Showing papers in "Journal of Chinese Electron Microscopy Society in 2006"

Observation of silicon cells on the leave surface in different varieties of rices

Abstract: The morphology of silicon cells on leave surface in eight varieties of rice was observed by using scanning electron microscopy,and the content of silicon was detected by using energy dispersive X-ray spectrum.The results showed that there existed differences in the morphology of silicon cells and content of silicon among different varieties.Furthermore,high number and larger volume of silicon cells and higher content of silicon were found on the blade surface of the autotetraploid varieties than those in the diploid varieties.Among the autotetraploid rices,Aijiaonante-4x was the largest in the silicon cell with 301.40μm~2,and the highest in the content of silicon with 32.77 wt.%;Guanglu'No.4 was the second in the silicon cell with 192.50μm~2 as well as in the content of silicon with 25.80 wt.%.There were eight pieces of silicon papilla in the two autotetraploid rices,which was twice as that in the diploid rice.These two autotetraploid varieties possessed straighter stems,better ventilation under leaves,higher lodging-resistance and insect-resistance in comparison with the varieties with smaller volume of silicon cells and lower content of silicon,such as Linglun,P23,L202,D27F2,Huajingxian No.74 and E5 which was not as good in these aspects.The results here indicated that the size and the content of silicon were associated with the lodging-resistance and insect-resistance and it may be considered as an important qualification for future breeding.

Structure and property of montmorillnate/natural rubber nano-composite prepared by natural rubber fresh latex

Abstract: The micro-and nano-montmorillnates were prepared by multi-solvents dispersing method and mixed with natural rubber fresh latex to make montmorillnate /natural rubber composite.The structures of the montmorillnate and the composites were studied by using SEM and the physics-mechanical properties of the composites were determined.The results show that the montmorillnate can be exfoliated into micro-and nano-laminas with the size of 100nm～200nm by the multi-solvents dispersing method.When the content of the montmorillnate was 7%,500% modulus of the composite increased to 11.22MPa and the contrast was 6.96MPa.The tensile strength of the composite with 2% montmorillnate enhanced to 21.01MPa and the contrast was 17.71MPa.The tensile strength of the composite contained 7% montmorillnate reached to 23.56MPa.With the increase of the content of the montmorillnate,the elongation at break of the composites decreased slowly while the composites kept high elastic.These results indicates that natural rubber fresh latex can be mixed with montmorillnates to prepare high performance natural rubber composite.

Study on the powder imaging method of atomic force microscopy

Abstract: In this article,a method on powder sample imaging of atomic force microscopy was presented.The powder sample was wetted up by pure water and placed in the air,and it was put into the atomic force microscope to be scanned after pure water was vaporized till there was only molecular binding water on the powder sample surface.With the analysis of the experimental process,we found that the problem of adhesion of the particles to the tip when using AFM to scan the sample's surface was solved through molecular binding water neutralized the residual charges on the surface of the particles.And the difficulty of the instability of the particles when the scanning process was going on was conquered by molecular binding water and capillary water which existed in the interspaces of the particles and made them band together hard.The powder sample morphologies obtained were clear and genuine.The experimental results indicated this method was easy but feasible and could be applied widely.Furthermore,a new and complex scanning circumstance of AFM was occured in this method,in which the tip vibrated in the air but the scanning sample was in water.This concept of complex scanning circumstance is worth more investigation and generalizing.

Study on single CNT's accurate assembly and electrical contact for fabricating nanoelectronic device

Abstract: Nowadays,nanoeletronic device based on single carbon nanotube(CNT) attracts much attention and many research works have been done on its fabrication,one of the key technical problems is how to realize accurate assembly and electrical contact between single CNT and microelectrodeAn AC dieletrophoresis and AFM based nanomanipulation technology with real-time force/visual feedback combining coarse and accurate positioning was introducedThe assembly and electric properties measurement of single MWCNT verified the effectiveness of this method,and thus provides a new method for assembling and fabricating nanoeletronic device based on single nanotube,nanowire,etc

Morphological studies on the location and classifying of chemoreceptors on the larva of Ostrinia furnacalis Guenée

Abstract: The chemoreceptors on antennae and mouthparts of the larva of Ostrinia furnacalis Guenee were observed using scanning electron microscopy.Two kinds of chemoreceptors on antennae of the larva were six sensilla basiconica on the second and third segments respectively,and one sensilla styloconicum on the third segment of the antennae.The maxillary palpus of mouthparts appendages owned eight sensilla basiconica chemoreceptors array 3-2-2-1,and its strumae owning one lateral sensilla styloconicum,one medial sensilla styloconicum and one sensilla basiconica.There were two sensilla basiconica chemoreceptors on the second and third segments of labial palpus.The antenna of larva Ostrinia furnacalis owned few chemoreceptors,which were mainly sensilla basiconica and sensilla styloconicum.The mouthparts appendages had a variety of chemoreceptors,which were mainly sensilla basiconica,lateral sensilla styloconicum and medial sensilla styloconicum.

