► The effects of ultrasound on the molecular weight, structure and rheological properties of apple pectin were investigated. ► The degradation products had a uniform and narrow distribution of ...molecular weight. ► Degradation kinetics model of apple pectin fitted to 1/Mt−1/M0=kt from 5 to 45°C. ► Ultrasound treatment could not alter the primary structure properties of apple pectin. ► The viscosity of apple pectin decreased after ultrasound treatment.
The effects of ultrasound on the molecular weight of apple pectin were investigated. The structure and rheological properties of the degradation products were also tentatively identified by High Performance Liquid Chromatography–Photodiode Array Detector (HPLC–PAD), Infrared spectroscopy (IR), Nuclear Magnetic Resonance spectroscopy (NMR) and Rheometer. The results indicated that the weight-average molecular weight of apple pectin decreased obviously after ultrasound treatment. The molecular weight of degradation products had a uniform and narrow distribution. Ultrasound intensity and temperature play an important role in the degradation reaction. Degradation kinetics model of apple pectin fitted to 1/Mt−1/M0=kt from 5 to 45°C. The degree of methylation of apple pectin reduced according to IR analysis when ultrasound was applied. Ultrasound treatment could not alter the primary structure of apple pectin according to the results determined by HPLC, IR and NMR. Meanwhile, the viscosity of apple pectin was 103 times as large as that of ultrasound-treated apple pectin. The ultrasound-treated apple pectin showed predominantly viscous responses (G′<G″) over the same frequency range. The results suggested that ultrasound provided a viable alternative method for the modification of pectin.
Perfluoroalkyl acids (PFAAs) are a group of emerging persistent organic pollutants (POPs), which have been ubiquitously detected in the environmental media. However, national scale investigations on ...their occurrence and distribution in drinking water are still insufficient. In this study, we detected the 17 priority PFAAs in drinking water from 79 cities of 31 provincial-level administrative regions throughout China, and investigated their occurrence and distribution. Additionally, we also analyzed the influencing factors on their profiles, such as the existence of industrial sources, socioeconomic factors (population density and GDP), and assessed levels of risk associated with contaminated drinking water. On the national scale, the sum concentrations of the 17 PFAAs (∑17PFAAs) in drinking water was in a range of 4.49–174.93 ng/L with a mean value of 35.13 ng/L. Among the 17 individual PFAAs, perfluorobutanoic acids (PFBA) was the most abundant individual PFAAs with the median concentration of 17.87 ng/L, followed by perfluorooctanoic acid (PFOA, 0.74 ng/L), perfluorononanoic acid (PFNA, 0.40 ng/L) and perfluorooctane sulfonic acid (PFOS, 0.25 ng/L). The geographic distribution characteristic of ∑17PFAAs in drinking water was in a descending order of Southwestern China (57.67 ng/L) > Eastern coastal China (32.85 ng/L) > Middle China (29.89 ng/L) > Northwestern China (28.49 ng/L) > Northeastern China (22.03 ng/L), and in general, the existence of the industrial sources could positively affect the contamination levels of PFAAs in drinking water. The pollution level of PFAAs in drinking water also varied among the three different city levels (medium-sized city > big city > town). In towns, the positive correlations were observed between the population density and the ∑17PFAAs (R2 = 0.45, p < 0.01), and the individual concentration of PFHxA, PFBS, and PFOA (p < 0.01). Moreover, besides PFAAs in Yunnan, Jiangsu, and Jiangxi, concentrations of related PFAAs in drinking water from 28 provinces were less than the suggested drinking water advisories. The relatively higher concentrations of PFAAs in Yunnan, Jiangsu, and Jiangxi suggest that further studies focusing on their sources and potential health risk to humans are needed.
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•The nationwide occurrence of PFAAs in drinking water of China was investigated.•PFBA, PFOA, and PFHxS were dominated components in drinking water.•PFAAs concentration in drinking water varied among different regions and city levels of China.•PFAAs in drinking water might not pose a serious risk in most sample sites.
The molecular mass and its distribution of citrus pectin degraded by different methods were investigated. The primary structure and nanostructure of the degraded products were also identified. The ...results indicated that acid (80 °C, 12 h), ultrasound-assisted acid (25 °C, 2.5 h) and ultrasound (25 °C, 1.5 h) degraded pectins had equivalent molecular mass. The molecular mass distribution of ultrasound-assisted acid and ultrasound degraded pectins were less polydisperse than that of acid degraded pectin. According to HPLC, IR and NMR analysis, the main chain of ultrasound degraded pectin could be preserved. By contrast, acid degraded pectin was completely free of neutral sugar-side chains. Furthermore, the esterification level of ultrasound-assisted acid and ultrasound degraded pectins was considerably lower than that of original pectin, whereas that of the acid degraded pectin was nearly equal to zero. AFM analysis indicated that the morphology of original pectin was different from that of degraded pectins. The length of linear chains of degraded pectins was shorter and density of branches was lower, compared with that of original pectin. The results indicated that the ultrasound degradation method has the advantage of being timesaving, milder and environment-friendly.
