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1.
Small ; : e2005801, 2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-33470501

RESUMEN

As a new member of 2D materials, 2D tellurium (Te) has recently attracted much attention due to its intriguing properties. Through hydrothermal processing, 2D Te with tunable thickness and size has been realized, and its growth mechanism has also been studied. However, the tailored growth of 2D Te nanoflakes with symmetrical morphologies and interfacial moiré fringes has never been reported. Here, 2D Te nanoflakes have been prepared using the hydrothermal method, and mirror-symmetrical shapes (including "V-shape," "heart-shape," and "paper airplane-shape") with obvious moiré fringes in the middle of the nanoflakes are observed. Comprehensive transmission electron microscopy (TEM) techniques are utilized for structural characterization of these nanoflakes, especially the moiré fringes in the symmetry axis region of the nanoflakes. The systematic analyses of the moiré fringes and the observation of obvious overlapping edges of the composing nanoflakes from the cross-sectional samples reveal the possible mechanism of morphological evolution for these symmetrical nanoflakes. These details may fill the research gap in the controllable growth of 2D Te nanomaterials, pave the way for the fabrication of 2D Te moiré superlattices and in-plane homojunctions, and promote their future versatile applications.

2.
ChemSusChem ; 2020 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-33090706

RESUMEN

Levulinic acid (LA) is acknowledged one of the most promising biomass-derived platform molecules and can be transformed into various value-added chemicals. Here, we report a new reaction process for the valorization of LA derivatives under transition-metal-free condition. The protocol combined with the conversion of the levulinate to tosylhydrazone and base promoted arylation, acylation, and etherification cross-coupling. Moreover, our method was applied to synthesize three biologically active molecules, rac-curcumene, rac-xanthorrhizol and rac-4,7-dimethyl-l-tetralone. This reaction discloses a new avenue for the high-value utilization of platform molecules.

3.
PLoS One ; 15(6): e0235090, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32569270

RESUMEN

Tumor is a prevalent great threat to public health worldwide and multidrug resistance (MDR) of tumor is a leading cause of chemotherapy failure. Nanomedicine has shown prospects in overcoming the problem. Doxorubicin (DOX), a broad-spectrum anticancer drug, showed limited efficacy due to MDR. Herein, a doxorubicin containing pectin nanocell (DOX-PEC-NC) of core-shell structure, a pectin nanoparticle encapsulated with liposome-like membrane was developed. The DOX-PEC-NC, spheroid in shape and sized around 150 nm, exerted better sustained release behavior than doxorubicin loading pectin nanoparticle (DOX-PEC-NP) or liposome (DOX-LIP). In vitro anticancer study showed marked accumulation of doxorubicin in different tumor cells as well as reversal of MDR in HepG2/ADR cells and MCF-7/ADR cells caused by treatment of DOX-PEC-NC. In H22 tumor-bearing mice, DOX-PEC-NC showed higher anticancer efficacy and lower toxicity than doxorubicin. DOX-PEC-NC can improve anticancer activity and reduce side effect of doxorubicin due to increased intracellular accumulation and reversal of MDR in tumor cells, which may be a promising nanoscale drug delivery vehicle for chemotherapeutic agents.


Asunto(s)
Antineoplásicos/uso terapéutico , Doxorrubicina/uso terapéutico , Sistemas de Liberación de Medicamentos , Resistencia a Múltiples Medicamentos , Resistencia a Antineoplásicos , Nanopartículas/química , Pectinas/química , Animales , Antineoplásicos/farmacología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Doxorrubicina/farmacología , Liberación de Fármacos , Humanos , Concentración 50 Inhibidora , Masculino , Ratones , Nanopartículas/ultraestructura , Bazo/patología , Timo/patología
4.
Int J Biol Macromol ; 156: 565-575, 2020 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-32311401

RESUMEN

In this study, we investigated the gellan gelation mechanism induced by Glucono-δ-lactone (GDL) addition, and subsequently we further fabricated a series of thermally irreversible emulsion gels with the GDL-induced gel matrix as the continuous phase and the methyl cellulose (MC) stabilized emulsion as the dispersed phase. The results showed that GDL- induced gellan gelation was both a time- and temperature-dependent process, which was similar to the gelation process of NaCl-induced gellan gels, but with a higher temperature-dependence. Moreover, GDL-induced gel had a significantly higher rupture strength and the resulting gel did not melt on heating, meaning that the GDL-induced gellan gel can be deemed thermally irreversible. This is because decreasing pH is commonly more effective in promoting gellan gelation. Besides, by mixing the MC-stabilized emulsion with a hot gellan sol, followed by adding GDL, we fabricated the emulsion gels with a wide range of oil phase fraction (0-30%). The emulsion gels exhibited good thermal stability, without melting and oil droplet coalescence observed when heating the gels in a boiling water bath for 30 min. Conclusively, our results may deepen the understanding on gellan gelation induced by GDL and also broaden the utilization of gellan in building gel-related food structures.

