Spectroscopic studies of acid-resistant residues of carbonaceous chondrites

Mass and IR spectra have been obtained of the acid-resistant residues resulting from HCl and HF treatments of ALH-77307 (C3). ^C NMR spectra of the residues obtained by partial mineral dissolution with acid treatments of Yamato-791717 (C3) and Allende (C3) have been recorded under CP-MAS conditions. These spectral data were compatible with the polycyclic aromatic structure proposed for the major carbonaceous matter in carbonaceous chondrites by the authors

Pyrolytic nature of carbonaceous matter in carbonaceous chondrites and secondary metamorphsm

Major carbonaceous matter in five C2 carbonaceous chondrites (Y-791198,Y-74662,Murchison, B-7904,and Y-793321) and six C3 carbonaceous chondrites (Allende, Y-790992,Y-791717,Y-81020,ALH-77003,and ALH-77307) was investigated by pyrolysis-gas chromatography. The amount of naphthalene produced on the pyrolysis varied largely from chondrite to chondrite, and the carbonaceous matter in these chondrites could be divided into five groups by the efficiency of formation of pyrolysis products. The groups did not accord with any conventional subdivisions of carbonaceous chondrites. The grouping based on the pyrolytic nature of the major carbonaceous matter may give additional information about secondary metamorphism in carbonaceous chondrites

Raman frequencies of graphitic carbon in Antarctic ureilites

Raman frequencies for the in-plane lattice vibration of graphite were surveyed for four Antarctic ureilites in order to construct a paradigm for structural properties of graphitic carbon in ureilites. Raman spectra were obtained by point-by-point measurements using a laser microbeam 1μm in diameter. The measured results formed an array in a two-dimensional plot between the E_ frequency and intensity ratio of two graphite-derived Raman bands. The graphitic matter in ALH-78019 gave the averaged E_ frequency at 1582.0 ⊿cm^, which agrees with the well-established wavenumber of the E_ in-plane lattice vibration of graphite. On the contrary, some graphitic matter in the ureilites (ALH-77257,Y-791538 and MET-78008) exhibited considerably up-shifted E_ frequency. Distribution in the array was proved to be closely linked to the extent of shock which the ureilites suffered

In-situ micro Raman studies on graphitic carbon in some Antarctic ureilites

The fine structures of graphitic materials contained in four Antarctic ureilites (ALH-77257,ALH-78019,MET-78008 and Y-791538) were investigated using a laser light (514.5nm), which could be focused onto a spot of 1μm in diameter. Raman spectra obtained differ not only among individual ureilite samples, but also among positions within a single carbonaceous vein of the same specimen. Moreover, one can classify the carbon into several groups on the basis of the spectra concerned. For all samples, both well-ordered graphitic carbon and semi-ordered graphitic carbon were observed. Amorphous carbon was detected in ALH-77257 and MET-78008. The difference in structural ordering among the samples is attributed to the difference in distribution of the components of carbonaceous material, indicating minor difference in genetic conditions or in locality within the parent body. Structural heterogeneity of carbon within a single carbonaceous vein implies the occurrence of two (or three) types of carbonaceous matters which have fairly different physicochemical properties and distinct histories. For the genesis of the carbonaceous matter in ureilites, a two-stage model is proposed assuming the graphite crystallization from metallic phase followed by the inflow of semi-ordered graphitic carbon or amorphous carbon into the well-ordered graphitic carbon produced from the metal

Excessive whole-body exposure to 28 GHz quasi-millimeter wave induces thermoregulation accompanied by a change in skin blood flow proportion in rats

IntroductionLimited information is available on the biological effects of whole-body exposure to quasi-millimeter waves (qMMW). The aim of the present study was to determine the intensity of exposure to increase body temperature and investigate whether thermoregulation, including changes in skin blood flow, is induced in rats under whole-body exposure to qMMW.MethodsThe backs of conscious rats were extensively exposed to 28 GHz qMMW at absorbed power densities of 0, 122, and 237 W/m2 for 40 minutes. Temperature changes in three regions (dorsal and tail skin, and rectum) and blood flow in the dorsal and tail skin were measured simultaneously using fiber-optic probes.ResultsIntensity-dependent temperature increases were observed in the dorsal skin and the rectum. In addition, skin blood flow was altered in the tail but not in the dorsum, accompanied by an increase in rectal temperature and resulting in an increase in tail skin temperature.DiscussionThese findings suggest that whole-body exposure to qMMW drives thermoregulation to transport and dissipate heat generated on the exposed body surface. Despite the large differences in size and physiology between humans and rats, our findings may be helpful for discussing the operational health-effect thresholds in the standardization of international exposure guidelines

