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1.
Nat Mater ; 23(6): 741-746, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38740956

RESUMO

Confining materials to two-dimensional forms changes the behaviour of the electrons and enables the creation of new devices. However, most materials are challenging to produce as uniform, thin crystals. Here we present a synthesis approach where thin crystals are grown in a nanoscale mould defined by atomically flat van der Waals (vdW) materials. By heating and compressing bismuth in a vdW mould made of hexagonal boron nitride, we grow ultraflat bismuth crystals less than 10 nm thick. Due to quantum confinement, the bismuth bulk states are gapped, isolating intrinsic Rashba surface states for transport studies. The vdW-moulded bismuth shows exceptional electronic transport, enabling the observation of Shubnikov-de Haas quantum oscillations originating from the (111) surface state Landau levels. By measuring the gate-dependent magnetoresistance, we observe multi-carrier quantum oscillations and Landau level splitting, with features originating from both the top and bottom surfaces. Our vdW mould growth technique establishes a platform for electronic studies and control of bismuth's Rashba surface states and topological boundary modes1-3. Beyond bismuth, the vdW-moulding approach provides a low-cost way to synthesize ultrathin crystals and directly integrate them into a vdW heterostructure.

2.
N Engl J Med ; 385(20): 1845-1855, 2021 11 11.
Artigo em Inglês | MEDLINE | ID: mdl-34758252

RESUMO

BACKGROUND: In patients with symptomatic heart failure, sacubitril-valsartan has been found to reduce the risk of hospitalization and death from cardiovascular causes more effectively than an angiotensin-converting-enzyme inhibitor. Trials comparing the effects of these drugs in patients with acute myocardial infarction have been lacking. METHODS: We randomly assigned patients with myocardial infarction complicated by a reduced left ventricular ejection fraction, pulmonary congestion, or both to receive either sacubitril-valsartan (97 mg of sacubitril and 103 mg of valsartan twice daily) or ramipril (5 mg twice daily) in addition to recommended therapy. The primary outcome was death from cardiovascular causes or incident heart failure (outpatient symptomatic heart failure or heart failure leading to hospitalization), whichever occurred first. RESULTS: A total of 5661 patients underwent randomization; 2830 were assigned to receive sacubitril-valsartan and 2831 to receive ramipril. Over a median of 22 months, a primary-outcome event occurred in 338 patients (11.9%) in the sacubitril-valsartan group and in 373 patients (13.2%) in the ramipril group (hazard ratio, 0.90; 95% confidence interval [CI], 0.78 to 1.04; P = 0.17). Death from cardiovascular causes or hospitalization for heart failure occurred in 308 patients (10.9%) in the sacubitril-valsartan group and in 335 patients (11.8%) in the ramipril group (hazard ratio, 0.91; 95% CI, 0.78 to 1.07); death from cardiovascular causes in 168 (5.9%) and 191 (6.7%), respectively (hazard ratio, 0.87; 95% CI, 0.71 to 1.08); and death from any cause in 213 (7.5%) and 242 (8.5%), respectively (hazard ratio, 0.88; 95% CI, 0.73 to 1.05). Treatment was discontinued because of an adverse event in 357 patients (12.6%) in the sacubitril-valsartan group and 379 patients (13.4%) in the ramipril group. CONCLUSIONS: Sacubitril-valsartan was not associated with a significantly lower incidence of death from cardiovascular causes or incident heart failure than ramipril among patients with acute myocardial infarction. (Funded by Novartis; PARADISE-MI ClinicalTrials.gov number, NCT02924727.).


