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Twin Growth and Texture Evolution in an Extruded AM30 Magnesium Alloy during Compression

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Journal of Materials Science & Technology 2014年第9期30卷 884-887页

作者： d.Sarker J.Friedman d.l.Chen department of Mechanical and Industrial Engineering Ryerson University 350 Victoria StreetTorontoOntario M5B 2K3 Canada

The aim of this study was to examine and quantify the growth of extension twins and the associated texture change in an extruded AM30 magnesium alloy during compression along the extrusion direction. Three stages of twin growth with increasing strain were observed due to twin-dislocation interactions, together with increasing texture volume fraction of {1210}〈0001〉 and {01- 10}〈0001〉 components. Stage I was characterized by a relatively slow and gradually accelerating growth. A steady-state twin growth was reached in stage II, where the twin width increased linearly with increasing strain. Stage III twin growth became decelerated, exhibiting a plateau-like character.

关键词： Magnesium alloy Compressive deformation Twinning Twin growth Texture

de-twinning and Texture Change in an Extruded AM30 Magnesium Alloy during Compression along Normal direction

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Journal of Materials Science & Technology 2015年第3期31卷 264-268页

作者： d.Sarker J.Friedman d.l.Chen department of Mechanical and Industrial Engineering Ryerson University

Twinning and de-twinning are the salient deformation mechanisms in hexagonal close-packed(hcp)metals. The aim of this study was to examine and quantify the de-twinning process involving a reversible motion of twin boundaries in an extruded AM30 magnesium alloy after re-compression along the normal direction(Nd) of pre-compressed samples along the extrusion direction(Ed). {1012} extension twins were first introduced at a compressive strain of 3.7% along the Ed. The subsequent compressive deformation along the Nd induced a gradual shrinkage of twins with increasing cumulative true strain,and the complete de-twinning occurred at a strain of ~7.7%. The twin width decreased linearly with increasing true strain. Texture measurements verified the rotation of c-axes of hcp unit cells towards the anti-compression direction due to {1012} extension twinning after compression along the Ed, and a gradual return of c-axes to the initial orientation due to twin shrinking or de-twinning during the following compression along the Nd. The {1012} twinning corresponded to the formation of new texture components C{1210} and d{0110} and a decrease in the initial texture components A{0001} and B{0001}, while the twin shrinking or de-twinning was characterized by a gradual vanishing of components C{1210} and d{0110} and an increase in the components A{0001} and B{0001}.

关键词： Magnesium alloy Compressive deformation Twinning d

Macrophage migration inhibitory factor gene polymorphisms in inflammatory bowel disease: An association study in New Zealand Caucasians and meta-analysis

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world Journal of Gastroenterology 2013年第39期19卷 6656-6664页

作者： James d Falvey Robert w Bentley Tony R Merriman Mark B Hampton Murray l Barclay Richard B Gearry Rebecca l Roberts department of Medicine University of OtagoChristchurch 8011New Zealand department of Gastroenterology Christchurch HospitalChristchurch 8011New Zealand department of Biochemistry University of OtagoDunedin 9054New Zealand department of Pathology University of OtagoChristchurch 8011New Zealand department of Surgical Sciences Dunedin School of MedicineDunedin 9054New Zealand

AIM:To investigate the association of macrophage migration inhibitory factor(MIF)promoter polymorphisms with inflammatory bowel disease(IBd)***:One thousand and six New Zealand Caucasian cases and 540 Caucasian controls were genotyped for the MIF SNP-173G>C(rs755622)and the repeat polymorphism CATT5-8(rs5844572)using a predesigned TaqMan SNP assay and capillary electrophoresis,*** were analysed for single site and haplotype association with IBd risk and ***-analysis was employed,to assess cumulative evidence of association of MIF-173G>C with *** published genotype data for MIF-173G>C in IBd were identified using PubMed and subsequently searching the references of all PubMed-identified *** genotypes for MIF-173G>C were generated from the wellcome Trust Case Control Consortium(and National Institute of diabetes and digestive and Kidney diseases).Separate meta-analyses were performed on Caucasian Crohn’s disease(Cd)(3863 patients,6031controls),Caucasian ulcerative colitis(UC)(1260 patients,1987 controls),and East Asian UC(416 patients and 789 controls)datasets using the Mantel-Haenszel *** New Zealand dataset had 93%power,and the meta-analyses had 100%power to detect an effect size of OR=1.40 atα=0.05,***:In our New Zealand dataset,single-site analysis found no evidence of association of MIF polymorphisms with overall risk of Cd,UC,and IBd or disease phenotype(all P values>0.05).Haplotype analysis found the CATT5/-173C haplotype occurred at a higher frequency in New Zealand controls compared to IBd patients(0.6 vs 0.01;P=0.03,OR=0.22;95%CI:0.05-0.99),but this association did not survive bonferroni ***-analysis of our New Zealand MIF-173G>C data with data from seven additional Caucasian datasets using a random effects model found no association of MIF polymorphisms with Cd,UC,or overall ***,meta-analysis of all published MIF-173G>C data from East Asian datasets(416UC patients

