Acquisition of Maltose Chemotaxis in Salmonella typhimurium by the Introduction of the Escherichia coli Chemosensory Transducer Gene

Escherichia coli and Salmonella typhimurium are closely related species. However, E. coli cells show maltose chemotaxis but S. typhimurium cells do not. When an E. coli chemotransducer gene (tar_E), the product of which is required for both aspartate and maltose chemotaxis, was introduced by using a plasmid vector into S. typhimurium cells with a defect in the corresponding gene (tar_S), the transformant cells acquired the ability for both aspartate and maltose chemotaxis. In contrast, when the tar_s gene was introduced into tar_E-deficient E. coli cells, the transformant cells acquired aspartate chemotaxis but not maltose chemotaxis. These results indicate that the absense of maltose chemotaxis in S. typhimurium is a consequence of the properties of the tar_s gene product

Bulk chemical compositions of meteorites in the NIPR collection

第6回極域科学シンポジウム[OA] 南極隕石11月16日（月）　国立極地研究所１階交流アトリウ

Curation of Antarctic meteorites at the National Institute of Polar Research.

第3回極域科学シンポジウム/第35回南極隕石シンポジウム 11月29日（木） 国立国語研究所 2階講

THERMOLUMINESCENCE STUDY OF JAPANESE ANTARCTIC METEORITES XIII

第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月17日（木） 国立国語研究所 2階講

Study of tropospheric correction for intercontinental GPS common-view time transfer

Current practice is to incorporate general empirical models of the troposphere, which depend only on the station height and the elevation of the satellite, in GPS time receivers used for common-view time transfer. Comparisons of these models with a semi-empirical model based on weather measurements show differences of several nanoseconds. This paper reports on a study of tropospheric correction during GPS common-view time transfer over a short baseline of about 700 km, and three long baselines of 6400 km, 9000 km and 9600 km. It is shown that the use of a general empirical model of the troposphere within a region where the climate is similar does not affect time transfer by more than a few hundreds of picoseconds. For the long distance links, differences between the use of a general empirical model and the use of a semi-empirical model reach several nanoseconds

The most primitive CM chondrites, Asuka 12085, 12169, and 12236, of subtypes 3.0–2.8: Their characteristic features and classification

CM chondrites (CMs) are the most abundant group of carbonaceous chondrites. CMs experienced varying degrees of secondary aqueous alteration and heating that modified or destroyed their primitive features. We have studied three chondrites, Asuka (A) 12085, A 12169, and A 12236. Their modal compositions, chondrule size distributions, and bulk composition indicate that they are CMs. However, the common occurrence of melilite in CAIs and glass in chondrules, abundant Fe–Ni metal, the absence of tochilinite-cronstedtite intergrowths, and almost no phyllosilicates, all suggest that these chondrites, especially A 12169, experienced only minimal aqueous alteration. The textures and compositions of metal and sulfides, the lack of ferroan rims on AOA olivines, the compositional distribution of ferroan olivine, and the Raman spectra of their matrices, indicate that these chondrites experienced neither significant heating nor dehydration. These chondrites, especially A 12169, are the most primitive CMs so far reported. The degree of the alteration increases from A 12169, through A 12236, to A 12085. We propose the criteria for subtypes of 3.0–2.8 for CMs. A 12169, A 12236, and A 12085 are classified as subtype 3.0, 2.9, and 2.8, respectively. The oxygen isotopic composition of the Asuka CMs is consistent with these samples having experienced only a limited degree of aqueous alteration. The CM and CO groups are probably not derived from a single heterogeneous parent body. These chondrites are also of particular significance in view of the imminent return of sample material from the asteroids Ryugu and Bennu

On the Relationship between Cosmic Ray Exposure Ages and Petrography of CM Chondrites

Carbonaceous (C) chondrites are potentially the most primitive among chondrites because they mostly escaped thermal metamorphism that affected the other chondrite groups. C chondrites are chemically distinguished from other chondrites by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios vary over a wide range, in contrast to those of ordinary and enstatite chondrites which are relatively uniform. It is critical to know how many separate bodies are represented by the C chondrites. In this study we defined 4 distinct cosmic-ray exposure (CRE) age groups of CMs and systematically characterized the petrography in each of the 4 CRE age groups to determine whether the groups have significant petrographic differences with such differences probably reflecting different parent body (asteroid) geological processing, or multiple original bodies. We have reported the results of a preliminary grouping at the NIPR Symp. in 2013 [3], however, we revised the grouping and here report our new results

What Are Space Exposure Histories Telling Us about CM Carbonaceous Chondrites?