5.
Org Lett ; 22(8): 2941-2945, 2020 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-32250638

RESUMEN

Ene-allenes serve as versatile building blocks in organic synthesis, and the development of their efficient preparation is valuable. Herein the synthesis of boryl-substituted ene-allenes utilizing a Cu/Pd-catalyzed borylallenylation of alkynes with propargylic carbonates and bis(pinacolato)diboron is reported. Densely (tetra-, penta-, and hexa-) substituted ene-allenes were synthesized in acceptable yield with high regio- and stereoselectivity. More important molecule structures can be obtained by subsequent modifications.

6.
Org Lett ; 22(4): 1414-1419, 2020 02 21.
Artículo en Inglés | MEDLINE | ID: mdl-32011150

RESUMEN

Herein, we describe a palladium-catalyzed alkynylation of gem-difluorinated cyclopropanes via C-C bond activation/C-F bond cleavage, followed by C-C(sp) coupling. The new approach proceeds with broad substrate scope under mild reaction conditions, whereas both 1,1-disubstituted and complex-molecule-modified gem-difluorinated cyclopropanes react smoothly with high stereoselectivity. The developed method provides efficient and convenient ways access to diversity of important fluorinated enynes and arenes by slightly modification of the reaction conditions.

7.
Bioorg Chem ; 96: 103625, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32028059

RESUMEN

In this study, the inhibitory activity of young apple polyphenols (YAP) on α-glucosidase was investigated. Composition and inhibition analyses suggested that tannic acid (TA), (-)-epicatechin (EC) and phlorizin (PH) were the main active constituents in YAP showing α-glucosidase inhibition. PH was a competitive inhibitor, while YAP, TA and EC were the mixed-type ones. YAP, TA, PH and EC quenched the fluorescence spectrum of α-glucosidase significantly. Interestingly, the constants that indicate binding interaction between α-glucosidase and TA, PH, EC, including reciprocal of competitive inhibition constant (1/Kic), fluorescence quenching constant (KFQ) and binding energy (Eb), were shown similar orders as TA > PH > EC, contrary to IC50 values. This indicates that binding interactions between polyphenols and α-glucosidase caused the enzyme inhibition. Additionally, potential enzyme unfolding by polyphenols interactions indicated by red-shift of maximum emission wavelength is supported by the decrease in α-helix and ß-sheet contents of the enzyme. Conclusively, the α-glucosidase inhibition indicates that YAP may have potentials in alleviation of type 2 diabetes symptom.

8.
Int J Biol Macromol ; 151: 257-267, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32057870

RESUMEN

In this study, a class of interpenetrating network (IPN) gels were successfully fabricated based on glucono-δ-lactone (GDL) induced gelation of mixed alginate (Alg) and deacylated gellan (gellan) systems. The IPN gels were prepared by co-hydrating a mixed Alg and gellan powder, followed by adding GDL and calcium carbonate (CaCO3) in sequence to initiate the gelation. It was found that Alg and gellan can form independently a gel network, with no significant interaction between the two types of gel networks observed, as indicated by the results of gel strength determination, scanning electron microscope (SEM) observations and thermogravimetry (TG) and derivative thermogravimetric (DTG) analyses. Moreover, the mixing ratio of Alg to gellan significantly affected the physical properties of the fabricated gels. With increasing Alg to gellan ratio, the gels tended to become more elastic, and to show a higher rehydration rate and rehydration extent. Overall, these tunable properties may allow the fabricated gels to find potential applications in designing or optimizing the structures of gel-related food products.

9.
Chem Commun (Camb) ; 56(15): 2340-2343, 2020 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-31993594

RESUMEN

The Cu/Pd-catalyzed boryldifluoroallylation of alkynes was achieved, providing the corresponding skipped gem-difluorodiene scaffolds with high regio- and stereoselectivity in moderate to excellent yields. This new approach has good functional group compatibility for both alkynes and 3,3-difluoro-substituted allylic esters. Moreover, an array of synthetic building blocks, skipped dienes, trienes, and drug mimics can be obtained via further transformations.

