[ Objective] The research aimed to explore the manufacturing methods of scanning electron microscope (SEM) and transmission electron microscopy (TEM) for oocyte and provide technical support for related research. ...[ Objective] The research aimed to explore the manufacturing methods of scanning electron microscope (SEM) and transmission electron microscopy (TEM) for oocyte and provide technical support for related research. [ Method] Based on GV-and MII-stage oocytes, samples of SEM and TEM were prepared respectively, then ultrastructure changes were observed. [ Result] The results showed that the method needed few samples, keep intact cell morphology and can see clear ultrastructure. [Conclusion] The method is suitable for ultrastructural observation of oocyte.展开更多
Polycarbonate plastics containing bisphenol A (BPA) used to manufacture drinking water bottles. Kurdistan region in northern Iraq is a developed area with increased pollution from plastic bottles. Trace amounts of BPA...Polycarbonate plastics containing bisphenol A (BPA) used to manufacture drinking water bottles. Kurdistan region in northern Iraq is a developed area with increased pollution from plastic bottles. Trace amounts of BPA have been detected in bottled water samples. The absorption of BPA was measured with HPLC using a vertical cultivation system with Bulbs of the Allium Cepa plant planted in these plastic bottles with monitored growth. Vertical cultivation was found to have a low level of BPA in the plant cells, making it a safe cultivation method under specific climate conditions. The mean concentration of BPA in vertical cultivation is 0.19 ug/ml (3.8 ng for a 20 uL injection), and the Limit of Quantification (LOQ) is 0.63 ug/ml (12.7 ng for 20 uL injection). While Scanning Electron Microscope (SEM) shows that the concentrations are relatively low in water samples stored at room temperature compared to those exposed to direct sunlight (40°C) and water bottle samples stored at (-4°C), The correlation coefficients were found to be good (0.9992). SEM is used for plastic bottle samples stored at different temperatures. The images identify compound decay and explore the morphology of BPA in manufactured plastic materials.展开更多
In th is study, th e m eso-failure m ech an ism an d fracture surface o f Jinping m arble w ere investigated bym ean s o f scanning electro n m icroscope (SEM) w ith ben d in g loading system and laser-scanner equip...In th is study, th e m eso-failure m ech an ism an d fracture surface o f Jinping m arble w ere investigated bym ean s o f scanning electro n m icroscope (SEM) w ith ben d in g loading system and laser-scanner equipment. The Y antang an d B aishan m arbles specim ens from Jinping II hyd ro p o w er sta tio n w ere used. Testresu lts show th a t th e fracture to u g h n ess and m echanical behaviors o f Y antang m arble w ere basicallyh ig h er th a n th o se o f Baishan m arble. This is m ainly d u e to th e fact th a t Baishan m arble co n tain s a largep ercen tag e o f d o lom ite an d m in o r mica. Crack pro p ag atio n p a th and fracture m orphology in d icated th a tth e d irection o f ten sile stress has a significant effect on th e m echanical behaviors an d fracture toughnesso f B aishan m arble. For Yantang an d B aishan m arbles, a large n u m b e r o f m icrocracks a ro u n d th e m aincrack tip w ere observed w h e n th e directio n o f ten sile stress w as parallel to th e bed d in g plane.C onversely, few m icrocracks o ccurred w h e n th e directio n o f ten sile stress w as p erp en d icu lar to th ebed d in g plane. The presen ce o f a large n u m b e r o f m icrocracks a t th e m ain crack tip d ecreased th e globalfracture to u g h n ess o f m arble. The results o f th re e -p o in t ben d in g te sts show ed th a t th e average bearingcapacity o f intact m arble is 3.4 tim es th e notch ed m arble, b u t th e ductility p ro p e rty o f th e defectivem arble afte r p eak load is b e tte r th a n th a t o f th e intact m arble. H ence, large d efo rm atio n m ay beg en erated before failure o f in tact m arbles a t Jinping II h y d ro p o w er station. The fractal d im en sio n o ffracture surface w as also calculated by th e cube covering m eth o d . O bservational resu lt show ed th a t th elargest fractal dim en sio n o f Y antang m arble is cap tu red w h e n th e directio n o f ten sile stress is parallel toth e bedding plane. H ow ever, th e fractal d im en sio n o f fracture surface o f Yantang an d Baishan m arblesw ith ten sile stress vertical to th e bed d in g plane is relatively sm all. The fractal d im en sio n can also be usedto characterize th e ro ughness o f fracture surface o f rock m aterials.展开更多
We detailed the valve morphology of five new species of diatom genus Nupela from wetwall communities in Yunnan Province,China,with light and scanning electron microscope.The five new species demonstrate great variabil...We detailed the valve morphology of five new species of diatom genus Nupela from wetwall communities in Yunnan Province,China,with light and scanning electron microscope.The five new species demonstrate great variability within the genus,as three of them are biraphid and two are monoraphid.In addition,variation was noted in the structure of internal proximal raphe ends,with some species having anchor-shaped ends and other species have hooked ends.The genus Nupela has grown considerably in 30years since it was first proposed,going from a monotypic genus to over 85 taxa.Diagnosis of the genus is based on the presence of an external covering over the areolae.We discussed the systematic placement of Nupela within the naviculoid diatoms.Yunnan Province appears to harbor many endemic diatom taxa,and many regions of the province have yet to be studied.展开更多
Non-pillar mining,top-coal caving and protected coal seam mining are the most popular mining methods in coal exploitation,and the different mining layouts will change the stress state and failure mechanism of coal in ...Non-pillar mining,top-coal caving and protected coal seam mining are the most popular mining methods in coal exploitation,and the different mining layouts will change the stress state and failure mechanism of coal in front of the working face.In this paper,mining-induced mechanical behaviors under three mining layouts have been simulated in the laboratory to investigate the effects of mining layouts on the deformation and strength of coal.Furthermore,the coal failure mechanism under different mining layouts is analyzed microscopically.The experimental results indicate that the stage characteristics of the coal deformation are obvious.Under the serial action of non-pillar mining,top-coal caving and protected coal seam mining layouts,the values of radial deformation,volume strain and Poisson's ratio increase,while the peak strength and deformation modulus decrease at the same buried depth,and the peak strength under non-pillar mining,top-coal caving and protected coal seam mining is about 3.0,2.5 and 2.0 times of the initial confining pressure,respectively.The results also indicate that the trend of the coal deformation decreases with the increase of the buried depth under the same mining layout,while the strength and deformation modulus increase,and the failure mechanism under three mining layouts is dominated with shear/tensile failure.展开更多