Assuntos
Aminobutiratos/uso terapêutico , Antagonistas de Receptores de Angiotensina/uso terapêutico , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Compostos de Bifenilo/uso terapêutico , Insuficiência Cardíaca/prevenção & controle , Infarto do Miocárdio/tratamento farmacológico , Ramipril/uso terapêutico , Valsartana/uso terapêutico , Idoso , Aminobutiratos/efeitos adversos , Antagonistas de Receptores de Angiotensina/efeitos adversos , Inibidores da Enzima Conversora de Angiotensina/efeitos adversos , Compostos de Bifenilo/efeitos adversos , Doenças Cardiovasculares/mortalidade , Método Duplo-Cego , Combinação de Medicamentos , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Hipotensão/induzido quimicamente , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/complicações , Infarto do Miocárdio/mortalidade , Modelos de Riscos Proporcionais , Ramipril/efeitos adversos , Volume Sistólico , Valsartana/efeitos adversos , Disfunção Ventricular Esquerda/etiologia
3.
Circulation ; 146(14): 1067-1081, 2022 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-36082663

RESUMO

BACKGROUND: Angiotensin-converting enzyme inhibitors attenuate left ventricular (LV) enlargement after acute myocardial infarction (AMI). Preclinical data suggest similar benefits with combined angiotensin receptor neprilysin inhibition, but human data are conflicting. The PARADISE-MI Echo Study (Prospective ARNI Versus ACE Inhibitor Trial to Determine Superiority in Reducing Heart Failure Events After Myocardial Infarction) tested the effect of sacubitril/valsartan compared with ramipril on LV function and adverse remodeling after high risk-AMI. METHODS: In a prespecified substudy, 544 PARADISE-MI participants were enrolled in the Echo Study to undergo protocol echocardiography at randomization and after 8 months. Patients were randomized within 0.5 to 7 days of presentation with their index AMI to receive a target dose of sacubitril/valsartan 200 mg or ramipril 5 mg twice daily. Echocardiographic measures were performed at a core laboratory by investigators blinded to treatment assignment. The effect of treatment on change in echo measures was assessed with ANCOVA with adjustment for baseline value and enrollment region. The primary end points were change in LV ejection fraction (LVEF) and left atrial volume (LAV), and prespecified secondary end points included changes in LV end-diastolic and end-systolic volumes. RESULTS: Mean age was 64±12 years; 26% were women; mean LVEF was 42±12%; and LAV was 49±17 mL. Of 544 enrolled patients, 457 (84%) had a follow-up echo at 8 months (228 taking sacubitril/valsartan, 229 taking ramipril). There was no significant difference in change in LVEF (P=0.79) or LAV (P =0.62) by treatment group. Patients randomized to sacubitril/valsartan demonstrated less increase in LV end-diastolic volume (P=0.025) and greater decline in LV mass index (P=0.037), increase in tissue Doppler e'lat (P=0.005), decrease in E/e'lat (P=0.045), and decrease in tricuspid regurgitation peak velocity (P=0.024) than patients randomized to ramipril. These differences remained significant after adjustment for differences in baseline characteristics. Baseline LVEF, LV end-diastolic volume, LV end-systolic volume, LV mass index, LAV, and Doppler-based diastolic indices were associated with risk of cardiovascular death or incident heart failure. CONCLUSIONS: Treatment with sacubitril/valsartan compared with ramipril after AMI did not result in changes in LVEF or LAV at 8 months. Patients randomized to sacubitril/valsartan had less LV enlargement and greater improvement in filling pressure. Measures of LV size, systolic function, and diastolic properties were predictive of cardiovascular death and incident heart failure after AMI in this contemporary, well-treated cohort. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02924727.


Assuntos
Insuficiência Cardíaca , Infarto do Miocárdio , Idoso , Aminobutiratos/efeitos adversos , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Compostos de Bifenilo/uso terapêutico , Combinação de Medicamentos , Ecocardiografia , Feminino , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/diagnóstico por imagem , Insuficiência Cardíaca/tratamento farmacológico , Humanos , Hipertrofia Ventricular Esquerda/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/tratamento farmacológico , Neprilisina , Estudos Prospectivos , Ramipril/farmacologia , Ramipril/uso terapêutico , Receptores de Angiotensina/uso terapêutico , Volume Sistólico/fisiologia , Tetrazóis/efeitos adversos , Valsartana/uso terapêutico
4.
Circulation ; 146(23): 1749-1757, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36321459

