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Sample records for mechanical activation assisted

  1. Mechanical Activation-Assisted Reductive Leaching of Cadmium from Zinc Neutral Leaching Residue Using Sulfur Dioxide

    NASA Astrophysics Data System (ADS)

    Zhang, Chun; Min, Xiaobo; Chai, Liyuan; Zhang, Jianqiang; Wang, Mi

    2015-12-01

    In this work, zinc neutral leaching residue was mechanically activated by ball-milling. The subsequent leaching behavior and kinetics of cadmium extraction in a mixed SO2-H2SO4 system were studied. Changes in the crystalline phase, lattice distortion, particle size and morphology, which were induced by mechanical activation, were also investigated. The activated samples showed different physicochemical characteristics, and cadmium extraction was found to be easier than for the un-activated samples. Under the same conditions, mechanical activation contributed to higher cadmium leaching. The cadmium extraction kinetics at 75-95°C was found to fit the shrinking core model. The raw neutral leaching residue, and the samples activated for 60 min and 120 min had a calculated activation energy of 65.02 kJ/mol, 59.45 kJ/mol and 53.46 kJ/mol, respectively. The leaching residue was characterized by ICP, XRD and SEM analysis. According to XRD analysis, the main phases in the residue were lead sulfate (PbSO4), zinc sulfide (ZnS) and cadmium sulfide (CdS).

  2. A Substrate-Assisted Mechanism of Nucleophile Activation in a Ser-His-Asp Containing C-C Bond Hydrolase

    SciTech Connect

    Ruzzini, Antonio C.; Bhowmik, Shiva; Ghosh, Subhangi; Yam, Katherine C.; Bolin, Jeffrey T.; Eltis, Lindsay D.

    2013-11-12

    The meta-cleavage product (MCP) hydrolases utilize a Ser–His–Asp triad to hydrolyze a carbon–carbon bond. Hydrolysis of the MCP substrate has been proposed to proceed via an enol-to-keto tautomerization followed by a nucleophilic mechanism of catalysis. Ketonization involves an intermediate, ESred, which possesses a remarkable bathochromically shifted absorption spectrum. We investigated the catalytic mechanism of the MCP hydrolases using DxnB2 from Sphingomonas wittichii RW1. Pre-steady-state kinetic and LC ESI/MS evaluation of the DxnB2-mediated hydrolysis of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid to 2-hydroxy-2,4-pentadienoic acid and benzoate support a nucleophilic mechanism catalysis. In DxnB2, the rate of ESred decay and product formation showed a solvent kinetic isotope effect of 2.5, indicating that a proton transfer reaction, assigned here to substrate ketonization, limits the rate of acylation. For a series of substituted MCPs, this rate was linearly dependent on MCP pKa2nuc ~ 1). Structural characterization of DxnB2 S105A:MCP complexes revealed that the catalytic histidine is displaced upon substrate-binding. The results provide evidence for enzyme-catalyzed ketonization in which the catalytic His–Asp pair does not play an essential role. The data further suggest that ESred represents a dianionic intermediate that acts as a general base to activate the serine nucleophile. This substrate-assisted mechanism of nucleophilic catalysis distinguishes MCP hydrolases from other serine hydrolases.

  3. Diaphragmatic contraction during assisted mechanical ventilation.

    PubMed

    Flick, G R; Bellamy, P E; Simmons, D H

    1989-07-01

    Indirect evidence from airway pressure recordings in mechanically ventilated patients suggests that the diaphragm exhibits contractile activity beyond that required to trigger a ventilator-assisted breath. We used the diaphragmatic EMG to provide direct evidence of persistent contractile activity and studied the effects of alterations in ventilator-delivered flow rate and tidal volume on the duration of diaphragmatic contraction. The duration of contraction was expressed in terms of inspired volume. During a single breath, diaphragmatic force generation ceases at the point of peak electromyographic activity; hence, the inspired volume at peak EMG is the volume at the diaphragmatic off-switch (Voff). Ventilator-delivered flow rate and tidal volume were varied during assisted (patient-initiated) and controlled (ventilator-initiated) breaths while diaphragmatic EMG and inspired volume were recorded simultaneously in ten patients with a variety of illnesses requiring mechanical ventilation. Spontaneous ventilator-unassisted breaths were also recorded for comparison. We found that (1) during assisted breaths, diaphragmatic activity continued after the ventilator was triggered, (2) Voff was usually close to spontaneous tidal volume, (3) Voff increased significantly as ventilator-delivered flow rate increased, and (4) controlled breaths may also be associated with phasic electromyographic activity. The data have implications for resting patients on assisted ventilation.

  4. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, Arnold R.

    1987-01-01

    There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing he evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

  5. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, A.R.

    1987-11-24

    There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator. 5 figs.

  6. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, Arnold R.

    1987-01-01

    There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

  7. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, A.R.

    1987-06-23

    There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator. 5 figs.

  8. Assessing the Relative Contributions of Active Ankle and Knee Assistance to the Walking Mechanics of Transfemoral Amputees Using a Powered Prosthesis

    PubMed Central

    Simon, Ann M.; Hargrove, Levi J.

    2016-01-01

    Powered knee-ankle prostheses are capable of providing net-positive mechanical energy to amputees. Yet, there are limitless ways to deliver this energy throughout the gait cycle. It remains largely unknown how different combinations of active knee and ankle assistance affect the walking mechanics of transfemoral amputees. This study assessed the relative contributions of stance phase knee swing initiation, increasing ankle stiffness and powered plantarflexion as three unilateral transfemoral amputees walked overground at their self-selected walking speed. Five combinations of knee and ankle conditions were evaluated regarding the kinematics and kinetics of the amputated and intact legs using repeated measures analyses of variance. We found eliminating active knee swing initiation or powered plantarflexion was linked to increased compensations of the ipsilateral hip joint during the subsequent swing phase. The elimination of knee swing initiation or powered plantarflexion also led to reduced braking ground reaction forces of the amputated and intact legs, and influenced both sagittal and frontal plane loading of the intact knee joint. Gradually increasing prosthetic ankle stiffness influenced the shape of the prosthetic ankle plantarflexion moment, more closely mirroring the intact ankle moment. Increasing ankle stiffness also corresponded to increased prosthetic ankle power generation (despite a similar maximum stiffness value across conditions) and increased braking ground reaction forces of the amputated leg. These findings further our understanding of how to deliver assistance with powered knee-ankle prostheses and the compensations that occur when specific aspects of assistance are added/removed. PMID:26807889

  9. Assessing the Relative Contributions of Active Ankle and Knee Assistance to the Walking Mechanics of Transfemoral Amputees Using a Powered Prosthesis.

    PubMed

    Ingraham, Kimberly A; Fey, Nicholas P; Simon, Ann M; Hargrove, Levi J

    2016-01-01

    Powered knee-ankle prostheses are capable of providing net-positive mechanical energy to amputees. Yet, there are limitless ways to deliver this energy throughout the gait cycle. It remains largely unknown how different combinations of active knee and ankle assistance affect the walking mechanics of transfemoral amputees. This study assessed the relative contributions of stance phase knee swing initiation, increasing ankle stiffness and powered plantarflexion as three unilateral transfemoral amputees walked overground at their self-selected walking speed. Five combinations of knee and ankle conditions were evaluated regarding the kinematics and kinetics of the amputated and intact legs using repeated measures analyses of variance. We found eliminating active knee swing initiation or powered plantarflexion was linked to increased compensations of the ipsilateral hip joint during the subsequent swing phase. The elimination of knee swing initiation or powered plantarflexion also led to reduced braking ground reaction forces of the amputated and intact legs, and influenced both sagittal and frontal plane loading of the intact knee joint. Gradually increasing prosthetic ankle stiffness influenced the shape of the prosthetic ankle plantarflexion moment, more closely mirroring the intact ankle moment. Increasing ankle stiffness also corresponded to increased prosthetic ankle power generation (despite a similar maximum stiffness value across conditions) and increased braking ground reaction forces of the amputated leg. These findings further our understanding of how to deliver assistance with powered knee-ankle prostheses and the compensations that occur when specific aspects of assistance are added/removed.

  10. Computer Assisted Introduction to Mechanics.

    ERIC Educational Resources Information Center

    Huggins, Elisha R.

    These six chapters provide an introduction to Newtonian mechanics, based on a coordinated use of text material, laboratory work, and the computer. The material is essentially self-contained so that it can serve as a short text on mechanics or as a text supplement in a regular physics course. Chapter 1 is a brief introduction to the computer…

  11. The celestial mechanics of gravity assist

    NASA Astrophysics Data System (ADS)

    Broucke, R. A.

    The celestial mechanics and fundamental principles of the gravity-assist phenomenon are discussed, and the most important situations are classified on the basis of the most simple meaningful models: the two-body problem and numerical integrations of the restricted three-body problem. The basic geometry of the velocity-vector additions involved are first reviewed. Many of the geometric results are obtained analytically, and the 'best' gravity-assist possible is sought. Emphasis is placed on the fundamental role played by the Jacobi integral in the restricted problem, and in the gravity-assist in particular. In the present study, the equations of motion are fully regularized.

  12. Integrated mechanism design with artificial intelligence assistance

    SciTech Connect

    Bohatier, C.; Silberberg, Y.; Guillot, J.

    1996-11-01

    The proposed design methodology is developed as an integrated process in the production process. A setup of design workshop is suggested. An original functional approach is proposed. Its implementation using artificial intelligence is performed by an expert system generator. This intelligent assistance prototype is open to other aided computer engineering fields. Finally, an application to mechanism design is presented.

  13. New modes of assisted mechanical ventilation.

    PubMed

    Suarez-Sipmann, F

    2014-05-01

    Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes.

  14. New modes of assisted mechanical ventilation.

    PubMed

    Suarez-Sipmann, F

    2014-05-01

    Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes. PMID:24507472

  15. Gravity-Assist Mechanical Simulator for Outreach

    NASA Technical Reports Server (NTRS)

    Doody, David F.; White, Victor E.; Schaff, Mitch D.

    2012-01-01

    There is no convenient way to demonstrate mechanically, as an outreach (or inreach) topic, the angular momentum trade-offs and the conservation of angular momentum associated with gravityassist interplanetary trajectories. The mechanical concepts that underlie gravity assist are often misunderstood or confused, possibly because there is no mechanical analog to it in everyday experience. The Gravity Assist Mech - anical Simulator is a hands-on solution to this longstanding technical communications challenge. Users intuitively grasp the concepts, meeting specific educational objectives. A manually spun wheel with high angular mass and low-friction bearings supplies momentum to an attached spherical neodymium magnet that represents a planet orbiting the Sun. A steel bearing ball following a trajectory across a glass plate above the wheel and magnet undergoes an elastic collision with the revolving magnet, illustrating the gravitational elastic collision between spacecraft and planet on a gravity-assist interplanetary trajectory. Manually supplying the angular momentum for the elastic collision, rather than observing an animation, intuitively conveys the concepts, meeting nine specific educational objectives. Many NASA and JPL interplanetary missions are enabled by the gravity-assist technique.

  16. New modes of mechanical ventilation: proportional assist ventilation, neurally adjusted ventilatory assist, and fractal ventilation.

    PubMed

    Navalesi, Paolo; Costa, Roberta

    2003-02-01

    Increased knowledge of the mechanisms that determine respiratory failure has led to the development of new technologies aimed at improving ventilatory treatment. Proportional assist ventilation and neurally adjusted ventilatory assist have been designed with the goal of improving patient-ventilator interaction by matching the ventilator support with the neural output of the respiratory centers. With proportional assist ventilation, the support is continuously readjusted in proportion to the predicted inspiratory effort. Neurally adjusted ventilatory assist is an experimental mode in which the assistance is delivered in proportion to the electrical activity of the diaphragm, assessed by means of an esophageal electrode. Biologically variable (or fractal) ventilation is a new, volume-targeted, controlled ventilation mode aimed at improving oxygenation; it incorporates the breath-to-breath variability that characterizes a natural breathing pattern.

  17. Spatially Assisted Schwinger Mechanism and Magnetic Catalysis

    NASA Astrophysics Data System (ADS)

    Copinger, Patrick; Fukushima, Kenji

    2016-08-01

    Using the worldline formalism we compute an effective action for fermions under a temporally modulated electric field and a spatially modulated magnetic field. It is known that the former leads to an enhanced Schwinger mechanism, while we find that the latter can also result in enhanced particle production and even cause a reorganization of the vacuum to acquire a larger dynamical mass in equilibrium which spatially assists the magnetic catalysis.

  18. Spatially Assisted Schwinger Mechanism and Magnetic Catalysis.

    PubMed

    Copinger, Patrick; Fukushima, Kenji

    2016-08-19

    Using the worldline formalism we compute an effective action for fermions under a temporally modulated electric field and a spatially modulated magnetic field. It is known that the former leads to an enhanced Schwinger mechanism, while we find that the latter can also result in enhanced particle production and even cause a reorganization of the vacuum to acquire a larger dynamical mass in equilibrium which spatially assists the magnetic catalysis. PMID:27588845

  19. Computer Assisted Mechanical Axis and Kinematic TKA

    PubMed Central

    McEwen, Peter; Mahoharan, Varaguna

    2016-01-01

    Introduction: Total knee arthroplasty (TKA) has traditionally been and largely continues to be aligned mechanically, that being with a neutral coronal plane mechanical tibiofemoral axis and a joint line orientated at 900 to this axis. Femoral component rotation is set by gap balancing or by externally rotating 30 from any of a number femoral reference lines. This produces a rectangular flexion gap and relaxes patellar tracking. Kinematic alignment (KA) is an alternative technique that aims to restore premorbid alignment, joint orientation and ligament tension. The basic premise for this technique is based on evidence that the medial and lateral femoral condyles consistently equate to cylinders of equal or near equal size and that therefore with a fixed radius, cruciate retaining implant, matched distal femoral, posterior femoral and proximal tibial resections, accounting for bone and cartilage already lost will reproduce the premorbid joint line and restore native premorbid kinematics. Femoral rotation is therefore referenced off the prearthritic posterior condylar axis (PCA) that is on average internally rotated to the AP axis. Kinematic alignment therefore has the potential to challenge patellar tracking, increase patellar load and potentially increase patellar complications. Method: Case control study – level of evidence III-2. Between November 2012 and June 2013 the senior author completed 104 consecutive computer assisted (CAS) kinematically aligned total knee arthroplasties (TKA) with a cruciate retaining, fixed bearing, single radius implant. The results of these surgeries were compared with the results of 91 consecutive CAS mechanically aligned TKA done between November 2011 and October 2012 using the same navigation system and implant Implant sizing and positioning as well as gap measurement and ligament balance was done with computer assistance in all cases. Data was collected prospectively and analysed retrospectively. Results: The Oxford Knee Score

  20. Mechanically Activated Ion Channels

    PubMed Central

    Ranade, Sanjeev S.; Syeda, Ruhma; Patapoutian, Ardem

    2015-01-01

    Mechanotransduction, the conversion of physical forces into biochemical signals, is an essential component of numerous physiological processes including not only conscious senses of touch and hearing, but also unconscious senses such as blood pressure regulation. Mechanically activated (MA) ion channels have been proposed as sensors of physical force, but the identity of these channels and an understanding of how mechanical force is transduced has remained elusive. A number of recent studies on previously known ion channels along with the identification of novel MA ion channels have greatly transformed our understanding of touch and hearing in both vertebrates and invertebrates. Here, we present an updated review of eukaryotic ion channel families that have been implicated in mechanotransduction processes and evaluate the qualifications of the candidate genes according to specified criteria. We then discuss the proposed gating models for MA ion channels and highlight recent structural studies of mechanosensitive potassium channels. PMID:26402601

  1. Active gated imaging in driver assistance system

    NASA Astrophysics Data System (ADS)

    Grauer, Yoav

    2014-04-01

    In this paper, we shall present the active gated imaging system (AGIS) in relation to the automotive field. AGIS is based on a fast-gated camera and pulsed illuminator, synchronized in the time domain to record images of a certain range of interest. A dedicated gated CMOS imager sensor and near infra-red (NIR) pulsed laser illuminator, is presented in this paper to provide active gated technology. In recent years, we have developed these key components and learned the system parameters, which are most beneficial to nighttime (in all weather conditions) driving in terms of field of view, illumination profile, resolution, and processing power. We shall present our approach of a camera-based advanced driver assistance systems (ADAS) named BrightEye™, which makes use of the AGIS technology in the automotive field.

  2. Subchronic centrifugal mechanical assist in an unheparinized calf model.

    PubMed

    Wagner-Mann, C; Curtis, J; Mann, F A; Turk, J; Demmy, T; Turpin, T

    1996-06-01

    The purpose of this study was to determine whether the major centrifugal pumps currently in use in the United States (Medtronic, BioMedicus BioPump and Carmeda-coated BioPump, Sarns 3M centrifugal pump, and St. Jude Medical Lifestream) could function as left mechanical assist devices in the subchronic (72 h) unheparinized calf model. Calves were instrumented for left atrial to aorta ex vivo assist, and the pump flow was set at 3.5 +/- 0.4 L/min. Two calves (Sarns 3M and St. Jude) survived 72 h of pumping without clinical complications. The other 2 calves died at 62 and 66 h (Medtronic BioPump and Carmeda-coated BioPump, respectively); both had pelvic limb paralysis. The seal of the Sarns 3M pump head ruptured after approximately 36 h of pumping and required replacement. On postmortem examination, pump-associated thromboembolic lesions were detected in 3 of the 4 calves in one or more of the following organs: kidneys, pancreas, abomasum, duodenum, ileum, spleen, and lumbar spinal cord. The calf with the Sarns 3M pump had no discernable lesions. Because of the clinical abnormalities and postmortem lesions in the unheparinized calf model, it was suggested that anticoagulation is necessary for conducting centrifugal mechanical assist studies in calves using presently available technology.

  3. [Importance of mechanical assist devices in acute circulatory arrest].

    PubMed

    Ferrari, Markus Wolfgang

    2016-03-01

    Mechanical assist devices are indicated for hemodynamic stabilization in acute circulatory arrest if conventional means of cardiopulmonary resuscitation are unable to re-establish adequate organ perfusion. Their temporary use facilitates further diagnostic and therapeutic options in selected patients, e.g. coronary angiography followed by revascularization.External thorax compression devices allow sufficient cardiac massage in case of preclinical or in-hospital circulatory arrest, especially under complex transfer conditions. These devices perform standardized thorax compressions at a rate of 80-100 per minute. Invasive mechanical support devices are used in the catheter laboratory or in the intensive care unit. Axial turbine pumps, e.g. the Impella, continuously pump blood from the left ventricle into the aortic root. The Impella can also provide right ventricle support by pumping blood from the vena cava into the pulmonary artery. So-called emergency systems or ECMO devices consist of a centrifugal pump and a membrane oxygenator allowing complete takeover of cardiac and pulmonary functions. Withdrawing blood from the right atrium and vena cava, oxygenated blood is returned to the abdominal aorta. Isolated centrifugal pumps provide left heart support without an oxygenator after transseptal insertion of a venous cannula into the left atrium.Mechanical assist devices are indicated for acute organ protection and hemodynamic stabilization for diagnostic and therapeutic measures as well as bridge to myocardial recovery. Future technical developments and better insights into the pathophysiology of mechanical circulatory support will broaden the spectrum of indications of such devices in acute circulatory arrest. PMID:26860409

  4. Effects of Equine Assisted Activities on Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Lanning, Beth A.; Baier, Margaret E. Matyastik; Ivey-Hatz, Julie; Krenek, Nancy; Tubbs, Jack D.

    2014-01-01

    Quality of life assessments were used in this study to determine the behavioral changes of children diagnosed with autism spectrum disorder (ASD) who participated in equine assisted activities. Behavioral changes of children with ASD participating in 9 weeks of equines assisted activities (EAA) (N = 10) were compared to behavioral changes of…

  5. Computer simulation of the mechanically-assisted failing canine circulation.

    PubMed

    Barnea, O; Moore, T W; Jaron, D

    1990-01-01

    A model of the cardiovascular system is presented. The model includes representations of the left and right ventricles, a nonlinear multielement model of the aorta and its main branches, and lumped models of the systemic veins and the pulmonary circulation. A simulation of the intra-aortic balloon pump and representations of physiological compensatory mechanisms are also incorporated in the model. Parameters of the left ventricular model were set to simulate either the normal or failing canine circulation. Pressure and flow waveforms throughout the circulation as well as ventricular pressure and volume were calculated for the normal, failing, and assisted failing circulation. Cardiac oxygen supply and consumption were calculated from the model. They were used as direct indices of cardiac energy supply and utilization to assess the effects of cardiac assistance.

  6. Neuroreceptor Activation by Vibration-Assisted Tunneling

    PubMed Central

    Hoehn, Ross D.; Nichols, David; Neven, Hartmut; Kais, Sabre

    2015-01-01

    G protein-coupled receptors (GPCRs) constitute a large family of receptor proteins that sense molecular signals on the exterior of a cell and activate signal transduction pathways within the cell. Modeling how an agonist activates such a receptor is fundamental for an understanding of a wide variety of physiological processes and it is of tremendous value for pharmacology and drug design. Inelastic electron tunneling spectroscopy (IETS) has been proposed as a model for the mechanism by which olfactory GPCRs are activated by a bound agonist. We apply this hyothesis to GPCRs within the mammalian nervous system using quantum chemical modeling. We found that non-endogenous agonists of the serotonin receptor share a particular IET spectral aspect both amongst each other and with the serotonin molecule: a peak whose intensity scales with the known agonist potencies. We propose an experiential validation of this model by utilizing lysergic acid dimethylamide (DAM-57), an ergot derivative, and its deuterated isotopologues; we also provide theoretical predictions for comparison to experiment. If validated our theory may provide new avenues for guided drug design and elevate methods of in silico potency/activity prediction. PMID:25909758

  7. Neuroreceptor activation by vibration-assisted tunneling.

    PubMed

    Hoehn, Ross D; Nichols, David; Neven, Hartmut; Kais, Sabre

    2015-01-01

    G protein-coupled receptors (GPCRs) constitute a large family of receptor proteins that sense molecular signals on the exterior of a cell and activate signal transduction pathways within the cell. Modeling how an agonist activates such a receptor is fundamental for an understanding of a wide variety of physiological processes and it is of tremendous value for pharmacology and drug design. Inelastic electron tunneling spectroscopy (IETS) has been proposed as a model for the mechanism by which olfactory GPCRs are activated by a bound agonist. We apply this hyothesis to GPCRs within the mammalian nervous system using quantum chemical modeling. We found that non-endogenous agonists of the serotonin receptor share a particular IET spectral aspect both amongst each other and with the serotonin molecule: a peak whose intensity scales with the known agonist potencies. We propose an experiential validation of this model by utilizing lysergic acid dimethylamide (DAM-57), an ergot derivative, and its deuterated isotopologues; we also provide theoretical predictions for comparison to experiment. If validated our theory may provide new avenues for guided drug design and elevate methods of in silico potency/activity prediction. PMID:25909758

  8. Mechanically Active Electrospun Materials

    NASA Astrophysics Data System (ADS)

    Robertson, Jaimee M.

    Electrospinning, a technique used to fabricate small diameter polymer fibers, has been employed to develop unique, active materials falling under two categories: (1) shape memory elastomeric composites (SMECs) and (2) water responsive fiber mats. (1) Previous work has characterized in detail the properties and behavior of traditional SMECs with isotropic fibers embedded in an elastomer matrix. The current work has two goals: (i) characterize laminated anisotropic SMECs and (ii) develop a fabrication process that is scalable for commercial SMEC manufacturing. The former ((i)) requires electrospinning aligned polymer fibers. The aligned fibers are similarly embedded in an elastomer matrix and stacked at various fiber orientations. The resulting laminated composite has a unique response to tensile deformation: after stretching and releasing, the composite curls. This curling response was characterized based on fiber orientation. The latter goal ((ii)) required use of a dual-electrospinning process to simultaneously electrospin two polymers. This fabrication approach incorporated only industrially relevant processing techniques, enabling the possibility of commercial application of a shape memory rubber. Furthermore, the approach had the added benefit of increased control over composition and material properties. (2) The strong elongational forces experienced by polymer chains during the electrospinning process induce molecular alignment along the length of electrospun fibers. Such orientation is maintained in the fibers as the polymer vitrifies. Consequently, residual stress is stored in electrospun fiber mats and can be recovered by heating through the polymer's glass transition temperature. Alternatively, the glass transition temperature can be depressed by introducing a plasticizing agent. Poly(vinyl acetate) (PVAc) is plasticized by water, and its glass transition temperature is lowered below room temperature. Therefore, the residual stress can be relaxed at room

  9. Environment assisted degradation mechanisms in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Stoner, Glenn E.; Swanson, Robert E.

    1988-01-01

    Section 1 of this report records the progress achieved on NASA-LaRC Grant NAG-1-745 (Environment Assisted Degradation Mechanisms in Al-Li Alloys), and is based on research conducted during the period April 1 to November 30, 1987. A discussion of work proposed for the project's second year is included. Section 2 provides an overview of the need for research on the mechanisms of environmental-mechanical degradation of advanced aerospace alloys based on aluminum and lithium. This research is to provide NASA with the basis necessary to permit metallurgical optimization of alloy performance and engineering design with respect to damage tolerance, long term durability and reliability. Section 3 reports on damage localization mechanisms in aqueous chloride corrosion fatigue of aluminum-lithium alloys. Section 4 reports on progress made on measurements and mechanisms of localized aqueous corrosion in aluminum-lithium alloys. Section 5 provides a detailed technical proposal for research on environmental degradation of Al-Li alloys, and the effect of hydrogen in this.

  10. Active Auditory Mechanics in Insects

    NASA Astrophysics Data System (ADS)

    Robert, D.; Göpfert, M. C.

    2003-02-01

    Evidence is presented that hearing in some insects is an active process. Audition in mosquitoes is used for mate-detection and is supported by antennal receivers, whose sound-induced vibrations are transduced by Johnston's organs. Each of these sensory organs contains ca. 15,000 sensory neurons. As shown by mechanical analysis, a physiologically vulnerable mechanism is at work that nonlinearly enhances the sensitivity and frequency selectivity of antennal hearing. This process of amplification correlates with the electrical activity of the auditory mechanoreceptor units in Johnston's organ.

  11. A mechanically assisted heat pipe using micro-pumps

    SciTech Connect

    Wong, J.L.; Campbell, G.; Hassapis, C.; Chang, W.S.

    1996-12-31

    A new mechanically assisted heat pipe has been developed and tested by the authors that combines the high performance of a pumped fluid loop with the reliability of passive heat pipes. The new unit employs micro-pumps inside a passive heat pipe to enhance the return of working fluid from the condenser to the evaporator, and thereby increases the capability of the system. This hybrid device is lighter, smaller and handles higher heat flux compared with a passive heat pipe of similar weight and dimensions. Best of all, if the mechanical pump fails, the heat transport will be impaired, but not totally paralyzed, allowing some form of lower level operation. This micro-pump design installs fins at critical locations inside the heat pipe. These fins can be parallel (flag) or perpendicular (flap) to the flow direction. By vibrating these fins in a motion similar to dolphin kicks for the flaps, and in a motion similar to a fishtail for the flags, these fins were found capable of pumping the working fluid effectively. The size and geometry of these fins were tested extensively. Several actuation approaches were examined. The results of these tests are presented in this paper.

  12. Ultrasonic flexural vibration assisted chemical mechanical polishing for sapphire substrate

    NASA Astrophysics Data System (ADS)

    Xu, Wenhu; Lu, Xinchun; Pan, Guoshun; Lei, Yuanzhong; Luo, Jianbin

    2010-04-01

    The sapphire substrates are polished by traditional chemical mechanical polishing (CMP) and ultrasonic flexural vibration (UFV) assisted CMP (UFV-CMP) respectively with different pressures. UFV-CMP combines the functions of traditional CMP and ultrasonic machining (USM) and has special characteristics, which is that ultrasonic vibrations of the rotating polishing head are in both horizontal and vertical directions. The material removal rates (MRRs) and the polished surface morphology of CMP and UFV-CMP are compared. The MRR of UFV-CMP is two times larger than that of traditional CMP. The surface roughness (root mean square, RMS) of the polished sapphire substrate of UFV-CMP is 0.83 Å measured by the atomic force microscopy (AFM), which is much better than 2.12 Å obtained using the traditional CMP. And the surface flatness of UFV-CMP is 0.12 μm, which is also better than 0.23 μm of the traditional CMP. The results show that UFV-CMP is able to improve the MRR and finished surface quality of the sapphire substrates greatly. The material removal and surface polishing mechanisms of sapphire in UFV-CMP are discussed too.

  13. Performance Assessment Assistance Activities in the DOE Complex - 12325

    SciTech Connect

    Seitz, Roger R.; Phifer, Mark A.; Letourneau, Martin J.

    2012-07-01

    The United States Department of Energy Office of Environmental Management (DOE-EM) has established a Performance Assessment Community of Practice (PA CoP) to foster the sharing of information among performance assessment (PA) and risk assessment practitioners, regulators and oversight personnel. The general intent is to contribute to continuous improvement in the consistency, technical adequacy and quality of implementation of PAs and risk assessments around the DOE Complex. The PA CoP activities have involved commercial disposal facilities and international participants to provide a global perspective. The PA CoP has also sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from on-going modelling activities. The PA CoP encourages activities to provide programmatic and technical assistance in the form of sharing experience and lessons learned with practitioners during the development of PAs and risk assessments. This assistance complements DOE-EM reviews through the Low-Level Waste Disposal Facility Federal Review Group (LFRG) that are conducted after modelling efforts are completed. Such up-front assistance is providing additional value in terms of improving consistency and sharing of information. There has been a substantial increase in the amount of assistance being provided. The assistance has been well received by practitioners and regulators that have been involved. The paper highlights assistance and sharing of information that has been conducted in the last two years to support activities underway in support of proposed disposal facilities at Paducah, Portsmouth, and the Idaho National Laboratory and tank closure at Hanford. DOE-EM established the PA CoP to help improve the consistency and quality of implementation of modelling activities around the DOE Complex. The PA CoP has sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from ongoing

  14. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons.

  15. Active motion assisted by correlated stochastic torques.

    PubMed

    Weber, Christian; Radtke, Paul K; Schimansky-Geier, Lutz; Hänggi, Peter

    2011-07-01

    The stochastic dynamics of an active particle undergoing a constant speed and additionally driven by an overall fluctuating torque is investigated. The random torque forces are expressed by a stochastic differential equation for the angular dynamics of the particle determining the orientation of motion. In addition to a constant torque, the particle is supplemented by random torques, which are modeled as an Ornstein-Uhlenbeck process with given correlation time τ(c). These nonvanishing correlations cause a persistence of the particles' trajectories and a change of the effective spatial diffusion coefficient. We discuss the mean square displacement as a function of the correlation time and the noise intensity and detect a nonmonotonic dependence of the effective diffusion coefficient with respect to both correlation time and noise strength. A maximal diffusion behavior is obtained if the correlated angular noise straightens the curved trajectories, interrupted by small pirouettes, whereby the correlated noise amplifies a straightening of the curved trajectories caused by the constant torque.

  16. PERFORMANCE ASSESSMENT ASSISTANCE ACTIVITIES IN THE DOE COMPLEX

    SciTech Connect

    Seitz, R.

    2012-01-23

    The United States Department of Energy Office of Environmental Management (DOE-EM) has established a Performance Assessment Community of Practice (PA CoP) to foster the sharing of information among performance assessment (PA) and risk assessment practitioners, regulators and oversight personnel. The general intent is to contribute to continuous improvement in the consistency, technical adequacy and quality of implementation of PAs and risk assessments around the DOE Complex. The PA CoP activities have involved commercial disposal facilities and international participants to provide a global perspective. The PA CoP has also sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from on-going modelling activities. The PA CoP encourages activities to provide programmatic and technical assistance in the form of sharing experience and lessons learned with practitioners during the development of PAs and risk assessments. This assistance complements DOE-EM reviews through the Low-Level Waste Disposal Facility Federal Review Group (LFRG) that are conducted after modelling efforts are completed. Such up-front assistance is providing additional value in terms of improving consistency and sharing of information. There has been a substantial increase in the amount of assistance being provided. The assistance has been well received by practitioners and regulators that have been involved. The paper highlights assistance and sharing of information that has been conducted in the last two years to support activities underway in support of proposed disposal facilities at Paducah, Portsmouth, and the Idaho National Laboratory and tank closure at Hanford.

  17. 78 FR 64414 - Assistance to Foreign Atomic Energy Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-29

    ... concerning Assistance to Foreign Atomic Energy Activities since 1986. (76 FR 55278) The NOPR reflected a need.... ] DATES: DOE will continue to accept written comments on the SNOPR published August 2, 2013 (78 FR 46829... a second opportunity to comment. (78 FR 46829) II. Second Public Meeting A public meeting on...

  18. 76 FR 65634 - Assistance to Foreign Atomic Energy Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-24

    ... Proposed Rulemaking (76 FR 55278). FOR FURTHER INFORMATION CONTACT: Richard Goorevich, National Nuclear Security Administration, U.S. Department of Energy, Office of Defense Nuclear Nonproliferation (NA-20... assistance to foreign atomic energy activities (76 FR 55278). This regulation provides that persons...

  19. 21 CFR 890.5050 - Daily activity assist device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Daily activity assist device. 890.5050 Section 890.5050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5050 Daily...

  20. 21 CFR 890.5050 - Daily activity assist device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Daily activity assist device. 890.5050 Section 890.5050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5050 Daily...

  1. 21 CFR 890.5050 - Daily activity assist device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Daily activity assist device. 890.5050 Section 890.5050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5050 Daily...

  2. 21 CFR 890.5050 - Daily activity assist device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Daily activity assist device. 890.5050 Section 890.5050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5050 Daily...

  3. 21 CFR 890.5050 - Daily activity assist device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Daily activity assist device. 890.5050 Section 890.5050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5050 Daily...

  4. MR-compatible hand exoskeleton for monitoring brain activity during active assistance.

    PubMed

    Kim, Sangjoon J; Jung Kim

    2015-08-01

    This work presents the mechanical design, implementation and evaluation of an MR-compatible hand exoskeleton that provides real-time monitoring of the joint angle, angular velocity and joint force produced by the MCP joint of the four fingers in an fMRI scanner. For force measurement, a novel optical type force sensor has been designed and implemented. The proposed hand exoskeleton is also capable of providing computer controlled assistive and resistive forces to the MCP joints using a non-magnetic ultrasonic motor, which allows the investigation of the brain activity during both passive (non-voluntary) and active (voluntary) movements. The MR-compatibility of the system was verified based on the analysis of SNR images of phantom tests and by the acquisition of human brain images.

  5. 77 FR 67804 - Agency Information Collection Activities; Comment Request; Application for Client Assistance Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-14

    ... Agency Information Collection Activities; Comment Request; Application for Client Assistance Program... notice will be considered public records. Title of Collection: Application for Client Assistance Program... request funds to establish and carry out Client Assistance Programs (CAP). CAP is mandated by...

  6. 76 FR 44090 - Proposed Information Collection (Application for Individualized Tutorial Assistance) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ... AFFAIRS Proposed Information Collection (Application for Individualized Tutorial Assistance) Activity... solicits comments on the information needed to determine an applicant's eligibility for tutorial assistance.... Title: Application for Individualized Tutorial Assistance, VA Form 22-1990t. ] OMB Control Number:...

  7. [Active euthanasia in Colombia and assisted suicide in California].

    PubMed

    Julesz, Máté

    2016-01-31

    The institution of active euthanasia has been legal in Colombia since 2015. In California, the regulation on physician-assisted suicide will come into effect on January 1, 2016. The legal institution of active euthanasia is not accepted under the law of the United States of America, however, physician-assisted suicide is accepted in an increasing number of member states. The related regulation in Oregon is imitated in other member states. In South America, Colombia is not the first country to legalize active euthanasia: active euthanasia has been legal in Uruguay since 1932. The North American legal tradition markedly differs from the South American one and both are incompatible with the Central European rule of law. In Hungary and in most European Union countries, solely the passive form of euthanasia is legal. In the Benelux countries, the active form of euthanasia is legal because the supranational law of the European Union does not prohibit it. Notwithstanding, European Union law does not prescribe legalization of either the active form of euthanasia, or the physician-assisted suicide. PMID:26801362

  8. [Active euthanasia in Colombia and assisted suicide in California].

    PubMed

    Julesz, Máté

    2016-01-31

    The institution of active euthanasia has been legal in Colombia since 2015. In California, the regulation on physician-assisted suicide will come into effect on January 1, 2016. The legal institution of active euthanasia is not accepted under the law of the United States of America, however, physician-assisted suicide is accepted in an increasing number of member states. The related regulation in Oregon is imitated in other member states. In South America, Colombia is not the first country to legalize active euthanasia: active euthanasia has been legal in Uruguay since 1932. The North American legal tradition markedly differs from the South American one and both are incompatible with the Central European rule of law. In Hungary and in most European Union countries, solely the passive form of euthanasia is legal. In the Benelux countries, the active form of euthanasia is legal because the supranational law of the European Union does not prohibit it. Notwithstanding, European Union law does not prescribe legalization of either the active form of euthanasia, or the physician-assisted suicide.

  9. Low energy ion assisted carbon film growth: Methods and mechanisms

    NASA Astrophysics Data System (ADS)

    Ullmann, Jens

    1997-05-01

    Hydrogen-free amorphous carbon films (a-C) prepared by different ion assisted methods (i) ion assisted evaporation (IAE), (ii) unbalanced magnetron sputtering (MS), (iii) mass separated ion beam deposition (MSIBD) and (iv) filtered vacuum cathodic arc evaporation (VA) in the optimum energy range of about 100 eV were compared. Density data, Raman spectra and surface topography images show a different behaviour of the films. The different growth processes were discussed in connection with results from ion implantation experiments into IAE a-C and computer calculations of the ion-solid interactions by use of the TRIM-code. Self-interstitials in the sub-surface region of the carbon matrix created due to pure carbon ion beam bombardment (MSIBD and VA) are the key for the understanding of the densification process. The lower number of self-interstitials created during the noble-gas ion assisted processes can be compensated by extremely high argon-ion to carbon-neutral arrival ratios in the case of MS. Furthermore, the sputtered carbon atoms with energies in the range of a few eV should assist this deposition process. Without energetic carbon particles (thermal carbon atoms from the evaporation process) as in the case of neon ion assisted evaporation, it is also possible to prepare dense a-C, however with lower density (2.7 g/cm 3).

  10. The mechanism of galvanic/metal-assisted etching of silicon

    NASA Astrophysics Data System (ADS)

    Kolasinski, Kurt W.

    2014-08-01

    Metal-assisted etching is initiated by hole injection from an oxidant catalyzed by a metal nanoparticle or film on a Si surface. It is shown that the electronic structure of the metal/Si interface, i.e., band bending, is not conducive to diffusion of the injected hole away from the metal in the case of Ag or away from the metal/Si interface in the cases of Au, Pd, and Pt. Since holes do not diffuse away from the metals, the electric field resulting from charging of the metal after hole injection must instead be the cause of metal-assisted etching.

  11. Mechanical ventilation and thoracic artificial lung assistance during mechanical circulatory support with PUCA pump: in silico study.

    PubMed

    De Lazzari, Claudio; Genuini, Igino; Quatember, Bernhard; Fedele, Francesco

    2014-02-01

    Patients assisted with left ventricular assist device (LVAD) may require prolonged mechanical ventilatory assistance secondary to postoperative respiratory failure. The goal of this work is the study of the interdependent effects LVAD like pulsatile catheter (PUCA) pump and mechanical ventilatory support or thoracic artificial lung (TAL), by the hemodynamic point of view, using a numerical simulator of the human cardiovascular system. In the simulator, different circulatory sections are described using lumped parameter models. Lumped parameter models have been designed to describe the hydrodynamic behavior of both PUCA pump and thoracic artificial lung. Ventricular behavior atrial and septum functions were reproduced using variable elastance model. Starting from simulated pathological conditions we studied the effects produced on some hemodynamic variables by simultaneous PUCA pump, thoracic artificial lung or mechanical ventilation assistance. Thoracic artificial lung was applied in parallel or in hybrid mode. The effects of mechanical ventilation have been simulated by changing mean intrathoracic pressure value from -4 mmHg to +5 mmHg. The hemodynamic variables observed during the simulations, in different assisted conditions, were: left and right ventricular end systolic (diastolic) volume, systolic/diastolic aortic pressure, mean pulmonary arterial pressure, left and right mean atrial pressure, mean systemic venous pressure and the total blood flow. Results show that the application of PUCA (without mechanical ventilatory assistance) increases the total blood flow, reduces the left ventricular end systolic volume and increases the diastolic aortic pressure. Parallel TAL assistance increases the right ventricular end diastolic (systolic) volume reduction both when PUCA is switched "ON" and both when PUCA is switched "OFF". By switching "OFF" the PUCA pump, it seems that parallel thoracic artificial lung assistance produces a greater cardiac output (respect to

  12. Effects of equine assisted activities on autism spectrum disorder.

    PubMed

    Lanning, Beth A; Baier, Margaret E Matyastik; Ivey-Hatz, Julie; Krenek, Nancy; Tubbs, Jack D

    2014-08-01

    Quality of life assessments were used in this study to determine the behavioral changes of children diagnosed with autism spectrum disorder (ASD) who participated in equine assisted activities. Behavioral changes of children with ASD participating in 9 weeks of equines assisted activities (EAA) (N = 10) were compared to behavioral changes of children who participated in a non-equine intervention (N = 8). Parents noted significant improvements in their child's physical, emotional and social functioning following the first 6 weeks of EAA. The children participating in the non-equine program also demonstrated improvement in behavior, but to a lesser degree. The favorable outcome of this study lends support for continuation of programs utilizing EAA in the treatment of children with ASD. PMID:24526337

  13. Effects of equine assisted activities on autism spectrum disorder.

    PubMed

    Lanning, Beth A; Baier, Margaret E Matyastik; Ivey-Hatz, Julie; Krenek, Nancy; Tubbs, Jack D

    2014-08-01

    Quality of life assessments were used in this study to determine the behavioral changes of children diagnosed with autism spectrum disorder (ASD) who participated in equine assisted activities. Behavioral changes of children with ASD participating in 9 weeks of equines assisted activities (EAA) (N = 10) were compared to behavioral changes of children who participated in a non-equine intervention (N = 8). Parents noted significant improvements in their child's physical, emotional and social functioning following the first 6 weeks of EAA. The children participating in the non-equine program also demonstrated improvement in behavior, but to a lesser degree. The favorable outcome of this study lends support for continuation of programs utilizing EAA in the treatment of children with ASD.

  14. Carboxylate-assisted C(sp³)-H activation in olefin metathesis-relevant ruthenium complexes.

    PubMed

    Cannon, Jeffrey S; Zou, Lufeng; Liu, Peng; Lan, Yu; O'Leary, Daniel J; Houk, K N; Grubbs, Robert H

    2014-05-01

    The mechanism of C-H activation at metathesis-relevant ruthenium(II) benzylidene complexes was studied both experimentally and computationally. Synthesis of a ruthenium dicarboxylate at a low temperature allowed for direct observation of the C-H activation step, independent of the initial anionic ligand-exchange reactions. A first-order reaction supports an intramolecular concerted metalation-deprotonation mechanism with ΔG(‡)(298K) = 22.2 ± 0.1 kcal·mol(-1) for the parent N-adamantyl-N'-mesityl complex. An experimentally determined ΔS(‡) = -5.2 ± 2.6 eu supports a highly ordered transition state for carboxylate-assisted C(sp(3))-H activation. Experimental results, including measurement of a large primary kinetic isotope effect (k(H)/k(D) = 8.1 ± 1.7), agree closely with a computed six-membered carboxylate-assisted C-H activation mechanism where the deprotonating carboxylate adopts a pseudo-apical geometry, displacing the aryl ether chelate. The rate of cyclometalation was found to be influenced by both the electronics of the assisting carboxylate and the ruthenium ligand environment. PMID:24731019

  15. Carboxylate-assisted C(sp³)-H activation in olefin metathesis-relevant ruthenium complexes.

    PubMed

    Cannon, Jeffrey S; Zou, Lufeng; Liu, Peng; Lan, Yu; O'Leary, Daniel J; Houk, K N; Grubbs, Robert H

    2014-05-01

    The mechanism of C-H activation at metathesis-relevant ruthenium(II) benzylidene complexes was studied both experimentally and computationally. Synthesis of a ruthenium dicarboxylate at a low temperature allowed for direct observation of the C-H activation step, independent of the initial anionic ligand-exchange reactions. A first-order reaction supports an intramolecular concerted metalation-deprotonation mechanism with ΔG(‡)(298K) = 22.2 ± 0.1 kcal·mol(-1) for the parent N-adamantyl-N'-mesityl complex. An experimentally determined ΔS(‡) = -5.2 ± 2.6 eu supports a highly ordered transition state for carboxylate-assisted C(sp(3))-H activation. Experimental results, including measurement of a large primary kinetic isotope effect (k(H)/k(D) = 8.1 ± 1.7), agree closely with a computed six-membered carboxylate-assisted C-H activation mechanism where the deprotonating carboxylate adopts a pseudo-apical geometry, displacing the aryl ether chelate. The rate of cyclometalation was found to be influenced by both the electronics of the assisting carboxylate and the ruthenium ligand environment.

  16. Performance comparisons of naturally and mechanically ventilated solar-assisted nurseries

    SciTech Connect

    Milanuk, M.; Bodman, G.R.; DeShazer, J.A.; Schulte, D.

    1983-12-01

    When combined with solar floor heating and careful management, naturally ventilated swine nurseries can result in energy savings and comparable pig responses to mechanically ventilated nurseries of the current design that were also solar assisted.

  17. A novel active heads-up display for driver assistance.

    PubMed

    Doshi, Anup; Cheng, Shinko Yuanhsien; Trivedi, Mohan Manubhai

    2009-02-01

    In this paper, we introduce a novel laser-based wide-area heads-up windshield display which is capable of actively interfacing with a human as part of a driver assistance system. The dynamic active display (DAD) is a unique prototype interface that presents safety-critical visual icons to the driver in a manner that minimizes the deviation of his or her gaze direction without adding to unnecessary visual clutter. As part of an automotive safety system, the DAD presents alerts in the field of view of the driver only if necessary, which is based upon the state and pose of the driver, vehicle, and environment. This paper examines the effectiveness of DAD through a comprehensive comparative experimental evaluation of a speed compliance driver assistance system, which is implemented on a vehicular test bed. Three different types of display protocols for assisting a driver to comply with speed limits are tested on actual roadways, and these are compared with a conventional dashboard display. Given the inclination, drivers who are given an overspeed warning alert reduced the time required to slow down to the speed limit by 38% (p < 0.01) as compared with the drivers not given the alert. Additionally, certain alerts decreased distraction levels by reducing the time spent looking away from the road by 63% (p < 0.01). Ultimately, these alerts demonstrate the utility and promise of the DAD system.

  18. Active cell mechanics: Measurement and theory.

    PubMed

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

    2015-11-01

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

  19. Activities report in fluid mechanics

    NASA Astrophysics Data System (ADS)

    1986-10-01

    The research conducted at the Lille Institute of Fluid Mechanics (IMFL) concerns four areas: flight mechanics, structural mechanics, aerodynamics and applied fluid mechanics. Within these four areas, these topics are discussed: characterization of the unsteady pressures on an airfoil in turbulence; adaptation of the Kalman-Rauch filtering-smoothing method to instrumented free spin tests; vulnerability of aircraft fuel tanks; water surface impact; influence of an oscillating spoiler on the surrounding aerodynamic field; gunfiring similarity theory and rules; flow around a cylinder at low Reynolds number by holographic velocimetry and laser Doppler velocimetry; compressible turbulent flow computation; and the wake of wind turbine towers are discussed.

  20. MemoPA: Intelligent Personal Assistant Agents with a Case Memory Mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Ke-Jia; Barthès, Jean-Paul

    A Personal Assistant (PA) agent is a software agent capable of helping people to handle tasks in their workplace. The paper proposes a memory mechanism for personal assistant agents in order to enhance agent intelligence while working with the user or with other agents. Inspired by a case memory model in the domain of Case-Based Reasoning (CBR), this paper endows PA agents with a case memory mechanism, which results in improved PA agents: MemoPAs. We present the memory mechanism of MemoPA in detail, and report a first implementation of the method. Finally, future work is outlined for improving the memory mechanism.

  1. Brillouin microspectroscopy of nanostructured biomaterials: photonics assisted tailoring mechanical properties

    NASA Astrophysics Data System (ADS)

    Meng, Zhaokai; Jaiswal, Manish K.; Chitrakar, Chandani; Thakur, Teena; Gaharwar, Akhilesh K.; Yakovlev, Vladislav V.

    2016-03-01

    Developing new biomaterials is essential for the next-generation of materials for bioenergy, bioelectronics, basic biology, medical diagnostics, cancer research, and regenerative medicine. Specifically, recent progress in nanotechnology has stimulated the development of multifunctional biomaterials for tissue engineering applications. The physical properties of nanocomposite biomaterials, including elasticity and viscosity, play key roles in controlling cell fate, which underlines therapeutic success. Conventional mechanical tests, including uniaxial compression and tension, dynamic mechanical analysis and shear rheology, require mechanical forces to be directly exerted onto the sample and therefore may not be suitable for in situ measurements or continuous monitoring of mechanical stiffness. In this study, we employ spontaneous Brillouin spectroscopy as a viscoelasticity-specific probing technique. We utilized a Brillouin spectrometer to characterize biomaterial's microscopic elasticity and correlated those with conventional mechanical tests (e.g., rheology).

  2. [Mechanical circulatory assist using a miniaturized Archimedes screw].

    PubMed

    von Segesser, L K; Bisang, B; Leskosek, B; Turina, M

    1991-01-01

    An axial flow blood pump (Archimedes screw) for intraarterial left ventricular assist was evaluated in comparison to standard roller pump left heart bypass (LHBP) in 13 bovine experiments (bodyweight 74 +/- 15 kg). Full systemic heparinization (ACT greater than 500 s) was used for LHBP in comparison to limited systemic heparinization (ACT greater than 180 s) for axial. A standard battery of blood samples was taken before and at regular intervals throughout perfusion: (table; see text) Transarterial access and relatively limited blood trauma appear to be the main advantages of the evaluated axial flow blood pump. However, the impossibility to assess the pump flow may be a major problem for the management of the failing left ventricle.

  3. Environment assisted degradation mechanisms in advanced light metals

    NASA Technical Reports Server (NTRS)

    Gangloff, R. P.; Stoner, G. E.; Swanson, R. E.

    1989-01-01

    A multifaceted research program on the performance of advanced light metallic alloys in aggressive aerospace environments, and associated environmental failure mechanisms was initiated. The general goal is to characterize alloy behavior quantitatively and to develop predictive mechanisms for environmental failure modes. Successes in this regard will provide the basis for metallurgical optimization of alloy performance, for chemical control of aggressive environments, and for engineering life prediction with damage tolerance and long term reliability.

  4. Environment assisted degradation mechanisms in advanced light metals

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Stoner, Glenn E.; Swanson, Robert E.

    1988-01-01

    The general goals of the research program are to characterize alloy behavior quantitatively and to develop predictive mechanisms for environmental failure modes. Successes in this regard will provide the basis for metallurgical optimization of alloy performance, for chemical control of aggressive environments, and for engineering life prediction with damage tolerance and long term reliability.

  5. Plasma Assisted Combustion Mechanism for Hydrogen and Small Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey; Aleksandrov, Nikolay

    2015-09-01

    The main mechanisms of nonequilibrium gas excitation and their influence on the ignition and combustion were briefly discussed. Rotational excitation, vibrational excitation, electronic excitation, dissociation by electron impact and ionization were all analyzed, as well as the ways in which the selectivity of the gas excitation in the discharge can be controlled. The model consists of two parts. The first part describes gas excitation by electron impact - rotational, vibrational and electronic states population by pulsed discharges. The second part considers energy relaxation in the plasma (formation of Maxwell-Boltzmann equilibrium across translational, vibrational and electronic degrees of freedom of molecules), quenching and decomposition of excited states, their reactions and recombination - with formation of thermally-equilibrium pool of radicals, which could be considered as initial conditions for any detailed combustion kinetic mechanism. The mechanism was verified against available kinetic data in a wide temperature range. Despite of some lack of knowledge of mechanism details, nonequilibrium plasma demonstrates great potential for controlling ultra-lean, ultra-fast, low-temperature flames and is an extremely promising technology for a very wide range of applications.

  6. Ruptured subcapsular liver haematoma following mechanically-assisted cardiopulmonary resuscitation.

    PubMed

    Joseph, John R; Freundlich, Robert Edward; Abir, Mahshid

    2016-02-02

    A 64-year-old man with a history of ascending aortic surgery and pulmonary embolus presented with shortness of breath. He rapidly decompensated, prompting intubation, after which he lost pulses. Manual resuscitation was initiated immediately, with subsequent use of a LUCAS-2 mechanical compression device. The patient was given bolus thrombolytic therapy and regained pulses after 7 min of CPR. Compressions were reinitiated with the LUCAS-2 twice more during resuscitation over the subsequent hour for brief episodes of PEA. After confirmation of massive pulmonary embolism on CT, the patient underwent interventional radiology-guided ultrasonic catheter placement with local thrombolytic therapy and experienced immediate improvement in oxygenation. He later developed abdominal compartment syndrome, despite cessation of thrombolytic and anticoagulation therapy. Bedside exploratory abdominal laparotomy revealed a ruptured subcapsular haematoma of the liver. The patient's haemodynamics improved following surgery and he was extubated 11 days postarrest with intact neurological function.

  7. Mechanically assisted 3D ultrasound guided prostate biopsy system.

    PubMed

    Bax, Jeffrey; Cool, Derek; Gardi, Lori; Knight, Kerry; Smith, David; Montreuil, Jacques; Sherebrin, Shi; Romagnoli, Cesare; Fenster, Aaron

    2008-12-01

    There are currently limitations associated with the prostate biopsy procedure, which is the most commonly used method for a definitive diagnosis of prostate cancer. With the use of two-dimensional (2D) transrectal ultrasound (TRUS) for needle-guidance in this procedure, the physician has restricted anatomical reference points for guiding the needle to target sites. Further, any motion of the physician's hand during the procedure may cause the prostate to move or deform to a prohibitive extent. These variations make it difficult to establish a consistent reference frame for guiding a needle. We have developed a 3D navigation system for prostate biopsy, which addresses these shortcomings. This system is composed of a 3D US imaging subsystem and a passive mechanical arm to minimize prostate motion. To validate our prototype, a series of experiments were performed on prostate phantoms. The 3D scan of the string phantom produced minimal geometric distortions, and the geometric error of the 3D imaging subsystem was 0.37 mm. The accuracy of 3D prostate segmentation was determined by comparing the known volume in a certified phantom to a reconstructed volume generated by our system and was shown to estimate the volume with less then 5% error. Biopsy needle guidance accuracy tests in agar prostate phantoms showed that the mean error was 2.1 mm and the 3D location of the biopsy core was recorded with a mean error of 1.8 mm. In this paper, we describe the mechanical design and validation of the prototype system using an in vitro prostate phantom. Preliminary results from an ongoing clinical trial show that prostate motion is small with an in-plane displacement of less than 1 mm during the biopsy procedure.

  8. Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

    PubMed

    Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

    2016-11-15

    The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability. PMID:27450342

  9. Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

    PubMed

    Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

    2016-11-15

    The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability.

  10. External work output and force generation during synchronized intermittent mechanical ventilation. Effect of machine assistance on breathing effort.

    PubMed

    Marini, J J; Smith, T C; Lamb, V J

    1988-11-01

    We measured the mechanical work performed by 12 acutely ill patients during synchronized intermittent mandatory ventilation to determine the influence of volume-cycled machine assistance on inspiratory timing, respiratory muscle force development, and external work output. The frequency and tidal volume of spontaneous breaths increased at lower levels of mechanical ventilation, but inspiratory time fraction did not vary across the spectrum of machine support. As machine support was withdrawn, inspiratory work and pressure-time product increased progressively for both spontaneous and assisted breathing cycles. On a per cycle basis, work output was greater for assisted than for spontaneous breaths at all levels of comparison. Although the mean pressure developed by the patient during assisted cycles averaged approximately equal to 20% less than during adjacent unassisted cycles, contraction time averaged approximately equal to 20% longer, so that the pressure-time products were nearly equivalent for both types of cycle. Two indices of force reserve indicated that our patients taxed their maximal ventilatory capability at all but the highest levels of support. We conclude that under the conditions of this study the ventilatory pump continued to be active at all levels of machine assistance. Although work per liter related linearly to the proportion of minute ventilation borne by the patient, force generation differed little for spontaneous and machine-aided breaths at any specified level of support. Whether judged on the basis of mean developed pressure (work per liter of ventilation) or pressure-time product, little effort adaptation to volume-cycled machine assistance appears to occur on a breath-by-breath basis.

  11. Animal-assisted activity: experiences of institutionalized Japanese older adults.

    PubMed

    Kawamura, Namiko; Niiyama, Masayoshi; Niiyama, Harue

    2009-01-01

    The purpose of this study was to determine how a group of institutionalized elderly Japanese women perceived animal-assisted activity (AAA) and how their perceptions may be relevant to clinical nursing practices in the AAA context. The participants in this study, 8 elderly Japanese women residing in a nursing home in a northern Japanese city, had attended AAA sessions two times per month for 2 years prior to this study's data collection. Semi-structured interviews were conducted, and data were analyzed using phenomenological procedures. Six themes emerged concerning the interactive relationships between the participants and the animals; in addition, participants were able to develop interest in themselves, other residents, and their environment, due to feelings of ease and the development of one-on-one relationships with the AAA dogs. Volunteers from outside the nursing home made residents feel refreshed and gave them opportunities to broaden their contact with society. PMID:19227109

  12. Center-of-pressure movements during equine-assisted activities.

    PubMed

    Clayton, Hilary M; Kaiser, Leeann J; de Pue, Bonnie; Kaiser, Lana

    2011-01-01

    We compared anteroposterior and mediolateral range of motion and velocity of the center of pressure (COP) on the horse's back between riders without disabilities and riders with cerebral palsy. An electronic pressure mat was used to track COP movements beneath the saddle in 4 riders without disabilities and 4 riders with cerebral palsy. Comparisons between rider groups were made using the Mann-Whitney test (p < .05). The two rider groups differed significantly in anteroposterior range of COP motion, mediolateral range of COP motion, and mediolateral COP velocity. Anteroposterior COP velocity did not differ between groups. The results suggest that measurements of COP range of motion and velocity are potentially useful for monitoring changes in balance as an indicator of core stability during equine-assisted activities.