A cancer stem cell model as the point of origin of cancer-associated fibroblasts in tumor microenvironment

Cancer-associated fibroblasts (CAFs) are one of the most prominent cell types in the stromal compartment of the tumor microenvironment. CAFs support multiple aspects of cancer progression, including tumor initiation, invasion, and metastasis. The heterogeneous nature of the stromal microenvironment is attributed to the multiple sources from which the cells in this compartment originate. The present study provides the first evidence that cancer stem cells (CSCs) are one of the key sources of CAFs in the tumor niche. We generated CSC-like cells by treating mouse induced pluripotent stem cells with conditioned medium from breast cancer cell lines. The resulting cell population expressed both CSC and pluripotency markers, and the sphere-forming CSC-like cells formed subcutaneous tumors in nude mice. Intriguingly, these CSC-like cells always formed heterogeneous populations surrounded by myofibroblast-like cells. Based on this observation, we hypothesized that CSCs could be the source of the CAFs that support tumor maintenance and survival. To address this hypothesis, we induced the differentiation of spheres and purified the myofibroblast-like cells. The resulting cells exhibited a CAF-like phenotype, suggesting that they had differentiated into the subpopulations of cells that support CSC self-renewal. These findings provide novel insights into the dynamic interplay between various microenvironmental factors and CAFs in the CSC niche

REE characteristics of Antarctic eucrites

Rare-earth elements (REE), Ba, Sr and Rb abundances were precisely determined for three Antarctic eucrites (ALH-78132,Y-790260 and Y-790266), Y-7308 howardite, Y-790143 LL chondrite, Pasamonte eucrite, and plagioclase and clinopyroxene fractions of the Y-790266 eucrite. A positive Ce anomaly and Yb-Lu deviation from smoothness characterize REE patterns of Antarctic eucrites. These REE features are commonly observed for Antarctic eucrites which have been analyzed thus far by us and our colleagues, employing mass-spectrometric isotope dilution method. The degrees of Ce and Yb-Lu deviations are small or substantially absent for almost all of non-Antarctic eucrites and Antarctic meteorites other than eucrites. Some discussions are given to the possible implications of the Ce anomaly and Yb-Lu deviation observed in Antarctic eucrites

REE Abundances in the Whole Rock and Mineral Separates of the Allan Hills-765 Meteorite

The rare earth elements (REE) Ba and Sr abundances in the whole rock and mineral separates of the Allan Hills-765 meteorite and in the whole rock of the Juvinas meteorite have been determined by the mass spectrometric isotope dilution method. The REE pattern of the whole rock of the Allan Hills meteorite is similar to that of the Juvinas meteorite but is different in presence of a significantly large (∿+50%) Ce anomaly. The hand-picked pyroxenes black clast show different REE patterns with different extents of Ce anomalies (-40∿+240%). On the other hand, plagioclase shows rather minor (∿+10%) Ce irregularity. REE patterns for estimated melts in equilibrium with the minerals suggest that different pyroxenes have not been in equilibrium with each other and with plagioclase

Two Major Groups of Chondritic REE Abundances Suites: Variable Octad Effect on Heavy REE

It has been found that heavy REE octad in a considerable fraction of Antarctic meteorites seems to bear a striking mutual resemblance in downward concave curvature when normalized by the Leedey chondrite. As one of possibilities, this may suggest that, in addition to the "Leedey-type" and related suites of chondritic REE abundances, there is another major group with respect to chondritic REE abundances, in particular, to heavy REE relative abundances. Alternatively, REE abundances with such a characteristic may indicate cognate relations of Antarctic meteorites studied. There appears to be a close relationship between anomalies of Eu and those of Yb

Pyrolytic studies of organic components in Antarctic carbonaceous chondrites Y-74662 and ALH-77307

The organic components of two Antarctic carbonaceous chondrites, Y-74662 (C2) and ALH-77307 (C3), have been investigated by pyrolysis using a Curie point pyrolyzer equipped with GC or GC-MS. Although a number of aromatic compounds have been detected as the pyrolysis products of Y-74662 along with a small amount of n-alkanes, only a few aromatic compounds in small quantities and no n-alkane have been detected in the components produced on the pyrolysis of ALH-77307