Structural study of a series of layered rare-earth hydroxide sulfates

We report structure analysis of a new family of rare-earth hydroxides Ln(2)(OH)(4)SO(4)·2H(2)O (Ln = Pr, Nd, Sm, Eu, Gd, Tb) from synchrotron X-ray and electron diffraction data. Rietveld profile analysis revealed that all members were isostructural and crystallized in a face-centered monoclinic system A2/m (No. 12), in which the monoclinic angles were approximately equal to the right angle, varying from 90.387(1)° for Pr sample to 90.0718(3)° for Tb sample. The structure consisted of LnO(9) polyhedra connected by μ(3)-hydroxyl groups and μ(2)-water molecules, forming a corrugated two-dimensional layer, which was pillared by bidentated sulfate ions. This series of compounds had a supercell a' = 2a, b' = 2b because of the local orientation ordering of SO(4)(2-). Structural features along the series, such as unit-cell parameters and average Ln-O distances, represented a progressive contraction associated with the shrinking radius of the lanthanide cations from Pr to Tb.     

Chemical synthesis and application of C-terminally 5-carboxyfluorescein-labelled thymopentin as a fluorescent probe for thymopoietin receptor.

Thymopentin (TP5) is a synthetic pentapeptide fragment, which corresponds to position 32 - 36 of thymic polypeptide thymopoietin. Thymopoietin and TP5 display a variety of biological functions, including phenotypic differentiation of T cells and the regulation of immune systems. Previous chemical modification experiments suggested that there was an absolute requirement for N-terminal amino acids to maintain the biological activity of TP5. On the basis of this structure-activity relationship, we designed and synthesized the C-terminally 5-carboxyfluorescein-coupled TP5 (TP5-FAM) as a fluorescent probe for thymopoietin receptor. TP5-FAM could bind to the membrane of human lymphoid cell lines, MOLT-4 cells, in which the thymopoietin receptor is expressed. The binding is specific and saturable (K(d) = 33 microM). TP5 and human splenopentin are nearly equipotent inhibitors of TP5-FAM binding to the thymopoietin receptor, but porcine secretin did not show any significant inhibition of TP5-FAM binding to MOLT-4 cells. Thus, TP5-FAM is suggested to be a potent and biologically active ligand that would be useful for studying the binding and functional characteristics of the human thymopoietin receptor.     

Mössbauer spectroscopic study of frozen solutions of57Co using a specially designed cryostat for time differential coincidence emission Mössbauer spectroscopy of237Np

Experiments on the⁵⁷Fe Mössbauer effect in frozen solutions were carried out in order to demonstrate the capabilities of a cryostat which was developed for the emission Mössbauer spectroscopy of²³⁷Np. We confirmed the existence of an aliovalent state of⁵⁷Fe in the temperature range from 5.5 to 35 K. However, the relative amounts of Fe(II) and Fe(III) in the frozen matrix were almost constant for the temperature range from 5.5 to 150 K. The design, operation and capabilities of the cryostat are also described.     

Inhalation MR lymphography: A new method for selective enhancement of the lung hilar and mediastinal lymph nodes

On MR lymphography, a new approach to the lung hilar and mediastinal nodes was developed in an animal model. Five rabbits were made to inhale iron colloid (cideferron) that was nebulized to aerosol. Two days after inhalation of the agent, the mediastinal lymph nodes decreased in signal on SE 2000/30 and SE 2000/60 images and proved to have iron on histological evaluation, whereas the popliteal nodes did not have any iron. Experimental results indicate that inhalational administration can deliver the agent to the pulmonary lymphatic system and has the potential of lung hilar and mediastinal MR lymphography.     

Effect of pressure on the vibrational structure of insensitive energetic material 5-nitro-2,4-dihydro-1,2,4-triazole-3-one

The Raman spectra of alpha form 5-nitro-2,4-dihydro-1,2,4-triazole-3-one (alpha-NTO, space group P) were measured in a high-pressure vessel diamond anvil cell (DAC). The pressure was increased to 27.6 GPa. In general, Raman bands show a blue shift because of the nature of the molecule packing as a high-pressure effect, but some particular bands exhibited a red shift, disappearance, split, or slight shifting in our experiments. Those red-shifting bands concerning hydrogen bonds, i.e., carbonyl and amino groups, are likely to work as a stabilizer against stimuli to the molecule or crystal. This stabilizing nature might characterize the insensitivity of NTO. Molecular dynamic (MD) calculations were performed to reveal the high-pressure effect of the alpha-NTO crystal. The coordinates of individual atoms in the crystal structure were obtained using X-ray diffraction analysis. The pressure dependence of the power spectra of the correlation functions of the C=O bond length in NTO was calculated. A unique high-pressure effect of the alpha-NTO crystal was found on the power spectra. The peak frequency in the power spectrum of the C=O stretching vibration exhibited a red shift with an increase in pressure to 10.0 GPa, while the peak intensity considerably decreased under the same pressure process, because this bond length increased with an increase in pressure to 10.0 GPa. At a pressure of >20.0 GPa, a blue shift appeared. These results of the MD calculations are in good agreement with our experimental data.     

The first derivative multiple zeta values at non-positive integers

In this article, we prove some explicit results for the first derivative multiple zeta values at non-positive integers and apply them to a certain classical problem in number theory which was studied and developed by E. Hecke, A. Fujii and K. Matsumoto. Further, we consider the relation between regular values and reverse values for the multiple zeta-function via a certain functional relation.     

A Theorem for Numerical Verification on Local Uniqueness of Solutions to Fixed-Point Equations

We give a theoretical result with respect to numerical verification of existence and local uniqueness of solutions to fixed-point equations which are supposed to have Fréchet differentiable operators. The theorem is based on Banach's fixed-point theorem and gives sufficient conditions in order that a given set of functions includes a unique solution to the fixed-point equation. The conditions are formulated to apply readily to numerical verification methods.

We already derived such a theorem in [11 N. Yamamoto ( 1998 ). A numerical verification method for solutions of boundary value problems with local uniqueness by Banach's fixed-point theorem . SIAM J. Numer. Anal. 35 : 2004 – 2013 .[Crossref] , [Google Scholar]], which is suitable to Nakao's methods on numerical verification for PDEs. The present theorem has a more general form and one may apply it to many kinds of differential equations and integral equations which can be transformed into fixed-point equations.     

Fluid pressure response in poroelastic materials subjected to cyclic loading

When cyclic loading is applied to poroelastic materials, a transient stage of interstitial fluid pressure occurs, preceding a steady state. In each stage, the fluid pressure exhibits a characteristic mechanical behavior. In this study, an analytical solution for fluid pressure in two-dimensional poroelastic materials, which is assumed to be isotropic, under cyclic axial and bending loading is presented, based on poroelasticity. The obtained analytical solution contains transient and steady-state responses. Both of these depend on three dimensionless parameters: the dimensionless stress coefficient; the dimensionless frequency; and, the axial-bending loading ratio. We focus particularly on the transient behavior of interstitial fluid pressure with changes in the dimensionless frequency and the axial-bending loading ratio. The transient properties, such as half-value period and contribution factor, depend largely on the dimensionless frequency and have peak values when its value is about 10. This suggests that, under these conditions, the transient response can significantly affect the mechanical behavior of poroelastic materials.