Effects of block shape and inclination on the stability of melange bimrocks

Bulletin of Engineering Geology and the Environment - A wide range of heterogeneous geological units composed of strong rock blocks enclosed in a bonded matrix of fine texture exists worldwide....     

Liquid metal corrosion of 316L,Fe<Subscript>3</Subscript>Al,and FeCrSi in molten Zn-Al baths

Corrosion tests of 316L and two intermetallic compounds Fe₃Al and FeCrSi in industrial Galvanizing (Zn-0.18Al), GALFAN (Zn-5Al), GALVALUME (Zn-55Al), and Aluminizing (Al-8Si) baths and lab-scale static baths were conducted. In on-line tests in industrial hot-dip baths, 316L steel shows better corrosion resistance than Fe₃Al in Galvanizing, GALFAN, and GALVALUME baths. The corrosion resistance of 316L and Fe₃Al is similar in Aluminizing bath. In static tests, FeCrSi shows the best corrosion resistance in pure Zn, Zn-55Al, and Al-8Si baths. The corrosion resistance of 316L is better than that of Fe₃Al. In Zn-5Al bath, 316L shows no thickness loss after the test. For the same bath composition, the corrosion rates of the alloys in industrial baths are higher than those in static baths. Bath temperature and chemical composition play important roles in corrosion and intermetallic layer formation. Increasing bath temperature accelerates the corrosion process and changes the nature of intermetallic layers. A small amount of aluminum reduces the corrosion process by reducing the activity of Zn and forming inhibition layer. However, after aluminum content reaches the critical point, the dominant corrosion process changes from Zn-Fe reaction to Al-Fe reaction, and, consequently, the corrosion process accelerates by increasing aluminum content in the bath.     

Fast Separation of Capsaicinoids from Peppers by Reversed Phase Ultra-Performance Liquid Chromatography: Comparation with Traditional High-Performance Liquid Chromatography Methods

A new chromatographic method for the separation of major capsaicinoids in peppers has been developed. Nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin have been separated by reversed-phase ultra-performance liquid chromatography. A gradient method has been developed using two solvents: 0.1% acetic acid in water and 0.1% acetic acid in methanol. The developed method allows the full separation of capsaicinoids in less than 3 min, with high reproducibility (relative standard deviation < 4.3%) and repeatability (relative standard deviation < 3.6%). Robustness regarding the total amount of methanol in the sample was determined. Comparison with previous reversed-phase high-performance liquid chromatography methods using both monolithic and conventional columns was also studied. Finally, the method was applied in the determination of major capsaicinoids in 16 hot pepper samples produced in Spain.     

Removal of N‐methylpyrrolidone hydrogen‐bonded to polyaniline free‐standing films by protonation–deprotonation cycles or thermal heating

Free‐standing films of polyaniline (PANI), in an emeraldine base state, prepared by evaporation of polymer solutions in N‐methylpyrrolidone (NMP) retain solvent even under dynamic vacuum drying as indicated by transmission Fourier transform infrared (FTIR) spectroscopy, where a band at 1670 cm^?1 is clearly observed. Upon protonation–deprotonation cycles in aqueous media the weight of the dry base film decreases indicating gradual loss of NMP. Transmission FTIR spectra shows also the washing out of NMP with a clear decrease in intensity of the hydrogen‐bonded >C?O stretching band (1670 cm^?1) of NMP. During this process the bands between 3500 and 3200 cm^?1, assigned to >N? H stretching in the PANI backbone, change intensity suggesting that intermolecular hydrogen‐bonded >N? H, with carbonyl oxygen of NMP, is replaced by free >N? H. This is clear evidence of specific interaction of NMP with the emeraldine base. A similar loss of NMP is observed during heating but evidence of polymer degradation is also present. A mechanism is proposed to account for the loss of hydrogen‐bonding ability upon protonation which requires delocalization of the radical cations in the protonated films. © 2001 Society of Chemical Industry     

Clipping algorithms for solving the nearest point problem over reduced convex hulls

The nearest point problem (NPP), i.e., finding the closest points between two disjoint convex hulls, has two classical solutions, the Gilbert-Schlesinger-Kozinec (GSK) and Mitchell-Dem’yanov-Malozemov (MDM) algorithms. When the convex hulls do intersect, NPP has to be stated in terms of reduced convex hulls (RCHs), made up of convex pattern combinations whose coefficients are bound by a μ<1 value and that are disjoint for suitable μ. The GSK and MDM methods have recently been extended to solve NPP for RCHs using the particular structure of the extreme points of a RCH. While effective, their reliance on extreme points may make them computationally costly, particularly when applied in a kernel setting. In this work we propose an alternative clipped extension of classical MDM that results in a simpler algorithm with the same classification accuracy than that of the extensions already mentioned, but also with a much faster numerical convergence.     

Numerical Investigation of the Effect of Impeller Design Parameters on the Performance of a Multiphase Baffle‐Stirred Reactor

The turbulent gas‐liquid flow field in an industrial 100‐m³ stirred tank was calculated by using computational fluid dynamics based on the finite‐volume method. Turbulent effects were modeled with the shear stress transport model, and gas‐liquid bubbly flow was modeled with the Eulerian‐Eulerian approach using the Grace correlation for the drag force interphase momentum transfer. The relative motion between the rotating impeller and the stationary baffled tank was considered by using a multiple frames of reference algorithm. The effects of Rushton and pitched‐blade impeller design parameters such as blade geometry, location, and pumping direction on the mixing performance were investigated. It was found that a combination of Rushton turbines with up‐pumping pitched‐blade turbines provides the best mixing performance in terms of gas holdup and interfacial area density. The approach outlined in this work is useful for performance optimization of biotechnology reactors, as typically found in fermentation processes.     

The triple point of pure normal-deuterium

The triple point temperature of pure normal-deuterium was determined on IPTS-68 using a calorimetric technique in an adiabatic cryostat and samples of about 0.2 mol of deuterium, 99.86% pure, permanently sealed in small metal cells. The temperature value was found to be 18.729 ± 0.002 K. Two thirds of the quoted uncertainty was due to the differences in IPTS-68 calibrations from NBS, NPL and PRM); differences in a range of 4.2 mK were observed using five calibrated thermometers. Natural para-ortho conversion rate was observed to be 7 ± 2h^?1 at 18.7 K; the rate of conversion back to normal composition for the gas at 20 MPa and ambient temperature was 3 ± 1h¹. The enthalpy of melting was 199 ± 1 Jmol^?1.     

Allylsilanes and vinylsilanes from silylcupration of carbon-carbon multiple bonds: scope and synthetic applications

Silylcupration of multiple bonds (allenes, acetylenes, dienes, and styrenes) has become one of the most efficient procedures for the synthesis of vinyl- and allylsilanes. These substrates are useful building blocks in organic synthesis since they undergo a great variety of silicon-assisted transformations. The methodology reported has been widely used in the synthesis of different natural products, as well as in the construction of carbo- and heterocycles. In this Account, we wish to illustrate our contribution to this field, as well as to highlight the contributions of others.