Summary
We developed a new tool to assess the severity of osteoporotic vertebral fracture using radiographs of the spine. Our technique can be used in patient care by helping to stratify patients ...with osteoporotic vertebral fractures into appropriate treatment pathways. It can also be used for research purposes.
Purpose
The aim of our study was to propose a semi-quantitative (SQ) grading scheme for osteoporotic vertebral fracture (OVF) on anteroposterior (AP) radiographs.
Methods
On AP radiographs, the vertebrae are divided into right and left halves, which are graded (A) vertical rectangle, (B) square, (C) traverse rectangle, and (D) trapezoid; whole vertebrae are graded (E) transverse band or (F) bow-tie. Type A and B were compared with normal and Genant SQ grade 1 OVF, Type C and D with grade 2 OVF, and Type E and F with grade 3 OVF. Spine AP radiographs and lateral radiographs of 50 females were assessed by AP radiographs SQ grading. After training, an experienced board-certified radiologist and a radiology trainee assessed the 50 AP radiographs.
Results
The height-to-width ratio of the half vertebrae varied 1.32–1.48. On lateral radiographs, 84 vertebrae of the 50 patients had OVFs (38 grade 1, 24 grade 2, and 22 grade 3). On AP radiographs, the radiologist correctly assigned 84.2%, 91.7%, and 77.2% and the trainee correctly assigned 68.4%, 79.2%, and 81.8% of grade 1, 2, and 3 OVFs, respectively. Compared with lateral radiographs, the radiologist had a weighted Kappa of 0.944 including normal vertebrae and 0.883 not including normal vertebrae, while the corresponding Kappa values for the trainee were 0.891 and 0.830, respectively.
Conclusion
We propose a new semi-quantitative grading system for vertebral fracture severity assessment on AP spine radiographs.
The intermediate product Li2S2 plays a pivotal role in the charge/discharge process of lithium–sulfur batteries. However, the structural configuration and relevant properties of Li2S2 are unclear. In ...this work, by using ab initio calculations, we present results of novel phases, average open circuit voltages (V ocs), and electronic properties of the stable Li2S2. Two new Li2S2 phases are predicted: orthorhombic (Cmca) and orthorhombic (Immm) structures. The calculated V ocs of hexagonal (P63/mmc), orthorhombic (Cmca), and orthorhombic (Immm) are 3.91, 3.95, and 3.88 V, respectively. In particular, the calculated band gap of the Immm structure is about 0.225 eV, which is smaller than that of Li2S. The narrow band gap of Li2S2 derives from the electronic lump between the Li s state and S 3p state for the orthorhombic structure. Therefore, the electronic properties of Li2S2 are markedly influenced by the structural configuration.
The local atomic structures of amorphous Ge-Sb-Te phase-change materials have yet to be clarified and the rapid crystal-amorphous phase change resulting in distinct optical contrast is not well ...understood. We report the direct observation of local atomic structures in amorphous Ge_{2}Sb_{2}Te_{5} using "local" reverse Monte Carlo modeling dedicated to an angstrom-beam electron diffraction analysis. The results corroborated the existence of local structures with rocksalt crystal-like topology that were greatly distorted compared to the crystal symmetry. This distortion resulted in the breaking of ideal octahedral atomic environments, thereby forming local disordered structures that basically satisfied the overall amorphous structure factor. The crystal-like distorted octahedral structures could be the main building blocks in the formation of the overall amorphous structure of Ge-Sb-Te.
Abstract
Supported atomic metal sites have discrete molecular orbitals. Precise control over the energies of these sites is key to achieving novel reaction pathways with superior selectivity. Here, ...we achieve selective oxygen (O
2
) activation by utilising a framework of cerium (Ce) cations to reduce the energy of 3
d
orbitals of isolated copper (Cu) sites. Operando X-ray absorption spectroscopy, electron paramagnetic resonance and density-functional theory simulations are used to demonstrate that a Cu(I)O
2
3−
site selectively adsorbs molecular O
2
, forming a rarely reported electrophilic η
2
-O
2
species at 298 K. Assisted by neighbouring Ce(III) cations, η
2
-O
2
is finally reduced to two O
2−
, that create two Cu–O–Ce oxo-bridges at 453 K. The isolated Cu(I)/(II) sites are ten times more active in CO oxidation than CuO clusters, showing a turnover frequency of 0.028 ± 0.003 s
−1
at 373 K and 0.01 bar
P
CO
. The unique electronic structure of Cu(I)O
2
3−
site suggests its potential in selective oxidation.
In addition to oxidation resistance, the improvement of hydrogen embrittlement is also a big challenge for the noble metal thermal barrier coating. Unfortunately, the hydrogenation mechanism of noble ...metal thermal barrier coating is unknown. In this study, we apply the first-principles calculations to investigate the hydrogenation mechanism of PtAl and IrAl thermal barrier coatings. In particular, we further study the influence of hydrogen on the mechanical and thermodynamic properties of PtAl and IrAl coatings. Two hydrogen occupied sites: H(1) and H(2) models are considered. In either case, hydrogen is stable in PtAl and IrAl coatings. It is found that hydrogen prefers to occupy the H(2) model, while the hydrogen in this model is surrounded by the two Pt atoms and four Al atoms. PtAl-H(1), IrAl-H(1) and IrAl-H(2) models not only weaken the volume deformation resistance, shear deformation resistance and elastic stiffness, but also reduce the Debye temperature of PtAl and IrAl coatings. However, the PtAl-H(2) model improves the shear deformation resistance and elastic stiffness, in addition to the improvement of Debye temperature of PtAl thermal barrier coating. The low mechanical properties are that the hydrogen weakens the localized hybridization between the noble metal and Al atom.
