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Triggering the lattice oxygen oxidation mechanism is crucial for improving oxygen evolution reaction (OER) performance, because it could bypass the scaling relation limitation associated with the conventional adsorbate evolution mechanism through the direct formation of oxygen-oxygen bond. High-valence transition metal sites are favorable for activating the lattice oxygen, but the deep oxidation of pre-catalysts suffers from a high thermodynamic barrier. Here, taking advantage of the Jahn-Teller (J-T) distortion induced structural instability, we incorporate high-spin Mn3+ ( t 2 g 3 e g 1 ${{t}_{2g}^{3}{e}_{g}^{1}}$ ) dopant into Co4N. Mn dopants enable a surface structural transformation from Co4N to CoOOH, and finally to CoO2, as observed by various in situ spectroscopic investigations. Furthermore, the reconstructed surface on Mn-doped Co4N triggers the lattice oxygen activation, as evidenced experimentally by pH-dependent OER, tetramethylammonium cation adsorption and online electrochemical mass spectrometry measurements of 18O-labelled catalysts. In general, this work not only offers the introducing J-T effect approach to regulate the structural transition, but also provides an understanding about the influence of the catalyst's electronic configuration on determining the reaction route, which may inspire the design of more efficient catalysts with activated lattice oxygen.
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The development of highly active and low-cost oxygen reduction reaction (ORR) catalysts is crucial for the practical application of hydrogen fuel cells. However, the linear scaling relation (LSR) imposes an inherent Sabatier's limitation for most catalysts including the benchmark Pt with an insurmountable overpotential ceiling, impeding the development of efficient electrocatalysts. To avoid such a limitation, using earth-abundant metal oxides with different crystal phases as model materials, we propose an effective and dynamic reaction pathway through constructing spatially correlated Pt-Mn pair sites, achieving an excellent balance between high activity and low Pt loading. Experimental and theoretical calculations demonstrate that manipulating the intermetallic distance and charge distribution of Pt-Mn pairs can effectively promote O-O bond cleavage at these sites through a bridge configuration, circumventing the formation of *OOH intermediates. Meanwhile, the dynamic adsorption configuration transition from the bridge configuration of O2 to the end-on configuration of *OH improves *OH desorption at the Mn site within such pairs, thereby avoiding Sabatier's limitation. The well-designed Pt-Mn/ß-MnO2 exhibits outstanding ORR activity and stability with a half-wave potential of 0.93 V and barely any activity degradation for 70 h. When applied to the cathode of a H2-O2 anion-exchange membrane fuel cell, this catalyst demonstrates a high peak power density of 287 mW cm-2 and 500 h of stability under a cell voltage of 0.6 V. This work reveals the adaptive bonding interactions of atomic pair sites with multiple reactant/intermediates, offering a new avenue for rational design of highly efficient atomic-level dispersed ORR catalysts beyond the Sabatier optimum.
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Dynamic reconstruction of catalyst active sites is particularly important for metal oxide-catalyzed oxygen evolution reaction (OER). However, the mechanism of how vacancy-induced reconstruction aids OER remains ambiguous. Here, we use Co3O4 with Co or O vacancies to uncover the effects of different defects in the reconstruction process and the active motifs relevant to alkaline OER. Combining in situ characterization and theoretical calculations, we found that cobalt oxides are converted to an amorphous [Co(OH)6] intermediate state, and then the mismatched rates of *OH adsorption and deprotonation lead to irreversible catalyst reconstruction. The stronger *OH adsorption but weaker deprotonation induced by O defects provides the driving force for reconstruction, while Co defects favor dehydrogenation and reduce the reconstruction rate. Importantly, both O and Co defects trigger highly OER-active bridge Co sites in reconstructed catalysts, of which Co defects induce a short Co-Co distance (3.38 Å) under compressive lattice stress and show the best OER activity (η10 of 262 mV), superior to reconstructed oxygen-defected Co3O4-VO (η10 of 300 mV) and defect-free Co3O4 (η10 of 320 mV). This work highlights that engineering defect-dependent reconstruction may provide a rational route for electrocatalyst design in energy-related applications.
