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1.
J Am Chem Soc ; 146(18): 12538-12546, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38656110

RESUMO

There is growing acknowledgment that the properties of the electrochemical interfaces play an increasingly pivotal role in improving the performance of the hydrogen evolution reaction (HER). Here, we present, for the first time, direct dynamic spectral evidence illustrating the impact of the interaction between interfacial water molecules and adsorbed hydroxyl species (OHad) on the HER properties of Ni(OH)2 using Au/core-Ni(OH)2/shell nanoparticle-enhanced Raman spectroscopy. Notably, our findings highlight that the interaction between OHad and interfacial water molecules promotes the formation of weakly hydrogen-bonded water, fostering an environment conducive to improving the HER performance. Furthermore, the participation of OHad in the reaction is substantiated by the observed deprotonation step of Au@2 nm Ni(OH)2 during the HER process. This phenomenon is corroborated by the phase transition of Ni(OH)2 to NiO, as verified through Raman and X-ray photoelectron spectroscopy. The significant redshift in the OH-stretching frequency of water molecules during the phase transition confirms that surface OHad disrupts the hydrogen-bond network of interfacial water molecules. Through manipulation of the shell thickness of Au@Ni(OH)2, we additionally validate the interaction between OHad and interfacial water molecules. In summary, our insights emphasize the potential of electrochemical interfacial engineering as a potent approach to enhance electrocatalytic performance.

2.
Anal Chem ; 96(10): 4275-4281, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38409670

RESUMO

Surface-enhanced Raman scattering (SERS) can overcome the existing technological limitations, such as complex processes and harsh conditions in gaseous small-molecule detection, and advance the development of real-time gas sensing at room temperature. In this study, a SERS-based hydrogen bonding induction strategy for capturing and sensing gaseous acetic acid is proposed for the detection demands of gaseous acetic acid. This addresses the challenges of low adsorption of gaseous small molecules on SERS substrates and small Raman scattering cross sections and enables the first SERS-based detection of gaseous acetic acid by a portable Raman spectrometer. To provide abundant hydrogen bond donors and acceptors, 4-mercaptobenzoic acid (4-MBA) was used as a ligand molecule modified on the SERS substrate. Furthermore, a sensing chip with a low relative standard deviation (RSD) of 4.15% was constructed, ensuring highly sensitive and reliable detection. The hydrogen bond-induced acetic acid trapping was confirmed by experimental spectroscopy and density functional theory (DFT). In addition, to achieve superior accuracy compared to conventional methods, an innovative analytical method based on direct response hydrogen bond formation (IO-H/Iref) was proposed, enabling the detection of gaseous acetic acid at concentrations as low as 60 ppb. The strategy demonstrated a superior anti-interference capability in simulated breath and wine detection systems. Moreover, the high reusability of the chip highlights the significant potential for real-time sensing of gaseous acetic acid.

3.
Anal Chem ; 96(17): 6784-6793, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38632870

RESUMO

Hepatitis B virus (HBV) is a major cause of liver cirrhosis and hepatocellular carcinoma, with HBV surface antigen (HBsAg) being a crucial marker in the clinical detection of HBV. Due to the significant harm and ease of transmission associated with HBV, HBsAg testing has become an essential part of preoperative assessments, particularly for emergency surgeries where healthcare professionals face exposure risks. Therefore, a timely and accurate detection method for HBsAg is urgently needed. In this study, a surface-enhanced Raman scattering (SERS) sensor with a sandwich structure was developed for HBsAg detection. Leveraging the ultrasensitive and rapid detection capabilities of SERS, this sensor enables quick detection results, significantly reducing waiting times. By systematically optimizing critical factors in the detection process, such as the composition and concentration of the incubation solution as well as the modification conditions and amount of probe particles, the sensitivity of the SERS immune assay system was improved. Ultimately, the sensor achieved a sensitivity of 0.00576 IU/mL within 12 min, surpassing the clinical requirement of 0.05 IU/mL by an order of magnitude. In clinical serum assay validation, the issue of false positives was effectively addressed by adding a blocker. The final sensor demonstrated 100% specificity and sensitivity at the threshold of 0.05 IU/mL. Therefore, this study not only designed an ultrasensitive SERS sensor for detecting HBsAg in actual clinical serum samples but also provided theoretical support for similar systems, filling the knowledge gap in existing literature.


