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1.
Nat Immunol ; 16(1): 57-63, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25521685

RESUMEN

Tuberculosis is a disease of the lung, and efficient transmission is dependent on the generation of a lesion in the lung, which results in a bacterium-laden cough. Mycobacterium tuberculosis (Mtb) is able to manipulate both the innate and acquired immune response of the host. This manipulation results in an effective CD4(+) T cell response that limits disease throughout the body but can also promote the development of progressively destructive lesions in the lung. In this way Mtb infection can result in an ambulatory individual who has a lesion in the lung capable of transmitting Mtb. The inflammatory environment within the lung lesion is manipulated by Mtb throughout infection and can limit the expression of acquired immunity by a variety of pathways.


Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Mycobacterium tuberculosis/inmunología , Tuberculosis/inmunología , Inmunidad Adaptativa/inmunología , Animales , Modelos Animales de Enfermedad , Humanos , Inmunidad Innata/inmunología , Tuberculosis/transmisión
2.
EMBO J ; 40(3): e106501, 2021 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-33270927

RESUMEN

Interferon-induced transmembrane proteins (IFITMs) restrict infections by many viruses, but a subset of IFITMs enhance infections by specific coronaviruses through currently unknown mechanisms. We show that SARS-CoV-2 Spike-pseudotyped virus and genuine SARS-CoV-2 infections are generally restricted by human and mouse IFITM1, IFITM2, and IFITM3, using gain- and loss-of-function approaches. Mechanistically, SARS-CoV-2 restriction occurred independently of IFITM3 S-palmitoylation, indicating a restrictive capacity distinct from reported inhibition of other viruses. In contrast, the IFITM3 amphipathic helix and its amphipathic properties were required for virus restriction. Mutation of residues within the IFITM3 endocytosis-promoting YxxФ motif converted human IFITM3 into an enhancer of SARS-CoV-2 infection, and cell-to-cell fusion assays confirmed the ability of endocytic mutants to enhance Spike-mediated fusion with the plasma membrane. Overexpression of TMPRSS2, which increases plasma membrane fusion versus endosome fusion of SARS-CoV-2, attenuated IFITM3 restriction and converted amphipathic helix mutants into infection enhancers. In sum, we uncover new pro- and anti-viral mechanisms of IFITM3, with clear distinctions drawn between enhancement of viral infection at the plasma membrane and amphipathicity-based mechanisms used for endosomal SARS-CoV-2 restriction.


Asunto(s)
Antígenos de Diferenciación/genética , COVID-19/genética , Proteínas de la Membrana/genética , Proteínas de Unión al ARN/genética , SARS-CoV-2 , Enzima Convertidora de Angiotensina 2/genética , Animales , Línea Celular , Chlorocebus aethiops , Humanos , Ratones , Mutación , SARS-CoV-2/fisiología , Serina Endopeptidasas , Internalización del Virus
3.
PLoS Pathog ; 19(8): e1011596, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37603565

RESUMEN

SARS-CoV-2 (CoV2) infected, asymptomatic individuals are an important contributor to COVID transmission. CoV2-specific immunoglobulin (Ig)-as generated by the immune system following infection or vaccination-has helped limit CoV2 transmission from asymptomatic individuals to susceptible populations (e.g. elderly). Here, we describe the relationships between COVID incidence and CoV2 lineage, viral load, saliva Ig levels (CoV2-specific IgM, IgA and IgG), and ACE2 binding inhibition capacity in asymptomatic individuals between January 2021 and May 2022. These data were generated as part of a large university COVID monitoring program in Ohio, United States of America, and demonstrate that COVID incidence among asymptomatic individuals occurred in waves which mirrored those in surrounding regions, with saliva CoV2 viral loads becoming progressively higher in our community until vaccine mandates were established. Among the unvaccinated, infection with each CoV2 lineage (pre-Omicron) resulted in saliva Spike-specific IgM, IgA, and IgG responses, the latter increasing significantly post-infection and being more pronounced than N-specific IgG responses. Vaccination resulted in significantly higher Spike-specific IgG levels compared to unvaccinated infected individuals, and uninfected vaccinees' saliva was more capable of inhibiting Spike function. Vaccinees with breakthrough Delta infections had Spike-specific IgG levels comparable to those of uninfected vaccinees; however, their ability to inhibit Spike binding was diminished. These data are consistent with COVID vaccines having achieved hoped-for effects in our community, including the generation of mucosal antibodies that inhibit Spike and lower community viral loads, and suggest breakthrough Delta infections were not due to an absence of vaccine-elicited Ig, but instead limited Spike binding activity in the face of high community viral loads.


