at Bilkent University, Ankara, Turkey. From 1980 to 1985, he was a Fulbright scholar at Rensselaer Polytechnic Institute, Troy, New York, where he received a PhD degree in computer engineering. Prior to joining Bilkent in 1988, he held a senior researcher position with the Centrum voor Wiskunde en Informatica, Amsterdam, the Netherlands. His current research areas include artificial intelligence models of context, computational aspects of situation theory, and in general, language and philosophy.Abbreviations DRT discourse representation theory - DRS discourse representation structure - NLP natural language processing - NLG natural language generation - RST rhetorical structure theory - SDRT segmented discourse representation theory - SDRS segmented discourse representation structure Bilge Say received her BS in Computer Engineering from Middle East Technical University, Ankara, Turkey, in 1990, and her MS in Computation from Oxford University, Oxford, UK, in 1991. She worked two years as a systems support engineer in the industry. Currently, she is a PhD student at Bilkent University, Ankara, Turkey, studying the information-based aspects of punctuation. She has recently conducted research at the Computer Lab of Cambridge University, Cambridge, UK, on an extended visit.     

Controlled size and morphology of EDTMP-doped hydroxyapatite nanoparticles as model for <Superscript>153</Superscript>Samarium-EDTMP doping

Hydroxyapatite (HA) nanoparticles have been studied as nano-sized carriers for the delivery of therapeutic agents. One important consideration for these carriers to be used effectively is their bio-distribution in vivo, of which particle size has a significant effect. In this work, HA nanoparticles doped with Ethylene-diamine-tetramethylene-phosphonate (EDTMP) were synthesized via co-precipitation as a model for HA doped with (153)Samarium ((153)Sm) EDTMP. EDTMP has high affinity for radioactive (153)Sm isotopes that can emit both gamma and beta radiation. The effects of synthesis temperature, amount of dopant and hydrothermal treatment on the size of HA-EDTMP nanoparticles were therefore studied. The results showed that the EDTMP ligand was successfully incorporated in the nanoparticles without changing the crystal structure as shown from X-ray diffractometer (XRD) analysis. From the Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) micrographs, it was observed that shorter rod-like nanoparticles, obtained at low synthesis temperatures, became elongated needle-like nanoparticles with increasing temperature. Increasing dopant amount by five fold increases particle size slightly, while a two fold increase in dopant amount has no significant effect. Hydrothermal treatment increases particle crystallinity and results in smooth elongated rod-like structures. The size of HA nanoparticles doped with EDTMP can therefore be manipulated by controlling synthesis temperature and through hydrothermal treatment.     

Influence of germination period on physicochemical,pasting and antioxidant properties of Indian wheat cultivars

In the present study, physicochemical, pasting and antioxidant properties of six wheat (Triticum aestivum L.) cultivar grains after 24, 48 and 72 h of germination duration were evaluated and compared with their un-germinated counterparts. Chemical compositions of un-germinated fraction of whole flour were also determined. The results showed that swelling power decreased whereas solubility increased as the time of germination increased. From 24 to 72 h water and oil absorption capacities increased significantly with germination. The DPPH radical scavenging activity and reducing power exhibited significant (p?≤?0.05) increase with germination for all the cultivars. Total phenolic content ranged from 463.6 to 644.6 µg ferulic acid equivalents (FAE)/g for un-germinated to 1255.5–2380.9 µg FAE/g for germinated whole grain flour. Total flavonoids content increased from 86.5 to 266.7 µg catechin equivalents (CE)/g for un-germinated to 289.7–385.4 µg CE/g as the duration of germination increased from 0 to 72 h. The characteristics curves showing pasting profile of different cultivars became nearly linear for 48 and 72 h germinated grain flour. Several, significant correlations were observed among studied properties from principal component analysis.     

Cr(III)-imprinted polymeric beads: Sorption and preconcentration studies

The purpose of this study is to prepare a novel molecular imprinted adsorbent to Cr(III) analysis with high selectivity. Initially, chromium (III)-methacryloylhistidine (MAH/Cr(III)) complex monomer was synthesized and then Cr(III) ion imprinted ethyleneglycoldimethacrylate-methacryloylhistidine (poly(EDMA-MAH/Cr(III))) was polymerized. Cr(III) ions were removed from the Cr(III)-imprinting polymer. Selective cavity for the chromium (III) ions was obtained in the (poly(EDMA-MAH/Cr(III))) beads. These Cr(III)-imprinted beads were used in the sorption-desorption process. The effect of initial concentration of metal, the sorption rate and the pH of the medium on sorption capacity of Cr(III)-imprinting sorbents were studied. Sorption equilibrium time was achieved in about 30min. The maximum sorption of Cr(III) ions onto imprinted beads was about 69.28mg/g. Sorption studies of Co(II), Ni(II), Cr(III) and Cr(VI) ions were also investigated using Cr(III)-imprinting polymers. The obtained results show that selectively adsorbed amount of Cr(III) ion on Cr(III)-imprinting polymers is higher than all other studied ions. When the beads were used repeatedly, their adsorption capacity was showed feasibility.     

