J Shanghai Jiaotong Univ Sci

Select

Ignition-Proof Properties of a High-Strength Mg-Gd-Ag-Zr Alloy

WU Yu-juan1,2 (吴玉娟), PENG Li-ming1,2* (彭立明), ZHAO Su3 (赵素),LI De-jiang1,2* (李德江)

2012 (6): 643-648.
doi: 10.1007/s12204-012-1338-1

摘要 ( 1388 )

A high-strength Mg-15.3Gd-1.8Ag-0.3Zr (GQ152K, mass fraction) alloy was prepared by conventional ingot metallurgy process. The solution and aging (denoted as T6) treated alloy exhibits remarkable mechanical properties with ultimate tensile strength of 421MPa and tensile yield strength of 309MPa. It has higher igniting temperature of 1 208 K. Moreover, it can stand against flame at 1 203K for over 6min in vertical burning tests, and its flammability behavior is very similar to that of 6101Al alloy. Vertical burning tests appear to be able to directly study the flammability behavior of Mg alloys and it appears to be a good approach to study the flammability behavior of Mg alloys in an aircraft fire accident.

参考文献 | 相关文章 | 计量指标

Select

Microstructure and Hardness of Ni-xSi Alloys

LIU Li1,2* (刘礼), MA Xiao-li1 (马晓丽), ZHAO Su3 (赵素)

2012 (6): 648-652.
doi: 10.1007/s12204-012-1339-0

摘要 ( 1514 )

The microstructure and hardness of conventionally solidified Ni-xSi (x = 21.4%, 22%, 24%, 26%) alloys were investigated. The solidification microstructures of different Ni-Si alloys were observed by optical microscope (OM) and scanning electron microscope (SEM) and the phase composition was indentified under the help of energy dispersive X-ray (EDX) analysis. The macro- and micro-hardness of the Ni-Si alloys at room temperature were also examined. The experimental results indicated that both the microstructure and hardness closely depended on the Si content. Due to the vast formation of primary γ-Ni31Si12 phase, the hardness of Ni-26.0%Si alloy was significantly improved compared with that of Ni-21.4%Si eutectic alloy. However, the fracture toughness was greatly weakened simultaneously. The (β1-Ni3Si+γ-Ni31Si12) lamellar eutectoid structure formed in the primary γ-Ni31Si12 phase exhibited better ductility than single γ-Ni31Si12 phase at the cost of relatively small hardness reduction.

参考文献 | 相关文章 | 计量指标

Select

Effects of Cooling Rates on Microstructures and Mechanical Properties of Nb-Ti Microalloyed Steel

ZHAO Su1* (赵素), WU Yu-juan2* (吴玉娟), HE Mei-feng3 (何美凤), ZHANG Li4 (张立)

2012 (6): 653-657.
doi: 10.1007/s12204-012-1340-7

摘要 ( 1662 )

The mechanical properties and microstructure of as-cast Nb-Ti microalloyed steel at different temperatures and cooling rates are investigated in this paper. The III brittle zone (700—900℃) is revealed. The reduction of the hot ductility is due to the film-like proeutectoid ferrite or the Nb(C, N) precipitates along the austenitic grain boundaries. In the temperature range of 850—1 000℃, with the increase of the cooling rate, the hot ductility decreases. However, in the range of 650—850℃, the appearance of large volume fractions of ferrite on austenite grain boundaries minimizes the effect of cooling rate on hot ductility. When the cooling rate is 10℃/s, austenite transforms more quickly to ferrite and at a lower temperature a larger amount of ferrite nucleates and precipitates in the grain, which leads to a sharper improvement in the hot ductility at 650℃.

