RESUMEN
Orthorhombic perovskite GdFeO3 nanostructures are promising materials with multiferroic properties. In this study, a new low-temperature plasma-assisted approach is developed via dual anodic dissolution of solid metallic precursors for the preparation of perovskite GdFeO3 nanoparticles (NPs) that can be collected both as colloids as well as deposited as a thin film on a substrate. Two solid metallic foils of Gd and Fe are used as precursors, adding to the simplicity and sustainability of the method. The formation of the orthorhombic perovskite GdFeO3 phase is supported by high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman measurements, while a uniform elemental distribution of Gd, Fe, and O is confirmed by energy dispersive X-ray spectroscopy, proving the successful preparation of ternary compound NPs. The magnetic properties of the NPs show zero remnant magnetization typical of antiferromagnetic materials, and saturation at high fields that can be caused by spin interaction between Gd and Fe magnetic sublattices. The formation mechanism of ternary compound NPs in this novel plasma-assisted method is also discussed. This method is also modified to demonstrate the direct one-step deposition of thin films, opening up opportunities for their future applications in the fabrication of magnetic memory devices and gas sensors.
RESUMEN
We present the formation of a composite film made out of formamidinium lead iodide (FAPI) and molybdenum disulphide quantum dots (MoS2 QDs) and propose a corresponding photovoltaic device architecture based on a 'type-I' alignment of the two materials' electronic energy levels. The introduction of the MoS2 QDs has not compromised the overall crystallinity of the FAPI film and the composite absorber has shown improved stability. We report on the benefits of this composite film and energy band arrangement as the photogenerated carriers in MoS2 QDs, both positive and negative, are injected into the FAPI host matrix, resulting in an increased current density of 24.19 mA cm-2 compared to a current density of 19.83 mA cm-2 for the control device with FAPI only. The corresponding photoconversion efficiency increases from 12.6 to 15.0%. We also show that inclusion of MoS2 QDs in FAPI films resulted in a notable improvement in the fill factor and open-circuit voltage of the solar cells. Most importantly, MoS2 QDs enhanced the film stability by reducing defect formation and acting as passivating agents that minimize recombination losses and improve charge carrier transport. Our results suggest that a composite film in a type-I device architecture can introduce benefits for both future developments in perovskite solar cells and effectively tackling the longstanding challenges of carrier transport in QDs solar cells.
RESUMEN
Creating tin-alloyed silicon nanocrystals with tailored bandgap values is a significant challenge, primarily because a substantial concentration of tin is essential to observe useful changes in the electronic structure. However, high concentration of Sn leads to instability of the silicon-tin nanocrystals. This work introduces a completely new approach to doping and the modification of the electronic structure of nanoparticles by incorporating few-atom clusters in nanocrystals, deviating from isolated atom doping or attempting alloying. This approach is exemplified via a combined theoretical and experimental study on tin (Sn) 'cluster-doping' of silicon (Si) nanocrystals, motivated by the opportunities offered by the Si-Sn system with tailored band energy. First-principles modelling predicts two noteworthy outcomes: a considerably smaller bandgap of these nanocrystals even with a modest concentration of tin compared to an equivalent-sized pure silicon nanocrystal and an unexpected decrease in the bandgap of nanocrystals as the diameter of nanocrystals increases, contrary to the typical quantum confined behaviour. Experimental verification using atmospheric pressure microplasma synthesis confirms the stability of these nanocrystals under ambient conditions. The plasma-synthesised nanocrystals exhibited the predicted atypical size-dependent behaviour of the bandgap, which ranged from 1.6 eV for 1.4 nm mean diameter particles to 2.4 eV for 2.2 nm mean diameter particles.
RESUMEN
Exsolution of metal nanoparticles (NPs) on perovskite oxides has been demonstrated as a reliable strategy for producing catalyst-support systems. Conventional exsolution requires high temperatures for long periods of time, limiting the selection of support materials. Plasma direct exsolution is reported at room temperature and atmospheric pressure of Ni NPs from a model A-site deficient perovskite oxide (La0.43Ca0.37Ni0.06Ti0.94O2.955). Plasma exsolution is carried out within minutes (up to 15 min) using a dielectric barrier discharge configuration both with He-only gas as well as with He/H2 gas mixtures, yielding small NPs (<30 nm diameter). To prove the practical utility of exsolved NPs, various experiments aimed at assessing their catalytic performance for methanation from synthesis gas, CO, and CH4 oxidation are carried out. Low-temperature and atmospheric pressure plasma exsolution are successfully demonstrated and suggest that this approach could contribute to the practical deployment of exsolution-based stable catalyst systems.
