Seed layer effect on morphological,structural, and optical properties of electrochemically grown ZnO nanowires over different SnO2:F/glass substrates

Journal of Solid State Electrochemistry - Transparent conductive oxide electrodes and specifically SnO2:F/glass are widely employed substrates in the preparation of optoelectronic devices. This...     

Ultrasonic sensor to measure the density of a liquid or slurry during pipeline transport

This paper describes the design and testing of a computer-controlled sensor for the real-time measurement of the density of a liquid or slurry. It is to be deployed at the US Department of Energy's Hanford Site in Richland, WA, to monitor slurry properties during radioactive waste transfers. To demonstrate the sensor performance, tests were carried out using non-radioactive waste simulants and the results will be presented. The sensor is mounted flush with the pipeline wall in a nominal 5-cm (2-in.) pipe spool piece. The design pressure is 2.8 MPa (400 psi). The probe wedge in contact with the slurry was selected to operate up to pH 14, and the probe components were radiation tested at exposures of 1 x 10(6) R. The sensor is applicable for process control of all types of liquids or slurries in pipelines or in vessels.     

Statistical Inference for Partially Observed Markov-Modulated Diffusion Risk Model

We propose a method for obtaining the maximum likelihood estimators of the parameters of the Markov-Modulated Diffusion Risk Model in which the inter-claim times, the claim sizes, and the volatility diffusion process are influenced by an underlying Markov jump process. We consider cases when this process has been observed in two scenarios: first, only observing the inter-claim times and the claim sizes in an interval time, and second, considering the number of claims and the underlying Markov jump process at discrete times. In both cases, the data can be viewed as incomplete observations of a model with a tractable likelihood function, so we propose to use algorithms based on stochastic Expectation-Maximization algorithms to do the statistical inference. For the second scenario, we present a simulation study to estimate the ruin probability. Moreover, we apply the Markov-Modulated Diffusion Risk Model to fit a real dataset of motor insurance.

     

A framework for the automated real-time detection of short tonal sounds from ocean observatories

Acquisition of acoustic data from ocean observatories is expected to play a key role for the long-term monitoring of marine mammals and anthropogenic noise. It typically requires processing of a large volume of acoustic data and it must rely on automated identification of signals. We present an algorithmic framework for the detection of short tonal sounds (e.g. cetacean calls, anthropogenic pings) intended to act as a first stage in a system for the automated real-time detection, classification, and localisation of acoustic sources. The algorithm was validated under a diversity of scenarios expected at ocean observatories. Using simulated signals that emulate a variety of cetacean call-types, perfect identification of signal position was obtained for signal to noise ratios of ?15 to ?5 dB, depending on the signal-type. Separation of real-world data segments with short tonal sounds (mainly cetacean calls) from segments with other sounds or noise resulted in Area Under the ROC Curve values between 0.96 and 0.98. The algorithm can be used to automatically identify cetacean calls and anthropogenic short tonal sounds much faster than in real-time, thereby reducing the burden put on data transmission, storage, or processing by classification and localisation algorithms.     

Neutral bis­(ethyl­enedi­thio)­tetra­thia­fulvalene at 100 K

The low‐temperature crystal structure of bis­(ethyl­enedi­thio)­tetra­thia­fulvalene (BEDT‐TTF), C₁₀H₈S₈, is similar to its high‐temperature structure. The room‐temperature central bond lengths of this mol­ecule are often used as reference in empirical methods to estimate the charge carried by the (BEDT‐TTF)_xⁿ⁺ cations in the BEDT‐TTF mol­ecule‐based organic conductors. We show that the method we previously reported can still be used with low‐temperature BEDT‐TTF salts data. Moreover, we confirm the purely thermal origin of the ordering of the ethyl­ene group.     

1-Methylimidazolin-2-yl functionalized cyclopentadienyl complexes of titanium and zirconium. Crystal structure of {[η:η-κN-C5H4CPh2CH2-(1-Me-C3H4N2)]ZrCl2}2(μ-Cl)2

