Sample records for blattabacterium strain bge

  1. Comparative genomics of Blattabacterium cuenoti: the frozen legacy of an ancient endosymbiont genome.

    Patiño-Navarrete, Rafael; Moya, Andrés; Latorre, Amparo; Peretó, Juli


    Many insect species have established long-term symbiotic relationships with intracellular bacteria. Symbiosis with bacteria has provided insects with novel ecological capabilities, which have allowed them colonize previously unexplored niches. Despite its importance to the understanding of the emergence of biological complexity, the evolution of symbiotic relationships remains hitherto a mystery in evolutionary biology. In this study, we contribute to the investigation of the evolutionary leaps enabled by mutualistic symbioses by sequencing the genome of Blattabacterium cuenoti, primary endosymbiont of the omnivorous cockroach Blatta orientalis, and one of the most ancient symbiotic associations. We perform comparative analyses between the Blattabacterium cuenoti genome and that of previously sequenced endosymbionts, namely those from the omnivorous hosts the Blattella germanica (Blattelidae) and Periplaneta americana (Blattidae), and the endosymbionts harbored by two wood-feeding hosts, the subsocial cockroach Cryptocercus punctulatus (Cryptocercidae) and the termite Mastotermes darwiniensis (Termitidae). Our study shows a remarkable evolutionary stasis of this symbiotic system throughout the evolutionary history of cockroaches and the deepest branching termite M. darwiniensis, in terms of not only chromosome architecture but also gene content, as revealed by the striking conservation of the Blattabacterium core genome. Importantly, the architecture of central metabolic network inferred from the endosymbiont genomes was established very early in Blattabacterium evolutionary history and could be an outcome of the essential role played by this endosymbiont in the host's nitrogen economy. PMID:23355305

  2. Two new saponins from Anemarrhena asphodeloides Bge

    Ying Peng; Yu Jing Zhang; Zhi Qiang Ma; Wei San Pan; Yu Qing Sun; Shao Jiang Song


    Two new saponins 3-O-β-D-glucopyranosyl (1 → 2)-β-D-mannopyranosyl sarsasapogenin, named timosaponin A Ⅳ(1) and(5β, 25S)-26-O-β-D-glucopyranosyl-furost-20(22)-en-3,26-diol-3-O-β-D-glucopyranosyl (1→ 4) glucopyranosyl (1 → 2)-β-D-galacopyranoside, named timosaponin B Ⅳ(2), were isolated by silica gel column chromatography and preparative HPLC from Anemarrhena asphodeloides Bge. Their structures were elucidated by chemical characters and spectroscopic analysis.

  3. Maintenance of essential amino acid synthesis pathways in the Blattabacterium cuenoti symbiont of a wood-feeding cockroach.

    Tokuda, Gaku; Elbourne, Liam D H; Kinjo, Yukihiro; Saitoh, Seikoh; Sabree, Zakee; Hojo, Masaru; Yamada, Akinori; Hayashi, Yoshinobu; Shigenobu, Shuji; Bandi, Claudio; Paulsen, Ian T; Watanabe, Hirofumi; Lo, Nathan


    In addition to harbouring intestinal symbionts, some animal species also possess intracellular symbiotic microbes. The relative contributions of gut-resident and intracellular symbionts to host metabolism, and how they coevolve are not well understood. Cockroaches and the termite Mastotermes darwiniensis present a unique opportunity to examine the evolution of spatially separated symbionts, as they harbour gut symbionts and the intracellular symbiont Blattabacterium cuenoti. The genomes of B. cuenoti from M. darwiniensis and the social wood-feeding cockroach Cryptocercus punctulatus are each missing most of the pathways for the synthesis of essential amino acids found in the genomes of relatives from non-wood-feeding hosts. Hypotheses to explain this pathway degradation include: (i) feeding on microbes present in rotting wood by ancestral hosts; (ii) the evolution of high-fidelity transfer of gut microbes via social behaviour. To test these hypotheses, we sequenced the B. cuenoti genome of a third wood-feeding species, the phylogenetically distant and non-social Panesthia angustipennis. We show that host wood-feeding does not necessarily lead to degradation of essential amino acid synthesis pathways in B. cuenoti, and argue that ancestral high-fidelity transfer of gut microbes best explains their loss in strains from M. darwiniensis and C. punctulatus. PMID:23515978

  4. Anti-inflammatory effects and structure elucidation of two new compounds from Astragalus membranaceus (Fisch) Bge. var. mongholicus (Bge) Hsiao

    Wang, Qing-Hu; Han, Na-Ren-Chao-Ke-Tu; Dai, Na-Yin-Tai; Wang, Xiu-Lan; Ao, Wu-Li-Ji


    Phytochemical study of the ethanol extract of Astragalus membranaceus (Fisch) Bge. var. mongholicus (Bge) Hsiao resulted to the isolation of two new compounds, 1-hydroxy-5-methylolbenzol-2-O-β-D-glucoside (1) and (3R, 4R)-4,7-hydroxy-2‧,3‧-dimethoxyisoflavane-4‧-O-β-D-glucoside (2). The structure of the isolated compounds were elucidated on the basis of the spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR techniques, and by comparison with those reported in the literature. The new compounds were investigated for its effect against inflammation induced by egg-albumin and carrageenan in rats.




    Two novel natural products, namely pinnatifida C, pinnatifida D, were isolated from the leaves of Crataegus pinnatifida Bge.var.rnajor N.E.Br. Their structures were elucidated by the spectro scopic analysis and chemical evidence.

  6. Synthesis and investigation of rare earth boratogermanates LnBGeO5

    By the method of solid phase reactions from rare earth, germanium and boric acid oxides, rare earth borates and germanates, as well as from products of coprecipitation from solutions, boratogermanates LnBGeO5 (Ln-La-Er, Y) have been synthesized. It is ascertained that LnBGeO5 compounds prepared by means of solid phase interaction, form two structural groups: 1-Ln-La, 2-Ln-Nd-Er, Y. To the first group neodimium, samarium and europium boratogermanates, synthesized in metastable state by the annealing of coprecipitation products from solutions, have also been referred. Compounds LnBGeO5 od structural group 1 are isostructural to natural mineral stillwellite (La,Ce)BSiO5. Temperatures and melting character of boratogermanates LnBGeO5 (Ln-La-Tb), temperatures of thermal decomposition in solid state of compounds LnBGeO5 (Ln-Dy-Er, Y), and phase composition of the products formed are determined

  7. Purification and partial genome characterization of the bacterial endosymbiont Blattabacterium cuenoti from the fat bodies of cockroaches

    Yamada Akinori


    Full Text Available Abstract Background Symbiotic relationships between intracellular bacteria and eukaryotes are widespread in nature. Genome sequencing of the bacterial partner has provided a number of key insights into the basis of these symbioses. A challenging aspect of sequencing symbiont genomes is separating the bacteria from the host tissues. In the present study, we describe a simple method of endosymbiont purification from complex environment, using Blattabacterium cuenoti inhabiting in cockroaches as a model system. Findings B. cuenoti cells were successfully purified from the fat bodies of the cockroach Panesthia angustipennis by a combination of slow- and fast-speed centrifugal fractionations, nylon-membrane filtration, and centrifugation with Percoll solutions. We performed pulse-field electrophoresis, diagnostic PCR and random sequencing of the shoutgun library. These experiments confirmed minimal contamination of host and mitochondrial DNA. The genome size and the G+C content of B. cuenoti were inferred to be 650 kb and 32.1 ± 7.6%, respectively. Conclusion The present study showed successful purification and characterization of the genome of B. cuenoti. Our methodology should be applicable for future symbiont genome sequencing projects. An advantage of the present purification method is that each step is easily performed with ordinary microtubes and a microcentrifuge, and without DNase treatment.

  8. Optimal Extraction of Gallic Acid from Suaeda glauca Bge. Leaves and Enhanced Efficiency by Ionic Liquids

    Xin-Hong Wang; Chen Cai; Xue-Mei Li


    The ultrasound-assisted extraction (UAE) was initially applied to extract gallic acid from Suaeda glauca Bge. using 70% ethanol as extraction solvent. Temperature, liquid-solid ratio, and extraction time were optimized by response surface methodology (RSM), obtaining maximum levels of gallic acid (6.30 mg·g−1) at 51°C, 19.52 mL·g−1, and 42.68 min, respectively. The obtained model was statistically significant (p

  9. Space flight effects analysis of sp2 salvia miltiorrhiza bge · using srap marker

    In order to study the effects of space mutation of Salvia miltiorrhiza Bge., agronomic traits had been studied in SP2 by field investigation and SRAP. The results showed that the mutagenic effects of space flight were complicated and there were variant effect on different plants and different traits.146 alleles had been detected from 19 materials with 12 primer pairs. Jaccard's similarity coefficient ranged from 0.453 ∼ 0.867, the average was 0.648. (authors)

  10. Optimal Extraction of Gallic Acid from Suaeda glauca Bge. Leaves and Enhanced Efficiency by Ionic Liquids

    Xin-Hong Wang


    Full Text Available The ultrasound-assisted extraction (UAE was initially applied to extract gallic acid from Suaeda glauca Bge. using 70% ethanol as extraction solvent. Temperature, liquid-solid ratio, and extraction time were optimized by response surface methodology (RSM, obtaining maximum levels of gallic acid (6.30 mg·g−1 at 51°C, 19.52 mL·g−1, and 42.68 min, respectively. The obtained model was statistically significant (p<0.0001. The verification experiments at the optimum conditions yielded gallic acid for 6.21 mg·g−1. Subsequently, under optimal conditions, four ionic liquids were used to extract gallic acid from Suaeda glauca Bge. The results indicated that the presence of 1-hexyl-3-methylimidazolium chloride allowed increasing the EE of gallic acid up to 8.90 mg·g−1. This might be interpreted in terms of the molecular interaction between ionic liquid and gallic acid. The use of ionic liquids involves a stronger gallic acid extraction capacity than conventional organic volatile solvents. A promising alternative process is proposed for the extraction of gallic acid of Suaeda glauca Bge.

  11. Structures and phase transitions of PrBGeO5 in the temperature range 20-800 deg. C

    High-resolution neutron powder diffractometry has been used to characterize the structural phase transitions which occur in PrBGeO5 at 550 and 750 deg. C. The change in lattice parameters of the trigonal unit cell as a function of temperature, observed in the range from ambient to 800 deg. C, shows that the 550 deg. C transition is associated with an abrupt contraction of the unit cell volume. The crystal structure stable in the temperature interval between 550 and 750 deg. C is isomorphous with the stillwellite structure of LaBGeO5 in its polar variant stable up to 530 deg. C. The phase transition at 750 deg. C to a non-polar variant of the structure mimics the 530 deg. C transition in LaBGeO5. The structural parameters of these two PrBGeO5 phases have been refined from data taken at 650, 770 and 800 deg. C. The structure of the PrBGeO5 phase stable at ambient temperature gives rise to extra reflections not given by the stillwellite structure. These can be indexed on a triple cell with a' approx. √3a, c' approx. c and the structure has been determined and refined from a combination of neutron powder data and an ambient temperature single crystal x-ray diffraction study. (author)

  12. Antihyperglycemic and Antihyperlipidemic Effects of Fruit Aqueous Extract of Berberis integerrima Bge. in Streptozotocin-induced Diabetic Rats

    Ashraf, Hossein; Heidari, Reza; Nejati, Vahid


    Use of medicinal plants for attenuation of hyperglycemia and restoration of lipids disorder to normal level is clinically very important. The aim of present study was to evaluate the effects of Berberis integerrima Bge. fruit aqueous extract (BIFAE) on blood glucose and lipid profile in streptozotocin (STZ) - induced diabetic rats. The STZ-induced diabetic rats were treated by fruit aqueous extract of Berberis integerrima Bge. at doses (250 and 500 mg/Kg bw) and glibenclamide (0.6 mg/Kg bw) f...

  13. [Study of the fourth generation of Salvia miltiorrhiza Bge by XRF].

    Zhu, Yan-Ying; Guo, Xi-Hua; Wang, Zhi-Zhou; Guan, Ying


    X-ray fluorescence spectrum (XRF) analytic method was used to analyze and compare the contents and varieties of mineral elements in the ground group Salvia miltiorrhiza Bge, and the fourth generation Salvia miltiorrhiza Bge with space flight mutagenesis breeding in order to provide important basic data for selecting high quality breed and further research. The result indicates that the varieties of the main mineral elements in the two samples are the same basically, but Cu/Zn ratio is enhanced to 1.0, the contents of microelements Cr, Mn and Fe increase by 0.6, 0.5, and 0.3 times respectively compared with the ground group. To conclude, in the space group the contents and proportions of the mineral elements are improved and optimized. Xray fluorescence spectrum analytic method has many advantages, such as quickness, simplicity, high sensitivity, wide measure range, etc. The method can be used for quantitative element analysis and study of Chinese herbal medicines. PMID:20545179

  14. Two New C-glucoside Flavonoids from Leaves of Crataegus pinnatifida Bge.var.major N.E.Br.


    Two new C-glucoside flavonoids,namely 8-C-(-D-(2(-O-acetyl) glucofuranosyl apigenin and 3(-O-acetylvitexin,were isolated from leaves of Crataegus pinnatifida Bge.var.major N.E.Br..Their structures were elucidated by the spectroscopic means and chemical evidence.

  15. Volatile Components from Dracocephalum integrifolium Bge%全叶青兰挥发性成分

    刘建英; 王利平; 刘玉梅


    The composition and contents of volatile components from Dracocephalum integrifolium Bge. were analyzed by using headspace solid-phase microextraction ( HS-SPME) combined with gas chromatography-mass spectrometry(GC-MS) method. The results indicate that,with 6 min and 30 min headspace adsorption time, the volatile components were basically identical in terms of the main components except for their different proportion. The hydrocarbons (mainly terpenoids) were the major component in the volatile components from Dracocephalum integrifolium Bge. , which accounted for about 30% , the alcohol compounds for around 20% , others in descending order as esters, ketones, terpene oxides and aldehyde compounds. However,the content of such components as ether,amine and sulfur compounds was very low.%采用顶空固相微萃取结合色谱质谱技术分析了全叶青兰中挥发性成分的组成和含量.结果表明,6 min和30 min的顶空吸附时间所测得的全叶青兰中挥发性成分的组分基本一致,但各组分所占的比例有一定差异.全叶青兰挥发性成分中以萜烯类为主的碳氢化合物约占其总质量的50%,醇类化合物约占20%,其他成分的质量分数高低依次为酯、酮、萜烯氧化物和醛类化合物,醚、胺及含硫化合物等质量分数极低.

  16. Structural aspects of the 530 deg. C phase transition in LaBGeO5

    High-resolution neutron powder diffractometry has been used to characterize the structural phase transition which occurs in LaBGeO5 at 530 deg. C. The change in lattice parameters of the trigonal unit cell as a function of temperature, observed in the range from ambient to 700 deg. C, shows that the transition from the polar space group P31 to the non-polar space group P3121 is associated with a collapse of the a-dimension, whereas the c-dimension and the cell volume increase monotonically with small changes of slope at the transition temperature. The structure of the lower-temperature phase, previously determined at ambient temperature by single-crystal x-ray diffraction, has been refined at 20, 500 and 525 deg. C and the structure of the higher-temperature phase determined from data taken at 535, 560 and 630 deg. C. The thermal evolution of the atomic coordinates shows that the deciding role in the transition is provided by a complex movement of the B-O tetrahedron, in which the main component is a rotation around the 31 axis. The transition is continuous and results from structural changes which are displacive but also show order-disorder character. This conclusion is in accordance with the known thermal, optical and dielectric properties of this new multifunction (laser, ferroelectric and non-linear optic) material. In the high-temperature modification, the dynamically disordered double helical chain of B-O tetrahedra has no polarity in the c-direction. This is the main structural reason for the absence of ferroelectric properties above 530 deg. C. The lower transition temperature of 140 deg. C in the related phase LaBSiO5 may be understood by comparing the structural aspects of its transition with those of LaBGeO5 using the Abrahams-Jamieson-Kurtz criteria. The effect of isomorphic substitution for Ge with the smaller Si atoms is equivalent to pressure being applied to the helical B chain and results in a chain which is more tilted in the silicate than in the

  17. Effects of salvia miltiorrhiza bge on myocardial fibrosis in hypertensive rats

    TANG Zhong-zhi; DING Shi-fang; TANG Ying


    Abstract Objective: To study the effects of Salvia Miltiorrhiza Bge (SMB) on myocardial fibrosis in hypertension in rats. Methods: Normal Wistar kyoto rats served as negative control (group A). The rats with hypertension were divided into 2 groups: the hypertension group (group B) which served as the positive control and the SMB-treated hypertension group (group C). The effects of SMB on the systolic pressure, the myocardial content of aldosterone (ALD) and nitric oxide (NO) and the activity of superoxide dismutase (SOD) in the myocardium were detected. Results: The systolic pressure of the rats of group C showed no marked change after the administration of SMB and showed no difference from that of the rats of group B. The content of collagen Ⅰ and Ⅲ of the left ventricle, the collagen Ⅰ/collagen Ⅲ ratio and the content.of ALD were lower in group C than in group B and higher in group C than in group A. The content of NO and the activity of SOD in the myocardium were higher in group C than in group B and lower in group C than in group A. Conclusion: It was concluded that SMB was able to prevent or reverse the progress of myocardial fibrosis resulting from hypertension. The mechanism of this effect of SMB might be due to the fact that SMB can decrease the collagen synthesis and ALD content and increase collagen decomposition, NO content and SOD activity in the myocardium.

  18. Antihyperglycemic and Antihyperlipidemic Effects of Fruit Aqueous Extract of Berberis integerrima Bge. in Streptozotocin-induced Diabetic Rats.

    Ashraf, Hossein; Heidari, Reza; Nejati, Vahid


    Use of medicinal plants for attenuation of hyperglycemia and restoration of lipids disorder to normal level is clinically very important. The aim of present study was to evaluate the effects of Berberis integerrima Bge. fruit aqueous extract (BIFAE) on blood glucose and lipid profile in streptozotocin (STZ) - induced diabetic rats. The STZ-induced diabetic rats were treated by fruit aqueous extract of Berberis integerrima Bge. at doses (250 and 500 mg/Kg bw) and glibenclamide (0.6 mg/Kg bw) for 42 days by gavage. Blood glucose levels and body weights of rats were measured on weeks 0, 2, 4 and 6. Total lipid levels were determined in normal and STZ-induced diabetic rats after administration of the BIFAE and glibenclamide for 42 days. STZ-induced diabetic rats showed a significant (P<0.001) increases in the levels of blood glucose, triglycerides (TG), total cholesterol (TC), low density lipoprotein LDL-cholesterol (LDL-C) while body weight and high density lipoprotein HDL-cholesterolan (HDL-C) were significantly(P<0.001) decreased compared to normal rats. Daily administration of BIFAE did not possess the hypoglycemic and hypolipidaemic activity in STZ- diabetic rats during 6-week treatment period. Results indicate the usage of BIFAE in traditional medicine for the treatment of diabetes may need more investigation. PMID:25587320

  19. Suppression of Cladding Mode Coupling by B/Ge Codoped Photosensitive Fiber With Photosensitive and Depressed Inner Cladding


    Excess loss on the short wavelength side of the Bragg resonant wavelength caused by cladding mode coupling limits wide use of grating in the fiber communication system, especially in densed wavelength division multiplexing (DWDM) system.A novel photosensitive fiber design that have depressed cladding and photosensitive inner cladding in the same fiber is proposed, which can suppress cladding mode coupling greatly.Using MCVD method B/Ge codoped fiber with depressed cladding was fabriceted out, which was also doped in boron and germanium and had the photosensitivity.Finally, the transmission spectrum of written grating in this fiber by phase mask method verified its larger photosensitivity and greatly suppression of cladding mode coupling.