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•Hydrogenation mechanism of PtAl and IrAl coatings is studied.•We find that hydrogen is easy to absorb in PtAl and IrAl coatings.•H(2) model is more thermodynamically stable than the H(1) model.•H(1) model weakens the bulk, shear and Young's modulus of PtAl and IrAl.•Hydrogen enhances the Debye temperature of PtAl coating.
Despite the fact that phase-change materials are widely used for data storage, no consensus exists on the unique mechanism of their ultrafast phase change and its accompanied large and rapid optical ...change. By using the pump-probe observation method combining a femtosecond optical laser and an x-ray free-electron laser, we substantiate experimentally that, in both GeTe and Ge_{2}Sb_{2}Te_{5} crystals, rattling motion of mainly Ge atoms takes place with keeping the off-center position just after femtosecond-optical-laser irradiation, which eventually leads to a higher symmetry or disordered state. This very initial rattling motion in the undistorted lattice can be related to instantaneous optical change due to the loss of resonant bonding that characterizes GeTe-based phase change materials. Based on the amorphous structure derived by first-principles molecular dynamics simulation, we infer a plausible ultrafast amorphization mechanism via nonmelting.
To identify genes associated with tumor metastasis in hepatocellular carcinoma (HCC), gene expression profiles between a pair of primary HCC (H2-P) and their matched metastatic HCC (H2-M) were ...compared. Overexpression of clusterin (CLU) was found in H2-M cells. To determine the roles CLU played in HCC metastasis, CLU was transfected into H2-P cells. Overexpression of CLU in H2-P cells increased cell migration by twofold in vitro and formation of metastatic tumor nodules in liver by eightfold in vivo. To evaluate the correlation of CLU expression with HCC metastasis, the expression levels of CLU in HCCs were investigated using a tissue microarray (TMA) containing 104 pairs of primary HCCs and their matched metastases. The frequency of CLU overexpression increased significantly in metastatic HCCs (59.1%) compared with that in primary tumors (32.6%, P<0.001). To gain additional insight into the function of CLU, the expression profile of H2P-CLU was compared with vector-transfected H2-P cells by cDNA microarray. A total of 35 upregulated and 14 downregulated genes were detected in H2P-CLU. One of the upregulated genes known as YKL-40, which is implicated in matrix-remodeling and metastasis, was further studied using TMA. A significant correlation (P<0.001) between the expression levels of YKL-40 and CLU was observed, implying that the CLU-YKL-40 pathway may play an important role in HCC metastasis.
Ti-6Al-4V has been used as a surgical implant material for a long time because of its combination of strength, corrosion resistance and biocompatibility. However, there remains much that is not ...understood about how the surface reacts with the environment under tribocorrosion conditions. In particular, the conditions under which tribofilms form and their role on friction and wear are not clear. To evaluate the complicated nature of the dynamic surface microstructural changes on the wear track, high resolution transmission electron microscopy (TEM), scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) have been used to characterise the structure and chemical composition of the tribofilm. Detailed analysis of the formation and structure of the tribofilm and the metal surface deformation behaviour were studied as a function of applied potential and the role of proteins in the lubricant. For the first time, graphitic and onion-like carbon structures from wear debris were found in the testing solution. The presence of carbon nanostructures in the tribocorrosion process and the formation of the tribofilm leads to an improved tribocorrosion behaviour of the system, in particular a reduction in wear and friction. A detailed, quantitative, analysis of surface deformation was undertaken, in particular, the geometrically necessary dislocation (GND) density was quantified using precession electron diffraction (PET). A clear correlation between applied potential, tribofilm formation and the surface strain was established.
The formation of tribofilm and microstructure modification of the Ti-6Al-4V surface during tribocorrosion in a physiological environment is not fully understood. In particular, the correlation between microstructural changes and electrochemical conditions is not clear. This study presents a detailed investigation of the structure and chemical composition of tribofilms at the nanoscale during tribocorrosion tests in simulated body fluid and gives a detailed and quantitative description of the evolved surface structure. A clear correlation between applied potential, tribofilm formation and the surface strain was established. Moreover, particular attention is paid to the wear debris particles captured from the lubricating solution, including nanocarbon onion structures. The implications for tribocorrosion of the alloy in its performance as an implant are discussed.
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The occupation mechanism and influence of B doping on the electronic and mechanical properties of RuAl
2
semiconducting compound have been investigated using first-principles calculations. Four ...possible B doping sites are considered. The results show that B-doped RuAl
2
is thermodynamically stable. In particular, B element prefers to occupy B(4) site in comparison with other sites. Importantly, B doping improves the electronic properties of RuAl
2
by shifting the Al 3
p
and Ru 4
d
states from the Fermi level (
E
F
) to the valence band. Although B doping weakens the resistance to volume and shear deformation as well as the elastic stiffness of RuAl
2
, it improves the ductility due to the formation of Ru-B and Al-B bonds. Therefore, it can be concluded that B is a favorable doping element to improve the electronic properties and ductility of RuAl
2
semiconducting compound.
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