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Ambient electrocatalytic nitrogen (N2 ) reduction has gained significant recognition as a potential substitute for producing ammonia (NH3 ). However, N2 adsorption and *NN protonation for N2 activation reaction with the competing hydrogen evolution reaction remain a daunting challenge. Herein, a defect-rich TiO2 nanosheet electrocatalyst with PdCu alloy nanoparticles (PdCu/TiO2-x ) is designed to elucidate the reactivity and selectivity trends of N2 cleavage path for N2 -to-NH3 catalytic conversion. The introduction of oxygen vacancy (OV) not only acts as active sites but also effectively promotes the electron transfer from Pd-Cu sites to high-concentration Ti3+ sites, and thus lends to the N2 activation via electron donation of PdCu. OVs-mediated control effectively lowers the reaction barrier of *N2 H and *H adsorption and facilitates the first hydrogenation process of N2 activation. Consequently, PdCu/TiO2-x catalyst attains a high rate of NH3 evolution, reaching 5.0 mmol gcat. -1 h-1 . This work paves a pathway of defect-engineering metal-supported electrocatalysts for high-efficient ammonia electrosynthesis.
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Nitrates can stimulate the biosynthesis of hydrophilic yellow pigments (HYPs) in Monascus ruber CGMCC 10910. To explore the molecular mechanisms whereby nitrates (NaNO3 and NH4NO3) regulate HYP production, an integrated transcriptomic and proteomic analysis was conducted in this study. Nitrate addition led to an approximately 75% higher HYP production compared with the untreated group, especially compounds Y3 and Y4. Comparative transcriptomic analysis found that mpigsA, H, K, L, and P genes involved in yellow pigment biosynthesis were significantly upregulated. In addition, pigment biosynthesis-related (carbon catabolism, amino acid metabolism, polyketide synthesis, and fatty acid metabolism) genes were upregulated to provide precursors and energy for HYP biosynthesis and cell growth. Secretion-related (cytomembrane ergosterol biosynthetic, and transport) pathways were also noticeably regulated to accelerate transmembrane transport of HYPs. Meanwhile, proteomic analysis showed that nitrates improved the protein expression of hybrid polyketide synthase-nonribosomal peptide synthetase, oxidoreductase, glucoamylase, endo-1,4-beta-xylanase, O-acetylhomoserine, and isocitrate lyase to enhance HYP production. These findings demonstrated the regulatory mechanism of nitrates for enhancing HYP production in Monascus. KEY POINTS: ⢠Nitrates stimulated the biosynthesis of Monascus hydrophilic yellow pigments (HYPs) ⢠Nitrates affected transcriptional level of pigment biosynthesis- and transport genes ⢠Increased expression of hybrid PKS-NRPS and transporters promoted production of HYPs.
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Monascus , Nitratos , Fermentação , Nitratos/metabolismo , Pigmentos Biológicos , Monascus/metabolismo , Proteômica , TranscriptomaRESUMO
OBJECTIVES: To study the impact of a balloon occlusion (BO) technique in stented elephant trunk implantation in Sun's procedure for acute Stanford type A aortic dissection (AAAD) on important postoperative organ complications and patient rehabilitation. METHODS: Eighty-five patients with AAAD who underwent Sun's procedure from January 2019 to January 2020 were selected. Cases were divided into two groups based on whether the aortic BO technique was used in stented elephant trunk implantation: the BO group and the nonballoon occlusion (NBO) group. The collected data included the patients' clinical characteristics, operative data, postoperative complications and recovery. We applied statistical software to study the impact of a BO technique in stented elephant trunk implantation in Sun's procedure. RESULTS: A total of 85 patients with AAAD underwent Sun's procedure. A total of 29 used BO technique, 56 did not use. The circulatory arrest time in the BO group was controlled within 8.07 ± 2.33 min, and the nasopharyngeal temperature dropped to 28°C. Overall postoperative complications were less frequent in BO group than NBO group (52% vs. 75%; p = .030). Using BO technique, we reduced the 24-h drainage volume, and lowered the occurrence of hypoxemia (48%), liver dysfunction (10%), and median tracheal intubation time was 37 h (range: 12.5-106 h), median intensive care unit (ICU) time was 65 h (range: 17-207 h). CONCLUSIONS: During total aortic arch replacement and stented elephant trunk surgery for AAAD, we used the aortic BO technique, which avoids deeper hypothermia and effectively shortens circulatory arrest times. This approach is helpful for reducing the incidence of postoperative complications and shortening the intensive care unit time. This method also reduces the patient's medical burden and facilitates faster recovery.