  20. 氮离子注入对蒙古黄芪多倍体诱导的影响%Effect of N + Implantation on the Inducement of Polyploid Astragalus membranaceus (Fisch.) Bge.var.mongholicus (Bge.) Hsiao

    张利珍; 李前忠; 杨林源; 武成艳


    A new method of improving induction rate of polyploid through chemical induction combined with physical mutation were proposed by using the diploid Astragalus membranaceus ( Fisch. ) Bge. Var. Mongholicus (Bge. ) Hsiao seeds as the materials and N+ beam as the mutagenic agent. The results indicated that N + implantation showed significant biological effects. The effects of N + implantation combined with colchicine on inducing polyploidy of Astragalus were obvious, 44.4% doubling rate was obtained by being treated by the combination of N+ ion implantation dose 2.6 x 1016 N + /cm2 and colchicine concentration 100 mg · L-1 for 5 d. The best result of 46.2% was obtained by using the combination of N+ implantation dose 5.2 x 1016 N + /cm2 and colchicine concentration 100 mg · L-1 for 10 d. They were higher than the control group of maximum induction rate 13.9% of colchicine concentration 100 mg · L-l, treatment time 15 d. Cell chromosome identification results showed that the polyploid is tetraploid.%利用二倍体蒙古黄芪种子为材料,以低能氮离子束为诱变源,将化学诱导与物理诱变相结合,探索出一套高效的多倍体诱导新方法.研究结果表明:氮离子注入种子后表现出明显的生物学效应;氮离子注入与秋水仙素联合诱导黄芪多倍体的效果很明显.氮离子注入剂量为2.6×1016 N+/cm2,秋水仙素浓度为100 mg·L-1,培养5d诱导率最高为44.4%;氮离子注入剂量为5.2×1016 N+/cm2,秋水仙素浓度为150mg· L-1,培养10d的诱导率最高为46.2%;二者均高于对照组秋水仙素浓度为100mg·L-1培养15 d的最高诱导率13.9%.利用细胞染色体计数鉴定多倍体为四倍体.

  1. Determination of Tanshinone ⅡA in Salvia miltiorrhiza Bge. in different harvest time%不同采收期丹参中丹参酮ⅡA的含量测定

    赵群; 赵成


    Objective :To investigate the content of Tanshinone ⅡA in Salvia miltiorrhiza different harvest time. Methods The content of Tanshinone ⅡA in Salvia miltiorrhiza Bge .was determined and analysed in different harvest time. Result:There is significant difference among the contents of Tanshinone ⅡA in Salvia miltiorrhiza Bge .in different harvest time. Conclusion Harvest time is the crucial factor for quality of processing and producing Salvia miltiorrhiza Bge.%目的:考察不同采收期丹参中丹参酮ⅡA的含量.方法:采用高效液相色谱法(HPLC),对不同采收期丹参中丹参酮ⅡA含量进行测定、分析.结果:发现不同采收期丹参在丹参酮ⅡA含量方面有显著差异.结论:在丹参的加工生产中应注意不同的采收季节对其质量的影响.

  2. Studies on Flavonoids Extraction Process of Dracocephalum Integrifolium Bge.%全叶青兰中黄酮类化合物的提取工艺研究



    In the paper,after a full analysis of the various means of extraction,we use the most effective extraction and design method on flavonoids extraction of dracocephalum integrifolium bge.and establish a comprehensive comparative evaluation system for the Flavonoids extraction.For the Flavonoids extraction of dracocephalum integrifolium bge.use the ultrasonic extraction can be the highest efficiency extraction.The optimum conditions are: Ultrasound 30 min,ultrasonic wave power 100 W,powder size 60~80 head,ethanol consistence was 70 %,extraction temperature 55 ℃.The total extraction time 2 h,extract twice,the ratio of solid and Liquid was 1:20,now,the total Flavonoids contents of Dracocephalum integrifolium Bge.was 27.11 mg/g.After enrichment with different solvent extract a preliminary separation of the extract after the separation of the qualitative analysis of the results showed that n-butanol and ethanol extracts of the content of flavonoids higher on the whole of flavonoids Lan Ye more polar compounds to the main flavonoid glycosides,the aglycone form of flavonoids low.%文章在考察了多种溶剂提取方法的基础上,运用最为有效的提取、设计方法提取了全叶青兰的黄酮成分,并对黄酮类物质的提取方法建立了综合比较评价的体系。对于全叶青兰总黄酮的提取,采用超声提取法可以得到最高的提取效率,其最佳工艺条件为超声30 min,超声波功率100 W,粒度60~80目,乙醇浓度为70%,提取温度为55℃,总提取时间2 h,提取次数2次,料液比为1:20时,全叶青兰总黄酮含量为27.11 mg/g。浓缩后的提取物采用不同溶剂进行了初步的分离,对分离后的提取物所作的定性分析的结果表明,正丁醇和乙醇萃取液中的黄酮类化合物的含量较高,说明全叶青兰中的黄酮类化合物以极性较大黄酮苷类为主,苷元形式存在的黄酮类含量较低。

  3. 不同炮制方法对丹参多糖含量的影响%Effects of Different Processes on Polysaccharide Content in Salvia Miltiorrhiza bge

    李炯; 袁胜浩; 马朝晖


    Objective: To study the content of polysaccharide in Salvia miltiorrhiza bge processed by different methods. Method: The sample was extracted by water and purified preliminarily by alcohol precipitation. The polysaccharide content was determined by phenol sulfuric acid method at UV wavelength of 490 nm. Result: The polysaccharide content in crude salvia miltiorrhiza, liquor salvia miltiorrhiza, vinegar salvia miltiorrhiza, rice stir-frying salvia miltiorrhiza and salvia miltiorrhiza charcoal was 3.08%, 4.63%, 4. 25% , 3. 89% and 1. 14% , respectively. Conclusion: The method is simple, convenient and accurate, and can be used in the de-termination of polysaccharide in Salvia miltiorrhiza bge. The polysaccharide contents in liquor salvia miltiorrhiza, vinegar salvia miltior-rhiza and rice stir-frying salvia miltiorrhiza are higher than that in crude salvia miltiorrhiza.%目的:比较丹参不同炮制品中多糖的含量.方法:多糖采用传统的水提醇沉法提取,多糖的含量用苯酚-硫酸法进行测定,以葡萄糖为对照品,检测波长490 nm.结果:生丹参、酒丹参、醋丹参、米炒丹参和丹参炭的多糖含量分别为3.08%、4.63%、4.25%、3.89%和1.14%.结论:建立的多糖含量测定方法操作简便,精密度高,数据稳定性好,重复性好,适用于丹参及其炮制品多糖含量的测定.不同炮制方法对丹参饮片中多糖的含量有不同程度的影响,酒蒸、醋制和米炒均显著提高了丹参饮片中多糖的含量.

  4. Effect of Salvia Miltiorrhiza Bge on Left Ventricular Hypertrophy and the Expression of Tumor Necrosis Factor-α in Spontaneously Hypertensive Rats

    SUN Lianping; ZHENG Zhi


    The effects of salvia miltiorrhiza Bge (SMB) on left ventricular hypertrophy (LVH) and the expression of tumor necrosis factor-α (TNF-α) in the left ventricle of spontaneously hypertensive rats and the action mechanism were investigated. Normal Wistar-kyoto (WKY) rats were used as negative control, and spontaneously hypertensive rats (SHR) were randomly assigned to receive placebo or SMB. SMB (1 g/kg·d) was injected intraperitoneally for 12 weeks. Systolic blood pressure (SBP) and left ventricular mass index (LVMI) were measured. HE, VG and immunohistochemical staining combined with computed morphometry were employed to evaluate the cardiomyocyte size,diameter, the collagen volume fraction (CVF), perivascular circumferential area (PVCA), and tumor necrosis factor-α (TNF-α) expression in the left ventricular tissue. The results showed, as compared with WKY rats, the SBP, LVMI, cardiomyocyte size, diameter, CVF, PCVA, and TNF-α expression were increased markedly in the 20-week-old spontaneously hypertensive rats. SMB decreased LVMI (P<0.01), size of cardiomyocytes (P<0.01), collagen volume fraction (P<0.01), perivascular circumferential area (P<0.01), and TNF-α expression (P<0.01), but had no effect on SBP (P>0.05). It was suggested that chronic administration of SMB could inhibit and reverse the development of LVH in spontaneously hypertensive rats independent of BP. TNF-α may be involved in the reversal mechanism of LVH by SMB.

  5. 抑制多重耐药致病菌的丹参内生真菌的筛选、鉴定及次生代谢产物分析%Isolation, identification and analysis of secondary metabolites of multidrug-resistance inhibiting endophytic fungi of Salvia miltiorrhiza Bge

    桑小雪; 郭静; 白林含


    This research aimed to study the antibacterial activity of endophytic fungi isolated from Salvia miltiorrhiza Bge in order to find a new type of antimicrobial substances.One hundred and forty five endophytic fungi were isolated and purified from the stems and leaves of Salvia miltiorrhiza Bge.Three strains with good antibacterial effects were obtained through antibacterial experiments on common poultry pathogens (Salmonella enteritidis,Salmonella pullorum,Pseudomonas aeruginosa,Staphylococcus aureus ATCC 29213,Escherichia coli O157∶H7 and Salmonella typhimurium) and multidrug resistant pathogens (the resistant strain of Salmonella,Staphylococcus aureus and Escherichia coli).At last,a strain S4 with the best antibacterial effects was obtained and identified as Phomopsis morphological observation and 18S rDNA sequence analysis methods.The follow-up experiment included preliminary analysis of the major categories of the chemical composition,LC-MS and GC-MS of the fermentation broth of the S4 strain.The results showed that the fermentation broth contains phenolic compounds,alkaloids and tyrosol with important biological activities.The results provide new resources for control of drug-resistance.%对四川道地药材丹参内生真菌的抑菌活性及其次生代谢产物进行研究,以期寻找出抑制多重耐药致病菌的新型抗菌物质.通过分离纯化丹参茎和叶中的内生真菌,得到145株菌株,将菌株发酵液分别进行普通致病菌(肠炎沙门氏菌、鸡白痢沙门氏菌、绿脓杆菌、金黄色葡萄球菌、大肠杆菌O157∶H7和鼠伤寒沙门氏菌)和多重耐药致病菌(沙门氏菌耐药株、金黄色葡萄球菌耐药株和大肠杆菌耐药株)的抑菌试验,筛选得到3株具有显著抑菌效果的菌株.其中抑菌效果最显著的一株菌株S4,经形态学观察和18S rDNA序列分析确定其为Phomopsis sp.对S4发酵液的乙酸乙酯萃取相进行大类成分、LC-MS和GC-MS分析,结果显示发

  6. Ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. root.

    Wang, Zhibing; Cao, Bocheng; Yu, Aimin; Zhang, Hanqi; Qiu, Fangping


    The ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction has been developed and applied to the extraction of four tanshinones, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone IIA in Salvia miltiorrhiza Bge. root. High performance liquid chromatography was applied to the separation and determination of the analytes. The ionic liquid was used as extraction solvent and target analytes were extracted with help of ultrasound. Then, ion-pairing agent was added into the sample solution, which resulted in the formation of water-insoluble ionic liquid in the solution. The phase separation was performed by centrifugation. The extraction, concentration and purification of target analytes were performed simultaneously. The experimental parameters, including type and volume of ionic liquid, sample amount, the size of sample particle, pH value of extraction medium, extraction temperature, extraction time, amount of ion-pairing agent and centrifuging time, were investigated and optimized. The calibration curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of 0.052-0.093 and 0.17-0.31 μg mL(-1), respectively. The recoveries were between 70.45% and 94.23% with relative standard deviations lower than 5.31%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with UAE and HRE. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods. PMID:25497891

  7. Megasporogenesis and Female Gametophyte Development in Salvia miltiorrhiza Bge%丹参大孢子发生和雌配子体发育

    武玉侠; 曹玉芳


    利用石蜡切片法对丹参不同时期花器官进行了解剖学研究.结果表明:丹参单珠被,薄珠心,倒生胚珠,有承珠盘结构.孢原细胞位于珠心一层表皮下,直接行使大孢子母细胞功能.大孢子母细胞减数分裂合点端或合点端第二个大孢子为功能大孢子,胚囊发育为蓼型.胚囊中卵细胞存在极性.助细胞在卵细胞产生极性分化前解体,即助细胞寿命较短.反足细胞在成熟胚囊中退化.极核在受精前融合,核中出现多个小核仁.%Using paraffin method to conduct the anatomical floral organ of Salvia miltiorrhiza Bge in different periods , the results show that in S. Miltiorrhiza the ovary is anatropous, single integument, thin nucellus and has hypos tase. The archesporial cell under one layer of the nucellar cell, directly functions as megaspore mother cell. Megaspore mother cells undergoes meiosis and the chalazal end megaspore or the second megaspore near the chala-zal end functions, the development of the embryo sac is polygonum type. The egg cell in the embryo sac existing polarity, the synergid cell egg cell degradation before the egg cell possess polarity, means the synergid cells possess a short life. Antipodal cells degradation in mature embryo sac. Polar nuclei fusion before fertilization and a numerous small nucleoli appeared.

  8. Comparation on Photosynthetic Characteristics of Ampelopsis humulifolia ‘Dong Yue Hong’and Ampelopsis humulifolia Bge%东岳红和葎叶蛇葡萄光合特性的比较

    方晓晓; 荀守华; 孙居文; 臧德奎; 王玉丽


    东岳红是叶蛇葡萄的一个红叶自然变异种,具有幼叶、嫩枝、卷须和花序均为紫红色及适应性强、易繁殖的特点,其选育填补了彩叶木质藤本观赏植物的空白,观赏利用前景良好。5月份是东岳红观赏性最佳的时期,为明确该时期其光合特征及与叶蛇葡萄的差异,在相同环境条件下测定分析了两者叶片的光合特性和色素含量。结果表明:两品种的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间 CO2浓度(Ci)的日变化趋势相近,无显著差异;Pn 的日变化呈双峰曲线,峰值出现在9∶00左右,15∶00左右又会出现一个小的峰值;Tr 日变化呈单峰曲线,峰值出现在13∶00左右;Gs 均呈降低趋势;Ci 为7∶00和17∶00值较高,9∶00和15∶00较低,11∶00~13∶00又有小幅回升。对光响应曲线和 CO2响应曲线的分析结果显示,两品种的光饱和点均在1600μmol·m -2·s -1左右,光补偿点均在30μmol·m -2·s -1左右,CO2饱和点均在1500μmol·m -2·s -1左右,东岳红的 CO2补偿点略高于叶蛇葡萄。同一时期相同叶位叶片中的叶绿素、类胡萝卜素、花色素苷含量,东岳红均显著高于叶蛇葡萄。%Ampelopsis humulifolia ‘Dong Yue Hong’is one variety of Ampelopsis humulifolia Bge.with red leaves,twiggery,tendril and inflorescence,and has strong adapatability for easy propagation.It fills in the blank of woody climber ornamental plant with color leaves,so it has better prospect for ornamental use.‘Dong Yue Hong’has the optimum ornamental value in May.To make clear its photosynthetic characteristics and the differences with Ampelopsis humulifolia this stage,their photosynthetic characters and pigment contents were determined and analyzed in the same conditions.The results showed that the diurnal variation of photosynthesis (Pn),transpiration rate (Tr

  9. Isolation and characterization of Bacillus subtilis EB-28, an endophytic bacterium strain displaying biocontrol activity against Botrytis cinerea Pers

    Shutong WANG; Tongle HU; Yanling JIAO; Jianjian WEI; Keqiang CAO


    The fungal pathogen Botrytis cinerea Pers. causes severe rotting on tomato fruits during storage and shelf life. As a biological control agent, endophytic bacterium was regarded as an effective alternative to chemical control. Out of 238 endophytic bacterial isolates, three strains (EB-15, EB-28, and EB-122) isolated from Lycopersicum esculentum Mill., Speranskia tuberculata (Bge.) Baill, and Dictamnus dasycarpus Turcz. respectively were found to be strongly antagonistic to the pathogen in vitro and were selected for further in vivo tests. One endophytic bacterium strain, encoded EB-28, was selected from the three in vivo tested isolates. The inhibitive rate of EB-28 reached 71.1% in vitro and 52.4% in vivo. EB-28 was identified as Bacillus subtilis according to its morphological, physiological, and biochemical characteristics and 16S rDNA sequence analysis.

  10. Pharmacological study on chemical composition and clinical application of Salvia miltiorrhiza and Salvia miltiorrhiza bge.f.alba leaf%丹参和白花丹参叶的化学成分药理研究及临床应用



    目的:探讨丹参和白花丹参叶的化学成分药理研究及临床应用,为新药的研制奠定基础。方法:通过参阅大量相关文献,对丹参和白花丹参叶的化学成分、药理研究及临床应用进行分析总结。结果:丹参和白花丹参叶所具有的抗氧化作用均能较好的预防脑梗塞,与根相比叶对脑缺血的保护作用更强,在对心脑血管疾病的防预治疗中被广泛应用;白花丹参叶中的水提物对糖尿病代谢紊乱症状的改善能够起到长期稳定的效果;另外丹参叶在治疗扁平疣、冠心病心绞痛等方面也具有较好的效果。结论:丹参和白花丹参叶均具有稳定的药理作用,但目前在抗氧化和保护脑梗塞的药理研究中仍以白花丹参叶为主,对于丹参叶的药理研究和临床应用则很少。因此对丹参叶主要化学成分进行深入的药理研究是很有必要的。%Objective:To study the pharmacological effects of chemical composition and clinical application of Salvia miltiorrhiza and Salvia miltiorrhiza bge.f.alba leaf, lay the foundation for the development of new drugs. Method: by referring to a large number of relevant literature, chemical constituents,pharmacological study and clinical application of Salvia miltiorrhiza and Salvia miltiorrhiza bge.f.alba leaf were analyzed. Results:the antioxidant effects of Salvia miltiorrhiza and Salvia miltiorrhiza bge.f.alba leaf has can prevent cerebral infarction better, compared with a protective effect on cerebral ischemia of the leaf is stronger, is widely used in the treatment ofcardiovascular and cerebrovascular disease prevention; Salvia miltiorrhiza bge.f.alba leaf water extract on diabetic metabolic disorder symptoms can playthe long-term stability of the effect of Salvia miltiorrhiza Bunge;in addition alsohas a good effect on the treatment of flat wart, such as coronary heart disease and angina. Conclusion: Salvia miltiorrhiza and Salvia

  11. 苦碟子化学成分的分离与鉴定%Isolation and identification of the constituents from whole plant of Ixeris sonchifolia( Bge.)Hance

    侯晶; 艾瑞婷; 周凌艳; 刘冰洁; 李玲芝; 彭缨


    目的 对菊科苦荬菜属植物抱茎苦荬菜[ Ixeris sonchifolia( Bge.) Hance]的化学成分进行研究.方法 运用硅胶、聚酰胺柱色谱、Sephadex LH-20柱色谱、ODS柱色谱、制备HPLC等分离手段进行化学成分的分离纯化,根据理化性质及波谱数据鉴定其结构.结果 从苦碟子全草中分离得到4个化合物.分别鉴定为3β-hydroxyolean-12-en-11-one acetate(1)、3,4-dihydroxybenzalacetone(2)、7-O-β-D-glucopyranosyl-luteolin-3’ -O-β-D-glucopyranoside(3)、5,7-dihydroxy-4’-methoxyflavone-7-rutinoside (4).结论 这些化合物均为首次从该属植物中分离得到.%Objective To synthesize flavone and its derivatives and study their antitumor activities. To find a new method for efficient synthesis of flavones. Methods The 1,3-dione compounds were synthesized from 2,4,6-trihydroxylacetophenohe via selective methylation,esterification,Baker-Venkataraman rearrangement, a series of flavones were obtained by trimethylsilyl trifluoromethanesulfonate(TMSOTf) catalytic cycliza-tion. Starting from chrysin as the lead compounds, six chrysin derivatives, including one new compound, were synthesized via alkylation reaction. In addition, six Mannich base derivatives of chrysin were synthesized through Mannich reaction from secondary amine and chrysin. Their in vitro antitumor activities were e-valuated in C6 cells and HepG2 cells by Mil assay. Results and Conclusions Seventeen compounds were synthesized and characterized by 'H-NMR, ES-MS. Preliminary pharmacological results showed that four compounds possessed more potent antitumor activity than chrysin in vitro.

