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1.
Small ; : e2403268, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38747023

RESUMEN

Metal-organic framework derived materials received a lot of attention due to their significant benefits in photocatalytic reactions. In this work, a Z-scheme ZnIn2S4/Bi2S3 hierarchical heterojunction is first developed by a one-pot method using CAU-17 as a template. The specific preparation method endows an intimate interface contact between these two monomers, and CAU-17-derived Bi2S3 possesses a high surface area and porosity, resulting in an efficient charge separation and O2 capture. Thus, for photocatalytic H2O2 production from the O2 reduction reaction, the ZnIn2S4/Bi2S3 heterojunction can achieve an H2O2 yield of 995 µmol L-1 in pure water and ambient air under visible light, 4.5 and 4 times that of ZnIn2S4 and Bi2S3, respectively. In addition, in tetracycline solution, ZnIn2S4/Bi2S3 can degrade tetracycline with a degradation rate of 95% by photocatalysis, and at the same time, a final H2O2 production yield of 1223 µmol L-1 is reached. Similarly, high yields of H2O2 are also obtained from wastewater containing o-nitrophenol, acid golden yellow, or acid red, and these pollutants are effectively degraded. This work reveals the potential of metal-organic framework-derived materials in photocatalysis, as well as provides insights into H2O2 green synthesis and wastewater treatment.

2.
Angew Chem Int Ed Engl ; 62(6): e202215737, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36478093

RESUMEN

Via hydrothermal synthesis of Sn-Al gels, mild dealumination and ion exchange, a bimetallic Sn-Ni-Beta catalyst was prepared which can convert glucose to methyl lactate (MLA) and methyl vinyl glycolate (MVG) in methanol at yields of 71.2 % and 10.2 %, respectively. Results from solid-state magic-angle spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, transmission electron microscopy, spectroscopic analysis, probe-temperature-programmed desorption, and density functional theory calculations conclusively reveal that the openness of the Sn sites, such as by the formation of [(SiO)3 -Sn-OH] entities, is governed by an adjacent metal cation such as Ni2+ , Co2+ , and Mn2+ . This relies on the low structure-defective pore channel, provided by the current synthesis scheme, and the specific silica hydroxyl anchor point is associated with the incorporation of Sn for additional and precise metal ion localization. The presence of metal cations significantly improved the catalytic performance of Sn-Ni-Beta for glucose isomerization and conversion to MLA of sugar compared with Sn-Beta.

3.
J Sep Sci ; 41(10): 2188-2196, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29469237

RESUMEN

We propose a method for the simultaneous determination of 15 kinds of polycyclic aromatic hydrocarbons in marine samples (muscle) employing gas chromatography with mass spectrometry after saponification with ultrasound-assisted extraction and solid-phase extraction. The experimental conditions were optimized by the response surface method. In addition, the effects of different lyes and extractants on polycyclic aromatic hydrocarbons extraction were discussed, and saturated sodium carbonate was first used as the primary saponification reaction and extracted with 10 mL of ethyl acetate and secondly 1 mol/L of sodium hydroxide and 10 mL of n-hexane were used to achieve better results. The average recovery was 67-112%. Satisfactory data showed that the method has good reproducibility with a relative standard deviation of <13%. The detection limits of polycyclic aromatic hydrocarbons were 0.02-0.13 ng/g. Compared with other methods, this method has the advantages of simple pretreatment, low solvent consumption, maximum polycyclic aromatic hydrocarbons extraction, the fast separation speed, and the high extraction efficiency. It is concluded that this method meets the batch processing requirements of the sample and can also be used to determine polycyclic aromatic hydrocarbons in other high-fat (fish, shrimp, crab, shellfish) biological samples.


Asunto(s)
Análisis de los Alimentos/métodos , Cromatografía de Gases y Espectrometría de Masas , Hidrocarburos Policíclicos Aromáticos/análisis , Alimentos Marinos/análisis , Extracción en Fase Sólida , Algoritmos , Animales , Braquiuros , Peces , Contaminación de Alimentos , Modelos Estadísticos , Penaeidae , Reproducibilidad de los Resultados , Mariscos , Solventes
4.
Zhonghua Bing Li Xue Za Zhi ; 43(6): 375-8, 2014 Jun.
Artículo en Zh | MEDLINE | ID: mdl-25208986

