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Sample records for mechanical activation technique

  1. Activated mechanisms in proteins: a multiple-temperature activation-relaxation technique study

    Science.gov (United States)

    Malek, Rachid; Mousseau, Normand; Derreumaux, Philippe

    2001-03-01

    The low-temperature dynamics of proteins is controlled by a complex activated dynamics taking place over long time-scales compared with the period of thermal oscillations. In view of the range of relevant time scales, the numerical study of these processes remains a challenge and numerous methods have been introduced to address this problem. We introduce here a mixture of two algorithms, the activation-relaxation technique (ART)^1,2 coupled with the parallel tempering method, and use it to study the structure of the energy landscape around the native state of a 38-residue polypeptide. While ART samples rapidly the local energy landscape, the parallel tempering, which sets up exchanges of configuration between simultaneous runs at multiple temperatures, generates a very efficient sampling of energy basins separated by high barriers^(3). Results show the nature of the barriers and local minima surrounding the native state of this 38-residue peptide, modeled with off-lattice OPEP-like interactions^4. (1) G.T. Barkema and N. Mousseau, PRL 77, 4358 (1996) (2) N. Mousseau and G.T. Barkema, PRE 57, 2419 (1998) (3) E. Marinari and G. Parisi, Europhys. Lett., 19 (6), 451 (1992) (4) Ph. Derreumaux, J. Chem. Phys. 111, 2301 (1999); PRB 85, 206 (2000)

  2. Exploring the assembly mechanism of tetrapeptide oligomers using the Activation-Relaxation Technique

    Science.gov (United States)

    Wei, Guanghong; Mousseau, Normand; Derreumaux, Philippe

    2004-03-01

    Alzheimer's disease and Parkinson's disease are associated with formation of amyloid fibrils. All amyloid fibrils seem to share a common cross β-sheet structure. Experimental studies have shown that peptides as short as 4 amino acids can form amyloid fibrils. It has also been shown that the oligomers that form early in the aggregation process of even non-disease-related proteins may be cytotoxic. We report a detailed study of the assembly mechanisms of the tetrapeptides into different size oligomers: trimers, hexamers and more. The assembly of the oligomers, in which the peptides form β-sheets through interpeptide interactions, are studied using the activation-relaxation technique (ART) in combination with a reduced off-lattice energy model (OPEP). We also describe the multiple pathways of oligomerization as well as categorize the various oligomeric intermediates, providing information of the early events of β-sheet formation.

  3. Graphite-to-304SS Braze Joining by Active Metal-Brazing Technique: Improvement of Mechanical Properties

    Science.gov (United States)

    Ray, Ajoy K.; Kar, Abhijit; Kori, S. A.; Pathak, L. C.; Sonnad, A. N.

    2013-01-01

    In the present investigation, an attempt has been made to improve the mechanical strength of graphite-stainless steel-brazed joint. Due to high capillary action, the liquid filler alloy usually tends to percolate into the pores of graphite causing severe stress in the graphite near the joint interface resulting in poor joint strength of 10-15 MPa. In the present investigation, a thin coating of SiC was applied on graphite before the joining process to avoid the penetration of liquid filler alloy into the pores of the graphite. Active filler alloy Ag-Cu-Ti was used to braze the substrates. The brazing was carried out at 850, 900, 950, and 1000 °C. The characterization of the interfaces of the brazed joints was carried out using scanning electron microscopy attached with energy dispersive spectroscopy and x-ray diffraction analysis. From the correlation between the microstructural and mechanical properties, shear strength of approximately 35 MPa for graphite-304SS-brazed joint produced at 900 °C was demonstrated. After the shear tests, the fracture surfaces were analyzed by SEM-EDS.

  4. Biological activity and mechanical stability of sol-gel-based biofilters using the freeze-gelation technique for immobilization of Rhodococcus ruber.

    Science.gov (United States)

    Pannier, Angela; Mkandawire, Martin; Soltmann, Ulrich; Pompe, Wolfgang; Böttcher, Horst

    2012-02-01

    Biofilters with long lifetime and high storage stability are very important for bioremediation processes to ensure the readiness at the occurrence of sudden contaminations. By using the freeze-gelation technique, living cells can be immobilized within a mechanically and chemically stable ceramic-like matrix. Due to a freeze-drying step, the embedded microorganisms are converted into a preserved form. In that way, they can be stored under dry conditions, which comply better with storage, transport, and handling requirements. Thus, in contrast to other immobilization techniques, there is no need for storage in liquid or under humid atmosphere. The biological activity, mechanical strength, and the structure of the biologically active ceramic-like composites (biocers) produced by freeze gelation have been investigated by using the phenol-degrading bacteria Rhodococcus ruber as model organism. Samples of freeze-gelation biocers have been investigated after defined storage periods, demonstrating nearly unchanged mechanical strength of the immobilization matrix as well as good storage stability of the activity of the immobilized cells over several months of storage at 4 °C. Repeated-batch tests demonstrated further that the freeze-gelation biocers can be repeatedly used over a period of more than 12 months without losing its bioactivity. Thus, these results show that freeze-gelation biocers have high potential of being scaled up from laboratory test systems to applications in real environment because of their long bioactivity as well as mechanical stability.

  5. Techniques for active passivation

    Energy Technology Data Exchange (ETDEWEB)

    Roscioli, Joseph R.; Herndon, Scott C.; Nelson, Jr., David D.

    2016-12-20

    In one embodiment, active (continuous or intermittent) passivation may be employed to prevent interaction of sticky molecules with interfaces inside of an instrument (e.g., an infrared absorption spectrometer) and thereby improve response time. A passivation species may be continuously or intermittently applied to an inlet of the instrument while a sample gas stream is being applied. The passivation species may have a highly polar functional group that strongly binds to either water or polar groups of the interfaces, and once bound presents a non-polar group to the gas phase in order to prevent further binding of polar molecules. The instrument may be actively used to detect the sticky molecules while the passivation species is being applied.

  6. Techniques for active passivation

    Science.gov (United States)

    Roscioli, Joseph R.; Herndon, Scott C.; Nelson, Jr., David D.

    2016-12-20

    In one embodiment, active (continuous or intermittent) passivation may be employed to prevent interaction of sticky molecules with interfaces inside of an instrument (e.g., an infrared absorption spectrometer) and thereby improve response time. A passivation species may be continuously or intermittently applied to an inlet of the instrument while a sample gas stream is being applied. The passivation species may have a highly polar functional group that strongly binds to either water or polar groups of the interfaces, and once bound presents a non-polar group to the gas phase in order to prevent further binding of polar molecules. The instrument may be actively used to detect the sticky molecules while the passivation species is being applied.

  7. Mechanism of mechanical activation for sulfide ores

    Institute of Scientific and Technical Information of China (English)

    HU Hui-ping; CHEN Qi-yuan; YIN Zhou-lan; HE Yue-hui; HUANG Bai-yun

    2007-01-01

    Structural changes for mechanically activated pyrite, sphalerite, galena and molybdenite with or without the exposure to ambient air, were systematically investigated using X-ray diffraction analysis(XRD), particle size analysis, gravimetrical method, X-ray photo-electron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers, several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained. For brittle sulfide ores with thermal instability, and incomplete cleavage plane or extremely incomplete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with thermal instability, and complete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed, and lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with excellent thermal stability, and complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For sulfide ores with high toughness, good thermal stability and very excellent complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation, but the lattice deformation ratio is very small. The effects of mechanical activation are worst.

  8. Fish Spoilage Mechanisms and Preservation Techniques: Review

    Directory of Open Access Journals (Sweden)

    Abdel E. Ghaly

    2010-01-01

    Full Text Available Problem statement: Spoilage of food products is due to chemical, enzymatic or microbial activities One-fourth of the worlds food supply and 30% of landed fish are lost through microbial activity alone. With the ever growing world population and the need to store and transport the food from one place to another where it is needed, food preservation becomes necessary in order to increase its shelf life and maintain its nutritional value, texture and flavor. The freshness and quality of fish have always gained the attention by Food Regulatory Agencies and Food Processing Industry. Proper handling, pretreatment and preservation techniques can improve the quality fish and fish products and increase their shelf life. Methodology: Historically salting, drying, smoking, fermentation and canning were the methods to prevent fish spoilage and extend its shelf life. In response to consumer demand for texture, appearance and taste, new methods were developed including: Cooling, freezing and chemical preservation. A comprehensive review of the literature on the subject of fish spoilage and modern preservation techniques was carried out. Conclusion: Fish spoilage results from three basic mechanisms: Enzymatic autolysis, oxidation, microbial growth. Low temperature storage and chemical techniques for controlling water activity, enzymatic, oxidative and microbial spoilage are the most common in the industry today. A process involving the addition of an EDTA (1 mM-TBHQ (0.02% combination and ascorbic acid and storage at refrigerated temperatures (5°C in darkness can be the most positive for controlling the spoilage of fish and fish product. The suggested process would address antimicrobial activity as well as destructive oxidation of the desired lipids and fats. However, more efforts are required to understand the role of proximate composition of fish, post harvest history, environmental conditions, initial microbial load, type and nature of bacteria and their

  9. Aerobic rice mechanization: techniques for crop establishment

    Science.gov (United States)

    Khusairy, K. M.; Ayob, H.; Chan, C. S.; Fauzi, M. I. Mohamed; Mohamad Fakhrul, Z. O.; Shahril Shah, G. S. M.; Azlan, O.; Rasad, M. A.; Hashim, A. M.; Arshad, Z.; E, E. Ibrahim; Saifulizan, M. N.

    2015-12-01

    Rice being the staple food crops, hundreds of land races in it makes the diversity of rice crops. Aerobic rice production was introduced which requires much less water input to safeguard and sustain the rice production and conserve water due to decreasing water resources, climatic changes and competition from urban and industrial users. Mechanization system plays an important role for the success of aerobic rice cultivation. All farming activities for aerobic rice production are run on aerobic soil conditions. Row seeder mechanization system is developed to replace conventional seeding technique on the aerobic rice field. It is targeted for small and the large scale aerobic rice farmers. The aero - seeder machine is used for the small scale aerobic rice field, while the accord - seeder is used for the large scale aerobic rice field. The use of this mechanization machine can eliminate the tedious and inaccurate seeding operations reduce labour costs and increases work rate. The machine is easy to operate and it can increase crop establishment rate. It reduce missing hill, increasing planting and crop with high yield can be produce. This machine is designed for low costs maintenance and it is easy to dismantle and assemble during maintenance and it is safe to be used.

  10. Mechanism of charity activity

    Directory of Open Access Journals (Sweden)

    Roman B. Golovkin

    2015-12-01

    Full Text Available Objective to establish the essential properties of the mechanism of charitable activities and to formulate the concept of quotmechanism of charitable activityquot. Methods the objective of the study is achieved using the complex of methods which are based on the interaction of dialectical and metaphysical analysis the epistemological properties of which allowed to reveal various aspects of the charitable activities mechanism functioning taking into account the principles of comprehensiveness complexity specificity and objectivity of the research. Results the rules are stated of using the term quotmechanismquot to characterize actions of state and law the essence of the charity mechanism is defined the definition of quotthe mechanism of charitable activity quot is formulated. Scientific novelty for the first time at theoretical level in legal science the definition of quotthe mechanism of charitable activityquot is formulated and its essential properties are set. Practical significance the research will contribute to improving the legal regulation in the field of philanthropy as well as to improving the efficiency and quality of charitable activity in the Russian Federation. nbsp

  11. [Inflammasome: activation mechanisms].

    Science.gov (United States)

    Suárez, Raibel; Buelvas, Neudo

    2015-03-01

    Inflammation is a rapid biologic response of the immune system in vascular tissues, directed to eliminate stimuli capable of causing damage and begin the process of repair. The macromolecular complexes known as "inflammasomes" are formed by a receptor, either NOD (NLR) or ALR, the receptor absent in melanoma 2 (AIM2). In addition, the inflammasome is formed by the speck-like protein associated to apoptosis (ASC) and procaspase-1, that may be activated by variations in the ionic and intracellular and extracellular ATP concentrations; and the loss of stabilization of the fagolisosomme by internalization of insoluble crystals and redox mechanisms. As a result, there is activation of the molecular platform and the processing of inflammatory prointerleukins to their active forms. There are two modalities of activation of the inflammasome: canonical and non-canonical, both capable of generating effector responses. Recent data associate NLRP 3, IL-1β and IL-18 in the pathogenesis of a variety of diseases, including atherosclerosis, type II diabetes, hyperhomocysteinemia, gout, malaria and hypertension. The inflammasome cascade is emerging as a new chemotherapeutic target in these diseases. In this review we shall discuss the mechanisms of activation and regulation of the inflammasome that stimulate, modulate and resolve inflammation.

  12. Generalized Borel transform technique in quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Marucho, M

    2003-03-13

    We present the Generalized Borel Transform (GBT). This new approach allows one to obtain approximate solutions of Laplace/Mellin transform valid in both, perturbative and non-perturbative regimes. We compare the results provided by the GBT for a solvable model of quantum mechanics with those provided by standard techniques, as the conventional Borel sum, or its modified versions. We found that our approach is very efficient for obtaining both the low and the high energy behavior of the model.

  13. Mechanism for the activation of glutamate receptors

    Science.gov (United States)

    Scientists at the NIH have used a technique called cryo-electron microscopy to determine a molecular mechanism for the activation and desensitization of ionotropic glutamate receptors, a prominent class of neurotransmitter receptors in the brain and spina

  14. Ineffective cough and mechanical mucociliary clearance techniques.

    Science.gov (United States)

    Fernández-Carmona, A; Olivencia-Peña, L; Yuste-Ossorio, M E; Peñas-Maldonado, L

    2017-06-12

    Cough is a fundamental defense mechanism for keeping the airway free of foreign elements. Life-threatening situations may arise when cough proves ineffective as a result of muscle weakness or altered mucociliary function. When a patient is unable to cough effectively, techniques are required to either reinforce or replace cough capacity. The use of mechanical systems that facilitate or substitute cough function is increasingly common in Intensive Care Units, where it is relatively frequent to find situations of ineffective cough due to different clinical causes. This review examines the current clinical practice recommendations referred to the indication and use of mechanical cough assist and intrapulmonary percussive ventilation systems. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  15. An analysis in vivo of intracanal bacterial load before and after chemo-mechanical preparation: A comparative analysis of two irrigants and two activation techniques

    Science.gov (United States)

    Rico-Romano, Cristina; Zubizarreta-Macho, Álvaro; Baquero-Artigao, María-Rosario

    2016-01-01

    Background The goals of this randomized double-blind trial were to assess the antimicrobial activity in vivo of Sodium hypochlorite (NaOCl) vs. chlorhexidine gluconate (CHX) used in combination either with EndoActivator® or IRRI S® files in patients with apical periodontitis. Material and Methods A total of 120 patients with apical periodontitis (in single or multiple root canals) were randomly assigned to the four irrigation protocols outlined below: Group A: 5.25% sodium hypochlorite (NaOCl) + EndoActivator®; Group B: 5.25% NaOCl + IRRI S® files; Group C: 2% chlorhexidine gluconate (CHX) + EndoActivator®; Group D: 2% CHX + IRRI S® files. Paper points were used to collect microbiological samples before (1A samples) and after (1B samples) irrigation. Viable colony-forming units (CFU) were quantified twice: (1) without speciation, and (2) only for Enterococcus Faecalis(EF). Statistical analysis was performed using SPSS 22.0 for Windows. Results No significant differences were observed between NaOCl and CHX in the reduction of CFU; in fact, reduction was irrigants. Conversely, statistically significant differences were found between the two activation techniques (sonic and ultrasonic) in the reduction of Enterococcus Faecalis(EF). Thus, the effectiveness of ultrasonic activation was significantly higher (irrigants with the two activation techniques (groups A, B, C and D), significant differences were observed between group A and B (p=0.025) in the reduction of EF populations, reaching up to 94%. Conclusions NaClO and CHX are effective in reducing intracanal bacterial load. Ultrasonic activation is the most effective activation technique in reducing EF populations. Key words:Chlorhexidine gluconate, sodium hypochlorite, ultrasonic irrigation, sonic irrigation, apical periodontitis, Enterococcus faecalis. PMID:26855714

  16. Sputtering. [as deposition technique in mechanical engineering

    Science.gov (United States)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  17. Sputtering. [as deposition technique in mechanical engineering

    Science.gov (United States)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  18. Generation of Articulated Mechanisms by Optimization Techniques

    DEFF Research Database (Denmark)

    Kawamoto, Atsushi

    2004-01-01

    that handles topological variations. In this thesis the technique is also extended so as to design the shape as well as the topology of the truss using cross-sectional areas and nodal positions as design variables. This leads to a technique for simultaneous type and dimensional synthesis of articulated...... optimization [Paper 2] 3. Branch and bound global optimization [Paper 3] 4. Path-generation problems [Paper 4] In terms of the objective of the articulated mechanism design problems, the first to third papers deal with maximization of output displacement, while the fourth paper solves prescribed path...... generation problems. From a mathematical programming point of view, the methods proposed in the first and third papers are categorized as deterministic global optimization, while those of the second and fourth papers are categorized as gradient-based local optimization. With respect to design variables, only...

  19. Kinetic activation-relaxation technique

    Science.gov (United States)

    Béland, Laurent Karim; Brommer, Peter; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand

    2011-10-01

    We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si (crystalline silicon), self-interstitial diffusion in Fe, and structural relaxation in a-Si (amorphous silicon).

  20. Kinetic activation-relaxation technique.

    Science.gov (United States)

    Béland, Laurent Karim; Brommer, Peter; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand

    2011-10-01

    We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si (crystalline silicon), self-interstitial diffusion in Fe, and structural relaxation in a-Si (amorphous silicon).

  1. SQL Injection Attacks: Techniques and Protection Mechanisms

    Directory of Open Access Journals (Sweden)

    Santosh Soni

    2011-01-01

    Full Text Available When an internet user interacts in web environment by surfing the Net, sending electronic mail messages and participating in online forums lot of data is generated which may have user’s private information. If this information is captured by third party tools and techniques; it may cause a breach in end user privacy. In the Web environment, end user privacy is one of the most controversial legal issues. In this paper issues related to information leakage through SQL injection attacks are presented and protection mechanisms are also discussed.

  2. Mechanical Design Optimization Using Advanced Optimization Techniques

    CERN Document Server

    Rao, R Venkata

    2012-01-01

    Mechanical design includes an optimization process in which designers always consider objectives such as strength, deflection, weight, wear, corrosion, etc. depending on the requirements. However, design optimization for a complete mechanical assembly leads to a complicated objective function with a large number of design variables. It is a good practice to apply optimization techniques for individual components or intermediate assemblies than a complete assembly. Analytical or numerical methods for calculating the extreme values of a function may perform well in many practical cases, but may fail in more complex design situations. In real design problems, the number of design parameters can be very large and their influence on the value to be optimized (the goal function) can be very complicated, having nonlinear character. In these complex cases, advanced optimization algorithms offer solutions to the problems, because they find a solution near to the global optimum within reasonable time and computational ...

  3. Dental adhesion: mechanism, techniques and durability.

    Science.gov (United States)

    Manuja, N; Nagpal, R; Pandit, I K

    2012-01-01

    Contemporary dental adhesives show favorable immediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. It appears that simplification of adhesive techniques is rather detrimental to the long-term stability of resin-tooth interface. The hydrostatic pulpal pressure, the dentinal fluid flow and the increased dentinal wetness in vital dentin can affect the intimate interaction of certain dentin adhesives with dentinal tissue. Bond degradation occurs via water sorption, hydrolysis of ester linkages of methacrylate resins, and activation of endogenous dentin matrix metalloproteinases. The three-step etch-and-rinse adhesives still remain the gold standard in terms of durability. This review discusses the fundamental process of adhesion to enamel and dentin with different adhesive techniques, factors affecting the long-term bonding performance of modern adhesives and addresses the current perspectives for improving bond durability.

  4. Development of Active Correlation Technique

    CERN Document Server

    Tsyganov, Y S

    2015-01-01

    With reaching to extremely high intensities of heavy-ion beams new requirements for the detection system of the Dubna Gas-Filled Recoil Separator (DGFRS) will definitely be set. One of the challenges is how to apply the active correlations method to suppress beam associated background products without significant losses in the whole long-term experiment efficiency value. Different scenarios and equations to develop the method according this requirement are under consideration in the present paper. The execution time to estimate the dead time parameter associated with the optimal choice of the life-time parameter is presented.

  5. Biofilms and mechanics: a review of experimental techniques and findings

    Science.gov (United States)

    Gordon, Vernita D.; Davis-Fields, Megan; Kovach, Kristin; Rodesney, Christopher A.

    2017-06-01

    Biofilms are developmentally-dynamic communities of sessile microbes that adhere to each other and, often, to other structures in their environment. The cohesive mechanical forces binding microbes to each other confer mechanical and structural stability on the biofilm and give rise to biofilm viscoelasticity. The adhesive mechanical forces binding microbes to other structures in their environment can promote biofilm initiation and mechanosensing that leads to changes in biological activity. Thus, physical mechanics is intrinsic to characteristics that distinguish biofilms from free-swimming or free-floating microbes in liquid culture. However, very little is known about the specifics of what mechanical traits characterize different types of biofilms at different stages of development. Even less is known about how mechanical inputs impact microbial biology and how microbes can adjust their mechanical coupling to, and interaction with, their environment. These knowledge gaps arise, in part, from the challenges associated with experimental measurements of microbial and biofilm biomechanics. Here, we review extant experimental techniques and their most-salient findings to date. At the end of this review we indicate areas where significant advances in the state-of-the art are heading.

  6. Jitter suppression techniques for mechanical cryocooler-induced disturbances

    Science.gov (United States)

    Wolfe, D. W.; Kirkconnell, C. S.; Fleischman, G. L.; Sunada, W. H.

    2008-08-01

    Closed-cycle mechanical cryogenic refrigerators, or cryocoolers, are an enabling technology for next generation infrared (IR) sensors. Passive cryoradiators and stored cryogen systems have been used successfully in the past, but the increased cooling requirements for emerging systems cannot practically be met with these passive techniques. Modern systems are employing much larger focal plane arrays that dissipate more energy and have higher parasitic thermal loads than in the past. Additional "on chip" FPA data processing capability, such as time delay and integration (TDI) and analog-to-digital conversion (ADC), is further driving up the heat loads. While loads are going up, temperatures are going down. The desire to operate at long wave infrared (LWIR) wavelengths (>9 microns) for a broader range of remote sensing missions is driving the need for 35-40 K refrigeration, significantly colder than past systems that operated at shorter wavelengths. Unfortunately, the use of a mechanical rather than passive cryocooler introduces an additional jitter source that must be properly mitigated. Techniques include the use of inherently low vibration cryocoolers, closedloop active vibration cancellation servo systems, damping struts, soft mounts, or a combination of these techniques. Implementation of these techniques within a proper system engineering context is presented.

  7. Multimedia Techniques To Teach Mechanical Skills.

    Science.gov (United States)

    Johns, Janet Faye; Brander, Julianne Marie

    1997-01-01

    Discusses the use of multimedia computer-based training to effectively teach mechanical skills. Gives an example of teaching shaft alignment tasks that combines three-dimensional animations, simulations, and user interactions to allow the trainee to practice recognition and manipulation skills. (Author/LRW)

  8. Fish Spoilage Mechanisms and Preservation Techniques: Review

    OpenAIRE

    Abdel E. Ghaly; Dave, D; Budge, S; M. S. Brooks

    2010-01-01

    Problem statement: Spoilage of food products is due to chemical, enzymatic or microbial activities One-fourth of the worlds food supply and 30% of landed fish are lost through microbial activity alone. With the ever growing world population and the need to store and transport the food from one place to another where it is needed, food preservation becomes necessary in order to increase its shelf life and maintain its nutritional value, texture and flavor. The freshness and quality of fish hav...

  9. Active learning techniques for librarians practical examples

    CERN Document Server

    Walsh, Andrew

    2010-01-01

    A practical work outlining the theory and practice of using active learning techniques in library settings. It explains the theory of active learning and argues for its importance in our teaching and is illustrated using a large number of examples of techniques that can be easily transferred and used in teaching library and information skills to a range of learners within all library sectors. These practical examples recognise that for most of us involved in teaching library and information skills the one off session is the norm, so we need techniques that allow us to quickly grab and hold our

  10. Meat Spoilage Mechanisms and Preservation Techniques: A Critical Review

    Directory of Open Access Journals (Sweden)

    D. Dave

    2011-01-01

    Full Text Available Problem statement: Extremely perishable meat provides favorable growth condition for various microorganisms. Meat is also very much susceptible to spoilage due to chemical and enzymatic activities. The breakdown of fat, protein and carbohydrates of meat results in the development of off-odors, off-flavor and slim formation which make the meat objectionable for human consumption. It is, therefore, necessary to control meat spoilage in order to increase its shelf life and maintain its nutritional value, texture and flavor. Approach: A comprehensive literature review was performed on the spoliage mechanisms of meat and meat products and preservation techniques. Results: Historical data reveals that salting, drying, smoking, fermentation and canning were the traditional methods used to prevent meat spoilage and extend its shelf life. However, in order to prevent wholesomeness, appearance, composition, tenderness, flavor, juiciness and nutritive value, new methods were developed. These included: cooling, freezing and chemical preservation. Wide range of physical and chemical reactions and actions of microorganisms or enzymes are responsible for the meat spoilage. Microbial growth, oxidation and enzymatic autolysis are three basic mechanisms responsible for spoilage of meat. Microbial growth and metabolism depends on various factors including: pre-slaughter husbandry practices, age of the animal at the time of slaughtering, handling during slaughtering, evisceration and processing, temperature controls during slaughtering, processing and distribution, preservation methods, type of packaging and handling and storage by consumer. Microbial spoilage causes pH change, slime formation, structural components degradation, off odors and appearance change. Autoxidation of lipids and the production of free radicals are natural processes which affect fatty acids and lead to oxidative deterioration of meat and off-flavour development. Lipid hydrolysis can take

  11. Testing techniques for mechanical characterization of rapidly solidified materials

    Science.gov (United States)

    Koch, C. C.

    1986-01-01

    Mechanical property testing techniques are reviewed for rapidly solidified materials. Mechanical testing of rapidly solidified materials is complicated by the fact that in most cases at least one dimension of the material is very small (less than 100 microns). For some geometries, i.e., powder or thin surface layers, microhardness is the only feasible mechanical test. The ribbon geometry which is obtained by the melt-spinning method, however, has been used for a variety of mechanical property measurements including elastic properties, tensile properties, fracture toughness, creep, and fatigue. These techniques are described with emphasis placed on the precautions required by the restricted geometry of rapidly solidified specimens.

  12. Efficacy of Manual and Mechanical Instrumentation Techniques for ...

    African Journals Online (AJOL)

    2016-02-29

    Feb 29, 2016 ... Efficacy of Manual and Mechanical Instrumentation Techniques for. Removal of .... hypochlorite (NaOCl) between the application of each file ..... Efficacy of automated versus hand instrumentation during root canal retreatment: ...

  13. Eigenspace design techniques for active flutter suppression

    Science.gov (United States)

    Garrard, W. L.; Liebst, B. S.

    1984-01-01

    The application of eigenspace design techniques to an active flutter suppression system for the DAST ARW-2 research drone is examined. Eigenspace design techniques allow the control system designer to determine feedback gains which place controllable eigenvalues in specified configurations and which shape eigenvectors to achieve desired dynamic response. Eigenspace techniques were applied to the control of lateral and longitudinal dynamic response of aircraft. However, little was published on the application of eigenspace techniques to aeroelastic control problems. This discussion will focus primarily on methodology for design of full-state and limited-state (output) feedback controllers. Most of the states in aeroelastic control problems are not directly measurable, and some type of dynamic compensator is necessary to convert sensor outputs to control inputs. Compensator design are accomplished by use of a Kalman filter modified if necessary by the Doyle-Stein procedure for full-state loop transfer function recovery, by some other type of observer, or by transfer function matching.

  14. New mechanism of lenalidomide activity.

    Science.gov (United States)

    Keevan, Jacob; Figg, William D

    2014-08-01

    Lenalidomide is an immunomodulatory agent (IMiD) that has activity in hematologic cancer (e.g., multiple myeloma). The immunomodulatory and apoptotic properties are readily apparent in therapy. However, the exact mechanism of action has been difficult to quantify until recently when it was shown that another IMiD, thalidomide, binds to an E3 ubiquitin ligase complex constituent, CRBN. The article by Kronke et al. demonstrates that, by binding to CRBN and altering its selectivity, lenalidomide potentiates the ubiquitination and proteolysis of 2 specific proteins, IKZF1 and IKZF3. An article in the same issue, by Lu et al., supports these observations. IKZF1 and IKZF3 are transcription factors that are necessary for multiple myeloma, and repression of these transcription factors is a likely mechanism for lenalidomide activity in this disease.

  15. Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

    Science.gov (United States)

    Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan; Liang, Guozheng

    2017-07-01

    Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO2 and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91-95%, about 29-14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and modified fibers. The excellent comprehensive properties of BL-AFs demonstrate that the green method provided in this study is facile and effective to completely solve the bottlenecks of aramid fibers, and developing higher performance organic fibers.

  16. INTERIM REPORT ON CONCRETE DEGRADATION MECHANISMS AND ONLINE MONITORING TECHNIQUES

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Sankaran; Agarwal, Vivek; Neal, Kyle; Kosson, David; Adams, Douglas

    2014-09-01

    The existing fleets of nuclear power plants in the United States have initial operating licenses of 40 years, though most these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. The online monitoring of concrete structure conducted under the Advanced Instrumentation, Information, and Control Technologies Pathway of the Light Water Reactor Sustainability program at Idaho National Laboratory will develop and demonstrate concrete structures health monitoring capabilities. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code margins of safety. Therefore, the structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. Through this research project, several national laboratories and Vanderbilt University proposes to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses available techniques and ongoing challenges in each of the four elements of the proposed framework with emphasis on degradation mechanisms and online monitoring techniques.

  17. Interim Report on Concrete Degradation Mechanisms and Online Monitoring Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Neal, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    The existing nuclear power plants in the United States have initial operating licenses of 40 years, though most of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. The research on online monitoring of concrete structures conducted under the Advanced Instrumentation, Information, and Control Systems Technologies Pathway of the Light Water Reactor Sustainability Program at Idaho National Laboratory will develop and demonstrate concrete structures health monitoring capabilities. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code margins of safety. Therefore, structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses available techniques and ongoing challenges in each of the four elements of the proposed framework with emphasis on degradation mechanisms and online monitoring techniques.

  18. Active load control techniques for wind turbines.

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.; Johnson, Scott J. (University of California, Davis, CA)

    2008-07-01

    This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

  19. Mechanical Hemostasis Techniques in Nonvariceal Upper Gastrointestinal Bleeding.

    Science.gov (United States)

    Brock, Andrew S; Rockey, Don C

    2015-07-01

    One of the most important advances in gastroenterology has been the use of endoscopic hemostasis techniques to control nonvariceal upper gastrointestinal bleeding, particularly when high-risk stigmata are present. Several options are available, including injection therapy, sprays/topical agents, electrocautery, and mechanical methods. The method chosen depends on the nature of the lesion and experience of the endoscopist. This article reviews the available mechanical hemostatic modalities. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Weed Identification Using An Automated Active Shape Matching (AASM) Technique

    DEFF Research Database (Denmark)

    Swain, K C; Nørremark, Michael; Jørgensen, R N

    2011-01-01

    Weed identification and control is a challenge for intercultural operations in agriculture. As an alternative to chemical pest control, a smart weed identification technique followed by mechanical weed control system could be developed. The proposed smart identification technique works...... on the concept of ‘active shape modelling’ to identify weed and crop plants based on their morphology. The automated active shape matching system (AASM) technique consisted of, i) a Pixelink camera ii) an LTI (Lehrstuhlfuer technische informatik) image processing library, iii) a laptop pc with the Linux OS. A 2......-leaf growth stage model for Solanum nigrum L. (nightshade) is generated from 32 segmented training images in Matlab software environment. Using the AASM algorithm, the leaf model was aligned and placed at the centre of the target plant and a model deformation process carried out. The parameters used...

  1. Mechanical Properties, Purifying Techniques and Processing Methods of Metal Yttrium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The mechanical properties of metal yttrium such as strength, plasticity, hardness and elasticity were introduced. The purifying techniques of yttrium were discussed in detail. The processing methods for metal yttrium including extruding, forging, rolling, wiredrawing and welding were also introduced. Finally, the potential use of yttrium and its alloys were prospected.

  2. Mechanism and active variety of allelochemicals

    Science.gov (United States)

    Peng, S.-L.; Wen, J.; Guo, Q.-F.

    2004-01-01

    This article summarizes allelochemicals' active variety, its potential causes and function mechanisms. Allelochemicals' activity varies with temperature, photoperiod, water and soils during natural processes, with its initial concentration, compound structure and mixed degree during functional processes, with plant accessions, tissues and maturity within-species, and with research techniques and operation processes. The prospective developmental aspects of allelopathy studies in the future are discussed. Future research should focus on: (1) to identify and purify allelochemicals more effectively, especially for agriculture, (2) the functions of allelopathy at the molecular structure level, (3) using allelopathy to explain plant species interactions, (4) allelopathy as a driving force of succession, and (5) the significance of allelopathy in the evolutionary processes.

  3. Study of mechanically activated coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Anatolij P. Burdukov; Vitalij A. Popov; Valentin A. Faleev [Institute of Thermophysics, Novosibirsk (Russian Federation)

    2009-07-01

    Combustion and air gasification of mechanically activated micro-ground coals in the flux have been studied. Influence of mechanically activated methods of coal grinding on their chemical activity at combustion and gasification has been determined. Intense mechanical activation of coals increases their chemical activity that enables development of new highly boosted processing methods for coals with various levels of metamorphism. 10 refs., 14 figs., 1 tab.

  4. Acoustic Emission Technique Applied in Textiles Mechanical Characterization

    Directory of Open Access Journals (Sweden)

    Rios-Soberanis Carlos Rolando

    2017-01-01

    Full Text Available The common textile architecture/geometry are woven, braided, knitted, stitch boded, and Z-pinned. Fibres in textile form exhibit good out-of-plane properties and good fatigue and impact resistance, additionally, they have better dimensional stability and conformability. Besides the nature of the textile, the architecture has a great role in the mechanical behaviour and mechanisms of damage in textiles, therefore damage mechanisms and mechanical performance in structural applications textiles have been a major concern. Mechanical damage occurs to a large extent during the service lifetime consequently it is vital to understand the material mechanical behaviour by identifying its mechanisms of failure such as onset of damage, crack generation and propagation. In this work, textiles of different architecture were used to manufacture epoxy based composites in order to study failure events under tensile load by using acoustic emission technique which is a powerful characterization tool due to its link between AE data and fracture mechanics, which makes this relation a very useful from the engineering point of view.

  5. Active cell mechanics: Measurement and theory.

    Science.gov (United States)

    Ahmed, Wylie W; Fodor, Étienne; Betz, Timo

    2015-11-01

    Living cells are active mechanical systems that are able to generate forces. Their structure and shape are primarily determined by biopolymer filaments and molecular motors that form the cytoskeleton. Active force generation requires constant consumption of energy to maintain the nonequilibrium activity to drive organization and transport processes necessary for their function. To understand this activity it is necessary to develop new approaches to probe the underlying physical processes. Active cell mechanics incorporates active molecular-scale force generation into the traditional framework of mechanics of materials. This review highlights recent experimental and theoretical developments towards understanding active cell mechanics. We focus primarily on intracellular mechanical measurements and theoretical advances utilizing the Langevin framework. These developing approaches allow a quantitative understanding of nonequilibrium mechanical activity in living cells. This article is part of a Special Issue entitled: Mechanobiology.

  6. Performance Comparison of Active Queue Management Techniques

    Directory of Open Access Journals (Sweden)

    T. B. Reddy

    2008-01-01

    Full Text Available Congestion is an important issue which researchers focus on in the Transmission Control Protocol (TCP network environment. To keep the stability of the whole network, congestion control algorithms have been extensively studied. Queue management method employed by the routers is one of the important issues in the congestion control study. Active Queue Management (AQM has been proposed as a router-based mechanism for early detection of congestion inside the network. In this study, we are comparing AQM two popular queue management methods, Random Early Detection (RED and droptail, in different aspects, such as throughput and fairness Index. The comparison results indicate RED performed slightly better with higher throughput and higher fairness Index than droptail. Simulation is done by using Network Simulator (NS2 and the graphs are drawn using X- graph.

  7. Assessing voluntary muscle activation with the twitch interpolation technique.

    Science.gov (United States)

    Shield, Anthony; Zhou, Shi

    2004-01-01

    stimuli. Sensitive twitch interpolation techniques have revealed small to moderate deficits in voluntary activation during brief maximal efforts and progressively increasing activation deficits (central fatigue) during exhausting exercise. A small number of recent studies suggest that resistance training may result in improved voluntary activation of the quadriceps femoris and ankle plantarflexor muscles but not the biceps brachii. A significantly larger body of evidence indicates that voluntary activation declines as a consequence of bed-rest, joint injury and joint degeneration. Twitch interpolation has also been employed to study the mechanisms by which caffeine and pseudoephedrine enhance exercise performance.

  8. Complementary home mechanical ventilation techniques. SEPAR Year 2014.

    Science.gov (United States)

    Chiner, Eusebi; Sancho-Chust, José N; Landete, Pedro; Senent, Cristina; Gómez-Merino, Elia

    2014-12-01

    This is a review of the different complementary techniques that are useful for optimizing home mechanical ventilation (HMV). Airway clearance is very important in patients with HMV and many patients, particularly those with reduced peak cough flow, require airway clearance (manual or assisted) or assisted cough techniques (manual or mechanical) and suctioning procedures, in addition to ventilation. In the case of invasive HMV, good tracheostomy cannula management is essential for success. HMV patients may have sleep disturbances that must be taken into account. Sleep studies including complete polysomnography or respiratory polygraphy are helpful for identifying patient-ventilator asynchrony. Other techniques, such as bronchoscopy or nutritional support, may be required in patients on HMV, particularly if percutaneous gastrostomy is required. Information on treatment efficacy can be obtained from HMV monitoring, using methods such as pulse oximetry, capnography or the internal programs of the ventilators themselves. Finally, the importance of the patient's subjective perception is reviewed, as this may potentially affect the success of the HMV. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

  9. Damage detection technique by measuring laser-based mechanical impedance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeonseok; Sohn, Hoon [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (Daehak-ro 291, Yuseong-gu, Daejeon 305-701) (Korea, Republic of)

    2014-02-18

    This study proposes a method for measurement of mechanical impedance using noncontact laser ultrasound. The measurement of mechanical impedance has been of great interest in nondestructive testing (NDT) or structural health monitoring (SHM) since mechanical impedance is sensitive even to small-sized structural defects. Conventional impedance measurements, however, have been based on electromechanical impedance (EMI) using contact-type piezoelectric transducers, which show deteriorated performances induced by the effects of a) Curie temperature limitations, b) electromagnetic interference (EMI), c) bonding layers and etc. This study aims to tackle the limitations of conventional EMI measurement by utilizing laser-based mechanical impedance (LMI) measurement. The LMI response, which is equivalent to a steady-state ultrasound response, is generated by shooting the pulse laser beam to the target structure, and is acquired by measuring the out-of-plane velocity using a laser vibrometer. The formation of the LMI response is observed through the thermo-mechanical finite element analysis. The feasibility of applying the LMI technique for damage detection is experimentally verified using a pipe specimen under high temperature environment.

  10. Using High Speed Smartphone Cameras and Video Analysis Techniques to Teach Mechanical Wave Physics

    Science.gov (United States)

    Bonato, Jacopo; Gratton, Luigi M.; Onorato, Pasquale; Oss, Stefano

    2017-01-01

    We propose the use of smartphone-based slow-motion video analysis techniques as a valuable tool for investigating physics concepts ruling mechanical wave propagation. The simple experimental activities presented here, suitable for both high school and undergraduate students, allows one to measure, in a simple yet rigorous way, the speed of pulses…

  11. [Molecular mechanisms regulating the activity of macrophages].

    Science.gov (United States)

    Onoprienko, L V

    2011-01-01

    This article reviews modern concepts of the most common types of macrophage activation: classical, alternative, and type II. Molecular mechanisms of induction and regulation of these three types of activation are discussed. Any population of macrophages was shown to change its properties depending on its microenvironment and concrete biological situation (the "functional plasticity of macrophages"). Many intermediate states of macrophages were described along with the most pronounced and well-known activation types (classical activation, alternative activation, and type II activation). These intermediate states are characterized by a variety of combinations of their biological properties, including elements of the three afore mentioned types of activation. Macrophage activity is regulated by a complex network of interrelated cascade mechanisms.

  12. Learning by Doing: An Empirical Study of Active Teaching Techniques

    Science.gov (United States)

    Hackathorn, Jana; Solomon, Erin D.; Blankmeyer, Kate L.; Tennial, Rachel E.; Garczynski, Amy M.

    2011-01-01

    The current study sought to examine the effectiveness of four teaching techniques (lecture, demonstrations, discussions, and in-class activities) in the classroom. As each technique offers different benefits to the instructor and students, each technique was expected to aid in a different depth of learning. The current findings indicated that each…

  13. Mechanism of phenol adsorption onto electro-activated carbon granules.

    Science.gov (United States)

    Lounici, H; Aioueche, F; Belhocine, D; Drouiche, M; Pauss, A; Mameri, N

    2004-01-01

    The main purpose of this paper is to determine the mechanisms which govern the adsorption of the phenol onto electro-activated carbon granules. This new activation technique allowed an increase of the performance of the adsorbent. Two models were utilised to understand the improvement in the performance of electroactivated carbon granules. The first, a simple external resistance model based on film resistance, gave acceptable predictions, with an error of less than 15%, between the theoretical results and experimental data independent of the activation potential and phenol initial concentration. The second linear model, based on diffusion phenomena, was more representative in describing the experiment than the first model. It was observed that the electro-activation method did not change the mechanism which governs phenol adsorption onto granular carbon. Indeed, the same mathematical model based on diffusion phenomena made it possible to predict with a very low error (less than 5%) the experimental data obtained for the favourable activation potential, without activation potential and with an unfavourable activation potential. The electro-activation technique makes it possible to increase the number of active sites that improve the performance of the electro-activated granular carbon compared with conventional granular activated carbon.

  14. [Molecular repair mechanisms using the Intratissue Percutaneous Electrolysis technique in patellar tendonitis].

    Science.gov (United States)

    Abat, F; Valles, S L; Gelber, P E; Polidori, F; Stitik, T P; García-Herreros, S; Monllau, J C; Sanchez-Ibánez, J M

    2014-01-01

    To investigate the molecular mechanisms of tissue response after treatment with the Intratissue Percutaneous Electrolysis (EPI(®)) technique in collagenase-induced tendinopathy in Sprague-Dawley rats. Tendinopathy was induced by injecting 50 μg of type i collagenase into the patellar tendon of 24 Sprague Dawley rats of 7 months of age and weighting 300 g. The sample was divided into 4 groups: the control group, collagenase group, and two EPI(®) technique treatment groups of 3 and 6 mA, respectively. An EPI(®) treatment session was applied, and after 3 days, the tendons were analysed using immunoblotting and electrophoresis techniques. An analysis was also made of cytochrome C protein, Smac/Diablo, vascular endothelial growth factor and its receptor 2, as well as the nuclear transcription factor peroxisome proliferator-activated receptor gamma. A statistically significant increase, compared to the control group, was observed in the expression of cytochrome C, Smac/Diablo, vascular endothelial growth factor, its receptor 2 and peroxisome proliferator-activated receptor gamma in the groups in which the EPI(®) technique was applied. EPI(®) technique produces an increase in anti-inflammatory and angiogenic molecular mechanisms in collagenase-induced tendon injury in rats. Copyright © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

  15. Chapter 8. Activation mechanisms of chemokine receptors

    DEFF Research Database (Denmark)

    Jensen, Pia C; Rosenkilde, Mette M

    2009-01-01

    Chemokine receptors belong to the large family of 7-transmembrane (7TM) G-protein-coupled receptors. These receptors are targeted and activated by a variety of different ligands, indicating that activation is a result of similar molecular mechanisms but not necessarily similar modes of ligand bin...

  16. Investigation of mechanical properties of pavement through electromagnetic techniques

    Science.gov (United States)

    Benedetto, Andrea; Tosti, Fabio; D'Amico, Fabrizio

    2014-05-01

    Ground-penetrating radar (GPR) is considered as one of the most flexible geophysical tools that can be effectively and efficiently used in many different applications. In the field of pavement engineering, GPR can cover a wide range of uses, spanning from physical to geometrical inspections of pavements. Traditionally, such inferred information are integrated with mechanical measurements from other traditional (e.g. plate bearing test) or non-destructive (e.g. falling weight deflectometer) techniques, thereby resulting, respectively, in time-consuming and low-significant measurements, or in a high use of technological resources. In this regard, the new challenge of retrieving mechanical properties of road pavements and materials from electromagnetic measurements could represent a further step towards a greater saving of economic resources. As far as concerns unpaved and bound layers it is well-known that strength and deformation properties are mostly affected, respectively, by inter-particle friction and cohesion of soil particles and aggregates, and by bitumen adhesion, whose variability is expressed by the Young modulus of elasticity. In that respect, by assuming a relationship between electromagnetic response (e.g. signal amplitudes) and bulk density of materials, a reasonable correlation between mechanical and electric properties of substructure is therefore expected. In such framework, a pulse GPR system with ground-coupled antennae, 600 MHz and 1600 MHz centre frequencies was used over a 4-m×30-m test site composed by a flexible pavement structure. The horizontal sampling resolution amounted to 2.4×10-2 m. A square regular grid mesh of 836 nodes with a 0.40-m spacing between the GPR acquisition tracks was surveyed. Accordingly, a light falling weight deflectometer (LFWD) was used for measuring the elastic modulus of pavement at each node. The setup of such instrument consisted of a 10-kg falling mass and a 100-mm loading plate so that the influence domain

  17. Orbital mechanics and astrodynamics techniques and tools for space missions

    CERN Document Server

    Hintz, Gerald R

    2015-01-01

    This textbook covers fundamental and advanced topics in orbital mechanics and astrodynamics to expose the student to the basic dynamics of space flight. The engineers and graduate students who read this class-tested text will be able to apply their knowledge to mission design and navigation of space missions. Through highlighting basic, analytic and computer-based methods for designing interplanetary and orbital trajectories, this text provides excellent insight into astronautical techniques and tools. This book is ideal for graduate students in Astronautical or Aerospace Engineering and related fields of study, researchers in space industrial and governmental research and development facilities, as well as researchers in astronautics. This book also: ·       Illustrates all key concepts with examples ·       Includes exercises for each chapter ·       Explains concepts and engineering tools a student or experienced engineer can apply to mission design and navigation of space missions ·�...

  18. Mechanical properties of ultra thin metallic films revealed by synchrotron techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Patric Alfons

    2007-07-20

    A prerequisite for the study of the scaling behavior of mechanical properties of ultra thin films is a suitable testing technique. Therefore synchrotron-based in situ testing techniques were developed and optimized in order to characterize the stress evolution in ultra thin metallic films on compliant polymer substrates during isothermal tensile tests. Experimental procedures for polycrystalline as well as single crystalline films were established. These techniques were used to systematically investigate the influence of microstructure, film thickness (20 to 1000 nm) and temperature (-150 to 200 C) on the mechanical properties. Passivated and unpassivated Au and Cu films as well as single crystalline Au films on polyimide substrates were tested. Special care was also dedicated to the microstructural characterization of the samples which was very important for the correct interpretation of the results of the mechanical tests. Down to a film thickness of about 100 to 200 nm the yield strength increased for all film systems (passivated and unpassivated) and microstructures (polycrystalline and singlecrystalline). The influence of different interfaces was smaller than expected. This could be explained by a dislocation source model based on the nucleation of perfect dislocations. For polycrystalline films the film thickness as well as the grain size distribution had to be considered. For smaller film thicknesses the increase in flow stress was weaker and the deformation behavior changed because the nucleation of perfect dislocations became unfavorable. Instead, the film materials used alternative mechanisms to relieve the high stresses. For regular and homogeneous deformation the total strain was accommodated by the nucleation and motion of partial dislocations. If the deformation was localized due to initial cracks in a brittle interlayer or local delamination, dislocation plasticity was not effective enough to relieve the stress concentration and the films showed

  19. Using high speed smartphone cameras and video analysis techniques to teach mechanical wave physics

    Science.gov (United States)

    Bonato, Jacopo; Gratton, Luigi M.; Onorato, Pasquale; Oss, Stefano

    2017-07-01

    We propose the use of smartphone-based slow-motion video analysis techniques as a valuable tool for investigating physics concepts ruling mechanical wave propagation. The simple experimental activities presented here, suitable for both high school and undergraduate students, allows one to measure, in a simple yet rigorous way, the speed of pulses along a spring and the period of transverse standing waves generated in the same spring. These experiments can be helpful in addressing several relevant concepts about the physics of mechanical waves and in overcoming some of the typical student misconceptions in this same field.

  20. Input techniques that dynamically change their cursor activation area

    DEFF Research Database (Denmark)

    Hertzum, Morten; Hornbæk, Kasper

    2007-01-01

    cursor, whose activation area always contains the closest object, and two variants of cell cursors, whose activation areas contain a set of objects in the vicinity of the cursor. We report two experiments that compare these techniques to a point cursor; in one experiment participants use a touchpad......Efficient pointing is crucial to graphical user interfaces, and input techniques that dynamically change their activation area may yield improvements over point cursors by making objects selectable at a distance. Input techniques that dynamically change their activation area include the bubble...... for operating the input techniques, in the other a mouse. In both experiments, the bubble cursor is fastest and participants make fewer errors with it. Participants also unanimously prefer this technique. For small targets, the cell cursors are generally more accurate than the point cursor; in the second...

  1. Working mechanism and numerical simulation of assembly coastal building techniques

    Institute of Scientific and Technical Information of China (English)

    陈育民; 刘汉龙; 陈泽

    2008-01-01

    A new coastal technique, named as assembly coastal building, was introduced. The main concept of the technique was the assembling components which could be combined and locked together to form a large caisson. The assembly coastal building technique was used in a sea access road in Zhuanghai 4X1 well, Dagang Oilfield. The design plans and in-situ tests in the sea access road project were introduced in detail. According to the Zhuanghai project, the numerical simulation method of assembly coastal building technique was proposed. 2D numerical simulations were performed in FLAC to analyze the displacement and stability of the technique in the construction process and post-construction period. The settlement calculated is close to the in-situ results, which proves that the proposed numerical method is reasonable. Results show that the assembly coastal building technique has large safety factor under the gravity loading and wave loadings.

  2. Barnacle muscle: Ca2+, activation and mechanics.

    Science.gov (United States)

    Ashley, C C; Griffiths, P J; Lea, T J; Mulligan, I P; Palmer, R E; Simnett, S J

    1993-01-01

    In this review, aspects of the ways in which Ca2+ is transported and regulated within muscle cells have been considered, with particular reference to crustacean muscle fibres. The large size of these fibres permits easy access to the internal environment of the cell, allowing it to be altered by microinjection or microperfusion. At rest, Ca2+ is not in equilibrium across the cell membrane, it enters the cell down a steep electrochemical gradient. The free [Ca2+] at rest is maintained at a value close to 200 nM by a combination of internal buffering systems, mainly the SR, mitochondria, and the fixed and diffusible Ca(2+)-binding proteins, as well as by an energy-dependent extrusion system operating across the external cell membrane. This system relies upon the inward movement of Na+ down its own electrochemical gradient to provide the energy for the extrusion of Ca2+ ions. As a result of electrical excitation, voltage-sensitive channels for Ca2+ are activated and permit Ca2+ to enter the cell more rapidly than at rest. It has been possible to determine both the amount of Ca2+ entering by this step, and what part this externally derived Ca2+ plays in the development of force as well as in the free Ca2+ change. The latter can be determined directly by Ca(2+)-sensitive indicators introduced into the cell sarcoplasm. A combination of techniques, allowing both the total and free Ca2+ changes to be assessed during electrical excitation, has provided valuable information as to how muscle cells buffer their Ca2+ in order to regulate the extent of the change in the free Ca2+ concentration. The data indicate that the entering Ca2+ can only make a small direct contribution to the force developed by the cell. The implication here is that the major source of Ca2+ for contraction must be derived from the internal Ca2+ storage sites within the SR system, a view reinforced by caged Ca2+ methods. The ability to measure the free Ca2+ concentration changes within a single cell during

  3. Competing activation mechanisms in epidemics on networks

    CERN Document Server

    Castellano, Claudio

    2011-01-01

    In stark contrast to previous common wisdom that epidemic activity and thresholds in heterogeneous networks are dominated by the elements with the largest number of connections (the hubs), recent research has pointed out the role of the most efficient spreaders, located at the innermost, dense core of the network, in sustaining epidemic processes. Here we show that the mechanism responsible of epidemic spreading depends on the dynamical pattern of the epidemic process. For epidemics with a transient state, activity is essentially boosted by the innermost core of the network. On the contrary, epidemics allowing a steady state present a dual scenario, where either the vertex with the largest connectivity independently sustains activity and propagates it to the rest of the system, or, alternatively, the innermost core of the network collectively turns into the active state, maintaining it on a global scale. Which one of these two mechanisms actually governs the dynamics depends on the network features. In uncorr...

  4. Particle fluence measurements by activation technique for radiation damage studies

    CERN Document Server

    León-Florián, E; Furetta, C; Leroy, Claude

    1995-01-01

    High-level radiation environment can produce radiation damage in detectors and their associate electronic components. The establishment of a correlation between damage, irradiation level and absorbed dose requires a precise measurement of the fluence of particles causing the damage. The activation technique is frequently used for performing particle fluence measurements. A review of this technique is presented.

  5. High frequency PMN-PT single crystal focusing transducer fabricated by a mechanical dimpling technique.

    Science.gov (United States)

    Chen, Y; Lam, K H; Zhou, D; Cheng, W F; Dai, J Y; Luo, H S; Chan, H L W

    2013-02-01

    High frequency (∼30MHz and ∼80MHz) focusing ultrasound transducers were fabricated using a PMN-0.28PT single crystal by a mechanical dimpling technique. The dimpled single crystal was used as an active element for the focusing transducer. Compared with a plane transducer, the focusing transducer fabricated with a dimpled active element exhibits much broader bandwidth and higher sensitivity. Besides, a high quality image can be obtained by the 30MHz focusing transducer, in which the -6dB axial and lateral resolution is 27μm and 139μm, respectively. These results prove that the dimpling technique is capable to fabricate the high frequency focusing transducers with excellent performance for imaging applications.

  6. Mechanisms of cell propulsion by active stresses

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, A E, E-mail: aec@wustl.edu [Department of Physics, Washington University, Campus Box 1105, One Brookings Drive, St. Louis, MO 63130 (United States)

    2011-07-15

    The mechanisms by which cytoskeletal flows and cell-substrate interactions interact to generate cell motion are explored by using a simplified model of the cytoskeleton as a viscous gel containing active stresses. This model yields explicit general results relating cell speed and traction forces to the distributions of active stress and cell-substrate friction. It is found that (i) the cell velocity is given by a function that quantifies the asymmetry of the active-stress distribution, (ii) gradients in cell-substrate friction can induce motion even when the active stresses are symmetrically distributed, (iii) the traction-force dipole is enhanced by protrusive stresses near the cell edges or contractile stresses near the center of the cell and (iv) the cell velocity depends biphasically on the cell-substrate adhesion strength if active stress is enhanced by adhesion. Specific experimental tests of the calculated dependences are proposed.

  7. Active cycle of breathing technique for cystic fibrosis.

    Science.gov (United States)

    Mckoy, Naomi A; Wilson, Lisa M; Saldanha, Ian J; Odelola, Olaide A; Robinson, Karen A

    2016-07-05

    People with cystic fibrosis experience chronic airway infections as a result of mucus build up within the lungs. Repeated infections often cause lung damage and disease. Airway clearance therapies aim to improve mucus clearance, increase sputum production, and improve airway function. The active cycle of breathing technique (also known as ACBT) is an airway clearance method that uses a cycle of techniques to loosen airway secretions including breathing control, thoracic expansion exercises, and the forced expiration technique. This is an update of a previously published review. To compare the clinical effectiveness of the active cycle of breathing technique with other airway clearance therapies in cystic fibrosis. We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews.Date of last search: 25 April 2016. Randomised or quasi-randomised controlled clinical studies, including cross-over studies, comparing the active cycle of breathing technique with other airway clearance therapies in cystic fibrosis. Two review authors independently screened each article, abstracted data and assessed the risk of bias of each study. Our search identified 62 studies, of which 19 (440 participants) met the inclusion criteria. Five randomised controlled studies (192 participants) were included in the meta-analysis; three were of cross-over design. The 14 remaining studies were cross-over studies with inadequate reports for complete assessment. The study size ranged from seven to 65 participants. The age of the participants ranged from six to 63 years (mean age 22.33 years). In 13 studies, follow up lasted a single day. However, there were two long-term randomised controlled studies with follow up of one to three years. Most of the studies did not report on key quality items, and therefore, have an unclear risk of

  8. Comets: mechanisms of x-ray activity

    Science.gov (United States)

    Ibadov, Subhon

    2016-07-01

    Basic mechanisms of X-ray activity of comets are considered, including D-D mechanism corresponding to generation of X-rays due to production of hot short-living plasma clumps at high-velocity collisions between cometary and interplanetary dust particles as well as M-M one corresponding to production of X-rays due to recombination of multicharge ions of solar wind plasma via charge exchange process at their collisions with molecules/atoms of the cometary atmospheres. Peculiarities of the variation of the comet X-ray spectrum and X-ray luminosity with variation of its heliocentric distance are revealed.

  9. Electrochemical mechanical micromachining based on confined etchant layer technique.

    Science.gov (United States)

    Yuan, Ye; Han, Lianhuan; Zhang, Jie; Jia, Jingchun; Zhao, Xuesen; Cao, Yongzhi; Hu, Zhenjiang; Yan, Yongda; Dong, Shen; Tian, Zhong-Qun; Tian, Zhao-Wu; Zhan, Dongping

    2013-01-01

    The confined etchant layertechnique (CELT) has been proved an effective electrochemical microfabrication method since its first publication at Faraday Discussions in 1992. Recently, we have developed CELT as an electrochemical mechanical micromachining (ECMM) method by replacing the cutting tool used in conventional mechanical machining with an electrode, which can perform lathing, planing and polishing. Through the coupling between the electrochemically induced chemical etching processes and mechanical motion, ECMM can also obtain a regular surface in one step. Taking advantage of CELT, machining tolerance and surface roughness can reach micro- or nano-meter scale.

  10. Talking Techne: Techniques to Establish an Active Online Discussion Forum

    Science.gov (United States)

    Palenque, Stephanie Maher; DeCosta, Meredith

    2015-01-01

    Discussion forums are critically important to the online classroom, as they virtually take the place of a classroom discussion and become a stage on which active learning takes place. Active learning occurs when instructors practice certain techniques in the discussion that are carefully and thoughtfully crafted and guided. The authors propose the…

  11. NIFS workshop on application of micro-indentation technique to evaluation of mechanical properties of fusion materials. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Kurishita, Hiroaki; Katoh, Yutai [eds.] [Tohoku Univ., Oarai, Ibaraki (Japan). Oarai Branch, Inst. for Materials Research

    1996-11-01

    NIFS workshop on `Application of Micro-Indentation Technique to Evaluation of Mechanical Properties of Fusion Materials` were help in Toki on October 9, 1996, as a part of the activity of NIFS collaborative research on `Advanced Technologies for Small-Volume Mechanical Property Testing of Fusion Reactor Materials`. The major topics at the workshop included the application of micro- (and nano-) indentation technique to evaluation of tensile stress-strain property, interfacial mechanical property of composite and joining materials and hardening of this layers in ion-irradiated materials. This report compiles the abstract and viewgraphs for each presentation. (author)

  12. Topological mechanics: from metamaterials to active matter

    Science.gov (United States)

    Vitelli, Vincenzo

    2015-03-01

    Mechanical metamaterials are artificial structures with unusual properties, such as negative Poisson ratio, bistability or tunable acoustic response, which originate in the geometry of their unit cell. At the heart of such unusual behavior is often a mechanism: a motion that does not significantly stretch or compress the links between constituent elements. When activated by motors or external fields, these soft motions become the building blocks of robots and smart materials. In this talk, we discuss topological mechanisms that possess two key properties: (i) their existence cannot be traced to a local imbalance between degrees of freedom and constraints (ii) they are robust against a wide range of structural deformations or changes in material parameters. The continuum elasticity of these mechanical structures is captured by non-linear field theories with a topological boundary term similar to topological insulators and quantum Hall systems. We present several applications of these concepts to the design and experimental realization of 2D and 3D topological structures based on linkages, origami, buckling meta-materials and lastly active media that break time-reversal symmetry.

  13. Mechanically activated artificial cell by using microfluidics.

    Science.gov (United States)

    Ho, Kenneth K Y; Lee, Lap Man; Liu, Allen P

    2016-01-01

    All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology.

  14. Mechanically activated artificial cell by using microfluidics

    Science.gov (United States)

    Ho, Kenneth K. Y.; Lee, Lap Man; Liu, Allen P.

    2016-09-01

    All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology.

  15. Mechanically activated artificial cell by using microfluidics

    Science.gov (United States)

    Ho, Kenneth K. Y.; Lee, Lap Man; Liu, Allen P.

    2016-01-01

    All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology. PMID:27610921

  16. Siquieros accidental painting technique: a fluid mechanics point of view

    CERN Document Server

    Zetina, Sandra

    2012-01-01

    This is an entry for the Gallery of Fluid Motion of the 65th Annual Meeting of the APS-DFD (fluid dynamics video). This video shows an analysis of the 'accidental painting' technique developed by D.A. Siqueiros, a famous Mexican muralist. We reproduced the technique that he used: pouring layers of paint of different colors on top of each other. We found that the layers mix, creating aesthetically pleasing patterns, as a result of a Rayleigh-Taylor instability. Due to the pigments used to give paints their color, they can have different densities. When poured on top of each other, if the top layer is denser than the lower one, the viscous gravity current undergoes unstable as it spread radially. We photograph the process and produced slowed-down video to visualize the process.

  17. PMN-PT single crystal focusing transducer fabricated using a mechanical dimpling technique.

    Science.gov (United States)

    Lam, K H; Chen, Y; Cheung, K F; Dai, J Y

    2012-01-01

    A ∼5MHz focusing PMN-PT single crystal ultrasound transducer has been fabricated utilizing a mechanical dimpling technique, where the dimpled crystal wafer was used as an active element of the focusing transducer. For the dimpled focusing transducer, the effective electromechanical coupling coefficient was enhanced significantly from 0.42 to 0.56. The dimpled transducer also yields a -6dB bandwidth of 63.5% which is almost double the bandwidth of the plane transducer. An insertion loss of the dimpled transducer (-18.1dB) is much lower than that of the plane transducer. Finite element simulation also reveals specific focused beam from concave crystal surface. These promising results show that the dimpling technique can be used to develop high-resolution focusing single crystal transducers.

  18. Copper chemical mechanical polishing using a slurry-free technique

    NARCIS (Netherlands)

    Nguyen, V.H.; Hof, A.J.; Kranenburg, van H.; Woerlee, P.H.; Weimar, F.

    2001-01-01

    A study of the chemical mechanical polishing (CMP) of thin copper films using fixed-abrasive pads is presented. The composition of the polishing solution is optimized by investigating the impact of both the oxidizer concentration and the pH of the solution on the polishing characteristics of copper.

  19. Mechanism of FGF receptor dimerization and activation

    Science.gov (United States)

    Sarabipour, Sarvenaz; Hristova, Kalina

    2016-01-01

    Fibroblast growth factors (fgfs) are widely believed to activate their receptors by mediating receptor dimerization. Here we show, however, that the FGF receptors form dimers in the absence of ligand, and that these unliganded dimers are phosphorylated. We further show that ligand binding triggers structural changes in the FGFR dimers, which increase FGFR phosphorylation. The observed effects due to the ligands fgf1 and fgf2 are very different. The fgf2-bound dimer structure ensures the smallest separation between the transmembrane (TM) domains and the highest possible phosphorylation, a conclusion that is supported by a strong correlation between TM helix separation in the dimer and kinase phosphorylation. The pathogenic A391E mutation in FGFR3 TM domain emulates the action of fgf2, trapping the FGFR3 dimer in its most active state. This study establishes the existence of multiple active ligand-bound states, and uncovers a novel molecular mechanism through which FGFR-linked pathologies can arise.

  20. Escherichia coli activity characterization using a laser dynamic speckle technique

    CERN Document Server

    Ramírez-Miquet, Evelio E; Contreras-Alarcón, Orestes R

    2012-01-01

    The results of applying a laser dynamic speckle technique to characterize bacterial activity are presented. The speckle activity was detected in two-compartment Petri dishes. One compartment was inoculated and the other one was left as a control blank. The speckled images were processed by the recently reported temporal difference method. Three inoculums of 0.3, 0.5, and 0.7 McFarland units of cell concentration were tested; each inoculum was tested twice for a total of six experiments. The dependences on time of the mean activity, the standard deviation of activity and other descriptors of the speckle pattern evolution were calculated for both the inoculated compartment and the blank. In conclusion the proposed dynamic speckle technique allows characterizing the activity of Escherichia coli bacteria in solid medium.

  1. Mechanism of chemical activation of Nrf2.

    Directory of Open Access Journals (Sweden)

    Yun Li

    Full Text Available NF-E2 related factor-2 (Nrf2 promotes the transcription of many cytoprotective genes and is a major drug target for prevention of cancer and other diseases. Indeed, the cancer-preventive activities of several well-known chemical agents were shown to depend on Nrf2 activation. It is well known that chemopreventive Nrf2 activators stabilize Nrf2 by blocking its ubiquitination, but previous studies have indicated that this process occurs exclusively in the cytoplasm. Kelch-like ECH-associated protein 1 (Keap1 binds to Nrf2 and orchestrates Nrf2 ubiquitination, and it has been a widely-held view that inhibition of Nrf2 ubiquitination by chemopreventive agents results from the dissociation of Nrf2 from its repressor Keap1. Here, we show that while the activation of Nrf2 by prototypical chemical activators, including 5,6-dihydrocyclopenta-1,2-dithiole-3-thione (CPDT and sulforaphane (SF, results solely from inhibition of its ubiquitination, such inhibition occurs predominantly in the nucleus. Moreover, the Nrf2 activators promote Nrf2 association with Keap1, rather than disassociation, which appears to result from inhibition of Nrf2 phosphorylation at Ser40. Available evidence suggests the Nrf2 activators may block Nrf2 ubiquitination by altering Keap1 conformation via reaction with the thiols of specific Keap1 cysteines. We further show that while the inhibitory effects of CPDT and SF on Nrf2 ubiquitination depend entirely on Keap1, Nrf2 is also degraded by a Keap1-independent mechanism. These findings provide significant new insight about Nrf2 activation and suggest that exogenous chemical activators of Nrf2 enter the nucleus to exert most of their inhibitory impact on Nrf2 ubiquitination and degradation.

  2. Shaping Neuronal Network Activity by Presynaptic Mechanisms.

    Directory of Open Access Journals (Sweden)

    Ayal Lavi

    2015-09-01

    Full Text Available Neuronal microcircuits generate oscillatory activity, which has been linked to basic functions such as sleep, learning and sensorimotor gating. Although synaptic release processes are well known for their ability to shape the interaction between neurons in microcircuits, most computational models do not simulate the synaptic transmission process directly and hence cannot explain how changes in synaptic parameters alter neuronal network activity. In this paper, we present a novel neuronal network model that incorporates presynaptic release mechanisms, such as vesicle pool dynamics and calcium-dependent release probability, to model the spontaneous activity of neuronal networks. The model, which is based on modified leaky integrate-and-fire neurons, generates spontaneous network activity patterns, which are similar to experimental data and robust under changes in the model's primary gain parameters such as excitatory postsynaptic potential and connectivity ratio. Furthermore, it reliably recreates experimental findings and provides mechanistic explanations for data obtained from microelectrode array recordings, such as network burst termination and the effects of pharmacological and genetic manipulations. The model demonstrates how elevated asynchronous release, but not spontaneous release, synchronizes neuronal network activity and reveals that asynchronous release enhances utilization of the recycling vesicle pool to induce the network effect. The model further predicts a positive correlation between vesicle priming at the single-neuron level and burst frequency at the network level; this prediction is supported by experimental findings. Thus, the model is utilized to reveal how synaptic release processes at the neuronal level govern activity patterns and synchronization at the network level.

  3. Evaluation of mechanical abuse techniques in lithium ion batteries

    Science.gov (United States)

    Lamb, Joshua; Orendorff, Christopher J.

    2014-02-01

    Mechanical tests are a commonly used method for evaluating the safety performance of batteries. The mechanical blunt rod testing method, as well as sharp nail penetration, was performed on commercially available cells. Evaluation was carried out on different cell constructions as well as varying test conditions. Results obtained at ambient conditions were found to differ little from traditional sharp nail penetration testing. When tested at elevated temperatures it was observed that the results became heavily dependent upon the internal construction of the cell. Computed Tomography (CT) imaging confirmed this, showing differences in behavior depending on whether or not a solid core was used in the cylindrical cell construction. Pouch cells were tested as well, showing that a full penetration of the cell was necessary to initiate a failure event within the cell.

  4. Activities of the Institute for Mechanical Engineering

    Science.gov (United States)

    The Institute of Mechanical Engineering (IME) is part of Canada's National Research Council. Its mission is to undertake, support, promote, and disseminate research and development in the mechanical engineering aspects of three vital sectors of the Canadian economy: transportation, resource industries, and manufacturing. The IME achieves its mission by performing research and development in its own facilities; by developing, providing, and transferring expertise and knowledge; by making its research facilities available to collaborators and clients; and by participating in international liaison and collaborative research activities. Six research programs are conducted in the IME: Advanced Manufacturing Technology; Coastal Zone Engineering; Cold Regions Engineering; Combustion and Fluids Engineering; Ground Transportation Technology; and Machinery and Engine Technology. The rationale and major research thrusts of each program are described, and specific achievements in 1991-92 are reviewed. Lists of technical reports and papers presented by IME personnel are also included.

  5. Evaluation of Mechanical Modal Characteristics Using Optical Techniques

    Science.gov (United States)

    Lekki, John; Adamovsky, Grigory; Flanagan, Patrick; Weiland, Ken

    2002-01-01

    In this paper the sensitivity of embedded fiber optic sensors to changes in modal characteristics of plates is discussed. In order to determine the feasibility of embedded fiber Bragg gratings for the detection of modal shapes and modal frequencies, a comparison of holographically imaged modes and the detected dynamic strain from embedded fiber optic Bragg gratings is made. Time averaged optical holography is used for the detection of mechanical defects, or damage, in various aerospace components. The damage is detected by measuring an alteration in structural dynamics, which is visually apparent when using time-averaged holography. These shifts in the mode shapes, both in frequency of the resonance and spatial location of vibration nodes, are caused by changes in parameters that affect the structure's mechanical impedance, such as stiffness, mass and damping, resulting from cracks or holes. It is anticipated that embedded fiber optic sensor arrays may also be able to detect component damage by sensing these changes in modal characteristics. This work is designed to give an initial indication to the feasibility of damage detection through the monitoring of modal frequencies and mode shapes with fiber optic sensors.

  6. Robust control design techniques for active flutter suppression

    Science.gov (United States)

    Ozbay, Hitay; Bachmann, Glen R.

    1994-01-01

    In this paper, an active flutter suppression problem is studied for a thin airfoil in unsteady aerodynamics. The mathematical model of this system is infinite dimensional because of Theodorsen's function which is irrational. Several second order approximations of Theodorsen's function are compared. A finite dimensional model is obtained from such an approximation. We use H infinity control techniques to find a robustly stabilizing controller for active flutter suppression.

  7. Electrical properties of mechanically activated zinc oxide

    Directory of Open Access Journals (Sweden)

    Vojisavljević K.

    2006-01-01

    Full Text Available Microstructural properties of a commercial zinc oxide powder were modified by mechanical activation in a high-energy vibro-mill. The obtained powders were dry pressed and sintered at 1100°C for 2 h. The electrical properties of grain boundaries of obtained ZnO ceramics were studied using an ac impedance analyzer. For that purpose, the ac electrical response was measured in the temperature range from 23 to 240°C in order to determine the resistance and capacitance of grain boundaries. The activation energies of conduction were obtained using an Arrhenius equation. Donor densities were calculated from Mott-Schottky measurements. The influence of microstructure, types and concentrations of defects on electrical properties was discussed.

  8. A comparison of maximal bioenergetic enzyme activities obtained with commonly used homogenization techniques.

    Science.gov (United States)

    Grace, M; Fletcher, L; Powers, S K; Hughes, M; Coombes, J

    1996-12-01

    Homogenization of tissue for analysis of bioenergetic enzyme activities is a common practice in studies examining metabolic properties of skeletal muscle adaptation to disease, aging, inactivity or exercise. While numerous homogenization techniques are in use today, limited information exists concerning the efficacy of specific homogenization protocols. Therefore, the purpose of this study was to compare the efficacy of four commonly used approaches to homogenizing skeletal muscle for analysis of bioenergetic enzyme activity. The maximal enzyme activity (Vmax) of citrate synthase (CS) and lactate dehydrogenase (LDH) were measured from homogenous muscle samples (N = 48 per homogenization technique) and used as indicators to determine which protocol had the highest efficacy. The homogenization techniques were: (1) glass-on-glass pestle; (2) a combination of a mechanical blender and a teflon pestle (Potter-Elvehjem); (3) a combination of the mechanical blender and a biological detergent; and (4) the combined use of a mechanical blender and a sonicator. The glass-on-glass pestle homogenization protocol produced significantly higher (P < 0.05) enzyme activities compared to all other protocols for both enzymes. Of the four protocols examined, the data demonstrate that the glass-on-glass pestle homogenization protocol is the technique of choice for studying bioenergetic enzyme activity in skeletal muscle.

  9. Bonding techniques for hybrid active pixel sensors (HAPS)

    Science.gov (United States)

    Bigas, M.; Cabruja, E.; Lozano, M.

    2007-05-01

    A hybrid active pixel sensor (HAPS) consists of an array of sensing elements which is connected to an electronic read-out unit. The most used way to connect these two different devices is bump bonding. This interconnection technique is very suitable for these systems because it allows a very fine pitch and a high number of I/Os. However, there are other interconnection techniques available such as direct bonding. This paper, as a continuation of a review [M. Lozano, E. Cabruja, A. Collado, J. Santander, M. Ullan, Nucl. Instr. and Meth. A 473 (1-2) (2001) 95-101] published in 2001, presents an update of the different advanced bonding techniques available for manufacturing a hybrid active pixel detector.

  10. A Technique for Shunt Active Filter meld micro grid System

    Directory of Open Access Journals (Sweden)

    A. Lumani

    2015-08-01

    Full Text Available The proposed system presents a control technique for a micro grid connected hybrid generation system ith case study interfaced with a three phase shunt active filter to suppress the current harmonics and reactive power present in the load using PQ Theory with ANN controller. This Hybrid Micro Grid is developed using freely renewable energy resources like Solar Photovoltaic (SPV and Wind Energy (WE. To extract the maximum available power from PV panels and wind turbines, Maximum power point Tracker (MPPT has been included. This MPPT uses the “Standard Perturbs and Observe” technique. By using PQ Theory with ANN Controller, the Reference currents are generated which are to be injected by Shunt active power filter (SAPFto compensate the current harmonics in the non linear load. Simulation studies shows that the proposed control technique performs non-linear load current harmonic compensation maintaining the load current in phase with the source voltage.\\

  11. Active structural control with stable fuzzy PID techniques

    CERN Document Server

    Yu, Wen

    2016-01-01

    This book presents a detailed discussion of intelligent techniques to measure the displacement of buildings when they are subjected to vibration. It shows how these techniques are used to control active devices that can reduce vibration 60–80% more effectively than widely used passive anti-seismic systems. After introducing various structural control devices and building-modeling and active structural control methods, the authors propose offset cancellation and high-pass filtering techniques to solve some common problems of building-displacement measurement using accelerometers. The most popular control algorithms in industrial settings, PD/PID controllers, are then analyzed and then combined with fuzzy compensation. The stability of this combination is proven with standard weight-training algorithms. These conditions provide explicit methods for selecting PD/PID controllers. Finally, fuzzy-logic and sliding-mode control are applied to the control of wind-induced vibration. The methods described are support...

  12. Meat Spoilage Mechanisms and Preservation Techniques: A Critical Review

    OpenAIRE

    D. Dave; Abdel E. Ghaly

    2011-01-01

    Problem statement: Extremely perishable meat provides favorable growth condition for various microorganisms. Meat is also very much susceptible to spoilage due to chemical and enzymatic activities. The breakdown of fat, protein and carbohydrates of meat results in the development of off-odors, off-flavor and slim formation which make the meat objectionable for human consumption. It is, therefore, necessary to control meat spoilage in order to increase its shelf life and maintain its nutrition...

  13. Innovative Perceptual Motor Activities: Programing Techniques That Work.

    Science.gov (United States)

    Sorrell, Howard M.

    1978-01-01

    A circuit approach and station techniques are used to depict perceptual motor games for handicapped and nonhandicapped children. Twenty activities are described in terms of objectives, materials, and procedures, and their focus on visual tracking, visual discrimination and copying of forms, spatial body perception, fine motor coordination, tactile…

  14. Novel platinum black electroplating technique improving mechanical stability.

    Science.gov (United States)

    Kim, Raeyoung; Nam, Yoonkey

    2013-01-01

    Platinum black microelectrodes are widely used as an effective neural signal recording sensor. The simple fabrication process, high quality signal recording and proper biocompatibility are the main advantages of platinum black microelectrodes. When microelectrodes are exposed to actual biological system, various physical stimuli are applied. However, the porous structure of platinum black is vulnerable to external stimuli and destroyed easily. The impedance level of the microelectrode increases when the microelectrodes are damaged resulting in decreased recording performance. In this study, we developed mechanically stable platinum black microelectrodes by adding polydopamine. The polydopamine layer was added between the platinum black structures by electrodeposition method. The initial impedance level of platinum black only microelectrodes and polydopamine added microelectrodes were similar but after applying ultrasonication the impedance value dramatically increased for platinum black only microelectrodes, whereas polydopamine added microelectrodes showed little increase which were nearly retained initial values. Polydopamine added platinum black microelectrodes are expected to extend the availability as neural sensors.

  15. Fine coal dewatering enhancement using mechanical thermal techniques

    Energy Technology Data Exchange (ETDEWEB)

    Patwardhan, A.; Mondal, K.; Chugh, Y.P.; Ping, H.; Singh, N. [Southern Illinois University-Carbondale, Carbondale, IL (USA). Department of Mining & Mineral Resources Engineering

    2002-07-01

    Studies were conducted in a laboratory pressure filter to evaluate and enhance the dewatering potential of thickener underflow samples from two operating coal mines in Illinois mining the No. 6 and No. 5 seams. Physical properties such as, size distribution, zeta potential variation with pH, microstructure and particle shape and ash content were characterized. In addition cake microstructure data was obtained through scanning electron microscopy. Experiments were conducted at a pressure of 42 psig. The initial solids content was varied from 8 to 30% to determine the impact of initial solids concentration on dewatering performance. A host of chemical treatments involving different surfactants and electrolytes were evaluated. In addition, mechanical agitation of cake and hot water treatment of the slurry was attempted. The introduction of copper ions into the slurry resulted in enhanced filtration rates due to reduced specific resistance to filtrate flow and increased porosity of the cake. Use of cationic and anionic surfactants reduced the total residual moisture by over 4%. The combined effect of a surfactant and copper ion resulted in further reduction in cake moisture along with significant improvement in dewatering rates. Elevating the temperature of the slurry to 55{degree}C showed only a slight improvement in filtration rate but produced the most compact cake with the lowest moisture content. Significant improvement in the dewatering kinetics from addition of electrolytes was also observed for the Illinois No. 5 seam sample. Statistical analysis of experimental data indicates dewatering enhancements as a result of electrolyte addition, hot water treatment and mechanical agitation. 20 refs., 5 figs., 7 tabs.

  16. Mechanical Micronization of Lipoaspirates: Squeeze and Emulsification Techniques.

    Science.gov (United States)

    Mashiko, Takanobu; Wu, Szu-Hsien; Feng, Jingwei; Kanayama, Koji; Kinoshita, Kaori; Sunaga, Ataru; Narushima, Mitsunaga; Yoshimura, Kotaro

    2017-01-01

    Condensation of grafted fat has been considered a key for achieving better outcomes after fat grafting. The authors investigated the therapeutic potential of two mechanical tissue micronizing procedures: squeeze and emulsification. Human aspirated fat was centrifuged (centrifuged fat) and fragmented with an automated slicer (squeezed fat). Alternatively, centrifuged fat was emulsified by repeated transfer between two syringes through a small-hole connecter and then separated by mesh filtration into two portions: residual tissue of emulsified fat and filtrated fluid of emulsified fat. The four products were examined for cellular components. Histologic and electron microscopic analyses revealed that squeezed fat and residual tissue of emulsified fat contained broken adipocytes and fragmented capillaries. Compared with centrifuged fat, the squeezed fat and residual fat products exhibited increased specific gravity and increased numbers of adipose-derived stem/stromal cells and endothelial cells per volume, suggesting successful cell/tissue condensation in both squeezed fat and residual tissue of emulsified fat. Although cell number and viability in the stromal vascular fraction were well maintained in both squeezed fat and residual fat, stromal vascular fraction culture assay showed that adipose-derived stromal cells were relatively damaged in residual tissue of emulsified fat but not in squeezed fat. By contrast, no adipose-derived stromal cells were cultured from filtrated fluid of emulsified fat. The authors' results demonstrated that mechanical micronization is easily conducted as a minimal manipulation procedure, which can condense the tissue by selectively removing adipocytes without damaging key components, such as adipose-derived stromal cells and endothelial cells. Depending on the extent of adipocyte removal, the product may be a useful therapeutic tool for efficient tissue volumization or therapeutic revitalization/fertilization. Therapeutic, V.

  17. The mechanism of phospholipase Cγ1 activation

    Directory of Open Access Journals (Sweden)

    Paweł Krawczyk

    2011-08-01

    Full Text Available Phospholipase C is an enzyme which catalyzes the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PI(4,5P2 into second messengers inositol-1,4,5-triphosphate (Ins(1,4,5P3 and diacylglycerol (DAG. These messengers then promote the activation of protein kinase C and release of Ca2 from intracellular stores, initiating numerous cellular events including proliferation, differentiation, signal transduction, endocytosis, cytoskeletal reorganization or activation of ion channels. There have been identified 14 isozymes of PLC among which PLCγ1 and PLCγ2 are of particular interest. PLC contains catalytic region XY and a few regulatory domains: PH, EF and C2. The most unique features of these two enzymes are the Src homology domains (SH2, SH3 and split PH domain within the catalytic barrel. PLC1 and PLCγ2 have an identical domain structure, but they differ in their function and occurrence. Phospholipase Cγ1 is expressed ubiquitously, especially in the brain, thymus and lungs.PLCγ1 can be activated by receptor tyrosine kinases (i.e.: PDGFR, EGFR, FGFR, Trk, as well as non-receptor protein kinases (Src, Syk, Tec or phosphatidic acid, tau protein and its analogue.The molecular mechanism of PLCγ1 activation includes membrane recruitment, phosphorylation, rearrangements and activation in the presence of growth factors.In reference to PLCγ1 regulation, a number of positive and negative modulators have been considered. The most important positive modulator is phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5P2. Protein kinase A and C, tyrosine phosphatases (SHP-1, PTP-1B and Cbl, Grb2, Jak2/PTP-1B complex proteins have been described as negative regulators of PLCγ1 activation.

  18. Advantages to Indigo mechanical thrombectomy for ALI: device and technique.

    Science.gov (United States)

    Yamada, R; Adams, J; Guimaraes, M; Schönholz, C

    2015-06-01

    Catheter-directed thrombolysis (CDT) has been used as the first therapeutic option for acute limb ischemia (ALI) due to its less invasive nature; however, recent systematic review showed higher incidence of major complications related to lytic infusion, including hemorrhagic stroke. In this setting, aspiration thrombectomy with Indigo has the greatest advantage of not increasing systemic risk of bleeding. The Indigo™ system from Penumbra® (Alameda, CA, USA) promotes active thrombectomy using a vacuum pump that generates substantial suction, enabling aspiration of clots of varying sizes and lengths. The device has three components: aspiration catheter, separator and pump. There are 2 aspiration catheter sizes: CAT 3 and CAT 5. The separators are intended to mobilize the clot and clean the catheter lumen, and therefore restoring flow for continuous aspiration. The pump is small-sized equipment capable of applying near pure vacuum aspiration pressure of -29 mmHg. Aspiration thrombectomy with Indigo has two key advantages: it does not require the use of lytics, and it provides immediate flow reestablishment. Its use when thrombolysis is contraindicated or has failed is already well established and, in the future, it may likely become the first line endovascular option in patients with acute limb ischemia.

  19. Techniques for Surveying Urban Active Faults by Seismic Methods

    Institute of Scientific and Technical Information of China (English)

    Xu Mingcai; Gao Jinghua; Liu Jianxun; Rong Lixin

    2005-01-01

    Using the seismic method to detect active faults directly below cities is an irreplaceable prospecting technique. The seismic method can precisely determine the fault position. Seismic method itself can hardly determine the geological age of fault. However, by considering in connection with the borehole data and the standard geological cross-section of the surveyed area, the geological age of reflected wave group can be qualitatively (or semi-quantitatively)determined from the seismic depth profile. To determine the upper terminal point of active faults directly below city, it is necessary to use the high-resolution seismic reflection technique.To effectively determine the geometric feature of deep faults, especially to determine the relation between deep and shallow fracture structures, the seismic reflection method is better than the seismic refraction method.

  20. Application of neutron activation tracer sediment technique on environmental science

    Institute of Scientific and Technical Information of China (English)

    YinYi; ZhongWei-Ni; 等

    1997-01-01

    Field and laboratory inverstigations were carried out to study the transport and dispersion law of polluted sediments near wastewater outlet using neutron activation tracer technique.The direction of transport and dispersion of polluted sediments,dispersion amount in different directions,sedimentary region of polluted sediment and evaluation of polluted risk are given.This provided a new test method for the study of environmental science and added a new forecasted content for the evaluation of environmental influence.

  1. Active vibration control techniques for flexible space structures

    Science.gov (United States)

    Parlos, Alexander G.; Jayasuriya, Suhada

    1990-01-01

    Two proposed control system design techniques for active vibration control in flexible space structures are detailed. Control issues relevant only to flexible-body dynamics are addressed, whereas no attempt was made to integrate the flexible and rigid-body spacecraft dynamics. Both of the proposed approaches revealed encouraging results; however, further investigation of the interaction of the flexible and rigid-body dynamics is warranted.

  2. Algebraic techniques for diagonalization of a split quaternion matrix in split quaternionic mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Tongsong, E-mail: jiangtongsong@sina.com [Department of Mathematics, Linyi University, Linyi, Shandong 276005 (China); Department of Mathematics, Heze University, Heze, Shandong 274015 (China); Jiang, Ziwu; Zhang, Zhaozhong [Department of Mathematics, Linyi University, Linyi, Shandong 276005 (China)

    2015-08-15

    In the study of the relation between complexified classical and non-Hermitian quantum mechanics, physicists found that there are links to quaternionic and split quaternionic mechanics, and this leads to the possibility of employing algebraic techniques of split quaternions to tackle some problems in complexified classical and quantum mechanics. This paper, by means of real representation of a split quaternion matrix, studies the problem of diagonalization of a split quaternion matrix and gives algebraic techniques for diagonalization of split quaternion matrices in split quaternionic mechanics.

  3. An Approach to Acoustic Emission Technique Applications to Evaluate Damage Mechanisms in Composite Materials

    Directory of Open Access Journals (Sweden)

    Rios-Soberanis C.R.

    2015-01-01

    Full Text Available Acoustic Emission technique is a versatile method for characterization in materials science. It is considered to be a “passive” non-destructive method since damage can be only evaluated when de defects are being developed during the test which, at the end of the day, it is considered an advantage because failure mechanisms and damage process can be monitored and identified during the load history. When a failure mechanism is activated due to a discontinuity in the material such as crack propagation, part of the total strain energy is dissipated as an elastic waves that propagate from the damage source through the medium. Therefore, this released energy can be detected by piezoelectric sensors that perceive the emitted signal from the damage notation site by the surface dynamic movement and convert it in an electrical response. Acoustic emission signals can be correlated with the onset of damage process occurring in the tested materials and also to de diverse failure mechanisms such as matrix cracking, interface damage, fiber fracture, etc. This paper proposes to discuss our information and results on acoustic emission materials characterization undertaken on different types of materials.

  4. Fracture mechanisms in biopolymer films using coupling of mechanical analysis and high speed visualization technique

    NARCIS (Netherlands)

    Paes, S.S.; Yakimets, I.; Wellner, N.; Hill, S.E.; Wilson, R.H.; Mitchell, J.R.

    2010-01-01

    The aim of this study was to provide a detailed description of the fracture mechanisms in three different biopolymer thin materials: gelatin, hydroxypropyl cellulose (HPC) and cassava starch films. That was achieved by using a combination of fracture mechanics methodology and in situ visualization w

  5. Wheelchair propulsion technique and mechanical efficiency after 3 wk of practice

    NARCIS (Netherlands)

    De Groot, Sonja; Veeger, Dirkan H E J; Hollander, A Peter; Van der Woude, Lucas H V

    2002-01-01

    PURPOSE: Differences in gross mechanical efficiency between experienced and inexperienced wheelchair users may be brought about by differences in propulsion technique. The purpose of this experiment was to study changes in propulsion technique (defined by force application, left-right symmetry, inte

  6. Wheelchair propulsion technique and mechanical efficiency after 3 wk of practice

    NARCIS (Netherlands)

    De Groot, Sonja; Veeger, Dirkan H E J; Hollander, A Peter; Van der Woude, Lucas H V

    2002-01-01

    PURPOSE: Differences in gross mechanical efficiency between experienced and inexperienced wheelchair users may be brought about by differences in propulsion technique. The purpose of this experiment was to study changes in propulsion technique (defined by force application, left-right symmetry, inte

  7. Identification of the Scale of Changes in Personnel Motivation Techniques at Mechanical-Engineering Enterprises

    OpenAIRE

    Melnyk Olga G.; Bodaretska Olha M.

    2016-01-01

    The method for identification of the scale of changes in personnel motivation techniques at mechanical-engineering enterprises based on structural and logical sequence of implementation of relevant stages (identification of the mission, strategy and objectives of the enterprise; forecasting the development of the enterprise business environment; SWOT-analysis of actual motivation techniques, deciding on the scale of changes in motivation techniques, choosing providers for ch...

  8. Surface dielectric relaxation: probing technique and its application to thermal activation dynamics of polymer surface.

    Science.gov (United States)

    Ishii, Masashi

    2010-09-01

    For dynamic analyses of a polymer surface, a dielectric relaxation measurement technique with parallel electrodes placed away from the surface was developed. In this technique, a liquid heating medium was filled in the space between the polymer surface and the electrodes. The construction that maintains the surface can clarify the physical interactions between the liquid and the bare surface and controlling the temperature of the liquid reveals the thermal activation property of the surface. The dielectric relaxation spectrum of the surface convoluted into the bulk and liquid spectra can be obtained by a reactance analysis and the surface spectrum is expressed with an equivalent resistance-capacitance parallel circuit. On the basis of the electromechanical analogy, the electric elements can be converted into mechanical elements that indicate the viscoelasticity of the polymer surface. Using these measurement and analysis techniques, the electric and mechanical properties of the surface of a gelatinized chloroprene rubber sample were analyzed.

  9. Rotors on Active Magnetic Bearings: Modeling and Control Techniques

    OpenAIRE

    Tonoli, Andrea; Bonfitto, Angelo; Silvagni, Mario; Suarez, Lester D.

    2012-01-01

    In the last decades the deeper and more detailed understanding of rotating machinery dynamic behavior facilitated the study and the design of several devices aiming at friction reduction, vibration damping and control, rotational speed increase and mechanical design optimization. Among these devices a promising technology is represented by active magnetic actuators which found a great spread in rotordynamics and in high precision applications due to (a) the absence of all fatigue and tribolog...

  10. Flue Gas Desulfurization by Mechanically and Thermally Activated Sodium Bicarbonate

    Directory of Open Access Journals (Sweden)

    Walawska Barbara

    2014-09-01

    Full Text Available This paper presents the results of study on structural parameters (particle size, surface area, pore volume and the sorption ability of mechanically and thermally activated sodium bicarbonate. The sorption ability of the modified sorbent was evaluated by: partial and overall SO2 removal efficiency, conversion rate, normalized stoichiometric ratio (NSR. Sodium bicarbonate was mechanically activated by various grinding techniques, using three types of mills: fluid bed opposed jet mill, fine impact mill and electromagnetic mill, differing in grinding technology. Grounded sorbent was thermally activated, what caused a significant development of surface area. During the studies of SO2 sorption, a model gas with a temperature of 300°C, of composition: sulfur dioxide at a concentration of 6292 mg/mn3, oxygen, carbon dioxide and nitrogen as a carrier gas, was used. The best development of surface area and the highest SO2 removal efficiency was obtained for the sorbent treated by electromagnetic grinding, with simultaneous high conversion rate.

  11. Studies Regarding Design and Optimization of Mechanisms Using Modern Techniques of CAD and CAE

    Directory of Open Access Journals (Sweden)

    Marius Tufoi

    2010-01-01

    Full Text Available The paper presents applications of modern techniques of CAD (Computer Aided Design and CAE (Computer Aided Engineering to design and optimize the mechanisms used in mechanical engineering. The use exemplification of these techniques was achieved by designing and optimizing parts of a drawing installation for horizontal continuous casting of metals. By applying these design methods and using finite element method at simulations on designed mechanisms results a number of advantages over traditional methods of drawing and design: speed in drawing, design and optimization of parts and mechanisms, kinematic analysis option, kinetostatic and dynamic through simulation, without requiring physical realization of the part or mechanism, the determination by finite element method of tension, elongations, travel and safety factor and the possibility of optimization for these sizes to ensure the mechanical strength of each piece separately. Achieving these studies was possible using SolidWorks 2009 software suite.

  12. Surrogate-based modeling and dimension reduction techniques for multi-scale mechanics problems

    Institute of Scientific and Technical Information of China (English)

    Wei Shyy; Young-Chang Cho; Wenbo Du; Amit Gupta; Chien-Chou Tseng; Ann Marie Sastry

    2011-01-01

    Successful modeling and/or design of engineering systems often requires one to address the impact of multiple “design variables” on the prescribed outcome.There are often multiple,competing objectives based on which we assess the outcome of optimization.Since accurate,high fidelity models are typically time consuming and computationally expensive,comprehensive evaluations can be conducted only if an efficient framework is available.Furthermore,informed decisions of the model/hardware's overall performance rely on an adequate understanding of the global,not local,sensitivity of the individual design variables on the objectives.The surrogate-based approach,which involves approximating the objectives as continuous functions of design variables from limited data,offers a rational framework to reduce the number of important input variables,i.e.,the dimension of a design or modeling space.In this paper,we review the fundamental issues that arise in surrogate-based analysis and optimization,highlighting concepts,methods,techniques,as well as modeling implications for mechanics problems.To aid the discussions of the issues involved,we summarize recent efforts in investigating cryogenic cavitating flows,active flow control based on dielectric barrier discharge concepts,and lithium (Li)-ion batteries.It is also stressed that many multi-scale mechanics problems can naturally benefit from the surrogate approach for “scale bridging.”

  13. Cure and mechanical behaviors of cycloaliphatic/DGEBA epoxy blend system using electron-beam technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.R.; Heo, G.Y.; Park, S.J. [Korea Research Institute of Chemical Technology, Taejeon (Korea)

    2002-05-01

    4-Vinyl-1- cyclohexene diepoxide (VCE)/ diglycidyl ether of bisphenol -A(DGEBA) epoxy blends with benzylquinoxalinium hexafluoroanti-monate were cured using an electron-beam technique. the effect of DGEBA content to VCE on cure behavior, thermal stabilities, and mechanical properties was investigated. The composition of VCE/DGEBA blend system varied within 100:0, 80:20, 60:40. 40:60 20:80, and 0:100wt%. The cure behavior and thermal stability of the cured specimens was monited by near-infrared spectroscopy and thermogravimetric analysis, respectively. Also, the critical stress intensity factor (K{sub 1C}) test of the cured specimens was performed to study the mechanical interfacial properties. As a result, the decreases of short side-chide structure and chain scission were observed in NIR measurements as the DGEBA content increases, resulting in varying the hydroxyl and carbonyl groups. And, the initial decomposition temperature (IDT), temperature of maximum weight loss (T{sub max}), and decomposition activation energy (E{sub d}) as thermal stability factors were increased with increasing the DGEBA content. These results could be explained by mean of decreasing viscosity, stable aromatic ring structure, and grafted interpenetrating polymer network with increasing of DGEBA content. Also, the maximum K{sub 1C} value showed at mixing ratio of 40:60 wt% in this blend system. (author). 22 refs., 2 tabs., 6 figs.

  14. Evaluation of Wellness Detection Techniques using Complex Activities Association for Smart Home Ambient

    Directory of Open Access Journals (Sweden)

    Farhan Sabir Ujager

    2016-08-01

    Full Text Available Wireless Sensor Network based smart homes have the potential to meet the growing challenges of independent living of elderly people in smart homes. However, wellness detection of elderly people in smart homes is still a challenging research domain. Many researchers have proposed several techniques; however, majority of these techniques does not provide a comprehensive solution because complex activities cannot be determined easily and comprehensive wellness is difficult to diagnose. In this study’s critical review, it has been observed that strong association lies among the vital wellness determination parameters. In this paper, an association rules based model is proposed for the simple and complex (overlapped activities recognition and comprehensive wellness detection mechanism after analyzing existing techniques. It considers vital wellness detection parameters (temporal association of sub activity location and sub activity, time gaps between two adjacent activities, temporal association of inter and intra activities. Activity recognition and wellness detection will be performed on the basis of extracted temporal association rules and expert knowledgebase. Learning component is an important module of our proposed model to accommodate the changing trends in the frequent pattern behavior of an elderly person and recommend a caregiver/expert to adjust the expert knowledgebase according to the found abnormalities.

  15. Application of Active Flow Control Technique for Gust Load Alleviation

    Institute of Scientific and Technical Information of China (English)

    XU Xiaoping; ZHU Xiaoping; ZHOU Zhou; FAN Ruijun

    2011-01-01

    A new gust load alleviation technique is presented in this paper based on active flow control.Numerical studies are conducted to investigate the beneficial effects on the aerodynamic characteristics of the quasi “Global Hawk” airfoil using arrays of jets during the gust process.Based on unsteady Navier-Stokes equations,the grid-velocity method is introduced to simulate the gust influence,and dynamic response in vertical gust flow perturbation is investigated for the airfoil as well.An unsteady surface transpiration boundary condition is enforced over a user specified portion of the airfoil's surface to emulate the time dependent velocity boundary conditions.Firstly,after applying this method to simulate typical NACA0006 airfoil gust response to a step change in the angle of attack,it shows that the indicial responses of the airfoil make good agreement with the exact theoretical values and the calculated values in references.Furthermore,gust response characteristic for the quasi “Global Hawk” airfoil is analyzed.Five kinds of flow control techniques are introduced as steady blowing,steady suction,unsteady blowing,unsteady suction and synthetic jets.The physical analysis of the influence on the effects of gust load alleviation is proposed to provide some guidelines for practice.Numerical results have indicated that active flow control technique,as a new technology of gust load alleviation,can affect and suppress the fluid disturbances caused by gust so as to achieve the purpose of gust load alleviation.

  16. Development of Numerical Analysis Techniques Based on Damage Mechanics and Fracture Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yoon Suk; Lee, Dock Jin; Choi, Shin Beom; Kim, Sun Hye; Cho, Doo Ho; Lee, Hyun Boo [Sungkyunkwan University, Seoul (Korea, Republic of)

    2010-04-15

    The scatter of measured fracture toughness data and transferability problems among different crack configurations as well as geometry and loading conditions are major obstacles for application of fracture mechanics. To address these issues, recently, concerns on the local approach employing reliable micro-mechanical damage models are being increased again in connection with a progress of computational technology. In the present research, as part of development of fracture mechanical evaluation model for material degradation of reactor pressure boundary, several investigations on fracture behaviors were carried out. Especially, a numerical scheme to determine key parameters consisting both cleavage and ductile fracture estimate models was changed efficiently by incorporating a genetic algorithm. Also, with regard to the well-known master curve, newly reported methods such as bimodal master curve, randomly inhomogeneous master curve and single point estimation were reviewed to deal with homogeneous and inhomogeneous material characteristics. A series of preliminary finite element analyses was conducted to examine the element size effect on micro-mechanical models. Then, a new thickness correction equation was derived from parametric three-dimensional numerical simulations, which was founded on the current test standard, ASTM E1921, but could lead to get more realistic fracture toughness values. As a result, promising modified master curves as well as fracture toughness diagrams to convert data between pre-cracked V-notched and compact tension specimens were generated. Moreover, a user-subroutine in relation to GTN(Gurson-Tvergaard-Needleman) model was made by adopting Hill's 48 yield potential theory. By applying GTN model combined with the subroutine to small punch specimens, the effect of inhomogeneous properties on fracture behaviors of miniature specimens was confirmed. Therefore, it is anticipated that the aforementioned enhanced research results can be

  17. Teaching Computational Geophysics Classes using Active Learning Techniques

    Science.gov (United States)

    Keers, H.; Rondenay, S.; Harlap, Y.; Nordmo, I.

    2016-12-01

    We give an overview of our experience in teaching two computational geophysics classes at the undergraduate level. In particular we describe The first class is for most students the first programming class and assumes that the students have had an introductory course in geophysics. In this class the students are introduced to basic Matlab skills: use of variables, basic array and matrix definition and manipulation, basic statistics, 1D integration, plotting of lines and surfaces, making of .m files and basic debugging techniques. All of these concepts are applied to elementary but important concepts in earthquake and exploration geophysics (including epicentre location, computation of travel time curves for simple layered media plotting of 1D and 2D velocity models etc.). It is important to integrate the geophysics with the programming concepts: we found that this enhances students' understanding. Moreover, as this is a 3 year Bachelor program, and this class is taught in the 2nd semester, there is little time for a class that focusses on only programming. In the second class, which is optional and can be taken in the 4th or 6th semester, but often is also taken by Master students we extend the Matlab programming to include signal processing and ordinary and partial differential equations, again with emphasis on geophysics (such as ray tracing and solving the acoustic wave equation). This class also contains a project in which the students have to write a brief paper on a topic in computational geophysics, preferably with programming examples. When teaching these classes it was found that active learning techniques, in which the students actively participate in the class, either individually, in pairs or in groups, are indispensable. We give a brief overview of the various activities that we have developed when teaching theses classes.

  18. 7th International Symposium on Applications of Laser Techniques to Fluid Mechanics, volume 2

    Science.gov (United States)

    1994-07-01

    The proceedings volumes 1 and 2 comprise the papers that were accepted for presentation at the Seventh International Symposium on Applications of Laser Techniques to Fluid Mechanics held at The Calouste Gulbenkian Foundation in Lisbon, during the period of July 11 to 14, 1994. The prime objective of this Seventh Symposium is to provide a forum for the presentation of the most advanced research on laser techniques for flow measurements, and reveal significant results to fluid mechanics. The applications of laser techniques to scientific and engineering fluid flow research is emphasized, but contributions to the theory and practice of laser methods are also considered where they facilitate new improved fluid mechanic research. Attention is focused on laser-Doppler anemometry, particle sizing and other methods for the measurement of velocity and scalars such as particle image velocimetry and laser induced fluorescence.

  19. 7th International Symposium on Applications of Laser Techniques to Fluid Mechanics, volume 1

    Science.gov (United States)

    1994-07-01

    The proceedings volumes 1 and 2 comprise the papers that were accepted for presentation at the Seventh International Symposium on Applications of Laser Techniques to Fluid Mechanics held at The Calouste Gulbenkian Foundation in Lisbon, during the period of July 11 to 14, 1994. The prime objective of this Seventh Symposium is to provide a forum for the presentation of the most advanced research on laser techniques for flow measurements, and reveal significant results to fluid mechanics. The applications of laser techniques to scientific and engineering fluid flow research is emphasized, but contributions to the theory and practice of laser methods are also considered where they facilitate new improved fluid mechanics research. Attention is focused on laser-Doppler anemometry, particle sizing and other methods for the measurement of velocity and scalars such as particle image velocimetry and laser induced fluorescence.

  20. THE RESEARCH TECHNIQUES FOR ANALYSIS OF MECHANICAL AND TRIBOLOGICAL PROPERTIES OF COATING-SUBSTRATE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Kinga CHRONOWSKA-PRZYWARA

    2014-06-01

    Full Text Available The article presents research techniques for the analysis of both mechanical and tribological properties of thin coatings applied on highly loaded machine elements. In the Institute of Machine Design and Exploitation, AGH University of Science and Technology students of the second level of Mechanical Engineering study tribology attending laboratory class. Students learn on techniques for mechanical and tribological testing of thin, hard coatings deposited by PVD and CVD technologies. The program of laboratories contains micro-, nanohardness and Young's modulus measurements by instrumental indentations and analysys of coating to substrate adhesion by scratch testing. The tribological properties of the coating-substrate systems are studied using various techniques, mainly in point contact load conditions with ball-on-disc and block-on-ring tribomiters as well as using ball cratering method in strongly abrasive suspensions.

  1. Progress in phototaxis mechanism research and micromanipulation techniques of algae cells

    Institute of Scientific and Technical Information of China (English)

    WEN Chenglu; LI Heng; WANG Pengbo; LI Wei; ZHAO Jingquan

    2007-01-01

    Phototactic movement is a characteristic of some microorganisms' response to light environment. Most of the algae have dramatically phototactic responses, underlying the complicated biological, physical and photochemical mechanisms are involved. With the development of the micro/nano and sensor techniques, great progress has been made in the research of the algae phototaxis. This review article summarizes the progress made in the research on the functional phototactic structures, the mechanisms of photo-response process and photodynamics of phototaxis in algae, and describes the latest developed micro-tracking technique and micromanipulation technique.Moreover, based on our own research results, the potential correlation between the phototaxis and photosynthesis is discussed, and the directions for future research of the phototactic mechanism are proposed.

  2. Patch Clamp: A Powerful Technique for Studying the Mechanism of Acupuncture

    Directory of Open Access Journals (Sweden)

    D. Zhang

    2012-01-01

    Full Text Available Cellular and molecular events can be investigated using electrophysiological techniques. In particular, the patch-clamp method provides detailed information. In addition, the patch-clamp technique has become a powerful method for investigating the mechanisms underlying the effects of acupuncture. In this paper, recent researches on how acupuncture might modulate electrophysiological responses in the central nervous system (CNS and affect peripheral structures are reviewed.

  3. Smart actuators: a novel technique for active damping

    Science.gov (United States)

    Muth, Michael; Moldovan, Klaus; Goetz, Bernt

    1995-05-01

    Sensors are important components for any automatic process. Their function is to measure physical variables, and thus to allow automatic actions in a technical process, for example in a manufacturing sequence or a measurement. Selecting a sensor for a process, it is mostly overlooked that actuators used in a process also have sensory properties. The reactions of actuators to the state of a process give the possibility to extract relevant information out of the process with actuators. In using the sensory properties of actuators the costs for additional sensors can be saved. Even more important, under some circumstances it may not even be possible to place a special sensor directly at the location of interest: In that case the information about the physical variable is only accessible by analyzing the return signal of the actuator. An example of such a smart actuator combining active and sensory properties is demonstrated in a simple experiment. This experiment shows a steel ball supported as a pendulum. The steel ball can be pushed off, and on swinging back it can be caught in a single pass without any bounce. The actuator uses the piezoelectric effect which shows the underlying principle most clearly: Application of the reversibility of physical effects. In this case mechanical energy can either be produced or absorbed. This experiment is means as a demonstration model for students. It is also used for preliminary investigations developing a fast, actively damped tipping mechanism (optical scanner).

  4. Effect of quenching techniques on the mechanical properties of low carbon structural steel

    Directory of Open Access Journals (Sweden)

    K. Miernik

    2010-07-01

    Full Text Available The paper presents the results of the impact of incomplete quenching technique on the mechanical properties of low carbon structural steel.Significant influence of the heating method to the α + γ field was observed on the strength and plasticity after hardening process. The best combination of mechanical properties was obtained for the 3th technique consisting of pre-heating the material to the austenite field, next cooling to the appropriate temperature in the α + γ and hardening from that dual phase region. The high level of toughness with relatively high strength were observed, compared to the properties obtained for the two other ways to quench annealing (incomplete hardening.

  5. Active Learning Techniques Applied to an Interdisciplinary Mineral Resources Course.

    Science.gov (United States)

    Aird, H. M.

    2015-12-01

    An interdisciplinary active learning course was introduced at the University of Puget Sound entitled 'Mineral Resources and the Environment'. Various formative assessment and active learning techniques that have been effective in other courses were adapted and implemented to improve student learning, increase retention and broaden knowledge and understanding of course material. This was an elective course targeted towards upper-level undergraduate geology and environmental majors. The course provided an introduction to the mineral resources industry, discussing geological, environmental, societal and economic aspects, legislation and the processes involved in exploration, extraction, processing, reclamation/remediation and recycling of products. Lectures and associated weekly labs were linked in subject matter; relevant readings from the recent scientific literature were assigned and discussed in the second lecture of the week. Peer-based learning was facilitated through weekly reading assignments with peer-led discussions and through group research projects, in addition to in-class exercises such as debates. Writing and research skills were developed through student groups designing, carrying out and reporting on their own semester-long research projects around the lasting effects of the historical Ruston Smelter on the biology and water systems of Tacoma. The writing of their mini grant proposals and final project reports was carried out in stages to allow for feedback before the deadline. Speakers from industry were invited to share their specialist knowledge as guest lecturers, and students were encouraged to interact with them, with a view to employment opportunities. Formative assessment techniques included jigsaw exercises, gallery walks, placemat surveys, think pair share and take-home point summaries. Summative assessment included discussion leadership, exams, homeworks, group projects, in-class exercises, field trips, and pre-discussion reading exercises

  6. Mechanically Flexible Active Silicon Chips and Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Using innovative chip thinning technology married with recently available packaging technology, this effort will produce Mechanically Flexible Multifunctional Active...

  7. Intracellular mechanisms of lymphoid cell activation.

    Science.gov (United States)

    Fresa, K; Hameed, M; Cohen, S

    1989-01-01

    Activation of lymphocytes for proliferation is associated with the appearance of an intracellular factor (ADR) that can induce DNA synthesis in isolated quiescent nuclei. ADR plays a role in the sequence of intracellular events leading to activation for IL-2-mediated proliferation. Because of the nature of the defining assay, the locus of ADR action appears to be near the terminal end of the transduction pathway. Interestingly, although lymphocytes from aged individuals respond poorly to proliferative stimuli, they appear to produce normal to above-normal levels of ADR. In contrast, their nuclei are only poorly responsive to stimulation by ADR. Preparations rich in ADR activity have proteolytic activity as well. In addition, aprotinin, as well as a variety of other protease inhibitors, suppresses ADR-induced DNA synthesis in a dose-dependent manner. ADR activity can be removed from active extracts by absorption with aprotinin-conjugated agarose beads, and can be removed from the beads by elution at pH 5.0. This latter suggests that ADR itself is a protease. However, its endogenous substrate is not yet known. We have also detected an inhibitor of ADR activity in the cytoplasm of resting lymphocytes. This is a heat-stable protein of approximately 60,000 Da. In addition to suppressing the interaction of ADR with quiescent nuclei, the inhibitor can suppress DNA synthetic activity of replicative nuclei isolated from mitogen-activated lymphocytes. Interestingly, these preparations had little or no activity on replicative nuclei derived from several neoplastic cell lines. The resistance of tumor cell nuclei to spontaneously occurring cytoplasmic inhibitory factors such as the one described here may provide one explanation for the loss of growth control in neoplastic cells.

  8. Nondestructive techniques for characterizing mechanical properties of structural materials - An overview

    Science.gov (United States)

    Vary, A.; Klima, S. J.

    1986-01-01

    An overview of nondestructive evaluation (NDE) is presented to indicate the availability and application potentials of techniques for quantitative characterization of the mechanical properties of structural materials. The purpose is to review NDE techniques that go beyond the usual emphasis on flow detection and characterization. Discussed are current and emerging NDE techniques that can verify and monitor entrinsic properties (e.g., tensile, shear, and yield strengths; fracture toughness, hardness, ductility; elastic moduli) and underlying microstructural and morphological factors. Most of the techniques described are, at present, neither widely applied nor widely accepted in commerce and industry because they are still emerging from the laboratory. The limitations of the techniques may be overcome by advances in applications research and instrumentation technology and perhaps by accommodations for their use in the design of structural parts.

  9. Nondestructive techniques for characterizing mechanical properties of structural materials: An overview

    Science.gov (United States)

    Vary, A.; Klima, S. J.

    1985-01-01

    An overview of nondestructive evaluation (NDE) is presented to indicate the availability and application potentials of techniques for quantitative characterization of the mechanical properties of structural materials. The purpose is to review NDE techniques that go beyond the usual emphasis on flaw detection and characterization. Discussed are current and emerging NDE techniques that can verify and monitor entrinsic properties (e.g., tensile, shear, and yield strengths; fracture toughness, hardness, ductility; elastic moduli) and underlying microstructural and morphological factors. Most of the techniques described are, at present, neither widely applied nor widely accepted in commerce and industry because they are still emerging from the laboratory. The limitations of the techniques may be overcome by advances in applications research and instrumentation technology and perhaps by accommodations for their use in the design of structural parts.

  10. Insights into Mechanism of Glucokinase Activation

    Science.gov (United States)

    Liu, Shenping; Ammirati, Mark J.; Song, Xi; Knafels, John D.; Zhang, Jeff; Greasley, Samantha E.; Pfefferkorn, Jeffrey A.; Qiu, Xiayang

    2012-01-01

    Human glucokinase (GK) is a principal regulating sensor of plasma glucose levels. Mutations that inactivate GK are linked to diabetes, and mutations that activate it are associated with hypoglycemia. Unique kinetic properties equip GK for its regulatory role: although it has weak basal affinity for glucose, positive cooperativity in its binding of glucose causes a rapid increase in catalytic activity when plasma glucose concentrations rise above euglycemic levels. In clinical trials, small molecule GK activators (GKAs) have been efficacious in lowering plasma glucose and enhancing glucose-stimulated insulin secretion, but they carry a risk of overly activating GK and causing hypoglycemia. The theoretical models proposed to date attribute the positive cooperativity of GK to the existence of distinct protein conformations that interconvert slowly and exhibit different affinities for glucose. Here we report the respective crystal structures of the catalytic complex of GK and of a GK-glucose complex in a wide open conformation. To assess conformations of GK in solution, we also carried out small angle x-ray scattering experiments. The results showed that glucose dose-dependently converts GK from an apo conformation to an active open conformation. Compared with wild type GK, activating mutants required notably lower concentrations of glucose to be converted to the active open conformation. GKAs decreased the level of glucose required for GK activation, and different compounds demonstrated distinct activation profiles. These results lead us to propose a modified mnemonic model to explain cooperativity in GK. Our findings may offer new approaches for designing GKAs with reduced hypoglycemic risk. PMID:22298776

  11. Performance Analysis for Dispensing Mechanism of Active Code

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The dispensing mechanism of active code is a key technology in an active network. Conventional capsule and programmable switch approaches have their own shortcomings. The DCCAN(distributed code caching for active network) mechanism presented in this paper overcomes these shortcomings. In this paper, capsule and programmable switch approaches are introduced, and their shortcomings are analyzed. The principle of the DCCAN mechanism is described. The theory analysis in transmit width based on the DCCAN mechanism and capsule approach are described. The theory analysis shows that the DCCAN mechanism has many good characteristics and can improve the efficiency of an active network. Key factors which affect the transmit width based on the DCCAN mechanism are discussed. The using condition of the DCCAN mechanism is also discussed.

  12. Identification of the Scale of Changes in Personnel Motivation Techniques at Mechanical-Engineering Enterprises

    Directory of Open Access Journals (Sweden)

    Melnyk Olga G.

    2016-02-01

    Full Text Available The method for identification of the scale of changes in personnel motivation techniques at mechanical-engineering enterprises based on structural and logical sequence of implementation of relevant stages (identification of the mission, strategy and objectives of the enterprise; forecasting the development of the enterprise business environment; SWOT-analysis of actual motivation techniques, deciding on the scale of changes in motivation techniques, choosing providers for changing personnel motivation techniques, choosing an alternative to changing motivation techniques, implementation of changes in motivation techniques; control over changes in motivation techniques. It has been substantiated that the improved method enables providing a systematic and analytical justification for management decisionmaking in this field and choosing the best for the mechanical-engineering enterprise scale and variant of changes in motivation techniques. The method for identification of the scale of changes in motivation techniques at mechanical-engineering enterprises takes into account the previous, current and prospective character. Firstly, the approach is based on considering the past state in the motivational sphere of the mechanical-engineering enterprise; secondly, the method involves identifying the current state of personnel motivation techniques; thirdly, within the method framework the prospective, which is manifested in strategic vision of the enterprise development as well as in forecasting the development of its business environment, is taken into account. The advantage of the proposed method is that the level of its specification may vary depending on the set goals, resource constraints and necessity. Among other things, this method allows integrating various formalized and non-formalized causal relationships in the sphere of personnel motivation at machine-building enterprises and management of relevant processes. This creates preconditions for a

  13. Underlying mechanisms of improving physical activity behavior after rehabilitation

    NARCIS (Netherlands)

    van der Ploeg, Hidde P; Streppel, Kitty R M; van der Beek, Allard J; van der Woude, Luc H V; van Harten, Wim H; van Mechelen, Willem; van der Woude, Lucas

    2008-01-01

    BACKGROUND: Regular physical activity is beneficial for the health and functioning of people with a disability. Effective components of successful physical activity promotion interventions should be identified and disseminated. PURPOSE: To study the underlying mechanisms of the combined sport stimul

  14. Underlying mechanisms of improving physical activity behavior after rehabilitation

    NARCIS (Netherlands)

    Ploeg, van der Hidde P.; Streppel, Kitty R.M.; Beek, van der Allard J.; Woude, Luc H.V.; Harten, van Wim H.; Mechelen, van Willem

    2008-01-01

    Background: Regular physical activity is beneficial for the health and functioning of people with a disability. Effective components of successful physical activity promotion interventions should be identified and disseminated. Purpose: To study the underlying mechanisms of the combined sport stimul

  15. Arsenic Sorption on Mechanically Activated Magnetite and Olivine

    Directory of Open Access Journals (Sweden)

    Zdenka Bujňáková

    2012-12-01

    Full Text Available Arsenic sorption on mechanically activated minerals such as magnetite Fe3O4 (Kiruna, Sweden and olivine (Mg,Fe2SiO4 (Ǻheim,Norway has been studied and compared in this work. Experiments were carried out with non-activated and mechanically activatedsamples. The activation of both minerals was performed in a planetary mill at different milling conditions. The specific surface areaand consequent sorption activity were enhanced by mechanical activation. The using of olivine seems to be better than magnetite fromthe point of view of milling time, which is necessary for achievement of the same sorption effect.

  16. Mechanics of nonplanar membranes with force-dipole activity

    DEFF Research Database (Denmark)

    Lomholt, Michael Andersen

    2006-01-01

    A study is made of how active membrane proteins can modify the long wavelength mechanics of fluid membranes. The activity of the proteins is modelled as disturbing the protein surroundings through nonlocal force distributions of which a force-dipole distribution is the simplest example. An analyt...... contributions to mechanical properties such as tension and bending moments become apparent. It is also explained how the activity can induce a hydrodynamic attraction between the active proteins in the membrane....

  17. Optimal Control of Active Recoil Mechanisms

    Science.gov (United States)

    1977-02-01

    pressures in different chambers, rod pull are available and can be plotted. A linear state feedback control system is proposed to adapt this...desirable. A linear state feedback control system with variable gains is proposed in the report. A separate control law is designed for each...optimization algorithm to choose a feasible solution. 27 3.3 Results for M-37 Recoil Mechanism The linear state feedback control system and

  18. Quantum Mechanics Version of Wavelet Transform Studied by Virtue of IWOP Technique

    Institute of Scientific and Technical Information of China (English)

    FAN Hong-Yi; L(U) Jian-Feng

    2004-01-01

    Using the technique of integral within an ordered product (IWOP) of operators we show that the wavelet transform can be recasted to a matrix element of squeezing-displacing operator between the mother wavelet state vector and the state vector to be transformed in the context of quantum mechanics. In this way many quantum optical states'wavelet transform can be easily derived.

  19. 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics

    CERN Document Server

    Adrian, R J; Heitor, M V; Maeda, M; Tropea, C; Whitelaw, J H

    2002-01-01

    This volume includes revised and extended versions of selected papers presented at the Tenth International Symposium on Applications of Laser Techniques to Fluid Mechanics held at the Calouste Gulbenkian Foundation in Lisbon, during the period of July 10 to 13, 2000. The papers describe instrumentation developments for Velocity, Scalar and Multi-Phase Flows and results of measurements of Turbulent Flows, and Combustion and Engines. The papers demonstrate the continuing and healthy interest in the development of understanding of new methodologies and implementation in terms of new instrumentation. The prime objective of the Tenth Symposium was to provide a forum for the presentation of the most advanced research on laser techniques for flow measurements, and communicate significant results to fluid mechanics. The application of laser techniques to scientific and engineering fluid flow research was emphasized, but contributions to the theory and practice of laser methods were also considered where they facilita...

  20. Assessment of strain measurement techniques to characterise mechanical properties of structural steel

    Directory of Open Access Journals (Sweden)

    H.B. Motra

    2014-12-01

    Full Text Available Strain measurement is important in mechanical testing. A wide variety of techniques exists for measuring strain in the tensile test; namely the strain gauge, extensometer, stress and strain determined by machine crosshead motion, Geometric Moire technique, optical strain measurement techniques and others. Each technique has its own advantages and disadvantages. The purpose of this study is to quantitatively compare the strain measurement techniques. To carry out the tensile test experiments for S 235, sixty samples were cut from the web of the I-profile in longitudinal and transverse directions in four different dimensions. The geometry of samples are analysed by 3D scanner and vernier caliper. In addition, the strain values were determined by using strain gauge, extensometer and machine crosshead motion. Three techniques of strain measurement are compared in quantitative manner based on the calculation of mechanical properties (modulus of elasticity, yield strength, tensile strength, percentage elongation at maximum force of structural steel. A statistical information was used for evaluating the results. It is seen that the extensometer and strain gauge provided reliable data, however the extensometer offers several advantages over the strain gauge and crosshead motion for testing structural steel in tension. Furthermore, estimation of measurement uncertainty is presented for the basic material parameters extracted through strain measurement.

  1. The novel mechanism of lenalidomide activity.

    Science.gov (United States)

    Fink, Emma C; Ebert, Benjamin L

    2015-11-19

    Lenalidomide acts by a novel drug mechanism-modulation of the substrate specificity of the CRL4(CRBN) E3 ubiquitin ligase. In multiple myeloma, lenalidomide induces the ubiquitination of IKZF1 and IKZF3 by CRL4(CRBN). Subsequent proteasomal degradation of these transcription factors kills multiple myeloma cells. In del(5q) myelodysplastic syndrome, lenalidomide induces the degradation of CK1α, which preferentially affects del(5q) cells because they express this gene at haploinsufficient levels. In the future, modulation of ubiquitin ligase function may enable us to target previously "undruggable" proteins.

  2. Mechanism of Ras Activation by TGFBeta

    Science.gov (United States)

    2002-07-01

    transcriptional activity of the vitamin D receptor (Yanagi- sawa et al, 1999). Smad3 and Smad4 can also associate with the acute myeloid leukemia family of... Ishii , S. (1999). ATF-2 is a common nuclear target of Smad and TAK1 pathways in transforming growth factor-ß signaling. J Biol Chem 274, 8949

  3. Two Major Medicinal Honeys Have Different Mechanisms of Bactericidal Activity

    NARCIS (Netherlands)

    Kwakman, P.H.S.; te Velde, A.A.; de Boer, L.; Vandenbroucke-Grauls, C.M.J.E.; Zaat, S.A.J.

    2011-01-01

    Honey is increasingly valued for its antibacterial activity, but knowledge regarding the mechanism of action is still incomplete. We assessed the bactericidal activity and mechanism of action of Revamil (R) source (RS) honey and manuka honey, the sources of two major medical-grade honeys. RS honey k

  4. [Methodology and Implementation of Forced Oscillation Technique for Respiratory Mechanics Measurement].

    Science.gov (United States)

    Zhang, Zhengbo; Ni, Lu; Liu, Xiaoli; Li, Deyu; Wang, Weidong

    2015-11-01

    The forced oscillation technique (FOT) is a noninvasive method for respiratory mechanics measurement. For the FOT, external signals (e.g. forced oscillations around 4-40 Hz) are used to drive the respiratory system, and the mechanical characteristic of the respiratory system can be determined with the linear system identification theory. Thus, respiratory mechanical properties and components at different frequency and location of the airway can be explored by specifically developed forcing waveforms. In this paper, the theory, methodology and clinical application of the FOT is reviewed, including measure ment theory, driving signals, models of respiratory system, algorithm for impedance identification, and requirement on apparatus. Finally, the future development of this technique is also discussed.

  5. Diffusion of point defects in crystalline silicon using the kinetic activation-relaxation technique method

    Science.gov (United States)

    Trochet, Mickaël; Béland, Laurent Karim; Joly, Jean-François; Brommer, Peter; Mousseau, Normand

    2015-06-01

    We study point-defect diffusion in crystalline silicon using the kinetic activation-relaxation technique (k-ART), an off-lattice kinetic Monte Carlo method with on-the-fly catalog building capabilities based on the activation-relaxation technique (ART nouveau), coupled to the standard Stillinger-Weber potential. We focus more particularly on the evolution of crystalline cells with one to four vacancies and one to four interstitials in order to provide a detailed picture of both the atomistic diffusion mechanisms and overall kinetics. We show formation energies, activation barriers for the ground state of all eight systems, and migration barriers for those systems that diffuse. Additionally, we characterize diffusion paths and special configurations such as dumbbell complex, di-interstitial (IV-pair+2I) superdiffuser, tetrahedral vacancy complex, and more. This study points to an unsuspected dynamical richness even for this apparently simple system that can only be uncovered by exhaustive and systematic approaches such as the kinetic activation-relaxation technique.

  6. FACTORS AFFECTING THE MECHANICAL PROPERTIES OF COMPACT BONE AND MINIATURE SPECIMEN TEST TECHNIQUES: A REVIEW

    Directory of Open Access Journals (Sweden)

    Vandana Chittibabu

    2016-12-01

    Full Text Available This paper presents the review concerning mechanical properties of bone and the miniature specimen test techniques. For developing a realistic understanding of how factors such as moisture content, mineralization, age, species, location, gender, rate of deformation etc. affect the mechanical properties of bone, it is critical to understand the role of these factors. A general survey on existing research work is presented on this aspect. The essential features of miniature specimen test techniques are described, along with the application of small punch test method to evaluate the mechanical behavior of materials. The procedure for the determination of tensile and fracture properties, such as: yield strength, ultimate strength, ductility, fracture toughness etc. using small punch test technique have been described. The empirical equations proposed by various investigators for the prediction of tensile and fracture properties are presented and discussed. In some cases, the predictions of material properties have been essentially made through the finite element simulation. The finite element simulation of miniature specimen test technique is also covered in this review. The use of inverse finite element procedure for the prediction of uniaxial tensile constitutive behaviour of materials is also presented

  7. Mechanism for Clastogenic Activity of Naphthalene

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, Bruce A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-29

    Naphthalene incubations form DNA adducts in vitro in a dose dependent manner in both mouse and rat tissues. Rodent tissue incubations with naphthalene indicate that naphthalene forms as many DNA adducts as Benzo(a)pyrene, a known DNA binding carcinogen. The mouse airway has the greatest number of DNA adducts, corresponding to the higher metabolic activation of naphthalene in this location. Both rat tissues, the rat olfactory (tumor target) and the airways (non-tumor target), have similar levels of NA-DNA adducts, indicating that short term measures of initial adduct formation do not directly correlate with sites of tumor formation in the NTP bioassays.

  8. Mechanism for Clastogenic Activity of Naphthalene

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, Bruce A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-06-24

    Naphthalene incubations form DNA adducts in vitro in a dose dependent manner in both mouse and rat tissues. Rodent tissue incubations with naphthalene indicate that naphthalene forms as many DNA adducts as Benzo(a)pyrene, a known DNA binding carcinogen. The mouse airway has the greatest number of DNA adducts, corresponding to the higher metabolic activation of naphthalene in this location. Both rat tissues, the rat olfactory (tumor target) and the airways (non-tumor target), have similar levels of NA-DNA adducts, indicating that short term measures of initial adduct formation do not directly correlate with sites of tumor formation in the NTP bioassays.

  9. Strain Rate Dependency of Bronze Metal Matrix Composite Mechanical Properties as a Function of Casting Technique

    Science.gov (United States)

    Brown, Lloyd; Joyce, Peter; Radice, Joshua; Gregorian, Dro; Gobble, Michael

    2012-07-01

    Strain rate dependency of mechanical properties of tungsten carbide (WC)-filled bronze castings fabricated by centrifugal and sedimentation-casting techniques are examined, in this study. Both casting techniques are an attempt to produce a functionally graded material with high wear resistance at a chosen surface. Potential applications of such materials include shaft bushings, electrical contact surfaces, and brake rotors. Knowledge of strain rate-dependent mechanical properties is recommended for predicting component response due to dynamic loading or impact events. A brief overview of the casting techniques for the materials considered in this study is followed by an explanation of the test matrix and testing techniques. Hardness testing, density measurement, and determination of the volume fraction of WC particles are performed throughout the castings using both image analysis and optical microscopy. The effects of particle filling on mechanical properties are first evaluated through a microhardness survey of the castings. The volume fraction of WC particles is validated using a thorough density survey and a rule-of-mixtures model. Split Hopkinson Pressure Bar (SHPB) testing of various volume fraction specimens is conducted to determine strain dependence of mechanical properties and to compare the process-property relationships between the two casting techniques. The baseline performances of C95400 bronze are provided for comparison. The results show that the addition of WC particles improves microhardness significantly for the centrifugally cast specimens, and, to a lesser extent, in the sedimentation-cast specimens, largely because the WC particles are more concentrated as a result of the centrifugal-casting process. Both metal matrix composites (MMCs) demonstrate strain rate dependency, with sedimentation casting having a greater, but variable, effects on material response. This difference is attributed to legacy effects from the casting process, namely

  10. FTIR Analysis of Alkali Activated Slag and Fly Ash Using Deconvolution Techniques

    Science.gov (United States)

    Madavarapu, Sateesh Babu

    The studies on aluminosilicate materials to replace traditional construction materials such as ordinary Portland cement (OPC) to reduce the effects caused has been an important research area for the past decades. Many properties like strength have already been studied and the primary focus is to learn about the reaction mechanism and the effect of the parameters on the formed products. The aim of this research was to explore the structural changes and reaction product analysis of geopolymers (Slag & Fly Ash) using Fourier transform infrared spectroscopy (FTIR) and deconvolution techniques. Spectroscopic techniques give valuable information at a molecular level but not all methods are economic and simple. To understand the mechanisms of alkali activated aluminosilicate materials, attenuated total reflectance (ATR) FTIR has been used where the effect of the parameters on the reaction products have been analyzed. To analyze complex systems like geopolymers using FTIR, deconvolution techniques help to obtain the properties of a particular peak attributed to a certain molecular vibration. Time and temperature dependent analysis were done on slag pastes to understand the polymerization of reactive silica in the system with time and temperature variance. For time dependent analysis slag has been activated with sodium and potassium silicates using two different `n'values and three different silica modulus [Ms- (SiO2 /M2 O)] values. The temperature dependent analysis was done by curing the samples at 60°C and 80°C. Similarly fly ash has been studied by activating with alkali hydroxides and alkali silicates. Under the same curing conditions the fly ash samples were evaluated to analyze the effects of added silicates for alkali activation. The peak shifts in the FTIR explains the changes in the structural nature of the matrix and can be identified using the deconvolution technique. A strong correlation is found between the concentrations of silicate monomer in the

  11. Activity report of Mechanical Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    1997-07-01

    On April 1997, National Laboratory for High Energy Physics (KEK), Institute of Nuclear Study, University of Tokyo (INS), and Meson Science Laboratory; Faculty of Science, University of Tokyo began to work newly as High Energy Accelerator Research Organization after reconstructing and converting their systems, under aiming at further development of a wide field of accelerator science using a high energy accelerator. Hitherto, the large scale research plans of accelerator at the KEK have been not only received their relation communities on learning importance, meanings and social factors from their stages, but also promoted carefully under opinions and evaluation of outer objective ones and received outer serious evaluations for established research results either. Mechanical Engineering Center belonging to Applied Research Laboratory in the new Organization, started under jointing some sections relating to KEK and INS. As separately operating at the old organization engineering center in Tsukuba area and at engineering room in Tanashi Laboratory for some years, the Center was intended to integrate after 2000 to use this evaluation results for future development. This report was prepared separately on actions at the old engineering center of KEK as its first section and the engineering room of INS as its second section. (G.K.)

  12. Plasma membrane mechanical stress activates TRPC5 channels.

    Directory of Open Access Journals (Sweden)

    Bing Shen

    Full Text Available Mechanical forces exerted on cells impose stress on the plasma membrane. Cells sense this stress and elicit a mechanoelectric transduction cascade that initiates compensatory mechanisms. Mechanosensitive ion channels in the plasma membrane are responsible for transducing the mechanical signals to electrical signals. However, the mechanisms underlying channel activation in response to mechanical stress remain incompletely understood. Transient Receptor Potential (TRP channels serve essential functions in several sensory modalities. These channels can also participate in mechanotransduction by either being autonomously sensitive to mechanical perturbation or by coupling to other mechanosensory components of the cell. Here, we investigated the response of a TRP family member, TRPC5, to mechanical stress. Hypoosmolarity triggers Ca2+ influx and cationic conductance through TRPC5. Importantly, for the first time we were able to record the stretch-activated TRPC5 current at single-channel level. The activation threshold for TRPC5 was found to be 240 mOsm for hypoosmotic stress and between -20 and -40 mmHg for pressure applied to membrane patch. In addition, we found that disruption of actin filaments suppresses TRPC5 response to hypoosmotic stress and patch pipette pressure, but does not prevent the activation of TRPC5 by stretch-independent mechanisms, indicating that actin cytoskeleton is an essential transduction component that confers mechanosensitivity to TRPC5. In summary, our findings establish that TRPC5 can be activated at the single-channel level when mechanical stress on the cell reaches a certain threshold.

  13. Compensatory mechanisms activated with intermittent energy restriction

    DEFF Research Database (Denmark)

    Coutinho, Sílvia Ribeiro; Halset, Eline Holli; Gåsbakk, Sigrid

    2017-01-01

    : 39 ± 9 y) with obesity (BMI: 36 ± 4 kg/m2) were randomized to lose a similar weight with an IER (N = 18) or a CER (N = 17) diet over a 12 week period. Macronutrient composition and overall energy restriction (33% reduction) were similar between groups. Body weight/composition, RMR, fasting......) were measured before and after WL. Results: Changes in body weight (≈12.5% WL) and composition were similar in both groups. Fasting RQ and ExEff at 10 W increased in both groups. Losing weight, either by IER or CER dieting, did not induce significant changes in subjective appetite ratings. RMR......Background & aims: Strong compensatory responses, with reduced resting metabolic rate (RMR), increased exercise efficiency (ExEff) and appetite, are activated when weight loss (WL) is achieved with continuous energy restriction (CER), which try to restore energy balance. Intermittent energy...

  14. The Adsorption Mechanism of Modified Activated Carbon on Phenol

    OpenAIRE

    Lin J. Q.; Yang S. E.; Duan J. M.; Wu J.J.; Jin L. Y.; Lin J. M.; Deng Q. L.

    2016-01-01

    Modified activated carbon was prepared by thermal treatment at high temperature under nitrogen flow. The surface properties of the activated carbon were characterized by Boehm titration, BET and point of zero charge determination. The adsorption mechanism of phenol on modified activated carbon was explained and the adsorption capacity of modified activated carbon for phenol when compared to plain activated carbon was evaluated through the analysis of adsorption isotherms, thermodynamic and ki...

  15. Experimental Techniques for the Measurement of Mechanical Properties of Materials Used in Microelectromechanical Systems

    Directory of Open Access Journals (Sweden)

    Samir V. Kamat

    2009-11-01

    Full Text Available The knowledge of mechanical properties of materials used in microelectromechanical systems (MEMS devices is critical not only in designing structures such as cantilevers and beams but also for ensuring their reliability during operation of these devices. It has been established that the mechanical properties are scaleand-process-dependent, and hence it is essential to measure the mechanical properties of these materials at the same length scale and using the same process as that used in their usage in MEMS devices. The various experimental techniques in vogue to measure the mechanical properties of these materials are briefly reviewed. The facilities established at the Defence Metallurgical Research Laboratory, Hyderabad, and their capabilities are also highlighted.Defence Science Journal, 2009, 59(6, pp.605-615, DOI:http://dx.doi.org/10.14429/dsj.59.1565

  16. Innovative techniques to analyze time series of geomagnetic activity indices

    Science.gov (United States)

    Balasis, Georgios; Papadimitriou, Constantinos; Daglis, Ioannis A.; Potirakis, Stelios M.; Eftaxias, Konstantinos

    2016-04-01

    Magnetic storms are undoubtedly among the most important phenomena in space physics and also a central subject of space weather. The non-extensive Tsallis entropy has been recently introduced, as an effective complexity measure for the analysis of the geomagnetic activity Dst index. The Tsallis entropy sensitively shows the complexity dissimilarity among different "physiological" (normal) and "pathological" states (intense magnetic storms). More precisely, the Tsallis entropy implies the emergence of two distinct patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a higher degree of organization, and (ii) a pattern associated with normal periods, which is characterized by a lower degree of organization. Other entropy measures such as Block Entropy, T-Complexity, Approximate Entropy, Sample Entropy and Fuzzy Entropy verify the above mentioned result. Importantly, the wavelet spectral analysis in terms of Hurst exponent, H, also shows the existence of two different patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a fractional Brownian persistent behavior (ii) a pattern associated with normal periods, which is characterized by a fractional Brownian anti-persistent behavior. Finally, we observe universality in the magnetic storm and earthquake dynamics, on a basis of a modified form of the Gutenberg-Richter law for the Tsallis statistics. This finding suggests a common approach to the interpretation of both phenomena in terms of the same driving physical mechanism. Signatures of discrete scale invariance in Dst time series further supports the aforementioned proposal.

  17. Large Volume, Optical and Opto-Mechanical Metrology Techniques for ISIM on JWST

    Science.gov (United States)

    Hadjimichael, Theo

    2015-01-01

    The final, flight build of the Integrated Science Instrument Module (ISIM) element of the James Webb Space Telescope is the culmination of years of work across many disciplines and partners. This paper covers the large volume, ambient, optical and opto-mechanical metrology techniques used to verify the mechanical integration of the flight instruments in ISIM, including optical pupil alignment. We present an overview of ISIM's integration and test program, which is in progress, with an emphasis on alignment and optical performance verification. This work is performed at NASA Goddard Space Flight Center, in close collaboration with the European Space Agency, the Canadian Space Agency, and the Mid-Infrared Instrument European Consortium.

  18. MECHANISMS OF BIOELECTRIC ACTIVITY IN ELECTRIC TISSUE

    Science.gov (United States)

    Altamirano, Mario; Coates, Christopher W.; Grundfest, Harry; Nachmansohn, David

    1953-01-01

    1. A preparation is described consisting of one or several layers of innervated cells of the electric organ of Electrophorus electricus. 2. Each plaque is multiply innervated and only at its caudal face. The nerve fibers may derive from two or more different nerve trunks. 3. During activity the innervated face becomes negative relative to the non-innervated. 4. The first electrical response of the cell to an increasing neural volley is graded and has the character of a prepotential. At a critical size of the prepotential the cell discharges with an all-or-nothing spike. 5. Both responses have durations of about 2 msec. 6. A neural volley which does not cause the spike discharge facilitates the discharge of the cell by a second subsequent volley in the same nerve (temporal facilitation). 7. The period of facilitation lasts ca. 900 msec. During the first 100 msec., the facilitation is large enough to cause a spike. In the later portion only the prepotential is facilitated. No electrical concomitant has been detected. 8. Neural volleys reaching the plaque from different trunks interact at the cell to produce a period of facilitation lasting only about 2 msec. This interaction is interpreted as spatial summation. 9. In a population of cells, simultaneous stimulation of 2 nerves causes a smaller discharge than the sum of the two isolated responses (occlusion). 10. Cells denervated for 7 weeks or more can be excited directly, but only by a current flow outward through the caudal face. 11. Weak direct stimulation causes a prepotential in the denervated plaque. On increasing the stimulus the prepotential increases to a critical size when a spike develops. The duration of both responses is about 2 msec. 12. The absolutely refractory period of the denervated cell is about 1.5 msec. and relative refractoriness lasts about 15 msec. 13. Direct stimulation causes slight facilitation lasting as long as 200 msec. 14. Repetitive stimulation of the nerve at low frequencies (2 to 3

  19. Engineering molecular mechanics: an efficient static high temperature molecular simulation technique.

    Science.gov (United States)

    Subramaniyan, Arun K; Sun, C T

    2008-07-16

    Inspired by the need for an efficient molecular simulation technique, we have developed engineering molecular mechanics (EMM) as an alternative molecular simulation technique to model high temperature (T>0 K) phenomena. EMM simulations are significantly more computationally efficient than conventional techniques such as molecular dynamics simulations. The advantage of EMM is achieved by converting the dynamic atomistic system at high temperature (T>0 K) into an equivalent static system. Fundamentals of the EMM methodology are derived using thermal expansion to modify the interatomic potential. Temperature dependent interatomic potentials are developed to account for the temperature effect. The efficiency of EMM simulations is demonstrated by simulating the temperature dependence of elastic constants of copper and nickel and the thermal stress developed in a confined copper system.

  20. Ultrasound assisted extraction of food and natural products. Mechanisms, techniques, combinations, protocols and applications. A review.

    Science.gov (United States)

    Chemat, Farid; Rombaut, Natacha; Sicaire, Anne-Gaëlle; Meullemiestre, Alice; Fabiano-Tixier, Anne-Sylvie; Abert-Vian, Maryline

    2017-01-01

    This review presents a complete picture of current knowledge on ultrasound-assisted extraction (UAE) in food ingredients and products, nutraceutics, cosmetic, pharmaceutical and bioenergy applications. It provides the necessary theoretical background and some details about extraction by ultrasound, the techniques and their combinations, the mechanisms (fragmentation, erosion, capillarity, detexturation, and sonoporation), applications from laboratory to industry, security, and environmental impacts. In addition, the ultrasound extraction procedures and the important parameters influencing its performance are also included, together with the advantages and the drawbacks of each UAE techniques. Ultrasound-assisted extraction is a research topic, which affects several fields of modern plant-based chemistry. All the reported applications have shown that ultrasound-assisted extraction is a green and economically viable alternative to conventional techniques for food and natural products. The main benefits are decrease of extraction and processing time, the amount of energy and solvents used, unit operations, and CO2 emissions.

  1. Usefulness of the Pain Tracking Technique in Acute Mechanical Low Back Pain

    Science.gov (United States)

    Bravo Acosta, Tania; Martín Cordero, Jorge E.; Hernández Tápanes, Solangel; Pedroso Morales, Isis; Fernández Cuesta, José Ignacio; Leyva Serrano, Maritza

    2015-01-01

    Objective. To evaluate the usefulness of the pain tracking technique in acute mechanical low back pain. Method. We performed an experimental prospective (longitudinal) explanatory study between January 2011 and September 2012. The sample was randomly divided into two groups. Patients were assessed at the start and end of the treatment using the visual analogue scale and the Waddell test. Treatment consisted in applying the pain tracking technique to the study group and interferential current therapy to the control group. At the end of treatment, cryotherapy was applied for 10 minutes. The Wilcoxon signed-rank test and the Mann Whitney test were used. They were performed with a predetermined significance level of p ≤ 0.05. Results. Pain was triggered by prolonged static posture and intense physical labor and intensified through trunk movements and when sitting and standing. The greatest relief was reported in lateral decubitus position and in William's position. The majority of the patients had contracture. Pain and disability were modified with the rehabilitation treatment in both groups. Conclusions. Both the pain tracking and interferential current techniques combined with cryotherapy are useful treatments for acute mechanical low back pain. The onset of analgesia is faster when using the pain tracking technique. PMID:26240758

  2. Usefulness of the Pain Tracking Technique in Acute Mechanical Low Back Pain

    Directory of Open Access Journals (Sweden)

    Tania Bravo Acosta

    2015-01-01

    Full Text Available Objective. To evaluate the usefulness of the pain tracking technique in acute mechanical low back pain. Method. We performed an experimental prospective (longitudinal explanatory study between January 2011 and September 2012. The sample was randomly divided into two groups. Patients were assessed at the start and end of the treatment using the visual analogue scale and the Waddell test. Treatment consisted in applying the pain tracking technique to the study group and interferential current therapy to the control group. At the end of treatment, cryotherapy was applied for 10 minutes. The Wilcoxon signed-rank test and the Mann Whitney test were used. They were performed with a predetermined significance level of p≤0.05. Results. Pain was triggered by prolonged static posture and intense physical labor and intensified through trunk movements and when sitting and standing. The greatest relief was reported in lateral decubitus position and in William’s position. The majority of the patients had contracture. Pain and disability were modified with the rehabilitation treatment in both groups. Conclusions. Both the pain tracking and interferential current techniques combined with cryotherapy are useful treatments for acute mechanical low back pain. The onset of analgesia is faster when using the pain tracking technique.

  3. Mechanical Activation of Construction Binder Materials by Various Mills

    Science.gov (United States)

    Fediuk, R. S.

    2016-04-01

    The paper deals with the mechanical grinding down to the nano powder of construction materials. During mechanical activation a composite binder active molecules cement minerals occur in the destruction of the molecular defects in the areas of packaging and breaking metastable phase decompensation intermolecular forces. The process is accompanied by a change in the kinetics of hardening of portland cement. Mechanical processes during grinding mineral materials cause, along with the increase in their surface energy, increase the Gibbs energy of powders and, respectively, their chemical activity, which also contributes to the high adhesion strength when contacting them with binders. Thus, the set of measures for mechanical activation makes better use of the weight of components filled with cement systems and adjust their properties. At relatively low cost is possible to provide a spectacular and, importantly, easily repeatable results in a production environment.

  4. Study of the mechanical properties of CeO{sub 2} layers with the nanoindentation technique

    Energy Technology Data Exchange (ETDEWEB)

    Roa, J.J., E-mail: joanjosep_roa@ub.ed [Centro DIOPMA, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Quimica, Universidad de Barcelona, C/Marti i Franques, 1, 08028, Barcelona (Spain); Gilioli, E.; Bissoli, F.; Pattini, F.; Rampino, S. [IMEM-CNR, Area delle Scienze 37/A, 43010 Fontanini-Parma (Italy); Capdevila, X.G.; Segarra, M. [Centro DIOPMA, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Quimica, Universidad de Barcelona, C/Marti i Franques, 1, 08028, Barcelona (Spain)

    2009-11-02

    The mechanical properties of CeO{sub 2} layers that are undoped or doped with other elements (e.g. Zr and Ta) are a topic of special interest specially in the manufacturing of superconductor buffer layers by pulsed electron deposition. Nowadays, the trend is to produce small devices (i.e. coated conductors), and the correct mechanical characterization is critical. In this sense, nanoindentation is a powerful technique widely employed to determine the mechanical properties of small volumes. In this study, the nanoindentation technique allow us determine the hardness (H) and Young's modulus (E) by sharp indentation of different buffer layers to explore the deposition process of CeO{sub 2} that is undoped or doped with Zr and Ta, and deposited on Ni-5%W at room temperature. This study was carried out on various samples at different ranges of applied loads (from 0.5 to 500 mN). Scanning electron microscopy images show no cracking for CeO{sub 2} doped with Zr, as the doping agent increases the toughness fracture of the CeO{sub 2} layer. This system, presents better mechanical stability than the other studied systems. Thus, the H for Zr-CeO{sub 2} is around 2.75 . 10{sup 6} Pa, and the elastic modulus calculated using the Bec et al. and Rar et al. models equals 249 . 10{sup 6} Pa and 235 . 10{sup 6} Pa respectively.

  5. Anesthesia Technique and Outcomes of Mechanical Thrombectomy in Patients With Acute Ischemic Stroke.

    Science.gov (United States)

    Bekelis, Kimon; Missios, Symeon; MacKenzie, Todd A; Tjoumakaris, Stavropoula; Jabbour, Pascal

    2017-02-01

    The impact of anesthesia technique on the outcomes of mechanical thrombectomy for acute ischemic stroke remains an issue of debate. We investigated the association of general anesthesia with outcomes in patients undergoing mechanical thrombectomy for ischemic stroke. We performed a cohort study involving patients undergoing mechanical thrombectomy for ischemic stroke from 2009 to 2013, who were registered in the New York Statewide Planning and Research Cooperative System database. An instrumental variable (hospital rate of general anesthesia) analysis was used to simulate the effects of randomization and investigate the association of anesthesia technique with case-fatality and length of stay. Among 1174 patients, 441 (37.6%) underwent general anesthesia and 733 (62.4%) underwent conscious sedation. Using an instrumental variable analysis, we identified that general anesthesia was associated with a 6.4% increased case-fatality (95% confidence interval, 1.9%-11.0%) and 8.4 days longer length of stay (95% confidence interval, 2.9-14.0) in comparison to conscious sedation. This corresponded to 15 patients needing to be treated with conscious sedation to prevent 1 death. Our results were robust in sensitivity analysis with mixed effects regression and propensity score-adjusted regression models. Using a comprehensive all-payer cohort of acute ischemic stroke patients undergoing mechanical thrombectomy in New York State, we identified an association of general anesthesia with increased case-fatality and length of stay. These considerations should be taken into account when standardizing acute stroke care. © 2017 American Heart Association, Inc.

  6. Mechanical, dielectric and optical assessment of glass composites prepared using milling technique

    Indian Academy of Sciences (India)

    Gurbinder Kaur; G Pickrell; V Kumar; O P Pandey; K Singh; S K Arya

    2015-08-01

    In the present investigation, mechanical and spectroscopic properties of glass composites have been investigated. The glass composites have been prepared by the milling technique instead of using any filler particle. Due to the presence of different alkaline earth modifiers in composites, marked difference in their strength and optical properties is observed. The band gap, Urbach energy and the extinction coefficient of the glass composites have been calculated using UV–visible spectroscopy. Moreover, the real and imaginary dielectric constants have also been calculated for all the composites in addition to the Weibull statistics and cumulative probability of failure. The results have been discussed in light of comparison between the glass composites and the individual glasses. The mechanical and optical properties indicate marked effect on the mechanical strength, band gap and Urbach energy for glass composites as compared with the individual glasses.

  7. Damage and deterioration mechanism and curing technique of concrete structure in main coal cleaning plants

    Institute of Scientific and Technical Information of China (English)

    LV Heng-lin; ZHAO Cheng-ming; SONG Lei; MA Ying; XU Chun-hua

    2009-01-01

    Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Da-tun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the spe-cial natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.

  8. Mechanisms of nerve capping technique in prevention of painful neuroma formation.

    Directory of Open Access Journals (Sweden)

    Hede Yan

    Full Text Available Nerve capping techniques have been introduced as a promising treatment modality for the treatment of painful neuroma with varied outcomes; however, its exact mechanism is still unknown. RhoA is one of the members of the RAS superfamily of GTPases that operate as molecular switches and plays an important role in peripheral nerve regeneration. Our aim was to investigate the structural and morphologic mechanisms by which the nerve capping technique prevents the formation of painful neuromas after neuroectomy. We also hoped to provide a theoretical basis for this treatment approach. An aligned nanofiber conduit was used for the capping procedure and the sciatic nerve of Sprague-Dawley rats was selected as the animal model. Behavioral analysis, extent of neuroma formation, histological assessment, expressions of pain markers of substance P and c-fos, molecular biological changes as well as ultrastructural features were investigated and compared with the findings in a no-capping control group. The formation of traumatic neuromas was significantly inhibited in the capping group with relatively "normal" structural and morphological features and no occurrence of autotomy and significantly lower expression of pain markers compared to the no-capping group. The gene expression of RhoA was consistently in a higher level in the capping group within 8 weeks after surgery. This study shows that capping technique will alter the regeneration state of transected nerves and reduce painful neuroma formation, indicating a promising approach for the treatment of painful neuroma. The initiation of the "regenerative brake" induced by structural as well as morphological improvements in the severed nerve is theorized to be most likely a key mechanism for the capping technique in the prevention of painful neuroma formation.

  9. Cough augmentation techniques for extubation or weaning critically ill patients from mechanical ventilation.

    Science.gov (United States)

    Rose, Louise; Adhikari, Neill Kj; Leasa, David; Fergusson, Dean A; McKim, Douglas

    2017-01-11

    There are various reasons why weaning and extubation failure occur, but ineffective cough and secretion retention can play a significant role. Cough augmentation techniques, such as lung volume recruitment or manually- and mechanically-assisted cough, are used to prevent and manage respiratory complications associated with chronic conditions, particularly neuromuscular disease, and may improve short- and long-term outcomes for people with acute respiratory failure. However, the role of cough augmentation to facilitate extubation and prevent post-extubation respiratory failure is unclear. Our primary objective was to determine extubation success using cough augmentation techniques compared to no cough augmentation for critically-ill adults and children with acute respiratory failure admitted to a high-intensity care setting capable of managing mechanically-ventilated people (such as an intensive care unit, specialized weaning centre, respiratory intermediate care unit, or high-dependency unit).Secondary objectives were to determine the effect of cough augmentation techniques on reintubation, weaning success, mechanical ventilation and weaning duration, length of stay (high-intensity care setting and hospital), pneumonia, tracheostomy placement and tracheostomy decannulation, and mortality (high-intensity care setting, hospital, and after hospital discharge). We evaluated harms associated with use of cough augmentation techniques when applied via an artificial airway (or non-invasive mask once extubated/decannulated), including haemodynamic compromise, arrhythmias, pneumothorax, haemoptysis, and mucus plugging requiring airway change and the type of person (such as those with neuromuscular disorders or weakness and spinal cord injury) for whom these techniques may be efficacious. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 4, 2016), MEDLINE (OvidSP) (1946 to April 2016), Embase (OvidSP) (1980 to April 2016), CINAHL (EBSCOhost) (1982

  10. Adsorption mechanisms and the effect of oxytetracycline on activated sludge.

    Science.gov (United States)

    Song, Xiancai; Liu, Dongfang; Zhang, Guowei; Frigon, Matthew; Meng, Xianrong; Li, Kexun

    2014-01-01

    The adsorption mechanisms and the effect of Oxytetracycline (OTC) onto activated sludge were studied. The results show that the adsorption of Oxytetracycline (OTC) onto activated sludge was coincident with the Langmuir, Freundlich and Temkin isotherm models. The Freundlich model had the best fit which suggested that chemical adsorption mechanism was dominant. The influences including pH and metal ions on the OTC were examined. It was demonstrated that the adsorption process was highly pH-dependant, which indicate that cationic exchange mechanisms may play an important role in the adsorption process. Na(+), K(+), Ca(2+), Mg(2+) and Cd(2+) ions more or less inhibited the adsorption of OTC on activated sludge while Cu(2+) enhanced the adsorption ability. The phenomenon may reflect the result that a surface complexation mechanism could involved in the adsorption. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Tractor Mechanics: Learning Activity Packages 1-19.

    Science.gov (United States)

    Clemson Univ., SC. Vocational Education Media Center.

    Learning activity packages are presented for teaching tractor mechanics. The first of two sections deals with miscellaneous tasks and contains learning activity packages on cleaning the tractor and receiving new tractor parts. Section 2 is concerned with maintaining and servicing the electrical system, and it includes the following learning…

  12. Gait models and mechanical energy in three cross-country skiing techniques.

    Science.gov (United States)

    Pellegrini, Barbara; Zoppirolli, Chiara; Bortolan, Lorenzo; Zamparo, Paola; Schena, Federico

    2014-11-01

    Fluctuations in mechanical energy of the body center of mass (COM) have been widely analyzed when investigating different gaits in human and animal locomotion. We applied this approach to estimate the mechanical work in cross-country skiing and to identify the fundamental mechanisms of this particular form of locomotion. We acquired movements of body segments, skis, poles and plantar pressures for eight skiers while they roller skied on a treadmill at 14 km h(-1) and a 2 deg slope using three different techniques (diagonal stride, DS; double poling, DP; double poling with kick, DK). The work associated with kinetic energy (KE) changes of COM was not different between techniques; the work against gravity associated with potential energy (PE) changes was higher for DP than for DK and was lowest for DS. Mechanical work against the external environment was 0.87 J m(-1) kg(-1) for DS, 0.70 J m(-1) kg(-1) for DP and 0.79 J m(-1) kg(-1) for DK. The work done to overcome frictional forces, which is negligible in walking and running, was 17.8%, 32.3% and 24.8% of external mechanical work for DS, DP and DK, respectively. The pendulum-like recovery (R%) between PE and KE was ~45%, ~26% and ~9% for DP, DK and DS, respectively, but energy losses by friction are not accounted for in this computation. The pattern of fluctuations of PE and KE indicates that DS can be described as a 'grounded running', where aerial phases are substituted by ski gliding phases, DP can be described as a pendular gait, whereas DK is a combination of both.

  13. Core competency in mechanical ventilation: development of educational objectives using the Delphi technique.

    Science.gov (United States)

    Goligher, Ewan C; Ferguson, Niall D; Kenny, Lisa P

    2012-10-01

    We sought to identify and standardize the core clinical knowledge and skills required to care for patients receiving mechanical ventilation. Prospective survey reaching consensus by the Delphi technique. North American survey conducted anonymously by electronic e-mail. International experts in mechanical ventilation, frontline resident educators, medical education experts, and community intensivists were recruited to participate Fourteen panelists participated (ten content experts, three resident educators, one medical education expert, zero community intensivists). Individual panelists generated a total of 200 educational objectives, of which 109 were duplicates. Of the remaining 91 items, 56 met predefined consensus criteria for inclusion in the final set of educational objectives. The educational objectives spanned a broad range of categories, including respiratory physiology, noninvasive ventilation, lung protective ventilation, weaning, and withholding and withdrawing mechanical ventilation. Agreement among panelists on the items included was high (median proportion supporting item inclusion was 88%, range 70%-100%). There is a consensus that general resident core competency in mechanical ventilation requires a broad range of knowledge application and skill. These educational objectives may help identify and standardize the educational outcomes related to mechanical ventilation that residents should achieve.

  14. Effect of aging on mechanical properties of 6063 Al-alloy using instrumented ball indentation technique

    Energy Technology Data Exchange (ETDEWEB)

    Das, G.; Das, Mousumi; Ghosh, Sabita; Dubey, Paritosh [Materials Science and Technology Division, National Metallurgical Laboratory (CSIR), PO-Burmamines, Jamshedpur 831007 (India); Ray, A.K., E-mail: asokroy@nmlindia.org [Materials Science and Technology Division, National Metallurgical Laboratory (CSIR), PO-Burmamines, Jamshedpur 831007 (India)

    2010-03-15

    One of the most important issues of standard conventional test methods for determining mechanical properties of ductile materials is that the requirement of test materials should be adequate and it cannot be applied to in-service components. Therefore, in this study, an instrumented ball indentation technique has been applied to determine a few mechanical properties of a 6063 Al alloy in order to establish a correlation between microstructure and its mechanical properties. The as-received 6063 alloy sample was in cast and homogenized condition. It was solutionized at 520 deg. C with two aging treatments. It was found that solutionized material with subsequent aging at 220 deg. C for 3 h does not produce any noticeable variation in mechanical properties. Whereas, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) on solutionized samples after 7 h aging at 220 deg. C of the same material revealed precipitation of sub-micron size (of the order of 60 nm) Mg{sub 2}Si phase and this subsequently resulted in variation in the mechanical properties of the alloy.

  15. Photoelasticity and DIC as optical techniques for monitoring masonry specimens under mechanical loads

    Science.gov (United States)

    Colla, C.; Gabrielli, E.

    2017-01-01

    To evaluate the complex behaviour of masonry structures under mechanical loads, numerical models are developed and continuously implemented at diverse scales, whilst, from an experimental viewpoint, laboratory standard mechanical tests are usually carried out by instrumenting the specimens via traditional measuring devices. Extracted values collected in the few points where the tools were installed are assumed to represent the behaviour of the whole specimen but this may be quite optimistic or approximate. Optical monitoring techniques may help in overcoming some of these limitations by providing full-field visualization of mechanical parameters. Photoelasticity and the more recent DIC, employed to monitor masonry columns during compression tests are here presented and a lab case study is compared listing procedures, data acquisitions, advantages and limitations. It is shown that the information recorded by traditional measuring tools must be considered limited to the specific instrumented points. Instead, DIC in particular among the optical techniques, is proving both a very precise global and local picture of the masonry performance, opening new horizons towards a deeper knowledge of this complex construction material. The applicability of an innovative DIC procedure to cultural heritage constructions is also discussed.

  16. Influence of different processing techniques on the mechanical properties of used tires in embankment construction.

    Science.gov (United States)

    Edinçliler, Ayşe; Baykal, Gökhan; Saygili, Altug

    2010-06-01

    Use of the processed used tires in embankment construction is becoming an accepted way of beneficially recycling scrap tires due to shortages of natural mineral resources and increasing waste disposal costs. Using these used tires in construction requires an awareness of the properties and the limitations associated with their use. The main objective of this paper is to assess the different processing techniques on the mechanical properties of used tires-sand mixtures to improve the engineering properties of the available soil. In the first part, a literature study on the mechanical properties of the processed used tires such as tire shreds, tire chips, tire buffings and their mixtures with sand are summarized. In the second part, large-scale direct shear tests are performed to evaluate shear strength of tire crumb-sand mixtures where information is not readily available in the literature. The test results with tire crumb were compared with the other processed used tire-sand mixtures. Sand-used tire mixtures have higher shear strength than that of the sand alone and the shear strength parameters depend on the processing conditions of used tires. Three factors are found to significantly affect the mechanical properties: normal stress, processing techniques, and the used tire content.

  17. Computational modelling of the mechanics of trabecular bone and marrow using fluid structure interaction techniques.

    Science.gov (United States)

    Birmingham, E; Grogan, J A; Niebur, G L; McNamara, L M; McHugh, P E

    2013-04-01

    Bone marrow found within the porous structure of trabecular bone provides a specialized environment for numerous cell types, including mesenchymal stem cells (MSCs). Studies have sought to characterize the mechanical environment imposed on MSCs, however, a particular challenge is that marrow displays the characteristics of a fluid, while surrounded by bone that is subject to deformation, and previous experimental and computational studies have been unable to fully capture the resulting complex mechanical environment. The objective of this study was to develop a fluid structure interaction (FSI) model of trabecular bone and marrow to predict the mechanical environment of MSCs in vivo and to examine how this environment changes during osteoporosis. An idealized repeating unit was used to compare FSI techniques to a computational fluid dynamics only approach. These techniques were used to determine the effect of lower bone mass and different marrow viscosities, representative of osteoporosis, on the shear stress generated within bone marrow. Results report that shear stresses generated within bone marrow under physiological loading conditions are within the range known to stimulate a mechanobiological response in MSCs in vitro. Additionally, lower bone mass leads to an increase in the shear stress generated within the marrow, while a decrease in bone marrow viscosity reduces this generated shear stress.

  18. Mechanisms of Non-canonical Activation of Ataxia Telangiectasia Mutated.

    Science.gov (United States)

    Khoronenkova, S V

    2016-12-01

    ATM is a master regulator of the cellular response to DNA damage. The classical mechanism of ATM activation involves its monomerization in response to DNA double-strand breaks, resulting in ATM-dependent phosphorylation of more than a thousand substrates required for cell cycle progression, DNA repair, and apoptosis. Here, new experimental evidence for non-canonical mechanisms of ATM activation in response to stimuli distinct from DNA double-strand breaks is discussed. It includes cytoskeletal changes, chromatin modifications, RNA-DNA hybrids, and DNA single-strand breaks. Noncanonical ATM activation may be important for the pathology of the multisystemic disease Ataxia Telangiectasia.

  19. Sulfuric acid leaching of mechanically activated manganese carbonate ore

    Directory of Open Access Journals (Sweden)

    Kenan Yıldız

    2010-06-01

    Full Text Available Acidic leaching of mechanically activated manganese ore from Denizli – Tavas was investigated. The ore was activated mechanically in a planetary mill and the amorphisation in manganese structure was analyzed with X-ray diffraction. The parameters in acidic leaching of the ore were milling time, acid concentration and time. All experiments were performed at 25°C with solid to liquid ratio: 1/10. The activation procedure led to amorphization and structural disordering in manganese ore and accelerated the dissolution of manganese in acidic media.

  20. Ultrasound Imaging Techniques for Spatiotemporal Characterization of Composition, Microstructure, and Mechanical Properties in Tissue Engineering.

    Science.gov (United States)

    Deng, Cheri X; Hong, Xiaowei; Stegemann, Jan P

    2016-08-01

    Ultrasound techniques are increasingly being used to quantitatively characterize both native and engineered tissues. This review provides an overview and selected examples of the main techniques used in these applications. Grayscale imaging has been used to characterize extracellular matrix deposition, and quantitative ultrasound imaging based on the integrated backscatter coefficient has been applied to estimating cell concentrations and matrix morphology in tissue engineering. Spectral analysis has been employed to characterize the concentration and spatial distribution of mineral particles in a construct, as well as to monitor mineral deposition by cells over time. Ultrasound techniques have also been used to measure the mechanical properties of native and engineered tissues. Conventional ultrasound elasticity imaging and acoustic radiation force imaging have been applied to detect regions of altered stiffness within tissues. Sonorheometry and monitoring of steady-state excitation and recovery have been used to characterize viscoelastic properties of tissue using a single transducer to both deform and image the sample. Dual-mode ultrasound elastography uses separate ultrasound transducers to produce a more potent deformation force to microscale characterization of viscoelasticity of hydrogel constructs. These ultrasound-based techniques have high potential to impact the field of tissue engineering as they are further developed and their range of applications expands.

  1. Structural and mechanical properties of welded joints of reduced activation martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Filacchioni, G. E-mail: gianni.filacchioni@casaccia.enea.it; Montanari, R.; Tata, M.E.; Pilloni, L

    2002-12-01

    Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program.

  2. Bridge Maintenance Robotic Arm:Mechanical Technique to Reduce the Nozzle Force of a Sandblastine Rig

    Institute of Scientific and Technical Information of China (English)

    Nathan Kirchner; Gavin Paul; D.K. Liu

    2006-01-01

    This paper describes a mechanical technique to reduce the nozzle reaction force of a sandblasting rig. A theoretical evaluation of the magnitudes and direction of action of typical sandblasting nozzle forces has been conducted and a technique for exploiting available energy in order to reduce the magnitude of the forces at the nozzle has been developed.Experimental results from a variety of tests in different configurations have confirmed the theoretically determined force magnitude's accuracy and shown that forces of up to 106N can be present in typical sandblasting operations. The results have also shown that an up to 77% reduction of force at the nozzle can be achieved by applying the developed mechanicaltechnique.

  3. Carbothermal reduction kinetics of mechanically activated chromite with graphite

    OpenAIRE

    Kenan Yıldız

    2011-01-01

    The carbothermal reduction kinetics of mechanically activated chromite with graphite under an argon atmosphere was investigated at temperatures between 1100 and 1400°C. Zhuravlev-Lesokhin-Tempelman (ZLT) method was used in the reduction kinetics for non-activated chromite and the activation energy was calculated as 401.7 kJ/mol. Solid-state diffusion method was used in the reduction kinetics for 60 min-activated chromite and the activation energy was calculated as 283.3 kJ/mol. This decrease ...

  4. An effective technique for isolating adult activated Schwann cells

    Institute of Scientific and Technical Information of China (English)

    Jifei Zhang; Lianhong Jin; Yuzhen Zhao

    2006-01-01

    BACKGROUND: Schwann cells (SCs) are neuroglial cells of peripheral nerve and play a key role in repairing peripheral nerve injury; therefore, it provides an important evidence for transplantation of SCs which are characterized by active proliferation and adult high-purity in vitro after nerve injury in clinic, and also develops a new therapeutic way for nerve injury.OBJECTIVE: To investigate an effective technique for isolating adult activated Schwann cells.DESIGN: Controlled observational study.SETTING: Mudanjiang Medical College.MATERIALS: The experiment was completed at the Department of Medical Genetics of Harbin Medical University from March 2003 to April 2005. Health female Wistar rats, aged 2 months, weighting 150-160 g, were randomly divided into 3 groups with 5 in each group.METHODS: The right sciatic nerves from 15 Wistar rats were exposed and transected at the mid thigh under pentobarbital anesthesia (4 mg/kg, I.p). Seven days later, the distal segments of the predegenerated nerves were removed and used to produce adult Schwann cell cultures. The distal segment of the predegenerated nerve, 20 mm in length, was resected. The nerve was cut into pieces 1 mm in length and incubated for 3 hours under CO2 at 37 ℃ with an enzyme mixture of 0.05% collagenase/dispase. Rats were divided into 3 groups:① Group 1: The nerve fragments were explanted in poly-L-lysine and laminin-coated dishes with BS medium from the 1st to the 6th day. On the 6th day, the fragments were removed into a new poly-L-lysine-laminin-coated dish and the BS medium was changed to BS with 10% FBS. The nerve fragments were replaced repeatedly in the same way in new dishes on the 12th and the 18th days. ②Group 2: For the first 3 days, the nerve fragments were fed with BS with 10% FBS. This medium was changed to BS medium on the third day. The nerve fragments were removed to another dish on day 6 and BS medium was changed to BS with 25 mL/L FBS. Hereafter the culture method was the same as

  5. Study on indium leaching from mechanically activated hard zinc residue

    Directory of Open Access Journals (Sweden)

    Yao J.H.

    2011-01-01

    Full Text Available In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x1/3]2=kt and (1-2x/3-(1-x2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled and 11.65 kJ/mol (activated within the temperature range of 30°C to 90°C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

  6. Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

    Directory of Open Access Journals (Sweden)

    Yun Lu

    2015-07-01

    Full Text Available This review presents the latest results of studies directed at photocatalyst coatings of titanium dioxide (TiO2 prepared by mechanical coating technique (MCT and its application. Compared with traditional coating techniques, MCT is a simple, low cost and useful coating formation process, which is proposed and developed based on mechanical frictional wear and impacts between substrate materials and metal powder particles in the bowl of planetary ball mill. The formation process of the metal coatings in MCT includes four stages: The nucleation by adhesion, the formation and coalescence of discrete islands, formation and thickening of continuous coatings, exfoliation of continuous coatings. Further, two-step MCT was developed based on the MCT concept for preparing composite coatings on alumina (Al2O3 balls. This review also discusses the influence on the fabrication of photocatalyst coatings after MCT and improvement of its photocatalytic activity: oxidation conditions, coating materials, melt salt treatment. In this review, the oxidation conditions had been studied on the oxidation temperature of 573 K, 673 K, 773 K, 873 K, 973 K, 1173 K and 1273 K, the oxidation time of 0.5 h, 1 h, 3 h, 10 h, 15 h, 20 h, 30 h, 40 h, and 50 h. The photocatalyst coatings showed the highest photocatalytic activity with the oxidation condition of 1073 K for 15 h. The metal powder of Ti, Ni and Cr had been used as the coating materials. The composite metal powder could affect the surface structure and photocatalytic activity. On the other hand, the melt salt treatment with KNO3 is an effective method to form the nano-size structure and enhance photocatalytic activity, especially under visible light.

  7. Mechanical state assessment using lamb wave technique in static tensile tests

    Science.gov (United States)

    Burkov, M. V.; Shah, R. T.; Eremin, A. V.; Byakov, A. V.; Panin, S. V.

    2016-11-01

    The paper deals with the investigation of Lamb wave ultrasonic technique for damage (or mechanical state) evaluation of AA7068T3 specimens in the course of tensile testing. Two piezoelectric transducers (PZT), one of which is used as an actuator and the other as sensor, were adhesively bonded on the specimen surface using epoxy. Two frequencies of testing signals (60 kHz and 350 kHz) were used. The set of static tensile tests were performed. The recorded signals were processed to calculate the informative parameters in order to evaluate the changes in stress-strain state of the specimens and their microstructure.

  8. Lifetimes of organic photovoltaics: Combining chemical and physical characterisation techniques to study degradation mechanisms

    DEFF Research Database (Denmark)

    Norrman, K.; Larsen, N.B.; Krebs, Frederik C

    2006-01-01

    Degradation mechanisms of a photovoltaic device with an Al/C-60/C-12-PSV/PEDOT:PSS/ITO/glass geometry was studied using a combination of in-plane physical and chemical analysis techniques: TOF-SIMS, AFM, SEM, interference microscopy and fluorescence microscopy. A comparison was made between...... a device being stored in darkness in air and a device that had been subjected to illumination under simulated sunlight (1000 Wm(-2), AM1.5) in air. It was found that oxygen diffuses through pinholes in the aluminium electrode. If stored in air in the dark the oxidation is limited to the C-60 layer...

  9. Experimental approach and techniques for the evaluation of wet flue gas desulfurization scrubber fluid mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Strock, T.W. [Babcock and Wilcox Co., Alliance, OH (United States). Research and Development Div.; Gohara, W.F. [Babcock and Wilcox Co., Barberton, OH (United States)

    1994-12-01

    The fluid mechanics within wet flue desulfurization (FGD) scrubbers involve several complex two-phase gas/liquid interactions. The fluid flow directly affects scrubber pressure drop, mist eliminator water removal, and the SO{sub 2} mass transfer/chemical reaction process. Current industrial efforts to develop cost-effective high-efficiency wet FGD scrubbers are focusing, in part, on optimizing the fluid mechanics. The development of an experimental approach and test facility for understanding and optimizing wet scrubber flow characteristics is discussed in this paper. Specifically, scaling procedures for downsizing a wet scrubber for the laboratory environment with field data comparisons are summarized. Furthermore, experimental techniques for the measurement of wet scrubber flow distribution, pressure drop, spray nozzle droplet size characteristics and wet scrubber liquid-to-gas ratio are discussed. Finally, the characteristics and capabilities of a new hydraulic test facility for wet FGD scrubbers are presented. (author)

  10. Identification of the mechanical behaviour of biopolymer composites using multistart optimisation technique

    KAUST Repository

    Brahim, Elhacen

    2013-10-01

    This paper aims at identifying the mechanical behaviour of starch-zein composites as a function of zein content using a novel optimisation technique. Starting from bending experiments, force-deflection response is used to derive adequate mechanical parameters representing the elastic-plastic behaviour of the studied material. For such a purpose, a finite element model is developed accounting for a simple hardening rule, namely isotropic hardening model. A deterministic optimisation strategy is implemented to provide rapid matching between parameters of the constitutive law and the observed behaviour. Results are discussed based on the robustness of the numerical approach and predicted tendencies with regards to the role of zein content. © 2013 Elsevier Ltd.

  11. Experimental analysis of mechanical response of stabilized occipitocervical junction by 3D mark tracking technique

    Directory of Open Access Journals (Sweden)

    Brémand F.

    2010-06-01

    Full Text Available This study is about a biomechanical comparison of some stabilization solutions for the occipitocervical junction. Four kinds of occipito-cervical fixations are analysed in this work: lateral plates fixed by two kinds of screws, lateral plates fixed by hooks and median plate. To study mechanical rigidity of each one, tests have been performed on human skulls by applying loadings and by studying mechanical response of fixations and bone. For this experimental analysis, a specific setup has been developed to impose a load corresponding to the flexion-extension physiological movements. 3D mark tracking technique is employed to measure 3D displacement fields on the bone and on the fixations. Observations of displacement evolution on the bone according to the fixation show different rigidities given by each solution.

  12. Experimental analysis of mechanical response of stabilized occipitocervical junction by 3D mark tracking technique

    Science.gov (United States)

    Germaneau, A.; Doumalin, P.; Dupré, J. C.; Brèque, C.; Brémand, F.; D'Houtaud, S.; Rigoard, P.

    2010-06-01

    This study is about a biomechanical comparison of some stabilization solutions for the occipitocervical junction. Four kinds of occipito-cervical fixations are analysed in this work: lateral plates fixed by two kinds of screws, lateral plates fixed by hooks and median plate. To study mechanical rigidity of each one, tests have been performed on human skulls by applying loadings and by studying mechanical response of fixations and bone. For this experimental analysis, a specific setup has been developed to impose a load corresponding to the flexion-extension physiological movements. 3D mark tracking technique is employed to measure 3D displacement fields on the bone and on the fixations. Observations of displacement evolution on the bone according to the fixation show different rigidities given by each solution.

  13. Revealing −1 Programmed Ribosomal Frameshifting Mechanisms by Single-Molecule Techniques and Computational Methods

    Directory of Open Access Journals (Sweden)

    Kai-Chun Chang

    2012-01-01

    Full Text Available Programmed ribosomal frameshifting (PRF serves as an intrinsic translational regulation mechanism employed by some viruses to control the ratio between structural and enzymatic proteins. Most viral mRNAs which use PRF adapt an H-type pseudoknot to stimulate −1 PRF. The relationship between the thermodynamic stability and the frameshifting efficiency of pseudoknots has not been fully understood. Recently, single-molecule force spectroscopy has revealed that the frequency of −1 PRF correlates with the unwinding forces required for disrupting pseudoknots, and that some of the unwinding work dissipates irreversibly due to the torsional restraint of pseudoknots. Complementary to single-molecule techniques, computational modeling provides insights into global motions of the ribosome, whose structural transitions during frameshifting have not yet been elucidated in atomic detail. Taken together, recent advances in biophysical tools may help to develop antiviral therapies that target the ubiquitous −1 PRF mechanism among viruses.

  14. Mechanical characterization of TiO{sub 2} nanofibers produced by different electrospinning techniques

    Energy Technology Data Exchange (ETDEWEB)

    Vahtrus, Mikk [Institute of Physics, University of Tartu, Ravila 14c, 50412 Tartu (Estonia); Šutka, Andris [Institute of Physics, University of Tartu, Ravila 14c, 50412 Tartu (Estonia); Institute of Silicate Materials, Riga Technical University, P. Valdena 3/7, Riga LV-1048 (Latvia); Institute of Technical Physics, Riga Technical University, P. Valdena 3, Riga LV-1048 (Latvia); Vlassov, Sergei, E-mail: vlassovs@ut.ee [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Šutka, Anna [Institute of Textile Technology and Design, Riga Technical University, Riga LV-1048 (Latvia); Laboratory of Biomass Eco-Efficient Conversation, Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga LV-1006 (Latvia); Polyakov, Boris [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Saar, Rando; Dorogin, Leonid; Lõhmus, Rünno [Institute of Physics, University of Tartu, Ravila 14c, 50412 Tartu (Estonia); Materials Technologies Competence Centre, Riia 185b, 51014 Tartu (Estonia)

    2015-02-15

    In this work TiO{sub 2} nanofibers produced by needle and needleless electrospinning processes from the same precursor were characterized and compared using Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and in situ SEM nanomechanical testing. Phase composition, morphology, Young's modulus and bending strength values were found. Weibull statistics was used to evaluate and compare uniformity of mechanical properties of nanofibers produced by two different methods. It is shown that both methods yield nanofibers with very similar properties. - Graphical abstract: Display Omitted - Highlights: • TiO{sub 2} nanofibers were produced by needle and needleless electrospinning processes. • Structure was studied by Raman spectroscopy and electron microscopy methods. • Mechanical properties were measured using advanced in situ SEM cantilevered beam bending technique. • Both methods yield nanofibers with very similar properties.

  15. Fabrication of Al–TiC composites by hot consolidation technique: its microstructure and mechanical properties

    Directory of Open Access Journals (Sweden)

    Sangita Mohapatra

    2016-04-01

    Full Text Available Al-based metal matrix composites reinforced with different volume fraction of TiC particles as reinforcement was synthesized by the hot consolidation process. The titanium carbide used in this study was synthesized directly from the titanium ore (ilmenite, FeTiO3 by carbothermic reduction process through thermal plasma technique. The field emission scanning electron micrographs (FESEM reveals the homogeneous distribution of TiC particles in the Al-matrix. Enhanced Young's modulus and mechanical properties with appreciable ductility were observed in the composite samples. The significant increases in the mechanical properties of the composites demonstrate the effectiveness of the low-density TiC reinforcement.

  16. Application of thermal analysis techniques in activated carbon production

    Science.gov (United States)

    Donnals, G.L.; DeBarr, J.A.; Rostam-Abadi, M.; Lizzio, A.A.; Brady, T.A.

    1996-01-01

    Thermal analysis techniques have been used at the ISGS as an aid in the development and characterization of carbon adsorbents. Promising adsorbents from fly ash, tires, and Illinois coals have been produced for various applications. Process conditions determined in the preparation of gram quantities of carbons were used as guides in the preparation of larger samples. TG techniques developed to characterize the carbon adsorbents included the measurement of the kinetics of SO2 adsorption, the performance of rapid proximate analyses, and the determination of equilibrium methane adsorption capacities. Thermal regeneration of carbons was assessed by TG to predict the life cycle of carbon adsorbents in different applications. TPD was used to determine the nature of surface functional groups and their effect on a carbon's adsorption properties.

  17. Influence of mechanical activation on synthesis of zinc metatitanate

    Directory of Open Access Journals (Sweden)

    Labus Nebojša J.

    2005-01-01

    Full Text Available Investigations of a ZnO-TiO2 binary oxide mixture during mechanical treatment were mainly focused on obtaining orthotitanate Zn2TiO4 with a spinel structure. Due to the specific way of energy transfer during mechanical treatment using a high-energy ball mill, the system passes through low temperature ZnTiO3 metatitanate phase formation. Mechanical activation was performed on an equimolar ratio mixture of ZnO and TiO2. The anatase phase was previously submitted to heat treatment for achieving a starting mixture rich in a rutile phase. Milling conditions were preset for observing the formation of a low temperature ZnTiO3 phase with a perovskite structure. The powder microstructure was characterized using scanning electron microscopy. A nitrogen gas sorption analyzer with the BET method was used to determine the specific surface area and porosity, indicating changes of powder sample properties during mechanical activation. Also, X ray powder diffractometry was applied to obtain the phase composition. Powders were then pressed into pellets and their compressibility was observed through density changes. According to microstructures obtained by scanning electron microscopy analysis, the system underwent a primary and secondary agglomeration process. Specific surface area measurements supported that conclusion. Compressibility investigations established the difference between compressibility of the non-activated mixture and activated powders. X-ray diffraction analysis revealed that a perovskite structure forms simultaneously with a spinel phase during the process of mechanical activation.

  18. Mathematical analysis techniques for modeling the space network activities

    Science.gov (United States)

    Foster, Lisa M.

    1992-01-01

    The objective of the present work was to explore and identify mathematical analysis techniques, and in particular, the use of linear programming. This topic was then applied to the Tracking and Data Relay Satellite System (TDRSS) in order to understand the space network better. Finally, a small scale version of the system was modeled, variables were identified, data was gathered, and comparisons were made between actual and theoretical data.

  19. Determining the stress field in active volcanoes using focal mechanisms

    Directory of Open Access Journals (Sweden)

    Bruno Massa

    2016-11-01

    Full Text Available Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs, Campi Flegrei (217 FPSs and Long Valley Caldera (38,000 FPSs. The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  20. Determining the stress field in active volcanoes using focal mechanisms

    Science.gov (United States)

    Massa, Bruno; D'Auria, Luca; Cristiano, Elena; De Matteo, Ada

    2016-11-01

    Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs), Campi Flegrei (217 FPSs) and Long Valley Caldera (38,000 FPSs). The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  1. A novel optical coherence tomography-based micro-indentation technique for mechanical characterization of hydrogels.

    Science.gov (United States)

    Yang, Ying; Bagnaninchi, Pierre O; Ahearne, Mark; Wang, Ruikang K; Liu, Kuo-Kang

    2007-12-22

    Depth-sensing micro-indentation has been well recognized as a powerful tool for characterizing mechanical properties of solid materials due to its non-destructive approach. Based on the depth-sensing principle, we have developed a new indentation method combined with a high-resolution imaging technique, optical coherence tomography, which can accurately measure the deformation of hydrogels under a spherical indenter at constant force. The Hertz contact theory has been applied for quantitatively correlating the indentation force and the deformation with the mechanical properties of the materials. Young's moduli of hydrogels estimated by the new method are comparable with those measured by conventional depth-sensing micro-indentation. The advantages of this new method include its capability to characterize mechanical properties of bulk soft materials and amenability to perform creeping tests. More importantly, the measurement can be performed under sterile conditions allowing non-destructive, in situ and real-time investigations on the changes in mechanical properties of soft materials (e.g. hydrogel). This unique character can be applied for various biomechanical investigations such as monitoring reconstruction of engineered tissues.

  2. High efficiency and simple technique for controlling mechanisms by EMG signals

    Science.gov (United States)

    Dugarte, N.; Álvarez, A.; Balacco, J.; Mercado, G.; Gonzalez, A.; Dugarte, E.; Javier, F.; Ceballos, G.; Olivares, A.

    2016-04-01

    This article reports the development of a simple and efficient system that allows control of mechanisms through electromyography (EMG) signals. The novelty about this instrument is focused on individual control of each motion vector mechanism through independent electronic circuits. Each of electronic circuit does positions a motor according to intensity of EMG signal captured. This action defines movement in one mechanical axis considered from an initial point, based on increased muscle tension. The final displacement of mechanism depends on individual’s ability to handle the levels of muscle tension at different body parts. This is the design of a robotic arm where each degree of freedom is handled with a specific microcontroller that responds to signals taken from a defined muscle. The biophysical interaction between the person and the final positioning of the robotic arm is used as feedback. Preliminary tests showed that the control operates with minimal positioning error margins. The constant use of system with the same operator showed that the person adapts and progressively improves at control technique.

  3. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration

    Science.gov (United States)

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-01

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency.

  4. Cognit activation: a mechanism enabling temporal integration in working memory

    OpenAIRE

    Fuster, Joaquín M.; Bressler, Steven L.

    2012-01-01

    Working memory is critical to the integration of information across time in goal-directed behavior, reasoning and language, yet its neural substrate is unknown. Based on recent research, we propose a mechanism by which the brain can retain working memory for prospective use, thereby bridging time in the perception/action cycle. The essence of the mechanism is the activation of cognits, which consist of distributed, overlapping and interactive cortical networks that in the aggregate encode the...

  5. Understanding the mechanism of ionic gelation for synthesis of chitosan nanoparticles using qualitative techniques

    Directory of Open Access Journals (Sweden)

    Kunjachan Sijumon

    2010-01-01

    Full Text Available We focused on qualitatively exploring the basic mechanisms involved in the Ionic gelation (IG process, a method quite frequently used for synthesis of chitosan (CS microparticles (MPs and nanoparticles (NPs. We synthesized CS MPs and NPs using the Ionic gelation and microemulsion methods, and characterized the CS NPs and MPs at different stages of formulation using scanning electron microscopy (SEM and fluorescence microscopy. Fourier Transform Infrared (FTIR analysis was carried out to confirm effective cross-linking. Moreover, for the first time, we reported the mechanisms of IG technique for CS NP and MP synthesis with qualitative proof: (1 Complex formation of long chain oligomers with polyanions (long beaded structures (2 cleavages at weak sites on addition of acid (HCl (3 formation of CS NPs on chain scission. The versatility of IG for the synthesis of CS MPs and NPs was proved and compared with the microemulsion technique, thereby enhancing the wide spectrum of its use in therapeutics and biomedical applications.

  6. The mechanical and tribological properties of UHMWPE loaded ALN after mechanical activation for joint replacements.

    Science.gov (United States)

    Gong, Kemeng; Qu, Shuxin; Liu, Yumei; Wang, Jing; Zhang, Yongchao; Jiang, Chongxi; Shen, Ru

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements.

  7. First stages of silicon oxidation with the activation relaxation technique

    Science.gov (United States)

    Ganster, Patrick; Béland, Laurent Karim; Mousseau, Normand

    2012-08-01

    Using the art nouveau method, we study the initial stages of silicon oxide formation. After validating the method's parameters with the characterization of point defects diffusion mechanisms in pure Stillinger-Weber silicon, which allows us to recover some known results and to detail vacancy and self-interstitial diffusion paths, the method is applied onto a system composed of an oxygen layer deposited on a silicon substrate. We observe the oxygen atoms as they move rapidly into the substrate. From these art nouveau simulations, we extract the energy barriers of elementary mechanisms involving oxygen atoms and leading to the formation of an amorphouslike silicon oxide. We show that the kinetics of formation can be understood in terms of the energy barriers between various coordination environments.

  8. Corrosion Inhibition Mechanism of Rare Earth Metal on LC4 Al Alloy with Spilt Cell Technique

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new method of studying the corrosion inhibition mechanism of rare earth metal(REM) on LC4 Al alloy with the spilt cell technique was studied. The principle and experimental method of the spilt cell technique were analyzed. By measuring the change of net-electric current between the two electrodes caused by the change of the amount of oxygen in the solution and the addition of CeCl3, the influence of corrosive performance of CeCl3 on LC4 super-power aluminum alloy in the 0.1 mol*L-1 NaCl solution was investigated. Meanwhile, the conditional changes of pH values, CeCl3 solution, additire and time of performance were also studied. Finally, the features of electrode surface were revealed by using SEM and X-ray energy-dispersive spectrometry (EDS). By combining these with other electric chemical techniques, such as potential-time curve, polarization curve et al.

  9. Small molecules reveal an alternative mechanism of Bax activation.

    Science.gov (United States)

    Brahmbhatt, Hetal; Uehling, David; Al-Awar, Rima; Leber, Brian; Andrews, David

    2016-04-15

    The pro-apoptotic protein Bax commits a cell to death by permeabilizing the mitochondrial outer membrane (MOM). To obtain small-molecule probes for elucidating the molecular mechanism(s) of Bax activation, we screened for compounds that induced Bax-mediated liposome permeabilization. We identified five structurally different small molecules that promoted both Bax targeting to and oligomerization at membranes. All five compounds initiated Bax oligomerization in the absence of membranes by a mechanism unlike Bax activation by Bcl-2 homology 3 domain (BH3) proteins. Some of the compounds induced Bax/Bak-dependent apoptosis in cells. Activation of Bax by the most active compound was poorly inhibited by the anti-apoptotic protein Bcl-XL and requires a cysteine residue at position 126 of Bax that is not required for activation by BH3 proteins. Our results reveal a novel pathway for Bax activation independent of pro-apoptotic BH3 proteins that may have important implications for the regulation of Bax activity in cells. © 2016 The Author(s).

  10. Measurement uncertainty on subsurface defects detection using active infrared thermographic technique

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Yoon Jae; Kim [Kongju National University, Cheonan (Korea, Republic of); Choi, Won Jae [Center for Safety Measurements, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2015-10-15

    Active infrared thermography methods have been known to possess good fault detection capabilities for the detection of defects in materials compared to the conventional passive thermal infrared imaging techniques. However, the reliability of the technique has been under scrutiny. This paper proposes the lock-in thermography technique for the detection and estimation of artificial subsurface defect size and depth with uncertainty measurement.

  11. A comparison between active and passive techniques for measurements of radon emanation factors

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Coto, I. [Dept. Fisica Aplicada, University of Huelva, Huelva (Spain)], E-mail: Israel.lopez@dfa.uhu.es; Mas, J.L. [Dept. de Fisica Aplicada I, E.U.P., University of Seville, Seville (Spain); San Miguel, E.G.; Bolivar, J.P. [Dept. Fisica Aplicada, University of Huelva, Huelva (Spain); Sengupta, D. [Department of Geology and Geophysics, I.I.T. Kharagpur, West Bengal (India)

    2009-05-15

    Some radon related parameters have been determined through two different techniques (passive and active) in soil and phosphogypsum samples. Emanation factors determined through these techniques show a good agreement for soil samples while for phosphogympsum samples appear large discrepancies. In this paper, these discrepancies are analyzed and explained if non-controlled radon leakages in the passive technique are taken into account.

  12. Mechanisms of Ca2+-dependent calcineurin activation in mechanical stretch-induced hypertrophy.

    Science.gov (United States)

    Zobel, Carsten; Rana, Obaida R; Saygili, Erol; Bölck, Birgit; Saygili, Esra; Diedrichs, Holger; Reuter, Hannes; Frank, Konrad; Müller-Ehmsen, Jochen; Pfitzer, Gabriele; Schwinger, Robert H G

    2007-01-01

    Pressure overload is the major stimulus for cardiac hypertrophy. Accumulating evidence suggests an important role for calcium-induced activation of calcineurin in mediating hypertrophic signaling. Hypertrophy is an important risk factor for cardiovascular morbidity and mortality. We therefore employed an in vitro mechanical stretch model of cultured neonatal cardiomyocytes to evaluate proposed mechanisms of calcium-induced calcineurin activation in terms of inhibition of calcineurin activity and hypertrophy. The protein/DNA ratio and ANP gene expression were used as markers for stretch-induced hypertrophy. Stretch increased the calcineurin activity, MCIP1 gene expression and DNA binding of NFATc as well as the protein/DNA ratio and ANP mRNA in a significant manner. The specific inhibitor of calcineurin, cyclosporin A, inhibited the stretch-induced increase in calcineurin activity, MCIP1 gene expression and hypertrophy. The L-type Ca2+ channel blocker nifedipine and a blocker of the Na+/H+ exchanger (cariporide) both suppressed stretch-dependent enhanced calcineurin activity and hypertrophy. Also application of a blocker of the Na+/Ca2+ exchanger (KB-R7943) was effective in preventing calcineurin activation and increases in the protein/DNA ratio. Inhibition of capacitative Ca2+ entry with SKF 96365 was also sufficient to abrogate calcineurin activation and hypertrophy. The blocker of stretch-activated ion channels, streptomycin, was without effect on stretch-induced hypertrophy and calcineurin activity. The present work suggests that of the proposed mechanisms for the calcium-induced activation of calcineurin (L-type Ca2+ channels, capacitative Ca2+ entry, Na+/H+ exchanger, Na+/Ca2+ exchanger and stretch-activated channels) all but stretch-activated channels are possible targets for the inhibition of hypertrophy. 2007 S. Karger AG, Basel

  13. Temperature dependence of rapidly adapting mechanically activated currents in rat dorsal root ganglion neurons.

    Science.gov (United States)

    Jia, Zhanfeng; Ling, Jennifer; Gu, Jianguo G

    2012-08-01

    Rapidly adapting mechanically activated channels (RA) are expressed on somatosensory neurons and thought to play a role in mechanical transduction. Because mechanical sensations can be significantly affected by temperatures, we examined thermal sensitivity of RA currents in cultured dorsal root ganglion (DRG) neurons to see if RA channel activity is highly temperature-dependent. RA currents were evoked from DRG neurons by membrane displacements and recorded by the whole-cell patch-clamp recording technique. We found that RA currents were significantly enhanced by warming temperatures from 22 to 32 °C and reduced by cooling temperatures from 24 to 14 °C. RA channel activation exhibited steep temperature-dependence with a large temperature coefficient (Q10>5) and a high activation energy (Ea>30 kcal/mol). We further showed that RA channel activation by mechanical stimulation led to membrane depolarization, which could result in action potential firing at 22 °C or 32 °C but not at 14 °C. Taken together, our results provide the measurements of thermal dynamics and activation energy of RA channels, and suggest that a high energy barrier is present for RA channels to open. These findings are in agreement with temperature sensitivity of mechanical sensations in mammals.

  14. The Antiviral Activities and Mechanisms of Marine Polysaccharides: An Overview

    Science.gov (United States)

    Wang, Wei; Wang, Shi-Xin; Guan, Hua-Shi

    2012-01-01

    Recently, the studies on the antiviral activities of marine natural products, especially marine polysaccharides, are attracting more and more attention all over the world. Marine-derived polysaccharides and their lower molecular weight oligosaccharide derivatives have been shown to possess a variety of antiviral activities. This paper will review the recent progress in research on the antiviral activities and the mechanisms of these polysaccharides obtained from marine organisms. In particular, it will provide an update on the antiviral actions of the sulfated polysaccharides derived from marine algae including carrageenans, alginates, and fucans, relating to their structure features and the structure–activity relationships. In addition, the recent findings on the different mechanisms of antiviral actions of marine polysaccharides and their potential for therapeutic application will also be summarized in detail. PMID:23235364

  15. The Antiviral Activities and Mechanisms of Marine Polysaccharides: An Overview

    Directory of Open Access Journals (Sweden)

    Hua-Shi Guan

    2012-12-01

    Full Text Available Recently, the studies on the antiviral activities of marine natural products, especially marine polysaccharides, are attracting more and more attention all over the world. Marine-derived polysaccharides and their lower molecular weight oligosaccharide derivatives have been shown to possess a variety of antiviral activities. This paper will review the recent progress in research on the antiviral activities and the mechanisms of these polysaccharides obtained from marine organisms. In particular, it will provide an update on the antiviral actions of the sulfated polysaccharides derived from marine algae including carrageenans, alginates, and fucans, relating to their structure features and the structure–activity relationships. In addition, the recent findings on the different mechanisms of antiviral actions of marine polysaccharides and their potential for therapeutic application will also be summarized in detail.

  16. Instrumental Neutron Activation Analysis Technique using Subsecond Radionuclides

    DEFF Research Database (Denmark)

    Nielsen, H.K.; Schmidt, J.O.

    1987-01-01

    The fast irradiation facility Mach-1 installed at the Danish DR 3 reactor has been used in boron determinations by means of Instrumental Neutron Activation Analysis using12B with 20-ms half-life. The performance characteristics of the system are presented and boron determinations of NBS standard...

  17. Techniques for active embodiment of participants in virtual environments

    Energy Technology Data Exchange (ETDEWEB)

    Hightower, R.; Stansfield, S.

    1996-03-01

    This paper presents preliminary work in the development of an avatar driver. An avatar is the graphical embodiment of a user in a virtual world. In applications such as small team, close quarters training and mission planning and rehearsal, it is important that the user`s avatar reproduce his or her motions naturally and with high fidelity. This paper presents a set of special purpose algorithms for driving the motion of the avatar with minimal information about the posture and position of the user. These algorithms utilize information about natural human motion and posture to produce solutions quickly and accurately without the need for complex general-purpose kinematics algorithms. Several examples illustrating the successful applications of these techniques are included.

  18. Deep evolutionary conservation of an intramolecular protein kinase activation mechanism.

    Directory of Open Access Journals (Sweden)

    Jingfen Han

    Full Text Available DYRK-family kinases employ an intramolecular mechanism to autophosphorylate a critical tyrosine residue in the activation loop. Once phosphorylated, DYRKs lose tyrosine kinase activity and function as serine/threonine kinases. DYRKs have been characterized in organisms from yeast to human; however, all entities belong to the Unikont supergroup, only one of five eukaryotic supergroups. To assess the evolutionary age and conservation of the DYRK intramolecular kinase-activation mechanism, we surveyed 21 genomes representing four of the five eukaryotic supergroups for the presence of DYRKs. We also analyzed the activation mechanism of the sole DYRK (class 2 DYRK present in Trypanosoma brucei (TbDYRK2, a member of the excavate supergroup and separated from Drosophila by ∼850 million years. Bioinformatics showed the DYRKs clustering into five known subfamilies, class 1, class 2, Yaks, HIPKs and Prp4s. Only class 2 DYRKs were present in all four supergroups. These diverse class 2 DYRKs also exhibited conservation of N-terminal NAPA regions located outside of the kinase domain, and were shown to have an essential role in activation loop autophosphorylation of Drosophila DmDYRK2. Class 2 TbDYRK2 required the activation loop tyrosine conserved in other DYRKs, the NAPA regions were critical for this autophosphorylation event, and the NAPA-regions of Trypanosoma and human DYRK2 complemented autophosphorylation by the kinase domain of DmDYRK2 in trans. Finally, sequential deletion analysis was used to further define the minimal region required for trans-complementation. Our analysis provides strong evidence that class 2 DYRKs were present in the primordial or root eukaryote, and suggest this subgroup may be the oldest, founding member of the DYRK family. The conservation of activation loop autophosphorylation demonstrates that kinase self-activation mechanisms are also primitive.

  19. Mechanisms of active control for noise inside a vibrating cylinder

    Science.gov (United States)

    Lester, Harold C.; Fuller, Chris R.

    1987-01-01

    The active control of propeller-induced noise fields inside a flexible cylinder is studied with attention given to the noise reduction mechanisms inherent in the present coupled acoustic shell model. The active noise control model consists of an infinitely long aluminum cylinder with a radius of 0.4 m and a thickness of 0.001 m. Pressure maps are shown when the two external sources are driven in-phase at a frequency corresponding to Omega = 0.22.

  20. DISTINCTION OF MECHANICALLY PROCESSED WOOD SURFACES WITH SIMILAR QUALITIES USING SUNSET LASER TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Anna Carolina de Almeida Andrade

    2016-06-01

    Full Text Available The ASTM D 1666-11 (2011 norm classifies the quality of wood surface pieces after its mechanical processing. Although this classification is difficult to achieve visually, the use of some tools, such as solid state laser, can facilitate this classification. The aim of this work was to evaluate the use of sunset laser to qualify mechanically processed surfaces with similar visual qualities. We used a log from the base of a Khaya ivorensis tree and one from a K. senegalensis tree, both 11 years old. 22 specimens of dimensions 600x140x30 mm (CxLxE were made of each species. The specimens were flattened with speeds of 2400, 3600 and 4000 min-1 and advanced speeds were predetermined in 6 and 15 m.min-1. Then the samples were illuminated with sunset laser and photographed at high resolution, the images were transferred to the software Image J. To evaluate the sunset laser, areas of defects in wood that are classified as regular and bad by ASTM D 1666-11 (2011 were used. There was a difference in classification of wood defects between the two methods used, from the 31 specimens classified as regularly by visual analysis, 8 of them were classified as bad by the laser method. The use of solid-state laser in the sunset laser technique was more efficient in evaluating small differences in mechanically processed wood defects compared to visual evaluation.

  1. The Effectiveness of Active and Traditional Teaching Techniques in the Orthopedic Assessment Laboratory

    Science.gov (United States)

    Nottingham, Sara; Verscheure, Susan

    2010-01-01

    Active learning is a teaching methodology with a focus on student-centered learning that engages students in the educational process. This study implemented active learning techniques in an orthopedic assessment laboratory, and the effects of these teaching techniques. Mean scores from written exams, practical exams, and final course evaluations…

  2. Figure Analysis: A Teaching Technique to Promote Visual Literacy and Active Learning

    Science.gov (United States)

    Wiles, Amy M.

    2016-01-01

    Learning often improves when active learning techniques are used in place of traditional lectures. For many of these techniques, however, students are expected to apply concepts that they have already grasped. A challenge, therefore, is how to incorporate active learning into the classroom of courses with heavy content, such as molecular-based…

  3. The Effectiveness of Active and Traditional Teaching Techniques in the Orthopedic Assessment Laboratory

    Science.gov (United States)

    Nottingham, Sara; Verscheure, Susan

    2010-01-01

    Active learning is a teaching methodology with a focus on student-centered learning that engages students in the educational process. This study implemented active learning techniques in an orthopedic assessment laboratory, and the effects of these teaching techniques. Mean scores from written exams, practical exams, and final course evaluations…

  4. Differential MSC activation leads to distinct mononuclear leukocyte binding mechanisms

    Science.gov (United States)

    Kota, Daniel J.; Dicarlo, Bryan; Hetz, Robert A.; Smith, Philippa; Cox, Charles S.; Olson, Scott D.

    2014-04-01

    Advances in the field of Multipotent Mesenchymal Stromal cell (MSC) biology have demonstrated that MSCs can improve disease outcome when `activated' to exert immunomodulatory effects. However, the precise mechanisms modulating MSC-immune cells interactions remain largely elusive. In here, we activated MSC based on a recent polarization paradigm, in which MSCs can be polarized towards a pro- or anti-inflammatory phenotype depending on the Toll-like receptor stimulated, to dissect the mechanisms through which MSCs physically interact with and modulate leukocytes in this context. Our data show that MSCs activated through the Toll-like receptor (TLR) 4 pathway increased VCAM-1 and ICAM-1 dependent binding of leukocytes. On the other hand, TLR3 stimulation strongly increases leukocytes affinity to MSC comparatively, through the formation of cable-like hyaluronic acid structures. In addition, TLR4 activation elicited secretion of pro-inflammatory mediators by MSCs, whereas TLR3-activated MSCs displayed a milder pro-inflammatory phenotype, similar to inactivated MSCs. However, the differently activated MSCs maintained their ability to suppress leukocyte activation at similar levels in our in vitro model, and this immunomodulatory property was shown here to be partially mediated by prostaglandin. These results reinforce the concept that alternate activation profiles control MSC responses and may impact the therapeutic use of MSCs.

  5. Successful Application of Active Learning Techniques to Introductory Microbiology

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Hoffman

    2009-12-01

    Full Text Available While the traditional lecture format may be a successful way to teach microbiology to both medical and nursing students, it was not an effective means of learning for many prenursing and preprofessional students enrolled in either of the introductory microbiology courses at Ashland Community College, an open enrollment institution. The structure of both Medical Microbiology and Principles of Microbiology was redesigned to allow students to address the material in an active manner. Daily quizzes, student group discussions, scrapbooks, lab project presentations and papers, and extra credit projects were all added in order to allow students maximum exposure to the course material in a manner compatible with various methods of learning. Student knowledge, course evaluations, and student success rates have all improved with the active learning format.

  6. New trends in the development of "active correlations" technique

    Science.gov (United States)

    Tsyganov, Yu. S.

    2016-09-01

    With reaching extremely high intensities of heavy-ion beams, new requirements for the detection system of the Dubna Gas-Filled Recoil Separator (DGFRS) will definitely be set. One of the challenges is how to apply the "active correlations" method [1-6] to suppress beam associated background products without significant losses in the whole long-term experiment efficiency value. Different scenarios and equations for the development of a method according to this requirement are under consideration in the present paper.

  7. Electrogastrography: A Noninvasive Technique to Evaluate Gastric Electrical Activity

    OpenAIRE

    Claudia P. Sanmiguel; Mintchev, Martin P.; Bowes, Kenneth L.

    1998-01-01

    Electrogastrography (EGG) is the recording of gastric electrical activity (GEA) from the body surface. The cutaneous signal is low in amplitude and consequently must be amplified considerably. The resultant signal is heavily contaminated with noise, and visual analysis alone of an EGG signal is inadequate. Consequently, EGG recordings require special methodology for acquisition, processing and analysis. Essential components of this methodology involve an adequate system of digital filtering, ...

  8. Aerial monitoring in active mud volcano by UAV technique

    Science.gov (United States)

    Pisciotta, Antonino; Capasso, Giorgio; Madonia, Paolo

    2016-04-01

    UAV photogrammetry opens various new applications in the close range domain, combining aerial and terrestrial photogrammetry, but also introduces low-cost alternatives to the classical manned aerial photogrammetry. Between 2014 and 2015 tree aerial surveys have been carried out. Using a quadrotor drone, equipped with a compact camera, it was possible to generate high resolution elevation models and orthoimages of The "Salinelle", an active mud volcanoes area, located in territory of Paternò (South Italy). The main risks are related to the damages produced by paroxysmal events. Mud volcanoes show different cyclic phases of activity, including catastrophic events and periods of relative quiescence characterized by moderate activity. Ejected materials often are a mud slurry of fine solids suspended in liquids which may include water and hydrocarbon fluids, the bulk of released gases are carbon dioxide, with some methane and nitrogen, usually pond-shaped of variable dimension (from centimeters to meters in diameter). The scope of the presented work is the performance evaluation of a UAV system that was built to rapidly and autonomously acquire mobile three-dimensional (3D) mapping data in a volcanic monitoring scenario.

  9. Alkali-activated cementitious materials: Mechanisms, microstructure and properties

    Science.gov (United States)

    Jiang, Weimin

    The goal of this study was to examine the activation reaction, microstructure, properties, identify the mechanisms of activation, and achieve an enhanced understanding of activation processes occurring during the synthesis of alkali activated cementitious materials (AAC). The discussions classify the following categories. (1) alkali activated slag cement; (2) alkali activated portland-slag cement; (3) alkali activated fly ash-slag cement; (4) alkali activated pozzolana-lime cement; (5) alkali activated pozzolana cement. The activators involved are NaOH, KOH; Nasb2SOsb4;\\ Nasb2COsb3;\\ CaSOsb4, and soluble silicate of sodium and potassium. The effect of alkali activation on the microstructure of these materials were analyzed at the micro-nanometer scale by SEM, EDS, ESEM, and TEM. Also sp{29}Si and sp{27}Al MAS-NMR, IR, Raman, TGA, and DTA were performed to characterize the phase in these systems. Slag, fly ash, silica fume, as well as blended cements containing mixtures of these and other components were characterized. A set of ordinary portland cement paste samples served as a control. This study confirmed that AAC materials have great potential because they could generate very early high strength, greater durability and high performance. Among the benefits to be derived from this research is a better understanding of the factors that control concrete properties when using AAC materials, and by controlling the chemistry and processing to produce desired microstructures and properties, as well as their durability.

  10. Kinetic mechanism of the activation of human plasminogen by streptokinase.

    Science.gov (United States)

    Kosow, D P

    1975-10-07

    A method of determining the initial rate of plasminogen activation has been developed. The method has been used to investigate the mechanism of activation of human plasminogen by streptokinase. Plasmin formation follows saturation kinetics. Inhibition of plasmin formation by epsilon-aminocaproic acid is uncompetitive with a Ki of 0.6 mM. A model consistent with the data is that streptokinase induces a conformational change in the plasminogen molecule, producing an active center which cleaves an internal peptide bond to produce plasmin. Thus, streptokinase functions as a catalytic allosteric effector.

  11. The mechanical properties of nanofilled resin-based composites: characterizing discrete filler particles and agglomerates using a micromanipulation technique.

    LENUS (Irish Health Repository)

    Curtis, Andrew R

    2009-02-01

    To assess the mechanical properties of discrete filler particles representative of several inorganic fillers in modern dental resin-based composites (RBCs) and to assess the validity of a novel micromanipulation technique.

  12. Insights into the Thiamine Diphosphate Enzyme Activation Mechanism: Computational Model for Transketolase Using a Quantum Mechanical/Molecular Mechanical Method.

    Science.gov (United States)

    Nauton, Lionel; Hélaine, Virgil; Théry, Vincent; Hecquet, Laurence

    2016-04-12

    We propose the first computational model for transketolase (TK), a thiamine diphosphate (ThDP)-dependent enzyme, using a quantum mechanical/molecular mechanical method on the basis of crystallographic TK structures from yeast and Escherichia coli, together with experimental kinetic data reported in the literature with wild-type and mutant TK. This model allowed us to define a new route for ThDP activation in the enzyme environment. We evidenced a strong interaction between ThDP and Glu418B of the TK active site, itself stabilized by Glu162A. The crucial point highlighted here is that deprotonation of ThDP C2 is not performed by ThDP N4' as reported in the literature, but by His481B, involving a HOH688A molecule bridge. Thus, ThDP N4' is converted from an amino form to an iminium form, ensuring the stabilization of the C2 carbanion or carbene. Finally, ThDP activation proceeds via an intermolecular process and not by an intramolecular one as reported in the literature. More generally, this proposed ThDP activation mechanism can be applied to some other ThDP-dependent enzymes and used to define the entire TK mechanism with donor and acceptor substrates more accurately.

  13. Active mechanics and geometry of adherent cells and cell colonies

    Science.gov (United States)

    Banerjee, Shiladitya

    2014-03-01

    Measurements of traction stresses exerted by adherent cells or cell colonies on elastic substrates have yielded new insight on how the mechanical and geometrical properties of the substrate regulate cellular force distribution, mechanical energy, spreading, morphology or stress ber architecture. We have developed a generic mechanical model of adherent cells as an active contractile gel mechanically coupled to an elastic substrate and to neighboring cells in a tissue. The contractile gel model accurately predicts the distribution of cellular and traction stresses as observed in single cell experiments, and captures the dependence of cell shape, traction stresses and stress ber polarization on the substrate's mechanical and geometrical properties. The model further predicts that the total strain energy of an adherent cell is solely regulated by its spread area, in agreement with recent experiments on micropatterned substrates with controlled geometry. When used to describe the behavior of colonies of adherent epithelial cells, the model demonstrates the crucial role of the mechanical cross-talk between intercellular and extracellular adhesion in regulating traction force distribution. Strong intercellular mechanical coupling organizes traction forces to the colony periphery, whereas weaker intercellular coupling leads to the build up of traction stresses at intercellular junctions. Furthermore, in agreement with experiments on large cohesive keratinocyte colonies, the model predicts a linear scaling of traction forces with the colony size. This scaling suggests the emergence of an effective surface tension as a scale-free material property of the adherent tissue, originating from actomyosin contractility.

  14. Predictions of precipitation reaction mechanisms for 7xxx series aluminum alloys cast by CDS technique

    Science.gov (United States)

    Sobrino, Luca

    The need to reduce the fleet fuel consumption is pushing the automotive industry to reduce vehicles weight. In this context high strength aluminum alloys are a viable alternative to the heavier steel currently adopted. In particular 7xxx series wrought alloys, thanks to their excellent strength to weight ratio, are drawing the attention of carmakers. The development of the Controlled Diffusion Solidification (CDS) technique allows now the casting of these alloys into near net shapes, thus reducing all the costs related to the manufacturing process and making them attractive. Because of the completely different microstructure resulting from the CDS process, a new design of the heat treatments is required to achieve the best mechanical properties. This project therefore evaluates the macro and microhardness evolution of CDS cast 7xxx alloys in T4 and T6 conditions to predict their precipitation sequence, thus providing useful information for the heat treatments design.

  15. Study of multilayer packaging delamination mechanisms using different surface analysis techniques

    Energy Technology Data Exchange (ETDEWEB)

    Garrido-Lopez, Alvaro [Department of Chemistry, University of La Rioja, C/Madre de Dios 51, E-26006 Logrono, La Rioja (Spain); Tena, Maria Teresa, E-mail: maria-teresa.tena@unirioja.es [Department of Chemistry, University of La Rioja, C/Madre de Dios 51, E-26006 Logrono, La Rioja (Spain)

    2010-04-01

    Multilayer packaging, consisting of different layers joined by using an adhesive or an extrusion process, is widely used to promote different products, such as food, cosmetics, etc. The main disadvantage in using this form of packaging is the delamination process. In this work, different surface techniques (X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy) are used to analyse the delaminated surfaces in order to study the mechanisms that cause delamination of multilayer packaging. According to our results, the reaction of migrated molecules with adhesive-aluminium bonds is the main cause of the chemical delamination process. In contrast, the delamination of extruded materials would seem to be caused by the breaking of Van der Waals bonds.

  16. Two major medicinal honeys have different mechanisms of bactericidal activity.

    Directory of Open Access Journals (Sweden)

    Paulus H S Kwakman

    Full Text Available Honey is increasingly valued for its antibacterial activity, but knowledge regarding the mechanism of action is still incomplete. We assessed the bactericidal activity and mechanism of action of Revamil® source (RS honey and manuka honey, the sources of two major medical-grade honeys. RS honey killed Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa within 2 hours, whereas manuka honey had such rapid activity only against B. subtilis. After 24 hours of incubation, both honeys killed all tested bacteria, including methicillin-resistant Staphylococcus aureus, but manuka honey retained activity up to higher dilutions than RS honey. Bee defensin-1 and H₂O₂ were the major factors involved in rapid bactericidal activity of RS honey. These factors were absent in manuka honey, but this honey contained 44-fold higher concentrations of methylglyoxal than RS honey. Methylglyoxal was a major bactericidal factor in manuka honey, but after neutralization of this compound manuka honey retained bactericidal activity due to several unknown factors. RS and manuka honey have highly distinct compositions of bactericidal factors, resulting in large differences in bactericidal activity.

  17. Platelet activation through a Bi-leaflet mechanical heart valve

    Science.gov (United States)

    Hedayat, Mohammadali; Borazjani, Iman

    2016-11-01

    Platelet activation is one of the major drawbacks of the Mechanical Heart Valves (MHVs) which can increase the risk of thrombus formation in patients. The platelet activation in MHVs can be due to the abnormal shear stress during the systole, the backward leakage flow during the diastole, and the flow through the hinge region. We investigate the contribution of each of the above mechanism to the activation of platelets in MHVs by performing simulations of the flow through the MHV and in the hinge region. The large scale heart valve simulations are performed in a straight aorta using a sharp interface curvilinear immersed boundary method along with a strong-coupling algorithm under physiological flow conditions. In addition, in order to perform the simulation of hinge region the flow field boundary conditions are obtained from the largescale simulations during a whole cardiac cycle. In order to investigate the role of hinge flow on platelet activation in MHVs, a 23mm St. Jude Medical Regent valve hinge with three different gap sizes is tested along with different platelet activation models to ensure the consistency of our results with different activation models. We compare the platelet activation of the hinge region against the bulk of the flow during one cardiac cycle. This work is supported by the American Heart Association Grant 13SDG17220022, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

  18. Activation mechanisms of natural killer cells during influenza virus infection.

    Directory of Open Access Journals (Sweden)

    Ilwoong Hwang

    Full Text Available During early viral infection, activation of natural killer (NK cells elicits the effector functions of target cell lysis and cytokine production. However, the cellular and molecular mechanisms leading to NK cell activation during viral infections are incompletely understood. In this study, using a model of acute viral infection, we investigated the mechanisms controlling cytotoxic activity and cytokine production in response to influenza (flu virus. Analysis of cytokine receptor deficient mice demonstrated that type I interferons (IFNs, but not IL-12 or IL-18, were critical for the NK cell expression of both IFN-γ and granzyme B in response to flu infection. Further, adoptive transfer experiments revealed that NK cell activation was mediated by type I IFNs acting directly on NK cells. Analysis of signal transduction molecules showed that during flu infection, STAT1 activation in NK cells was completely dependent on direct type I IFN signaling, whereas STAT4 activation was only partially dependent. In addition, granzyme B induction in NK cells was mediated by signaling primarily through STAT1, but not STAT4, while IFN-γ production was mediated by signaling through STAT4, but not STAT1. Therefore, our findings demonstrate the importance of direct action of type I IFNs on NK cells to mount effective NK cell responses in the context of flu infection and delineate NK cell signaling pathways responsible for controlling cytotoxic activity and cytokine production.

  19. Experimental techniques for screening of antiosteoporotic activity in postmenopausal osteoporosis.

    Science.gov (United States)

    Satpathy, Swaha; Patra, Arjun; Ahirwar, Bharti

    2015-12-01

    Postmenopausal osteoporosis, a silent epidemic, has become a major health hazard, afflicting about 50% of postmenopausal women worldwide and is thought to be a disease with one of the highest incidences in senile people. It is a chronic, progressive condition associated with micro-architectural deterioration of bone tissue that results in low bone mass, decreased bone strength that predisposes to an increased risk of fracture. Women are more likely to develop osteoporosis than men due to reduction in estrogen during menopause which leads to decline in bone formation and increase in bone resorption activity. Estrogen is able to suppress the production of proinflammatory cytokines like interleukin (IL)-1, IL-6, IL-7 and tumor necrosis factor (TNF-α). This is why these cytokines are elevated in postmenopausal women. In this review article we have made an attempt to collate the various methods and parameters most frequently used for screening of antiosteoporotic activity in postmenopausal osteoporosis. Pertaining to ovariectomized animal model, this is the most appropriate model for studying the efficacy of different drugs to prevent bone loss in postmenopausal osteoporosis.

  20. Evaluation of intrastromal corneal ring segments for treatment of keratoconus with a mechanical implantation technique

    Directory of Open Access Journals (Sweden)

    Zeki Tunc

    2013-01-01

    Full Text Available Purpose: To evaluate the clinical outcomes of intrastromal corneal ring segment (ICRS implantation in patients with keratoconus using a mechanical implantation technique. Materials and Methods: Thirty eyes of 17 patients with keratoconus were enrolled. ICRSs (Keraring were implanted after dissection of the tunnel using Tunc′s specially designed dissector under suction. A complete ophthalmic examination was performed, including uncorrected distance visual acuity (UDVA, corrected distance visual acuity (CDVA, spherical equivalent, keratometric readings, inferosuperior asymmetry index (ISAI, and ultrasound pachymetry. All 3-, 6-, and 12-month follow-ups were completed, and statistical analysis was performed. Results: The mean preoperative UDVA for all eyes was 1.36 ± 0.64 logMAR. At 12 months, the mean UDVA was 0.51 ± 0.28 logMAR (P = 0.001, and the mean preoperative CDVA was 0.57 ± 0.29 logMAR, which improved to 0.23 ± 0.18 (P = 0.001 at 1 year. There was a significant reduction in spherical equivalent refractive error from -6.42 ± 4.69 diopters (D preoperatively to -1.26 ± 1.45 D (P = 0.001 at 1 year. In the same period, the mean K-readings improved from 49.38 ± 3.72 D to 44.43 ± 3.13 D (P = 0.001, and the mean ISAI improved from 7.92 ± 3.12 to 4.21 ± 1.96 (P = 0.003. No significant changes in mean central corneal thickness were observed postoperatively. There were no major complications during and or after surgery. Conclusion: ICRS implantation using a unique mechanical dissection technique is a safe and effective treatment for keratoconus. All parameters improved by the 1-year follow-up.

  1. Effect of resination technique on mechanical properties of medium density fiberboard

    Directory of Open Access Journals (Sweden)

    Nadir Ayrilmis

    2013-02-01

    Full Text Available Effects of different resination techniques relative to the mechanical properties of commercially produced thick medium density fiberboard (MDF were investigated. The amount of urea-formaldehyde resin (11 wt% applied to the wood fibers was gradually decreased in the blowline (11, 10.5, 10, and 9.5 wt%, while it was gradually increased in the short-retention blender (0, 0.5, 1, and 1.5. wt%. The internal bond strength of the MDF boards considerably improved as the amount of the resin applied to the fibers in the short-retention blender was increased to 1.5 wt%. In particular, the increase in the IB strength was most pronounced as the resin content increased from 1 to 1.5%. The edge and face screw withdrawal resistances increased by 7.7 and 7.9% as the amount of the resin applied to the fibers in the blender was increased. Similar values were also observed for the flexural properties. Overall, the total resin content in the production of thick MDF can be decreased as blender resination, a means of post-dryer resin addition, is incorporated into the blowline resination technique.

  2. Monolithic active pixel radiation detector with shielding techniques

    Energy Technology Data Exchange (ETDEWEB)

    Deptuch, Grzegorz W.

    2016-09-06

    A monolithic active pixel radiation detector including a method of fabricating thereof. The disclosed radiation detector can include a substrate comprising a silicon layer upon which electronics are configured. A plurality of channels can be formed on the silicon layer, wherein the plurality of channels are connected to sources of signals located in a bulk part of the substrate, and wherein the signals flow through electrically conducting vias established in an isolation oxide on the substrate. One or more nested wells can be configured from the substrate, wherein the nested wells assist in collecting charge carriers released in interaction with radiation and wherein the nested wells further separate the electronics from the sensing portion of the detector substrate. The detector can also be configured according to a thick SOA method of fabrication.

  3. Monolithic active pixel radiation detector with shielding techniques

    Science.gov (United States)

    Deptuch, Grzegorz W.

    2016-09-06

    A monolithic active pixel radiation detector including a method of fabricating thereof. The disclosed radiation detector can include a substrate comprising a silicon layer upon which electronics are configured. A plurality of channels can be formed on the silicon layer, wherein the plurality of channels are connected to sources of signals located in a bulk part of the substrate, and wherein the signals flow through electrically conducting vias established in an isolation oxide on the substrate. One or more nested wells can be configured from the substrate, wherein the nested wells assist in collecting charge carriers released in interaction with radiation and wherein the nested wells further separate the electronics from the sensing portion of the detector substrate. The detector can also be configured according to a thick SOA method of fabrication.

  4. Chemical weapons detection by fast neutron activation analysis techniques

    Science.gov (United States)

    Bach, P.; Ma, J. L.; Froment, D.; Jaureguy, J. C.

    1993-06-01

    A neutron diagnostic experimental apparatus has been tested for nondestructive verification of sealed munitions. Designed to potentially satisfy a significant number of van-mobile requirements, this equipment is based on an easy to use industrial sealed tube neutron generator that interrogates the munitions of interest with 14 MeV neutrons. Gamma ray spectra are detected with a high purity germanium detector, especially shielded from neutrons and gamma ray background. A mobile shell holder has been used. Possible configurations allow the detection, in continuous or in pulsed modes, of gamma rays from neutron inelastic scattering, from thermal neutron capture, and from fast or thermal neutron activation. Tests on full scale sealed munitions with chemical simulants show that those with chlorine (old generation materials) are detectable in a few minutes, and those including phosphorus (new generation materials) in nearly the same time.

  5. Anisotropy of mechanical and thermal properties of AZ31 sheets prepared using the ARB technique

    Science.gov (United States)

    Halmešová, K.; Trojanová, Z.; Džugan, J.; Drozd, Z.; Minárik, P.; Knapek, M.

    2017-07-01

    In the accumulative roll bonding (ARB) technique, repeated stacking of material followed by conventional roll-bonding is carried out. For this process the surfaces are cleaned with ethanol and then joined together by rolling. The rolled material is then cut into two halves, again surface treated and roll-bonded. This process may be repeated several times. For the magnesium alloy AZ31 (Mg-3Al-1Zn) rolling at an elevated temperature of 400 °C is necessary for ARB because of the low plasticity of hexagonal magnesium alloys at lower temperatures. Samples for this study were prepared using 1 to 3 ARB passes through the rolling mill. It was found that the ARB substantially refined the grain size of sheets to the micrometer scale. The microstructure and texture of the deformed samples were studied by light and electron microscopy. The mechanical properties of the ARB samples were explored using tensile test-pieces cut from the sheets with the tensile axis taken either parallel or perpendicular to the rolling direction, where a significant anisotropy in both mechanical properties and Young’s modulus was found. Anisotropy is explained on the basis of the specific microstructure and texture formed during the ARB process.

  6. Neonatal total liquid ventilation: is low-frequency forced oscillation technique suitable for respiratory mechanics assessment?

    Science.gov (United States)

    Bossé, Dominick; Beaulieu, Alexandre; Avoine, Olivier; Micheau, Philippe; Praud, Jean-Paul; Walti, Hervé

    2010-08-01

    This study aimed to implement low-frequency forced oscillation technique (LFFOT) in neonatal total liquid ventilation (TLV) and to provide the first insight into respiratory impedance under this new modality of ventilation. Thirteen newborn lambs, weighing 2.5 + or - 0.4 kg (mean + or - SD), were premedicated, intubated, anesthetized, and then placed under TLV using a specially design liquid ventilator and a perfluorocarbon. The respiratory mechanics measurements protocol was started immediately after TLV initiation. Three blocks of measurements were first performed: one during initial respiratory system adaptation to TLV, followed by two other series during steady-state conditions. Lambs were then divided into two groups before undergoing another three blocks of measurements: the first group received a 10-min intravenous infusion of salbutamol (1.5 microg x kg(-1) x min(-1)) after continuous infusion of methacholine (9 microg x kg(-1) x min(-1)), while the second group of lambs was chest strapped. Respiratory impedance was measured using serial single-frequency tests at frequencies ranging between 0.05 and 2 Hz and then fitted with a constant-phase model. Harmonic test signals of 0.2 Hz were also launched every 10 min throughout the measurement protocol. Airway resistance and inertance were starkly increased in TLV compared with gas ventilation, with a resonant frequency ventilation. We show that LFFOT is an effective tool to track respiratory mechanics under TLV.

  7. Research on Cavitation Regions of Upstream Pumping Mechanical Seal Based on Dynamic Mesh Technique

    Directory of Open Access Journals (Sweden)

    Huilong Chen

    2014-08-01

    Full Text Available In order to study the cavitation area of the Upstream Pumping Mechanical Seal, three-dimensional microgap inner flow field of the Upstream Pumping Mechanical Seal was simulated with multiphase flow cavitation model and dynamic mesh technique based on hydrodynamic lubrication theory. Furthermore, the simulated result was compared with the experimental data. The results show that the simulated result with the Zwart-Gerber-Belamri cavitation model was much closer to the experimental data. The area of cavitation inception mainly occurred at the concave side of the spiral groove and surrounding region without spiral grooves, which was nearly covered by the inner diameter to roots of grooves; in addition, the region near the surface of the stationary ring was primary cavitation location. The area of cavitation has little relationship with the medium pressure; however, it became larger following increasing rotating speed in the range of researched operating conditions. Moreover the boundary of cavitated area was transformed from smooth to rough, which occurred in similar film thickness. When cavitation number was decreasing, which was conducive to improving the lubrication performance of sealed auxiliary, it made the sealing stability decline.

  8. Post-Heat Treatment and Mechanical Assessment of Polyvinyl Alcohol Nanofiber Sheet Fabricated by Electrospinning Technique

    Directory of Open Access Journals (Sweden)

    Mahir Es-saheb

    2014-01-01

    Full Text Available Polyvinyl alcohol (PVA sheets based nanofibers were produced by electrospinning technique. Postheat treatment of the produced PVA sheets with temperatures both below and above Tg to improve the mechanical properties of this material is conducted. The morphology, microstructures, and thermal degradation of the nanofibers sheets produced were investigated using scanning electron microscopy (SEM, transmission electron microscope (TEM, and thermal gravimetric analysis (TGA. Produced nanofibers are compact, and entangled with each other, with diameters from around 150 to 210. Some mechanical characteristics of the successfully produced PVA sheets, and heat-treated, are then conducted and assessed employing uniaxial tensile tests at different speeds ranging from 1 mm/min to 100 mm/min. The tensile test results obtained show that the PVA sheets are strain rate sensitive with increasing strength as the speed (i.e., strain rate increases. The yield tensile stress ranges from 2.411 to 6.981 MPa, the ductility (i.e., elongation percent from ∼21 to 60%, and Young modulus ranges from 103 to 0.137 KPa. However, for heat-treated samples, it is found that the yield strength increases almost by ∼35–40% more than the values of untreated cases with values reaching up to about 3.627–9.63 MPa.

  9. Complementary Physical and Mechanical Techniques to Characterise Tooth: A Bone-like Tissue

    Institute of Scientific and Technical Information of China (English)

    Peter Zioupos; Keith D. Rogers

    2006-01-01

    Bone like tissues are biocomposites comprising an organic matrix (mostly collagen) and a reinforcement phase in the form of mineral crystals (poorly stoichiometric apatite). The composite properties are a result of the material characteristics of the two phases, their interaction, the relative composition, the orientation and the micro-architecture of the structure. The inherent spatial heterogeneity of these tissues (a result of evolutionary and functional requirements) and their exposure to various environmental and mechanical influences result in highly variable properties on the microscale, which can only be characterised by modern microanalytical methods. We present here results obtained by the complementary use of the modern nanoindentation and micro-X-ray diffraction techniques, which were used to probe the properties and structure of human dentine and enamel of primary molar teeth. The results show that both the addition and the higher organization of mineral within the organic matrix produce stiffer and harder tissue and that the examination of properties within small tissue volumes can be reliably achieved by use of these two methods in parallel. This opens new avenues in the study of biomaterial in general, and for the local characterisation of regions of teeth that suffered bacterial attack, mechanical wear, fluoridisation, chemical bleaching, or dental treatment such as laser ablation or drilling.

  10. Class I Microcins: Their Structures, Activities, and Mechanisms of Resistance

    Science.gov (United States)

    Severinov, Konstantin; Semenova, Ekaterina; Kazakov, Teymur

    Microcin J25, microcin B17, and microcin C7-C51 are the three known members of class I posttranslationally modified microcins (heavily posttranslationally modified antibacterial peptides produced by Enterobacteriaceae with molecular weights of less than 5 kDa). The three microcins are unrelated to each other; they have structures that are highly atypical for ribosomally synthesized peptides and target essential molecular machines that are validated drug targets. In this chapter, available data on mechanisms of action, structure-activity relationships, and immunity mechanisms for class I microcins and related compounds are discussed.

  11. Src kinase conformational activation: thermodynamics, pathways, and mechanisms.

    Directory of Open Access Journals (Sweden)

    Sichun Yang

    2008-03-01

    Full Text Available Tyrosine kinases of the Src-family are large allosteric enzymes that play a key role in cellular signaling. Conversion of the kinase from an inactive to an active state is accompanied by substantial structural changes. Here, we construct a coarse-grained model of the catalytic domain incorporating experimental structures for the two stable states, and simulate the dynamics of conformational transitions in kinase activation. We explore the transition energy landscapes by constructing a structural network among clusters of conformations from the simulations. From the structural network, two major ensembles of pathways for the activation are identified. In the first transition pathway, we find a coordinated switching mechanism of interactions among the alphaC helix, the activation-loop, and the beta strands in the N-lobe of the catalytic domain. In a second pathway, the conformational change is coupled to a partial unfolding of the N-lobe region of the catalytic domain. We also characterize the switching mechanism for the alphaC helix and the activation-loop in detail. Finally, we test the performance of a Markov model and its ability to account for the structural kinetics in the context of Src conformational changes. Taken together, these results provide a broad framework for understanding the main features of the conformational transition taking place upon Src activation.

  12. Constrained optimization techniques for active control of aeroelastic response

    Science.gov (United States)

    Mukhopadhyay, Vivekananda

    1987-01-01

    Active control of aeroelastic response is a complex problem in which the designer usually tries to satisfy many design criteria which are often conflicting in nature. To further complicate the design problem, the state space equations describing this type of control problem are usually of high order, involving a large number of states to represent the flexible structure and unsteady aerodynamics. Control laws based on the standard Linear - Quadratic - Gaussian method are of the same high order as the aeroelastic plant and may be difficult to implement in the flight computer. To overcome this disadvantage a new approach was developed for designing low-order optimized robust control laws. In this approach, a nonlinear programming algorithm is used to search for the values of control law design variables that minimize a performance index while satisfying several inequality constraints that describe the design criteria on the stability robustness and responses. The method is applied to a gust load alleviation problem and a stability robustness improvement problem of a drone aircraft.

  13. Electrogastrography: A Noninvasive Technique to Evaluate Gastric Electrical Activity

    Directory of Open Access Journals (Sweden)

    Claudia P Sanmiguel

    1998-01-01

    Full Text Available Electrogastrography (EGG is the recording of gastric electrical activity (GEA from the body surface. The cutaneous signal is low in amplitude and consequently must be amplified considerably. The resultant signal is heavily contaminated with noise, and visual analysis alone of an EGG signal is inadequate. Consequently, EGG recordings require special methodology for acquisition, processing and analysis. Essential components of this methodology involve an adequate system of digital filtering, amplification and analysis, along with minimization of the sources of external noise (random motions of the patient, electrode-skin interface impedance, electrode bending, obesity, etc and a quantitative interpretation of the recordings. There is a close relationship between GEA and gastric motility. Although it has been demonstrated that EGG satisfactorily reflects internal GEA frequency, there is not acceptable correlation with gastric contractions or gastric emptying. Many attempts have been made to relate EGG 'abnormalities' with clinical syndromes and diseases; however, the diagnostic and clinical value of EGG is still very much in question.

  14. Mechanisms of virus resistance and antiviral activity of snake venoms

    Directory of Open Access Journals (Sweden)

    JVR Rivero

    2011-01-01

    Full Text Available Viruses depend on cell metabolism for their own propagation. The need to foster an intimate relationship with the host has resulted in the development of various strategies designed to help virus escape from the defense mechanisms present in the host. Over millions of years, the unremitting battle between pathogens and their hosts has led to changes in evolution of the immune system. Snake venoms are biological resources that have antiviral activity, hence substances of significant pharmacological value. The biodiversity in Brazil with respect to snakes is one of the richest on the planet; nevertheless, studies on the antiviral activity of venom from Brazilian snakes are scarce. The antiviral properties of snake venom appear as new promising therapeutic alternative against the defense mechanisms developed by viruses. In the current study, scientific papers published in recent years on the antiviral activity of venom from various species of snakes were reviewed. The objective of this review is to discuss the mechanisms of resistance developed by viruses and the components of snake venoms that present antiviral activity, particularly, enzymes, amino acids, peptides and proteins.

  15. THE STRESS IMPACT ON MECHANICAL PROPERTIES OF ROCKS IN HYDRO FRACTURING TECHNIQUE

    Directory of Open Access Journals (Sweden)

    B. GURUPRASAD

    2012-02-01

    Full Text Available Ground water is considered to be the best safe protected drinking water source and bore wells are drilled in hard crystalline rock terrains for drinking water, irrigation and industrial purposes. Even after scientific location, some bore wells yield inadequate quantity of water or fail to yield. The success of bore wells depend largely onnumber, length, dilation and interconnectivity of fractures encountered on drilling. Considering the cost factor involved in drilling a new bore well, rejuvenation of failed bore well through some technique is thought off. The innovative technology of ‘hydro fracturing’ is a new interdisciplinary approach of Hydro mechanical tostimulate the bore well to improve the yield by applying water pressure into bore well by using a heavy duty mechanical compressor. The hydro fracturing technique was first used in oil well to increase oil and gas production. In this research paper, the hydraulic pressure applied increases with depth reflecting the rigidness,toughness of rock. The fracture development, propagation of fracture and stress behavior depends on the physical and mechanical properties of rocks. The hydro fracturing process has been conducted in three depth zones ranging from 8 m to 45 m below ground level in Annavasal union of Pudukottai district, Tamil Nadu, India. The Pressure application varies depending on the geological formations. This study pertains to a part of research work. The minimum and maximum pressures applied are 1 and 10 N/mm2 respectively. The maximumpressure of 10 N/mm2 has been recorded in the third zone, where the country rock is charnockite which is generally massive, compact and dense rock. Generally for the igneous rock in the third zone in the depth range of 40 to 50 m, more than 7 N/mm2 of pressure has been applied indicating extremely strong nature with uniaxial compressive strength 100 – 300 N/mm2, tensile strength 7- 25 N/mm2. Out of 37 bore wells 32.4% of bore wells have shown

  16. Mechanical muscle fibre conduction velocity of the biceps as measured by a new seismic technique.

    Science.gov (United States)

    Journée, H L; de Jonge, A B; van Calker, R; Gräler, G

    1995-01-01

    A recently-developed technique, called seismic myography (SMG) has the characteristic of recording fast micro-mechanical response times. These times can be determined with sub-millisecond accuracy. The response times can be compared to response times of EMG recordings. The "muscular electro-seismic response" (MESR) latencies, due to direct electrical stimulation of the biceps muscle, are used for explorative measurements of the mechanical conduction velocity of the muscle fibres. The measurements are performed by means of a general-purpose physiological multimeter which is equiped with the micro-seismic function. Measurements are performed on two healthy subjects, aged 22 years. The MESR-latencies are measured along a medial and a lateral trajectory on their biceps muscles. The MESR-latencies at stimulus-cathodal to seismic transducer distances of 2,0-3,5 cm, are in the range of 2.0-3.8 ms, while at distances in the range of 7.5-8.9 cm the MESR-latencies varied between 3.4 and 4.7 ms. The calculated mechanical muscle fibre conduction velocities (MMFCV) are in the range between 36 and 89 m/s. There is a reproducability error of maximum 20%. The MMFCV's of the lateral and medial trajectory do not differ within the accuracy of the present method. However, the MMFCV's are considerably higher than the electrical muscle fibre conduction velocities of MUAPS ((E)MFCV). Some aspects of the MMFCV and possible consequences to surface EMG recordings are discussed. It is concluded that this seismic method for measuring MMFCV is a new accessible and simple to handle tool for the description of muscle function, and offers an interesting new contribution in experimental muscular research.

  17. Effects on hamstring muscle extensibility, muscle activity, and balance of different stretching techniques.

    Science.gov (United States)

    Lim, Kyoung-Il; Nam, Hyung-Chun; Jung, Kyoung-Sim

    2014-02-01

    [Purpose] The purpose of this study was to investigate the effects of two different stretching techniques on range of motion (ROM), muscle activation, and balance. [Subjects] For the present study, 48 adults with hamstring muscle tightness were recruited and randomly divided into three groups: a static stretching group (n=16), a PNF stretching group (n=16), a control group (n=16). [Methods] Both of the stretching techniques were applied to the hamstring once. Active knee extension angle, muscle activation during maximum voluntary isometric contraction (MVC), and static balance were measured before and after the application of each stretching technique. [Results] Both the static stretching and the PNF stretching groups showed significant increases in knee extension angle compared to the control group. However, there were no significant differences in muscle activation or balance between the groups. [Conclusion] Static stretching and PNF stretching techniques improved ROM without decrease in muscle activation, but neither of them exerted statistically significant effects on balance.

  18. Effects on Hamstring Muscle Extensibility, Muscle Activity, and Balance of Different Stretching Techniques

    Science.gov (United States)

    Lim, Kyoung-Il; Nam, Hyung-Chun; Jung, Kyoung-Sim

    2014-01-01

    [Purpose] The purpose of this study was to investigate the effects of two different stretching techniques on range of motion (ROM), muscle activation, and balance. [Subjects] For the present study, 48 adults with hamstring muscle tightness were recruited and randomly divided into three groups: a static stretching group (n=16), a PNF stretching group (n=16), a control group (n=16). [Methods] Both of the stretching techniques were applied to the hamstring once. Active knee extension angle, muscle activation during maximum voluntary isometric contraction (MVC), and static balance were measured before and after the application of each stretching technique. [Results] Both the static stretching and the PNF stretching groups showed significant increases in knee extension angle compared to the control group. However, there were no significant differences in muscle activation or balance between the groups. [Conclusion] Static stretching and PNF stretching techniques improved ROM without decrease in muscle activation, but neither of them exerted statistically significant effects on balance. PMID:24648633

  19. The Adsorption Mechanism of Modified Activated Carbon on Phenol

    Directory of Open Access Journals (Sweden)

    Lin J. Q.

    2016-01-01

    Full Text Available Modified activated carbon was prepared by thermal treatment at high temperature under nitrogen flow. The surface properties of the activated carbon were characterized by Boehm titration, BET and point of zero charge determination. The adsorption mechanism of phenol on modified activated carbon was explained and the adsorption capacity of modified activated carbon for phenol when compared to plain activated carbon was evaluated through the analysis of adsorption isotherms, thermodynamic and kinetic properties. Results shows that after modification the surface alkaline property and pHpzc value of the activated carbon increase and the surface oxygen-containing functional groups decrease. The adsorption processes of the plain and modified carbon fit with Langmuir isotherm equation well, and the maximum adsorption capacity increase from 123.46, 111.11, 103.09mg/g to 192.31, 178.57, 163,93mg/g under 15, 25 and 35°C after modification, respectively. Thermodynamic parameters show that the adsorption of phenol on activated carbon is a spontaneously exothermic process of entropy reduction, implying that the adsorption is a physical adsorption. The adsorption of phenol on activated carbon follows the pseudo-second-order kinetics (R2>0.99. The optimum pH of adsorption is 6~8.

  20. Mechanisms affecting emission in rare-earth-activated phosphors

    Energy Technology Data Exchange (ETDEWEB)

    TALLANT,DAVID R.; SEAGER,CARLETON H.; SIMPSON,REGINA L.

    2000-05-23

    The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. The authors research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low-energy electron beams are used to excite the emission.

  1. Microalloying of transition metal silicides by mechanical activation and field-activated reaction

    Energy Technology Data Exchange (ETDEWEB)

    Munir, Zuhair A. (Davis, CA); Woolman, Joseph N. (Davis, CA); Petrovic, John J. (Los Alamos, NM)

    2003-09-02

    Alloys of transition metal suicides that contain one or more alloying elements are fabricated by a two-stage process involving mechanical activation as the first stage and densification and field-activated reaction as the second stage. Mechanical activation, preferably performed by high-energy planetary milling, results in the incorporation of atoms of the alloying element(s) into the crystal lattice of the transition metal, while the densification and field-activated reaction, preferably performed by spark plasma sintering, result in the formation of the alloyed transition metal silicide. Among the many advantages of the process are its ability to accommodate materials that are incompatible in other alloying methods.

  2. A Review of Emerging Analytical Techniques for Objective Physical Activity Measurement in Humans.

    Science.gov (United States)

    Clark, Cain C T; Barnes, Claire M; Stratton, Gareth; McNarry, Melitta A; Mackintosh, Kelly A; Summers, Huw D

    2017-03-01

    Physical inactivity is one of the most prevalent risk factors for non-communicable diseases in the world. A fundamental barrier to enhancing physical activity levels and decreasing sedentary behavior is limited by our understanding of associated measurement and analytical techniques. The number of analytical techniques for physical activity measurement has grown significantly, and although emerging techniques may advance analyses, little consensus is presently available and further synthesis is therefore required. The objective of this review was to identify the accuracy of emerging analytical techniques used for physical activity measurement in humans. We conducted a search of electronic databases using Web of Science, PubMed, and Google Scholar. This review included studies written in English and published between January 2010 and December 2014 that assessed physical activity using emerging analytical techniques and reported technique accuracy. A total of 2064 papers were initially retrieved from three databases. After duplicates were removed and remaining articles screened, 50 full-text articles were reviewed, resulting in the inclusion of 11 articles that met the eligibility criteria. Despite the diverse nature and the range in accuracy associated with some of the analytic techniques, the rapid development of analytics has demonstrated that more sensitive information about physical activity may be attained. However, further refinement of these techniques is needed.

  3. Physical activity, stress reduction, and mood: insight into immunological mechanisms.

    Science.gov (United States)

    Hamer, Mark; Endrighi, Romano; Poole, Lydia

    2012-01-01

    Psychosocial factors, such as chronic mental stress and mood, are recognized as an important predictor of longevity and wellbeing. In particular, depression is independently associated with cardiovascular disease and all-cause mortality, and is often comorbid with chronic diseases that can worsen their associated health outcomes. Regular exercise is thought to be associated with stress reduction and better mood, which may partly mediate associations between depression, stress, and health outcomes. The underlying mechanisms for the positive effects of exercise on wellbeing remain poorly understood. In this overview we examine epidemiological evidence for an association between physical activity and mental health. We then describe the exercise withdrawal paradigm as an experimental protocol to study mechanisms linking exercise, mood, and stress. In particular we will discuss the potential role of the inflammatory response as a central mechanism.

  4. Cochlear power flux as an indicator of mechanical activity.

    Science.gov (United States)

    Diependaal, R J; de Boer, E; Viergever, M A

    1987-09-01

    The question of whether one can conclude just from basilar membrane (BM) vibration data that the cochlea is an active mechanical system is addressed. To this end, a method is developed which computes the power flux through a channel cross section of a short-wave cochlear model from a given BM vibration pattern. The power flux is an important indicator of mechanical activity because a rise in this function corresponds to creation of mechanical energy. The power flux method is applied to BM velocity patterns as measured by Johnstone and Yates [J. Acoust. Soc. Am. 55, 584-587 (1974)] and by Sellick et al. [Hear. Res. 10, 101-108 (1983)] in the guinea pig and by Robles et al. [Peripheral Auditory Mechanisms, edited by J.B. Allen, J.L. Hall, A.E. Hubbard, S.T. Neely, and A. Tubis (Springer, New York, 1986a), pp. 121-128, and J. Acoust. Soc. Am. 80, 1364-1374 (1986b)] in the chinchilla. Before the calculations are performed, the BM data are interpolated and smoothed in order to avoid numerical errors as a result of too few and noisy data points. The choice of the smoothing method influences the computed power flux function considerably. Nevertheless, the calculations appear to make a clear distinction between the "old" data, showing broad BM tuning (Johnstone and Yates, 1974), and the "new" data, in which the response is much more peaked (Sellick et al., 1983; Robles et al., 1986a, b). The former do not give rise to a significant increase of the power flux; the latter do, although less convincingly for the Sellick et al. (1983) data than for the Robles et al. (1986a,b) data. It is thus concluded that the recently obtained, sharply tuned BM responses reflect the presence of mechanical activity in the cochlea.

  5. Regulatory mechanisms of the phasic respiratory activity in cricothyroid muscle.

    Science.gov (United States)

    Dejonckere, P H; Lebacq, J

    1984-01-01

    Phasic respiratory activity of the cricothyroid muscle has been investigated with electromyography in 15 normal subjects, and in 19 pathological cases with well defined neurological troubles. It appears that phasic respiratory activity in the cricothyroid muscle, probably centrally generated, is under control of a complex and intricate mechanisms, in which the nervus laryngeus superior, the nervus laryngeus inferior, the vagus nerve and cross connections all together intervene. Furthermore, a peripheral modulation related somehow to the resistance of the airways is present. Despite differences between animal species, it seems that qualitatively the same contributing elements are present in animals and humans.

  6. Active Cellular Mechanics and Information Processing in the Living Cell

    Science.gov (United States)

    Rao, M.

    2014-07-01

    I will present our recent work on the organization of signaling molecules on the surface of living cells. Using novel experimental and theoretical approaches we have found that many cell surface receptors are organized as dynamic clusters driven by active currents and stresses generated by the cortical cytoskeleton adjoining the cell surface. We have shown that this organization is optimal for both information processing and computation. In connecting active mechanics in the cell with information processing and computation, we bring together two of the seminal works of Alan Turing.

  7. About mechanisms of tetonic activity of the satellites

    Science.gov (United States)

    Barkin, Yu. V.

    2003-04-01

    ABOUT MECHANISMS OF TECTONIC ACTIVITY OF THE SATELLITES Yu.V. Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Due to attraction of the central planet and others external bodies satellite is subjected by tidal and non-tidal deformations. Elastic energy is changed in dependence from mutual position and motion of celestial bodies and as result the tensional state of satellite and its tectonic (endogenous) activity also is changed. Satellites of the planets have the definite shell’s structure and due to own rotation these shells are characterized by different oblatenesses. Gravitational interaction of the satellite and its mother planet generates big additional mechanical forces (and moments) between the neighboring non-spherical shells of the satellite (mantle, core and crust). These forces and moments are cyclic functions of time, which are changed in the different time-scales. They generate corresponding cyclic perturbations of the tensional state of the shells, their deformations, small relative transnational displacements and slow rotation of the shells and others. In geological period of time it leads to a fundamental tectonic reconstruction of the body. Definite contribution to discussed phenomena are caused by classical tidal mechanism. of planet-satellite interaction. But in this report we discuss in first the new mechanisms of endogenous activity of celestial bodies. They are connected with differential gravitational attraction of non-spherical satellite shells by the external celestial bodies which leads: 1) to small relative rotation (nutations) of the shells; 2) to small relative translational motions of the shells (displacements of their center of mass); 3) to relative displacements and rotations of the shells due to eccentricity of their center of mass positions; 4) to viscous elastic deformations of the shells and oth. (Barkin, 2001). For higher evaluations of the power of satellite endogenous activities were obtained

  8. On the mechanism of biological activation by tritium.

    Science.gov (United States)

    Rozhko, T V; Badun, G A; Razzhivina, I A; Guseynov, O A; Guseynova, V E; Kudryasheva, N S

    2016-06-01

    The mechanism of biological activation by beta-emitting radionuclide tritium was studied. Luminous marine bacteria were used as a bioassay to monitor the biological effect of tritium with luminescence intensity as the physiological parameter tested. Two different types of tritium sources were used: HTO molecules distributed regularly in the surrounding aqueous medium, and a solid source with tritium atoms fixed on its surface (tritium-labeled films, 0.11, 0.28, 0.91, and 2.36 MBq/cm(2)). When using the tritium-labeled films, tritium penetration into the cells was prevented. The both types of tritium sources revealed similar changes in the bacterial luminescence kinetics: a delay period followed by bioluminescence activation. No monotonic dependences of bioluminescence activation efficiency on specific radioactivities of the films were found. A 15-day exposure to tritiated water (100 MBq/L) did not reveal mutations in bacterial DNA. The results obtained give preference to a "non-genomic" mechanism of bioluminescence activation by tritium. An activation of the intracellular bioluminescence process develops without penetration of tritium atoms into the cells and can be caused by intensification of trans-membrane cellular processes stimulated by ionization and radiolysis of aqueous media. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Effects of different pedalling techniques on muscle fatigue and mechanical efficiency during prolonged cycling.

    Science.gov (United States)

    Theurel, J; Crepin, M; Foissac, M; Temprado, J J

    2012-12-01

    The present study aimed to test the influence of the pedalling technique on the occurrence of muscular fatigue and on the energetic demand during prolonged constant-load cycling exercise. Subjects performed two prolonged (45 min) cycling sessions at constant intensity (75% of maximal aerobic power). In a random order, participants cycled either with their preferred technique (PT) during one session or were helped by a visual force-feedback to modify their pedalling pattern during the other one (FB). Index of pedalling effectiveness was significantly (Pcycling induced a significant reduction of maximal power output, which was greater after PT (-15 ± 9%) than after FB (-7 ± 12%). During steady-state FB, vastus lateralis muscle activity was significantly (Pexercise (FB: 19.0 ± 1.9% vs PT: 20.2 ± 1.9%). Although changes in muscular coordination pattern with feedback did not seem to influence GE, it could be mainly responsible for the reduction of muscle fatigue after prolonged cycling.

  10. The mechanical environment modulates intracellular calcium oscillation activities of myofibroblasts.

    Directory of Open Access Journals (Sweden)

    Charles Godbout

    Full Text Available Myofibroblast contraction is fundamental in the excessive tissue remodeling that is characteristic of fibrotic tissue contractures. Tissue remodeling during development of fibrosis leads to gradually increasing stiffness of the extracellular matrix. We propose that this increased stiffness positively feeds back on the contractile activities of myofibroblasts. We have previously shown that cycles of contraction directly correlate with periodic intracellular calcium oscillations in cultured myofibroblasts. We analyze cytosolic calcium dynamics using fluorescent calcium indicators to evaluate the possible impact of mechanical stress on myofibroblast contractile activity. To modulate extracellular mechanics, we seeded primary rat subcutaneous myofibroblasts on silicone substrates and into collagen gels of different elastic modulus. We modulated cell stress by cell growth on differently adhesive culture substrates, by restricting cell spreading area on micro-printed adhesive islands, and depolymerizing actin with Cytochalasin D. In general, calcium oscillation frequencies in myofibroblasts increased with increasing mechanical challenge. These results provide new insight on how changing mechanical conditions for myofibroblasts are encoded in calcium oscillations and possibly explain how reparative cells adapt their contractile behavior to the stresses occurring in normal and pathological tissue repair.

  11. Microglia mechanics: immune activation alters traction forces and durotaxis

    Science.gov (United States)

    Bollmann, Lars; Koser, David E.; Shahapure, Rajesh; Gautier, Hélène O. B.; Holzapfel, Gerhard A.; Scarcelli, Giuliano; Gather, Malte C.; Ulbricht, Elke; Franze, Kristian

    2015-01-01

    Microglial cells are key players in the primary immune response of the central nervous system. They are highly active and motile cells that chemically and mechanically interact with their environment. While the impact of chemical signaling on microglia function has been studied in much detail, the current understanding of mechanical signaling is very limited. When cultured on compliant substrates, primary microglial cells adapted their spread area, morphology, and actin cytoskeleton to the stiffness of their environment. Traction force microscopy revealed that forces exerted by microglia increase with substrate stiffness until reaching a plateau at a shear modulus of ~5 kPa. When cultured on substrates incorporating stiffness gradients, microglia preferentially migrated toward stiffer regions, a process termed durotaxis. Lipopolysaccharide-induced immune-activation of microglia led to changes in traction forces, increased migration velocities and an amplification of durotaxis. We finally developed a mathematical model connecting traction forces with the durotactic behavior of migrating microglial cells. Our results demonstrate that microglia are susceptible to mechanical signals, which could be important during central nervous system development and pathologies. Stiffness gradients in tissue surrounding neural implants such as electrodes, for example, could mechanically attract microglial cells, thus facilitating foreign body reactions detrimental to electrode functioning. PMID:26441534

  12. Mechanics of post-cam engagement during simulated dynamic activity.

    Science.gov (United States)

    Fitzpatrick, Clare K; Clary, Chadd W; Cyr, Adam J; Maletsky, Lorin P; Rullkoetter, Paul J

    2013-09-01

    Posterior-stabilized (PS) total knee arthroplasty (TKA) components employ a tibial post and femoral cam mechanism to guide anteroposterior knee motion in lieu of the posterior cruciate ligament. Some PS TKA patients report a clicking sensation when the post and cam engage, while severe wear and fracture of the post; we hypothesize that these complications are associated with excessive impact velocity at engagement. We evaluated the effect of implant design on engagement dynamics of the post-cam mechanism and resulting polyethylene stresses during dynamic activity. In vitro simulation of a knee bend activity was performed for four cadaveric specimens implanted with PS TKA components. Post-cam engagement velocity and flexion angle at initial contact were determined. The experimental data were used to validate computational predictions of PS mechanics using the same loading conditions. A lower limb model was subsequently utilized to compare engagement mechanics of eight TKA designs, relating differences between implants to geometric design features. Flexion angle and post-cam velocity at engagement demonstrated considerable ranges among designs (23°-89°, and 0.05-0.22 mm/°, respectively). Post-cam velocity was correlated (r = 0.89) with tibiofemoral condylar design features. Condylar geometry, in addition to post-cam geometry, played a significant role in minimizing engagement velocity and forces and stresses in the post. This analysis guides selection and design of PS implants that facilitate smooth post-cam engagement and reduce edge loading of the post.

  13. Unraveling the Photocatalytic Mechanisms on TiO2 Surfaces Using the Oxygen-18 Isotopic Label Technique

    Directory of Open Access Journals (Sweden)

    Xibin Pang

    2014-10-01

    Full Text Available During the last several decades TiO2 photocatalytic oxidation using the molecular oxygen in air has emerged as a promising method for the degradation of recalcitrant organic pollutants and selective transformations of valuable organic chemicals. Despite extensive studies, the mechanisms of these photocatalytic reactions are still poorly understood due to their complexity. In this review, we will highlight how the oxygen-18 isotope labeling technique can be a powerful tool to elucidate complicated photocatalytic mechanisms taking place on the TiO2 surface. To this end, the application of the oxygen-18 isotopic-labeling method to three representative photocatalytic reactions is discussed: (1 the photocatalytic hydroxylation of aromatics; (2 oxidative cleavage of aryl rings on the TiO2 surface; and (3 photocatalytic decarboxylation of saturated carboxylic acids. The results show that the oxygen atoms of molecular oxygen can incorporate into the corresponding products in aqueous solution in all three of these reactions, but the detailed incorporation pathways are completely different in each case. For the hydroxylation process, the O atom in O2 is shown to be incorporated through activation of O2 by conduction band electrons. In the cleavage of aryl rings, O atoms are inserted into the aryl ring through the site-dependent coordination of reactants on the TiO2 surface. A new pathway for the decarboxylation of saturated carboxylic acids with pyruvic acid as an intermediate is identified, and the O2 is incorporated into the products through the further oxidation of pyruvic acid by active species from the activation of O2 by conduction band electrons.

  14. Microstructures and Mechanical Properties of Co-Cr Dental Alloys Fabricated by Three CAD/CAM-Based Processing Techniques

    Directory of Open Access Journals (Sweden)

    Hae Ri Kim

    2016-07-01

    Full Text Available The microstructures and mechanical properties of cobalt-chromium (Co-Cr alloys produced by three CAD/CAM-based processing techniques were investigated in comparison with those produced by the traditional casting technique. Four groups of disc- (microstructures or dumbbell- (mechanical properties specimens made of Co-Cr alloys were prepared using casting (CS, milling (ML, selective laser melting (SLM, and milling/post-sintering (ML/PS. For each technique, the corresponding commercial alloy material was used. The microstructures of the specimens were evaluated via X-ray diffractometry, optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy, and electron backscattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test according to ISO 22674 (n = 6. The microstructure of the alloys was strongly influenced by the manufacturing processes. Overall, the SLM group showed superior mechanical properties, the ML/PS group being nearly comparable. The mechanical properties of the ML group were inferior to those of the CS group. The microstructures and mechanical properties of Co-Cr alloys were greatly dependent on the manufacturing technique as well as the chemical composition. The SLM and ML/PS techniques may be considered promising alternatives to the Co-Cr alloy casting process.

  15. Effects of nanosuspension and inclusion complex techniques on the in vitro protease inhibitory activity of naproxen

    OpenAIRE

    Dharmalingam, Senthil Rajan; Chidambaram, Kumarappan; Ramamurthy, Srinivasan; Nadaraju,Shamala

    2014-01-01

    This study investigated the effects of nanosuspension and inclusion complex techniques on in vitro trypsin inhibitory activity of naproxen—a member of the propionic acid derivatives, which are a group of antipyretic, analgesic, and non-steroidal anti-inflammatory drugs. Nanosuspension and inclusion complex techniques were used to increase the solubility and anti-inflammatory efficacy of naproxen. The evaporative precipitation into aqueous solution (EPAS) technique and the kneading metho...

  16. Allosteric activation mechanism of the cys-loop receptors

    Institute of Scientific and Technical Information of China (English)

    Yong-chang CHANG; Wen WU; Jian-liang ZHANG; Yao HUANG

    2009-01-01

    Binding of a neurotransmitter to its ionotropic receptor opens a distantly located ion channel, a process termed allosteric activation. Here we review recent advances in the molecular mechanism by which the cys-loop receptors are activated with emphasis on the best studied nicotinic acetylcholine receptors (nAChRs). With a combination of affinity labeling, mutagenesis, electrophysiology, kinetic modeling, electron microscopy (EM), and crystal structure analysis, the allosteric activation mechanism is emerging. Specifically, the binding domain and gating domain are interconnected by an allosteric activation network. Agonist binding induces conformational changes, resulting in the rotation of a β sheet of amino-terminal domain and outward movement of loop 2, loop F, and cys-loop, which are coupled to the M2-M3 linker to pull the channel to open. However, there are still some controversies about the movement of the channel-lining domain M2. Nine angstrom resolution EM structure of a nAChR imaged in the open state suggests that channel opening is the result of rotation of the M2 domain. In contrast, recent crystal structures of bacterial homologues of the cys-loop receptor family in apparently open state have implied an M2 tilting model with pore dilation and quaternary twist of the whole pentameric receptor. An elegant study of the nAChR using protonation scanning of M2 domain supports a similar pore dilation activation mechanism with minimal rotation of M2. This remains to be validated with other approaches including high resolution structure determination of the mammalian cys-loop receptors in the open state.

  17. Development of active control technique for engine noise. Engine soon no active seigyo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, H.; Nakao, N.; Butsuen, T. (Mazda Motor Corp., Hiroshima (Japan))

    1994-03-31

    As a measure to reduce engine noise in a car, the active noise control (ANC) technique to eliminate noise by another noise of antiphase has been studied. The conventional filtered-x LMS control algorithm has been generally applied to the ANC, but a large quantity of arithmetic operation used for filtering is practically problematic. This paper proposes the new algorithm of which control effects and practicability have been improved by utilizing periodicity of engine noise and by introducing the idea of error scanning. This algorithm requires only 30-50% of the arithmetic operation of the above LMS method. Concerning the actual system structure, arrangement and the number of microphones have been examined based on the detailed measurement results of the spatial distribution of noise in a car. As a result, the suitable arrangement of only three microphones to reduce noise in the whole interior space of a car is found. Through the experiments, maximum noise reduction of 8dB (A scale) has been achieved at each seat position. 7 refs., 9 figs., 1 tab.

  18. COMPARISON OF ACTIVE RELEASE TECHNIQUE AND MYOFASCIAL RELEASE TECHNIQUE ON PAIN, GRIP STRENGTH & FUNCTIONAL PERFORMANCE IN PATIENTS WITH CHRONIC LATERAL EPICONDYLITIS

    Directory of Open Access Journals (Sweden)

    Parth Trivedi

    2014-06-01

    Full Text Available Background & Purpose: Lateral epicondylitis is the most common lesion of the elbow. Tennis elbow or lateral epicondylitis is defined as a syndrome of pain in the wrist extensor muscles at or near their lateral epicondyle origin or pain directly over the lateral epicondyle. So, the aim of this study was to compare the effectiveness of Active Release Technique (ART and Myofascial Release Technique (MFR in the treatment of Chronic Lateral Epicondylitis (CLE. Methodology: The study included thirty-six patients with Chronic Lateral Epicondylitis of age group range between 30 to 45 years. Patients were randomly divided into three groups: Control Group (A, Active Release Technique Group (B and Myofascial Release Technique Group (C. The patients were treated for 4 weeks and three outcome measures: 0-10 NPRS, Hand Dynamometer and PRTEE were taken for assessment and analysis at baseline and after 4th weeks was done. Result: In this study the result showed that Active Release Technique and Myofascial Release Technique were effective in all three outcome measures when compared to Control Group. Myofascial Release Technique was more effective in improving grip strength & reducing pain & disability when compared to Active Release Technique.(p<0.05 Conclusion: Active Release Technique and Myofascial Release Technique are effective in patients with Chronic Lateral Epicondylitis. Myofascial Release Technique demonstrated better outcomes than Active Release Technique in the management of Chronic Lateral Epicondylitis.

  19. Comparison of Active and Passive Humidifiers on Mechanical Ventilation

    Directory of Open Access Journals (Sweden)

    H. Dilek Mersin Özcanoğlu

    2010-12-01

    Full Text Available Objective: To research the effectiveness on humidifying, respiratory mechanics, bacterial colonization and infection rates of continuous usage for 96 hours of active and passive humidifiers which are used for heating and moisturizing the inspired gases in patients under mechanical ventilation. Materials and Methods: Adult patients who are expected to support at least 4 days under mechanical ventilation, excluding patients with primary lung disease and sepsis, are included in the research. Patients are separated in two groups as a passive humidifier group (heat moisture exchange filter (n=16 and an active humidifier group (n=14. In passive humidifier group, humidifier is used continuously for 96 hours without change. In active humidifier group moisturizing is obtained by using sterile distilled water in heated humidifier. Patients whose demographic characteristics were recorded and first 24 hour APACHE II scores were calculated, were taking chest X-Ray’s daily. Respiratory mechanics measurements were recorded twice a day which were watched in Servo300A ventilators respiratory mechanics monitor, in patients under volume controlled ventilation. The amount of moisture and liquidity of the secretion in endotracheal tube were recorded and scored visually. The endotracheal aspiration samples at the beginning and at the end of 96th hour and respiratory circuits ventilator side sample taken at 96th hour were studied microbiologically. Cultures and colonial counts were studied at Cerrahpasa Medical Faculty Microbiology Laboratory. Results: There were no significant difference in two groups by demographic data, APACHE II scores and illness diagnoses. In passive humidifier group, respiratory mechanics showed no significant difference between the beginning and the 4th day (p>0.05. In active humidifier group when MAP, PEEPtot, EEF, Rins, Rexp values showed no significant difference between the beginning and the 4th day but PIP values showed significant

  20. ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n—HEXANE ON ACTIVATED CARBONS BY PTD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    LIZhong; WANGHongjuan; 等

    2001-01-01

    In this paper,six kinds of activated carbons such as Ag+-activated carbon,Cu2+activated carbon,Fe3+-activated carbon,activated carbon,Ba2+-activated carbon and Ca2+activated carbon were prepared.The model for estimating activated energy of desorption was established.Temperature-programmed desorption(TPD)experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons.Results showed that the activation energy for the desorption of n-hexanol on the Ag+-activated carbon,the Cu2+-activated carbon and the Fe3+-activated carbon were higher than those of n-hexanol on the activated carbon,the Ca2+-activated carbon and the Ba2+-activated carbon.

  1. ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, six kinds of activated carbons such as Ag+-activated carbon, Cu2+-activated carbon, Fe3+- activated carbon, activated carbon, Ba2+- activated carbon and Ca2+-activated carbon were prepared. The model for estimating activated energy of desorption was established. Temperature-programmed desorption (TPD) experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons. Results showed that the activation energy for the desorption of n-hexanol on the Ag+- activated carbon, the Cu2+- activated carbon and the Fe3+- activated carbon were higher than those of n-hexanol on the activated carbon, the Ca2+- activated carbon and the Ba2+- activated carbon.

  2. On the respiratory mechanics measured by forced oscillation technique in patients with systemic sclerosis.

    Directory of Open Access Journals (Sweden)

    Ingrid Almeida Miranda

    Full Text Available BACKGROUND: Pulmonary complications are the most common cause of death and morbidity in systemic sclerosis (SSc. The forced oscillation technique (FOT offers a simple and detailed approach to investigate the mechanical properties of the respiratory system. We hypothesized that SSc may introduce changes in the resistive and reactive properties of the respiratory system, and that FOT may help the diagnosis of these abnormalities. METHODOLOGY/PRINCIPAL FINDINGS: We tested these hypotheses in controls (n = 30 and patients with abnormalities classified using spirometry (n = 52 and pulmonary volumes (n = 29. Resistive data were interpreted with the zero-intercept resistance (Ri and the slope of the resistance (S as a function of frequency. Reactance changes were evaluated by the mean reactance between 4 and 32 Hz (Xm and the dynamic compliance (Crs,dyn. The mechanical load was evaluated using the absolute value of the impedance in 4 Hz (Z4Hz. A compartmental model was used to obtain central (R and peripheral (Rp resistances, and alveolar compliance (C. The clinical usefulness was evaluated by investigating the area under the receiver operating characteristic curve (AUC. The presence of expiratory flow limitation (EFL was also evaluated. For the groups classified using spirometry, SSc resulted in increased values in Ri, R, Rp and Z4Hz (p0.90. In groups classified by pulmonary volume, SSc resulted in reductions in S, Xm, C and Crs,dyn (p0.80. It was also observed that EFL is not common in patients with SSc. CONCLUSIONS/SIGNIFICANCE: This study provides evidence that the respiratory resistance and reactance are changed in SSc. This analysis provides a useful description that is of particular significance for understanding respiratory pathophysiology and to ease the diagnosis of respiratory abnormalities in these patients.

  3. Exploring Undergraduates' Perceptions of the Use of Active Learning Techniques in Science Lectures

    Science.gov (United States)

    Welsh, Ashley J.

    2012-01-01

    This paper examines students' mixed perceptions of the use of active learning techniques in undergraduate science lectures. Written comments from over 250 students offered an in-depth view of why students perceive these techniques as helping or hindering their learning and experience. Fourth- and fifth-year students were more likely to view…

  4. Chronic musculoskeletal pain: review of mechanisms and biochemical biomarkers as assessed by the microdialysis technique

    Directory of Open Access Journals (Sweden)

    Gerdle B

    2014-06-01

    Full Text Available Björn Gerdle,1,2 Bijar Ghafouri,1,3 Malin Ernberg,4 Britt Larsson1,21Rehabilitation Medicine, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; 2Pain and Rehabilitation Centre, County Council of Östergötland, Linköping, Sweden; 3Rehabilitation Medicine, Department of Medicine and Health Sciences, Linköping University, Linköping, Sweden; 4Department of Dental Medicine, Section of Orofacial Pain and Jaw Function, Karolinska Institutet, Huddinge, SwedenAbstract: Chronic musculoskeletal pain conditions are multifaceted, and approximately 20% of the adult population lives with severe chronic pain, with a higher prevalence in women and in lower income groups. Chronic pain is influenced by and interacts with physical, emotional, psychological, and social factors, and a biopsychosocial framework is increasingly applied in clinical practice. However, there is still a lack of assessment procedures based on the activated neurobiological pain mechanisms (ie, the biological part of the biopsychosocial model of pain, which may be a necessary step for further optimizing outcomes after treatments for patients with chronic pain. It has been suggested that chronic pain conditions are mainly driven by alterations in the central nervous system with little or no peripheral stimuli or nociception. In contrast, other authors argue that such central alterations are driven by peripheral alterations and nociceptive input. Microdialysis is an in vivo method for studying local tissue alterations and allows for sampling of substances in the interstitium of the muscle, where nociceptor free nerve endings are found close to the muscle fibers. The extracellular matrix plays a key role in physiologic functions of cells, including the primary afferent nociceptor. The present review mainly concerns the results of microdialysis studies and how they can contribute to the understanding of activated peripheral nociceptive and pain

  5. Complementary medicine for the management of chronic stress: superiority of active versus passive techniques.

    Science.gov (United States)

    Lucini, Daniela; Malacarne, Mara; Solaro, Nadia; Busin, Silvano; Pagani, Massimo

    2009-12-01

    Recent epidemiological data indicate that chronic stress is an important component of cardiovascular risk, implicitly suggesting that stress management might offer a useful complement to orthodox medical treatment and prevention of hypertension. In this context, information on mechanisms, such as subclinical increases in arterial pressure and sympathetic drive, is well documented. Conversely, evidence on methodologies and comparative efficacy needs to be improved. Accordingly, this study was planned to test the autonomic and subjective effects of two popular modalities of stress management. We studied 70 patients complaining of stress-related symptoms, avoiding any potential autonomic confounder, such as established hypertension or drug treatment. Patients were divided in three groups: group I (n = 30) followed a breathing-guided relaxation training (active); group II (n = 15) an oriental massage, shiatsu (passive); and group III (n = 25) followed a sham intervention. Subjective effects of stress were assessed by validated questionnaires and autonomic nervous system regulation by spectral analysis of RR interval variability. Factor analysis was used to extract information simultaneously embedded in subjective and functional data. Although the problem of a greater quantity of treatment procedure in the active group than in the passive group existed, results showed that active relaxation, further to slightly reducing arterial pressure, might be more effective in relieving symptoms of stress and inducing an improved profile of autonomic cardiovascular regulation, as compared with passive massage or sham intervention. This active technique seems capable of beneficially addressing simultaneously the individual psychological and physiopathological dimensions of stress in clinical settings, with potentially beneficial effects on cardiovascular risk profile.

  6. Application of Imaging Techniques to Mechanics of Materials and Structures, Volume 4 : Proceedings of the 2010 Annual Conference on Experimental and Applied Mechanics

    CERN Document Server

    2013-01-01

    This the fourth volume of six from the Annual Conference of the Society for Experimental Mechanics, 2010, brings together 58 chapters on Application of Imaging Techniques to Mechanics of Materials and Structure. It presents findings from experimental and computational investigations involving a range of imaging techniques including Recovery of 3D Stress Intensity Factors From Surface Full-field Measurements, Identification of Cohesive-zone Laws From Crack-tip Deformation Fields, Application of High Speed Digital Image Correlation for Vibration Mode Shape Analysis, Characterization of Aluminum Alloys Using a 3D Full Field Measurement, and Low Strain Rate Measurements on Explosives Using DIC.

  7. Complement system part I - molecular mechanisms of activation and regulation

    Directory of Open Access Journals (Sweden)

    Nicolas eMerle

    2015-06-01

    Full Text Available Complement is a complex innate immune surveillance system, playing a key role in defense against pathogens and in host homeostasis. The complement system is initiated by conformational changes in recognition molecular complexes upon sensing danger signals. The subsequent cascade of enzymatic reactions is tightly regulated to assure that complement is activated only at specific locations requiring defense against pathogens, thus avoiding host tissue damage. Here we discuss the recent advances describing the molecular and structural basis of activation and regulation of the complement pathways and their implication on physiology and pathology. This article will review the mechanisms of activation of alternative, classical and lectin pathways, the formation of C3 and C5 convertases, the action of anaphylatoxins and the membrane attack complex. We will also discuss the importance of structure-function relationships using the example of atypical hemolytic uremic syndrome. Lastly we will discuss the development and benefits of therapies using complement inhibitors.

  8. Statistical Mechanics Ideas and Techniques Applied to Selected Problems in Ecology

    Directory of Open Access Journals (Sweden)

    Hugo Fort

    2013-11-01

    Full Text Available Ecosystem dynamics provides an interesting arena for the application of a plethora concepts and techniques from statistical mechanics. Here I review three examples corresponding each one to an important problem in ecology. First, I start with an analytical derivation of clumpy patterns for species relative abundances (SRA empirically observed in several ecological communities involving a high number n of species, a phenomenon which have puzzled ecologists for decades. An interesting point is that this derivation uses results obtained from a statistical mechanics model for ferromagnets. Second, going beyond the mean field approximation, I study the spatial version of a popular ecological model involving just one species representing vegetation. The goal is to address the phenomena of catastrophic shifts—gradual cumulative variations in some control parameter that suddenly lead to an abrupt change in the system—illustrating it by means of the process of desertification of arid lands. The focus is on the aggregation processes and the effects of diffusion that combined lead to the formation of non trivial spatial vegetation patterns. It is shown that different quantities—like the variance, the two-point correlation function and the patchiness—may serve as early warnings for the desertification of arid lands. Remarkably, in the onset of a desertification transition the distribution of vegetation patches exhibits scale invariance typical of many physical systems in the vicinity a phase transition. I comment on similarities of and differences between these catastrophic shifts and paradigmatic thermodynamic phase transitions like the liquid-vapor change of state for a fluid. Third, I analyze the case of many species interacting in space. I choose tropical forests, which are mega-diverse ecosystems that exhibit remarkable dynamics. Therefore these ecosystems represent a research paradigm both for studies of complex systems dynamics as well as to

  9. Common Practice Lightning Strike Protection Characterization Technique to Quantify Damage Mechanisms on Composite Substrates

    Science.gov (United States)

    Szatkowski, George N.; Dudley, Kenneth L.; Koppen, Sandra V.; Ely, Jay J.; Nguyen, Truong X.; Ticatch, Larry A.; Mielnik, John J.; Mcneill, Patrick A.

    2013-01-01

    heating parameters which occur during lightning attachment. Following guidance defined in the universal common practice LSP test documents, protected and unprotected CFRP panels were evaluated at 20, 40 and 100KAmps. This report presents analyzed data demonstrating the scientific usefulness of the common practice approach. Descriptions of the common practice CFRP test articles, LSP test bed fixture, and monitoring techniques to capture the electrical, mechanical and thermal parameters during lightning attachment are presented here. Two methods of measuring the electrical currents were evaluated, inductive current probes and a newly developed fiberoptic sensor. Two mechanical displacement methods were also examined, optical laser measurement sensors and a digital imaging correlation camera system. Recommendations are provided to help users implement the common practice test approach and obtain LSP test characterizations comparable across data sets.

  10. Bond-slip detection of concrete-encased composite structure using electro-mechanical impedance technique

    Science.gov (United States)

    Liang, Yabin; Li, Dongsheng; Parvasi, Seyed Mohammad; Kong, Qingzhao; Lim, Ing; Song, Gangbing

    2016-09-01

    Concrete-encased composite structure is a type of structure that takes the advantages of both steel and concrete materials, showing improved strength, ductility, and fire resistance compared to traditional reinforced concrete structures. The interface between concrete and steel profiles governs the interaction between these two materials under loading, however, debonding damage between these two materials may lead to severe degradation of the load transferring capacity which will affect the structural performance significantly. In this paper, the electro-mechanical impedance (EMI) technique using piezoceramic transducers was experimentally investigated to detect the bond-slip occurrence of the concrete-encased composite structure. The root-mean-square deviation is used to quantify the variations of the impedance signatures due to the presence of the bond-slip damage. In order to verify the validity of the proposed method, finite element model analysis was performed to simulate the behavior of concrete-steel debonding based on a 3D finite element concrete-steel bond model. The computed impedance signatures from the numerical results are compared with the results obtained from the experimental study, and both the numerical and experimental studies verify the proposed EMI method to detect bond slip of a concrete-encased composite structure.

  11. Characterization of Shape Memory Polymer Estane by Means of Dynamic Mechanical Thermal Analysis Technique

    Directory of Open Access Journals (Sweden)

    Rasa Kazakevičiūtė-Makovska

    2014-01-01

    Full Text Available Commercially available shape memory polymer (SMP Estane (designation: ETE75DT3 NAT022 is investigated by means of dynamic mechanical thermal analysis (DMTA technique in torsion mode using the Modular Compact Rheometer MCR-301 (Anton Paar GmbH. Amplitude sweep tests have been run below and above the glass transition temperature to establish the linear viscoelastic range (LVR in glassy and rubbery phase of this SMP for the correct physical interpretation of DMTA data. Temperature sweep tests were performed at various frequencies to study the influence of this parameter on values of the storage and loss moduli and the storage and loss compliances as well as the viscosities. These tests have been carried out in heating mode with different rates and at different strain amplitudes. The short- and long-term behavior of SMP Estane have been studied by frequency sweep tests performed at different temperatures and data have been transformed into time-domain properties by applying time-temperature superposition principles. All these DMTA data provide the experimental basis for the study of relaxation processes, property-structure relationships, and the shape memory effect in this little-known SMP.

  12. Mechanical characterization of hyperelastic materials with fringe projection and optimization techniques

    Science.gov (United States)

    Genovese, Katia; Lamberti, Luciano; Pappalettere, Carmine

    2006-05-01

    This paper presents a new hybrid technique for mechanical characterization of hyperelastic materials. The research is motivated by the fact that standard identification procedures based on the fitting of strain-stress curves determined experimentally from planar biaxial tests may be inaccurate for non-uniform states of deformation. Therefore, we propose an alternative approach where the difference Ω between the displacement field measured with Projection Moiré and its counterpart predicted by FEM is minimized using non-linear optimization algorithms that finally find unknown material properties. In order to check the feasibility of the new procedure, we considered a thin latex membrane modelling it as a two-parameter Mooney-Rivlin (MR) hyperelastic material. The Ω function is minimized either using optimization routines available in a commercial finite element package and by implementing a global optimizer able to deal with non-linearity and non-convexity included in the identification process. In order to check accuracy of optimization results, target values of MR constants for the latex specimen tested have previously been determined by fitting experimental stress-strain data gathered from a standard planar biaxial tension test. Results indicate that the present hybrid identification procedure can determine accurately properties of the hyperelastic material under investigation. In fact, the average residual error on displacements was less than 1% while the difference between the MR constants found with optimization and their target values was less than 3.5%.

  13. Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

    Indian Academy of Sciences (India)

    S C Sharma; N M Gokhale; Rajiv Dayal; Ramji Lal

    2002-02-01

    Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and microhardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO2. Flexural strength and fracture toughness were dependent on CeO2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce–ZrO2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness, 9.2 MPa √m.

  14. New techniques of the mechanical properties assessment for Advanced High Strength Steel (AHSS) in automobile

    Energy Technology Data Exchange (ETDEWEB)

    Fang Jian [Baoshan Iron and Steel Co., Ltd., Shanghai (China)

    2005-07-01

    Based on the mathematical polynomial and differentiate processing onto tensile stress-strain curve, the experimental technique to monitor the trace of working hardening exponent against strain was established, with the hope of linking the characterization of the mechanical properties to the insight into the microstructure behavior of AHSS. The features of a significant strain hardening peak with slow decaying followed was obtained existing on the n value trace of strain during uniform deformation, which may be the predominant contribution to the outstanding combination of strength and plasticity of AHSS. In comparison, for conventional high strength steel as quench and temper prepared, the form of n value trace was changed into the monotonous decreasing tendency within overall uniform extension. As regards the dynamic loading response of AHSS, the recorded impact force-displacement curve by instrumented impact testing with characteristic force points subdivided the absorbed impact energy into distinct components, corresponding to the crack initiation and propagation. Combined with the quasi static tensile, the concept of toughness parameters including J{sub d}, J-{delta}a and so-called ''local strain toughness, LST'' were proposed, which implies that the stable plastic deformation and pronounced energy consumption may lead to the excellent material response against cracking and rupture under various loading conditions. (orig.)

  15. New AFM Techniques for Investigating Molecular Growth Mechanisms of Protein Crystals

    Science.gov (United States)

    Li, Huayu; Nadarajah, Arunan; Konnert, John H.; Pusey, Marc L.

    1998-01-01

    Atomic Force Microscopy (AFM) has emerged as a powerful technique for investigating protein crystal growth. Earlier AFM studies were among the first to demonstrate that these crystals grew by dislocation and 2D nucleation growth mechanisms [1]. These investigations were restricted to the micron range where only surface features, such as dislocation hillocks and 2D islands are visible. Most AFM instruments can scan at higher resolutions and have the potential to resolve individual protein molecules at nanometer ranges. Such scans are essential for determining the molecular packing arrangements on crystal faces and for probing the growth process at the molecular level. However, at this resolution the AFM tip influences the image produced, with the resulting image being a convolution of the tip shape and the surface morphology [2]. In most studies this problem is resolved by deconvoluting the image to obtain the true surface morphology. Although deconvolution routines work reasonably well for simple one- dimensional shapes, for complex surfaces this approach does not produce accurate results. In this study we devised a new approach which takes advantage of the precise molecular order of crystal surfaces, combined with the knowledge of individual molecular shapes from the crystallographic data of the protein and the AFM tip shape. This information is used to construct expected theoretical AFM images by convoluting the tip shape with the constructed crystal surface shape for a given surface packing arrangement. By comparing the images from actual AFM scans with the constructed ones for different possible surface packing arrangements, the correct packing arrangement can be conclusively determined. This approach was used in this study to determine the correct one from two possible packing arrangements on (I 10) faces of tetragonal lysozyme crystals. Another novel AFM technique was also devised to measure the dimension of individual growth units of the crystal faces

  16. Mechanism of human natural killer cell activation by Haemophilus ducreyi.

    Science.gov (United States)

    Li, Wei; Janowicz, Diane M; Fortney, Kate R; Katz, Barry P; Spinola, Stanley M

    2009-08-15

    The role of natural killer (NK) cells in the host response to Haemophilus ducreyi infection is unclear. In pustules obtained from infected human volunteers, there was an enrichment of CD56bright NK cells bearing the activation markers CD69 and HLA-DR, compared with peripheral blood. To study the mechanism by which H. ducreyi activated NK cells, we used peripheral blood mononuclear cells from uninfected volunteers. H. ducreyi activated NK cells only in the presence of antigen-presenting cells. H. ducreyi-infected monocytes and monocyte-derived macrophages activated NK cells in a contact- and interleukin-18 (IL-18)-dependent manner, whereas monocyte-derived dendritic cells induced NK activation through soluble IL-12. More lesional NK cells than peripheral blood NK cells produced IFN-gamma in response to IL-12 and IL-18. We conclude that NK cells are recruited to experimental lesions and likely are activated by infected macrophages and dendritic cells. IFN-gamma produced by lesional NK cells may facilitate phagocytosis of H. ducreyi.

  17. Effect of substrate mechanical properties on T cell activation

    Science.gov (United States)

    Hui, King; Upadhyaya, Arpita

    2013-03-01

    T cell activation is a key process in cell-mediated immunity, and engagement of T cell receptors by peptides on antigen presenting cells leads to activation of signaling cascades as well as cytoskeletal reorganization and large scale membrane deformations. While significant advances have been made in understanding the biochemical signaling pathways, the effects imposed by the physical environment and the role of mechanical forces on cell activation are not well understood. In this study, we have used anti-CD3 coated elastic polyacrylamide gels as stimulatory substrates to enable the spreading of Jurkat T cells and the measurement of cellular traction forces. We have investigated the effect of substrate stiffness on the dynamics of T cell spreading and cellular force generation. We found that T cells display more active and sustained edge dynamics on softer gels and that they exert increased traction stresses with increasing gel stiffness. A dynamic actin cytoskeleton was required to maintain the forces generated during activation, as inferred from small molecule inhibition experiments. Our results indicate an important role for physical properties of the antigen presenting cell as well as cytoskeleton-driven forces in signaling activation.

  18. Microstructural and Mechanical Properties of Alkali Activated Colombian Raw Materials

    Directory of Open Access Journals (Sweden)

    Maria Criado

    2016-03-01

    Full Text Available Microstructural and mechanical properties of alkali activated binders based on blends of Colombian granulated blast furnace slag (GBFS and fly ash (FA were investigated. The synthesis of alkali activated binders was conducted at 85 °C for 24 h with different slag/fly ash ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100. Mineralogical and microstructural characterization was carried out by means of X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX and Nuclear magnetic resonance (NMR. Mechanical properties were evaluated through the compressive strength, modulus of elasticity and Poisson’s ratio. The results show that two different reaction products were detected in the slag/fly ash mixtures, a calcium silicate hydrate with Al in its structure (C-A-S-H gel and a sodium aluminosilicate hydrate (N-A-S-H gel with higher number of polymerized species and low content in Ca. It was found that with the increase of the amount of added slag, the amount of C-A-S-H gel increased and the amount of N-A-S-H gel decreased. The matrix was more dense and compact with almost absence of pores. The predominance of slag affected positively the compressive strength, Young’s modulus and Poisson’s ratio, with 80% slag and 20% fly ash concrete being the best mechanical performance blend.

  19. A novel technique for active vibration control, based on optimal tracking control

    Indian Academy of Sciences (India)

    BEHROUZ KHEIRI SARABI; MANU SHARMA; DAMANJEET KAUR

    2017-08-01

    In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a structure by simultaneously tracking zero references for modes of vibration. To illustrate the technique, a two-degrees of freedom spring-mass-dampersystem is considered as a test system. The mathematical model of the system is derived and then converted into a state-space model. A linear quadratic tracking control law is then used to make the disturbed system track zero references.

  20. A novel technique for active vibration control, based on optimal tracking control

    Science.gov (United States)

    Kheiri Sarabi, Behrouz; Sharma, Manu; Kaur, Damanjeet

    2017-08-01

    In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a structure by simultaneously tracking zero references for modes of vibration. To illustrate the technique, a two-degrees of freedom spring-mass-damper system is considered as a test system. The mathematical model of the system is derived and then converted into a state-space model. A linear quadratic tracking control law is then used to make the disturbed system track zero references.

  1. Hybrid magnetic mechanism for active locomotion based on inchworm motion

    Science.gov (United States)

    Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2013-02-01

    Magnetic robots have been studied in the past. Insect-type micro-robots are used in various biomedical applications; researchers have developed inchworm micro-robots for endoscopic use. A biological inchworm has a looping locomotion gait. However, most inchworm micro-robots depend on a general bending, or bellows, motion. In this paper, we introduce a new robotic mechanism using magnetic force and torque control in a rotating magnetic field for a looping gait. The proposed robot is controlled by the magnetic torque, attractive force, and body mechanisms (two stoppers, flexible body, and different frictional legs). The magnetic torque generates a general bending motion. In addition, the attractive force and body mechanisms produce the robot’s looping motion within a rotating magnetic field and without the use of an algorithm for field control. We verified the device’s performance and analyzed the motion through simulations and various experiments. The robot mechanism can be applied to active locomotion for various medical robots, such as wireless endoscopes.

  2. Complete reaction mechanisms of mercury oxidation on halogenated activated carbon.

    Science.gov (United States)

    Rungnim, Chompoonut; Promarak, Vinich; Hannongbua, Supa; Kungwan, Nawee; Namuangruk, Supawadee

    2016-06-05

    The reaction mechanisms of mercury (Hg) adsorption and oxidation on halogenated activated carbon (AC) have been completely studied for the first time using density functional theory (DFT) method. Two different halogenated AC models, namely X-AC and X-AC-X (X=Cl, Br, I), were adopted. The results revealed that HgX is found to be stable-state on the AC edge since its further desorption from the AC as HgX, or further oxidation to HgX2, are energetically unfavorable. Remarkably, the halide type does not significantly affect the Hg adsorption energy but it strongly affects the activation energy barrier of HgX formation, which obviously increases in the order HgIBr-AC>Cl-AC. Thus, the study of the complete reaction mechanism is essential because the adsorption energy can not be used as a guideline for the rational material design in the halide impregnated AC systems. The activation energy is an important descriptor for the predictions of sorbent reactivity to the Hg oxidation process.

  3. [Mechanism of arginine deiminase activity by site-directed mutagenesis].

    Science.gov (United States)

    Li, Lifeng; Ni, Ye; Sun, Zhihao

    2012-04-01

    Arginine deiminase (ADI) has been studied as a potential anti-cancer agent for inhibiting arginine-auxotrophic tumors (such as melanomas and hepatocellular carcinomas) in phase III clinical trials. In this work, we studied the molecular mechanism of arginine deiminase activity by site-directed mutagenesis. Three mutation sites, A128, H404 and 1410, were introduced into wild-type ADI gene by QuikChange site-directed mutagenesis method, and four ADI mutants M1 (A128T), M2 (H404R), M3 (I410L), and M4 (A128T, H404R) were obtained. The ADI mutants were individually expressed in Escherichia coli BL21 (DE3), and the enzymatic properties of the purified mutant proteins were determined. The results show that both A128T and H404R had enhanced optimum pH, higher activity and stability of ADI under physiological condition (pH 7.4), as well as reduced K(m) value. This study provides an insight into the molecular mechanism of the ADI activity, and also the experimental evidence for the rational protein evolution in the future.

  4. Whisker encoding of mechanical events during active tactile exploration

    Science.gov (United States)

    Boubenec, Yves; Shulz, Daniel E.; Debrégeas, Georges

    2012-01-01

    Rats use their whiskers to extract a wealth of information about their immediate environment, such as the shape, position or texture of an object. The information is conveyed to mechanoreceptors located within the whisker follicle in the form of a sequence of whisker deflections induced by the whisker/object contact interaction. How the whiskers filter and shape the mechanical information and effectively participate in the coding of tactile features remains an open question to date. In the present article, a biomechanical model was developed that provides predictions of the whisker dynamics during active tactile exploration, amenable to quantitative experimental comparison. This model is based on a decomposition of the whisker profile into a slow, quasi-static sequence and rapid resonant small-scale vibrations. It was applied to the typical situation of a rat actively whisking across a solid object. Having derived the quasi-static sequence of whisker deformation, the resonant properties of the whisker were analyzed, taking into account the boundary conditions imposed by the whisker/surface contact. We then focused on two elementary mechanical events that are expected to trigger significant neural responses, namely (1) the whisker/object first contact and (2) the whisker detachment from the object. Both events were found to trigger a deflection wave propagating upward to the mystacial pad at constant velocity of ≈3–5 m/s. This yielded a characteristic mechanical signature at the whisker base, in the form of a large peak of negative curvature occurring ≈4 ms after the event has been triggered. The dependence in amplitude and lag of this mechanical signal with the main contextual parameters (such as radial or angular distance) was investigated. The model was validated experimentally by comparing its predictions to high-speed video recordings of shock-induced whisker deflections performed on anesthetized rats. The consequences of these results on possible tactile

  5. Ontogenic timing mechanism initiates the expression of rat intestinal sucrase activity

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, K.Y.; Holt, P.R.

    1986-03-01

    Morphologic and enzymic differentiation occurs in rat small intestinal epithelium during 16-20 days of postnatal life. This change is considered to be initiated by an ontogenic timing mechanism and is modulated by extrinsic systemic and luminal factors. The importance of the ontogenic timing was tested directly using a transplantation technique in which jejunal isografts from newborn (day 0) and 5-day-old (day 5) rats were implanted under the skin of newborn (day 0) hosts. Isografts showing cryptvillus architecture were obtained in 44% and 21% of transplants, respectively. Day 0 isografts and host intestine expressed sucrase activity at about 16-18 days of age and showed similar crypt cell labeling and epithelial migration after (3H)thymidine injection. Day 5 isografts expressed sucrase activity when the hosts were 13 days of age, whereas host intestine showed no detectable sucrase activity. Isograft lactase activities in both experimental transplant models were significantly higher than host intestinal lactase up to 28 days of age, suggesting that luminal factors are important in modulating lactase activity during the first 4 wk of postnatal life. It is concluded that (a) no systemic factors at day 13 inhibit the expression of sucrase activity and (b) an ontogenic timing mechanism in the jejunum initiates the expression of sucrase activity.

  6. The activation mechanism of Fe-based olefin metathesis catalysts

    Science.gov (United States)

    Poater, Albert; Pump, Eva; Vummaleti, Sai Vikrama Chaitanya; Cavallo, Luigi

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts.

  7. Archaeal promoter architecture and mechanism of gene activation

    DEFF Research Database (Denmark)

    Peng, Nan; Ao, Xiang; Liang, Yun Xiang;

    2011-01-01

    Sulfolobus solfataricus and Sulfolobus islandicus contain several genes exhibiting D-arabinose-inducible expression and these systems are ideal for studying mechanisms of archaeal gene expression. At sequence level, only two highly conserved cis elements are present on the promoters: a regulatory...... element named ara box directing arabinose-inducible expression and the basal promoter element TATA, serving as the binding site for the TATA-binding protein. Strikingly, these promoters possess a modular structure that allows an essentially inactive basal promoter to be strongly activated. The invoked...

  8. Inspection of thin-walled pipe welds using mechanized ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lozev, M.; Spencer, R. [Edison Welding Inst., Columbus, OH (United States); Hodgkinson, D. [TransCanada PipeLines Ltd., Calgary, AB (Canada)

    2004-07-01

    This paper investigated applications of high-frequency single/multiprobe techniques and phased-array (PA) technology for the inspection of thin-walled pipes welds. Ultrasonic testing (UT), modeling and simulation was used as an effective way of determining that the desired calibration reflectors and flaws in thin-walled pipes can be accurately sized. A laboratory experiment was conducted in which simple or complex flaws were virtually split on several segments. Beam profile monitoring and automated ultrasonic testing was performed for non-focused 5, 10 and 15 MHz single elements, a variety of focused MHz elements, and a 10 MHz 32 element linear PA probe. A Mephisto model was used to examine the various echo-formation mechanisms. Beam interactions and connected planar flaws were examined. Two calibration targets were used: (1) a 1.5 mm diameter side-drilled hole; and (2) a 4 per cent deep notch. A thin-walled pipe sample was designed for the validation of modeling results. A commercially available PA system and computer software program was used to create focal laws, as well as to steer the beam, collect data, and perform the analysis. Results of the notch tilt models showed that inspection angles of approximately 58 to 68 degrees were the least sensitive to tilt. Signal amplitude losses of less than 10 decibels were observed when compared with the reference notch. The PA model for complex flaws showed that signal loss arising from tilt and skew stabilized at approximately 10 degrees due to a loss of amplitude. Larger sound beams resulted in a greater echo-dynamic that increased masking effects. It was concluded that the most accurate UT simulations were achieved using a 10 MHz, 32-element linear PA technology. 4 refs., 2 tabs., 8 figs.

  9. Efficacy of manual and mechanical instrumentation techniques for removal of overextended root canal filling material.

    Science.gov (United States)

    Kesim, B; Üstün, Y; Aslan, T; Topçuoğlu, H S; Şahin, S; Ulusan, Ö

    2017-06-01

    To compare the efficacy of manual and mechanical instrumentation techniques, including ProTaper Universal retreatment system, Mtwo retreatment system, Reciproc system, and Hedström files, regarding removal of overextended root canal filling material. Eighty extracted human mandibular premolar teeth were prepared at the apical foramen level using Revo-S rotary files and subsequently obturated. The root canal filling material was deliberately extruded from the apex. Samples were transferred to glass vials that simulated the periapical area. Eighty samples of overfilled teeth were randomly assigned to four equal groups (n = 20) for removal of the root filling material with ProTaper Universal retreatment files (Group 1), Mtwo retreatment files (Group 2), Reciproc system (Group 3), and hand files (Group 4). Removal of the root canal filling material and additional preparation were performed by individual instruments from each different system up to a #40 size. The external apical surface of the teeth and the surrounding glass vials were checked using a dental operation microscope with ×12.5 magnification. Samples were divided into two groups based on whether removal of the overextended root canal filling material was successful or not. The Fisher's exact test was used to detect any significant difference between the groups (α = 0.05). The success rate for removal of overextended gutta-percha was greater for the Mtwo (30%) and hand files (30%) compared with the ProTaper (20%) and Reciproc (10%). However, no significant statistical differences existed among the experimental groups (P > 0.05). This study demonstrated that all tested systems had similar efficacy in removing overextended root canal filling material.

  10. Mechanical investigation of U(VI) on pyrrhotite by batch, EXAFS and modeling techniques.

    Science.gov (United States)

    Liu, Haibo; Zhu, Yuke; Xu, Bin; Li, Ping; Sun, Yubing; Chen, Tianhu

    2017-01-15

    The interaction mechanism of U(VI) on pyrrhotite was demonstrated by batch, spectroscopic and modeling techniques. Pyrite was selected as control group in this study. The removal of U(VI) on pyrite and pyrrhotite significantly decreased with increasing ionic strength from 0.001 to 0.1mol/L at pH 2.0-6.0, whereas the no effect of ionic strength was observed at pH >6.0. The maximum removal capacity of U(VI) on pyrite and pyrrhotite calculated from Langmuir model was 10.20 and 21.34mgg(-1) at pH 4.0 and 333K, respectively. The XPS analysis indicated the U(VI) was primarily adsorbed on pyrrhotite and pyrite and then approximately 15.5 and 9.8% of U(VI) were reduced to U(IV) by pyrrhotite and pyrite after 20 days, respectively. Based on the XANES analysis, the adsorption edge of uranium-containing pyrrhotite located between U(IV)O2(s) and U(VI)O2(2+) spectra. The EXAFS analysis demonstrated the inner-sphere surface complexation of U(VI) on pyrrhotite due to the occurrence of U-S shell, whereas the U-U shell revealed the reductive co-precipitates of U(VI) on pyrrhotite/pyrite with increasing reaction times. The surface complexation modeling showed that outer- and inner-surface complexation dominated the U(VI) removal at pH5.0, respectively. The findings presented herein play a crucial role in the removal of radionuclides on iron sulfide in environmental cleanup applications.

  11. Common folds and transport mechanisms of secondary active transporters.

    Science.gov (United States)

    Shi, Yigong

    2013-01-01

    Secondary active transporters exploit the electrochemical potential of solutes to shuttle specific substrate molecules across biological membranes, usually against their concentration gradient. Transporters of different functional families with little sequence similarity have repeatedly been found to exhibit similar folds, exemplified by the MFS, LeuT, and NhaA folds. Observations of multiple conformational states of the same transporter, represented by the LeuT superfamily members Mhp1, AdiC, vSGLT, and LeuT, led to proposals that structural changes are associated with substrate binding and transport. Despite recent biochemical and structural advances, our understanding of substrate recognition and energy coupling is rather preliminary. This review focuses on the common folds and shared transport mechanisms of secondary active transporters. Available structural information generally supports the alternating access model for substrate transport, with variations and extensions made by emerging structural, biochemical, and computational evidence.

  12. ACTIVATION-ENERGY SPECTRA FOR STRESS-INDUCED ORDERING IN AMORPHOUS MATERIALS CALCULATED USING FOURIER TECHNIQUES

    NARCIS (Netherlands)

    KASARDOVA, A; Ocelik, Vaclav; CSACH, K; MISKUF, J

    A method for calculating the activation energy spectrum from isothermal data using Fourier techniques is used for studying the deformation processes in amorphous metals. The influence of experimental error on the calculated spectrum is discussed. The activation energy spectrum derived from the

  13. Reconstructing muscle activation during normal walking: a comparison of symbolic and connectionist machine learning techniques

    NARCIS (Netherlands)

    Heller, Ben W.; Veltink, Peter H.; Rijkhoff, Nico J.M.; Rutten, Wim L.C.; Andrews, Brian J.

    1993-01-01

    One symbolic (rule-based inductive learning) and one connectionist (neural network) machine learning technique were used to reconstruct muscle activation patterns from kinematic data measured during normal human walking at several speeds. The activation patterns (or desired outputs) consisted of sur

  14. Reconstructing muscle activation during normal walking: a comparison of symbolic and connectionist machine learning techniques

    NARCIS (Netherlands)

    Heller, Ben W.; Veltink, Petrus H.; Rijkhoff, N.J.M.; Rijkhoff, Nico J.M.; Rutten, Wim; Andrews, Brian J.

    1993-01-01

    One symbolic (rule-based inductive learning) and one connectionist (neural network) machine learning technique were used to reconstruct muscle activation patterns from kinematic data measured during normal human walking at several speeds. The activation patterns (or desired outputs) consisted of

  15. Applying Modern Techniques and Carrying Out English .Extracurricular—— On the Model United Nations Activity

    Institute of Scientific and Technical Information of China (English)

    XuXiaoyu; WangJian

    2004-01-01

    This paper is an introduction of the extracurricular activity of the Model United Nations in Northwestern Polyteehnical University (NPU) and it focuses on the application of the modem techniques in the activity and the pedagogical theories applied in it. An interview and questionnaire research will reveal the influence of the Model United Nations.

  16. ACTIVATION-ENERGY SPECTRA FOR STRESS-INDUCED ORDERING IN AMORPHOUS MATERIALS CALCULATED USING FOURIER TECHNIQUES

    NARCIS (Netherlands)

    KASARDOVA, A; Ocelik, Vaclav; CSACH, K; MISKUF, J

    1995-01-01

    A method for calculating the activation energy spectrum from isothermal data using Fourier techniques is used for studying the deformation processes in amorphous metals. The influence of experimental error on the calculated spectrum is discussed. The activation energy spectrum derived from the anela

  17. Traveling through potential energy surfaces of disordered materials: the activation-relaxation technique

    NARCIS (Netherlands)

    Mousseau, N.; Barkema, G.T.

    A detailed description of the activation-relaxation technique (ART) is presented. This method defines events in the configurational energy landscape of disordered materials such as amorphous semiconductors, glasses and polymers, in a two-step process: first, a configuration is activated from a local

  18. A technique for detecting antifungal activity of proteins separated by polyacrylamide gel electrophoresis.

    Science.gov (United States)

    De Bolle, M F; Goderis, I J; Terras, F R; Cammue, B P; Broekaert, W F

    1991-06-01

    A technique was developed for the detection of antifungal activity of proteins after discontinuous polyacrylamide gel electrophoresis under native conditions. The antifungal activity is detected as growth inhibition zones in a homogeneous fungal lawn, grown in an agar layer spread on top of the polyacrylamide gel. The position of proteins with antifungal activity can be determined on a diffusion blot prepared from the same gel. The technique is illustrated for three antifungal plant proteins, i.e. alpha-purothionin, Urtica dioica agglutinin, and tobacco chitinase.

  19. Deciphering Molecular Mechanism Underlying Hypolipidemic Activity of Echinocystic Acid

    Directory of Open Access Journals (Sweden)

    Li Han

    2014-01-01

    Full Text Available Our previous study showed that a triterpene mixture, consisting of echinocystic acid (EA and oleanolic acid (OA at a ratio of 4 : 1, dose-dependently ameliorated the hyperlipidemia and atherosclerosis in rabbits fed with high fat/high cholesterol diets. This study was aimed at exploring the mechanisms underlying antihyperlipidemic effect of EA. Molecular docking simulation of EA was performed using Molegro Virtual Docker (version: 4.3.0 to investigate the potential targets related to lipid metabolism. Based on the molecular docking information, isotope labeling method or spectrophotometry was applied to examine the effect of EA on the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA reductase, acyl-CoA:cholesterol acyltransferase (ACAT, and diacylglycerol acyltransferase (DGAT in rat liver microsomes. Our results revealed a strong affinity of EA towards ACAT and DGAT in molecular docking analysis, while low binding affinity existed between EA and HMG-CoA reductase as well as between EA and cholesteryl ester transfer protein. Consistent with the results of molecular docking, in vitro enzyme activity assays showed that EA inhibited ACAT and DGAT, with IC50 values of 103 and 139 μM, respectively, and exhibited no significant effect on HMG-CoA reductase activity. The present findings suggest that EA may exert hypolipidemic effect by inhibiting the activity of ACAT and DGAT.

  20. Optimized energy landscape exploration using the ab initio based activation-relaxation technique

    Science.gov (United States)

    Machado-Charry, Eduardo; Béland, Laurent Karim; Caliste, Damien; Genovese, Luigi; Deutsch, Thierry; Mousseau, Normand; Pochet, Pascal

    2011-07-01

    Unbiased open-ended methods for finding transition states are powerful tools to understand diffusion and relaxation mechanisms associated with defect diffusion, growth processes, and catalysis. They have been little used, however, in conjunction with ab initio packages as these algorithms demanded large computational effort to generate even a single event. Here, we revisit the activation-relaxation technique (ART nouveau) and introduce a two-step convergence to the saddle point, combining the previously used Lanczós algorithm with the direct inversion in interactive subspace scheme. This combination makes it possible to generate events (from an initial minimum through a saddle point up to a final minimum) in a systematic fashion with a net 300-700 force evaluations per successful event. ART nouveau is coupled with BigDFT, a Kohn-Sham density functional theory (DFT) electronic structure code using a wavelet basis set with excellent efficiency on parallel computation, and applied to study the potential energy surface of C20 clusters, vacancy diffusion in bulk silicon, and reconstruction of the 4H-SiC surface.

  1. Optimized energy landscape exploration using the ab initio based activation-relaxation technique.

    Science.gov (United States)

    Machado-Charry, Eduardo; Béland, Laurent Karim; Caliste, Damien; Genovese, Luigi; Deutsch, Thierry; Mousseau, Normand; Pochet, Pascal

    2011-07-21

    Unbiased open-ended methods for finding transition states are powerful tools to understand diffusion and relaxation mechanisms associated with defect diffusion, growth processes, and catalysis. They have been little used, however, in conjunction with ab initio packages as these algorithms demanded large computational effort to generate even a single event. Here, we revisit the activation-relaxation technique (ART nouveau) and introduce a two-step convergence to the saddle point, combining the previously used Lanczós algorithm with the direct inversion in interactive subspace scheme. This combination makes it possible to generate events (from an initial minimum through a saddle point up to a final minimum) in a systematic fashion with a net 300-700 force evaluations per successful event. ART nouveau is coupled with BigDFT, a Kohn-Sham density functional theory (DFT) electronic structure code using a wavelet basis set with excellent efficiency on parallel computation, and applied to study the potential energy surface of C(20) clusters, vacancy diffusion in bulk silicon, and reconstruction of the 4H-SiC surface.

  2. Inferring brain-computational mechanisms with models of activity measurements.

    Science.gov (United States)

    Kriegeskorte, Nikolaus; Diedrichsen, Jörn

    2016-10-01

    High-resolution functional imaging is providing increasingly rich measurements of brain activity in animals and humans. A major challenge is to leverage such data to gain insight into the brain's computational mechanisms. The first step is to define candidate brain-computational models (BCMs) that can perform the behavioural task in question. We would then like to infer which of the candidate BCMs best accounts for measured brain-activity data. Here we describe a method that complements each BCM by a measurement model (MM), which simulates the way the brain-activity measurements reflect neuronal activity (e.g. local averaging in functional magnetic resonance imaging (fMRI) voxels or sparse sampling in array recordings). The resulting generative model (BCM-MM) produces simulated measurements. To avoid having to fit the MM to predict each individual measurement channel of the brain-activity data, we compare the measured and predicted data at the level of summary statistics. We describe a novel particular implementation of this approach, called probabilistic representational similarity analysis (pRSA) with MMs, which uses representational dissimilarity matrices (RDMs) as the summary statistics. We validate this method by simulations of fMRI measurements (locally averaging voxels) based on a deep convolutional neural network for visual object recognition. Results indicate that the way the measurements sample the activity patterns strongly affects the apparent representational dissimilarities. However, modelling of the measurement process can account for these effects, and different BCMs remain distinguishable even under substantial noise. The pRSA method enables us to perform Bayesian inference on the set of BCMs and to recognize the data-generating model in each case.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.

  3. Inferring brain-computational mechanisms with models of activity measurements

    Science.gov (United States)

    Diedrichsen, Jörn

    2016-01-01

    High-resolution functional imaging is providing increasingly rich measurements of brain activity in animals and humans. A major challenge is to leverage such data to gain insight into the brain's computational mechanisms. The first step is to define candidate brain-computational models (BCMs) that can perform the behavioural task in question. We would then like to infer which of the candidate BCMs best accounts for measured brain-activity data. Here we describe a method that complements each BCM by a measurement model (MM), which simulates the way the brain-activity measurements reflect neuronal activity (e.g. local averaging in functional magnetic resonance imaging (fMRI) voxels or sparse sampling in array recordings). The resulting generative model (BCM-MM) produces simulated measurements. To avoid having to fit the MM to predict each individual measurement channel of the brain-activity data, we compare the measured and predicted data at the level of summary statistics. We describe a novel particular implementation of this approach, called probabilistic representational similarity analysis (pRSA) with MMs, which uses representational dissimilarity matrices (RDMs) as the summary statistics. We validate this method by simulations of fMRI measurements (locally averaging voxels) based on a deep convolutional neural network for visual object recognition. Results indicate that the way the measurements sample the activity patterns strongly affects the apparent representational dissimilarities. However, modelling of the measurement process can account for these effects, and different BCMs remain distinguishable even under substantial noise. The pRSA method enables us to perform Bayesian inference on the set of BCMs and to recognize the data-generating model in each case. This article is part of the themed issue ‘Interpreting BOLD: a dialogue between cognitive and cellular neuroscience’. PMID:27574316

  4. MAG4 Versus Alternative Techniques for Forecasting Active-Region Flare Productivity

    Science.gov (United States)

    Falconer, David A.; Moore, Ronald L.; Barghouty, Abdulnasser F.; Khazanov, Igor

    2014-01-01

    MAG4 is a technique of forecasting an active region's rate of production of major flares in the coming few days from a free-magnetic-energy proxy. We present a statistical method of measuring the difference in performance between MAG4 and comparable alternative techniques that forecast an active region's major-flare productivity from alternative observed aspects of the active region. We demonstrate the method by measuring the difference in performance between the "Present MAG4" technique and each of three alternative techniques, called "McIntosh Active-Region Class," "Total Magnetic Flux," and "Next MAG4." We do this by using (1) the MAG4 database of magnetograms and major-flare histories of sunspot active regions, (2) the NOAA table of the major-flare productivity of each of 60 McIntosh active-region classes of sunspot active regions, and (3) five technique-performance metrics (Heidke Skill Score, True Skill Score, Percent Correct, Probability of Detection, and False Alarm Rate) evaluated from 2000 random two-by-two contingency tables obtained from the databases. We find that (1) Present MAG4 far outperforms both McIntosh Active-Region Class and Total Magnetic Flux, (2) Next MAG4 significantly outperforms Present MAG4, (3) the performance of Next MAG4 is insensitive to the forward and backward temporal windows used, in the range of one to a few days, and (4) forecasting from the free-energy proxy in combination with either any broad category of McIntosh active-region classes or any Mount Wilson active-region class gives no significant performance improvement over forecasting from the free-energy proxy alone (Present MAG4).

  5. Molecular mechanism by which AMP-activated protein kinase activation promotes glycogen accumulation in muscle

    DEFF Research Database (Denmark)

    Hunter, Roger W; Treebak, Jonas Thue; Wojtaszewski, Jørgen

    2011-01-01

    OBJECTIVE During energy stress, AMP-activated protein kinase (AMPK) promotes glucose transport and glycolysis for ATP production, while it is thought to inhibit anabolic glycogen synthesis by suppressing the activity of glycogen synthase (GS) to maintain the energy balance in muscle. Paradoxically......, chronic activation of AMPK causes an increase in glycogen accumulation in skeletal and cardiac muscles, which in some cases is associated with cardiac dysfunction. The aim of this study was to elucidate the molecular mechanism by which AMPK activation promotes muscle glycogen accumulation. RESEARCH DESIGN...... AND METHODS We recently generated knock-in mice in which wild-type muscle GS was replaced by a mutant (Arg582Ala) that could not be activated by glucose-6-phosphate (G6P), but possessed full catalytic activity and could still be activated normally by dephosphorylation. Muscles from GS knock-in or transgenic...

  6. Structure and Pozzolanic Activity of Calcined Coal Gangue during the Process of Mechanical Activation

    Institute of Scientific and Technical Information of China (English)

    GUO Wei; LI Dongxu; CHEN Jianhua; YANG Nanru

    2009-01-01

    On the basis of analyzing coal gangue's chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR,NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that, the lattice structure of metakaolin in coal gangue samples calcined at 700 ℃ disorganizes gradually and becomes disordered, and the lattice structure of α-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.

