Polyethylene glycol-modified pokeweed mitogen (PWM) as a potential non-immunogenic stimulator of lymphokine-activated killer cells

Among the various plant lectins, pokeweed mitoge (PWM) is most effective in enhancing the cytotoxicity of human lymphokine-activated killer (LAK) cells. However, the use of PWM in adoptive immunotherapy has been limited due to the strong immune response against the protein of plant origin. Amino groups in PWM was modified with 2,4-bis[O-methoxypoly(ethylene glycol)]-6-chioro-s-triazine, activated PEG2, to form PEG-PWM conjugates. Its immunoreactivity towards anti-PWM antibodies was reduced by increasing the degree of modification of amino groups in PWM. PEG-PWM, in which 54% of amino groups in PWM was modified with activated PEG2, had a nearly complete reduction of immunoreactivity. Intraperitoneal administration of PEG-PWM to mice did not produce substantial levels of anti-PWM antibodies. Nevertheless, PEG-PWM retained the ability to induce the maximum levels of cytotoxicity of human LAK cells in vitro.     

Thermal and mechanical properties of tetra‐functional mesogenic type epoxy resin cured with aromatic amine

A novel tetra‐functional epoxy monomer with mesogenic groups was synthesized and characterized by ¹H‐NMR and FTIR. The synthesized epoxy monomer was cured with aromatic amine to improve the thermal property of epoxy/amine cured system. The glass transition temperature (T_g) and coefficient of thermal expansion (CTE) of the cured system were investigated by dynamic mechanical analysis and thermal mechanical analysis. The properties of the cured system were compared with the conventional bisphenol‐A type epoxy and mesogenic type epoxy system. The storage modulus of the tetra‐functional mesogenic epoxy cured systems showed the value of 0.96 GPa at 250 °C, and T_g‐less behavior was clearly observed. The cured system also showed a low CTE at temperatures above 150 °C without incorporation of inorganic components. These phenomena were achieved by suppression of the thermal motion of network chains by introduction of both mesogenic groups and branched structure to increase the cross linking density. The temperature dependency of the tensile property and thermal conductivity of the cured system was also investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46181.     

In-Plane Magnetic Field-Driven Creation and Annihilation of Magnetic Skyrmion Strings in Nanostructures

In bulk chiral crystals, 3D structures of magnetic skyrmions form topologically protected skyrmion strings (SkS) that have shown potential as magnonic nano-waveguides for information transfer. Although SkS stability is expected to be enhanced in nanostructures of skyrmion-hosting materials, experimental observation and detection of SkS in nanostructures under an applied in-plane magnetic field is difficult. Here, temperature-dependent magnetic field-driven creation and annihilation of SkS in B20 FeGe nanostructures (nanowires and nanoplates) under in-plane magnetic field (H_||) are shown and the mechanisms behind these transformations are explained. Unusual asymmetric and hysteretic magnetoresistance (MR) features are observed but previously unexplained during magnetic phase transitions within the SkS stability regime when H_|| is along the nanostructure's long edge, which increase the sensitivity of MR detection. Lorentz transmission electron microscopy of the SkS and other magnetic textures under H_|| in corroboration with the analysis of the anisotropic MR responses elucidates the field-driven creation and annihilation processes of SkS responsible for such hysteretic MR features and reveals an unexplored stability regime in nanostructures.     

Tunable Néel–Bloch Magnetic Twists in Fe3GeTe2 with van der Waals Structure

The advent of ferromagnetism in 2D van der Waals (vdW) magnets has stimulated high interest in exploring topological magnetic textures, such as skyrmions for use in future skyrmion-based spintronic devices. To engineer skyrmions in vdW magnets by transforming Bloch-type magnetic bubbles into Néel-type skyrmions, a heavy metal/vdW magnetic thin film heterostructure has been made to induce interfacial Dzyaloshinskii–Moriya interaction (DMI). However, the unambiguous identification of the magnetic textures inherent to vdW magnets, for example, whether the magnetic twists (skyrmions/domain walls) are Néel- or Bloch-type, is unclear. Here we demonstrate that the magnetic twists can be tuned between Néel and Bloch-type in the vdW magnet Fe₃GeTe₂ (FGT) with/without interfacial DMI. We use an in-plane magnetic field to align the modulation wavevector q of the magnetizations in order to distinguish the Néel- or Bloch-type magnetic twists. We observe that q is perpendicular to the in-plane field in the heterostructure (Pt/oxidized-FGT/FGT/oxidized-FGT), while q aligns at a rotated angle with respect to the field direction in the FGT thin plate thinned from bulk. We find that the aligned domain wall twists hold fan-like modulations, coinciding qualitatively with our computational results.     

