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"Taka"
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Gathering for tea in modern Japan : class, culture and consumption in the Meiji period
\"By examining chanoyu - the custom of consuming matcha tea - in the Meiji period, Gathering for Tea in Modern Japan investigates the interactions between intellectual and cultural legacies of the Tokugawa period and the incoming influences of Western ideas, material cultures and institutions. It explores the construction of Japan's modern cultural identity, highlighting the development of new social classes, and the transformation of cultural practices and production-consumption networks of the modern era. Taka Oshikri uses a wealth of Japanese source material - including diaries, newspaper, journal articles, maps, exhibition catalogues and official records - to explore the intricate relationships between the practice and practitioners of different social groups such as the old aristocracy, the emerging industrial elite, the local elite and government officials. She argues that the fabrication of a cultural identity during modernisation was influenced by various interest groups, such as the private commercial sector and foreign ambassadors. Although much is written on the practice of chanoyu in the pre-Tokugawa period and present-day Japan, there are few historical studies focusing on the late 19th and early 20th centuries. Gathering for Tea in Modern Japan thus makes a significant contribution to its field, and will be of great value to students and scholars of modern Japanese social and cultural history.\"--Page 4 of cover.
Book
Controlled transformation of skyrmions and antiskyrmions in a non-centrosymmetric magnet
Control of topological spin textures in magnetic systems may enable future spintronic applications. Magnetic field pulses can switch the vortex polarity1 or the winding number of magnetic bubbles2. Thermal energy can reverse the helicity of skyrmions3 and induce the transformation between meron and skyrmion by modifying the in-plane anisotropy4,5. Among the various topological spin textures, skyrmions6,7 and antiskyrmions8–10 are nanometric spin-whirling structures carrying integer topological charges (N) of −1 and +1 (refs. 7,11,12), respectively, and can be observed in real space8,13. They exhibit different dynamical properties under current flow14–18, for example, opposite signs for the topological Hall effect. Here we observe, in real space, transformations among antiskyrmions, non-topological (NT) bubbles and skyrmions (with N of +1, 0 and −1, respectively) and their lattices in a non-centrosymmetric Heusler magnet, Mn1.4Pt0.9Pd0.1Sn, with D2d symmetry. Lorentz transmission electron microscopy images under out-of-plane magnetic fields show a square lattice of square-shaped antiskyrmions near the Curie temperature and a triangular lattice of elliptically deformed skyrmions with opposite helicities at lower temperatures. The clockwise and counter-clockwise helicities of the skyrmions originate from Dzyaloshinskii–Moriya interactions with opposite signs along the [100] and [010] directions, respectively. A variation of the in-plane magnetic field induces a topological transformation from antiskyrmions to NT-bubbles and to skyrmions, which is accompanied by a change of the lattice geometry. We also demonstrate control of the helicity of skyrmions by variations of the in-plane magnetic field. These results showcase the control of the topological nature of spin configurations in complex magnetic systems.Skyrmions and antiskyrmions are nanometric spin whirls with opposite topological charges. In the Heusler magnet Mn1.4Pt0.9Pd0.1Sn, modulations of the orientation and strength of an in-plane magnetic field induces the transformation from antiskyrmions to non-topological bubbles and skyrmions.
Journal Article
Extracellular vesicles as trans‐genomic agents: Emerging roles in disease and evolution
The composition of genetic material in extracellular vesicles (EV) has sparked interest particularly in the potential for horizontal gene transfer by EV. Although the RNA content of EV has been studied extensively, few reports have examined the DNA content of EV. It is still unclear how DNA is packaged inside EV, and whether they are functional in recipient cells. In this review, we describe the biological significance of genetic material in EV and their possible impacts in recipient cells, with focus on DNA from cancer cell‐derived EV and the potential roles they may play in the cancer microenvironment. Another important feature of the genetic content of EV is the presence of retrotransposon elements. In this review, we discuss the possibility of an EV‐mediated mechanism for the dispersal of retrotransposon elements, and their potential involvement in the development of genetically influenced diseases. In addition to this, we discuss the potential involvement of EV in the transfer of genetic material across species, and their possible impacts in modulating genome evolution. In this review paper, we describe the biological significance of genetic material in extracellular vesicles (EVs), with particular focus on the EV‐mediated transfer of DNA and retrotransposon elements. We describe the functional impacts of horizontal gene transfer by EVs in the development of genetically influenced diseases such as cancer and neurodegenerative diseases. We also discuss the potential involvement of EVs in the transfer of retrotransposon elements across species, and their potential impacts in genome modulation in evolution.
