Abstract
Materials that possess nontrivial topology and magnetism is known to exhibit exotic quantum phenomena such as the quantum anomalous Hall effect. Here, we fabricate a novel magnetic ...topological heterostructure Mn
4
Bi
2
Te
7
/Bi
2
Te
3
where multiple magnetic layers are inserted into the topmost quintuple layer of the original topological insulator Bi
2
Te
3
. A massive Dirac cone (DC) with a gap of 40–75 meV at 16 K is observed. By tracing the temperature evolution, this gap is shown to gradually decrease with increasing temperature and a blunt transition from a massive to a massless DC occurs around 200–250 K. Structural analysis shows that the samples also contain MnBi
2
Te
4
/Bi
2
Te
3
. Magnetic measurements show that there are two distinct Mn components in the system that corresponds to the two heterostructures; MnBi
2
Te
4
/Bi
2
Te
3
is paramagnetic at 6 K while Mn
4
Bi
2
Te
7
/Bi
2
Te
3
is ferromagnetic with a negative hysteresis (critical temperature ~20 K). This novel heterostructure is potentially important for future device applications.
Many clinical features that are specific to moyamoya disease have been reported and cited in textbooks based on previous data. The purpose of this study is to investigate the present epidemiological ...features of moyamoya disease based on recently obtained regional all-inclusive data.
The authors performed an all-inclusive survey of moyamoya disease in Hokkaido, one of the major islands in Japan that has a population of 5.63 million. The epidemiological features were analysed based on the data from 267 newly registered patients with moyamoya disease in Hokkaido from 2002 to 2006. These analysed data were adjusted to the whole Japanese population at 2005.
The detection rate of the disease per year was 0.94 patients per 100,000 people, and prevalence was 10.5 patients per 100,000 people. The incidence of ischaemia concerned with the disease was 0.53 patients per 100,000 people-years and haemorrhage was 0.2 patients per 100,000 people-years. The ratio of female to male patients was 2.18. The ratio of patients aged 10 years and above to under 10 years of age at onset was 6.18. Two peaks for age of onset were seen: the highest was observed between 45 and 49 years, and the second between 5 and 9 years. Asymptomatic patients comprised 17.8% of the total number of patients.
The epidemiological features of moyamoya disease determined by this survey varied considerably from previous data. The detection rate and prevalence of the disease were higher than those reported previously. The highest peak of onset age was older than those reported previously. In addition, it was revealed that asymptomatic moyamoya patients are not always rare in Japan.
This review presents the recent progress in computational materials design, experimental realization, and control methods of spinodal nanodecomposition under three- and two-dimensional crystal-growth ...conditions in spintronic materials, such as magnetically doped semiconductors. The computational description of nanodecomposition, performed by combining first-principles calculations with kinetic Monte Carlo simulations, is discussed together with extensive electron microscopy, synchrotron radiation, scanning probe, and ion beam methods that have been employed to visualize binodal and spinodal nanodecomposition (chemical phase separation) as well as nanoprecipitation (crystallographic phase separation) in a range of semiconductor compounds with a concentration of transition metal (TM) impurities beyond the solubility limit. The role of growth conditions, codoping by shallow impurities, kinetic barriers, and surface reactions in controlling the aggregation of magnetic cations is highlighted. According to theoretical simulations and experimental results the TM-rich regions appear in the form of either nanodots (the dairiseki phase) or nanocolumns (the konbu phase) buried in the host semiconductor. Particular attention is paid to Mn-doped group III arsenides and antimonides, TM-doped group III nitrides, Mn- and Fe-doped Ge, and Cr-doped group II chalcogenides, in which ferromagnetic features persisting up to above room temperature correlate with the presence of nanodecomposition and account for the application-relevant magneto-optical and magnetotransport properties of these compounds. Finally, it is pointed out that spinodal nanodecomposition can be viewed as a new class of bottom-up approach to nanofabrication.
Plasma-sprayed LaMgAl11O19 (LaMA) coating as a novel thermal barrier coating candidate has been studied for more than a decade, but it tends to contain significant amounts of non-equilibrium ...amorphous phase due to rapid solidification. The microstructure of such as-sprayed LaMA coating was first studied in detail by a transmission electron microscope (TEM), which revealed that the coating consisted mostly of an amorphous phase but with very thin layers of crystalline (thickness ~ 100 nm) phase at the boundary of neighboring sprayed particles. A hot corrosion test was also conducted on an as-sprayed LaMA coating as well as on a fully-crystallized coating after heat treatment by a molten V2O5-Na2SO4 mixture at 1100 °C. The coatings' cross sectional observation showed that the as-sprayed coating was affected over a wider area by the corrosion reaction than the crystallized coating. To clarify the intrinsic reactivity of the amorphous and crystalline LaMA phases with the molten salt, a piece of as-sprayed coating was crushed into powder, mixed with a salt, and tested at temperatures below and above the crystallization temperature. The reacted powder was analyzed by an X-ray diffractometer (XRD) to quantify the amounts of various phases in the sample as a function of time. The results revealed that the amorphous LaMA has a remarkably higher reaction rate with the molten salt than the crystalline phase. In fact, at the testing temperature of 1100 °C, corrosion of the sprayed LaMA powder proceeded much faster than crystallization, as almost 90% of LaMA was corroded within 30 min.