The morphology and toxicity of Pseudo-nitzschia strain PP0201-01, isolated near the estuary of Changjiang (Yangtze) River in Year 2002 and tentatively identified as Pseudo-nitzschia pungens, were studied. The strain w...The morphology and toxicity of Pseudo-nitzschia strain PP0201-01, isolated near the estuary of Changjiang (Yangtze) River in Year 2002 and tentatively identified as Pseudo-nitzschia pungens, were studied. The strain was identified morphologically as P. pungens using scanning electronic microscope (SEM). The ana- lytical results of LC-PDA (liquid chromatography with photodiode array detector), LC-MS (liquid chromatogra- phy with mass detector), and the toxicity data from mouse bioassay, showed that no domoic acid was produced by the strain. However, the mechanism of domoic acid production by Pseudo-nitzschia species is complicated. More works are needed to assess the toxic species and to evaluate the potential risk of amnesic shellfish poison- ing (ASP) in China.展开更多
The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray...The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray diffractometer (XRD). All the mineral assemblages are similar in these landslides. The main minerals are montmorillonite, illite, kaolinite, chlorite, quartz and feldspar. There are two kinds of surface microtexture in the slipping zone soil, i.e., linear scratches and arcuate scratches. Based on analyses of the changes of the microtextures, one can obtain information about the number, directions and stages of landslide movements. The authors have also studied the mechanism of landslide formation, evaluated the stability of landslides and revival possibility of ancient landslides and forecasted the activity of similar landslides in different districts. The surface microtexture features of stable landslides and mobile landslides are summarized and it is concluded that the existence of filamentous bacteria may result in or increase movements of landslides.展开更多
Non Pt based metals and alloys as electrode materials for methyl alcohol fuel cells have been investigated w ith an aim of finding high electrocatalytic surface property for the faster electrode reactions.Electrodes w...Non Pt based metals and alloys as electrode materials for methyl alcohol fuel cells have been investigated w ith an aim of finding high electrocatalytic surface property for the faster electrode reactions.Electrodes w ere fabricated by electrodeposition on pure Al foil,from an electrolyte of Ni,Co,Fe salts.The optimum condition of electrodeposition w ere found out by a series of experiments,varying the chemistry of the electrolyte,pH valve,temperature,current and cell potential.Polarization study of the coated Ni-Co or Ni-CoFe alloy on pure Al w as found to exhibit high exchange current density,indicating an improved electro catalytic surface w ith faster charge-discharge reactions at anode and cathode and low overvoltage.Electrochemical impedance studies on coated and uncoated surface clearly show ed that the polarization resistance and impedance w ere decreased by Ni-Co or Ni-Co-Fe coating.X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDX)and atomic absorption spectroscopy(AAS)studies confirmed the presence of alloying elements and constituents of the alloy.The morphology of the deposits from scanning electron microscope(SEM)images indicated that the electrode surface w as a three dimensional space w hich increased the effective surface area for the electrode reactions to take place.展开更多
Cracked straight-through Brazilian disc(CSTBD) samples prepared using two rock materials were used for thermal treatment from room temperature to 700℃. Uniaxial splitting experiments were performed using an automatic...Cracked straight-through Brazilian disc(CSTBD) samples prepared using two rock materials were used for thermal treatment from room temperature to 700℃. Uniaxial splitting experiments were performed using an automatic electro-hydraulic servo press to study the evolution laws of physical and fracture properties of different deep rock materials under high-temperature geological conditions. The fracture characteristics were measured using an industrial camera and digital image correlation technology to analyze the effect of high temperature on fracture properties and failure modes of the CSTBD samples after different thermal treatments. The micro-damage properties of green sandstone and granite materials were obtained using a scanning electron microscope(SEM). The following conclusions were drawn from the test results:(1) With the increasing temperature, the fracture characteristics of green sandstone and granite change from brittle fracture to plasticity fracture, the longitudinal wave velocity of granite decreases sharply at 600℃, and the damage factor reaches 0.8748 at 700℃.(2) The fracture toughness of green sandstone and granite decreases with increasing temperature;however, the decreasing range of granite is larger than that of green sandstone.(3) As the temperature increases, the fracture morphologies of green sandstone and granite materials become rougher, whereas thermal damage cracks of granite and intergranular fractures inside sandstone as well as pores of sandstone increase.(4) The crack tip opening displacement and peak strain corresponding to peak load increase with the temperature.展开更多
In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosi...In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40 Cr Mn Si B steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thickness and the number of the circumferential divisions. The results show that as the tempering temperature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.展开更多