Journal Article
Imaging the coupling between itinerant electrons and localised moments in the centrosymmetric skyrmion magnet GdRu2Si2
Magnetic skyrmions were thought to be stabilised only in inversion-symmetry breaking structures, but skyrmion lattices were recently discovered in inversion symmetric Gd-based compounds, spurring questions of the stabilisation mechanism. A natural consequence of a recent theoretical proposal, a coupling between itinerant electrons and localised magnetic moments, is that the skyrmions are amenable to detection using even non-magnetic probes such as spectroscopic-imaging scanning tunnelling microscopy (SI-STM). Here SI-STM observations of GdRu
2
Si
2
reveal patterns in the local density of states that indeed vary with the underlying magnetic structures. These patterns are qualitatively reproduced by model calculations which assume exchange coupling between itinerant electrons and localised moments. These findings provide a clue to understand the skyrmion formation mechanism in GdRu
2
Si
2
.
GdRu
2
Si
2
can host magnetic skyrmions, however, it does not have inversion symmetry breaking, a feature usually assumed necessary for skyrmion formation. Using scanning tunnelling microscopy, the authors visualise the double-
Q
structure in the itinerant electrons that mediate the skyrmion formation.
Journal Article
Square and rhombic lattices of magnetic skyrmions in a centrosymmetric binary compound
Magnetic skyrmions are topologically stable swirling spin textures with particle-like character, and have been intensively studied as a candidate of high-density information bit. While magnetic skyrmions were originally discovered in noncentrosymmetric systems with Dzyaloshinskii-Moriya interaction, recently a nanometric skyrmion lattice has also been reported for centrosymmetric rare-earth compounds, such as Gd
2
PdSi
3
and GdRu
2
Si
2
. For the latter systems, a distinct skyrmion formation mechanism mediated by itinerant electrons has been proposed, and the search of a simpler model system allowing for a better understanding of their intricate magnetic phase diagram is highly demanded. Here, we report the discovery of square and rhombic lattices of nanometric skyrmions in a centrosymmetric binary compound EuAl
4
, by performing small-angle neutron and resonant elastic X-ray scattering experiments. Unlike previously reported centrosymmetric skyrmion-hosting materials, EuAl
4
shows multiple-step reorientation of the fundamental magnetic modulation vector as a function of magnetic field, probably reflecting a delicate balance of associated itinerant-electron-mediated interactions. The present results demonstrate that a variety of distinctive skyrmion orders can be derived even in a simple centrosymmetric binary compound, which highlights rare-earth intermetallic systems as a promising platform to realize/control the competition of multiple topological magnetic phases in a single material.
Typically, skyrmions appear in magnet systems which are non-centrosymmetric. Here, using neutron and X-ray scattering, Takagi et al show the emergence of a skyrmion phase in the centrosymmetric material EuAl
4
. This expands the range of materials potential hosting skyrmions.
Journal Article
Neutralization of the SARS-CoV-2 Mu Variant by Convalescent and Vaccine Serum
The mu variant of SARS-CoV-2 was 10.6 times as resistant to neutralization by serum samples obtained from persons who had recovered from Covid-19 as the B.1 lineage virus and 9.1 times as resistant to neutralization by serum samples from persons who had received the BNT162b2 vaccine.
Journal Article
Synthesis, Characterization and Antimicrobial Activity of Zinc Oxide Nanoparticles against Selected Waterborne Bacterial and Yeast Pathogens
The disinfection of wastewater using nanoparticles (NPs) has become a focal area of research in water treatment. In this study, zinc oxide (ZnO) NPs were synthesized using the microwave heating crystallization technique and characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Qualitative well diffusion and quantitative minimum inhibitory concentration (MIC) tests were conducted to determine the antimicrobial activity of ZnO NPs against selected waterborne pathogenic microbes. FTIR spectral studies confirmed that the binding of urea with Zn occurs through Zn–O stretching. XRD confirmed the crystallized identity in a hexagonal ZnO wurtzite-type structure. The formation of zones of inhibition and low MIC values in the antimicrobial analysis were indicative of the effective antimicrobial activity of zinc oxide nanoparticles against the test microorganisms. The application of metallic nanoparticles in water treatment could curb the spread of waterborne microbial diseases.