Assuntos
Antígenos de Superfície da Hepatite B , Análise Espectral Raman , Antígenos de Superfície da Hepatite B/sangue , Análise Espectral Raman/métodos , Humanos , Vírus da Hepatite B/isolamento & purificação , Nanopartículas Metálicas/química , Hepatite B/sangue , Hepatite B/diagnóstico , Propriedades de Superfície , Limite de Detecção
4.
Small ; : e2311393, 2024 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-38287737

RESUMO

Electrolyte plays a crucial role in ensuring stable operation of lithium metal batteries (LMBs). Localized high-concentration electrolytes (LHCEs) have the potential to form a robust solid-electrolyte interphase (SEI) and mitigate Li dendrite growth, making them a highly promising electrolyte option. However, the principles governing the selection of diluents, a crucial component in LHCE, have not been clearly determined, hampering the advancement of such a type of electrolyte systems. Herein, the diluents from the perspective of molecular polarity are rationally designed and developed. A moderately fluorinated solvent, 1-(1,1,2,2-tetrafluoroethoxy)propane (TNE), is employed as a diluent to create a novel LHCE. The unique molecular structure of TNE enhances the intrinsic dipole moment, thereby altering solvent interactions and the coordination environment of Li-ions in LHCE. The achieved solvation structure not only enhances the bulk properties of LHCE, but also facilitates the formation of more stable anion-derived SEIs featured with a higher proportion of inorganic species. Consequently, the corresponding full cells of both Li||LiFePO4 and Li||LiNi0.8 Co0.1 Mn0.1 O2 cells utilizing Li thin-film anodes exhibit extended long-term stability with significantly improved average Coulombic efficiency. This work offers new insights into the functions of diluents in LHCEs and provides direction for further optimizing the LHCEs for LMBs.

5.
J Chem Phys ; 161(2)2024 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-38973762

RESUMO

Electrocatalytic CO2 reduction reaction (CO2RR) for CH4 production presents a promising strategy to address carbon neutrality, and the incorporation of a second metal has been proven effective in enhancing catalyst performance. Nevertheless, there remains limited comprehension regarding the fundamental factors responsible for the improved performance. Herein, the critical role of Pd in electrocatalytic CO2 reduction to CH4 on Cu-based catalysts has been revealed at a molecular level using in situ surface-enhanced Raman spectroscopy (SERS). A "borrowing" SERS strategy has been developed by depositing Cu-Pd overlayers on plasmonic Au nanoparticles to achieve the in situ monitoring of the dynamic change of the intermediate during CO2RR. Electrochemical tests demonstrate that Pd incorporation significantly enhances selectivity toward CH4 production, and the Faradaic efficiency (FE) of CH4 is more than two times higher than that for the catalysts without Pd. The key intermediates, including *CO2-, *CO, and *OH, have been directly identified under CO2RR conditions, and their evolution with the electrochemical environments has been determined. It is found that Pd incorporation promotes the activation of both CO2 and H2O molecules and accelerates the formation of abundant active *CO and hydrogen species, thus enhancing the CH4 selectivity. This work offers fundamental insights into the understanding of the molecular mechanism of CO2RR and opens up possibilities for designing more efficient electrocatalysts.

6.
Nano Lett ; 21(11): 4708-4714, 2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34014682

RESUMO

Efficient propagation of spin waves in a magnetically coupled vortex is crucial to the development of future magnonic devices. Thus far, only a double vortex can serve as spin-wave emitter or oscillator; the propagation of spin waves in the higher-order vortex is still lacking. Here, we experimentally realize a higher-order vortex (2D vortex network) by a designed nanostructure, containing four cross-type chiral substructures. We employ this vortex network as a waveguide to propagate short-wavelength spin waves (∼100 nm) and demonstrate the possibility of guiding spin waves from one vortex to the network. It is observed that the spin waves can propagate into the network through the nanochannels formed by the Bloch-Néel-type domain walls, with a propagation decay length of several micrometers. This technique paves the way for the development of low-energy, reprogrammable, and miniaturized magnonic devices.