  12. Relation of bud dormancy to carbohydrate metabolism in Cerasus humilis (Bge.) Sok.%休眠期欧李碳水化合物代谢与休眠关系的分析

    李秀珍; 陈苏丹; 李天忠


    This paper is concerned on the relation of bud dormancy to carbohydrate metabolism, The annual shoots from underground stem was used as the experimental materials. The components of carbohydrates and the enzymes activities were measured in phloem and bud of dormant Cerasus humilis (Bge.) Sok. The results indicated that soluble sugar content was higher than starch in phloem and bud in dormancy period. The highest ratio of soluble sugar and starch reached to 4.77. Most sugar was sucrose and then fructose, sorbitol and glucose. A few amount of fructose in bud were detected in natural dormancy stage. But its content increased rapidly in enhanced dormancy stage and in germination period,reaching to 2.05% in germination period. The changes in enzyme activities in phloem and bud were in line with that of soluble sugar. The activity of SPS was higher than that of other enzymes, but quickly decreased in natural dormancy stage,and reached to minimum at the end of the natural dormancy. The reduction in bud and phloem was 94. 18% and 84.78% respectively. The activity of p-amylase was higher that of a-amylase. Based on the integrated analyses above,the main accumulated carbohydrate in dormant Chinese dwarf cherry was soluble sugar. The relief of natural dormancy was obviously linked with the change of sucrose and reduction of the SPS activity. Change in the fructose contents was related to the dormancy and germination of bud.%为探讨休眠期欧李碳水化合物代谢与休眠的关系,以休眠期欧李1年生基生枝为试材,采用气相色谱等方法,分析了韧皮部、芽中碳水化合物含量及其相关酶活性变化。结果表明:休眠阶段欧李韧皮部和芽中可溶性糖含量均高于淀粉,二者比值最高可达4.77,其中含量最高的为蔗糖,其次是果糖、山梨醇和葡萄糖;自然休眠期芽中检查不到果糖含量,但在被迫休眠期和芽萌动期迅速增加,至芽萌动期质量分数达2.05%;休眠期韧皮部和芽中

  13. 响应面法优化丹参中抗无乳链球菌活性成分的提取工艺%Optimization of the Extraction Conditions of Active Components for Inhibition of Streptococcus agalactiae from Salvia miltiorrhiza Bge. Using Response Surface Methodology

    邓恒为; 郭伟良; 孙晓飞; 谢珍玉; 王世锋; 胡文婷; 周永灿


    In recent yearsStreptococcus agalactiae(SA) has become the most harmful pathogen to cultured tilapia in Hainan and many southern provinces of China.Salvia miltiorrhizaBge is highly resistant to SA, but it contains complex components and which component is responsible for the resistance to SA has not been reported. Here we investigated the effects of extraction conditions on the yield of anti-SA components inS. miltiorrhizaBge and optimized the extraction method. We first developed the agar diffusion method for the quantitative analysis of extracted anti-SA components; then we used the yields of anti-SA components fromSalvia miltiorrhizaBge as the responsive values to study the effects of extraction conditions on the yield of the anti-SA components, including the extraction solvent, extraction times, the ratio of liquid to solid, infiltration time, temperature and extraction time in single-factor experiments; finally we further optimized the ratio of liquid to solid, infiltration time, temperature and extraction time using the four-factor-three-level Box-Behnken experimental design with response surface method. The results of the agar diffusion showed that the standard equation for the determination of anti-SA components fromS. miltiorrhizaBge wasY= 4.842X+ 16.707 (R2= 0.9873). The results of the single-factor experiments showed that the most suitable extraction solvent and times was 20% ethanol aqueous solution for 1 time. The results of the Box-Behnken experimental design with response surface method showed that the infiltration time, the extraction temperature, and the ratio of liquid to solid had extremely vital effects on the responsive values. The optimum extraction conditions were as follows: the ratio of liquid to solid was 37.8:1.0 (ml:g), the infiltration time was 104 min, the extraction temperature was 86.7℃ and the extraction time was 182 min. The predicted maximum yield of anti-SA components was 25.95%, under the RSM model-generated optimal extraction

  14. Geobacteraceae strains and methods

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana


    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  15. Muscle strain (image)

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  16. Muscle strain treatment

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  17. Program Calibrates Strain Gauges

    Okazaki, Gary D.


    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

  18. Strains and Sprains

    ... ON THIS TOPIC Sports Medicine Center Preventing Children's Sports Injuries Computer-Related Repetitive Stress Injuries Knee Injuries Broken ... Knee Injuries Sports and Exercise Safety Dealing With Sports Injuries Groin Strain Ankle Sprains Strains and Sprains Stretching ...

  19. Strained Silicon Photonics

    Wehrspohn, Ralf B; Jörg Schilling; Christian Bohley; Clemens Schriever


    A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is inves...

  20. Evolutionary genomics and functional studies on the metabolic role of Blattabacterium, primary endosymbiont of cockroaches

    Patiño Navarrete, Rafael


    Introducció La simbiosi, entesa com la relació de interdependència entre dos o més individus de diferents espècies, ha tingut un profunda influència al llarg de l’evolució de la vida. De fet, hi ha un ampli consens respecte a la importància de les associacions simbiòtiques, en l’aparició i evolució primerenca de la cèl•lula eucariota, així com en l’evolució del sistema immunitari en eucariotes complexos o en l’adquisició de noves capacitats metabòliques en plantes i animals, permetent-los...

  1. Comparative Genomics of Blattabacterium cuenoti: The Frozen Legacy of an Ancient Endosymbiont Genome

    Patiño-Navarrete, Rafael; Moya, Andrés; Latorre, Amparo; Peretó, Juli


    Many insect species have established long-term symbiotic relationships with intracellular bacteria. Symbiosis with bacteria has provided insects with novel ecological capabilities, which have allowed them colonize previously unexplored niches. Despite its importance to the understanding of the emergence of biological complexity, the evolution of symbiotic relationships remains hitherto a mystery in evolutionary biology. In this study, we contribute to the investigation of the evolutionary lea...

  2. Diffraction tomography of strain

    Lionheart, W R B; Withers, P. J.


    We consider whether it is possible to recover the three dimensional strain field tomographically from neutron and x-ray diffraction data for polycrystalline materials. We show that the distribution of strain transverse to a ray cannot be deduced from one diffraction pattern accumulated along that path, but that a certain moment of that data corresponds to the transverse ray transform of the strain tensor and so may be recovered by inverting that transform given sufficient data. We show that t...

  3. Strained Silicon Photonics

    Ralf B. Wehrspohn


    Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

  4. Strain-engineered MOSFETs

    Maiti, CK


    Currently strain engineering is the main technique used to enhance the performance of advanced silicon-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Written from an engineering application standpoint, Strain-Engineered MOSFETs introduces promising strain techniques to fabricate strain-engineered MOSFETs and to methods to assess the applications of these techniques. The book provides the background and physical insight needed to understand new and future developments in the modeling and design of n- and p-MOSFETs at nanoscale. This book focuses on recent developments in st

  5. Highly Strained Organophosphorus Compounds

    Slootweg, J.C.


    In our research on small, strained organophosphorus ring systems we became interested in the synthesis and applications of species that are even more strained than the parent phosphirane, by introducing an exocyclic double bond (methylenephosphirane), and by cyclopropyl spirofusion to the edge (e.g

  6. Sprains and Strains

    ... people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can ... Trials and You was designed to help people learn more about clinical trials, why they matter, and ...

  7. The strained state cosmology

    Tartaglia, Angelo


    Starting from some relevant facts concerning the behaviour of the universe over large scale and time span, the analogy between the geometric approach of General Relativ- ity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time repro- duces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theor...

  8. An Ultrasonic Strain Gauge

    Kersemans, Mathias; Allaer, Klaas; Degrieck, Joris; Van Den Abeele, Koen; Pyl, Lincy; Zastavnik, Filip; Sol, Hugo; Van Paegem, Wim


    A method is introduced for the measurements of strain exploiting the interaction between ultrasound waves and characteristics of the insonified specimen. First, the response of obliquely incident harmonic waves to a deterministic surface roughness is utilized. Analysis of backscattered amplitudes in Bragg diffraction geometry then yields a measure for the in-plane strain field by mapping any shift in angular dependency. Secondly, the analysis of the reflection characteristics of normal incide...

  9. MEMS Graphene Strain Sensor

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  10. Longitudinal misalignment based strain sensor

    Andrews, Jeffrey Pratt


    A practical fiber optic strain sensor has been developed to measure strains in the range of 0.0 to 2.0 percent strain with a resolution ranging between 10 and 100 microstrain depending on sensor design choices. This intensity based sensor measures strain by monitoring strain induced longitudinal misalignment in a novel fiber interconnection. This interconnection is created by aligning fibers within a segment of hollow core fiber. Related splice loss mechanisms are investigated ...

  11. ConStrains identifies microbial strains in metagenomic datasets.

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk


    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived datasets provides insights into microbial community dynamics. PMID:26344404

  12. The strained state cosmology

    Tartaglia, Angelo


    Starting from some relevant facts concerning the behavior of the universe over large scale and time span, the analogy between the geometric approach of General Relativity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time reproduces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theories. The possible role of structure topological defects is also mentioned. The conclusion is that SSC is at least as good as the ΛCDM standard cosmology, giving a more intuitive interpretation of the physical nature of the phenomena.

  13. Novel strained superjunction VDMOS

    Naugarhiya, Alok; Dubey, Shashank; Kondekar, Pravin N.


    In this paper, we have proposed novel strained superjunction (s-SJ) vertical double diffused MOS (VDMOS). Through channel engineering, we have introduced strain effects in s-SJ device using thin separate p-type silicon-germanium (p-SiGe) layer over silicon p-pillar. Further, we have designed process flow for the possible fabrication of s-SJ VDMOS. The proposed s-SJ devices fitted with less input capacitance (Cin) and 1.2∼3 times higher output current density than conventional SJ VDMOS. Therefore, 40% less gate charge (Qg) is required to turn-on the s-SJ VDMOS and Ron A is optimized in between 12% and 46%.

  14. Strains in general relativity

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a 'fiducial observer'. We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations

  15. Strains in General Relativity

    Bini, Donato; Geralico, Andrea


    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a "fiducial observer." We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations.

  16. Geodetic surveying of strains

    Meixner, H.


    This article evaluates methods and apparatus used in the German Democratic Republic to assess vertical and horizontal deformations and strains caused by coal mining and mining of other deposits. Each of the methods is characterized; type of measuring apparatus and its accuracy is given. The following conventional methods of surveying are characterized: (I.) vertical strains: measurement with hydrostatic tube balance (apparatus produced by the Praezisionsmechanik Freiberg, with accuracy of 0.01 mm), trigonometric levelling (error up to 10 mm), geometric levelling (NI 007 and NI 008 apparatus produced by Carl Zeiss JENA), and direct height measuring; (II.) horizontal strains: direct surveying with accuracy higher than 5 mm/50 m, indirect surveying (theodolite THEO 010 A produced by the Carl Zeiss JENA), and alignment method (using apparatus produced by Praezisionsmechanik, Freiberg). Advanced surveying methods are also discussed: electro-optical method (using EOK 2000 range finder produced by Carl Zeiss JENA, with average error ranging from 5 mm to 10 mm), laser method (LF-1 and LFG-1 lasers produced by Carl Zeiss JENA), measuring gyroscope used to measure contorsion (MRK 2 gyroscope produced by the Praezisionsmechanik, Freiberg); photogrammetry: stereophotogrammetry and so-called parallel photogrammetry. (15 refs.) (In Polish)

  17. Temperature controlled strain gaged extensometer

    Ramos, G. L.; Seplow, S.


    Temperature controlled strain-gaged extensometer measures longitudinal and girth deflections of pressure vessels in excess of one percent strain during pressurization and depressurization with cryogenic fluids at cryogenic temperatures. The device is of beryllium-copper strips.

  18. MEMS Resonant Strain Sensor Integration

    Myers, David Richard


    Despite commercial availability since the 1950's, silicon strain sensors have not experienced the same success as other microdevices, such as accelerometers, pressure sensors, and inkjet heads. Strain sensors measure mechanical deformation and could be used in many structural components, improving safety, controls, and manufacturing tolerances. This thesis examines major strain sensing techniques and highlights both advantages and disadvantages of each. MEMS resonant strain gauges are iden...

  19. Strain calibration of optical FBG-based strain sensors

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf


    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  20. Precision determination of strains by strain measurement method

    Method for precision strain measurement determination of strains measurement determination of strains by direct measurement of the resistance of strain gauge resistors put on the sample, by constant current bridge MOD-61 of 0.05 class using a zero method by single bridge double-clamp circuit is described. Strain measurement technique was used to investigate residual stresses in tubular samples. Sample external diameter made up 30 mm, the length - 180, the wall thickness-11 mm. To evaluate the method sensitivity, annealed samples were investigated (annealing temperature-850-880 deg C, hold-up-2 h, cooling in the furnace). It is ascertained, that the method provides for 0.3-0.5 μm strain measurement accuracy even if sample strains do not exceed 3.0-3.6 μm and correspond to residual stress level of no more than 20 MPa

  1. Development of reversible strain gage

    A high-temperature strain gage which can be peeled after taking required apparent strain measurements in a furnace and can be attached reverse-side-up at the point of interest on a test structure was developed. Using the ''reversible'' strain gage with selected room-temperature curing type polyester adhesive, one can expect to measure thermal strain accurately, especially for on large structures, at the first test in temperature up to 250 deg C. The repeatability of apparent strains for about 100 reversible gages was within 50 microstrains of difference at 250 deg C (within 30 microstrains of difference for 80 % of the test gages). (author)

  2. [Echinococcus and strain concepts].

    Utük, Armağan Erdem; Simsek, Sami


    Hydatid disease (echinococcosis) is one of the most important parasitic zoonoses and remains a public health and economic problem all over the world. Echinococcus granulosus includes a number of genetic variants and, up to date, analyses of mitochondrial DNA sequences have identified ten distinct genetic types (genotypes G1-10). This categorization follows closely the pattern of strain variation emerging based on biological characteristics. The extensive variation in E. granulosus may influence life-cycle patterns, host specificity, development rate, antigenicity, transmission dynamics, sensitivity to chemotherapeutic agents, and pathology. In this review, the recent genetic characterizations of Echinococcus genus have been summarized. PMID:18351549

  3. Asymptomatic bacteriuria Escherichia coli strains

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per


    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast to...... uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...... against the UPEC strain CFT073 was also studied. The different ABU strains displayed a wide variety of the measured characteristics. Half of the ABU strains displayed functional type 1 fimbriae while only one expressed functional P fimbriae. A good correlation between the growth rate of a particular...

  4. Reconstruction of axisymmetric strain distributions via neutron strain tomography

    Predicting the behaviour of structural components under a particular set of loading conditions requires knowledge of the residual elastic strain distribution throughout the bulk of these components. Characterising the 3D strain state at any particular point involves the measurement of six independent components which make up the second order strain tensor. Mapping the complete strain distribution throughout large volumes thus presents significant practical challenges. One possible solution to this problem is to reconstruct the 3D variation of strain components using tomographic techniques. The basic principle underpinning this idea is that the multi-component strain tensor can be reconstructed from a redundant set of lower order projection data. Here we demonstrate this fundamental concept for two samples: a shrink fit ‘ring-and-plug’ sample, and a spray-quenched circular cylinder, both possessing axially symmetric internal strain distribution. We present and contrast different approaches to the strain tomography problem. The methods described here can also be readily applied to high-energy X-ray diffraction measurements and represent an important step toward developing the tomographic reconstruction framework for strain tensor distributions of arbitrary complexity. The major benefit of neutron strain tomography is that the incident beam flux is utilised more fully, greatly reducing the data collection times. Using micro-channel plate (MCP) neutron detectors, a spatial resolution of the order of 0.1 mm can be achieved .

  5. Strain in silicon nanowire beams

    Ureña, Ferran; Olsen, Sarah H.; Šiller, Lidija; Bhaskar, Umesh; Pardoen, Thomas; Raskin, Jean-Pierre


    In this work, strain in silicon free standing beams loaded in uniaxial tension is experimentally and theoretically investigated for strain values ranging from 0 to 3.6%. The fabrication method allows multiple geometries (and thus strain values) to be processed simultaneously on the same wafer while being studied independently. An excellent agreement of strain determined by two non-destructive characterization techniques, Raman spectroscopy and mechanical displacement using scanning electron microscopy (SEM) markers, is found for all the sample lengths and widths. The measured data also show good agreement with theoretical predictions of strain based upon continuum mechanical considerations, giving validity to both measurement techniques for the entire range of strain values. The dependence of Young's modulus and fracture strain on size has also been analyzed. The Young's modulus is determined using SEM and compared with that obtained by resonance-based methods. Both methods produced a Young's modulus value close to that of bulk silicon with values obtained by resonance-based methods being slightly lower. Fracture strain is analyzed in 40 sets of samples with different beam geometries, yielding values up to 3.6%. The increase in fracture strain with decreasing beam width is compared with previous reports. Finally, the role of the surface on the mechanical properties is analyzed using UV and visible lasers having different penetration depths in silicon. The observed dependence of Raman shift on laser wavelength is used to assess the thermal conductivity of deformed silicon.

  6. Asymptomatic bacteriuria Escherichia coli strains

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per


    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast to...... uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...

  7. Hydrogen production from microbial strains

    Harwood, Caroline S; Rey, Federico E


    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  8. Will the swine strain crowd out the seasonal influenza strain?

    Schinazi, Rinaldo B


    We use spatial and non spatial models to argue that competition alone may explain why two influenza strains do not usually coexist. The more virulent strain is likely to crowd out the less virulent one. This can be seen as a consequence of the Exclusion Principle of Ecology. We exhibit, however, a spatial model for which coexistence is possible.

  9. Tissue Velocity, Strain und Strain Rate bei Hunden mit Mitralklappenendokardiose

    Javornik, Ana


    In der vorliegenden Arbeit „Tissue Velocity, Strain und Strain Rate bei Hunden mit Mitralklappenendokardiose“ wurden erstmals die Geschwindigkeits- und Verformungsparameter zur Evaluierung von Hunden mit Mitralklappenendokardiose angewendet. Diese erweisen sich als neue und viel versprechende Möglichkeiten zur Quantifizierung der regionalen Myokardfunktion. Die myokardialen Funktionsparameter finden in der Humanmedizin weit verbreitete Anwendung und auch in der Tiermedizin erlangen sie zunehm...

  10. TL transgenic mouse strains

    As a result of abnormal development of the thymus of these mice, TCR αβ lineage of the T cell differentiation is disturbed and cells belonging to the TCR γδ CD4- CD8- double negative (DN) lineage become preponderant. The γδ DN cells migrate into peripheral lymphoid organs and constitute nearly 50% of peripheral T cells. Immune function of the transgenic mice is severely impaired, indicating that the γδ cells are incapable of participating in these reactions. Molecular and serological analyses of T-cell lymphomas reveal that they belong to the γδ lineage. Tg.Tlaa-3-1 mice should be useful in defining the role of TL in normal and abnormal T cell differentiation as well as in the development of T-cell lymphomas, and further they should facilitate studies on the differentiation and function of γδ T cells. We isolated T3b-TL gene from B6 mice and constructed a chimeric gene in which T3b-TL is driven by the promoter of H-2Kb. With the chimeric gene, two transgenic mouse strains, Tg. Con.3-1 and -2 have been derived in C3H background. Both strains express TL antigen in various tissues including skin. The skin graft of transgenic mice on C3H and (B6 X C3H)F1 mice were rejected. In the mice which rejected the grafts, CD8+TCRαβ cytotoxic T cells (CTL) against TL antigens were recognized. The recognition of TL by CTL did not require the antigen presentation by H-2 molecules. The results indicated that TL antigen in the skin becomes a transplantation antigen and behaves like a typical allogeneic MHC class I antigen. The facts that (B6 X C3H)F1 mice rejected the skin expressing T3b-TL antigen and induced CTL that killed TL+ lymphomas of B6 origin revealed that TL antigen encoded by T3b-TL is recognized as non-self in B6 mice. Experiments are now extended to analyze immune responses to TL antigen expressed on autochthonous T cell lymphomas. (J.P.N.)

  11. What Are Sprains and Strains?

    ... and Strains Find a Clinical Trial Journal Articles Sprains and Strains PDF Version Size: 119 KB Audio Version Time: 07: ... Twist a knee. Where Do Sprains Usually Occur? Sprains happen most often in the ankle. Sometimes when people fall and land on their ...

  12. Strain measurements at railway wheels

    The development of the radial strain component in railway wheels was investigated by neutron diffraction. In the as manufactured state four railway wheels were investigated. In all four wheels no significant strains were found. After 18,400 km usage first strain gradients close to the outer surface of the wheels were detected. In axial middle ranges the changes in strain are weak. After an usage of 61,000 km the gradients becomes strong at the axial outer position between about +700 με close below the tread and -500 με in a depth of 12.5 mm below the tread. At axial middle positions also strain gradients are formed. The end of live state (510,000 km) differs only slightly from the state measured after a usage of 61,000 km

  13. Pin clad strains in Phenix

    The Phenix reactor has operated for 4 years in a satisfactory manner. The first 2 sub-assembly loadings contained pins clad in solution treated 316. The principal pin strains are: diametral strain (swelling and irradiation creep), ovality and spiral bending of the pin (interaction of wire and pin cluster and wrapper). A pin cluster irradiated to a dose of 80 dpa F reached a pin diameter strain of 5%. This strain is principally due to swelling (low fission gas pressure). The principal parameters governing the swelling are instantaneous dose, time and temperature for a given type of pin cladding. Other types of steel are or will be irradiated in Phenix. In particular, cold-worked titanium stabilised 316 steel should contribute towards a reduction in the pin clad strains and increase the target burn-up in this reactor. (author)

  14. Recent advances in echocardiography: strain and strain rate imaging

    Mirea, Oana; Duchenne, Jurgen; Voigt, Jens-Uwe


    Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications.

