Catalytic olefin epoxidation with cationic molybdenum(VI) cis-dioxo complexes and ionic liquids

The complexes [MoO₂Cl(HC(bim)₃)]Y (Y = Cl (1), BF₄ (2) and PF₆ (3)) have been prepared by reaction of MoO₂Cl₂(THF)₂ (for 1) or [MoO₂Cl(THF)₃]Y (for 2 and 3) with the tridentate ligand HC(bim)₃ = tris(benzimidazolyl)methane, and characterized by IR and Raman spectroscopy, and ¹H NMR. The turnover frequencies for the epoxidation of cis-cyclooctene at 55 °C with tert-butyl hydroperoxide (TBHP, in decane) as the oxidant and complexes 1–3 as catalysts are in the range of 70–200 mol mol_Mo^?1 h^?1. 1,2-Epoxycyclooctane is always the only reaction product for reaction times up to 24 h. With the aim of facilitating the recyclability of the complexes, the ionic liquids (ILs) [BMIM]Y and [BMPy]Y (BMIM = 1-n-butyl-3-methylimidazolium, BMPy = 1-n-butyl-3-methylpyridinium; Y = BF₄ or PF₆) were applied as ionic solvents. The catalytic performance for cyclooctene epoxidation depends strongly on the catalyst solubility in the IL. Of the 12 catalyst/IL mixtures examined, the systems 1/[BMIM]PF₆ and 1/[BMPy]PF₆ exhibit the most favorable reaction rates allied with good recyclability. The 1/[BMIM]PF₆ system was further applied using different oxidants (aqueous TBHP, aqueous H₂O₂ and urea–hydrogen peroxide adduct) and olefins (norbornene, cyclohexene, styrene, α-pinene).     

The European Neurological Network database and sleep atlas

An international classification of sleep disorders has been established with definitions for 88 distinct sleep disorders in 1990, and the revised form was presented in 1997. The European Neurological Network (ENN) was set up in order to close the gap of knowledge between primary care physicians and sleep experts. The ENN database and sleep atlas were created within the framework of this network to support this goal. A collection of documented patient case stories with explanations of diagnoses and procedures, with images and video clips and with full night biosignal recordings, serves as an interactive teaching atlas for sleep disorders. This tutorial has been implemented on a set of four CD-ROMs. A subset of the multimedia sleep atlas and database was installed on a dedicated password protected server on the Internet to promote education in sleep medicine to all interested physicians. This article discusses the building of the database and atlas and also presents a case example     

Aging of Model Pressure Sensitive Adhesives Studied with Scanning Probe Microscopy

Changes in the surface morphology and surface friction of a tackified model pressure sensitive adhesive (PSA) with aging have been observed directly with atomic force microscopy. Changes over many months at room temperature as well as changes during brief exposure to two elevated temperatures (65 and 100°C) were characterized. Performance of the PSA, consisting of poly(ethylene propylene) with n-butyl ester of abietic acid as the tackifier, was studied qualitatively with nanoindentation.

Tackifier-enriched domains at the blends' surfaces grew and then coalesced with aging and the surface friction decreased as a result. Also, the polymer-enriched matrix stiffened with time. These two effects led to a stiffer surface, poorly suited to wetting an adherend. Domain coalescence was markedly accelerated upon brief exposure to a temperature ramp up to 100°C. At the highest temperatures studied, degradation of the polymeric matrix decreased its stiffness.     

Optimization of Radial Basis Function neural network employed for prediction of surface roughness in hard turning process using Taguchi’s orthogonal arrays

This work presents a study on the applicability of radial base function (RBF) neural networks for prediction of Roughness Average (R_a) in the turning process of SAE 52100 hardened steel, with the use of Taguchi’s orthogonal arrays as a tool to design parameters of the network. Experiments were conducted with training sets of different sizes to make possible to compare the performance of the best network obtained from each experiment. The following design factors were considered: (i) number of radial units, (ii) algorithm for selection of radial centers and (iii) algorithm for selection of the spread factor of the radial function. Artificial neural networks (ANN) models obtained proved capable to predict surface roughness in accurate, precise and affordable way. Results pointed significant factors for network design have significant influence on network performance for the task proposed. The work concludes that the design of experiments (DOE) methodology constitutes a better approach to the design of RBF networks for roughness prediction than the most common trial and error approach.     