Preparation and characterization of Mn-Zn ferrite magnetic nanoparticles for tumor hyperthermia

Abstract: With the sulfate as the materials and NaOH as precipitator,Mn-Zn ferrite nanoparticles composed of different chemical components were prepared and characterizated by X-ray diffraction(XRD)、transmission electron microscopy(TEM) and the heat analysis system.Besides,the heat effect was studied under given room temperature 20℃ and 200kHz alternating magnetic field in vitro.The results show that the prepared Mn_xZn_(1-x)Fe_2O_4 nanoparticles were spinel Mn-Zn ferrite,global,average diameter of 50nm.The curie temperature of Mn_xZn_(1-x)Fe_2O_4 decreased with the increase of Zn~(2+).The Mn_xZn_(1-x)Fe_2O_4 nanoparticles had very distinct heat effect in a alternating magnetic field,and the speed of heating and the steady temperature increased with the increased of magnetic strength and the concentration of Mn_xZn_(1-x)Fe_2O_4 nanoparticles;decreased with the increased of Zn~(2+).They can rise to a steady temperature for tumor hyperthermia.The study gives a way for solving the problem of controlling and stabilizing temperature at tumor hyperthermia.

Introduction to Photoelectron Emission Microscopy: Principles and Applications

Abstract: In the past decade, photoelectron emission microscopy (PEEM) has undergone major instrument development and become commercially available PEEM probes photoelectrons in a high-contrast imaging technique that is sensitive to the surface electronic structure In this paper we illustrate the principles of PEEM and analyze important PEEM contrast mechanisms We briefly summarize the applications of PEEM to areas such as surface structure analysis, surface chemistry, magnetism, and semiconductor device characterization Two important new directions in PEEM development are multiphoton and time-resolved PEEM Multiphoton PEEM is capable of imaging materials with work functions greater than the incident photon energy, while time-resolved PEEM enables study of fast relaxation dynamics of surface intermediate states We discuss our recent progress on implementing femtosecond time-solved PEEM and multiphoton PEEM to investigate the silver nanostructured film coated on silicon The multiphoton images consist of some ''hot spots'' with far greater photonelectron intensity than is observed in single-photon derived images We surmise that this is due to the highly-selective excitation of surface localized plasmon of silver To illustrate the utility of PEEM, we also describe an in-situ thermal-induced structural phase transformation of CuZnAl shape memory alloy

Design and research of phase imaging-mode atomic force microscopy

Abstract: Phase Imaging is a newly developed detecting method of atomic force microscopy which can provide more nanoscale information of sample surface.In this paper,a new phase detect circuitry for atomic force microscope has been developed.The phase images and simultaneous topographies acquired by this circuit were presented.

Dynamical changes of ultrastructure of chloroplasts and polysaccharide in wheat flag leaf during different stages

Abstract: There are many precious studies on wheat flag leaf,but most have focused on physiological and biochemical characteristics,few studies have examined the dynamic changes of physiological and biochemical characteristics and structure of wheat flag leaf during different stages.In this paper,sequential changes in the number of mesophyll cells and ultrastructure of chloroplasts as well as subcellular location and content of polysaccharide in high-yield wheat flag leaves(Xiao Yan 81) before and after anthesis were investigated by means of light microscopy,transmission electron microscopy,ultraviolet spectrophotometer together with histochemical analysis.The results showed that the number of chloroplasts,the number of the thylakoid per granum and the degree of grana stacks increased steadily from anthesis stage and reached a peak at milk development stage followed by a dramatic increase.Similarly,the content of polysaccharide and sucrose reached the highest value at the milk-development stage and then decreased sharply afterwards.The results described here suggested that the ultrastructure of chloroplast characteristics and the content of polysaccharide are closely linked to the photosynthetic efficiency during different stages of wheat flag leaf development and these features can be used as an index for future breeding,providing strong theoretical evidence for field management.