RESUMEN
Objective. We aimed to report the real-world use and outcomes over time in immunocompromised individuals receiving tixagevimab/cilgavimab (T/C) pre-exposure prophylaxis (PrEP). Methods. This observational study included participants who received T/C PrEP, categorized into three groups: (i) No COVID-19 (NoC), i.e., participants who never had COVID-19; (ii) Hybrids (H), i.e., participants who had COVID-19 before PrEP; and (iii) Break-through Infections (BTIs), i.e., participants who had COVID-19 after PrEP. The study measured several immune markers at the administration of T/C (T0) at 3 (T1), 6 (T2), and 9 (T3) months afterward. These markers included: anti-receptor-binding domain (RBD) IgG antibodies; BA.5-neutralizing antibodies (nAbs); mucosal IgG; and T cell immunity. The incidence rate ratios for BTIs were analyzed using a Poisson regression model. Results. A total of 231 participants with a median age of 63 years (IQR 54.0-73.0). were included. Among these, 84% had hematological diseases and received a median of three vaccine doses. N = 72 participants belonged to the NoC group, N = 103 to the H group, and n = 56 to the BTI group (24%), with most BTIs being mild/moderate. The incidence rate (IR) of BTIs was 4.2 per 100 patient-months (95% CI 3.2-5.4), with no associated risk factors identified. There was a significant increase in anti-RBD IgG levels 3 months after the T/C administration in all groups, followed by a decline at 6 months, whereas at the same time points, geometric mean titers (GMTs) of anti-BA.5 nAbs were low for all groups and were around or below the detection threshold. No significant changes were observed in IFN-γ levels. The mucosal immune response was observed only 3 months after the PrEP administration. Conclusion. We provided a real-world experience model on the clinical efficacy of T/C PrEP in preventing severe COVID-19 during the Omicron wave through a comprehensive virological and immunological study. While waiting for the arrival of new monoclonal antibodies that can effectively neutralize the most recent variants, T/C PrEP remains the only viable strategy in the available armamentarium today to prevent COVID-19 complications in an extremely fragile population with suboptimal immune responses to COVID-19 vaccines.
RESUMEN
This study examines the effect of quantum confinement and surface orientations on the electronic properties of NiO quantum dots. It compares NiO nanocrystals produced via atmospheric-pressure microplasma and femtosecond laser (fs-laser) ablation in water, finding that both methods yield quantum-confined nanocrystals with a defined face-centered cubic lattice. Notably, fs-laser synthesis generates crystalline nanocrystals from both crystalline and amorphous targets. While the electronic properties, i.e., energy of the highest occupied molecular orbital and lowest unoccupied molecular orbital (LUMO), of microplasma-synthesized NiO nanocrystals are consistent with the literature, the electronic characteristics of NiO nanocrystals produced by a fs-laser, particularly the high-lying LUMO level, are unusual for NiO quantum dots. Supported by density functional theory calculations, we show that the observed level positions are related to the different polar and nonpolar faces of the nanocrystal surface.
RESUMEN
We estimated the dynamics of the neutralizing response against XBB sublineages and T cell response in persons with HIV (PWH) with previous AIDS and/or CD4 < 200/mm3 receiving the bivalent original strain/BA.4-5 booster dose in fall 2022. Samples were collected before the shot (Day 0), 15 days, 3, and 6 months after. PWH were stratified by immunization status: hybrid immunity (HI; vaccination plus COVID-19) versus nonhybrid immunity (nHI; vaccination only). Fifteen days after the booster, 16% and 30% of PWH were nonresponders in terms of anti-XBB.1.16 or anti-EG.5.1 nAbs, respectively. Three months after, a significant waning of anti-XBB.1.16, EG.5.1 and -XBB.1 nAbs was observed both in HI and nHI but nAbs in HI were higher than in nHI. Six months after both HI and nHI individuals displayed low mean levels of anti-XBB.1.16 and EG.5.1 nAbs. Regarding T cell response, IFN-γ values were stable over time and similar in HI and nHI. Our data showed that in PWH, during the prevalent circulation of the XBB.1.16, EG.5.1, and other XBB sublineages, a mRNA bivalent vaccine might not confer broad protection against them. With a view to the 2023/2024 vaccination campaign, the use of the monovalent XBB.1.5 mRNA vaccine should be urgently warranted in PWH to provide adequate protection.