7.
BMC Infect Dis ; 20(1): 695, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32962639

RESUMO

BACKGROUND: With the widespread outbreak of novel coronavirus diseases 2019(COVID-19), more and more death cases were reported, however, limited data are available for the patients who died. We aimed to explore the clinical characteristics of deaths with COVID-19 pneumonia. METHODS: We abstracted and analyzed epidemiological, demographic, clinical, and laboratory data from 83 death cases with COVID-19 pneumonia in East Hospital of Wuhan University Renmin Hospital, between January 26, 2020, and February 28, 2020. RESULTS: Of the 83 deaths, none was the medical staff. The mean age was 71.8 years (SD 13.2; range, 34-97 years) and 53(63.9%) were male. The median from onset to admission was 10 days (IQR 7-14: range, 2-43 days), to death was 17 days (IQR 14-21: range, 6-54 days). Most deaths (66[80%]) had underlying comorbid diseases, the most of which was hypertension [47(57%)]. The main initial symptoms of these 83 deaths were shortness of breath(98.8%), fever(94%), and myalgia or fatigue(90.4%). Laboratory analyses showed the lymphocytopenia in 69(83%) deaths, hypoalbuminemia in 77(93%) deaths, the elevation of lactate dehydrogenase in 79(95%) deaths, procalcitonin in 69(83%) deaths and C-reactive protein in 79(95%) deaths. All 83 patients received antiviral treatment, 81(97.6%) deaths received antibiotic therapy, 54(65.1%) deaths received glucocorticoid therapy, and 20(24.1%) patients received invasive mechanical ventilation. CONCLUSION: Most of the deaths with COVID-19 pneumonia were elderly patients with underlying comorbid diseases, especially those over 70 years of age. The time of death after the onset of the disease was mostly 15-21 days. More care should be given to the elderly in further prevention and control strategies of COVID-19.


Assuntos
Infecções por Coronavirus/mortalidade , Pneumonia Viral/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Antivirais/uso terapêutico , Betacoronavirus , Proteína C-Reativa/análise , COVID-19 , China/epidemiologia , Infecções por Coronavirus/terapia , Fadiga , Feminino , Febre/virologia , Glucocorticoides/uso terapêutico , Hospitalização , Humanos , Hipertensão/complicações , L-Lactato Desidrogenase/sangue , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/terapia , Pró-Calcitonina/sangue , Respiração Artificial , Estudos Retrospectivos , SARS-CoV-2
8.
Chem Soc Rev ; 48(22): 5432-5453, 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31647083

RESUMO

The lithium-sulfur (Li-S) battery is one of the most promising high-energy-density secondary battery systems. However, it suffers from issues arising from its extremely complicated "solid-liquid-solid" reaction routes. In recent years, enormous advances have been made in optimizing Li-S batteries via the rational design of compositions and architectures. Nevertheless, a comprehensive and in-depth understanding of the practical reaction mechanisms of Li-S systems and their effect on the electrochemical performance is still lacking. Very recently, several important in situ optical spectroscopic techniques, including Raman, infrared and ultraviolet-visible spectroscopies, have been developed to monitor the real-time variations of the battery states, and a bridge linking the macroscopic electrochemical performance and microscopic architectures of the components has been set up, thus playing a critical role in scientifically guiding further optimal design of Li-S batteries. In this tutorial review, we provide a systematic summary of the state-of-the-art innovations in the characterization and optimal design of Li-S batteries with the aid of these in situ optical spectroscopic techniques, to guide a beginner to construct in situ optical spectroscopy electrochemical cells, and develop strategies for preventing long-chain polysulfide formation, dissolution and migration, thus alleviating the shuttle effect in Li-S batteries and improving the cell performances significantly.