Reconstruction of electron exit waves: basic theory and applications

Abstract: With the popularization of field emission gun transmission electron microscopes (FEG-TEM),the information limit and the point resolution become two key important parameters to characterize the resolution ability of the microscopesBecause of the oscillation characteristic of the contrast transfer function,the information between the point resolution and information limit in the high resolution images taken from the FEG-TEM is difficult to interpretReconstruction of electron exit waves from focal series of lattice images extends resolution to near/sub-angstrom values,corrects for dominant aberrations of the objective lens,and allows imaging the atomic structure of crystalline materials directlyThis has enabled us to directly record columns of the light elements carbon,nitrogen and oxygen with sub-angstrom resolutionThis technique establishes the basis of quantitative TEM

Comparative study of EDTA and its salts with Na、K、Mg on crystallization of calcium oxalate

Abstract: The effect of ethylenediaminetetraacetic acid(H_2EDTA) and its Na~+、K~+、Mg~(2+) salts on the crystallization of calcium oxalate(CaOxa) was investigated in silica gel with a double diffusion technique.H_2EDTA and all its salts could inhibit the aggregation of calcium oxalate monohydrate(COM),decrease the specific surface area of COM aggregates and induce the formation of calcium oxalate dihydrate(COD).The relative ability follows the order: MgEDTA K_2EDTA Na_2EDTA H_2EDTA.This result was dicussed in terms of mixed complexation equilibria,the pH value of solution,electrostatic interaction and adsorption efficiency.It demonstrated that MgEDTA might be beneficial to the prevention and cure of urinary stones.

Diagnosis of the multiple pathogen of broad bean yellow mosaic disease

Abstract: The multiple infecting pathogen were detected in a sample of yellow mosaic broad bean from Lishui,Zhejiang province,by transmission electron microscopy,ELISA and RT-PCR.The results showed that two kinds of virus were found in leaf sap negative stained with 2%PTA.One was filamentous virus particles with 73% lengths ranging from 600nm to 800nm.The other was spherical virus particles,about 26nm in average diameter.The pathological study revealed that the Ⅱtype cylindrical inclusions and the amorphous inclusions were appeared in cytoplasm of the infected cells,which is the pathological symptom of BYMV infecting.Mitochondrial aggregation and membranous proliferation were also found in the infected cells,which is the pathological symptom of BBWV 2 infecting.One of the viruses were positive reacted with BBWV 2 monoclonal antibody by ELISA experiment.There was 1.7kb special production in 1% gel electrophoresis after RT-PCR using universal primer of genus Potyvirus.Based on all the results above,suggested that the spherical virus were Broad bean wilt virus 2(BBWV 2) and the filamentous virus were Bean yellow mosaic virus(BYMV).They were multiple infecting.

Effect of Alternanthera philoxeroides on the ultrastructure of the ganglion & foot muscle of Oncomelania hupensis

Abstract: To study the mechanisms of molluscicide from Alternanthera philoxeroides snails,Oncomelania hupensis,were immersed in aqueous extract of Alternanthera philoxeroides or in dechlorinated water for 24h.Ultrastructure of the ganglion and foot muscle from the immersed snails were observed by transmission electron microscopy(TEM).Results of experiments demonstrated that after 24 h exposure to aqueous extract of Alternanthera philoxeroides,ganglioneures was evidently damaged,its pericellular membrane disappeared,nucleus were pycnosis,cell organs denatured and necrosized,secondary lysoome increased and nerve fiber broken, and in the meanwhile,nucleus of foot-muscle cells swelled and gap between cells broadened.These ultrastructural changes indicated that the aqueous extract of Alternanthera philoxeroides had an obviously destruction of ganglioneures and caused foot-muscle cells to denature and a hydrops in between cells.

Light and transmission electron microscopical observation of the liver structure of swordtail,Xiphophorus helleri

Abstract: The structure and ultrastructure of the liver in Xiphophorus helleri have been investigated using light and transmission electron microscopy.The result shows that,according to the electron density in hepatic cytoplasm,the hepatic cells can be divided into two types—"light cell"and "dark cell".The hepatocyte contained a nucleus.Pronounced nucleoli were observed in each nucleus.Rough endoplasmic reticulum,mitochondria,glycogen and lipid droplets were abundant in cytoplasm of hepatocytes.The bile cannaliculi was makeup by rosettes of hepatocytes.Hepatic sinusoid was formed by endothelial cell,fibroblasts,fat-storing cells and Kupffer's cells.The histological structure and ultrastructure of the liver of teleosts were discussed.

Structural differences in the mature endosperms of wheat with different quality

Abstract: The structural differences were observed in the mature endosperms of wheat varieties with different quality(strong-gluten Jinan 17,medium-gluten Yangmai 12 and weak gluten Yangmai 9)by scanning electron microscope(SEM).Results showed that Jinan 17 exhibited a dense layer of protein matrix,which enveloped and masked starch grains.It was found that low amounts of protein matris was associated with starch grains of Yangmai 12,and the endosperm structure of it was looser.Yangmai 9 was found to be a low degree of starch-protein binding.The large and small starch grains were also isolated by the alkali method and differential sedimentation from wheat varieties.Under SEM there were no detectable differences in the granule morphology,but the average diameters and proportion(wt.%) of large and small starch grains indicated differences among varieties.

