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Molybdenum disulfide (MoS2) has been regarded as one of the most important n-type two-dimensional (2D) transition metal dichalcogenide semiconductors for nanoscale electron devices. Relatively high contact resistance (RC) remains as an issue in the 2D-devices yet to be resolved. Reliable technique is very compelling to practically produce low RC values in device electronics, although scientific approaches have been made to obtain a record-low RC. To resolve this practical issue, we here use thermal-evaporated ultrathin LiF between channel and source/drain metal to fabricate 2D-like MoS2 field effect transistors (FETs) with minimum RC. Under 4-bar FET method, RC less than ∼600 Ω·μm is achieved from the LiF/Au contact MoS2 FET. Our normal 2-bar FET with LiF thus shows the same mobility as that of 4-bar FET that should have no RC in principle. On the basis of these results, ultrathin LiF is also applied for transparent conducting oxide contact, successfully enabling transparent MoS2 FETs.

Background: There are several advantages of low flow anesthesia including safety, economics, and eco-friendliness. However, oxygen concentration of fresh gas flow and inspired gas are large different in low flow anesthesia. This is a hurdle to access to low flow anesthesia. In this study, we aimed to investigate the change in inhaled oxygen concentration in low flow anesthesia using oxygen and medical air.Methods: A total of 60 patients scheduled for elective surgery with an American Society of Anesthesiologist physical status I or II were enrolled and randomly allocated into two groups. Group H: Fresh gas flow rate (FGF) 4 L/min (FiO₂ 0.5). Group L: FGF 1 L/min (FiO₂ 0.5). FGF was applied 4 L/min in initial phase (10 min) after intubation. After initial phase FGF was adjusted according to groups. FGF continued at the end of surgery. Oxygen and inhalation anesthetic gas concentration were recorded for 180 min at 15 min interval.Results: The inspired oxygen concentration decreased by 5.5% during the first 15 min in the group L. Inspired oxygen decreased by 1.5% during next 15 min. Inspired oxygen decreased by 1.4% for 30 to 60 min. The inspired oxygen of group L is 35.4 ± 4.0% in 180 min. The group H had little difference in inspired oxygen concentration over time and decreased by 1.8% for 180 min.Conclusions: The inspired oxygen concentration is maintained at 30% or more for 180 min in patients under 90 kg. Despite some technical difficulties, low flow anesthesia may be considered.

Recently, organic photovoltaics (OPVs) have attracted attention as a next-generation energy source as their power conversion efficiency (PCE) has significantly improved. To increase the PCE of OPVs further, a fundamental understanding of material properties of a new organic semiconductor is highly important. Copper naphthalocyanine (CuNc) is composed of macrocyclic ligands with extended benzene rings of copper phthalocyanine (CuPc). Thus, it can be considered as a potential candidate for an efficient p-type organic semiconductor, similar to a well-known conventional p-type organic semiconductor CuPc. In this study, we investigated the electronic structure of thermally evaporated CuNc on indium tin oxide (ITO) wit in situ ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS) and density functional theory (DFT) calculations. DFT calculations predict that CuNc has a lower ionization energy (IE) and band gap than CuPc. However, the IE measured by UPS and the band gap measured by UV-vis absorption of the deposited film were much higher than CuPc. Derived from the measured UPS, XPS spectra and DFT calculation results, we concluded that CuNc could be decomposed with thermal evaporation in a vacuum and the pyrrole-based material might be deposited on ITO. The increased IE and band gap were attributed to the disappearance of the highest occupied molecular orbital originating from the macrocyclic ligands with D4h symmetry. Therefore, the thermal evaporation method would not be a suitable method to obtain the CuNc film for device application, and the alternative solution process at low temperature would be more adequate.

Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) films were fabricated using an electrospray deposition (ESD) method. The ESD PEDOT:PSS films exhibited higher PSS content on the surface than spin-coated PEDOT:PSS films, which results in a higher work function. Based on this result, metal-electrode-free inverted organic photovoltaics (OPVs) were fabricated. The ESD PEDOT:PSS was used as the top electrode on the poly(3-hexythiophene-2,5-diyl) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) light-absorbing layer. The power conversion efficiency (PCE) of OPVs was significantly increased with the 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile layer. The improved PCE would be attributed to the suppression of exciton quenching at the P3HT:PCBM and PEDOT:PSS interface.

