The interplay between superconductivity and structural phase transition has attracted enormous interest in recent years. For example, in Fe-pnictide high temperature superconductors, quantum ...fluctuations in association with structural phase transition have been proposed to lead to many novel physical properties and even the superconductivity itself. Here we report a finding that the quasi-skutterudite superconductors (Sr1−xCax)3Ir4Sn13 (x = 0, 0.5, 1) and Ca3Rh4Sn13 show some unusual properties similar to the Fe-pnictides, through 119Sn nuclear magnetic resonance (NMR) measurements. In (Sr1−xCax)3Ir4Sn13, the NMR linewidth increases below a temperature T* that is higher than the structural phase transition temperature Ts. The spin-lattice relaxation rate (1/T1) divided by temperature (T), 1/T1T and the Knight shift K increase with decreasing T down to T*, but start to decrease below T*, and followed by more distinct changes at Ts. In contrast, none of the anomalies is observed in Ca3Rh4Sn13 that does not undergo a structural phase transition. The precursory phenomenon above the structural phase transition resembles that occurring in Fe-pnictides. In the superconducting state of Ca3Ir4Sn13, 1/T1 decays as exp(−Δ/kBT) with a large gap Δ = 2.21kBTc, yet without a Hebel-Slichter coherence peak, which indicates strong-coupling superconductivity. Our results provide new insight into the relationship between superconductivity and the electronic-structure change associated with structural phase transition.
Development of skeletal metastases Kitazawa, S; Maeda, S
Clinical orthopaedics and related research,
03/1995, Letnik:
312, Številka:
312
Journal Article
Recenzirano
Skeletal metastases result from a series of complex steps including activation of osteoclasts and interaction between adhesion molecules on cancer cells and bone matrices. Researchers of this study ...used pathologic specimens of breast cancer cells from primary and metastatic sites obtained at surgery or autopsy to demonstrate the expression of parathyroid hormone-related protein by immunohistochemistry and beta 3 integrin by in situ hybridization to clarify the role of tumor-derived osteoclast activating factors and adhesion molecules in the development of skeletal metastases. The results of this retrospective study showed a significant difference of parathyroid hormone-related protein and beta 3 integrin expression in cases with and without skeletal metastases. These expressions were enhanced or clonally selected or both in skeletal metastatic sites. Because activation of osteoclastic bone resorption by parathyroid hormone-related protein could facilitate tumor cells to attach to the eroded bone surface through cell adhesion molecules, these 2 factors could make it easier for tumor cells to grow in bone.
Here we report on the charge-ordered structure of LiRh2O4 arising below the metal-insulator transition at 170 K. Structural studies using synchrotron x rays have revealed that the charge-ordered ...states of Rh3+ and Rh4+ with dimerization are realized in the low-temperature phase below 170 K. Although the low-temperature ground state resembles that of CuIr2S4, a charge-ordering pattern satisfying the Anderson condition is realized in LiRh2O4. Based on structural information such as the short-range order of dimers appearing above the transition temperature and the weakening of the correlation between rhodium one-dimensional chains appearing in the crystal structure, we argue that the Coulomb interaction plays an important role in determining the charge-ordering patterns.
Homologous regions (hrs) hr1, hr2-left, hr2-right, hr3, hr4-left, hr4-right, and hr5) similar to those found in the Autographa californica nuclear polyhedrosis virus (AcNPV) genome were found in the ...Bombyx mori NPV (BmNPV) genome. The BmNPV hrs contained two to eight repeats of a homologous nucleotide sequence which were on average about 75 bp long. All of these homologous sequence repeats contained a 26-bp-long palindrome motif with an EcoRI or EcoRI-like site at its core. The consensus sequence of the BmNPV hrs showed 95% conservation with respect to those found in AcNPV. Nucleotide sequence analysis indicated that hr2-left and hr2-right of BmNPV evolved from an ancestor similar to hr2 of AcNPV by inversion, cleavage, and ligation. The polarities of the BmNPV and AcNPV hrs were conserved except for that of hr4-left. Within hr4-right of BmNPV, four repeats of a previously undescribed palindrome motif were found. Bmhr5D, a BmNPV mutant which lacked hr5, replicated at a rate similar to that of wild-type BmNPV in BmN cells and silkworm larvae, indicating that hr5 was not essential for viral replication. After ten passages of Bmhr5D in BmN cells, no detectable changes in its genome were observed by restriction endonuclease analysis. The evolution and divergence of the BmNPV genome are also discussed
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