In this study,polysaccharides were extracted from blueberry fruit(BFP)and isolated to 3 components(BFP-1,BFP-2 and BFP-3).The molecular weight,monosaccharide composition,characteristic groups,microscopic morphology,an...In this study,polysaccharides were extracted from blueberry fruit(BFP)and isolated to 3 components(BFP-1,BFP-2 and BFP-3).The molecular weight,monosaccharide composition,characteristic groups,microscopic morphology,and triple helical conformation of the polysaccharides were characterized using high performance permeation chromatography,high performance liquid chromatography,gas chromatographymass spectrometry,Fourier transform infrared spectrometer,scanning electron microscope and Congo red staining.Moreover,the hypolipidemic and immunological activities of the polysaccharides were also assessed.Results showed that the molecular weights of polysaccharides BFP-1,BFP-2,and BFP-3 were 5.547×10^(4),5.671×10^(4),and 3.951×10^(4)Da,respectively,the main monosaccharides were glucose(Glc),galactose(Gal)and arabinose(Ara),but BFP-3 was mainly composed of galacturonic acid(Gal A),Glc,Gal,and Ara.The backbone of BFP-1 was→4)-Glcp-(1→,which branches to Ara and xylose(Xyl)residues,while the backbone of BFP-2 was→5)-Araf-(1→,which branches to Xyl,Glc,rhamnose(Rha)and Gal residues,in particularly,BFP-3 has a more complex branching with a→3,6)-Galp-(1→)backbone,the side chain is dominated by Araf-(1→).Blueberry polysaccharides are pyran-type polysaccharides withα-glycosidic bonds,and BFP-1 has a typical triple-helical structure.The activity assay revealed that the binding of BFP-3 to sodium glycylcholate hydrate and sodium taurocholate was 79.95%and 78.50%,respectively,indicating that it had better hypolipidemic activity than the others.Immunoactivity assay showed that BFP promoted NO secretion through activating the NF-κB signalling pathway in RAW264.7 cells,which played a role in enhancing the immune function of the organism.These findings may provide a reference for the development and application of blueberry polysaccharides in functional food and medicine.展开更多
Three novel acidic polysaccharide fractions(OFPP-1,OFPP-2,OFPP-3)with different m olecular weights(803.7,555.1 and 414.5 k Da)were isolated from the peeled Opuntia dillenii Haw.fruits by alkali-extraction,graded alcoh...Three novel acidic polysaccharide fractions(OFPP-1,OFPP-2,OFPP-3)with different m olecular weights(803.7,555.1 and 414.5 k Da)were isolated from the peeled Opuntia dillenii Haw.fruits by alkali-extraction,graded alcohol precipitation and column chromatography.Structural analysis indicated that OFPPs were pectic polysaccharides consisting of rhamnose,arabinose and galactose residues.The backbone of OFPP-1 consisted of a repeating unit→6-α-D-Galp A-(1→2)-α-L-Rhap-(1→with T-α-D-Galp A-(1→6)-α-D-Galp A-(1→4)-α-D-Glcp-(1→,T-β-D-Xylp-(1→6)-α-D-Galp A-(1→4)-α-D-Glcp-(1→or T-α-D-Galp A-(1→3)-α-L-Araf-(1→as the side chains.The backbone of OFPP-2 consisted of a disaccharide repeating unit→2)-α-L-Rhap-(1→4)-β-D-Galp A-(1→with T-β-L-Araf-(1→as the branches substituted at the O-4 position of→2,4)-α-LRhap-(1→.Whereas the backbone of OFPP-3 was→2,4)-α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-β-L-Araf-(1→or→2,4)-α-L-Rhap-(1→2)-α-L-Rhap-(1→4)-β-D-Galp A-(1→,which was branched at the O-4 position of→2,4)-α-L-Rhap-(1→.Moreover,these three polysaccharide fractions could protect Huh-7 cells against H2O2-induced oxidative stress to different extents by decreasing the MDA content and increasing the SOD,CAT,GSH-Px activities and the GSH level in the Huh-7 cells.These results suggest that OFPPs have the potential to be used as natural antioxidants.展开更多
Natural polysaccharides named PEP-0.1-1,PEP-0-1 and PEP-0-2 from edible mushroom species Pleurotus eryngii were obtained in the present study.Results showed that molecular weights of these polysaccharides were 3235,20...Natural polysaccharides named PEP-0.1-1,PEP-0-1 and PEP-0-2 from edible mushroom species Pleurotus eryngii were obtained in the present study.Results showed that molecular weights of these polysaccharides were 3235,2041 and 23933 Da,respectively.Further,structural characterization revealed that PEP-0.1-1 had a→4-α-D-Glcp-1→backbone and contained→4)-α-D-Glcp and→4)-β-D-Glcp reducing end groups.PEP-0-1 backbone contained→4-α-D-Glcp-1→and→6-α-3-O-Me-D-Galp-1→,and the side chains containedα-D-Glcp,β-D-Manp-1→andα-D-Glcp-3→.However,PEP-0-2 backbone consisted of→4-α-DGlcp-1→and→6-α-3-O-Me-D-Galp-(1→6)-α-D-Galp-1→while the side chains containedα-D-Glcp andβ-D-Manp-1→.Biological activity analysis was then carried out and found that all these polysaccharides could significantly suppress the relative mRNA expression of toll-like receptor 4,nitric oxide(NO),tumor necrosis factor-α,interleukin(IL)-1βand IL-6 in lipopolysaccharide(LPS)-induced inflammation of RAW264.7 cells,as well as the over secretion of the above cell cytokines.Moreover,Western blotting analysis revealed that all these purified fractions displayed significant inhibition effects on the expression of c-Jun N-terminal kinases protein induced by LPS in mitogen activated protein kinase pathway,along with the relieving on the inhibition effect of LPS on IκB-αprotein expression.In summary,the information generated by the present study could provide a theoretical basis for the exploration of novel healthy food materials from edible mushroom with antiinflammation activities.展开更多
A water-soluble polysaccharide from abalone muscle(AMPP)was isolated.The contents of carbohydrate,protein,uronic acid,and sulfate in AMPP were 83.5%,0.5%,2.7%,and 2.6%,respectively.High-performance liquid chromatograp...A water-soluble polysaccharide from abalone muscle(AMPP)was isolated.The contents of carbohydrate,protein,uronic acid,and sulfate in AMPP were 83.5%,0.5%,2.7%,and 2.6%,respectively.High-performance liquid chromatography analysis indicated that AMPP was homogeneous and had an average molecular weight of approximately 3.2 kDa.The main monosaccharides of AMPP were glucose(Glc)and mannose with a molar ratio of 99.7:0.3.The structural characteristics of AMPP were elucidated through methylation analysis,Fourier transform infrared spectroscopy,and nuclear magnetic resonance spectroscopy.The linkages of AMPP consisted of terminal,1,4-linked,1,6-linked,and 1,4,6-linked Glcp with a molar ratio of 3.1:7.2:1.0:2.5.In one repeat unit of the proposed AMPP structure,the backbone chain was composed of eight 1→4 glycosidic bonds and one 1→6 glycosidic bond,with three branch chains linked by 1→6 glycosidic bond.In addition,AMPP was found to possess potent immunostimulatory activity via rising phagocytosis of RAW264.7 cells and promoting secretion of TNF-α.展开更多