9.
Small ; : e1801536, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-30028569

RESUMO

Binders have been considered to play a key role in realizing high-energy-density lithium-sulfur batteries. However, the accompanying problems of limited conductivity and inferior affinity of soluble polysulfide intermediates bring down their comprehensive performance for practical applications. Herein, the synthesis of a novel double-chain polymer network (DCP) binder by polymerizing 4,4'-biphenyldisulfonic acid connected pyrrole monomer onto viscous sodium carboxymethyl cellulose matrix, yielding a primary crystal structure is reported. Consequently, the resulted binder enables superior rate performance from 0.2 C (1326.9 mAh g-1 ) to 4 C (701.4 mAh g-1 ). Moreover, a high sulfur loading of 9.8 mg cm-2 and a low electrolyte/sulfur ratio (5:1, µL mg-1 ) are achieved, exhibiting a high area capacity of 9.2 mAh cm-2 . In situ X-ray diffraction analysis is conducted to monitor the structural modifications of the cathode, confirming the occurrence of sulfur reduction/recrystallization during charge-discharge process. In addition, in situ UV-vis measurements demonstrate that DCP binder impedes the polysulfide migration, thereby giving rise to high capacity retention for 400 cycles.

10.
ACS Appl Mater Interfaces ; 16(10): 12149-12160, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38412551

RESUMO

Photocatalysis driven by plasmon-induced hot carriers has been gaining increasing attention. Recent studies have demonstrated that plasmon-induced hot carriers can directly participate in photocatalytic reactions, leading to great enhancement in solar energy conversion efficiency, by improving the catalytic activity or changing selectivity. Nevertheless, the utilization efficiency of hot carriers remains unsatisfactory. Therefore, how to correctly understand the generation and transfer process of hot carriers, as well as accurately differentiate between the possible mechanisms, have become a key point of attention. In this review, we overview the fundamental processes and mechanisms underlying hot carrier generation and transport, followed by highlighting the importance of hot carrier monitoring methods and related photocatalytic reactions. Furthermore, possible strategies for the further characterization of plasmon-induced hot carriers and boosting their utilization efficiency have been proposed. We hope that a comprehensive understanding of the fundamental behaviors of hot carriers can aid in designing more efficient photocatalysts for plasmon-induced photocatalytic reactions.

11.
J Colloid Interface Sci ; 660: 916-922, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38280284

RESUMO

Intermetallic compounds are emerging as promising oxygen reduction reaction (ORR) catalysts for fuel cells due to their typically higher activity and durability compared to disordered alloys. However, the preparation of intermetallic catalysts often requires high-temperature annealing, which unfortunately leads to adverse sintering of the metal nanoparticles. Herein, we develop a scalable site-selective sulfur anchoring strategy that effectively suppresses alloy sintering, ensuring the formation of efficient intermetallic electrocatalysts with small sizes and high ordering degrees. The alloy-support interactions are precisely modulated by selectively modifying the alloy-support interfaces with oxidized sulfur species, thus simultaneously blocking both the nanoparticle migration and Oswald ripening pathways for sintering. Using this strategy, sub-5 nm PtCo intermetallic electrocatalysts enclosed by two atomic layers of Pt shells have been successfully prepared even at a metal loading higher than 30 wt%. The intermetallic catalysts exhibit excellent ORR performances in both rotating disk electrode and membrane electrode assembly conditions with a mass activity of 1.28 A mgPt-1 at 0.9 V (vs. RHE) and a power density of 1.0 W cm-2 at a current density of 1.5 A cm-2. The improved performances result from the enhanced Pt-Co electronic interactions and compressive surface strain generated by the highly ordering structure, while the atomic Pt shells prevent the dissolution of Co under highly acidic conditions. This work provides new insights to inhibit the sintering of nanoalloys and would promote the scalable synthesis and applications of platinum-based intermetallic catalysts.

