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1.
Nature ; 589(7842): 396-401, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33473229

RESUMO

The water-gas shift (WGS) reaction is an industrially important source of pure hydrogen (H2) at the expense of carbon monoxide and water1,2. This reaction is of interest for fuel-cell applications, but requires WGS catalysts that are durable and highly active at low temperatures3. Here we demonstrate that the structure (Pt1-Ptn)/α-MoC, where isolated platinum atoms (Pt1) and subnanometre platinum clusters (Ptn) are stabilized on α-molybdenum carbide (α-MoC), catalyses the WGS reaction even at 313 kelvin, with a hydrogen-production pathway involving direct carbon monoxide dissociation identified. We find that it is critical to crowd the α-MoC surface with Pt1 and Ptn species, which prevents oxidation of the support that would cause catalyst deactivation, as seen with gold/α-MoC (ref. 4), and gives our system high stability and a high metal-normalized turnover number of 4,300,000 moles of hydrogen per mole of platinum. We anticipate that the strategy demonstrated here will be pivotal for the design of highly active and stable catalysts for effective activation of important molecules such as water and carbon monoxide for energy production.

2.
Endoscopy ; 56(5): 334-342, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38412993

RESUMO

BACKGROUND: Inaccurate Forrest classification may significantly affect clinical outcomes, especially in high risk patients. Therefore, this study aimed to develop a real-time deep convolutional neural network (DCNN) system to assess the Forrest classification of peptic ulcer bleeding (PUB). METHODS: A training dataset (3868 endoscopic images) and an internal validation dataset (834 images) were retrospectively collected from the 900th Hospital, Fuzhou, China. In addition, 521 images collected from four other hospitals were used for external validation. Finally, 46 endoscopic videos were prospectively collected to assess the real-time diagnostic performance of the DCNN system, whose diagnostic performance was also prospectively compared with that of three senior and three junior endoscopists. RESULTS: The DCNN system had a satisfactory diagnostic performance in the assessment of Forrest classification, with an accuracy of 91.2% (95%CI 89.5%-92.6%) and a macro-average area under the receiver operating characteristic curve of 0.80 in the validation dataset. Moreover, the DCNN system could judge suspicious regions automatically using Forrest classification in real-time videos, with an accuracy of 92.0% (95%CI 80.8%-97.8%). The DCNN system showed more accurate and stable diagnostic performance than endoscopists in the prospective clinical comparison test. This system helped to slightly improve the diagnostic performance of senior endoscopists and considerably enhance that of junior endoscopists. CONCLUSION: The DCNN system for the assessment of the Forrest classification of PUB showed satisfactory diagnostic performance, which was slightly superior to that of senior endoscopists. It could therefore effectively assist junior endoscopists in making such diagnoses during gastroscopy.


Assuntos
Úlcera Péptica Hemorrágica , Humanos , Úlcera Péptica Hemorrágica/diagnóstico , Úlcera Péptica Hemorrágica/classificação , Estudos Retrospectivos , Masculino , Pessoa de Meia-Idade , Feminino , Inteligência Artificial , Redes Neurais de Computação , Curva ROC , Estudos Prospectivos , Idoso , Gravação em Vídeo , Gastroscopia/métodos , Reprodutibilidade dos Testes , Adulto
3.
Langmuir ; 40(20): 10663-10675, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38718299

RESUMO

Electrocatalytic reduction (ECR) of CO2 to chemical products is an important carbon emission reduction method. This work uses DFT to study the stability of N-doped graphene-supported four metal single-atom catalysts (M-N-C) and the effects of the coordination environment and metal centers on the selectivity of CO2 ECR to C1 products. The results show that Fe, Co, Ni, and Cu have good stability. The coordination environment has a significant modulating effect on product selectivity, and the change of the number of ligand nitrogen atoms will affect the size of the potential-limiting step of each product. When the number of nitrogen ligands is the same, the different metal centers of the M-N-C catalyst have a significant effect on the selectivity of different products. In addition, the introduction of nitrogen atom ligands can adjust the electronic structure of the graphene-supported metal center, increase the d-band center of most metals, and improve the reaction activity.