RESUMEN

OBJECTIVE: To study the clinicopathologic characteristics, immunophenotypes and differential diagnosis of primitive myxoid mesenchymal tumor of infancy (PMMTI). METHODS: The clinical data, histological features and immunohistochemic results of 3 cases of PMMTI were reviewed. RESULTS: There were 2 males and 1 female aged 4 years, 2 days and 3 months respectively. The tumor occurred in the head and neck (n = 2), and lumbar regions (n = 1).Histologically, they were composed of ovoid, short spindled to polygonal mesenchymal cells with less eosinophilic cytoplasm, or vacuolated cytoplasm. There was mild nuclear atypia with mitotic activity of 0-2/10 HPF.In most areas, the neoplastic cells showed a diffuse growth pattern, whereas in some areas, they formed a vaguely nodular pattern with peripheral collagenized stroma. They were embedded in a myxoid stroma that contained a rich delicate vascular network. Besides, small cyst-like spaces were also present in one case. The tumor cells expressed vimentin, but not alpha smooth muscle actin, desmin, myogenin, S-100 protein, CD34 and cytokeratin. The patients underwent surgery.One patient had local recurrences twice and died 2 years later. Compared with the primary tumor, the recurrent lesions exhibited increased cellularity, marked cellular atypia and mitotic activity (10/10 HPF). The other two patients remained well with no evidence of disease at last during follow-up. CONCLUSIONS: PMMTI is a rare soft tissue tumor of infancy, composed of primitive mesenchymal cells and myxoid stroma.It occurs mainly in the somatic soft tissues of the trunk, head and neck region, and the extremities, and is characterized by a high rate of local recurrence if incompletely excised. Metastasis and tumor related death may occur, albeit very rarely.Increased awareness of this novel entity will help avoid misinterpreting the lesion as a variety of other infantile mesenchymal neoplasms, including congenital fibrosarcoma and lipoblastoma.


Asunto(s)
Neoplasias de los Tejidos Blandos/patología , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Neoplasias de los Tejidos Blandos/metabolismo , Vimentina/metabolismo
5.
Stem Cell Res ; 77: 103425, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38653148

RESUMEN

The KCNQ1 gene encodes a voltage-gated potassium channel, which plays an important role in the repolarization of myocardial action potentials. Mutations in this gene often result in type 1 long QT syndrome (LQT1). Here, we generated a KCNQ1 (c.1032 + 2 T > C) mutant human embryonic stem cell line (WAe009-A-1D) based on the transient expression adenine base editing system that converts base A to G. The WAe009-A-1D cell maintains the morphology, pluripotency, and normal karyotype of the stem cells and is capable of differentiating into all three germ layers in vivo.


Asunto(s)
Edición Génica , Células Madre Embrionarias Humanas , Canal de Potasio KCNQ1 , Humanos , Canal de Potasio KCNQ1/genética , Canal de Potasio KCNQ1/metabolismo , Células Madre Embrionarias Humanas/metabolismo , Células Madre Embrionarias Humanas/citología , Línea Celular , Sistemas CRISPR-Cas , Diferenciación Celular , Mutación
6.
Ann N Y Acad Sci ; 1537(1): 140-154, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38924165

RESUMEN

Considerable debate exists about the interplay between auditory and motor speech systems. Some argue for common neural mechanisms, whereas others assert that there are few shared resources. In four experiments, we tested the hypothesis that priming the speech motor system by repeating syllable pairs aloud improves subsequent syllable discrimination in noise compared with a priming discrimination task involving same-different judgments via button presses. Our results consistently showed that participants who engaged in syllable repetition performed better in syllable discrimination in noise than those who engaged in the priming discrimination task. This gain in accuracy was observed for primed and new syllable pairs, highlighting increased sensitivity to phonological details. The benefits were comparable whether the priming tasks involved auditory or visual presentation. Inserting a 1-h delay between the priming tasks and the syllable-in-noise task, the benefits persisted but were confined to primed syllable pairs. Finally, we demonstrated the effectiveness of this approach in older adults. Our findings substantiate the existence of a speech production-perception relationship. They also have clinical relevance as they raise the possibility of production-based interventions to improve speech perception ability. This would be particularly relevant for older adults who often encounter difficulties in perceiving speech in noise.