Asunto(s)
COVID-19 , Infecciones por VIH , Humanos , COVID-19/prevención & control , Programas de Inmunización , ARN Mensajero , Estaciones del Año , Vacunas de ARNm , Anticuerpos Neutralizantes , Anticuerpos AntiviralesRESUMEN
Progress in electrochemical water-splitting devices as future renewable and clean energy systems requires the development of electrodes composed of efficient and earth-abundant bifunctional electrocatalysts. This study reveals a novel flexible and bifunctional electrode (NiO@CNTR) by hybridizing macroscopically assembled carbon nanotube ribbons (CNTRs) and atmospheric plasma-synthesized NiO quantum dots (QDs) with varied loadings to demonstrate bifunctional electrocatalytic activity for stable and efficient overall water-splitting (OWS) applications. Comparative studies on the effect of different electrolytes, e.g., acid and alkaline, reveal a strong preference for alkaline electrolytes for the developed NiO@CNTR electrode, suggesting its bifunctionality for both HER and OER activities. Our proposed NiO@CNTR electrode demonstrates significantly enhanced overall catalytic performance in a two-electrode alkaline electrolyzer cell configuration by assembling the same electrode materials as both the anode and the cathode, with a remarkable long-standing stability retaining â¼100% of the initial current after a 100 h long OWS run, which is attributed to the "synergistic coupling" between NiO QD catalysts and the CNTR matrix. Interestingly, the developed electrode exhibits a cell potential (E10) of only 1.81 V with significantly low NiO QD loading (83 µg/cm2) compared to other catalyst loading values reported in the literature. This study demonstrates a potential class of carbon-based electrodes with single-metal-based bifunctional catalysts that opens up a cost-effective and large-scale pathway for further development of catalysts and their loading engineering suitable for alkaline-based OWS applications and green hydrogen generation.
RESUMEN
The 2022 global spread of Monkeypox Virus (MPXV) underlined the need to investigate safe-handling procedures of clinical and research samples. Here we evaluated the efficiency in reducing MPXV infectious titer of Triton X-100 (0.1 and 0.2%), UV-C irradiation (15 or 30 min), and heat (56 °C 30 min or 70 °C 5 min). The treatment of MPXV at 70 °C resulted in the strongest decrease of MPXV infectious titer (5.4 Log TCID50/mL), 56 °C and UV-C had a lighter impact (3.9 and 4.3Log), Triton X-100 was less efficient (1.8-2.5Log). Notably, SARS-CoV-2 was much more susceptible to Triton X-100 (4.0 Log decrease). UV-C had the highest impact on MPXV DNA detection by PCR (2.2-4.3 Ct value increase); protein detection by ELISA was dramatically impaired by heating. Overall, UV-C and heating were more effective in lowering MPXV infectious titer but their impact on nucleic acids or protein detection assays must be considered.
Asunto(s)
Monkeypox virus , Mpox , Humanos , Monkeypox virus/genética , Octoxinol , SARS-CoV-2RESUMEN
An atmospheric-pressure plasma system is developed and is used to treat carbon nanotube assemblies, producing a hybrid carbon-zinc structure. This system is integrated into a floating-catalyst chemical vapor deposition furnace used for the synthesis of macroscopic assemblies of carbon nanotubes to allow for the in-line, continuous, and single-step production of nano-composite materials. Material is deposited from a sacrificial zinc wire in the form of nanoparticles and can coat the surface of the individual carbon nanotubes as they form. Additionally, it is found that the deposited materials penetrate further into the carbon nanotube matrix than a comparable post-synthesis deposition, improving the uniformity of the material through the thickness. Thus, a single-step metal-based coating and carbon nanotube synthesis process which can form the basis of production scale manufacturing of metal-carbon nanotube composite materials with an atmospheric-pressure plasma system are demonstrated.
