H-600型电子显微镜镜体的清洗

文章详细介绍了H-600型电子显微镜镜体清洗时的解体步骤,对不同的部件和材质采取不同的处理手段以及在真空状态下检查各主要部件被污染情况的简便方法。

1000B型扫描电子显微镜合轴的调整

本文介绍了扫描电子显微镜(下称"电镜")的基本原理,分析了扫描电镜的常见故障和具体原因,重点阐述了1000B电镜因为合轴不良导致的故障类型以及调整原理,并以此为基础,为改善1000B电镜的成像质量,提出了调整电镜合轴的具体技术和操作方法。

溶菌酶协同高压CO_2对酸土脂环酸杆菌芽孢的致死效果

以芽孢致死率为评价指标,通过单因素和正交试验考察溶菌酶添加量、压力、温度和时间在高压CO2处理过程中对酸土脂环酸杆菌芽孢致死效果的影响,并优化杀菌条件。结果显示:溶菌酶添加量、压力和温度对芽孢致死效果的影响均显著(P<0.05),在溶菌酶添加量0.10g/kg、压力25MPa、温度55℃、时间60min的优化条件下芽孢致死率可达到5.47个数量级。另对此条件下处理后的样品进行高效液相色谱(HPLC)和扫描电子显微镜(SEM)检测,结果显示:芽孢核心物质2,6-吡啶二羧酸(DPA)发生大量泄露,且部分芽孢完全破裂,溶菌酶对高压CO2杀灭芽孢的协同效果显著(P<0.05)。

Development of advanced electron tomography in materials science based on TEM and STEM

The recent developments of electron tomography（ET） based on transmission electron microscopy（TEM） and scanning transmission electron microscopy（STEM） in the field of materials science were introduced. The various types of ET based on TEM as well as STEM were described in detail, which included bright-field（BF）-TEM tomography, dark-field（DF）-TEM tomography, weak-beam dark-field（WBDF）-TEM tomography, annular dark-field（ADF）-TEM tomography, energy-filtered transmission electron microscopy（EFTEM） tomography, high-angle annular dark-field（HAADF）-STEM tomography, ADF-STEM tomography, incoherent bright field（IBF）-STEM tomography, electron energy loss spectroscopy（EELS）-STEM tomography and X-ray energy dispersive spectrometry（XEDS）-STEM tomography, and so on. The optimized tilt series such as dual-axis tilt tomography, on-axis tilt tomography, conical tilt tomography and equally-sloped tomography（EST） were reported. The advanced reconstruction algorithms, such as discrete algebraic reconstruction technique（DART）, compressed sensing（CS） algorithm and EST were overviewed. At last, the development tendency of ET in materials science was presented.

Colonization Pattern of Azospirillum brasilense Yu62 on Maize Roots

Plasmid pVK1001 which carried the gfp gene of GFPmut2, a mutant of GFP, was introduced into Azospirillum brasilense Yu62 by electroporation. Maize seedlings were inoculated with the GFP-labelled baeteria and grown gnotobiotically in flask with semi-solid agar medium. Observations were performed with confocal laser scanning microscopy (CLSM) and electron microscopy, respectively, at 8 d and 12 d after inoculation. Confocal laser scanning microscopy showed that A. brasilense Yu62 could penetrate into the cortex tissue, colonizing in the intercellular spaces of the parenchyma cells of the cortex tissue. Transmission and scanning electron microscopy (TEM) showed that the majority of the bacteria colonized on the root surface and only a minority of them resided in the root interior.

On Cuticular Compressions of Glyptostrobus europaeus (Taxodiaceae) from Kaydagul Formation (Lower Miocene) of the Central Kazakhstan$V. L. Komarov Botanical Institute! Russian Academy of Sciences,St Petersburg 19737

Numerous leaf compressions of Glyptostrobus europaeus (Brongn.) Ung. (Taxodiaceae) are found in Aquitanian (Lower Miocene) lignified clay localities Bolattam and Akzhar in the Southern Turgay, on the right bank of the Dulygaly-Zhilanshik river (Central Kazakhstan). The finely preserved lignified compression remains of leafy shoots make micro-morphological investigation feasible. Comparative studies of the epidermal features both living G. pensilis C. Koch and a new finding of G. europaeus from Early Miocene of Kazakhstan and illustrate their certain difference. The cuticular organization and epidermal features of fossil leaves, which have been compared with these of 'the nearest living relative', G. pensilis, were studied by scanning electron microscopy (SEM) and light microscopy (LM). The fossil leaves of G. europaeus from Kazakhstan are distinguished by stronger, than in living species, G. pensilis, developed 'micro-papillae' ('Kristallucken'), visible in SEM as ring-like structures left on the outer surface of cuticle in both nonstomatal and stomatal zones.

