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1.
J Am Chem Soc ; 146(14): 10084-10092, 2024 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-38530325

RESUMEN

Glycine is a nonessential amino acid that plays a vital role in various biological activities. However, the conventional synthesis of glycine requires sophisticated procedures or toxic feedstocks. Herein, we report an electrochemical pathway for glycine synthesis via the reductive coupling of oxalic acid and nitrate or nitrogen oxides over atomically dispersed Fe-N-C catalysts. A glycine selectivity of 70.7% is achieved over Fe-N-C-700 at -1.0 V versus RHE. Synergy between the FeN3C structure and pyrrolic nitrogen in Fe-N-C-700 facilitates the reduction of oxalic acid to glyoxylic acid, which is crucial for producing glyoxylic acid oxime and glycine, and the FeN3C structure could reduce the energy barrier of *HOOCCH2NH2 intermediate formation thus accelerating the glyoxylic acid oxime conversion to glycine. This new synthesis approach for value-added chemicals using simple carbon and nitrogen sources could provide sustainable routes for organonitrogen compound production.

2.
Blood Cells Mol Dis ; 107: 102858, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38796983

RESUMEN

Immune thrombocytopenia (ITP) is an autoimmune disease caused by the loss of immune tolerance to platelet autoantigens, resulting in reduced platelet production and increased platelet destruction. Impaired megakaryocyte differentiation and maturation is a key factor in the pathogenesis and treatment of ITP. Sarcandra glabra, a plant of the Chloranthaceae family, is commonly used in clinical practice to treat ITP, and daucosterol (Dau) is one of its active ingredients. However, whether Dau can treat ITP and the key mechanism of its effect are still unclear. In this study, we found that Dau could effectively promote the differentiation and maturation of megakaryocytes and the formation of polyploidy in the megakaryocyte differentiation disorder model constructed by co-culturing Dami and HS-5 cells. In vivo experiments showed that Dau could not only increase the number of polyploidized megakaryocytes in the ITP rat model, but also promote the recovery of platelet count. In addition, through network pharmacology analysis, we speculated that the JAK2-STAT3 signaling pathway might be involved in the process of Dau promoting megakaryocyte differentiation. Western blot results showed that Dau inhibited the expression of P-JAK2 and P-STAT3. In summary, these results provide a basis for further studying the pharmacological mechanism of Dau in treating ITP.


Asunto(s)
Diferenciación Celular , Janus Quinasa 2 , Megacariocitos , Púrpura Trombocitopénica Idiopática , Factor de Transcripción STAT3 , Transducción de Señal , Animales , Humanos , Masculino , Ratas , Diferenciación Celular/efectos de los fármacos , Modelos Animales de Enfermedad , Janus Quinasa 2/metabolismo , Megacariocitos/metabolismo , Megacariocitos/efectos de los fármacos , Megacariocitos/citología , Púrpura Trombocitopénica Idiopática/metabolismo , Púrpura Trombocitopénica Idiopática/tratamiento farmacológico , Púrpura Trombocitopénica Idiopática/patología , Transducción de Señal/efectos de los fármacos , Sitoesteroles/farmacología , Factor de Transcripción STAT3/metabolismo
3.
Acc Chem Res ; 56(24): 3558-3571, 2023 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-38029298