RESUMEN
(1) Background: Waning of neutralizing and cell-mediated immune response after the primary vaccine cycle (PVC) and the first booster dose (BD) is of concern, especially for PLWH with a CD4 count ≤200 cells/mm3. (2) Methods: Neutralizing antibodies (nAbs) titers by microneutralization assay against WD614G/Omicron BA.1 and IFNγ production by ELISA assay were measured in samples of PLWH at four time points [2 and 4 months post-PVC (T1 and T2), 2 weeks and 5 months after the BD (T3 and T4)]. Participants were stratified by CD4 count after PVC (LCD4, ≤200/mm3; ICD4, 201-500/mm3, and HCD4, >500/mm3). Mixed models were used to compare mean responses over T1-T4 across CD4 groups. (3) Results: 314 PLWH on ART (LCD4 = 56; ICD4 = 120; HCD4 = 138) were enrolled. At T2, levels of nAbs were significantly lower in LCD4 vs. ICD4/HCD4 (p = 0.04). The BD was crucial for increasing nAbs titers above 1:40 at T3 and up to T4 for WD614G. A positive T cell response after PVC was observed in all groups, regardless of CD4 (p = 0.31). (4) Conclusions: Waning of nAbs after PVC was more important in LCD4 group. The BD managed to re-establish higher levels of nAbs against WD614G, which were retained for 5 months, but for shorter time for Omicron BA.1. The T cellular response in the LCD4 group was lower than that seen in participants with higher CD4 count, but, importantly, it remained above detectable levels over the entire study period.
RESUMEN
The design and fabrication of eco-friendly and cost-effective (photo)electrocatalysts for the oxygen evolution reaction (OER) is a key research goal for a proper management of water splitting to address the global energy crisis. In this work, we focus on the preparation of supported MnO2/graphitic carbon nitride (g-CN) OER (photo)electrocatalysts by means of a novel preparation strategy. The proposed route consists of the plasma enhanced-chemical vapor deposition (PE-CVD) of MnO2 nanoarchitectures on porous Ni scaffolds, the anchoring of controllable g-CN amounts by an amenable electrophoretic deposition (EPD) process, and the ultimate thermal treatment in air. The inherent method versatility and flexibility afforded defective MnO2/g-CN nanoarchitectures, featuring a g-CN content and nano-organization tunable as a function of EPD duration and the used carbon nitride precursor. Such a modulation had a direct influence on OER functional performances, which, for the best composite system, corresponded to an overpotential of 430 mV at 10 mA/cm2, a Tafel slope of ≈70 mV/dec, and a turnover frequency of 6.52 × 10-3 s-1, accompanied by a very good time stability. The present outcomes, comparing favorably with previous results on analogous systems, were rationalized on the basis of the formation of type-II MnO2/g-CN heterojunctions, and yield valuable insights into this class of green (photo)electrocatalysts for end uses in solar-to-fuel conversion and water treatment.
RESUMEN
Highly stable and environmentally friendly nitrogen-doped graphite quantum dots consisting of â¼12 layers of graphene, average diameter of â¼7.3 nm, prepared by atmospheric pressure microplasma are reported to have blue emission due to surface states created by nitrogen doping (9 atomic%) and reaction with oxygen. The low-temperature synthesis method requires simple precursors in water, with no annealing or filtration, producing crystalline disc-shaped quantum dots with â¼68% photoluminescence emission quantum yield at 420 nm excitation and that have shown stability for more than one month after the synthesis. The nitrogen doping in the quantum dots mainly occurs in graphitic core as substituted type of doping (63-67 atomic%) and the amount of doping is sufficient to create emissive states without impacting the core structure. The optical and chemical properties do not undergo serious retardation even with re-dispersion suggesting easy applicability for cellular imaging or optoelectronics.