In this study,chondroitin sulfate was extracted from Oreochromis niloticus bones(OCS)and isolated to three fractions(OCS-1,OCS-2,and OCS-3).The physicochemical properties and structure characterization including monos...In this study,chondroitin sulfate was extracted from Oreochromis niloticus bones(OCS)and isolated to three fractions(OCS-1,OCS-2,and OCS-3).The physicochemical properties and structure characterization including monosaccharide,disaccharide compositions,molecular weight(Mw)of OCS were determined by HPAEC,HPLC-SAX,HPGPC,FT-IR spectra,and 1D/2D NMR.Moreover,their thermal properties,crystalline structure,and microstructure were also analyzed.Results showed that their Mw were between 10 kDa and 50 kDa.CS-6 was the predominant disaccharide unit in four OCS,and the CS-4/CS-6 ratios were close to CS from shark cartilage.Besides,the results of antioxidant activity showed that different fractions of OCS had a distinct DPPH radical,hydroxyl radical,and ABTS+radical scavenging activity.OCS-1 has the highest scavenging activities in DPPH and hydroxyl radical compared with other fractions,which showed a higher medicinal value.Those findings may lay some theoretical basis for the potential application development of OCS.展开更多
Sea buckthorn(Hippophae rhamnoides L.)is a natural homologous substance of medicine and food.Polysaccharide,as one of its primary active components,has very superior biological activity and can be used as a dietary su...Sea buckthorn(Hippophae rhamnoides L.)is a natural homologous substance of medicine and food.Polysaccharide,as one of its primary active components,has very superior biological activity and can be used as a dietary supplement for functional foods,with good commercial prospects.Although initial progress has been made in the study of sea buckthorn polysaccharides,related studies have been fragmented and lacked systematic and generalization.This manuscript presents a critical analysis and systematic summary of the extraction and purification methods,structural characterization and physicochemical properties,biological activity and potential mechanisms,and structure-activity relationships of sea buckthorn polysaccharides.Accumulating evidence has indicated that sea buckthorn polysaccharides,which were widely prepared by water extraction and column chromatography purifications,exhibited exhibit superior biological activities in vitro and in vivo,including antioxidant,immunomodulatory,anti-inflammatory,hepatorenal protective,antibacterial,antiviral,and prebiotic activities.After analysis,it was concluded that there is a correlation between the relevant activities of sea buckthorn polysaccharides and that the structure of sea buckthorn polysaccharides has a great influence on their biological activity.We reviewed the challenges and limitations of sea buckthorn polysaccharides,summarized the critical aspects,and provided suggestions for potential breakthroughs in the research and application of sea buckthorn polysaccharide.展开更多
Food allergens are mainly naturally-occurring proteins with immunoglobulin E(IgE)-binding epitopes.Understanding the structural and immunogenic characteristics of allergenic proteins is essential in assessing whether ...Food allergens are mainly naturally-occurring proteins with immunoglobulin E(IgE)-binding epitopes.Understanding the structural and immunogenic characteristics of allergenic proteins is essential in assessing whether and how food processing techniques reduce allergenicity.We here discuss the impacts of food processing technologies on the modification of physicochemical,structural,and immunogenic properties of allergenic proteins.Detection techniques for characterizing changes in these properties of food allergens are summarized.Food processing helps to reduce allergenicity by aggregating or denaturing proteins,which masks,modifies,or destroys antigenic epitopes,whereas,it cannot eliminate allergenicity completely,and sometimes even improves allergenicity by exposing new epitopes.Moreover,most food processing techniques have been tested on purified food allergens rather than food products due to potential interference of other food components.We provide guidance for further development of processing operations that can decrease the allergenicity of allergenic food proteins without negatively impacting the nutritional profile.展开更多
Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the meth...Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the methods in defect controlcurrently face challenges with overly large operational areas and a lack of precision in targeting specific defects. Therefore,we propose a new method for the precise and universal defect healing of TMD materials, integrating real-time imaging withscanning transmission electron microscopy (STEM). This method employs electron beam irradiation to stimulate the diffusionmigration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy (MBE),and heal defects within the diffusion range. This approach covers defect repairs ranging from zero-dimensional vacancydefects to two-dimensional grain orientation alignment, demonstrating its universality in terms of the types of samples anddefects. These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEMfor defect healing, providing valuable experience for achieving atomic-level precise fabrication of TMD materials.展开更多
In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X...In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM).We analyzed their lipidlowering properties in vitro(water holding,oil holding swelling cholesterol and sodium cholate binding capacitises)and the hypolipidemic effects in mice.The results showed that tremella dietary fibers presented the infrared absorption spectrum characteristics of polysaccharides and the characteristic diffraction peaks of cellulose type I.SEM results indicated that the surface of insoluble dietary fiber(IDF)was porous,while the soluble dietary fiber(SDF)was relatively compact and spongy.IDF exhibited significantly higher water holding,oil holding,and swelling binding capacities than the corresponding SDF.However,SDF exhibited significantly higher viscosity than IDF.The results showed tremella dietary fibers were significant in swelling,water holding and oil holding,cholesterol and bile acids.In vivo experiment results in mice indicated that SDF has the best effect on hyperlipidemia mice than IDF and total dietary fiber(TDF).SDF showed that the total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)contents dropped by 28.33%,18.65%,and 48.97%,respectively,while high density lipoprotein cholesterol(HDL-C)content increased by 43.80%.Compared with the high-fat control(HCM)group,the arteriosclerosis index(AI)and liver index(LI)of the SDF group mice showed significant differences,indicating that SDF has a good auxiliary effect of lowering blood lipids.The administration of tremella fibers improved the lipid metabolism disorderly situation of hyperlipidemia mice.These results provide a reference for further research and rational development of T.fuciformis.展开更多