RESUMEN

ConspectusIn recent years, significant efforts have been directed toward achieving efficient and mild lignocellulosic biomass conversion into valuable chemicals and fuels, aiming to address energy and environmental concerns and realize the goal of carbon neutrality. Lignin is one of the three primary building blocks of lignocellulose and the only aromatic renewable feedstock. However, the complex and diverse nature of lignin feedstocks, characterized by their three-dimensional, highly branched polymeric structure and intricate C-O/C-C chemical bonds, results in substantial challenges. To tackle these challenges, we carried out extensive research on selectively activating and transforming chemical bonds in lignin for chemical synthesis. In this Account, we discuss our recent progress in catalytic lignin conversion.Our work is focused on two main objectives: (i) achieving precise and selective transformation of C-O/C-C bonds in lignin (and its model compounds) and (ii) fully utilizing the aromatic nuclei and side chains present in lignin to produce valuable chemicals. Lignin consists of interconnected phenylpropanoid subunits linked by interlaced C-C/C-O bonds. To unlock the full potential of lignin, we propose the concept of "the full utilization of lignin", which encompasses both the aromatic nuclei and the side chains (e.g., methoxyl and polyhydroxypropyl groups).For the conversion of aromatic nuclei, selective activation of C-O and/or C-C bonds is crucial in synthesizing targeted aromatic products. We begin with model compounds (such as anisole, phenol, guaiacol, etc.) and then transition to protolignin feedstocks. Various reaction routes are developed, including self-supported hydrogenolysis, direct Caryl-Csp3 cleavage, coupled Caryl-Csp3 cleavage and Caryl-O hydrogenolysis, and tandem selective hydrogenation and hydrolysis processes. These tailored pathways enable high-yield and sustainable production of a wide range of aromatic (and derived) products, including arenes (benzene, toluene, alkylbenzenes), phenols, ketones, and acids.In terms of side chain utilization, we have developed innovative strategies such as selective methyl transfer, coupling depolymerization-methyl shift, selective acetyl utilization, and new activation methods such as amine-assisted prefunctionalization. These strategies enable the direct synthesis of methyl-/alkyl-derived products, such as acetic acid, 4-ethyltoluene, dimethylethylamine, and amides. Additionally, aromatic residues can be transformed into chemicals or functionalized ingredients that can serve as catalysts or functional biopolymer materials. These findings highlight promising opportunities for harnessing both the aromatic nuclei and side chains of lignin in a creative manner, thereby improving the overall atom economy of lignin upgrading.Through innovative catalyst engineering and reaction route strategies, our work achieves the sustainable and efficient production of various valuable chemicals from lignin. By integrating side chains and aromatic rings, we have successfully synthesized methyl-/alkyl-derived and aromatic-derived products with high yields. The full utilization of lignin not only minimizes waste but also opens up new possibilities for generating chemical products from lignin. These novel approaches unlock the untapped potential of lignin, expand the boundaries of lignin upgrading, and enhance the efficiency and economic viability of lignin biorefining.

4.
J Vasc Surg ; 79(4): 763-775.e2, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38042512

RESUMEN

OBJECTIVE: The abdominal aortic aneurysm (AAA) is associated with alterations in the composition of the gut microbiota; however, the precise causal relationship remains unclear. Elucidating this complex interplay could provide new insights into the pathogenesis of AAA. METHODS: A bidirectional two-sample Mendelian randomization analysis was conducted using genome-wide association study summary data on the gut microbiota (n = 18,340) and AAA (n = 353,087). A total of 196 gut microbial taxa across taxonomic levels were examined for their potential causal effects on AAA risk. Conversely, the effect of AAA on these microbial taxa was also analyzed. RESULTS: Nine microbial taxa were identified as having a causal influence on AAA risk. Specifically, increased risk were associated with genus Bilophila (odds ratio [OR], 1.359; P = .0119), genus Catenibacterium (OR, 1.348; P = .0058), genus family XIII AD3011 group (OR, 1.507; P = .004), genus Oxalobacter (OR, 1.157; P = .0449), and genus Prevotella 7 (OR, 1.194; P = .0306), whereas decreased risks were linked to class Lentisphaeria (OR, 0.829; P = .0361), order Victivallales (OR, 0.829; P = .0361), family Victivallaceae (OR, 0.814; P = .0057), and genus Anaerotruncus (OR, 0.773; P = .0497). Furthermore, AAA was found to influence the abundance of 14 microbial taxa across various taxonomic levels. Notably, bidirectional associations were observed with the class Lentisphaeria and the order Victivallales. CONCLUSIONS: This study provides novel evidence for a reciprocal causal relationship between gut microbiota and AAA risk, thereby offering new insights into the pathogenesis of AAA. These findings also suggest promising avenues for microbiome-based therapeutic interventions.