RESUMEN
OBJECTIVES: To investigate immunogenicity of SARS-CoV-2 vaccine third booster dose (3BD; fifth dose) with bivalent vaccine original/BA4/5 vaccine in people living with HIV (PLWH). METHODS: This is an observational cohort study to evaluate the outcomes of SARS-CoV-2 vaccination (HIV-VAC study). We analyzed microneutralization assay and interferon-γ production in 48 PLWH on antiretroviral therapy with clusters of differentiation (CD4) count <200 cell/mm3 and/or previous AIDS according to immunization status: vaccinated PLWH who had a previous SARS-CoV-2 infection (hybrid immunization, HI) vs those only vaccinated (non-hybrid immunization, nHI) and current CD4 count. RESULTS: After 15 days from its administration (T1), the 3BD bivalent messenger RNA vaccine elicited a statistically significant increase of neutralizing antibodies (nAbs) geometric mean titers from T0 to T1 against W-D614G (fold increase 4.8; P <0.0001), BA.5 (8.6 P <0.0001), BQ.1.1 (6.4, P <0.0001) and XBB.1 (6.5, P <0.0001). When compared to BA.5, nAbs geometric mean titers against BQ.1.1 and XBB.1 decreased by 3.5 and 4.1-fold, respectively. After controlling for age, years from AIDS diagnosis, CD4 count at administration and CD4 count nadir, the fold change reduction in nAbs response to other variants of concerns as compared to BA.1, was larger in participants with HI vs those nHI: 0.59 lower (95% confidence interval 0.36-0.97, P = 0.04) for BQ.1.1 and 0.67 lower (95% confidence interval: 0.47-0.96, P = 0.03) for XBB.1. In contrast, the analysis carried little evidence for an association between current CD4 count and response to the fifth dose of bivalent vaccine. Furthermore, cell-mediated immunity remained stable. CONCLUSION: Our data support the current recommendation of offering bivalent mRNA vaccine booster doses to PLWH with low CD4 count or previous AIDS at first vaccination, especially in those who never previously acquired SARS-CoV-2 and regardless of current CD4 count.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida , COVID-19 , Humanos , Vacunas contra la COVID-19 , Linfocitos T , COVID-19/prevención & control , SARS-CoV-2 , Vacunas Sintéticas , Vacunas Combinadas , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Vacunas de ARNmRESUMEN
Nanocrystals have a great potential for future materials with tunable bandgap, due to their optical properties that are related with the material used, their sizes and their surface termination. Here, we concentrate on the silicon-tin alloy for photovoltaic applications due to their bandgap, lower than bulk Si, and also the possibility to activate direct band to band transition for high tin concentration. We synthesized silicon-tin alloy nanocrystals (SiSn-NCs) with diameter of about 2-3 nm by confined plasma technique employing a femtosecond laser irradiation on amorphous silicon-tin substrate submerged in liquid media. The tin concentration is estimated to be [Formula: see text], being the highest Sn concentration for SiSn-NCs reported so far. Our SiSn-NCs have a well-defined zinc-blend structure and, contrary to pure tin NCs, also an excellent thermal stability comparable to highly stable silicon NCs. We demonstrate by means of high resolution synchrotron XRD analysis (SPring 8) that the SiSn-NCs remain stable from room temperature up to [Formula: see text] with a relatively small expansion of the crystal lattice. The high thermal stability observed experimentally is rationalized by means of first-principle calculations.
RESUMEN
Owing to their superior optical and thermal properties over conventional fluids, nanofluids represent an innovative approach for use as working fluids in direct-absorption solar collectors for efficient solar-to-thermal energy conversion. The application of nanofluids in direct-absorption solar collectors demands high-performance solar thermal nanofluids that exhibit exceptional physical and chemical stability over long periods and under a variety of operating, fluid dynamics, and temperature conditions. In this review, we discuss recent developments in the field of nanofluids utilized in direct-absorption solar collectors in terms of their preparation techniques, optical behaviours, solar thermal energy conversion performance, as well as their physical and thermal stability, along with the experimental setups and calculation approaches used. We also highlight the challenges associated with the practical implementation of nanofluid-based direct-absorption solar collectors and offer suggestions and an outlook for the future.
RESUMEN
We discuss the electronic properties of quantum-confined nanocrystals. In particular, we show how, starting from the discrete molecular states of small nanocrystals, an approximate band structure (quasi-band structure) emerges with increasing particle size. Finite temperature is found to broaden the discrete states in energy space forming even for nanocrystals in the quantum-confinement regime quasi-continuous bands in k-space. This bands can be, to a certain extend, interpreted along the lines of standard band structure theory, while taking also finite size and surface effects into account. We discuss this on various prototypical nanocrystal systems.
