Boosting Thermal Conductivity by Surface Plasmon Polaritons Propagating along a Thin Ti Film.

We experimentally demonstrate boosted in-plane thermal conduction by surface plasmon polaritons (SPPs) propagating along a thin Ti film on a glass substrate. Due to the lossy nature of metal, SPPs can propagate over centimeter-scale distances even along a supported metal film, and the resulting ballistic heat conduction can be quantitatively validated. Further, for a 100-nm-thick Ti film on a glass substrate, a significant enhancement of in-plane thermal conductivity compared to bulk value (∼25%) is experimentally shown. This Letter will provide a new avenue to employ SPPs for heat dissipation along a supported thin film, which can be readily applied to mitigate hot-spot issues in microelectronics.

Hyperbolic metamaterial-based near-field thermophotovoltaic system for hundreds of nanometer vacuum gap.

Artificially designed hyperbolic metamaterial (HMM) possesses extraordinary electromagnetic features different from those of naturally existing materials. In particular, the dispersion relation of waves existing inside the HMM is hyperbolic rather than elliptical; thus, waves that are evanescent in isotropic media become propagating in the HMM. This characteristic of HMMs opens a novel way to spectrally control the near-field thermal radiation in which evanescent waves in the vacuum gap play a critical role. In this paper, we theoretically investigate the performance of a near-field thermophotovoltaic (TPV) energy conversion system in which a W/SiO2-multilayer-based HMM serves as the emitter at 1000 K and InAs works as the TPV cell at 300 K. By carefully designing the thickness of constituent materials of the HMM emitter, the electric power of the near-field TPV devices can be increased by about 6 times at 100-nm vacuum gap as compared to the case of the plain W emitter. Alternatively, in regards to the electric power generation, HMM emitter at experimentally achievable 100-nm vacuum gap performs equivalently to the plain W emitter at 18-nm vacuum gap. We show that the enhancement mechanism of the HMM emitter is due to the coupled surface plasmon modes at multiple metal-dielectric interfaces inside the HMM emitter. With the minority carrier transport model, the optimal p-n junction depth of the TPV cell has also been determined at various vacuum gaps.

Graphene-assisted Si-InSb thermophotovoltaic system for low temperature applications.

The present work theoretically analyzes the performance of the near-field thermophotovoltaic (TPV) energy conversion device for low temperature applications (Tsource ∼ 500 K). In the proposed TPV system, doped Si is employed as the source because its optical property can be readily tuned by changing the doping concentration, and InSb is selected as a TPV cell because of its low bandgap energy (0.17 eV). In order to enhance the near-field thermal radiation between the source and the TPV cell, monolayer of graphene is coated on the cell side so that surface plasmon can play a critical role in heat transfer. It is found that monolayer of graphene can significantly enhance the power throughput by 30 times and the conversion efficiency by 6.1 times compared to the case without graphene layer. The resulting maximum conversion efficiency is 19.4% at 10-nm vacuum gap width.

Metal-Organic Frameworks as a Thermal Emitter for High-Performance Passive Radiative Cooling.

Passive radiative cooling represents a transformative approach to achieving sustainable cooling on Earth without relying on energy consumption. In this research, the optical characteristics of five readily accessible metal-organic frameworks (MOFs): ZIF-67(Co), MOF-74(Ni), HKUST-1(Cu), MOF-801(Zr), and UiO-66(Zr) are meticulously explored. The objective is to identify the pivotal factors that influence their ability to facilitate radiative cooling. Through an in-depth analysis encompassing spectroscopic features, surface texture, and porosity, it is found that the MOFs' cooling efficacy is largely influenced by their optical bandgaps and functional groups, although other factors like chemical composition and structural characteristics remain to be considered. Notably, UiO-66(Zr) emerged as the standout performer, boasting an impressive solar reflectance of 91% and a mid-infrared emissivity of 96.8%. Remarkably, a fabric treated with UiO-66(Zr) achieved a substantial sub-ambient cooling effect, lowering temperatures by up to 5 °C and delivering a cooling power of 26 W m-2 at 300 K. The findings underscore the vast potential of MOFs in offering new opportunities to advance passive radiative cooling technologies, paving the way for their extensive application in this field.

Near-field thermal radiation between graphene-covered doped silicon plates.

The present work describes a theoretical investigation of the near-field thermal radiation between doped Si plates coated with a mono-layer of graphene. It is found that the radiative heat flux between doped Si plates can be either enhanced or suppressed by introducing graphene layer, depending on the Si doping concentration and chemical potential of graphene. Graphene can enhance the heat flux if it matches resonance frequencies of surface plasmon at vacuum-source and vacuum-receiver interfaces. In particular, significant enhancement is achieved when graphene is coated on both surfaces that originally does not support the surface plasmon resonance. The results obtained in this study provide an important guideline into enhancing the near-field thermal radiation between doped Si plates by introducing graphene.