Asunto(s)
Ruido , Percepción del Habla , Humanos , Percepción del Habla/fisiología , Femenino , Masculino , Adulto , Adulto Joven , Anciano , Habla/fisiología , Fonética , Persona de Mediana Edad
7.
RSC Adv ; 14(32): 23322-23331, 2024 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-39049885

RESUMEN

Nanofluid application in enhanced oil recovery (EOR) recently emerged and garnered significant attention within the field. Nanofluids possess unique properties of reducing oil-water interfacial tension, stabilizing emulsions, altering rock surface wettability, and enhancing disjoining pressure between crude oil and rock surfaces, therefore have potential for the oil recovery process. This review provides an in-depth exploration of various aspects related to nanofluids in EOR. Different types of nanofluids are presented with their preparation methods and representative properties. More importantly, the disjoining pressure, a key physical concept in nanofluid-assisted EOR, is introduced and discussed in terms of the mechanism of oil displacement and measurement methods. Further understanding the role of disjoining pressure in nanofluid-assisted oil displacement is necessary for the development and application of effective nanofluids for EOR.

8.
RSC Adv ; 13(44): 30718-30725, 2023 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-37869394

RESUMEN

As the initial process of preparing transparent conductive oxide materials from monobutyltin chloride (MBTC) to tin oxide, the hydrolysis and condensation of MBTC to form a dimer Sn2 play a critical role. However, the specific mechanism of this process is still unclear. Here we develop a step-by-step searching method based on density functional theory calculation and empirical chemical criteria to determine possible reaction pathways and reveal the most likely reaction mechanism. The wave function analyses of various intermediate species provide more insights into the changes of atomic charge population, chemical bond strength, and coordination situation of central tin in the reaction process. Further investigation on the ring-containing Sn2 reveals the existence of unique three-center four-electron (3c-4e) interactions to stabilize the four-membered Sn2O2 ring structure, which serves as the true driving force for dimerization reaction. These results provide a more detailed understanding of the hydrolysis and condensation process of MBTC and would be helpful for the future optimization of the preparation process of tin oxide films.

9.
Bioresour Technol ; 372: 128653, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36682474

RESUMEN

Aviation fuel is high energy density and is usually produced from refinery in petroleum industry. Production of renewable aviation fuel from biomass eases pressure of carbon emission regulation. The operational processes in this study include steam stripping, hydrolysis of residues, condensation reaction unit, autoclave hydrogenation, fixed-bed hydrodeoxygenation, and oil-upgrading unit. The biomass-derived aviation fuel has a low oxygen content of 0.4 %, while its high heat value is 45.5 MJ/kg. The aviation fuel ranges from C8 âˆ¼ C15, and rich in isoparaffins (50.4 %) while the n-paraffins have a selectivity of 12.2 % and other components are cycloparaffins (19.0 %), aromatic hydrocarbons (11.3 %), and alkenes (5.6 %). The mass yield for aviation fuel from corn stover reaches 10.6 %. This pilot study achieved production of aviation fuel from raw biomass corn stover.


Asunto(s)
Aviación , Zea mays , Proyectos Piloto , Calor , Hidrogenación , Biomasa
10.
Medicine (Baltimore) ; 101(41): e28090, 2022 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-36254072

RESUMEN

BACKGROUND: The efficacy of irinotecan as the adjunctive therapy to fluorouracil and leucovorin remains controversial in patients with colorectal cancer. We conduct this meta-analysis to explore the efficacy of irinotecan supplementation for colorectal cancer. METHODS: We have searched PubMed, EMBASE, Web of science, EBSCO, and Cochrane library databases through March 19, 2020, and included randomized controlled trials assessing the efficacy of irinotecan plus fluorouracil and leucovorin for colorectal cancer. RESULTS: Five randomized controlled trials were included in the meta-analysis. Compared with fluorouracil and leucovorin for colorectal cancer, irinotecan supplementation could significantly improve progression-free survival rate (hazard ratio = 0.72; 95% confidence interval [CI] = 0.58-0.90; P = .003), median progression-free survival (standard mean difference = -0.30; 95% CI = -0.44 to -0.15; P < .0001), overall survival rate (hazard ratio = 0.77; 95% CI = 0.66-0.90; P = .001), and objective response (risk ratio [RR] = 0.57; 95% CI = 0.49-0.66; P < .00001) and decrease progressive disease (RR = 2.10; 95% CI = 1.40-3.14; P = .0003), but revealed no obvious effect on complete response (RR = 0.88; 95% CI = 0.33-2.29; P = .79). The incidence of grade ≥3 adverse events in irinotecan supplementation group was increased compared to control group (RR = 0.67; 95% CI = 0.57-0.79; P < .00001). CONCLUSIONS: Irinotecan as the adjunctive therapy to fluorouracil and leucovorin can increase the survival and objective response of patients with colorectal cancer, but the incidence of grade ≥3 adverse events is found to be increased after irinotecan supplementation.


