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We have demonstrated a highly stable electric heater made of oxidation-resistant MXene film, which was capable of stable operation in air under highly oxidizing conditions (70 °C, 100% RH).

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Gas molecules are known to interact with two-dimensional (2D) materials through surface adsorption where the adsorption-induced charge transfer governs the chemiresistive sensing of various gases. Recently, titanium carbide (Ti3C2T x ) MXene emerged as a promising sensing channel showing the highest sensitivity among 2D materials and unique gas selectivity. However, unlike conventional 2D materials, MXenes show metallic conductivity and contain interlayer water, implying that gas molecules will likely interact in a more complex way than the typical charge transfer model. Therefore, it is important to understand the role of all factors that may influence gas sensing. Here, we studied the gas-induced interlayer swelling of Ti3C2T x MXene thin films and its influence on gas sensing performance. In situ X-ray diffraction was employed to simultaneously measure dynamic swelling behavior where Ti3C2T x MXene films displayed selective swelling toward ethanol vapor over CO2 gas. Results show that the controlling sodium ion concentration in the interlayers is highly important in tuning the swelling behavior and gas sensing performance. The degree of swelling matched well with the gas response intensity, and the highest gas selectivity toward ethanol vapor was achieved for Ti3C2T x sensing channels treated with 0.3 mM NaOH, which also displayed the largest amount of swelling. Our results demonstrate that controlling the interlayer transport of Ti3C2T x MXene is essential for enhancing the selective sensing of gas molecules.

Abstract-In robotic single port surgery, it is desirable for a manipulator to exhibit the property of variable stiffness. Small port incisions may require both high flexibility of the manipulator for safety purposes, and high structural stiffness for operational precision and high payload capability. This paper presents a new hyper-redundant tubular manipulator with a variable neutral-line mechanisms and adjustable stiffness.A unique asymmetric arrangement of the tendons and the links realizes both articulation of the manipulator and continuous stiffness modulation. This asymmetric motion of the manipulator is compensated by a novel actuation mechanism without affecting its structural stiffness.The paper describes the basic mechanics of the variable neutral-line manipulator, and its stiffness characteristics. Simulation and experimental results verify the performance of the proposed mechanism.Index Terms -Variable neutral-line mechanism, snake-like manipulator, adjustable stiffness, medical robot.

Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3-hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs. In particular, the location of the QD arrays within the single strand of P3HT-b-P2VP can be controlled precisely by manipulating the regioregularity (RR) values of P3HT block and the relative lengths of P2VP block. The degree of coaxiality of the QD arrays was shown to depend on the coplanarity of the thiophene rings of P3HT block, which can be controlled by the RR value of P3HT block. In addition, the location of QDs could be regulated at the specific-local site of P3HT-b-P2VP NW according to the surface characteristics of QDs. As an example, the comparison of two different QDs coated with hydrophobic alkyl-terminated and hydroxyl-terminated molecules, respectively, is used to elucidate the effect of the surface properties of QDs on their nanolocation in the NW.

A layer-by-layer deposition of two conducting polymers, each layer of which is a few tenths of nanometer thick, has been successfully performed to enhance the thermoelectric power factor of organic thin films.

QS-21 is one of the most promising new adjuvants for immune response potentiation and dose-sparing in vaccine therapy given its exceedingly high level of potency and its favorable toxicity profile. Melanoma, breast cancer, small cell lung cancer, prostate cancer, HIV-1, and malaria are among the numerous maladies targeted in more than 80 recent and ongoing vaccine therapy clinical trials involving QS-21 as a critical adjuvant component for immune response augmentation. QS-21 is a natural product immunostimulatory adjuvant, eliciting both T-cell- and antibody-mediated immune responses with microgram doses. Herein is reported the synthesis of QS-21A(api) in a highly modular strategy, applying novel glycosylation methodologies to a convergent construction of the potent saponin immunostimulant. The chemical synthesis of QS-21 offers unique opportunities to probe its mode of biological action through the preparation of otherwise unattainable nonnatural saponin analogues.