This study investigated the current status of course satisfaction among 416 undergraduate students majoring in preschool education from four universities in China.And it explored the predictive effects of five influen...This study investigated the current status of course satisfaction among 416 undergraduate students majoring in preschool education from four universities in China.And it explored the predictive effects of five influencing factors(teacher instruction,course management,course setting,course environment,and course resources)on student satisfaction.Through SPSS data analysis,the findings revealed that:1.the mean value of course experience was M=3.861(out of 5);2.there were differences in the satisfaction of undergraduate students'course experience by different background variables;3.course,course resources,and loyalty had significant predictive power on undergraduate students'satisfaction with course experience;4.instructor instruction(TI)did not significantly predict students'satisfaction with course experience(SCES)(p>0.001);5.Faculty instruction(TI)in this study had the highest mean satisfaction score(M=4.191)and the mean satisfaction score was only(M=3.861).The results show that the current status of course satisfaction among Chinese preschool undergraduates is at an moderate level,and there is more space for improvement;although students'satisfaction with teacher instruction(TI)is high,effective teacher instruction does not have a substantial impact on the acquisition of SCES or general competencies,and this passive learning and teaching style leads to a lack of independent learning and active participation among Chinese preschool undergraduate students.展开更多
The fuzzy mathematic model was used to evaluate the water quality of six sections in the upper reaches of the Qingshui River Basin. The results showed that tiie water of grade I accounted for a high proportion, with m...The fuzzy mathematic model was used to evaluate the water quality of six sections in the upper reaches of the Qingshui River Basin. The results showed that tiie water of grade I accounted for a high proportion, with mild pollution and strong self-deaning ability; the pollutants (f.g. ammonium nitrogen, total phosphorus and fluoride) at each section mainly came from phosphate mines and phosphorus chemical companies; and the water quaEty among different sections was in the order Chayuan, Xingren Bridge, Xiasi, Locomotive Section, Yingpan, Panghai (from superiority to inferiority). This study has important reference values fof improving the water envifonment, saf^uarding the safely of drinkiiig water supply and scientifically preventing and conttolling water pollution, in the basin.展开更多
The electrode material is regarded as one of the key factors that determine the performance of lithium-ion batteries(LIBs).However,it is still a challenge to search for an anode material with large capacity,low diffus...The electrode material is regarded as one of the key factors that determine the performance of lithium-ion batteries(LIBs).However,it is still a challenge to search for an anode material with large capacity,low diffusion barrier,and good stability.In the present work,two new CrP_(2) monolayers(Pmmn-CrP_(2) and Pmma-CrP_(2)) are predicted by means of first principles swarm structure search.Our study shows that both the two CrP_(2) monolayers have high dynamical and thermal stability,as well as excellent electron conductivity.Additionally,Pmmn-CrP_(2) exhibits a remarkably high storage capacity of 705 mA·h·g^(-1) for Li,meanwhile the diffusion energy barrier of Li on the surface of this monolayer is 0.21 eV,ensuring it as a high-performance anode material for LIBs.We hope that our study will inspire researchers to search for new-type two-dimensional(2D) transition metal phosphides for the electrode materials of LIB s.展开更多
A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific...A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific foundations for the improvement and applications of Camellia oleifera protein adhesive by the reaction of model compounds.The experimental results demonstrate that,under alkaline conditions,formaldehyde is easier to react with Camellia oleifera protein by quicker reaction and lower curing temperature.Under acid conditions,amino hydroxymethylated structure of aliphatic series from LAG is difficult to form stable reactive intermediates and further polycondensation.Hydroxymethylation of end acylamino and peptide bond amino from LAG is relatively weak.Under alkaline conditions,the free aliphatic amino and acylamino of LAG both can make hydroxymethylation reaction with formaldehyde.In the polycondensation,hydroxymethyl amide is the initial structure and the reactive intermediate is produced by E1cb reaction of hydroxymethyl amide.Methylene bridge bonds and methylene ether bonds are structures of the polycondensation products,which are competing reactions.The former is mainly formed by the reaction between alkaline reactive intermediate and amino of aliphatic series,and the latter is produced by the reaction of reactive intermediate and amino of hydroxymethyl aliphatic series with hydroxymethyl amide.展开更多