10.
Int J Biol Macromol ; 146: 821-831, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31726145

RESUMEN

In this study, a series of emulsion gels were prepared by dispersing emulsified oil droplets into alginate (Alg) gel matrix, and the final emulsion gels contained 2% Alg (w/v), 0.5% Tween 80 (v/v) and gradient concentrations of oil phase fractions (5-30%, v/v). Subsequently, the effects of Ca2+ addition, heating, and freeze thawing treatments on the emulsion gels were also investigated by a combination of rheological tests, confocal and scanning electron microscopy techniques. It was found that within the range of 0-30% of oil phase fraction, 0-0.15% of CaCl2 addition (w/v), all the emulsion gels could achieve significant thixotropy and good emulsion stability, without discernible oil droplet coalescence observed after heating and/or freeze thawing treatments. The yield stress value and gel stiffness increased with increasing oil phase fraction and Ca2+ addition, which is attributed to the strengthened gel network cross-links in the emulsion gels, as confirmed by SEM results. Interestingly, after freeze thawing treatment, the gel stiffness was slightly improved, which may be due to the intermolecular self-association of Alg during freezing stage. Overall, these results show the potential application of Alg-stabilized emulsion gels in preparation of low-fat mayonnaise products and other similar emulsion foods.


Asunto(s)
Alginatos/química , Emulsiones/química , Geles/química , Lípidos/química , Calcio/química , Congelación , Aceites/química , Reología , Temperatura
11.
Carbohydr Polym ; 229: 115468, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-31826449

RESUMEN

In this study, the compatibility of alginate (Alg) and konjac glucomannan (KGM) in aqueous solutions was evaluated by dilute solution viscometry (DSV). It was found that when Alg: KGM ratio was lower than 6:4 (w/w), Alg and KGM were compatible, which was subsequently confirmed by SEM, AFM and TEM. Moreover, by dispersing emulsified oil droplets into Alg gel matrix, followed by addition of KGM to thicken the system, where the ratio of Alg: KGM was 5:5, a class of emulsion gels with significant thixotropy and viscoelasticity could be obtained. The prepared emulsion gels displayed good thermal stability and freeze-thaw stability, with no oil droplet coalescence observed after heating at 100°C for 30 min or freezing the gels at -18°C for 24 h. Overall, the mixed Alg/KGM system is expected to provide a template for designing low-fat mayonnaise-like food emulsions.


Asunto(s)
Alginatos/química , Emulsiones/química , Sustitutos de Grasa/química , Geles/química , Mananos/química , Sustancias Viscoelásticas/química , Animales , Pollos , Yema de Huevo/química , Emulsiones/síntesis química , Sustitutos de Grasa/síntesis química , Geles/síntesis química , Aceite de Brassica napus/química , Reología , Sustancias Viscoelásticas/síntesis química , Viscosidad
12.
ChemSusChem ; 13(4): 693-697, 2020 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-31821717

RESUMEN

The conversion of biomass-based platform molecules into various high-value chemicals greatly promotes the utilization of renewable biomass resources. Herein, an example of Rh-catalyzed ß-arylation of levulinic-acid-derived α-angelica lactone was reported, providing the γ-lactone-structure products with high regioselectivity. Both arylboronic and alkenylboronic acids could be applied in this transformation. This reaction tolerated a variety of synthetically important functional groups. Moreover, the obtained γ-lactone products could be readily converted to high-value products such as 1,4-diols and γ-methoxy-carboxylates.

13.
Sci Rep ; 9(1): 19547, 2019 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-31862938

RESUMEN

The aim of this study was to evaluate the effectiveness of preventing mother to child syphilis transmission to improve pregnancy outcomes. We performed a retrospective analysis of municipal databases of mother-to-child syphilis transmission. Pregnant women with syphilis were included. Group specific pregnancy outcomes were analyzed according to treatment. A total of 28 pregnant women were diagnosed with syphilis in 2012; 321 were diagnosed with syphilis in 2018. A prevalence of 0.14% was observed amongst pregnant women in Suzhou city from 2012-2018. Primary treatments included benzathine penicillin, ceftriaxone sodium or erythromycin when patients were allergic to Benzathine penicillin. The treatment coverage was 81.57%, and only 52.86% of pregnant women were adequately treated. Adverse pregnant outcomes were higher amongst untreated women. Expanding early screening coverage and promoting treatment were key to improving pregnancy outcomes amongst women with syphilis.


