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Sample records for optimization uptake mechanism

  1. Exosomes: Mechanisms of Uptake

    Directory of Open Access Journals (Sweden)

    Kelly J. McKelvey

    2015-07-01

    Full Text Available Exosomes are 30–100 nm microvesicles which contain complex cellular signals of RNA, protein and lipids. Because of this, exosomes are implicated as having limitless therapeutic potential for the treatment of cancer, pregnancy complications, infections, and autoimmune diseases. To date we know a considerable amount about exosome biogenesis and secretion, but there is a paucity of data regarding the uptake of exosomes by immune and non- immune cell types (e.g., cancer cells and the internal signalling pathways by which these exosomes elicit a cellular response. Answering these questions is of para‐ mount importance.

  2. Exosomes: Mechanisms of Uptake

    Directory of Open Access Journals (Sweden)

    Kelly J. McKelvey

    2015-07-01

    Full Text Available Exosomes are 30–100 nm microvesicles which contain complex cellular signals of RNA, protein and lipids. Because of this, exosomes are implicated as having limitless therapeutic potential for the treatment of cancer, pregnancy complications, infections, and autoimmune diseases. To date we know a considerable amount about exosome biogenesis and secretion, but there is a paucity of data regarding the uptake of exosomes by immune and non-immune cell types (e.g., cancer cells and the internal signalling pathways by which these exosomes elicit a cellular response. Answering these questions is of paramount importance.

  3. Mechanisms of Ocean Heat Uptake

    Science.gov (United States)

    Garuba, Oluwayemi

    An important parameter for the climate response to increased greenhouse gases or other radiative forcing is the speed at which heat anomalies propagate downward in the ocean. Ocean heat uptake occurs through passive advection/diffusion of surface heat anomalies and through the redistribution of existing temperature gradients due to circulation changes. Atlantic meridional overturning circulation (AMOC) weakens in a warming climate and this should slow the downward heat advection (compared to a case in which the circulation is unchanged). However, weakening AMOC also causes a deep warming through the redistributive effect, thus increasing the downward rate of heat propagation compared to unchanging circulation. Total heat uptake depends on the combined effect of these two mechanisms. Passive tracers in a perturbed CO2 quadrupling experiments are used to investigate the effect of passive advection and redistribution of temperature anomalies. A new passive tracer formulation is used to separate ocean heat uptake into contributions due to redistribution and passive advection-diffusion of surface heating during an ocean model experiment with abrupt increase in surface temperature. The spatial pattern and mechanisms of each component are examined. With further experiments, the effects of surface wind, salinity and temperature changes in changing circulation and the resulting effect on redistribution in the individual basins are isolated. Analysis of the passive advection and propagation path of the tracer show that the Southern ocean dominates heat uptake, largely through vertical and horizontal diffusion. Vertical diffusion transports the tracer across isopycnals down to about 1000m in 100 years in the Southern ocean. Advection is more important in the subtropical cells and in the Atlantic high latitudes, both with a short time scale of about 20 years. The shallow subtropical cells transport the tracer down to about 500m along isopycnal surfaces, below this vertical

  4. Routes and mechanisms of extracellular vesicle uptake

    Directory of Open Access Journals (Sweden)

    Laura Ann Mulcahy

    2014-08-01

    Full Text Available Extracellular vesicles (EVs are small vesicles released by donor cells that can be taken up by recipient cells. Despite their discovery decades ago, it has only recently become apparent that EVs play an important role in cell-to-cell communication. EVs can carry a range of nucleic acids and proteins which can have a significant impact on the phenotype of the recipient. For this phenotypic effect to occur, EVs need to fuse with target cell membranes, either directly with the plasma membrane or with the endosomal membrane after endocytic uptake. EVs are of therapeutic interest because they are deregulated in diseases such as cancer and they could be harnessed to deliver drugs to target cells. It is therefore important to understand the molecular mechanisms by which EVs are taken up into cells. This comprehensive review summarizes current knowledge of EV uptake mechanisms. Cells appear to take up EVs by a variety of endocytic pathways, including clathrin-dependent endocytosis, and clathrin-independent pathways such as caveolin-mediated uptake, macropinocytosis, phagocytosis, and lipid raft–mediated internalization. Indeed, it seems likely that a heterogeneous population of EVs may gain entry into a cell via more than one route. The uptake mechanism used by a given EV may depend on proteins and glycoproteins found on the surface of both the vesicle and the target cell. Further research is needed to understand the precise rules that underpin EV entry into cells.

  5. Feedforward non-Michaelis-Menten mechanism for CO(2) uptake by Rubisco: contribution of carbonic anhydrases and photorespiration to optimization of photosynthetic carbon assimilation.

    Science.gov (United States)

    Igamberdiev, Abir U; Roussel, Marc R

    2012-03-01

    Rubisco, the most abundant protein serving as the primary engine generating organic biomass on Earth, is characterized by a low catalytic constant (in higher plants approx. 3s(-1)) and low specificity for CO(2) leading to photorespiration. We analyze here why this enzyme evolved as the main carbon fixation engine. The high concentration of Rubisco exceeding the concentration of its substrate CO(2) by 2-3 orders of magnitude makes application of Michaelis-Menten kinetics invalid and requires alternative kinetic approaches to describe photosynthetic CO(2) assimilation. Efficient operation of Rubisco is supported by a strong flux of CO(2) to the chloroplast stroma provided by fast equilibration of bicarbonate and CO(2) and forwarding the latter to Rubisco reaction centers. The main part of this feedforward mechanism is a thylakoidal carbonic anhydrase associated with photosystem II and pumping CO(2) from the thylakoid lumen in coordination with the rate of electron transport, water splitting and proton gradient across the thylakoid membrane. This steady flux of CO(2) limits photosynthesis at saturating CO(2) concentrations. At low ambient CO(2) and correspondingly limited capacity of the bicarbonate pool in the stroma, its depletion at the sites of Rubisco is relieved by utilizing O(2) instead of CO(2), i.e. by photorespiration, a process which supplies CO(2) back to Rubisco and buffers the redox state and energy level in the chloroplast. Thus, the regulation of Rubisco function aims to keep steady non-equilibrium levels of CO(2), NADPH/NADP and ATP/ADP in the chloroplast stroma and to optimize the condition of homeostatic photosynthetic flux of matter and energy. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  6. Classification and uptake of reservoir operation optimization methods

    Science.gov (United States)

    Dobson, Barnaby; Pianosi, Francesca; Wagener, Thorsten

    2016-04-01

    Reservoir operation optimization algorithms aim to improve the quality of reservoir release and transfer decisions. They achieve this by creating and optimizing the reservoir operating policy; a function that returns decisions based on the current system state. A range of mathematical optimization algorithms and techniques has been applied to the reservoir operation problem of policy optimization. In this work, we propose a classification of reservoir optimization approaches by focusing on the formulation of the water management problem rather than the optimization algorithm type. We believe that decision makers and operators will find it easier to navigate a classification system based on the problem characteristics, something they can clearly define, rather than the optimization algorithm. Part of this study includes an investigation regarding the extent of algorithm uptake and the possible reasons that limit real world application.

  7. Mechanisms and regulation of Na(+) uptake by freshwater fish.

    Science.gov (United States)

    Kumai, Yusuke; Perry, Steve F

    2012-12-01

    Mechanisms of ion uptake by freshwater (FW) fish have received considerable attention over the past 80 years. Through an assortment of techniques incorporating whole animal physiology, electrophysiology and molecular biological approaches, three models have been proposed to account for Na(+) uptake. (1) Direct exchange of Na(+) and H(+) via one or more types of Na(+)/H(+) exchanger (slc9), (2) uptake of Na(+) through epithelial Na(+) channels energized by an electrical gradient created by H(+)-ATPase and (3) Na(+)/Cl(-) co-transport (slc12). While each mechanism is supported at least in part by theoretical or experimental data, there are several outstanding questions that have not yet been fully resolved. Furthermore, there are few details concerning how these Na(+) uptake mechanisms are fine tuned in response to the fluctuating FW environments. In this review, we summarize the current understanding of these three Na(+) uptake mechanisms and discuss their regulation by endocrine (cortisol and prolactin) and neurohumoral (catecholamines) factors.

  8. 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 ...

  9. Water Uptake Mechanism in Crispy Bread Crust

    NARCIS (Netherlands)

    Nieuwenhuijzen, van N.H.; Meinders, M.B.J.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.

    2008-01-01

    Crispness is an important quality characteristic of dry solid food products such as crispy rolls. Its retention is directly related to the kinetics of water uptake by the crust. In this study, a method for the evaluation of the water sorption kinetics in bread crust is proposed. Two different sorpti

  10. Different endocytotic uptake mechanisms for nanoparticles in epithelial cells and macrophages

    Directory of Open Access Journals (Sweden)

    Dagmar A. Kuhn

    2014-09-01

    Full Text Available Precise knowledge regarding cellular uptake of nanoparticles is of great importance for future biomedical applications. Four different endocytotic uptake mechanisms, that is, phagocytosis, macropinocytosis, clathrin- and caveolin-mediated endocytosis, were investigated using a mouse macrophage (J774A.1 and a human alveolar epithelial type II cell line (A549. In order to deduce the involved pathway in nanoparticle uptake, selected inhibitors specific for one of the endocytotic pathways were optimized regarding concentration and incubation time in combination with fluorescently tagged marker proteins. Qualitative immunolocalization showed that J774A.1 cells highly expressed the lipid raft-related protein flotillin-1 and clathrin heavy chain, however, no caveolin-1. A549 cells expressed clathrin heavy chain and caveolin-1, but no flotillin-1 uptake-related proteins. Our data revealed an impeded uptake of 40 nm polystyrene nanoparticles by J774A.1 macrophages when actin polymerization and clathrin-coated pit formation was blocked. From this result, it is suggested that macropinocytosis and phagocytosis, as well as clathrin-mediated endocytosis, play a crucial role. The uptake of 40 nm nanoparticles in alveolar epithelial A549 cells was inhibited after depletion of cholesterol in the plasma membrane (preventing caveolin-mediated endocytosis and inhibition of clathrin-coated vesicles (preventing clathrin-mediated endocytosis. Our data showed that a combination of several distinguishable endocytotic uptake mechanisms are involved in the uptake of 40 nm polystyrene nanoparticles in both the macrophage and epithelial cell line.

  11. Optimal Control of Mechanical Systems

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    Vadim Azhmyakov

    2007-01-01

    Full Text Available In the present work, we consider a class of nonlinear optimal control problems, which can be called “optimal control problems in mechanics.” We deal with control systems whose dynamics can be described by a system of Euler-Lagrange or Hamilton equations. Using the variational structure of the solution of the corresponding boundary-value problems, we reduce the initial optimal control problem to an auxiliary problem of multiobjective programming. This technique makes it possible to apply some consistent numerical approximations of a multiobjective optimization problem to the initial optimal control problem. For solving the auxiliary problem, we propose an implementable numerical algorithm.

  12. Optimal Control of Mechanical Systems

    OpenAIRE

    Vadim Azhmyakov

    2007-01-01

    In the present work, we consider a class of nonlinear optimal control problems, which can be called “optimal control problems in mechanics.” We deal with control systems whose dynamics can be described by a system of Euler-Lagrange or Hamilton equations. Using the variational structure of the solution of the corresponding boundary-value problems, we reduce the initial optimal control problem to an auxiliary problem of multiobjective programming. This technique makes it possible to apply some ...

  13. Nanodiamond internalization in cells and the cell uptake mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Perevedentseva, E. [National Dong Hwa University, Department of Physics (China); Hong, S.-F.; Huang, K.-J. [National Dong Hwa University, Department of Life Sciences (China); Chiang, I.-T.; Lee, C.-Y. [National Dong Hwa University, Department of Physics (China); Tseng, Y.-T. [National Dong Hwa University, Department of Life Sciences (China); Cheng, C.-L., E-mail: clcheng@mail.ndhu.edu.tw [National Dong Hwa University, Department of Physics (China)

    2013-08-15

    Cell type-dependent penetration of nanodiamond in living cells is one of the important factors for using nanodiamond as cellular markers/labels, for drug delivery as well as for other biomedical applications. In this work, internalization of 100 nm nanodiamonds by A549 lung human adenocarcinoma cell, Beas-2b non-tumorigenic human bronchial epithelial cell, and HFL-1 fibroblast-like human fetal lung cell is studied and compared. The penetration of nanodiamond into the cells was observed using confocal fluorescence imaging and Raman imaging methods. Visualization of the nanodiamond in cells allows comparison of the internalization for diamond nanoparticles in cancer A549 cell, non-cancer HFL-1, and Beas-2b cells. The dose-dependent and time-dependent behavior of nanodiamond uptake is observed in both cancer as well as non-cancer cells. The mechanism of nanodiamond uptake by cancer and non-cancer cells is analyzed by blocking different pathways. The uptake of nanodiamond in both cancer and non-cancer cells was found predominantly via clathrin-dependent endocytosis. In spite of observed similarity in the uptake mechanism for cancer and non-cancer cells, the nanodiamond uptake for cancer cell quantitatively exceeds the uptake for non-cancer cells, for the studied cell lines. The observed difference in internalization of nanodiamond by cancer and non-cancer cells is discussed.

  14. Nanodiamond internalization in cells and the cell uptake mechanism

    Science.gov (United States)

    Perevedentseva, E.; Hong, S.-F.; Huang, K.-J.; Chiang, I.-T.; Lee, C.-Y.; Tseng, Y.-T.; Cheng, C.-L.

    2013-08-01

    Cell type-dependent penetration of nanodiamond in living cells is one of the important factors for using nanodiamond as cellular markers/labels, for drug delivery as well as for other biomedical applications. In this work, internalization of 100 nm nanodiamonds by A549 lung human adenocarcinoma cell, Beas-2b non-tumorigenic human bronchial epithelial cell, and HFL-1 fibroblast-like human fetal lung cell is studied and compared. The penetration of nanodiamond into the cells was observed using confocal fluorescence imaging and Raman imaging methods. Visualization of the nanodiamond in cells allows comparison of the internalization for diamond nanoparticles in cancer A549 cell, non-cancer HFL-1, and Beas-2b cells. The dose-dependent and time-dependent behavior of nanodiamond uptake is observed in both cancer as well as non-cancer cells. The mechanism of nanodiamond uptake by cancer and non-cancer cells is analyzed by blocking different pathways. The uptake of nanodiamond in both cancer and non-cancer cells was found predominantly via clathrin-dependent endocytosis. In spite of observed similarity in the uptake mechanism for cancer and non-cancer cells, the nanodiamond uptake for cancer cell quantitatively exceeds the uptake for non-cancer cells, for the studied cell lines. The observed difference in internalization of nanodiamond by cancer and non-cancer cells is discussed.

  15. Regulatory mechanisms for glycogenolysis and K+ uptake in brain astrocytes.

    Science.gov (United States)

    DiNuzzo, Mauro; Mangia, Silvia; Maraviglia, Bruno; Giove, Federico

    2013-11-01

    Recent advances in brain energy metabolism support the notion that glycogen in astrocytes is necessary for the clearance of neuronally-released K(+) from the extracellular space. However, how the multiple metabolic pathways involved in K(+)-induced increase in glycogen turnover are regulated is only partly understood. Here we summarize the current knowledge about the mechanisms that control glycogen metabolism during enhanced K(+) uptake. We also describe the action of the ubiquitous Na(+)/K(+) ATPase for both ion transport and intracellular signaling cascades, and emphasize its importance in understanding the complex relation between glycogenolysis and K(+) uptake.

  16. Distinct Therapeutic Mechanisms of Tau Antibodies: Promoting Microglial Clearance Versus Blocking Neuronal Uptake.

    Science.gov (United States)

    Funk, Kristen E; Mirbaha, Hilda; Jiang, Hong; Holtzman, David M; Diamond, Marc I

    2015-08-28

    Tauopathies are neurodegenerative diseases characterized by accumulation of Tau amyloids, and include Alzheimer disease and certain frontotemporal dementias. Trans-neuronal propagation of amyloid mediated by extracellular Tau may underlie disease progression. Consistent with this, active and passive vaccination studies in mouse models reduce pathology, although by unknown mechanisms. We previously reported that intracerebroventricular administration of three anti-Tau monoclonal antibodies (HJ8.5, HJ9.3, and HJ9.4) reduces pathology in a model overexpressing full-length mutant (P301S) human Tau. We now study effects of these three antibodies and a negative control antibody (HJ3.4) on Tau aggregate uptake into BV2 microglial-like cells and primary neurons. Antibody-independent Tau uptake into BV2 cells was blocked by heparin, consistent with a previously described role for heparan sulfate proteoglycans. Two therapeutic antibodies (HJ8.5 and HJ9.4) promoted uptake of full-length Tau fibrils into microglia via Fc receptors. Surprisingly, HJ9.3 promoted uptake of fibrils composed of the Tau repeat domain or Alzheimer disease-derived Tau aggregates, but failed to influence full-length recombinant Tau fibrils. Size fractionation of aggregates showed that antibodies preferentially promote uptake of larger oligomers (n ≥ ∼ 20-mer) versus smaller oligomers (n ∼ 10-mer) or monomer. No antibody inhibited uptake of full-length recombinant fibrils into primary neurons, but HJ9.3 blocked neuronal uptake of Tau repeat domain fibrils and Alzheimer disease-derived Tau. Antibodies thus have multiple potential mechanisms, including clearance via microglia and blockade of neuronal uptake. However these effects are epitope- and aggregate size-dependent. Establishing specific mechanisms of antibody activity in vitro may help in design and optimization of agents that are more effective in vivo. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Dynamics and mechanisms of quantum dot nanoparticle cellular uptake

    Directory of Open Access Journals (Sweden)

    Telford William G

    2010-06-01

    Full Text Available Abstract Background The rapid growth of the nanotechnology industry and the wide application of various nanomaterials have raised concerns over their impact on the environment and human health. Yet little is known about the mechanism of cellular uptake and cytotoxicity of nanoparticles. An array of nanomaterials has recently been introduced into cancer research promising for remarkable improvements in diagnosis and treatment of the disease. Among them, quantum dots (QDs distinguish themselves in offering many intrinsic photophysical properties that are desirable for targeted imaging and drug delivery. Results We explored the kinetics and mechanism of cellular uptake of QDs with different surface coatings in two human mammary cells. Using fluorescence microscopy and laser scanning cytometry (LSC, we found that both MCF-7 and MCF-10A cells internalized large amount of QD655-COOH, but the percentage of endocytosing cells is slightly higher in MCF-7 cell line than in MCF-10A cell line. Live cell fluorescent imaging showed that QD cellular uptake increases with time over 40 h of incubation. Staining cells with dyes specific to various intracellular organelles indicated that QDs were localized in lysosomes. Transmission electron microscopy (TEM images suggested a potential pathway for QD cellular uptake mechanism involving three major stages: endocytosis, sequestration in early endosomes, and translocation to later endosomes or lysosomes. No cytotoxicity was observed in cells incubated with 0.8 nM of QDs for a period of 72 h. Conclusions The findings presented here provide information on the mechanism of QD endocytosis that could be exploited to reduce non-specific targeting, thereby improving specific targeting of QDs in cancer diagnosis and treatment applications. These findings are also important in understanding the cytotoxicity of nanomaterials and in emphasizing the importance of strict environmental control of nanoparticles.

  18. Theoretical considerations underlying Na(+) uptake mechanisms in freshwater fishes.

    Science.gov (United States)

    Parks, Scott K; Tresguerres, Martin; Goss, Greg G

    2008-11-01

    Ion and acid-base regulating mechanisms have been studied at the fish gill for almost a century. Original models proposed for Na(+) and Cl(-) uptake, and their linkage with H(+) and HCO(3)(-) secretion have changed substantially with the development of more sophisticated physiological techniques. At the freshwater fish gill, two dominant mechanisms for Na(+) uptake from dilute environments have persisted in the literature. The use of an apical Na(+)/H(+) exchanger driven by a basolateral Na(+)/K(+)-ATPase versus an apical Na(+) channel electrogenically coupled to an apical H(+)-ATPase have been the source of debate for a number of years. Advances in molecular biology have greatly enhanced our understanding of the basic ion transport mechanisms at the fish gill. However, it is imperative to ensure that thermodynamic principles are followed in the development of new models for gill ion transport. This review will focus on the recent molecular advances for Na(+) uptake in freshwater fish. Emphasis will be placed on thermodynamic constraints that prevent electroneutral apical NHE function in most freshwater environments. By combining recent advances in molecular and functional physiology of fish gills with thermodynamic considerations of ion transport, our knowledge in the field should continue to grow in a logical manner.

  19. Mechanisms of Enhanced Rice Growth and Nitrogen Uptake by Nitrate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Rice is being increasingly cultivated in intermittently irrigated regions and also in aerobic soil in which Nitrate (NO3-)plays important role in nutrition of plant. However, there is no information regarding the influence of nitrate on the overall growth and uptake of nitrogen (N) in rice plant. Solution culture experiments were carried out to study the effects of NO3-on the plant growth, uptake of N, and uptake kinetics of NH4+ in four typical rice (Oryza sativa L.) cultivars (conventional indica, conventional japonica, hybrid indica, and hybrid japonica), and on plasma membrane potential in roots of two conventional rice cultivars (indica and japonica) at the seedling stage. The results obtained indicated that a ratio of 50/50 NH4+-N/NO3--N increased the average biomass of rice shoots and roots by 20% when compared with that of 100/0NH4+-N/NO3--N. In case of the 50/50 ratio, as compared with the 100/0 ratio, total N accumulated in shoots and roots of rice increased on an average by 42% and 57%, respectively. Conventional indica responds to NO3- more than any other cultivars that were tested. The NO3- supply increased the maximum uptake rate (Vmax) of NH4+ by rice but did not show any effect on the apparent Michaelis-Menten constant (Km) value, with the average value of Vmax for NH4+ among the four cultivars being increased by 31.5% in comparison with those in the absence of NO3-. This suggested that NO3-significantly increased the numbers of the ammonium transporters. However, the lack of effect on the Km value also suggested that the presence of NO3- had no effect on the affinity of the transporters for NH4+. The plasma membrane potential in the roots of conventional indica and japonica were greatly increased by the addition of NO3-, suggesting that NO3- could improve the uptake of N by roots of the rice plant. In conclusion, the mechanisms by which NO3- enhances the growth and N uptake of rice plant was found by the increased value of Vmax of NH4+ and

  20. Trans-membrane transport of fluoranthene by Rhodococcus sp. BAP-1 and optimization of uptake process.

    Science.gov (United States)

    Li, Yi; Wang, Hongqi; Hua, Fei; Su, Mengyuan; Zhao, Yicun

    2014-03-01

    The mechanism of transport of (14)C-fluoranthene by Rhodococcus sp. BAP-1, a Gram-positive bacterium isolated from crude oil-polluted soil, was examined. Our finding demonstrated that the mechanism for fluoranthene travel across the cell membrane in Rhodococcus sp. BAP-1 requires energy. Meanwhile, the transport of fluoranthene involves concurrent catabolism of (14)C, that leading to the generation of significant amount of (14)CO2. Combined with trans-membrane transport dynamic and response surface methodology, a significant influence of temperature, pH and salinity on cellular uptake rate was screened by Plackett-Burman design. Then, Box-Behnken design was employed to optimize and enhanced the trans-membrane transport process. The results predicted by Box-Behnken design indicated that the maximum cellular uptake rate of fluoranthene could be achieve to 0.308μmolmin(-1)mg(-1)·protein (observed) and 0.304μmolmin(-1)mg(-1)·protein (predicted) when the initial temperature, pH and salinity were set at 20°C, 9% and 1%, respectively.

  1. Basolateral Cl- uptake mechanisms in Xenopus laevis lung epithelium.

    Science.gov (United States)

    Berger, Jens; Hardt, Martin; Clauss, Wolfgang G; Fronius, Martin

    2010-07-01

    A thin liquid layer covers the lungs of air-breathing vertebrates. Active ion transport processes via the pulmonary epithelial cells regulate the maintenance of this layer. This study focuses on basolateral Cl(-) uptake mechanisms in native lungs of Xenopus laevis and the involvement of the Na(+)/K(+)/2 Cl(-) cotransporter (NKCC) and HCO(3)(-)/Cl(-) anion exchanger (AE), in particular. Western blot analysis and immunofluorescence staining revealed the expression of the NKCC protein in the Xenopus lung. Ussing chamber experiments demonstrated that the NKCC inhibitors (bumetanide and furosemide) were ineffective at blocking the cotransporter under basal conditions, as well as under pharmacologically stimulated Cl(-)-secreting conditions (forskolin and chlorzoxazone application). However, functional evidence for the NKCC was detected by generating a transepithelial Cl(-) gradient. Further, we were interested in the involvement of the HCO(3)(-)/Cl(-) anion exchanger to transepithelial ion transport processes. Basolateral application of DIDS, an inhibitor of the AE, resulted in a significantly decreased the short-circuit current (I(SC)). The effect of DIDS was diminished by acetazolamide and reduced by increased external HCO(3)(-) concentrations. Cl(-) secretion induced by forskolin was decreased by DIDS, but this effect was abolished in the presence of HCO(3)(-). These experiments indicate that the AE at least partially contributes to Cl(-) secretion. Taken together, our data show that in Xenopus lung epithelia, the AE, rather than the NKCC, is involved in basolateral Cl(-) uptake, which contrasts with the common model for Cl(-) secretion in pulmonary epithelia.

  2. QUADRATIC OPTIMIZATION METHOD AND ITS APPLICATION ON OPTIMIZING MECHANISM PARAMETER

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yun; CHEN Jianneng; YU Yaxin; YU Gaohong; ZHU Jianping

    2006-01-01

    In order that the mechanism designed meets the requirements of kinematics with optimal dynamics behaviors, a quadratic optimization method is proposed based on the different characteristics of kinematic and dynamic optimization. This method includes two steps of optimization, that is, kinematic and dynamic optimization. Meanwhile, it uses the results of the kinematic optimization as the constraint equations of dynamic optimization. This method is used in the parameters optimization of transplanting mechanism with elliptic planetary gears of high-speed rice seedling transplanter with remarkable significance. The parameters spectrum, which meets to the kinematic requirements, is obtained through visualized human-computer interactions in the kinematics optimization, and the optimal parameters are obtained based on improved genetic algorithm in dynamic optimization. In the dynamic optimization, the objective function is chosen as the optimal dynamic behavior and the constraint equations are from the results of the kinematic optimization. This method is suitable for multi-objective optimization when both the kinematic and dynamic performances act as objective functions.

  3. Characterization of a possible uptake mechanism of selective antibacterial peptides.

    Science.gov (United States)

    Polanco, Carlos; Samaniego, José Lino; Castañón-González, Jorge Alberto; Buhse, Thomas; Sordo, Marili Leopold

    2013-01-01

    Selective antibacterial peptides containing less than 30 amino acid residues, cationic, with amphipathic properties, have been the subject of several studies due to their active participation and beneficial effects in strengthening the immune system of all living organisms. This manuscript reports the results of a comparison between the group of selective antibacterial peptides and another group called "cell penetrating peptides". An important number of the selective antibacterial peptides are cell penetrating peptides, suggesting that their toxicity is related to their uptake mechanism. The verification of this observation also includes the adaptation of a method previously published, called Polarity index, which reproduces and confirms the action of this new set of peptides. The efficiency of this method was verified based on four different databases, yielding a high score. The verification was based exclusively on the peptides already reported in the databases which have been experimentally verified.

  4. Optimization of mechanical structures using particle swarm optimization

    Energy Technology Data Exchange (ETDEWEB)

    Leite, Victor C.; Schirru, Roberto, E-mail: victor.coppo.leite@lmp.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (LMP/PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Monitoracao de Processos

    2015-07-01

    Several optimization problems are dealed with the particle swarm optimization (PSO) algorithm, there is a wide kind of optimization problems, it may be applications related to logistics or the reload of nuclear reactors. This paper discusses the use of the PSO in the treatment of problems related to mechanical structure optimization. The geometry and material characteristics of mechanical components are important for the proper functioning and performance of the systems were they are applied, particularly to the nuclear field. Calculations related to mechanical aspects are all made using ANSYS, while the PSO is programed in MATLAB. (author)

  5. Feedback inhibition of ammonium uptake by a phospho-dependent allosteric mechanism in Arabidopsis.

    Science.gov (United States)

    Lanquar, Viviane; Loqué, Dominique; Hörmann, Friederike; Yuan, Lixing; Bohner, Anne; Engelsberger, Wolfgang R; Lalonde, Sylvie; Schulze, Waltraud X; von Wirén, Nicolaus; Frommer, Wolf B

    2009-11-01

    The acquisition of nutrients requires tight regulation to ensure optimal supply while preventing accumulation to toxic levels. Ammonium transporter/methylamine permease/rhesus (AMT/Mep/Rh) transporters are responsible for ammonium acquisition in bacteria, fungi, and plants. The ammonium transporter AMT1;1 from Arabidopsis thaliana uses a novel regulatory mechanism requiring the productive interaction between a trimer of subunits for function. Allosteric regulation is mediated by a cytosolic C-terminal trans-activation domain, which carries a conserved Thr (T460) in a critical position in the hinge region of the C terminus. When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex. This study shows that phosphorylation of T460 is triggered by ammonium in a time- and concentration-dependent manner. Neither Gln nor l-methionine sulfoximine-induced ammonium accumulation were effective in inducing phosphorylation, suggesting that roots use either the ammonium transporter itself or another extracellular sensor to measure ammonium concentrations in the rhizosphere. Phosphorylation of T460 in response to an increase in external ammonium correlates with inhibition of ammonium uptake into Arabidopsis roots. Thus, phosphorylation appears to function in a feedback loop restricting ammonium uptake. This novel autoregulatory mechanism is capable of tuning uptake capacity over a wide range of supply levels using an extracellular sensory system, potentially mediated by a transceptor (i.e., transporter and receptor).

  6. Optimization of hepatocarcinoma uptake with radiolabeled lipiodol: development of new lipiodol formulations with increased viscosity.

    Science.gov (United States)

    Becker, Stéphanie; Lepareur, Nicolas; Cadeillan, Virginie; Ardisson, Valérie; Bayat, Sahar; Noiret, Nicolas; Garin, Etienne

    2012-03-01

    The aim of this study was to develop new Lipiodol formulations with increased viscosities to augment Lipiodol embolic effect and optimize efficiency of radiolabeled Lipiodol in hepatocarcinoma treatments. New Lipiodol formulations consist of Lipiodol mixtures with different stearic acid concentrations (0.8%, 1.3%, and 1.8%). These formulations were fully characterized in vitro (viscosity, rheologic profiles) and labeled with 99mTc. Their viscosities at 20°C are 54, 60, and 67cP respectively, versus 45cP for Lipiodol ultra-fluide. Second, their biodistribution profiles were studied in vivo, at 24 and 72 hours, in hepatoma-bearing rats, and compared to control group (99mTc-Lipiodol). Biodistribution at 24 hours show a Gaussian tumor uptake profile with a maximum obtained with 1.3% stearic acid, and a tumor uptake superior to control group (+67%) (p<0.05). At 72 hours, optimal tumor uptake is reached with the 0.8% formulation, with 89% increase compared with control group (p<0.05). Moreover, we show a tendency to the decrease of pulmonary uptake for the new formulations at 24 hours and 72 hours. These results suggest a correlation between viscosity and Lipiodol tumor uptake. The new 0.8% stearic acid/Lipiodol formulation appears to be the optimized formulation for Lipiodol treatments of hepatocarcinoma, since it leads to a significant increase of tumor uptake at 72 hours and possibly to a decrease of undesirable pulmonary effects.

  7. Cr(VI) uptake mechanism of Bacillus cereus.

    Science.gov (United States)

    Chen, Zhi; Huang, Zhipeng; Cheng, Yangjian; Pan, Danmei; Pan, Xiaohong; Yu, Meijuan; Pan, Zhiyun; Lin, Zhang; Guan, Xiong; Wu, Ziyu

    2012-04-01

    In this study, we investigated the Cr(VI) uptake mechanism in an indigenous Cr(VI)-tolerant bacterial strain -Bacillus cereus through batch and microscopic experiments. We found that both the cells and the supernatant collected from B. cereus cultivation could reduce Cr(VI). The valence state analysis revealed the complete transformation from Cr(VI) into Cr(III) by living B. cereus. Further X-ray absorption fine structure and Fourier transform infrared analyses showed that the reduced Cr(III) was coordinated with carboxyl and amido functional groups from either the cells or supernatant. Scanning electron microscopy and atomic force microscopy observation showed that noticeable Cr(III) precipitates were accumulated on bacterial surfaces. However, Cr(III) could also be detected in bacterial inner portions by using transmission electron microscopy thin section analysis coupled with energy dispersive X-ray spectroscopy. Through quantitative analysis of chromium distribution, we determined the binding ratio of Cr(III) in supernatant, cell debris and cytoplasm as 22%, 54% and 24%, respectively. Finally, we further discussed the role of bacterium-origin soluble organic molecules to the remediation of Cr(VI) pollutants.

  8. Mechanical and geometric advantages in compliant mechanism optimization

    Institute of Scientific and Technical Information of China (English)

    Michael Yu WANG

    2009-01-01

    This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formula-tions of compliant mechanisms posed as a topology optimization problem. With a linear elastic structuralanalysis, we quantify mechanical (and geometric) advan-tage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formula-tions.

  9. An improved group search optimizer for mechanical design optimization problems

    Institute of Scientific and Technical Information of China (English)

    Hai Shen; Yunlong Zhu; Ben Niu; Q.H. Wu

    2009-01-01

    This paper presents an improved group search optimizer (iGSO) for solving mechanical design optimization problems.In the pro-posed algorithm,subpopulations and a co-operation evolutionary strategy were adopted to improve the global search capability and convergence performance.The iGSO is evaluated on two optimization problems of classical mechanical design:spring and pressure vessel.The experimental results are analyzed in comparison with those reported in the literatures.The results show that iGSO has much better convergence performance and is easier to implement in comparison with other existing evolutionary algorithms.

  10. Intestinal uptake of bone seeking radiotracer: possible mechanisms and review of the literature

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. W.; Kim, C. G.; Park, S. A.; Chang, J. A. [WonKwang University Hospital, Iksan (Korea, Republic of)

    2007-07-01

    This study was undertaken to investigate the frequency of intestinal accumulation of Tc-99m 3, 3-diphosphono-1, 2-propanedicarboxylic acid (DPD) on bone scans, describe the patterns of intestinal Tc-99m DPD uptake and discuss the possible mechanisms of this unusual finding. Three thousand, one hundred and ninety-four consecutive patients have been evaluated for intestinal Tc-99m DPD uptake on bone scans. A whole-body bone scan and various spot views were obtained to evaluate the location and intensity of intestinal uptake. Delayed scan and SPECT study were performed to define characteristics of intestinal uptake in some of patients. Available reports of co-relative radiologic imaging, endoscopic studies and laboratory tests were also reviewed to explain the intestinal uptake. Eighteen (9 female, 9 male) patients out of 3194 with a mean age of 57 years showed intestinal Tc-99m DPD uptake. The locations of intestinal uptake were well dispersed throughout the abdomen. The majority of the cases showed lower intensity than iliac spine (12/18, 67%). Eight patients didn't show significant change of uptake characteristics on the delayed images, while intestinal uptake traveled distally in nine patients. Two cases were revealed uptake of peritoneal carcinomatosis with small amount ascites and three cases were revealed tumoral uptake of intestine. Four patients with gastritis showed similar characteristic of intestinal uptake. Six cases of distally traveled intestinal uptake suggested intraluminal Tc-99m DPD activity such as gastrointestinal bleeding. However, stool occult blood tests were negative in three patients, and there is no clinical evidence of gastrointestinal bleeding in other three patients. Intestinal Tc-99m DPD uptake can be observed in 0.5% of bone scans. The mechanism of intestinal uptake is still unclear in some of the patients. Delayed imaging additional spot views and SPECT studies help in the differentiation of this finding from possible

  11. The Stirling engine mechanism optimization

    Directory of Open Access Journals (Sweden)

    Jiří Podešva

    2016-03-01

    Full Text Available A special type of the gas engine with external combustion is called Stirling engine. The mechanism has two pistons with two volumes inside. The pistons are connected together through cooler, regenerator and warmer. The engine effectivity depends on the piston movement behaviour. The usual sinusoidal time curve leads to low effectiveness. The quick movement from lower to upper position with a certain delay in both top and bottom dead centres is more effective. The paper deals with three types of mechanisms, analyzing the piston movement, and their behavior. Special emphasize is taken to the piston movement regime.

  12. Exact and Optimal Quantum Mechanics/Molecular Mechanics Boundaries.

    Science.gov (United States)

    Sun, Qiming; Chan, Garnet Kin-Lic

    2014-09-09

    Motivated by recent work in density matrix embedding theory, we define exact link orbitals that capture all quantum mechanical (QM) effects across arbitrary quantum mechanics/molecular mechanics (QM/MM) boundaries. Exact link orbitals are rigorously defined from the full QM solution, and their number is equal to the number of orbitals in the primary QM region. Truncating the exact set yields a smaller set of link orbitals optimal with respect to reproducing the primary region density matrix. We use the optimal link orbitals to obtain insight into the limits of QM/MM boundary treatments. We further analyze the popular general hybrid orbital (GHO) QM/MM boundary across a test suite of molecules. We find that GHOs are often good proxies for the most important optimal link orbital, although there is little detailed correlation between the detailed GHO composition and optimal link orbital valence weights. The optimal theory shows that anions and cations cannot be described by a single link orbital. However, expanding to include the second most important optimal link orbital in the boundary recovers an accurate description. The second optimal link orbital takes the chemically intuitive form of a donor or acceptor orbital for charge redistribution, suggesting that optimal link orbitals can be used as interpretative tools for electron transfer. We further find that two optimal link orbitals are also sufficient for boundaries that cut across double bonds. Finally, we suggest how to construct "approximately" optimal link orbitals for practical QM/MM calculations.

  13. DESIGN OPTIMIZATION METHOD USED IN MECHANICAL ENGINEERING

    Directory of Open Access Journals (Sweden)

    SCURTU Iacob Liviu

    2016-11-01

    Full Text Available This paper presents an optimization study in mechanical engineering. First part of the research describe the structural optimization method used, followed by the presentation of several optimization studies conducted in recent years. The second part of the paper presents the CAD modelling of an agricultural plough component. The beam of the plough is analysed using finite element method. The plough component is meshed in solid elements, and the load case which mimics the working conditions of agricultural equipment of this are created. The model is prepared to find the optimal structural design, after the FEA study of the model is done. The mass reduction of part is the criterion applied for this optimization study. The end of this research presents the final results and the model optimized shape.

  14. Topology optimization of fluid mechanics problems

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Allan

    While topology optimization for solid continuum structures have been studied for about 20 years and for the special case of trusses for many more years, topology optimization of fluid mechanics problems is more recent. Borrvall and Petersson [1] is the seminal reference for topology optimization...... with respect to minimizing the energy loss, characteristic properties of the velocity field or mixing properties. To reduce the computational complexity of the topology optimization problems the primary focus is put on the Stokes equation in 2D and in 3D. However, the the talk also contains examples with the 2......D Navier-Stokes equation as well as an example with convection dominated transport in 2D Stokes flow. Using Stokes flow limits the range of applications; nonetheless, the present work gives a proof-of-concept for the application of the method within fluid mechanics problems and it remains...

  15. 'Optimal' vortex rings and aquatic propulsion mechanisms

    Science.gov (United States)

    Linden, Paul; Turner, Stewart

    2004-11-01

    Fish swim by flapping their tail and other fins. Other sea creatures, such as squid and salps, eject fluid intermittently as a jet. We discuss the fluid mechanics behind these propulsion mechanisms, and show that these animals produce optimal vortex rings, which give the maximum thrust for a given energy input. We show fish optimise both their steady swimming and their ability to accelerate and turn by producing an individual optimal ring with each flap of the tail or fin. Salps produce vortex rings directly by ejecting a volume of fluid through a rear orifice, and these are also optimal. An important implication of this paper is that the repetition of vortex production is not necessary for an individual vortex to have the `optimal' characteristics.

  16. Comparative analysis of nitrite uptake and hemoglobin-nitrite reactions in erythrocytes: sorting out uptake mechanisms and oxygenation dependencies

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Rohde, Sabina

    2010-01-01

    Nitrite uptake into red blood cells (RBCs) precedes its intracellular reactions with hemoglobin (Hb) that forms nitric oxide (NO) during hypoxia. We investigated the uptake of nitrite and its reactions with Hb at different oxygen saturations (So2), using RBCs with (carp and rabbit) and without...... (hagfish and lamprey) anion exchanger-1 (AE1) in the membrane, with the aim to unravel the mechanisms and oxygenation dependencies of nitrite transport. Added nitrite rapidly diffused into the RBCs until equilibrium. The distribution ratio of nitrite across the membrane agreed with that expected from HNO2...... diffusion and AE1-mediated facilitated NO2- diffusion. Participation of HNO2 diffusion was emphasized by rapid transmembrane nitrite equilibration also in the natural AE1 knockouts. Following the equilibration, nitrite was consumed by reacting with Hb, which created a continued inward diffusion controlled...

  17. A Global Optimization Approach to Quantum Mechanics

    OpenAIRE

    Huang, Xiaofei

    2006-01-01

    This paper presents a global optimization approach to quantum mechanics, which describes the most fundamental dynamics of the universe. It suggests that the wave-like behavior of (sub)atomic particles could be the critical characteristic of a global optimization method deployed by nature so that (sub)atomic systems can find their ground states corresponding to the global minimum of some energy function associated with the system. The classic time-independent Schrodinger equation is shown to b...

  18. Isogeometric shape optimization in fluid mechanics

    DEFF Research Database (Denmark)

    Nørtoft, Peter; Gravesen, Jens

    2013-01-01

    , the steady-state, incompressible Navier-Stokes equations, governing a laminar flow in the domain, must be solved. Based on isogeometric analysis, we use B-splines as the basis for both the design optimization and the flow analysis, thereby unifying the models for geometry and analysis, and, at the same time......The subject of this work is numerical shape optimization in fluid mechanics, based on isogeometric analysis. The generic goal is to design the shape of a 2-dimensional flow domain to minimize some prescribed objective while satisfying given geometric constraints. As part of the design problem......, facilitating a compact representation of complex geometries and smooth approximations of the flow fields. To drive the shape optimization, we use a gradient-based approach, and to avoid inappropriate parametrizations during optimization, we regularize the optimization problem by adding to the objective...

  19. Structure and uptake mechanism of bacteriocins targeting peptidoglycan renewal.

    Science.gov (United States)

    Zeth, Kornelius

    2012-12-01

    Bacteriocins are narrow-spectrum protein antibiotics released to kill related bacteria of the same niche. Uptake of bacteriocins depends critically on the presence of an uptake receptor in the outer membrane, a translocation pore and an energy-dependent activating system of the inner membrane. Most bacteriocins act on the inner membrane as pore-forming toxins or they target cytoplasmic DNA/RNA and ribosomal synthesis respectively. Only two bacteriocins are known to become activated in the periplasmic space and to inhibit the renewal process of the peptidoglycan structure. In Escherichia coli, the Cma (colicin M) phosphatase is activated in the periplasmic space by the FkpA chaperone and subsequently degrades the C55-PP precursor unit of the peptidoglycan. Pst (pesticin) from Yersinia pestis carries a lysozyme homology domain to degrade peptidoglycan. Import of Pst is only achieved if the N-terminal translocation domain can span the outer membrane and if extensive unfolding of the protein during membrane passage is permitted. There is considerable plasticity in the import pathway since a chimaera comprising the activity domain replaced by T4 lysozyme is also translocated and active in killing those bacteria carrying the FyuA receptor.

  20. Impossibility of Differentially Private Universally Optimal Mechanisms

    CERN Document Server

    Brenner, Hai

    2010-01-01

    The notion of a universally utility-maximizing privacy mechanism was recently introduced by Ghosh, Roughgarden, and Sundararajan [STOC 2009]. These are mechanisms that guarantee optimal utility to a large class of information consumers, simultaneously, while preserving Differential Privacy [Dwork, McSherry, Nissim, and Smith, TCC 2006]. Ghosh et al. have demonstrated, quite surprisingly, a case where such a universally-optimal differentially-private mechanisms exists, when the information consumers are Bayesian. This result was recently extended by Gupte and Sundararajan [PODS 2010] to risk-averse consumers. Both positive results deal with mechanisms (approximately) computing a single count query (i.e., the number of individuals satisfying a specific property in a given population), and the starting point of our work is a trial at extending these results to similar settings, such as sum queries with non-binary individual values, histograms, and two (or more) count queries. We show, however, that universally-o...

  1. MECHANISMS AND OPTIMIZATION OF COAL COMBUSTION

    Energy Technology Data Exchange (ETDEWEB)

    Kyriacos Zygourakis

    1998-05-01

    We report the development of a novel experimental technique that combines video microscopy and thermogravimetric analysis to optimize the detection of coal and char particle ignitions. This technique is particularly effective for detecting ignitions occurring in coal or char samples containing multiple particles, where other commonly used techniques fail. The new approach also allows for visualization of ignition mechanism. Devolatilized char particles appear to ignite heterogeneously, while coal particles may ignite homogeneously, heterogeneously or through a combination of both mechanisms.

  2. Optimal Search Mechanism Analysis of Light Ray Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    Jihong SHEN; Jialian LI; Bin WEI

    2012-01-01

    Based on Fermat's principle and the automatic optimization mechanism in the propagation process of light,an optimal searching algorithm named light ray optimization is presented,where the laws of refraction and reflection of light rays are integrated into searching process of optimization.In this algorithm,coordinate space is assumed to be the space that is full of media with different refractivities,then the space is divided by grids,and finally the searching path is assumed to be the propagation path of light rays.With the law of refraction,the search direction is deflected to the direction that makes the value of objective function decrease.With the law of reflection,the search direction is changed,which makes the search continue when it cannot keep going with refraction.Only the function values of objective problems are used and there is no artificial rule in light ray optimization,so it is simple and easy to realize.Theoretical analysis and the results of numerical experiments show that the algorithm is feasible and effective.

  3. 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...

  4. Isogeometric shape optimization in fluid mechanics

    DEFF Research Database (Denmark)

    Nørtoft, Peter; Gravesen, Jens

    2013-01-01

    The subject of this work is numerical shape optimization in fluid mechanics, based on isogeometric analysis. The generic goal is to design the shape of a 2-dimensional flow domain to minimize some prescribed objective while satisfying given geometric constraints. As part of the design problem...

  5. Optimal allocation of building blocks between nutrient uptake systems in a microbe.

    Science.gov (United States)

    van den Berg, Hugo A; Kiselev, Yuri N; Orlov, Michael V

    2002-03-01

    A bacterial cell must distribute its molecular building blocks among various types of nutrient uptake systems. If the microbe is to maximize its average growth rate, this allocation of building blocks must be adjusted to the environmental availabilities of the various nutrients. The adjustments can be found from growth balancing considerations. We give a full proof of optimality and uniqueness of the optimal allocation regime for a simple model of microbial growth and internal stores kinetics. This proof suggests likely candidates for optimal control regimes in the case of a more realistic model. These candidate regimes differ with respect to the information that the cell's control system must have access to. We pay particular attention to one of the three candidates, a feedback regime based on a cellular control system that monitors only internal reserve densities. We show that allocation converges rapidly to balanced growth under this control regime.

  6. Biophysical response of living cells to boron nitride nanoparticles: uptake mechanism and bio-mechanical characterization

    Science.gov (United States)

    Rasel, Md. Alim Iftekhar; Li, Tong; Nguyen, Trung Dung; Singh, Sanjleena; Zhou, Yinghong; Xiao, Yin; Gu, YuanTong

    2015-11-01

    Boron nitride nanomaterials have attracted significant interest due to their superior chemical and physical properties. Despite these novel properties, investigation on the interaction between boron nitride nanoparticle (BN NP) and living systems has been limited. In this study, BN NP (100-250 nm) is assessed as a promising biomaterial for medical applications. The toxicity of BN NP is evaluated by assessing the cells behaviours both biologically (MTT assay, ROS detection etc.) and physically (atomic force microscopy). The uptake mechanism of BN NP is studied by analysing the alternations in cellular morphology based on cell imaging techniques. The results demonstrate in vitro cytocompatibility of BN NP with immense potential for use as an effective nanoparticle for various bio-medical applications.

  7. Biophysical response of living cells to boron nitride nanoparticles: uptake mechanism and bio-mechanical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rasel, Md. Alim Iftekhar; Li, Tong; Nguyen, Trung Dung; Singh, Sanjleena [Queensland University of Technology (QUT), School of Chemistry, Physics and Mechanical Engineering (Australia); Zhou, Yinghong; Xiao, Yin [Queensland University of Technology (QUT), Institute of Health and Biomedical Innovation (Australia); Gu, YuanTong, E-mail: yuantong.gu@qut.edu.au [Queensland University of Technology (QUT), School of Chemistry, Physics and Mechanical Engineering (Australia)

    2015-11-15

    Boron nitride nanomaterials have attracted significant interest due to their superior chemical and physical properties. Despite these novel properties, investigation on the interaction between boron nitride nanoparticle (BN NP) and living systems has been limited. In this study, BN NP (100–250 nm) is assessed as a promising biomaterial for medical applications. The toxicity of BN NP is evaluated by assessing the cells behaviours both biologically (MTT assay, ROS detection etc.) and physically (atomic force microscopy). The uptake mechanism of BN NP is studied by analysing the alternations in cellular morphology based on cell imaging techniques. The results demonstrate in vitro cytocompatibility of BN NP with immense potential for use as an effective nanoparticle for various bio-medical applications.

  8. Efficiency of (Revenue-)Optimal Mechanisms

    OpenAIRE

    Aggarwal, Gagan; Goel, Gagan; Mehta, Aranyak

    2009-01-01

    We compare the expected efficiency of revenue maximizing (or {\\em optimal}) mechanisms with that of efficiency maximizing ones. We show that the efficiency of the revenue maximizing mechanism for selling a single item with k + log_{e/(e-1)} k + 1 bidders is at least as much as the efficiency of the efficiency maximizing mechanism with k bidders, when bidder valuations are drawn i.i.d. from a Monotone Hazard Rate distribution. Surprisingly, we also show that this bound is tight within a small ...

  9. Optimization of a relativistic quantum mechanical engine

    Science.gov (United States)

    Peña, Francisco J.; Ferré, Michel; Orellana, P. A.; Rojas, René G.; Vargas, P.

    2016-08-01

    We present an optimal analysis for a quantum mechanical engine working between two energy baths within the framework of relativistic quantum mechanics, adopting a first-order correction. This quantum mechanical engine, with the direct energy leakage between the energy baths, consists of two adiabatic and two isoenergetic processes and uses a three-level system of two noninteracting fermions as its working substance. Assuming that the potential wall moves at a finite speed, we derive the expression of power output and, in particular, reproduce the expression for the efficiency at maximum power.

  10. Ceruloplasmin ferroxidase activity stimulates cellular iron uptake by a trivalent cation-specific transport mechanism

    Science.gov (United States)

    Attieh, Z. K.; Mukhopadhyay, C. K.; Seshadri, V.; Tripoulas, N. A.; Fox, P. L.

    1999-01-01

    The balance required to maintain appropriate cellular and tissue iron levels has led to the evolution of multiple mechanisms to precisely regulate iron uptake from transferrin and low molecular weight iron chelates. A role for ceruloplasmin (Cp) in vertebrate iron metabolism is suggested by its potent ferroxidase activity catalyzing conversion of Fe2+ to Fe3+, by identification of yeast copper oxidases homologous to Cp that facilitate high affinity iron uptake, and by studies of "aceruloplasminemic" patients who have extensive iron deposits in multiple tissues. We have recently shown that Cp increases iron uptake by cultured HepG2 cells. In this report, we investigated the mechanism by which Cp stimulates cellular iron uptake. Cp stimulated the rate of non-transferrin 55Fe uptake by iron-deficient K562 cells by 2-3-fold, using a transferrin receptor-independent pathway. Induction of Cp-stimulated iron uptake by iron deficiency was blocked by actinomycin D and cycloheximide, consistent with a transcriptionally induced or regulated transporter. Cp-stimulated iron uptake was completely blocked by unlabeled Fe3+ and by other trivalent cations including Al3+, Ga3+, and Cr3+, but not by divalent cations. These results indicate that Cp utilizes a trivalent cation-specific transporter. Cp ferroxidase activity was required for iron uptake as shown by the ineffectiveness of two ferroxidase-deficient Cp preparations, copper-deficient Cp and thiomolybdate-treated Cp. We propose a model in which iron reduction and subsequent re-oxidation by Cp are essential for an iron uptake pathway with high ion specificity.

  11. Metal uptake and acute toxicity in zebrafish: Common mechanisms across multiple metals

    Energy Technology Data Exchange (ETDEWEB)

    Alsop, Derek, E-mail: alsopde@mcmaster.ca [Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1 (Canada); Wood, Chris M. [Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1 (Canada)

    2011-10-15

    All metals tested reduced calcium uptake in zebrafish larvae. However, it was whole body sodium loss that was functionally related to toxicity. The zebrafish larvae acute toxicity assay save time, space and resources. - Abstract: Zebrafish larvae (Danio rerio) were used to examine the mechanisms of action and acute toxicities of metals. Larvae had similar physiological responses and sensitivities to waterborne metals as adults. While cadmium and zinc have previously been shown to reduce Ca{sup 2+} uptake, copper and nickel also decreased Ca{sup 2+} uptake, suggesting that the epithelial transport of all these metals is through Ca{sup 2+} pathways. However, exposure to cadmium, copper or nickel for up to 48 h had little or no effect on total whole body Ca{sup 2+} levels, indicating that the reduction of Ca{sup 2+} uptake is not the acute toxic mechanism of these metals. Instead, mortalities were effectively related to whole body Na{sup +}, which decreased up to 39% after 48 h exposures to different metals around their respective 96 h LC50s. Decreases in whole body K{sup +} were also observed, although they were not as pronounced or frequent as Na{sup +} losses. None of the metals tested inhibited Na{sup +} uptake in zebrafish (Na{sup +} uptake was in fact increased with exposure) and the observed losses of Na{sup +}, K{sup +}, Ca{sup 2+} and Mg{sup 2+} were proportional to the ionic gradients between the plasma and water, indicating diffusive ion loss with metal exposure. This study has shown that there is a common pathway for metal uptake and a common mechanism of acute toxicity across groups of metals in zebrafish. The disruption of ion uptake accompanying metal exposure does not appear to be responsible for the acute toxicity of metals, as has been previously suggested, but rather the toxicity is instead due to total ion loss (predominantly Na{sup +}).

  12. 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

  13. Energy Harvesting By Optimized Piezo Transduction Mechanism

    CERN Document Server

    Boban, Bijo; Satheesh, U; Devaprakasam, D

    2014-01-01

    We report generation of electrical energy from nonlinear mechanical noises available in the ambient environment using optimized piezo transduction mechanisms. Obtaining energy from an ambient vibration has been attractive for remotely installed standalone microsystems and devices. The mechanical noises in the ambient environment can be converted to electrical energy by a piezo strip based on the principle of piezoelectric effect. In this work, we have designed and developed a standalone energy harvesting module based on piezo transduction mechanisms. Using this designed module we harvested noise energy and stored electrical energy in a capacitor. Using NI-PXI workstation with a LabVIEW programming, the output voltage of the piezo strip and voltage of the capacitor were measured and monitored. In this paper we discuss about the design, development, implementation, performance and characteristics of the energy harvesting module.

  14. Mechanism of boron uptake by hydrocalumite calcined at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xinhong, E-mail: qxinhong@gmail.com [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Ideta, Keiko; Miyawaki, Jin [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8180 (Japan)

    2015-04-28

    Highlights: • Higher sorption density of borate was observed at higher calcination temperature. • Sorption of borate by Ca-Al-LDH was mainly through DR mechanism. • Removal of borate by Ca-LDH-300 and Ca-LDH-500 were through forming of ettringite. • Boron was mainly adsorbed and intercalated into hydration of Ca-Al-LDH-900. - Abstract: Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900 °C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by {sup 11}B NMR, {sup 27}Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution–reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500 °C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca{sup 2+} ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900 °C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO{sub 3}{sup 2−} into the interlayer, most the LDHs.

  15. Mechanism of boron uptake by hydrocalumite calcined at different temperatures.

    Science.gov (United States)

    Qiu, Xinhong; Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi; Ideta, Keiko; Miyawaki, Jin

    2015-04-28

    Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900°C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by (11)B NMR, (27)Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution-reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500°C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca(2+) ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900°C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO3(2-) into the interlayer, most the LDHs. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Copper speciation and isotopic fractionation in plants: uptake and translocation mechanisms.

    Science.gov (United States)

    Ryan, Brooke M; Kirby, Jason K; Degryse, Fien; Harris, Hugh; McLaughlin, Mike J; Scheiderich, Kathleen

    2013-07-01

    The fractionation of stable copper (Cu) isotopes during uptake into plant roots and translocation to shoots can provide information on Cu acquisition mechanisms. Isotope fractionation ((65) Cu/(63) Cu) and intact tissue speciation techniques (X-ray absorption spectroscopy, XAS) were used to examine the uptake, translocation and speciation of Cu in strategy I (tomato-Solanum lycopersicum) and strategy II (oat-Avena sativa) plant species. Plants were grown in controlled solution cultures, under varied iron (Fe) conditions, to test whether the stimulation of Fe-acquiring mechanisms can affect Cu uptake in plants. Isotopically light Cu was preferentially incorporated into tomatoes (Δ(65) Cu(whole plant-solution ) = c. -1‰), whereas oats showed minimal isotopic fractionation, with no effect of Fe supply in either species. The heavier isotope was preferentially translocated to shoots in tomato, whereas oat plants showed no significant fractionation during translocation. The majority of Cu in the roots and leaves of both species existed as sulfur-coordinated Cu(I) species resembling glutathione/cysteine-rich proteins. The presence of isotopically light Cu in tomatoes is attributed to a reductive uptake mechanism, and the isotopic shifts within various tissues are attributed to redox cycling during translocation. The lack of isotopic discrimination in oat plants suggests that Cu uptake and translocation are not redox selective.

  17. Uptake of ricinB-quantum dot nanoparticles by a macropinocytosis-like mechanism

    Directory of Open Access Journals (Sweden)

    Iversen Tore

    2012-07-01

    Full Text Available Abstract Background There is a huge effort in developing ligand-mediated targeting of nanoparticles to diseased cells and tissue. The plant toxin ricin has been shown to enter cells by utilizing both dynamin-dependent and -independent endocytic pathways. Thus, it is a representative ligand for addressing the important issue of whether even a relatively small ligand-nanoparticle conjugate can gain access to the same endocytic pathways as the free ligand. Results Here we present a systematic study concerning the internalization mechanism of ricinB:Quantum dot (QD nanoparticle conjugates in HeLa cells. Contrary to uptake of ricin itself, we found that internalization of ricinB:QDs was inhibited in HeLa cells expressing dominant-negative dynamin. Both clathrin-, Rho-dependent uptake as well as a specific form of macropinocytosis involve dynamin. However, the ricinB:QD uptake was not affected by siRNA-mediated knockdown of clathrin or inhibition of Rho-dependent uptake caused by treating cells with the Clostridium C3 transferase. RicinB:QD uptake was significantly reduced by cholesterol depletion with methyl-β-cyclodextrin and by inhibitors of actin polymerization such as cytochalasin D. Finally, we found that uptake of ricinB:QDs was blocked by the amiloride analog EIPA, an inhibitor of macropinocytosis. Upon entry, the ricinB:QDs co-localized with dextran, a marker for fluid-phase uptake. Thus, internalization of ricinB:QDs in HeLa cells critically relies on a dynamin-dependent macropinocytosis-like mechanism. Conclusions Our results demonstrate that internalization of a ligand-nanoparticle conjugate can be dependent on other endocytic mechanisms than those used by the free ligand, highlighting the challenges of using ligand-mediated targeting of nanoparticles-based drug delivery vehicles to cells of diseased tissues.

  18. Transferrin iron uptake is stimulated by ascorbate via an intracellular reductive mechanism.

    Science.gov (United States)

    Lane, Darius J R; Chikhani, Sherin; Richardson, Vera; Richardson, Des R

    2013-06-01

    Although ascorbate has long been known to stimulate dietary iron (Fe) absorption and non-transferrin Fe uptake, the role of ascorbate in transferrin Fe uptake is unknown. Transferrin is a serum Fe transport protein supplying almost all cellular Fe under physiological conditions. We sought to examine ascorbate's role in this process, particularly as cultured cells are typically ascorbate-deficient. At typical plasma concentrations, ascorbate significantly increased (59)Fe uptake from transferrin by 1.5-2-fold in a range of cells. Moreover, ascorbate enhanced ferritin expression and increased (59)Fe accumulation in ferritin. The lack of effect of cycloheximide or the cytosolic aconitase inhibitor, oxalomalate, on ascorbate-mediated (59)Fe uptake from transferrin indicate increased ferritin synthesis or cytosolic aconitase activity was not responsible for ascorbate's activity. Experiments with membrane-permeant and -impermeant ascorbate-oxidizing reagents indicate that while extracellular ascorbate is required for stimulation of (59)Fe uptake from (59)Fe-citrate, only intracellular ascorbate is needed for transferrin (59)Fe uptake. Additionally, experiments with l-ascorbate analogs indicate ascorbate's reducing ene-diol moiety is necessary for its stimulatory activity. Importantly, neither N-acetylcysteine nor buthionine sulfoximine, which increase or decrease intracellular glutathione, respectively, affected transferrin-dependent (59)Fe uptake. Thus, ascorbate's stimulatory effect is not due to a general increase in cellular reducing capacity. Ascorbate also did not affect expression of transferrin receptor 1 or (125)I-transferrin cellular flux. However, transferrin receptors, endocytosis, vacuolar-type ATPase activity and endosomal acidification were required for ascorbate's stimulatory activity. Therefore, ascorbate is a novel modulator of the classical transferrin Fe uptake pathway, acting via an intracellular reductive mechanism.

  19. Imaging TMS: antidepressant mechanisms and treatment optimization.

    Science.gov (United States)

    Dubin, Marc

    2017-04-01

    With the antidepressant efficacy of Transcranial Magnetic Stimulation well-established by several meta-analyses, there is growing interest in its mechanism of action. TMS has been shown to engage, and in some cases, normalize functional connectivity and neurotransmitter levels within networks dysfunctional in the depressed state. In this review, I will suggest candidate biomarkers, based on neuroimaging, that may be predictive of response to TMS. I will then review the effects of TMS on networks and neurotransmitter systems involved in depression. Throughout, I will also discuss how our current understanding of response predication and network engagement may be used to personalize treatment and optimize its efficacy.

  20. Multidisciplinary design optimization in computational mechanics

    CERN Document Server

    Breitkopf, Piotr

    2013-01-01

    This book provides a comprehensive introduction to the mathematical and algorithmic methods for the Multidisciplinary Design Optimization (MDO) of complex mechanical systems such as aircraft or car engines. We have focused on the presentation of strategies efficiently and economically managing the different levels of complexity in coupled disciplines (e.g. structure, fluid, thermal, acoustics, etc.), ranging from Reduced Order Models (ROM) to full-scale Finite Element (FE) or Finite Volume (FV) simulations. Particular focus is given to the uncertainty quantification and its impact on the robus

  1. Vitamin B12 uptake by intestinal microorganisms: mechanism and relevance to syndromes of intestinal bacterial overgrowth

    Science.gov (United States)

    Giannella, R. A.; Broitman, S. A.; Zamcheck, N.

    1971-01-01

    The mechanism of bacterial uptake of vitamin B12, the spectrum of microorganisms capable of such uptake, and the factors involved were the subject of this study. Bacterial uptake of vitamin B12 was found to be at least a two stage process. A primary uptake phase which was rapid (1 min or less), pH dependent, nontemperature dependent, did not require viable organisms and was insensitive to either the metabolic inhibitor dinitrophenol or to the sulfhydryl inhibitor N-ethyl-maleimide. Protein denaturation (formalin treatment or autoclaving) abolished all B12 uptake. This primary uptake phase is thought to represent adsorption to binding or “receptor” sites on the cell wall. Second stage uptake was slower, pH and temperature dependent, required living bacteria, and was abolished by either dinitrophenol or N-ethyl-maleimide. This phase is dependent upon metabolic processes and may reflect transfer of B12 from surface “receptor” sites into the bacterial cell. Although differences among organisms were observed in total 1 hr uptake, number of surface “receptor” sites, and relative avidities for B12, all organisms except Streptococcus fecalis shared the two stage mechanism. Two Gram-positive organisms. Bacillus subtilis and Group A streptococcus, demonstrated the highest 1 hr vitamin B12 uptake values; Gram-negative bacteria required 2,000-10,000 the number of organisms for comparable uptake. Binding constants (Km) varied from 5.05 ±1.67 × 10-10M for B. subtilis to 6.18 ±3.08 × 10-9M for Klebsiella pneumoniae which approximate the Km for human intrinsic factor (0.38 × 10-10M). Competition between bacteria and intrinsic factor for vitamin B12 may be inferred from the similarity of these constants. These observations suggest that a variety of enteric and nonenteric organisms, not requiring exogenous B12, may play a role in the pathogenesis of the vitamin B12 malabsorption found in the intestinal bacterial overgrowth syndromes. PMID:4994753

  2. The effect of water uptake on the mechanical properties of low-k organosilica glass

    Science.gov (United States)

    X. Guo; J.E. Jakes; M.T. Nichols; S. Banna; Y. Nishi; J.L. Shohet

    2013-01-01

    Water uptake in porous low-k dielectrics has become a significant challenge for both back-end-of line integration and circuit reliability. The influence of absorbed water on the mechanical properties of plasma-enhanced chemical-vapor-deposited organosilicate glasses (SiCOH) was investigated with nanoindentation. The roles of physisorbed (α-...

  3. Estimating plant water uptake source depths with optimized stable water isotope labeling

    Science.gov (United States)

    Seeger, Stefan; Weiler, Markus

    2016-04-01

    Depth profiles of pore water stable isotopes in soils in conjunction with measurements of stable water isotopes (SWI) in plant transpiration allow the estimation of the contributions of different soil depths to plant water uptake (PWU).
 However, SWI depth profiles that result from the variations of SWI in natural precipitation may lead to highly ambiguous results, i.e. the same SWI signature in transpiration could result from different PWU patterns or SWI depth profiles. The aim of this study was to find an optimal stable water isotope depth profile to estimate plant water uptake patterns and to compare different PWU source depth estimation methods. We used a new soil water transport model including fractionation effects of SWI and exchange between the vapor and liquid phase to simulate different irrigation scenarios. Different amounts of water with differing SWI signatures (glacier melt water, summer precipitation water, deuterated water) were applied in order to obtain a wide variety of SWI depth profiles. Based on these simulated SWI depth profiles and a set of hypothetical PWU patterns, the theoretical SWI signatures of the respective plant transpiration were computed. In the next step, two methods - Bayesian isotope mixing models (BIMs) and optimization of a parametric distribution function (beta function) - were used to estimate the PWU patterns from the different SWI depth profiles and their respective SWI signatures in the resulting transpiration. Eventually, the estimated and computed profiles were compared to find the best SWI depth profile and the best method. The results showed, that compared to naturally occurring SWI depth profiles, the application of multiple, in terms of SWI, distinct labeling pulses greatly improves the possible spatial resolution and at the same time reduces the uncertainty of PWU estimates.
 For the PWU patterns which were assumed for this study, PWU pattern estimates based on an optimized parametric distribution function

  4. The biocompatibility of fluorescent nanodiamonds and their mechanism of cellular uptake

    Energy Technology Data Exchange (ETDEWEB)

    Vaijayanthimala, Vairakkannu; Tzeng, Yan-Kai; Chang, Huan-Cheng [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Li, Chung-Leung, E-mail: hcchang@po.sinica.edu.t, E-mail: chungL@gate.sinica.edu.t [Genomics Research Center, Academia Sinica, Taipei 115, Taiwan (China)

    2009-10-21

    The labeling of cells with fluorescent nanoparticles is promising for various biomedical applications. The objective of this study is to evaluate the biocompatibility and the mechanism of the cellular uptake of fluorescent nanodiamonds (FNDs) in cancer cells (HeLa) and pre-adipocytes (3T3-L1). With flow cytometry and the use of a battery of metabolic and cytoskeletal inhibitors, we found that the mechanism of the FND uptake in both cells is by energy-dependent clathrin-mediated endocytosis. In addition, the surface charge of FND influences its cellular uptake, as the uptake of poly-L-lysine-coated FNDs is better than that of oxidative-acid-purified FNDs at the same concentration in regular medium with or without serum. We also confirm that the proliferative potential of FND-treated and untreated cells does not exhibit any significant differences when measured at bulk cultures, and more stringently at clonal cell density. Further biocompatibility studies indicate that the in vitro differentiation of 3T3-L1 pre-adipocytes and 489-2 osteoprogenitors is not affected by the FND treatment. Our results show that FNDs are biocompatible and ideal candidates for potential applications in human stem cell research.