  13. Airway secretion clearance by mechanical exsufflation for post-poliomyelitis ventilator-assisted individuals.

    PubMed

    Bach, J R; Smith, W H; Michaels, J; Saporito, L; Alba, A S; Dayal, R; Pan, J

    1993-02-01

    Pulmonary complications from impaired airway secretion clearance mechanisms are major causes of morbidity and mortality for post-poliomyelitis individuals. The purpose of this study was to review the long-term use of manually assisted coughing and mechanical insufflation-exsufflation (MI-E) by post-poliomyelitis ventilator-assisted individuals (PVAIs) and to compare the peak cough expiratory flows (PCEF) created during unassisted and assisted coughing. Twenty-four PVAIs who have used noninvasive methods of ventilatory support for an average of 27 years, relied on methods of manually assisted coughing and/or MI-E without complications during intercurrent respiratory tract infections (RTIs). Nine of the 24 individuals were studied for PCEF. They had a mean forced vital capacity (FVC) of 0.54 +/- 0.47L and a mean maximum insufflation capacity achieved by air stacking of ventilator insufflations and glossopharyngeal breathing of 1.7L. The PCEF were as follows: unassisted, 1.78 +/- 1.16L/sec; following a maximum assisted insufflation, 3.75 +/- 0.73L/sec; with manual assistance by abdominal compression following a maximum assisted insufflation, 4.64 +/- 1.42L/sec; and with MI-E, 6.97 +/- 0.89L/sec. We conclude that manually assisted coughing and MI-E are effective and safe methods of airway secretion clearance for PVAIs with impaired expiratory muscle function who would otherwise be managed by endotracheal suctioning. Severely decreased maximum insufflation capacity but not vital capacity indicate need for a tracheostomy.

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

    PubMed

    Onoprienko, L V

    2011-01-01

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

  15. Web-Assisted Instruction for Changing Social Cognitive Variables Related to Physical Activity

    ERIC Educational Resources Information Center

    Suminski, Richard R.; Petosa, Rick

    2006-01-01

    The authors examined the efficacy of Web-assisted instruction for promoting the use of social cognitive theory (SCT) strategies related to physical activity. They recruited college students attending health courses. The authors created 3 groups (Web-assisted, comparison, and control) based on the course structure. The Web-assisted group received…

  16. 76 FR 60133 - Agency Information Collection (Application for Individualized Tutorial Assistance): Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ... AFFAIRS Agency Information Collection (Application for Individualized Tutorial Assistance): Activity Under... INFORMATION: Title: Application for Individualized Tutorial Assistance, VA Form 22-1990t. OMB Control Number... VA Form 22-1990t to apply for supplemental allowance for tutorial assistance. The student...

  17. Mechanism for the activation of glutamate receptors

    Cancer.gov

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

  18. Mechanical Design Technology--Modified. (Computer Assisted Drafting, Computer Aided Design). Curriculum Grant 84/85.

    ERIC Educational Resources Information Center

    Schoolcraft Coll., Livonia, MI.

    This document is a curriculum guide for a program in mechanical design technology (computer-assisted drafting and design developed at Schoolcraft College, Livonia, Michigan). The program helps students to acquire the skills of drafters and to interact with electronic equipment, with the option of becoming efficient in the computer-aided…

  19. CO assisted N2 functionalization activated by a dinuclear hafnium complex: a DFT mechanistic exploration.

    PubMed

    Ma, Xuelu; Zhang, Xin; Zhang, Wenchao; Lei, Ming

    2013-01-21

    In this paper, the reaction mechanisms of CO assisted N(2) cleavage and functionalization activated by a dinuclear hafnium complex are studied using a density function theory (DFT) method. Several key intermediates (Ia, Ib, Ic and Id) with axial/equatorial N=C=O coordination structures are found to be of importance along reaction pathways of CO assisted N(2) functionalization, which could provide a profound theoretical insight into the C-N bond formation and N-N bond cleavage. There are two different attack directions to insert the first CO molecule into the Hf-N bonds of the dinuclear hafnium complex, which lead to C-N bond formation. The calculated results imply that CO insertion into the Hf(1)-N(3) bond (Path A1) reacts more easily than that into the Hf(2)-N(3) bond (Path A3). But for the insertion of the second CO insertion to give 2A, there are two possibilities (Path A1 and Path A2) according to this insertion being after/before N-N bond cleavage. Two pathways (Path A1 and Path A2) are proved to be possible to form final dinitrogen functionalized products (oxamidide 2A, 2B and 2C) in this study, which explain the formation of different oxamidide isomers in CO assisted N(2) functionalization activated by a dinuclear hafnium complex.

  20. Program activities: DOE State and Local Assistance Programs, 1983 report

    SciTech Connect

    Not Available

    1983-10-01

    Progress achieved by the Department of Energy State and Local Assistance programs during FY 1983 and prior years is summarized. These programs provide financial and technical assistance to and through state and local governments, enabling them to plan and implement measures to improve the energy efficiency of industry, transportation, commercial establishments, public buildings and residences. The programs covered here are: State Energy Conservation, Energy Extension Service, Weatherization Assistance, Institutional Conservation, Energy-Related Inventions, Appropriate Technology Small Grants, and Grants Management and Technical Assistance. (MHR)

  1. Potential fluid mechanic pathways of platelet activation

    PubMed Central

    Shadden, Shawn C.; Hendabadi, Sahar

    2012-01-01

    Platelet activation is a precursor for blood clotting, which plays leading roles in many vascular complications and causes of death. Platelets can be activated by chemical or mechanical stimuli. Mechanically, platelet activation has been shown to be a function of elevated shear stress and exposure time. These contributions can be combined by considering the cumulative stress or strain on a platelet as it is transported. Here we develop a framework for computing a hemodynamic-based activation potential that is derived from a Lagrangian integral of strain rate magnitude. We demonstrate that such a measure is generally maximized along, and near to, distinguished material surfaces in the flow. The connections between activation potential and these structures are illustrated through stenotic flow computations. We uncover two distinct structures that may explain observed thrombus formation at the apex and downstream of stenoses. More broadly, these findings suggest fundamental relationships may exist between potential fluid mechanic pathways for mechanical platelet activation and the mechanisms governing their transport. PMID:22782543

  2. Design of Mechanism for Assisting Standing Movement Using Planar Linkage and Gear Train

    NASA Astrophysics Data System (ADS)

    Nango, Jun; Yoshizawa, Hisato; Liu, Jiajun

    The number of people who are in need of nursing care due to difficulties they experience with performing various activities of daily living is increasing. In particular, the action of standing up is performed frequently in daily life, and this action starts to induce pain in joints as people age. In this research, we develop a device whose seat plate follows the movement of the thigh in the action of standing up for the purpose of relieving the burden from the joints and reducing the effort associated with nursing care. The device is designed by using a planar five-link mechanism and a gear train, and only a single input is needed to drive the device. The respective lengths of the links are determined by comparing the movement of the seat plate of the device with the movement of the human thigh in the action of standing up. In addition, this device is expected to be useful for assisting users in standing up in a natural manner, including in the case when the body remains supported by the seat plate, as well as for guiding the individual movements of users in the action of standing up.

  3. Initial Work Toward A Robotically Assisted Extravehicular Activity Glove

    NASA Technical Reports Server (NTRS)

    Rogers, Jonathan M.; Peters, Benjamin J.; Laske, Evans A.; McBryan, Emily R.

    2016-01-01

    The Space Suit RoboGlove (SSRG) is a glove designed to provide additional grasp strength or endurance for an Extravehicular Activity (EVA) crew member, since a pressurized space suit gloved hand performance is a fraction of what the unencumbered human hand can achieve. There have been past efforts to improve space suit gloved hand performance by employing novel materials and construction techniques to the glove design, as well as integrating powered assistance devices into the gloves. These past efforts were not completely successful and the National Aeronautics and Space Administration (NASA) decided to develop a new glove based on the NASA/General Motors RoboGlove technology. The resulting SSRG used a unique approach to integrate the robotic actuators and sensors into a Phase VI EVA glove that resulted in a space suit glove that provided grasp augmentation to the user while the augmentation is activated, and also functioned as a normal glove when the augmentation is disabled. Care was taken to avoid adding excessive bulk to the glove or affecting tactility by choosing low-profile sensors and locating the actuators at a distance from the fingers. Conduits were used to guide robotic tendons from linear actuators, across the wrist, and to the fingers. The electromechanical design, softgoods integration, control system, and early test results of the first generation SSRG are presented in this paper. These early test results showed that this sensor integration did not impact tactile feedback in the glove and that the actuators provided potential for increased grip strength and reduction in grasp fatigue over time.

  4. The effect of animal-assisted activity on inpatients with schizophrenia.

    PubMed

    Chu, Cheng-I; Liu, Chao-Yin; Sun, Chi-Tzu; Lin, Jung

    2009-12-01

    The aim of this study was to evaluate the effects of animal-assisted activity on self-esteem, control over activities of daily living, and other psycho-physiological aspects among Taiwanese inpatients with schizophrenia. Thirty participants were randomly assigned to either the treatment or control group. A weekly animal-assisted activity program was arranged for patients in the treatment group for 2 months. A questionnaire assessing self-esteem, self-determination, social support, and psychiatric symptoms was completed the week before and the week after the animal-assisted activity. Compared with the control group, the treatment group showed significant improvement on all measures except for social support and negative psychiatric symptoms. The results of this study showed that animal-assisted activity can promote significant improvements in many clinical aspects among inpatients with schizophrenia. Therefore, animal-assisted activity should be integrated into the treatment of institutionalized patients with schizophrenia.

  5. Vortical flow characteristics of mechanical cavopulmonary assistance: Pre- and post-swirl dynamics.

    PubMed

    Throckmorton, Amy L; Chopski, Steven G; Birewar, Shravani N; Joa, Terence S; Huang, Pablo; Whitehead, Kevin K; Stevens, Randy M; Kresh, J Yasha

    2016-09-14

    Surgical optimization of the cavopulmonary connection and pharmacological therapy for dysfunctional Fontan physiology continue to advance, but these treatment approaches only slow the progression of decline to end-stage heart failure. The development of a mechanical cavopulmonary assist device will provide a viable therapeutic option in the bridging of patients to transplant or to stabilization. We hypothesize that rotational blood flow, delivered by an implantable axial flow blood pump, could effectively assist the venous circulation in Fontan patients by mimicking vortical blood flow patterns in the cardiovascular system. This study investigated seven new models of mechanical cavopulmonary assistance (single and dual-pump assist), created combinations of pump designs that deliver counter rotating vortical flow conditions, and analyzed pump performance, velocity streamlines, swirling strength, and energy augmentation in the cavopulmonary circuit for each support scenario. The model having an axial clockwise-oriented impeller in the inferior vena cava and an axial counterclockwise-oriented impeller rotating in the superior vena cava outperformed all of the support scenarios by enhancing the energy of the cavopulmonary circulation an average of 10.3% over the entire flow range and a maximum of 27.4% at %the higher flow rates. This research will guide the development of axial flow blood pumps for Fontan patients and demonstrated the high probability of %a cardiovascular benefit using counter rotating pumps in a dual support scenario, but found that this is dependent upon the patient-specific cavopulmonary anatomy. PMID:27061388

  6. 34 CFR 76.760 - More than one program may assist a single activity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false More than one program may assist a single activity. 76... States and Subgrantees § 76.760 More than one program may assist a single activity. A State or a subgrantee may use funds under more than one program to support different parts of the same project if...

  7. Kinetics and mechanism of the mercury(II)-assisted hydrolysis of methyl iodide.

    PubMed

    Celo, Valbona; Scott, Susannah L

    2005-04-01

    The kinetics and mechanism of the reaction of aqueous Hg(II) with methyl iodide have been investigated. The overall reaction is best described as Hg(II)-assisted hydrolysis, resulting in quantitative formation of methanol and, in the presence of excess methyl iodide, ultimately, HgI2 via the intermediate HgI+. The kinetics are biexponential when methyl iodide is in excess. At 25 degrees C, the acceleration provided by Hg2+ is 7.5 times greater than that caused by HgI+, while assistance of hydrolysis was not observed for HgI2. Thus, the reactions are not catalytic in Hg(II). The kinetics are consistent with an SN2-M+ mechanism involving electrophilic attack at iodide. As expected, methylation of mercury is not a reaction pathway; traces of methylmercury(II) are artifacts of the extraction/preconcentration procedure used for methylmercury analysis.

  8. Animal-Assisted Activity: Effects of a Complementary Intervention Program on Psychological and Physiological Variables.

    PubMed

    Nepps, Peggy; Stewart, Charles N; Bruckno, Stephen R

    2014-05-01

    Animal-assisted activity is the use of trained animals for the therapeutic, motivational, or educational benefit of patients. Subjects of this study were 218 patients hospitalized on the mental health unit of a community hospital with an existing, complementary animal-assisted activity program. Half of the patients participated in a 1-hour session of animal-assisted activity. The other half, who served as a comparison group, participated in a 1-hour stress management program. It was hypothesized that an animal-assisted activity program would improve ratings of depression, anxiety, and pain and the associated physiological measures of stress and discomfort. Self-report ratings of depression, anxiety, and pain were collected before and after treatment sessions, and blood pressure, pulse, and salivary cortisol were measured. There were significant decreases in depression (P < .0001), anxiety (P < .0001), pain (P < .0001), and pulse (P < .04) after animal-assisted activity program, comparable to those in the more traditional stress management group.

  9. Electrophilic assistance to the cleavage of an RNA model phopshodiester via specific and general base-catalyzed mechanisms.

    PubMed

    Corona-Martínez, David Octavio; Gomez-Tagle, Paola; Yatsimirsky, Anatoly K

    2012-10-19

    Kinetics of transesterification of the RNA model substrate 2-hydroxypropyl 4-nitrophenyl phosphate promoted by Mg(2+) and Ca(2+), the most common biological metals acting as cofactors for nuclease enzymes and ribozymes, as well as by Co(NH(3))(6)(3+), Co(en)(3)(3+), Li(+), and Na(+) cations, often employed as mechanistic probes, was studied in 80% v/v (50 mol %) aqueous DMSO, a medium that allows one to discriminate easily specific base (OH(-)-catalyzed) and general base (buffer-catalyzed) reaction paths. All cations assist the specific base reaction, but only Mg(2+) and Na(+) assist the general base reaction. For Mg(2+)-assisted reactions, the solvent deuterium isotope effects are 1.23 and 0.25 for general base and specific base mechanisms, respectively. Rate constants for Mg(2+)-assisted general base reactions measured with different bases fit the Brønsted correlation with a slope of 0.38, significantly lower than the slope for the unassisted general base reaction (0.77). Transition state binding constants for catalysts in the specific base reaction (K(‡)(OH)) both in aqueous DMSO and pure water correlate with their binding constants to 4-nitrophenyl phosphate dianion (K(NPP)) used as a minimalist transition state model. It was found that K(‡)(OH) ≈ K(NPP) for "protic" catalysts (Co(NH(3))(6)(3+), Co(en)(3)(3+), guanidinium), but K(‡)(OH) ≫ K(NPP) for Mg(2+) and Ca(2+) acting as Lewis acids. It appears from results of this study that Mg(2+) is unique in its ability to assist efficiently the general base-catalyzed transesterification often occurring in active sites of nuclease enzymes and ribozymes.

  10. Thermo-mechanical modeling of the electrically-assisted manufacturing (EAM) technique during open die forging

    NASA Astrophysics Data System (ADS)

    Salandro, Wesley A.

    This thesis contains all of the steps which allow the Electrically-Assisted Manufacturing (EAM) technique to be experimentally explored and analytically modeled for an electrically-assisted forging operation. Chapter 1 includes the problem statement, proposed solution, and literature reviews on EAM. Chapter 2 describes a thorough background on the EAM technique, highlights prior EAM research, and explains the research approach taken for this thesis. The coupled thermo-mechanical modeling strategy, along with the introduction of the Electroplastic Effect Coefficient (EEC) is provided in Chapter 3. Chapter 4 explains the two different approaches to determine the EEC profiles when modeling a particular metal. The simplified EAF mechanical model for electrically-assisted forging is presented in Chapter 5. Also in this chapter, the same modeling methodology (i.e. thermo-mechanical, EEC, etc.) is used to predict loads for an electrically-assisted bending (EAB) process. The following chapters explore how different material- and process-based parameters affect the EAF technique. Chapter 6 examines how different workpiece contact areas affect EAF effectiveness, along with an exploration of how well different metal forming lubricants perform with EAF. Chapter 7 explores if there is a difference in the thermal or mechanical profiles of specimens undergoing EAF forging tests with different average grain sizes. Chapter 8 examines the same effects as the previous chapter on specimens with varying levels of prior cold work. The materials- and process-based simplifications and sensitivities of the proposed modeling strategy are outlined in Chapter 9. Chapters 10-14 include the science behind the electroplastic effect, conclusions, future work, broader impacts, and intellectual merit, respectively. The overall intention of this thesis is to show the candidate's ability to take an idea for a new manufacturing process, prove that it works, and then understand and model the process

  11. Mechanics of light-activated network polymers

    NASA Astrophysics Data System (ADS)

    Long, Kevin Nicholas

    Mechanically responsive, environmentally activated polymers can undergo large, complex deformation in response to external stimuli such as thermal, luminous, and chemical changes to the environment. Light as a stimulus provides unique application potential because it allows for remote, rapid, and isothermal activation of the material with precise spatial control via existing optical technologies. While certain systems have received considerable attention, the state of the art of most light-activated polymers is limited to basic characterization and demonstrations. To make such materials available to the engineering and scientific communities, physically based theoretical and computational tools are required to guide experimental and design efforts that capitalize on their complex photo-mechanical couplings. The central objective of this thesis is to develop a multi-physics constitutive modeling framework to simulate the continuum scale, photo mechanical behavior of light-activated polymers and implement it into a finite element analysis setting. This framework is independent of specific underlying photo-stimulation mechanisms and is discussed in the context of photo-activated shape memory polymers and network rearranging polymers. Next, the framework is applied to the light-activated network rearranging polymer system, which is relaxed of stress upon irradiation with UV light, and a suite of characterization and application oriented experiments are carried out to calibrate and validate the model's predictive capabilities. The calibrated model is used to investigate several applications such as photo-activated stress relaxation of notched specimens, bending actuation, creep, the buckling of equi-biaxially deformed and irradiated films, and photomechanically formed 1D channels and ridges. Modeling creep involves additional complexity through simultaneous deformation and irradiation, and so the model framework is extended to cover such scenarios. Experiments, finite

  12. Schottky Barrier Catalysis Mechanism in Metal-Assisted Chemical Etching of Silicon.

    PubMed

    Lai, Ruby A; Hymel, Thomas M; Narasimhan, Vijay K; Cui, Yi

    2016-04-13

    Metal-assisted chemical etching (MACE) is a versatile anisotropic etch for silicon although its mechanism is not well understood. Here we propose that the Schottky junction formed between metal and silicon plays an essential role on the distribution of holes in silicon injected from hydrogen peroxide. The proposed mechanism can be used to explain the dependence of the etching kinetics on the doping level, doping type, crystallographic surface direction, and etchant solution composition. We used the doping dependence of the reaction to fabricate a novel etch stop for the reaction. PMID:27018712

  13. Molecular mechanisms regulating NLRP3 inflammasome activation

    PubMed Central

    Jo, Eun-Kyeong; Kim, Jin Kyung; Shin, Dong-Min; Sasakawa, Chihiro

    2016-01-01

    Inflammasomes are multi-protein signaling complexes that trigger the activation of inflammatory caspases and the maturation of interleukin-1β. Among various inflammasome complexes, the NLRP3 inflammasome is best characterized and has been linked with various human autoinflammatory and autoimmune diseases. Thus, the NLRP3 inflammasome may be a promising target for anti-inflammatory therapies. In this review, we summarize the current understanding of the mechanisms by which the NLRP3 inflammasome is activated in the cytosol. We also describe the binding partners of NLRP3 inflammasome complexes activating or inhibiting the inflammasome assembly. Our knowledge of the mechanisms regulating NLRP3 inflammasome signaling and how these influence inflammatory responses offers further insight into potential therapeutic strategies to treat inflammatory diseases associated with dysregulation of the NLRP3 inflammasome. PMID:26549800

  14. Distinct "assisted" and "spontaneous" mechanisms for the insertion of polytopic chlorophyll-binding proteins into the thylakoid membrane.

    PubMed

    Kim, S J; Jansson, S; Hoffman, N E; Robinson, C; Mant, A

    1999-02-19

    The biogenesis of several bacterial polytopic membrane proteins has been shown to require signal recognition particle (SRP) and protein transport machinery, and one such protein, the major light-harvesting chlorophyll-binding protein (LHCP) exhibits these requirements in chloroplasts. In this report we have used in vitro insertion assays to analyze four additional members of the chlorophyll-a/b-binding protein family. We show that two members, Lhca1 and Lhcb5, display an absolute requirement for stroma, nucleoside triphosphates, and protein transport apparatus, indicating an "assisted" pathway that probably resembles that of LHCP. Two other members, however, namely an early light-inducible protein 2 (Elip2) and photosystem II subunit S (PsbS), can insert efficiently in the complete absence of SRP, SecA activity, nucleoside triphosphates, or a functional Sec system. The data suggest a possibly spontaneous insertion mechanism that, to date, has been characterized only for simple single-span proteins. Of the membrane proteins whose insertion into thylakoids has been analyzed, five have now been shown to insert by a SRP/Sec-independent mechanism, suggesting that this is a mainstream form of targeting pathway. We also show that PsbS and Elip2 molecules are capable of following either "unassisted" or assisted pathways, and we discuss the implications for the mechanism and role of SRP in chloroplasts.

  15. Carboxylate-Assisted C(sp3)–H Activation in Olefin Metathesis-Relevant Ruthenium Complexes

    PubMed Central

    2015-01-01

    The mechanism of C–H activation at metathesis-relevant ruthenium(II) benzylidene complexes was studied both experimentally and computationally. Synthesis of a ruthenium dicarboxylate at a low temperature allowed for direct observation of the C–H activation step, independent of the initial anionic ligand-exchange reactions. A first-order reaction supports an intramolecular concerted metalation–deprotonation mechanism with ΔG⧧298K = 22.2 ± 0.1 kcal·mol–1 for the parent N-adamantyl-N′-mesityl complex. An experimentally determined ΔS⧧ = −5.2 ± 2.6 eu supports a highly ordered transition state for carboxylate-assisted C(sp3)–H activation. Experimental results, including measurement of a large primary kinetic isotope effect (kH/kD = 8.1 ± 1.7), agree closely with a computed six-membered carboxylate-assisted C–H activation mechanism where the deprotonating carboxylate adopts a pseudo-apical geometry, displacing the aryl ether chelate. The rate of cyclometalation was found to be influenced by both the electronics of the assisting carboxylate and the ruthenium ligand environment. PMID:24731019

  16. Mechanical circulatory assistance for the treatment of complications of coronary artery disease.

    PubMed

    Lamberti, J J; Anagnostopoulos, C E; Al-Sadir, J; Gupta, D S; Lin, C Y; Replogle, R L; Resnekov, L; Skinner, D B

    1976-02-01

    Surgery has become an accepted method of treatment for coronary artery disease and its complications. Revascularization results in significant improvement in symptoms for patients with angina pectoris. Occasionally, patients requiring surgery for angina pectoris will sustain reversible ischemic damage during operation; such patients can be successfully weaned from cardiopulmonary bypass with full recovery when intra-aortic balloon counterpulsation is used. Arrhythmias associated with ischemic damage to the myocardium also can be controlled when IABCP is used for physiologic assistance. Patients in cardiogenicshock of pulmonary edema after acute myocardial infarction have an ominous prognosis. When decompensation occurs, IABCP may be used to stabilize the patient and to allow study and corrective surgery if possible. The prognosis is better for patients with ventricular septal defect, although selected patients without a mechanical defect of the myocardium can be salvaged if the response to IABCP is favorable. Counterpulsation has also been shown to be useful in achieving pulsatile cardiopulmonary bypass and in assisting high-risk patients through operation. External pressure circulatory assist (EPCA) is less effective than IABCP in assisting the failing myocardium; however, the external device is noninvasive and may be a useful adjunct in situations where IABCP is not feasible.

  17. Program activities, DOE state and local assistance programs, 1980 report

    SciTech Connect

    Chiogioji, Melvin H.

    1981-01-01

    Progress achieved by DOE State and Local Assistance Programs during FY 1980 and since they were established is summarized. These programs enable improved energy efficiency of industry, transportation, commercial establishments, public buildings, and residences. Eight programs (State Energy Conservation, Energy Extension Service, Weatherization Assistance, Institutional Buildings Grants, Energy-Related Inventions, Appropriate Technology Small Grants, Emergency Energy Conservation, Emergency Building Temperature Restrictions) are described. They provide the impetus for thousands of individual and organizational actions that have significantly affected national energy use patterns. (MCW)

  18. Efficient Catalytic Activity BiFeO3 Nanoparticles Prepared by Novel Microwave-Assisted Synthesis.

    PubMed

    Zou, Jing; Gong, Wanyun; Ma, Jinai; Li, Lu; Jiang, Jizhou

    2015-02-01

    A novel microwave-assisted sol-gel method was applied to the synthesis of the single-phase perovskite bismuth ferrite nanoparticles (BFO NPs) with the mean diameter ca. 73.7 nm. The morphology was characterized by scanning electron microscope (SEM). The X-ray diffraction (XRD) revealed the rhombohedral phase with R3c space group. The weak ferromagnetic behavior at room temperature was affirmed by the vibrating sample magnetometer (VSM). According to the UV-vis diffuse reflectance spectrum (UV-DSR), the band gap energy of BFO NPs was determined to be 2.18 eV. The electrochemical activity was evaluated by BFO NPs-chitosan-glassy carbon electrode (BFO-CS-GCE) sensor for detection of p-nitrophenol contaminants. The material showed an efficient oxidation catalytic activity by degrading methylene blue (MB). It was found that the degradation efficiency of 10 mg L-1 MB at pH 6.0 was above 90.9% after ultrasound- and microwave-combined-assisted (US-MW) irradiation for 15 min with BFO NPs as catalyst and H202 as oxidant. A possible reaction mechanism of degradation of MB was also proposed.

  19. Efficient Catalytic Activity BiFeO3 Nanoparticles Prepared by Novel Microwave-Assisted Synthesis.

    PubMed

    Zou, Jing; Gong, Wanyun; Ma, Jinai; Li, Lu; Jiang, Jizhou

    2015-02-01

    A novel microwave-assisted sol-gel method was applied to the synthesis of the single-phase perovskite bismuth ferrite nanoparticles (BFO NPs) with the mean diameter ca. 73.7 nm. The morphology was characterized by scanning electron microscope (SEM). The X-ray diffraction (XRD) revealed the rhombohedral phase with R3c space group. The weak ferromagnetic behavior at room temperature was affirmed by the vibrating sample magnetometer (VSM). According to the UV-vis diffuse reflectance spectrum (UV-DSR), the band gap energy of BFO NPs was determined to be 2.18 eV. The electrochemical activity was evaluated by BFO NPs-chitosan-glassy carbon electrode (BFO-CS-GCE) sensor for detection of p-nitrophenol contaminants. The material showed an efficient oxidation catalytic activity by degrading methylene blue (MB). It was found that the degradation efficiency of 10 mg L-1 MB at pH 6.0 was above 90.9% after ultrasound- and microwave-combined-assisted (US-MW) irradiation for 15 min with BFO NPs as catalyst and H202 as oxidant. A possible reaction mechanism of degradation of MB was also proposed. PMID:26353647

  20. Comets: mechanisms of x-ray activity

    NASA Astrophysics Data System (ADS)

    Ibadov, Subhon

    2016-07-01

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

  1. Amino acid tautomerization reactions in aqueous solution via concerted and assisted mechanisms using free energy curves from MD simulation.

    PubMed

    Tolosa, Santiago; Hidalgo, Antonio; Sansón, Jorge A

    2012-11-01

    A theoretical study is described of chemical reactions in solution by means of molecular dynamics simulations, with solute-solvent interaction potentials derived from AMBER van der Waals parameters and QM/MM electrostatic charges in solution. The solvent is used as the reaction coordinate, and the free energy curves to calculate the properties related to the reaction mechanism. The proposed scheme is applied to the tautomerization process in aqueous solution for some amino acids H(2)NCHR-COOH (with R = H being glycine, R = CH(3) alanine, R = CH(2)OH serine, and R = CH(2)COOH aspartic acid), focusing on the role of the solvent in the reaction (assisted versus unassisted mechanisms) and on the effect of the hydrophilic/hydrophobic character of the radical R on the activation and reaction energies.

  2. 75 FR 33636 - Bureau of Justice Assistance; Agency Information Collection Activities: Proposed Collection...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Office of Justice Programs Bureau of Justice Assistance; Agency Information Collection Activities: Proposed Collection Comments Requested ACTION: 30-Day Notice of Information Collection Under Review: New Collection Bureau of Justice Assistance...

  3. 24 CFR 1003.209 - Prohibition on use of assistance for employment relocation activities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Prohibition on use of assistance for employment relocation activities. 1003.209 Section 1003.209 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND...

  4. Curriculum Development of Learning Activity Packets, Dental Assisting Program. Final Report.

    ERIC Educational Resources Information Center

    Hempler, Nancy A.

    A dental assisting instructor was provided with 250 hours of released time to develop standardized Learning Activity Packets (LAPs) for the Dental Assisting program at the Bellingham (Washington) Vocational Technical Institute. The instructor reviewed unit objectives, gathered input from local dental professionals, reviewed reference materials,…

  5. Topological mechanics: from metamaterials to active matter

    NASA Astrophysics Data System (ADS)

    Vitelli, Vincenzo

    2015-03-01

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

  6. Mechanically activated artificial cell by using microfluidics

    PubMed Central

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

    2016-01-01

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

  7. Mechanically activated artificial cell by using microfluidics.

    PubMed

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

    2016-01-01

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

  8. Mechanically activated artificial cell by using microfluidics.

    PubMed

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

    2016-01-01

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

  9. Improvement of mechanical properties by additive assisted laser sintering of PEEK

    SciTech Connect

    Kroh, M. Bonten, C.; Eyerer, P.

    2014-05-15

    The additive assisted laser sintering was recently developed at IKT: A carbon black (CB) additive is used to adjust the polymer's laser absorption behavior with the aim to improve the interconnection of sintered powder layers. In this paper a parameter study, Polyetheretherketone (PEEK) samples were prepared with different contents of carbon black and were laser sintered with varying thermal treatment. The samples were mechanically tested and investigated by optical light and transmission electron microscopy. An influence on the morphology at the border areas of particles and intersections of laser sintered layers was found. Depending on the viscosity of the raw material and CB content, different shapes of lamellae were observed. These (trans-) crystalline or polymorph structures, respectively, influence the thermal and mechanical behavior of the virgin PEEK. Moreover, the thermal treatment during the sintering process caused an improvement of mechanical properties like tensile strength and elongation at break.

  10. Improvement of mechanical properties by additive assisted laser sintering of PEEK

    NASA Astrophysics Data System (ADS)

    Kroh, M.; Bonten, C.; Eyerer, P.

    2014-05-01

    The additive assisted laser sintering was recently developed at IKT: A carbon black (CB) additive is used to adjust the polymer's laser absorption behavior with the aim to improve the interconnection of sintered powder layers. In this paper a parameter study, Polyetheretherketone (PEEK) samples were prepared with different contents of carbon black and were laser sintered with varying thermal treatment. The samples were mechanically tested and investigated by optical light and transmission electron microscopy. An influence on the morphology at the border areas of particles and intersections of laser sintered layers was found. Depending on the viscosity of the raw material and CB content, different shapes of lamellae were observed. These (trans-) crystalline or polymorph structures, respectively, influence the thermal and mechanical behavior of the virgin PEEK. Moreover, the thermal treatment during the sintering process caused an improvement of mechanical properties like tensile strength and elongation at break.

  11. Theoretical study of the neutral hydrolysis of hydrogen isocyanate in aqueous solution via assisted-concerted mechanisms.

    PubMed

    Tolosa Arroyo, S; Hidalgo Garcia, A; Sansón Martín, J A

    2009-03-01

    A procedure is described for the theoretical study of chemical reactions in solution by means of molecular dynamics simulation, with solute-solvent interaction potentials derived from ab initio quantum calculations. We apply the procedure to the case of neutral hydrogen isocyanate hydrolysis, HNCO + 2 H(2)O --> H(2)NCOOH + H(2)O, in aqueous solution, via the assisted-concerted mechanisms and the two-water model. We used the solvent as a reaction coordinate and the free-energy curves for the calculation of the properties related to the reaction mechanisms, with a particular focus on the reaction and activation energies. The results showed that the mechanism with two water molecules attacking the C=N bond is preferred to the mechanism with three waters forming a ring of eight members. In addition, the aqueous medium significantly reduces the activation barrier (DeltaG(double dagger) = 13.9 kcal/mol) and makes the process more exothermic (DeltaG = -11.1 kcal/mol) relative to the gas-phase reaction, increasing the rate constant of the process to k = 4.25 x 10(5) s(-1). PMID:19209882

  12. Amino acids assisted hydrothermal synthesis of hierarchically structured ZnO with enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Guo, Yanxia; Lin, Siwen; Li, Xuan; Liu, Yuping

    2016-10-01

    Novel hierarchically structured ZnO, including rose-like, dandelion-like and flower-like, have been synthesized through a simple hydrothermal process using different amino acids (glutamine, histidine and glycine) as structure-directing agents and urea as deposition agent, followed by subsequent calcination. Amino acids played a crucial role in the formation of hierarchically structured ZnO, and different amino acids could induce different exquisite shapes and assembly ways, as well as more oxygen defects. The prepared hierarchically structured ZnO exhibited excellent photocatalytic activities for the photodegradation of Rhodamine B, which was associated with their special hierarchical structures, large BET surface area and the existence of more oxygen defects. Amino acid-assisted growth mechanism of hierarchically structured ZnO was also discussed.

  13. Ethanol assisted synthesis of anatase nanobelts with improved crystallinity and photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ni, Binbin; Li, Feng; Li, Xiaoning; Fu, Zhengping; Zhu, Yanwu; Lu, Yalin

    2013-10-01

    A modified alkaline hydrothermal method via adding the ethanol treatment to the intermediates was developed to synthesize TiO2 nanobelts, in which the main phase is anatase. Compared with the previous reported TiO2 nanobelts obtained without the ethanol treatment, the new TiO2 nanobelts obtained through the ethanol assisted route are with much improved anatase crystallinity and a sharply reduced amount of TiO2-B phase, as well as a significantly higher photocatalytic activity that is even better than P25 for degrading Rhodamine-B under the ultraviolet light irradiation, which apparently correlates to the increased contents and crystallinity of anatase. The mechanism of ethanol treatment is also discussed based on the FTIR results.

  14. An enzyme-assisted nanoparticle crosslinking approach to enhance the mechanical strength of peptide-based supramolecular hydrogels.

    PubMed

    Li, Ying; Ding, Yin; Qin, Meng; Cao, Yi; Wang, Wei

    2013-10-01

    In this work we reported an enzyme-assisted nanoparticle crosslinking (EANC) strategy to enhance the mechanical stability of peptide-based supramolecular hydrogels by more than 3000 times. PMID:23948779

  15. Dormancy activation mechanism of tracheal stem cells

    PubMed Central

    Li, Xin; Xu, Jing-xian; Jia, Xin-Shan; Li, Wen-ya; Han, Yi-chen; Wang, En-hua; Li, Fang

    2016-01-01

    Accurate markers and molecular mechanisms of stem cell dormancy and activation are poorly understood. In this study, the anti-cancer drug, 5-fluorouracil, was used to selectively kill proliferating cells of human bronchial epithelial (HBE) cell line. This method can enrich and purify stem cell population. The dormant versus active status of stem cells was determined by phosphorylation of RNAp II Ser2. The surviving stem cells were cultured to form stem cell spheres expressing stem cell markers and transplanted into nude mice to form a teratoma. The results demonstrated the properties of stem cells and potential for multi-directional differentiation. Bisulfite sequencing polymerase chain reaction showed that demethylation of the Sox2 promoter by 5-FU resulted in Sox2 expression in the dormant stem cells. This study shows that the dormancy and activation of HBE stem cells is closely related to epigenetic modification. PMID:27009861

  16. Mechanism of FGF receptor dimerization and activation

    PubMed Central

    Sarabipour, Sarvenaz; Hristova, Kalina

    2016-01-01

    Fibroblast growth factors (fgfs) are widely believed to activate their receptors by mediating receptor dimerization. Here we show, however, that the FGF receptors form dimers in the absence of ligand, and that these unliganded dimers are phosphorylated. We further show that ligand binding triggers structural changes in the FGFR dimers, which increase FGFR phosphorylation. The observed effects due to the ligands fgf1 and fgf2 are very different. The fgf2-bound dimer structure ensures the smallest separation between the transmembrane (TM) domains and the highest possible phosphorylation, a conclusion that is supported by a strong correlation between TM helix separation in the dimer and kinase phosphorylation. The pathogenic A391E mutation in FGFR3 TM domain emulates the action of fgf2, trapping the FGFR3 dimer in its most active state. This study establishes the existence of multiple active ligand-bound states, and uncovers a novel molecular mechanism through which FGFR-linked pathologies can arise. PMID:26725515

  17. A Novel Transcription Mechanism Activated by Ethanol

    PubMed Central

    Lin, Xinghua; Yang, Hong; Zhang, Hongfeng; Zhou, LiChun; Guo, ZhongMao

    2013-01-01

    Solute carrier family 7, member 11 (Slc7a11) is a plasma membrane cystine/glutamate exchanger that provides intracellular cystine to produce glutathione, a major cellular antioxidant. Oxidative and endoplasmic reticulum stresses up-regulate Slc7a11 expression by activation of nuclear factor erythroid 2-related factor 2 and transcription factor 4. This study examined the effect of ethanol on Slc7a11 expression and the underlying mechanism involved. Treatment of mouse hepatic stellate cells with ethanol significantly increased Slc7a11 mRNA and protein levels. Deletion of a 20-bp DNA sequence between −2044 to −2024 upstream of the transcription start site significantly increased basal activity and completely abolished the ethanol-induced activity of the Slc7a11 promoter. This deletion did not affect Slc7a11 promoter activity induced by oxidative or endoplasmic reticulum stress. DNA sequence analysis revealed a binding motif for octamer-binding transcription factor 1 (OCT-1) in the deleted fragment. Mutation of this OCT-1 binding motif resulted in a similar effect as the deletion experiment, i.e. it increased the basal promoter activity and abolished the response to ethanol. Ethanol exposure significantly inhibited OCT-1 binding to the Slc7a11 promoter region, although it did not alter OCT-1 mRNA and protein levels. OCT-1 reportedly functions as either a transcriptional enhancer or repressor, depending on the target genes. Results from this study suggest that OCT-1 functions as a repressor on the Slc7a11 promoter and that ethanol inhibits OCT-1 binding to the Slc7a11 promoter, thereby increasing Slc7a11 expression. Taken together, inhibition of the DNA binding activity of transcriptional repressor OCT-1 is a mechanism by which ethanol up-regulates Slc711 expression. PMID:23592778

  18. Percutaneous mechanical assist for severe cardiogenic shock due to acute right ventricular failure.

    PubMed

    Kipp, Ryan; Raval, Amish N

    2015-05-01

    Acute right ventricular failure can lead to severe cardiogenic shock and death. Recovery may be achieved with early supportive measures. In many patients, intravenous fluid and inotropic resuscitation is inadequate to improve cardiac output. In these cases, percutaneous mechanical assist may provide a non-surgical bridge to recovery. Herein, we describe a case series of patients with severe, refractory cardiogenic shock due to acute right ventricular failure who received a continuous flow percutaneous ventricular device primarily utilizing the right internal jugular vein for out flow cannula placement.

  19. 78 FR 54457 - Agency Information Collection Activities; Comment Request; Student Assistance General Provisions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-04

    ... Agency Information Collection Activities; Comment Request; Student Assistance General Provisions--Satisfactory Academic Progress Policy AGENCY: Federal Student Aid (FSA), Department of Education (ED). ACTION....), ED is proposing an extension of an existing information collection. DATES: Interested persons...

  20. Mechanical Modulation of Phonon-Assisted Field Emission in a Silicon Nanomembrane Detector for Time-of-Flight Mass Spectrometry

    PubMed Central

    Park, Jonghoo; Blick, Robert H.

    2016-01-01

    We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice temperature in the silicon nanomembrane, resulting from the transduction of ion kinetic energy into thermal energy through the ion bombardment, induces not only phonon-assisted field emission but also a mechanical vibration in the silicon nanomembrane. The coupling of these mechanical and electrical phenomenon leads to mechanical modulation of phonon-assisted field emission. The thermal energy relaxation through mechanical vibration in addition to the lateral heat conduction and field emission in the silicon nanomembrane offers effective cooling of the nanomembrane, thereby allowing high resolution mass analysis. PMID:26861329

  1. Mechanical Modulation of Phonon-Assisted Field Emission in a Silicon Nanomembrane Detector for Time-of-Flight Mass Spectrometry.

    PubMed

    Park, Jonghoo; Blick, Robert H

    2016-01-01

    We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice temperature in the silicon nanomembrane, resulting from the transduction of ion kinetic energy into thermal energy through the ion bombardment, induces not only phonon-assisted field emission but also a mechanical vibration in the silicon nanomembrane. The coupling of these mechanical and electrical phenomenon leads to mechanical modulation of phonon-assisted field emission. The thermal energy relaxation through mechanical vibration in addition to the lateral heat conduction and field emission in the silicon nanomembrane offers effective cooling of the nanomembrane, thereby allowing high resolution mass analysis. PMID:26861329

  2. Relationships between muscle activity and autonomic regulation during cycling with a torque-assisted bicycle.

    PubMed

    Kiryu, Tohru; Yamagata, Jun

    2006-01-01

    For customizing the assistance scheme of a torque-assisted bicycle, we estimated physical activity during cycling with ECG and surface EMG for the circuit including a steep uphill section near the middle and compared it with the vehicle data. Using the respiratory-sinus-arrhythmia-related power ratio in the fluctuation of the R-R interval, prRSA and a muscular fatigue index, we classified physical activity into four groups for each trial. Results showed that the assist enlarged prRSA but did not sufficiently support muscular fatigue.

  3. Mechanical insufflation-exsufflation. Comparison of peak expiratory flows with manually assisted and unassisted coughing techniques.

    PubMed

    Bach, J R

    1993-11-01

    Pulmonary complications are major causes of morbidity and mortality for patients with severe expiratory muscle weakness. The purpose of this study was to compare peak cough expiratory flows (PCEFs) during unassisted and assisted coughing and review the long-term use of mechanical insufflation-exsufflation (MI-E) for 46 neuromuscular ventilator users. These individuals used noninvasive methods of ventilatory support for a mean of 21.1 h/d for 17.3 +/- 15.5 years. They relied on manually assisted coughing and/or MI-E during periods of productive airway secretion. They reported a mean of 0.7 +/- 1.2 cases of pneumonia and other serious pulmonary complications and 2.8 +/- 5.6 hospitalizations during the 16.4-year period and no complications of MI-E. A sample of 21 of these patients with a mean forced vital capacity of 490 +/- 370 ml had a mean maximum insufflation capacity (MIC) achieved by a combination of air stacking of ventilator insufflations and glossopharyngeal breathing of 1,670 +/- 540 ml. The PCEFs for this sample were: following an unassisted inspiration, 1.81 +/- 1.03 L/s; following a MIC maneuver, 3.37 +/- 1.07 L/s; with manual assistance by abdominal compression following a MIC maneuver, 4.27 +/- 1.29 L/s; and with MI-E, 7.47 +/- 1.02 L/s. Each PCEF was significantly greater than the preceding, respectively (p < 0.01). We conclude that manually assisted coughing and MI-E are effective and safe methods for facilitating airway secretion clearance for neuromuscular ventilator users who would otherwise be managed by endotracheal suctioning. Severely decreased MIC, but not necessarily vital capacity, is an indication for tracheostomy.

  4. Activities of the Institute for Mechanical Engineering

    NASA Astrophysics Data System (ADS)

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

  5. Active ageing: independence through technology assisted health optimisation.

    PubMed

    Manning, B R M; McCann, J; Benton, S; Bougourd, J

    2008-01-01

    The potential doubling in the percentage of the elderly within the populations of Europe and beyond over the next decades has focused informatics research on the development Assistive Technologies and Smart Homes. However its concentration on creating a supportive home environment also has the potential for makings its users over dependent on its facilities and as a result trapped within it. This paper outlines an approach that extends the smart homes concept out into the wider community to create a smart environment that not only maintains contact with all their home-based services, but also expands these to include other facilities needed to assist them whilst on the move. This involves the convergence of physiological monitoring, communications and computing with leading-edge textile technologies, which uses a multi-layered, multi-functional clothing system as a mobile and extended variant of a smart home IP hub. In addition to variable functionality capabilities of the clothing layers in terms of thermal, shock-absorbent and other characteristics, wireless IP connectivity is provided between layers with external links typically being WiFi enabled. Health optimisation is provided by on-going lifestyle guidance/action feedback based on auto-diagnostic analysis. PMID:18560086

  6. Mechanisms of infrared-laser-assisted atomic ionization by attosecond pulses

    SciTech Connect

    Tong, X. M.; Ranitovic, P.; Cocke, C. L.; Toshima, N.

    2010-02-15

    We propose a mechanism to understand the infrared (IR) laser assisted atomic ionization by attosecond pulses (AP). Atomic structures in an IR laser field are described by Floquet states and atoms can be ionized to a Floquet state by a single AP through different Floquet components. The interference of ionization through different Floquet components results in the oscillation of the ionization yield as a function of the arriving time of the AP. The proposed mechanism explains the recent experimental observations [Johnsson et al., Phys. Rev. Lett. 99, 233001 (2007)]. Furthermore, we find that, for a specified photoelectron energy, the ionization yield always oscillates as a function of the relative phase between the AP and the IR laser for both He and Ar atoms.

  7. Mechanism for accurate, protein-assisted DNA annealing by Deinococcus radiodurans DdrB.

    PubMed

    Sugiman-Marangos, Seiji N; Weiss, Yoni M; Junop, Murray S

    2016-04-19

    Accurate pairing of DNA strands is essential for repair of DNA double-strand breaks (DSBs). How cells achieve accurate annealing when large regions of single-strand DNA are unpaired has remained unclear despite many efforts focused on understanding proteins, which mediate this process. Here we report the crystal structure of a single-strand annealing protein [DdrB (DNA damage response B)] in complex with a partially annealed DNA intermediate to 2.2 Å. This structure and supporting biochemical data reveal a mechanism for accurate annealing involving DdrB-mediated proofreading of strand complementarity. DdrB promotes high-fidelity annealing by constraining specific bases from unauthorized association and only releases annealed duplex when bound strands are fully complementary. To our knowledge, this mechanism provides the first understanding for how cells achieve accurate, protein-assisted strand annealing under biological conditions that would otherwise favor misannealing.

  8. Mechanism and active variety of allelochemicals

    USGS Publications Warehouse

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

    2004-01-01

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

  9. Exoskeleton control for lower-extremity assistance based on adaptive frequency oscillators: adaptation of muscle activation and movement frequency.

    PubMed

    Aguirre-Ollinger, Gabriel

    2015-01-01

    In this article, we analyze a novel strategy for assisting the lower extremities based on adaptive frequency oscillators. Our aim is to use the control algorithm presented here as a building block for the control of powered lower-limb exoskeletons. The algorithm assists cyclic movements of the human extremities by synchronizing actuator torques with the estimated net torque exerted by the muscles. Synchronization is produced by a nonlinear dynamical system combining an adaptive frequency oscillator with a form of adaptive Fourier analysis. The system extracts, in real time, the fundamental frequency component of the net muscle torque acting on a specific joint. Said component, nearly sinusoidal in shape, is the basis for the assistive torque waveform delivered by the exoskeleton. The action of the exoskeleton can be interpreted as a virtual reduction in the mechanical impedance of the leg. We studied the ability of human subjects to adapt their muscle activation to the assistive torque. Ten subjects swung their extended leg while coupled to a stationary hip joint exoskeleton. The experiment yielded a significant decrease, with respect to unassisted movement, of the activation levels of an agonist/antagonist pair of muscles controlling the hip joint's motion, which suggests the exoskeleton control has potential for assisting human gait. A moderate increase in swing frequency was observed as well. We theorize that the increase in frequency can be explained by the impedance model of the assisted leg. Per this model, subjects adjust their swing frequency in order to control the amount of reduction in net muscle torque.

  10. Exoskeleton control for lower-extremity assistance based on adaptive frequency oscillators: adaptation of muscle activation and movement frequency.

    PubMed

    Aguirre-Ollinger, Gabriel

    2015-01-01

    In this article, we analyze a novel strategy for assisting the lower extremities based on adaptive frequency oscillators. Our aim is to use the control algorithm presented here as a building block for the control of powered lower-limb exoskeletons. The algorithm assists cyclic movements of the human extremities by synchronizing actuator torques with the estimated net torque exerted by the muscles. Synchronization is produced by a nonlinear dynamical system combining an adaptive frequency oscillator with a form of adaptive Fourier analysis. The system extracts, in real time, the fundamental frequency component of the net muscle torque acting on a specific joint. Said component, nearly sinusoidal in shape, is the basis for the assistive torque waveform delivered by the exoskeleton. The action of the exoskeleton can be interpreted as a virtual reduction in the mechanical impedance of the leg. We studied the ability of human subjects to adapt their muscle activation to the assistive torque. Ten subjects swung their extended leg while coupled to a stationary hip joint exoskeleton. The experiment yielded a significant decrease, with respect to unassisted movement, of the activation levels of an agonist/antagonist pair of muscles controlling the hip joint's motion, which suggests the exoskeleton control has potential for assisting human gait. A moderate increase in swing frequency was observed as well. We theorize that the increase in frequency can be explained by the impedance model of the assisted leg. Per this model, subjects adjust their swing frequency in order to control the amount of reduction in net muscle torque. PMID:25655955

  11. Outcomes of patients implanted with a left ventricular assist device at nontransplant mechanical circulatory support centers.

    PubMed

    Katz, Marc R; Dickinson, Michael G; Raval, Nirav Y; Slater, James P; Dean, David A; Zeevi, Gary R; Horn, Evelyn M; Salemi, Arash

    2015-05-01

    The goal of this study was to assess outcomes of patients who underwent implantation of left ventricular assist devices (LVADs) at nontransplantation mechanical circulatory support centers. As the availability of LVADs for advanced heart failure has expanded to nontransplantation mechanical circulatory support centers, concerns have been expressed about maintaining good outcomes. Demographics and outcomes were evaluated in 276 patients with advanced heart failure who underwent implantation of LVADs as bridge to transplantation or destination therapy at 27 open-heart centers. Baseline characteristics, operative mortality, length of stay, readmission rate, adverse events, quality of life, and survival were analyzed. The overall 30-day mortality was 3% (8 of 276), and survival rates at 6, 12, and 24 months, respectively, were 92±2%, 88±3%, and 84±4% for the bridge-to-transplantation group and 81±3%, 70±5%, and 63±6% for the destination therapy group, comparable with results published by the national Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). The median length of stay for all patients was 21 days. Bleeding was the most frequent adverse event. Stroke occurred in 4% (bridge to transplantation) and 6% (destination therapy) of patients. Quality-of-life measures and 6-minute walk distances showed sustained improvements throughout support. In conclusion, outcomes with LVAD support at open-heart centers are acceptable and comparable with results from the INTERMACS registry. With appropriate teams, training, center commitment, and certification, LVAD therapy is being disseminated in a responsible way to open-heart centers. PMID:25772738

  12. Ultrasound-assisted butyl acetate synthesis catalyzed by Novozym 435: enhanced activity and operational stability.

    PubMed

    Martins, Andréa B; Schein, Mirela F; Friedrich, John L R; Fernandez-Lafuente, Roberto; Ayub, Marco A Z; Rodrigues, Rafael C

    2013-09-01

    The influence of low-frequency ultrasound (40 kHz) in the esterification reaction between acetic acid and butanol for flavor ester synthesis catalyzed by the commercial immobilized lipase B from Candida antarctica (Novozym 435) was evaluated. A central composite design and the response surface methodology were used to analyze the effects of the reaction parameters (temperature, substrate molar ratio, enzyme content and added water) and their response (yields of conversion in 2.5 h of reaction). The reaction was carried out using n-hexane as solvent. The optimal conditions for ultrasound-assisted butyl acetate synthesis were found to be: temperature of 46 °C; substrate molar ratio of 3.6:1 butanol:acetic acid; enzyme content of 7%; added water of 0.25%, conditions that are slightly different from those found using mechanical mixing. Over 94% of conversion was obtained in 2.5h under these conditions. The optimal acid concentration for the reaction was determined to be 2.0 M, compared to 0.3 M without ultrasound treatment. Enzyme productivity was significantly improved to around 7.5-fold for each batch when comparing ultrasound and standard mechanical agitation. The biocatalyst could be directly reused for 14 reactions cycles keeping around 70% of its original activity, while activity was virtually zeroed in the third cycle using the standard mixing system. Thus, compared to the traditional mechanical agitation, ultrasound technology not only improves the process productivity, but also enhances enzyme recycling and stability in the presence of acetic acid, being a powerful tool to improve biocatalyst performance in this type of reaction. PMID:23453821

  13. Enhancing human-animal relationships through veterinary medical instruction in animal-assisted therapy and animal-assisted activities.

    PubMed

    Schaffer, Caroline Brunsman

    2008-01-01

    Instruction in animal-assisted therapy (AAT) and animal-assisted activities (AAAs) teaches veterinary medical students to confidently and assertively maximize the benefits and minimize the risks of this union of animals and people. Instruction in AAT/AAA also addresses requirements by the American Veterinary Medical Association Council on Education that accredited schools/colleges of veterinary medicine include in their standard curriculum the topics of the human-animal bond, behavior, and the contributions of the veterinarian to the overall public and professional health care teams. Entry-level veterinarians should be prepared to: (1) assure that animals who provide AAT/AAA are healthy enough to visit nursing homes, hospitals, or other institutions; (2) promote behavior testing that selects animals who will feel safe, comfortable, and connected; (3) advise facilities regarding infection control and ways to provide a safe environment where the animals, their handlers, and the people being visited will not be injured or become ill; and (4) advocate for their patients and show compassion for their clients when animals are determined to be inappropriate participants in AAT/AAA programs. This article presents AAT/AAA terminology, ways in which veterinarians can advocate for AAT/AAA, the advantages of being involved in AAT/AAA, a model AAT/AAA practicum from Tuskegee University's School of Veterinary Medicine (TUSVM), and examples of co-curricular activities in AAT/AAA by TUSVM's student volunteers.

  14. Subchronic use of the St. Jude centrifugal pump as a mechanical assist device in calves.

    PubMed

    Curtis, J; Wagner-Mann, C; Mann, F; Demmy, T; Walls, J; Turk, J

    1996-06-01

    The purpose of this experiment was to study the effects of the St. Jude Lifestream centrifugal pump on hemodynamic and hematologic parameters and the incidence of postmortem findings in a subchronic ex vivo left ventricular assist animal model. Five calves were implanted with the pump as a left ventricular assist device (left atrial to thoracic aorta bypass) and studied for 96 h of continuous pumping under identical conditions. Heparin (100 IU/kg) was administered only in the initial saline pump prime. Throughout the protocol, mean arterial and central venous pressures averaged 102.1 +/- 4.6 and 3.4 +/- 2.2 mm Hg, respectively. Pump flow was 47.8 +/- 8.4 ml/kg/min at a mean pump speed of 1,676.3 +/- 106.1 rpm. No clinical abnormalities or mechanical malfunctions attributable to the pump were detected during the 96 h of continuous pumping for each calf. Mean plasma-free hemoglobin after 96 h was 3.9 +/- 3.7 mumol/L (p = 0.337 compared to baseline). At post mortem, renal infarctions were detected in 1 calf. No other pump-associated lesions were detected in any of the other calves. We have concluded that the St. Jude Lifestream centrifugal pump functions reliably during 96 h of continuous left heart bypass in a calf model.

  15. Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

    PubMed

    Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

    2010-09-01

    We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

  16. Levosimendan may improve survival in patients requiring mechanical assist devices for post-cardiotomy heart failure

    PubMed Central

    Braun, Jan-Peter; Jasulaitis, Dominik; Moshirzadeh, Maryam; Doepfmer, Ulrich R; Kastrup, Marc; von Heymann, Christian; Dohmen, Pascal M; Konertz, Wolfgang; Spies, Claudia

    2006-01-01

    Introduction Most case series suggest that less than half of the patients receiving a mechanical cardiac assist device as a bridge to recovery due to severe post-cardiotomy heart failure survive to hospital discharge. Levosimendan is the only inotropic substance known to improve medium term survival in patients suffering from severe heart failure. Methods This retrospective analysis covers our single centre experience. Between July 2000 and December 2004, 41 consecutive patients were treated for this complication. Of these, 38 patients are included in this retrospective analysis as 3 patients died in the operating room. Levosimendan was added to the treatment protocol for the last nine patients. Results Of 29 patients treated without levosimendan, 20 could be weaned off the device, 9 survived to intensive care unit discharge, 7 left hospital alive and 3 survived 180 days. All 9 patients treated with levosimendan could be weaned, 8 were discharged alive from ICU and hospital, and 7 lived 180 days after surgery (p < 0.002 for 180 day survival). Plasma lactate after explantation of the device was significantly lower (p = 0.002), as were epinephrine doses. Time spent on renal replacement therapy was significantly shorter (p = 0.023). Conclusion Levosimendan seems to improve medium term survival in patients failing to wean off cardiopulmonary bypass and requiring cardiac assist devices as a bridge to recovery. This retrospective analysis justifies prospective randomised investigations of levosimendan in this group of patients. PMID:16420666

  17. The mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water

    NASA Astrophysics Data System (ADS)

    Yu, Zhuanni; Chen, Xiaolin; Xia, Shuwei

    2016-06-01

    In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.

  18. Mechanism of Irradiation Assisted Cracking of Core Components in Light Water Reactors

    SciTech Connect

    Was, Gary S; Atzmon, Michael; Wang, Lumin

    2003-04-28

    The overall goal of the project is to determine the mechanism of irradiation assisted stress corrosion cracking (IASCC). IASCC has been linked to hardening, microstructural and microchemical changes during irradiation. Unfortunately, all of these changes occur simultaneously and at similar rates during irradiation, making attribution of IASCC to any one of these features nearly impossible to determine. The strategy set forth in this project is to develop means to separate microstructural from microchemical changes to evaluate each separately for their effect on IASCC. In the first part, post irradiation annealing (PIA) treatments are used to anneal the irradiated microstructure, leaving only radiation induced segregation (RIS) for evaluation for its contribution to IASCC. The second part of the strategy is to use low temperature irradiation to produce a radiation damage dislocation loop microstructure without radiation induced segregation in order to evaluate the effect of the dislocation microstructure alone.

  19. Group-Theoretical Calculation of the Diffusion Coefficient via the Vacancy-Assisted Mechanism

    NASA Astrophysics Data System (ADS)

    Okamoto, Ryuichi; Fujitani, Youhei

    2005-09-01

    Lower vacancy-density in a crystalline solid slows down the tracer diffusion via the vacancy-assisted mechanism, which can be modeled by means of particles hopping to their respective nearest-neighbor lattice-sites stochastically with double occupancy prohibited. The explicit expressions of the diffusion coefficient were previously obtained for various lattices in terms of Nakazato and Kitahara’s method [Prog. Theor. Phys. 64 (1980) 2261]. This method yields a set of linear simultaneous algebraic equations as many as the number of lattice sites, which is reduced to a simple equation with respect to the diffusion coefficient in the final step of the method. We here give a systematic way of the reduction in terms of the group theory.

  20. Resident-Assisted Montessori Programming (Ramp): Training Persons with Dementia to Serve as Group Activity Leaders

    ERIC Educational Resources Information Center

    Camp, Cameron J.; Skrajner, Michael J.