Studies on the Tolerating Mechanism for Sulfide in Urechis unicinctus (Echiura: Urechidae) ──Cytological Observation on Urechis unicinctus in Different Hydrogen Sulfide Environment

This study on the cytological changes of the body wall,aspiratory intestine and crissal bursa in Urechis unicinctus by light microscope (LM) and transmission electron microscope (TEM) showed that the difference between the body wall and the natural environment rich in H 2S was not obvious; that the wall color of the aspiratory intestine in H 2S rich environment changed from normal semitransparency to dark brown; that its epithelia were disassembled and the electron density of its cytoplasm matrix was lower; and that in H 2S rich environment many basophilic granules occurred in the epithelia of the crissal bursa. Granules with single membrane and myelinefingure were found with TEM.

Effect of low temperature thermo-mechanical treatment on microstructures and mechanical properties of TC4 alloy

The effects of low temperature thermo-mechanical treatment （LTTMT） on microstructures and mechanical properties of Ti-6Al-4V （TC4） alloy were studied by optical microscopy （OM）, tensile test, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The experimental results confirm that the strength of TC4 alloy can be improved obviously by LTTMT processing, which combines strain strengthening with aging strengthening. The effect of LTTMT on the alloy depends on the microstructure of the refined and dispersed a＋fl phase on the basis of high dislocation density by pre-deformation below recrystallization temperature. The tensile strength decreases with the increase of pre-deformation reduction. The optimal processing parameters of LTTMT for TC4 alloy are as follows： solution treatment at 900 ℃ for 15 min, pre-deformation in the range of 600-700 ℃ with a reduction of 35%, finally aging at 540 ℃ for 4 h followed by air-cooling.

Effects of Yb addition on microstructures and mechanical properties of 2519A aluminum alloy plate

The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test,optical microscopy,transmission electron microscopy,scanning electron microscopy and X-ray diffractometer.The results show that addition of 0.17% (mass fraction) Yb increases the density of θ' particles of the 2519A alloy plate and reduces the coarsening speed rate of θ' phase at 300 ℃.Therefore,tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 ℃.The results also show that with the addition of 0.30% (mass fraction) Yb,the mechanical properties increase at 300 ℃ and decrease at room temperature.With Yb additions,the Al7.4Cu9.6Yb2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous,thin and spheroidized.

Influence of cerium on microstructures and mechanical properties of Al-Zn-Mg-Cu alloys

Effect of element cerium （Ce） on microstructure and mechanical properties of A1-Zn-Mg-Cu alloys has been investigated by transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, differential scanning calorimetry （DSC） and hardness test. The results show that addition of Ce can remarkably refine the as-cast grains and eutectic microstructure. A transformation from Mg（Zn,Cu,A1）2 phase to A12CuMg phase is observed during homogenization. Furthermore, the Ce addition introduces changes in the precipitation process and consequently in the age-hardening behavior of the alloy. Microstructural measurements reveal that the addition of Ce promotes the precipitation of η＇ phase, but it also partly retards the precipitation of GP zones. The density of precipitates decreases in a certain degree and rod-like η＇ precipitates increase when Ce content is from 0.2% to 0.4% （mass fraction）.