Asunto(s)
Aneurisma de la Aorta Abdominal , Microbioma Gastrointestinal , Humanos , Estudio de Asociación del Genoma Completo , Análisis de la Aleatorización Mendeliana , Aneurisma de la Aorta Abdominal/genética , Oportunidad Relativa
5.
BMC Infect Dis ; 24(1): 282, 2024 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-38438863

RESUMEN

BACKGROUND: The performance of the sepsis-induced coagulopathy (SIC) and sequential organ failure assessment (SOFA) scores in predicting the prognoses of patients with sepsis has been validated. This study aimed to investigate the time course of SIC and SOFA scores and their association with outcomes in patients with sepsis. METHODS: This prospective study enrolled 209 patients with sepsis admitted to the emergency department. The SIC and SOFA scores of the patients were assessed on days 1, 2, and 4. Patients were categorized into survivor or non-survivor groups based on their 28-day survival. We conducted a generalized estimating equation analysis to evaluate the time course of SIC and SOFA scores and the corresponding differences between the two groups. The predictive value of SIC and SOFA scores at different time points for sepsis prognosis was evaluated. RESULTS: In the non-survivor group, SIC and SOFA scores gradually increased during the first 4 days (P < 0.05). In the survivor group, the SIC and SOFA scores on day 2 were significantly higher than those on day 1 (P < 0.05); however, they decreased on day 4, dropping below the levels observed on day 1 (P < 0.05). The non-survivors showed higher SIC scores on days 2 (P < 0.05) and 4 (P < 0.001) than the survivors, whereas no significant differences were found between the two groups on day 1 (P > 0.05). The performance of SIC scores on day 4 for predicting mortality was more accurate than that on day 2, with areas under the curve of 0.749 (95% confidence interval [CI]: 0.674-0.823), and 0.601 (95% CI: 0.524-0.679), respectively. The SIC scores demonstrated comparable predictive accuracy for 28-day mortality to the SOFA scores on days 2 and 4. Cox proportional hazards models indicated that SIC on day 4 (hazard ratio [HR] = 3.736; 95% CI: 2.025-6.891) was an independent risk factor for 28-day mortality. CONCLUSIONS: The time course of SIC and SOFA scores differed between surviving and non-surviving patients with sepsis, and persistent high SIC and SOFA scores can predict 28-day mortality.


Asunto(s)
Trastornos de la Coagulación Sanguínea , Sepsis , Humanos , Puntuaciones en la Disfunción de Órganos , Estudios Prospectivos , Sepsis/complicaciones , Trastornos de la Coagulación Sanguínea/etiología , Servicio de Urgencia en Hospital
6.
BMC Public Health ; 24(1): 1184, 2024 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-38678184

RESUMEN

BACKGROUND: With the rapid aging of the domestic population, China has a strong incentive to increase the statutory retirement age. How retirement affects the health of the elderly is crucial to this policymaking. The health consequences of retirement have been debated greatly. This study aims to investigate the effects of retirement on physical and mental health among Chinese elderly people. METHODS: The data we use in this study comes from four waves (2011, 2013, 2015, and 2018) of the Harmonized China Health and Retirement Longitudinal Study (Harmonized CHARLS), a prospective cohort. We use the nonparametric fuzzy regression discontinuity design to estimate the effects of retirement on physical and mental health. We test the robustness of our results with respect to different bandwidths, kernel functions, and polynomial orders. We also explore the heterogeneity across gender and education. RESULTS: Results show that retirement has an insignificant effect on a series of physical and mental health outcomes, with and without adjusting several sociodemographic variables. Heterogeneity exists regarding gender and education. Although stratified analyses indicate that the transition from working to retirement leaves minimal effects on males and females, the effects go in the opposite direction. This finding holds for low-educated and high-educated groups for health outcomes including depression and cognitive function. Most of the results are stable with respect to different bandwidths, kernel functions, and polynomial orders. CONCLUSIONS: Our results suggest that it is possible to delay the statutory retirement age in China as retirement has insignificant effects on physical and mental health. However, further research is needed to assess the long-term effect of retirement on health.