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Aneurisma da Aorta Torácica , Doenças da Aorta , Dissecção Aórtica , Oclusão com Balão , Implante de Prótese Vascular , Dissecção Aórtica/cirurgia , Aorta Torácica/cirurgia , Aneurisma da Aorta Torácica/cirurgia , Doenças da Aorta/cirurgia , Implante de Prótese Vascular/métodos , Humanos , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle , Estudos Retrospectivos , Stents/efeitos adversos , Resultado do TratamentoRESUMO
Natural water-soluble Monascus pigments (WSMPs) have been in increasing demand but have not been able to achieve industrial production due to the low production rate. This study aimed to improve the biosynthesis and secretion of extracellular yellow pigments (EYPs) through submerged fermentation with Monascus ruber CGMCC 10,910 supplemented with sodium starch octenyl succinate (OSA-SNa). The results demonstrated that the yield was 69.68% and 48.89% higher than that without OSA-SNa in conventional fermentation (CF) and extractive fermentation (EF), respectively. The mainly increased EYP components were Y3 and Y4 in CF, but they were mainly Y1 and Y2 as well as secreted intracellular pigments, including Y5, Y6, O1, and O2, in EF. Scanning electron microscopy analysis revealed that the mycelium presented an uneven surface profile with obvious wrinkles and small fragments with OSA-SNa. It was found that a higher unsaturated/saturated fatty acids ratio in the cell membrane resulted in increased permeability and facilitated the export of intracellular yellow pigments into the broth with OSA-SNa treatment. In addition, a higher NAD+/NADH ratio and glucose-6-phosphate dehydrogenase activity provided a reducing condition for yellow pigment biosynthesis. Gene expression analysis showed that the expression levels of the key genes for yellow pigment biosynthesis were significantly upregulated by OSA-SNa. This study provides an effective strategy to promote the production of WSMPs by microparticle-enhanced cultivation using OSA-SNa. KEY POINTS: ⢠OSA-SNa addition facilitated the production of Monascus yellow pigments. ⢠Mycelial morphology and membrane permeability were affected by OSA-SNa. ⢠The key gene expression of yellow pigments was upregulated.
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Monascus , Fermentação , Monascus/metabolismo , Pigmentos Biológicos/metabolismo , Sódio , Amido , Succinatos , ÁguaRESUMO
Monascus pigments (MPs) are widely used natural colorants in Asian countries. The problems of low extracellular red pigment (ERP) and high citrinin remain to be solved in Monascus pigment production. The effect of lanthanum(III) ion (LaCl3) on Monascus purpureus fermentation was investigated in this study. The yields of ERP and biomass respectively reached maxima of 124.10 U/mL and 33.10 g/L by adding 0.4 g/L La3+ on the second day in the total 8-day fermentation; simultaneously, citrinin was decreased by 59.93% and 38.14% in the extracellular and intracellular fractions, respectively. Reactive oxygen species (ROS) levels were obviously improved by La3+ treatment, while the activities of catalase (CAT) and superoxide dismutase (SOD) were increased compared with the control. The ratio of unsaturated/saturated fatty acids in mycelia was increased from 2.94 to 3.49, indicating that the permeability and fluidity of the cell membrane were enhanced under La3+ treatment. Gene expression analysis showed that the relative expression levels of Monascus pigment synthesis genes (pksPT, mppB, mppD, MpFasB2, and MpPKS5) were significantly upregulated by La3+ treatment, and in contrast, the relative expression levels of citrinin synthesis genes (ctnA, pksCT and mppC) were markedly downregulated. This work confirmed that LaCl3 possesses the potential to induce red pigment biosynthesis and inhibit citrinin production in M. purpureus fermentation. KEY POINTS: ⢠La3+ induced red pigment and inhibited citrinin production in Monascus fermentation. ⢠La3+ regulated genes expression up for Monascus pigment and down for citrinin. ⢠La3+ increased the UFAs in cell membrane to enhance the permeability and fluidity.
