Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
1.
Am J Pathol ; 193(7): 866-882, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37024046

RESUMEN

The disease severity of coronavirus disease 2019 (COVID-19) varies considerably from asymptomatic to serious, with fatal complications associated with dysregulation of innate and adaptive immunity. Lymphoid depletion in lymphoid tissues and lymphocytopenia have both been associated with poor disease outcomes in patients with COVID-19, but the mechanisms involved remain elusive. In this study, human angiotensin-converting enzyme 2 (hACE2) transgenic mouse models susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were used to investigate the characteristics and determinants of lethality associated with the lymphoid depletion observed in SARS-CoV-2 infection. The lethality of Wuhan SARS-CoV-2 infection in K18-hACE2 mice was characterized by severe lymphoid depletion and apoptosis in lymphoid tissues related to fatal neuroinvasion. The lymphoid depletion was associated with a decreased number of antigen-presenting cells (APCs) and their suppressed functionality below basal levels. Lymphoid depletion with reduced APC function was a specific feature observed in SARS-CoV-2 infection but not in influenza A infection and had the greatest prognostic value for disease severity in murine COVID-19. Comparison of transgenic mouse models resistant and susceptible to SARS-CoV-2 infection revealed that suppressed APC function could be determined by the hACE2 expression pattern and interferon-related signaling. Thus, we demonstrated that lymphoid depletion associated with suppressed APC function characterizes the lethality of COVID-19 mouse models. Our data also suggest a potential therapeutic approach to prevent the severe progression of COVID-19 by enhancing APC functionality.


Asunto(s)
COVID-19 , Ratones , Humanos , Animales , SARS-CoV-2/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Ratones Transgénicos , Susceptibilidad a Enfermedades , Células Presentadoras de Antígenos , Modelos Animales de Enfermedad , Pulmón/metabolismo
2.
Proc Natl Acad Sci U S A ; 113(39): 10779-84, 2016 09 27.
Artículo en Inglés | MEDLINE | ID: mdl-27621444

RESUMEN

Lithium metal is a promising anode material for Li-ion batteries due to its high theoretical specific capacity and low potential. The growth of dendrites is a major barrier to the development of high capacity, rechargeable Li batteries with lithium metal anodes, and hence, significant efforts have been undertaken to develop new electrolytes and separator materials that can prevent this process or promote smooth deposits at the anode. Central to these goals, and to the task of understanding the conditions that initiate and propagate dendrite growth, is the development of analytical and nondestructive techniques that can be applied in situ to functioning batteries. MRI has recently been demonstrated to provide noninvasive imaging methodology that can detect and localize microstructure buildup. However, until now, monitoring dendrite growth by MRI has been limited to observing the relatively insensitive metal nucleus directly, thus restricting the temporal and spatial resolution and requiring special hardware and acquisition modes. Here, we present an alternative approach to detect a broad class of metallic dendrite growth via the dendrites' indirect effects on the surrounding electrolyte, allowing for the application of fast 3D (1)H MRI experiments with high resolution. We use these experiments to reconstruct 3D images of growing Li dendrites from MRI, revealing details about the growth rate and fractal behavior. Radiofrequency and static magnetic field calculations are used alongside the images to quantify the amount of the growing structures.

3.
J Am Chem Soc ; 137(48): 15209-16, 2015 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-26524078

RESUMEN

Lithium dendrite growth in lithium ion and lithium rechargeable batteries is associated with severe safety concerns. To overcome these problems, a fundamental understanding of the growth mechanism of dendrites under working conditions is needed. In this work, in situ (7)Li magnetic resonance (MRI) is performed on both the electrolyte and lithium metal electrodes in symmetric lithium cells, allowing the behavior of the electrolyte concentration gradient to be studied and correlated with the type and rate of microstructure growth on the Li metal electrode. For this purpose, chemical shift (CS) imaging of the metal electrodes is a particularly sensitive diagnostic method, enabling a clear distinction to be made between different types of microstructural growth occurring at the electrode surface and the eventual dendrite growth between the electrodes. The CS imaging shows that mossy types of microstructure grow close to the surface of the anode from the beginning of charge in every cell studied, while dendritic growth is triggered much later. Simple metrics have been developed to interpret the MRI data sets and to compare results from a series of cells charged at different current densities. The results show that at high charge rates, there is a strong correlation between the onset time of dendrite growth and the local depletion of the electrolyte at the surface of the electrode observed both experimentally and predicted theoretical (via the Sand's time model). A separate mechanism of dendrite growth is observed at low currents, which is not governed by salt depletion in the bulk liquid electrolyte. The MRI approach presented here allows the rate and nature of a process that occurs in the solid electrode to be correlated with the concentrations of components in the electrolyte.