Bis(trifluoromethane)sulfonimide lithium salt (Li-TFSI) has been popularly employed as an efficient p-dopant that increases the conductivity of a hole transport layer (HTL) in perovskite solar cells and dye-sensitized solar cells. However, the working mechanism of the Li-TFSI dopant is a long-standing question. The hygroscopicity of Li-TFSI makes it difficult to isolate the exact doping mechanism. In this study, we unveil the role of Li-TFSI in the p-doping to the N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) HTL. A series of systematic in situ measurements using ultraviolet and inverse photoelectron spectroscopy reveal that electron transfer from NPB to Li-TFSI occurs due to the lower-lying negative polaronic level of Li-TFSI rather than the positive polaronic level of NPB. The hole injection barrier between NPB and indium tin oxide is significantly reduced with Li-TFSI doping, enhancing the device performance of hole-only devices and organic light-emitting diodes dramatically. With excessive dopants, however, the agglomerative property of Li-TFSI became dominant, decreasing the doping efficiency. These results provide robust guidelines for developing an efficient doping method for a molecular system with high conductivity.

SnOx thin films were successfully deposited by the thermal atomic layer deposition (ALD) method using N,N′-tert-butyl-1,1-dimethylethylenediamine stannylene(II) as a precursor and ozone and water as reactants. The growth of SnO and SnO2 films could be easily controlled by employing different reactants and utilizing different ozone and water concentrations, respectively. The formation of both SnO and SnO2 films exhibited typical surface-limiting reaction characteristics, although their growth behaviors differ from one another. The combined studies of density functional theory calculations and experimental analyses showed that the difference in growth behavior of the SnO and SnO2 films can be attributed to the stability of ozone and water on the SnO2 and SnO films. SnO and SnO2 films have different crystal structures and both films were crystallized from the amorphous to polycrystalline states following an increase in the deposition temperature. The absorbance and refractive index of the thin films were inv...

In organolead halide perovskite solar cells (PSCs), interfacial properties between the perovskite and charge transport layers are the critical factors governing charge extraction efficiency. In this study, the effect of interfacial energetics between two-step spin-coated methylammonium lead iodide (MAPbI3) with different methylammonium iodide (MAI) concentrations and C60 on the charge extraction efficiency is investigated. The electronic structures of perovskite films are significantly varied by the MAI concentrations due to the changes in the residual precursor and MA+ defect content. As compared to the optimum PSCs with 25 mg mL–1 MAI, PSCs with other MAI concentrations show significantly lower power conversion efficiencies and severe hysteresis. The energy level alignment at the C60/MAPbI3 interface determined by ultraviolet and inverse photoelectron spectroscopy measurements reveals the origin of distinct differences in device performances. The conduction band offset at the C60/MAPbI3 interface plays ...

The effects of senescence associated secretory phenotype (SASP) from therapy-induced senescent endothelial cells on tumor microenvironment (TME) remains to be clarified. Here, we investigated effects of ionizing radiation (IR)- and doxorubicin-induced senescent HUVEC on TME. MDA-MB-231 cancer cells treated with conditioned medium (CM) from senescent HUVEC or co-cultured with senescent HUVEC significantly increased cancer cell proliferation, migration, and invasion. We found that CXCL11 plays a principal role in the senescent CM-induced aggressive activities of MDA-MB-231 cells. When we treated HUVEC with a neutralizing anti-CXCL11 antibody or CXCL11 SiRNA, or treated MDA-MB-231 cells with CXCR3 SiRNA, we observed synergistic diminution of the ability of the HUVEC SASP to alter the migration and spheroid invasion of cancer cells. ERK activation was involved in the HUVEC SASP-induced aggressive activity of MDA-MB-231 cells. Finally, we observed the in vivo effect of CXCL11 from the senescent HUVEC in tumor-bearing mice. Together, our results demonstrate that SASP from endothelial cells experiencing therapy-induced senescence promotes the aggressive behavior of cancer cells, and that CXCL11 can potentially be targeted to prevent the adverse effects of therapy-induced senescent endothelial cells on the tumor microenvironment.