Asunto(s)
Camptotecina , Neoplasias Colorrectales , Humanos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Camptotecina/uso terapéutico , Suplementos Dietéticos , Fluorouracilo/uso terapéutico , Irinotecán/uso terapéutico , Leucovorina/uso terapéutico , Ensayos Clínicos Controlados Aleatorios como Asunto
11.
ChemSusChem ; 15(13): e202200092, 2022 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-35441445

RESUMEN

2-Hexanol (2-HOL) is a versatile biomass-derived platform molecule for synthesis of liquid transportation fuels, lubricants, or detergents. Herein, a one-step preparation of 2-HOL using 5-hydroxymethylfurfural (HMF) as a substrate was reported for the first time. Several Au-based catalysts supported on different metal oxides were prepared to explore the relationship between carrier and catalytic activity. The results showed that the highest 2-HOL yield of 65.8 % was obtained at complete HMF conversion over the 5 %Au/ZrO2 catalyst. The 5 %Au/ZrO2 catalyst exhibited excellent durability after five consecutive recycling runs, while confirming its remarkable ring-opening hydrogenolysis on other biomass-derived furanics, furfural, with a total yield of 1-pentanol and 2-pentanol of 67.4 %. The distinguished ring-opening hydrogenolysis performance of the Au/ZrO2 catalyst originated from a synergistic effect between the interfacial Au-O-Zr oxygen vacancies-induced Lewis acidic sites (activating C-OH/C=O bonds) and metallic Au (activating H2 ). This work provides a possibility for producing 2-HOL from HMF with high yield, expanding the sustainable application of lignocellulosic biomass.


Asunto(s)
Furaldehído , Hexanoles , Catálisis , Furaldehído/análogos & derivados , Furaldehído/química
12.
RSC Adv ; 12(26): 16847-16859, 2022 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-35754887

RESUMEN

Alanine (Ala), regarded as the building block for protein synthesis, has been widely used in the field of food processing, pharmaceutical, and bio-based plastic industries. Containing plenty of oxygenic functional groups, biomass-derived chemicals are proper for Ala synthesis in an economic and green way via amination. In this work, lactic acid (LA) derived from renewable biomass and waste glycerol (the major by-product of biodiesel industry) was used to produce Ala. Here, a series of magnetic catalysts M/Ni@C (M = Ru, Pt, Pd, Ir, and Rh) were synthesized by ethylene glycol reduction of metal M supported on encapsulated Ni@C. Compared with catalysts based on other M metals, Ru/Ni@C catalysts exhibited extraordinary efficiency with 91.4% selectivity for Ala synthesis from LA (63.7% yield of Ala and 69.7% conversion of LA). The results of experiments and catalyst characterization indicated that the doping of M metals could improve the dehydrogenation ability of catalysts, as well as the ability of NH3 adsorption, facilitating the reaction towards Ala. Overall, this study provides an efficient chemo-catalytic way for the production of Ala from biomass-derived substrates.

13.
Bioresour Technol ; 352: 127095, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35367326

RESUMEN

Both alkaline organosolv and formaldehyde stabilization pretreatment can yield high-quality lignin by preventing condensation. For the hydrogenolysis of the pretreated solid residues, the highest yield of C2-C4 chemicals was 66.8% under alkaline organosolv pretreatment for 60 min. Specifically, the crimped fibers and residual lignin and hemicellulose increased the surface roughness of the residue by 40.6%, the crystallinity index decreased to 44.4%, and the crystal size was reduced to 2.15 nm, which in turn promoted hydrogenolysis of the residue. However, the increase of crystallinity and crystal size and the decrease in surface roughness of the formaldehyde stabilization pretreatment residue greatly hindered the conversion of polysaccharides. In addition, residual formaldehyde on the residue may also inhibit catalyst activity. Overall, this study provides novel perspectives on the full utilization of biomass, as well as new insights into the conversion of polysaccharides.