4.
Nat Mater ; 11(4): 311-5, 2012 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-22327745

RESUMEN

There is an ever-increasing need for advanced batteries for portable electronics, to power electric vehicles and to facilitate the distribution and storage of energy derived from renewable energy sources. The increasing demands on batteries and other electrochemical devices have spurred research into the development of new electrode materials that could lead to better performance and lower cost (increased capacity, stability and cycle life, and safety). These developments have, in turn, given rise to a vigorous search for the development of robust and reliable diagnostic tools to monitor and analyse battery performance, where possible, in situ. Yet, a proven, convenient and non-invasive technology, with an ability to image in three dimensions the chemical changes that occur inside a full battery as it cycles, has yet to emerge. Here we demonstrate techniques based on magnetic resonance imaging, which enable a completely non-invasive visualization and characterization of the changes that occur on battery electrodes and in the electrolyte. The current application focuses on lithium-metal batteries and the observation of electrode microstructure build-up as a result of charging. The methods developed here will be highly valuable in the quest for enhanced battery performance and in the evaluation of other electrochemical devices.

5.
Solid State Nucl Magn Reson ; 42: 62-70, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22381594

RESUMEN

The application of in situ nuclear magnetic resonance (NMR) to investigate batteries in real time (i.e., as they are cycling) provides fruitful insight into the electrochemical structural changes that occur in the battery. A major challenge for in situ static NMR spectroscopy of a battery is, however, to separate the resonances from the different components. Many resonances overlap and are broadened since spectra are acquired, to date, in static mode. Spectral analysis is also complicated by bulk magnetic susceptibility (BMS) effects. Here we describe some of the BMS effects that arise in lithium ion battery (LIB) materials and provide an outline of some of the practical considerations associated with the application of in situ NMR spectroscopy to study structural changes in energy materials.


Asunto(s)
Suministros de Energía Eléctrica , Electrodos , Litio/química , Espectroscopía de Resonancia Magnética/métodos , Ensayo de Materiales/métodos , Transferencia de Energía , Diseño de Equipo , Iones , Campos Magnéticos
6.
Nat Nanotechnol ; 17(3): 269-277, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-34949775

RESUMEN

Solid-state sodium (Na) batteries have received extensive attention as a promising alternative to room-temperature liquid electrolyte Na-ion batteries and high-temperature liquid electrode Na-S batteries because of safety concerns. However, the major issues for solid-state Na batteries are a high interfacial resistance between solid electrolytes and electrodes, and Na dendrite growth. Here we report that a yttria-stabilized zirconia (YSZ)-enhanced beta-alumina solid electrolyte (YSZ@BASE) has an extremely low interface impedance of 3.6 Ω cm2 with the Na metal anode at 80 °C, and also exhibits an extremely high critical current density of ~7.0 mA cm-2 compared with those of other Li- and Na-ion solid electrolytes reported so far. With a trace amount of eutectic NaFSI-KFSI molten salt at the electrolyte/cathode interface, a quasi-solid-state Na/YSZ@BASE/NaNi0.45Cu0.05Mn0.4Ti0.1O2 full cell achieves a high capacity of 110 mAh g-1 with a Coulombic efficiency >99.99% and retains 73% of the cell capacity over 500 cycles at 4C and 80 °C. Extensive characterizations and theoretical calculations prove that the stable ß-NaAlO2-rich solid-electrolyte interphase and strong YSZ support matrix play a critical role in suppressing the Na dendrite as they maintain robust interfacial contacts, lower electronic conduction and prevent the continual reduction of BASE through oxygen-ion compensation.