参考文献 | 相关文章 | 计量指标

Select

Effect of Gr Content and Hot Extrusion on Tensile Properties of (Nano-SiCp+Gr)/Cu Composites Fabricated by Powder Metallurgy

WANG Gui-songa,b* (王桂松), LUO Yanga (罗阳), LIU Bao-xia (刘宝玺),YIN Chenga (尹成), GENG

2012 (6): 658-662.
doi: 10.1007/s12204-012-1341-6

摘要 ( 1828 )

Novel hybrid Cu matrix composites reinforced by graphite (Gr) particle with volume fraction of 5%— 15% and nano-SiC particle (nano-SiCp) with volume fraction of 3% have been prepared by powder metallurgy. The results show that Gr and nano-SiCp distribute uniformly in the Cu matrix. With increasing the volume fraction of Gr, the tensile strength of the composites decreases from 114 to 51MPa and the elastic modulus decreases from 75 to 60GPa. Compared with the sintered composites, the tensile properties including elastic modulus, tensile strength, yield strength and tensile elongation of the hot-extruded (nano-SiCp+Gr)/Cu composites are improved greatly due to higher relative density of the composites and more uniform distribution of Gr and nano-SiCp, in addition to finer grain size of the matrix as a result of dynamic recovery and recrystallization which occur during hot extrusion process.

参考文献 | 相关文章 | 计量指标

Select

Microstructure of Hot-Dip Galvanized Zn-Al-Mg Alloy Coating

YU Kang-cai1,2 (余康才), LI Jun2* (李俊), LIU Xin2 (刘昕), LI Jian-guo1 (李建国), XUE Xiao

2012 (6): 663-667.
doi: 10.1007/s12204-012-1342-5

摘要 ( 2076 )

The microstructure of hot-dip galvanized Zn-11%Al-3%Mg-0.2%Si alloy coating was studied in this article. X-ray diffraction analysis revealed the coating is composed by Zn, Al andMgZn2 phase. Optical microscope (OM) and scanning electron microscope (SEM) observations showed the coating is occupied by snowflake-like dendrite, double hexagonal organization and eutectic. The coating backbone was the dendrite considered to be a phase of hexagonal close-packed (HCP) structure judging form its morphology according to the crystal growth way in the coating. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) researches on the dendrite suggested that an intermediate Zn-Al phase was formed at high temperature, then decomposed into a type of Zn-Al granular eutectoid after cooling down to room temperature, while the eutectoid Zn and Al had a certain crystallographic relationship. The coating solidification process and the grain crystal structure were discussed.

参考文献 | 相关文章 | 计量指标

Select

Effects of Micro-arc Oxidation Coating on Corrosion Behavior of Mg-Y-Zn in Simulated Body Fluid

LU Tian-feng (卢天凤), YIN Kai-yang (尹恺阳), SUN Bing-yi (孙秉毅),DONG Qing (董晴), CHEN B

2012 (6): 668-672.
doi: 10.1007/s12204-012-1343-4

摘要 ( 2011 )

The application of magnesium and its alloy as degradable biomaterials is mainly confined due to its high degradation rate in physiological environment. This research focused on the effects of micro-arc oxidation (MAO) on biodegradable behavior of Mg-Y-Zn magnesium alloy in a simulated body fluid (SBF). The corrosion rate of alloys was gauged by means of hydrogen evolution volume measurement and mass-loss method. Scanning electron microscope (SEM) was utilized to observe the surface of the magnesium alloy and the cross-section of oxidation coating layer before and after corrosion. The Mg-Y-Zn alloy with thicker oxidation coating exhibited greater corrosion resistance during the immersion test for 240 h.

参考文献 | 相关文章 | 计量指标

Select

Self-Organizing Map Based Quality Assessment for Resistance Spot Welding with Featured Electrode Displacement Signals

WANG Shuan-yuan (王双园), GONG Liang* (贡亮), LIU Cheng-liang (刘成良)

2012 (6): 673-678.
doi: 10.1007/s12204-012-1344-3

摘要 ( 1510 )

To classify the quality of the resistance spot welding process, a relationship between the welder electrode displacement curve characteristics and the weld shear force has been explored. Eleven statistical features of the displacement signals are extracted to represent the welding quality. Self-organizing map (SOM) neural networks have been employed to discover their quantitative relationship. In order to identify the influence of various displacement curve features, all of the available combinations have been used as inputs for SOM neural networks. Further we analyze the impact of each feature on the classification results, yielding the best quality-indicative combination of characteristics. There is no determinant relationship between the welding quality and the level of expulsion rate. The quality of welding is most impacted by the maximum electrode displacement, the span of welding process and the centroid of the electrode displacement curve. The experiments show that SOM is feasible to assess the welding quality and can render the visualized intuitive evaluation results.