The novel bidentate ligand, C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3), has been prepared and characterized as its lithium salt LiC₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Li). Cyclopentadiene HC₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-H) has been obtained from 6,6-diphenylfulvene and 1,2-dimethylimidazoline (1). In THF-d₈ solution in the presence of 1, (1-methylimidazoline-2-yl)methyllithium (2) has been proved to undergo gradual conversion into a dilithium derivative of N¹-methyl-N²-[(1E,2E)-1-methyl-2-(1-methylimidazolidine-2-idene)ethylidene]ethane-1,2-diamine (2a). In a solution, cyclopentadiene 3-H has been shown to undergo isomerization into 3-{N-[2-(N-methylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene (4) and, further, into a mixture of 4 and two rotameric 3-[N-(2-aminoethyl)-N-methylamino]-1,1-diphenyl-1,2-dihydropentalenes (5a) and (5b). Treatment of the lithium salt 3-Li with Me₃SiCl has lead to 3-{N-[2-(N-trimethylsilylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene (6) as the dominant component in the reaction mixture. In the latter case the expected Me₃Si-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Si) was not observed. Stannylation of 3-Li with 1 equiv. of Me₃SnCl has resulted in formation of a mixture of Me₃Sn-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Sn), (Me₃Sn)₂-C₅H₃CPh₂CH₂-(1-Me-C₃H₄N₂) (3-Sn₂), and cyclopentadiene 3-H in a ca. 2:1:1 molar ratio. Monocyclopentadienyl complexes {[η⁵:η¹-κN-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂)]MCl₃ (M = Ti (7), Zr (8)) have been prepared starting from the organotin and organolithium compounds 3-Sn and 3-Li, respectively. The dynamic behavior of complexes 7 and 8 has been investigated by means of variable-temperature NMR spectroscopy in solutions. The molecular structures of the dihydropentalene 4, binuclear complex {[η⁵:η¹-κN-C₅H₄CPh₂CH₂-(1-Me-C₃H₄N₂)]ZrCl₂}₂(μ-Cl)₂8, and a coordination dimer of the dilithium salt 2a have been established by X-ray diffraction analysis. In the crystal structure of the 2a-dimer, the shortest known Li-Li contact has been found.     

Fluorolactonization of norbornenecarboxylic acids and their methyl esters with F-TEDA-BF4 and XeF2

The selective fluorolactonization was achieved by treatment of cis-5-norbornene-2,3-endo-dicarboxylic acid or its monomethyl and dimethyl esters with F-TEDA-BF₄ or XeF₂. The reactions of 5-norbornene-endo-2-carboxylic acid and its monomethyl ester with F-TEDA-BF₄ or XeF₂ proceed in a non-selective manner to give fluorolactonization, addition and rearrangement products. The basic factor responsible for selectivity of the fluorolactonization is the presence of two endo-oriented carboxyl groups in the substrate molecule. The electrophilicity and type of the fluorinating agent is of secondary importance in this regard. It is postulated that the fluorolactonization of norbornenecarboxylic acids and their methyl esters with F-TEDA-BF₄ or XeF₂ is realized mainly via “open” fluoronorbornyl carbocation intermediates which in the reaction with XeF₂ are postulated as the tight ion pairs.     

Silver(I) mediated folding of a molecular basket

We have investigated Ag(I) mediated folding of a tridentate compound, containing three pyridine flaps tethered to a semirigid scaffold, into a molecular basket, using both experimental and theoretical methods. The basket formation has been shown to be highly favorable in organic media (Delta G degrees = -7.2 kcal/mol), with the assembly process allowing for another ligand to bind preferentially on the outer side.     

Pinensins: The First Antifungal Lantibiotics

Lantibiotics (lanthionine‐containing antibiotics) from Gram‐positive bacteria typically exhibit activity against Gram‐positive bacteria. The activity and structure of pinensin A ( 1 ) and B ( 2 ), lantibiotics isolated from a native Gram‐negative producer Chitinophaga pinensis are described. Surprisingly, the pinensins were found to be highly active against many filamentous fungi and yeasts but show only weak antibacterial activity. To the best of our knowledge, lantibiotic fungicides have not been described before. An in‐depth bioinformatic analysis of the biosynthetic gene cluster established the ribosomal origin of these compounds and identified candidate genes encoding all of the enzymes required for post‐translational modification. Additional encoded functions enabled us to build up a hypothesis for the biosynthesis, export, sensing, and import of this intriguing lantibiotic.     

Selective Template Removal by Thermal Depolymerization to Obtain Mesostructured Molybdenum Oxycarbide

The carbon content of mesostructured organic‐inorganic hybrid material of a cylindrical block copolymer template of poly(2‐vinylpyridine)‐block‐poly(allyl methacrylate) (P2VP‐b‐PAMA) and ammonium paramolybdate (APM) could be reduced by thermal depolymerization. By calcination in vacuo at 320 °C the PAMA core can be completely removed while the remaining P2VP brush preserves the mesostructure. The P2VP‐APM composite can then be carburized in‐situ to MoO_xC_y in a second pyrolysis step without any additional carbon source but P2VP. The molybdenum oxycarbide nanotubes obtained, form hierarchically porous non‐woven structures, which were tested as catalyst in the decomposition of NH₃. They proved to be catalytically active at temperatures above 450 °C. The activation energy was estimated from an Arrhenius Plot to be 127 kJ · mol^–1.