RESUMO

BACKGROUND: In patients who survive an acute myocardial infarction (AMI), angiotensin-converting enzyme inhibitors decrease the risk of subsequent major cardiovascular events. Whether angiotensin-receptor blockade and neprilysin inhibition with sacubitril/valsartan reduce major coronary events more effectively than angiotensin-converting enzyme inhibitors in high-risk patients with recent AMI remains unknown. We aimed to compare the effects of sacubitril/valsartan on coronary outcomes in patients with AMI. METHODS: We conducted a prespecified analysis of the PARADISE-MI trial (Prospective ARNI vs ACE Inhibitors Trial to Determine Superiority in Reducing Heart Failure Events After MI), which compared sacubitril/valsartan (97/103 mg twice daily) with ramipril (5 mg twice daily) for reducing heart failure events after myocardial infarction in 5661 patients with AMI complicated by left ventricular systolic dysfunction, pulmonary congestion, or both. In the present analysis, the prespecified composite coronary outcome was the first occurrence of death from coronary heart disease, nonfatal myocardial infarction, hospitalization for angina, or postrandomization coronary revascularization. RESULTS: Patients were randomly assigned at a median of 4.4 [3.0-5.8] days after index AMI (ST-segment-elevation myocardial infarction 76%, non-ST-segment-elevation myocardial infarction 24%), by which time 89% of patients had undergone coronary reperfusion. Compared with ramipril, sacubitril/valsartan decreased the risk of coronary outcomes (hazard ratio, 0.86 [95% CI, 0.74-0.99], P=0.04) over a median follow-up of 22 months. Rates of the components of the composite outcomes were lower in patients on sacubitril/valsartan but were not individually significantly different. CONCLUSIONS: In survivors of an AMI with left ventricular systolic dysfunction and pulmonary congestion, sacubitril/valsartan-compared with ramipril-reduced the risk of a prespecified major coronary composite outcome. Dedicated studies are necessary to confirm this finding and elucidate its mechanism. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02924727.


Assuntos
Insuficiência Cardíaca , Infarto do Miocárdio , Disfunção Ventricular Esquerda , Humanos , Aminobutiratos/uso terapêutico , Antagonistas de Receptores de Angiotensina/uso terapêutico , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Angiotensinas , Compostos de Bifenilo , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/tratamento farmacológico , Infarto do Miocárdio/tratamento farmacológico , Neprilisina/antagonistas & inibidores , Estudos Prospectivos , Ramipril/uso terapêutico , Receptores de Angiotensina , Volume Sistólico , Tetrazóis/uso terapêutico , Valsartana/uso terapêutico , Disfunção Ventricular Esquerda/complicações
5.
Phys Rev Lett ; 130(3): 036203, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36763396

RESUMO

Flat bands (FBs), presenting a strongly interacting quantum system, have drawn increasing interest recently. However, experimental growth and synthesis of FB materials have been challenging and have remained elusive for the ideal form of monolayer materials where the FB arises from destructive quantum interference as predicted in 2D lattice models. Here, we report surface growth of a self-assembled monolayer of 2D hydrogen-bond (H-bond) organic frameworks (HOFs) of 1,3,5-tris(4-hydroxyphenyl)benzene (THPB) on Au(111) substrate and the observation of FB. High-resolution scanning tunneling microscopy or spectroscopy shows mesoscale, highly ordered, and uniform THPB HOF domains, while angle-resolved photoemission spectroscopy highlights a FB over the whole Brillouin zone. Density-functional-theory calculations and analyses reveal that the observed topological FB arises from a hidden electronic breathing-kagome lattice without atomically breathing bonds. Our findings demonstrate that self-assembly of HOFs provides a viable approach for synthesis of 2D organic topological materials, paving the way to explore many-body quantum states of topological FBs.