12.
J Fungi (Basel) ; 9(10)2023 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-37888215

RESUMO

Grifola frondosa is a valuable edible fungus with high nutritional and medicinal values. The mating systems of fungi not only offer practical strategies for breeding, but also have far-reaching effects on genetic variability. Grifola frondosa has been considered as a sexual species with a tetrapolar mating system based on little experimental data. In the present study, one group of test crosses and six groups of three-round mating experiments from two parental strains were conducted to determine the mating system in G. frondosa. A chi-squared test of the results of the test-cross mating experiments indicated that they satisfied Mendelian segregation, while a series of three-round mating experiments showed that Mendelian segregation was not satisfied, implying a segregation distortion phenomenon in G. frondosa. A genomic map of the G. frondosa strain, y59, grown from an LMCZ basidiospore, with 40.54 Mb and 12 chromosomes, was generated using genome, transcriptome and Hi-C sequencing technology. Based on the genomic annotation of G. frondosa, the mating-type loci A and B were located on chromosomes 1 and 11, respectively. The mating-type locus A coded for the ß-fg protein, HD1, HD2 and MIP, in that order. The mating-type locus B consisted of six pheromone receptors (PRs) and five pheromone precursors (PPs) in a crossed order. Moreover, both HD and PR loci may have only one sublocus that determines the mating type in G. frondosa. The nonsynonymous SNP and indel mutations between the A1B1 and A2B2 mating-type strains and the reference genome of y59 only occurred on genes HD2 and PR1/2, preliminarily confirming that the mating type of the y59 strain was A1B2 and not A1B1. Based on the genetic evidence and the more reliable molecular evidence, the results reveal that the mating system of G. frondosa is tetrapolar. This study has important implications for the genetics and hybrid breeding of G. frondosa.

13.
Nanomicro Lett ; 16(1): 53, 2023 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-38108934

RESUMO

Interfacial water molecules are the most important participants in the hydrogen evolution reaction (HER). Hence, understanding the behavior and role that interfacial water plays will ultimately reveal the HER mechanism. Unfortunately, investigating interfacial water is extremely challenging owing to the interference caused by bulk water molecules and complexity of the interfacial environment. Here, the behaviors of interfacial water in different cationic electrolytes on Pd surfaces were investigated by the electrochemistry, in situ core-shell nanostructure enhanced Raman spectroscopy and theoretical simulation techniques. Direct spectral evidence reveals a red shift in the frequency and a decrease in the intensity of interfacial water as the potential is shifted in the positively direction. When comparing the different cation electrolyte systems at a given potential, the frequency of the interfacial water peak increases in the specified order: Li+ < Na+ < K+ < Ca2+ < Sr2+. The structure of interfacial water was optimized by adjusting the radius, valence, and concentration of cation to form the two-H down structure. This unique interfacial water structure will improve the charge transfer efficiency between the water and electrode further enhancing the HER performance. Therefore, local cation tuning strategies can be used to improve the HER performance by optimizing the interfacial water structure.

14.
J Colloid Interface Sci ; 650(Pt B): 1518-1524, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37487282

RESUMO

Palladium-based nanocatalysts play an important role in catalyzing the cathode oxygen reduction reaction (ORR) for fuel cells working under alkaline conditions, but the performance still needs to be improved to meet the requirements for large-scale applications. Herein, Au@Pd core-shell nanowires have been developed by coating Pd atomic layers on ultrafine gold nanowires and display outstanding electrocatalytic performance towards alkaline ORR. It is found that Pd overlayers with atomic thickness can be coated on 3 nm Au nanowires under CO atmosphere and completely cover the surfaces. The obtained ultrafine Au@Pd nanowires exhibit an electrochemical active area (ECSA) of 68.5 m2/g and a mass activity of 0.91 A/mg (at 0.9 V vs. RHE), which is around 3.1 and 15.2 times higher than that of commercial Pd/C. The activity loss of the ultrafine Au@Pd nanowire after 10,000 cycles of accelerated degradation tests is only ∼20 %, demonstrating its much better stability compared to commercial Pd/C. Further characterizations combined with density functional theory (DFT) calculations demonstrate that the electronic interactions between Pd atomic layers and underlying Au can increase the electronic density of Pd and promote the efficient activation of oxygen, thus leading to the improved ORR performance.