    2004-01-01

    Purpose: The purpose of this study was to determine the effects of an activity implemented by means of Resident-Assisted Montessori Programming (RAMP). Design and Methods: Four persons with early-stage dementia were trained to serve as leaders for a small-group activity played by nine persons with more advanced dementia. Assessments of leaders'…

  1. Mechanically assisted 3D prostate ultrasound imaging and biopsy needle-guidance system

    NASA Astrophysics Data System (ADS)

    Bax, Jeffrey; Williams, Jackie; Cool, Derek; Gardi, Lori; Montreuil, Jacques; Karnik, Vaishali; Sherebrin, Shi; Romagnoli, Cesare; Fenster, Aaron

    2010-02-01

    Prostate biopsy procedures are currently limited to using 2D transrectal ultrasound (TRUS) imaging to guide the biopsy needle. Being limited to 2D causes ambiguity in needle guidance and provides an insufficient record to allow guidance to the same suspicious locations or avoid regions that are negative during previous biopsy sessions. We have developed a mechanically assisted 3D ultrasound imaging and needle tracking system, which supports a commercially available TRUS probe and integrated needle guide for prostate biopsy. The mechanical device is fixed to a cart and the mechanical tracking linkage allows its joints to be manually manipulated while fully supporting the weight of the ultrasound probe. The computer interface is provided in order to track the needle trajectory and display its path on a corresponding 3D TRUS image, allowing the physician to aim the needle-guide at predefined targets within the prostate. The system has been designed for use with several end-fired transducers that can be rotated about the longitudinal axis of the probe in order to generate 3D image for 3D navigation. Using the system, 3D TRUS prostate images can be generated in approximately 10 seconds. The system reduces most of the user variability from conventional hand-held probes, which make them unsuitable for precision biopsy, while preserving some of the user familiarity and procedural workflow. In this paper, we describe the 3D TRUS guided biopsy system and report on the initial clinical use of this system for prostate biopsy.

  2. Promoting Technology-Assisted Active Learning in Computer Science Education

    ERIC Educational Resources Information Center

    Gao, Jinzhu; Hargis, Jace

    2010-01-01

    This paper describes specific active learning strategies for teaching computer science, integrating both instructional technologies and non-technology-based strategies shown to be effective in the literature. The theoretical learning components addressed include an intentional method to help students build metacognitive abilities, as well as…

  3. 78 FR 46829 - Assistance to Foreign Atomic Energy Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-02

    ..., Russia, and Canada having emerged to serve customers in these emerging markets. DOE believes the..., 2011, DOE issued a NOPR to propose the updating of part 810 (76 FR 55278). The NOPR listed destinations... activities subject to part 810. 48 FR 2518 (Feb. 4, 1983); 40 FR 44846 (Sep. 30, 1975); 21 FR 418 (Jan....

  4. 76 FR 55278 - Assistance to Foreign Atomic Energy Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... thorium mining and milling and nuclear fusion reactors when not used in support of systems involving... activities related to uranium and thorium mining and milling and nuclear fusion reactors, per se, are not...; and (4) Nuclear fusion reactors per se, except for supporting systems involving hydrogen...

  5. Performance of daily activities by older adults with dementia: the role of an assistive robot.

    PubMed

    Begum, Momotaz; Wang, Rosalie; Huq, Rajibul; Mihailidis, Alex

    2013-06-01

    Older adults with cognitive impairment often have difficulties in remembering the proper sequence of activities of daily living (ADLs) or how to use the tools necessary to perform ADLs. They, therefore, require reminders in a timely fashion while performing ADLs. This is a very stressful situation for the caregivers of people with dementia. In this paper we describe a pilot study where a tele-operated assistive robot helps a group of older adults with dementia (OAwD) to perform an ADL, namely making a cup of tea in the kitchen. Five OAwD along with their caregivers participated in this study which took place in a simulated-home setting. The purpose of this study was to investigate the feasibility and usability of a robotic system in assisting the OAwD to perform ADL in a home setting. The findings from this study will contribute to achieve our ultimate goal of designing a full-fledged assistive robot that assists OAwD aging in their own homes. The assistive robots designed for people with dementia mostly focus on companionship. This is, to the best of our knowledge, the first attempt to design an assistive robot which will provide step-by-step guidance to people with dementia in their activities of daily living. PMID:24187224

  6. Assessment of Initial Test Conditions for Experiments to Assess Irradiation Assisted Stress Corrosion Cracking Mechanisms

    SciTech Connect

    Busby, Jeremy T; Gussev, Maxim N

    2011-04-01

    Irradiation-assisted stress corrosion cracking is a key materials degradation issue in today s nuclear power reactor fleet and affects critical structural components within the reactor core. The effects of increased exposure to irradiation, stress, and/or coolant can substantially increase susceptibility to stress-corrosion cracking of austenitic steels in high-temperature water environments. . Despite 30 years of experience, the underlying mechanisms of IASCC are unknown. Extended service conditions will increase the exposure to irradiation, stress, and corrosive environment for all core internal components. The objective of this effort within the Light Water Reactor Sustainability program is to evaluate the response and mechanisms of IASCC in austenitic stainless steels with single variable experiments. A series of high-value irradiated specimens has been acquired from the past international research programs, providing a valuable opportunity to examine the mechanisms of IASCC. This batch of irradiated specimens has been received and inventoried. In addition, visual examination and sample cleaning has been completed. Microhardness testing has been performed on these specimens. All samples show evidence of hardening, as expected, although the degree of hardening has saturated and no trend with dose is observed. Further, the change in hardening can be converted to changes in mechanical properties. The calculated yield stress is consistent with previous data from light water reactor conditions. In addition, some evidence of changes in deformation mode was identified via examination of the microhardness indents. This analysis may provide further insights into the deformation mode under larger scale tests. Finally, swelling analysis was performed using immersion density methods. Most alloys showed some evidence of swelling, consistent with the expected trends for this class of alloy. The Hf-doped alloy showed densification rather than swelling. This observation may be

  7. International Assistance for Low-Emission Development Planning: Coordinated Low Emissions Assistance Network (CLEAN) Inventory of Activities and Tools--Preliminary Trends

    SciTech Connect

    Cox, S.; Benioff, R.

    2011-05-01

    The Coordinated Low Emissions Assistance Network (CLEAN) is a voluntary network of international practitioners supporting low-emission planning in developing countries. The network seeks to improve quality of support through sharing project information, tools, best practices and lessons, and by fostering harmonized assistance. CLEAN has developed an inventory to track and analyze international technical support and tools for low-carbon planning activities in developing countries. This paper presents a preliminary analysis of the inventory to help identify trends in assistance activities and tools available to support developing countries with low-emission planning.

  8. The Solar Thermal Design Assistance Center report of its activities and accomplishments in Fiscal Year 1993

    SciTech Connect

    Menicucci, D.F.

    1994-03-01

    The Solar Thermal Design Assistance Center (STDAC) at Sandia National Laboratories is a resource provided by the US Department of Energy`s Solar Thermal Program. Its major objectives are to accelerate the use of solar thermal systems through (a) direct technical assistance to users, (b) cooperative test, evaluation, and development efforts with private industry, and (c) educational outreach activities. This report outlines the major activities and accomplishments of the STDAC in Fiscal Year 1993. The report also contains a comprehensive list of persons who contacted the STDAC by telephone for information or technical consulting.

  9. Mechanisms of Specificity for Hox Factor Activity

    PubMed Central

    Zandvakili, Arya; Gebelein, Brian

    2016-01-01

    Metazoans encode clusters of paralogous Hox genes that are critical for proper development of the body plan. However, there are a number of unresolved issues regarding how paralogous Hox factors achieve specificity to control distinct cell fates. First, how do Hox paralogs, which have very similar DNA binding preferences in vitro, drive different transcriptional programs in vivo? Second, the number of potential Hox binding sites within the genome is vast compared to the number of sites bound. Hence, what determines where in the genome Hox factors bind? Third, what determines whether a Hox factor will activate or repress a specific target gene? Here, we review the current evidence that is beginning to shed light onto these questions. In particular, we highlight how cooperative interactions with other transcription factors (especially PBC and HMP proteins) and the sequences of cis-regulatory modules provide a basis for the mechanisms of Hox specificity. We conclude by integrating a number of the concepts described throughout the review in a case study of a highly interrogated Drosophila cis-regulatory module named “The Distal-less Conserved Regulatory Element” (DCRE). PMID:27583210

  10. Mechanical blood trauma in assisted circulation: sublethal RBC damage preceding hemolysis.

    PubMed

    Olia, Salim E; Maul, Timothy M; Antaki, James F; Kameneva, Marina V

    2016-06-15

    After many decades of improvements in mechanical circulatory assist devices (CADs), blood damage remains a serious problem during support contributing to variety of adverse events, and consequently affecting patient survival and quality of life. The mechanisms of cumulative cell damage in continuous-flow blood pumps are still not fully understood despite numerous in vitro, in vivo, and in silico studies of blood trauma. Previous investigations have almost exclusively focused on lethal blood damage, namely hemolysis, which is typically negligible during normal operation of current generation CADs. The measurement of plasma free hemoglobin (plfHb) concentration to characterize hemolysis is straightforward, however sublethal trauma is more difficult to detect and quantify since no simple direct test exists. Similarly, while multiple studies have focused on thrombosis within blood pumps and accessories, sublethal blood trauma and its sequelae have yet to be adequately documented or characterized. This review summarizes the current understanding of sublethal trauma to red blood cells (RBCs) produced by exposure of blood to flow parameters and conditions similar to those within CADs. It also suggests potential strategies to reduce and/or prevent RBC sublethal damage in a clinically-relevant context, and encourages new research into this relatively uncharted territory.

  11. Debug of IC-card chips assisted by FIB and in-situ mechanical microprobing

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao D.; Yu, Xiang H.; Lundquist, Theodore R.

    2001-10-01

    The value of mechanical micro-probes and FIB in IC design-debug is well understood. As device dimensions shrink, navigating micro-probes within a light microscope is almost impossible. SEM or FIB, which have higher resolution as well as greater depth of focus, overcome this limitation. FIB is, also, preferred for DUT probe-point creation because its higher milling resolution capability can provide better access to lower level metallizations. IC-card chips present an unique challenge; the backside of these are often insulated so grounding must occur on the exposed front-side. Further, because these IC-card chips are small, very careful setups are required before undertaking FIB modifications. Micro-probes within the FIB chamber solved this problem. Three micro-probes were used to stimulate the chip (input-clock, ground and power) with a fourth probe used to measure output nodes. Requested FIB modifications, including rewiring of poly-silicon traces, were completed. Contacting poly-silicon requires FIB-assisted XeF2 etching through the inter-level dielectric and both fast termination and removal of XeF2 from the chamber upon poly-silicon exposure. The technique for exposing poly-silicon is described in detail. The synergy of mechanical micro-probes within the FIB chamber benefited both techniques in the design-debug task. We summarize various IC-card packaging styles and requirements to ground, micro-probe, and establish a debug platform.

  12. Safety mechanism assisted by the repressor of tetracycline (SMART) vaccinia virus vectors for vaccines and therapeutics.

    PubMed

    Grigg, Patricia; Titong, Allison; Jones, Leslie A; Yilma, Tilahun D; Verardi, Paulo H

    2013-09-17

    Replication-competent viruses, such as Vaccinia virus (VACV), are powerful tools for the development of oncolytic viral therapies and elicit superior immune responses when used as vaccine and immunotherapeutic vectors. However, severe complications from uncontrolled viral replication can occur, particularly in immunocompromised individuals or in those with other predisposing conditions. VACVs constitutively expressing interferon-γ (IFN-γ) replicate in cell culture indistinguishably from control viruses; however, they replicate in vivo to low or undetectable levels, and are rapidly cleared even in immunodeficient animals. In an effort to develop safe and highly effective replication-competent VACV vectors, we established a system to inducibly express IFN-γ. Our SMART (safety mechanism assisted by the repressor of tetracycline) vectors are designed to express the tetracycline repressor under a constitutive VACV promoter and IFN-γ under engineered tetracycline-inducible promoters. Immunodeficient SCID mice inoculated with VACVs not expressing IFN-γ demonstrated severe weight loss, whereas those given VACVs expressing IFN-γ under constitutive VACV promoters showed no signs of infection. Most importantly, mice inoculated with a VACV expressing the IFN-γ gene under an inducible promoter remained healthy in the presence of doxycycline, but exhibited severe weight loss in the absence of doxycycline. In this study, we developed a safety mechanism for VACV based on the conditional expression of IFN-γ under a tightly controlled tetracycline-inducible VACV promoter for use in vaccines and oncolytic cancer therapies.

  13. Safety and Feasibility of Laparoscopic Abdominal Surgery in Patients With Mechanical Circulatory Assist Devices.

    PubMed

    Ashfaq, Awais; Chapital, Alyssa B; Johnson, Daniel J; Staley, Linda L; Arabia, Francisco A; Harold, Kristi L

    2016-10-01

    Objectives Increasing number of mechanical circulatory assist devices (MCADs) are being placed in heart failure patients. Morbidity from device placement is high and the outcome of patients who require noncardiac surgery after, is unclear. As laparoscopic interventions are associated with decreased morbidity, we examined the impact of such procedures in these patients. Methods A retrospective review was conducted on 302 patients who underwent MCAD placement from 2005 to 2012. All laparoscopic abdominal surgeries were included and impact on postoperative morbidity and mortality studied. Results Ten out of 16 procedures were laparoscopic with 1 conversion to open. Seven patients had a HeartMate II, 2 had Total Artificial Hearts, and 1 had CentriMag. Four patients had devices for ischemic cardiomyopathy and 6 cases were emergent. Surgeries included 6 laparoscopic cholecystectomies, 2 exploratory laparoscopies, 1 laparoscopic colostomy takedown, and 1 laparoscopic ventral hernia repair with mesh. Median age of the patients was 63 years (range, 29-79 years). Median operative time was 123 minutes (range, 30-380 minutes). Five of 10 patients were on preoperative anticoagulation with average intraoperative blood loss of 150 mL (range, 20-700 mL). There were 3 postoperative complications; acute respiratory failure, acute kidney injury and multisystem organ failure resulting in death not related to the surgical procedure. Conclusion The need for noncardiac surgery in post-MCAD patients is increasing due to limited donors and due to more durable and longer support from newer generation assist devices. While surgery should be approached with caution in this high-risk group, laparoscopic surgery appears to be a safe and successful treatment option. PMID:26839214

  14. Vision based assistive technology for people with dementia performing activities of daily living (ADLs): an overview

    NASA Astrophysics Data System (ADS)

    As'ari, M. A.; Sheikh, U. U.

    2012-04-01

    The rapid development of intelligent assistive technology for replacing a human caregiver in assisting people with dementia performing activities of daily living (ADLs) promises in the reduction of care cost especially in training and hiring human caregiver. The main problem however, is the various kinds of sensing agents used in such system and is dependent on the intent (types of ADLs) and environment where the activity is performed. In this paper on overview of the potential of computer vision based sensing agent in assistive system and how it can be generalized and be invariant to various kind of ADLs and environment. We find that there exists a gap from the existing vision based human action recognition method in designing such system due to cognitive and physical impairment of people with dementia.

  15. THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE

    SciTech Connect

    Jordan, G. C. IV; Graziani, C.; Weide, K.; Norris, J.; Hudson, R.; Lamb, D. Q.; Fisher, R. T.; Townsley, D. M.; Meakin, C.; Reid, L. B.

    2012-11-01

    We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.

  16. The Detonation Mechanism of the Pulsationally Assisted Gravitationally Confined Detonation Model of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Jordan, G. C., IV; Graziani, C.; Fisher, R. T.; Townsley, D. M.; Meakin, C.; Weide, K.; Reid, L. B.; Norris, J.; Hudson, R.; Lamb, D. Q.

    2012-11-01

    We describe the detonation mechanism composing the "pulsationally assisted" gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and 56Ni yields conform better to observational values than is the case for the "classical" GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.

  17. 34 CFR 642.10 - Activities the Secretary assists under the Training Program.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Training Program projects must provide training for new project directors. (d) Each year, one or more... 34 Education 3 2010-07-01 2010-07-01 false Activities the Secretary assists under the Training... (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION TRAINING PROGRAM FOR FEDERAL...

  18. Teaching Middle School Students with Learning Disabilities To Recruit Peer Assistance during Cooperative Learning Group Activities.

    ERIC Educational Resources Information Center

    Wolford, Patricia L.; Heward, William L.; Alber, Sheila R.

    2001-01-01

    Four 8th graders with learning disabilities were taught to recruit assistance from peers during cooperative learning activities in two general classrooms. Training consisted of modeling, role playing, corrective feedback, and praise. Recruitment training increased the productivity and accuracy with which the students completed their language arts…

  19. Assisting Persons with Multiple Disabilities to Move through Simple Occupational Activities with Automatic Prompting

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Oliva, Doretta; Campodonico, Francesca; Groeneweg, Jop

    2008-01-01

    The present study assessed the possibility of assisting four persons with multiple disabilities to move through and perform simple occupational activities arranged within a room with the help of automatic prompting. The study involved two multiple probe designs across participants. The first multiple probe concerned the two participants with…

  20. Effects of an Equine Assisted Activities Program on Youth with Emotional Disturbance: A Pilot Study

    ERIC Educational Resources Information Center

    Stebbins, Tira

    2012-01-01

    This study evaluated the effects of a 10-week Equine Assisted Activities (EAA) program on special education students (aged 9 to 15) identified as Emotionally Disturbed (ED) who were enrolled in an alternative school. A control group of special education students receiving treatment-as-usual was included. The Behavior Assessment Scale for Children,…

  1. 34 CFR 660.10 - What activities does the Secretary assist?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false What activities does the Secretary assist? 660.10 Section 660.10 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION THE INTERNATIONAL RESEARCH AND STUDIES PROGRAM What Kinds...

  2. 24 CFR 570.210 - Prohibition on use of assistance for employment relocation activities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... PLANNING AND DEVELOPMENT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT COMMUNITY FACILITIES COMMUNITY... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Prohibition on use of assistance for employment relocation activities. 570.210 Section 570.210 Housing and Urban...

  3. 34 CFR 654.3 - What kind of activity may be assisted?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false What kind of activity may be assisted? 654.3 Section 654.3 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION ROBERT C. BYRD HONORS SCHOLARSHIP PROGRAM General § 654.3...

  4. Part 110--Nondiscrimination on the Basis of Age in Programs or Activities Receiving Federal Financial Assistance.

    ERIC Educational Resources Information Center

    Office for Civil Rights (ED), Washington, DC.

    This document addresses nondiscrimination on the basis of age in programs or activities receiving federal financial assistance. It consists of the amendments made in the notice of Final Regulations published in the Federal Register on November 13, 2000. Its purpose is to set out the Department of Education's rules for implementing the Age…

  5. 78 FR 28569 - Nondiscrimination on the Basis of Age in Federally Assisted Programs or Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-15

    ... first proposed agency-specific regulations implementing the Act on October 4, 1979 (44 FR 57130), which... Nondiscrimination on the Basis of Age in Federally Assisted Programs or Activities AGENCY: National Endowment for... National Endowment for the Humanities (NEH) is issuing Age Discrimination Act of 1975 regulations at 45...

  6. Health Occupations--Dental Assistant. Kit No. 62. Instructor's Manual [and] Student Learning Activity Guide.

    ERIC Educational Resources Information Center

    Jackson, Janette

    An instructor's manual and student activity guide on a dental assistant are provided in this set of prevocational education materials which focuses on the vocational area of health occupations. (This set of materials is one of ninety-two prevocational education sets arranged around a cluster of seven vocational offerings: agriculture, home…

  7. 48 CFR Appendix F to Chapter 7 - Use of Collaborative Assistance Method for Title XII Activities

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... problem areas of great complexity and varying uncertainty. Other types of technical assistance, which are... and the USAID field mission has determined that the proposed activity is consistent with its program... Agreement and other pertinent documentation. The field review will normally serve as the occasion...

  8. 48 CFR Appendix F to Chapter 7 - Use of Collaborative Assistance Method for Title XII Activities

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... problem areas of great complexity and varying uncertainty. Other types of technical assistance, which are... and the USAID field mission has determined that the proposed activity is consistent with its program... Agreement and other pertinent documentation. The field review will normally serve as the occasion...

  9. 76 FR 42129 - Agency Information Collection Activities: Case Submission Form, Case Assistance Form

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... SECURITY Agency Information Collection Activities: Case Submission Form, Case Assistance Form (Form DHS-7001), Online Ombudsman Form DHS-7001 AGENCY: Office of the Citizenship and Immigration Service... practices of USCIS to mitigate problems. This form is used by an applicant who is experiencing problems...

  10. Recent advances in computational methodology for simulation of mechanical circulatory assist devices

    PubMed Central

    Marsden, Alison L.; Bazilevs, Yuri; Long, Christopher C.; Behr, Marek

    2014-01-01

    Ventricular assist devices (VADs) provide mechanical circulatory support to offload the work of one or both ventricles during heart failure. They are used in the clinical setting as destination therapy, as bridge to transplant, or more recently as bridge to recovery to allow for myocardial remodeling. Recent developments in computational simulation allow for detailed assessment of VAD hemodynamics for device design and optimization for both children and adults. Here, we provide a focused review of the recent literature on finite element methods and optimization for VAD simulations. As VAD designs typically fall into two categories, pulsatile and continuous flow devices, we separately address computational challenges of both types of designs, and the interaction with the circulatory system with three representative case studies. In particular, we focus on recent advancements in finite element methodology that has increased the fidelity of VAD simulations. We outline key challenges, which extend to the incorporation of biological response such as thrombosis and hemolysis, as well as shape optimization methods and challenges in computational methodology. PMID:24449607

  11. A study on dynamic heat assisted magnetization reversal mechanisms under insufficient reversal field conditions

    SciTech Connect

    Chen, Y. J.; Yang, H. Z.; Leong, S. H.; Yu Ko, Hnin Yu; Wu, B. L.; Ng, V.; Asbahi, M.; Yang, J. K. W.

    2014-10-20

    We report an experimental study on the dynamic thermomagnetic (TM) reversal mechanisms at around Curie temperature (Tc) for isolated 60 nm pitch single-domain [Co/Pd] islands heated by a 1.5 μm spot size laser pulse under an applied magnetic reversal field (Hr). Magnetic force microscopy (MFM) observations with high resolution MFM tips clearly showed randomly trapped non-switched islands within the laser irradiated spot after dynamic TM reversal process with insufficient Hr strength. This observation provides direct experimental evidence by MFM of a large magnetization switching variation due to increased thermal fluctuation/agitation over magnetization energy at the elevated temperature of around Tc. The average percentage of non-switched islands/magnetization was further found to be inversely proportional to the applied reversal field Hr for incomplete magnetization reversal when Hr is less than 13% of the island coercivity (Hc), showing an increased switching field distribution (SFD) at elevated temperature of around Tc (where main contributions to SFD broadening are from Tc distribution and stronger thermal fluctuations). Our experimental study and results provide better understanding and insight on practical heat assisted magnetic recording (HAMR) process and recording performance, including HAMR writing magnetization dynamics induced SFD as well as associated DC saturation noise that limits areal density, as were previously observed and investigated by theoretical simulations.

  12. Vascular dysfunction in children conceived by assisted reproductive technologies: underlying mechanisms and future implications.

    PubMed

    Rimoldi, Stefano F; Sartori, Claudio; Rexhaj, Emrush; Cerny, David; Von Arx, Robert; Soria, Rodrigo; Germond, Marc; Allemann, Yves; Scherrer, Urs

    2014-01-01

    Epidemiological studies in humans have demonstrated a relationship between pathological events during fetal development and increased cardiovascular risk later in life and have led to the so called "Fetal programming of cardiovascular disease hypothesis". The recent observation of generalised vascular dysfunction in young apparently healthy children conceived by assisted reproductive technologies (ART) provides a novel and potentially very important example of this hypothesis. This review summarises recent data in ART children demonstrating premature subclinical atherosclerosis in the systemic circulation and pulmonary vascular dysfunction predisposing to exaggerated hypoxia-induced pulmonary hypertension. These problems appear to be related to the ART procedure per se. Studies in ART mice demonstrating premature vascular aging and arterial hypertension further demonstrate the potential of ART to increase cardiovascular risk and have allowed to unravel epigenetic alterations of the eNOS gene as an underpinning mechanism. The roughly 25% shortening of the life span in ART mice challenged with a western style high-fat-diet demonstrates the potential importance of these alterations for the long-term outcome. Given the young age of the ART population, data on cardiovascular endpoints will not be available before 20 to 30 years from now. However, already now cohort studies of the ART population are needed to early detect cardiovascular alterations with the aim to prevent or at least optimally treat cardiovascular complications. Finally, a debate needs to be engaged on the future of ART and the consequences of its exponential growth for public health. PMID:24964004

  13. Strong magnetic field-assisted growth of carbon nanofibers and its microstructural transformation mechanism

    PubMed Central

    Luo, Chengzhi; Fu, Qiang; Pan, Chunxu

    2015-01-01

    It is well-known that electric and magnetic fields can control the growth direction, morphology and microstructure of one-dimensional carbon nanomaterials (1-DCNMs), which plays a key role for its potential applications in micro-nano-electrics and devices. In this paper, we introduce a novel process for controlling growth of carbon nanofibers (CNFs) with assistance of a strong magnetic field (up to 0.5 T in the center) in a chemical vapor deposition (CVD) system. The results reveal that: 1) The CNFs get bundled when grown in the presence of a strong magnetic field and slightly get aligned parallel to the direction of the magnetic field; 2) The CNFs diameter become narrowed and homogenized with increase of the magnetic field; 3) With the increase of the magnetic field, the microstructure of CNFs is gradually changed, i.e., the strong magnetic field makes the disordered “solid-cored” CNFs transform into a kind of bamboo-liked carbon nanotubes; 4) We propose a mechanism that the reason for these variations and transformation is due to diamagnetic property of carbon atoms, so that it has direction selectivity in the precipitation process. PMID:25761381

  14. A study on dynamic heat assisted magnetization reversal mechanisms under insufficient reversal field conditions

    NASA Astrophysics Data System (ADS)

    Chen, Y. J.; Yang, H. Z.; Leong, S. H.; Wu, B. L.; Asbahi, M.; Yu Ko, Hnin Yu; Yang, J. K. W.; Ng, V.

    2014-10-01

    We report an experimental study on the dynamic thermomagnetic (TM) reversal mechanisms at around Curie temperature (Tc) for isolated 60 nm pitch single-domain [Co/Pd] islands heated by a 1.5 μm spot size laser pulse under an applied magnetic reversal field (Hr). Magnetic force microscopy (MFM) observations with high resolution MFM tips clearly showed randomly trapped non-switched islands within the laser irradiated spot after dynamic TM reversal process with insufficient Hr strength. This observation provides direct experimental evidence by MFM of a large magnetization switching variation due to increased thermal fluctuation/agitation over magnetization energy at the elevated temperature of around Tc. The average percentage of non-switched islands/magnetization was further found to be inversely proportional to the applied reversal field Hr for incomplete magnetization reversal when Hr is less than 13% of the island coercivity (Hc), showing an increased switching field distribution (SFD) at elevated temperature of around Tc (where main contributions to SFD broadening are from Tc distribution and stronger thermal fluctuations). Our experimental study and results provide better understanding and insight on practical heat assisted magnetic recording (HAMR) process and recording performance, including HAMR writing magnetization dynamics induced SFD as well as associated DC saturation noise that limits areal density, as were previously observed and investigated by theoretical simulations.

  15. Pearls and pitfalls in short-term mechanical circulatory assist: how to avoid and manage complications.

    PubMed

    Mohite, Prashant N; Maunz, Olaf; Simon, Andre R

    2014-10-01

    In today's era, given the worsening risk profiles of patients undergoing cardiac surgery, the increasing number of complex cardiac surgeries, and the increasing number of patients undergoing thoracic organ transplantation, short-term mechanical circulatory assist (MCA) devices are indispensable. MCA devices are capable of supporting heart and lung function and have emerged as potentially lifesaving instruments, but may prove to be as hazardous as helpful due to their inherent tendency toward hemolysis, thromboembolism, and hemorrhage. Although MCA devices are being used regularly at some specialized centers, surgeries involving MCA are not as common as other routine cardiac surgeries, and even though professionals implanting and maintaining short-term MCAs are well acquainted with operating such devices, it is not uncommon to come across complications as a result of minor mistakes committed while dealing with them. Avoiding simple mistakes and taking proper precautions while implanting and maintaining these devices can prevent major catastrophes. We discuss commonly encountered problems and complications during the implantation and maintenance of short-term MCAs and offer reasonable and practical solutions. In addition, crucial issues such as anticoagulation, replacement of the device circuit, and management of the distal perfusion cannula are discussed. Continuous and efficient monitoring of the MCA device and the patient supported on MCA, together with anticipation and avoidance of complications, is key for successful short-term MCA support.

  16. Strong magnetic field-assisted growth of carbon nanofibers and its microstructural transformation mechanism.

    PubMed

    Luo, Chengzhi; Fu, Qiang; Pan, Chunxu

    2015-01-01

    It is well-known that electric and magnetic fields can control the growth direction, morphology and microstructure of one-dimensional carbon nanomaterials (1-DCNMs), which plays a key role for its potential applications in micro-nano-electrics and devices. In this paper, we introduce a novel process for controlling growth of carbon nanofibers (CNFs) with assistance of a strong magnetic field (up to 0.5 T in the center) in a chemical vapor deposition (CVD) system. The results reveal that: 1) The CNFs get bundled when grown in the presence of a strong magnetic field and slightly get aligned parallel to the direction of the magnetic field; 2) The CNFs diameter become narrowed and homogenized with increase of the magnetic field; 3) With the increase of the magnetic field, the microstructure of CNFs is gradually changed, i.e., the strong magnetic field makes the disordered "solid-cored" CNFs transform into a kind of bamboo-liked carbon nanotubes; 4) We propose a mechanism that the reason for these variations and transformation is due to diamagnetic property of carbon atoms, so that it has direction selectivity in the precipitation process. PMID:25761381

  17. Strong magnetic field-assisted growth of carbon nanofibers and its microstructural transformation mechanism

    NASA Astrophysics Data System (ADS)

    Luo, Chengzhi; Fu, Qiang; Pan, Chunxu

    2015-03-01

    It is well-known that electric and magnetic fields can control the growth direction, morphology and microstructure of one-dimensional carbon nanomaterials (1-DCNMs), which plays a key role for its potential applications in micro-nano-electrics and devices. In this paper, we introduce a novel process for controlling growth of carbon nanofibers (CNFs) with assistance of a strong magnetic field (up to 0.5 T in the center) in a chemical vapor deposition (CVD) system. The results reveal that: 1) The CNFs get bundled when grown in the presence of a strong magnetic field and slightly get aligned parallel to the direction of the magnetic field; 2) The CNFs diameter become narrowed and homogenized with increase of the magnetic field; 3) With the increase of the magnetic field, the microstructure of CNFs is gradually changed, i.e., the strong magnetic field makes the disordered ``solid-cored'' CNFs transform into a kind of bamboo-liked carbon nanotubes; 4) We propose a mechanism that the reason for these variations and transformation is due to diamagnetic property of carbon atoms, so that it has direction selectivity in the precipitation process.

  18. Substrate-Assisted Catalysis in the Reaction Catalyzed by Salicylic Acid Binding Protein 2 (SABP2), a Potential Mechanism of Substrate Discrimination for Some Promiscuous Enzymes.

    PubMed

    Yao, Jianzhuang; Guo, Haobo; Chaiprasongsuk, Minta; Zhao, Nan; Chen, Feng; Yang, Xiaohan; Guo, Hong

    2015-09-01

    Although one of an enzyme's hallmarks is the high specificity for their natural substrates, substrate promiscuity has been reported more frequently. It is known that promiscuous enzymes generally show different catalytic efficiencies to different substrates, but our understanding of the origin of such differences is still lacking. Here we report the results of quantum mechanical/molecular mechanical simulations and an experimental study of salicylic acid binding protein 2 (SABP2). SABP2 has promiscuous esterase activity toward a series of substrates but shows a high activity toward its natural substrate, methyl salicylate (MeSA). Our results demonstrate that this enzyme may use substrate-assisted catalysis involving the hydroxyl group from MeSA to enhance the activity and achieve substrate discrimination. PMID:26244568

  19. Substrate-Assisted Catalysis in the Reaction Catalyzed by Salicylic Acid Binding Protein 2 (SABP2), a Potential Mechanism of Substrate Discrimination for Some Promiscuous Enzymes

    DOE PAGESBeta

    Yao, Jianzhuang; Guo, Haobo; Chaiprasongsuk, Minta; Zhao, Nan; Chen, Feng; Yang, Xiaohan; Guo, Hong

    2015-08-05

    Although one of an enzyme’s hallmarks is the high specificity for their natural substrates, substrate promiscuity has been reported more frequently. We know that promiscuous enzymes generally show different catalytic efficiencies to different substrates, but our understanding of the origin of such differences is still lacking. We report the results of quantum mechanical/molecular mechanical simulations and an experimental study of salicylic acid binding protein 2 (SABP2). SABP2 has promiscuous esterase activity toward a series of substrates but shows a high activity toward its natural substrate, methyl salicylate (MeSA). Finally, our results demonstrate that this enzyme may use substrate-assisted catalysis involvingmore » the hydroxyl group from MeSA to enhance the activity and achieve substrate discrimination.« less

  20. Substrate-Assisted Catalysis in the Reaction Catalyzed by Salicylic Acid Binding Protein 2 (SABP2), a Potential Mechanism of Substrate Discrimination for Some Promiscuous Enzymes

    SciTech Connect

    Yao, Jianzhuang; Guo, Haobo; Chaiprasongsuk, Minta; Zhao, Nan; Chen, Feng; Yang, Xiaohan; Guo, Hong

    2015-08-05

    Although one of an enzyme’s hallmarks is the high specificity for their natural substrates, substrate promiscuity has been reported more frequently. We know that promiscuous enzymes generally show different catalytic efficiencies to different substrates, but our understanding of the origin of such differences is still lacking. We report the results of quantum mechanical/molecular mechanical simulations and an experimental study of salicylic acid binding protein 2 (SABP2). SABP2 has promiscuous esterase activity toward a series of substrates but shows a high activity toward its natural substrate, methyl salicylate (MeSA). Finally, our results demonstrate that this enzyme may use substrate-assisted catalysis involving the hydroxyl group from MeSA to enhance the activity and achieve substrate discrimination.

  1. Substrate-Assisted Catalysis in the Reaction Catalyzed by Salicylic Acid Binding Protein 2 (SABP2), a Potential Mechanism of Substrate Discrimination for Some Promiscuous Enzymes.

    PubMed

    Yao, Jianzhuang; Guo, Haobo; Chaiprasongsuk, Minta; Zhao, Nan; Chen, Feng; Yang, Xiaohan; Guo, Hong

    2015-09-01

    Although one of an enzyme's hallmarks is the high specificity for their natural substrates, substrate promiscuity has been reported more frequently. It is known that promiscuous enzymes generally show different catalytic efficiencies to different substrates, but our understanding of the origin of such differences is still lacking. Here we report the results of quantum mechanical/molecular mechanical simulations and an experimental study of salicylic acid binding protein 2 (SABP2). SABP2 has promiscuous esterase activity toward a series of substrates but shows a high activity toward its natural substrate, methyl salicylate (MeSA). Our results demonstrate that this enzyme may use substrate-assisted catalysis involving the hydroxyl group from MeSA to enhance the activity and achieve substrate discrimination.

  2. Mechanisms of defect complex formation and environmental-assisted fracture behavior of iron aluminides

    SciTech Connect

    Cooper, B.R.; Muratov, L.S.; Kang, B.S.J.; Li, K.Z.

    1997-12-01

    Iron aluminide has excellent corrosion resistance in high-temperature oxidizing-sulfidizing environments; however, there are problems at room and medium temperature with hydrogen embrittlement as related to exposure to moisture. In this research, a coordinated computational modeling/experimental study of mechanisms related to environmental-assisted fracture behavior of selected iron aluminides is being undertaken. The modeling and the experimental work will connect at the level of coordinated understanding of the mechanisms for hydrogen penetration and for loss of strength and susceptibility to fracture. The focus of the modeling component at this point is on the challenging question of accurately predicting the iron vacancy formation energy in Fe{sub 3}A{ell} and the subsequent tendency, if present, for vacancy clustering. The authors have successfully performed, on an ab initio basis, the first calculation of the vacancy formation energy in Fe{sub 3}A{ell}. These calculations include lattice relaxation effects which are quite large. This has significant implications for vacancy clustering effects with consequences to be explored for hydrogen diffusion. The experimental work at this stage has focused on the relationship of the choice and concentration of additives to the improvement of resistance to hydrogen embrittlement and hence to the fracture behavior. For this reason, comparative crack growth tests of FA-186, FA-187, and FA-189 iron aluminides (all with basic composition of Fe-28A{ell}-5Cr, at % with micro-alloying additives of Zr, C or B) under, air, oxygen, or water environment have been performed. These tests showed that the alloys are susceptible to room temperature hydrogen embrittlement in both B2 and DO{sub 3} conditions. Test results indicated that FA-187, and FA-189 are intrinsically more brittle than FA-186.

  3. The mechanism of copper activation of sphalerite

    NASA Astrophysics Data System (ADS)

    Gerson, Andrea R.; Lange, Angela G.; Prince, Kathryn E.; Smart, Roger St. C.

    1999-01-01

    On the basis of recent SIMS and XAFS measurements in conjunction with already published XPS results, a mechanism for the adsorption/absorption of Cu onto sphalerite is proposed. Under conditions of high pH and high nominal surface coverage of the sphalerite by the Cu, Cu(OH) 2 colloidal particles are observed on the sphalerite surfaces using SIMS. Under other conditions, SIMS measurements have indicated that adsorption of the Cu is essentially uniform over the sphalerite surface and is not related to low coordination sites on the surface of the sphalerite. Depth profiling of sphalerite surfaces with Cu adsorbed under conditions that do not result in Cu(OH) 2 colloidal particles show that the Cu adsorbed/absorbed on the sphalerite surface is largely in the first few atomic layers. XAFS analysis of Cu activated sphalerite has indicated that the Cu occupies a distorted trigonal planar geometry, coordinated to three S atoms, in both surface and bulk sites. In addition Cu(1s), absorption edges in XAFS show that both bulk and surface adsorbed copper have an oxidation state less than +1 with the surface Cu being slightly more oxidised than the bulk absorbed Cu. On the basis of the combined XPS, SIMS, XAFS and solution studies, a model is proposed that, on surface adsorption of Cu, the surface Zn(II) atoms are replaced by Cu(II) atoms which are then reduced in situ to Cu(I). This reduction is accompanied by the oxidation of the three neighbouring S atoms to an oxidation state of approximately -1.5. On bulk absorption of Cu atoms into the sphalerite lattice a distorted trigonal planar configuration is achieved through the breakage of a formerly tetrahedral Zn-S bond. The breakage of this bond results in a 3-fold coordinated Cu plus one S 3-fold coordinated to Zn atoms. The breakage of this bond leads to a greater reduction of the Cu than on surface absorption and also oxidation of the 3-fold coordinated S atom to an approximately -0.5 oxidation state. This model does not

  4. Glutathione transferase classes alpha, pi, and mu: GSH activation mechanism.

    PubMed

    Dourado, Daniel F A R; Fernandes, Pedro Alexandrino; Ramos, Maria João

    2010-10-14

    Since the early 1960s, glutathione transferases (GSTs) have been described as detoxification enzymes. In fact, GSTs are the most important enzymes involved in the metabolism of electrophilic xenobiotic/endobiotic compounds. These enzymes are able to catalyze the nucleophilic addition of glutathione (GSH) sulfur thiolate to a wide range of electrophilic substrates, building up a less toxic and more soluble compound. Cytosolic classes alpha, pi, and mu are the most extensively studied GSTs. However, many of the catalytic events are still poorly understood. In the present work, we have resorted to density functional theory (DFT) and to potential of mean force (PMF) calculations to determine the GSH activation mechanism of GSTP1-1 and GSTM1-1 isoenzymes. For the GSTP1-1 enzyme, we have demonstrated that a water molecule, after an initial conformational rearrangement of GSH, can assist a proton transfer between the GSH cysteine thiol (GSH-SH) and the GSH glutamate alpha carboxylate (GSH-COO(-)) groups. The energy barrier associated with the proton transfer is 11.36 kcal·mol(-1). The GSTM1-1 enzyme shows a completely different behavior from the previous isoenzyme. In this case, two water molecules, positioned between the GSH-SH and the ξ N atom of His107, working like a bridge, are able to promote the proton transfer between these two active groups with an energy barrier of 7.98 kcal·mol(-1). All our results are consistent with all the enzymes kinetics and mutagenesis experimental studies.

  5. Mechanical behaviour of metallic thin films on polymeric substrates and the effect of ion beam assistance on crack propagation

    SciTech Connect

    George, M. , E-Mail: matthieu.george@bnfl.com; Coupeau, C.; Colin, J.; Grilhe, J.

    2005-01-10

    The mechanisms of crack propagation in metallic films on polymeric substrates have been studied through in situ atomic force microscopy observations of thin films under tensile stresses and finite element stress calculations. Two series of films - ones deposited with ion beam assistance, the others without - have been investigated. The observations and stress calculations show that ion beam assistance can change drastically the propagation of cracks in coated materials: by improving the adhesion film/substrate, it slows down the delamination process, but in the same time enhances the cracks growth in the thickness of the material.

  6. Proton-Assisted Mechanism of NO Reduction on a Dinuclear Ruthenium Complex.

    PubMed

    Suzuki, Tatsuya; Tanaka, Hiromasa; Shiota, Yoshihito; Sajith, P K; Arikawa, Yasuhiro; Yoshizawa, Kazunari

    2015-08-01

    Density-functional-theory (DFT) calculations are performed for the proposal of a plausible mechanism on the reduction of NO to N2O by a dinuclear ruthenium complex, reported by Arikawa and co-workers [J. Am. Chem. Soc. 2007, 129, 14160]. On the basis of the experimental fact that the reduction proceeds under strongly acidic conditions, the role of protons in the mechanistic pathways is investigated with model complexes, where one or two NO ligands are protonated. The reaction mechanism of the NO reduction is partitioned into three steps: reorientation of N2O2 (cis-NO dimer), O-N bond cleavage, and N2O elimination. A key finding is that the protonation of the NO ligand(s) significantly reduces the activation barrier in the rate-determining reorientation step. The activation energy of 43.1 kcal/mol calculated for the proton-free model is reduced to 30.2 and 17.6 kcal/mol for the mono- and diprotonated models, respectively. The protonation induces the electron transfer from the Ru(II)Ru(II) core to the O═N-N═O moiety to give a Ru(III)Ru(III) core and a hyponitrite (O-N═N-O)(2-) species. The formation of the hyponitrite species provides an alternative pathway for the N2O2 reorientation, resulting in the lower activation energies in the presence of proton(s). The protonation also has a marginal effect on the O-N bond cleavage and the N2O elimination steps. Our calculations reveal a remarkable role of protons in the NO reduction via N2O formation and provide new insights into the mechanism of NO reduction catalyzed by metalloenzymes such as nitric oxide reductase (NOR) that contains a diiron active site. PMID:26186365

  7. Explanation of the mechanism by which CAD assistance improves diagnostic performance when reading CT images

    NASA Astrophysics Data System (ADS)

    Matsumoto, Toru; Wada, Shinichi; Yamamoto, Shinji; Murao, Kohei; Furukawa, Akira; Endo, Masahiro; Matsumoto, Mitsuomi; Sone, Shusuke

    2006-03-01

    The purpose of our research is to make clear the mechanism that a reader (physician or radiological technologist) effectively identify abnormal findings in CT images of lung cancer screening by using with CAD system. A method guessing the 2X2 decision matrix between reader / CAD and reader / reader with CAD was investigated. We suppose the next scene to be it. At first, a reader judges whether abnormal findings per one patient per one CT image are present (1) or absent (0) without CAD results. The second, a reader judges whether abnormal findings are present (1) or absent (0) with CAD results. We expresses the correlation between diagnoses by a reader and CAD system for abnormal cases and for normal cases by following formula using phi correlation coefficient:φ=(cd-ab)/√(a+c)(b+d)(b+c)(a+d). a,b,c,d: 2X2 decision matrix parameters. If TPR1=(a+c)/n, TPR2=(b+c)/n and TPR3=(a+b+c)/n for abnormal cases, TPR3=TPR1+TPR2 - TPR1×TRR2 - φ√TPR1(1-TPR1)TPR2(1-TPR2). Therefore, a=n (TPR3 - TPR1), b=n (TPR3 - TPR2), c=n (TPR1 + TPR2 -TPR3), d=n (1.0 - TPR3). This theory was applied for the experimental data. The 41 students interpreted the same CT images [no training]. A second interpretation was performed after they had been instructed on how to interpret CT images [training], and third was assisted by a virtual CAD [training + CAD]. The mechanism that makes up for a good point of a reader and a CAD with CAD in interpreting CT images was theoretically and experimentally investigated. We concluded that a method guessing the decision matrix (2X2) between a reader and a CAD decided the "presence" or "absence" of abnormal findings explain the improvement mechanism of diagnostic performance with CAD system.

  8. Animal-Assisted Activities for Students with Disabilities: Obtaining Stakeholders' Approval and Planning Strategies for Teachers

    ERIC Educational Resources Information Center

    Baumgartner, Erin; Cho, Jeong-il

    2014-01-01

    Animal-human interactions have been found to have positive influences on children across the world. In particular, research supports the benefits of animal-assisted activities in addressing students' social and behavioral problems within the classroom environment. The general information about animal-assisted activities provided in this…

  9. Effect of cadence regulation on muscle activation patterns during robot assisted gait: a dynamic simulation study.

    PubMed

    Hussain, Shahid; Xie, Sheng Q; Jamwal, Prashant K

    2013-03-01

    Cadence or stride frequency is an important parameter being controlled in gait training of neurologically impaired subjects. The aim of this study was to examine the effects of cadence variation on muscle activation patterns during robot assisted unimpaired gait using dynamic simulations. A twodimensional (2-D) musculoskeletal model of human gait was developed considering eight major muscle groups along with existing ground contact force (GCF) model. A 2-D model of a robotic orthosis was also developed which provides actuation to the hip, knee and ankle joints in the sagittal plane to guide subjects limbs on reference trajectories. A custom inverse dynamics algorithm was used along with a quadratic minimization algorithm to obtain a feasible set of muscle activation patterns. Predicted patterns of muscle activations during slow, natural and fast cadence were compared and the mean muscle activations were found to be increasing with an increase in cadence. The proposed dynamic simulation provide important insight into the muscle activation variations with change in cadence during robot assisted gait and provide the basis for investigating the influence of cadence regulation on neuromuscular parameters of interest during robot assisted gait.

  10. Intracellular mechanisms of lymphoid cell activation.

    PubMed

    Fresa, K; Hameed, M; Cohen, S

    1989-01-01

    Activation of lymphocytes for proliferation is associated with the appearance of an intracellular factor (ADR) that can induce DNA synthesis in isolated quiescent nuclei. ADR plays a role in the sequence of intracellular events leading to activation for IL-2-mediated proliferation. Because of the nature of the defining assay, the locus of ADR action appears to be near the terminal end of the transduction pathway. Interestingly, although lymphocytes from aged individuals respond poorly to proliferative stimuli, they appear to produce normal to above-normal levels of ADR. In contrast, their nuclei are only poorly responsive to stimulation by ADR. Preparations rich in ADR activity have proteolytic activity as well. In addition, aprotinin, as well as a variety of other protease inhibitors, suppresses ADR-induced DNA synthesis in a dose-dependent manner. ADR activity can be removed from active extracts by absorption with aprotinin-conjugated agarose beads, and can be removed from the beads by elution at pH 5.0. This latter suggests that ADR itself is a protease. However, its endogenous substrate is not yet known. We have also detected an inhibitor of ADR activity in the cytoplasm of resting lymphocytes. This is a heat-stable protein of approximately 60,000 Da. In addition to suppressing the interaction of ADR with quiescent nuclei, the inhibitor can suppress DNA synthetic activity of replicative nuclei isolated from mitogen-activated lymphocytes. Interestingly, these preparations had little or no activity on replicative nuclei derived from several neoplastic cell lines. The resistance of tumor cell nuclei to spontaneously occurring cytoplasmic inhibitory factors such as the one described here may provide one explanation for the loss of growth control in neoplastic cells. PMID:2642767

  11. Insights into Mechanism of Glucokinase Activation

    PubMed Central

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

    2012-01-01

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

  12. Universal allosteric mechanism for Gα activation by GPCRs

    PubMed Central

    Flock, Tilman; Venkatakrishnan, A. J.; Kayikci, Melis; Tate, Christopher G.; Veprintsev, Dmitry B.; Babu, M. Madan

    2016-01-01

    G protein-coupled receptors (GPCRs) allosterically activate heterotrimeric G proteins and trigger GDP release. Given that there are ~800 human GPCRs and 16 different Gα proteins, does a universal allosteric mechanism govern Gα activation? Here we show that different GPCRs interact and activate Gα proteins through a highly conserved mechanism. Comparison of Gα with the small G protein Ras reveals how the evolution of short segments that can undergo disorder-order transitions decouple regions important for allosteric activation from receptor binding specificity. This might explain how the GPCR-Gα system diversified rapidly, whilst conserving the allosteric activation mechanism. PMID:26147082

  13. Universal allosteric mechanism for Gα activation by GPCRs.

    PubMed

    Flock, Tilman; Ravarani, Charles N J; Sun, Dawei; Venkatakrishnan, A J; Kayikci, Melis; Tate, Christopher G; Veprintsev, Dmitry B; Babu, M Madan

    2015-08-13

    G protein-coupled receptors (GPCRs) allosterically activate heterotrimeric G proteins and trigger GDP release. Given that there are ∼800 human GPCRs and 16 different Gα genes, this raises the question of whether a universal allosteric mechanism governs Gα activation. Here we show that different GPCRs interact with and activate Gα proteins through a highly conserved mechanism. Comparison of Gα with the small G protein Ras reveals how the evolution of short segments that undergo disorder-to-order transitions can decouple regions important for allosteric activation from receptor binding specificity. This might explain how the GPCR-Gα system diversified rapidly, while conserving the allosteric activation mechanism. PMID:26147082

  14. U.K. physicians' attitudes toward active voluntary euthanasia and physician-assisted suicide.

    PubMed

    Dickinson, George E; Lancaster, Carol J; Clark, David; Ahmedzai, Sam H; Noble, William

    2002-01-01

    A comparison of the views of geriatric medicine physicians and intensive care physicians in the United Kingdom on the topics of active voluntary euthanasia and physician-assisted suicide revealed rather different attitudes. Eighty percent of geriatricians, but only 52% of intensive care physicians, considered active voluntary euthanasia as never justified ethically. Gender and age did not play a major part in attitudinal differences of the respondents. If the variability of attitudes of these two medical specialties are anywhere near illustrative of other physicians in the United Kingdom, it would be difficult to formulate and implement laws and policies concerning euthanasia and assisted suicide. In addition, ample safeguards would be required to receive support from physicians regarding legalization.

  15. Activation Mechanisms in Ion-Implanted Gallium -

    NASA Astrophysics Data System (ADS)

    Morris, Neil

    Available from UMI in association with The British Library. Rapid Thermal Annealing has been used to study the electrical activation of a range of donor and acceptor species in ion-implanted GaAs. By varying the time and temperature of the post implant anneal, it was found that the activation processes for most implants can be characterised in terms of two distinct regions. The first of these occurs at short annealing times, where the electrical activity is seen to follow a time-dependent behaviour. At longer annealing times, however, a time-independent saturation value is reached, this value being dependent on the annealing temperature. By analysing the data from Be, Mg, S and Se implants in GaAs, a comprehensive model has been evolved for the time and temperature dependence of the sheet electrical properties. Application of this model to each of the ions studied suggests that the activation processes may be dominated by the extent to which ions form impurity-vacancy complexes. An analysis of the time-dependent regime also shows that, at short annealing times, the mobile species is more likely to be the substrate atoms (or vacancies) rather than the implanted impurities. In the time-dependent region, the values of diffusion energy were found to be between 2.3 to 3.0 eV for all ions, these values corresponding to a diffusion of Ga or As vacancies (or atoms). In the saturation region, activation energies of 0.3 to 0.4 eV and 1.0 to 1.2 eV were obtained for the activation processes of interstitial or complexed impurities respectively.

  16. Stagnation pressure activated fuel release mechanism for hypersonic projectiles

    DOEpatents

    Cartland, Harry E.; Hunter, John W.

    2003-01-01

    A propulsion-assisted projectile has a body, a cowl forming a combustion section and a nozzle section. The body has a fuel reservoir within a central portion of the body, and a fuel activation system located along the central axis of the body and having a portion of the fuel activation system within the fuel reservoir. The fuel activation system has a fuel release piston with a forward sealing member where the fuel release piston is adapted to be moved when the forward sealing member is impacted with an air flow, and an air-flow channel adapted to conduct ambient air during flight to the fuel release piston.

  17. Home Accidents and Assistance in Daily Activities of Older Women in Turkey

    ERIC Educational Resources Information Center

    Erkal, Sibel; Sahin, Hande

    2010-01-01

    This study analyzed the relation between incidents of at-home accidents and the assistance in daily activities of women age of 65+ living in the area of Dikmen Akpinar Health Care Unit in Ankara-Turkey. Of the women, 49.2% had experienced a home accident in the last 12 months. More than half of these accidents were caused by falling. Women over…

  18. Assisted ambulation and activities for persons with profound multiple disabilities: assessing different ambulation levels.

    PubMed

    Lancioni, G E; Mantini, M; Groeneweg, J

    2001-06-01

    Two participants with profound multiple disabilities were exposed to two occupational situations, which included 1-min. and 3-min. robot-assisted ambulation prior to each activity, respectively. Analysis showed participants' mean percentages of engagement time (session time they spent ambulating or manipulating objects) were well above 90 in both situations. The amount of deviant behavior was somewhat higher in the latter occupational situation for one participant. Implications of the findings were discussed.

  19. Microwave-assisted preparation of azachalcones and their N-alkyl derivatives with antimicrobial activities.

    PubMed

    Usta, Asu; Öztürk, Elif; Beriş, Fatih Ş

    2014-01-01

    Two new azachalcones were prepared by both Claisen-Schmidt condensation and a simple environmentally trendy microwave-assisted method. Ten new N-alkyl (C6,8,10,12,14)-substituted azachalconium bromides (3a-e, 4a-e) were prepared from compounds 1 and 2 with corresponding alkyl halides. The antimicrobial activities of all the compounds were tested against Enterococcus faecalis, Yersinia pseudotuberculosis, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus micro-organisms. PMID:24571646

  20. Novel view on the mechanism of water-assisted proton transfer in the DNA bases: bulk water hydration.

    PubMed

    Furmanchuk, Al'ona; Isayev, Olexandr; Gorb, Leonid; Shishkin, Oleg V; Hovorun, Dmytro M; Leszczynski, Jerzy

    2011-03-14

    In the present work, the conventional static ab initio picture of a water-assisted mechanism of the tautomerization of Nucleic Acid Bases (NABs) in an aqueous environment is enhanced by the classical and Car-Parrinello molecular dynamics simulations. The inclusion of the dynamical contribution is vital because the formation and longevity of the NAB-water bridge complexes represent decisive factors for further tautomerization. The results of both molecular dynamic techniques indicate that the longest time when such complexes exist is significantly shorter than the time required for proton transfer suggested by the static ab initio level of theory. New rate constants of tautomerization corrected for the dynamic effect of environment are proposed based on the first principles molecular dynamics data. Those values are used for the evaluation of a water-assisted mechanism that is feasible in such biological systems as E. coli cell. PMID:21253641

  1. An investigation of cutting mechanics in 2 dimensional ultrasonic vibration assisted milling toward chip thickness and chip formation

    NASA Astrophysics Data System (ADS)

    Rasidi, I. I.; Rafai, N. H.; Rahim, E. A.; Kamaruddin, S. A.; Ding, H.; Cheng, K.

    2015-12-01

    The purpose of this paper is to investigate the effects of 2 dimensional Ultrasonic Vibration Assisted Milling (UVAM) cutting mechanics, considering tool path trajectory and the effect on the chip thickness. The theoretical modelling of cutting mechanics is focused by considering the trajectory of the tool locus into the workpiece during the machining. The studies found the major advantages of VAM are come from the intermittent tool tip interaction phenomena between cutting tool and workpiece. The reduction of thinning chip thickness formations can be identifying advantages from vibration assisted milling in 2 dimensional. The finding will be discussing the comparison between conventional machining the potential of the advantages toward the chip thickness and chip formation in conclusion.

  2. Ultrasonic-Assisted Enzymolysis to Improve the Antioxidant Activities of Peanut (Arachin conarachin L.) Antioxidant Hydrolysate

    PubMed Central

    Yu, Lina; Sun, Jie; Liu, Shaofang; Bi, Jie; Zhang, Chushu; Yang, Qingli

    2012-01-01

    The objective of this work is to provide a theoretical basis for preparing peanut antioxidant hydrolysate in order to improve its antioxidant activities. Therefore, response surface methodology (RSM) based on the Box-Behnken design was used to optimize ultrasonic-assisted enzymolysis for the purpose of preparing peanut antioxidant hydrolysate. Results indicated that the DPPH free radical scavenging activity of peanut hydrolysate could reach 90.06% under the following optimum conditions: ultrasonic power of 150.0 w, reaction temperature of 62.0 °C, incubation time of 25.0 min, and initial pH value of 8.5. The DPPH free radical scavenging rate of peanut hydrolysate from ultrasonic-assisted enzymolysis improved comparing with that of peanut hydrolysate from protease hydrolysis alone. The peanut antioxidant hydrolysate was found to display eight improved kinds of antioxidant activities. In conclusion, the optimal ultrasonic-assisted enzymolysis technology conditions described in this paper, appear to be beneficial for preparing peanut antioxidant hydrolysate. PMID:22942751

  3. Field-assisted synthesis of SERS-active silver nanoparticles using conducting polymers

    NASA Astrophysics Data System (ADS)

    Xu, Ping; Jeon, Sea-Ho; Mack, Nathan H.; Doorn, Stephen K.; Williams, Darrick J.; Han, Xijiang; Wang, Hsing-Lin

    2010-08-01

    A gradient of novel silver nanostructures with widely varying sizes and morphologies is fabricated on a single conducting polyaniline-graphite (P-G) membrane with the assistance of an external electric field. It is believed that the formation of such a silver gradient is a synergetic consequence of the generation of a silver ion concentration gradient along with an electrokinetic flow of silver ions in the field-assisted model, which greatly influences the nucleation and growth mechanism of Ag particles on the P-G membrane. The produced silver dendrites, flowers and microspheres, with sharp edges, intersections and bifurcations, all present strong surface enhanced Raman spectroscopy (SERS) responses toward an organic target molecule, mercaptobenzoic acid (MBA). This facile field-assisted synthesis of Ag nanoparticles via chemical reduction presents an alternative approach to nanomaterial fabrication, which can yield a wide range of unique structures with enhanced optical properties that were previously inaccessible by other synthetic routes.A gradient of novel silver nanostructures with widely varying sizes and morphologies is fabricated on a single conducting polyaniline-graphite (P-G) membrane with the assistance of an external electric field. It is believed that the formation of such a silver gradient is a synergetic consequence of the generation of a silver ion concentration gradient along with an electrokinetic flow of silver ions in the field-assisted model, which greatly influences the nucleation and growth mechanism of Ag particles on the P-G membrane. The produced silver dendrites, flowers and microspheres, with sharp edges, intersections and bifurcations, all present strong surface enhanced Raman spectroscopy (SERS) responses toward an organic target molecule, mercaptobenzoic acid (MBA). This facile field-assisted synthesis of Ag nanoparticles via chemical reduction presents an alternative approach to nanomaterial fabrication, which can yield a wide range

  4. AMPK activators: mechanisms of action and physiological activities.

    PubMed

    Kim, Joungmok; Yang, Goowon; Kim, Yeji; Kim, Jin; Ha, Joohun

    2016-01-01

    AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, which coordinates metabolic pathways and thus balances nutrient supply with energy demand. Because of the favorable physiological outcomes of AMPK activation on metabolism, AMPK has been considered to be an important therapeutic target for controlling human diseases including metabolic syndrome and cancer. Thus, activators of AMPK may have potential as novel therapeutics for these diseases. In this review, we provide a comprehensive summary of both indirect and direct AMPK activators and their modes of action in relation to the structure of AMPK. We discuss the functional differences among isoform-specific AMPK complexes and their significance regarding the development of novel AMPK activators and the potential for combining different AMPK activators in the treatment of human disease. PMID:27034026

  5. AMPK activators: mechanisms of action and physiological activities

    PubMed Central

    Kim, Joungmok; Yang, Goowon; Kim, Yeji; Kim, Jin; Ha, Joohun

    2016-01-01

    AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, which coordinates metabolic pathways and thus balances nutrient supply with energy demand. Because of the favorable physiological outcomes of AMPK activation on metabolism, AMPK has been considered to be an important therapeutic target for controlling human diseases including metabolic syndrome and cancer. Thus, activators of AMPK may have potential as novel therapeutics for these diseases. In this review, we provide a comprehensive summary of both indirect and direct AMPK activators and their modes of action in relation to the structure of AMPK. We discuss the functional differences among isoform-specific AMPK complexes and their significance regarding the development of novel AMPK activators and the potential for combining different AMPK activators in the treatment of human disease. PMID:27034026

  6. [Molecular mechanism at the presynaptic active zone].