6.
Nanotechnology ; 33(41)2022 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-35724633

RESUMO

Quantum anomalous Hall effect (QAHE) and quantum spin Hall effect (QSHE) are two interesting physical manifestations of 2D materials that have an intrinsic nontrivial band topology. In principle, they are ground-state equilibrium properties characterized by Fermi level lying in a topological gap, below which all the occupied bands are summed to a non-zero topological invariant. Here, we propose theoretical concepts and models of 'excited' QAHE (EQAHE) and EQSHE generated by dissociation of an excitonic insulator (EI) state with complete population inversion (CPI), a uniquemany-bodyground state enabled by two yin-yang flat bands (FBs) of opposite chirality hosted in a diatomic Kagome lattice. The two FBs have a trivial gap in between, i.e. the system is a trivial insulator in thesingle-particleground-state, but nontrivial gaps above and below, so that upon photoexcitation the quasi-Fermi levels of both electrons and holes will lie in a nontrivial gap achieved by the CPI-EI state, as demonstrated by exact diagonalization calculations. Then dissociation of singlet and triplet EI state will lead to EQAHE and EQSHE, respectively. Realizations of yin-yang FBs in real materials are also discussed.

7.
Environ Res ; 211: 113057, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35271837

RESUMO

Electrochemical oxidation is an effective technique for treating persistent organic pollutants, which are hardly removed in conventional wastewater treatment plants. Sulfate and chloride salts commonly used and present in natural wastewater influence the electrochemical degradation process. In this study, the effect of electrolyte composition on the active sulfate species (SO4●⁻ and S2O82⁻) formation, benzotriazole degradation-a model organic compound, and chlorinated by-products distribution have been investigated while using a boron-doped diamond (BDD) anode. Different Na2SO4:NaNO3 and Na2SO4:NaCl ratios with constant conductivity of 10 mS/cm were used in the experiments and applied anode potential was kept constant at 4.3 V vs. Ag/AgCl. The electrogenerated SO4●⁻ and S2O82⁻ formation were faster in 10:1 and 2:1 Na2SO4:NaNO3 ratios than in the 1:0 ratio. The ●OH-mediated SO4●⁻ production has prevailed in 10:1 and 2:1 ratios. However, ●OH-mediated SO4●⁻ production has hindered the 1:0 ratio due to excess chemisorption of SO42⁻ on the BDD anode. Similarly, the faster benzotriazole degradation, mineralization, and lowest energy consumption were achieved in the 10:1 Na2SO4:NaNO3 and Na2SO4:NaCl ratio. Besides, chlorinated organic by-product concentration (AOX) was lower in the 10:1 Na2SO4:NaCl ratio but increased with the increasing chloride ratio in the electrolyte. LC-MS analysis shows that several chlorinated organic transformation products were produced in 0:1 to 2:1 ratio, which was not found in the 10:1 Na2SO4:NaCl ratio. A comparatively higher amount of ClO4⁻ was formed in the 10:1 ratio than in 2:1 to 0:1 ratio. This ClO4⁻ formation train evidence the effective ●OH generation in a sulfate-enriched condition because the ClO4⁻ formation is positively correlated to ●OH concentration. Overall results show that sulfate-enriched electrolyte compositions are beneficial for electrochemical oxidation of biorecalcitrant organic pollutants.


Assuntos
Sulfatos , Poluentes Químicos da Água , Boro , Cloretos , Diamante , Eletrólitos/química , Oxirredução , Cloreto de Sódio , Sulfatos/química , Triazóis , Poluentes Químicos da Água/química
8.
Nano Lett ; 21(1): 230-235, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33263394

RESUMO

Using first-principles calculations, we investigate the electronic and topological properties of an antiferromagnetic (AFM) superatomic graphene lattice superimposed on a bipartite honeycomb lattice governed by Lieb's theorem of itinerant magnetism. It affords a concrete material realization of the AFM honeycomb model with a Dirac Mott insulating state, characterized by a gap opening at the Dirac point due to inversion symmetry breaking by long-range AFM order. The opposite Berry curvatures of the K and K' valleys induces a circular dichroism (CD) Hall effect. Different from the valley Hall effect that activates only one valley, the CD Hall effect activates carriers from both K and K' valleys, generating the opposite directions of transversal Hall currents for the left- and right-handed circularly polarized light, respectively.

