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1.
Small ; 19(14): e2205202, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36634999

RESUMEN

Thermoelectric technology, which has been receiving attention as a sustainable energy source, has limited applications because of its relatively low conversion efficiency. To broaden their application scope, thermoelectric materials require a high dimensionless figure of merit (ZT). Porous structuring of a thermoelectric material is a promising approach to enhance ZT by reducing its thermal conductivity. However, nanopores do not form in thermoelectric materials in a straightforward manner; impurities are also likely to be present in thermoelectric materials. Here, a simple but effective way to synthesize impurity-free nanoporous Bi0.4 Sb1.6 Te3 via the use of nanoporous raw powder, which is scalably formed by the selective dissolution of KCl after collision between Bi0.4 Sb1.6 Te3 and KCl powders, is proposed. This approach creates abundant nanopores, which effectively scatter phonons, thereby reducing the lattice thermal conductivity by 33% from 0.55 to 0.37 W m-1 K-1 . Benefitting from the optimized porous structure, porous Bi0.4 Sb1.6 Te3 achieves a high ZT of 1.41 in the temperature range of 333-373 K, and an excellent average ZT of 1.34 over a wide temperature range of 298-473 K. This study provides a facile and scalable method for developing high thermoelectric performance Bi2 Te3 -based alloys that can be further applied to other thermoelectric materials.

2.
Langmuir ; 33(10): 2590-2595, 2017 03 14.
Artículo en Inglés | MEDLINE | ID: mdl-28005379

RESUMEN

The bioinspired design of ligands for nanoparticle coating with remarkable precision in controlling anisotropic connectivity and with universal binding efficiency to the membrane has made a great impact on nanoparticle self-assembly. We utilize the HIV-1-derived trans-activator of transcription peptide (TAT), a member of the cell-penetrating peptides, as a soft shell coating on gold nanoparticles (GNPs) and characterize TAT pepide-mediated binding behaviors of GNPs on the lipid membrane. Whereas the peptides enable GNPs to firmly attach to the membrane, the binding structures are driven by two electrostatic forces: the interparticle peptide repulsion and the peptide-membrane attraction. Although transmission electron microscopy images showed that the densities of membrane-embedded GNPs were almost equal, X-ray reflectivity revealed a significant difference in binding structures of GNPs along the surface normal upon the increase of charge densities (ϕ) of the membrane. In particular, GNPs were densely suspended at ϕ = 70% while they adopted an additional well-defined layer underneath the membrane at ϕ = 100%, in addition to a translocation of the initially bound particles into the membrane. The observed behaviors of GNPs manifest a 3D to 2D transformation of the self-assembled structures from the diffused state to the closely packed state with the increase in the charge density of the membrane. The present study also provides insights on the binding mechanisms of the cell-penetrating peptide-coated nanoparticles to the lipid membranes, which is a common theme of delivery systems in pharmaceutical research.


Asunto(s)
Nanopartículas del Metal , Fenómenos Biofísicos , Oro , Infecciones por VIH , Lípidos
3.
J Nanosci Nanotechnol ; 14(7): 5103-8, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24757986

RESUMEN

The effect of non-conductive nano-particles on the electrical percolating network formation and the electrical conductivity of conductive nano-particles in polymer matrices is investigated using Monte Carlo simulations and a percolation theory. Both conductive and non-conductive nano-particles are modeled as spheres but with different diameters. Non-conductive nano-particles are up to four times bigger than conductive nano-particles. Equilibrated configurations for mixtures of nano-particles are obtained via Monte Carlo simulations and are used to estimate the probability (P) of forming an electrical percolating network and the percolation threshold conductive nano-particle volume fraction (phi(c)). As the volume fraction (phi(nc)) of non-conductive nano-particles increases, phi(c) decreases significantly, thus increasing the electrical conductivity. When non-conductive nano-particles mix with conductive nano-particles, they make the effective interaction energy W(r) between conductive nano-particles attractive, which should facilitate the formation of the electrical percolating network. For a given phi(nc), phi(c) increases slightly with an increase in the non-conductive nano-particle diameter (sigma(nc)). We also carry out simulations with non-conductive nano-particles of different structures and find that phi(c) is relatively insensitive to the non-conductive nano-particle structure.