  15. Isolation of Endophytic Fungi from Limonium bicolor (Bge.)Kuntze and Their Microbial Inhibition Activities%药用植物二色补血草内生真菌分离及其抑菌活性初步研究

    毕江涛; 潘润霞; 黄盼盼; 吕雯; 关晓庆


    The endophytic fungi were isolated from root,stem and leaf of the host by tissue inoculation culture and five pathogenic fungi and four bacteria strains used as targeting microbes to test microbial inhibition activity by agar plate antagonistic action and modified agar gel diffusion methods. The results indicated that: (1)Eighteen fungal endophytic strains were isolated from the host. Most of them came from leaf,then root and stem,and the isolated strains attribute to four genera,two families,and two orders based on morphological characteristics. (2)For the isolated strains,ten of them were found to have some microbial inhibition activities against two or more pathogenic fungi,making up 55. 6% of the total isolates,and eight isolated fungi strains showed inhibition activities against one or more bacteria, respectively, reaching up to 44. 4% of the total isolates in number. The strain LBEFL001 and LBEFL006 had evident antifungal activities against 5 pathogenic fungal strains. They ascribed to Aspergillus sp. and Penicilium sp. individually. The strain LBEFR006 and LBEFS002 showed evident antibacterial activities to Staphylococcus aureus and Pseudomonas aeruginosa , respectively. They both ascribed to Fusidium sp.. The strain LBEFL004 expressed evident antibacterial activities to Bacillus subtilis and S. aureus, belonging to Aspergillus sp. . It was found that the medicinal plant Limonium bicolor had relatively abundant fungal endophytic resource, and the isolatded endophytic fungi had evident inhibition activities against plant pathogens and showed relatively broad spectrum,and meanwhile the isolates as a whole had a certain of selectivity for bacterial inhibition, and inclined to be more antagonistic to S. aureus in general.%对药用植物二色补血草内生真菌进行分离,以番茄灰霉病菌、黄瓜枯萎病菌、枸杞黑果病菌、黄瓜立枯病菌、小麦全蚀病菌、枯草芽孢杆菌、大肠杆菌、金黄色葡萄球

  16. Magnetostriction strain measurement: heterodyne laser interferometry versus strain gauge technique

    Gorji Ghalamestani, Setareh; Vandevelde, Lieven; J.J. Dirckx, Joris; Melkebeek, Jan


    Deformation of the ferromagnetic material, known as magnetostriction, causes vibrations and noise of electrical machines and transformer cores. A setup by using heterodyne laser interferometers has been built to measure the magnetostriction strains as a function of the applied magnetic field. The measurement results on a sample of nonoriented electrical steel are presented in this work. These results are compared with those obtained by using a strain gauge setup. The laser measurements are l...

  17. Mercury retention in several strains and strain crosses of chickens

    Miller, V.L.; Bearse, G.E.; Csonka, E.


    The retention of mercury from injections of mercuric chloride was determined in 32 samples of chicks from various strains and strain crosses of egg type stock. The chicks retaining the most mercury had some four times as much mercury in the liver and kidneys as the chicks retaining the lowest amount. The chicks selected for resistance to leukosis retained more mercury than the susceptible chicks within several leukosis breeding programs.

  18. Low TCR nanocomposite strain gages

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)


    A high temperature thin film strain gage sensor capable of functioning at temperatures above C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  19. Roll bonding of strained aluminium

    Staun, Jakob M.


    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... circumstances both materials show good bonding, but the high purity material is excluded because of recrystallisation and the resulting loss of mechanical properties. The effect of cross stacking and roll bonding pre-strained sheets of the commercial purity material is investigated and some dependence of the...... cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  20. Covalent functionalization of strained graphene

    Boukhvalov, Danil W.; Son, Young-Woo


    Enhancement of the chemical activity of graphene is evidenced by first-principles modelling of chemisorption of the hydrogen, fluorine, oxygen and hydroxyl groups on strained graphene. For the case of negative strain or compression, chemisorption of the single hydrogen, fluorine or hydroxyl group is energetically more favourable than those of their pairs on different sublattices. This behaviour stabilizes the magnetism caused by the chemisorption being against its destruction by the pair form...

  1. Hypervirulent strains of Clostridium difficile

    Cookson, Barry


    North America has seen increasing numbers of hospitalised patients and others in nursing homes and the community, with more severe Clostridium difficile associated diarrhoea. This is also described in Northern Europe and surveillance systems are being developed or improved to monitor the situation. One strain (ribotype O27) is described in detail and, like other emerging strains, is demonstrating increasing antimicrobial resistance, notably to quinolone antibiotics. However, its association w...

  2. Biocontrol mechanisms of Thrichoderma strains

    Benítez Fernández, Concepción Tahía; Rincón Romero, Ana María; Limón Mirón, María del Carmen; Carballo Codón, Antonio


    The genus Trichoderma comprises a great number of fungal strains that act as biological control agents, the antagonistic properties of which are based on the activation of multiple mechanisms. Trichoderma strains exert biocontrol against fungal phytopathogens either indirectly, by competing for nutrients and space, modifying the environmental conditions, or promoting plant growth and plant defensive mechanisms and antibiosis, or directly, by mechanisms such as mycoparasitism. These indirect a...

  3. Strain evaluation in fatigue analysis

    Thermoplastic analysis and more precisely fatigue analysis of nuclear components working at high temperature is usually very difficult and very expensive. Simplified methods have been proposed and are generally used to perform analysis of these structures. These simplified methods require elastic analysis of the component. For a fatigue analysis it is necessary to obtain a very precise value of the strains so the elastic strains must be corrected in order to take plasticity into account. This later appears in two different ways. Non linearity of material which induces strain amplification when working in the plastic field especially near by geometric discontinuities. That can be taken into account with a coefficient Ke. Triaxiality and isovolumic character of strains in the plastic field. That also induces strain amplification with regard to elastic computation. It is proposed in this work to introduce a coefficient Kv to estimate this strain amplification. Several elastic and plastic calculations for typical geometries, have been done in order to test the importance of these parameters and to set up methods for evaluating the coefficients Ke and Kv

  4. Genome Sequence of Pseudomonas chlororaphis Strain 189

    Town, Jennifer; Audy, Patrice; Boyetchko, Susan M.


    Pseudomonas chlororaphis strain 189 is a potent inhibitor of the growth of the potato pathogen Phytophthora infestans. We determined the complete, finished sequence of the 6.8-Mbp genome of this strain, consisting of a single contiguous molecule. Strain 189 is closely related to previously sequenced strains of P. chlororaphis. PMID:27340063

  5. Strain Growth in Containment Vessels



    Strain growth is a phenomenon observed in containment vessels subjected to internal blast loading.The elastic response of the vessel may become larger in a later stage compared to its response during the initial stage.The dynamic responses of infinitely long cylindrical containment vessels subjected to uniformly-distributed internal blast loading are studied using LS-DYNA.The development of bending modes and the interaction between the breathing mode and bending modes are observed.The methodology developed for dynamic elastic buckling analysis is employed to study the strain growth phenomenon in explosion containment vessels.It is shown that the dynamic instable vibration of a containment vessel is the basic mechanism of strain growth.

  6. Thermoelectric properties of strained silicon

    Hinsche, Nicki F.; Zahn, Peter [Martin-Luther-Universitaet, Institut fuer Physik, Von-Seckendorff-Platz 1, 06120 Halle/S. (Germany); Mertig, Ingrid [Martin-Luther-Universitaet, Institut fuer Physik, Von-Seckendorff-Platz 1, 06120 Halle/S. (Germany); Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)


    Starting from bulk silicon, we study the change in thermoelectric properties due to symmetry breaking in rolled-up and layered Si which might lead to nanostructured thermoelectrics. Valley splitting in strained Si caused by tetragonal distortion was studied recently with respect to the enhancement of electron mobility. Our results show that the tetragonal distortion has a strong influence on the electronic transport properties. The electronic structure is calculated self consistently within the framework of density functional theory. The transport properties are studied in the diffusive limit applying the Boltzmann theory in relaxation time approximation. In detail, the anisotropy of the electrical conductivity, the thermopower and the resulting powerfactor in the in-plane and off-plane directions are studied in dependence on strain, doping level and temperature. It is shown, that the powerfactor at a given temperature can be enhanced slightly by strain for p-doping, while no enhancement is obtained for n-doping.

  7. Spin transport in graphene superlattice under strain

    Sattari, Farhad


    In this paper, the spin-dependent transport and the spin polarization properties for graphene superlattice with Rashba spin-orbit interaction (RSOI) in the presence of zigzag and armchair direction strain are studied. It is found that for the zigzag direction strain the angular range of the spin-inversion can be efficiently controlled by the strain strength. In addition, the efficiency of spin-inversion and spin-dependent conductivity decreases by increasing the strain strength. When the armchair direction strain is applied to a monolayer graphene superlattice the spin polarization can be observed and increases by increasing the strain strength, whereas for the zigzag direction strain it is zero.

  8. Myocardial Strain and Strain Rate Imaging: Comparison between Doppler Derived Strain Imaging and Speckle Tracking Echocardiography

    Anita Sadeghpour


    Full Text Available Regional myocardial function has been traditionally assessed by visual estimation (1. Echocardiographic strain imaging which is known as deformation imaging, has been emerged as a quantitative technique to accurately estimate regional myocardial function and contractility. Currently, strain imaging has been regarded as a research tool in the most echocardiography laboratories. However, in recent years, strain imaging has gain momentum in daily clinical practice (2. The following two techniques have dominated the research arena of echocardiography: (1 Doppler based tissue velocity measurements, frequently referred to tissue Doppler or myocardial Doppler, and (2 speckle tracking on the basis of displacement measurements (3. Over the past two decades, Tissue Doppler Imaging (TDI and Doppler –derived strain (S and strain rate (SR imaging were introduced to quantify regional myocardial function. However, Doppler–derived strain variables faced criticisms, with regard to the angle dependency, noise interference, and substantial intraobserver and interobserver variability. The angle dependency is the major weakness of Doppler based methodology; however, it has the advantage of online measurements of velocities and time intervals with excellent temporal resolution, which is essential for the assessment of ischemia (4. Speckle-tracking echocardiography (STE or Non Doppler 2D strain echocardiography is a relatively new, largely angle-independent technique that analyzes motion by tracking natural acoustic reflections and interference patterns within an ultrasonic window. The image-processing algorithm tracks elements with approximately 20 to 40 pixels containing stable patterns and are described as ‘‘speckles’’ or ‘‘fingerprints’’. The speckles seen in grayscale B-mode (2D images are tracked consecutively frame to frame (5, 6. Assessment of 2D strain by STE is a semiautomatic method that requires definition of the myocardium

  9. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.


    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  10. Computational Strain Gradient Crystal Plasticity

    Niordson, Christian Frithiof; Kysar, Jeffrey W.


    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...

  11. Job strain and alcohol intake

    Heikkilä, Katriina; Nyberg, Solja T; Fransson, Eleonor I;


    The relationship between work-related stress and alcohol intake is uncertain. In order to add to the thus far inconsistent evidence from relatively small studies, we conducted individual-participant meta-analyses of the association between work-related stress (operationalised as self-reported job...... strain) and alcohol intake....

  12. Trials with a Strain Gauge.

    Auty, Geoff


    Describes an attempt to match the goals of the practical demonstration of the use of a strain gauge and the technical applications of science and responding to student questions in early trials, while keeping within the level of electronics in advanced physics. (Author/JRH)

  13. Material mechanical characterization method for multiple strains and strain rates

    Erdmand, III, Donald L.; Kunc, Vlastimil; Simunovic, Srdjan; Wang, Yanli


    A specimen for measuring a material under multiple strains and strain rates. The specimen including a body having first and second ends and a gage region disposed between the first and second ends, wherein the body has a central, longitudinal axis passing through the first and second ends. The gage region includes a first gage section and a second gage section, wherein the first gage section defines a first cross-sectional area that is defined by a first plane that extends through the first gage section and is perpendicular to the central, longitudinal axis. The second gage section defines a second cross-sectional area that is defined by a second plane that extends through the second gage section and is perpendicular to the central, longitudinal axis and wherein the first cross-sectional area is different in size than the second cross-sectional area.

  14. Engineering piezoresistivity using biaxially strained silicon

    Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads;


    piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity to......We calculate the shear piezocoefficient of p-type silicon with grown-in biaxial strain using a 66 k·p method. We find a significant increase in the value of the shear piezocoefficient for compressive grown-in biaxial strain, while tensile strain decreases the piezocoefficient. The dependence of the...

  15. Plane strain test for metal sheet characterization

    Flores, Paulo; Bonnet, Félix; Habraken, Anne


    This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field distribution is measured over the whole deformable zone of a plane strain test specimen by an optical strain gauge. The chosen material is the DC06 IF steel of 0.8 mm thickness. The stress field is computed for several geometries at different strain levels by a Finite Element (FE) commer...

  16. Computational strain gradient crystal plasticity

    Niordson, Christian Frithiof; Kysar, Jeffrey W.


    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  17. Electronic Transport in Strained Graphene

    Aguilera, Juan Luis


    Graphene is a single atomic layer material with exceptional electronic and mechanical properties. Graphene has formed the basis of many nanoelectromechanical and strain sensing devices. However, the ultimate limit of miniaturization of such sensors has not yet been ascertained. In this work we present the fabrication and electrical characterization of nanoscale pressure sensors realized from suspended graphene membrane devices.We start in chapter 1 by describing the elemental electronic prope...

  18. Using Strain Analysis For Landslides

    Talich, Milan

    Vol. 4. Kyoto : International Consortium on Landslides (ICL), 2014, s. 178-184. [World Landslide Forum 3. Beijing (CN), 02.06.2014-06.06.2014] R&D Projects: GA MPO FR-TI4/436 Institutional support: RVO:67985556 Keywords : strain analysis * deformation analysis * displacement vectors * mechanics of continuum * landslides Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  19. Temperature-Compensating Inactive Strain Gauge

    Moore, Thomas C., Sr.


    Thermal contribution to output of active gauge canceled. High-temperature strain gauges include both active gauge wires sensing strains and inactive gauge wires providing compensation for thermal contributions to gauge readings. Inactive-gauge approach to temperature compensation applicable to commercially available resistance-type strain gauges operating at temperatures up to 700 degrees F and to developmental strain gauges operating at temperatures up to 2,000 degrees F.

  20. Strain Monitoring of Flexible Structures

    Litteken, Douglas A.


    , such as tensile testing, fatigue testing, and shear testing, but common measurement techniques cannot be used on fabric. Measuring strain in a material and during a test is a critical parameter for an engineer to monitor the structure during the test and correlate to an analytical model. The ability to measure strain in fabric structures is a challenge for NASA. Foil strain gauges, for example, are commonplace on metallic structures testing, but are extremely difficult to interface with a fabric substrate. New strain measuring techniques need to be developed for use with fabric structures. This paper investigates options for measuring strain in fabric structures for both ground testing and in-space structural health monitoring. It evaluates current commercially available options and outlines development work underway to build custom measurement solutions for NASA's fabric structures.

  1. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

    Dharanesh Gangaiah

    Full Text Available Although cutaneous ulcers (CU in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin?To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin.These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

  2. Lewis Strain Gauge Laboratory: Status and plans

    An in-house lab was established for developing, testing, and evaluating high-temperature strain gauges and to aid in in-house applications of high-temperature strain instrumentation. The lab is automated to provide computer control of oven temperatures, imposed strain, and data sampling

  3. Influence of particles on work hardening strain and recovery strain

    Blum, W.; Dvořák, Jiří; Král, Petr; Sklenička, Václav

    Brno: Ústav fyziky materiálů AV ČR, v. v. i., 2015 - (Dlouhý, A.; Kunz, L.). s. 137-137 ISBN 978-80-87434-07-9. [ICSMA-17 International Conference on the Strength of Materials /17./. 09.08.2015-14.08.2015, Brno] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : recovery strain * CuZr particles * crystallite boundaries * work hardening Subject RIV: JG - Metallurgy

  4. Sensibility of different wheat varieties (strains) to Ar+ implantation

    The sensibility of different wheat varieties (strains) to Ar+ implantation was studied. The results showed that the survival rate of 21 wheat varieties (strains) at the dose of 6 x 1016 Ar+/cm2 could be divided into five groups: surplus sensitive varieties (strains), sensitive varieties (strains), transitional varieties (strains), obtuse varieties (strains) and surplus obtuse varieties (strains). The sensibility of wheat varieties (strains) to Ar+ injection is high-moisture-fertility wheat varieties (strains) > medium-moisture-fertility wheat varieties (strains) > dry land wheat varieties (strains). The study has provided theoretical basis in induced mutation medial lethal dose of different wheat varieties (strains) to Ar+ implantation. (authors)

  5. Monoclonal antibodies to Toxoplasma gondii strain 119 identify recently isolated Danish strains as one group

    Jensen, L.; Petersen, E.; Henriksen, S.A.; Dietz, Hans-Henrik; Lind, Peter


    Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain restricted markers. Strain restriction extended beyond discrimination of the 119 and RH...

  6. Local strains in waste tank deflagration analysis

    In recent years extensive effort has been expended to qualify buried nuclear waste storage tanks under accident conditions. One of these conditions is deflagration of the combustible gases which may build up over time. While much work has been done to calculate the general strain state, less effort has been made to address the local strains at structural discontinuities. An analytical method is presented for calculating these local strains and combining them with the general strain state. A closed form solution of the local strains is compared to a finite element solution

  7. Spontaneous abortion and physical strain around implantation

    Hjollund, N H; Jensen, Tina Kold; Bonde, Jens Peter;


    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date of...

  8. Transient temperature response of strain gages

    When an electrical resistance strain gage bonded to a material is subjected to a temperature change, the resistance of the strain gage changes even though the material is free of stress. This temperature-induced resistance change is generally expressed in strain units and is commonly called apparent strain or thermal output. The thermal expansion coefficients and the temperature coefficient of resistance are temperature-dependent quantities and not necessarily linearly related to temperature. For transient temperature conditions, the two temperatures are different. The magnitude and effect of this temperature difference on apparent strain is studied

  9. Strain Engineering of Transition Metal Dichalcogenides

    Dadgar, Ali; Pasupathy, Abhay; Herman, Irving; Wang, Dennis; Kang, Kyungnam; Yang, Eui-Hyeok

    The application of strain to materials can cause changes to bandwidth, effective masses, degeneracies and even structural phases. In the case of the transition metal dichalcogenide (TMD) semiconductors, small strain (around 1 percent) is expected to change band gaps and mobilities, while larger strains are expected to cause phase changes from the triangular 2H phase to orthorhombic 1T' phases. We will describe experimental techniques to apply small and large (around 10 percent) strains to one or few layer samples of the TMD semiconductors, and describe the effect of the strain using optical (Raman, photoluminescence) and cryogenic transport techniques.

  10. Stress-strain properties of railway steel at strain rates of upto 105 per second

    This paper presents the stress-strain characteristics of railway steel at strain rates of up to 105/s at room temperature determined by a new technique. In determining the results, account has been taken of the strain-rate variation, the total strain and the strain rate history. The effect of friction, material inertia and temperature rise is also assessed and an empirical constitutive equation describing the strain-rate and strain sensitive flow stress for this type of steel is proposed. (orig.)

  11. Comparison between strain values of plates measured by ESPI technique and strain gauge method

    Comparison between strain values of plates measured by Electronic Speckle Pattern Interferometry(ESPI) method and strain gauge method is discussed. Unlike traditional method, such ax strain gauge and moire method, ESPI method requires no special surface preparations or attachments and can be measured in-plane displacement with non-contacting in real-time. In this study, specimens are loaded in parallel using tensile testing machine. In front of a specimen three strain gauges are bonded with 5 mm gap from edge of a specimen strain values are measured at each strain gauge position and compared. The results by ESPI method agree well with the result by strain gauge method.

  12. Strain flexibility identification of bridges from long-gauge strain measurements

    Zhang, Jian; Xia, Qi; Cheng, YuYao; Wu, ZhiShen


    Strain flexibility, defined as the strain response of a structure's element to a unit input force, is import for structural safety evaluation, but its identification is seldom investigated. A novel long-gauge fiber optic sensor has been developed to measure the averaged strain within a long gauge length. Its advantage of measuring both local and global information of the structure offers an excellent opportunity of developing the strain flexibility identification theory. In this article, the method to identify structural strain flexibility from long-gauge dynamic strain measurements is proposed. It includes the following main steps: (a) macro strain frequency response function (FRF) estimation from macro strain measurements and its feature characterization; (b) general strain modal parameter identification; (c) scaling factor calculation, and (d) strain flexibility identification. Numerical and experimental examples successfully verify the effectiveness of the proposed method.

