Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 112
Filtrar
1.
ACS Nano ; 18(8): 6638-6649, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38350032

RESUMO

Strong metal-support interactions (SMSIs) are well-known in the field of heterogeneous catalysis to induce the encapsulation of platinum (Pt) group metals by oxide supports through high temperature H2 reduction. However, demonstrations of SMSI overlayers have largely been limited to reducible oxides, such as TiO2 and Nb2O5. Here, we show that the amorphous native surface oxide of plasmonic aluminum nanocrystals (AlNCs) exhibits SMSI-induced encapsulation of Pt following reduction in H2 in a Pt structure dependent manner. Reductive treatment in H2 at 300 °C induces the formation of an AlOx SMSI overlayer on Pt clusters, leaving Pt single-atom sites (Ptiso) exposed available for catalysis. The remaining exposed Ptiso species possess a more uniform local coordination environment than has been observed on other forms of Al2O3, suggesting that the AlOx native oxide of AlNCs presents well-defined anchoring sites for individual Pt atoms. This observation extends our understanding of SMSIs by providing evidence that H2-induced encapsulation can occur for a wider variety of materials and should stimulate expanded studies of this effect to include nonreducible oxides with oxygen defects and the presence of disorder. It also suggests that the single-atom sites created in this manner, when combined with the plasmonic properties of the Al nanocrystal core, may allow for site-specific single-atom plasmonic photocatalysis, providing dynamic control over the light-driven reactivity in these systems.

2.
ACS Nano ; 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38324804

RESUMO

Copper phosphide (Cu3-xP) nanocrystals are promising materials for nanoplasmonics due to their substoichiometric composition, enabling the generation and stabilization of excess delocalized holes and leading to localized surface plasmon resonance (LSPR) absorption in the near-IR. We present three Cu-coupled redox chemistries that allow postsynthetic modulation of the delocalized hole concentrations and corresponding LSPR absorption in colloidal Cu3-xP nanocrystals. Changes in the structural, optical, and compositional properties are evaluated by powder X-ray diffraction, electronic absorption spectroscopy, 31P magic-angle spinning solid-state nuclear magnetic resonance spectroscopy, and elemental analysis. The redox chemistries presented herein can be used to access nanocrystals with LSPR energies of 660-890 meV, a larger range than has been possible through synthetic tuning alone. In addition to utilizing previously reported redox chemistries used for copper chalcogenide nanocrystals, we show that the largest structural and LSPR modulation is achieved using a divalent metal halide and trioctylphosphine. Specifically, nanocrystals treated with zinc iodide and trioctylphosphine have the smallest unit-cell volume (295.2 Å3) reported for P63cm Cu3-xP, indicating more Cu vacancies than have been previously observed. Overall, these redox chemistries present valuable insight into controlling the optical and structural properties of Cu3-xP.

3.
Nanomicro Lett ; 16(1): 82, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38214786

RESUMO

Aqueous zinc-ion batteries are promising due to inherent safety, low cost, low toxicity, and high volumetric capacity. However, issues of dendrites and side reactions between zinc metal anode and the electrolyte need to be solved for extended storage and cycle life. Here, we proposed that an electrolyte additive with an intermediate chelation strength of zinc ion-strong enough to exclude water molecules from the zinc metal-electrolyte interface and not too strong to cause a significant energy barrier for zinc ion dissociation-can benefit the electrochemical stability by suppressing hydrogen evolution reaction, overpotential growth, and dendrite formation. Penta-sodium diethylene-triaminepentaacetic acid salt was selected for such a purpose. It has a suitable chelating ability in aqueous solutions to adjust solvation sheath and can be readily polarized under electrical loading conditions to further improve the passivation. Zn||Zn symmetric cells can be stably operated over 3500 h at 1 mA cm-2. Zn||NH4V4O10 full cells with the additive show great cycling stability with 84.6% capacity retention after 500 cycles at 1 A g-1. Since the additive not only reduces H2 evolution and corrosion but also modifies Zn2+ diffusion and deposition, highlyreversible Zn electrodes can be achieved as verified by the experimental results. Our work offers a practical approach to the logical design of reliable electrolytes for high-performance aqueous batteries.