Asunto(s)
Salud Mental , Jubilación , Humanos , Jubilación/estadística & datos numéricos , Jubilación/psicología , China/epidemiología , Masculino , Femenino , Salud Mental/estadística & datos numéricos , Estudios Longitudinales , Anciano , Persona de Mediana Edad , Estudios Prospectivos , Lógica Difusa , Estado de Salud , Análisis de Regresión
7.
Small ; 19(9): e2206175, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36534834

RESUMEN

About 10% efficient antimony selenosulfide (Sb2 (S,Se)3 ) solar cell is realized by using selenourea as a hydrothermal raw material to prepare absorber layers. However, tailoring the bandgap of hydrothermal-based Sb2 (S,Se)3 film to the ideal bandgap (1.3-1.4 eV) using the selenourea for optimal efficiency is still a challenge. Moreover, the expensive selenourea dramatically increases the fabricating cost. Here, a straightforward one-step hydrothermal method is developed to prepare high-quality Sb2 (S,Se)3 films using a novel precursor sodium selenosulfate as the selenium source. By tuning the Se/(Se+S) ratio in the hydrothermal precursor solution, a series of high-quality Sb2 (S,Se)3 films with reduced density of deep defect states and tunable bandgap from 1.31 to 1.71 eV is successfully prepared. Consequently, the best efficiency of 10.05% with a high current density of 26.01 mA cm-2 is achieved in 1.35 eV Sb2 (S,Se)3 solar cells. Compared with the traditional method using selenourea, the production cost for the Sb2 (S,Se)3  devices is reduced by over 80%. In addition, the device exhibits outstanding stability, maintaining more than 93% of the initial power conversion efficiency after 30 days of exposure in the atmosphere without encapsulation. The present work definitely paves a facile and effective way to develop low-cost and high-efficiency chalcogenide-based photovoltaic devices.

8.
BMC Pulm Med ; 23(1): 346, 2023 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-37710218

RESUMEN

BACKGROUND: No multivariable model incorporating erector spinae muscle (ESM) has been developed to predict clinical outcomes in older patients with severe community-acquired pneumonia (SCAP). This study aimed to construct a nomogram based on ESM to predict in-hospital mortality in patients with SCAP. METHODS: Patients aged ≥ 65 years with SCAP were enrolled in this prospective observational study. Least absolute selection and shrinkage operator and multivariable logistic regression analyses were used to identify risk factors for in-hospital mortality. A nomogram prediction model was constructed. The predictive performance was evaluated using the concordance index (C-index), calibration curve, net reclassification improvement (NRI), integrated discrimination improvement (IDI), and decision curve analysis. RESULTS: A total of 490 patients were included, and the in-hospital mortality rate was 36.1%. The nomogram included the following independent risk factors: mean arterial pressure, peripheral capillary oxygen saturation, Glasgow Coma Scale score (GCS), lactate, lactate dehydrogenase, blood urea nitrogen levels, and ESM cross-sectional area. Incorporating ESM into the base model with other risk factors significantly improved the C-index from 0.803 (95% confidence interval [CI], 0.761-0.845) to 0.836 (95% CI, 0.798-0.873), and these improvements were confirmed by category-free NRI and IDI. The ESM-based nomogram demonstrated a high level of discrimination, good calibration, and overall net benefits for predicting in-hospital mortality compared with the combination of confusion, urea, respiratory rate, blood pressure, and age ≥ 65 years (CURB-65), Pneumonia Severity Index (PSI), Acute Physiology and Chronic Health Evaluation II (APACHEII), and Sequential Organ Failure Assessment (SOFA). CONCLUSIONS: The proposed ESM-based nomogram for predicting in-hospital mortality among older patients with SCAP may help physicians to promptly identify patients prone to adverse outcomes. TRIAL REGISTRATION: This study was registered at www.chictr.org.cn (registration number Chi CTR-2300070377).


