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1.
Dalton Trans ; 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36065901

RESUMO

Covalent attachment of molecules to metal oxide surfaces typically demands the presence of an anchoring group that in turn requires synthetic steps to introduce. BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) chromophores have long been used in dye-sensitized solar cells, but carboxylic acid groups typically had to be installed to act as surface anchors. We now find that even without the introduction of such anchors, the unmodified BODIPY can bind to TiO2 surfaces via its BF2 group through boron-oxygen surface bonds. Dipyrrin, the parent molecule of BODIPY, is also capable of binding directly to TiO2 surfaces, likely through its chelating nitrogen atoms. These binding modes prove to be even more robust than that of an installed carboxylate and offer a new way to attach molecular complexes to surfaces for (photo)catalytic applications since, once bound, we show that surface bound BODIPY and dipyrrin derivatives exhibit ultrafast photoinjection of electrons into the conduction band of TiO2.

2.
J Phys Condens Matter ; 34(46)2022 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-36063801

RESUMO

Compared to elemental gold (Au), Au-based alloys have attracted wide attention for their economy and superior performance stemming from their distinctive physicochemical properties. The study of the structural characterization for alloy materials remains one of the fundamental issues associated with their future applications essentially. In this work, we theoretically explore some typical intermetallic compounds of Au-based alloys under high pressure, which has been an effective means to generate intriguing crystal configurations with unexpected behaviors. Ourab initiosimulations find thatFd-3m-AuRb,Fd-3m-AuBa, andFd-3m-AuLa become stable above ∼10 GPa, andPmmn-AuAl becomes stable above ∼20 GPa. Further investigations of their compression behaviors reveal that the bulk moduli of Au-based alloys can be greatly reduced by combining alkali and alkaline earth metals. The present results have unraveled the high-pressure phases of Au-bearing compounds and provide insights for exploring their important compressibility that is strongly relevant to the containing non-Au elements.

3.
Free Radic Biol Med ; 190: 94-104, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35952922

RESUMO

The redox state is a crucial determinant of the maturation transition of cardiomyocytes in vivo. Mitochondria, the primary site of superoxide generation, are very sensitive to various stimulations, including oxygen and nutrient supply. How mitochondrial superoxide affects the differentiation and development of induced pluripotent stem cell (iPSC)-derived cardiac myocytes (iPS-CMs) is not completely clear. To address the questions, we monitored the superoxide level during the differentiation and development of human iPS-CMs using MitoSOX. Mitochondria-targeted antioxidant Mito-TEMPO was used to treat hiPS-CMs in the differentiation period. We found that mitochondrial superoxide generation was dramatically enhanced during the differentiation and early development of iPS-CMs. Increased oxidative stress induced oxidative damage to macromolecules in iPS-CMs, such as lipids, proteins, and DNA. Mito-TEMPO protected mitochondrial functions, alleviated oxidative damage to lipids, proteins, and DNA and improved cellular structure and fatty acid utilization. Our findings confirmed that iPS-CM suffered from oxidative stress during differentiation and that mitochondrial-targeted antioxidant is beneficial for the maturation of iPS-CMs.


Assuntos
Células-Tronco Pluripotentes Induzidas , Superóxidos , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Diferenciação Celular , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Lipídeos , Mitocôndrias/metabolismo , Miócitos Cardíacos/metabolismo , Superóxidos/metabolismo
4.
Phys Rev Lett ; 129(1): 016401, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35841573

RESUMO

Valence transition could induce structural, insulator-metal, nonmagnetic-magnetic and superconducting transitions in rare-earth metals and compounds, while the underlying physics remains unclear due to the complex interaction of localized 4f electrons as well as their coupling with itinerant electrons. The valence transition in the elemental metal europium (Eu) still has remained as a matter of debate. Using resonant x-ray emission scattering and x-ray diffraction, we pressurize the states of 4f electrons in Eu and study its valence and structure transitions up to 160 GPa. We provide compelling evidence for a valence transition around 80 GPa, which coincides with a structural transition from a monoclinic (C2/c) to an orthorhombic phase (Pnma). We show that the valence transition occurs when the pressure-dependent energy gap between 4f and 5d electrons approaches the Coulomb interaction. Our discovery is critical for understanding the electrodynamics of Eu, including magnetism and high-pressure superconductivity.