4.
J Nanosci Nanotechnol ; 14(8): 6309-13, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25936109

RESUMEN

The direct spontaneous grafting of 4-nitrophenyl molecules onto n-doped hydrogenated amorphous silicon (a-Si:H) surfaces without external ultraviolet, thermal, or electrochemical energy was invegtigated. Clean n-doped a-Si:H thin films were dipped in a solution of 4-nitrobenzenediazonium salts (PNBD) in acetonitrile. After the modified surfaces were rinsed, they were analyzed qualitatively and quantitatively by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS and AFM results show that the reaction of an n-doped a-Si:H thin film with PNBD self-terminates without polymerization, after 5 h, and the surface number density of 4-nitrophenyl molecules is 4.2 x 10(15)/cm2. These results demonstrate that the spontaneous grafting of nitrophenyl layers onto n-doped a-Si:H thin films is an attractive pathway toward forming interfaces between a-Si:H and organic layers under ambient conditions.


Asunto(s)
Silicio/química , Hidrógeno/química , Microscopía de Fuerza Atómica , Espectroscopía de Fotoelectrones , Propiedades de Superficie
5.
J Korean Med Sci ; 29(5): 662-8, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24851022

RESUMEN

The risk of asthma has been increasing in parallel with use of acetaminophen, which is a potential source of oxidative stress. Toll-like receptor 4 (TLR4) plays a critical role not only in innate immunity, but also in mediating reactive oxygen species induced inflammation. Therefore, we investigated associations between acetaminophen usage and TLR4 polymorphism on asthma and bronchial hyperresponsiveness (BHR). The number of 2,428 elementary school children in Seoul and Jeongeup cities was recruited. Subjects who used acetaminophen with a family history of asthma had an increased risk of both asthma diagnosis ever and current asthma. Individuals with CT+TT genotypes at the TLR4 polymorphism, in combination with acetaminophen usage, also demonstrated an increased risk of asthma diagnosis ever (aOR, 2.08; 95% confidence interval [CI], 1.10-3.92). Family history of asthma and acetaminophen usage were risk factors for BHR. Although TLR4 was not an independent risk factor for BHR, individuals with CT+TT genotypes at the TLR4 polymorphism had an increased risk of BHR when combined with acetaminophen usage (aOR, 1.74; 95% CI, 1.03-2.94). In conclusion, acetaminophen usage may be associated with asthma and BHR in genetically susceptible subjects. This effect may be modified by polymorphism at TLR4.


Asunto(s)
Acetaminofén/efectos adversos , Asma/genética , Hiperreactividad Bronquial/genética , Receptor Toll-Like 4/genética , Acetaminofén/uso terapéutico , Adolescente , Asma/inducido químicamente , Asma/epidemiología , Hiperreactividad Bronquial/inducido químicamente , Hiperreactividad Bronquial/epidemiología , Niño , Estudios Transversales , Eosinófilos/inmunología , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Inmunoglobulina E/sangre , Inmunoglobulina E/inmunología , Inflamación/inmunología , Masculino , Estrés Oxidativo/efectos de los fármacos , Polimorfismo de Nucleótido Simple , Especies Reactivas de Oxígeno/inmunología , Riesgo , Factores de Riesgo , Encuestas y Cuestionarios
6.
Int J Mol Sci ; 15(11): 19342-54, 2014 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-25347273