The adherence strength between the metal and the inorganic coating can be greatly increased by mill addition of Li2Ni8O10. The interface structure between metal and the inorganic coating with excellent adherence has b...The adherence strength between the metal and the inorganic coating can be greatly increased by mill addition of Li2Ni8O10. The interface structure between metal and the inorganic coating with excellent adherence has been studied by investigating the chemical composition and the microstrncture as well as elements valence bond on the interface with the help of scanning electron microscope (SEM), electron microprobe, and Auger elctron spectroscope (AES). The results show that there is a non-stoichiometrieal transitional layer on the interface between metal and the inorganic coating with excellent adherence, the adherence between metal and the non-stoichiometrical transitional layer is achieved by the metallic bond and the adherence between the non- stoichiometrical transitional layer and the inorganic coating is produced by ionic and covalent bond. The non-stoichiometrical transitional layer results in the strong adherence.展开更多
There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and ...There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and foundations, and tunnel walls, undergo both static and cyclic loading caused by drilling and blasting, and vehicle-induced vibrations. This type of loading often causes rock to fail at a lower than its static strength due to the effect of rock fatigue. A series of laboratory diametrical compression tests was performed on Brisbane tuff disc specimens to investigate their mode-I fracture toughness response to static and cyclic loading, as a function of the applied load. Both the static and cyclic loading tests were carried out on CCNBD (cracked chevron notched Brazilian disc) rock specimens. In the tests described herein, the reduction in fracture toughness under dynamic cyclic loading was found to be up to 48% of the static fracture toughness. Contrary to the static tests, the cyclic tests produced much more crushed material in front of the tip of the chevron notched crack.展开更多
In order to investigate the influence of natural defect on the fatigue behavior of 5A06/7A05 dissimilar aluminum alloys welding joint,fatigue tests of two types of specimens with and without defects were carried out s...In order to investigate the influence of natural defect on the fatigue behavior of 5A06/7A05 dissimilar aluminum alloys welding joint,fatigue tests of two types of specimens with and without defects were carried out systematically under stress amplitude control conditions (stress ratio R=0.1) at normal temperature in laboratory air condition.Furthermore,a new parameter,i e,fatigue defect effect factor (FDEF) was introduced to assess the effect of defect on fatigue strength.The fatigue failure analysis was conducted as well to compare the fatigue and fracture behavior of the two types of specimens.The results show that:(1) natural defects have a strong effect on the fatigue lives of welding joint,and the differences between the specimens with and without defects can reach 80 times under a same theoretical net sectional stress;(2) the FDEF parameter introduced is effective to deal with the defect effect,and the FDEF decreases along with the increase of fatigue life.The mean relative error between the experimental data and predicted fatigue strength based on the FDEF is 10.2%;(3) the macro fracture of both types of specimens have three typical zones,i e,fatigue source zone,crack propagation zone and final fracture zone,while there are more than one fatigue sources for specimens with natural defects.The overall pattern of crack propagation zone and fracture zone are quite similar,but the morphologies are different in details.展开更多
Polyhydroxyalkanoates(PHAs)were synthesized in activated sludge using three types of carbon sources(sodium acetate,sodium propionate and sodium butyrate),and their characterization were studied.It was shown that t...Polyhydroxyalkanoates(PHAs)were synthesized in activated sludge using three types of carbon sources(sodium acetate,sodium propionate and sodium butyrate),and their characterization were studied.It was shown that the content of PHA synthesized by microorganisms in activated sludge were different.The biggest synthetic amount up to 36.7% of VSS was obtained when sodium acetate was used as carbon source.The polymer yield was lower when using sodium propionate as the carbon source than when using others,with25.1% of VSS,while resulted in an increase of hydroxyvalerate(HV)units produced.The structure and thermal properties of extracted biopolymers were analyzed by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR)and themogravimetry(TG).展开更多
Electrochemical discharge machining is considered to be a hybrid machining process that combines with EDM and ECM (electro chemical machining), called ECDM. The material removal is based on two phenomena: electroch...Electrochemical discharge machining is considered to be a hybrid machining process that combines with EDM and ECM (electro chemical machining), called ECDM. The material removal is based on two phenomena: electrochemical dissolution of the material and thermal erosion of electrical discharges that occur between the cathode & anode electrodes. This process is better used for machining of non conducting materials efficiently. In this research paper shows that a brief literature review study of various measuring instruments used for analysis of various parameters of the electrochemical discharge machining process on various types of materials, tool material, input & output parameters such as surface roughness, surface texture, material removal, tool wear etc..展开更多
The Historical Wellesley Bridge,built by the Krishnaraja Wadiyar under the supervision of Dewan Purnaih across river Cauvery at Srirangapatna.Situation of bridge is got when heavy rainfall followed by heavy inflow fro...The Historical Wellesley Bridge,built by the Krishnaraja Wadiyar under the supervision of Dewan Purnaih across river Cauvery at Srirangapatna.Situation of bridge is got when heavy rainfall followed by heavy inflow from Cauvery Catchment area in Kodagu District.At present,the Government of Karnataka has taken measures to do the restoration works using the same previously used materials with slight changes.Hence,in the present investigation the authors are doing a case study on the above structure by testing the ingredients of the materials used for it and also by conducting Non-Destructive Test on the structure to know its strength before and after restoration.Based on the test results obtained,the authors will give a conclusion with respect to durability aspects.In addition to the above,the authors will test for few alternative materials i.e.,lime mortar with Cement(i.e.MM2 Grade Masonary mortar).Finally,from the obtained test results here the authors can suggest suitable material for the structures.展开更多
