1,052 research outputs found
Low-Temperature X-ray Crystal Structure Analysis of the Cage-Structured Compounds MBe13 (M = La, Sm, and U)
The beryllides MBe13 (M = rare earths and actinides) crystallize in a
NaZn13-type cubic structure, which can be categorized as a cage-structured
compound. In this study, powder X-ray diffraction measurements have been
performed on LaBe13, SmBe13, and UBe13 in the temperature range between 7 and
300 K in order to investigate their crystallographic characteristics
systematically. They keep the NaZn13-type cubic structure down to the lowest
temperature. We estimated their Debye temperature to be 600 - 750 K from
analyses of the temperature dependence of a lattice parameter, being in good
agreement with the values reported previously. Rietveld refinements on the
obtained powder patterns revealed that the M atom in the 8a site is located in
an almost ideal snub cube formed by 24 Be atoms in the 96i site, whose caged
structure is unchanged even at the low temperatures. In addition, it is argued
from the temperature variation of an isotropic mean-square displacement
parameter that the MBe13 compounds commonly have a low-energy phonon mode,
which can be described by a model assuming an Einstein oscillation of the M
atom with a characteristic temperature of ~ 160 K.Comment: 8 pages with 6 figures and 2 table
Impact of polyplex micelles installed with cyclic RGD peptide as ligand on gene delivery to vascular lesions
Gene therapy is expected to open a new strategy for the treatment of refractory vascular diseases, so the development of appropriate gene vectors for vascular lesions is needed. To realize this requirement with a non-viral approach, cyclo(RGDfK) peptide (cRGD) was introduced to block copolymer, poly(ethylene glycol)-block-polycation carrying ethylenediamine units (PEG-PAsp(DET)). cRGD recognizes αvβ3 and αvβ5 integrins, which are abundantly expressed in vascular lesions. cRGD-conjugated PEG-PAsp(DET) (cRGD-PEG-PAsp(DET)) formed polyplex micelles through complexation with plasmid DNA (pDNA), and the cRGD-PEG-PAsp(DET) micelles achieved significantly more efficient gene expression and cellular uptake as compared with PEG-PAsp(DET) micelles in endothelial cells and vascular smooth muscle cells. Intracellular tracking of pDNA showed that cRGD-PEG-PAsp(DET) micelles were internalized via caveolae-mediated endocytosis, which is associated with a pathway avoiding lysosomal degradation, and that PEG-PAsp(DET) micelles were transported to acidic endosomes and lysosomes via clathrin-mediated endocytosis. Further, in vivo evaluation in rat carotid artery with a neointimal lesion revealed that cRGD-PEG-PAsp(DET) micelles realized sustained gene expression, while PEG-PAsp(DET) micelles facilitated rapid but transient gene expression. These findings suggest that introduction of cRGD to polyplex micelles might create novel and useful functions for gene transfer and contribute to the establishment of efficient gene therapy for vascular diseases
13CO(J=1-0) On-the-fly Mapping of the Giant HII Region NGC 604: Variation in Molecular Gas Density and Temperature due to Sequential Star Formation
We present 13CO(J=1-0) line emission observations with the Nobeyama 45-m
telescope toward the giant HII region NGC 604 in the spiral galaxy M 33. We
detected 13CO(J=1-0) line emission in 3 major giant molecular clouds (GMCs)
labeled as GMC-A, B, and C beginning at the north. We derived two line
intensity ratios, 13CO(J=1-0)/12CO(J =1-0), R13/12, and 12CO(J=3-2)/12CO(J
=1-0), R31, for each GMC at an angular resolution of 25" (100 pc). Averaged
values of R13/12 and R31 are 0.06 and 0.31 within the whole GMC-A, 0.11 and
0.67 within the whole GMC-B, and 0.05 and 0.36 within the whole GMC-C,
respectively. In addition, we obtained R13/12=0.09\pm0.02 and R31=0.76\pm0.06
at the 12CO(J=1-0) peak position of the GMC-B. Under the Large Velocity
Gradient approximation, we determined gas density of 2.8 \times10^3 cm^-3 and
kinetic temperature of 33+9-5 K at the 12CO(J=1-0) peak position of the GMC-B.
Moreover, we determined 2.5 \times10^3 cm^-3 and 25\pm2 K as averaged values
within the whole GMC-B. We concluded that dense molecular gas is formed
everywhere in the GMC-B because derived gas density not only at the peak
position of the GMC but also averaged over the whole GMC exceeds 10^3 cm^-3. On
the other hand, kinetic temperature averaged over the whole GM-B, 25 K, is
significantly lower than that at the peak position, 33 K. This is because HII
regions are lopsided to the northern part of the GMC-B, thus OB stars can heat
only the northern part, including the 12CO(J=1-0) peak position, of this GMC.Comment: 16 pages, 7 figures, PASJ in pres
NRO M33 All Disk Survey of Giant Molecular Clouds (NRO MAGiC): I. HI to H_2 Transition
We present the results of the Nobeyama Radio Observatory (NRO) M33 All Disk
(30'x30' or 7.3 kpc x 7.3 kpc) Survey of Giant Molecular Clouds (NRO MAGiC)
based on 12CO (1-0) observations using the NRO 45-m telescope. The spatial
resolution of the resultant map is 19".3, corresponding to 81 pc, which is
sufficient to identify each Giant Molecular Cloud (GMC) in the disk. We found
clumpy structures with a typical spatial scale of ~100 pc, corresponding to
GMCs, and no diffuse, smoothly distributed component of molecular gas at this
sensitivity. Closer inspection of the CO and HI maps suggests that not every CO
emission is associated with local HI peaks, particularly in the inner portion
of the disk (r < 2 kpc), although most of CO emission is located at the local
HI peaks in the outer radii. We found that most uncovered GMCs are accompanied
by massive star-forming regions, although the star formation rates (SFRs) vary
widely from cloud to cloud. The azimuthally averaged H{\sc i} gas surface
density exhibits a flat radial distribution. However, the CO radial
distribution shows a significant enhancement within the central 1-2 kpc region,
which is very similar to that of the SFR. We obtained a map of the molecular
fraction, f_mol = Sigma_H_2/(Sigma_HI+Sigma_H_2, at a 100-pc resolution. This
is the first f_mol map covering an entire galaxy with a GMC-scale resolution.
