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Taxol Determination from Pestalotiopsis pauciseta, a Fungal Endophyte of a Medicinal Plant

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生物工程学报 2008年第8期24卷 1433-1438页

作者： Gangadevi V Murugan M Muthumary j Centre for Advanced Studies in Botany University of Madras Guindy Campus Chennai 600025 Tamil Nadu India.

Taxol is the most effective antitumor agent developed in the past three *** has been used for effective treatment of a variety of cancers.A taxol-producing endophytic fungus Pestalotiopsis pauciseta(strain CHP-11) was isolated from the leaves of Cardiospermum helicacabum and screened for taxol *** fungus was identified based on the morphology of the fungal culture and the characteristics of the spores and screened for taxol *** amount of taxol produced by this endophytic fungus was quantified by HPLC and it produced 113.3 μg/L,thus the fungus can serve as a potential material for fungus engineering to improve taxol *** fungal taxol also had strong anticancer activity against some cancer cells viz.,BT 220,H116,Int 407,HL 251 and HLK 210 tested by Apoptotic assay and it is indicated that with the increase of taxol concentration from 0.005-0.05 μmol/L,taxol induced increased cell death through apoptosis.

关键词：内部寄生植物抗癌抗菌素红豆杉醇癌症

Deformation behavior of laser bending of circular sheet metal

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Chinese Optics Letters 2011年第5期9卷 47-51页

作者： Q.Nadeem S.j.Na Department of Mechanical Engineering KAIST

The application of a thermal source in non-contact forming of sheet metal has long been used. However, the replacement of this thermal source with a laser beam promises much greater controllability of the process. This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and manufacturing industries, as well as the rapid manufacturing of prototypes and adjustment of misaligned components. Forming is made possible through laser-induced non-uniform thermal stresses. In this letter, we use the geometrical transition from rectangular to circle-shaped specimen and ring-shaped specimen to observe the effect of geometry on deformation in laser forming. We conduct a series of experiments on a wide range of specimen geometries. The reasons for this behavior are also analyzed. Experimental results are compared with simulated values using the software ABAQUS. The utilization of line energy is found to be higher in the case of laser forming along linear irradiation than along curved ones. We also analyze the effect of strain hindrance. The findings of the study may be useful for the inverse problem, which involves acquiring the process parameters for a known target shape of a wide range of complex shape geometries.

关键词： Deformation behavior of laser bending of circular sheet metal

Shock compression and spallation damage of high-entropy alloy Al_(0.1)CoCrFeNi

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journal of Materials Science & Technology 2022年第33期128卷 1-9页

作者： N.B.Zhang j.Xu Z.D.Feng Y.F.Sun j.Y.Huang X.j.Zhao X.H.Yao S.Chen L.Lu S.N.Luo Key Laboratory of Advanced Technologies of Materials Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China The Peac Institute of Multiscale Sciences Chengdu 610031China Department of Engineering Mechanics South China University of TechnologyGuangzhou 510641China

Shock compression and spallation damage of a face-center cubic phase high-entropy alloy(HEA)Al_(0.1)CoCrFeNi were investigated via plate impact experiments along with free surface velocity *** samples were characterized with transmission electron microscopy and electron backscatter *** Hugoniot equation of state and spall strength at different impact strengths were *** exists a power-law relation between spall strength and strain *** spall strength of Al_(0.1)CoCrFeNi HEA is about 50%higher than those of previously studied HEAs and comparable to those widely applied structural stainless steels at the same shock *** glide and stacking faults are the important deformation mechanisms in the Al_(0.1)CoCrFeNi *** are only observed at high shock *** in the Al_(0.1)CoCrFeNi HEA is ductile in *** are nucleated preferentially in grain interiors,and the intragranular voids show a strong dependence on grain boundary misorientation and peak stress.

关键词： Al_(0.1)CoCrFeNi High-entropy alloy Hugoniot Spall damage Microstructure

A DUCTILE FRACTURE CRITERION BASED ON THREEDIMENSIONAL VOID MODEL

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Acta Metallurgica Sinica(English Letters) 2008年第3期21卷 227-234页

作者： j.K. Huang X.H. Dong National Die ＆ Mould CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030China

A fracture criterion derived from a microscopic point of view is proposed and has proved to be effective in the analysis of uniaxial tension. On the one hand, a method of predicting a ductile fracture is proposed using a three-dimensional void model and the assumption of velocity discontinuity. The relationship between the void volume fraction and the critical strain to fracture, calculated with the help of the new model, shows the same tendency as that obtained from the modified Thomason model. On the other hand, the mechanical and metallographic analyses of the uniaxial tension experiment are performed using four kinds of carbon steel. The relationship between the void volume fraction and the critical strain to fracture, calculated from the new model, agrees better with the result obtained from the experiment, rather than that calculated by the modified Thomason model, which confirms the validity of the ductile fracture criterion based on the three-dimensional void model.

关键词： Fracture criterion Uniaxial tension Velocity discontinuity Mechanical and metallographic analyses

A MICROMECHANICAL MODEL FOR γ-TiAl BASE PST CRYSTALS

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Acta Metallurgica Sinica(English Letters) 2005年第6期18卷 686-694页

作者： j.L. Su G.K. Hu School of Mechanics-Electrics Engineering Fujian Agriculture and Forestry University Fuzhou 350002 China Department of Applied Mechanics Beijing Institute of Technology Beijing 100081 China

An analytical micromechanical method is proposed to examine the dependence of plastic deformation on the microstructure for a PST crystal. The sub-domain microstructure of the γ phase and the effect of the α2 phase are taken into account by a proper micromechanical formulation, the dislocation slip and twinning deformation mechanisms are considered in the context of crystal plasticity. The model can well predict the dependence of stress-strain relations on loading angle with respect to the microstructure. The influence of the twinning and lamellar spacing on the deformation behavior and biaxial yield surfaces for PST crystals are also examined.

