Influence of local structure on magnetic properties of layered cobaltites PrBaCo2O(5+δ), δ > 0.5.

The effect of local structure on the magnetic and transport properties of the layered perovskites has been investigated. The samples PrBaCo(2)O(5+δ), (δ = 0.80 and 0.67) crystallize in the same 112 type tetragonal structure but have different magnetic ground states. Extended x-ray absorption fine structure (EXAFS) spectroscopy has been employed to explain the changes in magnetic interactions based on the rotation and tilting of CoO polyhedra in these oxygen-rich double perovskites.

Photoluminescence from exciton-polarons in GaGdN/AlGaN multiquantum wells.

Exciton-polaron formation in GaGdN/AlGaN multiquantum wells was inferred from the lower energy of the photoluminescence peak observed for the GaGdN quantum wells (QWs) compared with GaN QWs. The rather low value of the excitonic transition energy is attributed to exciton-polarons bound to the Gd ions. Exciton-polarons are most likely to occur due to the lattice distortion around the substituted Gd ions in addition to the exchange interaction between Gd(3+) magnetic ions and the strongly confined charge carrier spins in GaGdN QWs. The mechanism of exciton-polaron formation is discussed. The magnetic behavior is briefly presented.

Age- and gender-dependent changes in three-dimensional microstructure of cortical and trabecular bone at the human femoral neck.

UNLABELLED: We investigated age- and gender-related variation of both cortical and trabecular microstructure in human femoral neck. We found that age-related change of cortical porosity is more noticeable than that of trabecular parameter. Our data may help to gain more insight into the potential mechanism of osteoporotic femoral neck fractures. INTRODUCTION: Variations in the microstructure of cortical and trabecular bone contribute to decreased bone strength. Age- and gender-related changes in cortical and trabecular microstructure of femoral neck is unclear. The aim of this study was to identify three-dimensional (3D) microstructural changes of both cortical and trabecular bone simultaneously in human femoral neck with age and gender, using micro-computed tomography (micro-CT). We hypothesized that there would be differences in age-related changes of cortical and trabecular bone for both women and men. METHODS: We used 56 femoral necks of 28 women and men (57-98 years of age) from a Japanese population. The subjects were chosen to give an even age and gender distribution. Both women and men were divided into three age groups: middle (57-68 years), old (72-82 years), and elderly (87-98 years) groups. We examined cortical bone specimen from the inferior sector of femoral neck and trabecular bone specimen from the middle of femoral neck using micro-CT and 3D bone analysis software. RESULTS: Cortical thickness (Ct.Th) decreased by 10-15%, cortical porosity (Ca.V/TV) almost doubled, and canal diameter (Ca.Dm) increased by 65-77% between the middle-aged and elderly groups for both women and men. The trabecular bone volume fraction (BV/TV) decreased by around 20%; trabecular thickness (Tb.Th), trabecular number (Tb.N), and connectivity density (Conn.D) decreased; and trabecular separation (Tb.Sp) and structure model index (SMI) increased with age for both women and men. As compared with women, men had higher Ct.Th and BV/TV and lower Ca.V/TV and Ca.Dm among three age groups. There was a significant inverse correlation between Ca.V.TV and BV/TV for both women and men. CONCLUSION: Our findings indicate that Ct.Th and BV/TV decreased, and Ca.V/TV and Ca.Dm increased in femoral neck with age for both women and men. The most obvious age-related change is the increase of Ca.V/TV. The decrease of BV/TV with age is more noticeable than that of Ct.Th. This is the first study that has provided both cortical and trabecular microstructural data simultaneously in a Japanese sample. These data may help us to gain more insight into the potential mechanism of osteoporotic femoral neck fractures.

Formation of aligned CrN nanoclusters in Cr-delta-doped GaN.