  5. Research on generalized optimization process for mechanical product

    Institute of Scientific and Technical Information of China (English)

    冯培恩; 邱清盈; 潘双夏; 董黎刚; 李善春

    1999-01-01

    The generalized optimization process for mechanical product is proposed which includes functional optimization phase, conceptual design optimization phase, technical design optimization phase (that is further divided into product modeling phase, optimization process scheduling phase, optimization modeling phase and multi-computer collaborative optimizing phase), and result analysis and evaluation phase. The characteristics of the generalized optimization are incarnated such as oriented to the design of entire system, whole process and overall performance of a product and combined with human intelligent and artificial intelligent optimization. The functions and the achieved strategies of each key phase in the generalized optimization process are discussed. A prototype of the generalized optimization supported system for mechanical product is preliminarily established.

  6. Decreased glucose uptake by hyperglycemia is regulated by different mechanisms in human cancer cells and monocytes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chae Kyun; Chung, June Key; Lee, Yong Jin; Hong, Mee Kyoung; Jeong, Jae Min; Lee, Dong Soo; Lee, Myung Chul [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

    2002-04-01

    To clarify the difference in glucose uptake between human cancer cells and monocytes, we studied ({sup 18}F) fluorodeoxyglucose (FDG) uptake in three human colon cancer cell lines (SNU-C2A, SNU-C4, SNU-C5), one human lung cancer cell line (NCI-H522), and human peripheral blood monocytes. The FDG uptake of both cancer cells and monocytes was increased in glucose-free medium, but decreased in the medium containing 16.7 mM glucose (hyperglycemic). The level of Glut1 mRNA decreased in human colon cancer cells and NCI-H522 under hyperglycemic condition. Glut1 protein expression was also decreased in the four human cancer cell lines under hyperglycemic condition, whereas it was consistently undetectable in monocytes. SNU-C2A, SNU-C4 and NCI-H522 showed a similar level of hexokinase activity (7.5-10.8 mU/mg), while SNU-C5 and moncytes showed lower range of hexokinase activity (4.3-6.5 mU/mg). These data suggest that glucose uptake is regulated by different mechanisms in human cancer cells and monocytes.

  7. Effect of Three Statins on Glucose Uptake of Cardiomyocytes and its Mechanism.

    Science.gov (United States)

    Jiang, Zhenhuan; Yu, Bo; Li, Yang

    2016-08-11

    BACKGROUND The aim of this study was to investigate the effects of different statins on glucose uptake and to confirm its mechanism in primary cultured rat cardiomyocytes after administration of atorvastatin, pravastatin, and rosuvastatin. MATERIAL AND METHODS Primary cultured rat cardiomyocytes were randomly assigned to 5 groups: normal control group (OB), insulin group (S1), statin 1-μM (S2), 5-μM (S3), and 10-μM (S4) groups for 3 different statins. The 2-[3H]-DG uptake of each group was determined and the mRNA and protein expression levels of glucose transporter type 4 (GLUT4), insulin receptor substrate (IRs), and RhoA were assessed. RESULTS After treatment with different concentrations of statins and insulin, the 2-[3H]-DG uptake showed a significant negative correlation with the concentration of atorvastatin (Pstatins. CONCLUSIONS These results confirm that atorvastatin can inhibit insulin-induced glucose uptake in primary cultured rat cardiomyocytes by regulating the PI3K/Akt insulin signal transduction pathway.

  8. The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble

    Directory of Open Access Journals (Sweden)

    P. R. Halloran

    2014-10-01

    vary rapidly. Given the importance of this sink and its apparent variability, it is critical that we understand the mechanisms behind its operation. Here we explore subpolar North Atlantic CO2 uptake across a large ensemble of Earth System Model simulations, and find that models show a peak in sink strength around the middle of the century after which CO2 uptake begins to decline. We identify different drivers of change on interannual and multidecadal timescales. Short-term variability appears to be driven by fluctuations in regional seawater temperature and alkalinity, whereas the longer-term evolution throughout the coming century is largely occurring through a counterintuitive response to rising atmospheric CO2 concentrations. At high atmospheric CO2 concentrations the contrasting Ravelle factors between the subtropical and subpolar gyres, combined with the transport of surface waters from the subtropical to subpolar gyre, means that the subpolar CO2 uptake capacity is largely satisfied from its southern boundary rather than through air–sea CO2 flux. Our findings indicate that: (i we can explain the mechanisms of subpolar North Atlantic CO2 uptake variability across a broad range of Earth System Models, (ii a focus on understanding the mechanisms behind contemporary variability may not directly tell us about how the sink will change in the future, (iii to identify long-term change in the North Atlantic CO2 sink we should focus observational resources on monitoring subtropical as well as the subpolar seawater CO2, (iv recent observations of a weakening subpolar North Atlantic CO2 sink suggests that the sink strength is already in long-term decline.

  9. Growth and nitrogen uptake characteristics reveal outbreak mechanism of the opportunistic macroalga Gracilaria tenuistipitata.

    Directory of Open Access Journals (Sweden)

    Chao Wang

    Full Text Available Macroalgae has bloomed in the brackish lake of Shenzhen Bay, China continuously from 2010 to 2014. Gracilaria tenuistipitata was identified as the causative macroalgal species. The aim of this study was to explore the outbreak mechanism of G. tenuistipitata, by studying the effects of salinity and nitrogen sources on growth, and the different nitrogen sources uptake characteristic. Our experimental design was based on environmental conditions observed in the bloom areas, and these main factors were simulated in the laboratory. Results showed that salinity 12 to 20 ‰ was suitable for G. tenuistipitata growth. When the nitrogen sources' (NH4+, NO3- concentrations reached 40 µM or above, the growth rate of G. tenuistipitata was significantly higher. Algal biomass was higher (approximately 1.4 times when cultured with NH4+ than that with NO3- addition. Coincidentally, macroalgal bloom formed during times of moderate salinity (∼12 ‰ and high nitrogen conditions. The NH4+ and NO3- uptake characteristic was studied to understand the potential mechanism of G. tenuistipitata bloom. NH4+ uptake was best described by a linear, rate-unsaturated response, with the slope decreasing with time intervals. In contrast, NO3- uptake followed a rate-saturating mechanism best described by the Michaelis-Menten model, with kinetic parameters Vmax = 37.2 µM g-1 DM h-1 and Ks = 61.5 µM. Further, based on the isotope 15N tracer method, we found that 15N from NH4+ accumulated faster and reached an atom% twice than that of 15N from NO3-, suggesting when both NH4+ and NO3- were available, NH4+ was assimilated more rapidly. The results of the present study indicate that in the estuarine environment, the combination of moderate salinity with high ammonium may stimulate bloom formation.

  10. Growth and nitrogen uptake characteristics reveal outbreak mechanism of the opportunistic macroalga Gracilaria tenuistipitata.

    Science.gov (United States)

    Wang, Chao; Lei, Anping; Zhou, Kai; Hu, Zhengyu; Hao, Wenlong; Yang, Junda

    2014-01-01

    Macroalgae has bloomed in the brackish lake of Shenzhen Bay, China continuously from 2010 to 2014. Gracilaria tenuistipitata was identified as the causative macroalgal species. The aim of this study was to explore the outbreak mechanism of G. tenuistipitata, by studying the effects of salinity and nitrogen sources on growth, and the different nitrogen sources uptake characteristic. Our experimental design was based on environmental conditions observed in the bloom areas, and these main factors were simulated in the laboratory. Results showed that salinity 12 to 20 ‰ was suitable for G. tenuistipitata growth. When the nitrogen sources' (NH4+, NO3-) concentrations reached 40 µM or above, the growth rate of G. tenuistipitata was significantly higher. Algal biomass was higher (approximately 1.4 times) when cultured with NH4+ than that with NO3- addition. Coincidentally, macroalgal bloom formed during times of moderate salinity (∼12 ‰) and high nitrogen conditions. The NH4+ and NO3- uptake characteristic was studied to understand the potential mechanism of G. tenuistipitata bloom. NH4+ uptake was best described by a linear, rate-unsaturated response, with the slope decreasing with time intervals. In contrast, NO3- uptake followed a rate-saturating mechanism best described by the Michaelis-Menten model, with kinetic parameters Vmax = 37.2 µM g-1 DM h-1 and Ks = 61.5 µM. Further, based on the isotope 15N tracer method, we found that 15N from NH4+ accumulated faster and reached an atom% twice than that of 15N from NO3-, suggesting when both NH4+ and NO3- were available, NH4+ was assimilated more rapidly. The results of the present study indicate that in the estuarine environment, the combination of moderate salinity with high ammonium may stimulate bloom formation.

  11. Chronic alcohol exposure inhibits biotin uptake by pancreatic acinar cells: possible involvement of epigenetic mechanisms.

    Science.gov (United States)

    Srinivasan, Padmanabhan; Kapadia, Rubina; Biswas, Arundhati; Said, Hamid M

    2014-11-01

    Chronic exposure to alcohol affects different physiological aspects of pancreatic acinar cells (PAC), but its effect on the uptake process of biotin is not known. We addressed this issue using mouse-derived pancreatic acinar 266-6 cells chronically exposed to alcohol and wild-type and transgenic mice (carrying the human SLC5A6 5'-promoter) fed alcohol chronically. First we established that biotin uptake by PAC is Na(+) dependent and carrier mediated and involves sodium-dependent multivitamin transporter (SMVT). Chronic exposure of 266-6 cells to alcohol led to a significant inhibition in biotin uptake, expression of SMVT protein, and mRNA as well as in the activity of the SLC5A6 promoter. Similarly, chronic alcohol feeding of wild-type and transgenic mice carrying the SLC5A6 promoter led to a significant inhibition in biotin uptake by PAC, as well as in the expression of SMVT protein and mRNA and the activity of the SLC5A6 promoters expressed in the transgenic mice. We also found that chronic alcohol feeding of mice is associated with a significant increase in the methylation status of CpG islands predicted to be in the mouse Slc5a6 promoters and a decrease in the level of expression of transcription factor KLF-4, which plays an important role in regulating SLC5A6 promoter activity. These results demonstrate, for the first time, that chronic alcohol exposure negatively impacts biotin uptake in PAC and that this effect is exerted (at least in part) at the level of transcription of the SLC5A6 gene and may involve epigenetic/molecular mechanisms.

  12. On a Variational Approach to Optimization of Hybrid Mechanical Systems

    Directory of Open Access Journals (Sweden)

    Vadim Azhmyakov

    2010-01-01

    Full Text Available This paper deals with multiobjective optimization techniques for a class of hybrid optimal control problems in mechanical systems. We deal with general nonlinear hybrid control systems described by boundary-value problems associated with hybrid-type Euler-Lagrange or Hamilton equations. The variational structure of the corresponding solutions makes it possible to reduce the original “mechanical” problem to an auxiliary multiobjective programming reformulation. This approach motivates possible applications of theoretical and computational results from multiobjective optimization related to the original dynamical optimization problem. We consider first order optimality conditions for optimal control problems governed by hybrid mechanical systems and also discuss some conceptual algorithms.

  13. An optimization method for metamorphic mechanisms based on multidisciplinary design optimization

    Directory of Open Access Journals (Sweden)

    Zhang Wuxiang

    2014-12-01

    Full Text Available The optimization of metamorphic mechanisms is different from that of the conventional mechanisms for its characteristics of multi-configuration. There exist complex coupled design variables and constraints in its multiple different configuration optimization models. To achieve the compatible optimized results of these coupled design variables, an optimization method for metamorphic mechanisms is developed in the paper based on the principle of multidisciplinary design optimization (MDO. Firstly, the optimization characteristics of the metamorphic mechanism are summarized distinctly by proposing the classification of design variables and constraints as well as coupling interactions among its different configuration optimization models. Further, collaborative optimization technique which is used in MDO is adopted for achieving the overall optimization performance. The whole optimization process is then proposed by constructing a two-level hierarchical scheme with global optimizer and configuration optimizer loops. The method is demonstrated by optimizing a planar five-bar metamorphic mechanism which has two configurations, and results show that it can achieve coordinated optimization results for the same parameters in different configuration optimization models.

  14. An optimization method for metamorphic mechanisms based on multidisciplinary design optimization

    Institute of Scientific and Technical Information of China (English)

    Zhang Wuxiang; Wu Teng; Ding Xilun

    2014-01-01

    The optimization of metamorphic mechanisms is different from that of the conventional mechanisms for its characteristics of multi-configuration. There exist complex coupled design vari-ables and constraints in its multiple different configuration optimization models. To achieve the compatible optimized results of these coupled design variables, an optimization method for meta-morphic mechanisms is developed in the paper based on the principle of multidisciplinary design optimization (MDO). Firstly, the optimization characteristics of the metamorphic mechanism are summarized distinctly by proposing the classification of design variables and constraints as well as coupling interactions among its different configuration optimization models. Further, collabora-tive optimization technique which is used in MDO is adopted for achieving the overall optimization performance. The whole optimization process is then proposed by constructing a two-level hierar-chical scheme with global optimizer and configuration optimizer loops. The method is demon-strated by optimizing a planar five-bar metamorphic mechanism which has two configurations, and results show that it can achieve coordinated optimization results for the same parameters in different configuration optimization models.

  15. Evaluations of Mechanisms for Pu Uptake and Retention within Spherical Resorcinol-Formaldehyde Resin Columns

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Levitskaia, Tatiana G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fiskum, Sandra K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-15

    The unexpected uptake and retention of plutonium (Pu) onto columns containing spherical resorcinol-formaldehyde (sRF) resin during ion exchange testing of Cs (Cs) removal from alkaline tank waste was observed in experiments at both the Pacific Northwest National Laboratory (PNNL) and the Savannah River National Laboratory (SRNL). These observations have raised concern regarding the criticality safety of the Cs removal unit operation within the low-activity waste pretreatment system (LAWPS). Accordingly, studies have been initiated at Washington River Protection Solutions (WRPS), who manages the operations of the Hanford Site tank farms, including the LAWPS, PNNL, and elsewhere to investigate these findings. As part of these efforts, PNNL has prepared the present report to summarize the laboratory testing observations, evaluate these phenomena in light of published and unpublished technical information, and outline future laboratory testing, as deemed appropriate based on the literature studies, with the goal to elucidate the mechanisms for the observed Pu uptake and retention.

  16. Arsenic in hydrothermal apatite: Oxidation state, mechanism of uptake, and comparison between experiments and nature

    Science.gov (United States)

    Liu, Weihua; Mei, Yuan; Etschmann, Barbara; Brugger, Joël; Pearce, Mark; Ryan, Chris G.; Borg, Stacey; Wykes, Jeremey; Kappen, Peter; Paterson, David; Boesenberg, Ulrike; Garrevoet, Jan; Moorhead, Gareth; Falkenberg, Gerald

    2017-01-01

    expected to be the dominant As form in hydrothermal fluids. These results show that incorporation of As in apatite is a complicated process, and sensitive to the local fluid composition during crystallization, and that some of the complexity in As zoning in partially reacted apatite may be due to local fluctuations of As(V)/As(III) ratios in the fluid and to kinetic effects during the mineral replacement reaction. Our study shows for the first time that As(III) can be incorporated into the apatite structure, although not as efficiently as As(V). Uptake of As(III) is probably highly dependent on the reaction mechanism. As(III)O33- moieties replace phosphate groups, but cause a high strain on the lattice; as a result, As(III) is easily exchanged (or oxidized) for As(V) during hydrothermal recrystallization, and the fully reacted grains only record the preferred oxidation state (i.e., As(V)) from mixed-oxidation state solutions. Overall this study shows that the observed oxidation state of As in apatite may not reflect the original As(III)/As(V) ratio of the parent fluid, due to the complex nature of As(III) uptake and possible in situ oxidation during recrystallization.

  17. Maximizing opto‐mechanical interaction using topology optimization

    DEFF Research Database (Denmark)

    Gersborg, Allan Roulund; Sigmund, Ole

    2011-01-01

    This paper studies topology optimization of a coupled opto‐mechanical problem with the goal of finding the material layout which maximizes the optical modulation, i.e. the difference between the optical response for the mechanically deformed and undeformed configuration. The optimization is perfo......This paper studies topology optimization of a coupled opto‐mechanical problem with the goal of finding the material layout which maximizes the optical modulation, i.e. the difference between the optical response for the mechanically deformed and undeformed configuration. The optimization...

  18. Usage of the particle swarm optimization in problems of mechanics

    Directory of Open Access Journals (Sweden)

    Hajžman M.

    2016-06-01

    Full Text Available This paper deals with the optimization method called particle swarm optimization and its usage in mechanics. Basic versions of the method is introduced and several improvements and modifications are applied for better convergence of the algorithms. The performance of the optimization algorithm implemented in an original in-house software is investigated by means of three basic and one complex problems of mechanics. The goal of the first problem is to find optimal parameters of a dynamic absorber of vibrations. The second problem is about the tunning of eigenfrequencies of beam bending vibrations. The third problem is to optimize parameters of a clamped beam with various segments. The last complex problem is the optimization of a tilting mechanism with multilevel control. The presented results show that the particle swarm optimization can be efficiently used in mechanical tasks.

  19. 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.

  20. Optimized ground coupled heat pump mechanical package

    Energy Technology Data Exchange (ETDEWEB)

    Catan, M.A.

    1984-01-01

    The system which was optimized was a horizontal earth coil in a given house in the Pittsburgh area. The types of components used in the heat pump are essentially conventional. The method of this study is derived from one used to optimize an air-source heat pump for operation at standard steady state conditions. A computer model, created at Oak Ridge National Laboratory (ORNL), is used to predict heat pump performance for specified configuration and operating conditions. A predetermined set of design parameters is automatically altered by a constrained minimization program (a Numerical Algorithms Group library routine hereafter referred to as the optimizer) to find the combination for which the highest COP is predicted by the heat pump model. In the present study, the set of parameters to be varied include some pertaining to the ground coil as well as some pertaining to the heat pump. The optimizer, in this case, pursues a minimum life cycle cost which is calculated using the heat pump model, a ground coil model (called FTECM for Fast Transient Earth Coil model), and a parameterized cost model. The flow chart shows how the optimizer interacts with these programs to minimize life cycle cost.

  1. Uptake Mechanisms of Eu(III) on Hydroxyapatite: A Potential Permeable Reactive Barrier Backfill Material for Trapping Trivalent Minor Actinides.

    Science.gov (United States)

    Xu, Lin; Zheng, Tao; Yang, Shitong; Zhang, Linjuan; Wang, Jianqiang; Liu, Wei; Chen, Lanhua; Diwu, Juan; Chai, Zhifang; Wang, Shuao

    2016-04-05

    The permeable reactive barrier (PRB) technique has attracted an increasing level of attention for the in situ remediation of contaminated groundwater. In this study, the macroscopic uptake behaviors and microscopic speciation of Eu(III) on hydroxyapatite (HAP) were investigated by a combination of theoretical modeling, batch experiments, powder X-ray diffraction (PXRD) fitting, and X-ray absorption spectroscopy (XAS). The underlying removal mechanisms were identified to further assess the application potential of HAP as an effective PRB backfill material. The macroscopic analysis revealed that nearly all dissolved Eu(III) in solution was removed at pH 6.5 within an extremely short reaction time of 5 min. In addition, the thermodynamic calculations, desorption experiments, and PXRD and XAS analyses definitely confirmed the formation of the EuPO4·H2O(s) phase during the process of uptake of dissolved Eu(III) by HAP via the dissolution-precipitation mechanism. A detailed comparison of the present experimental findings and related HAP-metal systems suggests that the relative contribution of precipitation to the total Eu(III) removal increases as the P:Eu ratio decreases. The dosage of HAP-based PRB for the remediation of groundwater polluted by Eu(III) and analogous trivalent actinides [e.g., Am(III) and Cm(III)] should be strictly controlled depending on the dissolved Eu(III) concentration to obtain an optimal P:M (M represents Eu, Am, or Cm) ratio and treatment efficiency.

  2. A minimal model for the mitochondrial rapid mode of Ca²+ uptake mechanism.

    Directory of Open Access Journals (Sweden)

    Jason N Bazil

    Full Text Available Mitochondria possess a remarkable ability to rapidly accumulate and sequester Ca²⁺. One of the mechanisms responsible for this ability is believed to be the rapid mode (RaM of Ca²⁺ uptake. Despite the existence of many models of mitochondrial Ca²⁺ dynamics, very few consider RaM as a potential mechanism that regulates mitochondrial Ca²⁺ dynamics. To fill this gap, a novel mathematical model of the RaM mechanism is developed herein. The model is able to simulate the available experimental data of rapid Ca²⁺ uptake in isolated mitochondria from both chicken heart and rat liver tissues with good fidelity. The mechanism is based on Ca²⁺ binding to an external trigger site(s and initiating a brief transient of high Ca²⁺ conductivity. It then quickly switches to an inhibited, zero-conductive state until the external Ca²⁺ level is dropped below a critical value (∼100-150 nM. RaM's Ca²⁺- and time-dependent properties make it a unique Ca²⁺ transporter that may be an important means by which mitochondria take up Ca²⁺ in situ and help enable mitochondria to decode cytosolic Ca²⁺ signals. Integrating the developed RaM model into existing models of mitochondrial Ca²⁺ dynamics will help elucidate the physiological role that this unique mechanism plays in mitochondrial Ca²⁺-homeostasis and bioenergetics.

  3. A systems toxicology approach on the mechanism of uptake and toxicity of MWCNT in Caenorhabditis elegans.

    Science.gov (United States)

    Eom, Hyun-Jeong; Roca, Carlos P; Roh, Ji-Yeon; Chatterjee, Nivedita; Jeong, Jae-Seong; Shim, Ilseob; Kim, Hyun-Mi; Kim, Phil-Je; Choi, Kyunghee; Giralt, Francesc; Choi, Jinhee

    2015-09-01

    The increased volumes of carbon nanotubes (CNTs) being utilized in industrial and biomedical processes carries with it an increased risk of unintentional release into the environment, requiring a thorough hazard and risk assessment. In this study, the toxicity of pristine and hydroxylated (OH-) multiwall CNTs (MWCNTs) was investigated in the nematode Caenorhabditis elegans using an integrated systems toxicology approach. To gain an insight into the toxic mechanism of MWCNTs, microarray and proteomics were conducted for C. elegans followed by pathway analyses. The results of pathway analyses suggested endocytosis, phagocytosis, oxidative stress and endoplasmic reticulum (ER) stress, as potential mechanisms of uptake and toxicity, which were subsequently investigated using loss-of-function mutants of genes of those pathways. The expression of phagocytosis related genes (i.e. ced-10 and rab-7) were significantly increased upon exposure to OH-MWCNT, concomitantly with the rescued toxicity by loss-of-function mutants of those genes, such as ced-10(n3246) and rab-7(ok511). An increased sensitivity of the hsp-4(gk514) mutant by OH-MWCNT, along with a decreased expression of hsp-4 at both gene and protein level suggests that MWCNTs may affect ER stress response in C. elegans. Collectively, the results implied phagocytosis to be a potential mechanism of uptake of MWCNTs, and ER and oxidative stress as potential mechanisms of toxicity. The integrated systems toxicology approach applied in this study provided a comprehensive insight into the toxic mechanism of MWCNTs in C. elegans, which may eventually be used to develop an "Adverse Outcome Pathway (AOP)", a recently introduced concept as a conceptual framework to link molecular level responses to higher level effects.

  4. A minimal model for the mitochondrial rapid mode of Ca²+ uptake mechanism.

    Science.gov (United States)

    Bazil, Jason N; Dash, Ranjan K

    2011-01-01

    Mitochondria possess a remarkable ability to rapidly accumulate and sequester Ca²⁺. One of the mechanisms responsible for this ability is believed to be the rapid mode (RaM) of Ca²⁺ uptake. Despite the existence of many models of mitochondrial Ca²⁺ dynamics, very few consider RaM as a potential mechanism that regulates mitochondrial Ca²⁺ dynamics. To fill this gap, a novel mathematical model of the RaM mechanism is developed herein. The model is able to simulate the available experimental data of rapid Ca²⁺ uptake in isolated mitochondria from both chicken heart and rat liver tissues with good fidelity. The mechanism is based on Ca²⁺ binding to an external trigger site(s) and initiating a brief transient of high Ca²⁺ conductivity. It then quickly switches to an inhibited, zero-conductive state until the external Ca²⁺ level is dropped below a critical value (∼100-150 nM). RaM's Ca²⁺- and time-dependent properties make it a unique Ca²⁺ transporter that may be an important means by which mitochondria take up Ca²⁺ in situ and help enable mitochondria to decode cytosolic Ca²⁺ signals. Integrating the developed RaM model into existing models of mitochondrial Ca²⁺ dynamics will help elucidate the physiological role that this unique mechanism plays in mitochondrial Ca²⁺-homeostasis and bioenergetics.

  5. Effects of high NH4+ on K+ uptake, culm mechanical strength and grain filling in wheat

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    Lingan eKong

    2014-12-01

    Full Text Available It is well established that a high external NH4+ concentration depresses many processes in plant development, but the underlying mechanisms are still not well understood. To determine whether the negative effects of high levels of NH4+ are related to competitive cation uptake, wheat was grown in a field with moderate (18 g N m-2 and high (30 g N m-2 supplies of NH4+ in the presence or absence of additional K+ (6 g K2O m-2 to examine culm mechanical strength, the main components of the vascular bundle, nitrogen (N remobilization and the grain-filling rate. The results indicated that an excessive supply of NH4+ significantly decreased culm mechanical strength, the cellulose and lignin contents of vascular bundles, the N remobilization efficiency (NRE and the grain-filling rate compared with a moderate level of NH4+. The additional provision of K+ considerably alleviated these negative effects of high NH4+, resulting in a 19.41%-26.95% increase in culm mechanical strength during grain filling and a 34.59% increase in the NRE. An assay using the scanning ion-selective electrode technique (SIET showed that the net rate of transmembrane K+ influx decreased by 84.62%, and measurements using flame photometry demonstrated that the K+ content decreased by 36.13% in wheat plants subjected to high NH4+. This study indicates that the effects of high NH4+ on culm mechanical strength, cellulose and lignin contents, the NRE and the grain-filling rate are probably associated with inhibition of K+ uptake in wheat.

  6. Action Mechanisms of Arbuscular Mycorrhizal Fungi in Phosphorus Uptake by Capsicum annuum L.

    Institute of Scientific and Technical Information of China (English)

    M. SHARIF; N. CLAASSEN

    2011-01-01

    A pot experiment was conducted to investigate the action mechanisms of arbuscular mycorrhizal (AM) fungi in phosphorus (P) uptake of Capsicum annuum L.in a sterilized fossil Oxisol. Three P levels of 0,10 and 200 mg kg-1 soil (P0,P10 and P200,respectively) without and with AM fungal inoculation were applied as Ca(H2PO4)2·H2O.Shoot dry matter yields and shoot P uptake increased significantly (P > 0.05) by the inoculation of AM fungi at P0 and P10.Root length and P concentration in soil solution increased with the inoculation of AM fungi but the root:shoot ratio decreased or remained constant.Around 50% roots of inoculated plants were infected by AM and the external hyphae amounted to 20 m g-1 soil at P10 and P200.The hyphae surface area of the infected root cylinder amounted to 11 and 2 cm2 cm-2 root at P0 and P10,respectively.The increased P uptake of inoculated plants was mainly because of an up to 5 times higher P influx of the infected root.Model calculations showed that the root alone could not have achieved the measured P influx in both infected and non-infected roots.But the P influx for hyphae calculated by the model was even much higher than the measured one.The P uptake capacity of hyphae introduced in the model was too high.Model calculations further showed that the depletion zone around roots or hyphae was very narrow.In the case of the root only 7% of the soil volume would contribute P to the plant,while in the case of hyphae it would be 100%.The results together with the model calculations showed that the increased P uptake of AM inoculated plants could be explained partly by the increased P concentration in the soil solution and by the increased P absorbing surface area coming from the external hyphae.

  7. Saffron (Crocus sativus L.) increases glucose uptake and insulin sensitivity in muscle cells via multipathway mechanisms.

    Science.gov (United States)

    Kang, Changkeun; Lee, Hyunkyoung; Jung, Eun-Sun; Seyedian, Ramin; Jo, MiNa; Kim, Jehein; Kim, Jong-Shu; Kim, Euikyung

    2012-12-15

    Saffron (Crocus sativus Linn.) has been an important subject of research in the past two decades because of its various biological properties, including anti-cancer, anti-inflammatory, and anti-atherosclerotic activities. On the other hand, the molecular bases of its actions have been scarcely understood. Here, we elucidated the mechanism of the hypoglycemic actions of saffron through investigating its signaling pathways associated with glucose metabolism in C(2)C(12) skeletal muscle cells. Saffron strongly enhanced glucose uptake and the phosphorylation of AMPK (AMP-activated protein kinase)/ACC (acetyl-CoA carboxylase) and MAPKs (mitogen-activated protein kinases), but not PI 3-kinase (Phosphatidylinositol 3-kinase)/Akt. Interestingly, the co-treatment of saffron and insulin further improved the insulin sensitivity via both insulin-independent (AMPK/ACC and MAPKs) and insulin-dependent (PI 3-kinase/Akt and mTOR) pathways. It also suggested that there is a crosstalk between the two signaling pathways of glucose metabolism in skeletal muscle cells. These results could be confirmed from the findings of GLUT4 translocation. Taken together, AMPK plays a major role in the effects of saffron on glucose uptake and insulin sensitivity in skeletal muscle cells. Our study provides important insights for the possible mechanism of action of saffron and its potential as a therapeutic agent in diabetic patients.

  8. Mechanism of oil uptake during deep-fat frying and the surfactant effect-theory and myth.

    Science.gov (United States)

    Dana, Dina; Saguy, I Sam

    2006-12-21

    Three mechanisms have been previously proposed to explain the complex process of oil uptake during deep-fat frying. The mechanisms reviewed are water replacement, cooling-phase effect and surface-active agents. The former mechanism describes mainly oil uptake of relatively large voids in the fried food created due to water evaporation. The second mechanism furnishes an explanation for the significant amount of oil absorbed when the food is removed from the fryer. At this point, product surface characteristics and oil viscosity play paramount roles. Surface-active agents' formation provides only a limited explanation for the increased oil uptake during prolonged frying. Reviewed literature, theory and new data show contradicting values and do not support the myth that during extended frying time the surfactants generated reduce the contact angle and/or the interfacial tension, and consequently, influence oil uptake significantly. Higher oil uptake after extended frying time is probably related to higher oil viscosity caused by polymerization reactions and oil adherence to the product surface. Further research is needed for establishing the interrelationships between surface-active agents' formation and their effect on fried product oil uptake and quality to resolve this myth.

  9. Topology optimization in structural and continuum mechanics

    CERN Document Server

    Lewiński, Tomasz

    2014-01-01

    The book covers new developments in structural topology optimization. Basic features and limitations of Michell’s truss theory, its extension to a broader class of support conditions, generalizations of truss topology optimization, and Michell continua are reviewed. For elastic bodies, the layout problems in linear elasticity are discussed and the method of relaxation by homogenization is outlined. The classical problem of free material design is shown to be reducible to a locking material problem, even in the multiload case. For structures subjected to dynamic loads, it is explained how they can be designed so that the structural eigenfrequencies of vibration are as far away as possible from a prescribed external excitation frequency (or a band of excitation frequencies) in order to avoid resonance phenomena with high vibration and noise levels. For diffusive and convective transport processes and multiphysics problems, applications of the density method are discussed. In order to take uncertainty in mater...

  10. Influence of the nutritional mechanism of fungi (mycorrhize/saprophyte) on the uptake of radionuclides by mycelium

    Energy Technology Data Exchange (ETDEWEB)

    Baeza, A.; Salas, A. [Dept. of Physics, Univ. of Extremadura, Caceres (Spain); Guillen, J. [Dept. of Physics, C.U.M., Univ. de Extremadura (Spain); Hernandez, S. [Dept. of Technics, Means, and Elements of Construction, Politechnics School, Univ. of Extremadura (Spain); Bernedo, M. [Dept. of Analytical Chemistry, Univ. of Alcala (Spain); Manjon, J.L.; Moreno, G. [Dept. of Vegetal Biology, Univ. of Alcala (Spain)

    2005-07-01

    Field studies have shown that the uptake of radionuclides by fungi depends on its nutritional mechanism (mycorrhizal or saprophytic), but this fact is only fully demonstrated for radiocaesium. To extend this conclusion to other radionuclides likely to be released in semi-natural ecosystems, we carried out a series of experiments under controlled laboratory conditions of the growth of mycelium of mycorrhizal and saprophytic fungi (Pleurotus eryngii and Hebeloma cylindrosporum respectively) on liquid culture media containing known added activities of {sup 60}Co, {sup 85}Sr, and {sup 134}Cs. The radionuclide incorporated most efficiently into Pleurotus eryngii was {sup 134}Cs, and into Hebeloma cylindrosporum was {sup 60}Co. For {sup 134}Cs and {sup 85}Sr, we also analysed the influence that the content of the chemically analogue elements K and Ca respectively in the culture medium had on its uptake. For both species, the uptake of {sup 134}Cs is not correlated with the content of K in the media, but it is the uptake of {sup 85}Sr increasing with it. These results seem to be independent of the nutritional mechanism. The influence of linearity in the uptake of {sup 134}Cs and {sup 85}Sr with increasing concentrations of Cs and Sr in the culture medium was also studied. For Pleurotus eryngii it was observed a decrease in the uptake of {sup 134}Cs with increasing Cs content in the medium, and an increase in the uptake of {sup 85}Sr with increasing Sr content in the medium. (orig.)

  11. Cellular uptake mechanism and intracellular fate of hydrophobically modified pullulan nanoparticles

    Directory of Open Access Journals (Sweden)

    Jiang L

    2013-05-01

    Full Text Available Liqin Jiang,1 Xuemin Li,1 Lingrong Liu,1 Qiqing Zhang1,21Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People's Republic of China; 2Research Center of Biomedical Engineering, Xiamen University, Xiamen, People's Republic of ChinaAbstract: The cellular uptake mechanism and intracellular fate of self-assembled nanoparticles (NPs of cholesterol-modified pullulan (CHSP by human hepatocellular carcinoma (HepG2 cells were investigated. Covalent conjugation with fluorescein isothiocyanate (FITC yielded stably labeled CHSP (FITC-CHSP, which was successfully formulated into NPs (mean particle size 63.0 ± 1.9 nm by dialysis. A cytotoxicity assay clearly indicated that the CHSP NPs did not show significant toxicity in HepG2 cells. The effects of NP concentration, incubation time, and temperature on the cellular uptake of the NPs were systematically evaluated by fluorometry, and the results suggested that cellular uptake of the NPs was concentration-, time-, and temperature-dependent. In vitro experiments with endocytic inhibitors revealed that clathrin-mediated endocytosis and macropinocytosis were involved in the internalization of CHSP NPs. The intracellular trafficking study demonstrated that CHSP NPs were entrapped in the lysosomes at 1 hour after incubation; colocalization of NPs with either the Golgi apparatus or the endoplasmic reticula was not observed during the entire course of the study. These results suggested that the CHSP NPs may serve as a versatile carrier for intracellular delivery of therapeutic agents.Keywords: cholesterol-modified pullulan, self-assembled nanoparticles, FITC, endocytosis, intracellular trafficking

  12. Cell-Penetrating Peptides—Mechanisms of Cellular Uptake and Generation of Delivery Systems

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    Sara Trabulo

    2010-03-01

    Full Text Available The successful clinical application of nucleic acid-based therapeutic strategies has been limited by the poor delivery efficiency achieved by existing vectors. The development of alternative delivery systems for improved biological activity is, therefore, mandatory. Since the seminal observations two decades ago that the Tat protein, and derived peptides, can translocate across biological membranes, cell-penetrating peptides (CPPs have been considered one of the most promising tools to improve non-invasive cellular delivery of therapeutic molecules. Despite extensive research on the use of CPPs for this purpose, the exact mechanisms underlying their cellular uptake and that of peptide conjugates remain controversial. Over the last years, our research group has been focused on the S413-PV cell-penetrating peptide, a prototype of this class of peptides that results from the combination of 13-amino-acid cell penetrating sequence derived from the Dermaseptin S4 peptide with the SV40 large T antigen nuclear localization signal. By performing an extensive biophysical and biochemical characterization of this peptide and its analogs, we have gained important insights into the mechanisms governing the interaction of CPPs with cells and their translocation across biological membranes. More recently, we have started to explore this peptide for the intracellular delivery of nucleic acids (plasmid DNA, siRNA and oligonucleotides. In this review we discuss the current knowledge of the mechanisms responsible for the cellular uptake of cell-penetrating peptides, including the S413-PV peptide, and the potential of peptide-based formulations to mediate nucleic acid delivery.

  13. Polycaprolactone/maltodextrin nanocarrier for intracellular drug delivery: formulation, uptake mechanism, internalization kinetics, and subcellular localization.

    Science.gov (United States)

    Korang-Yeboah, Maxwell; Gorantla, Yamini; Paulos, Simon A; Sharma, Pankaj; Chaudhary, Jaideep; Palaniappan, Ravi

    2015-01-01

    Prostate cancer (PCa) disease progression is associated with significant changes in intracellular and extracellular proteins, intracellular signaling mechanism, and cancer cell phenotype. These changes may have direct impact on the cellular interactions with nanocarriers; hence, there is the need for a much-detailed understanding, as nanocarrier cellular internalization and intracellular sorting mechanism correlate directly with bioavailability and clinical efficacy. In this study, we report the differences in the rate and mechanism of cellular internalization of a biocompatible polycaprolactone (PCL)/maltodextrin (MD) nanocarrier system for intracellular drug delivery in LNCaP, PC3, and DU145 PCa cell lines. PCL/MD nanocarriers were designed and characterized. PCL/MD nanocarriers significantly increased the intracellular concentration of coumarin-6 and fluorescein isothiocyanate-labeled bovine serum albumin, a model hydrophobic and large molecule, respectively. Fluorescence microscopy and flow cytometry analysis revealed rapid internalization of the nanocarrier. The extent of nanocarrier cellular internalization correlated directly with cell line aggressiveness. PCL/MD internalization was highest in PC3 followed by DU145 and LNCaP, respectively. Uptake in all PCa cell lines was metabolically dependent. Extraction of endogenous cholesterol by methyl-β-cyclodextrin reduced uptake by 75%±4.53% in PC3, 64%±6.01% in LNCaP, and 50%±4.50% in DU145, indicating the involvement of endogenous cholesterol in cellular internalization. Internalization of the nanocarrier in LNCaP was mediated mainly by macropinocytosis and clathrin-independent pathways, while internalization in PC3 and DU145 involved clathrin-mediated endocytosis, clathrin-independent pathways, and macropinocytosis. Fluorescence microscopy showed a very diffused and non-compartmentalized subcellular localization of the PCL/MD nanocarriers with possible intranuclear localization and minor colocalization in

  14. Mechanism of cellular uptake and impact of ferucarbotran on macrophage physiology.

    Directory of Open Access Journals (Sweden)

    Chung-Yi Yang

    Full Text Available Superparamagnetic iron oxide (SPIO nanoparticles are contrast agents used for magnetic resonance imaging. Ferucarbotran is a clinically approved SPIO-coated carboxydextran with a diameter of about 45-60 nm. We investigated the mechanism of cellular uptake of Ferucarbotran with a cell model using the murine macrophage cell line Raw 264.7. We observed a dose-dependent uptake of these SPIO particles by spectrophotometer analysis and also a dose-dependent increase in the granularity of the macrophages as determined by flow cytometry. There was a linear correlation between the side scattering mean value and iron content (P<0.001, R(2 = 0. 8048. For evaluation of the endocytotic pathway of these ingested SPIO particles, different inhibitors of the endocytotic pathways were employed. There was a significant decrease of side scattering counts in the cells and a less significant change in signal intensity based on magnetic resonance in the phenylarsine oxide-treated macrophages. After labeling with SPIO particles, the macrophages showed an increase in the production of reactive oxygen species at 2, 24, and 48 h; a decrease in mitochondrial membrane potential at 24 h; and an increase in cell proliferation at 24 h. We concluded that Ferucarbotran was internalized into macrophages via the clathrin-mediated pathway and can change the cellular behavior of these cells after labeling.

  15. Mechanisms controlling arsenic uptake in rice grown in mining impacted regions in South China.

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    Junhui Li

    Full Text Available Foods produced on soils impacted by Pb-Zn mining activities are a potential health risk due to plant uptake of the arsenic (As associated with such mining. A field survey was undertaken in two Pb-Zn mining-impacted paddy fields in Guangdong Province, China to assess As accumulation and translocation, as well as other factors influencing As in twelve commonly grown rice cultivars. The results showed that grain As concentrations in all the surveyed rice failed national food standards, irrespective of As speciation. Among the 12 rice cultivars, "SY-89" and "DY-162" had the least As in rice grain. No significant difference for As concentration in grain was observed between the rice grown in the two areas that differed significantly for soil As levels, suggesting that the amount of As contamination in the soil is not necessarily the overriding factor controlling the As content in the rice grain. The iron and manganese plaque on the root surface curtailed As accumulation in rice roots. Based on our results, the accumulation of As within rice plants was strongly associated with such soil properties such as silicon, phosphorus, organic matter, pH, and clay content. Understanding the factors and mechanisms controlling As uptake is important to develop mitigation measures that can reduce the amount of As accumulated in rice grains produced on contaminated soils.

  16. Blood-brain barrier permeability and brain uptake mechanism of kainic acid and dihydrokainic acid.

    Science.gov (United States)

    Gynther, Mikko; Petsalo, Aleksanteri; Hansen, Steen H; Bunch, Lennart; Pickering, Darryl S

    2015-03-01

    The glutamatergic neurotransmitter system is involved in important neurophysiological processes and thus constitutes a promising target for the treatment of neurological diseases. The two ionotropic glutamate receptor agonists kainic acid (KA) and dihydrokainic acid (DHK) have been used as research tools in various in vivo central nervous system disease models in rodents, as well as being templates in the design of novel ligands affecting the glutamatergic system. Both molecules are highly polar but yet capable of crossing the blood-brain barrier (BBB). We used an in situ rat brain perfusion technique to determine the brain uptake mechanism and permeability across the BBB. To determine KA and DHK concentrations in the rat brain, simple and rapid sample preparation and liquid chromatography mass spectrometer methods were developed. According to our results the BBB permeability of KA and DHK is low, 0.25 × 10(-6) and 0.28 × 10(-6) cm/s for KA and DHK, respectively. In addition, the brain uptake is mediated by passive diffusion, and not by active transport. Furthermore, the non-specific plasma and brain protein binding of KA and DHK was determined to be low, which means that the unbound drug volume of distribution in brain is also low. Therefore, even though the total KA and DHK concentrations in the brain are low after systemic dosing, the concentrations in the vicinity of the glutamate receptors are sufficient for their activation and thus the observed efficacy.

  17. Understanding mechanisms to predict and optimize biochar for agrochemical sorption

    Science.gov (United States)

    Hall, Kathleen; Gámiz, Beatriz; Cox, Lucia; Spokas, Kurt; Koskinen, William

    2017-04-01

    The ability of biochars to bind various organic compounds has been widely studied due to the potential effects on pesticide fate in soil and interest in the adoption of biochar as a "low-cost" filter material. However, the sorptive behaviors of biochars are extremely variable and much of the reported data is limited to specific biochar-chemical interactions. The lack of knowledge regarding biochar sorption mechanisms limits our current ability to predict and optimize biochar's use. This work unveils mechanistic drivers of organic pesticide sorption on biochars through targeted alteration of biochar surface chemistry. Changes in the quantity and type of functional groups on biochars and other black carbon materials were achieved through treatments with H2O2, and CO2, and characterized using Fourier transform infrared spectroscopy and scanning electron microscope (SEM/EDX). The sorption capacities of these treated biochars were subsequently measured to evaluate the effects of different surface moieties on the binding of target herbicides cyhalofop acid ((R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propionic acid) and clomazone (2-[(2-chlorophenyl)methyl]-4,4-dimethyl-1,2-oxazolidin-3-one). Sorption of both herbicides on the studied biochars increased following H2O2 activation; however, the influence of the H2O2 activation on sorption was more pronounced for cyhalofop acid (pKa = 3.9) than clomazone, which is non-ionizable. Increased cyhalofop acid sorption on H2O2 treated biochars can be attributed to the increase in oxygen containing functional groups as well as the decrease in biochar pH. In contrast, CO2 activation reduced the sorption of cyhalofop acid compared to untreated biochar. FTIR data suggest the reduced sorption on CO2 -treated biochar was due to the removal of surface carboxyl groups, further supporting the role of specific functionality in the sorption of ionizable herbicides. Results from this work offer insight into the mechanisms of sorption and

  18. Structural insights into the mechanisms of Mg2+ uptake, transport, and gating by CorA.

    Science.gov (United States)

    Guskov, Albert; Nordin, Nurhuda; Reynaud, Aline; Engman, Henrik; Lundbäck, Anna-Karin; Jong, Agnes Jin Oi; Cornvik, Tobias; Phua, Terri; Eshaghi, Said

    2012-11-06

    Despite the importance of Mg(2+) for numerous cellular activities, the mechanisms underlying its import and homeostasis are poorly understood. The CorA family is ubiquitous and is primarily responsible for Mg(2+) transport. However, the key questions-such as, the ion selectivity, the transport pathway, and the gating mechanism-have remained unanswered for this protein family. We present a 3.2 Å resolution structure of the archaeal CorA from Methanocaldococcus jannaschii, which is a unique complete structure of a CorA protein and reveals the organization of the selectivity filter, which is composed of the signature motif of this family. The structure reveals that polar residues facing the channel coordinate a partially hydrated Mg(2+) during the transport. Based on these findings, we propose a unique gating mechanism involving a helical turn upon the binding of Mg(2+) to the regulatory intracellular binding sites, and thus converting a polar ion passage into a narrow hydrophobic pore. Because the amino acids involved in the uptake, transport, and gating are all conserved within the entire CorA family, we believe this mechanism is general for the whole family including the eukaryotic homologs.

  19. Multiscale Mechanics and Optimization of Gastropod Shells

    Institute of Scientific and Technical Information of China (English)

    Mostafa Yourdkhani; Damiano Pasini; Francois Barthelat

    2011-01-01

    A vast majority of mollusks grow a hard shell for protection.The structure of these shells comprises several levels of hierarchy that increase their strength and their resistance to natural threats.This article focuses on nacreous shells,which are composed of two distinct layers.The outer layer is made of calcite,which is a hard but brittle material,and the inner layer is made of nacre,a tough and ductile material.The inner and outer layers are therefore made of materials with distinct structures and properties.In this article,we demonstrate that this system is optimum to defeat attacks from predators.A two-scale modeling and optimization approach was used.At the macroscale,a two-layer finite element model of a seashell was developed to capture shell geometry.At the microscale,a representative volume element of the microstructure of nacre was used to model the elastic modulus of nacre as well as a multiaxial failure criterion,both expressed as function of microstructural parameters.Experiments were also performed on actual shells of red abalone to validate the results obtained from simulations and gain insight into the way the shell fails under sharp perforation.Both optimization and experimental results revealed that the shell displays optimum performance when two modes of failure coincide within the structure.Finally,guidelines for designing two-layer shells were proposed to improve the performance of engineered protective systems undergoing similar structural and loading conditions.

  20. Subcellular distribution and uptake mechanism of di-n-butyl phthalate in roots of pumpkin (Cucurbita moschata) seedlings.

    Science.gov (United States)

    Lin, Qingqi; Yang, Xiuhong; Huang, Xiongfei; Wang, Shizhong; Chao, Yuanqing; Qiu, Rongliang

    2016-01-01

    Phthalate acid esters (PAEs) are of particular concern due to their potential environmental risk to human and nonhuman organisms. Although uptake of PAEs by plants has been reported by several researchers, information about the intracellular distribution and uptake mechanisms of PAEs is still lacking. In this study, a series of hydroponic experiments using intact pumpkin (Cucurbita moschata) seedlings was conducted to investigate how di-n-butyl phthalate (DnBP), one of the most frequently identified PAEs in the environment, enters and is distributed in roots. DnBP was transported into subcellular tissues rapidly in the initial uptake period (<12 h). More than 80% of DnBP was detected in the cell walls and organelles, which suggests that DnBP is primarily accumulated in these two fractions due to their high affinity to DnBP. The kinetics of DnBP uptake were fitted well with the Michaelis-Menten equation, suggesting that a carrier-mediated process was involved. The application of 2,4-dinitrophenol and sodium vanadate reduced the uptake of DnBP by 37 and 26%, respectively, while aquaporin inhibitors, silver and glycerol, had no effect on DnBP uptake. These data demonstrated that the uptake of DnBP included a carrier-mediated and energy-dependent process without the participation of aquaporins.

  1. Elucidating the mechanisms of nickel compound uptake: A review of particulate and nano-nickel endocytosis and toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz, Alexandra; Costa, Max, E-mail: Max.Costa@nyumc.org

    2012-04-01

    Nickel (Ni) is a worldwide pollutant and contaminant that humans are exposed to through various avenues resulting in multiple toxic responses — most alarming is its clear carcinogenic nature. A variety of particulate Ni compounds persist in the environment and can be distinguished by characteristics such as solubility, structure, and surface charge. These characteristics influence cellular uptake and toxicity. Some particulate forms of Ni are carcinogenic and are directly and rapidly endocytized by cells. A series of studies conducted in the 1980s observed this process, and we have reanalyzed the results of these studies to help elucidate the molecular mechanism of particulate Ni uptake. Originally the process of uptake observed was described as phagocytosis, however in the context of recent research we hypothesize that the process is macropinocytosis and/or clathrin mediated endocytosis. Primary considerations in determining the route of uptake here include calcium dependence, particle size, and inhibition through temperature and pharmacological approaches. Particle characteristics that influenced uptake include size, charge, surface characteristics, and structure. This discussion is relevant in the context of nanoparticle studies and the emerging interest in nano-nickel (nano-Ni), where toxicity assessments require a clear understanding of the parameters of particulate uptake and where establishment of such parameters is often obscured through inconsistencies across experimental systems. In this regard, this review aims to carefully document one system (particulate nickel compound uptake) and characterize its properties.

  2. Universally Optimal Privacy Mechanisms for Minimax Agents

    CERN Document Server

    Gupte, Mangesh

    2010-01-01

    A scheme that publishes aggregate information about sensitive data must resolve the trade-off between utility to information consumers and privacy of the database participants. Differential privacy is a well-established definition of privacy--this is a universal guarantee against all attackers, whatever their side-information or intent. In this paper, we present a universal treatment of utility based on the standard minimax rule from decision theory (in contrast to the utility model in, which is Bayesian). In our model, information consumers are minimax (risk-averse) agents, each possessing some side-information about the query, and each endowed with a loss-function which models their tolerance to inaccuracies. Further, information consumers are rational in the sense that they actively combine information from the mechanism with their side-information in a way that minimizes their loss. Under this assumption of rational behavior, we show that for every fixed count query, a certain geometric mechanism is unive...

  3. Mechanisms of dsRNA uptake in insects and potential of RNAi for pest control: a review.

    Science.gov (United States)

    Huvenne, Hanneke; Smagghe, Guy

    2010-03-01

    RNA interference already proved its usefulness in functional genomic research on insects, but it also has considerable potential for the control of pest insects. For this purpose, the insect should be able to autonomously take up the dsRNA, for example through feeding and digestion in its midgut. In this review we bring together current knowledge on the uptake mechanisms of dsRNA in insects and the potential of RNAi to affect pest insects. At least two pathways for dsRNA uptake in insects are described: the transmembrane channel-mediated uptake mechanism based on Caenorhabditis elegans' SID-1 protein and an 'alternative' endocytosis-mediated uptake mechanism. In the second part of the review dsRNA feeding experiments on insects are brought together for the first time, highlighting the achievement of implementing RNAi in insect control with the first successful experiments in transgenic plants and the diversity of successfully tested insect orders/species and target genes. We conclude with points of discussion and concerns regarding further research on dsRNA uptake mechanisms and the promising application possibilities for RNAi in insect control.

  4. Uptake mechanism of ApoE-modified nanoparticles on brain capillary endothelial cells as a blood-brain barrier model.

    Directory of Open Access Journals (Sweden)

    Sylvia Wagner

    Full Text Available BACKGROUND: The blood-brain barrier (BBB represents an insurmountable obstacle for most drugs thus obstructing an effective treatment of many brain diseases. One solution for overcoming this barrier is a transport by binding of these drugs to surface-modified nanoparticles. Especially apolipoprotein E (ApoE appears to play a major role in the nanoparticle-mediated drug transport across the BBB. However, at present the underlying mechanism is incompletely understood. METHODOLOGY/PRINCIPAL FINDINGS: In this study, the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells was investigated to differentiate between active and passive uptake mechanism by flow cytometry and confocal laser scanning microscopy. Furthermore, different in vitro co-incubation experiments were performed with competing ligands of the respective receptor. CONCLUSIONS/SIGNIFICANCE: This study confirms an active endocytotic uptake mechanism and shows the involvement of low density lipoprotein receptor family members, notably the low density lipoprotein receptor related protein, on the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells. This knowledge of the uptake mechanism of ApoE-modified nanoparticles enables future developments to rationally create very specific and effective carriers to overcome the blood-brain barrier.

  5. Investigation of biomimetic shear stress on cellular uptake and mechanism of polystyrene nanoparticles in various cancer cell lines.

    Science.gov (United States)

    Kang, Taehee; Park, Chulhun; Lee, Beom-Jin

    2016-12-01

    Cancer cells in the tumor microenvironment are affected by fluid shear stress generated by blood flow in the vascular microenvironment and interstitial flows in the tumor microenvironment. Thus, we investigated how fluidic shear stress affects cellular uptake as well as the endocytosis mechanism of nanoparticles using a biomimetic microfluidic system that mimics the human dynamic environment. Positively charged amino-modified polystyrene nanoparticles (PSNs) at 100 μg/mL were delivered to cancer cells under static and biomimetic dynamic conditions (0.5 dyne/cm(2)). Additionally, the experiment was done in the presence of endocytosis inhibitors specific for one of the endocytosis pathways. To evaluate cellular uptake of cationic PSNs, the fluorescence intensity of cationic PSNs in cancer cells was measured by flow cytometer and fluorescence images were taken using confocal laser scanning microscopy. Cancer cells in dynamic conditions exhibited higher cellular uptake of PSNs and showed different cellular uptake mechanisms compared with those in static conditions. From these results, it suggested that biomimetic dynamic conditions stimulated specific endocytosis and prompted cellular uptake. It was also important to consider fluidic shear stress as one of the critical factors because cellular uptake and drug delivery could play a key role in cancer cells and metastasis.

  6. A systematic in vitro investigation on poly-arginine modified nanostructured lipid carrier: Pharmaceutical characteristics, cellular uptake, mechanisms and cytotoxicity

    Directory of Open Access Journals (Sweden)

    Mingshuang Sun

    2017-01-01

    Full Text Available The aim of the present study was to develop a poly-arginine modified nanostructured lipid carrier (R-NLC by fusion-emulsification method and to test its pharmaceutical characteristics. The influence of R-NLC on A549 cells like cellular uptake and cytotoxicity was also appraised using unmodified NLC as the controlled group. As the results revealed, R-NLC had an average diameter of about 40 nm and a positive zeta potential of about +17 mv, the entrapment efficiency decreased apparently, and no significant difference on the in vitro drug release was found after R8-modification. The cellular uptake and cytotoxicity increased obviously compared with unmodified NLC. The cellular uptake mechanisms of R-NLC involved energy, macropinocytosis, clathrin-mediated endocytosis, and caveolin-mediated endocytosis. The outcomes of the present study strongly support the theory that cell penetrating peptides have the ability of enhancing the cellular uptake of nanocarriers.

  7. The Optimization Design of Six-bar Linkage Mechanism

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2013-07-01

    Full Text Available At present, multi-bar linkage mechanism is one of the most important directions of mechanical presses’ development. Utilizing the typical multi-linkage drawing mechanism of the plunger slide and compounding its parameters scientifically are a fairly effective way to realize the drawing technology demand. This paper established kinematics mode of the six-bar drawing mechanism by bar-group method, and produced simulated system by Visual Basic, which simulated the actual motion of the mechanism. With the objective function-velocity fluctuation in drawing and drawing depth, using chaos genetic algorithm method, carried out optimization design of the mechanism, and acquired several groups’ data. The optimization results showed that their performance in kinematics was improved greatly and had exceeded the original mechanism.  

  8. Mechanism of neuronal versus endothelial cell uptake of Alzheimer's disease amyloid beta protein.

    Directory of Open Access Journals (Sweden)

    Karunya K Kandimalla

    Full Text Available Alzheimer's disease (AD is characterized by significant neurodegeneration in the cortex and hippocampus; intraneuronal tangles of hyperphosphorylated tau protein; and accumulation of beta-amyloid (Abeta proteins 40 and 42 in the brain parenchyma as well as in the cerebral vasculature. The current understanding that AD is initiated by the neuronal accumulation of Abeta proteins due to their inefficient clearance at the blood-brain-barrier (BBB, places the neurovascular unit at the epicenter of AD pathophysiology. The objective of this study is to investigate cellular mechanisms mediating the internalization of Abeta proteins in the principle constituents of the neurovascular unit, neurons and BBB endothelial cells. Laser confocal micrographs of wild type (WT mouse brain slices treated with fluorescein labeled Abeta40 (F-Abeta40 demonstrated selective accumulation of the protein in a subpopulation of cortical and hippocampal neurons via nonsaturable, energy independent, and nonendocytotic pathways. This groundbreaking finding, which challenges the conventional belief that Abeta proteins are internalized by neurons via receptor mediated endocytosis, was verified in differentiated PC12 cells and rat primary hippocampal (RPH neurons through laser confocal microscopy and flow cytometry studies. Microscopy studies have demonstrated that a significant proportion of F-Abeta40 or F-Abeta42 internalized by differentiated PC12 cells or RPH neurons is located outside of the endosomal or lysosomal compartments, which may accumulate without degradation. In contrast, BBME cells exhibit energy dependent uptake of F-Abeta40, and accumulate the protein in acidic cell organelle, indicative of endocytotic uptake. Such a phenomenal difference in the internalization of Abeta40 between neurons and BBB endothelial cells may provide essential clues to understanding how various cells can differentially regulate Abeta proteins and help explain the vulnerability of cortical

  9. Cell uptake mechanisms of PAMAM G4-FITC dendrimer in human myometrial cells

    Energy Technology Data Exchange (ETDEWEB)

    Oddone, Natalia; Zambrana, Ana I.; Tassano, Marcos [Instituto de Investigaciones Biologicas Clemente Estable, Laboratorio de Senalizacion Celular y Nanobiologia (Uruguay); Porcal, Williams [Universidad de la Republica, Grupo de Quimica Medicinal, Instituto de Quimica Biologica, Facultad de Ciencias-Facultad de Quimica (Uruguay); Cabral, Pablo [Universidad de la Republica, Laboratorio de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias (Uruguay); Benech, Juan C., E-mail: benech@iibce.edu.uy [Instituto de Investigaciones Biologicas Clemente Estable, Laboratorio de Senalizacion Celular y Nanobiologia (Uruguay)

    2013-07-15

    The high incidence and severity of diseases which involve smooth muscle dysfunction dictates the need of continued search for novel therapeutic strategies to treat these conditions. Dendrimers are branched macromolecules with multiple end-groups that can be functionalized for applications which include drug delivery. There is no data regarding the cellular uptake mechanisms used by dendrimers in smooth muscle human myometrial cells (HMC). Polyamidoamine G4 dendrimers were conjugated with fluorescein isothiocyanate (FITC) and the resulting conjugate (G4-FITC) was characterized using high-performance liquid chromatography, nuclear magnetic resonance, and atomic force microscopy. G4-FITC showed to have no significant effect on the primary culture HMC viability up to 48 h. HMC incubated with G4-FITC were analyzed by laser confocal microscopy. Peri-nuclear fluorescence distribution was observed at 5 h of incubation or more (24, 36, and 48 h). At 24 h, G4-FITC partially co-localized with lysotracker. Uptake of G4-FITC by HMC was slightly inhibited by filipin (8.0 {+-} 3.9 %) and significantly inhibited by chlorpromazine (63.5 {+-} 3.7 %). In non-electroporated HMC, G4-FITC was never observed inside the cell nucleus. Interestingly, we detected G4-FITC inside the nuclear domain of some electroporated cells. Thus, electroporation changed intracellular G4-FITC localization. Isolated nuclei of HMC incubated with G4-FITC showed fluorescence signal inside the nuclear domain. The results suggest that in HMC, G4-FITC is taken up by clathrin-mediated endocytosis with endosomal and lysosomal localization at 24 h. The combination of electroporation and dendrimers could be an interesting technology to electrotransfer drugs into smooth muscle cells cytosol and nuclei.

  10. Cell uptake mechanisms of PAMAM G4-FITC dendrimer in human myometrial cells

    Science.gov (United States)

    Oddone, Natalia; Zambrana, Ana I.; Tassano, Marcos; Porcal, Williams; Cabral, Pablo; Benech, Juan C.

    2013-07-01

    The high incidence and severity of diseases which involve smooth muscle dysfunction dictates the need of continued search for novel therapeutic strategies to treat these conditions. Dendrimers are branched macromolecules with multiple end-groups that can be functionalized for applications which include drug delivery. There is no data regarding the cellular uptake mechanisms used by dendrimers in smooth muscle human myometrial cells (HMC). Polyamidoamine G4 dendrimers were conjugated with fluorescein isothiocyanate (FITC) and the resulting conjugate (G4-FITC) was characterized using high-performance liquid chromatography, nuclear magnetic resonance, and atomic force microscopy. G4-FITC showed to have no significant effect on the primary culture HMC viability up to 48 h. HMC incubated with G4-FITC were analyzed by laser confocal microscopy. Peri-nuclear fluorescence distribution was observed at 5 h of incubation or more (24, 36, and 48 h). At 24 h, G4-FITC partially co-localized with lysotracker. Uptake of G4-FITC by HMC was slightly inhibited by filipin (8.0 ± 3.9 %) and significantly inhibited by chlorpromazine (63.5 ± 3.7 %). In non-electroporated HMC, G4-FITC was never observed inside the cell nucleus. Interestingly, we detected G4-FITC inside the nuclear domain of some electroporated cells. Thus, electroporation changed intracellular G4-FITC localization. Isolated nuclei of HMC incubated with G4-FITC showed fluorescence signal inside the nuclear domain. The results suggest that in HMC, G4-FITC is taken up by clathrin-mediated endocytosis with endosomal and lysosomal localization at 24 h. The combination of electroporation and dendrimers could be an interesting technology to electrotransfer drugs into smooth muscle cells cytosol and nuclei.

  11. MECHANISMS AND OPTIMIZATION OF COAL COMBUSTION

    Energy Technology Data Exchange (ETDEWEB)

    Kyriacos Zygourakis

    2000-10-31

    The completed research project has made some significant contributions that will help us meet the challenges outlined in the previous section. One of the major novelties of our experimental approach involves the application of video microscopy and digital image analysis to study important transient phenomena (like particle swelling and ignitions) occurring during coal pyrolysis and combustion. Image analysis was also used to analyze the macropore structure of chars, a dominant factor in determining char reactivity and ignition behavior at high temperatures where all the commercial processes operate. By combining advanced experimental techniques with mathematical modeling, we were able to achieve the main objectives of our project. More specifically: (1) We accurately quantified the effect of several important process conditions (like pyrolysis heating rate, particle size, heat treatment temperature and soak time) on the combustion behavior of chars. These measurements shed new light into the fundamental mechanisms of important transient processes like particle swelling and ignitions. (2) We developed and tested theoretical models that can predict the ignition behavior of char particles and their burn-off times at high temperatures where intraparticle diffusional limitations are very important.

  12. Investigating the Uptake Mechanisms of Hydrogen Peroxide to Single and Polycrystalline Ice with a Novel Flow Tube System

    Science.gov (United States)

    Hong, Angela; Ammann, Markus; Bartels-Rausch, Thorsten

    2016-04-01

    Air-ice chemical interactions are important for describing the distribution and subsequent chemical fate of trace atmospheric gases within ice and snow and determining the oxidative capacities of these environments. The nature of this interaction is governed by a compound's physicochemical properties as well as ice microstructure. Hydrogen peroxide (H2O2), a reservoir of HOx radicals in the atmosphere and an important chromophore in snow and ice, is a trace gas that demonstrates complex uptake behaviour to frozen aqueous media by the reversible, fast adsorption to the air-ice interface, aggregation, and lateral interactions, and a slower process, ostensibly via uptake into the bulk. However, the exact mechanism and kinetics for the slow uptake of H2O2 and the size of this reservoir is unknown. It is important to describe and quantify this loss term, over environmentally-relevant timescales, accommodation of H2O2 into the bulk may be the dominant process which controls the composition and chemistry of the snow and overlying atmosphere. We hypothesize that the slow uptake of H2O2 occurs by diffusion into the grain boundaries of ice. To provide mechanistic insight to the macroscopic phenomenon of atmospheric gas uptake to ice, and discern various mechanisms including adsorption to air-ice interface and accommodation into the bulk through uptake into grain boundaries, we design, machine, and validate a novel flow reactor system featuring a Drilled Ice Flow Tube (DIFT). Our flow reactor system is uniquely suited to testing these uptake mechanisms: by controlling the degree of grain boundaries present in the DIFT (ie. monocrystalline or polycrystalline), we can directly observe the effect of the ice microstructure on the adsorptive and bulk uptake of trace atmospheric gases over long timescales (eg. on the order of hours). Here, we describe method development of the DIFT and demonstrate using polarised microscopy imagery that our experimental set-up allows for the direct

  13. Optimal charging profiles for mechanically constrained lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Suthar, B; Ramadesigan, V; De, S; Braatz, RD; Subramanian, VR

    2014-01-01

    The cost and safety related issues of lithium-ion batteries require intelligent charging profiles that can efficiently utilize the battery. This paper illustrates the application of dynamic optimization in obtaining the optimal current profile for charging a lithium-ion battery using a single-particle model while incorporating intercalation-induced stress generation. In this paper, we focus on the problem of maximizing the charge stored in a given time while restricting the development of stresses inside the particle. Conventional charging profiles for lithium-ion batteries (e.g., constant current followed by constant voltage) were not derived by considering capacity fade mechanisms. These charging profiles are not only inefficient in terms of lifetime usage of the batteries but are also slower since they do not exploit the changing dynamics of the system. Dynamic optimization based approaches have been used to derive optimal charging and discharging profiles with different objective functions. The progress made in understanding the capacity fade mechanisms has paved the way for inclusion of that knowledge in deriving optimal controls. While past efforts included thermal constraints, this paper for the first time presents strategies for optimally charging batteries by guaranteeing minimal mechanical damage to the electrode particles during intercalation. In addition, an executable form of the code has been developed and provided. This code can be used to identify optimal charging profiles for any material and design parameters.

  14. Redox-Dependent Conformational Changes in Cytochrome c Oxidase Suggest a Gating Mechanism for Proton Uptake

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Ling; Liu, Jian; Mills, Denise A.; Proshlyakov, Denis A.; Hiser, Carrie; Ferguson-Miller, Shelagh; (MSU)

    2009-08-05

    A role for conformational change in the coupling mechanism of cytochrome c oxidase is the subject of controversy. Relatively small conformational changes have been reported in comparisons of reduced and oxidized crystal structures of bovine oxidase but none in bacterial oxidases. Comparing the X-ray crystal structures of the reduced (at 2.15 {angstrom} resolution) and oxidized forms of cytochrome c oxidase from Rhodobacter sphaeroides, we observe a displacement of heme a3 involving both the porphyrin ring and the hydroxyl farnesyl tail, accompanied by protein movements in nearby regions, including the mid part of helix VIII of subunit I which harbors key residues of the K proton uptake path, K362 and T359. The conformational changes in the reduced form are reversible upon reoxidation. They result in an opening of the top of the K pathway and more ordered waters being resolved in that region, suggesting an access path for protons into the active site. In all high-resolution structures of oxidized R. sphaeroides cytochrome c oxidase, a water molecule is observed in the hydrophobic region above the top of the D path, strategically positioned to facilitate the connection of residue E286 of subunit I to the active site or to the proton pumping exit path. In the reduced and reduced plus cyanide structures, this water molecule disappears, implying disruption of proton conduction from the D path under conditions when the K path is open, thus providing a mechanism for alternating access to the active site.

  15. Gallium scintigraphy demonstration of an appendiceal mucocele: a proposed mechanism of uptake

    Energy Technology Data Exchange (ETDEWEB)

    Alpert, L.; Friedman, R.

    1981-08-01

    An appendiceal mucocele demonstrated intense early avidity for Ga-67, despite the lack of inflammatory cells to account for the uptake. It is proposed that the acid mucopolysaccharide component of the mucus within the lumen and lining cells accounted for the uptake of the gallium ion, in a similar manner to the uptake of its analogue, the ferric ion, as demonstrated by intense staining of mucus by the colloidal iron technique.