7.
ACS Appl Mater Interfaces ; 12(38): 42763-42772, 2020 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-32852196

RESUMEN

Zinc-based batteries have attracted extensive attention in recent years, due to high safety, high capacities, environmental friendliness, and low cost compared to lithium-ion batteries. However, the zinc anode suffers primarily from dendrite formation as a mode of failure in the mildly acidic system. Herein, we report on electrochemically deposited zinc (ED Zn) and copper-zinc (brass) alloy anodes, which are critically compared with a standard commercial zinc foil. The film electrodes are of commercially relevant thicknesses (21 and 25 µM). The electrodeposited zinc-based anodes exhibit low electrode polarization (∼0.025 V) and stable cycling performance in 50 cycle consecutive experiments from 0.26 to 10 mA cm-2 compared to commercial Zn foil. Coulombic efficiencies at 1 mA cm-2 were over 98% for the electrodeposited zinc-based materials and were maintained for over 100 cycles. Furthermore, full cells with an electrodeposited Zn/brass anode, electrolytic manganese dioxide (EMD) cathode, in 1 M ZnSO4 + 0.1 M MnSO4 delivered capacities of 96.3 and 163 mAh g-1, respectively, at 100 mA g-1 compared to 92.1 mAh g-1 for commercial Zn. The electrodeposited zinc-based anodes also show better rate capability, delivering full cell capacities of 35.9 and 47.5 mAh g-1 at a high current of up to 3 A g-1. Lastly, the electrodeposited zinc-based anodes show enhanced capacity for up to 100 cycles at 100 mA g-1, making them viable anodes for commercial use.

8.
Anticancer Res ; 29(1): 355-62, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19331173

RESUMEN

Resveratrol, a grape polyphenol, is thought to have anti-inflammatory, cardioprotective, and cancer preventive properties. However, the mechanisms by which resveratrol might produce these effects are not clearly defined. A study was performed on whether resveratrol could prevent tumor cells from adhering to endothelial cells, which is an essential step during tumor metastasis. Phorbol 12-myristate 13-acetate (PMA) induced human fibrosarcoma HT1080 cells to adhere to endothelial ECV304 cells. Resveratrol inhibited PMA-induced HT1080 cells adhesion in a dose-dependent manner. To further study the mechanisms of this resveratrol-mediated blockade of tumor cell adhesion, the expression of the cell adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin were examined. PMA induced ICAM-1 expression in HT1080 cells. In contrast, the expression of VCAM-1 and E-selectin were not altered by PMA treatment. The increase in tumor cell adhesion to endothelial cells following PMA treatment was partially inhibited by ICAM-1 siRNA or neutralizing antibodies. Resveratrol reduced the PMA-induced ICAM-1 expression in HT1080 cells as determined by RT-PCR, flow cytometry and ELISA. As the induction of ICAM-1 requires activation of the transcription factor NF-kappaB, the effects of resveratrol on the activation of this factor in HT1080 cells was also investigated. Resveratrol inhibited the PMA-induced NF-kappaB activation and NF-kappaB-dependent luciferase activity. These results suggest that resveratrol may exert an antimetastatic effect by inhibiting NF-kappaB activation and ICAM-1 expression, leading to suppression of tumor cell adhesion to endothelial cells.


Asunto(s)
Adhesión Celular/efectos de los fármacos , Células Endoteliales/efectos de los fármacos , Fibrosarcoma/patología , Molécula 1 de Adhesión Intercelular/biosíntesis , Estilbenos/farmacología , Relación Dosis-Respuesta a Droga , Células Endoteliales/metabolismo , Células Endoteliales/patología , Fibrosarcoma/tratamiento farmacológico , Fibrosarcoma/metabolismo , Humanos , Molécula 1 de Adhesión Intercelular/genética , FN-kappa B/antagonistas & inhibidores , FN-kappa B/metabolismo , ARN Interferente Pequeño/genética , Resveratrol , Acetato de Tetradecanoilforbol/farmacología , Transfección
9.
ACS Appl Mater Interfaces ; 11(41): 37524-37530, 2019 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-31525016

RESUMEN

Recently, mild aqueous rechargeable Zn-MnO2 batteries have attracted increasing interest for energy storage due to the low cost of Zn and Mn resources, high safety, and environmental benignity. Extensive types of MnO2 have been proposed as the cathodes in the literature, but the different reported performance and lack of a thorough understanding of reactions in MnO2 cathodes greatly hinder the practical applications of mild aqueous Zn-MnO2 batteries. Here, we revealed the correlation between the reaction mechanisms and the used electrolytes for the mild aqueous zinc-electrolytic manganese dioxide (EMD) batteries. In optimal Zn(TFSI)2-based electrolyte, the EMD cathode exhibits a mixed diffusion-controlled conversion reaction between EMD and H+ and diffusion-free "pseudocapacitance"-like reactions. This mechanism enables excellent cycling stability of an EMD cathode over 5000 cycles with a capacity retention of 94.6%. This study provides a useful insight into developing reversible MnO2 cathodes through rational control of reaction mechanisms for high performance mild aqueous Zn-MnO2 batteries.