Asunto(s)
Transmisión Vertical de Enfermedad Infecciosa/prevención & control , Sífilis/prevención & control , Sífilis/transmisión , Adulto , Antibacterianos/uso terapéutico , Ceftriaxona/uso terapéutico , Eritromicina/uso terapéutico , Femenino , Humanos , Persona de Mediana Edad , Penicilina G Benzatina/uso terapéutico , Embarazo , Complicaciones Infecciosas del Embarazo/prevención & control , Resultado del Embarazo , Atención Prenatal , Estudios Retrospectivos , Adulto Joven
14.
Huan Jing Ke Xue ; 40(12): 5465-5472, 2019 Dec 08.
Artículo en Chino | MEDLINE | ID: mdl-31854619

RESUMEN

The dewaterability of excess sludge directly affects the efficiency and cost of sludge disposal, and improving sludge dewaterability is a crucial way to reduce sludge volume. This study proposes a method to improve the dewaterability of residual sludge by using mixed yeast strains to degrade extracellular polymeric substances (EPS) in activated sludge. Firstly, the mixed cells of three yeast strains were injected into the sterilized EPS solution to investigate the degradation efficiency of EPS components. Secondly, the mixed yeast cells were supplied into the residual sludge, which was aerated for several hours while the sludge dewaterability was evaluated. The results showed that the degradation efficiencies of yeast to proteins, polysaccharides, and nucleic acids in EPS were evident, and reductions of (60.43±2.73)%, (18.94±2.39)%, and (48.30±3.37)% were achieved, respectively, within 72 hours' oscillating cultivation. The capillary suction time (CST) of the sludge decreased by (17.19±1.16)% after aeration, with 1.5 g mixed yeast wet cells added into 2 L excess sludge, (7.03±1.35)% more than that of the control test after 24 hours. Meanwhile, the total amount of EPS in sludge decreased by (17.46±3.91)% more than that in the control sludge, indicating that the yeast can improve the sludge dewaterability in-situ by degrading EPS in sludge.


Asunto(s)
Aguas del Alcantarillado , Eliminación de Residuos Líquidos , Matriz Extracelular de Sustancias Poliméricas , Polisacáridos , Agua
15.
Carbohydr Polym ; 226: 115278, 2019 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-31582087

RESUMEN

In the study, a facile methodology for fabricating high viscoelastic emulsion gels has been proposed, which is based on the synergistic gelation mechanism of xanthan and konjac glucomannan (KGM). The effects of preparation strategies, oil contents and simulated sterilization conditions (121 °C, 30 min) on the emulsion gels were systemically investigated. All emulsion gels exhibited similar gelation temperature (Tgel) and gel melting temperature (Tmelt), indicating that the gelling continuous phase played a predominant role in the emulsion gel formation. However, the viscoelasticity of the emulsion gels was different depending on preparation strategies and oil phase fractions. When a low concentration of tween-80 (<1.0 %, v/v) was incorporated during emulsification process, the resultant emulsion gels showed satisfactory thermal stability and could undergo simulated sterilization conditions without discernible oil droplet coalescence observed. Conclusively, these results demonstrate the potentials of co-utilization of xanthan and KGM in designing novel food products.

16.
Biochem Biophys Res Commun ; 516(4): 1175-1182, 2019 09 03.
Artículo en Inglés | MEDLINE | ID: mdl-31296384

RESUMEN

The thinned-young apple polysaccharides from three varieties were obtained by hot water extraction at 88 ̊C for 120 min. The compositional monosaccharides of the three polysaccharides were shown to be the same (xylose, mannose, galactose and glucose) and the molecular weights of the polysaccharides were in the range of 200-300 kDa. Compared with "Qinyang" and "Pinklady", the polysaccharide from "Jinshiji" had the highest emulsifying capacity. Moreover, the variations in pH and cation ion concentrations had also a significant effect on the emulsifying properties of the extracted polysaccharides. At pH 2.0-4.0, the prepared emulsion had smaller droplet sizes than at higher pH values. Although the emulsion was stable at low concentrations of Na+ and Ca2+ ions, high concentrations of Na+ and Ca2+ led to significant destabilization of the emulsion. Conclusively, our results demonstrated the potential application of thinned-young apple polysaccharide as a natural polysaccharide emulsifying agent.