15.
Small Methods ; : e2301504, 2023 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-38148311

RESUMO

Developing efficient oxygen evolution reaction (OER) electrocatalysts can greatly advance the commercialization of proton exchange membrane (PEM) water electrolysis. However, the unclear and disputed reaction mechanism and structure-activity relationship of OER pose significant obstacles. Herein, the active site and intermediate for OER on AuIr nanoalloys are simultaneously identified and correlated with the activity, through the integration of in situ shell-isolated nanoparticle-enhanced Raman spectroscopy and X-ray absorption spectroscopy. The AuIr nanoalloys display excellent OER performance with an overpotential of only 246 mV to achieve 10 mA cm-2 and long-term stability under strong acidic conditions. Direct spectroscopic evidence demonstrates that * OO adsorbed on IrOx sites is the key intermediate for OER, and it is generated through the O-O coupling of adsorbed oxygen species directly from water, providing clear support for the adsorbate evolution mechanism. Moreover, the Raman information of the * OO intermediate can serve as a universal "in situ descriptor" that can be obtained both experimentally and theoretically to accelerate the catalyst design. It unveils that weakening the interactions of * OO on the catalysts and facilitating its desorption would boost the OER performance. This work deepens the mechanistic understandings on OER and provides insightful guidance for the design of more efficient OER catalysts.

16.
Electrophoresis ; 32(22): 3201-6, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22038673

RESUMO

This article describes the fabrication of tube-like microchannels made of UV curable polymer on a glass substrate and the device assembling with a disposable enzyme-working electrode for high-sensitivity electrochemical detection. While both reference and counter electrodes are patterned on the surface of the glass substrate, the working electrode is flipped on the top of the channel with an open access, providing a face-to-face probing configuration. When the enzyme electrode is contaminated or degraded, it can be easily replaced by a new one, keeping the main body of the device and the detection schema unchanged. Using glucose oxidase-coated gold electrodes, we were able to determine a linear amperometry response to the glucose concentrations in the range of 2-16 mM. By replacing the as-prepared working electrode by the one after thermal treatments, we showed a much more degraded enzyme electrode activity, enabling efficient determination of the electrode quality as well as the whole process optimization.


Assuntos
Técnicas Biossensoriais/instrumentação , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/metabolismo , Glucose/análise , Técnicas Analíticas Microfluídicas/instrumentação , Enzimas Imobilizadas/química , Desenho de Equipamento , Glucose Oxidase/química , Técnicas Analíticas Microfluídicas/métodos
17.
Langmuir ; 27(11): 6549-53, 2011 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-21539351

RESUMO

Herein we report the fabrication of ZnO nanowires on anisotropic wet etched silicon substrates by selective hydrothermal growth. <100> oriented silicon wafers were first patterned by anisotropic wet etch with a KOH solution, resulting in V-shaped stripes of different periods. Then, a thin layer of gold was deposited and annealed to promote the hydrothermal growth of ZnO nanowires. It was found that the growth rate of ZnO nanowires on <111> surfaces was much higher than that on <100> surfaces. As a first application of such micro- and nanostructured surfaces, we show enhanced wetting properties by measuring the contact angle of water droplets on the samples obtained under different patterning and growth conditions. Our results also demonstrated the possibility of tuning the contact angle of the sample in the range between 115° and 155°, by changing either the pattern of the silicon template or the hydrothermal growth conditions.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Nanotecnologia/métodos , Nanofios/química , Silício/química , Óxido de Zinco/química , Anisotropia , Propriedades de Superfície
18.
Nanotechnology ; 22(24): 245601, 2011 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-21508463