参考文献 | 相关文章 | 计量指标

Select

Microstructure and Property of Friction Stir Welding Joint of 7075Al and AZ31BMg

LI Da1,2 (李达), CUI Zhan-quan2 (崔占全), YANG Qing-xiang2* (杨庆祥),SUN Bing1 (孙兵), SUN

2012 (6): 679-683.
doi: 10.1007/s12204-012-1345-2

摘要 ( 2014 )

Microstructure and forming quality of friction stir welding joints of 7075Al and AZ31BMg with different welding parameters were analyzed. The results show that, good welded joint is obtained when the rotating frequency is 13 r/s and the welding speed is 30 mm/min. An irregular area is formed in the welding center. Meanwhile, the river pattern and eddy-like distribution are found in the weld nugget zone. Besides, brittle intermetallic compounds Al12Mg17 and Al3Mg2 are found in the welded joint. They cause the increase of microhardness of welded joint. The maximum tension stress of welded joint is 112MPa.

参考文献 | 相关文章 | 计量指标

Select

Friction Characteristics in Green Drilling Titanium Alloy Ti6Al4V

WU Jian1* (吴健), HAN Rong-di2 (韩荣第)

2012 (6): 684-689.
doi: 10.1007/s12204-012-1346-1

摘要 ( 1309 )

Titanium alloy Ti6Al4V, as difficult-to-cut material, has poor machinability. Conventional cutting fluid serves as a coolant and lubricant. In green drilling, water vapor is recognized as an effective coolant; however, its lubrication properties are not well known in drilling. This paper investigates the friction characteristics between chip and tool in green drilling Ti6Al4V, compared with that in sliding and turning process. A friction evaluation model is developed based on the equivalent model of drilling, then is used to calculate the effective friction coefficient. Results indicate that the friction coefficient on the tool-chip interface is considerably reduced in drilling by water vapor, so the drilling forces decrease, too. The friction coefficient decreases as velocity increases in drilling, which is different from the law of sliding tests; the friction coefficient increases when the distance to chisel edge increases.

参考文献 | 相关文章 | 计量指标

Select

Research on Online Texture Measurements in Metal Rolling Field

HE Fei* (何飞), YIN An-min (殷安民), YANG Quan (杨荃)

2012 (6): 690-696.
doi: 10.1007/s12204-012-1347-0

摘要 ( 1563 )

In rolled strip material, the orientation of the crystallites, known as texture, is influenced by various kinds of thermo-mechanical processes, such as casting, plastic deformation, annealing and phase transformation. The modern industry production requires stable product performance, real-time monitoring and full controlling of the quality. The online texture measurement in metal rolling can be used to real-time monitor the whole process, and then feedback control to the production process can be implied to adjust the process parameters to ensure the stability of the products. The principles, advantages and disadvantages of related detection methods (2D Xray diffraction, neutron diffraction, laser-ultrasonics and electromagnetic acoustic transducers (EMAT)) and the possibility of online measurement are discussed. Finally, 2D X-ray diffraction and laser-ultrasonics are employed on online texture measurement, and the schemes of online texture measurement are proposed.