  16. Optimization of chelators to enhance uranium uptake from tailings for phytoremediation.

    Science.gov (United States)

    Jagetiya, Bhagawatilal; Sharma, Anubha

    2013-04-01

    A greenhouse experiment was set up to investigate the ability of citric acid (CA), oxalic acid (OA), nitrilotriacetic acid (NTA) and EDTA for phytoremediation of uranium tailings by Indian mustard [Brassica juncea (L.) Czern. et Coss]. Uranium tailings were collected from Umra mining region and mixed with 75% of garden soil which yielded a 25:75 mixture. Prepared pots were divided into four sets and treated with following different concentrations - 0.1, 0.5, 2.5 and 12.5 mmol kg(-1) soil additions for each of the four chelators. Control pots which were not treated with chelators. Experiments were conducted in completely randomized block design with triplicates. The optimum concentrations of these chelators were found on the basis of biomass production, tolerance and accumulation potential. The data collected were expressed statistically. EDTA produced maximum growth depression whereas, minimum occurred in the case of NTA. Maximum U uptake (3.5-fold) in the roots occurred at 2.5 mmol of CA, while NTA proved to be the weakest for the same purpose. Severe toxicity in the form of reduced growth and plant death was recorded at 12.5 mmol of each chelator. Minimum growth inhibition produced by chelators occurred in NTA which was followed by OA, moderate in CA and maximum was traced in EDTA applications. Chelator strengthened U uptake in the present study follows the order: CA>EDTA>OA>NTA.

  17. Intrinsic Optimal Control for Mechanical Systems on Lie Group

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2017-01-01

    Full Text Available The intrinsic infinite horizon optimal control problem of mechanical systems on Lie group is investigated. The geometric optimal control problem is built on the intrinsic coordinate-free model, which is provided with Levi-Civita connection. In order to obtain an analytical solution of the optimal problem in the geometric viewpoint, a simplified nominal system on Lie group with an extra feedback loop is presented. With geodesic distance and Riemann metric on Lie group integrated into the cost function, a dynamic programming approach is employed and an analytical solution of the optimal problem on Lie group is obtained via the Hamilton-Jacobi-Bellman equation. For a special case on SO(3, the intrinsic optimal control method is used for a quadrotor rotation control problem and simulation results are provided to show the control performance.

  18. A Pareto Optimal Auction Mechanism for Carbon Emission Rights

    Directory of Open Access Journals (Sweden)

    Mingxi Wang

    2014-01-01

    Full Text Available The carbon emission rights do not fit well into the framework of existing multi-item auction mechanisms because of their own unique features. This paper proposes a new auction mechanism which converges to a unique Pareto optimal equilibrium in a finite number of periods. In the proposed auction mechanism, the assignment outcome is Pareto efficient and the carbon emission rights’ resources are efficiently used. For commercial application and theoretical completeness, both discrete and continuous markets—represented by discrete and continuous bid prices, respectively—are examined, and the results show the existence of a Pareto optimal equilibrium under the constraint of individual rationality. With no ties, the Pareto optimal equilibrium can be further proven to be unique.

  19. The Process of Optimizing Mechanical Sound Quality in Product Design

    DEFF Research Database (Denmark)

    Eriksen, Kaare; Holst, Thomas

    2011-01-01

    clarify the importance of product sound, defining perceptive demands identified by users, and, finally, how to suggest mechanical principles for modification of an existing sound design. The optimized mechanical sound design is followed by tests on users of the product in its use context. The result......The research field concerning optimizing product sound quality is a relatively unexplored area, and may become difficult for designers to operate in. To some degree, sound is a highly subjective parameter, which is normally targeted sound specialists. This paper describes the theoretical...... and practical background for managing a process of optimizing the mechanical sound quality in a product design by using simple tools and workshops systematically. The procedure is illustrated by a case study of a computer navigation tool (computer mouse or mouse). The process is divided into 4 phases, which...

  20. Stress-constrained topology optimization for compliant mechanism design

    DEFF Research Database (Denmark)

    de Leon, Daniel M.; Alexandersen, Joe; Jun, Jun S.;

    2015-01-01

    This article presents an application of stress-constrained topology optimization to compliant mechanism design. An output displacement maximization formulation is used, together with the SIMP approach and a projection method to ensure convergence to nearly discrete designs. The maximum stress...... is approximated using a normalized version of the commonly-used p-norm of the effective von Mises stresses. The usual problems associated with topology optimization for compliant mechanism design: one-node and/or intermediate density hinges are alleviated by the stress constraint. However, it is also shown...

  1. Macro- and microspectroscopic study of Nd (III) uptake mechanisms in hardened cement paste.

    Science.gov (United States)

    Mandaliev, Peter; Dähn, Rainer; Wehrli, Bernhard; Wieland, Erich

    2009-11-01

    Cement is an important component in repositories for low-level and intermediate-level radioactive waste. Nd uptake by hardened cement paste (HCP) has been investigated with the aim of developing a mechanistic understanding of the immobilization processes of trivalent lanthanides and actinides in HCP on the molecular level. Information on the microstructure of HCP, the Nd distribution in the cement matrix, and the coordination environment of Nd in these matrices was gained from the combined use of scanning electron microscopy (SEM), synchrotron-based micro-X-ray fluorescence (micro-XRF), micro-X-ray (micro-XAS), and bulk-X-ray absorption spectroscopy (bulk-XAS) on Nd doped cement samples. The samples were reacted over periods of time between 15 min and 200 days. SEM and micro-XRF investigations suggest preferential Nd accumulation in rims around "inner"-calcium silicate hydrates (C-S-H). The EXAFS data indicate that the coordination environment of Nd taken up by HCP was dependent on reaction time. Changes in the structural parameters derived from EXAFS support the idea of Nd incorporation into the structure of C-S-H phases. The Nd binding mechanisms proposed in this study have implication for an overall assessment of the safe disposal of trivalent actinides in cement-based repositories for radioactive waste.

  2. Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Antonio Perfecto

    2017-04-01

    Full Text Available Food fortification programs to reduce iron deficiency anemia require bioavailable forms of iron that do not cause adverse organoleptic effects. Rodent studies show that nano-sized ferric phosphate (NP-FePO4 is as bioavailable as ferrous sulfate, but there is controversy over the mechanism of absorption. We undertook in vitro studies to examine this using a Caco-2 cell model and simulated gastrointestinal (GI digestion. Supernatant iron concentrations increased inversely with pH, and iron uptake into Caco-2 cells was 2–3 fold higher when NP-FePO4 was digested at pH 1 compared to pH 2. The size and distribution of NP-FePO4 particles during GI digestion was examined using transmission electron microscopy. The d50 of the particle distribution was 413 nm. Using disc centrifugal sedimentation, a high degree of agglomeration in NP-FePO4 following simulated GI digestion was observed, with only 20% of the particles ≤1000 nm. In Caco-2 cells, divalent metal transporter-1 (DMT1 and endocytosis inhibitors demonstrated that NP-FePO4 was mainly absorbed via DMT1. Small particles may be absorbed by clathrin-mediated endocytosis and micropinocytosis. These findings should be considered when assessing the potential of iron nanoparticles for food fortification.

  3. Effects of optimized root water uptake parameterization schemes on water and heat flux simulation in a maize agroecosystem

    Science.gov (United States)

    Cai, Fu; Ming, Huiqing; Mi, Na; Xie, Yanbing; Zhang, Yushu; Li, Rongping

    2017-04-01

    As root water uptake (RWU) is an important link in the water and heat exchange between plants and ambient air, improving its parameterization is key to enhancing the performance of land surface model simulations. Although different types of RWU functions have been adopted in land surface models, there is no evidence as to which scheme most applicable to maize farmland ecosystems. Based on the 2007-09 data collected at the farmland ecosystem field station in Jinzhou, the RWU function in the Common Land Model (CoLM) was optimized with scheme options in light of factors determining whether roots absorb water from a certain soil layer ( W x ) and whether the baseline cumulative root efficiency required for maximum plant transpiration ( W c ) is reached. The sensibility of the parameters of the optimization scheme was investigated, and then the effects of the optimized RWU function on water and heat flux simulation were evaluated. The results indicate that the model simulation was not sensitive to W x but was significantly impacted by W c . With the original model, soil humidity was somewhat underestimated for precipitation-free days; soil temperature was simulated with obvious interannual and seasonal differences and remarkable underestimations for the maize late-growth stage; and sensible and latent heat fluxes were overestimated and underestimated, respectively, for years with relatively less precipitation, and both were simulated with high accuracy for years with relatively more precipitation. The optimized RWU process resulted in a significant improvement of CoLM's performance in simulating soil humidity, temperature, sensible heat, and latent heat, for dry years. In conclusion, the optimized RWU scheme available for the CoLM model is applicable to the simulation of water and heat flux for maize farmland ecosystems in arid areas.

  4. A New Method to Determine Central Wavelength and Optimal Bandwidth for Predicting Plant Nitrogen Uptake in Winter Wheat

    Institute of Scientific and Technical Information of China (English)

    YAO Xin-feng; YAO Xia; TIAN Yong-chao; NI Jun; LIU Xiao-jun; CAO Wei-xing; ZHU Yan

    2013-01-01

    Plant nitrogen (N) uptake is a good indicator of cropNstatus. In this study, a new method was designed to determine the central wavelength, optimal bandwidth and vegetation indices for predicting plantNuptake (gNm-2) in winter wheat (Triticum aestivum L.). The data were collected from the ground-based hyperspectral reflectance measurements in eight field experiments on winter wheat of different years, eco-sites, varieties,Nrates, sowing dates, and densities. The plantNuptake index (PNUI) based on NDVI of 807 nm combined with 736 nm was selected as the optimal vegetation index, and a linear model was developed with R2 of 0.870 and RMSE of 1.546 gNm-2 for calibration, and R2 of 0.834, RMSE of 1.316 gNm-2, slope of 0.934, and intercept of 0.001 for validation. Then, the effect of the bandwidth of central wavelengths on model performance was determined based on the interaction between central wavelength and bandwidth expansion. The results indicated that the optimal bandwidth varies with the changes of the central wavelength and with the interaction between the two bands in one vegetation index. These findings are important for prediction and diagnosis of plantNuptake more precise and accurate in crop management.

  5. Optimal piezo-electro-mechanical coupling to control plate vibrations

    CERN Document Server

    Alessandroni, S; Frezza, F

    2010-01-01

    A new way of coupling electrical and mechanical waves, using piezoelectric effect, is presented here. Since the energy exchange between two systems supporting wave propagation is maximum when their evolution is governed by similar equations, hence, an optimal electromechanical coupling is obtained by designing an electric network which is "analog" to the mechanical structure to be controlled. In this paper, we exploit this idea to enhance the coupling, between a Kirchhoff-Love plate and one possible synthesis of its circuital analog, as obtained by means of a set of piezoelectric actuators uniformly distributed upon the plate. It is shown how this approach allows for an optimal energy exchange between the mechanic and the electric forms independent of the modal evolution of the structure. Moreover, we show how an efficient electric dissipation of the mechanical energy can be obtained adding dissipative elements in the electric network.

  6. Mechanical design and optimal control of humanoid robot (TPinokio)

    OpenAIRE

    Teck Chew Wee

    2014-01-01

    The mechanical structure and the control of the locomotion of bipedal humanoid is an important and challenging domain of research in bipedal robots. Accurate models of the kinematics and dynamics of the robot are essential to achieve bipedal locomotion. Toe-foot walking produces a more natural and faster walking speed and it is even possible to perform stretch knee walking. This study presents the mechanical design of a toe-feet bipedal, TPinokio and the implementation of some optimal walking...

  7. Exploring chemical reaction mechanisms through harmonic Fourier beads path optimization.

    Science.gov (United States)

    Khavrutskii, Ilja V; Smith, Jason B; Wallqvist, Anders

    2013-10-28

    Here, we apply the harmonic Fourier beads (HFB) path optimization method to study chemical reactions involving covalent bond breaking and forming on quantum mechanical (QM) and hybrid QM∕molecular mechanical (QM∕MM) potential energy surfaces. To improve efficiency of the path optimization on such computationally demanding potentials, we combined HFB with conjugate gradient (CG) optimization. The combined CG-HFB method was used to study two biologically relevant reactions, namely, L- to D-alanine amino acid inversion and alcohol acylation by amides. The optimized paths revealed several unexpected reaction steps in the gas phase. For example, on the B3LYP∕6-31G(d,p) potential, we found that alanine inversion proceeded via previously unknown intermediates, 2-iminopropane-1,1-diol and 3-amino-3-methyloxiran-2-ol. The CG-HFB method accurately located transition states, aiding in the interpretation of complex reaction mechanisms. Thus, on the B3LYP∕6-31G(d,p) potential, the gas phase activation barriers for the inversion and acylation reactions were 50.5 and 39.9 kcal∕mol, respectively. These barriers determine the spontaneous loss of amino acid chirality and cleavage of peptide bonds in proteins. We conclude that the combined CG-HFB method further advances QM and QM∕MM studies of reaction mechanisms.

  8. Quasivelocities and Optimal Control for Underactuated Mechanical Systems

    CERN Document Server

    Colombo, L

    2010-01-01

    This paper is concerned with the application of the theory of quasivelocities for optimal control for underactuated mechanical systems. Using this theory, we convert the original problem in a variational second-order lagrangian system subjected to constraints. The equations of motion are geometrically derived using an adaptation of the classical Skinner and Rusk formalism.

  9. Quasivelocities and Optimal Control for underactuated Mechanical Systems

    Science.gov (United States)

    Colombo, L.; de Diego, D. Martín

    2010-07-01

    This paper is concerned with the application of the theory of quasivelocities for optimal control for underactuated mechanical systems. Using this theory, we convert the original problem in a variational second-order lagrangian system subjected to constraints. The equations of motion are geometrically derived using an adaptation of the classical Skinner and Rusk formalism.

  10. The mechanism of cumene hydroperoxide-dependent lipid peroxidation: the significance of oxygen uptake.

    Science.gov (United States)

    Weiss, R H; Estabrook, R W

    1986-11-15

    The addition of limiting amounts of cumene hydroperoxide to rat liver microsomes prepared from phenobarbital-treated rats resulted in the rapid uptake of molecular oxygen, the formation of thiobarbituric acid reactive products, and the loss of hydroperoxide over a similar time course. Maximal activity was observed at pH 7-8. The addition of cumene hydroperoxide to boiled microsomes did not initiate oxygen uptake or produce thiobarbituric acid reactive products. Oxygen uptake was required for the formation of thiobarbituric acid reactive products, but not for the loss of hydroperoxide. The extent of oxygen uptake and thiobarbituric acid reactive product formation was linearly dependent on the concentration of cumene hydroperoxide and independent of the amount of microsomes. For each nanomole of cumene hydroperoxide utilized, 1.5 nmol of oxygen was consumed and 0.11 nmol of thiobarbituric acid reactive products was formed. In addition, a saturable reaction having a high affinity for cumene hydroperoxide was observed that was associated with little or no oxygen uptake and thiobarbituric acid reactive product formation. Butylated hydroxytoluene at substoichiometric concentrations inhibited the extents and initial rates of oxygen uptake and thiobarbituric acid reactive product formation, indicating that cumene hydroperoxide-dependent lipid peroxidation may be an autocatalytic free radical process.

  11. Optimal Motion Planning for Differentially Flat Underactuated Mechanical Systems

    Institute of Scientific and Technical Information of China (English)

    HE Guangping; GENG Zhiyong

    2009-01-01

    Underactuated mechanical system has less independent inputs than the degrees of freedom(DOF) of the mechanism. The energy efficiency of this class of mechanical systems is an essential problem in practice. On the basis of the sufficient and necessary condition that concludes a single input nonlinear system is differentially flat, it is shown that the flat output of the single input tmderactuated mechanical system can be obtained by finding a smooth output function such that the relative degree of the system equals to the dimension of the state space. If the fiat output of the underactuated system can be solved explicitly, and by constructing a smooth curve with satisfying given boundary conditions in flat output space, an energy efficiency optimization method is proposed for the motion planning of the differentially fiat underactuated mechanical systems. The inertia wheel pendulum is used to verify the proposed optimization method, and some numerical simulations show that the presented optimal motion planning method can efficaciously reduce the energy cost for given control tasks.

  12. Design optimization of a twist compliant mechanism with nonlinear stiffness

    Science.gov (United States)

    Tummala, Y.; Frecker, M. I.; Wissa, A. A.; Hubbard, J. E., Jr.

    2014-10-01

    A contact-aided compliant mechanism called a twist compliant mechanism (TCM) is presented in this paper. This mechanism has nonlinear stiffness when it is twisted in both directions along its axis. The inner core of the mechanism is primarily responsible for its flexibility in one twisting direction. The contact surfaces of the cross-members and compliant sectors are primarily responsible for its high stiffness in the opposite direction. A desired twist angle in a given direction can be achieved by tailoring the stiffness of a TCM. The stiffness of a compliant twist mechanism can be tailored by varying thickness of its cross-members, thickness of the core and thickness of its sectors. A multi-objective optimization problem with three objective functions is proposed in this paper, and used to design an optimal TCM with desired twist angle. The objective functions are to minimize the mass and maximum von-Mises stress observed, while minimizing or maximizing the twist angles under specific loading conditions. The multi-objective optimization problem proposed in this paper is solved for an ornithopter flight research platform as a case study, with the goal of using the TCM to achieve passive twisting of the wing during upstroke, while keeping the wing fully extended and rigid during the downstroke. Prototype TCMs have been fabricated using 3D printing and tested. Testing results are also presented in this paper.

  13. Modeling and optimization of magnetostrictive actuator amplified by compliant mechanism

    Science.gov (United States)

    Niu, Muqing; Yang, Bintang; Yang, Yikun; Meng, Guang

    2017-09-01

    Magnetostrictive actuators are commonly used in precision engineering with the advantages of high resolution and fast response. Their limited strokes are always amplified by compliant mechanisms without wear and backlash. This paper proposes a hybrid model for the actuation system considering the coupling of the actuator and the amplifier. The magnetostrictive model, based on the Jiles-Atherton model, is related to the input stiffness of the amplifier when quantifying the magneto-mechanical effects, including stress-dependent magnetization, stress-dependent magnetostriction and ΔE effect. The compliant mechanism model aims at constructing the flexibility matrix with the amplification ratio and input stiffness related to the spring factor of the load. The deformation and structural stress of the amplifier are also dependent on the output strain of magnetostrictive material. Experiments under both free load and spring load conditions have been done to verify the effectiveness of the hybrid model. The proposed model is suitable for parameter optimization and the performance indicators can be precisely quantified. Optimization based on hybrid model is more preferred than optimizing the actuator and amplifier independently for maximum output displacement. Furthermore, ‘stiffness match principle’ is no longer applicable when considering ΔE effect, and the optimal external stiffness problem can be numerically solved by the hybrid model for maximum output energy of magnetostrictive material.

  14. The novel albumin-chitosan core-shell nanoparticles for gene delivery: preparation, optimization and cell uptake investigation

    Science.gov (United States)

    Karimi, Mahdi; Avci, Pinar; Mobasseri, Rezvan; Hamblin, Michael R.; Naderi-Manesh, Hossein

    2013-05-01

    Natural polymers and proteins such as chitosan (CS) and albumin (Alb) have recently attracted much attention both in drug delivery and gene delivery. The underlying rationale is their unique properties such as biodegradability, biocompatibility and controlled release. This study aimed to prepare novel albumin-chitosan-DNA (Alb-CS-DNA) core-shell nanoparticles as a plasmid delivery system and find the best conditions for their preparation. Phase separation method and ionic interaction were used for preparation of Alb nanoparticles and Alb-CS-DNA core-shell nanoparticles, respectively. The effects of three important independent variables (1) CS/Alb mass ratio, (2) the ratios of moles of the amine groups of cationic polymers to those of the phosphate groups of DNA (N/P ratio), and (3) Alb concentration, on the nanoparticle size and loading efficiency of the plasmid were investigated and optimized through Box-Behnken design of response surface methodology (RSM). The optimum conditions were found to be CS/Alb mass ratio = 3, N/P ratio = 8.24 and Alb concentration = 0.1 mg/mL. The most critical factors for the size of nanoparticles and loading efficiency were Alb concentration and N/P ratio. The optimized nanoparticles had an average size of 176 ± 3.4 nm and loading efficiency of 80 ± 3.9 %. Cytotoxicity experiments demonstrated that the prepared nanoparticles were not toxic. The high cellular uptake of nanoparticles ( 85 %) was shown by flow cytometry and fluorescent microscopy.

  15. The novel albumin-chitosan core-shell nanoparticles for gene delivery: preparation, optimization and cell uptake investigation

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, Mahdi [Tarbiat Modares University, Department of Nanobiotechnology, Faculty of Biological Sciences (Iran, Islamic Republic of); Avci, Pinar [Massachusetts General Hospital, Wellman Center for Photomedicine (United States); Mobasseri, Rezvan [Tarbiat Modares University, Department of Nanobiotechnology, Faculty of Biological Sciences (Iran, Islamic Republic of); Hamblin, Michael R. [Massachusetts General Hospital, Wellman Center for Photomedicine (United States); Naderi-Manesh, Hossein, E-mail: naderman@modares.ac.ir [Tarbiat Modares University, Department of Nanobiotechnology, Faculty of Biological Sciences (Iran, Islamic Republic of)

    2013-05-15

    Natural polymers and proteins such as chitosan (CS) and albumin (Alb) have recently attracted much attention both in drug delivery and gene delivery. The underlying rationale is their unique properties such as biodegradability, biocompatibility and controlled release. This study aimed to prepare novel albumin-chitosan-DNA (Alb-CS-DNA) core-shell nanoparticles as a plasmid delivery system and find the best conditions for their preparation. Phase separation method and ionic interaction were used for preparation of Alb nanoparticles and Alb-CS-DNA core-shell nanoparticles, respectively. The effects of three important independent variables (1) CS/Alb mass ratio, (2) the ratios of moles of the amine groups of cationic polymers to those of the phosphate groups of DNA (N/P ratio), and (3) Alb concentration, on the nanoparticle size and loading efficiency of the plasmid were investigated and optimized through Box-Behnken design of response surface methodology (RSM). The optimum conditions were found to be CS/Alb mass ratio = 3, N/P ratio = 8.24 and Alb concentration = 0.1 mg/mL. The most critical factors for the size of nanoparticles and loading efficiency were Alb concentration and N/P ratio. The optimized nanoparticles had an average size of 176 {+-} 3.4 nm and loading efficiency of 80 {+-} 3.9 %. Cytotoxicity experiments demonstrated that the prepared nanoparticles were not toxic. The high cellular uptake of nanoparticles ({approx}85 %) was shown by flow cytometry and fluorescent microscopy.

  16. Optimal control of underactuated mechanical systems: A geometric approach

    Science.gov (United States)

    Colombo, Leonardo; Martín De Diego, David; Zuccalli, Marcela

    2010-08-01

    In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.

  17. Optimal Control of Underactuated Mechanical Systems: A Geometric Approach

    CERN Document Server

    Colombo, L; Zuccalli, M

    2009-01-01

    In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.

  18. Heterogeneity in the attachment and uptake mechanisms of the Legionnaires' disease bacterium, Legionella pneumophila, by protozoan hosts.

    Science.gov (United States)

    Harb, O S; Venkataraman, C; Haack, B J; Gao, L Y; Kwaik, Y A

    1998-01-01

    Invasion and intracellular replication of Legionella pneumophila within protozoa in the environment plays a major role in the transmission of Legionnaires' disease. Intracellular replication of L. pneumophila within protozoa occurs in a rough endoplasmic reticulum (RER)-surrounded phagosome (Y. Abu Kwaik, Appl. Environ. Microbiol. 62:2022-2028, 1996). Since the subsequent fate of many intracellular pathogens is determined by the route of entry, we compared the mechanisms of attachment and subsequent uptake of L. pneumophila by the two protozoa Hartmannella vermiformis and Acanthamoeba polyphaga. Our data provide biochemical and genetic evidence that the mechanisms of attachment and subsequent uptake of L. pneumophila by the two protozoan hosts are, in part, different. First, uptake of L. pneumophila by H. vermiformis is completely blocked by the monovalent sugars galactose and N-acetyl-D-galactosamine, but these sugars partially blocked A. polyphaga. Second, attachment of L. pneumophila to H. vermiformis is associated with a time-dependent and reversible tyrosine dephosphorylation of multiple host proteins. In contrast, only a slight dephosphorylation of a 170-kDa protein of A. polyphaga is detected upon infection. Third, synthesis of H. vermiformis proteins but not of A. polyphaga proteins is required for uptake of L. pneumophila. Fourth, we have identified L. pneumophila mutants that are severely defective in attachment to A. polyphaga but which exhibit minor reductions in attachment to H. vermiformis and, thus, provide a genetic basis for the difference in mechanisms of attachment to both protozoa. The data indicate a remarkable adaptation of L. pneumophila to attach and invade different protozoan hosts by different mechanisms, yet invasion is followed by a remarkably similar intracellular replication within a RER-surrounded phagosome and subsequent killing of the host cell.

  19. TOPOLOGY OPTIMIZATION OF MULTIPLE INPUTS AND MULTIPLE OUTPUTS COMPLIANT MECHANISMS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xianmin; OUYANG Gaofei; WANG Hua

    2007-01-01

    An optimal topology design method for multiple inputs and multiple outputs compliant micro-manipulation system is presented. Firstly, the topology design problem is posed in terms of a multiple inputs load and several specified output deflections. The compliance and stiffness of the system are expressed by the mutual potential energy and strain energy, respectively, which can be controlled by a multi-criteria objective function. Secondly, based on the optimality criteria method, a model solution algorithm is presented. Finally, a numerical example is presented to show the validity of the presented technique. The optimal topology of a 4 inputs and 4 outputs compliant mechanism is obtained by using the method, and the corresponding micro-positioning stage system is further designed.

  20. Nanocarriers for optimizing the balance between interfollicular permeation and follicular uptake of topically applied clobetasol to minimize adverse effects.

    Science.gov (United States)

    Mathes, C; Melero, A; Conrad, P; Vogt, T; Rigo, L; Selzer, D; Prado, W A; De Rossi, C; Garrigues, T M; Hansen, S; Guterres, S S; Pohlmann, A R; Beck, R C R; Lehr, C-M; Schaefer, U F

    2016-02-10

    The treatment of various hair disorders has become a central focus of good dermatologic patient care as it affects men and women all over the world. For many inflammatory-based scalp diseases, glucocorticoids are an essential part of treatment, even though they are known to cause systemic as well as local adverse effects when applied topically. Therefore, efficient targeting and avoidance of these side effects are of utmost importance. Optimizing the balance between drug release, interfollicular permeation, and follicular uptake may allow minimizing these adverse events and simultaneously improve drug delivery, given that one succeeds in targeting a sustained release formulation to the hair follicle. To test this hypothesis, three types of polymeric nanocarriers (nanospheres, nanocapsules, lipid-core nanocapsules) for the potent glucocorticoid clobetasol propionate (CP) were prepared. They all exhibited a sustained release of drug, as was desired. The particles were formulated as a dispersion and hydrogel and (partially) labeled with Rhodamin B for quantification purposes. Follicular uptake was investigated using the Differential Stripping method and was found highest for nanocapsules in dispersion after application of massage. Moreover, the active ingredient (CP) as well as the nanocarrier (Rhodamin B labeled polymer) recovered in the hair follicle were measured simultaneously, revealing an equivalent uptake of both. In contrast, only negligible amounts of CP could be detected in the hair follicle when applied as free drug in solution or hydrogel, regardless of any massage. Skin permeation experiments using heat-separated human epidermis mounted in Franz Diffusion cells revealed equivalent reduced transdermal permeability for all nanocarriers in comparison to application of the free drug. Combining these results, nanocapsules formulated as an aqueous dispersion and applied by massage appeare to be a good candidate to maximize follicular targeting and minimize drug

  1. Structural dependence of in vitro cytotoxicity, oxidative stress and uptake mechanisms of poly(propylene imine) dendritic nanoparticles.

    Science.gov (United States)

    Khalid, Humza; Mukherjee, Sourav Prasanna; O'Neill, Luke; Byrne, Hugh J

    2016-03-01

    The in vitro cytotoxic and intracellular oxidative stress responses to exposure to poly(propylene imine) (PPI) dendritic nanoparticles of increasing generation (number of repeated branching cycles) (G0-G4) were assessed in an immortal non-cancerous human keratinocyte cell line (HaCaT). Confocal fluorescence microscopy with organelle staining was used to explore the uptake and intracellular trafficking mechanisms. A generation- and dose-dependent cytotoxic response was observed, increasing according to generation and, therefore, number of surface amino groups. A comparison of the cytotoxic response of G4 PPI and the related G4 poly(amido amine) dendrimer indicates that the PPI with the same number of surface amino groups elicits a significantly higher cytotoxic response. The trend of cytotoxicity versus dendrimer generation and, therefore, size is discontinuous in the region of G2, however, indicating a difference in uptake mechanism for higher compared to lower generations. Whereas the higher generations elicit an oxidative stress response at short exposure times, the lower generations indicate an antioxidant response. Confocal microscopy indicates that, whereas they are prominent at early exposure times for the larger PPI dendrimers, no evidence of early stage endosomes was observed for lower generations of PPI. The results are consistent with an alternative uptake mechanism of physical diffusion across the semipermeable cell membrane for the lower generation dendrimers and are discussed in terms of their implications for predictive models for nanotoxicology and design strategies for nanomedical applications.

  2. Electron tomography characterization of hemoglobin uptake in Plasmodium chabaudi reveals a stage-dependent mechanism for food vacuole morphogenesis.

    Science.gov (United States)

    Wendt, Camila; Rachid, Rachel; de Souza, Wanderley; Miranda, Kildare

    2016-05-01

    In the course of their intraerythrocytic development, malaria parasites incorporate and degrade massive amounts of the host cell cytoplasm. This mechanism is essential for parasite development and represents a physiological step used as target for many antimalarial drugs; nevertheless, the fine mechanisms underlying these processes in Plasmodium species are still under discussion. Here, we studied the events of hemoglobin uptake and hemozoin nucleation in the different stages of the intraerythrocytic cycle of the murine malaria parasite Plasmodium chabaudi using transmission electron tomography of cryofixed and freeze-substituted cells. The results showed that hemoglobin uptake in P. chabaudi starts at the early ring stage and is present in all developmental stages, including the schizont stage. Hemozoin nucleation occurs near the membrane of small food vacuoles. At the trophozoite stage, food vacuoles are found closely localized to cytostomal tubes and mitochondria, whereas in the schizont stage, we observed a large food vacuole located in the central portion of the parasite. Taken together, these results provide new insights into the mechanisms of hemoglobin uptake and degradation in rodent malaria parasites.

  3. Reliability Simulation and Design Optimization for Mechanical Maintenance

    Institute of Scientific and Technical Information of China (English)

    LIU Deshun; HUANG Liangpei; YUE Wenhui; XU Xiaoyan

    2009-01-01

    Reliability model of a mechanical product system will be newly reconstructed and maintenance cost will increase because failed parts can be replaced with new components during service, which should be accounted for in system design. In this paper, a reliability model and reliability-based design optimization methodology for maintenance are presented. First, based on the time-to-failure density function of the part of the system, the age distributions of all parts of the system during service are investigated, a reliability model of the mechanical system for maintenance is developed. Then, reliability simulations of the systems with Weibull probability density functions are performed, the system minimum reliability and steady reliability for maintenance are defined based on reliability simulation during the life cycle of the system. Thirdly, a maintenance cost model is developed based on replacement rates of the parts, a reliability-based design optimization model for maintenance is presented, in which total life cycle cost is considered as design objective and system reliability as design constrain. Finally, the reliability-based design optimization methodology for maintenance is used to design of a link ring for the chain conveyor, which shows that optimal design with the lowest maintenance cost can be obtained, and minimum reliability and steady reliability of the system can satisfy requirement of system reliability during service of the chain conveyor.

  4. Visual Servicing for Optimization of Anticancer Drug Uptake in Human Breast Cancer

    Science.gov (United States)

    2001-09-01

    sciences of the united states of america, 1991. 88(7): p. 2702-6. 15. Dickson, R.B. and M.E. Lippman, Cancer: principles and practice of oncology ...Cancer of the Breast, ed. V.T. Devita , Jr., Hellman, S., and Rosenberg, S.A. 1997, Philadelphia: Lippincott- Raven. Ch. 36, pp. 1541-1557. 16. Cotter...mechanism of drug resistance. hematology/ oncology clinics of north america, 1995. 9(2): p. 451-73. 22. Hengartner, M.O., The biochemistry of apoptosis

  5. Optimization of the transmission mechanism for wireless TCP

    Institute of Scientific and Technical Information of China (English)

    QU Zhao-wei; ZHANG Juan

    2008-01-01

    A novel method which can detect the possible handoffsfor mobile nodes is proposed in this article. The method can bedeployed on mobile nodes. So when a possible handoff occurs,mobile nodes can detect and take some necessary actions intime. In this study, the method is also used to optimize thetransmission mechanism of Q-TCP. Moreover, the simulationresults show that Q-TCP can provide better quality of service(QoS) for mobile nodes when they are moving among differentagents.

  6. Uptake mechanisms of selenium oxyanions during the ferrihydrite-hematite recrystallization

    Science.gov (United States)

    Börsig, Nicolas; Scheinost, Andreas C.; Shaw, Samuel; Schild, Dieter; Neumann, Thomas

    2017-06-01

    Se is an essential nutrient at trace levels, but also a toxic environmental contaminant at higher concentrations. The mobility of the trace element Se in natural environments is mainly controlled by the occurrence of the highly soluble Se oxyanions - selenite [Se(IV)] and selenate [Se(VI)] - and their interaction with geological materials. Since iron oxides are ubiquitous in nature, many previous studies investigated Se retention by adsorption onto iron oxides. However, little is known about the retention of Se oxyanions during the formation process of iron oxides. In this paper, we therefore studied the immobilization of Se oxyanions during the crystallization of hematite from ferrihydrite. In coprecipitation studies, hematite was synthesized by the precipitation and aging of ferrihydrite in an oxidized Se(IV)- or Se(VI)-containing system (pH 7.5). Hydrochemical data of these batch experiments revealed the complete uptake of all available Se(IV) up to initial concentrations of c(Se)0 = 10-3 mol/L (m/V ratio = 9.0 g/L), while the retention of Se(VI) was low (max. 15% of c(Se)0). In case of high initial Se(IV) concentrations, the results also demonstrated that the interaction of Se with ferrihydrite can affect the type of the final transformation product. Comparative adsorption studies, performed at identical conditions, allowed a distinction between pure adsorption and coprecipitation and showed a significantly higher Se retention by coprecipitation than by adsorption. Desorption studies indicated that Se coprecipitation leads to the occurrence of a resistant, non-desorbable Se fraction. According to time-resolved studies of Se(IV) or Se(VI) retention during the hematite formation and detailed spectroscopic analyses (XPS, XAS), this fraction is the result of an incorporation process, which is not attributable to Fe-for-Se substitution or the Se occupation of vacancies. Se initially adsorbs to the ferrihydrite surface, but after the transformation of ferrihydrite

  7. Optimized reaction mechanism rate rules for ignition of normal alkanes

    KAUST Repository

    Cai, Liming

    2016-08-11

    The increasing demand for cleaner combustion and reduced greenhouse gas emissions motivates research on the combustion of hydrocarbon fuels and their surrogates. Accurate detailed chemical kinetic models are an important prerequisite for high fidelity reacting flow simulations capable of improving combustor design and operation. The development of such models for many new fuel components and/or surrogate molecules is greatly facilitated by the application of reaction classes and rate rules. Accurate and versatile rate rules are desirable to improve the predictive accuracy of kinetic models. A major contribution in the literature is the recent work by Bugler et al. (2015), which has significantly improved rate rules and thermochemical parameters used in kinetic modeling of alkanes. In the present study, it is demonstrated that rate rules can be used and consistently optimized for a set of normal alkanes including n-heptane, n-octane, n-nonane, n-decane, and n-undecane, thereby improving the predictive accuracy for all the considered fuels. A Bayesian framework is applied in the calibration of the rate rules. The optimized rate rules are subsequently applied to generate a mechanism for n-dodecane, which was not part of the training set for the optimized rate rules. The developed mechanism shows accurate predictions compared with published well-validated mechanisms for a wide range of conditions.

  8. Exercise and Type 2 Diabetes: Molecular Mechanisms Regulating Glucose Uptake in Skeletal Muscle

    Science.gov (United States)

    Stanford, Kristin I.; Goodyear, Laurie J.

    2014-01-01

    Exercise is a well-established tool to prevent and combat type 2 diabetes. Exercise improves whole body metabolic health in people with type 2 diabetes, and adaptations to skeletal muscle are essential for this improvement. An acute bout of exercise increases skeletal muscle glucose uptake, while chronic exercise training improves mitochondrial…

  9. Element uptake, accumulation, and resorption in leaves of mangrove species with different mechanisms of salt regulation

    Science.gov (United States)

    E. Medina; W. Fernandez; F. Barboza

    2015-01-01

    Element uptake from substrate and resorption capacity of nutrients before leaf shedding are frequently species-specific and difficult to determine in natural settings. We sampled populations of Rhizophora mangle (salt-excluding species) and Laguncularia racemosa (salt-secreting species) in a coastal lagoon in the upper section of the Maracaibo strait in western...

  10. Exercise and Type 2 Diabetes: Molecular Mechanisms Regulating Glucose Uptake in Skeletal Muscle

    Science.gov (United States)

    Stanford, Kristin I.; Goodyear, Laurie J.

    2014-01-01

    Exercise is a well-established tool to prevent and combat type 2 diabetes. Exercise improves whole body metabolic health in people with type 2 diabetes, and adaptations to skeletal muscle are essential for this improvement. An acute bout of exercise increases skeletal muscle glucose uptake, while chronic exercise training improves mitochondrial…

  11. The mechanism of NH3 and SO2 uptake by leaves and its physiological effects.

    NARCIS (Netherlands)

    Hove, van L.W.A.

    1989-01-01

    The relation between uptake of atmospheric ammonia (NH 3 ) and sulphur dioxide (SO 2 ) by individual leaves, photosynthesis and stomatal conductance was examined. The experiments were carried out with bean plants ( Phaseolus vulgari

  12. Mechanism of Copper Uptake from Blood Plasma Ceruloplasmin by Mammalian Cells.

    Directory of Open Access Journals (Sweden)

    Danny Ramos

    Full Text Available Ceruloplasmin, the main copper binding protein in blood plasma, has been of particular interest for its role in efflux of iron from cells, but has additional functions. Here we tested the hypothesis that it releases its copper for cell uptake by interacting with a cell surface reductase and transporters, producing apoceruloplasmin. Uptake and transepithelial transport of copper from ceruloplasmin was demonstrated with mammary epithelial cell monolayers (PMC42 with tight junctions grown in bicameral chambers, and purified human (64Cu-labeled ceruloplasmin secreted by HepG2 cells. Monolayers took up virtually all the (64Cu over 16h and secreted half into the apical (milk fluid. This was partly inhibited by Ag(I. The (64Cu in ceruloplasmin purified from plasma of (64Cu-injected mice accumulated linearly in mouse embryonic fibroblasts (MEFs over 3-6h. Rates were somewhat higher in Ctr1+/+ versus Ctr1-/- cells, and 3-fold lower at 2 °C. The ceruloplasmin-derived (64Cu could not be removed by extensive washing or trypsin treatment, and most was recovered in the cytosol. Actual cell copper (determined by furnace atomic absorption increased markedly upon 24h exposure to holoceruloplasmin. This was accompanied by a conversion of holo to apoceruloplasmin in the culture medium and did not occur during incubation in the absence of cells. Four different endocytosis inhibitors failed to prevent 64Cu uptake from ceruloplasmin. High concentrations of non-radioactive Cu(II- or Fe(III-NTA (substrates for cell surface reductases, or Cu(I-NTA (to compete for transporter uptake almost eliminated uptake of (64Cu from ceruloplasmin. MEFs had cell surface reductase activity and expressed Steap 2 (but not Steaps 3 and 4 or dCytB. However, six-day siRNA treatment was insufficient to reduce activity or uptake. We conclude that ceruloplasmin is a circulating copper transport protein that may interact with Steap2 on the cell surface, forming apoceruloplasmin, and Cu(I that

  13. Synthesis, uptake mechanism characterization and biological evaluation of {sup 18}F labeled fluoroalkyl phenylalanine analogs as potential PET imaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Wang Limin [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Qu Wenchao; Lieberman, Brian P.; Ploessl, Karl [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Kung, Hank F., E-mail: kunghf@gmail.co [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2011-01-15

    Introduction: Amino acids based tracers represent a promising class of tumor metabolic imaging agents with successful clinical applications. Two new phenylalanine derivatives, p-(2-[{sup 18}F]fluoroethyl)-L-phenylalanine (FEP, [{sup 18}F]2) and p-(3-[{sup 18}F]fluoropropyl)-L-phenylalanine (FPP, [{sup 18}F]3) were synthesized and evaluated in comparison to clinically utilized O-(2-[{sup 18}F]fluoroethyl)-L-tyrosine (FET, [{sup 18}F]1). Methods: FEP ([{sup 18}F]2) and FPP ([{sup 18}F]3) were successfully synthesized by a rapid and efficient two-step nucleophilic fluorination of tosylate precursors and deprotection reaction. In vitro cell uptake studies were carried out in 9L glioma cells. In vivo studies, 9L tumor xenografts were implanted in Fisher 344 rats. Results: FEP ([{sup 18}F]2) and FPP ([{sup 18}F]3) could be efficiently labeled within 90 min with good enantiomeric purity (>95%), good yield (11-37%) and high specific activity (21-69 GBq/{mu}mol). Cell uptake studies showed FEP had higher uptake than FPP as well as reference ligand FET ([{sup 18}F]1). Uptake mechanism studies suggested that FEP is a selective substrate for system L and prefers its subtype LAT1. In vivo biodistribution studies demonstrated FEP had specific accumulation in tumor cells and tumor to background ratio reached 1.45 at 60 min. Small animal positron emission tomography (PET) imaging studies showed FEP was comparable to FET for imaging rats bearing 9L tumor model. FEP had high uptake in 9L tumor compared to surrounding tissue and was quickly excreted through urinary tract. Conclusion: Biological evaluations indicate that FEP ([{sup 18}F]2) is a potential useful tracer for tumor imaging with PET.

  14. Design Optimization of Mechanical Components Using an Enhanced Teaching-Learning Based Optimization Algorithm with Differential Operator

    Directory of Open Access Journals (Sweden)

    B. Thamaraikannan

    2014-01-01

    Full Text Available This paper studies in detail the background and implementation of a teaching-learning based optimization (TLBO algorithm with differential operator for optimization task of a few mechanical components, which are essential for most of the mechanical engineering applications. Like most of the other heuristic techniques, TLBO is also a population-based method and uses a population of solutions to proceed to the global solution. A differential operator is incorporated into the TLBO for effective search of better solutions. To validate the effectiveness of the proposed method, three typical optimization problems are considered in this research: firstly, to optimize the weight in a belt-pulley drive, secondly, to optimize the volume in a closed coil helical spring, and finally to optimize the weight in a hollow shaft. have been demonstrated. Simulation result on the optimization (mechanical components problems reveals the ability of the proposed methodology to find better optimal solutions compared to other optimization algorithms.

  15. Controlling the feed rate of propanol to optimize erythromycin fermentation by on-line capacitance and oxygen uptake rate measurement.

    Science.gov (United States)

    Guo, Qian; Chu, Ju; Zhuang, Yingping; Gao, Yang

    2016-02-01

    The aim of the present study was to optimize the feeding proportion of glucose and propanol for erythromycin biosynthesis by real-time monitoring and exploring its limited ratio by the on-line multi-frequency permittivity measurement. It was found that the capacitance values were sensitive to the variation of biomass concentration and microbial morphology as well as the true state of cell growth. It was most favorable to both cell growth and secondary metabolism to keep the ratio of glucose to propanol at 4.3 (g/g). The specific growth rate calculated by the capacitance measurement correctly and accurately reflected the cell physiological state. An appropriate feed rate of propanol was crucial for cell growth and secondary metabolism, as well as to improve the quality of erythromycin-A. In addition, the erythromycin production titer (10,950 U/mL) was further enhanced by 4 % when the propanol feed was regulated by step-down strategy based on both OUR (oxygen uptake rate) and the on-line monitoring capacitance.

  16. Regional intracellular pH shift: a proposed new mechanism for radiopharmaceutical uptake in brain and other tissues.

    Science.gov (United States)

    Kung, H F; Blau, M

    1980-02-01

    This paper proposes a new mechanism for radiopharmaceutical uptake, which may be applicable to a variety of clinical studies. Many tissues and organs have low intracellular pH, either normally or as a result of various metabolic disturbances. We have developed a series of compounds that are neutral and lipid-soluble at blood pH. These molecules can diffuse freely into cells. In those regions where intracellular pH is low, they pick up a hydrogen ion and become charged. In this form they are no longer lipid-soluble and are trapped because they cannot diffuse out of the cell. Studies of the brain uptake of two compounds of this type, Se-75 labeled di-beta-(morpholinoethyl)-selenide (MOSE) and di-beta-(piperidinoethyl)-selenide (PIPSE), demonstrate the application of the principle.

  17. Optimal state discrimination and unstructured search in nonlinear quantum mechanics

    Science.gov (United States)

    Childs, Andrew M.; Young, Joshua

    2016-02-01

    Nonlinear variants of quantum mechanics can solve tasks that are impossible in standard quantum theory, such as perfectly distinguishing nonorthogonal states. Here we derive the optimal protocol for distinguishing two states of a qubit using the Gross-Pitaevskii equation, a model of nonlinear quantum mechanics that arises as an effective description of Bose-Einstein condensates. Using this protocol, we present an algorithm for unstructured search in the Gross-Pitaevskii model, obtaining an exponential improvement over a previous algorithm of Meyer and Wong. This result establishes a limitation on the effectiveness of the Gross-Pitaevskii approximation. More generally, we demonstrate similar behavior under a family of related nonlinearities, giving evidence that the ability to quickly discriminate nonorthogonal states and thereby solve unstructured search is a generic feature of nonlinear quantum mechanics.

  18. Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies.

    Science.gov (United States)

    Zhao, Fang-Jie; McGrath, Steve P; Meharg, Andrew A

    2010-01-01

    Arsenic (As) is an environmental and food chain contaminant. Excessive accumulation of As, particularly inorganic arsenic (As(i)), in rice (Oryza sativa) poses a potential health risk to populations with high rice consumption. Rice is efficient at As accumulation owing to flooded paddy cultivation that leads to arsenite mobilization, and the inadvertent yet efficient uptake of arsenite through the silicon transport pathway. Iron, phosphorus, sulfur, and silicon interact strongly with As during its route from soil to plants. Plants take up arsenate through the phosphate transporters, and arsenite and undissociated methylated As species through the nodulin 26-like intrinsic (NIP) aquaporin channels. Arsenate is readily reduced to arsenite in planta, which is detoxified by complexation with thiol-rich peptides such as phytochelatins and/or vacuolar sequestration. A range of mitigation methods, from agronomic measures and plant breeding to genetic modification, may be employed to reduce As uptake by food crops.

  19. Novel electromagnetism-like mechanism method for multiobjective optimization problems

    Institute of Scientific and Technical Information of China (English)

    Lixia Han,Shujuan Jiang,; Shaojiang Lan

    2015-01-01

    As a new-style stochastic algorithm, the electro-magnetism-like mechanism (EM) method gains more and more attention from many researchers in recent years. A novel model based on EM (NMEM) for multiobjective optimization problems is proposed, which regards the charge of al particles as the con-straints in the current population and the measure of the uniformity of non-dominated solutions as the objective function. The charge of the particle is evaluated based on the dominated concept, and its magnitude determines the direction of a force between two particles. Numerical studies are carried out on six complex test functions and the experimental results demonstrate that the pro-posed NMEM algorithm is a very robust method for solving the multiobjective optimization problems.

  20. Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: Mechanisms involved for lead

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, E., E-mail: eva.schreck@ensat.fr [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); Foucault, Y. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); STCM, Societe de Traitements Chimiques des Metaux, 30 Avenue de Fondeyre 31200 Toulouse (France); Sarret, G. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Sobanska, S. [LASIR (UMR CNRS 8516), Universite de Lille 1, Bat. C5, 59655 Villeneuve d' Ascq cedex (France); Cecillon, L. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Castrec-Rouelle, M. [Universite Pierre and Marie Curie (UPMC-Paris 6), Bioemco (Biogeochimie et Ecologie des Milieux Continentaux), Site Jussieu, Tour 56, 4 Place Jussieu, 75252 Paris cedex 05 (France); Uzu, G. [Laboratoire d' Aerologie (UMR 5560), OMP, UPS 14, Avenue Edouard Belin, 31400 Toulouse (France); GET (UMR 5563), IRD, 14, Avenue Edouard Belin, 31400 Toulouse (France); Dumat, C. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France)

    2012-06-15

    Fine and ultrafine metallic particulate matters (PMs) are emitted from metallurgic activities in peri-urban zones into the atmosphere and can be deposited in terrestrial ecosystems. The foliar transfer of metals and metalloids and their fate in plant leaves remain unclear, although this way of penetration may be a major contributor to the transfer of metals into plants. This study focused on the foliar uptake of various metals and metalloids from enriched PM (Cu, Zn, Cd, Sn, Sb, As, and especially lead (Pb)) resulting from the emissions of a battery-recycling factory. Metal and metalloid foliar uptake by various vegetable species, exhibiting different morphologies, use (food or fodder) and life-cycle (lettuce, parsley and rye-grass) were studied. The mechanisms involved in foliar metal transfer from atmospheric particulate matter fallout, using lead (Pb) as a model element was also investigated. Several complementary techniques (micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive X-ray microanalysis and time-of-flight secondary ion mass spectrometry) were used to investigate the localization and the speciation of lead in their edible parts, i.e. leaves. The results showed lead-enriched PM on the surface of plant leaves. Biogeochemical transformations occurred on the leaf surfaces with the formation of lead secondary species (PbCO{sub 3} and organic Pb). Some compounds were internalized in their primary form (PbSO{sub 4}) underneath an organic layer. Internalization through the cuticle or penetration through stomata openings are proposed as two major mechanisms involved in foliar uptake of particulate matter. - Graphical abstract: Overall picture of performed observations and mechanisms potentially involved in lead foliar uptake. Highlights: Black-Right-Pointing-Pointer Foliar uptake of metallic particulate matter (PM) is of environmental and health concerns. Black-Right-Pointing-Pointer The leaf morphology influences the adsorption

  1. Mechanical design and optimal control of humanoid robot (TPinokio

    Directory of Open Access Journals (Sweden)

    Teck Chew Wee

    2014-04-01

    Full Text Available The mechanical structure and the control of the locomotion of bipedal humanoid is an important and challenging domain of research in bipedal robots. Accurate models of the kinematics and dynamics of the robot are essential to achieve bipedal locomotion. Toe-foot walking produces a more natural and faster walking speed and it is even possible to perform stretch knee walking. This study presents the mechanical design of a toe-feet bipedal, TPinokio and the implementation of some optimal walking gait generation methods. The optimality in the gait trajectory is achieved by applying augmented model predictive control method and the pole-zero cancellation method, taken into consideration of a trade-off between walking speed and stability. The mechanism of the TPinokio robot is designed in modular form, so that its kinematics can be modelled accurately into a multiple point-mass system, its dynamics is modelled using the single and double mass inverted pendulum model and zero-moment-point concept. The effectiveness of the design and control technique is validated by simulation testing with the robot walking on flat surface and climbing stairs.

  2. Mechanical Properties Optimization of Fiber Reinforced Foam Concrete

    Directory of Open Access Journals (Sweden)

    Yu Lei

    2016-01-01

    Full Text Available 3 factors including fiber kind, fiber content and fiber mix-ability are selected to optimizing mechanical properties of foam concrete. By orthogonal experiment design, compression and flexural stress and strain of specimens from different fiber added ways were test. Range analysis and factor levels analysis show the best fiber added way. Test shows that fiber content is the most important factor to flexural stress. Next one is fiber kind and the third is fiber mix-ability. Fiber kind is the most important factor to stress curves. Fiber is not good for compression strength but good for flexural strength.

  3. CHINESE JOURNAL OF MECHANICAL ENGINEERING RELIABILITY AND OPTIMIZATION DESIGN OF NEW ROLLER ORIENTATION CLUTCH

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The mechanical reliability and optimization theory on the method of reliability-optimization design for the new roller orientation clutch is provided. The result of reliability-optimization design is compared with the result of the conventional design method.

  4. Uptake and phloem transport of glucose-fipronil conjugate in Ricinus communis involve a carrier-mediated mechanism.

    Science.gov (United States)

    Wu, Han-Xiang; Yang, Wen; Zhang, Zhi-Xiang; Huang, Ting; Yao, Guang-Kai; Xu, Han-Hong

    2012-06-20

    Some compounds containing glucose are absorbed via the monosaccharide transporters of the plasma membrane. A glucose-fipronil conjugate, N-[3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazol-5-yl]-1-(β-d-glucopyranosyl)-1H-1,2,3-triazole-4-methanamine (GTF), has been synthesized in our previous work. GTF exhibits moderate phloem mobility in Ricinus communis. In the current paper, we demonstrate that the uptake of GTF by Ricinus seedling cotyledon discs is partly mediated by an active carrier system (K(m)1 = 0.17 mM; V(max)1 = 2.2 nmol cm(-2) h(-1)). Four compounds [d-glucose, sucrose, phloridzin, and carbonyl cyanide m-chlorophenylhydrazone (CCCP)] were examined for their effect on GTF uptake. Phloridzin as well as CCCP markedly inhibit GTF uptake, and d-glucose weakly competes with it. The phloem transport of GTF in Ricinus seedlings is found to involve an active carrier-mediated mechanism that effectively contributes to the GTF phloem loading. The results prove that adding a glucose core is a reasonable and feasible approach to confer phloem mobility to fipronil by utilizing plant monosaccharide transporters.

  5. Correlation between mechanical stress by finite element analysis and 18F-fluoride PET uptake in hip osteoarthritis patients.

    Science.gov (United States)

    Hirata, Yasuhide; Inaba, Yutaka; Kobayashi, Naomi; Ike, Hiroyuki; Yukizawa, Yohei; Fujimaki, Hiroshi; Tezuka, Taro; Tateishi, Ukihide; Inoue, Tomio; Saito, Tomoyuki

    2015-01-01

    18F-fluoride positron emission tomography (18F-fluoride PET) is a functional imaging modality used primarily to detect increased bone metabolism. Increased 18F-fluoride PET uptake suggests an association between increased bone metabolism and load stress at the subchondral level. This study therefore examined the relationship between equivalent stress distribution calculated by finite element analysis and 18F-fluoride PET uptake in patients with hip osteoarthritis. The study examined 34 hips of 17 patients who presented to our clinic with hip pain, and were diagnosed with osteoarthritis or pre-osteoarthritis. The hips with trauma, infection, or bone metastasis of cancer were excluded. Three-dimensional models of each hip were created from computed tomography data to calculate the maximum equivalent stress by finite element analysis, which was compared with the maximum standardized uptake value (SUVmax) examined by 18F-fluoride PET. The SUVmax and equivalent stress were correlated (Spearman's rank correlation coefficient ρ=0.752), and higher equivalent stress values were noted in higher SUVmax patients. The correlation between SUVmax and maximum equivalent stress in osteoarthritic hips suggests the possibility that 18F-fluoride PET detect increased bone metabolism at sites of stress concentration. This study demonstrates the correlation between mechanical stress and bone remodeling acceleration in hip osteoarthritis.

  6. Customized evolutionary optimization procedure for generating minimum weight compliant mechanisms

    Science.gov (United States)

    Sharma, Deepak; Deb, Kalyanmoy; Kishore, N. N.

    2014-01-01

    In this article, a customized evolutionary optimization procedure is developed for generating minimum weight compliant mechanisms. A previously-suggested concept of multi-objectivization in which a helper objective is introduced in addition to the primary objective of the original single-objective optimization problem (SOOP) is used here. The helper objective is chosen in a way such that it is in conflict with the primary objective, thereby causing an evolutionary multi-objective optimization algorithm to maintain diversity in its population from one generation to another. The elitist non-dominated sorting genetic algorithm (NSGA-II) is customized with a domain-specific initialization strategy, a domain-specific crossover operator, and a domain-specific solution repairing strategy. To make the search process computationally tractable, the proposed methodology is made suitable for parallel computing. A local search methodology is applied on the evolved non-dominated solutions found by the above-mentioned modified NSGA-II to refine the solutions further. Two case studies for tracing curvilinear and straight-line paths are performed. Results demonstrate that solutions having smaller weight than the reference design solution obtained by SOOP are found by the proposed procedure. Interesting facts and observations brought out by the study are also narrated and conclusions of the study are made.

  7. Medicago truncatula increases its iron-uptake mechanisms in response to volatile organic compounds produced by Sinorhizobium meliloti.

    Science.gov (United States)

    Orozco-Mosqueda, Maria del Carmen; Macías-Rodríguez, Lourdes I; Santoyo, Gustavo; Farías-Rodríguez, Rodolfo; Valencia-Cantero, Eduardo

    2013-11-01

    Medicago truncatula represents a model plant species for understanding legume-bacteria interactions. M. truncatula roots form a specific root-nodule symbiosis with the nitrogen-fixing bacterium Sinorhizobium meliloti. Symbiotic nitrogen fixation generates high iron (Fe) demands for bacterial nitrogenase holoenzyme and plant leghemoglobin proteins. Leguminous plants acquire Fe via "Strategy I," which includes mechanisms such as rhizosphere acidification and enhanced ferric reductase activity. In the present work, we analyzed the effect of S. meliloti volatile organic compounds (VOCs) on the Fe-uptake mechanisms of M. truncatula seedlings under Fe-deficient and Fe-rich conditions. Axenic cultures showed that both plant and bacterium modified VOC synthesis in the presence of the respective symbiotic partner. Importantly, in both Fe-rich and -deficient experiments, bacterial VOCs increased the generation of plant biomass, rhizosphere acidification, ferric reductase activity, and chlorophyll content in plants. On the basis of our results, we propose that M. truncatula perceives its symbiont through VOC emissions, and in response, increases Fe-uptake mechanisms to facilitate symbiosis.

  8. Optimization and mechanism of surfactant accelerating leaching test

    Institute of Scientific and Technical Information of China (English)

    艾纯明; 吴爱祥; 王贻明; 侯春来

    2016-01-01

    To solve the problem of slow leaching speed of copper, surfactant was added into lixivium as leaching agent in the experiment. Based on physical chemistry and seepage flow mechanics, the leaching mechanics of surfactant was analyzed. The solution surface tension and surfactant adsorbing on the surface of ore have a significant impact on the surface wetting effect. With leaching rate for response, the study screened out three main factors by Plackett-Burman design method: the sulfuric acid concentration, surfactant concentration and temperature. Among these three factors, the surfactant concentration is the most important contributor to leaching rate. After obtaining the experiment center by the steepest ascent experiment, a continuous variable surface model was built by response surface methodology. By solving quadratic polynomial equation, optimal conditions for leaching were finally obtained as follows:the sulfuric acid concentration was 60 g/L, the surfactant concentration was 0.00914 mol/L, and the temperature was 45 °C. The leaching rate was 66.81%in the optimized leaching conditions, which was close to the predicted value, showing that regression result was good.

  9. Neural mechanism of optimal limb coordination in crustacean swimming.

    Science.gov (United States)

    Zhang, Calvin; Guy, Robert D; Mulloney, Brian; Zhang, Qinghai; Lewis, Timothy J

    2014-09-23

    A fundamental challenge in neuroscience is to understand how biologically salient motor behaviors emerge from properties of the underlying neural circuits. Crayfish, krill, prawns, lobsters, and other long-tailed crustaceans swim by rhythmically moving limbs called swimmerets. Over the entire biological range of animal size and paddling frequency, movements of adjacent swimmerets maintain an approximate quarter-period phase difference with the more posterior limbs leading the cycle. We use a computational fluid dynamics model to show that this frequency-invariant stroke pattern is the most effective and mechanically efficient paddling rhythm across the full range of biologically relevant Reynolds numbers in crustacean swimming. We then show that the organization of the neural circuit underlying swimmeret coordination provides a robust mechanism for generating this stroke pattern. Specifically, the wave-like limb coordination emerges robustly from a combination of the half-center structure of the local central pattern generating circuits (CPGs) that drive the movements of each limb, the asymmetric network topology of the connections between local CPGs, and the phase response properties of the local CPGs, which we measure experimentally. Thus, the crustacean swimmeret system serves as a concrete example in which the architecture of a neural circuit leads to optimal behavior in a robust manner. Furthermore, we consider all possible connection topologies between local CPGs and show that the natural connectivity pattern generates the biomechanically optimal stroke pattern most robustly. Given the high metabolic cost of crustacean swimming, our results suggest that natural selection has pushed the swimmeret neural circuit toward a connection topology that produces optimal behavior.

  10. Studies of iron-uptake mechanisms in two bacterial species of the shewanella genus adapted to middle-range (Shewanella putrefaciens) or antarctic (Shewanella gelidimarina) temperatures.

    Science.gov (United States)

    Pakchung, Amalie A H; Soe, Cho Z; Codd, Rachel

    2008-10-01

    Iron(III)-uptake mechanisms in bacteria indigenous to the Antarctic, which is the most Fe-deficient continent on Earth, have not been extensively studied. The cold-adapted, Antarctic bacterium, Shewanella gelidimarina, does not produce detectable levels of the siderophore, putrebactin, in the supernatant of Fe(III)-deprived cultures. This is distinct from the putrebactin-producing bacterium from the same genus, Shewanella putrefaciens, which is adapted to middle-range temperatures. The production of putrebactin by S. putrefaciens is optimal, when the pH value of the medium is 7.0. According to the strong positive response from whole cells in the Chrome Azurol S (CAS) agar diffusion assay, Shewanella gelidimarina appears to produce cell-associated siderophores. In the RP-HPLC trace of an Fe(III)-loaded extract from the cell-associated components of S. gelidimarina cultured in media with [Fe(III)] ca. 0 microM, a peak appears at [MeCN] ca. 77%, which decreases in intensity in a parallel experiment in which [Fe(III)] ca. 5 microM, and is barely detectable in Fe(III)-replete media ([Fe(III)] ca. 20 microM). The Fe(III)-dependence of this peak suggests that the attendant species, which is significantly more hydrophobic than putrebactin (RP-HPLC elution: [MeCN] ca. 14%), is associated with Fe(III)-management in S. gelidimarina. This study highlights the diversity in Fe(III)-uptake mechanisms in Shewanella species adapted to different environmental and thermal niches.

  11. Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: mechanisms involved for lead.

    Science.gov (United States)

    Schreck, E; Foucault, Y; Sarret, G; Sobanska, S; Cécillon, L; Castrec-Rouelle, M; Uzu, G; Dumat, C

    2012-06-15

    Fine and ultrafine metallic particulate matters (PMs) are emitted from metallurgic activities in peri-urban zones into the atmosphere and can be deposited in terrestrial ecosystems. The foliar transfer of metals and metalloids and their fate in plant leaves remain unclear, although this way of penetration may be a major contributor to the transfer of metals into plants. This study focused on the foliar uptake of various metals and metalloids from enriched PM (Cu, Zn, Cd, Sn, Sb, As, and especially lead (Pb)) resulting from the emissions of a battery-recycling factory. Metal and metalloid foliar uptake by various vegetable species, exhibiting different morphologies, use (food or fodder) and life-cycle (lettuce, parsley and rye-grass) were studied. The mechanisms involved in foliar metal transfer from atmospheric particulate matter fallout, using lead (Pb) as a model element was also investigated. Several complementary techniques (micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive X-ray microanalysis and time-of-flight secondary ion mass spectrometry) were used to investigate the localization and the speciation of lead in their edible parts, i.e. leaves. The results showed lead-enriched PM on the surface of plant leaves. Biogeochemical transformations occurred on the leaf surfaces with the formation of lead secondary species (PbCO(3) and organic Pb). Some compounds were internalized in their primary form (PbSO(4)) underneath an organic layer. Internalization through the cuticle or penetration through stomata openings are proposed as two major mechanisms involved in foliar uptake of particulate matter.

  12. Study of 223Ra uptake mechanism by Fe3O4 nanoparticles: towards new prospective theranostic SPIONs

    Science.gov (United States)

    Mokhodoeva, Olga; Vlk, Martin; Málková, Eva; Kukleva, Ekaterina; Mičolová, Petra; Štamberg, Karel; Šlouf, Miroslav; Dzhenloda, Rustam; Kozempel, Ján

    2016-10-01

    The use of superparamagnetic iron oxide nanoparticles ( SPIONs) and radiolabelled nanoparticles ( NPs) has grown considerably over the recent years, and the SPIONs labelled with medicinal radionuclides offer new opportunities in multimodal diagnostics and in the drug-delivery systems for targeted alpha-particle therapy (TAT) driven by magnetic field gradient or by biologically active moieties bound on NPs shell. However, the mechanisms of NPs radiolabelling are not studied substantially and still remain unclear, even though the way of label attachment directly implies the stability of the label-nanoparticle construct. Since the 223Ra was the first clinically approved alpha-emitter, it is a promising nuclide for further development of its targeted carriers. We report here on the study of 223Ra uptake by the Fe3O4 SPIONs, together with an attempt to propose the 223Ra uptake mechanism by the Fe3O4 NPs in the presence of a phosphate buffer a typical formulation medium, under the pseudo-equilibrium conditions. Further, the in vitro stability tests of the prepared [223Ra]Fe3O4 NPs were performed to estimate the 223Ra label stability. The potential use of 223Ra-labelled SPIONs in theranostic applications is also discussed.

  13. Atypical Dopamine Uptake Inhibitors that Provide Clues About Cocaine's Mechanism at the Dopamine Transporter

    Science.gov (United States)

    Hauck Newman, Amy; Katz, Jonathan L.

    The dopamine transporter (DAT) has been a primary target for cocaine abuse/addiction medication discovery. However predicted addiction liability and limited clinical evaluation has provided a formidable challenge for development of these agents for human use. The unique and atypical pharmacological profile of the benztropine (BZT) class of dopamine uptake inhibitors, in preclinical models of cocaine effects and abuse, has encouraged further development of these agents. Moreover, in vivo studies have challenged the original DAT hypothesis and demonstrated that DAT occupancy and subsequent increases in dopamine produced by BZT analogues are significantly delayed and long lasting, as compared to cocaine. These important and distinctive elements are critical to the lack of abuse liability among BZT analogues, and improve their potential for development as treatments for cocaine abuse and possibly other neuropsychiatric disorders.

  14. Structure of the atypical bacteriocin pectocin M2 implies a novel mechanism of protein uptake.

    Science.gov (United States)

    Grinter, Rhys; Josts, Inokentijs; Zeth, Kornelius; Roszak, Aleksander W; McCaughey, Laura C; Cogdell, Richard J; Milner, Joel J; Kelly, Sharon M; Byron, Olwyn; Walker, Daniel

    2014-07-01

    The colicin-like bacteriocins are potent protein antibiotics that have evolved to efficiently cross the outer membrane of Gram-negative bacteria by parasitizing nutrient uptake systems. We have structurally characterized the colicin M-like bacteriocin, pectocin M2, which is active against strains of Pectobacterium spp. This unusual bacteriocin lacks the intrinsically unstructured translocation domain that usually mediates translocation of these bacteriocins across the outer membrane, containing only a single globular ferredoxin domain connected to its cytotoxic domain by a flexible α-helix, which allows it to adopt two distinct conformations in solution. The ferredoxin domain of pectocin M2 is homologous to plant ferredoxins and allows pectocin M2 to parasitize a system utilized by Pectobacterium to obtain iron during infection of plants. Furthermore, we identify a novel ferredoxin-containing bacteriocin pectocin P, which possesses a cytotoxic domain homologous to lysozyme, illustrating that the ferredoxin domain acts as a generic delivery module for cytotoxic domains in Pectobacterium.

  15. Ferredoxin containing bacteriocins suggest a novel mechanism of iron uptake in Pectobacterium spp.

    Science.gov (United States)

    Grinter, Rhys; Milner, Joel; Walker, Daniel

    2012-01-01

    In order to kill competing strains of the same or closely related bacterial species, many bacteria produce potent narrow-spectrum protein antibiotics known as bacteriocins. Two sequenced strains of the phytopathogenic bacterium Pectobacterium carotovorum carry genes encoding putative bacteriocins which have seemingly evolved through a recombination event to encode proteins containing an N-terminal domain with extensive similarity to a [2Fe-2S] plant ferredoxin and a C-terminal colicin M-like catalytic domain. In this work, we show that these genes encode active bacteriocins, pectocin M1 and M2, which target strains of Pectobacterium carotovorum and Pectobacterium atrosepticum with increased potency under iron limiting conditions. The activity of pectocin M1 and M2 can be inhibited by the addition of spinach ferredoxin, indicating that the ferredoxin domain of these proteins acts as a receptor binding domain. This effect is not observed with the mammalian ferredoxin protein adrenodoxin, indicating that Pectobacterium spp. carries a specific receptor for plant ferredoxins and that these plant pathogens may acquire iron from the host through the uptake of ferredoxin. In further support of this hypothesis we show that the growth of strains of Pectobacterium carotovorum and atrosepticum that are not sensitive to the cytotoxic effects of pectocin M1 is enhanced in the presence of pectocin M1 and M2 under iron limiting conditions. A similar growth enhancement under iron limiting conditions is observed with spinach ferrodoxin, but not with adrenodoxin. Our data indicate that pectocin M1 and M2 have evolved to parasitise an existing iron uptake pathway by using a ferredoxin-containing receptor binding domain as a Trojan horse to gain entry into susceptible cells.

