This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture. The surface ...This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture. The surface morphology and the structure of the fabricated films were characterized by using scanning electron microscopes and Raman spectroscopy, respectively. The stable field emission properties with a low threshold field of 5V/μm corresponding to a current density of about 1μA/cm^2 and a current density of 3.2mA/cm^2 at an electric field of 10V/μm were obtained from the carbon film deposited at CH4 concentration of 8%. The mechanism that the threshold field decreased with the increase of the CH4 concentration and the high emission current appeared at the high CH4 concentration was explained by using the Fowler-Nordheim theory.展开更多
The excessive staminate catkin thinning （emasculation） of proterandrous walnut is an important management measure for improving yield. To improve the excessive staminate catkin thinning efficiency, the model of quad...The excessive staminate catkin thinning （emasculation） of proterandrous walnut is an important management measure for improving yield. To improve the excessive staminate catkin thinning efficiency, the model of quadratic polynomial regression equation and BP artificial neural network was developed. The effects of ethephon, gibberel in and mepiquat on shedding rate of staminate catkin of pro-terandrous walnut were investigated by modeling field test. Based on the modeling test results, the excessive staminate catkin thinning model of quadratic polynomial regression equation and BP artificial neural network was established, and it was validated by field test next year. The test data were divided into training set, vali-dation set and test set. The total 20 sets of data obtained from the modeling field test were randomly divided into training set （17） and validation set （3） by central composite design （quadric rotational regression test design）, and the data obtained from the next-year field test were divided into the test set. The topological struc-ture of BP artificial neural network was 3-5-1. The results showed that the pre-diction errors of BP neural network for samples from the validation set were 1.355 0%, 0.429 1% and 0.353 8%, respectively; the difference between the predicted value by the BP neural network and validated value by field test was 2.04%, and the difference between the predicted value by the regression equation and validated value by field test was 3.12%; the prediction accuracy of BP neural network was over 1.0% higher than that of regression equation. The effective combination of quadratic polynomial stepwise regression and BP artificial neural network wil not only help to determine the effect of independent parameter but also improve the prediction accuracy.展开更多
Liquid crystalline elastomers(LCEs)have been utilized as an important class of smart actuator materials.However,the modest actuation mechanical and robustness performances remain a challenge.Inspired by the specific s...Liquid crystalline elastomers(LCEs)have been utilized as an important class of smart actuator materials.However,the modest actuation mechanical and robustness performances remain a challenge.Inspired by the specific structures,well mechanical properties and physico-chemical characteristics of some natural plant fibers,a composite of thiol-acrylate main-chain LCE matrix incorporated with catkin fibers is designed and developed.The catkin fibers build a network as reinforcement phase,and demon-strate effective compatibility and integration property with the matrix,their high flexibility can be adapted to the large deforma-tional performance of LCE matrix.The prepared LCE composite demonstrates strong mechanical actuation properties.The mod-ulus and driving force triggered by the stimuli are obviously increased.The tensile strength and fatigue failure resistant prop-erty under high loadings and repeated cycles of thermal actua-tion or photothermal actuation are greatly enhanced.While the stimulus response deformation rate,phase transition temperature and liquid crystal phase structure of the LCE matrix,and so on,do not weaken or change.This work promotes the LCE materi-als’application potential and broadens the application value of natural plant fibers.展开更多
Sialic acids as terminal entities of larger glycans linked to proteins and lipids are involved in multiple different pathological and physiological processes.Structural characterisation of sialoglycoconjugates is requ...Sialic acids as terminal entities of larger glycans linked to proteins and lipids are involved in multiple different pathological and physiological processes.Structural characterisation of sialoglycoconjugates is required to understand their biological function.However,a comprehensive sialylation analysis of sialoglycoconjugates has remained challenges.In this study,we employ a natural biomaterial,poplar catkin derived from white poplar tree（Populus tomentosa Carr.）,to develop a novel capturing microtip for selective and efficient enrichment of sialoglycopeptides,without losses of sialic acid residues and water molecules from sialoglycopeptides.Scanning electron microscopy and Fourier-transform infrared spectroscopy analysis,along with Maule and Wiesner staining assays,indicated that the main components on the outer layer of the poplar catkin are syringyl and guaiacyl lignins which play a key role in enriching sialoglycopeptides from complex peptide mixture.展开更多
Questionnaire survey was taken,the plant-caused pollution in 4 typical cities including Beijing,Hefei,Chengdu and Guangzhou was studied.Differences of three kinds of plant-caused pollution such as pollen,flying hair a...Questionnaire survey was taken,the plant-caused pollution in 4 typical cities including Beijing,Hefei,Chengdu and Guangzhou was studied.Differences of three kinds of plant-caused pollution such as pollen,flying hair and catkin,and smell between different cities and different people were analyzed.The results are as follows:the plant-caused pollution has obviously regional distribution features.The rate of plant-caused pollution is 5.72% in Beijing,0.59% in Chengdu,2.12% in Hefei and 2.11% in Guangzhou.The order of the number of three kinds of plant-caused pollution allergen is pollen>flying hair and catkin>smell.The allergen caused by pollen and flying hair and catkin gathers largely in March to June.The allergen caused by smell gathers largely in summer.The whole condition of the allergen is female>male,and most of them are 20 to 50 years old.The results provide basis for the further research,and are also helpful for prevention of plant-caused pollution in urban area.展开更多
文摘This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture. The surface morphology and the structure of the fabricated films were characterized by using scanning electron microscopes and Raman spectroscopy, respectively. The stable field emission properties with a low threshold field of 5V/μm corresponding to a current density of about 1μA/cm^2 and a current density of 3.2mA/cm^2 at an electric field of 10V/μm were obtained from the carbon film deposited at CH4 concentration of 8%. The mechanism that the threshold field decreased with the increase of the CH4 concentration and the high emission current appeared at the high CH4 concentration was explained by using the Fowler-Nordheim theory.