4.
Phys Chem Chem Phys ; 26(6): 5704-5712, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38289691

RESUMO

In Fischer-Tropsch synthesis (FTS), the cobalt catalyst has higher C5+ and lower CH4 selectivity in the hcp phase than in the fcc phase. However, a detailed explanation of the intrinsic mechanism is still missing. The underlying reason was explored combining density functional theory, Wulff construction, and a particle-level descriptor based on the slab model of surfaces that are prevalent in the Wulff shape to provide single-particle level understanding. Using a particle-level indicator of the reaction rates, we have shown that it is more difficult to form CH4 on hcp-Co than on fcc-Co, due to the larger effective barrier difference of CH4 formation and C-C coupling on hcp-Co particles, which leads to the lower CH4 selectivity of hcp-Co in FTS. Among the exposed facets of fcc-Co, the (311) surface plays a pivotal role in promoting CH4 formation. The reduction of CH4 selectivity in cobalt-based FTS is achievable through phase engineering of Co from fcc to hcp or by tuning the temperature and size of the particles.

5.
Phys Chem Chem Phys ; 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38946600

RESUMO

Using gas phase Fourier-transform microwave spectroscopy complemented by theoretical analysis, this study delivers a comprehensive depiction of the physical origin of the 'n → π* interaction' between CO2 and acrolein, one of the most reactive aldehydes. Three distinct isomers of the acrolein-CO2 complex, linked through a C⋯O tetrel bond (or n → π* interaction) and a C-H⋯O hydrogen bond, have been unambiguously identified in the pulsed jet. Relative intensity measurements allowed estimation on the population ratio of the three isomers to be T1/T2/C1 ≈ 25/5/1. Advanced theoretical analyses were employed to elucidate the intricacies of the noncovalent interactions within the examined complex. This study not only sheds light on the molecular underpinnings of n → π* interactions but also paves the way for future exploration in carbon dioxide capture and utilization, leveraging the fundamental principles uncovered in the study of acrolein-carbon dioxide interactions.

6.
Environ Geochem Health ; 46(2): 39, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38227107

RESUMO

To investigate the heavy metals (HMs) contamination of surface farmland soil along the river in the southeast of a mining area in southwest China and identify the contamination sources, 54 topsoil samples were collected and the concentrations of seven elements (Zn, Ni, Pb, Cu, Hg, Cr, and Co) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic fluorescence spectrometry (AFS). The geo-accumulation index ([Formula: see text]) and comprehensive potential ecological risk index ([Formula: see text]) were used for analysis to determine the pollution degree of HMs and the risk level of the study area. Meanwhile, the Positive Matrix Factorization (PMF) model was combined with a variety of statistical methods to determine the sources of HMs. To explore the influence of the river flowing through the mining area on the concentrations of HMs in the farmland soil, 15 water samples were collected and the concentrations of the above seven elements were determined. The results showed that the concentrations of Pb, Cu, and Zn in soil all exceeded the risk screening value, and Pb in soil of some sampling sites exceeded control value of "Agricultural Land Soil Pollution Risk Control Standard".[Formula: see text] showed that Pb was heavily contaminated, while Cu and Zn were moderately contaminated. RI showed that the study area was at moderate risk. PMF and various statistical methods showed that the main source of HMs was the industrial source. In the short term, the river flowing through the mine has no significant influence on the concentration of HMs in the soil. The results provide a reference for the local government to control contamination and identify the sources of HMs.


Assuntos
Metais Pesados , Solo , Fazendas , Rios , Chumbo , Medição de Risco , China
7.
Angew Chem Int Ed Engl ; 63(12): e202318747, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38270973

RESUMO

Metal atoms on the support serve as active sites for many heterogeneous catalysts. However, the active metal sites on the support are conventionally described as static, and the intermediates adsorbed on the support far away from the active metal sites cannot be transformed. Herein, we report the first example of operando mobile catalysis to promote catalytic efficiency by enhancing the collision probability between active sites and reactants or reaction intermediates. Specifically, ligand-coordinated Pt single atoms (isolated MeCpPt- species) are bonded on CeO2 and transformed into mobile MeCpPt(H)CO complexes during the reverse water gas shift reaction for operando mobile catalysis. This strategy enables the conversion of inert carbonate intermediates on the CeO2 support. A turnover frequency (TOF) of 6358 mol CO2 molPt -1 ⋅ h-1 and 99 % CO selectivity at 300 °C is obtained for reverse water gas shift reaction, dramatically higher than those of Pt catalysts reported in the literature. Operando mobile catalysis presents a promising strategy for designing high-efficiency heterogeneous catalysts for various chemical reactions and applications.