  16. Ferredoxin containing bacteriocins suggest a novel mechanism of iron uptake in Pectobacterium spp.

    Directory of Open Access Journals (Sweden)

    Rhys Grinter

    Full Text Available In order to kill competing strains of the same or closely related bacterial species, many bacteria produce potent narrow-spectrum protein antibiotics known as bacteriocins. Two sequenced strains of the phytopathogenic bacterium Pectobacterium carotovorum carry genes encoding putative bacteriocins which have seemingly evolved through a recombination event to encode proteins containing an N-terminal domain with extensive similarity to a [2Fe-2S] plant ferredoxin and a C-terminal colicin M-like catalytic domain. In this work, we show that these genes encode active bacteriocins, pectocin M1 and M2, which target strains of Pectobacterium carotovorum and Pectobacterium atrosepticum with increased potency under iron limiting conditions. The activity of pectocin M1 and M2 can be inhibited by the addition of spinach ferredoxin, indicating that the ferredoxin domain of these proteins acts as a receptor binding domain. This effect is not observed with the mammalian ferredoxin protein adrenodoxin, indicating that Pectobacterium spp. carries a specific receptor for plant ferredoxins and that these plant pathogens may acquire iron from the host through the uptake of ferredoxin. In further support of this hypothesis we show that the growth of strains of Pectobacterium carotovorum and atrosepticum that are not sensitive to the cytotoxic effects of pectocin M1 is enhanced in the presence of pectocin M1 and M2 under iron limiting conditions. A similar growth enhancement under iron limiting conditions is observed with spinach ferrodoxin, but not with adrenodoxin. Our data indicate that pectocin M1 and M2 have evolved to parasitise an existing iron uptake pathway by using a ferredoxin-containing receptor binding domain as a Trojan horse to gain entry into susceptible cells.

  17. Statistical Mechanics Approximation of Biogeography-Based Optimization.

    Science.gov (United States)

    Ma, Haiping; Simon, Dan; Fei, Minrui

    2016-01-01

    Biogeography-based optimization (BBO) is an evolutionary algorithm inspired by biogeography, which is the study of the migration of species between habitats. This paper derives a mathematical description of the dynamics of BBO based on ideas from statistical mechanics. Rather than trying to exactly predict the evolution of the population, statistical mechanics methods describe the evolution of statistical properties of the population fitness. This paper uses the one-max problem, which has only one optimum and whose fitness function is the number of 1s in a binary string, to derive equations that predict the statistical properties of BBO each generation in terms of those of the previous generation. These equations reveal the effect of migration and mutation on the population fitness dynamics of BBO. The results obtained in this paper are similar to those for the simple genetic algorithm with selection and mutation. The paper also derives equations for the population fitness dynamics of general separable functions, and we find that the results obtained for separable functions are the same as those for the one-max problem. The statistical mechanics theory of BBO is shown to be in good agreement with simulation.

  18. Geometric Mechanics Reveals Optimal Complex Terrestrial Undulation Patterns

    Science.gov (United States)

    Gong, Chaohui; Astley, Henry; Schiebel, Perrin; Dai, Jin; Travers, Matthew; Goldman, Daniel; Choset, Howie; CMU Team; GT Team

    Geometric mechanics offers useful tools for intuitively analyzing biological and robotic locomotion. However, utility of these tools were previously restricted to systems that have only two internal degrees of freedom and in uniform media. We show kinematics of complex locomotors that make intermittent contacts with substrates can be approximated as a linear combination of two shape bases, and can be represented using two variables. Therefore, the tools of geometric mechanics can be used to analyze motions of locomotors with many degrees of freedom. To demonstrate the proposed technique, we present studies on two different types of snake gaits which utilize combinations of waves in the horizontal and vertical planes: sidewinding (in the sidewinder rattlesnake C. cerastes) and lateral undulation (in the desert specialist snake C. occipitalis). C. cerastes moves by generating posteriorly traveling body waves in the horizontal and vertical directions, with a relative phase offset equal to +/-π/2 while C. occipitalismaintains a π/2 offset of a frequency doubled vertical wave. Geometric analysis reveals these coordination patterns enable optimal movement in the two different styles of undulatory terrestrial locomotion. More broadly, these examples demonstrate the utility of geometric mechanics in analyzing realistic biological and robotic locomotion.

  19. Topology optimum design of compliant mechanisms using modified ant colony optimization

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Kwang Seon; Han, Seog Young [Hanyang University, Seoul (Korea, Republic of)

    2015-08-15

    A Modified ant colony optimization (MACO) algorithm was suggested for topology optimal design of compliant mechanisms since standard ACO cannot provide an appropriate optimal topology. In order to improve computational efficiency and suitability of standard ACO algorithm in topology optimization for compliant mechanisms, a continuous variable, called the 'Element contribution significance (ECS),'is employed, which serves to replace the positions of ants in the standard ACO algorithm, and assess the importance of each element in the optimization process. MACO algorithm was applied to topology optimizations of both linear and geometrically nonlinear compliant mechanisms using three kinds of objective functions, and optimized topologies were compared each other. From the comparisons, it was concluded that MACO algorithm can effectively be applied to topology optimizations of linear and geometrically nonlinear compliant mechanisms, and the ratio of Mutual potential energy (MPE) to Strain energy (SE) type of objective function is the best for topology optimal design of compliant mechanisms.

  20. Optimization geological sequestration of CO2 by capillary trapping mechanisms

    Science.gov (United States)

    Wildenschild, D.; Harper, E.; Herring, A. L.; Armstrong, R. T.

    2012-12-01

    Geological carbon sequestration, as a method of atmospheric greenhouse gas reduction, is at the technological forefront of the climate change movement. Sequestration is achieved by capturing carbon dioxide (CO2) gas effluent from coal fired power plants and injecting it into saline aquifers. In an effort to fully understand and optimize CO2 trapping efficiency, the capillary trapping mechanisms that immobilize subsurface CO2 were analyzed at the pore scale. Pairs of analogous fluids representing the range of in situ supercritical CO2 and brine conditions were used during experimentation. The two fluids (identified as wetting and non wetting) were imbibed and drained from a flow cell apparatus containing a sintered glass bead column. Experimental and fluid parameters, such as interfacial tension, non-wetting fluid viscosity, and flow rate, were altered to characterize their impact on capillary trapping. Through the use of computed x-ray microtomography (CMT), we were able to quantify distinct differences between initial (post NW phase imbibition) and residual (post wetting fluid flood) non-wetting phase saturations. Alterations to the viscosity of the non-wetting and wetting fluid phases were made during experimentation; results indicate that the viscosity of the non-wetting fluid is the parameter of interest as residual saturations increased with increasing viscosity. These observed trends will be used to identify optimal conditions for trapping CO2 during subsurface sequestration.

  1. Isogeometric Analysis and Shape Optimization in Fluid Mechanics

    DEFF Research Database (Denmark)

    Nielsen, Peter Nørtoft

    unites the power to solve complex engineering problems from finite element analysis (FEA) with the ability to effectively represent complex shapes from computer aided design (CAD). The methodology is appealing for flow modeling purposes also due to the inherent high regularity of velocity and pressure......This thesis brings together the fields of fluid mechanics, as the study of fluids and flows, isogeometric analysis, as a numerical method to solve engineering problems using computers, and shape optimization, as the art of finding "best" shapes of objects based on some notion of goodness. The flow...... is given of how isogeometric analysis is applied to flow problems. We present several new discretizations of the velocity and pressure spaces, we investigate these in terms of stability and error convergence properties, and a benchmark flow problem is analyzed. As the second contribution, we show how...

  2. Mechanical design optimization of bioabsorbable fixation devices for bone fractures.

    Science.gov (United States)

    Lovald, Scott T; Khraishi, Tariq; Wagner, Jon; Baack, Bret

    2009-03-01

    Bioabsorbable bone plates can eliminate the necessity for a permanent implant when used to fixate fractures of the human mandible. They are currently not in widespread use because of the low strength of the materials and the requisite large volume of the resulting bone plate. The aim of the current study was to discover a minimally invasive bioabsorbable bone plate design that can provide the same mechanical stability as a standard titanium bone plate. A finite element model of a mandible with a fracture in the body region is subjected to bite loads that are common to patients postsurgery. The model is used first to determine benchmark stress and strain values for a titanium plate. These values are then set as the limits within which the bioabsorbable bone plate must comply. The model is then modified to consider a bone plate made of the polymer poly-L/DL-lactide 70/30. An optimization routine is run to determine the smallest volume of bioabsorbable bone plate that can perform and a titanium bone plate when fixating fractures of this considered type. Two design parameters are varied for the bone plate design during the optimization analysis. The analysis determined that a strut style poly-L-lactide-co-DL-lactide plate of 690 mm2 can provide as much mechanical stability as a similar titanium design structure of 172 mm2. The model has determined a bioabsorbable bone plate design that is as strong as a titanium plate when fixating fractures of the load-bearing mandible. This is an intriguing outcome, considering that the polymer material has only 6% of the stiffness of titanium.

  3. Determination of rate constants for the uptake process involving SO{sub 2} and an aerosol particle. A quantum mechanics/molecular mechanics and quantum statistical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Marianne Sloth [Department of Chemistry, H.C. Orsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Danish Meteorological Institute, Lyngbyvej 100, DK-2100 Copenhagen O (Denmark)], E-mail: msm@dmi.dk; Gross, Allan [Department of Chemistry, H.C. Orsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Danish Meteorological Institute, Lyngbyvej 100, DK-2100 Copenhagen O (Denmark); Falsig, Hanne [Department of Chemistry, H.C. Orsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Kongsted, Jacob [Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124, S-22100 Lund (Sweden); Osted, Anders; Mikkelsen, Kurt V. [Department of Chemistry, H.C. Orsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen O (Denmark); Christiansen, Ove [Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus C (Denmark)

    2008-06-02

    We present a combined quantum mechanics/molecular mechanics and quantum statistical investigation of the interactions between a molecule (SO{sub 2}) and an aerosol particle including rate constants for the uptake process. A coupled cluster/molecular mechanics method including explicit polarization is used along with a quantum statistical method for calculating sticking coefficients. The importance of the polarization of the classical subsystem (the aerosol particle), the size of the classical subsystem and the size of one-electron basis sets are studied. The interaction energy is divided into van der Waals, electrostatic and polarization contributions. Relevant binding sites for the evaluation of the sticking coefficient are identified. These are classified into three groups according to the strength of the molecule-aerosol particle interaction energy. The identification of binding sites provides relevant information used in the quantum statistical method and thereby knowledge of the magnitude of the sticking coefficients for the different binding sites along with the total rates for the uptake processes between the aerosol particle and the SO{sub 2} molecule.

  4. Toxicological effects of multi-walled carbon nanotubes on Saccharomyces cerevisiae: The uptake kinetics and mechanisms and the toxic responses

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Song; Zhu, Bin; Huang, Aiguo [College of Animal Science and Technology, Northwest A& F University, Yangling 712100 (China); Hu, Yang [College of Science, Northwest A& F University, Yangling 712100 (China); Wang, Gaoxue, E-mail: wanggaoxue@126.com [College of Animal Science and Technology, Northwest A& F University, Yangling 712100 (China); Ling, Fei, E-mail: feiling@nwsuaf.edu.cn [College of Animal Science and Technology, Northwest A& F University, Yangling 712100 (China)

    2016-11-15

    Highlights: • MWCNTs (<100 mg/L) were not toxic to S. cerevisiae. • MWCNTs were internalized in S. cerevisiae cells by three pathways. • The uptake kinetics and the subcellular distribution of MWCNTs in S. cerevisiae cells were shown. • S. cerevisiae cells were undergoing apoptosis by mitochondrial impairment pathway. - Abstract: Using Saccharomyces cerevisiae as an experimental model, the potential toxicological effects of oxidized multi-walled carbon nanotubes (MWCNTs) were investigated following exposure to 0–600 mg/L for 24 h. Results indicated that MWCNTs (>100 mg/L) had adverse effects on the cell proliferation. MWCNTs were clearly visible in lysosome, vacuole, endosome, mitochondria, multivesicular body and localization in the perinuclear region. The uptake kinetics data demonstrated that the maximum MWCNTs content (209.61 mg/g) was reached at 3 h, and a steady state was reached after 18 h. Based on the combined results of transmission electron microscope, endocytosis inhibition experiments and endocytosis-related genes (END3, END6, Sla2 and Rsp5) expression analysis, we elucidated MWCNTs uptake mechanism: (i) via a direct penetration of single MWCNTs; (ii) via endocytosis of single MWCNTs; and (iii) via endocytosis of MWCNTs aggregates. The percentage of apoptosis was significant increased at 600 mg/L. The decrease of mitochondrial transmembrane potential and the leakage of cytochrome c shown dose-dependent manners. Interestingly, there was no significant increase of reactive oxygen species (ROS). The apoptosis-related genes (SOD1, SOD2, Yca1, Nma111 and Nuc1) were significant changed. These results obtained in our study demonstrated that oxidized MWCNTs induce Saccharomyces cerevisiae apoptosis via mitochondrial impairment pathway.

  5. Optimal mechanical harvester route planning for sugarcane f ield operations using particle swarm optimization

    Directory of Open Access Journals (Sweden)

    Woraya Neungmatcha

    2015-06-01

    Full Text Available Since current agricultural production systems such as the sugarcane supply system in the sugar industry are developing towards larger and more complicated systems, there is consequently increasing use of agricultural machinery. Even though mechanization can help to increase the sugarcane yield, if the mechanical operation efficiency is low, then higher harvest costs and machinery shortages will occur. Global route planning for mechanical harvesters is one of the most important problems in the field of sugarcane harvesting and transporting operations. Improved efficiency and realistic implementation can be achieved by applying advanced planning methods for the execution of field operations, especially considering the field accessibility aspect. To address this issue, participative research was undertaken with a sugar milling company to produce and implement a mixed integer programming model that represents the mechanical harvester route plan. Particle swarm optimization was applied to find a solution to the model, leading to potential cost savings versus schedules produced manually by the mill officer. The model was also applied to explore regional planning options for a more integrated harvesting and transport system.

  6. Water uptake mechanism and germination of Erythrina velutina seeds treated with atmospheric plasma

    Science.gov (United States)

    Alves Junior, Clodomiro; de Oliveira Vitoriano, Jussier; da Silva, Dinnara Layza Souza; de Lima Farias, Mikelly; de Lima Dantas, Nadjamara Bandeira

    2016-09-01

    The effect of plasma applied to mulungu (Erythrina velutina) seeds was studied to verify its influence on the germination, water absorption, wettability and structure of the seeds. The plasma jet used in this study was produced by dielectric barrier discharge (DBD) in a helium gas flow of 0.03 L/s at a distance of 13 mm for 60 s. The plasma treatment significantly affected the seed germination rate, which was approximately 5% higher than that of the untreated group. Micropyle and hilum contributed a greater proportion to uptake. When sealed in the hilar or micropyle regions the amount of water absorbed into the seed decreased approximately 75% compared to the unsealed seed. This difference suggests that these two regions together act cooperatively in the water absorption. However, when plasma treated seed was blocked in the micropyle region, water absorption was higher higher than in seeds blocked hilum. This difference suggests that the plasma treatment changed the wettability of the hilum more effectively than it changed the micropyle. These results indicate that plasma can significantly change the hydrophilicity, water absorption and percentage of seed germination in E. velutina.

  7. Water uptake mechanism and germination of Erythrina velutina seeds treated with atmospheric plasma

    Science.gov (United States)

    Alves Junior, Clodomiro; de Oliveira Vitoriano, Jussier; da Silva, Dinnara Layza Souza; de Lima Farias, Mikelly; de Lima Dantas, Nadjamara Bandeira

    2016-01-01

    The effect of plasma applied to mulungu (Erythrina velutina) seeds was studied to verify its influence on the germination, water absorption, wettability and structure of the seeds. The plasma jet used in this study was produced by dielectric barrier discharge (DBD) in a helium gas flow of 0.03 L/s at a distance of 13 mm for 60 s. The plasma treatment significantly affected the seed germination rate, which was approximately 5% higher than that of the untreated group. Micropyle and hilum contributed a greater proportion to uptake. When sealed in the hilar or micropyle regions the amount of water absorbed into the seed decreased approximately 75% compared to the unsealed seed. This difference suggests that these two regions together act cooperatively in the water absorption. However, when plasma treated seed was blocked in the micropyle region, water absorption was higher higher than in seeds blocked hilum. This difference suggests that the plasma treatment changed the wettability of the hilum more effectively than it changed the micropyle. These results indicate that plasma can significantly change the hydrophilicity, water absorption and percentage of seed germination in E. velutina. PMID:27670654

  8. Resonant optimization in the mechanical unzipping of DNA

    Science.gov (United States)

    Bergues-Pupo, Ana Elisa; Falo, Fernando; Fiasconaro, Alessandro

    2014-03-01

    The mechanical separation of the double-stranded DNA in single-molecule experiments is of fundamental importance in the understanding of the replication or transcription processes. Time-dependent forces can influence in different ways the dynamics of this separation. We study here this unzipping of DNA in the framework of the mesoscopic Peyrard-Bishop-Dauxois model under the influence of a periodic driving. Two different protocols, both of them feasible experimentally, have been studied under two modes of pulling: controlled force and controlled position. A strong resonant activation phenomenon has been observed in the magnitudes that characterize the mechanical unzipping such as the mean opening time, the mean opening force, and the mean critical opening force, all of them as a function of the frequency of the driving. This optimal frequency region has been observed for all the cases studied both in a uniform DNA of adenine-thymine nucleotides and in a real DNA sequence. Importantly, a well precise resonant frequency can be determined with the use of one of this protocols.

  9. Lipid-modified oligonucleotide conjugates: Insights into gene silencing, interaction with model membranes and cellular uptake mechanisms.

    Science.gov (United States)

    Ugarte-Uribe, Begoña; Grijalvo, Santiago; Pertíñez, Samuel Núñez; Busto, Jon V; Martín, César; Alagia, Adele; Goñi, Félix M; Eritja, Ramón; Alkorta, Itziar

    2017-01-01

    The ability of oligonucleotides to silence specific genes or inhibit the biological activity of specific proteins has generated great interest in their use as research tools and therapeutic agents. Unfortunately, their biological applications meet the limitation of their poor cellular accessibility. Developing an appropriate delivery system for oligonucleotides is essential to achieve their efficient cellular uptake. In the present work a series of phosphorothioate lipid-oligonucleotide hybrids were synthesized introducing covalently single or double lipid tails at both 3'- and 5'-termini of an antisense oligonucleotide. Gene transfections in cultured cells showed antisense luciferase inhibition without the use of a transfecting agent for conjugates modified with the double-lipid tail at 5'-termini. The effect of the double lipid-tailed modification was further studied in detail in several model membrane systems as well as in cellular uptake experiments. During these studies the spontaneous formation of self-assembled microstructures is clearly observed. Lipidation allowed the efficient incorporation of the oligonucleotide in HeLa cells by a macropinocytosis mechanism without causing cytotoxicity in cells or altering the binding properties of the oligonucleotide conjugates. In addition, both single- and double-tailed compounds showed a similar behavior in lipid model membranes, making them useful in nucleotide-based technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Uptake mechanism of furosemide-loaded pegylated nanoparticles by cochlear cell lines.

    Science.gov (United States)

    Youm, Ibrahima; Youan, Bi-Botti C

    2013-10-01

    This study tests the hypothesis that pegylated nanoparticles (NPs) could be taken up by the cochlear cells [House Ear Institute-organ of Corti 1 (HEI-OC1) and Stria vascularis K-1 (SVK-1)], through endocytic pathways. Furthermore, the in vitro drug release and the cytotoxicity of Furosemide (FUR)-loaded NPs on these two cochlear cells are investigated. FUR-loaded pegylated NPs are prepared by the emulsion-solvent diffusion method without surfactant. The NPs are characterized for particle mean diameter, polydispersity index (PDI), morphology, percent drug encapsulation efficiency (EE%), and FUR release kinetics. The methyl tetrazolium salt (MTS) and lactate dehydrogenase (LDH) bioassays are used to evaluate in vitro, the cytotoxicity of FUR-loaded NPs and native FUR. The NPs uptake is investigated using confocal microscopy, microplate reader/fluorimetry, and flow cytometry. Spherical NPs with a mean diameter range of 133-210 nm and PDI values varying from 0.037 to 0.41 are produced. The FUR EE% is 86% and the drug is released from the NPs according to the zero-order and Higuchi models. After treatment with blank NPs, the percentage of cell viability and cell death are 95.96% and 8.95%, in HEI-OC1 cells, respectively. The NPs are internalized by HEI-OC1 cells through a clathrin-dependent pathway. In addition, results show that NPs can be taken up via clathrin and cytoskeleton mediated pathways in SVK-1 cells. The internalization of the pegylated NPs can enhance the drug toxicity by necrosis in a dose-dependent and sustained release manner. The formulated NPs provide a promising template for a targeted drug delivery system to the inner ear.

  11. Remarkable Improvement in the Mechanical Properties and CO2 Uptake of MOFs Brought About by Covalent Linking to Graphene.

    Science.gov (United States)

    Kumar, Ram; Raut, Devaraj; Ramamurty, Upadrasta; Rao, C N R

    2016-06-27

    Metal-organic frameworks (MOFs) are exceptional as gas adsorbents but their mechanical properties are poor. We present a successful strategy to improve the mechanical properties along with gas adsorption characteristics, wherein graphene (Gr) is covalently bonded with M/DOBDC (M=Mg(2+) , Ni(2+) , or Co(2+) , DOBDC=2,5-dioxido-1,4-benzene dicarboxylate) MOFs. The surface area of the graphene-MOF composites increases up to 200-300 m(2)  g(-1) whereas the CO2 uptake increases by ca. 3-5 wt % at 0.15 atm and by 6-10 wt % at 1 atm. What is significant is that the composites exhibit improved mechanical properties. In the case of Mg/DOBDC, a three-fold increase in both the elastic modulus and hardness with 5 wt % graphene reinforcement is observed. Improvement in both the mechanical properties and gas adsorption characteristics of porous MOFs on linking them to graphene is a novel observation and suggests a new avenue for the design and synthesis of porous materials.

  12. Initial heme uptake from albumin by short-term cultured rat hepatocytes is mediated by a transport mechanism differing from that of other organic anions.

    Science.gov (United States)

    Noyer, C M; Immenschuh, S; Liem, H H; Muller-Eberhard, U; Wolkoff, A W

    1998-07-01

    Although it is known that circulating heme accumulates in liver cells, the process by which heme enters hepatocytes is only partly understood. Hemopexin and a putative hemopexin receptor on hepatocyte membranes may mediate the uptake process. However, whether there are sufficient hemopexin receptors on rat hepatocytes to account for the bulk of heme entering cells is unknown. It is likely that heme may be transferred directly from albumin with the help of a plasma membrane heme transporter. To clarify the transport mechanism of heme into liver cells, we studied the uptake by short-term cultured rat hepatocytes of 55Fe-heme incubated with rat serum albumin. In these cells, the initial uptake of 55Fe-heme at 37 degrees C was five- to eightfold higher than that at 4 degrees C, linear for at least 5 minutes, and saturable. The Km of heme uptake was 0.95 +/- 0.27 micromol/L, and the Vmax was 0.12 +/- 0.01 pmol/min/mg protein (n = 3). Neither isosmotic substitution of sucrose for NaCl in the medium nor adenosine triphosphate (ATP) depletion, perturbations that are known to reduce uptake of bilirubin, sulfobromophthalein (BSP), and taurocholate, had any influence on 55Fe-heme uptake. In addition, heme uptake was not reduced in the presence of a greater than 500-fold molar excess of BSP. These results indicate that hepatocytes take up heme by a process that is distinct from that of these other organic anions.

  13. The Yin: An adverse health perspective of nanoceria: uptake, distribution, accumulation, and mechanisms of its toxicity.

    Science.gov (United States)

    Yokel, Robert A; Hussain, Salik; Garantziotis, Stavros; Demokritou, Philip; Castranova, Vincent; Cassee, Flemming R

    2014-10-01

    This critical review evolved from a SNO Special Workshop on Nanoceria panel presentation addressing the toxicological risks of nanoceria: accumulation, target organs, and issues of clearance; how exposure dose/concentration, exposure route, and experimental preparation/model influence the different reported effects of nanoceria; and how can safer by design concepts be applied to nanoceria? It focuses on the most relevant routes of human nanoceria exposure and uptake, disposition, persistence, and resultant adverse effects. The pulmonary, oral, dermal, and topical ocular exposure routes are addressed as well as the intravenous route, as the latter provides a reference for the pharmacokinetic fate of nanoceria once introduced into blood. Nanoceria reaching the blood is primarily distributed to mononuclear phagocytic system organs. Available data suggest nanoceria's distribution is not greatly affected by dose, shape, or dosing schedule. Significant attention has been paid to the inhalation exposure route. Nanoceria distribution from the lung to the rest of the body is less than 1% of the deposited dose, and from the gastrointestinal tract even less. Intracellular nanoceria and organ burdens persist for at least months, suggesting very slow clearance rates. The acute toxicity of nanoceria is very low. However, large/accumulated doses produce granuloma in the lung and liver, and fibrosis in the lung. Toxicity, including genotoxicity, increases with exposure time; the effects disappear slowly, possibly due to nanoceria's biopersistence. Nanoceria may exert toxicity through oxidative stress. Adverse effects seen at sites distal to exposure may be due to nanoceria translocation or released biomolecules. An example is elevated oxidative stress indicators in the brain, in the absence of appreciable brain nanoceria. Nanoceria may change its nature in biological environments and cause changes in biological molecules. Increased toxicity has been related to greater surface Ce(3

  14. Optimal Structural Design of Complicated Mechanical Products Based on Data Mining

    Institute of Scientific and Technical Information of China (English)

    TAO Jing; WU Qing-ming; SUN Chuan

    2009-01-01

    Complicated mechanical products normally consist of multi-parameter mechanisms. The couplings between two tmechanisms are either strong or weak. The traditional optimal design methods cannot meet the requirements of optimal structural design of the complicated multi-parameter mechanical products. On the basis of analyzing the optimal design methods and the data mining principles, an improved iterative dichotomizer 3 (ID3) algorithm is hereby put forth to bring out an optimal design information model integrated with the data mining technology as well as an optimal structural design system of complicated mechanical products based on the data mining principles. The system is demonstrated by the optimal structural design of the mainframe of the full face rock tunnel boring machine (TBM). An example shows that the data mining technology has fully tackled the issues of the optimal structural design of complicated mechanical products.

  15. A new paradigm for aptamer therapeutic AS1411 action: uptake by macropinocytosis and its stimulation by a nucleolin-dependent mechanism.

    Science.gov (United States)

    Reyes-Reyes, E Merit; Teng, Yun; Bates, Paula J

    2010-11-01

    AS1411 is a first-in-class anticancer agent, currently in phase II clinical trials. It is a quadruplex-forming oligodeoxynucleotide that binds to nucleolin as an aptamer, but its mechanism of action is not completely understood. Mechanistic insights could lead to clinically useful markers for AS1411 response and to novel targeted therapies. Previously, we proposed a model where cell surface nucleolin serves as the receptor for AS1411, leading to selective uptake in cancer cells. Here, we compare uptake of fluorophore-labeled AS1411 (FL-AS1411) in DU145 prostate cancer cells (sensitive to AS1411) and Hs27 nonmalignant skin fibroblasts (resistant to AS1411). Uptake of FL-AS1411 occurred by endocytosis in both cell types and was much more efficient than an inactive, nonquadruplex oligonucleotide. Unexpectedly, uptake of FL-AS1411 was lower in cancer cells compared with Hs27 cells. However, the mechanism of uptake was different, occurring by macropinocytosis in cancer cells, but by a nonmacropinocytic pathway in Hs27 cells. Additionally, treatment of various cancer cells with AS1411 caused hyperstimulation of macropinocytosis, provoking an increase in its own uptake, whereas no stimulation was observed for nonmalignant cells. Nucleolin was not required for initial FL-AS1411 uptake in DU145 cells but was necessary for induced macropinocytosis and FL-AS1411 uptake at later times. Our results are inconsistent with the previous mechanistic model but confirm that nucleolin plays a role in mediating AS1411 effects. The data suggest a new model for AS1411 action as well as a new role for nucleolin in stimulating macropinocytosis, a process with potential applications in drug delivery.

  16. Temporal evolution of mechanisms controlling ocean carbon uptake during the last glacial cycle

    Science.gov (United States)

    Kohfeld, Karen E.; Chase, Zanna

    2017-08-01

    Many mechanisms have been proposed to explain the ∼85-90 ppm decrease in atmospheric carbon dioxide (CO2) during the last glacial cycle, between 127,000 and 18,000 yrs ago. When taken together, these mechanisms can, in some models, account for the full glacial-interglacial CO2 drawdown. Most proxy-based evaluations focus on the peak of the Last Glacial Maximum, 24,000-18,000 yrs ago, and little has been done to determine the sequential timing of processes affecting CO2 during the last glacial cycle. Here we use a new compilation of sea-surface temperature records together with time-sequenced records of carbon and Nd isotopes, and other proxies to determine when the most commonly proposed mechanisms could have been important for CO2 drawdown. We find that the initial major drawdown of 35 ppm 115,000 yrs ago was most likely a result of Antarctic sea ice expansion. Importantly, changes in deep ocean circulation and mixing did not play a major role until at least 30,000 yrs after the first CO2 drawdown. The second phase of CO2 drawdown occurred ∼70,000 yrs ago and was also coincident with the first significant influences of enhanced ocean productivity due to dust. Finally, minimum concentrations of atmospheric CO2 during the Last Glacial Maximum resulted from the combination of physical and biological factors, including the barrier effect of expanded Southern Ocean sea ice, slower ventilation of the deep sea, and ocean biological feedbacks.

  17. A Framework for Multidisciplinary Optimization of a Balancing Mechanism for an Industrial Robot

    Directory of Open Access Journals (Sweden)

    Johan A. Persson

    2015-01-01

    Full Text Available The paper presents a framework that can be used to design and optimize a balancing mechanism for an industrial robot. The framework has the capability to optimize three different concepts: a mechanical, a pneumatic, and a hydropneumatic. Several disciplines are included in the framework, such as dynamic and static analyses of the robot performance. Optimization is performed for each concept and the obtained optimal designs are all better than the reference design. This means that the framework can be used as a tool both to optimize the balancing mechanism and also to support concept selection.

  18. Optimization of Kinematics of a Flapping Wing Mechanism

    Science.gov (United States)

    George, Ryan; Thomson, Scott; Mattson, Christopher; Colton, Mark; Tree, Mike

    2010-11-01

    Flapping flight offers several potential advantages over conventional fixed wing flight, such as agility and maneuverability in confined spaces, potentially decreased noise and detectability, and hovering capability. In this presentation, a water tunnel-based flapping wing apparatus is introduced that allows for arbitrary wing trajectories in three rotational degrees of freedom and simultaneous measurements of lift and thrust production. An optimal flapping trajectory for takeoff is found using hardware-in-the-loop optimization methodology. Wing motion derived from high-speed imaging of a ladybug during takeoff is used as a first iteration of the hardware-in-the-loop optimization. Using real-time force measurements and a gradient-based optimization approach, the algorithm searches for the optimal trajectory for a variety of parameters such as lift or efficiency. Hardware performance is assessed. Results from the optimization routine, including the final flapping trajectory are reported for both rigid and compliant wings.

  19. Mechanism of uranium(VI) uptake by Saccharomyces cerevisiae under environmentally relevant conditions: Batch, HRTEM, and FTIR studies

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xia, E-mail: lux2009@lzu.edu.cn; Zhou, Xiao-jiao; Wang, Tie-shan, E-mail: tswang@lzu.edu.cn

    2013-11-15

    Highlights: • Equilibrium reaches very rapid within 15 min. • pH shift towards neutral indicates release of hydroxyl ions. • High ionic strength inhabits biosorption capacity. • Uptake capacity of heat-killed cells is an order of magnitude higher than live one. • Electrostatic interaction, precipitation, and complexation are the main mechanisms. -- Abstract: Biosorption is of significance for the safety evaluation of high-level nuclear wastes repositories and remediation of radioactive contamination places. Quantitive study and structural characterization of uranium uptake by both live and heat-killed Saccharomyces cerevisiae at environmentally relevant uranium concentration and with different ionic strengths were carried out. Kinetic investigation showed the equilibrium reached within 15 min. In equilibrium studies, pH shift towards neutral indicated release of hydroxyl ions. pH was the most important factor, which partly affected electrostatic interaction between uranyl ions and S. cerevisiae surface. The high ionic strength inhibited biosorption capacity, which can be explained by a competitive reaction between sodium ions and uranyl ions. Heat killing process significantly enhanced biosorption capacity, showing an order of magnitude higher than that of live cells. High resolution transmission electron microscopy (HRTEM) coupled with energy dispersive X-ray (EDX) showed needle-like uranium-phosphate precipitation formed on the cell walls for both live and heat-killed cells. Besides, dark-field micrographs displayed considerable similar uranium-phosphate precipitation presented outside the heat-killed cells. The phosphate released during heat-killing process. FTIR illustrated function groups hydroxyl, carboxyl, phosphate, and amino groups played important role in complexation with uranium.

  20. Optimizing Size and Copy Number For PEG-fMLF (N-Formyl-methionyl-leucyl-phenylalanine) Nanocarrier Uptake by Macrophages

    Science.gov (United States)

    Wan, Li; Zhang, Xiaoping; Pooyan, Shahriar; Palombo, Matthew S.; Leibowitz, Michael J.; Stein, Stanley; Sinko, Patrick J.

    2009-01-01

    Curing HIV-1 infection has remained elusive because of low and fluctuating drug levels arising from poor absorption, the development of viral reservoirs and sanctuary sites, toxicity, and patient nonadherence. The present study addresses the issue of insufficient drug exposure in macrophages. Viral reservoir sites such as macrophages are believed to be responsible for the viral rebound effect observed upon the discontinuation of anti-HIV drug therapy. In our proposed model, a drug can be covalently attached to a nanocarrier in order to facilitate the delivery of therapeutic agents to the site(s) of infection. As an initial step, we propose the covalent attachment of several copies of N-formyl-Met-Leu-Phe (fMLF), a known chemo-attractant for macrophages. In this article, one or more copies of fMLF were conjugated to multifunctional commercially available or novel, peptide-based PEG nanocarriers in which the structure was varied by appending PEGs with average molecular weights of 5, 20, and 40 kDa. U937 cell-specific binding and cellular uptake were analyzed. The results of uptake studies indicate that (i) uptake is energy dependent and mediated by a fMLF receptor, (ii) appending only 2 copies of the targeting ligand to the multifunctional nanocarrier appears sufficient for binding in vitro, and (iii) of the three configurations studied, the nanocarrier with a molecular weight of about 20 kDa, corresponding to a size of 20−60 nm, demonstrated the highest uptake. The results of the current studies demonstrate the feasibility of targeting macrophages and the suitability of using these synthetically versatile peptide–backbone PEG nanocarriers. The convenience, flexibility and possible limitations of this nanocarrier approach are discussed. PMID:18092743

  1. Reliability-based design optimization for flexible mechanism with particle swarm optimization and advanced extremum response surface method

    Institute of Scientific and Technical Information of China (English)

    张春宜; 宋鲁凯; 费成巍; 郝广平; 刘令君

    2016-01-01

    To improve the computational efficiency of the reliability-based design optimization (RBDO) of flexible mechanism, particle swarm optimization-advanced extremum response surface method (PSO-AERSM) was proposed by integrating particle swarm optimization (PSO) algorithm and advanced extremum response surface method (AERSM). Firstly, the AERSM was developed and its mathematical model was established based on artificial neural network, and the PSO algorithm was investigated. And then the RBDO model of flexible mechanism was presented based on AERSM and PSO. Finally, regarding cross-sectional area as design variable, the reliability optimization of flexible mechanism was implemented subject to reliability degree and uncertainties based on the proposed approach. The optimization results show that the cross-section sizes obviously reduce by 22.96 mm2 while keeping reliability degree. Through the comparison of methods, it is demonstrated that the AERSM holds high computational efficiency while keeping computational precision for the RBDO of flexible mechanism, and PSO algorithm minimizes the response of the objective function. The efforts of this work provide a useful sight for the reliability optimization of flexible mechanism, and enrich and develop the reliability theory as well.

  2. Plant-driven removal of heavy metals from soil: uptake, translocation, tolerance mechanism, challenges, and future perspectives.

    Science.gov (United States)

    Thakur, Sveta; Singh, Lakhveer; Wahid, Zularisam Ab; Siddiqui, Muhammad Faisal; Atnaw, Samson Mekbib; Din, Mohd Fadhil Md

    2016-04-01

    Increasing heavy metal (HM) concentrations in the soil have become a significant problem in the modern industrialized world due to several anthropogenic activities. Heavy metals (HMs) are non-biodegradable and have long biological half lives; thus, once entered in food chain, their concentrations keep on increasing through biomagnification. The increased concentrations of heavy metals ultimately pose threat on human life also. The one captivating solution for this problem is to use green plants for HM removal from soil and render it harmless and reusable. Although this green technology called phytoremediation has many advantages over conventional methods of HM removal from soils, there are also many challenges that need to be addressed before making this technique practically feasible and useful on a large scale. In this review, we discuss the mechanisms of HM uptake, transport, and plant tolerance mechanisms to cope with increased HM concentrations. This review article also comprehensively discusses the advantages, major challenges, and future perspectives of phytoremediation of heavy metals from the soil.

  3. [Mechanism Study of the Smectite-OR-SH Compound for Reducing Cadmium Uptake by Plants in Contaminated Soils].

    Science.gov (United States)

    Zeng, Yan-jun; Zhou, Zhi-jun; Zhao, Qiu-xiang

    2015-06-01

    Adsorption and desorption experiments, pot experiments and characterization test were performed to investigate the immobilization effect and mechanism of the smectite-OR-SH compound for reducing cadmium uptake by plants in contaminated soils. The results showed that the saturated adsorption capacity for the adsorption of Cd2+ on smectite raised distinctly after functionalized. The adsorption of Cd2+ on smectite-OR-SH compound was very stable and it was difficult for Cd2+ to be desorbed from it. Crop yields promoted differently in original soil, Cd 3 mg x kg(-1) soil and Cd 10 mg x kg(-1) soil after adding the smectite-OR-SH compound. And the cadmium content of the cabbage reduced 61.00%, 62.10% and 83.73% respectively compare with the control. Characterization test analysis showed that Cd was adsorbed by the compound successfully and ligand interaction occurred between Cd and the thiol group. Floc amount on the compound surface increased correspondingly. In addition to electrostatic adsorption, ion exchange and hydroxyl ligand adsorption, the reaction mechanism of smectite-OR-SH compound with Cd was mainly sulfhydryl ligand adsorption.

  4. 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.

  5. Intracellular uptake: a possible mechanism for silver engineered nanoparticle toxicity to a freshwater alga Ochromonas danica.

    Directory of Open Access Journals (Sweden)

    Ai-Jun Miao

    Full Text Available The behavior and toxicity of silver engineered nanoparticles (Ag-ENs to the mixotrophic freshwater alga Ochromonas danica were examined in the present study to determine whether any other mechanisms are involved in their algal toxicity besides Ag(+ liberation outside the cells. Despite their good dispersability, the Ag-ENs were found to continuously aggregate and dissolve rapidly. When the initial nanoparticle concentration was lower than 10 µM, the total dissolved Ag(+ concentration ([Ag(+](T in the suspending media reached its maximum after 1 d and then decreased suggesting that Ag(+ release might be limited by the nanoparticle surface area under these conditions. Furthermore, Ag-EN dissolution extent remarkably increased in the presence of glutathione. In the Ag-EN toxicity experiment, glutathione was also used to eliminate the indirect effects of Ag(+ that was released. However, remarkable toxicity was still observed although the free Ag(+ concentration in the media was orders of magnitude lower than the non-observed effect concentration of Ag(+ itself. Such inhibitive effects were mitigated when more glutathione was added, but could never be completely eliminated. Most importantly, we demonstrate, for the first time, that Ag-ENs can be taken in and accumulated inside the algal cells, where they exerted their toxic effects. Therefore, nanoparticle internalization may be an alternative pathway through which algal growth can be influenced.

  6. A level set method for reliability-based topology optimization of compliant mechanisms

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the level set model and the reliability theory, a numerical approach of reliability-based topology optimization for compliant mechanisms with multiple inputs and outputs is presented. A multi-objective topology optimal model of compliant mechanisms considering uncertainties of the loads, material properties, and member geometries is developed. The reliability analysis and topology optimization are integrated in the optimal iterative process. The reliabilities of the compliant mechanisms are evaluated by using the first order reliability method. Meanwhile, the problem of structural topology optimization is solved by the level set method which is flexible in handling complex topological changes and concise in describing the boundary shape of the mechanism. Numerical examples show the importance of considering the stochastic nature of the compliant mechanisms in the topology optimization process.

  7. Structure-dependent effects of pyridine derivatives on mechanisms of intestinal fatty acid uptake: regulation of nicotinic acid receptor and fatty acid transporter expression.

    Science.gov (United States)

    Riedel, Annett; Lang, Roman; Rohm, Barbara; Rubach, Malte; Hofmann, Thomas; Somoza, Veronika

    2014-07-01

    Pyridines are widely distributed in foods. Nicotinic acid (NA), a carboxylated pyridine derivative, inhibits lipolysis in adipocytes by activation of the orphan NA receptor (HM74A) and is applied to treat hyperlipidemia. However, knowledge on the impact of pyridine derivatives on intestinal lipid metabolism is scarce. This study was performed to identify the structural determinants of pyridines for their effects on fatty acid uptake in enterocyte-like Caco-2 cells and to elucidate the mechanisms of action. The impact of 17 pyridine derivatives on fatty acid uptake was tested. Multiple regression analysis revealed the presence of a methyl group to be the structural determinant at 0.1 mM, whereas at 1 mM, the presence of a carboxylic group and the N-methylation presented further structural characteristics to affect the fatty acid uptake. NA, showing a stimulating effect on FA uptake, and N-methyl-4-phenylpyridinium (MPP), inhibiting FA uptake, were selected for mechanistic studies. Gene expression of the fatty acid transporters CD36, FATP2 and FATP4, and the lipid metabolism regulating transcription factors peroxisome proliferator-activated receptor (PPAR) α and PPARγ was up-regulated upon NA treatment. Caco-2 cells were demonstrated to express the low-affinity NA receptor HM74 of which the gene expression was up-regulated upon NA treatment. We hypothesize that the NA-induced fatty acid uptake might result from NA receptor activation and related intracellular signaling cascades. In contrast, MPP increased transepithelial electrical resistance. We therefore conclude that NA and MPP, both sharing the pyridine motif core, exhibit their contrary effects on intestinal FA uptake by activation of different mechanisms.

  8. Assessment and optimization of electroporation-assisted tumoral nanoparticle uptake in a nude mouse model of pancreatic ductal adenocarcinoma.

    Science.gov (United States)

    West, Derek Lamont; White, Sarah B; Zhang, Zhouli; Larson, Andrew C; Omary, Reed A

    2014-01-01

    Pancreatic ductal adenocarcinoma (PDAC) is a particularly lethal form of cancer. In 2012, the incidence of PDAC was 43,920. Five-year survival for patients with PDAC is around 6%, regardless of staging, making PDAC one of the deadliest forms of cancer. One reason for this dismal prognosis is chemoresistance to the current first-line therapy, gemcitabine. There are multiple factors that contribute to the chemoresistance observed in pancreatic cancer. Among them, desmoplasia has been increasingly seen as a significant contributor to chemoresistance. To overcome desmoplastic chemoresistance, several novel methods of treatment have been developed. Electroporation is one such novel treatment. High electrical fields are applied to cells to create pores that increase cell permeability. It has been previously demonstrated that electroporation enhances the therapeutic efficacy of anticancer drugs in pancreatic tumor models. Nanoparticle-based drug delivery systems constitute a second novel method to overcome desmoplastic chemoresistance. Due to their intrinsic design advantages, nanoparticles have been shown to increase the effectiveness of chemotherapeutic agents, while further reducing or even eliminating side effects. To date, there have been no studies evaluating the cumulative effect of combining both nanoparticle and electroporation strategies to overcome chemoresistance in PDAC. Our preliminary studies assessed the in vitro and in vivo uptake of doxorubicin-loaded iron oxide nanoparticles as a function of electroporation voltage and timing of administration in pancreatic adenocarcinoma cells. Our studies demonstrated that addition of electroporation to administration of nanoparticles significantly increased the amount of intracellular iron oxide nanoparticle uptake by a PANC-1 cell line in an athymic nude mouse model of PDAC. Further, electroporation-assisted nanoparticle uptake could be significantly altered by changing the timing of application of electroporation.

  9. Physiological Uptake in the Pancreatic Head on Somatostatin Receptor Scintigraphy Using [111In-DTPA]Octreotide: Incidence and Mechanism.

    Science.gov (United States)

    Brabander, Tessa; Teunissen, Jaap; Kwekkeboom, Dik

    2017-01-01

    Physiological uptake in the uncinate process or pancreatic head has been described with Ga-labeled PET tracers for somatostatin receptor imaging. In-DTPA-octreotide is the only registered radiopharmaceutical for the imaging of neuroendocrine tumors. We studied the uptake in this region of the pancreatic head on somatostatin receptor scintigraphy (SRS) using In-DTPA-octreotide in a large group of patients. Furthermore, known physiological and clinical characteristics are discussed in an attempt to elucidate this phenomenon. Four hundred seven patients underwent SRS using In-DTPA-octreotide in our department in 2014. After excluding patients with a known malignancy in or close to the pancreas, as well as all scans without SPECT/CT of the upper abdomen, we reviewed 178 scans in total. The uptake was graded on a 4-point scale that correlates the uptake in the pancreatic head to physiological uptake in the liver. Uptake in the region of the pancreatic head, including the uncinate process, was seen in 46 (26%) of 178 patients on SPECT/CT and in 12 patients (7%) on planar imaging. On SPECT/CT, uptake was lower than the liver in 26 patients (15%), equal to the liver in 17 patients (10%), and higher than the liver in 3 patients (2%). In patients with diabetes mellitus (DM), the incidence of uptake in the pancreatic head was 50% on SPECT/CT. Physiological uptake in the pancreatic head is seen on SPECT/CT with In-DTPA-octreotide in 26% of patients, and the incidence is doubled in patients with DM. Previous case reports showed uptake in the pancreatic head due to histologically proven pancreatic polypeptide (PP) cell hyperplasia. Also, patients with DM have elevated serum PP concentrations, which is likely due to PP cell hyperplasia. Because 90% of PP cells are present in the pancreatic head, PP cell hyperplasia is the most likely explanation for visualization of the pancreatic head on SRS in a substantial number of patients.

  10. Optimization and Mechanical Accuracy Reliability of a New Type of Forging Manipulator

    Institute of Scientific and Technical Information of China (English)

    CHEN Kang; MA Chunxiang; ZHENG Maoqi; GAO Feng

    2015-01-01

    Researches on forging manipulator have enormous influence on the development of the forging industry and national economy. Clamp device and lifting mechanism are the core parts of forging manipulator, and have been studied for longer time. However, the optimization and mechanical accuracy reliability of them are less analyzed. Based on General Function(GF) set and parallel mechanism theory, proper configuration of 10t forging manipulator is selected firstly. A new type of forging manipulator driven by cylinders is proposed. After solved mechanical analysis of manipulator’s core mechanisms, expressions of force of cylinders are carried out. In order to achieve smaller force afforded by cylinders and better mechanical characteristics, some particular sizes of core mechanisms are optimized intuitively through the combined use of the genetic algorithms(GA) and GUI interface in MATLAB. Comparing with the original mechanisms, optimized clamp saves at least 8 percent efforts and optimized lifting mechanism 20 percent under maximum working condition. Finally, considering the existed manufacture error of components, mechanical accuracy reliability of optimized clamp, lifting mechanism and whole manipulator are demonstrated respectively based on fuzzy reliability theory. Obtained results show that the accuracy reliability of optimized clamp is bigger than 0.991 and that of optimized lifting mechanism is 0.995. To the whole manipulator under maximum working condition, that value exceeds 0.986 4, which means that optimized manipulator has high motion accuracy and is reliable. A new intuitive method is created to optimize forging manipulator sizes efficiently and more practical theory is utilized to analyze mechanical accuracy reliability of forging manipulator precisely.

  11. Statistical Mechanics of Optimal Convex Inference in High Dimensions

    Science.gov (United States)

    Advani, Madhu; Ganguli, Surya

    2016-07-01

    A fundamental problem in modern high-dimensional data analysis involves efficiently inferring a set of P unknown model parameters governing the relationship between the inputs and outputs of N noisy measurements. Various methods have been proposed to regress the outputs against the inputs to recover the P parameters. What are fundamental limits on the accuracy of regression, given finite signal-to-noise ratios, limited measurements, prior information, and computational tractability requirements? How can we optimally combine prior information with measurements to achieve these limits? Classical statistics gives incisive answers to these questions as the measurement density α =(N /P )→∞ . However, these classical results are not relevant to modern high-dimensional inference problems, which instead occur at finite α . We employ replica theory to answer these questions for a class of inference algorithms, known in the statistics literature as M-estimators. These algorithms attempt to recover the P model parameters by solving an optimization problem involving minimizing the sum of a loss function that penalizes deviations between the data and model predictions, and a regularizer that leverages prior information about model parameters. Widely cherished algorithms like maximum likelihood (ML) and maximum-a posteriori (MAP) inference arise as special cases of M-estimators. Our analysis uncovers fundamental limits on the inference accuracy of a subclass of M-estimators corresponding to computationally tractable convex optimization problems. These limits generalize classical statistical theorems like the Cramer-Rao bound to the high-dimensional setting with prior information. We further discover the optimal M-estimator for log-concave signal and noise distributions; we demonstrate that it can achieve our high-dimensional limits on inference accuracy, while ML and MAP cannot. Intriguingly, in high dimensions, these optimal algorithms become computationally simpler than

  12. An Optimization Design of a Weft Insertion Mechanism for Rapier Looms

    Institute of Scientific and Technical Information of China (English)

    竺志超; 方志和

    2003-01-01

    By analyzing a combined and spatial 6-bar linkage weft insertion mechanism, its practical model for optimization design is set up and the modification of penalty strategy is put forward so that the genetic algorithm can be better used in optimization design for mechanisms with non- linear constraints. The design result is discussed.

  13. Research on Preference Polyhedron Model Based Evolutionary Multiobjective Optimization Method for Multilink Transmission Mechanism Conceptual Design

    Directory of Open Access Journals (Sweden)

    Haihua Zhu

    2016-01-01

    Full Text Available To make the optimal design of the multilink transmission mechanism applied in mechanical press, the intelligent optimization techniques are explored in this paper. A preference polyhedron model and new domination relationships evaluation methodology are proposed for the purpose of reaching balance among kinematic performance, dynamic performance, and other performances of the multilink transmission mechanism during the conceptual design phase. Based on the traditional evaluation index of single target of multicriteria design optimization, the robust metrics of the mechanism system and preference metrics of decision-maker are taken into consideration in this preference polyhedron model and reflected by geometrical characteristic of the model. At last, two optimized multilink transmission mechanisms are designed based on the proposed preference polyhedron model with different evolutionary algorithms, and the result verifies the validity of the proposed optimization method.

  14. Molecular Alignment and Orientation From Laser-Induced Mechanisms to Optimal Control

    CERN Document Server

    Atabek, O

    2002-01-01

    Genetic algorithms, as implemented in optimal control strategies, are currently successfully exploited in a wide range of problems in molecular physics. In this context, laser control of molecular alignment and orientation remains a very promising issue with challenging applications extending from chemical reactivity to nanoscale design. We emphasize the complementarity between basic quantum mechanisms monitoring alignment/orientation processes and optimal control scenarios. More explicitly, if on one hand we can help the optimal control scheme to take advantage of such mechanisms by appropriately building the targets and delineating the parameter sampling space, on the other hand we expect to learn, from optimal control results, some robust and physically sound dynamical mechanisms. We present basic mechanisms for alignment and orientation, such as pendular states accommodated by the molecule-plus-field effective potential and the "kick" mechanism obtained by a sudden excitation. Very interestingly, an optim...

  15. Validation of a Criterion for Cam Mechanisms Optimization Using Constraints upon Cam’s Curvature

    Directory of Open Access Journals (Sweden)

    Stelian Alaci

    2016-06-01

    Full Text Available For the mechanism with rotating cam and knife-edge follower, an optimization criterion by means of imposed constraints upon cam’s curvature is expressed in a special coordinate system. Thus, stating the optimization criterion in the coordinate system defined by the mechanisms constructive parameters -eccentricity and minimum follower’s stroke, a contour is obtained for any position of the mechanism. The optimization criterion assumes establishing the position of the characteristic point of the mechanism with respect to this contour. Fulfillment of optimization criterion assumes that the characteristic point is positioned in the same manner with respect to all contours. The optimization criterion is simplified when considering the envelope of the contours. The method is exemplified using two mechanisms, with the cams priori satisfying the criterion.

  16. Multi-objective optimization of flexure hinge mechanism considering thermal–mechanical coupling deformation and natural frequency

    Directory of Open Access Journals (Sweden)

    Lufan Zhang

    2017-01-01

    Full Text Available Flexure hinge mechanism plays a key part in realization of terminal nano-positioning. The performance of flexure hinge mechanism is determined by its positioning design. Based on the actual working conditions, its finite element model is built and calculated in ANSYS. Moreover, change trends of deformation and natural frequency with positioning design parameters are revealed. And sensitivity analysis is performed for exploration response to these parameters. These parameters are used to build four objective functions. To solve it conveniently, the multi-objective optimization problem is transferred to the form of single-objective function with constraints. An optimal mechanism is obtained by an optimization method combining ANSYS with MATLAB. Finite element numerical simulation has been carried out to demonstrate the superiority of the optimal flexure hinge mechanism, and the superiority can be further verified by experiment. Measurements and tests have been conducted at varying accelerations, velocities, and displacements, to quantify and characterize the amount of acceleration responses obtained from flexure hinge mechanism before and after optimization. Both time- and frequency-domain analyses of experimental data show that the optimal flexure hinge mechanism has superior effectiveness. It will provide a basic for realizing high acceleration and high precision positioning of macro–micro motion platform.

  17. Spring-joint method for topology optimization of planar passive compliant mechanisms

    Science.gov (United States)

    Jin, Mohui; Zhang, Xianmin; Zhu, Benliang; Wang, Nianfeng

    2013-11-01

    There is seldom approach developed for the initial topology design of flexure-based compliant mechanisms. The most commonly-used approaches, which start with an existing rigid-body mechanism, do not consider the performances between different topologies. Moreover, they rely heavily on the rigid-body topology, therefore limit the diversity of compliant mechanisms topology. To obtain the optimal initial topology of such mechanisms directly from problem specifications without referencing to the existing mechanism topologies, a spring-joint method is presented for a restricted class of the serial passive flexure-based compliant mechanisms, which are the building blocks of parallel compliant mechanisms. The topology of the compliant mechanisms is represented by a serial spring-joint mechanism(SSJM) that is a traditional rigid-body mechanism with a torsional spring acting on each joint, and is described by position vectors of the spring-joints. A simplified compliance matrix, determined by the position vectors, is used to characterize the tip of the SSJM kinematically, and is optimized to ensure the desired freedoms of the compliant mechanisms during optimization. The topology optimization problem is formulated as finding out the optimal position of the spring-joints in a blank design domain with an objective function derived from the simplified compliance matrix. In design examples, syntheses of the compliant mechanisms with both single freedom and two decoupled freedoms are presented to illustrate the proposed method. The proposed method provides a new way for the initial design of flexure-based compliant mechanisms.

  18. ‘Living’ PEGylation on gold nanoparticles to optimize cancer cell uptake by controlling targeting ligand and charge densities

    Science.gov (United States)

    Chen, Hongwei; Paholak, Hayley; Ito, Masayuki; Sansanaphongpricha, Kanokwan; Qian, Wei; Che, Yong; Sun, Duxin

    2013-09-01

    We report and demonstrate biomedical applications of a new technique—‘living’ PEGylation—that allows control of the density and composition of heterobifunctional PEG (HS-PEG-R; thiol-terminated poly(ethylene glycol)) on gold nanoparticles (AuNPs). We first establish ‘living’ PEGylation by incubating HS-PEG5000-COOH with AuNPs (˜20 nm) at increasing molar ratios from zero to 2000. This causes the hydrodynamic layer thickness to differentially increase up to 26 nm. The controlled, gradual increase in PEG-COOH density is revealed after centrifugation, based on the ability to re-suspend the pellet and increase the AuNP absorption. Using a fluorescamine-based assay we quantify differential HS-PEG5000-NH2 binding to AuNPs, revealing that it is highly efficient until AuNP saturation is reached. Furthermore, the zeta potential incrementally changes from -44.9 to +52.2 mV and becomes constant upon saturation. Using ‘living’ PEGylation we prepare AuNPs with different ratios of HS-PEG-RGD (RGD: Arg-Gly-Asp) and incubate them with U-87 MG (malignant glioblastoma) and non-target cells, demonstrating that targeting ligand density is critical to maximizing the efficiency of targeting of AuNPs to cancer cells. We also sequentially control the HS-PEG-R density to develop multifunctional nanoparticles, conjugating positively charged HS-PEG-NH2 at increasing ratios to AuNPs containing negatively charged HS-PEG-COOH to reduce uptake by macrophage cells. This ability to minimize non-specific binding/uptake by healthy cells could further improve targeted nanoparticle efficacy.

  19. 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.

  20. Optimization of the Switch Mechanism in a Circuit Breaker Using MBD Based Simulation

    Directory of Open Access Journals (Sweden)

    Jin-Seok Jang

    2015-01-01

    Full Text Available A circuit breaker is widely used to protect electric power system from fault currents or system errors; in particular, the opening mechanism in a circuit breaker is important to protect current overflow in the electric system. In this paper, multibody dynamic model of a circuit breaker including switch mechanism was developed including the electromagnetic actuator system. Since the opening mechanism operates sequentially, optimization of the switch mechanism was carried out to improve the current breaking time. In the optimization process, design parameters were selected from length and shape of each latch, which changes pivot points of bearings to shorten the breaking time. To validate optimization results, computational results were compared to physical tests with a high speed camera. Opening time of the optimized mechanism was decreased by 2.3 ms, which was proved by experiments. Switch mechanism design process can be improved including contact-latch system by using this process.

  1. Lie Algebroids in Classical Mechanics and Optimal Control

    Directory of Open Access Journals (Sweden)

    Eduardo Martínez

    2007-03-01

    Full Text Available We review some recent results on the theory of Lagrangian systems on Lie algebroids. In particular we consider the symplectic and variational formalism and we study reduction. Finally we also consider optimal control systems on Lie algebroids and we show how to reduce Pontryagin maximum principle.

  2. Optimal spinneret size for improvement of fiber's mechanical property

    Directory of Open Access Journals (Sweden)

    Yang Zhanping

    2013-01-01

    Full Text Available The effect of spinneret size and place on diameter and tensile property of cellulose acetate fibers is studied, and a criterion for the maximal breaking energy is obtained, and the spinneret distribution can be optimized for each spinning condition.

  3. Design and optimization of a bend-and-sweep compliant mechanism

    Science.gov (United States)

    Tummala, Y.; Frecker, M. I.; Wissa, A. A.; Hubbard, J. E., Jr.

    2013-09-01

    A novel contact aided compliant mechanism called bend-and-sweep compliant mechanism is presented in this paper. This mechanism has nonlinear stiffness properties in two orthogonal directions. An angled compliant joint (ACJ) is the fundamental element of this mechanism. Geometric parameters of ACJs determine the stiffness of the compliant mechanism. This paper presents the design and optimization of bend-and-sweep compliant mechanism. A multi-objective optimization problem was formulated for design optimization of the bend-and-sweep compliant mechanism. The objectives of the optimization problem were to maximize or minimize the bending and sweep displacements, depending on the situation, while minimizing the von Mises stress and mass of each mechanism. This optimization problem was solved using NSGA-II (a genetic algorithm). The results of this optimization for a single ACJ during upstroke and downstroke are presented in this paper. Results of two different loading conditions used during optimization of a single ACJ for upstroke are presented. Finally, optimization results comparing the performance of compliant mechanisms with one and two ACJs are also presented. It can be inferred from these results that the number of ACJs and the design of each ACJ determines the stiffness of the bend-and-sweep compliant mechanism. These mechanisms can be used in various applications. The goal of this research is to improve the performance of ornithopters by passively morphing their wings. In order to achieve a bio-inspired wing gait called continuous vortex gait, the wings of the ornithopter need to bend, and sweep simultaneously. This can be achieved by inserting the bend-and-sweep compliant mechanism into the leading edge wing spar of the ornithopters.

  4. Incentive Mechanism Design for Public Goods Provision: Price Cap Regulation and Optimal Regulation

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jun-jun; YIN Hong; WANG Xian-jia

    2005-01-01

    This paper studies the mechanism design that induces firms to provide public goods under two regulatory means: price cap regulation and optimal regulation, respectively. We first outline two models of monopoly regulation with unobservable marginal costs and effort, which can be regard as an optimal problem with dual restrictions. By solving this problem, we get the two optimal regulatory mechanisms to induce the provision of public goods. Further, by comparative statics, the conclusion is drawn that the welfare loss associated with price cap regulation, with respective to optimal regulation, increases more with increase of the expense of public goods.

  5. Heterogeneous reactions of methacrolein and methyl vinyl ketone: Kinetics and mechanisms of uptake and ozonolysis on silicon dioxide

    Science.gov (United States)

    Chen, Z. M.; Jie, C. Y.; Li, S.; Wang, H. L.; Wang, C. X.; Xu, J. R.; Hua, W.

    2008-11-01

    Methacrolein (MAC) and methyl vinyl ketone (MVK), two major first-generation products in the oxidation of isoprene, play important roles in tropospheric chemistry. However, little is known about their heterogeneous fate. Here we investigated the heterogeneous reactions of MAC and MVK on particles of silicon dioxide (SiO2), the major constituent of mineral dust in the troposphere, under simulated tropospheric conditions. We first investigated the adsorption and desorption processes. It was found that MAC and MVK molecules were adsorbed onto the surface of SiO2 particles by van der Waals forces and hydrogen bonding forces in a non-reactive state, and the presence of water vapor did not result in the formation of new substances but could decrease the adsorption ability by consuming isolated hydroxyl groups on the surface of SiO2 particles. The initial adsorption and desorption rates, initial uptake coefficients, and adsorption concentrations at equilibrium were determined at different relative humidities. Notably, in the desorption process, a considerable amount of MAC or MVK molecules remained on SiO2 particles in dry air but were almost completely desorbed in high-humid air. We also investigated the heterogeneous ozonolysis of MAC and MVK adsorbed onto SiO2 particles, determining product yields at different relative humidities. The heterogeneous ozonolysis of MAC and MVK adsorbed onto SiO2 particles yielded formaldehyde and methylglyoxal as the major secondary carbonyl products and formic acid and acetic acid as the major organic acid products, as in their gas-phase ozonolysis. However, the yield of two major organic peroxides, methyl hydroperoxide and hydroxymethyl hydroperoxide, was much greater in their heterogeneous ozonolysis than in their gas-phase ozonolysis. The mechanisms of heterogeneous ozonolysis of MAC and MVK onto the SiO2 surface are deduced.

  6. Prospects for optimizing soil microbial functioning to improve plant nutrient uptake and soil carbon sequestration under elevated CO2

    Science.gov (United States)

    Nie, M.; Pendall, E. G.

    2013-12-01

    Potential to mitigate climate change through increasing plant productivity and its carbon (C) input to soil may be limited by soil nitrogen (N) availability. Using a novel 13C-CO2 and 15N-soil dual labeling method, we investigated whether plant growth-promoting bacteria would interact with atmospheric CO2 concentration to alter plant productivity and soil C storage. We grew Bouteloua gracilis under ambient (380 ppm) or elevated CO2 (700 ppm) in climate-controlled chambers, and plant individuals were grown with or without Pseudomonas fluorescens inoculum, which can produce N catabolic enzymes. We observed that both eCO2 and P. fluorescens increased plant productivity and its C allocation to soil. P. fluorescens relative to eCO2 enhanced plant N uptake from soil organic matter, which highly correlated with soil N enzyme activities and rhizosphere exudate C. More importantly, P. fluorescens increased microbial biomass and deceased specific microbial respiration in comparison with eCO2. These results indicate that application of plant growth-promoting bacteria can increase microbial C utilization efficiency with subsequent N mineralization from soil organic matter, and may improve plant N availability and soil C sequestration. Together, our findings highlight the potential of plant growth-promoting bacteria for global change mitigation by terrestrial ecosystems.

  7. Quercetin and epigallocatechin gallate inhibit glucose uptake and metabolism by breast cancer cells by an estrogen receptor-independent mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Liliana, E-mail: lilianam87@gmail.com [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal); Araújo, Isabel, E-mail: isa.araujo013@gmail.com [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal); Costa, Tito, E-mail: tito.fmup16@gmail.com [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal); Correia-Branco, Ana, E-mail: ana.clmc.branco@gmail.com [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal); Faria, Ana, E-mail: anafaria@med.up.pt [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal); Chemistry Investigation Centre (CIQ), Faculty of Sciences of University of Porto, Rua Campo Alegre, 4169-007 Porto (Portugal); Faculty of Nutrition and Food Sciences of University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Martel, Fátima, E-mail: fmartel@med.up.pt [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal); Keating, Elisa, E-mail: keating@med.up.pt [Department of Biochemistry (U38-FCT), Faculty of Medicine of University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto (Portugal)

    2013-07-15

    In this study we characterized {sup 3}H-2-deoxy-D-glucose ({sup 3}H -DG) uptake by the estrogen receptor (ER)-positive MCF7 and the ER-negative MDA-MB-231 human breast cancer cell lines and investigated the effect of quercetin (QUE) and epigallocatechin gallate (EGCG) upon {sup 3}H-DG uptake, glucose metabolism and cell viability and proliferation. In both MCF7 and MDA-MB-231 cells {sup 3}H-DG uptake was (a) time-dependent, (b) saturable with similar capacity (V{sub max}) and affinity (K{sub m}), (c) potently inhibited by cytochalasin B, an inhibitor of the facilitative glucose transporters (GLUT), (d) sodium-independent and (e) slightly insulin-stimulated. This suggests that {sup 3}H-DG uptake by both cell types is mediated by members of the GLUT family, including the insulin-responsive GLUT4 or GLUT12, while being independent of the sodium-dependent glucose transporter (SGLT1). QUE and EGCG markedly and concentration-dependently inhibited {sup 3}H-DG uptake by MCF7 and by MDA-MB-231 cells, and both compounds blocked lactate production by MCF7 cells. Additionally, a 4 h-treatment with QUE or EGCG decreased MCF7 cell viability and proliferation, an effect that was more potent when glucose was available in the extracellular medium. Our results implicate QUE and EGCG as metabolic antagonists in breast cancer cells, independently of estrogen signalling, and suggest that these flavonoids could serve as therapeutic agents/adjuvants even for ER-negative breast tumors. -- Highlights: • Glucose uptake by MCF7 and MDA-MB-231 cells is mainly mediated by GLUT1. • QUE and EGCG inhibit cellular glucose uptake thus abolishing the Warburg effect. • This process induces cytotoxicity and proliferation arrest in MCF7 cells. • The flavonoids’ effects are independent of estrogen receptor signalling.

  8. Optimal trajectory generation for mechanical arms. M.S. Thesis

    Science.gov (United States)

    Iemenschot, J. A.

    1972-01-01

    A general method of generating optimal trajectories between an initial and a final position of an n degree of freedom manipulator arm with nonlinear equations of motion is proposed. The method is based on the assumption that the time history of each of the coordinates can be expanded in a series of simple time functions. By searching over the coefficients of the terms in the expansion, trajectories which minimize the value of a given cost function can be obtained. The method has been applied to a planar three degree of freedom arm.

  9. NOVEL METHOD OF REALIZING THE OPTIMAL TRANSMISSION OF THE CRANK-AND-ROCKER MECHANISM DESIGN

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel method of realizing the optimal transmission of the crank-and-rocker mechanism is presented. The optimal combination design is made by finding the related optimal transmission parameters. The diagram of the optimal transmission is drawn. In the diagram, the relation among minimum transmission angle, the coefficient of travel speed variation, the oscillating angle of the rocker and the length of the bars is shown, concisely, conveniently and directly. The method possesses the main characteristic. That it is to achieve the optimal transmission parameters under the transmission angle by directly choosing in the diagram, according to the given requirements. The characteristics of the mechanical transmission can be improved to gain the optimal transmission effect by the method. Especially, the method is simple and convenient in practical use.