关键词： TiAI alloy crystal plasticity micromechanical model yield surface

A NOVEL METHOD FOR EVALUATING PLANE STRESS DYNAMIC FRACTURE TOUGHNESS OF 0Cr18Ni10Ti STAINLESS STEEL WELDED jOINTS

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Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 303-312页

作者： Z.j. Xu Y.L. Li School of Aeronautics Northwestern Polytechnical University Xi＇an 710072 China

A novel method was proposed for the evaluation of Mode I dynamic fracture toughness （DFT） under plane stress and small scale yielding conditions for welded joints of stainless steel （SS）, 0Cr18Ni10Ti. In a hybrid experimental-numerical approach, the experiments were carried out on the Hopkinson pressure bar apparatus, and three dimensional （3D） transient numerical simulations were performed by a finite element （FE） computer program. Macroscopical plastic deformation was observed at the loading and supporting points, on the specimens, after the test, which could cause a large error if omitted in the numerical simulation. Therefore, elustic-viscoplustic analysis was performed on the specimen by adopting the johnson-Cook （j-C） model to describe the rate-dependent plastic flow behavior of the material. The material heterogeneity in the mismatched welded joints, induced by the difference in the base metal （BM） and the weld metal （WM） in yield stress, has also been taken into consideration by using the j-C models separately. Good accordance was obtained between the experimental and the computational results by the present approach. The relationship between plane stress DFT and loading rate was also obtained on the order of 108 MPa.m^1/2.s^-1.

关键词： 0Cr18Ni10Ti Welded joint High strain rate Dynamic fracture Plane stress

MECHANICS OF RELAXING SiGe ISLANDS ON A VISCOUS GLASS

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Acta Mechanica Sinica 2002年第5期18卷 441-456页

作者： R. Huang H. Yin j. Liang j. C. Sturm K. D. Hobart Z. Suo Mechanical and Aerospace Engineering Department and Princeton Materials Institute Princeton University Princeton USA Department of Aerospace Engineering and Engineering Mechanics University of Texas at Austin Austin USA Center for Photonics and Optoelectronic Materials and Department of Electrical Enineering Princeton University Princeton USA Naval Research Laboratory Washington DC USA

A process has been developed recently to fabricate a structure com- prising,from top to bottom,a SiGe thin film,a glass layer,and a Si *** SiGe film is a perfect crystal,and is under biaxial *** SiGe film is patterned into *** annealing,the glass flows and the islands *** resulting strain-free islands are used as substrates,to grow epitaxial optoelectronic *** article describes a series of studies on the annealing process,combining experiment and theory.A small island relaxes by expansion,starting at the edges and diffusing to the center.A large island wrinkles before the expansion reaches the *** some time,the wrinkles either disappear,or cause the island to fracture. We model the island as an elastic plate,and the glass layer as a viscous *** strains in the islands are measured by X-ray diffraction and Raman spectroscopy,and the wrinkle amplitudes by atomic force *** data are compared with the theoretical *** determine the conditions under which the islands relax by expansion without significant wrinkling,and demonstrate that a cap layer suppresses wrinkles,relaxing a large island crack-free.

关键词： semiconductor fabrication stress relaxation viscous flow elastic plate fracture

Direct strain evaluation method for laboratory-based pillar performance

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journal of Rock Mechanics and Geotechnical Engineering 2019年第4期11卷 860-866页

作者： K.V.jessu A.j.S.Spearing WA School of Mines Curtin University

Pillar stability is one of important aspects for underground ***,the stability of the pillars is evaluated empirically based on case studies and site-specific rock mass conditions in *** the empirical approach applicability can sometimes be *** numerical-based approaches are potentially more useful as parametric studies can be undertaken and,if calibrated,can be more *** empirical and numerical approaches are dependent on the strength evaluation of the pillars while the strain developing in the pillars is seldom taken into *** this paper,gypsum and sandstone samples were tested in laboratory with different width-to-height ratios (W/H) to adapt the strain evaluation method to the laboratory-based pillars.A correlation was then developed between the strain and the width-to-height ratio for pillar monitoring *** on the results,a flowchart was created to conduct back analysis for the existing pillars to evaluate their stability and design new pillars,considering the strain analysis of the existing pillars with the W/H ratios modelled.

关键词： Failure strain Critical strain Pillars Width-to-height ratio Stability

Evaluation of Microstructure and Magnetic Properties in Non-oriented Electrical Steel strained by Tension

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journal of Iron and Steel Research International 2016年第2期23卷 166-170页

作者： j.SALINAS B. A.SALINAS R. Engineering Metallurgical Research Center and Advanced Studies of National Polytechnic Institute

The effects of deformation on the microstructure and magnetic properties of non oriented electrical steels were investigated. Box annealed electrical steel sheets were deformed by tension at four different strains： 3%, 8%, 12 % and 25 % The internal grain misorientation caused by tensile deformation was measured by electron backscat- tering diffraction （EBSD） with grain orientation spread （GOS） as an indicator of the lattice distortion. The experi- mental results showed that the average GOS value increases with the strain. The microstructure and crystallographic texture of deformed samples did not show a significant change in samples strained below 25 %. However, the mag- netic properties were strongly affected： coercivity was directly proportional to the square root of the GOS value and energy losses increased as the strain level was increased.

关键词： non-oriented electrical steel tensile deformation internal misorientation magnetic property EBSD