This study aimed to isolate and characterize the structures of glycoproteins from peas and determine their hypoglycemic activity.The crude pea glycoproteins(PGP)were extracted by hot water and purified by diethylamino...This study aimed to isolate and characterize the structures of glycoproteins from peas and determine their hypoglycemic activity.The crude pea glycoproteins(PGP)were extracted by hot water and purified by diethylaminoethyl(DEAE)-Sepharose chromatography and Sephadex G-100 size-exclusion chromatography in sequence.Then three main fractions were obtained,namely PGP1,PGP2 and PGP3,with molecular weights of 897615,846740 and 1194692 Da,respectively.The physical and chemical properties of the three fractions were evaluated and compared by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR),scanning electron microscope(SEM),high performance liquid chromatography(HPLC)and other analytical techniques.The fraction PGP2 with the highest hypoglycemic activity,was screened using the Caco-2 monolayer cell model.It can inhibit the uptake of glucose in the small intestine,as well as the activities of maltase and sucrase.After simulated gastrointestinal digestion,PGP2 signifi cantly enhanced the inhibitory effect of α-glucosidase,and slightly reduced the inhibitory ability ofα-amylase.In summary,PGP2 possessed strong hypoglycemic activity after digestion.These results indicated that PGP2 has the potential to be developed into a functional food or natural medicine for the treatment of type 2 diabetes mellitus.展开更多
The development of novel organic electrode materials is of great significance for improving the reversible capacity and cycle stability of rechargeable batteries.Before practical application,it is essential to charact...The development of novel organic electrode materials is of great significance for improving the reversible capacity and cycle stability of rechargeable batteries.Before practical application,it is essential to characterize the electrode materials to study their structures,redox mechanisms and electrochemical performances.In this review,the common characterization methods that have been adopted so far are summarized from two aspects:experimental characterization and theoretical calculation.The experimental characterization is introduced in detail from structural characterization,electrochemical characterization and electrode reaction chara cterization.The experimental purposes and working principles of various experimental characterization methods are briefly illustrated.As the auxilia ry means,theoretical calculation provides the theoretical basis for characterizing the electrochemical reaction mechanism of organic electrode materials.Through these characterizations,we will have a deep understanding about the material structures,electrochemical redox mechanisms,electrochemical properties and the relationships of structure-property.It is hoped that this review would help researchers to select the suitable characterization methods to analyze the structures and performances of organic electrode materials quickly and effectively.展开更多
Allium cepa L.var.agrogatum Don(ALAP)is commonly consumed in China as well as other regions and has various beneficial health effects.A novel acidic polysaccharide(named ALAP-21)was obtained from ALAP by ultrasonic an...Allium cepa L.var.agrogatum Don(ALAP)is commonly consumed in China as well as other regions and has various beneficial health effects.A novel acidic polysaccharide(named ALAP-21)was obtained from ALAP by ultrasonic and microwave-assisted extraction and purification using DEAE-52 anion exchange and Sephadex G-100 columns.The monosaccharide composition,structural and antioxidative properties of ALAP-21 were investigated by GC–MS chromatography,FT-IR and NMR spectroscopies and three antioxidative activity tests in vitro.The results showed that ALAP-21 was a heteropolysaccharide composed of glucose,galacturonic acid,mannose,galactose,arabinose,rhamnose,xylose,fructose and glucuronic acid with a relative molar ratio of 26.282:27.546:11.400:4.781:2.467:2.445:3.622:1.106:1.753,owning(1→4)-β-d-Glcp,(1→4)-β-d-GalAp6Me3OA,(1→4)-β-d-Galp6OMe,(1→2)-β-l-Rhap,(1→4)-β-d-Manp glycosidic linkages.(1→4)-β-d-Glcp and(1→4)-β-d-GalAp6Me3OA residues might be the main components of the sugar chain backbone of ALAP-21.Furthermore,ALAP-21 exhibited high potential for DPPH radicals(82.02%),hydroxyl radicals(53.33%)and superoxide anion radicals(50.28%).These results provide a reference for further research and rational development of ALAP polysaccharides.展开更多
Coal chemical wastewater(CCW)with the features of high toxicity and poor biodegradability is a big issue in environmental remediation,posing a great threat to aquatic ecosystems and to human beings.Such complex molecu...Coal chemical wastewater(CCW)with the features of high toxicity and poor biodegradability is a big issue in environmental remediation,posing a great threat to aquatic ecosystems and to human beings.Such complex molecular mixtures are notoriously difficult to characterize without initial physical separation.Herein,we present the 3D diffusion ordered spectroscopy(DOSY)analysis for CCW using DOSY-COSY and DOSY-HSQC methods,the advantages of this strategy have been demonstrated in the analysis of mixtures of aliphatic oxygenates and aromatic compounds,before being implemented on a genuine CCW sample in this study.The results showed that 3D DOSY is a robust and reliable tool for providing superior resolution and virtual separation of complex pollutants,and can be used as a general approach for structural elucidation.展开更多
Anatase TiO_(2)nanospindles containing 89%exposed{101}facets(TIO_(2)-101)and nanosheets with 77%exposed{001}facets(TiO_(2)-001)were hydrothermally synthesized and used as supports for Pd catalysts.The effects of the T...Anatase TiO_(2)nanospindles containing 89%exposed{101}facets(TIO_(2)-101)and nanosheets with 77%exposed{001}facets(TiO_(2)-001)were hydrothermally synthesized and used as supports for Pd catalysts.The effects of the TiO_(2)materials on the catalytic performance of Pd/TiO_(2)-101 and Pd/TiO_(2)-001 catalysts were investigated in the selective hydrogenation of acetylene to polymer-grade ethylene.The PdfTiO_(2)-101 catalyst exhibited enhanced performance in terms of acetylene conversion and ethylene yield.To understand these effects,the catalysts were characterized by H_(2)temperature-programmed desorption(H_(2)-TPD),H_(2)temperature-programmed reduction(H=-TPR),transmission electron microscopy(TEM),pulse CO chemisorption,X-ray photoelectron spectroscopy(XPS),and thermogravimetric analysis(TGA).The TEM and CO chemisorption results confirmed that Pd nanoparticles(NPs)on the TiO_(2)-101 support had a smaller average particle size(1.53 nm)and a higher dispersion(15.95%)than those on the TiO_(2)-001 support(average particle size of 4.36 nm and dispersion of 9.06%).The smaller particle size and higher dispersion of Pd on the Pd/TiO_(2)-101 catalyst provided more reaction active sites,which contributed to the improved catalytic activity of this supported catalyst.展开更多