Asunto(s)
Infecciones Comunitarias Adquiridas , Neumonía , Humanos , Anciano , Mortalidad Hospitalaria , Nomogramas , Ácido Láctico , Músculos
9.
J Am Chem Soc ; 144(4): 1556-1571, 2022 02 02.
Artículo en Inglés | MEDLINE | ID: mdl-35060721

RESUMEN

Cyclohexanone and benzoquinone are important chemicals in chemical and manufacturing industries. The simultaneous production of cyclohexanone and benzoquinone by the reaction of phenol and water is an ideal route for the economical production of the two chemicals. In principle, this can be achieved in an electrochemical reaction system that couples the cathodic reduction of phenol to cyclohexanone and the anodic oxidation of phenol to benzoquinone, which has not been realized. Here, we report the first work on this integration strategy, where nitrogen-doped hierarchically porous carbon (NHPC)-supported NiPt and FeRu designed in this work are very efficient and selective cathode and anode catalysts, affording >99.9% selectivities to both cyclohexanone and benzoquinone. The excellent electrocatalytic performance of the catalysts can be ascribed to the poor absorption capability of the NiPt alloy nanoparticles (NPs) for cyclohexanone and Fe single-atom decorated Ru NPs for benzoquinone, which avoids the excessive reduction and oxidation of the desired products. The reaction pathway is proposed on the basis of control experiments, in which two phenol molecules react with one H2O molecule with 100% atom-efficiency. In the scale-up experiment at the 1 g scale, NiPt/NHPC and FeRu/NHPC exhibit excellent durability and stability, which enables this integrated system to afford 645.3 mg of cyclohexanone and 691.7 mg of benzoquinone synchronously in an operating time of 90 h.

10.
Anal Chem ; 94(15): 5962-5969, 2022 04 19.
Artículo en Inglés | MEDLINE | ID: mdl-35380778

RESUMEN

Aberrant production of H2O2 is involved in cancer. The levels of H2O2 are significantly higher in tumor cells than in normal cells. It is important to develop fluorescent probes to image basal H2O2 selectively in tumor cells. So far, a cancer cell-targeting probe to image basal H2O2 has not been reported. Thus, we developed a fluorescent probe, BBHP, which contains benzil as a H2O2-recognition site and biotin as a target binding motif for the selective and sufficient detection of H2O2 in tumor cells. BBHP enables a selective fluorescence turn-on response to H2O2. The binding of the probe with biotin receptors can greatly accelerate the fluorescence response to H2O2. As a result, BBHP can sufficiently image basal H2O2 in biotin receptor-positive cancer cells and tumor tissues. Finally, BBHP was successfully applied to discriminate between cancerous and normal tissues.


Asunto(s)
Colorantes Fluorescentes , Peróxido de Hidrógeno , Biotina , Microscopía Fluorescente
11.
Proc Natl Acad Sci U S A ; 116(26): 12654-12659, 2019 06 25.
Artículo en Inglés | MEDLINE | ID: mdl-31182598

RESUMEN

Synthesis of liquid fuels (C5+ hydrocarbons) via CO2 hydrogenation is very promising. Hydrogenation of CO2 to liquid hydrocarbons usually proceeds through tandem catalysis of reverse water gas shift (RWGS) reaction to produce CO, and subsequent CO hydrogenation to hydrocarbons via Fischer-Tropsch synthesis (FTS). CO2 is a thermodynamically stable and chemically inert molecule, and RWGS reaction is endothermic and needs a higher temperature, whereas FTS reaction is exothermic and is thermodynamically favored at a lower temperature. Therefore, the reported technologies have some obvious drawbacks, such as high temperature, low selectivity, and use of complex catalysts. Herein we discovered that a simple Co6/MnOx nanocatalyst could efficiently catalyze CO2 hydrogenation. The reaction proceeded at 200 °C, which is much lower than those reported so far. The selectivity of liquid hydrocarbon (C5 to C26, mostly n-paraffin) in total product could reach 53.2 C-mol%, which is among the highest reported to date. Interestingly, CO was hardly detectable during the reaction. The in situ Fourier transform infrared characterization and 13CO labeling test confirmed that the reaction was not via CO, accounting for the eminent catalytic results. This report represents significant progress in CO2 chemistry and CO2 transformation.