  10. Optimal Design of a Cam Mechanism with Translating Flat-Face Follower using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    I. Tsiafis

    2013-12-01

    Full Text Available The optimum design of a cam mechanism is a time consuming task, due to the numerous alternatives considerations. In the present work, the problem of design parameters optimization of a cam mechanism with translating flat - face follower is investigated from a multi - objective point of view. The design parameters, just like the cam base circle radius, the follower face width and the follower offset can be determined considering as the optimization criteria minimization of the cam size, of the input torque and of the contact stress. During the optimization procedure, a number of constraints regarding the pressure angle, the contact stress, etcare taken into account. The optimization approach, based on genetic algorithm, is applied to find the optimal solutions with respect to the a fore - mentioned objective function and to Ensure the kinematic requirements. Finally, the dynamic behavior of the designed cam mechanism is investigated considering the frictional forces.

  11. A new paradigm for aptamer therapeutic AS1411 action: Uptake by macropinocytosis and its stimulation by a nucleolin-dependent mechanism

    OpenAIRE

    Reyes-Reyes, E. Merit; Teng, Yun; Bates, Paula J.

    2010-01-01

    AS1411 is a first-in-class anticancer agent, currently in Phase II clinical trials. It is a quadruplex-forming oligodeoxynucleotide that binds to nucleolin as an aptamer, but its mechanism of action is not completely understood. Mechanistic insights could lead to clinically useful markers for AS1411 response and to novel targeted therapies. Previously, we proposed a model where cell surface nucleolin serves as the receptor for AS1411, leading to selective uptake in cancer cells. Here, we comp...

  12. Analysis of Nonlinear Pharmacokinetics of a Highly Albumin-Bound Compound: Contribution of Albumin-Mediated Hepatic Uptake Mechanism.

    Science.gov (United States)

    Fukuchi, Yukina; Toshimoto, Kota; Mori, Takanori; Kakimoto, Keisuke; Tobe, Yoshifusa; Sawada, Takeshi; Asaumi, Ryuta; Iwata, Takeyuki; Hashimoto, Yoshitaka; Nunoya, Ken-Ichi; Imawaka, Haruo; Miyauchi, Seiji; Sugiyam, Yuichi

    2017-09-01

    The cause of nonlinear pharmacokinetics (PK) (more than dose-proportional increase in exposure) of a urea derivative under development (compound A: anionic compound [pKa: 4.4]; LogP: 6.5; and plasma protein binding: 99.95%) observed in a clinical trial was investigated. Compound A was metabolized by CYP3A4, UGT1A1, and UGT1A3 with unbound Km of 3.3-17.8 μmol/L. OATP1B3-mediated uptake of compound A determined in the presence of human serum albumin (HSA) showed that unbound Km and Vmax decreased with increased HSA concentration. A greater decrease in unbound Km than in Vmax resulted in increased uptake clearance (Vmax/unbound Km) with increased HSA concentration, the so-called albumin-mediated uptake. At 2% HSA concentration, unbound Km was 0.00657 μmol/L. A physiologically based PK model assuming saturable hepatic uptake nearly replicated clinical PK of compound A. Unbound Km for hepatic uptake estimated from the model was 0.000767 μmol/L, lower than the in vitro unbound Km at 2% HSA concentration, whereas decreased Km with increased concentration of HSA in vitro indicated lower Km at physiological HSA concentration (4%-5%). In addition, unbound Km values for metabolizing enzymes were much higher than unbound Km for OATP1B3, indicating that the nonlinear PK of compound A is primarily attributed to saturated OATP1B3-mediated hepatic uptake of compound A. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  13. Mechanisms of peer tutoring on optimizing cognitive load during knowledge sharing in learning networks

    NARCIS (Netherlands)

    Hsiao, Amy; Brouns, Francis; Sloep, Peter

    2010-01-01

    Hsiao, Y. P., Brouns, F., & Sloep, P. B. (2010, 15 April). Mechanisms of peer tutoring on optimizing cognitive load during knowledge sharing in learning networks. Presentation at NELLL Colloqium, Heerlen, The Netherlands: Open University of the Netherlands.

  14. Combined holographic-mechanical optical tweezers: Construction, optimization, and calibration

    Energy Technology Data Exchange (ETDEWEB)

    Hanes, Richard D. L.; Jenkins, Matthew C.; Egelhaaf, Stefan U. [Condensed Matter Physics Laboratory, Heinrich-Heine University, 40225 Duesseldorf (Germany)

    2009-08-15

    A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it is common to use the SLM at an incidence angle of 45 deg., smaller angles give a full 2{pi} phase shift and an output intensity which is less dependent on the magnitude of the phase shift. The traps were calibrated using an active oscillatory technique and a passive probability distribution method.

  15. Optimal design of a novel remote center-of-motion mechanism for minimally invasive surgical robot

    Science.gov (United States)

    Sun, Jingyuan; Yan, Zhiyuan; Du, Zhijiang

    2017-06-01

    Surgical robot with a remote center-of-motion (RCM) plays an important role in minimally invasive surgery (MIS) field. To make the mechanism has high flexibility and meet the demand of movements during processing of operation, an optimized RCM mechanism is proposed in this paper. Then, the kinematic performance and workspace are analyzed. Finally, a new optimization objective function is built by using the condition number index and the workspace index.

  16. Water uptake in the cat flea Ctenocephalides felis (Pulicidae: Siphonaptera).

    Science.gov (United States)

    Thiemann, T; Fielden, L J; Kelrick, M I

    2003-12-01

    To counteract water loss due to excretion, cuticular transpiration and respiration, various groups of arthropods have developed mechanisms for active uptake of water vapor from unsaturated air. In this study, active uptake capabilities and water loss rates were examined in the various developmental stages of the cat flea, Ctenocephalides felis. To determine critical equilibrium humidity, the lowest relative humidity at which active water uptake can occur, pre-desiccated immature and adult fleas were placed in a series of humidity regimes ranging from 44 to 93% RH. Active uptake occurred in larval stages at relative humidities above 53% and in pre-pupae at 75-93% RH. Pupae and adults did not demonstrate active uptake at any humidity. Optimal uptake for larvae occurred between 20 and 30 degrees C. When placed over Drierite (water loss than pre-pupal and pupal stages. Active water uptake is necessary to ensure proper development of the larvae of C. felis. Active uptake ceases after the larval-pupal ecdysis and it appears that adults have lost the ability to actively uptake water.

  17. Stiffness, Workspace Analysis and Optimization for 3UPU Parallel Robot Mechanism

    Directory of Open Access Journals (Sweden)

    Cui Guohua

    2013-09-01

    Full Text Available In this paper, an approach based on the particle swarm optimization is used to optimize the workspace and global stiffness of the 3UPU mechanism simultaneously due to the fact that the workspace is affected while optimizing the stiffness of the mechanism and vice versa. When optimizing one particular performance, one needs to have an objective function. Here the workspace volume of the mechanism is used as an objective function to evaluate the workspace performance of the mechanism. The leading diagonal elements of the stiffness matrix represent pure stiffness in each direction, but this stiffness changes when the moving platform position changes. We call this stiffness as local stiffness. When using the local stiffness as an objective function for stiffness optimization, it can only represent the stiffness in one particular position. Here the global stiffness of the mechanism is used as an objective function to optimize the stiffness of the mechanism. The global stiffness represents mean stiffness over the workspace.  

  18. Parallel iterative reaction path optimization in ab initio quantum mechanical/molecular mechanical modeling of enzyme reactions.

    Science.gov (United States)

    Liu, Haiyan; Lu, Zhenyu; Cisneros, G Andres; Yang, Weitao

    2004-07-08

    The determination of reaction paths for enzyme systems remains a great challenge for current computational methods. In this paper we present an efficient method for the determination of minimum energy reaction paths with the ab initio quantum mechanical/molecular mechanical approach. Our method is based on an adaptation of the path optimization procedure by Ayala and Schlegel for small molecules in gas phase, the iterative quantum mechanical/molecular mechanical (QM/MM) optimization method developed earlier in our laboratory and the introduction of a new metric defining the distance between different structures in the configuration space. In this method we represent the reaction path by a discrete set of structures. For each structure we partition the atoms into a core set that usually includes the QM subsystem and an environment set that usually includes the MM subsystem. These two sets are optimized iteratively: the core set is optimized to approximate the reaction path while the environment set is optimized to the corresponding energy minimum. In the optimization of the core set of atoms for the reaction path, we introduce a new metric to define the distances between the points on the reaction path, which excludes the soft degrees of freedom from the environment set and includes extra weights on coordinates describing chemical changes. Because the reaction path is represented by discrete structures and the optimization for each can be performed individually with very limited coupling, our method can be executed in a natural and efficient parallelization, with each processor handling one of the structures. We demonstrate the applicability and efficiency of our method by testing it on two systems previously studied by our group, triosephosphate isomerase and 4-oxalocrotonate tautomerase. In both cases the minimum energy paths for both enzymes agree with the previously reported paths.

  19. CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.

  20. Design of synchromesh mechanism to optimization manual transmission's electric vehicle

    Science.gov (United States)

    Zainuri, Fuad; Sumarsono, Danardono A.; Adhitya, Muhammad; Siregar, Rolan

    2017-03-01

    Significant research has been attempted on a vehicle that lead to the development of transmission that can reduce energy consumption and improve vehicle efficiency. Consumers also expect safety, convenience, and competitive prices. Automatic transmission (AT), continuously variable transmission (CVT), and dual clutch transmission (DCT) is the latest transmission developed for road vehicle. From literature reviews that have been done that this transmission is less effective on electric cars which use batteries as a power source compared to type manual transmission, this is due to the large power losses when making gear changes. Zeroshift system is the transmission can do shift gears with no time (zero time). It was developed for the automatic manual transmission, and this transmission has been used on racing vehicles to eliminate deceleration when gear shift. Zeroshift transmission still use the clutch to change gear in which electromechanical be used to replace the clutch pedal. Therefore, the transmission is too complex for the transmission of electric vehicles, but its mechanism is considered very suitable to increase the transmission efficiency. From this idea, a new innovation design transmission will be created to electric car. The combination synchromesh with zeroshift mechanism for the manual transmission is a transmission that is ideal for improving the transmission efficiency. Installation synchromesh on zeroshift mechanism is expected to replace the function of the clutch MT, and assisted with the motor torque setting when to change gear. Additionally to consider is the weight of the transmission, ease of manufacturing, ease of installation with an electric motor, as well as ease of use by drivers is a matter that must be done to obtain a new transmission system that is suitable for electric cars.

  1. Analysis and optimal design of an underactuated finger mechanism for LARM hand

    Science.gov (United States)

    Yao, Shuangji; Ceccarelli, Marco; Carbone, Giuseppe; Zhan, Qiang; Lu, Zhen

    2011-09-01

    This paper aims to present general design considerations and optimality criteria for underactuated mechanisms in finger designs. Design issues related to grasping task of robotic fingers are discussed. Performance characteristics are outlined as referring to several aspects of finger mechanisms. Optimality criteria of the finger performances are formulated after careful analysis. A general design algorithm is summarized and formulated as a suitable multi-objective optimization problem. A numerical case of an underactuated robot finger design for Laboratory of Robotics and Mechatronics (LARM) hand is illustrated with the aim to show the practical feasibility of the proposed concepts and computations.

  2. Optimal Determination of Respiratory Airflow Patterns Using a Nonlinear Multicompartment Model for a Lung Mechanics System

    Directory of Open Access Journals (Sweden)

    Hancao Li

    2012-01-01

    Full Text Available We develop optimal respiratory airflow patterns using a nonlinear multicompartment model for a lung mechanics system. Specifically, we use classical calculus of variations minimization techniques to derive an optimal airflow pattern for inspiratory and expiratory breathing cycles. The physiological interpretation of the optimality criteria used involves the minimization of work of breathing and lung volume acceleration for the inspiratory phase, and the minimization of the elastic potential energy and rapid airflow rate changes for the expiratory phase. Finally, we numerically integrate the resulting nonlinear two-point boundary value problems to determine the optimal airflow patterns over the inspiratory and expiratory breathing cycles.

  3. Optimal determination of respiratory airflow patterns using a nonlinear multicompartment model for a lung mechanics system.

    Science.gov (United States)

    Li, Hancao; Haddad, Wassim M

    2012-01-01

    We develop optimal respiratory airflow patterns using a nonlinear multicompartment model for a lung mechanics system. Specifically, we use classical calculus of variations minimization techniques to derive an optimal airflow pattern for inspiratory and expiratory breathing cycles. The physiological interpretation of the optimality criteria used involves the minimization of work of breathing and lung volume acceleration for the inspiratory phase, and the minimization of the elastic potential energy and rapid airflow rate changes for the expiratory phase. Finally, we numerically integrate the resulting nonlinear two-point boundary value problems to determine the optimal airflow patterns over the inspiratory and expiratory breathing cycles.

  4. The importance of reductive mechanisms for intestinal uptake of iron from ferric maltol and ferric nitrilotriacetic acid (NTA).

    Science.gov (United States)

    Barrand, M A; Hider, R C; Callingham, B A

    1990-04-01

    Intestinal iron absorption is thought to proceed with iron mainly in the ferrous form, yet the novel iron complex, ferric maltol is an effective oral preparation. Although possessing a high oil: water partition coefficient, ferric maltol does not diffuse across the intestine but donates its iron to the endogenous uptake system. Reduction of the ferric iron in the gut lumen appears to precede iron uptake both from ferric maltol and from ferric nitrilotriacetic acid (NTA) which is a non-penetrating iron ligand. Uptake of radiolabelled iron (59Fe) into isolated fragments of rat small intestine was inhibited by the ferrous chelator, bathophenanthroline sulphonate (BPS) and enhanced at low concentrations by the reducing agent ascorbic acid. Spectrophotometric evidence was obtained that ferrous ions are generated from these ferric complexes in the presence of ascorbic acid and other reducing agents. The rate of ferrous ion formation was independent of ferric maltol concentration at low ascorbic acid levels and decreased with increasing ferric maltol concentration at higher levels of ascorbate. Maltol has a high affinity for ferric ions and may delay reduction at higher concentrations. By contrast, a higher rate of ferrous ion generation was seen with ferric NTA and this increased with iron ligand concentration. Washings from the intestinal lumen also brought about ferrous ion formation from these ferric ligands. Gel filtration revealed these reducing factors to be of low molecular weight. The washings, however, interfered with 59Fe uptake into the isolated fragments, but when reducing fractions only from the filtered washings were used, enhanced iron uptake was seen.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Multi-objective behavioural mechanisms are adopted by foraging animals to achieve several optimality goals simultaneously.

    Science.gov (United States)

    Wajnberg, Eric

    2012-03-01

    1. Animals foraging for resources are under a variety of selective pressures, and separate optimality models have been developed predicting the optimal reproductive strategies they should adopt. 2. In most cases, the proximate behavioural mechanisms adopted to achieve such optimality goals have been identified. This is the case, for example, for optimal patch time and sex allocation in insect parasitoids. However, behaviours modelled within this framework have mainly been studied separately, even though real animals have to optimize some behaviours simultaneously. 3. For this reason, it would be better if proximate behavioural rules were designed to attain several goals simultaneously. Despite their importance, such multi-objective proximate rules remain to be discovered. 4. Based on experiments on insect parasitoids that simultaneously examine their optimal patch time and sex allocation strategies, it is shown here that animals can adopt multi-objective behavioural mechanisms that appear consistent with the two optimal goals simultaneously. 5. Results of computer simulations demonstrate that these behavioural mechanisms are indeed consistent with optimal reproductive strategies and have thus been most likely selected over the course of the evolutionary time.

  6. Porosity and mechanically optimized PLGA based in situ hardening systems.

    Science.gov (United States)

    Schloegl, W; Marschall, V; Witting, M Y; Volkmer, E; Drosse, I; Leicht, U; Schieker, M; Wiggenhorn, M; Schaubhut, F; Zahler, S; Friess, W

    2012-11-01

    Goal of the present study was to develop and to characterize in situ-hardening, porous PLGA-based systems for their future application as bone grafting materials. Therefore, we investigated the precipitation behavior of formulations containing PLGA and a water-miscible solvent, DMSO, PEG 400, and NMP. To increase porosity, a pore forming agent (NaCMC) was added and to enhance mechanical properties of the system, an inorganic filler (α-TCP) was incorporated. The behavior upon contact with water and the influence of the prior addition of aqueous media on the morphology of the corresponding hardened implants were investigated. We proved cell-compatibility by live/dead assays for the hardened porous polymer/ceramic-composite scaffolds. The IsHS formulations can therefore be used to manufacture hardened scaffolds ex vivo by using molds with the desired shape and size. Cells were further successfully incorporated into the IsHS by precultivating the cells on the α-TCP-powder prior to their admixing to the formulation. However, cell viability could not be maintained due to toxicity of the tested solvents. But, the results demonstrate that in vivo cells should well penetrate, adhere, and proliferate in the hardened scaffolds. Consequently, we consider the in situ hardening system being an excellent candidate as a filling material for non-weight-bearing orthopedic indications, as the resulting properties of the hardened implant fulfill indication-specific needs like mechanical stability, elasticity, and porosity.

  7. Interior and exterior ballistics coupled optimization with constraints of attitude control and mechanical-thermal conditions

    Science.gov (United States)

    Liang, Xin-xin; Zhang, Nai-min; Zhang, Yan

    2016-07-01

    For solid launch vehicle performance promotion, a modeling method of interior and exterior ballistics associated optimization with constraints of attitude control and mechanical-thermal condition is proposed. Firstly, the interior and external ballistic models of the solid launch vehicle are established, and the attitude control model of the high wind area and the stage of the separation is presented, and the load calculation model of the drag reduction device is presented, and thermal condition calculation model of flight is presented. Secondly, the optimization model is established to optimize the range, which has internal and external ballistic design parameters as variables selected by sensitivity analysis, and has attitude control and mechanical-thermal conditions as constraints. Finally, the method is applied to the optimal design of a three stage solid launch vehicle simulation with differential evolution algorithm. Simulation results are shown that range capability is improved by 10.8%, and both attitude control and mechanical-thermal conditions are satisfied.

  8. Carrots and Sticks as Incentive Mechanisms for the Optimal Initiation of Insolvency Proceedings

    Directory of Open Access Journals (Sweden)

    Cepec Jaka

    2016-06-01

    Full Text Available The pursuit of ex-ante efficiency in bankruptcy law has been widely discussed in recent law and economics literature. However, the exact incentive mechanisms inducing the optimal commencement of bankruptcy proceedings have generally been exempted from the current scholarly debate. Using the law and economics tools and comparative analysis, this paper seeks to identify insolvency-specific optimal incentive mechanisms, while using the general theory on carrots and sticks in legal regulations. The paper suggests the employment of mixed-sticks-and-carrots incentive mechanisms for managers’ prompt proposals of insolvency proceedings as an optimal regulatory response. Moreover, the article provides comparative evidence that exclusive use of sticks or carrots in French, German, US, English, and Slovenian legal systems results in sub-optimal initiation of insolvency proceedings and may also induce adverse effects on prompt initiation.

  9. Multi-Objective Optimization of Mechanical Running Conditions of Large Scale Statically Indeterminate Rotary Kiln

    Institute of Scientific and Technical Information of China (English)

    Hu Xiaoping; Xiao Yougang; Wang Guangbin

    2006-01-01

    Combined with the second rotary kiln of Alumina Factory in Great Wall Aluminum Company, the mechanics characteristics of statically indeterminate large-scale rotary kiln with variable cross-sections is analyzed. In order to adjusting the runing axis of rotary kiln, taking the force equilibrium of the rollers and the minimum of relative axis deflection as the optimization goal, the multi-objective optimization model of mechanical running conditions of kiln rotary is set up. The mechanical running conditions of the second rotary kiln after multi-objective optimization adjustment are compared with those before adjustment and after routine adjustment. It shows that multi-objective optimization adjustment can make axis as direct as possible and can distribute kiln loads equally.

  10. Cellular entry of ebola virus involves uptake by a macropinocytosis-like mechanism and subsequent trafficking through early and late endosomes.

    Directory of Open Access Journals (Sweden)

    Mohammad F Saeed

    2010-09-01

    Full Text Available Zaire ebolavirus (ZEBOV, a highly pathogenic zoonotic virus, poses serious public health, ecological and potential bioterrorism threats. Currently no specific therapy or vaccine is available. Virus entry is an attractive target for therapeutic intervention. However, current knowledge of the ZEBOV entry mechanism is limited. While it is known that ZEBOV enters cells through endocytosis, which of the cellular endocytic mechanisms used remains unclear. Previous studies have produced differing outcomes, indicating potential involvement of multiple routes but many of these studies were performed using noninfectious surrogate systems such as pseudotyped retroviral particles, which may not accurately recapitulate the entry characteristics of the morphologically distinct wild type virus. Here we used replication-competent infectious ZEBOV as well as morphologically similar virus-like particles in specific infection and entry assays to demonstrate that in HEK293T and Vero cells internalization of ZEBOV is independent of clathrin, caveolae, and dynamin. Instead the uptake mechanism has features of macropinocytosis. The binding of virus to cells appears to directly stimulate fluid phase uptake as well as localized actin polymerization. Inhibition of key regulators of macropinocytosis including Pak1 and CtBP/BARS as well as treatment with the drug EIPA, which affects macropinosome formation, resulted in significant reduction in ZEBOV entry and infection. It is also shown that following internalization, the virus enters the endolysosomal pathway and is trafficked through early and late endosomes, but the exact site of membrane fusion and nucleocapsid penetration in the cytoplasm remains unclear. This study identifies the route for ZEBOV entry and identifies the key cellular factors required for the uptake of this filamentous virus. The findings greatly expand our understanding of the ZEBOV entry mechanism that can be applied to development of new

  11. Fuzzy Optimization of an Elevator Mechanism Applying the Genetic Algorithm and Neural Networks

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Considering the indefinite character of the value of design parameters and being satisfied with load-bearing capacity and stiffness, the fuzzy optimization mathematical model is set up to minimize the volume of tooth corona of a worm gear in an elevator mechanism. The method of second-class comprehensive evaluation was used based on the optimal level cut set, thus the optimal level value of every fuzzy constraint can be attained; the fuzzy optimization is transformed into the usual optimization.The Fast Back Propagation of the neural networks algorithm are adopted to train feed-forward networks so as to fit a relative coefficient. Then the fitness function with penalty terms is built by a penalty strategy, a neural networks program is recalled, and solver functions of the Genetic Algorithm Toolbox of Matlab software are adopted to solve the optimization model.

  12. Mechanism of riboflavin uptake by cultured human retinal pigment epithelial ARPE-19 cells: possible regulation by an intracellular Ca2+-calmodulin-mediated pathway.

    Science.gov (United States)

    Said, Hamid M; Wang, Shuling; Ma, Thomas Y

    2005-07-15

    In mammalian cells (including those of the ocular system), the water-soluble vitamin B2 (riboflavin, RF) assumes an essential role in a variety of metabolic reactions and is critical for normal cellular functions, growth and development. Cells of the human retinal pigment epithelium (hRPE) play an important role in providing a sufficient supply of RF to the retina, but nothing is known about the mechanism of the vitamin uptake by these cells and its regulation. Our aim in the present study was to address this issue using the hRPE ARPE-19 cells as the retinal epithelial model. Our results show RF uptake in the hRPE to be: (1) energy and temperature dependent and occurring without metabolic alteration in the transported substrate, (2) pH but not Na+ dependent, (3) saturable as a function of concentration with an apparent Km of 80 +/- 14 nM, (4) trans-stimulated by unlabelled RF and its structural analogue lumiflavine, (5) cis-inhibited by the RF structural analogues lumiflavine and lumichrome but not by unrelated compounds, and (6) inhibited by the anion transport inhibitors 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS) as well as by the Na+ -H+ exchange inhibitor amiloride and the sulfhydryl group inhibitor p-chloromercuriphenylsulphonate (p-CMPS). Maintaining the hRPE cells in a RF-deficient medium led to a specific and significant up-regulation in RF uptake which was mediated via changes in the number and affinity of the RF uptake carriers. While modulating the activities of intracellular protein kinase A (PKA)-, protein kinase C (PKC)-, protein tyrosine kinase (PTK)-, and nitric oxide (NO)-mediated pathways were found to have no role in regulating RF uptake, a role for the Ca2+ -calmodulin-mediated pathway was observed. These studies demonstrate for the first time the involvement of a specialized carrier-mediated mechanism for RF uptake by hRPE cells and show that the process is

  13. Optimization of release locations for small self-stress large stiffness flexure mechanisms

    NARCIS (Netherlands)

    Brouwer, D.M.; Boer, S.E.; Meijaard, J.P.; Aarts, R.G.K.M.

    2013-01-01

    In overconstrained mechanisms inherent alignment errors cause self-stress. The level of stress can be reduced by inserting flexure releases making the mechanism exactly constrained. The location and orientation of releases can be optimized for a combination of minimum self-stress and maximum stiffne

  14. Using Positive Deviance to Understand the Uptake of Optimal Infant and Young Child Feeding Practices by Mothers in an Urban Slum of Mumbai.

    Science.gov (United States)

    D'Alimonte, M R; Deshmukh, D; Jayaraman, A; Chanani, S; Humphries, D L

    2016-06-01

    Objectives Positive deviance research seeks out well-nourished children living in disadvantaged contexts to understand local growth-promoting behaviors. This study explored the factors that influence the uptake of infant and young child feeding behaviors among mothers. Methods Children with a height-for-age z-score (HAZ) > 0 (n = 10) or a HAZ Theory of qualitative research. Results Positive deviant mothers (those with children with a HAZ > 0) largely exhibited optimal infant and young child feeding practices explained by maternal information seeking behaviors; mothers acknowledging the importance of maternal health; and social support. The relationship between mother and health worker seemed to influence how well they listened to the health workers' recommendations. Across all households, the daily consumption of high-energy, processed foods was apparent. Conclusions Practical considerations include exploring how to tailor CMAM programs to include social support and counseling training for health workers to engage more closely with mothers; exploring the feasibility of a women's social group for mothers to share information on child rearing; and teaching mothers about healthy eating and the link between nutrition and health.

  15. Application of Response Surface Methodology for Optimization of Urea Grafted Multiwalled Carbon Nanotubes in Enhancing Nitrogen Use Efficiency and Nitrogen Uptake by Paddy Plants

    Directory of Open Access Journals (Sweden)

    Norazlina Mohamad Yatim

    2016-01-01

    Full Text Available Efficient use of urea fertilizer (UF as important nitrogen (N source in the world’s rice production has been a concern. Carbon-based materials developed to improve UF performance still represent a great challenge to be formulated for plant nutrition. Advanced N nanocarrier is developed based on functionalized multiwall carbon nanotubes (f-MWCNTs grafted with UF to produce urea-multiwall carbon nanotubes (UF-MWCNTs for enhancing the nitrogen uptake (NU and use efficiency (NUE. The grafted N can be absorbed and utilized by rice efficiently to overcome the N loss from soil-plant systems. The individual and interaction effect between the specified factors of f-MWCNTs amount (0.10–0.60 wt% and functionalization reflux time (12–24 hrs with the corresponding responses (NUE, NU were structured via the Response Surface Methodology (RSM based on five-level CCD. The UF-MWCNTs with optimized 0.5 wt% f-MWCNTs treated at 21 hrs reflux time achieve tremendous NUE up to 96% and NU at 1180 mg/pot. Significant model terms (p value < 0.05 for NUE and NU responses were confirmed by the ANOVA. Homogeneous dispersion of UF-MWCNTs was observed via FESEM and TEM. The chemical changes were monitored by FT-IR and Raman spectroscopy. Hence, this UF-MWCNTs’ approach provides a promising strategy in enhancing plant nutrition for rice.

  16. Optimization of pulsed TIG welding process parameters on mechanical properties of AA 5456 Aluminum alloy weldments

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. [Department of Mechanical Engineering, National Institute of Technology, Warangal 506 004 (India)], E-mail: adepu_kumar7@yahoo.co.in; Sundarrajan, S. [Scientist ' G' , Defence Research and Development Laboratory, Hyderabad 500 028 (India)

    2009-04-15

    The present work pertains to the improvement of mechanical properties of AA 5456 Aluminum alloy welds through pulsed tungsten inert gas (TIG) welding process. Taguchi method was employed to optimize the pulsed TIG welding process parameters of AA 5456 Aluminum alloy welds for increasing the mechanical properties. Regression models were developed. Analysis of variance was employed to check the adequacy of the developed models. The effect of planishing on mechanical properties was also studied and observed that there was improvement in mechanical properties. Microstructures of all the welds were studied and correlated with the mechanical properties.

  17. OPTIMAL KINEMATIC DESIGN OF A CAR AXLE GUIDING MECHANISM IN MBS SOFTWARE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Cătălin ALEXANDRU

    2015-05-01

    Full Text Available This work deals with the optimal kinematic design of the guiding mechanism used for the rear axle of a motor vehicle. A guiding mechanism of type 2S1C (S - sphere, C - circle is taken into consideration, the optimization study being conducted by using the multi-body systems (MBS software environment ADAMS of MSC. The global cartesian coordinates of some design points (the locations of the joints between the guiding arms and car body are used as independent design variables for the optimization study. The main design objectives refer to the longitudinal displacement of the axle and its proper rotation (around the transversal axis, the kinematic optimization goal being to minimize these variations.

  18. A New Chaotic Genetic Hybrid Algorithm and Its Applications in Mechanical Optimization Design

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-min; DAI Yi

    2010-01-01

    A new chaotic genetic hybrid algorithm (CGHA) based on float point coding was put forward in this paper.Firstly, it used chaos optimization to search coarsely and produced a better initial population. Then, a power function carri-er was adopted to improve the ergodicity and the sufficiency of the chaos optimization. Secondly, the genetic algorithm (GA) was used to search finely and guaranteed the population's evolution. To avoid the search being trapped in local minimum, a chaos degenerate mutation operator was designed to make the search converge to a global optimum quickly. Finally, CGHA was used to solve a typical mechanical optimization problem of shear stress checking for a cylinder helix spring.Compared with traditional penalty function method, chaos-Powell hybrid algorithm and standard GA, CGHA shows better performance in solution precision and convergence speed than those of the algorithms. Therefore, CGHA is a new effective way to solve the problems in mechanical optimization design.

  19. Optimization and analysis of large chemical kinetic mechanisms using the solution mapping method - Combustion of methane

    Science.gov (United States)

    Frenklach, Michael; Wang, Hai; Rabinowitz, Martin J.

    1992-01-01

    A method of systematic optimization, solution mapping, as applied to a large-scale dynamic model is presented. The basis of the technique is parameterization of model responses in terms of model parameters by simple algebraic expressions. These expressions are obtained by computer experiments arranged in a factorial design. The developed parameterized responses are then used in a joint multiparameter multidata-set optimization. A brief review of the mathematical background of the technique is given. The concept of active parameters is discussed. The technique is applied to determine an optimum set of parameters for a methane combustion mechanism. Five independent responses - comprising ignition delay times, pre-ignition methyl radical concentration profiles, and laminar premixed flame velocities - were optimized with respect to thirteen reaction rate parameters. The numerical predictions of the optimized model are compared to those computed with several recent literature mechanisms. The utility of the solution mapping technique in situations where the optimum is not unique is also demonstrated.

  20. Drosophila lipophorin receptors mediate the uptake of neutral lipids in oocytes and imaginal disc cells by an endocytosis-independent mechanism.

    Directory of Open Access Journals (Sweden)

    Esmeralda Parra-Peralbo

    2011-02-01

    Full Text Available Lipids are constantly shuttled through the body to redistribute energy and metabolites between sites of absorption, storage, and catabolism in a complex homeostatic equilibrium. In Drosophila, lipids are transported through the hemolymph in the form of lipoprotein particles, known as lipophorins. The mechanisms by which cells interact with circulating lipophorins and acquire their lipidic cargo are poorly understood. We have found that lipophorin receptor 1 and 2 (lpr1 and lpr2, two partially redundant genes belonging to the Low Density Lipoprotein Receptor (LDLR family, are essential for the efficient uptake and accumulation of neutral lipids by oocytes and cells of the imaginal discs. Females lacking the lpr2 gene lay eggs with low lipid content and have reduced fertility, revealing a central role for lpr2 in mediating Drosophila vitellogenesis. lpr1 and lpr2 are transcribed into multiple isoforms. Interestingly, only a subset of these isoforms containing a particular LDLR type A module mediate neutral lipid uptake. Expression of these isoforms induces the extracellular stabilization of lipophorins. Furthermore, our data indicate that endocytosis of the lipophorin receptors is not required to mediate the uptake of neutral lipids. These findings suggest a model where lipophorin receptors promote the extracellular lipolysis of lipophorins. This model is reminiscent of the lipolytic processing of triglyceride-rich lipoproteins that occurs at the mammalian capillary endothelium, suggesting an ancient role for LDLR-like proteins in this process.

  1. Optimal Manoeuvres of Underactuated Linear Mechanical Systems: The Case of Controlling Gantry Crane Operations

    Directory of Open Access Journals (Sweden)

    S. Woods

    2014-01-01

    Full Text Available A method of solving optimal manoeuvre control of linear underactuated mechanical systems is presented. The nonintegrable constraints present in such systems are handled by adding dummy actuators and then by applying Lagrange multipliers to reduce their action to zero. The open- and closed-loop control schemes can be analyzed. The method, referred to as the constrained modal space optimal control (CMSOC, is illustrated in the examples of gantry crane operations.

  2. Optimal Manoeuvres of Underactuated Linear Mechanical Systems: The Case of Controlling Gantry Crane Operations

    OpenAIRE

    Woods, S; Szyszkowski, W.

    2014-01-01

    A method of solving optimal manoeuvre control of linear underactuated mechanical systems is presented. The nonintegrable constraints present in such systems are handled by adding dummy actuators and then by applying Lagrange multipliers to reduce their action to zero. The open- and closed-loop control schemes can be analyzed. The method, referred to as the constrained modal space optimal control (CMSOC), is illustrated in the examples of gantry crane operations.

  3. Search for the optimal size of printed circuit boards for mechanical structures for electronic equipment

    Directory of Open Access Journals (Sweden)

    Yefimenko A. A.

    2014-12-01

    Full Text Available The authors present a method, an algorithm and a program, designed to determine the optimal size of printed circuit boards (PCB of mechanical structures and different kinds of electronic equipment. The PCB filling factor is taken as an optimization criterion. The method allows one to quickly determine the dependence of the filling factor on the size of the PCB for various components.

  4. Effect of synergism in the mechanics of multilayer designs. 2. synthesis of optimal acoustic systems

    Science.gov (United States)

    Urzhumtsev, Yu. S.; Babe, G. D.; Gusev, E. L.

    1985-07-01

    Use of the synergism effect in the mechanics of inhomogeneous systems, and algorithms constructed on the basis of the theory of optimal control makes it possible to synthesize multilayer designs that are optimum in terms of weight capacity, thermal stability, sound conduction, and sound insulation. The proposed approach to solution of the problem of the optimal design of multilayer acoustic systems makes it possible firstly to develop a rather effective method on the basis of this approach; this method reduces to a solution that is optimal in terms of the physical parameters of the layer materials, the layer thicknesses, and the number of layers; and, secondly, to establish a number of qualitative attributes of the parameters of optimal multilayer structures. This approach is also promising for the development of methods for the optimization of multilayer foundations and systems that dampen vibrational loadings, earthquake-resistant designs, and armor protection.

  5. Mechanisms of Selenium Uptake, Translocation and Chemical Speciation Transformation in Plants%植物对硒的吸收转运和形态转化机制

    Institute of Scientific and Technical Information of China (English)

    王晓芳; 陈思杨; 罗章; 黄青青; 乔玉辉; 孙宏杰; 李花粉

    2014-01-01

    阐述了植物对不同形态硒的吸收、转运和形态转化机制。植物主要吸收水溶性硒,包括部分有机硒、硒酸盐和亚硒酸盐。多数研究表明植物对硒酸盐的主动吸收是通过高亲和力的硫酸盐转运子完成,最近的研究表明磷酸盐可以调节亚硒酸盐的吸收,磷酸盐转运子在亚硒酸盐的主动吸收过程中有重要作用;植物吸收的硒酸盐很快从根部转移到地上部,在叶片中被还原成亚硒酸盐,进而转化为有机硒化物进入其他组织;而亚硒酸盐及其代谢产物主要积累在根部,极少转移到地上部。进入植物体中的硒转化为含硒氨基酸和硒蛋白参与植物的代谢。%In this review, we summarized the uptake, translocation and metabolism mechanisms of selenium(Se)in plants. Water-soluble Se, including selenate, selenite and some organic selenium, was the predominant form taken up by plants. The active uptake of selenate in plant could be mediated by high affinity sulfate transporters. The mechanism of selenite uptake was not well understood, however, recent studies suggested that selenite uptake was probably mediated by Pi transporters. The translocation of Se from root to shoot was dependent on the form of Se supplied. The selenate taken up by plants was readily translocated to the shoots and reduced to selenite in leaves, then convert-ed to organic Se compound. By contrast, most of the selenite taken up by plants in the roots and only a small fraction was translocated to the shoots. Se could be assimilated to seleno amino acids or selenoprotein after plant uptake, and then involved in the metabolism of plants.

  6. Portfolio optimization problem with nonidentical variances of asset returns using statistical mechanical informatics

    Science.gov (United States)

    Shinzato, Takashi

    2016-12-01

    The portfolio optimization problem in which the variances of the return rates of assets are not identical is analyzed in this paper using the methodology of statistical mechanical informatics, specifically, replica analysis. We defined two characteristic quantities of an optimal portfolio, namely, minimal investment risk and investment concentration, in order to solve the portfolio optimization problem and analytically determined their asymptotical behaviors using replica analysis. Numerical experiments were also performed, and a comparison between the results of our simulation and those obtained via replica analysis validated our proposed method.

  7. Mechanism of riboflavin uptake by cultured human retinal pigment epithelial ARPE-19 cells: possible regulation by an intracellular Ca2+-calmodulin-mediated pathway

    OpenAIRE

    Said, Hamid M.; Wang, S.L.; Ma, T Y

    2005-01-01

    In mammalian cells (including those of the ocular system), the water-soluble vitamin B-2 (riboflavin, RF) assumes an essential role in a variety of metabolic reactions and is critical for normal cellular functions, growth and development. Cells of the human retinal pigment epithelium (hRPE) play an important role in providing a sufficient supply of RF to the retina, but nothing is known about the mechanism of the vitamin uptake by these cells and its regulation. Our aim in the present study w...

  8. Design and multi-objective optimization for a broad self-amplified 2-DOF monolithic mechanism

    Indian Academy of Sciences (India)

    THANH-PHONG DAO; SHYH-CHOUR HUANG

    2017-09-01

    This paper proposes a structural design and multi-objective optimization of a two-degree-of-freedom (DOF) monolithic mechanism. The mechanism is designed based on compliant mechanism with flexure hinge and is compact in size (126 mm by 107 mm). Unlike traditional one-lever mechanisms, a new doublelever mechanism is developed to increase the working travel amplification ratio of the monolithic mechanism. The ideal amplification ratio, the working travel, the statics and the dynamics of the mechanism are taken into consideration. The effects of design variables on the output responses such as the displacement and first natural frequency are investigated via finite-element analysis based on response surface methodology. The fuzzy-logicbased Taguchi method is then used to simultaneously optimize the displacement and the first natural frequency. Experimental validations are conducted to verify the optimal results, which are compared to those of the original design. On using a finite-element method, the validation results indicated that the displacement and frequency are enhanced by up to 12.47% and 33.27%, respectively, over those of the original design. The experiment results are in a good agreement with the simulations. It also revealed that the developed fuzzy-logic-based Taguchi method is an effectively systematic reasoning approach for optimizing the multiple quality characteristics of compliant mechanisms. It was noted that the working travel/displacement of the double-levermechanism is much larger than that of the traditional one-lever mechanism. It leads to the conclusion that the proposed mechanism has good performances for manipulations and positioning systems.

  9. Design of optimal fast scanning trajectory for the mechanical scanner of measurement instruments.

    Science.gov (United States)

    Ju, Bing-Feng; Bai, Xiaolong; Chen, Jian; Ge, Yaozheng

    2014-01-01

    This paper focuses on the design of the optimal scanning mode for the family of scanning probe microscopes. Based on different values of the maximum acceleration (deceleration) rate and maximum speed of X- and Y- axes of the mechanical scanner encountered in practice due to different mechanical design and loads, the design procedure of the optimal fast scanning mode is presented, which is found to be sensitive to the specific parameters of the scanning motion. By utilizing the simultaneous motion of the two axes, the fast raster scanning mode proposed can improve the scanning efficiency by 29% when comparing with the conventional raster (CR) scanning mode, if the scanning speeds of both axes are identical. In addition, the optimal fast mode provided by us has no effects on the image accuracy such as image degradation, image distortion when the efficiency is evaluated. No further difficulties are introduced to the control of the mechanical scanner and the data acquisition process. This optimal scanning mode is useful when the response time of the probe is very fast (such as ultrasonic probe in scanning acoustic microscope (SAM)), and the main limitations are due to the mechanical scanner. By applying different loads for both axes, the experiments with different scanning areas and scanning modes are conducted in a self-developed SAM. Experimental results coincide with the theoretical analysis and confirm the validation of our proposed optimal fast scanning mode and its superiority over the CR scanning mode.

  10. Bone marrow mesenchymal stem cell therapy in ischemic stroke: mechanisms of action and treatment optimization strategies

    Directory of Open Access Journals (Sweden)

    Guihong Li

    2016-01-01

    Full Text Available Animal and clinical studies have confirmed the therapeutic effect of bone marrow mesenchymal stem cells on cerebral ischemia, but their mechanisms of action remain poorly understood. Here, we summarize the transplantation approaches, directional migration, differentiation, replacement, neural circuit reconstruction, angiogenesis, neurotrophic factor secretion, apoptosis, immunomodulation, multiple mechanisms of action, and optimization strategies for bone marrow mesenchymal stem cells in the treatment of ischemic stroke. We also explore the safety of bone marrow mesenchymal stem cell transplantation and conclude that bone marrow mesenchymal stem cell transplantation is an important direction for future treatment of cerebral ischemia. Determining the optimal timing and dose for the transplantation are important directions for future research.

  11. Optimization of sequences in CDMA systems: a statistical-mechanics approach

    CERN Document Server

    Kitagawa, Koichiro

    2008-01-01

    Statistical mechanics approach is useful not only in analyzing macroscopic system performance of wireless communication systems, but also in discussing design problems of wireless communication systems. In this paper, we discuss a design problem of spreading sequences in code-division multiple-access (CDMA) systems, as an example demonstrating the usefulness of statistical mechanics approach. We analyze, via replica method, the average mutual information between inputs and outputs of a randomly-spread CDMA channel, and discuss the optimization problem with the average mutual information as a measure of optimization. It has been shown that the average mutual information is maximized by orthogonally-invariant random Welch bound equality (WBE) spreading sequences.

  12. The application of artificial intelligence in the optimal design of mechanical systems

    Science.gov (United States)

    Poteralski, A.; Szczepanik, M.

    2016-11-01

    The paper is devoted to new computational techniques in mechanical optimization where one tries to study, model, analyze and optimize very complex phenomena, for which more precise scientific tools of the past were incapable of giving low cost and complete solution. Soft computing methods differ from conventional (hard) computing in that, unlike hard computing, they are tolerant of imprecision, uncertainty, partial truth and approximation. The paper deals with an application of the bio-inspired methods, like the evolutionary algorithms (EA), the artificial immune systems (AIS) and the particle swarm optimizers (PSO) to optimization problems. Structures considered in this work are analyzed by the finite element method (FEM), the boundary element method (BEM) and by the method of fundamental solutions (MFS). The bio-inspired methods are applied to optimize shape, topology and material properties of 2D, 3D and coupled 2D/3D structures, to optimize the termomechanical structures, to optimize parameters of composites structures modeled by the FEM, to optimize the elastic vibrating systems to identify the material constants for piezoelectric materials modeled by the BEM and to identify parameters in acoustics problem modeled by the MFS.

  13. Optimization of mechanical draft counter flow wet-cooling tower using artificial bee colony algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Rao, R.V., E-mail: ravipudirao@gmail.co [S.V. National Institute of Technology, Surat, Gujarat State 395 007 (India); Patel, V.K. [S.V. National Institute of Technology, Surat, Gujarat State 395 007 (India)

    2011-07-15

    Research highlights: {yields} ABC algorithm is used for optimization of counter flow wet-cooling tower. {yields} Minimizing the total annual cost for specific heat duty is the objective function. {yields} Six examples are presented to demonstrate the effectiveness of the proposed algorithm. {yields} The results are compared with the results of GAMS optimization package. {yields} The ABC algorithm can be modified to suit optimization of other thermal systems. -- Abstract: This study explores the use of artificial bee colony (ABC) algorithm for design optimization of mechanical draft counter flow wet-cooling tower. Minimizing the total annual cost for specific heat duty requirement is considered as objective function. Three design variables such as water to air mass ratio, mass velocity of water and mass velocity of air are considered for optimization. Evaluations of the cooling tower geometry and performances are based on an adaptive version of Merkel's method. Temperature and enthalpy constraints are included in the optimization procedure. Six examples are presented to demonstrate the effectiveness and accuracy of the proposed algorithm. The results of optimization using ABC are validated by comparing with those obtained by using GAMS optimization package. The effect of variation of ABC parameters on the convergence and optimum value of the objective function has also been presented.

  14. CONTINUUM TOPOLOGY OPTIMIZATION FOR MONOLITHIC COMPLIANT MECHANISMS OF MICRO-ACTUATORS

    Institute of Scientific and Technical Information of China (English)

    Luo Zhen; Du Yixian; Chen Liping; Yang Jingzhou; Karim Abdel-Malek

    2006-01-01

    A multi-objective scheme for structural topology optimization of distributed compliant mechanisms of micro-actuators in MEMS condition is presented in this work, in which mechanical flexibility and structural stiffness are both considered as objective functions. The compliant micro-mechanism developed in this way can not only provide sufficient output work but also have sufficient rigidity to resist reaction forces and maintain its shape when holding the work-piece. A density filtering approach is also proposed to eliminate numerical instabilities such as checkerboards, mesh-dependency and one-node connected hinges occurring in resulting mechanisms. SIMP is used as the interpolation scheme to indicate the dependence of material modulus on element-regularized densities. The sequential convex programming method, such as the methodof moving asymptotes (MMA), is used to solve the optimization problem. The validation of the presented methodologies is demonstrated by a typical numerical example.

  15. Optimization in Friction Stir Welding - With Emphasis on Thermo-mechanical Aspects

    DEFF Research Database (Denmark)

    Tutum, Cem Celal

    This book deals with the challenging multidisciplinary task of combining variant thermal and thermo-mechanical simulations for the manufacturing process of friction stir welding (FSW) with numerical optimization techniques in the search for optimal process parameters. The FSW process is character......This book deals with the challenging multidisciplinary task of combining variant thermal and thermo-mechanical simulations for the manufacturing process of friction stir welding (FSW) with numerical optimization techniques in the search for optimal process parameters. The FSW process...... is characterized by multiphysics involving solid material flow, heat transfer, thermal softening, recrystallization and the formation of residual stresses. Initially, the thermal models were addressed since they in essence constitute the basis of all other models of FSW. Following this, several integrated thermo...... combined with classical single-objective and evolutionary multi-objective optimization algorithms (i.e. SQP and NSGA-II), to find the optimum process parameters (heat input, rotational and traverse welding speeds) that would result in favorable thermo-mechanical conditions for the process....

  16. Integrated opto-mechanical optimization analysis of large-aperture primary mirror's support position

    Science.gov (United States)

    Ke, Ding; Bo, Qi; Jiang, Bian

    2016-10-01

    Large mirror's support position plays a very important role in optical system's wave-front error. This paper took a Φ1.2m diameter primary mirror as an example and introduced the method of integrated opto-mechanical optimization analysis, then structure's parametric model in Proe, finite element's parametric model in Patran, structure analysis in Nastran and opto-mechanical coupling analysis in Sigfit were integrated as a fully automatic process in Isight by use of command streams and result documents produced by these soft wares. After the process was established and verified, automatic gradient searches of primary mirror's optimal support position were conducted using optimizer embedded in Isight. The optimization objective is the minimum of surface error's RMS and the optimization variables are support positions. New searches can easily be conducted repeatedly after mirror's model is modified in the structure parameter document. Because of the search process is fully automatic, manpower and computing time are greatly saved. This example also provides a good reference for problems in opto-mechanical fields.

  17. Design of articulated mechanisms with a degree of freedom constraint using global optimization

    DEFF Research Database (Denmark)

    Kawamoto, Atsushi; Stolpe, Mathias

    2004-01-01

    This paper deals with design of articulated mechanisms using a truss ground structure representation. The considered mechanism design problem is to maximize the output displacement for a given input force by choosing a prescribed number of truss elements out of all the available elements, so...... displacements. The problem is formulated as a non-convex mixed integer problem and solved using a convergent deterministic global optimization method based on branch and bound with convex relaxations....

  18. Solid lipid nanoparticles (SLN) of Efavirenz as lymph targeting drug delivery system: Elucidation of mechanism of uptake using chylomicron flow blocking approach.

    Science.gov (United States)

    Makwana, Vivek; Jain, Rashmi; Patel, Komal; Nivsarkar, Manish; Joshi, Amita

    2015-11-10

    The aim of the present work was to develop a lymph targeted SLN formulation of antiretroviral (ARV) drug and to have an understanding of its underlying mechanism of uptake by the lymphatics. The lymphatics are the inaccessible reservoirs of HIV in human body. Efavirenz (EFV) is a BCS class II, ARV drug that undergoes extensive first pass metabolism. The EFV SLN formulation was prepared using Gelucire 44/14, Compritol 888 ATO, Lipoid S 75 and Poloxamer 188 by hot homogenization technique followed by ultrasonication method, with mean particle size of 168 nm, polydispersity index (PDI) SLN. In vitro drug release was found to be prolonged and biphasic in PBS pH 6.8. There was no significant change in the mean particle size, PDI, zeta potential and entrapment efficiency of EFV SLN after storage at 30 ± 2°C/60 ± 5%RH for two months. The results from lymphatic transport and tissue distribution study indicate that a significant part of the EFV had by-passed portal system and was recovered in the lymph via chylomicron uptake mechanism. Reduction in the amount (44.70%) of the EFV reaching to liver indicates that major amount of EFV bypasses the liver and thereby, enhances the oral bioavailability of the EFV. A significant amount of EFV was found in spleen, a major lymphatic organ. EFV SLN seems to have potential to target the ARV to lymphatics for the better management of HIV.

  19. Statistical-mechanics-inspired optimization of sensor field configuration for detection of mobile targets.

    Science.gov (United States)

    Mukherjee, Kushal; Gupta, Shalabh; Ray, Asok; Wettergren, Thomas A

    2011-06-01

    This paper presents a statistical-mechanics-inspired procedure for optimization of the sensor field configuration to detect mobile targets. The key idea is to capture the low-dimensional behavior of the sensor field configurations across the Pareto front in a multiobjective scenario for optimal sensor deployment, where the nondominated points are concentrated within a small region of the large-dimensional decision space. The sensor distribution is constructed using location-dependent energy-like functions and intensive temperature-like parameters in the sense of statistical mechanics. This low-dimensional representation is shown to permit rapid optimization of the sensor field distribution on a high-fidelity simulation test bed of distributed sensor networks.

  20. OPTIMAL DESIGNS AND CAPABILITY LIMITS OF SINGLE ROLLER-TO-CAM INDEXING MECHANISMS FOR THREE DWELLS

    Directory of Open Access Journals (Sweden)

    DR. K. S. TRIPATHI

    2010-12-01

    Full Text Available This paper aims to investigate the continuous contact single roller-to-cam indexing mechanism for optimal designs and capability limits, based on generic transmission and curvature constraint for three dwell periods. First of all, the paper determines the solutions of the problems associated with multiple dwells and then develops optimal designs for three maximum extent dwell periods with equal indexing angles with curvature and transmission constraints. Next, stipulating that the three dwell periods should be equal; iteration is done. This gives optimal designs for three equal maximized dwells with equal indexing periods with curvature and transmission constraints. Final information in the form of capability limits will be very helpful to those who search for various alternative indexing mechanisms for several applications of automatic and packaging industries.

  1. Optimization of the Mechanical and Electrical Performance of a Thermoelectric Module

    DEFF Research Database (Denmark)

    Sarhadi, Ali; Bjørk, Rasmus; Pryds, Nini

    2015-01-01

    Finite element (FE) simulation of a thermoelectric (TE) module was conducted to optimize its geometrical dimensions in terms of mechanical reliability and performance. The TE module consisted of bismuth telluride, nand p-type legs. The geometrical dimensions of the module, i.e. leg length and leg...

  2. Investigating a potential mechanism of Cd resistance in Chironomus riparius larvae using kinetic analysis of calcium and cadmium uptake

    Energy Technology Data Exchange (ETDEWEB)

    Gillis, Patricia L. [Department of Biology, McMaster University, Hamilton, ON, L8S-4K1 (Canada)], E-mail: patty.gillis@ec.gc.ca; Wood, Chris M. [Department of Biology, McMaster University, Hamilton, ON, L8S-4K1 (Canada)

    2008-09-17

    The uptake kinetics of waterborne Ca and Cd, both independently and in combination, were examined in C. riparius larvae, which are extremely Cd tolerant. Larvae exposed to Ca (100-2500 {mu}mol L{sup -1}), exhibited classic Michaelis-Menten saturation kinetics for Ca influx, measured using {sup 45}Ca as a radio-tracer. The maximum rate of Ca influx (J{sub max}{sup Ca}) was 0.39 {mu}mol g{sup -1} h{sup -1}, and the Ca concentration where the carrier reached half saturation (K{sub M}{sup Ca}) was 289 {mu}mol L{sup -1}. Cd influx was measured using {sup 109}Cd as a radio-tracer in larvae exposed to Cd (0-1400 {mu}mol L{sup -1}) while the Ca concentration was set to the K{sub M}{sup Ca}. This revealed a J{sub max}{sup Cd} (2.26 {mu}mol g{sup -1} h{sup -1}) which was nearly 6-fold higher that of Ca. This unusually high capacity for Cd uptake is in accordance with the huge tissue Cd burdens that chironomid larvae are able to accumulate during high level exposures. The apparent K{sub M}{sup Cd} (1133 {mu}mol Cd L{sup -1}), when recalculated to account for the background Ca level, was still high (567 {mu}mol Cd L{sup -1}), suggesting that this organism has a low affinity for Cd relative to most aquatic animals, indeed lower or comparable to its affinity for Ca. In consequence, even well above environmentally relevant Cd exposures, C. riparius does not accumulate Cd at the expense of Ca, thereby avoiding internal hypocalcaemia, in contrast to most other organisms which are much more sensitive to Cd. However, Ca influx was significantly reduced when 1200 {mu}mol Cd L{sup -1} was added to Ca exposures (96-2410 {mu}mol L{sup -1}). Michaelis-Menten analysis revealed a similar J{sub max}{sup Ca} in Cd-exposed and control larvae (i.e. exposed only to Ca), but that the apparent K{sub M}{sup Ca} was many-fold higher in larvae which were simultaneously exposed to Ca and Cd. Conversely, increasing Ca concentrations (96-2410 {mu}mol L{sup -1}) progressively inhibited Cd uptake from a

  3. System Topology Optimization - An Approach to System Design of Electro-Hydraulic-Mechanical Systems

    DEFF Research Database (Denmark)

    Andersen, T. O.; Hansen, M. R.; Conrad, Finn

    2003-01-01

    design the procedure attempts to find the optimal topology and the related parameters. The topology considerations comprise the type of hydraulic pump, the employment of knee linkages or not as well as the type of hydraulic actuators. The design variables also include the signals to the proportional......The current paper presents an approach to system design of combined electro-hydraulic-mechanical systems. The approach is based on the concurrent handling of the topology as well as the design parameters of the mechanical, hydraulic and controller sub- systems, respectively. Based on an initial...... valve in a number of predefined load cases as well as the hydraulic and mechanical parameters....

  4. OPTIMIZATION OF CORONARY STENT STRUCTURE DESIGN FOR MAXIMIZING THE ANTI-COMPRESSION MECHANICAL PROPERTY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Excellent mechanical property of the anti-compression or high collapse pressure has become an essential feature of new coronary stents. How to determine the design parameters of stent becomes the key to improve the stent quality. An integrated approach using radial basis function neural network (RBFNN) and genetic algorithm (GA) for the optimization of anti-compression mechanical property of stent is presented in this paper. First, finite element simulation and RBFNN are used to map the complex non-linear relationship between the collapse pressure and stent design parameters. Then GA is employed with the fitness function based on an RBFNN model for arriving at optimum configuration of the stent by maximizing the collapse pressure. The results of numerical experiment demonstrate that the combination of RBFNN and GA is an effective approach for the mechanical properties optimization of stent.

  5. Method for the multi-criteria optimization of car wheel suspension mechanisms

    Directory of Open Access Journals (Sweden)

    Catalin Alexandru

    2016-08-01

    Full Text Available The paper deals with a general method for the multi-criteria optimization of the rear wheels suspension mechanisms in terms of kinematic behavior. The suspension mechanism is decomposed in basic binary links, and the kinematic synthesis is separately performed for each of them. The design variables are the global coordinates of the joint locations on the car body (chassis. The disposing of the joints on the wheel carrier were exclusively established by constructive criteria. The design objectives relate to kinematic position parameters of the wheel (displacements of the wheel centre along longitudinal and transversal directions, and modifications of the wheel axis direction, the optimization goal being to minimize these variations during the wheel travel. A computer program for the kinematic study was developed in C++. The application was performed for the wheel suspension mechanism of a race car.

  6. Intracellular trafficking and cellular uptake mechanism of mPEG-PLGA-PLL and mPEG-PLGA-PLL-Gal nanoparticles for targeted delivery to hepatomas.

    Science.gov (United States)

    Liu, Peifeng; Sun, Yanming; Wang, Qi; Sun, Ying; Li, He; Duan, Yourong

    2014-01-01

    The lysosomal escape of nanoparticles is crucial to enhancing their delivery and therapeutic efficiency. Here, we report the cellular uptake mechanism, lysosomal escape, and organelle morphology effect of monomethoxy (polyethylene glycol)-poly (D,L-lactide-co-glycolide)-poly (L-lysine) (mPEG-PLGA-PLL, PEAL) and 4-O-beta-D-Galactopyranosyl-D-gluconic acid (Gal)-modified PEAL (PEAL-Gal) for intracellular delivery to HepG2, Huh7, and PLC hepatoma cells. These results indicate that PEAL is taken up by clathrin-mediated endocytosis of HepG2, Huh7 and PLC cells. For PEAL-Gal, sialic acid receptor-mediated endocytosis and clathrin-mediated endocytosis are the primary uptake pathways in HepG2 cells, respectively, whereas PEAL-Gal is internalized by sag vesicle- and clathrin-mediated endocytosis in Huh7 cells. In the case of PLC cells, clathrin-mediated endocytosis and sialic acid receptor play a primary role in the uptake of PEAL-Gal. TEM results verify that PEAL and PEAL-Gal lead to a different influence on organelle morphology of HepG2, Huh7 and PLC cells. In addition, the results of intracellular distribution reveal that PEAL and PEAL-Gal are less entrapped in the lysosomes of HepG2 and Huh7 cells, demonstrating that they effectively escape from lysosomes and contribute to enhance the efficiency of intracellular delivery and tumor therapy. In vivo tumor targeting image results demonstrate that PEAL-Gal specifically delivers Rhodamine B (Rb) to the tumor tissue of mice with HepG2, Huh7, and PLC hepatomas and remains at a high concentration in tumor tissue until 48 h, properties that will greatly contribute to enhanced antitumor efficiency. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  7. Mechanism Analysis and Parameter Optimization of Mega-Sub-Isolation System

    Directory of Open Access Journals (Sweden)

    Xiangxiu Li

    2016-01-01

    Full Text Available The equation of motion of mega-sub-isolation system is established. The working mechanism of the mega-sub-isolation system is obtained by systematically investigating its dynamic characteristics corresponding to various structural parameters. Considering the number and location of the isolated substructures, a procedure to optimally design the isolator parameters of the mega-sub-isolation system is put forward based on the genetic algorithm with base shear as the optimization objective. The influence of the number and locations of isolated substructures on the control performance of mega-sub-isolation system has also been investigated from the perspective of energy. Results show that, with increase in substructure mass, the working mechanism of the mega-sub-isolation system is changed from tuned vibration absorber and energy dissipation to seismic isolation. The locations of the isolated substructures have little influence on the optimal frequency ratio but have great influence on the optimal damping ratio, while the number of isolated substructures shows great impact on both the optimal frequency ratio and damping ratio. When the number of the isolated substructures is determined, the higher the isolated substructures, the more the energy that will be consumed by the isolation devices, and with the increase of the number of isolated substructures, the better control performance can be achieved.

  8. An optimized ensemble local mean decomposition method for fault detection of mechanical components

    Science.gov (United States)

    Zhang, Chao; Li, Zhixiong; Hu, Chao; Chen, Shuai; Wang, Jianguo; Zhang, Xiaogang

    2017-03-01

    Mechanical transmission systems have been widely adopted in most of industrial applications, and issues related to the maintenance of these systems have attracted considerable attention in the past few decades. The recently developed ensemble local mean decomposition (ELMD) method shows satisfactory performance in fault detection of mechanical components for preventing catastrophic failures and reducing maintenance costs. However, the performance of ELMD often heavily depends on proper selection of its model parameters. To this end, this paper proposes an optimized ensemble local mean decomposition (OELMD) method to determinate an optimum set of ELMD parameters for vibration signal analysis. In OELMD, an error index termed the relative root-mean-square error (Relative RMSE) is used to evaluate the decomposition performance of ELMD with a certain amplitude of the added white noise. Once a maximum Relative RMSE, corresponding to an optimal noise amplitude, is determined, OELMD then identifies optimal noise bandwidth and ensemble number based on the Relative RMSE and signal-to-noise ratio (SNR), respectively. Thus, all three critical parameters of ELMD (i.e. noise amplitude and bandwidth, and ensemble number) are optimized by OELMD. The effectiveness of OELMD was evaluated using experimental vibration signals measured from three different mechanical components (i.e. the rolling bearing, gear and diesel engine) under faulty operation conditions.

  9. Convergent evolution of mechanically optimal locomotion in aquatic invertebrates and vertebrates.

    Directory of Open Access Journals (Sweden)

    Rahul Bale

    2015-04-01

    Full Text Available Examples of animals evolving similar traits despite the absence of that trait in the last common ancestor, such as the wing and camera-type lens eye in vertebrates and invertebrates, are called cases of convergent evolution. Instances of convergent evolution of locomotory patterns that quantitatively agree with the mechanically optimal solution are very rare. Here, we show that, with respect to a very diverse group of aquatic animals, a mechanically optimal method of swimming with elongated fins has evolved independently at least eight times in both vertebrate and invertebrate swimmers across three different phyla. Specifically, if we take the length of an undulation along an animal's fin during swimming and divide it by the mean amplitude of undulations along the fin length, the result is consistently around twenty. We call this value the optimal specific wavelength (OSW. We show that the OSW maximizes the force generated by the body, which also maximizes swimming speed. We hypothesize a mechanical basis for this optimality and suggest reasons for its repeated emergence through evolution.

  10. Convergent evolution of mechanically optimal locomotion in aquatic invertebrates and vertebrates.

    Science.gov (United States)

    Bale, Rahul; Neveln, Izaak D; Bhalla, Amneet Pal Singh; MacIver, Malcolm A; Patankar, Neelesh A

    2015-04-01

    Examples of animals evolving similar traits despite the absence of that trait in the last common ancestor, such as the wing and camera-type lens eye in vertebrates and invertebrates, are called cases of convergent evolution. Instances of convergent evolution of locomotory patterns that quantitatively agree with the mechanically optimal solution are very rare. Here, we show that, with respect to a very diverse group of aquatic animals, a mechanically optimal method of swimming with elongated fins has evolved independently at least eight times in both vertebrate and invertebrate swimmers across three different phyla. Specifically, if we take the length of an undulation along an animal's fin during swimming and divide it by the mean amplitude of undulations along the fin length, the result is consistently around twenty. We call this value the optimal specific wavelength (OSW). We show that the OSW maximizes the force generated by the body, which also maximizes swimming speed. We hypothesize a mechanical basis for this optimality and suggest reasons for its repeated emergence through evolution.

  11. 纳米粒摄取机制的研究进展%Research progress on the cellular uptake mechanism of nanoparticles

    Institute of Scientific and Technical Information of China (English)

    张超; 马桂蕾

    2015-01-01

    With the development of nanotechnology,nanomaterials have great application potential in drug delivery system.Understanding the cellular uptake mechanism of nanoparticles has important scientific significance and application value in understanding life processes in cellular level,mechanisms of drug action and gene therapy,which provides the basis for developing safer and more effective nanosized drug carrier.This review summarizes the latest advancement about cellular uptake mechanisms of nanopatricles.Based on a brief introduction of the endocytic pathway of nanoparticles,influencing factors of endocytosis pathway are discussed,and the common methods used to study nanoparticle endocytosis pathways are also introduced in detail.%随着纳米技术的发展,纳米材料在药物传输领域有着潜在的应用空间.研究细胞对纳米粒的细胞摄取机制,有助于从细胞层次上理解生命体的生理过程和药物的作用机制,掌握细胞治疗的机理;同时也可为构建更加安全有效的纳米药物载体提供依据.综述了纳米粒摄取机制的最新研究进展,在简要介绍纳米粒内吞途径的基础上着重讨论了影响内吞的因素,同时详细介绍了纳米粒内吞途径的常用研究方法.

  12. LEVEL SET METHOD FOR TOPOLOGICAL OPTIMIZATION APPLYING TO STRUCTURE,MECHANISM AND MATERIAL DESIGNS

    Institute of Scientific and Technical Information of China (English)

    Mei Yulin; Wang Xiaoming

    2004-01-01

    Based on a level set model,a topology optimization method has been suggested recently.It uses a level set to express the moving structural boundary,which can flexibly handle complex topological changes.By combining vector level set models with gradient projection technology,the level set method for topological optimization is extended to a topological optimization problem with multi-constraints,multi-materials and multi-load cases.Meanwhile,an appropriate nonlinear speed mapping is established in the tangential space of the active constraints for a fast convergence.Then the method is applied to structure designs,mechanism and material designs by a number of benchmark examples.Finally,in order to further improve computational efficiency and overcome the difficulty that the level set method cannot generate new material interfaces during the optimization process,the topological derivative analysis is incorporated into the level set method for topological optimization,and a topological derivative and level set algorithm for topological optimization is proposed.

  13. Reliability-based optimization of maintenance scheduling of mechanical components under fatigue.

    Science.gov (United States)

    Beaurepaire, P; Valdebenito, M A; Schuëller, G I; Jensen, H A

    2012-05-01

    This study presents the optimization of the maintenance scheduling of mechanical components under fatigue loading. The cracks of damaged structures may be detected during non-destructive inspection and subsequently repaired. Fatigue crack initiation and growth show inherent variability, and as well the outcome of inspection activities. The problem is addressed under the framework of reliability based optimization. The initiation and propagation of fatigue cracks are efficiently modeled using cohesive zone elements. The applicability of the method is demonstrated by a numerical example, which involves a plate with two holes subject to alternating stress.

  14. Statistical Mechanics of On-Line Learning Using Correlated Examples and Its Optimal Scheduling

    Science.gov (United States)

    Fujii, Takashi; Ito, Hidetaka; Miyoshi, Seiji

    2017-08-01

    We theoretically study the generalization capability of on-line learning using several correlated input vectors in each update in a statistical-mechanical manner. We consider a model organized with linear perceptrons with Gaussian noise. First, in a noiseless case, we analytically derive the optimal learning rate as a function of the number of examples used in one update and their correlation. Next, we analytically show that the use of correlated examples is effective if the optimal learning rate is used, even when there is some noise. Furthermore, we propose a novel algorithm that raises the generalization capability by increasing the number of examples used in one update with time.

  15. Workspace Analysis and Optimization of 3-PUU Parallel Mechanism in Medicine Base on Genetic Algorithm.

    Science.gov (United States)

    Hou, Yongchao; Zhao, Yang

    2015-01-01

    A novel 3-PUU parallel robot was put forward, on which kinematic analysis was conducted to obtain its inverse kinematics solution, and on this basis, the limitations of the sliding pair and the Hooke joint on the workspace were analyzed. Moreover, the workspace was solved through the three dimensional limit search method, and then optimization analysis was performed on the workspace of this parallel robot, which laid the foundations for the configuration design and further analysis of the parallel mechanism, with the result indicated that this type of robot was equipped with promising application prospect. In addition that, the workspace after optimization can meet more requirements of patients.