A mass of nanoparticles/nanorods were formed on a simultaneously deposited gran- ular film by plasma enhanced chemical vapor deposition （PECVD） of perfluorohexane at atmo- spheric pressure without any catalysts or t...A mass of nanoparticles/nanorods were formed on a simultaneously deposited gran- ular film by plasma enhanced chemical vapor deposition （PECVD） of perfluorohexane at atmo- spheric pressure without any catalysts or templates. Scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS） were used to characterize the morphology and the chem- ical compositions of nanoparticles. The average size of particles is about 100 nm and the length of synthesized nanorods is between 1 μm and 2.5/tm. The analyses of transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HRTEM）, selected area electron diffraction（SAED） and X-ray diffraction （XRD） reveals that the nanoparticles and nanorods are crystalline.展开更多
For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To...For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.展开更多
The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended v...The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging to obtain photocatalyst with absorption edge of above 550 nm.Here we report a novel Sn^(2+)-based oxyfluoride Sn_(2)TiNbO_6 F(STNOF)photocatalyst with a pyrochlore structure to exhibit an extended absorption edge to 650 nm and dual functionalities of both water reduction and oxidation.Density functional theory calculations suggest that the unprecedented broad-spectrum response of STNOF is mainly ascribed to the strengthened hybridization between O 2 p and Sn 5 s orbitals remarkably upshifting the valence band,which is caused by the distortion and compressive strain in the Sn06 F2 dodecahedron with second-order Jahn-Teller effect due to partial fluorine substitution.The structural distortion and compressive strain are experimentally confirmed by the Fourier-transformed extended X-ray absorption fine spectra.As probe tests of the photocatalytic functionalities,water reduction and oxidation half reactions were examined to see obvious H_(2)and O_(2)evolution under visible light irradiation.This work may provide an alternative strategy of developing extended visible light responsive semiconductors for promising solar energy conversion.展开更多
Using transmission electron microscopy （TEM） and x-ray diffraction analysis, we have studied the structural and morphological evolution of highly Er/Yb co-doped A1203 films in the temperature range from 600℃-900℃....Using transmission electron microscopy （TEM） and x-ray diffraction analysis, we have studied the structural and morphological evolution of highly Er/Yb co-doped A1203 films in the temperature range from 600℃-900℃. By comparison with TEM observation, the annealing behaviours of photoluminescence （PL） emission and optical loss were found to have relation to the structure and morphology. The increase of PL intensity and optical loss above 800℃ might result from the crystallization of amorphous Al2O3 films. Based on the study on the structure and morphology, a rate equation propagation model of a multilevel system was used to calculate the optical gains of Er-doped Al2O3 planar waveguide amplifiers involving the variation of PL efficiency and optical loss with annealing temperature. It was found that the amplifiers had an optimized optical gain at the temperature corresponding to the minimum of optical loss, rather than at the temperature corresponding to the maximum of PL efficiency, suggesting that the optical loss is a key factor for determining the optical gain of an Er-doped Al2O3 planar waveguide amplifier.展开更多
Tremella fuciformis polysaccharide(TFP) is an important bioactive substance in T. fuciformis, which contributes to its application as medicine and food. In the present work, TFP was extracted with enzymatic combined w...Tremella fuciformis polysaccharide(TFP) is an important bioactive substance in T. fuciformis, which contributes to its application as medicine and food. In the present work, TFP was extracted with enzymatic combined with wet beating and its physicochemical as well as biological activities were investigated in the study. The result showed that the purity of TFP1 reached 92.14%(m/m). The TFP1, purified by DEAE column, had a molecular weight(Mw) of 5.8 × 10^(3) k Da and consisted mainly of mannose, xylose, fucose, glucose and glucuronic acid at a molar ratio of 1.91 : 0.1 : 2.49 : 6.23 : 0.95. The structure of TFP1 was preliminarily investigated by infrared spectroscopy, nuclear magnetic resonance and atomic force microscope(AFM) analysis. Moreover, the antioxidant assays showed that TFP1 could scavenge DPPH, ABTS+ and hydroxyl radicals. The excellent water holding capacity of TFP1 implied its application in the food, pharmaceutical andcosmetic industries.展开更多
This study was to investigate the structure and rat fecal microbial fermentation properties of a polysaccharide fraction(PHP2)isolated from the red marine alga Porphyra haitanensis.PHP2 was characterized as a sulfated...This study was to investigate the structure and rat fecal microbial fermentation properties of a polysaccharide fraction(PHP2)isolated from the red marine alga Porphyra haitanensis.PHP2 was characterized as a sulfated glucogalactan,with a hypothetical backbone structure of→4)Gα(1→6)G4 Sβ(1→4)Glc(1→and a side chain of Man(1→6)Glc.PHP2 had an irregular spherical chain conformation.The 16 S r RNA sequence analysis revealed that PHP2 modulated the rat fecal micro-flora composition,with a similar effect to inulin,changing the dominant genus(Lactobacillus and Escherichia-Shigella)and promoting the growth of organisms that degrade sulfur-containing polysaccharides,such as Desulfovibrio,Ruminococcaceae_UCG-005,and Ruminococcus_2.PHP2 can promote production of acetic,propionic and butyric acid by rat fecal micro-flora.Prediction of metabolic function suggested that PHP2 could modulate cholesterol metabolism.The sulfated glucogalactan fermentation behavior may be associated with its monosaccharide composition,chain branching and chain conformation.PHP2 appeared to have considerable potential as functional food,and was associated with sulfur-containing polysaccharides in general.展开更多
