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1.
J Vis Exp ; (206)2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38738889

RESUMO

Follicular Helper T (TFH) cells are perceived as an independent CD4+ T cell lineage that assists cognate B cells in producing high-affinity antibodies, thus establishing long-term humoral immunity. During acute viral infection, the fate commitment of virus-specific TFH cells is determined in the early infection phase, and investigations of the early-differentiated TFH cells are crucial in understanding T cell-dependent humoral immunity and optimizing vaccine design. In the study, using a mouse model of acute lymphocytic choriomeningitis virus (LCMV) infection and the TCR-transgenic SMARTA (SM) mouse with CD4+ T cells specifically recognizing LCMV glycoprotein epitope I-AbGP66-77, we described procedures to access the early fate commitment of virus-specific TFH cells based on flow cytometry stainings. Furthermore, by exploiting retroviral transduction of SM CD4+ T cells, methods to manipulate gene expression in early-differentiated virus-specific TFH cells are also provided. Hence, these methods will help in studies exploring the mechanism(s) underlying the early commitment of virus-specific TFH cells.


Assuntos
Linfócitos T CD4-Positivos , Diferenciação Celular , Coriomeningite Linfocítica , Animais , Camundongos , Linfócitos T CD4-Positivos/imunologia , Diferenciação Celular/imunologia , Citometria de Fluxo/métodos , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/virologia , Vírus da Coriomeningite Linfocítica/imunologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Células T Auxiliares Foliculares/imunologia , Linfócitos T Auxiliares-Indutores/imunologia
2.
Angew Chem Int Ed Engl ; : e202406795, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38708785

RESUMO

The accumulation of plastic waste poses a pressing environmental challenge. Catalytic conversion stands out as an ideal approach for plastics upcycling, particularly through solar-driven plastics photoreforming. However, due to the common effects of multiple reactive oxygen species (ROS), selectively generating high-value chemicals becomes challenging. In this study, we developed a universal strategy to achieve >85 % selective production of diesel olefins (C15-C28) from polyolefin waste plastics via single ROS. Using tetrakis (4-carboxyphenyl) porphyrin supramolecular (TCPP) with different central metals as an example to regulate single ROS generation, results show Ni-TCPP facilitates triplet exciton production, yielding 1O2, while Zn-TCPP generates ⋅O2 - due to its strong built-in electric field (IEF). 1O2 directly dechlorinates polyvinyl chloride (PVC) due to the electro-negativity of chlorine atoms and the low dissociation energy of C-Cl bonds, while ⋅O2 - promotes direct dehydrogenation of polyethylene (PE) due to the electro-positivity of hydrogen atoms and the high dissociation energy of C-H bonds. This method is universally applicable to various single ROS systems. Installation experiments further affirm the application potential, achieving the highest diesel olefin production of 76.1 µmol h-1. Such a universally adaptive approach holds promise for addressing the global plastic pollution problem.

3.
Nat Cancer ; 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38609488

RESUMO

Tumor-specific T cells are crucial in anti-tumor immunity and act as targets for cancer immunotherapies. However, these cells are numerically scarce and functionally exhausted in the tumor microenvironment (TME), leading to inefficacious immunotherapies in most patients with cancer. By contrast, emerging evidence suggested that tumor-irrelevant bystander T (TBYS) cells are abundant and preserve functional memory properties in the TME. To leverage TBYS cells in the TME to eliminate tumor cells, we engineered oncolytic virus (OV) encoding TBYS epitopes (OV-BYTE) to redirect the antigen specificity of tumor cells to pre-existing TBYS cells, leading to effective tumor inhibition in multiple preclinical models. Mechanistically, OV-BYTE induced epitope spreading of tumor antigens to elicit more diverse tumor-specific T cell responses. Remarkably, the OV-BYTE strategy targeting human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cell memory efficiently inhibited tumor progression in a human tumor cell-derived xenograft model, providing important insights into the improvement of cancer immunotherapies in a large population with a history of SARS-CoV-2 infection or coronavirus disease 2019 (COVID-19) vaccination.