  16. Multifunctional organic–inorganic hybrid nanoparticles and nanosheets based on chitosan derivative and layered double hydroxide: cellular uptake mechanism and application for topical ocular drug delivery

    Science.gov (United States)

    Chi, Huibo; Gu, Yan; Xu, Tingting; Cao, Feng

    2017-01-01

    To study the cellular uptake mechanism of multifunctional organic–inorganic hybrid nanoparticles and nanosheets, new chitosan–glutathione–valine–valine-layered double hydroxide (CG-VV-LDH) nanosheets with active targeting to peptide transporter-1 (PepT-1) were prepared, characterized and further compared with CG-VV-LDH nanoparticles. Both organic–inorganic hybrid nanoparticles and nanosheets showed a sustained release in vitro and prolonged precorneal retention time in vivo, but CG-VV-LDH nanoparticles showed superior permeability in the isolated cornea of rabbits than CG-VV-LDH nanosheets. Furthermore, results of cellular uptake on human corneal epithelial primary cells (HCEpiC) and retinal pigment epithelial (ARPE-19) cells indicated that both clathrin-mediated endocytosis and active transport of PepT-1 are involved in the internalization of CG-VV-LDH nanoparticles and CG-VV-LDH nanosheets. In summary, the CG-VV-LDH nanoparticle may be a promising carrier as a topical ocular drug delivery system for the treatment of ocular diseases of mid-posterior segments, while the CG-VV-LDH nanosheet may be suitable for the treatment of ocular surface diseases. PMID:28280329

  17. Cellular uptake mechanism and comparative evaluation of antineoplastic effects of paclitaxel–cholesterol lipid emulsion on triple-negative and non-triple-negative breast cancer cell lines

    Directory of Open Access Journals (Sweden)

    Ye J

    2016-08-01

    Full Text Available Jun Ye,1,2 Xuejun Xia,1,2 Wujun Dong,1,2 Huazhen Hao,1,2 Luhua Meng,1,2 Yanfang Yang,1,2 Renyun Wang,1,2 Yuanfeng Lyu,3 Yuling Liu1,2 1State Key Laboratory of Bioactive Substance and Function of Natural Medicines, 2Beijing Key Laboratory of Drug Delivery Technology and Novel Formulation, Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 3School of Pharmacy, China Pharmaceutical University, Nanjing, People’s Republic of China Abstract: There is no effective clinical therapy for triple-negative breast cancers (TNBCs, which have high low-density lipoprotein (LDL requirements and express relatively high levels of LDL receptors (LDLRs on their membranes. In our previous study, a novel lipid emulsion based on a paclitaxel–cholesterol complex (PTX-CH Emul was developed, which exhibited improved safety and efficacy for the treatment of TNBC. To date, however, the cellular uptake mechanism and intracellular trafficking of PTX-CH Emul have not been investigated. In order to offer powerful proof for the therapeutic effects of PTX-CH Emul, we systematically studied the cellular uptake mechanism and intracellular trafficking of PTX-CH Emul and made a comparative evaluation of antineoplastic effects on TNBC (MDA-MB-231 and non-TNBC (MCF7 cell lines through in vitro and in vivo experiments. The in vitro antineoplastic effects and in vivo tumor-targeting efficiency of PTX-CH Emul were significantly more enhanced in MDA-MB-231-based models than those in MCF7-based models, which was associated with the more abundant expression profile of LDLR in MDA-MB-231 cells. The results of the cellular uptake mechanism indicated that PTX-CH Emul was internalized into breast cancer cells through the LDLR-mediated internalization pathway via clathrin-coated pits, localized in lysosomes, and then released into the cytoplasm, which was consistent with the internalization pathway and intracellular trafficking of native

  18. Passive Vibration Isolation by Compliant Mechanism Using Topology Optimization with Building Blocks

    Directory of Open Access Journals (Sweden)

    V. Vijayan

    2014-10-01

    Full Text Available Compliant Mechanism has been designed for various types of application to transmit desired force and motion. In this study, we have explored an application of Compliant Mechanism for passive vibration isolation systems, for which compliant isolator is used to cancel undesired disturbance, which results in attenuated output amplitude. The Compliant Mechanism is equipped with isolator, which acts as a transmission of force, in order to control the amount of displacement transmitted from it. Compliant Mechanism also used as passive vibration isolator. Here, introducing compliance into the connection, the transmission of applied forces is reduced at some frequencies, at the expense of increasing transmission at other frequencies. The force transmissibility is numerically identical to the motion transmissibility. In order to find the flexible building blocks for force transmissibility, structural optimization approach is applied. The Structural optimization approach focuses on the determination of the topology, shape and size of the mechanism. Thus approach is used to establish the actuator model of the block and it is validated by commercial Finite Element software. A library of compliant elements is proposed in FlexIn. These blocks are in limited number and the basis is composed of 36 elements. The force transmitted to the rigid foundation through the isolator is reduced to avoid transmission of vibration to other machines. Thus the preliminary results of FEA from ANSYS demonstrate that the compliant mechanism can be effectively used to reduce the amount of force transmitted to the surface.

  19. Optimal Path Design of Geared 5-bar mechanism using Differential Evolution Algorithm

    Directory of Open Access Journals (Sweden)

    Ali Aliniay Saghalaksari

    2016-06-01

    Full Text Available Five-bar linkage mechanisms with two degrees of freedom (DOF are more capable in generating coupler path than four-bar mechanisms with one DOF. The DOF of these mechanisms is reduced to one and they will have constant ratio of binary input when they are equipped by gear. Therefore, besides keeping the simple structure, it is possible to employ them to generate a more accurate path than that generated by four-bar mechanisms using only one input. In this study, using such mechanism for the considered paths, which are used for the comparison purpose, a singleobjective design is performed to optimize the length of mechanism links and revolution ratio of gears by considering the necessary constraints. The error function of square deviation of positions is considered as the objective function and the differential evolution algorithm is utilized in order to solve the considered optimization problems, which are Triangle Curve with 22 Discrete Points and Asteroid Curve with 41 Discrete Points. Compared with the main reference [9], the final results revealed a significant improvement.

  20. Design and optimization of concurrent tolerance in mechanical assemblies using bat algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, L. Ramesh [Christian College of Engineering and Technology, Oddanchatram (India); Padmanaban, K. P. [Kurunji College of Engineering and Technology, Trichy (India); Kumar, S. Ganesh [SSM Institute of Engineering and Technology, Dindigul (India); Balamurugan, C. [Anna University, Chennai (India)

    2016-06-15

    Concurrent designing of tolerance has become a vital concern in product and process development due to the relationship between quality, functionality and product cost. It is one of the well explored areas in combinatorial optimization. In this paper, a recently developed optimization algorithm, called Bat algorithm (BA), is used for optimizing the tolerance based on concurrent objectives to minimize the manufacturing cost, present worth of expected quality loss and quality loss. The mechanical assemblies such as Bevel gear assembly (A), Gear box assembly (B) and Suction union assembly (C) are considered to demonstrate the proposed algorithm. It is found that the BA has produced better results than other methods in initial generations for concurrent tolerance problems.

  1. Optimal Control and higher-order mechanics for systems with symmetries

    CERN Document Server

    Colombo, Leonardo; de Diego, David Martin

    2012-01-01

    In this paper we will develop and design numerical methods for optimal control problems for a class of underactuated Lagrangian mechanical systems where the configuration manifold is a trivial principal bundle . We will construct these geometric integrators using discrete variational calculus, deriving a discrete version of the higher-order Euler-Lagrange equations on trivial principal bundles. The analysis applies to systems subject to higher-order constraints (that is, depending of higher-order derivatives as, for example, the acceleration). Interesting applications as, for instance, a discrete derivation of the Euler-Lagrange equations for higher-order Lagrangians and higher-order reduced Lagrangians, respectively, are shown. We find interesting applications both in the optimal control of an underactuated vehicle and the well-known plate ball problem seen as an optimization problem with nonholonomic constraints .

  2. An Improved Fruit Fly Optimization Algorithm Inspired from Cell Communication Mechanism

    Directory of Open Access Journals (Sweden)

    Chuncai Xiao

    2015-01-01

    Full Text Available Fruit fly optimization algorithm (FOA invented recently is a new swarm intelligence method based on fruit fly’s foraging behaviors and has been shown to be competitive with existing evolutionary algorithms, such as particle swarm optimization (PSO algorithm. However, there are still some disadvantages in the FOA, such as low convergence precision, easily trapped in a local optimum value at the later evolution stage. This paper presents an improved FOA based on the cell communication mechanism (CFOA, by considering the information of the global worst, mean, and best solutions into the search strategy to improve the exploitation. The results from a set of numerical benchmark functions show that the CFOA outperforms the FOA and the PSO in most of the experiments. Further, the CFOA is applied to optimize the controller for preoxidation furnaces in carbon fibers production. Simulation results demonstrate the effectiveness of the CFOA.

  3. The study of mechanism synthesis and optimization for the mechanism of fire-monitor with straight flow channel

    Science.gov (United States)

    Liu, Ping'an; Wang, Xiaoliang

    2017-01-01

    Design of a new fire-monitor through the substitution of the traditional bend flow channel with a straight tube is presented in this paper, in order to deduce the pressure drop when hydraulic fluid goes through the channel, and the serial-parallel structure with a four-bar linkage plus a revolute pair is used so as to realize two rotating degrees of freedom. The type synthesis of mechanism, the dimensional optimization of the four-bar linkage, as well as the design of the oscillating mechanism is delivered in sequence, and the model has also been developed, finally. All the work has achieved the expected results, which has guidance to the redevelopment of fire-monitor with high efficiency and lower energy assumption.

  4. Hybrid Optimization Approach for the Design of Mechanisms Using a New Error Estimator

    Directory of Open Access Journals (Sweden)

    A. Sedano

    2012-01-01

    Full Text Available A hybrid optimization approach for the design of linkages is presented. The method is applied to the dimensional synthesis of mechanism and combines the merits of both stochastic and deterministic optimization. The stochastic optimization approach is based on a real-valued evolutionary algorithm (EA and is used for extensive exploration of the design variable space when searching for the best linkage. The deterministic approach uses a local optimization technique to improve the efficiency by reducing the high CPU time that EA techniques require in this kind of applications. To that end, the deterministic approach is implemented in the evolutionary algorithm in two stages. The first stage is the fitness evaluation where the deterministic approach is used to obtain an effective new error estimator. In the second stage the deterministic approach refines the solution provided by the evolutionary part of the algorithm. The new error estimator enables the evaluation of the different individuals in each generation, avoiding the removal of well-adapted linkages that other methods would not detect. The efficiency, robustness, and accuracy of the proposed method are tested for the design of a mechanism in two examples.

  5. Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism

    Science.gov (United States)

    Zhang, Dan; Wei, Bin

    2017-04-01

    The interactions between stiffness and workspace performances are studied. The stiffness in x, y and z directions as well as the workspace of a 3-UPU mechanism are studied and optimized. The stiffness of the robotic system in every single moveable direction is measured and analyzed, and it is observed that in the case where one tries to make the x and y translational stiffness larger, the z directional stiffness will be reduced, i.e. the x and y translational stiffness contradicts with the one in z direction. Subsequently, the objective functions for the summation of the x and y translational stiffness and z directional stiffness are established and they are being optimized simultaneously. However, we later found that these two objectives are not in the same scale; a normalization of the objectives is thus taken into consideration. Meanwhile, the robotic system's workspace is studied and optimized. Through comparing the stiffness landscape and the workspace volume landscape, it is also observed that the z translational stiffness shows the same changing tendency with the workspace volume's changing tendency while the x and y translational stiffness shows the opposite changing tendency compared to the workspace volume's. Via employing the Pareto front theory and differential evolution, the summation of the x and y translational stiffness and the volume of the workspace are being simultaneously optimized. Finally, the mechanism is employed to synthesize an exercise-walking machine for stroke patients.

  6. Hybridizing artificial bee colony with biogeography-based optimization for constrained mechanical design problems

    Institute of Scientific and Technical Information of China (English)

    蔡绍洪; 龙文; 焦建军

    2015-01-01

    A novel hybrid algorithm named ABC-BBO, which integrates artificial bee colony (ABC) algorithm with biogeography-based optimization (BBO) algorithm, is proposed to solve constrained mechanical design problems. ABC-BBO combined the exploration of ABC algorithm with the exploitation of BBO algorithm effectively, and hence it can generate the promising candidate individuals. The proposed hybrid algorithm speeds up the convergence and improves the algorithm’s performance. Several benchmark test functions and mechanical design problems are applied to verifying the effects of these improvements and it is demonstrated that the performance of this proposed ABC-BBO is superior to or at least highly competitive with other population-based optimization approaches.

  7. Structural Studies of Bacterioferritin B from Pseudomonas aeruginosa Suggest a Gating Mechanism for Iron Uptake via the Ferroxidase Center

    Energy Technology Data Exchange (ETDEWEB)

    Weeratunga, Saroja K.; Lovell, Scott; Yao, Huili; Battaile, Kevin P.; Fischer, Christopher J.; Gee, Casey E.; Rivera, Mario (Kansas); (HWMRI)

    2010-03-16

    solution, suggest that the ferroxidase pore is the dominant entry route for the uptake of iron by Pa BfrB. These findings, which are clearly distinct from those made with Escherichia coli Bfr [Crow, A. C., Lawson, T. L., Lewin, A., Moore, G. R., and Le Brun, N. E. (2009) J. Am. Chem. Soc. 131, 6808-6813], indicate that not all bacterioferritins operate in the same manner.

  8. Fermilab Central Computing Facility: Energy conservation report and mechanical systems design optimization and cost analysis study

    Energy Technology Data Exchange (ETDEWEB)

    Krstulovich, S.F.

    1986-11-12

    This report is developed as part of the Fermilab Central Computing Facility Project Title II Design Documentation Update under the provisions of DOE Document 6430.1, Chapter XIII-21, Section 14, paragraph a. As such, it concentrates primarily on HVAC mechanical systems design optimization and cost analysis and should be considered as a supplement to the Title I Design Report date March 1986 wherein energy related issues are discussed pertaining to building envelope and orientation as well as electrical systems design.

  9. Stress optimization of leaf-spring crossed flexure pivots for an active Gurney flap mechanism

    Science.gov (United States)

    Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

    2015-04-01

    The EU's Green Rotorcraft programme is pursuing the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this `smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. The AGF mechanism selected employs leaf-spring crossed flexure pivots. These provide important advantages over bearings as they are not susceptible to seizing and do not require maintenance (i.e. lubrication or cleaning). A baseline design of this mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. For full validation, a flight test would also be required. However, the severity of the in-flight loading conditions would likely compromise the mechanical integrity of the pivots' leaf-springs in their current form. This paper investigates the scope for stress reduction through three-dimensional shape optimization of the leaf-springs of a generic crossed flexure pivot. To this end, a procedure combining a linear strain energy formulation, a parametric leaf-spring profile definition and a series of optimization algorithms is employed. The resulting optimized leaf-springs are proven to be not only independent of the angular rotation at which the pivot operates, but also linearly scalable to leaf-springs of any length, minimum thickness and width. Validated using non-linear finite element analysis, the results show very significant stress reductions relative to pivots with constant cross section leaf-springs, of up to as much as 30% for the specific pivot configuration employed in the AGF mechanism. It is concluded that shape optimization offers great potential for reducing stress in crossed flexure pivots and, consequently, for extending their fatigue life and/or rotational range.

  10. Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms.

    Science.gov (United States)

    Niu, Shuli; Luo, Yiqi; Fei, Shenfeng; Yuan, Wenping; Schimel, David; Law, Beverly E; Ammann, Christof; Arain, M Altaf; Arneth, Almut; Aubinet, Marc; Barr, Alan; Beringer, Jason; Bernhofer, Christian; Black, T Andrew; Buchmann, Nina; Cescatti, Alessandro; Chen, Jiquan; Davis, Kenneth J; Dellwik, Ebba; Desai, Ankur R; Etzold, Sophia; Francois, Louis; Gianelle, Damiano; Gielen, Bert; Goldstein, Allen; Groenendijk, Margriet; Gu, Lianhong; Hanan, Niall; Helfter, Carole; Hirano, Takashi; Hollinger, David Y; Jones, Mike B; Kiely, Gerard; Kolb, Thomas E; Kutsch, Werner L; Lafleur, Peter; Lawrence, David M; Li, Linghao; Lindroth, Anders; Litvak, Marcy; Loustau, Denis; Lund, Magnus; Marek, Michal; Martin, Timothy A; Matteucci, Giorgio; Migliavacca, Mirco; Montagnani, Leonardo; Moors, Eddy; Munger, J William; Noormets, Asko; Oechel, Walter; Olejnik, Janusz; Kyaw Tha Paw U; Pilegaard, Kim; Rambal, Serge; Raschi, Antonio; Scott, Russell L; Seufert, Günther; Spano, Donatella; Stoy, Paul; Sutton, Mark A; Varlagin, Andrej; Vesala, Timo; Weng, Ensheng; Wohlfahrt, Georg; Yang, Bai; Zhang, Zhongda; Zhou, Xuhui

    2012-05-01

    • It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem-climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.

  11. 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%.

  12. Soft-start mechanism with coefficients Ki optimization for DC-DC power converters

    Science.gov (United States)

    Wang, Qian; Hu, Jiajun; Chen, Houpeng; Li, Xi; Fan, Xi; Miao, Jie; Song, Zhitang

    2016-10-01

    This paper presents a fully digital-control soft start mechanism with coefficients Ki optimization for DC-DC power converters. During the soft start phase, a ladder reference voltage steps up gradually to make inductor current ramp up smoothly and overshoot voltage is minimized with the proposed coefficients Ki distribution. Simulation results show that massive inductor current can be well avoided during the soft start process with the proposed soft start mechanism, which only occupies a chip area of 300um×120um.

  13. Adjoint-based optimization of mechanical performance in polycrystalline materials and structures through texture control

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Grace [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brown, Judith Alice [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bishop, Joseph E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-08-01

    The texture of a polycrystalline material refers to the preferred orientation of the grains within the material. In metallic materials, texture can significantly affect the mechanical properties such as elastic moduli, yield stress, strain hardening, and fracture toughness. Recent advances in additive manufacturing of metallic materials offer the possibility in the not too distant future of controlling the spatial variation of texture. In this work, we investigate the advantages, in terms of mechanical performance, of allowing the texture to vary spatially. We use an adjoint-based gradient optimization algorithm within a finite element solver (COMSOL) to optimize several engineering quantities of interest in a simple structure (hole in a plate) and loading (uniaxial tension) condition. As a first step to general texture optimization, we consider the idealized case of a pure fiber texture in which the homogenized properties are transversely isotropic. In this special case, the only spatially varying design variables are the three Euler angles that prescribe the orientation of the homogenized material at each point within the structure. This work paves a new way to design metallic materials for tunable mechanical properties at the microstructure level.

  14. Optimization of Centrifugal Pump Characteristic Dimensions for Mechanical Circulatory Support Devices.

    Science.gov (United States)

    Korakianitis, Theodosios; Rezaienia, Mohammad A; Paul, Gordon M; Rahideh, Akbar; Rothman, Martin T; Mozafari, Sahand

    2016-01-01

    The application of artificial mechanical pumps as heart assist devices impose power and size limitations on the pumping mechanism, and therefore requires careful optimization of pump characteristics. Typically new pumps are designed by relying on the performance of other previously designed pumps of known performance using concepts of fluid dynamic similarity. Such data are readily available for industrial pumps, which operate in Reynolds numbers region of 10. Heart assist pumps operate in Reynolds numbers of 10. There are few data available for the design of centrifugal pumps in this characteristic range. This article develops specific speed versus specific diameter graphs suitable for the design and optimization of these smaller centrifugal pumps concentrating in dimensions suitable for ventricular assist devices (VADs) and mechanical circulatory support (MCS) devices. A combination of experimental and numerical techniques was used to measure and analyze the performance of 100 optimized pumps designed for this application. The data are presented in the traditional Cordier diagram of nondimensional specific speed versus specific diameter. Using these data, nine efficient designs were selected to be manufactured and tested in different operating conditions of flow, pressure, and rotational speed. The nondimensional results presented in this article enable preliminary design of centrifugal pumps for VADs and MCS devices.

  15. Multiobjective Optimization of Steering Mechanism for Rotary Steering System Using Modified NSGA-II and Fuzzy Set Theory

    Directory of Open Access Journals (Sweden)

    Hongtao Li

    2015-01-01

    Full Text Available Due to the complicated design process of gear train, optimization is a significant approach to improve design efficiency. However, the design of gear train is a complex multiobjective optimization with mixed continuous-discrete variables under numerous nonlinear constraints, and conventional optimization algorithms are not suitable to deal with such optimization problems. In this paper, based on the established dynamic model of steering mechanism for rotary steering system, the key component of which is a planetary gear set with teeth number difference, the optimization problem of steering mechanism is formulated to achieve minimum dynamic responses and outer diameter by optimizing structural parameters under geometric, kinematic, and strength constraints. An optimization procedure based on modified NSGA-II by incorporating dynamic crowding distance strategies and fuzzy set theory is applied to the multiobjective optimization. For comparative purpose, NSGA-II is also employed to obtain Pareto optimal set, and dynamic responses of original and optimized designs are compared. The results show the optimized design has better dynamic responses with minimum outer diameter and the response decay decreases faster. The optimization procedure is feasible to the design of gear train, and this study can provide guidance for designer at the preliminary design phase of mechanical structures with gear train.

  16. An investigation of silver electrodeposition from ionic liquids: Influence of atmospheric water uptake on the silver electrodeposition mechanism and film morphology

    Energy Technology Data Exchange (ETDEWEB)

    Basile, Andrew [School of Applied Sciences, RMIT University, G.P.O. Box 2476V, Melbourne, Victoria 3001 (Australia); CSIRO Energy Technology, Clayton, Victoria 3169 (Australia); Bhatt, Anand I., E-mail: anand.bhatt@csiro.a [CSIRO Energy Technology, Clayton, Victoria 3169 (Australia); O' Mullane, Anthony P., E-mail: anthony.omullane@rmit.edu.a [School of Applied Sciences, RMIT University, G.P.O. Box 2476V, Melbourne, Victoria 3001 (Australia); Bhargava, Suresh K. [School of Applied Sciences, RMIT University, G.P.O. Box 2476V, Melbourne, Victoria 3001 (Australia)

    2011-02-28

    The electrodeposition of silver from two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF{sub 4}]) and N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ([C{sub 4}mPyr][TFSI]), and an aqueous KNO{sub 3} solution on a glassy carbon electrode was undertaken. It was found by cyclic voltammetry that the electrodeposition of silver proceeds through nucleation-growth kinetics. Analysis of chronoamperometric data indicated that the nucleation-growth mechanism is instantaneous at all potentials in the case of [BMIm][BF{sub 4}]and [C{sub 4}mPyr][TFSI], and instantaneous at low overpotentials tending to progressive at high overpotentials for KNO{sub 3}. Significantly, under ambient conditions, the silver electrodeposition mechanism changes to progressive nucleation and growth in [C{sub 4}mPyr][TFSI], which is attributed to the uptake of atmospheric water in the IL. It was found that these differences in the growth mechanism impact significantly on the morphology of the resultant electrodeposit which is characterised ex situ by scanning electron microscopy and X-ray diffraction.

  17. Heterogeneity in the Attachment and Uptake Mechanisms of the Legionnaires’ Disease Bacterium, Legionella pneumophila, by Protozoan Hosts

    OpenAIRE

    Harb, Omar S.; Venkataraman, Chandrasekar; Haack, Bradley J.; Gao, Lian-Yong; Kwaik, Yousef Abu

    1998-01-01

    Invasion and intracellular replication of Legionella pneumophila within protozoa in the environment plays a major role in the transmission of Legionnaires’ disease. Intracellular replication of L. pneumophila within protozoa occurs in a rough endoplasmic reticulum (RER)-surrounded phagosome (Y. Abu Kwaik, Appl. Environ. Microbiol. 62:2022–2028, 1996). Since the subsequent fate of many intracellular pathogens is determined by the route of entry, we compared the mechanisms of attachment and sub...

  18. Hierarchical Kinematic Modelling and Optimal Design of a Novel Hexapod Robot with Integrated Limb Mechanism

    Directory of Open Access Journals (Sweden)

    Guiyang Xin

    2015-09-01

    Full Text Available This paper presents a novel hexapod robot, hereafter named PH-Robot, with three degrees of freedom (3-DOF parallel leg mechanisms based on the concept of an integrated limb mechanism (ILM for the integration of legged locomotion and arm manipulation. The kinematic model plays an important role in the parametric optimal design and motion planning of robots. However, models of parallel mechanisms are often difficult to obtain because of the implicit relationship between the motions of actuated joints and the motion of a moving platform. In order to derive the kinematic equations of the proposed hexapod robot, an extended hierarchical kinematic modelling method is proposed. According to the kinematic model, the geometrical parameters of the leg are optimized utilizing a comprehensive objective function that considers both dexterity and payload. PH-Robot has distinct advantages in accuracy and load ability over a robot with serial leg mechanisms through the former's comparison of performance indices. The reachable workspace of the leg verifies its ability to walk and manipulate. The results of the trajectory tracking experiment demonstrate the correctness of the kinematic model of the hexapod robot.

  19. Mechanical characterization of soft viscoelastic gels via indentation and optimization-based inverse finite element analysis.

    Science.gov (United States)

    Liu, Kaifeng; VanLandingham, Mark R; Ovaert, Timothy C

    2009-08-01

    Polymer gels are widely accepted as candidate materials for tissue engineering, drug delivery, and orthopedic load-bearing applications. In addition, their mechanical and physical properties can be tailored to meet a wide range of design requirements. For soft gels whose elastic modulus is in the kPa range, mechanical characterization by bulk mechanical testing methods presents challenges, for example, in sample preparation, fixture design, gripping, and/or load measurement accuracy. Nanoindentation, however, has advantages when characterizing the mechanical properties of soft materials. This study was aimed at investigating the application of an inverse finite element analysis technique to identify material parameters of polymer gels via nanoindentation creep testing, optimization, and finite element simulation. Nanoindentation experiments were conducted using a rigid circular flat punch, and then simulated using the commercial software ABAQUS. The optimization (error minimization) procedure was integrated in the parameter determination process using a Matlab shell program, which makes this approach readily adaptable to other test geometries and material models. The finite element results compare well with a derived analytical viscoelastic solution for a rigid circular flat punch on a Kelvin-Voigt half-space.

  20. Potentiating the cellular targeting and anti-tumor activity of Dp44mT via binding to human serum albumin: two saturable mechanisms of Dp44mT uptake by cells.

    Science.gov (United States)

    Merlot, Angelica M; Sahni, Sumit; Lane, Darius J R; Fordham, Ashleigh M; Pantarat, Namfon; Hibbs, David E; Richardson, Vera; Doddareddy, Munikumar R; Ong, Jennifer A; Huang, Michael L H; Richardson, Des R; Kalinowski, Danuta S

    2015-04-30

    Di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT) demonstrates potent anti-cancer activity. We previously demonstrated that 14C-Dp44mT enters and targets cells through a carrier/receptor-mediated uptake process. Despite structural similarity, 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT) and pyridoxal isonicotinoyl hydrazone (PIH) enter cells via passive diffusion. Considering albumin alters the uptake of many drugs, we examined the effect of human serum albumin (HSA) on the cellular uptake of Dp44mT, Bp4eT and PIH. Chelator-HSA binding studies demonstrated the following order of relative affinity: Bp4eT≈PIH>Dp44mT. Interestingly, HSA decreased Bp4eT and PIH uptake, potentially due to its high affinity for the ligands. In contrast, HSA markedly stimulated Dp44mT uptake by cells, with two saturable uptake mechanisms identified. The first mechanism saturated at 5-10 µM (B(max):1.20±0.04 × 10⁷ molecules/cell; K(d):33±3 µM) and was consistent with a previously identified Dp44mT receptor/carrier. The second mechanism was of lower affinity, but higher capacity (B(max):2.90±0.12 × 10⁷ molecules/cell; K(d):65±6 µM), becoming saturated at 100 µM and was only evident in the presence of HSA. This second saturable Dp44mT uptake process was inhibited by excess HSA and had characteristics suggesting it was mediated by a specific binding site. Significantly, the HSA-mediated increase in the targeting of Dp44mT to cancer cells potentiated apoptosis and could be important for enhancing efficacy.

  1. Multifunctional organic–inorganic hybrid nanoparticles and nanosheets based on chitosan derivative and layered double hydroxide: cellular uptake mechanism and application for topical ocular drug delivery

    Directory of Open Access Journals (Sweden)

    Chi H

    2017-02-01

    Full Text Available Huibo Chi,1,2,* Yan Gu,1,* Tingting Xu,1 Feng Cao1 1Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, 2State Key Laboratory of Drug Delivery Technology and Pharmacokinetics, Tianjin Institute of Pharmaceutical Research Co., Ltd., Tianjin, People’s Republic of China *These authors contributed equally to this work Abstract: To study the cellular uptake mechanism of multifunctional organic–inorganic hybrid nanoparticles and nanosheets, new chitosan–glutathione–valine–valine-layered double hydroxide (CG-VV-LDH nanosheets with active targeting to peptide transporter-1 (PepT-1 were prepared, characterized and further compared with CG-VV-LDH nanoparticles. Both organic–inorganic hybrid nanoparticles and nanosheets showed a sustained release in vitro and prolonged precorneal retention time in vivo, but CG-VV-LDH nanoparticles showed superior permeability in the isolated cornea of rabbits than CG-VV-LDH nanosheets. Furthermore, results of cellular uptake on human corneal epithelial primary cells (HCEpiC and retinal pigment epithelial (ARPE-19 cells indicated that both clathrin-mediated endocytosis and active transport of PepT-1 are involved in the internalization of CG-VV-LDH nanoparticles and CG-VV-LDH nanosheets. In summary, the CG-VV-LDH nanoparticle may be a promising carrier as a topical ocular drug delivery system for the treatment of ocular diseases of mid-posterior segments, while the CG-VV-LDH nanosheet may be suitable for the treatment of ocular surface diseases. Keywords: LDH nanoparticles, LDH nanosheets, ocular drug delivery, human corneal epithelial primary cell, retinal pigment cell, ARPE-19, active targeting

  2. Ecophysiological mechanisms characterising fen and bog species: focus on variations in nitrogen uptake traits under different soil-water pH.

    Science.gov (United States)

    Nakamura, Takatoshi; Nakamura, Motoka

    2012-04-01

    Although the productivity and nitrogen (N)-use traits of mire plants differ dramatically between fens and bogs, soil N richness does not necessarily differ, whereas the soil-water pH is distinctly lower in bogs than in fens. The ecophysiological mechanisms underlying these relations are unclear. To assess the relative availability of N forms in relation to soil-water pH, we focused on the net N uptake rate per unit root weight (NNUR), glutamine synthetase activity and nitrate reductase activity, and performed reciprocal transplant experiments with the seedlings of fen (Carex lyngbyei) and bog (C. middendorffii) sedge species in intact habitat sites. The soil-water pH was clearly lower at the bog site, but the NH(4) (+), NO(3) (-) or dissolved organic-N concentrations did not differ between the fen and bog sites. The activity of both enzymes for inorganic-N assimilation did not differ among the sites and species. However, the fen species grown at bog sites showed a drastic decrease in the NNUR, suggesting a suppression of organic-N uptake. The bog species showed no NNUR difference between the sites. These results indicate that inorganic-N availability does not differ between the two habitats, but organic-N availability is lowered in a low-pH bog, particularly in the case of fen species. Therefore, the relative availability of N forms shows species-specific variations that depend on the differences in the soil-water pH of root zone, even at similar N richness, which would play a key role in plant distribution strategies in relation to the fen-bog gradient.

  3. Myeloid cells expressing VEGF and arginase-1 following uptake of damaged retinal pigment epithelium suggests potential mechanism that drives the onset of choroidal angiogenesis in mice.

    Directory of Open Access Journals (Sweden)

    Jian Liu

    Full Text Available Whilst data recognise both myeloid cell accumulation during choroidal neovascularisation (CNV as well as complement activation, none of the data has presented a clear explanation for the angiogenic drive that promotes pathological angiogenesis. One possibility that is a pre-eminent drive is a specific and early conditioning and activation of the myeloid cell infiltrate. Using a laser-induced CNV murine model, we have identified that disruption of retinal pigment epithelium (RPE and Bruch's membrane resulted in an early recruitment of macrophages derived from monocytes and microglia, prior to angiogenesis and contemporaneous with lesional complement activation. Early recruited CD11b(+ cells expressed a definitive gene signature of selective inflammatory mediators particularly a pronounced Arg-1 expression. Accumulating macrophages from retina and peripheral blood were activated at the site of injury, displaying enhanced VEGF expression, and notably prior to exaggerated VEGF expression from RPE, or earliest stages of angiogenesis. All of these initial events, including distinct VEGF (+ Arg-1(+ myeloid cells, subsided when CNV was established and at the time RPE-VEGF expression was maximal. Depletion of inflammatory CCR2-positive monocytes confirmed origin of infiltrating monocyte Arg-1 expression, as following depletion Arg-1 signal was lost and CNV suppressed. Furthermore, our in vitro data supported a myeloid cell uptake of damaged RPE or its derivatives as a mechanism generating VEGF (+ Arg-1(+ phenotype in vivo. Our results reveal a potential early driver initiating angiogenesis via myeloid-derived VEGF drive following uptake of damaged RPE and deliver an explanation of why CNV develops during any of the stages of macular degeneration and can be explored further for therapeutic gain.

  4. Optimism

    Science.gov (United States)

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  5. Optimization of metabolite detection by quantum mechanics simulations in magnetic resonance spectroscopy.

    Science.gov (United States)

    Gambarota, Giulio

    2016-09-03

    Magnetic resonance spectroscopy (MRS) is a well established modality for investigating tissue metabolism in vivo. In recent years, many efforts by the scientific community have been directed towards the improvement of metabolite detection and quantitation. Quantum mechanics simulations allow for investigations of the MR signal behaviour of metabolites; thus, they provide an essential tool in the optimization of metabolite detection. In this review, we will examine quantum mechanics simulations based on the density matrix formalism. The density matrix was introduced by von Neumann in 1927 to take into account statistical effects within the theory of quantum mechanics. We will discuss the main steps of the density matrix simulation of an arbitrary spin system and show some examples for the strongly coupled two spin system.

  6. Thyroid Scan and Uptake

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses ... the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a ...

  7. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses ... the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a ...

  8. Thyroid Scan and Uptake

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses small ... Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a type ...

  9. Optimally oriented grooves on dental implants improve bone quality around implants under repetitive mechanical loading.

    Science.gov (United States)

    Kuroshima, Shinichiro; Nakano, Takayoshi; Ishimoto, Takuya; Sasaki, Muneteru; Inoue, Maaya; Yasutake, Munenori; Sawase, Takashi

    2017-01-15

    The aim was to investigate the effect of groove designs on bone quality under controlled-repetitive load conditions for optimizing dental implant design. Anodized Ti-6Al-4V alloy implants with -60° and +60° grooves around the neck were placed in the proximal tibial metaphysis of rabbits. The application of a repetitive mechanical load was initiated via the implants (50N, 3Hz, 1800 cycles, 2days/week) at 12weeks after surgery for 8weeks. Bone quality, defined as osteocyte density and degree of biological apatite (BAp) c-axis/collagen fibers, was then evaluated. Groove designs did not affect bone quality without mechanical loading; however, repetitive mechanical loading significantly increased bone-to-implant contact, bone mass, and bone mineral density (BMD). In +60° grooves, the BAp c-axis/collagen fibers preferentially aligned along the groove direction with mechanical loading. Moreover, osteocyte density was significantly higher both inside and in the adjacent region of the +60° grooves, but not -60° grooves. These results suggest that the +60° grooves successfully transmitted the load to the bone tissues surrounding implants through the grooves. An optimally oriented groove structure on the implant surface was shown to be a promising way for achieving bone tissue with appropriate bone quality. This is the first report to propose the optimal design of grooves on the necks of dental implants for improving bone quality parameters as well as BMD. The findings suggest that not only BMD, but also bone quality, could be a useful clinical parameter in implant dentistry.

  10. Failure Mechanisms and Structural Optimization of Shredder Hammer for Metal Scraps

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xianyan; HU Zhili; TAO Yijun; QIN Xunpeng; HUA Lin

    2016-01-01

    Recycling retired cars can relieve the environmental pollution and resource waste efficiently. However, a few publications can be found on the failure mechanisms and optimization method of recycling equipment, shredders. Thus, the failure mechanisms and structural optimization of shredder hammers for retired cars are studied aiming improving shredding efficiency and reducing cost. Failure types of shredder hammer are studied theoretically, and it is found that wear failure and fatigue failure are the two main failure types of shredder hammer. The shredding process of metal scraps is analyzed by finite element method, and it can be divided into four stages based on the stress states: initial stage, collision stage, grinding stage and separation stage. It is proved that the shredding efficiency can be improved by increasing cutouts on the hammer head. Finally, it is determined that the hammer with two cutouts is the optimal structure for metal scraps, which can improve the shredding efficiency by 20% and lengthen the hammer life by 15%. This study provides scientific basis for the industry application and theoretical foundation for further research.

  11. Failure mechanisms and structural optimization of shredder hammer for metal scraps

    Science.gov (United States)

    Zhou, Xianyan; Hu, Zhili; Tao, Yijun; Qin, Xunpeng; Hua, Lin

    2016-07-01

    Recycling retired cars can relieve the environmental pollution and resource waste efficiently. However, a few publications can be found on the failure mechanisms and optimization method of recycling equipment, shredders. Thus, the failure mechanisms and structural optimization of shredder hammers for retired cars are studied aiming improving shredding efficiency and reducing cost. Failure types of shredder hammer are studied theoretically, and it is found that wear failure and fatigue failure are the two main failure types of shredder hammer. The shredding process of metal scraps is analyzed by finite element method, and it can be divided into four stages based on the stress states: initial stage, collision stage, grinding stage and separation stage. It is proved that the shredding efficiency can be improved by increasing cutouts on the hammer head. Finally, it is determined that the hammer with two cutouts is the optimal structure for metal scraps, which can improve the shredding efficiency by 20% and lengthen the hammer life by 15%. This study provides scientific basis for the industry application and theoretical foundation for further research.

  12. Artificial bee colony algorithm with comprehensive search mechanism for numerical optimization

    Institute of Scientific and Technical Information of China (English)

    Mudong Li; Hui Zhao; Xingwei Weng; Hanqiao Huang

    2015-01-01

    The artificial bee colony (ABC) algorithm is a sim-ple and effective global optimization algorithm which has been successful y applied in practical optimization problems of various fields. However, the algorithm is stil insufficient in balancing ex-ploration and exploitation. To solve this problem, we put forward an improved algorithm with a comprehensive search mechanism. The search mechanism contains three main strategies. Firstly, the heuristic Gaussian search strategy composed of three different search equations is proposed for the employed bees, which ful y utilizes and balances the exploration and exploitation of the three different search equations by introducing the selectivity probability Ps. Secondly, in order to improve the search accuracy, we propose the Gbest-guided neighborhood search strategy for onlooker bees to improve the exploitation performance of ABC. Thirdly, the self-adaptive population perturbation strategy for the current colony is used by random perturbation or Gaussian perturbation to en-hance the diversity of the population. In addition, to improve the quality of the initial population, we introduce the chaotic opposition-based learning method for initialization. The experimental results and Wilcoxon signed ranks test based on 27 benchmark func-tions show that the proposed algorithm, especial y for solving high dimensional and complex function optimization problems, has a higher convergence speed and search precision than ABC and three other current ABC-based algorithms.

  13. Ionic mechanism underlying optimal stimuli for neuronal excitation: role of Na+ channel inactivation.

    Science.gov (United States)

    Clay, John R; Forger, Daniel B; Paydarfar, David

    2012-01-01

    The ionic mechanism underlying optimal stimulus shapes that induce a neuron to fire an action potential, or spike, is relevant to understanding optimal information transmission and therapeutic stimulation in the nervous system. Here we analyze for the first time the ionic basis for stimulus optimality in the Hodgkin and Huxley model and for eliciting a spike in squid giant axons, the preparation for which the model was devised. The experimentally determined stimulus is a smoothly varying biphasic current waveform having a relatively long and shallow hyperpolarizing phase followed by a depolarizing phase of briefer duration. The hyperpolarizing phase removes a small degree of the resting level of Na(+) channel inactivation. This result together with the subsequent depolarizing phase provides a signal that is energetically more efficient for eliciting spikes than rectangular current pulses. Sodium channel inactivation is the only variable that is changed during the stimulus waveform, other than the membrane potential, V. The activation variables for Na(+) and K(+) channels are unchanged throughout the stimulus. This result demonstrates how an optimal stimulus waveform relates to ionic dynamics and may have implications for energy efficiency of neural excitation in many systems including the mammalian brain.

  14. OPTIMIZING DESIGN OF MECHANICAL SELF-CENTERING DEVICE FOR SUSPENSION HEIGHT*

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Firstly, in view of the respective defects of existing self-centering devices for vehicle suspension height, the design scheme of the proposed mechanical self-centering device for suspension height is described. Taking the rear suspension of a certain light bus as a research example, the structures and parameters of the novel device are designed and ascertained. Then, the road excitation models, the performance evaluation indexes and the half-vehicle model are built, the simulation outputs of time and frequency domain are obtained with the road excitations of random and pulse by using MATLAB/Simulink software. So the main characteristics of the self-centering suspension are presented preliminarily. Finally, a multi-objective parameter design optimization model for the self-centering device is built by weighted sum approach, and optimal solution is obtained by adopting complex approach. The relevant choosing-type parameters for self-centering device components are deduced by using discrete variable optimal method, and the optimal results are verified and analyzed. So the performance potentials of the self-centering device are exerted fully in condition of ensuring overall suspension performances.

  15. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  16. Experimental Observation of the Skeletal Adaptive Repair Mechanism and Bionic Topology Optimization Method

    Directory of Open Access Journals (Sweden)

    Kaysar Rahman

    2014-01-01

    Full Text Available Bone adaptive repair theory considers that the external load is the direct source of bone remodeling; bone achieves its maintenance by remodeling some microscopic damages due to external load during the process. This paper firstly observes CT data from the whole self-repairing process in bone defects in rabbit femur. Experimental result shows that during self-repairing process there exists an interaction relationship between spongy bone and enamel bone volume changes of bone defect, that is when volume of spongy bone increases, enamel bone decreases, and when volume of spongy bone decreases, enamel bone increases. Secondly according to this feature a bone remodeling model based on cross-type reaction-diffusion system influenced by mechanical stress is proposed. Finally, this model coupled with finite element method by using the element adding and removing process is used to simulate the self-repairing process and engineering optimization problems by considering the idea of bionic topology optimization.

  17. Enhancement and Optimization Mechanisms of Biogas Production for Rural Household Energy in Developing Countries: A review

    Directory of Open Access Journals (Sweden)

    Yitayal Addis Alemayehu

    2015-10-01

    Full Text Available Anaerobic digestion is common but vital process used for biogas and fertilizer production as well as one method for waste treatment. The process is currently used in developing countries primarily for biogas production in the household level of rural people. The aim of this review is to indicate possible ways of including rural households who own less than four heads of cattle for the biogas programs in developing countries. The review provides different research out puts on using biogas substrates other than cow dung or its mix through different enhancement and optimization mechanisms. Many biodegradable materials have been studied for alternative methane production. Therefore, these substrates could be used for production by addressing the optimum conditions for each factor and each processes for enhanced and optimized biogas production.

  18. Thermo-mechanical fatigue reliability optimization of PBGA solder joints based on ANN-PSO

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ji-cheng; XIAO Xiao-qing; EN Yun-fei; CHEN Ni; WANG Xiang-zhong

    2008-01-01

    Based on a method combined artificial neural network (ANN) with particle swarm optimization (PSO) algorithm, the thermo-mechanical fatigue reliability of plastic ball grid array (PBGA) solder joints was studied. The simulation experiments of accelerated thermal cycling test were performed by ANSYS software. Based on orthogonal array experiments, a back-propagation artificial neural network (BPNN) was used to establish the nonlinear multivariate relationship between thermo-mechanical fatigue reliability and control factors. Then, PSO was applied to obtaining the optimal levels of control factors by using the output of BPNN as the affinity measure. The results show that the control factors, such as print circuit board (PCB) size, PCB thickness, substrate size,substrate thickness, PCB coefficient of thermal expansion (CTE), substrate CTE, silicon die CTE, and solder joint CTE, have a great influence on thermo-mechanical fatigue reliability of PBGA solder joints. The ratio of signal to noise of ANN-PSO method is 51.77dB and its error is 33.3% less than that of Taguchi method. Moreover, the running time of ANN-PSO method is only 2% of that of the BPNN. These conclusions are verified by the confirmative experiments.

  19. COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACOUES SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    Radisav D. Vidic

    2002-05-01

    The first part of this study evaluated the application of a versatile optical technique to study the adsorption and desorption of model adsorbates representative of volatile polar (acetone) and non-polar (propane) organic compounds on a model carbonaceous surface under ultra high vacuum (UHV) conditions. The results showed the strong correlation between optical differential reflectance (ODR) and adsorbate coverage determined by temperature programmed desorption (TPD). ODR technique was proved to be a powerful tool to investigate surface adsorption and desorption from UHV to high pressure conditions. The effects of chemical functionality and surface morphology on the adsorption/desorption behavior of acetone, propane and mercury were investigated for two model carbonaceous surfaces, namely air-cleaved highly oriented pyrolytic graphite (HOPG) and plasma-oxidized HOPG. They can be removed by thermal treatment (> 500 K). The presence of these groups almost completely suppresses propane adsorption at 90K and removal of these groups leads to dramatic increase in adsorption capacity. The amount of acetone adsorbed is independent of surface heat treatment and depends only on total exposure. The effects of morphological heterogeneity is evident for plasma-oxidized HOPG as this substrate provides greater surface area, as well as higher energy binding sites. Mercury adsorption at 100 K on HOPG surfaces with and without chemical functionalities and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from HOPG surface enhances mercury physisorption. Plasma oxidation of HOPG provides additional surface area for mercury adsorption. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms, physisorption below 348 K and chemisorption above 348 K. No significant impact of oxygen functionalities was observed in the chemisorption region. The key findings of this study

  20. The right time to learn: mechanisms and optimization of spaced learning.

    Science.gov (United States)

    Smolen, Paul; Zhang, Yili; Byrne, John H

    2016-02-01

    For many types of learning, spaced training, which involves repeated long inter-trial intervals, leads to more robust memory formation than does massed training, which involves short or no intervals. Several cognitive theories have been proposed to explain this superiority, but only recently have data begun to delineate the underlying cellular and molecular mechanisms of spaced training, and we review these theories and data here. Computational models of the implicated signalling cascades have predicted that spaced training with irregular inter-trial intervals can enhance learning. This strategy of using models to predict optimal spaced training protocols, combined with pharmacotherapy, suggests novel ways to rescue impaired synaptic plasticity and learning.

  1. Optimal Bandwidth Scheduling of Networked Learning Control System Based on Nash Theory and Auction Mechanism

    Directory of Open Access Journals (Sweden)

    Xiang Yan

    2013-01-01

    Full Text Available This paper addresses the optimal bandwidth scheduling problem for a double-layer networked learning control system (NLCS. To deal with this issue, auction mechanism is employed, and a dynamic bandwidth scheduling methodology is proposed to allocate the bandwidth for each subsystem. A noncooperative game fairness model is formulated, and the utility function of subsystems is designed. Under this framework, estimation of distribution algorithm (EDA is used to obtain Nash equilibrium for NLCS. Finally, simulation and experimental results are given to demonstrate the effectiveness of the proposed approach.

  2. Strength analysis and optimization of welding robot mechanism in emergency stop state

    Directory of Open Access Journals (Sweden)

    Zdeněk Poruba

    2016-03-01

    Full Text Available The contribution deals with the strength analysis and optimization of the welding robot mechanism in emergency stop state. The common operational positioning of the welding robot is characterized by smooth course of speeds in the time. The resulting load does not differ significantly from the static loading. However the safety requirements given by the norm require the ability of emergency stop function. Since the course of speed in time is rather steep the higher values of acceleration and thus higher excitation force is expected. The dynamical simulation performed describes the response of the robot mechanism in the form of stress course in time, quantifies the peak values of the stress caused by the dynamical component of loading and highlights the potential risks associated with this phenomenon.

  3. Optimization of a spherical mechanism for a minimally invasive surgical robot: theoretical and experimental approaches.

    Science.gov (United States)

    Lum, Mitchell J H; Rosen, Jacob; Sinanan, Mika N; Hannaford, Blake

    2006-07-01

    With a focus on design methodology for developing a compact and lightweight minimally invasive surgery (MIS) robot manipulator, the goal of this study is progress toward a next-generation surgical robot system that will help surgeons deliver healthcare more effectively. Based on an extensive database of in-vivo surgical measurements, the workspace requirements were clearly defined. The pivot point constraint in MIS makes the spherical manipulator a natural candidate. An experimental evaluation process helped to more clearly understand the application and limitations of the spherical mechanism as an MIS robot manipulator. The best configuration consists of two serial manipulators in order to avoid collision problems. A complete kinematic analysis and optimization incorporating the requirements for MIS was performed to find the optimal link lengths of the manipulator. The results show that for the serial spherical 2-link manipulator used to guide the surgical tool, the optimal link lengths (angles) are (60 degrees, 50 degrees). A prototype 6-DOF surgical robot has been developed and will be the subject of further study.

  4. Problems of optimal transportation on the circle and their mechanical applications

    Science.gov (United States)

    Plakhov, Alexander; Tchemisova, Tatiana

    2017-02-01

    We consider a mechanical problem concerning a 2D axisymmetric body moving forward on the plane and making slow turns of fixed magnitude about its axis of symmetry. The body moves through a medium of non-interacting particles at rest, and collisions of particles with the body's boundary are perfectly elastic (billiard-like). The body has a blunt nose: a line segment orthogonal to the symmetry axis. It is required to make small cavities with special shape on the nose so as to minimize its aerodynamic resistance. This problem of optimizing the shape of the cavities amounts to a special case of the optimal mass transportation problem on the circle with the transportation cost being the squared Euclidean distance. We find the explicit solution for this problem when the amplitude of rotation is smaller than a fixed critical value, and give a numerical solution otherwise. As a by-product, we get explicit description of the solution for a class of optimal transportation problems on the circle.

  5. Economical Optimization of the Mechanized Longwall Faces with Top Coal Caving Mining, In Horizontal Slices

    Science.gov (United States)

    Onica, Ilie; Mihăilescu, Viorel; Andrioni, Felicia

    2016-09-01

    To increase the economic and technical performances of the Jiu Valley hard coal mines, the top coal caving, in horizontal slices, mining methods (Bourbaki methods) were introduced, adapted to the local geo-mining conditions. This mining was successfully experimented by using classical technology, using the individual supports and coal blasting. In the future, it is planned to adopt the mechanized technology, with frame supports and shearers. The mechanized longwall faces with top coal caving mining, in horizontal slices, of coal seam no. 3 could be efficient only if the sizes of the top coal height and the panel length determine a minimum cost of production. Therefore, the goal of this paper is the optimization of these parameters, from a technical and economic point of view, taking into account the general model of the cost function, at the panel level. For that, it was necessary to make a certain sequence of analysis involving: technological unit establishment, purpose function and optimizing model. Thus, there attaining to the mathematical model of the unit cost, after determination of all the individual calculation articles, regarding the preparatory workings, coal face equipments, materials, energy, workforce, etc. Because of the complexity of the obtained technical and economic model, to determine the optimum sizes of the panel length and top coal height, it was necessary to archive a sensitivity analysis of the unit cost function to the main parameters implied into this mathematical model.

  6. Optimization of the dye-sensitized solar cell performance by mechanical compression.

    Science.gov (United States)

    Meen, Teen Hang; Tsai, Jenn Kai; Tu, Yu Shin; Wu, Tian Chiuan; Hsu, Wen Dung; Chang, Shoou-Jinn

    2014-01-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV-vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm(2), the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm(2), and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized.

  7. Statistical mechanical analysis of linear programming relaxation for combinatorial optimization problems

    Science.gov (United States)

    Takabe, Satoshi; Hukushima, Koji

    2016-05-01

    Typical behavior of the linear programming (LP) problem is studied as a relaxation of the minimum vertex cover (min-VC), a type of integer programming (IP) problem. A lattice-gas model on the Erdös-Rényi random graphs of α -uniform hyperedges is proposed to express both the LP and IP problems of the min-VC in the common statistical mechanical model with a one-parameter family. Statistical mechanical analyses reveal for α =2 that the LP optimal solution is typically equal to that given by the IP below the critical average degree c =e in the thermodynamic limit. The critical threshold for good accuracy of the relaxation extends the mathematical result c =1 and coincides with the replica symmetry-breaking threshold of the IP. The LP relaxation for the minimum hitting sets with α ≥3 , minimum vertex covers on α -uniform random graphs, is also studied. Analytic and numerical results strongly suggest that the LP relaxation fails to estimate optimal values above the critical average degree c =e /(α -1 ) where the replica symmetry is broken.

  8. Optimizing the structure of financial resources of industrial enterprises in the market economy mechanism

    Directory of Open Access Journals (Sweden)

    A. Vlasov

    2015-01-01

    Full Text Available The article deals with the optimization of the structure of financial resources of industrial enterprises in the market economy mechanism. The slowdown of the Russian economy force companies to promote more accurate system financial planning its activities. In modern economic conditions the company's performance is largely dependent on the ability of management to more accurately predict financial flows, as well as more accurately predict the financial and human resources to ensure solvency of the enterprise, thus more competent to form the strategy of development of the organization.Goal / task. The aim of the article the search for the optimal structure of financial resources of industrial enterprises in the market economy mechanism and to develop proposals for the sustainable development of the enterprise. The task of this article is to investigate the structure of financial resources of the enterprise, in a deteriorating economic situation that must be considered in the sustainable development of industrial enterprises.Methodology. In conducting this study the main sources of the original data were the materials of the state statistics, the works of famous economists. The basis of the methodological developments based on comparative methods of analysis.Results. Given the concept of optimizing the structure of financial resources of the industrial enterprises. It shows the influence of external and internal factors affecting the stability of the industrial enterprises. Highlighted the impact of the economic situation on the role of these factors.Conclusions / significance. In the current economic conditions of the state and the new economic realities, it is necessary to focus to industrial enterprises to conduct an effective economic policy, thereby improving the financial stability of the enterprise.

  9. A Critical Review of Methane Trapping Mechanism to Optimize CBM Production

    Directory of Open Access Journals (Sweden)

    Saleem Qadir Tunio

    2012-12-01

    Full Text Available Optimizing Coal Bed Methane (CBM production depends on the trapping mechanism of methane in the micro pores of coal bed. Methane is trapped in coal beds by adsorption on the free surface. The free surface is mainly available as the micro pores and partly as different cleats. The average percentage of micro pores (1.2x10-7 cm diameter in a coal increases with rank and ranges from 19.3% in lignites to 75% in anthracites. The effective molecular diameter of adsorbed methane is 4.1x10-8 cm suggesting a maximum of three molecules can be accommodated in a unit micro pore. The commitment of optimized production of methane depends on the amount adsorbed on the coal surface. Methane in the micro pore can be accommodated either by solution in pore water or adsorption or as free gas under pressure. If it is dissolved in water, then for CBM production it is not useful because the dissolved gas will be expelled during dewatering phase of the well completion. It is only the free gas and the adsorbed gas that need to be evaluated for optimized production. Langmuir assumed a mono-layer of adsorption in selective locales on the adsorbent whereas many of the present day models assumed multi-layers of adsorbates (BET: Stephen Brunauer, Paul Emmett and Edward Teller. Problem arises with the concept of layering during adsorption process whereby it is difficult to think of adsorption of methane over a methane layer. With higher pressure methane can be accommodated as free gas but will not be adsorbed on any methane surface. It is therefore necessary to understand how methane molecule is trapped in the micro pores of the coal bed in order to optimize the CBM production.

  10. Towards a luxury uptake process via microalgae--defining the polyphosphate dynamics.

    Science.gov (United States)

    Powell, Nicola; Shilton, Andy; Chisti, Yusuf; Pratt, Steven

    2009-09-01

    Microalgae in waste stabilization ponds (WSP) have been shown to accumulate polyphosphate. This luxury uptake of phosphorus is influenced by the wastewater phosphate concentration, light intensity and temperature, but the dynamics of how these factors affect luxury uptake with respect to time are not understood. With improved understanding of the dynamics of this mechanism and how it could be manipulated, a phosphorus removal process utilizing luxury uptake by microalgae might be developed. In this work, luxury uptake was investigated by chemical extraction of the acid-soluble and acid-insoluble fractions of polyphosphate in the microalgae. The results showed that the initial accumulation and subsequent utilization of both acid-soluble polyphosphate (ASP) and acid-insoluble polyphosphate (AISP) is a function of the wastewater phosphate concentration. It was found that light intensity influenced both the accumulation and utilization of ASP. The temperature influenced the accumulation of AISP. AISP is believed to be a form of phosphorus storage and ASP is involved in metabolism however, the results of this work show that ASP can also act as a short term form of phosphorus storage. To optimize luxury uptake by microalgae a 'luxury uptake pond' is proposed where the conditions the microalgae are exposed to can be manipulated. This 'luxury uptake pond' would be designed to expose the microalgae to a high phosphate concentration and high light intensity for a short period of time in order to achieve optimal polyphosphate accumulation. Subsequent harvesting would then remove the phosphorus rich microalgae from the system.

  11. Optimizing the mechanical properties of M50NiL steel by plasma nitrocarburizing

    Science.gov (United States)

    Zhang, C. S.; Yan, M. F.; Sun, Z.; Wang, Y. X.; You, Y.; Bai, B.; Chen, L.; Long, Z.; Li, R. W.

    2014-10-01

    In this study, plasma nitrocarburizing at various temperatures in the range of 460-540 °C were carried out on M50NiL steel in order to improve wear properties. The nitrocarburizing temperature was optimized to obtain the best wear properties. The phase composition, microstucture and microhardness profiles of nitrocarburized layers of M50NiL steel were characterized by XRD, optical microscope and Vickers microhardness measurements, respectively. Pin-on-disc tribometer and SEM equipped with EDS were applied to measure friction and wear properties and analyze wear mechanisms involved. XRD results show that the amount of ɛ-Fe2-3(N,C) phase increased as the nitrocarburizing temperature rose form 460 °C to 500 °C and then decreased at 540 °C, while the amount of γ‧-Fe4(N,C) phase increased as the treatment temperature rose. The hardness of the nitrocarburized layers showed an obvious improvement accompanied with the increasing nitrocarburizing temperature, and obtained the maximum surface hardness of 1287 HV at 540 °C. The results of wear tests carried out at various sliding speeds indicated that the wear mechanism depends on sliding speed rather than the nitrocarburizing temperature. With the increase of the sliding speed, the wear mechanism transfers from oxidation mode to abrasive mode. The gradually deceased wear rate of the specimen nitrocarburized at 500 °C with the increase of the sliding speed indicated the excellent wear resistance under high sliding speed condition. Therefore, 500 °C can be selected as an optimized nitrocarburizing temperature for M50NiL steel.

  12. Optimization of factors to obtain cassava starch films with improved mechanical properties

    Science.gov (United States)

    Monteiro, Mayra; Oliveira, Victor; Santos, Francisco; Barros Neto, Eduardo; Silva, Karyn; Silva, Rayane; Henrique, João; Chibério, Abimaelle

    2017-08-01

    In this study, was investigated the optimization of the factors that significantly influenced the mechanical property improvement of cassava starch films through complete factorial design 23. The factors to be analyzed were cassava starch, glycerol and modified clay contents. A regression model was proposed by the factorial analysis, aiming to estimate the condition of the individual factors investigated in the optimum state of the mechanical properties of the biofilm, using the following statistical tool: desirability function and response surface. The response variable that delimits the improvement of the mechanical property of the biofilm is the tensile strength, such improvement is obtained by maximizing the response variable. The factorial analysis showed that the best combination of factor configurations to reach the best response was found to be: with 5g of cassava starch, 10% of glycerol and 5% of modified clay, both percentages in relation to the dry mass of starch used. In addition, the starch biofilm showing the lowest response contained 2g of cassava starch, 0% of modified clay and 30% of glycerol, and was consequently considered the worst biofilm.

  13. Design, Optimization, and Mechanical Property Analysis of a Submicrometric Aluminium Alloy Connecting Rod

    Directory of Open Access Journals (Sweden)

    J. P. Fuertes

    2015-01-01

    Full Text Available Ultrafine grained materials have a great deal of both scientific and technological interest because they allow outstanding properties to be obtained. An improvement in the mechanical strength and in the ductility and a better fatigue behaviour are properties to be expected with these materials. However, in spite of the great number of scientific publications that deals with the mechanical property improvement, the number of practical applications of these materials is scant. In this present research work, equal channel angular pressing (ECAP is used as a severe plastic deformation process (SPD to obtain billets which are subsequently isothermally forged to obtain a connecting rod with submicrometric grain size. The optimization of the design process is shown as well as the die design. The objective variables to be fulfilled are the correct filling of the die and the required force to obtain the part. Moreover, a comparison is also included between the mechanical properties thus obtained and those obtained with traditional methods. Moreover, optical and SEM micrographs are also included in this research work.

  14. Thermo-mechanical and optical optimization of the molten salt receiver for a given heliostat field

    Science.gov (United States)

    Augsburger, Germain; Das, Apurba K.; Boschek, Erik; Clark, Michael M.

    2016-05-01

    The tower type molten salt solar thermal power plant has proven to be advantageous over other utility scale solar power plant configurations due to its scalability and provision of storage, thereby improving the dispatchability. The configuration consists of a molten salt central receiver (MSCR) located atop an optimally located tower within a heliostat field with thousands of mirrors. The MSCR receives the concentrated energy from the heliostat field which heats a molten salt heat transfer fluid for thermal storage and utilization in producing steam as and when required for power generation. The MSCR heat transfer surface consists of banks of tangent tubes arranged in panels. The combined cost of the heliostat field and the receiver is 40%-50% of the total plant cost, which calls for optimization to maximize their utilization. Several previous studies have looked into the optimum solar power plant size based on various site conditions. However, the combined optimization of the receiver and the heliostat field has not been reported before. This study looks into the optimum configuration of the receiver for a given heliostat field. An in-house tool has been developed to select and rank a few receiver surface configurations (typically <50) from a list of hundreds of thousands of possible options. The operating limits which the heliostat field needs to obey are defined for the ranked surface configurations based on several different design considerations (e.g. mechanical integrity, corrosion limits). The thermal output of the receiver configurations for a given heliostat field is maximized. A combined rank indicating the optimum configurations in descending order of preference is presented based on the performance and various other practical considerations (e.g. total surface area, cost of material, ability of aiming strategies to distribute the flux). The methodology thus provided can be used as a guideline to arrive at an optimum receiver configuration for a given

  15. Test selection and optimization for PHM based on failure evolution mechanism model

    Institute of Scientific and Technical Information of China (English)

    Jing Qiu; Xiaodong Tan; Guanjun Liu; Kehong LÜ

    2013-01-01

    The test selection and optimization (TSO) can improve the abilities of fault diagnosis, prognosis and health-state evalua-tion for prognostics and health management (PHM) systems. Tra-ditional y, TSO mainly focuses on fault detection and isolation, but they cannot provide an effective guide for the design for testa-bility (DFT) to improve the PHM performance level. To solve the problem, a model of TSO for PHM systems is proposed. Firstly, through integrating the characteristics of fault severity and propa-gation time, and analyzing the test timing and sensitivity, a testabi-lity model based on failure evolution mechanism model (FEMM) for PHM systems is built up. This model describes the fault evolution-test dependency using the fault-symptom parameter matrix and symptom parameter-test matrix. Secondly, a novel method of in-herent testability analysis for PHM systems is developed based on the above information. Having completed the analysis, a TSO model, whose objective is to maximize fault trackability and mini-mize the test cost, is proposed through inherent testability analysis results, and an adaptive simulated annealing genetic algorithm (ASAGA) is introduced to solve the TSO problem. Final y, a case of a centrifugal pump system is used to verify the feasibility and effectiveness of the proposed models and methods. The results show that the proposed technology is important for PHM systems to select and optimize the test set in order to improve their perfor-mance level.

  16. Optimized Data Transfers Based on the OpenCL Event Management Mechanism

    Directory of Open Access Journals (Sweden)

    Hiroyuki Takizawa

    2015-01-01

    Full Text Available In standard OpenCL programming, hosts are supposed to control their compute devices. Since compute devices are dedicated to kernel computation, only hosts can execute several kinds of data transfers such as internode communication and file access. These data transfers require one host to simultaneously play two or more roles due to the need for collaboration between the host and devices. The codes for such data transfers are likely to be system-specific, resulting in low portability. This paper proposes an OpenCL extension that incorporates such data transfers into the OpenCL event management mechanism. Unlike the current OpenCL standard, the main thread running on the host is not blocked to serialize dependent operations. Hence, an application can easily use the opportunities to overlap parallel activities of hosts and compute devices. In addition, the implementation details of data transfers are hidden behind the extension, and application programmers can use the optimized data transfers without any tricky programming techniques. The evaluation results show that the proposed extension can use the optimized data transfer implementation and thereby increase the sustained data transfer performance by about 18% for a real application accessing a big data file.

  17. Design and optimization of mechanically down-doped terahertz fiber directional couplers

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.;

    2014-01-01

    We present a thorough practical design optimization of broadband low loss, terahertz (THz) photonic crystal fiber directional couplers in which the two cores are mechanically down-doped with a triangular array of air holes. A figure of merit taking both the 3-dB bandwidth and loss of the coupler...... into account, is used for optimization of the structure parameters, given by the diameter and pitch of the cladding (d and Λ) and of the core (dc and Λc) air-hole structure. The coupler with Λ = 498.7 μm, dc= 324.2 μm, Λc = 74.8 μm, and dc = 32.5 μm is found to have the best performance at a center frequency...... of 1THz, with a bandwidth of 0.25 THz and a total device loss of 9.2 dB. The robustness of the optimum coupler to structural changes is investigated. © 2014 Optical Society of America....

  18. Optimization Of Simulations And Activities For A New Introductory Quantum Mechanics Curriculum

    CERN Document Server

    Kohnle, Antje; Hooley, Christopher; Torrance, Bruce

    2013-01-01

    The Institute of Physics New Quantum Curriculum (quantumphysics.iop.org) consists of online texts and interactive simulations with accompanying activities for an introductory course in quantum mechanics starting from two-level systems. We describe observation sessions and analysis of homework and survey responses used to optimize the simulations and activities in terms of clarity, ease-of-use, promoting exploration, sense-making and linking of multiple representations. This work led to revisions of simulations and activities and general design principles which have been incorporated wherever applicable. These include intuitive controls and on-demand text in the simulations and making explicit links between mathematical and physical representations in simulations and activities.

  19. OPTIMAL TORQUE CONTROL STRATEGY FOR PARALLEL HYBRID ELECTRIC VEHICLE WITH AUTOMATIC MECHANICAL TRANSMISSION

    Institute of Scientific and Technical Information of China (English)

    GU Yanchun; YIN Chengliang; ZHANG Jianwu

    2007-01-01

    In parallel hybrid electrical vehicle (PHEV) equipped with automatic mechanical transmission (AMT), the driving smoothness and the clutch abrasion are the primary considerations for powertrain control during gearshift and clutch operation. To improve these performance indexes of PHEV, a coordinated control system is proposed through the analyzing of HEV powertrain dynamic characteristics. Using the method of minimum principle, the input torque of transmission is optimized to improve the driving sinoothness of vehicle. Using the methods of fuzzy logic and fuzzy-PID, the engaging speed of clutch and the throttle opening of engine are manipulated to ensure the smoothness of clutch engagement and reduce the abrasion of clutch friction plates. The motor provides the difference between the required input torque of transmission and the torque transmitted through clutch plates. Results of simulation and experiments show that the proposed control strategy performs better than the contrastive control system, the smoothness of driving and the abrasion of clutch can be improved simultaneously.

  20. Microseconds simulations reveal a new sodium-binding site and the mechanism of sodium-coupled substrate uptake by LeuT.

    Science.gov (United States)

    Zomot, Elia; Gur, Mert; Bahar, Ivet

    2015-01-02

    The bacterial sodium-coupled leucine/alanine transporter LeuT is broadly used as a model system for studying the transport mechanism of neurotransmitters because of its structural and functional homology to mammalian transporters such as serotonin, dopamine, or norepinephrine transporters, and because of the resolution of its structure in different states. Although the binding sites (S1 for substrate, and Na1 and Na2 for two co-transported sodium ions) have been resolved, we still lack a mechanistic understanding of coupled Na(+)- and substrate-binding events. We present here results from extensive (>20 μs) unbiased molecular dynamics simulations generated using the latest computing technology. Simulations show that sodium binds initially the Na1 site, but not Na2, and, consistently, sodium unbinding/escape to the extracellular (EC) region first takes place at Na2, succeeded by Na1. Na2 diffusion back to the EC medium requires prior dissociation of substrate from S1. Significantly, Na(+) binding (and unbinding) consistently involves a transient binding to a newly discovered site, Na1″, near S1, as an intermediate state. A robust sequence of substrate uptake events coupled to sodium bindings and translocations between those sites assisted by hydration emerges from the simulations: (i) bindings of a first Na(+) to Na1″, translocation to Na1, a second Na(+) to vacated Na1″ and then to Na2, and substrate to S1; (ii) rotation of Phe(253) aromatic group to seclude the substrate from the EC region; and (iii) concerted tilting of TM1b and TM6a toward TM3 and TM8 to close the EC vestibule.