    PubMed

    Ohtsuka, Toshihisa

    2011-07-01

    Our higher brain functions such as learning and memory, emotion, and consciousness depend on the precise regulation of complicated neural networks in the brain. Neurons communicate with each other through the synapse, which comprise 3 regions: the presynapse, synaptic cleft, and postsynapse. The active zone (AZ) beneath the presynaptic membrane is the principal site for Ca2+ -dependent neurotransmitter release: AZ is involved in determining the site for docking and synaptic vesicle fusion. Presently, the full molecular composition of AZ is unclear, but it is known to contain several AZ-specific proteins, including cytomatrix of the active zone-associated protein (CAST)/ERC2, ELKS, RIM1, Munc13-1, Piccolo/Aczonin, and Bassoon. CAST and ELKS are novel active zone proteins that directly bind to Rab3-interacting molecules (RIMs), Bassoon, and Piccolo, and are thought to play a role in neurotransmitter release by binding these to AZ proteins. In this review, current advances in studies on AZ structure and function have been summarized, and the focus is mainly on protein-protein interactions among the AZ proteins.

  7. Biomolecule-assisted synthesis of single-crystalline selenium nanowires and nanoribbons via a novel flake-cracking mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Ye, Xingchen; Dai, Wei; Hou, Weiyi; Zuo, Fan; Xie, Yi

    2006-01-01

    Recently, the biomolecule-assisted synthesis method has been a new and promising focus in the preparation of various nanomaterials. But current works mainly focus on the synthesis of metal nanoparticles and nanowires using macro-biomolecules (e.g. virus, protein and DNA) as templates in the presence of a reducing agent. Beta-carotene, one of the most common bio-antioxidants, can be oxidized to form species with both hydrophilic and hydrophobic ends, which can provide an in situ soft template for the synthesis of nanomaterials. Herein, a simple beta-carotene-assisted method was developed for the first time to synthesize t-Se nanowires and nanoribbons with high crystallinity. We demonstrate that beta-carotene serves as not only the reducing agent, but also an in situ template in the preparation of Se one-dimensional nanostructures. It is found that the growth mechanism of Se nanomaterials is different from the familiar sphere-wire process. A novel flake-cracking mechanism is proposed. By this biomolecule-assisted route, Te one-dimensional nanostructures and Pd nanowires were also fabricated. The assisted-biomolecule in our method may be spread to carotenoids and other antioxidants, and thus broaden the application fields of biomolecules. Our preliminary investigations have shown that the facile, solution-phase biomolecule-assisted method can be potentially extended to the preparation of other low-dimensional nanostructures. The synthesized t-Se nanowires and nanoribbons may serve as templates to generate other tubular functional nanomaterials and find applications in the studies of structure-property relationships as well as in the fabrication of nanoscale optoelectronic devices.

  8. Mechanism for Clastogenic Activity of Naphthalene

    SciTech Connect

    Buchholz, Bruce A.

    2015-09-29

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

  9. Experimental investigation on the mechanism of chelation-assisted, copper(II) acetate-accelerated azide-alkyne cycloaddition.

    PubMed

    Kuang, Gui-Chao; Guha, Pampa M; Brotherton, Wendy S; Simmons, J Tyler; Stankee, Lisa A; Nguyen, Brian T; Clark, Ronald J; Zhu, Lei

    2011-09-01

    A mechanistic model is formulated to account for the high reactivity of chelating azides (organic azides capable of chelation-assisted metal coordination at the alkylated azido nitrogen position) and copper(II) acetate (Cu(OAc)(2)) in copper(II)-mediated azide-alkyne cycloaddition (AAC) reactions. Fluorescence and (1)H NMR assays are developed for monitoring the reaction progress in two different solvents, methanol and acetonitrile. Solvent kinetic isotopic effect and premixing experiments give credence to the proposed different induction reactions for converting copper(II) to catalytic copper(I) species in methanol (methanol oxidation) and acetonitrile (alkyne oxidative homocoupling), respectively. The kinetic orders of individual components in a chelation-assisted, copper(II)-accelerated AAC reaction are determined in both methanol and acetonitrile. Key conclusions resulting from the kinetic studies include (1) the interaction between copper ion (either in +1 or +2 oxidation state) and a chelating azide occurs in a fast, pre-equilibrium step prior to the formation of the in-cycle copper(I)-acetylide, (2) alkyne deprotonation is involved in several kinetically significant steps, and (3) consistent with prior experimental and computational results by other groups, two copper centers are involved in the catalysis. The X-ray crystal structures of chelating azides with Cu(OAc)(2) suggest a mechanistic synergy between alkyne oxidative homocoupling and copper(II)-accelerated AAC reactions, in which both a bimetallic catalytic pathway and a base are involved. The different roles of the two copper centers (a Lewis acid to enhance the electrophilicity of the azido group and a two-electron reducing agent in oxidative metallacycle formation, respectively) in the proposed catalytic cycle suggest that a mixed valency (+2 and +1) dinuclear copper species be a highly efficient catalyst. This proposition is supported by the higher activity of the partially reduced Cu(OAc)(2) in

  10. Mechanism of antibacterial activity of copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Chatterjee, Arijit Kumar; Chakraborty, Ruchira; Basu, Tarakdas

    2014-04-01

    In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu2+ ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously.

  11. Mechanism of antibacterial activity of copper nanoparticles.

    PubMed

    Chatterjee, Arijit Kumar; Chakraborty, Ruchira; Basu, Tarakdas

    2014-04-01

    In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu(2+) ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously. PMID:24584282

  12. The Effect of Active Student Responding during Computer-Assisted Instruction on Social Studies Learning by Students with Learning Disabilities

    ERIC Educational Resources Information Center

    Jerome, Annamaria; Barbetta, Patricia M.

    2005-01-01

    An alternating treatments design with a best treatments phase was used to compare two active student response (ASR) conditions and one on-task (OT) condition on the acquisition and maintenance of social studies facts during computer-assisted instruction. Each week for six weeks, five students were provided daily computer-assisted instruction on 21…

  13. A Profile of Adults Needing Assistance with Activities of Daily Living, 1991-1992. Disability Statistics Report 11.

    ERIC Educational Resources Information Center

    Kennedy, Jae; LaPlante, Mitchell P.

    This report uses data from the 1990 and 1991 samples of the Survey of Income and Program Participation to construct a profile of the U.S. noninstitutionalized adult population needing assistance with activities of daily living (ADL) and to estimate the size of the population eligible for federal personal assistance services (PAS) under different…

  14. Synthesis of nanostructured and microstructured ZnO and Zn(OH)2 on activated carbon cloth by hydrothermal and microwave-assisted chemical bath deposition methods

    NASA Astrophysics Data System (ADS)

    Mosayebi, Elham; Azizian, Saeid; Hajian, Ali

    2015-05-01

    Nanostructured and microstructured ZnO and Zn(OH)2 loaded on activated carbon cloth were synthesized by microwave-assisted chemical bath deposition and hydrothermal methods. By hydrothermal method the deposited sample on carbon fiber is pure ZnO with dandelion-like nanostructures. By microwave-assisted chemical bath method the structure and composition of deposited sample depends on solution pH. At pH = 9.8 the deposited sample on carbon fiber is pure ZnO with flower-like microstructure; but at pH = 10.8 the sample is a mixture of ZnO and Zn(OH)2 with flower-like and rhombic microstructures, respectively. The mechanism of crystal grow by microwave-assisted chemical bath method was investigated by SEM method at both pH.

  15. Mechanism of aneurysm formation after 830-nm diode-laser-assisted microarterial anastomosis

    NASA Astrophysics Data System (ADS)

    Tang, Jing; Godlewski, Guilhem; Rouy, Simone

    1998-01-01

    A series of 830 nm diode laser assisted longitudinal aortorrhophy with a condition of 400 to 500 J/mm2 for one cm length of anastomosis versus conventional manual anastomoses were performed in 90 Wistar rats. With comparing with normal media process, a histologic examination of aneurysm formation was conducted. The results show that there are two important factors to cause aneurysm formation after laser assisted anastomosis: (1) vessel wall is damaged by laser heating; (2) proliferation of collagen fiber at adventitia is absent when media reconstruction.

  16. A biomimetic pathway for vanadium-catalyzed aerobic oxidation of alcohols: evidence for a base-assisted dehydrogenation mechanism.

    PubMed

    Wigington, Bethany N; Drummond, Michael L; Cundari, Thomas R; Thorn, David L; Hanson, Susan K; Scott, Susannah L

    2012-11-19

    The first step in the catalytic oxidation of alcohols by molecular O(2), mediated by homogeneous vanadium(V) complexes [LV(V)(O)(OR)], is ligand exchange. The unusual mechanism of the subsequent intramolecular oxidation of benzyl alcoholate ligands in the 8-hydroxyquinolinato (HQ) complexes [(HQ)(2)V(V)(O)(OCH(2)C(6)H(4)-p-X)] involves intermolecular deprotonation. In the presence of triethylamine, complex 3 (X = H) reacts within an hour at room temperature to generate, quantitatively, [(HQ)(2)V(IV)(O)], benzaldehyde (0.5 equivalents), and benzyl alcohol (0.5 equivalents). The base plays a key role in the reaction: in its absence, less than 12% conversion was observed after 72 hours. The reaction is first order in both 3 and NEt(3), with activation parameters ΔH(≠)=(28±4) kJ mol(-1) and ΔS(≠)=(-169±4) J K(-1)  mol(-1). A large kinetic isotope effect, 10.2±0.6, was observed when the benzylic hydrogen atoms were replaced by deuterium atoms. The effect of the para substituent of the benzyl alcoholate ligand on the reaction rate was investigated using a Hammett plot, which was constructed using σ(p). From the slope of the Hammett plot, ρ=+(1.34±0.18), a significant buildup of negative charge on the benzylic carbon atom in the transition state is inferred. These experimental findings, in combination with computational studies, support an unusual bimolecular pathway for the intramolecular redox reaction, in which the rate-limiting step is deprotonation at the benzylic position. This mechanism, that is, base-assisted dehydrogenation (BAD), represents a biomimetic pathway for transition-metal-mediated alcohol oxidations, differing from the previously identified hydride-transfer and radical pathways. It suggests a new way to enhance the activity and selectivity of vanadium catalysts in a wide range of redox reactions, through control of the outer coordination sphere. PMID:23080554

  17. Providing training and technical assistance to customs officers and border guards: An effective mechanism to improve export controls

    SciTech Connect

    Gritton, C.A.

    1995-12-31

    With the disintegration of the Soviet Union, an increasing international concern requiring attention is illegal trafficking in nuclear and nuclear-related dual-use commodities. For the past few years, the US government, including the Department of Energy (DOE), has assisted the former Soviet Union in establishing and enhancing national export control systems. Although US assistance has been targeted to help control approved transfers, part of the focus has shifted to prevent the illegal exit of special nuclear material, dual-use items, and other nuclear-related materials. As part of a State Department initiative, a Nonproliferation and Disarmament Fund (NDF) was established to address various nonproliferation concerns. One project, funded by NDF, US Customs Service (Customs), and the DOE, focuses on assisting transit countries to prevent illegal trafficking. DOE is providing technical expertise to seven countries in the Baltics and Central Europe to help identify materials, equipment, and technology that might transit their borders. Although there are many mechanisms to prevent illegal trafficking, this paper will discuss the importance of providing international customs officials and border guards with training and technical assistance on nuclear materials and nuclear-related dual-use items. More specifically, detail of the DOE training plan will be discussed.

  18. Field-Activated, Pressure-Assisted Synthesis of Ultra-hard, Super-Abrasive AlMgB14

    NASA Astrophysics Data System (ADS)

    Liu, Wen; Wu, Yin-tao; Mao, Shu-hong; Pan, Rui-li; Zhang, Jing; Zhang, Tie-ming

    2013-04-01

    Mechanical alloying (MA) and the field-activated and pressure-assisted in situ synthesis (FAPAS) were combined to prepare the ultra-hard and super-abrasive AlMgB14 with the characteristics of fast heating-up, high efficiency, and low energy cost. Such preparations using the elemental constituents, such as Al, Mg, and B, were performed at a vacuum annealed temperature of 1500 °C under a pressure of 60 MPa. The resultant ceramics were characterized by SEM, EDS, and XRD. It was shown that the samples contained uniform AlMgB14, and the maximum hardness on the sample surface may reach 32.5 GPa. Furthermore, a second experiment was performed, in which MgH2 was used as one of the starting materials instead of elemental Mg, but this approach did not produce AlMgB14.

  19. [Ventricular assist device – Possibilities of long-term mechanical circulatory support].

    PubMed

    Englberger, Lars; Reineke, David C; Martinelli, Michele V; Mohacsi, Paul; Carrel, Thierry P

    2015-08-01

    In Switzerland 200’000 people suffer from congestive heart failure. Approximately 10’000 patients find themselves in an advanced state of the disease. When conservative treatment options are no longer available heart transplantation is the therapy of choice. Should this not be an option due to long waiting lists or medical issues assist device therapy becomes an option. Assist device therapy is separated in short-term and long-term support. Long-term support is nowadays performed with ventricular assist devices (VADs). The native heart is still in place and supported in parallel to the remaining function of the heart. The majority of patients are treated with a left ventricular assist device (LVAD). The right ventrical alone (RVAD) as well as bi-ventricular support (BiVAD) is rarely needed. The modern VADs are implantable and create a non-pulsative bloodflow. A percutaneous driveline enables energy supply and pump-control. Indication strategies for VAD implantations include bridge to transplant (short term support), bridge to candidacy and bridge to transplant. VADs become more and more a definite therapeutic option (destination therapy). VAD therapy might be a realistic alternative to organ transplantation in the near future. PMID:26227978

  20. Cellulase-assisted extraction and antioxidant activity of the polysaccharides from garlic.

    PubMed

    Pan, Saikun; Wu, Shengjun

    2014-10-13

    In the present study, the polysaccharides were prepared from garlic by using a cellulase-assisted extraction method and the antioxidant activity of garlic polysaccharides (GPs) was evaluated. To improve the yield of GPs, the influences of the several factors such as extraction time, temperature, pH, and cellulase amount on the extraction efficiency were studied. The optimal conditions for extraction of GPs were determined as follows: time, 80 min; temperature, 45 °C; pH, 5; cellulase amount, 8000 U/g. Under the optimised extraction conditions, the yield of GPS reached up to 35.34%. The GPs product exhibited strong antioxidant activity including hydroxyl radical scavenging activity, 2,2-diphenyl-β-picrylhydrazyl radical scavenging activity, and reducing power. The results suggest that the GPs could be used as potential antioxidants.

  1. Gamma Band Activity in the RAS-intracellular mechanisms

    PubMed Central

    Garcia-Rill, E.; Kezunovic, N.; D’Onofrio, S.; Luster, B.; Hyde, J.; Bisagno, V.; Urbano, F.J.

    2014-01-01

    Gamma band activity participates in sensory perception, problem solving, and memory. This review considers recent evidence showing that cells in the reticular activating system (RAS) exhibit gamma band activity, and describes the intrinsic membrane properties behind such manifestation. Specifically, we discuss how cells in the mesopontine pedunculopontine nucleus (PPN), intralaminar parafascicular nucleus (Pf), and pontine Subcoeruleus nucleus dorsalis (SubCD) all fire in the gamma band range when maximally activated, but no higher. The mechanisms involve high threshold, voltage-dependent P/Q-type calcium channels or sodium-dependent subthreshold oscillations. Rather than participating in the temporal binding of sensory events as in the cortex, gamma band activity in the RAS may participate in the processes of preconscious awareness, and provide the essential stream of information for the formulation of many of our actions. We address three necessary next steps resulting from these discoveries, an intracellular mechanism responsible for maintaining gamma band activity based on persistent G-protein activation, separate intracellular pathways that differentiate between gamma band activity during waking vs during REM sleep, and an intracellular mechanism responsible for the dysregulation in gamma band activity in schizophrenia. These findings open several promising research avenues that have not been thoroughly explored. What are the effects of sleep or REM sleep deprivation on these RAS mechanisms? Are these mechanisms involved in memory processing during waking and/or during REM sleep? Does gamma band processing differ during waking vs REM sleep after sleep or REM sleep deprivation? PMID:24309750

  2. Robot-assisted motor activation monitored by time-domain optical brain imaging

    NASA Astrophysics Data System (ADS)

    Steinkellner, O.; Wabnitz, H.; Schmid, S.; Steingräber, R.; Schmidt, H.; Krüger, J.; Macdonald, R.

    2011-07-01

    Robot-assisted motor rehabilitation proved to be an effective supplement to conventional hand-to-hand therapy in stroke patients. In order to analyze and understand motor learning and performance during rehabilitation it is desirable to develop a monitor to provide objective measures of the corresponding brain activity at the rehabilitation progress. We used a portable time-domain near-infrared reflectometer to monitor the hemodynamic brain response to distal upper extremity activities. Four healthy volunteers performed two different robot-assisted wrist/forearm movements, flexion-extension and pronation-supination in comparison with an unassisted squeeze ball exercise. A special headgear with four optical measurement positions to include parts of the pre- and postcentral gyrus provided a good overlap with the expected activation areas. Data analysis based on variance of time-of-flight distributions of photons through tissue was chosen to provide a suitable representation of intracerebral signals. In all subjects several of the four detection channels showed a response. In some cases indications were found of differences in localization of the activated areas for the various tasks.

  3. Mechanisms to enhance the effectiveness of allied health and social care assistants in community-based rehabilitation services: a qualitative study.

    PubMed

    Moran, Anna; Nancarrow, Susan A; Enderby, Pamela

    2015-07-01

    This research aims to describe the factors associated with successful employment of allied health and social care assistants in community-based rehabilitation services (CBRS) in England. The research involved the thematic analysis of interviews and focus groups with 153 professionally qualified and assistant staff from 11 older people's interdisciplinary community rehabilitation teams. Data were collected between November 2006 and December 2008. Assistants were perceived as a focal point for care delivery and conduits for enabling a service to achieve goals within interdisciplinary team structures. Nine mechanisms were identified that promoted the successful employment of assistants: (i) Multidisciplinary team input into assistant training and support; (ii) Ensuring the timely assessment of clients by qualified staff; (iii) Establishing clear communication structures between qualified and assistant staff; (iv) Co-location of teams to promote communication and skill sharing; (v) Removing barriers that prevent staff working to their full scope of practice; (vi) Facilitating role flexibility of assistants, while upholding the principles of reablement; (vii) Allowing sufficient time for client-staff interaction; (viii) Ensuring an appropriate ratio of assistant to qualified staff to enable sufficient training and supervision of assistants; and (ix) Appropriately, resourcing the role for training and reimbursement to reflect responsibility. We conclude that upholding these mechanisms may help to optimise the efficiency and productivity of assistant and professionally qualified staff in CBRS.

  4. A system for delivering mechanical stimulation and robot-assisted therapy to the rat whisker pad during facial nerve regeneration.

    PubMed

    Heaton, James T; Knox, Christopher J; Malo, Juan S; Kobler, James B; Hadlock, Tessa A

    2013-11-01

    Functional recovery is typically poor after facial nerve transection and surgical repair. In rats, whisking amplitude remains greatly diminished after facial nerve regeneration, but can recover more completely if the whiskers are periodically mechanically stimulated during recovery. Here we present a robotic "whisk assist" system for mechanically driving whisker movement after facial nerve injury. Movement patterns were either preprogrammed to reflect natural amplitudes and frequencies, or movements of the contralateral (healthy) side of the face were detected and used to control real-time mirror-like motion on the denervated side. In a pilot study, 20 rats were divided into nine groups and administered one of eight different whisk assist driving patterns (or control) for 5-20 minutes, five days per week, across eight weeks of recovery after unilateral facial nerve cut and suture repair. All rats tolerated the mechanical stimulation well. Seven of the eight treatment groups recovered average whisking amplitudes that exceeded controls, although small group sizes precluded statistical confirmation of group differences. The potential to substantially improve facial nerve recovery through mechanical stimulation has important clinical implications, and we have developed a system to control the pattern and dose of stimulation in the rat facial nerve model.

  5. Mechanical Activation of Construction Binder Materials by Various Mills

    NASA Astrophysics Data System (ADS)

    Fediuk, R. S.

    2016-04-01

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

  6. A Study of a Handrim-Activated Power-Assist Wheelchair Based on a Non-Contact Torque Sensor

    PubMed Central

    Nam, Ki-Tae; Jang, Dae-Jin; Kim, Yong Chol; Heo, Yoon; Hong, Eung-Pyo

    2016-01-01

    Demand for wheelchairs is increasing with growing numbers of aged and disabled persons. Manual wheelchairs are the most commonly used assistive device for mobility because they are convenient to transport. Manual wheelchairs have several advantages but are not easy to use for the elderly or those who lack muscular strength. Therefore, handrim-activated power-assist wheelchairs (HAPAW) that can aid driving power with a motor by detecting user driving intentions through the handrim are being researched. This research will be on HAPAW that judge user driving intentions by using non-contact torque sensors. To deliver the desired motion, which is sensed from handrim rotation relative to a fixed controller, a new driving wheel mechanism is designed by applying a non-contact torque sensor, and corresponding torques are simulated. Torques are measured by a driving wheel prototype and compared with simulation results. The HAPAW prototype was developed using the wheels and a driving control algorithm that uses left and right input torques and time differences are used to check if the non-contact torque sensor can distinguish users’ driving intentions. Through this procedure, it was confirmed that the proposed sensor can be used effectively in HAPAW. PMID:27509508

  7. A Study of a Handrim-Activated Power-Assist Wheelchair Based on a Non-Contact Torque Sensor.

    PubMed

    Nam, Ki-Tae; Jang, Dae-Jin; Kim, Yong Chol; Heo, Yoon; Hong, Eung-Pyo

    2016-01-01

    Demand for wheelchairs is increasing with growing numbers of aged and disabled persons. Manual wheelchairs are the most commonly used assistive device for mobility because they are convenient to transport. Manual wheelchairs have several advantages but are not easy to use for the elderly or those who lack muscular strength. Therefore, handrim-activated power-assist wheelchairs (HAPAW) that can aid driving power with a motor by detecting user driving intentions through the handrim are being researched. This research will be on HAPAW that judge user driving intentions by using non-contact torque sensors. To deliver the desired motion, which is sensed from handrim rotation relative to a fixed controller, a new driving wheel mechanism is designed by applying a non-contact torque sensor, and corresponding torques are simulated. Torques are measured by a driving wheel prototype and compared with simulation results. The HAPAW prototype was developed using the wheels and a driving control algorithm that uses left and right input torques and time differences are used to check if the non-contact torque sensor can distinguish users' driving intentions. Through this procedure, it was confirmed that the proposed sensor can be used effectively in HAPAW. PMID:27509508

  8. Combined feedforward and model-assisted active disturbance rejection control for non-minimum phase system.

    PubMed

    Sun, Li; Li, Donghai; Gao, Zhiqiang; Yang, Zhao; Zhao, Shen

    2016-09-01

    Control of the non-minimum phase (NMP) system is challenging, especially in the presence of modelling uncertainties and external disturbances. To this end, this paper presents a combined feedforward and model-assisted Active Disturbance Rejection Control (MADRC) strategy. Based on the nominal model, the feedforward controller is used to produce a tracking performance that has minimum settling time subject to a prescribed undershoot constraint. On the other hand, the unknown disturbances and uncertain dynamics beyond the nominal model are compensated by MADRC. Since the conventional Extended State Observer (ESO) is not suitable for the NMP system, a model-assisted ESO (MESO) is proposed based on the nominal observable canonical form. The convergence of MESO is proved in time domain. The stability, steady-state characteristics and robustness of the closed-loop system are analyzed in frequency domain. The proposed strategy has only one tuning parameter, i.e., the bandwidth of MESO, which can be readily determined with a prescribed robustness level. Some comparative examples are given to show the efficacy of the proposed method. This paper depicts a promising prospect of the model-assisted ADRC in dealing with complex systems. PMID:27167989

  9. Activation Mechanism of the Bacteroides fragilis Cysteine Peptidase, Fragipain.

    PubMed

    Herrou, Julien; Choi, Vivian M; Bubeck Wardenburg, Juliane; Crosson, Sean

    2016-07-26

    Enterotoxigenic Bacteroides fragilis produces a secreted metalloprotease known as B. fragilis toxin (BFT), which contributes to anaerobic sepsis, colitis, and colonic malignancy in mouse models of disease. A C11 family cysteine protease, fragipain (Fpn), directly activates BFT in the B. fragilis cell by removing the BFT prodomain. Fpn is itself a proenzyme and is autoactivated upon cleavage at an arginine residue in its activation loop. We have defined the proteolytic active site of Fpn, demonstrated that Fpn autoactivation can occur by an in trans loop cleavage mechanism, and characterized structural features of the Fpn activation loop that control peptidase activity against several substrates, including BFT. An arginine residue at the autocleavage site determines the fast activation kinetics of Fpn relative to the homologous C11 protease, PmC11, which is cleaved at lysine. Arginine to alanine substitution at the cleavage site ablated peptidase activity, as did partial truncation of the Fpn activation loop. However, complete truncation of the activation loop yielded an uncleaved, pro form of Fpn that was active as a peptidase against both Fpn and BFT substrates. Thus, Fpn can be transformed into an active peptidase in the absence of activation loop cleavage. This study provides insight into the mechanism of fragipain activation and, more generally, defines the role of the C11 activation loop in the control of peptidase activity and substrate specificity.

  10. Fracture mechanics and surface chemistry investigations of environment-assisted crack growth

    NASA Technical Reports Server (NTRS)

    Wei, R. P.; Klier, K.; Simmons, G. W.; Chou, Y. T.

    1984-01-01

    It is pointed out that environment-assisted subcritical crack growth in high-strength steels and other high-strength alloys (particularly in hydrogen and in hydrogenous environments) is an important technological problem of long standing. This problem is directly related to issues of structural integrity, durability, and reliability. The terms 'hydrogen embrittlement' and 'stress corrosion cracking' have been employed to describe the considered phenomenon. This paper provides a summary of contributions made during the past ten years toward the understanding of environmentally assisted crack growth. The processes involved in crack growth are examined, and details regarding crack growth and chemical reactions are discussed, taking into account crack growth in steels exposed to water/water vapor, the effect of hydrogen, reactions involving hydrogen sulfide, and aspects of fracture surface morphology and composition. Attention is also given to the modeling of crack growth response, crack growth in gas mixtures, and the interaction of solute atoms with the crack-tip stress field.

  11. Mechanisms underlying regulation of the expression and activities of the mammalian pyruvate dehydrogenase kinases.

    PubMed

    Sugden, Mary C; Holness, Mark J

    2006-07-01

    The mechanisms that control mammalian pyruvate dehydrogenase complex (PDC) activity include its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDKs 1 - 4). Here we review new developments in the regulation of the activities and expression of the PDKs, in particular PDK2 and PDK4, in relation to glucose and lipid homeostasis. This review describes recent advances relating to the acute and long-term modes of regulation of the PDKs, with particular emphasis on the regulatory roles of nuclear receptors including peroxisome proliferator-activated receptor (PPAR) alpha and Liver X receptor (LXR), PPAR gamma coactivator alpha (PGC-1alpha) and insulin, and the impact of changes in PDK activity and expression in glucose and lipid homeostasis. Since PDK4 may assist in lipid clearance when there is an imbalance between lipid delivery and oxidation, it may represent an attractive target for interventions aimed at rectifying abnormal lipid as well as glucose homeostasis in disease states. PMID:17132539

  12. Recognition of user's activity for adaptive cooperative assistance in robotic surgery.

    PubMed

    Nessi, Federico; Beretta, Elisa; Ferrigno, Giancarlo; De Momi, Elena

    2015-01-01

    During hands-on robotic surgery it is advisable to know how and when to provide the surgeon with different assistance levels with respect to the current performed activity. Gesteme-based on-line classification requires the definition of a complete set of primitives and the observation of large signal percentage. In this work an on-line, gesteme-free activity recognition method is addressed. The algorithm models the guidance forces and the resulting trajectory of the manipulator with 26 low-level components of a Gaussian Mixture Model (GMM). Temporal switching among the components is modeled with a Hidden Markov Model (HMM). Tests are performed in a simplified scenario over a pool of 5 non-surgeon users. Classification accuracy resulted higher than 89% after the observation of a 300 ms-long signal. Future work will address the use of the current detected activity to on-line trigger different strategies to control the manipulator and adapt the level of assistance. PMID:26737482

  13. Microwave-assisted extraction of polysaccharides from Yupingfeng powder and their antioxidant activity

    PubMed Central

    Wang, Dan; Zhang, Bi-Bo; Qu, Xiao-Xia; Gao, Feng; Yuan, Min-Yong

    2015-01-01

    Background: Microwave-assisted reflux extraction of polysaccharides YPF-P from the famous Chinese traditional drug, Yupingfeng powder, optimization of extracting conditions and evaluation of their antioxidant activity were conducted in this study. Results: Single factor effect trends were achieved through yields and contends of YPF-P obtained from different extracting conditions. Then through a three-level, four-variable Box-Behnken design of response surface methodology adopting yield as response, the optimal conditions were determined as follows: Material/solvent ratio 1:23.37, microwave power 560 W, Extraction temperature 64°C, and extraction time 9.62 min. Under the optimal conditions, the YPF-P extraction yield was 3.23%, and its content was detected as 38.52%. In antioxidant assays, the YPF-P was tested to possess 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities with an IC50 value of 0.262 mg/ml. In addition, YPF-P was also proved to have relatively low ferric reducing antioxidant power (FRAP), compared to Vc, through FRAP assay. Conclusion: In the microwave assisted reflux extraction research, good YPF-P yield was achieved from materials with relatively low YPF-P content. And for the first time, both DPPH and FRAP assays were conducted on YPF-P, which proved that the antioxidant activity of YPF-P contributed to the functions of this medicine. PMID:26246730

  14. Water-plasma-assisted synthesis of black titania spheres with efficient visible-light photocatalytic activity.

    PubMed

    Panomsuwan, Gasidit; Watthanaphanit, Anyarat; Ishizaki, Takahiro; Saito, Nagahiro

    2015-06-01

    Black titania spheres (H-TiO2-x) were synthesized via a simple green method assisted by water plasma at a low temperature and atmospheric pressure. The in situ production of highly energetic hydroxyl and hydrogen species from water plasma are the prominent factors in the oxidation and hydrogenation reactions during the formation of H-TiO2-x, respectively. The visible-light photocatalytic activity toward the dye degradation of H-TiO2-x can be attributed to the synergistic effect of large-surface area, visible-light absorption and the existence of oxygen vacancies and Ti(3+) sites. PMID:25946395

  15. User-centric design of a personal assistance robot (FRASIER) for active aging.

    PubMed

    Padir, Taşkin; Skorinko, Jeanine; Dimitrov, Velin

    2015-01-01

    We present our preliminary results from the design process for developing the Worcester Polytechnic Institute's personal assistance robot, FRASIER, as an intelligent service robot for enabling active aging. The robot capabilities include vision-based object detection, tracking the user and help with carrying heavy items such as grocery bags or cafeteria trays. This work-in-progress report outlines our motivation and approach to developing the next generation of service robots for the elderly. Our main contribution in this paper is the development of a set of specifications based on the adopted user-centered design process, and realization of the prototype system designed to meet these specifications. PMID:26737419

  16. Water-plasma-assisted synthesis of black titania spheres with efficient visible-light photocatalytic activity.

    PubMed

    Panomsuwan, Gasidit; Watthanaphanit, Anyarat; Ishizaki, Takahiro; Saito, Nagahiro

    2015-06-01

    Black titania spheres (H-TiO2-x) were synthesized via a simple green method assisted by water plasma at a low temperature and atmospheric pressure. The in situ production of highly energetic hydroxyl and hydrogen species from water plasma are the prominent factors in the oxidation and hydrogenation reactions during the formation of H-TiO2-x, respectively. The visible-light photocatalytic activity toward the dye degradation of H-TiO2-x can be attributed to the synergistic effect of large-surface area, visible-light absorption and the existence of oxygen vacancies and Ti(3+) sites.

  17. User-centric design of a personal assistance robot (FRASIER) for active aging.

    PubMed

    Padir, Taşkin; Skorinko, Jeanine; Dimitrov, Velin

    2015-01-01

    We present our preliminary results from the design process for developing the Worcester Polytechnic Institute's personal assistance robot, FRASIER, as an intelligent service robot for enabling active aging. The robot capabilities include vision-based object detection, tracking the user and help with carrying heavy items such as grocery bags or cafeteria trays. This work-in-progress report outlines our motivation and approach to developing the next generation of service robots for the elderly. Our main contribution in this paper is the development of a set of specifications based on the adopted user-centered design process, and realization of the prototype system designed to meet these specifications.

  18. Health-Promoting Physical Activity of Children Who Use Assistive Mobility Devices: A Scoping Review.

    PubMed

    Jirikowic, Tracy L; Kerfeld, Cheryl I

    2016-01-01

    Children with physical disabilities who use assistive mobility devices (AMDs) are at risk for obesity and other secondary health conditions. Habitual physical activity is one lifestyle factor that may prevent obesity and contribute to overall health, and an active lifestyle in childhood improves prospects for lifelong healthy behaviors. Child, family, and environmental facilitators and barriers influence health-promoting physical activity (HPPA) for children without disabilities, but comparable models and levels of understanding for children who use AMDs are lacking. In this scoping review, we identified a similar set of child, family, and environmental facilitators and barriers relevant to HPPA participation among children who use AMDs. Noted gaps in the literature included limited reporting of AMD use, inconsistent HPPA definitions, and inadequate measurement tools for children who are nonambulatory. The identified child, family, and environmental factors provide a framework for occupational therapy practitioners and interprofessional teams to develop HPPA opportunities and interventions for an underserved population. PMID:27548861

  19. Anthocyanidins inhibit activator protein 1 activity and cell transformation: structure-activity relationship and molecular mechanisms.

    PubMed

    Hou, De-Xing; Kai, Keiko; Li, Jian-Jian; Lin, Shigang; Terahara, Norihiko; Wakamatsu, Mika; Fujii, Makoto; Young, Mattew R; Colburn, Nancy

    2004-01-01

    Anthocyanins are the chemical components that give the intense color to many fruits and vegetables, such as blueberries, red cabbages and purple sweet potatoes. Extensive studies have indicated that anthocyanins have strong antioxidant activities. To investigate the mechanism of anthocyanidins as an anticancer food source, six kinds of anthocyanidins representing the aglycons of most anthocyanins, were used to examine their effects on tumor promotion in mouse JB6 cells, a validated model for screening cancer chemopreventive agents and elucidating the molecular mechanisms. Of the six anthocyanins tested, only those with an ortho-dihydroxyphenyl structure on the B-ring suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation and activator protein-1 transactivation, suggesting that the ortho-dihydroxyphenyl may contribute to the inhibitory action. Delphinidin, but not peonidin, blocked the phosphorylation of protein kinases in the extracellular signal-regulated protein kinase (ERK) pathway at early times and the c-Jun N-terminal kinase (JNK) signaling pathway at later times. p38 kinase was not inhibited by delphinidin. Furthermore, two mitogen-activated protein kinase (MAPK) specific inhibitors (SP600125 for JNK and UO126 for ERK) could specifically block the activation of JNK and ERK and cell transformation. Those results demonstrate that anthocyanidins contribute to the inhibition of tumorigenesis by blocking activation of the MAPK pathway. These findings provide the first molecular basis for the anticarcinogenic action of anthocyanidins. PMID:14514663

  20. Anthocyanidins inhibit activator protein 1 activity and cell transformation: structure-activity relationship and molecular mechanisms.

    PubMed

    Hou, De-Xing; Kai, Keiko; Li, Jian-Jian; Lin, Shigang; Terahara, Norihiko; Wakamatsu, Mika; Fujii, Makoto; Young, Mattew R; Colburn, Nancy

    2004-01-01

    Anthocyanins are the chemical components that give the intense color to many fruits and vegetables, such as blueberries, red cabbages and purple sweet potatoes. Extensive studies have indicated that anthocyanins have strong antioxidant activities. To investigate the mechanism of anthocyanidins as an anticancer food source, six kinds of anthocyanidins representing the aglycons of most anthocyanins, were used to examine their effects on tumor promotion in mouse JB6 cells, a validated model for screening cancer chemopreventive agents and elucidating the molecular mechanisms. Of the six anthocyanins tested, only those with an ortho-dihydroxyphenyl structure on the B-ring suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation and activator protein-1 transactivation, suggesting that the ortho-dihydroxyphenyl may contribute to the inhibitory action. Delphinidin, but not peonidin, blocked the phosphorylation of protein kinases in the extracellular signal-regulated protein kinase (ERK) pathway at early times and the c-Jun N-terminal kinase (JNK) signaling pathway at later times. p38 kinase was not inhibited by delphinidin. Furthermore, two mitogen-activated protein kinase (MAPK) specific inhibitors (SP600125 for JNK and UO126 for ERK) could specifically block the activation of JNK and ERK and cell transformation. Those results demonstrate that anthocyanidins contribute to the inhibition of tumorigenesis by blocking activation of the MAPK pathway. These findings provide the first molecular basis for the anticarcinogenic action of anthocyanidins.

  1. 24 CFR 1003.209 - Prohibition on use of assistance for employment relocation activities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... recipient, is longer than 3 years. (c) Written agreement. Before directly assisting a business with ICDBG... apply to: (1) Relocation assistance. Relocation assistance under § 1003.602(b), (c), or (d); (2... Development Act of 1974; and (3) Arms-length transactions. Assistance to a business that purchases...

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

    ERIC Educational Resources Information Center

    Clemson Univ., SC. Vocational Education Media Center.

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

  3. Efficiency of assisted oocyte activation as a solution for failed intracytoplasmic sperm injection.

    PubMed

    Heindryckx, Björn; De Gheselle, Stefanie; Gerris, Jan; Dhont, Marc; De Sutter, Petra

    2008-11-01

    Failed fertilization after intracytoplasmic sperm injection (ICSI) can occur due to an oocyte activation defect. In these cases assisted oocyte activation (AOA) may help but efficiency is still unknown. Prior to AOA, the mouse oocyte activation test (MOAT) can be carried out by injecting human spermatozoa into mouse oocytes to evaluate their activating capacity. According to the MOAT activation percentage achieved, patients were classified into three groups: 0-20% (16 patients); 20-85% (seven patients); 85-100% (seven patients). For AOA, CaCl(2) was injected together with spermatozoa followed by a double Ca(2+) ionophore treatment. The fertilization rates before application of AOA in 50 cycles were 6%, 22% and 14% in, respectively, groups 1, 2 and 3 without any pregnancy. Fertilization and pregnancy rates after AOA in 61 cycles were significantly increased to 75% and 34% for group 1, 73% and 43% for group 2, and 75% and 17% for group 3 (P < 0.0001 and P < 0.004, respectively). Application of AOA results in normal fertilization and pregnancy rates in patients whose spermatozoa show deficient activation. When MOAT reveals no activation deficiency in spermatozoa, AOA still allows for high fertilization and acceptable pregnancy rates. The obstetric and neonatal outcomes after AOA were normal as no malformations were observed.

  4. Development of a Smartphone Application to Measure Physical Activity Using Sensor-Assisted Self-Report

    PubMed Central

    Dunton, Genevieve Fridlund; Dzubur, Eldin; Kawabata, Keito; Yanez, Brenda; Bo, Bin; Intille, Stephen

    2013-01-01

    Introduction: Despite the known advantages of objective physical activity monitors (e.g., accelerometers), these devices have high rates of non-wear, which leads to missing data. Objective activity monitors are also unable to capture valuable contextual information about behavior. Adolescents recruited into physical activity surveillance and intervention studies will increasingly have smartphones, which are miniature computers with built-in motion sensors. Methods: This paper describes the design and development of a smartphone application (“app”) called Mobile Teen that combines objective and self-report assessment strategies through (1) sensor-informed context-sensitive ecological momentary assessment (CS-EMA) and (2) sensor-assisted end-of-day recall. Results: The Mobile Teen app uses the mobile phone’s built-in motion sensor to automatically detect likely bouts of phone non-wear, sedentary behavior, and physical activity. The app then uses transitions between these inferred states to trigger CS-EMA self-report surveys measuring the type, purpose, and context of activity in real-time. The end of the day recall component of the Mobile Teen app allows users to interactively review and label their own physical activity data each evening using visual cues from automatically detected major activity transitions from the phone’s built-in motion sensors. Major activity transitions are identified by the app, which cues the user to label that “chunk,” or period, of time using activity categories. Conclusion: Sensor-driven CS-EMA and end-of-day recall smartphone apps can be used to augment physical activity data collected by objective activity monitors, filling in gaps during non-wear bouts and providing additional real-time data on environmental, social, and emotional correlates of behavior. Smartphone apps such as these have potential for affordable deployment in large-scale epidemiological and intervention studies. PMID:24616888

  5. In vitro evaluation of an external compression device for fontan mechanical assistance.

    PubMed

    Valdovinos, John; Shkolyar, Eugene; Carman, Gregory P; Levi, Daniel S

    2014-03-01

    While Fontan palliation in the form of the total cavopulmonary connection has improved the management of congenital single ventricle physiology, long-term outcomes for patients with this disease are suboptimal due to the lack of two functional ventricles. Researchers have shown that ventricular assist devices (VADs) can normalize Fontan hemodynamics. To minimize blood contacting surfaces of the VAD, we evaluated the use of an external compression device (C-Pulse Heart Assist System, Sunshine Heart Inc.) as a Fontan assist device. A mock circulation was developed to mimic the hemodynamics of a hypertensive Fontan circulation in a pediatric patient. The Sunshine C-Pulse compression cuff was coupled with polymeric valves and a compressible tube to provide nonblood-contacting pulsatile flow through the Fontan circulation. The effect of the number, one or two, and placement of valves, before or after the compression cuff, on inferior vena cava pressure (IVCP) was studied. In addition, the effect of device inflation volume and compression rate on maintaining low IVCP was investigated. With one valve located before the cuff, the device was unable to maintain an IVCP below 15.5 mm Hg. With two valves, the C-Pulse was able to maintain IVCP as low as 8.5 mm Hg. The C-Pulse provided pulsatile flow and pressure through the pulmonary branch of the mock circulation with a pulse pressure of 16 mm Hg and 180 mL/min additional flow above unassisted flow. C-Pulse compression reduced IVCP below 12 mm Hg with 13 cc inflation volume and compression rates above 105 bpm. This application of an external compression device combined with two valves has potential for use as an artificial right ventricle by maintaining low IVCP and providing pulsatile flow through the lungs.

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

    PubMed Central

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

    2016-01-01

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

  7. Dynamic optimization of walker-assisted FES-activated paraplegic walking: simulation and experimental studies.

    PubMed

    Nekoukar, Vahab; Erfanian, Abbas

    2013-11-01

    In this paper, we propose a musculoskeletal model of walker-assisted FES-activated paraplegic walking for the generation of muscle stimulation patterns and characterization of the causal relationships between muscle excitations, multi-joint movement, and handle reaction force (HRF). The model consists of the lower extremities, trunk, hands, and a walker. The simulation of walking is performed using particle swarm optimization to minimize the tracking errors from the desired trajectories for the lower extremity joints, to reduce the stimulations of the muscle groups acting around the hip, knee, and ankle joints, and to minimize the HRF. The results of the simulation studies using data recorded from healthy subjects performing walker-assisted walking indicate that the model-generated muscle stimulation patterns are in agreement with the EMG patterns that have been reported in the literature. The experimental results on two paraplegic subjects demonstrate that the proposed methodology can improve walking performance, reduce HRF, and increase walking speed when compared to the conventional FES-activated paraplegic walking.

  8. Cellulase-assisted extraction of polysaccharides from Cucurbita moschata and their antibacterial activity.

    PubMed

    Qian, Zhi-Gang

    2014-01-30

    In this study, cellulase-assisted extraction of water soluble polysaccharides from pumpkin (Cucurbita moschata) and their antibacterial activity were investigated. The polysaccharides yield was monitored during the extraction process. The optimum extraction conditions were determined as follows: time, 40 min; temperature, 55°C; pH, 4.5; and cellulase amount, 4,000 U/g. The extracts were centrifuged, filtered, proteins removed by Sevag method, concentrated to approximately 15% (w/v), precipitated with 5 volumes of absolute ethanol, freeze-dried, and pulverized to yield a water soluble powder of pumpkin polysaccharides (PP). The sugar content of the product was 68.3%, and the yield was 17.34% (w/w), respectively. The PP had high antibacterial activity against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli at the concentration of 100 mg/mL.

  9. Cellulase-assisted extraction and antibacterial activity of polysaccharides from the dandelion Taraxacum officinale.

    PubMed

    Wang, Hong-Bin

    2014-03-15

    In the present study, we investigated the cellulase-assisted extraction and antibacterial activity of water-soluble polysaccharides from the dandelion Taraxacum officinale. The extraction conditions, optimized for improving yield, were as follows: time, 46.11 min; temperature, 54.87 °C; pH, 4.51 and cellulase enzyme, 4000 U/g. Under these conditions, the yield of polysaccharides from dandelion (PD) reached 20.67% (w/w). The sugar content of PD was 95.6% (w/w), and it displayed high antibacterial activity at a concentration of 100mg/mL against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. These results indicate that PD may be a viable option for use as a food preservative.

  10. Effect of pressure assist on ventilation and respiratory mechanics in heavy exercise.

    PubMed

    Gallagher, C G; Younes, M

    1989-04-01

    To assess the effect of the normal respiratory resistive load on ventilation (VE) and respiratory motor output during exercise, we studied the effect of flow-proportional pressure assist (PA) (2.2 cmH2O.l-1.s) on various ventilatory parameters during progressive exercise to maximum in six healthy young men. We also measured dynamic lung compliance (Cdyn) and lung resistance (RL) and calculated the time course of respiratory muscle pressure (Pmus) during the breath in the assisted and unassisted states at a sustained exercise level corresponding to 70-80% of the subject's maximum O2 consumption. Unlike helium breathing, resistive PA had no effect on VE or any of its subdivisions partly as the result of an offsetting increase in RL (0.78 cmH2O.1-1.s) and partly to a reduction in Pmus. These results indicate that the normal resistive load does not constrain ventilation during heavy exercise. Furthermore, the increase in exercise ventilation observed with helium breathing, which is associated with much smaller degrees of resistive unloading (ca. -0.6 cmH2O.l-1.s), is likely the result of factors other than respiratory muscle unloading. The pattern of Pmus during exercise with and without unloading indicates that the use of P0.1 as an index of respiratory motor output under these conditions may result in misleading conclusions.

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

    PubMed

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

    2004-01-01

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

  12. Application of flexure structures to active and adaptive opto-mechanical mechanisms

    NASA Astrophysics Data System (ADS)

    Zago, Lorenzo; Genequand, Pierre M.; Kjelberg, Ivar; Morschel, Joseph

    1997-03-01

    Active and adaptive structures, also commonly called 'smart' structures, combine in one integrated system various functions such as load carrying and structural function, mechanical (cinematic) functions, sensing, control and actuating. Originally developed for high accuracy opto-mechanical applications, CSEM's technology of flexure structures and flexible mechanisms is particularly suited to solve many structural and mechanical issues found in such active/adaptive mechanisms. The paper illustrates some recent flexure structures developments at CSEM and outlines the comprehensive know-how involved in this technology. This comprises in particular the elaboration of optimal design guidelines, related to the geometry, kinematics and dynamics issues (for instance, the minimization of spurious high frequency effects), the evaluation and predictability of all performance quantities relevant to the utilization of flexure structures in space (reliability, fatigue, static and dynamic modeling, etc.). material issues and manufacturing procedures.

  13. Active vibration control using mechanical and electrical analogies

    NASA Astrophysics Data System (ADS)

    Torres-Perez, A.; Hassan, A.; Kaczmarczyk, S.; Picton, P.

    2016-05-01

    Mechanical-electrical analogous circuit models are widely used in electromechanical system design as they represent the function of a coupled electrical and mechanical system using an equivalent electrical system. This research uses electrical circuits to establish a discussion of simple active vibration control principles using two scenarios: an active vibration isolation system and an active dynamic vibration absorber (DVA) using a voice coil motor (VCM) actuator. Active control laws such as gain scheduling are intuitively explained using circuit analysis techniques. Active vibration control approaches are typically constraint by electrical power requirements. The electrical analogous is a fast approach for specifying power requirements on the experimental test platform which is based on a vibration shaker that provides the based excitation required for the single Degree- of-Freedom (1DoF) vibration model under study.

  14. Cellular and Molecular Mechanisms Underpinning Macrophage Activation during Remyelination

    PubMed Central

    Lloyd, Amy F.; Miron, Veronique E.

    2016-01-01

    Remyelination is an example of central nervous system (CNS) regeneration, whereby myelin is restored around demyelinated axons, re-establishing saltatory conduction and trophic/metabolic support. In progressive multiple sclerosis, remyelination is limited or fails altogether which is considered to contribute to axonal damage/loss and consequent disability. Macrophages have critical roles in both CNS damage and regeneration, such as remyelination. This diverse range in functions reflects the ability of macrophages to acquire tissue microenvironment-specific activation states. This activation is dynamically regulated during efficient regeneration, with a switch from pro-inflammatory to inflammation-resolution/pro-regenerative phenotypes. Although, some molecules and pathways have been implicated in the dynamic activation of macrophages, such as NFκB, the cellular and molecular mechanisms underpinning plasticity of macrophage activation are unclear. Identifying mechanisms regulating macrophage activation to pro-regenerative phenotypes may lead to novel therapeutic strategies to promote remyelination in multiple sclerosis. PMID:27446913

  15. Dynamic expression profiles of MMPs/TIMPs and collagen deposition in mechanically unloaded rat heart: implications for left ventricular assist device support-induced cardiac alterations.

    PubMed

    Wang, Lu; Xu, Yu-Xian; Du, Xiao-Jie; Sun, Quan-Ge; Tian, Ying-Jun

    2013-09-01

    Left ventricular assist devices (LVADs) ameliorate heart failure by reducing preload and afterload. However, extracellular matrix (ECM) deposition after application of LVADs is not clearly defined. The purpose of the present study was to investigate ECM remodeling after mechanical unloading in a rat heart transplant model. Sixty male Lewis rats were subjected to abdominal heterotopic heart transplantation, and the transplanted hearts were pressure- and volume-unloaded. The age- and weight- matched male Lewis rats who had undergone open thoracic surgeries were used as the control. Left ventricle ECM accumulation and the expression/activity of matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases (TIMPs) were measured on the third, seventh, and fourteenth days after transplantation/sham surgery. Compared with the control group, myocardial ECM deposition significantly increased on the seventh and fourteenth days after heart transplantation (P < 0.05) and peaked on the 14th day. The gelatinase activity as well as mRNA expression of MMP-2 and MMP-9 significantly increased after transplantation (P < 0.05). Both mRNA and protein levels of TIMP-1 and TIMP-2 significantly increased compared with those of the control group. Mechanical unloading may lead to adverse remodeling of the ECM of the left ventricle. The underlying mechanism may due to the imbalance of the MMP/TIMP system, especially the remarkable upregulation of TIMPs in the pressure and volume unloaded heart.

  16. Chaperone-like activities of {alpha}-synuclein: {alpha}-Synuclein assists enzyme activities of esterases

    SciTech Connect

    Ahn, Misun; Kim, SeungBum; Kang, Mira; Ryu, Yeonwoo . E-mail: ywryu@ajou.ac.kr; Doohun Kim, T. . E-mail: doohunkim@ajou.ac.kr

    2006-08-11

    {alpha}-Synuclein, a major constituent of Lewy bodies (LBs), has been implicated to play a critical role in the pathogenesis of Parkinson's disease (PD), although the physiological function of {alpha}-synuclein has not yet been known. Here we have shown that {alpha}-synuclein, which has no well-defined secondary or tertiary structure, can protect the enzyme activity of microbial esterases against stress conditions such as heat, pH, and organic solvents. In particular, the flexibility of {alpha}-synuclein and its C-terminal region seems to be important for complex formation, but the structural integrity of the C-terminal region may not be required for stabilization of enzyme activity. In addition, atomic force microscopy (AFM) and in vivo enzyme assays showed highly specific interactions of esterases with {alpha}-synuclein. Our results indicate that {alpha}-synuclein not only protects the enzyme activity of microbial esterases in vitro, but also can stabilize the active conformation of microbial esterases in vivo.

  17. Biological mechanisms of physical activity in preventing cognitive decline.

    PubMed

    Lista, I; Sorrentino, G

    2010-05-01

    In order to guarantee better conditions for competition, the nervous system has developed not only mechanisms controlling muscle effectors, but also retrograde systems that, starting from peripheral structures, may influence brain functions. Under such perspective, physical activity could play an important role in influencing cognitive brain functions including learning and memory. The results of epidemiological studies (cross-sectional, prospective and retrospective) support a positive relationship between cognition and physical activities. Recent meta-analysis confirmed a significant effect of exercise on cognitive functions. However, the biological mechanisms that underlie such beneficial effects are still to be completely elucidated. They include supramolecular mechanisms (e.g. neurogenesis, synaptogenesis, and angiogenesis) which, in turn, are controlled by molecular mechanisms, such as BDNF, IGF-1, hormone and second messengers.

  18. Exploded view of higher order G-quadruplex structures through click-chemistry assisted single-molecule mechanical unfolding.

    PubMed

    Selvam, Sangeetha; Yu, Zhongbo; Mao, Hanbin

    2016-01-01

    Due to the long-range nature of high-order interactions between distal components in a biomolecule, transition dynamics of tertiary structures is often too complex to profile using conventional methods. Inspired by the exploded view in mechanical drawing, here, we used laser tweezers to mechanically dissect high-order DNA structures into two constituting G-quadruplexes in the promoter of the human telomerase reverse transcriptase (hTERT) gene. Assisted with click-chemistry coupling, we sandwiched one G-quadruplex with two dsDNA handles while leaving the other unit free. Mechanical unfolding through these handles revealed transition dynamics of the targeted quadruplex in a native environment, which is named as native mechanical segmentation (NMS). Comparison between unfolding of an NMS construct and that of truncated G-quadruplex constructs revealed a quadruplex-quadruplex interaction with 2 kcal/mol stabilization energy. After mechanically targeting the two G-quadruplexes together, the same interaction was observed during the first unfolding step. The unfolding then proceeded through disrupting the weaker G-quadruplex at the 5'-end, followed by the stronger G-quadruplex at the 3'-end via various intermediates. Such a pecking order in unfolding well reflects the hierarchical nature of nucleic acid structures. With surgery-like precisions, we anticipate this NMS approach offers unprecedented perspective to decipher dynamic transitions in complex biomacromolecules.

  19. Exploded view of higher order G-quadruplex structures through click-chemistry assisted single-molecule mechanical unfolding

    PubMed Central

    Selvam, Sangeetha; Yu, Zhongbo; Mao, Hanbin

    2016-01-01

    Due to the long-range nature of high-order interactions between distal components in a biomolecule, transition dynamics of tertiary structures is often too complex to profile using conventional methods. Inspired by the exploded view in mechanical drawing, here, we used laser tweezers to mechanically dissect high-order DNA structures into two constituting G-quadruplexes in the promoter of the human telomerase reverse transcriptase (hTERT) gene. Assisted with click-chemistry coupling, we sandwiched one G-quadruplex with two dsDNA handles while leaving the other unit free. Mechanical unfolding through these handles revealed transition dynamics of the targeted quadruplex in a native environment, which is named as native mechanical segmentation (NMS). Comparison between unfolding of an NMS construct and that of truncated G-quadruplex constructs revealed a quadruplex–quadruplex interaction with 2 kcal/mol stabilization energy. After mechanically targeting the two G-quadruplexes together, the same interaction was observed during the first unfolding step. The unfolding then proceeded through disrupting the weaker G-quadruplex at the 5′-end, followed by the stronger G-quadruplex at the 3′-end via various intermediates. Such a pecking order in unfolding well reflects the hierarchical nature of nucleic acid structures. With surgery-like precisions, we anticipate this NMS approach offers unprecedented perspective to decipher dynamic transitions in complex biomacromolecules. PMID:26626151

  20. Reliability of estimating active drag in swimming using the assisted towing method with fluctuating speed.

    PubMed

    Hazrati, Pendar; Sinclair, Peter James; Ferdinands, René Edouard; Mason, Bruce Robert

    2016-09-01

    The reliability of active drag values was examined using a method that compared free swim speed with measurements taken by towing swimmers slightly faster than their maximum swim speed, while allowing their intra-stroke speed fluctuations. Twelve national age and open level swimmers were tested on two alternate days (Day 1 and Day 2). All participants completed four maximum swim speed, three passive drag and five active drag trials on each of the days. The reliability was determined using within-participant intra-class correlation coefficients (ICC) within each day and between the days. The ICCs for Day 1 and Day 2 were 0.82 and 0.85, respectively, while the comparison of the mean active drag values between days was 0.93. The data showed that the assisted towing method (ATM) with fluctuating speed was only moderately reliable within a single test. However, this method was more reliable when using the average value of active drag from both days (ICC = 0.93). This study identified that the ATM method with fluctuating speed had moderate reliability within-participant trials on values in a single day but high reliability for the average active drag values across different days.

