Equations of Electromagnetic Self-Consistency in a Plasma

The set of equations governing a system consisting of an electromagnetic field plus charges in it is obtainedby varying the appropriate action. It is not assumed that the currents are given, which in fact leads to the Maxwellequations governing the fields. Nor is it assumed that the fields are given, which in fact would lead to the determinationof the motions of the charges (the currents) through the Lorentz force. On the contrary, currents and fields are left freeto interplay, and they can be found simultaneously from the equations obtained.     

The Role of Discrete Capillary Rings in Mass Transfer From the Surface of a Drying Capillary Porous Medium

Transport in Porous Media - The mass exchange between the surface of a model capillary porous medium and the adjacent gas-side boundary layer is studied in the limiting condition of isothermal,...     

Electronic and geometric structure analysis of neutral and anionic alkali metal complexes of the CX series (X = O,S, Se,Te, Po): The case of M(CX) n = 1–4 (M = Li,Na) and their dimers

Bonding mechanisms, potential energy curves, accurate structures, energetics, and electron affinities are obtained for all M(CX)_1–3 species with M = Li, Na, and X = O, S, Se, Te, and Po, at the coupled-cluster level with triple-ζ quality basis sets. We discuss and rationalize the trends within different molecular groups. For example, we found larger binding energies for M = Li, for CX = CPo, and for the tri-coordinated (n = 3) complexes. All three facts are explained by the fact that the global minimum of the titled complexes originate from the first excited ²P (2p¹ for Li or 3p¹ for Na) state of the metal, with each ligand forming a dative bond with the metal. All of the complexes, except Na(CO)₃, have stable anions, and their electron affinity increases as MCX < M(CX)₃ < M(CX)₂. This sequence is attributed to the binding modes of these complexes. The Li(CO)₃ and Li(CS)₃ complexes are able to accommodate a fourth ligand, which is attached to the system electrostatically. Finally, two Li(CO)₃ molecules can bind together covalently to make the ethane analog. The staggered conformer was found lower in energy and unlike ethane the CO ligands bend toward the neighboring Li(CO)₃ moiety. © 2019 Wiley Periodicals, Inc.     

Chemometrically Assisted Optimization of Pregabalin Fluorescent Derivatization Reaction with a Novel Xanthone Analogue and Validation of the Method for the Determination of Pregabalin in Bulk via a Plate Reader

Quantitation of chromophore-free analytes is always a challenge. To this purpose, derivatization of the analyte constitutes a common strategy, leading to a product with a strong signal. In the current study, a novel xanthone analogue was utilized for the first time for the derivatization of pregabalin, a model analyte with a primary amine moiety that lacks a chromophore. The fact that only the xanthene-based derivative, formed after the derivatization reaction fluoresces, enables avoiding its chromatographic separation from the reagent and thus reducing the analysis time of a series of samples in 1–2 min via a plate reader. The reaction conditions were optimized via a central composite design (CCD), with fluorescence signal as the measure of the yield. The following factors that affect the derivatization reaction were chosen: (a) temperature, (b) reaction time, and (c) triethylamine solution volume used to drive the reaction to completion. After the identification of the optimal conditions, the method was validated according to ICH guidelines, using a fluorescence plate reader for signal measurement (λ_ex = 540, λ_em = 615 nm). Finally, the newly developed high-throughput method was applied to the determination of drug content in pregabalin bulk.     

The gem-Diol Form of (py)2CO as a Ligand in Cobalt(II) Carboxylate Clusters: A Cubane Complex and a Novel Nonanuclear Species with a Vertex-Sharing Double Square Pyramidal Structure

A vertex-sharing double square pyramid of cobalt(II ) ions (see picture) is present in the nonanuclear complex 1 , obtained by treating cobalt acetate with 0.5 equivalents of (py₂)CO. The corresponding 1:1 reaction gave 2 , which has a central core with a cubane structure. py=pyridine.     