Fabrication of the microchannel by metal-organic framework, copper benzenetricarboxylate.

We successfully fabricated the metal-organic framework (MOF), copper benzenetricarboxylate on a microchannel system, which was able to solve the problems created by increased heat dissipation in small electronic equipment. The microchannel system was designed to make an entrance part that can control the reaction temperature, which was predicted through a heat transfer analysis and the finite element method with COMSOL Multiphysics. Synthetic conditions, synthesis time, temperature and microchannel size were systematically tuned for the selective fabrication of copper benzenetricarboxylate on a microchannel surface. Scanning electron microscope (SEM) images, selected area electron diffraction (SAED) pattern and Fourier transform infrared (FT-IR) data clearly demonstrated that copper benzenetricarboxylate was strongly adhered to the bottom surfaces of the microchannels. Moreover, the synthesis of MOF in the microchannel system provided a much faster growth rate and better crystallinity compared to a conventional synthesis method.

Fermented Platycodon grandiflorum Extracts Relieve Airway Inflammation and Cough Reflex Sensitivity In Vivo.

Platycodon grandiflorum (PG) has been extensively utilized as an herb to relieve phlegm. In this study, the effects of PG root extracts on airway inflammation and cough reflex were investigated, especially using fermented PG extracts (FPE) to increase an active compound, platycodin D by fermentation. FPE significantly reduced the numbers of eosinophils and total cells in the bronchoalveolar lavage fluid (BALF) obtained from lipopolysaccharide/ovalbumin (LPS/OVA)-induced asthma mice versus those of vehicle control. Moreover, in the BALF and the serum, FPE significantly reduced the concentration of IL-17E, a proinflammatory cytokine that causes TH2 immunity, including eosinophil amplification. It was also demonstrated that FPE might relieve inflammations through histological analysis of the lung separated from each mouse. Furthermore, in cough reflex guinea pigs induced by citric acid treatment, FPE treatment significantly reduced the number of coughs versus that of vehicle control, and consequently decreased cough reflex sensitivity. In addition, the total cell number and eosinophils significantly decreased in the BALF obtained from each guinea pig versus that of vehicle control. In in vitro study, pretreatment with FPE in LPS-stimulated RAW264.7 cells significantly reduced the levels of proinflammatory cytokines such as TNF-α, IL-6, and IL-1ß, and inducible nitric oxide synthases (iNOS). Therefore, we demonstrated that FPE relieved airway inflammation and cough reflex sensitivity in vivo, and exhibited anti-inflammatory effects through suppression of iNOS and several proinflammatory cytokines. These findings suggest that FPE might have a beneficial effect on respiratory health, and may be useful as a functional food to prevent respiratory diseases.

AFM-thermoreflectance for simultaneous measurements of the topography and temperature.

To understand the thermal failure mechanisms of electronic devices, it is essential to measure the temperature and characterize the thermal properties of individual nanometer-scale transistors in electronic devices. Previously, scanning thermal microscopy (SThM) has been used to measure the local temperature with nanometer-scale spatial resolutions using a probe with a built-in temperature sensor. However, this type of temperature measurement requires additional equipment to process the temperature-sensing signals and expensive temperature-sensor-integrated probes fabricated by complicated MEMS processes. Here, we present a novel technique which enables the simultaneous measurement of the temperature and topography of nanostructures only with a conventional atomic force microscope (AFM) of the type commonly used for topography measurements and without any modifications of the probe and extra accessories for data acquisition. The underlying principle of the proposed technique is that the local temperature of a specimen is estimated quantitatively from the thermoreflectance of a bare silicon AFM probe that is in contact with a specimen. The temperature obtained by our technique is found to be consistent with a result obtained by SThM measurements.

Tailoring near-field thermal radiation between metallo-dielectric multilayers using coupled surface plasmon polaritons.

Several experiments have shown a huge enhancement in thermal radiation over the blackbody limit when two objects are separated by nanoscale gaps. Although those measurements only demonstrated enhanced radiation between homogeneous materials, theoretical studies now focus on controlling the near-field radiation by tuning surface polaritons supported in nanomaterials. Here, we experimentally demonstrate near-field thermal radiation between metallo-dielectric multilayers at nanoscale gaps. Significant enhancement in heat transfer is achieved due to the coupling of surface plasmon polaritons (SPPs) supported at multiple metal-dielectric interfaces. This enables the metallo-dielectric multilayers at a 160-nm vacuum gap to have the same heat transfer rate as that between semi-infinite metal surfaces separated by only 75 nm. We also demonstrate that near-field thermal radiation can be readily tuned by modifying the resonance condition of coupled SPPs. This study will provide a new direction for exploiting surface-polariton-mediated near-field thermal radiation between planar structures.

