Search results for "medium"
showing 10 items of 3746 documents
Capillary electrophoresis–inductively coupled plasma-mass spectrometry hyphenation for the determination at the nanogram scale of metal affinities an…
2012
Abstract A screening strategy based on hyphenated capillary electrophoresis and inductively coupled plasma mass spectrometry (CE–ICP-MS) was developed to classify phosphorylated ligands according to their europium(III) binding affinity in a hydro-organic medium (sodium formate, pH 3.7, H2O/MeOH 90:10, v/v). Taking advantage of the high sensibility of ICP-MS for detecting phosphorus, this method enabled to assess the affinity of a variety of phosphorylated compounds, including phosphine oxides, thiophosphines, phosphonates, and phosphinates, in less than 1 h and using less than 5 ng of substance. By varying the total europium concentration, complexation constants could be determined accordin…
Validez de la información financiera en los procesos de insolvencia. Un estudio de la pequeña empresa española
2013
ResumenEn este trabajo nos proponemos un doble objetivo. Por un lado planteamos la posibilidad de que la presente crisis haya afectado de forma desigual a la motivación por la que las empresas fracasan, y por otra parte, como segundo objetivo, pretendemos contrastar la validez de ciertos modelos de predicción en un contexto de fuerte variación provocado por la crisis económica actual.Para ello, inicialmente someteremos la información de 2 muestras de datos financieros de pequeñas empresas a diversas pruebas estadísticas que pongan de manifiesto la variación de la información contable en 2 escenarios: uno de inexistencia de crisis y otro ante la situación de crisis financiera actual. Después…
Of Thiols and Disulfides: Methods for Chemoselective Formation of Asymmetric Disulfides in Synthetic Peptides and Polymers.
2018
In protein or peptide chemistry, thiols are frequently chosen as a chemical entity for chemoselective modification reactions. Although it is a well-established methodology to address cysteines and homocysteines in aqueous media to form S-C bonds, possibilities for the chemoselective formation of asymmetric disulfides have been less approached. Focusing on bioreversibility in conjugation chemistry, the formation of disulfide bonds is highly desirable for the attachment of thiol-containing bioactive agents to proteins or in cross-linking reactions, because disulfide bonds can combine stability in blood with degradability inside cells. In this Concept article, recent approaches in the field of…
Electrical resistivity of simple metal amorphous alloys at moderately low temperatures
2003
Abstract An approach is developed that allows to explain the unusual dependence of the electrical resistivity ρ(T) of amorphous alloys on temperature T. Interactions between the free electrons and the longitudinal acoustic excitations in the small-wavelength region (“the roton region”) are shown to cause such a behaviour of ρ(T) at moderately low temperatures. The features of the electron–phonon interactions in an amorphous alloy as compared to the crystal state case are discussed. The theory is illustrated by numerical calculations of the electrical resistivity ρ(T) for Mg–Zn and Cu–Sn amorphous alloys at the different alloy concentrations in the 0 K temperature range. Qualitative agreemen…
A novel One Domain Approach for free fluid-porous medium transport simulation. Preliminary results
2022
We present a new numerical solver for free-fluid flowing over and inside a porous medium. It is based over a macroscopic approach and one fictitious medium is assumed inside the domain, according to the One Domain Approach. Preliminary results are shown and compared with the ones provided by the well-known DuMux solver which applies a two Domain Approach.
Determination of dynamic properties of flax fibres reinforced laminate using vibration measurements
2017
International audience; Experimental and numerical methods to identify the linear viscoelastic properties of flax fibre reinforced polymer (FFRP) composite are presented in this study. The method relies on the evolution of storage modulus and loss factor as observed through the frequency response. Free-free symmetrically guided beams were excited in the dynamic range of 10 Hz to 4 kHz with a swept sine excitation focused around their first modes. A fractional derivative Zener model has been identified to predict the complex moduli. A modified ply constitutive law has been then implemented in a classical laminates theory calculation (CLT) routine. Overall, the Zener model fitted the experime…
A technical note on an experimental device to measure friction coefficient in sheet metal forming
2006
Abstract In the paper the authors present the results of several experimental tests aimed to determine the Coulomb friction coefficient in sheet metal forming operations at the varying of the sheet metal material and for different operative conditions. In particular a few pressure and lubricating conditions have been investigated. In order to develop such experiments a dedicated fixture was designed and set-up starting from the one proposed by Wilson.
Macrobotanical evidence (wood charcoal and seeds) from the Middle Palaeolithic site of El Salt, Eastern Iberia: Palaeoenvironmental data and plant re…
2018
Despite the current growing number of studies that focus on macrobotanical remains from Middle Palaeolithiccontexts, plant use among hunter-gatherer societies remains unknown in many regions of Europe. Large-scaleflotation of archaeological sediments has made it possible to recover a large amount of plant remains (fruits,seeds and wood) from units VIII, IX, Xa and Xb at El Salt, Eastern Iberia (49.2–52.3 ka BP). The combination ofanthracological and carpological analyses has provided a more accurate picture of the Middle Palaeolithiclandscape in the Serpis valley, as well as significant information about other possible uses of plants, not only asfuel, but for woodworking or food, for instan…
Comparison between aluminum alloys behavior in incremental sheet metal forming process of frustum pyramid shaped parts
2021
Abstract Single point incremental forming is a new emerging technology, used mainly for prototype development or small series production, with good prospects in industrial implementation. However, the parts manufactured through this process often presents low accuracy, thus the industrial implementation is yet limited. Incremental forming process can be done with the help of different technological equipment, such as industrial robots and numerically controlled machines. Since the process is still in development phase, it is a good practice to use finite element analysis software packages in order to reduce time and costs to produce accurate parts. The aim of this paper is to investigate th…
Selective Synthesis of Hollow and Filled Fullerene-like (IF) WS2 Nanoparticles via Metal–Organic Chemical Vapor Deposition
2007
The synthesis of WS2 onion-like nanoparticles by means of a high-temperature metal–organic chemical vapor deposition (MOCVD) process starting from W(CO)6 and elemental sulfur is reported. The react...