Asunto(s)
Emulsionantes/química , Malus/química , Polisacáridos/química , Calcio/química , Cationes/química , Emulsiones/química , Concentración de Iones de Hidrógeno , Monosacáridos/química , Sodio/química , Viscosidad
17.
Org Lett ; 21(14): 5645-5649, 2019 07 19.
Artículo en Inglés | MEDLINE | ID: mdl-31287696

RESUMEN

A palladium-catalyzed cross-coupling of gem-difluorinated cyclopropanes with boronic acids, providing the corresponding arylated/alkenylated/alkylated 2-fluoroallylic scaffolds, is generated. This new approach has good functional group compatibility for both gem-difluorinated cyclopropanes and boronic acids; thus, an array of synthetic building blocks of monofluoroalkene scaffolds including conjugated fluorodiene and skipped fluorodiene gave good yields with high Z-selectivity. Moreover, proficient application was described for monofluoroalkene, whereas the corresponding alkyl fluoride was constructed through hydrogenation.

18.
Nanoscale ; 11(26): 12413-12435, 2019 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-31231746

RESUMEN

With the explosion of data in the information universe and the approaching of fundamental limits in silicon-based flash memories, the exploration of new device architectures and alternative materials is necessary for next-generation memory technology. Accordingly, emerging two-dimensional (2D) material-based memristive devices have attracted increasing attention due to their unique properties and great potential in flexible and wearable devices, and even neuromorphic computing systems. Herein, we provide an overview of the recent progress on memristive devices based on 2D materials beyond graphene. The device structures and choice of active materials and electrodes materials are summarized for various types of 2D material-based memristive devices. Following the discussion and classification on the device performances and mechanisms, the challenges and perspectives on future research based on 2D materials are also presented.

19.
Intervirology ; 62(1): 30-36, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31117098

RESUMEN

BACKGROUND: Human adenoviruses (HAdV) are a common cause of viral conjunctivitis, making surveillance of them from sporadic cases of conjunctivitis important. METHODS: To acquire a better understanding of the epidemic genotypes of HAdV in outpatient children with adenoviral conjunctivitis in Jiangxi Province, China (2011-2012), 179 samples from cases with a high suspicion of HAdV were analyzed by PCR. Samples confirmed to be HAdV-positive by PCR were cultured in Hep-2 cells to isolate the viruses, which were then identified through hexon gene sequencing. RESULTS: The adenoviral conjunctivitis positivity rate was 74.86% (134/179), from which 71.64% (96/134) were infections in boys, and 92.54% (124/134) were infections in children under 5 years of age. Sixty-nine HAdV strains were isolated from the positive samples and 69 sequences were obtained. Phylogenetic analysis indicated that 33 strains (47.82%) clustered with HAdV-B7, 21 (30.43%) with HAdV-B3, 6 (8.70%) with HAdV-B55, 6 (8.70%) with HAdV-E4, 1 with HAdV-B21 (1.45%), 1 with HAdV-D37 (1.45%), and 1 with HAdV-D64 (1.45%). CONCLUSIONS: This is the first identification of HAdV-B55 relating to adenoviral conjunctivitis in China. These findings provide a firm basis for future surveillance of adenoviral conjunctivitis in China or other East Asian regions.


Asunto(s)
Infecciones por Adenovirus Humanos/epidemiología , Adenovirus Humanos/genética , Conjuntivitis Viral/epidemiología , Niño , Preescolar , China/epidemiología , Conjuntiva/virología , ADN Viral/genética , Femenino , Genotipo , Humanos , Lactante , Masculino , Pacientes Ambulatorios , Filogenia
20.
Int J Biol Macromol ; 134: 547-556, 2019 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-31100393

RESUMEN

In this study, a series of hydrogels based on the physical adsorption between hydroxyethyl cellulose (HEC) and colloidal silica nanoparticles (SNPs) were developed, and the effects of SNPs addition on the prepared gels were also investigated. The addition of SNPs into the HEC solution (1.0 wt%) induced gelation, and the gel strength was enhanced by increasing the SNPs concentration from 5 to 20 wt%, which was due to the formation of a denser gel network, as evidenced by SEM observations. Rheological tests suggested that the gelation temperature (Tg) was decreased with the increasing SNPs addition, and the gels exhibited slightly thermal hysteresis, with a temperature lag of 6-7 °C. However, when the SNPs concentration was above 21 wt%, a phase separation was observed. Furthermore, it was found that the addition of SNPs led to the intensified hydrogen bonds between the HEC molecules and the added SNPs, which may be the predominant factor governing the adsorption process. Overall, a facile method for hydrogel preparation was proposed in this study, and the gel properties were also systematically investigated. These results may provide useful information to the field of material science.


Asunto(s)
Celulosa/análogos & derivados , Coloides/química , Nanopartículas/química , Dióxido de Silicio/química , Celulosa/química , Fenómenos Químicos , Hidrogeles/química , Nanopartículas/ultraestructura , Reología , Análisis Espectral
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