RESUMEN

The effects of processed Aloe vera gel (PAG) on cyclophosphamide (CP)-induced immunotoxicity were examined in mice. Intraperitoneal injection of CP significantly reduced the total number of lymphocytes and erythrocytes in the blood. Oral administration of PAG quickly restored CP-induced lymphopenia and erythropenia in a dose-dependent manner. The reversal of CP-induced hematotoxicity by PAG was mediated by the functional preservation of Peyer's patch cells. Peyer's patch cells isolated from CP-treated mice, which were administered PAG, produced higher levels of T helper 1 cytokines and colony-stimulating factors (CSF) in response to concanavalin A stimulation as compared with those isolated from CP-treated control mice. PAG-derived polysaccharides directly activated Peyer's patch cells isolated from normal mice to produce cytokines including interleukin (IL)-6, IL-12, interferon-γ, granulocyte-CSF, and granulocyte-macrophage-CSF. The cytokines produced by polysaccharide-stimulated Peyer's patch cells had potent proliferation-inducing activity on mouse bone marrow cells. In addition, oral administration of PAG restored IgA secretion in the intestine after CP treatment. These results indicated that PAG could be an effective immunomodulator and that it could prevent CP-induced immunotoxic side effects.


Asunto(s)
Aloe/química , Ciclofosfamida/toxicidad , Geles/farmacología , Inmunosupresores/toxicidad , Administración Oral , Anemia/inducido químicamente , Anemia/tratamiento farmacológico , Animales , Células de la Médula Ósea/efectos de los fármacos , Células de la Médula Ósea/metabolismo , Citocinas/biosíntesis , Femenino , Geles/administración & dosificación , Geles/química , Inmunoglobulina A Secretora/biosíntesis , Inmunomodulación/efectos de los fármacos , Linfopenia/inducido químicamente , Linfopenia/tratamiento farmacológico , Ratones , Peso Molecular , Ganglios Linfáticos Agregados/efectos de los fármacos , Ganglios Linfáticos Agregados/inmunología , Ganglios Linfáticos Agregados/metabolismo , Polisacáridos/administración & dosificación , Polisacáridos/química , Polisacáridos/farmacología , Sustancias Protectoras/administración & dosificación , Sustancias Protectoras/química , Sustancias Protectoras/farmacología
7.
ACS Appl Mater Interfaces ; 16(19): 25071-25079, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38691640

RESUMEN

We propose a novel design of thermoelectric (TE) effect-based soft temperature sensors for directly monitoring localized subtle temperature stimuli. This design integrates rheology-engineered three-dimensional (3D) printing of high-performance carbon-based TE materials and polymer-based viscoelastic materials with low thermal conductivity. Rheological engineering of carbon nanotube (CNT) TE inks ensures the 3D printing of highly sensitive TE sensing units on directly written 3D soft platforms. Additionally, we pre-dope CNT inks with p- and n-type organic dopants to achieve high sensitivity and a fast response to temperature changes. The introduced 3D soft platforms with low thermal conductivity lead to an efficient thermal gradient on TE sensing units in the out-of-plane direction. Furthermore, encapsulating the temperature sensor array with the same polymer-based materials as the 3D soft platforms facilitates independent detection of localized temperature stimuli by minimizing thermal interaction between sensing units, resulting in precise temperature mapping by localized detection. Our 3D-printed soft temperature sensors exhibit high sensitivity to relatively small temperature changes, with a minimum sensing resolution of 0.1 K within tens of milliseconds. Moreover, the temperature sensor array not only detects localized temperature stimuli by imaging the temperature distribution but also demonstrates remarkable mechanical reliability against repetitive deformation with high accuracy.