Cr-delta-doped GaN layers were grown by radio-frequency plasma-assisted molecular-beam epitaxy on GaN template substrates. Cr flux was supplied without nitrogen flow during Cr-delta-doping. Cr incorporation into a narrow thin layer region was confirmed with the depth profile measured by secondary ion mass spectrometry. Structural properties and Cr atom alignments were studied with transmission electron microscopy. It was found that Cr-delta-doped GaN layers were coherently grown with Cr or CrGa nanoclusters in the delta-doped region for low temperature growth (350, 500 °C). It was also found that aligned CrN nanoclusters (approximately 5 nm vertical thickness) with NaCl-type structure were formed in the delta-doped region for the growth at 700 °C.

Scanning electron microscopic study of the tongue in the owl (Strix uralensis).

The dorsal lingual surfaces of adult owl (Strix uralensis) were examined by scanning electron microscopy. The length of the tongue was about 2 cm. The tip of the tongue of the owl was bifid. Three parts were distinguished in the tongue of the owl: the apex, the body and the root of the tongue. The conical region between the lingual apex and lingual root was a very wide area. There were thread-shaped processes/cells of epithelium in the lingual apex. The small or large conical papillae were observed on the lingual body. The many openings of the lingual glands existed in the lingual body and lingual root.

Regional variations of vertebral trabecular bone microstructure with age and gender.

UNLABELLED: The vertebral trabecular bone has a complex three-dimensional (3D) microstructure, with inhomogeneous morphology. A thorough understanding of regional variations in the microstructural properties is crucial for evaluating age- and gender-related bone loss of the vertebra, and may help us to gain more insight into the mechanism of the occurrence of vertebral osteoporosis and the related fracture risks. INTRODUCTION: The aim of this study was to identify regional differences in 3D microstructure of vertebral trabecular bone with age and gender, using micro-computed tomography (micro-CT) and scanning electron microscopy (SEM). METHODS: We used 56 fourth lumbar vertebral bodies from 28 women and men (57-98 years of age) cadaver donors. The subjects were chosen to give an even age and gender distribution. Both women and men were divided into three age groups, 62-, 77- and 92-year-old groups. Five cubic specimens were prepared from anterosuperior, anteroinferior, central, posterosuperior and posteroinferior regions at sagittal section. Bone specimens were examined by using micro-CT and SEM. RESULTS: Reduced bone volume (BV/TV), trabecular number (Tb.N) and connectivity density (Conn.D), and increased structure model index (SMI) were found between ages 62 and 77 years, and between ages 77 and 92 years. As compared with women, men had higher Tb.N in the 77-year-old group and higher Conn.D in the 62- and 77-year-old groups. The central and anterosuperior regions had lower BV/TV and Conn.D than their corresponding posteroinferior region. Increased resorbing surfaces, perforated or disconnected trabeculae and microcallus formations were found with age. CONCLUSION: Vertebral trabeculae are microstructurally heterogeneous. Decreases in BV/TV and Conn.D with age are similar in women and men. Significant differences between women and men are observed at some microstructural parameters. Age-related vertebral trabecular bone loss may be caused by increased activity of resorption. These findings illustrate potential mechanisms underlying vertebral fractures.

Morphological changes of skeletal muscle, tendon and periosteum in the senescence-accelerated mouse (SAMP6): a murine model for senile osteoporosis.

SAMP6, a substrain of senescence-accelerated mouse, was developed as an animal model for senile osteoporosis. Previously we observed age-related changes of the bone in SAMP6. In the present study, we investigated the morphology of the skeletal muscle, tendon and periosteum in SAMP6 and age-matched normal mouse SAMR1. We did not find any significant differences between SAMR1 and SAMP6 at 1 and 2 months of age. As compared with SAMR1, the cross-sectional area of type I and type II muscle fibers of the soleus muscle were significantly low in SAMP6 at 8 months of age. The projections in the interface of the muscle-tendon junctions were significantly decreased in SAMP6 at 8 months of age. The number of fibroblasts and the diameter of the tendon collagen fibers in Achilles fiber were significantly reduced in SAMP6 at 8 months of age. The diameter of Sharpey's fiber reduced in SAMP6 at 5 and 8 months of age. Some chondrocytes in the insertions of Achilles tendon and some osteogenic cells in the periosteum showed degenerative changes in SAMP6 at 5 and 8 months of age. The pronounced degenerative changes were detected in the skeletal muscle, muscle-tendon junction, tendon, tendon-bone interface and periosteum in SAMP6 with age. These findings indicated the atrophy of skeletal muscle, degeneration of tendon and periosteum in SAMP6, which may be involved in the bone loss for senile osteoporosis.