Asunto(s)
Formación de Anticuerpos , COVID-19 , Anciano , Humanos , COVID-19/epidemiología , SARS-CoV-2 , Saliva , Universidades , Infección Irruptiva , Inmunoglobulina A , Inmunoglobulina G , Inmunoglobulina M
4.
Proc Natl Acad Sci U S A ; 119(21): e2202012119, 2022 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-35588457

RESUMEN

Severe acute respiratory syndrome coronavirus 2 (SARS­CoV-2) is a worldwide health concern, and new treatment strategies are needed. Targeting inflammatory innate immunity pathways holds therapeutic promise, but effective molecular targets remain elusive. Here, we show that human caspase-4 (CASP4) and its mouse homolog, caspase-11 (CASP11), are up-regulated in SARS­CoV-2 infections and that CASP4 expression correlates with severity of SARS­CoV-2 infection in humans. SARS­CoV-2­infected Casp11−/− mice were protected from severe weight loss and lung pathology, including blood vessel damage, compared to wild-type (WT) mice and mice lacking the caspase downstream effector gasdermin-D (Gsdmd−/−). Notably, viral titers were similar regardless of CASP11 knockout. Global transcriptomics of SARS­CoV-2­infected WT, Casp11−/−, and Gsdmd−/− lungs identified restrained expression of inflammatory molecules and altered neutrophil gene signatures in Casp11−/− mice. We confirmed that protein levels of inflammatory mediators interleukin (IL)-1ß, IL-6, and CXCL1, as well as neutrophil functions, were reduced in Casp11−/− lungs. Additionally, Casp11−/− lungs accumulated less von Willebrand factor, a marker for endothelial damage, but expressed more Kruppel-Like Factor 2, a transcription factor that maintains vascular integrity. Overall, our results demonstrate that CASP4/11 promotes detrimental SARS­CoV-2­induced inflammation and coagulopathy, largely independently of GSDMD, identifying CASP4/11 as a promising drug target for treatment and prevention of severe COVID-19.


Asunto(s)
COVID-19 , Caspasas Iniciadoras/metabolismo , SARS-CoV-2 , Tromboinflamación , Animales , COVID-19/enzimología , COVID-19/patología , Caspasas Iniciadoras/genética , Progresión de la Enfermedad , Humanos , Pulmón/patología , Ratones , Ratones Noqueados , Índice de Severidad de la Enfermedad , Tromboinflamación/enzimología , Tromboinflamación/genética
5.
J Am Chem Soc ; 146(26): 17613-17617, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38885442

RESUMEN

Synthesis of high-entropy oxide (HEO) nanocrystals has focused on increasing the temperature in the entropy term (T(ΔS)) to overcome the enthalpy term. However, these high temperatures lead to large, polydisperse nanocrystals. In this work, we leverage the low solubility product (Ksp) of metal oxides and optimize the Lewis-acid-catalyzed esterification reaction for equal rate production of the cation monomers to synthesize HEO nanocrystals at low temperatures, producing the smallest (<4 nm) and most monodisperse (<15% size dispersity) HEOs to date. We apply these HEO nanocrystals as electrocatalysts, exhibiting promising activity toward the oxygen evolution reaction in alkaline media, with an overpotential of 345 mV at 10 mA/cm2.

