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521.
Ivana uri
kovi Rmy Claverie Patrice Bourson Mario Marchetti Jean‐Marie Chassot Marc D. Fontana 《Journal of Raman spectroscopy : JRS》2011,42(6):1408-1412
Raman spectroscopy was used to study the liquid–solid water phase transition. Special attention was devoted to the OH stretching band of the Raman spectrum, which shows monotonous changes in the temperature range between 10 and − 15 °C. The interpretation of this spectral change, as well as a careful analysis of its integrated scattered intensity, led to a spectral marker that allows the determination of the water phase (liquid or solid), and the efficient identification of the liquid–solid phase transition itself. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
522.
Andréia de Morais Gustavo Silveira Paulo César Mendes Villis Camila Marchetti Maroneze Yoshitaka Gushikem Fábio Luiz Pissetti Alzira Maria Serpa Lucho 《Journal of Solid State Electrochemistry》2012,16(9):2957-2966
A simple preparation methodology able to stabilize gold nanoparticles and to obtain an electrode which detects ascorbic acid, uric acid, and dopamine by different techniques is presented. A 3-mercaptopropyl-functionalized silica network was synthesized using the sol–gel method. Gold nanoparticles (nAu) were immobilized on the material at synthesis by adding a sol of these previously prepared particles to the reaction mixture. The electrochemical behavior of the SiO2/MPTS/Au carbon paste electrode was studied using cyclic voltammetry in the presence of a hexacyanoferrate probe molecule. The presence of nAu in the functionalized silica network changes the electrochemical characteristics of the material, favoring the electron transfer process of this complex ion. The SiO2/MPTS/Au electrode was proven to be an efficient tool in the simultaneous determination of ascorbic acid (H2AA), dopamine (DA), and uric acid (UA) using square wave voltammetry techniques. With the nAu on the electrode, an increase in the peak current related to the redox process of the H2AA, DA, and UA was observed. The separations of the anodic peak potentials between DA/H2AA and UA/H2AA were 310 and 442?mV, respectively. The results obtained show that the SiO2/MPTS/Au electrode can be used in the simultaneous determination of H2AA, DA, and UA. 相似文献
523.
Dell'Amico DB Labella L Marchetti F Samaritani S 《Dalton transactions (Cambridge, England : 2003)》2012,41(4):1389-1396
The syntheses of the complexes [PtCl(2)(NCR)L] [R = Me, Et; L = PPh(3); R = Et, L = Py, CO] and [PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] are described starting from the easily available [PtCl(2)(NCR)(2)]. The stability of the products under different experimental conditions is discussed as well as their use as precursors to dinuclear complexes [Pt(μ-Cl)ClL](2). The crystal and molecular structures of cis-[PtCl(2)(NCEt)(PPh(3))], [SP-4-2]-[PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] and trans-[Pt(μ-Cl){(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}](2) are reported. 相似文献
524.
Ellen Denise P. Almeida Adjane A. Costa Mairim R. Serafini Fábia C. Rossetti Juliana M. Marchetti Victor Hugo V. Sarmento Rogéria de S. Nunes Mário Ernesto G. Valerio Adriano A.S. Araújo Ana Amélia M. Lira 《Journal of Thermal Analysis and Calorimetry》2012,108(1):191-196
Solid lipid nanoparticles (SLN) without drug and SLN loaded with chloroaluminum phthalocyanine (AlClPc) were prepared by solvent
diffusion method in aqueous system and characterized by thermal analyses and X-ray diffraction (XRD) in this study. Determination
of particle size, zeta potential (ZP), and encapsulation efficiency were also evaluated. SLN containing AlClPc of nanometer
size with high encapsulation efficiency and ZP were obtained. The results indicated that the size of SLN loaded with AlClPc
is larger than that of the inert particle, but ZP is not changed significantly with incorporation of the drug. In differential
scanning calorimetry (DSC) curves, it was observed that the melting point of stearic acid (SA) isolated and in SLN occurred
at 55 and 64 °C, respectively, suggesting the presence of different polymorphs. DSC also shows that the crystallinity state
of SLN was much less than that of SA isolated. The incorporation of drug in SLN may have been favored by this lower crystallinity
degree of the samples. XRD techniques corroborated with the thermal analytic techniques, suggesting the polymorphic modifications
of stearic acid. 相似文献
525.
Resampling methods are often invoked in risk modelling when the stability of estimators of model parameters has to be assessed. The accuracy of variance estimates is crucial since the operational
risk management affects strategies, decisions and policies. However, auxiliary variables and the complexity of the sampling
design are seldom taken into proper account in variance estimation. In this paper bootstrap algorithms for finite population
sampling are proposed in presence of an auxiliary variable and of complex samples. Results from a simulation study exploring
the empirical performance of some bootstrap algorithms are presented.