MRI of blood volume with MS 325 in experimental choroidal melanoma

Functional magnetic resonance imaging (MRI) allows quantitative blood volume imaging in vivo at high tissue resolution. The purpose is to apply this technique for untreated and hyperthermia-treated experimental choroidal melanoma. MS 325 was used as new intravascular albumin-bound gadolinium-based contrast agent. Pigmented choroidal melanomas were established in albino rabbits. MRI was performed in 7 untreated eyes and 7 eyes treated with a Neodymium:Yttrium-Lanthanum-Fluoride-laser at 1047 nm. 3D-spoiled gradient echo pulse sequences were used to acquire T' weighted axial images. First, a set of images was collected without contrast agent. MS 325 was then injected i.v. and images were obtained within 12 min after injection. Signal intensities were measured within tumor, ciliary body, choroid, and iris and relative signal intensities were determined for these tissues in relation to vitreous. In untreated tumors, the relative signal intensity was higher after injection of MS 325 (5.61+0.70) than without MS 325 (2.90+0.33; p = 0.0002). In contrast, the relative signal intensity of treated tumors did not differ significantly before and after MS 325 (6.19+1.59 and 6.13+1.64). Histopathological sections indicated vascular occlusion in treated tumors. All other studied tissues of untreated and treated eyes showed a significant increase of relative signal intensities in the presence of MS 325. An animal model for the research on contrast agents in MRI is presented. Blood volume measurement with MS 325 was adapted for experimental choroidal melanomas. Reduced change of relative signal intensity indicates compromised blood volume after vascular occlusion in hyperthermia-treated melanoma. Further studies are needed to investigate whether this technique allows the evaluation of tumor viability following treatments.     

Modeling language evolution: Aromanian,an endangered language in Greece

Time evolution of the relative density of speakers of an endangered language, Aromanian, which is spoken by a bilingual community in North-Western Greece, is approached theoretically by means of a two-state model and a three-state model. The same prestige and volatility parameters are used in these two models. Furthermore, a culture parameter and a second exponent are introduced in the three-state model. The parameters of each model are fitted to the current status of Aromanian, on the basis of field evidence collected by us, and the first findings about the risk of the language’s extinction are presented.     

A new rhodium complex with a nitrogen‐containing bis(phosphine oxide) ligand as an efficient catalyst for the hydroformylation of styrene

A new rhodium complex with a nitrogen‐containing bis(phosphine oxide) ligand has been synthesized. The complex was applied to hydroformylation of styrene and displayed high activity and regioselectivity towards the branched aldehyde, which was found to be higher than those of the tertiary bis(phosphine) analogue. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparison of the thermal behavior and conformational changes in partially and fully hydrated dipalmitoylphosphatidylcholine systems

The temperature dependence of conformational changes for partially and fully hydrated DPPC systems through two physicochemical techniques, namely DSC and Raman spectroscopy, is studied. DSC experiments have shown a different thermal behavior between the two considered systems, indicating the effective role of water in the thermal behavior. A temperature resolution of inter- and intramolecular interactions during the main melting phase transition was achieved by using three different Raman intensity ratios, which confirm that the main phase transition represents a two-stage transition. Van’t Hoff plots for the C–C, C–H, C=O and C₄N⁺ stretching modes, in a temperature range just below the main transition temperature, have been used to compare the thermodynamic parameters extracted by the two physicochemical techniques. The significance of these results can be summarized as follows: (a) DSC and Raman spectroscopy have shown complementary results indicating that DPPC exists in partially or fully hydrated states; (b) thermodynamic parameters ΔΗ and ΔS calculated in both techniques for the two different hydration states of DPPC were in harmony; (c) water more significantly affects the thermal and dynamic properties of fully hydrated DPPC bilayers than of the partially hydrated DPPC; and (d) water disturbs the head-group packing, the alkyl chains interactions and the mesophase region. It appears that the amount of water plays a vital role in the bilayer structure. As more and more extensive studies appear in the literature on biomolecules or drug membrane interactions, this information will be valuable in understanding the role of water in these interactions.