5.
Phys Chem Chem Phys ; 2022 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-35881443

RESUMO

The pressure-induced reaction between xenon (Xe) and other non-inert gas elements and the resultant crystal structures have attracted great interest. In this work, we carried out extensive simulations on the crystal structures of Xe-alkali metal (Xe-AM) systems under high pressures. Among all predicted compounds, KXe and RbXe are found to become stable at a pressure of ∼16 GPa by adopting a cubic symmetry of space group Pm3̄m. The stabilization of KXe and RbXe requires slightly lower pressure compared with that of previously reported CsXe (25 GPa), interestingly, which is in contrast to the electronegativity order of the AMs and unexpected. Our simulations also indicate that all predicted Xe compounds contain negatively charged Xe. Moreover, our in-depth analysis indicates that the occupation of AM d-orbitals plays a critical role in stabilizing these Xe-bearing compounds. These results shed light on the understanding of the reaction between Xe and AMs and the formation mechanism of the resultant crystal structures.

6.
J Am Chem Soc ; 144(29): 13394-13400, 2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35820372

RESUMO

Achieving room-temperature superconductivity has been an enduring scientific pursuit driven by broad fundamental interest and enticing potential applications. The recent discovery of high-pressure clathrate superhydride LaH10 with superconducting critical temperatures (Tc) of 250-260 K made it tantalizingly close to realizing this long-sought goal. Here, we report a remarkable finding based on an advanced crystal structure search method of a new class of extremely hydrogen-rich clathrate superhydride MH18 (M: rare-earth/actinide atom) stoichiometric compounds stabilized at an experimentally accessible pressure of 350 GPa. These compounds are predicted to host Tc up to 330 K, which is well above room temperature. The bonding and electronic properties of these MH18 clathrate superhydrides closely resemble those of atomic metallic hydrogen, giving rise to the highest Tc hitherto found in a thermodynamically stable hydride compound. An in-depth study of these extreme superhydrides offers insights for elucidating phonon-mediated superconductivity above room temperature in hydrogen-rich and other low-Z materials.

7.
Nat Commun ; 13(1): 3330, 2022 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-35680880

RESUMO

Sensitive detection of local acoustic vibrations at the nanometer scale has promising potential applications involving miniaturized devices in many areas, such as geological exploration, military reconnaissance, and ultrasound imaging. However, sensitive detection of weak acoustic signals with high spatial resolution at room temperature has become a major challenge. Here, we report a nanometer-scale system for acoustic detection with a single molecule as a probe based on minute variations of its distance to the surface of a plasmonic gold nanorod. This system can extract the frequency and amplitude of acoustic vibrations with experimental and theoretical sensitivities of 10 pm Hz-1/2 and 10 fm Hz-1/2, respectively. This approach provides a strategy for the optical detection of acoustic waves based on molecular spectroscopy without electromagnetic interference. Moreover, such a small nano-acoustic detector with 40-nm size can be employed to monitor acoustic vibrations or read out the quantum states of nanomechanical devices.


Assuntos
Ressonância de Plasmônio de Superfície , Vibração , Acústica , Nanotecnologia/métodos , Ressonância de Plasmônio de Superfície/métodos , Temperatura
8.
Cell Death Dis ; 13(5): 444, 2022 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35534453

RESUMO

Mitochondria are highly dynamic organelles that participate in ATP generation and involve calcium homeostasis, oxidative stress response, and apoptosis. Dysfunctional or damaged mitochondria could cause serious consequences even lead to cell death. Therefore, maintaining the homeostasis of mitochondria is critical for cellular functions. Mitophagy is a process of selectively degrading damaged mitochondria under mitochondrial toxicity conditions, which plays an essential role in mitochondrial quality control. The abnormal mitophagy that aggravates mitochondrial dysfunction is closely related to the pathogenesis of many diseases. As the myocardium is a highly oxidative metabolic tissue, mitochondria play a central role in maintaining optimal performance of the heart. Dysfunctional mitochondria accumulation is involved in the pathophysiology of cardiovascular diseases, such as myocardial infarction, cardiomyopathy and heart failure. This review discusses the most recent progress on mitophagy and its role in cardiovascular disease.


