Sivertsenashby1728

More efficient thermoelectric devices would revolutionize refrigeration and energy production, and low-dimensional thermoelectric materials are predicted to be more efficient than their bulk counterparts. But nanoscale thermoelectric devices generate thermal gradients on length scales that are too small to resolve with traditional thermometry methods. Here we fabricate, using single-crystal bismuth telluride (Bi2Te3) and antimony/bismuth telluride (Sb2-xBi x Te3) flakes exfoliated from commercially available bulk materials, functional thermoelectric coolers (TECs) that are only 100 nm thick. These devices are the smallest TECs ever demonstrated by a factor of 104. After depositing indium nanoparticles to serve as nanothermometers, we measure the heating and cooling produced by the devices with plasmon energy expansion thermometry (PEET), a high-spatial-resolution, transmission electron microscopy (TEM)-based thermometry technique, demonstrating a ΔT = -21 ± 4 K from room temperature. We also establish proof-of-concept for condensation thermometry, a quantitative temperature-change mapping technique with a spatial precision of ≲300 nm.Miniaturized total analysis systems, for the rapid detection of disease biomarkers, with features including high biomarker sensitivity, selectivity, biocompatibility, and disposability, all at low cost are of profound importance in the healthcare sector. Within this frame of reference, we developed a lab-on-a-carbohydrate-microneedle biodevice by integrating localized surface plasmon resonance (LSPR) paper-based substrates with biocompatible microneedles of high aspect ratio (>601 lengthwidth). These microneedles are completely fabricated with carbohydrate (maltose) and further coated with poly lactic-co-glycolic acid (PLGA), which together serves the purpose of fluid channels. The porous nature of PLGA, in addition to drawing blood by capillary action, filters out the whole blood, allowing only the blood plasma to reach the biorecognition layer of the developed biodevice. While the use of maltose provides biocompatibility to the microneedle, the axial compression and transverse load analysis revealed desired mechanical strength of the microneedle, with mechanical failure occurring at 11N and 9 N respectively for the compressive and transverse load. For a proof-of-principle demonstration, the developed biodevice is validated for its operational features by direct detection of cystatin C in finger-prick blood and up to a concentration of 0.01 μg/mL in buffered conditions using the LSPR technique. Furthermore, by changing the biorecognition layer, the use of the developed needle can be extended to other disease biomarkers, and therefore the innovation presented in this work represents a hallmark in the state of the art of lab-on-a-chip biodevices.Biocompatible nanoscale probes for sensitive detection of paramagnetic species and molecules associated with their (bio)chemical transformations would provide a desirable tool for a better understanding of cellular redox processes. Here, we describe an analytical tool based on quantum sensing techniques. We magnetically coupled negatively charged nitrogen-vacancy (NV) centers in nanodiamonds (NDs) with nitroxide radicals present in a bioinert polymer coating of the NDs. We demonstrated that the T1 spin relaxation time of the NV centers is very sensitive to the number of nitroxide radicals, with a resolution down to ∼10 spins per ND (detection of approximately 10-23 mol in a localized volume). The detection is based on T1 shortening upon the radical attachment, and we propose a theoretical model describing this phenomenon. We further show that this colloidally stable, water-soluble system can be used dynamically for spatiotemporal readout of a redox chemical process (oxidation of ascorbic acid) occurring near the ND surface in an aqueous environment under ambient conditions.As an excellent candidate for lightweight structural materials and nonmetal electrical conductors, carbon nanotube reinforced carbon matrix (CNT/C) composites have potential use in technologies employed in aerospace, military, and defense endeavors, where the combinations of light weight, high strength, and excellent conductivity are required. Both polymer infiltration pyrolysis (PIP) and chemical vapor infiltration (CVI) methods have been widely studied for CNT/C composite fabrications with diverse focuses and various modifications. Progress has been reported to optimize the performance of CNT/C composites from broad aspects, including matrix densification, CNT alignment, microstructure control, and interface engineering, etc. Recent approaches, such as using resistance heating for PIP or CVI, contribute to the development of CNT/C composites. To deliver a timely and up-to-date overview of CNT/C composites, we have reviewed the most recent trends in fabrication processes, summarized the mechanical reinforcement mechanism, and discussed the electrical and thermal properties, as well as relevant case studies for high-temperature applications. Conclusions and perspectives addressing future routes for performance optimization are also presented. Hence, this review serves as a rundown of recent advances in CNT/C composites and will be a valuable resource to aid future developments in this field.Dendritic cells (DCs) are highly effective antigen-presenting cells that shape immune responses. Vaccines that deliver antigen to the DCs can harness their power. DC surface lectins recognize glycans not typically present on host tissue to facilitate antigen uptake and presentation. Vaccines that target these surface lectins should offer improved antigen delivery, but their efficacy will depend on how lectin targeting influences the T cell subtypes that result. We examined how antigen structure influences uptake and signaling from the C-type lectin DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin or CD209). Virus-like particles (VLPs) were engineered from bacteriophage