The antioxidant of seeds was carried out using extracts from methanol and Silver Nanoparticles from the spice. The SEM shows the shapes, dispersion and agglomeration of the sample, while the EDX confirms the SEM and t...The antioxidant of seeds was carried out using extracts from methanol and Silver Nanoparticles from the spice. The SEM shows the shapes, dispersion and agglomeration of the sample, while the EDX confirms the SEM and the presence of some compounds. The FT-IR reveals the AgNP<sub>s</sub> capping and reducing the particular biomolecule from the functional group for identification. Compounds found in the FT-IR seeds of Capsicum annum are Ag L (Silver iodide), C K (Cyanogen chloride), P K (Phenol). Monodora myristica are Mo L (Molybdenum), Ag L (Silver iodide), C K (Cyanogen chloride), P K (Phenol), Mg K (Magnesium). Piper guineense are Ag L (Silver iodide), Ci K (Potassium chloride), C K (Cyanogen chloride), P K (Phenol). The seeds show that the AgNP<sub>S</sub> of CA and MM has a better antioxidant activity than the methanol of CA and MM, while the PG methanol has a better activity than the AgNP<sub>S</sub> PG. The control (Catechin and Galic acid) has a slight overall better DPPH activity than the AgNP<sub>S</sub>. It is important to note that there is a concentration dependency in CA, MM AgNP<sub>S,</sub> PG methanol respectively. Notably, at CA methanol, the conc. at 125 was higher than the conc. at 250. Hence, there is need to create a great part in using plant samples for making tabulated or capsulated drugs for treatment of diseases and using plant silver nanoparticles to develop a healthy food/drug preservative package material “smart packaging” that will enhance shelf-life.展开更多
Observing the morphology of insulating specimen in scanning electron microscope(SEM)is of great significance for the nanoscale semiconductor devices and biological tissues.However,the charging effect will cause image ...Observing the morphology of insulating specimen in scanning electron microscope(SEM)is of great significance for the nanoscale semiconductor devices and biological tissues.However,the charging effect will cause image distortion and abnormal contrast when observing insulating specimen in SEM.A typical solution to this problem is using metal coating or water-removable conductive coating.Unfortunately,in both cases the surface of the specimen is covered by a thin layer of conductive material which hides the real surface morphology and is very difficult to be completely removed after imaging.Here we show a convenient,residue-free,and versatile method to observe real surface morphology of insulating specimen without charging effect in SEM with the help of a nanometer-thick film of super-aligned carbon nanotube(SACNT).This thin layer of SACNT film,like metal,can conduct the surface charge on insulating specimen through the sample stage to the ground,thus eliminating the charging effect.SACNT film can also be used as the conductive tape to carry and immobilize insulating powder or particles during SEM imaging.Different from the metal coating,SACNT film is transparent,so that the real microstructure of the insulating specimen surface can be observed.In addition,SACNT film can be easily attached to and peeled off from the surface of specimen without any residue.This convenient,residue-free,and versatile method can open up new possibilities in nondestructive SEM imaging of a wide variety of insulating materials,semiconductor devices,and biological tissues.展开更多
In this paper,we report upon our recent work aimed at improving and adapting machine learning algorithms to automatically classify nanoscience images acquired by the Scanning Electron Microscope(SEM).This is done by c...In this paper,we report upon our recent work aimed at improving and adapting machine learning algorithms to automatically classify nanoscience images acquired by the Scanning Electron Microscope(SEM).This is done by coupling supervised and unsupervised learning approaches.We first investigate supervised learning on a ten-category data set of images and compare the performance of the different models in terms of training accuracy.Then,we reduce the dimensionality of the features through autoencoders to perform unsupervised learning on a subset of images in a selected range of scales(from 1μm to 2μm).Finally,we compare different clustering methods to uncover intrinsic structures in the images.展开更多
The fabrication technique of micro/nano-scale speckle patterns with focused ion beam (FIB) system is studied for digital image correlation (DIC) measurement under a scanning electron microscope (SEM).The speckle patte...The fabrication technique of micro/nano-scale speckle patterns with focused ion beam (FIB) system is studied for digital image correlation (DIC) measurement under a scanning electron microscope (SEM).The speckle patterns are fabricated by directly etching the counterpart of the specimen to the black part of a template.Mean intensity gradient is used to evaluate the quality of these SEM images of speckle patterns fabricated based on different templates to select an optimum template.The pattern size depending on the displacement measurement sensitivity is adjusted by altering the magnification of FIB according to the relation curve of the etching size versus magnification.The influencing factors including etching time and ion beam current are discussed.Rigid body translation tests and rotation tests are carried out under SEM to verify the reliability of the fabricated speckle patterns.The calculated values are in good agreement with the imposed ones.展开更多
基金Supported by Natural Science Foundation of Jiangsu Province(Grant number:BK2008589)Shanghai Committee(Grant num-ber:2003 #14-1)~~
文摘[ Objective] The research aimed to explore the manufacturing methods of scanning electron microscope (SEM) and transmission electron microscopy (TEM) for oocyte and provide technical support for related research. [ Method] Based on GV-and MII-stage oocytes, samples of SEM and TEM were prepared respectively, then ultrastructure changes were observed. [ Result] The results showed that the method needed few samples, keep intact cell morphology and can see clear ultrastructure. [Conclusion] The method is suitable for ultrastructural observation of oocyte.