Assuntos
Doenças Cardiovasculares , Autofagia , Doenças Cardiovasculares/patologia , Homeostase , Humanos , Mitocôndrias/metabolismo , Mitofagia/fisiologia
9.
J Am Chem Soc ; 144(19): 8449-8453, 2022 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-35535858

RESUMO

Electrocatalytic ammonia oxidation at room temperature and pressure allows energy-economical and environmentally friendly production of nitrites and nitrates. Few molecular catalysts, however, have been developed for this six- or eight-electron oxidation process. We now report [Cu(bipyalk)]+, a homogeneous electrocatalyst that realizes the title reaction in water at 94% Faradaic efficiency. The catalyst exhibits high selectivity against water oxidation in aqueous media, as [Cu(bipyalk)]+ is not competent for water oxidation.


Assuntos
Nitratos , Nitritos , Amônia , Cobre , Óxidos de Nitrogênio , Oxirredução , Água
10.
Cell Discov ; 8(1): 40, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35504898

RESUMO

Ferroptosis is a regulated iron-dependent cell death characterized by the accumulation of lipid peroxidation. A myriad of facets linking amino acid, lipid, redox, and iron metabolisms were found to drive or to suppress the execution of ferroptosis. However, how the cells decipher the diverse pro-ferroptotic stress to activate ferroptosis remains elusive. Here, we report that protein O-GlcNAcylation, the primary nutrient sensor of glucose flux, orchestrates both ferritinophagy and mitophagy for ferroptosis. Following the treatment of ferroptosis stimuli such as RSL3, a commonly used ferroptosis inducer, there exists a biphasic change of protein O-GlcNAcylation to modulate ferroptosis. Pharmacological or genetic inhibition of O-GlcNAcylation promoted ferritinophagy, resulting in the accumulation of labile iron towards mitochondria. Inhibition of O-GlcNAcylation resulted in mitochondria fragmentation and enhanced mitophagy, providing an additional source of labile iron and rendering the cell more sensitive to ferroptosis. Mechanistically, we found that de-O-GlcNAcylation of the ferritin heavy chain at S179 promoted its interaction with NCOA4, the ferritinophagy receptor, thereby accumulating labile iron for ferroptosis. Our findings reveal a previously uncharacterized link of dynamic O-GlcNAcylation with iron metabolism and decision-making for ferroptosis, thus offering potential therapeutic intervention for fighting disease.

11.
Phys Rev Lett ; 128(18): 186001, 2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-35594097

RESUMO

There is great current interest in multicomponent superhydrides due to their unique quantum properties under pressure. A remarkable example is the ternary superhydride Li_{2}MgH_{16} computationally identified to have an unprecedented high superconducting critical temperature T_{c} of ∼470 K at 250 GPa. However, the very high synthesis pressures required remains a significant hurdle for detailed study and potential applications. In this Letter, we evaluate the feasibility of synthesizing ternary Li-Mg superhydrides by the recently proposed pressure-potential (P^{2}) method that uniquely combines electrochemistry and applied pressure to control synthesis and stability. The results indicate that it is possible to synthesize Li-Mg superhydrides at modest pressures by applying suitable electrode potentials. Using pressure alone, no Li-Mg ternary hydrides are predicted to be thermodynamically stable, but in the presence of electrode potentials, both Li_{2}MgH_{16} and Li_{4}MgH_{24} can be stabilized at modest pressures. Three polymorphs are predicted as ground states of Li_{2}MgH_{16} below 300 GPa, with transitions at 33 and 160 GPa. The highest pressure phase is superconducting, while the two at lower pressures are not. Our findings point out the potentially important role of the P^{2} method in controlling phase stability of complex multicomponent superhydrides.

12.
Phys Rev Lett ; 128(16): 167001, 2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35522494

RESUMO

The recent discovery of superconductive rare earth and actinide superhydrides has ushered in a new era of superconductivity research at high pressures. This distinct type of clathrate metal hydrides was first proposed for alkaline-earth-metal hydride CaH_{6} that, however, has long eluded experimental synthesis, impeding an understanding of pertinent physics. Here, we report successful synthesis of CaH_{6} and its measured superconducting critical temperature T_{c} of 215 K at 172 GPa, which is evidenced by a sharp drop of resistivity to zero and a characteristic decrease of T_{c} under a magnetic field up to 9 T. An estimate based on the Werthamer-Helfand-Hohenberg model gives a giant zero-temperature upper critical magnetic field of 203 T. These remarkable benchmark superconducting properties place CaH_{6} among the most outstanding high-T_{c} superhydrides, marking it as the hitherto only clathrate metal hydride outside the family of rare earth and actinide hydrides. This exceptional case raises great prospects of expanding the extraordinary class of high-T_{c} superhydrides to a broader variety of compounds that possess more diverse material features and physics characteristics.