Qβ to present an array of mannoside ligands. The VLPs were taken up by DCs and efficiently trafficked to endosomes. The signaling that ensued depended on the ligand displayed on the VLP only those particles densely functionalized with an aryl mannoside, Qβ-Man540, elicited DC maturation and induced the expression of the proinflammatory cytokines characteristic of a T helper type 1 (TH1)-like immune response. This effect was traced to differential binding to DC-SIGN at the acidic pH of the endosome. Mice immunized with a VLP bearing the aryl mannoside, and a peptide antigen (Qβ-Ova-Man540) had antigen-specific responses, including the production of CD4+ T cells producing the activating cytokines interferon-γ and tumor necrosis factor-α. A TH1 response is critical for intracellular pathogens (e.g., viruses) and cancer; thus, our data highlight the value of targeting DC lectins for antigen delivery and validate the utility of DC-targeted VLPs as vaccine vehicles that induce cellular immunity.Quasi-two-dimensional (2D) organic-inorganic hybrid perovskite is a re-emerging material with strongly excitonic absorption and emission properties that are attractive for photonics and optoelectronics. Here we report the experimental observation of excitonic energy transfer (ET) in van der Waals heterostructures consisting of quasi-2D hybrid perovskite (C6H5C2H4NH3)2PbI4 (PEPI) and monolayer WS2. Photoluminescence excitation spectroscopy reveals a distinct ground exciton resonance feature of perovskite, evidencing ET from perovskite to WS2. We find unexpectedly high photoluminescence enhancement factors of up to ∼8, which cannot be explained by single-interface ET. Our analysis reveals that interlayer ET across the bulk of the layered perovskite also contributes to the large enhancement factor. Further, from the weak temperature dependence of the lower-limit ET rate, which we found to be ∼3 ns-1, we conclude that the Förster-type mechanism is responsible.Controlled plastic forming of nanoscale metallic objects by applying mechanical load is a challenge, since defect-free nanocrystals usually yield at near theoretical shear strength, followed by stochastic dislocation avalanches that lead to catastrophic failure or irregular, uncontrolled shapes. Herein, instead of mechanical load, we utilize chemical stress from imbalanced interdiffusion to manipulate the shape of nanowhiskers. Bimetallic Au-Fe nanowhiskers with an ultrahigh bending strength were synthesized employing the molecular beam epitaxy technique. The one-sided Fe coating on the defect-free, single-crystalline Au nanowhisker exhibited both single- and polycrystalline regions. Annealing the bimetallic nanowhiskers at elevated temperatures led to gradual change of curvature and irreversible bending. At low homological temperatures at which grain boundary diffusion is a dominant mode of mass transport this irreversible bending was attributed to the grain boundary Kirkendall effect during the diffusion of Au along the grain boundaries in the Fe layer. At higher temperatures and longer annealing times, the bending was dominated by intensive bulk diffusion of Fe into the Au nanowhisker, accompanied by a significant migration of the Au-Fe interphase boundary toward the Fe layers. The irreversible bending was caused by the concentration dependence of the lattice parameter of the Au(Fe) alloy and by the volume effect associated with the interphase boundary migration. The results of this study demonstrate a high potential of chemical interdiffusion in the controlled plastic forming of ultrastrong metal nanostructures. By design of the thickness, microstructure, and composition of the coating as well as the parameters of heat treatment, bimetallic nanowhiskers can be bent in a controlled manner.The electrocatalytic reduction of CO2 (CO2ER) to liquid fuels is important for solving fossil fuel depletion. However, insufficient insight into the reaction mechanisms renders a lack of effective regulation of liquid product selectivity. Here, in situ surface-enhanced Raman spectroscopy (SERS) empowered by 13C/12C isotope exchange is applied to probing the CO2ER process on nanoporous silver (np-Ag). Direct spectroscopic evidence of the preliminary intermediates, *COOH and *OCO-, indicates that CO2 is coordinated to the catalyst via diverse adsorption modes. Further, the relative Raman intensities of the above intermediates vary notably on np-Ag modified by Cu or Pd, and the liquid product selectivity also changes accordingly. Combined with density functional theory calculations, this study demonstrates that the CO2 adsorption configuration is a critical factor governing the reaction selectivity. Meanwhile, *COOH and *OCO- are key targets in the initial stage regulating liquid product selectivity, which could facilitate future selective catalyst design.Liver injury can result in different hepatic diseases such as fatty liver, liver fibrosis, hepatitis, and liver failure, which are mainly responsible for global mortality and morbidity. Early diagnosis is critical for the treatment of liver diseases. Herein we report luminescence imaging of neutrophil-mediated acute liver injury, including alcoholic liver injury (ALI) and acute liver failure (ALF). To this purpose, a biodegradable luminescent material was developed by chemical functionalization of a cyclic oligosaccharide, which can be produced into nanoprobes (defined as LaCD NPs). Luminescence of LaCD NPs was dependent on the level of reactive oxygen species and myeloperoxidase (MPO). Correspondingly, activated neutrophils could be specifically imaged by LaCD NPs, and the luminescent signal was positively associated with the neutrophil count. In mouse models of ALI and ALF, LaCD NPs enabled precise quantification and tracking of neutrophils in livers. learn more In both cases, changes in the luminescence intensity are consistent with time-dependent profiles of neutrophils, MPO, and other parameters relevant to the pathogenesis of liver injury.