•The molecular mass and structure of degraded pectin with different methods were investigated.•The pectin degraded by acid, ultrasound-assisted acid and ultrasound with different time had equivalent molecular mass.•The main chain of degraded citrus pectins with different methods could be preserved.•Acid degraded pectin was completely free of neutral sugar-side chains.•The morphology of original pectin was different from that of degraded pectins by AFM analysis.
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•The occurrence state of PPI-HMP was different at pH 5.0, 7.0, and 9.0.•Droplet breakup model under ultrasound was employed to analyse emulsion properties.•Characteristics of ...emulsions stabilised by PPI-HMP at pH 7.0 and 9.0 differed from that at pH 5.0.•Formation mechanisms of pH-shifted PPI-HMP stabilised emulsion under ultrasound were different.
The effect of pH on the occurrence states of peanut protein isolate (PPI) and high methoxyl pectin (HMP), and droplet breakup model of the emulsions under ultrasound were studied. Particle size distribution and scanning electron microscopy results showed that PPI-HMP existed a soluble complex at pH 5.0, had no interaction at pH 7.0, and was co-soluble at pH 9.0. Droplet breakup model results revealed that the characteristics of emulsion stabilised by PPI-HMP treated at pH 5.0 was different from that at pH 7.0 and 9.0. The average diameter of the droplet well satisfied the model. According to rheological properties, interface tension, and microstructure, the formation mechanism and characteristics of emulsion stabilised by PPI-HMP treated at pH 5.0 was different from that at pH 7.0 and pH 9.0. The research provided a reference for constructing emulsions using pH-shifted PPI-HMP under ultrasound.
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•Ultrasound improved oil–water interface behavior of PP-HMP.•Ultrasound regulated PP-HMP could self-assembly to form core–shell structures.•Ultrasound strengthened the electrostatic ...interactions of PP and HMP.•Ultrasound improved the emulsion stability of PP-HMP.
This study investigated the effects of ultrasound on the self-assembly behavior of pea protein (PP)-high methoxyl pectin (HMP) complexes at pH 2.0 through transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and intrinsic fluorescence analysis. The emulsion stabilization mechanism of PP-HMP treated with ultrasound (PP-HMP-US) was also elucidated. The results indicated that ultrasound increased the emulsifying activity index (EAI) and emulsifying stability index (ESI) of PP-HMP. Moreover, PP-HMP-US-based emulsions formed small, dispersed oil drops, which were stable during storage. PP-HMP- and PP-HMP-US-based emulsions did not demonstrate any creaming. The TEM results revealed that ultrasound can regulate the self-assembly behavior of PP and HMP to form spherical particles with a core–shell structure. This structure possessed low turbidity, a small particle size, and high absolute zeta potential values. The FTIR and intrinsic fluorescence spectra demonstrated that ultrasound increased the α-helix and β-sheet contents and exposed the tryptophan groups to more hydrophilic environments. Ultrasound also promoted the PP-HMP self-assembly through electrostatic interaction and improved its oil–water interfacial behavior, as indicated by the EAI and ESI values of PP-HMP-US-based emulsions. The current results provide a reference for the development of an innovative emulsifier prepared by ultrasound-treated protein–pectin complexes at low pH.
Photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) is a facile and highly efficient access to precision polymers. Herein, a facile photocontrolled iodine-mediated ...green RDRP strategy was successfully established in water by using 2-iodo-2-methylpropionitrile (CP-I) as the initiator and water-soluble functional monomers including poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2-hydroxyethyl methacrylate (HEMA), and 2-hydroxypropyl methacrylate (HPMA) as the model monomers under blue-light-emitting diode (LED) irradiation at room temperature. Well-defined polymers (PPEGMA, PHEMA, PHPMA) with narrow polydispersities (1.09–1.21) were obtained, and amphiphilic block copolymers which can form nanospheres in situ in water (PPEGMA-b-poly(benzyl methacrylate) (PPEGMA-b-PBnMA) and PPEGMA-b-PHPMA) were prepared. To explore the role of water in our polymerization, control experiments were successfully carried out by using oil-soluble monomer methyl methacrylate (MMA) with the help of trace amounts of water. Notably, the green solventwaterhas an additionally positive effect in accelerating the polymerization and makes our polymerization system an environmentally friendly polymerization system. Therefore, this simple strategy conducted in the presence of water enables the green preparation of well-defined water-soluble or water-insoluble polymers and clean synthesis of amphiphilic copolymer nanoparticles in situ.
