Electric-field Control of Electronic States in WS<sub>2</sub> Nanodevices by Electrolyte Gating

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape ...

The University of Tokyo

the university of tokyo

In articular chondrocytes, the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) induces the expression of bone morphogenetic protein-2 (BMP-2), a growth factor known to be involved in the induction of cartilage and bone. A study was performed to clarify the mechanism(s) underlying the induction of BMP-2 in chondrogenic ATDC5 cells and primary cultured adult human articular chondrocytes. In ATDC5 cells, the endogenous BMP-2 expression was consistently low throughout the process of chondrogenic differentiation, and TNF-alpha induced BMP-2 expression only after the cells acquired the chondrogenic phenotype. The results of nuclear run-off assay and cycloheximide treatment consistently indicated that ATDC5 cells acquire the capacity to synthesize BMP-2 mRNA in the nuclei during the differentiation process. In an attempt to explain the discrepancy between the active nuclear mRNA synthesis and the observed low expression level in differentiated ATDC5 cells, the stability of BMP-2 mRNA was evaluated, and the cells were found to regulate the expression of BMP-2 at the post-transcriptional level. Human chondrocytes were confirmed to have a similar post-transcriptional regulation. The result of 3'-rapid amplification of cDNA end revealed that both human and mouse BMP-2 mRNAs contain multiple pentameric AUUUA motifs in a conserved manner in the 3'-untranslated regions, and transient transfection experiments demonstrated that TNF-alpha increases the stability of BMP-2 mRNA through the pentameric motifs. Further experiments revealed that TNF-alpha modulates mRNA stability via p38 signal transduction pathway, whereas the cytokine also augmented the expression of BMP-2 through transcriptional up-regulation via the transcriptional factor NF-kappaB.

Pro-inflammatory cytokine tumor necrosis factor-alpha induces bone morphogenetic protein-2 in chondrocytes via mRNA stabilization and transcriptional up-regulation.

Functionalities of two-dimensional (2D) crystals based on semiconducting transition metal dichalcogenides (TMDs) have now stemmed from simple field effect transistors (FETs) to a variety of electronic and opto-valleytronic devices, and even to superconductivity. Among them, superconductivity is the least studied property in TMDs due to methodological difficulty accessing it in different TMD species. Here, we report the systematic study of superconductivity in MoSe2, MoTe2 and WS2 by ionic gating in different regimes. Electrostatic gating using ionic liquid was able to induce superconductivity in MoSe2 but not in MoTe2 because of inefficient electron accumulation limited by electronic band alignment. Alternative gating using KClO4/polyethylene glycol enabled a crossover from surface doping to bulk doping, which induced superconductivities in MoTe2 and WS2 electrochemically. These new varieties greatly enriched the TMD superconductor families and unveiled critical methodology to expand the capability of ionic gating to other materials.

Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating.

We report an electric field tuning of the thermopower in ultrathin WSe2 single crystals over a wide range of carrier concentration by using electric double-layer (EDL) technique. We succeeded in the optimization of power factor not only in the hole but also in the electron side, which has never been chemically accessed. The maximized values of power factor are one-order larger than that obtained by changing chemical composition, reflecting the clean nature of electrostatic doping.

Gate-Optimized Thermoelectric Power Factor in Ultrathin WSe2 Single Crystals.

The regulatory T cells (Treg) with the most potent immunosuppressive activity are the effector Tregs (eTreg) with a CD45RA(-)Foxp3(++)CCR4(+) phenotype. Adult T-cell leukemia (ATL) cells often share the Treg phenotype and also express CCR4. Although mogamulizumab, a monoclonal antibody to CCR4, shows marked antitumor effects against ATL and peripheral T-cell lymphoma, concerns have been raised that it may induce severe autoimmune immunopathology by depleting eTregs. Here, we present case reports for two patients with ATL who responded to mogamulizumab but developed a severe skin rash and autoimmune brainstem encephalitis. Deep sequencing of the T-cell receptor revealed that ATL cells and naturally occurring Tregs within the cell population with a Treg phenotype can be clearly distinguished according to CADM1 expression. The onset of skin rash and brainstem encephalitis was coincident with eTreg depletion from the peripheral blood, whereas ATL relapses were coincident with eTreg recovery. These results imply that eTreg numbers in the peripheral blood sensitively reflect the equilibrium between antitumor immunity and autoimmunity, and that mogamulizumab might suppress ATL until the eTreg population recovers. Close monitoring of eTreg numbers is crucial if we are to provide immunomodulatory treatments that target malignancy without severe adverse events. Cancer Immunol Res; 4(8); 644-9. ©2016 AACR.

Effector Regulatory T Cells Reflect the Equilibrium between Antitumor Immunity and Autoimmunity in Adult T-cell Leukemia.

Electric field-induced p-n junctions are often used to realize peculiar functionalities in various materials. This method can be applied not only to conventional semiconductors but also to carbon nanotubes, graphene, and organic semiconductors to which the conventional chemical doping method is difficult to apply. Transition-metal dichalcogenides (TMDs) are one of such materials where the field-induced p-n junctions play crucial roles in realizing solar cell and light-emitting diode operations as well as circularly polarized electroluminescence. Although the field-induced p-n junction is a well-established technique, many of its physical properties are left to be understood because their doping mechanism is distinct from that of conventional p-n junctions. Here we report a direct electrical measurement of the potential variation along the field-induced p-n junction using multiple pairs of voltage probes. We detected the position of the junction, estimated the built-in potential, and monitored the effect of the bias voltage. We found that the built-in potential becomes negative under a forward bias voltage range where field-induced TMD p-n junctions have been operated as light-emitting diodes. This feature well reproduced the circularly polarized electroluminescence from the WSep-n junction, indicating that the present observation provides a useful background for understanding and functionalizing field-induced p-n junctions.

Potential Profile of Stabilized Field-Induced Lateral p-n Junction in Transition-Metal Dichalcogenides.

To facilitate the optimization of cancer immunotherapy lacking immune-related adverse events, we performed TCR repertoire analysis of tumor-infiltrating CD8T-cells in B16 melanoma-bearing mice receiving anti-PD-1, anti-CTLA-4, anti-4-1BB, anti-CD4 or a combination of anti-PD-1 and 4-1BB antibodies. Although CD8T-cells in the tumor were activated and expanded to a greater or lesser extent by these therapies, tumor growth suppression was achieved only by anti-PD-1, anti-PD-1/4-1BB combined, or by anti-CD4 treatment, but not by anti-CTLA-4 or anti-4-1BB monotherapy. Increased CD8T cell effector function and TCR diversity with enrichment of certain TCR clonotypes in the tumor was associated with anti-tumor effects. In contrast, polyclonal activation of T-cells in the periphery was associated with tissue damage. Thus, optimal combination therapy increases TCR diversity with extended activation of selective CD8T-cells specifically in the tumor but not in the periphery. Incorporation of the concept of evenness for the TCR diversity is proposed.

Ryuji Suzuki

Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics

The University of Tokyo

Electric-field Control of Electronic States in WS₂ Nanodevices by Electrolyte Gating

Ryuji Suzuki

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics

The University of Tokyo

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics

Electric-field Control of Electronic States in WS₂ Nanodevices by Electrolyte Gating