基金financial support received from the Anhui Provincial Excellent Scientific Research and Innovation Team(2023AH010050)the Key Research and Development Plan of Anhui Province(202204c06020013,202204c06020029)+1 种基金the“Biology and Medicine”key subject of Hefei University(2023xk05)the open research project of Anhui Ecological Fermentation Engineering Research Center for Functional Fruit Beverage(FSKFKT015)。
文摘In this study,polysaccharides were extracted from blueberry fruit(BFP)and isolated to 3 components(BFP-1,BFP-2 and BFP-3).The molecular weight,monosaccharide composition,characteristic groups,microscopic morphology,and triple helical conformation of the polysaccharides were characterized using high performance permeation chromatography,high performance liquid chromatography,gas chromatographymass spectrometry,Fourier transform infrared spectrometer,scanning electron microscope and Congo red staining.Moreover,the hypolipidemic and immunological activities of the polysaccharides were also assessed.Results showed that the molecular weights of polysaccharides BFP-1,BFP-2,and BFP-3 were 5.547×10^(4),5.671×10^(4),and 3.951×10^(4)Da,respectively,the main monosaccharides were glucose(Glc),galactose(Gal)and arabinose(Ara),but BFP-3 was mainly composed of galacturonic acid(Gal A),Glc,Gal,and Ara.The backbone of BFP-1 was→4)-Glcp-(1→,which branches to Ara and xylose(Xyl)residues,while the backbone of BFP-2 was→5)-Araf-(1→,which branches to Xyl,Glc,rhamnose(Rha)and Gal residues,in particularly,BFP-3 has a more complex branching with a→3,6)-Galp-(1→)backbone,the side chain is dominated by Araf-(1→).Blueberry polysaccharides are pyran-type polysaccharides withα-glycosidic bonds,and BFP-1 has a typical triple-helical structure.The activity assay revealed that the binding of BFP-3 to sodium glycylcholate hydrate and sodium taurocholate was 79.95%and 78.50%,respectively,indicating that it had better hypolipidemic activity than the others.Immunoactivity assay showed that BFP promoted NO secretion through activating the NF-κB signalling pathway in RAW264.7 cells,which played a role in enhancing the immune function of the organism.These findings may provide a reference for the development and application of blueberry polysaccharides in functional food and medicine.
基金supported by the National Natural Science Foundation of China(No.31972977)。
文摘Three novel acidic polysaccharide fractions(OFPP-1,OFPP-2,OFPP-3)with different m olecular weights(803.7,555.1 and 414.5 k Da)were isolated from the peeled Opuntia dillenii Haw.fruits by alkali-extraction,graded alcohol precipitation and column chromatography.Structural analysis indicated that OFPPs were pectic polysaccharides consisting of rhamnose,arabinose and galactose residues.The backbone of OFPP-1 consisted of a repeating unit→6-α-D-Galp A-(1→2)-α-L-Rhap-(1→with T-α-D-Galp A-(1→6)-α-D-Galp A-(1→4)-α-D-Glcp-(1→,T-β-D-Xylp-(1→6)-α-D-Galp A-(1→4)-α-D-Glcp-(1→or T-α-D-Galp A-(1→3)-α-L-Araf-(1→as the side chains.The backbone of OFPP-2 consisted of a disaccharide repeating unit→2)-α-L-Rhap-(1→4)-β-D-Galp A-(1→with T-β-L-Araf-(1→as the branches substituted at the O-4 position of→2,4)-α-LRhap-(1→.Whereas the backbone of OFPP-3 was→2,4)-α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-β-L-Araf-(1→or→2,4)-α-L-Rhap-(1→2)-α-L-Rhap-(1→4)-β-D-Galp A-(1→,which was branched at the O-4 position of→2,4)-α-L-Rhap-(1→.Moreover,these three polysaccharide fractions could protect Huh-7 cells against H2O2-induced oxidative stress to different extents by decreasing the MDA content and increasing the SOD,CAT,GSH-Px activities and the GSH level in the Huh-7 cells.These results suggest that OFPPs have the potential to be used as natural antioxidants.
基金supported by the National Natural Science Foundation of China(31901623)Major Public Welfare Projects in Henan Province(201300110200)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Natural polysaccharides named PEP-0.1-1,PEP-0-1 and PEP-0-2 from edible mushroom species Pleurotus eryngii were obtained in the present study.Results showed that molecular weights of these polysaccharides were 3235,2041 and 23933 Da,respectively.Further,structural characterization revealed that PEP-0.1-1 had a→4-α-D-Glcp-1→backbone and contained→4)-α-D-Glcp and→4)-β-D-Glcp reducing end groups.PEP-0-1 backbone contained→4-α-D-Glcp-1→and→6-α-3-O-Me-D-Galp-1→,and the side chains containedα-D-Glcp,β-D-Manp-1→andα-D-Glcp-3→.However,PEP-0-2 backbone consisted of→4-α-DGlcp-1→and→6-α-3-O-Me-D-Galp-(1→6)-α-D-Galp-1→while the side chains containedα-D-Glcp andβ-D-Manp-1→.Biological activity analysis was then carried out and found that all these polysaccharides could significantly suppress the relative mRNA expression of toll-like receptor 4,nitric oxide(NO),tumor necrosis factor-α,interleukin(IL)-1βand IL-6 in lipopolysaccharide(LPS)-induced inflammation of RAW264.7 cells,as well as the over secretion of the above cell cytokines.Moreover,Western blotting analysis revealed that all these purified fractions displayed significant inhibition effects on the expression of c-Jun N-terminal kinases protein induced by LPS in mitogen activated protein kinase pathway,along with the relieving on the inhibition effect of LPS on IκB-αprotein expression.In summary,the information generated by the present study could provide a theoretical basis for the exploration of novel healthy food materials from edible mushroom with antiinflammation activities.
基金financial support received from the National Key R&D Program of China(2021YFD2100200/2021Y FD2100202)National Natural Science Fund(31571835),Fujian Key Project of Natural Science Foundation(2019J02013)the Opening Project of Fujian Provincial Engineering Technology Research Center of Marine Functional Food(Z820239)。
文摘A water-soluble polysaccharide from abalone muscle(AMPP)was isolated.The contents of carbohydrate,protein,uronic acid,and sulfate in AMPP were 83.5%,0.5%,2.7%,and 2.6%,respectively.High-performance liquid chromatography analysis indicated that AMPP was homogeneous and had an average molecular weight of approximately 3.2 kDa.The main monosaccharides of AMPP were glucose(Glc)and mannose with a molar ratio of 99.7:0.3.The structural characteristics of AMPP were elucidated through methylation analysis,Fourier transform infrared spectroscopy,and nuclear magnetic resonance spectroscopy.The linkages of AMPP consisted of terminal,1,4-linked,1,6-linked,and 1,4,6-linked Glcp with a molar ratio of 3.1:7.2:1.0:2.5.In one repeat unit of the proposed AMPP structure,the backbone chain was composed of eight 1→4 glycosidic bonds and one 1→6 glycosidic bond,with three branch chains linked by 1→6 glycosidic bond.In addition,AMPP was found to possess potent immunostimulatory activity via rising phagocytosis of RAW264.7 cells and promoting secretion of TNF-α.