9.
Phys Rev Lett ; 126(19): 196403, 2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34047585

RESUMO

The excitonic insulator (EI) state is a strongly correlated many-body ground state, arising from an instability in the band structure toward exciton formation. We show that the flat valence and conduction bands of a semiconducting diatomic Kagome lattice, as exemplified in a superatomic graphene lattice, can possibly conspire to enable an interesting triplet EI state, based on density-functional theory calculations combined with many-body GW and Bethe-Salpeter equation. Our results indicate that massive carriers in flat bands with highly localized electron and hole wave functions significantly reduce the screening and enhance the exchange interaction, leading to an unusually large triplet exciton binding energy (∼1.1 eV) exceeding the GW band gap by ∼0.2 eV and a large singlet-triplet splitting of ∼0.4 eV. Our findings enrich once again the intriguing physics of flat bands and extend the scope of EI materials.

10.
Phys Rev Lett ; 126(17): 176102, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33988396

RESUMO

Deposition of Bi on InSb(111)B reveals a striking Sierpinski-triangle (ST)-like structure in Bi thin films. Such a fractal geometric topology is further shown to turn off the intrinsic electronic topology in a thin film. Relaxation of a huge misfit strain of about 30% to 40% between Bi adlayer and substrate is revealed to drive the ST-like island formation. A Frenkel-Kontrova model is developed to illustrate the enhanced strain relief in the ST islands offsetting the additional step energy cost. Besides a sufficiently large tensile strain, forming ST-like structures also requires larger adlayer-substrate and intra-adlayer elastic stiffnesses, and weaker intra-adlayer interatomic interactions.

11.
Phys Chem Chem Phys ; 22(44): 25827-25832, 2020 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-33150895

RESUMO

π-Orbital bonding plays an important role not only in traditional molecular science and solid-state chemistry but also in modern quantum physics and materials, such as the relativistic Dirac states formed by bonding and antibonding π-bands in graphene. Here, we disclose an interesting manifestation of π-orbitals in forming the Yin-Yang Kagome bands, which host potentially a range of exotic quantum phenomena. Based on first-principles calculations and tight-binding orbital analyses, we show that the frontier π2- and π3-orbitals in anilato-based metal-organic frameworks form concurrently a conduction and valence set of Kagome bands, respectively, but with opposite signs of lattice hopping to constitute a pair of enantiomorphic Yin and Yang Kagome bands, as recently proposed in a diatomic Kagome lattice. The twisted configuration of neighboring benzene-derived organic ligands bridged by an octahedrally O-coordinated metal ion is found to play a critical role in creating the opposite sign of lattice hopping for the π2- versus π3-orbitals. Our finding affords a new material platform to study π-orbital originated quantum chemistry and physics.

12.
Zhongguo Zhong Yao Za Zhi ; 44(7): 1464-1474, 2019 Apr.
Artigo em Zh | MEDLINE | ID: mdl-31090306

RESUMO

To predict the targets of active ingredients of Kuihua Hugan Tablets by network pharmacology, and explore the "multi-component-multi-target-multi-pathway" hepatoprotective mechanism of action. First, through traditional Chinese medicine systems pharmacology(TCMSP) and TCM Database@Taiwan Database, main active ingredients of Kuihua Hugan Tablets were screened out based on oral bioavailability(OB), drug-likeness(DL) and effective half-lives(HL). The targets of active ingredients of Kuihua Hugan Tablets were predicted based on the PharmMapper method. Then, the prediction was conducted by screening the target genes associated with chronic hepatitis and early cirrhosis through CooLGeN and GeneCards databases. Target gene functions and signal pathways were analyzed by bioinformatics annotation database Metascape. Cytoscape software was used to construct the Kuihua Hugan Tablets ingredient-target and ingredient-target-pathway network. String database combined with Cytoscape software was used to construct the networks of component-target and component-target-pathway. STRING database was combined with Cytoscape software to draw protein-protein interaction(PPI) network and conduct network topology analysis. Finally, Systems Dock Web Site software was applied in verifying the molecular docking between active ingredients and potential protein targets. A total of 26 compounds and 509 potential targets were screened out from Kuihua Hugan Tablets in the experiment. The results of PPI network analysis indicated that albumin(ALB), insulin-like growth factor 1(IGF1), matrix metalloproteinase-9(MMP9), matrix metalloproteinase-2(MMP2), non-receptor tyrosine kinase proto-oncogene(SRC), estrogen receptor 1(ESR1) and cancer-signal transduction-inflammation-drugs metabolism-related biological processes and metabolic pathways were closely associated with the active ingredients in Kuihua Hugan Tablets. The effects of Kuihua Hugan Tablets in alleviating chronic hepatitis and early cirrhosis indicated the multi-component, multi-target, and multi-pathway characteristics of traditional Chinese medicines, providing new ideas for further research and development of Kuihua Hugan Tablets.


Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Redes e Vias Metabólicas , Mapeamento de Interação de Proteínas , Medicina Tradicional Chinesa , Simulação de Acoplamento Molecular , Comprimidos
14.
Phys Rev Lett ; 121(6): 066401, 2018 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-30141639

RESUMO

We theoretically demonstrate that screw dislocation (SD), a 1D topological defect widely present in semiconductors, exhibits ubiquitously a new form of spin-orbit coupling (SOC) effect. Differing from the widely known conventional 2D Rashba-Dresselhaus (RD) SOC effect that typically exists at surfaces or interfaces, the deep-level nature of SD-SOC states in semiconductors readily makes it an ideal SOC. Remarkably, the spin texture of 1D SD-SOC, pertaining to the inherent symmetry of SD, exhibits a significantly higher degree of spin coherency than the 2D RD-SOC. Moreover, the 1D SD-SOC can be tuned by ionicity in compound semiconductors to ideally suppress spin relaxation, as demonstrated by comparative first-principles calculations of SDs in Si/Ge, GaAs, and SiC. Our findings therefore open a new door to manipulating spin transport in semiconductors by taking advantage of an otherwise detrimental topological defect.

16.
Nano Lett ; 17(10): 6166-6170, 2017 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-28898086

RESUMO

Superconductivity is a fascinating quantum phenomenon characterized by zero electrical resistance and the Meissner effect. To date, several distinct families of superconductors (SCs) have been discovered. These include three-dimensional (3D) bulk SCs in both inorganic and organic materials as well as two-dimensional (2D) thin film SCs but only in inorganic materials. Here we predict superconductivity in 2D and 3D organic metal-organic frameworks by using first-principles calculations. We show that the highly conductive and recently synthesized Cu-benzenehexathial (BHT) is a Bardeen-Cooper-Schrieffer SC. Remarkably, the monolayer Cu-BHT has a critical temperature (Tc) of 4.43 K, while Tc of bulk Cu-BHT is 1.58 K. Different from the enhanced Tc in 2D inorganic SCs which is induced by interfacial effects, the Tc enhancement in this 2D organic SC is revealed to be the out-of-plane soft-mode vibrations, analogous to surface mode enhancement originally proposed by Ginzburg. Our findings not only shed new light on better understanding 2D superconductivity but also open a new direction to search for SCs by interface engineering with organic materials.

17.
Nano Lett ; 16(10): 6058-6063, 2016 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-27588556

RESUMO

In the hydrogen evolution reaction (HER), the reactivity as a function of the hydrogen adsorption energy on different metal substrates follows a well-known volcano curve, peaked at the precious metal Pt. The goal of turning nonprecious metals into efficient catalysts for HER and other important chemical reactions is a fundamental challenge; it is also of technological significance. Here, we present results toward achieving this goal by exploiting the synergistic power of marginal catalysis and confined catalysis. Using density functional theory calculations, we first show that the volcano curve stays qualitatively intact when van der Waals attractions between a hydrogen adatom and different metal (111) surfaces are included. We further show that the hydrogen adsorption energy on the metal surfaces is weakened by 0.12-0.23 eV when hydrogen is confined between graphene and the metal surfaces, with Ni exhibiting the largest change. In particular, we find that the graphene-modified volcano curve peaks around Ni, whose bare surface already possesses moderate (or marginal) reactivity, and the corresponding HER rate of graphene-covered Ni is comparable to that of bare Pt. A hydrogen adatom has high mobility within the confined geometry. These findings demonstrate that graphene-covered Ni is an appealing effective, stable, and economical catalytic platform for HER.