Ultrastructure of the water-clear cell in the parathyroid gland of SAMP6 mice.

Although the parathyroid water-clear cell is very rare, it has clinical significance because of its association with parathyroid hyperplasia or adenoma. SAMP6, a substrain of senescence-accelerated mouse, was developed as an animal model for senile osteoporosis. We investigated the morphology of the parathyroid glands in SAMP6 and age-matched normal mouse SAMR1. The parathyroid water-clear cells, which contained numerous vacuoles and the crystalloid inclusions, were found in SAMP6 mice at 5, 8 and 12 months of age. It was noted that the number of water-clear cells increased with aging, which are fairly consistent with the change of the serum parathyroid hormone (PTH) level. We did not find any water-clear cells in the parathyroid glands of SAMR1 mice. The existence of water-clear cells may represent hyperfunction of the parathyroid glands in SAMP6.

Nerve fibres in the parathyroid gland of the golden hamster (Mesocricetus auratus): immunohistochemical and ultrastructural investigations.

We investigated the morphology and the distribution of the nerve fibres in golden hamster (Mesocricetus auratus) parathyroid glands using antibodies to calcitonin gene-related peptide (CGRP) and substance P, and electron microscopy. CGRP-immunoreactive nerve fibres were densely distributed in the interstitial tissues and the capsules of the hamster parathyroid glands. Some nerve fibres were detected in close proximity of the parathyroid chief cells. The distribution pattern for substance P-immunoreactive nerve fibres was roughly the same as for CGRP-immunoreactive fibres. Ultrastructurally, we found numerous nerve fibres joining the blood vessels. Axon bundles were located adjacent to the smooth muscle cells of the arterioles. The axons formed structurally specialized neuromuscular junctions with the vascular smooth muscle cells. Some axons were in close vicinity to the parathyroid chief cells. These findings indicate that the hamster parathyroid gland contain CGRP and substance P, which may regulate the blood flow and the secretory activity of the gland.

Morphological study of the parathyroid gland and thyroid C cell in senescence-accelerated mouse (SAMP6), a murine model for senile osteoporosis.

SAMP6, a substrain of senescence-accelerated mouse, was developed as an animal model for senile osteoporosis. We investigated the morphology of the parathyroid gland and thyroid C cell, together with the serum parathyroid hormone (PTH) and calcitonin (CT) in SAMP6 and age-matched normal mice SAMR1. We did not find any significant differences between SAMR1 and SAMP6 at 1 month of age with regard to the serum PTH level and the morphology of the parathyroid glands. As compared with SAMR1, the serum PTH level was significantly higher in SAMP6 at 2, 5 and 12 months of age. In the parathyroid chief cells of SAMP6 at 2, 5 and 12 months of age, the Golgi complexes and the cisternae of the granular endoplasmic reticulum were well developed. Numerous secretory granules were located near the plasma membranes and mitoses were sometimes observed. There was no marked difference between SAMR1 and SAMP6 regarding the morphology of the thyroid C cells and the serum CT level. These findings suggest that the secretory activity of the parathyroid gland is stimulated in SAMP6 at 2, 5 and 12 months of age. The parathyroid follicle was sometimes found in SAMP6, and the significance of this structure was also discussed.

Ultrastructural changes in bones of the senescence-accelerated mouse (SAMP6): a murine model for senile osteoporosis.

