Structure and property correlation for Ag deposition on alpha-Al2O3--a first principle study

The nature of bonding at the interface between deposited silver and (001) surface of alpha-Al2O3 for both Al-terminated and OH-terminated has been investigated using a periodic ab initio method. Substantial inter-planar relaxations within the alumina were found at both the interfaces and the bulk. The periodic calculation with Ag deposition shows that 10% of Ag loading on alumina results maximum stability. Now, this is known that, the clean alumina surface only exists at UHV condition and normally the alumina surface prefers to stay hydroxylated. We have therefore compared the silver bonding over hydroxylated alumina surface and confirmed the fact that the hydroxylated surface binds silver weakly in comparison to the clean surface and it recommends that the silver cluster over the hydroxylated surface begins to join in to form three-dimensional nuclei. The deposited Ag forms a cluster on top of the alumina surface. The Ag atomic packing was monitored to rationalize the role of packing on activity of silver. Three low-index Ag surfaces (100), (110) and (111) are investigated via the ab initio density functional calculations with ultrasoft potentials. We have monitored the relation between Ag atomic packing and its electronic properties. The results show that the structural and electronic property of Ag deposited on alumina surface depends significantly on atomic packing. Ag110 over clean alumina surface shows highest surface energy and smallest work function, whereas for the OH-terminated surface it is the Ag111. The results are discussed in view of the existing experimental data and models of metal-oxide interface.     

Catalytic roles of iron and hydrogen sulphide on hydrogenation of coal

Washed Samla coal was hydrogenated in batches, with and without added sulphur in the presence and absence of hydrated iron oxide as a catalyst, for 3 h at 400 °C under 21.6 MPa hydrogen pressure. Further, hydrogenation of the same coal was studied with varying amounts of hydrated iron oxide in the presence of tar oil as vehicle, keeping the quantity of added sulphur unaltered, at 450 °C under 24.5 MPa pressure for 1.5 h. Comparative roles of iron and H₂S in the catalytic hydrogenation of coal are suggested from the experimental results.     

Anion distribution in alkaline silicates

Alkaline sodium silicates have been prepared by heating sodium carbonate and silica mixtures in the mole ratio of 2.51.The silicates have been examined by chronopotentiometric and thermogravimetric methods. The electro-analytical technique has allowed the identification of the oxy-anions SiO₄ ^4–, Si₂O₇ ^6– and Si₃O₁₀ ^8– by their electro-reduction at cathodic potentials with reference to a graphite anode of approximately –1.0, –1.6, –2.0 V respectively.     

Factors responsible for the activity of precipitated iron fischer-tropsch catalysts

Three precipitated iron Fischer-Tropsch catalysts of identical chemical composition but prepared from different source materials were studied by gas adsorption. Of the Hofer ‘inducted’ catalysts, the most active one was found to combine greater surface area with a preponderance of narrower pores, compared with the other two. The greater activity was found to be reflected in the ‘a’ factor (Elovich Equation) which was very large. The limitation of the energy of activation as a parameter for the activity of solid heterogeneous catalyst was illustrated in terms of ‘compensation effect’. The complex nature of adsorption kinetics was shown by the anomalous temperature dependence of ‘a’ as well as changes in the slope of q versus log t curves.     

Observations on the effect of post-weld heat treatment on J-resistance curves of sa-106b seamless piping welds

Ontario Hydro has developed a leak-before-break (LBB) methodology for application to large diameter piping (21, 22 and 24 inch) Schedule 100 SA106B heat transport (HT) piping as a design alternative to pipe whip restraints and in recognition of the questionable benefits of providing such devices. Ontario Hydro's LBB approach uses elastic-plastic fracture mechanics (EPFM).In order to assess the stability of HT piping in the presence of hypothetical flaws, the value of the material J-integral associated with crack extension (J— R curve) must be known. In a material test program J-resistance curves were determined from various pipe heats and four different welding procedures that were developed by Ontario Hydro for nuclear Class 1 piping. The test program was designed to investigate and quantify the effect of various factors such as test temperature, crack plane orientation and welding effects which have an influence on fracture properties. An acceptable lower bound J-resistance curve for the piping steels and welds were obtained by machining maximum thickness specimens from the pipes and weldments and by testing side-grooved compact tension specimens. This paper addresses the effect of test temperature and post-weld heat treatment on the J-resistance curves from the welds.The fracture toughness of all the welds at 250°C was lower than that at 20°C. Welds that were post-weld heat treated showed high crack initiation toughness, J_lc, rising J-resistance curves and stable and ductible crack extension. Non post-weld heat treated welds, while remaining tough and ductile, showed comparatively lower J_Ic, and J-resistance curves at 250°C. This drop in toughness is possibly due to a dynamic strain aging mechanism evidenced by serrated load-displacement curves. The fracture toughness of non post-weld heat treated welds increased significantly after a comparable post-weld heat treatment.The test procedure was validated by comparing three test results against independent tests conducted by Materials Engineering Associates (MEA) of Lanham, Maryland. The J_Ic and J-resistance curves obtained by Ontario Hydro and MEA were comparable.     