Supercritical Antisolvent-based Technology for Preparation of Vitamin D3 Proliposome and Its Characteristics

Vitamin D3 （VD3） proliposomes （VDP）, consisted of hydrogenated phosphatidycholine （HPC） and VD3, were prepared using supercritical anti-solvent technology （SAS）. The effects of operation conditions （temperature, pressure and components） on the VD3 loading in VDP were studied. At the optimum conditions of pressure of 8.0 MPa, temperature of 45 ℃, and the mass ratio of 15.0% between VD3 and HPC, the VD3 loading reached 12.89%. VD3 liposomes （VDL） were obtained by hydrating VDP and the entrapment efficiency of VD3 in VDL reached 98.5%. The morphology and structure of VDP and VDL were characterized by SEM （scanning electron micro-scope）, TEM （transmission electron microscope） and XRD （X-ray diffractometer）. The structure of VD3 nanoparti-cles in HPC matrix was formed. The size of VDL with an average diameter of about 1μm was determined by dynamic light scattering instrument （DLS）. The results indicated that VDP can be made by SAS and VDL with high entrapment efficiency can be formed easily via the hydration of VDP.

Nanocrystalline Mg and Mg alloy powders by hydriding-dehydriding processing

The process of mechanically assisted hydriding and subsequent thermal dehydriding was proposed to produce nanocrystalline Mg and Mg alloy powders using pure Mg and Mg-5.5%Zn-0.6%Zr(mass fraction)(ZK60 Mg) alloy as the starting materal.The hydriding was achieved by room-temperature reaction milling in hydrogen.The dehydriding was carried out by vacuum annealing of the as-milled powders.The microstructure and morphology of both the as-milled and subsequently dehydrided powders were characterized by X-ray diffraction analysis(XRD) ,transmission electron microscopy(TEM) ,and scanning electron microscopy(SEM) ,respectively.The results show that,by reaction milling in hydrogen,both Mg and ZK60 Mg alloy can be fully hydrided to form nanocrystalline MgH2 with an average grain size of 10 nm.After subsequent thermal dehydriding at 300℃,the MgH2 can be turned into Mg again,and the newly formed Mg grains are nanocrystallines,with an average grain size of 25 nm.

A yttrium-containing high-temperature titanium alloy additively manufactured by selective electron beam melting

A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and textures were studied using scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and electron backscattered diffraction(EBSD) and compared with the conventionally manufactured form. A notable distinct difference of microstructures is that additive manufacturing by SEBM enables homogeneous precipitation of fine Y2O3 dispersoids in the size range of 50-250 nm throughout the as-fabricated alloy, despite the presence of just trace levels of oxygen(7×10-4, mass fraction) and yttrium(10-3, mass fraction) in the alloy. In contrast, the conventionally manufactured alloy shows inhomogeneously distributed coarse Y2O3 precipitates, including cracked or debonded Y2O3 particles.

Existing form and action mechanism of minor scandium and zirconium in Al-Cu-Mg alloy

In order to investigate the existing form and action mechanism of minor scandium （Sc） and zirconium （Zr） in AI-Cu-Mg alloy, microstructures of Al-4Cu-1Mg-Sc-Zr alloy under different conditions, including states of as-cast, homogenized, hot-rolled, as-solution and natural aged, were observed by scanning electron microscopy （SEM）, X-ray diffractometry （XRD） and transmission electron microscopy （TEM）. It is revealed that Sc and Zr are completely dissolved into the supersaturated solid solution in as-cast ingot, but grain refinement is not observed. Coffee-bean-like AI3（Sc, Zr） particles deposit during homogenization of ingot induce an increase in hardness. Al3（Sc, Zr） particles are slightly coarsened in as-solution samples, but they still maintain coherent to matrix, which indicates a high thermal stability of these particles. Good coherency ofAl3（Sc, Zr） particles makes some benefits for inhibiting recrystallization and reserving work-hardening.

Effects of pre-precipitation of Cr_2N on microstructures and properties of high nitrogen stainless steel

Aging precipitation and solid solution heat treatment were carried out on three steels which have chromium content of 18%, manganese content of 12%, 15%, 18%, and nitrogen content of 0.43%, 0.53%, 0.67%, respectively. The mechanisms of precipitation and solid solution of high nitrogen anstenitic stainless steel were studied using the scanning electron microscopy, transmission electron microscopy, electron probe micro analysis and mechanical testing. The results show that, Cr2N is the primary precipitate in the tested stainless steels instead of Cr23C6. Cr2N nucleates at austenitic grain boundaries and grows towards inner grains with a lameUar morphology. By means of pre-precipitation of Cr2N at 800 ~C, the microstructure of the steels at solid solution state can be refined, thus improving the strength and plasticity. After the proposed treatment, the tensile strength, the proof strength and the elongation of the tested steel reach 881 MPa, 542 MPa and 54%, respectively.