Journal Article
Discovery of lipid profiles in plasma‐derived extracellular vesicles as biomarkers for breast cancer diagnosis
Lipids are a major component of extracellular vesicles; however, their significance in tumorigenesis and progression has not been well elucidated. As we previously found that lipid profiles drastically changed in breast tumors upon progression, we hypothesized that lipid profiles of plasma‐derived extracellular vesicles could be utilized as breast cancer biomarkers. Here, we adopted modified sucrose cushion ultracentrifugation to isolate plasma‐derived extracellular vesicles from breast cancer ( n = 105), benign ( n = 11), and healthy individuals ( n = 43) in two independent cohorts ( n = 126 and n = 33) and conducted targeted lipidomic analysis. We established a breast cancer diagnostic model comprising three lipids that showed favorable performance with the area under the receiver operating characteristic curve of 0.759, 0.743, and 0.804 in the training, internal validation, and external test sets, respectively. Moreover, we identified several lipids that could effectively discriminate breast cancer progression and subtypes: phosphatidylethanolamines and phosphatidylserines were relatively higher in Stage III, whereas phosphatidylcholines and sphingomyelins were higher in Stage IV; phosphatidylcholines and ceramides were correspondingly concentrated in HER2‐positive patients, while lysophosphatidylcholines and polyunsaturated triglycerides were concentrated in the triple‐negative breast cancer subtype. Lipid profiling of plasma‐derived extracellular vesicles is a non‐invasive and promising approach for diagnosing, staging, and subtyping breast cancer.
Journal Article
Nanometric square skyrmion lattice in a centrosymmetric tetragonal magnet
Magnetic skyrmions are topologically stable spin swirls with a particle-like character and are potentially suitable for the design of high-density information bits. Although most known skyrmion systems arise in non-centrosymmetric systems with a Dzyaloshinskii–Moriya interaction, centrosymmetric magnets with a triangular lattice can also give rise to skyrmion formation, with a geometrically frustrated lattice being considered essential in this case. Until now, it remains an open question if skyrmions can also exist in the absence of both geometrically frustrated lattice and inversion symmetry breaking. Here we discover a square skyrmion lattice state with 1.9 nm diameter skyrmions in the centrosymmetric tetragonal magnet GdRu2Si2 without a geometrically frustrated lattice by means of resonant X-ray scattering and Lorentz transmission electron microscopy experiments. A plausible origin of the observed skyrmion formation is four-spin interactions mediated by itinerant electrons in the presence of easy-axis anisotropy. Our results suggest that rare-earth intermetallics with highly symmetric crystal lattices may ubiquitously host nanometric skyrmions of exotic origins.Experimental realizations of magnetic skyrmions, particle-like spin swirls with topological protection, so far have required inversion symmetry breaking or a geometrically frustrated lattice. In centrosymmetric GdRu2Si2, in which a geometrically frustrated lattice is absent, a skyrmion lattice phase emerges, which is probably stabilized by four-spin interactions mediated by itinerant electrons in the presence of easy-axis anisotropy.
Journal Article
Skyrmion phase and competing magnetic orders on a breathing kagomé lattice
Magnetic skyrmion textures are realized mainly in non-centrosymmetric, e.g. chiral or polar, magnets. Extending the field to centrosymmetric bulk materials is a rewarding challenge, where the released helicity/vorticity degree of freedom and higher skyrmion density result in intriguing new properties and enhanced functionality. We report here on the experimental observation of a skyrmion lattice (SkL) phase with large topological Hall effect and an incommensurate helical pitch as small as 2.8 nm in metallic Gd
3
Ru
4
Al
12
, which materializes a breathing kagomé lattice of Gadolinium moments. The magnetic structure of several ordered phases, including the SkL, is determined by resonant x-ray diffraction as well as small angle neutron scattering. The SkL and helical phases are also observed directly using Lorentz-transmission electron microscopy. Among several competing phases, the SkL is promoted over a low-temperature transverse conical state by thermal fluctuations in an intermediate range of magnetic fields.
Understanding and controlling the skyrmion lattice (SkL) phase facilitates its versatile applications. Here the direct observation of a SkL phase with large topological Hall effect in centrosymmetric Gd
3
Ru
4
Al
12
is reported, which is stabilized by thermal fluctuations and magnetic field without Dzyaloshinskii-Moriya interactions.
Journal Article