4.
Nat Commun ; 15(1): 1893, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38424438

RESUMO

Exciton transport in two-dimensional Ruddlesden-Popper perovskite plays a pivotal role for their optoelectronic performance. However, a clear photophysical picture of exciton transport is still lacking due to strong confinement effects and intricate exciton-phonon interactions in an organic-inorganic hybrid lattice. Herein, we present a systematical study on exciton transport in (BA)2(MA)n-1PbnI3n+1 Ruddlesden-Popper perovskites using time-resolved photoluminescence microscopy. We reveal that the free exciton mobilities in exfoliated thin flakes can be improved from around 8 cm2 V-1 s-1 to 280 cm2V-1s-1 by anchoring the soft butyl ammonium cation with a polymethyl methacrylate network at the surface. The mobility of the latter is close to the theoretical limit of Mott-Ioffe-Regel criterion. Combining optical measurements and theoretical studies, it is unveiled that the polymethyl methacrylate network significantly improve the lattice rigidity resulting in the decrease of deformation potential scattering and lattice fluctuation at the surface few layers. Our work elucidates the origin of high exciton mobility in Ruddlesden-Popper perovskites and opens up avenues to regulate exciton transport in two-dimensional materials.

5.
Chemphyschem ; 25(4): e202300726, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38059760

RESUMO

As a promising strategy to improve photocatalytic efficiency, spin polarization has attracted enormous attention in recent years, which could be involved in various steps of photoreaction. The Pauli repulsion principle and the spin selection rule dictate that the behavior of two electrons in a spatial eigenstate is based on their spin states, and this fact opens up a new avenue for manipulating photocatalytic efficiency. In this review, recent advances in modulating the photocatalytic activity with spin polarization are systematically summarized. Fundamental insights into the influence of spin-polarization effects on photon absorption, carrier separation, and migration, and the behaviors of reaction-related substances from the photon uptake to reactant desorption are highlighted and discussed in detail, and various photocatalytic applications for environmental purification and energy conversion are presented. This review is expected to deliver a timely overview of the recent developments in spin-polarization-modulated photocatalysis for environmental purification and energy conversion in terms of their practical applications.

6.
J Am Heart Assoc ; 12(24): e029571, 2023 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-38063152

RESUMO

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation serves as a crucial mechanical circulatory support for pediatric patients with severe heart diseases, but the mortality rate remains high. The objective of this study was to assess the short-term mortality in these patients. METHODS AND RESULTS: We systematically searched PubMed, Embase, and Cochrane Library for observational studies that evaluated the short-term mortality of pediatric patients undergoing veno-arterial extracorporeal membrane oxygenation. To estimate short-term mortality, we used random-effects meta-analysis. Furthermore, we conducted meta-regression and binomial regression analyses to investigate the risk factors associated with the outcome of interest. We systematically reviewed 28 eligible references encompassing a total of 1736 patients. The pooled analysis demonstrated a short-term mortality (defined as in-hospital or 30-day mortality) of 45.6% (95% CI, 38.7%-52.4%). We found a significant difference (P<0.001) in mortality rates between acute fulminant myocarditis and congenital heart disease, with acute fulminant myocarditis exhibiting a lower mortality rate. Our findings revealed a negative correlation between older age and weight and short-term mortality in patients undergoing veno-arterial extracorporeal membrane oxygenation. Male sex, bleeding, renal damage, and central cannulation were associated with an increased risk of short-term mortality. CONCLUSIONS: The short-term mortality among pediatric patients undergoing veno-arterial extracorporeal membrane oxygenation for severe heart diseases was 45.6%. Patients with acute fulminant myocarditis exhibited more favorable survival rates compared with those with congenital heart disease. Several risk factors, including male sex, bleeding, renal damage, and central cannulation contributed to an increased risk of short-term mortality. Conversely, older age and greater weight appeared to be protective factors.