Catalytic graphitization of Mo-B-doped polyacrylonitrile(PAN)-based carbon fibers

A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.

Fracture toughness and fatigue crack growth analysis of 7050-T7451 alloy thick plate with different thicknesses

The strength, fracture toughness and fatigue crack growth resistance of 7050-T7451 aluminum alloy plate with different thicknesses （35 mm and 160 ram） were investigated by means of optical microscope, scanning electron microscope and transmission electron microscope. The results show that thicker plate has lower strength and fracture toughness but higher fatigue crack growth resistance, by comparison to the thinner plate. The drop of strength is mainly attributed to grain coarsening in the thicker plate, and the increased degree of recrystallization results in the loss of Kio However, the coarsened grains in the thicker plate make cracks deflected and closure effect enhanced due to surface roughness increased. For both of plates, in the fracture surface subjected plain strain, a transition from transgranular dimpled fracture to intergranular dimpled fracture is observed during the fracture process.

Influences of melt spinning on electrochemical hydrogen storage performance of nanocrystalline and amorphous Mg_2Ni-type alloys

In order to improve the electrochemical hydrogen storage performance of the Mg2Ni-type electrode alloys, Mg in the alloy was partially substituted by La, and the nanocrystalline and amorphous Mg2Ni-type Mg20-xLaxNi10 （x-=0, 2） alloys were synthesized by melt-spinning technique. The microstructures of the as-spun alloys were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The electrochemical hydrogen storage properties of the experimental alloys were tested. The results show that no amorphous phase is detected in the as-spun Mg20Ni10 alloy, but the as-spun Mg18La2Ni10 alloy holds a major amorphous phase. As La content increases from 0 to 2, the maximum discharge capacity of the as-spun （20 m/s） alloys rises from 96.5 to 387.1 mA.h/g, and the capacity retaining rate （S20） at the 20th cycle grows from 31.3% to 71.7%. Melt-spinning engenders an impactful effect on the electrochemical hydrogen storage performances of the alloys. With the increase in the spinning rate from 0 to 30 m/s, the maximum discharge capacity increases from 30.3 to 135.5 mA.h/g for the Mg20Ni10 alloy, and from 197.2 to 406.5 mA-h/g for the Mg18La2Ni10 alloy. The capacity retaining rate （S20） of the Mg2oNi10 alloy at the 20th cycle slightly falls from 36.7% to 27.1%, but it markedly mounts up from 37.3% to 78.3% for the Mg18La2Ni10 alloy.

Deformation behavior of explosive detonation in electroformed nickel liner of shaped charge with nano-sized grains

Nickel liner of shaped charge with nano-sized grains was prepared by electroforming technique and the ultra-highstrain-rate deformation was performed by explosive detonation.The as-electroformed and post-deformed microstructures of electroformed nickel liner of shaped charge were observed by optical metallography(OM),scanning electron microscopy(SEM) and transmission electron microscopy(TEM) and the orientation distribution of the grains was analyzed by electron backscattering pattern(EBSP) technique.Both melting phenomenon in the jet fragment and recovery and recrystallization in the slug after ultra-high-strain-rate deformation were observed.The research evidence shows that dynamic recovery and recrystallization play an important role in ultra-high-strain-rate deformation for electroformed nickel liner of shaped charge with nano-sized grain.

Fast Evaluation of Degradation Degree of Organic Coatings by Analyzing Electrochemical Impedance Spectroscopy Data

The degradation coefficient is proposed to evaluate the degradation degree of organic coatings by directly anaIyzing the Bode plots of the electrochemical impedance spectroscopy （EIS） data. This paper investigated the degradation of phenolic epoxy coating/tinplate system by EIS and the degradation coefficient value, which correlates well with the results of breakpoint frequency and variation of phase angle at 10 Hz. Furthermore, the degradation process was confirmed by scanning electron microscope （SEM） and scanning probe microscopy （SPM）. It is concluded that degradation coefficient can be used for the fast evaluation of degradation degree of organic coatings in practical appli- cations.