[Objectives]The paper was to investigate and identify the fungal diseases of wild and red heart kiwifruit in Qiandongnan Prefecture.[Methods]The pathogenic fungi were isolated from diseased leaves and fruits of wild a...[Objectives]The paper was to investigate and identify the fungal diseases of wild and red heart kiwifruit in Qiandongnan Prefecture.[Methods]The pathogenic fungi were isolated from diseased leaves and fruits of wild and red heart kiwifruit by tissue separation method.DNA sequencing was carried out by using the sequence analysis of ribosomal r DNA-ITS region,and molecular evolutionary trees were built by using MEGA 4.0 software.Finally,the pathogenic fungi were classified and identified by combining morphological observation.[Results]The main fungal diseases were anthracnose caused by Colletotrichum gloeosporioides on wild kiwifruit,fruit anthracnose caused by C.acutatum on red heart kiwifruit,leaf soft rot caused by Fusarium incarnatum on red heart kiwifruit,and brown spot caused by Alternaria alternata on red heart kiwifruit.[Conclusions]The study may provide some theoretical basis for the control of kiwifruit diseases in Qiandongnan Prefecture.展开更多
The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and ...The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.展开更多
Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects o...Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.展开更多
Loquat(Eriobotrya japonica)is a popular fruit and medicinal plant.Here,a high-quality draft genome of the E.japonica‘Big Five-pointed Star’cultivar that covers~98%(733.32Mb)of the estimated genome size(749.25 Mb)and...Loquat(Eriobotrya japonica)is a popular fruit and medicinal plant.Here,a high-quality draft genome of the E.japonica‘Big Five-pointed Star’cultivar that covers~98%(733.32Mb)of the estimated genome size(749.25 Mb)and contains a total of 45,492 protein-coding genes is reported.Comparative genomic analysis suggests that the loquat genome has evolved a unique genetic mechanism of chromosome repair.Resequencing data from 52 loquat cultivars,including 16 white-fleshed and 36 yellow-fleshed variants,were analyzed,and the flower,leaf,and root metabolomes of‘Big Five-pointed Star’were determined using a UPLC-ESI-MS/M system.A genome-wide association study identified several candidate genes associated with flesh color in E.japonica,linking these phenotypes to sugar metabolism.A total of 577 metabolites,including 98 phenolic acids,95 flavonoids,and 28 terpenoids,were found,and 191 metabolites,including 46 phenolic acids,33 flavonoids,and 7 terpenoids,showed no differences in concentration among the leaves,roots,and flowers.Candidate genes related to the biosynthesis of various medicinal ingredients,such as phenolics,flavonoids,terpenoids,and polysaccharides,were identified.Some of these genes were confirmed to be members of expanding gene families,suggesting that the high concentrations of beneficial metabolites in loquat may be associated with the number of biosynthetic genes in this plant.In summary,this study provides fundamental molecular insights into the nutritional and medical properties of E.japonica.展开更多
Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism...Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.展开更多
Based on the ESI-MS and ^(13)C-NMR analysis of the forms of glyoxal in acidic and alkaline solutions,the soy-based adhesive cross-linked by glyoxal was prepared in this work.The results showed that glyoxal existed in ...Based on the ESI-MS and ^(13)C-NMR analysis of the forms of glyoxal in acidic and alkaline solutions,the soy-based adhesive cross-linked by glyoxal was prepared in this work.The results showed that glyoxal existed in water in different forms at different pH levels.Under alkaline conditions,glyoxal transformed to glycolate through the intramolecular disproportionation reaction.Under acidic conditions,although some of glyoxal transformed to glycolate as what happened under alkaline conditions,most of glyoxal molecules existed in the form of fiveor six-membered cyclic ether structure.No ethylene tetraol or free aldehyde group was actually detected under these conditions.Although glyoxal reacted with soy protein under both acidic and alkaline conditions,alkaline conditions were more favorable for the improvement of mechanical performance and water resistance of soybased adhesives than acid conditions.展开更多
To better understand the effects of forest suc- cession on soil microbial activity, a comparison of soil microbial properties and nutrients was conducted between three forest types representing a natural forest succes...To better understand the effects of forest suc- cession on soil microbial activity, a comparison of soil microbial properties and nutrients was conducted between three forest types representing a natural forest succession chronosequence. The study compared a pine (Pinus mas- soniana) forest (PF), a pine and broadleaf mixed forest (MF) and an evergreen broadleaf forest (BF), in the Yingzuijie Biosphere Reserve, Hunan Province, China. Results showed that soil nutrients in the MF and BF plots were higher than in the PF plots. The range in microbial biomass carbon followed a similar pattem with Be havingthe greatest values, 522-1022 mg kg-1, followed by Mr 368-569 mg kg-1, and finally, PF 193--449 mg kg-1. Soil nutrients were more strongly correlated with microbial biomass carbon than basal respiration or metabolic quo- tient. Overall, forest succession in the study site improved soil microbial properties and soil fertility, which in turn can increase primary productivity and carbon sequestration.展开更多