Assuntos
Oxigenação por Membrana Extracorpórea , Cardiopatias Congênitas , Miocardite , Humanos , Masculino , Criança , Miocardite/etiologia , Cardiopatias Congênitas/etiologia , Hemorragia/etiologia , Taxa de Sobrevida , Estudos Retrospectivos
7.
Angew Chem Int Ed Engl ; 62(47): e202313298, 2023 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-37795962

RESUMO

Peroxymonosulfate (PMS) mediated radical and nonradical active substances can synergistically achieve the efficient elimination of antibiotic resistance genes (ARGs). However, enhancing interface electron cycling and optimizing the coupling of the oxygen-containing intermediates to improve PMS activation kinetics remains a major challenge. Here, Co doped CeVO4 catalyst (Co-CVO) with asymmetric sites was constructed based on Ce 4f-O 2p-Co 3d gradient orbital coupling. The catalyst achieved approximately 2.51×105 copies/mL of extracellular ARGs (eARGs) removal within 15 minutes, exhibited ultrahigh degradation rate (k=1.24 min-1 ). The effective gradient 4f-2p-3d orbital coupling precisely regulates the electron distribution of Ce-O-Co active center microenvironment, while optimizing the electronic structure of Co 3d states (especially the occupancy of eg ), promoting the adsorption of oxygen-containing intermediates. The generated radical and nonradical generated by interfacial electron cycling enhanced by the reduction reaction of PMS at the Ce site and the oxidation reaction at the Co site achieved a significant mineralization rate of ARGs (83.4 %). The efficient removal of ARGs by a continuous flow reactor for 10 hours significantly reduces the ecological risk of ARGs in actual wastewater treatment.


Assuntos
Antibacterianos , Peróxidos , Antibacterianos/farmacologia , Peróxidos/química , Oxirredução , Resistência Microbiana a Medicamentos , Oxigênio
8.
Nutrients ; 15(20)2023 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-37892435

RESUMO

Poria cocos is traditionally used as both food and medicine. Triterpenoids in Poria cocos have a wide range of pharmacological activities, such as diuretic, sedative and tonic properties. In this study, the anti-tumor activities of poricoic acid A (PAA) and poricoic acid B (PAB), purified by high-speed counter-current chromatography, as well as their mechanisms and signaling pathways, were investigated using a HepG2 cell model. After treatment with PAA and PAB on HepG2 cells, the apoptosis was obviously increased (p < 0.05), and the cell cycle arrested in the G2/M phase. Studies showed that PAA and PAB can also inhibit the occurrence and development of tumor cells by stimulating the generation of ROS in tumor cells and inhibiting tumor migration and invasion. Combined Polymerase Chain Reaction and computer simulation of molecular docking were employed to explore the mechanism of tumor proliferation inhibition by PAA and PAB. By interfering with phosphatidylinositol-3-kinase/protein kinase B, Mitogen-activated protein kinases and p53 signaling pathways; and further affecting the expression of downstream caspases; matrix metalloproteinase family, cyclin-dependent kinase -cyclin, Intercellular adhesion molecules-1, Vascular Cell Adhesion Molecule-1 and Cyclooxygenase -2, may be responsible for their anti-tumor activity. Overall, the results suggested that PAA and PAB induced apoptosis, halted the cell cycle, and inhibited tumor migration and invasion through multi-pathway interactions, which may serve as a potential therapeutic agent against cancer.


Assuntos
Proteínas Proto-Oncogênicas c-akt , Triterpenos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Triterpenos/farmacologia , Simulação de Acoplamento Molecular , Simulação por Computador , Proliferação de Células , Transdução de Sinais , Apoptose
9.
Sci Adv ; 9(39): eadi9347, 2023 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-37774031

RESUMO

Phonon-assisted photon upconversion holds great potential for numerous applications, e.g., optical refrigeration. However, traditional semiconductors face energy gain limitations due to thermal energy, typically achieving only ~25 milli-electron volts at room temperature. Here, we demonstrate that quasi-two-dimensional perovskites, with a soft hybrid organic-inorganic lattice, can efficiently upconvert photons with an anti-Stokes shift exceeding 200 milli-electron volts. By using microscopic transient absorption measurements and density functional theory calculations, we explicate that the giant energy gain stems from strong lattice fluctuation leading to a picosecond timescale transient band energy renormalization with a large energy variation of around ±180 milli-electron volts at room temperature. The motion of organic molecules drives the deformation of inorganic framework, providing energy and local states necessary for efficient upconversion within a time constant of around 1 ps. These results establish a deep understanding of perovskite-based photon upconversion and offer previously unknown insights into the development of various upconversion applications.