4.
ChemSusChem ; 17(5): e202301819, 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38288777

RESUMO

Currently, the durability of electrode materials remains a big obstacle to the widespread adoption of proton exchange membrane fuel cells (PEMFCs). Herein thiourea and sodium dodecyl benzene sulfonate (SDS) were employed as sulfur source and carbon source to modify the pristine carbon black (Ketjen black EC300 J). A highly durable carbon supported Pt nanosized catalyst with higher platinum utilization for oxygen reduction reaction (ORR) in PEMFCs was produced by doping elemental sulfur into carbon supports and decreasing the carbon pore sizes and volume through a successive impregnation technique. The catalyst exhibits an initial activity of 0.167 A mgPt -1 at 0.90 V and demonstrates minimal activity loss after acceleration stress test (30,000 cycles of AST). The half-wave potential loss for representative sample (Pt/S-C-3) is only 14 mV with only 21.8 % ECSA decrease, 27.5 % MA loss and 5.9 % SA loss. A sintering test at various temperature shows a minor average size increase for sulfur-doped carbon (S-C) supported one (from 2.09 to 2.52 nm). In single-cell test, the MEA sample employing the platinum catalyst on modified carbon as cathode exhibited almost negligible performance loss after 30,000 cycles of AST.

5.
Small ; 20(6): e2304799, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37786289

RESUMO

Garnet-type Li7 La3 Zr2 O12 (LLZO) solid-state electrolytes hold great promise for the next-generation all-solid-state batteries. An in-depth understanding of the phase transformation during synthetic processes is required for better control of the crystallinity and improvement of the ionic conductivity of LLZO. Herein, the phase transformation pathways and the associated surface amorphization are comparatively investigated during the sol-gel and solid-state syntheses of LLZO using in situ heating transmission electron microscopy (TEM). The combined ex situ X-ray diffraction and in situ TEM techniques are used to reveal two distinct phase transformation pathways (precursors â†’ La2 Zr2 O7  â†’ LLZO and precursors â†’ LLZO) and the subsequent layer-by-layer crystal growth of LLZO on the atomic scale. It is also demonstrated that the surface amorphization surrounding the LLZO crystals is sensitive to the postsynthesis cooling rate and significantly affects the ionic conductivity of pelletized LLZO. This work brings up a critical but often overlooked issue that may greatly exacerbate the Li-ion conductivity by undesired synthetic conditions, which can be leveraged to ameliorate the overall crystallinity to improve the electrochemical performance of LLZO. These findings also shed light on the significance of optimizing surface structure to ensure superior performance of Li-ion conductors.

6.
Artigo em Inglês | MEDLINE | ID: mdl-37976965

RESUMO

Family selection is an important method in fish aquaculture because growth is the most important economic trait. Fast-and slow-growing families of tiger puffer fish (Takifugu rubripes) have been established through family selection. The development of teleost fish is primarily controlled by the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis that includes the hypothalamus-pituitary-liver. In this study, the molecular mechanisms underlying T. rubripes growth were analyzed by comparing transcriptomes from fast- and slow-growing families. The expressions of 214 lncRNAs were upregulated, and those of 226 were downregulated in the brain tissues of the fast-growing T. rubripes family compared to those of the slow-growing family. Differentially expressed lncRNAs centrally regulate mitogen-activated protein kinase (MAPK) and forkhead box O (FoxO) signaling pathways. Based on the results of lncRNA-gene network construction, we found that lncRNA3133.13, lncRNA23169.1, lncRNA23145.1, and lncRNA23141.3 regulated all four genes (igf1, mdm2, flt3, and cwf19l1). In addition, lncRNA7184.10 may be a negative regulator of rasgrp2 and a positive regulator of gadd45ga, foxo3b, and dusp5. These target genes are associated with the growth and development of organisms through the PI3K/AKT and MAPK/ERK pathways. Overall, transcriptomic analyses of fast- and slow-growing families of T. rubripes provided insights into the molecular mechanisms of teleost fish growth rates. Further, these analyses provide evidence for key genes related to growth regulation and the lncRNA expression regulatory network that will provide a framework for improving puffer fish germplasm resources.


Assuntos
RNA Longo não Codificante , Animais , RNA Longo não Codificante/genética , Takifugu/genética , Takifugu/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Perfilação da Expressão Gênica , Transcriptoma
7.
Nat Commun ; 14(1): 7885, 2023 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-38036495

RESUMO

Recent studies have reported worldwide vegetation suppression in response to increasing atmospheric vapor pressure deficit (VPD). Here, we integrate multisource datasets to show that increasing VPD caused by warming alone does not suppress vegetation growth in northern peatlands. A site-level manipulation experiment and a multiple-site synthesis find a neutral impact of rising VPD on vegetation growth; regional analysis manifests a strong declining gradient of VPD suppression impacts from sparsely distributed peatland to densely distributed peatland. The major mechanism adopted by plants in response to rising VPD is the "open" water-use strategy, where stomatal regulation is relaxed to maximize carbon uptake. These unique surface characteristics evolve in the wet soil‒air environment in the northern peatlands. The neutral VPD impacts observed in northern peatlands contrast with the vegetation suppression reported in global nonpeatland areas under rising VPD caused by concurrent warming and decreasing relative humidity, suggesting model improvement for representing VPD impacts in northern peatlands remains necessary.