  1. Mechanical Property Optimization of FDM PLA in Shear with Multiple Objectives

    Science.gov (United States)

    Torres, Jonathan; Cotelo, José; Karl, Justin; Gordon, Ali P.

    2015-05-01

    This study presents the influences of key processing parameters on the resulting material properties of fused-deposition-modeled (FDM) polylactic acid (PLA) components tested in torsion. A reduced experimental matrix was produced through the use of a Taguchi L9 orthogonal array with three parameters at three levels each. The processing parameters included the layer thickness, infill density, and postprocessing heat-treatment time at 100°C. Testing of components at varying times is conducted to facilitate heat-treatment time testing range and show the effects of prolonged heating. The layer thickness and infill are tested across the entire useful range available for the FDM machine used. Shear stress-strain response curves are acquired and average ultimate shear strength, 0.2% yield strength, proportional limit, shear modulus, and fracture strain are calculated for each run. An analysis of results via regression analysis is used to determine influences levels of parameters of the mechanical properties. The layer thickness and infill density are shown to be of high importance when optimizing for strength, with heat-treatment implementation slightly improving the resulting properties. Ductility is mainly affected by infill and heat treatment, with layer thickness having only a slight effect on the fracture strain achieved. Recommendations are made based on results of a method to optimize for either strength or ductility and how to compromise between recommended settings when a balance between the two is desired. The ability to produce parts with mechanical properties at or near those of bulk PLA is shown.

  2. Optimal root arrangement of cereal crops

    Science.gov (United States)

    Jung, Yeonsu; Park, Keunhwan; Kim, Ho-Young

    2015-11-01

    The plant root absorbs water from the soil and supplies it to the rest part of the plant. It consists of a number of root fibers, through whose surfaces water uptake occurs. There is an intriguing observation that for most of cereal crops such as maize and wheat, the volume density of root in the soil declines exponentially as a function of depth. To understand this empirical finding, we construct a theoretical model of root water uptake, where mass transfer into root surface is modeled just as heat flux around a fin. Agreement between the theoretically predicted optimal root distribution in vertical direction and biological data supports the hypothesis that the plant root has evolved to achieve the optimal water uptake in competition with neighbors. This study has practical implication in the agricultural industry as well as optimal design of water transport networks in both micro- and macroscales. Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 08826, Korea.

  3. A novel experimental design method to optimize hydrophilic matrix formulations with drug release profiles and mechanical properties.

    Science.gov (United States)

    Choi, Du Hyung; Lim, Jun Yeul; Shin, Sangmun; Choi, Won Jun; Jeong, Seong Hoon; Lee, Sangkil

    2014-10-01

    To investigate the effects of hydrophilic polymers on the matrix system, an experimental design method was developed to integrate response surface methodology and the time series modeling. Moreover, the relationships among polymers on the matrix system were studied with the evaluation of physical properties including water uptake, mass loss, diffusion, and gelling index. A mixture simplex lattice design was proposed while considering eight input control factors: Polyethylene glycol 6000 (x1 ), polyethylene oxide (PEO) N-10 (x2 ), PEO 301 (x3 ), PEO coagulant (x4 ), PEO 303 (x5 ), hydroxypropyl methylcellulose (HPMC) 100SR (x6 ), HPMC 4000SR (x7 ), and HPMC 10(5) SR (x8 ). With the modeling, optimal formulations were obtained depending on the four types of targets. The optimal formulations showed the four significant factors (x1 , x2 , x3 , and x8 ) and other four input factors (x4 , x5 , x6 , and x7 ) were not significant based on drug release profiles. Moreover, the optimization results were analyzed with estimated values, targets values, absolute biases, and relative biases based on observed times for the drug release rates with four different targets. The result showed that optimal solutions and target values had consistent patterns with small biases. On the basis of the physical properties of the optimal solutions, the type and ratio of the hydrophilic polymer and the relationships between polymers significantly influenced the physical properties of the system and drug release. This experimental design method is very useful in formulating a matrix system with optimal drug release. Moreover, it can distinctly confirm the relationships between excipients and the effects on the system with extensive and intensive evaluations.

  4. Biosorption of Lead(II) by Arthrobacter sp. 25: Process Optimization and Mechanism.

    Science.gov (United States)

    Jin, Yu; Wang, Xin; Zang, Tingting; Hu, Yang; Hu, Xiaojing; Ren, Guangming; Xu, Xiuhong; Qu, Juanjuan

    2016-08-28

    In the present work, Arthrobacter sp. 25, a lead-tolerant bacterium, was assayed to remove lead(II) from aqueous solution. The biosorption process was optimized by response surface methodology (RSM) based on the Box-Behnken design. The relationships between dependent and independent variables were quantitatively determined by second-order polynomial equation and 3D response surface plots. The biosorption mechanism was explored by characterization of the biosorbent before and after biosorption using atomic force microscopy (AFM), scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the maximum adsorption capacity of 9.6 mg/g was obtained at the initial lead ion concentration of 108.79 mg/l, pH value of 5.75, and biosorbent dosage of 9.9 g/l (fresh weight), which was close to the theoretically expected value of 9.88 mg/g. Arthrobacter sp. 25 is an ellipsoidalshaped bacterium covered with extracellular polymeric substances. The biosorption mechanism involved physical adsorption and microprecipitation as well as ion exchange, and functional groups such as phosphoryl, hydroxyl, amino, amide, carbonyl, and phosphate groups played vital roles in adsorption. The results indicate that Arthrobacter sp. 25 may be potentially used as a biosorbent for low-concentration lead(II) removal from wastewater.

  5. Optimization Design of Double-parameter Shift Schedule of Tracked Vehicle with Hydrodynamic-mechanical Transmission%Optimization Design of Double-parameter Shift Schedule of Tracked Vehicle with Hydrodynamic-mechanical Transmission

    Institute of Scientific and Technical Information of China (English)

    武景燕; 魏巍; 曲婧瑶; 闫清东

    2011-01-01

    A kind of automatic shift schedule optimization method is provided for a tracked vehicle with hydrodynamic-mechanical transmission in order to improve its dynamic performance. A dynamic model of integrated hydrodynamic-mechanical transmission is built in MATLAB/Simdriveline environment, and an optimum shift schedule is derived by using iSight software to call the dynamic model above, then the shift schedule is achieved after optimization. The simulation results show that the method is significant to improve the dynamic performance and gear-shifting smoothness theoretically and practically.

  6. 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.

  7. On the Optimally Controlled Hydrostatic Mechanical Drive in Case of Flywheel Acceleration

    Directory of Open Access Journals (Sweden)

    V. A. Korsunskii

    2016-01-01

    Full Text Available An improving dynamic quality of vehicles and enhanced fuel efficiency are gained thanks to the combined power system (CPS, comprising a main energy source - internal combustion engine (ICE with an attained level of the power source - and an auxiliary energy source, i.e. an energy storage device (a flywheel.To solve this problem was developed a mathematical model of CPS comprising internal combustion engine and flywheel energy storage (FES with stepless drive.The stepless drive of the flywheel is made to be hydrostatic mechanical to raise the system efficiency. To reduce the drive weight and simplify the control system in the hydraulic part of the flywheel drive is used only one hydraulic unit being controlled.The paper presents a kinematic diagram of the track-type vehicle equipped with the CPS that has a hydrostatic mechanical drive of the flywheel and a mechanical transmission.A mathematical model of the system comprising an ICE, hydrostatic mechanical drive, and FES with stepless drive has been developed. This mathematical model was used to study the influence of ICE and flywheel drive parameters on the dynamic characteristics of the system.The paper estimates the impact of flywheel energy consumption, pressure in the hydraulic system, and control parameter of hydrostatic mechanical drive on the charging time of FES.The obtained piecewise linear law to control the regulation parameter of the hydraulic unit allows us to minimize the charging time of the flywheel at the short-term stops and in the parking area of a tracked vehicle equipped with a CPS.The causes affecting the performance of ‘ICE – drive – flywheel’ system in the course of the flywheel acceleration are a restricted maximum power of the engine, as well as a limited generating capacity, and a maximum flywheel drive hydro-system pressure.The obtained results allow us to determine rational parameters of the flywheel and the laws of drive control to provide their further

  8. Using GM (1,1 Optimized by MFO with Rolling Mechanism to Forecast the Electricity Consumption of Inner Mongolia

    Directory of Open Access Journals (Sweden)

    Huiru Zhao

    2016-01-01

    Full Text Available Accurate and reliable forecasting on annual electricity consumption will be valuable for social projectors and power grid operators. With the acceleration of electricity market reformation and the development of smart grid and the energy Internet, the modern electric power system is becoming increasingly complex in terms of structure and function. Therefore, electricity consumption forecasting has become a more difficult and challenging task. In this paper, a new hybrid electricity consumption forecasting method, namely grey model (1,1 (GM (1,1, optimized by moth-flame optimization (MFO algorithm with rolling mechanism (Rolling-MFO-GM (1,1, was put forward. The parameters a and b of GM (1,1 were optimized by employing moth-flame optimization algorithm (MFO, which is the latest natured-inspired meta-heuristic algorithm proposed in 2015. Furthermore, the rolling mechanism was also introduced to improve the precision of prediction. The Inner Mongolia case discussion shows the superiority of proposed Rolling-MFO-GM (1,1 for annual electricity consumption prediction when compared with least square regression (LSR, GM (1,1, FOA (fruit fly optimization-GM (1,1, MFO-GM (1,1, Rolling-LSR, Rolling-GM (1,1 and Rolling-FOA-GM (1,1. The grey forecasting model optimized by MFO with rolling mechanism can improve the forecasting performance of annual electricity consumption significantly.

  9. Polar Bear Optimization Algorithm: Meta-Heuristic with Fast Population Movement and Dynamic Birth and Death Mechanism

    Directory of Open Access Journals (Sweden)

    Dawid Połap

    2017-09-01

    Full Text Available In the proposed article, we present a nature-inspired optimization algorithm, which we called Polar Bear Optimization Algorithm (PBO. The inspiration to develop the algorithm comes from the way polar bears hunt to survive in harsh arctic conditions. These carnivorous mammals are active all year round. Frosty climate, unfavorable to other animals, has made polar bears adapt to the specific mode of exploration and hunting in large areas, not only over ice but also water. The proposed novel mathematical model of the way polar bears move in the search for food and hunt can be a valuable method of optimization for various theoretical and practical problems. Optimization is very similar to nature, similarly to search for optimal solutions for mathematical models animals search for optimal conditions to develop in their natural environments. In this method. we have used a model of polar bear behaviors as a search engine for optimal solutions. Proposed simulated adaptation to harsh winter conditions is an advantage for local and global search, while birth and death mechanism controls the population. Proposed PBO was evaluated and compared to other meta-heuristic algorithms using sample test functions and some classical engineering problems. Experimental research results were compared to other algorithms and analyzed using various parameters. The analysis allowed us to identify the leading advantages which are rapid recognition of the area by the relevant population and efficient birth and death mechanism to improve global and local search within the solution space.

  10. Optimal conditions in (/sup 3/H)-thymidine uptake studies to prevent radiation damage to cells. A scintimetric and cytofluorographic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Arguelles, A.; Llorente, L.; Diaz-Jouanen, E.; Alarcon-Segovia, D. (Instituto Nacional de la Nutricion, Mexico City)

    1981-12-01

    Cells subjected to nucleoside incorporation studies using radiolabelled materials may suffer radiation damage that can alter the results. Scintimetric and cytofluorographic analyses were performed to confirm this and to determine the optimal experimental doses of, and exposure times to, (/sup 3/H)-TdR, in order to prevent or minimize such radiation damage to cells. The results showed that cultures of human mononuclear cells should be pulsed with 0.125 ..mu..Ci for 14 hr when stimulated with phytohaemagglutinin, 0.125 ..mu..Ci for 18 hr when stimulated with pokeweed mitogen, 0.5 ..mu..Ci for 8 hr when stimulated with concanavalin A and 0.5 ..mu..Ci for 8 hr when subjected to allogeneic stimulus, in order to achieve optimal incorporation with minimal disturbances of the cell cycle.

  11. Optimization Methods From Theory to Design Scientific and Technological Aspects in Mechanics

    CERN Document Server

    Cavazzuti, Marco

    2013-01-01

    This book is about optimization techniques and is subdivided into two parts. In the first part a wide overview on optimization theory is presented. Optimization is presented as being composed of five topics, namely: design of experiment, response surface modeling, deterministic optimization, stochastic optimization, and robust engineering design. Each chapter, after presenting the main techniques for each part, draws application oriented conclusions including didactic examples. In the second part some applications are presented to guide the reader through the process of setting up a few optimization exercises, analyzing critically the choices which are made step by step, and showing how the different topics that constitute the optimization theory can be used jointly in an optimization process. The applications which are presented are mainly in the field of thermodynamics and fluid dynamics due to the author's background.

  12. Bone marrow mesenchymal stem cell therapy in ischemic stroke:mechanisms of action and treatment optimization strategies

    Institute of Scientific and Technical Information of China (English)

    Guihong Li; Fengbo Yu; Ting Lei; Haijun Gao; Peiwen Li; Yuxue Sun; Haiyan Huang; Qingchun Mu

    2016-01-01

    Animal and clinical studies have conifrmed the therapeutic effect of bone marrow mesenchymal stem cells on cerebral ischemia, but their mechanisms of action remain poorly understood. Here, we summarize the transplantation approaches, directional migration, differentiation, replacement, neural circuit reconstruction, angiogenesis, neurotrophic factor secretion, apoptosis, immunomodulation, multiple mechanisms of action, and optimization strategies for bone marrow mesenchymal stem cells in the treatment of ischemic stroke. We also explore the safety of bone marrow mesenchymal stem cell transplantation and conclude that bone marrow mesenchymal stem cell transplantation is an important direction for future treatment of cerebral ischemia. Determining the optimal timing and dose for the transplantation are important directions for future research.

  13. Effect of Uptake-one inhibitors on the uptake of norepinephrine and metaiodobenzylguanidine

    Energy Technology Data Exchange (ETDEWEB)

    Tobes, M.C.; Jaques, S. Jr.; Wieland, D.M.; Sisson, J.C.

    1985-08-01

    The mechanisms underlying the uptake of the radiopharmaceutical metaiodobenzylguanidine (MIBG) and the catecholamine norepinephrine (NE) were studied using cultured bovine adrenomedullary cells as an in vitro model system. Sodium-dependent and sodium-independent uptake systems have been identified and characterized for both MIBG and NE. The sodium-dependent uptake of Ne and MIBG was inhibited by the selective Uptake-one inhibitors, desmethylimipramine (DMI) and cocaine, whereas the sodium-independent uptake for NE and MIBG was much less sensitive to inhibition by these agents. The sodium-dependent uptake system fulfills the criteria for the neuronal Uptake-one system, and the sodium-independent uptake system fulfills the criteria for a passive diffusion mechanism. Arterial concentrations proximal to the dog adrenal were very small suggesting that the sodium-dependent (Uptake-one) system is predominant in vivo. Consistent with the in vitro observations, the in vivo uptake of MIBG and NE into dog adrenal medullae was effectively blocked by pretreatment with DMI or cocaine. Therefore, iodine-131 MIBG scintigraphy of the adrenal appears to reflect uptake by way of the Uptake-one system.

  14. Non-hybridization saturable mechanisms play a role in the uptake of (68)Ga-Labeled LNA-DNA mixmer antisense oligonucleotides in rats.

    Science.gov (United States)

    Lendvai, Gabor; Monazzam, Azita; Velikyan, Irina; Eriksson, Barbro; Josephsson, Raymond; Långström, Bengt; Bergström, Mats; Estrada, Sergio

    2009-09-01

    Oligonucleotides (ODN) are key molecules for the aim of preventing translation of a gene product or monitoring gene expression in tissues. However, multiple methodological and biological hurdles need to be solved before in vivo application in humans will be possible. For positron emission tomography (PET) investigations, a 20-mer DNA-locked nucleic acid (LNA) mixmer ODN specific for rat chromogranin-A mRNA was labeled with (68)Ga and its uptake was examined in vivo in rats with and without blocking of scavenger receptors by polyribonucleotides. In addition, uptake studies of (68)Ga-LNA were performed with respect to time and concentration in human and rat cell lines. The human cell lines did not express the target mRNA. Both polyinosinic acid (poly-I) and polyadenylic acid (poly-A) reduced the uptake in rat tissues and in human cell lines. Poly-I was found to be more effective in the liver whereas poly-A was more effective in the kidney. In addition, the blockade by poly-I was statistically significant in the pancreas, adrenal gland, bone marrow, intestine, testis, urinary bladder, muscle, parotid gland, and heart, whereas poly-A also caused significant reduction in pancreas, adrenal gland, and bone marrow but not as much as in kidney. Cell culture study showed a 2-phase dose-dependent uptake characteristic with a saturable and a passive diffusion-like phase; however, these 2 phases were not so well expressed in the rat cell line. The results suggest that scavenger receptors or other saturable processes unrelated to hybridization may be involved in the tissue uptake of (68)Ga-LNA and in the clearance of antisense ODN through the liver, kidney, spleen, and bone marrow. The fact that these processes may be sequence-dependent suggests that proof of in vivo hybridization through imaging may not be obtained by only comparing sense and antisense sequences and proving dose-dependency.

  15. A Nonhomogeneous Cuckoo Search Algorithm Based on Quantum Mechanism for Real Parameter Optimization.

    Science.gov (United States)

    Cheung, Ngaam J; Ding, Xue-Ming; Shen, Hong-Bin

    2017-02-01

    Cuckoo search (CS) algorithm is a nature-inspired search algorithm, in which all the individuals have identical search behaviors. However, this simple homogeneous search behavior is not always optimal to find the potential solution to a special problem, and it may trap the individuals into local regions leading to premature convergence. To overcome the drawback, this paper presents a new variant of CS algorithm with nonhomogeneous search strategies based on quantum mechanism to enhance search ability of the classical CS algorithm. Featured contributions in this paper include: 1) quantum-based strategy is developed for nonhomogeneous update laws and 2) we, for the first time, present a set of theoretical analyses on CS algorithm as well as the proposed algorithm, respectively, and conclude a set of parameter boundaries guaranteeing the convergence of the CS algorithm and the proposed algorithm. On 24 benchmark functions, we compare our method with five existing CS-based methods and other ten state-of-the-art algorithms. The numerical results demonstrate that the proposed algorithm is significantly better than the original CS algorithm and the rest of compared methods according to two nonparametric tests.

  16. Design of an optimal active stabilizer mechanism for enhancing vehicle rolling resistance

    Institute of Scientific and Technical Information of China (English)

    Yaghoub Pourasad; Mehdi Mahmoodi-k; Majid Oveisi

    2016-01-01

    Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes. The main objective of this work is to develop active control mechanism based on fuzzy logic controller (FLC) and linear quadratic regulator (LQR) for improving vehicle path following, roll and handling performances simultaneously. 3-DOF vehicle model including yaw rate, lateral velocity (lateral dynamic) and roll angle (roll dynamic) were developed. The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal. The effectiveness of proposed controller and vehicle model were evaluated during fishhook and single lane-change maneuvers. Simulation results demonstrate that in both cases (FLC and LQR controllers) by reducing roll angle, lateral acceleration and side slip angles remain under 0.6g and 4° during maneuver, which ensures vehicle stability and handling properties. Finally, the sensitivity and robustness analysis of developed controller for varying longitudinal speeds were investigated.

  17. Laccase-catalyzed decolorization of malachite green: performance optimization and degradation mechanism.

    Directory of Open Access Journals (Sweden)

    Jie Yang

    Full Text Available Malachite green (MG was decolorized by laccase (LacA of white-rot fungus Cerrena sp. with strong decolorizing ability. Decolorization conditions were optimized with response surface methodology. A highly significant quadratic model was developed to investigate MG decolorization with LacA, and the maximum MG decolorization ratio of 91.6% was predicted under the conditions of 2.8 U mL(-1 LacA, 109.9 mg L(-1 MG and decolorization for 172.4 min. Kinetic studies revealed the Km and kcat values of LacA toward MG were 781.9 mM and 9.5 s(-1, respectively. UV-visible spectra confirmed degradation of MG, and the degradation mechanism was explored with liquid chromatography-mass spectrometry (LC-MS analysis. Based on the LC-MS spectra of degradation products, LacA catalyzed MG degradation via two simultaneous pathways. In addition, the phytotoxicity of MG, in terms of inhibition on seed germination and seedling root elongation of Nicotiana tabacum and Lactuca sativa, was reduced after laccase treatment. These results suggest that laccase of Cerrena was effective in decolorizing MG and promising in bioremediation of wastewater in food and aquaculture industries.

  18. Optimization of the mechanism from equipment for overcoming obstacles with design of experiments

    Directory of Open Access Journals (Sweden)

    Gheorghiță Vlad

    2017-01-01

    Full Text Available A data collection considers how the experimental factors, controlled and uncontrolled, fit together into a model that will meet the specific objectives of an experiment and satisfy the practical constraints of resource and time. Customizing any product to improve performance requires a reliable method to measure performance results, in order to accurately assess the effects that design changes have on them. This paper has the purpose to analyse the equipment for overcoming obstacles. A comprehensive approach to model equipment requires performance data related to the design parameters. Slipping, slanting, becoming unstable, sliding, overturning and blocking while climbing steps and stairs are common problems and may cause instability for the user of the equipment. The Taguchi Method is used to optimize several parameters of the proposed mechanism and to ensure the stability through horizontality of the equipment. This method provides an opportunity to reduce the number of required sample size and is implemented by an orthogonal experimental array which enables the effect of multiple parameters to be simultaneously assessed.

  19. Compatibility Condition in Theory of Solid Mechanics (Elasticity, Structures, and Design Optimization)

    Science.gov (United States)

    Patnaik, Surya N.; Pai, Shantaram S.; Hopkins, Dale A.

    2007-01-01

    The strain formulation in elasticity and the compatibility condition in structural mechanics have neither been understood nor have they been utilized. This shortcoming prevented the formulation of a direct method to calculate stress. We have researched and understood the compatibility condition for linear problems in elasticity and in finite element analysis. This has lead to the completion of the method of force with stress (or stress resultant) as the primary unknown. The method in elasticity is referred to as the completed Beltrami-Michell formulation (CBMF), and it is the integrated force method (IFM) in structures. The dual integrated force method (IFMD) with displacement as the primary unknown has been formulated. IFM and IFMD produce identical responses. The variational derivation of the CBMF yielded the new boundary compatibility conditions. The CBMF can be used to solve stress, displacement, and mixed boundary value problems. The IFM in structures produced high-fidelity response even with a modest finite element model. The IFM has influenced structural design considerably. A fully utilized design method for strength and stiffness limitation has been developed. The singularity condition in optimization has been identified. The CBMF and IFM tensorial approaches are robust formulations because of simultaneous emphasis on the equilibrium equation and the compatibility condition.

  20. Optimization of light harvesting and photoprotection: molecular mechanisms and physiological consequences.

    Science.gov (United States)

    Horton, Peter

    2012-12-19

    The distinctive lateral organization of the protein complexes in the thylakoid membrane investigated by Jan Anderson and co-workers is dependent on the balance of various attractive and repulsive forces. Modulation of these forces allows critical physiological regulation of photosynthesis that provides efficient light-harvesting in limiting light but dissipation of excess potentially damaging radiation in saturating light. The light-harvesting complexes (LHCII) are central to this regulation, which is achieved by phosphorylation of stromal residues, protonation on the lumen surface and de-epoxidation of bound violaxanthin. The functional flexibility of LHCII derives from a remarkable pigment composition and configuration that not only allow efficient absorption of light and efficient energy transfer either to photosystem II or photosystem I core complexes, but through subtle configurational changes can also exhibit highly efficient dissipative reactions involving chlorophyll-xanthophyll and/or chlorophyll-chlorophyll interactions. These changes in function are determined at a macroscopic level by alterations in protein-protein interactions in the thylakoid membrane. The capacity and dynamics of this regulation are tuned to different physiological scenarios by the exact protein and pigment content of the light-harvesting system. Here, the molecular mechanisms involved will be reviewed, and the optimization of the light-harvesting system in different environmental conditions described.

  1. Mechanical properties identification and design optimization of nitinol shape memory alloy microactuators

    Science.gov (United States)

    Salehi, M.; Hamedi, M.; Salmani Nohouji, H.; Arghavani, J.

    2014-02-01

    Microactuators are essential elements of MEMS and are widely used in these devices. Microgrippers, micropositioners, microfixtures, micropumps and microvalves are well-known applications of microstructures. In this paper, the design optimization of shape memory alloy microactuators is discussed. Four different configurations of microactuator with variable geometrical parameters, generating different levels of displacement and force, are designed and analysed. In order to determine the optimum values of parameters for each microactuator, statistical design of experiments (DOE) is used. For this purpose, the Souza et al constitutive model (1988 Eur. J. Mech. A 17 789-806) is adapted for use in finite element analysis software. Mechanical properties of the SMA are identified by performing experimental tests on Ti-49.8%Ni. Finally, the specific energy of each microactuator is determined using the calibrated model and regression analysis. Moreover, the characteristic curve of each microactuator is obtained and with this virtual tool one can choose a microactuator with the desired force and displacement. The methodology discussed in this paper can be used as a reference to design appropriate microactuators for different MEMS applications producing various ranges of displacement and force.

  2. Nano-precipitation Strengthened G91 by Thermo-mechanical Treatment Optimization

    Science.gov (United States)

    Vivas, J.; Celada-Casero, C.; San Martín, D.; Serrano, M.; Urones-Garrote, E.; Adeva, P.; Aranda, M. M.; Capdevila, C.

    2016-11-01

    The increase of thermal efficiency in power plants has been the main driving force to develop Ferritic/Martensitic steels for structural applications capable of operating at 923 K (650 °C) and higher. It has been clarified in previous works that nano-sized precipitates and its distribution are the key factors controlling the stability of the microstructure at high operating temperatures. Based on the science of precipitate strengthening, the aim of this work is to optimize the thermo-mechanical treatment in a commercial creep-resistant steel (G91) to achieve a microstructure where MX precipitates present a suitable size and distribution. The alternative processing route proposed here allows gaining an increase up to 40 pct in yield strength at 973 K (700 °C) compared to the commercial steel. The results of small punch test carried out at room temperature showed that the improvement in strength was obtained without loss of ductility. This fact was attributed to a finer and more homogeneous dispersion of MX precipitates in comparison to the commercial steel.

  3. Optimization on condition of epigallocatechin-3-gallate (EGCG) nanoliposomes by response surface methodology and cellular uptake studies in Caco-2 cells

    Science.gov (United States)

    Luo, Xiaobo; Guan, Rongfa; Chen, Xiaoqiang; Tao, Miao; Ma, Jieqing; Zhao, Jin

    2014-06-01

    The major component in green tea polyphenols, epigallocatechin-3-gallate (EGCG), has been demonstrated to prevent carcinogenesis. To improve the effectiveness of EGCG, liposomes were used as a carrier in this study. Reverse-phase evaporation method besides response surface methodology is a simple, rapid, and beneficial approach for liposome preparation and optimization. The optimal preparation conditions were as follows: phosphatidylcholine-to-cholesterol ratio of 4.00, EGCG concentration of 4.88 mg/mL, Tween 80 concentration of 1.08 mg/mL, and rotary evaporation temperature of 34.51°C. Under these conditions, the experimental encapsulation efficiency and size of EGCG nanoliposomes were 85.79% ± 1.65% and 180 nm ± 4 nm, which were close with the predicted value. The malondialdehyde value and the release test in vitro indicated that the prepared EGCG nanoliposomes were stable and suitable for more widespread application. Furthermore, compared with free EGCG, encapsulation of EGCG enhanced its inhibitory effect on tumor cell viability at higher concentrations.

  4. Organizing and Economic Mechanism for Optimization of Industrial Structure in Electric Power Industry of the Republic of Belarus

    Directory of Open Access Journals (Sweden)

    S. G. Morozov

    2011-01-01

    Full Text Available The paper reveals economic peculiar features of innovative and investment processes in electric power industry. A scheme of organizing and economic mechanism for optimization of the industrial structure in the Belarusian electric power industry has been given in the paper. Realization of the mechanism will promote to better economic efficiency of power generation in the Belarusian power system and diversification of fuel balance of electric power industry.

  5. Reputation mechanism: From resolution for truthful online auctions to the model of optimal one-gambler problem

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory

    2009-01-01

    In this paper we study reputation mechanisms, and show how the notion of reputation can help us in building truthful online auction mechanisms. From the mechanism design prospective, we derive the conditions on and design a truthful online auction mechanism. Moreover, in the case when some agents may lay or cannot have the real knowledge about the other agents reputations, we derive the resolution of the auction, such that the mechanism is truthful. Consequently, we move forward to the optimal one-gambler/one-seller problem, and explain how that problem is refinement of the previously discussed online auction design in the presence of reputation mechanism. In the setting of the optimal one-gambler problem, we naturally rise and solve the specific question: What is an agent's optimal strategy, in order to maximize his revenue? We would like to stress that our analysis goes beyond the scope, which game theory usually discusses under the notion of reputation. We model one-player games, by introducing a new parameter (reputation), which helps us in predicting the agent's behavior, in real-world situations, such as, behavior of a gambler, real-estate dealer, etc.

  6. Optimization of the silk scaffold sericin removal process for retention of silk fibroin protein structure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Teh, Thomas K H; Toh, Siew-Lok; Goh, James C H, E-mail: dosgohj@nus.edu.s, E-mail: dostkh@nus.edu.s, E-mail: bietohsl@nus.edu.s [Division of Bioengineering, National University of Singapore (Singapore)

    2010-06-01

    In the process of removing sericin (degumming) from a raw silk scaffold, the fibroin structural integrity is often challenged, leading to mechanical depreciation. This study aims to identify the factors and conditions contributing to fibroin degradation during alkaline degumming and to perform an optimization study of the parameters involved to achieve preservation of fibroin structure and properties. The methodology involves degumming knitted silk scaffolds for various durations (5-90 min) and temperatures (60-100 {sup 0}C). Mechanical agitation and use of the refreshed solution during degumming are included to investigate how these factors contribute to degumming efficiency and fibroin preservation. Characterizations of silk fibroin morphology, mechanical properties and protein components are determined by scanning electron microscopy (SEM), single fiber tensile tests and gel electrophoresis (SDS-PAGE), respectively. Sericin removal is ascertained via SEM imaging and a protein fractionation method involving SDS-PAGE. The results show that fibroin fibrillation, leading to reduced mechanical integrity, is mainly caused by prolonged degumming duration. Through a series of optimization, knitted scaffolds are observed to be optimally degummed and experience negligible mechanical and structural degradation when subjected to alkaline degumming with mechanical agitation for 30 min at 100 {sup 0}C.

  7. Simplified Design and Optimization of Slotless Synchronous PM Machine for Micro-Satellite Electro-Mechanical Batteries

    Directory of Open Access Journals (Sweden)

    ABDI, B.

    2009-10-01

    Full Text Available Electro-mechanical batteries have important advantages as compared with chemical batteries, especially in low earth orbit satellites applications. High speed slotless external rotor permanent magnet machines are used in these systems as Motor/Generator. Proper material and structure for space applications are introduced. A simplified analytic design method is given for this type of machines. Finally, the optimization of machine in order to have maximum efficiency and minimum volume and weight are given in this paper. Particle swarm optimization is used as the optimization algorithm and the finite element-based simulations are used to confirm the design and optimization process and show less than 1.2% error in parametric design.

  8. Bioresorbable scaffolds for bone tissue engineering: optimal design, fabrication, mechanical testing and scale-size effects analysis.

    Science.gov (United States)

    Coelho, Pedro G; Hollister, Scott J; Flanagan, Colleen L; Fernandes, Paulo R

    2015-03-01

    Bone scaffolds for tissue regeneration require an optimal trade-off between biological and mechanical criteria. Optimal designs may be obtained using topology optimization (homogenization approach) and prototypes produced using additive manufacturing techniques. However, the process from design to manufacture remains a research challenge and will be a requirement of FDA design controls to engineering scaffolds. This work investigates how the design to manufacture chain affects the reproducibility of complex optimized design characteristics in the manufactured product. The design and prototypes are analyzed taking into account the computational assumptions and the final mechanical properties determined through mechanical tests. The scaffold is an assembly of unit-cells, and thus scale size effects on the mechanical response considering finite periodicity are investigated and compared with the predictions from the homogenization method which assumes in the limit infinitely repeated unit cells. Results show that a limited number of unit-cells (3-5 repeated on a side) introduce some scale-effects but the discrepancies are below 10%. Higher discrepancies are found when comparing the experimental data to numerical simulations due to differences between the manufactured and designed scaffold feature shapes and sizes as well as micro-porosities introduced by the manufacturing process. However good regression correlations (R(2) > 0.85) were found between numerical and experimental values, with slopes close to 1 for 2 out of 3 designs.

  9. Topology Optimization of Nano-Mechanical Cantilever Sensors Using a C0 Discontinuous Galerkin-Type Approach

    DEFF Research Database (Denmark)

    Marhadi, Kun Saptohartyadi; Evgrafov, Anton; Sørensen, Mads Peter

    2011-01-01

    We demonstrate the use of a C0 discontinuous Galerkin method for topology optimization of nano-mechanical sensors, namely temperature, surface stress, and mass sensors. The sensors are modeled using classical thin plate theory, which requires C1 basis functions in the standard finite element method...

  10. Zirconium/polyvinyl alcohol modified flat-sheet polyvinyldene fluoride membrane for decontamination of arsenic: Material design and optimization, study of mechanisms, and application prospects.

    Science.gov (United States)

    Zhao, Dandan; Yu, Yang; Chen, J Paul

    2016-07-01

    Arsenic contamination in industrial wastewater and groundwater has become an important environmental issue. In this study, a novel zirconium/polyvinyl alcohol (PVA) modified polyvinyldene fluoride (PVDF) membrane was developed for arsenate removal from simulated contaminated water. A PVDF flat-sheet membrane was first fabricated; it was then soaked in a zirconium-PVA solution and dried, and finally reacted with a glutaraldehyde solution, by which the zirconium ions were impregnated onto the PVDF surface through the ether and hydroxyl groups according to the cross-linkage mechanism. The fabrication procedure was optimized by the Box-Behnken experimental design approach. The adsorption kinetics study showed that most of uptake occurred in 5 h and the equilibrium was established in 24 h. The acidic condition was beneficial for the arsenate removal and the optimal removal efficiency can be obtained at pH 2.0. The experimental data of the adsorption isotherm was better described by Langmuir equation than Freundlich equation. The maximum adsorption capacity of 128 mg-As/g was achieved at pH 2.0. In the filtration study, the modified membrane with an area of 12.56 cm(2) could treat 15.6 L arsenate solution (equivalent to 75,150 bed volumes) with an influent concentration of 98.6 μg/L to meet the maximum contaminate level of 10 μg/L. Several instrumental studies revealed that the removal was mainly associated with ion exchange between chloride and arsenate ions.

  11. An optimal quality adaptation mechanism for end-to-end FGS video transmission

    Institute of Scientific and Technical Information of China (English)

    FENG Shun; ER Gui-hua; DAI Qiong-hai; LIU Ye-bin

    2006-01-01

    In this paper, we propose a novel optimal quality adaptation algorithm for MPEG-4 fine granular scalability (FGS)stream over wired network. Our algorithm can maximize perceptual video quality by minimizing video quality variation and increasing available bandwidth usage rate. Under the condition that the whole bandwidth evolution is known, we design an optimal algorithm to select layer. When the knowledge of future bandwidth is not available, we also develop an online algorithm based on the optimal algorithm. Simulation showed that both optimal algorithm and online algorithm can offer smoothed video quality evolution.

  12. Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms

    DEFF Research Database (Denmark)

    Niu, Shuli; Luo, Yiqi; Fei, Shenfeng

    2012-01-01

    It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. Here, we compiled data from 169 globally d...... ecosystem–climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models....... temperature) rather than changes in the temperature sensitivity of ecosystem respiration. Ecosystem‐level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate...

  13. Optimization of Operating Parameters for Minimum Mechanical Specific Energy in Drilling

    Energy Technology Data Exchange (ETDEWEB)

    Hamrick, Todd [West Virginia Univ., Morgantown, WV (United States)

    2011-01-01

    Efficiency in drilling is measured by Mechanical Specific Energy (MSE). MSE is the measure of the amount of energy input required to remove a unit volume of rock, expressed in units of energy input divided by volume removed. It can be expressed mathematically in terms of controllable parameters; Weight on Bit, Torque, Rate of Penetration, and RPM. It is well documented that minimizing MSE by optimizing controllable factors results in maximum Rate of Penetration. Current methods for computing MSE make it possible to minimize MSE in the field only through a trial-and-error process. This work makes it possible to compute the optimum drilling parameters that result in minimum MSE. The parameters that have been traditionally used to compute MSE are interdependent. Mathematical relationships between the parameters were established, and the conventional MSE equation was rewritten in terms of a single parameter, Weight on Bit, establishing a form that can be minimized mathematically. Once the optimum Weight on Bit was determined, the interdependent relationship that Weight on Bit has with Torque and Penetration per Revolution was used to determine optimum values for those parameters for a given drilling situation. The improved method was validated through laboratory experimentation and analysis of published data. Two rock types were subjected to four treatments each, and drilled in a controlled laboratory environment. The method was applied in each case, and the optimum parameters for minimum MSE were computed. The method demonstrated an accurate means to determine optimum drilling parameters of Weight on Bit, Torque, and Penetration per Revolution. A unique application of micro-cracking is also presented, which demonstrates that rock failure ahead of the bit is related to axial force more than to rotation speed.

  14. Design of a mechanical test to characterize sheet metals - Optimization using B-splines or cubic splines

    Science.gov (United States)

    Souto, Nelson; Thuillier, Sandrine; Andrade-Campos, A.

    2016-10-01

    Nowadays, full-field measurement methods are largely used to acquire the strain field developed by heterogeneous mechanical tests. Recent material parameters identification strategies based on a single heterogeneous test have been proposed considering that an inhomogeneous strain field can lead to a more complete mechanical characterization of the sheet metals. The purpose of this work is the design of a heterogeneous test promoting an enhanced mechanical behavior characterization of thin metallic sheets, under several strain paths and strain amplitudes. To achieve this goal, a design optimization strategy finding the appropriate specimen shape of the heterogeneous test by using either B-Splines or cubic splines was developed. The influence of using approximation or interpolation curves, respectively, was investigated in order to determine the most effective approach for achieving a better shape design. The optimization process is guided by an indicator criterion which evaluates, quantitatively, the strain field information provided by the mechanical test. Moreover, the design of the heterogeneous test is based on the resemblance with the experimental reality, since a rigid tool leading to uniaxial loading path is used for applying the displacement in a similar way as universal standard testing machines. The results obtained reveal that the optimization strategy using B-Splines curve approximation led to a heterogeneous test providing larger strain field information for characterizing the mechanical behavior of sheet metals.

  15. Modelling and optimization of seawater desalination process using mechanical vapour compression

    Directory of Open Access Journals (Sweden)

    V.P. Kravchenko

    2016-09-01

    Full Text Available In the conditions of global climate changes shortage of fresh water becomes an urgent problem for an increasing number of the countries. One of the most perspective technologies of a desalting of sea water is the mechanical vapour compression (MVC providing low energy consumption due to the principle of a heat pump. Aim: The aim of this research is to identify the reserves of efficiency increasing of the desalination systems based on mechanical vapour compression by optimization of the scheme and parameters of installations with MVC. Materials and Methods: The new type of desalination installation is offered which main element is the heat exchanger of the latent heat. Sea water after preliminary heating in heat exchangers comes to the evaporator-condenser where receives the main amount of heat from the condensed steam. A part of sea water evaporates, and the strong solution of salt (brine goes out of the evaporator, and after cooling is dumped back in the sea. The formed steam is compressed by the compressor and comes to the condenser. An essential singularity of this scheme is that condensation happens at higher temperature, than evaporation. Thanks to this the heat, which is comes out at devaporation, is used for evaporation of sea water. Thereby, in this class of desalination installations the principle of a heat pump is implemented. Results: For achievement of a goal the following tasks were solved: the mathematical model of installations with MVC is modified and supplemented; the scheme of heat exchangers switching is modified; influence of design data of desalination installation on the cost of an inventory and the electric power is investigated. The detailed analysis of the main schemes of installation and mathematical model allowed defining ways of decrease in energy consumption and the possible merit value. Influence of two key parameters - a specific power of the compressor and a specific surface area of the evaporator-condenser - on a

  16. Optimization of the diabetic nephropathy treatment with attention to the special features of cellular inflammation mechanisms

    Directory of Open Access Journals (Sweden)

    Тетяна Дмитрівна Щербань

    2016-02-01

    Full Text Available Aim. Optimization of the diabetic nephropathy (DN treatment in association with hypertonic disease (HD based on the study of neutrophil chain of pathogenic cellular mechanisms of these diseases development and the special features of its clinical course.Materials and methods. There were complexly examined 86 patients with HD associated with DN and 30 patients with isolated HD. The control group was formed by 30 practically healthy persons. The activity of NO-synthases in neutrophils was detected by Green colorimetric methods using Griess reagent. The expression of ІСАМ-1 (CD54, CD11b-integrin and inducible NO-synthase on neutrophils was detected by the indirect immunocytochemical method. Oxygen-depending activity of neutrophils was assessed in NBT-test.Results. Expression of adhesive molecules of CD54and CD11b-integrin on neutrophils of peripheral blood essentially increases (р <0,001 in patients with DN in association with HD comparing with isolated HD and the control group.At associated pathology on the background of high oxygen-depending activity of neutrophils its functional reserve decreases that results in intensification of inflammatory processes in kidneys (р<0,001.In comorbid patients chronization of pathological process results in imbalance of NO-synthases system in neutrophils: on the background of decrease of activity of constituent NO-synthases the expression and activity of inducible NO-synthase increase (р<0,001 .The use of L-arginine hydrochloride in the complex therapy of patients with DN associated with HD intensifies organoprotective effect of basal therapy, results in facilitation of the clinical course, decreases albuminuria, corrects the functional indices of neutrophils and diminishes imbalance in NO-synthases system.Conclusions. In patients with DN in association with HD the neutrophil chain of cellular inflammation mechanisms are activated: expression of adhesive molecules grows, oxygen-depending metabolism is

  17. Basic Knowledge for Market Principle: Approaches to the Price Coordination Mechanism by Using Optimization Theory and Algorithm

    Science.gov (United States)

    Aiyoshi, Eitaro; Masuda, Kazuaki

    On the basis of market fundamentalism, new types of social systems with the market mechanism such as electricity trading markets and carbon dioxide (CO2) emission trading markets have been developed. However, there are few textbooks in science and technology which present the explanation that Lagrange multipliers can be interpreted as market prices. This tutorial paper explains that (1) the steepest descent method for dual problems in optimization, and (2) Gauss-Seidel method for solving the stationary conditions of Lagrange problems with market principles, can formulate the mechanism of market pricing, which works even in the information-oriented modern society. The authors expect readers to acquire basic knowledge on optimization theory and algorithms related to economics and to utilize them for designing the mechanism of more complicated markets.

  18. Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms

    NARCIS (Netherlands)

    Niu, S.; Luo, Y.; Fei, S.; Yuan, W.; Schimel, D.; Law, B.E.; Ammann, C.; Moors, E.J.

    2012-01-01

    It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally di

  19. Mechanical Characterization and Shape Optimization of Fascicle-Like 3D Skeletal Muscle Tissues Contracted with Electrical and Optical Stimuli.

    Science.gov (United States)

    Neal, Devin; Sakar, Mahmut Selman; Bashir, Rashid; Chan, Vincent; Asada, Haruhiko Harry

    2015-06-01

    In this study, we present a quantitative approach to construct effective 3D muscle tissues through shape optimization and load impedance matching with electrical and optical stimulation. We have constructed long, thin, fascicle-like skeletal muscle tissue and optimized its form factor through mechanical characterization. A new apparatus was designed and built, which allowed us to measure force-displacement characteristics with diverse load stiffnesses. We have found that (1) there is an optimal form factor that maximizes the muscle stress, (2) the energy transmitted to the load can be maximized with matched load stiffness, and (3) optical stimulation using channelrhodopsin2 in the muscle tissue can generate a twitch force as large as its electrical counterpart for well-developed muscle tissue. Using our tissue construct method, we found that an optimal initial diameter of 500 μm outperformed tissues using 250 μm by more than 60% and tissues using 760 μm by 105%. Using optimal load stiffness, our tissues have generated 12 pJ of energy per twitch at a peak generated stress of 1.28 kPa. Additionally, the difference in optically stimulated twitch performance versus electrically stimulated is a function of how well the overall tissue performs, with average or better performing strips having less than 10% difference. The unique mechanical characterization method used is generalizable to diverse load conditions and will be used to match load impedance to muscle tissue impedance for a wide variety of applications.

  20. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... Uptake? A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) ... of thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that ...

  1. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... limitations of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan ... tissues in your body. top of page How is the procedure performed? Nuclear medicine imaging is usually ...

  2. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... Uptake? A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) ... of thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that ...

  3. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is ... code: Phone no: Thank you! Do you have a personal story about radiology? Share your patient story ...

  4. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... known as a thyroid uptake. It is a measurement of thyroid function, but does not involve imaging. ... eating can affect the accuracy of the uptake measurement. Jewelry and other metallic accessories should be left ...

  5. Adjusting ammonium uptake via phosphorylation.

    Science.gov (United States)

    Lanquar, Viviane; Frommer, Wolf B

    2010-06-01

    In plants, AMT/MEP/Rh superfamily mediates high affinity ammonium uptake. AMT/MEP transporters form a trimeric complex, which requires a productive interaction between subunits in order to be functional. The AMT/MEP C-terminal domain is highly conserved in more than 700 AMT homologs from cyanobacteria to higher plants with no cases found to be lacking this domain. AMT1;1 exists in active and inactive states, probably controlled by the spatial positioning of the C-terminus. Ammonium triggers the phosphorylation of a conserved threonine residue (T460) in the C-terminus of AMT1;1 in a time- and concentration-dependent manner. The T460 phosphorylation level correlates with a decrease of root ammonium uptake. We propose that ammonium-induced phosphorylation modulates ammonium uptake as a general mechanism to protect against ammonium toxicity.

  6. Growth Mechanism and Optimized Parameters to Synthesize Nation-115 Nanowire Arrays with Anodic Aluminium Oxide Membranes as Templates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lu; PAN Cao-Feng; ZHU Jing

    2008-01-01

    @@ Nafion-115 nanowire arrays are synthesized with an extrusion method using AAO membranes as templates. It is indicated that the vacuum treating of AAO templates before surface decoration plays an important role in obtaining high filling rate of the Nafion-115 nanowires in the AAO templates, while the concentration of Nafion-115 DMSO solutions does not affect the filling rate greatly. The optimized parameters to synthesize the Nafion-115 nanowire arrays are studied. The filling rate of the Nafion-115 nanowires in the AAO templates synthesized with the optimized parameters is about 95%. The growth mechanism of Nafion-115 nanowires is discussed to qualitatively explain the experimental results.

  7. DNA UPTAKE BY TRANSFORMABLE BACTERIA

    Energy Technology Data Exchange (ETDEWEB)

    LACKS,S.A.

    1999-09-07

    The various processes of DNA uptake by cells can be categorized as: viral DNA entry, conjugation, or transformation. Within each category, a variety of mechanisms have been found. However, considerable similarities occur among the different mechanisms of conjugation and, especially, transformation. All of these natural mechanisms of DNA transfer are quite elaborate and involve multiple protein components, as the case may be, of the virus, the donor cell, and the recipient cell. The mechanisms of viral infection and conjugation will be discussed mainly with respect to their relevance to transformation.

  8. DNA Uptake by Transformable Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Lacks, Sanford A.

    1999-03-31

    The various processes of DNA uptake by cells can be categorized as: viral DNA entry, conjugation, or transformation. Within each category, a variety of mechanisms have been found. However, considerable similarities occur among the different mechanisms of conjugation and, especially, transformation. All of these natural mechanisms of DNA transfer are quite elaborate and involve multiple protein components, as the case may be, of the virus, the donor cell, and the recipient cell. The mechanisms of viral infection and conjugation will be discussed mainly with respect to their relevance to transformation.

  9. Kinematics analysis and optimization of the fast shearing-extrusion joining mechanism for solid-state metal

    Science.gov (United States)

    Zhang, Shuangjie; Yao, Yunfeng; Li, Lingchong; Wang, Lijuan; Li, Junxia; Li, Qiang

    2015-11-01

    Dynamical Joining of the solid-state metal is the key technology to realize endless hot rolling. The heating and laser welding method both require long joining time. Based on super deformation method, a 7-bar and 2-slider mechanism was developed in Japan, and the joining time is less than 0.5 s, however the length of each bar are not reported and this mechanism is complex. A relatively simple 6-bar and 1-slider mechanism is put forward, which can realize the shearing and extrusion motion of the top and bottom blades with a speed approximately equal to the speed of the metal plates. In order to study the kinematics property of the double blades, based on complex vector method, the multi-rigid-body model is built, and the displacement and speed functions of the double blades, the joining time and joining thickness are deduced, the kinematics analysis shows that the initial parameters can't satisfy the joining process. Hence, optimization of this mechanism is employed using genetic algorithm(GA) and the optimization parameters of this mechanism are obtained, the kinematics analysis show that the joining time is less than 0.1 s, the joining thickness is more than 80% of the thickness of the solid-state metal, and the horizontal speeds of the blades are improved. A new mechanism is provided for the joining of the solid-state metal and a foundation is laid for the design of the device.

  10. Kinematics Analysis and Optimization of the Fast Shearing-extrusion Joining Mechanism for Solid-state Metal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuangjie; YAO Yunfeng; LI Lingchong; WANG Lijuan; LI Junxia; LI Qiang

    2015-01-01

    Dynamical Joining of the solid-state metal is the key technology to realize endless hot rolling. The heating and laser welding method both require long joining time. Based on super deformation method, a 7-bar and 2-slider mechanism was developed in Japan, and the joining time is less than 0.5 s, however the length of each bar are not reported and this mechanism is complex. A relatively simple 6-bar and 1-slider mechanism is put forward, which can realize the shearing and extrusion motion of the top and bottom blades with a speed approximately equal to the speed of the metal plates. In order to study the kinematics property of the double blades, based on complex vector method, the multi-rigid-body model is built, and the displacement and speed functions of the double blades, the joining time and joining thickness are deduced, the kinematics analysis shows that the initial parameters can’t satisfy the joining process. Hence, optimization of this mechanism is employed using genetic algorithm(GA) and the optimization parameters of this mechanism are obtained, the kinematics analysis show that the joining time is less than 0.1 s, the joining thickness is more than 80% of the thickness of the solid-state metal, and the horizontal speeds of the blades are improved. A new mechanism is provided for the joining of the solid-state metal and a foundation is laid for the design of the device.

  11. Tailoring Macroscale Response of Mechanical and Heat Transfer Systems by Topology Optimization of Microstructural Details

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Lazarov, Boyan Stefanov

    2015-01-01

    -contrast material parameters is proposed to alleviate the high computational cost associated with solving the discrete systems arising during the topology optimization process. Problems within important engineering areas, heat transfer and linear elasticity, are considered for exemplifying the approach...

  12. Skeletal muscle glucose uptake during exercise

    DEFF Research Database (Denmark)

    Rose, Adam John; Richter, Erik A.

    2005-01-01

    The increase in skeletal muscle glucose uptake during exercise results from a coordinated increase in rates of glucose delivery (higher capillary perfusion), surface membrane glucose transport, and intracellular substrate flux through glycolysis. The mechanism behind the movement of GLUT4...

  13. Phase Transitions in Combinatorial Optimization Problems Basics, Algorithms and Statistical Mechanics

    CERN Document Server

    Hartmann, Alexander K

    2005-01-01

    A concise, comprehensive introduction to the topic of statistical physics of combinatorial optimization, bringing together theoretical concepts and algorithms from computer science with analytical methods from physics. The result bridges the gap between statistical physics and combinatorial optimization, investigating problems taken from theoretical computing, such as the vertex-cover problem, with the concepts and methods of theoretical physics. The authors cover rapid developments and analytical methods that are both extremely complex and spread by word-of-mouth, providing all the necessary

  14. Bacterial foraging-optimized PID control of a two-wheeled machine with a two-directional handling mechanism.

    Science.gov (United States)

    Goher, K M; Fadlallah, S O

    2017-01-01

    This paper presents the performance of utilizing a bacterial foraging optimization algorithm on a PID control scheme for controlling a five DOF two-wheeled robotic machine with two-directional handling mechanism. The system under investigation provides solutions for industrial robotic applications that require a limited-space working environment. The system nonlinear mathematical model, derived using Lagrangian modeling approach, is simulated in MATLAB/Simulink(®) environment. Bacterial foraging-optimized PID control with decoupled nature is designed and implemented. Various working scenarios with multiple initial conditions are used to test the robustness and the system performance. Simulation results revealed the effectiveness of the bacterial foraging-optimized PID control method in improving the system performance compared to the PID control scheme.

  15. Influencing Factors of Thermal Deformation on Hydrostatic Pressure Mechanical Seal and Optimization of Rotating and Stationary Rings

    Directory of Open Access Journals (Sweden)

    Lin Dong

    2013-02-01

    Full Text Available According to thermo-elastic deformation theory, take the temperature field analysis results of hydrostatic pressure mechanical seal as volume load to resolve the problem of thermal-structure coupling deformation of rotating and stationary rings in ANSYS software. The distribution laws of thermal strain, thermal stress and thermal-structure coupling deformation are obtained. The effects of working, material and structural parameters on axial, radial thermal deformation and deformation taper of the end faces are discussed in detail, and the main affecting factors are found out. Measures and structural constraint programs to control the thermal deformation are put forward. Base on the theory of thermal deformation compensation, the rotating and stationary rings are optimized, and the thermal deformation before and after their optimization are solved respectively and analyzed comparatively to verify the feasibility of the optimization program.

  16. Design of articulated mechanisms with a degree of freedom constraint using global optimization

    DEFF Research Database (Denmark)

    Kawamoto, Atsushi; Stolpe, Mathias

    2004-01-01

    This paper deals with design of articulated mechanisms using a truss ground structure representation. The considered mechanism design problem is to maximize the output displacement for a given input force by choosing a prescribed number of truss elements out of all the available elements, so...... that the resultant mechanism has one mechanical degree of freedom when supported in a statically determinate manner. The mechanical degree of freedom constraint is included since it is essential for obtaining a proper articulated mechanism design. The Green-Lagrange strain measure is used to accommodate for large...

  17. Identification of a Pro-Angiogenic Potential and Cellular Uptake Mechanism of a LMW Highly Sulfated Fraction of Fucoidan from Ascophyllum nodosum

    Science.gov (United States)

    Marinval, Nicolas; Saboural, Pierre; Haddad, Oualid; Maire, Murielle; Bassand, Kevin; Geinguenaud, Frederic; Djaker, Nadia; Ben Akrout, Khadija; Lamy de la Chapelle, Marc; Robert, Romain; Oudar, Olivier; Guyot, Erwan; Laguillier-Morizot, Christelle; Sutton, Angela; Chauvierre, Cedric; Chaubet, Frederic; Charnaux, Nathalie; Hlawaty, Hanna

    2016-01-01

    Herein we investigate the structure/function relationships of fucoidans from Ascophyllum nodosum to analyze their pro-angiogenic effect and cellular uptake in native and glycosaminoglycan-free (GAG-free) human endothelial cells (HUVECs). Fucoidans are marine sulfated polysaccharides, which act as glycosaminoglycans mimetics. We hypothesized that the size and sulfation rate of fucoidans influence their ability to induce pro-angiogenic processes independently of GAGs. We collected two fractions of fucoidans, Low and Medium Molecular Weight Fucoidan (LMWF and MMWF, respectively) by size exclusion chromatography and characterized their composition (sulfate, fucose and uronic acid) by colorimetric measurement and Raman and FT-IR spectroscopy. The high affinities of fractionated fucoidans to heparin binding proteins were confirmed by Surface Plasmon Resonance. We evidenced that LMWF has a higher pro-angiogenic (2D-angiogenesis on Matrigel) and pro-migratory (Boyden chamber) potential on HUVECs, compared to MMWF. Interestingly, in a GAG-free HUVECs model, LMWF kept a pro-angiogenic potential. Finally, to evaluate the association of LMWF-induced biological effects and its cellular uptake, we analyzed by confocal microscopy the GAGs involvement in the internalization of a fluorescent LMWF. The fluorescent LMWF was mainly internalized through HUVEC clathrin-dependent endocytosis in which GAGs were partially involved. In conclusion, a better characterization of the relationships between the fucoidan structure and its pro-angiogenic potential in GAG-free endothelial cells was required to identify an adapted fucoidan to enhance vascular repair in ischemia. PMID:27763505

  18. Identification of a Pro-Angiogenic Potential and Cellular Uptake Mechanism of a LMW Highly Sulfated Fraction of Fucoidan from Ascophyllum nodosum

    Directory of Open Access Journals (Sweden)

    Nicolas Marinval

    2016-10-01

    Full Text Available Herein we investigate the structure/function relationships of fucoidans from Ascophyllum nodosum to analyze their pro-angiogenic effect and cellular uptake in native and glycosaminoglycan-free (GAG-free human endothelial cells (HUVECs. Fucoidans are marine sulfated polysaccharides, which act as glycosaminoglycans mimetics. We hypothesized that the size and sulfation rate of fucoidans influence their ability to induce pro-angiogenic processes independently of GAGs. We collected two fractions of fucoidans, Low and Medium Molecular Weight Fucoidan (LMWF and MMWF, respectively by size exclusion chromatography and characterized their composition (sulfate, fucose and uronic acid by colorimetric measurement and Raman and FT-IR spectroscopy. The high affinities of fractionated fucoidans to heparin binding proteins were confirmed by Surface Plasmon Resonance. We evidenced that LMWF has a higher pro-angiogenic (2D-angiogenesis on Matrigel and pro-migratory (Boyden chamber potential on HUVECs, compared to MMWF. Interestingly, in a GAG-free HUVECs model, LMWF kept a pro-angiogenic potential. Finally, to evaluate the association of LMWF-induced biological effects and its cellular uptake, we analyzed by confocal microscopy the GAGs involvement in the internalization of a fluorescent LMWF. The fluorescent LMWF was mainly internalized through HUVEC clathrin-dependent endocytosis in which GAGs were partially involved. In conclusion, a better characterization of the relationships between the fucoidan structure and its pro-angiogenic potential in GAG-free endothelial cells was required to identify an adapted fucoidan to enhance vascular repair in ischemia.

  19. The Optimization Model for Interregional Power System Planning considering Carbon Emissions Trading and Renewable Energy Quota Mechanism

    Directory of Open Access Journals (Sweden)

    Liwei Ju

    2016-01-01

    Full Text Available In China, the rapid construction of ultra-high-voltage (UHV transmission lines promotes interregional resource optimizing configuration and interregional power system planning. This paper analyzes external environment of interregional power system planning from geographical, technical, and policy environments. Then, the paper takes the minimum system investment cost as the optimization objective and constructs the optimization model of interregional power system planning considering carbon emissions trading (CET and renewable energy quota mechanism (REQ. Finally, this paper sets base scenario, carbon emissions trading scenario, renewable energy quota mechanism scenario, and comprehensive scenario for case simulation. The results show that interregional power system planning could connect power grids in different regions, enlarge wind power consumption space, and relieve the inconformity problem between power resource and load demand. CET and REQ can increase the installed proportion of clean energy and reduce carbon dioxide emissions, but the cost of transmission lines construction and system reserve will increase correspondingly. The optimization effect of REQ on power system planning is better than CET. When they are both introduced, the power structure will reach the best, carbon dioxide emissions will achieve the minimum, and comprehensive benefits will become more balanced.

  20. An integrative view of mechanisms underlying generalized spike-and-wave epileptic seizures and its implication on optimal therapeutic treatments.

    Directory of Open Access Journals (Sweden)

    Boyuan Yan

    Full Text Available Many types of epileptic seizures are characterized by generalized spike-and-wave discharges. In the past, notable effort has been devoted to understanding seizure dynamics and various hypotheses have been proposed to explain the underlying mechanisms. In this paper, by taking an integrative view of the underlying mechanisms, we demonstrate that epileptic seizures can be generated by many different combinations of synaptic strengths and intrinsic membrane properties. This integrative view has important medical implications: the specific state of a patient characterized by a set of biophysical characteristics ultimately determines the optimal therapeutic treatment. Through the same view, we further demonstrate the potentiation effect of rational polypharmacy in the treatment of epilepsy and provide a new angle to resolve the debate on polypharmacy. Our results underscore the need for personalized medicine and demonstrate that computer modeling and simulation may play an important role in assisting the clinicians in selecting the optimal treatment on an individual basis.

  1. 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.

  2. An Optimal Design of Driving Mechanism in a 1 Degree of Freedom (d.o.f. Anthropomorphic Finger

    Directory of Open Access Journals (Sweden)

    M. Ceccarelli

    2005-01-01

    Full Text Available Mechanisms can be used in finger design to obtain suitable actuation systems and to give stiff robust behavior in grasping tasks. The design of driving mechanisms for fingers has been attached at LARM in Cassino with the aim to obtain one degree of freedom actuation for an anthropomorphic finger. The dimensional design of a finger-driving mechanism has been formulated as a multi-objective optimization problem by using evaluation criteria for fundamental characteristics regarding with finger motion, grasping equilibrium and force transmission. The feasibility of the herein proposed optimum design procedure for a finger-driving mechanism has been tested by numerical examples that have been also used to enhance a prototype previously built at LARM in Cassino.

  3. Effect of optimal aging treatment on magnetic performance and mechanical properties of sintered Nd-Fe-B permanent magnets

    Institute of Scientific and Technical Information of China (English)

    DING Xia; DING Kai-hong; CUI Sheng-li; SUN Yong-cong; LI Mu-sen

    2016-01-01

    The magnetic performance and mechanical properties including hardness, brittleness, fracture toughness and strength characteristics of the as-sintered and the optimal aged Nd-Fe-B magnets were examined in this work. A new method of Vickers hardness indentation combined with acoustic emission was used to test the brittleness of the magnets.The results show that the magnetic properties of the magnets could be improved through aging treatment, especially the intrinsic coercive force. But it is accompanied by a decrease of strength and fracture toughness. Theoretical calculation confirms that acoustic emission energy accumulated count value could be used to characterize the material brittleness. The bending fracture morphologies of the as-sintered and the optimal aged NdFeB magnets were investigated with the emphasis on the relationship between mechanical properties and microstructure using a field emission scanning electron microscopy (FE-SEM). The research results indicate that the intergranular fracture is the primary fracture mechanism for both as-sintered and optimal aged NdFeB magnets. Aging treatment changes the morphology and distribution of the Nd-rich phases, reducing the sliding resistance between Nd2Fe14B main crystal grains and lowers the grain boundary strength, which is the main reason for the strength and fracture toughness decrease of the aged Nd-Fe-B magnets.

  4. 植物吸收、迁移和代谢有机污染物的机理及影响因素%Uptake, Translocation and Metabolism of Organic Pollutants by Plants: Mechanisms and Affecting Factors

    Institute of Scientific and Technical Information of China (English)

    林庆祺; 蔡信德; 王诗忠; 杨秀虹; 仇荣亮; 黄雄飞; 周文

    2013-01-01

    植物对有机污染物在环境中的归趋行为具有重要影响.分析了植物吸收、迁移和代谢有机污染物的相关机理,重点介绍了植物根部和地上部对有机污染物吸收的过程及规律,指出利用脂质-水分配系数(Klip)代替辛醇-水分配系数(Kow),以及考虑植物碳水化合物的影响,可以更准确地评价植物对有机污染物的吸收能力;探讨了利用蒸腾流浓度因子(Transpiration stream concentration factor,TSCF)指示有机污染物从根部往地上部迁移能力的可行性及其相关研究进展;简要介绍了有机污染物在植物细胞内的代谢过程及所涉及的酶系;进而从加强吸收机理研究、考虑有机污染物的代谢和毒性、完善预测模型构建等方面对该研究领域进行了展望.%Higher plants hold an important impact on the fates of organic pollutants in the environment.Plant uptake,accumulation and metabolism are key processes that affect movement and transformation of organic pollutants.In this paper,current progress on the main mechanisms of plant uptake,translocation and metabolism of organic pollutants was reviewed,with particular emphasis on uptake pathways by both roots and shoots.We pointed out that the use of lipid-water partition coefficient(Klip) instead of octanol-water partition coefficient (Kow) would give a more accurate evaluation on the uptake ability of plants,when the effects of plant carbonhydrate were concerned as well.Results from a new observation technology namely Two-photon excitation microscopy(TPEM) suggested that apoplastic movement might be the dominant pathway for uptake of organic pollutants,especially for the highly hydrophobic ones.The feasibility of using transpiration stream concentration factor(TSCF) as an indicator of organic pollutants translocation from root to shoot was discussed.Although high translocation ability of moderately hydrophobic organic pollutants was mostly reported,new evidence indicated

  5. Effect and mechanism of carbon sources on phosphorus uptake by microorganisms in sequencing batch reactors with the single-stage oxic process

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    To investigate the chief reason for phosphorus uptake by microorganisms affected by substrates in sequencing batch reactors with the single-stage oxic process,two typical substrates,glucose (R1) and acetate (R2) were used as the sole carbon source,and the performances of phosphorus removal and the changes of intracellular storage were compared. The experimental results showed that the phenomenon of excess phosphorus uptake was observed in two reactors,but bacteria’s capability to take in phosphorus and its intracellular storage were obviously different under the same operational condition. After steady-state operation,total phosphorus (TP) removed per MLVSS in R1 and R2 was 6.7―7.4 and 2.7―3.2 mg/g,respectively. The energy storage of poly-β-hydroxyalkanoates (PHA) was nearly constant in R1 during the whole period,and another aerobic storage of glycogen was accumulated (the max accumulation of glycogen was 3.21 mmol-C/g) when external substrate was consumed,and then was decreased to the initial level. However in R2,PHA and glycogen were both accumulated (2.1 and 0.55 mmol-C/g,respectively) when external substrate was consumed,but they showed different changes after the period of external consumption. Compared to rapid decrease of PHA to the initial level,glycogen continued accumulating to the peak (0.88 mmol-C/g) in 2 h of aeration before decreasing. During the aeration,the accumulations/transformations of internal carbon sources in R1 were higher than those in R2. In addition,obvious TP releases were both observed in R1 and R2 other than PHA and glycogen during the long-term idle period; moreover,the release content of phosphorus in R1 was also higher than that in R2. The researches indicated that different aerobic metabolism of substrate occurred in R1 and R2 due to the different carbon sources in influent,resulting in different types and contents of aerobic storage accumulated/translated in bacteria of R1 and R2. As a result,ATP content provided for

  6. Analysis and Improvement of TCP Congestion Control Mechanism Based on Global Optimization Model

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Network flow control is formulated as a global optimization problem of user profit. A general global optimization flow control model is established. This model combined with the stochastic model of TCP is used to study the global rate allocation characteristic of TCP. Analysis shows when active queue manage ment is used in network TCP rates tend to be allocated to maximize the aggregate of a user utility function Us (called Us fairness). The TCP throughput formula is derived. An improved TCP congestion control mecha nism is proposed. Simulations show its throughput is TCP friendly when competing with existing TCP and its rate change is smoother. Therefore, it is suitable to carry multimedia applications.

  7. Macroscopic root water uptake distribution using a matric flux potential approach

    NARCIS (Netherlands)

    Jong van Lier, de Q.; Dam, van J.C.; Metselaar, K.; Jong, de R.; Duijnisveld, W.H.M.

    2008-01-01

    Hydrological models featuring root water uptake usually do not include compensation mechanisms such that reductions in uptake from dry layers are compensated by an increase in uptake from wetter layers. We developed a physically based root water uptake model with an implicit compensation mechanism.<

  8. Macroscopic root water uptake distribution using a matric flux potential approach

    NARCIS (Netherlands)

    Jong van Lier, de Q.; Dam, van J.C.; Metselaar, K.; Jong, de R.; Duijnisveld, W.H.M.