  13. Numerical demonstration of MEMS strain sensor

    Saboonchi, Hossain; Ozevin, Didem


    Silicon has piezoresistive property that allows designing strain sensor with higher gauge factor compared to conventional metal foil gauges. The sensing element can be micro-scale using MEMS, which minimizes the effect of strain gradient on measurement at stress concentration regions such as crack tips. The challenge of MEMS based strain sensor design is to decouple the sensing element from substrate for true strain measurement and to compensate the temperature effect on the piezoresistive coefficients of silicon. In this paper, a family of MEMS strain sensors with different geometric designs is introduced. Each strain sensor is made of single crystal silicon and manufactured using deposition/ etching/oxidation steps on a n- doped silicon wafer in (100) plane. The geometries include sensing element connected to the free heads of U shape substrate, a set of two or more sensing elements in an array in order to capture strain gradients and two directional sensors. The response function and the gauge factor of the strain sensors are identified using multi-physics models that combine structural and electrical behaviors of sensors mounted on a strained structure. The relationship between surface strain and strain at microstructure is identified numerically in order to include the relationship in the response function calculation.

  14. Strain engineering of graphene: a review

    Si, Chen; Sun, Zhimei; Liu, Feng


    Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called ``straintronics''. In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected.

  15. Strain gauges as intrusion detection sensors

    Strain gauges have been studied for use as intrusion detection sensors in several applications being investigated at Sandia National Laboratories. Strain gauges are attached to a metal structure to monitor the quiescent strain in the structure. The change in the quiescent strain, when an intruder adds weight to the structure provides the alarm mechanism. The basic theory of force sensors is covered to lay the foundation for this application. In this paper, how this basic theory is applied to security sensors is discussed, and how this class of sensors is applicable to security at Department of Energy facilities is covered. Several applications are described for strain gauges as security sensors. Test results are presented from a six-month test conducted at a Department of Energy facility using the strain gauge to monitor overhead lines crossing a security perimeter. Monitoring these overhead lines with strain gauges is valuable because the cost is much less than the cost to bury the lines

  16. Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain

    Oliva-Leyva, M.; Naumis, Gerardo G.


    The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in detail the limiting case of a uniform strain. An effective Dirac Hamiltonian for nonuniform strain is thus reported, which takes into account all strain-induced effects: changes in the nearest-neighbor hopping parameters, the reciprocal lattice deformation a...

  17. A Method to Measure Reference Strain in FBG Strain Sensor Interrogation System Involving Actuators

    Rajan, Ginu; Semenova, Yuliya; Wu, Qiang; Farrell, Gerald; Wang, Pengfei


    A method for reference strain measurement for FBG strain sensor in the testing stage while applying strain using actuators like piezo translators or micro screw is introduced. Unlike conventional methods of surface mounting, in our method the strain gauge is affixed directly to the optical fibre, which allows it to use with systems where the strain is applied directly using actuators while testing the FBG sensing system. Different bonding techniques were tested and a comparison with the resul...

  18. Application of capsule type strain gage and fiber optic grating strain sensor for measurement of strain under irradiation environment

    In Japan Atomic Energy Research Institute, in-pile strain measurement techniques have been developing by using JMTR. In order to evaluate the performance of capsule type strain gage and fiber optic grating sensor under irradiation environment, the heat-up tests in electric furnace before irradiation and in-pile tests were performed. As for capsule type strain gage, it is found that gage factor almost did not change and both its electric resistance and strain output decreased by irradiation effect. A correlation was found between the change ratio of the electric resistance of the capsule type strain gage and fast neutron fluence. As for fiber optic grating sensor, it is possible to measure strain under irradiation environment below 1x1023 n/m2 (E>1 MeV) by this sensor, because in-pile temperature characteristic was in agreement with out-of-pile test results. (author)

  19. Modeling competition between yeast strains

    de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap


    We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the strains. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.

  20. Investigation of Electronic Devices for Strain Measurement

    Ričardas Masiulionis


    Full Text Available Importance of strain measuring for safety of buildings is shown. The strain monitoring should be one of the buildings security systems. Often used balanced and non-balanced Wheatstone bridge strain measurement methods are analyzed. The Wheatstone bridge method with feedback is improved. A new method based on small resistance changes by the digital balancing currents is presented. Computer and experimental models of measurement are investigated. The received results confirm theoretical assumptions.Article in Lithuanian

  1. Mechanical strain and degradation of laser heterostructures

    Ptashchenko, Alexander A.; Ptashchenko, Fedor A.; Maslejeva, Natalia V.; Sadova, Galina V.


    The effect of mechanical strain on degradation processes in GaAs-AlGaAs laser heterostructures (LHS) with stripe geometry and in light emitting diodes (LED) was experimentally studied. The strain was produced either by axial pressure or by indentation with a Wickers pyramid. We show that degradation affects the degree of polarization and the far-field distribution of laser emission. The effect of strain on the degradation intensity is estimated.

  2. Aggregation and distribution of strains in microparasites.

    Lord, C. C.; Barnard, B.; Day, K; Hargrove, J. W.; McNamara, J J; Paul, R E; Trenholme, K; Woolhouse, M. E.


    Recent research has shown that many parasite populations are made up of a number of epidemiologically distinct strains or genotypes. The implications of strain structure or genetic diversity for parasite population dynamics are still uncertain, partly because there is no coherent framework for the interpretation of field data. Here, we present an analysis of four published data sets for vector-borne microparasite infections where strains or genotypes have been distinguished: serotypes of Afri...

  3. Flat band superconductivity in strained Dirac materials

    Kauppila, V. J.; Aikebaier, F.; Heikkilä, T. T.


    We consider superconducting properties of a two-dimensional Dirac material such as graphene under strain that produces a flat band spectrum in the normal state. We show that in the superconducting state, such a model results in a highly increased critical temperature compared to the case without the strain, inhomogenous order parameter with two-peak shaped local density of states and yet a large and almost uniform and isotropic supercurrent. This model could be realized in strained graphene o...

  4. Strain rate sensitivity of automotive sheet steels : influence of plastic strain, strain rate, temperature, microstructure, bake hardening and pre-strain

    Larour, Patrick


    This experimental work shows the different parameters influencing the strain rate sensitivity behaviour of automotive sheet steel grades in crash conditions. Most investigations have been performed in the strain rate range [0,001-200/s] and temperature range [233-373K] with servohydraulic tensile testing machines. Additional Split-Hopkinson bar testing results up to 1000/s have also been included at room temperature. The focus has been laid on the “apparent” strain rate sensitivity, determine...

  5. Nonlinear strain gradient elastic thin shallow shells

    Lazopoulos, K.A.


    Abstract The governing equilibrium equations for strain gradient elastic thin shallow shells are derived, considering non-linear strains and linear constitutive strain gradient elastic relations. Adopting Kirchhoff's theory of thin shallow structures, the equilibrium equations, along with the boundary conditions, are formulated through a variational procedure. It turns out that new terms are introduced, indicating the importance of the cross-section area in bending of thin plates. ...

  6. High strain rate loading of zircaloy

    High strain rate tensile loading behaviours of Zircaloys subjected to various treatments were investigated at room temperature and at 3000C, and compared with those of static cases. It was observed that the dynamic stress-strain profiles were different depending upon the specimen treatment and that the higher peak stress and the lower sectional area reduction were always recognized in the high strain rate cases

  7. Film germanium strain gauges for cryogenic temperatures

    Strain-measuring characteristics of strain gauges (SG) based on germanium films on gallium arsenide designed for operation in 4-100 K temperature interval and strain range ε∼(±0.3%) are presented. SG are characterized by weak temperature dependences of resistance and strain sensitivity in the temperature range measured. It is shown that in the low-temperature region SG based on heteroepitaxial germanium films on gallium arsenide are no worse than the best domestic and foreign semiconducting and metal SG and are perspective for cryogenic object diagnostics under magnetic field effect

  8. High strain rate damage of Carrara marble

    Doan, Mai-Linh; Billi, Andrea


    Several cases of rock pulverization have been observed along major active faults in granite and other crystalline rocks. They have been interpreted as due to coseismic pervasive microfracturing. In contrast, little is known about pulverization in carbonates. With the aim of understanding carbonate pulverization, we investigate the high strain rate (c. 100 s-1) behavior of unconfined Carrara marble through a set of experiments with a Split Hopkinson Pressure Bar. Three final states were observed: (1) at low strain, the sample is kept intact, without apparent macrofractures; (2) failure is localized along a few fractures once stress is larger than 100 MPa, corresponding to a strain of 0.65%; (3) above 1.3% strain, the sample is pulverized. Contrary to granite, the transition to pulverization is controlled by strain rather than strain rate. Yet, at low strain rate, a sample from the same marble displayed only a few fractures. This suggests that the experiments were done above the strain rate transition to pulverization. Marble seems easier to pulverize than granite. This creates a paradox: finely pulverized rocks should be prevalent along any high strain zone near faults through carbonates, but this is not what is observed. A few alternatives are proposed to solve this paradox.

  9. Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

    One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other

  10. The treatment of secondary strains within a strain-based failure assessment diagram

    In a companion paper, proposals for the shape of a strain-based failure assessment diagram (FAD) have been made. The developments in that paper and in related works on strain-based fracture assessment have largely been for remotely applied strains, such as those produced by welding. This paper re-writes existing methods for treating secondary stresses within stress-based FADs in the framework of the proposed strain-based FAD. It is shown that residual strains must be included fully in the elastic regime but at large applied strains their contribution to fracture can be relaxed considerably. Practical methods for inclusion of secondary strains within the strain-based FAD are then developed and shown to be conservative relative to some detailed finite element calculations. -- Highlights: ► Methods for treating secondary stresses are written in the framework of a strain-based FAD. ► Residual strains have a full effect in the elastic regime but their influence is relaxed considerably at large applied strains. ► Practical methods for inclusion of secondary strains within a strain-based FAD are developed. ► The methods are shown to be conservative relative to some detailed finite element calculations

  11. True stress–strain curves of cold worked stainless steel over a large range of strains

    True stress–strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress–strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress–strain curves. The stress–strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress–strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress–strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg–Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be nS = 0.5

  12. Studies on induced mutation in hawthorn (Crataegus pinnatifida bge) through radiation

    Sprouted annual shoots and one year-old seedlings of hawthorn were treated with 60Co γ-rays. The results showed that injury level was heavier and the number of sprouted plants was decreased significantly with increasing dose. With cut back pruned method, buds on low position of seedlings were sprouted. At low irradiation doses, level of radiation injury of seedlings was decreased with increasing diameter. When sprouted annual shoots were treated with different doses, the responses were different between various varieties. Fruit on most branches of Miyun became smaller after treatment. Fruit on branches of Large Golden Star showed variation in both larger and smaller directions. Through treatment, seed number in fruit had no significant change. Several good mutants (large fruit, spur-high yield and short fruit stalk for ornamental types) were selected

  13. A comparison of eastern North American seismic strain-rates to glacial rebound strain-rates

    James, Thomas S.; Bent, Allison L.


    Glacial rebound strain-rates computed using a simple Laurentide glacial loading model are of the order of 10(exp -9) per year within the region of glaciation and extending several hundred kilometers beyond. The horizontal strain-rates receive approximately equal contributions from horizontal and vertical velocities, a consequence of the spherical geometry adopted for the Earth model. In the eastern United States and southeastern Canada the computed strain-rates are 1-3 orders of magnitude greater than an estimate of the average seismic strain-rate (Anderson, 1986) and approximately 1 order of magnitude greater than predicted erosional strain-rates. The predicted glacial rebound strain-rates are not, in general, oriented in such a way as to augment the observed state of deviatoric stress, possibly explaining why the seismic strain-rates are much smaller than the glacial rebound strain-rates. An exception to this may be seismically active regions in the St. Lawrence valley.

  14. Predicting creep rupture from early strain data

    To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40-165 MPa) and temperature (125-350 deg. C) were fitted to the models in the strain range of 0.1-38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is

  15. The Stress-Strain Condition Estimation of Detail in Crack Tip by Integral Strain Gauges

    Syzrantsev, V.; Syzrantseva, K.


    The paper considers the task of stress-strain condition calculation of experimental sample in fatigue crack tip on weld boundary at its cyclic deforming. For this task decision authors use the information obtained by original means of cyclic strains measurement: Integral Strain Gauges. The results of carried experimental researches are compared with data of stress-strain condition estimation of detail in crack tip calculated by Finish Element Method.

  16. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    Blucher, J.T.; Knudsen, Per; Grant, N.J.


    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with...... decreasing strain rate, above 500 F, and with increasing temperature; ductility at fracture in tension test is shown to be important factor in determining life under conditions of test. (20318)...

  17. Multiplying decomposition of stress/strain, constitutive/compliance relations, and strain energy

    Lee, Hyunsuk; Kim, Jinkyu


    To account for phenomenological theories and a set of invariants, stress and strain are usually decomposed into a pair of pressure and deviatoric stress and a pair of volumetric strain and deviatoric strain. However, the conventional decomposition method only focuses on individual stress and strain, so that cannot be directly applied to either formulation in Finite Element Method (FEM) or Boundary Element Method (BEM). In this paper, a simpler, more general, and widely applicable decompositio...

  18. Influence of Azospirillum Strains on the Nodulation of Clovers by Rhizobium Strains

    Plazinski, Jacek; Rolfe, Barry G.


    Mixed cultures of several Azospirillum and Rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with R. trifolii alone. Azospirillum strains affected the nodulation process at a precise cell ratio (R. trifolii/Azospirillum cells) and time of inoculation. All Azospirillum strains used showed a variation in their ability to inhibit or enhance nodulation by R. trifolii strains. When nonviable cel...

  19. Crack growth monitoring by strain measurements

    Cracks detected during in-service inspections are not always removed when they are judged as hazardous. It is important to monitor the crack growth in order to secure the integrity of the cracked components. The author and a co-worker proposed a crack growth monitoring method, in which the elastic strain caused by internal pressure is continuously measured. The elastic strain acting at the outside surface of a pressurized pipe changes due to growth of a crack in the inside surface, and the magnitude of its change depends on the growth size. In this study, the author uses multiple strain gages to monitor the elastic strain acting on the cracked part of a pipe. An axial crack was introduced at the butt welding portion inside a carbon steel pipe. The strains were then measured under static internal pressure. The crack size was estimated based on the change in strains measured by strain gages attached onto the outside surface of the pipe. This study reveals that such a monitoring procedure could successfully identify not only the crack depth but also the surface length. The maximum estimation errors were 2.2 mm and 0.97 mm for the surface length and depth, respectively. The accuracy of the estimation improved as the number of strain gages increased. It was also apparent that the residual stress had subtle effect on the size estimation, albeit it may have significant influence when the crack propagates. (author)

  20. On lower order strain gradient plasticity theories

    Niordson, Christian Frithiof; Hutchinson, J. W.


    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the...

  1. On lower order strain gradient plasticity theories

    Niordson, Christian Frithiof; Hutchinson, J. W.


    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the...

  2. Nanocomposite Strain Gauges Having Small TCRs

    Gregory, Otto; Chen, Ximing


    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  3. High-Temperature Resistance Strain Gauges

    Lei, Jih-Fen


    Resistance strain gauges developed for use at high temperatures in demanding applications like testing aircraft engines and structures. Measures static strains at temperatures up to 800 degrees C. Small and highly reproducible. Readings corrected for temperature within small tolerances, provided temperatures measured simultaneously by thermocouples or other suitable devices. Connected in wheatstone bridge.

  4. Whole genome sequences of four Brucella strains.

    Ding, Jiabo; Pan, Yuanlong; Jiang, Hai; Cheng, Junsheng; Liu, Taotao; Qin, Nan; Yang, Yi; Cui, Buyun; Chen, Chen; Liu, Cuihua; Mao, Kairong; Zhu, Baoli


    Brucella melitensis and Brucella suis are intracellular pathogens of livestock and humans. Here we report four genome sequences, those of the virulent strain B. melitensis M28-12 and vaccine strains B. melitensis M5 and M111 and B. suis S2, which show different virulences and pathogenicities, which will help to design a more effective brucellosis vaccine. PMID:21602346

  5. Job strain and time to pregnancy

    Hjollund, N H; Jensen, Tina Kold; Bonde, J P; Henriksen, T B; Kolstad, H A; Andersson, A M; Ernst, E; Giwercman, A; Skakkebaek, N E; Olsen, J


    The association between fertility and job strain defined as high job demands and low job control has not previously been studied. A follow-up study was conducted with prospective collection of information on job strain among women, achievement of pregnancy, and potential confounding variables....

  6. Marital Role Strain and Sexual Satisfaction.

    Frank, Ellen; And Others


    Responses to a questionnaire pertaining to discrepancies between an individual's ideal and actual marital role behaviors and level of sexual satisfaction indicated lower levels of role strain in nonpatient couples. A higher level of role strain correlated with increased sexual dissatisfaction. (Author)

  7. A Natural Vaccine Candidate Strain Against Cholera



    El Tor Vibrio cholerae(EVC)strains may be classified into two kinds-epidemigenic(EEVC)strains and non-epidemigenic(NEEVC)strains-based on a phage-biotyping system.A large number of EEVC strains have been screened for toxigenic and putative colonization attributes.One such naturally occurring strain(designated IEM101)has been found which is devoid of genes encoding cholera toxin(CT),accessory cholera enterotoxin(ACE),zonula occludens toxin(ZOT),but possesses RS1 sequences and toixn-coregulated pilus A gene(tcpA)although tcpA is poorly expressed.It expresses type B pili but does not posses type C pili.It is an El Tor Ogawa strain and does not cause fluid accumulation in rabbit ileal loop tests.Active immunization of rabbits with strain IEM101 elicited good protection against challenge with virulent strains of V.cholerae Ol.Oral administration cased no side effects in 15 human volunteers.colonized the gut for four to ten days and elicited good immune responses.

  8. On fracture in finite strain gradient plasticity

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof


    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are...... investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... predictions. These differences increase significantly when large strains are taken into account, as a consequence of the contribution of strain gradients to the work hardening of the material. The magnitude of stress elevation at the crack tip and the distance ahead of the crack where GNDs significantly alter...

  9. Mechanical strain effects on black phosphorus nanoresonators.

    Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon


    We perform classical molecular dynamics simulations to investigate the effects of mechanical strain on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile strain, with uniaxial strain in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large strains, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum strain for quality factor enhancement. PMID:26649476

  10. Dark field electron holography for strain measurement

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: → Step by step explanation of the dark field electron holography technique. → Presentation of the theoretical equations to obtain quantitative strain map. → Description of experimental parameters influencing dark field holography results. → Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  11. Pseudomagnetic fields and triaxial strain in graphene

    Settnes, Mikkel; Power, Stephen; Jauho, Antti-Pekka


    Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions ("pseudoma......Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions......-binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of rotating the strain direction with respect to the underlying graphene lattice, and varying the size of the pseudomagnetic dot....

  12. Review of graphene-based strain sensors

    Zhao Jing; Zhang Guang-Yu; Shi Dong-Xia


    In this paper,we review various types of graphene-based strain sensors.Graphene is a monolayer of carbon atoms,which exhibits prominent electrical and mechanical properties and can be a good candidate in compact strain sensor applications.However,a perfect graphene is robust and has a low piezoresistive sensitivity.So scientists have been driven to increase the sensitivity using different kinds of methods since the first graphene-based strain sensor was reported.We give a comprehensive review of graphene-based strain sensors with different structures and mechanisms.It is obvious that graphene offers some advantages and has potential for the strain sensor application in the near future.

  13. Dark field electron holography for strain measurement

    Beche, A., E-mail: [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)


    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  14. Near tip strain evolution under cyclic loading

    J. Tong


    Full Text Available The concept of ratchetting strain as a crack driving force in controlling crack growth has previously been explored at Portsmouth using numerical approaches for nickel-based superalloys. In this paper, we report the first experimental observations of the near-tip strain evolution as captured by the Digital Image Correlation (DIC technique on a compact tension specimen of stainless steel 316L. The evolution of the near-tip strains with loading cycles was studied whilst the crack tip was maintained stationary. The strains were monitored over the selected distances from the crack tip for a given number of cycles under an incremental loading regime. The results show that strain ratchetting does occur with load cycling, and is particularly evident close to the crack tip and under higher loads. A finite element model has been developed to simulate the experiments and the simulation results are compared with the DIC measurements.