  1. Mechanisms of Activation of Voltage-Gated Potassium Channels

    PubMed Central

    Grizel, A. V.; Glukhov, G. S.; Sokolova, O. S.

    2014-01-01

    Voltage-gated potassium ion channels (Kv) play an important role in a variety of cellular processes, including the functioning of excitable cells, regulation of apoptosis, cell growth and differentiation, the release of neurotransmitters and hormones, maintenance of cardiac activity, etc. Failure in the functioning of Kv channels leads to severe genetic disorders and the development of tumors, including malignant ones. Understanding the mechanisms underlying Kv channels functioning is a key factor in determining the cause of the diseases associated with mutations in the channels, and in the search for new drugs. The mechanism of activation of the channels is a topic of ongoing debate, and a consensus on the issue has not yet been reached. This review discusses the key stages in studying the mechanisms of functioning of Kv channels and describes the basic models of their activation known to date. PMID:25558391

  2. Jahn-Teller assisted polaronic hole hopping as a charge transport mechanism in CuO nanograins

    NASA Astrophysics Data System (ADS)

    Younas, M.; Nadeem, M.; Idrees, M.; Akhtar, M. J.

    2012-04-01

    Impedance spectroscopy has been employed to investigate the dielectric and electric transport phenomena in sol-gel synthesized CuO nanograins. Semiconducting features of the grains and grain boundaries have been endorsed to the thermal activation of the localized charge carriers. On cooling below 303 K, a transition from Jahn-Teller polaron hopping mechanism to the Mott's variable range hopping mechanism has been observed owing to random potential fluctuations among localized sites. Activation energies for conduction and relaxation processes at grain boundaries provide strong signatures for the involvement of Jahn-Teller adiabatic small polarons as a charge transport mechanism in CuO nanograins.

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

    PubMed

    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. PMID:26819083

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

    NASA Astrophysics Data System (ADS)

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

    PubMed

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-28

    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.

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

    PubMed Central

    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. PMID:26819083

  7. Modulation of bone remodeling via mechanically activated ion channels

    NASA Technical Reports Server (NTRS)

    Duncan, Randall L. (Principal Investigator)

    1996-01-01

    A critical factor in the maintenance of bone mass is the physical forces imposed upon the skeleton. Removal of these forces, such as in a weightless environment, results in a rapid loss of bone, whereas application of exogenous mechanical strain has been shown to increase bone formation. Numerous flight and ground-based experiments indicate that the osteoblast is the key bone cell influenced by mechanical stimulation. Aside from early transient fluctuations in response to unloading, osteoclast number and activity seem unaffected by removal of strain. However, bone formation is drastically reduced in weightlessness and osteoblasts respond to mechanical strain with an increase in the activity of a number of second messenger pathways resulting in increased anabolic activity. Unfortunately, the mechanism by which the osteoblast converts physical stimuli into a biochemical message, a process we have termed biochemical coupling, remains elusive. Prior to the application of this grant, we had characterized a mechanosensitive, cation nonselective channel (SA-cat) in osteoblast-like osteosarcoma cells that we proposed is the initial signalling mechanism for mechanotransduction. During the execution of this grant, we have made considerable progress to further characterize this channel as well as to determine its role in the osteoblastic response to mechanical strain. To achieve these goals, we combined electrophysiologic techniques with cellular and molecular biology methods to examine the role of these channels in the normal function of the osteoblast in vitro.

  8. Small molecules reveal an alternative mechanism of Bax activation

    PubMed Central

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

    2016-01-01

    The pro-apoptotic protein Bax commits a cell to death by permeabilizing the mitochondrial outer membrane (MOM). To obtain small-molecule probes for elucidating the molecular mechanism(s) of Bax activation, we screened for compounds that induced Bax-mediated liposome permeabilization. We identified five structurally different small molecules that promoted both Bax targeting to and oligomerization at membranes. All five compounds initiated Bax oligomerization in the absence of membranes by a mechanism unlike Bax activation by Bcl-2 homology 3 domain (BH3) proteins. Some of the compounds induced Bax/Bak-dependent apoptosis in cells. Activation of Bax by the most active compound was poorly inhibited by the anti-apoptotic protein Bcl-XL and requires a cysteine residue at position 126 of Bax that is not required for activation by BH3 proteins. Our results reveal a novel pathway for Bax activation independent of pro-apoptotic BH3 proteins that may have important implications for the regulation of Bax activity in cells. PMID:26916338

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

    PubMed

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

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements. PMID:27104932

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

    PubMed

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

    2016-08-01

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

  11. Functional capacity and assistance from the caregiver during daily activities in Brazilian children with cerebral palsy

    PubMed Central

    2013-01-01

    Background Cerebral Palsy (CP) presents changes in posture and movement as a core characteristic, which requires multiprofessional clinical treatments during children’s habilitation or rehabilitation. Besides clinical treatment, it is fundamental that professionals use evaluation systems to quantify the difficulties presented to the individual and their families in their daily lives. We aimed to investigate the functional capacity of individuals with CP and the amount of assistance required by the caregiver in day-to-day activities. Methods Twenty patients with CP, six-year-old on average, were evaluated. The Pediatric Evaluation Inventory of Incapacities was used (PEDI - Pediatric Evaluation Disability Inventory), a system adapted for Brazil that evaluates child's dysfunction in three 3 dimensions: self-care, mobility and social function. To compare the three areas, repeated measures analysis of variance (ANOVA) were used. Results We found the following results regarding the functional capacity of children: self-care, 27.4%, ±17.5; mobility, 25.8%, ±33.3 and social function, 36.3%, ±27.7. The results of the demand of aid from the caregiver according to each dimension were: self-care, 9.7%, ±19.9; mobility, 14.1%, ± 20.9 and social function, 19.8%, ±26.1. Conclusion We indicated that there was no difference between the performance of the subjects in areas of self-care, mobility and social function considering the functional skills and assistance required by the caregiver. PMID:23302576

  12. Ultrasonic-assisted extraction, structure and antitumor activity of polysaccharide from Polygonum multiflorum.

    PubMed

    Zhu, Weili; Xue, Xiaoping; Zhang, Zhanjun

    2016-10-01

    Polygonum multiflorum is a popular Chinese herbal medicine with various pharmacological functions. In this study, the ultrasonic-assisted extraction condition, structural characterization and antitumor activity of a polysaccharide from roots of P. multiflorum were investigated. The ultrasonic-assisted extraction condition was optimized by single-factor experiments and response surface methodology. Results showed that the maximum extraction yield (5.49%) was obtained at ultrasonic power 158W, extraction temperature 62°C, extraction time 80min and ratio of water to material 20mL/g. The obtained crude polysaccharides were further purified to afford a neutral and an acidic fraction. The structure of the main neutral polysaccharide (named PPS with molecular weight of 3.26×10(5)Da) was characterized as a linear (1→6)-α-d-glucan by gas chromatography, Fourier transform-infrared spectroscopy, methylation analysis, 1D and 2D nuclear magnetic resonance. At the concentration of 400μg/mL, the inhibitory ratios of PPS on HepG-2 and BGC-823 cells were 53.35% and 38.58%, respectively. Results suggested this polysaccharide could be a potential natural antitumor agent. PMID:27212220

  13. Natural healers: a review of animal assisted therapy and activities as complementary treatment for chronic conditions.

    PubMed

    Reed, Reiley; Ferrer, Lilian; Villegas, Natalia

    2012-01-01

    The primary objective of this review is to synthesize the existing literature on the use of animal-assisted therapy and activity (AAT/A) as complementary treatment among people living with chronic disease and to discuss the possible application of this practice among children living with HIV. Relevant databases were searched between March 10 and April 11, 2011, using the words: animal assisted therapy or treatment and chronic conditions or diseases. Thirty-one articles were found and 18 followed the inclusion and exclusion criteria. Research suggests that AAT/A is effective for different patient profiles, particularly children. Interaction with dogs has been found to increase positive behaviors, such as sensitivity and focus, in children with social disabilities. Decreased levels of pain have also been reported among child patients as a result of AAT/A. More research should be done in the area of children living with chronic diseases that require strict adherence to treatment, such as HIV, and on AAT/A's prospective use as an educational tool to teach children about the importance of self-care for their medical conditions.

  14. 77 FR 70995 - Agency Information Collection Activities; Comment Request; Student Assistance General Provisions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-28

    ...--Financial Assistance for Students With Intellectual Disabilities AGENCY: Department of Education (ED...-- Financial Assistance for Students with Intellectual Disabilities. OMB Control Number: 1845-0099. Type of... approved collection for the regulations allowing students with intellectual disabilities who enrolled in...

  15. Proanthocyanidins Extracted from Rhododendron pulchrum Leaves as Source of Tyrosinase Inhibitors: Structure, Activity, and Mechanism

    PubMed Central

    Chai, Wei-Ming; Wang, Rui; Wei, Man-Kun; Zou, Zheng-Rong; Deng, Rong-Gen; Liu, Wei-Sheng; Peng, Yi-Yuan

    2015-01-01

    The objective of this study was to assess the structure, anti-tyrosinase activity, and mechanism of proanthocyanidins extracted from Rhododendron pulchrum leaves. Results obtained from mass spectra of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) revealed that proanthocyanidins were complex mixtures of procyanidins, prodelphinidins, propelargonidins, and their derivatives, among which procyanidins were the main components. The anti-tyrosinase analysis results indicated that the mixtures were reversible and mixed competitive inhibitors of tyrosinase. Interactions between proanthocyanidins with substrate (L-tyrosine and 3,4-dihydroxyphenylalanine) and with copper ions were the important molecular mechanisms for explaining their efficient inhibition. This research would provide scientific evidence for the use of R. pulchrum leaf proanthocyanidins as new novel tyrosinase inhibitors. PMID:26713623

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

    PubMed Central

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

    2012-01-01

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

  17. DNA sequence-dependent mechanics and protein-assisted bending in repressor-mediated loop formation

    PubMed Central

    Boedicker, James Q.; Garcia, Hernan G.; Johnson, Stephanie; Phillips, Rob

    2014-01-01

    As the chief informational molecule of life, DNA is subject to extensive physical manipulations. The energy required to deform double-helical DNA depends on sequence, and this mechanical code of DNA influences gene regulation, such as through nucleosome positioning. Here we examine the sequence-dependent flexibility of DNA in bacterial transcription factor-mediated looping, a context for which the role of sequence remains poorly understood. Using a suite of synthetic constructs repressed by the Lac repressor and two well-known sequences that show large flexibility differences in vitro, we make precise statistical mechanical predictions as to how DNA sequence influences loop formation and test these predictions using in vivo transcription and in vitro single-molecule assays. Surprisingly, sequence-dependent flexibility does not affect in vivo gene regulation. By theoretically and experimentally quantifying the relative contributions of sequence and the DNA-bending protein HU to DNA mechanical properties, we reveal that bending by HU dominates DNA mechanics and masks intrinsic sequence-dependent flexibility. Such a quantitative understanding of how mechanical regulatory information is encoded in the genome will be a key step towards a predictive understanding of gene regulation at single-base pair resolution. PMID:24231252

  18. Ultrasound-assisted extraction, HPLC analysis, and antioxidant activity of polyphenols from unripe apple.

    PubMed

    Yue, Tianli; Shao, Dongyan; Yuan, Yahong; Wang, Zhouli; Qiang, Chunyan

    2012-08-01

    The polyphenols were extracted from the unripe apple assisted by a highly efficient and simple method of the ultrasound. Response surface methodology was used to investigate the effects of processing parameters, including ultrasound power, extraction time, temperature, and ethanol concentration on total polyphenols yield and polyphenols composition was analyzed by HPLC. Antioxidant activity of the polyphenols was evaluated as 2, 2-diphenyl-1-picrylhydracyl scavenging activity and inhibition activity of lipid peroxidation. The results showed that 10-100 times higher total polyphenols yield was obtained from the unripe apple than those from the reported apple pomace. The optimum extraction conditions were ultrasonic power of 519.39 W, extraction time of 30 min, extraction temperature 50°C, ethanol concentration of 50% gave the total polyphenols yield of 13.26 ± 0.56 mg GAE/g. HPLC analysis indicated that (-)-epicatechin, procyanidin B2, chlorogenic acid, and procyanidin B1 were the predominant polyphenols in unripe apple, which contributed to the higher antioxidant activity to 2, 2-diphenyl-1-picrylhydracyl of unripe apple polyphenols than other apple polyphenols. The extracted polyphenols had higher ability to inhibit lipid peroxidation than butylated hydroxy toluene, which demonstrated that the unripe apple polyphenols have the potential to be used as a substitute of some synthetic antioxidants.

  19. Active in-database processing to support ambient assisted living systems.

    PubMed

    de Morais, Wagner O; Lundström, Jens; Wickström, Nicholas

    2014-08-12

    As an alternative to the existing software architectures that underpin the development of smart homes and ambient assisted living (AAL) systems, this work presents a database-centric architecture that takes advantage of active databases and in-database processing. Current platforms supporting AAL systems use database management systems (DBMSs) exclusively for data storage. Active databases employ database triggers to detect and react to events taking place inside or outside of the database. DBMSs can be extended with stored procedures and functions that enable in-database processing. This means that the data processing is integrated and performed within the DBMS. The feasibility and flexibility of the proposed approach were demonstrated with the implementation of three distinct AAL services. The active database was used to detect bed-exits and to discover common room transitions and deviations during the night. In-database machine learning methods were used to model early night behaviors. Consequently, active in-database processing avoids transferring sensitive data outside the database, and this improves performance, security and privacy. Furthermore, centralizing the computation into the DBMS facilitates code reuse, adaptation and maintenance. These are important system properties that take into account the evolving heterogeneity of users, their needs and the devices that are characteristic of smart homes and AAL systems. Therefore, DBMSs can provide capabilities to address requirements for scalability, security, privacy, dependability and personalization in applications of smart environments in healthcare.

  20. Carbon nanotube-assisted optical activation of TGF-β signalling by near-infrared light

    NASA Astrophysics Data System (ADS)

    Lin, Liang; Liu, Ling; Zhao, Bing; Xie, Ran; Lin, Wei; Li, He; Li, Yaya; Shi, Minlong; Chen, Ye-Guang; Springer, Timothy A.; Chen, Xing

    2015-05-01

    Receptor-mediated signal transduction modulates complex cellular behaviours such as cell growth, migration and differentiation. Although photoactivatable proteins have emerged as a powerful tool for controlling molecular interactions and signalling cascades at precise times and spaces using light, many of these light-sensitive proteins are activated by ultraviolent or visible light, which has limited tissue penetration. Here, we report a single-walled carbon nanotube (SWCNT)-assisted approach that enables near-infrared light-triggered activation of transforming growth factor β (TGF-β) signal transduction, an important signalling pathway in embryonic development and cancer progression. The protein complex of TGF-β and its latency-associated peptide is conjugated onto SWCNTs, where TGF-β is inactive. Upon near-infrared irradiation, TGF-β is released through the photothermal effect of SWCNTs and becomes active. The released TGF-β activates downstream signal transduction in live cells and modulates cellular behaviours. Furthermore, preliminary studies show that the method can be used to mediate TGF-β signalling in living mice.

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

    PubMed

    Han, Jingfen; Miranda-Saavedra, Diego; Luebbering, Nathan; Singh, Aman; Sibbet, Gary; Ferguson, Michael A J; Cleghon, Vaughn

    2012-01-01

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

  2. Mechanisms of NOD-like receptor-associated inflammasome activation.

    PubMed

    Wen, Haitao; Miao, Edward A; Ting, Jenny P-Y

    2013-09-19

    A major function of a subfamily of NLR (nucleotide-binding domain, leucine-rich repeat containing, or NOD-like receptor) proteins is in inflammasome activation, which has been implicated in a multitude of disease models and human diseases. This work will highlight key progress in understanding the mechanisms that activate the best-studied NLRs (NLRP3, NLRC4, NAIP, and NLRP1) and in uncovering inflammasome NLRs. PMID:24054327

  3. Peer assisted learning in the clinical setting: an activity systems analysis.

    PubMed

    Bennett, Deirdre; O'Flynn, Siun; Kelly, Martina

    2015-08-01

    Peer assisted learning (PAL) is a common feature of medical education. Understanding of PAL has been based on processes and outcomes in controlled settings, such as clinical skills labs. PAL in the clinical setting, a complex learning environment, requires fresh evaluation. Socio-cultural theory is proposed as a means to understand educational interventions in ways that are practical and meaningful. We describe the evaluation of a PAL intervention, introduced to support students' transition into full time clinical attachments, using activity theory and activity systems analysis (ASA). Our research question was How does PAL transfer to the clinical environment? Junior students on their first clinical attachments undertook a weekly same-level, reciprocal PAL activity. Qualitative data was collected after each session, and focus groups (n = 3) were held on completion. Data was analysed using ASA. ASA revealed two competing activity systems on clinical attachment; Learning from Experts, which students saw as the primary function of the attachment and Learning with Peers, the PAL intervention. The latter took time from the first and was in tension with it. Tensions arose from student beliefs about how learning takes place in clinical settings, and the importance of social relationships, leading to variable engagement with PAL. Differing perspectives within the group were opportunities for expansive learning. PAL in the clinical environment presents challenges specific to that context. Using ASA helped to describe student activity on clinical attachment and to highlight tensions and contradictions relating PAL in that setting. Planning learning opportunities on clinical placements, must take account of how students learn in workplaces, and the complexity of the multiple competing activity systems related to learning and social activities.

  4. UNDERSTANDING THE MECHANISMS CONTROLLING ENVIRONMENTALLY-ASSISTED INTERGRANULAR CRACKING OF NICKEL-BASE ALLOYS

    SciTech Connect

    Gary S. Was

    2004-02-13

    Creep and IG cracking of nickel-base alloys depend principally on two factors--the deformation behavior and the effect of the environment. We have shown that both contribute to the observed degradation in primary water. The understanding of cracking does not lie wholly within the environmental effects arena, nor can it be explained only by intrinsic mechanical behavior. Rather, both processes contribute to the observed behavior in primary water. In this project, we had three objectives: (1) to verify that grain boundaries control deformation in Ni-16Cr-9Fe at 360 C, (2) to identify the environmental effect on IGSCC, and (3) to combine CSLBs and GBCs to maximize IGSCC resistance in Ni-Cr-Fe in 360 C primary water. Experiments performed in hydrogen gas at 360 C confirm an increase in the primary creep rate in Ni-16Cr-9Fe at 360 C due to hydrogen. The creep strain transients caused by hydrogen are proposed to be due to the collapse of dislocation pile-ups, as confirmed by observations in HVEM. The observations only partially support the hydrogen-enhanced plasticity model, but also suggest a potential role of vacancies in the accelerate creep behavior in primary water. In high temperature oxidation experiments designed to examine the potential for selective internal oxidation in the IGSCC process, cracking is greatest in the more oxidizing environments compared to the low oxygen potential environments where nickel metal is stable. In Ni-Cr-Fe alloys, chromium oxides form preferentially along the grain boundaries, even at low oxygen potential, supporting a potential role in grain boundary embrittlement due to preferential oxidation. Experiments designed to determine the role of grain boundary deformation on intergranular cracking have established, for the first time, a cause-and-effect relationship between grain boundary deformation and IGSCC. That is, grain boundary deformation in Ni-16Cr-9Fe in 360 C primary water leads to IGSCC of the deformed boundaries. As well

  5. A simulation environment for assisting system design of coherent laser doppler wind sensor for active wind turbine pitch control

    NASA Astrophysics Data System (ADS)

    Shinohara, Leilei; Pham Tran, Tuan Anh; Beuth, Thorsten; Umesh Babu, Harsha; Heussner, Nico; Bogatscher, Siegwart; Danilova, Svetlana; Stork, Wilhelm

    2013-05-01

    In order to assist a system design of laser coherent Doppler wind sensor for active pitch control of wind turbine systems (WTS), we developed a numerical simulation environment for modeling and simulation of the sensor system. In this paper we present this simulation concept. In previous works, we have shown the general idea and the possibility of using a low cost coherent laser Doppler wind sensing system for an active pitch control of WTS in order to achieve a reduced mechanical stress, increase the WTS lifetime and therefore reduce the electricity price from wind energy. Such a system is based on a 1.55μm Continuous-Wave (CW) laser plus an erbium-doped fiber amplifier (EDFA) with an output power of 1W. Within this system, an optical coherent detection method is chosen for the Doppler frequency measurement in megahertz range. A comparatively low cost short coherent length laser with a fiber delay line is used for achieving a multiple range measurement. In this paper, we show the current results on the improvement of our simulation by applying a Monte Carlo random generation method for positioning the random particles in atmosphere and extend the simulation to the entire beam penetrated space by introducing a cylindrical co-ordinate concept and meshing the entire volume into small elements in order to achieve a faster calculation and gain more realistic simulation result. In addition, by applying different atmospheric parameters, such as particle sizes and distributions, we can simulate different weather and wind situations.

  6. Multivariable Dynamic Ankle Mechanical Impedance With Active Muscles

    PubMed Central

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quantified when muscles were active. Measurements were performed at five different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsiflexion–plantarflexion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients. PMID:25203497

  7. Antioxidant Activity and Phenolic Content of Microwave-Assisted Solanum melongena Extracts

    PubMed Central

    Modica, Maria N.; Pittalà, Valeria; Siracusa, Maria A.; Sorrenti, Valeria; Acquaviva, Rosaria

    2014-01-01

    Eggplant fruit is a very rich source of polyphenol compounds endowed with antioxidant properties. The aim of this study was to extract polyphenols from eggplant entire fruit, pulp, or skin, both fresh and dry, and compare results between conventional extraction and microwave-assisted extraction (MAE). The effects of time exposure (15, 30, 60, and 90 min) and solvent (water 100% or ethanol/water 50%) were also evaluated. The highest amount of polyphenols was found in the extract obtained from dry peeled skin treated with 50% aqueous ethanol, irradiated with microwave; this extract contained also high quantity of flavonoids and showed good antioxidant activity expressed by its capacity to scavenge superoxide anion and to inhibit lipid peroxidation. PMID:24683354

  8. Microwave assisted extraction of sulfated polysaccharides (fucoidan) from Ascophyllum nodosum and its antioxidant activity.

    PubMed

    Yuan, Yuan; Macquarrie, Duncan

    2015-09-20

    Sulfated polysaccharides (fucoidan) from brown seaweed Ascophyllum nodosum were extracted by microwave assisted extraction (MAE) technology. Different conditions of temperature (90-150°C), extraction time (5-30 min) were evaluated and optimal fucoidan yield was 16.08%, obtained from 120°C for 15 min's extraction. Compositional analysis, GPC, HPAEC and IR analysis were employed for characterization of extracted sulfated polysaccharides. Fucose was the main monosaccharide of fucoidan extracted at 90°C while glucuronic acid was the main monosaccharide of fucoidan extracted at 150°C. Both the molecular weight and sulfate content of extracted fucoidan increased with decreasing extraction temperature. All fucoidans exhibited antioxidant activities as measured by DPPH scavenging and reducing power, among which fucoidan extracted at 90°C was highest. This study shows that MAE is an efficient technology to extract sulfated polysaccharides from seaweed and Ascophyllum nodosum could potentially be a resource for natural antioxidants. PMID:26050894

  9. Microwave assisted extraction of sulfated polysaccharides (fucoidan) from Ascophyllum nodosum and its antioxidant activity.

    PubMed

    Yuan, Yuan; Macquarrie, Duncan

    2015-09-20

    Sulfated polysaccharides (fucoidan) from brown seaweed Ascophyllum nodosum were extracted by microwave assisted extraction (MAE) technology. Different conditions of temperature (90-150°C), extraction time (5-30 min) were evaluated and optimal fucoidan yield was 16.08%, obtained from 120°C for 15 min's extraction. Compositional analysis, GPC, HPAEC and IR analysis were employed for characterization of extracted sulfated polysaccharides. Fucose was the main monosaccharide of fucoidan extracted at 90°C while glucuronic acid was the main monosaccharide of fucoidan extracted at 150°C. Both the molecular weight and sulfate content of extracted fucoidan increased with decreasing extraction temperature. All fucoidans exhibited antioxidant activities as measured by DPPH scavenging and reducing power, among which fucoidan extracted at 90°C was highest. This study shows that MAE is an efficient technology to extract sulfated polysaccharides from seaweed and Ascophyllum nodosum could potentially be a resource for natural antioxidants.

  10. Antioxidant activity and phenolic content of microwave-assisted Solanum melongena extracts.

    PubMed

    Salerno, Loredana; Modica, Maria N; Pittalà, Valeria; Romeo, Giuseppe; Siracusa, Maria A; Di Giacomo, Claudia; Sorrenti, Valeria; Acquaviva, Rosaria

    2014-01-01

    Eggplant fruit is a very rich source of polyphenol compounds endowed with antioxidant properties. The aim of this study was to extract polyphenols from eggplant entire fruit, pulp, or skin, both fresh and dry, and compare results between conventional extraction and microwave-assisted extraction (MAE). The effects of time exposure (15, 30, 60, and 90 min) and solvent (water 100% or ethanol/water 50%) were also evaluated. The highest amount of polyphenols was found in the extract obtained from dry peeled skin treated with 50% aqueous ethanol, irradiated with microwave; this extract contained also high quantity of flavonoids and showed good antioxidant activity expressed by its capacity to scavenge superoxide anion and to inhibit lipid peroxidation.

  11. Perceptions of Equine Assisted Activities and Therapies by Parents and Children with Spinal Muscular Atrophy

    PubMed Central

    Lemke, Danielle; Rothwell, Erin; Newcomb, Tara M.; Swoboda, Kathryn J.

    2014-01-01

    Purpose To identify the physical and psychosocial effects of equine assisted activities and therapies (EAAT) on children with Spinal Muscular Atrophy (SMA) from the perspective of the child and their parents. Methods The families of all eligible children with SMA, who reported participation in EAAT, from a western metropolitan academic center were contacted and invited to participate. This study implemented qualitative, semi-structured interviews of children with SMA and their parents. Results Three themes emerged from the qualitative content analysis: physical/psychosocial benefits; relationship development with the horses, instructors, and children; and barriers to continued EAAT engagement. Conclusions The data suggest the overall EAAT experience was a source of enjoyment, self-confidence, and normalcy for the children with SMA. The results of this study provide preliminary support for the use of EAAT among children with SMA. PMID:24675128

  12. Force-Based Puncture Detection and Active Position Holding for Assisted Retinal Vein Cannulation*

    PubMed Central

    Gonenc, Berk; Tran, Nhat; Riviere, Cameron N.; Gehlbach, Peter; Taylor, Russell H.; Iordachita, Iulian

    2016-01-01

    Retinal vein cannulation is a demanding procedure proposed to treat retinal vein occlusion by direct therapeutic agent delivery methods. Challenges in identifying the moment of venous puncture, achieving cannulation and maintaining cannulation during drug delivery currently limit the feasibility of the procedure. In this study, we respond to these problems with an assistive system combining a handheld micromanipulator, Micron, with a force-sensing microneedle. The integrated system senses the instant of vein puncture based on measured forces and the position of the needle tip. The system actively holds the cannulation device securely in the vein following cannulation and during drug delivery. Preliminary testing of the system in a dry phantom, stretched vinyl membranes, demonstrates a significant improvement in the total time the needle could be maintained stably inside of the vein. This was especially evident in smaller veins and is attributed to decreased movement of the positioned cannula following venous cannulation. PMID:27127804

  13. [Protocol of the animal assisted activity program at a university hospital].

    PubMed

    Silveira, Isa Rodrigues; Santos, Nanci Cristiano; Linhares, Daniela Ribeiro

    2011-03-01

    Animal-Assisted Activity (AAA) consists in visitation and recreation through contact with animals, aiming at entertainment and improving the interpersonal relationship between patients and staff. Permission for the animals to visit an Institution requires a protocol with rules and safety routines to avoid accidents and zoonoses. The objective of this study is to describe the important points of the protocol to implement the AAA program. The protocol includes: introduction, objectives, inclusion and exclusion criteria for animals, drivers and patients; recommendations to the handlers and the health team, responsibilities of the Nosocomial Infection Control Committee, zoonoses posters, vaccination schedule for dogs and cats, free-informed consent to take part in the program and records with behavioral analysis of the animals. We believe that disclosing the protocol, based on scientific studies, favors the implementation of new programs in institutions considering the lack of national publications.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  15. Effects of Classroom Animal-Assisted Activities on Social Functioning in Children with Autism Spectrum Disorder

    PubMed Central

    McKenzie, Samantha J.; McCune, Sandra; Slaughter, Virginia

    2014-01-01

    Abstract Objective: The objective of this study was to implement and evaluate a classroom-based Animal-Assisted Activities (AAA) program on social functioning in children with autism spectrum disorder (ASD). Design: This was a multisite, control-to-intervention design study. Settings/location: The study was conducted in 41 classrooms in 15 schools in Brisbane, Australia. Subjects: Sixty-four (64) 5- to 12-year-old children diagnosed with ASD comprised the study group. Intervention: The AAA program consisted of 8 weeks of animal exposure in the school classroom in addition to 16 20-minute animal-interaction sessions. Outcome measures: Teacher- and parent-reported child behavior and social functioning were assessed through standardized instruments at three time points: upon study entry (Time 1), after an 8-week waiting period during the week prior to the AAA program (Time 2), and during the week following the 8-week AAA program (Time 3). Results: Significant improvements were identified in social functioning, including increases in social approach behaviors and social skills, and decreases in social withdrawal behaviors, from before to after the AAA program, but not during the waitlist period. Over half of parents also reported that participants demonstrated an increased interest in attending school during the program. Conclusions: Results demonstrate the feasibility and potential efficacy of a new classroom-based Animal-Assisted Activities model, which may provide a relatively simple and cost-effective means of helping educators and families to improve the social functioning of children with ASD. PMID:24156772

  16. Mechanical Circulatory Support for the Failing Heart: Continuous-Flow Left Ventricular Assist Devices

    PubMed Central

    Englert, Joseph A. R.; Davis, Jennifer A.; Krim, Selim R.

    2016-01-01

    Background: Heart transplantation remains the definitive therapy for patients with advanced heart failure; however, owing to limited donor organ availability and long wait times, continuous-flow left ventricular assist devices (LVADs) have become standard therapy. Methods: This review summarizes the history, progression, function, and basic management of LVADs. Additionally, we provide some clinical pearls and important caveats for managing this unique patient population. Results: Currently, the most common LVADs being implanted in the United States are second- and third-generation devices, the HeartMate II (Thoratec Corp., St. Jude Medical) and the HeartWare HVAD (HeartWare International, Inc.). A newer third-generation pump, the HeartMate III (Thoratec Corp., St. Jude Medical), is designed to create an artificial pulse and is currently under investigation in the United States. Conclusion: LVAD use is promising, will continue to grow, and has become standard therapy for advanced heart failure as a bridge to recovery, as destination therapy, and as a bridge to transplantation. PMID:27660575

  17. Mechanical Circulatory Support for the Failing Heart: Continuous-Flow Left Ventricular Assist Devices

    PubMed Central

    Englert, Joseph A. R.; Davis, Jennifer A.; Krim, Selim R.

    2016-01-01

    Background: Heart transplantation remains the definitive therapy for patients with advanced heart failure; however, owing to limited donor organ availability and long wait times, continuous-flow left ventricular assist devices (LVADs) have become standard therapy. Methods: This review summarizes the history, progression, function, and basic management of LVADs. Additionally, we provide some clinical pearls and important caveats for managing this unique patient population. Results: Currently, the most common LVADs being implanted in the United States are second- and third-generation devices, the HeartMate II (Thoratec Corp., St. Jude Medical) and the HeartWare HVAD (HeartWare International, Inc.). A newer third-generation pump, the HeartMate III (Thoratec Corp., St. Jude Medical), is designed to create an artificial pulse and is currently under investigation in the United States. Conclusion: LVAD use is promising, will continue to grow, and has become standard therapy for advanced heart failure as a bridge to recovery, as destination therapy, and as a bridge to transplantation.

  18. Mechanism of dual specificity kinase activity of DYRK1A.

    PubMed

    Walte, Agnes; Rüben, Katharina; Birner-Gruenberger, Ruth; Preisinger, Christian; Bamberg-Lemper, Simone; Hilz, Nikolaus; Bracher, Franz; Becker, Walter

    2013-09-01

    The function of many protein kinases is controlled by the phosphorylation of a critical tyrosine residue in the activation loop. Dual specificity tyrosine-phosphorylation-regulated kinases (DYRKs) autophosphorylate on this tyrosine residue but phosphorylate substrates on aliphatic amino acids. This study addresses the mechanism of dual specificity kinase activity in DYRK1A and related kinases. Tyrosine autophosphorylation of DYRK1A occurred rapidly during in vitro translation and did not depend on the non-catalytic domains or other proteins. Expression in bacteria as well as in mammalian cells revealed that tyrosine kinase activity of DYRK1A is not restricted to the co-translational autophosphorylation in the activation loop. Moreover, mature DYRK1A was still capable of tyrosine autophosphorylation. Point mutants of DYRK1A and DYRK2 lacking the activation loop tyrosine showed enhanced tyrosine kinase activity. A series of structurally diverse DYRK1A inhibitors was used to pharmacologically distinguish different conformational states of the catalytic domain that are hypothesized to account for the dual specificity kinase activity. All tested compounds inhibited substrate phosphorylation with higher potency than autophosphorylation but none of the tested inhibitors differentially inhibited threonine and tyrosine kinase activity. Finally, the related cyclin-dependent kinase-like kinases (CLKs), which lack the activation loop tyrosine, autophosphorylated on tyrosine both in vitro and in living cells. We propose a model of DYRK autoactivation in which tyrosine autophosphorylation in the activation loop stabilizes a conformation of the catalytic domain with enhanced serine/threonine kinase activity without disabling tyrosine phosphorylation. The mechanism of dual specificity kinase activity probably applies to related serine/threonine kinases that depend on tyrosine autophosphorylation for maturation. PMID:23809146

  19. UNDERSTANDING THE MECHANISMS OF CHANGE IN CHILDREN'S PHYSICAL ACTIVITY PROGRAMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a lack of understanding of why childhood physical activity interventions succeed or fail. A model is proposed that relates program process to mediating variables and outcomes. Using the mdoel to design and evaluate interventions could result in a greater understanding of the mechanisms of c...

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

    NASA Astrophysics Data System (ADS)

    Jiang, Weimin

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

  1. Lower rotation speed stimulates sympathetic activation during continuous-flow left ventricular assist device treatment.

    PubMed

    Imamura, Teruhiko; Kinugawa, Koichiro; Nitta, Daisuke; Fujino, Takeo; Inaba, Toshiro; Maki, Hisataka; Hatano, Masaru; Kinoshita, Osamu; Nawata, Kan; Kyo, Shunei; Ono, Minoru

    2015-03-01

    Although the suppression of sympathetic activity is an essential mission for the current heart failure treatment strategy, little is known about the relationship between the rotation speed setting and autonomic nervous activity during continuous-flow left ventricular assist device (LVAD) treatment. We evaluated 23 adult patients with sinus rhythm (36 ± 13 years) who had received continuous-flow LVAD and been followed at our institute between March 2013 and August 2014. Heart rate variability measurement was executed along with hemodynamic study at 3 rotation speeds (low, middle, and high) at 5 weeks after LVAD implantation. Lower rotation speed was associated with higher ratio of low-frequency over high-frequency spectral level (LF/HF), representing enhanced sympathetic activation (p < 0.05 by repeated analyses of variance). Among hemodynamic parameters, cardiac index was exclusively associated with LFNU = LF/(LF + HF), representing relative sympathetic activity over parasympathetic one (p < 0.05). After 6 months LVAD support at middle rotation speed, 19 patients with higher LFNU eventually had higher plasma levels of B-type natriuretic peptide and achieved less LV reverse remodeling. A logistic regression analysis demonstrated that lower LFNU was significantly associated with improvement of LV reverse remodeling (p = 0.021, odds ratio 0.903) with a cut-off level of 55 % calculated by the ROC analysis (AUC 0.869). In conclusion, autonomic activity can vary in various rotation speeds. Patients with higher LFNU may better be controlled at higher rotation speed with the view point to suppress sympathetic activity and achieve LV reverse remodeling.

  2. Shape effect on the antibacterial activity of silver nanoparticles synthesized via a microwave-assisted method.

    PubMed

    Hong, Xuesen; Wen, Junjie; Xiong, Xuhua; Hu, Yongyou

    2016-03-01

    Silver nanoparticles (AgNPs) are used as sustained-release bactericidal agents for water treatment. Among the physicochemical characteristics of AgNPs, shape is an important parameter relevant to the antibacterial activity. Three typically shaped AgNPs, nanocubes, nanospheres, and nanowires, were prepared via a microwave-assisted method and characterized by TEM, UV-vis, and XRD. The antibacterial activity of AgNPs was determined by OD growth curves tests, MIC tests, and cell viability assay against Escherichia coli. The interaction between AgNPs and bacterial cells was observed by TEM. The results showed that the three differently shaped AgNPs were nanoscale, 55 ± 10 nm in edge length for nanocubes, 60 ± 15 nm in diameter for nanospheres, 60 ± 10 nm in diameter and 2-4 μm in length for nanowires. At the bacterial concentration of 10(4) CFU/mL, the MIC of nanocubes, nanospheres, and nanowires were 37.5, 75, and 100 μg/mL, respectively. Due to the worst contact with bacteria, silver nanowires exhibited the weakest antibacterial activity compared with silver nanocubes and silver nanospheres. Besides, silver nanocubes mainly covered by {100} facets showed stronger antibacterial activity than silver nanospheres covered by {111} facets. It suggests that the shape effect on the antibacterial activity of AgNPs is attributed to the specific surface areas and facets reactivity; AgNPs with larger effective contact areas and higher reactive facets exhibit stronger antibacterial activity.

  3. Condensed tannins from Ficus virens as tyrosinase inhibitors: structure, inhibitory activity and molecular mechanism.

    PubMed

    Chen, Xiao-Xin; Shi, Yan; Chai, Wei-Ming; Feng, Hui-Ling; Zhuang, Jiang-Xing; Chen, Qing-Xi

    2014-01-01

    Condensed tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark condensed tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the condensed tannins were studied. The results indicated that the condensed tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark condensed tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the condensed tannins on the diphenolase activity were further investigated. The results indicated that the condensed tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the condensed tannins could chelate the dicopper irons of the enzyme. Moreover, the condensed tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.

  4. Microwave assisted synthesis, cholinesterase enzymes inhibitory activities and molecular docking studies of new pyridopyrimidine derivatives.

    PubMed

    Basiri, Alireza; Murugaiyah, Vikneswaran; Osman, Hasnah; Kumar, Raju Suresh; Kia, Yalda; Ali, Mohamed Ashraf

    2013-06-01

    A series of hitherto unreported pyrido-pyrimidine-2-ones/pyrimidine-2-thiones were synthesized under microwave assisted solvent free reaction conditions in excellent yields and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibitory activity. Among the pyridopyrimidine derivatives, 7e and 7l displayed 2.5- and 1.5-fold higher enzyme inhibitory activities against AChE as compared to standard drug, galanthamine, with IC50 of 0.80 and 1.37 μM, respectively. Interestingly, all the compounds except 6k, 7j and 7k displayed higher inhibitory potential against BChE enzyme in comparison to standard with IC50 ranging from 1.18 to 18.90 μM. Molecular modeling simulations of 7e and 7l was performed using three-dimensional structure of Torpedo californica AChE (TcAChE) and human butyrylcholinesterase (hBChE) enzymes to disclose binding interaction and orientation of these molecule into the active site gorge of respective receptors.

  5. Ultrasound-Assisted Extraction, Antioxidant and Anticancer Activities of the Polysaccharides from Rhynchosia minima Root.

    PubMed

    Jia, Xuejing; Zhang, Chao; Hu, Jie; He, Muxue; Bao, Jiaolin; Wang, Kai; Li, Peng; Chen, Meiwan; Wan, Jianbo; Su, Huanxing; Zhang, Qingwen; He, Chengwei

    2015-01-01

    Box-Behnken design (BBD), one of the most common response surface methodology (RSM) methods, was used to optimize the experimental conditions for ultrasound-assisted extraction of polysaccharides from Rhynchosia minima root (PRM). The antioxidant abilities and anticancer activity of purified polysaccharide fractions were also measured. The results showed that optimal extraction parameters were as follows: ultrasound exposure time, 21 min; ratio of water to material, 46 mL/g; ultrasound extraction temperature, 63 °C. Under these conditions, the maximum yield of PRM was 16.95%±0.07%. Furthermore, the main monosaccharides of purified fractions were Ara and Gal. PRM3 and PRM5 exhibited remarkable DPPH radical scavenging activities and reducing power in vitro. PRM3 showed strong inhibitory activities on the growth of MCF-7 cells in vitro. The above results indicate that polysaccharides from R. minima root have the potential to be developed as natural antioxidants and anticancer ingredients for the food and pharmaceutical industries.

  6. Ultrasound-assisted enzymatic extraction and antioxidant activity of polysaccharides from pumpkin (Cucurbita moschata).

    PubMed

    Wu, Hao; Zhu, Junxiang; Diao, Wenchao; Wang, Chengrong

    2014-11-26

    An efficient ultrasound-assisted enzymatic extraction (UAEE) of Cucurbita moschata polysaccharides (CMCP) was established and the CMCP antioxidant activities were studied. The UAEE operating parameters (extraction temperature, ultrasonic power, pH, and liquid-to-material ratio) were optimized using the central composite design (CCD) and the mass transfer kinetic study in UAEE procedure was used to select the optimal extraction time. Enzymolysis and ultrasonication that were simultaneously conducted was selected as the UAEE synergistic model and the optimum extraction conditions with a maximum polysaccharide yield of 4.33 ± 0.15% were as follows: extraction temperature, 51.5 °C; ultrasonic power, 440 W; pH, 5.0; liquid-to-material ratio, 5.70:1 mL/g; and extraction time, 20 min. Evaluation of the antioxidant activity in vitro suggested that CMCP has good potential as a natural antioxidant used in the food or medicine industry because of their high reducing power and positive radical scavenging activity for DPPH radical.

  7. Ultrathin Palladium Membranes Prepared by a Novel Electric Field Assisted Activation

    SciTech Connect

    Yun, Samhun; Ko, Joon Ho; Oyama, S. Ted

    2011-03-01

    Ultra-thin Pd composite membranes with a thickness of 1 μm were prepared by a novel electric-field assisted activation technique followed by electroless deposition of Pd on a hollow-fiber α-alumina support. The novel activation method places Pd precursors and a reducing agent on opposite sides of a porous substrate and uses an electric field to cause migration of Pd ions to the outer surface where they are reduced to form seeds in high density in a narrow spatial region. The resulting membranes showed a high hydrogen permeance in the range of 4.0–5.0 × 10{sup −6} mol m{sup −2} s{sup −1} Pa{sup −1} and stable H{sub 2}/N{sub 2} selectivity of 3000–9000 during stability tests for 150 h at 733 K with H{sub 2} flow. The formation of the thin, defect-less and robust Pd layer can be ascribed to the evenly distributed Pd seeds on the support layer and the enhanced bonding between the Pd layer and the support layer resulting from the strong anchoring of the Pd seeds onto the support in the new activation step.

  8. Ultrasound-Assisted Extraction, Antioxidant and Anticancer Activities of the Polysaccharides from Rhynchosia minima Root.

    PubMed

    Jia, Xuejing; Zhang, Chao; Hu, Jie; He, Muxue; Bao, Jiaolin; Wang, Kai; Li, Peng; Chen, Meiwan; Wan, Jianbo; Su, Huanxing; Zhang, Qingwen; He, Chengwei

    2015-01-01

    Box-Behnken design (BBD), one of the most common response surface methodology (RSM) methods, was used to optimize the experimental conditions for ultrasound-assisted extraction of polysaccharides from Rhynchosia minima root (PRM). The antioxidant abilities and anticancer activity of purified polysaccharide fractions were also measured. The results showed that optimal extraction parameters were as follows: ultrasound exposure time, 21 min; ratio of water to material, 46 mL/g; ultrasound extraction temperature, 63 °C. Under these conditions, the maximum yield of PRM was 16.95%±0.07%. Furthermore, the main monosaccharides of purified fractions were Ara and Gal. PRM3 and PRM5 exhibited remarkable DPPH radical scavenging activities and reducing power in vitro. PRM3 showed strong inhibitory activities on the growth of MCF-7 cells in vitro. The above results indicate that polysaccharides from R. minima root have the potential to be developed as natural antioxidants and anticancer ingredients for the food and pharmaceutical industries. PMID:26610456

  9. Robot- and computer-assisted craniotomy (CRANIO): from active systems to synergistic man-machine interaction.

    PubMed

    Cunha-Cruz, V; Follmann, A; Popovic, A; Bast, P; Wu, T; Heger, S; Engelhardt, M; Schmieder, K; Radermacher, K

    2010-01-01

    Computer and robot assistance in craniotomy/craniectomy procedures is intended to increase precision and efficiency of the removal of calvarial tumours, enabling the preoperative design and manufacturing of the corresponding implant. In the framework of the CRANIO project, an active robotic system was developed to automate the milling processes based on a predefined resection planning. This approach allows for a very efficient milling process, but lacks feedback of the intra-operative process to the surgeon. To better integrate the surgeon into the process, a new teleoperated synergistic architecture was designed. This enables the surgeon to realize changes during the procedure and use their human cognitive capabilities. The preoperative planning information is used as guidance for the user interacting with the system through a master-slave architecture. In this article, the CRANIO system is presented together with this new synergistic approach. Experiments have been performed to evaluate the accuracy of the system in active and synergistic modes for the bone milling procedure. The laboratory studies showed the general feasibility of the new concept for the selected medical procedure and determined the accuracy of the system. Although the integration of the surgeon partially reduces the efficiency of the milling process compared with a purely active (automatic) milling, it provides more feedback and flexibility to the user during the intra-operative procedure.

  10. Nox family NADPH oxidases: Molecular mechanisms of activation.

    PubMed

    Brandes, Ralf P; Weissmann, Norbert; Schröder, Katrin

    2014-11-01

    NADPH oxidases of the Nox family are important enzymatic sources of reactive oxygen species (ROS). Numerous homologue-specific mechanisms control the activity of this enzyme family involving calcium, free fatty acids, protein-protein interactions, intracellular trafficking, and posttranslational modifications such as phosphorylation, acetylation, or sumoylation. After a brief review on the classic pathways of Nox activation, this article will focus on novel mechanisms of homologue-specific activity control and on cell-specific aspects which govern Nox activity. From these findings of the recent years it must be concluded that the activity control of Nox enzymes is much more complex than anticipated. Moreover, depending on the cellular activity state, Nox enzymes are selectively activated or inactivated. The complex upstream signaling aspects of these events make the development of "intelligent" Nox inhibitors plausible, which selectively attenuate disease-related Nox-mediated ROS formation without altering physiological signaling ROS. This approach might be of relevance for Nox-mediated tissue injury in ischemia-reperfusion and inflammation and also for chronic Nox overactivation as present in cancer initiation and cardiovascular disease.

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

    NASA Astrophysics Data System (ADS)

    Banerjee, Shiladitya

    2014-03-01

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

  12. Mechanisms of active control in cylindrical fuselage structures

    NASA Technical Reports Server (NTRS)

    Silcox, R. J.; Lester, H. C.; Fuller, C. R.

    1987-01-01

    This paper summarizes ongoing efforts to understand and exploit active control techniques for low frequency noise suppression in aerospace applications. Analytical models are utilized in an effort to understand the mechanisms that govern noise transmission into acoustic spaces enclosed by lightweight structures and to examine the results of experimental implementations of active control schemes. Emphasis is placed on attaining global noise reductions using a minimum number of actuators rather than localized control over many subregions. This program has demonstrated the effect of synchrophasing and interface modal filtering, in limiting the modal density within the acoustic space, and how strong reactive effects may occur in two dimensional geometries. Finally, the performance of active control systems utilizing acoustic and vibration actuators is evaluated. Suppressions of 10 to 30 dB are demonstrated in practice, and performance is discussed in relation to the physical mechanisms and parameters of the system.

  13. Versatile retraction mechanics: Implant assisted en-masse retraction with a boot loop

    PubMed Central

    Philip, Pramod; Jose, Nidhin Philip

    2015-01-01

    The purpose of this paper is to explain the versatility offered by the use of arch wires with boot loops in retraction mechanics while taking direct anchorage from mini-screws. Materials and Methods: The materials include the mini screws placed at the appropriate location and retraction arches made of 0.019 X 0.025 SS with boot loops placed distal to the lateral incisors. Mini screw provides a stable anchorage for enmasse retraction of the anterior teeth with the help of a boot loop using sliding and/or loop mechanics. Results: The arch wires with boot loops have a definite advantage over the soldered/crimpable hooks because of the versatility it offers during the process of retraction. Conclusion: An innovative approach combining the advantages of absolute anchorage using mini implants and a retraction arch with boot loop is presented here. PMID:25821373

  14. Microfluidic-assisted atomic force microscopy for the mechanical characterization of soft biological materials

    NASA Astrophysics Data System (ADS)

    Mosier, Aaron P.

    Viable methods for bacterial biofilm remediation require a fundamental understanding of biofilm mechanical properties and their dependence on dynamic environmental conditions. Mechanical test data, quantifying elasticity or adhesion, may be used to perform physical modeling of biofilm behavior, thus enabling the development of novel remediation strategies. To achieve real-time, dynamic measurements of these properties, a novel analysis platform consisting of a microfluidic flowcell device has been designed and fabricated for in situ analysis using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The flowcell consists of microfluidic channels for biofilm establishment that are then converted into an open architecture, laminar flow channel for AFM measurement in a liquid environment. Computational fluid dynamics (CFD) was used to profile fluid conditions within the device during biofilm establishment. The validity of the AFM nanoindentation measurement mechanism was confirmed in the context of the system through the elastic characterization of several non-living reference materials. Force-mode AFM was used to measure the elastic properties of mature Pseudomonas aeruginosa PAO1 biofilms and observe a dynamic response to a chemical antagonist. Elastic moduli ranging from 0.58 to 2.61 kPa were determined for the mature biofilm, which fall within the range of moduli previously reported by optical, rheometric, and microindentation techniques. A modified version of the flowcell was employed to perform similar elastic characterization of mouse submandibular glands (SMGs), demonstrating the adaptability of the system to perform ex situ analyses of a broader set of biological materials. These results demonstrate the validity of the microfluidic flowcell system as an effective platform for future investigations of the mechanical and morphological response of biofilms and other soft biomaterials to dynamic environmental conditions.

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

    PubMed

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

    2016-04-12

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

  16. Structure and Mechanism of the Phosphotyrosyl Phosphatase Activator

    SciTech Connect

    Chao,Y.; Xing, Y.; Chen, Y.; Xu, Y.; Lin, Z.; Li, Z.; Jeffrey, P.; Stock, J.; Shi, Y.

    2006-01-01

    Phosphotyrosyl phosphatase activator (PTPA), also known as PP2A phosphatase activator, is a conserved protein from yeast to human. Here we report the 1.9 {angstrom} crystal structure of human PTPA, which reveals a previously unreported fold consisting of three subdomains: core, lid, and linker. Structural analysis uncovers a highly conserved surface patch, which borders the three subdomains, and an associated deep pocket located between the core and the linker subdomains. The conserved surface patch and the deep pocket are responsible for binding to PP2A and ATP, respectively. PTPA and PP2A A-C dimer together constitute a composite ATPase. PTPA binding to PP2A results in a dramatic alteration of substrate specificity, with enhanced phosphotyrosine phosphatase activity and decreased phosphoserine phosphatase activity. This function of PTPA strictly depends on the composite ATPase activity. These observations reveal significant insights into the function and mechanism of PTPA and have important ramifications for understanding PP2A function.

  17. Study of InN nanorods growth mechanism using ultrathin Au layer by plasma-assisted MBE on Si(111)

    NASA Astrophysics Data System (ADS)

    Kumar, Mahesh; Rajpalke, Mohana K.; Roul, Basanta; Bhat, Thirumaleshwara N.; Krupanidhi, S. B.

    2014-01-01

    InN nanorods (NRs) were grown on Si(111) substrate by plasma-assisted molecular beam epitaxy. The growth of InN NRs has been demonstrated using an electron-beam evaporated (~2 nm) Au layer prior to the initiation of growth. The structure and morphology of as deposited Au film, annealed at 600 °C, and InN NRs were investigated using X-ray photoelectron spectroscopy and scanning electron microscopy. Chemical characterization was performed with energy dispersive X-ray analysis. Single-crystalline wurtzite structure of InN NRs is verified by transmission electron microscopy. The formation process of NRs is investigated and a qualitative mechanism is proposed.

  18. Ultrasound-assisted extraction of polysaccharides from Artemisia selengensis Turcz and its antioxidant and anticancer activities.

    PubMed

    Wang, Juan; Lu, He Dong; Muḥammad, Umair; Han, Jin Zhi; Wei, Zhao Hui; Lu, Zhao Xin; Bie, Xiao Mei; Lu, Feng Xia

    2016-02-01

    Artemisia selengensis Turcz (AST) is a perennial herb with therapeutic and economic applications in China. The effects of ultrasound-assisted extraction (UAE) parameters upon extraction yield (EY%), antioxidant and antitumor activities of the polysaccharides extracts were studied by using a factorial design and response surface methodology. The optimal conditions determined were as: ultrasonic power 146 W, extraction time 14.5 min. and extraction temperature 60 °C. The average molecular weights of two homogeneous polysaccharides (APS1 and APS2) purified by DEAE cellulose-52 and Sephadex G-100 column chromatography were 125.4 and 184.1 kDa, respectively. Monosaccharide analysis showed that APS1 and APS2 were composed of five common monomers i.e., galactose, mannose, arabinose, xylose and rhamnose and one different monomer glucose and galacturonic acid respectively, with a most abundant part in molar % of APS1 and APS2 were glucose (83.01 %) and galacturonic acid (48.87 %) while least were xylose (0.80 %) and mannose (1.73 %) respectively. The antioxidant properties were determined by evaluating DPPH, hydroxyl radical scavenging activity and reducing power which indicated both APS1 and APS2 showed strong scavenging activities and anticancer activities on HT-29, BGC823 and antitumor activity on HepG-2. As UAE improved the polysaccharides yield than CSE, meanwhile, no significant difference of polysaccharides chemical compositions. Therefore, the present study suggests that the consumption of AST leaves may beneficial for the treatment of many diseases. PMID:27162382

  19. Assessment of two immobilized lipases activity and stability to low temperatures in organic solvents under ultrasound-assisted irradiation.

    PubMed

    Batistella, Luciane; Ustra, Mara K; Richetti, Aline; Pergher, Sibele B C; Treichel, Helen; Oliveira, J V; Lerin, Lindomar; de Oliveira, Débora

    2012-03-01

    Both stability and catalytic activity of two commercial immobilized lipases were investigated in the presence of different organic solvents in ultrasound-assisted system. In a general way, for Novozym 435, the use of ethanol as solvent led to a loss of activity of 35% after 10 h of contact. The use of iso-octane conducted to a gradual increase in lipase activity in relation to the contact time, reaching a maximum value of relative activity of 126%. For Lipozyme RM IM, after 5 h of exposure, the enzyme presented no residual activity when ethanol was used as solvent. The solvents tert-butanol and iso-octane showed an enhancement of about 20 and 17% in the enzyme activity in 6 h of exposure, respectively. Novozym 435 and Lipozyme IM presented high stability to storage after treatment under ultrasound-assisted system using n-hexane and tert-butanol as solvents.

  20. Assessment of two immobilized lipases activity and stability to low temperatures in organic solvents under ultrasound-assisted irradiation.

    PubMed

    Batistella, Luciane; Ustra, Mara K; Richetti, Aline; Pergher, Sibele B C; Treichel, Helen; Oliveira, J V; Lerin, Lindomar; de Oliveira, Débora

    2012-03-01

    Both stability and catalytic activity of two commercial immobilized lipases were investigated in the presence of different organic solvents in ultrasound-assisted system. In a general way, for Novozym 435, the use of ethanol as solvent led to a loss of activity of 35% after 10 h of contact. The use of iso-octane conducted to a gradual increase in lipase activity in relation to the contact time, reaching a maximum value of relative activity of 126%. For Lipozyme RM IM, after 5 h of exposure, the enzyme presented no residual activity when ethanol was used as solvent. The solvents tert-butanol and iso-octane showed an enhancement of about 20 and 17% in the enzyme activity in 6 h of exposure, respectively. Novozym 435 and Lipozyme IM presented high stability to storage after treatment under ultrasound-assisted system using n-hexane and tert-butanol as solvents. PMID:21779888

  1. Development of a novel technique to assess the vulnerability of micro-mechanical system components to environmentally assisted cracking.

    SciTech Connect

    Enos, David George; Goods, Steven Howard

    2006-11-01

    Microelectromechanical systems (MEMS) will play an important functional role in future DOE weapon and Homeland Security applications. If these emerging technologies are to be applied successfully, it is imperative that the long-term degradation of the materials of construction be understood. Unlike electrical devices, MEMS devices have a mechanical aspect to their function. Some components (e.g., springs) will be subjected to stresses beyond whatever residual stresses exist from fabrication. These stresses, combined with possible abnormal exposure environments (e.g., humidity, contamination), introduce a vulnerability to environmentally assisted cracking (EAC). EAC is manifested as the nucleation and propagation of a stable crack at mechanical loads/stresses far below what would be expected based solely upon the materials mechanical properties. If not addressed, EAC can lead to sudden, catastrophic failure. Considering the materials of construction and the very small feature size, EAC represents a high-risk environmentally induced degradation mode for MEMS devices. Currently, the lack of applicable characterization techniques is preventing the needed vulnerability assessment. The objective of this work is to address this deficiency by developing techniques to detect and quantify EAC in MEMS materials and structures. Such techniques will allow real-time detection of crack initiation and propagation. The information gained will establish the appropriate combinations of environment (defining packaging requirements), local stress levels, and metallurgical factors (composition, grain size and orientation) that must be achieved to prevent EAC.

  2. Microstructure and Mechanical Properties of Ultrafine-Grained Copper Produced Using Intermittent Ultrasonic-Assisted Equal-Channel Angular Pressing

    NASA Astrophysics Data System (ADS)

    Lu, Jianxun; Wu, Xiaoyu; Liu, Zhiyuan; Chen, Xiaoqiang; Xu, Bin; Wu, Zhaozhi; Ruan, Shuangchen

    2016-09-01

    We proposed intermittent ultrasonic-assisted equal-channel angular pressing (IU-ECAP) and used it to produce ultrafine-grained copper. The main aim of this work was to investigate the microstructure and mechanical properties of copper processed by IU-ECAP. We performed experiments with two groups of specimens: group 1 used conventional ECAP, and group 2 combined ECAP with intermittent ultrasonic vibration. The extrusion forces, microstructure, mechanical properties, and thermal stability of the two groups were compared. It was revealed that more homogeneous microstructure with smaller grains could be obtained by IU-ECAP compared with copper obtained using the traditional ECAP method. Mechanical testing showed that IU-ECAP significantly reduced the extrusion force and increased both the hardness and ultimate tensile stress owing to the higher dislocation density and smaller grains. IU-ECAP promotes conversion from low-angle grain boundaries to high-angle grain boundaries, and it increases the fractions of subgrains and dynamic recrystallized grains. Group 2 statically recrystallized at a higher temperature or longer duration than group 1, showing that group 2 had better thermal stability.