Asunto(s)
Lignina , Polisacáridos , Biomasa , Catálisis , Formaldehído/química , Hidrólisis , Lignina/química , Polisacáridos/química
14.
Bioengineering (Basel) ; 9(9)2022 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-36134979

RESUMEN

Synthetic nanocarriers are a promising therapeutic delivery strategy. However, these systems are often hampered by inherent disadvantages such as strong biotoxicity and poor biocompatibility. To overcome these issues, biological carriers with commonly used chemotherapy drugs have been developed. In this work, engineered bacterial ghosts (BGs) originated from probiotic Escherichia coli Nissle 1917 (EcN) were devised to specifically target acidic extracellular environments of tumor tissue. To improve the production efficiency and safety, a novel lysis protein E from phage α3 was applied to produce EcN BGs under high growth densities in high quality. In addition, the acidity-triggered rational membrane (ATRAM) peptides were displayed in EcN BGs to facilitate specific cancer cell internalization within the acidic tumor microenvironment before drug release. In conclusion, the engineered EcN BGs offer a promising means for bionic bacteria construction for hepatocellular carcinoma therapy.

15.
Front Aging Neurosci ; 14: 865430, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35615597

RESUMEN

Objective: In this study, the regional homogeneity (ReHo) method was used to investigate levels of cerebral homogeneity in individuals with age-related macular degeneration (AMD), with the aim of exploring whether these measures are associated with clinical characteristics. Materials and Methods: Patients with AMD and healthy controls attending the First Affiliated Hospital of Nanchang University were invited to participate. Resting state functional magnetic resonance images were recorded in each participant and levels of synchronous neural activity were evaluated using ReHo. Receiver operating characteristic (ROC) curves were used to evaluate the sensitivity and specificity of this method. Results: Eighteen patients with AMD (9 males and 9 females) and 15 healthy controls (HCs) were recruited. The two groups were approximately matched in age, gender and weight. Compared with controls, the ReHo values were significantly higher in the AMD group at the limbic lobe and parahippocampal gyrus, and were significantly reduced at the cingulate gyrus, superior frontal gyrus, middle frontal gyrus, inferior parietal lobule, and precentral gyrus. Mean ReHo values at the cingulate gyrus and the superior frontal gyrus were negatively correlated with clinical symptoms. Conclusion: Brain neural homogeneity dysfunction is a manifestation of visual pathways in AMD patients, and may be one of the pathological mechanisms of chronic vision loss, anxiety and depression in AMD patients. In addition, the ReHo data may be useful for early screening for AMD.

16.
Bioresour Technol ; 347: 126403, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-34826560

RESUMEN

Herein, WOx-decorated Ir/SiO2 (W/Ir = 0.06) and HZSM-5 were coupled to selectively convert microcrystalline cellulose (MCC) into C6 alkanes. A 92.8% yield of liquid alkanes including an 85.3% yield of C6 alkanes was produced at 210 °C. Cellulose hydrolysis, glucose hydrogenation and sorbitol hydrodeoxygenation were integrated to produce alkanes via a sorbitol route. Ir-WOx/SiO2 showed high performance for hydrogenation and hydrodeoxygenation reactions after hydrolysis catalyzed by HZSM-5. The intimate contact between WOx and Ir enhanced the synergistic interaction through the electron transfer from Ir to WOx. The interaction strengthened the reduction capability of Ir for hydrogenations, as well as improved the adsorption and activation of C-O bonds on reduced WOx for deoxygenations. The monotungstate WOx species provided moderate Lewis acids to cooperate with Ir to accelerate hydrodeoxygenations with alleviated retro-aldol condensation to yield more C6 alkanes.


Asunto(s)
Alcanos , Dióxido de Silicio , Catálisis , Celulosa , Iridio , Óxidos , Tungsteno
17.
Plant Physiol Biochem ; 165: 57-70, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34034161