10.
J Cell Biochem ; 104(3): 1102-12, 2008 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-18247343

RESUMEN

There is a strong correlation between the overexpression of urokinase-type plasminogen activator receptor (uPAR) and gastric cancer invasion. This study examined the effect of phospholipid lysophosphatidic acid (LPA) on uPAR expression in human gastric cancer AGS cells and the underlying signal transduction pathways. Treating human gastric AGS cells with LPA induced the expression of uPAR mRNA and promoter activity in both a time- and dose-dependent manner. Small interfering RNA targeting for LPA receptors, dominant negative Rho-family GTPase (RhoA, Rac1, and Cdc42) and an expression vector encoding a mutated c-jun (TAM67) partially blocked the LPA-induced uPAR expression. Site-directed mutagenesis and electrophoretic mobility shift studies showed that the transcription factors activation protein-1 (AP-1) and nuclear factor (NF)-kappaB are essential for the LPA-induced uPAR transcription. In addition, AGS cells treated with LPA showed enhanced invasion, which was partially abrogated by the uPAR-neutralizing antibodies and inhibitors of Rho kinase, JNK, and NF-kappaB. This suggests that LPA induces uPAR expression through the LPA receptors, Rho-family GTPase, JNK, AP-1 and NF-kappaB signaling pathways, which in turn stimulates the cell invasiveness of human gastric cancer AGS cells.


Asunto(s)
Regulación Neoplásica de la Expresión Génica , Lisofosfolípidos/farmacología , Receptores de Superficie Celular/metabolismo , Neoplasias Gástricas/metabolismo , Regulación hacia Arriba , Línea Celular Tumoral , Movimiento Celular , Núcleo Celular/metabolismo , Colágeno/metabolismo , Combinación de Medicamentos , Humanos , Laminina/metabolismo , FN-kappa B/metabolismo , Invasividad Neoplásica , Regiones Promotoras Genéticas , Proteoglicanos/metabolismo , Receptores del Activador de Plasminógeno Tipo Uroquinasa , Factor de Transcripción AP-1/metabolismo
11.
ACS Omega ; 3(11): 15702-15708, 2018 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-31458224

RESUMEN

The Na-ß-alumina battery (NBB) is one of the most promising energy storage technologies for integrating renewable energy resources into the grid. In the family of NBBs, Na-NiCl2 battery has been extensively studied during the past decade because it has a lower operating temperature, better safety, and good battery performance. One of the major issues with the Na-NiCl2 battery is material cost, which is primarily from Ni metal in the battery cathode. As an alternative, Zn is much cheaper than Ni, and replacing Ni with Zn in the cathode can significantly reduce the cost. In this work, we investigate the performance and reaction mechanism for a Na-ZnCl2 battery at 190 °C. Two-step reversible reactions are identified. During the first step of charging, NaCl reacts with Zn to produce a ribbon-type Na2ZnCl4 layer. This layer is formed at the NaCl-Zn interface rather than covering the surface of the Zn particles, which leads to an excellent cell rate capability. During the second step, the produced Na2ZnCl4 is gradually consumed to form ZnCl2 on the surface of Zn particles. The formed ZnCl2 covers most of the surface area of the Zn particles and shows a limited rate capability compared to that of the first step. We conclude that this limited performance of the second step is due to the passivation of Zn particles by ZnCl2, which blocks the electron pathway of the NaCl-Zn cathodes.