We find that f_mol tends to be high near the center. The correlation between
f_mol and gas surface density shows two distinct sequences. The presence of two
correlation sequences can be explained by differences in metallicity, i.e.,
higher (~ 2-fold) metallicity in the central region (r< 1.5 kpc) than in the
outer parts. Alternatively, differences in scale height can also account for
the two sequences, i.e., increased scale height toward the outer disk.Comment: Accepted for publication in PASJ, See
http://www.juen.ac.jp/lab/tosaki/paper/astro-ph/2011/tosaki2011.pdf for a
version with full resolution figure
Petrogenesis of ferromanganese nodules from East of the Chagos Archipelago, Central Indian Basin, Indian Ocean
Deep-sea ferromanganese nodules occur over a large area and on many different sediment types of the
Central Indian Basin, Indian Ocean. Selected samples were studied to determine their chemical and mineralogical
compositions and microstructural features. Repeated laminations of variable thickness, alternately dominated by
todorokite and vernadite, are characteristic of these nodules. These laminae show, on electron microprobe line
scans, corresponding interlaminar partitioning of Mn-Cu-Ni and Fe-Co. The bulk chemical compositions of these
nodules plot in both the hydrogenetic and early diagenetic fields on the FeāMnā(Ni + Cu + Co) Ć 10 ternary
diagram. The binary diagram depicting the covariation of Mn + Ni + Cu against Fe + Co shows two distinct parallel
regression lines, one delineated by nodules from terrigenous, siliceous ooze and siliceous oozeāterrigenous
sediments and the other by nodules from red clay, siliceous oozeāred clay and calcareous oozeāred clay. An
increasing diagenetic influence in the nodules with the nature of the host sediment types was observed in the
sequence: terrigenous ā siliceous ooze and red clay ā siliceous/calcareous oozeāred clay. A negative
correlation between Mn/Fe ratio and Co and a positive correlation between Mn/Fe ratio and (Ni + Cu) was established.
The nodules show dendritic, laminated, and globular microstructures formed by primary growth of FeāMn oxide laminae.
Depositional hiatuses in the primary microstructures indicate that the growth of these nodules was episodic. The
oxide laminations show extremely complex growth patterns. Scattered biogenic remains and mineral grains acted as
accessory 'seeds' for growth of oxide layers in addition to the main nuclei. None of the primary microstructures can
be uniquely linked to a particular growth process or growth rate. Radial cracks, cutting across primary
microstructures, are often filled by todorokite of a later generation. Post-depositional modifications of the
nodules were largely controlled by accreted biogenic remains as indicated by their progressive dissolution with
increasing depth from nodule surfaces, their pseudomorphic replacement by todorokite and the later growth of
phillipsite and todorokite in the microfossil molds. The growth patterns of the in-filled oxides are often
controlled entirely by the cavity-walls and are discordant with the primary growth fabric. Primary todorokite was
recrystallized to coarser grains of different chemical composition. Later generation veins of todorokite cut across
and chaotically disrupted primary laminae
Autoantibody with Cross-Reactivity between Insulin and Ductal Cells May Cause Diabetic Mastopathy: A Case Study
Lymphocytic mastopathy or diabetic mastopathy is a benign breast disease characterized by dense fibrosis, lobular atrophy, and aggregates of lymphocytes in a periductal and perilobular distribution. The condition usually affects women with a long history of diabetes mellitus (DM) and also those with autoimmune disorders. While the pathogenesis is unknown, a particular type of class II human leukocyte antigen has been associated with this disease. Herein, we report a case of diabetic mastopathy which clinically and radiologically mimicked primary breast neoplasms. The patient was a 74-year-old woman with a 31-year history of DM type II who presented with multiple firm lumps in bilateral breasts. Findings from mammography, ultrasonography, and magnetic resonance imaging of the breasts revealed an abnormal appearance which suspiciously resembled malignancy. An aspiration cytology specimen showed atypical accumulation of lymphoid cells, leading us to suspect lymphoma. Histology of an excisional biopsy showed the characteristic appearance of lymphocytic mastopathy, which predominantly consisted of B-lymphocytes. Autoantibodies in her serum reacted positively against her ductal epithelium as well as other diabetic and nondiabetic breast ductal cells. An antigen absorption test with insulin revealed attenuating intensity according to insulin concentration. These anti-insulin antibodies produced in the DM patient may cause ductitis because of antigen cross-reactivity
Measurement of Local Plastic Deformation in Aluminum Alloy by Means of X-ray 3D Imaging Technique
AbstractTo understand the local deformation behavior is very important for improvement of deformability in aluminum alloys which possess poor deformation limit in comparison with steels. However, measurement of local deformation in the interior of metal is not sufficiently carried out. In this study, the development of local plastic strain is measured by means of X-ray 3D imaging technique, i.e. high-resolution synchrotron X-ray microtomography. The marker tracking method, which is based on 3D image processing in volumetric image, is developed for obtaining local strains in 3D. Deformation behaviour is particularly different in individual grains. It was found that grains with different orientations deform maintaining harmony by shear deformation
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