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1.
PLoS Pathog ; 20(3): e1012130, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38551978

RESUMO

Classical Swine Fever (CSF), caused by the Classical Swine Fever Virus (CSFV), inflicts significant economic losses on the global pig industry. A key factor in the challenge of eradicating this virus is its ability to evade the host's innate immune response, leading to persistent infections. In our study, we elucidate the molecular mechanism through which CSFV exploits m6A modifications to circumvent host immune surveillance, thus facilitating its proliferation. We initially discovered that m6A modifications were elevated both in vivo and in vitro upon CSFV infection, particularly noting an increase in the expression of the methyltransferase METTL14. CSFV non-structural protein 5B was found to hijack HRD1, the E3 ubiquitin ligase for METTL14, preventing METTL14 degradation. MeRIP-seq analysis further revealed that METTL14 specifically targeted and methylated TLRs, notably TLR4. METTL14-mediated regulation of TLR4 degradation, facilitated by YTHDF2, led to the accelerated mRNA decay of TLR4. Consequently, TLR4-mediated NF-κB signaling, a crucial component of the innate immune response, is suppressed by CSFV. Collectively, these data effectively highlight the viral evasion tactics, shedding light on potential antiviral strategies targeting METTL14 to curb CSFV infection.


Assuntos
Adenina , Vírus da Febre Suína Clássica , Peste Suína Clássica , Animais , Vírus da Febre Suína Clássica/genética , Imunidade Inata , Suínos , Receptor 4 Toll-Like
2.
J Virol ; 98(6): e0049424, 2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38757985

RESUMO

Mitochondria are energy producers in cells, which can affect viral replication by regulating the host innate immune signaling pathways, and the changes in their biological functions are inextricably linked the viral life cycle. In this study, we screened a library of 382 mitochondria-targeted compounds and identified the antiviral inhibitors of dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in the de novo synthesis pathway of pyrimidine ribonucleotides, against classical swine fever virus (CSFV). Our data showed that the inhibitors interfered with viral RNA synthesis in a dose-dependent manner, with half-maximal effective concentrations (EC50) ranging from 0.975 to 26.635 nM. Remarkably, DHODH inhibitors obstructed CSFV replication by enhancing the innate immune response including the TBK1-IRF3-STAT1 and NF-κB signaling pathways. Furthermore, the data from a series of compound addition and supplementation trials indicated that DHODH inhibitors also inhibited CSFV replication by blocking the de novo pyrimidine synthesis. Remarkably, DHODH knockdown demonstrated that it was essential for CSFV replication. Mechanistically, confocal microscopy and immunoprecipitation assays showed that the non-structural protein 4A (NS4A) recruited and interacted with DHODH in the perinuclear. Notably, NS4A enhanced the DHODH activity and promoted the generation of UMP for efficient viral replication. Structurally, the amino acids 65-229 of DHODH and the amino acids 25-40 of NS4A were pivotal for this interaction. Taken together, our findings highlight the critical role of DHODH in the CSFV life cycle and offer a potential antiviral target for the development of novel therapeutics against CSF. IMPORTANCE: Classical swine fever remains one of the most economically important viral diseases of domestic pigs and wild boar worldwide. dihydroorotate dehydrogenase (DHODH) inhibitors have been shown to suppress the replication of several viruses in vitro and in vivo, but the effects on Pestivirus remain unknown. In this study, three specific DHODH inhibitors, including DHODH-IN-16, BAY-2402234, and Brequinar were found to strongly suppress classical swine fever virus (CSFV) replication. These inhibitors target the host DHODH, depleting the pyrimidine nucleotide pool to exert their antiviral effects. Intriguingly, we observed that the non-structural protein 4A of CSFV induced DHODH to accumulate around the nucleus in conjunction with mitochondria. Moreover, NS4A exhibited a strong interaction with DHODH, enhancing its activity to promote efficient CSFV replication. In conclusion, our findings enhance the understanding of the pyrimidine synthesis in CSFV infection and expand the novel functions of CSFV NS4A in viral replication, providing a reference for further exploration of antiviral targets against CSFV.