miR408 is highly conserved among different plant species and targets transcripts encoding copper-binding proteins. The function of miR408 in reproductive development remains largely unclear despite ...it being known to play important roles during vegetative development in Arabidopsis. Here, we show that transgenic Arabidopsis plants overexpressing
have altered morphology including significantly increased leaf area, petiole length, plant height, flower size, and silique length, resulting in enhanced biomass and seed yield. The increase in plant size was primarily due to cell expansion rather than cell proliferation, and was consistent with higher levels of myosin gene expression and gibberellic acid (GA) measured in transgenic plants. In addition, photosynthetic rate was significantly increased in the MIR408-overexpressing plants, as manifested by higher levels of chloroplastic copper content and plastocyanin (PC) expression. In contrast, overexpression of miR408-regulated targets,
and
, resulted in reduced biomass production and seed yield. RNA-sequencing revealed that genes involved in primary metabolism and stress response were preferentially enriched in the genes upregulated in
-overexpressing plants. These results indicate that miR408 plays an important role in regulating biomass and seed yield and that
may be a potential candidate gene involved in the domestication of agricultural crops.
Side‐chain liquid crystalline polymer (SCLCP) usually contains a simple and flexible homopolymer as main chain, while its effect on the self‐assembly behavior is often ignored. In this work, in order ...to increase the structural complexity and investigate the interaction between the main chain and mesogens, perfluorinated segments are introduced into the main chain using a photoinduced Step Transfer‐Addition & Radical‐Termination polymerization method, producing a novel series of SCLCPs containing 4‐methoxyphenyl benzoate mesogens, soft hydrocarbon spacers, and a strictly alternating perfluoroalkyl and alkyl backbone. By adjusting the length of spacers or perfluoroalkyl segments, several mesophases with complex chain packing structures are achieved. This design strategy that constructing highly ordered liquid crystalline (LC) structures from SCLCPs with precise chemical structure provides a facile way toward novel LC nanomaterials.
A series of side‐chain liquid crystalline copolymers with an alternating hydrocarbon and fluorocarbon main chain are synthesized by Step Transfer‐Addition & Radical‐Termination polymerization. Several novel and interesting liquid crystalline (LC) structures, including nematic, smectic, and a possible 3D tetragonal LC phase, are formed by these copolymers, revealing the essentiality of fluorocarbon segment, as well as main‐chain structure, in obtaining complex LC phases.
An iron(III) (FeCl3·6H2O) catalyst was found to be an active catalyst for initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) of methyl methacrylate ...(MMA), using triphenylphosphine (PPh3) as a ligand and azobis(isobutyronitrile) (AIBN) as a thermal radical initiator, and 1,4-(2-bromo-2-methylpropionato)benzene (BMPB2) as an ATRP initiator. Effects of reaction temperature, catalyst concentration and AIBN concentration on polymerization were investigated. These results showed that the catalyst was highly efficient for the ICAR ATRP of MMA. For example, even if the catalyst concentration decreased to 34 ppm, the polymerization with the molar ratio of MMA0/BMPB20/FeCl3·6H2O0/PPh30/AIBN0 = 500/1/0.03/1.5/0.1 could be carried out at 60 °C with a conversion 70.4% in 32 h. At the same time, the molecular weight of the obtained PMMA with a narrow molecular weight distribution (M w/M n = 1.37) was consistent with the theoretical one.
This paper reports a novel method to prepare PCL/PLGA/HA (w/w=6/4/2) bone tissue scaffold through melt-blending and particle-leaching. The ultrastructural and physicochemical properties of the ...scaffolds were studied by SEM, FTIR, XRD and TGA. Its porous rate and average size were 75.74±1.21% and 179.07±0.75μm, tensile strength and compressive strength were 147±5MPa and 47±2MPa. The 24-week degradation rate was 32.31±1.93%. Human mesenchymal stem cells were cultured in the scaffolds for 14–21days in vitro. The results indicate that scaffolds can promote hMSCs proliferation and osteogenesis by enhancing the expression of ALP. The expression of the bone-related genes Runx2, OPN, OCN, BMP-2, collagen I, integrin a1, integrin b1, and SLP was markedly upregulated, suggesting that this scaffold can promote hMSCs differentiation, proliferation and maturation to osteoblasts. In vivo experiments, the scaffolds were implanted in a rabbit skull-defect model. Micro X-ray 3D imaging, HE, and immunohistochemistry revealed that the scaffold materials are degradable and also display excellent biocompatibility, along with the capacity to induce bone regeneration. Therefore, PCL/PLGA/HA scaffold materials would be promising in the repair and regeneration of non-weight-bearing bones.
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•The biomaterial scaffold in the study was fabricated through melt-blending/particle-leaching process for the first time.•The scaffold material can promote the proliferation and differentiation of human mesenchymal stem cells.•The scaffold material might be a promising biomaterial in the bone regeneration engineering.
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