参考文献 | 相关文章 | 计量指标

Select

Improvement the Electrochemical Performance of Li1.2Ni0.2Mn0.6O2 Electrode with AlF3 Added

LIU Yun-jian1,2,3* (刘云建), LIU San-bing2 (刘三兵), CHEN Xiao-hua2 (陈效华), CHEN Long3

2012 (6): 697-700.
doi: 10.1007/s12204-012-1348-z

摘要 ( 1484 )

Layered solid solution material Li1.2Ni0.2Mn0.6O2 is synthesized and the AlF3 is added to improve the electrochemical performance. X-ray diffraction (XRD) results show that the Li1.2Ni0.2Mn0.6O2 samples exhibit layered characteristics. The AlF3 additive is detected by transmission electron microscope (TEM) technology. The electrochemical tests show that Li1.2Ni0.2Mn0.6O2 electrode with AlF3 added delivers better discharge capacity (240mA· h/g), first coulomb efficiency 79.2%, cyclic performance (capacity retention ratio of 100.6% after 50 cycles), and rate capacity (68mA· h/g at 10 capacity (C)) than the pristine sample. Electrochemical impedance spectroscopy (EIS) results show that the charge transfer resistance of Li1.2Ni0.2Mn0.6O2 electrode with AlF3 added increases slower than that of pristine Li1.2Ni0.2Mn0.6O2 after cycling, which is responsible for better cyclic and rate performance.

参考文献 | 相关文章 | 计量指标

Select

Fabrication of a Novel Porous Poly(Vinylidene Fluoride) Blend Five-Bore Membrane for Wastewater Treatment

HUANG Jian-ping1,2,3 (黄健平), MA Chun-yan2 (马春燕), XI Dan-li2 (奚旦立), YAN Ke-lu1* (阎

2012 (6): 701-705.
doi: 10.1007/s12204-012-1349-y

摘要 ( 1361 )

Porous poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend five-bore hollow fiber membranes are prepared by wet phase inversion methods. In spinning these PVDF hollow fibers, N, N-dimethylacetamide (DMAc) and polyvinyl pyrrolidone (PVP) are used as the solvent and the non-solvent additive, respectively. The external coagulant uses water. The internal coagulants use water and DMAc-water solutions. The membranes are characterized in terms of water flux and molecular weight cut-off for the wet membranes. The cross-sectional structures are examined by scanning electron microscopy (SEM). The effects of polymer concentration and the internal coagulant on the permeation properties and membrane structures are examined keeping the bore liquid flow and air-gap constants. Relative high flux, rejection and strengh PVDF five-bore hollow fiber membranes could be prepared from the polymer concentration in dope solution at 17% of mass fraction, the air gap distance of 14 cm, and using 10% of mass fraction of DMAc solution as the internal coagulant at 13mL/min of flow.

参考文献 | 相关文章 | 计量指标

Select

Mechanical Properties and Residue Stress of Four Kinds of ZrC Coatings Prepared by Chemical Vapor Deposition

SUN Weia* (孙威), XIONG Xianga (熊翔), LI Xiao-binb (李小斌), LI Guo-donga (李国栋)

2012 (6): 706-711.
doi: 10.1007/s12204-012-1350-5

摘要 ( 1382 )

Four kinds of ZrC coatings with nearly the same thickness have been successfully prepared on graphite substrate by chemical vapor deposition (CVD) through controlling the ratio of inlet reacting gases. From backscattered electron images, it can be inferred that ZrCIII coating has the best tightness of all coatings. Meanwhile, line energy spectrum curve shows that zirconium and carbon elements distribute uniformly along the normal direction of the ZrCIII coating. As for varied microstructures, the coatings show different mechanical properties and residue stress. The strength and elastic modulus of ZrCIII coating were up to 89.57 and 1 192.5GPa, respectively. Those make it near the level of diamond. Value of residue tensile stress of ZrC+C composite coating was only 7.729MPa and that of ZrCIII coatings was 349.632 MPa. The strong combination of small-size grains in ZrCIII coating plays a decisive role to the best mechanical properties. However, strong misfit of lattice between ZrCIII coating and substrate can induce high residue stress.