RESUMEN
BACKGROUND: Lymphopenia, particularly when restricted to the T-cell compartment, has been described as one of the major clinical hallmarks in patients with coronavirus disease 2019 (COVID-19) and proposed as an indicator of disease severity. Although several mechanisms fostering COVID-19-related lymphopenia have been described, including cell apoptosis and tissue homing, the underlying causes of the decline in T-cell count and function are still not completely understood. OBJECTIVE: Given that viral infections can directly target thymic microenvironment and impair the process of T-cell generation, we sought to investigate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on thymic function. METHODS: We performed molecular quantification of T-cell receptor excision circles and κ-deleting recombination excision circles to assess, respectively, T- and B-cell neogenesis in SARS-CoV-2-infected patients. We developed a system for in vitro culture of primary human thymic epithelial cells (TECs) to mechanistically investigate the impact of SARS-CoV-2 on TEC function. RESULTS: We showed that patients with COVID-19 had reduced thymic function that was inversely associated with the severity of the disease. We found that angiotensin-converting enzyme 2, through which SARS-CoV-2 enters the host cells, was expressed by thymic epithelium, and in particular by medullary TECs. We also demonstrated that SARS-CoV-2 can target TECs and downregulate critical genes and pathways associated with epithelial cell adhesion and survival. CONCLUSIONS: Our data demonstrate that the human thymus is a target of SARS-CoV-2 and thymic function is altered following infection. These findings expand our current knowledge of the effects of SARS-CoV-2 infection on T-cell homeostasis and suggest that monitoring thymic activity may be a useful marker to predict disease severity and progression.
Asunto(s)
COVID-19 , Linfopenia , Humanos , COVID-19/metabolismo , SARS-CoV-2 , Timo , Linfopenia/genética , Gravedad del PacienteRESUMEN
Histone acetylation/deacetylation play an essential role in modifying chromatin structure and in regulating cell plasticity in eukaryotic cells. Therefore, histone deacetylase (HDAC) pharmacological inhibitors are promising tools in the therapy of fibrotic diseases and in cancer. Peritoneal fibrosis is a pathological process characterized by many cellular and molecular alterations, including the acquisition of invasive/pro-fibrotic abilities by mesothelial cells (MCs) through induction of mesothelial to mesenchymal transition (MMT). The aim of this study was to characterize the molecular mechanism of the antifibrotic role of HDAC1 inhibition. Specifically, treatment with MS-275, an HDAC1-3 inhibitor previously known to promote MMT reversal, induced the expression of several TGFBRI mRNA-targeting miRNAs. Among them, miR-769-5p ectopic expression was sufficient to promote MMT reversal and to limit MC migration and invasion, whereas miR-769-5p silencing further enhanced mesenchymal gene expression. These results were confirmed by HDAC1 genetic silencing. Interestingly, miR-769-5p silencing maintained mesenchymal features despite HDAC1 inhibition, thus indicating that it is necessary to drive MMT reversal induced by HDAC1 inhibition. Besides TGFBRI, miR-769-5p was demonstrated to target SMAD2/3 and PAI-1 expression directly. When analyzing molecular mechanisms underlying miR-769-5p expression, we found that the transcription factor Wilms' tumor 1 (WT1), a master gene controlling MC development, binds to the miR-769-5p promoter favoring its expression. Interestingly, both WT1 expression and binding to miR-769-5p promoter were increased by HDAC1 inhibition and attenuated by TGFß1 treatment. Finally, we explored the significance of these observations in the cell-to-cell communication: we evaluated the ability of miR-769-5p to be loaded into extracellular vesicles (EVs) and to promote MMT reversal in recipient mesenchymal-like MCs. Treatment of fibrotic MCs with EVs isolated from miR-769-5p over-expressing MCs promoted the down-regulation of specific mesenchymal targets and the reacquisition of an epithelial-like morphology. In conclusion, we highlighted an HDAC1-WT1-miR-769-5p axis potentially relevant for therapies aimed at counteracting organ fibrosis.