Nd5(AsO3)4Cl3: The First Oxo‐Arsenate(III)‐Chloride of the Lanthanides

Single crystals of Nd₅(AsO₃)₄Cl₃ (monoclinic, P2/n, Z = 2, a = 1026.0(1), b = 543.35(3), c = 1400.2(1) pm, β = 93.48(1)°) were obtained from the reaction of Nd₂O₃, As₂O₃ and NaCl in a sealed silica ampoule. In the crystal structure the Nd³⁺ ions are linked by AsO₃^3? groups into layers that alternate with layers of Cl^? ions. Two of the three crystallographically different Nd³⁺ ions are coordinated by eight oxygen atoms, the third one has four oxygen and four chlorine atoms as neighbours.     

Alkaline hydrolysis of ethiofencarb: Kinetic study and mechanism degradation

The present paper deals with the hydrolysis of ethiofencarb [2‐ethylthiomethyl(phenyl)‐N‐methylcarbamate] in alkaline solution. The reaction kinetics has been investigated using spectrophotometric and liquid chromatographic techniques. The rate constants were determined following a proposed first‐order kinetic model. The positive activation entropy Δ S^≠ = +100.07 J mol^?1 K^?1 and the absence of general basic catalysis indicated an E1cB hydrolytic mechanism, involving the formation of methyl isocyanate. This result was confirmed by the fact that ethiofencarb fits well into Brönsted and Hammett lines, obtained for a series of substituted N‐methylcarbamate whose decomposition in aqueous media was established to follow an E1cB mechanism. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 118–124, 2013     

Fluid-fluid interaction during miscible and immiscible displacement under ultrasonic waves

This paper aims at identifying and analyzing the influence of high-frequency, high-intensity ultrasonic radiation at the interface between immiscible (different types of oils and aqueous solutions) and miscible (different types of oil and solvent) fluids. An extensive set of Hele-Shaw type experiments were performed for several viscosity ratios, and interfacial tension. Fractal analysis techniques were applied to quantify the degree of fingering and branching. This provided a rough assessment of the degree of perturbation generated at the interface when the capillary forces along with the viscous forces are effective. Miscible Hele-Shaw experiments were also presented to isolate the effect of viscous forces. We found that ultrasound acts to stabilize the interfacial front, and that such effect is most pronounced at low viscosity ratios. An erratum to this article is available at .     

A study of the level properties of 57Co from the (τ, d) reaction on 56Fe

The ⁵⁶Fe(τ, d)⁵⁷Co reaction has been studied at E_τ = 18 MeV using the Tandem Van de Graaff accelerator and the multichannel magnetic spectrograph of the Nuclear Physics Laboratory, Oxford, Angular distributions have been measured for most of the levels up to E_x ≈ 7.8 MeV and are analysed in terms of the DWBA theory of direct reactions. The l_p values and the transition strengths compared with available theories.     

Microwave‐Assisted Synthesis of Quinoline Derivatives from Isatin

Microwave irradiation has been used for a rapid and efficient synthesis of quinoline‐4‐carboxylic acids 5a–g and 1,2,3,4‐tetrahydroacridine‐9‐carboxylic acid (6) from the reaction of isatins 1–3 with acyclic and cyclic ketones in basic medium. 2‐Hydroxyquinoline‐4‐carboxylic acid (11) was also obtained by irradiating a mixture of isatin 1 and malonic acid in AcOH. The esters of 5f and 11 and their respective hydrazides 8 and 13 were also prepared under MWI.     

Dynamic mechanical properties of suspensions of micellar casein particles

Small micellar casein particles, so-called submicelles, were obtained by removing colloidal calcium phosphate from native casein by adding sodium polyphosphate. Aqueous submicelle suspensions were characterized using light scattering and rheology as a function of concentration and temperature. The casein submicelles behave like soft spheres that jam at a critical concentration (C(c)) of about 100 g L(-1). The viscosity does not diverge at C(c), but increases sharply, similarly to that of multiarm star polymers. C(c) increases weakly with increasing temperature, which leads to a strong decrease of the viscosity close to and above C(c). Concentrated submicelle suspensions show strong shear-thinning above a critical shear rate and the shear stress becomes independent of the shear rate. The critical shear rates at different temperatures and concentrations are inversely proportional to the zero-shear viscosity. At much higher shear rates, the shear stress fluctuates strongly in time indicating inhomogeneous flow. The frequency dependence of casein submicelle suspensions is characterized by elastic behavior at high frequencies (concentrations) and viscous behavior at low frequencies (concentrations).     