Mesoporous chromium aluminophosphate (CrAIPO) was successfully synthesized via solid state reaction (SSR) route at low temperature in the presence of a cationic surfactant cetyltrimethyl ammonium bromide (CTAB) ...Mesoporous chromium aluminophosphate (CrAIPO) was successfully synthesized via solid state reaction (SSR) route at low temperature in the presence of a cationic surfactant cetyltrimethyl ammonium bromide (CTAB) and inorganic sources such as A1C13 · 6H20, CrCI3 · 6H20 and NaH2PO4 · 2H20. Characterizations by means of powder X-ray diffraction (XRD), N2 adsorption- desorption, high resolution transmission electron microscopy (HR-TEM), scanning electron micrography (SEM), energy dispersion spectroscopy (EDS), thermo-gravimetry (TG), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet visible light spectroscopy (UV-Vis) were carried out to understand both the pore characteristics and electron transition route of these obtained materials. The experimental results show that the meso-CrA1PO materials with various Cr/A1 molar ratios possess a mesostructure and a specific surface area of 193 to 310 m2/g corresponding to an average pore size of 5.5 to 2.2 rim, respectively. The maxium content of Cr in meso-CrA1PO materials synthesized via SSR route can achieve 16.7wt%, being significantly higher than that of the meso-CrA1PO prepared via a conventional sol-gel route. Meanwhile, the formation mechanism of the meso-CrA1PO was also proposed.展开更多
Let F be a family of mermorphic functions in a domain D, and let a, b, c be complex numbers, a ≠ b. If for each f ∈ F, the zeros of f-c are of multiplicity ≥ k + 1, and -↑Ef(k)(a) belong to -↑Ef (a), -↑Ef...Let F be a family of mermorphic functions in a domain D, and let a, b, c be complex numbers, a ≠ b. If for each f ∈ F, the zeros of f-c are of multiplicity ≥ k + 1, and -↑Ef(k)(a) belong to -↑Ef (a), -↑Ef(k)(b)belong to -↑Ef (b), then F is normal in D.展开更多
[Objective] This study aimed to investigate the enzymatic kinetics of polyphenol oxidase in peel of Nephelium lappaceum to explore the environmental factors affecting its catalytic activity. [ Method ] With N. lappace...[Objective] This study aimed to investigate the enzymatic kinetics of polyphenol oxidase in peel of Nephelium lappaceum to explore the environmental factors affecting its catalytic activity. [ Method ] With N. lappaceum peel as the experimental material and catechol as substrate, effects of temperature, pH, four inhibitors (EDTA, Vc, sodium bisulfite and citric acid) and substrate concentration on the activity of polyphenol oxidase were investigated. [ Result] The optimal temperature for polyphenol oxidase in N. lappaceum peel was 40 %, and the optimal pH was 6.8. EDTA, Vc, sodium bisulfite and citric acid all showed ideal in- hibitory effects on the activity of polyphenol oxidase; specifically, EDTA had the strongest inhibitory effect. [ Conclusion] At low temperature, EDTA, Vc, sodi- um bisulflte and citric acid with certain concentrations can inhibit the catalytic activity of polyphenol oxidase in peel of N. lappaceum, extend the storage and trans- portation time of N. lappaceum fruit, and inhibit the browning. This study provides theoretical basis for the development and utilization of polyphenol oxidase in peel of N. lappaceum.展开更多
Fenton oxidation was used as the pretreatment of 2-chlorophenol wastewater with the objective of dechlorination, as it was considered that after breakage of aryl—Cl bond, the generated intermediates may be easily bio...Fenton oxidation was used as the pretreatment of 2-chlorophenol wastewater with the objective of dechlorination, as it was considered that after breakage of aryl—Cl bond, the generated intermediates may be easily biodegraded. Hence, the optimization of pH and the low Fenton reagent doses for dechlorination was investigated. More than 99% dechlorination is obtained at the optimal pH 4 and the Fenton reagent doses of 86 mmol/L H2 O2 and 2.87 mmol/L Fe2+. The corresponding 2-chlorophenol is degraded completely, 80.02% COD is also removed, and the biodegradability, evaluated in terms of the BOD5 /COD ratio, is increased up to 0.41. To test the effect of this pretreatment, the pretreated 2-chlorophenol wastewater was fed to a sequencing batch reactor(SBR). The results show that complete mineralization is achieved. It is demonstrated that, for the treatment of recalcitrant compounds like 2-chlorophenol, the Fenton pretreatment could be quite effective and economical for enhancing the biodegradability in a Fenton-biological coupled system.展开更多
Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study.Chemical structural changes of lignin which was processed by plasma as well as bonding strength,tensile pr...Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study.Chemical structural changes of lignin which was processed by plasma as well as bonding strength,tensile property,curing performance and thermal property of the prepared phenol formaldehyde resin which was modified by the plasma processed lignin were analyzed.Results demonstrated that:(1)Alkali lignin was degraded after the plasma processing.The original groups were destroyed,and the aromatic rings collected abundant free radicals and oxygen-containing functional groups like hydroxyls,carbonyls,carboxyls and acyls were introduced into increase the reaction activity of lignin significantly.(2)The introduction of alkali lignin decreased the free formaldehyde content and increased bonding strength and toughness of the prepared phenol formaldehyde resin,especially after the introduction of lignin treated with plasma.(3)The introduction of alkali lignin led to high curing temperature for the prepared phenol formaldehyde resin,but that was reduced by the plasma processed alkali lignin.(4)The introduction of alkali lignin could also increase thermal stability of phenol formaldehyde resin,but that was modified by plasma processed alkali lignin was better than the unprocessed lignin.Based on the results,the plasma processed lignin was used to modify phenol formaldehyde resin,which could increase the strength and toughness of phenol formaldehyde resin significantly.展开更多
Mesoporous aluminum-doped titanium dioxide(Al-TiO2) materials with high specific surface areas were prepared via a solid-state reaction route.The properties of these materials were characterized by X-ray diffraction(X...Mesoporous aluminum-doped titanium dioxide(Al-TiO2) materials with high specific surface areas were prepared via a solid-state reaction route.The properties of these materials were characterized by X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),energy dispersive spectroscopy(EDS),N2 absorption-desorption,ultraviolet visible light spectroscopy(UV-Vis) and electrochemical spectroscopy.The results show that the mesoporous structure of the product with ethanol is composed of anatase laced crystal walls with amorphous grain boundaries formed gradually by degradation.Compared with those without ethanol,these samples possess larger crystallite size since ethanol decreases the pore size at higher temperature.With the increase of ethanol amount,however,the crystallite size will grow.The amorphous grain boundaries in the mesoporous material,with a large impedance and low incidental cyclic potential,are difficult to effectively degrade and the phase transformation temperature is changed from 500 to 550℃.The growth rate of Al-TiO2 crystallites that obeys the quadratic polynomial equation may be controlled.展开更多
The Ecological Footprint and Development Capacity Model were used to analyze the ecological environment development capability of the Qingshui River Basin from 2000 to 2015. On this basis,the ecological environment de...The Ecological Footprint and Development Capacity Model were used to analyze the ecological environment development capability of the Qingshui River Basin from 2000 to 2015. On this basis,the ecological environment development capacity of the Qingshui River Basin from 2016 to 2020 was dynamically predicted using the GM( 1,1) model. The results showed that the Qingshui River Basin has a strong capacity for sustainable development of the ecological environment,but it is increasingly stressed by the ecological carrying capacity. The potential unsustainability of the ecological environment is facing severe challenges. In the next 5 years,the development capacity of the ecological environment will show a growth trend,but the increase is not large,reflecting the limited development potential. Its capacity for sustainable development needs to be improved.展开更多
In this paper, we study the global and pullback attractors for a strongly damped wave equation with delays when the force term belongs to different space. The results following from the solution generate a compact set.
文摘This study investigated the current status of course satisfaction among 416 undergraduate students majoring in preschool education from four universities in China.And it explored the predictive effects of five influencing factors(teacher instruction,course management,course setting,course environment,and course resources)on student satisfaction.Through SPSS data analysis,the findings revealed that:1.the mean value of course experience was M=3.861(out of 5);2.there were differences in the satisfaction of undergraduate students'course experience by different background variables;3.course,course resources,and loyalty had significant predictive power on undergraduate students'satisfaction with course experience;4.instructor instruction(TI)did not significantly predict students'satisfaction with course experience(SCES)(p>0.001);5.Faculty instruction(TI)in this study had the highest mean satisfaction score(M=4.191)and the mean satisfaction score was only(M=3.861).The results show that the current status of course satisfaction among Chinese preschool undergraduates is at an moderate level,and there is more space for improvement;although students'satisfaction with teacher instruction(TI)is high,effective teacher instruction does not have a substantial impact on the acquisition of SCES or general competencies,and this passive learning and teaching style leads to a lack of independent learning and active participation among Chinese preschool undergraduate students.