8.
ACS Appl Mater Interfaces ; 16(14): 17683-17691, 2024 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-38531014

RESUMEN

Porous thermoelectric materials offer exciting prospects for improving the thermoelectric performance by significantly reducing the thermal conductivity. Nevertheless, porous structures are affected by issues, including restricted enhancements in performance attributed to decreased electronic conductivity and degraded mechanical strength. This study introduces an innovative strategy for overcoming these challenges using porous Bi0.4Sb1.6Te3 (BST) by combining porous structuring and interface engineering via atomic layer deposition (ALD). Porous BST powder was produced by selectively dissolving KCl in a milled mixture of BST and KCl; the interfaces were engineered by coating ZnO films through ALD. This novel architecture remarkably reduced the thermal conductivity owing to the presence of several nanopores and ZnO/BST heterointerfaces, promoting efficient phonon scattering. Additionally, the ZnO coating mitigated the high resistivity associated with the porous structure, resulting in an improved power factor. Consequently, the ZnO-coated porous BST demonstrated a remarkable enhancement in thermoelectric efficiency, with a maximum zT of approximately 1.53 in the temperature range of 333-353 K, and a zT of 1.44 at 298 K. Furthermore, this approach plays a significant role in enhancing the mechanical strength, effectively mitigating a critical limitation of porous structures. These findings open new avenues for the development of advanced porous thermoelectric materials and highlight their potential for precise interface engineering through the ALD.

9.
Antimicrob Resist Infect Control ; 12(1): 135, 2023 11 28.
Artículo en Inglés | MEDLINE | ID: mdl-38012753

RESUMEN

BACKGROUND: Multidrug-resistant organism (MDRO) screening may identify high-risk patients for MDRO infection and curb the spread of these resistant pathogens. However, the heterogeneous practices in MDRO screening and the diversity of MDRO risk factors necessitate a tailored approach for successful implementation. This study aimed to evaluate the performance of tailored MDRO screening in predicting MDRO carriage compared to universal screening. METHODS: Critically ill patients who underwent MDRO screening tests upon intensive care unit admission between September 2015 and December 2019 were included in the study. A risk-predicting model was developed using risk factors identified through multivariable logistic regression analysis. If an individual had one or more identified risk factors, the individual was deemed to be at risk of MDRO carriage and undergo tailored screening. The sensitivity of tailored screening was compared with universal screening for methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Gram-negative bacilli (carbapenem-resistant Acinetobacter baumannii and carbapenem-resistant Enterobacterales). RESULTS: The use of tracheostomy or endotracheal tubes, previous antibiotic exposure, previous multidrug-resistant Gram-negative bacilli carriage history, admission to the medical department, peripheral vascular disease, and liver disease were associated with positive screening for multidrug-resistant Gram-negative bacilli. These six risk factors accounted for all positive screening for multidrug-resistant Gram-negative bacilli, requiring 38.6% of all tests. Notably, MRSA had different risk factor profiles, and the risk factor-based screening approach detected only 43.1% (31 out of 72) of MRSA-positive cases. CONCLUSIONS: Tailored screening based on identified risk factors showed variable sensitivities to individual MDROs compared to universal screening. A tailored screening approach for individual MDROs may enhance the overall effectiveness of MDRO screening programs.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Humanos , Farmacorresistencia Bacteriana Múltiple , Emiratos Árabes Unidos/epidemiología , Enterococcus , Carbapenémicos , Unidades de Cuidados Intensivos
10.
Langmuir ; 28(33): 12085-93, 2012 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-22746250

RESUMEN

The UV-induced photochemical grafting of terminal alkenes has emerged as a versatile way to form molecular layers on semiconductor surfaces. Recent studies have shown that grafting reactions can be initiated by photoelectron emission into the reactant liquid as well as by excitation across the semiconductor band gap, but the relative importance of these two processes is expected to depend on the nature of the semiconductors, the reactant alkene and the excitation wavelength. Here we report a study of the wavelength-dependent photochemical grafting of alkenes onto single-crystal TiO(2) samples. Trifluoroacetamide-protected 10-aminododec-1-ene (TFAAD), 10-N-BOC-aminodec-1-ene (t-BOC), and 1-dodecene were used as model alkenes. On rutile (110), photons with energy above the band gap but below the expected work function are not effective at inducing grafting, while photons with energy sufficient to induce electronic transitions from the TiO(2) Fermi level to electronic acceptor states of the reactant molecules induce grafting. A comparison of rutile (110), rutile (001), anatase (001), and anatase (101) samples shows slightly enhanced grafting for rutile but no difference between crystal faces for a given crystal phase. Hydroxylation of the surface increases the reaction rate by lowering the work function and thereby facilitating photoelectron ejection into the adjacent alkene. These results demonstrate that photoelectron emission is the dominant mechanism responsible for grafting when using short-wavelength (~254 nm) light and suggest that photoemission events beginning on mid-gap states may play a crucial role.