Exosomal amyloid A and lymphatic vessel endothelial hyaluronic acid receptor-1 proteins are associated with disease activity in rheumatoid arthritis.

BACKGROUND: Exosomes are thought to play an important role in exchanging information between cells. The proteins and lipids in exosomes play roles in mediating inflammatory and autoimmune diseases. The aim of this study was to identify exosomal candidate proteins that are related to other inflammatory parameters in rheumatoid arthritis (RA). METHODS: The study population consisted of 60 patients with RA: 30 in the clinical remission (CR) group with a Disease Activity Score in 28 joints based on erythrocyte sedimentation rate (DAS28-ESR) ≤2.6 and 30 in the non-clinical remission (non-CR) group with a DAS28-ESR >2.6. Preparation of exosomes from patient serum samples was performed with the ExoQuick kit, and protein identification/quantification was performed using tandem mass tag labeling/mass spectrometry and an enzyme-linked immunosorbent assay. Comparisons between groups were made using Student's t test or the Mann-Whitney U test, as appropriate. Spearman's correlation coefficients (ρ) were calculated. RESULTS: We identified six candidate proteins. Exosomal levels of amyloid A (AA) and lymphatic vessel endothelial hyaluronic acid receptor-1 (LYVE-1) differed between the CR and non-CR groups. Both serum and exosomal AA levels were higher in the non-CR group than in the CR group (p = 0.001). Significant positive correlations were found between exosomal AA and C-reactive protein (CRP) as well as between serum AA and CRP (ρ = 0.614, p = 0.001, and ρ = 0.624, p = 0.001, respectively). Although serum levels of LYVE-1 did not differ between the non-CR and CR groups, exosomal levels of LYVE-1 were lower in the non-CR group than in the CR group (p = 0.01). We identified positive correlations between serum/exosomal LYVE-1 and CRP only in the non-CR group (serum ρ = 0.376, p = 0.04; exosome ρ = 0.545, p = 0.002). CONCLUSIONS: Exosomal LYVE-1 shows potential for use as an additional marker of disease activity in patients with RA, and exosomes may carry other useful markers for RA.

A Clinical Comparative Study of Ultrasound-Normal Versus Ultrasound-Abnormal Congenital Muscular Torticollis.

OBJECTIVE: To investigate the clinical features and outcome of outpatient-based physiotherapy (manual stretch) of congenital muscular torticollis (CMT) with passive neck motion limitation (≥ 10°) according to whether the finding on ultrasonography (US) is normal or abnormal. DESIGN: Case-control study. SETTING: Institutional practice. PARTICIPANTS: A total of 149 patients with CMT who met eligibility criteria were included: age at presentation ≤ 6 months, limitation of passive neck rotation (ΔROT) or lateral flexion (ΔLAT) ≥ 10°, and completion of our outpatient-based physiotherapy program. INTERVENTIONS: Patients were allocated to the US-normal or US-abnormal group. Patients underwent physiotherapy and were followed-up monthly until ΔROT and ΔLAT were ≤ 5° or did not respond to treatment. MAIN OUTCOME MEASUREMENTS: Baseline characteristics, initial ΔROT and ΔLAT, age at presentation, treatment durations, and success rates of physiotherapy were compared between 2 groups. Treatment duration was adjusted for initial ΔROT, ΔLAT, and age at presentation using analysis of covariance. RESULTS: Mean initial ΔROT and ΔLAT in US-abnormal (28.5°; 17.0°) were greater than in US-normal (7.9°, P < .001; 12.3°, P = .001, respectively). Mean age at presentation was older in US-normal (3.8 months) than in US-abnormal (1.8 months, P < .001). Treatment duration was shorter in the US-normal (5.1 weeks) than US-abnormal (14.9 weeks, P < .001). Adjusted treatment duration was also shorter in US-normal (9.7 weeks) than US-abnormal (13.8 weeks, P < .05). The success rates of physiotherapy were 95% in US-abnormal and 100% in US-normal. Two of 6 treatment failures in the US-abnormal group underwent surgery. CONCLUSIONS: In CMT with passive neck motion limitation (≥ 10°), patients in the US-normal group demonstrated lesser passive neck motion limitation and older age at presentation than US-abnormal. It seems that US-normal showed shorter treatment duration irrespective of severity of neck motion limitation and age at presentation. Additionally, manual stretching applied before 6 months of age appears to show generally good outcome regardless of US findings.