参考文献 | 相关文章 | 计量指标

Select

Preparation and Characterization of a Novel Hybrid Copolymer Hydrogel with Poly(ethylene glycol) Dimethacrylate, 2-Hydroxyethyl Methacrylate and Layered Double Hydroxides

WANG Pei1* (王沛), WEI Zhi-yong2 (魏志勇), CHENG Jiang1 (程江), LIU Lian1 (刘炼)

2012 (6): 712-716.
doi: 10.1007/s12204-012-1351-4

摘要 ( 1487 )

This paper describes the fabrication, characterization and properties of a novel hybrid poly(ethylene glycol) (PEG) based hydrogel via in situ polymerization. The hybrid hydrogel was fabricated by free-radical redox polymerization using ammonium persulfate (APS) and N, N, N, N-tetramethylethylenediamine (TEMED) as initiators and N, N-methylene bisacrylamide (BIS) as cross-linker at 60℃. To create a hybrid hydrogel, 0.2% (mass fraction) of MgAl layered double hydroxide (LDH) was added to the aqueous solution by ultrasonic dispersion. The physicochemical properties of hybrid hydrogel under vacuum freeze-drying processing were characterized by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM), while swelling kinetics and gel content were calculated. Swelling degree in distilled water varied from 94%—125% with a gel mass fraction of 83%—91%. SEM images showed that the micron pore size of hydrogel could be adjusted within the range of several micrometers by changing the cross-linker mass fraction from 2% to 10% (based on glycol). The results showed that the hybrid hydrogels exhibited excellent physicochemical behavior and might be a promising material for applications in tissue engineering and drug delivery.

参考文献 | 相关文章 | 计量指标

Select

Biocompatibility Evaluation of Polyethylene Terephthalate Artificial Ligament Coating Hydroxyapatite by Fibroblasts Cells in Vitro

JIANG Jia1 (蒋佳), HAO Wei2 (郝威), LI Yu-zhuo1 (李毓卓), CHEN Jun3* (陈俊),YAO Jin-rong3

2012 (6): 717-722.
doi: 10.1007/s12204-012-1352-3

摘要 ( 1441 )

Hydroxyapatite (HA) based materials have been widely used in the field of ligament tissue engineering in the past decades. It has been previously reported that HA can increase the penetration of marrow-derived mesenchymal stem cells (MSCs) and MSCs cells into scaffolds due to increased cell differentiation in biological media. Additionallyit was found that there are much difference between MSCs and anterior cruciate ligament (ACL) cells. For that reason, we mainly evaluate the biocompatibility of polyethylene terephthalate (PET) silk scaffold with fibroblasts cells in vitro. We cultured mouse fibroblasts cells on the substrate of PET fiber and PET-HA scaffold, respectively, and then observed the morphology by using scanning electron microscopy. Our data indicate that PET-HA scaffold has good biocompatibility with fibroblasts cells and can potentially be useful in enhancing the fibroblasts cell differentiation and proliferation.

参考文献 | 相关文章 | 计量指标

Select

Effect of Oil Shale on Na+ Solidification of Red Mud-Fly Ash Cementitious Material

LIU Xiao-ming1,2* (刘晓明), LI Yu1,2 (李宇), SUN Heng-hu3 (孙恒虎), CANG Da-qiang1,2 (苍大

2012 (6): 723-729.
doi: 10.1007/s12204-012-1353-2

摘要 ( 1295 )

Red mud-fly ash based cementitious material mixed with different contents of oil shale calcined at 700 ℃ is investigated in this paper. The effect of active Si and Al content on the solidification of Na+ during the hydration process is determined by using X-ray diffraction (XRD), 27Al and 29Si magic-angle-spinning nuclear magnetic resonance (MAS-NMR), infrared (IR), scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the content of oil shale has a remarkable effect on the solidified content of Na+. The hydration process generates a highly reactive intermediate gel phase formed by co-polymerisation of individual alumina and silicate species. This kind of gel is primarily considered as 3D framework of SiO4 and AlO4 tetrahedra interlinked by the shared oxygen atoms randomly. The negative charges and four-coordinated Al inside the network are mainly charge-balanced by Na+. The solidifying mechanism of Na+ is greatly attributed to the forming of this kind of gel.