Assuntos
Gases , Plantas , Pressão de Vapor , Pressão Atmosférica , Carbono
8.
Oncol Lett ; 26(6): 542, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38020304

RESUMO

Epigenetic modification is crucial for transmitting genetic information, while abnormalities in DNA methylation modification are primarily associated with cancer and neurological diseases. As a multifunctional epigenetic modifier, ubiquitin like with PHD and ring finger domains 1 (UHRF1) mainly affects cell energy metabolism and cell cycle control. It also inhibits the transcription of tumor suppressor genes through DNA and/or histone methylation modifications, promoting the occurrence and development of cancer. Therefore, comprehensively understanding the molecular mechanism of the epigenetic modification of UHRF1 in tumors will help identify targets for inhibiting the expression and function of UHRF1. Notably, each domain of UHRF1 functions as a whole and differently. Thus, the abnormality of any domain can lead to a change in phenotype or disease. However, the specific regulatory mechanism and proteins of each domain have not been fully elucidated. The present review aimed to contribute to the study of the regulatory mechanism of UHRF1 to a greater extent in different cancers and provide ideas for drug research by clarifying the function of UHRF1 domains.

9.
Clin. transl. oncol. (Print) ; 25(10): 2938-2949, oct. 2023. graf
Artigo em Inglês | IBECS | ID: ibc-225075

RESUMO

Renal cell carcinoma (RCC) with poor prognosis and high incidence rate is a common malignant disease. Current therapies could bring little benefit for the patients with advanced-stage RCC. PDIA2 is an isomerase responsible for protein folding and its role in cancer including RCC is under investigation. In this study, we found that PDIA2 was expressed much higher in RCC tissues than the control but the methylation level of PDIA2 promoter was lower based on the TCGA data. Patients with higher PDIA2 expression exerted worse survival. In clinical specimen, PDIA2 expression was correlated to patients’ clinical factors such as TNM stage (I/II vs III/IV, p = 0.025) and tumor size (≤ 7 cm vs > 7 cm, p = 0.004). Moreover, K-M analysis showed that PDIA2 was associated with patients’ survival in RCC. PDIA2 was expressed much higher in cancer cells A498 than 786-O than that in 293 T cells. After PDIA2 was knocked down, cell proliferation, migration and invasion was potently inhibited. But cell apoptotic rate increased reversely. Furthermore, the efficacy of Sunitinib on RCC cells was strengthened after PDIA2 knockdown. In addition, knockdown of PDIA2 gene leaded to downregulation of levels of JNK1/2, phosphorylated JNK1/2, c-JUN, and Stat3. But this inhibition was partially released when JNK1/2 was overexpressed. In consistent, cell proliferation was also partially recovered. In summary, PDIA2 plays important role in progression of RCC and JNK signaling pathway might be regulated by PDIA2. This study suggests PDIA2 as a candidate target for therapy of RCC (AU)


Assuntos
Humanos , Sistema de Sinalização das MAP Quinases/genética , Carcinoma de Células Renais/patologia , Carcinoma de Células Renais/genética , Neoplasias Renais/patologia , Neoplasias Renais/genética , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Prognóstico
15.
Front Immunol ; 14: 1152899, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37559719

RESUMO

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly pathogenic to humans and has caused the ongoing coronavirus disease 2019 (COVID-19) pandemic. Vaccines are one of the efficient ways to prevent the viral infection. After COVID-19 vaccination, the monitoring of the dynamic change in neutralizing antibodies is necessary to determine booster requirements. Methods: We estimated the effectiveness of the inactivated vaccines by monitoring dynamic SARS-CoV-2 neutralizing antibodies for over 2 years. Additionally, we also investigated the activation of T lymphocytes (CD3+ T cells) after three doses of the inactivated vaccine. Result: The results showed that the rate of reduction of SARS-CoV-2 neutralizing antibody levels gradually showed after each booster dose. The IgG/IgM level at 9 months after the third vaccination were significantly higher than those at 6 months after the second dose (p<0.0001). The expression of CD25+T cell in 18-35 age group was significantly higher than that in the other groups. Nine months after the third dose (the time of last blood sample collection), the expression of CD25+T cell in the 18-35 age group was significantly higher than that at 6 months after the second dose. CD25+T cell in the 18-35 years old group was significantly higher than 6 months after the second vaccination. Conclusion: CD25, a late activation marker of lymphocytes and high-activity memory T cell subgroup, exhibited higher levels at the later stages after vaccination. COVID-19 booster vaccination in older adults and regular testing of SARS-CoV-2 neutralizing antibodies are recommended. Booster doses should be administered if the antibody level falls below the 30% inhibition rate.