Spatially resolved diffractometry with atomic-column resolution

We demonstrate spatially resolved diffractometry in which diffraction patterns are acquired at two-dimensional positions on a specimen using scanning transmission electron microscopy (STEM), resulting in four-dimensional data acquisition. A high spatial resolution of about 0.1 nm is achieved using a stabilized STEM instrument, a spherical aberration corrector and various post-acquisition data processings. We have found a few novel results in the radial and the azimuthal scattering angle dependences of atomic-column contrast in STEM images. Atomic columns are clearly observed in dark field images obtained using the excess Kikuchi band intensity even in small solid-angle detection. We also find that atomic-column contrasts in dark field images are shifted in the order of a few tens of picometers on changing the azimuthal scattering angle. This experimental result is approximately interpretable on the basis of the impact parameter in Rutherford scattering. Spatially resolved diffractometry provides fundamental knowledge related to various STEM techniques, such as annular dark field (ADF) and annular bright field (ABF) imaging, and it is expected to become an analytical platform for advanced STEM imaging.     

Rate effect on the stress-strain relations of synthetic carbon dioxide hydrate-bearing sand and dissociation tests by thermal stimulation

Methane hydrates (MHs) have been recognized as an important material for use as a new energy resource. Recently, not only MHs, but also carbon dioxide hydrates (CO₂-hydrates), have been attracting attention from the viewpoint of CO₂ storage in the form of CO₂-hydrates. It is essential, therefore, to investigate the mechanical behaviour of gas hydrate-bearing sediments in order to achieve safe MH extraction and to ensure the long-term stability of CO₂-hydrate-storaged submarine sediments. In order to gain further knowledge of CO₂-hydrate-bearing sediments, we carried out three kinds of laboratory experiments on synthetic CO₂-hydrate-bearing sand specimens: (1) undrained triaxial compression tests with a constant strain rate, (2) undrained triaxial compression tests with a step-changed strain rate, and (3) dissociation tests on CO₂-hydrate-bearing sand specimens using the thermal stimulation method.The main findings obtained from these three experiments are as follows: First, it was found that CO₂-hydrate-bearing sand shows larger strength and larger positive dilatancy than water-saturated sand without CO₂-hydrates under undrained conditions. Second, CO₂-hydrate-bearing sand clearly exhibits strain rate dependency with an increase in hydrate saturation. It is interesting to note that hydrate saturation’s dependency on strength does not appear in cases where the strain rate is quite slow. Third, a drastic increase in pore pressure and extensive tensile strain are observed simultaneously during the dissociation of CO₂-hydrates. The pore gas pressure of CO₂, produced by the hydrate dissociation, can exceed the liquefied boundary of CO₂-gas, and the increase in pore gas pressure can be limited by the liquefaction of CO₂-gas.     

Right ventricular strain and volume analyses through deep learning-based fully automatic segmentation based on radial long-axis reconstruction of short-axis cine magnetic resonance images

Magnetic Resonance Materials in Physics, Biology and Medicine - We propose a deep learning-based fully automatic right ventricle (RV) segmentation technique that targets radially reconstructed...     

Ultrawideband characteristics of fractal dipole antennas integrated on Si for ULSI wireless interconnects

Ultrawideband characteristics of Sierpinski carpet fractal antennas fabricated on silicon substrates with the resistivities of 2290, 79.6, and 10 /spl Omega//spl middot/cm were investigated. The return losses lower than -10 dB and high transmission gains of approximately -14 dB were obtained for the antennas with 10-mm distance on the Si substrate with the resistivity of 2290 /spl Omega//spl middot/cm in the frequency range from 18 to 26.5 GHz. Gaussian monocycle pulses with 70 ps pulsewidth were transmitted in the Si substrates successfully and the corresponding voltage gains were -23, -26, and -39 dB for the Si resistivities of 2290, 79.6, and 10 /spl Omega//spl middot/cm, respectively.     

Experimental and theoretical investigations on short-channel effects in 4H-SiC MOSFETs

In this paper, a fundamental investigation on short-channel effects (SCEs) in 4H-SiC MOSFETs is given. Planar MOSFETs with various channel lengths have been fabricated on p-type 4H-SiC (0001), (0001) and (1120) faces. In the fabricated MOSFETs, SCEs such as punchthrough behavior, decrease of threshold voltage, deterioration of subthreshold characteristics, and saturation of transconductance occur by reducing channel length. The critical channel lengths below which SCEs occur are analyzed as a function of p-body doping and oxide thickness by using device simulation. The critical channel lengths obtained from the device simulation is in good agreement with the empirical relationship for Si MOSFETs. The critical channel lengths in the fabricated SiC MOSFETs are slightly longer than simulation results. The dependence of crystal face orientations on SCEs is hardly observed. Impacts of interface charge on the appearance of SCEs are discussed.