Search results for " Phase"
showing 10 items of 1862 documents
Routine application using single quadrupole liquid chromatography-mass spectrometry to pesticides analysis in citrus fruits.
2005
Abstract A rapid and sensitive liquid chromatography–electrospray ionization–mass spectrometry method has been developed for the routine analysis of buprofezin, bupirimate, hexaflumuron, tebufenpyrad, fluvalinate and pyriproxyfen in citrus fruits. Extracts were obtained by matrix solid-phase dispersion (MSPD) using C 18 as dispersant and dichloromethane-methanol (80:20, v/v) as eluent. Matrix effects were tested for all matrices by addition of standard to sample blank extracts (samples containing no detectable residues). Mean recoveries obtained at fortification levels between 0.01 and 5 mg kg −1 were 57–97% with relative standard deviations (RSDs) from 5 to 19%. The limits of quantificatio…
Liquid chromatography–electrospray quadrupole ion-trap mass spectrometry of nine pesticides in fruits
2004
A liquid chromatographic method, with electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS), has been developed for determining acrinathrin, carbosulfan, cyproconazole, lambda-cyhalothrin, kresoxim methyl, pyrifenox, pyriproxyfen, propanil, and tebufenpyrad in fruits. The ions prominent in ESI spectra were [M + H]+ and [M + Na]+. In the mass analyzer, collision-induced dissociation fragmentation involved common pathways, for example, product ions of [M + H]+ resulted from the cleavage of the carbamic group or an oxygen bound. The utility of the method is demonstrated by the analysis of crude extracts obtained by matrix solid-phase dispersion (MSPD) using C18 as dispersant and dich…
Gas phase infrared multiple photon dissociation spectra of positively charged sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle-like aggregates
2011
The capability of infrared multiple photon dissociation (IRMPD) spectroscopy to gain structural information on surfactant-based supramolecular aggregates has been exploited to elucidate intermolecular interactions and local organization of positively charged sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) aggregates in the gas phase. A detailed analysis of the stretching modes of the AOTNa CO and SO(3)(-) head groups allows one to directly probe their interactions with sodium counterions and to gain insight in their organization within the aggregate. Similarities and differences of the IRMPD spectra as compared to the infrared absorption spectrum of micellized AOTNa in CCl(4) have been analy…
A noise analyzer for monitoring static electrification current
2005
Abstract This paper presents a static electrification current signal analyzer used for measuring and processing of the variable component of the changes in electrostatic charge that occur on a solid-body/liquid boundary interface. Due to high sensitivity and low uncertainty, the analyzer allows a precise evaluation of the phenomenon generated. The device operates in a spinning-disk system. The tests carried out indicate that it is possible to measure random components which depend, to a large extent, on hydrodynamic conditions and on the properties of the liquid phase. The device can be applied to the testing of transformer oils. It can be also used for measurements of other liquids having …
Order-disorder-and order-order-transitions in AB and ABC block copolymers: description by a simple model
1996
Based on the description of AB-block copolymers as micellar structures given by Semenov, the phase diagram of AB-diblock copolymers is calculated taking the homogeneously mixed system as a reference state. The predicted value (χN)c = 10.385 for a symmetric AB-diblock copolymer compares very well to the result of the original Random Phase Approximation theory (10.495). The simplicity of the model allows its extension to predict order-order transitions in ABC-triblock copolymers.
Small clusters with anisotropic antiferromagnetic exchange in a magnetic field
2004
We consider small symmetric clusters of magnetic atoms (spins) with anisotropic exchange interaction between the atoms in a magnetic field at zero temperature. The inclusion of the anisotropy leads to a wealth of different phases as a function of the applied magnetic field. These are not phases in the thermodynamic sense with critical properties but rather physical structures with different arrangements of the spins and hence different symmetries. We study the spatial symmetry of these phases, for the classical and quantum cases. Results are presented mainly for three frustrated systems, the triangle, the tetrahedron and the five-atom ring, which have many interesting features. In the class…
Wavelet Frames Generated by Spline Based p-Filter Banks
2014
This chapter presents a design scheme to generate tight and so-called semi-tight frames in the space of discrete-time periodic signals. The frames originate from oversampled perfect reconstruction periodic filter banks. The filter banks are derived from discrete-time and discrete periodic splines. Each filter bank comprises one linear phase low-pass filter (in most cases interpolating) and one high-pass filter, whose magnitude response mirrors that of a low-pass filter. In addition, these filter banks comprise a number of band-pass filters. In this chapter, frames generated by four-channel filter banks are briefly outlined (see Chap. 17 in [2] for details) and tight frames generated by six-…
EMG amplitude of the biceps femoris during jumping compared to landing movements.
2013
Abstract Hamstrings injury is a common occurrence in athletic performance. These injuries tend to occur during a deceleration or landing task suggesting the negative work may be a key component in hamstrings injury. The purpose of this study was to investigate the muscular activity (EMG) of the biceps femoris (BF) in different phases (concentric vs. eccentric) of a Counter Movement Jump (CMJ), Squat Jump (SJ) and the Braking Phase (BP) of a landing task. Twelve female volleyball players performed 5 CMJs, SJs and BPs while surface EMG was recorded using a MuscleLab (BoscoSystemTM, Norway). EMG values were normalized to an maximal voluntary contraction. A repeated measures analysis of varianc…
Lipid and phase specificity of α-toxin from S. aureus
2013
AbstractThe pore forming toxin Hla (α-toxin) from Staphylococcus aureus is an important pathogenic factor of the bacterium S. aureus and also a model system for the process of membrane-induced protein oligomerisation and pore formation. It has been shown that binding to lipid membranes at neutral or basic pH requires the presence of a phosphocholine-headgroup. Thus, sphingomyelin and phosphatidylcholine may serve as interaction partners in cellular membranes. Based on earlier studies it has been suggested that rafts of sphingomyelin are particularly efficient in toxin binding. In this study we compared the oligomerisation of Hla on liposomes of various lipid compositions in order to identif…
La mobilità volontaria nel Pubblico Impiego: margini di discrezionalità dell'Amministrazione di destinazione
2022
Il contributo, a partire da una recente pronuncia del Tribunale di Catanzaro, affronta la questione dei margini di discrezionalità della pubblica amministrazione reclutante nei procedimenti di mobilità individuale volontaria ex art. 30 d.lgs. n. 165/2001, con specifico riferimento alla fase di valutazione delle competenze professionali dei candidati. Ciò offre l’occasione per soffermarsi sulla natura dell’istituto, anche alla luce dei più recenti approdi legislativi in materia.