文摘Polycarbonate plastics containing bisphenol A (BPA) used to manufacture drinking water bottles. Kurdistan region in northern Iraq is a developed area with increased pollution from plastic bottles. Trace amounts of BPA have been detected in bottled water samples. The absorption of BPA was measured with HPLC using a vertical cultivation system with Bulbs of the Allium Cepa plant planted in these plastic bottles with monitored growth. Vertical cultivation was found to have a low level of BPA in the plant cells, making it a safe cultivation method under specific climate conditions. The mean concentration of BPA in vertical cultivation is 0.19 ug/ml (3.8 ng for a 20 uL injection), and the Limit of Quantification (LOQ) is 0.63 ug/ml (12.7 ng for 20 uL injection). While Scanning Electron Microscope (SEM) shows that the concentrations are relatively low in water samples stored at room temperature compared to those exposed to direct sunlight (40°C) and water bottle samples stored at (-4°C), The correlation coefficients were found to be good (0.9992). SEM is used for plastic bottle samples stored at different temperatures. The images identify compound decay and explore the morphology of BPA in manufactured plastic materials.
基金supported by the National Natural Science Foundation of China (No. 51374215)Fok Ying Tung Education Foundation (No. 142018)+1 种基金Beijing Major Scientific and Technological Achievements into Ground Cultivation Project, the 111 Project (B14006)the National Excellent Doctoral Dissertation of China (No. 201030)
文摘In th is study, th e m eso-failure m ech an ism an d fracture surface o f Jinping m arble w ere investigated bym ean s o f scanning electro n m icroscope (SEM) w ith ben d in g loading system and laser-scanner equipment. The Y antang an d B aishan m arbles specim ens from Jinping II hyd ro p o w er sta tio n w ere used. Testresu lts show th a t th e fracture to u g h n ess and m echanical behaviors o f Y antang m arble w ere basicallyh ig h er th a n th o se o f Baishan m arble. This is m ainly d u e to th e fact th a t Baishan m arble co n tain s a largep ercen tag e o f d o lom ite an d m in o r mica. Crack pro p ag atio n p a th and fracture m orphology in d icated th a tth e d irection o f ten sile stress has a significant effect on th e m echanical behaviors an d fracture toughnesso f B aishan m arble. For Yantang an d B aishan m arbles, a large n u m b e r o f m icrocracks a ro u n d th e m aincrack tip w ere observed w h e n th e directio n o f ten sile stress w as parallel to th e bed d in g plane.C onversely, few m icrocracks o ccurred w h e n th e directio n o f ten sile stress w as p erp en d icu lar to th ebed d in g plane. The presen ce o f a large n u m b e r o f m icrocracks a t th e m ain crack tip d ecreased th e globalfracture to u g h n ess o f m arble. The results o f th re e -p o in t ben d in g te sts show ed th a t th e average bearingcapacity o f intact m arble is 3.4 tim es th e notch ed m arble, b u t th e ductility p ro p e rty o f th e defectivem arble afte r p eak load is b e tte r th a n th a t o f th e intact m arble. H ence, large d efo rm atio n m ay beg en erated before failure o f in tact m arbles a t Jinping II h y d ro p o w er station. The fractal d im en sio n o ffracture surface w as also calculated by th e cube covering m eth o d . O bservational resu lt show ed th a t th elargest fractal dim en sio n o f Y antang m arble is cap tu red w h e n th e directio n o f ten sile stress is parallel toth e bedding plane. H ow ever, th e fractal d im en sio n o f fracture surface o f Yantang an d Baishan m arblesw ith ten sile stress vertical to th e bed d in g plane is relatively sm all. The fractal d im en sio n can also be usedto characterize th e ro ughness o f fracture surface o f rock m aterials.
基金Supported by the National Nature Science Foundation(No.31970217)the One-Hundred Talents Program of Shanxi Provincethe Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0070)。
文摘We detailed the valve morphology of five new species of diatom genus Nupela from wetwall communities in Yunnan Province,China,with light and scanning electron microscope.The five new species demonstrate great variability within the genus,as three of them are biraphid and two are monoraphid.In addition,variation was noted in the structure of internal proximal raphe ends,with some species having anchor-shaped ends and other species have hooked ends.The genus Nupela has grown considerably in 30years since it was first proposed,going from a monotypic genus to over 85 taxa.Diagnosis of the genus is based on the presence of an external covering over the areolae.We discussed the systematic placement of Nupela within the naviculoid diatoms.Yunnan Province appears to harbor many endemic diatom taxa,and many regions of the province have yet to be studied.
