Precipitation during homogenization cooling in AlMgSi alloys

Precipitation during the industrial cool down takes place predominantly above 300 °C in the EN AW-6082 and 6005 alloys. The phase precipitation throughout cooling is equilibrium β phase. A considerable capacity is retained after the cool down for further precipitation during a subsequent heating cycle. The β-Mg₂Si is once again the predominant phase that forms during a scan heating cycle employed in exactly the same manner with the industrial billet preheating operation. The precipitation in the 6060 alloy, on the other hand, occurs predominantly below 300 °C with additionally β′-Mg₂Si particles formed below 200 °C.     

Upgrading poly(styrene-co-divinylbenzene) beads: Incorporation of organomodified metal-free semiconductor graphitic carbon nitride through suspension photopolymerization to generate photoactive resins

The inclusion of the metal free semiconductor graphitic carbon nitride (g-CN) into polymer systems brings a variety of new options, for instance as a heterogeneous photoredox polymer initiator. In this context, we present here the decoration of the inner surface of poly(styrene-co-divinylbenzene) beads with organomodified g-CN via one pot suspension photopolymerization. The resulting beads are varied by changing reaction parameters, such as, crosslinking ratio, presence of porogens, and mechanical agitation. The photocatalytic activity of so-formed beads was tested by aqueous rhodamine B dye photodegradation experiments. Additionally, dye adsorption/desorption properties were examined in aqueous as well as in organic solvents. Photoinduced surface modification with vinylsulfonic acid and 4-vinyl pyridine is introduced. Overall, metal-free semiconductor g-CN donates photoactivity to polymer networks that can be employed for dye photodegradation and acid–base catalyst transformation through facile photoinduced surface modifications.     

Understanding the Potential In Vitro Modes of Action of Bis(β-diketonato) Oxovanadium(IV) Complexes

To understand the potential in vitro modes of action of bis(β-diketonato) oxovanadium(IV) complexes, nine compounds of varying functionality have been screened using a range of biological techniques. The antiproliferative activity against a range of cancerous and normal cell lines has been determined, and show these complexes are particularly sensitive against the lung carcinoma cell line, A549. Annexin V (apoptosis) and Caspase-3/7 assays were studied to confirm these complexes induce programmed cell death. While gel electrophoresis was used to determine DNA cleavage activity and production of reactive oxygen species (ROS), the Comet assay was used to determine induced genomic DNA damage. Additionally, Förster resonance energy transfer (FRET)-based DNA melting and fluorescent intercalation displacement assays have been used to determine the interaction of the complexes with double strand (DS) DNA and to establish preferential DNA base-pair binding (AT versus GC).     

Effects of cavity disinfectants on bond strength of an etch-and-rinse adhesive to water- or ethanol-saturated sound and caries-affected dentin

Objective: To evaluate the effect of cavity disinfectants on the immediate microtensile bond strength (μTBS) of an etch-and-rinse adhesive to water- and ethanol-saturated sound and caries-affected dentin (CAD). Material and Methods: Thirty-six human molars were sectioned to expose 1/3 of the mid-coronal dentin surface. Sound (n = 18) and CAD (n = 18) specimens were divided into six groups each (n = 3): one positive control (sound), one negative control (CAD), and five experimental groups each. In the control group, dentin surfaces were bonded using an etch-and-rinse adhesive with a traditional water-wet bonding technique. In the experimental groups, ozone was applied before etching and chlorhexidine after etching. In the ethanol-wet bonding groups, acid-etched dentin surfaces were treated with ethanol. Following adhesive application and composite buildups, bonded specimens were sectioned to form sticks. Failure modes were analyzed using a stereomicroscope. Results: The water-wet bonded sound control group yielded the highest μTBS among all groups (p < 0.001). The lowest μTBS values were observed in the ozone groups (p < 0.05). The ethanol-wet bonded CAD group exhibited a higher μTBS than the water-wet bonded negative controls. Although compared to the positive control, chlorhexidine decreased the μTBS (p < 0.05), an increase with no significant difference was observed in the negative control (p > 0.05). Conclusions: The μTBS values of CAD were lower than those of sound dentin. Ethanol-wet bonding improved the μTBS of CAD. Ozone application reduced the μTBS in both sound and CAD; chlorhexidine improved the immediate μTBS after etching in CAD.     