    2008-01-01

    Hydrological models featuring root water uptake usually do not include compensation mechanisms such that reductions in uptake from dry layers are compensated by an increase in uptake from wetter layers. We developed a physically based root water uptake model with an implicit compensation mechanism.<

  9. Modeling the capture rate by a radially oscillating spherical bubble. A bio-mimetic model for studying the mechanically-mediated uptake by cells

    Science.gov (United States)

    Raudino, Antonio; Raciti, Domenica; Grassi, Antonio

    2016-11-01

    The surface of living cells constitutes a dynamic environment submitted to complex oscillatory motions. Oscillations may modify the uptake of incoming molecules. In this study we explored a bio-mimetic system formed by oscillating bubbles suspended in a sea of randomly distributed diffusants. We investigated by a time-dependent Fokker-Planck equation the effect of the periodic motions on the adsorption of a diffusant onto the moving bubble surface. We introduced both direct interactions between the diffusant and the fluctuating surface and indirect interactions due to the hydrodynamic motions around a vibrating surface. Results are expressed in terms of oscillation frequencies and amplitudes. An overall reduction of the bound diffusant at the bubble surface was observed.

  10. Structural optimization of nanostructured aluminum for enhancing mechanical properties and formability

    DEFF Research Database (Denmark)

    Kidmose, Jacob

    The aim of this project is i) to optimize processing parameters of accumulative roll bonding (ARB) to produce a nanostructure of a commercial pure aluminium (Al1050), ii) to apply post-ARB process treatments in the form of thermal annealing or plastic deformation to tailor the structure and mecha...

  11. Statistical mechanics of the inverse Ising problem and the optimal objective function

    Science.gov (United States)

    Berg, Johannes

    2017-08-01

    The inverse Ising problem seeks to reconstruct the parameters of an Ising Hamiltonian on the basis of spin configurations sampled from the Boltzmann measure. Over the last decade, many applications of the inverse Ising problem have arisen, driven by the advent of large-scale data across different scientific disciplines. Recently, strategies to solve the inverse Ising problem based on convex optimisation have proven to be very successful. These approaches maximise particular objective functions with respect to the model parameters. Examples are the pseudolikelihood method and interaction screening. In this paper, we establish a link between approaches to the inverse Ising problem based on convex optimisation and the statistical physics of disordered systems. We characterise the performance of an arbitrary objective function and calculate the objective function which optimally reconstructs the model parameters. We evaluate the optimal objective function within a replica-symmetric ansatz and compare the results of the optimal objective function with other reconstruction methods. Apart from giving a theoretical underpinning to solving the inverse Ising problem by convex optimisation, the optimal objective function outperforms state-of-the-art methods, albeit by a small margin.

  12. A Multi-objective Optimization Application in Friction Stir Welding: Considering Thermo-mechanical Aspects

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2010-01-01

    speed and traverse welding speed have been sought in order to achieve the goals mentioned above using an evolutionary multi-objective optimization (MOO) algorithm, i.e. non-dominated sorting genetic algorithm (NSGA-II), integrated with a transient, 2-dimensional sequentially coupled thermomechanical...

  13. HYBRID OPTIMIZING GRIFFON-VULTURE ALGORITHM BASED ON SWARM INTELLIGENCE MECHANISMS

    Directory of Open Access Journals (Sweden)

    Chastikova V. A.

    2014-06-01

    Full Text Available Griffon-vultures with input parameters minimal value for compound functions optimization that change during the time searching hybrid algorithm offered in this article. Researches of its efficiency and comparing analysis with some other systems have been performed

  14. Two-Swim Operators in the Modified Bacterial Foraging Algorithm for the Optimal Synthesis of Four-Bar Mechanisms

    Directory of Open Access Journals (Sweden)

    Betania Hernández-Ocaña

    2016-01-01

    Full Text Available This paper presents two-swim operators to be added to the chemotaxis process of the modified bacterial foraging optimization algorithm to solve three instances of the synthesis of four-bar planar mechanisms. One swim favors exploration while the second one promotes fine movements in the neighborhood of each bacterium. The combined effect of the new operators looks to increase the production of better solutions during the search. As a consequence, the ability of the algorithm to escape from local optimum solutions is enhanced. The algorithm is tested through four experiments and its results are compared against two BFOA-based algorithms and also against a differential evolution algorithm designed for mechanical design problems. The overall results indicate that the proposed algorithm outperforms other BFOA-based approaches and finds highly competitive mechanisms, with a single set of parameter values and with less evaluations in the first synthesis problem, with respect to those mechanisms obtained by the differential evolution algorithm, which needed a parameter fine-tuning process for each optimization problem.

  15. Are geometrical and structural variations along the length of the aorta governed by a principle of "optimal mechanical operation"?

    Science.gov (United States)

    Rachev, Alexander; Greenwald, Stephen; Shazly, Tarek

    2013-08-01

    It is well-documented that the geometrical dimensions, the longitudinal stretch ratio in situ, certain structural mechanical descriptors such as compliance and pressure-diameter moduli, as well as the mass fractions of structural constituents, vary along the length of the descending aorta. The origins of and possible interrelations among these observed variations remain open questions. The central premise of this study is that having considered the variation of the deformed inner diameter, axial stretch ratio, and area compliance along the aorta to be governed by the systemic requirements for flow distribution and reduction of cardiac preload, the zero-stress state geometry and mass fractions of the basic structural constituents of aortic tissue meet a principle of optimal mechanical operation. The principle manifests as a uniform distribution of the circumferential stress in the aortic wall that ensures effective bearing of the physiological load and a favorable mechanical environment for mechanosensitive vascular smooth muscle cells. A mathematical model is proposed and inverse boundary value problems are solved for the equations that follow from finite elasticity, structure-based constitutive modeling within constrained mixture theory, and stress-induced control of aortic homeostasis, mediated by the synthetic activity of vascular smooth muscle cells. Published experimental data are used to illustrate the predictive power of the proposed model. The results obtained are in agreement with published experimental data and support the proposed principle of optimal mechanical operation for the descending aorta.

  16. {sup 18}F-FDG uptake at the surgical margin after hepatic resection: Patterns of uptake and differential diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Peungjesada, Silanath [University New Mexico, Department of Radiology, Albuquerque, NM (United States); Aloia, Thomas A. [University of Texas MD Anderson Cancer Center, Department of Surgical Oncology, Unit 444, Houston, TX (United States); Fox, Patricia [University of Texas MD Anderson Cancer Center, Department of Biostatistics, Unit 1411, Houston, TX (United States); Chasen, Beth [University of Texas MD Anderson Cancer Center, Department of Nuclear Medicine, Unit 1483, Houston, TX (United States); Shin, Sooyoung; Loyer, Evelyne M. [University of Texas MD Anderson Cancer Center, Department of Diagnostic Radiology, Unit 1473, Houston, TX (United States); Baiomy, Ali [Cairo University, National Cancer Center, Cairo (Egypt)

    2015-08-15

    To evaluate the patterns of {sup 18}F-FDG uptake at the surgical margin after hepatectomy to identify features that may differentiate benign and malignant uptake. Patients who had undergone a PET/CT after hepatectomy were identified. Delay between resection and PET/CT, presence of uptake at the surgical margin, pattern of uptake, and maximal standardized value were recorded. The PET/CT findings were correlated with contrast-enhanced CT or MRI. There were 26 patients with increased 18F-FDG uptake; uptake was diffuse in seven and focal in 19. Diffuse uptake was due to inflammation in all cases. Focal uptake was due to recurrence in 12 and inflammation in seven cases. Defining a focal pattern only as a positive for malignancy yielded 100 % sensitivity, 87 % specificity, 37 % false positive rate. As expected, SUV{sub max} was significantly higher for recurrence than inflammation, but did overlap. Contrast-enhanced CT allowed differentiation between malignant and benign uptake in all cases. F-FDG uptake after hepatectomy does not equate to recurrence and yields a high false positive rate. Diffuse uptake did not require additional evaluation in our sample. Focal uptake, however, may be due to recurrence; differentiating benign and malignant nodular uptake relies on optimal contrast-enhanced CT or MRI. (orig.)

  17. Enhancement of CO2 sorption uptake on hydrotalcite by impregnation with K2CO3.

    Science.gov (United States)

    Lee, Jung Moo; Min, Yoon Jae; Lee, Ki Bong; Jeon, Sang Goo; Na, Jeong Geol; Ryu, Ho Jung

    2010-12-21

    The awareness of symptoms of global warming and its seriousness urges the development of technologies to reduce greenhouse gas emissions. Carbon dioxide (CO(2)) is a representative greenhouse gas, and numerous methods to capture and storage CO(2) have been considered. Recently, the technology to remove high-temperature CO(2) by sorption has received lots of attention. In this study, hydrotalcite, which has been known to have CO(2) sorption capability at high temperature, was impregnated with K(2)CO(3) to enhance CO(2) sorption uptake, and the mechanism of CO(2) sorption enhancement on K(2)CO(3)-promoted hydrotalcite was investigated. Thermogravimetric analysis was used to measure equilibrium CO(2) sorption uptake and to estimate CO(2) sorption kinetics. The analyses based on N(2) gas physisorption, X-ray diffractometry, Fourier transform infrared spectrometry, Raman spectrometry, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to elucidate the characteristics of sorbents and the mechanism of enhanced CO(2) sorption. The equilibrium CO(2) sorption uptake on hydrotalcite could be increased up to 10 times by impregnation with K(2)CO(3), and there was an optimal amount of K(2)CO(3) for a maximum equilibrium CO(2) sorption uptake. In the K(2)CO(3)-promoted hydrotalcite, K(2)CO(3) was incorporated without changing the structure of hydrotalcite and it was thermally stabilized, resulting in the enhanced equilibrium CO(2) sorption uptake and fast CO(2) sorption kinetics.

  18. AMBIENT CARBONATION of MINING RESIDUES: Understanding the Mechanisms and Optimization of Direct Carbon Dioxide Mineral Sequestration

    Science.gov (United States)

    Assima, G. P.; Larachi, F.; Molson, J. W.; Beaudoin, G.

    2013-12-01

    The huge amounts (GTs) of ultramafic mining residues (UMRs) produced by mining activities around the world and accumulated in multi-square-kilometer stockpiles are stimulating a vivid interest regarding their possible use as a stable and permanent sink for CO2. Virtually costless and often found crushed and / or ground, UMRs are being considered as ideal candidates for atmospheric CO2 mitigation. The present work, therefore, explores the potential of several UMRs available in Quebec (Thetford Mines, Asbestos, Nunavik, Amos, Otish Mountains), for carbonation under ambient conditions, as a cost-effective alternative to remove low-concentration CO2 from the atmosphere and alleviate global warming. Several experimental reactors have been built to specifically simulate various climatic changes at the laboratory scale. The impact of various environmental conditions to which the residues are subjected to in their storage location, including temperature variations, precipitation, flooding, drought, changing water saturation, oxygen gradient and CO2 diffusion have been thoroughly studied. Dry and heavy-rain periods are unsuitable for efficient CO2 sequestration. Low liquid saturation within UMRs pores favors carbonation by combining fast percolation of gaseous CO2, rapid dissemination of CO2 dissolved species and creation of highly reactive sites throughout the mining residue pile. Partly saturated samples were also found to exhibit lower gaseous CO2 breakthrough times across the mining residues. Warm periods significantly accelerate the rate of CO2 uptake as compared to cold periods, which, in contrast are characterized by heat generation levels that could possibly be exploited by low temperature geothermal systems. A temperature rise from 10 to 40 °C was accompanied by a ten-fold increase in initial reaction rate. The carbonation reaction caused a rise in UMRs temperature up to 4.9°C during experiments at a 10°C. The presence of oxygen in the reaction medium induces

  19. 多金属富集植物李氏禾根系对铜吸收机理的研究%Mechanisms of Cu Uptake in a Multi-metal Accumulating Plant Leersia hexandra Swartz

    Institute of Scientific and Technical Information of China (English)

    田静; 张学洪; 陈俊; 刘杰

    2014-01-01

    李氏禾(Leersia hexandra Swartz)是一种多金属富集植物,通过研究其根系吸收铜的途径和方式,有助于解释李氏禾对铜的富集现象,为开发李氏禾修复铜污染土壤的植物修复技术提供科学依据。本文在温室水培条件下,利用钙离子通道抑制剂(LaCl3)和钾离子通道抑制剂(TEA),研究了李氏禾根系铜吸收与钙、钾离子通道的关系;同时,在研究 ATP 酶抑制剂、解偶联剂和低温作用对铜吸收影响的基础上,探讨了李氏禾根系铜吸收与能量代谢的关系。结果表明,在1 mmol·L-1钙离子通道抑制剂的作用下,李氏禾根对铜的吸收明显被抑制了(p<0.05)。处理48 h后,李氏禾根中铜的浓度较对照下降了39.2%。这说明李氏禾根吸收铜与钙离子通道密切相关。在5 mmol·L-1钾离子通道抑制剂的作用下,李氏禾根对铜的吸收与对照没用显著差异。这表明,李氏禾根系对铜的吸收可能不是通过钾离子通道进行的。ATP酶抑制剂钒酸钠(Na3VO4)显著地抑制李氏禾根对铜的吸收(p<0.05)。25μmol·L-1和50μmol·L-1 Na3VO4处理48 h后,李氏禾根中铜的浓度较对照分别下降了26.2%和31.0%。由此,推测李氏禾根系对铜的吸收是一个消耗能量的过程。该结果与解偶联剂抑制实验结果相一致。在25μmol·L-1和50μmol·L-1解偶联剂2,4-二硝基苯酚(DNP)作用下,李氏禾根系中的铜浓度较对照分别下降了25.8%和42.7%。低温处理对李氏禾根吸收铜的抑制作用较解偶联剂和ATP酶抑制剂更为明显。2℃下暴露48 h,李氏禾根中铜的浓度较对照(25℃)下降了60.1%。这进一步证明了,李氏禾根系对铜的吸收存在消耗能量的主动过程。%Leersia hexandra Swartz is a multi-metal accumulating plant. The study on the mechanisms of Cu uptake by roots of L. hexandra will help to understand how plants accumulate copper. Additionally

  20. Wheat protection against powdery mildew by arbuscular mycorrhizal fungi : mechanisms and optimization

    OpenAIRE

    Mustafa, Ghalia

    2015-01-01

    The use of arbuscular mycorrhizal fungi (AMF) could be an innovative alternative to chemicals against fungal plant diseases. Our work aimed at studying the possible protective effect of arbuscular mycorrhization in the bread wheat (Triticum aestivum L.) against Blumeria graminis f. sp. tritici (Bgt), a biotrophic fungi responsible of wheat powdery mildew, a disease affecting the aerial plant organs. Wheat mycorrhizal inoculation by Funneliformis mosseae (Fm), under controlled and optimized co...

  1. Characterization and Optimization of Mechanical Properties of ABS Parts Manufactured by the Fused Deposition Modelling Process

    Directory of Open Access Journals (Sweden)

    Godfrey C. Onwubolu

    2014-01-01

    Full Text Available While fused deposition modelling (FDM is one of the most used additive manufacturing (AM techniques today due to its ability to manufacture very complex geometries, the major research issues have been to balance ability to produce aesthetically appealing looking products with functionality. In this study, five important process parameters such as layer thickness, part orientation, raster angle, raster width, and air gap have been considered to study their effects on tensile strength of test specimen, using design of experiment (DOE. Using group method of data handling (GMDH, mathematical models relating the response with the process parameters have been developed. Using differential evolution (DE, optimal process parameters have been found to achieve good strength simultaneously for the response. The optimization of the mathematical model realized results in maximized tensile strength. Consequently, the additive manufacturing part produced is improved by optimizing the process parameters. The predicted models obtained show good correlation with the measured values and can be used to generalize prediction for process conditions outside the current study. Results obtained are very promising and hence the approach presented in this paper has practical applications for design and manufacture of parts using additive manufacturing technologies.

  2. Anisometry anterior cruciate ligament sport injury mechanism study: a finite element model with optimization method.

    Science.gov (United States)

    Na, Li; Wang, Wei; Ye, Bin; Wu, Song

    2014-06-01

    ACL damage is one the most frequent causes of knee injuries and thus has long been the focus of research in biomechanics and sports medicine. Due to the anisometric geometry and functional complexity of the ACL in the knee joint, it is usually difficult to experimentally study the biomechanics of ACLs. Anatomically ACL geometry was obtained from both MR images and anatomical observations. The optimal material parameters of the ACL were obtained by using an optimization-based material identification method that minimized the differences between experimental results from ACL specimens and FE simulations. The optimal FE model simulated biomechanical responses of the ACL during complex combined injury-causing knee movements, it predicted stress concentrations on the top and middle side of the posterolateral (PL) bundles. This model was further validated by a clinical case of ACL injury diagnosed by MRI and arthroscope, it demonstrated that the locations of rupture in the patient's knee corresponded to those where the stresses and moments were predicted to be concentrated. The result implies that varus rotation played a contributing but secondary role in injury under combined movements, the ACL elevation angle, is positive correlated with the tensional loading tolerance of the ACL.

  3. Mechanism and optimization of fuel injection parameters on combustion noise of DI diesel engine

    Institute of Scientific and Technical Information of China (English)

    张庆辉; 郝志勇; 郑旭; 杨文英; 毛杰

    2016-01-01

    Combustion noise takes large proportion in diesel engine noise and the studies of its influence factors play an important role in noise reduction. Engine noise and cylinder pressure measurement experiments were carried out. And the improved attenuation curves were obtained, by which the engine noise was predicted. The effect of fuel injection parameters in combustion noise was investigated during the combustion process. At last, the method combining single variable optimization and multivariate combination was introduced to online optimize the combustion noise. The results show that injection parameters can affect the cylinder pressure rise rate and heat release rate, and consequently affect the cylinder pressure load and pressure oscillation to influence the combustion noise. Among these parameters, main injection advance angle has the greatest influence on the combustion noise, while the pilot injection interval time takes the second place, and the pilot injection quantity is of minimal impact. After the optimal design of the combustion noise, the average sound pressure level of the engine is distinctly reduced by 1.0 dB(A) generally. Meanwhile, the power, emission and economy performances are ensured.

  4. Optimization of internal migration as a mechanism for solving the problems of monotowns in Sverdlovsk region

    Directory of Open Access Journals (Sweden)

    Evgeniya Vladimirovna Nekrasova

    2012-06-01

    Full Text Available The problems of single-industry towns and their solutions are reviewed in this paper. The analysis of internal mobility of the population of Russia on the basis of sociological research and Gallup International Research Institute of the family is made. The necessity of optimization of commuting between the territories of the municipal level to address the one-company towns is underlined. A mathematical model for the optimization of the problem of migration flows between the territories of the municipal level for commuting by road was developed. Testing was conducted on a model example of the six type-representative singleindustry towns of Sverdlovsk region (Revdinskiy district, VerkhnyayaPyshma, towns of Krasnoturinsk, Krasnouralsk, Serov and Sukhoi Log. Taking into account the current situation on the labor market and future labor requirements, a division of municipalities in the territory of employment and departure of migrants was performed under consideration. An optimal plan was constructed in areas of employment in company towns of Sverdlovsk region, which is designed to implement the scheme of traffic from the north to the south of Sverdlovsk region with the organization of interchange hub in the city of Yekaterinburg.

  5. The pendular mechanism does not determine the optimal speed of loaded walking on gradients.

    Science.gov (United States)

    Gomeñuka, Natalia Andrea; Bona, Renata Luisa; da Rosa, Rodrigo Gomes; Peyré-Tartaruga, Leonardo Alexandre

    2016-06-01

    The pendular mechanism does not act as a primary mechanism in uphill walking due to the monotonic behavior of the mechanical energies of the center of mass. Nevertheless, recent evidence shows that there is an important minimization of energy expenditure by the pendular mechanism during walking on uphill gradients. In this study, we analyzed the optimum speed (OPT) of loaded human walking and the pendulum-like determining variables (Recovery R, Instantaneous pendular re-conversion Rint, and Congruity percentage %Cong). Ten young men walked on a treadmill at five different speeds and at three different treadmill incline gradients (0, +7 and +15%), with and without a load carried in their backpacks. We used indirect calorimetry and 3D motion analysis, and all of the data were analyzed by computational algorithms. Rint increased at higher speeds and decreased with increasing gradient. R and %Cong decreased with increasing gradient and increased with speed, independent of load. Thus, energy conversion by the pendular mechanism during walking on a 15% gradient is supported, and although this mechanism can explain the maintenance of OPT at low walking speeds, the pendular mechanism does not fully explain the energy minimization at higher speeds.

  6. Optimal Ordering Policy and Coordination Mechanism of a Supply Chain with Controllable Lead-Time-Dependent Demand Forecast

    Directory of Open Access Journals (Sweden)

    Hua-Ming Song

    2011-01-01

    Full Text Available This paper investigates the ordering decisions and coordination mechanism for a distributed short-life-cycle supply chain. The objective is to maximize the whole supply chain's expected profit and meanwhile make the supply chain participants achieve a Pareto improvement. We treat lead time as a controllable variable, thus the demand forecast is dependent on lead time: the shorter lead time, the better forecast. Moreover, optimal decision-making models for lead time and order quantity are formulated and compared in the decentralized and centralized cases. Besides, a three-parameter contract is proposed to coordinate the supply chain and alleviate the double margin in the decentralized scenario. In addition, based on the analysis of the models, we develop an algorithmic procedure to find the optimal ordering decisions. Finally, a numerical example is also presented to illustrate the results.

  7. Generic Mechanism of Optimal Energy Transfer Efficiency: A Scaling Theory of the Mean First Passage Time in Exciton Systems

    CERN Document Server

    Wu, Jianlan; Silbey, Robert J

    2013-01-01

    An asymptotic scaling theory is presented using the conceptual basis of trapping-free subspace (i.e., orthogonal subspace) to establish the generic mechanism of optimal efficiency of excitation energy transfer (EET) in light-harvesting systems. Analogous to Kramers' turnover in classical rate theory, the enhanced efficiency in the weak damping limit and the suppressed efficiency in the strong damping limit define two asymptotic scaling regimes, which are interpolated to predict the functional form of optimal efficiency of the trapping-free subspace. In the presence of static disorder, the scaling law of transfer time with respect to dephasing rate changes from linear to square root, suggesting a weaker dependence on the environment. Though formulated in the context of EET, the analysis and conclusions apply in general to open quantum processes, including electron transfer, fluorescence emission, and heat conduction.

  8. Optimized FPGA Implementation of the Thyroid Hormone Secretion Mechanism Using CAD Tools.

    Science.gov (United States)

    Alghazo, Jaafar M

    2017-02-01

    The goal of this paper is to implement the secretion mechanism of the Thyroid Hormone (TH) based on bio-mathematical differential eqs. (DE) on an FPGA chip. Hardware Descriptive Language (HDL) is used to develop a behavioral model of the mechanism derived from the DE. The Thyroid Hormone secretion mechanism is simulated with the interaction of the related stimulating and inhibiting hormones. Synthesis of the simulation is done with the aid of CAD tools and downloaded on a Field Programmable Gate Arrays (FPGAs) Chip. The chip output shows identical behavior to that of the designed algorithm through simulation. It is concluded that the chip mimics the Thyroid Hormone secretion mechanism. The chip, operating in real-time, is computer-independent stand-alone system.

  9. Cationic lipid-nanoceria hybrids, a novel nonviral vector-mediated gene delivery into mammalian cells: investigation of the cellular uptake mechanism.

    Science.gov (United States)

    Das, Joydeep; Han, Jae Woong; Choi, Yun-Jung; Song, Hyuk; Cho, Ssang-Goo; Park, Chankyu; Seo, Han Geuk; Kim, Jin-Hoi

    2016-07-06

    Gene therapy is a promising technique for the treatment of various diseases. The development of minimally toxic and highly efficient non-viral gene delivery vectors is the most challenging undertaking in the field of gene therapy. Here, we developed dimethyldioctadecylammonium bromide (DODAB)-nanoceria (CeO2) hybrids as a new class of non-viral gene delivery vectors. These DODAB-modified CeO2 nanoparticles (CeO2/DODAB) could effectively compact the pDNA, allowing for highly efficient gene transfection into the selected cell lines. The CeO2/DODAB nanovectors were also found to be non-toxic and did not induce ROS formation as well as any stress responsive and pro-survival signaling pathways. The overall vector performance of CeO2/DODAB nanohybrids was comparable with lipofectamine and DOTAP, and higher than calcium phosphate and DEAE-dextran for transfecting small plasmids. The increased cellular uptake of the nanovector/DNA complexes through clathrin- and caveolae-mediated endocytosis and subsequent release from the endosomes further support the increased gene transfection efficiency of the CeO2/DODAB vectors. Besides, CeO2/DODAB nanovectors could transfect genes in vivo without any sign of toxicity. Taken together, this new nano-vector has the potential to be used for gene delivery in biomedical applications.

  10. Cyclophilin A enhances macrophage differentiation and lipid uptake in high glucose conditions: a cellular mechanism for accelerated macro vascular disease in diabetes mellitus.

    Science.gov (United States)

    Ramachandran, Surya; Vinitha, Anandan; Kartha, Cheranellore Chandrasekharan

    2016-11-03

    Vascular disease in diabetes is initiated by monocyte adhesion to vascular endothelium, transmigration and formation of foam cells. Increasing clinical evidence supports a role for the secretory protein, cyclophilin A in diabetic vascular disease. The means by which cyclophilin A contributes to vascular lesion development in diabetes is however largely unknown. In this study we investigated using THP1 cells and human monocytes whether cyclophilin A under hyperglycemic conditions, functions in the inflammatory cascade as a chemoattractant and increases lipid uptake by formation of foam cells invitro. We developed an invitro model of monocytes cultured in 20 mm glucose (high glucose) equivalent to 360 mg/dL of plasma glucose levels. These monocytes were then differentiated into macrophages using PMA and subsequently transformed to lipid laden foam cells using oxidized low density lipoproteins in the presence and absence of cyclophilin A. This cellular model was used to study monocyte to macrophage differentiation, transmigration and foam cell formation. A similar cellular model using siRNA mediated transient elimination of the cyclophilin A gene as well as chemical inhibitors were used to further confirm the role of cyclophilin A in the differentiation and foam cell formation process. Cyclophilin A effectively increased migration of high glucose treated monocytes to the endothelial cell monolayer (p diabetes mellitus.

  11. Methyl 6-Amino-6-deoxy-d-pyranoside-Conjugated Platinum(II) Complexes for Glucose Transporter (GLUT)-Mediated Tumor Targeting: Synthesis, Cytotoxicity, and Cellular Uptake Mechanism.

    Science.gov (United States)

    Li, Taoli; Gao, Xiangqian; Yang, Liu; Shi, Yunli; Gao, Qingzhi

    2016-05-19

    Methyl 6-aminodeoxy-d-pyranoside-derived platinum(II) glycoconjugates were designed and synthesized based on the clinical drug oxaliplatin for glucose transporter (GLUT)-mediated tumor targeting. In addition to a substantial improvement in water solubility, the conjugates exhibited cytotoxicity similar to or higher than that of oxaliplatin in six different human cancer cell lines. GLUT-mediated transport of the complexes was investigated with a cell-based fluorescence competition assay and GLUT-inhibitor-mediated cytotoxicity analysis in a GLUT-overexpressing human colorectal adenocarcinoma (HT29) cell line. The antitumor effect of the aminodeoxypyranoside-conjugated platinum(II) complexes was found to depend significantly on the GLUT inhibitor, and the cellular uptake of the molecules was regulated by GLUT-mediated transport. The results from this study demonstrate the potential advantages of aminodeoxypyranosides as sugar motifs for glycoconjugation for Warburg-effect-targeted drug design. These fundamental results also support the potential of aminodeoxypyranoside-conjugated platinum(II) complexes as lead compounds for further preclinical evaluation.

  12. Silicon occurrence, uptake, transport and mechanisms of heavy metals, minerals and salinity enhanced tolerance in plants with future prospects: A review.

    Science.gov (United States)

    Imtiaz, Muhammad; Rizwan, Muhammad Shahid; Mushtaq, Muhammad Adnan; Ashraf, Muhammad; Shahzad, Sher Muhammad; Yousaf, Balal; Saeed, Dawood Anser; Rizwan, Muhammad; Nawaz, Muhammad Azher; Mehmood, Sajid; Tu, Shuxin

    2016-12-01

    Recently, heavy metals pollution due to industrialization and urbanization, use of untreated wastewater and unreasonable use of pesticides and fertilizers is increasing rapidly, resulting in major threat to the environment and contaminate soils. Silicon (Si) is the second most abundant element in the earth crust after oxygen. Although it's higher accumulation in plants, yet Si has not been listed as essential nutrient however, considered as beneficial element for growth of plants particularly in stressed environment. Research to date has demonstrated that silicon helps the plants to alleviate the various biotic and abiotic stresses. This review article presents a comprehensive update about Si and heavy metals, minerals and salinity stresses, and contained the progress about Si so far done worldwide in the light of previous studies to evaluate the ecological importance of Si. Moreover, this review will also be helpful to understand the Si uptake ability and its benefits on plants grown under stressed environment. Further research needs for Si-mediated mitigation of heavy metals and mineral nutrients stresses are also discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Structural and mechanical evaluations of a topology optimized titanium interbody fusion cage fabricated by selective laser melting process.

    Science.gov (United States)

    Lin, Chia-Ying; Wirtz, Tobias; LaMarca, Frank; Hollister, Scott J

    2007-11-01

    A topology optimized lumbar interbody fusion cage was made of Ti-Al6-V4 alloy by the rapid prototyping process of selective laser melting (SLM) to reproduce designed microstructure features. Radiographic characterizations and the mechanical properties were investigated to determine how the structural characteristics of the fabricated cage were reproduced from design characteristics using micro-computed tomography scanning. The mechanical modulus of the designed cage was also measured to compare with tantalum, a widely used porous metal. The designed microstructures can be clearly seen in the micrographs of the micro-CT and scanning electron microscopy examinations, showing the SLM process can reproduce intricate microscopic features from the original designs. No imaging artifacts from micro-CT were found. The average compressive modulus of the tested caged was 2.97+/-0.90 GPa, which is comparable with the reported porous tantalum modulus of 3 GPa and falls between that of cortical bone (15 GPa) and trabecular bone (0.1-0.5 GPa). The new porous Ti-6Al-4V optimal-structure cage fabricated by SLM process gave consistent mechanical properties without artifactual distortion in the imaging modalities and thus it can be a promising alternative as a porous implant for spine fusion.

  14. Optimal elastic coupling in form of one mechanical spring to improve energy efficiency of walking bipedal robots

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Fabian; Römer, Ulrich, E-mail: ulrich.roemer@kit.edu; Fidlin, Alexander; Seemann, Wolfgang [Institute of Engineering Mechanics, Karlsruhe Institute of Technology (Germany)

    2016-11-15

    This paper presents a method to optimize the energy efficiency of walking bipedal robots by more than 80 % in a speed range from 0.3 to 2.3 m/s using elastic couplings—mechanical springs with movement speed independent parameters. The considered planar robot consists of a trunk, two two-segmented legs, two actuators in the hip joints, two actuators in the knee joints and an elastic coupling between the shanks. It is modeled as underactuated system to make use of its natural dynamics and feedback controlled via input–output linearization. A numerical optimization of the joint angle trajectories as well as the elastic couplings is performed to minimize the average energy expenditure over the whole speed range. The elastic couplings increase the swing leg motion’s natural frequency thus making smaller steps more efficient which reduce the impact loss at the touchdown of the swing leg. The process of energy turnover is investigated in detail for the robot with and without elastic coupling between the shanks. Furthermore, the influences of the elastic couplings’ topology and of joint friction are analyzed. It is shown that the optimization of the robot’s motion and elastic coupling towards energy efficiency leads to a slightly slower convergence rate of the controller, yet no loss of stability, but a lower sensitivity with respect to disturbances. The optimal elastic coupling discovered via numerical optimization is a linear torsion spring with transmissions between the shanks. A design proposal for this elastic coupling—which does not affect the robot’s trunk and parallel shank motion and can be used to enhance an existing robot—is given for planar as well as spatial robots.

  15. Pulmonary uptake of morphine (M)

    Energy Technology Data Exchange (ETDEWEB)

    Roerig, D.L.; Bunke, S.S.; Kotrly, K.J.; Dawson, C.A.; Kampine, J.P.

    1986-03-01

    Previously the authors reported less than 5% of M was taken up during the first pass through the human lung. The low uptake of this basic lipophilic amine was further investigated in a single pass isolated perfused rat lung (IPL) in comparison to uptake of radiolabelled H/sub 2/O, antipyrine (A), aminopyrine (AM), nicotine (N) and phenylethylamine (P). The IPL was perfused for 5 min with each drug (5nmol/ml) and effluent collected in 10 sec fractions. Pulmonary extraction was calculated using indocyanine green dye as a non-extractable reference indicator. Accumulation of all compounds in the IPL reached an apparent equilibrium within 4 min. At equilibrium lung/perfusate conc. ratios for H/sub 2/O, A, AM, N, P and M were 1.04, 0.84, 0.85, 1.44, 2.57 and 1.13 respectively. The time course of M uptake differed from the other compounds since initial extraction of M was low (23%) compared to 75%, 53%, 35%, 82% and 86% for H/sub 2/O, A, AM, N and P respectively. Also, the half time to equilibrium for M was longer (50 sec) compared to 18, 21, 26, 19 and 22 sec for H/sub 2/O, A, AM, N and P respectively. The low initial pulmonary extraction of M compared to these compounds followed by greater M extraction during the remainder of drug infusion suggests uptake mechanisms for M different than the flow limited uptake for water and other basic amine drugs.

  16. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  17. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) is also known as a thyroid uptake. ...

  18. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  19. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) is also known as a thyroid uptake. ...

  20. Optimization of mechanical and damping properties of Mg–0.6Zr alloy by different extrusion processing

    OpenAIRE

    Wang, Jingfeng; Wu, Zhongshan; Gao, Shan; Lu, Ruopeng; Qin, Dezhao; Yang,Wenxiang; Pan, Fusheng

    2015-01-01

    In this study, the optimization of mechanical and damping capacities of Mg-0.6 wt.% Zr alloys by controlling the recrystallized (DRXed) grain size under varying extrusion processing parameters including extrusion temperature T and strain rate ε˙ was investigated. The relationship between the DRXed grain size and damping properties of the studied alloy was also discussed. The DRXed grain size of the as-extruded Mg–Zr alloys decreased as the extrusion temperature T decreased and the strain rate...

  1. Research on and Design of Mechanical System with Optimal Cutting Movement Trajectory of Energy-Saving Stone-Sawing Machine

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The technique of cutting slabstone with stone-sawi ng machine is analyzed completely. A new kind of cutting movement trajectory is gi ven whose actual cutting efficiency is near to 100%. It can reduce the energy w earing greatly, and the surface quality of the product is improved to the utmost extent. The design mechanism of the optimal cutting movement trajectory system structure is analyzed incisively. At the same time, the principle of the complex movement of horizontal movement and swing is resear...

  2. Topology Optimization of Nano-Mechanical Cantilever Sensors Using a C0 Discontinuous Galerkin-Type Approach

    DEFF Research Database (Denmark)

    Marhadi, Kun Saptohartyadi; Evgrafov, Anton; Sørensen, Mads Peter

    2011-01-01

    We demonstrate the use of a C0 discontinuous Galerkin method for topology optimization of nano-mechanical sensors, namely temperature, surface stress, and mass sensors. The sensors are modeled using classical thin plate theory, which requires C1 basis functions in the standard finite element method....... A discontinuous Galerkin type approach allows the use of C0 basis functions or any common basis functions, e.g. based on Lagrange elements. Thus the implementation is simple and requires fewer degrees of freedom per element compared to common finite element implementation of plate problems....

  3. Elucidating double aggregation mechanisms in the morphology optimization of diketopyrrolopyrrole-based narrow bandgap polymer solar cells.

    Science.gov (United States)

    Gao, Jing; Chen, Wei; Dou, Letian; Chen, Chun-Chao; Chang, Wei-Hsuan; Liu, Yongsheng; Li, Gang; Yang, Yang

    2014-05-21

    The power conversion efficiency (PCE) of a DPP-based polymer solar cell is significantly improved by using DIO or DCB as processing additives. The discovery that DCB outperforms DIO with a significantly wider solvent mixture operation window suggests different optimization mechanisms. Although both solvent mixture systems involve double aggregation processes, including a similar solution-to-film aggregation, however, two distinct solution-stage aggregations are observed: relatively amorphous polymer aggregates form in the CF-DIO solution, while more crystalline polymer aggregates form in CF-DCB solution.

  4. 汽车转向机构建模及优化%Modeling and Optimization of Automobile Steering Mechanism

    Institute of Scientific and Technical Information of China (English)

    吴忠岚; 邓传奇; 陈帅; 李学明; 唐琼; 周毅钧

    2016-01-01

    运用ADAMS动力学分析软件建立了汽车转向机构的参数化模型。在对汽车转向机构中的转向梯形进行仿真分析的同时,简单分析了悬架系统对汽车转向的影响。考虑到转向梯形机构的转向臂以及梯形底角对汽车内外转向角的影响是最大的,利用ADAMS自带优化程序创建设计变量对梯形机构的关键点进行优化计算,优化过程中将悬架机构和转向梯形机构作为不同机构,仅对转向机构进行迭代优化,得到转向臂和梯形底角的最优参数。通过对比优化前后的内外转向角随时间变化的规律,可以明显观察到,优化后的转向角之差是小于优化前的,转向特性曲线更加接近理想值,提高了汽车的安全性,增加了轮胎寿命。%In this paper, the parametric model of automobile steering mechanism is established by applying the dynamic analy-sis software ADAMS; simulation analysis on the steering trapezium of automobile steering mechanism is conducted, at the same time, simple analysis on influences of the suspension system to the automobile steering is also conducted.Considering that the steering arm and trapezoid corner have a big impact on steering angle, the built-in optimization program of ADAMS is used to creat design variables ao as to optimize the calculation of critical points of the trapezoid body; in the optimization process, the suspension mechanism and the steering trapezium are set as the different agencies, and the iterative optimization is only conducted to the steering mechanism, thus the optimal parameters of steering arm and trapezoid corner are obtained. Through comparing the law of the inner and outer steering angle changing with time before and after optimization, it could be clearly observed that the steering angle after optimization is less than before, and the steering characteristic value is closer to the ideal curve, thus it could improve safety of the vehicle and increase

  5. OPTIMIZATION OF PROCESS PARAMETERS FOR ENHANCED MECHANICAL PROPERTIES OF POLYPROPYLENE TERNARY NANOCOMPOSITES

    Directory of Open Access Journals (Sweden)

    Oladipupo Olaosebikan Ogunleye

    2015-02-01

    Full Text Available Preparation of Polypropylene ternary nanocomposites (PPTN was accomplished by blending multiwall carbon nanotube (MWCNT in polypropylene/clay binary system using a melt intercalation method. The effects of MWCNT loadings (A, melting temperature (B and mixing speed (C were investigated and optimized using central composite design. The analysis of the fitted cubic model clearly indicated that A and B were the main factors influencing the tensile properties at a fixed value of C. However, the analysis of variance showed that the interactions between the process parameters, such as; AB, AC, AB2, A2B and ABC, were highly significant on both tensile strength and Young’s modulus enhancement, while no interaction is significant in all models considered for elongation. The established optimal conditions gave 0.17%, 165 °C, and 120 rpm for A, B and C, respectively. These conditions yielded a percentage increase of 57 and 63% for tensile strength and Young’s modulus respectively compared to the virgin Polypropylene used.

  6. Study on Different Crossover Mechanisms of Genetic Algorithm for Test Interval Optimization for Nuclear Power Plants

    Directory of Open Access Journals (Sweden)

    Molly Mehra

    2013-12-01

    Full Text Available Surveillance tests are performed periodically on standby systems of a Nuclear Power Plant (NPP, as they improve the systems’ availability on demand. High availability of safety critical systems is very essential to NPP safety, hence, careful analysis is required to schedule the surveillance activities for such systems in a cost effective way without compromising the plant safety. This forms an optimization problem wherein, two different cases can be formulated for deciding the value of Surveillance Test Interval. In one case, cost is the objective function to be minimized while unavailability is constrained to be at a given level and in another case, unavailability is minimized for a given cost level. Here, optimization is done using Genetic Algorithm (GA and real encoding has been employed as it caters well to the requirements of this problem. A detailed procedure for GA formulation is described in this paper. Two different crossover methods, arithmetical crossover and blend crossover are explored and compared in this study to arrive at the most suitable crossover method for such type of problems.

  7. Strengthening mechanisms and optimization of structure and properties in a nanostructured IF steel

    DEFF Research Database (Denmark)

    Huang, Xiaoxu; Kamikawa, N.; Hansen, Niels

    2010-01-01

    . Structural parameters including boundary spacing, misorientation angle, and dislocation density have been quantified by means of transmission electron microscopy and mechanical properties have been determined by tensile testing for the as-ARB processed samples and for the post-process treated samples...

  8. Hard and soft sub-time-optimal controllers for a mechanical system with uncertain mass

    DEFF Research Database (Denmark)

    Kulczycki, P.; Wisniewski, Rafal; Kowalski, P.

    2004-01-01

    by parameters selected in accordance with the rules of the statistical decision theory; however, the soft structure allows additionally to eliminate rapid changes in control values. The object is a basic mechanical system, with uncertain (also non-stationary) mass treated as a stochastic process...

  9. Hard and soft Sub-Time-Optimal Controllers for a Mechanical System with Uncertain Mass

    DEFF Research Database (Denmark)

    Kulczycki, P.; Wisniewski, Rafal; Kowalski, P.

    2005-01-01

    by parameters selected in accordance with the rules of the statistical decision theory; however, the soft structure allows additionally to eliminate rapid changes in control values. The object is a basic mechanical system, with uncertain (also non-stationary) mass treated as a stochastic process...

  10. A continuum mechanics-based framework for optimizing boundary and finite element meshes associated with underground excavations-framework

    Science.gov (United States)

    Zsáki, Attila M.; Curran, John H.

    2005-11-01

    Many field problems, from stress analysis, heat transfer to contaminant transport, deal with disturbances in a continuum caused by a source (defined by its discrete geometry) and a region of interest (where a solution is sought). Depending on the location of regions of interest in relation to the sources, the level of geometric detail necessary to represent the sources in a model can vary considerably. A practical application of stress analysis in mining is the evaluation of the effects of continuous excavation on the states of stress around mine openings. Labour intensive model preparation and lengthy computation coupled with the interpretation of analysis results can have considerable impact on the successful operation of an underground mine, where stope failures can cost tens of millions of dollars and possibly lead to closure of the mine.A framework is proposed based on continuum mechanics principles to automatically optimize the level of geometric detail required for an analysis by simplifying the model geometry using expanded and modified algorithms that originated in computer graphics. This reduction in model size directly translates to savings in computational time. The results obtained from an optimized model have accuracy comparable to the uncertainty in input data (e.g. rock mass properties, geology, etc.). This first paper defines the optimization framework, while a companion paper investigates its efficiency and application to practical mining and excavation-related problems. Copyright

  11. Design Optimization of Nuclear Vapor Thermal Rocket Core - A Thermo-Mechanical Study

    Science.gov (United States)

    Keshavmurthy, Shyam P.; Watanabe, Yoichi; Dugan, Edward T.; Diaz, Nils J.

    1994-07-01

    Fuel structural materials for the Nuclear Vapor Thermal Rocket (NVTR) are exposed to very high temperature vapor fuel in the fuel channel and to high temperature but cooler propellant in the coolant channel. This temperature difference leads to thermal stress in the fuel element. There is also a mismatch in the value of coefficients of thermal expansion between the fuel element material and the coating material that could lead to failure of the coating. The stress in the coating and the fuel element material is dependent on the power density of the core and also on the arrangement of fuel and coolant channels. In order to achieve higher power density, the fuel element design has to be optimized to yield lower stress. Analytical studies found that carbon/carbon composite hexagonal fuel elements employing a square lattice arrangement of multiple UF4 fuel and hydrogen coolant channels yield maximum stress intensities well below fuel element materials stress limit.

  12. Design, modeling and optimization of an underwater manipulator with four-bar mechanism and compliant linkage

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Sang Ok; Kim, Ji Hoon; Bae, Jang Ho; Kim, Jong Won [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Seo, Tae Won [School of Mechanical Engineering, Yeungnam University, Gyeongsan (Korea, Republic of)

    2016-09-15

    Underwater manipulators are very important for a robot to perform a specific operation in water. Conventional robot arm manipulators have been suggested for various operations but have not been suitable for repeated motion in gathering something. This paper presents a new underwater manipulator design for gathering things such as starfish on the sea floor. The manipulator is composed of a four-bar linkage to achieve repeated motion along a loop and compliant linkages to enhance the efficiency of the gathering work. Kinematic and quasi-static analyses were performed to calculate the loop path and the reaction force at the actuation point. Based on the analysis, optimal design was performed to maximize the working distance with the height difference and the reaction moments considered as constraints. A prototype was assembled to test the performance of the manipulator, and the empirical loop path was compared to simulation results.

  13. Effects of transport inhibitors on the cellular uptake of carboxylated polystyrene nanoparticles in different cell lines.

    Directory of Open Access Journals (Sweden)

    Tiago dos Santos

    Full Text Available Nanotechnology is expected to play a vital role in the rapidly developing field of nanomedicine, creating innovative solutions and therapies for currently untreatable diseases, and providing new tools for various biomedical applications, such as drug delivery and gene therapy. In order to optimize the efficacy of nanoparticle (NP delivery to cells, it is necessary to understand the mechanisms by which NPs are internalized by cells, as this will likely determine their ultimate sub-cellular fate and localisation. Here we have used pharmacological inhibitors of some of the major endocytic pathways to investigate nanoparticle uptake mechanisms in a range of representative human cell lines, including HeLa (cervical cancer, A549 (lung carcinoma and 1321N1 (brain astrocytoma. Chlorpromazine and genistein were used to inhibit clathrin and caveolin mediated endocytosis, respectively. Cytochalasin A and nocodazole were used to inhibit, respectively, the polymerisation of actin and microtubule cytoskeleton. Uptake experiments were performed systematically across the different cell lines, using carboxylated polystyrene NPs of 40 nm and 200 nm diameters, as model NPs of sizes comparable to typical endocytic cargoes. The results clearly indicated that, in all cases and cell types, NPs entered cells via active energy dependent processes. NP uptake in HeLa and 1321N1 cells was strongly affected by actin depolymerisation, while A549 cells showed a stronger inhibition of NP uptake (in comparison to the other cell types after microtubule disruption and treatment with genistein. A strong reduction of NP uptake was observed after chlorpromazine treatment only in the case of 1321N1 cells. These outcomes suggested that the same NP might exploit different uptake mechanisms to enter different cell types.

  14. Self-Assembly into Nanoparticles Is Essential for Receptor Mediated Uptake of Therapeutic Antisense Oligonucleotides.

    Science.gov (United States)

    Ezzat, Kariem; Aoki, Yoshitsugu; Koo, Taeyoung; McClorey, Graham; Benner, Leif; Coenen-Stass, Anna; O'Donovan, Liz; Lehto, Taavi; Garcia-Guerra, Antonio; Nordin, Joel; Saleh, Amer F; Behlke, Mark; Morris, John; Goyenvalle, Aurelie; Dugovic, Branislav; Leumann, Christian; Gordon, Siamon; Gait, Michael J; El-Andaloussi, Samir; Wood, Matthew J A

    2015-07-08

    Antisense oligonucleotides (ASOs) have the potential to revolutionize medicine due to their ability to manipulate gene function for therapeutic purposes. ASOs are chemically modified and/or incorporated within nanoparticles to enhance their stability and cellular uptake, however, a major challenge is the poor understanding of their uptake mechanisms, which would facilitate improved ASO designs with enhanced activity and reduced toxicity. Here, we study the uptake mechanism of three therapeutically relevant ASOs (peptide-conjugated phosphorodiamidate morpholino (PPMO), 2'Omethyl phosphorothioate (2'OMe), and phosphorothioated tricyclo DNA (tcDNA) that have been optimized to induce exon skipping in models of Duchenne muscular dystrophy (DMD). We show that PPMO and tcDNA have high propensity to spontaneously self-assemble into nanoparticles. PPMO forms micelles of defined size and their net charge (zeta potential) is dependent on the medium and concentration. In biomimetic conditions and at low concentrations, PPMO obtains net negative charge and its uptake is mediated by class A scavenger receptor subtypes (SCARAs) as shown by competitive inhibition and RNAi silencing experiments in vitro. In vivo, the activity of PPMO was significantly decreased in SCARA1 knockout mice compared to wild-type animals. Additionally, we show that SCARA1 is involved in the uptake of tcDNA and 2'OMe as shown by competitive inhibition and colocalization experiments. Surface plasmon resonance binding analysis to SCARA1 demonstrated that PPMO and tcDNA have higher binding profiles to the receptor compared to 2'OMe. These results demonstrate receptor-mediated uptake for a range of therapeutic ASO chemistries, a mechanism that is dependent on their self-assembly into nanoparticles.

  15. Progress of molecular and physiological mechanism of iron uptake and translocation in plants%植物吸收和转运铁的分子生理机制研究进展

    Institute of Scientific and Technical Information of China (English)

    申红芸; 熊宏春; 郭笑彤; 左元梅

    2011-01-01

    Fe is essential for plant growth.However,plants show severe iron deficiency due to low availability of Fe in soils,which affects the yield and quality of crops and ultimately affects human nutrition.Therefore,it is the hot research area to improve human nutritional status through biofortification.This review covers the research progress on the molecular mechanism of Fe uptake and translocation in plants and deposition in seeds in the past five years,and includes new discovery of combination of reduction and chelation strategies of iron uptake in Rice and the importance of YSL family in the three biological processes in plants.Furthermore,the technical ways of iron nutrition improvement and iron enrichment in seeds by genetic engineering and agronomic measures based on the studies on molecular mechanism of iron uptake and translocation in plants are discussed.%铁是植物正常生命活动过程中的必需微量元素之一。由于土壤中铁的有效性很低,导致植物极易缺铁,不仅影响作物的产量和品质,而且影响人类微量元素健康,因此如何通过生物强化达到人类铁营养状况改善的目的是目前该研究领域关注的热点。本文就近5年来植物铁吸收、体内转运、子粒中积累等重要生物过程的分子生理机制的研究进展进行了详细阐述,其中对水稻兼备机理Ⅰ和机理Ⅱ铁吸收机制有了新的认识,而且发现YSL蛋白家族在植物铁吸收、转运和子粒积累过程中的重要性。同时,讨论了利用上述机制的研究结果通过基因工程和农学措施改善植物铁营养和提高作物子粒铁富集的技术途径。

  16. Clarithromycin is absorbed by an intestinal uptake mechanism that is sensitive to major inhibition by rifampicin: results of a short-term drug interaction study in foals.

    Science.gov (United States)

    Peters, Jette; Eggers, Karen; Oswald, Stefan; Block, Wiebke; Lütjohann, Dieter; Lämmer, Marc; Venner, Monica; Siegmund, Werner

    2012-03-01

    Pulmonary penetration of clarithromycin (CLR) in epithelial lining fluid (ELF) and bronchoalveolar lavage cells (BALCs) can be influenced by CYP3A4, by P-glycoprotein, and, according to our hypothesis, by a member of the organic anion-transporting protein (OATP) family, for which rifampicin (RIF) is inhibiting in single doses but inducing after long-term coadministration. To assess the partial inhibitory effect, we measured absorption and pulmonary distribution of CLR after short-term (2.5-day) coadministration of RIF, after which up-regulation is not expected. The drug interaction study was performed with five doses (12-h interval) of CLR (7.5 mg/kg) and RIF (10 mg/kg) in nine healthy foals; horse transporters are very similar in protein sequence and transcriptional regulation to the human analogs. RIF was equally distributed in ELF but reached half the plasma levels in BALCs. The deacetylated metabolite accumulated 1.4- to 6-fold in ELF and 8- to 60-fold in BALCs. CLR did not significantly influence the distribution of RIF. CLR and 14-hydroxyclarithromycin (14OH-CLR) accumulated approximately 20- to 40-fold and 1.5- to 4.5-fold in ELF and 300- to 1800-fold and 25- to 90-fold in BALCs, respectively. With RIF, plasma levels of CLR decreased by more than 70% without changes in 14OH-CLR formation, the half-lives of CLR and 14OH-CLR, and the 4β-hydroxycholesterol/cholesterol ratio (a surrogate for CYP3A4 induction). CLR was an inhibitor of OATP1B3 (IC(50) = 9.50 ± 3.50 μM), OATP1B1 (IC(50) = 46.0 ± 2.27 μM), OATP1A2 (IC(50) = 92.6 ± 1.49 μM), and OATP2B1 (IC(50) = 384 ± 5.30 μM) but was not a substrate for these transporters in transfected human embryonic kidney cells. In conclusion, despite having no significant inducing effects, RIF decreased plasma levels of CLR below the minimal inhibitory concentration required to inhibit 90% of growth of pathogenic bacteria, most likely through inhibition of an unknown intestinal uptake transporter.

  17. Optimization of FS Welding Parameters for Improving Mechanical Behavior of AA2024-T351 Joints Based on Taguchi Method

    Science.gov (United States)

    Vidal, C.; Infante, V.

    2013-08-01

    In the present study, the design of an experiment technique, the Taguchi method, has been used to optimize the friction stir welding (FSW) parameters for improving mechanical behavior of AA2024-T351 joints. The parameters considered were vertical downward forging force, tool travel speed, and probe length. An orthogonal array of L9 (34) was used; ANOVA analyses were carried out to identify the significant factors affecting tensile strength (Global Efficiency to Tensile Strength—GETS), bending strength (Global Efficiency to Bending—GEB), and hardness field. The percentage contribution of each parameter was also determined. As a result of the Taguchi analysis in this study, the probe length is the most significant parameter on GETS, and the tool travel speed is the most important parameter affecting both the GEB and the hardness field. An algebraic model for predicting the best mechanical performance, namely fatigue resistance, was developed and the optimal FSW combination was determined using this model. The results obtained were validated by conducting confirmation tests, the results of which verify the adequacy and effectiveness of this approach.

  18. Unraveling the Fundamental Mechanisms of Solvent-Additive-Induced Optimization of Power Conversion Efficiencies in Organic Photovoltaic Devices.

    Science.gov (United States)

    Herath, Nuradhika; Das, Sanjib; Zhu, Jiahua; Kumar, Rajeev; Chen, Jihua; Xiao, Kai; Gu, Gong; Browning, James F; Sumpter, Bobby G; Ivanov, Ilia N; Lauter, Valeria

    2016-08-10

    The realization of controllable morphologies of bulk heterojunctions (BHJ) in organic photovoltaics (OPVs) is one of the key factors enabling high-efficiency devices. We provide new insights into the fundamental mechanisms essential for the optimization of power conversion efficiencies (PCEs) with additive processing to PBDTTT-CF:PC71BM system. We have studied the underlying mechanisms by monitoring the 3D nanostructural modifications in BHJs and correlated the modifications with the optical analysis and theoretical modeling of charge transport. Our results demonstrate profound effects of diiodooctane (DIO) on morphology and charge transport in the active layers. For small amounts of DIO (3 vol %), DIO facilitates a loosely packed mixed morphology with large clusters of PC71BM, leading to deterioration in PCE. Theoretical modeling of charge transport reveals that DIO increases the mobility of electrons and holes (the charge carriers) by affecting the energetic disorder and electric field dependence of the mobility. Our findings show the implications of phase separation and carrier transport pathways to achieve optimal device performances.

  19. Optimization and Verification of a Brushless DC-Motor for Cryogenic Mechanisms

    Science.gov (United States)

    Eggens, M.; van Loon, D.; Smit, H. P.; Jellema, W.; Dieleman, P.; Detrain, A.; Stokroos, M.; Nieuwenhuizen, A. C. T.

    2013-09-01

    In this paper we report on the results of the investigation on the feasibility of a cryogenic motor for a Filter Wheel Mechanism (FWM) for the instrument SpicA FAR-infrared Instrument (SAFARI). The maximum allowed dissipation of 1 mW is a key requirement, as a result of the limited cooling resources of the satellite. Therefore a quasi 3D electromagnetic (EM) model of a Brushless DC (BLDC) motor has been developed. To withstand the severe launch loads a mechanical concept has been designed to limit the friction torque in the bearings. The model was verified by room temperature and cryogenic measurements on an existing motor from the test setup. The model shows that the proposed BLDC motor design fulfills the requirements.

  20. Single-Nanowire Electrochemical Probe Detection for Internally Optimized Mechanism of Porous Graphene in Electrochemical Devices.

    Science.gov (United States)

    Hu, Ping; Yan, Mengyu; Wang, Xuanpeng; Han, Chunhua; He, Liang; Wei, Xiujuan; Niu, Chaojiang; Zhao, Kangning; Tian, Xiaocong; Wei, Qiulong; Li, Zijia; Mai, Liqiang

    2016-03-09

    Graphene has been widely used to enhance the performance of energy storage devices due to its high conductivity, large surface area, and excellent mechanical flexibility. However, it is still unclear how graphene influences the electrochemical performance and reaction mechanisms of electrode materials. The single-nanowire electrochemical probe is an effective tool to explore the intrinsic mechanisms of the electrochemical reactions in situ. Here, pure MnO2 nanowires, reduced graphene oxide/MnO2 wire-in-scroll nanowires, and porous graphene oxide/MnO2 wire-in-scroll nanowires are employed to investigate the capacitance, ion diffusion coefficient, and charge storage mechanisms in single-nanowire electrochemical devices. The porous graphene oxide/MnO2 wire-in-scroll nanowire delivers an areal capacitance of 104 nF/μm(2), which is 4.0 and 2.8 times as high as those of reduced graphene oxide/MnO2 wire-in-scroll nanowire and MnO2 nanowire, respectively, at a scan rate of 20 mV/s. It is demonstrated that the reduced graphene oxide wrapping around the MnO2 nanowire greatly increases the electronic conductivity of the active materials, but decreases the ion diffusion coefficient because of the shielding effect of graphene. By creating pores in the graphene, the ion diffusion coefficient is recovered without degradation of the electron transport rate, which significantly improves the capacitance. Such single-nanowire electrochemical probes, which can detect electrochemical processes and behavior in situ, can also be fabricated with other active materials for energy storage and other applications in related fields.

  1. [Osteocytes and the pathways of mechanical homeostasis optimization from the point of view of functional osteology].

    Science.gov (United States)

    Avrunin, A S; Tikhilov, R M; Parshin, L K; Mel'nikov, B E

    2012-01-01

    The aim of this work was to determine, on the basis of the results of authors' own research and literature data, the main pathways of osteocyte (OC) influence on the mechanical homeostasis of the skeleton. The following pathways of reorganization of the architecture of bone structures are postulated: at the ultrastructural level without direct cell participation, through the bone matrix synthesis by osteoblasts and OC, through bone matrix resorption by osteoclasts and OC, the latter being able to resorb the surrounding mineral and organic matrix both separately, and conjointly. This reorganization results in local changes of the mechanical characteristics of bones due to changes in: porosity of interstitial spaces, transport ability of the lacunar-canalicular system, porosity of the area of osteoblastic-osteoclastic remodeling, modeling of bone structures. From the point of view of adaptation theory it is highly significant that the subtle local control of bone structures is able to induce changes in the parameters of the mechanical environment, which, on the one hand, would correspond to OC metabolic requirements and, on the other hand, would support the parameters of body mineral homeostasis.

  2. Quantum-Mechanics Methodologies in Drug Discovery: Applications of Docking and Scoring in Lead Optimization.

    Science.gov (United States)

    Crespo, Alejandro; Rodriguez-Granillo, Agustina; Lim, Victoria T

    2017-01-01

    The development and application of quantum mechanics (QM) methodologies in computer- aided drug design have flourished in the last 10 years. Despite the natural advantage of QM methods to predict binding affinities with a higher level of theory than those methods based on molecular mechanics (MM), there are only a few examples where diverse sets of protein-ligand targets have been evaluated simultaneously. In this work, we review recent advances in QM docking and scoring for those cases in which a systematic analysis has been performed. In addition, we introduce and validate a simplified QM/MM expression to compute protein-ligand binding energies. Overall, QMbased scoring functions are generally better to predict ligand affinities than those based on classical mechanics. However, the agreement between experimental activities and calculated binding energies is highly dependent on the specific chemical series considered. The advantage of more accurate QM methods is evident in cases where charge transfer and polarization effects are important, for example when metals are involved in the binding process or when dispersion forces play a significant role as in the case of hydrophobic or stacking interactions. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. A qrr noncoding RNA deploys four different regulatory mechanisms to optimize quorum-sensing dynamics.

    Science.gov (United States)

    Feng, Lihui; Rutherford, Steven T; Papenfort, Kai; Bagert, John D; van Kessel, Julia C; Tirrell, David A; Wingreen, Ned S; Bassler, Bonnie L

    2015-01-15

    Quorum sensing is a cell-cell communication process that bacteria use to transition between individual and social lifestyles. In vibrios, homologous small RNAs called the Qrr sRNAs function at the center of quorum-sensing pathways. The Qrr sRNAs regulate multiple mRNA targets including those encoding the quorum-sensing regulatory components luxR, luxO, luxM, and aphA. We show that a representative Qrr, Qrr3, uses four distinct mechanisms to control its particular targets: the Qrr3 sRNA represses luxR through catalytic degradation, represses luxM through coupled degradation, represses luxO through sequestration, and activates aphA by revealing the ribosome binding site while the sRNA itself is degraded. Qrr3 forms different base-pairing interactions with each mRNA target, and the particular pairing strategy determines which regulatory mechanism occurs. Combined mathematical modeling and experiments show that the specific Qrr regulatory mechanism employed governs the potency, dynamics, and competition of target mRNA regulation, which in turn, defines the overall quorum-sensing response.

  4. Mechanisms for efficient investments and optimal zones in regional power market

    Directory of Open Access Journals (Sweden)

    Andročec Ivan

    2014-01-01

    Full Text Available The paper is result of research different cross-border electricity trading mechanisms impact. Focus is on investments in generation and transmission power system facilities in regional market. Assumptions include efficient market coupling mechanism (with more bidding zones, use of additional investment indicators (like social welfare and congestion cost and security of supply issues (capacity mechanisms. There is discussion on cost benefits analysis for particular market participants and there is possibility of risk reduction for regional power system expansion. It is shown current state-of-the-art, problems and trends in solving some aspects of market integration and investment issues. In some cases smaller and well defined bidding areas are absolutely essential in order to ensure system security and economic efficiency. There is no single criterion for power system expansion but it is possible to use combination of incentive schemes and possible through one index for cross-border trade. Risk management for cross-border electricity trading through several areas needs to be upgraded with use of financial transmission rights like weighted average area prices, respectively. Regional power system security is closely associated with timely investments in energy supply in line with economic development and environmental needs. Security of supply indicator is deriving an estimation of security of supply improvement from the market based simulation results when a generation or transmission investment project is implemented. All researched makes market integration and investments in Europe more efficient and gives more correct signals to market participants in regional market.

  5. Optimization of mechanical and damping properties of Mg–0.6Zr alloy by different extrusion processing

    Directory of Open Access Journals (Sweden)

    Jingfeng Wang

    2015-03-01

    Full Text Available In this study, the optimization of mechanical and damping capacities of Mg-0.6 wt.% Zr alloys by controlling the recrystallized (DRXed grain size under varying extrusion processing parameters including extrusion temperature T and strain rate ε˙ was investigated. The relationship between the DRXed grain size and damping properties of the studied alloy was also discussed. The DRXed grain size of the as-extruded Mg–Zr alloys decreased as the extrusion temperature T decreased and the strain rate ε˙ increased. As the DRXed grain size decreased, the strength and elongation of the as-extruded alloys exhibited improved performance through the grain refinement mechanism, while the damping properties deteriorated. The extrusion temperature of the Mg–Zr alloy had relatively greater effects on the mechanical and damping properties than the strain rate. The results of the present work indicate that alloys with appropriate mechanical and damping properties may be obtained from controlling the DRXed grain size by careful tailoring of the extrusion process parameters.

  6. A New Mechanism for Maintaining Diversity of Pareto Archive in Multiobjective Optimization

    CERN Document Server

    Hájek, Jaroslav; Šístek, Jakub; 10.1016/j.advengsoft.2010.03.003

    2010-01-01

    The article introduces a new mechanism for selecting individuals to a Pareto archive. It was combined with a micro-genetic algorithm and tested on several problems. The ability of this approach to produce individuals uniformly distributed along the Pareto set without negative impact on convergence is demonstrated on presented results. The new concept was confronted with NSGA-II, SPEA2, and IBEA algorithms from the PISA package. Another studied effect is the size of population versus number of generations for small populations.

  7. Enhanced Efficiency of Thermoelectric Generator by Optimizing Mechanical and Electrical Structures

    Directory of Open Access Journals (Sweden)

    Jinlong Chen

    2017-09-01

    Full Text Available Much attention has been paid to the application of low temperature thermal resources, especially for power generation in recent years. Most of the current commercialized thermal (including geothermal power-generation technologies convert thermal energy to electric energy indirectly, that is, making mechanical work before producing electricity. Technology using a thermoelectric generator (TEG, however, can directly transform thermal energy into electricity through the Seebeck effect. TEG technology has many advantages such as compactness, quietness, and reliability because there are no moving parts. One of the biggest disadvantages of TEGs is the low efficiency from thermal to electric energy. For this reason, we redesigned and modified our previous 1 KW (at a temperature difference of around 120 °C TEG system. The output power of the system was improved significantly, about 34.6% greater; the instantaneous efficiency of the TEG system could reach about 6.5%. Laboratory experiments have been conducted to measure the output power at different conditions: different connection modes between TEG modules, different mechanical structures, and different temperature differences between hot and cold sides. The TEG apparatus has been tested and the data have been presented. This kind of TEG power system can be applied in many thermal and geothermal sites with low temperature resources, including oil fields where fossil and geothermal energies are coproduced.

  8. A Precision-Positioning Method for a High-Acceleration Low-Load Mechanism Based on Optimal Spatial and Temporal Distribution of Inertial Energy

    Directory of Open Access Journals (Sweden)

    Xin Chen

    2015-09-01

    Full Text Available High-speed and precision positioning are fundamental requirements for high-acceleration low-load mechanisms in integrated circuit (IC packaging equipment. In this paper, we derive the transient nonlinear dynamicresponse equations of high-acceleration mechanisms, which reveal that stiffness, frequency, damping, and driving frequency are the primary factors. Therefore, we propose a new structural optimization and velocity-planning method for the precision positioning of a high-acceleration mechanism based on optimal spatial and temporal distribution of inertial energy. For structural optimization, we first reviewed the commonly flexible multibody dynamic optimization using equivalent static loads method (ESLM, and then we selected the modified ESLM for optimal spatial distribution of inertial energy; hence, not only the stiffness but also the inertia and frequency of the real modal shapes are considered. For velocity planning, we developed a new velocity-planning method based on nonlinear dynamic-response optimization with varying motion conditions. Our method was verified on a high-acceleration die bonder. The amplitude of residual vibration could be decreased by more than 20% via structural optimization and the positioning time could be reduced by more than 40% via asymmetric variable velocity planning. This method provides an effective theoretical support for the precision positioning of high-acceleration low-load mechanisms.

  9. Thyroid Scan and Uptake

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    Full Text Available ... uptake are not performed on patients who are pregnant because of the risk of exposing the fetus to radiation. These tests are also not recommended for breastfeeding women. Nuclear medicine procedures can be time consuming. It ...

  10. Thyroid Scan and Uptake

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    Full Text Available ... is taken by mouth, in either liquid or capsule form, it is typically swallowed up to 24 ... I-123 or I-131) in liquid or capsule form to swallow. The thyroid uptake will begin ...

  11. Thyroid Scan and Uptake

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    Full Text Available ... which are encased in metal and plastic and most often shaped like a box, attached to a ... will I experience during and after the procedure? Most thyroid scan and thyroid uptake procedures are painless. ...

  12. Thyroid Scan and Uptake

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    Full Text Available ... scan and uptake uses small amounts of radioactive materials called radiotracers, a special camera and a computer ... last two months that used iodine-based contrast material. Your doctor will instruct you on how to ...

  13. Thyroid Scan and Uptake

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    Full Text Available ... eat for several hours before your exam because eating can affect the accuracy of the uptake measurement. ... often unattainable using other imaging procedures. For many diseases, nuclear medicine scans yield the most useful information ...

  14. Thyroid Scan and Uptake

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    Full Text Available ... RAIU) is also known as a thyroid uptake. It is a measurement of thyroid function, but does ... they offer the potential to identify disease in its earliest stages as well as a patient’s immediate ...

  15. Thyroid Scan and Uptake

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    Full Text Available ... time for the imaging to begin, you will sit in a chair facing a stationary probe positioned ... counter used for thyroid uptake exams. The patient sits with the camera directed at the neck for ...

  16. Thyroid Scan and Uptake

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    Full Text Available ... for several hours before your exam because eating can affect the accuracy of the uptake measurement. Jewelry ... small hand-held device resembling a microphone that can detect and measure the amount of the radiotracer ...

  17. Thyroid Scan and Uptake

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    Full Text Available ... information about your thyroid’s size, shape, position and function that is often unattainable using other imaging procedures. ... thyroid uptake. It is a measurement of thyroid function, but does not involve imaging. Nuclear medicine is ...

  18. Thyroid Scan and Uptake

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    Full Text Available ... A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) is ... thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that uses ...