  3. Assisted Living

    MedlinePlus

    ... Recreational activities Security Transportation How to Choose a Facility A good match between a facility and a resident's needs depends as much on the philosophy and services of the assisted living facility as it does on the quality of care. ...

  4. Does benign paroxysmal positional vertigo explain age and gender variation in patients with vertigo by mechanical assistance maneuvers?

    PubMed

    Wang, Jing; Chi, Fang-Lu; Jia, Xian-Hao; Tian, Liang; Richard-Vitton, Th

    2014-11-01

    Benign paroxysmal positional vertigo (BPPV) is one of the most common peripheral vestibular diseases. The aim of this study was to explore the prevalence of BPPV in vertigo patients and the characteristics of BPPV in diagnosis and repositioning using mechanical assistance maneuvers and to analyze and summarize the reasons showing these characteristics. Seven hundred and twenty-six patients with vertigo were enrolled in this study. All patients were inspected by TRV armchair (SYNAPSYS, model TRV, France). BPPV patients were identified by the examination results. The characteristics and results using TRV armchair in diagnosis and treatment of BPPV were compared and analyzed. Of 726 vertigo patients, 209 BPPV patients were diagnosed, including 58 men and 151 women, aged from 16 to 87 (mean 52.90 ± 11.93) years. There were significant differences in the proportion of BPPV in male and female vertigo patients (P = 0.0233), but no differences among all age groups (P = 0.3201). Of 209 BPPV patients, 208 cases were repositioned by TRV armchair and no one appeared to have otolithic debris relocated into another canal in the repositioning procedures. 202 cases (97.12 %) were successful and six cases (2.87 %) were effective. None of them failed. This study suggests that BPPV is one of the most common diseases in the young vertigo patients, just like that in the old ones. Female of the species has predilection for BPPV and the site of predilection is the right posterior semicircular canals (PC-BPPV). The results of repositioning are perfect using mechanical assistance maneuvers.

  5. Collaborative Storytelling Experiences in Social Media: Influence of Peer-Assistance Mechanisms

    ERIC Educational Resources Information Center

    Liu, Chen-Chung; Liu, Kuo-Ping; Chen, Wei-Hong; Lin, Chiu-Pin; Chen, Gwo-Dong

    2011-01-01

    Collaborative storytelling activities in social media environments are generally developed in a linear way in which all participants collaborate on a shared story as it is passed from one to another in a relay form. Difficulties with this linear approach arise when collecting the contributions of participants in to a coherent story. This study…

  6. Novel mechanisms for activated protein C cytoprotective activities involving noncanonical activation of protease-activated receptor 3.

    PubMed

    Burnier, Laurent; Mosnier, Laurent O

    2013-08-01

    The direct cytoprotective activities of activated protein C (APC) on cells convey therapeutic, relevant, beneficial effects in injury and disease models in vivo and require the endothelial protein C receptor (EPCR) and protease activated receptor 1 (PAR1). Thrombin also activates PAR1, but its effects on cells contrast APC's cytoprotective effects. To gain insights into mechanisms for these contrasting cellular effects, protease activated receptor 3 (PAR3) activation by APC and thrombin was studied. APC cleaved PAR3 on transfected and endothelial cells in the presence of EPCR. Remarkably, APC cleaved a synthetic PAR3 N-terminal peptide at Arg41, whereas thrombin cleaved at Lys38. On cells, APC failed to cleave R41Q-PAR3, whereas K38Q-PAR3 was still cleaved by APC but not by thrombin. PAR3 tethered-ligand peptides beginning at amino acid 42, but not those beginning at amino acid 39, conveyed endothelial barrier-protective effects. In vivo, the APC-derived PAR3 tethered-ligand peptide, but not the thrombin-derived PAR3 peptide, blunted vascular endothelial growth factor (VEGF)-induced vascular permeability. These data indicate that PAR3 cleavage by APC at Arg41 can initiate distinctive APC-like cytoprotective effects. These novel insights help explain the differentiation of APC's cytoprotective versus thrombin's proinflammatory effects on cells and suggest a unique contributory role for PAR3 in the complex mechanisms underlying APC cytoprotective effects. PMID:23788139

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

    NASA Astrophysics Data System (ADS)

    Severinov, Konstantin; Semenova, Ekaterina; Kazakov, Teymur

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

  8. Multivariable Static Ankle Mechanical Impedance With Active Muscles.

    PubMed

    Lee, Hyunglae; Ho, Patrick; Rastgaar, Mohammad; Krebs, Hermano Igo; Hogan, Neville

    2014-01-01

    This paper reports quantification of multivariable static ankle mechanical impedance when muscles were active. Repetitive measurements using a highly backdrivable therapeutic robot combined with robust function approximation methods enabled reliable characterization of the nonlinear torque-angle relation at the ankle in two coupled degrees of freedom simultaneously, a combination of dorsiflexion-plantarflexion and inversion-eversion, and how it varied with muscle activation. Measurements on 10 young healthy seated subjects quantified the behavior of the human ankle when muscles were active at 10% of maximum voluntary contraction. Stiffness, a linear approximation to static ankle mechanical impedance, was estimated from the continuous vector field. As with previous measurements when muscles were maximally relaxed, we found that ankle stiffness was highly direction-dependent, being weakest in inversion/eversion. Predominantly activating a single muscle or co-contracting antagonistic muscles significantly increased ankle stiffness in all directions but it increased more in the sagittal plane than in the frontal plane, accentuating the relative weakness of the ankle in the inversion-eversion direction. Remarkably, the observed increase was not consistent with simple superposition of muscle-generated stiffness, which may be due to the contribution of unmonitored deep ankle muscles. Implications for the assessment of neuro-mechanical disorders are discussed.

  9. Driving pressure during assisted mechanical ventilation: Is it controlled by patient brain?

    PubMed

    Georgopoulos, Dimitris; Xirouchaki, Nectaria; Tzanakis, Nikolaos; Younes, Magdy

    2016-07-01

    Tidal volume (VT) is the controlled variable during passive mechanical ventilation (CMV) in order to avoid ventilator-induced-lung-injury. However, recent data indicate that the driving pressure [ΔP; VT to respiratory system compliance (Crs) ratio] is the parameter that best stratifies the risk of death. In order to study which variable (VT or ΔP) is controlled by critically ill patients, 108 previously studied patients were assigned to receive PAV+ (a mode that estimates Crs and permits the patients to select their own breathing pattern) after CMV, were re-analyzed. When patients were switched from CMV to PAV+ they controlled ΔP without constraining VT to narrow limits. VT was increased when the resumption of spontaneous breathing was associated with an increase in Crs. When ΔP was high during CMV, the patients (n=12) decreased it in 58 out of 67 measurements. We conclude that critically ill patients control the driving pressure by sizing the tidal volume to individual respiratory system compliance using appropriate feedback mechanisms aimed at limiting the degree of lung stress.

  10. Forcing Open TRP channels: mechanical gating as a unifying activation mechanism

    PubMed Central

    Liu, Chao; Montell, Craig

    2015-01-01

    Transient receptor potential (TRP) proteins are cation channels that comprise a superfamily of molecular sensors that enable animals to detect a wide variety of environmental stimuli. This versatility enables vertebrate and invertebrate TRP channels to function in a diversity of senses, ranging from vision to taste, smell, touch, hearing, proprioception and thermosensation. Moreover, many individual TRP channels are activated through a surprising range of sensory stimuli. The multitasking nature of TRP channels raises the question as to whether seemingly disparate activators gate TRPs through common strategies. In this regard, a recent major advance is the discovery that a phospholipase C (PLC)-dependent signaling cascade activates the TRP channels in Drosophila photoreceptor cells through generation of force in the lipid-bilayer. The premise of this review is that mechanical force is a unifying, common strategy for gating TRP channels. In addition to several TRP channels that function in mechanosensation and are gated by force applied to the cells, changes in temperature and in the concentration of lipophilic second messengers through stimulation of signaling cascades, cause architectural modifications of the cell membrane, which in turn activate TRP channels through mechanical force. Consequently, TRPs are capable of functioning as stretch-activated channels, even in cases in which the stimuli that initiate the signaling cascades are not mechanical. We propose that most TRPs are actually mechanosensitive channels (MSCs), which undergo conformational changes in response to tension imposed on the lipid bilayer, resulting in channel gating. PMID:25998730

  11. Arthroscopic-Assisted Fixation of Tibial Plateau Fractures: Patient-Reported Postoperative Activity Levels.

    PubMed

    Kampa, John; Dunlay, Ryan; Sikka, Robby; Swiontkowski, Marc

    2016-05-01

    Tibial plateau fractures may result in significant limitations postoperatively. Studies have described outcomes of arthroscopic-assisted percutaneous fixation (AAPF) of these injuries but have rarely reported postoperative activity levels. Between 2009 and 2013, patients who sustained a lateral split, split depression, or pure depression type tibial plateau fracture (Schatzker types I-III fractures) and underwent outpatient AAPF were eligible for the study. Outcomes were assessed using Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Lysholm score, and Marx activity score. Twenty-five consecutive patients were eligible for the study, and 22 (88%) were included in the final analysis, with average follow-up of 2.5 years (range, 1-5.2 years). Thirteen women and 9 men with an average age of 48.3 years (range, 23-65 years) comprised the study population. Average number of screws used for fixation was 2 (range, 1-4). The average depression was 8 mm preoperatively and 0.9 mm (range, 0-3 mm) postoperatively. Four patients (18%) had complications: 2 with hardware removal and 2 with postoperative deep venous thrombosis. Average postoperative Marx activity score was 5.7. Average postoperative KOOS Symptoms, Sports, and Quality of Life scores were 88 (range, 68-100), 85 (range, 45-100), and 77 (range, 50-100), respectively. Average IKDC and Lysholm scores were 81 (range, 55-97) and 87 (range, 54-100), respectively. The AAPF surgical technique, which was performed in an outpatient setting, facilitated excellent postoperative range of motion, outcomes, and activity scores with minimal complications. [Orthopedics. 2016; 39(3):e486-e491.].

  12. Influence of Polarity and Activation Energy in Microwave-Assisted Organic Synthesis (MAOS).

    PubMed

    Rodríguez, Antonio M; Prieto, Pilar; de la Hoz, Antonio; Díaz-Ortiz, Ángel; Martín, D Raúl; García, José I

    2015-06-01

    The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20-30 kcal mol(-1) and a polarity (μ) between 7-20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation.

  13. Animal-Assisted Activities: Results From a Survey of Top-Ranked Pediatric Oncology Hospitals.

    PubMed

    Chubak, Jessica; Hawkes, Rene

    2016-07-01

    Animal-assisted activities (AAA) are increasingly common, yet little is known about practices in pediatric oncology. To address this gap, we surveyed the top 20 pediatric oncology hospitals in the United States in May and June of 2014. Questionnaires were sent via e-mail and generally returned by e-mail or postal mail. Among the 19 responding hospitals, the 18 that offered AAA to pediatric patients formed the basis of our analysis. All sites had written AAA policies. Most programs were restricted to dogs. At 11 hospitals, children with cancer could participate in AAA activities. Outpatient waiting rooms and individual inpatient rooms were the most common locations for AAA with pediatric oncology patients. Safety precautions varied by hospital, but all required hand sanitation after visits and that animals receive an annual health examination, be on a leash or in a carrier, be ≥1 year old, and not be directly from a shelter. Our findings reveal consistencies and variations in practice that may help other hospitals develop their own programs and researchers identify areas of future study.

  14. Influence of Polarity and Activation Energy in Microwave–Assisted Organic Synthesis (MAOS)

    PubMed Central

    Rodríguez, Antonio M; Prieto, Pilar; de la Hoz, Antonio; Díaz-Ortiz, Ángel; Martín, D Raúl; García, José I

    2015-01-01

    The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20–30 kcal mol−1 and a polarity (μ) between 7–20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation. PMID:26246993

  15. Effects of Animal-Assisted Activities with Guinea Pigs in the Primary School Classroom

    PubMed Central

    O’Haire, Marguerite E.; McKenzie, Samantha J.; McCune, Sandra; Slaughter, Virginia

    2013-01-01

    This study investigated the effects of a classroom-based animal-assisted activities (AAA) program with guinea pigs on the social functioning of primary school children. We hypothesized that participants in the experimental condition (n = 64), compared with a waitlist control group (n = 64), would demonstrate improvements in social functioning following the program. Parents and teachers used the Social Skills Rating System (SSRS) to evaluate the social skills and problem behaviors of 128 participating children (age range = 4.8 to 12.7 years) before and after an 8-week period. Teachers also rated academic competence at both time points. Children who participated in the AAA program demonstrated significantly greater improvements in social functioning than their control group peers, as defined by greater increases in social skills (teacher SSRS) and decreases in problem behaviors (parent and teacher SSRS). There were no significant differences between the groups in academic competence. AAA participants demonstrated significant increases in social skills and decreases in problem behaviors from pre- to post-program on the teacher version of the SSRS. Control group participants did not show significant changes on these measures. These findings suggest that an AAA program with guinea pigs may be a feasible addition to the primary school classroom in order to improve social functioning. Further component analysis will be necessary to determine whether the animal is the active ingredient in AAA programs of this nature. PMID:24265514

  16. Optimization of enzyme-assisted extraction of polysaccharides from alfalfa and its antioxidant activity.

    PubMed

    Wang, Shaopu; Dong, Xiaofang; Tong, Jianming

    2013-11-01

    In this present study, an efficient complex enzyme-assisted extraction technology was developed and optimized to extract polysaccharides from alfalfa using four factors at five levels central composite rotatable response surface design (CCRD). The experimental data was fitted to a second order polynomial equation with high coefficient of determination values (R(2)>0.95). The results of statistical analysis showed that the linear and quadratic terms of these four variables had significant effects (P<0.05) on the yield of polysaccharides from alfalfa. The optimum conditions were as follows: enzyme concentration of 2.5%, 2.0%, 3.0% (weight of alfalfa) of cellulase, papain and pectase, extraction temperature 52.7 °C, extraction pH 3.87, ratio of water to raw material 78.92 mL/g and extraction time 2.73 h. Under the optimal conditions, the experimental extraction yield of alfalfa polysaccharides was 5.05 ± 0.02%, which was well matched with the value (5.09%) predicted by the CCRD model. Moreover, evaluation of the antioxidant activity of polysaccharides from alfalfa in vitro suggested that the polysaccharides had good antioxidant effect, especially scavenging activity for hydroxyl radical and DPPH radical, which indicated that the polysaccharides from alfalfa may be explored as a novel natural antioxidant.

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

    DOEpatents

    Munir, Zuhair A.; Woolman, Joseph N.; Petrovic, John J.

    2003-09-02

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

  18. Atom-assisted quadrature squeezing of a mechanical oscillator inside a dispersive cavity

    NASA Astrophysics Data System (ADS)

    Chauhan, Anil Kumar; Biswas, Asoka

    2016-08-01

    We present a hybrid optomechanical scheme to achieve dynamical squeezing of position quadrature of a mesoscopic mechanical oscillator, that can be externally controlled by classical fields. A membrane-in-the-middle setup is employed, in which an atom in Λ configuration is considered to be trapped on either side of the membrane inside the cavity. We show that a considerable amount of squeezing (beyond the 3-dB limit) can be achieved and maintained at a transient time scale that is not affected by the spontaneous emission of the atom. Squeezing depends upon the initial preparation of atomic states. Further, a strong effective coupling (larger than the relevant decay rates) between the atom and the oscillator can be attained by using large control fields that pump the atom and the cavity. The effects of cavity decay and the phononic bath on squeezing are studied. The results are supported by the detailed analytical calculations.

  19. Mechanism of silver(I)-assisted growth of gold nanorods and bipyramids.

    PubMed

    Liu, Mingzhao; Guyot-Sionnest, Philippe

    2005-12-01

    The seed-mediated growth of gold nanostructures is shown to be strongly dependent on the gold seed nanocrystal structure. The gold seed solutions can be prepared such that the seeds are either single crystalline or multiply twinned. With added silver(I) in the cetyltrimethylammonium bromide (CTAB) aqueous growth solutions, the two types of seeds yield either nanorods or elongated bipyramidal nanoparticles, in good yields. The gold nanorods are single crystalline, with a structure similar to those synthesized electrochemically (Yu, Y. Y. et al. J. Phys. Chem. B 1997, 101, 6661). In contrast, the gold bipyramids are pentatwinned. These bipyramids are strikingly monodisperse in shape. This leads to the sharpest ensemble longitudinal plasmon resonance reported so far for metal colloid solutions, with an inhomogeneous width as narrow as 0.13 eV for a resonance at approximately 1.5 eV. Ag(I) plays an essential role in the growth mechanism. Ag(I) slows down the growth of the gold nanostructures. Ag(I) also leads to high-energy side facets that are {110} for the single crystalline gold nanorods and unusually highly stepped {11n} (n approximately 7) for the bipyramid. To rationalize these observations, it is proposed that it is the underpotential deposition of Ag(I) that leads to the dominance of the facets with the more open surface structures. This forms the basis for the one-dimensional growth mechanism of single crystal nanorods, while it affects the shape of the nanostructures growing along a single twinning axis. PMID:16853888

  20. Oocyte activation and phospholipase C zeta (PLCζ): diagnostic and therapeutic implications for assisted reproductive technology

    PubMed Central

    2012-01-01

    Infertility affects one in seven couples globally and has recently been classified as a disease by the World Health Organisation (WHO). While in-vitro fertilisation (IVF) offers effective treatment for many infertile couples, cases exhibiting severe male infertility (19–57%) often remain difficult, if not impossible to treat. In such cases, intracytoplasmic sperm injection (ICSI), a technique in which a single sperm is microinjected into the oocyte, is implemented. However, 1–5% of ICSI cycles still fail to fertilise, affecting over 1000 couples per year in the UK alone. Pregnancy and delivery rates for IVF and ICSI rarely exceed 30% and 23% respectively. It is therefore imperative that Assisted Reproductive Technology (ART) protocols are constantly modified by associated research programmes, in order to provide patients with the best chances of conception. Prior to fertilisation, mature oocytes are arrested in the metaphase stage of the second meiotic division (MII), which must be alleviated to allow the cell cycle, and subsequent embryogenesis, to proceed. Alleviation occurs through a series of concurrent events, collectively termed ‘oocyte activation’. In mammals, oocytes are activated by a series of intracellular calcium (Ca2+) oscillations following gamete fusion. Recent evidence implicates a sperm-specific phospholipase C, PLCzeta (PLCζ), introduced into the oocyte following membrane fusion as the factor responsible. This review summarises our current understanding of oocyte activation failure in human males, and describes recent advances in our knowledge linking certain cases of male infertility with defects in PLCζ expression and activity. Systematic literature searches were performed using PubMed and the ISI-Web of Knowledge. Databases compiled by the United Nations and World Health Organisation databases (UNWHO), and the Human Fertilization and Embryology Authority (HFEA) were also scrutinised. It is clear that PLCζ plays a fundamental role in

  1. Active Assistance Technology for Health-Related Behavior Change: An Interdisciplinary Review

    PubMed Central

    Kennedy, Catriona M; Powell, John; Payne, Thomas H; Ainsworth, John; Boyd, Alan

    2012-01-01

    dialog systems for behavior change, with many pilot studies showing a preference for those features. We found few studies that focused on interactive education (3 studies) and self-monitoring (2 studies). Some recent research is emerging in dynamic tailoring (15 studies) and theoretically grounded ontologies for automated semantic processing (4 studies). Conclusions The potential capabilities and risks of active assistance technologies are not being fully explored in most current behavior change research. Designers of health behavior interventions need to consider the relevant informatics methods and algorithms more fully. There is also a need to analyze the possibilities that can result from interaction between different technology components. This requires deep interdisciplinary collaboration, for example, between health psychology, computer science, health informatics, cognitive science, and educational methodology. PMID:22698679

  2. Potentiation of antidepressant-like activity with lithium: mechanism involved.

    PubMed

    Chenu, Franck; Bourin, Michel

    2006-02-01

    In the last decade, many augmentation strategies have been developed to increase the activity of antidepressant drugs or to reduce their long onset of action by acting on different targets. One of the first augmentation strategy used in psychiatric disorders is coadministration of lithium and antidepressant drugs. However, the underlaying mechanism of action involved in the potentiatory effect of lithium is still unclear and many hypotheses have been suggested such as activity on BDNF, ACTH, thyroid hormones and serotonin neurotransmission. All these systems being embedded in each other, we focused on the 5-HT neurotransmission-increase induced by lithium treatment. Based on neurobiochemical and behavioral results we tried to better understand its mechanism of action and we concluded that effect of lithium on 5-HT neurotransmission could be linked to a partial agonist activity on 5-HT1B autoreceptors, or to a modulatory activity on these receptors, located in the cortical area in the case of a short term treatment, or in the hippocampus in the case of a long term treatment. We also suggested that the anti-manic effect of lithium was linked to this activity on 5-HT1B receptors, occurring this time on 5-HT1B postsynaptic (heteroreceptors on dopaminergic pathways) receptors levels.

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

    NASA Astrophysics Data System (ADS)

    Rao, M.

    2014-07-01

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

  4. The activity-stress paradigm: possible mechanisms and applications.

    PubMed

    Lambert, K G

    1993-01-01

    The mechanisms and applications of the activity-stress (A-S) research paradigm are examined in this article. Past research has reflected the value of this paradigm in the investigation of ulcerogenesis. Evidence is offered to support a theory explaining the excessive running observed in the A-S animals, according to which, animals commence running to increase body temperature after failing to adapt to the restricted feeding regime. Further, excessive running levels are hypothesized to be sustained by reinforcement resulting from increased mesolimbic dopaminergic activity. Finally, parallels between the behavior observed in the A-S animals and some forms of maladaptive behavior observed in humans are discussed.

  5. Workability and mechanical properties of alkali activated slag concrete

    SciTech Connect

    Collins, F.G.; Sanjayan, J.G.

    1999-03-01

    This paper reports the results of an investigation on concrete containing alkali activated slag (AAS) as the binder, with emphasis on achievement of reasonable workability and equivalent one-day strength to portland cement concrete at normal curing temperatures. Two types of activators were used: sodium hydroxide in combination with sodium carbonate and sodium silicate in combination with hydrated lime. The fresh concrete properties reported include slump and slump loss, air content, and bleed. Mechanical properties of AAS concrete, including compressive strength, elastic modulus, flexural strength, drying shrinkage, and creep are contrasted with those of portland cement concrete.

  6. About mechanisms of tetonic activity of the satellites

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.

    2003-04-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  9. Degradation kinetics and mechanism of aniline by heat-assisted persulfate oxidation.

    PubMed

    Xie, Xiaofang; Zhang, Yongqing; Huang, Weilin; Huang, Shaobing

    2012-01-01

    Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system (pH 3), while a high degradation rate was achieved at strong alkalinity (pH 11). Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity (pH 5, 7 and 9). Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4'-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.

  10. 34 CFR 350.19 - What must a grantee do in carrying out a technical assistance activity?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 2 2014-07-01 2013-07-01 true What must a grantee do in carrying out a technical assistance activity? 350.19 Section 350.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF...

  11. 34 CFR 350.19 - What must a grantee do in carrying out a technical assistance activity?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false What must a grantee do in carrying out a technical assistance activity? 350.19 Section 350.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF...

  12. 34 CFR 350.19 - What must a grantee do in carrying out a technical assistance activity?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 2 2011-07-01 2010-07-01 true What must a grantee do in carrying out a technical assistance activity? 350.19 Section 350.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF...

  13. 34 CFR 350.19 - What must a grantee do in carrying out a technical assistance activity?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 2 2012-07-01 2012-07-01 false What must a grantee do in carrying out a technical assistance activity? 350.19 Section 350.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF...

  14. 34 CFR 350.19 - What must a grantee do in carrying out a technical assistance activity?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 2 2013-07-01 2013-07-01 false What must a grantee do in carrying out a technical assistance activity? 350.19 Section 350.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF...

  15. Examining Success of Communication Strategies Used by Formal Caregivers Assisting Individuals with Alzheimer's Disease during an Activity of Daily Living

    ERIC Educational Resources Information Center

    Wilson, Rozanne; Rochon, Elizabeth; Mihailidis, Alex; Leonard, Carol

    2012-01-01

    Purpose: To examine how formal (i.e., employed) caregivers' use verbal and nonverbal communication strategies while assisting individuals with moderate to severe Alzheimer's disease (AD) during the successful completion of an activity of daily living (ADL). Based on the literature, the authors hypothesized that caregivers' use of 1 proposition,…

  16. Part 106--Nondiscrimination on the Basis of Sex in Education Programs or Activities Receiving Federal Financial Assistance.

    ERIC Educational Resources Information Center

    Office for Civil Rights (ED), Washington, DC.

    This document addresses nondiscrimination on the basis of sex in education programs or activities receiving federal financial assistance. It includes the amendments made in the notice of Final Regulations published in the Federal Register on November 13, 2000. The amendments effectuate Title IX of the Education Amendments of 1972. The official…

  17. Investigating the Efficacy of a Computerized Prompting Device to Assist Children with Autism Spectrum Disorder with Activities of Daily Living

    ERIC Educational Resources Information Center

    Bimbrahw, Justin; Boger, Jennifer; Mihailidis, Alex

    2012-01-01

    Learning to perform self-care skills can pose a major challenge for children with Autism Spectrum Disorder (ASD) as well as the parents and caregivers who support them. The computerized device described in this paper has been used by children with ASD and their carers to autonomously assist with self-care activities. The device uses computer…

  18. 77 FR 75362 - Nondiscrimination in Federally Assisted Programs or Activities of SBA-Effectuation of the Age...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-20

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION 13 CFR Part 117 Nondiscrimination in Federally Assisted Programs or Activities of SBA--Effectuation of the Age Discrimination Act of 1975, as Amended CFR Correction 0 In Title 13 of the Code...

  19. 34 CFR 403.140 - What activities does the Secretary support under the State Assistance for Vocational Education...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... VOCATIONAL AND ADULT EDUCATION, DEPARTMENT OF EDUCATION STATE VOCATIONAL AND APPLIED TECHNOLOGY EDUCATION... 34 Education 3 2010-07-01 2010-07-01 false What activities does the Secretary support under the State Assistance for Vocational Education Support Programs by Community-Based Organizations?...

  20. Task Lists for Health Occupations. Radiologic Aide. Activity Aide. Optometric Assistant. Physical Therapy Aide. Education for Employment Task Lists.

    ERIC Educational Resources Information Center

    Lathrop, Janice

    These task lists contain employability skills and tasks for the following health occupations: radiologic aide, activity aide, physical therapy aide, and optometric assistant. The duties and tasks found in these lists form the basis of instructional content for secondary, postsecondary, and adult occupational training programs. Employability skills…

  1. A new technique for determining proper mechanical axis alignment during total knee arthroplasty: progress toward computer-assisted TKA.

    PubMed

    Krackow, K A; Bayers-Thering, M; Phillips, M J; Bayers-Thering, M; Mihalko, W M

    1999-07-01

    Successful total knee arthroplasty (TKA) relies on proper positioning of prosthetic components to restore the mechanical axis of the lower extremity. This report presents and analyzes a new noninvasive method using the Optotrack (Northern Digital Inc, Ontario, Canada) to accurately determine the center of the femoral head. This method, together with direct digitization of the bony landmarks of the knee and ankle intraoperatively, permits placement of the lower extremity in proper alignment intraoperatively. It also permits the surgeon to follow all the angles of movement or rotation and all displacements that occur at each step of the operative procedure. knee intraoperatively via a customized Windows-based program. In addition to presenting our first case, which, importantly, represents the first computer-assisted TKA in a patient, we report on the accuracy and reproducibility of the technique for locating the center of the femoral head obtained during an extensive series of cadaver studies. Location of the femoral head, a major aspect of effecting neutral mechanical axis alignment, appears to be possible to within 2-4 mm, which corresponds to an angular accuracy of better than 1 degree. This method requires no computed tomography scans or other preliminary marker placement. The only basic requirement other than the instrumentation described is a freely mobile hip, which is generally present in TKA patients. PMID:10418867

  2. Investigations in physical mechanism of the oxidative desulfurization process assisted simultaneously by phase transfer agent and ultrasound.

    PubMed

    Bhasarkar, Jaykumar B; Chakma, Sankar; Moholkar, Vijayanand S

    2015-05-01

    This paper attempts to discern the physical mechanism of the oxidative desulfurization process simultaneously assisted by ultrasound and phase transfer agent (PTA). With different experimental protocols, an attempt is made to deduce individual beneficial effects of PTA and ultrasound on the oxidative desulfurization system, and also the synergy between the effects of PTA and ultrasound. Effect of PTA is more marked for mechanically stirred system due to mass transfer limitations, while intense emulsification due to ultrasound helps overcome the mass transfer limitations and reduces the extent of enhancement of oxidation by PTA. Despite application of PTA and ultrasound, the intrinsic factors and properties of the reactants such as polarity (and hence partition coefficient) and diffusivity have a crucial effect on the extent of oxidation. The intrinsic reactivity of the oxidant also plays a vital role, as seen from the extent of oxidation achieved with performic acid and peracetic acid. The interfacial transport of oxidant in the form of oxidant-PTA complex reduces the undesired consumption of oxidant by the reducing species formed during transient cavitation in organic medium, which helps effective utilization of oxidant towards desulfurization. PMID:25465876

  3. High active nitrogen flux growth of GaN by plasma assisted molecular beam epitaxy

    SciTech Connect

    McSkimming, Brian M. Speck, James S.; Chaix, Catherine

    2015-09-15

    In the present study, the authors report on a modified Riber radio frequency (RF) nitrogen plasma source that provides active nitrogen fluxes more than 30 times higher than those commonly used for plasma assisted molecular beam epitaxy (PAMBE) growth of gallium nitride (GaN) and thus a significantly higher growth rate than has been previously reported. GaN films were grown using N{sub 2} gas flow rates between 5 and 25 sccm while varying the plasma source's RF forward power from 200 to 600 W. The highest growth rate, and therefore the highest active nitrogen flux, achieved was ∼7.6 μm/h. For optimized growth conditions, the surfaces displayed a clear step-terrace structure with an average RMS roughness (3 × 3 μm) on the order of 1 nm. Secondary ion mass spectroscopy impurity analysis demonstrates oxygen and hydrogen incorporation of 1 × 10{sup 16} and ∼5 × 10{sup 17}, respectively. In addition, the authors have achieved PAMBE growth of GaN at a substrate temperature more than 150 °C greater than our standard Ga rich GaN growth regime and ∼100 °C greater than any previously reported PAMBE growth of GaN. This growth temperature corresponds to GaN decomposition in vacuum of more than 20 nm/min; a regime previously unattainable with conventional nitrogen plasma sources. Arrhenius analysis of the decomposition rate shows that samples with a flux ratio below stoichiometry have an activation energy greater than decomposition of GaN in vacuum while samples grown at or above stoichiometry have decreased activation energy. The activation energy of decomposition for GaN in vacuum was previously determined to be ∼3.1 eV. For a Ga/N flux ratio of ∼1.5, this activation energy was found to be ∼2.8 eV, while for a Ga/N flux ratio of ∼0.5, it was found to be ∼7.9 eV.

  4. Mechanism of Procaspase-8 Activation by c-FLIPL

    SciTech Connect

    Yu, J.; Jeffrey, P; Shi, Y

    2009-01-01

    Cellular FLICE-inhibitory protein (c-FLIPL) is a key regulator of the extrinsic cell death pathway. Although widely regarded as an inhibitor of initiator caspase activation and cell death, c-FLIPL is also capable of enhancing procaspase-8 activation through heterodimerization of their respective protease domains. However, the underlying mechanism of this activation process remains enigmatic. Here, we demonstrate that cleavage of the intersubunit linker of c-FLIPL by procaspase-8 potentiates the activation process by enhancing heterodimerization between the two proteins and vastly improving the proteolytic activity of unprocessed caspase-(C)8. The crystal structures of the protease-like domain of c-FLIPL alone and in complex with zymogen C8 identify the unique determinants that favor heterodimerization over procaspase-8 homodimerization, and induce the latent active site of zymogen C8 into a productive conformation. Together, these findings provide molecular insights into a key aspect of c-FLIPL function that modulates procaspase-8 activation to elicit diverse responses in different cellular contexts.

  5. Mechanically Robust Plasma-Activated Interfaces Optimized for Vascular Stent Applications.

    PubMed

    Santos, Miguel; Filipe, Elysse C; Michael, Praveesuda L; Hung, Juichien; Wise, Steven G; Bilek, Marcela M M

    2016-04-20

    The long-term performance of many medical implants is limited by the use of inherently incompatible and bioinert materials. Metallic alloys, ceramics, and polymers commonly used in cardiovascular devices encourage clot formation and fail to promote the appropriate molecular signaling required for complete implant integration. Surface coating strategies have been proposed for these materials, but coronary stents are particularly problematic as the large surface deformations they experience in deployment require a mechanically robust coating interface. Here, we demonstrate a single-step ion-assisted plasma deposition process to tailor plasma-activated interfaces to meet current clinical demands for vascular implants. Using a process control-feedback strategy which predicts crucial coating growth mechanisms by adopting a suitable macroscopic plasma description in combination with noninvasive plasma diagnostics, we describe the optimal conditions to generate highly reproducible, industry-scalable stent coatings. These interfaces are mechanically robust, resisting delamination even upon plastic deformation of the underlying material, and were developed in consideration of the need for hemocompatibility and the capacity for biomolecule immobilization. Our optimized coating conditions combine the best mechanical properties with strong covalent attachment capacity and excellent blood compatibility in initial testing with plasma and whole blood, demonstrating the potential for improved vascular stent coatings. PMID:27015083

  6. 78 FR 14517 - Agency Information Collection Activities; Comment Request; Technical Assistance To Promote the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... Implementation of Re-Engagement Centers for Out-of-School Youth AGENCY: Office of Elementary and Secondary... Assistance to Promote the Implementation of Re-Engagement Centers for Out-of-school youth. OMB Control Number... Number ED-ESE-12-R-0102, ``Technical Assistance to Promote the Implementation of Re-Engagement...

  7. Proteolytic activation defines distinct lymphangiogenic mechanisms for VEGFC and VEGFD.

    PubMed

    Bui, Hung M; Enis, David; Robciuc, Marius R; Nurmi, Harri J; Cohen, Jennifer; Chen, Mei; Yang, Yiqing; Dhillon, Veerpal; Johnson, Kathy; Zhang, Hong; Kirkpatrick, Robert; Traxler, Elizabeth; Anisimov, Andrey; Alitalo, Kari; Kahn, Mark L

    2016-06-01

    Lymphangiogenesis is supported by 2 homologous VEGFR3 ligands, VEGFC and VEGFD. VEGFC is required for lymphatic development, while VEGFD is not. VEGFC and VEGFD are proteolytically cleaved after cell secretion in vitro, and recent studies have implicated the protease a disintegrin and metalloproteinase with thrombospondin motifs 3 (ADAMTS3) and the secreted factor collagen and calcium binding EGF domains 1 (CCBE1) in this process. It is not well understood how ligand proteolysis is controlled at the molecular level or how this process regulates lymphangiogenesis, because these complex molecular interactions have been difficult to follow ex vivo and test in vivo. Here, we have developed and used biochemical and cellular tools to demonstrate that an ADAMTS3-CCBE1 complex can form independently of VEGFR3 and is required to convert VEGFC, but not VEGFD, into an active ligand. Consistent with these ex vivo findings, mouse genetic studies revealed that ADAMTS3 is required for lymphatic development in a manner that is identical to the requirement of VEGFC and CCBE1 for lymphatic development. Moreover, CCBE1 was required for in vivo lymphangiogenesis stimulated by VEGFC but not VEGFD. Together, these studies reveal that lymphangiogenesis is regulated by two distinct proteolytic mechanisms of ligand activation: one in which VEGFC activation by ADAMTS3 and CCBE1 spatially and temporally patterns developing lymphatics, and one in which VEGFD activation by a distinct proteolytic mechanism may be stimulated during inflammatory lymphatic growth. PMID:27159393

  8. Proteolytic activation defines distinct lymphangiogenic mechanisms for VEGFC and VEGFD

    PubMed Central

    Bui, Hung M.; Enis, David; Robciuc, Marius R.; Nurmi, Harri J.; Cohen, Jennifer; Chen, Mei; Yang, Yiqing; Dhillon, Veerpal; Johnson, Kathy; Zhang, Hong; Kirkpatrick, Robert; Traxler, Elizabeth; Alitalo, Kari

    2016-01-01

    Lymphangiogenesis is supported by 2 homologous VEGFR3 ligands, VEGFC and VEGFD. VEGFC is required for lymphatic development, while VEGFD is not. VEGFC and VEGFD are proteolytically cleaved after cell secretion in vitro, and recent studies have implicated the protease a disintegrin and metalloproteinase with thrombospondin motifs 3 (ADAMTS3) and the secreted factor collagen and calcium binding EGF domains 1 (CCBE1) in this process. It is not well understood how ligand proteolysis is controlled at the molecular level or how this process regulates lymphangiogenesis, because these complex molecular interactions have been difficult to follow ex vivo and test in vivo. Here, we have developed and used biochemical and cellular tools to demonstrate that an ADAMTS3-CCBE1 complex can form independently of VEGFR3 and is required to convert VEGFC, but not VEGFD, into an active ligand. Consistent with these ex vivo findings, mouse genetic studies revealed that ADAMTS3 is required for lymphatic development in a manner that is identical to the requirement of VEGFC and CCBE1 for lymphatic development. Moreover, CCBE1 was required for in vivo lymphangiogenesis stimulated by VEGFC but not VEGFD. Together, these studies reveal that lymphangiogenesis is regulated by two distinct proteolytic mechanisms of ligand activation: one in which VEGFC activation by ADAMTS3 and CCBE1 spatially and temporally patterns developing lymphatics, and one in which VEGFD activation by a distinct proteolytic mechanism may be stimulated during inflammatory lymphatic growth. PMID:27159393

  9. Optimization of enzyme assisted extraction of Fructus Mori polysaccharides and its activities on antioxidant and alcohol dehydrogenase.

    PubMed

    Deng, Qingfang; Zhou, Xin; Chen, Huaguo

    2014-10-13

    In the present study, enzyme assisted extraction of Fructus Mori polysaccharides (FMPS) from F. mori using four kinds of enzymes and three compound enzymes were examined. Research found that glucose oxidase offered a better performance in enhancement of the extraction yields of FMPS, antioxidant and activate alcohol dehydrogenase activities. The glucose oxidase assisted extraction process was further optimized by using response surface method (RSM) to obtain maximum yield of crude FMPS. The results showed that optimized extraction conditions were ratio of enzyme amount 0.40%, enzyme treated time 38 min, treated temperature 58 °C and liquid-solid radio 11.0. Under these conditions, the mean experimental value of extraction yield (16.16 ± 0.14%) corresponded well with the predicted values and increased 160% than none enzyme treated ones. Pharmacological verification tests showed that F. mori crude polysaccharides had good antioxidant and activate alcohol dehydrogenase activities in vitro. PMID:25037415

  10. Optimization of enzyme assisted extraction of Fructus Mori polysaccharides and its activities on antioxidant and alcohol dehydrogenase.

    PubMed

    Deng, Qingfang; Zhou, Xin; Chen, Huaguo

    2014-10-13

    In the present study, enzyme assisted extraction of Fructus Mori polysaccharides (FMPS) from F. mori using four kinds of enzymes and three compound enzymes were examined. Research found that glucose oxidase offered a better performance in enhancement of the extraction yields of FMPS, antioxidant and activate alcohol dehydrogenase activities. The glucose oxidase assisted extraction process was further optimized by using response surface method (RSM) to obtain maximum yield of crude FMPS. The results showed that optimized extraction conditions were ratio of enzyme amount 0.40%, enzyme treated time 38 min, treated temperature 58 °C and liquid-solid radio 11.0. Under these conditions, the mean experimental value of extraction yield (16.16 ± 0.14%) corresponded well with the predicted values and increased 160% than none enzyme treated ones. Pharmacological verification tests showed that F. mori crude polysaccharides had good antioxidant and activate alcohol dehydrogenase activities in vitro.

  11. The 69 kDa Escherichia coli maltodextrin glucosidase does not get encapsulated underneath GroES and folds through trans mechanism during GroEL/GroES-assisted folding.

    PubMed

    Paul, Subhankar; Singh, Chanpreet; Mishra, Saroj; Chaudhuri, Tapan K

    2007-09-01

    Escherichia coli chaperonin GroEL and GroES assist in folding of a wide variety of substrate proteins in the molecular mass range of approximately 50 kDa, using cis mechanism, but limited information is available on how they assist in folding of larger proteins. Considering that the central cavity of GroEL can accommodate a non-native protein of approximately 60 kDa, it is important to study the GroEL-GroES-assisted folding of substrate proteins that are large enough for cis encapsulation. In this study, we have reported the mechanism of GroEL/GroES-assisted in vivo and in vitro folding of a 69 kDa monomeric E. coli protein maltodextrin glucosidase (MalZ). Coexpression of GroEL and GroES in E. coli causes a 2-fold enhancement of exogenous MalZ activity in vivo. In vitro, GroEL and GroES in the presence of ATP give rise to a 7-fold enhancement in MalZ refolding. Neither GroEL nor single ring GroEL (SR1) in the presence or absence of ATP could enhance the in vitro folding of MalZ. GroES could not encapsulate GroEL-bound MalZ. All these experimental findings suggested that GroEL/GroES-assisted folding of MalZ followed trans mechanism, whereas denatured MalZ and GroES bound to the opposite rings of a GroEL molecule.

  12. [The informative mechanisms of systemic organization of psychic activity].

    PubMed

    Sudakov, K V

    2012-01-01

    In this review on the basis of functional systems theory developed by P. Anokhin theoretical approaches to informative mechanisms of systemic organization of psychic activity are presented. Author formulates the conception on discrete system quantums of psychic and behavioral activity from needs to its satisfaction and develops its informative equivalents. It was shown that informative equivalents of needs and its satisfaction are reflected in structures of action acceptors in the form of dynamic informative images. On the basis of acceptors of results of action informative systemic quantums are developed which constantly control its manifestation in behavioral systemic quantums. Informative systemic quantums are extracted in advance by predominate motivations and are associated with negative emotions of needs and positive emotions of their satisfaction. The content of this review confirms I.P. Pavlov's foresight on possible confluence of material and idealistic processes in psychic human activity.

  13. Probable Mechanism(s) of Antifungal Activity of SJA-95, a Heptaene Polyene Antibiotic

    PubMed Central

    Desai, S. K.; Naik, S. R.

    2008-01-01

    A new strain, streptomyces sp. S. 24 was isolated from a soil sample collected from Japan. The strain produced heptaene polyene antibiotic, SJA-95, in submerged culture and found to elicit promising antifungal activity against yeasts, filamentous fungi and clinical isolates, both in vitro and in vivo. Experimental studies were carried out using biological methods to understand the probable mechanism(s) of antifungal activity of SJA-95. Our experimental findings suggest that SJA-95 binds more avidly to ergosterol, the sterol in fungal cell membranes, than to cholesterol found in mammalian cell membranes. Such preferential binding of SJA-95 to ergosterol might help to establish its usefulness as a chemotherapeutic agent with lesser adverse reactions. PMID:20046706

  14. Probable Mechanism(s) of Antifungal Activity of SJA-95, a Heptaene Polyene Antibiotic.

    PubMed

    Desai, S K; Naik, S R

    2008-01-01

    A new strain, streptomyces sp. S. 24 was isolated from a soil sample collected from Japan. The strain produced heptaene polyene antibiotic, SJA-95, in submerged culture and found to elicit promising antifungal activity against yeasts, filamentous fungi and clinical isolates, both in vitro and in vivo. Experimental studies were carried out using biological methods to understand the probable mechanism(s) of antifungal activity of SJA-95. Our experimental findings suggest that SJA-95 binds more avidly to ergosterol, the sterol in fungal cell membranes, than to cholesterol found in mammalian cell membranes. Such preferential binding of SJA-95 to ergosterol might help to establish its usefulness as a chemotherapeutic agent with lesser adverse reactions.

  15. TOPICAL REVIEW: Electric current activated/assisted sintering (ECAS): a review of patents 1906-2008

    NASA Astrophysics Data System (ADS)

    Grasso, Salvatore; Sakka, Yoshio; Maizza, Giovanni

    2009-10-01

    The electric current activated/assisted sintering (ECAS) is an ever growing class of versatile techniques for sintering particulate materials. Despite the tremendous advances over the last two decades in ECASed materials and products there is a lack of comprehensive reviews on ECAS apparatuses and methods. This paper fills the gap by tracing the progress of ECAS technology from 1906 to 2008 and surveys 642 ECAS patents published over more than a century. It is found that the ECAS technology was pioneered by Bloxam (1906 GB Patent No. 9020) who developed the first resistive sintering apparatus. The patents were searched by keywords or by cross-links and were withdrawn from the Japanese Patent Office (342 patents), the United States Patent and Trademark Office (175 patents), the Chinese State Intellectual Property Office of P.R.C. (69 patents) and the World Intellectual Property Organization (12 patents). A subset of 119 (out of 642) ECAS patents on methods and apparatuses was selected and described in detail with respect to their fundamental concepts, physical principles and importance in either present ECAS apparatuses or future ECAS technologies for enhancing efficiency, reliability, repeatability, controllability and productivity. The paper is divided into two parts, the first deals with the basic concepts, features and definitions of basic ECAS and the second analyzes the auxiliary devices/peripherals. The basic ECAS is classified with reference to discharge time (fast and ultrafast ECAS). The fundamental principles and definitions of ECAS are outlined in accordance with the scientific and patent literature.

  16. Role of MHD activity in LH-assisted discharges in the PBX-M tokamak

    SciTech Connect

    Talvard, M.; Bell, R.E.; Bernabei, S.; Kaye, S.; Okabayashi, M.; Sesnic, S.; von Goeler, S.

    1995-01-01

    A data base for the 1993 run period of PBX-M has been documented (i) to investigate whether it was possible to forecast the development of MHD instabilities often observed in LH assisted discharges and (ii) to detail the origin, the nature and the effects of those instabilities. The deposition radius of the RF current, the plasma internal inductance and the LH power are used to separate MHD active and quiescent regimes prior the MHD onset. 1/1, 2/1, 3/1 global modes driven by the m = 2, n = 1 component are observed in discharges with LHCD. The destabilization is attributed to an increase of the current density gradient within the q = 2 surface. MHD fluctuations reduce the soft x-ray and hard x-ray intensities mainly around the RF current deposition radius. Minor disruptions with large inversion radii and mode locking are analyzed. Pi possible precursor to the MHD is evidenced on the hard x-ray horizontal profiles. A resonance between fast trapped electrons and turbulent waves present in the background plasma is proposed to support the observations.

  17. Mediator-assisted simultaneous probing of cytosolic and mitochondrial redox activity in living cells.

    PubMed

    Heiskanen, Arto; Spégel, Christer; Kostesha, Natalie; Lindahl, Sofia; Ruzgas, Tautgirdas; Emnéus, Jenny

    2009-01-01

    This work describes an electron transfer mediator-assisted amperometric flow injection method for assessing redox enzyme activity in different subcellular compartments of the phosphoglucose isomerase deletion mutant strain of Saccharomyces cerevisiae, EBY44. The method is demonstrated using the ferricyanide-menadione double mediator system to study the effect of dicoumarol, an inhibitor of cytosolic and mitochondrial oxidoreductases and an uncoupler of the electron transport chain. Evaluation of the role of NAD(P)H-producing pathways in mediating biological effects is facilitated by introducing either fructose or glucose as the carbon source, yielding either NADH or NADPH through the glycolytic or pentose phosphate pathway, respectively. Respiratory noncompetent cells show greater inhibition of cytosolic menadione-reducing enzymes when NADH rather than NADPH is produced. Spectrophotometric in vitro assays show no difference between the cofactors. Respiratory competent cells show cytosolic inhibition only when NADPH is produced, whereas production of NADH reveals uncoupling at low dicoumarol concentrations and inhibition of complexes III and IV at higher concentrations. Spectrophotometric assays only indicate the presence of cytosolic inhibition regardless of the reduced cofactor used. This article shows the applicability of the amperometric method and emphasizes the significance of determining biological effects of chemicals in living cells.

  18. Ultrasound-assisted adsorption of 4-dodecylbenzene sulfonate from aqueous solutions by corn cob activated carbon.

    PubMed

    Milenković, D D; Bojić, A Lj; Veljković, V B

    2013-05-01

    This study was aimed at removal of 4-dodecylbenzene sulfonate (DBS) ions from aqueous solutions by ultrasound-assisted adsorption onto the carbonized corn cob (AC). The main attention was focused on modeling the equilibrium and kinetics of adsorption of DBS onto the AC. The AC was prepared from ground dried corn cob by carbonization and activation by carbon dioxide at 880°C for 2h in a rotary furnace. The adsorption isotherm data were fitted by the Langmuir model in both the absence and the presence of ultrasound (US). The maximum adsorption capacities of the adsorbent for DBS, calculated from the Langmuir isotherms, were 29.41mg/g and 27.78mg/g in the presence of US and its absence, respectively. The adsorption process in the absence and the presence of US obeyed the pseudo second-order kinetics. The intraparticular diffusion model indicated that the adsorption of DBS ions on the AC was diffusion controlled as well as that US promoted intraparticular diffusion. The ΔG° values, -24.03kJ/mol, -25.78kJ/mol and -27.78kJ/mol, were negative at all operating temperatures, verifying that the adsorption of DBS ions was spontaneous and thermodynamically favorable. The positive value of ΔS°=187J/molK indicated the increased randomness at the adsorbent-adsorbate interface during the adsorption of DBS ions by the AC. PMID:23187067

  19. Glycosylated antitumor ether lipids: activity and mechanism of action.

    PubMed

    Arthur, Gilbert; Bittman, Robert

    2014-05-01

    Glycosylated antitumor ether lipids (GAELs) are distinguished from the alkyllysophospholipids or alkylphosphocholines classes of antitumor ether lipids (AEL) by the presence of a sugar moiety. Non-phosphorus GAELs, the subject of this review, have a sugar moiety in place of the phosphobase found in alkyllysophospholipids. Analogues of non-phosphorus GAELs with glucose, maltose, arabinose, or disaccharide moieties have been synthesized. Non-phosphorus GAELs with monosaccharides have cytotoxic and antiproliferative effects against cancer cells derived from a wide range of tissues, including drug resistant cell lines. The most active compound of this group to date is 1-O-hexadecyl-2-O-methyl-3-O-(2'-amino-2'-deoxy-β-D-glucopyranosyl)-sn-glycerol (11), which displays in vitro activity similar to or greater than that of ET-18-OCH3, the AEL "gold" standard. While the detailed molecular mechanism of action of non-phosphorus GAELs is not known, the data indicate that non-phosphorus GAELs are taken up by endocytosis and incorporated into early endosomes. The presence of non-phosphorus GAELs perturbs the maturation of the endocytic vesicles, resulting in the formation of large acidic vacuoles. Cell death appears to be the result of the release of cathepsins from the vacuoles into the cytosol and subsequent activation of a death pathway that is independent of the mitochondria and independent of apoptosis. The ability of these GAELs to kill cells via an apoptosis-independent mechanism makes them prime candidates for development of effective compounds against chemo-resistant tumors and cancer stem cells. The disaccharide-linked GAELs do not have cytotoxic activity but rather inhibit cancer cell motility due to the ability of the compounds to block specific calcium-activated potassium channels in cells. The antitumor activities displayed by these experimental compounds augurs well for their eventual development into clinically useful agents for cancer treatment.

  20. Mechanism of phospho-ubiquitin-induced PARKIN activation.

    PubMed

    Wauer, Tobias; Simicek, Michal; Schubert, Alexander; Komander, David

    2015-08-20

    The E3 ubiquitin ligase PARKIN (encoded by PARK2) and the protein kinase PINK1 (encoded by PARK6) are mutated in autosomal-recessive juvenile Parkinsonism (AR-JP) and work together in the disposal of damaged mitochondria by mitophagy. PINK1 is stabilized on the outside of depolarized mitochondria and phosphorylates polyubiquitin as well as the PARKIN ubiquitin-like (Ubl) domain. These phosphorylation events lead to PARKIN recruitment to mitochondria, and activation by an unknown allosteric mechanism. Here we present the crystal structure of Pediculus humanus PARKIN in complex with Ser65-phosphorylated ubiquitin (phosphoUb), revealing the molecular basis for PARKIN recruitment and activation. The phosphoUb binding site on PARKIN comprises a conserved phosphate pocket and harbours residues mutated in patients with AR-JP. PhosphoUb binding leads to straightening of a helix in the RING1 domain, and the resulting conformational changes release the Ubl domain from the PARKIN core; this activates PARKIN. Moreover, phosphoUb-mediated Ubl release enhances Ubl phosphorylation by PINK1, leading to conformational changes within the Ubl domain and stabilization of an open, active conformation of PARKIN. We redefine the role of the Ubl domain not only as an inhibitory but also as an activating element that is restrained in inactive PARKIN and released by phosphoUb. Our work opens up new avenues to identify small-molecule PARKIN activators. PMID:26161729

  1. Mechanism of phospho-ubiquitin induced PARKIN activation

    PubMed Central

    Wauer, Tobias; Simicek, Michal; Schubert, Alexander; Komander, David

    2016-01-01

    Summary The E3 ubiquitin ligase PARKIN (encoded by PARK2) and the protein kinase PINK1 (encoded by PARK6) are mutated in autosomal recessive juvenile Parkinsonism (AR-JP) and work together in the disposal of damaged mitochondria by mitophagy1–3. PINK1 is stabilised on the outside of depolarised mitochondria, and phosphorylates poly-ubiquitin (polyUb)4–8 as well as the PARKIN Ub-like (Ubl) domain9,10. These phosphorylation events lead to PARKIN recruitment to mitochondria, and activation by an unknown allosteric mechanism4–12. Here we present the crystal structure of Pediculus humanus PARKIN in complex with Ser65-phosphorylated ubiquitin (phosphoUb), revealing the molecular basis for PARKIN recruitment and activation. The phosphoUb binding site on PARKIN comprises a conserved phosphate pocket and harbours residues mutated in AR-JP patients. PhosphoUb binding leads to straightening of a helix in the RING1 domain, and the resulting conformational changes release the Ubl domain from the PARKIN core; this activates PARKIN. Moreover, phosphoUb-mediated Ubl release enhances Ubl phosphorylation by PINK1, leading to conformational changes within the Ubl domain and stabilisation of an open, active conformation of PARKIN. We redefine the role of the Ubl domain not only as an inhibitory13 but also as an activating element that is restrained in inactive PARKIN and released by phosphoUb. Our work opens new avenues to identify small molecule PARKIN activators. PMID:26161729

  2. Mechanical properties characterization and modeling of active polymer gels

    NASA Astrophysics Data System (ADS)

    Marra, Steven Paul

    Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as actuators and "artificial muscles." While much work has been done to study the behavior and properties of these gels, little information is available regarding the full constitutive description of the mechanical and actuation properties. This work focuses on developing a means of characterizing the mechanical properties of active polymer gels and describing how these properties evolve as the gel actuates. Poly(vinyl alcohol)-poly(acrylic acid) (PVA-PAA) gel was chosen as the model material for this work because it is relatively simple and safe to both fabricate and actuate. PVA-PAA gels are fabricated on-site using a solvent-casting technique. These gels expand when moved from acidic to basic solutions, and contract when moved from basic to acidic solutions. Citric acid and sodium bicarbonate were used as the testing solutions for this work. The mechanical properties of the gel were characterized by conducting uniaxial and biaxial tests on thin PVA-PAA gel films. A biaxial testing system has been developed which can measure stresses and deformations of these films in a variety of liquid environments. The experimental results on PVA-PAA gels show these materials to be relatively compliant, and slightly viscoelastic and compressible. These gels are also capable of large recoverable deformations in both acidic and basic environments. A thermodynamically consistent finite-elastic constitutive model was developed to describe the mechanical and actuation behaviors of active polymer gels. The mechanical properties of the gel are characterized by a free-energy function, and the model utilizes an evolving internal variable to describe the actuation

  3. Effective dopant activation by susceptor-assisted microwave annealing of low energy boron implanted and phosphorus implanted silicon

    SciTech Connect

    Zhao, Zhao; Vemuri, Rajitha N. P.; Alford, T. L.; David Theodore, N.; Lu, Wei; Lau, S. S.; Lanz, A.

    2013-12-28

    Rapid processing and reduced end-of-range diffusion result from susceptor-assisted microwave (MW) annealing, making this technique an efficient processing alternative for electrically activating dopants within ion-implanted semiconductors. Sheet resistance and Hall measurements provide evidence of electrical activation. Susceptor-assisted MW annealing, of ion-implanted Si, enables more effective dopant activation and at lower temperatures than required for rapid thermal annealing (RTA). Raman spectroscopy and ion channeling analyses are used to monitor the extent of ion implantation damage and recrystallization. The presence and behavior of extended defects are monitored by cross-section transmission electron microscopy. Phosphorus implanted Si samples experience effective electrical activation upon MW annealing. On the other hand, when boron implanted Si is MW annealed, the growth of extended defects results in reduced crystalline quality that hinders the electrical activation process. Further comparison of dopant diffusion resulting from MW annealing and rapid thermal annealing is performed using secondary ion mass spectroscopy. MW annealed ion implanted samples show less end-of-range diffusion when compared to RTA samples. In particular, MW annealed P{sup +} implanted samples achieve no visible diffusion and equivalent electrical activation at a lower temperature and with a shorter time-duration of annealing compared to RTA. In this study, the peak temperature attained during annealing does not depend on the dopant species or dose, for susceptor-assisted MW annealing of ion-implanted Si.

  4. Effective dopant activation by susceptor-assisted microwave annealing of low energy boron implanted and phosphorus implanted silicon

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; David Theodore, N.; Vemuri, Rajitha N. P.; Lu, Wei; Lau, S. S.; Lanz, A.; Alford, T. L.

    2013-12-01

    Rapid processing and reduced end-of-range diffusion result from susceptor-assisted microwave (MW) annealing, making this technique an efficient processing alternative for electrically activating dopants within ion-implanted semiconductors. Sheet resistance and Hall measurements provide evidence of electrical activation. Susceptor-assisted MW annealing, of ion-implanted Si, enables more effective dopant activation and at lower temperatures than required for rapid thermal annealing (RTA). Raman spectroscopy and ion channeling analyses are used to monitor the extent of ion implantation damage and recrystallization. The presence and behavior of extended defects are monitored by cross-section transmission electron microscopy. Phosphorus implanted Si samples experience effective electrical activation upon MW annealing. On the other hand, when boron implanted Si is MW annealed, the growth of extended defects results in reduced crystalline quality that hinders the electrical activation process. Further comparison of dopant diffusion resulting from MW annealing and rapid thermal annealing is performed using secondary ion mass spectroscopy. MW annealed ion implanted samples show less end-of-range diffusion when compared to RTA samples. In particular, MW annealed P+ implanted samples achieve no visible diffusion and equivalent electrical activation at a lower temperature and with a shorter time-duration of annealing compared to RTA. In this study, the peak temperature attained during annealing does not depend on the dopant species or dose, for susceptor-assisted MW annealing of ion-implanted Si.