Asunto(s)
Alquenos/química , Procesos Fotoquímicos , Titanio/química , Cristalografía por Rayos X , Propiedades de Superficie
11.
ACS Nano ; 16(2): 2271-2281, 2022 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-35060720

RESUMEN

For next-generation wearable and implantable devices, energy storage devices should be soft and mechanically deformable and easily printable on any substrate or active devices. Herein, we introduce a fully stretchable lithium-ion battery system for free-form configurations in which all components, including electrodes, current collectors, separators, and encapsulants, are intrinsically stretchable and printable. The stretchable electrode acquires intrinsic stretchability and improved interfacial adhesion with the active materials via a functionalized physically cross-linked organogel as a stretchable binder and separator. Intrinsically stretchable current collectors are fabricated in the form of nanocomposites consisting of a matrix with excellent barrier properties without swelling in organic electrolytes and nanostructure-controlled multimodal conductive fillers. Due to structural and materials freedoms, we successfully fabricate several types of stretchable lithium-ion battery that reliably operates under various stretch deformations with capacity and rate capability comparable with a nonstretchable battery over 2.5 mWh cm-2 at 0.5 C, even under high mass loading conditions over 10 mg cm-2, including stacked configuration, direct integration on both sides of a stretch fabric, and application of various electrode materials and electrolytes. Especially, our stretchable battery printed on a stretch fabric also exhibits high performance and stretch/long-term stabilities in the air even with wearing and pulling.

12.
ACS Nano ; 16(12): 20533-20544, 2022 12 27.
Artículo en Inglés | MEDLINE | ID: mdl-36475304

RESUMEN

As the turnaround time of diagnosis becomes important, there is an increasing demand for rapid, point-of-care testing (POCT) based on polymerase chain reaction (PCR), the most reliable diagnostic tool. Although optical components in real-time PCR (qPCR) have quickly become compact and economical, conventional PCR instruments still require bulky thermal systems, making it difficult to meet emerging needs. Photonic PCR, which utilizes photothermal nanomaterials as heating elements, is a promising platform for POCT as it reduces power consumption and process time. Here, we develop a photonic qPCR platform using hydrogel microparticles. Microparticles consisting of hydrogel matrixes containing photothermal nanomaterials and primers are dubbed photothermal primer-immobilized networks (pPINs). Reduced graphene oxide is selected as the most suitable photothermal nanomaterial to generate heat in pPIN due to its superior light-to-heat conversion efficiency. The photothermal reaction volume of 100 nL (predefined by the pPIN dimensions) provides fast heating and cooling rates of 22.0 ± 3.0 and 23.5 ± 2.6 °C s-1, respectively, enabling ultrafast qPCR within 5 min only with optical components. The microparticle-based photonic qPCR facilitates multiplex assays by loading multiple encoded pPIN microparticles in a single reaction. As a proof of concept, four-plex pPIN qPCR for bacterial discrimination are successfully demonstrated.