Assuntos
Antivirais , Vírus da Febre Suína Clássica , Di-Hidro-Orotato Desidrogenase , Proteínas não Estruturais Virais , Replicação Viral , Animais , Antivirais/farmacologia , Antivirais/uso terapêutico , Linhagem Celular , Peste Suína Clássica/tratamento farmacológico , Peste Suína Clássica/imunologia , Peste Suína Clássica/metabolismo , Peste Suína Clássica/virologia , Vírus da Febre Suína Clássica/efeitos dos fármacos , Vírus da Febre Suína Clássica/crescimento & desenvolvimento , Vírus da Febre Suína Clássica/imunologia , Vírus da Febre Suína Clássica/metabolismo , Di-Hidro-Orotato Desidrogenase/metabolismo , Relação Dose-Resposta a Droga , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/imunologia , Imunoprecipitação , Microscopia Confocal , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , RNA Viral/biossíntese , Transdução de Sinais/efeitos dos fármacos , Suínos/virologia , Proteínas não Estruturais Virais/metabolismo , Replicação Viral/efeitos dos fármacos
3.
J Virol ; 98(9): e0063524, 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39158346

RESUMO

Flavivirus infection capitalizes on cellular lipid metabolism to remodel the cellular intima, creating a specialized lipid environment conducive to viral replication, assembly, and release. The Japanese encephalitis virus (JEV), a member of the Flavivirus genus, is responsible for significant morbidity and mortality in both humans and animals. Currently, there are no effective antiviral drugs available to combat JEV infection. In this study, we embarked on a quest to identify anti-JEV compounds within a lipid compound library. Our research led to the discovery of two novel compounds, isobavachalcone (IBC) and corosolic acid (CA), which exhibit dose-dependent inhibition of JEV proliferation. Time-of-addition assays indicated that IBC and CA predominantly target the late stage of the viral replication cycle. Mechanistically, JEV nonstructural proteins 1 and 2A (NS1 and NS2A) impede 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) activation by obstructing the liver kinase B1 (LKB1)-AMPK interaction, resulting in decreased p-AMPK expression and a consequent upsurge in lipid synthesis. In contrast, IBC and CA may stimulate AMPK by binding to its active allosteric site, thereby inhibiting lipid synthesis essential for JEV replication and ultimately curtailing viral infection. Most importantly, in vivo experiments demonstrated that IBC and CA protected mice from JEV-induced mortality, significantly reducing viral loads in the brain and mitigating histopathological alterations. Overall, IBC and CA demonstrate significant potential as effective anti-JEV agents by precisely targeting AMPK-associated signaling pathways. These findings open new therapeutic avenues for addressing infections caused by Flaviviruses. IMPORTANCE: This study is the inaugural utilization of a lipid compound library in antiviral drug screening. Two lipid compounds, isobavachalcone (IBC) and corosolic acid (CA), emerged from the screening, exhibiting substantial inhibitory effects on the Japanese encephalitis virus (JEV) proliferation in vitro. In vivo experiments underscored their efficacy, with IBC and CA reducing viral loads in the brain and mitigating JEV-induced histopathological changes, effectively shielding mice from fatal JEV infection. Intriguingly, IBC and CA may activate 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) by binding to its active site, curtailing the synthesis of lipid substances, and thus suppressing JEV proliferation. This indicates AMPK as a potential antiviral target. Remarkably, IBC and CA demonstrated suppression of multiple viruses, including Flaviviruses (JEV and Zika virus), porcine herpesvirus (pseudorabies virus), and coronaviruses (porcine deltacoronavirus and porcine epidemic diarrhea virus), suggesting their potential as broad-spectrum antiviral agents. These findings shed new light on the potential applications of these compounds in antiviral research.


Assuntos
Proteínas Quinases Ativadas por AMP , Antivirais , Vírus da Encefalite Japonesa (Espécie) , Encefalite Japonesa , Metabolismo dos Lipídeos , Replicação Viral , Animais , Metabolismo dos Lipídeos/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , Vírus da Encefalite Japonesa (Espécie)/efeitos dos fármacos , Vírus da Encefalite Japonesa (Espécie)/fisiologia , Camundongos , Antivirais/farmacologia , Humanos , Encefalite Japonesa/tratamento farmacológico , Encefalite Japonesa/virologia , Proteínas Quinases Ativadas por AMP/metabolismo , Chalconas/farmacologia , Triterpenos/farmacologia , Proteínas não Estruturais Virais/metabolismo , Infecções por Flavivirus/tratamento farmacológico , Infecções por Flavivirus/virologia , Infecções por Flavivirus/metabolismo , Flavivirus/efeitos dos fármacos , Linhagem Celular
4.
J Virol ; 97(1): e0192922, 2023 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-36602362

