The recent discovery of possible high-temperature (T(c)) superconductivity over 65 K in a monolayer FeSe film on SrTiO3 (refs 1-6) triggered a fierce debate on how superconductivity evolves from bulk ...to film, because bulk FeSe crystal exhibits a T(c) of no higher than 10 K (ref. 7). However, the difficulty in controlling the carrier density and the number of FeSe layers has hindered elucidation of this problem. Here, we demonstrate that deposition of potassium onto FeSe films markedly expands the accessible doping range towards the heavily electron-doped region. Intriguingly, we have succeeded in converting non-superconducting films with various thicknesses into superconductors with T(c) as high as 48 K. We also found a marked increase in the magnitude of the superconducting gap on decreasing the FeSe film thickness, indicating that the interface plays a crucial role in realizing the high-temperature superconductivity. The results presented provide a new strategy to enhance and optimize T(c) in ultrathin films of iron-based superconductors.
Geldanamycin, an ansamycin-derivative benzoquinone compound, was originally isolated as a natural product with anti-fungal activity. Later, geldanamycin was found to have anti-proliferative activity ...on tumor cells transformed by oncogene kinases such as v-Src. Geldanamycin neither bind nor inhibit oncogene kinases directly, but specifically binds and inhibits a major molecular chaperone, Hsp90. Hsp90 is a highly abundant and essential cytosolic protein and the expression level of Hsp90 increases by environmental stress. Hsp90 functions as a molecular chaperone by binding to various cellular proteins and supporting the proper folding, stability, and function of target proteins. The Hsp90 client proteins include a wide variety of signal-transducing proteins that regulate cell growth and differentiation, such as protein kinases and steroid hormone receptors. Hsp90 functions in an ATP-dependent manner in cooperation with other molecular chaperones such as Cdc37 and FKBP52. Geldanamycin specifically inhibits the essential ATPase activity of Hsp90. Thus, treatment of cells with geldanamycin results in inactivation, destabilization, and degradation of Hsp90 client proteins. Because Hsp90 client proteins play important roles in the regulation of the cell cycle, cell growth, cell survival, apoptosis, and oncogenesis, geldanamycin obstructs the proliferation of cancer cells and shows anti-cancer activity in experimental animals. Although difficulties with solubility and toxicity should be overcome, Hsp90 inhibitors will be potential and effective cancer chemotherapeutic drugs with a unique profile. In fact, a modified geldanamycin with lower toxicity, 17-allylaminogeldanamycin (17-AAG), has been examined in phase I clinical trials with encouraging results.
High-dose methotrexate (Hd-MTX) therapy has recently been applied to the treatment of adult acute lymphoblastic leukemia (ALL) based on pediatric protocols; however, its effectiveness for adult ALL ...has not yet been confirmed in a rigorous manner. We herein conducted a randomized phase III trial comparing Hd-MTX therapy with intermediate-dose (Id)-MTX therapy. This study was registered at UMIN-CTR (ID: C000000063). Philadelphia chromosome (Ph)-negative ALL patients aged between 25 and 64 years of age were enrolled. Patients who achieved complete remission (CR) were randomly assigned to receive therapy containing Hd-MTX (3 g/m
) or Id-MTX (0.5 g/m
). A total of 360 patients were enrolled. The CR rate was 86%. A total of 115 and 114 patients were assigned to the Hd-MTX and Id-MTX groups, respectively. The estimated 5-year disease-free survival rate of the Hd-MTX group was 58%, which was significantly better than that of the Id-MTX group at 32% (P=0.0218). The frequencies of severe adverse events were not significantly different. We herein demonstrated the effectiveness and safety of Hd-MTX therapy for adult Ph-negative ALL. Our results provide a strong rationale for protocols containing Hd-MTX therapy being applied to the treatment of adult ALL.
Encapsulation of β‐carotene inside single‐walled carbon nanotubes (SWCNTs) greatly improves the stability of β‐carotene. The Figure shows a schematic illustration of β‐carotene inside a SWCNT. The ...surrounding tube wall protects β‐carotene from reacting with radical species and suppresses its isomerization. This protection counters the degradation of π‐conjugated molecules, which is a bottleneck impeding their application in photonic devices.
Abstract
The broken inversion symmetry and time-reversal symmetry along with the large spin–orbit interactions in monolayer MoS
2
make it an ideal candidate for novel valleytronic applications. ...However, the realization of efficient spin-valley-controlled devices demands the integration of perpendicular magnetic anisotropy (PMA) electrodes with negligible Schottky barriers. Here, as the first demonstration, we fabricated a monolayer MoS
2
field-effect transistor with PMA electrodes: Pt/Co/Pt
3
and Co/Pt
2
. The
I
–
V
curves of PMA/MoS
2
contacts show symmetric and linear behavior reflecting Ohmic nature. The flat-band Schottky barrier heights (SBHs) extracted using the temperature and gate voltage dependence of the
I
–
V
curves were found to be 10.2 and 9.6 meV. The observed SBHs are record low values reported thus far for any metal/monolayer MoS
2
contact. High-quality PMA electrodes with almost zero SBH play a paramount role in the future development of novel spintronic/valleytronic devices; hence, our results can open a new route toward the realization of novel technological devices employing two-dimensional materials.
Abstract
Two-dimensional MoS
2
has emerged as promising material for nanoelectronics and spintronics due to its exotic properties. However, high contact resistance at metal semiconductor MoS
2
...interface still remains an open issue. Here, we report electronic properties of field effect transistor devices using monolayer MoS
2
channels and permalloy (Py) as ferromagnetic (FM) metal contacts. Monolayer MoS
2
channels were directly grown on SiO
2
/Si substrate via chemical vapor deposition technique. The increase in current with back gate voltage (
V
g
) shows the tunability of FET characteristics. The Schottky barrier height (SBH) estimated for Py/MoS
2
contacts is found to be +28.8 meV (at
V
g
= 0V), which is the smallest value reported so-far for any direct metal (magnetic or non-magnetic)/monolayer MoS
2
contact. With the application of positive gate voltage, SBH shows a reduction, which reveals ohmic behavior of Py/MoS
2
contacts. Low SBH with controlled ohmic nature of FM contacts is a primary requirement for MoS
2
based spintronics and therefore using directly grown MoS
2
channels in the present study can pave a path towards high performance devices for large scale applications.
This paper presents a novel design of a magnetically-sprung mechanical resonator for wideband vibration energy harvesting. In this design, a magnet composite consisting of two cylindrical magnets ...composed in a repelling arrangement is used as a moving mass, which is magnetically suspended between two ring magnets. This configuration yields more significant variation of stiffness in a shorter stroke compared with the previous design, resulting in wider operation band even under small excitation.
PDF