6.
PLoS Pathog ; 18(3): e1010093, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-35325013

RESUMEN

Mycobacterium tuberculosis (Mtb) and SARS-CoV-2 (CoV2) are the leading causes of death due to infectious disease. Although Mtb and CoV2 both cause serious and sometimes fatal respiratory infections, the effect of Mtb infection and its associated immune response on secondary infection with CoV2 is unknown. To address this question we applied two mouse models of COVID19, using mice which were chronically infected with Mtb. In both model systems, Mtb-infected mice were resistant to the pathological consequences of secondary CoV2 infection, and CoV2 infection did not affect Mtb burdens. Single cell RNA sequencing of coinfected and monoinfected lungs demonstrated the resistance of Mtb-infected mice is associated with expansion of T and B cell subsets upon viral challenge. Collectively, these data demonstrate that Mtb infection conditions the lung environment in a manner that is not conducive to CoV2 survival.


Asunto(s)
COVID-19 , Coinfección , Mycobacterium tuberculosis , Enfermedad Aguda , Animales , Ratones , Ratones Endogámicos C57BL , SARS-CoV-2
7.
Chemistry ; : e202401637, 2024 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-38837442

RESUMEN

We propose silver oxide as a cost-effective and sustainable alternative to noble metals for the catalytic reduction of nitroaromatic compounds.  In the present investigation, we have adopted a facile and green synthetic route for the synthesis of silver oxide nanostructures. The prepared nanostructures were found to have crystallized in the cuprite phase and exhibited absorbance over the entire visible range of the electromagnetic spectrum. The catalytic potential of the silver oxide was evaluated by following the kinetics of nitrophenol reduction under ambient conditions and is observed to follow pseudo-first order kinetics with the apparent rate constant kapp = 4.24 x 10-3 s-1 at minimum concentration of the catalyst. We attribute the observed catalytic activity to the freshly generated catalytic surface featuring a partially reduced form of silver oxide. The findings highlight the efficacy of silver oxide in mitigating the environmental pollution originating from the recalcitrant nitroarenes.

8.
J Am Chem Soc ; 145(31): 17406-17419, 2023 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-37525439

RESUMEN

While certain ternary spinel oxides have been well-explored with colloidal nanochemistry, notably the ferrite spinel family, ternary manganese (Mn)-based spinel oxides have not been tamed. A key composition is cobalt (Co)-Mn oxide (CMO) spinel, CoxMn3-xO4, that, despite exemplary performance in multiple electrochemical applications, has few reports in the colloidal literature. Of these reports, most show aggregated and polydisperse products. Here, we describe a synthetic method for small, colloidally stable CMO spinel nanocrystals with tunable composition and low dispersity. By reacting 2+ metal-acetylacetonate (M(acac)2) precursors in an amine solvent under an oxidizing environment, we developed a pathway that avoids the highly reducing conditions of typical colloidal synthesis reactions; these reducing conditions typically push the system toward a monoxide impurity phase. Through surface chemistry studies, we identify organic byproducts and their formation mechanism, enabling us to engineer the surface and obtain colloidally stable nanocrystals with low organic loading. We report a CMO/carbon composite with low organic contents that performs the oxygen reduction reaction (ORR) with a half-wave potential (E1/2) of 0.87 V vs RHE in 1.0 M potassium hydroxide at 1600 rpm, rivaling previous reports for the highest activity of this material in ORR electrocatalysis. We extend the general applicability of this procedure to other Mn-based spinel nanocrystals such as Zn-Mn-O, Fe-Mn-O, Ni-Mn-O, and Cu-Mn-O. Finally, we show the scalability of this method by producing inorganic nanocrystals at the gram scale.

9.
Nat Mater ; 21(5): 518-525, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35422509

RESUMEN

Spontaneous hierarchical self-organization of nanometre-scale subunits into higher-level complex structures is ubiquitous in nature. The creation of synthetic nanomaterials that mimic the self-organization of complex superstructures commonly seen in biomolecules has proved challenging due to the lack of biomolecule-like building blocks that feature versatile, programmable interactions to render structural complexity. In this study, highly aligned structures are obtained from an organic-inorganic mesophase composed of monodisperse Cd37S18 magic-size cluster building blocks. Impressively, structural alignment spans over six orders of magnitude in length scale: nanoscale magic-size clusters arrange into a hexagonal geometry organized inside micrometre-sized filaments; self-assembly of these filaments leads to fibres that then organize into uniform arrays of centimetre-scale bands with well-defined surface periodicity. Enhanced patterning can be achieved by controlling processing conditions, resulting in bullseye and 'zigzag' stacking patterns with periodicity in two directions. Overall, we demonstrate that colloidal nanomaterials can exhibit a high level of self-organization behaviour at macroscopic-length scales.