12.
BMC Musculoskelet Disord ; 23(1): 274, 2022 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-35317764

RESUMEN

BACKGROUND: Osteoarthritis is a common and disabling condition that places heavy burden to individuals and healthcare systems. Patient education is a facilitator in the treatment decision making process, aiming to develop a treatment plan for the disease management. Electronic health (eHealth) is an alternative forum for the delivery of patient education and given the prevailing of eHealth in healthcare, introducing patient education programs using the technology has the potential to improve patient engagement, self-management and outcomes in patients with osteoarthritis. The study will evaluate the efficacy of eHealth patient education tool on patients' perception of knee osteoarthritis and treatment options, satisfaction and compliance to treatments. METHODS: This study is a prospective randomized controlled trial with a 1:1 allocation in two groups. We will recruit 216 patients diagnosed with knee osteoarthritis from the outpatient physiatry/physiotherapy clinic at West China Hospital, Sichuan University in Southwest China. Both groups will receive usual care and additionally, the intervention group will use eHealth patient education tool during the process. Measurements will be taken at baseline, post-intervention, 1 month, 3- and 6-months follow-up. Primary outcome will be patients' knowledge about disease and treatment options, measured by the validated osteoarthritis patient knowledge questionnaire. Secondary outcomes include patients' satisfaction with the consultation, the eHealth patient education tool, and their trust of the physiotherapist. DISCUSSION: The eHealth patient education tool is designed to provide participants with an innovative model of care delivery and this trial will assess the efficacy of the tool and whether this new model of patient education will have the potential to increase patient knowledge and empower self-management. Results collected from this study will further inform future research employing eHealth tool as interventions for the management of a range of other chronic conditions and help participants in communities or rural areas having the equal access to health care services. TRIAL REGISTRATION: This study was prospectively registered on the Chinese Clinical Trials Registry ( ChiCTR2100051083 ) registered 12.09.2021.


Asunto(s)
Osteoartritis de la Rodilla , Telemedicina , Electrónica , Humanos , Osteoartritis de la Rodilla/complicaciones , Osteoartritis de la Rodilla/diagnóstico , Osteoartritis de la Rodilla/terapia , Educación del Paciente como Asunto , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Telemedicina/métodos
13.
Small ; 17(41): e2102629, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34510751

RESUMEN

Electrochemical reduction of CO2 (CO2 RR) to formate is a promising route to prepare value-added chemical. Developing low-cost and efficient electrocatalysts with high product selectivity is still a grand challenge. Herein, a novel Cu anchored on hollow carbon spheres catalysts (HCS/Cu-x, x represents the mass of CuCl2 added in the system) is designed with controllable copper/carbon heterogenous interfaces. Rich copper/carbon heterogenous interfaces and hollow structure of optimized HCS/Cu-0.12 catalyst are beneficial to charge transmission. Compared with the CO2 RR occurred in aqueous electrolyte over Cu-based catalyst that has been reported to date, it exhibits highest formate Faradaic efficiency (FE) of 82.4% with a current density of 26 mA cm-2 and remarkable stability in a H-cell.