Asunto(s)
Micropartículas Derivadas de Células , Nanoestructuras , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Calor , Hidrogeles
13.
ACS Appl Mater Interfaces ; 13(5): 6257-6264, 2021 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-33508940

RESUMEN

With the continuous development of flexible and wearable thermoelectric generators (TEGs), high-performance materials and their integration into convenient wearable devices have to be considered. Herein, we have demonstrated highly aligned wet-spun carbon nanotube (CNT) fibers by optimizing the liquid crystalline (LC) phase via hydrochloric acid purification. The liquid crystalline phase facilitates better alignment of CNTs during fiber extrusion, resulting in the high power factor of 2619 µW m-1 K-2, which surpasses those of the dry-spun CNT yarns. A flexible all-carbon TEG was fabricated by stitching a single CNT fiber and doping selected segments into n-type by simple injection doping. The flexible TEG shows the maximum output power densities of 1.9 mW g-1 and 10.3 mW m-2 at ΔT = 30 K. Furthermore, the flexible TEG was developed into a prototype watch-strap TEG, demonstrating easy wearability and direct harvesting of body heat into electrical energy. Combining high-performance materials with scalable fabrication methods ensures the great potential for flexible/or wearable TEGs to be utilized as future power-conversion devices.

14.
ACS Nano ; 15(8): 13118-13128, 2021 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-34279909

RESUMEN

As power-conversion devices, flexible thermoelectrics that enable conformal contact with heat sources of arbitrary shape are attractive. However, the low performance of flexible thermoelectric materials, which does not exceed those of brittle inorganic counterparts, hampers their practical applications. Herein, we propose inorganic chalcogenide-nanostructured carbon nanotube (CNT) yarns with outstanding power factor at a low temperature using electrochemical deposition. The inorganic chalcogenide-nanostructured CNT yarns exhibit the power factors of 3425 and 2730 µW/(m·K2) at 298 K for the p- and n-type, respectively, which is higher than those of previously reported flexible TE materials. On the basis of excellent performance and geometry advantage of the nanostructured CNT yarn for modular design, all-CNT based thermoelectric generators have been easily fabricated, showing the maximum power densities of 24 and 380 mW/m2 at ΔT = 5 and 20 K, respectively. These results provide a promising strategy for the realization of high-performance flexible thermoelectric materials and devices for flexible/or wearable self-powering systems.

15.
ACS Appl Mater Interfaces ; 13(26): 30295-30305, 2021 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-34165969

RESUMEN

As viruses have been threatening global public health, fast diagnosis has been critical to effective disease management and control. Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) is now widely used as the gold standard for detecting viruses. Although a multiplex assay is essential for identifying virus types and subtypes, the poor multiplicity of RT-qPCR makes it laborious and time-consuming. In this paper, we describe the development of a multiplex RT-qPCR platform with hydrogel microparticles acting as independent reactors in a single reaction. To build target-specific particles, target-specific primers and probes are integrated into the particles in the form of noncovalent composites with boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs). The thermal release characteristics of DNA, primer, and probe from the composites of primer-BNNT and probe-CNT allow primer and probe to be stored in particles during particle production and to be delivered into the reaction. In addition, BNNT did not absorb but preserved the fluorescent signal, while CNT protected the fluorophore of the probe from the free radicals present during particle production. Bicompartmental primer-incorporated network (bcPIN) particles were designed to harness the distinctive properties of two nanomaterials. The bcPIN particles showed a high RT-qPCR efficiency of over 90% and effective suppression of non-specific reactions. 16-plex RT-qPCR has been achieved simply by recruiting differently coded bcPIN particles for each target. As a proof of concept, multiplex one-step RT-qPCR was successfully demonstrated with a simple reaction protocol.