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Citrinina , Monascus , Ásia , Fermentação , Lantânio , Monascus/metabolismo , Pigmentos Biológicos/metabolismoRESUMO
Electricity-driven water splitting can facilitate the storage of electrical energy in the form of hydrogen gas. As a half-reaction of electricity-driven water splitting, the oxygen evolution reaction (OER) is the major bottleneck due to the sluggish kinetics of this four-electron transfer reaction. Developing low-cost and robust OER catalysts is critical to solving this efficiency problem in water splitting. The catalyst design has to be built based on the fundamental understanding of the OER mechanism and the origin of the reaction overpotential. In this article, we summarize the recent progress in understanding OER mechanisms, which include the conventional adsorbate evolution mechanism (AEM) and lattice-oxygen-mediated mechanism (LOM) from both theoretical and experimental aspects. We start with the discussion on the AEM and its linked scaling relations among various reaction intermediates. The strategies to reduce overpotential based on the AEM and its derived descriptors are then introduced. To further reduce the OER overpotential, it is necessary to break the scaling relation of HOO* and HO* intermediates in conventional AEM to go beyond the activity limitation of the volcano relationship. Strategies such as stabilization of HOO*, proton acceptor functionality, and switching the OER pathway to LOM are discussed. The remaining questions on the OER and related perspectives are also presented at the end.
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Colorectal cancer (CRC) is one of the most common malignant tumors and is associated with a high mortality rate due to the lack of specific biomarkers available for early diagnosis, targeted therapies, and prognostic surveillance. In the present study, we investigated the function of Numb and its underlying mechanism in CRC. Immunohistochemical staining and clinicopathological analysis were used to assess the expression of Numb and its clinical significance in patients with CRC. Quantitative real-time polymerase chain reaction, cell proliferation, Western blot, wound healing, Transwell, and TOP/FOP flash reporter assays were used to investigate the function of Numb and its underlying mechanism in CRC. Numb expression was downregulated and negatively correlated with the depth of invasion, tumor size, metastasis, TNM stage, and epithelial-to-mesenchymal transition (EMT) markers in CRC specimens. Numb negatively regulates the EMT, proliferation, invasion, migration, and the Wnt signaling pathway in vitro, as well as tumor growth and metastasis in vivo. Furthermore, activation of the Wnt signaling pathway by Wnt-3A negated the effect of Numb overexpression, whereas inhibition of the Wnt signaling pathway by IWR-1 impaired the effect of the Numb knockdown on the EMT. We concluded that Numb downregulation is a common event in patients with CRC and is closely correlated with cancer progression and a poor prognosis. Numb functions as a tumor suppressor in CRC, and its tumor suppressor function is mediated by negative regulation of the EMT through the Wnt signaling pathway.NEW & NOTEWORTHY We investigate the function of Numb and its underlying mechanism in colorectal cancer through quantitative real-time polymerase chain reaction, cell proliferation, Western blot, wound healing, Transwell, and TOP/FOP flash reporter assays. We conclude that Numb can negatively regulate the epithelial-to-mesenchymal transition through the Wnt signaling pathway to inhibit the development of colorectal cancer.