10.
J Phys Chem Lett ; 14(29): 6702-6708, 2023 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-37467492

RESUMO

The Tauc plot is widely used to determine the bandgap of semiconductors, but the actual plot often exhibits significant baseline absorption below the expected bandgap, leading to bandgap discrepancies from two different extrapolations. In this work, we first discuss the origin of baseline absorption and show that both extrapolation methods can produce significant errors by simulating Tauc plots with varying levels of baseline absorption. We then propose and experimentally verify a new method that idealizes the absorption spectrum by removing its baseline before constructing the Tauc plot. Finally, we apply this new method to cubic boron arsenide (c-BAs), resolve its bandgap discrepancies, and obtain a converging bandgap of 1.835 eV based on both previous and new transmission spectra. The method is applicable to both indirect and direct bandgap semiconductors with absorption spectrum measured via transmission or diffuse reflectance, which will become essential to obtain accurate values of their bandgaps.

11.
Vaccine ; 41(34): 4986-4995, 2023 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-37400286

RESUMO

The COVID-19 vaccinations are crucial in protecting against the global pandemic. However, accumulating studies revealed the severely blunted COVID-19 vaccine effectiveness in cancer patients. The PD-1/PD-L1 immune checkpoint blockade (ICB) therapy leads to durable therapeutic responses in a subset of cancer patients and has been approved to treat a wide spectrum of cancers in the clinic. In this regard, it is pivotal to explore the potential impact of PD-1/PD-L1 ICB therapy on COVID-19 vaccine effectiveness during ongoing malignancy. In this study, using preclinical models, we found that the tumor-suppressed COVID-19 vaccine responses are largely reverted in the setting of PD-1/PD-L1 ICB therapy. We also identified that the PD-1/PD-L1 blockade-directed restoration of COVID-19 vaccine effectiveness is irrelevant to anti-tumor therapeutic outcomes. Mechanistically, the restored COVID-19 vaccine effectiveness is entwined with the PD-1/PD-L1 blockade-driven preponderance of follicular helper T cell and germinal center responses during ongoing malignancy. Thus, our findings indicate that PD-1/PD-L1 blockade will greatly normalize the responses of cancer patients to COVID-19 vaccination, while regardless of its anti-tumor efficacies on these patients.


Assuntos
COVID-19 , Neoplasias , Humanos , Vacinas contra COVID-19 , Inibidores de Checkpoint Imunológico/uso terapêutico , Antígeno B7-H1 , Receptor de Morte Celular Programada 1 , COVID-19/prevenção & controle , Neoplasias/terapia , Imunoterapia
12.
ACS Appl Mater Interfaces ; 15(29): 34797-34808, 2023 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-37433096

RESUMO

InP quantum dots (QDs) are promising building blocks for use in solar technologies because of their low intrinsic toxicity, narrow bandgap, large absorption coefficient, and low-cost solution synthesis. However, the high surface trap density of InP QDs reduces their energy conversion efficiency and degrades their long-term stability. Encapsulating InP QDs into a wider bandgap shell is desirable to eliminate surface traps and improve optoelectronic properties. Here, we report the synthesis of "giant" InP/ZnSe core/shell QDs with tunable ZnSe shell thickness to investigate the effect of the shell thickness on the optoelectronic properties and the photoelectrochemical (PEC) performance for hydrogen generation. The optical results demonstrate that ZnSe shell growth (0.9-2.8 nm) facilitates the delocalization of electrons and holes into the shell region. The ZnSe shell simultaneously acts as a passivation layer to protect the surface of InP QDs and as a spatial tunneling barrier to extract photoexcited electrons and holes. Thus, engineering the ZnSe shell thickness is crucial for the photoexcited electrons and hole transfer dynamics to tune the optoelectronic properties of "giant" InP/ZnSe core/shell QDs. We obtained an outstanding photocurrent density of 6.2 mA cm-1 for an optimal ZnSe shell thickness of 1.6 nm, which is 288% higher than the values achieved from bare InP QD-based PEC cells. Understanding the effect of shell thickness on surface passivation and carrier dynamics offers fundamental insights into the suitable design and realization of eco-friendly InP-based "giant" core/shell QDs toward improving device performance.