Asunto(s)
Hidrogeles/química , Reacción en Cadena de la Polimerasa Multiplex/métodos , Nanotubos de Carbono/química , ARN Viral/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Compuestos de Boro/química , Coronavirus/química , Cartilla de ADN/química , ADN de Cadena Simple/química , Colorantes Fluorescentes/química , Grafito/química , Virus de la Influenza A/química , Virus de la Enfermedad de Newcastle/química , Prueba de Estudio Conceptual , ARN Viral/química , Virosis/diagnóstico
16.
ACS Appl Mater Interfaces ; 12(23): 26250-26257, 2020 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-32403922

RESUMEN

We report two organocompatible strategies to enhance the output performance of all-solution-processed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thermoelectric generators (TEGs): introducing an additive spray printing process and functionalized polymer interlayers to reduce the module resistance. The spray printing enabled the deposition of 1-µm-thick PEDOT:PSS layers with a high degree of design freedom, resulting in a significantly reduced sheet resistance of 16 Ω sq-1 that is closely related to the thermoelectric output performance. Also, by inserting an ultrathin silane-terminated polystyrene (PS) interlayer between the PEDOT:PSS thermoelectric layers and inkjet-printed Ag interconnects selectively, the contact resistivity extracted by the transmission line method was reduced from 6.02 × 10-2 to 2.77 × 10-2 Ω cm2. We found that the PS interlayers behaved as a thin tunneling layer, which facilitated the carrier injection from the inkjet-printed Ag electrodes into the PEDOT:PSS films by field emission with an effectively lowered energy barrier. The activation energy was also extracted using the Richardson equation, resulting in a reduction of 2.59 ± 0.04 meV after the PS treatment. Scalable plastic-compatible processability and selective interface engineering enabled to demonstrate the flexible 74-leg PEDOT:PSS TEGs exhibiting the open-circuit voltage of 9.21 mV and the output power of 2.23 nW at a temperature difference of 10 K.

17.
Nat Commun ; 11(1): 5948, 2020 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-33230141

RESUMEN

Softening of thermoelectric generators facilitates conformal contact with arbitrary-shaped heat sources, which offers an opportunity to realize self-powered wearable applications. However, existing wearable thermoelectric devices inevitably exhibit reduced thermoelectric conversion efficiency due to the parasitic heat loss in high-thermal-impedance polymer substrates and poor thermal contact arising from rigid interconnects. Here, we propose compliant thermoelectric generators with intrinsically stretchable interconnects and soft heat conductors that achieve high thermoelectric performance and unprecedented conformability simultaneously. The silver-nanowire-based soft electrodes interconnect bismuth-telluride-based thermoelectric legs, effectively absorbing strain energy, which allows our thermoelectric generators to conform perfectly to curved surfaces. Metal particles magnetically self-assembled in elastomeric substrates form soft heat conductors that significantly enhance the heat transfer to the thermoelectric legs, thereby maximizing energy conversion efficiency on three-dimensional heat sources. Moreover, automated additive manufacturing paves the way for realizing self-powered wearable applications comprising hundreds of thermoelectric legs with high customizability under ambient conditions.

18.
Nanoscale ; 11(36): 16919-16927, 2019 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-31490468

RESUMEN

With the increase in practical interest in flexible thermoelectric (TE) generators, the demand for high-performance alternatives to brittle TE materials is growing. Herein, we have demonstrated wet-spun CNT fibers with high TE performance by systematically controlling the longitudinal carrier mobility without a significant change in the carrier concentration. The carrier mobility optimized by CNT alignment increases the electrical conductivity without decreasing the thermopower, thus improving the power factor. On further adjusting the charge carriers via mild annealing, the CNT fibers exhibit a high power factor of 432 µW m-1 K-2. Based on the excellent TE performance and shape advantages for modular design of the CNT fiber, the all-carbon based flexible TE generator without an additional metal electrode has been fabricated. The flexible TE generator based on 40 pairs of p- and n-type CNT fibers shows the maximum power density of 15.4 and 259 µW g-1 at temperature differences (ΔT) of 5 and 20 K, respectively, currently one of the highest values reported for TE generators based on flexible materials. The strategy proposed here can improve the performance of flexible TE fibers by optimizing the carrier mobility without a change in the carrier concentration, and shows great potential for flexible TE generators.