关键词： Crohn’s disease Ulcerative colitis Migration inhibitory factor rs755622 rs5844572 Genetic association study

In-situ loading neutron-diffraction studies of a cobalt-based superalloy

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中国有色金属学会会刊：英文版 2006年第A2期16卷 144-148页

作者： M. l. BENSON P. K lIAw H. CHOO T. A. SAlEH d. w. BROwN M. R. dAYMONd X. l. wANG A. d. STOICA E. C. OlIVER d. l. KlARSTROM department of Materials Science and Engineering University of Tennessee Knoxville TN 37996 USA Metals and Ceramics division Oak Ridge National Laboratory Oak Ridge TN 37831 USA los Alamos Neutron Science Center Los Alamos National Laboratory Los Alamos NM 87545 USA department of Mechanical and Materials Engineering Queen＇s University Kingston ON K7L3N6 Canada Spallation Neutron Source Oak Ridge National Laboratory Oak Ridge TN 37831 USA ISIS Pulsed Neutron and Muon Source Rutherford-Appleton Laboratory Chilton Didcot OX 11 0QX UK Haynes International Inc Kokomo IN 46904 USA

UlTIMET® alloy is a cobalt-based superalloy that undergoes a deformation-induced phase transformation from a face-centered-cubic (fcc) phase to a hexagonal-close-packed (hcp) phase. The transformation was studied during monotonic loading, stress-controlled high-cycle fatigue (HCF) and strain-controlled low-cycle fatigue (lCF). The HCF was performed at a maximum stress of σmax=840 MPa and a minimum stress of σmin=84 MPa, while the tensile experiment was terminated after reaching σmax=890 MPa. The lCF was performed at a maximum strain of σmax=1.25% and a minimum strain of σmin=-1.25%. The monotonic-loading experiment results reveal that the hcp phase forms after reaching the yield stress. during HCF, the hexagonal phase forms immediately upon the first fatigue cycle, with no further change in structure upon subsequent deformation. In contrast to HCF, the hcp phase forms gradually during lCF. In fact, fatigue cycle 12 is reached before the hcp phase is resolved by neutron diffraction. diffraction patterns from subsequent fatigue cycles reveal that the hcp phase continues to accumulate as lCF progresses. These observations can be related to the input of mechanical energy during different loading modes.

关键词：钴基高温合金现场加载中子衍射 fcc hcp 相变

A Preliminary Investigation of the Possible Hypoglycemic Activity of Hibiscus rosa-sinensis

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Biomedical and Environmental Sciences 1999年第3期12卷 222-226页

作者： ARCHANASACHdEwA l·d·KHEMANI departmentofChemistry FacultyofScienceDayalbaghEducationalInstituteDayalbagh departmentofChemistry

The hypoglycemic activity of an ethanol extract of Hibiscus rosa-sinsnsis was studied in glucose located rats. Afer a single dose of the extract, a slight but insignificant hypoglycemic effect was observed at 30 and 90 min. At 120 min it was mild but significant. After repeated administration of the extract (once a day for seven consecutive days) a statistically significant (P duction in blood glucose levels was observed at 30, 90 and 120 min after glucose loading. The average hypoglycemic activity, after repeated administration of 250 mg kg-1 leaf extract was 81 %, under similar conditions average activity of tolbutamide was 96%. At 250 mg·kg-1 the efficacy of the extract was found to be 84% of tolbutawhde (100mg·kg- 1 ). Repeated treatment of animals either with tolbutandde a sulphonylurea or H. rosa-sinensis caused a 2-3-fold improvement in glucose tolerance as compared to those receiving only once. These data suggest that the leaf extract acts like tolbutamide and the meehanism of action may be a stimulation of pancreatic hata cells to produce more insulin or an increase of the glycogen deposition in liver. It appeare that the active principle in the tested extract has the sulphonylurea Skeleton in which -SO2-NH-CO- group and the substituents (S1 and S2) may be the possible active sites responsible for its hypolycemic activity.

关键词： Hypoglycemic Agents Animals disease Models, Animal Glucose Tolerance Test Hyperglycemia Male Plant Extracts Rats

EFFECTS OF HEAT TREATMENT ON THE THERMAl EXPANSION BEHAVIOR OF SiC wHISKER REINFORCEd AlUMINUM COMPOSITE

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Acta Metallurgica Sinica(English letters) 2001年第3期14卷 163-170页

作者： M. Hu, w.d. Fei, w.l. li and C.K. Yao (School of Materials Science and Technology, Harbin Institute of Technology, Harbin 150001, China) Sch. of Mat. Sci. and Technol. Harbin Inst. of Technol. Harbin 150001 China

The thermal expansion behaviors of commercially-available SiC whisker reinforced pure aluminum composites subjected to different heat treatments were studied. The results indicated that the thermal expansion behaviors were greatly affected by heat treatment. To explain the results, the microstructures and thermal mismatch stresses in the matrix of the composite were examined by the transmission electron microscope and X-ray diffraction, respectively. The results show that the dislocation density and thermal mismatch stresses in the matrix of the composites water-quenched from 600°C are much higher than those of the composite slowly cooled from 600°C. The analysis suggests that the coefficients of thermal expansion (CTE) are closely related to the change of thermal mismatch stresses and the yield strength of the matrix of the composite. The comparison of the coefficients of thermal expansion between experiments and calculations suggests that the temperature behaviors of CTE of SiC/Al composite agree better with those of Kerner's model within lower temperature range.