Assuntos
Vacinas contra COVID-19 , COVID-19 , Humanos , Idoso , Lactente , Adolescente , Adulto Jovem , Adulto , Vacinas contra COVID-19/efeitos adversos , COVID-19/prevenção & controle , SARS-CoV-2 , Anticorpos Neutralizantes , Anticorpos Antivirais , Vacinas de Produtos Inativados/efeitos adversos
16.
J Arthroplasty ; 38(12): 2638-2643, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37286058

RESUMO

BACKGROUND: The aim of this study was to compare outcomes after total hip arthroplasty (THA) in patients who have preoperative asymptomatic gluteal tendinosis (aGT) to a control group with no gluteal tendinosis (GT). METHODS: A retrospective analysis was performed using data from patients who underwent THA between March 2016 and October 2020. An aGT was diagnosed using hip magnetic resonance imaging (MRI) without clinical symptoms. Patients who had aGT were matched (1:1) to patients without GT on MRI. A total of 56 aGT hips and 56 hips without GT were found using propensity-score matching. Patient-reported outcomes, intraoperative macroscopic evaluation, outcome measurements, postoperative physical examinations, complications, and revisions were compared for both groups. RESULTS: When compared to preoperative outcomes, both groups demonstrated significant improvements in patients-reported outcomes at the final follow-up. There were no significant differences between both groups for preoperative scores, 2-year postoperative outcome scores, or the magnitude of improvement. Patients in the aGT group were significantly less likely to obtain the MCID for the SF-36 MCS score (50.2 versus 69.3%, P = .034). However, there were no other differences in the rates of meeting the MCID between both groups. The aGT group demonstrated significantly higher rates of partial tendon degeneration of the gluteus medius muscle. CONCLUSION: Asymptomatic gluteal tendinosis patients who have osteoarthritis and undergo THA may expect favorable patients-reported outcomes at minimum 2-year follow-up. These results were comparable with those of a control group of patients without gluteal tendinosis. LEVEL OF EVIDENCE: III.


Assuntos
Artroplastia de Quadril , Tendinopatia , Humanos , Artroplastia de Quadril/métodos , Estudos Retrospectivos , Músculo Esquelético/cirurgia , Tendões/cirurgia , Tendinopatia/cirurgia , Resultado do Tratamento , Articulação do Quadril/diagnóstico por imagem , Articulação do Quadril/cirurgia , Medidas de Resultados Relatados pelo Paciente
17.
Nat Mater ; 22(8): 1022-1029, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37349398

RESUMO

In analogy to natural enzymes, an elaborated design of catalytic systems with a specifically tailored local chemical environment could substantially improve reaction kinetics, effectively combat catalyst poisoning effect and boost catalyst lifetime under unfavourable reaction conditions. Here we report a unique design of 'Ni(OH)2-clothed Pt-tetrapods' with an amorphous Ni(OH)2 shell as a water dissociation catalyst and a proton conductive encapsulation layer to isolate the Pt core from bulk alkaline electrolyte while ensuring efficient proton supply to the active Pt sites. This design creates a favourable local chemical environment to result in acidic-like hydrogen evolution reaction kinetics with a lowest Tafel slope of 27 mV per decade and a record-high specific activity and mass activity in alkaline electrolyte. The proton conductive Ni(OH)2 shell can also effectively reject impurity ions and retard the Oswald ripening, endowing a high tolerance to solution impurities and exceptional long-term durability that is difficult to achieve in the naked Pt catalysts. The markedly improved hydrogen evolution reaction activity and durability in an alkaline medium promise an attractive catalyst material for alkaline water electrolysers and renewable chemical fuel generation.