基金Supported by Key Science and Technology Program of Shanxi Province,China(002023)~~
文摘The excessive staminate catkin thinning （emasculation） of proterandrous walnut is an important management measure for improving yield. To improve the excessive staminate catkin thinning efficiency, the model of quadratic polynomial regression equation and BP artificial neural network was developed. The effects of ethephon, gibberel in and mepiquat on shedding rate of staminate catkin of pro-terandrous walnut were investigated by modeling field test. Based on the modeling test results, the excessive staminate catkin thinning model of quadratic polynomial regression equation and BP artificial neural network was established, and it was validated by field test next year. The test data were divided into training set, vali-dation set and test set. The total 20 sets of data obtained from the modeling field test were randomly divided into training set （17） and validation set （3） by central composite design （quadric rotational regression test design）, and the data obtained from the next-year field test were divided into the test set. The topological struc-ture of BP artificial neural network was 3-5-1. The results showed that the pre-diction errors of BP neural network for samples from the validation set were 1.355 0%, 0.429 1% and 0.353 8%, respectively; the difference between the predicted value by the BP neural network and validated value by field test was 2.04%, and the difference between the predicted value by the regression equation and validated value by field test was 3.12%; the prediction accuracy of BP neural network was over 1.0% higher than that of regression equation. The effective combination of quadratic polynomial stepwise regression and BP artificial neural network wil not only help to determine the effect of independent parameter but also improve the prediction accuracy.
基金This work was supported by the the Open Research Fund Program of Institute of regulatory science,Beijing Technology and Business University[CRS-2020-01]the Natural Science Foundation of Heilongjiang Province of China[LH2020E106].
文摘Liquid crystalline elastomers(LCEs)have been utilized as an important class of smart actuator materials.However,the modest actuation mechanical and robustness performances remain a challenge.Inspired by the specific structures,well mechanical properties and physico-chemical characteristics of some natural plant fibers,a composite of thiol-acrylate main-chain LCE matrix incorporated with catkin fibers is designed and developed.The catkin fibers build a network as reinforcement phase,and demon-strate effective compatibility and integration property with the matrix,their high flexibility can be adapted to the large deforma-tional performance of LCE matrix.The prepared LCE composite demonstrates strong mechanical actuation properties.The mod-ulus and driving force triggered by the stimuli are obviously increased.The tensile strength and fatigue failure resistant prop-erty under high loadings and repeated cycles of thermal actua-tion or photothermal actuation are greatly enhanced.While the stimulus response deformation rate,phase transition temperature and liquid crystal phase structure of the LCE matrix,and so on,do not weaken or change.This work promotes the LCE materi-als’application potential and broadens the application value of natural plant fibers.
基金supported by the National Natural Science Foundation of China(No.21575164)to Z.L
文摘Sialic acids as terminal entities of larger glycans linked to proteins and lipids are involved in multiple different pathological and physiological processes.Structural characterisation of sialoglycoconjugates is required to understand their biological function.However,a comprehensive sialylation analysis of sialoglycoconjugates has remained challenges.In this study,we employ a natural biomaterial,poplar catkin derived from white poplar tree（Populus tomentosa Carr.）,to develop a novel capturing microtip for selective and efficient enrichment of sialoglycopeptides,without losses of sialic acid residues and water molecules from sialoglycopeptides.Scanning electron microscopy and Fourier-transform infrared spectroscopy analysis,along with Maule and Wiesner staining assays,indicated that the main components on the outer layer of the poplar catkin are syringyl and guaiacyl lignins which play a key role in enriching sialoglycopeptides from complex peptide mixture.
文摘Questionnaire survey was taken,the plant-caused pollution in 4 typical cities including Beijing,Hefei,Chengdu and Guangzhou was studied.Differences of three kinds of plant-caused pollution such as pollen,flying hair and catkin,and smell between different cities and different people were analyzed.The results are as follows:the plant-caused pollution has obviously regional distribution features.The rate of plant-caused pollution is 5.72% in Beijing,0.59% in Chengdu,2.12% in Hefei and 2.11% in Guangzhou.The order of the number of three kinds of plant-caused pollution allergen is pollen>flying hair and catkin>smell.The allergen caused by pollen and flying hair and catkin gathers largely in March to June.The allergen caused by smell gathers largely in summer.The whole condition of the allergen is female>male,and most of them are 20 to 50 years old.The results provide basis for the further research,and are also helpful for prevention of plant-caused pollution in urban area.
