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121.
In this study, we investigated the surface characteristics of the TiN/ZrN-coated nanotubular structure on Ti-35Ta-xHf ternary alloys for bio-implant applications. These ternary alloys contained from 3 wt.% to 15 wt.% Hf contents and were manufactured in an arc-melting furnace. The Ti-35Ta-xHf alloys were heat treated in Ar atmosphere at 1000 °C for 24 h, followed by water quenching. Formation of the nanotubular structure was achieved by an electrochemical method in 1 M H3PO4 electrolytes containing 0.8 wt.% NaF. The TiN coating and ZrN coating were subsequently prepared by DC-sputtering on the nanotubular surface. Microstructures and nanotubular morphology of the alloys were examined by FE-SEM, EDX and XRD. The microstructure showed a duplex (α′′ + β) phase structure. Traces of martensite disappeared with increasing Hf content, and the Ti-35Nb-15Hf alloy had an entirely equiaxed structure of β phase. This research has shown that highly ordered, high aspect ratio, and nanotubular morphology surface oxide layers can be formed on the ternary titanium alloys by anodization. The TiN and ZrN coatings formed on the nanotubular surfaces were uniform and stable. The top of the nanotube layers was uniformly covered with the ZrN film compared to the TiN film when the Ti-35Ta-xHf alloys had high Hf content. 相似文献
122.
Boo Rim Choe Hyungwoon Koo Michael Stessin 《Integral Equations and Operator Theory》2009,63(4):501-520
We obtain new characterizations of Carleson measures via uniform boundedness of BMO norms of certain mass functions associated
with the given measure in a natural way.
This research was performed during M. Stessin’s visit to Korea University. He thanks the Mathematics Department of Korea University
and the “Brain Pool” program for their hospitality and support. The first two authors were supported by the Korea Research
Foundation Grant funded by the Korean Government (KRF-2008-314-C00012). 相似文献
123.
In this paper, we study a Green’s functions G
E
, G
S
for an elasto-static equations and Stokes equations in a three-dimensional bounded Lipschitz domain Ω. We prove that there
is a positive constant c > 0 depending on the Lipschitz constant such that for all . Furthermore, we show that there is a positive constant η ∈ (0,1) depending on the Lipschitz constant such that for all .
The second author is partially supported by Korea Research Foundation Grant KRF C-00005. 相似文献
124.
Polarization switching dynamics governed by the thermodynamic nucleation process in ultrathin ferroelectric films 总被引:1,自引:0,他引:1
In most ferroelectrics, the domain nucleation barrier (U*) is thermally insurmountable; this is called "Landauer's paradox." However, we showed that, in ultrathin films, the large depolarization fields could lower U* to a level comparable to thermal energy (k(B)T), resulting in power-law decay of polarization. We empirically found a universal relation between the power-law decay exponent and U*/k(B)T. This relation will provide a practical but fundamental limit for capacitor-type ferroelectric devices, analogous to the superparamagnetic limit for magnetic memory devices. 相似文献
125.
J.L. Kim J.I. Lee A.S. Pradhan I. Chang B.H. Kim K.S. Chung H.S. Choe 《Radiation measurements》2010,45(3-6):583-585
Several thermal treatments in the temperature range from 270 °C to 320 °C (each of 10 min) were tested as a final preparation procedure of LiF:Mg,Cu,Si to improve the protocol of TL readout with less residual signal for the LiF:Mg,Cu,Si TLD. This high sensitivity LiF:Mg,Cu,Si TLD exhibited thermal stability much better than that of the well known LiF:Mg,Cu,P. For LiF:Mg,Cu,Si, a readout temperature up to 300 °C did not affect the TL sensitivity and glow curve structure for 12 cycles of exposure and readout following an initial thermal treatment at 295 °C for 10 min. The residual TL signal also remained negligible. 相似文献
126.