12.
ACS Appl Mater Interfaces ; 9(13): 11609-11614, 2017 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-28300391

RESUMEN

Stationary electric energy storage devices (rechargeable batteries) have gained increasing prominence due to great market needs, such as smoothing the fluctuation of renewable energy resources and supporting the reliability of the electric grid. With regard to raw materials availability, sodium-based batteries are better positioned than lithium batteries due to the abundant resource of sodium in Earth's crust. However, the sodium-nickel chloride (Na-NiCl2) battery, one of the most attractive stationary battery technologies, is hindered from further market penetration by its high material cost (Ni cost) and fast material degradation at its high operating temperature. Here, we demonstrate the design of a core-shell microarchitecture, nickel-coated graphite, with a graphite core to maintain electrochemically active surface area and structural integrity of the electron percolation pathway while using 40% less Ni than conventional Na-NiCl2 batteries. An initial energy density of 133 Wh/kg (at ∼C/4) and energy efficiency of 94% are achieved at an intermediate temperature of 190 °C.

13.
Nat Commun ; 7: 10683, 2016 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-26864635

RESUMEN

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium-nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg(-1), higher than that of conventional tubular sodium-nickel chloride batteries (280 °C), is obtained for planar sodium-nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium-nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs.

14.
Chem Commun (Camb) ; 51(2): 266-8, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-24898258

RESUMEN

The electrodeposition of metallic lithium is a major cause of failure in lithium batteries. The 3D microstructure of electrodeposited lithium 'moss' in liquid electrolytes has been characterised at sub-micron resolution for the first time. Using synchrotron X-ray phase contrast imaging we distinguish mossy metallic lithium microstructures from high surface area lithium salt formations by their contrasting X-ray attenuation.


Asunto(s)
Galvanoplastia , Imagenología Tridimensional , Litio/química , Galvanoplastia/métodos , Imagenología Tridimensional/métodos , Sincrotrones , Rayos X
15.
J Magn Reson ; 245: 143-9, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25036296

RESUMEN

While experiments on metals have been performed since the early days of NMR (and DNP), the use of bulk metal is normally avoided. Instead, often powders have been used in combination with low fields, so that skin depth effects could be neglected. Another complicating factor of acquiring NMR spectra or MRI images of bulk metal is the strong signal dependence on the orientation between the sample and the radio frequency (rf) coil, leading to non-intuitive image distortions and inaccurate quantification. Such factors are particularly important for NMR and MRI of batteries and other electrochemical devices. Here, we show results from a systematic study combining rf field calculations with experimental MRI of (7)Li metal to visualize skin depth effects directly and to analyze the rf field orientation effect on MRI of bulk metal. It is shown that a certain degree of selectivity can be achieved for particular faces of the metal, simply based on the orientation of the sample. By combining rf field calculations with bulk magnetic susceptibility calculations accurate NMR spectra can be obtained from first principles. Such analyses will become valuable in many applications involving battery systems, but also metals, in general.

16.
Biol Pharm Bull ; 30(12): 2290-3, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18057714

RESUMEN

Licochalcones have a variety of biological properties including anti-tumor, anti-parasitic and anti-bacterial activities. Recently, a new retrochalcone (licochalcone E, Lico-E) was isolated from the roots of Glycyrrhiza inflata (Chem. Pharm. Bull., 53, 2005, Yoon et al.) by cytotoxicity-guided fractionation. This study examined whether or not Lico-E-induced endothelial cell death occurs through apoptosis, and investigated molecular mechanisms involved in this process. Lico-E was found to suppress ECV304 cell growth and induce apoptosis. The induction of apoptosis by Lico-E was confirmed by the ladder-patterned DNA fragmentation, the presence of cleaved and condensed nuclear chromatin and the increased number of annexin V-positive cells. Lico-E could effectively inhibit the constitutive NF-kappaB activation, as revealed by the electrophoretic mobility shift assay and NF-kappaB-dependent luciferase reporter study. In addition, the Lico-E treatment caused a change in the Bax/Bcl-2 ratio that favored apoptosis. These results suggest that Lico-E induces endothelial cell apoptosis by modulating NF-kappaB and the Bcl-2 family.


Asunto(s)
Inhibidores de la Angiogénesis , Apoptosis/efectos de los fármacos , Chalconas/farmacología , Genes bcl-2/fisiología , FN-kappa B/fisiología , Bencimidazoles , Western Blotting , Línea Celular , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Supervivencia Celular/efectos de los fármacos , Fragmentación del ADN/efectos de los fármacos , Ensayo de Cambio de Movilidad Electroforética , Células Endoteliales/efectos de los fármacos , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Genes bcl-2/genética , Humanos , FN-kappa B/genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA