Journal articles on the topic 'Strain engineering efforts'
To see the other types of publications on this topic, follow the link: Strain engineering efforts.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Strain engineering efforts.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Dang, Chaoqun, Anliang Lu, Heyi Wang, Hongti Zhang, and Yang Lu. "Diamond semiconductor and elastic strain engineering." Journal of Semiconductors 43, no. 2 (February 1, 2022): 021801. http://dx.doi.org/10.1088/1674-4926/43/2/021801.
Full textAbstract:
Abstract Diamond, as an ultra-wide bandgap semiconductor, has become a promising candidate for next-generation microelectronics and optoelectronics due to its numerous advantages over conventional semiconductors, including ultrahigh carrier mobility and thermal conductivity, low thermal expansion coefficient, and ultra-high breakdown voltage, etc. Despite these extraordinary properties, diamond also faces various challenges before being practically used in the semiconductor industry. This review begins with a brief summary of previous efforts to model and construct diamond-based high-voltage switching diodes, high-power/high-frequency field-effect transistors, MEMS/NEMS, and devices operating at high temperatures. Following that, we will discuss recent developments to address scalable diamond device applications, emphasizing the synthesis of large-area, high-quality CVD diamond films and difficulties in diamond doping. Lastly, we show potential solutions to modulate diamond’s electronic properties by the “elastic strain engineering” strategy, which sheds light on the future development of diamond-based electronics, photonics and quantum systems.
2
Ratnaparkhe, Supriya, and Milind B. Ratnaparkhe. "Advances in Strain Engineering for Improved Bio-fuel Production- a Perspective." Current Metabolomics and Systems Biology 7, no. 1 (September 6, 2020): 1–5. http://dx.doi.org/10.2174/2213235x07999190528085552.
Full textAbstract:
Bio-fuels are ecologically sustainable alternates of fossil fuel and have attracted interest of research community in the last few decades. Microorganisms such as bacteria, fungi and microalgae have important roles to play at various steps of bio-fuel production. And therefore several efforts such as genetic engineering have been made to improve the performance of these microbes to achieve the desired results. Metabolic engineering of organisms has benefitted immensely from the novel tools and technologies that have recently been developed. Microorganisms have the advantage of smaller and less complex genome and hence are best suitable for genetic manipulations. In this perspective, we briefly review a few interesting studies which represent some recent advances in the field of metabolic engineering of microbes.
3
Leem, Juyoung. "A snapshot review on exciton engineering in deformed 2D materials." MRS Advances 5, no. 64 (2020): 3491–506. http://dx.doi.org/10.1557/adv.2020.350.
Full textAbstract:
AbstractMost optoelectronic characteristics of two-dimensional (2D) materials are associated with excitonic effects. Excitonic effects in 2D material have been intensively investigated, and various efforts to engineer exciton behavior in 2D materials have been reported for advanced nanophotonic and optoelectronic applications. Excitons in 2D semiconductors can be controlled by external stimuli, including mechanical, electrical, thermal, and magnetic stimuli. Mechanical stimuli applied to a 2D material can generate uniform or non-uniform deformation and strain gradient in the 2D lattice, which creates a strain-induced bandgap energy gradient in the 2D material. In an inhomogeneous bandgap energy gradient generated by a non-uniform strain gradient, excitons drift across the energy gradient. Exciton engineering in deformed 2D materials aims to control exciton movement by mechanical strain. In this snapshot review, we focus on exciton engineering in a mechanically deformed 2D material and their potential towards advanced optoelectronic and photonic applications.
4
Zhang, Yu, Tsan-Yu Chiu, Jin-Tao Zhang, Shu-Jie Wang, Shu-Wen Wang, Long-Ying Liu, Zhi Ping, et al. "Systematical Engineering of Synthetic Yeast for Enhanced Production of Lycopene." Bioengineering 8, no. 1 (January 19, 2021): 14. http://dx.doi.org/10.3390/bioengineering8010014.
Full textAbstract:
Synthetic biology allows the re-engineering of biological systems and promotes the development of bioengineering to a whole new level, showing great potential in biomanufacturing. Here, in order to make the heterologous lycopene biosynthesis pathway compatible with the host strain YSy 200, we evolved YSy200 using a unique Synthetic Chromosome Rearrangement and Modification by LoxP-mediated Evolution (SCRaMbLE) system that is built in the Sc2.0 synthetic yeast. By inducing SCRaMbLE, we successfully identified a host strain YSy201 that can be served as a suitable host to maintain the heterologous lycopene biosynthesis pathway. Then, we optimized the lycopene biosynthesis pathway and further integrated into the rDNA arrays of YSy201 to increase its copy number. In combination with culturing condition optimization, we successfully screened out the final yeast strain YSy222, which showed a 129.5-fold increase of lycopene yield in comparison with its parental strain. Our work shows that, the strategy of combining the engineering efforts on both the lycopene biosynthesis pathway and the host strain can improve the compatibility between the heterologous pathway and the host strain, which can further effectively increase the yield of the target product.
5
Corley-Lay, Judith B. "Efforts by North Carolina Department of Transportation to Develop Mechanistic Pavement Design System." Transportation Research Record: Journal of the Transportation Research Board 1539, no. 1 (January 1996): 18–24. http://dx.doi.org/10.1177/0361198196153900103.
Full textAbstract:
A first generation mechanistic empirical pavement design procedure was developed using falling weight deflectometer deflections taken over a 3-year period at 16 test sections in Siler City, North Carolina. Information available for use in developing the procedure included deflection data, surface and air temperature, coring thicknesses at each test location, pavement performance records regarding rate of cracking, and traffic records. Jung's method, based on the curvature of the deflection bowl, was used to calculate strain at the bottom of the asphalt layer as a measure of fatigue. This calculated strain was used to obtain a calculated number of load repetitions to failure. Comparision of actual loads to failure with calculated loads to failure resulted in a table of shift factors by pavement type.
6
Nah, Ji-Hye, Hye-Jin Kim, Han-Na Lee, Mi-Jin Lee, Si-Sun Choi, and Eung-Soo Kim. "Identification and Biotechnological Application of Novel Regulatory Genes Involved inStreptomycesPolyketide Overproduction through Reverse Engineering Strategy." BioMed Research International 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/549737.
Full textAbstract:
Polyketide belongs to a family of abundant natural products typically produced by the filamentous soil bacteriaStreptomyces. Similar to the biosynthesis of most secondary metabolites produced in theStreptomycesspecies, polyketide compounds are synthesized through tight regulatory networks in the cell, and thus extremely low levels of polyketides are typically observed in wild-type strains. Although manyStreptomycespolyketides and their derivatives have potential to be used as clinically important pharmaceutical drugs, traditional strain improvement strategies such as random recursive mutagenesis have long been practiced with little understanding of the molecular basis underlying enhanced polyketide production. Recently, identifying, understanding, and applying a novel polyketide regulatory system identified from various Omics approaches, has become an important tool for rationalStreptomycesstrain improvement. In this paper, DNA microarray-driven reverse engineering efforts for improving titers of polyketides are briefly summarized, primarily focusing on our recent results of identification and application of novel global regulatory genes such aswblA, SCO1712, and SCO5426 inStreptomycesspecies. Sequential targeted gene manipulation involved in polyketide biosynthetic reguation synergistically provided an efficient and rational strategy forStreptomycesstrain improvement. Moreover, the engineered regulation-optimizedStreptomycesmutant strain was further used as a surrogate host for heterologous expression of polyketide pathway.
7
Xu, Xin, Chengtuo Niu, Chunfeng Liu, Jinjing Wang, Feiyun Zheng, and Qi Li. "A Novel Approach to Develop Lager Yeast with Higher NADH Availability to Improve the Flavor Stability of Industrial Beer." Foods 10, no. 12 (December 8, 2021): 3057. http://dx.doi.org/10.3390/foods10123057.
Full textAbstract:
Flavor stability is important for beer quality and extensive efforts have been undertaken to improve this. In our previous work, we proved a concept whereby metabolic engineering lager yeast with increased cellular nicotinamide adenine dinucleotide hydride (NADH) availability could enhance the flavor stability of beer. However, the method for breeding non-genetically modified strains with higher NADH levels remains unsolved. In the current study, we reported a novel approach to develop such strains based on atmospheric and room temperature plasma (ARTP) mutagenesis coupled with 2,4-dinitrophenol (DNP) selection. As a result, we obtained a serial of strains with higher NADH levels as well as improved flavor stability. For screening an optimal strain with industrial application potential, we examined the other fermentation characteristics of the mutants and ultimately obtained the optimal strain, YDR-63. The overall fermentation performance of the strain YDR-63 in pilot-scale fermentation was similar to that of the parental strain YJ-002, but the acetaldehyde production was decreased by 53.7% and the resistance staling value of beer was improved by 99.8%. The forced beer aging assay further demonstrated that the favor stability was indeed improved as the contents of 5-hydroxymethylfurfural in YDR-63 was less than that in YJ-002 and the sensory notes of staling was weaker in YDR-63. We also employed this novel approach to another industrial strain, M14, and succeeded in improving its flavor stability. All the findings demonstrated the efficiency and versatility of this new approach in developing strains with improved flavor stability for the beer industry.
8
Panke, Sven. "Taming the Beast of Biology: Synthetic Biology and Biological Systems Engineering." CHIMIA International Journal for Chemistry 74, no. 5 (May 27, 2020): 402–6. http://dx.doi.org/10.2533/chimia.2020.402.
Full textAbstract:
Despite the availability of a variety of ' -omics ' technologies to support the system-wide analysis of industrially relevant microorganisms, the manipulation of strains towards an economically relevant goal remains a challenge. Remarkably, our ability to catalogue the participants in and model ever more comprehensive aspects of a microorganism's physiology is now complemented by technologies that permanently expand the scope of engineering interventions that can be imagined. In fact, genome-wide editing and re-synthesis of microbial and even eukaryotic chromosomes have become widely applied methods. At the heart of this emerging system-wide engineering approach, often labelled ' Synthetic Biology ' , is the continuous improvement of large-scale DNA synthesis, which is put to two-fold use: (i) starting ever more ambitious efforts to re-write existing and coding novel molecular systems, and (ii) designing and constructing increasingly sophisticated library technologies, which has led to a renaissance of directed evolution in strain engineering. Here, we briefly review some of the critical concepts and technological stepping-stones of Synthetic Biology on its way to becoming a mature industrial technology.
9
Gurusamy, Muralimohan, and Balkrishna C. Rao. "A Comprehensive Review of Large-Strain-Extrusion Machining Process for Production of Fine-Grained Materials." Crystals 13, no. 1 (January 11, 2023): 131. http://dx.doi.org/10.3390/cryst13010131.
Full textAbstract:
Bulk nanostructured metals and alloys are finding increasing structural applications due to their superior mechanical properties. The methods that rely on the severe plastic deformation technique for effecting microstructural refinement through imposing large strains are utilized mostly to produce nanostructured materials. The machining process has been demonstrated as a simple process for severe plastic deformation by imposing large strains through a single pass of the cutting tool where strains in a range of 1–15 can be imposed for a variety of materials by varying the cutting conditions and tool geometry. However, the geometry of the resulting chip subjected to severe plastic deformation during the machining process is not under control and, hence, a variant of the machining process, called the large-strain-extrusion machining process, has been proposed and utilized extensively for producing bulk nanostructured materials. Large-strain-extrusion machining possesses simultaneous control over microstructure refinement, through managing the strain during large-strain machining, and the shape and dimension of the resulting chip by the extrusion process. This study provides a comprehensive review of the large-strain-extrusion machining process by presenting the findings related to the utilization of this process for the production of fine-grained foils for various metals and alloys. Further research efforts related to finite-element modelling of large-strain-extrusion machining and their usefulness in designing the experimental setup and process conditions are also discussed.
10
Bushman, Mary, and Rustom Antia. "A general framework for modelling the impact of co-infections on pathogen evolution." Journal of The Royal Society Interface 16, no. 155 (June 2019): 20190165. http://dx.doi.org/10.1098/rsif.2019.0165.
Full textAbstract:
Theoretical models suggest that mixed-strain infections, or co-infections, are an important driver of pathogen evolution. However, the within-host dynamics of co-infections vary enormously, which complicates efforts to develop a general understanding of how co-infections affect evolution. Here, we develop a general framework which condenses the within-host dynamics of co-infections into a few key outcomes, the most important of which is the overall R 0 of the co-infection. Similar to how fitness is determined by two different alleles in a heterozygote, the R 0 of a co-infection is a product of the R 0 values of the co-infecting strains, shaped by the interaction of those strains at the within-host level. Extending the analogy, we propose that the overall R 0 reflects the dominance of the co-infecting strains, and that the ability of a mutant strain to invade a population is a function of its dominance in co-infections. To illustrate the utility of these concepts, we use a within-host model to show how dominance arises from the within-host dynamics of a co-infection, and then use an epidemiological model to demonstrate that dominance is a robust predictor of the ability of a mutant strain to save a maladapted wild-type strain from extinction (evolutionary emergence).
11
Marasteanu, Mihai O., Timothy Clyne, Jim McGraw, Xinjun Li, and Raul Velasquez. "High-Temperature Rheological Properties of Asphalt Binders." Transportation Research Record: Journal of the Transportation Research Board 1901, no. 1 (January 2005): 52–59. http://dx.doi.org/10.1177/0361198105190100107.
Full textAbstract:
Previous research efforts have shown that the rutting parameter used in the performance grade asphalt binder specifications, | G*|/ sin d, does not reasonably predict the rutting potential of asphalt mixtures, especially when modified binders are used. A number of other parameters, such as the zero shear rate viscosity and the permanent strain accumulated under repeated creep and recovery, were investigated; however, no consensus was achieved. This paper investigates the use of zero shear rate viscosity and of repeated creep permanent strain as potential specification parameters and discusses the importance of temperature susceptibility and of strain tolerance to the rut resistance of asphalt binders.
12
Al-Khairy, Dina, Weiqi Fu, Amnah Salem Alzahmi, Jean-Claude Twizere, Shady A. Amin, Kourosh Salehi-Ashtiani, and Alexandra Mystikou. "Closing the Gap between Bio-Based and Petroleum-Based Plastic through Bioengineering." Microorganisms 10, no. 12 (November 23, 2022): 2320. http://dx.doi.org/10.3390/microorganisms10122320.
Full textAbstract:
Bioplastics, which are plastic materials produced from renewable bio-based feedstocks, have been investigated for their potential as an attractive alternative to petroleum-based plastics. Despite the harmful effects of plastic accumulation in the environment, bioplastic production is still underdeveloped. Recent advances in strain development, genome sequencing, and editing technologies have accelerated research efforts toward bioplastic production and helped to advance its goal of replacing conventional plastics. In this review, we highlight bioengineering approaches, new advancements, and related challenges in the bioproduction and biodegradation of plastics. We cover different types of polymers, including polylactic acid (PLA) and polyhydroxyalkanoates (PHAs and PHBs) produced by bacterial, microalgal, and plant species naturally as well as through genetic engineering. Moreover, we provide detailed information on pathways that produce PHAs and PHBs in bacteria. Lastly, we present the prospect of using large-scale genome engineering to enhance strains and develop microalgae as a sustainable production platform.
13
Voyiadjis, GZ, AN Palazotto, and X.-L. Gao. "Modeling of metallic materials at high strain rates with continuum damage mechanics." Applied Mechanics Reviews 55, no. 5 (September 1, 2002): 481–93. http://dx.doi.org/10.1115/1.1495522.
Full textAbstract:
Abstract Damage modeling of metallic materials under high strain rate loading conditions is reviewed. The emphasis is on the modeling efforts based on continuum damage mechanics, although many important references dealing with general aspects of dynamic behavior of materials are also discussed. Relevant issues on the use of continuum damage mechanics and on the damage modeling of composites are addressed as well. This review article deals with 134 references
14
Shelke, Prof Mayur, Gaurav Ingole, Purushottam Shende, Rajan Masurkar, Khushi Dhengre, Paresh Girhepunje, and Abhijeet Dwivedi. "Analysis of Electric Go Kart." International Journal for Research in Applied Science and Engineering Technology 10, no. 2 (February 28, 2022): 216–19. http://dx.doi.org/10.22214/ijraset.2022.40218.
Full textAbstract:
Abstract: The Electric Go-Karts use a knuckle as a significant a half of their steering systems, it controls the efforts applied further because the turning capacities. we tend to tend to area unit proposing modification within the materials used which can increase the strength of the knuckle. The recent technologies developed helps in reducing the strain and strains while not poignant the physical properties. at intervals the gift work we've got used SOLIDWORKS computer code for analysis of knuckle joints with varied materials and ranging hundreds. Steering knuckle plays a significant role during a vehicle linking the steering mechanism, wheel hub and brakes tothe vehicle body
15
Qi, Qungang, Ming Hao, Wing-on Ng, Steven C. Slater, Susan R. Baszis, James D. Weiss, and Henry E. Valentin. "Application of the Synechococcus nirA Promoter To Establish an Inducible Expression System for Engineering the Synechocystis Tocopherol Pathway." Applied and Environmental Microbiology 71, no. 10 (October 2005): 5678–84. http://dx.doi.org/10.1128/aem.71.10.5678-5684.2005.
Full textAbstract:
ABSTRACT Tocopherols are important antioxidants in lipophilic environments. They are synthesized by plants and some photosynthetic bacteria. Recent efforts to analyze and engineer tocopherol biosynthesis led to the identification of Synechocystis sp. strain PCC 6803 as a well-characterized model system. To facilitate the identification of the rate-limiting step(s) in the tocopherol biosynthetic pathway through the modulation of transgene expression, we established an inducible expression system in Synechocystis sp. strain PCC 6803. The nirA promoter from Synechococcus sp. strain PCC 7942, which is repressed by ammonium and induced by nitrite (S.-I. Maeda et al., J. Bacteriol. 180:4080-4088, 1998), was chosen to drive the expression of Arabidopsis thaliana p-hydroxyphenylpyruvate dioxygenase. The enzyme catalyzes the formation of homogentisic acid from p-hydroxyphenylpyruvate. Expression of this gene under inducing conditions resulted in up to a fivefold increase in total tocopherol levels with up to 20% of tocopherols being accumulated as tocotrienols. The culture supernatant of these cultures exhibited a brown coloration, a finding indicative of homogentisic acid excretion. Enzyme assays, functional complementation, reverse transcription-PCR, and Western blot analysis confirmed transgene expression under inducing conditions only. These data demonstrate that the nirA promoter can be used to control transgene expression in Synechocystis and that homogentisic acid is a limiting factor for tocopherol synthesis in Synechocystis sp. strain PCC 6803.
16
Cheng, Jin, and Y. Lawrence Yao. "Process Design of Laser Forming for Three-Dimensional Thin Plates." Journal of Manufacturing Science and Engineering 126, no. 2 (May 1, 2004): 217–25. http://dx.doi.org/10.1115/1.1751187.
Full textAbstract:
Extensive efforts have been made in analyzing and predicting laser forming processes of sheet metal. Process design, on the other hand, is concerned with determination of laser scanning paths and laser heat condition given a desired shape. This paper presents an approach for process design of laser forming of thin plates with doubly curved shapes. The important feature of this method is that it first calculates the strain field required to form the shape. Scanning paths are decided based on the concept of in-plane strain, bending strain, principal minimal strain and temperature gradient mechanism of laser forming. Heating condition is determined by a lumped method. Effectiveness of the approach is numerically and experimentally validated through two different doubly curved shapes.
17
Lennen, Rebecca M., Max A. Kruziki, Kritika Kumar, Robert A. Zinkel, Kristin E. Burnum, Mary S. Lipton, Spencer W. Hoover, et al. "Membrane Stresses Induced by Overproduction of Free Fatty Acids in Escherichia coli." Applied and Environmental Microbiology 77, no. 22 (September 23, 2011): 8114–28. http://dx.doi.org/10.1128/aem.05421-11.
Full textAbstract:
ABSTRACTMicrobially produced fatty acids are potential precursors to high-energy-density biofuels, including alkanes and alkyl ethyl esters, by either catalytic conversion of free fatty acids (FFAs) or enzymatic conversion of acyl-acyl carrier protein or acyl-coenzyme A intermediates. Metabolic engineering efforts aimed at overproducing FFAs inEscherichia colihave achieved less than 30% of the maximum theoretical yield on the supplied carbon source. In this work, the viability, morphology, transcript levels, and protein levels of a strain ofE. colithat overproduces medium-chain-length FFAs was compared to an engineered control strain. By early stationary phase, an 85% reduction in viable cell counts and exacerbated loss of inner membrane integrity were observed in the FFA-overproducing strain. These effects were enhanced in strains endogenously producing FFAs compared to strains exposed to exogenously fed FFAs. Under two sets of cultivation conditions, long-chain unsaturated fatty acid content greatly increased, and the expression of genes and proteins required for unsaturated fatty acid biosynthesis were significantly decreased. Membrane stresses were further implicated by increased expression of genes and proteins of the phage shock response, the MarA/Rob/SoxS regulon, and thenuoandcyooperons of aerobic respiration. Gene deletion studies confirmed the importance of the phage shock proteins and Rob for maintaining cell viability; however, little to no change in FFA titer was observed after 24 h of cultivation. The results of this study serve as a baseline for future targeted attempts to improve FFA yields and titers inE. coli.
18
Barthes, Julien, Hayriye Özçelik, Mathilde Hindié, Albana Ndreu-Halili, Anwarul Hasan, and Nihal Engin Vrana. "Cell Microenvironment Engineering and Monitoring for Tissue Engineering and Regenerative Medicine: The Recent Advances." BioMed Research International 2014 (2014): 1–18. http://dx.doi.org/10.1155/2014/921905.
Full textAbstract:
In tissue engineering and regenerative medicine, the conditions in the immediate vicinity of the cells have a direct effect on cells’ behaviour and subsequently on clinical outcomes. Physical, chemical, and biological control of cell microenvironment are of crucial importance for the ability to direct and control cell behaviour in 3-dimensional tissue engineering scaffolds spatially and temporally. In this review, we will focus on the different aspects of cell microenvironment such as surface micro-, nanotopography, extracellular matrix composition and distribution, controlled release of soluble factors, and mechanical stress/strain conditions and how these aspects and their interactions can be used to achieve a higher degree of control over cellular activities. The effect of these parameters on the cellular behaviour within tissue engineering context is discussed and how these parameters are used to develop engineered tissues is elaborated. Also, recent techniques developed for the monitoring of the cell microenvironmentin vitroandin vivoare reviewed, together with recent tissue engineering applications where the control of cell microenvironment has been exploited. Cell microenvironment engineering and monitoring are crucial parts of tissue engineering efforts and systems which utilize different components of the cell microenvironment simultaneously can provide more functional engineered tissues in the near future.
19
Shawki, T. G. "The Phenomenon of Shear Strain Localization in Dynamic Viscoplasticity." Applied Mechanics Reviews 45, no. 3S (March 1, 1992): S46—S61. http://dx.doi.org/10.1115/1.3121391.
Full textAbstract:
This article addresses shear flow localization during high rates of deformation of thermal viscoplastic materials. An overview of several efforts towards an improved understanding of shear band formation is given. This paper aims at extracting a unified framework towards the analysis of shear band formation for the considered class of deformations. For this purpose, we present a number of rigorous exact solutions for the one–dimensional simple shearing deformation of a general class of thermal viscoplastic material response. These solutions are used as benchmarks for the validation of both analytical and computational procedures. The interactive roles of inertia, rate–sensitivity, heat conduction, perturbation geometry, boundary conditions, thermal softening, strain hardening and constitutive description as regards the initiation and further intensification of flow localization are thoroughly addressed. We also examine the delicate questions concerning the notion of shear localization and the related mathematical characterization, length and time scales as well as the connection between localization and catastrophic failure.
20
Wang, Haiyang, and M. E. Barkey. "Strain Space Formulation of the Armstrong-Frederick Family of Plasticity Models." Journal of Engineering Materials and Technology 120, no. 3 (July 1, 1998): 230–35. http://dx.doi.org/10.1115/1.2812348.
Full textAbstract:
Strain space based plasticity models have certain advantages in theoretical development and numerical implementation. Previous efforts have been made to formulate cyclic plasticity models in strain space using the idea of multiple-yield surface theory. Recently, however, Armstrong-Frederick type plasticity models have received increasingly more attention because of their enhanced performance in predicting ratchetting behavior. In this paper, the strain space formulation of the Armstrong-Frederick family of cyclic plasticity models is established, and several representative strain controlled loading paths are used to compare the results from the proposed formulation and previous experimental data. The excellent agreement suggests the proposed strain space formulation is very promising in strain controlled cyclic plasticity such as finite element analysis, strain gage rosette applications, and multiaxial notch analysis using pseudo-stress or pseudo-strain approaches.
21
Jan, M. M., H.-P. Gaenser, and W. Eichlseder. "Prediction of the low cycle fatigue regime of the S–N curve with application to an aluminium alloy." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 5 (October 6, 2011): 1198–209. http://dx.doi.org/10.1177/0954406211422146.
Full textAbstract:
Engineering estimates for the prediction of fatigue life is an important consideration at the design stage of components. Conventional approach of dimensioning against cyclic loading consists of comparing the stress amplitudes against the life time. Similarly, when a component is under high loading, a strain-life methodology is adopted. In both cases, extensive experimental efforts are required for obtaining the stress-life or strain-life curves. Therefore, it is important to develop a methodology for obtaining the fatigue life of a material to obtain a basic fatigue life data for design engineers. This study focuses on the fatigue life of a material in the region of low cycle fatigue. A method is proposed for obtaining an estimate for the fatigue life of material under high loading from the results of the high cycle fatigue and static properties of the material within the stress-based diagram. The concept is applied to a wrought aluminium alloy typically used for cryogenic applications.
22
Zhang, Chun-Yi, Cheng Lu, Cheng-Wei Fei, Ling-Jun Liu, Yat-Sze Choy, and Xiang-Guo Su. "Multiobject Reliability Analysis of Turbine Blisk with Multidiscipline under Multiphysical Field Interaction." Advances in Materials Science and Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/649046.
Full textAbstract:
To study accurately the influence of the deformation, stress, and strain of turbine blisk on the performance of aeroengine, the comprehensive reliability analysis of turbine blisk with multiple disciplines and multiple objects was performed based on multiple response surface method (MRSM) and fluid-thermal-solid coupling technique. Firstly, the basic thought of MRSM was introduced. And then the mathematical model of MRSM was established with quadratic polynomial. Finally, the multiple reliability analyses of deformation, stress, and strain of turbine blisk were completed under multiphysical field coupling by the MRSM, and the comprehensive performance of turbine blisk was evaluated. From the reliability analysis, it is demonstrated that the reliability degrees of the deformation, stress, and strain for turbine blisk are 0.9942, 0.9935, 0.9954, and 0.9919, respectively, when the allowable deformation, stress, and strain are 3.7 × 10−3 m, 1.07 × 109 Pa, and 1.12 × 10−2 m/m, respectively; besides, the comprehensive reliability degree of turbine blisk is 0.9919, which basically satisfies the engineering requirement of aeroengine. The efforts of this paper provide a promising approach method for multidiscipline multiobject reliability analysis.
23
Hecht, J., S. Pinto, and Manfred Geiger. "Determination of Mechanical Properties for the Hydroforming of Magnesium Sheets at Elevated Temperature." Advanced Materials Research 6-8 (May 2005): 779–86. http://dx.doi.org/10.4028/www.scientific.net/amr.6-8.779.
Full textAbstract:
Thanks to the low weight, magnesium alloys feature high specific strength and stiffness properties. Thus they prove to be promising materials for todays ambitious automotive light weight construction efforts. Due to their comparative low formability at room temperature the process of magnesium sheet hydroforming can be improved at temperatures higher than 200 °C by the activation of additional sliding planes. This paper illustrates the determination of mechanical properties for the hydroforming of magnesium sheets at elevated temperature. In particular the mechanical behavior at elevated temperature was investigated by means of the tensile test and of the hydraulic bulge test. For the determination of the strains an optical measurement system was introduced into the experimental set-up. The exact knowledge of the strain condition in the area of diffuse necking enabled the determination of the flow curve in the tensile test also beyond the uniform elongation. The influence of temperature and strain rate was analyzed as well as the influence of uni- and biaxial stress state on the flow curve. Using circular and elliptic dies with different aspect ratio the hydraulic bulge test served to determinate the forming limit curves at three different elevated temperatures.
24
Wannier, Timothy M., Aditya M. Kunjapur, Daniel P. Rice, Michael J. McDonald, Michael M. Desai, and George M. Church. "Adaptive evolution of genomically recodedEscherichia coli." Proceedings of the National Academy of Sciences 115, no. 12 (February 13, 2018): 3090–95. http://dx.doi.org/10.1073/pnas.1715530115.
Full textAbstract:
Efforts are underway to construct several recoded genomes anticipated to exhibit multivirus resistance, enhanced nonstandard amino acid (nsAA) incorporation, and capability for synthetic biocontainment. Although our laboratory pioneered the first genomically recoded organism (Escherichia colistrain C321.∆A), its fitness is far lower than that of its nonrecoded ancestor, particularly in defined media. This fitness deficit severely limits its utility for nsAA-linked applications requiring defined media, such as live cell imaging, metabolic engineering, and industrial-scale protein production. Here, we report adaptive evolution of C321.∆A for more than 1,000 generations in independent replicate populations grown in glucose minimal media. Evolved recoded populations significantly exceeded the growth rates of both the ancestral C321.∆A and nonrecoded strains. We used next-generation sequencing to identify genes mutated in multiple independent populations, and we reconstructed individual alleles in ancestral strains via multiplex automatable genome engineering (MAGE) to quantify their effects on fitness. Several selective mutations occurred only in recoded evolved populations, some of which are associated with altering the translation apparatus in response to recoding, whereas others are not apparently associated with recoding, but instead correct for off-target mutations that occurred during initial genome engineering. This report demonstrates that laboratory evolution can be applied after engineering of recoded genomes to streamline fitness recovery compared with application of additional targeted engineering strategies that may introduce further unintended mutations. In doing so, we provide the most comprehensive insight to date into the physiology of the commonly used C321.∆A strain.
25
Lytvyniak, Oksana. "DEFORMATION ANALYSIS OF LAYERED REINFORCED CONCRETE - FOAM CONCRETE FLOOR SLABS." Acta Polytechnica 60, no. 4 (September 1, 2020): 324–37. http://dx.doi.org/10.14311/ap.2020.60.0324.
Full textAbstract:
This article presents a theoretical study of a stress-strain state of layered reinforced concrete - foam concrete floor slabs (hereinafter called as the LRFCS), with the use of a deformation analysis. Compressive and tensile diagrams of the foam concrete, a tensile diagram of the reinforced concrete and compressive and tensile diagrams of the reinforcement rod are used for the estimation of the stress-strain state of the calculated cross-section of the LRFCS. It should be noted that this article presents the deformation method of loading by the scheme of pure bending for the LRFCS. This deformation method of loading is determined by six shapes of the stress-strain state. These shapes of the stress-strain state are represented by the corresponding distribution diagrams of the relative deformations and the distribution diagrams of internal stresses in the calculated cross-section of the floor slab. Also, this article presents the corresponding equilibrium equations of internal efforts and moments, which act in the calculated cross-section of the floor slab for all shapes of its stress-strain state. Consequently, the mentioned recommendations and mathematical dependencies allow to evaluate the stress-strain state of the LRFCS from its initial loading to its destruction.
26
Campoccia, Davide, Lucio Montanaro, and Carla Renata Arciola. "Current Methods for Molecular Epidemiology Studies of Implant Infections." International Journal of Artificial Organs 32, no. 9 (September 2009): 642–54. http://dx.doi.org/10.1177/039139880903200914.
Full textAbstract:
Over the last few decades, the number of surgical procedures involving prosthetic materials has greatly multiplied, along with the rising medical and economic impact of implant-associated infections. The need to appropriately counteract and deal with this phenomenon has led to growing efforts to elucidate the etiology, pathogenesis and epidemiology of these types of infections, characterized by opportunistic pathogens. Molecular epidemiology studies have progressively emerged as a leading multitask tool to identify and fingerprint bacterial strains, unveil the complex clonal nature of important pathogens, detect outbreak events, track the origin of the infections, assess the clinical significance of individual strain types, survey their distribution, recognize associations of strain types with specific virulence determinants and/or pathological conditions, assess the role played by the specific components of the virulon, and reveal the phylogeny and the mechanisms through which new strain types have emerged. Despite the many advances that have been made thanks to these flourishing new approaches to molecular epidemiology, a number of critical aspects remain challenging. In this paper, we briefly discuss the current limitations and possible developments of molecular epidemiology methods in the investigation and surveillance of implant infections.
27
Abeyarartne, Rohan. "Dynamic Phase Transitions in a One-Dimensional Elastic Continuum." Applied Mechanics Reviews 43, no. 5S (May 1, 1990): S186—S188. http://dx.doi.org/10.1115/1.3120801.
Full textAbstract:
This paper summarizes the results of some recent investigations on the continuum mechanical modeling of thermo-elastic phase transitions in solids carried out jointly with J. K. Knowles. Our most recent efforts have been focussed on the role of a kinetic law and an initiation criterion in modeling dynamic phase transitions, and their relationship to theories that include viscosity and strain-gradient effects.
28
Tian, T., T. Zhang, Y. Lin, and X. Cai. "Vascularization in Craniofacial Bone Tissue Engineering." Journal of Dental Research 97, no. 9 (April 2, 2018): 969–76. http://dx.doi.org/10.1177/0022034518767120.
Full textAbstract:
Craniofacial bones, separate from the appendicular skeleton, bear a significant amount of strain and stress generated from mastication-related muscles. Current research on the regeneration of craniofacial bone focuses on the reestablishment of an elaborate vascular network. In this review, current challenges and efforts particularly in advances of scaffold properties and techniques for vascularization remodeling in craniofacial bone tissue engineering will be discussed. A microenvironment of ischemia and hypoxia in the biomaterial core drives propagation and reorganization of endothelial progenitor cells (EPCs) to assemble into a primitive microvascular framework. Co-culture strategies and delivery of vasculogenic molecules enhance EPCs’ differentiation and stimulate the host regenerative response to promote vessel sprouting and strength. To optimize structural and vascular integration, well-designed microstructures of scaffolds are biologically considered. Proper porous structures, matrix stiffness, and surface morphology of scaffolds have a profound influence on cell behaviors and thus affect revascularization. In addition, advanced techniques facilitating angiogenesis and vaculogenesis have also been discussed. Oxygen delivery biomaterials, scaffold-free cell sheet techniques, and arteriovenous loop-induced axial vascularization strategies bring us new understanding and powerful strategies to manage revascularization of large craniofacial bone defects. Although promising histological results have been achieved, the efficient perfusion and functionalization of newly formed vessels are still challenging.
29
Oliveira, Rui, Luís Freitas, Diogo Costa, José Vicente, Arminda Manuela Gonçalves, Teresa Malheiro, and José Machado. "A Systematic Analysis of Printed Circuit Boards Bending during In-Circuit Tests." Machines 10, no. 2 (February 13, 2022): 135. http://dx.doi.org/10.3390/machines10020135.
Full textAbstract:
When performing In-Circuit Tests (ICTs) of Printed Circuit Boards (PCBs), there are certain phenomena related with strain analysis that must be known in order to obtain stronger and more accurate testing results. During testing, PCBs are often subjected to mechanical bending efforts that induce excessive strain. This study focuses on the building of a Finite Elements Analysis (FEA) methodology that prevents excessive bending strain in critical points of a PCB during an ICT. To validate this methodology, a set of experimental tests, matched with a set of FEA, were carried out. Thus, companies, before the development of an ICT machine (fixture), will be able to use this FEA methodology to predict whether the maximum strain of a PCB under study, when subjected to its ICT, will damage it, thus reducing unnecessary production costs. A guideline was thus designed to enable the creation of the most representative Finite Elements Model (FEM) for any PCB, based on its amount and direction of copper traces.
30
Bačić, Mario, Lovorka Librić, Danijela Jurić Kaćunić, and Meho Saša Kovačević. "The Usefulness of Seismic Surveys for Geotechnical Engineering in Karst: Some Practical Examples." Geosciences 10, no. 10 (October 11, 2020): 406. http://dx.doi.org/10.3390/geosciences10100406.
Full textAbstract:
Having in mind uncertainties linked with the nature of rock masses, it is a challenge for geotechnical engineers to characterize them in a credible manner, especially if the rock mass in question is a notoriously complex karst with its distinctive features such as voids and discontinuities. A large range of geophysical methods are useful tools in the characterization efforts and their utilization in karst environments nowadays is a non-negotiable requirement, even though near-surface scattering significantly affects the acquired data. This paper demonstrates the versatile applications of seismic geophysical methods for geotechnical engineering in karst, from mapping of near-surface karstic features to the application of elastic wave velocities in determination of small to large strain stiffness of karst. The highlighted practical examples offer a step forward from the traditional interpretation of seismic surveys, making them a prosperous tool in geotechnical engineering investigation works, design and quality control campaign.
31
Garcia, Sergio, and Cong T. Trinh. "Comparison of Multi-Objective Evolutionary Algorithms to Solve the Modular Cell Design Problem for Novel Biocatalysis." Processes 7, no. 6 (June 11, 2019): 361. http://dx.doi.org/10.3390/pr7060361.
Full textAbstract:
A large space of chemicals with broad industrial and consumer applications could be synthesized by engineered microbial biocatalysts. However, the current strain optimization process is prohibitively laborious and costly to produce one target chemical and often requires new engineering efforts to produce new molecules. To tackle this challenge, modular cell design based on a chassis strain that can be combined with different product synthesis pathway modules has recently been proposed. This approach seeks to minimize unexpected failure and avoid task repetition, leading to a more robust and faster strain engineering process. In our previous study, we mathematically formulated the modular cell design problem based on the multi-objective optimization framework. In this study, we evaluated a library of state-of-the-art multi-objective evolutionary algorithms (MOEAs) to identify the most effective method to solve the modular cell design problem. Using the best MOEA, we found better solutions for modular cells compatible with many product synthesis modules. Furthermore, the best performing algorithm could provide better and more diverse design options that might help increase the likelihood of successful experimental implementation. We identified key parameter configurations to overcome the difficulty associated with multi-objective optimization problems with many competing design objectives. Interestingly, we found that MOEA performance with a real application problem, e.g., the modular strain design problem, does not always correlate with artificial benchmarks. Overall, MOEAs provide powerful tools to solve the modular cell design problem for novel biocatalysis.
32
Cao, Yujin, Rubing Zhang, Chao Sun, Tao Cheng, Yuhua Liu, and Mo Xian. "Fermentative Succinate Production: An Emerging Technology to Replace the Traditional Petrochemical Processes." BioMed Research International 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/723412.
Full textAbstract:
Succinate is a valuable platform chemical for multiple applications. Confronted with the exhaustion of fossil energy resources, fermentative succinate production from renewable biomass to replace the traditional petrochemical process is receiving an increasing amount of attention. During the past few years, the succinate-producing process using microbial fermentation has been made commercially available by the joint efforts of researchers in different fields. In this review, recent attempts and experiences devoted to reduce the production cost of biobased succinate are summarized, including strain improvement, fermentation engineering, and downstream processing. The key limitations and challenges faced in current microbial production systems are also proposed.
33
Kaljuzhnyj, V. L., and V. V. Pimanov. "Cold extrusion with differentiated counter-pressure of die cavities." Izvestiya MGTU MAMI 7, no. 2-2 (March 20, 2013): 32–37. http://dx.doi.org/10.17816/2074-0530-67982.
Full textAbstract:
The article describes the engineering method to obtain the correlation for the determination of stresses on the contact surfaces of the workpiece and the tool, the efforts of the extrusion of cavities by spherical die. It shows numerical simulations made on computer simulation by the finite element method on examples of extrusion by spherical die of billets made of R6M5 (Р6М5) steel under the action of counter-pressure on the free surface of the workpiece. The paper contains the definition of the maximum counter-pressure through simulation that provides extrusion without destruction and the efforts of the processes, the distribution of stresses in the deforming tool and the stress-strain state, the degree of resource use of metal plasticity, as well as the final product dimensions. The article contains a description of the experiment on the extrusion billets of steel R6M5 (Р6М5) spherical die.
34
Ren, Hongtao, and Gang Xiang. "Recent Progress in Research on Ferromagnetic Rhenium Disulfide." Nanomaterials 12, no. 19 (October 2, 2022): 3451. http://dx.doi.org/10.3390/nano12193451.
Full textAbstract:
Since long-range magnetic ordering was observed in pristine Cr2Ge2Te6 and monolayer CrCl3, two-dimensional (2D) magnetic materials have gradually become an emerging field of interest. However, it is challenging to induce and modulate magnetism in non-magnetic (NM) materials such as rhenium disulfide (ReS2). Theoretical research shows that defects, doping, strain, particular phase, and domain engineering may facilitate the creation of magnetic ordering in the ReS2 system. These predictions have, to a large extent, stimulated experimental efforts in the field. Herein, we summarize the recent progress on ferromagnetism (FM) in ReS2. We compare the proposed methods to introduce and modulate magnetism in ReS2, some of which have made great experimental breakthroughs. Experimentally, only a few ReS2 materials exhibit room-temperature long-range ferromagnetic order. In addition, the superexchange interaction may cause weak ferromagnetic coupling between neighboring trimers. We also present a few potential research directions for the future, and we finally conclude that a deep and thorough understanding of the origin of FM with and without strain is very important for the development of basic research and practical applications.