RESUMO

Classical swine fever (CSF), caused by classical swine fever virus (CSFV), is an important and highly infectious pig disease worldwide. Kinesin-1, a molecular motor responsible for transporting cargo along the microtubule, has been demonstrated to be involved in the infections of diverse viruses. However, the role of kinesin-1 in the CSFV life cycle remains unknown. Here, we first found that Kif5B played a positive role in CSFV entry by knockdown or overexpression of Kif5B. Subsequently, we showed that Kif5B was associated with the endosomal and lysosomal trafficking of CSFV in the early stage of CSFV infection, which was reflected by the colocalization of Kif5B and Rab7, Rab11, or Lamp1. Interestingly, trichostatin A (TSA) treatment promoted CSFV proliferation, suggesting that microtubule acetylation facilitated CSFV endocytosis. The results of chemical inhibitors and RNA interference showed that Rac1 and Cdc42 induced microtubule acetylation after CSFV infection. Furthermore, confocal microscopy revealed that cooperation between Kif5B and dynein help CSFV particles move in both directions along microtubules. Collectively, our study shed light on the role of kinesin motor Kif5B in CSFV endocytic trafficking, indicating the dynein/kinesin-mediated bidirectional CSFV movement. The elucidation of this study provides the foundation for developing CSFV antiviral drugs. IMPORTANCE The minus end-directed cytoplasmic dynein and the plus end-directed kinesin-1 are the molecular motors that transport cargo on microtubules in intracellular trafficking, which plays a notable role in the life cycles of diverse viruses. Our previous studies have reported that the CSFV entry host cell is dependent on the microtubule-based motor dynein. However, little is known about the involvement of kinesin-1 in CSFV infection. Here, we revealed the critical role of kinesin-1 that regulated the viral endocytosis along acetylated microtubules induced by Cdc42 and Rac1 after CSFV entry. Mechanistically, once CSFV transported by dynein met an obstacle, it recruited kinesin-1 to move in reverse to the anchor position. This study extends the theoretical basis of intracellular transport of CSFV and provides a potential target for the control and treatment of CSFV infection.


Assuntos
Vírus da Febre Suína Clássica , Peste Suína Clássica , Cinesinas , Animais , Vírus da Febre Suína Clássica/fisiologia , Dineínas/metabolismo , Endocitose , Cinesinas/genética , Cinesinas/metabolismo , Microtúbulos/metabolismo , Microtúbulos/virologia , Suínos , Internalização do Vírus , Replicação Viral/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Transporte Proteico
5.
J Virol ; 97(5): e0036423, 2023 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-37255314

RESUMO

Classical swine fever virus (CSFV) is a highly pathogenic RNA virus belonging to the Flaviviridae family that can cause deadly classical swine fever (CSF) in pigs. However, the molecular details of virus replication in the host are still unclear. Our previous studies have reported that several Rab proteins mediate CSFV entry into host cells, but it is unknown whether CSFV hijacks other Rab proteins for effective viral infection. Here, we systematically studied the role of Rab14 protein in regulating lipid metabolism for promoting viral assembly. First, Rab14 knockdown and overexpression significantly affected CSFV replication, indicating the essential role of Rab14 in CSFV infection. Interestingly, Rab14 could significantly affect virus replication in the late stage of infection. Mechanistically, CSFV NS5A recruited Rab14 to the ER, followed by ceramide transportation to the Golgi apparatus, where sphingomyelin was synthesized. The experimental data of small molecule inhibitors, RNA interference, and replenishment assay showed that the phosphatidylinositol-3-kinase (PI3K)/AKT/AS160 signaling pathway regulated the function of Rab14 to affect the transport of ceramide. More importantly, sphingomyelin on the Golgi apparatus contributed to the assembly of viral particles. Blockage of the Rab14 regulatory pathway induced the reduction of the content of sphingomyelin on the Golgi apparatus, impairing the assembly of virus particles. Our study clarifies that Rab14 regulates lipid metabolism and promotes CSFV replication, which provides insight into a novel function of Rab14 in regulating vesicles to transport lipids to the viral assembly factory. IMPORTANCE The Rab protein family members participate in the viral replication of multiple viruses and play important roles in the virus infection cycle. Our previous research focused on Rab5/7/11, which regulated the trafficking of vesicles in the early stage of CSFV infection, especially in viral endocytosis. However, the role of other Rab proteins in CSFV replication is unclear and needs further clarification. Strikingly, we screened some Rabs and found the important role of Rab14 in CSFV infection. Virus infection mobilized Rab14 to regulate the vesicle to transport ceramide from the ER to the Golgi apparatus, further promoting the synthesis of sphingomyelin and facilitating virus assembly. The treatment of inhibitors showed that the lipid transport mediated by Rab14 was regulated by the PI3K/AKT/AS160 signaling pathway. Knockdown of Rab14 or the treatment with PI3K/AKT/AS160 inhibitors reduced the ceramide content in infected cells and hindered virus assembly. Our study is the first to explain that vesicular lipid transport regulated by Rab promotes CSFV assembly, which is conducive to the development of antiviral drugs.