基金Sponsored by Scientific and Technological Cooperation Project of Guizhou Province(LH20157758)Youth Science and Technology Talent Growth Project of Education Department of Guizhou Province(KY[2017]336)
文摘The fuzzy mathematic model was used to evaluate the water quality of six sections in the upper reaches of the Qingshui River Basin. The results showed that tiie water of grade I accounted for a high proportion, with mild pollution and strong self-deaning ability; the pollutants (f.g. ammonium nitrogen, total phosphorus and fluoride) at each section mainly came from phosphate mines and phosphorus chemical companies; and the water quaEty among different sections was in the order Chayuan, Xingren Bridge, Xiasi, Locomotive Section, Yingpan, Panghai (from superiority to inferiority). This study has important reference values fof improving the water envifonment, saf^uarding the safely of drinkiiig water supply and scientifically preventing and conttolling water pollution, in the basin.
基金Project supported by the National Natural Science Foundation of China(Grant No.11964006)the Science and Technology Foundation of Kaili University(Grant No.2022ZD06)the Specialized Research Fund for the Doctoral Program of Kaili University(Grant Nos.BS201601 and BS201702)。
文摘The electrode material is regarded as one of the key factors that determine the performance of lithium-ion batteries(LIBs).However,it is still a challenge to search for an anode material with large capacity,low diffusion barrier,and good stability.In the present work,two new CrP_(2) monolayers(Pmmn-CrP_(2) and Pmma-CrP_(2)) are predicted by means of first principles swarm structure search.Our study shows that both the two CrP_(2) monolayers have high dynamical and thermal stability,as well as excellent electron conductivity.Additionally,Pmmn-CrP_(2) exhibits a remarkably high storage capacity of 705 mA·h·g^(-1) for Li,meanwhile the diffusion energy barrier of Li on the surface of this monolayer is 0.21 eV,ensuring it as a high-performance anode material for LIBs.We hope that our study will inspire researchers to search for new-type two-dimensional(2D) transition metal phosphides for the electrode materials of LIB s.
基金Funded by the National Natural Science Foundation of China (32160348)the Department Program of Guizhou Province (ZK[2021]162 and[2019]2325)+1 种基金the Special Project of“Doctor Professor Service Group of Kaili University (BJFWT201906)the Cultivation Project of Guizhou University of China ([2019]37)。
文摘A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific foundations for the improvement and applications of Camellia oleifera protein adhesive by the reaction of model compounds.The experimental results demonstrate that,under alkaline conditions,formaldehyde is easier to react with Camellia oleifera protein by quicker reaction and lower curing temperature.Under acid conditions,amino hydroxymethylated structure of aliphatic series from LAG is difficult to form stable reactive intermediates and further polycondensation.Hydroxymethylation of end acylamino and peptide bond amino from LAG is relatively weak.Under alkaline conditions,the free aliphatic amino and acylamino of LAG both can make hydroxymethylation reaction with formaldehyde.In the polycondensation,hydroxymethyl amide is the initial structure and the reactive intermediate is produced by E1cb reaction of hydroxymethyl amide.Methylene bridge bonds and methylene ether bonds are structures of the polycondensation products,which are competing reactions.The former is mainly formed by the reaction between alkaline reactive intermediate and amino of aliphatic series,and the latter is produced by the reaction of reactive intermediate and amino of hydroxymethyl aliphatic series with hydroxymethyl amide.
基金Supported by Identification and Control Analysis of Diseases and Insect Pests of Kiwifruit in Qiandongnan Prefecture(QKH H[2017]7178)Guizhou Key Laboratory of Qiandongnan Ethnic Characteristic Food Research and Development(QJH KY[2017]011)Talent Team Project of Guizhou Department of Education(QJHRCTD[2015]70)。
文摘[Objectives]The paper was to investigate and identify the fungal diseases of wild and red heart kiwifruit in Qiandongnan Prefecture.[Methods]The pathogenic fungi were isolated from diseased leaves and fruits of wild and red heart kiwifruit by tissue separation method.DNA sequencing was carried out by using the sequence analysis of ribosomal r DNA-ITS region,and molecular evolutionary trees were built by using MEGA 4.0 software.Finally,the pathogenic fungi were classified and identified by combining morphological observation.[Results]The main fungal diseases were anthracnose caused by Colletotrichum gloeosporioides on wild kiwifruit,fruit anthracnose caused by C.acutatum on red heart kiwifruit,leaf soft rot caused by Fusarium incarnatum on red heart kiwifruit,and brown spot caused by Alternaria alternata on red heart kiwifruit.[Conclusions]The study may provide some theoretical basis for the control of kiwifruit diseases in Qiandongnan Prefecture.