19.
Eye (Lond) ; 33(11): 1707-1714, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31089238

RESUMEN

OBJECTIVES: To compare and evaluate the characteristics of hypertensive choroidopathy with serous retinal detachment in preeclampsia and malignant hypertension (HTN) and explore choroidal ischemia as a pathogenesis using multimodal imaging. METHODS: A retrospective multicenter case series. Medical charts were reviewed. Clinical characteristics and multimodal imaging, including optical coherence tomography (OCT) and OCT angiography (OCTA), were evaluated. RESULTS: Fifty-three eyes of 29 preeclampsia patients and 45 eyes of 24 HTN patients were included. There were no differences in age, follow-up duration, baseline visual acuity, central macular thickness (CMT), or subfoveal choroidal thickness (CT) between the two groups. Blood pressure parameters, including systolic blood pressure, diastolic blood pressure, and pulse rate, were significantly higher in the HTN group. After serous retinal detachment resolved, both CMT (p < 0.001) and CT (p = 0.003) decreased more in the preeclampsia group. Hypertensive retinopathy features, including hemorrhage, exudates, cotton-wool spots, and optic disc edema, were predominantly found in the HTN group (p = 0.001). Final visual acuity was better in the preeclampsia group than in the HTN group (p = 0.048). Poor visual prognostic factors included the presence of retinopathy features (p = 0.005) and retinal detachment in the macula (p = 0.017). CONCLUSION: Choroidal circulation may be affected earlier than retinal circulation by elevated blood pressure, presumably because of anatomical differences and autoregulatory mechanisms in the retinal vasculature. Serous retinal detachment with hypertensive choroidopathy presented with choroidal thickening that decreased after resolution, but the residual flow defects observed in the choriocapillaris on OCTA confirmed the long-hypothesized notion that ischemia is a mechanism underlying hypertensive choroidopathy.


Asunto(s)
Enfermedades de la Coroides/etiología , Coroides/irrigación sanguínea , Hipertensión Maligna/complicaciones , Preeclampsia/etiología , Desprendimiento de Retina/etiología , Adulto , Presión Sanguínea/fisiología , Enfermedades de la Coroides/diagnóstico por imagen , Enfermedades de la Coroides/fisiopatología , Femenino , Angiografía con Fluoresceína , Estudios de Seguimiento , Frecuencia Cardíaca/fisiología , Humanos , Imagen Multimodal , Preeclampsia/diagnóstico por imagen , Preeclampsia/fisiopatología , Embarazo , Desprendimiento de Retina/diagnóstico por imagen , Desprendimiento de Retina/fisiopatología , Estudios Retrospectivos , Tomografía de Coherencia Óptica , Agudeza Visual/fisiología
20.
ACS Appl Mater Interfaces ; 11(40): 37043-37050, 2019 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-31518103

RESUMEN

As practical interest in stretchable electronics increases for future applications in wearables, healthcare, and robotics, the demand for electrical interconnects with high electrical conductivity, durability, printability, and adhesion is growing. Despite the high electrical conductivity and stretchability of most previous interconnects, they lack stable conductivity against strain and adhesion to stretchable substrates, leading to a limitation for their practical applications. Herein, we propose a stretchable conductive adhesive consisting of silver particles with carbon nanotube as an auxiliary filler in silicone adhesives. The conductive adhesive exhibits a high initial conductivity of 6450 S cm-1. They show little change in conductivity over 3000 stretching cycles at 50% strain, currently the highest stability reported for elastic conductors. Based on strong adhesion to stretchable substrates, the gel-free, dry adhesives printed on an elastic bandage for electrocardiography monitoring exhibit an extremely stable performance upon movement of the subject, even after several cycles of detachment-reattachment and machine washing.


Asunto(s)
Adhesivos/química , Conductividad Eléctrica , Electrónica , Impresión , Textiles , Electrodos , Siliconas/química
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