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Neoplasias Colorretais/metabolismo , Transição Epitelial-Mesenquimal , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Via de Sinalização Wnt , Proteína Wnt3A/metabolismo , Animais , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Proteínas de Membrana/genética , Camundongos Endogâmicos NOD , Camundongos SCID , Pessoa de Meia-Idade , Metástase Neoplásica , Proteínas do Tecido Nervoso/genética , Carga Tumoral , Proteína Wnt3A/genéticaRESUMO
Mycelial adhesion affects cell growth and the production of water-soluble extracellular yellow pigment (EYP) in submerged fermentation with Monascus ruber CGMCC 10910. Two nitrates, NaNO3 and KNO3, were used as nitrogen sources for mitigating mycelial adhesion and improving the production of EYP in this study. The results showed that the adhesion of mycelia in the fermentation broth significantly decreased by adding 5 g/L NaNO3, which prevented mycelia from attaching to the inner wall of the Erlenmeyer flask. It was suggested that NaNO3 reduced the total amount of extracellular polysaccharides, increased extracellular proteins, and decreased the viscosity of the fermentation broth. Scanning electron microscopy (SEM) analysis revealed that the mycelial morphology was shorter and more dispersed and vigorous under NaNO3 conditions than under the control conditions. The biomass increased by 49.2% and 45.4% with 5 g/L NaNO3 and 6 g/L KNO3 treatment, respectively, compared with that of the control, and the maximum production of EYP was 267.1 and 241.8 AU350, which increased by 70.0% and 53.9% compared with that of the control, respectively. Simultaneously, the ratios of intracellular yellow pigment to orange pigment increased significantly with 5 g/L of NaNO3 addition (p < 0.05). Genetic analysis found that the expression levels of the key genes for Monascus pigment biosynthesis were significantly upregulated by NaNO3 addition (p < 0.05 or p < 0.01). This study provides an effective strategy for the production of water-soluble Monascus yellow pigments.Key Points⢠Nitrate addition decreased mycelial adhesion and improved cell growth in Monascus pigment fermentation.⢠The biosynthesis genes of water-soluble extracellular yellow pigment (EYP) were upregulated by nitrate addition.⢠The mycelial morphology was significantly influenced to enhance EYP biosynthesis with nitrate addition.
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Monascus , Fermentação , Monascus/metabolismo , Nitratos , Pigmentação , Pigmentos Biológicos/metabolismoRESUMO
Trametes versicolor extracts have been shown to have health-promoting benefits in hypercholesterolemia, obesity, hepatic steatosis, and cardiovascular disease. However, hypolipidemic or the anti-hyperlipidemic effects of polysaccharide extracts of T. versicolor (PTVs) are not yet clear. In present work, the structural characterization of intracellular (IPTV) and the extracellular polysaccharide extracts of T. versicolor (EPTV) were partially clarified, and their effects on serum lipid metabolism and regulation of lipid-regulating enzymes in high-fat diet-induced hyperlipidemic mice were also investigated. Results indicated that IPTV and EPTV are α-pyran polysaccharide with an average molecular weight of 127 and 68.4 kDa, respectively, and were mainly composed of mannose, glucose and galactose. In vivo study, EPTV treatment (200 mg/kg/d) significantly decreased serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), and atherosclerosis index (AI) of hyperlipidemic mice by 20.97%, 57.85%, 27.72%, and 20.35%, respectively (P < 0.01), while IPTV treatment (100 mg/kg/d) showed a significant (P < 0.01) decrease in serum TC (17.05%), TG (43.80%), LDL-C (25.61%) levels, and AI value (13.32%). A significant increase in serum lipoprotein lipase (LPL) activity and decrease in protein expression of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) were observed following EPTV administration, while IPTV remarkably promoted LPL activity. These results suggest that IPTV and EPTV which improve serum lipid profiles in high-fat diet-induced hyperlipidemic mice via mechanisms regulated by serum LPL and hepatic HMGR have potential for further development as novel therapeutic dietary supplements for the prevention and treatment of hyperlipidemia.
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Lipídeos , Trametes , Animais , Dieta Hiperlipídica/efeitos adversos , Metabolismo dos Lipídeos , Fígado/metabolismo , Camundongos , Extratos Vegetais/metabolismo , Extratos Vegetais/farmacologia , Polyporaceae , Polissacarídeos/metabolismoRESUMO
Metal complexes have been widely investigated as promising electrocatalysts for CO2 reduction. Most of the current research efforts focus mainly on ligands based on pyrrole subunits, and the reported activities are still far from satisfactory. A novel planar and conjugated N4 -macrocyclic cobalt complex (Co(II)CPY) derived from phenanthroline subunits is prepared herein, and it delivers high activity for heterogeneous CO2 electrocatalysis to CO in aqueous media, and outperforms most of the metal complexes reported so far. At a molar loading of 5.93×10-8 â mol cm-2 , it exhibits a Faradaic efficiency of 96 % and a turnover frequency of 9.59â s-1 towards CO at -0.70â V vs. RHE. The unraveling of electronic structural features suggests that a synergistic effect between the ligand and cobalt in Co(II)CPY plays a critical role in boosting its activity. As a result, the free energy difference for the formation of *COOH is lower than that with cobalt porphyrin, thus leading to enhanced CO production.