Asunto(s)
Nanoestructuras , Nanoestructuras/química
10.
Analyst ; 148(17): 4099-4108, 2023 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-37486734

RESUMEN

Bladder cancer is a common cancer that is relatively hard to detect at an early stage because of its non-obvious symptoms. It is known that bladder cells can be found in urine samples which potentially could be used for early detection of bladder cancer. Raman spectroscopy is a powerful non-invasive tool for accessing biochemical information of cells. Combined with laser tweezers, to allow isolation of single cells, Raman spectroscopy has been used to characterise a number of bladder cells that might be found in a urine sample. Using principal component-canonical variates analysis (PC-CVA) and k-fold validation, the results shows that the invasive bladder cancer cells can be identified with accuracy greater than 87%. This demonstrates the potential of developing an early detection method that identifies the invasive bladder cancer cells in urine samples.


Asunto(s)
Pinzas Ópticas , Neoplasias de la Vejiga Urinaria , Humanos , Espectrometría Raman/métodos , Neoplasias de la Vejiga Urinaria/diagnóstico , Células Epiteliales , Análisis de Componente Principal
11.
J Chem Phys ; 159(1)2023 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-37409702

RESUMEN

Cation exchange is a versatile post-synthetic method to explore a wide range of nanoparticle compositions, phases, and morphologies. Recently, several studies have expanded the scope of cation exchange to magic-size clusters (MSCs). Mechanistic studies indicated that MSC cation exchange undergoes a two-stage reaction pathway instead of the continuous diffusion-controlled mechanism found in nanoparticle cation exchange reactions. The cation exchange intermediate, however, has not been well-identified despite it being the key to understanding the reaction mechanism. Only indirect evidence, such as exciton peak shifts and powder x-ray diffraction, has been used to indicate the formation of the cation exchange intermediate. In this paper, we investigate the unusual nature of cation exchange in nanoclusters using our previously reported CdS MSC. High-resolution mass spectra reveal two cation exchanged reaction intermediates [Ag2Cd32S33(L) and AgCd33S33(L), L: oleic acid] as well as the fully exchanged Ag2S cluster. Crystal and electronic structure characterizations also confirm the two-stage reaction mechanism. Additionally, we investigate the Cu/CdS MSC cation exchange reaction and find a similar two-stage reaction mechanism. Our study shows that the formation of dilutely exchanged intermediate clusters can be generally found in the first stage of the MSC cation exchange reaction. By exchanging different cations, these intermediate clusters can access varying properties compared to their unexchanged counterparts.

12.
Chirality ; 35(11): 846-855, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37331723

RESUMEN

Chiral materials with strong linear anisotropies are difficult to accurately characterize with circular dichroism (CD) because of artifactual contributions to their spectra from linear dichroism (LD) and birefringence (LB). Historically, researchers have used a second-order Taylor series expansion on the Mueller matrix to model the LDLB interaction effects on the spectra in conventional materials, but this approach may no longer be sufficient to account for the artifactual CD signals in emergent materials. In this work, we present an expression to model the measured CD using a third-order expansion, which introduces "pairwise interference" terms that, unlike the LDLB terms, cannot be averaged out of the signal. We find that the third-order pairwise interference terms can make noticeable contributions to the simulated CD spectra. Using numerical simulations of the measured CD across a broad range of linear and chiral anisotropy parameters, the LDLB interactions are most prominent in samples that have strong linear anisotropies (LD, LB) but negligible chiral anisotropies, where the measured CD strays from the chirality-induced CD by factors greater than 103 . Additionally, the pairwise interactions are most significant in systems with moderate-to-strong chiral and linear anisotropies, where the measured CD is inflated twofold, a figure that grows as linear anisotropies approach their maximum. In summary, media with moderate-to-strong linear anisotropy are in great danger of having their CD altered by these effects in subtle manners. This work highlights the significance of considering distortions in CD measurements through higher-order pairwise interference effects in highly anisotropic nanomaterials.