Myong-Song Ryang Chol-Jun Kang Hyon-Chol Choe Nam-Hyok Kim 《International journal of quantum chemistry》2019,119(24):e26022
The best quantity correlated to the electronic energy band gap is found for alkali and alkaline-earth metal oxides and halides with face centered cubic (fcc) structure based on density functional theory and Bader's atom-in-molecule theory. Previous studies show the correlation of the band gap to the ground state electron density at the bond critical point (BCP). Whereas, in quantum mechanics, the gap between the energy levels of one dimensional square well potential is inversely proportional to the square of the width of the well which is the metal–nonmetal chemical bond length in our case. These motivate the proposition of a new quantity Q, the ratio of the density at the BCP to the square of the bond length. Our study reveals that, for the aforementioned materials, the band gap has a strong correlation to Q when they are multiplied by the density at the BCP. 相似文献
127.
Abstract In this review, we classify 1D, 2D, and 3D structural motifs found in porphyrinic coordination polymers assembled from 5,10,15,20-tetrapyridylporphyrin
(TPyP) and its derivatives. The classifications are based on dimensionality, metal-to-porphyrin linkage, porphyrin type, and
metal-to-porphyrin ratio. 1D porphyrin polymers often share the same connectivity (or structural motifs) with analogous 2D
and 3D polymers. We identify interrelationships among 1D, 2D, and 3D coordination polymers and examine the connectivity of
such interrelated structures. We also discuss the broad similarities and differences of the synthetic methods of all structures
presented here.
Graphical Abstract We classify 1D, 2D, and 3D structural motifs found in porphyrinic coordination polymers assembled from 5,10,15,20-tetrapyridylporphyrin
(TPyP) and its derivatives. The classifications are based on dimensionality, metal-to-porphyrin linkage, porphyrin type, and
metal-to-porphyrin ratio. We identify interrelationships among 1D, 2D, and 3D coordination polymers and examine the connectivity
of such interrelated structures.
相似文献
128.
129.
A powerful argon ion laser was used to excite gaseous chlorine molecules resonantly from the X1Σ ground electronic state to the excited electronic state. Three progressions of P, R doublets which correspond to the excitation from J=37, 13 and 39 of v=0 of the X1Σ state to v′=22, J′=38; v′=18, J′=12 and v′=16, J′=38 of the state, respectively, and then decaying to various vibrational levels of the X1Σ state were observed. Of those, only the excitation from v=0, J=38 to v′=22, J′=38 transition has been reported before. Due to the extremely small transition probabilities, the spectral lines are much weaker than those of iodine and bromine. Their positions and their relative intensities were analyzed and compared with the result calculated from the known molecular constants and with the known Franck-Condon factors. Our data are consistent with the calculated results within the range of experimental error. 相似文献
130.
Hong SJ Yang HI Yoo MC In CS Yim SV Jin SY Choe BK Chung JH 《Experimental & molecular medicine》2003,35(3):189-195
Angiotensin converting enzyme (ACE) plays an important role in the physiology of vasculature, blood pressure and inflammation. ACE gene, known to have insertion/deletion (I/D) polymorphism, has been widely investigated in its relation with cardiovascular and neurodegenerative diseases and longevity. ACE gene polymorphism in an inflammation associated osteoarthritis (OA) patients is not known. Here we have investigated ACE gene polymorphism in 142 Korean primary knee OA patients and 135 healthy volunteers to establish any clinical correlates between ACE polymorphism and knee osteoarthritis. Clinical parameters such as disease onset age, Kellgren-Lawrence grade and Lequesne's functional index provided additional analysis of the relationship of ACE polymorphism and clinical features of OA. Early onset OA showed significantly higher allele frequency and carriage rate of I than late onset OA. Radiographically severe and functionally poor OA showed higher carriage rate of I allele than radiographically mild and functionally good OA, respectively. This study first reports ACE gene polymorphism to be a risk factor for early onset, severe form primary knee OA. 相似文献