13.
Environ Sci Pollut Res Int ; 30(33): 80844-80854, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37308623

RESUMO

Promoting sustainable economic development has been pursued by all countries, and achieving green economic development is crucial to sustainable economic development. This study uses the non-radial direction distance function (NDDF) method to calculate the level of development of the green economy in Chinese cities during 2003-2014. Next, it uses the establishment of China's city commercial banks as an exogenous policy shock to build a staggered difference-in-differences model to empirically test the impact of the establishment of city commercial banks on green economy development. This study found that, first, the establishment of city commercial banks significantly promoted green economy development. Second, in areas with a high proportion of small and medium-sized enterprises (SMEs), the establishment of city commercial banks is imperative to promoting green economy development. SMEs are crucial carriers to city commercial banks to promote green economy development. Third, financing constraints mitigation, green innovation, and pollution emission reduction are important channels for city commercial banks affecting green economy development. This study enriches the relevant research on the impact of financial market reform on green economy development.


Assuntos
Conservação de Recursos Energéticos , Desenvolvimento Econômico , China , Cidades
14.
Nano Lett ; 23(9): 3716-3723, 2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37125916

RESUMO

Out-of-plane (OP) exciton-based emitters in two-dimensional semiconductor materials are attractive candidates for novel photonic applications, such as radially polarized sources, integrated photonic chips, and quantum communications. However, their low quantum efficiency resulting from forbidden transitions limits their practicality. In this work, we achieve a giant enhancement of up to 34000 for OP exciton emission in indium selenide (InSe) via a designed Ag nanocube-over-Au film plasmonic nanocavity. The large photoluminescence enhancement factor (PLEF) is attributed to the induced OP local electric field (Ez) within the nanocavity, which facilitates effective OP exciton-plasmon interaction and subsequent tremendous enhancement. Moreover, the nanoantenna effect resulting from the effective interaction improves the directivity of spontaneous radiation. Our results not only reveal an effective photoluminescence enhancement approach for OP excitons but also present an avenue for designing on-chip photonic devices with an OP dipole orientation.

16.
Clin Infect Dis ; 76(3): e336-e341, 2023 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-35666466

RESUMO

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs), especially the Delta and Omicron variants, have been reported to show significant resistance to approved neutralizing monoclonal antibodies (mAbs) and vaccines. We previously identified a mAb named 35B5 that harbors broad neutralization to SARS-CoV-2 VOCs. Herein, we explored the protection efficacy of a 35B5-based nasal spray against SARS-CoV-2 VOCs in a small-scale clinical trial. METHODS: We enrolled 30 healthy volunteers who were nasally administered the modified 35B5 formulation. At 12, 24, 48, and 72 hours after nasal spray, the neutralization efficacy of nasal mucosal samples was assayed with pseudoviruses coated with SARS-CoV-2 spike protein of the wild-type strain or the Alpha, Beta, Delta, or Omicron variants. RESULTS: The nasal mucosal samples collected within 24 hours after nasal spray effectively neutralized SARS-CoV-2 VOCs (including Delta and Omicron). Meanwhile, the protection efficacy was 60% effective and 20% effective at 48 and 72 hours after nasal spray, respectively. CONCLUSIONS: A single nasal spray of 35B5 formation conveys 24-hour effective protection against SARS-CoV-2 VOCs, including the Alpha, Beta, Delta, or Omicron variants. Thus, 35B5 nasal spray might be potential in strengthening SARS-CoV-2 prevention, especially in high-risk populations. CLINICAL TRIALS REGISTRATION: 2022-005-02-KY.


Assuntos
COVID-19 , Humanos , Anticorpos Monoclonais/uso terapêutico , Anticorpos Neutralizantes , Anticorpos Antivirais , COVID-19/prevenção & controle , Sprays Nasais , SARS-CoV-2/genética
17.
Talanta ; 253: 123900, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36095940