13.
Psychopharmacology (Berl) ; 239(9): 2799-2807, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35579686

RESUMO

BACKGROUND: The effects of sevoflurane anesthesia on childhood neurodevelopment and adult brain function have attracted increasing scientific attentions. However, the exact mechanisms underlying hyperphosphorylation of tau protein in sevoflurane induced abnormalities in central nervous system (CNS) development, particularly in the hippocampus, have not been fully determined. METHODS: We utilized molecular biological and behavioral approaches to compare the changes in cognitive function in mice exposed to repeated sevoflurane during the neonatal stage, and to assess whether PP2A-associated tau hyperphosphorylation is involved in sevoflurane induced neonatal neurotoxicity. RESULTS: We reported that mice anesthetized with repeated sevoflurane during the neonatal period caused cognitive dysfunction during the adulthood. More importantly, we found that hyperphosphorylation of tau protein and decreased level of protein phosphatase 2A (PP2A) were detected in the hippocampus of mice after neonatal exposure of sevoflurane. Meanwhile, GSK-3ß activity was found to be increased with repeated sevoflurane exposure, but not for more than 2 weeks. CONCLUSION: Our results suggest that PP2A-associated hyperphosphorylation of tau protein might contribute to sevoflurane induced developmental neurotoxicity. These findings could provide a theoretical basis for the safely usage of sevoflurane in pediatric surgeries, and offer a valuable reference and potential therapeutic targets for the development of neuroprotective drugs.


Assuntos
Proteína Fosfatase 2 , Sevoflurano , Proteínas tau , Animais , Animais Recém-Nascidos , Encéfalo , Glicogênio Sintase Quinase 3 beta/metabolismo , Hipocampo , Camundongos , Fosforilação , Proteína Fosfatase 2/metabolismo , Sevoflurano/toxicidade , Proteínas tau/metabolismo
14.
J Phys Condens Matter ; 34(29)2022 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-35477172

RESUMO

As one of the most prototypicalAX2-type compounds, barium halide shared the cubic structure withFm-3msymmetry for BaCl2or orthorhombic structure withPnmasymmetry for BaBr2at ambient pressure. In this work, we explored the crystal structures of BaCl2and BaBr2under high pressure. We predicted a thermodynamically more favored structure with orthorhombicCmcmsymmetry for both BaCl2and BaBr2, at 74 and 47 GPa, respectively. Our simulations reveal that the metallic feature ofCmcmBaCl2andCmcmBaBr2under high pressure. The present results improve the understanding of high-pressure structures ofAX2compounds at extremely high-pressure conditions.

15.
Nano Lett ; 22(9): 3691-3698, 2022 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-35451303

RESUMO

Synthetic polymer-derived hollow carbon spheres have great utilitarian value in many fields for which the synthesis of proper polymer precursors is a key process. The exploration of new suitable polymer precursors and the construction of refined hollow structures in emerging polymers are both of great significance for synthetic methodology and novel carbon materials. Here, for the first time Schiff base polymer (SBP) colloid spheres with refined hollow structures were synthesized by tandem gradient growth and confined polymerization processes. The Hill equation was employed as a mathematical model to explain the gradient growth of SBP spheres. The size-dependent inner structure of SBP spheres can be adjusted from hollow to multichamber-surrounded hollow, and then to a multichamber structure. SBP-derived carbon spheres having similar surface area and chemical composition but different inner structures provide an effective way to investigate the relationship between inner structure and performance.


Assuntos
Carbono , Polímeros , Carbono/química , Microesferas , Polimerização , Polímeros/química , Bases de Schiff
17.
PeerJ ; 10: e13087, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35291483