13.
Nano Lett ; 22(23): 9773-9780, 2022 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-36321690

RESUMEN

Magnetic memory combining plasmonics and magnetism is poised to dramatically increase the bit density and energy efficiency of light-assisted ultrafast magnetic storage, thanks to nanoplasmon-driven enhancement and confinement of light. Here we devise a new path for that, simultaneously enabling light-driven bit downscaling, reduction of the required energy for magnetic memory writing, and a subtle control over the degree of demagnetization in a magnetophotonic surface crystal. It features a regular array of truncated-nanocone-shaped Au-TbCo antennas showing both localized plasmon and surface lattice resonance modes. The ultrafast magnetization dynamics of the nanoantennas show a 3-fold resonant enhancement of the demagnetization efficiency. The degree of demagnetization is further tuned by activating surface lattice modes. This reveals a platform where ultrafast demagnetization is localized at the nanoscale and its extent can be controlled at will, rendering it multistate and potentially opening up so-far-unforeseen nanomagnetic neuromorphic-like systems operating at femtosecond time scales controlled by light.

14.
Angew Chem Int Ed Engl ; 62(28): e202301664, 2023 07 10.
Artículo en Inglés | MEDLINE | ID: mdl-36940229

RESUMEN

Within the realm of drug discovery, high-throughput experimentation techniques enable the rapid optimization of reactions and expedited generation of drug compound libraries for biological and pharmacokinetic evaluation. Herein we report the development of a segmented flow mass spectrometry-based platform to enable the rapid exploration of photoredox reactions for early-stage drug discovery. Specifically, microwell plate-based photochemical reaction screens were reformatted to segmented flow format to enable delivery to nanoelectrospray ionization-mass spectrometry analysis. This approach was demonstrated for the late-stage modification of complex drug scaffolds, as well as the subsequent structure-activity relationship evaluation of synthesized analogs. This technology is anticipated to expand the robust capabilities of photoredox catalysis in drug discovery by enabling high-throughput library diversification.


Asunto(s)
Descubrimiento de Drogas , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas , Catálisis , Espectrometría de Masa por Ionización de Electrospray/métodos , Ensayos Analíticos de Alto Rendimiento
15.
Acc Chem Res ; 54(3): 509-519, 2021 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-33434011

RESUMEN

ConspectusChemically induced transformations are postsynthetic processing reactions applied to first generation (as-synthesized) nanomaterials to modify property-defining factors such as atomic structure, chemical composition, surface chemistry, and/or morphology. Compared with conditions for direct synthesis of colloidal nanocrystals, postsynthetic chemical transformations can be conducted in relatively mild conditions with a more controllable process, which makes them suitable for the precise manipulation of nanomaterials and for trapping metastable phases that are typically inaccessible from the conventional synthetic routes. Each of the chemically induced transformations methods can result in substantial restructuring of the atomic structure, but their transformation pathways can be very different. And the converse is also true: the atomic structure of the parent material plays a large role in the pathway toward and the resulting chemically transformed product. Additionally, the characteristic length of the parent material greatly affects the structure, which affects the outcome of the reaction.In this Account, we show how the atomic structure and nanoscale size directs the product formation into materials that are inaccessible from analogous chemically transformations in bulk materials. Through examples from the three chemical transformation processes (cation/anion exchange, redox reactions, and ligand exchange and ligand etching), the effect of the atomic structure on chemical transformations is made apparent, and vice versa. For cation exchange, an anisotropic atomic lattice results in a unidirectional exchange boundary. And because the interface can extend through the full crystal, a substantial strain field can form, influencing the phase of the material. In the redox reaction that leads to the nanoscale Kirkendall effect, the atomic structure is the key to inverting the diffusion rates in a diffusion couple to form the hollow cores. And for ligand etching, if one of the materials in a heterostructure has a defected and\or defect-tolerant atomic structure, it can be preferentially etched and its atomic structure can undergo phase transformations while the other composition remains intact. For length scales, we show how the chemically induced transformations greatly differ between bulk, nanocrystal, and nanocluster characteristic sizes. For instance, the structural transformation on relatively large nanocrystals (2-100 nm) can be a continuous process when the activation volume is smaller than the nanocrystal, while for smaller nanoclusters (<2 nm) the transformation kinetics could be swift resulting in only discrete thermodynamic states. Comparing the two nanosystems (nanocrystals to small nanoclusters), we address how their atomic structural differences can direct the divergent transformation phenomena and the corresponding mechanisms. Understanding the nanoscale mechanisms of chemically induced transformations and how they differ from bulk processes is key to unlocking new science and for implementing this processing for functional materials.

