Mössbauer study of NH4FeCl3: A quasi one-dimensional magnet

NH₄FeCl₃ is a quasi one-dimensional magnet. Mössbauer spectra of powder samples of NH₄FeCl₃ have been recorded in the temperature range 1.3 to 250 K. The structural phase change between 10 and 30 K was not accompanied by changes in the Mössbauer spectra. Apparently, the changes in the local environment of the Fe²⁺ ions are not sufficient to affect the quadrupole splitting. The Mössbauer spectrum at 1.3 K, belowT _N=1.7(2) K, is magnetically split, but cannot be fitted to just one iron site. It appears to be a superposition of at least two broadened spectra, one with an internal fieldB=4.7(1) T perpendicular to the principalz-axis of the electric field gradient, the other with zero field. The intensity for these sites was found to be 3.31. The fit is improved if slow relaxation is allowed between the two sites. Broadening of the lines starts to occur at 6 K, well aboveT _N. This has not been reported for the other members of the AFeX₃ group.     

Crystallographic report: 1,3‐Bis[(trimethylsilylmethyl)dichlorostannyl]propane, [(Me3SiCH2)Cl2Sn]2(CH2)3

The dinuclear molecule of [(Me₃SiCH₂)Cl₂Sn]₂(CH₂)₃ adopts an extended conformation and features distorted tetrahedral tin centres, with the greatest distortion manifested in the C? Sn? C angles of approximately 128 °. The distortions are ascribed to the influence of intermolecular Sn···Cl interactions. Copyright © 2002 John Wiley & Sons, Ltd.     

Regioselective synthesis of N-substituted-4-substituted isothiazolidine-1,1-dioxides

A novel and efficient synthesis of a range of racemic and enantioenriched N-substituted-4-substituted isothiazolidine-1,1-dioxides from epoxides and sulfonamides is described. The critical choice of the activating group for the cyclization event is discussed. The application of this methodology to the synthesis of N-substituted-4,5-disubstituted derivatives is also described.     

Synthesis of novel benzoxathiazepine-1,1-dioxides by means of a one-pot multicomponent reaction

A simple one-pot synthesis of benzoxathiazepine-1,1-dioxides is described. Increased yields are afforded when suitable substituents are present in one of the starting materials. These additional substituents also provide a handle for further functionalization.     

A discharge adaptor interface for use in liquid chromatography/mass spectrometry

A discharge adaptor, composed of a metal casing and platinum (Pt) wire needle, was directly attached to an electrospray ionization (ESI) probe tip, to transform the ionization into atmospheric pressure chemical ionization (APCI). Six generic drugs were analyzed with the developed discharge adaptor (DA) and two commercial interfaces. The DA interface produced more intense radical anions, [M]^.–, and less sodium adduct ions, [M + Na]⁺, than the ESI interface, whereas almost the same molecular ions were detected as the APCI interface. The effects of solvent and desolvation gas flow in the DA interface were similar to those in the ESI interface, but differed from those in the APCI interface. Better sensitivity of the tested drugs was obtained relative to the commercial APCI interface. For human plasma samples, the DA interface also demonstrated good tolerance to plasma matrices, linearity from 5 or 20 to 500 ng/mL (r² > 0.99) and ruggedness. Copyright © 2011 John Wiley & Sons, Ltd.     

Three‐dimensional quadratic nonconforming brick element

A new nonconforming brick element with quadratic convergence for the energy norm is introduced. The nonconforming element consists of on a cube [?1,1]³, and 14 degree of freedom (DOF). Two types of DOF are introduced. One consists of the value at the eight vertices and six face‐centroids and the other consists of the value at the eight vertices and the integration value of six faces. Error estimates of optimal order are derived in both broken energy and norms for second‐order elliptic problems. If a genuine hexahedron, which is not a parallelepiped, is included in the partition, the proposed element is also convergent, but with a lower order. Copyright © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 158–174, 2014     

Rapid Formation of the Textured (Bi,Pb)2(Sr,Ca)4Cu3Oy Superconductor by Multiple Pressing and Sintering Process

A superconducting (Bi, Pb)₂(Sr, Ca)₄Cu₃O₂ material has been prepared by tbe oxalate coprecipitation method. The high-Tc 110 K phase was effectively promoted by application of an intermediate grinding and pressing between the sintering heat treatments. The powder X-ray diffraction shows the existence of single high-Tc and high-textured microstructures with strong (001) reflections within a short sintering time ( 18 h). The morphology of the sintered samples was examined by scanning electron microscopy (SEM). Also, the kinetics of the formation of the high-Tc phase were investigated by the isothermal method. A possible mechanism of the formation of high-Tc 2223 phase was proposed.