35
Li, Ming, and Daniel J. Lege. "Serrated Flow and Surface Markings in Aluminum Alloys." Journal of Engineering Materials and Technology 120, no. 1 (January 1, 1998): 48–56. http://dx.doi.org/10.1115/1.2806837.
Full textAbstract:
Serrated flow and associated progressive surface markings severely restrict the application of some aluminum sheet alloys for automotive body exteriors. This paper attempts to approach the phenomenon from the localization theory of continuum mechanics as well as from the classical atomistic and dislocation considerations. Plane strain tension tests were conducted for a commercial Al-Mg alloy (5182-O) at different strain rates and temperatures, and the local temperature changes were measured by an infrared thermal imaging system. Continuum mechanics analysis provided the insight into the myth that band surface markings never appear under biaxial tension strain states. In addition, continuum mechanics analysis shed light on the observation that PLC bands were not seen on the surface of plane strain tension specimens even though the stress-strain curves exhibited serrations. Finally, it is emphasized that only by combining the efforts of continuum mechanics at the macroscale and materials science at the microscale, can a complete understanding of the phenomenon be reached.
36
Bado, Mattia Francesco, and Joan R. Casas. "A Review of Recent Distributed Optical Fiber Sensors Applications for Civil Engineering Structural Health Monitoring." Sensors 21, no. 5 (March 5, 2021): 1818. http://dx.doi.org/10.3390/s21051818.
Full textAbstract:
The present work is a comprehensive collection of recently published research articles on Structural Health Monitoring (SHM) campaigns performed by means of Distributed Optical Fiber Sensors (DOFS). The latter are cutting-edge strain, temperature and vibration monitoring tools with a large potential pool, namely their minimal intrusiveness, accuracy, ease of deployment and more. Its most state-of-the-art feature, though, is the ability to perform measurements with very small spatial resolutions (as small as 0.63 mm). This review article intends to introduce, inform and advise the readers on various DOFS deployment methodologies for the assessment of the residual ability of a structure to continue serving its intended purpose. By collecting in a single place these recent efforts, advancements and findings, the authors intend to contribute to the goal of collective growth towards an efficient SHM. The current work is structured in a manner that allows for the single consultation of any specific DOFS application field, i.e., laboratory experimentation, the built environment (bridges, buildings, roads, etc.), geotechnical constructions, tunnels, pipelines and wind turbines. Beforehand, a brief section was constructed around the recent progress on the study of the strain transfer mechanisms occurring in the multi-layered sensing system inherent to any DOFS deployment (different kinds of fiber claddings, coatings and bonding adhesives). Finally, a section is also dedicated to ideas and concepts for those novel DOFS applications which may very well represent the future of SHM.
37
Shin, Hyun-Dong, Shara McClendon, Trinh Vo, and Rachel R. Chen. "Escherichia coli Binary Culture Engineered for Direct Fermentation of Hemicellulose to a Biofuel." Applied and Environmental Microbiology 76, no. 24 (October 8, 2010): 8150–59. http://dx.doi.org/10.1128/aem.00908-10.
Full textAbstract:
ABSTRACT Metabolic engineering has created several Escherichia coli biocatalysts for production of biofuels and other useful molecules. However, the inability of these biocatalysts to directly use polymeric substrates necessitates costly pretreatment and enzymatic hydrolysis prior to fermentation. Consolidated bioprocessing has the potential to simplify the process by combining enzyme production, hydrolysis, and fermentation into a single step but requires a fermenting organism to multitask by producing both necessary enzymes and target molecules. We demonstrate here a binary strategy for consolidated bioprocessing of xylan, a complex substrate requiring six hemicellulases for complete hydrolysis. An integrated modular approach was used to design the two strains to function cooperatively in the process of transforming xylan into ethanol. The first strain was engineered to coexpress two hemicellulases. Recombinant enzymes were secreted to the growth medium by a method of lpp deletion with over 90% efficiency. Secreted enzymes hydrolyzed xylan into xylooligosaccharides, which were taken in by the second strain, designed to use the xylooligosaccharides for ethanol production. Cocultivation of the two strains converted xylan hemicellulose to ethanol with a yield about 55% of the theoretical value. Inclusion of other three hemicellulases improved the ethanol yield to 70%. Analysis of the culture broth showed that xylooligosaccharides with four or more xylose units were not utilized, suggesting that improving the use of higher xyloogligomers should be the focus in future efforts. This is the first demonstration of an engineered binary culture for consolidated bioprocessing of xylan. The modular design should allow the strategy to be adopted for a broad range of biofuel and biorefinery products.
38
Xu, Hao, Qi Zhou, Lei Yang, Minjing Liu, Dongyue Gao, Zhanjun Wu, and Maosen Cao. "Reconstruction of full-field complex deformed shapes of thin-walled special-section beam structures based on in situ strain measurement." Advances in Structural Engineering 23, no. 15 (July 4, 2020): 3335–50. http://dx.doi.org/10.1177/1369433220937156.
Full textAbstract:
This study proposed a method capable of reconstructing complex deformations of thin-walled special-section beam structures subjected to highly coupled loading cases, in terms of the combination of tension/compression, biaxial bending, and warping torsion. The complex beam deformation was decoupled, depending on axial strain measurement strategy on beam surface, and leads to reconstructed full-field displacements (deformed shapes) as the linear superposition of deformations subject to individual loading types. Full-filed strain/stress distributions can then be derived based on the reconstructed displacements. Particular efforts were focused on reconstructing beam deformation subject to warping torsion, where both rotations angles and warping displacements across the beam cross-section and along the beam length were identified precisely. As a proof-of-concept validation, the effectiveness of the method was examined using finite element analysis, where the deformed shape of a thin-walled hat-section beam under the coupling between uniaxial bending and warping torsion was reconstructed., Experiments were conducted subsequently to reconstruct deformation of an aluminum hat-section beam using distributed optical fiber sensors for the measurement of axial strains on the beam surface. The reconstructed full-field deformed shapes of the beam were compared with the three-dimensional displacement signals captured using a non-contact digital image correlation system. The effectiveness of the proposed methodology for complex deformation reconstruction is possible to be extended to a variety of thin-walled beam-type structures which are typical in civil and aerospace engineering, showing potential contributions in fields such as on-line structural health monitoring and active structural control.
39
Sibal, Prateek, G. Dinesh Babu, and M. Nageswara Rao. "Use of Strain Energy Density W and Qo as Quality Indices for Rating the Quality of Cast Aluminium Alloy354 as a Function of Processing Parameters." Advanced Materials Research 704 (June 2013): 189–94. http://dx.doi.org/10.4028/www.scientific.net/amr.704.189.
Full textAbstract:
Cast aluminium alloy 354 has found widespread application in the automotive industry for its excellent mechanical properties and good castability. The stringent emission norms and demands for improved fuel economy have pushed automobile technology to new frontiers. This has led to efforts to reduce weight while maintaining higher vehicle performance. Cast aluminium alloy 354 is a material that performs with reasonable effectiveness in the high stress automobile environment. The present study looks at the use of strain energy density W and the quality index Qo to determine the effect of process parameters like aging temperature and modification on the quality of the alloy 354 and also to monitor the effect of interrupted heat treatments T6I4 and T6I6 on the quality of the material. The strain energy density W calculated for the interrupted heat treatments on alloy 354 show a broad inverse relation with yield strength Rp. An improvement in the yield strength and the strain energy density of the alloy is observed when the alloy is subjected to modification. At artificial aging temperatures lower than the artificial aging temperature adopted in standard aging treatment an improvement in the Qo and W quality of the alloy 354 have been observed.
40
Knysh, Oleh, Ivan Reheі, Nazar Kandiak, Serhij Ternytskyi, and Bohdan Ivaskiv. "Experimental Evaluation of Eccentric Mechanism Power Loading of Movable Pressure Plate in Die-Cutting Press." Acta Mechanica et Automatica 16, no. 3 (September 1, 2022): 266–73. http://dx.doi.org/10.2478/ama-2022-0032.