16.
Cytokine ; 158: 155993, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36007427

RESUMEN

Allele bias is an epigenetic mechanism wherein only the maternal- or paternal-derived allele of a gene is preferentially expressed. Allele bias is used by T cells to regulate expression of numerous genes, including those which govern their development and response to cytokines. Here we demonstrate that human TH cell expression of the cytokine receptor gene IL12RB1 is subject to allele bias, and the extent to which this bias occurs is influenced by cells' differentiation status and two polymorphic sites in the IL12RB1 3'UTR. The single nucleotide polymorphisms (SNPs) at these sites, rs3746190 and rs404733, function to increase expression of their encoding allele. Modeling suggests this is due to a stabilizing effect of these SNPs on the predicted mRNA secondary structure. The SNP rs3746190 is also proximal to the predicted binding site of microRNA miR-1277, raising the possibility that miR-1277 cannot exert suppression in the presence of rs3746190. Functional experiments demonstrate, however, that miR-1277 suppression of IL12RB1 3'UTR expression-which itself has not been previously reported-is nevertheless independent of rs3746190. Collectively, these data demonstrate that rs3746190 and rs404733 are functional SNPs which regulate IL12RB1 allele bias in human TH cells.


Asunto(s)
Regiones no Traducidas 3' , Polimorfismo de Nucleótido Simple , Receptores de Interleucina-12 , Linfocitos T Colaboradores-Inductores , Regiones no Traducidas 3'/genética , Alelos , Sitios de Unión , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Polimorfismo de Nucleótido Simple/genética , Receptores de Interleucina-12/genética
17.
Langmuir ; 38(18): 5633-5644, 2022 05 10.
Artículo en Inglés | MEDLINE | ID: mdl-35475615

RESUMEN

There is an increasing need to reduce the silver content in silver-based inks or pastes and achieve low-temperature sintering for scalable and low-cost production of printed wearable electronics. This need depends on the ability to control the metal composition and the surface properties of the nanoinks. Alloying silver with copper provides a pathway for meeting the need in terms of cost reduction, but little is known about the composition controllability and the low-temperature sintering capability. We report herein a scalable wet chemical synthesis of bimetallic silver-copper alloy nanoinks with room temperature sintering properties. The bimetallic alloy nanoparticles with a controllable composition can be formulated as stable nanoinks. The nanoinks printed on paper substrates are shown to sinter under room temperature. In addition to composition dependence, the results reveal an intriguing dependence of sintering on humidity above the printed nanoink films. These findings are assessed based on theoretical simulation of the sintering processes via surface-mediated sintering and interparticle necking mechanisms in terms of nanoscale adsorption, adhesion and diffusion, and surface free energies. Implications of the findings for room temperature fabrication of wearable sensors are also discussed.


Asunto(s)
Nanopartículas del Metal , Plata , Aleaciones , Cobre/química , Nanopartículas del Metal/química , Plata/química , Temperatura
18.
J Org Chem ; 86(23): 17428-17436, 2021 12 03.
Artículo en Inglés | MEDLINE | ID: mdl-34808052

RESUMEN

Facilitating photoredox coupling reactions in process-friendly green solvents was achieved by the successful application of a dual Ir/Ni catalyst system with enhanced solubility properties. These photochemical reactions (specifically Br-Br sp2-sp3 cross electrophile coupling) are reported in a head to head comparison to the standard di-t-Bu bipyridine ligand Ir/Ni catalyst system. This presentation highlights the benefits of altering the solubility properties of the ligands used in the Ir/Ni dual catalyst.