  15. Microstructure and strain hardening of steels

    In the present work, the relation between metallurgical microstructures and strain hardening behaviour of both fcc and bcc steels was investigated. In order to obtain large strains, a new experimental method was developed and the data mathematically prepared for further analysis. It was found that the strain hardening rate increases with decreasing particle size or increasing yield stress of ferritic steels. The strain hardening rate is found to be correlated to the specific microstructure. A new model was formulated to describe large deformations. This has been done on the basis of already existing models. According to the new model, the strain hardening in stage IV is caused by the dislocations in cell interiors instead of those in the cell walls. (orig.)

  16. Nanoscale strain mapping in battery nanostructures

    Ulvestad, A., E-mail:; Kim, J. W.; Dietze, S. H.; Shpyrko, O. G. [Department of Physics, University of California-San Diego, La Jolla, California 92093-0319 (United States); Cho, H. M.; Meng, Y. S. [Department of NanoEngineering, University of California-San Diego, La Jolla, California 92093-0448 (United States); Harder, R. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Fohtung, E. [Manuel Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003 (United States)


    Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi{sub 0.5}Mn{sub 1.5}O{sub 4−δ} cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn{sup 3+}. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

  17. Irreducible decomposition of strain gradient tensor in isotropic strain gradient elasticity

    Lazar, Markus


    In isotropic strain gradient elasticity, we decompose the strain gradient tensor into its irreducible pieces under the n-dimensional orthogonal group O(n). Using the Young tableau method for traceless tensors, four irreducible pieces (n>2), which are canonical, are obtained. In three dimensions, the strain gradient tensor can be decomposed into four irreducible pieces with 7+5+3+3 independent components whereas in two dimensions, the strain gradient tensor can be decomposed into three irreducible pieces with 2+2+2 independent components. The knowledge of these irreducible pieces is extremely useful when setting up constitutive relations and strain energy.

  18. Strain relaxation in nano-patterned strained-Si/SiGe heterostructure on insulator

    In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by Electron-Beam Lithography (EBL) and Reactive-Ion Etching (RIE). The strain relaxation in the patterned strained Si on SiGe-on-insulator (SGOI) was investigated by high-resolution UV micro-Raman spectroscopy. The Raman measurements before and after patterning indicate that most of the strain in the top strained Si is maintained until scaling down to 300 nm, and relaxation of <15% is observed in pillars with a dimension of 150 nm x 150 nm. In the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is small, which is mainly attributed to the fully relaxed and dislocation-free SiGe virtual substrate fabricated by modified Ge condensation.

  19. Strain mapping analysis of textile composites

    Ivanov, Dmitry; Ivanov, Sergey; Lomov, Stepan; Verpoest, Ignaas


    The focus of the work is meso-scale analysis (scale level of the fabric unit cell) of textile composite deformation and failure. The surface strain measurement is used for: (1) experimental investigation, which includes study of strain distribution at various stages of deformation, plasticity detection, damage initiation; (2) numerical validation of the correspondent finite element (FE) models. Two examples are considered: carbon-epoxy triaxial-braided and glass polypropylene-woven composite. The surface strain measurement (by digital image correlation technique) accompanies the tensile tests, aiming at: (1) elastic anisotropic constants characterisation, (2) study of non-linear material behaviour (for the thermoplastic composite), (3) control of homogeneity of the macro-strain distribution, and (4) analysis of damage initiation in brittle composites. Validation of meso-FE models by strain measurements encounters difficulties arising from (1) resolution of the strain measurements, (2) irregularities of the initial structure such as random layer nesting, ply interaction, and deviation of yarns from their theoretical position, which affects the measured strain fields. The paper discusses these difficulties and demonstrates a qualitative agreement with the FE analysis of idealised composite configurations.

  20. Thermoresistance in radioresistant strains of 'Drosophila nebulosa'

    The detection of thermoresistance in radioresistant strains of 'D. nebulosa' is described, as well as some conclusions on the genetic nature of these differences are presented. The strains used in this experiment were MF 204, from 'Morro de Ferro', in Pocos de Caldas (MG) (one of the biggest radioactive anomalies in the world) whose radioresistance is due to its additive genetic components (Kratz, 1973 and 1975); 85(87) R, an induced radioresistant strain; and MF K a control 'pooled' strain obtained near 'Morro do Ferro'. Survival tests, 72 hours after temperature shocks, performed in the interval of 360C to 390C showed a decreasing gradient of thermoresistance with the following regression coefficients: MF 204 b=-5,4; 85(87)R b=-7,2 and MF K b=-7,9. Bifactorial analysis (strains and sexes) performed at 380C and 390C confirmed differences among strains (P<01 and P<0,5, respectively) suggesting a poligenic control of the thermoresistance. Consitent and verified relations among strains, being simultaneously resistant to different kinds of mutagenic factors, are considered evidence of the existence of general mechanisms in mutagenic control. Therefore, the results, together with results of Tsukamoto, Ogaki and Kikkawa 1957, Ogaki 1962 and Nakashima-Tanaka 1966, Parsons 1969, add to the hypotheses of the existence of general mechanisms in mutagenic control

  1. Piezoelectric strain sensor/actuator rosettes

    In-plane anisotropy in the linear piezoelectric constitutive law for [011]c cut and poled PMN–0.29PT is demonstrated to enable its use as a sensor/actuator rosette. The equations for a 0°/45°/90° rosette are developed using the conditions of coupling between the in-plane strain of the crystal and a substrate, and zero out-of-plane stress on the crystal (plane stress conditions in the crystals). The crystals are bonded to a substrate aluminum plate that is instrumented with strain gages next to the crystals. The plate is subjected to bending about different axes and the resulting electric displacement change of the crystals is monitored. The strain components calculated using the change of electric displacement are compared with the strain components measured using strain gages. This sensor/actuator rosette approach is demonstrated to enable both sensing principal strain components and actuating principal strains in an electronically controllable direction. (fast track communication)


    Duc Tran


    Full Text Available Dunaliella strains were isolated from a key site for salt production in Vietnam (Vinh Hao, Binh Thuan province. The strains were identified based on Internal Transcribed Spacer (ITS markers. The phylogenetic tree revealed these strains belong to the clades of Dunaliella salina and Dunaliella viridis. Results of this study confirm the ubiquitous nature of Dunaliella and suggest that strains of Dunaliella salina might be acquired locally worldwide for the production of beta-carotene. The identification of these species infers the presence of other Dunaliella species (Dunaliella tertiolecta, Dunaliella primolecta, Dunaliella parva, but further investigation would be required to confirm their presence in Vietnam. We anticipate the physiological and biochemical characteristics of these local species will be compared with imported strains in a future effort. This will facilitate selection of strains with the best potential for exploitation in the food, aquaculture and biofuel industries. The Dunaliella strains isolated and identified in this study are maintained at the Laboratory of Algal Biotechnology, International University and will be made available for research and educational institutions.

  3. Strain gradient plasticity: energetic or dissipative?

    Fleck, N. A.; Willis, J. R.


    For an infinite slab of strain gradient sensitive material subjected to plane-strain tensile loading, computation established and analysis confirmed that passivation of the lateral boundaries at some stage of loading inhibits plastic deformation upon further loading. This result is not surprising in itself except that, remarkably, if the gradient terms contribute to the dissipation, the plastic deformation is switched off completely and only resumes at a clearly defined higher load, corresponding to a total strain , say. The analysis presented in this paper confirms the delay of plastic deformation following passivation and determines the exact manner in which the plastic flow resumes. The plastic strain rate is continuous at the exact point of resumption of plastic flow and, for the first small increment in the imposed total strain, the corresponding increment in plastic strain, , is proportional to . The constant A in the relation , where denotes the plastic strain increment at the centre of the slab, has been determined explicitly; it depends on the hardening modulus of the material. The presence of energetic gradient terms has no effect on the value of unless the dissipative terms are absent, in which case passivation reduces the rate of plastic deformation but introduces no delay. This qualitative effect of dissipative gradient terms opens the possibility of experimental discrimination of their presence or absence. The analysis employs an incremental variational formulation that is likely to find use in other problems.

  4. Revisiting the gauge fields of strained graphene

    Iorio, Alfredo; Pais, Pablo(Centro de Estudios Científicos (CECS), Casilla, 1469 , Valdivia, Chile)


    We show that, when graphene is only subject to strain, the spin connection gauge field that arises plays no measurable role, but when intrinsic curvature is present and strain is small, spin connection dictates most the physics. We do so by showing that the Weyl field associated with strain is a pure gauge field and no constraint on the $(2+1)$-dimensional spacetime appears. On the other hand, for constant intrinsic curvature that also gives a pure-gauge Weyl field, we find a classical manife...



    The strain distribution of equal-cross section lateral extrusion(ECSLE) has been simulated by finite element method. Considering the effect of friction and the width of sample, the simulation results are very close to the reality. The simulated results showed that, around the corner of die, the strain is distributed by sharp layers, and the gradient of the layers is very large, which means that the deformation is just plane shear deformation; the larger the width of sample or the smaller the friction, the more uniform the strain distribution is.

  6. Semiconductor strain metrology principles and applications

    Wong, Terence KS


    This book surveys the major and newly developed techniques for semiconductor strain metrology. Semiconductor strain metrology has emerged in recent years as a topic of great interest to researchers involved in thin film and nanoscale device characterization. This e-book employs a tutorial approach to explain the principles and applications of each technique specifically tailored for graduate students and postdoctoral researchers. Selected topics include optical, electron beam, ion beam and synchrotron x-ray techniques. Unlike earlier references, this e-book specifically discusses strain metrol

  7. Self-diffusion in compressively strained Ge

    Under a compressive biaxial strain of ∼ 0.71%, Ge self-diffusion has been measured using an isotopically controlled Ge single-crystal layer grown on a relaxed Si0.2Ge0.8 virtual substrate. The self-diffusivity is enhanced by the compressive strain and its behavior is fully consistent with a theoretical prediction of a generalized activation volume model of a simple vacancy mediated diffusion, reported by Aziz et al.[Phys. Rev. B 73, 054101 (2006)]. The activation volume of (-0.65±0.21) times the Ge atomic volume quantitatively describes the observed enhancement due to the compressive biaxial strain very well.

  8. Strain gage balances and buffet gages

    Ferris, A. T.


    One-piece strain gage force balances were developed for use in the National Transonic Facility (NTF). This was accomplished by studying the effects of the cryogenic environment on materials, strain gages, cements, solders, and moisture proofing agents, and selecting those that minimized strain gage output changes due to temperature. In addition, because of the higher loads that may be imposed by the NTF, these balances are designed to carry a larger load for a given diameter than conventional balances. Full cryogenic calibrations were accomplished, and wind tunnel results that were obtained from the Langley 0-3-Meter Transonic Cryogenic Tunnel were used to verify laboratory test results.

  9. Strains in pyrolytic graphite under irradiation

    The studies of strains in pyrolytic graphite caused by development of amorphization in the irradiation zone showed that the local strains attain tens of percent; their distribution is inhomogeneous both in magnitude and in sign. The tendency toward formation of a biaxial field of compressive strains becomes marked with an increase in the fluence, although the formation of small regions in the form of narrow sectors within whose boundaries compression is observed in the radial direction and extension is observed in the tangential direction is also possible. 14 refs., 6 figs

  10. Stability of germanene under tensile strain

    Kaloni, Thaneshwor P.


    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  11. Unit cell of strained GeSi

    The local structure within the unit cell of strained-GeSi layers grown on Si(001) has been examined by polarization-dependent extended x-ray-absorption fine structure. First-neighbor bond lengths are found to deviate only slightly from their unstrained values; however, the distortion of the cubic-unit cell by strain leads to measurable polarization-dependent changes in first-shell coordination and second-shell distances. A unifying picture of bond lengths and elasticity in strained-layer semiconductors is presented. copyright 1997 The American Physical Society

  12. Construction of Killer Wine Yeast Strain

    Seki, Tetsuji; Choi, Eon-Ho; Ryu, Dewey


    A double-stranded RNA plasmid which confers the superkiller phenotype was transferred into a wine yeast (Montrachet strain 522) and its leucine-requiring derivative (strain 694) by cytoduction, using the protoplast fusion technique. The killer wine yeast constructed completely suppressed the growth of killer-sensitive strains of Saccharomyces cerevisiae in yeast extract-peptone-glucose medium at pH 4.5, whereas the killer effect was somewhat decreased at pH 3.5. The wine yeast harboring the k...

  13. A new radial strain and strain rate estimation method using autocorrelation for carotid artery

    Ye, Jihui; Kim, Hoonmin; Park, Jongho; Yeo, Sunmi; Shim, Hwan; Lim, Hyungjoon; Yoo, Yangmo


    Atherosclerosis is a leading cause of cardiovascular disease. The early diagnosis of atherosclerosis is of clinical interest since it can prevent any adverse effects of atherosclerotic vascular diseases. In this paper, a new carotid artery radial strain estimation method based on autocorrelation is presented. In the proposed method, the strain is first estimated by the autocorrelation of two complex signals from the consecutive frames. Then, the angular phase from autocorrelation is converted to strain and strain rate and they are analyzed over time. In addition, a 2D strain image over region of interest in a carotid artery can be displayed. To evaluate the feasibility of the proposed radial strain estimation method, radiofrequency (RF) data of 408 frames in the carotid artery of a volunteer were acquired by a commercial ultrasound system equipped with a research package (V10, Samsung Medison, Korea) by using a L5-13IS linear array transducer. From in vivo carotid artery data, the mean strain estimate was -0.1372 while its minimum and maximum values were -2.961 and 0.909, respectively. Moreover, the overall strain estimates are highly correlated with the reconstructed M-mode trace. Similar results were obtained from the estimation of the strain rate change over time. These results indicate that the proposed carotid artery radial strain estimation method is useful for assessing the arterial wall's stiffness noninvasively without increasing the computational complexity.

  14. Information about the Current Strain of Clostridium difficile

    ... treatment of this epidemic strain different? How does fluoroquinolone resistance affect management of this strain? What should ... guidelines on internet) Top of page How does fluoroquinolone resistance affect management of this strain? Increased fluoroquinolone ...

  15. Screening of Trichoderma strains tolerant to benzimidazole

    LIU Kai-qi; XIANG Mei-mei; LIU Ren; ZENG Yong-san; ZHOU Hong-zi; YU Jin-feng; JIANG Xin-yin; ZHANG Yue-li


    @@ The screening of isolates and the assay of biocontrol mechanisms of Trichoderma were studied systematically in laboratory and greenhouse in vivo. The proteins tolerant to benzimidazole in Trichoderma strains were purified, and their physical and chemical properties were detected. Compared their biological activities in vitro and vivo in greenhouse, nine biocontrol strains (including Ty- 10-2, LTR-2, Tj-5-1, Tj-5-4, Ty- 11-1, Tj-11-3, Ty- 11-3, Tj-3-3-2, Tj-3-3-4) were screened. These biocontrol strains had faster rates of growth and higher inhibition to gray mould (Bortrytis cinerea),and the inhibition was stable. The effects of controlling gray mould in greenhouse with the screened Trichoderma strains were 70 % and 50 % in vivo.

  16. Axillary vein thrombosis mimicking muscular strain.

    Louis, J.


    Axillary vein thrombosis may occur on strenuous activity with a clinical picture similar to a simple strain. It carries significant morbidity but a good outcome is possible with early treatment. The aetiology, investigation, and treatment are discussed.

  17. Energy Harvesting Wireless Strain Networks Project

    National Aeronautics and Space Administration — Prime Research LC (PPLC) and Virginia Tech (VT) propose to develop an energy harvesting wireless strain node technology that utilizes single-crystal piezoelectric...

  18. Five challenges in modelling interacting strain dynamics

    Paul S. Wikramaratna


    Full Text Available Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity accumulates over multiple exposures.

  19. [Improvement of Trichoderma strains for biocontrol].

    Benítez, T; Rey, M; Delgado-Jarana, J; Rincón, A M; Limón, M C


    The use of the fungal genus Trichoderma to control fungal plant diseases is a promising alternative to the use of chemical compounds. The aim of this work has been to obtain Trichoderma strains with improved capacity as biological control agents. To do so, the hydrolytic capacity on fungal cell walls of strains of the fungus Trichoderma harzianum has been increased. On one hand, transformation experiments with genes which coded for chitinases and glucanases have been carried out in T. harzianumstra ins. On the other hand, the medium composition has also been modified in order to eliminate proteolytic degradation of some of the overproduced enzymes. Finally, hybrid chitinolytic enzymes with substrate-binding domains have been produced as an alternative to obtain improved biocontrol strains. The transformant strains, when compared with the wild type, showed improved antifungal capacity against the phytopathogenic fungus Rhizoctonia solani, in in vitro experiments. PMID:15762779

  20. Dynamic Force Measurement with Strain Gauges

    Lee, Bruce E.


    Discusses the use of four strain gauges, a Wheatstone bridge, and an oscilloscope to measure forces dynamically. Included is an example of determining the centripetal force of a pendulum in a general physics laboratory. (CC)

  1. Design parameters for borehole strain instrumentation

    Gladwin, Michael T.; Hart, Rhodes


    The response of a borehole strain meter to hydrostatic and shear deformations in an isotropic medium is calculated to facilitate optimum instrument design and produce instrument response factors for parameters typically encountered in installed instruments. Results for an empty borehole are first compared with results for an instrument in intimate contact with the surrounding rock. The effects of the grout used to install the instrument are then examined. Where possible, analytic forms for the response factors are given. Results for typical installations are then presented in graphical form for optimizing instrument design in an environment of known elastic parameters. Alternatively, the results may be applied in the measurement of unknown strain signals, to correct for instrument response or to provide in-situ estimates of the elastic properties of the environment by examination of observed strain response to known strain signals.

  2. Strain Rate Induced Amorphization in Metallic Nanowires

    Qi, Y.; Cagin, T.; Goddard, W.A. III [Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 (United States); Ikeda, H.; Samwer, K.; Johnson, W.L. [Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena, California 91125 (United States)


    Using molecular dynamics simulations with a many-body force field, we studied the deformation of single crystal Ni and NiCu random alloy nanowires subjected to uniform strain rates but kept at 300thinspthinspK. For all strain rates, the Ni nanowire is elastic up to 7.5{percent} strain with a yield stress of 5.5thinspthinspGPa, far above that of bulk Ni. At high strain rates, we find that for both systems the crystalline phase transforms continuously to an amorphous phase, exhibiting a dramatic change in atomic short-range order and a near vanishing of the tetragonal shear elastic constant perpendicular to the tensile direction. This amorphization which occurs directly from the homogeneous, elastically deformed system with no chemical or structural inhomogeneities exhibits a new mode of amorphization. {copyright} {ital 1999} {ital The American Physical Society}

  3. 3D Morphing Using Strain Field Interpolation

    Han-Bing Yan; Shi-Min Hu; Ralph R Martin


    In this paper, we present a new technique based on strain fields to carry out 3D shape morphing for applicationsin computer graphics and related areas.Strain is an important geometric quantity used in mechanics to describe the deformation of objects.We apply it in a novel way to analyze and control deformation in morphing.Using position vector fields, the strain field relating source and target shapes can be obtained.By interpolating this strain field between zero and a final desired value we can obtain the position field for intermediate shapes.This method ensures that the 3D morphing process is smooth.Locally, volumes suffer minimal distortion, and no shape jittering or wobbling happens: other methods do not necessarily have these desirable properties.We also show how to control the method so that changes of shape (in particular, size changes) vary linearly with time.

  4. Five challenges in modelling interacting strain dynamics

    Wikramaratna, Paul S; Kurcharski, Adam; Gupta, Sunetra;


    Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings...... with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to...... useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how...

  5. Strain Gauges Mounted To Retain Calibration

    Butler, Barry L.


    Silicon-based semiconductor strain gauges mounted in such way they retain original calibration for several years instead of few months. Improvement effected by bonding gauges to ceramic substrates with glasses instead of epoxies as adhesives.

  6. Broken Bones, Sprains, and Strains (For Parents)

    ... 5 Things to Know About Zika & Pregnancy Broken Bones, Sprains, and Strains KidsHealth > For Parents > Broken Bones, ... home. What to Do: For a Suspected Broken Bone: Do not move a child whose injury involves ...

  7. Strain field of a buried oxide aperture

    Kießling, F.; Niermann, T.; Lehmann, M.; Schulze, J.-H.; Strittmatter, A.; Schliwa, A.; Pohl, U. W.


    The strain field of an AlOx current aperture, fabricated by selective oxidation of an AlAs/GaAs layer buried in a circular GaAs mesa, is studied. Components of the strain tensor for a thin cross-section lamella cut out of such a structure are evaluated from dark-field electron holography, proving the validity of simulations based on linear elasticity. Simulation of the entire structure is utilized to prepare mesa surfaces with tailored strain fields for controlling the nucleation site of InGaAs quantum dots. The experimental proof of strain simulations allows estimating the magnitude of piezoelectricity, yielding for the studied mesa structures a piezoelectric potential up to 50 mV.

