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361.
Determination of trace level of selenium and mercury in photographic emulsions by atomic spectroscopy techniques 总被引:1,自引:0,他引:1
Trace level of selenium and mercury in photographic emulsion are used to improve photographic properties. The presence of silver halide in photographic emulsion does not allow the application of the most common analytical methods such as Hydride Generation Atomic Absorption Spectrometry (HG-AAS) and cold vapour Atomic Absorption Spectrometry (CV-AAS). Besides, silver removal was not quantitative, leading to a significant loss of the analytes and low reproducibility. The present work suggest the use of inductively coupled plasma Atomic Emission Spectrometry (ICP-AES) equipped with Ultrasonic Nebulizer (USN) for direct aqueous samples analysis at microgram l-1 level (d.l. 5.1 ppb for Hg and 6.1 ppb for Se). 相似文献
362.
Emanuele Pacifici 《Archiv der Mathematik》2005,84(1):1-10
Let G be a finite group, and V a finite-dimensional semisimple G-module over a finite field. Assume that V is endowed with a nonsingular bilinear form which is symmetric or symplectic, and which is invariant under the action of G. In this setting, we compute the number of anisotropic simple submodules of V.Received: 25 May 2004 相似文献
363.
Paolo?ButtàEmail author Emanuele?Caglioti Carlo?Marchioro 《Communications in Mathematical Physics》2004,249(2):353-382
We consider an infinite Hamiltonian system in one space dimension, given by a charged particle subjected to a constant electric field and interacting with an infinitely extended system of particles. We discuss conditions on the particle/medium interaction which are necessary for the charged particle to reach a finite limiting velocity. We assume that the background system is initially in an equilibrium Gibbs state and we prove that for bounded interactions the average velocity of the charged particle increases linearly in time. This statement holds for any positive intensity of the electric field, thus contradicting Ohms law.Work partially supported by the GNFM-INDAM and the Italian Ministry of the University. 相似文献
364.
365.
Fabrizio Cinquini Cristiana Di Valentin Emanuele Finazzi Livia Giordano Gianfranco Pacchioni 《Theoretical chemistry accounts》2007,117(5-6):827-845
Oxides surfaces and thin films are finding continuous new technological applications and represent an important class of systems in materials science. Today we assist to a considerable effort to characterize the surfaces and the interfaces of oxide materials at an atomistic level. The intense experimental activity in this field has stimulated a parallel computational activity based on high-quality first principle calculations. In this review we focus our attention on the properties of oxide surfaces, and we describe the main factors that contribute to determine their behaviour: (1) nature of the bonding and electronic structure of the oxide; (2) surface morphology and defectivity; (3) doping and functionalization; (4) redox properties; (5) nano-dimensionality (e.g. in ultra-thin films). We also show how each of these parameters can affect the properties of supported metal atoms and nano-particles. 相似文献
366.
The molecular species of phospholipids (PLs) and glycolipids (GLs) were simultaneously characterized in the pulp and almond of the avocado fruit (Persea americana Mill) of four varieties by means of high performance liquid chromatography-electrospray ionisation ion-trap tandem mass spectrometry. In the pulp, the predominant species of monoglycosyldiglycerides (MGD) were m/z 796.6 (oleic/linolenic and linoleic/linoleic acids) and m/z 800.4 (stearic/linoleic and oleic/oleic acids). One of the main diglycosyldiglycerides (DGD) both in the pulp and almond was m/z 958.5 (oleic/linolenic); however, the pulp was also rich of m/z 962.4 (oleic/oleic), whereas in the almond, m/z 934.5 (palmitic/linoleic and palmitoleic/oleic) and m/z 960.5 (oleic/linoleic and stearic/linolenic) were more abundant. In the almond, the main PL classes (phosphatidic acid (PA), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI)) contained always palmitic/linoleic acids. Alpha-linolenic acid was contained as MGD (linolenic/linolenic) and DGD (linolenic/linolenic), more present in the pulp than in the almond. The major molecular species of glycocerebrosides (GCer) in the pulp and almond carried hydroxy-palmitic acid (C(16h:0))/4,8-sphyngadienine (d(18:2)). 相似文献
367.
Mativetsky JM Liscio A Treossi E Orgiu E Zanelli A Samorì P Palermo V 《Journal of the American Chemical Society》2011,133(36):14320-14326
Here, we describe a simple approach to fabricate graphene-based field-effect-transistors (FETs), starting from aqueous solutions of graphene-oxide (GO), processed entirely under ambient conditions. The process relies on the site-selective reduction of GO sheets deposited in between or on the surface of micro/nanoelectrodes. The same electrodes are first used for voltage-induced electrochemical GO reduction, and then as the source and drain contacts of FETs, allowing for the straightforward production and characterization of ambipolar graphene devices. With the use of nanoelectrodes, we could reduce different selected areas belonging to one single sheet as well. 相似文献
368.
Pesce G Mandracchia B Orabona E Rusciano G De Stefano L Sasso A 《Lab on a chip》2011,11(23):4113-4116
In this work, we show a new technique to measure the direction and amplitude of the electric field generated by microelectrodes in a liquid environment, as often used in microfluidic devices. The method is based on the use of optical tweezers as a force transducer. A trapped, charged particle behaves as a probe. With this technique, it is possible to obtain a detailed map of the electric field, even for very complex electrode structures with a resolution below a micrometre and with a sensitivity as low as a few hundreds of V m(-1). 相似文献
369.
By using a generic coarse grained polypeptide model, we perform multicanonical molecular dynamics simulations for determining the equilibrium conformation state diagram of a single homopolypeptide chain as a function of the chain length and temperature. The state diagram highlights the thermal regimes of stability for various conformational patterns in polypeptides, including swollen, random and collapsed coils, globular structures, extended and bended α helices, and compact β bundles. Remarkably, at low temperatures we observe a sharp transition from extended α helix to compact β bundles as the chain length increases. This finding indicates that the chain length is one of the intrisic factors that can trigger α-β transformations in a broad class of polypeptides. 相似文献
370.
Scopelliti PE Bongiorno G Milani P 《Combinatorial chemistry & high throughput screening》2011,14(3):205-216
The aim of this review is to describe and to analyze the ingredients that are necessary in order to develop a robust and effective experimental approach for the high-throughput characterization of protein-nanostructured surface interaction. In the first part of this paper we review the nanostructured surface synthesis methods that are potentially able to create nanostructured inorganic surface libraries. In the second part, we address another fundamental aspect consisting in the availability of high-throughput proteins detection methods. We describe in details new emerging analytical tools compatible with nanostructured surfaces, analyzing different possible strategies, depending on the objective of the experiment and on the library format. 相似文献