Asunto(s)
Níquel , Catálisis , Ligandos , Oxidación-Reducción , Solventes
19.
J Chem Phys ; 155(14): 144702, 2021 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-34654287

RESUMEN

Efforts to improve energy storage depend greatly on the development of efficient electrode materials. Recently, strain has been employed as an alternate approach to improve ion mobility. While lattice strain has been well-researched in catalytic applications, its effects on electrochemical energy storage are largely limited to computational studies due to complexities associated with strain control in nanomaterials as well as loss of strain due to the phase change of the active material during charging-discharging. In this work, we overcome these challenges and investigate the effects of strain on supercapacitor performance in Li-ion-based energy devices. We synthesize epitaxial Fe3O4@MnFe2O4 (core@shell) nanoparticles with varying shell thickness to control the lattice strain. A narrow voltage window for electrochemical testing is used to limit the storage mechanism to lithiation-delithiation, preventing a phase change and maintaining structural strain. Cyclic voltammetry reveals a pseudocapacitive behavior and similar levels of surface charge storage in both strained- and unstrained-MnFe2O4 samples; however, diffusive charge storage in the strained sample is twice as high as the unstrained sample. The strained-MnFe2O4 electrode exceeds the performance of the unstrained-MnFe2O4 electrode in energy density by ∼33%, power density by ∼28%, and specific capacitance by ∼48%. Density functional theory shows lower formation energies for Li-intercalation and lower activation barrier for Li-diffusion in strained-MnFe2O4, corresponding to a threefold increase in the diffusion coefficient. The enhanced Li-ion diffusion rate in the strained-electrodes is further confirmed using the galvanostatic intermittent titration technique. This work provides a starting point to using strain engineering as a novel approach for designing high performance energy storage devices.

20.
Lung ; 199(1): 21-27, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33423072

RESUMEN

INTRODUCTION: E-cigarette or vaping product use associated lung injury (EVALI) has been an important health risk in both children and adults. The pathophysiology of EVALI is not well understood. However, it is speculated that certain substances such as Vitamin E Acetate (VEA), particularly in marijuana containing vape cartridges may result in lung injury and lead to respiratory dysfunction. EVALI is often seen in the absence of infections, but it has been found to be associated with both fungal and bacterial infections. Like EVALI, nontuberculous mycobacteria (NTM) pulmonary disease is also on the rise, but is primarily reported in immunocompromised individuals. Here, we present three immunocompetent individuals wherein pulmonary NTM infection co-occurred with vaping. METHODS: Medical information including patient history, laboratory, and radiograph reports were abstracted from electronic medical records from participating institutions located in the Bronx, NY, Philadelphia, PA, and Lexington, KY. RESULTS: All three cases were otherwise immunocompetent individuals with a significant history of vaping either nicotine and/or marijuana containing products. The pathogens isolated include Mycobacterium avium complex, M. xenopi, and M. gordonae. All three patients were treated for NTM. CONCLUSION: There is little reported on the association between vaping and NTM. It is possible that vaping may have rendered these individuals to be more susceptible to NTM colonization and infection. The possible mechanisms of vaping lung injury and pulmonary NTM are discussed.


Asunto(s)
Sistemas Electrónicos de Liberación de Nicotina , Enfermedades Pulmonares/microbiología , Infecciones por Mycobacterium no Tuberculosas/inducido químicamente , Vapeo/efectos adversos , Adolescente , Adulto , Antituberculosos/uso terapéutico , Asma/complicaciones , Femenino , Humanos , Inmunocompetencia , Pulmón/diagnóstico por imagen , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/tratamiento farmacológico , Masculino , Infecciones por Mycobacterium no Tuberculosas/diagnóstico , Infecciones por Mycobacterium no Tuberculosas/tratamiento farmacológico , Micobacterias no Tuberculosas , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Adulto Joven
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