  5. Physiological mechanisms for the modulation of pannexin 1 channel activity

    PubMed Central

    Sandilos, Joanna K; Bayliss, Douglas A

    2012-01-01

    It is widely recognized that ATP, along with other nucleotides, subserves important intercellular signalling processes. Among various nucleotide release mechanisms, the relatively recently identified pannexin 1 (Panx1) channel is gaining prominence by virtue of its ability to support nucleotide permeation and release in a variety of different tissues. Here, we review recent advances in our understanding of the factors that control Panx1 channel activity. By using electrophysiological and biochemical approaches, diverse mechanisms that dynamically regulate Panx1 channel function have been identified in various settings; these include, among others, activation by caspase-mediated channel cleavage in apoptotic immune cells, by G protein-coupled receptors in vascular smooth muscle, by low oxygen tension in erythrocytes and neurons, by high extracellular K+ in various cell types and by stretch/strain in airway epithelia. Delineating the distinct mechanisms of Panx1 modulation that prevail in different physiological contexts provides the possibility that these channels, and ATP release, could ultimately be targeted in a context-dependent manner. PMID:23070703

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  7. Hair Growth Promotion Activity and Its Mechanism of Polygonum multiflorum

    PubMed Central

    Li, Yunfei; Han, Mingnuan; Lin, Pei; He, Yanran; Yu, Jie; Zhao, Ronghua

    2015-01-01

    Polygonum multiflorum Radix (PMR) has long history in hair growth promotion and hair coloring in clinical applications. However, several crucial problems in its clinic usage and mechanisms are still unsolved or lack scientific evidences. In this research, C57BL/6J mice were used to investigate hair growth promotion activity and possible mechanism of PMR and Polygonum multiflorum Radix Preparata (PMRP). Hair growth promotion activities were investigated by hair length, hair covered skin ratio, the number of follicles, and hair color. Regulation effects of several cytokines involved in the hair growth procedure were tested, such as fibroblast growth factor (FGF-7), Sonic Hedgehog (SHH), β-catenin, insulin-like growth factor-1 (IGF-1), and hepatocyte growth factor (HGF). Oral PMR groups had higher hair covered skin ratio (100 ± 0.00%) than oral PMRP groups (48%~88%). However, topical usage of PMRP had about 90% hair covered skin ratio. Both oral administration of PMR and topically given PMRP showed hair growth promotion activities. PMR was considered to be more suitable for oral administration, while PMRP showed greater effects in external use. The hair growth promotion effect of oral PMR was most probably mediated by the expression of FGF-7, while topical PMRP promoted hair growth by the stimulation of SHH expression. PMID:26294926

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

    PubMed

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

    2016-06-01

    The reaction mechanisms of mercury (Hg) adsorption and oxidation on halogenated activated carbon (AC) have been completely studied for the first time using density functional theory (DFT) method. Two different halogenated AC models, namely X-AC and X-AC-X (X=Cl, Br, I), were adopted. The results revealed that HgX is found to be stable-state on the AC edge since its further desorption from the AC as HgX, or further oxidation to HgX2, are energetically unfavorable. Remarkably, the halide type does not significantly affect the Hg adsorption energy but it strongly affects the activation energy barrier of HgX formation, which obviously increases in the order HgIBr-AC>Cl-AC. Thus, the study of the complete reaction mechanism is essential because the adsorption energy can not be used as a guideline for the rational material design in the halide impregnated AC systems. The activation energy is an important descriptor for the predictions of sorbent reactivity to the Hg oxidation process. PMID:26943019

  9. Modeling trapping mechanism for PCB adsorption on activated carbon

    NASA Astrophysics Data System (ADS)

    Jensen, Bjørnar; Kvamme, Bjørn; Kuznetsova, Tatyana; Oterhals, A.˚ge

    2012-12-01

    The levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran (PCDD/F) and dioxin-like polychlorinated biphenyl (DL-PCB) in fishmeal and fish oil produced for use in feed for salmon is above present European legislation levels in some regions of the world and different decontamination approaches have been proposed [1]. One of these is adsorption on activated carbon. This approach appears to be efficient for adsorption of PCDD/F but less efficient for DL-PCB [2]. Activated carbon consists of slit pores with average sizes of 20 - 50 Ångstroms. One hypothesis [2] for the mechanism of trapping DL-PCB is reduced ability for intramolecular movements of the PCB molecules inside the slit pores. In order to investigate this hypothesis we have used quantum mechanics [3] to characterize two DL-PCB congeners, respectively congener 77 (3,3',4,4'-Tetrachlorobiphenyl) and congener 118 (2,3',4,4',5-Pentachlorobiphenyl) and Triolein (18:1) [4] as a major constituent of the solvent fish oil. A model for activated carbon was constructed using a crystal structure of graphite from the American Mineralogist Crystal Structure Database [5]. The crystal structure used was originally from Wyckoff [6]. A small program had to be written to generate the desired graphite structure as it contains no less than 31232 Carbon atoms. Partial atomic charges were estimated using QM with DFT/B3LYP/6-311+g** and SM6 [7].

  10. On the molecular mechanisms of mitotic kinase activation.

    PubMed

    Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon

    2012-11-01

    During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein-protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients. PMID:23226601

  11. On the molecular mechanisms of mitotic kinase activation.

    PubMed

    Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon

    2012-11-01

    During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein-protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients.

  12. On the molecular mechanisms of mitotic kinase activation

    PubMed Central

    Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon

    2012-01-01

    During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein–protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients. PMID:23226601

  13. Reviews on Mechanisms of In Vitro Antioxidant Activity of Polysaccharides

    PubMed Central

    Wang, Junqiao; Hu, Shuzhen; Nie, Shaoping; Yu, Qiang; Xie, Mingyong

    2016-01-01

    It is widely acknowledged that the excessive reactive oxygen species (ROS) or reactive nitrogen species (RNS) induced oxidative stress will cause significant damage to cell structure and biomolecular function, directly or indirectly leading to a number of diseases. The overproduction of ROS/RNS will be balanced by nonenzymatic antioxidants and antioxidant enzymes. Polysaccharide or glycoconjugates derived from natural products are of considerable interest from the viewpoint of potent in vivo and in vitro antioxidant activities recently. Particularly, with regard to the in vitro antioxidant systems, polysaccharides are considered as effective free radical scavenger, reducing agent, and ferrous chelator in most of the reports. However, the underlying mechanisms of these antioxidant actions have not been illustrated systematically and sometimes controversial results appeared among various literatures. To address this issue, we summarized the latest discoveries and advancements in the study of antioxidative polysaccharides and gave a detailed description of the possible mechanisms. PMID:26682009

  14. Whisker encoding of mechanical events during active tactile exploration

    PubMed Central

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

    2012-01-01

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

  15. Synaptic mechanisms underlying sparse coding of active touch.

    PubMed

    Crochet, Sylvain; Poulet, James F A; Kremer, Yves; Petersen, Carl C H

    2011-03-24

    Sensory information is actively gathered by animals, but the synaptic mechanisms driving neuronal circuit function during active sensory processing are poorly understood. Here, we investigated the synaptically driven membrane potential dynamics during active whisker sensation using whole-cell recordings from layer 2/3 pyramidal neurons in the primary somatosensory barrel cortex of behaving mice. Although whisker contact with an object evoked rapid depolarization in all neurons, these touch responses only drove action potentials in ∼10% of the cells. Such sparse coding was ensured by cell-specific reversal potentials of the touch-evoked response that were hyperpolarized relative to action potential threshold for most neurons. Intercontact interval profoundly influenced touch-evoked postsynaptic potentials, interestingly without affecting the peak membrane potential of the touch response. Dual whole-cell recordings indicated highly correlated membrane potential dynamics during active touch. Sparse action potential firing within synchronized cortical layer 2/3 microcircuits therefore appears to robustly signal each active touch response.

  16. The growth hormone receptor: mechanism of activation and clinical implications.

    PubMed

    Brooks, Andrew J; Waters, Michael J

    2010-09-01

    Growth hormone is widely used clinically to promote growth and anabolism and for other purposes. Its actions are mediated via the growth hormone receptor, both directly by tyrosine kinase activation and indirectly by induction of insulin-like growth factor 1 (IGF-1). Insensitivity to growth hormone (Laron syndrome) can result from mutations in the growth hormone receptor and can be treated with IGF-1. This treatment is, however, not fully effective owing to the loss of the direct actions of growth hormone and altered availability of exogenous IGF-1. Excessive activation of the growth hormone receptor by circulating growth hormone results in gigantism and acromegaly, whereas cell transformation and cancer can occur in response to autocrine activation of the receptor. Advances in understanding the mechanism of receptor activation have led to a model in which the growth hormone receptor exists as a constitutive dimer. Binding of the hormone realigns the subunits by rotation and closer apposition, resulting in juxtaposition of the catalytic domains of the associated tyrosine-protein kinase JAK2 below the cell membrane. This change results in activation of JAK2 by transphosphorylation, then phosphorylation of receptor tyrosines in the cytoplasmic domain, which enables binding of adaptor proteins, as well as direct phosphorylation of target proteins. This model is discussed in the light of salient information from closely related class 1 cytokine receptors, such as the erythropoietin, prolactin and thrombopoietin receptors. PMID:20664532

  17. Brain mechanical property measurement using MRE with intrinsic activation

    NASA Astrophysics Data System (ADS)

    Weaver, John B.; Pattison, Adam J.; McGarry, Matthew D.; Perreard, Irina M.; Swienckowski, Jessica G.; Eskey, Clifford J.; Lollis, S. Scott; Paulsen, Keith D.

    2012-11-01

    , termed intrinsic activation, produces sufficient motion to allow mechanical properties to be recovered. The poroelastic model is more consistent with the measured data from brain at low frequencies than the linear elastic model. Intrinsic activation allows MRE to be performed without a device shaking the head so the patient notices no differences between it and the other sequences in an MR examination.

  18. Physical mechanisms of solar activity effects in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Ebel, A.

    1989-01-01

    A great variety of physical mechanisms of possibly solar induced variations in the middle atmosphere has been discussed in the literature during the last decades. The views which have been put forward are often controversial in their physical consequences. The reason may be the complexity and non-linearity of the atmospheric response to comparatively weak forcing resulting from solar activity. Therefore this review focuses on aspects which seem to indicate nonlinear processes in the development of solar induced variations. Results from observations and numerical simulations are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  20. 78 FR 52519 - Agency Information Collection Activities; Comment Request; Student Assistance General Provisions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-23

    ... K--Cash Management AGENCY: Federal Student Aid (FSA), Department of Education (ED). ACTION: Notice...: Student Assistance General Provisions--Subpart K--Cash Management. OMB Control Number: 1845-0049. Type...

  1. Molecular mechanism underlying Akt activation in zinc-induced cardioprotection

    PubMed Central

    Lee, SungRyul; Chanoit, Guillaume; McIntosh, Rachel; Zvara, David A.; Xu, Zhelong

    2009-01-01

    Our previous study demonstrated that zinc prevents cardiac reperfusion injury by targeting the mitochondrial permeability transition pore (mPTP) via Akt and glycogen synthetase kinase 3β (GSK-3β). We aimed to address the mechanism by which zinc activates Akt. Treatment of H9c2 cells with ZnCl2 (10 μM) in the presence of the zinc ionophore pyrithione (4 μM) for 20 min enhanced Akt phosphorylation (Ser473), indicating that zinc can rapidly activate Akt. Zinc did not alter either phosphatase and tensin homolog deleted on chromosome 10 (PTEN) phosphorylation and total PTEN protein levels or PTEN oxidation, implying that PTEN may not play a role in the action of zinc. However, zinc-induced Akt phosphorylation was blocked by both the nonselective receptor tyrosine kinase (RTK) inhibitor genistein and the selective insulin-like growth factor-1 RTK (IGF-1RTK) inhibitor AG1024, indicating that zinc activates Akt via IGF-1RTK. Zinc-induced phosphorylation of protein tyrosine and Ser/Thr was also abolished by AG1024. In addition, zinc markedly enhanced phosphorylation of IGF-1 receptor (IGF-1R), which was again reversed by genistein and AG1024. A confocal imaging study revealed that AG1024 abolished the preventive effect of zinc on oxidant-induced mPTP opening, confirming that IGF-1RTK plays a role in zinc-induced cardioprotection. Furthermore, zinc decreased the activity of protein phosphatase 2A (PP2A), a major protein Ser/Thr phosphatase, implying that protein Ser/Thr phosphatases may also play a role in the action of zinc on Akt activity. Taken together, these findings demonstrate that exogenous zinc activates Akt via IGF-1RTK and prevents the mPTP opening in cardiac cells. Inactivation of Ser/Thr protein phosphatases may also contribute to zinc-induced Akt activation. PMID:19525380

  2. Synthesis of nanoparticles from malleable and ductile metals using powder-free, reactant-assisted mechanical attrition.

    PubMed

    McMahon, Brandon W; Perez, Jesus Paulo L; Yu, Jiang; Boatz, Jerry A; Anderson, Scott L

    2014-11-26

    A reactant-assisted mechanochemical method was used to produce copious nanoparticles from malleable/ductile metals, demonstrated here for aluminum, iron, and copper. The milling media is intentionally degraded via a reactant-accelerated wear process, where the reactant aids particle production by binding to the metal surfaces, enhancing particle production, and reducing the tendency toward mechanochemical (cold) welding. The mechanism is explored by comparing the effects of different types of solvents and solvent mixtures on the amount and type of particles produced. Particles were functionalized with oleic acid to aid in particle size separation, enhance dispersion in hydrocarbon solvents, and protect the particles from oxidation. For aluminum and iron, the result is air-stable particles, but for copper, the suspended particles are found to dissolve when exposed to air. Characterization was performed using electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance, and X-ray photoelectron spectroscopy. Density functional theory was used to examine the nature of carboxylic acid binding to the aluminum surface, confirming the dominance of bridging bidentate binding. PMID:25343708

  3. Tailored Height Gradients in Vertical Nanowire Arrays via Mechanical and Electronic Modulation of Metal-Assisted Chemical Etching.

    PubMed

    Otte, M A; Solis-Tinoco, V; Prieto, P; Borrisé, X; Lechuga, L M; González, M U; Sepulveda, B

    2015-09-01

    In current top-down nanofabrication methodologies the design freedom is generally constrained to the two lateral dimensions, and is only limited by the resolution of the employed nanolithographic technique. However, nanostructure height, which relies on certain mask-dependent material deposition or etching techniques, is usually uniform, and on-chip variation of this parameter is difficult and generally limited to very simple patterns. Herein, a novel nanofabrication methodology is presented, which enables the generation of high aspect-ratio nanostructure arrays with height gradients in arbitrary directions by a single and fast etching process. Based on metal-assisted chemical etching using a catalytic gold layer perforated with nanoholes, it is demonstrated how nanostructure arrays with directional height gradients can be accurately tailored by: (i) the control of the mass transport through the nanohole array, (ii) the mechanical properties of the perforated metal layer, and (iii) the conductive coupling to the surrounding gold film to accelerate the local electrochemical etching process. The proposed technique, enabling 20-fold on-chip variation of nanostructure height in a spatial range of a few micrometers, offers a new tool for the creation of novel types of nano-assemblies and metamaterials with interesting technological applications in fields such as nanophotonics, nanophononics, microfluidics or biomechanics. PMID:26033973

  4. Tailored Height Gradients in Vertical Nanowire Arrays via Mechanical and Electronic Modulation of Metal-Assisted Chemical Etching.

    PubMed

    Otte, M A; Solis-Tinoco, V; Prieto, P; Borrisé, X; Lechuga, L M; González, M U; Sepulveda, B

    2015-09-01

    In current top-down nanofabrication methodologies the design freedom is generally constrained to the two lateral dimensions, and is only limited by the resolution of the employed nanolithographic technique. However, nanostructure height, which relies on certain mask-dependent material deposition or etching techniques, is usually uniform, and on-chip variation of this parameter is difficult and generally limited to very simple patterns. Herein, a novel nanofabrication methodology is presented, which enables the generation of high aspect-ratio nanostructure arrays with height gradients in arbitrary directions by a single and fast etching process. Based on metal-assisted chemical etching using a catalytic gold layer perforated with nanoholes, it is demonstrated how nanostructure arrays with directional height gradients can be accurately tailored by: (i) the control of the mass transport through the nanohole array, (ii) the mechanical properties of the perforated metal layer, and (iii) the conductive coupling to the surrounding gold film to accelerate the local electrochemical etching process. The proposed technique, enabling 20-fold on-chip variation of nanostructure height in a spatial range of a few micrometers, offers a new tool for the creation of novel types of nano-assemblies and metamaterials with interesting technological applications in fields such as nanophotonics, nanophononics, microfluidics or biomechanics.

  5. Intrinsic mechanisms of pain inhibition: activation by stress.

    PubMed

    Terman, G W; Shavit, Y; Lewis, J W; Cannon, J T; Liebeskind, J C

    1984-12-14

    Portions of the brain stem seem normally to inhibit pain. In man and laboratory animals these brain areas and pathways from them to spinal sensory circuits can be activated by focal stimulation. Endogenous opioids appear to be implicated although separate nonopioid mechanisms are also evident. Stress seems to be a natural stimulus triggering pain suppression. Properties of electric footshock have been shown to determine the opioid or nonopioid basis of stress-induced analgesia. Two different opioid systems can be activated by different footshock paradigms. This dissection of stress analgesia has begun to integrate divergent findings concerning pain inhibition and also to account for some of the variance that has obscured the reliable measurement of the effects of stress on tumor growth and immune function.

  6. Thermal and Optical Activation Mechanisms of Nanospring-Based Chemiresistors

    PubMed Central

    Dobrokhotov, Vladimir; Oakes, Landon; Sowell, Dewayne; Larin, Alexander; Hall, Jessica; Barzilov, Alexander; Kengne, Alex; Bakharev, Pavel; Corti, Giancarlo; Cantrell, Timothy; Prakash, Tej; Williams, Joseph; Bergman, Leah; Huso, Jesse; McIlroy, David

    2012-01-01

    Chemiresistors (conductometric sensor) were fabricated on the basis of novel nanomaterials—silica nanosprings ALD coated with ZnO. The effects of high temperature and UV illumination on the electronic and gas sensing properties of chemiresistors are reported. For the thermally activated chemiresistors, a discrimination mechanism was developed and an integrated sensor-array for simultaneous real-time resistance scans was built. The integrated sensor response was tested using linear discriminant analysis (LDA). The distinguished electronic signatures of various chemical vapors were obtained at ppm level. It was found that the recovery rate at high temperature drastically increases upon UV illumination. The feasibility study of the activation method by UV illumination at room temperature was conducted. PMID:22778604

  7. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    PubMed

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2014-11-01

    A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

  8. Ultrasonically assisted hydrothermal synthesis of activated carbon-HKUST-1-MOF hybrid for efficient simultaneous ultrasound-assisted removal of ternary organic dyes and antibacterial investigation: Taguchi optimization.

    PubMed

    Azad, F Nasiri; Ghaedi, M; Dashtian, K; Hajati, S; Pezeshkpour, V

    2016-07-01

    Activated carbon (AC) composite with HKUST-1 metal organic framework (AC-HKUST-1 MOF) was prepared by ultrasonically assisted hydrothermal method and characterized by FTIR, SEM and XRD analysis and laterally was applied for the simultaneous ultrasound-assisted removal of crystal violet (CV), disulfine blue (DSB) and quinoline yellow (QY) dyes in their ternary solution. In addition, this material, was screened in vitro for their antibacterial actively against Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO1) bacteria. In dyes removal process, the effects of important variables such as initial concentration of dyes, adsorbent mass, pH and sonication time on adsorption process optimized by Taguchi approach. Optimum values of 4, 0.02 g, 4 min, 10 mg L(-1) were obtained for pH, AC-HKUST-1 MOF mass, sonication time and the concentration of each dye, respectively. At the optimized condition, the removal percentages of CV, DSB and QY were found to be 99.76%, 91.10%, and 90.75%, respectively, with desirability of 0.989. Kinetics of adsorption processes follow pseudo-second-order model. The Langmuir model as best method with high applicability for representation of experimental data, while maximum mono layer adsorption capacity for CV, DSB and QY on AC-HKUST-1 estimated to be 133.33, 129.87 and 65.37 mg g(-1) which significantly were higher than HKUST-1 as sole material with Qm to equate 59.45, 57.14 and 38.80 mg g(-1), respectively.

  9. The Molecular Mechanism of Eukaryotic Elongation Factor 2 Kinase Activation*

    PubMed Central

    Tavares, Clint D. J.; Ferguson, Scarlett B.; Giles, David H.; Wang, Qiantao; Wellmann, Rebecca M.; O'Brien, John P.; Warthaka, Mangalika; Brodbelt, Jennifer S.; Ren, Pengyu; Dalby, Kevin N.

    2014-01-01

    Calmodulin (CaM)-dependent eukaryotic elongation factor 2 kinase (eEF-2K) impedes protein synthesis through phosphorylation of eukaryotic elongation factor 2 (eEF-2). It is subject to complex regulation by multiple upstream signaling pathways, through poorly described mechanisms. Precise integration of these signals is critical for eEF-2K to appropriately regulate protein translation rates. Here, an allosteric mechanism comprising two sequential conformations is described for eEF-2K activation. First, Ca2+/CaM binds eEF-2K with high affinity (Kd(CaM)app = 24 ± 5 nm) to enhance its ability to autophosphorylate Thr-348 in the regulatory loop (R-loop) by > 104-fold (kauto = 2.6 ± 0.3 s−1). Subsequent binding of phospho-Thr-348 to a conserved basic pocket in the kinase domain potentially drives a conformational transition of the R-loop, which is essential for efficient substrate phosphorylation. Ca2+/CaM binding activates autophosphorylated eEF-2K by allosterically enhancing kcatapp for peptide substrate phosphorylation by 103-fold. Thr-348 autophosphorylation results in a 25-fold increase in the specificity constant (kcatapp/Km(Pep-S)app), with equal contributions from kcatapp and Km(Pep-S)app, suggesting that peptide substrate binding is partly impeded in the unphosphorylated enzyme. In cells, Thr-348 autophosphorylation appears to control the catalytic output of active eEF-2K, contributing more than 5-fold to its ability to promote eEF-2 phosphorylation. Fundamentally, eEF-2K activation appears to be analogous to an amplifier, where output volume may be controlled by either toggling the power switch (switching on the kinase) or altering the volume control (modulating stability of the active R-loop conformation). Because upstream signaling events have the potential to modulate either allosteric step, this mechanism allows for exquisite control of eEF-2K output. PMID:25012662

  10. Mechanisms of control of alae nasi muscle activity.

    PubMed

    Mezzanotte, W S; Tangel, D J; White, D P

    1992-03-01

    Human upper airway dilator muscles are clearly influenced by chemical stimuli such as hypoxia and hypercapnia. Whether in humans there are upper airway receptors capable of modifying the activity of such muscles is unclear. We studied alae nasi electromyography (EMG) in normal men in an attempt to determine 1) whether increasing negative intraluminal pressure influences the activity of the alae nasi muscle, 2) whether nasal airway feedback mechanisms modify the activity of this muscle, and 3) if so, whether these receptor mechanisms are responding to mucosal temperature/pressure changes or to airway deformation. Alae nasi EMG was recorded in 10 normal men under the following conditions: 1) nasal breathing (all potential nasal receptors exposed), 2) oral breathing (nasal receptors not exposed), 3) nasal breathing with splints (airway deformation prevented), and 4) nasal breathing after nasal anesthesia (mucosal receptors anesthetized). In addition, in a separate group, the combined effects of anesthesia and nasal splints were assessed. Under each condition, EMG activity was monitored during basal breathing, progressive hypercapnia, and inspiratory resistive loading. Under all four conditions, both load and hypercapnia produced a significant increase in alae nasi EMG, with hypercapnia producing a similar increment in EMG regardless of nasal receptor exposure. On the other hand, loading produced greater increments in EMG during nasal than during oral breathing, with combined anesthesia plus splinting producing a load response similar to that observed during oral respiration. These observations suggest that nasal airway receptors have little effect on the alae nasi response to hypercapnia but appear to mediate the alae nasi response to loading or negative airway pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Machine Learning Assisted Design of Highly Active Peptides for Drug Discovery

    PubMed Central

    Giguère, Sébastien; Laviolette, François; Marchand, Mario; Tremblay, Denise; Moineau, Sylvain; Liang, Xinxia; Biron, Éric; Corbeil, Jacques

    2015-01-01

    The discovery of peptides possessing high biological activity is very challenging due to the enormous diversity for which only a minority have the desired properties. To lower cost and reduce the time to obtain promising peptides, machine learning approaches can greatly assist in the process and even partly replace expensive laboratory experiments by learning a predictor with existing data or with a smaller amount of data generation. Unfortunately, once the model is learned, selecting peptides having the greatest predicted bioactivity often requires a prohibitive amount of computational time. For this combinatorial problem, heuristics and stochastic optimization methods are not guaranteed to find adequate solutions. We focused on recent advances in kernel methods and machine learning to learn a predictive model with proven success. For this type of model, we propose an efficient algorithm based on graph theory, that is guaranteed to find the peptides for which the model predicts maximal bioactivity. We also present a second algorithm capable of sorting the peptides of maximal bioactivity. Extensive analyses demonstrate how these algorithms can be part of an iterative combinatorial chemistry procedure to speed up the discovery and the validation of peptide leads. Moreover, the proposed approach does not require the use of known ligands for the target protein since it can leverage recent multi-target machine learning predictors where ligands for similar targets can serve as initial training data. Finally, we validated the proposed approach in vitro with the discovery of new cationic antimicrobial peptides. Source code freely available at http://graal.ift.ulaval.ca/peptide-design/. PMID:25849257

  12. Machine learning assisted design of highly active peptides for drug discovery.

    PubMed

    Giguère, Sébastien; Laviolette, François; Marchand, Mario; Tremblay, Denise; Moineau, Sylvain; Liang, Xinxia; Biron, Éric; Corbeil, Jacques

    2015-04-01

    The discovery of peptides possessing high biological activity is very challenging due to the enormous diversity for which only a minority have the desired properties. To lower cost and reduce the time to obtain promising peptides, machine learning approaches can greatly assist in the process and even partly replace expensive laboratory experiments by learning a predictor with existing data or with a smaller amount of data generation. Unfortunately, once the model is learned, selecting peptides having the greatest predicted bioactivity often requires a prohibitive amount of computational time. For this combinatorial problem, heuristics and stochastic optimization methods are not guaranteed to find adequate solutions. We focused on recent advances in kernel methods and machine learning to learn a predictive model with proven success. For this type of model, we propose an efficient algorithm based on graph theory, that is guaranteed to find the peptides for which the model predicts maximal bioactivity. We also present a second algorithm capable of sorting the peptides of maximal bioactivity. Extensive analyses demonstrate how these algorithms can be part of an iterative combinatorial chemistry procedure to speed up the discovery and the validation of peptide leads. Moreover, the proposed approach does not require the use of known ligands for the target protein since it can leverage recent multi-target machine learning predictors where ligands for similar targets can serve as initial training data. Finally, we validated the proposed approach in vitro with the discovery of new cationic antimicrobial peptides. Source code freely available at http://graal.ift.ulaval.ca/peptide-design/.

  13. Deciphering molecular mechanism underlying hypolipidemic activity of echinocystic Acid.

    PubMed

    Han, Li; Lai, Peng; Du, Jun-Rong

    2014-01-01

    Our previous study showed that a triterpene mixture, consisting of echinocystic acid (EA) and oleanolic acid (OA) at a ratio of 4 : 1, dose-dependently ameliorated the hyperlipidemia and atherosclerosis in rabbits fed with high fat/high cholesterol diets. This study was aimed at exploring the mechanisms underlying antihyperlipidemic effect of EA. Molecular docking simulation of EA was performed using Molegro Virtual Docker (version: 4.3.0) to investigate the potential targets related to lipid metabolism. Based on the molecular docking information, isotope labeling method or spectrophotometry was applied to examine the effect of EA on the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, acyl-CoA:cholesterol acyltransferase (ACAT), and diacylglycerol acyltransferase (DGAT) in rat liver microsomes. Our results revealed a strong affinity of EA towards ACAT and DGAT in molecular docking analysis, while low binding affinity existed between EA and HMG-CoA reductase as well as between EA and cholesteryl ester transfer protein. Consistent with the results of molecular docking, in vitro enzyme activity assays showed that EA inhibited ACAT and DGAT, with IC50 values of 103 and 139  μ M, respectively, and exhibited no significant effect on HMG-CoA reductase activity. The present findings suggest that EA may exert hypolipidemic effect by inhibiting the activity of ACAT and DGAT. PMID:24669228

  14. Single-Molecule Manipulation Studies of a Mechanically Activated Protein

    NASA Astrophysics Data System (ADS)

    Botello, Eric; Harris, Nolan; Choi, Huiwan; Bergeron, Angela; Dong, Jing-Fei; Kiang, Ching-Hwa

    2009-10-01

    Plasma von Willebrand factor (pVWF) is the largest multimeric adhesion ligand found in human blood and must be adhesively activated by exposure to shear stress, like at sites of vascular injury, to initiate blood clotting. Sheared pVWF (sVWF) will undergo a conformational change from a loose tangled coil to elongated strings forming adhesive fibers by binding with other sVWF. VWF's adhesion activity is also related to its length, with the ultra-large form of VWF (ULVWF) being hyper-actively adhesive without exposure to shear stress; it has also been shown to spontaneously form fibers. We used single molecule manipulation techniques with the AFM to stretch pVWF, sVWF and ULVWF and monitor the forces as a function of molecular extension. We showed a similar increase in resistance to unfolding for sVWF and ULVWF when compared to pVWF. This mechanical resistance to forced unfolding is reduced when other molecules known to disrupt their fibril formation are present. Our results show that sVWF and ULVWF domains unfold at higher forces than pVWF, which is consistent with the hypothesis that shear stress induces lateral association that alters adhesion activity of pVWF.

  15. Molecular Mechanisms of Inflammasome Activation during Microbial Infections

    PubMed Central

    Broz, Petr; Monack, Denise M.

    2011-01-01

    Summary The innate immune system plays a crucial role in the rapid recognition and elimination of invading microbes. Detection of microbes relies on germ-line encoded pattern recognition receptors (PRRs) that recognize essential bacterial molecules, so-called pathogen-associated molecular patterns (PAMPs). A subset of PRRs, belonging to the NOD-like receptor (NLR) and the PYHIN protein families, detects viral and bacterial pathogens in the cytosol of host cells and induces the assembly of a multi-protein signaling platform called the inflammasome. The inflammasome serves as an activation platform for the mammalian cysteine protease caspase-1, a central mediator of innate immunity. Active caspase-1 promotes the maturation and release of interleukin-1β (IL-1β) and IL-18 as well as protein involved in cytoprotection and tissue repair. In addition, caspase-1 initiates a novel form of cell death called pyroptosis. Here we discuss latest advances and our insights on inflammasome stimulation by two model intracellular pathogens, Francisella tularensis and Salmonella typhimurium. Recent studies on these pathogens have significantly shaped our understanding of the molecular mechanisms of inflammasome activation and how microbes can evade or manipulate inflammasome activity. In addition, we review the role of the inflammasome adapter ASC in the caspase-1 autoproteolysis and new insights into the structure of the inflammasome complex. PMID:21884176

  16. Soft active matter: a contemporary example of Edwardsian statistical mechanics

    NASA Astrophysics Data System (ADS)

    Liverpool, Tanniemola

    Colonies of swimming bacteria, algae or spermatozoa are examples of active systems composed of interacting units that consume energy and collectively generate motion and mechanical stresses. Due to the anisotropy of their interactions, these active particles can exhibit orientational order at high concentrations and have been called ``living liquid crystals''. Biology at the cellular and multicellular scale provides numerous examples of these active systems. They provide a novel class of experimentally accessible system far from equilibrium. Their rich collective behaviour includes non-equilibrium phase transitions and pattern formation on mesoscopic scales. Interestingly however, some of the theoretical insights gained from field theories applied to equilibrium soft matter systems can be used to explain aspects of their behaviour, but with a number of surprising new twists. I will describe and summarise recent theoretical results characterising the behaviour of such soft active systems highlighting in particular the effects of their internal dynamics on their macroscopic behaviour. With support of the EPSRC Grant No. EP/G026440/1.

  17. Mechanisms of insulin action on sympathetic nerve activity

    NASA Technical Reports Server (NTRS)

    Muntzel, Martin S.; Anderson, Erling A.; Johnson, Alan Kim; Mark, Allyn L.

    1996-01-01

    Insulin resistance and hyperinsulinemia may contribute to the development of arterial hypertension. Although insulin may elevate arterial pressure, in part, through activation of the sympathetic nervous system, the sites and mechanisms of insulin-induced sympathetic excitation remain uncertain. While sympathoexcitation during insulin may be mediated by the baroreflex, or by modulation of norepinephrine release from sympathetic nerve endings, it has been shown repeatedly that insulin increases sympathetic outflow by actions on the central nervous system. Previous studies employing norepinephrine turnover have suggested that insulin causes sympathoexcitation by acting in the hypothalamus. Recent experiments from our laboratory involving direct measurements of regional sympathetic nerve activity have provided further evidence that insulin acts in the central nervous system. For example, administration of insulin into the third cerebralventricle increased lumbar but not renal or adrenal sympathetic nerve activity in normotensive rats. Interestingly, this pattern of regional sympathetic nerve responses to central neural administration of insulin is similar to that seen with systemic administration of insulin. Further, lesions of the anteroventral third ventricle hypothalamic (AV3V) region abolished increases in sympathetic activity to systemic administration of insulin with euglycemic clamp, suggesting that AV3V-related structures are critical for insulin-induced elevations in sympathetic outflow.

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

    PubMed Central

    Diedrichsen, Jörn

    2016-01-01

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

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

    PubMed

    Kriegeskorte, Nikolaus; Diedrichsen, Jörn

    2016-10-01

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

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

    PubMed

    Kriegeskorte, Nikolaus; Diedrichsen, Jörn

    2016-10-01

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

  1. Mechanisms for microvascular damage induced by ultrasound-activated microbubbles

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Brayman, Andrew A.; Evan, Andrew P.; Matula, Thomas J.

    2012-10-01

    To provide insight into the mechanisms of microvascular damage induced by ultrasound-activated microbubbles, experimental studies were performed to correlate microvascular damage to the dynamics of bubble-vessel interactions. High-speed photomicrography was used to record single microbubbles interacting with microvessels in ex vivo tissue, under the exposure of short ultrasound pulses with a center frequency of 1 MHz and peak negative pressures (PNP) ranging from 0.8-4 MPa. Vascular damage associated with observed bubble-vessel interactions was either indicated directly by microbubble extravasation or examined by transmission electron microscopy (TEM) analyses. As observed previously, the high-speed images revealed that ultrasound-activated microbubbles could cause distention and invagination of adjacent vessel walls, and could form liquid jets in microvessels. Vessel distention, invagination, and liquid jets were associated with the damage of microvessels whose diameters were smaller than those of maximally expanded microbubbles. However, vessel invagination appeared to be the dominant mechanism for the damage of relative large microvessels.

  2. Mechanisms for microvascular damage induced by ultrasound-activated microbubbles

    SciTech Connect

    Chen Hong; Brayman, Andrew A.; Evan, Andrew P.; Matula, Thomas J.

    2012-10-03

    To provide insight into the mechanisms of microvascular damage induced by ultrasound-activated microbubbles, experimental studies were performed to correlate microvascular damage to the dynamics of bubble-vessel interactions. High-speed photomicrography was used to record single microbubbles interacting with microvessels in ex vivo tissue, under the exposure of short ultrasound pulses with a center frequency of 1 MHz and peak negative pressures (PNP) ranging from 0.8-4 MPa. Vascular damage associated with observed bubble-vessel interactions was either indicated directly by microbubble extravasation or examined by transmission electron microscopy (TEM) analyses. As observed previously, the high-speed images revealed that ultrasound-activated microbubbles could cause distention and invagination of adjacent vessel walls, and could form liquid jets in microvessels. Vessel distention, invagination, and liquid jets were associated with the damage of microvessels whose diameters were smaller than those of maximally expanded microbubbles. However, vessel invagination appeared to be the dominant mechanism for the damage of relative large microvessels.

  3. Preparation of plutonium-bearing ceramics via mechanically activated precursor

    NASA Astrophysics Data System (ADS)

    Chizhevskaya, S. V.; Stefanovsky, S. V.

    2000-07-01

    The problem of excess weapons plutonium disposition is suggested to be solved by means of its incorporation in stable ceramics with high chemical durability and radiation resistivity. The most promising host phases for plutonium as well as uranium and neutron poisons (gadolinium, hafnium) are zirconolite, pyrochlore, zircon, zirconia [1,2], and murataite [3]. Their production requires high temperatures and a fine-grained homogeneous precursor to reach final waste form with high quality and low leachability. Currently various routes to homogeneous products preparation such as sol-gel technology, wet-milling, and grinding in a ball or planetary mill are used. The best result demonstrates sol-gel technology but this route is very complicated. An alternative technology for preparation of ceramic precursors is the treatment of the oxide batch with high mechanical energy [4]. Such a treatment produces combination of mechanical (fine milling with formation of various defects, homogenization) and chemical (split bonds with formation of active centers—free radicals, ion-radicals, etc.) effects resulting in higher reactivity of the activated batch.

  4. Ghost peaks observed after AP-MALDI experiment may disclose new ionization mechanism of matrix assisted hypersonic velocity impact ionization

    PubMed Central

    Moskovets, Eugene

    2015-01-01

    RATIONALE Understanding the mechanisms of MALDI promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample has been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laserless matrix-assisted ionization. METHODS An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser was turned off and MALDI sample was removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly- and doubly-charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. RESULTS The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. CONCLUSIONS The observations were partially consistent with a model of

  5. Microwave-assisted Synthesis and antifungal activity of coumarin[8,7-e][1,3]oxazine derivatives.

    PubMed

    Zhang, Ming-Zhi; Zhang, Rong-Rong; Yin, Wen-Zheng; Yu, Xiang; Zhang, Ya-Ling; Liu, Pin; Gu, Yu-Cheng; Zhang, Wei-Hua

    2016-08-01

    The synthesis of novel coumarin[8,7-e][1,3]oxazine derivatives through a microwave-assisted three-component one-pot Mannich reaction is described in this study. All the target compounds were evaluated in vitro for their antifungal activity against Botrytis cinerea, Colletotrichum capsici, Alternaria solani, Gibberella zeae, Rhizoctonia solani, and Alternaria mali. The preliminary bioassays showed that 5e, 5m, and 5s exhibited good antifungal activity and the most active compound was 5m with an [Formula: see text] value as low as 2.1 nM against Botrytis cinerea. PMID:26880591

  6. Teaching assistants' performance at identifying common introductory student difficulties in mechanics revealed by the Force Concept Inventory

    NASA Astrophysics Data System (ADS)

    Maries, Alexandru; Singh, Chandralekha

    2016-06-01

    The Force Concept Inventory (FCI) has been widely used to assess student understanding of introductory mechanics concepts by a variety of educators and physics education researchers. One reason for this extensive use is that many of the items on the FCI have strong distractor choices which correspond to students' alternate conceptions in mechanics. Instruction is unlikely to be effective if instructors do not know the common alternate conceptions of introductory physics students and explicitly take into account students' initial knowledge states in their instructional design. Here, we discuss research involving the FCI to evaluate one aspect of the pedagogical content knowledge of teaching assistants (TAs): knowledge of introductory student alternate conceptions in mechanics as revealed by the FCI. For each item on the FCI, the TAs were asked to identify the most common incorrect answer choice of introductory physics students. This exercise was followed by a class discussion with the TAs related to this task, including the importance of knowing student difficulties in teaching and learning. Then, we used FCI pretest and post-test data from a large population (˜900 ) of introductory physics students to assess the extent to which TAs were able to identify alternate conceptions of introductory students related to force and motion. In addition, we carried out think-aloud interviews with graduate students who had more than two semesters of teaching experience in recitations to examine how they reason about the task. We find that while the TAs, on average, performed better than random guessing at identifying introductory students' difficulties with FCI content, they did not identify many common difficulties that introductory physics students have after traditional instruction. We discuss specific alternate conceptions, the extent to which TAs are able to identify them, and results from the think-aloud interviews that provided valuable information about why TAs sometimes

  7. Microwave-assisted digestion using nitric acid for heavy metals and sulfated ash testing in active pharmaceutical ingredients.

    PubMed

    Pluhácek, T; Hanzal, J; Hendrych, J; Milde, D

    2016-04-01

    The monitoring of inorganic impurities in active pharmaceutical ingredients plays a crucial role in the quality control of the pharmaceutical production. The heavy metals and residue on ignition/sulfated ash methods employing microwave-assisted digestion with concentrated nitric acid have been demonstrated as alternatives to inappropriate compendial methods recommended in United States Pharmacopoeia (USP) and European Pharmacopoeia (Ph. Eur.). The recoveries using the heavy metals method ranged between 89% and 122% for nearly all USP and Ph. Eur. restricted elements as well as the recoveries of sodium sulfate spikes were around 100% in all tested matrices. The proposed microwave-assisted digestion method allowed simultaneous decomposition of 15 different active pharmaceutical ingredients with sample weigh up to 1 g. The heavy metals and sulfated ash procedures were successfully applied to the determination of heavy metals and residue on ignition/sulfated ash content in mycophenolate mofetil, nicergoline and silymarin. PMID:27209695

  8. Mechanism of APC/CCDC20 activation by mitotic phosphorylation

    PubMed Central

    Qiao, Renping; Weissmann, Florian; Yamaguchi, Masaya; Brown, Nicholas G.; VanderLinden, Ryan; Imre, Richard; Jarvis, Marc A.; Brunner, Michael R.; Davidson, Iain F.; Litos, Gabriele; Haselbach, David; Mechtler, Karl; Stark, Holger; Schulman, Brenda A.; Peters, Jan-Michael

    2016-01-01

    Chromosome segregation and mitotic exit are initiated by the 1.2-MDa ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome) and its coactivator CDC20 (cell division cycle 20). To avoid chromosome missegregation, APC/CCDC20 activation is tightly controlled. CDC20 only associates with APC/C in mitosis when APC/C has become phosphorylated and is further inhibited by a mitotic checkpoint complex until all chromosomes are bioriented on the spindle. APC/C contains 14 different types of subunits, most of which are phosphorylated in mitosis on multiple sites. However, it is unknown which of these phospho-sites enable APC/CCDC20 activation and by which mechanism. Here we have identified 68 evolutionarily conserved mitotic phospho-sites on human APC/C bound to CDC20 and have used the biGBac technique to generate 47 APC/C mutants in which either all 68 sites or subsets of them were replaced by nonphosphorylatable or phospho-mimicking residues. The characterization of these complexes in substrate ubiquitination and degradation assays indicates that phosphorylation of an N-terminal loop region in APC1 is sufficient for binding and activation of APC/C by CDC20. Deletion of the N-terminal APC1 loop enables APC/CCDC20 activation in the absence of mitotic phosphorylation or phospho-mimicking mutations. These results indicate that binding of CDC20 to APC/C is normally prevented by an autoinhibitory loop in APC1 and that its mitotic phosphorylation relieves this inhibition. The predicted location of the N-terminal APC1 loop implies that this loop controls interactions between the N-terminal domain of CDC20 and APC1 and APC8. These results reveal how APC/C phosphorylation enables CDC20 to bind and activate the APC/C in mitosis. PMID:27114510

  9. Mechanisms of Activation of Receptor Tyrosine Kinases: Monomers or Dimers

    PubMed Central

    Maruyama, Ichiro N.

    2014-01-01

    Receptor tyrosine kinases (RTKs) play essential roles in cellular processes, including metabolism, cell-cycle control, survival, proliferation, motility and differentiation. RTKs are all synthesized as single-pass transmembrane proteins and bind polypeptide ligands, mainly growth factors. It has long been thought that all RTKs, except for the insulin receptor (IR) family, are activated by ligand-induced dimerization of the receptors. An increasing number of diverse studies, however, indicate that RTKs, previously thought to exist as monomers, are present as pre-formed, yet inactive, dimers prior to ligand binding. The non-covalently associated dimeric structures are reminiscent of those of the IR family, which has a disulfide-linked dimeric structure. Furthermore, recent progress in structural studies has provided insight into the underpinnings of conformational changes during the activation of RTKs. In this review, I discuss two mutually exclusive models for the mechanisms of activation of the epidermal growth factor receptor, the neurotrophin receptor and IR families, based on these new insights. PMID:24758840

  10. Mechanisms of T Lymphocyte Activation Exposed by Super Resolution Microscopy

    NASA Astrophysics Data System (ADS)

    Campanello, Leonard; Losert, Wolfgang; Traver, Maria; Schaefer, Brian; York, Andrew; Schroff, Hari

    In order to avoid the deleterious consequences of an uncontrolled immune response, tight regulatory control of positive and negative regulators during lymphocyte activation is needed. Utilizing cutting-edge super-resolution imaging technologies in combination with quantitative image analysis we explore the interplay between positive and negative regulation in activated T lymphocytes and investigate whether intercellular signaling is possibly governed by the degradation of a complex intracellular structure called the POLKADOTS signalosome. In segmenting the POLKADOTS signalosome structure by the betweenness centrality of its 3D medial axis skeleton, it was discovered that autophagosomes, small degradative intracellular organelles, localize preferentially to the ends of the filamentous POLKADOTS signalosome. These results provide new insight into the mechanisms behind the complex regulatory process that govern T lymphocyte activation. This research was supported by an Irvington Postdoctoral Fellowship from the Cancer Research Institute (awarded to MT) and a U01 Grant from the National Institutes of Health (GM109887-01, awarded to BS and WL).

  11. Novel methods and self-reinforced composite materials for assessment and prevention of mechanically assisted corrosion in modular implants

    NASA Astrophysics Data System (ADS)

    Ouellette, Eric S.

    Novel methods for assessing the electrochemical and micromechanical performance of modular tapers were evaluated, and self-reinforced composite materials were developed for their potential to prevent the onset of mechanically assisted corrosion in modular taper devices. A study of the seating and taper locking mechanics of modular taper samples was conducted, and the effect on taper engagement strength of seating load, loading rate, taper moisture, and taper design/material combination was studied. The load-displacement behavior was captured during seating, and the subsequent pull off load was correlated to seating displacement, seating energy, and seating load. The primary factor affecting taper engagement strength was seating load, and loading rate and design/material factors did not have a significant impact on the quality of the taper engagement. Next, the effect of variation of 7 different design, material, and surgical factors on the fretting corrosion and micromechanical behavior during incremental cyclic fretting corrosion testing was examined using a design of experiments matrix. Seating load and head offset length were the most influential factors affecting fretting corrosion, with low seating loads and high head offsets giving rise to increased currents during sequentially incremented cyclic loads. Poly(ether ether ketone) (PEEK) fibers were produced, and the effects of varying draw down ratio, molecular weight, and post-spinning treatment on the structural and mechanical properties of the fibers were studied. Highly drawn fibers showed the highest increase in molecular orientation and mechanical properties. PEEK fibers were then utilized in the design and fabrication of self-reinforced composite PEEK (SRC-PEEK) thin film composites, and self-reinforced composite ultra-high molecular weight polyethylene (SRC-PE) produced from Spectra fiber was also introduced. Pin on disk studies were employed to understand the potential of both of these SRC materials to

  12. Preparation of highly photocatalytic active CdS/TiO2 nanocomposites by combining chemical bath deposition and microwave-assisted hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Li, Li; Wang, Lili; Hu, Tianyu; Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi

    2014-10-01

    CdS/TiO2 nanocomposites were prepared from Cd and Ti (1:1 M ratio) using cetyltrimethylammonium bromide by a two-step chemical bath deposition (CBD) and microwave-assisted hydrothermal synthesis (MAHS) method. A series of nanocomposites with different morphologies and activities were prepared by varying the reaction time in the MAHS (2, 4, and 6 h). The crystal structure, morphology, and surface physicochemical properties of the nanocomposites were characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption-desorption measurements. The results show that the CdS/TiO2 nanocomposites were composed of anatase TiO2 and hexagonal CdS phases with strong absorption in the visible region. The surface morphologies changed slightly with increasing microwave irradiation time, while the Brunauer-Emmett-Teller surface area increased remarkably. The photocatalytic degradation of methyl orange (MO) was investigated under UV light and simulated sunlight irradiation. The photocatalytic activity of the CdS/TiO2 (6 h) composites prepared by the MAHS method was higher than those of CdS, P25, and other CdS/TiO2 nanocomposites. The CdS/TiO2 (6 h) nanocomposites significantly affected the UV and microwave-assisted photocatalytic degradation of different dyes. To elucidate the photocatalytic reaction mechanism for the CdS/TiO2 nanocomposites, controlled experiments were performed by adding different radical scavengers.

  13. Microwave-assisted combustion synthesis of Ag/ZnO nanocomposites and their photocatalytic activities under ultraviolet and visible-light irradiation

    SciTech Connect

    Zhang, Dafeng; Pu, Xipeng; Li, Huaiyong; Yu, Young Moon; Shim, Jae Jeong; Cai, Peiqing; Kim, Sun Il; Seo, Hyo Jin

    2015-01-15

    Highlights: • Ag/ZnO nanocomposites were synthesized by a microwave-assisted combustion method. • Ag/ZnO nanocomposites exhibited improved photocatalytic activities under UV irradiation. • Poorer photocatalytic performances were obtained under visible-light irradiation. - Abstract: Ag/ZnO nanocomposites were synthesized by a rapid one-step microwave-assisted combustion method. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence and ultraviolet–visible spectrophotometry. XRD results showed that hexagonal ZnO and cubic Ag were obtained. Ag nanoparticles were chemically attached on the surface of ZnO. The decrease in the energy band gap of Ag/ZnO nanocomposites and the photoluminescence quenching were observed while the Ag content was increased. Furthermore, the introduction of Ag nanoparticles leads to significantly improved photocatalytic activities in the case of ultraviolet irradiation, but in the case of visible-light irradiation opposite results were obtained. The corresponding mechanism was discussed in detail.

  14. A common mechanism underlies stretch activation and receptor activation of TRPC6 channels

    PubMed Central

    Spassova, Maria A.; Hewavitharana, Thamara; Xu, Wen; Soboloff, Jonathan; Gill, Donald L.

    2006-01-01

    The TRP family of ion channels transduce an extensive range of chemical and physical signals. TRPC6 is a receptor-activated nonselective cation channel expressed widely in vascular smooth muscle and other cell types. We report here that TRPC6 is also a sensor of mechanically and osmotically induced membrane stretch. Pressure-induced activation of TRPC6 was independent of phospholipase C. The stretch responses were blocked by the tarantula peptide, GsMTx-4, known to specifically inhibit mechanosensitive channels by modifying the external lipid-channel boundary. The GsMTx-4 peptide also blocked the activation of TRPC6 channels by either receptor-induced PLC activation or by direct application of diacylglycerol. The effects of the peptide on both stretch- and diacylglycerol-mediated TRPC6 activation indicate that the mechanical and chemical lipid sensing by the channel has a common molecular mechanism that may involve lateral-lipid tension. The mechanosensing properties of TRPC6 channels highly expressed in smooth muscle cells are likely to play a key role in regulating myogenic tone in vascular tissue. PMID:17056714

  15. Mechanism of arsenate activation of mammalian phosphoglycerate mutase

    SciTech Connect

    Rea, D.W.; McWilliams, A.D.; Hass, L.F.

    1987-05-01

    Towne demonstrated that arsenate (As/sub i/) can replace D-glycerate-2,3-P/sub 2/ (2,3-DPG) as an activator for cofactor-dependent phosphoglycerate mutase (PGM). Arsenate activation was found to be accompanied by a lag phase which, over a period of several minutes, gradually evolved into a region of steady-state kinetics. The authors have verified and expanded Towne's findings through isotope exchange studies and kinetic analysis. In the absence of 2,3-DPG, reciprocal plots of PGM-catalyzed steady-state velocities versus As/sub i/ concentrations at different D-glycerate-3-P (3-PGA) levels yield a family of curves which suggest a ping-pong mechanism accompanied by double competitive substrate inhibition. Other experiments show that incubation of doubly-labelled 0.25 mM (U-/sup 14/C, /sup 32/P)-3-PGA with 20 mM As/sub i/ and PGM for several hrs. promotes the release of P/sub i/ with the concomitant formation of D-glycerate. Addition of 0.2 mM glycolate-2-P to the reaction medium accelerates the process. P/sub i/, but not vanadate, also promotes hydrolysis of 3-PGA, but to a much lesser extent than As/sub i/, even in the presence of glycolate-2-P. The pH optimum for 3-PGA phosphatase activity is 6.0-6.2. These and other findings suggest that As/sub i/ accelerates PGM catalysis by first forming 2-As-3-PGA which in turn forms phosphoenzyme (EP). Previous studies have shown that EP is the active form of PGM.

  16. Antibacterial mechanism and activities of black pepper chloroform extract.

    PubMed

    Zou, Lan; Hu, Yue-Ying; Chen, Wen-Xue

    2015-12-01

    Black pepper extracts reportedly inhibit food spoilage and food pathogenic bacteria. This study explored the antimicrobial activity of black pepper chloroform extract (BPCE) against Escherichia coli and Staphylococcus aureus. The antibacterial mechanism of BPCE was elucidated by analyzing the cell morphology, respiratory metabolism, pyruvic acid content, and ATP levels of the target bacteria. Scanning electron micrographs showed that the bacterial cells were destroyed and that plasmolysis was induced. BPCE inhibited the tricarboxylic acid pathway of the bacteria. The extract significantly increased pyruvic acid concentration in bacterial solutions and reduced ATP level in bacterial cells. BPCE destroyed the permeability of the cell membrane, which consequently caused metabolic dysfunction, inhibited energy synthesis, and triggered cell death. PMID:26604394

  17. Control of mechanically activated polymersome fusion: Factors affecting fusion

    SciTech Connect

    Henderson, Ian M.; Paxton, Walter F.

    2014-12-15

    Previously we have studied the mechanically-activated fusion of extruded (200 nm) polymer vesicles into giant polymersomes using agitation in the presence of salt. In this study we have investigated several factors contributing to this phenomenon, including the effects of (i) polymer vesicle concentration, (ii) agitation speed and duration, and iii) variation of the salt and its concentration. It was found that increasing the concentration of the polymer dramatically increases the production of giant vesicles through the increased collisions of polymersomes. Our investigations also found that increasing the frequency of agitation increased the efficiency of fusion, though ultimately limited the size of vesicle which could be produced due to the high shear involved. Finally it was determined that salt-mediation of the fusion process was not limited to NaCl, but is instead a general effect facilitated by the presence of solvated ionic compounds, albeit with different salts initiating fusion at different concentration.

  18. Control of mechanically activated polymersome fusion: Factors affecting fusion

    DOE PAGESBeta

    Henderson, Ian M.; Paxton, Walter F.

    2014-12-15

    Previously we have studied the mechanically-activated fusion of extruded (200 nm) polymer vesicles into giant polymersomes using agitation in the presence of salt. In this study we have investigated several factors contributing to this phenomenon, including the effects of (i) polymer vesicle concentration, (ii) agitation speed and duration, and iii) variation of the salt and its concentration. It was found that increasing the concentration of the polymer dramatically increases the production of giant vesicles through the increased collisions of polymersomes. Our investigations also found that increasing the frequency of agitation increased the efficiency of fusion, though ultimately limited the sizemore » of vesicle which could be produced due to the high shear involved. Finally it was determined that salt-mediation of the fusion process was not limited to NaCl, but is instead a general effect facilitated by the presence of solvated ionic compounds, albeit with different salts initiating fusion at different concentration.« less

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

    PubMed Central

    Takeda, Mamoru; Takehana, Shiori; Sekiguchi, Kenta; Kubota, Yoshiko; Shimazu, Yoshihito

    2016-01-01

    Changes to somatic sensory pathways caused by peripheral tissue, inflammation or injury can result in behavioral hypersensitivity and pathological pain, such as hyperalgesia. Resveratrol, a plant polyphenol found in red wine and various food products, is known to have several beneficial biological actions. Recent reports indicate that resveratrol can modulate neuronal excitability, including nociceptive sensory transmission. As such, it is possible that this dietary constituent could be a complementary alternative medicine (CAM) candidate, specifically a therapeutic agent. The focus of this review is on the mechanisms underlying the modulatory effects of resveratrol on nociceptive neuronal activity associated with pain relief. In addition, we discuss the contribution of resveratrol to the relief of nociceptive and/or pathological pain and its potential role as a functional food and a CAM. PMID:27727178

  20. Structure-activity analysis and antiprion mechanism of isoprenoid compounds.

    PubMed

    Hamanaka, Taichi; Nishizawa, Keiko; Sakasegawa, Yuji; Teruya, Kenta; Doh-ura, Katsumi

    2015-12-01

    The prion strain-specific mechanism by which normal prion protein is converted to abnormal prion protein remains largely unknown. This study found that insect juvenile hormone III reduced abnormal prion protein levels only in cells infected with the RML prion. We conducted a structure-activity analysis using juvenile hormone III biosynthetic intermediates in the isoprenoid pathway. Both farnesol and geranylgeraniol, the most potent inhibitors of abnormal prion protein formation, behaved in an RML prion-dependent fashion. Neither of them modified cellular and cell surface prion protein levels. Events downstream of this pathway include cholesterol biosynthesis and protein prenylation. However, neither of these isoprenoid compounds modified lipid raft microdomains and cellular cholesterol levels and neither affected the representative prenylated protein expression levels of prenylation pathways. Therefore, these isoprenoid compounds are a new class of prion strain-dependent antiprion compounds. They are useful for exploring strain-specific prion biology. PMID:26402376

  1. Low temperature activation of CO removal by O3-assisted catalysis.

    PubMed

    Jo, Sungkwon; Kim, Kwan-Tae; Lee, Dae Hoon; Song, Young-Hoon; Lee, Jae-Ok; Lee, Taewoo; Han, Hyun-Sik

    2014-12-16

    Catalytic CO oxidation was activated at low temperature by injecting O3 as an additive. It was empirically confirmed that CO removal rate was dramatically enhanced by supplying a small amount of O3, and the reaction temperature was almost half that required for CO oxidation when using a catalyst only. By optimizing the concentration of O3, catalytic CO oxidation could be achieved within 1 min at low operational temperature. The removal rate of CO was sensitive to the concentration of O3, and a deduced reaction mechanism is discussed to explain how catalytic CO oxidation is activated but subsequently deactivated at higher O3 concentration. Moreover, the presence of C3H8 and C3H6 were considered to evaluate the effects of each gas on the enhancement of CO removal rate by O3. Finally, the rate of CO removal was evaluated with increasing O3 concentration for practical applications such as the cold-start problem in automobile engines.