Assuntos
Ceramidas , Vírus da Febre Suína Clássica , Proteínas Monoméricas de Ligação ao GTP , Montagem de Vírus , Animais , Ceramidas/metabolismo , Peste Suína Clássica , Vírus da Febre Suína Clássica/genética , Vírus da Febre Suína Clássica/fisiologia , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Esfingomielinas/metabolismo , Suínos , Replicação Viral
6.
Chem Biodivers ; 21(4): e202400135, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38425248

RESUMO

Four series of novel pyridine derivatives (17 a-i, 18 a-i, 19 a-e, and 20 a-e) were synthesized and their antimicrobial activities were evaluated. Of all the target compounds, almost half target compounds showed moderate or high antibacterial activity. The 4-F substituted compound 17 d (MIC=0.5 µg/mL) showed the highest antibacterial activity, its activity was twice the positive control compound gatifloxacin (MIC=1.0 µg/mL). For fungus ATCC 9763, the activities of compounds 17 a and 17 d are equivalent to the positive control compound fluconazole (MIC=8 µg/mL). Furthermore, compounds 17 a and 17 d showed little cytotoxicity to human LO2 cells, and did not show hemolysis even at ultra-high concentration (200 µM). The results indicate that these compounds are valuable for further development as antibacterial and antifungal agents.


Assuntos
Tiadiazóis , Humanos , Tiadiazóis/farmacologia , Antifúngicos/farmacologia , Antibacterianos/farmacologia , Fungos , Piridinas/farmacologia , Testes de Sensibilidade Microbiana , Relação Estrutura-Atividade
7.
Molecules ; 28(2)2023 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-36677912

RESUMO

Electrolysis of seawater using solar and wind energy is a promising technology for hydrogen production which is not affected by the shortage of freshwater resources. However, the competition of chlorine evolution reactions and oxygen evolution reactions on the anode is a major obstacle in the upscaling of seawater electrolyzers for hydrogen production and energy storage, which require chlorine-inhibited oxygen evolution electrodes to become commercially viable. In this study, such an electrode was prepared by growing δ-MnO2 nanosheet arrays on the carbon cloth surface. The selectivity of the newly prepared anode towards the oxygen evolution reaction (OER) was 66.3% after 30 min of electrolyzer operation. The insertion of Fe, Co and Ni ions into MnO2 nanosheets resulted in an increased number of trivalent Mn atoms, which had a negative effect on the OER selectivity. Good tolerance of MnO2/CC electrodes to chlorine evolution in seawater electrolysis indicates its suitability for upscaling this important energy conversion and storage technology.

8.
Plant J ; 107(1): 149-165, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33866633

RESUMO

Recent studies have shown that global metabolic reprogramming is a common event in plant innate immunity; however, the relevant molecular mechanisms remain largely unknown. Here, we identified a pathogen-induced glycosyltransferase, UGT73C7, that plays a critical role in Arabidopsis disease resistance through mediating redirection of the phenylpropanoid pathway. Loss of UGT73C7 function resulted in significantly decreased resistance to Pseudomonas syringae pv. tomato DC3000, whereas constitutive overexpression of UGT73C7 led to an enhanced defense response. UGT73C7-activated immunity was demonstrated to be dependent on the upregulated expression of SNC1, a Toll/interleukin 1 receptor-type NLR gene. Furthermore, in vitro and in vivo assays indicated that UGT73C7 could glycosylate p-coumaric acid and ferulic acid, the upstream metabolites in the phenylpropanoid pathway. Mutations that lead to the loss of UGT73C7 enzyme activities resulted in the failure to induce SNC1 expression. Moreover, glycosylation activity of UGT73C7 resulted in the redirection of phenylpropanoid metabolic flux to biosynthesis of hydroxycinnamic acids and coumarins. The disruption of the phenylpropanoid pathway suppressed UGT73C7-promoted SNC1 expression and the immune response. This study not only identified UGT73C7 as an important regulator that adjusts phenylpropanoid metabolism upon pathogen challenge, but also provided a link between phenylpropanoid metabolism and an NLR gene.