RESUMEN

Universal Stress Protein A (USPA) plays critical roles in the regulation of growth, development and response to abiotic stress in plants. To date, most research related to the role of USPA in plants has been carried out in herbaceous models such as Arabidopsis, rice and soybean. Here, we used bioinformatics approaches to identify 21 USPA genes in the genome of Vitis vinifera L. Phylogenetic analysis revealed that VvUSPAs could be divided into eight clades. Based on predicted chromosomal locations, we identified 16 pairs of syntenic, orthologous genes between A. thaliana and V. vinifera. Further promoter cis-elements analysis, together with identification of potential microRNA (miRNA) binding sites, suggested that at least some of the VvUSPAs participate in response to phytohormones and abiotic stress. To add support for this, we analyzed the developmental and stress-responsive expression patterns of the homologous USPA genes in the drought-resistant wild Vitis yeshanensis accession 'Yanshan-1' and the drought-sensitive Vitis riparia accession 'He'an'. Most of the USPA genes were upregulated in different degrees in the two genotypes after drought stress and exposure to ethephon (ETH), abscisic acid (ABA) and methyl jasmonate (MeJA). Individual USPA genes showed various tissue-specific expression patterns. Heterologous expression of five selected genes (VvUSPA2, VvUSPA3, VvUSPA11, VvUSPA13 and VvUSPA16) in Escherichia coli (E. coli) enhanced resistance to drought stress. Our study provides a model for mapping gene function in response to abiotic stress and identified three candidate genes, VvUSPA3, VvUSPA11 and VvUSPA16, as regulators of drought response in V. vinifera.


Asunto(s)
Vitis , Escherichia coli/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Choque Térmico , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteína Estafilocócica A , Estrés Fisiológico/genética , Vitis/genética , Vitis/metabolismo
18.
ACS Omega ; 5(36): 23322-23333, 2020 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-32954183

RESUMEN

To reveal the hydrothermal conversion routes of the biomass-derived furanic compounds, the soluble products formed during the hydrothermal conversion of 5-hydroxymethylfurfural (HMF), furfural, and furfuryl alcohol were analyzed by liquid chromatography-mass spectrometry (LC-MS) and LC-MS/MS. Multiple carbocyclic compounds containing hydroxy group and carbonyl group were detected, with a molecular mass in the range of 154-272 Da and carbon chain of the length 8-15. The formation of these soluble carbocyclic compounds was proposed to involve hydrolytic ring-opening of the furanic ring, intermolecular aldol condensation, intramolecular aldol condensation, and C-C cleavage reaction. The C-C cleavage reaction was proposed to occur on the dicarbonyl structure of the formed primary polymers.

19.
ACS Omega ; 5(30): 19140-19150, 2020 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-32775916

RESUMEN

The soluble byproducts formed during the hydrothermal conversion of cellulose catalyzed by solid tungstated alumina (AlW) were analyzed by LC-MS and LC-MS2 to determine their formulas and possible structures. These identified soluble compounds could be roughly divided into four species of carboxylic acids, α-carbonyl aldehydes, carbocyclic compounds, and furanic compounds with molecular mass in the range of 90-220 Da. Compared with the noncatalytic condition, the addition of AlW could increase the selectivity of carboxylic acids (especially α-hydroxy acid) from cellulose and suppress the formation of furanic compounds, carbocyclic compounds, and hydrochar. Based on the product distribution, the hydrothermal conversion route of glucose was proposed by regarding the formed α-carbonyl aldehydes as the key intermediates for formation of carboxylic acids, carbocyclic compounds, and furanic compounds.

20.
RSC Adv ; 10(61): 37014-37022, 2020 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-35521235

RESUMEN

Anthraquinones are recognized as high efficiency photocatalysts which can perform various redox reactions in aqueous or organic phases. We have experimentally proven that 2-BrAQ can undergo hydrogen transfer with an alpha-aromatic alcohol under light conditions, thereby efficiently oxidizing the aromatic alcohol to the corresponding product. The yield of 1-phenethanol to acetophenone can reach more than 96%. In subsequent catalyst screening experiments, it was found that the electronegativity of the substituent at the 2 position of the anthraquinone ring and the acidity of the solvent affect the photocatalytic activity of anthraquinones. After using various aromatic alcohol substrates, 2-BrAQ showed good conversion and selectivity for most aromatic alcohols, but showed C-C bond cleavage and low selectivity with non-α-position aromatic alcohols. In order to explore the mechanism of the redox reaction of 2-BrAQ in acetonitrile solution, the corresponding free radical reaction pathway was proposed and verified by density functional theory (DFT). Focusing on calculations for 2-BrAQ during the reaction and the first-step hydrogen transfer reaction between the 2-BrAQ triplet molecule and the 1-phenylethanol molecule, we recognized the changes that occurred during the reaction and thus have a deeper understanding of the redox reaction of anthraquinone compounds in organic systems.

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