Chondrites are chemically primitive and carbonaceous (C) chondrites are potentially the most primitive among them because they mostly escaped thermal metamor-phism that affected the other chondrite groups and ratios of their major, non-volatile and most of the volatile elements are similar to those of the Sun. Therefore, C chondrites are ex-pected to retain a good record of the origin and early history of the solar system. Carbonaceous chondrites are chemically differentiated from other chondrites by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios spread over a wide range though those of ordinary and enstatite chondrites are relatively uniform. It is critical to know how many sepa-rate bodies are represented by the C chondrites. In this study, CM chondrites, the most abundant carbona-ceous chondrites, are examined. They are water-rich, chon-drule- and CAI-bearing meteorites and most of them are brec-cias. High-temperature components such as chondrules, iso-lated olivine and CAIs in CMs are frequently altered and some of them are replaced by clay minerals and surrounded by sul-fides whose Fe was derived from mafic silicates. On the basis of degrees of aqueous alteration, CMs have been classified into subtypes from 1 to 2, although Rubin et al. [1] assigned subtype 1 to subtype 2 and subtype 2 to subtype 2.6 using various petrologic properties. The classification is based on petrographic and mineralogic properties. For example, though tochilinite (2[(Fe, Mg, Cu, Ni[])S] 1.57-1.85 [(Mg, Fe, Ni, Al, Ca)(HH)2]) clumps are produced during aqueous alteration, they disappear and sulfide appears with increasing degrees of aqueous alteration. Cosmic-ray exposure (CRE) age measurements of CM chondrites reveal an unusual feature. Though CRE ages of other chondrite groups range from several Myr to tens of Myr, CMs exposure ages are not longer than 7 Myr with one-third of the CM having less than 1 Myr CRE age. For those CM chondrites that have CRE ages <1 Myr, there are two discern-able CRE peaks. Because a CRE age reflects how long a me-teorite is present as a separate body in space, the peaks pre-sumably represent collisional events on the parent body (ies) [2]. In this study we defined 4 distinct CRE age groups of CMs and systematically characterized the petrography in each of the 4 CRE age groups to determine whether the groups have significant petrographic differences, with such differences probably reflecting different parent body (asteroid) geological processing, or multiple original bodies

A combination of hard and soft templating for the fabrication of silica hollow microcoils with nanostructured walls

Hollow silica microcoils have been prepared by using functionalized carbon microcoils as hard templates and surfactant or amphiphilic dye aggregates as soft templates. The obtained materials have been characterized by electron and optical microscopy, nitrogen sorption and small angle X-ray scattering. The obtained hollow microcoils resemble the original hard templates in shape and size. Moreover, they have mesoporous walls (pore size ≈ 3 nm) with some domains where pores are ordered in a hexagonal array, originated from surfactant micelles. The obtained silica microcoils also show preferential adsorption of cationic fluorescent dyes. A mechanism for the formation of silica microcoils is proposed

Measuring the frequency of a Sr optical lattice clock using a 120-km coherent optical transfer

We demonstrate a precision frequency measurement using a phase-stabilized 120-km optical fiber link over a physical distance of 50 km. The transition frequency of the 87Sr optical lattice clock at the University of Tokyo is measured to be 429228004229874.1(2.4) Hz referenced to international atomic time (TAI). The measured frequency agrees with results obtained in Boulder and Paris at a 6*10^-16 fractional level, which matches the current best evaluations of Cs primary frequency standards. The results demonstrate the excellent functions of the intercity optical fibre link, and the great potential of optical lattice clocks for use in the redefinition of the second.Comment: 14 pages, 3 figure