基金The financially supported by the Program of The National Youth Talent Support Program of China.
文摘In this study,chondroitin sulfate was extracted from Oreochromis niloticus bones(OCS)and isolated to three fractions(OCS-1,OCS-2,and OCS-3).The physicochemical properties and structure characterization including monosaccharide,disaccharide compositions,molecular weight(Mw)of OCS were determined by HPAEC,HPLC-SAX,HPGPC,FT-IR spectra,and 1D/2D NMR.Moreover,their thermal properties,crystalline structure,and microstructure were also analyzed.Results showed that their Mw were between 10 kDa and 50 kDa.CS-6 was the predominant disaccharide unit in four OCS,and the CS-4/CS-6 ratios were close to CS from shark cartilage.Besides,the results of antioxidant activity showed that different fractions of OCS had a distinct DPPH radical,hydroxyl radical,and ABTS+radical scavenging activity.OCS-1 has the highest scavenging activities in DPPH and hydroxyl radical compared with other fractions,which showed a higher medicinal value.Those findings may lay some theoretical basis for the potential application development of OCS.
基金supported by the National Natural Science Foundation of China(32201994)。
文摘Sea buckthorn(Hippophae rhamnoides L.)is a natural homologous substance of medicine and food.Polysaccharide,as one of its primary active components,has very superior biological activity and can be used as a dietary supplement for functional foods,with good commercial prospects.Although initial progress has been made in the study of sea buckthorn polysaccharides,related studies have been fragmented and lacked systematic and generalization.This manuscript presents a critical analysis and systematic summary of the extraction and purification methods,structural characterization and physicochemical properties,biological activity and potential mechanisms,and structure-activity relationships of sea buckthorn polysaccharides.Accumulating evidence has indicated that sea buckthorn polysaccharides,which were widely prepared by water extraction and column chromatography purifications,exhibited exhibit superior biological activities in vitro and in vivo,including antioxidant,immunomodulatory,anti-inflammatory,hepatorenal protective,antibacterial,antiviral,and prebiotic activities.After analysis,it was concluded that there is a correlation between the relevant activities of sea buckthorn polysaccharides and that the structure of sea buckthorn polysaccharides has a great influence on their biological activity.We reviewed the challenges and limitations of sea buckthorn polysaccharides,summarized the critical aspects,and provided suggestions for potential breakthroughs in the research and application of sea buckthorn polysaccharide.
基金supported by the National Natural Science Foundation of China (32102605)the Agricultural Science and Technology Innovation Program under Grant (CAAS-ASTIP-2020IAR)the Earmarked Fund for CARS (CARS-44)。
文摘Food allergens are mainly naturally-occurring proteins with immunoglobulin E(IgE)-binding epitopes.Understanding the structural and immunogenic characteristics of allergenic proteins is essential in assessing whether and how food processing techniques reduce allergenicity.We here discuss the impacts of food processing technologies on the modification of physicochemical,structural,and immunogenic properties of allergenic proteins.Detection techniques for characterizing changes in these properties of food allergens are summarized.Food processing helps to reduce allergenicity by aggregating or denaturing proteins,which masks,modifies,or destroys antigenic epitopes,whereas,it cannot eliminate allergenicity completely,and sometimes even improves allergenicity by exposing new epitopes.Moreover,most food processing techniques have been tested on purified food allergens rather than food products due to potential interference of other food components.We provide guidance for further development of processing operations that can decrease the allergenicity of allergenic food proteins without negatively impacting the nutritional profile.
基金the Beijing Natural Science Foundation(Grant Nos.JQ24010 and Z220020)the Fundamental Research Funds for the Central Universities,and the National Natural Science Foundation of China(Grant No.52273279)Project supported by the Electron Microscopy Laboratory of Peking University,China for the use of Nion U-HERMES200 scanning transmission electron microscopy.We thank Materials Processing and Analysis Center,Peking University,for assistance with TEM characterization.The electron microscopy work was through a user project at Center of Oak Ridge National Laboratory(ORNL)for Nanophase Materials Sciences(CNMS),which is a DOE Office of Science User Facility.
文摘Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the methods in defect controlcurrently face challenges with overly large operational areas and a lack of precision in targeting specific defects. Therefore,we propose a new method for the precise and universal defect healing of TMD materials, integrating real-time imaging withscanning transmission electron microscopy (STEM). This method employs electron beam irradiation to stimulate the diffusionmigration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy (MBE),and heal defects within the diffusion range. This approach covers defect repairs ranging from zero-dimensional vacancydefects to two-dimensional grain orientation alignment, demonstrating its universality in terms of the types of samples anddefects. These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEMfor defect healing, providing valuable experience for achieving atomic-level precise fabrication of TMD materials.
基金financially supported by the Key Projects of the National Research and Development Program of China(2018YFD0400204)。
文摘In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM).We analyzed their lipidlowering properties in vitro(water holding,oil holding swelling cholesterol and sodium cholate binding capacitises)and the hypolipidemic effects in mice.The results showed that tremella dietary fibers presented the infrared absorption spectrum characteristics of polysaccharides and the characteristic diffraction peaks of cellulose type I.SEM results indicated that the surface of insoluble dietary fiber(IDF)was porous,while the soluble dietary fiber(SDF)was relatively compact and spongy.IDF exhibited significantly higher water holding,oil holding,and swelling binding capacities than the corresponding SDF.However,SDF exhibited significantly higher viscosity than IDF.The results showed tremella dietary fibers were significant in swelling,water holding and oil holding,cholesterol and bile acids.In vivo experiment results in mice indicated that SDF has the best effect on hyperlipidemia mice than IDF and total dietary fiber(TDF).SDF showed that the total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)contents dropped by 28.33%,18.65%,and 48.97%,respectively,while high density lipoprotein cholesterol(HDL-C)content increased by 43.80%.Compared with the high-fat control(HCM)group,the arteriosclerosis index(AI)and liver index(LI)of the SDF group mice showed significant differences,indicating that SDF has a good auxiliary effect of lowering blood lipids.The administration of tremella fibers improved the lipid metabolism disorderly situation of hyperlipidemia mice.These results provide a reference for further research and rational development of T.fuciformis.