参考文献 | 相关文章 | 计量指标

Select

Photothermal Effect for Fe3O4 Nanoparticles Contained in Micelles Induced by Near-Infrared Light

LIU Guang-zhen1,2* (刘光臻), MA Jun-ping1,2 (马俊平), LIU Jia-qiang3 (刘家强)

2012 (6): 730-733.
doi: 10.1007/s12204-012-1354-1

摘要 ( 1767 )

Near infrared (NIR) light induced photothermal effect for Fe3O4 nanoparticles, contained in Pluronic F127 micelles, has been studied and it exhibits high photothermal converting efficiency. Heat is found to be rapidly generated in micelles containing Fe3O4 nanoparticles by NIR laser irradiation. Upon irradiation at 808 nm light and with mass concentration of Fe3O4 nanoparticles in 4 g/L, the micelle temperature increase is higher than 34℃ for 10min irradiation. The maximum temperature of micelles containing Fe3O4 nanoparticles in 4 g/L reaches 62℃.

参考文献 | 相关文章 | 计量指标

Select

Microwave Hydrothermal Synthesis and Characterization of ZnO Nanostructures in Aqueous Solution

GUO Li-tong1* (郭立童), WU Jing1 (武静), GUO Li-zhi2 (郭立芝),ZHU Ya-bo1 (朱亚波), XU Cheng

2012 (6): 734-737.
doi: 10.1007/s12204-012-1355-0

摘要 ( 1602 )

ZnO nanostructures were prepared in aqueous solution by microwave hydrothermal synthesis. Xray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize ZnO nanostructures (ZNs). The effects of pH, reaction temperature and reaction time on yield of ZnO were investigated. The yield of ZnO increased significantly with the increase of pH value, reaction temperature and reaction time. High yield and well crystallinity of ZNs could be obtained at 120℃ for 60min by microwave hydrothermal synthesis. The spherical and rugby-like ZNs were obtained at 120℃ without triethanolamine (TEA) and with TEA (mass ratio, r = mZn2+ : mTEA = 1 : 1), respectively. The concentration of Zn(OH)2 4 ions in the reaction solution and TEA had an important effect on the nucleation and morphology of ZnO nanostructures. Mechanism for the formation of ZnO nanostructures was proposed.

参考文献 | 相关文章 | 计量指标

Select

Effect of Cu Co-doping on the Magnetism of Zn0.95Co0.05O Films

LI Jian-jun1,2 (李建军), ZHU Jin-bo1* (朱金波), ZHANG Li-ting1 (张丽亭),LIU Yin1 (刘银), HA

2012 (6): 738-742.
doi: 10.1007/s12204-012-1356-z

摘要 ( 1461 )

Zn0.95-xCo0.05CuxO (atomic ratio, x = 0—8%) thin films are fabricated on Si(111) substrate by reactive magnetron sputtering method. Detailed characterizations indicate that the doped Cu ions substitute the Zn2+ ions in ZnO lattice. The doped Cu ions are in +1 and +2 mixture valent state. The ferromagnetism of the Zn0.95-xCo0.05CuxO film increases gradually with the increase of the Cu+ ion concentration till x = 6%, but decreases for higher Cu concentration. Experimental results indicate that the increase of ferromagnetism is not owing to the magnetic contribution of Cu+ ions themselves, but owing to the enhancement of magnetic interaction between Co2+ ions, which suggests that p-type doping of Cu+ ions plays an important role in mediating the ferromagnetic coupling between Co ions.

参考文献 | 相关文章 | 计量指标

Select

Composition-Dependent Mechanical and Thermal Transport Properties of Carbon/Silicon Core/Shell Nanowires

JING Yu-hanga,b* (荆宇航), YU Kai-pinga (于开平), QIN Xiana (覃弦), SHEN Junb* (沈军)

2012 (6): 743-747.
doi: 10.1007/s12204-012-1357-y

摘要 ( 1975 )

Abstract: Molecular dynamics (MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires (NWs). For each concerned carbon/silicon core/shell NW with a specified diameter, it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio. The fact matches well with the results of theoretical model. Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support. On the other hand, thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell. The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases. In addition, by calculating the phonon density of state, we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes. These results provide an effective way to modify the properties of core/shell NWs for related application.