基金funded by the State Key Basic Research Program of China(No.2011CB201201)the National Key TechnologyR&D Program(No.2008BAB36B07)the National Natural Science Foundation of China(Nos.51134018 and 50674092)
文摘Non-pillar mining,top-coal caving and protected coal seam mining are the most popular mining methods in coal exploitation,and the different mining layouts will change the stress state and failure mechanism of coal in front of the working face.In this paper,mining-induced mechanical behaviors under three mining layouts have been simulated in the laboratory to investigate the effects of mining layouts on the deformation and strength of coal.Furthermore,the coal failure mechanism under different mining layouts is analyzed microscopically.The experimental results indicate that the stage characteristics of the coal deformation are obvious.Under the serial action of non-pillar mining,top-coal caving and protected coal seam mining layouts,the values of radial deformation,volume strain and Poisson's ratio increase,while the peak strength and deformation modulus decrease at the same buried depth,and the peak strength under non-pillar mining,top-coal caving and protected coal seam mining is about 3.0,2.5 and 2.0 times of the initial confining pressure,respectively.The results also indicate that the trend of the coal deformation decreases with the increase of the buried depth under the same mining layout,while the strength and deformation modulus increase,and the failure mechanism under three mining layouts is dominated with shear/tensile failure.
基金Supported by the projects of Ministry of Science and Technology (No.2001CB409704 and No. 2001BA804A20), and the innovation project ofthe Institute of Oceanology, CAS (No. 200223107)
文摘The morphology and toxicity of Pseudo-nitzschia strain PP0201-01, isolated near the estuary of Changjiang (Yangtze) River in Year 2002 and tentatively identified as Pseudo-nitzschia pungens, were studied. The strain was identified morphologically as P. pungens using scanning electronic microscope (SEM). The ana- lytical results of LC-PDA (liquid chromatography with photodiode array detector), LC-MS (liquid chromatogra- phy with mass detector), and the toxicity data from mouse bioassay, showed that no domoic acid was produced by the strain. However, the mechanism of domoic acid production by Pseudo-nitzschia species is complicated. More works are needed to assess the toxic species and to evaluate the potential risk of amnesic shellfish poison- ing (ASP) in China.
文摘The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray diffractometer (XRD). All the mineral assemblages are similar in these landslides. The main minerals are montmorillonite, illite, kaolinite, chlorite, quartz and feldspar. There are two kinds of surface microtexture in the slipping zone soil, i.e., linear scratches and arcuate scratches. Based on analyses of the changes of the microtextures, one can obtain information about the number, directions and stages of landslide movements. The authors have also studied the mechanism of landslide formation, evaluated the stability of landslides and revival possibility of ancient landslides and forecasted the activity of similar landslides in different districts. The surface microtexture features of stable landslides and mobile landslides are summarized and it is concluded that the existence of filamentous bacteria may result in or increase movements of landslides.
文摘Non Pt based metals and alloys as electrode materials for methyl alcohol fuel cells have been investigated w ith an aim of finding high electrocatalytic surface property for the faster electrode reactions.Electrodes w ere fabricated by electrodeposition on pure Al foil,from an electrolyte of Ni,Co,Fe salts.The optimum condition of electrodeposition w ere found out by a series of experiments,varying the chemistry of the electrolyte,pH valve,temperature,current and cell potential.Polarization study of the coated Ni-Co or Ni-CoFe alloy on pure Al w as found to exhibit high exchange current density,indicating an improved electro catalytic surface w ith faster charge-discharge reactions at anode and cathode and low overvoltage.Electrochemical impedance studies on coated and uncoated surface clearly show ed that the polarization resistance and impedance w ere decreased by Ni-Co or Ni-Co-Fe coating.X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDX)and atomic absorption spectroscopy(AAS)studies confirmed the presence of alloying elements and constituents of the alloy.The morphology of the deposits from scanning electron microscope(SEM)images indicated that the electrode surface w as a three dimensional space w hich increased the effective surface area for the electrode reactions to take place.
基金funding support from the Sichuan Science and Technology Program (Grant No. 2021YJ0511)the State Key Laboratory for Geo-Mechanics and Deep Underground Engineering,China University of Mining&Technology (Grant No.SKLGDUEK2111)the Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province (Grant No. ZJRMG-2020-01)。
文摘Cracked straight-through Brazilian disc(CSTBD) samples prepared using two rock materials were used for thermal treatment from room temperature to 700℃. Uniaxial splitting experiments were performed using an automatic electro-hydraulic servo press to study the evolution laws of physical and fracture properties of different deep rock materials under high-temperature geological conditions. The fracture characteristics were measured using an industrial camera and digital image correlation technology to analyze the effect of high temperature on fracture properties and failure modes of the CSTBD samples after different thermal treatments. The micro-damage properties of green sandstone and granite materials were obtained using a scanning electron microscope(SEM). The following conclusions were drawn from the test results:(1) With the increasing temperature, the fracture characteristics of green sandstone and granite change from brittle fracture to plasticity fracture, the longitudinal wave velocity of granite decreases sharply at 600℃, and the damage factor reaches 0.8748 at 700℃.(2) The fracture toughness of green sandstone and granite decreases with increasing temperature;however, the decreasing range of granite is larger than that of green sandstone.(3) As the temperature increases, the fracture morphologies of green sandstone and granite materials become rougher, whereas thermal damage cracks of granite and intergranular fractures inside sandstone as well as pores of sandstone increase.(4) The crack tip opening displacement and peak strain corresponding to peak load increase with the temperature.