  7. Decoding the Interactions Regulating the Active State Mechanics of Eukaryotic Protein Kinases.

    Science.gov (United States)

    Meharena, Hiruy S; Fan, Xiaorui; Ahuja, Lalima G; Keshwani, Malik M; McClendon, Christopher L; Chen, Angela M; Adams, Joseph A; Taylor, Susan S

    2016-11-01

    Eukaryotic protein kinases regulate most cellular functions by phosphorylating targeted protein substrates through a highly conserved catalytic core. In the active state, the catalytic core oscillates between open, intermediate, and closed conformations. Currently, the intramolecular interactions that regulate the active state mechanics are not well understood. Here, using cAMP-dependent protein kinase as a representative model coupled with biochemical, biophysical, and computational techniques, we define a set of highly conserved electrostatic and hydrophobic interactions working harmoniously to regulate these mechanics. These include the previously identified salt bridge between a lysine from the β3-strand and a glutamate from the αC-helix as well as an electrostatic interaction between the phosphorylated activation loop and αC-helix and an ensemble of hydrophobic residues of the Regulatory spine and Shell. Moreover, for over three decades it was thought that the highly conserved β3-lysine was essential for phosphoryl transfer, but our findings show that the β3-lysine is not required for phosphoryl transfer but is essential for the active state mechanics.

  8. Whisker encoding of mechanical events during active tactile exploration

    Directory of Open Access Journals (Sweden)

    Yves eBoubenec

    2012-11-01

    Full Text Available Rats use their whiskers to extract a wealth of information about their immediate environment, such as the shape, position or texture of an object. The information is conveyed to mechanoreceptors located within the whisker follicle in the form of a sequence of whisker deflections induced by the whisker/object contact interaction. How the whiskers filter and shape the mechanical information and effectively participate in the coding of tactile features remains an open question to date. In the present article, a biomechanical model was developed that provides predictions of the whisker dynamics during active tactile exploration, amenable to quantitative experimental comparison. This model is based on a decomposition of the whisker profile into a slow, quasi-static sequence and rapid resonant small-scale vibrations. It was applied to the typical situation of a rat whisking across an object. Having derived the quasi-static sequence of whisker deformation, the resonant properties of the whisker were analyzed, taking into account the boundary conditions imposed by the whisker/surface contact. We then focused on two elementary mechanical events that are expected to trigger neural responses, namely (i the whisker/object first contact and (ii the whisker detachment from the object. Both events were found to trigger a deflection wave propagating upward to the mystacial pad at constant velocity of 3-5m/s. This yielded a characteristic mechanical signature at the whisker base, in the form of a large peak of negative curvature occurring 4ms after the event was triggered. The dependence in amplitude and lag of this mechanical signal with the main contextual parameters (such as radial or angular distance was investigated. The model was validated experimentally by comparing its predictions to high-speed video recordings of shock-induced whisker deflections performed on anesthetized rats. The consequences of these results on possible tactile encoding schemes are

  9. Usefulness of ultrasonic strain measurement-based mechanical properties imaging technique: toward realization of short time diagnosis/treatment

    Science.gov (United States)

    Sumi, Chikayoshi; Kubota, Mitsuhiro; Wakabayashi, Gou; Tanabe, Minoru

    2003-06-01

    For various soft tissues (e.g., liver, breast, etc.), we are developing the ultrasonic strain measurement-based mechanical properties (shear modulus, visco-shear modulus, etc.) reconstruction/imaging technique. To clarify the limitation of our quantitative reconstruction/imaging technique as a diagnostic tool for differentiating malignancies, together with improving the spatial resolution and the dynamic range we are collecting the clinical reconstruction image data. Furthermore, we are applying our technique as a monitoring technique for the effectiveness of chemical therapy (e.g., anticancer drug, ethanol, etc.), thermal therapy (e.g., micro, and rf electromagnetic wave, HIFU, LASER, etc.), and cryotherapy. As soft tissues are deformed in 3-D space due to externally situated quasi-static and/or low frequency mechanical sources, multidimensional signal processing improves strain measurement accuracy and reduces inhomogeneity-dependent modulus reconstruction artifacts. These have been verified by us through simulations and phantom/animal in vitro experiments. Briefly, here we discuss the limitations of low dimensional signal processing. Moreover, we exhibit the superiority both on differential diagnosis for these human in vivo malignancies and monitoring for these therapies of our quasi-real time imaging (using conventional US equipment) to conventional B-mode imaging. Our technique is available as a clinical visualization technique both for diagnosis and treatment, and monitored mechanical properties data can also be effectively utilized as the measure for controlling the therapy, i.e., the exposure energy, the foci, the exposure interval, etc. In the near future, suitable combination of various simple and low-invasive therapy techniques with our imaging technique will open up a new clinical style allowing diagnosis and the subsequently immediate treatment. This must substantially reduce the total medical expenses.

  10. Novel Fabrication Techniques for Wafer-Scale Graphene Drum NanoElectroMechanical Resonators

    Science.gov (United States)

    Lee, Sunwoo; Chen, Changyao; Deshpande, Vikram V.; Lee, Gwan Hyoung; Storch, Isaac; Zhang, Congchun; Yu, Young-Jun; Kim, Philip; McEuen, Paul; Hone, James

    2012-02-01

    Graphene NanoElectroMechanical Systems (NEMS) have shown excellent mass sensitivity as well as resonant and oscillatory behaviors that are desirable in mass sensors and active elements in Radio Frequency Integrated Circuit (RFIC) design. Out of many structures proposed for graphene NEMS, it has been recently shown that a drum resonator exhibits higher Q-factor than other structures such as a bar resonator. However, fabricating a large array of drum graphene resonator has been problematic because liquid or gas can be trapped inside the drum. Such issues led to designs with a hole in the center of a drum or with a drainage trench, either at the cost of additional lithography step or lowered Q-factor. Here, we demonstrate two novel fabrication methods that are free of the trapping without any compromise in additional lithography step or Q-factor degradation. In one method, wafer scale graphene is dry-stamped on prefabricated leads, holes and local gates. In the other method, an resist strip with a circular hole at the center holds graphene underneath. I will discuss direct electrical readout and characterization of devices using these two methods. These drum structures may provide a practical way to achieve wafer scale high Q graphene NEMS.

  11. An activation-collision mechanism for cholesterol transfer between membranes.

    Science.gov (United States)

    Steck, T L; Kezdy, F J; Lange, Y

    1988-09-15

    We report the results of experiments which show that cholesterol transfer between membranes cannot proceed by aqueous diffusion, as widely held, but must involve a more complex mechanism. (a) The rate of transfer of [3H]cholesterol from red blood cells was found to vary inversely with the size of the acceptor particle (ghosts, vesicles of ghosts, liposomes, and plasma lipoproteins). (b) The transfer of [3H]cholesterol from red blood cells to ghosts was accelerated by the presence of plasma, even though the plasma competed with the ghosts as an acceptor. (c) The rate of transfer of [3H]cholesterol from red blood cells to ghosts decreased to zero with increasing dilution but was not simply second-order. (d) The cholesterol in retinal rod disc membranes is not at equilibrium with plasma lipoproteins in that disc cholesterol increased when the homogenates were incubated in vitro with plasma. (e) The kinetics of cholesterol transfer cannot be limited by unstirred layer effects since the transfer of lysolecithin in the same system was faster than that of cholesterol by 3 orders of magnitude. The simplest model compatible with all the data suggests a two-step pathway involving a first-order followed by a second-order process. The first step could be a unimolecular activation event, perhaps the movement of the sterol in the donor particle to a more exposed (hydrated) position. In the second step, the activated sterol would be transferred during transient collisions between donor and acceptor particles. When collision is not rate-limiting, the overall process would appear to be simply first-order, hence kinetically indistinguishable from the aqueous diffusion mechanism. The activation-collision model thus not only rationalizes our data but is also consistent with the simpler kinetics previously reported for the transfer of both membrane phospholipids and sterols.

  12. Combination of electrochemical, spectrometric and other analytical techniques for high throughput screening of pharmaceutically active compounds.

    Science.gov (United States)

    Suzen, Sibel; Ozkan, Sibel A

    2010-08-01

    Recently, use of electrochemistry and combination of this method with spectroscopic and other analytical techniques are getting one of the important approaches in drug discovery and research as well as quality control, drug stability, determination of physiological activity, measurement of neurotransmitters. Many fundamental physiological processes are depending on oxido-reduction reactions in the body. Therefore, it may be possible to find connections between electrochemical and biochemical reactions concerning electron transfer pathways. Applications of electrochemical techniques to redox-active drug development and studies are one of the recent interests in drug discovery. In this review, the latest developments related to the use of electrochemical techniques in drug research in order to evaluate possible combination spectrometric methods with electrochemical techniques.

  13. Role of glutathione transferases in the mechanism of brostallicin activation.

    Science.gov (United States)

    Pezzola, Silvia; Antonini, Giovanni; Geroni, Cristina; Beria, Italo; Colombo, Maristella; Broggini, Massimo; Marchini, Sergio; Mongelli, Nicola; Leboffe, Loris; MacArthur, Robert; Mozzi, Alessia Francesca; Federici, Giorgio; Caccuri, Anna Maria

    2010-01-12

    Brostallicin is a novel and unique glutathione transferase-activated pro-drug with promising anticancer activity, currently in phase I and II clinical evaluation. In this work, we show that, in comparison with the parental cell line showing low GST levels, the cytotoxic activity of brostallicin is significantly enhanced in the human breast carcinoma MCF-7 cell line, transfected with either human GST-pi or GST-mu. Moreover, we describe in detail the interaction of brostallicin with GSH in the presence of GSTP1-1 and GSTM2-2, the predominant GST isoenzymes found within tumor cells. The experiments reported here indicate that brostallicin binds reversibly to both isoenzymes with K(d) values in the micromolar range (the affinity being higher for GSTM2-2). Direct evidence that both GSTP1-1 and GSTM2-2 isoenzymes catalyze the Michael addition reaction of GSH to brostallicin has been obtained both by an HPLC-MS technique and by a new fluorometric assay. We also saw the rapid formation of an intermediate reactive species, which is slowly converted into the final products. This intermediate, identified as the alpha-chloroamido derivative of the GSH-brostallicin adduct, is able to alkylate DNA in a sequence-specific manner and appears to be the active form of the drug. The kinetic behavior of the reaction between brostallicin and GSH, catalyzed by GSTP1-1, has been studied in detail, and a minimum kinetic scheme that suitably describes the experimental data is provided. Overall, these data fully support and extend the findings that brostallicin could be indicated for the treatment of tumor overexpressing the pi or mu class GST.

  14. Prompt Gamma Activation Analysis (PGAA): Technique of choice for nondestructive bulk analysis of returned comet samples

    Science.gov (United States)

    Lindstrom, David J.; Lindstrom, Richard M.

    1989-01-01

    Prompt gamma activation analysis (PGAA) is a well-developed analytical technique. The technique involves irradiation of samples in an external neutron beam from a nuclear reactor, with simultaneous counting of gamma rays produced in the sample by neutron capture. Capture of neutrons leads to excited nuclei which decay immediately with the emission of energetic gamma rays to the ground state. PGAA has several advantages over other techniques for the analysis of cometary materials: (1) It is nondestructive; (2) It can be used to determine abundances of a wide variety of elements, including most major and minor elements (Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Co, Ni), volatiles (H, C, N, F, Cl, S), and some trace elements (those with high neutron capture cross sections, including B, Cd, Nd, Sm, and Gd); and (3) It is a true bulk analysis technique. Recent developments should improve the technique's sensitivity and accuracy considerably.

  15. Effect of Preparation Techniques of Y-Mo/HZSM-5 on Its Activity in Methane Aromatization

    Institute of Scientific and Technical Information of China (English)

    Qiying Wang; Weiming Lin

    2004-01-01

    The production of benzene directly from methane aromatization under oxygen-free condition is currently a new focus in natural gas utilization. The influence of preparation techniques of the catalysts on their catalytic activities is studied in this paper. The influencing factors include the impregnating method, the calcination temperature, the promoter content and the acidity of the zeolite support. Optimum preparation techniques for the catalysts are obtained through this work.

  16. Wet oxidation of activated sludge: transformations and mechanisms.

    Science.gov (United States)

    Urrea, José Luis; Collado, Sergio; Laca, Amanda; Díaz, Mario

    2014-12-15

    Wet oxidation (WO) is an interesting alternative for the solubilization and mineralization of activated sludge. The effects of different temperatures (160-200 °C) and pressures (4-8 MPa), on the evolution of chemical composition and rheological characteristics of a thickened activated sludge during WO are analyzed in this work. Soluble COD increases initially to a maximum and then diminishes, while the apparent viscosity of the mixture falls continuously throughout the experiment. Based on the experimental evolution of the compositions and rheological characteristics of the sludge, a mechanism consisting of two stages in series is proposed. Initially, the solid organic compounds are solubilized following a pseudo-second order kinetic model with respect to solid COD. After that, the solubilized COD was oxidized, showing a pseudofirst kinetic order, by two parallel pathways: the complete mineralization of the organic matter and the formation of highly refractory COD. Kinetic parameters of the model, including the activation energies are mentioned, with good global fitting to the experiments described.

  17. Mechanisms guiding Polycomb activities during gene silencing in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Chongsheng eHe

    2013-11-01

    Full Text Available Polycomb group (PcG proteins act in an evolutionarily conserved epigenetic pathway that regulates chromatin structures in plants and animals, repressing many developmentally important genes by modifying histones. PcG proteins can form at least two multiprotein complexes: Polycomb repressive complexes 1 and 2 (PRC1 and PRC2, respectively. The functions of Arabidopsis thaliana PRCs have been characterized in multiple stages of development and have diverse roles in response to environmental stimuli. Recently, the mechanism that precisely regulates Arabidopsis PcG activity was extensively studied. In this review, we summarize recent discoveries in the regulations of PcG at the three different layers: the recruitment of PRCs to specific target loci, the polyubiquitination and degradation of PRC2, and the antagonism of PRC2 activity by the Trithorax group proteins. Current knowledge indicates that the powerful activity of the PcG pathway is strictly controlled for specific silencing of target genes during plant development and in response to environmental stimuli.

  18. Thermal imaging for detection of SM45C subsurface defects using active infrared thermography techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Yoon Jae; Ranjit, Shrestha; Kim, Won Tae [Kongju National University, Cheonan (Korea, Republic of)

    2015-06-15

    Active thermography techniques have the capability of inspecting a broad range simultaneously. By evaluating the phase difference between the defected area and the healthy area, the technique indicates the qualitative location and size of the defect. Previously, the development of the defect detection method used a variety of materials and the test specimen was done. In this study, the proposed technique of lock-in is verified with artificial specimens that have different size and depth of subsurface defects. Finally, the defect detection capability was evaluated using comparisons of the phase image and the amplitude image according to the size and depth of defects.

  19. A Low Latency Electrocardiographic QRS Activity Recovery Technique for Use on the Upper Left Arm

    Directory of Open Access Journals (Sweden)

    William D. Lynn

    2014-07-01

    Full Text Available Empirical mode decomposition is used as a low latency method of recovering the cardiac ventricular activity QRS biopotential signals recorded from the upper arm. The recovery technique is tested and compared with the industry accepted technique of signal averaging using a database of “normal” rhythm traces from bipolar ECG leads along the left arm, recorded from patient volunteers at a cardiology day procedure clinic. The same partial recomposition technique is applied to recordings taken using an innovative dry electrode technology supplied by Plessey Semiconductors. In each case, signal to noise ratio (SNR is used as a metric for comparison.

  20. Antioxidant activity of Galium mollugo L. extracts obtained by different recovery techniques

    Directory of Open Access Journals (Sweden)

    Milić Petar S.

    2013-01-01

    Full Text Available The yield of extractive substances, antioxidant activity, as well as total phenolic and total flavonoid contents of aqueous-ethanolic extracts obtained from aerial parts of Galium mollugo L. by different extraction techniques (maceration, reflux and ultrasonic extraction were reported. The antioxidant activity of extracts was tested by measuring their ability to scavenge a stable DPPH free radical, while the total phenolic and total flavonoid contents were determined according to the Folin-Ciocalteu procedure and a colorimetric method, respectively. The Duncan’s multiple range tests were used to evaluate if there were significant differences among yields of extractive substances, total phenolics, total flavonoids and EC50 values for the extracts obtained by different extraction techniques. The extracts obtained by the reflux extraction contained higher amounts of extractive substances, as well as phenolic and flavonoid compounds, and showed a better antioxidant activity than those obtained by the two other recovering techniques.

  1. Cooking techniques improve the levels of bioactive compounds and antioxidant activity in kale and red cabbage.

    Science.gov (United States)

    Murador, Daniella Carisa; Mercadante, Adriana Zerlotti; de Rosso, Veridiana Vera

    2016-04-01

    The aim of this study is to investigate the effects of different home cooking techniques (boiling, steaming, and stir-frying) in kale and red cabbage, on the levels of bioactive compounds (carotenoids, anthocyanins and phenolic compounds) determined by high-performance liquid chromatography coupled with photodiode array and mass spectrometry detectors (HPLC-DAD-MS(n)), and on the antioxidant activity evaluated by ABTS, ORAC and cellular antioxidant activity (CAA) assays. The steaming technique resulted in a significant increase in phenolic content in kale (86.1%; pkale, steaming resulted in significant increases in antioxidant activity levels in all of the evaluation methods. In the red cabbage, boiling resulted in a significant increase in antioxidant activity using the ABTS assay but resulted in a significant decrease using the ORAC assay. According to the CAA assay, the stir-fried sample displayed the highest levels of antioxidant activity.

  2. Muscle Energy Technique and Static Stretching for Treatment of Mechanical Neck Pain 16 July 2012 International Journal of Health and Rehabilitation Sciences Volume 1 Number 1 O RIGINAL R ESEARCH Comparative Effectiveness of Muscle Energy Technique and Static Stretching for Treatment of Subacute Mechanical N eck Pain

    Directory of Open Access Journals (Sweden)

    Richa Mahajan

    2012-07-01

    Full Text Available Background: Neck pain is a common problem within our society. Upper trapezius and the levator scapulae are the most common postural muscles that tends to get shorten leading to restricted neck mobility. If these group of muscles are treated it may provide with best results. There is lack of evidence to allow conclusions to be drawn about the effectiveness of Muscle energy technique (MET when compared with stretching exercises for relieving mechanical neck pain. It would be interesting to study if these two techniques yield comparable outcomes and if one technique is superior to the next which should be the alternate choice of therapy Objective: To evaluate the comparative effectiveness of Muscle energy technique and static stretching on pain and active cervical range of motion (ROM in subacute mechanical neck pain Subjects and methods: 45 patients with subacute mechanical neck pain were randomly assigned to receive Muscle Energy Technique plus conventional physiotherapy (group 1, n = 15, static stretching plus conventional exercise program (group 2, n = 15 and conventional physiotherapy only (group 3, n = 15. Intervention: Group 1 received 6 sessions of Muscle Energy Technique and 10 sessions of conventional physiotherapy. Group 2 received 6 sessions of static stretching and 10 sessions of conventional physiotherapy. Group 3 received 10 sessions of conventional physiotherapy. All groups were treated for 2 weeks.Outcome measures:Pain intensity on 100mm VAS, active cervical lateral flexion range of motion, active cervical rotation range of motion. Results: Paired t-test was used for within group analysis. ANOVA followed by post hoc analysis was employed for between group comparisons. No significant difference was found in any of the outcome measure between MET and static stretching groups (p > 0.05 while both were found to be significantly better than the conventional exercise group (p < 0.05 between the 3 groups. Statistically significant

  3. Pulmonary arterioplasty using video-assisted thoracic surgery mechanical suture technique

    Science.gov (United States)

    Xu, Xin; Huang, Jun; Yin, Weiqiang; Zhang, Xin; Chen, Hanzhang; Mo, Lili

    2016-01-01

    Lung cancer invading pulmonary trunk is a locally advanced condition, which may indicate poor prognosis. Surgical resection of the lesion can significantly improve survival for some patients. Lobectomy/Pneumonectomy with pulmonary arterioplasty via thoracotomy were generally accepted and used in the past. As the rapid development of minimally invasive techniques and devices, pulmonary arterioplasty is feasible via video-assisted thoracic surgery (VATS). However, few studies have reported the VATS surgical techniques. In this study, we reported the techniques of pulmonary arterioplasty via VATS. PMID:27076961

  4. Mutant p53: multiple mechanisms define biologic activity in cancer

    Directory of Open Access Journals (Sweden)

    Michael Paul Kim

    2015-11-01

    Full Text Available The functional importance of p53 as a tumor suppressor gene is evident through its pervasiveness in cancer biology. The p53 gene is the most commonly altered gene in human cancer; however, not all genetic alterations are biologically equivalent. The majority of p53 alterations involve missense mutations that result in the production of mutant p53 proteins. Such mutant p53 proteins lack normal p53 function and may acquire novel functions, often with deleterious effects. Here, we review characterized mechanisms of mutant p53 gain of function in multiple model systems. In addition, we review mutant p53 addiction as emerging evidence suggests that tumors may depend on sustained mutant p53 activity for continued growth. We also discuss the role of p53 in stromal elements and their contribution to tumor initiation and progression. Lastly, current genetic mouse models of mutant p53 are reviewed and their limitations discussed.

  5. Conformational Heterogeneity in the Activation Mechanism of Bax.

    Science.gov (United States)

    Barnes, C Ashley; Mishra, Pushpa; Baber, James L; Strub, Marie-Paule; Tjandra, Nico

    2017-08-01

    Bax is known for its pro-apoptotic role within the mitochondrial pathway of apoptosis. However, the mechanism for transitioning Bax from cytosolic to membrane-bound oligomer remains elusive. Previous nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) studies defined monomeric Bax as conformationally homogeneous. Yet it has recently been proposed that monomeric Bax exists in equilibrium with a minor state that is distinctly different from its NMR structure. Here, we revisited the structural analysis of Bax using methods uniquely suited for unveiling "invisible" states of proteins, namely, NMR paramagnetic relaxation enhancements and EPR double electron-electron resonance (DEER). Additionally we examined the effect of glycerol, the co-solvent of choice in DEER studies, on the structure of Bax using NMR chemical-shift perturbations and residual dipolar couplings. Based on our combined NMR and EPR results, Bax is a conformationally homogeneous protein prior to its activation. Published by Elsevier Ltd.

  6. Activation energies of grain growth mechanisms in aluminum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Alan [Lawrence Livermore National Laboratory, Chemistry and Materials Science, CA (United States)]. E-mail: jankowski1@11nl.gov; Ferreira, James [Lawrence Livermore National Laboratory, Chemistry and Materials Science, CA (United States); Hayes, Jeffrey [Lawrence Livermore National Laboratory, Mechanical Engineering, Livermore, CA 94551-9900 (United States)

    2005-11-22

    To produce a specific grain size in metallic coatings requires precise control of the time at temperature during the deposition process. Aluminum coatings are deposited using electron-beam evaporation onto heated substrate surfaces of both mica and lithium flouride. The grain size of the coating is determined upon examination of the microstructure in plan view and cross-section. Ideal grain growth is observed over the entire experimental range of temperature examined from 413 to 843 K. A transition in the activation energy for grain growth from 0.87 to 2.04 eV atom{sup -1} is observed as the temperature increases from < 526 K to > 588 K. The transition is indicative of the dominant mechanism for grain growth shifting with increasing temperature from grain boundary to lattice diffusion.

  7. The activation mechanism of Fe-based olefin metathesis catalysts

    KAUST Repository

    Poater, Albert

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts. © 2014 Elsevier B.V.

  8. Modulatory Mechanism of Nociceptive Neuronal Activity by Dietary Constituent Resveratrol

    Directory of Open Access Journals (Sweden)

    Mamoru Takeda

    2016-10-01

    Full Text Available Changes to somatic sensory pathways caused by peripheral tissue, inflammation or injury can result in behavioral hypersensitivity and pathological pain, such as hyperalgesia. Resveratrol, a plant polyphenol found in red wine and various food products, is known to have several beneficial biological actions. Recent reports indicate that resveratrol can modulate neuronal excitability, including nociceptive sensory transmission. As such, it is possible that this dietary constituent could be a complementary alternative medicine (CAM candidate, specifically a therapeutic agent. The focus of this review is on the mechanisms underlying the modulatory effects of resveratrol on nociceptive neuronal activity associated with pain relief. In addition, we discuss the contribution of resveratrol to the relief of nociceptive and/or pathological pain and its potential role as a functional food and a CAM.

  9. Dynamic Discontinuous Control for Active Control of Mechanical Vibrations

    Directory of Open Access Journals (Sweden)

    Orestes Llanes Santiago

    2010-02-01

    Full Text Available This article shows the use of the discontinuous control using dynamic sliding modes for the active isolation of vibrations in mechanical systems. This type of control law constitutes a robust feedback control policy due to its insensitivity to external disturbance inputs, certain immunity to model parameter variations, within known bounds, and to the ever present modelling errors.  The whole theoretical analysis is applied to a lineal model of two degrees of freedom of the vehicle's suspension where the irregularities of the land represent of direct  way the external interferences to the system . To carry out the isolation an electro-hydraulic operator it is used. Simulations are performed which validate the proposed approach.

  10. A Survey on Optimal Signal Processing Techniques Applied to Improve the Performance of Mechanical Sensors in Automotive Applications

    Science.gov (United States)

    Hernandez, Wilmar

    2007-01-01

    In this paper a survey on recent applications of optimal signal processing techniques to improve the performance of mechanical sensors is made. Here, a comparison between classical filters and optimal filters for automotive sensors is made, and the current state of the art of the application of robust and optimal control and signal processing techniques to the design of the intelligent (or smart) sensors that today's cars need is presented through several experimental results that show that the fusion of intelligent sensors and optimal signal processing techniques is the clear way to go. However, the switch between the traditional methods of designing automotive sensors and the new ones cannot be done overnight because there are some open research issues that have to be solved. This paper draws attention to one of the open research issues and tries to arouse researcher's interest in the fusion of intelligent sensors and optimal signal processing techniques.

  11. Self-burial mechanics of hygroscopically active awns

    Science.gov (United States)

    Jung, Wonjong; Kim, Wonjung; Kim, Ho-Young

    2013-11-01

    We present the results of a combined experimental and theoretical investigation of the mechanics of self-burial of some plant seeds whose morphologies respond to humidity change of the surroundings. The seeds of Pelargonium species have hygroscopically active awns that play a critical role in the dispersal from the parent plant and burial in soil. While the awn uncoils to a linear shape in a highly humid condition, it recoils to a helical shape when dry. The rotation is driven by the structure of the cell walls that are comprised of cellulose microfibers aligned in a tilted helix. During uncoiling of the awn, the revolving tail generates thrust to burrow into soil, so that the seed is self-buried. We present the direct observation of the self-burial of the seed with the thrust into a soft substrate being measured at the same time. The elastica theory allows us to rationalize this botanical digging mechanics using the structural deformations of the hygroexpansive tissues. This work was supported by the Sogang University Research Grant of 2013 (201310009.01) and the National Research Foundation of Korea (grant no. 2012-008023).

  12. Evaluation of physico-mechanical properties of clayey soils using electrical resistivity imaging technique

    Science.gov (United States)

    Kibria, Golam

    Resistivity imaging (RI) is a promising approach to obtaining continuous profile of soil subsurface. This method offers simple technique to identify moisture variation and heterogeneity of the investigated area. However, at present, only qualitative information of subsurface can be obtained using RI. A study on the quantification of geotechnical properties has become important for rigorous use of this method in the evaluation of geohazard potential and construction quality control of landfill liner system. Several studies have been performed to describe electrical resistivity of soil as a function of pore fluid conductivity and surface conductance. However, characterization tests on pore water and surface charge are not typically performed in a conventional geotechnical investigation. The overall objective of this study is to develop correlations between geotechnical parameters and electrical resistivity of soil, which would provide a mean to estimate geotechnical properties from RI. As a part of the study, multiple regression analyses were conducted to develop practically applicable models correlating resistivity with influential geotechnical parameters. The soil samples considered in this study were classified as highly plastic clay (CH) and low plasticity clay (CL) according to Unified Soil Classification System (USCS). Based on the physical tests, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) analysis, kaolinite was identified as the dominant mineral with some traces of magnesium, calcium, potassium, and iron. Electrical resistivity tests were conducted on compacted clays and undisturbed samples under varied geotechnical conditions. The experimental results indicated that the degree of saturation substantially influenced electrical resistivity. Electrical resistivity decreased as much as 11 times from initial value for the increase of degree of saturation from 23 to 100% in the laboratory tests on compacted clays. In case of

  13. Behavior Change Techniques Implemented in Electronic Lifestyle Activity Monitors: A Systematic Content Analysis

    Science.gov (United States)

    Lewis, Zakkoyya H; Mayrsohn, Brian G; Rowland, Jennifer L

    2014-01-01

    Background Electronic activity monitors (such as those manufactured by Fitbit, Jawbone, and Nike) improve on standard pedometers by providing automated feedback and interactive behavior change tools via mobile device or personal computer. These monitors are commercially popular and show promise for use in public health interventions. However, little is known about the content of their feedback applications and how individual monitors may differ from one another. Objective The purpose of this study was to describe the behavior change techniques implemented in commercially available electronic activity monitors. Methods Electronic activity monitors (N=13) were systematically identified and tested by 3 trained coders for at least 1 week each. All monitors measured lifestyle physical activity and provided feedback via an app (computer or mobile). Coding was based on a hierarchical list of 93 behavior change techniques. Further coding of potentially effective techniques and adherence to theory-based recommendations were based on findings from meta-analyses and meta-regressions in the research literature. Results All monitors provided tools for self-monitoring, feedback, and environmental change by definition. The next most prevalent techniques (13 out of 13 monitors) were goal-setting and emphasizing discrepancy between current and goal behavior. Review of behavioral goals, social support, social comparison, prompts/cues, rewards, and a focus on past success were found in more than half of the systems. The monitors included a range of 5-10 of 14 total techniques identified from the research literature as potentially effective. Most of the monitors included goal-setting, self-monitoring, and feedback content that closely matched recommendations from social cognitive theory. Conclusions Electronic activity monitors contain a wide range of behavior change techniques typically used in clinical behavioral interventions. Thus, the monitors may represent a medium by which

  14. Offgas Analysis and Pyrolysis Mechanism of Activated Carbon from Bamboo Sawdust by Chemical Activation With KOH

    Institute of Scientific and Technical Information of China (English)

    TIAN Yong; LIU Ping; WANG Xiufang; ZHONG Guoying; CHEN Guanke

    2011-01-01

    Bamboo sawdust was used as the precursor for the multipurpose use of waste.Offgases released during the activation process of bamboo by KOH were investigated quantitatively and qualitatively by a gas analyzer. TG/DTG curves during the pyrolysis process with different impregnation weight ratios (KOH to bamboo) were obtained by a thermogravimetric analyzer. Pyrolysis mechanism of bamboo was proposed. The results showed that the offgases were composed of CO, NO,SO2 and hydrocarbon with the concentration of 1 372, 37, 86, 215 mg/L, respectively. Thermogravimetric analysis indicated that the pyrolytic process mainly experienced two steps. The first was the low temperature activation step (lower than 300 ℃), which was the pre-activation and induction period.The second was the high temperature activation step(higher than 550 ℃), which was a radial activation followed by pore production. The second process was the key to control the pore distribution of the final product.

  15. Partial Agonists Activate PPARgamma Using a Helix 12 Independent Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Bruning, J.B.; Chalmers, M.J.; Prasad, S.; Bushby, S.A.; Kamenecka, T.A.; He, Y.; Nettles, K.W.; Griffin, P.R.

    2009-05-28

    Binding to helix 12 of the ligand-binding domain of PPAR{gamma} is required for full agonist activity. Previously, the degree of stabilization of the activation function 2 (AF-2) surface was thought to correlate with the degree of agonism and transactivation. To examine this mechanism, we probed structural dynamics of PPAR{gamma} with agonists that induced graded transcriptional responses. Here we present crystal structures and amide H/D exchange (HDX) kinetics for six of these complexes. Amide HDX revealed each ligand induced unique changes to the dynamics of the ligand-binding domain (LBD). Full agonists stabilized helix 12, whereas intermediate and partial agonists did not at all, and rather differentially stabilized other regions of the binding pocket. The gradient of PPAR{gamma} transactivation cannot be accounted for solely through changes to the dynamics of AF-2. Thus, our understanding of allosteric signaling must be extended beyond the idea of a dynamic helix 12 acting as a molecular switch.

  16. Mechanisms of Physical Activity Limitation in Chronic Lung Diseases

    Directory of Open Access Journals (Sweden)

    Ioannis Vogiatzis

    2012-01-01

    Full Text Available In chronic lung diseases physical activity limitation is multifactorial involving respiratory, hemodynamic, and peripheral muscle abnormalities. The mechanisms of limitation discussed in this paper relate to (i the imbalance between ventilatory capacity and demand, (ii the imbalance between energy demand and supply to working respiratory and peripheral muscles, and (iii the factors that induce peripheral muscle dysfunction. In practice, intolerable exertional symptoms (i.e., dyspnea and/or leg discomfort are the main symptoms that limit physical performance in patients with chronic lung diseases. Furthermore, the reduced capacity for physical work and the adoption of a sedentary lifestyle, in an attempt to avoid breathlessness upon physical exertion, cause profound muscle deconditioning which in turn leads to disability and loss of functional independence. Accordingly, physical inactivity is an important component of worsening the patients’ quality of life and contributes importantly to poor prognosis. Identifying the factors which prevent a patient with lung disease to easily carry out activities of daily living provides a unique as well as important perspective for the choice of the appropriate therapeutic strategy.

  17. Molecular mechanism of APC/C activation by mitotic phosphorylation.

    Science.gov (United States)

    Zhang, Suyang; Chang, Leifu; Alfieri, Claudio; Zhang, Ziguo; Yang, Jing; Maslen, Sarah; Skehel, Mark; Barford, David

    2016-05-12

    In eukaryotes, the anaphase-promoting complex (APC/C, also known as the cyclosome) regulates the ubiquitin-dependent proteolysis of specific cell-cycle proteins to coordinate chromosome segregation in mitosis and entry into the G1 phase. The catalytic activity of the APC/C and its ability to specify the destruction of particular proteins at different phases of the cell cycle are controlled by its interaction with two structurally related coactivator subunits, Cdc20 and Cdh1. Coactivators recognize substrate degrons, and enhance the affinity of the APC/C for its cognate E2 (refs 4-6). During mitosis, cyclin-dependent kinase (Cdk) and polo-like kinase (Plk) control Cdc20- and Cdh1-mediated activation of the APC/C. Hyperphosphorylation of APC/C subunits, notably Apc1 and Apc3, is required for Cdc20 to activate the APC/C, whereas phosphorylation of Cdh1 prevents its association with the APC/C. Since both coactivators associate with the APC/C through their common C-box and Ile-Arg tail motifs, the mechanism underlying this differential regulation is unclear, as is the role of specific APC/C phosphorylation sites. Here, using cryo-electron microscopy and biochemical analysis, we define the molecular basis of how phosphorylation of human APC/C allows for its control by Cdc20. An auto-inhibitory segment of Apc1 acts as a molecular switch that in apo unphosphorylated APC/C interacts with the C-box binding site and obstructs engagement of Cdc20. Phosphorylation of the auto-inhibitory segment displaces it from the C-box-binding site. Efficient phosphorylation of the auto-inhibitory segment, and thus relief of auto-inhibition, requires the recruitment of Cdk-cyclin in complex with a Cdk regulatory subunit (Cks) to a hyperphosphorylated loop of Apc3. We also find that the small-molecule inhibitor, tosyl-l-arginine methyl ester, preferentially suppresses APC/C(Cdc20) rather than APC/C(Cdh1), and interacts with the binding sites of both the C-box and Ile-Arg tail motifs. Our

  18. Mechanical stress activates neurites and somata of myenteric neurons

    Directory of Open Access Journals (Sweden)

    Eva Maria Kugler

    2015-09-01

    Full Text Available The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN, slowly (SAMEN or ultra-slowly (USAMEN. The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut.

  19. Nonlinear techniques for forecasting solar activity directly from its time series

    Science.gov (United States)

    Ashrafi, S.; Roszman, L.; Cooley, J.

    1993-01-01

    This paper presents numerical techniques for constructing nonlinear predictive models to forecast solar flux directly from its time series. This approach makes it possible to extract dynamical in variants of our system without reference to any underlying solar physics. We consider the dynamical evolution of solar activity in a reconstructed phase space that captures the attractor (strange), give a procedure for constructing a predictor of future solar activity, and discuss extraction of dynamical invariants such as Lyapunov exponents and attractor dimension.

  20. Changes in muscle activation following balance and technique training and a season of Australian football.

    Science.gov (United States)

    Donnelly, C J; Elliott, B C; Doyle, T L A; Finch, C F; Dempsey, A R; Lloyd, D G

    2015-05-01

    Determine if balance and technique training implemented adjunct to 1001 male Australian football players' training influenced the activation/strength of the muscles crossing the knee during pre-planned and unplanned sidestepping. Randomized Control Trial. Each Australian football player participated in either 28 weeks of balance and technique training or 'sham' training. Twenty-eight Australian football players (balance and technique training, n=12; 'sham' training, n=16) completed biomechanical testing pre-to-post training. Peak knee moments and directed co-contraction ratios in three degrees of freedom, as well as total muscle activation were calculated during pre-planned and unplanned sidestepping. No significant differences in muscle activation/strength were observed between the 'sham' training and balance and technique training groups. Following a season of Australian football, knee extensor (p=0.023) and semimembranosus (p=0.006) muscle activation increased during both pre-planned sidestepping and unplanned sidestepping. Following a season of Australian football, total muscle activation was 30% lower and peak valgus knee moments 80% greater (p=0.022) during unplanned sidestepping when compared with pre-planned sidestepping. When implemented in a community level training environment, balance and technique training was not effective in changing the activation of the muscles crossing the knee during sidestepping. Following a season of Australian football, players are better able to support both frontal and sagittal plane knee moments. When compared to pre-planned sidestepping, Australian football players may be at increased risk of anterior cruciate ligament injury during unplanned sidestepping in the latter half of an Australian football season. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  1. A new technique in constructing closed-form solutions for nonlinear PDEs appearing in fluid mechanics and gas dynamics

    Directory of Open Access Journals (Sweden)

    D. E. Panayotounakos

    1996-01-01

    Full Text Available We develop a new unique technique in constructing closed-form solutions for several nonlinear partial differential systems appearing in fluid mechanics and gas dynamics. The obtained solutions include fewer arbitrary functions than needed for general solutions, fact that permits us to specify them according to the initial state, or the geometry, of each specific problem under consideration. In order to apply the before mentioned technique we construct closed-form solutions concerning the gas-dynamic equations with constant pressure, the dynamic equations of an ideal gas in isentropic flow, and the two-dimensional incompressible boundary layer flow.

  2. A new technique in constructing closed-form solutions for nonlinear PDEs appearing in fluid mechanics and gas dynamics

    Directory of Open Access Journals (Sweden)

    Panayotounakos D. E.

    1996-01-01

    Full Text Available We develop a new unique technique in constructing closed-form solutions for several nonlinear partial differential systems appearing in fluid mechanics and gas dynamics. The obtained solutions include fewer arbitrary functions than needed for general solutions, fact that permits us to specify them according to the initial state, or the geometry, of each specific problem under consideration. In order to apply the before mentioned technique we construct closed-form solutions concerning the gas-dynamic equations with constant pressure, the dynamic equations of an ideal gas in isentropic flow, and the two-dimensional incompressible boundary layer flow.

  3. An Active Damping Technique for Small DC-Link Capacitor Based Drive System

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Lu, Kaiyuan

    2013-01-01

    A small dc-link capacitor based drive system shows instability when it is operated with large input line inductance at operating points with high power. This paper presents a simple, new active damping technique that can stabilize effectively the drive system at unstable operating points, offering...

  4. Status of the Usage of Active Learning and Teaching Method and Techniques by Social Studies Teachers

    Science.gov (United States)

    Akman, Özkan

    2016-01-01

    The purpose of this study was to determine the active learning and teaching methods and techniques which are employed by the social studies teachers working in state schools of Turkey. This usage status was assessed using different variables. This was a case study, wherein the research was limited to 241 social studies teachers. These teachers…

  5. Regulation on the Appraisal Activities of The Products,Techniques and Applications Projects of BIRTV

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    I General Provisions 1.The Appraisal Activities of the Products,Techniques andApplications Projects of BIRTV is held for the purpose of strengthen-ing the technical advisory work and pilot role,and providing positiveguidance and effective assistance in the field of new technology

  6. Partial root drying irrigation technique: Practical application of drought stress signaling mechanism in plants

    Directory of Open Access Journals (Sweden)

    Savić Slađana

    2009-01-01

    Full Text Available Partial root-zone drying (PRD technique, a novel approach to watering crops, was developed on the basis of knowledge of root-to-shoot signaling in drying soil. The aim of the present paper was to investigate the effects of the PRD treatment on tomato growth and the water regime. The obtained PRD results showed significant reduction in shoot but not fruit growth in the absence of any changes in shoot water status, indicating the involvement of chemical root-to-shoot signals. Higher water use efficiency (WUE results mean that the PRD technique can be used to reduce irrigation water without significant reduction of tomato yield.

  7. Probing cell structure responses through a shear and stretching mechanical stimulation technique.

    Science.gov (United States)

    Steward, Robert L; Cheng, Chao-Min; Wang, Danny L; LeDuc, Philip R

    2010-04-01

    Cells are complex, dynamic systems that respond to various in vivo stimuli including chemical, mechanical, and scaffolding alterations. The influence of mechanics on cells is especially important in physiological areas that dictate what modes of mechanics exist. Complex, multivariate physiological responses can result from multi-factorial, multi-mode mechanics, including tension, compression, or shear stresses. In this study, we present a novel device based on elastomeric materials that allowed us to stimulate NIH 3T3 fibroblasts through uniaxial strip stretching or shear fluid flow. Cell shape and structural response was observed using conventional approaches such as fluorescent microscopy. Cell orientation and actin cytoskeleton alignment along the direction of applied force were observed to occur after an initial 3 h time period for shear fluid flow and static uniaxial strip stretching experiments although these two directions of alignment were oriented orthogonal relative to each other. This response was then followed by an increasingly pronounced cell and actin cytoskeleton alignment parallel to the direction of force after 6, 12, and 24 h, with 85% of the cells aligned along the direction of force after 24 h. These results indicate that our novel device could be implemented to study the effects of multiple modes of mechanical stimulation on living cells while probing their structural response especially with respect to competing directions of alignment and orientation under these different modes of mechanical stimulation. We believe that this will be important in a diversity of fields including cell mechanotransduction, cell-material interactions, biophysics, and tissue engineering.

  8. Equine preantral follicles obtained via the Biopsy Pick-Up method: histological evaluation and validation of a mechanical isolation technique.

    Science.gov (United States)

    Haag, K T; Magalhães-Padilha, D M; Fonseca, G R; Wischral, A; Gastal, M O; King, S S; Jones, K L; Figueiredo, J R; Gastal, E L

    2013-03-15

    The aims of this study in mares were to: (1) compare preantral follicle parameters between in vitro Biopsy Pick-Up (BPU) and scalpel blade collection methods and between histological and mechanical isolation processing (experiment 1); (2) histologically evaluate preantral follicles (experiment 2); and (3) compare histological analysis with a previously established mechanical isolation technique using a tissue chopper (experiment 3) for ovarian cortical fragments obtained in vivo using a BPU instrument. In experiment 1, preantral follicles were analyzed (N = 220; 90% primordial and 10% primary). Proportions of primordial and primary follicles did not differ (P > 0.05) between tissue collection (BPU vs. scalpel blade dissection) or processing (mechanical isolation vs. histology) methods. Follicle viability and morphology rates were similar (P > 0.05) between tissue collection methods, but mechanical isolation produced more (P 0.05) by processing methods. In conclusion, most parameters evaluated for preantral follicles were similar between histological and tissue chopper processing techniques; hence, mechanical isolation efficiently dissociated equine preantral follicles from the ovarian cortex. Therefore, the tissue chopper could be used to isolate large numbers of morphologically normal equine preantral follicles for cryopreservation and/or in vitro culture.

  9. PEEP-ZEEP technique: cardiorespiratory repercussions in mechanically ventilated patients submitted to a coronary artery bypass graft surgery

    Directory of Open Access Journals (Sweden)

    Auler José

    2011-09-01

    Full Text Available Abstract Background The PEEP-ZEEP technique is previously described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP, followed by rapid lung deflation with an abrupt reduction in the PEEP to 0 cmH2O (ZEEP, associated to a manual bilateral thoracic compression. Aim To analyze PEEP-ZEEP technique's repercussions on the cardio-respiratory system in immediate postoperative artery graft bypass patients. Methods 15 patients submitted to a coronary artery bypass graft surgery (CABG were enrolled prospectively, before, 10 minutes and 30 minutes after the technique. Patients were curarized, intubated, and mechanically ventilated. To perform PEEP-ZEEP technique, saline solution was instilled into their orotracheal tube than the patient was reconnected to the ventilator. Afterwards, the PEEP was increased to 15 cmH2O throughout 5 ventilatory cycles and than the PEEP was rapidly reduced to 0 cmH2O along with manual bilateral thoracic compression. At the end of the procedure, tracheal suction was accomplished. Results The inspiratory peak and plateau pressures increased during the procedure (p Conclusion The PEEP-ZEEP technique seems to be safe, without alterations on hemodynamic variables, produces elevated expiratory flow and seems to be an alternative technique for the removal of bronchial secretions in patients submitted to a CABG.

  10. Opioid-Induced Glial Activation: Mechanisms of Activation and Implications for Opioid Analgesia, Dependence, and Reward

    Directory of Open Access Journals (Sweden)

    Mark R. Hutchinson

    2007-01-01

    Full Text Available This review will introduce the concept of toll-like receptor (TLR–mediated glial activation as central to all of the following: neuropathic pain, compromised acute opioid analgesia, and unwanted opioid side effects (tolerance, dependence, and reward. Attenuation of glial activation has previously been demonstrated both to alleviate exaggerated pain states induced by experimental pain models and to reduce the development of opioid tolerance. Here we demonstrate that selective acute antagonism of TLR4 results in reversal of neuropathic pain as well as potentiation of opioid analgesia. Attenuating central nervous system glial activation was also found to reduce the development of opioid dependence, and opioid reward at a behavioral (conditioned place preference and neurochemical (nucleus accumbens microdialysis of morphine-induced elevations in dopamine level of analysis. Moreover, a novel antagonism of TLR4 by (+- and (˗-isomer opioid antagonists has now been characterized, and both antiallodynic and morphine analgesia potentiating activity shown. Opioid agonists were found to also possess TLR4 agonistic activity, predictive of glial activation. Targeting glial activation is a novel and as yet clinically unexploited method for treatment of neuropathic pain. Moreover, these data indicate that attenuation of glial activation, by general or selective TLR antagonistic mechanisms, may also be a clinical method for separating the beneficial (analgesia and unwanted (tolerance, dependence, and reward actions of opioids, thereby improving the safety and efficacy of their use.

  11. The Compu-pet 100: a versatile dispenser-diluter for the mechanization of microbiological techniques.

    Science.gov (United States)

    Cremer, A W; Mellars, B; Stokes, E J

    1975-01-01

    The Compu-pet 100 diluter/dispenser is a versatile and accurate instrument which can be employed for a wide variety of microbiological tests and techniques. Time in performing tests is often more than halved when the diluter is used. Large numbers of tests can be performed with minimal fatigue.

  12. A comparative study between standard dry needling technique and rapid dry needling technique on active gluteus medius muscle trigger points

    OpenAIRE

    2012-01-01

    M.Tech. This study aimed to determine the difference between the standard dry needling technique versus the rapid dry needling technique with regards to which technique would provide quicker relief of symptoms, as measured by an increase in participant’s pressure tolerance and range of motion and a decrease in subjective pain. Subjectively it was seen that both groups had a statistical decrease in the participants perceived pain with the Oswestry Disability Index, the McGill’s Pain Questio...

  13. Study of the aging processes in polyurethane adhesives using thermal treatment and differential calorimetric, dielectric, and mechanical techniques ; 1, identifying the aging processes ; 2, quantifying the aging effect

    CERN Document Server

    Althouse, L P

    1979-01-01

    Study of the aging processes in polyurethane adhesives using thermal treatment and differential calorimetric, dielectric, and mechanical techniques ; 1, identifying the aging processes ; 2, quantifying the aging effect

  14. Prediction of activity type in preschool children using machine learning techniques.

    Science.gov (United States)

    Hagenbuchner, Markus; Cliff, Dylan P; Trost, Stewart G; Van Tuc, Nguyen; Peoples, Gregory E

    2015-07-01

    Recent research has shown that machine learning techniques can accurately predict activity classes from accelerometer data in adolescents and adults. The purpose of this study is to develop and test machine learning models for predicting activity type in preschool-aged children. Participants completed 12 standardised activity trials (TV, reading, tablet game, quiet play, art, treasure hunt, cleaning up, active game, obstacle course, bicycle riding) over two laboratory visits. Eleven children aged 3-6 years (mean age=4.8±0.87; 55% girls) completed the activity trials while wearing an ActiGraph GT3X+ accelerometer on the right hip. Activities were categorised into five activity classes: sedentary activities, light activities, moderate to vigorous activities, walking, and running. A standard feed-forward Artificial Neural Network and a Deep Learning Ensemble Network were trained on features in the accelerometer data used in previous investigations (10th, 25th, 50th, 75th and 90th percentiles and the lag-one autocorrelation). Overall recognition accuracy for the standard feed forward Artificial Neural Network was 69.7%. Recognition accuracy for sedentary activities, light activities and games, moderate-to-vigorous activities, walking, and running was 82%, 79%, 64%, 36% and 46%, respectively. In comparison, overall recognition accuracy for the Deep Learning Ensemble Network was 82.6%. For sedentary activities, light activities and games, moderate-to-vigorous activities, walking, and running recognition accuracy was 84%, 91%, 79%, 73% and 73%, respectively. Ensemble machine learning approaches such as Deep Learning Ensemble Network can accurately predict activity type from accelerometer data in preschool children. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  15. Combination of analytical and microbiological techniques to study the antimicrobial activity of a new active food packaging containing cinnamon or oregano against E. coli and S. aureus.

    Science.gov (United States)

    Becerril, R; Gómez-Lus, R; Goñi, P; López, P; Nerín, C

    2007-07-01

    The aim of this work is the optimization and application of a group of analytical and microbiological techniques in the study of the activity of essential oils (EOs) incorporated in a new antimicrobial packaging material and the research in depth of the interaction between the microbial cells and the individual compounds present in the active material. For this purpose the antimicrobial activity of the active packaging containing cinnamon or oregano was evaluated against E. coli and S. aureus. The vapour phase activity and the direct contact between the antimicrobial agents themselves, or once incorporated in the packaging material, and the microbial cells have been studied. The direct contact was studied using a broth dilution method. The vapour phase was evaluated by using a new method which involves the use of a filter disk containing the EOs. Furthermore, the kill time assay was used to determine the exposure time for the maximum efficiency in packaging, and transmission electron microscopy was used to investigate the antimicrobial activity and the possible mechanism of action against E. coli and S. aureus. Finally, the compounds absorbed by cells were identified. The results showed that the techniques used provide relevant information about the antibacterial activity of cinnamon and oregano in direct contact as well as in the vapour phase. The antimicrobial packaging showed a fast efficiency which supports its likely application as a food packaging material. Bacteria treated with EOs exhibit a wide range of significant abnormalities; these include formation of blebs, coagulation of cytoplasmatic constituents, collapse of the cell structure and lack of cytoplasmatic material. Some of these observations are correlated to the ability of some of these substances to disrupt envelop structure, especially the inner membrane. After an extraction from dead cells, cinnamaldehyde was detected by GC-MS in E. coli exposed to the active packaging containing cinnamon.

  16. Glutathione transferase classes alpha, pi, and mu: GSH activation mechanism.

    Science.gov (United States)

    Dourado, Daniel F A R; Fernandes, Pedro Alexandrino; Ramos, Maria João

    2010-10-14

    Since the early 1960s, glutathione transferases (GSTs) have been described as detoxification enzymes. In fact, GSTs are the most important enzymes involved in the metabolism of electrophilic xenobiotic/endobiotic compounds. These enzymes are able to catalyze the nucleophilic addition of glutathione (GSH) sulfur thiolate to a wide range of electrophilic substrates, building up a less toxic and more soluble compound. Cytosolic classes alpha, pi, and mu are the most extensively studied GSTs. However, many of the catalytic events are still poorly understood. In the present work, we have resorted to density functional theory (DFT) and to potential of mean force (PMF) calculations to determine the GSH activation mechanism of GSTP1-1 and GSTM1-1 isoenzymes. For the GSTP1-1 enzyme, we have demonstrated that a water molecule, after an initial conformational rearrangement of GSH, can assist a proton transfer between the GSH cysteine thiol (GSH-SH) and the GSH glutamate alpha carboxylate (GSH-COO(-)) groups. The energy barrier associated with the proton transfer is 11.36 kcal·mol(-1). The GSTM1-1 enzyme shows a completely different behavior from the previous isoenzyme. In this case, two water molecules, positioned between the GSH-SH and the ξ N atom of His107, working like a bridge, are able to promote the proton transfer between these two active groups with an energy barrier of 7.98 kcal·mol(-1). All our results are consistent with all the enzymes kinetics and mutagenesis experimental studies.

  17. Daphne oleoides Schreber ssp. oleoides Exhibits Potent Wound Healing Effect: Isolation of the Active Components and Elucidation of the Activity Mechanism

    Directory of Open Access Journals (Sweden)

    Ipek Süntar

    2014-03-01

    Full Text Available Ethnobotanical surveys revealed that Daphne oleoidesSchreber has been used against rheumatic pain and for wound healing in Turkish folk medicine. The aim of the present study is to verify the folkloric assertion of D. oleoides ssp. oleoides (DOO by bioassay-guided fractionation procedures leading to determination of the active component(s and to elucidate the activity mechanisms of the isolated compounds. The wound healing activity of the methanol extract, its subextracts, fractions and isolates was evaluated by using two different in vivo wound healing experimental techniques . Anti-inflammatory and antioxidant activities of the test materials were also evaluated. For the determination of the activity mechanisms, the isolated compounds were screened for hyaluronidase, collagenase and elastase enzyme inhibitory activities. The methanolic extract of DOO was found to possess potent wound healing activity. This extract was then subjected to successive solvent extractions with n-hexane, dichloromethane, ethyl acetate (EtOAc and n-butanol. EtOAc subextract yielded three compounds, quercetin 3-O-glucoside, triumbellin and rutarensin by using chromatographic separation techniques. The experimental study revealed that D. oleoides subsp. oleoides methanolic extract possesses significant wound healing effect and quercetin 3-O-glucoside was determined as the active component responsible from the activity.

  18. Performance Evaluation a Developed Energy Harvesting Interface Circuit in Active Technique

    Directory of Open Access Journals (Sweden)

    Ramizi Mohamed

    2014-10-01

    Full Text Available This study presents the performance evaluation a developed energy harvesting interface circuit in active technique. The energy harvesting interface circuit for micro-power applications uses equivalent voltage of the piezoelectric materials have been developed and simulated. Circuit designs and simulation results are presented for a conventional diode rectifier with voltage doubler in passive technique. Most of the existing techniques are mainly passive-based energy harvesting circuits. Generally, the power harvesting capability of the passive technique is very low. To increase the harvested energy, the active technique and its components such as MOSFET, thyristor and transistor have chosen to design the proposed energy harvesting interface circuit. In this study, it has simulated both the conventional in passive circuit and developed energy harvester in active technique. The developed interface circuits consisting of piezoelectric element with input source of vibration, AC-DC thyristor doubler rectifier circuit and DC-DC boost converter using thyristor with storage device. In the development circuits, it is noted that the components thyristor instead of mainly diode available in conventional circuits have chosen. Because the forward voltage potential (0.7 V is higher than the incoming input voltage (0.2 V. Finally, the complete energy harvester using PSPICE software have designed and simulated. The proposed circuits in PSPICE generate the boost-up DC voltage up to 2 V. The overall efficiency of the developed circuit is 70%, followed by the software simulation, which is greater than conventional circuit efficiency of 20% in performance evaluator. It is concluded that the developed circuit output voltage can be used to operate for the applications in autonomous devices.

  19. Antibacterial activity and mechanism of berberine against Streptococcus agalactiae.

    Science.gov (United States)

    Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

    2015-01-01

    The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually.

  20. Inhibition mechanism of Tb(III) on horseradish peroxidase activity.

    Science.gov (United States)

    Guo, Shaofen; Zhou, Qing; Lu, Tianhong; Ding, Xiaolan; Huang, Xiaohua

    2008-10-01

    The inhibition mechanism of Tb(III) on horseradish peroxidase (HRP) in vitro was discussed. The results from MALDI-TOF/MS and X-ray photoelectron spectroscopy (XPS) showed that Tb(III) mainly interacts with the O-containing groups of the amides in the polypeptide chains of the HRP molecules and forms the complex of Tb(III)-HRP, and, in the complex, the molar ratio Tb(III)/HRP is 2 : 1. The results from CD and atomic force microscopy (AFM) indicated that the coordination effect between Tb(III) and HRP can lead to the conformation change in the HRP molecule, in which the contents of alpha-helix and beta-sheet conformation in the peptide of the HRP molecules is decreased, and the content of the random coil conformation is increased. Meanwhile, the coordination effect also leads to the decrease in the content of inter- and intrapeptide-chain H-bonds in the HRP molecules, resulting in the HRP molecular looseness and/or aggregation. Thus, the conformation change in the HRP molecules can significantly decrease the electrochemical reaction of HRP and its electrocatalytic activity for the reduction of H2O2.

  1. Activated sludge characterization through microscopy: A review on quantitative image analysis and chemometric techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Daniela P. [IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Amaral, A. Luís [IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Instituto Politécnico de Coimbra, ISEC, DEQB, Rua Pedro Nunes, Quinta da Nora, 3030-199 Coimbra (Portugal); Ferreira, Eugénio C., E-mail: ecferreira@deb.uminho.pt [IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2013-11-13

    Graphical abstract: -- Highlights: •Quantitative image analysis shows potential to monitor activated sludge systems. •Staining techniques increase the potential for detection of operational problems. •Chemometrics combined with quantitative image analysis is valuable for process monitoring. -- Abstract: In wastewater treatment processes, and particularly in activated sludge systems, efficiency is quite dependent on the operating conditions, and a number of problems may arise due to sludge structure and proliferation of specific microorganisms. In fact, bacterial communities and protozoa identification by microscopy inspection is already routinely employed in a considerable number of cases. Furthermore, quantitative image analysis techniques have been increasingly used throughout the years for the assessment of aggregates and filamentous bacteria properties. These procedures are able to provide an ever growing amount of data for wastewater treatment processes in which chemometric techniques can be a valuable tool. However, the determination of microbial communities’ properties remains a current challenge in spite of the great diversity of microscopy techniques applied. In this review, activated sludge characterization is discussed highlighting the aggregates structure and filamentous bacteria determination by image analysis on bright-field, phase-contrast, and fluorescence microscopy. An in-depth analysis is performed to summarize the many new findings that have been obtained, and future developments for these biological processes are further discussed.

  2. UPDATING OF THE ANATOMY OF THE EXTENSOR MECHANISM OF THE KNEE USING A THREE-DIMENSIONAL VIEWING TECHNIQUE.

    Science.gov (United States)

    Astur, Diego Costa; Oliveira, Saulo Gomes; Badra, Ricardo; Arliani, Gustavo Gonçalves; Kaleka, Camila Cohen; Jalikjian, Wahi; Golanó, Pau; Cohen, Moisés

    2011-01-01

    The knee extensor mechanism is a complex structure formed by the quadriceps muscle and tendon, the patella, the patellar tendon and the ligaments that surround and help stabilize the knee. Through using a three-dimensional viewing technique on images of the knee extensor apparatus, we aimed to didactically show the structures that compose this bone-muscle-ligament complex. Anatomical dissection of the knee with emphasis on the structures of its extensor mechanism was performed, followed by taking photographs using a camera and lenses suitable for simulating human vision, through a technique for constructing three-dimensional images. Then, with the aid of appropriate software, pairs of images of the same structure from different angles simulating human vision were overlain with the addition of polarizing layer, thereby completing the construction of an anaglyphic image. The main structures of the knee extensor mechanism could be observed with a three-dimensional effect. Among the main benefits relating to this technique, we can highlight that in addition to teaching and studying musculoskeletal anatomy, it has potential use in training for surgical procedures and production of images for diagnostic tests.

  3. Development of a novel technique to assess the vulnerability of micro-mechanical system components to environmentally assisted cracking.

    Energy Technology Data Exchange (ETDEWEB)

    Enos, David George; Goods, Steven Howard

    2006-11-01

    Microelectromechanical systems (MEMS) will play an important functional role in future DOE weapon and Homeland Security applications. If these emerging technologies are to be applied successfully, it is imperative that the long-term degradation of the materials of construction be understood. Unlike electrical devices, MEMS devices have a mechanical aspect to their function. Some components (e.g., springs) will be subjected to stresses beyond whatever residual stresses exist from fabrication. These stresses, combined with possible abnormal exposure environments (e.g., humidity, contamination), introduce a vulnerability to environmentally assisted cracking (EAC). EAC is manifested as the nucleation and propagation of a stable crack at mechanical loads/stresses far below what would be expected based solely upon the materials mechanical properties. If not addressed, EAC can lead to sudden, catastrophic failure. Considering the materials of construction and the very small feature size, EAC represents a high-risk environmentally induced degradation mode for MEMS devices. Currently, the lack of applicable characterization techniques is preventing the needed vulnerability assessment. The objective of this work is to address this deficiency by developing techniques to detect and quantify EAC in MEMS materials and structures. Such techniques will allow real-time detection of crack initiation and propagation. The information gained will establish the appropriate combinations of environment (defining packaging requirements), local stress levels, and metallurgical factors (composition, grain size and orientation) that must be achieved to prevent EAC.

  4. Articular dysfunction patterns in patients with mechanical neck pain: a clinical algorithm to guide specific mobilization and manipulation techniques.

    Science.gov (United States)

    Dewitte, Vincent; Beernaert, Axel; Vanthillo, Bart; Barbe, Tom; Danneels, Lieven; Cagnie, Barbara

    2014-02-01

    In view of a didactical approach for teaching cervical mobilization and manipulation techniques to students as well as their use in daily practice, it is mandatory to acquire sound clinical reasoning to optimally apply advanced technical skills. The aim of this Masterclass is to present a clinical algorithm to guide (novice) therapists in their clinical reasoning to identify patients who are likely to respond to mobilization and/or manipulation. The presented clinical reasoning process is situated within the context of pain mechanisms and is narrowed to and applicable in patients with a dominant input pain mechanism. Based on key features in subjective and clinical examination, patients with mechanical nociceptive pain probably arising from articular structures can be categorized into specific articular dysfunction patterns. Pending on these patterns, specific mobilization and manipulation techniques are warranted. The proposed patterns are illustrated in 3 case studies. This clinical algorithm is the corollary of empirical expertise and is complemented by in-depth discussions and knowledge exchange with international colleagues. Consequently, it is intended that a carefully targeted approach contributes to an increase in specificity and safety in the use of cervical mobilizations and manipulation techniques as valuable adjuncts to other manual therapy modalities.