Independent component analysis as a pretreatment method for parallel factor analysis to eliminate artefacts from multiway data

Parallel factor analysis (PARAFAC) has successfully been used in many applications for the analysis of excitation-emission fluorescence data. However, some measurement “artefacts”, such as Rayleigh or Raman scattering, can pose a problem for the extraction of the PARAFAC components and their interpretation. Replacing the spectral zones corresponding to these signals by missing values in the data is not necessarily a method of choice in the cases where informative signals lie in the same wavelength regions. In this article, independent component analysis (ICA) is used on the unfolded cubic array, and the independent components related to the Rayleigh and Raman scattering are identified and removed prior to the reconstruction of the excitation-emission fluorescence data cube. PARAFAC is then applied on these data reconstructed after selective artefact removal, and satisfactory models can be obtained. This procedure, although particularly useful for 3D fluorescence data, may be applied to other types of data as well.     

General phase transition models for vehicular traffic with point constraints on the flow

In this paper, we present a general phase transition model that describes the evolution of vehicular traffic along a one‐lane road. Two different phases are taken into account, according to whether the traffic is low or heavy. The model is given by a scalar conservation law in the free‐flow phase and by a system of 2 conservation laws in the congested phase. The free‐flow phase is described by a one‐dimensional fundamental diagram corresponding to a Newell‐Daganzo type flux. The congestion phase is described by a two‐dimensional fundamental diagram obtained by perturbing a general fundamental flux. In particular, we study the resulting Riemann problems in the case a local point constraint on the flow of the solutions is enforced.     

Ab-initio calculations of the optical and magnetic properties of erbium silicide ErSi2

We present a computational method for the ab-initio study of the optical and magnetic properties using the augmented plane wave plus local orbitals (APW+lo) method. The calculations are presented within the local density (LDA) approximation. Erbium silicide (ErSi₂) is representative of the whole trivalent heavy-rare-earth disilicides family, and its study will provide information valid for all of them. Thus, the study of its optical and magnetic properties is very important, especially for the calculation of magneto-optical quantities. In this paper the optical and magnetic properties are well described. Up to now no theoretical study on optical and magnetic properties of ErSi₂ is available in the literature. We report theoretical calculations of the reel and imaginary parts of the dielectric function (DF), the refractive index and the extinction coefficient, the spectra of the reflectivity, the absorption coefficient, the energy-loss function (ELF), and the magnetic moments.     

Effect of Shear Flow on Nanoparticles Migration near Liquid Interfaces

The effect of shear flow on spherical nanoparticles (NPs) migration near a liquid–liquid interface is studied by numerical simulation. We have implemented a compact model through which we use the diffuse interface method for modeling the two fluids and the molecular dynamics method for the simulation of the motion of NPs. Two different cases regarding the state of the two fluids when introducing the NPs are investigated. First, we introduce the NPs randomly into the medium of the two immiscible liquids that are already separated, and the interface is formed between them. For this case, it is shown that before applying any shear flow, 30% of NPs are driven to the interface under the effect of the drag force resulting from the composition gradient between the two fluids at the interface. However, this percentage is increased to reach 66% under the effect of shear defined by a Péclet number Pe = 0.316. In this study, different shear rates are investigated in addition to different shearing times, and we show that both factors have a crucial effect regarding the migration of the NPs toward the interfacial region. In particular, a small shear rate applied for a long time will have approximately the same effect as a greater shear rate applied for a shorter time. In the second studied case, we introduce the NPs into the mixture of two fluids that are already mixed and before phase separation so that the NPs are introduced into the homogenous medium of the two fluids. For this case, we show that in the absence of shear, almost all NPs migrate to the interface during phase separation, whereas shearing has a negative result, mainly because it affects the phase separation.