RESUMO

Seedless hydrothermal synthesis has been improved by introducing an adequate content of ammonia into the nutrient solution, allowing the fabrication of dense and ultralong ZnO nanowire arrays over large areas on a substrate. The presence of ammonia in the nutrient solution facilitates the high density nucleation of ZnO on the substrate which is critical for the nanowire growth. In order to achieve an optimal growth, the growth conditions have been studied systematically as a function of ammonia content, growth temperature and incubation time. The effect of polyethyleneimine (PEI) has also been studied but shown to be of no benefit to the nucleation of ZnO. Ultradense and ultralong ZnO nanowires could be obtained under optimal growth conditions, showing no fused structure at the foot of the nanowire arrays. Due to different reaction kinetics, four growth regimes could be attributed, including the first fast growth, equilibrium phase, second fast growth and final erosion. Combining this simple method with optical lithography, ZnO nanowires could be grown selectively on patterned areas. In addition, the as-grown ZnO nanowires could be used for the fabrication of a piezoelectric nanogenerator. Compared to the device of ZnO nanowires made by other methods, a more than twice voltage output has been obtained, thereby proving an improved performance of our growth method.

19.
Nanotechnology ; 22(27): 275313, 2011 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-21613733

RESUMO

This work presents a study of Au conductance quantization based on a combined electrochemical deposition and mechanically controllable break junction (MCBJ) method. We describe the microfabrication process and discuss improved features of our microchip structure compared to the previous one. The improved structure prolongs the available life of the microchip and also increases the success rate of the MCBJ experiment. Stepwise changes in the current were observed at the last stage of atomic point contact breakdown and conductance histograms were constructed. The evolution of 1G0 peak height in conductance histograms was used to investigate the probability of formation of an atomic point contact. It has been shown that the success rate in forming an atomic point contact can be improved by decreasing the stretching speed and the degree that the two electrodes are brought into contact. The repeated breakdown and formation over thousands of cycles led to a distinctive increase of 1G0 peak height in the conductance histograms, and this increased probability of forming a single atomic point contact is discussed.

20.
Biomed Pharmacother ; 133: 111028, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33378943

RESUMO

Aspirin is one of the most commonly prescribed medications. Evidence shows that it can even treat and prevent intestinal tumors. However, it has also caused a great deal of controversy due to its intestinal side effects. We therefore explored whether aspirin was beneficial or harmful to the intestines. We used aspirin continuously interfered with C57BL/6 J mice for 48 weeks, examining their intestinal tissues at 13, 26 and 48 weeks to determine the drug's effect on the intestines. In addition, we used flow cytometry (FCM) used to detect T cells and expression of T-cell immunoreceptor with immunoglobulin (Ig)- and tyrosine-based inhibitory motif (ITIM) domain (TIGIT) on their surfaces to determine aspirin's immunomodulatory effects. The results showed that long-term aspirin intervention could reverse damage to the intestines, an effect related to the drug's significant inhibitory effect on TIGIT. The change in TIGIT level could regulate T-cell subsets, so that counts of Cluster of Differentiation 4 (CD4)+/chemokine (C-X3-C motif) receptor 3 (CXCR3)+ T-helper 1 (Th1) cells and CD4+/interleukin-4 (IL-4)+ Th2 cells increased, while those of CD4+/C-C chemokine receptor type 6 (CCR6)+ Th17 cells and CD4+/CD25+ regulatory T cells (Tregs) decreased. In summary, we demonstrated that long-term aspirin intervention could inhibit TIGIT, regulating T cells to reverse damage to the intestines. Furthermore, aspirin is a potential therapy for diseases related to an increase in TIGIT.


Assuntos
Aspirina/toxicidade , Colo/efeitos dos fármacos , Receptores Imunológicos/metabolismo , Reto/efeitos dos fármacos , Subpopulações de Linfócitos T/efeitos dos fármacos , Animais , Colo/imunologia , Colo/metabolismo , Colo/patologia , Regulação para Baixo , Masculino , Camundongos Endogâmicos C57BL , Fenótipo , Reto/imunologia , Reto/metabolismo , Reto/patologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Células Th1/efeitos dos fármacos , Células Th1/imunologia , Células Th1/metabolismo , Células Th17/efeitos dos fármacos , Células Th17/imunologia , Células Th17/metabolismo , Células Th2/efeitos dos fármacos , Células Th2/imunologia , Células Th2/metabolismo , Fatores de Tempo
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