Assuntos
Proteínas de Arabidopsis/imunologia , Arabidopsis/fisiologia , Glicosiltransferases/metabolismo , Imunidade Vegetal/fisiologia , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/genética , Ácidos Cumáricos/metabolismo , Resistência à Doença/imunologia , Regulação da Expressão Gênica de Plantas , Glicosilação , Glicosiltransferases/genética , Glicosiltransferases/imunologia , Interações Hospedeiro-Patógeno/fisiologia , Ácidos Isonicotínicos/farmacologia , Doenças das Plantas/imunologia , Plantas Geneticamente Modificadas , Pseudomonas syringae/patogenicidade
9.
Small ; 18(45): e2204474, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36161700

RESUMO

The development of multi-component bi-functional electrocatalysts is necessary for commercialization of high-performance zinc-air batteries. Herein, foamed carbon-supported nickel-iron oxides interspersed with bamboo-like carbon nanotubes are prepared as bi-functional electrocatalysts for this battery type. During high temperature synthesis, edges of carbon sheets comprising the foamed carbon structure become involuted to form short carbon nanotubes. The composite of carbon nanotubes and network carbon confer high specific surface area and high electrical conductivity on the newly prepared materials. The supported NiFe2 O4 phase improves the oxygen reduction reaction (ORR) activity by fixing more N atoms, and high-valent Ni oxide (Ni2 O3 ) promotes the formation of OO bonds, which is conducive to the oxygen evolution reaction (OER). The optimized material exhibits excellent bi-functional electrocatalytic activity toward both ORR and OER, and its use in the assembled zinc-air battery cell results in a high power density of 150 mW cm-2 with long discharge stability.

10.
Chemphyschem ; 23(7): e202100811, 2022 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-34984780

RESUMO

Lithium-sulfur batteries are promising secondary energy storage devices that are mainly limited by its unsatisfactory cyclability owing to inefficient reversible conversion of sulfur and lithium sulfide on the cathode during the discharge/charging process. In this study, nitrogen-doped three-dimensional porous carbon material loaded with CoSe2 nanoparticles (CoSe2 -PNC) is developed as a cathode for lithium-sulfur battery. A combination of CoSe2 and nitrogen-doped porous carbon can efficiently improve the cathode activity and its conductivity, resulting in enhanced redox kinetics of the charge/discharge process. The obtained electrode exhibits a high discharge specific capacity of 1139.6 mAh g-1 at a current density of 0.2 C. After 100 cycles, its capacity remained at 865.7 mAh g-1 thus corresponding to a capacity retention of 75.97 %. In a long-term cycling test, discharge specific capacity of 546.7 mAh g-1 was observed after 300 cycles performed at a current density of 1 C.

11.
Sensors (Basel) ; 22(19)2022 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-36236623

RESUMO

The concept of verifiable delay functions has received attention from researchers since it was first proposed in 2018. The applications of verifiable delay are also widespread in blockchain research, such as: computational timestamping, public random beacons, resource-efficient blockchains, and proofs of data replication. This paper introduces the concept of verifiable delay functions and systematically summarizes the types of verifiable delay functions. Firstly, the description and characteristics of verifiable delay functions are given, and weak verifiable delay functions, incremental verifiable delay functions, decodable verifiable delay functions, and trapdoor verifiable delay functions are introduced respectively. The construction of verifiable delay functions generally relies on two security assumptions: algebraic assumption or structural assumption. Then, the security assumptions of two different verifiable delay functions are described based on cryptography theory. Secondly, a post-quantum verifiable delay function based on super-singular isogeny is introduced. Finally, the paper summarizes the blockchain-related applications of verifiable delay functions.