参考文献 | 相关文章 | 计量指标

Select

Temperature Dependence of Microwave Dielectric Performance of Silica

ZHANG Ting1,2*(张婷), WU Meng-qiang2 (吴孟强), ZHANG Shu-ren2 (张树人), HE Ming2 (何茗),LI

2012 (6): 748-754.
doi: 10.1007/s12204-012-1358-x

摘要 ( 1556 )

The dielectric properties of silica at temperature from 300 to 1 600K and at microwave frequency band are investigated. By use of material studio software, the lattice constant, band energy gap and optical permittivity of silica are calculated, and to be used as the key parameters to investigate the microwave dielectric properties of silica. It is found that its permittivity and loss are increased with increasing temperature. In addition, the ionic conduction loss caused by the defects in silica is very small from the calculation and the value is about 10^5 level at 2 000 K. The application of this analysis allows to estimate the permittivity and dielectric loss of silica both at high temperature and microwave band, which is currently still difficult to be measured directly.

参考文献 | 相关文章 | 计量指标

Select

Recognition of Red Cell and Megakaryocyte Based L-Shaped Envelope Function

YU Ye-hua1 (俞夜花), ZHENG Xi-tao2 (郑西涛), ZHANG Yong-wei2 (张永伟),YANG Kun2 (杨堃), ZH

2012 (6): 755-760.
doi: 10.1007/s12204-012-1359-9

摘要 ( 1334 )

In order to explore the cell composition and its metabolism, it is important to let computer recognize the cells and get the counts of different cells for a sample. This paper proposes an L-shaped envelop function and the related fuzzy clustering method as a way to identify the megakaryocyte and the red cell from the sliced marrow image. This method is useful when the staining is insufficient and the color cannot be used as the identifying factor. This method uses the experimental histogram data to fit the L-shaped function and then use it as the envelop for the match test. The fuzzy c-means (FCM) performance index is used to test the adjacent area and get the minimum and finally secure the identification. The new method is not limited to megakaryocyte or red cell and can be used for general purposes of cell recognition. Tests show that this envelop function can ensure the recognition rate with different staining batches and can reach satisfied counting under similar illumination condition.

参考文献 | 相关文章 | 计量指标

Select

Survey on Arteriovenous Fistula in Maintenance Hemodialysis Patients with Type 2 Diabetic Nephropathy

WANG Feng1 (王锋), ZHOU Yang2 (周阳), LI Jun-hui1 (李军辉), GUI Ding-kun1 (桂定坤),LU Sh

2012 (6): 761-764.
doi: 10.1007/s12204-012-1360-3

摘要 ( 1229 )

This paper summed up the characteristics of native arteriovenous fistulas (AVFs) in maintenance hemodialysis patients with type 2 diabetic nephropathy (DN) in Chinese hemodialysis centers. A survey was conducted on AVF in maintenance hemodialysis patients with type 2 DN. A total of 224 cases of maintenance hemodialysis patients were included in this study, among which, 65 cases in DN group, 33 cases in diabetes mellitus (DM) group and 126 cases in non-diabetic control (C) group. Hemoglobin, albumin, blood urea nitrogen, parathyroid hormone and calcium-phosphate product of the three groups of patients were not significantly different. Glycated hemoglobin A1c of DN group and DM group was not significant different. AVF life of (28.7 ± 10.0) months in DN group was significantly shorter than that of (36.5 ± 19.4) months in C group (statistic probability P <0.01), and AVF life of (32.5 ± 10.1) months in DM group (P <0.05) was also shorter than that in C group, while there was no significant difference in AVF life between DN group and DM group. Proportion of upper arm fistula in DN patients (11/65) was significantly higher than that in C group (6/123, P < 0.01). Life of AVF in patients with DN was relatively short, with more times of angioplasty and greater possibility of selecting upper arm internal fistula.

参考文献 | 相关文章 | 计量指标

期刊目录