  5. Relationship between Pore-size Distribution and Flexibility of Adsorbent Materials: Statistical Mechanics and Future Material Characterization Techniques.

    Science.gov (United States)

    Siderius, Daniel W; Mahynski, Nathan A; Shen, Vincent K

    2017-05-01

    Measurement of the pore-size distribution (PSD) via gas adsorption and the so-called "kernel method" is a widely used characterization technique for rigid adsorbents. Yet, standard techniques and analytical equipment are not appropriate to characterize the emerging class of flexible adsorbents that deform in response to the stress imparted by an adsorbate gas, as the PSD is a characteristic of the material that varies with the gas pressure and any other external stresses. Here, we derive the PSD for a flexible adsorbent using statistical mechanics in the osmotic ensemble to draw analogy to the kernel method for rigid materials. The resultant PSD is a function of the ensemble constraints including all imposed stresses and, most importantly, the deformation free energy of the adsorbent material. Consequently, a pressure-dependent PSD is a descriptor of the deformation characteristics of an adsorbent and may be the basis of future material characterization techniques. We discuss how, given a technique for resolving pressure-dependent PSDs, the present statistical mechanical theory could enable a new generation of analytical tools that measure and characterize certain intrinsic material properties of flexible adsorbents via otherwise simple adsorption experiments.

  6. Phospholipid Membrane Protection by Sugar Molecules during Dehydration—Insights into Molecular Mechanisms Using Scattering Techniques

    Science.gov (United States)

    Garvey, Christopher J.; Lenné, Thomas; Koster, Karen L.; Kent, Ben; Bryant, Gary

    2013-01-01

    Scattering techniques have played a key role in our understanding of the structure and function of phospholipid membranes. These techniques have been applied widely to study how different molecules (e.g., cholesterol) can affect phospholipid membrane structure. However, there has been much less attention paid to the effects of molecules that remain in the aqueous phase. One important example is the role played by small solutes, particularly sugars, in protecting phospholipid membranes during drying or slow freezing. In this paper, we present new results and a general methodology, which illustrate how contrast variation small angle neutron scattering (SANS) and synchrotron-based X-ray scattering (small angle (SAXS) and wide angle (WAXS)) can be used to quantitatively understand the interactions between solutes and phospholipids. Specifically, we show the assignment of lipid phases with synchrotron SAXS and explain how SANS reveals the exclusion of sugars from the aqueous region in the particular example of hexagonal II phases formed by phospholipids. PMID:23584028

  7. Phospholipid Membrane Protection by Sugar Molecules during Dehydration-Insights into Molecular Mechanisms Using Scattering Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Garvey, Christopher J.; Lenné, Thomas; Koster, Karen L.; Kent, Ben; Bryant, Gary [ANSTO; (USD); (ANU); (RMIT)

    2014-09-24

    Scattering techniques have played a key role in our understanding of the structure and function of phospholipid membranes. These techniques have been applied widely to study how different molecules (e.g., cholesterol) can affect phospholipid membrane structure. However, there has been much less attention paid to the effects of molecules that remain in the aqueous phase. One important example is the role played by small solutes, particularly sugars, in protecting phospholipid membranes during drying or slow freezing. In this paper, we present new results and a general methodology, which illustrate how contrast variation small angle neutron scattering (SANS) and synchrotron-based X-ray scattering (small angle (SAXS) and wide angle (WAXS)) can be used to quantitatively understand the interactions between solutes and phospholipids. Specifically, we show the assignment of lipid phases with synchrotron SAXS and explain how SANS reveals the exclusion of sugars from the aqueous region in the particular example of hexagonal II phases formed by phospholipids.

  8. Fluid Dynamic Analysis of Shaken and Mechanically Stirred Reactors by Means of Optical Techniques

    OpenAIRE

    Pieralisi, Irene

    2016-01-01

    This research aims at deepening the knowledge of the hydrodynamics developing within some specific mixing system configurations. In particular, a standard geometry stirred vessel, an unbaffled stirred vessel of unconventional geometry and a shaken bioreactor are studied. Optical techniques (LDA, PIV) are employed in order to obtain detailed information on the mean and turbulent characteristics of the flow developing within the different lab-scale reactors, while subsequent data analysis a...

  9. Estimation of Fracture Length as a Mechanical Property in Hydrofraturing Technique using an Experimental Setup

    Directory of Open Access Journals (Sweden)

    B. Guruprasad

    2012-12-01

    Full Text Available This paper compares temperature distribution and weld bead profiles of constant current and pulsed current gas tungsten arc welded AISI 304L grade stainless steel joints. The effects of pulsed current welding on tensile properties, hardness profiles, micro structural features and residual stress distribution of stainless steel joints are reported. The use of pulsed current technique improves the tensile properties of the welds compared to those of continuous current welds due to grain refinement occurring in the fusion zone.

  10. Detection of active faults using EMR-Technique and Cerescope at Landau area in central Upper Rhine Graben, SW Germany

    Science.gov (United States)

    Hagag, Wael; Obermeyer, Hennes

    2016-01-01

    Two conjugate sets of active faults oriented NNE-SSW and NNW-SSE have been detected at Landau area in SW Germany. These faults follow the old trends of the rift-related structures predominating in the Upper Rhine Graben (URG), which originated during Late Eocene-Miocene time. Linear and horizontal measurements were performed by using the Cerescope device and interpreted, applying the Electromagnetic Radiation (EMR) Technique. Linear EMR-profiles were helpful for mapping active faults, while the main horizontal stress (σH, N to NNE) was easily identified with EMR-horizontal measurements. Reactivation of rift-related structures of the Upper Rhine Graben at Landau area produces a new system of active shallow fractures following old trends, and has been detected through the present study by Cerescope applying the EMR-Technique. The present results imply that the Enhanced Geothermal System (EGS) to the south of Landau has a great impact on reactivation of the pre-existing rift-related faults by mechanical hydro-fracturing occurring within the reservoir rocks underneath the area.

  11. The dynamical activation-relaxation technique (DART): an on-the-fly kinetic Monte-Carlo algorithm

    Science.gov (United States)

    El-Mellouhi, Fadwa; Cote, Michel; Lewis, Laurent J.; Mousseau, Normand

    2008-03-01

    We present DART, the dynamical activation-relaxation technique, that combines the activation-relaxation technique (ART nouveau) with a non-lattice KMC method that allows the on-the-fly identification of barriers and the full treatment of lattice deformations. Most KMC schemes rely on the use of a fixed list of events and barriers, which are drawn with the proper weight during the simulation. While this works well for a number of problems (such as metal-on-metal growth), it cannot be used for processes where the events may change with time. DART overcomes this limitation. ART nouveau has been used extensively for the study of activated mechanisms in different materials within both an empirical and an ab-initio description of the systems. In the DART implementation, KMC moves are based on a catalog of events constructed on-the-fly using ART. After each KMC move, this catalog is updated so as to take into account new environments that may appear. A topological description of the structure of the system at each moment allows the method to identify rapidly these new environments and to move forward efficiently. In this talk, we will describe the method and present the case of interstitial diffusion in Si. Our results are compared with previous molecular-dynamics and on-lattice KMC simulations.

  12. Refolding techniques for recovering biologically active recombinant proteins from inclusion bodies.

    Science.gov (United States)

    Yamaguchi, Hiroshi; Miyazaki, Masaya

    2014-02-20

    Biologically active proteins are useful for studying the biological functions of genes and for the development of therapeutic drugs and biomaterials in a biotechnology industry. Overexpression of recombinant proteins in bacteria, such as Escherichia coli, often results in the formation of inclusion bodies, which are protein aggregates with non-native conformations. As inclusion bodies contain relatively pure and intact proteins, protein refolding is an important process to obtain active recombinant proteins from inclusion bodies. However, conventional refolding methods, such as dialysis and dilution, are time consuming and, often, recovered yields of active proteins are low, and a trial-and-error process is required to achieve success. Recently, several approaches have been reported to refold these aggregated proteins into an active form. The strategies largely aim at reducing protein aggregation during the refolding procedure. This review focuses on protein refolding techniques using chemical additives and laminar flow in microfluidic chips for the efficient recovery of active proteins from inclusion bodies.

  13. Experimental Study of Active Techniques for Blade/Vortex Interaction Noise Reduction

    Science.gov (United States)

    Kobiki, Noboru; Murashige, Atsushi; Tsuchihashi, Akihiko; Yamakawa, Eiichi

    This paper presents the experimental results of the effect of Higher Harmonic Control (HHC) and Active Flap on the Blade/Vortex Interaction (BVI) noise. Wind tunnel tests were performed with a 1-bladed rotor system to evaluate the simplified BVI phenomenon avoiding the complicated aerodynamic interference which is characteristically and inevitably caused by a multi-bladed rotor. Another merit to use this 1-bladed rotor system is that the several objective active techniques can be evaluated under the same condition installed in the same rotor system. The effects of the active techniques on the BVI noise reduction were evaluated comprehensively by the sound pressure, the blade/vortex miss distance obtained by Laser light Sheet (LLS), the blade surface pressure distribution and the tip vortex structure by Particle Image Velocimetry (PIV). The correlation among these quantities to describe the effect of the active techniques on the BVI conditions is well obtained. The experiments show that the blade/vortex miss distance is more dominant for BVI noise than the other two BVI governing factors, such as blade lift and vortex strength at the moment of BVI.

  14. Measurements of fusion neutron yields by neutron activation technique: Uncertainty due to the uncertainty on activation cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Stankunas, Gediminas, E-mail: gediminas.stankunas@lei.lt [Lithuanian Energy Institute, Laboratory of Nuclear Installation Safety, Breslaujos str. 3, LT-44403 Kaunas (Lithuania); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Batistoni, Paola [ENEA, Via E. Fermi, 45, 00044 Frascati, Rome (Italy); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Sjöstrand, Henrik; Conroy, Sean [Department of Physics and Astronomy, Uppsala University, PO Box 516, SE-75120 Uppsala (Sweden); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2015-07-11

    The neutron activation technique is routinely used in fusion experiments to measure the neutron yields. This paper investigates the uncertainty on these measurements as due to the uncertainties on dosimetry and activation reactions. For this purpose, activation cross-sections were taken from the International Reactor Dosimetry and Fusion File (IRDFF-v1.05) in 640 groups ENDF-6 format for several reactions of interest for both 2.5 and 14 MeV neutrons. Activation coefficients (reaction rates) have been calculated using the neutron flux spectra at JET vacuum vessel, both for DD and DT plasmas, calculated by MCNP in the required 640-energy group format. The related uncertainties for the JET neutron spectra are evaluated as well using the covariance data available in the library. These uncertainties are in general small, but not negligible when high accuracy is required in the determination of the fusion neutron yields.

  15. Mechanism for activation of the growth factor-activated AGC kinases by turn motif phosphorylation

    DEFF Research Database (Denmark)

    Hauge, Camilla; Antal, Torben L; Hirschberg, Daniel

    2007-01-01

    investigated the role of the third, so-called turn motif phosphate, also located in the tail, in the AGC kinases PKB, S6K, RSK, MSK, PRK and PKC. We report cooperative action of the HM phosphate and the turn motif phosphate, because it binds a phosphoSer/Thr-binding site above the glycine-rich loop within...... the kinase domain, promoting zipper-like association of the tail with the kinase domain, serving to stabilize the HM in its kinase-activating binding site. We present a molecular model for allosteric activation of AGC kinases by the turn motif phosphate via HM-mediated stabilization of the alphaC helix. In S......6K and MSK, the turn motif phosphate thereby also protects the HM from dephosphorylation. Our results suggest that the mechanism described is a key feature in activation of upto 26 human AGC kinases....

  16. Fabrication of polystyrene/agave particle biocomposites using compression molding technique: evaluation of flammability, biodegradability, mechanical and thermal behaviour

    Indian Academy of Sciences (India)

    A S Singha; Raj K Rana

    2013-12-01

    Polystyrene (PS) composites reinforced with ungrafted and acrylonitrile (AN) grafted agave particles (AgP) have been prepared with 10–30% particle content by weight using compression molding technique. The composite specimens thus prepared were subjected to the evaluation of mechanical, chemical, flammability and biodegradability properties. PS composites with 20% particle loading exhibited optimum mechanical properties. AN grafted AgP/PS composites exhibited higher mechanical strength as compared to ungrafted AgP/PS composites. Further AN grafted AgP/PS composites exhibited better thermal properties and biodegradability as compared to PS matrix. Addition of fire retardant fillers such as magnesium hydroxide Mg(OH)2 and zinc borate lowered burning rate of PS composites considerably. Scanning electron microscopy (SEM) of tensile fracture surfaces of AN grafted AgP/PS composites showed better particle/matrix adhesion.

  17. Cross- And Up-selling Techniques In E-Commerce Activities

    Directory of Open Access Journals (Sweden)

    Bernard F. Kubiak

    2010-12-01

    Full Text Available In the article the Cross- and Up-selling marketing techniques were presented in the spectrum of e-commerce. Their aim is to raise both the value of a single sales transaction and confidence as well as to lower the risk of ta king the customers by the competitors. In the article iterative client service model was presented, indicating particular roles of the Cross- and Up-selling techniques in the processes of automation and integration marketing activities In the context of customer relationship managem ent those are of great importance as they give reasons for conducting effective advertisement, promotion and loyal campaigns. The work is finished by summary in which authors pay attention to economic advantages resulting from using presented techniques

  18. Salvia officinalis for hot flushes: towards determination of mechanism of activity and active principles.

    Science.gov (United States)

    Rahte, Sinikka; Evans, Richard; Eugster, Philippe J; Marcourt, Laurence; Wolfender, Jean-Luc; Kortenkamp, Andreas; Tasdemir, Deniz

    2013-06-01

    Herbal medicinal products are commonly used in alternative treatment of menopausal hot flushes. In a recent clinical study, Salvia officinalis tincture was found to reduce hot flush frequency and intensity. The aim of the current study was the investigation of the mechanism(s) responsible for the anti-hot flush activity of S. officinalis and determination of its active principle(s). The 66% ethanolic tincture, as well as the n-hexane, CHCl₃, and aqueous ethanolic subextracts obtained from the tincture were studied in vitro for two of the most relevant activities, estrogenicity and selective serotonin reuptake inhibition. Because of an increased risk of menopausal women to suffer from Alzheimer's disease, an in vitro acetylcholinesterase inhibition assay was also employed. No activity was observed in the selective serotonin reuptake inhibition or the acetylcholinesterase inhibition assays at the highest test concentrations. The tincture showed no estrogenic effects whereas the aqueous ethanolic subextract exhibited estrogenicity in the ERLUX assay with an EC₅₀ value of 64 µg/mL. Estrogenic activity-guided fractionation of the aqueous ethanolic subextract by a combination of reverse-phase vacuum liquid chromatography and gel chromatography identified luteolin-7-O-glucuronide (EC₅₀ 129 µg/mL) as the active component of the vacuum liquid chromatography fraction 4 (EC₅₀ 69 µg/mL). Luteolin-7-O-glucoside was identified as the putative estrogenic principle of the most potent minor fraction (7.6.7.6, EC₅₀ 0.7 µg/mL) obtained from the initial vacuum liquid chromatography fraction 7 (EC₅₀ 3 µg/mL). This study suggests the involvement of common and ubiquitous estrogenic flavonoids in the anti-hot flush effect of Salvia officinalis, a safe and commonly used herbal medicinal product during the menopause.

  19. Insights into the phosphatase and the synthase activities of human bisphosphoglycerate mutase: a quantum mechanics/molecular mechanics simulation.

    Science.gov (United States)

    Chu, Wen-Ting; Zheng, Qing-Chuan; Zhang, Hong-Xing

    2014-03-07

    Bisphosphoglycerate mutase (BPGM) is a multi-activity enzyme. Its main function is to synthesize the 2,3-bisphosphoglycerate, the allosteric effector of hemoglobin. This enzyme can also catalyze the 2,3-bisphosphoglycerate to the 3-phosphoglycerate. In this study, the reaction mechanisms of both the phosphatase and the synthase activities of human bisphosphoglycerate mutase were theoretically calculated by using the quantum mechanics/molecular mechanics method based on the metadynamics and umbrella sampling simulations. The simulation results not only show the free energy curve of the phosphatase and the synthase reactions, but also reveal the important role of some residues in the active site. Additionally, the energy barriers of the two reactions indicate that the activity of the synthase in human bisphosphoglycerate mutase is much higher than that of the phosphatase. The estimated reaction barriers are consistent with the experimental data. Therefore, our work can give important information to understand the catalytic mechanism of the bisphosphoglycerate mutase family.

  20. Dense Nanostructured Nickel Produced by SPS from Mechanically Activated Powders: Enhancement of Mechanical Properties

    Directory of Open Access Journals (Sweden)

    F. Naimi

    2013-01-01

    Full Text Available An investigation was performed to evaluate the potential of the spark plasma sintering process in producing dense nanostructured materials. Microstructured and nanostructured nickel was sintered by SPS starting from nickel powder (APS 3–7 m in the as-received state and after a mechanical activation using a high-energy ball mill. First, a sintering study to determine SPS processing conditions to reach full densification was carried out with specimens 50 mm in diameter and 10 mm in height. In a second step, an experimental investigation was undertaken with dense nickel disks to generate tensile properties. The tensile tests were performed at a strain rate of 10−3 s−1 with specimens 16 mm in gage length and 4 mm in gage diameter. Tensile ductility in excess of 40% was reached with the microstructured nickel. For the nanostructured nickel, high yield stresses in excess of 600 MPa were measured with a tensile ductility of 30%. These results were analyzed through densification and microstructure measurements.

  1. Mechanical Prevention of Post-ERCP Pancreatitis by Pancreatic Stents: Results, Techniques, and Indications

    Directory of Open Access Journals (Sweden)

    Tarnasky PR

    2003-01-01

    Full Text Available Impaired pancreatic drainage may be most important in the pathophysiology of post-ERCP pancreatitis. When there is a mechanical problem, there is often a mechanical solution. Pancreatic stenting reduces the incidence and severity of post-ERCP pancreatitis in high-risk patients. Young patients with suspected sphincter of Oddi dysfunction or prior pancreatitis and those undergoing procedures with either a difficult cannulation, precut and/or pancreatic sphincterotomy should be strongly considered for pancreatic stenting. Stents should be removed within about one week or have the proximal flaps removed to allow early spontaneous distal migration. Pancreatic stent placement following biliary intervention can occasionally be difficult. In cases where the primary goal is pancreatic therapy, one should consider establishing pancreatic access before addressing the bile duct. A pancreatic stent can then serve as a guide for sphincterotomy, but most importantly, protect against post-ERCP pancreatitis.

  2. Figure analysis: A teaching technique to promote visual literacy and active Learning.

    Science.gov (United States)

    Wiles, Amy M

    2016-07-08

    Learning often improves when active learning techniques are used in place of traditional lectures. For many of these techniques, however, students are expected to apply concepts that they have already grasped. A challenge, therefore, is how to incorporate active learning into the classroom of courses with heavy content, such as molecular-based biology courses. An additional challenge is that visual literacy is often overlooked in undergraduate science education. To address both of these challenges, a technique called figure analysis was developed and implemented in three different levels of undergraduate biology courses. Here, students learn content while gaining practice in interpreting visual information by discussing figures with their peers. Student groups also make connections between new and previously learned concepts on their own while in class. The instructor summarizes the material for the class only after students grapple with it in small groups. Students reported a preference for learning by figure analysis over traditional lecture, and female students in particular reported increased confidence in their analytical abilities. There is not a technology requirement for this technique; therefore, it may be utilized both in classrooms and in nontraditional spaces. Additionally, the amount of preparation required is comparable to that of a traditional lecture. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(4):336-344, 2016. © 2016 The International Union of Biochemistry and Molecular Biology.

  3. Flight Performance Handbook for Orbital Operations: Orbital Mechanics and Astrodynamics Formulae, Theorems, Techniques, and Applications

    Science.gov (United States)

    Ambrosio, Alphonso; Blitzer, Leon; Conte, S.D.; Cooper, Donald H.; Dergarabedian, P.; Dethlefsen, D.G.; Lunn, Richard L.; Ireland, Richard O.; Jensen, Arnold A.; Kang, Garfield; Levy, Ezra C.; Liu, Anthony; Marcus, Silvia R.; Mickelwait, A.B.; Moe, Kenneth; Moe, Mildred M.; Pitton, A.R.; Scheuer, Ernest M.; Tompkins, E.H.; Weiser, Peter B.; Whitford, R.K.; Wolverton, R.W.

    1961-01-01

    This handbook provides parametric data useful both to the space vehicle designer and mission analyst. It provides numerical and analytical relationships between missions and gross vehicle characteristics as a function of performance parameters. The effects of missile constraints and gross guidance limitations plus operational constraints such as launch site location, tracking net location, orbit visibility and mission on trajectory and orbit design parameters are exhibited. The influence of state-of- the-art applications of solar power as compared to future applications of nuclear power on orbit design parameters, such as eclipse time, are among the parameters included in the study. The principal aim, however, is in providing the analyst with useful parametric design information to cover the general area of earth satellite missions in the region of near-earth to cislunar space and beyond and from injection to atmospheric entry and controlled descent. The chapters are organized around the central idea of orbital operations in the 1961-1969 era with emphasis on parametric flight mechanics studies for ascent phase and parking orbits, transfer maneuvers, rendezvous maneuver, operational orbit considerations, and operational orbit control. The results are based almost entirely on the principles of flight and celestial mechanics. Numerous practical examples have been worked out in detail. This is especially important where it has been difficult or impossible to represent all possible variations of the parameters. The handbook contains analytical formulae and sufficient textual material to permit their proper use. The analytic methods consist of both exact and rapid, approximate methods. Scores of tables, working graphs and illustrations amplify the mathematical models which, together with important facts and data, cover the engineering and scientific applications of orbital mechanics. Each of the five major chapters are arranged to provide a rapid review of an entire

  4. A code-independent technique for computational verification of fluid mechanics and heat transfer problems

    Institute of Scientific and Technical Information of China (English)

    M. Garbey; C. Picard

    2008-01-01

    The goal of this paper is to present a versatile framework for solution verification of PDE's.We first generalize the Richardson Extrapolation technique to an optimized extrapolation solution procedure that constructs the best consistent solution from a set of two or three coarse grid solution in the discrete norm of choice. This technique generalizes the Least Square Extrapolation method introduced by one of the author and W. Shyy. We second establish the conditioning number of the problem in a reduced space that approximates the main feature of the numerical solution thanks to a sensitivity analysis. Overall our method produces an a posteriori error estimation in this reduced space of approximation. The key feature of our method is that our construction does not require an internal knowledge of the software neither the source code that produces the solution to be verified. It can be applied in principle as a postprocessing procedure to off the shelf commercial code. We demonstrate the robustness of our method with two steady problems that are separately an incompressible back step flow test case and a heat transfer problem for a battery. Our error estimate might be ultimately verified with a near by manufactured solution. While our procedure is systematic and requires numerous computation of residuals, one can take advantage of distributed computing to get quickly the error estimate.

  5. Stress recovery techniques for natural element method in 2-D solid mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin Rae [Dept. of Naval Architecture and Ocean Engineering, Hongik University, Sejong (Korea, Republic of)

    2016-11-15

    This paper is concerned with the stress recovery for the natural element method in which the problem domain is discretized with Delaunay triangles and the structural behavior is approximated with Laplace interpolation functions. Basically, the global and local patch recovery techniques based on the L2-projection method are adopted. For the local patch recovery, the local element patches are defined by the supports of each Laplace interpolation function. For the comparison purpose, the local stress recovery is also performed using Lagrange-type basis functions that are used for 3- and 6-node triangular elements. The stresses that are recovered by the present global and local recovery techniques are compared each other and compared with the available analytic solution, in terms of their spatial distributions and the convergence rates. As well, the dependence of the recovered stress field on the type of test basis functions that are used forbnov-Galerkin (BG) and Petrov-Galerkin (PG) natural element methods is also investigated.

  6. Theoretical and Numerical Experiences on a Test Rig for Active Vibration Control of Mechanical Systems with Moving Constraints

    Directory of Open Access Journals (Sweden)

    M. Rinchi

    2004-01-01

    Full Text Available Active control of vibrations in mechanical systems has recently benefited of the remarkable development of robust control techniques. These control techniques are able to guarantee performances in spite of unavoidable modeling errors. They have been successfully codified and implemented for vibrating structures whose uncertain parameters could be assumed to be time-invariant. Unfortunately a wide class of mechanical systems, such as machine tools with carriage motion realized by a ball-screw, are characterized by time varying modal parameters. The focus of this paper is on modeling and controlling the vibrations of such systems. A test rig for active vibration control is presented. An analytical model of the test rig is synthesized starting by design data. Through experimental modal analysis, parametric identification and updating procedures, the model has been refined and a control system has been synthesized.

  7. The effects of communication techniques on public relation activities: A sample of hospitality business

    OpenAIRE

    Şirvan Şen Demir

    2011-01-01

    Nowadays, firms who give importance to public relations have been increasing rapidly in numbers. All modern firms either found public relations department in their body to deal with public relations operations or outsource this activity to consultants in order to communicate with target populations. Among the firms in tourism sector, hospitality companies are the ones that use public relations the most. The purpose of this study is to investigate the communication techniques in public relatio...

  8. Dynamics Analysis of a Three-DOF Planar Serial-Parallel Mechanism for Active Dynamic Balancing with Respect to a Given Trajectory

    Directory of Open Access Journals (Sweden)

    Kun Wang

    2013-01-01

    Full Text Available The concept of dynamic balancing with respect to a given trajectory is proposed in this paper. Trajectory‐based dynamic balancing is a technique that brings additional mechanisms to unbalanced mechanisms with the purpose of actuating the original mechanism to move along a predefined trajectory, regardless of the shaking forces and moments. In this work, a planar three degrees of freedom (3‐DOF serial‐parallel mechanism is proposed to implement this technique on an unbalanced platform. The overall structure of the system is firstly introduced and the mechanical design and kinematics of the proposed mechanism is then presented. The dynamic model of the mechanism and the platform is derived and analysed. Finally, numerical examples are presented to verify the effectiveness of the active dynamic balancing mechanism and the improved dynamic performance of the system.

  9. Dynamics Analysis of a Three-DOF Planar Serial-Parallel Mechanism for Active Dynamic Balancing with Respect to a Given Trajectory

    Directory of Open Access Journals (Sweden)

    Kun Wang

    2013-01-01

    Full Text Available The concept of dynamic balancing with respect to a given trajectory is proposed in this paper. Trajectory-based dynamic balancing is a technique that brings additional mechanisms to unbalanced mechanisms with the purpose of actuating the original mechanism to move along a predefined trajectory, regardless of the shaking forces and moments. In this work, a planar three degrees of freedom (3-DOF serial-parallel mechanism is proposed to implement this technique on an unbalanced platform. The overall structure of the system is firstly introduced and the mechanical design and kinematics of the proposed mechanism is then presented. The dynamic model of the mechanism and the platform is derived and analysed. Finally, numerical examples are presented to verify the effectiveness of the active dynamic balancing mechanism and the improved dynamic performance of the system.

  10. Enhancement of bimetallic Fe-Mn/CNTs nano catalyst activity and product selectivity using microemulsion technique

    Institute of Scientific and Technical Information of China (English)

    Zahra; Zolfaghari; Ahmad; Tavasoli; Saber; Tabyar; Ali; Nakhaei; Pour

    2014-01-01

    Bimetallic Fe-Mn nano catalysts supported on carbon nanotubes(CNTs) were prepared using microemulsion technique with water-to-surfactant ratios of 0.4-1.6. The nano catalysts were extensively characterized by different methods and their activity and selectivity in Fischer-Tropsch synthesis(FTS) have been assessed in a fixed-bed microreactor. The physicochemical properties and performance of the nanocatalysts were compared with the catalyst prepared by impregnation method. Very narrow particle size distribution has been produced by the microemulsion technique at relatively high loading of active metal. TEM images showed that small metal nano particles in the range of 3–7 nm were not only confined inside the CNTs but also located on the outer surface of the CNTs. Using microemulsion technique with water to surfactant ratio of0.4 decreased the average iron particle sizes to 5.1 nm. The reduction percentage and dispersion percentage were almost doubled. Activity and selectivity were found to be dependent on the catalyst preparation method and average iron particle size. CO conversion and FTS rate increased from 49.1% to 71.0% and 0.144 to 0.289 gHC/(gcat h), respectively. While the WGS rate decreased from 0.097 to 0.056 gCO2/(gcat h). C5+liquid hydrocarbons selectivity decreased slightly and olefins selectivity almost doubled.

  11. Effects of nanosuspension and inclusion complex techniques on the in vitro protease inhibitory activity of naproxen

    Energy Technology Data Exchange (ETDEWEB)

    Dharmalingam, Senthil Rajan; Chidambaram, Kumarappan; Srinivasan, Ramamurthy; Nadaraju, Shamala, E-mail: dsenthilrajan@yahoo.co.in [School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur (Malaysia)

    2014-01-15

    This study investigated the effects of nanosuspension and inclusion complex techniques on in vitro trypsin inhibitory activity of naproxen—a member of the propionic acid derivatives, which are a group of antipyretic, analgesic, and non-steroidal anti-inflammatory drugs. Nanosuspension and inclusion complex techniques were used to increase the solubility and anti-inflammatory efficacy of naproxen. The evaporative precipitation into aqueous solution (EPAS) technique and the kneading methods were used to prepare the nanosuspension and inclusion complex of naproxen, respectively. We also used an in vitro protease inhibitory assay to investigate the anti-inflammatory effect of modified naproxen formulations. Physiochemical properties of modified naproxen formulations were analyzed using UV, IR spectra, and solubility studies. Beta-cyclodextrin inclusion complex of naproxen was found to have a lower percentage of antitryptic activity than a pure nanosuspension of naproxen did. In conclusion, nanosuspension of naproxen has a greater anti-inflammatory effect than the other two tested formulations. This is because the nanosuspension formulation reduces the particle size of naproxen. Based on these results, the antitryptic activity of naproxen nanosuspension was noteworthy; therefore, this formulation can be used for the management of inflammatory disorders. (author)

  12. Study of microstress state of P91 steel using complementary mechanical Barkhausen, magnetoacoustic emission, and X-ray diffraction techniques

    Science.gov (United States)

    Augustyniak, Bolesław; Piotrowski, Leszek; Maciakowski, Paweł; Chmielewski, Marek; Lech-Grega, Marzena; Żelechowski, Janusz

    2014-05-01

    The paper deals with assessment of microstress state of martensite P91 steel using three complementary techniques: mechanical Barkhausen emission, magnetoacoustic emission (MAE), and X-ray diffraction (XRD) profile analysis. Magnetic coercivity Hc and microstructure were investigated with inductive magnetometry and magnetic force microscopy (MFM), respectively. Internal stress level of P91 steel was modified by heat treatment. Steel samples were austenitized, quenched, and then tempered at three temperatures (720 °C, 750 °C, and 780 °C) during increasing time (from 15 min up to 240 min). The microstrain level ɛi was evaluated using Williamson-Hall method. It was revealed that during tempering microstrain systematically decreases from ɛi = 2.5 × 10-3 for as quenched state down to ɛi = 0.3 × 10-3 for well tempered samples. Both mechanical hardness (Vicker's HV) and magnetic hardness (coercivity) decrease almost linearly with decreasing microstrain while the MAE and MBE intensities strongly increase. Tempering leads to evident shift of the MeBN intensity maximum recorded for the first load towards lower applied strain values and to increase of MAE intensity. This indicates that the microstress state deduced by magnetic techniques is correlated with microstrains evaluated with XRD technique.

  13. Study of microstress state of P91 steel using complementary mechanical Barkhausen, magnetoacoustic emission, and X-ray diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Augustyniak, Bolesław, E-mail: bolek@mif.pg.gda.pl; Piotrowski, Leszek; Maciakowski, Paweł; Chmielewski, Marek [Faculty of Applied Physics and Mathematics, Gdansk University of Technology, 80-233 Gdansk (Poland); Lech-Grega, Marzena; Żelechowski, Janusz [The Institute of Non-Ferrous Metals, 32-050 Skawina (Poland)

    2014-05-07

    The paper deals with assessment of microstress state of martensite P91 steel using three complementary techniques: mechanical Barkhausen emission, magnetoacoustic emission (MAE), and X-ray diffraction (XRD) profile analysis. Magnetic coercivity Hc and microstructure were investigated with inductive magnetometry and magnetic force microscopy (MFM), respectively. Internal stress level of P91 steel was modified by heat treatment. Steel samples were austenitized, quenched, and then tempered at three temperatures (720 °C, 750 °C, and 780 °C) during increasing time (from 15 min up to 240 min). The microstrain level ε{sub i} was evaluated using Williamson–Hall method. It was revealed that during tempering microstrain systematically decreases from ε{sub i} = 2.5 × 10{sup −3} for as quenched state down to ε{sub i} = 0.3 × 10{sup −3} for well tempered samples. Both mechanical hardness (Vicker's HV) and magnetic hardness (coercivity) decrease almost linearly with decreasing microstrain while the MAE and MBE intensities strongly increase. Tempering leads to evident shift of the MeBN intensity maximum recorded for the first load towards lower applied strain values and to increase of MAE intensity. This indicates that the microstress state deduced by magnetic techniques is correlated with microstrains evaluated with XRD technique.

  14. Barrier and uptake mechanisms in the cerebrovascular response to noradrenaline. [/sup 133/Xe tracer technique, baboons

    Energy Technology Data Exchange (ETDEWEB)

    McCalden, T.A.; Eidelman, B.H.; Mendelow, A.D.

    1977-10-01

    Cerebral blood flow (CBF) was measured in 20 baboons by the intra-arterial xenon-133 injection method. The CBF responses to intra-arterial infusions of noradrenaline (NA) were determined. These responses were normally found to be vasodilator and mediated by beta adrenoreceptors. After infusion of substances blocking extraneuronal uptake of NA or opening of the blood-brain barrier, this vasodilation was either abolished or converted to an alpha-receptor mediated vasoconstriction. This suggests that normally the cerebral circulation is protected against noradrenergic vasoconstriction by mechanisms reducing the concentration of NA in the tunica media to below threshold for alpha-adrenoreceptor stimulation.

  15. Condensed tannins from Ficus virens as tyrosinase inhibitors: structure, inhibitory activity and molecular mechanism.

    Directory of Open Access Journals (Sweden)

    Xiao-Xin Chen

    Full Text Available Condensed tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark condensed tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the condensed tannins were studied. The results indicated that the condensed tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark condensed tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the condensed tannins on the diphenolase activity were further investigated. The results indicated that the condensed tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the condensed tannins could chelate the dicopper irons of the enzyme. Moreover, the condensed tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.

  16. Effect of welding techniques on microstructure and mechanical properties of aluminium-lithium alloy welds

    Energy Technology Data Exchange (ETDEWEB)

    Madhusudhan Reddy, G.; Gokhale, A.A.; Saxena, V.K. [Defence Metallurgical Research Lab., Hyderabad (India); Prasad Rao, K.

    2000-07-01

    The tensile properties and fatigue crack growth behaviour of sheets of an Al-1.9Li-1.8Cu-1.0 Mg-0.1Zr alloy welded under different conditions were evaluated. The basic welding technique was constant current (CC) gas tungsten arc (GTA) welding. Two modifications viz. pulsed current (PC) and magnetic arc oscillation (AO) were introduced to study effects on microstructure and properties. Both PC and AO resulted in microstructural refinement in the fusion zone. The tensile residual stresses present in CC welds reduced when either PC or AO welding was used. The tensile strength and ductility increased, and fatigue crack growth rates lowered when PC or AO conditions replaced CC welding. (orig.)

  17. A Comparative Study of the Physical and Mechanical Properties of Hydrogen Using Data Mining Research Techniques

    Science.gov (United States)

    Settouti, Nadera; Aourag, Hafid

    2015-09-01

    Hydrogen was the first element to exist in the universe. It is the lightest and simplest element, but chemists do not agree about its placement in the periodic table; its position has given rise to much confusion. Metallization of hydrogen under high pressure influences its properties and its placement in the periodic table. The properties of groups I, IV, and VII are investigated, and are then compared to those of hydrogen. In this study, we present a data mining approach to determine models and discover the similarities included in the datasets. Principal component analysis and partial least squares regression were applied as data analysis techniques in order to explore multivariate data. Our results indicate that hydrogen shares some properties with certain elements and groups in the periodic table, such as carbon group elements, but not entirely, because hydrogen is still considered as an element that is special and apart.

  18. A non-contact mechanical solution for implementing synchronized switching techniques for energy harvesting using reed switches

    Science.gov (United States)

    Shih, Ya Shan; Vasic, Dejan; Jong Wu, Wen

    2016-12-01

    In this work we proposed a new mechanical method of implementing the synchronized switching technique for piezoelectric energy harvesting based on reed switches. Serving as a mechanical displacement monitor and the switch itself, it holds the merit of non-contact, persistence, and the low voltage threshold of merely a single PN junction. However, as all mechanical switches inherits chattering, or bouncing, energy loss and damping on the inversion was caused. To side pass the chattering, three types of electro-mechanical hybrid switches were furthermore developed to stabilize the interfered current flow: resistor-capacitor snubbers, inductor-capacitor snubbers, and silicon controlled rectifiers (SCRs). Each of the method has its merit and suitable working conditions. Comparing to conventional electrical switches, the proposed switches, greatly reduced the switch impedance since the mechanical switch part provides a physically open switch, and the electrical switch part merely consist of either a diode and a MOSFET pair, or a single SCR. Subsequently, the power loss due to the circuit was efficiently eliminated.

  19. Experimental Investigation on the Mechanical Behavior of Bovine Bone Using Digital Image Correlation Technique

    Directory of Open Access Journals (Sweden)

    Yuxi Chen

    2015-01-01

    Full Text Available In order to understand the fracture mechanisms of bone subjected to external force well, an experimental study has been performed on the bovine bone by carrying out the three-point bending test with 3D digital image correlation (DIC method, which provides a noncontact and full field of displacement measurement. The local strain and damage evolution of the bone has been recorded real time. The results show that the deflection measured by DIC agrees well with that obtained by the displacement sensor of the mechanical testing machine. The relationship between the deflection and the force is nearly linear prior to reaching the peak strength which is about 16 kN for the tested bovine tibia. The full-field strain contours of the bone show that the strain distribution depends on not only the force direction, but also the natural bone shape. The natural arched-shape bovine tibia bone could bear a large force, due to the tissue structure with high strength, and the fracture propagation process of the sample initiates at the inner side of the bone first and propagates along the force direction.

  20. Analysis of mineral deposition in turkey tendons and self-assembled collagen fibers using mechanical techniques.

    Science.gov (United States)

    Freeman, Joseph W; Silver, Frederick H

    2004-01-01

    During limb movement and locomotion, animals store elastic energy in the tendons of the feet, legs, and other limbs. In the turkey, much of the force generated by the gastrocnemius muscle during locomotion is stored as elastic energy through deformation of the tendon. During growth and development, the leg tendons in some avians, including turkeys, mineralize and result in an increase in tensile strength and modulus. The purpose of our study was to evaluate the effects of mineralization on elastic energy storage and transmission in turkey tendons. Elastic and viscous stress-strain curves and elastic energy storage behavior were used to compare the behavior of mineralized turkey gastrocnemius tendons and mineralized self-assembled type I collagen fibers. Based on analysis of these two systems, we concluded that a simple mineralized fibrillar collagenous substrate can mimic the behavior of a more complex fibrillar collagenous substrate such as mineralized turkey tendon; however, the exact mechanism of mineralization may be different between the two substrates. Changes in mechanical properties of turkey tendon were consistent with a model in which mineralization appears to increase the effective collagen fibril length by efficiently transferring stress between neighboring collagen fibrils. Mineralization in self-assembled collagen fibers increased elastic energy storage less efficiently as compared with turkey tendon suggesting that the noncollagenous components of mineralizing tissue may act to promote collagen fibril to collagen fibril interactions.

  1. Impact of Packing and Processing Technique on Mechanical Properties of Acrylic Denture Base Materials

    Directory of Open Access Journals (Sweden)

    Touraj Nejatian

    2015-04-01

    Full Text Available The fracture resistance of polymethylmethacrylate (PMMA as the most popular denture base material is not satisfactory. Different factors can be involved in denture fracture. Among them, flexural fatigue and impact are the most common failure mechanisms of an acrylic denture base. It has been shown that there is a correlation between the static strength and fatigue life of composite resins. Therefore, the transverse strength of the denture base materials can be an important indicator of their service life. In order to improve the fracture resistance of PMMA, extensive studies have been carried out; however, only a few promising results were achieved, which are limited to some mechanical properties of PMMA at the cost of other properties. This study aimed at optimizing the packing and processing condition of heat-cured PMMA as a denture base resin in order to improve its biaxial flexural strength (BFS. The results showed that the plain type of resin with a powder/monomer ratio of 2.5:1 or less, packed conventionally and cured in a water bath for 2 h at 95 °C provides the highest BFS. Also, it was found that the performance of the dry heat processor is inconsistent with the number of flasks being loaded.

  2. A Survey on Optimal Signal Processing Techniques Applied to Improve the Performance of Mechanical Sensors in Automotive Applications

    Directory of Open Access Journals (Sweden)

    Wilmar Hernandez

    2007-01-01

    Full Text Available In this paper a survey on recent applications of optimal signal processing techniques to improve the performance of mechanical sensors is made. Here, a comparison between classical filters and optimal filters for automotive sensors is made, and the current state of the art of the application of robust and optimal control and signal processing techniques to the design of the intelligent (or smart sensors that today’s cars need is presented through several experimental results that show that the fusion of intelligent sensors and optimal signal processing techniques is the clear way to go. However, the switch between the traditional methods of designing automotive sensors and the new ones cannot be done overnight because there are some open research issues that have to be solved. This paper draws attention to one of the open research issues and tries to arouse researcher’s interest in the fusion of intelligent sensors and optimal signal processing techniques.

  3. [Binding mechanism of traditional Chinese medicine active component 5-hydroxymethyl-furfural and HSA or BSA].

    Science.gov (United States)

    Guo, Ming; He, Ling; Lu, Xiao-Wang

    2012-03-01

    A combination of spectral experiment and molecular modeling techniques has been used to characterize the binding mechanism between an active component 5-hydroxymethyl-furfural (5-HMF) of traditional Chinese medicine and human serum albumin (HSA) or bovine serum albumin (BSA). The interaction mechanism of 5-HMF binding with HSA/BSA is analyzed. Although the drug can bind with HSA/BSA to form stable complexes, there are some differences in the bond strength. The values of binding distances (r) are different and low, which indicated the occurrence of energy transfer. The drug had conformational effect on HSA/BSA, which resulted in different changes of hydrophobic environment of the binding domain in HSA/BSA. The 'phase diagram' of fluorescence revealed that the changes on the conformational pattern of proteins have been affected by drug conformed to the "all-or-none" pattern. The interactions between drug and protein influenced by Co(II) were also discussed. Its effects acting on 5-HMF-HSA/BSA interactions are different. The computational modeling method was used to study the interaction between 5-HMF and HSA/BSA. The results of molecular model studies revealed that the binding modes for drug-serum albumin systems are mainly hydrophobic interactions and hydrogen bonding. These results are in accordance with spectral results. The research results have given a better theoretical reference for the study of pharmacological mechanism of 5-hydroxymethyl-furfural.

  4. DNA mechanics as a tool to probe helicase and translocase activity.

    Science.gov (United States)

    Lionnet, Timothée; Dawid, Alexandre; Bigot, Sarah; Barre, François-Xavier; Saleh, Omar A; Heslot, François; Allemand, Jean-François; Bensimon, David; Croquette, Vincent

    2006-01-01

    Helicases and translocases are proteins that use the energy derived from ATP hydrolysis to move along or pump nucleic acid substrates. Single molecule manipulation has proved to be a powerful tool to investigate the mechanochemistry of these motors. Here we first describe the basic mechanical properties of DNA unraveled by single molecule manipulation techniques. Then we demonstrate how the knowledge of these properties has been used to design single molecule assays to address the enzymatic mechanisms of different translocases. We report on four single molecule manipulation systems addressing the mechanism of different helicases using specifically designed DNA substrates: UvrD enzyme activity detection on a stretched nicked DNA molecule, HCV NS3 helicase unwinding of a RNA hairpin under tension, the observation of RecBCD helicase/nuclease forward and backward motion, and T7 gp4 helicase mediated opening of a synthetic DNA replication fork. We then discuss experiments on two dsDNA translocases: the RuvAB motor studied on its natural substrate, the Holliday junction, and the chromosome-segregation motor FtsK, showing its unusual coupling to DNA supercoiling.

  5. Antimycobacterial Activity and Mechanism of Action of NAS-91.

    Science.gov (United States)

    Gratraud, Paul; Surolia, Namita; Besra, Gurdyal S; Surolia, Avadhesha; Kremer, Laurent

    2008-03-01

    The antimalarial agents NAS-91 and NAS-21 were found to express potent antimycobacterial activity, NAS-91 being more active than NAS-21. They partially inhibited mycolic acid biosynthesis and profoundly altered oleic acid production. The development of a cell-free assay for Delta 9-desaturase activity allowed direct demonstration of the inhibition of oleic acid biosynthesis by these compounds.

  6. Effects of nutrient intake on sympathoadrenal activity and thermogenic mechanisms

    DEFF Research Database (Denmark)

    Astrup, A V; Christensen, N J; Simonsen, L

    1990-01-01

    Ingestion of carbohydrate results in a diphasic activation of the sympathoadrenal system. One component is an insulin-mediated activation of the sympathetic nervous system (SNS). This activation is partly a haemodynamic reflex, but it may cause a weak thermogenic effect via beta 1-adrenoceptors i...

  7. [Techniques for measuring phakic and pseudophakic accommodation. Methodology for distinguishing between neurological and mechanical accommodative insufficiency].

    Science.gov (United States)

    Roche, O; Roumes, C; Parsa, C

    2007-11-01

    The methods available for studying accommodation are evaluated: Donder's "push-up" method, dynamic retinoscopy, infrared optometry using the Scheiner principle, and wavefront analysis are each discussed with their inherent advantages and limitations. Based on the methodology described, one can also distinguish between causes of accommodative insufficiency. Dioptric insufficiency (accommodative lag) that remains equal at various testing distances from the subject indicates a sensory/neurologic (afferent), defect, whereas accommodative insufficiency changing with distance indicates a mechanical/restrictive (efferent) defect, such as in presbyopia. Determining accommodative insufficiency and the cause can be particularly useful when examining patients with a variety of diseases associated with reduced accommodative ability (e.g., Down syndrome and cerebral palsy) as well as in evaluating the effectiveness of various potentially accommodating intraocular lens designs.

  8. Structural and mechanical properties of amorphous carbon films deposited by the dual plasma technique

    Institute of Scientific and Technical Information of China (English)

    Yaohui Wang; Xu Zhang; Xianying Wu; Huixing Zhang; Xiaoji Zhang

    2008-01-01

    Direct current metal filtered cathodic vacuum are (FCVA) and acetylene gas (C2H2) were wielded to synthesize Ti-containing amorphous carbon films on Si (100). The influence of substrate bias voltage and acetylene gas on the microstructure and mechanical properties of the films were investigated. The results show that the phase of TiC in the (111) preferential crystallo-graphic orientation exists in the film, and rite main existing pattern of carbon is sp2. With increasing the acetylene flow rate, the con-tents of Ti and TiC phase of the film gradually reduce; however, the thickness of the film increases. When the substrate bias voltage reaches -600 V, the internal stress of the film reaches 1.6 GPa. The micro-hardness and elastic modulus of the film can reach 33.9 and 237.6 GPa, respectively, and the friction coefficient of the film is 0.25.

  9. Evaluation of Antifungal Activity and Mechanism of Action of Citral against Candida albicans

    Directory of Open Access Journals (Sweden)

    Maria Clerya Alvino Leite

    2014-01-01

    Full Text Available Candida albicans is a yeast that commensally inhabits the human body and can cause opportunistic or pathogenic infections. Objective. To investigate the antifungal activity of citral against C. albicans. Methodology. The minimum inhibitory concentration (MIC and the minimum fungicidal concentration (MFC were determined by the broth microdilution techniques. We also investigated possible citral action on cell walls (0.8 M sorbitol, cell membranes (citral to ergosterol binding, the time-kill curve, and biological activity on the yeast’s morphology. Results. The MIC and MFC of citral were, respectively, 64 µg/mL and 256 µg/mL. Involvement with the cell wall and ergosterol binding were excluded as possible mechanisms of action. In the morphological interference assay, it was observed that the product inhibited pseudohyphae and chlamydoconidia formation. The MIC and the MFC of citral required only 4 hours of exposure to effectively kill 99.9% of the inoculum. Conclusion. Citral showed in vitro antifungal potential against strains of C. albicans. Citral’s mechanism of action does not involve the cell wall or ergosterol, and further study is needed to completely describe its effects before being used in the future as a component of new antifungals.

  10. Mechanical properties of nickel-titanium archwire used in the final treatment phase of Tip-Edge Plus technique: an in vitro study

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiao; SUN Xin-hua; TIAN Hua; ZHANG Chun-bo; YAN Kuo; GUO Yong-liang

    2013-01-01

    Background As the only active component in final treatment phase of Tip-Edge Plus technique,the activation of nickel-titanium orthodontic archwires is one of the factors that affect the torque expression.It is necessary to evaluate the mechanical properties of the nickel-titanium wire used in the final treatment phase in simulated oral environments to forecast the treatment outcomes.Methods The mechanical properties of 171 thermal nickel-titanium wires of 0.35 mm (0.014-in) in diameters with different deflection of 40 mm in length were investigated with three-point bending test.The samples were divided into 2 groups:as-received and bended groups.In the bended group,samples were divided into 7 subgroups according to the amounts of deflection and named by the canine angulations (-25°,-19°,-13°,-7°,-1°,+5°,+11°).The deflection of wires was made by inserting the wires into the deep tunnel of Tip-Edge Plus brackets positioned in plaster casts with different canine angulations to mimic the use of nickel-titanium wires in the final treatment phase.Immersed the bended group in artificial saliva (pH 6.8) and preserved at 37.0°C.Eight durations of incubation were tested:1 to 8 weeks.Three analogous samples of each group and subgroups were tested per week.Stiffness (YS:E) and the load-deflection characteristics of unloading plateau section were obtained.Results Significant changes in specific mechanical properties were observed in long-term immersed and large deflected wires compared with as-received groups.Both immersion time and deflection affected the mechanical properties of wires in the simulated oral environment,and the two factors had synergistic effect.In groups-25°,-19° and -13°,stiffness (YS:E) increased then decreased and average plateau force and ratio of variance decreased then increased correspondingly at specific time.Conclusions In the final treatment phase of Tip-Edge Plus technique,the mechanical properties of nickel-titanium wire are associated

  11. [Research activities in applied mathematics, fluid mechanics, and computer science

    Science.gov (United States)

    1995-01-01

    This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period April 1, 1995 through September 30, 1995.

  12. ArteFill permanent injectable for soft tissue augmentation: I. Mechanism of action and injection techniques.

    Science.gov (United States)

    Lemperle, Gottfried; Knapp, Terry R; Sadick, Neil S; Lemperle, Stefan M

    2010-06-01

    After more than 25 years of research and development, in October 2006 ArteFill became the first and only permanent injectable wrinkle filler to receive FDA approval. ArteFill is a third-generation polymeric microsphere-based filler, following its predecessor Artecoll, which was marketed outside the United States between 1994 and 2006. ArteFill is approved for the correction of nasolabial folds and has been used in over 15,000 patients since its U.S. market introduction in February 2007. No serious side effects have been reported to date according to the FDA's MAUDE reporting database. ArteFill consists of polymethylmethacrylate (PMMA) microspheres (20% by volume), 30-50 microm in diameter, suspended in 3.5% bovine collagen solution (80% by volume) and 0.3% lidocaine. The collagen carrier is absorbed within 1 month after injection and completely replaced by the patient's own connective tissue within 3 months. Each cc of ArteFill contains approximately six million microspheres and histological studies have shown that long-term wrinkle correction consists of 80% of the patient's own connective tissue and 20% microspheres. The standard injection technique is subdermal tunneling that delivers a strand of ArteFill at the dermal-subdermal junction. This strand beneath a wrinkle or fold acts like a support structure that protects against further wrinkling and allows the diminished thickness of the dermis to recover to its original thickness.

  13. Quantitation of microbicidal activity of mononuclear phagocytes: an in vitro technique.

    Directory of Open Access Journals (Sweden)

    Rege N

    1993-01-01

    Full Text Available An in vitro assay technique was set up to determine the phagocytic and microbicidal activity of a monocyte-macrophage cell line using Candida species as test organisms. The norms were determined for the activity of peritoneal macrophages of rats (24.69 +/- 2.6% phagocytosis and 35.4 +/- 5.22% ICK and human (27.89 +/- 3.63% phagocytosis and 50.91 +/- 6.3% ICK. The assay technique was used to test the degree of activation of macrophages induced by metronidazole, Tinospora cordifolia and Asparaqus racemousus and to compare their effects with a standard immunomodulator muramyl-dipeptide. All the three test agents increased the phagocytic and killing capacity of macrophages in a dose dependent manner upto a certain dose, beyond which either these activities were found to have plateaued or decreased. The optimal doses for MDP, Metronidazole, Asparagus racemosus and Tinospora cordifolia were found to be 100 micrograms, 300 mg/kg, 200 mg/kg and 100 mg/kg respectively. Patients with cirrhosis were screened for defects in monocyte function. The depressed monocyte function (20.58 +/- 5% phago and 41.24 +/- 12.19% ICK; P < 0.05 was observed indicating a compromised host defense. The utility of this candidicidal assay in experimental and clinical studies is discussed.

  14. A multi coding technique to reduce transition activity in VLSI circuits

    Science.gov (United States)

    Vithyalakshmi, N.; Rajaram, M.

    2014-02-01

    Advances in VLSI technology have enabled the implementation of complex digital circuits in a single chip, reducing system size and power consumption. In deep submicron low power CMOS VLSI design, the main cause of energy dissipation is charging and discharging of internal node capacitances due to transition activity. Transition activity is one of the major factors that also affect the dynamic power dissipation. This paper proposes power reduction analyzed through algorithm and logic circuit levels. In algorithm level the key aspect of reducing power dissipation is by minimizing transition activity and is achieved by introducing a data coding technique. So a novel multi coding technique is introduced to improve the efficiency of transition activity up to 52.3% on the bus lines, which will automatically reduce the dynamic power dissipation. In addition, 1 bit full adders are introduced in the Hamming distance estimator block, which reduces the device count. This coding method is implemented using Verilog HDL. The overall performance is analyzed by using Modelsim and Xilinx Tools. In total 38.2% power saving capability is achieved compared to other existing methods.

  15. Determination of moisture content and water activity in algae and fish by thermoanalytical techniques

    Directory of Open Access Journals (Sweden)

    Vilma Mota da Silva

    2008-01-01

    Full Text Available The water content in seafoods is very important since it affects their sensorial quality, microbiological stability, physical characteristics and shelf life. In this study, thermoanalytical techniques were employed to develop a simple and accurate method to determine water content (moisture by thermogravimetry (TG and water activity from moisture content values and freezing point depression using differential scanning calorimetry (DSC. The precision of the results suggests that TG is a suitable technique to determine moisture content in biological samples. The average water content values for fish samples of Lutjanus synagris and Ocyurus chrysurus species were 76.4 ± 5.7% and 63.3 ± 3.9%, respectively, while that of Ulva lactuca marine algae species was 76.0 ± 4.4%. The method presented here was also successfully applied to determine water activity in two species of fish and six species of marine algae collected in the Atlantic coastal waters of Bahia, in Brazil. Water activity determined in fish samples ranged from 0.946 - 0.960 and was consistent with values reported in the literature, i.e., 0.9 - 1.0. The water activity values determined in marine algae samples lay within the interval of 0.974 - 0.979.

  16. Determination of moisture content and water activity in algae and fish by thermoanalytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Vilma Mota da; Silva, Luciana Almeida; Andrade, Jailson B. de [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica]. E-mail: jailsong@ufba.br; Veloso, Marcia C. da Cunha [Centro Federal de Educacao Tecnologica da Bahia (CEFET-BA), Salvador, BA (Brazil)); Santos, Gislaine Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Biologia

    2008-07-01

    The water content in seafoods is very important since it affects their sensorial quality, microbiological stability, physical characteristics and shelf life. In this study, thermoanalytical techniques were employed to develop a simple and accurate method to determine water content (moisture) by thermogravimetry (TG) and water activity from moisture content values and freezing point depression using differential scanning calorimetry (DSC). The precision of the results suggests that TG is a suitable technique to determine moisture content in biological samples. The average water content values for fish samples of Lutjanus synagris and Ocyurus chrysurus species were 76.4 {+-} 5.7% and 63.3 {+-} 3.9%, respectively, while that of Ulva lactuca marine algae species was 76.0 {+-} 4.4%. The method presented here was also successfully applied to determine water activity in two species of fish and six species of marine algae collected in the Atlantic coastal waters of Bahia, in Brazil. Water activity determined in fish samples ranged from 0.946 - 0.960 and was consistent with values reported in the literature, i.e., 0.9 - 1.0. The water activity values determined in marine algae samples lay within the interval of 0.974 - 0.979. (author)

  17. Bond dissociation mechanism of ethanol during carbon nanotube synthesis via alcohol catalytic CVD technique: Ab initio molecular dynamics simulation

    Science.gov (United States)

    Oguri, Tomoya; Shimamura, Kohei; Shibuta, Yasushi; Shimojo, Fuyuki; Yamaguchi, Shu

    2014-03-01

    Dissociation of ethanol on a nickel cluster is investigated by ab initio molecular dynamics simulation to reveal the bond dissociation mechanism of carbon source molecules during carbon nanotube synthesis. C-C bonds in only CHxCO fragments are dissociated on the nickel cluster, whereas there is no preferential structure among the fragments for C-O bond dissociation. The dissociation preference is uncorrelated with the bond dissociation energy of corresponding bonds in freestanding molecules but is correlated with the energy difference between fragment molecules before and after dissociation on the nickel surface. Moreover, carbon-chain formation occurs after C-C bond dissociation in a continuous simulation. What determines the chirality of CNTs? What happens at the dissociation stage of carbon source molecules? Regarding the former question, many researchers have pointed out the good epitaxial relationship between a graphite network and a close-packed facet (i.e., fcc(1 1 1) or hcp(0 0 0 1)) of transition metals [17-19]. Therefore, the correlation between the chirality of CNTs and the angle of the step edge on metal (or metal carbide) surfaces has been closely investigated [20-22]. In association with this geometric matching, the epitaxial growth of graphene on Cu(1 1 1) and Ni(1 1 1) surfaces has recently been achieved via CCVD technique [23-25], which is a promising technique for the synthesis of large-area and monolayer graphene.Regarding the latter question, it is empirically known that the yield and quality of CNT products strongly depend on the choice of carbon source molecules and additives. For example, it is well known that the use of ethanol as carbon source molecules yields a large amount of SWNTs without amorphous carbons (called the alcohol CCVD (ACCVD) technique) compared with the CCVD process using hydrocarbons [4]. Moreover, the addition of a small amount of water dramatically enhances the activity and lifetime of the catalytic metal (called the

  18. Investigation of the solubility enhancement mechanism of rebaudioside D using a solid dispersion technique with potassium sorbate as a carrier.

    Science.gov (United States)

    Pang, Shintaro; Ma, Changchu; Zhang, Naijie; He, Lili

    2015-05-01

    Rebaudioside (Reb) D is a high intensity, natural sweetener that shows great potential for substituting sugar in sweetened beverages. However, Reb D is poorly water soluble, and thus, a solid dispersion technique was recently established to enhance its solubility. The purpose of this study was to elucidate the solubility enhancement mechanism of this solid dispersion material by employing Scanning Electron Microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR) and X-ray Diffraction (XRD). Potassium sorbate (KS) was chosen as the carrier and two different concentration ratios were investigated as solid dispersions (SD) and as physical mixtures (PM). Our data demonstrated the possible mechanism for enhancing solubility through solid dispersion through increased surface area/volume ratio and hydrogen bonding between Reb D and KS. The interaction between the two components were also related to the different concentration ratios, therefore an optimisation of the ratio is important to produce a soluble and stable complex.

  19. Mechanical properties of nanocrystalline metals, intermetalics and multiphase materials determined by tension, compression and disk-bend techniques

    Energy Technology Data Exchange (ETDEWEB)

    Eastman, J.A.; Thompson, L.J.; DiMelfi, R.J. [Argonne National Lab., IL (United States); Choudry, M. [Argonne National Lab., IL (United States)]/[Illinois Inst. of Tech., Chicago, IL (United States); Dollar, M. [Illinois Inst. of Tech., Chicago, IL (United States); Weertman, J.R. [Northwestern Univ., Evanston, IL (United States); Rittner, M.N.; Youngdahl, C.J. [Argonne National Lab., IL (United States)]/[Northwestern Univ., Evanston, IL (United States)

    1997-02-01

    The mechanical behavior of nanocrystalline metallic, intermetallic, and multiphase materials was investigated using tension, compression, and disk-bend techniques. Nanocrystalline NiAl, Al-Al{sub 3}Zr, and Cu were synthesized by gas condensation and either resistive or electron beam heating followed by high temperature vacuum compaction. Disk- bend tests of nanocrystalline NiAl show evidence of improved ductility at room temperature in this normally extremely brittle material. In contrast, tension tests of multiphase nanocrystalline Al- Al{sub 3}Zr samples show significant increases in strength by substantial reductions in ductility with decreasing grain size. Compression tests of nanocrystalline copper result in substantially higher yield stress and total elongation values than those measured in tensile tests. Implications for operative deformation mechanisms in these materials are discussed.

  20. Investigation of the coercivity mechanism for Nd-Fe-B based magnets prepared by a new technique of strip casting

    Institute of Scientific and Technical Information of China (English)

    LI Bo; HU Jifan; WANG Dongling; GUO Binglin; WANG Xinlin

    2004-01-01

    The coercivity mechanism of Nd-Fe-B based magnets prepared by a new technique of strip casting was investigated. Different from the traditional magnets, α-Fe phases are difficult to be found in Nd-Fe-B magnets prepared by strip casting. Meanwhile, the rich-Nd phases occur not only near the grain boundaries of main phases, but also within the main-phase grains. Investigation on the magnetizing field dependence of the coercivity for the (Nd0.935Dy0.065)14.5Fe79.4B6.1magnet and the temperature dependence of the coercivity for the Nd14.5Fe79.4B6.1magnet have been done. Results show that coercivities for strip casting magnets are controlled by the nucleation mechanism.

  1. Fault Severity Evaluation and Improvement Design for Mechanical Systems Using the Fault Injection Technique and Gini Concordance Measure

    Directory of Open Access Journals (Sweden)

    Jianing Wu

    2014-01-01

    Full Text Available A new fault injection and Gini concordance based method has been developed for fault severity analysis for multibody mechanical systems concerning their dynamic properties. The fault tree analysis (FTA is employed to roughly identify the faults needed to be considered. According to constitution of the mechanical system, the dynamic properties can be achieved by solving the equations that include many types of faults which are injected by using the fault injection technique. Then, the Gini concordance is used to measure the correspondence between the performance with faults and under normal operation thereby providing useful hints of severity ranking in subsystems for reliability design. One numerical example and a series of experiments are provided to illustrate the application of the new method. The results indicate that the proposed method can accurately model the faults and receive the correct information of fault severity. Some strategies are also proposed for reliability improvement of the spacecraft solar array.