8.
J Am Chem Soc ; 145(9): 5353-5362, 2023 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-36853085

RESUMO

Photocatalysis provides an eco-friendly route for the hydrogenation of aromatic carbonyls to O-free aromatics, which is an important refining process in the chemical industry that is generally carried out under high pressure of hydrogen at elevated temperatures. However, aromatic carbonyls are often only partially hydrogenated to alcohols, which readily desorbs and are hardly further deoxygenated under ambient conditions. Here, we show that by constructing an oxide surface over the Pd cocatalyst supported on graphitic carbon nitride, an alternative hydrogenation path of aromatic carbonyls becomes available via a step-wise acetalization and hydrogenation, thus allowing efficient and selective production of O-free aromatics. The PdO surface allows for optimum adsorption of reactants and intermediates and rapid abstraction of hydrogen from the alcohol donor, favoring fast acetalization of the carbonyls and their consecutive hydrogenation to O-free hydrocarbons. The photocatalytic hydrogenation of benzaldehyde into toluene shows a high selectivity of >90% and a quantum efficiency of ∼10.2% under 410 nm irradiation. By adding trace amounts of HCl to the reaction solution, the PdO surface remains stable and active for long-term operation at high concentrations, offering perspective for practical applications.

9.
J Am Chem Soc ; 145(34): 18748-18752, 2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37606281

RESUMO

In this study, single Ni2 clusters (two Ni atoms bridged by a lattice oxygen) are successfully synthesized on monolayered CuO. They exhibit a remarkable activity toward low-temperature CO2 thermal dissociation, in contrast to cationic Ni atoms that nondissociatively adsorb CO2 and metallic Ni ones that are chemically inert for CO2 adsorption. Density functional theory calculations reveal that the Ni2 clusters can significantly alter the spatial symmetry of their unoccupied frontier orbitals to match the occupied counterpart of the CO2 molecule and enable its low-temperature dissociation. This study may help advance single-cluster catalysis and exploit the unexcavated mechanism for low-temperature CO2 activation.

10.
J Am Chem Soc ; 145(38): 20936-20942, 2023 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-37703050

RESUMO

The exploration of non-noble metal catalysts for alkane dehydrogenation and their catalytic mechanisms is the priority in catalysis research. Here, we report a high-density coordinatively unsaturated Zn cation (Zncus) catalyst for the direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). The catalyst demonstrated good catalytic performance (∼40% initial EB conversion rate and >98% ST selectivity) and excellent regeneration ability in the reaction, which is attributed to the high-density (HD) distribution and high-stability structure of Zncus active sites on the surface of zinc silicate (HD-Zncus@ZS). Density functional theory (DFT) calculations further illustrated the reaction pathway and intermediates, supporting that the Zncus sites can efficiently activate the C-H bond of ethyl on ethylbenzene. Developing the high-density Zncus catalyst and exploring the catalytic mechanism laid a good foundation for designing practical non-noble metal catalysts.