  8. Microalgal Strains Sent to External Users

    National Oceanic and Atmospheric Administration, Department of Commerce — Over 200 microalgal strains maintained in the Milford Microalgal Culture Collection are available to aquaculture facilities and researchers. Approximately 100...

  9. Review of strain buckling: analysis methods

    This report represents an attempt to review the mechanical analysis methods reported in the literature to account for the specific behaviour that we call buckling under strain. In this report, this expression covers all buckling mechanisms in which the strains imposed play a role, whether they act alone (as in simple buckling under controlled strain), or whether they act with other loadings (primary loading, such as pressure, for example). Attention is focused on the practical problems relevant to LMFBR reactors. The components concerned are distinguished by their high slenderness ratios and by rather high thermal levels, both constant and variable with time. Conventional static buckling analysis methods are not always appropriate for the consideration of buckling under strain. New methods must therefore be developed in certain cases. It is also hoped that this review will facilitate the coding of these analytical methods to aid the constructor in his design task and to identify the areas which merit further investigation

  10. Tuning strain in flexible graphene nanoelectromechanical resonators

    Guan, Fen; Kumaravadivel, Piranavan; Averin, Dmitri V.; Du, Xu


    The structural flexibility of low dimensional nanomaterials offers unique opportunities for studying the impact of strain on their physical properties and for developing innovative devices utilizing strain engineering. A key towards such goals is a device platform which allows the independent tuning and reliable calibration of the strain. Here, we report the fabrication and characterization of graphene nanoelectromechanical resonators (GNEMRs) on flexible substrates. Combining substrate bending and electrostatic gating, we achieve the independent tuning of the strain and sagging in graphene and explore the nonlinear dynamics over a wide parameter space. Analytical and numerical studies of a continuum mechanics model, including the competing higher order nonlinear terms, reveal a comprehensive nonlinear dynamics phase diagram, which quantitatively explains the complex behaviors of GNEMRs.

  11. Survival and activity of individual bioaugmentation strains

    Dueholm, Morten Simonsen; G. Marquesa, Irina; Karst, Søren Michael;


    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now a...

  12. Strain imaging by Bragg edge neutron transmission

    Santisteban, J R; Fitzpatrick, M E; Steuwer, A; Withers, P J; Daymond, M R; Johnson, M W; Rhodes, N; Schooneveld, E M


    The Bragg edges appearing in the transmitted time-of-flight spectra of polycrystalline materials have been recorded using a two-dimensional array of detectors. Subsequent analysis has enabled maps of the elastic strain to be produced.

  13. Some remarks on the strain decomposition

    F. Nicot; Darve, F.


    An impressive amount of constitutive relations have been developed in the past few decades. With respect to the class of elasto-plastic phenomenological models, elastic and plastic strain decomposition is generally stated as a basic assumption, so as to treat the elastic (i.e., recoverable) and plastic (i.e., unrecoverable) parts of the strains separately. For incrementally nonlinear relations this decomposition is not possible. In a first part of this paper a detailed discussion of elastic a...

  14. Framework for Concentrated Strain Deployable Trusses

    Mejia-Ariza, Juan Manuel


    This research presents a simplified framework for the analysis of deployable trusses using the concentrated strain approach and uses it to provide key insights into the many design decisions to be made in the development of concentrated strain architectures. The framework uses Euler Column Theory to derive closed form solutions to estimate truss performance. The results are compared to a classical solution and shown to give similar results. A range of strut and hinge hierarchy choices are con...

  15. High-Temperature Adhesive Strain Gage Developed

    Pereira, J. Michael; Roberts, Gary D.


    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  16. Relations between microbarograph and strain data

    Mentes, G.; Eper-Pápai, I.


    Abstract The relationship between barometric and strain data related to seasonal characteristics within a year was studied on the basis of parallel records from a quartz tube extensometer and a microbarograph at the Geodynamical Observatory in Sopronbanfalva, Hungary. Both strain and barometric data series were combined into groups according to the three `Lloyd? seasons and they were subjected to spectrum, tidal, regression and coherence analysis. All of the analysis methods establ...

  17. FRP rupture strains in FRP wrapped columns

    Li, Shiqing


    Applying lateral confinement to concrete columns using fibre-reinforced polymer (FRP) composites is a very promising technique. FRP rupture is the typical failure mode of FRP wrapped columns under axial compression. numerous experiments have shown that the FRP rupture strain in an FRP wrapped circular column is significantly lower than the FRP ultimate rupture strain determined from flat coupon test of FRP. Despite a large number of studies on the application of FRP confined columns, the mech...

  18. Conductive lithographic film fabricated resistive strain gauges

    Hay, GI; Evans, PSA; Harrison, DJ; Southee, DJ; Simpson, G; Harrey, PM


    This paper reports progress in sensor fabrication by the conductive lithographic film (CLF) printing process. Work describing strain sensitive structures manufactured using a modified printing process and conductive inks are addressed. The performance of a 'single ink' strain sensitive structure when printed on six alternative polymer substrates (GlossArt, PolyArt, Teslin, Mylar C, Mylar and Kapton) is analysed. Though not intending to compete with conventional gauges in high tolerance measur...

  19. Characterization of lithographically printed resistive strain gauges

    Hay, G.I.; Evans, P.S.A.; Harrison, D J; Southee, D; Simpson, G; Harrey, P.M.


    This paper reports progress in sensor fabrication by the conductive lithographic film (CLF) printing process. Work describing strain-sensitive structures manufactured using a modified printing process and conductive inks is addressed. The performance of a "single-ink" strain-sensitive structure when printed on six alternative substrates (GlossArt, PolyArt, Teslin, Mylar C, Melinex, and Kapton) is analyzed. Though not intending to compete with conventional gauges in high-tolerance measurement,...

  20. Hydraulic Calibrator for Strain-Gauge Balances

    Skelly, Kenneth; Ballard, John


    Instrument for calibrating strain-gauge balances uses hydraulic actuators and load cells. Eliminates effects of nonparallelism, nonperpendicularity, and changes of cable directions upon vector sums of applied forces. Errors due to cable stretching, pulley friction, and weight inaccuracy also eliminated. New instrument rugged and transportable. Set up quickly. Developed to apply known loads to wind-tunnel models with encapsulated strain-gauge balances, also adapted for use in calibrating dynamometers, load sensors on machinery and laboratory instruments.

  1. Strain gauge for high temperature tests

    A strain gauge is described that is intended to measure longitudinal and lateral strains during tubular specimen loading by an axial force and internal pressure at test temperatures up to 1000 K. The use of the gauge for creep study of steel type Kh18N10T at 870 K under complex stress state is given as an example. Experimental data confirm the suitability of the gauge for the purpose mentioned and sufficient accuracy of parameters determined. 3 refs., 3 figs

  2. Laboratory evolution of copper tolerant yeast strains

    Adamo Giusy; Brocca Stefania; Passolunghi Simone; Salvato Benedetto; Lotti Marina


    Abstract Background Yeast strains endowed with robustness towards copper and/or enriched in intracellular Cu might find application in biotechnology processes, among others in the production of functional foods. Moreover, they can contribute to the study of human diseases related to impairments of copper metabolism. In this study, we investigated the molecular and physiological factors that confer copper tolerance to strains of baker's yeasts. Results We characterized the effects elicited in ...

  3. Deformation strain inhomogeneity in columnar grain nickel

    Wu, G.L.; Godfrey, A.; Juul Jensen, D.;


    A method is presented for determination of the local deformation strain of individual grains in the bulk of a columnar grain sample. The method, based on measurement of the change in grain area of each grain, is applied to 12% cold rolled nickel. Large variations are observed in the local strain...... associated with each grain. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved....

  4. Cranial bone morphometric study among mouse strains

    Yamamura Ken-ichi; Kawakami Minoru


    Abstract Background Little is known about the molecular mechanism which regulates how the whole cranium is shaped. Mouse models currently available for genetic research include several hundreds of unique inbred strains and genetically engineered mutants. By cross comparing their genomic structures, we can elucidate the cause of any differences in the phenotype between two strains. The craniometry of subspecies, or closely related species, of mice provide a good systemic model to study the rel...

  5. A tunable strain sensor using nanogranular metals

    Friedemann Völklein; Alexander Kaya; Jens Müller; Pintu Das; Heiko Reith; Fabrizio Porrati; Roland Sachser; Markus Baranowski; Christina Grimm; Schwalb, Christian H.; Michael Huth


    This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. W...

  6. Elastic constants from microscopic strain fluctuations

    Sengupta, Surajit; Nielaba, Peter; Rao, Madan; Binder, K.


    Fluctuations of the instantaneous local Lagrangian strain $\\epsilon_{ij}(\\bf{r},t)$, measured with respect to a static ``reference'' lattice, are used to obtain accurate estimates of the elastic constants of model solids from atomistic computer simulations. The measured strains are systematically coarse- grained by averaging them within subsystems (of size $L_b$) of a system (of total size $L$) in the canonical ensemble. Using a simple finite size scaling theory we predict the behaviour of th...

  7. Elastically Relaxed Free-standing Strained-Si Nanomembranes

    Roberts, Michelle M.; Klein, Levente J.; Savage, Don E.; Slinker, Keith A.; Friesen, Mark; Celler, George; Eriksson, Mark A.; Lagally, Max G.


    Strain plays a critical role in the properties of materials. In silicon and silicon-germanium, strain provides a mechanism for control of both carrier mobility and band offsets. In materials integra-tion, strain is typically tuned through the use of dislocations and elemental composition. We demonstrate a versatile method to control strain, by fabricating membranes in which the final strain state is controlled by elastic strain sharing, i.e., without the formation of defects. We grow Si/SiGe ...

  8. Strain-tunable Josephson current in graphene-superconductor junction

    Wang, Y.; Liu, Y.; Wang, B.


    Strain effects on Josephson current in a graphene-superconductor junction are explored theoretically. It is demonstrated that the supercurrent is an oscillatory function of zigzag direction strain with a strain-dependent oscillating frequency. Interestingly, it is found that the Josephson current under armchair direction strain can be turned on/off with a cutoff strain. In view of the on/off properties of the Josephson current, we propose the strained graphene Josephson junction to be utilized as a supercurrent switch.

  9. Whole Genome Analysis of a Wine Yeast Strain

    Hauser, Nicole C.; Kurt Fellenberg; Rosario Gil; Sonja Bastuck; Hoheisel, Jörg D; Pérez-Ortín, José E.


    Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 an...

  10. The mechanical consequences of load bearing in the equine third metacarpal across speed and gait: the nonuniform distributions of normal strain, shear strain, and strain energy density

    Rubin, Clinton T.; Seeherman, Howard; Qin, Yi-Xian; Gross, Ted S.


    Distributions of normal strain, shear strain, and strain energy density (SED) were determined across the midshaft of the third metacarpal (MCIII, or cannon bone) of 3 adult thoroughbred horses as a function of speed and gait. A complete characterization of the mechanical demands of the bone made through the stride and from mild through the extremes of locomotion was possible by using three 3-element rosette strain gauges bonded at the diaphyseal midshaft of the MCIII and evaluating the strain...

  11. Commonly administered BCG strains including an evolutionarily early strain and evolutionarily late strains of disparate genealogy induce comparable protective immunity against tuberculosis

    Horwitz, Marcus A.; Harth, Günter; Dillon, Barbara Jane; Masleša-Gali, Saša


    BCG has been administered to over 4 billion persons worldwide, but its efficacy in preventing tuberculosis in adults has been highly variable. One hypothesis for its variability is that different strains of BCG vary in protective efficacy, and moreover, that evolutionarily early strains are more efficacious than the more attenuated evolutionarily late strains, which lack region of deletion 2. To examine this hypothesis, we tested six widely used BCG strains – the evolutionarily early strain B...

  12. Differentiation of Mycoplasma gallisepticum Strains through RFLP

    Luis José Carrión


    Full Text Available Avian mycoplasmosis is a disease that considerably affects the poultry sector, which is reflected in the decrease of the production parameters in fertile and commercial egg laying broilers. Presentation costs are so high that it is impossible for the poultry industry to survive without thinking of its effective control or eradication. There is great interest in the type of M. gallisepticum (Mg strains, both vaccine and field, which are key aspects to handle the disease, but there is still no definitive method for Mg strain characterization. Genes related to surface proteins —gapA and mgc2,lipoprotein (lp— that make it possible to identify and characterize the Mg genomically are currently being studied. In this study, regions of the lp gene were amplified from strains F and Ts-11 of Mg through the polymerase chain reaction (PCR technique, which gave an amplicon of 455 bp for each of the strains; each of the amplicons was applied the restriction fragment length polymorphism (RFLP test with the Taq I enzyme, which made it possible to differentiate vaccine strains from field strains obtained from tracheal swab samples taken at commercial farms. It was demonstrated that PCRRFLP is an appropriate method of diagnosis of mycoplasmosis in our environment.

  13. Instrument for measuring fuel cladding strain

    Development work to provide instrumentation for the continuous measurement of strain of material specimens such as nuclear fuel cladding has shown that a microwave sensor and associated instrumentation hold promise. The cylindrical sensor body enclosing the specimen results in a coaxial resonator absorbing microwave energy at frequencies dependent upon the diameter of the specimen. Diametral changes of a microinch can be resolved with use of the instrumentation. Very reasonable values of elastic strain were measured at 750F and 10000F for an internally pressurized 20 percent C.W. 316 stainless steel specimen simulating nuclear fuel cladding. The instrument also indicated the creep strain of the same specimen pressurized at 6500 psi and at a temperature of 10000F for a period of 700 hours. Although the indicated strain appears greater than actual, the sensor/specimen unit experienced considerable oxidation even though an inert gas purge persisted throughout the test duration. By monitoring at least two modes of resonance, the measured strain was shown to be nearly independent of sensor temperature. To prevent oxidation, a second test was performed in which the specimen/sensor units were contained in an evacuated enclosure. The strain of the two prepressurized specimens as indicated by the microwave instrumentation agreed very closely with pre- and post-test measurements obtained with use of a laser interferometer

  14. Strain effect in REBCO coated conductors

    The strain effect on critical current (Ic) in REBCO coated conductors has been intensively investigated owing to its importance for practical applications. The change in Ic with applied strain can be divided into two phenomena; namely reversible variation within elastic deformation for superconducting film, and irreversible degradation related to brittle fracture. REBCO coated conductor is the first material among various high temperature superconductors in which the non-linear reversible change in Ic with uniaxial strain is markedly observed. High stress (strain) tolerance in coated conductors is one of the advantages compared with other superconducting composites, and there are high expectations for application to high-field magnets based on such superior mechanical properties. In this review article, recent research results on the mechanical properties of REBCO coated conductors are summarized, including the stress-strain characteristic for substrate materials, the strain effect on Ic and the experimental techniques for evaluating these properties. Delamination has been recognized as one of the most critical issues for coil applications. Several evaluation methods for delamination strength and interlaminar fracture toughness were introduced. (author)

  15. Strain-displacement relations for strain engineering in single-layer 2d materials

    Midtvedt, Daniel; Lewenkopf, Caio H.; Croy, Alexander


    We investigate the electromechanical coupling in single-layer 2d materials. For non-Bravais lattices, we find important corrections to the standard macroscopic strain-microscopic atomic-displacement theory. We put forward a general and systematic approach to calculate strain-displacement relations for several classes of 2d materials. We apply our findings to graphene as a study case, by combining a tight binding and a valence force-field model to calculate electronic and mechanical properties of graphene nanoribbons under strain. The results show good agreement with the predictions of the Dirac equation coupled to continuum mechanics. For this long wave-limit effective theory, we find that the strain-displacement relations lead to a renormalization correction to the strain-induced pseudo-magnetic fields. A similar renormalization is found for the strain-induced band-gap of black phosphorous. Implications for nanomechanical properties and electromechanical coupling in 2d materials are discussed.

  16. Strain fields adjacent to bone-implant interfaces: strain field analysis using digital image correlation techniques

    Ribeiro, J. E.; Monteiro, J.; Lopes, H.; Vaz, M.A.P.; Guedes, R.M.


    When using conventional surface strain measurement techniques (e.g. strain gauges, dial gauges), the measurement of deformations within cancellous bone is frequently hampered by the material’s highly porous structure and poor mechanical properties. Although detailed strain maps derived from actual experimental data have the potential to resolve many questions concerning the mechanics of cancellous bone, the traditional method of producing maps through measurements with optical techniques has ...

  17. Gendered Responses to Serious Strain: The Argument for a General Strain Theory of Deviance

    Kaufman, Joanne M.


    This paper expands and builds on newer avenues in research on gender and general strain theory (GST). I accomplish this by focusing on serious strains that are relevant for males and females, including externalizing and internalizing forms of negative emotions, and including multiple gendered deviant outcomes. Using the Add Health dataset, I find strong support for the impact of serious strains on both types of negative emotions and different forms of deviance for males and females. However, ...

  18. The influence of strain rate and hydrogen on the plane-strain ductility of Zircaloy cladding

    Link, T.M.; Motta, A.T.; Koss, D.A. [Pennsylvania State Univ., University Park, PA (United States)


    The authors studied the ductility of unirradiated Zircaloy-4 cladding under loading conditions prototypical of those found in reactivity-initiated accidents (RIA), i.e.: near plane-strain deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high strain rates. To conduct these studies, they developed a specimen configuration in which near plane-strain deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit strain at the onset of localized necking and the fracture strain. The experiments indicate that there is little effect of strain rate (10{sup {minus}3} to 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-strain conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture strain but no clear effect on limit strain. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.

  19. True stress-strain curve acquisition for irradiated stainless steel including the range exceeding necking strain

    Kamaya, Masayuki; Kitsunai, Yuji; Koshiishi, Masato


    True stress-strain curves were obtained for irradiated 316L stainless steel by a tensile test and by a curve estimation procedure. In the tensile test, the digital image correlation technique together with iterative finite element analysis was applied in order to identify curves for strain larger than the necking strain. The true stress-strain curves were successfully obtained for the strain of more than 0.4 whereas the necking strain was about 0.2 in the minimum case. The obtained true stress-strain curves were approximated well with the Swift-type equation including the post-necking strain even if the exponential constant n was fixed to 0.5. Then, the true stress-strain curves were estimated by a curve estimation procedure, which was referred to as the K-fit method. Material properties required for the K-fit method were the yield and ultimate strengths or only the yield strength. Some modifications were made for the K-fit method in order to improve estimation accuracy for irradiated stainless steels.

  20. Variation in the strain anisotropy of Zircaloy with temperature and strain

    Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

  1. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan


    This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  2. Strain distribution analysis of sputter-formed strained Si by tip-enhanced Raman spectroscopy

    Hanafusa, H; Hirose, N.; Kasamatsu, A; Mimura, T; Matsui, T; Chong, H.M.H.; Mizuta, H.; Suda, Y.


    Simultaneous nanometer-scale measurements of the strain and surface undulation distributions of strained Si (s-Si) layers on strain-relief quadruple-Si1-xGex-layer buffers, using a combined atomic force microscopy (AFM) and tip-enhanced Raman spectroscopy (TERS) system, clarify that an s-Si sample formed by our previously proposed sputter epitaxy method has a smoother and more uniformly strained surface than an s-Si sample formed by gas-source molecular beam epitaxy. The TERS analyses suggest...

  3. Inexpensive Implementation of Many Strain Gauges

    Berkun, Andrew C.


    It has been proposed to develop arrays of strain gauges as arrays of ordinary metal film resistors and associated electronic readout circuitry on printed circuit boards or other suitable substrates. This proposal is a by-product of a development of instrumentation utilizing metal film resistors on printed-circuit boards to measure temperatures at multiple locations. In the course of that development, it was observed that in addition to being sensitive to temperature, the metal film resistors were also sensitive to strains in the printed-circuit boards to which they were attached. Because of the low cost of ordinary metal film resistors (typically strain gauges, possibly concentrated in small areas. For example, such an array could be designed for use as a computer keyboard with no moving parts, as a device for sensing the shape of an object resting on a surface, or as a device for measuring strains at many points on a mirror, a fuel tank, an airplane wing, or other large object. Ordinarily, the effect of strain on resistance would be regarded as a nuisance in a temperature-measuring application, and the effect of temperature on resistance would be regarded as a nuisance in a strain-measuring application. The strain-induced changes in resistance of the metal film resistors in question are less than those of films in traditional strain gauges. The main novel aspect of present proposal lies in the use of circuitry affording sufficient sensitivity to measure strain plus means for compensating for the effect of temperature. For an array of metal film resistors used as proposed, the readout circuits would include a high-accuracy analog-to-digital converter fed by a low noise current source, amplifier chain, and an analog multiplexer chain. Corrections would be provided by use of high-accuracy calibration resistors and a temperature sensor. By use of such readout circuitry, it would be possible to read the resistances of as many as 100 fixed resistors in a time interval

  4. Anisotropic nature of radially strained metal tubes

    Strickland, Julie N.