RESUMO

Research on ion channels and their monoclonal antibodies plays a critical role in drug development and disease diagnosis. The current ion channel researches are often not conducted in the microenvironment for cells survival, which restricts the mechanism study of the links between the cell structure and the ion channel function. In this work, we synthesized gold core-4-mercaptobenzonitrile-sliver shell-goat anti-rabbit immunoglobulin G (Au@4-MBN@Ag@IgG) nanoparticles as surface-enhanced Raman scattering (SERS) nanoprobes for investigating the human ether-a-go-go related gene (hERG) potassium ion channel in cell membranes. This is the first attempt to study ion channels using SERS. Due to the unique core-molecule-shell structure and the silver shell of nanoprobes, strong and stable SERS signal was obtained. With the help of antibodies, the Au@4-MBN@Ag@IgG nanoprobes were captured by hERG antibodies and then bonded with hERG ion channels based on the sandwich immune response. The reporter molecule, 4-MBN, displayed a strong and sharp characteristic peak at 2233 cm-1 in the Raman silent region. The intensity of this peak denoted the concentration of antibodies and the expression of ion channel proteins. We successfully applied this amplification-free method for in-situ imaging the distribution of the hERG ion channel on the transfected HEK293 cell surface at the single-cell level. This hERG ion channel profiling strategy promises a maneuverable tool for ion channel research.


Assuntos
Imunoglobulina G , Canais Iônicos , Humanos , Células HEK293 , Nanopartículas Metálicas
18.
Front Psychiatry ; 14: 1327200, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38274427

RESUMO

Objective: To assess the overall effectiveness of non-pharmacological interventions on internet addiction (IA) in youth. Method: Randomized controlled trials (RCTs) published from their inception to April 1, 2023 were searched in Cochrane, Embase, Medline, Web of Science, China National Knowledge Infrastructure, China Science and Technology Journal Database, Chinese BioMedical Literature Database, and WanFang Data. Two reviewers independently extracted data and evaluated bias using the Cochrane Risk of Bias tool. Results: Sixty-six studies performed from 2007 to 2023, with a total of 4,385 participants, were identified. The NPIs included group counseling, cognitive behavioral therapy, sports intervention, combined interventions, eHealth, educational intervention, positive psychology intervention, sand play intervention, and electrotherapy. The results revealed that NPIs significantly reduced IA levels (standardized mean difference, SMD: -2.01, 95% confidence interval, CI: -2.29 to -1.73, I2 = 93.0%), anxiety levels (SMD: -1.07, 95%CI: -1.41 to -0.73, I2 = 72.4%), depression levels (SMD: -1.11, 95%CI: -1.52 to -0.7, I2 = 84.3%), and SCL-90 (SMD: -0.75, 95%CI: -0.97 to -0.54, I2 = 27.7%). Subgroup analysis stratified by intervention measure showed that cognitive behavioral therapy, group counseling, sports intervention, combined intervention, educational intervention, positive psychology intervention, sandplay intervention, and mobile health were all effective in relieving symptoms of IA except electrotherapy. Conclusion: NPIs appear to be effective in the treatment of IA in youth, which would act as an alternative treatment of IA. Further studies with larger sample sizes and robust designs are needed.

19.
Materials (Basel) ; 15(24)2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36556664

RESUMO

This paper aims to study the penetration effect of harpoons on space debris to ensure the sustainable development of the space environment and solve the increasingly serious space debris problem. Firstly, a harpoon system was designed to capture space debris. Secondly, based on the Johnson-Cook dynamic constitutive model and fracture failure criterion, the finite element models of aluminum alloy plates were established. Then, the ballistic limit theory for the aluminum alloy target predicted the minimum launch velocity of the harpoon. Finally, the validation experiment was set up to verify the correctness of the model. The results show that the error between the simulation results of the speed for the harpoon embedded in the target and the theoretical results of the ballistic limit is 9.1%, which provides guidance for active space debris removal technology.

20.
Appl Opt ; 61(22): 6664-6670, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-36255893

RESUMO

A terahertz surface plasmon resonance (SPR) sensor is designed based on photonic crystal fiber (PCF). Graphene is selectively coated in the cladding hole of the PCF and used as plasmonic material. The coupling mechanism, loss properties, tunability, and refractive index sensing performance of the designed SPR sensor are investigated using the finite element method. The peak of the loss spectrum corresponding to the SPR frequency can be dynamically tuned by adjusting graphene's chemical potential, and a tuning sensitivity of 767.5 GHz/eV is obtained. The SPR frequency red shifts linearly with an increase in the refractive index of analyte from 1.0 to 1.5. An average frequency sensitivity of 208.14 GHz/RIU is obtained. This research provides theoretical guidance for the design of terahertz in-fiber SPR sensors and filters.

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