Full textAbstract:
Abstract The paper reports experimental research on torques during cardboard cutting in the die-cutting press with eccentrics in the drive of the movable pressure plate. To conduct the research, an experimental bench with eccentrics in the drive of the die-cutting press is designed and manufactured. The manufactured experimental device for the research on cardboard blanks provides the possibility of getting dependencies of loadings at different parameters of the die-cutting process. The experimental approach envisages the use of the strain gauge measurement method and the wireless module for data collecting, as well as the software for its processing, for getting trustworthy results with minimum faults. The method gives an opportunity to study the torque values during the cardboard-cutting efforts on the drive shaft. The paper shows changes in the torque value on the drive shaft during the kinematic cycle with and without the use of cardboard blank. The angle of the drive shaft rotation during the cutting process was evaluated at selected values of the cardboard thickness. The relationship between the linear cutting efforts and the cardboard thickness, its fibre direction, cutting rule type and rotational speed of the drive shaft is elaborated. This kind of data is approximated by a logarithmic function (logarithmic curve), at R 2 from 0.90 to 0.98. The thickness of the cardboard significantly influences the value of the linear cutting effort at all the studied parameters.
41
Han, Fei, Min Li, Huaiyu Ye, and Guoqi Zhang. "Materials, Electrical Performance, Mechanisms, Applications, and Manufacturing Approaches for Flexible Strain Sensors." Nanomaterials 11, no. 5 (May 5, 2021): 1220. http://dx.doi.org/10.3390/nano11051220.
Full textAbstract:
With the recent great progress made in flexible and wearable electronic materials, the upcoming next generation of skin-mountable and implantable smart devices holds extensive potential applications for the lifestyle modifying, including personalized health monitoring, human-machine interfaces, soft robots, and implantable biomedical devices. As a core member within the wearable electronics family, flexible strain sensors play an essential role in the structure design and functional optimization. To further enhance the stretchability, flexibility, sensitivity, and electricity performances of the flexible strain sensors, enormous efforts have been done covering the materials design, manufacturing approaches and various applications. Thus, this review summarizes the latest advances in flexible strain sensors over recent years from the material, application, and manufacturing strategies. Firstly, the critical parameters measuring the performances of flexible strain sensors and materials development contains different flexible substrates, new nano- and hybrid- materials are introduced. Then, the developed working mechanisms, theoretical analysis, and computational simulation are presented. Next, based on different material design, diverse applications including human motion detection and health monitoring, soft robotics and human-machine interface, implantable devices, and biomedical applications are highlighted. Finally, synthesis consideration of the massive production industry of flexible strain sensors in the future; different fabrication approaches that are fully expected are classified and discussed.
42
Ko, Yelin, Ji-seon Kim, Chi Cuong Vu, and Jooyong Kim. "Ultrasensitive Strain Sensor Based on Pre-Generated Crack Networks Using Ag Nanoparticles/Single-Walled Carbon Nanotube (SWCNT) Hybrid Fillers and a Polyester Woven Elastic Band." Sensors 21, no. 7 (April 4, 2021): 2531. http://dx.doi.org/10.3390/s21072531.
Full textAbstract:
Flexible strain sensors are receiving a great deal of interest owing to their prospective applications in monitoring various human activities. Among various efforts to enhance the sensitivity of strain sensors, pre-crack generation has been well explored for elastic polymers but rarely on textile substrates. Herein, a highly sensitive textile-based strain sensor was fabricated via a dip-coat-stretch approach: a polyester woven elastic band was dipped into ink containing single-walled carbon nanotubes coated with silver paste and pre-stretched to generate prebuilt cracks on the surface. Our sensor demonstrated outstanding sensitivity (a gauge factor of up to 3550 within a strain range of 1.5–5%), high stability and durability, and low hysteresis. The high performance of this sensor is attributable to the excellent elasticity and woven structure of the fabric substrate, effectively generating and propagating the prebuilt cracks. The strain sensor integrated into firefighting gloves detected detailed finger angles and cyclic finger motions, demonstrating its capability for subtle human motion monitoring. It is also noteworthy that this novel strategy is a very quick, straightforward, and scalable method of fabricating strain sensors, which is extremely beneficial for practical applications.
43
Mostert, Dylan, Bart Groenen, Leda Klouda, Robert Passier, Marie-Jose Goumans, Nicholas A. Kurniawan, and Carlijn V. C. Bouten. "Human pluripotent stem cell-derived cardiomyocytes align under cyclic strain when guided by cardiac fibroblasts." APL Bioengineering 6, no. 4 (December 1, 2022): 046108. http://dx.doi.org/10.1063/5.0108914.
Full textAbstract:
The myocardium is a mechanically active tissue typified by anisotropy of the resident cells [cardiomyocytes (CMs) and cardiac fibroblasts (cFBs)] and the extracellular matrix (ECM). Upon ischemic injury, the anisotropic tissue is replaced by disorganized scar tissue, resulting in loss of coordinated contraction. Efforts to re-establish tissue anisotropy in the injured myocardium are hampered by a lack of understanding of how CM and/or cFB structural organization is affected by the two major physical cues inherent in the myocardium: ECM organization and cyclic mechanical strain. Herein, we investigate the singular and combined effect of ECM (dis)organization and cyclic strain in a two-dimensional human in vitro co-culture model of the myocardial microenvironment. We show that (an)isotropic ECM protein patterning can guide the orientation of CMs and cFBs, both in mono- and co-culture. Subsequent application of uniaxial cyclic strain—mimicking the local anisotropic deformation of beating myocardium—causes no effect when applied parallel to the anisotropic ECM. However, when cultured on isotropic substrates, cFBs, but not CMs, orient away from the direction of cyclic uniaxial strain (strain avoidance). In contrast, CMs show strain avoidance via active remodeling of their sarcomeres only when co-cultured with at least 30% cFBs. Paracrine signaling or N-cadherin-mediated communication between CMs and cFBs was no contributing factor. Our findings suggest that the mechanoresponsive cFBs provide structural guidance for CM orientation and elongation. Our study, therefore, highlights a synergistic mechanobiological interplay between CMs and cFBs in shaping tissue organization, which is of relevance for regenerating functionally organized myocardium.
44
Sengupta, Sudeshna, Sudhakar Jonnalagadda, Lakshani Goonewardena, and Veeresh Juturu. "Metabolic Engineering of a Novel Muconic Acid Biosynthesis Pathway via 4-Hydroxybenzoic Acid in Escherichia coli." Applied and Environmental Microbiology 81, no. 23 (September 11, 2015): 8037–43. http://dx.doi.org/10.1128/aem.01386-15.
Full textAbstract:
ABSTRACTcis,cis-Muconic acid (MA) is a commercially important raw material used in pharmaceuticals, functional resins, and agrochemicals. MA is also a potential platform chemical for the production of adipic acid (AA), terephthalic acid, caprolactam, and 1,6-hexanediol. A strain ofEscherichia coliK-12, BW25113, was genetically modified, and a novel nonnative metabolic pathway was introduced for the synthesis of MA from glucose. The proposed pathway converted chorismate from the aromatic amino acid pathway to MA via 4-hydroxybenzoic acid (PHB). Three nonnative genes,pobA,aroY, andcatA, coding for 4-hydroxybenzoate hydrolyase, protocatechuate decarboxylase, and catechol 1,2-dioxygenase, respectively, were functionally expressed inE. colito establish the MA biosynthetic pathway.E. colinative genesubiC,aroFFBR,aroE, andaroLwere overexpressed and the genesptsH,ptsI,crr, andpykFwere deleted from theE. coligenome in order to increase the precursors of the proposed MA pathway. The final engineeredE. colistrain produced nearly 170 mg/liter of MA from simple carbon sources in shake flask experiments. The proposed pathway was proved to be functionally active, and the strategy can be used for future metabolic engineering efforts for production of MA from renewable sugars.
45
Hook, Christine, Natalya Eremina, Petr Zaytsev, Daria Varlamova, and Nataliya Stoynova. "The Escherichia coli Amino Acid Uptake Protein CycA: Regulation of Its Synthesis and Practical Application in l-Isoleucine Production." Microorganisms 10, no. 3 (March 17, 2022): 647. http://dx.doi.org/10.3390/microorganisms10030647.
Full textAbstract:
Amino acid transport systems perform important physiological functions; their role should certainly be considered in microbial production of amino acids. Typically, in the context of metabolic engineering, efforts are focused on the search for and application of specific amino acid efflux pumps. However, in addition, importers can also be used to improve the industrial process as a whole. In this study, the protein CycA, which is known for uptake of nonpolar amino acids, was characterized from the viewpoint of regulating its expression and range of substrates. We prepared a cycA-overexpressing strain and found that it exhibited high sensitivity to branched-chain amino acids and their structural analogues, with relatively increased consumption of these amino acids, suggesting that they are imported by CycA. The expression of cycA was found to be dependent on the extracellular concentrations of substrate amino acids. The role of some transcription factors in cycA expression, including of Lrp and Crp, was studied using a reporter gene construct. Evidence for the direct binding of Crp to the cycA regulatory region was obtained using a gel-retardation assay. The enhanced import of named amino acids due to cycA overexpression in the l-isoleucine-producing strain resulted in a significant reduction in the generation of undesirable impurities. This work demonstrates the importance of uptake systems with respect to their application in metabolic engineering.