基金The authors would like to show deepest gratitude tothe Earmarked Fund for Jiangsu Agricultural Industry Technology System(JATS[2020]413)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX19_0682)forfinancial assistance.
文摘This study aimed to isolate and characterize the structures of glycoproteins from peas and determine their hypoglycemic activity.The crude pea glycoproteins(PGP)were extracted by hot water and purified by diethylaminoethyl(DEAE)-Sepharose chromatography and Sephadex G-100 size-exclusion chromatography in sequence.Then three main fractions were obtained,namely PGP1,PGP2 and PGP3,with molecular weights of 897615,846740 and 1194692 Da,respectively.The physical and chemical properties of the three fractions were evaluated and compared by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR),scanning electron microscope(SEM),high performance liquid chromatography(HPLC)and other analytical techniques.The fraction PGP2 with the highest hypoglycemic activity,was screened using the Caco-2 monolayer cell model.It can inhibit the uptake of glucose in the small intestine,as well as the activities of maltase and sucrase.After simulated gastrointestinal digestion,PGP2 signifi cantly enhanced the inhibitory effect of α-glucosidase,and slightly reduced the inhibitory ability ofα-amylase.In summary,PGP2 possessed strong hypoglycemic activity after digestion.These results indicated that PGP2 has the potential to be developed into a functional food or natural medicine for the treatment of type 2 diabetes mellitus.
基金the financial support of the National Natural Science Foundation of China(Nos.21875206,21403187)the Natural Science Foundation of Hebei Province(No.B2019203487)the open project in Key Lab Adv.Energy Mat.Chem.(Nankai University)。
文摘The development of novel organic electrode materials is of great significance for improving the reversible capacity and cycle stability of rechargeable batteries.Before practical application,it is essential to characterize the electrode materials to study their structures,redox mechanisms and electrochemical performances.In this review,the common characterization methods that have been adopted so far are summarized from two aspects:experimental characterization and theoretical calculation.The experimental characterization is introduced in detail from structural characterization,electrochemical characterization and electrode reaction chara cterization.The experimental purposes and working principles of various experimental characterization methods are briefly illustrated.As the auxilia ry means,theoretical calculation provides the theoretical basis for characterizing the electrochemical reaction mechanism of organic electrode materials.Through these characterizations,we will have a deep understanding about the material structures,electrochemical redox mechanisms,electrochemical properties and the relationships of structure-property.It is hoped that this review would help researchers to select the suitable characterization methods to analyze the structures and performances of organic electrode materials quickly and effectively.
基金the National Science and Technology Support Program of China(Grant No.2013BAD16B08).
文摘Allium cepa L.var.agrogatum Don(ALAP)is commonly consumed in China as well as other regions and has various beneficial health effects.A novel acidic polysaccharide(named ALAP-21)was obtained from ALAP by ultrasonic and microwave-assisted extraction and purification using DEAE-52 anion exchange and Sephadex G-100 columns.The monosaccharide composition,structural and antioxidative properties of ALAP-21 were investigated by GC–MS chromatography,FT-IR and NMR spectroscopies and three antioxidative activity tests in vitro.The results showed that ALAP-21 was a heteropolysaccharide composed of glucose,galacturonic acid,mannose,galactose,arabinose,rhamnose,xylose,fructose and glucuronic acid with a relative molar ratio of 26.282:27.546:11.400:4.781:2.467:2.445:3.622:1.106:1.753,owning(1→4)-β-d-Glcp,(1→4)-β-d-GalAp6Me3OA,(1→4)-β-d-Galp6OMe,(1→2)-β-l-Rhap,(1→4)-β-d-Manp glycosidic linkages.(1→4)-β-d-Glcp and(1→4)-β-d-GalAp6Me3OA residues might be the main components of the sugar chain backbone of ALAP-21.Furthermore,ALAP-21 exhibited high potential for DPPH radicals(82.02%),hydroxyl radicals(53.33%)and superoxide anion radicals(50.28%).These results provide a reference for further research and rational development of ALAP polysaccharides.
基金The authors thank for National Natural Science Foundation of China(U1710106)for financial support.
文摘Coal chemical wastewater(CCW)with the features of high toxicity and poor biodegradability is a big issue in environmental remediation,posing a great threat to aquatic ecosystems and to human beings.Such complex molecular mixtures are notoriously difficult to characterize without initial physical separation.Herein,we present the 3D diffusion ordered spectroscopy(DOSY)analysis for CCW using DOSY-COSY and DOSY-HSQC methods,the advantages of this strategy have been demonstrated in the analysis of mixtures of aliphatic oxygenates and aromatic compounds,before being implemented on a genuine CCW sample in this study.The results showed that 3D DOSY is a robust and reliable tool for providing superior resolution and virtual separation of complex pollutants,and can be used as a general approach for structural elucidation.
文摘Anatase TiO_(2)nanospindles containing 89%exposed{101}facets(TIO_(2)-101)and nanosheets with 77%exposed{001}facets(TiO_(2)-001)were hydrothermally synthesized and used as supports for Pd catalysts.The effects of the TiO_(2)materials on the catalytic performance of Pd/TiO_(2)-101 and Pd/TiO_(2)-001 catalysts were investigated in the selective hydrogenation of acetylene to polymer-grade ethylene.The PdfTiO_(2)-101 catalyst exhibited enhanced performance in terms of acetylene conversion and ethylene yield.To understand these effects,the catalysts were characterized by H_(2)temperature-programmed desorption(H_(2)-TPD),H_(2)temperature-programmed reduction(H=-TPR),transmission electron microscopy(TEM),pulse CO chemisorption,X-ray photoelectron spectroscopy(XPS),and thermogravimetric analysis(TGA).The TEM and CO chemisorption results confirmed that Pd nanoparticles(NPs)on the TiO_(2)-101 support had a smaller average particle size(1.53 nm)and a higher dispersion(15.95%)than those on the TiO_(2)-001 support(average particle size of 4.36 nm and dispersion of 9.06%).The smaller particle size and higher dispersion of Pd on the Pd/TiO_(2)-101 catalyst provided more reaction active sites,which contributed to the improved catalytic activity of this supported catalyst.