Preparation and characterization of TiO_2 hollow microspheres

Abstract: The TiO_2 powder catalyst is difficult to be recovered for use which seriously limits its application.In this paper the TiO_2 sol was prepared by a sol-gel method using Ti(OBu)_4 as precursor,then the TiO_2 sol was added dropwise onto the pre-prepared ion exchange resins.After filtration and drying,the coreshell TiO_2/ion exchange resin composite microspheres were produced.The TiO_2/ion exhange resin composite microspheres were heated in an furnance at the temperature of 470℃ for 6h and at the temperature of 550℃ for 2h in order to remove the ion exchange resins,and then the porous TiO_2 microspheres were obtained.The products were characterized by optical microscope、SEM、EDS、XRD and N_2 adsorption techniques.The results showed that the diameter of microspheres were 300μm～500μm,and the BET surface area was 38.27m~2/g.The contents of anatase and rutile in the surface TiO_2 nanocrystals of the microspheres were about 80% and 20%,respectively.And the size of the TiO_2 nanocrystals was 30nm～50nm,most of them were spheres and small prisms.Based on the porous and hollow structure characterization of the microspheres,the TiO_2 microspheres would be expected to application in photocatalyse repeatedly.The experiment of photocatalytic degradation in Rhodamine B showed that the microspheres had high photocatalytic activity.

Quantitative description of the tortuosity of multi-walled carbon nanotubes by electron microscopy images

Abstract: The morphologies of carbon nanotubes(CNTs) are influenced by the methods of preparation and post-treated processes.In order to describe the morphological features of CNTs clearly,a method to quantitatively characterize the tortuosity of CNTs has been developed in this work by introducing two parameters: Tortuosity Factor(TF) and Calculating Scale(CS).These two parameters were used to analyze the images of Multi-Walled Carbon Nanotubes(MWCNTs) taken by the High Resolution Transmission Electron Microscopy(HRTEM) and the Scan Electron Microscopy(SEM).Using this method,three different kinds of MWCNTs were characterized,which were MWCNTs prepared by the catalytic chemical vapor deposition(CCVD) method in a nano-agglomerate fluidized-bed reactor(NAFBR),MWCNTs embedded in electrospun Poly Ethylene Oxide(PEO) nanofibers and well-aligned long MWCNTs prepared by floating CVD method,respectively.The results show that the three types of MWCNTs possess different TFs with same CS.The information is very important for instructing the preparation and post-treated processes of MWCNTs as well as for preparing MWCNTs/polymer composites.

Numerical simulation of pyramdal tip entirely coated with Ag film with focusing spot at nanometer scale

Abstract: The electric field distribution for pyramdial tip entirely coated with Ag film was simulated with(FD)~2TD method.The results indicate that the tip of this geometry can not only produce focusing spot at nanometer scale but also engender enormous field enhancement under the excitation of plane wave from the base of pyramidal tip.

Nanomanipulation aided AFM localization observation

Abstract: Nowadays,localization observation is still a difficult work for atomic force microscope(AFM) research,especially when absence of mark on the surface.Sometimes,the mark for localization was covered by the film on substrate,which raises the mark lack.In present work,a solution based on AFM manipulation was introduced to discover the covered mark for precise localization.The contact mode AFM could be used to "sweep" the slipcover and expose the mark.As an example,in situ observation of the bovine serum albumin(BSA) adsorption film on highly ordered pyrolytic graphite(HOPG) was described.When the marks,atomic steps on HOPG,were covered by BSA molecules,contact mode AFM could "sweep" the BSA molecules away.Then,the exposed atomic steps were used as mark for precise location.The "clean" area could be adjusted by setting some parameters,such as setpoint,scan size,scan rate,scan sample/lines,offset,and scan duration.

Current-voltage characteristics of single zinc oxide nanobelt/gold electrodes system

Abstract: E-beam lithography and vacuum evaporating methods were used to form four gold electrodes on single ZnO nanoblt and SiO_2/Si wafer.Four terminal electrical transport measurements were conducted on semiconducting nanobelt and three distinct I-V characteristics were observed.Deciding to metal-semiconductor(MS) contact,asymmetric valve current type curve was corresponding to a much lower MS contact resistance,and the curve did not change largely under ambient and vacuum testing condition;at larger contact resistance,almost rectifying and almost linear curves are observed which was corresponding to ambient and vacuum condition respectively.It appeared that the adsorption of oxygen on ZnO naobelt/Au electrodes system played a key role to the semiconducting nanobelt.