相似文献
526.
Alberto Cavicchioli Yuri V. Muranov Fulvia Spaggiari 《Monatshefte für Mathematik》2009,158(4):367-391
In 1987 Kharshiladze introduced the concept of type for an element in a Wall group, and proved that the elements of first and second type cannot be realized by normal maps of closed manifolds. This approach is sufficiently easy for computing the assembly maps and sometimes very effective. Here we give a geometrical interpretation of this approach by using the Browder–Quinn surgery obstruction groups for filtered manifolds. To understand the obtained relations we give algebraic definitions of the element types which are based on the algebraic surgery theory of Ranicki. Our approach describes a level of indeterminate for the algebraic passing to surgery on a codimension k submanifold of a given Browder–Livesay filtration. Then we study the realization of splitting obstructions by simple homotopy equivalences of closed manifolds, and compute the assembly maps for some classes of groups. 相似文献
527.
Weighted event graphs (in short WEG) are widely used to model industrial problems and embedded systems. In an optimization context, fast algorithms checking the liveness of a marked WEG must be developed. The purpose of this paper is to develop a sufficient condition of liveness of a WEG. We first show that any unitary WEG can be transformed into a graph in which the values of the arcs adjacent to any transition depend on the transition. Then, a simple sufficient condition of liveness can be expressed on this new graph and polynomially computed. This condition is shown to be necessary for a circuit with two transitions. 相似文献
528.
A bisphenol-A diglycidyl ether resin, cured with isophorone-diamine at 60°C, was modified by means of preformed core-shell acrylic rubber particles. Blends with rubber contents up to 30 phr by wt were tested. The fracture toughness depended linearly on the amount of rubber and significant improvement was found. No deterioration of temperature resistance was also observed. The viscosity of resin/modifier mixtures was controlled by means of antifoaming agents. A comparison with liquid acrylonitrile-butadiene copolymers showed that core-shell particles are efficacious tougheners. The effect of a bimodal particle size distribution was considered. In the size range investigated (0.2+5μm) no synergic effect was observed. 相似文献
529.
Barbara Bulleri Massimo Genoni Giuseppe Gallone Augusto Marchetti 《Macromolecular Symposia》2004,218(1):363-371
The replacement of metals with plastics in piping systems is a well established practice in a vast range of public and industrial applications. However, difficulties still exist, mainly related to the limited chemical resistance of the polymers commonly used in pipe manufacturing to some conveyed fluids. This prevents using plastic pipes in important applications such as the transport of liquid hydrocarbons, particularly in oil fields. The use of chemically resistant polymers, such as fluorinated polyolefins, is precluded by high cost and poor mechanical properties. Co-extrusion of multi-layer pipes carrying an internal chemically resistant liner can be a viable alternative capable to extend the use of plastic pipes to refining and chemical industries. An experimental PE/PA multi-layer pipe has been developed whose resistance to diffusion and mechanical properties have been tested. Tests in real oil fields confirm the good performance of the new pipes. 相似文献
530.
Tolga N. V. Karsili Barbara Marchetti Marsha I. Lester Michael N. R. Ashfold 《Photochemistry and photobiology》2023,99(1):4-18
Interest in Criegee intermediates (CIs), often termed carbonyl oxides, and their role in tropospheric chemistry has grown massively since the demonstration of laboratory-based routes to their formation and characterization in the gas phase. This article reviews current knowledge regarding the electronic spectroscopy of atmospherically relevant CIs like CH2OO, CH3CHOO, (CH3)2COO and larger CIs like methyl vinyl ketone oxide and methacrolein oxide that are formed in the ozonolysis of isoprene, and of selected conjugated carbene-derived CIs of interest in the synthetic chemistry community. Of the aforementioned atmospherically relevant CIs, all except CH2OO and (CH3)2COO exist in different conformers which, under tropospheric conditions, can display strikingly different thermal loss rates via unimolecular and bimolecular processes. Calculated photolysis rates based on their absorption properties suggest that solar photolysis will rarely be a significant contributor to the total loss rate for any CI under tropospheric conditions. Nonetheless, there is ever-growing interest in the absorption cross sections and primary photochemistry of CIs following excitation to the strongly absorbing 1ππ* state, and how this varies with CI, with conformer and with excitation wavelength. The later part of this review surveys the photochemical data reported to date, including a range of studies that demonstrate prompt photo-induced fission of the terminal O–O bond, and speculates about possible alternate decay processes that could occur following non-adiabatic coupling to, and dissociation from, highly internally excited levels of the electronic ground state of a CI. 相似文献