  2. FACT Assists Base Excision Repair by Boosting the Remodeling Activity of RSC.

    PubMed

    Charles Richard, John Lalith; Shukla, Manu Shubhdarshan; Menoni, Hervé; Ouararhni, Khalid; Lone, Imtiaz Nisar; Roulland, Yohan; Papin, Christophe; Ben Simon, Elsa; Kundu, Tapas; Hamiche, Ali; Angelov, Dimitar; Dimitrov, Stefan

    2016-07-01

    FACT, in addition to its role in transcription, is likely implicated in both transcription-coupled nucleotide excision repair and DNA double strand break repair. Here, we present evidence that FACT could be directly involved in Base Excision Repair and elucidate the chromatin remodeling mechanisms of FACT during BER. We found that, upon oxidative stress, FACT is released from transcription related protein complexes to get associated with repair proteins and chromatin remodelers from the SWI/SNF family. We also showed the rapid recruitment of FACT to the site of damage, coincident with the glycosylase OGG1, upon the local generation of oxidized DNA. Interestingly, FACT facilitates uracil-DNA glycosylase in the removal of uracil from nucleosomal DNA thanks to an enhancement in the remodeling activity of RSC. This discloses a novel property of FACT wherein it has a co-remodeling activity and strongly enhances the remodeling capacity of the chromatin remodelers. Altogether, our data suggest that FACT may acts in concert with RSC to facilitate excision of DNA lesions during the initial step of BER.

  3. FACT Assists Base Excision Repair by Boosting the Remodeling Activity of RSC.

    PubMed

    Charles Richard, John Lalith; Shukla, Manu Shubhdarshan; Menoni, Hervé; Ouararhni, Khalid; Lone, Imtiaz Nisar; Roulland, Yohan; Papin, Christophe; Ben Simon, Elsa; Kundu, Tapas; Hamiche, Ali; Angelov, Dimitar; Dimitrov, Stefan

    2016-07-01

    FACT, in addition to its role in transcription, is likely implicated in both transcription-coupled nucleotide excision repair and DNA double strand break repair. Here, we present evidence that FACT could be directly involved in Base Excision Repair and elucidate the chromatin remodeling mechanisms of FACT during BER. We found that, upon oxidative stress, FACT is released from transcription related protein complexes to get associated with repair proteins and chromatin remodelers from the SWI/SNF family. We also showed the rapid recruitment of FACT to the site of damage, coincident with the glycosylase OGG1, upon the local generation of oxidized DNA. Interestingly, FACT facilitates uracil-DNA glycosylase in the removal of uracil from nucleosomal DNA thanks to an enhancement in the remodeling activity of RSC. This discloses a novel property of FACT wherein it has a co-remodeling activity and strongly enhances the remodeling capacity of the chromatin remodelers. Altogether, our data suggest that FACT may acts in concert with RSC to facilitate excision of DNA lesions during the initial step of BER. PMID:27467129

  4. FACT Assists Base Excision Repair by Boosting the Remodeling Activity of RSC

    PubMed Central

    Ouararhni, Khalid; Roulland, Yohan; Ben Simon, Elsa; Kundu, Tapas; Hamiche, Ali; Angelov, Dimitar; Dimitrov, Stefan

    2016-01-01

    FACT, in addition to its role in transcription, is likely implicated in both transcription-coupled nucleotide excision repair and DNA double strand break repair. Here, we present evidence that FACT could be directly involved in Base Excision Repair and elucidate the chromatin remodeling mechanisms of FACT during BER. We found that, upon oxidative stress, FACT is released from transcription related protein complexes to get associated with repair proteins and chromatin remodelers from the SWI/SNF family. We also showed the rapid recruitment of FACT to the site of damage, coincident with the glycosylase OGG1, upon the local generation of oxidized DNA. Interestingly, FACT facilitates uracil-DNA glycosylase in the removal of uracil from nucleosomal DNA thanks to an enhancement in the remodeling activity of RSC. This discloses a novel property of FACT wherein it has a co-remodeling activity and strongly enhances the remodeling capacity of the chromatin remodelers. Altogether, our data suggest that FACT may acts in concert with RSC to facilitate excision of DNA lesions during the initial step of BER. PMID:27467129

  5. Self-burial mechanics of hygroscopically active awns

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  6. Determining soil enzyme activities for the assessment of fungi and citric acid-assisted phytoextraction under cadmium and lead contamination.

    PubMed

    Mao, Liang; Tang, Dong; Feng, Haiwei; Gao, Yang; Zhou, Pei; Xu, Lurong; Wang, Lumei

    2015-12-01

    Microorganism or chelate-assisted phytoextraction is an effective remediation tool for heavy metal polluted soil, but investigations into its impact on soil microbial activity are rarely reported. Consequently, cadmium (Cd)- and lead (Pb)-resistant fungi and citric acid (CA) were introduced to enhance phytoextraction by Solanum nigrum L. under varied Cd and Pb pollution levels in a greenhouse pot experiment. We then determined accumulation of Cd and Pb in S. nigrum and the soil enzyme activities of dehydrogenase, phosphatase, urease, catalase, sucrase, and amylase. Detrended canonical correspondence analysis (DCCA) was applied to assess the interactions between remediation strategies and soil enzyme activities. Results indicated that the addition of fungi, CA, or their combination enhanced the root biomass of S. nigrum, especially at the high-pollution level. The combined treatment of CA and fungi enhanced accumulation of Cd about 22-47 % and of Pb about 13-105 % in S. nigrum compared with the phytoextraction alone. However, S. nigrum was not shown to be a hyperaccumulator for Pb. Most enzyme activities were enhanced after remediation. The DCCA ordination graph showed increasing enzyme activity improvement by remediation in the order of phosphatase, amylase, catalase, dehydrogenase, and urease. Responses of soil enzyme activities were similar for both the addition of fungi and that of CA. In summary, results suggest that fungi and CA-assisted phytoextraction is a promising approach to restoring heavy metal polluted soil. PMID:26286803

  7. Determining soil enzyme activities for the assessment of fungi and citric acid-assisted phytoextraction under cadmium and lead contamination.

    PubMed

    Mao, Liang; Tang, Dong; Feng, Haiwei; Gao, Yang; Zhou, Pei; Xu, Lurong; Wang, Lumei

    2015-12-01

    Microorganism or chelate-assisted phytoextraction is an effective remediation tool for heavy metal polluted soil, but investigations into its impact on soil microbial activity are rarely reported. Consequently, cadmium (Cd)- and lead (Pb)-resistant fungi and citric acid (CA) were introduced to enhance phytoextraction by Solanum nigrum L. under varied Cd and Pb pollution levels in a greenhouse pot experiment. We then determined accumulation of Cd and Pb in S. nigrum and the soil enzyme activities of dehydrogenase, phosphatase, urease, catalase, sucrase, and amylase. Detrended canonical correspondence analysis (DCCA) was applied to assess the interactions between remediation strategies and soil enzyme activities. Results indicated that the addition of fungi, CA, or their combination enhanced the root biomass of S. nigrum, especially at the high-pollution level. The combined treatment of CA and fungi enhanced accumulation of Cd about 22-47 % and of Pb about 13-105 % in S. nigrum compared with the phytoextraction alone. However, S. nigrum was not shown to be a hyperaccumulator for Pb. Most enzyme activities were enhanced after remediation. The DCCA ordination graph showed increasing enzyme activity improvement by remediation in the order of phosphatase, amylase, catalase, dehydrogenase, and urease. Responses of soil enzyme activities were similar for both the addition of fungi and that of CA. In summary, results suggest that fungi and CA-assisted phytoextraction is a promising approach to restoring heavy metal polluted soil.

  8. Knowledge of and preferred sources of assistance for physical activity in a sample of urban Indigenous Australians

    PubMed Central

    Marshall, Alison L; Hunt, Julian; Jenkins, David

    2008-01-01

    Background To examine urban Indigenous Australians' knowledge of the current Physical Activity Guidelines (PAG) and identify their preferred sources of assistance or advice regarding physical activity. Method Self-completed questionnaire data were collected from 194 participants; the questionnaires sought information on standard demographics including an assessment of their perceived physical activity level relative to peers. Outcome measures were agreement with five statements from the current PAG and indicators of preferred sources of assistance or advice regarding physical activity. Results Most participants demonstrated excellent knowledge of the current PAG, with 92% to 88% of participants agreeing with the statements. Significantly more older participants (> 44 years) identified that 'blocks of 10 minutes of activity are OK' compared to younger participants (aged 18–44 years: 60%; X2 = 6.23; p = .04). Significantly more higher educated participants agreed (96%) that 'brisk walking for half an hour most days was good for health' compared to the less educated participants (85%; X2 = 8.08; p = .02). The most preferred source of physical activity advice identified by men was the GP/health professional (62% vs. 53%; men and women respectively, NS), while for women it was a group to be active with (60% vs. 42%; women and men respectively; X2 = 6.09; p = .01). Conclusion Urban Indigenous Australians have similar levels of knowledge regarding the PAG to non-Indigenous Australians. However, the option of accumulating 10-minute activity bouts needs to be better communicated to younger Indigenous people. Most participants expressed a preference for advice about physical activity to be delivered via health professionals, and groups to be active with. Indigenous and age-specific resources that promote the unique aspects of the current PAG (e.g., that vigorous exercise is not essential for health and blocks of 10 minutes of activity are OK) should be developed and

  9. Tungsten disulfide nanosheet and exonuclease III co-assisted amplification strategy for highly sensitive fluorescence polarization detection of DNA glycosylase activity.

    PubMed

    Zhao, Jingjin; Ma, Yefei; Kong, Rongmei; Zhang, Liangliang; Yang, Wen; Zhao, Shulin

    2015-08-01

    Herein, we introduced a tungsten disulfide (WS2) nanosheet and exonuclease III (Exo III) co-assisted signal amplification strategy for highly sensitive fluorescent polarization (FP) assay of DNA glycosylase activity. Two DNA glycosylases, uracil-DNA glycosylase (UDG) and human 8-oxoG DNA glycosylase 1 (hOGG1), were tested. A hairpin-structured probe (HP) which contained damaged bases in the stem was used as the substrate. The removal of damaged bases from substrate by DNA glycosylase would lower the melting temperature of HP. The HP was then opened and hybridized with a FAM dye-labeled single strand DNA (DP), generating a duplex with a recessed 3'-terminal of DP. This design facilitated the Exo III-assisted amplification by repeating the hybridization and digestion of DP, liberating numerous FAM fluorophores which could not be adsorbed on WS2 nanosheet. Thus, the final system exhibited a small FP signal. However, in the absence of DNA glycosylases, no hybridization between DP and HP was occurred, hampering the hydrolysis of DP by Exo III. The intact DP was then adsorbed on the surface of WS2 nanosheet that greatly amplified the mass of the labeled-FAM fluorophore, resulting in a large FP value. With the co-assisted amplification strategy, the sensitivity was substantially improved. In addition, this method was applied to detect UDG activity in cell extracts. The study of the inhibition of UDG was also performed. Furthermore, this method is simple in design, easy in implementation, and selective, which holds potential applications in the DNA glycosylase related mechanism research and molecular diagnostics.

  10. Tuning the activity of glutathione peroxidase mimics through intramolecular Se···N,O interactions: a DFT study incorporating solvent-assisted proton exchange (SAPE).

    PubMed

    Bayse, Craig A; Pavlou, Andrea

    2011-12-01

    Diaryl diselenide mimics of the antioxidant selenoprotein glutathione peroxidase (GPx) often incorporate intramolecular Se···N,O interactions to enhance their GPx-like activity. Although the strength of the interaction is defined by the Lewis basicity of the donating group and the strength of the Se-X bond, there is not a clear relationship between the interaction and the GPx-like activity. Density-functional theory and natural bond orbital (NBO) calculations are used to show the range of Se···N,O interactions for various functional groups. The strongest interactions are found for groups which stabilize the donor-acceptor interaction through aromatic stabilization. The activation barriers for the GPx-like mechanism of activity of several substituted areneselenols are calculated using DFT and solvent-assisted proton exchange (SAPE), a technique that incorporates networks of solvent molecules into the theoretical model to facilitate proton transfer between sites in the reactant and product. DFT-SAPE models show that, in addition to decreasing the barrier to oxidation of the selenol, Se···N,O interactions generally increase the barriers for selenenic acid reduction and selenol regeneration because the Se···N,O interaction must be broken for the reaction to proceed. Calculated activation barriers for the rate-determining step are consistent with the relative experimental GPx-like activities of a series of diaryl diselenides.

  11. 76 FR 5192 - BOEMRE Information Collection Activity: 1010-0170-Coastal Impact Assistance Program (CIAP...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-28

    ...: 1010-0170--Coastal Impact Assistance Program (CIAP), Extension of a Collection; Comment Request AGENCY... extension of an information collection (1010- 0170). SUMMARY: To comply with the Paperwork Reduction Act of..., Virginia 20170-4817. Please reference ICR 1010-0170 in your comment and include your name and...

  12. 75 FR 19659 - Bureau of Justice Assistance; Agency Information Collection Activities: Proposed Collection...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-15

    ... Bureau of Justice Assistance Application Form: Federal Law Enforcement Officers Congressional Badge of... Law Enforcement Officers Congressional Badge of Bravery. (3) The agency form number, if any, and the... required to respond, as well as a brief abstract: Primary: Law Enforcement officials. Abstract:...

  13. Language Development of Children Born Following Intracytoplasmic Sperm Injection (ICSI) Combined with Assisted Oocyte Activation (AOA)

    ERIC Educational Resources Information Center

    D'haeseleer, Evelien; Vanden Meerschaut, Frauke; Bettens, Kim; Luyten, Anke; Gysels, Hannelore; Thienpont, Ylenia; De Witte, Griet; Heindryckx, Björn; Oostra, Ann; Roeyers, Herbert; De Sutter, Petra; van Lierde, Kristiane

    2014-01-01

    Background: The effect of assisted reproduction technology (ART) on language development is still unclear. Moreover, different techniques are introduced at rapid pace and are not always accompanied by extensive follow-up programmes. Aims: To investigate the language development of 3-10-year-old children born following ART using intracytoplasmic…

  14. 78 FR 63972 - Agency Information Collection Activities; Comment Request; Student Assistance General Provisions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-25

    ... establish the standards to participate in the student financial aid assistance programs authorized by Title... establishes required information that must be provided to students, the financial responsibility requirements... to assure the Secretary that the integrity of the programs is protected from fraud and misuse...

  15. Peer-Assisted Learning in School Physical Education, Sport and Physical Activity Programmes: A Systematic Review

    ERIC Educational Resources Information Center

    Jenkinson, Kate. A.; Naughton, Geraldine; Benson, Amanda C.

    2014-01-01

    Background: Peer-assisted learning (PAL) is a teaching strategy utilised in both the general classroom and physical education. Through the interaction with same-age or cross-age peers, learning can occur across various domains. Purpose: This review aimed to identify school-based PAL interventions and assess the tutor training provided, as well as…

  16. Assistance Services for the Elderly. Reference Book and Student Activity Book.

    ERIC Educational Resources Information Center

    Texas Tech Univ., Lubbock. Home Economics Curriculum Center.

    These coordinated components focus on the career cluster of assistance services for the elderly. The reference book 1987 provide information needed by employees. Each chapter begins with competencies to develop and objectives to achieve. Within the text, bold-faced vocabulary terms are defined. Each chapter concludes with a content summary in the…

  17. College and University Waste Reduction and Recycled Product Procurement Activities, Barriers, and Assistance Strategies: Status Report.

    ERIC Educational Resources Information Center

    California Integrated Waste Management Board, Sacramento.

    In response to an official request for information and evaluation of solid waste production and management at California's public colleges and universities, this study examined existing conditions and barriers to solid waste reduction and recycled product procurement, and suggested assistance strategies. The examination found that these…

  18. Peer Assisted Learning in the Clinical Setting: An Activity Systems Analysis

    ERIC Educational Resources Information Center

    Bennett, Deirdre; O'Flynn, Siun; Kelly, Martina

    2015-01-01

    Peer assisted learning (PAL) is a common feature of medical education. Understanding of PAL has been based on processes and outcomes in controlled settings, such as clinical skills labs. PAL in the clinical setting, a complex learning environment, requires fresh evaluation. Socio-cultural theory is proposed as a means to understand educational…

  19. 24 CFR 570.210 - Prohibition on use of assistance for employment relocation activities.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... employment without changing their place of residence. In addition, LMAs are nonoverlapping and geographically... Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR COMMUNITY... product line of the business. (4) Significant loss of jobs. (i) A loss of jobs is significant if:...

  20. 24 CFR 570.210 - Prohibition on use of assistance for employment relocation activities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... employment without changing their place of residence. In addition, LMAs are nonoverlapping and geographically... Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR COMMUNITY... product line of the business. (4) Significant loss of jobs. (i) A loss of jobs is significant if:...

  1. [Study on mechanism for anti-hyperlipidemia efficacy of rhubarb through assistant analysis systems for acting mechanisms of traditional Chinese medicine].

    PubMed

    Du, Li; Yuan, Bin; Zhang, Bai-xia; Zhang, Yan-ling; Gao, Xiao-yan; Wang, Yun

    2015-10-01

    Rhubarb is a traditional Chinese medicine (TCM), wildly used in treating the disease of hyperlipidemia. However, its components are complicated, so that it is still difficult to clear the specific roles of its various components in blood lipids regulation in. So we decide to systematically study the anti- hyperlipidemia mechanism of rhubarb. We integrated multiple databases, based on entity grammar systems model, constructed molecular interaction network between the chemical constituents of rhubarb and hyperlipidemia. The network includes 231 nodes and 638 edges. Thus we infer the interactions of active targets and disease targets to clarify the anti-hyperlipidemia mechanism. And find that rhubarb can promote excretion of cholesterol; inhibit clotting factors and improve blood circulation; inhibit the release of inflammatory cytokines and maintain fat metabolism balance; inhibit cholesterol and triglyceride synthesis; and other ways to achieve lipid-lowering effect. Thus this study provides reference for novel drug development and component compatibility, and also gives a new way for the systematically study of acting mechanism of traditional Chinese medicine.

  2. Tactics for mechanized reasoning: a commentary on Milner (1984) ‘The use of machines to assist in rigorous proof’

    PubMed Central

    Gordon, M. J. C.

    2015-01-01

    Robin Milner's paper, ‘The use of machines to assist in rigorous proof’, introduces methods for automating mathematical reasoning that are a milestone in the development of computer-assisted theorem proving. His ideas, particularly his theory of tactics, revolutionized the architecture of proof assistants. His methodology for automating rigorous proof soundly, particularly his theory of type polymorphism in programing, led to major contributions to the theory and design of programing languages. His citation for the 1991 ACM A.M. Turing award, the most prestigious award in computer science, credits him with, among other achievements, ‘probably the first theoretically based yet practical tool for machine assisted proof construction’. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society. PMID:25750147

  3. Near infrared emission from molecule-like silver clusters confined in zeolite A assisted by thermal activation

    SciTech Connect

    Lin, Hui Imakita, Kenji; Rong Gui, Sa Chu; Fujii, Minoru

    2014-07-07

    Strong and broad near infrared (NIR) emission peaked at ~855 nm upon optimal excitation at 342 nm has been observed from molecule-like silver clusters (MLSCs) confined in zeolite A assisted by thermal activation. To the best of our knowledge, this is the first observation of NIR emission peaked at longer than 800 nm from MLSCs confined in solid matrices. The decay time of the NIR emission is over 10 μs, which indicates that it is a spin-forbidden transition. The ~855 nm NIR emission shows strong dependence on the silver loading concentration and the thermal activation temperature.

  4. Advances in the pharmacological activities and mechanisms of diosgenin.

    PubMed

    Chen, Yan; Tang, You-Mei; Yu, Su-Lan; Han, Yu-Wei; Kou, Jun-Ping; Liu, Bao-Lin; Yu, Bo-Yang

    2015-08-01

    Diosgenin, a well-known steroid sapogenin derived from plants, has been used as a starting material for production of steroidal hormones. The present review will summarize published literature concerning pharmacological potential of diosgenin, and the underlying mechanisms of actions. Diosgenin has shown a vast range of pharmacological activities in preclinical studies. It exhibits anticancer, cardiovascular protective, anti-diabetes, neuroprotective, immunomodulatory, estrogenic, and skin protective effects, mainly by inducing apoptosis, suppressing malignant transformation, decreasing oxidative stress, preventing inflammatory events, promoting cellular differentiation/proliferation, and regulating T-cell immune response, etc. It interferes with cell death pathways and their regulators to induce apoptosis. Diosgenin antagonizes tumor metastasis by modulating epithelial-mesenchymal transition and actin cytoskeleton to change cellular motility, suppressing degradation of matrix barrier, and inhibiting angiogenesis. Additionally, diosgenin improves antioxidant status and inhibits lipid peroxidation. Its anti-inflammatory activity is through inhibiting production of pro-inflammatory cytokines, enzymes and adhesion molecules. Furthermore, diosgenin drives cellular growth/differentiation through the estrogen receptor (ER) cascade and transcriptional factor PPARγ. In summary, these mechanistic studies provide a basis for further development of this compound for pharmacotherapy of various diseases. PMID:26253490

  5. Mechanisms of physical activity limitation in chronic lung diseases.

    PubMed

    Vogiatzis, Ioannis; Zakynthinos, George; Andrianopoulos, Vasileios

    2012-01-01

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

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

    PubMed

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

    2016-04-27

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

  7. Mechanical stress activates neurites and somata of myenteric neurons

    PubMed Central

    Kugler, Eva M.; Michel, Klaus; Zeller, Florian; Demir, Ihsan E.; Ceyhan, Güralp O.; Schemann, Michael; Mazzuoli-Weber, Gemma

    2015-01-01

    The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN) is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs) responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs) responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN), slowly (SAMEN), or ultra-slowly (USAMEN). The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut. PMID:26441520

  8. Structural mechanism of RuBisCO activation by carbamylation of the active site lysine

    PubMed Central

    Stec, Boguslaw

    2012-01-01

    Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is a crucial enzyme in carbon fixation and the most abundant protein on earth. It has been studied extensively by biochemical and structural methods; however, the most essential activation step has not yet been described. Here, we describe the mechanistic details of Lys carbamylation that leads to RuBisCO activation by atmospheric CO2. We report two crystal structures of nitrosylated RuBisCO from the red algae Galdieria sulphuraria with O2 and CO2 bound at the active site. G. sulphuraria RuBisCO is inhibited by cysteine nitrosylation that results in trapping of these gaseous ligands. The structure with CO2 defines an elusive, preactivation complex that contains a metal cation Mg2+ surrounded by three H2O/OH molecules. Both structures suggest the mechanism for discriminating gaseous ligands by their quadrupole electric moments. We describe conformational changes that allow for intermittent binding of the metal ion required for activation. On the basis of these structures we propose the individual steps of the activation mechanism. Knowledge of all these elements is indispensable for engineering RuBisCO into a more efficient enzyme for crop enhancement or as a remedy to global warming. PMID:23112176

  9. Optimization for ultrasound-assisted extraction of polysaccharides with antioxidant activity in vitro from the aerial root of Ficus microcarpa.

    PubMed

    Jiang, Changxing; Li, Xia; Jiao, Yunpeng; Jiang, Dingyun; Zhang, Ling; Fan, Benxia; Zhang, Qianghua

    2014-09-22

    In this study, optimization of ultrasound-assisted extraction and antioxidant activity of polysaccharides from the aerial root of Ficus microcarpa (FMPS) were investigated. The optimal conditions for extraction of FMPS were determined as followings: ultrasound power 200 W, ultrasound temperature 70°C, extraction temperature 74°C, liquid-solid ratio 35, extraction time 238 min, ultrasound time 49 min. The experimental yield of FMPS (3.44%) obtained under these conditions was well agreement with the value predicted by the model. In addition, Fourier transform-infrared spectroscopy and antioxidant activity assays revealed that FMPS were acidic polysaccharides and had strong Fe2+ chelating activity and moderate hydrogen peroxide scavenging effect. Further work on the purification, structure characterization and antioxidant activity in vivo of FMPS is in progress. PMID:24906722

  10. Purines, prostaglandins and peptides--nature and cellular mechanisms of action of local assist and assassin agents in the ovary.

    PubMed

    Behrman, H R; Aten, R F; Luborsky, J L; Polan, M L; Miller, J G; Soodak, L K

    1986-01-01

    The evidence for a paracrine, progonadotropic role of adenosine in ovarian cells is summarized along with a capsule review of the origin and mechanisms of release and action of adenosine in other tissues. Briefly, adenosine markedly amplified rat and human luteal cell cyclic AMP and progesterone accumulation in the presence, but not the absence, of LH. The site of action of adenosine was found to be intracellular, linked to its phosphorylation, which resulted in increased levels of ATP. In rat luteal cells, adenosine blocked the acute antigonadotropic (luteolytic) action of PGF2 alpha. In the follicle, adenosine release from granulosal cells appeared to be stimulated by FSH. Adenosine and a nonmetabolized adenosine analog, augmented FSH-dependent inhibition of oocyte maturation in the presence or absence of an adenosine transport inhibitor. Inhibition of oocyte maturation by adenosine thus appears to be mediated by extracellular purinergic receptors. Paracrine, antigonadotropic agents also appear to regulate ovarian function. For example, GnRH elicits antigonadotropic activity in rat granulosal and luteal cells. We describe a novel, GnRH-like, ovarian hormone (GLOH) which may be the physiological ligand whose action GnRH mimics in rat ovarian cells. This protein was shown to be distinctly different from GnRH and a variety of other cyclic and noncyclic peptides. PGF2 alpha is a well known leutolytic agent and a summary of the antigonadotropic mechanism of PGF2 alpha action in rat luteal cells is presented. In these cells, the action of GnRH (or possibly the GnRH-like protein) and PGF2 alpha are mediated by separate membrane receptors but they appeared to share the same intracellular second messenger. Evidence for a role of products of phosphoinositol as a mediator of these antigonadotropic agents is summarized. We suggest that the ultimate mediator of antigonadotropic agents is Ca2+ which is released in the luteal cell in response to the intracellular mediator of

  11. Path sampling calculation of methane diffusivity in natural gas hydrates from a water-vacancy assisted mechanism.

    PubMed

    Peters, Baron; Zimmermann, Nils E R; Beckham, Gregg T; Tester, Jefferson W; Trout, Bernhardt L

    2008-12-24

    Increased interest in natural gas hydrate formation and decomposition, coupled with experimental difficulties in diffusion measurements, makes estimating transport properties in hydrates an important technological challenge. This research uses an equilibrium path sampling method for free energy calculations [Radhakrishnan, R.; Schlick, T. J. Chem. Phys. 2004, 121, 2436] with reactive flux and kinetic Monte Carlo simulations to estimate the methane diffusivity within a structure I gas hydrate crystal. The calculations support a water-vacancy assisted diffusion mechanism where methane hops from an occupied "donor" cage to an adjacent "acceptor" cage. For pathways between cages that are separated by five-membered water rings, the free energy landscape has a high barrier with a shallow well at the top. For pathways between cages that are separated by six-membered water rings, the free energy calculations show a lower barrier with no stable intermediate. Reactive flux simulations confirm that many reactive trajectories become trapped in the shallow intermediate at the top of the barrier leading to a small transmission coefficient for these paths. Stable intermediate configurations are identified as doubly occupied off-pathway cages and methane occupying the position of a water vacancy. Rate constants are computed and used to simulate self-diffusion with a kinetic Monte Carlo algorithm. Self-diffusion rates were much slower than the Einstein estimate because of lattice connectivity and methane's preference for large cages over small cages. Specifically, the fastest pathways for methane hopping are arranged in parallel (nonintersecting) channels, so methane must hop via a slow pathway to escape the channel. From a computational perspective, this paper demonstrates that equilibrium path sampling can compute free energies for a broader class of coordinates than umbrella sampling with molecular dynamics. From a technological perspective, this paper provides one estimate for

  12. Final Report. SFAA No. DEFC02-98CH10961. Technical assistance for joint implementation and other supporting mechanisms and measures for greenhouse gas emissions mitigation

    SciTech Connect

    Knight, Denise

    2001-10-15

    IIEC, a division of CERF, has developed an extensive base of experience implementing activities that support climate action by developing USIJI projects in transitional countries within Asia, Latin America, Central and Eastern Europe, and southern Africa. IIEC has been able to provide a range of technical and policy assistance to governments and industry in support of sustainable energy use. IIEC continues to work in key countries with local partners to develop and implement energy efficiency policies and standards, develop site-specific projects, and assist governing bodies to establish national priorities and evaluation criteria for approving GHG-mitigation projects. As part of this project, IIEC focused on promoting a series of activities in Thailand and South Africa in order to identify GHG mitigation projects and work within the national approval process of those countries. The sections of this report outline the activities conducted in each country in order to achieve that goal.

  13. One-pot β-cyclodextrin-assisted extraction of active ingredients from Xue-Zhi-Ning basing its encapsulated ability.

    PubMed

    Zhang, Hui-Jie; Liu, Ya-Nan; Wang, Meng; Wang, Yue-Fei; Deng, Yan-Ru; Cui, Ming-Lei; Ren, Xiao-Liang; Qi, Ai-Di

    2015-11-01

    Xue-Zhi-Ning (XZN) is a traditional Chinese medicine formula, containing active ingredients with poor solubility in water, which has been demonstrated to be helpful for patients with hyperlipidemia. One-pot β-cyclodextrin (β-CD)-assisted extraction of active ingredients from XZN has been carried out to develop an efficient and eco-friendly extraction process. Five active compounds--rubrofusarin gentiobioside, 2,3,5,4'-tetrahydroxy-stilbene-2-O-β-D-glucoside, emodin, nuciferine and quercetin--were identified by UPLC/DAD/MS and used as indexes to evaluate the process optimized by an orthogonal test. The results showed that addition of β-CD significantly enhanced the extraction ratios of all five components. The enhancement of extraction ratios was positively correlated with the apparent formation constants between β-CD and the compounds. The study also showed that the stabilities and dissolution rates of the active ingredients were improved in the presence of β-CD. This one-pot β-cyclodextrin-assisted extraction has the potential to be applied in pharmaceutical preparations directly. PMID:26256368

  14. Highly sensitive fluorescence assay of T4 polynucleotide kinase activity and inhibition via enzyme-assisted signal amplification.

    PubMed

    Tao, Mangjuan; Zhang, Jing; Jin, Yan; Li, Baoxin

    2014-11-01

    DNA phosphorylation catalyzed by polynucleotide kinase (PNK) is an indispensable process in the repair, replication, and recombination of nucleic acids. Here, an enzyme-assisted amplification strategy was developed for the ultrasensitive monitoring activity and inhibition of T4 PNK. A hairpin oligonucleotide (hpDNA) was designed as a probe whose stem can be degraded from the 5' to 3' direction by lambda exonuclease (λ exo) when its 5' end is phosphorylated by PNK. So, the 3' stem and loop part of hpDNA was released as an initiator strand to open a molecular beacon (MB) that was designed as a fluorescence reporter, leading to a fluorescence restoration. Then, the initiator strand was released again by the nicking endonuclease (Nt.BbvCI) to hybridize with another MB, resulting in a cyclic reaction and accumulation of fluorescence signal. Based on enzyme-assisted amplification, PNK activity can be sensitively and rapidly detected with a detection limit of 1.0×10(-4)U/ml, which is superior to those of most existing approaches. Furthermore, the application of the proposed strategy for screening PNK inhibitors also demonstrated satisfactory results. Therefore, it provided a promising platform for monitoring activity and inhibition of PNK as well as for studying the activity of other nucleases.

  15. Mechanisms underlying obesity resistance associated with high spontaneous physical activity.

    PubMed

    Teske, J A; Billington, C J; Kotz, C M

    2014-01-01

    Obesity resistance due to elevated orexin signaling is accompanied by high levels of spontaneous physical activity (SPA). The behavioral and neural mechanisms underlying this observation have not been fully worked out. We determined the contribution of hypothalamic orexin receptors (OXRs) to SPA stimulated by orexin A (OXA), whether OXA-stimulated SPA was secondary to arousal and whether voluntary wheel running led to compensations in 24-h SPA. We further tested whether orexin action on dopamine one receptors (DA1R) in the substantia nigra (SN) plays an important role in the generation of SPA. To test this, SPA response was determined in lean and obese rats with cannulae targeted toward the rostral lateral hypothalamus (rLH) or SN. Sleep/wake states were also measured in rats with rLH cannula and electroencephalogram/electromyogram radiotelemetry transmitters. SPA in lean rats was more sensitive to antagonism of the OX1R and in the early response to the orexin 2 agonist. OXA increased arousal equally in lean and obese rodents, which is discordant from the greater SPA response in lean rats. Obesity-resistant rats ran more and wheel running was directly related to 24-h SPA levels. The OX1R antagonist, SB-334867-A, and the DA1R antagonist, SCH3390, in SN more effectively reduced SPA stimulated by OXA in obesity-resistant rats. These data suggest OXA-stimulated SPA is not secondary to enhanced arousal, propensity for SPA parallels inclination to run and that orexin action on dopaminergic neurons in SN may participate in the mediation of SPA and running wheel activity.

  16. The laser ablation model development of glass substrate cutting assisted with the thermal fracture and ultrasonic mechanisms

    NASA Astrophysics Data System (ADS)

    Huang, Kuo-Cheng; Hsiao, Wen-Tse; Hwang, Chi-Hung; Lin, Ru-Li; Andrew Yeh, Jer-Liang

    2015-04-01

    This study presents three hybrid processing models for cutting a glass substrate, and compares their cutting speeds. The three models are (I) thermal fracture cutting technology (TFCT)-assisted laser ablation, (II) ultrasonic-assisted laser ablation, and (III) ultrasonic and TFCT-assisted laser ablation. In the experiment, a 12 W 355 nm Nd:YVO4 laser system, a 40 W CO2 laser and an ultrasonic transducer were used to cut 3 mm thick soda-lime glasses. Lasers and ultrasonic transducers were used as heat sources and vibration sources, respectively. Results show that the surface morphology of the soda-lime glass sheet depends on the processing models. After cutting, the surface and cross-sectional morphology of glass substrate were observed using a portable digital microscope and residual stresses were also evaluated thanks to a photoelasticity instrument.

  17. Flexible and mechanical strain resistant large area SERS active substrates

    NASA Astrophysics Data System (ADS)

    Singh, J. P.; Chu, Hsiaoyun; Abell, Justin; Tripp, Ralph A.; Zhao, Yiping

    2012-05-01

    We report a cost effective and facile way to synthesize flexible, uniform, and large area surface enhanced Raman scattering (SERS) substrates using an oblique angle deposition (OAD) technique. The flexible SERS substrates consist of 1 μm long, tilted silver nanocolumnar films deposited on flexible polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) sheets using OAD. The SERS enhancement activity of these flexible substrates was determined using 10-5 M trans-1,2-bis(4-pyridyl) ethylene (BPE) Raman probe molecules. The in situ SERS measurements on these flexible substrates under mechanical (tensile/bending) strain conditions were performed. Our results show that flexible SERS substrates can withstand a tensile strain (ε) value as high as 30% without losing SERS performance, whereas the similar bending strain decreases the SERS performance by about 13%. A cyclic tensile loading test on flexible PDMS SERS substrates at a pre-specified tensile strain (ε) value of 10% shows that the SERS intensity remains almost constant for more than 100 cycles. These disposable and flexible SERS substrates can be integrated with biological substances and offer a novel and practical method to facilitate biosensing applications.

  18. Antibacterial activity and mechanism of berberine against Streptococcus agalactiae

    PubMed Central

    Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

    2015-01-01

    The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually. PMID:26191220

  19. Antibacterial activity and mechanism of berberine against Streptococcus agalactiae.

    PubMed

    Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

    2015-01-01

    The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually.

  20. Action 3:30: protocol for a randomized feasibility trial of a teaching assistant led extracurricular physical activity intervention

    PubMed Central

    2013-01-01

    Background Many children do not meet physical activity (PA) guidelines. Extracurricular programmes could provide a mechanism to increase the PA levels of primary-school-aged children. Teaching assistants (TAs) are a valuable resource in all UK primary schools and could be trained to delivery after-school PA programmes. The aim of this feasibility study is to examine whether the Action 3:30 PA intervention, which is delivered by TAs, could be effective in increasing the PA of Year 5 and 6 children. Methods/Design A feasibility trial will be conducted in 20 primary schools. Schools will be randomly assigned to intervention or control arms. Intervention schools will receive a 25-hour TA training programme for two TAs, a first-aid certificate course for two TAs; ongoing TA support; 40 one-hour session plans that can be delivered by TAs; Action 3:30 clubs that run twice a week for 20 weeks; and ten sets of parent information sheets that are distributed biweekly. All measures will be assessed at baseline (Time 0), at the end of the intervention period (Time 1) and four months after the intervention has ended (Time 2). As this is a feasibility study, our primary interest is in estimating the recruitment of schools and children, adherence to the intervention, and completeness of data collection for outcomes and costs. As the most likely primary outcome measure in a future definitive trial will be accelerometer-determined minutes of moderate-to-vigorous PA (MVPA) per day, participants will wear accelerometers for five days (including two weekend days). Several psychosocial variables that could act as mediators in a future trial will be assessed via a questionnaire. Process evaluations of the session attendance, perceived enjoyment and perceived exertion will be assessed during the intervention. At the end of the intervention period, qualitative assessments will be conducted to identify how the programme could be improved before proceeding to a larger trial. Discussion The

  1. Encoding of movement dynamics by Purkinje cell simple spike activity during fast arm movements under resistive and assistive force fields.

    PubMed

    Yamamoto, Kenji; Kawato, Mitsuo; Kotosaka, Shinya; Kitazawa, Shigeru

    2007-02-01

    It is controversial whether simple-spike activity of cerebellar Purkinje cells during arm movements encodes movement kinematics like velocity or dynamics like muscle activities. To examine this issue, we trained monkeys to flex or extend the elbow by 45 degrees in 400 ms under resistive and assistive force fields but without altering kinematics. During the task movements after training, simple-spike discharges were recorded in the intermediate part of the cerebellum in lobules V-VI, and electromyographic activity was recorded from arm muscles. Velocity profiles (kinematics) in the two force fields were almost identical to each other, whereas not only the electromyographic activities (dynamics) but also simple-spike activities in many Purkinje cells differed distinctly depending on the type of force field. Simple-spike activities encoded much larger mutual information with the type of force field than that with the residual small difference in the height of peak velocity. The difference in simple-spike activities averaged over the recorded Purkinje-cells increased approximately 40 ms before the appearance of the difference in electromyographic activities between the two force fields, suggesting that the difference of simple-spike activities could be the origin of the difference of muscle activities. Simple-spike activity of many Purkinje cells correlated with electromyographic activity with a lead of approximately 80 ms, and these neurons had little overlap with another group of neurons the simple-spike activity of which correlated with velocity profiles. These results show that simple-spike activity of at least a group of Purkinje cells in the intermediate part of cerebellar lobules V-VI encodes movement dynamics.

  2. Fast self-diffusion of ions in CH 3 NH 3 PbI 3 : the interstiticaly mechanism versus vacancy-assisted mechanism

    SciTech Connect

    Yang, Ji-Hui; Yin, Wan-Jian; Park, Ji-Sang; Wei, Su-Huai

    2016-01-01

    The stability of organic-inorganic halide perovskites is a major challenge for their applications and has been extensively studied. Among the possible underlying reasons, ion self-diffusion has been inferred to play important roles. While theoretical studies congruously support that iodine is more mobile, experimental studies only observe the direct diffusion of the MA ion and possible diffusion of iodine. The discrepancy may result from the incomplete understanding of ion diffusion mechanisms. With the help of first-principles calculations, we studied ion diffusion in CH3NH3PbI3 (MAPbI3) through not only the vacancy-assisted mechanisms presumed in previous theoretical studies, but also the neglected interstiticaly mechanisms. We found that compared to the diffusion through the vacancy-assisted mechanism, MA ion diffusion through the interstiticaly mechanism has a much smaller barrier which could explain experimental observations. For iodine diffusion, both mechanisms can yield relatively small barriers. Depending on the growth conditions, defect densities of vacancies and interstitials can vary and so do the diffusion species as well as diffusion mechanisms. Our work thus supports that both MA and iodine ion diffusion could contribute to the performance instability of MAPbI3. While being congruous with experimental results, our work fills the research gap by providing a full understanding of ion diffusion in halide perovskites.

  3. Proportional assist ventilation and neurally adjusted ventilatory assist.

    PubMed

    Kacmarek, Robert M

    2011-02-01

    Patient-ventilator synchrony is a common problem with all patients actively triggering the mechanical ventilator. In many cases synchrony can be improved by vigilant adjustments by the managing clinician. However, in most institutions clinicians are not able to spend the time necessary to ensure synchrony in all patients. Proportional assist ventilation (PAV) and neurally adjusted ventilatory assist (NAVA) were both developed to improve patient-ventilator synchrony by proportionally unloading ventilatory effort and turning control of the ventilatory pattern over to the patient. This paper discusses PAV's and NAVA's theory of operation, general process of application, and the supporting literature.

  4. Salvia officinalis for hot flushes: towards determination of mechanism of activity and active principles.

    PubMed

    Rahte, Sinikka; Evans, Richard; Eugster, Philippe J; Marcourt, Laurence; Wolfender, Jean-Luc; Kortenkamp, Andreas; Tasdemir, Deniz

    2013-06-01

    Herbal medicinal products are commonly used in alternative treatment of menopausal hot flushes. In a recent clinical study, Salvia officinalis tincture was found to reduce hot flush frequency and intensity. The aim of the current study was the investigation of the mechanism(s) responsible for the anti-hot flush activity of S. officinalis and determination of its active principle(s). The 66% ethanolic tincture, as well as the n-hexane, CHCl₃, and aqueous ethanolic subextracts obtained from the tincture were studied in vitro for two of the most relevant activities, estrogenicity and selective serotonin reuptake inhibition. Because of an increased risk of menopausal women to suffer from Alzheimer's disease, an in vitro acetylcholinesterase inhibition assay was also employed. No activity was observed in the selective serotonin reuptake inhibition or the acetylcholinesterase inhibition assays at the highest test concentrations. The tincture showed no estrogenic effects whereas the aqueous ethanolic subextract exhibited estrogenicity in the ERLUX assay with an EC₅₀ value of 64 µg/mL. Estrogenic activity-guided fractionation of the aqueous ethanolic subextract by a combination of reverse-phase vacuum liquid chromatography and gel chromatography identified luteolin-7-O-glucuronide (EC₅₀ 129 µg/mL) as the active component of the vacuum liquid chromatography fraction 4 (EC₅₀ 69 µg/mL). Luteolin-7-O-glucoside was identified as the putative estrogenic principle of the most potent minor fraction (7.6.7.6, EC₅₀ 0.7 µg/mL) obtained from the initial vacuum liquid chromatography fraction 7 (EC₅₀ 3 µg/mL). This study suggests the involvement of common and ubiquitous estrogenic flavonoids in the anti-hot flush effect of Salvia officinalis, a safe and commonly used herbal medicinal product during the menopause.

  5. Dog-assisted therapies and activities in rehabilitation of children with cerebral palsy and physical and mental disabilities.

    PubMed

    Elmacı, Dilek Tunçay; Cevizci, Sibel

    2015-05-12

    The aim of the present study was to evaluate dog-assisted therapies and activities in the rehabilitation of children with cerebral palsy and physical and mental disabilities who have difficulties in benefiting from well-being and health-improving services. This descriptive-explanatory study was conducted in disabled children of various ages between 2008 and 2011 by an experienced team in a private training and rehabilitation center in Antalya (Turkey). In this study, five study groups were formed among the children with physical and mental disabilities. During the therapy studies, three dogs were used. For each therapy group, the goals for the children and therapist were defined, and the activities were determined according to these goals. The entire study process was followed using audio-records and photographs of patients. The expected targets were reached in all study groups. The children who experienced fear, anxiety and difficulties due to their disabilities in daily life learned to cope with their anxieties and fears, set goals and make plans to achieve their aims. During this study, the children improved their abilities to use their bodies according to their capabilities. Accordingly, they improved their ability to develop empathy between themselves and a therapy dog, to receive and present help, and to communicate. The results of the present study revealed that dog-assisted therapies and activities can be a supportive method for routine treatment procedures in the rehabilitation of children with cerebral palsy and physical and mental disabilities.

  6. Dog-Assisted Therapies and Activities in Rehabilitation of Children with Cerebral Palsy and Physical and Mental Disabilities

    PubMed Central

    Tunçay Elmacı, Dilek; Cevizci, Sibel

    2015-01-01

    The aim of the present study was to evaluate dog-assisted therapies and activities in the rehabilitation of children with cerebral palsy and physical and mental disabilities who have difficulties in benefiting from well-being and health-improving services. This descriptive-explanatory study was conducted in disabled children of various ages between 2008 and 2011 by an experienced team in a private training and rehabilitation center in Antalya (Turkey). In this study, five study groups were formed among the children with physical and mental disabilities. During the therapy studies, three dogs were used. For each therapy group, the goals for the children and therapist were defined, and the activities were determined according to these goals. The entire study process was followed using audio-records and photographs of patients. The expected targets were reached in all study groups. The children who experienced fear, anxiety and difficulties due to their disabilities in daily life learned to cope with their anxieties and fears, set goals and make plans to achieve their aims. During this study, the children improved their abilities to use their bodies according to their capabilities. Accordingly, they improved their ability to develop empathy between themselves and a therapy dog, to receive and present help, and to communicate. The results of the present study revealed that dog-assisted therapies and activities can be a supportive method for routine treatment procedures in the rehabilitation of children with cerebral palsy and physical and mental disabilities. PMID:25985307

  7. Research on Social Stability Mechanisms Based on Activation Energy and Gradual Activation Reaction Theory

    NASA Astrophysics Data System (ADS)

    Ning, Miao; Gu, Jifa

    This paper draws a comparison between social stability and chemical reaction process, and brings forward the concept of “social temperature” and “activation energy of social agent”. It is considered that social temperature turns out to be the macro symptom of social average energy, and its unceasing up-climbing roots in the energy accumulation of “inferiorization” process of social system; that “activation energy of social agent” stands for the social energy or temperature where individuals or groups reach the limit of their psychological bearing ability. This paper, basing on above concepts, elaborates on and demonstrates the gradual activation reaction mechanisms of social stability by a lot of concrete examples. It is thought that there is a threshold value for social stability, and the society will be unstable if social temperature goes higher than this value; that the larger the social average activation energy is, the higher the temperature threshold value of social stability will be; and considering that different groups have different activation energy, those fragile groups with low activation energy are often the risk source which might pose a threat to social stability.

  8. The Self-Evaluation of the Project Activities by the Student Using an Assistant Tool for Thinking

    NASA Astrophysics Data System (ADS)

    Kiriyama, Satoshi; Hanabusa, Takao

    In the Center for Innovation and Creativity Development of the University of Tokushima, we have regarded the training to make plans as an important educational subject for young people, and we have taken measures. In advance of the last presentation of student-projects, we realized the idea of an assistant tool for thinking, and we made students analyze and evaluate their own project activities by using the tool. Moreover, the trial which pulls out an effective question from an audience was performed by applying the tool and by using a graphical presentation form. The Students estimated both trials as useful methods.

  9. Fluoride-assisted activation of calcium carbide: a simple method for the ethynylation of aldehydes and ketones.

    PubMed

    Hosseini, Abolfazl; Seidel, Daniel; Miska, Andreas; Schreiner, Peter R

    2015-06-01

    The fluoride-assisted ethynylation of ketones and aldehydes is described using commercially available calcium carbide with typically 5 mol % of TBAF·3H2O as the catalyst in DMSO. Activation of calcium carbide by fluoride is thought to generate an acetylide "ate"-complex that readily adds to carbonyl groups. Aliphatic aldehydes and ketones generally provide high yields, whereas aromatic carbonyls afford propargylic alcohols with moderate to good yields. The use of calcium carbide as a safe acetylide ion source along with economic amounts of TBAF·3H2O make this procedure a cheap and operationally simple method for the preparation of propargylic alcohols.

  10. The Volunteering-in-Place (VIP) Program: Providing meaningful volunteer activity to residents in assisted living with mild cognitive impairment.

    PubMed

    Klinedinst, N Jennifer; Resnick, Barbara

    2016-01-01

    The Volunteering-in-Place (VIP) Program was developed to provide individualized meaningful volunteer activities matched to interests and capabilities for older adults with MCI in assisted living. The purposes of this single-site pre-test/post-test pilot study were to (1) establish feasibility of the VIP Program based on treatment fidelity (design, treatment, delivery, enactment); and (2) evaluate preliminary efficacy via improvement in psychological health (depressive symptoms, usefulness, purpose, resilience, and life satisfaction) and decreased sedentary activity (survey and Fitbit) at 3 and 6 months. Ten residents participated. The majority was white, female and educated, and on average 88 years old. The VIP Program was feasible and most participants continued to volunteer at 6 months. There were non-significant improvements in depressive symptoms, usefulness, purpose, resilience and recreational physical activity. The results of this study provide support for the feasibility of the VIP Program. Further study is necessary to examine efficacy.

  11. Development of a Pre-Prototype Power Assisted Glove End Effector for Extravehicular Activity

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The purpose of this program was to develop an EVA power tool which is capable of performing a variety of functions while at the same time increasing the EVA crewmember's effectiveness by reducing hand fatigue associated with gripping tools through a pressurized EMU glove. The Power Assisted Glove End Effector (PAGE) preprototype hardware met or exceeded all of its technical requirements and has incorporated acoustic feedback to allow the EVA crewmember to monitor motor loading and speed. If this tool is to be developed for flight use, several issues need to be addressed. These issues are listed.

  12. Experimental Study of Diode Laser Cutting of Silicon by Means of Water Assisted Thermally Driven Separation Mechanism

    NASA Astrophysics Data System (ADS)

    Romero, P.; Otero, N.; Coto, I.; Leira, C.; González, A.

    A novel variant of thermal laser dicing of crystalline silicon has been studied in this paper, by using fluid assistance to improve the reliability, flexibility and operational window of the current process. High quality laser cutting of monocrystalline and polycrystalline silicon is demonstrated by using a diode laser focused on a 1 mm spot, assisted with the use of a water or glycerol layer, and resulting in Zero Kerf cuts with low total roughness and enabling freeform cutting. This variant process is compared with conventional thermal cleaving, with and without the use of an initial stress concentratior, as well as compared with optimized conventional approaches (ablation and gas assisted cutting). Besides the effective cutting speed, the laser induced damage is studied for each alternative, as well as the potential for photovoltaic applications on mono and multicrystalline silicon, is presented. Several parameters have been studied, to achieve highest effective speed values without damage in the surface of the wafer and a homogeneous cutting quality. The high quality, speed and flexibility of water-assisted direct diode induced thermal cutting are demonstrated.

  13. Incessant tachycardia in a patient with advanced heart failure and left ventricular assist device: What is the mechanism?

    PubMed

    Noheria, Amit; Mulpuru, Siva K; Noseworthy, Peter A; Asirvatham, Samuel J

    2016-01-01

    We present a case of incessant wide-complex tachycardia in a patient with left-ventricular assist device, and discuss the differential diagnosis with an in-depth analysis of the intracardiac tracings during the invasive electrophysiologic study, including interpretation of the relative timing of the fascicular signals during tachycardia and in sinus rhythm, and interpretation of pacing and entrainment maneuvers. PMID:27485564

  14. Mechanism of TiO2-assisted photocatalytic degradation of dyes under visible irradiation: photoelectrocatalytic study by TiO2-film electrodes.

    PubMed

    Yang, Juan; Chen, Chuncheng; Ji, Hongwei; Ma, Wanhong; Zhao, Jincai

    2005-11-24

    Photoelectrocatalytic degradation of various dyes under visible light irradiation with a TiO(2) nanoparticles electrode has been investigated to reveal the mechanism for TiO(2)-assisted photocatalytic degradation of dyes. The degradation of both cationic and anionic dyes at different biases, including the change in the degradation rate of the dyes and the photocurrent change with the bias potential, the degraded intermediates, the voltage-induced adsorption of dyes, the accumulation of electrons in the TiO(2) electrode, the effect of various additives such as benzoquinone (BQ) and N,N-dimethyl aniline (DMA), and the formation of active oxygen species such as O(2)(*-) and H(2)O(2) were examined by UV-visible spectroscopy, HPLC, TOC, and spin-trap ESR spectrometry. It was found that the dyes could controllably interact with the TiO(2) surface by external bias changes and charging of dyes. The cationic dyes such as RhB and MG underwent efficient mineralization at negative bias, but the N-dealkylation process predominated at positive bias under visible light irradiation. The discolorations of the anionic dyes SRB and AR could not be accelerated significantly at either negative or positive bias. At a negative bias of -0.6 V vs SCE, O(2)(*-) and dye(*+) were formed simultaneously at the electrode/electrolyte interface during degradation of cationic RhB. In the case of anionic dyes, however, it is impossible for the O(2)(*-) and dye cationic radical to coexist at the electrode/electrolyte surface. Experimental results imply both the superoxide anionic radical and the dye cationic radical are essential to the mineralization of the dyes under visible light-induced photocatalytic conditions.

  15. Insights into the phosphatase and the synthase activities of human bisphosphoglycerate mutase: a quantum mechanics/molecular mechanics simulation.

    PubMed

    Chu, Wen-Ting; Zheng, Qing-Chuan; Zhang, Hong-Xing

    2014-03-01

    Bisphosphoglycerate mutase (BPGM) is a multi-activity enzyme. Its main function is to synthesize the 2,3-bisphosphoglycerate, the allosteric effector of hemoglobin. This enzyme can also catalyze the 2,3-bisphosphoglycerate to the 3-phosphoglycerate. In this study, the reaction mechanisms of both the phosphatase and the synthase activities of human bisphosphoglycerate mutase were theoretically calculated by using the quantum mechanics/molecular mechanics method based on the metadynamics and umbrella sampling simulations. The simulation results not only show the free energy curve of the phosphatase and the synthase reactions, but also reveal the important role of some residues in the active site. Additionally, the energy barriers of the two reactions indicate that the activity of the synthase in human bisphosphoglycerate mutase is much higher than that of the phosphatase. The estimated reaction barriers are consistent with the experimental data. Therefore, our work can give important information to understand the catalytic mechanism of the bisphosphoglycerate mutase family.

  16. Ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. and their antioxidant activity.

    PubMed

    Muñiz-Márquez, Diana B; Martínez-Ávila, Guillermo C; Wong-Paz, Jorge E; Belmares-Cerda, Ruth; Rodríguez-Herrera, Raúl; Aguilar, Cristóbal N

    2013-09-01

    Bay leaves (BL) (Laurus nobilis L., Family: Laureceae) are traditionally used to treat some symptoms of gastrointestinal problems, such as epigastric bloating, impaired digestion, eructing and flatulence. These biological properties are mainly attributed to its phenolic compounds. In this paper, ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. (Laureceae) was studied. Effects of several experimental factors, such as sonication time, solid/liquid ratio and concentration of solvent on extraction of phenolic compounds were evaluated through a randomized complete block design with factorial treatment arrangement (3(3)). The best extraction conditions were: 1g plant sample with 12 mL of 35% ethanol, for 40 min, obtaining a yield of phenolic compounds of 17.32±1.52 mg g(-1) of plant. In addition, free radical-scavenging potential of DPPH and lipid oxidation inhibition, by linoleic acid peroxidation of the selected extract was measured in order to evidence their antioxidant properties. Results indicated that high amounts of phenolic compounds can be extracted from L. nobilis by ultrasound-assisted extraction technology. PMID:23523026

  17. Revisiting the mechanism of photocatalytic activities in N-doped TiO2

    NASA Astrophysics Data System (ADS)

    Umezawa, Naoto; Ye, Jinhua

    2012-02-01

    Photocatalysis possesses a great potential for environmental remediation and fuel production [1]. Nitrogen doped TiO2 is a well-known visible-light sensitive photocatalyst where deep impurity states associated with substitutional nitrogen at oxygen sites (NO) are believed to be the source of the red shift in photo-absorption edge. However, such a deep level should trap hole carriers, degrading oxidation process. The contradiction between the deep NO level and rather a high oxidation power of N-doped TiO2 has been an unsolved puzzle. Here, we propose a convincing mechanism which successfully solves the riddle. NO strongly binds with a titanium atom at an interstitial site, forming a defect-impurity band, which consists of bonding and anti-bonding states of nitrogen p and titanium d and narrows the band gap. Such a newly formed band, which is connected to the valence band maximum of the host TiO2, becomes the migration path of photo-induced hole carriers, assisting carrier transfer to the surface. This clearly explains the photocatalytic activity of N-doped TiO2 both for the visible-light absorption and the oxidation reaction. [1] Hua Tong, Shuxin Ouyang, Yingpu Bi, Naoto Umezawa, Mitsutake Oshikiri, and Jinhua Ye, Advanced Materials DOI: 10.1002/adma.20110275

  18. Avocado Proanthocyanidins as a Source of Tyrosinase Inhibitors: Structure Characterization, Inhibitory Activity, and Mechanism.

    PubMed

    Chai, Wei-Ming; Wei, Man-Kun; Wang, Rui; Deng, Rong-Gen; Zou, Zheng-Rong; Peng, Yi-Yuan

    2015-08-26

    Proanthocyanidins were purified from avocado (Persea americana) fruit, and their structures were analyzed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and high-performance liquid chromatography-electrospray ionization-QTRAP mass spectrometry (HPLC-ESI-QTRAP MS) techniques. The results obtained from mass spectrometry (MS) analysis demonstrated that the proanthocyanidins were homo- and heteropolymers of procyanidins, prodelphinidins, propelargonidins, and procyanidin gallate. From the enzyme analysis, the results showed that they could inhibit the monophenolase and diphenolase activities of tyrosinase. The inhibition mechanism of the proanthocyanidins on the enzyme was further studied, and the results indicated that they were reversible and competitive inhibitors. Finally, the results acquired from molecular docking, fluorescence quenching, and copper ion interacting tests revealed that adjacent hydroxyl groups on the B ring of proanthocyanidins could chelate the dicopper catalytic center of the enzyme. In addtion, proanthocyanidins were proven to be an efficient quencher of substrates. This study would lay a scientific foundation for their use in agriculture, food, and nutrition industries. PMID:26259028

  19. Avocado Proanthocyanidins as a Source of Tyrosinase Inhibitors: Structure Characterization, Inhibitory Activity, and Mechanism.

    PubMed

    Chai, Wei-Ming; Wei, Man-Kun; Wang, Rui; Deng, Rong-Gen; Zou, Zheng-Rong; Peng, Yi-Yuan

    2015-08-26

    Proanthocyanidins were purified from avocado (Persea americana) fruit, and their structures were analyzed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and high-performance liquid chromatography-electrospray ionization-QTRAP mass spectrometry (HPLC-ESI-QTRAP MS) techniques. The results obtained from mass spectrometry (MS) analysis demonstrated that the proanthocyanidins were homo- and heteropolymers of procyanidins, prodelphinidins, propelargonidins, and procyanidin gallate. From the enzyme analysis, the results showed that they could inhibit the monophenolase and diphenolase activities of tyrosinase. The inhibition mechanism of the proanthocyanidins on the enzyme was further studied, and the results indicated that they were reversible and competitive inhibitors. Finally, the results acquired from molecular docking, fluorescence quenching, and copper ion interacting tests revealed that adjacent hydroxyl groups on the B ring of proanthocyanidins could chelate the dicopper catalytic center of the enzyme. In addtion, proanthocyanidins were proven to be an efficient quencher of substrates. This study would lay a scientific foundation for their use in agriculture, food, and nutrition industries.

  20. Three Activities To Assist Biology Teachers in Presenting Conceptually Difficult Topics.

    ERIC Educational Resources Information Center

    Taylor, Neil; Tulip, David

    1997-01-01

    Outlines three activities for different areas of biology that can serve as motivators for students or as demonstrations. Each activity is easy to organize and uses available materials. Topics include evolution, anaerobic respiration, and heat loss. (DDR)