4-Aminophenyl boronic acid modified gold platforms for influenza diagnosis

As a potential pandemic threat to human health, there has been an urgent need for rapid, sensitive, simpler and less expensive detection method for the highly pathogenic influenza A virus. For this purpose, Quartz Crystal Microbalance (QCM) and Surface Plasmon Resonance (SPR) sensors have been developed for the recognition of hemagglutinin (HA) which is a major protein of influenza A virus. 4-Aminophenyl boronic acid (4-APBA) has been synthesized and used as a new ligand for binding of sialic acid (SA) via boronic acid–sugar interaction. SA has an important role in binding of HA. QCM and SPR sensor surfaces have been modified with thiol groups and then 4-APBA and SA have been immobilized on sensor surfaces, respectively. Sensor surfaces have been screened with AFM and used for the determination of HA from aqueous solution. The selective recognition of the QCM and SPR sensors toward Concanavalin A has been reported in this work. Also, the binding capacity and detection limits of QCM and SPR sensors have been calculated and detection limits were found to be 4.7 × 10^? 2 μM, (0.26 μg ml^? 1) and 1.28 × 10^? 1 μM, (0.72 μg ml^? 1) in the 95% confidence interval, respectively.     

Enhanced Sulfur Tolerance of Ceria-Promoted NO x Storage Reduction (NSR) Catalysts: Sulfur Uptake, Thermal Regeneration and Reduction with H2(g)

SO _x uptake, thermal regeneration and the reduction of SO _x via H₂(g) over ceria-promoted NSR catalysts were investigated. Sulfur poisoning and desulfation pathways of the complex BaO/Pt/CeO₂/Al₂O₃ NSR system was investigated using a systematic approach where the functional sub-components such as Al₂O₃, CeO₂/Al₂O₃, BaO/Al₂O₃, BaO/CeO₂/Al₂O₃, and BaO/Pt/Al₂O₃ were studied in a comparative fashion. Incorporation of ceria significantly increases the S-uptake of Al₂O₃ and BaO/Al₂O₃ under both moderate and extreme S-poisoning conditions. Under moderate S-poisoning conditions, Pt sites seem to be the critical species for SO _x oxidation and SO _x storage, where BaO/Pt/Al₂O₃ and BaO/Pt/CeO₂/Al₂O₃ catalysts reveal a comparable extent of sulfation. After extreme S-poisoning due to the deactivation of most of the Pt sites, ceria domains are the main SO _x storage sites on the BaO/Pt/CeO₂/Al₂O₃ surface. Thus, under these conditions, BaO/Pt/CeO₂/Al₂O₃ surface stores more sulfur than that of BaO/Pt/Al₂O₃. BaO/Pt/CeO₂/Al₂O₃ reveals a significantly improved thermal regeneration behavior in vacuum with respect to the conventional BaO/Pt/Al₂O₃ catalyst. Ceria promotion remarkably enhances the SO _x reduction with H₂(g).     

Metallurgical principles of cryogenically treated tool steels��a review on the current state of science

The cryogenic treatment of tool steels has transformed over centuries from black art to science, but the metallurgical principles responsible for increase in wear resistance, tensile strength, toughness, and stability are still disputed. Metallurgists comprehend how tool steels respond to cryogenic treatment, but they also understand that for many years, the cryogenic treatment of tool steels had the reputation of being a quick fix for poor heat treatment practice. During the cryogenic treatment of tool steels, the process modifies the carbon present in the tool steels. However, cryogenic treatment has not been widely adopted by the cutting tools industry due to lack of understanding of the fundamental metallurgical mechanisms and due to the wide variation in reported research findings. In the present paper, an attempt has been made to review the literature on metallurgical changes that occurred during the cryogenic treatment of tool steels to benefit the cutting tools industry. The prominent reasons found to be responsible for improving the mechanical properties of tool steels are transformation of retained austenite to martensite and precipitation of fine carbides.