46
Javidpour, Pouya, Jose H. Pereira, Ee-Been Goh, Ryan P. McAndrew, Suzanne M. Ma, Gregory D. Friedland, Jay D. Keasling, Swapnil R. Chhabra, Paul D. Adams, and Harry R. Beller. "Biochemical and Structural Studies of NADH-Dependent FabG Used To Increase the Bacterial Production of Fatty Acids under Anaerobic Conditions." Applied and Environmental Microbiology 80, no. 2 (November 8, 2013): 497–505. http://dx.doi.org/10.1128/aem.03194-13.
Full textAbstract:
ABSTRACTMajor efforts in bioenergy research have focused on producing fuels that can directly replace petroleum-derived gasoline and diesel fuel through metabolic engineering of microbial fatty acid biosynthetic pathways. Typically, growth and pathway induction are conducted under aerobic conditions, but for operational efficiency in an industrial context, anaerobic culture conditions would be preferred to obviate the need to maintain specific dissolved oxygen concentrations and to maximize the proportion of reducing equivalents directed to biofuel biosynthesis rather than ATP production. A major concern with fermentative growth conditions is elevated NADH levels, which can adversely affect cell physiology. The purpose of this study was to identify homologs ofEscherichia coliFabG, an essential reductase involved in fatty acid biosynthesis, that display a higher preference for NADH than for NADPH as a cofactor. Four potential NADH-dependent FabG variants were identified through bioinformatic analyses supported by crystallographic structure determination (1.3- to 2.0-Å resolution).In vitroassays of cofactor (NADH/NADPH) preference in the four variants showed up to ∼35-fold preference for NADH, which was observed with theCupriavidus taiwanensisFabG variant. In addition, FabG homologs were overexpressed in fatty acid- and methyl ketone-overproducingE. colihost strains under anaerobic conditions, and theC. taiwanensisvariant led to a 60% higher free fatty acid titer and 75% higher methyl ketone titer relative to the titers of the control strains. With further engineering, this work could serve as a starting point for establishing a microbial host strain for production of fatty acid-derived biofuels (e.g., methyl ketones) under anaerobic conditions.
47
Rey-De-Pedraza, V., D. A. Cendón, V. Sánchez-Gálvez, and F. Gálvez. "Measurement of fracture properties of concrete at high strain rates." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2085 (January 28, 2017): 20160174. http://dx.doi.org/10.1098/rsta.2016.0174.
Full textAbstract:
An analysis of the spalling technique of concrete bars using the modified Hopkinson bar was carried out. A new experimental configuration is proposed adding some variations to previous works. An increased length for concrete specimens was chosen and finite-element analysis was used for designing a conic projectile to obtain a suitable triangular impulse wave. The aim of this initial work is to establish an experimental framework which allows a simple and direct analysis of concrete subjected to high strain rates. The efforts and configuration of these primary tests, as well as the selected geometry and dimensions for the different elements, have been focused to achieve a simple way of identifying the fracture position and so the tensile strength of tested specimens. This dynamic tensile strength can be easily compared with previous values published in literature giving an idea of the accuracy of the method and technique proposed and the possibility to extend it in a near future to obtain other mechanical properties such as the fracture energy. The tests were instrumented with strain gauges, accelerometers and high-speed camera in order to validate the results by different ways. Results of the dynamic tensile strength of the tested concrete are presented. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.
48
Wood, Clinton M., and Brady R. Cox. "Experimental Data Set of Mining-Induced Seismicity for Studies of Full-Scale Topographic Effects." Earthquake Spectra 31, no. 1 (February 2015): 541–64. http://dx.doi.org/10.1193/020314eqs026.
Full textAbstract:
This paper describes two large, high-quality experimental data sets of ground motions collected with locally dense arrays of seismometers deployed on steep mountainous terrain with varying slope angles and topographic features. These data sets were collected in an area of central-eastern Utah that experiences frequent and predictable mining-induced seismicity as a means to study the effects of topography on small-strain seismic ground motions. The data sets are freely available through the George E. Brown, Jr. Network for Earthquake Engineering Simulation data repository ( NEEShub.org ) under the DOI numbers 10.4231/D34M9199S and 10.4231/D3Z31NN4J. This paper documents the data collection efforts and metadata necessary for utilizing the data sets, as well as the availability of supporting data (e.g., high-resolution digital elevation models). The paper offers a brief summary of analyses conducted on the data sets thus far, in addition to ideas about how these data sets may be used in future studies related to topographic effects and mining seismicity.
49
Halford, G. R., T. G. Meyer, R. S. Nelson, D. M. Nissley, and G. A. Swanson. "Fatigue Life Prediction Modeling for Turbine Hot Section Materials." Journal of Engineering for Gas Turbines and Power 111, no. 2 (April 1, 1989): 279–85. http://dx.doi.org/10.1115/1.3240249.
Full textAbstract:
This paper presents a summary of the life prediction methods developed under the NASA Lewis Research Center’s Hot Section Technology (HOST) program. A major objective of the fatigue and fracture efforts under the HOST program was to significantly improve the analytic life prediction tools used by the aeronautical gas turbine engine industry. This has been achieved in the areas of high-temperature thermal and mechanical fatigue of bare and coated high-temperature superalloys. Such technical improvements will eventually reduce life cycle costs. The cyclic crack initiation and propagation resistance of nominally isotropic polycrystalline alloys and highly anisotropic single crystal alloys have been addressed. A sizeable data base has been generated for three alloys [cast PWA 1455 (B–1900 + Hf), wrought Inconel 718, and cast single-crystal PWA 1480] in bare and coated conditions. Two coating systems, diffusion aluminide (PWA 273) and plasma-sprayed MCrAlY overlay (PWA 286), were employed. Life prediction modeling efforts were devoted to creep-fatigue interaction, oxidation, coatings interactions, multiaxially of stress-strain states, mean stress effects, cumulative damage, and thermomechanical fatigue. The fatigue crack initiation life models developed to date include the Cyclic Damage Accumulation (CDA) Model of Pratt & Whitney and the Total Strain Version of Strainrange Partitioning (TS-SRP) of NASA Lewis for nominally isotropic materials, and the Tensile Hysteretic Energy Model of Pratt & Whitney for anisotropic superalloys. The fatigue model being developed by the General Electric Company is based upon the concepts of Path-Independent Integrals (PII) for describing cyclic crack growth under complex non-linear response at the crack tip due to thermomechanical loading conditions. A micromechanistic oxidation crack extension model has been derived by researchers at Syracuse University. The models are described and discussed in the paper. Only limited verification has been achieved to date as several of the technical programs are still in progress and the verification tasks are scheduled, quite naturally, near the conclusion of the program. To date, efforts have concentrated on developement of independent models for cyclic constitutive behavior, cyclic crack initiation, and cyclic crack propagation. The transition between crack initiation and crack propagation has not been thoroughly researched as yet, and the integration of these models into a unified life prediction method has not been addressed.
50
Metelkin, Sergey, and Vladimir Paramonov. "Frost Heave and Its Influence on Spacer System of Enclosing Constructions of Deep Ditches." Proceedings of Petersburg Transport University 19, no. 1 (March 24, 2022): 133–42. http://dx.doi.org/10.20295/1815-588x-2022-19-1-133-142.
Full textAbstract:
Purpose: Research of interaction between ditch fencing constructions and ground massive in negative temperature period. Methods: Pursuing nature measurements on active construction site and numerical modeling. Data on stress-strain state of “ditch fencing -ground massive” system were obtained; the comparison of experimental data with calculation results were made; the proposal on accounting for additional efforts against frost heave in the system “ditch fencing -ground massive” was formulated. Results: It was established that magnitude of forces of frost heave can be significant that says on the necessity to consider them while engineering of unfastened ditch fencings. It follows according to obtained calculation estimation of frost heave forces effecting fencings that it’s necessary not just to take into account a ground freezing depth but also negative temperature values which at, efforts in ditch fencing constructions can reach the maximum. Practical importance: At comparison of experimental data with retaining wall calculation results, the factors are determined which out of, the loss of bearing capability of spacer system particular elements is possible. There’re also obtained the detailed data on joint work of fencing and ground massive at active construction site in geotechnical conditions of Saint-Petersburg.