RESUMO

Background: As a fundamental metabolism, leaf photosynthesis not only provides necessary energy for plant survival and growth but also plays an important role in global carbon fixation. However, photosynthesis is highly susceptible to environmental stresses and can be significantly influenced by future climate change. Methods: In this study, we examined the photosynthetic responses of Phragmites australis (P. australis) to three precipitation treatments (control, decreased 30%, and increased 30%) under two thermal regimes (ambient temperature and +4 °C) in environment-controlled chambers. Results: Our results showed that the net CO2 assimilation rate (P n), maximal rate of Rubisco (V cmax), maximal rate of ribulose-bisphosphate (RuBP) regeneration (J max) and chlorophyll (Chl) content were enhanced under increased precipitation condition, but were declined drastically under the condition of water deficit. The increased precipitation had no significant effect on malondialdehyde (MDA) content (p > 0.05), but water deficit drastically enhanced the MDA content by 10.1%. Meanwhile, a high temperature inhibited the positive effects of increased precipitation, aggravated the adverse effects of drought. The combination of high temperature and water deficit had more detrimental effect on P. australis than a single factor. Moreover, non-stomatal limitation caused by precipitation change played a major role in determining carbon assimilation rate. Under ambient temperature, Chl content had close relationship with P n (R2 = 0.86, p < 0.01). Under high temperature, P n was ralated to MDA content (R2 = 0.81, p < 0.01). High temperature disrupted the balance between V cmax and J max (the ratio of J max to V cmax decreased from 1.88 to 1.12) which resulted in a negative effect on the photosynthesis of P. australis. Furthermore, by the analysis of Chl fluorescence, we found that the xanthophyll cycle-mediated thermal dissipation played a major role in PSII photoprotection, resulting in no significant change on actual PSII quantum yield (Φ PSII) under both changing precipitation and high temperature conditions. Conclusions: Our results highlight the significant role of precipitation change in regulating the photosynthetic performance of P. australis under elevated temperature conditions, which may exacerbate the drought-induced primary productivity reduction of P. australis under future climate scenarios.

18.
Bioorg Chem ; 121: 105704, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35240418

RESUMO

In order to search for novel checkpoint kinase 1/2 (Chk1) inhibitors, we have designed and synthesized a series of new compounds incorporating thienopyridazine core. Bioevaluation showed that compounds 10j, 10i, 13e and 10o exhibited relatively good inhibitory activity. Notably, compound 10o displayed high selectivity against a panel of kinases and inhibited Chk1/2 signaling pathway stimulated by DNA damage drugs in cellular level. Molecular docking of 10o to the ATP-binding site of Chk1 kinase domain indicated the existence of polar interactions between 10o and the ATP-ribose-binding residues of Chk1. In mouse HT-29 xenografts, a synergistic effect was observed. Co-treatment by CPT-11 and 10o significantly diminished the tumor volume, indicating the great potential of 10o as a candidate of Chk1/2 inhibitor.


Assuntos
Dano ao DNA , Inibidores de Proteínas Quinases , Trifosfato de Adenosina , Animais , Sítios de Ligação , Humanos , Camundongos , Simulação de Acoplamento Molecular , Inibidores de Proteínas Quinases/química
19.
J Phys Chem Lett ; 13(10): 2371-2378, 2022 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-35254074

RESUMO

Nonblinking colloidal quantum dots (QDs) are significant to their applications as single-photon sources or light-emitting materials. Herein, a simple heat-up method was developed to synthesize high-qualityWZ-CdSe/CdS core-shell colloidal QDs, which achieved a near-unity photoluminescence quantum yield (PLQY). It was found that the blinking behavior of such QDs was completely suppressed at high excitation intensities, and ultra-stable PL emission was observed. For this reason, a systematic investigation was conducted, revealing that the complete blinking suppression was attributed mainly to the efficient multiexciton emission at high excitation intensities. Such high-quality QDs with nonblinking behaviors and nearly ideal PL properties at high excitation intensities have massive potential applications in various robust conditions, including QD display screens, single-particle tracks, and single-photon sources.

20.
Front Microbiol ; 13: 820539, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35211105

RESUMO

Predicting the number of microorganisms has excellent application in the food industry. It helps in predicting and managing the storage time and food safety. This study aimed to establish a new, simple, and effective model for predicting the number of microorganisms. The dimensional analysis model (DAM) was established based on dimensionless analysis and the Pi theorem. It was then applied to predict the number of Pseudomonas in Niuganba (NGB), a traditional Chinese fermented dry-cured beef, which was prepared and stored at 278 K, 283 K, and 288 K. Finally, the internal and external validation of the DAM was performed using six parameters including R 2, R 2 adj , root mean square error (RMSE), standard error of prediction (%SEP), A f , and B f . High R 2 and R 2 adj and low RMSE and %SEP values indicated that the DAM had high accuracy in predicting the number of microorganisms and the storage time of NGB samples. Both A f and B f values were close to 1. The correlation between the observed and predicted numbers of Pseudomonas was high. The study showed that the DAM was a simple, unified and effective model to predict the number of microorganisms and storage time.

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