•Hot corrosion behavior of plasma sprayed LaMgAl11O19 (LaMA) coating•The LaMA coating consisted of mostly amorphous phase and thin crystalline layers•The amorphous LaMA has a remarkably high reaction rate with the molten salt.
The centromere regulates proper chromosome segregation, and its dysfunction is implicated in chromosomal instability (CIN). However, relatively little is known about how centromere dysfunction occurs ...in cancer. Here, we define the consequences of phosphorylation by cyclin E1/CDK2 on a conserved Ser18 residue of centromere-associated protein CENP-A, an essential histone H3 variant that specifies centromere identity. Ser18 hyperphosphorylation in cells occurred upon loss of FBW7, a tumor suppressor whose inactivation leads to CIN. This event on CENP-A reduced its centromeric localization, increased CIN, and promoted anchorage-independent growth and xenograft tumor formation. Overall, our results revealed a pathway that cyclin E1/CDK2 activation coupled with FBW7 loss promotes CIN and tumor progression via CENP-A-mediated centromere dysfunction.
.
Summary The human masticatory system consists of a mandible which is able to move with respect to the skull at its bilateral temporomandibular joint (TMJ) through contractions of the masticatory ...muscles. Like other synovial joints, the TMJ is loaded mechanically during function. The articular surface of the mandibular condyle is covered with cartilage that is composed mainly of collagen fibers and proteoglycans. This construction results in a viscoelastic response to loading and enables the cartilage to play an important role as a stress absorber during function. To understand its mechanical functions properly, and to assess its limitations, detailed information about the viscoelastic behavior of the mandibular condylar cartilage is required. The purpose of this paper is to review the fundamental concepts of the biomechanical behavior of the mandibular condylar cartilage. This review consists of four parts. Part 1 is a brief introduction of the structure and function of the mandibular condylar cartilage. In Part 2, the biochemical composition of the mandibular condylar cartilage is summarized. Part 3 explores the biomechanical properties of the mandibular condylar cartilage. Finally, Part 4 relates this behavior to the breakdown mechanism of the mandibular condylar cartilage which is associated with the progression of osteoarthritis in the TMJ.
Members of the Rho family of small Ras-like GTPases-including RhoA,
-B, and -C, Rac1 and -2, and Cdc42-exhibit guanine nucleotide-binding
activity and function as molecular switches, cycling between ...an inactive
GDP-bound state and an active GTP-bound state. The Rho family GTPases
participate in regulation of the actin cytoskeleton and cell adhesion through
specific targets. Identification and characterization of these targets have
begun to clarify how the Rho family GTPases act to regulate cytoskeletal
structure and cell-cell and cell-substratum contacts in mammalian cells. The
Rho family GTPases are also involved in regulation of smooth muscle
contraction, cell morphology, cell motility, neurite retraction, and
cytokinesis. However, the molecular mechanisms by which the Rho family GTPases
participate in the regulation of such processes are not well established.
Among numerous works on suspension plasma sprayed thermal barrier coatings, only a few focused on the relationship between the thermal shock resistance of SPS coatings and their mechanical ...properties. In this study, several SPS yttria-stabilized zirconia coatings were deposited with various spraying parameters including plasma gas composition, stand-off distance, and suspension formulation, then they were subjected to thermal cyclic test at 1150 °C. The results showed that despite segmented/columnar microstructure most of them failed after fewer cycles than the benchmark APS coating with conventional lamellar microstructure. Changes in the mechanical properties of the coatings such as Young's modulus and toughness after exposure to elevated temperature were evaluated. Most of the SPS coatings showed unusual change of mechanical properties, i.e., significant decrease of either Young's modulus or toughness or both. It was shown that such peculiar evolution of mechanical properties cannot be explained by the tetragonal to monoclinic transformation of YSZ, but it is rather related to the formation of very fine pores smaller 1 μm after heat treatment. The evolution of mechanical properties was linked with the results obtained in the thermal cyclic test, showing that thermal cycling resistance of SPS coatings was predominantly controlled by the mechanical properties after heat exposure, for which such phenomena as sintering-induced embrittlement may give crucial influence.
•The SPS coatings showed segmented/columnar structure and good mechanical properties.•The SPS coatings generally failed prematurely in thermal shock test.•High-temperature exposure of the SPS coatings may lead to embrittlement.•The thermal shock performance depends on the change of the mechanical properties.
Thermally sprayed coatings are one of the potential ways to increase corrosion performance of Mg alloys dedicated for aircraft applications. In our research, a novel thermal spray process called Warm ...Spraying (WS) was used to deposit Ti coatings onto AZ91E magnesium alloy. WS gives us the possibility to control the temperature of the sprayed particles by changing the nitrogen flow rate (NFR) what as a result determine the porosity of WS coatings. The microstructure, porosity and oxygen content of coatings deposited under three different NFR was determined. A relation between porosity, oxygen content and NFR was revealed. The corrosion testing in 3.5% NaCl solution of as-sprayed coatings revealed their poor corrosion resistance that led to fast degradation of the substrate. The following post-treatment with epoxy-based polymer resulted in a significant improvement of the corrosion performance of Ti warm sprayed coatings.
•Titanium warm sprayed coatings for corrosion protection•Improvement of corrosion resistance with post-treatment•Over 1000 h protection of Mg based substrate provided by Ti warm sprayed coating combined with epoxy-based sealing
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