基金National Natural Science Foundation of China(No.50473003)
文摘A mass of nanoparticles/nanorods were formed on a simultaneously deposited gran- ular film by plasma enhanced chemical vapor deposition （PECVD） of perfluorohexane at atmo- spheric pressure without any catalysts or templates. Scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS） were used to characterize the morphology and the chem- ical compositions of nanoparticles. The average size of particles is about 100 nm and the length of synthesized nanorods is between 1 μm and 2.5/tm. The analyses of transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HRTEM）, selected area electron diffraction（SAED） and X-ray diffraction （XRD） reveals that the nanoparticles and nanorods are crystalline.
基金Supported by the Natural Science Foundation of Jiangxi Province under Grant No 20133ACB20005the Key Program of National Natural Science Foundation of China under Grant No 41330318+3 种基金the Key Program of Science and Technology Research of Ministry of Education under Grant No NRE1515the Foundation of Training Academic and Technical Leaders for Main Majors of Jiangxi Province under Grant No 20142BCB22006the Research Foundation of Education Bureau of Jiangxi Province under Grant No GJJ14501the Engineering Research Center of Nuclear Technology Application(East China Institute of Technology)Ministry of Education under Grant NoHJSJYB2016-1
文摘For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.
基金financially supported by the National Natural Science Foundation of China(NSFC)(22088102)supported by the National Natural Science Foundation of China(21633009,21633010,21925206)+4 种基金the Cooperation Fund of Dalian National Laboratory for Clean Energy(DNL201913)International Partnership Program of Chinese Academy of Sciences(121421KYSB20190025)the DICP foundation of innovative research(DICPI201927)Strategic Priority Research Pro-gram of Chinese Academy of Sciences(XDB17000000)support from Liaoning Revitalization Talents Program(XLYC1807241)。
文摘The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging to obtain photocatalyst with absorption edge of above 550 nm.Here we report a novel Sn^(2+)-based oxyfluoride Sn_(2)TiNbO_6 F(STNOF)photocatalyst with a pyrochlore structure to exhibit an extended absorption edge to 650 nm and dual functionalities of both water reduction and oxidation.Density functional theory calculations suggest that the unprecedented broad-spectrum response of STNOF is mainly ascribed to the strengthened hybridization between O 2 p and Sn 5 s orbitals remarkably upshifting the valence band,which is caused by the distortion and compressive strain in the Sn06 F2 dodecahedron with second-order Jahn-Teller effect due to partial fluorine substitution.The structural distortion and compressive strain are experimentally confirmed by the Fourier-transformed extended X-ray absorption fine spectra.As probe tests of the photocatalytic functionalities,water reduction and oxidation half reactions were examined to see obvious H_(2)and O_(2)evolution under visible light irradiation.This work may provide an alternative strategy of developing extended visible light responsive semiconductors for promising solar energy conversion.
基金Project supported by the National Natural Science Foundation of China （Grant No 50240420656）.
文摘Using transmission electron microscopy （TEM） and x-ray diffraction analysis, we have studied the structural and morphological evolution of highly Er/Yb co-doped A1203 films in the temperature range from 600℃-900℃. By comparison with TEM observation, the annealing behaviours of photoluminescence （PL） emission and optical loss were found to have relation to the structure and morphology. The increase of PL intensity and optical loss above 800℃ might result from the crystallization of amorphous Al2O3 films. Based on the study on the structure and morphology, a rate equation propagation model of a multilevel system was used to calculate the optical gains of Er-doped Al2O3 planar waveguide amplifiers involving the variation of PL efficiency and optical loss with annealing temperature. It was found that the amplifiers had an optimized optical gain at the temperature corresponding to the minimum of optical loss, rather than at the temperature corresponding to the maximum of PL efficiency, suggesting that the optical loss is a key factor for determining the optical gain of an Er-doped Al2O3 planar waveguide amplifier.
基金the the Open Project Program of National R&D Center for Edible Fungus Processing Technology(20200110)。
文摘Tremella fuciformis polysaccharide(TFP) is an important bioactive substance in T. fuciformis, which contributes to its application as medicine and food. In the present work, TFP was extracted with enzymatic combined with wet beating and its physicochemical as well as biological activities were investigated in the study. The result showed that the purity of TFP1 reached 92.14%(m/m). The TFP1, purified by DEAE column, had a molecular weight(Mw) of 5.8 × 10^(3) k Da and consisted mainly of mannose, xylose, fucose, glucose and glucuronic acid at a molar ratio of 1.91 : 0.1 : 2.49 : 6.23 : 0.95. The structure of TFP1 was preliminarily investigated by infrared spectroscopy, nuclear magnetic resonance and atomic force microscope(AFM) analysis. Moreover, the antioxidant assays showed that TFP1 could scavenge DPPH, ABTS+ and hydroxyl radicals. The excellent water holding capacity of TFP1 implied its application in the food, pharmaceutical andcosmetic industries.
基金supported by the Scientific Research Foundation of Graduate School of Fujian Agriculture and Forestry University(1122yb065)the Program for Leading Talent in Fujian Provincial University(660160190)。
文摘This study was to investigate the structure and rat fecal microbial fermentation properties of a polysaccharide fraction(PHP2)isolated from the red marine alga Porphyra haitanensis.PHP2 was characterized as a sulfated glucogalactan,with a hypothetical backbone structure of→4)Gα(1→6)G4 Sβ(1→4)Glc(1→and a side chain of Man(1→6)Glc.PHP2 had an irregular spherical chain conformation.The 16 S r RNA sequence analysis revealed that PHP2 modulated the rat fecal micro-flora composition,with a similar effect to inulin,changing the dominant genus(Lactobacillus and Escherichia-Shigella)and promoting the growth of organisms that degrade sulfur-containing polysaccharides,such as Desulfovibrio,Ruminococcaceae_UCG-005,and Ruminococcus_2.PHP2 can promote production of acetic,propionic and butyric acid by rat fecal micro-flora.Prediction of metabolic function suggested that PHP2 could modulate cholesterol metabolism.The sulfated glucogalactan fermentation behavior may be associated with its monosaccharide composition,chain branching and chain conformation.PHP2 appeared to have considerable potential as functional food,and was associated with sulfur-containing polysaccharides in general.