18.
Clin Transl Oncol ; 25(10): 2938-2949, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37017923

RESUMO

Renal cell carcinoma (RCC) with poor prognosis and high incidence rate is a common malignant disease. Current therapies could bring little benefit for the patients with advanced-stage RCC. PDIA2 is an isomerase responsible for protein folding and its role in cancer including RCC is under investigation. In this study, we found that PDIA2 was expressed much higher in RCC tissues than the control but the methylation level of PDIA2 promoter was lower based on the TCGA data. Patients with higher PDIA2 expression exerted worse survival. In clinical specimen, PDIA2 expression was correlated to patients' clinical factors such as TNM stage (I/II vs III/IV, p = 0.025) and tumor size (≤ 7 cm vs > 7 cm, p = 0.004). Moreover, K-M analysis showed that PDIA2 was associated with patients' survival in RCC. PDIA2 was expressed much higher in cancer cells A498 than 786-O than that in 293 T cells. After PDIA2 was knocked down, cell proliferation, migration and invasion was potently inhibited. But cell apoptotic rate increased reversely. Furthermore, the efficacy of Sunitinib on RCC cells was strengthened after PDIA2 knockdown. In addition, knockdown of PDIA2 gene leaded to downregulation of levels of JNK1/2, phosphorylated JNK1/2, c-JUN, and Stat3. But this inhibition was partially released when JNK1/2 was overexpressed. In consistent, cell proliferation was also partially recovered. In summary, PDIA2 plays important role in progression of RCC and JNK signaling pathway might be regulated by PDIA2. This study suggests PDIA2 as a candidate target for therapy of RCC.


Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Humanos , Carcinoma de Células Renais/patologia , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Neoplasias Renais/patologia , Sistema de Sinalização das MAP Quinases , Prognóstico
19.
Front Plant Sci ; 14: 1120202, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36937995

RESUMO

Accurate estimations of forest evapotranspiration (ET) and its components, transpiration (T) and evaporation (E), are important for deep understanding and predicting the responses of forest water cycles to climate change. In this study, the improved Shuttleworth-Wallace model (SWH) was applied to estimate ET, T, and E during 2003-2014 in a subtropical planation, and the modeled results were verified using in situ measurements by the eddy covariance technique, sap flow, and micro-lysimeter method. The study aimed to clarify whether it is feasible and reliable to use the SWH model to estimate and partition ET in forests. In addition, depending on the long-term data, the specific performances in modeling ET under different climatic backgrounds were investigated, and the underlying mechanisms were explored. The results verified that the SWH performed relatively well in the subtropical forest, and the modeled ET, T and E could track the seasonal variations, although overestimations were found in the peak seasons. However, the model was relatively weaker in estimating the interannual variabilities. It performed well in modeling ET in normal years but showed larger model residuals in years with obvious climatic anomalies. In the severe summer-drought (2003) and cold-spring (2005) years, the model greatly overestimated ET. It also overestimated ET in summer since 2010, which may be ascribed to the less dependency of ET on VPD induced by the more humid microclimate in forest accompanied with forest development. For the ET partitioning results, the modeled and measured E and T values were all in reasonable ranges. The possible reasons for underestimations (overestimations) of E and T by measurements (SWH model) were discussed. In this study, the data obtained using different methods and from different scales matched each other and could be cross validated, and the discussion on discrepancies would be beneficial for understanding the advantages and flaws of different methods and could be the basis for optimizing the measurement and model methods. In sum, this study verified that it is feasible to use the SWH model in forests and provided a basis for further improving and optimizing the modeled results under different climate backgrounds.

20.
Nano Lett ; 23(7): 2758-2763, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-36971471

RESUMO

Periodic assembly of heterogeneous nanoparticles provides a strategy for integrating distinct nanocatalyst blocks where their synergic effects can be explored for diverse applications. To achieve the synergistic enhancement, an intimate clean interface is preferred which however is usually plagued by the bulky surfactant molecules used in the synthesis and assembly process. Herein, we showed the creation of one-dimensional Pt-Au nanowires (NWs) with periodic alternating Pt and Au nanoblocks, by assembling Pt-Au Janus nanoparticles with the assistance of peptide T7 (Ac-TLTTLTN-CONH2). It is demonstrated that the Pt-Au NWs showed much-improved performance in the methanol oxidation reaction (MOR), exhibiting 5.3 times higher specific activity and 2.5 times higher mass activity than the current state-of-the-art commercial Pt/C catalyst. In addition, the periodic heterostructure also improves the stability of Pt-Au NWs in the MOR, where the Pt-Au NWs retained 93.9% of their initial mass activity much higher than commercial Pt/C (30.6%).

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...