关键词： Aluminum Crystal whiskers Heat treatment Silicon carbide Thermal expansion

THERMAl STABIlITY OF NON-EQUIlIBRIUS MICROSTRUCTURE IN MICROAllOYEd STEEl dURING REHEATING

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Acta Metallurgica Sinica(English letters) 2007年第5期20卷 313-326页

作者： H.B. wu H.T. Jiang S.w. Yang d. Tang X.l. He National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing Beijing 100083 China dept. of Materials Physics University of Science and Technology Beijing Beijing 100083 China

Cooled in water after isothermal relaxation of deformed austenite for different times, an Nb-bearing microalloyed steel always exhibits synthetic microstructures, in which bainitic ferrite ,dominates. dislocation configurations and distributions of strain induced precipitates inside bainitic ferrite of samples relaxed for different times were distinct. when compared with the austenite model steel, which maintained fcc structure even at room temperature, the strain induced precipitates were not found in the sample without relaxation whereas these were distributed outside dislocations in sample relaxed for 1000s. Most of the strain induced precipitates distribute along dislocations and pin dislocations in sample relaxed for appropriate time. After bainitic transformation, the dislocations formed in deformed austenite remain to be pinned by the precipitates. when these samples were reheated to and held at 650 or 700℃, the non-equilibrloas microstructures tended to evolve into equilibrioas ones. The sample relaxed for 60s displayed the highest thermo-stability, whereas microstructure evolution was the quickest in the sample relaxed for 1000s even though it was the softest prior to reheating. dislocations inside laths got rid of pinning of precipitates, and their polygonization became the precursor to the evolution of microstructures during reheated and held, followed by gradual disappearance of lath boundaries caused by dislocation climbing. Finally, recrystallization occurred and polygonal ferrite appeared. By hardness measurement, it was found that softening is not a single process occurring during reheated, in which hardness fluctuates with time. There were two peaks in the hardness-time curve of each sample having undergone relaxation, while single peak occured in the curve of the sample not being relaxed. These results indicated that the thermo-stability of microstructures was determined by their history of formation to a considerable degree.

关键词： bainite reheating strain induced precipitate pinning microstructures evolution

Alcohol-induced protein hyperacetylation: Mechanisms and consequences

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world Journal of Gastroenterology 2009年第10期15卷 1219-1230页

作者： Blythe d Shepard Pamela l Tuma department of Biology The Catholic University of America 620 Michigan Avenue NE Washington DC 20064 United States

Although the clinical manifestations of alcoholic liver disease are well-described, little is known about the molecular basis of liver injury. Recent studies have indicated that ethanol exposure induces global protein hyperacetylationo This reversible, post- translational modification on the E-amino groups of lysine residues has been shown to modulate multiple, diverse cellular processes ranging from transcriptional activation to microtubule stability. Thus, alcohol- induced protein hyperacetylation likely leads to major physiological consequences that contribute to alcohol-induced hepatotoxicity. lysine acetylation is controlled by the activities of two opposing enzymes, histone acetyltransferases and histone deacetylases. Currently, efforts are aimed at determining which enzymes are responsible for the increased acetylation of specific substrates. However, the greater challenge will be to determine the physiological ramifications of protein hyperacetylation and how they might contribute to the progression of liver disease. In this review, we will first list and discuss the proteins known to be hyperacetylated in the presence of ethanol. we will then describe what is known about the mechanisms leading to increased protein acetylation and how hyperacetylation may perturb hepatic function.

关键词： Ethanol Hepatotoxicity Acetylation deacetylases Acetyltransferases

Alcohol-induced alterations of the hepatocyte cytoskeleton

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world Journal of Gastroenterology 2010年第11期16卷 1358-1365页

作者： Blythe d Shepard Pamela l Tuma department of Biology The Catholic University of America

The hepatocyte cytoskeleton consists of three fi lamentous networks: microtubules, actin microfi laments and keratin intermediate filaments. Because of the abundance of the proteins that comprise each system and the central role each network plays in a variety of cellular processes, the three fi lament systems have been the focus of a host of studies aimed at understanding the progression of alcohol-induced liver injury. In this review, we will briefly discuss the hepatic organization of each cytoskeletal network and highlight some components of each system. we will also describe what is known about ethanol-induced changes in the dynamics and distributions of each cytoskeletal system and discuss what is known about changes in protein expression levels and post-translational modifi cations. Finally, we will describe the possible consequences of these cytoskeletal alterations on hepatocyte function and how they might contribute to the progression of liver disease.

关键词： Ethanol Hepatotoxicity Tubulin Actin Keratin