Asunto(s)
Dióxido de Carbono , Cobre , Carbono , Catálisis , Formiatos
14.
Org Biomol Chem ; 19(4): 911-919, 2021 01 28.
Artículo en Inglés | MEDLINE | ID: mdl-33416067

RESUMEN

Hydrogen polysulfides (H2Sn, n > 1), which are important reactive sulfur species, play crucial roles in H2S-related bioactivities, including antioxidation, cytoprotection, activation of ion channels, transcription factor functions and tumour suppression. Monitoring H2Snin vivo is of significant interest for exploring the physiological roles of H2Sn and the exact mechanisms of H2Sn-related diseases. Herein, we conceive a novel near-infrared fluorescent probe, NIR-CPS, that is used to detect H2Sn in living cells and in vivo. With the advantages of high sensitivity, good selectivity and a remarkably large Stokes shift (100 nm), NIR-CPS was successfully applied in visualizing H2Sn in living cells and mice. More importantly, NIR-CPS monitored H2Sn stimulated by lipopolysaccharide in tumour-bearing mice. These results demonstrate that the NIR-CPS probe is a potentially powerful tool for the detection of H2Snin vivo, thus providing a valuable approach in H2Sn-related medical research.


Asunto(s)
Colorantes Fluorescentes/química , Sulfuro de Hidrógeno/metabolismo , Rayos Infrarrojos , Imagen Óptica/métodos , Animales , Línea Celular Tumoral , Ratones
15.
Angew Chem Int Ed Engl ; 60(39): 21479-21485, 2021 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-34318968

RESUMEN

Oxidative cyanation of aldehydes provides a promising strategy for the cyanide-free synthesis of organic nitriles. Design of robust and cost-effective catalysts is the key for this route. Herein, we designed a series of Se,S,N-tri-doped carbon nanosheets with a hierarchical porous structure (denoted as Se,S,N-CNs-x, x represents the pyrolysis temperature). It was found that the obtained Se,S,N-CNs-1000 was very selective and efficient for oxidative cyanation of various aldehydes including those containing other oxidizable groups into the corresponding nitriles using ammonia as the nitrogen resource below 100 °C. Detailed investigations revealed that the excellent performance of Se,S,N-CNs-1000 originated mainly from the graphitic-N species with lower electron density and synergistic effect between the Se, S, N, and C in the catalyst. Besides, the hierarchically porous structure could also promote the reaction. Notably, the unique feature of this metal-free catalyst is that it tolerated other oxidizable groups, and showed no activity on further reaction of the products, thereby resulting in high selectivity. As far as we know, this is the first work for the synthesis of nitriles via oxidative cyanation of aldehydes over heterogeneous metal-free catalysts.

16.
Angew Chem Int Ed Engl ; 60(26): 14405-14409, 2021 06 21.
Artículo en Inglés | MEDLINE | ID: mdl-33825278

RESUMEN

Piperidine and δ-Lactam chemicals have wide application, which are currently produced from fossil resource in industry. Production of this kind of chemicals from lignocellulosic biomass is of great importance, but is challenging and the reported routes give low yield. Herein, we demonstrate the strategy to synthesize 2-methyl piperidine (MP) and 6-methylpiperidin-2-one (MPO) from biomass-derived triacetic acid lactone (TAL) that is produced microbially from glucose. In this route, TAL was firstly converted into 4-hydroxy-6-methylpyridin-2(1H)-one (HMPO) through facile aminolysis, subsequently HMPO was selectively transformed into MP or MPO over Ru catalysts supported on beta zeolite (Ru/BEA-X, X is the molar ratio of Si to Al) via the tandem reaction. It was found that the yield of MP could reach 76.5 % over Ru/BEA-60 in t-BuOH, and the yield of MPO could be 78.5 % in dioxane. Systematic studies reveal that the excellent catalytic performance of Ru/BEA-60 was closely correlated with the cooperative effects between active metal and acidic zeolite with large pore geometries. The related reaction pathway was studied on the basis of control experiments.