  2. Characterisation of Al corrosion and its impact on the mechanical performance of composite cement wasteforms by the acoustic emission technique

    Science.gov (United States)

    Spasova, L. M.; Ojovan, M. I.

    2008-04-01

    In this study acoustic emission (AE) non-destructive method was used to evaluate the mechanical performance of cementitious wasteforms with encapsulated Al waste. AE waves generated as a result of Al corrosion in small-size blast furnace slag/ordinary Portland cement wasteforms were recorded and analysed. The basic principles of the conventional parameter-based AE approach and signal-based analysis were combined to establish a relationship between recorded AE signals and different interactions between the Al and the encapsulating cement matrix. The AE technique was shown as a potential and valuable tool for a new area of application related to monitoring and inspection of the mechanical stability of cementitious wasteforms with encapsulated metallic wastes such as Al.

  3. 78 FR 13057 - Agency Information Collection Activities; Information Collection; IT Dashboard Feedback Mechanism

    Science.gov (United States)

    2013-02-26

    ... ADMINISTRATION Agency Information Collection Activities; Information Collection; IT Dashboard Feedback Mechanism... to review and approve a previously approved information collection requirement regarding IT Dashboard... identified by Information Collection 3090- 0285, IT Dashboard Feedback Mechanism, by any of the following...

  4. Technique and experiment of active direct gas pressure measurement in coal roadway

    Energy Technology Data Exchange (ETDEWEB)

    Xue-xi Chen; Shang-quan Ma; Li-ming Qi [North China Institute of Science and Technology, Beijing (China). School of Safety Engineering

    2009-06-15

    An active measurement method and its principle was introduced considering the low success rate, special difficulty, and long measurement time of the direct gas pressure measurement currently used in coal roadways. The technology of drilling, borehole sealing depth, borehole sealing length, sealing control of the measuring process, compensatory computation of gas loss quantity and other key techniques were discussed. Finally, based on the latest instrument the authors developed, a series of experiments of direct gas pressure measurement in the coal roadways of the Jincheng and Tongchuan mine district, were carried out. The experimental results show that active gas pressure measurement technique has advantages as follows: (1) the application scope of direct gas pressure measurement technique is wide and it does not have the restriction of coal hardness, coal seam fissure and other conditions; (2) the measured results are credible, which can be tested by the same gas pressure value acquired from a different borehole in the same place; (3) the measurement process is convenient and quick, it takes about 2 to 3 days to acquire the gas pressure value in a coal seam. 8 refs., 1 fig., 2 tabs.

  5. Debris removal from artificial grooves using different endodontic irrigation activation techniques: ex vivo

    Directory of Open Access Journals (Sweden)

    Mügem Aslı Ekici

    2016-12-01

    Full Text Available Objective: The aim of this study was to compare the debris removal efficiency of different irrigation activation techniques from artificially formed endodontic grooves. Materials and Method: Crowns of twenty maxillary incisor teeth were removed and the root canals were prepared. Specimens were embedded in acrylic resin and placed into teflon molds. Acrylic resin blocks were removed from the molds and split longitudinally into equal two halves. A standardized artificial groove (4 mm x 0.2 mm x 0.5 mm was prepared at 2 mm distance from the apex and filled with dentinal debris. Acrylic resin blocks were placed into the teflon mold again and compressed. Four different irrigation activation techniques; Manual Dynamic Irrigation (MDI, Passive Ultrasonic Irrigation (PUI, Sonic Irrigation (SI and Apical Negative Pressure Irrigation (ANPI were used for debris removal. Conventional Irrigation (CI was applied as control. For standardization, each specimen was cleaned and reused (n=20. Before and after irrigation, images of the grooves were taken by using an operating microscope at x30 magnification. Amount of remaining debris was evaluated by using a scoring system. Data were analyzed by using Kruskall-Wallis and Mann-Whitney U tests (α=0.05. Results: There were statistically significant differences between the experimental groups (p0.05. Conclusion: PUI yielded the lowest debris scores. A simple and low-cost technique, MDI, yielded similar results with PUI.

  6. Technique and experiment of active direct gas pressure measurement in coal roadway

    Institute of Scientific and Technical Information of China (English)

    CHEN Xue-xi; MA Shang-quan; QI Li-ming

    2009-01-01

    An active measurement method and its principle was introduced considering the low success rate, special difficulty, and long measurement time of the direct gas pres-sure measurement currently used in coal roadways. The technology of drilling, borehole sealing depth, borehole sealing length, sealing control of the measuring process, com-pensatory computation of gas loss quantity and other key techniques were discussed. Fi-nally, based on the latest instrument the authors developed, a series of experiments of di-rect gas pressure measurement in the coal roadways of the Jincheng and Tongchuan mine district, were carried out. The experimental results show that active gas pressure measurement technique has advantages as follows: (1) the application scope of direct gas pressure measurement technique is wide and it does not have the restriction of coal hardness, coal seam fissure and other conditions; (2) the measured results are credible, which can be tested by the same gas pressure value acquired from a different borehole in the same place; (3) the measurement process is convenient and quick, it takes about 2 to 3 days to acquire the gas pressure value in a coal seam.

  7. Fluorous-assisted metal chelate affinity extraction technique for analysis of protein kinase activity.

    Science.gov (United States)

    Hayama, Tadashi; Kiyokawa, Ena; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2016-08-15

    We have developed a fluorous affinity-based extraction method for measurement of protein kinase activity. In this method, a fluorescent peptide substrate was phosphorylated by a protein kinase, and the obtained phosphopeptide was selectively captured with Fe(III)-immobilized perfluoroalkyliminodiacetic acid reagent via a metal chelate affinity technique. Next, the captured phosphopeptide was selectively extracted into a fluorous solvent mixture, tetradecafluorohexane and 1H,1H,2H,2H-tridecafluoro-1-n-octanol (3:1, v/v), using the specificity of fluorous affinity (fluorophilicity). In contrast, the remained substrate peptide in the aqueous (non-fluorous) phase was easily measured fluorimetrically. Finally, the enzyme activity could be assayed by measuring the decrease in fluorescence. The feasibility of this method was demonstrated by applying the method for measurement of the activity of cAMP-dependent protein kinase (PKA) using its substrate peptide (kemptide) pre-labeled with carboxytetramethylrhodamine (TAMRA).

  8. Hysteresis Current Control technique based on Space Vector Modulation for Active Power Filter

    Directory of Open Access Journals (Sweden)

    Wang Yun-liang

    2011-09-01

    Full Text Available In this paper, the hysteresis current control (HCC technique based on space vector modulation (SVM for shunt active power filter (APF is proposed. The switching control algorithms of the HCC based SVM manage to generate compensated current according to the reference current. Harmonics extraction is based on the instantaneous active and reactive power theorem in time domain by calculating the power compensation. A closed loop control system is carried out and the error current is the difference between the reference current which is obtained from the power compensation and the actual current needs to be injected back into the power grid. By implementing this control strategy, the APF manages to generate better compensated harmonics currents to the power grid. Keywords: active power filter, hysteresis current control, space vector modulation ,matlab/simulink

  9. Tools and techniques to study ligand-receptor interactions and receptor activation by TNF superfamily members.

    Science.gov (United States)

    Schneider, Pascal; Willen, Laure; Smulski, Cristian R

    2014-01-01

    Ligands and receptors of the TNF superfamily are therapeutically relevant targets in a wide range of human diseases. This chapter describes assays based on ELISA, immunoprecipitation, FACS, and reporter cell lines to monitor interactions of tagged receptors and ligands in both soluble and membrane-bound forms using unified detection techniques. A reporter cell assay that is sensitive to ligand oligomerization can identify ligands with high probability of being active on endogenous receptors. Several assays are also suitable to measure the activity of agonist or antagonist antibodies, or to detect interactions with proteoglycans. Finally, self-interaction of membrane-bound receptors can be evidenced using a FRET-based assay. This panel of methods provides a large degree of flexibility to address questions related to the specificity, activation, or inhibition of TNF-TNF receptor interactions in independent assay systems, but does not substitute for further tests in physiologically relevant conditions.

  10. Ultrafast studies of organometallic photochemistry: The mechanism of carbon-hydrogen bond activation in solution

    Energy Technology Data Exchange (ETDEWEB)

    Bromberg, S.E.

    1998-05-01

    When certain organometallic compounds are photoexcited in room temperature alkane solution, they are able to break or activate the C-H bonds of the solvent. Understanding this potentially practical reaction requires a detailed knowledge of the entire reaction mechanism. Because of the dynamic nature of chemical reactions, time-resolved spectroscopy is commonly employed to follow the important events that take place as reactants are converted to products. For the organometallic reactions examined here, the electronic/structural characteristics of the chemical systems along with the time scales for the key steps in the reaction make ultrafast UV/Vis and IR spectroscopy along with nanosecond Step-Scan FTIR spectroscopy the ideal techniques to use for this study. An initial study of the photophysics of (non-activating) model metal carbonyls centering on the photodissociation of M(CO){sub 6} (M = Cr, W, Mo) was carried out in alkane solutions using ultrafast IR spectroscopy. Next, picosecond UV/vis studies of the C-H bond activation reaction of Cp{sup *}M(CO){sub 2} (M = Rh, Ir), conducted in room temperature alkane solution, are described in an effort to investigate the origin of the low quantum yield for bond cleavage ({approximately}1%). To monitor the chemistry that takes place in the reaction after CO is lost, a system with higher quantum yield is required. The reaction of Tp{sup *}Rh(CO){sub 2} (Tp{sup *} = HB-Pz{sub 3}{sup *}, Pz{sup *} = 3,5-dimethylpyrazolyl) in alkanes has a quantum yield of {approximately}30%, making time resolved spectroscopic measurements possible. From ultrafast IR experiments, two subsequently formed intermediates were observed. The nature of these intermediates are discussed and the first comprehensive reaction mechanism for a photochemical C-H activating organometallic complex is presented.

  11. Elementary mechanics using Matlab a modern course combining analytical and numerical techniques

    CERN Document Server

    Malthe-Sørenssen, Anders

    2015-01-01

    This book – specifically developed as a novel textbook on elementary classical mechanics – shows how analytical and numerical methods can be seamlessly integrated to solve physics problems. This approach allows students to solve more advanced and applied problems at an earlier stage and equips them to deal with real-world examples well beyond the typical special cases treated in standard textbooks. Another advantage of this approach is that students are brought closer to the way physics is actually discovered and applied, as they are introduced right from the start to a more exploratory way of understanding phenomena and of developing their physical concepts. While not a requirement, it is advantageous for the reader to have some prior knowledge of scientific programming with a scripting-type language. This edition of the book uses Matlab, and a chapter devoted to the basics of scientific programming with Matlab is included. A parallel edition using Python instead of Matlab is also available. Last but not...

  12. Elementary mechanics using Python a modern course combining analytical and numerical techniques

    CERN Document Server

    Malthe-Sørenssen, Anders

    2015-01-01

    This book – specifically developed as a novel textbook on elementary classical mechanics – shows how analytical and numerical methods can be seamlessly integrated to solve physics problems. This approach allows students to solve more advanced and applied problems at an earlier stage and equips them to deal with real-world examples well beyond the typical special cases treated in standard textbooks. Another advantage of this approach is that students are brought closer to the way physics is actually discovered and applied, as they are introduced right from the start to a more exploratory way of understanding phenomena and of developing their physical concepts. While not a requirement, it is advantageous for the reader to have some prior knowledge of scientific programming with a scripting-type language. This edition of the book uses Python, and a chapter devoted to the basics of scientific programming with Python is included. A parallel edition using Matlab instead of Python is also available. Last but not...

  13. Assembly Test of Elastic Averaging Technique to Improve Mechanical Alignment for Accelerating Structure Assemblies in CLIC

    CERN Document Server

    Huopana, J

    2010-01-01

    The CLIC (Compact LInear Collider) is being studied at CERN as a potential multi-TeV e+e- collider [1]. The manufacturing and assembly tolerances for the required RF-components are important for the final efficiency and for the operation of CLIC. The proper function of an accelerating structure is very sensitive to errors in shape and location of the accelerating cavity. This causes considerable issues in the field of mechanical design and manufacturing. Currently the design of the accelerating structures is a disk design. Alternatively it is possible to create the accelerating assembly from quadrants, which favour the mass manufacturing. The functional shape inside of the accelerating structure remains the same and a single assembly uses less parts. The alignment of these quadrants has been previously made kinematic by using steel pins or spheres to align the pieces together. This method proved to be a quite tedious and time consuming method of assembly. To limit the number of different error sources, a meth...

  14. Mechanics of the ankle and subtalar joints revealed through a 3D quasi-static stress MRI technique.

    Science.gov (United States)

    Siegler, S; Udupa, J K; Ringleb, S I; Imhauser, C W; Hirsch, B E; Odhner, D; Saha, P K; Okereke, E; Roach, N

    2005-03-01

    A technique to study the three-dimensional (3D) mechanical characteristics of the ankle and of the subtalar joints in vivo and in vitro is described. The technique uses an MR scanner compatible 3D positioning and loading linkage to load the hindfoot with precise loads while the foot is being scanned. 3D image processing algorithms are used to derive from the acquired MR images bone morphology, hindfoot architecture, and joint kinematics. The technique was employed to study these properties both in vitro and in vivo. The ankle and subtler joint motion and the changes in architecture produced in response to an inversion load and an anterior drawer load were evaluated. The technique was shown to provide reliable measures of bone morphology. The left-to-right variations in bone morphology were less than 5%. The left-to-right variations in unloaded hindfoot architecture parameters were less than 10%, and these properties were only slightly affected by inversion and anterior drawer loads. Inversion and anterior drawer loads produced motion both at the ankle and at the subtalar joint. In addition, high degree of coupling, primarily of internal rotation with inversion, was observed both at the ankle and at the subtalar joint. The in vitro motion produced in response to inversion and anterior drawer load was greater than the in vivo motion. Finally, external motion, measured directly across the ankle complex, produced in response to load was much greater than the bone movements measured through the 3D stress MRI technique indicating the significant effect of soft tissue and skin interference.

  15. Training medical students in bag-valve-mask technique as an alternative to mechanical ventilation in a disaster surge setting.

    Science.gov (United States)

    Lin, Janet Y; Bhalla, Naina; King, Reneé A

    2009-01-01

    The objective of this study was to evaluate the rapid training of medical students and their ability to provide effective manual ventilation using the bag-valve-mask technique. A rapid training session highlighting essential aspects of the correct bag-valve-mask technique was given to 31 medical students. This was followed by a simulated experience with a certified respiratory therapist, monitored according to a checklist of essential bag-valve-mask (BVM) competency requirements. Pre-test and post-test surveys assessed the medical students' knowledge and ability to provide adequate BVM technique. Thirty-one students participated. Pre-survey results demonstrated a clear identification of the potential risk for a disaster (pandemic, natural, bioterrorist) with 55% of students responding that a definite risk did exist. Their usefulness in such an event also was ascertained with 55% of students replying they would assist with basic medical tasks, assist doctors, or assist with cardiopulmonary resuscitation. Post-survey results administered after a 30-minute didactic session on the basic features of resuscitation equipment and the essential components of BVM technique demonstrated that a majority of students knew the proper head positioning maneuvers in cases not involving trauma (93%) and in cases involving trauma (72%). All students completed and passed the competency checklist. Medical students can be rapidly trained and be utilized as a potential resource to carry out the potentially lifesaving task of manual ventilation using the BVM technique in a disaster situation in which the availability of mechanical ventilators and respiratory therapists may be limited.

  16. A new technique to improve the mechanical and biological performance of ultra high molecular weight polyethylene using a nylon coating.

    Science.gov (United States)

    Firouzi, Dariush; Youssef, Aya; Amer, Momen; Srouji, Rami; Amleh, Asma; Foucher, Daniel A; Bougherara, Habiba

    2014-04-01

    A new patent pending technique is proposed in this study to improve the mechanical and biological performance of ultra high molecular weight polyethylene (UHMWPE), i.e., to uniformly coat nylon onto the UHMWPE fiber (Firouzi et al., 2012). Mechanical tests were performed on neat and new nylon coated UHMWPE fibers to examine the tensile strength and creep resistance of the samples at different temperatures. Cytotoxicity and osteolysis induced by wear debris of the materials were investigated using (MTT) assay, and RT-PCR for tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) osteolysis markers. Mechanical test results showed substantial improvement in maximum creep time, maximum breaking force, and toughness values of Nylon 6,6 and Nylon 6,12 coated UHMWPE fibers between average 15% and 60% at 25, 50, and 70°C. Furthermore, cytotoxicity studies have demonstrated significant improvement in cell viability using the nylon coated UHMWPE over the neat one (72.4% vs 54.8%) for 48h and (80.7 vs 5%) for 72h (PNylon 6,6 coated UHMWPE (2.5 fold increase for TNFα at 48h, and three fold increase for IL-6 at 72h (Pnylon could be used as a novel material in clinical applications with lower cytotoxicity, less wear debris-induced osteolysis, and superior mechanical properties compared to neat UHMWPE.

  17. Glycyl radical activating enzymes: structure, mechanism, and substrate interactions.

    Science.gov (United States)

    Shisler, Krista A; Broderick, Joan B

    2014-03-15

    The glycyl radical enzyme activating enzymes (GRE-AEs) are a group of enzymes that belong to the radical S-adenosylmethionine (SAM) superfamily and utilize a [4Fe-4S] cluster and SAM to catalyze H-atom abstraction from their substrate proteins. GRE-AEs activate homodimeric proteins known as glycyl radical enzymes (GREs) through the production of a glycyl radical. After activation, these GREs catalyze diverse reactions through the production of their own substrate radicals. The GRE-AE pyruvate formate lyase activating enzyme (PFL-AE) is extensively characterized and has provided insights into the active site structure of radical SAM enzymes including GRE-AEs, illustrating the nature of the interactions with their corresponding substrate GREs and external electron donors. This review will highlight research on PFL-AE and will also discuss a few GREs and their respective activating enzymes. Copyright © 2014. Published by Elsevier Inc.

  18. Effects and Mechanisms of Mechanical Activation on Hydrogen Sorption/ Desorption of Nanoscale Lithium Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Leon, L.; Yang, Gary, Z.; Crosby, Kyle; Wwan, Xufei. Zhong, Yang; Markmaitree, Tippawan; Osborn, William; Hu, Jianzhi; Kwak, Ja Hun

    2012-04-26

    The objective of this project is to investigate and develop novel, mechanically activated, nanoscale Li3N-based and LiBH4-based materials that are able to store and release {approx}10 wt% hydrogen at temperatures near 100 C with a plateau hydrogen pressure of less than 10 bar. Four (4) material systems have been investigated in the course of this project in order to achieve the project objective. These 4 systems are (i) LiNH2+LiH, (ii) LiNH2+MgH2, (iii) LiBH4, and (iv) LiBH4+MgH2. The key findings we have obtained from these 4 systems are summarized below. *The thermodynamic driving forces for LiNH2+LiH and LiBH4 systems are not adequate to enable H2 release at temperatures < 100 C. *Hydrogen release in the solid state for all of the four systems is controlled by diffusion, and thus is a slow process. *LiNH2+MgH2 and LiBH4+MgH2 systems, although possessing proper thermodynamic driving forces to allow for H2 release at temperatures < 100 C, have sluggish reaction kinetics because of their diffusion-controlled rate-limiting steps. *Reducing particles to the nanometer length scale (< 50 nm) can improve the thermodynamic driving force to enable H2 release at near ambient temperature, while simultaneously enhancing the reaction kinetics as well as changing the diffusion-controlled rate-limiting step to gas desorption-controlled rate-limiting step. This phenomenon has been demonstrated with LiBH4 and offers the hope that further work along this direction will make one of the material systems, i.e., LiBH4, LiBH4+MgH2 and LiNH2+MgH2, possess the desired thermodynamic properties and rapid H2 uptake/release kinetics for on-board applications. Many of the findings and knowledge gained from this project have been published in archival refereed journal articles [1-15] and are accessible by general public. Thus, to avoid a bulky final report, the key findings and knowledge gained from this project will be succinctly summarized, particularly for those findings and knowledge

  19. A Novel (DDCC-SFG-Based Systematic Design Technique of Active Filters

    Directory of Open Access Journals (Sweden)

    M. Fakhfakh

    2013-09-01

    Full Text Available This paper proposes a novel idea for the synthesis of active filters that is based on the use of signal-flow graph (SFG stamps of differential difference current conveyors (DDCCs. On the basis of an RLC passive network or a filter symbolic transfer function, an equivalent SFG is constructed. DDCCs’ SFGs are identified inside the constructed ‘active’ graph, and thus the equivalent circuit can be easily synthesized. We show that the DDCC and its ‘derivatives’, i.e. differential voltage current conveyors and the conventional current conveyors, are the main basic building blocks in such design. The practicability of the proposed technique is showcased via three application examples. Spice simulations are given to show the viability of the proposed technique.

  20. Induced modifications on algae photosynthetic activity monitored by pump-and-probe technique

    Energy Technology Data Exchange (ETDEWEB)

    Barbini, R.; Colao, F.; Fantoni, R.; Palucci, A.; Ribezzo, S. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione; Tarzillo, G.; Carlozzi, P.; Pelosi, E. [CNR, Florence (Italy). Centro Studi Microorganismi Autotrofi

    1995-12-01

    The lidar fluorosensor system available at ENEA Frascati has been used for a series of laboratory measurements on brackish-water and marine phytoplankton grown in laboratory with the proper saline solution. The system, already used to measure the laser induced fluorescence spectra of different algae species and their detection limits, has been upgraded with a short pulse Nd:YAG laser and rearranged to test a new technique based on laser pump and probe excitation. Results of this new technique for remote monitoring of the in-vivo photosynthetic activity will be presented, as measured during a field campaign carried out in Florence during the Autumn 1993, where the effects of an actinic saturating light and different chemicals have also been checked.

  1. Monitoring of Landslide Activity in Slovakia Territory Using Multi-Temporal InSAR Techniques

    Science.gov (United States)

    Bakon, M.; Papco, J.; Perissin, D.; Lazecky, M.; Sousa, J. J.; Hlavacova, I.; Batorova, K.; Ondrejka, P.; Liscak, P.; Paudits, P.; Real, N.

    2015-05-01

    Slope deformations are the most important geohazards in Slovakia which annually cause an extensive economic damage of significant influence. About 22000 slope deformations have been registered so far, covering an area of almost 2600 km2 . Since 2010, 639 new slope failures have been witnessed and their activation was driven mainly by the climatic anomalies such as extraordinary rainfalls. Many of these landslides currently represent a direct threat to the lives, health and property of the residents in the affected areas. The landslide Nizna Mysla is considered to be the second most catastrophic landslide in the history of Slovakia. Damages to buildings and engineering networks had not been identified in the ‘90s of the last century when the first problems with the slope stability appeared. Up-to-now monitoring techniques has currently been reassessed to account for the results from satellite Synthetic Aperture Radar (SAR) techniques.

  2. Low activation brazing materials and techniques for SiC f/SiC composites

    Science.gov (United States)

    Riccardi, B.; Nannetti, C. A.; Petrisor, T.; Sacchetti, M.

    2002-12-01

    A low activation brazing technique for silicon carbide fiber reinforced silicon carbide matrix composites (SiC f/SiC) is presented; this technique is based on the use of the 78Si-22Ti (wt%) eutectic alloy. The joints obtained take advantage of a melting point able to avoid composite fibre-interface degradation. All the joints showed absence of discontinuities and defects at the interface and a fine eutectic structure. Moreover, the joint layer appeared well adherent both to the matrix and the fibre interphase and the brazing alloy infiltration looked sufficiently controlled. The joints of SiC f/SiC composites showed 71±10 MPa almost pure shear strength at RT and up to 70 MPa at 600 °C.

  3. Mechanical insufflation-exsufflation. Comparison of peak expiratory flows with manually assisted and unassisted coughing techniques.

    Science.gov (United States)

    Bach, J R

    1993-11-01

    Pulmonary complications are major causes of morbidity and mortality for patients with severe expiratory muscle weakness. The purpose of this study was to compare peak cough expiratory flows (PCEFs) during unassisted and assisted coughing and review the long-term use of mechanical insufflation-exsufflation (MI-E) for 46 neuromuscular ventilator users. These individuals used noninvasive methods of ventilatory support for a mean of 21.1 h/d for 17.3 +/- 15.5 years. They relied on manually assisted coughing and/or MI-E during periods of productive airway secretion. They reported a mean of 0.7 +/- 1.2 cases of pneumonia and other serious pulmonary complications and 2.8 +/- 5.6 hospitalizations during the 16.4-year period and no complications of MI-E. A sample of 21 of these patients with a mean forced vital capacity of 490 +/- 370 ml had a mean maximum insufflation capacity (MIC) achieved by a combination of air stacking of ventilator insufflations and glossopharyngeal breathing of 1,670 +/- 540 ml. The PCEFs for this sample were: following an unassisted inspiration, 1.81 +/- 1.03 L/s; following a MIC maneuver, 3.37 +/- 1.07 L/s; with manual assistance by abdominal compression following a MIC maneuver, 4.27 +/- 1.29 L/s; and with MI-E, 7.47 +/- 1.02 L/s. Each PCEF was significantly greater than the preceding, respectively (p < 0.01). We conclude that manually assisted coughing and MI-E are effective and safe methods for facilitating airway secretion clearance for neuromuscular ventilator users who would otherwise be managed by endotracheal suctioning. Severely decreased MIC, but not necessarily vital capacity, is an indication for tracheostomy.

  4. Study of the magnetospheres of active regions on the sun by radio astronomy techniques

    Science.gov (United States)

    Bogod, V. M.; Kal'tman, T. I.; Peterova, N. G.; Yasnov, L. V.

    2017-01-01

    In the 1990s, based on detailed studies of the structure of active regions (AR), the concept of the magnetosphere of the active region was proposed. This includes almost all known structures presented in the active region, ranging from the radio granulation up to noise storms, the radiation of which manifests on the radio waves. The magnetosphere concept, which, from a common point of view, considers the manifestations of the radio emission of the active region as a single active complex, allows one to shed light on the relation between stable and active processes and their interrelations. It is especially important to identify the basic ways of transforming nonthermal energy into thermal energy. A dominant role in all processes is attributed to the magnetic field, the measurement of which on the coronal levels can be performed by radio-astronomical techniques. The extension of the wavelength range and the introduction of new tools and advanced modeling capabilities makes it possible to analyze the physical properties of plasma structures in the AR magnetosphere and to evaluate the coronal magnetic fields at the levels of the chromosphere-corona transition zone and the lower corona. The features and characteristics of the transition region from the S component to the B component have been estimated.

  5. Effects of Cobalt on the Sintering Behavior of Mechanically Activated Tungsten Powder

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Tungsten alloys were prepared with mechanically activated powder added microelement cobalt in order to improve the process and properties of alloys. Properties of alloys such as density, hardness and bending strength were measured. The results show that through mechanical activation, cobalt can accelerate the sintering process of these alloys. By the combination of mechanical activation and adding microelement cobalt, tungsten alloys with higher density and better properties can be obtained.

  6. Aluminum alloy weldability. Identification of weld solidification cracking mechanisms through novel experimental technique and model development

    Energy Technology Data Exchange (ETDEWEB)

    Coniglio, Nicolas

    2008-07-01

    The objective of the present thesis is to make advancements in understanding solidification crack formation in aluminum welds, by investigating in particular the aluminum 6060/4043 system. Alloy 6060 is typical of a family of Al-Mg-Si extrusion alloys, which are considered weldable only when using an appropriate filler alloy such as 4043 (Al-5Si). The effect of 4043 filler dilution (i.e. weld metal silicon content) on cracking sensitivity and solidification path of Alloy 6060 welds are investigated. Afterwards, cracking models are developed to propose mechanisms for solidification crack initiation and growth. Cracking Sensitivity. Building upon the concept that silicon improves weldability and that weldability can be defined by a critical strain rate, strain rate-composition combinations required for solidification crack formation in the Al- 6060/4043 system were determined using the newly developed Controlled Tensile Weldability (CTW) test utilizing local strain extensometer measurements. Results, presented in a critical strain rate - dilution map, show a crack - no crack boundary which reveals that higher local strain rates require higher 4043 filler dilution to avoid solidification cracking when arc welding Alloy 6060. Using the established crack - no crack boundary as a line of reference, additional parameters were examined and their influence on cracking characterized. These parameter influences have included studies of weld travel speed, weld pool contaminants (Fe, O, and H), and grain refiner additions (TiAl{sub 3} + Boron). Each parameter has been independently varied and its effect on cracking susceptibility quantified in terms of strain rate - composition combinations. Solidification Path. Solidification path of the Al-6060/4043 system was characterized using thermal analysis and phase identification. Increasing 4043 filler dilution from 0 to 16% in Alloy 6060 arc welds resulted in little effect on thermal arrests and microstructure, no effect on

  7. Cellular Mechanisms of Calcium-Mediated Triggered Activity

    Science.gov (United States)

    Song, Zhen

    Life-threatening cardiac arrhythmias continue to pose a major health problem. Ventricular fibrillation, which is a complex form of electrical wave turbulence in the lower chambers of the heart, stops the heart from pumping and is the largest cause of natural death in the United States. Atrial fibrillation, a related form of wave turbulence in the upper heart chambers, is in turn the most common arrhythmia diagnosed in clinical practice. Despite extensive research to date, mechanisms of cardiac arrhythmias remain poorly understood. It is well established that both spatial disorder of the refractory period of heart cells and triggered activity (TA) jointly contribute to the initiation and maintenance of arrhythmias. TA broadly refers to the abnormal generation of a single or a sequence of abnormal excitation waves from a small submillimeter region of the heart in the interval of time between two normal waves generated by the heart's natural pacemaker (the sinoatrial node). TA has been widely investigated experimentally and occurs in several pathological conditions where the intracellular concentration of free Ca2+ ions in heart cells becomes elevated. Under such conditions, Ca2+ can be spontaneously released from intracellular stores, thereby driving an electrogenic current that exchanges 3Na+ ions for one Ca2+ ion across the cell membrane. This current in turn depolarizes the membrane of heart cells after a normal excitation. If this calcium-mediated "delayed after depolarization'' (DAD) is sufficiently large, it can generate an action potential. While the arrhythmogenic importance of spontaneous Ca2+ release and DADs is well appreciated, the conditions under which they occur in heart pathologies remain poorly understood. Calcium overload is only one factor among several other factors that can promote DADs, including sympathetic nerve stimulation, different expression levels of membrane ion channels and calcium handling proteins, and different mutations of those

  8. Comparison of Selective Culturing and Biochemical Techniques for Measuring Biological Activity in Geothermal Process Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Pryfogle, Peter Albert

    2000-09-01

    For the past three years, scientists at the Idaho National Engineering and Environmental Laboratory have been conducting studies aimed at determining the presence and influence of bacteria found in geothermal plant cooling water systems. In particular, the efforts have been directed at understanding the conditions that lead to the growth and accumulation of biomass within these systems, reducing the operational and thermal efficiency. Initially, the methods selected were based upon the current practices used by the industry and included the collection of water quality parameters, the measurement of soluble carbon, and the use of selective medial for the determination of the number density of various types of organisms. This data has been collected on a seasonal basis at six different facilities located at the Geysers’ in Northern California. While this data is valuable in establishing biological growth trends in the facilities and providing an initial determination of upset or off-normal conditions, more detailed information about the biological activity is needed to determine what is triggering or sustaining the growth in these facilities in order to develop improved monitoring and treatment techniques. In recent years, new biochemical approaches, based upon the analyses of phospholipid fatty acids and DNA recovered from environmental samples, have been developed and commercialized. These techniques, in addition to allowing the determination of the quantity of biomass, also provide information on the community composition and the nutritional status of the organisms. During the past year, samples collected from the condenser effluents of four of the plants from The Geysers’ were analyzed using these methods and compared with the results obtained from selective culturing techniques. The purpose of this effort was to evaluate the cost-benefit of implementing these techniques for tracking microbial activity in the plant study, in place of the selective culturing

  9. Benefits of detailed models of muscle activation and mechanics

    Science.gov (United States)

    Lehman, S. L.; Stark, L.

    1981-01-01

    Recent biophysical and physiological studies identified some of the detailed mechanisms involved in excitation-contraction coupling, muscle contraction, and deactivation. Mathematical models incorporating these mechanisms allow independent estimates of key parameters, direct interplay between basic muscle research and the study of motor control, and realistic model behaviors, some of which are not accessible to previous, simpler, models. The existence of previously unmodeled behaviors has important implications for strategies of motor control and identification of neural signals. New developments in the analysis of differential equations make the more detailed models feasible for simulation in realistic experimental situations.

  10. Landing Technique Improvements After an Aquatic-Based Neuromuscular Training Program in Physically Active Women.

    Science.gov (United States)

    Scarneo, Samantha E; Root, Hayley J; Martinez, Jessica C; Denegar, Craig; Casa, Douglas J; Mazerolle, Stephanie M; Dann, Catie L; Aerni, Giselle A; DiStefano, Lindsay J

    2017-01-01

    Neuromuscular training programs (NTPs) improve landing technique and decrease vertical ground-reaction forces (VGRFs), resulting in injury-risk reduction. NTPs in an aquatic environment may elicit the same improvements as land-based programs with reduced joint stress. To examine the effects of an aquatic NTP on landing technique as measured by the Landing Error Scoring System (LESS) and VGRFs, immediately and 4 mo after the intervention. Repeated measures, pool and laboratory. Fifteen healthy, recreationally active women (age 21 ± 2 y, mass 62.02 ± 8.18 kg, height 164.74 ± 5.97 cm) who demonstrated poor landing technique (LESS-Real Time > 4). All participants completed an aquatic NTP 3 times/wk for 6 wk. Participants' landing technique was evaluated using a jump-landing task immediately before (PRE), immediately after (POST), and 4 mo after (RET) the intervention period. A single rater, blinded to time point, graded all videos using the LESS, which is a valid and reliable movement-screening tool. Peak VGRFs were measured during the stance phase of the jump-landing test. Repeated-measure analyses of variance with planned comparisons were performed to explore differences between time points. LESS scores were lower at POST (4.46 ± 1.69 errors) and at RET (4.2 ± 1.72 errors) than at PRE (6.30 ± 1.78 errors) (P .05). Participants also landed with significantly lower peak VGRFs (P aquatic NTP improves landing technique and suggest that improvements are retained over time. These results show promise of using an aquatic NTP when there is a desire to reduce joint loading, such as early stages of rehabilitation, to improve biomechanics and reduce injury risk.

  11. Collaborative mechanisms for a new perspective on active ageing

    NARCIS (Netherlands)

    Camarinha-Matos, L.M.; Afsarmanesh, H.

    2009-01-01

    The collaborative networks paradigm, supported by advanced community building and collaboration ICT platforms, can provide a new approach to active ageing. This paper introduces first results of a road mapping initiative towards the elaboration of a new vision for extending professional active life.

  12. Collaborative mechanisms for a new perspective on active ageing

    NARCIS (Netherlands)

    Camarinha-Matos, L.M.; Afsarmanesh, H.

    2009-01-01

    The collaborative networks paradigm, supported by advanced community building and collaboration ICT platforms, can provide a new approach to active ageing. This paper introduces first results of a road mapping initiative towards the elaboration of a new vision for extending professional active life.

  13. Effects of Active and Passive Control Techniques on Mach 1.5 Cavity Flow Dynamics

    Directory of Open Access Journals (Sweden)

    Selin Aradag

    2017-01-01

    Full Text Available Supersonic flow over cavities has been of interest since 1960s because cavities represent the bomb bays of aircraft. The flow is transient, turbulent, and complicated. Pressure fluctuations inside the cavity can impede successful weapon release. The objective of this study is to use active and passive control methods on supersonic cavity flow numerically to decrease or eliminate pressure oscillations. Jet blowing at several locations on the front and aft walls of the cavity configuration is used as an active control method. Several techniques are used for passive control including using a cover plate to separate the flow dynamics inside and outside of the cavity, trailing edge wall modifications, such as inclination of the trailing edge, and providing curvature to the trailing edge wall. The results of active and passive control techniques are compared with the baseline case in terms of pressure fluctuations, sound pressure levels at the leading edge, trailing edge walls, and cavity floor and in terms of formation of the flow structures and the results are presented. It is observed from the results that modification of the trailing edge wall is the most effective of the control methods tested leading to up to 40 dB reductions in cavity tones.

  14. Probability-Based Diagnostic Imaging Technique Using Error Functions for Active Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    Rahim Gorgin,

    2014-07-01

    Full Text Available This study presents a novel probability-based diagnostic imaging (PDI technique using error functions for active structural health monitoring (SHM. To achieve this, first the changes between baseline and current signals of each sensing path are measured, and by taking the root mean square of such changes, the energy of the scattered signal at different times can be calculated. Then, for different pairs of signal acquisition paths, an error function based on the energy of the scattered signals is introduced. Finally, the resultant error function is fused to the final estimation of the probability of damage presence in the monitoring area. As for applications, developed methods were employed to various damage identification cases, including cracks located in regions among an active sensor network with different configurations (pulse-echo and pitch-catch, and holes located in regions outside active network sensors with pitch-catch configuration. The results identified using experimental Lamb wave signals at different central frequencies corroborated that the developed PDI technique using error functions is capable of monitoring structural damage, regardless of its shape, size and location. The developed method doesn’t need direct interpretation of overlaid and dispersed lamb wave components for damage identification and can monitor damage located anywhere in the structure. These bright advantages, qualify the above presented PDI method for online structural health monitoring.

  15. Designed nanostructured pt film for electrocatalytic activities by underpotential deposition combined chemical replacement techniques.

    Science.gov (United States)

    Huang, Minghua; Jin, Yongdong; Jiang, Heqing; Sun, Xuping; Chen, Hongjun; Liu, Baifeng; Wang, Erkang; Dong, Shaojun

    2005-08-18

    Multiple-deposited Pt overlayer modified Pt nanoparticle (MD-Pt overlayer/PtNPs) films were deliberately constructed on glassy carbon electrodes through alternately multiple underpotential deposition (UPD) of Ag followed redox replacement reaction by Pt (II) cations. The linear and regular growth of the films characterized by cyclic voltammetry was observed. Atomic force spectroscopy (AFM) provides the surface morphology of the nanostructured Pt films. Rotating disk electrode (RDE) voltammetry and rotating ring-disk electrode (RRDE) voltammetry demonstrate that the MD-Pt overlayer/PtNPs films can catalyze an almost four-electron reduction of O(2) to H(2)O in air-saturated 0.1 M H(2)SO(4). Thus-prepared Pt films behave as novel nanostructured electrocatalysts for dioxygen reduction and hydrogen evolution reaction (HER) with enhanced electrocatalytic activities, in terms of both reduction peak potential and peak current, when compared to that of the bulk polycrystalline Pt electrode. Additionally, it is noted that after multiple replacement cycles, the electrocatalytic activities improved remarkably, although the increased amount of Pt is very low in comparison to that of pre-modified PtNPs due to the intrinsic feature of the UPD-redox replacement technique. In other words, the electrocatalytic activities could be improved markedly without using very much Pt by the technique of tailoring the catalytic surface. These features may provide an interesting way to produce Pt catalysts with a reliable catalytic performance as well as a reduction in cost.

  16. Effect of Extraction Solvent/Technique on the Antioxidant Activity of Selected Medicinal Plant Extracts

    Directory of Open Access Journals (Sweden)

    Bushra Sultana

    2009-06-01

    Full Text Available Theeffects of four extracting solvents [absolute ethanol, absolute methanol, aqueous ethanol (ethanol: water, 80:20 v/v and aqueous methanol (methanol: water, 80:20 v/v] and two extraction techniques (shaking and reflux on the antioxidant activity of extracts of barks of Azadirachta indica, Acacia nilotica, Eugenia jambolana, Terminalia arjuna, leaves and roots of Moringa oleifera, fruit of Ficus religiosa,and leaves of Aloe barbadensis were investigated. The tested plant materials contained appreciable amounts of total phenolic contents (0.31-16.5 g GAE /100g DW, total flavonoid (2.63-8.66 g CE/100g DW; reducing power at 10 mg/mL extract concentration (1.36-2.91, DPPH. scavenging capacity (37.2-86.6%, and percent inhibition of linoleic acid (66.0-90.6%. Generally higher extract yields, phenolic contents and plant material antioxidant activity were obtained using aqueous organic solvents, as compared to the respective absolute organic solvents. Although higher extract yields were obtained by the refluxing extraction technique, in general higher amounts of total phenolic contents and better antioxidant activity were found in the extracts prepared using a shaker.

  17. The effects of communication techniques on public relation activities: A sample of hospitality business

    Directory of Open Access Journals (Sweden)

    Şirvan Şen Demir

    2011-07-01

    Full Text Available Nowadays, firms who give importance to public relations have been increasing rapidly in numbers. All modern firms either found public relations department in their body to deal with public relations operations or outsource this activity to consultants in order to communicate with target populations. Among the firms in tourism sector, hospitality companies are the ones that use public relations the most. The purpose of this study is to investigate the communication techniques in public relation and effects of these techniques on public relation activities. A literature review was conducted for research model and then questionnaire was developed from the studies in the literature. Data were collected by researchers in face-to-face interviews with 145 supervisors who are responsible for public relation activities of the hotel and were analyzed with SPSS statistical programs. Structural and convergent validity of the data have revealed with the explanatory factor analysis. It was tested using a regression analysis to determine the effects of independent variables on dependent variables. As a result, independent variables have positive effects on the dependent variables.

  18. Mechanical Elongation of the Small Intestine: Evaluation of Techniques for Optimal Screw Placement in a Rodent Model

    Directory of Open Access Journals (Sweden)

    P. A. Hausbrandt

    2013-01-01

    Full Text Available Introduction. The aim of this study was to evaluate techniques and establish an optimal method for mechanical elongation of small intestine (MESI using screws in a rodent model in order to develop a potential therapy for short bowel syndrome (SBS. Material and Methods. Adult female Sprague Dawley rats (n=24 with body weight from 250 to 300 g (Σ=283 were evaluated using 5 different groups in which the basic denominator for the technique involved the fixation of a blind loop of the intestine on the abdominal wall with the placement of a screw in the lumen secured to the abdominal wall. Results. In all groups with accessible screws, the rodents removed the implants despite the use of washers or suits to prevent removal. Subcutaneous placement of the screw combined with antibiotic treatment and dietary modifications was finally successful. In two animals autologous transplantation of the lengthened intestinal segment was successful. Discussion. While the rodent model may provide useful basic information on mechanical intestinal lengthening, further investigations should be performed in larger animals to make use of the translational nature of MESI in human SBS treatment.

  19. Office-Based Elastographic Technique for Quantifying Mechanical Properties of Skeletal Muscle

    Science.gov (United States)

    Ballyns, Jeffrey J.; Turo, Diego; Otto, Paul; Shah, Jay P.; Hammond, Jennifer; Gebreab, Tadesse; Gerber, Lynn H.; Sikdar, Siddhartha

    2012-01-01

    Objectives Our objectives were to develop a new, efficient, and easy-to-administer approach to ultrasound elastography and assess its ability to provide quantitative characterization of viscoelastic properties of skeletal muscle in an outpatient clinical environment. We sought to show its validity and clinical utility in assessing myofascial trigger points, which are associated with myofascial pain syndrome. Methods Ultrasound imaging was performed while the muscle was externally vibrated at frequencies in the range of 60 to 200 Hz using a handheld vibrator. The spatial gradient of the vibration phase yielded the shear wave speed, which is related to the viscoelastic properties of tissue. The method was validated using a calibrated experimental phantom, the biceps brachii muscle in healthy volunteers (n = 6), and the upper trapezius muscle in symptomatic patients with axial neck pain (n = 13) and asymptomatic (pain-free) control participants (n = 9). Results Using the experimental phantom, our method was able to quantitatively measure the shear moduli with error rates of less than 20%. The mean shear modulus ± SD in the normal biceps brachii measured 12.5 ± 3.4 kPa, within the range of published values using more sophisticated methods. Shear wave speeds in active myofascial trigger points and the surrounding muscle tissue were significantly higher than those in normal tissue at high frequency excitations (>100 Hz; P myofascial trigger points have increased tissue heterogeneity at the trigger point site and the surrounding muscle tissue. PMID:22837285

  20. Mechanism of Metal Ion Activation of the Diphtheria Toxin Repressor DtxR

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino,J.; Tetenbaum-Novatt, J.; White, A.; Berkovitch, F.; Ringe, D.

    2005-01-01

    The diphtheria toxin repressor (DtxR) is a metal ion-activated transcriptional regulator that has been linked to the virulence of Corynebacterium diphtheriae. Structure determination has shown that there are two metal ion binding sites per repressor monomer, and site-directed mutagenesis has demonstrated that binding site 2 (primary) is essential for recognition of the target DNA repressor, leaving the role of binding site 1 (ancillary) unclear. Calorimetric techniques have demonstrated that although binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 x 10{sup -7}, binding site 2 (primary) is a low-affinity binding site with a binding constant of 6.3 x 10{sup -4}. These two binding sites act in an independent fashion, and their contribution can be easily dissected by traditional mutational analysis. Our results clearly demonstrate that binding site 1 (ancillary) is the first one to be occupied during metal ion activation, playing a critical role in stabilization of the repressor. In addition, structural data obtained for the mutants Ni-DtxR(H79A, C102D), reported here, and the previously reported DtxR(H79A) have allowed us to propose a mechanism of metal activation for DtxR.

  1. 机械化节水灌溉技术探讨%Discussion on Mechanized Water-saving Irrigation Techniques

    Institute of Scientific and Technical Information of China (English)

    胡艳清; 孙号茗; 田树良

    2012-01-01

    This article deals with the definition, advantages and drawbacks of such mechanized water saving irrigation techniques as sprinkling irrigation, micro-irrigation and walking water-saving irrigation, and describes the technical characteristics and applicabiIity in the application process of these various water-saving techniques in a bid to provide reference for the promotion and application of mech- anized water-saving irrigation techniques.%为缓解我国水资源短缺的情况,介绍喷灌机械化技术、微灌机械化技术和行走节水灌溉机械化技术的定义及优缺点.阐述各项节水技术在应用过程中的技术特点及适用性,为推广应用机械化节水灌溉技术提供参考。

  2. Mechanically durable, superomniphobic coatings prepared by layer-by-layer technique for self-cleaning and anti-smudge.

    Science.gov (United States)

    Brown, Philip S; Bhushan, Bharat

    2015-10-15

    Superomniphobic surfaces are of interest for anti-fouling, self-cleaning, anti-smudge and low-drag applications. Many bioinspired surfaces developed previously are of limited use due to a lack of mechanical durability. From a previously developed technique, an adapted layer-by-layer approach involving charged species with electrostatic interactions between layers is combined with an uncharged fluorosilane layer to result in a durable, superomniphobic coating. This technique can provide the flexibility needed to improve adhesion to the substrate with the addition of a low surface tension coating at the air interface. In this work, polyelectrolyte binder, SiO2 nanoparticles, and fluorosilane layers are deposited, providing the combination of surface roughness and low surface tension to result in a superomniphobic coating with droplets of liquids with surface tensions from 72 to 21 mN m(-1) displaying contact angles exceeding 155° with low tilt angles. The durability of these coatings was examined through the use of micro- and macrowear experiments. These coatings currently display levels of transparency acceptable for automotive applications. Fabrication via this novel combination of techniques results in durable, superomniphobic coatings displaying improved performance compared to existing work where either the durability or the repellency is compromised.

  3. System of mechanisms for strategic planning of innovation activity

    Directory of Open Access Journals (Sweden)

    A. V. Seryakov

    2013-01-01

    Full Text Available The paper addresses the need for mechanisms of planning software innovation. Feature of the system is that that the system is the evaluation of the problems of defense production and to ensure the necessary flexibility in their decision by taking into account international standards and correction of the high-tech systems.

  4. CCN Spectra Measurements as an Active Tracer of Stratocumulus Mechanisms

    Science.gov (United States)

    1992-01-01

    mechanisms outlined here are very important in the global cycle of CCN. Comparisons of the CCN spectra with cut sizes used in the counterflow virtual...penetrations. The CVI is a discriminating sampler which allows only particles above certain cut sizes to enter; smaller cloud droplets and interstitial

  5. Compensating for Bias in the SDM Fast Activation Mechanism

    OpenAIRE

    Karlsson, Roland

    1996-01-01

    The Kanerva Sparse Distributed Memory (SDM) is a mechanism for implementing a memory with a huge address space. The physical memory consists of substantially fewer locations than the virtual address space. The plain Kanerva SDM memory assumes address and data to be random bit vectors with equal probability for 0 and 1. To compensate for any bias in address or data, several more or ...

  6. Active noise canceling system for mechanically cooled germanium radiation detectors

    Science.gov (United States)

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  7. Influence of Activated Carbon Particles on Intermetallic Compound Growth Mechanism in Sn-Cu-Ni Composite Solder

    Directory of Open Access Journals (Sweden)

    Ramli M.I.I.

    2016-01-01

    Full Text Available The influence of Activated Carbon (AC particles on mechanical properties of Sn-Cu-Ni-xAC solder joint was investigated. Five different Activated Carbon (AC percentage addition (0 wt. %, 0.25 wt. %, 0.5 wt. %, 0.75 wt. %, and 1.0 wt. % were prepared via powder metallurgy (PM technique. Interfacial IMC thickness measurement and shear strength results showed that with thinner IMC layer (by increasing amount of wt.% of AC, the higher the shear strength of the joint. It is believed that the AC particles suppresses the interfacial IMC growth and thus improves the shear strength.

  8. Low-Shapiro hydrostatic reconstruction technique for blood flow simulation in large arteries with varying geometrical and mechanical properties

    Science.gov (United States)

    Ghigo, A. R.; Delestre, O.; Fullana, J.-M.; Lagrée, P.-Y.

    2017-02-01

    The purpose of this work is to construct a simple, efficient and accurate well-balanced numerical scheme for one-dimensional (1D) blood flow in large arteries with varying geometrical and mechanical properties. As the steady states at rest are not relevant for blood flow, we construct two well-balanced hydrostatic reconstruction techniques designed to preserve low-Shapiro number steady states that may occur in large network simulations. The Shapiro number Sh = u / c is the equivalent of the Froude number for shallow water equations and the Mach number for compressible Euler equations. The first is the low-Shapiro hydrostatic reconstruction (HR-LS), which is a simple and efficient method, inspired from the hydrostatic reconstruction technique (HR). The second is the subsonic hydrostatic reconstruction (HR-S), adapted here to blood flow and designed to exactly preserve all subcritical steady states. We systematically compare HR, HR-LS and HR-S in a series of single artery and arterial network numerical tests designed to evaluate their well-balanced and wave-capturing properties. The results indicate that HR is not adapted to compute blood flow in large arteries as it is unable to capture wave reflections and transmissions when large variations of the arteries' geometrical and mechanical properties are considered. On the contrary, HR-S is exactly well-balanced and is the most accurate hydrostatic reconstruction technique. However, HR-LS is able to compute low-Shapiro number steady states as well as wave reflections and transmissions with satisfying accuracy and is simpler and computationally less expensive than HR-S. We therefore recommend using HR-LS for 1D blood flow simulations in large arterial network simulations.

  9. Active load sharing technique for on-line efficiency optimization in DC microgrids

    DEFF Research Database (Denmark)

    Sanseverino, E. Riva; Zizzo, G.; Boscaino, V.

    2017-01-01

    , is created to store the real efficiencies of the converters taking into account components tolerances. A MATLAB/Simulink model of the DC distribution network has been set up and a Genetic Algorithm has been employed for the global efficiency optimization. Simulation results are shown to validate the proposed......-DC converters, is modeled. An active load sharing technique is proposed for the on-line optimization of the global efficiency of the DC distribution network. The algorithm aims at the instantaneous efficiency optimization of the whole DC network, based on the on-line load current sampling. A Look Up Table...

  10. The use of selected theatre rehearsal technique activities with African-American adolescents labeled "behavior disordered".

    Science.gov (United States)

    Anderson, M G

    1992-01-01

    The extensive literature on the overrepresentation of adolescent African-American male learners in classes for students identified as behavior disordered has essentially not addressed the problems caused by teacher reactions to adolescent conversational language use, the qualitative differences in language choices, or the impact of the conversational choices of adolescents on their educational treatment. This article explores how the dramaturgical perspective of selected Theatre Rehearsal Technique (TRT) activities can be used as learning experiences in communication with this student population. If these students gain quantifiable success in their social communication interactions, reassessment of their special education placement might facilitate their entrance into less restrictive educational environments.

  11. Nonthermal Fluctuations and Mechanics of the Active Cell Nucleus

    CERN Document Server

    Smith, K; Byrd, H; MacKintosh, F C; Kilfoil, M L

    2013-01-01

    We present direct measurements of fluctuations in the nucleus of yeast cells. While prior work has shown these fluctuations to be active and non-thermal in character, their origin and time dependence are not understood. We show that nuclear fluctuations can be quantitatively understood by uncorrelated, active force fluctuations driving a nuclear medium that is dominated by an uncondensed DNA solution, for which we perform rheological measurements on an in vitro model system under similar conditions to what is expected in the nucleus. We conclude that the eukaryotic nucleus of living cells is a nonequilibrium soft material whose fluctuations are actively driven, and are far from thermal in their time dependence.

  12. Time-resolved PIV technique for high temporal resolution measurement of mechanical prosthetic aortic valve fluid dynamics.

    Science.gov (United States)

    Kaminsky, R; Morbiducci, U; Rossi, M; Scalise, L; Verdonck, P; Grigioni, M

    2007-02-01

    Prosthetic heart valves (PHVs) have been used to replace diseased native valves for more than five decades. Among these, mechanical PHVs are the most frequently implanted. Unfortunately, these devices still do not achieve ideal behavior and lead to many complications, many of which are related to fluid mechanics. The fluid dynamics of mechanical PHVs are particularly complex and the fine-scale characteristics of such flows call for very accurate experimental techniques. Adequate temporal resolution can be reached by applying time-resolved PIV, a high-resolution dynamic technique which is able to capture detailed chronological changes in the velocity field. The aim of this experimental study is to investigate the evolution of the flow field in a detailed time domain of a commercial bileaflet PHV in a mock-loop mimicking unsteady conditions, by means of time-resolved 2D Particle Image Velocimetry (PIV). The investigated flow field corresponded to the region immediately downstream of the valve plane. Spatial resolution as in "standard" PIV analysis of prosthetic valve fluid dynamics was used. The combination of a Nd:YLF high-repetition-rate double-cavity laser with a high frame rate CMOS camera allowed a detailed, highly temporally resolved acquisition (up to 10000 fps depending on the resolution) of the flow downstream of the PHV. Features that were observed include the non-homogeneity and unsteadiness of the phenomenon and the presence of large-scale vortices within the field, especially in the wake of the valve leaflets. Furthermore, we observed that highly temporally cycle-resolved analysis allowed the different behaviors exhibited by the bileaflet valve at closure to be captured in different acquired cardiac cycles. By accurately capturing hemodynamically relevant time scales of motion, time-resolved PIV characterization can realistically be expected to help designers in improving PHV performance and in furnishing comprehensive validation with experimental data

  13. Systematic study of the effects of mass and time scaling techniques applied in numerical rock mechanics simulations

    Science.gov (United States)

    Heinze, Thomas; Jansen, Gunnar; Galvan, Boris; Miller, Stephen A.

    2016-08-01

    Numerical modeling is a well established tool in rock mechanics studies investigating a wide range of problems. Implicit methods for solving linear equations have the advantage of being unconditionally stable, while explicit methods, although limited by the time step, are often used because of their limited memory demand, their scalability in parallel computing, and simple implementation of complex boundary conditions. In numerical modeling of explicit elastoplastic dynamics where the time step is limited by the material density, mass scaling techniques can be used to overcome this limit and significantly reduce computation time. While often used, the effect of mass and time scaling and how it may influence the numerical results is rarely-mentioned in publications, and choosing the right scaling technique is typically performed by trial and error. To our knowledge, no systematic studies have addressed how mass scaling might affect the numerical results. In this paper, we present results from an extensive and systematic study of the influence of mass and time scaling on the behavior of a variety of rock-mechanical models. We employ a finite difference scheme to model uniaxial and biaxial compression experiments using different mass and time scaling factors, and with physical models of increasing complexity up to a cohesion-weakening frictional-strengthening model (CWFS). We also introduce a normalized energy ratio to assist analyzing mass scaling effects. We find the tested models to be less sensitive to time scaling than to mass scaling, so mass scaling has higher potential for decreasing computational costs. However, we also demonstrate that mass scaling may lead to quantitatively wrong results, so care must be taken in interpreting stress values when mass scaling is used in complicated rock mechanics simulations. Mass scaling significantly influences the stress-strain response of numerical rocks because mass scaling acts as an artificial hardening agent on rock

  14. Enhancing Student Self-Study Attitude and Activity with Motivational Techniques

    Directory of Open Access Journals (Sweden)

    Kent Rhoads

    2013-09-01

    Full Text Available Research has shown that students will exhibit a positive attitude towards self-study, but that they will often fail to complete self-study activities. The purpose of this paper is to investigate positive instructor interactions and motivation of students to complete self- study activities and students’ attitudes towards self-study. Six English instructors at the University of Shizuoka created a one-semester self-access study log for use in the university self-access language laboratory in order to find out how many students would complete the log. One of the six instructors applied motivational techniques in the classroom in an effort to engender greater student self-study. Later a questionnaire was administered to 465 student participants to determine their self-study attitudes and activities. The data collected from the questionnaire and the high participation in the self- study activities suggest the positive impact the motivational actions employed by the instructor had on his students' attitudes towards self-study activities.

  15. Refolding Techniques for Recovering Biologically Active Recombinant Proteins from Inclusion Bodies

    Directory of Open Access Journals (Sweden)

    Hiroshi Yamaguchi

    2014-02-01

    Full Text Available Biologically active proteins are useful for studying the biological functions of genes and for the development of therapeutic drugs and biomaterials in a biotechnology industry. Overexpression of recombinant proteins in bacteria, such as Escherichia coli, often results in the formation of inclusion bodies, which are protein aggregates with non-native conformations. As inclusion bodies contain relatively pure and intact proteins, protein refolding is an important process to obtain active recombinant proteins from inclusion bodies. However, conventional refolding methods, such as dialysis and dilution, are time consuming and, often, recovered yields of active proteins are low, and a trial-and-error process is required to achieve success. Recently, several approaches have been reported to refold these aggregated proteins into an active form. The strategies largely aim at reducing protein aggregation during the refolding procedure. This review focuses on protein refolding techniques using chemical additives and laminar flow in microfluidic chips for the efficient recovery of active proteins from inclusion bodies.

  16. A novel integrated active capping technique for the remediation of nitrobenzene-contaminated sediment.

    Science.gov (United States)

    Sun, Hongwen; Xu, Xiaoyang; Gao, Guandao; Zhang, Zizhong; Yin, Peijie

    2010-10-15

    The objective of this study was to develop a novel integrated active capping system and to investigate its efficiency in the remediation of nitrobenzene-contaminated sediment. An integrated Fe(0)-sorbent-microorganism remediation system was proposed as an in situ active capping technique to remediate nitrobenzene-contaminated sediment. In this system, nitrobenzene was reduced to aniline by Fe(0), which has a much better biodegradability. The sorption capacity and structural properties of cinder was measured to examine its applicability as the sorbent and matrix for this integrated capping system. Indigenous microorganisms from Songhuajiang River sediment, which was contaminated by nitrobenzene and aniline in Chinese Petrochemical Explosion in Jilin, were acquired one month after the explosion and used in this active capping system to degrade nitrobenzene and its reduced product, aniline. A bench-scale remediation experiment was conducted on a mimicked nitrobenzene-contaminated sediment to investigate the efficiency of the integrated capping system and the synergistic effects of the combined components in the active capping system. The results show that this integrated active capping system can effectively block the release of target pollutants into the upper-layer water and remove the compounds from the environment.

  17. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Zhao Feng

    2015-01-01

    Full Text Available The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base post grouting pile, which has a certain reference value for theoretical research and technical application of the technique.

  18. Mechanisms of macrophage activation in obesity-induced insulin resistance

    OpenAIRE

    Odegaard, Justin I.; Chawla, Ajay

    2008-01-01

    Chronic inflammation is now recognized as a key step in the pathogenesis of obesity-induced insulin resistance and type 2 diabetes mellitus. This low-grade inflammation is mediated by the inflammatory (classical) activation of recruited and resident macrophages that populate metabolic tissues, including adipose tissue and liver. These findings have led to the concept that infiltration and activation of adipose tissue macrophages is causally linked to obesity-induced insulin resistance. Studie...

  19. In vitro and in vivo antitumor activity of Bulbus Fritillariae Cirrhosae and preliminary investigation of its mechanism.

    Science.gov (United States)

    Wang, Dong-Dong; Feng, Yong; Li, Zu; Zhang, Li; Wang, Shu; Zhang, Chao-Yang; Wang, Xiao-Xia; Liu, Zi-Yu

    2014-01-01

    Bulbus Fritillariae Cirrhosae (BFC) is widely used in China both for food and folk medicine because of its powerful biological activities. Firstly, this study was designed to examine the antiproliferative activities of the different fractions from BFC in vitro by MTT assay. The results showed that chloroform extracts (CE) and the purified total alkaloids of BFC (TAF) exhibited stronger antiproliferative activity than the other fractions. We further determined the total alkaloids and 3 main alkaloids monomers content of CE and TAF by UV and HPLC-ELSD methods, respectively. Moreover, we assessed the antitumor activity of TAF in vivo and made preliminary investigation of its antitumor mechanism by histological and immunohistochemical staining technique. These results demonstrate that TAF showed significant antitumor activity and low toxicity in vivo. Meanwhile, TAF significantly inhibited tumor angiogenesis and induced apoptosis by improvement of expression level of caspase-3. These results suggest that alkaloids of BFC could hold a good potential for use as an antitumor drug.

  20. The wiring of developing sensory circuits - from patterned spontaneous activity to mechanisms of synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Alexandra Helen Leighton

    2016-09-01

    Full Text Available In order to accurately process incoming sensory stimuli, neurons must be organized into functional networks, with both genetic and environmental factors influencing the precise arrangement of connections between cells. Teasing apart the relative contributions of molecular guidance cues, spontaneous activity and visual experience during this maturation is on-going. During development of the sensory system, the first, rough organization of connections is created by molecular factors. These connections are then modulated by the intrinsically generated activity of neurons, even before the senses have become operational. Spontaneous waves of depolarisations sweep across the nervous system, placing them in a prime position to strengthen correct connections and weaken others, shaping synapses into a useful network. A large body of work now supports the idea that, rather than being a mere side-effect of the system, spontaneous activity actually contains information which readies the nervous system so that, as soon as the senses become active, sensory information can be utilized by the animal. An example is the neonatal mouse. As soon as the eyelids first open, neurons in the cortex respond to visual information without the animal having previously encountered structured sensory input (Cang et al., 2005a; Ko et al., 2013; Rochefort et al., 2011; Zhang et al., 2012. In vivo imaging techniques have advanced considerably, allowing observation of the natural activity in the brain of living animals down to the level of the individual synapse. New (optogenetic methods make it possible to subtly modulate the spatio-temporal properties of activity, aiding our understanding of how these characteristics relate to the function of spontaneous activity. Such experiments have had a huge impact on our knowledge by permitting direct testing of ideas about the plasticity mechanisms at play in the intact system, opening up a provocative range of fresh questions. Here, we