Effect of CeO2 addition on densification and microstructure of Al2O3-YSZ composites

Alumina (Al₂O₃) and alumina-yttria stabilized zirconia (YSZ) composites containing 3 and 5 mass% ceria (CeO₂) were prepared by spark plasma sintering (SPS) at temperatures of 1350-1400 °C for 300 s under a pressure of 40 MPa. Densification, microstructure and mechanical properties of the Al₂O₃ based composites were investigated. Fully dense composites with a relative density of approximately 99% were obtained. The grain growth of alumina was inhibited significantly by the addition of 10 vol% zirconia, and formation of elongated CeAl₁₁O₁₈ grains was observed in the ceria containing composites sintered at 1400 °C. Al₂O₃-YSZ composites without CeO₂ had higher hardness than monolithic Al₂O₃ sintered body and the hardness of Al₂O₃-YSZ composites decreased from 20.3 GPa to 18.5 GPa when the content of ZrO₂ increased from 10 to 30 vol%. The fracture toughness of Al₂O₃ increased from 2.8 MPa m^1/2 to 5.6 MPa m^1/2 with the addition of 10 vol% YSZ, and further addition resulted in higher fracture toughness values. The highest value of fracture toughness, 6.2 MPa m^1/2, was achieved with the addition of 30 vol% YSZ.     

Diffusion coefficients and phase equilibria of carbon dioxide–ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) system

This article presents the mutual diffusion coefficients of a carbon dioxide–ionic liquid, [bmim][PF₆], system at temperatures of 313.15 and 323.15 K and pressures of 5 and 8 MPa. In order to estimate the diffusion coefficients, we have carried out experiments to find time-dependent carbon dioxide solubilities in the ionic liquid and then fit a transport model to the data. In a system containing high pressure carbon dioxide and ionic liquid, carbon dioxide dissolves in the liquid until its equilibrium mole fraction is reached. During this process, the position of the liquid–vapour interface and the density of the liquid phase change. To account for the variation in liquid density, an equation fit to the experimental density data is included in the transport model. To track the moving interface, the volume-of-fluid method is used. The diffusivities at dilute concentration and at thermodynamic phase equilibrium are determined and compared with the literature values and those obtained from correlations.     

Physical and mechanical properties of materials prepared using Class C fly ash and soybean oil

In present work; epoxidized soybean oil (ESO), fly ash (FA) and natural clay (C) are used to produce 45 kinds of biocomposite materials and by analyzing the physical–mechanical properties of these novel materials, their use as an insulation material is investigated. The compressive strength, tensile strength, abrasion loss, thermal conductivity and oven-dry mass of each sample are measured. The minimum thermal conductivity of 0.273 W/mK is observed with the samples containing ESO–FA–C. It is increased with the decrease of ESO and FA. The compressive and tensile strengths are varied from 13.53 to 6.31 MPa and 1.287 to 0.879 MPa, respectively.     

盐胁迫环境下腐植酸类物质对小麦生长及矿物营养吸收的影响

对在不同浓度的盐胁迫条件下,叶面喷施液态腐植酸和土壤施用腐植酸类物质对小麦作物生长和矿物营养吸收的影响进行了研究。通过添加不同量的NaCl得到不同的盐浓度环境。腐植酸类物质在作物种植前一个月施用,液态腐植酸在种苗发芽后20d和35d喷施于小麦叶面。腐植酸类物质的施用量为0、1g/kg、2g/kg,液态腐植酸的浓度为0、0.1%、0.2%。盐度对小麦生长具有负面影响,它会降低小麦对除Na、Mn以外的矿物营养的吸收,影响小麦干重。通过在土壤施用腐植酸类物质可以增加小麦对N的吸收,叶面施用腐植酸可增加其对P、K、Mg、Na、Cu和Zn的吸收。研究结果显示：在土壤中施用腐植酸类物质,不同盐浓度与施用量之间存在较好的相关性,但叶面喷施时盐度和喷施量之间相关性并不明显。在盐胁迫环境的影响下,叶面喷施腐植酸的初始浓度和土壤中施用的腐植酸类物质的初施量都增加了作物对营养元素的吸收。     

Synthesis of poly(epichlorohydrin‐g‐methyl methacrylate) and poly(epichlorohydrin‐g‐styrene) graft copolymers by a combination of cationic and photopolymerization methods

Poly(epichlorohydrin‐g‐styrene) and poly (epichlorohydrin‐g‐methyl methacrylate) graft copolymers were synthesized by a combination of cationic and photoinitiated free‐radical polymerization. For this purpose, first, epichlorohydrin was polymerized with tetrafluoroboric acid (HBF₄) via a cationic ring‐opening mechanism, and, then, polyepichlorohydrin (PECH) was reacted ethyl‐hydroxymethyl dithio sodium carbamate to obtain a macrophotoinitiator. PECH, possessing photolabile thiuram disulfide groups, was used in the photoinduced polymerization of styrene or methyl methacrylate to yield the graft copolymers. The graft copolymers were characterized by ¹H‐NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatography. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008