Assuntos
Blockchain , Segurança Computacional
12.
J Med Virol ; 92(11): 2804-2812, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32542750

RESUMO

A pandemic of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection broke out all over the world; however, epidemiological data and viral shedding in pediatric patients are limited. We conducted a retrospective, multicenter study, and followed-up with all children from the families with SARS-CoV-2 infected members in Zhejiang Province, China. All infections were confirmed by testing the SARS-CoV-2 RNA with real-time reverse transcription PCR method, and epidemiological data between children and adults in the same families were compared. Effect of antiviral therapy was evaluated observationally and fecal-viral excretion times among groups with different antiviral regiments were compared with Kaplan-Meier plot. By 29 February 2020, 1298 cases from 883 families were confirmed with SARS-CoV-2 infection and 314 of which were families with children. Incidence of infection in child close contacts was significantly lower than that in adult contacts (13.2% vs 21.2%). The mean age of 43 pediatric cases was 8.2 years and mean incubation period was 9.1 days. Forty (93.0%) were family clustering. Thirty-three children had coronavirus disease 2019 (20 pneumonia) with mild symptoms and 10 were asymptomatic. Fecal SARS-CoV-2 RNA detection was positive in 91.4% (32/35) cases and some children had viral excretion time over 70 days. Viral clearance time was not different among the groups treated with different antiviral regiments. No subsequent infection was observed in family contacts of fecal-viral-excreting children. Children have lower susceptibility of SARS-CoV-2 infection, longer incubation, and fecal-viral excretion time. Positive results of fecal SARS-CoV-2 RNA detection were not used as indication for hospitalization or quarantine.


Assuntos
COVID-19/epidemiologia , Fezes/virologia , SARS-CoV-2/fisiologia , Eliminação de Partículas Virais , Adolescente , Antivirais/uso terapêutico , COVID-19/transmissão , Portador Sadio/epidemiologia , Portador Sadio/virologia , Criança , Pré-Escolar , China/epidemiologia , Família , Feminino , Hospitalização , Humanos , Incidência , Lactente , Masculino , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2/patogenicidade
13.
Chemistry ; 26(47): 10752-10758, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32101342

RESUMO

Cost efficient bifunctional air cathodes possessing high electrocatalytic activity are of great importance for the development of secondary Zn-air batteries. In this work, cobalt nanoparticles are encapsulated within a 3D N-doped open network of carbon tubes (Co@N-CNTs) by a molten-salt synthesis procedure conducted at a high temperature. Physical characterization demonstrates that Co@N-CNTs are comprised of Co particle inserted carbon tubes with mesoporous tube walls, providing significant active surface area for electrochemical reactions. High electrocatalytic activity of Co@N-CNTs towards both oxygen evolution and oxygen reduction reactions is due to its well-developed active surface and a synergistic effect between N-doped carbon and Co nanoparticles. Both primary and secondary Zn-air battery cells assembled using Co@N-CNTs as an air cathode show higher electrochemical performance than similar cells containing commercial Pt/C and Pt/C +RuO2 , making the newly developed material a promising alternative to existing metal-based air cathodes.

14.
Chemistry ; 26(52): 12067-12074, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32597520

RESUMO

To obtain a highly active, stable, and binder-free electrode based on transition-metal compounds for water splitting, nickel foam-supported 3D NiMoO4 nanosheet arrays modified with 0D Fe-doped carbon quantum dots (Fe-CQDs/NiMoO4 /NF) are synthesized. The structure characterizations indicated that 0D Fe-CQDs are evenly dispersed onto the NiMoO4 sheets of the arrays. The contact angle analysis confirmed that the surface hydrophilia of the arrays is improved after the 0D Fe-CQDs are deposited 3D on the NiMoO4 sheets. Here, both the activity and durability in electrochemical water splitting are significantly enhanced with the Fe-CQDs/NiMoO4 /NF catalysts. At a current density of 10 mA cm-2 , the resultant Fe-CQDs/NiMoO4 /NF revealed an overpotential of only 117 mV for the hydrogen evolution reaction (HER), a relatively low overpotential of 336 mV toward the oxygen evolution reaction (OER), and a Faraday efficiency of up to 99 %. This performance can be attributed to the unique 3D nanosheet array structure, the synergistic effect, and the optimal hydrophilia for gas evolution evolved from the electrode surface.