11.
Prostate ; 83(5): 470-486, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36576015

RESUMO

BACKGROUND: Like DNA methylation, histone modifications are considered important processes for epigenetic alterations in gene function, and abnormally high expression of histone deacetylases (HDACs) plays a key role in many human diseases. In addition to regulating the acetylation levels of histone and non-histone proteins and gene transcription, HDAC inhibitors as antitumor drugs can also affect the DNA damage repair (DDR) pathway in tumor cells. Prostate cancer (PCa) is one of the most heritable malignancies in which DDR pathway defects can be detected in a considerable proportion of cases. Such defects are more prevalent in castration-resistant prostate cancer (CRPC) and are highly enriched in metastatic lesions. There is currently evidence that DDR pathway-deficient PCa is associated with high-risk biological behaviors and response sensitivity to platinum-based chemotherapy. Platinum-based drugs have been used in multiple clinical trials as monotherapy or in combination with other chemotherapeutic agents for the treatment of CRPC. METHODS: This study evaluated the combined anticancer effect of (cisplatin) CDDP and the HDAC inhibitors vorinostat (SAHA) on three androgen-dependent cell lines PC-3, DU-145, and C4-2B in vitro. The efficacy and safety of SAHA combined with CDDP in the treatment of CRPC were further verified through animal experiments. RESULTS: The combination of the two drugs increases cytotoxic effects by increasing DNA damage. Our results showed that the SAHA could not only reduce the expression of homologous recombinant repair proteins BRCA2, BRCA1, PARP1, and RAD51, but also decrease enzymes that Reduce the key enzymes of GSH biosynthesis, GSS and GCLC, and GSTP1 which can catalyze the binding of GSH to cisplatin. The intracellular GSH level also decreased with the increase of SAHA concentration, at the same time, the content of intracellular Pt element. CONCLUSION: The combination of CDDP and SAHA can produce synergistic anticancer effects in androgen-independent PCa cells in vitro and in vivo. Our results open up a new avenue for the effective treatment of CRPC. To optimize the chemotherapy regimen for patients with advanced PCa, it is necessary to further study the molecular mechanism of platinum drugs, HDAC inhibitors, and their combined action.


Assuntos
Antineoplásicos , Neoplasias de Próstata Resistentes à Castração , Masculino , Animais , Humanos , Vorinostat/farmacologia , Cisplatino , Inibidores de Histona Desacetilases/farmacologia , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Androgênios , Linhagem Celular Tumoral , Antineoplásicos/farmacologia , Dano ao DNA
12.
NMR Biomed ; 36(10): e4994, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37392148

RESUMO

Renal metabolism is essential for kidney functions and energy homeostasis in the body. The TCA cycle is the hub of metabolism, but the metabolic activities of the cycle in the kidney have rarely been investigated. This study is to assess metabolic processes at the level of the TCA cycle in the kidney based on isotopomer distributions in multiple metabolites. Isolated rat kidneys were perfused with media containing common substrates including lactate and alanine for an hour. One group of kidneys received [U-13 C3 ]lactate instead of natural abundance lactate while the other group received [U-13 C3 ]alanine instead of natural abundance alanine. Perfused kidneys and effluent were prepared for analysis using NMR spectroscopy. 13 C-labeling patterns in glutamate, fumarate, aspartate and succinate from the kidney extracts showed that pyruvate carboxylase and oxidative metabolism through the TCA cycle were comparably very active, but pyruvate cycling and pyruvate dehydrogenase were relatively less active. Isotopomer analyses with fumarate and malate from effluent, however, indicated that pyruvate carboxylase was much more active than the TCA cycle and other metabolic processes. The reverse equilibrium of oxaloacetate with four-carbon intermediates of the cycle was nearly complete (92%), based on the ratio of [2,3,4-13 C3 ]/[1,2,3-13 C3 ] in aspartate or malate. 13 C enrichment in glucose with 13 C-lactate supply was higher than that with 13 C-alanine. Isotopomer analyses with multiple metabolites (i.e., glutamate, fumarate, aspartate, succinate and malate) allowed us to assess relative metabolic processes in the TCA cycle in the kidney supplied with [U-13 C3 ]lactate. Data from the analytes were generally consistent, indicating highly active pyruvate carboxylase and oxidative metabolism through the TCA cycle. Different 13 C-labeling patterns in analytes from the kidney extracts versus effluent suggested metabolic compartmentalization.


Assuntos
Ciclo do Ácido Cítrico , Malatos , Ratos , Animais , Malatos/metabolismo , Piruvato Carboxilase/metabolismo , Ácido Aspártico/metabolismo , Glucose/metabolismo , Ácido Glutâmico/metabolismo , Ácido Pirúvico/metabolismo , Ácido Láctico , Succinatos , Alanina/metabolismo , Isótopos de Carbono/metabolismo
13.
NMR Biomed ; 36(3): e4857, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36285844