Cellular senescence can be triggered by various intrinsic and extrinsic stimuli. We previously reported that silencing of 3'-phosphoadenosine 5'-phosphosulfate synthetase 2 (PAPSS2) induces cellular senescence through augmented fibroblast growth factor receptor 1 (FGFR1) signaling. However, the exact molecular mechanism connecting heparan sulfation and cellular senescence remains unclear. Here, we investigated the potential involvement of heparan sulfate proteoglycans (HSPGs) in augmented FGFR1 signaling and cellular senescence. Depletion of several types of HSPGs revealed that cells depleted of syndecan 1 (SDC1) exhibited typical senescence phenotypes, and those depleted of PAPSS2-, SDC1-, or heparan sulfate 2-O sulfotransferase 1 (HS2ST1) showed decreased FGFR1 internalization along with hyperresponsiveness to and prolonged activation of fibroblast growth factor 2 (FGF2)-stimulated FGFR1- v-akt murine thymoma viral oncogene homolog (AKT) signaling. Clathrin- and caveolin-mediated FGFR1 endocytosis contributed to cellular senescence through the FGFR1-AKT-p53-p21 signaling pathway. Dynasore treatment triggered senescence phenotypes, augmented FGFR1-AKT-p53-p21 signaling, and decreased SDC1 expression. Finally, the replicatively and prematurely senescent cells were characterized by decreases of SDC1 expression and FGFR1 internalization, and an increase in FGFR1-AKT-p53-p21 signaling. Together, our results demonstrate that properly sulfated SDC1 plays a critical role in preventing cellular senescence through the regulation of FGFR1 endocytosis.

Recently, a hole-transport-layer (HTL)-free structure was proposed to decrease the cost of organic lead halide perovskite solar cell (PSC) fabrication. In HTL-free PSCs, instead of using an HTL insertion, the HTL material can be added directly into a perovskite precursor solution to improve hole transport. For example, copper thiocyanate (CuSCN) is used for p-type doping of methylammonium lead triiodide (MAPI) via spin coating from a mixed solution. However, the optimum annealing temperature for CuSCN-doped MAPI (CuSCN:MAPI) PSCs is lower than the 100 °C that is typical for undoped MAPI PSCs. In this study, the origin of such lower annealing temperatures of CuSCN:MAPI PSCs is investigated. The highest power conversion efficiency (PCE) and enhanced electron transport in CuSCN:MAPI are obtained with annealing at 60 °C. Using transmission electron microscopy-energy-dispersive X-ray spectroscopy, it is revealed that annealing at 60 °C results in the uniform distribution of CuSCN, while the annealing at 100 °C induces the aggregation of CuSCN with a diameter of ~20 nm. A large energy barrier formed by the shallow-lying conduction band minimum of these CuSCN clusters hinders electron transport. The lower PCE of CuSCN:MAPI PSCs with annealing at 100 °C is attributed to this deterioration in the electron transport.

Cellular senescence refers to an irreversible growth arrest that is triggered by various intrinsic and extrinsic stresses. Many recent studies have demonstrated that cellular senescence plays a crucial role in the regression of tumors exposed to ionizing radiation (IR), but the underlying mechanism remains unknown. Here we show that the activation of integrin β4 is essential for IR-induced cellular senescence. IR treatment results in the phosphorylation of integrin β4 at tyrosine residue 1510, leading to activation of the integrin α6β4-Src-AKT signaling pathway. We further reveal that the IR-induced phosphorylation of integrin β4 is regulated by the cholesterol content and membrane fluidity. We also find that IR-induced p53-caspase signaling is independent of integrin α6β4-Src-AKT signaling. Finally, we show that siRNA- or inhibitor-mediated blockade of integrin α6β4-Src-AKT signaling switches the post-irradiation fate from senescence to apoptosis, under p53 activated condition, in both cancer cells and tumor tissues of xenograft mice. On the basis of our finding that, integrin α6β4 is specifically activated and acts primarily to induce premature senescence in irradiated cancer cells, we propose that this integrin may be a valuable target and biomarker for radiotherapy.

Elastomers show improved properties when reinforced with nanoclay at low filler loadings, but dispersion of the clay is difficult in non-polar polymers, such as ethylene propylene diene monomer (EPDM). In this work several compatibilization approaches were studied, including the addition of EPDM modified with maleic anhydride (EPDM-g-MA) and the use of organoclay modified with maleic anhydride-grafted liquid vinyl polybutadiene (LVPB-g-MA). The use of LVPB-g-MA-modified organoclay increased the degree of dispersion as measured by X-ray diffraction, giving increased thermal stability and modulus, and decreased swelling. Flame resistance was poorer for the EPDM/LVPB-g-MA- modified organoclay system compared to the unmodified EPDM/organoclay compound. The resistivity of the nanoclay-filled composites was lower than the reference EPDM compound, but dielectric properties for the LVPB-g-MA modified organoclay were similar to the reference.