15.
Nanotechnology ; 31(42): 425404, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32604073

RESUMO

Hollow structured nanomaterials with void space available inside the shells can effectively enhance electrocatalytic activity due to their high specific surface area, volume buffer and shell permeability properties. In this study, low-cost and hollow structured bimetal phosphide nanowires are synthesized directly on Ni foam via the Kirkendall effect by using NaH2PO2 as a phosphorizing agent at 350 °C. Both the crystal and hollow structures of the obtained phosphide can be efficiently tuned by controlling the amount of phosphorizing agent and the phosphorizing time. The morphology and microstructure of the obtained phosphides are characterised using various techniques, which indicate that the formation mechanism of the hollow structure is consistent with the Kirkendall effect. The optimized bimetal phosphide sample demonstrates a low onset potential (59 mV) at a current density of 10 mA cm-2, low charge transfer resistance (0.83 Ω) and superior durability in the hydrogen evolution reaction (HER) for water electrolysis. The electrochemical results clearly demonstrate that the hollow structure can efficiently improve the HER properties and the obtained phosphide is a promising HER catalysts for water splitting in KOH or seawater electrolytes.

16.
Small ; 15(29): e1802861, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30474305

RESUMO

Porous Ni(OH)2 nanoflakes are directly grown on the surface of nickel foam supported Ni3 Se2 nanowire arrays using an in situ growth procedure to form 3D Ni3 Se2 @Ni(OH)2 hybrid material. Owing to good conductivity of Ni3 Se2 , high specific capacitance of Ni(OH)2 and its unique architecture, the obtained Ni3 Se2 @Ni(OH)2 exhibits a high specific capacitance of 1689 µAh cm-2 (281.5 mAh g-1 ) at a discharge current of 3 mA cm-2 and a superior rate capability. Both the high energy density of 59.47 Wh kg-1 at a power density of 100.54 W kg-1 and remarkable cycling stability with only a 16.4% capacity loss after 10 000 cycles are demonstrated in an asymmetric supercapacitor cell comprising Ni3 Se2 @Ni(OH)2 as a positive electrode and activated carbon as a negative electrode. Furthermore, the cell achieved a high energy density of 50.9 Wh L-1 at a power density of 83.62 W L-1 in combination with an extraordinary coulombic efficiency of 97% and an energy efficiency of 88.36% at 5 mA cm-2 when activated carbon is replaced by metal hydride from a commercial NiMH battery. Excellent electrochemical performance indicates that Ni3 Se2 @Ni(OH)2 composite can become a promising electrode material for energy storage applications.

17.
Chemistry ; 25(11): 2868-2876, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30548500

RESUMO

The development of alternative electrocatalysts exhibiting high activity in the oxygen reduction reaction (ORR) is vital for the deployment of large-scale clean energy devices, such as fuel cells and zinc-air batteries. N-doped carbon materials offer a promising platform for the design and synthesis of electrocatalysts due to their high ORR activity, high surface area, and tunable porosity. In this study, materials in which MnO nanoparticles are entrapped in N-doped mesoporous carbon (MnO/NC) were developed as electrocatalysts for the ORR, and their performances were evaluated in zinc-air batteries. The obtained carbon materials had large surface area and high electrocatalytic activity toward the ORR. The carbon compounds were fabricated by using NaCl as template in a one-pot process, which significantly simplifies the procedure for preparing mesoporous carbon materials and in turn reduces the total cost. A primary zinc-air battery based on this material exhibits an open-circuit voltage of 1.49 V, which is higher than that of conventional zinc-air batteries with Pt/C (Pt/C cell) as ORR catalyst (1.41 V). The assembled zinc-air battery delivered a peak power density of 168 mW cm-2 at a current density of about 200 mA cm-2 , which is higher than that of an equivalent Pt/C cell (151 mW cm-2 at a current density of ca. 200 mA cm-2 ). The electrocatalytic data revealed that MnO/NC is a promising nonprecious-metal ORR catalyst for practical applications in metal-air batteries.