基金Funded by the National Natural Science Foundation of China(No.32160348)the Department Program of Guizhou Province(No.ZK[2021]162)+1 种基金the Guizhou Province Science and Technology Plan Project(No.[2020]1Y128)the Forestry Department Foundation of Guizhou Province of China(Nos.J[2022]21 and[2020]C14)。
文摘The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.
基金funded by the National Natural Science Foundation of China (32160348)Forestry Science and Technology Research Project of Guizhou Forestry Bureau (J[2022]21 and[2020]C14)+1 种基金Department Program of Guizhou Province ([2020]1Y128)the Cultivation Project of Guizhou University of China ([2019]37).
文摘Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.
基金This work was funded by the National Natural Science Foundation of China(31560091)the Science and Technology plan project of Guizhou Province[(2019)4318].
文摘Loquat(Eriobotrya japonica)is a popular fruit and medicinal plant.Here,a high-quality draft genome of the E.japonica‘Big Five-pointed Star’cultivar that covers~98%(733.32Mb)of the estimated genome size(749.25 Mb)and contains a total of 45,492 protein-coding genes is reported.Comparative genomic analysis suggests that the loquat genome has evolved a unique genetic mechanism of chromosome repair.Resequencing data from 52 loquat cultivars,including 16 white-fleshed and 36 yellow-fleshed variants,were analyzed,and the flower,leaf,and root metabolomes of‘Big Five-pointed Star’were determined using a UPLC-ESI-MS/M system.A genome-wide association study identified several candidate genes associated with flesh color in E.japonica,linking these phenotypes to sugar metabolism.A total of 577 metabolites,including 98 phenolic acids,95 flavonoids,and 28 terpenoids,were found,and 191 metabolites,including 46 phenolic acids,33 flavonoids,and 7 terpenoids,showed no differences in concentration among the leaves,roots,and flowers.Candidate genes related to the biosynthesis of various medicinal ingredients,such as phenolics,flavonoids,terpenoids,and polysaccharides,were identified.Some of these genes were confirmed to be members of expanding gene families,suggesting that the high concentrations of beneficial metabolites in loquat may be associated with the number of biosynthetic genes in this plant.In summary,this study provides fundamental molecular insights into the nutritional and medical properties of E.japonica.
基金Funded by the Science and Technology Department Program of Guizhou Province (ZK[2021]162 and [2019]2325)the Special Project of"Doctor Professor Service Group of Kaili University (BJFWT201906)+1 种基金the Cultivation Project of Guizhou University of China ([2019]37)the Camellia Engineering Technology Research Center of Guizhou Province ([2018]5252)。
文摘Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.
基金This work was supported by Science-technology Support Foundation of Guizhou Province of China(Nos.[2019]2325 and [2020]1Y125)the Growth Project of Young Scientific and Technological Talents in Colleges and Universities of Guizhou Province(No.[2019]184)+1 种基金Yunnan Fundamental Research Key Projects(No.2019FA012)National Natural Science Foundation of China(Nos.31870546 and 31800481).
文摘Based on the ESI-MS and ^(13)C-NMR analysis of the forms of glyoxal in acidic and alkaline solutions,the soy-based adhesive cross-linked by glyoxal was prepared in this work.The results showed that glyoxal existed in water in different forms at different pH levels.Under alkaline conditions,glyoxal transformed to glycolate through the intramolecular disproportionation reaction.Under acidic conditions,although some of glyoxal transformed to glycolate as what happened under alkaline conditions,most of glyoxal molecules existed in the form of fiveor six-membered cyclic ether structure.No ethylene tetraol or free aldehyde group was actually detected under these conditions.Although glyoxal reacted with soy protein under both acidic and alkaline conditions,alkaline conditions were more favorable for the improvement of mechanical performance and water resistance of soybased adhesives than acid conditions.
