Breath-held MR Cholangiopancreatography (MRCP) using a 3D Dixon fat–water separated balanced steady state free precession sequence

A novel 3D breath-held Dixon fat–water separated balanced steady state free precession (b-SSFP) sequence for MR cholangiopancreatography (MRCP) is described and its potential clinical utility assessed in a series of patients. The main motivation is to develop a robust breath-held alternative to the respiratory gated 3D Fast Spin Echo (FSE) sequence, the current clinical sequence of choice for MRCP. Respiratory gated acquisitions are susceptible to motion artifacts and blurring in patients with significant diaphragmatic drift, erratic respiratory rhythms or sleep apnea. A two point Dixon fat–water separation scheme was developed which eliminates signal loss arising from B₀ inhomogeneity effects and minimizes artifacts from perturbation of the b-SSFP steady state. Preliminary results from qualitative analysis of 49 patients demonstrate robust performance of the 3D Dixon b-SSFP sequence with diagnostic image quality acquired in a 20–24 s breath-hold.     

Euclidean realizations of Mauldin–Williams graphs

“Graph-directed” fractals are collections of metric spaces, each of which can be expressed as a union of several scaled copies of spaces from the collection. They give rise to weighted, directed graphs where the term comes from. We show in this note that any (finite) weighted, directed graph (with weights between 0 and 1) can be realized in a Euclidean space in the sense that, starting from the graph one can define a system of similitudes (with the similarity ratios being the given weights) on an appropriate Euclidean space. The point is that these maps satisfy a certain property (called the open set condition) so that the theory of Mauldin–Williams can be applied to compute the dimension of the emerging fractals. Additionally, we give a novel example of a system of graph-directed fractals.     

Dynamic phase transitions in a cylindrical Ising nanowire under a time-dependent oscillating magnetic field

The dynamic phase transitions in a cylindrical Ising nanowire system under a time-dependent oscillating external magnetic field for both ferromagnetic and antiferromagnetic interactions are investigated within the effective-field theory with correlations and the Glauber-type stochastic dynamics approach. The effective-field dynamic equations for the average longitudinal magnetizations on the surface shell and core are derived by employing the Glauber transition rates. Temperature dependence of the dynamic magnetizations, the dynamic total magnetization, the hysteresis loop areas and the dynamic correlations are investigated in order to characterize the nature (first- or second-order) of the dynamic transitions as well as the dynamic phase transition temperatures and the compensation behaviors. The system strongly affected by the surface situations. Some characteristic phenomena are found depending on the ratio of the physical parameters in the surface shell and the core. According to the values of Hamiltonian parameters, five different types of compensation behaviors in the Néel classification nomenclature exist in the system. The system also exhibits a reentrant behavior.     

A 3D balanced-SSFP Dixon technique with group-encoded k-space segmentation for breath-held non-contrast-enhanced MR angiography

A three-dimensional balanced steady-state free precession (b-SSFP)-Dixon technique with a novel group-encoded k-space segmentation scheme called GUINNESS (Group-encoded Ungated Inversion Nulling for Non-contrast Enhancement in the Steady State) was developed. GUINNESS was evaluated for breath-held non-contrast-enhanced MR angiography of the renal arteries on 18 subjects (6 healthy volunteers, 12 patients) at 3.0 T. The method provided high signal-to-noise and contrast renal angiograms with homogeneous fat and background suppression in short breath-holds on the order of 20 s with high spatial resolution and coverage. GUINNESS has potential as a short breath-hold alternative to conventional respiratory-gated methods, which are often suboptimal in pediatric subjects and patients with significant diaphragmatic drift/sleep apnea.     

The synthesis and characterization of some new vic-dioximes and their transition metal complexes

In this study, three new vic-dioximes, [L¹H₂], N-(5-chloro-2-methoxyphenyl)amino-1-acetyl-1-yclohexenylglyoxime, [L²H₂],N-(3-chloro-4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylgly-oxime and [L³H₂], N-(3-chloro-2-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II) and Co(II) salts. The structures of these new compounds (ligands and complexes) were characterized with FT-IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrophotometer measurements, thermal methods (TGA), ¹H NMR and ¹³C NMR spectral data and elemental analyses.     

White light luminescence from annealed thin ZnO deposited porous silicon

In this study, photoluminescence (PL) properties of annealed ZnO thin films deposited onto a porous silicon (PS) surface by rf-sputtering were investigated. A huge blue shift of luminescence from the ZnO deposited onto the PS surface and a broadband luminescence (white luminescence) across most of the visible spectrum were obtained after the heat treatment at 950 °C in air. The results of Fourier Transform Infrared Spectroscopy (FTIR) analysis suggested that the porous silicon surface was oxidized after ZnO deposition and the broadband luminescence was due to the conversion of Si-H bonds to Si-O-Si bonds on the PS surface. The underlying mechanisms of the broadband PL were discussed by using oxygen-bonding model for the PS and native defects model for ZnO. The experimental results suggested that the heat treatment provides a relatively easy way to achieve white luminescence from thin ZnO deposited porous silicon.     

Effective field study of the magnetism and superconductivity in idealised Ising-type X@Y60 endohedral fullerene system

In this study, effective-field calculations within Ising model framework have been utilised to investigate theoretically the effect of temperature and interaction parameters on the magnetic and hysteretic processes in an idealised system used to represent endohedral fullerene (EF) with a dopant magnetic atom confined within a spherical cage. The thermal behaviour of the partial (centre and surface) and the total magnetizations are studied to determine the character of phase transition (continuous and discontinuous) and to elaborate the phase diagram in interaction parameters plane. The total and partial hysteresis curves with susceptibility peaks and coercive fields are also given and focused on the influence of the temperature and interaction parameters. According to values of Hamiltonian parameters, the system exhibits the first- and second-order phase transitions and three types of compensation behaviour, namely Q-, R-, and S-types. In the phase diagram of the system, when the centre–surface (C–S) interaction increases or decreases, the phase transition temperature increases symmetrically. Finally, from the hysteresis curves of the system, we observed that type II superconducting-like behaviour can appear by the presence of dopant centre magnetic atom.     

Multicritical dynamical phase diagrams of the kinetic Blume–Emery–Griffiths model with repulsive biquadratic coupling in an oscillating field

We study, within a mean-field approach, the stationary states of the kinetic Blume–Emery–Griffiths model with repulsive biquadratic coupling under the presence of a time-varying (sinusoidal) magnetic field. We employ the Glauber-type stochastic dynamics to construct set of dynamic equations of motion. The behavior of the time dependence of the order parameters and the behavior of the average order parameters in a period, which is also called the dynamic order parameters, as functions of the reduced temperature are investigated. The dynamic phase transition points are calculated and phase diagrams are presented in the reduced magnetic field amplitude and reduced temperature plane. The dynamical transition from one regime to the other can be of first- or second order depending on the region in the phase diagram. According to the values of the crystal field interaction or single-ion anisotropy constant and biquadratic exchange constant, we find 20 fundamental types of phase diagrams which exhibit many dynamic critical points, such as tricritical points, zero-temperature critical points, double critical end points, critical end point, triple point and multicritical point. Moreover, besides a disordered and ordered phases, seven coexistence phase regions exist in the system.     

Erratum to: Simultaneous High-Performance Thin-Layer Chromatographic Determination of Indole Acetic Acid,Indole Butyric Acid,and Absisic Acid in in vitro Seedling of Watermelon Exposed to Heavy Metals

JPC – Journal of Planar Chromatography – Modern TLC - Simultaneous High-Performance Thin-Layer Chromatographic Determination of Indole Acetic Acid, Indole Butyric Acid, and Absisic Acid...