18.
Analyst ; 144(16): 4925-4934, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31313759

RESUMO

Designing highly active electrode is important for the fabrication of electrochemical sensing platforms, and core-shell nanostructures with large specific surface areas and ease of accessibility are effective probes for the detection of biomolecules. In this work, we report the development of hierarchical core-shell Ni3S2/NiMoO4 nanowires on a nickel foam substrate (Ni-Ni3S2/NiMoO4) as a non-noble metal catalyst electrode for the electrochemical oxidation of glucose in alkaline electrolyte. As an electrochemical sensor for glucose detection, the fabricated hierarchical Ni-Ni3S2/NiMoO4 core-shell nanowires display an enhanced catalytic response, a fast response time of 1 s with a limit of detection (LOD) of 0.055 µM (S/N = 3), and a higher sensitivity of 10.49 µA µM-1 cm-2. Unlike Ni3S2 or NiMoO4 electrodes, the observed superior catalytic activity towards glucose is mainly due to the promotional effect of NiMoO4 nanosheets on the Ni3S2 nanowires, which can increase the large active surface area and generate numerous active sites within and on the surface walls of the nanowire structures. The developed Ni-Ni3S2/NiMoO4 nanowire electrode can selectively detect glucose in the presence of other carbohydrates, such as fructose, sucrose, lactose, maltose, galactose, mannose, and xylose, indicating potential anti-interference properties. The Ni-Ni3S2/NiMoO4 nanowire electrode is highly stable for reuse and its practical application is demonstrated using real blood serum samples. These results demonstrate that hierarchical core-shell Ni3S2/NiMoO4 nanowires show potential for application in the development of low-cost applied glucose sensors.


Assuntos
Glicemia/análise , Nanofios/química , Níquel/química , Glicemia/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Humanos , Limite de Detecção , Molibdênio/química , Oxirredução
19.
J Asthma ; 56(4): 341-349, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-29621415

RESUMO

OBJECTIVE: Airway remodeling is an important pathological feature of asthma. Excessive deposition of extracellular matrix (e.g., collagen) secreted from fibroblasts is a major factor contributing to airway remodeling. Currently, the mechanism by which collagen continues to be oversynthesized in the airway remains unclear. In this study, we investigated the role of the microRNA-21 (miR-21) and TGFß/Smad signaling pathway in human bronchial fibroblasts (HBFs), and explored the regulatory mechanism of airway remodeling. METHODS: HBFs were cultured in vitro and treated with the transforming growth factor ß (TGFß), receptor inhibitor (SB431542), and TGFß1. miR-21 and Smad7 overexpressing lentiviruses, as well as an miR-21 interfering lentivirus were constructed and transfected into HBFs. Western blotting was used to determine the expression of airway remodeling-related proteins and proteins in the TGFß/Smad signaling pathway. miR-21 expression was measured by quantitative real-time PCR. RESULTS: The high expression of miR-21 induced by TGFß1 was reduced following the treatment with the SB431542 in HBFs. Smad7 overexpression inhibited the elevated expression of the COL I protein induced by miR-21 overexpression in HBFs. Inhibiting miR-21 expression upregulated the level of Smad7 protein, thus reducing the expression of airway remodeling-related proteins induced by TGFß1 stimulation in HBFs. CONCLUSIONS: TGFß1 can induce miR-21 expression in HBFs through the TGFß/Smad signaling pathway to promote airway remodeling. miR-21 downregulates Smad7, activates the TGFß/Smad signaling pathway, and promotes airway remodeling. Mutual regulation between miR-21 and the TGFß/Smad signaling pathway in HBFs promotes airway remodeling.


Assuntos
Remodelação das Vias Aéreas/genética , Asma/genética , MicroRNAs/genética , Proteína Smad7/genética , Fator de Crescimento Transformador beta/genética , Análise de Variância , Asma/patologia , Western Blotting , Células Cultivadas , Estudos de Coortes , Feminino , Fibroblastos/patologia , Regulação da Expressão Gênica , Humanos , Masculino , Reação em Cadeia da Polimerase em Tempo Real/métodos , Valores de Referência , Transdução de Sinais/genética
20.
Sensors (Basel) ; 19(7)2019 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-30986985

RESUMO

Robots frequently need to work in human environments and handle many different types of objects. There are two problems that make this challenging for robots: human environments are typically cluttered, and the multi-finger robot hand needs to grasp and to lift objects without knowing their mass and damping properties. Therefore, this study combined vision and robot hand real-time grasp control action to achieve reliable and accurate object grasping in a cluttered scene. An efficient online algorithm for collision-free grasping pose generation according to a bounding box is proposed, and the grasp pose will be further checked for grasp quality. Finally, by fusing all available sensor data appropriately, an intelligent real-time grasp system was achieved that is reliable enough to handle various objects with unknown weights, friction, and stiffness. The robots used in this paper are the NTU 21-DOF five-finger robot hand and the NTU 6-DOF robot arm, which are both constructed by our Lab.

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