SAMP6, a substrain of senescence-accelerated mice, was developed as an animal model for senile osteoporosis. In the present study, we investigated the bone morphology, together with serum calcium and bone mineral density (BMD) in SAMP6 and age-matched normal mice SAMR1. We did not find any significant differences between SAMR1 and SAMP6 at 1 month of age with regard to the serum compositions and bone morphology. As compared with SAMR1, BMD, the femoral weight, femoral calcium and phosphorus levels were significantly reduced in SAMP6 at 2 and 5 months of age. The number of osteoblasts in trabecular bones was also significantly reduced. Swollen mitochondria and myelin-like structures were found in osteoblasts and osteocytes of SAMP6 mice at 2 and 5 months of age. There was a greater proportion of resting surface and less forming surface in the femoral endosteal surfaces of SAMP6 mice. The amount of trabecular bone in the lumbar vertebra and the distal metaphysis of the femur was reduced. The number of the mast cells in bone marrow of the tibia significantly increased in SAMP6 mice. These findings indicate that the lower bone mass in SAMP6 was due to the reduction in osteoblast formation and suggested that mast cells in bone marrows play a role in the pathogenesis of senile osteoporosis.

Morphology of the dorsal lingual papillae in the Japanese macaque and Savanna monkey.

The dorsal lingual surfaces of infant Japanese macaque (Macaca fuscata) and adult savanna monkey (Cercopithecus aethiopus) were examined by scanning electron microscopy. Filiform, fungiform, foliate and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue. The fungiform papillae were round in shape, and more densely distributed on the lingual apex. The foliate papillae were seen on the dorsolateral aspect of the tongue. The three vallate papillae were arranged like a triangle with the apex of the triangle directing caudally. Each papilla was surrounded by a groove. The rudiments of the fungiform, foliate and vallate papillae were visible earlier than those of the filiform papillae.

Effect of low or high dietary calcium on the morphology of the rat femur.

The present study compared the effect of a calcium deficit or surfeit on femurs. Young female rats were fed with the normal (1.18%), low (0.05%), or high (2.00%) calcium diet for 3, 7, 15 or 30 days. Two groups received the low calcium diet for the first 15 days and then were followed by the normal (L-N) or high calcium diets (L-H) for the sequential 15 days. The morphology of the femur was studied together with serum calcium, parathyroid hormone (PTH), calcitonin and bone mineral density (BMD). We did not find any significant changes in the serum PTH level and bone morphology in the high calcium group. In the low calcium group, the serum PTH level increased, BMD of the whole body, the femoral weight and the femoral trabecular bone decreased as compared with the normal calcium group. There was a greater proportion of resorbing surface, less resting surface and larger vascular canal openings in the femoral endosteal surfaces in the low calcium group. In the L-N or L-H group, the femoral trabecular bone increased and the femoral resorbing surface decreased as compared with those of the low calcium group. These findings suggest that high calcium intakes do not affect the bone mass, and low calcium intakes have a deleterious effect on bone status, which may be related to vascular alternations of the bone. Reversing the low income calcium intake by a higher calcium diet can partially improve the bone alternations induced by low calcium intake.

Effects of cigarette smoke exposure on the ultrastructure of the golden hamster parathyroid gland.

Cigarette smoking has been identified as one of the risk factors to induce osteoporosis. However, we find no study on the morphology of the parathyroid gland under smoking exposure. We studied the ultrastructure of the parathyroid gland, lung and femur of the golden hamster exposed to cigarette smoke. Four-week-old male hamsters were housed in a plastic case (48x31x30 cm) and were exposed to cigarette smoke for 12 weeks, 5 minutes exposure, 4 times a day, 4 days a week. There were no differences in serum calcium level and the whole bone mineral density between the control and the smoke-exposed groups. In the parathyroid gland of the smoke-exposed animals, the Golgi complexes associated with many prosecretory granules were well developed and many secretory granules were located near the plasma membrane. Large lipid-like inclusion bodies were observed in the alveolar macrophages of the smoke-exposed animals. The femur morphology showed a wider area of resorbing surface in the smoke-exposed group than in the control group. From these findings, it is conceivable that the secretory activity of the parathyroid gland was stimulated with cigarette smoke exposure.