基金funded by the National Natural Science Foundation of China (Grant No.11972018)sponsored by the Defense Pre-Research Joint Foundation of Chinese Ordnance Industry (Grant No. 6141B012858)。
文摘In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40 Cr Mn Si B steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thickness and the number of the circumferential divisions. The results show that as the tempering temperature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.
基金Shanghai Leading Academic Discipline Project,China (No.P1502)
文摘The adherence strength between the metal and the inorganic coating can be greatly increased by mill addition of Li2Ni8O10. The interface structure between metal and the inorganic coating with excellent adherence has been studied by investigating the chemical composition and the microstrncture as well as elements valence bond on the interface with the help of scanning electron microscope (SEM), electron microprobe, and Auger elctron spectroscope (AES). The results show that there is a non-stoichiometrieal transitional layer on the interface between metal and the inorganic coating with excellent adherence, the adherence between metal and the non-stoichiometrical transitional layer is achieved by the metallic bond and the adherence between the non- stoichiometrical transitional layer and the inorganic coating is produced by ionic and covalent bond. The non-stoichiometrical transitional layer results in the strong adherence.
文摘There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and foundations, and tunnel walls, undergo both static and cyclic loading caused by drilling and blasting, and vehicle-induced vibrations. This type of loading often causes rock to fail at a lower than its static strength due to the effect of rock fatigue. A series of laboratory diametrical compression tests was performed on Brisbane tuff disc specimens to investigate their mode-I fracture toughness response to static and cyclic loading, as a function of the applied load. Both the static and cyclic loading tests were carried out on CCNBD (cracked chevron notched Brazilian disc) rock specimens. In the tests described herein, the reduction in fracture toughness under dynamic cyclic loading was found to be up to 48% of the static fracture toughness. Contrary to the static tests, the cyclic tests produced much more crushed material in front of the tip of the chevron notched crack.
基金Funded by the Special Research on Civil Aircraft Quality,Airworthiness and Accident Investigation System (Phase I)-Quality and Reliability Assurance Systemthe National Natural Science Foundation of China (No. 51805500)Technical Foundation Project of Defense Industrial Technology Development Program (No. JSZL2019205C003)。
文摘In order to investigate the influence of natural defect on the fatigue behavior of 5A06/7A05 dissimilar aluminum alloys welding joint,fatigue tests of two types of specimens with and without defects were carried out systematically under stress amplitude control conditions (stress ratio R=0.1) at normal temperature in laboratory air condition.Furthermore,a new parameter,i e,fatigue defect effect factor (FDEF) was introduced to assess the effect of defect on fatigue strength.The fatigue failure analysis was conducted as well to compare the fatigue and fracture behavior of the two types of specimens.The results show that:(1) natural defects have a strong effect on the fatigue lives of welding joint,and the differences between the specimens with and without defects can reach 80 times under a same theoretical net sectional stress;(2) the FDEF parameter introduced is effective to deal with the defect effect,and the FDEF decreases along with the increase of fatigue life.The mean relative error between the experimental data and predicted fatigue strength based on the FDEF is 10.2%;(3) the macro fracture of both types of specimens have three typical zones,i e,fatigue source zone,crack propagation zone and final fracture zone,while there are more than one fatigue sources for specimens with natural defects.The overall pattern of crack propagation zone and fracture zone are quite similar,but the morphologies are different in details.
基金Supported by the National Science&Technology Pillar Program During the 12th Five-Year Plan Period(2014BAC28B01)Beijing Natural Science Foundation(8112012)
文摘Polyhydroxyalkanoates(PHAs)were synthesized in activated sludge using three types of carbon sources(sodium acetate,sodium propionate and sodium butyrate),and their characterization were studied.It was shown that the content of PHA synthesized by microorganisms in activated sludge were different.The biggest synthetic amount up to 36.7% of VSS was obtained when sodium acetate was used as carbon source.The polymer yield was lower when using sodium propionate as the carbon source than when using others,with25.1% of VSS,while resulted in an increase of hydroxyvalerate(HV)units produced.The structure and thermal properties of extracted biopolymers were analyzed by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR)and themogravimetry(TG).
文摘Electrochemical discharge machining is considered to be a hybrid machining process that combines with EDM and ECM (electro chemical machining), called ECDM. The material removal is based on two phenomena: electrochemical dissolution of the material and thermal erosion of electrical discharges that occur between the cathode & anode electrodes. This process is better used for machining of non conducting materials efficiently. In this research paper shows that a brief literature review study of various measuring instruments used for analysis of various parameters of the electrochemical discharge machining process on various types of materials, tool material, input & output parameters such as surface roughness, surface texture, material removal, tool wear etc..