基金supported by International Science&Technology Cooperation Program of China(2012DFB30030)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05050205)+3 种基金Natural Science Foundation of Hunan province(2015JJ6050)Hunan forestry science and technology program(XLK201417)Youth Innovation Fund of Hunan Academy of forestry(2013LQJ08)The Twelfth Five-Year Plan in national science and technology for the environment field(2012BAC09B03-4)
文摘To better understand the effects of forest suc- cession on soil microbial activity, a comparison of soil microbial properties and nutrients was conducted between three forest types representing a natural forest succession chronosequence. The study compared a pine (Pinus mas- soniana) forest (PF), a pine and broadleaf mixed forest (MF) and an evergreen broadleaf forest (BF), in the Yingzuijie Biosphere Reserve, Hunan Province, China. Results showed that soil nutrients in the MF and BF plots were higher than in the PF plots. The range in microbial biomass carbon followed a similar pattem with Be havingthe greatest values, 522-1022 mg kg-1, followed by Mr 368-569 mg kg-1, and finally, PF 193--449 mg kg-1. Soil nutrients were more strongly correlated with microbial biomass carbon than basal respiration or metabolic quo- tient. Overall, forest succession in the study site improved soil microbial properties and soil fertility, which in turn can increase primary productivity and carbon sequestration.
基金Funded by the Program for New Century Excellent Talents in Universitythe Ministry of Education of China+3 种基金the National Natural Science Foundation of China (No.21061006)the Research of Natural Science and Technology Foundation of Guizhou Province ([2010]2006),Chinathe Natural Science Research Foundation of Education Bureau of Guizhou Province (No.2007083)the China Guizhou Province Characteristic Leading Academic Discipline Project in Material Physics and Chemistry (No.[2011]208)
文摘Mesoporous chromium aluminophosphate (CrAIPO) was successfully synthesized via solid state reaction (SSR) route at low temperature in the presence of a cationic surfactant cetyltrimethyl ammonium bromide (CTAB) and inorganic sources such as A1C13 · 6H20, CrCI3 · 6H20 and NaH2PO4 · 2H20. Characterizations by means of powder X-ray diffraction (XRD), N2 adsorption- desorption, high resolution transmission electron microscopy (HR-TEM), scanning electron micrography (SEM), energy dispersion spectroscopy (EDS), thermo-gravimetry (TG), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet visible light spectroscopy (UV-Vis) were carried out to understand both the pore characteristics and electron transition route of these obtained materials. The experimental results show that the meso-CrA1PO materials with various Cr/A1 molar ratios possess a mesostructure and a specific surface area of 193 to 310 m2/g corresponding to an average pore size of 5.5 to 2.2 rim, respectively. The maxium content of Cr in meso-CrA1PO materials synthesized via SSR route can achieve 16.7wt%, being significantly higher than that of the meso-CrA1PO prepared via a conventional sol-gel route. Meanwhile, the formation mechanism of the meso-CrA1PO was also proposed.
文摘Let F be a family of mermorphic functions in a domain D, and let a, b, c be complex numbers, a ≠ b. If for each f ∈ F, the zeros of f-c are of multiplicity ≥ k + 1, and -↑Ef(k)(a) belong to -↑Ef (a), -↑Ef(k)(b)belong to -↑Ef (b), then F is normal in D.
基金Supported by Leading Academic Discipline Project of Botany in Guizhou Province ([2011] No.275)College-level Planning Project of Kaili University(Z0804)+1 种基金Leading Academic Discipline Project of Botany from Kaili University (KZD2008002)Construction Project for Basic Course Teaching Team of Biological Science from Kaili University (JXTD201003)
文摘[Objective] This study aimed to investigate the enzymatic kinetics of polyphenol oxidase in peel of Nephelium lappaceum to explore the environmental factors affecting its catalytic activity. [ Method ] With N. lappaceum peel as the experimental material and catechol as substrate, effects of temperature, pH, four inhibitors (EDTA, Vc, sodium bisulfite and citric acid) and substrate concentration on the activity of polyphenol oxidase were investigated. [ Result] The optimal temperature for polyphenol oxidase in N. lappaceum peel was 40 %, and the optimal pH was 6.8. EDTA, Vc, sodium bisulfite and citric acid all showed ideal in- hibitory effects on the activity of polyphenol oxidase; specifically, EDTA had the strongest inhibitory effect. [ Conclusion] At low temperature, EDTA, Vc, sodi- um bisulflte and citric acid with certain concentrations can inhibit the catalytic activity of polyphenol oxidase in peel of N. lappaceum, extend the storage and trans- portation time of N. lappaceum fruit, and inhibit the browning. This study provides theoretical basis for the development and utilization of polyphenol oxidase in peel of N. lappaceum.