RESUMO

Kidneys play a central role in numerous disorders but current imaging methods have limited utility to probe renal metabolism. Hyperpolarized (HP) 13 C magnetic resonance imaging is uniquely suited to provide metabolite-specific information about key biochemical pathways and it offers the further advantage that renal imaging is practical in humans. This study evaluated the feasibility of hyperpolarization examinations in a widely used model for analysis of renal physiology, the isolated kidney, which enables isolation of renal metabolism from the effects of other organs and validation of HP results by independent measurements. Isolated rat kidneys were supplied with either HP [1-13 C]pyruvate only or HP [1-13 C]pyruvate plus octanoate. Metabolic activity in both groups was confirmed by stable renal oxygen consumption. HP [1-13 C]pyruvate was readily metabolized to [13 C]bicarbonate, [1-13 C]lactate, and [1-13 C]alanine, detectable seconds after HP [1-13 C]pyruvate was injected. Octanoate suppressed but did not eliminate the production of HP [13 C]bicarbonate from [1-13 C]pyruvate. Steady-state flux analyses using non-HP 13 C substrates validated the utilization of HP [1-13 C]pyruvate, as observed by HP 13 C NMR. In the presence of octanoate, lactate is generated from a tricarboxylic acid cycle intermediate, oxaloacetate. The isolated rat kidney may serve as an excellent model for investigating and establishing new HP 13 C metabolic probes for future kidney imaging applications.


Assuntos
Caprilatos , Ácido Pirúvico , Ratos , Humanos , Animais , Ácido Pirúvico/metabolismo , Bicarbonatos/metabolismo , Rim/diagnóstico por imagem , Rim/metabolismo , Ácido Láctico/metabolismo , Isótopos de Carbono/metabolismo
14.
Liver Int ; 43(8): 1729-1740, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37183518

RESUMO

BACKGROUND AND AIMS: Steatosis is the early pathological change in alcohol-associated liver disease. However, its precise mechanism is still unclear. The present study is aimed to explore the role and mechanism of acetyl-CoA synthetase 2 (ACSS2) in acute alcohol-induced lipogenesis. METHODS: The increase in ACSS2 nuclear import and histone H3 acetylation were observed in mice after intraperitoneally injected with 2 g/kg ethanol or oral administration of 5 g/kg ethanol and also validated in hepatocytes stimulated with ethanol or acetate. The role of ACSS2 was further explored in liver-specific ACSS2 knockdown mice fed with ethanol-containing diet. RESULTS: Alcohol challenge induced hepatic lipid deposition and upregulated lipogenic genes in mice. It also promoted ACSS2 nuclear import and increased histone H3 acetylation. In hepatocytes, ethanol induced similar phenomena whereas ACSS2 knockdown blocked histone acetylation and lipogenic gene induction. P300/CBP associated factor (PCAF), but not general control nonderepressible 5, CREB-binding protein (CBP) and p300, facilitated H3K9 acetylation responding to ethanol challenge. CUT&RUN assay showed the enrichment of acetylated histone H3K9 surrounding Fasn and Acaca promoters. These results indicated that ethanol metabolism promoted ACSS2 nuclear import to support lipogenesis via H3K9 acetylation. In alcohol-feeding mice, liver-specific ACSS2 knockdown blocked the interaction between PCAF and H3K9 and suppressed lipogenic gene induction in the liver, demonstrating the critical role of ACSS2 in lipogenesis. CONCLUSIONS: Our study demonstrated that alcohol metabolism generated acetyl-CoA in the nucleus dependently on nuclear ACSS2, contributing to epigenetic regulation of lipogenesis in hepatic steatosis. Targeting ACSS2 may be a potential therapeutical strategy for acute alcoholic liver steatosis.


Assuntos
Acetato-CoA Ligase , Fígado Gorduroso Alcoólico , Fígado Gorduroso , Hepatopatias Alcoólicas , Animais , Camundongos , Acetilcoenzima A/genética , Acetilcoenzima A/metabolismo , Epigênese Genética , Etanol , Fígado Gorduroso/genética , Fígado Gorduroso Alcoólico/genética , Histonas , Lipogênese/genética , Fígado/metabolismo , Hepatopatias Alcoólicas/metabolismo , Acetato-CoA Ligase/genética , Acetato-CoA Ligase/metabolismo
15.
Phys Chem Chem Phys ; 25(5): 4313-4322, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36688704

