A new synthetic route to 7 α-methoxycephalosporins

Treatment of 7β-(2,2,3-trihaloalkylideneamino) cephalosporins with excess methanol in the presence of acid scavenger gave 7β-(2-haloalk-2-enylideneamino)-7α-methoxycephalosporins.     

Anomalous pressure effect on the resistivity minimum in antiferromagnetic Cr-0.6 at.%Fe alloy

The electrical resistivity of Cr-0.6 at.%Fe alloy which has an incommensurate spin density wave state has been measured in the temperature range from 4.2 K to room temperature under pressures p to 18.6 kbar. The Néel temperature is found to decrease with pressure at a rate of 5.4± 0.3K/bar, and the depth of the minimum also is found to increase greatly with pressure. These results can be explained qualitatively from the point of view that the resistivity minimum is caused by the Kondo effect.     

Models and Inference for Corrosion Pit Depth Data

A new regression structure is introduced to several families of distributions, including the Generalized Extreme Value (GEV) distribution, which are available to explain the distribution of the maximum pit depth of a small sample. This regression structure depends on sample sizes, but under a simple assumption it is also available in the case of unknown sample sizes. GEV with the proposed regression structure provides us with a new extrapolation model for time. Compared to ordinary GEV models, effectiveness of our GEV model is demonstrated for our real data set. Also, comparisons are made with GEV and other two families of distributions with respect to the proposed regression structure.     

Precise determination of dissolved silica in seawater by ion-exclusion chromatography isotope dilution inductively coupled plasma mass spectrometry

Ion exclusion chromatograph (IEC) isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP–MS) (IEC–ID–ICP–MS) was developed for measurement of dissolved silica in seawater, which was applied to production of certified reference materials (CRMs) of three concentration levels of nutrients (high, medium and low levels). IEC–ICP–MS has been employed to separate dissolved silica from seawater matrix. In the present study, in order to solve substantial problems due to spectral interference in ICP–MS and to improve the accuracy of IEC–ICP–MS beyond standard addition or conventional calibration methods, ID method was coupled with ICP-sector field mass spectrometry (operated under medium resolution,i.e., m/Δm = 4000). In addition, effects of various operating parameters in ICP–MS on a silicon background level were also investigated to obtain lower background equivalent concentration (BEC). As a result, 3 ng g⁻¹ of the BEC and 0.5 % of relative standard uncertainties were achieved in the analyses of dissolved silica in seawater samples at concentration levels from 4.0 mg kg ^-1 to 0.8 mg kg⁻¹ as silicon. The developed method was successfully validated by analyses of an artificial seawater containing a known amount of silicate and the seawater certified reference material MOOS-2 produced by the National Research Council Canada.     

Proton Conductivities of Graphene Oxide Nanosheets: Single,Multilayer, and Modified Nanosheets

Proton conductivities of layered solid electrolytes can be improved by minimizing strain along the conduction path. It is shown that the conductivities (σ) of multilayer graphene oxide (GO) films (assembled by the drop‐cast method) are larger than those of single‐layer GO (prepared by either the drop‐cast or the Langmuir‐Blodgett (LB) method). At 60 % relative humidity (RH), the σ value increases from 1×10⁻⁶ S cm⁻¹ in single‐layer GO to 1×10⁻⁴ and 4×10⁻⁴ S cm⁻¹ for 60 and 200 nm thick multilayer films, respectively. A sudden decrease in conductivity was observed for with ethylenediamine (EDA) modified GO (enGO), which is due to the blocking of epoxy groups. This experiment confirmed that the epoxide groups are the major contributor to the efficient proton transport. Because of a gradual improvement of the conduction path and an increase in the water content, σ values increase with the thickness of the multilayer films. The reported methods might be applicable to the optimization of the proton conductivity in other layered solid electrolytes.     

Local Uniformization and Free Boundary Regularity of Minimal Singular Surfaces

We continue the study of minimal singular surfaces obtained by a minimization of a weighted energy functional in the spirit of J. Douglas’s approach to the Plateau problem. Modeling soap films spanning wire frames, a singular surface is the union of three disk-type surfaces meeting along a curve which we call the free boundary. We obtain an a priori regularity result concerning the real analyticity of the free boundary curve. Using the free boundary regularity of the harmonic map, we construct local harmonic isothermal coordinates for the minimal singular surface in a neighborhood of a point on the free boundary. Applications of the local uniformization are discussed in relation to H. Lewy’s real analytic extension of minimal surfaces.     

Tetraspanin CD9 modulates ADAM17-mediated shedding of LR11 in leukocytes

LR11, also known as SorLA or SORL1, is a type-I membrane protein from which a large extracellular part, soluble LR11 (sLR11), is released by proteolytic shedding on cleavage with a disintegrin and metalloproteinase 17 (ADAM17). A shedding mechanism is presumed to have a key role in the functions of LR11, but the evidence for this has not yet been demonstrated. Tetraspanin CD9 has been recently shown to regulate the ADAM17-mediated shedding of tumor necrosis factor-α and intercellular adhesion molecule-1 on the cell surface. Here, we investigated the role of CD9 on the shedding of LR11 in leukocytes. LR11 was not expressed in THP-1 monocytes, but it was expressed and released in phorbol 12-myristate 13-acetate (PMA)-induced THP-1 macrophages (PMA/THP-1). Confocal microscopy showed colocalization of LR11 and CD9 proteins on the cell surface of PMA/THP-1. Ectopic neo-expression of CD9 in CCRF-SB cells, which are LR11-positive and CD9-negative, reduced the amount of sLR11 released from the cells. In contrast, incubation of LR11-transfected THP-1 cells with neutralizing anti-CD9 monoclonal antibodies increased the amount of sLR11 released from the cells. Likewise, the PMA-stimulated release of sLR11 increased in THP-1 cells transfected with CD9-targeted shRNAs, which was negated by treatment with the metalloproteinase inhibitor GM6001. These results suggest that the tetraspanin CD9 modulates the ADAM17-mediated shedding of LR11 in various leukemia cell lines and that the association between LR11 and CD9 on the cell surface has an important role in the ADAM17-mediated shedding mechanism.     

Superconducting Double Perovskite Bismuth Oxide Prepared by a Low‐Temperature Hydrothermal Reaction

Perovskite‐type structures (ABO₃) have received significant attention because of their crystallographic aspects and physical properties, but there has been no clear evidence of a superconductor with a double‐perovskite‐type structure, whose different elements occupy A and/or B sites in ordered ways. In this report, hydrothermal synthesis at 220 °C produced a new superconductor with an A‐site‐ordered double perovskite structure, (Na_0.25K_0.45)(Ba_1.00)₃(Bi_1.00)₄O₁₂, with a maximum T_c  of about 27 K.     

Mössbauer spectroscopic study on glaze of pottery

Iron-barium glaze was prepared from commercially available materials for ceramic arts and from chemical reagents, and investigated by means of Mössbauer spectroscopy and an electron probe micro analyzer (EPMA). Mössbauer spectra showed a doublet of paramagnetic high-spin Fe(II) and Fe(III) incorporated into aluminosilicate, and the magnetically-split hyperfine structures of hematite and magnetite, depending on the iron content and firing conditions. The EPMA indicated striped patterns on the secondary electron images, and the fluorescent X-ray analysis proved that the patterns are due to the heterogeneous distribution of elements in the glaze.