Crack avoidance in steel piston rings through the optimization of process and gas nitriding parameters

This paper describes research into adequately estimating the main variables of a thermochemical gas nitriding process of stainless steel parts for engine components. The paper lays out an experimental strategy for the nitriding process that optimizes a set of variables that have a bearing on the occurrence of nitriding cracks. The results demonstrate that several factors and interactions are relevant in the occurrence of nitriding cracks. The proposed strategy was found to be effective at achieving continuous improvement and stricter control.     

Treatment of an ECF effluent by combined use of activated sludge and advanced oxidation process.

The combined biological and chemical treatments of the cellulose effluents have been studied aiming to promote a more significant degradation of their recalcitrant compounds and to reduce their toxicity, as compared with the isolated treatments. In this work the effluent from acid stages of the ECF bleaching of Eucalyptus urograndis pulp was treated by using separately activated sludge and UV radiation and its combination. The treatment efficiency was evaluated by colour, total phenol, COD, BOD, UV spectroscopy, molar weight distribution and toxicity. The untreated effluent presented 587 +/- 18 CU, 19.3 +/- 0.6 mg.L(-1) of total phenol, 2246 +/- 137 mgO2.L(-1) of COD and 904 +/- 48 mgO2.L(-1) of BOD. It did not show acute toxicity to Escherichia coli, but presented chronic toxicity to Selenastrum capricornutum (EC50 = 25%). The sludge treatment resulted in a colour increasing of 42% and decreasing of total phenol, COD and BOD of 33%, 64% and 92%, respectively. The UV radiation treatment for 120 min resulted in a decrease of colour, total phenol, BOD and COD of 70%, 43%, 62% and 43%, respectively. The combined treatment promoted an expressive decrease for colour and total phenol. The UV absorption indicated a degradation of the aromatic compounds. The biological treatment did not remove chronic toxicity and after UV radiation treatment, a 10 times improving toxicity was noticed.     

Structure of two fragments of the third cytoplasmic loop of the rat angiotensin II AT1A receptor. Implications with respect to receptor activation and G-protein selection and coupling

Managed care is an increasingly widespread way of delivering health care that combines medical care provider systems (doctors, nurses, clinics, hospitals) with the payor system (health insurance). This article gives a historical overview of managed health care, discusses managed HIV care, and managed care reform.     

Numerical simulation of atmospheric boundary layer flow over isolated and vegetated hills using RAMS

Atmospheric boundary layer flows over hills are important in the analysis of wind energy systems, dispersion of pollutants in the atmosphere and many meteorological and engineering applications. The objective of this work is to use the Regional Atmospheric Modeling System (RAMS), a numerical mesoscale model generally used for weather forecast and atmospheric case studies, to simulate the flow over isolated hills, covered with vegetation of uniform and non-uniform roughness length. The ability of the model to simulate this type of flows is tested by comparison with actual microscale data. The flow is assumed to be two-dimensional and quasi-steady, and the atmosphere is dry under statically neutral and non-neutral stability conditions. The numerical grid covers a large physical domain, with constant mesh spacing in the horizontal direction and a telescopic mesh in the vertical direction. All cases studied show that the domain size, the boundary conditions and the turbulence models play an important role in the simulations. The numerical results indicate that the Mellor and Yamada turbulence model performs better than the Smagorinsky model. When compared to the Askervein, Black Mountain, Cooper's Ridge field data and other numerical and analytical results from the literature, the RAMS results predict reasonably well the vertical profiles of the mean velocity and of the absolute and relative speedups.