18.
Cytotechnology ; 76(2): 217-229, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38495297

RESUMO

Cirrhosis is a familiar end-stage of multiple chronic liver diseases. The gene-modified mesenchymal stem cells (MSCs) have become one of the most promising schemes for the treatment of cirrhosis. MSCs exhibit their therapeutic role mainly by secreting hepatocyte growth factor (HGF). The aim of this research was to probe the anti-fibrosis role of exosomes secreted by HGF modified-mouse adipose MSCs (ADMSCs) on activated hepatic stellate cells (HSCs) and to preliminarily explore the possible mechanism. Firstly, mouse ADMSCs were isolated and identified. Quantitative real-time polymerase chain reaction verified the transfection efficiency of ADMSC transfected with HGF lentivirus. Exosomes derived from ADMSC transfecting negative control/HGF (ADMSCNC-Exo/ADMSCHGF-Exo) were extracted by density gradient centrifugation. HSCs were allocated to the control, TGF-ß, TGF-ß + ADMSC-Exo, TGF-ß + ADMSCNC-Exo, and TGF-ß + ADMSCHGF-Exo groups. Moreover, all mice were distributed to the control, CCl4 (40% CCl4 in olive oil), CCl4+ADMSC-Exo, CCl4+ADMSCNC-Exo, and CCl4+ADMSCHGF-Exo groups. Exosomes derived from ADMSCs with or without HGF transfection suppressed HSC activation, as evidenced by attenuating cell viability and cell cycle arrest at S phase but inducing apoptosis. Moreover, ADMSC-Exo, ADMSCNC-Exo, and ADMSCHGF-Exo effectively repressed the gene and protein levels of α-SMA, Col-I, Rho A, Cdc42, and Rac1 in TGF-ß-treated HSCs, and ADMSCHGF-Exo had the best effect. ADMSCHGF-Exo had a stronger regulatory effect on serum liver index than ADMSCNC-Exo in CCl4-induced mice. In conclusion, ADMSCHGF-Exo alleviated liver fibrosis by weakening the Rho pathway, thus reducing collagen production.

19.
Adv Mater ; 36(21): e2312597, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38301612

RESUMO

Thermochromism, the change in color of a material with temperature, is the fundamental basis of optical thermometry. A longstanding challenge in realizing sensitive optical thermometers for widespread use is identifying materials with pronounced thermometric optical performance in the visible range. Herein, it is demonstrated that single crystals of indium selenium iodide (InSeI), a 1D van der Waals (vdW) solid consisting of weakly bound helical chains, exhibit considerable visible range thermochromism. A strong temperature-dependent optical band edge absorption shift ranging from 450 to 530 nm (2.8 to 2.3 eV) over a 380 K temperature range with an experimental (dEg/dT)max value extracted to be 1.26 × 10-3 eV K-1 is shown. This value lies appreciably above most dense conventional semiconductors in the visible range and is comparable to soft lattice solids. The authors further seek to understand the origin of this unusually sensitive thermochromic behavior and find that it arises from strong electron-phonon interactions and anharmonic phonons that significantly broaden band edges and lower the Eg with increasing temperature. The identification of structural signatures resulting in sensitive thermochromism in 1D vdW crystals opens avenues in discovering low-dimensional solids with strong temperature-dependent optical responses across broad spectral windows, dimensionalities, and size regimes.

20.
Nat Commun ; 15(1): 332, 2024 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-38184667

RESUMO

The fine-tuning of topologically protected states in quantum materials holds great promise for novel electronic devices. However, there are limited methods that allow for the controlled and efficient modulation of the crystal lattice while simultaneously monitoring the changes in the electronic structure within a single sample. Here, we apply significant and controllable strain to high-quality HfTe5 samples and perform electrical transport measurements to reveal the topological phase transition from a weak topological insulator phase to a strong topological insulator phase. After applying high strain to HfTe5 and converting it into a strong topological insulator, we found that the resistivity of the sample increased by 190,500% and that the electronic transport was dominated by the topological surface states at cryogenic temperatures. Our results demonstrate the suitability of HfTe5 as a material for engineering topological properties, with the potential to generalize this approach to study topological phase transitions in van der Waals materials and heterostructures.

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