Double electron transitions [MN] or [MO] above 74W MIII edge in X-ray absorption spectra.

The x-ray absorption spectra in metallic W (Tungsten) have been measured above MIII edge using the third generation synchrotron radiation. ALS, Berkeley. Several features caused by multi-electron transitions were detected on MIII in solid phase. [3p4f], [3p5s], and [3p5p] double electron transitions were identified by the Z+1 approximation.

EXAFS spectra above Pb and Pt K edges observed at low temperature.

X-ray absorption spectra near K edges of Pb (88.0keV) and Pt (78.4keV) for the foils were measured in transmission mode at SPring-8. We succeeded for the first time in observing the EXAFS oscillation of the Pb foil at 12K, although it was failed at room temperature in a previous experiment. The amplitude of the EXAFS oscillation of the Pt foil at 12K considerably increased in comparison with that at room temperature, indicating that the amplitude is very sensitive to the Debye-Waller factor at high-k values.

XAFS study on metal endohedral fullerenes.

Structure of metal endohedral fullerenes is studied by XAFS and XANES. The Sc-Sc distance of 2.23(1) A determined from Sc K-edge XAFS supports the formation of a triangular Sc3 cluster in Sc3@C82 as is found by MEM analysis for the X-ray diffraction. Gd L(III)-edge XAFS of Gd@C82 shows that the first and the second neigboring Gd-C distances are 2.51(2) and 2.85(4) A, respectively. The La-La distance of La2@C80 has been determined to be 3.90(1) A at 40 K. This value does not change when increasing temperature [3.90(2) A at 240 K]. The position and the valenece of the Eu atom in Eu@C60 are also discussed based on Eu L(III)-edge XAFS and XANES.

XAFS study on a pressure-induced superconductor Cs3C60 under high pressure.

Cs K-edge XAFS of Cs3C60 which is a pressure-induced superconductor were measured at 21 and 34 kbar by using a diamond anvil cell (DAC) in order to obtain the structural information under high pressure, and to clarify the origin of the pressure-induced superconductivity. The distances and the mean square displacements between the Cs and C atoms are consistent with those determined by X-ray powder diffraction. Consequently, the high-pressure XAFS can give the reliable structural-information on a fullerene superconductor under high pressure. We also show the procedure of the analysis of high-pressure XAFS with DAC in detail.

Study on local structure around Ce and Gd atoms in CeO2-Gd2O3 binary system.

X-ray absorption spectra near Ce and Gd K-edges of binary oxide of Ce(x)Gd(1-x)O(3+x)/2 (0 < or = x < or = 0.5) in C-type structure solid solution were measured by use of the beamline BL01B1 at SPring-8. Interatomic distances between rare-earth and oxygen atoms. R(Gd-O) and R(Ce-O), were evaluated with the extended x-ray absorption fine structure analysis and found to increase with x. R(Gd-O) was larger than R(Ce-O) by about 0.1 A. Metal-oxygen distances estimated as their linear combinations, xR(Ce-O) + (1-x)R(Gd-O), well agreed with those determined by X-ray diffraction.

EXAFS study of Sb-Te alloy films.

The local structures of three phases; stable compound Sb2Te3, metastable crystalline c-SbTe and amorphous a-SbTe films having the atomic ratio Sb/Te=3: in Sb-Te system have been studied by EXAFS. The c-SbTe has a partly similar local structure to crystalline Sb2Te3. The a-SbTe film has a local structure of NaCl-type, which is topologically analogous to the crystalline form. The amorphous phase has shorter bond distances 2.86A (around Sb-site) and 2.83A (around Te-site) than the corresponding distances 2.89A and 2.87A in the crystalline phase. This unbalanced bond distances between the Sb-site and Te-site implies that site-disordering occurs. Shortening of bond distances in the amorphous phase is due to the relaxation of locally distorted crystalline structure.