    Metal pipes are sometimes swaged by a metal cone to enlarge them, which increases the strain in the material. The amount of strain is important because it affects the burst and collapse strength. Burst strength is the amount of internal pressure that a pipe can withstand before failure, while collapse strength is the amount of external pressure that a pipe can withstand before failure. If the burst or collapse strengths are exceeded, the pipe may fracture, causing critical failure. Such an event could cost the owners and their customers millions of dollars in clean up, repair, and lost time, in addition to the potential environmental damage. Therefore, a reliable way of estimating the burst and collapse strength of strained pipe is desired and valuable. The sponsor currently rates strained pipes using the properties of raw steel, because those properties are easily measured (for example, yield strength). In the past, the engineers assumed that the metal would be work-hardened when swaged, so that yield strength would increase. However, swaging introduces anisotropic strain, which may decrease the yield strength. This study measured the yield strength of strained material in the transverse and axial direction and compared them to raw material, to determine the amount of anisotropy. This information will be used to more accurately determine burst and collapse ratings for strained pipes. More accurate ratings mean safer products, which will minimize risk for the sponsor's customers. Since the strained metal has a higher yield strength than the raw material, using the raw yield strength to calculate burst and collapse ratings is a conservative method. The metal has even higher yield strength after strain aging, which indicates that the stresses are relieved. Even with the 12% anisotropy in the strained and 9% anisotropy in the strain aged specimens, the raw yield strengths are lower and therefore more conservative. I recommend that the sponsor continue using the raw

  5. [Acetobutylic fermentation: strains and regional raw materials].

    Benassi, F O; Bloos, R K; de Rambaldo, L A


    The purpose of the present work was to show, as a first stage, that it is possible to characterize autochtohnous strains of Clostridium acetobutilicum of a good solvent producing capacity, specially N-butanol, through the utilization of suitable techniques for isolating anaerobic microorganisms. Cassava roots were employed as raw material using suitable culture media and an anaerobic jar of cold catalyst. The fermentative capacity of the strains thus isolated was evaluated against a control strain of Clostridium acetobutilicum. Even though some of the strains showed a greater solvent producing power, most of them showed lower fermentation capacity than the control strain, which could be increased, by applying successive thermic treatments. As a second stage, and due to the low cost production of cassava in the Province of Misiones, we studied its utilization as an acetone-butanol fermentation substrate. Mashes composed of binary mixtures of cassava flour and variable amounts of integral flour maize or soy were treated with selected "starters" of Clostridium acetobutilicum, being further processed according to standardized techniques in order to obtain the already mentioned solvents. Mashes concentration influence was also studied using culture media the composition of which proved to be excellent in all experiments carried out under "static system" conditions. The highest fermentative yields (maximum value recorded: 26,20 g of total solvents, with respect to dry solids), were recorded for mashes obtained from mixtures containing integral maize flour; these showed a higher degree of nutrients utilization than those prepared with integral soy flour. PMID:6400763

  6. Strain Echocardiography in Acute Cardiovascular Diseases.

    Favot, Mark; Courage, Cheryl; Ehrman, Robert; Khait, Lyudmila; Levy, Phillip


    Echocardiography has become a critical tool in the evaluation of patients presenting to the emergency department (ED) with acute cardiovascular diseases and undifferentiated cardiopulmonary symptoms. New technological advances allow clinicians to accurately measure left ventricular (LV) strain, a superior marker of LV systolic function compared to traditional measures such as ejection fraction, but most emergency physicians (EPs) are unfamiliar with this method of echocardiographic assessment. This article discusses the application of LV longitudinal strain in the ED and reviews how it has been used in various disease states including acute heart failure, acute coronary syndromes (ACS) and pulmonary embolism. It is important for EPs to understand the utility of technological and software advances in ultrasound and how new methods can build on traditional two-dimensional and Doppler techniques of standard echocardiography. The next step in competency development for EP-performed focused echocardiography is to adopt novel approaches such as strain using speckle-tracking software in the management of patients with acute cardiovascular disease. With the advent of speckle tracking, strain image acquisition and interpretation has become semi-automated making it something that could be routinely added to the sonographic evaluation of patients presenting to the ED with cardiovascular disease. Once strain imaging is adopted by skilled EPs, focused echocardiography can be expanded and more direct, phenotype-driven care may be achievable for ED patients with a variety of conditions including heart failure, ACS and shock. PMID:26823931

  7. Crack initiation under generalized plane strain conditions

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

  8. Multiwalled carbon nanotube film for strain sensing

    We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363 K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications

  9. Methodology to measure strains at high temperatures using electrical strain gages with free filaments

    An experimental methodology used for strains measuring at high temperatures is show in this work. In order to do the measurements, it was used electric strain gages with loose filaments attached to a stainless steel 304 beam with specific cements. The beam has triangular shape and a constant thickness, so the strain is the same along its length. Unless the beam surface be carefully prepared, the strain gage attachment is not efficient. The showed results are for temperatures ranging from 20 deg C to 300 deg C, but the experimental methodology could be used to measure strains at a temperature up to 900 deg C. Analytical calculations based on solid mechanics were used to verify the strain gage electrical installation and the measured strains. At a first moment, beam deformations as a temperature function were plotted. After that, beam deformations with different weighs were plotted as a temperature function. The results shown allowed concluding that the experimental methodology is trustable to measure strains at temperatures up to 300 deg C. (author)

  10. Development of the invar36 thin film strain gauge sensor for strain measurement

    This paper presents development of invar36 thin film strain gauges of various thicknesses ranging from 100 to 1400 Å for strain measurement. The strain gauges are deposited on microslides using the dc magnetron sputtering technique. Resistivity, temperature coefficient of resistance (TCR) and gauge factors of all gauges are measured and compared with each other. TCR is estimated by systematic annealing of gauges in vacuum and found as low as 190 ppm °C−1. A four-point bending setup is designed and fabricated to measure the gauge factors of all gauges. The gauge factor of relatively thinner strain gauge is found as high as 4.5 and for strain gauges with thickness greater than 500 Å gauge factor is found less than 2.5. The variations of gauge resistance with applied strain are studied in terms of linearity, hysteresis and repeatability. The developed strain gauges are connected in a full-bridge configuration and the output response to the applied strain is studied at different excitation voltages. (paper)

  11. Measurement of high temperature strain by the laser-speckle strain gauge

    Yamaguchi, I.


    By using the laser-speckle strain gauge, the strain of metal at the temperature lower than 250 C is measured. The principle of the gauge is to measure the expansion or contraction of the fine structures of surface by detecting the resultant speckle displacement in an optoelectronic way, whereby the effect of rigid-body motion is automatically cancelled out with the aid of a differential detection system. A transportable apparatus was built and a comparison experiment performed with a resistance strain gauge at room temperature. It has a strain sensitivity of .00002, a gauge length smaller than 1 mm, and no upper limit in a range of strain measurement. In the measurement of high-temperature strain it is free from the need for a dummy gauge and insensitive to an electric drift effect. As examples of strain measurement at high-temperature, thermal expansion and contraction of a top of a soldering iron are measured. The interval of the measurement can be made at shortest 1.6 sec. and the change in the strain is clearly followed until the ultimate stationary temperature is reached.

  12. Validation of perceptual strain index to evaluate the thermal strain in experimental hot conditions

    Habibollah Dehghan


    Conclusions: The research findings showed when there is no access to other forms of methods to evaluate the heat stress, it can be used the PeSI in evaluating the strain because of its favorable correlation with the thermal strain.

  13. Characterization of Integrated Optical Strain Sensors Based on Silicon Waveguides

    Westerveld, W.J.; Leinders, S.M.; Muilwijk, P.M.; Pozo, J.


    Microscale strain gauges are widely used in micro electro-mechanical systems (MEMS) to measure strains such as those induced by force, acceleration, pressure or sound. We propose all-optical strain sensors based on micro-ring resonators to be integrated with MEMS. We characterized the strain-induced


    Kobayashi, A.; Takeda, N.; Ogihara, S.; Li, Y.


    Ti-15V-3Cr-3A1-3Sn beta-titanium alloys are subjected to 103/s tensile strain rate by the one bar method to investigate strain rate sensitivity. It is found that the ultimate strength, the total elongation and the absorbed energy, all increase with the increase in strain rate. Dynamical stress-strain curves are also obtained.

  15. Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain

    Oliva-Leyva, M.; Naumis, Gerardo G.


    The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in detail the limiting case of a uniform strain. An effective Dirac Hamiltonian for nonuniform strain is thus reported, which takes into account all strain-induced effects: changes in the nearest-neighbor hopping parameters, the reciprocal lattice deformation and the true shift of the Dirac point. Pseudomagnetic fields are thus explained by means of position-dependent Dirac cones, whereas complex gauge fields appear as a consequence of a position-dependent Fermi velocity. Also, position-dependent Fermi velocity effects on the spinor wavefunction are considered for interesting cases of deformations such as flexural modes.

  16. A new strain gage method for measuring the contractile strain ratio of Zircaloy tubing

    An improved strain gage method for determining the contractile strain ratio (CSR) of Zircaloy tubing was developed. The new method consists of a number of load-unload cyclings at approximately 0.2% plastic strain interval. With this method the CSR of Zircaloy-4 tubing could be determined accurately because it was possible to separate the plastic strains from the elastic strain involvement. The CSR values determined by use of the new method were in good agreement with those calculated from conventional post-test manual measurements. The CSR of the tubing was found to decrease with the amount of deformation during testing because of uneven plastic flow in the gage section. A new technique of inscribing gage marks by use of a YAG laser is discussed. (orig.)

  17. Measurement of local values of strains of the briquette by means of special resistance strain gauges

    Rysz, Jozef


    Local measurement of the coal briquette strains during its destruction caused by sudden decrease of pressure of gas filling pores is difficult, because of high strain of coal (exceeds 16%), which results in bursting. A special type of an resistance-strain gauge, which is pressed into a defined position during briquette preparation was elaborated. This gauge is deformed just as the surrounding coal. The strain is measured as a difference in resistance of a mixture of coal grains (briquette material) and short, 8 micrometers dia. graphite fibers. A ca. 0.5 mm thick and ca. 1 mm long gauge was prepared. Its initial resistance constituted several hundreds ohms. The resistance vs. strain dependence is not linear but stable enough in time and does not depend on the type of gas filling briquette pores (e.g. CO2 and He).

  18. Strain hardening and ductility of iron: axisymmetric vs. plane strain elongation. Technical progress report

    Langford, G.


    The strain hardening of iron at high strains in plane strain elongation (strip drawing) is shown to fall increasngly below that of drawn iron wires at true strains above 2. This makes it unnecessary to invoke shear band formation simultaneously as a strengthening mechanism and as a ductility reducing mechanism in the drawn strip. Rather, shear bands may be a weakening mechanism in all contexts. A set of specimens of interstitial-free iron deformed in three of the four main classifications of deformation symmetry (wire, strip, and chips, representing axisymmetric elongation, plane strain elongation, and pure shear) has been prepared in the form of mechanical test specimens and thin foils for high resolution selected area diffraction. A simple technique for rapid discovery of the <110> axis of foils of strongly textured bcc wire has been worked out.

  19. The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E. coli strains in human urine

    Hancock, Viktoria; Ulett, G.C.; Schembri, M.A.;


    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The...... prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory to...... conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human...

  20. Developments of borehole strain observation outside China

    邱泽华; 石耀霖


    Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It hasbeen used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in research fields of plate tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse andso on. Borehole strainmeter has been improved rapidly and tends to get more and more components included inone probe. Based on observations by this kind of instruments, studies on seismic strain step, slow earthquake,earthquake precursor and volcanic eruption forecasting have made remarkable achievements. In the coming years,borehole strain observation is going to become one major geodetic means, together with GPS and InSAR.

  1. Realization of a Strained Atomic Wire Superlattice.

    Song, Inkyung; Goh, Jung Suk; Lee, Sung-Hoon; Jung, Sung Won; Shin, Jin Sung; Yamane, Hiroyuki; Kosugi, Nobuhiro; Yeom, Han Woong


    A superlattice of strained Au-Si atomic wires is successfully fabricated on a Si surface. Au atoms are known to incorporate into the stepped Si(111) surface to form a Au-Si atomic wire array with both one-dimensional (1D) metallic and antiferromagnetic atomic chains. At a reduced density of Au, we find a regular array of Au-Si wires in alternation with pristine Si nanoterraces. Pristine Si nanoterraces impose a strain on the neighboring Au-Si wires, which modifies both the band structure of metallic chains and the magnetic property of spin chains. This is an ultimate 1D version of a strained-layer superlattice of semiconductors, defining a direction toward the fine engineering of self-assembled atomic-scale wires. PMID:26446292

  2. Influence of nuclear radiation on strain gauges

    The examination of safety of nuclear reactor components requires strain measurements on parts of constructions while operating and this means when influenced by nuclear radiation. As strain gauges are the most applied devices for strain measurement and very suitable in respect to their handling, the influence of nuclear radiation has been investigated for the first time more than 30 years ago in order to obtain information on the reliability of measuring results in such difficult environmental conditions. Since that time only some papers have been published dealing with the progress in this field of measuring technics. A generally valid statement however could not be obtained yet. The effect of 10 MeV electron irradiation on the specific resistivity has been studied. (orig./HP)

  3. Influence of pellet shapes on sheath strains

    In the quest to reduce cladding strain from power ramps and thereby reduce the incidence of fuel defects, various aspects of pellet geometry have been examined experimentally. In parallel, the ELESTRES code has been developed to calculate the expansion and the hourglassing of fuel pellets. This paper presents the predictions of ELESTRES for the influence of pellet shapes on the pellet expansion, and compares them to measurements from two irradiations involving a total of 23 fuel elements. The experiments covered various combinations of pellet lengths, diameters, central holes, chamfer and dishes. The linear heat ratings ranged from 40 to 70 kW/m, with burnups up to 200 MW.h/kgU. The experiments and the predictions show similar trends for strains. Moreover, the predicted strains are generally within the scatter of experimental data. It is concluded that the code is in general agreement with this data

  4. Antimicrobial properties of indigenous Lactobacillus sakei strain

    Vesković-Moračanin Slavica


    Full Text Available The strain I 154 of Lactobacillus sakei has been isolated from traditionally fermented sausages in the course of the realization of the international project (INCO PROJECT No ICA4-CT-2002-10037. This strain exhibited the ability for bacteriocin production. Antimicrobial properties of the isolated bacteriocin (sakacine, its sensibility towards proteolytic enzymes, as well as the effect of increased to high temperatures on its stability have been examined in this work. Semi purified bacteriocin (sakacine has been isolated from bacteriocin - producing strain Lactobacillus sakei I 154 by the method of saturated precipitation with up to 70% ammonium mono-sulphate solution. The activity of isolated sakacine was examined towards Listeria monocytogenes, Staphylococcus aureus and Escherichia coli 0157:H7. Pepsine, Papaine and Proteinase K were used as proteolytic enzymes. The influence of increased and high temperatures on the bacteriocin activity was examined at different temperatures and exposition periods including autoclaving effects.

  5. Surface instabilities during straining of anisotropic materials

    Legarth, Brian Nyvang; Richelsen, Ann Bettina


    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tension...... investigated, it is found that isotropic plasticity can only predict surface instabilities if non-associated plastic flow is accounted for. However, for anisotropic plasticity a surface instability is observed for associated plastic flow if the principal axes of anisotropy coincide with the directions...... of principal overall strain. For other orientations surface instabilities are seen when non-associated plastic flow is taken into account. Compared to tension, smaller compressive deformations are needed in order to initiate a surface instability....

  6. Tensile Properties of TWIP Steel at High Strain Rate

    XIONG Rong-gang; FU Ren-yu; SU Yu; LI Qian; WEI Xi-cheng; LI Lin


    Tensile tests of TWIP steels of two compositions are performed in the strain rate range of 10-5 -103 s-1.Results indicate that steel 1# does not exhibit TWIP effect but deformation-induced martensitic transformation appears only.There exists TWIP effect in steel 3#.Tensile properties at room temperature are sensitive to strain rate in the studied strain rate ranges.Analysis on the relationship between strain-hardening exponent and strain rates shows that strain-induced martensitic transformation and formation of twins during deformation have significant influence on their strain-hardening behavior.

  7. Comparison of barley stripe mosaic virus strains.

    Hafez, Elsayed E; Abdel Aleem, Engy E; Fattouh, Faiza A


    BSMV (barley stripe mosaic virus) particles were obtained in a pure state from infected host plant tissues of Hordeum vulgare. The three genomic parities (alpha, beta and gamma) were amplified by PCR using specific primers for each particle; each was cloned. Partial sequence of the alpha, beta and gamma segments was determined for the Egyptian isolate of barley stripe mosaic virus (BSMV AE1). Alignment of nucleotide sequences with that of other known strains of the virus, BSMV type strains (CV17, ND18 and China), and the generation of phylogenetic trees was performed. A low level of homology was detected comparing 467 bp of the a and 643 bp of the segments to that of the other strains, and thus BSMV alpha and beta segments were in separate clusters. However, 1154 bp of the gamma segments of BSMV AE1 showed a high level of homology especially to strain BSMV ND18, as they both formed a distinct cluster. Northern blotting of pure BSMV AE1 virus and H. vulgare-infected tissue were compared using an alpha ND18 specific probe. Western blotting using antibodies specific for the coat protein (CP) and the triple gene block 1 (TGB1) protein, which are both encoded by the beta ND18 segment, still indicated a high level of similarity between proteins produced by BSMV ND18 and AE1. We suggest that the BSMV AE1 isolate is a distinct strain of BSMV which reflects the genetic evolutionary divergence among BSMV strains and members of the Hordeivirus group. PMID:18533473

  8. Genome sequence of Haemophilus parasuis strain 29755

    Mullins, Michael A.; Register, Karen B.; Bayles, Darrell O; Dyer, David W.; Joanna S Kuehn; Phillips, Gregory J.


    Haemophilus parasuis is a member of the family Pasteurellaceae and is the etiologic agent of Glässer’s disease in pigs, a systemic syndrome associated with only a subset of isolates. The genetic basis for virulence and systemic spread of particular H. parasuis isolates is currently unknown. Strain 29755 is an invasive isolate that has long been used in the study of Glässer’s disease. Accordingly, the genome sequence of strain 29755 is of considerable importance to investigators endeavoring to...

  9. Cells as strain-cued automata

    Cox, Brian N.; Snead, Malcolm L.


    We argue in favor of representing living cells as automata and review demonstrations that autonomous cells can form patterns by responding to local variations in the strain fields that arise from their individual or collective motions. An autonomous cell's response to strain stimuli is assumed to be effected by internally-generated, internally-powered forces, which generally move the cell in directions other than those implied by external energy gradients. Evidence of cells acting as strain-cued automata have been inferred from patterns observed in nature and from experiments conducted in vitro. Simulations that mimic particular cases of pattern forming share the idealization that cells are assumed to pass information among themselves solely via mechanical boundary conditions, i.e., the tractions and displacements present at their membranes. This assumption opens three mechanisms for pattern formation in large cell populations: wavelike behavior, kinematic feedback in cell motility that can lead to sliding and rotational patterns, and directed migration during invasions. Wavelike behavior among ameloblast cells during amelogenesis (the formation of dental enamel) has been inferred from enamel microstructure, while strain waves in populations of epithelial cells have been observed in vitro. One hypothesized kinematic feedback mechanism, "enhanced shear motility", accounts successfully for the spontaneous formation of layered patterns during amelogenesis in the mouse incisor. Directed migration is exemplified by a theory of invader cells that sense and respond to the strains they themselves create in the host population as they invade it: analysis shows that the strain fields contain positional information that could aid the formation of cell network structures, stabilizing the slender geometry of branches and helping govern the frequency of branch bifurcation and branch coalescence (the formation of closed networks). In simulations of pattern formation in

  10. Development of inkjet printed strain sensors

    Correia, V.; Caparros, C.; Casellas, C.; Francesch, L.; Rocha, J. G.; Lanceros-Mendez, S.


    Strain sensors with different architectures, such as single sensors, sensor arrays and a sensor matrix have been developed by inkjet printing technology. Sensors with gauge factors up to 2.48, dimensions of 1.5 mm × 1.8 mm and interdigitated structures with a distance of 30 μm between the finger lines have been achieved based on PeDOT (poly(3,4-ethylenedioxythiophene) and conductive ink. Strain gauges based on silver ink have also been achieved with a gauge factor of 0.35. Performance tests including 1000 mechanical cycles have been successfully carried out for the development of smart prosthesis applications.