文摘The Historical Wellesley Bridge,built by the Krishnaraja Wadiyar under the supervision of Dewan Purnaih across river Cauvery at Srirangapatna.Situation of bridge is got when heavy rainfall followed by heavy inflow from Cauvery Catchment area in Kodagu District.At present,the Government of Karnataka has taken measures to do the restoration works using the same previously used materials with slight changes.Hence,in the present investigation the authors are doing a case study on the above structure by testing the ingredients of the materials used for it and also by conducting Non-Destructive Test on the structure to know its strength before and after restoration.Based on the test results obtained,the authors will give a conclusion with respect to durability aspects.In addition to the above,the authors will test for few alternative materials i.e.,lime mortar with Cement(i.e.MM2 Grade Masonary mortar).Finally,from the obtained test results here the authors can suggest suitable material for the structures.
文摘The antioxidant of seeds was carried out using extracts from methanol and Silver Nanoparticles from the spice. The SEM shows the shapes, dispersion and agglomeration of the sample, while the EDX confirms the SEM and the presence of some compounds. The FT-IR reveals the AgNP<sub>s</sub> capping and reducing the particular biomolecule from the functional group for identification. Compounds found in the FT-IR seeds of Capsicum annum are Ag L (Silver iodide), C K (Cyanogen chloride), P K (Phenol). Monodora myristica are Mo L (Molybdenum), Ag L (Silver iodide), C K (Cyanogen chloride), P K (Phenol), Mg K (Magnesium). Piper guineense are Ag L (Silver iodide), Ci K (Potassium chloride), C K (Cyanogen chloride), P K (Phenol). The seeds show that the AgNP<sub>S</sub> of CA and MM has a better antioxidant activity than the methanol of CA and MM, while the PG methanol has a better activity than the AgNP<sub>S</sub> PG. The control (Catechin and Galic acid) has a slight overall better DPPH activity than the AgNP<sub>S</sub>. It is important to note that there is a concentration dependency in CA, MM AgNP<sub>S,</sub> PG methanol respectively. Notably, at CA methanol, the conc. at 125 was higher than the conc. at 250. Hence, there is need to create a great part in using plant samples for making tabulated or capsulated drugs for treatment of diseases and using plant silver nanoparticles to develop a healthy food/drug preservative package material “smart packaging” that will enhance shelf-life.
基金supported by the National Key Research and Development Program of China(No.2018YFA0208400)the National Natural Science Foundation of China(NSFC)(Nos.51788104 and 51727805).
文摘Observing the morphology of insulating specimen in scanning electron microscope(SEM)is of great significance for the nanoscale semiconductor devices and biological tissues.However,the charging effect will cause image distortion and abnormal contrast when observing insulating specimen in SEM.A typical solution to this problem is using metal coating or water-removable conductive coating.Unfortunately,in both cases the surface of the specimen is covered by a thin layer of conductive material which hides the real surface morphology and is very difficult to be completely removed after imaging.Here we show a convenient,residue-free,and versatile method to observe real surface morphology of insulating specimen without charging effect in SEM with the help of a nanometer-thick film of super-aligned carbon nanotube(SACNT).This thin layer of SACNT film,like metal,can conduct the surface charge on insulating specimen through the sample stage to the ground,thus eliminating the charging effect.SACNT film can also be used as the conductive tape to carry and immobilize insulating powder or particles during SEM imaging.Different from the metal coating,SACNT film is transparent,so that the real microstructure of the insulating specimen surface can be observed.In addition,SACNT film can be easily attached to and peeled off from the surface of specimen without any residue.This convenient,residue-free,and versatile method can open up new possibilities in nondestructive SEM imaging of a wide variety of insulating materials,semiconductor devices,and biological tissues.
基金This work has been done within the NFFA-EUROPE project and has received funding from the European Union’s Horizon 2020 Research and Innovation Program under grant agreement No.654360 NFFA-EUROPE.
文摘In this paper,we report upon our recent work aimed at improving and adapting machine learning algorithms to automatically classify nanoscience images acquired by the Scanning Electron Microscope(SEM).This is done by coupling supervised and unsupervised learning approaches.We first investigate supervised learning on a ten-category data set of images and compare the performance of the different models in terms of training accuracy.Then,we reduce the dimensionality of the features through autoencoders to perform unsupervised learning on a subset of images in a selected range of scales(from 1μm to 2μm).Finally,we compare different clustering methods to uncover intrinsic structures in the images.
基金supported by the National Basic Research Program of China (Grant Nos.2010CB631005 and 2011CB606105)the National Natural Science Foundation of China (Grant Nos.90916010 and 11172151)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20090002110048)
文摘The fabrication technique of micro/nano-scale speckle patterns with focused ion beam (FIB) system is studied for digital image correlation (DIC) measurement under a scanning electron microscope (SEM).The speckle patterns are fabricated by directly etching the counterpart of the specimen to the black part of a template.Mean intensity gradient is used to evaluate the quality of these SEM images of speckle patterns fabricated based on different templates to select an optimum template.The pattern size depending on the displacement measurement sensitivity is adjusted by altering the magnification of FIB according to the relation curve of the etching size versus magnification.The influencing factors including etching time and ion beam current are discussed.Rigid body translation tests and rotation tests are carried out under SEM to verify the reliability of the fabricated speckle patterns.The calculated values are in good agreement with the imposed ones.