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Electrochemical CO2 reduction relies on the availability of highly efficient and selective catalysts. Herein, we report a general strategy to boost the activity of metal-organic frameworks (MOFs) towards CO2 reduction via ligand doping. A strong electron-donating molecule of 1,10-phenanthroline was doped into Zn-based MOFs of zeolitic imidazolate framework-8 (ZIF-8) as CO2 reduction electrocatalyst. Experimental and theoretical evidences reveal that the electron-donating nature of phenanthroline enables a charge transfer, which induces adjacent active sites at the sp2 C atoms in the imidazole ligand possessing more electrons, and facilitates the generation of *COOH, hence leading to improved activity and Faradaic efficiency towards CO production.
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A cost-effective and efficient electrocatalyst for the oxygen evolution reaction during the electrolysis of water is highly desired. In an effort to develop an economical material for replacing precious-metal-based catalysts, a novel and self-standing amorphous ultrathin nanosheet (NS) of bimetallic iron-nickel boride (Fe-Ni-B NSs) on Ni foam is presented, which displays a better oxygen-evolving activity compared to the precious-metal catalyst RuO2 . In 1.0 m KOH electrolyte solution, it requires an overpotential of only 237â mV to reach a current density of 10â mA cm-2 with a small Tafel slope of 38â mV dec-1 and shows prominent long-term electrochemical stability. A synergistic effect between highly abundant catalytically active sites on the 3D porous substrate improved the electron transport arising from the presence of highly negative boron, and the high conductivity of the substrate results in an outstanding electrocatalytic activity. The advanced catalytic activity, facile electrode fabrication, and low costs make it a potential oxygen-evolving material, which may be extended to other energy-conversion and storage technologies.
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BACKGROUND: Laparoscopy has been proposed for the management of recurrent hepatolithiasis, but no comparative study of its relative efficacy versus laparotomy has been performed, and the patient selection criteria for laparoscopy are not clear. This study aimed to investigate the therapeutic effect of laparoscopy versus laparotomy for repeated hepatolithiasis and to highlight how to select patients best suited for laparoscopy. METHODS: We performed a cohort study of 94 patients who underwent laparotomy or laparoscopy for recurrent hepatolithiasis between January 2010 and May 2014. The clinical data of 53 patients who underwent open biliary exploration (laparotomy group) and 41 patients who underwent laparoscopic biliary exploration (laparoscopy group) for recurrent hepatolithiasis were retrospectively analyzed and compared. RESULTS: Intestinal adhesions to the porta hepatis occurred in 62 (66%) patients. There was no difference in operating time between the two groups. In comparing the laparoscopic group versus the laparotomy group, the intraoperative blood loss was less (P = .001), the incidence of postoperative ascites (9.8 vs. 30.2%, P = .016) and/or pleural effusion (7.3 vs. 28.3%, P = .010) was lower, and the stone clearance rates were comparable. Wound morbidity appeared peculiarly in 15 (28.3%) patients among the laparotomy group. The postoperative hospital stay in the laparoscopy group was shorter than that in the laparotomy group (P = .000). CONCLUSION: Laparoscopy is a safe and effective treatment for recurrent hepatolithiasis patients who are scheduled for bile duct exploration.