RESUMO

The carbonization of iron is a very important early phenomenon in the field of heterogeneous catalysis and the petrochemical industry, but the mechanism is still controversial. In this work, the carbonization mechanism and carbonization structure of iron nanoparticles by different carbon sources (CH4, C2H6, C2H4, C2H2) were systematically investigated using the reactive molecular dynamics method. The results show that saturated alkanes are dehydrogenated while adsorbed, but unsaturated olefins and alkynes undergo bond-breaking while adsorbed. The C-H bond is more likely to break than the C-C bond. Hydrocarbons with high carbon content have a strong ability to carbonize Fe nanoparticles under the same conditions. For C2H4 and C2H2, the C atoms generated from dissociation form a large number of long carbon chains intertwined with branched chains and multiple carbon rings. The C2 species formed by C2H2 after complete dehydrogenation diffuse rapidly to the interior of the nanoparticles, releasing the surface active sites and accelerating the carbonization process. Carbon-rich iron carbides (FeCx) with different Fe/C ratios were obtained by carbonization with different carbon sources. In addition, the Fe(110) surface exhibits the strongest carburizing ability. These findings provide systematic insights into the initial stages of metal Fe carburization.

16.
J Phys Chem A ; 127(9): 2071-2080, 2023 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-36849363

RESUMO

Iron carbides have attracted increasing attention in recent years due to their enormous potential in catalytic fields, such as Fischer-Tropsch synthesis and the growth of carbon nanotubes. Theoretical calculations can provide a more thorough understanding of these reactions at the atomic scale. However, due to the extreme complexity of the active phases and surface structures of iron carbides at the operando conditions, calculations based on density functional theory (DFT) are too costly for realistically large models of iron carbide particles. Therefore, a cheap and efficient quantum mechanical simulation method with accuracy comparable to DFT is desired. In this work, we adopt the spin-polarized self-consistent charge density functional tight-binding (DFTB2) method for iron carbides by reparametrization of the repulsive part of the Fe-C interactions. To assess the performance of the improved parameters, the structural and electronic properties of iron carbide bulks and clusters obtained with DFTB2 method are compared with the previous experimental values and the results obtained with DFT approach. Calculated lattice parameters and density of states are close to DFT predictions. The benchmark results show that the proposed parametrization of Fe-C interactions provides transferable and balanced description of iron carbide systems. Therefore, spin-polarized DFTB2 is valued as an efficient and reliable method for the description of iron carbide systems.

17.
Nature ; 544(7648): 80-83, 2017 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-28329760

RESUMO

Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM). This method requires less energy, and the simpler and more compact device design allows direct integration into PEMFC stacks. There remains, however, the need for an efficient APRM catalyst. Here we report that platinum (Pt) atomically dispersed on α-molybdenum carbide (α-MoC) enables low-temperature (150-190 degrees Celsius), base-free hydrogen production through APRM, with an average turnover frequency reaching 18,046 moles of hydrogen per mole of platinum per hour. We attribute this exceptional hydrogen production-which far exceeds that of previously reported low-temperature APRM catalysts-to the outstanding ability of α-MoC to induce water dissociation, and to the fact that platinum and α-MoC act in synergy to activate methanol and then to reform it.

18.
BMC Musculoskelet Disord ; 24(1): 683, 2023 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-37644473

RESUMO

BACKGROUND: Alignment is indispensable for the foot and ankle function, especially in the hindfoot alignment. In the preoperative planning of patients with varus or valgus deformity, the precise measurement of the hindfoot alignment is important. A new method of photographing and measuring hindfoot alignment based on X-ray was proposed in this study, and it was applied in the assessment of flatfoot. METHODS: This study included 28 patients (40 feet) with flatfeet and 20 volunteers (40 feet) from January to December 2018. The hindfoot alignment shooting stand independently designed by our department was used to take hindfoot alignment X-rays at 10 degree, 15 degree, 20 degree, 25 degree, and 30 degree. We measured the modified tibio-hindfoot angle (THA) at the standard hindfoot aligment position (shooting at 20 degree) and evaluated consistency with the van Dijk method and the modified van Dijk method. In addition, we observed the visibility of the tibiotalar joint space from all imaging data at five projection angles and evaluated the consistency of the modified THA method at different projection angles. The angle of hindfoot valgus of flatfoot patients was measured using the modified THA method. RESULTS: The mean THA in the standard hindfoot aligment view in normal people was significantly different among the three evaluation methods (P < .001). The results from the modified THA method were significantly larger than those from the Van Dijk method (P < .001) and modified Van Dijk method (P < .001). There was no significant difference between the results of the modified THA method and the weightbearing CT (P = .605), and the intra- and intergroup consistency were the highest in the modified THA group. The tibiotalar space in the normal group was visible in all cases at 10 degree, 15 degree, and 20 degree; visible in some cases at 25 degree; and not visible in all cases at 30 degree. In the flatfoot group, the tibiotalar space was visible in all cases at 10 degree, visible in some cases at 15 degree and 20 degree, and not visible in all cases at 25 degree and 30 degree. In the normal group, the modified THA was 4.84 ± 1.81 degree at 10 degree, 4.96 ± 1.77 degree at 15 degree, and 4.94 ± 2.04 degree at 20 degree. No significant differences were found among the three groups (P = .616). In the flatfoot group, the modified THA of 18 feet, which was visible at 10 degree, 15 degree and 20 degree, was 13.58 ± 3.57 degree at 10 degree, 13.62 ± 3.83 degree at 15 degree and 13.38 ± 4.06 degree at 20 degree. There were no significant differences among the three groups (P = .425). CONCLUSIONS: The modified THA evaluation method is simple to use and has high inter- and intragroup consistency. It can be used to evaluate hindfoot alignment. For patients with flatfeet, the 10 degree position view and modified THA measurement can be used to evaluate hindfoot valgus.


Assuntos
Pé Chato , Humanos , Pé Chato/diagnóstico por imagem , , Radiografia , Extremidade Inferior , Articulação do Tornozelo
19.
Phytochem Anal ; 34(5): 560-570, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37202874

RESUMO

INTRODUCTION: Lanqin Oral Liquid (LQL) is a traditional Chinese medicine preparation (TCMP) containing five herbal medicines and has been commonly used for the treatment of pharyngitis and hand-foot-and-mouth disease in clinic. The material basis of LQL has been reported in our previous study, but the contents of the major components and the features of saccharide in LQL are still unclear. OBJECTIVES: This study aimed to establish accurate and rapid methods for the quantification of the major components and profiling of saccharide in LQL. The quantitative results combined with similarity evaluation were applied to improve the quality control of LQL. METHODOLOGY: An ultra-high performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-QQQ-MS) method was utilised to determine 44 major components. Cosine similarity was used to evaluate the similarities among 20 batches of LQL based on the quantitative results of 44 major components. The physicochemical properties, structure, composition, and contents of saccharide in LQL were detected by a combination of chemical and instrumental analysis. RESULTS: A total of 44 compounds, including flavonoids, iridoid glycosides, alkaloids, and nucleosides, were accurately determined. The 20 batches of LQL were remarkably similar (> 0.95). In addition, d-glucose, galactose, d-glucuronic acid, arabinose, and d-mannose were detected in saccharide of LQL. The contents of saccharide in LQL were 13.52-21.09 mg/ml. CONCLUSIONS: The established methods can be applied for the comprehensive quality control of LQL, including characterisation of saccharide and quantification of representative components. Our study will provide a robust chemical foundation for disclosing the quality markers of its therapeutic effect.


Assuntos
Medicamentos de Ervas Chinesas , Medicamentos de Ervas Chinesas/química , Medicina Tradicional Chinesa , Espectrometria de Massas em Tandem/métodos , Flavonoides/análise , Controle de Qualidade , Cromatografia Líquida de Alta Pressão/métodos
20.
Angew Chem Int Ed Engl ; 62(13): e202219299, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36734471

RESUMO

The activation of water molecules in thermal catalysis typically requires high temperatures, representing an obstacle to catalyst development for the low-temperature water-gas shift reaction (WGSR). Plasmonic photocatalysis allows activation of water at low temperatures through the generation of light-induced hot electrons. Herein, we report a layered double hydroxide-derived copper catalyst (LD-Cu) with outstanding performance for the low-temperature photo-driven WGSR. LD-Cu offered a lower activation energy for WGSR to H2 under UV/Vis irradiation (1.4 W cm-2 ) compared to under dark conditions. Detailed experimental studies revealed that highly dispersed Cu nanoparticles created an abundance of hot electrons during light absorption, which promoted *H2 O dissociation and *H combination via a carboxyl pathway, leading to the efficient production of H2 . Results demonstrate the benefits of exploiting plasmonic phenomena in the development of photo-driven low-temperature WGSR catalysts.

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