Asunto(s)
Lactamas/síntesis química , Piperidinas/síntesis química , Pironas/química , Biomasa , Lactamas/química , Estructura Molecular , Piperidinas/química
17.
Angew Chem Int Ed Engl ; 59(27): 11123-11129, 2020 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-32239780

RESUMEN

Electroreduction of CO2 to CO powered by renewable electricity is a possible alternative to synthesizing CO from fossil fuel. However, it is very hard to achieve high current density at high faradaic efficiency (FE). Here, the first use of N,P-co-doped carbon aerogels (NPCA) to boost CO2 reduction to CO is presented. The FE of CO could reach 99.1 % with a partial current density of -143.6 mA cm-2 , which is one of the highest current densities to date. NPCA has higher electrochemical active area and overall electronic conductivity than that of N- or P-doped carbon aerogels, which favors electron transfer from CO2 to its radical anion or other key intermediates. By control experiments and theoretical calculations, it is found that the pyridinic N was very active for CO2 reduction to CO, and co-doping of P with N hinder the hydrogen evolution reaction (HER) significantly, and thus the both current density and FE are very high.

18.
Angew Chem Int Ed Engl ; 59(23): 8896-8901, 2020 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-32134166

RESUMEN

Electrocatalytic reduction of CO2 to a single product at high current densities and efficiencies remains a challenge. However, the conventional electrode preparation methods, such as drop-casting, usually suffer from low intrinsic activity. Herein, we report a synthesis strategy for preparing heterogeneous electrocatalyst composed of 3D hierarchical Cu dendrites that derived from an in situ electrosynthesized hollow copper metal-organic framework (MOF), for which the preparation of the Cu-MOF film took only 5 min. The synthesis strategy preferentially exposes active sites, which favor's the reduction of CO2 to formate. The current density could be as high as 102.1 mA cm-2 with a selectivity of 98.2 % in ionic-liquid-based electrolyte and a commonly used H-type cell.

19.
Angew Chem Int Ed Engl ; 59(38): 16459-16464, 2020 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-32533630

RESUMEN

Electroreduction of CO2 to liquid fuels such as ethanol and n-propanol, powered by renewable electricity, offers a promising strategy for controlling the global carbon balance and addressing the need for the storage of intermittent renewable energy. In this work, we discovered that the composite composed of nitrogen-doped graphene quantum dots (NGQ) on CuO-derived Cu nanorods (NGQ/Cu-nr) was an outstanding electrocatalyst for the reduction of CO2 to ethanol and n-propanol. The Faradaic efficiency (FE) of C2+ alcohols could reach 52.4 % with a total current density of 282.1 mA cm-2 . This is the highest FE for C2+ alcohols with a commercial current density to date. Control experiments and DFT studies show that the NGQ/Cu-nr could provide dual catalytic active sites and could stabilize the CH2 CHO intermediate to enhance the FE of alcohols significantly through further carbon protonation. The NGQ and Cu-nr had excellent synergistic effects for accelerating the reduction of CO2 to alcohols.

20.
J Am Chem Soc ; 141(9): 4002-4009, 2019 03 06.
Artículo en Inglés | MEDLINE | ID: mdl-30739440

RESUMEN

Construction of N-substituted pyrrolidones from biomass-derived levulinic acid (LA) via reductive amination is a highly attractive route for biomass valorization. However, realizing this transformation using H2 as the hydrogen source under mild conditions is still very challenging. Herein, we designed porous TiO2 nanosheets-supported Pt nanoparticles (Pt/P-TiO2) as the heterogeneous catalyst. The prepared Pt/P-TiO2 was highly efficient for reductive amination of LA to produce various N-substituted pyrrolidones (34 examples) at ambient temperature and H2 pressure. Meanwhile, Pt/P-TiO2 showed good applicability for reductive amination of levulinic esters, 4-acetylbutyric acid, 2-acetylbenzoic acid, and 2-carboxybenzaldehyde. Systematic studies indicated that the strong acidity of P-TiO2 and the lower electron density of the Pt sites as well as the porous structure resulted in the excellent activity of Pt/P-TiO2.

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