基金Project(11JJ2031) supported by the Natural Science Fund of Hunan Province,China
文摘Fenton oxidation was used as the pretreatment of 2-chlorophenol wastewater with the objective of dechlorination, as it was considered that after breakage of aryl—Cl bond, the generated intermediates may be easily biodegraded. Hence, the optimization of pH and the low Fenton reagent doses for dechlorination was investigated. More than 99% dechlorination is obtained at the optimal pH 4 and the Fenton reagent doses of 86 mmol/L H2 O2 and 2.87 mmol/L Fe2+. The corresponding 2-chlorophenol is degraded completely, 80.02% COD is also removed, and the biodegradability, evaluated in terms of the BOD5 /COD ratio, is increased up to 0.41. To test the effect of this pretreatment, the pretreated 2-chlorophenol wastewater was fed to a sequencing batch reactor(SBR). The results show that complete mineralization is achieved. It is demonstrated that, for the treatment of recalcitrant compounds like 2-chlorophenol, the Fenton pretreatment could be quite effective and economical for enhancing the biodegradability in a Fenton-biological coupled system.
基金supported by National Natural Science Foundation of China(No.31800481)Yunnan Fundamental Research Key Projects(No.2019FA012)+2 种基金Science-Technology Support Foundation of Guizhou Province of China(Nos.[2019]2308,[2020]1Y125)Forestry Department Foundation of Guizhou Province of China(No.[2018]13)Cultivation Project of Guizhou University of China(No.[2019]37).
文摘Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study.Chemical structural changes of lignin which was processed by plasma as well as bonding strength,tensile property,curing performance and thermal property of the prepared phenol formaldehyde resin which was modified by the plasma processed lignin were analyzed.Results demonstrated that:(1)Alkali lignin was degraded after the plasma processing.The original groups were destroyed,and the aromatic rings collected abundant free radicals and oxygen-containing functional groups like hydroxyls,carbonyls,carboxyls and acyls were introduced into increase the reaction activity of lignin significantly.(2)The introduction of alkali lignin decreased the free formaldehyde content and increased bonding strength and toughness of the prepared phenol formaldehyde resin,especially after the introduction of lignin treated with plasma.(3)The introduction of alkali lignin led to high curing temperature for the prepared phenol formaldehyde resin,but that was reduced by the plasma processed alkali lignin.(4)The introduction of alkali lignin could also increase thermal stability of phenol formaldehyde resin,but that was modified by plasma processed alkali lignin was better than the unprocessed lignin.Based on the results,the plasma processed lignin was used to modify phenol formaldehyde resin,which could increase the strength and toughness of phenol formaldehyde resin significantly.
基金Supported by the National Natural Science Foundation of China (21061006) the Research of Natural Science and Technology Foundation of Guizhou Province ([2010]2006) the Graduate Scientific Innovation Project of Education Department of Guangxi Autonomous Region (1059330901009)
文摘Mesoporous aluminum-doped titanium dioxide(Al-TiO2) materials with high specific surface areas were prepared via a solid-state reaction route.The properties of these materials were characterized by X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),energy dispersive spectroscopy(EDS),N2 absorption-desorption,ultraviolet visible light spectroscopy(UV-Vis) and electrochemical spectroscopy.The results show that the mesoporous structure of the product with ethanol is composed of anatase laced crystal walls with amorphous grain boundaries formed gradually by degradation.Compared with those without ethanol,these samples possess larger crystallite size since ethanol decreases the pore size at higher temperature.With the increase of ethanol amount,however,the crystallite size will grow.The amorphous grain boundaries in the mesoporous material,with a large impedance and low incidental cyclic potential,are difficult to effectively degrade and the phase transformation temperature is changed from 500 to 550℃.The growth rate of Al-TiO2 crystallites that obeys the quadratic polynomial equation may be controlled.
基金Supported by Science and Technology Cooperation Plan of Guizhou Province(LH20157758)
文摘The Ecological Footprint and Development Capacity Model were used to analyze the ecological environment development capability of the Qingshui River Basin from 2000 to 2015. On this basis,the ecological environment development capacity of the Qingshui River Basin from 2016 to 2020 was dynamically predicted using the GM( 1,1) model. The results showed that the Qingshui River Basin has a strong capacity for sustainable development of the ecological environment,but it is increasingly stressed by the ecological carrying capacity. The potential unsustainability of the ecological environment is facing severe challenges. In the next 5 years,the development capacity of the ecological environment will show a growth trend,but the increase is not large,reflecting the limited development potential. Its capacity for sustainable development needs to be improved.
文摘In this paper, we study the global and pullback attractors for a strongly damped wave equation with delays when the force term belongs to different space. The results following from the solution generate a compact set.