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Procedimentos Cirúrgicos do Sistema Biliar/métodos , Cálculos/cirurgia , Colelitíase/cirurgia , Laparoscopia , Laparotomia , Hepatopatias/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Ascite/epidemiologia , Perda Sanguínea Cirúrgica , Estudos de Coortes , Feminino , Hepatectomia , Humanos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Seleção de Pacientes , Derrame Pleural/epidemiologia , Complicações Pós-Operatórias/epidemiologia , Recidiva , Reoperação , Estudos Retrospectivos , Resultado do TratamentoRESUMO
The development of highly active, universal, and stable inexpensive electrocatalysts/cocatalysts for hydrogen evolution reaction (HER) by morphology and structure modulations remains a great challenge. Herein, a simple self-template strategy was developed to synthesize hollow Co-based bimetallic sulfide (MxCo3-xS4, M = Zn, Ni, and Cu) polyhedra with superior HER activity and stability. Homogenous bimetallic metal-organic frameworks are transformed to hollow bimetallic sulfides by solvothermal sulfidation and thermal annealing. Electrochemical measurements and density functional theory computations show that the combination of hollow structure and homoincorporation of a second metal significantly enhances the HER activity of Co3S4. Specifically, the homogeneous doping in Co3S4 lattice optimizes the Gibbs free energy for H* adsorption and improves the electrical conductivity. Impressively, hollow Zn0.30Co2.70S4 exhibits electrocatalytic HER activity better than most of the reported nobel-metal-free electrocatalysts over a wide pH range, with overpotentials of 80, 90, and 85 mV at 10 mA cm(-2) and 129, 144, and 136 mV at 100 mA cm(-2) in 0.5 M H2SO4, 0.1 M phosphate buffer, and 1 M KOH, respectively. It also exhibits photocatalytic HER activity comparable to that of Pt cocatalyst when working with organic photosensitizer (Eosin Y) or semiconductors (TiO2 and C3N4). Furthermore, this catalyst shows excellent stability in the electrochemical and photocatalytic reactions. The strategy developed here, i.e., homogeneous doping and self-templated hollow structure, provides a way to synthesize transition metal sulfides for catalysis and energy conversion.
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Inflammatory bowel disease (IBD) is a serious public health issue because of its chronic and incurable nature. Common IBD drugs have limited efficacy and produce adverse effects, leading to an urgent need to develop new drugs and drug delivery systems. Curcumin (Cur) is a natural and nontoxic drug that is increasingly used in the treatment of IBD owing to its anti-inflammatory and antioxidant effects. Metal-polyphenol networks constructed from metal ions and polyphenols exhibit biological functionality while acting as an adhesive nanomaterial to encapsulate nano-Cur, thereby improving its solubility and drug release behavior. In this study, we prepared a Cur@Fe&TA nanodrug delivery system by constructing an Fe3+/tannic acid (TA) metal-polyphenol network with encapsulated Cur. The Cur@Fe&TA nanodrug exhibited good stability, drug release behavior, and biocompatibility. Based on the anti-inflammatory and antioxidant effects of Cur@Fe&TA, the gastrointestinal cytopathology in an IBD mouse model was effectively improved. The proposed Cur@Fe&TA nanomedicine delivery system has promising application and research value for the treatment of IBD by regulating levels of antioxidants and inflammatory cytokines.
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Dual-atom site catalysts (DASCs) have sparked considerable interest in heterogeneous photocatalysis as they possess the advantages of excellent photoelectronic activity, photostability, and high carrier separation efficiency and mobility. The DASCs involved in these important photocatalytic processes, especially in the photocatalytic hydrogen evolution reaction (HER), CO2 reduction reaction (CO2RR), N2/nitrate reduction, etc., have been extensively investigated in the past few years. In this review, we highlight the recent progress in DASCs that provides fundamental insights into the photocatalytic conversion of small molecules. The controllable preparation and characterization methods of various DASCs are discussed. Subsequently, the reaction mechanisms of the formation of several important molecules (hydrogen, hydrocarbons and ammonia) on DASCs are introduced in detail, in order to probe the relationship between DASCs's structure and photocatalytic activity. Finally, some challenges and outlooks of DASCs in the photocatalytic conversion of small molecules are summarized and prospected. We hope that this review can provide guidance for in-depth understanding and aid in the design of efficient DASCs for photocatalysis.
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Lignin is the main component of lignocellulose and the largest source of aromatic substances on the earth. Biofuel and bio-chemicals derived from lignin can reduce the use of petroleum products. Current advances in lignin catalysis conversion have facilitated many of progress, but understanding the principles of catalyst design is critical to moving the field forward. In this review, the factors affecting the catalysts (including the type of active metal, metal particle size, acidity, pore size, the nature of the oxide supports, and the synergistic effect of the metals) are systematically reviewed based on the three most commonly used supports (carbon, oxides, and zeolites) in lignin hydrogenolysis. The catalytic performance (selectivity and yield of products) is evaluated, and the emerging catalytic mechanisms are introduced to better understand the catalyst design guidelines. Finally, based on the progress of existing studies, future directions for catalyst design in the field of lignin depolymerization are proposed.