The Role of Leaf Volatiles of <Emphasis Type="Italic">Ludwigia octovalvis</Emphasis> (Jacq.) Raven in the Attraction of <Emphasis Type="Italic">Altica cyanea</Emphasis> (Weber) (Coleoptera: Chrysomelidae)

Larvae and adults of Altica cyanea (Weber) (Coleoptera: Chrysomelidae) feed on the rice-field weed Ludwigia octovalvis (Jacq.) Raven (Onagraceae), commonly known as willow primrose, which is considered a biocontrol agent of the weed. Volatile organic compounds from undamaged plants, plants after 4, 12, and 36 h of continuous feeding by A. cyanea larvae or adult females and after mechanical damaging were identified by GC-MS and GC-FID analyses. Twenty nine compounds were identified from undamaged plants. 2Z–Penten-1-ol, geraniol, and 1-tridecanol were present in all plants damaged by larvae. In contrast, feeding by adults caused the release of 2Z–penten-1-ol only after 12 and 36 h; whereas geraniol and 1-tridecanol appeared only after 36 h. Farnesyl acetone was detected after 12 and 36 h of feeding by larvae and after 36 h of feeding by adults. Farnesene was detected after 36 h of feeding by larvae and adults. Linalool was unique after 36 h of feeding by larvae. In Y-shaped glass tube olfactometer bioassays, A. cyanea females were attracted to volatiles after 36 h of feeding by larvae or adults compared to volatiles released by undamaged plants. The insects were attracted to five synthetic compounds: 3-hexanol, α-pinene, linalool oxide, geraniol, and phytol. Synthetic blends were more attractive than individual compounds. Compared to undamaged plants, volatiles released by plants, damaged by conspecific individuals, were more attractive to A. cyanea females, due to elevated emissions of 3-hexanol, α-pinene, linalool oxide, geraniol, and phytol.     

Synthesis,characterization and investigation of proton exchange properties of sulfonated polytriazoles from a new semifluorinated diazide monomer

This work describes the synthesis and characterization of a new series of semifluorinated sulfonated polytriazole copolymers (PTATSH‐XX) with varying degree of sulfonation and higher IEC. The copolymers have been prepared by click reaction using a combination of diazide monomers; a newly synthesized diazide monomer namely 4,4‐bis[3‐trifluoromethyl‐4(4‐azidophenoxy)phenyl]benzene (TAZ) and a commercially available diazide monomer namely 4,4′‐diazido‐2,2′‐stilbenedisulfonic acid disodium salt (DADSDB) with a bis‐alkyne monomer namely 4,4′‐(propane‐2,2‐diyl)bis((prop‐2‐ynyloxy)benzene) (BPEBPA). The copolymers are well characterized by FTIR and NMR spectroscopy and have exhibited good solubility and film forming abilities along with good thermal and chemical stability, low water uptake, good dimensional stability and high mechanical properties. The TEM micrographs of the copolymer membranes show good phase separated morphology with cluster size in the range 10–60 nm. The proton conductivity values of the copolymer membranes are found in the range of 15–90 mS cm^?1 at 80°C and 16–97 mS cm^?1 at 90°C. POLYM. ENG. SCI., 57:312–323, 2017. © 2016 Society of Plastics Engineers     

Copolymers from methyl methacrylate and butyl acrylate with hyperbranched architecture

This is a first report of the synthesis and characterization of acrylic copolymers from methyl methacrylate (MMA) and butyl acrylate (BA) with hyperbranched architecture. The copolymers were synthesized using a free radical polymerization (Strathclyde method) in emulsion technique. Divinyl benzene was used as the brancher which acted as a comonomer and 1‐dodecanethiol was used as a chain terminating agent. A linear copolymer from MMA and BA was also synthesized for comparison. The hyperbranched architecture was established from spectroscopic and rheological measurements. The gel permeation chromatography showed all hyperbranched copolymers were low molecular weight with lower polydispersity index (PDI) ( 23,000, PDI ～ 2.00) compared to the linear grade ( 93,000, PDI ～ 2.20). They were more spherical and achieved lower viscosity (yet higher solubility, >90%) than the linear grade (<50%) which was mostly open ended. Lower viscosity at equivalent solid content made the hyperbranched polymers a potential binder for adhesive and coating application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45356.