http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ti-based Quasicrystal Layers Produced by Plasma Thermal Spraying
Takasaki Akito,Uematsu Susumu,Kelton K.F. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
[ ] powders were thermally sprayed onto mild steel substrates in air and under a reduced pressure of argon. Several oxides were formed after thermally-spraying the mechanically-alloyed powders in air. After spraying in a reduced pressure of argon, the coating layers obtained from the gently mixed powders consisted of the elemental metals, but an amorphous phase primarily appeared in the thermally-sprayed mechanically-alloyed powders, which transformed into the icosahedral quasicrystal phase and a minor crystal phase after annealing at 828 K. The Vickers hardness and the contact angle with pure water for the quasicrystal layers were about 7 GPa and respectively.
Kim Jae Yong,Gibbons, P . C .,Kelton, K . F . 대한금속재료학회(대한금속학회) 1999 METALS AND MATERIALS International Vol.5 No.6
To evaluate their technological usefulness and to probe the local structure of the quasicrystal, p-c-T curves were measured for as-quenched Ti_(45)Zr_(38)Ni_(17) and Ti_(45)Zr_(30)Ni_(25) quasicrystal ribbons at 350℃ with a computer-controlled apparatus. For both quasicrystals, the p-c-T curves do not exhibit a clear pressure plateau. Instead, the equilibrium vapor pressure remains low ($lt; 5 torn) below H/M ◎1; it increases sharply for increasing H/M. Such p-c-T curves may reflect structural features of the quasicrystal. Due to the formation of the crystal hydride phase during the p-c-T measurements, however, the site energy distribution in the quasicrystals could not be obtained. Instead, qualitative conclusions are presented. For Ti_(45)Zr_(38)Ni_(17) quasicrystals, estimates of the site energy distribution for hydrogen suggest a prominent site located between -0.2 eV and -0.15 eV with a possible broad, weakly binding second peak at higher energy. The site energy locations for hydrogen for Ti_(45)Zr_(30)Ni_(25) quasicrystals are similar. The Ti_(45)Zr_(38)Ni_(17) quasicrystals desorb most of the absorbed hydrogen at 650℃ in one hour by continuous pumping without phase transformation, and do not become powder after three cycles.
Lee, G.W.,Gangopadhyay, A.K.,Kelton, K.F. Elsevier Science 2011 ACTA MATERIALIA Vol.59 No.12
A detailed phase diagram study of Ti-Zr-Ni alloys has been conducted using conventional X-ray scattering, microstructural and thermal annealing, and levitation techniques, to improve on the existing phase diagram. Various phases, such as simple crystalline, approximant, icosahedral quasicrystalline, and complex polytetrahedral phases, have been identified. A eutectic composition has been found near 21at.% Ni for nearly equal Ti and Zr concentrations. From containerless processing studies, using electrostatic levitation, the phase boundary of the icosahedral quasicrystal (i-phase) is placed between 29 and 45at.% Ti with 21at.% Ni. A first-time estimate of the critical cooling rate for the formation of the i-phase directly from the liquid in alloys with 21at.% Ni is less than 100<SUP>o</SUP>Cs<SUP>-1</SUP>, which is much smaller than for most of the known metastable quasicrystals.
Interfacial free energy and medium range order: Proof of an inverse of Frank's hypothesis
Lee, Geun Woo,Cho, Yong Chan,Lee, Byeongchan,Kelton, Kenneth F. American Physical Society 2017 Physical Review B Vol.95 No.5
<P>We study the relation of crystal-liquid interfacial free energy and medium range order in the quasicrystal-forming Ti37Zr42Ni21 liquid from undercooling experiment and ab initio molecular dynamics (MD) simulation. Adding a small amount of Ag to the liquid significantly reduces the degree of undercooling, which is suggestive of small interfacial free energy, and thus very similar atomic configuration between the liquid and the icosahedral quasicrystal phases. Using ab initioMDstudy, we find that Ag atoms predominantly form a bond with Zr atoms in the short range and, further, Ag-Zr pairs are extended in the liquid, as amedium range orderwhich is identical to the global structural feature reported recently [Liu et al., Phys. Rev. Lett. 105, 155501 (2010)]. This result may expect extremely small undercooling if the icosahedral medium range order exists in a liquid forming an icosahedral quasicrystal, which implies the ambiguity of clear distinction of heterogeneous and homogeneous nucleation.</P>
Ashok Agarwal,Neel Parekh,Manesh Kumar Panner Selvam,Ralf Henkel,Rupin Shah,Sheryl T. Homa,Ranjith Ramasamy,Edmund Ko,Kelton Tremellen,Sandro Esteves,Ahmad Majzoub,Juan G. Alvarez,David K. Gardner,Cha 대한남성과학회 2019 The World Journal of Men's Health Vol.37 No.3
Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and DNA, which may impair the sperm’s potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants (antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis, future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause.