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Sample records for voltage stability evaluation

  1. Wind Power Plant Voltage Stability Evaluation: Preprint

    SciTech Connect

    Muljadi, E.; Zhang, Y. C.

    2014-09-01

    Voltage stability refers to the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition. Voltage stability depends on a power system's ability to maintain and/or restore equilibrium between load demand and supply. Instability that may result occurs in the form of a progressive fall or rise of voltages of some buses. Possible outcomes of voltage instability are the loss of load in an area or tripped transmission lines and other elements by their protective systems, which may lead to cascading outages. The loss of synchronism of some generators may result from these outages or from operating conditions that violate a synchronous generator's field current limit, or in the case of variable speed wind turbine generator, the current limits of power switches. This paper investigates the impact of wind power plants on power system voltage stability by using synchrophasor measurements.

  2. Experimental Evaluation of DG's Dynamic Voltage Support Capability Improving Short-Term Voltage Stability on Power System Loads

    NASA Astrophysics Data System (ADS)

    Ueda, Tomoyuki; Komami, Shintaro

    High DG penetration will seriously spoil short-term voltage stability of load in bulk power system. Simulation results on previous studies by the authors have shown that dynamic voltage support (DVS) capability of DG improves the stability, but experimental evaluation doesn't exist yet. This paper presents the effect of DVS capability of DG on an experimental circuit, which consists of an induction motor, a resistance load, and a compensation capacitor behind a reactance. First, an experimental set up that causes voltage instability without DVS is made up. Second, an improvement in DG inverter control is made to realize low voltage ride-through (LVRT) capability and DVS capability, and the DG's performance is confirmed by voltage sag tests. Finally, the tests on the experimental set up demonstrate that DVS capability improves greatly short-term voltage stability of power system loads, and the experimental results give good agreement with simulation results.

  3. Voltage stability analysis in the new deregulated environment

    NASA Astrophysics Data System (ADS)

    Zhu, Tong

    Nowadays, a significant portion of the power industry is under deregulation. Under this new circumstance, network security analysis is more critical and more difficult. One of the most important issues in network security analysis is voltage stability analysis. Due to the expected higher utilization of equipment induced by competition in a power market that covers bigger power systems, this issue is increasingly acute after deregulation. In this dissertation, some selected topics of voltage stability analysis are covered. In the first part, after a brief review of general concepts of continuation power flow (CPF), investigations on various matrix analysis techniques to improve the speed of CPF calculation for large systems are reported. Based on these improvements, a new CPF algorithm is proposed. This new method is then tested by an inter-area transaction in a large inter-connected power system. In the second part, the Arnoldi algorithm, the best method to find a few minimum singular values for a large sparse matrix, is introduced into the modal analysis for the first time. This new modal analysis is applied to the estimation of the point of voltage collapse and contingency evaluation in voltage security assessment. Simulations show that the new method is very efficient. In the third part, after transient voltage stability component models are investigated systematically, a novel system model for transient voltage stability analysis, which is a logical-algebraic-differential-difference equation (LADDE), is offered. As an example, TCSC (Thyristor controlled series capacitors) is addressed as a transient voltage stabilizing controller. After a TCSC transient voltage stability model is outlined, a new TCSC controller is proposed to enhance both fault related and load increasing related transient voltage stability. Its ability is proven by the simulation.

  4. Dynamic Analysis of Power System Voltage Stability.

    NASA Astrophysics Data System (ADS)

    Gebreselassie, Assefa

    This thesis investigates the effects of loads and voltage regulators on the dynamic voltage stability of power systems. The analysis focuses on the interactions of machine flux dynamics with loads and voltage control devices. The results are based on eigenvalue analysis of the linearized models and time simulation of the nonlinear models, using models from the Power System Toolbox, a Matlab -based package for the simulation and small signal analysis of nonlinear power systems. The voltage stability analysis results are developed using a single machine single load system with typical machine and network parameters and the NPCC 10-machine system. Dynamic models for generators, exciters and loads are used. The generator is modeled with a pair of poles and one damper circuit in both the d-axis and the q-axis. Saturation effects are included in the model. The IEEE Type DC1 DC commutator exciter model is used for all the exciters. Five different types of loads: constant impedance, constant current, constant power, a first order induction motor model (slip model) and a third order induction motor model (slip-flux model) are considered. The modes of instability and the stability limits of the different representation of loads are examined for two different operating modes of the exciters. The first, when all the exciters are on automatic control and the second when some exciters are on manual control. Modal participation factors are used to determine the characteristics of the critical modes. The characteristics of the unstable modes are verified by performing time simulation of the nonlinear models. Oscillatory and non-oscillatory instabilities are experienced by load buses when all the exciters are on automatic control and some exciters are on manual control respectively, for loads which are predominantly constant power and induction motors. It is concluded that the mode of instability does not depend on the type of loads but on the operating condition of the exciters. However, the severity of instability depends on the type of loads. Hence in dynamic voltage analysis, to arrive at a meaningful conclusion, the operating conditions of the exciters and the exact load composition should be taken into account.

  5. Memristor-integrated voltage-stabilizing supercapacitor system.

    PubMed

    Liu, Bin; Liu, Boyang; Wang, Xianfu; Wu, Xinghui; Zhao, Wenning; Xu, Zhimou; Chen, Di; Shen, Guozhen

    2014-08-01

    Voltage-stabilized supercapacitors: A single supercapacitor formed with PCBM/Pt/IPS nanorod-array electrodes is designed and delivers enhanced areal capacitance, capacitance retention, and excellent electrical stability under bending, while a significant voltage-decrease is observed during the discharging process. Once integrated with the memristor, the memristor-integrated supercapacitor systems deliver an extremely low voltage-drop, indicating greatly enhanced voltage-stabilizing features. PMID:24805149

  6. Voltage stability and controllability indices for multimachine power systems

    SciTech Connect

    Vournas, C.D.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  7. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    PubMed

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  8. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    PubMed Central

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  9. A study on threshold voltage stability of low operating voltage organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Padma, N.; Sen, Shaswati; Sawant, Shilpa N.; Tokas, R.

    2013-08-01

    A low operating voltage (<2 V) organic field-effect transistor (OFET) using phenylhexyltrichlorosilane (PTS) self-assembled monolayer (SAM) dielectric and copper phthalocyanine (CuPc) as semiconductor with improved mobility (0.035 cm2 V-1 s-1) and threshold voltage stability was demonstrated. This device showed better performance when compared to an OFET with octyltrichlorosilane (OTS-8) SAM dielectric. The improved mobility was attributed to the 2D growth mode of CuPc on PTS SAM because of surface energy matching between the two, whereas CuPc film on OTS-8 showed a 3D growth mode with larger grain boundary density. The higher threshold voltage stability of OFETs on PTS SAM was attributed to the efficient coverage and screening of trap centres at dielectric/semiconductor interface due to stronger intermolecular linking and formation of closely packed surface by the bulky phenyl end groups. Decrease in grain boundaries offered by 2D growth of CuPc for electron and hole trapping was also found to be another reason for improved threshold voltage stability. The results indicated that the nature of the end group of SAM dielectric, surface chemistry of dielectric and initial growth mode of semiconductors are all responsible for improvement in threshold voltage stability and enhanced performance of OFET.

  10. High voltage stability performance of a gamma ray detection device

    SciTech Connect

    Abdullah, Nor Arymaswati; Lombigit, Lojius; Rahman, Nur Aira Abd

    2014-02-12

    An industrial grade digital radiation survey meter device is currently being developed at Malaysian Nuclear Agency. This device used a cylindrical type Geiger Mueller (GM) which acts as a detector. GM detector operates at relatively high direct current voltages depend on the type of GM tube. This thin/thick walled cylindrical type of GM tube operates at 450-650 volts range. Proper value and stability performance of high voltage are important parameters to ensure that this device give a reliable radiation dose measurement. This paper will present an assessment of the stability and performance of the high voltage supply for radiation detector. The assessment is performed using System Identification tools box in MATLAB and mathematical statistics.

  11. Application of SMES in wind farm to improve voltage stability

    NASA Astrophysics Data System (ADS)

    Shi, J.; Tang, Y. J.; Ren, L.; Li, J. D.; Chen, S. J.

    2008-09-01

    For the wind farms introducing doubly fed induction generators (DFIGs), voltage stability is an essential issue which influences their widely integration into the power grid. This paper proposes the application of superconducting magnetic energy storage (SMES) in the power system integrated with wind farms. SMES can control the active and reactive power flow, realizing the operation in four quadrants independently. The introducing of SMES can smooth the output power flow of the wind farms, and supply dynamic voltage support. Using MATLAB/SIMULINK, the models of the DFIG, the power grid connected and the SMES are created. Simulation results show that the voltage stability of the power system integrated with wind farms can be improved considerably.

  12. Online Assessment of Voltage Stability in Power Systems with PMUs

    NASA Astrophysics Data System (ADS)

    Chitare, Prasad Bhagwat; Murthy Balijepalli, V. S. K.; Khaparde, S. A.

    2013-05-01

    Abstract: For the assessment of voltage instability which comprises the detection of voltage instability and identification of critical buses, two indices namely, system wide Qtax, and bus-specific qtax, are proposed. The Qtax, based on the sensitivity of the reactive power injections to the loading in the system provides early detection of impending voltage instability. The computed qtax indices identify the critcal buses among the load buses in the system. The identified critical buses provided optimal lacations for the corrective control actions for averting voltage instability. Additionally, for voltage stability monitoring, determining the poing of exhaustion of the reactive reserves in system is also crucial. This is addressed by proposed Q-Monitoring Index (QMI), which is the ratio of the reactive component of the source current to the sink current that flows through the adjacent transmission line. These proposed indices together can provide early indication to impending voltage instability. This has been illustrated on IEEE-39 bus system. The reactive support on identified critical buses results in maximum increase in the loadability of the system.

  13. Fast voltage stability assessment and reinforcement in an interconnected power system

    NASA Astrophysics Data System (ADS)

    Hsiao, Wen-Ta

    1998-12-01

    It is believed that voltage stability analysis will be more difficult due to the full utilization of transmission systems and the growth of inter-utility power transfer. An online voltage stability analyzing system which can be incorporated into the EMS to deal with the threats of suddenly arising voltage collapses is presented. Operating margin prediction, voltage stability assessment and reinforcement are three major functions. Two predicting methods are proposed to calculate the operating margin according to current operating condition and the anticipative system state. A fast risk indicator based on the saddle-node bifurcation theory is designed to predict the proximity of a system to voltage collapse. A novel CPF method which can trace the power flow solution path through the nose point without notorious numerical difficulties is presented. Speed is the advantage of former method, while accuracy is the important feature of latter one. Voltage stability assessment is required to predict steady-state conditions of a system following a large number of anticipated transmission branch or generator outages. An efficient and simple method based on voltage sensitivity changing rates is proposed for quickly identify the weak buses in a large-scale system. An effective contingency selection function relying on search algorithms built into power flow solutions is designed to filter out most of harmless contingencies for system operators who are working with rapidly changing load/generation patterns and a wide variety of operating conditions. A contingency evaluation function having the ability to deal with real-time numerous contingencies in a very short period of time is utilized to find high-severity contingencies. Var compensation and load shedding are two remedial measures of reinforcement function. Suitable var compensation scheme has three contributions: extending operating margin to avoid voltage collapses, fully utilizing the transmission infrastructure to earn economic benefits, and reducing the number of must-run units to eliminate monopoly profits. A load shedding method is designed to provide protection from fatal voltage collapses occurring outside of prior planning and operating studies. Two practical large-scale power systems and their interconnections are used to study voltage stability throughout this dissertation.

  14. Modal Voltage Stability Analysis of Multi-infeed HVDC System Considering its Control Systems

    NASA Astrophysics Data System (ADS)

    Wu, Guohong; Minakawa, Tamotsu; Hayashi, Toshiyuki

    This work presents a method for investigating the voltage stability of multi-infeed HVDC systems, which is based on the eigenvalue decomposition technique known as modal analysis. In this method, the eigenvalue of linearized steady-state system power-voltage equations are computed to evaluate the long-term voltage stability. The contributions of this work to modal analysis method are control systems of HVDC system, such as an Automatic Power Regulator (APR) and an Automatic (DC) Current Regulator (ACR) on its rectifier side and a changeover between an Automatic (DC) Voltage Regulator (AVR) and an Automatic extinction advance angle Regulator (A?R) modes on its inverter side, were taken into account, and the formularization for modal analysis considering not only these control systems of HVDC system but also generator and load characteristics was fulfilled and presented in this paper. The application results from an AC/DC model power system with dual HVDC systems verified the efficiency of the proposed method and quantitatively illustrated the influence of control systems of HVDC system on AC/DC system long-term voltage stability.

  15. Test Evaluation of a Reduced-Voltage Induction Motor Controller.

    SciTech Connect

    Portland General Energy Systems.

    1994-07-01

    This project was designed to test the performance of a motor controller called the ``Electro Guard`` that was distributed by Conservation Products Manufacturing. This motor controller was marketed as a new generation motor controller that saves electric energy by reducing voltage to match motor load and to improve power factor. This project included laboratory testing and had the option of field demonstrations to evaluate energy savings and cost effectiveness, equipment stability and reliability, appropriate applications, level of induced harmonic currents, maintenance soft start benefits, and potential regional electrical energy savings.

  16. Strategies for Voltage Control and Transient Stability Assessment

    SciTech Connect

    Hiskens, Ian A.

    2013-09-25

    As wind generation grows, its influence on power system performance will becoming increasingly noticeable. Wind generation di#11;ffers from traditional forms of generation in numerous ways though, motivating the need to reconsider the usual approaches to power system assessment and performance enhancement. The project has investigated the impact of wind generation on transient stability and voltage control, identifying and addressing issues at three distinct levels of the power system: 1) at the device level, the physical characteristics of wind turbine generators (WTGs) are quite unlike those of synchronous machines, 2) at the wind-farm level, the provision of reactive support is achieved through coordination of numerous dissimilar devices, rather than straightforward generator control, and 3) from a systems perspective, the location of wind-farms on the sub-transmission network, coupled with the variability inherent in their power output, can cause complex voltage control issues. The project has sought to develop a thorough understanding of the dynamic behaviour of type-3 WTGs, and in particular the WECC generic model. The behaviour of such models is governed by interactions between the continuous dynamics of state variables and discrete events associated with limits. It was shown that these interactions can be quite complex, and may lead to switching deadlock that prevents continuation of the trajectory. Switching hysteresis was proposed for eliminating deadlock situations. Various type-3 WTG models include control blocks that duplicate integrators. It was shown that this leads to non-uniqueness in the conditions governing steady-state, and may result in pre- and post-disturbance equilibria not coinciding. It also gives rise to a zero eigenvalue in the linearized WTG model. In order to eliminate the anomalous behaviour revealed through this investigation, WECC has now released a new generic model for type-3 WTGs. Wind-farms typically incorporate a variety of voltage control equipment including tapchanging transformers, switched capacitors, SVCs, STATCOMs and the WTGs themselves. The project has considered the coordinated control of this equipment, and has addressed a range of issues that arise in wind-farm operation. The #12;first concerns the ability of WTGs to meet reactive power requirements when voltage saturation in the collector network restricts the reactive power availability of individual generators. Secondly, dynamic interactions between voltage regulating devices have been investigated. It was found that under certain realistic conditions, tap-changing transformers may exhibit instability. In order to meet cost, maintenance, fault tolerance and other requirements, it is desirable for voltage control equipment to be treated as an integrated system rather than as independent devices. The resulting high-level scheduling of wind-farm reactive support has been investigated. In addressing this control problem, several forms of future information were considered, including exact future knowledge and stochastic predictions. Deterministic and Stochastic Dynamic Programming techniques were used in the development of control algorithms. The results demonstrated that while exact future knowledge is very useful, simple prediction methods yield little bene#12;fit. The integration of inherently variable wind generation into weak grids, particularly subtransmission networks that are characterized by low X=R ratios, aff#11;ects bus voltages, regulating devices and line flows. The meshed structure of these networks adds to the complexity, especially when wind generation is distributed across multiple nodes. A range of techniques have been considered for analyzing the impact of wind variability on weak grids. Sensitivity analysis, based on the power-flow Jacobian, was used to highlight sections of a system that are most severely a#11;ffected by wind-power variations. A continuation power flow was used to determine parameter changes that reduce the impact of wind-power variability. It was also used to explore interactions between multiple wind-farms. Furthermore, these tools have been used to examine the impact of wind injection on transformer tap operation in subtransmission networks. The results of a tap operation simulation study show that voltage regulation at wind injection nodes increases tap change operations. The tradeo#11;ff between local voltage regulation and tap change frequency is fundamentally important in optimizing the size of reactive compensation used for voltage regulation at wind injection nodes. Line congestion arising as a consequence of variable patterns of wind-power production has also been investigated. Two optimization problems have been formulated, based respectively on the DC and AC power flow models, for identifying vulnerable line segments. The DC optimization is computationally more e#14;fficient, whereas the AC sensitivity-based optimization provides greater accuracy.

  17. On the Configuration of the US Western Interconnection Voltage Stability Boundary

    SciTech Connect

    Makarov, Yuri V.; Vyakaranam, Bharat; Wu, Di; Hou, Zhangshuan; Elbert, Stephen T.; Huang, Zhenyu

    2014-04-01

    AbstractStability limits are considered in power system planning and operations to estimate the available stability margins and, if possible, to maximize the utilization of transmission facilities. These important tasks are influenced by configuration of the stability boundary. The paper introduces a new fast approach to explore the voltage stability boundary of a large system and reveal its detailed multidimensional structure. The 17939-bus U.S. Western Interconnection planning model was used to illustrate the method. Significant peculiarities of the boundarys configuration were identified, including its nonconvexity, discontinuity, branching and internal singularities (holes) that were not known before and could not been found by traditional methods. Experiments using WECC system are performed to evaluate the computation time using different methods. Our results show that the proposed methods are very promising in reducing calculation time and complexity

  18. Development of a terminal voltage stabilization system for the FOTIA at BARC

    NASA Astrophysics Data System (ADS)

    Kansara, M. J.; Sapna, P.; Subrahmanyam, N. B. V.; Bhatt, J. P.; Singh, P.

    2002-11-01

    A terminal voltage stabilization system for the folded tandem ion accelerator (FOTIA) was developed and is in continuous use. The system achieves good voltage stabilization, eliminates ground loops and noise interference. It incorporates a correcting circuit for compensating the mains frequency variations in the GVM amplifier circuit. The present system has two modes of operation namely GVM control mode and slit control mode. A voltage stability of about ±2 kV has been achieved. In this paper, some of the salient features of the voltage stabilization system are discussed.

  19. Global stability analysis method to numerically predict precursor of breakdown voltage

    NASA Astrophysics Data System (ADS)

    Shibata, Hisaichi; Ohmichi, Yuya; Watanabe, Yasumasa; Suzuki, Kojiro

    2015-10-01

    This study presents a new method for predicting a precursor of breakdown voltage. This method applies a global linear stability analysis to a drift-diffusion model coupled with the Poisson equation. The instability of the solution of these equations is evaluated with the proposed method and is considered to be the onset of a breakdown. The proposed method is validated in one dimension by using the Townsend theory as a reference. To extend the one-dimensional case and investigate the characteristics of multidimensional eigenmodes, we apply the method to two-dimensional plane-to-plane discharge tubes. To prove an adaptability against complex electrodes geometry, the discharge path and the corresponding breakdown voltage for the well-known corner-to-plane geometry are qualitatively evaluated.

  20. Ultrasonic evaluation of high voltage circuit boards

    NASA Technical Reports Server (NTRS)

    Klima, S. J.; Riley, T. J.

    1976-01-01

    Preliminary observations indicate that an ultrasonic scanning technique may be useful as a quick, low cost, nondestructive method for judging the quality of circuit board materials for high voltage applications. Corona inception voltage tests were conducted on fiberglass-epoxy and fiberglass-polyimide high pressure laminates from 20 to 140 C. The same materials were scanned ultrasonically by utilizing the single transducer, through-transmission technique with reflector plate, and recording variations in ultrasonic energy transmitted through the board thickness. A direct relationship was observed between ultrasonic transmission level and corona inception voltage. The ultrasonic technique was subsequently used to aid selection of high quality circuit boards for the Communications Technology Satellite.

  1. A Nonlinear Excitation Controller Design Method for Terminal Voltage Regulation and Transient Stability Enhancement

    NASA Astrophysics Data System (ADS)

    Huang, Chongxin; Zhang, Kaifeng; Dai, Xianzhong; Zang, Qiang

    2014-06-01

    This paper proposes a cascade control method to design a nonlinear excitation controller to guarantee the terminal voltage regulation and the transient stability. Firstly, a nonlinear automatic voltage regulator (NAVR) in the inner loop is designed to control the terminal voltage exactly. Secondly, the generator model including the NAVR is transformed to be a reduced one. Subsequently, based on the reduced generator model, the nonlinear power system stabilizer in the external loop is designed to enhance the transient stability of the power systems. Furthermore, a coordination strategy is presented to improve the performances of the terminal voltage regulation in the steady state and the stability in the transient state. Finally, the proposed method is verified by numerous simulation results.

  2. A new application area for fullerenes: voltage stabilizers for power cable insulation.

    PubMed

    Jarvid, Markus; Johansson, Anette; Kroon, Renee; Bjuggren, Jonas M; Wutzel, Harald; Englund, Villgot; Gubanski, Stanislaw; Andersson, Mats R; Mller, Christian

    2015-02-01

    Fullerenes are shown to be efficient voltage-stabilizers for polyethylene, i.e., additives that increase the dielectric strength of the insulation material. Such compounds are highly sought-after because their use in power-cable insulation may considerably enhance the transmission efficiency of tomorrow's power grids. On a molal basis, fullerenes are the most efficient voltage stabilizers reported to date. PMID:25504254

  3. Modeling of the effect of distributive generation on voltage stability on a large metropolitan district

    NASA Astrophysics Data System (ADS)

    Santos, Juan Santiago

    A theoretical foundation for modeling, analysis, and evaluation of large-scale application of distributive generation (DG) technologies connected to the bulk transmission grid is developed to answer questions concerning DG penetration levels as they affect system voltage. This work examines the penetration of DG on a dense metropolitan area by developing a non-specific distribution feeder model. There is significant detail to measure the effects of the feeder and DG penetration. The modeling approach replaces the existing aggregate load with an approximated model of the feeder, distribution transformers, and load in order to study the effects of these devices on voltage stability. To capture the effects of increased DG, a non-specific (not based on technologies) inverter device is modeled on the end of each feeder. This inverter model allows for depiction of commutation failure due to low voltage on the feeder to be captured, and is used to develop the effects of the distribution feeder from a bulk transmission perspective. A case study, using the methods developed in this research, demonstrated that a distributive generation penetration level of between 20% to 27% could be used to meet the electrical demands of a large metropolitan area. Following this level of DG penetration, the test system under single-outage conditions experienced rapid voltage decay similar to voltage collapse. Contributions of this research are predominately in the field of electrical engineering and are focused on numerical modeling of power systems. Major contributions include: (1) Data collection and modeling of DG exceeds any previous attempts, due to at least in part to the availability of data and to computer limitations. (2) Development of an aggregated Universal Distributed Generation Feeder (UDGF) model for the distribution system is a new approach. Previous studies examined single distribution feeders as opposed to modeling the entire distribution and transmission system together. (3) Numerical valuation methods utilized in this research have not been previously used in this manner and represent a novel approach. This research used the point at which the load-flow Jacobian is singular to represent an undesirable operating point where system voltages collapse. Groups interested in this research are bulk system planning engineers, power system operators, power system researchers, regulatory bodies and transmission system owners.

  4. Frequency stabilization of a GaAlAs semiconductor laser by voltage control

    NASA Astrophysics Data System (ADS)

    Ludvigsen, Hanne; Holmlund, Christer; Ikonen, Erkki; Junttila, Marja-Leena

    1992-06-01

    A frequency-stabilization method based on controlling the injection current and the voltage across the laser constant is presented. Frequency stability of 7 x 10 exp -8, and reproducibility of 3 x 10 exp -7, were obtained for a GaAlAs single-mode double heterostructure laser with a Fourier transform wavemeter.

  5. Stability Analysis of A.C. Voltage Controls for Shinkansen Feeding System with Multiple Power Converters

    NASA Astrophysics Data System (ADS)

    Kunomura, Ken; Koseki, Takafumi

    The recent introduction of very fast and frequent train services at Tokaido-Shinkansen makes it difficult to stabilize the feeding voltage only by compensating reactive power. Therefore, active power compensation has been introduced for further stabilization of the voltage, and a converter control strategy called fixed power factor method was applied in the commercial operation that started in February 2009. The feeding voltage stabilizing control by active power compensation is substantially more complicated than the conventional reactive power compensation. This paper describes a novel stability judging method for Shinkansen feeding system with multiple power converters; this method can be used to determine appropriate active/reactive compensation strategies that can be used by the operator of the new Shinkansen power supply system.

  6. Performance Comparison of Voltage Stability Indices for Weak Bus Identification in Power Systems

    NASA Astrophysics Data System (ADS)

    Verayiah, R.; Mohamed, A.; Shareef, H.; Zainal Abidin, I. Hj

    2013-06-01

    Voltage collapse event is identified as complex and localized in nature but its effect is extensive once occurred. The vital effect of voltage collapse would be the total system collapse or blackouts which would cost a large loss to utility companies. Eventually, on- line monitoring of power system stability has become an important factor for electric power utilities. The last utmost option to avert voltage collapse incident from occurring is by the implementation of under voltage load shedding scheme. The identification of location for load shedding is the main motivation of the study. The weakest bus in a power system is identified as the location for load shedding. This location is obtained using voltage stability index Ld. The performance and effectiveness of Ld index is compared with Fast Voltage Stability Index (FVSI) and Le Index. The results obtained indicate that Ld Index can be used to identify the weak bus in a power system and consequently for the placement of UVLS relays in a power system network.

  7. Stabilization of Gyrotron Frequency by PID Feedback Control on the Acceleration Voltage

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Tatematsu, Y.; Yamaguchi, Y.; Matsuki, Y.; Fujiwara, T.

    2015-12-01

    The results of frequency stabilization by proportional-integral-derivative (PID) feedback control of acceleration voltage in the 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) are presented. The experiment was organized on the basis of the frequency modulation by modulation of acceleration voltage of beam electrons. The frequency stabilization during 10 h experiment was better than 10-6, which is compared with the results of the frequency deviation in free-running gyrotron operation.

  8. Stability of highly nonlinear oxide-zinc resistors under continuous voltage of industrial frequency

    NASA Astrophysics Data System (ADS)

    Demyanenko, K. B.; Sergeyev, A. S.

    1985-01-01

    An experimental study of ZnO resistors for high-voltage overvoltage limiters without spark gaps was made, the purpose being to determine the dependence of their aging rate on the applied voltage and on the ambient temperature as well as on their initial current-voltage characteristic. Tests were performed on 150 strings of 10-15 resistors 28 mm in diameter each, connected in series and inserted in a thermosetting polyethylene tube. These strings were tested for a cumulative time of 115,000 hours with the ambient temperature varied from 0 C to 75 C and with the amplitude of the continuous voltage at 50 Hz frequency varied from 58% to 76% of the residual voltage. Accordingly, the aging process was found to have three stages: (1) initial transient buildup of aging rate; (2) power rising as linear function of time; and (3) power rising faster than resistor temperature, following loss of thermal balance and stability. An empirical relation for the aging rate is derived on this basis, including a voltage parameter which characterizes both current-voltage and power-voltage relations in the resistors.

  9. Automated Evaluation of Dynamic Performance of Impulse Voltage Measurement Systems

    NASA Astrophysics Data System (ADS)

    Faria, L. C.; Silva, E. C.; Silva, M. T.; Barbosa, C. R. H.; Azevedo, L. C.

    2015-01-01

    This manuscript presents and describes an automated system for the evaluation of the dynamic performance of high-voltage measurement systems, according to the requirements of the standard IEC 60060-2/2010. The system was developed in LabVIEW and controls the acquisition, measurement and analysis of step response tests of measurement systems, automatically calculating the relevant amplitude and time parameters.

  10. Enhancement of Voltage Stability of DC Smart Grid During Islanded Mode by Load Shedding Scheme

    NASA Astrophysics Data System (ADS)

    Nassor, Thabit Salim; Senjyu, Tomonobu; Yona, Atsushi

    2015-10-01

    This paper presents the voltage stability of a DC smart grid based on renewable energy resources during grid connected and isolated modes. During the islanded mode the load shedding, based on the state of charge of the battery and distribution line voltage, was proposed for voltage stability and reservation of critical load power. The analyzed power system comprises a wind turbine, a photovoltaic generator, storage battery as controllable load, DC loads, and power converters. A fuzzy logic control strategy was applied for power consumption control of controllable loads and the grid-connected dual active bridge series resonant converters. The proposed DC Smart Grid operation has been verified by simulation using MATLAB® and PLECS® Blockset. The obtained results show the effectiveness of the proposed method.

  11. Organic thin film devices with stabilized threshold voltage and mobility, and method for preparing the devices

    DOEpatents

    Nastasi, Michael Anthony; Wang, Yongqiang; Fraboni, Beatrice; Cosseddu, Piero; Bonfiglio, Annalisa

    2013-06-11

    Organic thin film devices that included an organic thin film subjected to a selected dose of a selected energy of ions exhibited a stabilized mobility (.mu.) and threshold voltage (VT), a decrease in contact resistance R.sub.C, and an extended operational lifetime that did not degrade after 2000 hours of operation in the air.

  12. Gyrotron Output Power Stabilization by PID Feedback Control of Heater Current and Anode Voltage

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Ueda, K.

    2014-12-01

    To provide stable output power of a gyrotron during long operation time the power stabilization was achieved by two schemes with PID feedback control of heater current and anode voltage. It was based on the dependence of the output power on both the anode voltage and the beam current and also on the dependence of the beam current on the gun heater current. Both schemes provided decrease of the power standard deviation to 0.3-0.5%. The comparison between parameters of both schemes is discussed in the paper.

  13. Improvement of stability of sinusoidally driven atmospheric pressure plasma jet using auxiliary bias voltage

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Kim, Jae Young; Kim, Jae Hyun; Kim, Dong Ha; Lee, Duck-Sik; Park, Choon-Sang; Park, Hyung Dal; Shin, Bhum Jae; Tae, Heung-Sik

    2015-12-01

    In this study, we have proposed the auxiliary bias pulse scheme to improve the stability of atmospheric pressure plasma jets driven by an AC sinusoidal waveform excitation source. The stability of discharges can be significantly improved by the compensation of irregular variation in memory voltage due to the effect of auxiliary bias pulse. From the parametric study, such as the width, voltage, and onset time of auxiliary bias pulse, it has been demonstrated that the auxiliary bias pulse plays a significant role in suppressing the irregular discharges caused by the irregular variation in memory voltage and stable discharge can be initiated with the termination of the auxiliary bias pulse. As a result of further investigating the effects of the auxiliary pulse scheme on the jet stability under various process conditions such as the distance between the jet head and the counter electrode, and carrier gas flow, the jet stability can be improved by adjusting the amplitude and number of the bias pulse depending on the variations in the process conditions.

  14. Surface and Structural Stabilities of Carbon Additives in High Voltage Lithium Ion Batteries

    SciTech Connect

    Zheng, Jianming; Xiao, Jie; Xu, Wu; Chen, Xilin; Gu, Meng; Li, Xiaohong S.; Zhang, Jiguang

    2012-11-23

    Several different carbons have been systematically investigated in high voltage lithium ion batteries. It was founded that the higher surface area, the more parasitic reactions initiating from different onset voltages. A closer inspection reveals that for the low surface area carbon such as Super P, PF6- ions intercalate into carbon structure above 4.7 V contributing partial capacity. For high surface area carbon, in addition to the electrolyte decomposition, the oxidation of functional groups at high voltage further increases the irreversible capacities and Li+ ion consumption. Coulombic efficiency, reversible capacity and cycling stability observed by using different carbon additives are successfully correlated with their structure and surface chemistry providing information for predictive selection of carbons in different energy storage systems.

  15. Development of real-time voltage stability monitoring tool for power system transmission network using Synchrophasor data

    NASA Astrophysics Data System (ADS)

    Pulok, Md Kamrul Hasan

    Intelligent and effective monitoring of power system stability in control centers is one of the key issues in smart grid technology to prevent unwanted power system blackouts. Voltage stability analysis is one of the most important requirements for control center operation in smart grid era. With the advent of Phasor Measurement Unit (PMU) or Synchrophasor technology, real time monitoring of voltage stability of power system is now a reality. This work utilizes real-time PMU data to derive a voltage stability index to monitor the voltage stability related contingency situation in power systems. The developed tool uses PMU data to calculate voltage stability index that indicates relative closeness of the instability by producing numerical indices. The IEEE 39 bus, New England power system was modeled and run on a Real-time Digital Simulator that stream PMU data over the Internet using IEEE C37.118 protocol. A Phasor data concentrator (PDC) is setup that receives streaming PMU data and stores them in Microsoft SQL database server. Then the developed voltage stability monitoring (VSM) tool retrieves phasor measurement data from SQL server, performs real-time state estimation of the whole network, calculate voltage stability index, perform real-time ranking of most vulnerable transmission lines, and finally shows all the results in a graphical user interface. All these actions are done in near real-time. Control centers can easily monitor the systems condition by using this tool and can take precautionary actions if needed.

  16. Chemical detection and laser wavelength stabilization employing spectroscopic absorption via laser compliance voltage sensing

    DOEpatents

    Taubman, Matthew S; Phillips, Mark C

    2014-03-18

    Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

  17. Using Controlled Shunt Reactors for Voltage Stabilization on the Example of Real Electric Power System

    NASA Astrophysics Data System (ADS)

    Gusev, A. S.; Suvorov, A. A.; Sulaymanov, A. O.

    2015-10-01

    The article is devoted to actual task of real-time simulation controlled shunt reactors to use in the appropriate electric power system. Such development allows fully and reliably reproducing the processes running in controlled shunt reactors and electric power systems as whole. As an example of such task solution the working results of controlled shunt reactors simulation and its application for voltage stabilization are presented.

  18. Energy functions, transient stability and voltage behaviour in power systems with nonlinear loads

    SciTech Connect

    Hiskens, I.A.; Hill, D.J. )

    1989-11-01

    This paper presents preliminary results in a program aimed at energy function analysis of transient behaviour of power systems with nonlinear loads. The model, which preserves the network structure, is of differential-algebraic type. This introduces some new analytical issues, but the concepts enable the establishment of a connection between transient (angle) stability, multiple stable equilibria and voltage behaviour. A practical method for determining and classifying equilibrium points of the model is developed.

  19. Evaluation of acoustic cavities for combustion stabilization.

    NASA Technical Reports Server (NTRS)

    Oberg, C. L.; Wong, T. L.; Ford, W. M.

    1972-01-01

    The stabilizing influence of acoustic cavities (quarterwave acoustic resonators) on acoustic modes of combustion instability has been studied. The ability to analytically predict cavity damping was improved. Relatively good agreement between predicted damping and measured stability was demonstrated. Full-scale motor firings were made to evaluate the influence of several parameters on stability. Results from these firings showed that stability was changed, but not dramatically, by changes in the engine operating conditions. Variations in the film-coolant flowrate do not significantly affect cavity stabilization. The ability to stabilize an engine with unconventional cavity configurations was demonstrated.

  20. Interpolation Approximation of Voltage Stability Constrained OPF (VSCOPF) for Reactive Power Planning

    SciTech Connect

    Tolbert, Leon M; Zhang, Wenjuan; Li, Fangxing

    2011-01-01

    Reactive power planning (RPP), or Var planning, is to identify the optimal size and location of reactive power sources. In this paper, first, the previous work using least square method to simplify the voltage stability constrained OPF (VSCOPF) model for RPP is presented. Then, this paper presents a new model simplification solution using interpolation. The interpolation approach can be easily applied to a piecewise formulation while preserving the continuity at boundary points, which cannot be easily achieved by previous works like the least square method. The proposed interpolation approach is numerically tested and compared with the least square approach. It is concluded that interpolation is an improved model simplification approach for RPP.

  1. Power system voltage stability and agent based distribution automation in smart grid

    NASA Astrophysics Data System (ADS)

    Nguyen, Cuong Phuc

    2011-12-01

    Our interconnected electric power system is presently facing many challenges that it was not originally designed and engineered to handle. The increased inter-area power transfers, aging infrastructure, and old technologies, have caused many problems including voltage instability, widespread blackouts, slow control response, among others. These problems have created an urgent need to transform the present electric power system to a highly stable, reliable, efficient, and self-healing electric power system of the future, which has been termed "smart grid". This dissertation begins with an investigation of voltage stability in bulk transmission networks. A new continuation power flow tool for studying the impacts of generator merit order based dispatch on inter-area transfer capability and static voltage stability is presented. The load demands are represented by lumped load models on the transmission system. While this representation is acceptable in traditional power system analysis, it may not be valid in the future smart grid where the distribution system will be integrated with intelligent and quick control capabilities to mitigate voltage problems before they propagate into the entire system. Therefore, before analyzing the operation of the whole smart grid, it is important to understand the distribution system first. The second part of this dissertation presents a new platform for studying and testing emerging technologies in advanced Distribution Automation (DA) within smart grids. Due to the key benefits over the traditional centralized approach, namely flexible deployment, scalability, and avoidance of single-point-of-failure, a new distributed approach is employed to design and develop all elements of the platform. A multi-agent system (MAS), which has the three key characteristics of autonomy, local view, and decentralization, is selected to implement the advanced DA functions. The intelligent agents utilize a communication network for cooperation and negotiation. Communication latency is modeled using a user-defined probability density function. Failure-tolerant communication strategies are developed for agent communications. Major elements of advanced DA are developed in a completely distributed way and successfully tested for several IEEE standard systems, including: Fault Detection, Location, Isolation, and Service Restoration (FLISR); Coordination of Distributed Energy Storage Systems (DES); Distributed Power Flow (DPF); Volt-VAR Control (VVC); and Loss Reduction (LR).

  2. Real Power and Reactive Power Control of a Three-Phase Single-Stage-PV System and PV voltage Stability

    SciTech Connect

    Li, Huijuan; Xu, Yan; Adhikari, Sarina; Rizy, D Tom; Li, Fangxing; Irminger, Philip

    2012-01-01

    Grid-connected photovoltaic (PV) systems with power electronic interfaces can provide both real and reactive power to meet power system needs with appropriate control algorithms. This paper presents the control algorithm design for a three-phase single-stage grid-connected PV inverter to achieve either maximum power point tracking (MPPT) or a certain amount of real power injection, as well as the voltage/var control. The switching between MPPT control mode and a certain amount of real power control mode is automatic and seamless. Without the DC-to-DC booster stage, PV DC voltage stability is an important issue in the control design especially when the PV inverter is operating at maximum power point (MPP) with voltage/var control. The PV DC voltage collapse phenomenon and its reason are discussed. The method based on dynamic correction of the PV inverter output is proposed to ensure PV DC voltage stability. Simulation results of the single-stage PV system during system disturbances and fast solar irradiation changes confirm that the proposed control algorithm for single-stage PV inverters can provide appropriate real and reactive power services and ensure PV DC voltage stability during dynamic system operation and atmospheric conditions.

  3. Two stability islands of quadrupole mass filter near q = 0.9 created by auxiliary radio frequency voltage.

    PubMed

    Luo, Chan; Jiang, Gongyu; Konenkov, Nikolai V; Ding, Chuanfan

    2009-01-01

    We report the numerical investigations of quadrupole mass filters concerning stability islands created by auxiliary radio frequency (RF) voltage with high and low frequencies near q = 0.9. The islands are located along the q axis near boundary value q = 0.908 with a low a parameter. The analysis is based upon the matrix method for stability diagram calculations and ion trajectory numerical simulation. The trajectory of ion motions is generated using Runge-Kutta-Nystrom-Dormand-Prince (RK-N-DP) order integration. The ion source model with Gaussian distribution of initial positions and transverse velocities is used. In RF-only operation mode, a resolution power of about R(0.1) = 600 without peak tails is achieved with a separation time of about 50 RF cycles. Relatively high resolution power of about 2000-3000 is observed in DC+RF separation mode with a low frequency auxiliary RF signal. The boundaries of stability diagram for additional RF voltage with high frequency are strongly diffused until the separation time is increased up to n = 300 RF cycles. The strong influence of phase shifts between main drive RF voltage and small auxiliary RF voltage on transmission is also examined. In DC + RF mode, the period of transmission varies with phase shift of pi or one period of the main drive RF voltage; and in RF-only mode this period is pi/2. PMID:19940333

  4. Evaluation of Conservation Voltage Reduction (CVR) on a National Level

    SciTech Connect

    Schneider, Kevin P.; Fuller, Jason C.; Tuffner, Francis K.; Singh, Ruchi

    2010-09-29

    Conservation Voltage Reduction (CVR) is a reduction of energy consumption resulting from a reduction of feeder voltage. While there have been numerous CVR systems deployed in North America there has been little substantive analytic analysis of the effect; the majority of the published results are based on empirical field measurements. Since these results are based on empirical measurements it is difficult to extrapolate how this technology will behave on the various types of distribution feeders found throughout the nation. This report has utilized the Taxonomy of Prototypical feeder developed under the Modern Grid Initiative (MGI), now the Modern Grid Strategy (MGS), in order to estimate the benefits of CVR on multiple distribution feeder types. This information will then be used to determine an estimate of the national benefits of a wide scale deployment of CVR.

  5. Genetic Algorithm Used for Load Shedding Based on Sensitivity to Enhance Voltage Stability

    NASA Astrophysics Data System (ADS)

    Titare, L. S.; Singh, P.; Arya, L. D.

    2014-12-01

    This paper presents an algorithm to calculate optimum load shedding with voltage stability consideration based on sensitivity of proximity indicator using genetic algorithm (GA). Schur's inequality based proximity indicator of load flow Jacobian has been selected, which indicates system state. Load flow Jacobian of the system is obtained using Continuation power flow method. If reactive power and active rescheduling are exhausted, load shedding is the last line of defense to maintain the operational security of the system. Load buses for load shedding have been selected on the basis of sensitivity of proximity indicator. The load bus having large sensitivity is selected for load shedding. Proposed algorithm predicts load bus rank and optimum load to be shed on load buses. The algorithm accounts inequality constraints not only in present operating conditions, but also for predicted next interval load (with load shedding). Developed algorithm has been implemented on IEEE 6-bus system. Results have been compared with those obtained using Teaching-Learning-Based Optimization (TLBO), particle swarm optimization (PSO) and its variant.

  6. Operational stability in pentacene thin-film transistors with threshold voltages tuned by oxygen plasma treatment

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshinari; Kitamura, Masatoshi; Kitani, Asahi; Arakawa, Yasuhiko

    2016-02-01

    Pentacene-based organic thin-film transistors (TFTs) having a SiO2 gate dielectric treated with oxygen plasma have been investigated for control of the threshold voltage. The threshold voltage changed in the wide range from ?15 to 80 V, depending on plasma treatment time, AC power for plasma generation, and gate dielectric thickness. The threshold voltage change was attributed to negative charges induced on and/or near the surface of the gate dielectric. The threshold voltage change on the order of 1 V was particularly proportional to plasma treatment time. The predictable change enables the control of threshold voltage in this range. In addition, the effect of gate bias stress on threshold voltage was examined. The results suggested that gate bias stress does not negate the threshold voltage change induced by plasma treatment.

  7. Wind Farm Stabilization by using DFIG with Current Controlled Voltage Source Converters Taking Grid Codes into Consideration

    NASA Astrophysics Data System (ADS)

    Okedu, Kenneth Eloghene; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji

    Recent wind farm grid codes require wind generators to ride through voltage sags, which means that normal power production should be re-initiated once the nominal grid voltage is recovered. However, fixed speed wind turbine generator system using induction generator (IG) has the stability problem similar to the step-out phenomenon of a synchronous generator. On the other hand, doubly fed induction generator (DFIG) can control its real and reactive powers independently while being operated in variable speed mode. This paper proposes a new control strategy using DFIGs for stabilizing a wind farm composed of DFIGs and IGs, without incorporating additional FACTS devices. A new current controlled voltage source converter (CC-VSC) scheme is proposed to control the converters of DFIG and the performance is verified by comparing the results with those of voltage controlled voltage source converter (VC-VSC) scheme. Another salient feature of this study is to reduce the number of proportionate integral (PI) controllers used in the rotor side converter without degrading dynamic and transient performances. Moreover, DC-link protection scheme during grid fault can be omitted in the proposed scheme which reduces overall cost of the system. Extensive simulation analyses by using PSCAD/EMTDC are carried out to clarify the effectiveness of the proposed CC-VSC based control scheme of DFIGs.

  8. HIGH VOLTAGE ENVIRONMENTAL APPLICATIONS, INC.ELECTRON BEAM TECHNOLOGY - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This report evaluates a high-voltage electron beam (E-beam) technology's ability to destroy volatile organic compounds (VOCs) and other contaminants present in liquid wastes. Specifically, this report discusses performance and economic data from a Superfund Innovative Technology...

  9. Diagnostic method for measuring plasma-induced voltages on the PBX-M (Princeton Beta Experiment-Modified) stabilizing shell

    SciTech Connect

    Kugel, H.W.; Okabayashi, M.; Schweitzer, S.

    1990-07-01

    The Princeton Beta Experiment-Modified (PBX-M) has a close-fitting conducting, passive plate, stabilizing shell which nearly surrounds highly indented, bean-shaped plasmas. The proximity of this electrically isolated shell to a large fraction of the plasma surface allows measurements similar to previous work on other tokamaks using floating probes and limiters. Measurements were performed to characterize the plasma-induced voltages on the PBX-M passive plate stabilizing shell during high-{beta} plasmas. Voltage differences were measured between the respective passive plate toroidal and poloidal gaps, the respective passive plates and the vessel, and an outer poloidal graphite limiter and its passive plate. The calibration and qualification testing procedures are discussed. The initial measurements found that the largest voltages were observed at plasma start-up and at the plasma current disruption and exhibited characteristics depending on operating conditions. The highest voltages observed have been at disruption and were less than 2 kV. 9 refs., 5 figs.

  10. Evaluation of developing inertial stabilization unit

    NASA Astrophysics Data System (ADS)

    Haruna, Masaki; Kodeki, Kazuhide; Shimizu, Seiichi; Fukushima, Kazuhiko; Takahara, Osamu; Ando, Toshiyuki; Suzuki, Jiro; Haraguchi, Eisuke

    2015-03-01

    Micro vibrations generated from some internal disturbance sources such as a reaction wheel degrades the pointing stability of an observation satellite. To suppress the pointing error, we have been developing an inertial stabilization unit. A prototype mechanism is designed based on concepts that it has non-contact actuators and sensors, and rotational leaf springs are applied to support a stabilized platform in order to meet two requirements which are precise drive and tolerance for launch load. Two kind of inertial sensors are installed on the platform to measure the attitude directly. Each of these two inertial sensors covers low or high bandwidth signal respectively. These signals will be able to be combined as one wideband signal to stabilize the platform in inertial space. In this paper, the developing prototype mechanism and control equipment are described and the basic evaluation results are reported. Less than 0.3urad as a drive precision and more than 100Hz as a local sensor control bandwidth are verified. The development of the system has not completely finished yet, but the basic performance is certified to meet the design specification. From now on, we continue to develop the unit. These future results can be applied to inter-satellite laser communication system.

  11. Evaluation of high temperature dielectric films for high voltage power electronic applications

    NASA Technical Reports Server (NTRS)

    Suthar, J. L.; Laghari, J. R.

    1992-01-01

    Three high temperature films, polyimide, Teflon perfluoroalkoxy and poly-P-xylene, were evaluated for possible use in high voltage power electronic applications, such as in high energy density capacitors, cables and microelectronic circuits. The dielectric properties, including permittivity and dielectric loss, were obtained in the frequency range of 50 Hz to 100 kHz at temperatures up to 200 C. The dielectric strengths at 60 Hz were determined as a function of temperature to 250 C. Confocal laser microscopy was performed to diagnose for voids and microimperfections within the film structure. The results obtained indicate that all films evaluated are capable of maintaining their high voltage properties, with minimal degradation, at temperatures up to 200 C. However, above 200 C, they lose some of their electrical properties. These films may therefore become viable candidates for high voltage power electronic applications at high temperatures.

  12. Evaluation of high temperature dielectric films for high voltage power electronic applications

    NASA Astrophysics Data System (ADS)

    Suthar, J. L.; Laghari, J. R.

    1992-06-01

    Three high temperature films, polyimide, Teflon perfluoroalkoxy and poly-P-xylene, were evaluated for possible use in high voltage power electronic applications, such as in high energy density capacitors, cables and microelectronic circuits. The dielectric properties, including permittivity and dielectric loss, were obtained in the frequency range of 50 Hz to 100 kHz at temperatures up to 200 C. The dielectric strengths at 60 Hz were determined as a function of temperature to 250 C. Confocal laser microscopy was performed to diagnose for voids and microimperfections within the film structure. The results obtained indicate that all films evaluated are capable of maintaining their high voltage properties, with minimal degradation, at temperatures up to 200 C. However, above 200 C, they lose some of their electrical properties. These films may therefore become viable candidates for high voltage power electronic applications at high temperatures.

  13. Enhancement of Transient Stability Limit and Voltage Regulation with Dynamic Loads Using Robust Excitation Control

    NASA Astrophysics Data System (ADS)

    Hossain, Jahangir; Mahmud, Apel; Roy, Naruttam K.; Pota, Hemanshu R.

    2013-10-01

    In stressed power systems with large induction machine component, there exist undamped electromechanical modes and unstable monotonic voltage modes. This article proposes a sequential design of an excitation controller and a power system stabiliser (PSS) to stabilise the system. The operating region, with induction machines in stressed power systems, is often not captured using a linearisation around an operating point, and to alleviate this situation a robust controller is designed which guarantees stable operation in a large region of operation. A minimax linear quadratic Gaussian design is used for the design of the supplementary control to automatic voltage regulators, and a classical PSS structure is used to damp electromechanical oscillations. The novelty of this work is in proposing a method to capture the unmodelled nonlinear dynamics as uncertainty in the design of the robust controller. Tight bounds on the uncertainty are obtained using this method which enables high-performance controllers. An IEEE benchmark test system has been used to demonstrate the performance of the designed controller.

  14. White OLED with high stability and low driving voltage based on a novel buffer layer MoOx

    NASA Astrophysics Data System (ADS)

    Jiang, Xue-Yin; Zhang, Zhi-Lin; Cao, Jin; Khan, M. A.; Khizar-ul-Haq; Zhu, Wen-Qing

    2007-09-01

    White organic light emitting diodes (WOLEDs) with copper phthalocyanine (CuPc), 4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine (m-MTDATA), tungsten oxide (WO3) and molybdenum oxide (MoOx) as buffer layers have been investigated. The MoOx based device shows superior performance with low driving voltage, high power efficiency and much longer lifetime than those with other buffer layers. For the Cell using MoOx as buffer layer and 4,7-diphenyl-1,10-phenanthroline (Bphen) as electron transporting layer (ETL), at the luminance of 1000 cd m-2, the driving voltage is 4.9 V, which is 4.2 V, 2 V and 0.7 V lower than that of the devices using CuPc (Cell-CuPc), m-MTDATA (Cell-m-MTDATA) and WO3 (Cell-WO3) as buffer layers, respectively. Its power efficiency is 7.67 Lm W-1, which is 2.37 times higher than that of Cell-CuPc and a little higher than that of Cell-m-MTDATA. The projected half-life under the initial luminance of 100 cd m-2 is 55 260 h, which is more than 4.6 times longer than that of Cell-m-MTDATA and Cell-CuPc. The superior performance of Cell-MoOx is attributed to its high hole injection ability and the stable interface between MoOx and organic material. The work function of MoOx has been measured by the contact potential difference method. The J-V curves of 'hole-only' devices indicate that a small hole injection barrier between MoOx/N,'-bis(naphthalene-1-y1)-N, N'-bis(phenyl)-benzidine (NPB) leads to a strong hole injection, resulting in a low driving voltage and a high stability.

  15. Stabilization of polymer electrolyte fuel cell voltage with reduced-order Lyapunov exponent feedback and corrective pressure perturbations

    NASA Astrophysics Data System (ADS)

    Burkholder, Michael B.; Litster, Shawn

    2015-02-01

    Polymer electrolyte fuel cell (PEFC) system efficiency can be decreased by instabilities resulting from the accumulation of water in the cathode as well as by excessive air delivery parasitic loads used to prevent liquid water accumulation. In this work, we present a new instability detection diagnostic tailored for the nonlinear and chaotic dynamics of PEFC operation with multi-phase flow in the gas channels. The instability statistic, the Lyapunov exponent of the reduced-order voltage return map, ?, is a measure of the exponential rate of divergence in the dynamic voltage signal measured from the fuel cell. A key advantage of this statistic for embedded control is that it is a self-referencing measure of the system stability for feedback and is not based on an a priori performance threshold. Our experiments demonstrate that the Lyapunov exponent statistic provides a warning typically 100 s in advance of significant power loss. Using this statistic as a control diagnostic, a new control scheme that detects PEFC instability in real time and mitigates it with pressure perturbations was applied experimentally to several fuel cell systems, including one that simulates stack operation. Our control scheme resulted in increased PEFC power, decreased cathode flooding leading to a lower parasitic load for air delivery, and stable PEFC performance.

  16. Contingency screening method for voltage stability analysis in the assessment of available transfer capability in deregulated power systems

    NASA Astrophysics Data System (ADS)

    Sundhararajan, Srinivasan

    2001-07-01

    The electric utility industry is going through the phase of restructuring towards evolving into a competitive market. In order to facilitate that transformation, the access to the transmission network is provided on a non discriminatory basis, which is limited only by the capability of the network to transfer power. Available Transfer Capability (ATC) has become the standard tool to compute the transfer capability remaining in the network over and above already committed use. The calculation of ATC involves network limitations due to thermal and voltage stability limits. Network limitations are to be calculated not only for the current operating condition but also for a worse case that could occur due to a set of contingency cases, which require huge amount of computation. This puts constraint on ATC to be an effective tool in real time operating environment. The aim of this dissertation is to study the computational efforts involved in the computation of ATC and propose a method to minimize the computation involved in the assessment of ATC due to the voltage stability limit. The proposed method performs ranking of the contingencies using a severity index based on the incremental reactive power losses between the base case and the contingency case. Based on the ranking, a short list of contingencies is to be selected for full simulation. Since the impact of the contingencies is not known until the power flow equations are solved, the convergence of the contingency cases is not known a priori. For the purpose of identifying the base case load level for contingency screening, couple of measures of convergence of contingency cases at each load level on the base case curve are proposed, one for large correction errors and the other for divergence behavior due to load increase. The proposed method is validated with simulations on practical large power systems.

  17. Evaluation of Niobium as Candidate Electrode Material for DC High Voltage Photoelectron Guns

    NASA Technical Reports Server (NTRS)

    BastaniNejad, M.; Mohamed, Abdullah; Elmustafa, A. A.; Adderley, P.; Clark, J.; Covert, S.; Hansknecht, J.; Hernandez-Garcia, C.; Poelker, M.; Mammei, R.; Surles-Law, K.; Williams, P.

    2012-01-01

    The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirror-like finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain, and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and field strength. In all cases, field emission from electrodes (stainless steel and/or niobium) could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode was biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (< 10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18:7 MV/m.

  18. Lidocaine stabilizes the open state of CNS voltage-dependent sodium channels.

    PubMed

    Castaeda-Castellanos, David R; Nikonorov, Igor; Kallen, Roland G; Recio-Pinto, E

    2002-03-28

    We have previously reported that the lidocaine action is different between CNS and muscle batrachotoxin-modified Na+ channels [Salazar et al., J. Gen. Physiol. 107 (1996) 743-754; Brain Res. 699 (1995) 305-314]. In this study we examined lidocaine action on CNS Na+ currents, to investigate the mechanism of lidocaine action on this channel isoform and to compare it with that proposed for muscle Na+ currents. Na+ currents were measured with the whole cell voltage clamp configuration in stably transfected cells expressing the brain alpha-subunit (type IIA) by itself (alpha-brain) or together with the brain beta(1)-subunit (alphabeta(1)-brain), or the cardiac alpha-subunit (hH1) (alpha-cardiac). Lidocaine (100 microM) produced comparable levels of Na+ current block at positive potentials and of hyperpolarizing shift of the steady-state inactivation curve in alpha-brain and alphabeta(1)-brain Na+ currents. Lidocaine accelerated the rates of activation and inactivation, produced an hyperpolarizing shift in the steady-state activation curve and increased the current magnitude at negative potentials in alpha-brain but not in alphabeta(1)-brain Na+ currents. The lidocaine action in alphabeta(1)-brain resembled that observed in alpha-cardiac Na+ currents. The lidocaine-induced increase in current magnitude at negative potentials and the hyperpolarizing shift in the steady-state activation curve of alpha-brain, are novel effects and suggest that lidocaine treatment does not always lead to current reduction/block when it interacts with Na+ channels. The data are explained by using a modified version of the model proposed by Vedantham and Cannon [J. Gen. Physiol., 113 (1999) 7-16] in which we postulate that the difference in lidocaine action between alpha-brain and alphabeta(1)-brain Na+ currents could be explained by differences in the lidocaine action on the open channel state. PMID:11978401

  19. Evaluation of the piezoelectric properties and voltage generation of flexible zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Laurenti, M.; Stassi, S.; Lorenzoni, M.; Fontana, M.; Canavese, G.; Cauda, V.; Pirri, C. F.

    2015-05-01

    Local piezoresponse and piezoelectric output voltage were evaluated on ZnO thin films deposited by radio-frequency magnetron sputtering on hard Si/Ti/Au and flexible Cu-coated polyimide substrates. Three different thicknesses of ZnO films were studied (285 nm, 710 nm, and 1380 nm), focusing on characteristics like crystallinity, grain size, surface roughness, and morphology. Independent of the nature of the metal layer and the substrate, our results show that thicker films presented a higher level of crystallinity and a preferential orientation along the c-axis direction, as well as a lower density of grain boundaries and larger crystal sizes. The improvement of the crystalline structure of the material directly enhances its piezoelectric properties, as confirmed by the local characterizations performed by piezoresponse force microscopy and by the evaluation of the output voltage generation under the application of a periodical mechanical deformation on the whole film. In particular, the highest value of the d33 coefficient obtained (8 pm V-1) and the highest generated output voltage (0.746 V) belong to the thickest films on hard and flexible substrates, respectively. These results envision the use of ZnO thin films—particularly on flexible substrates—as conformable, reliable, and efficient active materials for use in nanosensing, actuation, and piezoelectric nanogenerators.

  20. Evaluating the Field Emission Characteristics of Aluminum for DC High Voltage Photo-Electron Guns

    NASA Astrophysics Data System (ADS)

    Taus, Rhys; Poelker, Matthew; Forman, Eric; Mamun, Abdullah

    2013-10-01

    High current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces electron beam. Most of the laser light (~ 65%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. This work evaluates the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity: aluminum and copper. These electrodes could serve as effective heat sinks, to passively cool the photocathode that resides within such a structure. However, literature suggests ``soft'' materials like aluminum and copper are ill suited for photogun applications, due to excessive field emission when biased at high voltage. This work provides an evaluation of aluminum and copper electrodes inside a high voltage field emission test stand, before and after coating with titanium nitride (TiN), a coating that enhances surface hardness. National Science Foundation Award Number: 1062320 and the Department of Defence ASSURE program.

  1. Evaluating the Field Emission Characteristics of Aluminum for DC High Voltage Photo-Electron Guns

    NASA Astrophysics Data System (ADS)

    Taus, Rhys; Poelker, Matthew; Forman, Eric; Mamun, Abdullah

    2014-03-01

    High current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces electron beam. Most of the laser light (~ 65%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. This work evaluates the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity: aluminum and copper. These electrodes could serve as effective heat sinks, to passively cool the photocathode that resides within such a structure. However, literature suggests ``soft'' materials like aluminum and copper are ill suited for photogun applications, due to excessive field emission when biased at high voltage. This work provides an evaluation of aluminum and copper electrodes inside a high voltage field emission test stand, before and after coating with titanium nitride (TiN), a coating that enhances surface hardness. National Science Foundation Award Number: 1062320 and the Department of Defence ASSURE program.

  2. Quantitative Evaluation of Lightning Surge Range Voltage-time Characteristics in High Pressure SF6 Gas

    NASA Astrophysics Data System (ADS)

    Shinkai, Hiroyuki; Goshima, Hisashi; Yashima, Masafumi; Fujinami, Hideo

    Since gas-insulated switchgear (GIS) is subjected to very fast transient overvoltages such as lightning surges or disconnector switching surges. Therefore the sparkover voltage and time (V-t) characteristics of SF6 in a very short time range of less than 1?s are of great interest from the viewpoint of insulation design and coordination for a GIS. This paper describes the V-t characteristics of SF6 at a gas pressure of 0.5MPa using a steep-front square impulse voltage under a quasi-uniform field gap and presents a quantitative evaluation of the V-t characteristics for a nonstandard lightning impulse voltage. In the case of a square impulse, the V-t characteristics of positive polarity were observed to be almost flat over a long time range from 80ns to 10?s, and rose steeply over a short time range from 80ns down to 20ns. For negative polarity, the V-t characteristics exhibit a gentle rise from 200ns down to 40ns. In the estimation of V-t characteristics, the equal-area criterion parameters were quantitatively estimated using the square impulse. For a nonstandard lightning impulse, we found that the application of equal area criterion with these parameters for the non-oscillating impulse and oscillating impulse of up to 5.3MHz as a model of lightning surge and disconnector switching surge is possible.

  3. Evaluation of the Threshold of Stability for the Human Spine

    PubMed Central

    Tanaka, Martin L.; Nussbaum, Maury A.; Ross, Shane D.

    2009-01-01

    0. Abstract The threshold of stability (ToS) is introduced as a new tool for evaluating spinal stability. Current methods have evaluated the magnitude of spinal kinematic variability, stability diffusion, or Lyapunov exponents. This present method differs by modifying task difficulty to obtain a critical value delineating regions of stability and instability. Conceptually, as task difficulty increases, kinematic variability of the system increases and the basin of stability decreases. When kinematic variability exceeds the basin of stability, stability cannot be maintained over time. This concept is first illustrated using a mathematical model, from which an effective potential function was calculated to show the relationships among kinematic variability, the basin of stability, and task difficulty. In addition, an experiment was performed to evaluate the sensitivity of the ToS to changes in postural control using visual feedback as a control variable. The ToS was found to be more sensitive than the Lyapunov exponent to removal of visual feedback, suggesting it may have use as a diagnostic indicator (e.g. for low back pain). Furthermore, this new method has an additional advantage in that minimal instrumentation is needed. Its simplicity, sensitivity, and low cost suggest that the ToS has potential as a diagnostic or prognostic tool in a clinical setting. PMID:19345355

  4. Methods for determining optical power, for power-normalizing laser measurements, and for stabilizing power of lasers via compliance voltage sensing

    SciTech Connect

    Taubman, Matthew S; Phillips, Mark C

    2015-04-07

    A method is disclosed for power normalization of spectroscopic signatures obtained from laser based chemical sensors that employs the compliance voltage across a quantum cascade laser device within an external cavity laser. The method obviates the need for a dedicated optical detector used specifically for power normalization purposes. A method is also disclosed that employs the compliance voltage developed across the laser device within an external cavity semiconductor laser to power-stabilize the laser mode of the semiconductor laser by adjusting drive current to the laser such that the output optical power from the external cavity semiconductor laser remains constant.

  5. Reliability and Power Quality Evaluation of High-Voltage Supplied Customer

    NASA Astrophysics Data System (ADS)

    Yoshino, Jun; Kita, Hiroyuki; Tanaka, Eiichi; Hasegawa, Jun; Kubo, Hiroshi; Yonaga, Shigeru

    Recently, a number of electric consumers have concerned about the reliability of electricity to be served. For example, some consumers need the electricity with a higher reliability by the automation of manufacturing processes. On the other hand, some consumers need the electricity of a cheaper price even if the reliability becomes a little worse. Under such circumstances, it is necessary that power suppliers evaluate the needs of every consumers precisely and propose the most desirable measures for meeting their requirements. This paper develops a tool to analyze the reliability for high-voltage supplied consumers quantitatively. Further, this paper presents a method for evaluating the outage cost of consumers to help them choose the most appropriate measures for maintaining the reliability. The proposed method applies the fuzzy reasoning approach. The validity of the proposed method is ascertained through some numerical simulations.

  6. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

    DOE PAGESBeta

    BastaniNejad, Mahzad; Elmustafa, Abdelmageed A.; Forman, Eric; Covert, Steven; Hansknecht, John; Hernandez-Garcia, Carlos; Poelker, Matthew; Das, Lopa; Kelley, Michael; Williams, Phillip

    2015-07-01

    DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (~nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>μA) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolishedmore » by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.« less

  7. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

    SciTech Connect

    BastaniNejad, Mahzad; Elmustafa, Abdelmageed A.; Forman, Eric; Covert, Steven; Hansknecht, John; Hernandez-Garcia, Carlos; Poelker, Matthew; Das, Lopa; Kelley, Michael; Williams, Phillip

    2015-07-01

    DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (~nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>μA) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolished by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.

  8. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

    SciTech Connect

    BastaniNejad, Mahzad Elmustafa, Abdelmageed A.; Forman, Eric; Covert, Steven; Hansknecht, John; Hernandez-Garcia, Carlos; Poelker, Matthew; Das, Lopa; Kelley, Michael; Williams, Phillip

    2015-07-15

    DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (∼nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>μA) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolished by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The authors speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.

  9. Evaluation of higher distribution and/or utilization voltages. First interim report (December 1978): literature search and problem definition

    SciTech Connect

    Not Available

    1981-04-01

    A literature search has been conducted on the economics and technical problems associated with the use of higher voltages in both the primary distribution and secondary utilization systems. After a literature review and evaluation, an assessment of the state-of-the-art with regard to high voltage has been made and is presented for the primary and secondary distribution systems, end use elements, and economics and system analysis or optimization. An annotated bibliography is provided for each of the three categories. A comprehensive list of potential advantages and disadvantages of higher primary distribution and utilization voltages has also been prepared and is presented.

  10. ENVIRONMENTAL EVALUATION FOR UTILIZATION OF ASH IN SOIL STABILIZATION

    SciTech Connect

    David J. Hassett; Loreal V. Heebink

    2001-08-01

    The Minnesota Pollution Control Agency (MPCA) approved the use of coal ash in soil stabilization, indicating that environmental data needed to be generated. The overall project goal is to evaluate the potential for release of constituents into the environment from ash used in soil stabilization projects. Supporting objectives are: (1) To ensure sample integrity through implementation of a sample collection, preservation, and storage protocol to avoid analyte concentration or loss. (2) To evaluate the potential of each component (ash, soil, water) of the stabilized soil to contribute to environmental release of analytes of interest. (3) To use laboratory leaching methods to evaluate the potential for release of constituents to the environment. (4) To facilitate collection of and to evaluate samples from a field runoff demonstration effort. The results of this study indicated limited mobility of the coal combustion fly ash constituents in laboratory tests and the field runoff samples. The results presented support previous work showing little to negligible impact on water quality. This and past work indicates that soil stabilization is an environmentally beneficial CCB utilization application as encouraged by the U.S. Environmental Protection Agency. This project addressed the regulatory-driven environmental aspect of fly ash use for soil stabilization, but the demonstrated engineering performance and economic advantages also indicate that the use of CCBs in soil stabilization can and should become an accepted engineering option.

  11. Evaluation of stability of live attenuated camelpox vaccine stabilized with different stabilizers and reconstituted with various diluents.

    PubMed

    Prabhu, M; Bhanuprakash, V; Venkatesan, G; Yogisharadhya, R; Bora, D P; Balamurugan, V

    2014-05-01

    In this study, thermostability of a Vero cell attenuated live camelpox vaccine under conventional lyophilization conditions has been evaluated. Three stabilizers were used separately for freeze-drying the vaccine and the stability of the vaccine, both in freeze-dried and reconstituted forms at different temperatures was assessed. The study revealed that the camelpox vaccine lyophilized with TAA stabilizer found superior with a shelf life of 44 months, 227 days, 22 days and 20 days at 4, 25, 37 and 45C, respectively followed by LS stabilizer. In terms of half-life, TAA stabilizer proved better followed by LS and BUGS stabilizers at all temperatures except at 25C in which LS found relatively superior. Among the four diluents viz. 1x PBS (phosphate buffered saline, pH 7.4), 0.85% NaCl, distilled water and 1M MgSO4, PBS was a better diluent followed by 0.85% NaCl. Both the diluents maintained the infectivity titer more than the minimum effective dose (3 log10TCID50 with a maximum titre of 6.53 log10TCID50 in both the diluents) for 60h at 37 and 45C. However, 1M MgSO4 found less suitable for camelpox vaccine dilution. The study indicates that the TAA and 1 PBS are the choice of stabilizer and diluent, respectively for camelpox vaccine. PMID:24657207

  12. Intrinsic Surface Stability in LiMn2-xNix04-s (x = 0.45, 0.5) High Voltage Spinel Materials for Lithium Ion Batteries

    SciTech Connect

    Carroll, Kyler J.; Yang, Ming-Che; Veith, G. M.; Dudney, N. J.; Meng, Ying Shirley

    2012-01-01

    This work reports the surface stability of the high voltage Li ion cathode LiMn{sub 2x}Ni{sub x}O{sub 4?} (x = 0.5, 0.45) by comparing thin film and powder composite electrodes after cycling using X-ray photoelectron spectroscopy. The thin film electrodes offer the ability to probe the surface of the material without the need of a conductive agent and polymer binder typically used in composite electrodes. The results suggest that neither oxidation of PF{sub 6} to POF{sub 3} nor the decomposition of ethylene carbonate or dimethylene carbonate occurs on the surface of the spinel material. These results confirm the enhanced cycling stability and rate capability associated with the high voltage spinel material and suggests that the SEI layer forms due to the reaction of electrochemically inactive components in composite electrodes with the electrolyte.

  13. Abandoned metal mine stability risk evaluation.

    PubMed

    Bétournay, Marc C

    2009-10-01

    The abandoned mine legacy is critical in many countries around the world, where mine cave-ins and surface subsidence disruptions are perpetual risks that can affect the population, infrastructure, historical legacies, land use, and the environment. This article establishes abandoned metal mine failure risk evaluation approaches and quantification techniques based on the Canadian mining experience. These utilize clear geomechanics considerations such as failure mechanisms, which are dependent on well-defined rock mass parameters. Quantified risk is computed using probability of failure (probabilistics using limit-equilibrium factors of safety or applicable numerical modeling factor of safety quantifications) times a consequence impact value. Semi-quantified risk can be based on failure-case-study-based empirical data used in calculating probability of failure, and personal experience can provide qualified hazard and impact consequence assessments. The article provides outlines for land use and selection of remediation measures based on risk. PMID:19645755

  14. Evaluation of a 125I-labelled benzazepinone derived voltage-gated sodium channel blocker for imaging with SPECT.

    PubMed

    Prez-Medina, Carlos; Patel, Niral; Robson, Mathew; Badar, Adam; Lythgoe, Mark F; rstad, Erik

    2012-12-21

    Voltage-gated sodium channels (VGSCs) are a family of transmembrane proteins that mediate fast neurotransmission, and are integral to sustain physiological conditions and higher cognitive functions. Imaging of VGSCs in vivo holds promise as a tool to elucidate operational functions in the brain and to aid the treatment of a wide range of neurological diseases. To assess the suitability of 1-benzazepin-2-one derived VGSC blockers for imaging, we have prepared a (125)I-labelled analogue of BNZA and evaluated the tracer in vivo. In an automated patch-clamp assay, a diastereomeric mixture of the non-radioactive compound blocked the Na(v)1.2 and Na(v)1.7 VGSC isoforms with IC(50) values of 4.1 1.5 ?M and 0.25 0.07 ?M, respectively. [(3)H]BTX displacement studies revealed a three-fold difference in affinity between the two diastereomers. Iodo-destannylation of a tin precursor with iodine-125 afforded the two diastereomerically pure tracers, which were used to assess binding to VGSCs in vivo by comparing their tissue distributions in mice. Whilst the results point to a lack of VGSC binding in vivo, SPECT imaging revealed highly localized uptake in the interscapular region, an area typically associated with brown adipose tissue, which in addition to high metabolic stability of the iodinated tracer, demonstrate the potential of 1-benzazepin-2-ones for in vivo imaging. PMID:23117159

  15. Experimental evaluation of a positive-voltage-driven unimorph deformable mirror for astronomical applications

    NASA Astrophysics Data System (ADS)

    Chen, Junjie; Ma, Jianqiang; Mao, Yuxin; Liu, Ying; Li, Baoqing; Chu, Jiaru

    2015-11-01

    A modified low-cost unimorph deformable mirror (DM) driven only by positive voltages for atmospheric turbulence compensation is presented. The 214 patterned inner actuators generate convex deformations for aberration correction, while one outer ring actuator generates an overall concave bias. To evaluate the aberration correction capability of the proposed DM, the iterative reconstruction of Zernike aberrations and correction were performed in an adaptive optics test system. The experimental results indicate that the fabricated DM has an excellent aberration correction capability, particularly matching the first 20 term Zernike aberrations with the normalized residual root-mean-square (RMS) error <5%. Furthermore, the random atmospheric turbulence aberrations were simulated based on Karhunen-Love coefficients and reconstructed using the fabricated DM. The simulative and experimental results show that the atmospheric turbulence aberrations can be steadily compensated with ?/40 (?=2.2 ?m) RMS residual error, indicating the prospect for atmospheric applications.

  16. Stability evaluation and improvement of adaptive optics systems by using the Lyapunov stability approach

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Chen, Tao; Liu, Xin-yue; Lin, Xu-dong; Yang, Xiao-xia; Li, Hong-zhuang

    2016-02-01

    In this research, investigations on the closed-loop control stability of adaptive optics systems are conducted by using the Lyapunov approach. As an direct metric of the control stability, the error propagator includes the effects of both the integral gain and the influence matrix and is effective for control-stability evaluation. An experimental 97-element AO system is developed for the control-stability investigation, and the Southwell sensor-actuator configuration rather than the Fried geometry is adopted so as to suppress the potential waffle mode. Because filtering out small singular values of the influence matrix can be used to improve the control stability, the effect of the influence matrix and the effect of the integral gain are considered as a whole by using the error propagator. Then, the control stability of the AO system is evaluated for varying the integral gains and the number of filtered-out singular values. Afterwards, an analysis of the evaluations of the error propagator is made, and a conclusion can be drawn that the control stability can be improved by filtering out more singular values of the influence matrix when the integral gain is high. In other words, the error propagator is useful for trading off the bandwidth error and the fitting error of AO systems in a control-stability approach. Finally, a performance measurement of the experimental AO system is conducted when 13 smaller singular values of the influence matrix are filtered out, and the results show that filtering out a small fraction of the singular values has a minor influence on the performance of this AO system.

  17. Age-Related Differences in Evaluating Developmental Stability

    ERIC Educational Resources Information Center

    Mustafic, Maida; Freund, Alexandra M.

    2013-01-01

    Two studies examined the hypothesis that the evaluation of developmental stability changes across adulthood. Results of Study 1 ("N" = 119) supported the expectation that older adults ("M"[subscript age] = 65.29 years)--compared to younger ("M"[subscript age] = 23.38 years) and middle-aged adults

  18. Hazards evaluation of plutonium metal opening and stabilization

    SciTech Connect

    JOHNSON, L.E.

    1999-08-31

    Hazards evaluation is the analysis of the significance of hazardous situations associated with an activity OK process. The HE used qualitative techniques of Hazard and Operability (HazOp) analysis and What-If analysis to identify those elements of handling and thermal stabilization processing that could lead to accidents.

  19. Evaluation Methods of Contamination Flashover Voltage Performance of Cylindrical Type Semi-conducting Glaze Porcelain Insulators

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuma; Hayashi, Akio; Saka, Chiharu; Sakanishi, Kenji; Matsuoka, Ryosuke; Ito, Susumu; Fujii, Osamu

    Higher contamination flashover voltage of a semi-conducting glaze (SG) insulator owes primarily to the drying effect by leakage current flowing in the glaze. Significant reduction in contamination flashover voltage was confirmed on a cylindrical SG insulator when fog density was increased from 0.5g/m3 to 13g/m3 in clean fog test. The effect of de-energized duration between trip-out and re-energization on the contamination flashover voltage of a cylindrical SG insulator under cold-wet switch-on conditions was investigated. As the de-energized duration becomes shorter, the flashover voltage of a cylindrical SG insulator becomes higher. Higher contamination design voltages may be adopted even under cold-wet switch-on conditions.

  20. Stability evaluation of the Markel Mine at Weeks Island, Louisiana

    SciTech Connect

    Hoffman, E.L.

    1994-06-01

    A three dimensional (3D) finite element analysis of the Markel Mine located on Weeks Island was performed to: (1) evaluate the stability of the mine and (2) determine the effect of mine failure on the nearby Morton Salt mine and SPR facilities. The first part of the stability evaluation investigates the effect of pillar failure on mine stability. These simulations revealed that tensile stresses and dilatant damage develop in the overlying salt as a result of pillar loss. These tensile stresses extend to the salt/overburden interface only for the case where all 45 of the pillars are assumed to fail. Tensile stresses would likely cause microfracturing of the salt, resulting in a flow path for groundwater from the overlying aquifer to enter the mine. The dilatant damage bridges between the mine and the overburden in the case where 15 or more pillars are removed from the model. Dilatant damage is attributed to microfracturing or changes in the pore structure of the salt and could also result in a flow path for groundwater to enter the mine. The second part of the Markel Mine evaluation investigates the stability of the pillars with respect to three failure mechanisms: tensile failure, compressive failure, and creep rupture. A 3D slabbing pillar model of the Markel mine was developed to investigate progressive failure of the pillars and the effect of slabbing on mine stability. Based on a strain-limiting creep rupture criterion, pillar failure is predicted to be extensive at present. The associated loss of pillar strength should be equivalent to removing all pillars from the model as was done in the first part of this stability analysis, resulting in the possibility of ground water intrusion. Since creep rupture is not a well understood phenomenon, further development and validation of this criterion is recommended.

  1. Evaluating the Performance of a Battery Using Temperature and Voltage Profiles and a Battery-Resistor Circuit Module

    ERIC Educational Resources Information Center

    Sawyer, Bryan; Ji, Michelle; Gordon, Michael J.; Suppes, Galen J.

    2010-01-01

    An experimental learning module has been developed to study the mass and energy balance involved with operation of an AA Alkaline battery under a load current. An extension of the module allows evaluation of laboratory-assembled batteries using granular anodic/cathodic materials. The system allows load resistance to be varied and measures voltage

  2. High voltage stability of LiCoO2 particles with a nano-scale Lipon coating

    SciTech Connect

    Kim, Yoongu; Veith, Gabriel M; Nanda, Jagjit; Unocic, Raymond R; Dudney, Nancy J

    2011-01-01

    For high-voltage cycling of rechargeable Li batteries, a nano-scale amorphous Li-ion conductor, lithium phosphorus oxynitride (Lipon), has been coated on surfaces of LiCoO{sub 2} particles by combining a RF-magnetron sputtering technique and mechanical agitation of LiCoO{sub 2} powders. LiCoO{sub 2} particles coated with 0.36 wt% ({approx}1 nm thick) of the amorphous Lipon, retain 90% of their original capacity compared to non-coated cathode materials that retain only 65% of their original capacity after more than 40 cycles in the 3.0-4.4 V range with a standard carbonate electrolyte. The reason for the better high-voltage cycling behavior is attributed to reduction in the side reactions that cause increase of the cell resistance during cycling. Further, Lipon coated particles are not damaged, whereas uncoated particles are badly cracked after cycling. Extending the charge of Lipon-coated LiCoO{sub 2} to higher voltage enhances the specific capacity, but more importantly the Lipon-coated material is also more stable and tolerant of high voltage excursions. A drawback of Lipon coating, particularly as thicker films are applied to cathode powders, is the increased electronic resistance that reduces the power performance.

  3. Evaluating capacitor-switching devices for preventing nuisance tripping of adjustable-speed drives due to voltage magnification

    SciTech Connect

    Bellei, T.A.; O`Leary, R.P.; Camm, E.H.

    1996-07-01

    Nuisance overvoltage tripping of pulse-width modulated adjustable-speed drives, due to switching of shunt capacitor banks at a utility`s substation and the subsequent voltage magnification which can occur at an industrial customer`s utilization-voltage bus, is discussed. Adjustable-speed drive design considerations affecting transient overvoltage ride-through capability are identified and discussed. A comparative evaluation of three switching devices equipped with transient overvoltage control, namely, circuit breakers with pre-insertion resistors, circuit switchers with highly damped pre-insertion inductors, and controlled closing devices, is presented.

  4. Evaluation of slope stability with respect to snowpack spatial variability

    NASA Astrophysics Data System (ADS)

    Gaume, J.; Schweizer, J.; Herwijnen, A.; Chambon, G.; Reuter, B.; Eckert, N.; Naaim, M.

    2014-09-01

    The evaluation of avalanche release conditions constitutes a great challenge for risk assessment in mountainous areas. The spatial variability of snowpack properties has an important impact on snow slope stability and thus on avalanche formation, since it strongly influences failure initiation and crack propagation in weak snow layers. Hence, the determination of the link between these spatial variations and slope stability is very important, in particular, for avalanche public forecasting. In this study, a statistical-mechanical model of the slab-weak layer (WL) system relying on stochastic finite element simulations is used to investigate snowpack stability and avalanche release probability for spontaneously releasing avalanches. This model accounts, in particular, for the spatial variations of WL shear strength and stress redistribution by elasticity of the slab. We show how avalanche release probability can be computed from release depth distributions, which allows us to study the influence of WL spatial variations and slab properties on slope stability. The importance of smoothing effects by slab elasticity is verified and the crucial impact of spatial variation characteristics on the so-called knock-down effect on slope stability is revisited using this model. Finally, critical length values are computed from the simulations as a function of the various model parameters and are compared to field data obtained with propagation saw tests.

  5. Evaluation of frequency stability in double optical feedback ECDL systems

    NASA Astrophysics Data System (ADS)

    Doi, Kohei; Kobayashi, Yumie; Maehara, Shinya; Sato, Takashi; Maruyama, Takeo; Ohkawa, Masashi; Tsubokawa, Tsuneya

    2006-02-01

    External cavity diode laser (ECDL) systems are presently experiencing a surge in popularity as laser light-sources, in advanced optical communications- and measurement-applications. Because such systems require that their external reflectors be precisely controlled to eliminate low frequency fluctuations (LFF) in optical output, we conducted experiments with a two-cavity version of ECDL system, which was expected to eliminate LFF easily. This technique brings the added advantages of a narrower linewidth than would be achievable via a single optical feedback. However, the ECDL's oscillation frequency is susceptible to the influences of the driving current, changes in the refractive index, and the expansion/contraction of the length of the external reflector that results from fluctuations in atmospheric temperature. We made every effort to maintain the length of the ECDL cavity, while evaluating oscillation-frequency stability. We used a super-inver board as the platform for our ECDL system, in order to minimize the influence of thermal expansion. Moreover, our ECDL system combines an Rb cell within an external cavity to improve stability; by restricting the LD frequency to both the external cavity mode and to the Rb saturated absorption spectrum. We used the square root of the Allan variance to evaluate oscillation frequency stability, observing, in the process, that it improved stability about one order of magnitude.

  6. Stability evaluation of Styrylpyrone derivative (SPD) incorporated products

    NASA Astrophysics Data System (ADS)

    Bahtiar, Adibah Ahamad; Nor, Norefrina Shafinaz Md.; Ibrahim, Nazlina

    2015-09-01

    Styrylpyrone derivative (SPD) from Goniothalamus umbrosus has been shown to have antiviral properties against Herpes Simplex virus type-1 (HSV-1). This study aimed to evaluate the purity of isolated SPD and stability of SPD-incorporated formulations. Pure SPD was isolated from dried roots of G. umbrosus as confirmed by GC-MS. Two types of SPD-incorporated products (ointment and gel) were produced. Both products showed stable physical properties after two months and retained the SPD content for one month.

  7. A comprehensive study to evaluate the effect of constant low voltage iontophoresis on transungual delivery.

    PubMed

    Nair, Anroop B; Singh, Kishan; Shinu, Pottathil; Harsha, Sree; Al-Dhubiab, Bandar E

    2013-05-01

    Treatment of nail diseases by topical drug delivery continues to draw much attention in the recent days. This study aims to systematically investigate the effect of constant voltage iontophoresis in the transungual drug delivery, using ciclopirox as a model drug. Preliminary permeation studies were carried out by applying constant voltage (6 V for 24 h) using a gel formulation across the human nail plate in a Franz diffusion cell. Different protocols have been studied to authenticate the potential of the proposed technique. Antifungal studies were carried out to assess the pharmacodynamic effect of drug depot formed in the nail plate. Initial studies revealed that application of constant voltage iontophoresis enhanced the permeation by an order of magnitude (p = 0.019) and delivered significant amount of drug into the deeper nail layers. Noticeably higher permeation was observed during the active phase in on-off studies. Excellent correlation was observed in permeation (r(2) = 0.98) and drug load (r(2) = 0.97) with the increase in applied voltage (3-12 V), indicating that the current technique is predictable. The data observed suggest that any further increase in voltage could eventually lead to increase in the permeation and drug load, as the saturation level is very distant. Furthermore, the enhancement in permeation with the applied voltage (3-12 V) was found to be 6-20 folds, compared to the passive process. Results of step up and step down studies substantiated the viability of the current technique. Zone of inhibition measured during the antifungal studies demonstrated that the drug molecules loaded into the nail plate by low voltage iontophoresis is active and releases over an extended period of time (~32 days). Given the excellent results, the current technique could be used as an effective approach for the delivery of antimycotics, which would localize the drug at the infection site and potentially offer higher patient compliance. PMID:23057692

  8. Robust Voltage Stabilization in an Isolated Wind-Diesel Power System using PSO based-Fixed Structure H? Loop Shaping Control

    NASA Astrophysics Data System (ADS)

    Vachirasricirikul, Sitthidet; Ngamroo, Issarachai; Kaitwanidvilai, Somyot

    It is well known that the power system controller designed by H? control is complicated, high order and impractical. In power system applications, practical structures such as proportional integral derivative (PID) etc., are widely used, because of their simple structure, less number of tuning parameters and low-order. However, tuning of controller parameters to achieve a good performance and robustness is based on designer's experiences. To overcome this problem, this paper proposes a fixed structure robust H? loop shaping control to design Static Var Compensator (SVC) and Automatic Voltage Regulator (AVR) for robust stabilization of voltage fluctuation in an isolated wind-diesel hybrid power system. The structure of the robust controller of SVC and AVR is specified by a PID controller. In the system modeling, a normalized coprime factorization is applied to represent possible unstructured uncertainties in the power system such as variation of system parameters, generating and loading conditions etc. Based on the H? loop shaping, the performance and robust stability conditions are formulated as the optimization problem. The particle swarm optimization is applied to solve for PID control parameters of SVC and AVR simultaneously. Simulation studies confirm the control effect and robustness of the proposed control.

  9. Optical voltage reference

    DOEpatents

    Rankin, Richard (Ammon, ID); Kotter, Dale (Bingham County, ID)

    1994-01-01

    An optical voltage reference for providing an alternative to a battery source. The optical reference apparatus provides a temperature stable, high precision, isolated voltage reference through the use of optical isolation techniques to eliminate current and impedance coupling errors. Pulse rate frequency modulation is employed to eliminate errors in the optical transmission link while phase-lock feedback is employed to stabilize the frequency to voltage transfer function.

  10. Optical voltage reference

    DOEpatents

    Rankin, R.; Kotter, D.

    1994-04-26

    An optical voltage reference for providing an alternative to a battery source is described. The optical reference apparatus provides a temperature stable, high precision, isolated voltage reference through the use of optical isolation techniques to eliminate current and impedance coupling errors. Pulse rate frequency modulation is employed to eliminate errors in the optical transmission link while phase-lock feedback is employed to stabilize the frequency to voltage transfer function. 2 figures.

  11. Seismic stability evaluation of Alben Barkley Lock and Dam roject; Volume 5. Stability evaluation of geotechnical structures. Final report

    SciTech Connect

    Bluhm, P.F.; Wahl, R.E.; Olsen, R.S.

    1992-09-01

    This report describes the procedures used to interpret the data obtained from field investigations to determine the liquefaction potential and post-earthquake strengths of the foundation soils at the Alben Barkley Lock and Dam Project, Kentucky. The basic components of the report include the interpretation of field data to characterize the site and evaluate the foundation stratigraphy dynamic response analyses of two representative embankment sections, the analysis and interpretation of Cone and Standard Penetration Test data to determine the cyclic strengths for the evaluation of the liquefaction potential and the post earthquake strengths were input to the seismic stability analysis documented in Volume 5 of this series of reports.

  12. Performance evaluation of wideband bio-impedance spectroscopy using constant voltage source and constant current source

    NASA Astrophysics Data System (ADS)

    Mohamadou, Youssoufa; In Oh, Tong; Wi, Hun; Sohal, Harsh; Farooq, Adnan; Woo, Eung Je; McEwan, Alistair Lee

    2012-10-01

    Current sources are widely used in bio-impedance spectroscopy (BIS) measurement systems to maximize current injection for increased signal to noise while keeping within medical safety specifications. High-performance current sources based on the Howland current pump with optimized impedance converters are able to minimize stray capacitance of the cables and setup. This approach is limited at high frequencies primarily due to the deteriorated output impedance of the constant current source when situated in a real measurement system. For this reason, voltage sources have been suggested, but they require a current sensing resistor, and the SNR reduces at low impedance loads due to the lower current required to maintain constant voltage. In this paper, we compare the performance of a current source-based BIS and a voltage source-based BIS, which use common components. The current source BIS is based on a Howland current pump and generalized impedance converters to maintain a high output impedance of more than 1?M? at 2?MHz. The voltage source BIS is based on voltage division between an internal current sensing resistor (Rs) and an external sample. To maintain high SNR, Rs is varied so that the source voltage is divided more or less equally. In order to calibrate the systems, we measured the transfer function of the BIS systems with several known resistor and capacitor loads. From this we may estimate the resistance and capacitance of biological tissues using the least-squares method to minimize error between the measured transimpedance excluding the system transfer function and that from an impedance model. When tested on realistic loads including discrete resistors and capacitors, and saline and agar phantoms, the voltage source-based BIS system had a wider bandwidth of 10 Hz to 2.2 MHz with less than 1% deviation from the expected spectra compared to more than 10% with the current source. The voltage source also showed an SNR of at least 60 dB up to 2.2 MHz in comparison to the current source-based BIS system where the SNR drops below 40 dB for frequencies greater than 1 MHz.

  13. Evaluation of higher distribution and/or utilization voltages. Final report

    SciTech Connect

    Hazelrigg, Jr, George A.

    1981-01-01

    An electric energy distribution/utilization system cost analysis model is presented for exploring cost tradeoffs (capital innvestment, operation and maintenance and cost of losses) and optimizing system configuration. The model focuses on the treatment of residential and light commercial service areas with time-varying load characteristics, including customer load profile changes, per customer load growth and service area population growth. Applications of the model are discussed. These include providing insight on: the selection of primary and secondary voltages; conductor sizing; distribution transformer sizing, change out policies and copper-to-core-loss ratio; and limits on allowable voltage variation at the service entrance. Examples are provided to illustrate model capabilities.

  14. Program evaluation of a community crisis stabilization program.

    PubMed

    Boyer, Diane E; Kane, Catherine

    2010-12-01

    The purpose of this program evaluation was to evaluate the outcomes of treatment for participants in a community crisis stabilization (CCS) program. This CCS incorporated a patient-centered and wellness model of treatment. A descriptive study was conducted to assess change in psychological symptoms and quality of life of participants from admission to discharge. The sample (n = 42) was evaluated on admission and at discharge with four measurements: the Brief Symptoms Inventory (BSI), the Revised 24-Item Behavior and Symptom Identification Scale (BASIS-24), the Brief Psychiatric Rating Scale (BPRS), and the World Health Organization Quality of Life Scale-Brief Measure (WHOQOL-BREF). Changes in total scores on the BSI (t = 6.263, P < .001), the BASIS-24 (t = 6.964, P < .001), the BPRS (t = 4.638, P < .001), and the WHOQOL-BREF (t = 6.574, P < .001) demonstrated improvement at discharge. PMID:21111293

  15. Evaluation of motor-gasoline stability. Interim report

    SciTech Connect

    Stavinoha, L.L.; Bowden, J.N.; LePera, M.E.

    1990-12-01

    This report covers results of a storage program whose primary goal was the development of improved methods for evaluating motor gasoline stability. Several existing and potential predictive tests were applied to individual refinery components of gasoline, selected laboratory blends, and commercial gasolines for which ASTM D 525 induction periods ranged from 75 to 5000 minutes. Darkroom storage was conducted at 43 C, 54 C, and ambient temperatures, for various time periods with ambient storage ultimately reaching 4 years for most of the samples. Results confirm the findings of earlier researchers that ASTM D 525 is not viable as a predictive device by virtue of a low coefficient of determination between induction period and gum formed in storage at 43 C for periods up to 1 year. It is recognized, however, and ASTM D 525 is not likely to be abandoned as a specification stability test. Based upon the data generated under the four phases of this storage stability of commercial/military motor gasoline (produced for long term storage) is the ASTM D 873 Method using a 6-hour aging existent gum maximum limit of 5 mg/100 mL.

  16. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    SciTech Connect

    Wang, Qi; Wang, Junting; Lu, Qingyou; Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 ; Hou, Yubin

    2013-11-15

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d{sub 31} coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  17. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Hou, Yubin; Wang, Junting; Lu, Qingyou

    2013-11-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  18. Benchmarking the stability of human detergent-solubilised voltage-gated sodium channels for structural studies using eel as a reference.

    PubMed

    Slowik, Daria; Henderson, Richard

    2015-07-01

    With the ultimate goal of detailed structural analysis of mammalian and particularly human voltage-gated sodium channels (VGSCs), we have investigated the relative stability of human and rat VGSCs and compared them with electric eel VGSC. We found that NaV1.3 from rat was the most stable after detergent solubilisation. The order of stability was rNaV1.3>hNaV1.2>hNaV1.1>hNaV1.6>hNaV1.3>hNaV1.4. However, a comparison with the VGSC from Electrophorus electricus, which is most similar to NaV1.4, shows that the eel VGSC is considerably more stable in detergent than the human VGSCs examined. We conclude that current methods of structural analysis, such as single particle electron cryomicroscopy (cryoEM), may be most usefully targeted to eel VGSC or rNaV1.3, but that structural analysis on the full spectrum of VGSCs, by methods that require greater stability such as crystallisation and X-ray crystallography, will require further stabilisation of the channel. PMID:25838126

  19. Benchmarking the stability of human detergent-solubilised voltage-gated sodium channels for structural studies using eel as a reference

    PubMed Central

    Slowik, Daria; Henderson, Richard

    2015-01-01

    With the ultimate goal of detailed structural analysis of mammalian and particularly human voltage-gated sodium channels (VGSCs), we have investigated the relative stability of human and rat VGSCs and compared them with electric eel VGSC. We found that NaV1.3 from rat was the most stable after detergent solubilisation. The order of stability was rNaV1.3>hNaV1.2>hNaV1.1>hNaV1.6>hNaV1.3>hNaV1.4. However, a comparison with the VGSC from Electrophorus electricus, which is most similar to NaV1.4, shows that the eel VGSC is considerably more stable in detergent than the human VGSCs examined. We conclude that current methods of structural analysis, such as single particle electron cryomicroscopy (cryoEM), may be most usefully targeted to eel VGSC or rNaV1.3, but that structural analysis on the full spectrum of VGSCs, by methods that require greater stability such as crystallisation and X-ray crystallography, will require further stabilisation of the channel. PMID:25838126

  20. Synthesis and Evaluation of Hermitamides A and B as Human Voltage-Gated Sodium Channel Blockers

    PubMed Central

    De Oliveira, Eliseu O.; Graf, Kristin M.; Patel, Manoj K.; Baheti, Aparna; Kong, Hye-Sik; MacArthur, Linda H.; Dakshanamurthy, Sivanesan; Wang, Kan; Brown, Milton L.; Paige, Mikell

    2011-01-01

    Hermitamides A and B are lipopeptides isolated from a Papau New Guinea collection of the marine cyanobacterium Lyngbya majuscula. We hypothesized that the hermitamides are ligands for the human voltage-gated sodium channel (hNaV) based on their structural similarity to the jamaicamides. Herein, we describe the nonracemic total synthesis of hermitamides A and B and their epimers. We report the ability of the hermitamides to displace [3H]-BTX at 10 ?M more potently than phenytoin, a clinically used sodium channel blocker, a potential binding mode for (S)-hermitamide B in the BTX-binding site, and electrophysiology showing that these compounds are potent blockers of the hNav1.2 voltage-gated sodium channel. PMID:21683602

  1. Development and Evaluation of Transferrin-Stabilized Paclitaxel Nanocrystal Formulation

    PubMed Central

    Lu, Ying; Wang, Zhao-hui; Li, Tonglei; McNally, Helen; Park, Kinam; Sturek, Michael

    2014-01-01

    The aim of the present study was to prepare and evaluate a paclitaxel nanocrystal-based formulation stabilized by serum protein transferrin in a non-covalent manner. The pure paclitaxel nanocrystals were first prepared using an antisolvent precipitation method augmented by sonication. The serum protein transferrin was selected for use after evaluating the stabilizing effect of several serum proteins including albumin and immunoglobulin G. The formulation contained approximately 55~60% drug and was stable for at least 3 months at 4 °C. In vivo antitumor efficacy studies using mice inoculated with KB cells demonstrate significantly higher tumor inhibition rate of 45.1% for paclitaxel-transferrin formulation compared to 28.8% for paclitaxel nanosuspension treatment alone. Interestingly, the Taxol® formulation showed higher antitumor activity than the paclitaxel-transferrin formulation, achieving a 93.3% tumor inhibition rate 12 days post initial dosing. However, the paclitaxel-transferrin formulation showed a lower level of toxicity, which is indicated by steady increase in body weight of mice over the treatment period. In comparison, treatment with Taxol® resulted in toxicity issues as body weight decreased. These results suggest the potential benefit of using a serum protein in a non-covalent manner in conjunction with paclitaxel nanocrystals as a promising drug delivery model for anticancer therapy. PMID:24378441

  2. CT x-ray tube voltage optimisation and image reconstruction evaluation using visual grading analysis

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoming; Kim, Ted M.; Davidson, Rob; Lee, Seongju; Shin, Cheongil; Yang, Sook

    2014-03-01

    The purposes of this work were to find an optimal x-ray voltage for CT imaging and to determine the diagnostic effectiveness of image reconstruction techniques by using the visual grading analysis (VGA). Images of the PH-5 CT abdomen phantom (Kagaku Co, Kyoto) were acquired by the Toshiba Aquillion One 320 slices CT system with various exposures (from 10 to 580 mAs) under different tube peak voltages (80, 100 and 120 kVp). The images were reconstructed by employing the FBP and the AIDR 3D iterative reconstructions with Mild, Standard and Strong FBP blending. Image quality was assessed by measuring noise, contrast to noise ratio and human observer's VGA scores. The CT dose index CTDIv was obtained from the values displayed on the images. The best fit for the curves of the image quality VGA vs dose CTDIv is a logistic function from the SPSS estimation. A threshold dose Dt is defined as the CTDIv at the just acceptable for diagnostic image quality and a figure of merit (FOM) is defined as the slope of the standardised logistic function. The Dt and FOM were found to be 5.4, 8.1 and 9.1 mGy and 0.47, 0.51 and 0.38 under the tube voltages of 80, 100 and 120 kVp, respectively, from images reconstructed by the FBP technique. The Dt and FOM values were lower from the images reconstructed by the AIDR 3D in comparison with the FBP technique. The optimal xray peak voltage for the imaging of the PH-5 abdomen phantom by the Aquillion One CT system was found to be at 100 kVp. The images reconstructed by the FBP are more diagnostically effective than that by the AIDR 3D but with a higher dose Dt to the patients.

  3. A whole soil stability index (WSSI) for evaluating soil aggregation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil aggregate stability is an indicator of soil quality. However, there is no standard methodology for measuring soil aggregation or aggregate stability, particularly for determining a whole soil stability index. A whole soil stability index (WSSI) was developed here which combined data from dry ...

  4. Preliminary safety evaluation for the plutonium stabilization and packaging system

    SciTech Connect

    Shapley, J.E., Fluor Daniel Hanford

    1997-03-14

    This Preliminary Safety Evaluation (PSE) describes and analyzes the installation and operation of the Plutonium Stabilization and Packaging System (SPS) at the Plutonium Finishing Plant (PFP). The SPS is a combination of components required to expedite the safe and timely storage of Plutonium (Pu) oxide. The SPS program will receive site Pu packages, process the Pu for storage, package the Pu into metallic containers, and safely store the containers in a specially modified storage vault. The location of the SPS will be in the 2736- ZB building and the storage vaults will be in the 2736-Z building of the PFP, as shown in Figure 1-1. The SPS will produce storage canisters that are larger than those currently used for Pu storage at the PFP. Therefore, the existing storage areas within the PFP secure vaults will require modification. Other modifications will be performed on the 2736-ZB building complex to facilitate the installation and operation of the SPS.

  5. Evaluation of higher distribution and/or utilization voltages. Fourth interim report (August 1980): assessment of optimum distribution configuration

    SciTech Connect

    Not Available

    1981-04-01

    This interim report provides documentation on the fourth task, Assessment of Optimum Distribution Configuration, of DOE Contract No. ET-78-C-01-2866, Evaluation of Higher Distribution and/or Utilization Voltages. The work performed under this task includes the development of a computer model for assessment of life cycle costs for the distribution and utilization systems, the development of an optimization algorithm to enable distribution system configuration optimization and a net energy analysis to determine potential net energy savings. Input data for this task derive from Task 3. The major output of this task is a documented computer code.

  6. Imaging Quality Evaluation of Low Tube Voltage Coronary CT Angiography Using Low Concentration Contrast Medium

    PubMed Central

    Zhang, Zaixian; Wang, Qingguo; Zheng, Linfeng; Feng, Yan; Zhou, Zhiguo; Zhang, Guixiang; Li, Kangan

    2015-01-01

    Purpose To compare the image quality of prospectively ECG-gated low voltage coronary computed tomography angiography (CTA) with an administration of low concentration contrast medium. Method and Materials A total of 101 patients, each with a heart rate below 65 beats per minute (BPM), underwent a prospectively ECG-gated axial scan in CT coronary angiography on a 64-slice CT scanner. All patients were allocated in three groups (group A: n=31, 80kVp, 300 mgI/ml; group B: n=34, 100kVp, 300 mgI/ml; group C: n=36, 120kVp, 370 mgI/ml). The CT attenuation values of aortic root (AR), left main coronary artery (LMA), right main coronary artery (RMA) and chest subcutaneous fat tissue were measured. The contrast-to-noise ratio (CNR) of AR, LMA and RMA were calculated according to the formulas below. The values of computed tomography dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was assessed on a 5-point scale. The results were compared using the one-way ANOVA and rank sum tests. Results The values of CNR and SNR for vessels in group A and group B were not significantly different from group C (each p > 0.05). The effective radiation dose in group A (1.510.70 mSv) and group B (2.591.24 mSv) were both lower than group C (4.922.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.100.41), group B (3.900.48) and group C (4.040.36) (each P > 0.05). Conclusion Low tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium. Meanwhile low concentration contrast medium allowed 47-69% of radiation dose reduction. PMID:25811785

  7. Evaluating Sediment Stability at Offshore Marine Hydrokinetic Energy Facilities

    NASA Astrophysics Data System (ADS)

    Jones, C. A.; Magalen, J.; Roberts, J.; Chang, G.

    2014-12-01

    Development of offshore alternative energy production methods through the deployment of Marine Hydrokinetic (MHK) devices (e.g. wave, tidal, and wind generators) in the United States continues at a rapid pace, with significant public and private investment in recent years. The installation of offshore MHK systems includes cabling to the shoreline and some combination of bottom foundation (e.g., piles, gravity bases, suction buckets) or anchored floating structure. Installation of any of this infrastructure at the seabed may affect coastal sediment dynamics. It is, therefore, necessary to evaluate the interrelationships between hydrodynamics and seabed dynamics and the effects of MHK foundations and cables on sediment transport. If sufficient information is known about the physical processes and sediment characteristics of a region, hydrodynamic and sediment transport models may be developed to evaluate near and far-field sediment transport. The ultimate goal of these models and methods is to quantitatively evaluate changes to the baseline seabed stability due to the installation of MHK farms in the water. The objective of the present study is to evaluate and validate wave, current, and sediment transport models (i.e., a site analysis) that may be used to estimate risk of sediment mobilization and transport. While the methodology and examples have been presented in a draft guidance document (Roberts et al., 2013), the current report presents an overall strategy for model validation, specifically for a case study in the Santa Cruz Bight, Monterey Bay, CA. Innovative techniques to quantify the risk of sediment mobility has been developed to support these investigations. Public domain numerical models are utilized to estimate the near-shore wave climate (SWAN: Simulating Waves Near-shore) and circulation and sediment transport (EFDC: Environmental Fluid Dynamics Code) regimes. The models were validated with field hydrodynamic data. Sediment size information was provided by the USGS usSEABED sediment database program. Near-bottom current- and wave-induced shear stresses were computed and used directly to derive a sediment mobilization risk relationship.

  8. Passive protection devices for high-voltage equipment: Design procedures and performance evaluation

    SciTech Connect

    Serino, G.; Bonacina, G.; Bettinali, F.

    1995-12-31

    A 420 kV High-Voltage Alternating Current Circuit-Breaker, a typical element of an open-air electrical substation, is considered. Experimental tests carried out on such a piece of equipment by ISMES, under ENEL support, clearly pointed out its inability to withstand the seismic qualification level of highest severity indicated by the standards. The design of a seismic isolation system for the switch-gear composed of spring units and dampers is developed in this paper, and the dynamic earthquake response of the isolated circuit-breaker is compared numerically to the one obtained without the seismic protection system. The remarkable reduction of stresses in the porcelain insulators are shown, evidencing that this occurs to the detriment of a certain increment of displacements at the top of the apparatus.

  9. Demonstration and Field Evaluation of Streambank Stabilization with Submerged Vanes

    USGS Publications Warehouse

    Whitman, H.; Hoopes, J.; Poggi, D.; Fitzpatrick, F.; Walz, K.

    2001-01-01

    The effectiveness of submerged vanes for reducing bank erosion and improving aquatic habitat is being evaluated at a site on North Fish Creek, a Lake Superior tributary. Increased runoff from agricultural areas with clayey soils has increased flood magnitudes and the erosion potential/transport capacity of the stream. Most of the creek's sediment load originates from the erosion of 17 large bluffs. This creek contains important recreational fisheries that are potentially limited by the loss of aquatic habitat from deposition of sediment on spawning beds. Submerged vanes are a cost effective and environmentally less intrusive alternative to traditional structural stabilization measures. Submerged vanes protrude from a channel bed, are oriented at an angle to the local velocity, and are distributed along a portion of channel. They induce a transverse force and torque on the flow along with longitudinal vortexes that alter the cross sectional shape and alignment of the channel. Submerged vanes were installed at a bluff/bend site in summer and fall 2000. The number, size, and layout of the vanes were based upon the channel morphology under estimated bankfull conditions. The effectiveness of the vanes will be evaluated by comparing surveys of the bluff face, streamflow, and channel conditions for several years after installation of the submerged vanes with surveys before and immediately after their installation.

  10. Evaluation of tunnel stability using integrated geophysical methods

    NASA Astrophysics Data System (ADS)

    Cardarelli, E.; Marrone, C.; Orlando, L.

    2003-02-01

    An integrated interpretation was made of data, from ground penetrating radar (GPR), seismic refraction and seismic transmission tomography, collected inside the catchment tunnels of a potable water source in central Italy. Rock fracturing and obsolescence of the concrete lining in a tunnel led a landslide that caused structural instability in the catchment work structures. To assess the stability of the rock close to the landslide, geophysical surveys were preferred to boreholes and geotechnical tests in order to avoid water pollution and the risk of further landslides. The interpretation of integrated data from seismic tomography and 200 MHz antenna GPR resulted in an evaluation of some of the elastic characteristics and the detection of discontinuities in the rock. Note also that an analysis of the back-scattered energy was required for the GPR data interpretation. The integration of seismic refraction data and 450 MHz antenna allowed us to identify the loosened zone around the tunnel and the extent of the mass involved in the cave-in, while GPR data from 225 MHz were used to evaluate the quality of contact between concrete lining and massive rock.

  11. HEMC: A sensitive aggregate stability method for soil quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil aggregate stability is an important soil quality index, representing mainly soil structural stability and affecting, among others, hydraulic conductivity, seal formation, runoff, water and wind erosion. The most common method of assessing aggregate stability is wet sieving where aggregate stabi...

  12. Modelling of illuminated current–voltage characteristics to evaluate leakage currents in long wavelength infrared mercury cadmium telluride photovoltaic detectors

    SciTech Connect

    Gopal, Vishnu E-mail: wdhu@mail.sitp.ac.cn; Qiu, WeiCheng; Hu, Weida E-mail: wdhu@mail.sitp.ac.cn

    2014-11-14

    The current–voltage characteristics of long wavelength mercury cadmium telluride infrared detectors have been studied using a recently suggested method for modelling of illuminated photovoltaic detectors. Diodes fabricated on in-house grown arsenic and vacancy doped epitaxial layers were evaluated for their leakage currents. The thermal diffusion, generation–recombination (g-r), and ohmic currents were found as principal components of diode current besides a component of photocurrent due to illumination. In addition, both types of diodes exhibited an excess current component whose growth with the applied bias voltage did not match the expected growth of trap-assisted-tunnelling current. Instead, it was found to be the best described by an exponential function of the type, I{sub excess} = I{sub r0} + K{sub 1} exp (K{sub 2} V), where I{sub r0}, K{sub 1}, and K{sub 2} are fitting parameters and V is the applied bias voltage. A study of the temperature dependence of the diode current components and the excess current provided the useful clues about the source of origin of excess current. It was found that the excess current in diodes fabricated on arsenic doped epitaxial layers has its origin in the source of ohmic shunt currents. Whereas, the source of excess current in diodes fabricated on vacancy doped epitaxial layers appeared to be the avalanche multiplication of photocurrent. The difference in the behaviour of two types of diodes has been attributed to the difference in the quality of epitaxial layers.

  13. Evaluation of electronic stability control effectiveness in Australasia.

    PubMed

    Scully, Jim; Newstead, Stuart

    2008-11-01

    Electronic stability control (ESC) is an in-vehicle technology aimed at improving primary safety by assisting the driver in avoiding loss of control of the vehicle. The aim of this study was to use available crash data from Australia and New Zealand to evaluate the effectiveness of ESC in reducing crash risk and to establish whether benefits estimated from overseas studies have translated to the Australian and New Zealand environments. The sample analysed included 7699 crashed vehicles fitted with ESC which comprised of 90 different models. Poisson regression was used to test whether the differences in the observed and expected crash counts for ESC fitted vehicles were significant, with exposure being induced from counts of rear end impacts. It was found that ESC reduced the risk of single vehicle crashes in which the driver was injured by 68% for 4WDs compared with 27% for passenger cars. The effect of ESC on multiple vehicle crashes in Australia and New Zealand was not clear. The long-term benefits of fitting ESC to all vehicles in Australia were also investigated based on the estimated single vehicle crash reductions. PMID:19068314

  14. Stability evaluation of lutein nanodispersions prepared via solvent displacement method: The effect of emulsifiers with different stabilizing mechanisms.

    PubMed

    Tan, Tai Boon; Yussof, Nor Shariffa; Abas, Faridah; Mirhosseini, Hamed; Nehdi, Imededdine Arbi; Tan, Chin Ping

    2016-08-15

    The stability of lutein nanodispersions was evaluated during storage and when exposed to different environmental conditions. Lutein nanodispersions were prepared using Tween 80, sodium dodecyl sulfate (SDS), sodium caseinate (SC) and SDS-Tween 80 as the emulsifiers. During eight weeks of storage, all samples showed remarkable physical stability. However, only the SC-stabilized nanodispersion showed excellent chemical stability. Under different environmental conditions, the nanodispersions exhibited a varied degree of stability. All nanodispersions showed constant particle sizes at temperatures between 30 and 60°C. However, at pH 2-8, only the SC-stabilized nanodispersion was physically unstable. The addition of NaCl (300-400mM) only caused flocculation in nanodispersion stabilized by SDS-Tween 80. All nanodispersions were physically stable when subjected to different centrifugation speeds. Only Tween 80-stabilized nanodispersion was stable against the effect of freeze-thaw cycles (no phase separation observed). In this study, there was no particular emulsifier that was effective against all of the environmental conditions tested. PMID:27006226

  15. SiNWs-based electrochemical double layer micro-supercapacitors with wide voltage window (4 V) and long cycling stability using a protic ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Aradilla, David; Gentile, Pascal; Ruiz, Vanesa; Gmez-Romero, Pedro; Wimberg, Jan; Iliev, Boyan; Schubert, Thomas J. S.; Sadki, Sad; Bidan, Grard

    2015-03-01

    The present work reports the use and application of a novel protic ionic liquid (triethylammonium bis(trifluoromethylsulfonyl)imide; NEt3H TFSI) as an electrolyte for symmetric planar micro-supercapacitors based on silicon nanowire electrodes. The excellent performance of the device has been successfully demonstrated using cyclic voltammetry, galvanostatic charge-discharge cycles and electrochemical impedance spectroscopy. The electrochemical characterization of this system exhibits a wide operative voltage of 4 V as well as an outstanding long cycling stability after millions of galvanostatic cycles at a high current density of 2 mA cm-2. In addition, the electrochemical double layer micro-supercapacitor was able to deliver a high power density of 4 mW cm-2 in a very short time pulses (a few ms). Our results could be of interest to develop prospective on-chip micro-supercapacitors using protic ionic liquids as electrolytes with high performance in terms of power and energy densities. Invited talk at the 2nd International Workshop on Nano Materials for Energy Conversion NMEC-2, 17-20 November, 2014, Ho Chi Minh City, Vietnam.

  16. Tris(trimethylsilyl)borate as an electrolyte additive for improving interfacial stability of high voltage layered lithium-rich oxide cathode/carbonate-based electrolyte

    NASA Astrophysics Data System (ADS)

    Li, Jianhui; Xing, Lidan; Zhang, Ruiqin; Chen, Min; Wang, Zaisheng; Xu, Mengqing; Li, Weishan

    2015-07-01

    Tris(trimethylsilyl)borate (TMSB) is used as an electrolyte additive for high voltage lithium-rich oxide cathode of lithium ion battery. The interfacial natures of Li[Li0.2Mn0.54Ni0.13Co0.13]O2/carbonate-based electrolyte are investigated with a combination of electrochemical measurements and physical characterizations. Charge/discharge tests show that the cyclic performance of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 in a mixed carbonate electrolyte is significantly improved by using TMSB. After 200 cycles between 2 V and 4.8 V (vs. Li/Li+) at 0.5 C rate, the capacity retention of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is only 19% in the blank electrolyte, while it is improved to 74% when 0.5% TMSB is applied. The results from physical characterizations demonstrate that this excellent cyclic performance is attributed to the improved interfacial stability of Li[Li0.2Mn0.54Ni0.13Co0.13]O2/electrolyte due to the thin and protective film generated by TMSB.

  17. Evaluation of modulating field of photoreflectance of surface-intrinsic-n+ type doped GaAs by using photoinduced voltage

    NASA Astrophysics Data System (ADS)

    Lee, W. Y.; Chien, J. Y.; Wang, D. P.; Huang, K. F.; Huang, T. C.

    2002-04-01

    Photoreflectance (PR) of surface-intrinsic-n+ type doped GaAs has been measured for various power densities of pump laser. The spectra exhibited many Franz-Keldysh oscillations, whereby the strength of electric field F in the undoped layer can be determined. The thus obtained Fs are subject to photovoltaic effect and are less than built-in field Fbi. In the previous work we have obtained the relation F≈Fbi-δF/2 when δF≪Fbi by using electroreflectance to simulate PR, where δF is the modulating field of the pump beam. In this work a method was devised to evaluate δF by using photoinduced voltages Vs and, hence, the relation can be verified by PR itself. The δFs obtained by Vs are also consistent with those of using imaginary part of fast Fourier transform of PR spectra.

  18. Evaluation of a Programmable Voltage-Controlled MEMS Oscillator, Type SiT3701, Over a Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2009-01-01

    Semiconductor chips based on MEMS (Micro-Electro-Mechanical Systems) technology, such as sensors, transducers, and actuators, are becoming widely used in today s electronics due to their high performance, low power consumption, tolerance to shock and vibration, and immunity to electro-static discharge. In addition, the MEMS fabrication process allows for the miniaturization of individual chips as well as the integration of various electronic circuits into one module, such as system-on-a-chip. These measures would simplify overall system design, reduce parts count and interface, improve reliability, and reduce cost; and they would meet requirements of systems destined for use in space exploration missions. In this work, the performance of a recently-developed MEMS voltage-controlled oscillator was evaluated under a wide temperature range. Operation of this new commercial-off-the-shelf (COTS) device was also assessed under thermal cycling to address some operational conditions of the space environment

  19. An implementation of particle swarm optimization to evaluate optimal under-voltage load shedding in competitive electricity markets

    NASA Astrophysics Data System (ADS)

    Hosseini-Bioki, M. M.; Rashidinejad, M.; Abdollahi, A.

    2013-11-01

    Load shedding is a crucial issue in power systems especially under restructured electricity environment. Market-driven load shedding in reregulated power systems associated with security as well as reliability is investigated in this paper. A technoeconomic multi-objective function is introduced to reveal an optimal load shedding scheme considering maximum social welfare. The proposed optimization problem includes maximum GENCOs and loads' profits as well as maximum loadability limit under normal and contingency conditions. Particle swarm optimization (PSO) as a heuristic optimization technique, is utilized to find an optimal load shedding scheme. In a market-driven structure, generators offer their bidding blocks while the dispatchable loads will bid their price-responsive demands. An independent system operator (ISO) derives a market clearing price (MCP) while rescheduling the amount of generating power in both pre-contingency and post-contingency conditions. The proposed methodology is developed on a 3-bus system and then is applied to a modified IEEE 30-bus test system. The obtained results show the effectiveness of the proposed methodology in implementing the optimal load shedding satisfying social welfare by maintaining voltage stability margin (VSM) through technoeconomic analyses.

  20. Safety evaluation of interim stabilization of non-stabilized single-shell watch list tanks

    SciTech Connect

    Stahl, S.M.

    1994-12-30

    The report provides a summation of the status of safety issues associated with interim stabilization of Watch List SSTs (organic, ferrocyanide, and flammable gas), as extracted from recent safety analyses, including the Tank Farms Accelerated Safety Analysis efforts.

  1. Non-iterative Voltage Stability

    SciTech Connect

    Makarov, Yuri V.; Vyakaranam, Bharat; Hou, Zhangshuan; Wu, Di; Meng, Da; Wang, Shaobu; Elbert, Stephen T.; Miller, Laurie E.; Huang, Zhenyu

    2014-09-30

    This report demonstrates promising capabilities and performance characteristics of the proposed method using several power systems models. The new method will help to develop a new generation of highly efficient tools suitable for real-time parallel implementation. The ultimate benefit obtained will be early detection of system instability and prevention of system blackouts in real time.

  2. EVALUATION OF SOLIDIFICATION/STABILIZATION AS A BEST DEMONSTRATED AVAILABLE TECHNOLOGY FOR CONTAMINATED SOILS

    EPA Science Inventory

    This project involved the evaluation of solidification/stabilization technology as a BDAT for contaminated soil. Three binding agents were used on four different synthetically contaminated soils. Performance evaluation data included unconfined compressive strength (UCS) and the T...

  3. Voltage Sensor

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Under a Lewis Research Center Small Business Innovation Research contract, SRICO, Inc. developed a fiber optic voltage sensor to measure voltage in electronic systems in spacecraft. The sensor uses glass and light to sense and transmit electricity, and is relatively safe and accurate. SRICO then commercialized the sensor for measurement of electric field and voltage in applications such as electric power systems and hazardous environments, lightning detection, and fiber optic communication systems.

  4. VOLTAGE REGULATOR

    DOEpatents

    Von Eschen, R.L.; Scheele, P.F.

    1962-04-24

    A transistorized voltage regulator which provides very close voitage regulation up to about 180 deg F is described. A diode in the positive line provides a constant voltage drop from the input to a regulating transistor emitter. An amplifier is coupled to the positive line through a resistor and is connected between a difference circuit and the regulating transistor base which is negative due to the difference in voltage drop across thc diode and the resistor so that a change in the regulator output causes the amplifier to increase or decrease the base voltage and current and incrcase or decrease the transistor impedance to return the regulator output to normal. (AEC)

  5. Electrical/mechanical evaluation of high voltage dielectrics for OTEC riser cables

    SciTech Connect

    Traut, R. T.; Kurt, J. P.; DiPietro, F. M.; Roberts, K. P.

    1980-01-01

    The unique design and test requirements for the cable dielectrics selected for evaluation for use in Ocean Thermal Energy Conversion plants are described. Specifically, the methodology of developing the test procedure is defined. The basic cable dielectrics selected for evaluation include taped/oil-impregnated insulation, and extruded solid cross-linked polyethylene insulation. These cables are designed to transmit 100 MW at 138 kV, and will be subjected to installation and operating conditions that are unprecedented for any power cable system. These conditions include ocean depths of 4000 to 5000 feet, long vertical suspension, and the motions and forces imparted by the plant and ocean. The developmental test program is designed primarily to determine the weak link in the components of the candidate cable with regard to the ability to successfully withstand the unusual OTEC conditions over a 10 to 30 year lifetime. Two basic areas of concern are the mechanical fatigue of metallic sheaths and strength members, and the electrical/mechanical ''fatigue'' of the dielectric and shielding components. The constraints and problems in such testing are addressed, and the engineering solutions are described. Finally, the scheduled plan for completion of the entire development test plan is defined.

  6. Evaluation of accelerated stability test conditions for medicated chewing gums.

    PubMed

    Maggi, Lauretta; Conte, Ubaldo; Nhamias, Alain; Grenier, Pascal; Vergnault, Guy

    2013-10-01

    The overall stability of medicated chewing gums is investigated under different storage conditions. Active substances with different chemical stabilities in solid state are chosen as model drugs. The dosage form is a three layer tablet obtained by direct compression. The gum core contains the active ingredient while the external layers are formulated to prevent gum adhesion to the punches of the tableting machine. Two accelerated test conditions (40°C/75% RH and 30°C/65% RH) are performed for 6 months. Furthermore, a long-term stability test at room conditions is conducted to verify the predictability of the results obtained from the stress tests. Some drugs are stable in all the conditions tested, but other drugs, generally considered stable in solid dosage forms, have shown relevant stability problems particularly when stress test conditions are applied to this particular semi-solid dosage forms. For less stable drugs, the stress conditions of 40°C/75% RH are not always predictable of chewing gum stability at room temperature and may produce false negative; intermediate conditions, 30°C/65% RH, are more predictive for this purpose, the results of drug content found after 6 months at intermediate stress conditions and 12 months at room conditions are generally comparable. But the results obtained show that only long-term conditions stability tests gave consistent results. During aging, the semi solid nature of the gum base itself, may also influence the drug delivery rate during chewing and great attention should be given also to the dissolution stability. PMID:22794248

  7. AN EVALUATION OF CONDITION MONITORING TECHNIQUES FOR LOW-VOLTAGE ELECTRIC CABLES

    SciTech Connect

    LOFARO,R.J.; GROVE,E.; SOO,P.

    2000-07-23

    Aging of systems and components in nuclear power plants is a well known occurrence that must be managed to ensure the continued safe operation of these plants. Much of the degradation due to aging is controlled through periodic maintenance and/or component replacement. However, there are components that do not receive periodic maintenance or monitoring once they are installed; electric cables are such a component. To provide a means of monitoring the condition of electric cables, research is ongoing to evaluate promising condition monitoring (CM) techniques that can be used in situ to monitor cable condition and predict remaining life. While several techniques are promising, each has limitations that must be considered in its application. This paper discusses the theory behind several of the promising cable CM techniques being studied, along with their effectiveness for monitoring aging degradation in typical cable insulation materials, such as cross-linked polyethylene and ethylene propylene rubber. Successes and limitations of each technique are also presented.

  8. A Polybasic Plasma Membrane Binding Motif in the I-II Linker Stabilizes Voltage-gated CaV1.2 Calcium Channel Function*

    PubMed Central

    Kaur, Gurjot; Pinggera, Alexandra; Ortner, Nadine J.; Lieb, Andreas; Sinnegger-Brauns, Martina J.; Yarov-Yarovoy, Vladimir; Obermair, Gerald J.; Flucher, Bernhard E.; Striessnig, Jörg

    2015-01-01

    L-type voltage-gated Ca2+ channels (LTCCs) regulate many physiological functions like muscle contraction, hormone secretion, gene expression, and neuronal excitability. Their activity is strictly controlled by various molecular mechanisms. The pore-forming α1-subunit comprises four repeated domains (I–IV), each connected via an intracellular linker. Here we identified a polybasic plasma membrane binding motif, consisting of four arginines, within the I-II linker of all LTCCs. The primary structure of this motif is similar to polybasic clusters known to interact with polyphosphoinositides identified in other ion channels. We used de novo molecular modeling to predict the conformation of this polybasic motif, immunofluorescence microscopy and live cell imaging to investigate the interaction with the plasma membrane, and electrophysiology to study its role for Cav1.2 channel function. According to our models, this polybasic motif of the I-II linker forms a straight α-helix, with the positive charges facing the lipid phosphates of the inner leaflet of the plasma membrane. Membrane binding of the I-II linker could be reversed after phospholipase C activation, causing polyphosphoinositide breakdown, and was accelerated by elevated intracellular Ca2+ levels. This indicates the involvement of negatively charged phospholipids in the plasma membrane targeting of the linker. Neutralization of four arginine residues eliminated plasma membrane binding. Patch clamp recordings revealed facilitated opening of Cav1.2 channels containing these mutations, weaker inhibition by phospholipase C activation, and reduced expression of channels (as quantified by ON-gating charge) at the plasma membrane. Our data provide new evidence for a membrane binding motif within the I-II linker of LTCC α1-subunits essential for stabilizing normal Ca2+ channel function. PMID:26100638

  9. A Polybasic Plasma Membrane Binding Motif in the I-II Linker Stabilizes Voltage-gated CaV1.2 Calcium Channel Function.

    PubMed

    Kaur, Gurjot; Pinggera, Alexandra; Ortner, Nadine J; Lieb, Andreas; Sinnegger-Brauns, Martina J; Yarov-Yarovoy, Vladimir; Obermair, Gerald J; Flucher, Bernhard E; Striessnig, Jrg

    2015-08-21

    L-type voltage-gated Ca(2+) channels (LTCCs) regulate many physiological functions like muscle contraction, hormone secretion, gene expression, and neuronal excitability. Their activity is strictly controlled by various molecular mechanisms. The pore-forming ?1-subunit comprises four repeated domains (I-IV), each connected via an intracellular linker. Here we identified a polybasic plasma membrane binding motif, consisting of four arginines, within the I-II linker of all LTCCs. The primary structure of this motif is similar to polybasic clusters known to interact with polyphosphoinositides identified in other ion channels. We used de novo molecular modeling to predict the conformation of this polybasic motif, immunofluorescence microscopy and live cell imaging to investigate the interaction with the plasma membrane, and electrophysiology to study its role for Cav1.2 channel function. According to our models, this polybasic motif of the I-II linker forms a straight ?-helix, with the positive charges facing the lipid phosphates of the inner leaflet of the plasma membrane. Membrane binding of the I-II linker could be reversed after phospholipase C activation, causing polyphosphoinositide breakdown, and was accelerated by elevated intracellular Ca(2+) levels. This indicates the involvement of negatively charged phospholipids in the plasma membrane targeting of the linker. Neutralization of four arginine residues eliminated plasma membrane binding. Patch clamp recordings revealed facilitated opening of Cav1.2 channels containing these mutations, weaker inhibition by phospholipase C activation, and reduced expression of channels (as quantified by ON-gating charge) at the plasma membrane. Our data provide new evidence for a membrane binding motif within the I-II linker of LTCC ?1-subunits essential for stabilizing normal Ca(2+) channel function. PMID:26100638

  10. Technical evaluation report on the adequacy of station electric distribution system voltages for the Peach Bottom Atomic Power Station. Units 2 and 3

    SciTech Connect

    White, R.L.

    1982-06-21

    This report documents the technical evaluation of the adequacy of the station electric distribution system voltages for the Peach Bottom Atomic Power Station, Units 2 and 3. The evaluation is to determine if the onsite distribution system, in conjunction with the offsite power sources, has sufficient capacity to automatically start and operate all Class 1E loads within the equipment voltage ratings under certain conditions established by the Nuclear Regulatory Commission. The analysis submitted indicates that the capacity is sufficient to meet the NRC requirements provided specific plant procedures are followed for shutting down the second unit after an accident in the first unit and with a loss of one offsite source.

  11. Evaluation of write error rate for voltage-driven dynamic magnetization switching in magnetic tunnel junctions with perpendicular magnetization

    NASA Astrophysics Data System (ADS)

    Shiota, Yoichi; Nozaki, Takayuki; Tamaru, Shingo; Yakushiji, Kay; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji; Suzuki, Yoshishige

    2016-01-01

    We investigated the write error rate (WER) for voltage-driven dynamic switching in magnetic tunnel junctions with perpendicular magnetization. We observed a clear oscillatory behavior of the switching probability with respect to the duration of pulse voltage, which reveals the precessional motion of magnetization during voltage application. We experimentally demonstrated WER as low as 4 10?3 at the pulse duration corresponding to a half precession period (?1 ns). The comparison between the results of the experiment and simulation based on a macrospin model shows a possibility of ultralow WER (<10?15) under optimum conditions. This study provides a guideline for developing practical voltage-driven spintronic devices.

  12. [Concepts, evaluation methods, diagnostic and prognostic values of implant stability].

    PubMed

    Grognard, Nicolas; Vande Vannet, Bart

    2010-01-01

    The outcome of oral implant treatment is in part focused on the obtained implant stability as outlined in the success criteria as propose by Albrektsson T. & Albrektsson B. (1987) and by Buser et al. (1997). In those criteria, clinical diagnostic testing of implant stability is a rather crude and subjective procedure. Quantitative measurement technology, such as the Periotest and the Osstell Mentor devices do provide more refined and objective tools to diagnose and monitor the state of osseointegration. On the other hand, their power to predict treatment outcome is rather low. PMID:20556937

  13. Evaluating competing forces constraining glacial grounding-line stability (Invited)

    NASA Astrophysics Data System (ADS)

    Powell, R. D.

    2013-12-01

    Stability of grounding lines of marine-terminating glaciers and ice sheets is of concern due to their importance in governing rates of ice mass loss and consequent sea level rise during global warming. Although processes are similar at tidewater and floating grounding zones their relative magnitudes in terms of their influence on grounding-line stability vary between these two end members. Processes considered Important for this discussion are ice dynamics, ice surface melting and crevassing, ocean dynamics, subglacial sediment and water dynamics, and subglacial bed geometries. Models have continued to improve in their representation of these complex interactions but reliable field measurements and data continue to be hard earned and too few to properly constrain the range of boundary conditions in this complicated system. Some data will be presented covering a range of regimes from Alaska, Svalbard and Antarctica. Certainly more data are required on subglacial sediment/water dynamics and fluxes to fully represent the spectrum of glacial regimes and to assess the significance of grounding-zone sediment systems in counteracting the other processes to force grounding-line stability. Especially important here is constraining the duration of the stability that could be maintained by sediment flux - present data appear to show that it is likely to be a limited period.

  14. Evaluation of HAN-TEAN Stabilizers using Microcalorimetry

    NASA Technical Reports Server (NTRS)

    Hornung, Steven D.; Davis, Dennis D.; Chang, Craig H.; Baker, David L.

    1997-01-01

    HAN-TEAN (hydroxylammonium nitrate - triethanolammonium nitrate - in water) is being considered for various propellant applications. This propellant has advantages in terms of insensitivity to impact and fire, low vapor pressure and environmentally benign reaction products. One office concerns with HAN-TEAN is its stability and shelf-life, especially when contaminated with trace metals. Stabilizer systems, consisting of anti-oxidants and/or chealating agents were investigated for their ability to control the decomposition of HAN-TEAN. Isothermal microcalorimetry, an ultrasensitive heat measurement technique, was used to monitor the decomposition of HANTEAN at near ambient temperatures. Isothermal microcalorimetry measures the heat flow from a reaction vessel into a surrounding heat sink. Microcalorimetry is approximately 1,000 times more sensitive than accelerating rate calorimetry (ARC) or differential scanning calorimetry (DSC) for measuring heat flow. Samples of HAN-TEAN containing the stabilizers were spiked with 50 ppm iron and the heat evolution monitored for a period of at least 30 days. Ten stabilizer combinations were tested and the rates of HAN-TEAN decomposition were lowered by 74 to 95 percent in the presence of iron.

  15. Evaluation of the stability of gas hydrates in Northern Alaska

    USGS Publications Warehouse

    Kamath, A.; Godbole, S.P.; Ostermann, R.D.; Collett, T.S.

    1987-01-01

    The factors which control the distribution of in situ gas hydrate deposits in colder regions such as Northern Alaska include; mean annual surface temperatures (MAST), geothermal gradients above and below the base of permafrost, subsurface pressures, gas composition, pore-fluid salinity and the soil condition. Currently existing data on the above parameters for the forty-six wells located in Northern Alaska were critically examined and used in calculations of depths and thicknesses of gas hydrate stability zones. To illustrate the effect of gas hydrate stability zones, calculations were done for a variable gas composition using the thermodynamic model of Holder and John (1982). The hydrostatic pressure gradient of 9.84 kPa/m (0.435 lbf/in2ft), the salinity of 10 parts per thousand (ppt) and the coarse-grained soil conditions were assumed. An error analysis was performed for the above parameters and the effect of these parameters on hydrate stability zone calculations were determined. After projecting the hydrate stability zones for the forty-six wells, well logs were used to identify and to obtain values for the depth and thickness of hydrate zones. Of the forty-six wells, only ten wells showed definite evidence of the presence of gas hydrates. ?? 1987.

  16. Evaluation on oxidative stability of walnut beverage emulsions.

    PubMed

    Liu, Shuang; Liu, Fuguo; Xue, Yanhui; Gao, Yanxiang

    2016-07-15

    Walnut beverage emulsions were prepared with walnut kernels, mixed nonionic emulsifiers and xanthan gum. The effects of food antioxidants on the physical stability and lipid oxidation of walnut beverage emulsions were investigated. The results showed that tea polyphenols could not only increase the droplet size of the emulsions, but also enhance physical stability during the thermal storage at 62±1°C. However, water-dispersed oil-soluble vitamin E and enzymatically modified isoquercitrin obviously decreased the physical stability of the emulsion system during the thermal storage. BHT and natural antioxidant extract had scarcely influenced on the physical stability of walnut beverage emulsions. Tea polyphenols and BHT could significantly retard lipid oxidation in walnut beverage emulsions against thermal and UV light exposure during the storage. Vitamin E exhibited the prooxidant effect during the thermal storage and the antioxidant attribute during UV light exposure. Other food antioxidants had no significant effect on retarding lipid oxidation during thermal or light storage. PMID:26948632

  17. Lithium-cyclo-difluoromethane-1,1-bis(sulfonyl)imide as a stabilizing electrolyte additive for improved high voltage applications in lithium-ion batteries.

    PubMed

    Murmann, Patrick; Streipert, Benjamin; Kloepsch, Richard; Ignatiev, Nikolai; Sartori, Peter; Winter, Martin; Cekic-Laskovic, Isidora

    2015-04-14

    Lithium-cyclo-difluoromethane-1,1-bis(sulfonyl)imide (LiDMSI) was evaluated as an electrolyte additive in lithium-ion batteries for improved high voltage applications. Cycling the cathode at high potentials leads to the electrochemical oxidation of the salt to form a cathode electrolyte interphase (CEI) layer on the cathode surface. With the addition of 2 wt% of LiDMSI to the 1 M LiPF6 in 1 : 1 (by wt) EC : DEC electrolyte, the capacity retention and the Coulombic efficiency in LiNi1/3Co1/3Mn1/3O2/Li-half-cells as well as in LiNi1/3Co1/3Mn1/3O2/graphite-full-cells were improved. The cycling results point out the less over-potential and resistance at the cathode/electrolyte interface. These improvements are studied by SEM, EIS and XPS techniques. PMID:25760031

  18. Evaluations of frequency shift and stability in rubidium vapor stabilized semiconductor lasers.

    PubMed

    Furuta, H; Ohtsu, M

    1989-09-01

    Laser frequencies were stabilized to the linear and saturated absorption spectral lines(LAS, SAS) in (87)Rb vapors which were filled into two kinds of glass cell: cell A ((87)Rb vapor only) and cell B ((87)Rb vapor and buffer gases). The frequency shifts induced by the change of laser power density were -5 MHz/(mW/cm(2)) and - 10 MHz/(mW/cm(2)) for cells A and B, respectively, when LAS was used. A frequency shift of -0.8 MHz/K was observed for cell B, which underwent a temperature change. However, such a temperature-induced shift was not observed for cell A. The highest frequency stability was 7.7 x 10(-11) at a 70-s integration time. PMID:20555766

  19. Evaluations of frequency shift and stability in rubidium vapor stabilized semiconductor lasers

    SciTech Connect

    Furuta, H.; Ohtsu, M. )

    1989-09-01

    Laser frequencies were stabilized to the linear and saturated absorption spectral lines(LAS, SAS) in {sup 87}Rb vapors which were filled into two kinds of glass cell: cell A ({sup 87}Rb vapor only) and cell B ({sup 87}Rb vapor and buffer gases). The frequency shifts induced by the change of laser power density were {minus}5 MHz/(mW/cm{sup 2}) and {minus}10 MHz/(mW/cm{sup 2}) for cells A and B, respectively, when LAS was used. A frequency shift of {minus}0.8 MHz/K was observed for cell B, which underwent a temperature change. However, such a temperature-induced shift was not observed for cell A. The highest frequency stability was 7.7 {times} 10{sup {minus}11} at a 70-s integration time.

  20. Development and flight evaluation of an augmented stability active controls concept with a small tail

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Parasite drag reduction evaluation is composed of wind tunnel tests with a standard L-1011 tail and two reduced area tail configurations. Trim drag reduction is evaluated by rebalancing the airplane for relaxed static stability. This is accomplished by pumping water to tanks in the forward and aft of the airplane to acheive desired center of gravity location. Also, the L-1011 is modified to incorporate term and advanced augmented systems. By using advanced wings and aircraft relaxed static stability significant fuel savings can be realized. An airplane's dynamic stability becomes more sensitive for decreased tail size, relaxed static stability, and advanced wing configurations. Active control pitch augmentation will be used to acheive the required handling qualities. Flight tests will be performed to evaluate the pitch augmentation systems. The effect of elevator downrig on stabilizer/elevator hinge moments will be measured. For control system analysis, the normal acceleration feedback and pitch rate feedback are analyzed.

  1. Evaluation of the physical stability of two oleogels.

    PubMed

    Almeida, Isabel F; Bahia, M Fernanda

    2006-12-11

    Oleogels are semisolid systems obtained with an organogelator and a hydrophobic liquid that have been investigated over the past few years and that could play an important role as dermatological bases. Recently, we have developed an oleogel of sorbitan monostearate (19wt.%) and sweet almond oil (SM-SAO) and another one of cholesterol (3.5wt.%) and liquid paraffin (Ch-LP). The aim of this work is to access their physical stability using three different methodologies. The gels were stored at different temperatures (20 and 40 degrees C) over a 3-month period. Appearance and textural properties were assessed on each month. An accelerated test was also performed where the temperature changed between 4 and 40 degrees C every 24h, during 7 days. Rheological tests were also carried out as they could provide useful elements to predict stability. The gels were quite stable at 20 degrees C, being the SM-SAO gel the most stable. The textural properties of both gels were influenced by temperature. The decrease of the textural parameters, observed after storage at 40 degrees C and in the cycling test, was more significant for the SM-SAO gel. A good correlation was found between rheological analysis and conventional stability tests. The heating/cooling cycle test provided useful information in a short period of time. PMID:16996708

  2. TECHNOLOGY EVALUATION REPORT: SILICATE TECHNOLOGY CORPORATION - SOLIDIFICATION/STABILIZATION OF PCP AND INORGANIC CONTAMINANTS IN SOILS - SELMA, CA

    EPA Science Inventory

    This Technolgy Evaluation Report evaluates the solidification/stabilization process of Silicate Technology Corporation (STC) for the on-site treatment of contaminated soil The STC immobilization technology uses a proprietary product (FMS Silicate) to chemically stabilize and ...

  3. Dynamic simulation of voltage collapses

    SciTech Connect

    Deuse, J.; Stubbe, M. )

    1993-08-01

    Most of the time the voltage collapse phenomena are studied by means of computer programs designed for the calculation of steady state conditions. But in the real world, the simultaneous occurrences of losses of synchronism, of AVR dynamics or of transformer tap changes call for a full dynamic simulation of voltage phenomena. The present paper shows some examples of dynamic simulations of voltage phenomena using a new general purpose stability program (EUROSTAG), covering in a continuous way the classical fields of transient, mid-term and long-term stability, and also the quasi steady state conditions of a power system.

  4. Comprehensive Stability Evaluation of Rock Slope Using the Cloud Model-Based Approach

    NASA Astrophysics Data System (ADS)

    Liu, Zaobao; Shao, Jianfu; Xu, Weiya; Xu, Fei

    2014-11-01

    This article presents the cloud model-based approach for comprehensive stability evaluation of complicated rock slopes of hydroelectric stations in mountainous area. This approach is based on membership cloud models which can account for randomness and fuzziness in slope stability evaluation. The slope stability is affected by various factors and each of which is ranked into five grades. The ranking factors are sorted into four categories. The ranking system of slope stability is introduced and then the membership cloud models are applied to analyze each ranking factor for generating cloud memberships. Afterwards, the obtained cloud memberships are synthesized with the factor weights given by experts for comprehensive stability evaluation of rock slopes. The proposed approach is used for the stability evaluation of the left abutment slope in Jinping 1 Hydropower Station. It is shown that the cloud model-based strategy can well consider the effects of each ranking factor and therefore is feasible and reliable for comprehensive stability evaluation of rock slopes.

  5. Evaluation of degradation kinetics and physicochemical stability of tenofovir.

    PubMed

    Agrahari, Vivek; Putty, Sandeep; Mathes, Christiane; Murowchick, James B; Youan, Bi-Botti C

    2015-03-01

    Tenofovir (TFV) has been proven to prevent the transmission of the Human Immunodeficiency Virus (HIV) through the vagina. But, there is little information available about its stability under various storage and stress conditions. Hence, this study aimed to investigate the degradation behavior and physicochemical stability of TFV using liquid chromatography coupled mass spectrometry (LC-MS) and solid state X-ray diffraction (XRD) analyses. The LC-MS analysis was performed on a QTrap mass spectrometer with an enhanced mass spectrum (EMS) scan in positive mode. A reversed phase C18 column was used as the stationary phase. TFV exhibited degradation under acidic and alkaline hydrolytic conditions. The degradation products with m/z 289.2 and 170 amu have been proposed as 6-Hydroxy adenine derivative of TFV, and (2-hydroxypropan-2-yloxy) methylphosphonic acid, respectively. A pseudo-first-order degradation kinetic allowed for estimating the shelf-life, half-life, and time required for 90% degradation of 3.84, 25.34, and 84.22 h in acidic conditions, and 58.26, 384.49, and 1277.75 h in alkaline conditions, respectively. No significant degradation was observed at pH 4.5 (normal cervicovaginal pH) and oxidative stress conditions of 3% and 30% v/v hydrogen peroxide solutions. The shelf life of TFV powder at room temperature was 23 months as calculated by using an Arrhenius plot. The XRD pattern showed that the drug was stable and maintained its original crystallinity under the accelerated and thermal stress conditions applied. Stability analyses revealed that the TFV was stable in various stress conditions; however, formulation strategies should be implemented to protect it in strong acidic and alkaline environments. PMID:24817173

  6. EVALUATION OF CHEMICALLY BONDED PHOSPHATE CERAMICS FOR MERCURY STABILIZATION OF A MIXED SYNTHETIC WASTE

    EPA Science Inventory

    This experimental study was conducted to evaluate the stabilization and encapsulation technique developed by Argonne National Laboratory, called the Chemically Bonded Phosphate Ceramics technology for Hg- and HgCl2-contaminated synthetic waste materials. Leachability ...

  7. EVALUATION USING AN ORGANOPHILIC CLAY TO CHEMICALLY STABILIZE WASTE CONTAINING ORGANIC COMPOUNDS

    EPA Science Inventory

    A modified clay (organophilic) was utilized to evaluate the potential for chemically stabilizing a waste containing organic compounds. hemical bonding between the binder and the contaminants was indicated. eachate testing also indicated strong binding. Copy available at NTIS as ...

  8. Technical evaluation of the proposed design modifications and technical specification changes on grid voltage degradation (Part A) for the Pilgrim Nuclear Power Station, Unit 1

    SciTech Connect

    White, R.L.

    1980-01-01

    This report documents the technical evaluation of the proposed design modifications and Technical Specification changes for protection of Class 1E equipment from grid voltage degradation for the Pilgrim Nuclear Power Station. The review criteria are based on several IEEE standards and the Code of Federal Regulations. The evaluation compares the submittals made by the licensee with the NRC staff positions and the review criteria and presents the reviewer's conclusion on the acceptability of the proposed system.

  9. Evaluation of primary stability of inclined orthodontic mini-implants.

    PubMed

    Inaba, Mizuki

    2009-09-01

    The aim of this study was to investigate the initial stability of mini-implants when placed slanting or perpendicular to the bone surface, and to examine the effects of differences in tractional direction. Titanium mini-implants were inserted into rabbit nasal bones, slanting (60 degrees , 120 degrees ) or perpendicular (90 degrees ) to the bone surface. These implants were then loaded with a force of approximately 2 N, using a NiTi coil spring. The mobilities on the traction and non-traction sides were assessed using the Periotest device immediately after placement and after traction for two weeks. Then, the tissues with the mini-implants were resected, and the contact between the bone and the implant was examined by electron microscopy. There was a tendency for the mobilities of the mini-implants at 60 degrees and 120 degrees to be smaller than those at 90 degrees when measured before and after traction. The bone-implant contact lengths at 60 degrees were significantly longer than those at 90 degrees . There was no significant difference in the bone-implant contact ratio among the different angles. Correlations were evident between implant mobility and contact length or contact ratio. It is concluded that in clinical practice, implants inclined to the bone surface tend to have better primary stability. PMID:19776501

  10. Evaluation of skeletal stability following surgical correction of mandibular prognathism.

    PubMed

    Ayoub, A F; Millett, D T; Hasan, S

    2000-08-01

    This retrospective study was designed to assess skeletal stability after the correction of mandibular prognathism by sagittal split osteotomy (SSO) and intraoral vertical subsigmoid osteotomy (VSO). We used lateral cephalographs of 31 patients taken before, immediately after, and at least one year after the operation. We recorded euclidean distance matrix analysis, linear and angular measurements, and x and y co-ordinates of cephalometric landmarks for each cephalograph. There were no significant differences in extent of the mandibular retrognathia or magnitude of change between the two groups. The main significant changes in both groups were reduction of the total mandibular length, and posterior shifting in the mandible. One year after the operation the main change was the mean forward relapse of 2.5 mm in the SSO group and the mean posterior relapse of 0.5 mm in the VSO group. The difference in skeletal stability between the groups was significant (P< 0.05), and we conclude that VSO is the more effective technique for correcting mandibular prognathism. PMID:10922156

  11. Evaluation of oxygen utilization as an indicator of municipal solid-waste compost stability

    SciTech Connect

    Zimmerman, R.A.

    1991-01-01

    This research evaluated oxygen utilization parameters as indicators of MSW compost stability. Parameters evaluated were the oxygen utilization rate (OUR), specific oxygen uptake rate (SOUR), five-day biochemical oxygen demand, and chemical oxygen demand. In addition, other suggested indicators of stability were investigated including percent volatile solids, volatile solids reduction, nitrogen content, carbon: nitrogen ratio, and reheating potential (RP). OUR is a measure of the rate of oxygen utilization by the microorganisms in the decomposition of organic matter in compost. OUR was observed to be sensitive to the degree of stabilization and decreased with increasing compost age and stability. OUR values near zero indicate that the compost microorganisms are in a state of endogenous respiration, which is characteristic of a stable compost. Therefore, OUR is an excellent indicator of stability. A number of disadvantages are associated with OUR for practical application. Therefore, other parameters were evaluated as indicators of stability based on their statistical correlation to OUR. RP exhibited the strongest correlation to OUR. In combination, RP and SOUR were the two parameters which exhibited the strongest correlation to OUR. OUR, RP, and SOUR are all measures of microbial activity which reflect the degree of organic decomposition, and therefore, stability. Based on the results of this research; OUR, RP, and SOUR are useful parameters in assessing compost stability.

  12. Recommendations for the evaluation of specimen stability for flow cytometric testing during drug development.

    PubMed

    Brown, Lynette; Green, Cherie L; Jones, Nicholas; Stewart, Jennifer J; Fraser, Stephanie; Howell, Kathy; Xu, Yuanxin; Hill, Carla G; Wiwi, Christopher A; White, Wendy I; O'Brien, Peter J; Litwin, Virginia

    2015-03-01

    The objective of this manuscript is to present an approach for evaluating specimen stability for flow cytometric methods used during drug development. While this approach specifically addresses stability assessment for assays to be used in clinical trials with centralized testing facilities, the concepts can be applied to any stability assessment for flow cytometric methods. The proposed approach is implemented during assay development and optimization, and includes suggestions for designing a stability assessment plan, data evaluation and acceptance criteria. Given that no single solution will be applicable in all scenarios, this manuscript offers the reader a roadmap for stability assessment and is intended to guide the investigator during both the method development phase and in the experimental design of the validation plan. PMID:25662815

  13. Evaluating the cement stabilization of arsenic-bearing iron wastes from drinking water treatment.

    PubMed

    Clancy, Tara M; Snyder, Kathryn V; Reddy, Raghav; Lanzirotti, Antonio; Amrose, Susan E; Raskin, Lutgarde; Hayes, Kim F

    2015-12-30

    Cement stabilization of arsenic-bearing wastes is recommended to limit arsenic release from wastes following disposal. Such stabilization has been demonstrated to reduce the arsenic concentration in the Toxicity Characteristic Leaching Procedure (TCLP), which regulates landfill disposal of arsenic waste. However, few studies have evaluated leaching from actual wastes under conditions similar to ultimate disposal environments. In this study, land disposal in areas where flooding is likely was simulated to test arsenic release from cement stabilized arsenic-bearing iron oxide wastes. After 406 days submersed in chemically simulated rainwater, <0.4% of total arsenic was leached, which was comparable to the amount leached during the TCLP (<0.3%). Short-term (18 h) modified TCLP tests (pH 3-12) found that cement stabilization lowered arsenic leaching at high pH, but increased leaching at pH<4.2 compared to non-stabilized wastes. Presenting the first characterization of cement stabilized waste using μXRF, these results revealed the majority of arsenic in cement stabilized waste remained associated with iron. This distribution of arsenic differed from previous observations of calcium-arsenic solid phases when arsenic salts were stabilized with cement, illustrating that the initial waste form influences the stabilized form. Overall, cement stabilization is effective for arsenic-bearing wastes when acidic conditions can be avoided. PMID:26247378

  14. Real World Crash Evaluation of Vehicle Stability Control (VSC) Technology

    PubMed Central

    Bahouth, G.

    2005-01-01

    This study quantifies the effect of Vehicle Stability Control (VSC) in reducing crash involvement rates for a subset of vehicles in the US fleet. Crash rates for a variety of impact types before and after VSC technology was implemented are compared. Police-reported crashes from six available US state files from 19982002 were analyzed including 13,987 crash-involved study vehicles not equipped with the technology and 5,671 crashes of vehicles equipped with VSC as a standard feature. Overall, an 11.2% (95% CI: 2.4%, 21.1%) reduction in multi-vehicle frontal crash involvement was identified for VSC-equipped vehicles. A 52.6% (95% CI: 42.5%, 62.7%) reduction in single-vehicle crash rates was found. PMID:16179137

  15. High Voltage TAL Performance

    NASA Technical Reports Server (NTRS)

    Jacobson, David T.; Jankovsky, Robert S.; Rawlin, Vincent K.; Manzella, David H.

    2001-01-01

    The performance of a two-stage, anode layer Hall thruster was evaluated. Experiments were conducted in single and two-stage configurations. In single-stage configuration, the thruster was operated with discharge voltages ranging from 300 to 1700 V. Discharge specific impulses ranged from 1630 to 4140 sec. Thruster investigations were conducted with input power ranging from 1 to 8.7 kW, corresponding to power throttling of nearly 9: 1. An extensive two-stage performance map was generated. Data taken with total voltage (sum of discharge and accelerating voltage) constant revealed a decrease in thruster efficiency as the discharge voltage was increased. Anode specific impulse values were comparable in the single and two-stage configurations showing no strong advantage for two-stage operation.

  16. Evaluation of properties and storage stability of Madhuca indica biodiesel.

    PubMed

    Kapilan, N; Ashok Babu, T P; Reddy, R P

    2009-01-01

    Mahua Oil (MO) is an underutilized non-edible vegetable oil, which is available in large quantities in India. In the present work, biodiesel was derived from the MO by the transesterification process. The fuel properties of the MO biodiesel were found to be within the limits of biodiesel specifications of many countries. The chemical nature of biodiesel makes it more susceptible to oxidation during long-term storage which leads to degradation of fuel properties that can compromise fuel quality. The effect of long storage condition on the stability of the MO biodiesel was studied in the present work. The biodiesel samples were stored in plastic containers at room temperature. The study was conducted for a period of 12 months and the test sample was kept in the darkness. From the experimental results, it was observed that the acid value and viscosity increases with the storage time, but the iodine value decreased with increasing storage time. This is due to the presence of the double bond in the molecule of the biodiesel which produce a high level of reactivity. This high level reactivity produces formation of hydroperoxides, soluble polymers and other secondary products. From the experimental results, a slight difference in the acid value, iodine value and viscosity of the MO biodiesel stored for a period of 30 days was observed. But after this period, the differences were significant. PMID:19915318

  17. Enhanced analogue front-end for the measurement of the high state of wide-band voltage pulses with 87 dB common-mode rejection ratio and 0.65 ppm 1-day offset stability.

    PubMed

    Arpaia, Pasquale; Baccigalupi, Carlo; Martino, Michele

    2015-09-01

    An improved analogue front-end for measuring the high state of trapezoidal voltage pulses with transition duration of 3 ?s is presented. A new measurement system, composed by a front-end and the state-of-the-art acquisition board NI PXI-5922, has been realized with improved Common Mode Rejection Ratio (CMRR) of more than 87 dB at DC and 3-sigma stability of 0.65 ppm over 1 day. After highlighting the main design enhancements with respect to state-of-the-art solutions, the CMRR measurement is reported. The output drift due to temperature and humidity is assessed to be negligible. Finally, the worst-case repeatability is measured both with shorted-to-ground inputs and with an applied common-mode voltage of 10 V, which represents the nominal working condition. PMID:26429481

  18. Operating stability of a self-breakdown spark-gap frequency switch rated at a voltage of 300 kV and a switched power of up to 450 J

    NASA Astrophysics Data System (ADS)

    Koval'chuk, B. M.; Korolev, Yu. D.; Kumpyak, E. V.; Frants, O. B.; Shemyakin, I. A.

    2014-12-01

    A test bench for studying two-electrode spark gaps rated at a voltage of 300 kV and a pulse repetition rate of up to 10 Hz and operating in air at elevated pressure. The typical time of pulse charging of a capacitive storage in the bench equals about 100 μs. The object of investigation is a spark gap the operating stability of which at a level of 10% of the rate voltage is achieved by initiating a corona discharge at the prebreakdown stage. It is shown that unstable operation is due to the accumulation of nitrogen oxides in the gap. To maintain the oxide content at an acceptable level, continuous gas purging is applied and necessary gas flow rates are estimated.

  19. Temporary anchorage device stability: an evaluation of thread shape factor.

    PubMed

    Migliorati, M; Signori, A; Silvestrini-Biavati, A

    2012-10-01

    The resistance to extraction of temporary anchorage devices (TADs) depends on various factors, including miniscrew design, shear strength, and bone density. This research introduces the thread shape factor (TSF) as a new factor for the evaluation of TAD mechanical properties. The authors evaluated three TADs for a total of 27 tests: Mini-impianto autoforante (Leone, 1.75 mm diameter and 8 mm length), Orthoscrew (Leader Ortodonzia, 1.65 mm diameter and 9 mm length), and MAS (Miniscrew Anchorage System, 1.3 mm diameter and 11 mm length). For each TAD, the images were acquired via a 20.00 kV scanning electron microscopy to measure their respective mean depth of thread (D), pitch (P), and the relationship between the two (TSF). Subsequently, pullout tests on organic bone analogue were carried out using a testing machine; a crosshead speed of 2 mm/minutes was applied. A two-way analysis of variance was performed to evaluate the interaction between the type of miniscrew and the cortical thickness. A post hoc analysis for single comparisons was subsequently employed. In addition, if homogeneity of variances was not rejected, Scheff's test was performed, while Tamhane's test was carried out if the homogeneity of variance assumption was not met. Univariate linear regression models were fitted to evaluate the relationship between the outcomes and TSF, D, and P separately. A P value of 0.05 was considered statistically significant. From univariate linear regression, TSF, D, and P were statistically significant predictors of 'peak load'. The tests showed that TSF has a statistical significance for describing the mechanical competency of TADs. PMID:21367816

  20. A perspective on coatings to stabilize high-voltage cathodes: LiMn1.5Ni0.5O4 with subnanometer Lipon cycled with LiPF6 electrolyte

    SciTech Connect

    Kim, Yoongu; Dudney, Nancy J; Chi, Miaofang; Martha, Surendra K; Nanda, Jagjit; Veith, Gabriel M; Liang, Chengdu

    2013-01-01

    High voltage Li-ion cathodes push the limits of stability for both cathode and electrolyte. Here subnanometer coatings of an amorphous thin film electrolyte (Lipon) improved the room temperature and 60 C cycling stability of a LiMn1.5Ni0.5O4 spinel cathode when charged to 4.9V with a standard LiPF6 carbonate electrolyte. The cathodes delivered superior C-rate performances up to a 5C discharge, when compared to the uncoated cathodes. Enhanced performance extended for at least 100 cycles. Electrochemical impedance spectroscopy indicates that Lipon slows the increase of interface resistance. Thicker 1-3nm Lipon coatings are sufficiently insulating as to block electronic transport to the cathode particles. Thick coatings also slow Mn dissolution. Results suggest that Lipon may act to scavenge impurities or block active sites that promote electrolyte decomposition. While greatly improved by the Lipon coating, this cathode is not sufficiently stable for long cycle life applications. Further work is needed to assess if and what surface coatings will ultimately stabilize the high voltage cathodes. Comments include insight from other studies of Lipon coated cathodes and directions for future research.

  1. Evaluating Marie Byrd Land stability using an improved basal topography

    NASA Astrophysics Data System (ADS)

    Holschuh, N.; Pollard, D.; Alley, R. B.; Anandakrishnan, S.

    2014-12-01

    Prior understanding of the ice-sheet setting in Marie Byrd Land (MBL) was derived primarily from geologic and geochemical studies of the current nunataks, with very few geophysical surveys imaging the ice covered regions. The geologic context suggested that the ice rests on a broad regional high, in contrast to the deep basins and trenches that characterize the majority of West Antarctica. This assumed topography would favor long-term stability for the West Antarctic Ice Sheet (WAIS) in MBL. Airborne geophysical data collected in 2009 reveal a much deeper bed than previously estimated, including a significant trough underlying DeVicq Glacier and evidence for extensive glacial erosion. Using these data, we produce a new map of subglacial topography, with which we model the sensitivity of WAIS to a warming ocean using the ice-sheet model of Pollard and DeConto (2012b). We compare the results to estimates of ice loss during WAIS collapse using the previously defined subglacial topography, to determine the impact of the newly discovered subglacial features. Our results indicate that the topographic changes are not sufficient to destabilize the northern margin of MBL currently feeding the Getz Ice Shelf; the majority of ice loss occurs from flow toward the Siple Coast. However, despite only slight dynamic differences, using the new bed as a boundary condition results in an additional 8 cm of sea-level rise during major glacial retreat, an increase of just over 2%. Precise estimation of past and future ice retreat, as well as a complete understanding of the geologic history of the region, will require a higher resolution picture of the bed topography around the Executive Committee mountains.

  2. Bench-Scale Evaluation Of Chemically Bonded Phosphate Ceramic Technology To Stabilize Mercury Waste Mixtures

    EPA Science Inventory

    This bench-scale study was conducted to evaluate the stabilization of mercury (Hg) and mercuric chloride-containing surrogate test materials by the chemically bonded phosphate ceramics technology. This study was performed as part of a U.S. EPA program to evaluate treatment and d...

  3. Extended performance solar electric propulsion thrust system study. Volume 5. Capacitor-diode voltage multiplier: Technology evaluation

    NASA Technical Reports Server (NTRS)

    Martinelli, R. M.

    1977-01-01

    A 1-kW capacitor-diode voltage multiplier (CDVM) was designed, fabricated and tested to demonstrate the power of feasibility of high power CDVM's and to verify the analytical techniques that had been used to predict the performance characteristics of a 6-kw CDVM. High efficiency (96.2%), a low ratio of component weight to power (0.55 kg/kW), and low output ripple voltage (less than 1%, peak to peak) were obtained during the operation of a 1-kW CDVM various input line, load current, and load fault conditions.

  4. Evaluation, repair and stabilization of the boling sinkhole

    NASA Astrophysics Data System (ADS)

    Dreyer, Boyd V.; Schulz, Clyde E.

    1986-03-01

    Abrupt ground subsidence occurred along FM 442, approximately 3 miles east of Boling, in Wharton County, Texas, in August 1983 The subsidence created a depression of approximately 250 feet in diameter with a maximum depth of about 25 feet. Roadway collapse, pavement breakage, and inundation of the sinkhole by subsurface waters forced the closure of FM 442 to thru-traffic The vicinity of the sinkhole is underlain, by alluvial deposits of the Colorado River drainage basin and unconsolidated Miocene, Pliocene, and Pleistocene sediments to a depth of about 500 feet. The sediments consist largely of sand, silts, clays, and gravels. The Boling Salt Dome and its associated caprock occur directly beneath the section of unconsolidated sediments Major and minor axes of the dome are about 5 miles and 35 miles, respectively, and the sinkhole occurred approximately 1 mile east-northeast of the dome's center An investigation was conducted in the immediate area of the sinkhole to determine the cause of the subsidence and also to determine the feasibility of dewatering the sinkhole Four monitoring wells were installed around the perimeter to evaluate the potential recharge from shallow sand units Two 300-foot holes were drilled and geophysically logged to determine the stratigraphy adjacent to the sinkhole, and two slope indicators were installed in order to evaluate further earth movements A total of six million gallons of saline water were removed and disposed of from the sinkhole Based on information provided by the geologic and dewatering investigation, the Texas State Department of Highways and Public Transportation elected to fill the existing sinkhole and reconstruct the roadway A total of 3,500 cubic yards of rock borrow and 26,000 cubic yards of soil borrow were placed in the depression Construction began in February 1984, and the roadway was completed in May A monitoring program to evaluate subsequent earth movements will continue into 1985

  5. Myopia Stabilization and Associated Factors Among Participants in the Correction of Myopia Evaluation Trial (COMET)

    PubMed Central

    2013-01-01

    Purpose. To use the Gompertz function to estimate the age and the amount of myopia at stabilization and to evaluate associated factors in the Correction of Myopia Evaluation Trial (COMET) cohort, a large ethnically diverse group of myopic children. Methods. The COMET enrolled 469 ethnically diverse children aged 6 to younger than 12 years with spherical equivalent refraction between ?1.25 and ?4.50 diopters (D). Noncycloplegic refraction was measured semiannually for 4 years and annually thereafter. Right eye data were fit to individual Gompertz functions in participants with at least 6 years of follow-up and at least seven refraction measurements over 11 years. Function parameters were estimated using a nonlinear least squares procedure. Associated factors were evaluated using linear regression. Results. In total, 426 participants (91%) had valid Gompertz curve fits. The mean (SD) age at myopia stabilization was 15.61 (4.17) years, and the mean (SD) amount of myopia at stabilization was ?4.87 (2.01) D. Ethnicity (P < 0.0001) but not sex or the number of myopic parents was associated with the age at stabilization. Ethnicity (P = 0.02) and the number of myopic parents (P = 0.01) but not sex were associated with myopia magnitude at stabilization. At stabilization, African Americans were youngest (mean age, 13.82 years) and had the least myopia (mean, ?4.36 D). Participants with two versus no myopic parents had approximately 1.00 D more myopia at stabilization. The age and the amount of myopia at stabilization were correlated (r = ?0.60, P < 0.0001). Conclusions. The Gompertz function provides estimates of the age and the amount of myopia at stabilization in an ethnically diverse cohort. These findings should provide guidance on the time course of myopia and on decisions regarding the type and timing of interventions. PMID:24159085

  6. Stability of trimethyl phosphate non-flammable based electrolyte on the high voltage cathode (LiNi0.5Mn1.5O4)

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kazuaki; Martinez, Mathieu; Gutel, Thibaut; Mailley, Sophie; De vito, Eric; Patoux, Sbastien; Inoue, Kazuhiko; Utsugi, Koji

    2015-01-01

    Trimethyl phosphate (TMP) which is a non-flammable solvent is a good candidate to replace flammable carbonates in battery electrolytes. In the case of Li-ion battery using high voltage cathode such as LiNi0.5Mn1.5O4 (LNM), the use of TMP based electrolyte leads to high cycle performance (96% capacity retention after 50 cycles). Also gas generation drastically decreased. According to careful observation of the LNM surface by scanning electron microscopy (SEM) after cycles, it has been found that TMP decomposes itself and forms polymer based film on the electrode surface suppressing further electrolyte decomposition. This work leads us to propose new electrolytes for Li-ion batteries using high voltage cathode.

  7. Voltage clamp simulation.

    PubMed

    Kootsey, J M

    1975-04-01

    The voltage clamp experiment on the squid giant axon is successful because of the special characteristics of the preparation: cylindrical shape, large diameter, and so on. The method is much more difficult to apply to small cells and to networks of cells because voltage gradients and unwanted stray impedances are not readily eliminated. Simulation of the voltage clamp experiment is proposed as a method for determining when these factors and the characteristics of the clamp electronics affect the experimental results, for evaluating experimental techniques for improving the quality of the clamp, and as a possible method of learning something about the membrane when no experimental improvement is feasible. The numerical methods for including one spatial variable in the analysis are reviewed briefly. Several examples of voltage clamp simulations are discussed: double sucrose gap clamp of axons, clamp of the giant synapse, single sucrose gap clamp of cardiac muscle bundles, point clamp of the end of a fiber bundle, and the steady-state three-microelectrode clamp of a cable with nonlinear membrane. The results indicate that the quality of a clamp cannot be evaluated from the voltage and current records as commonly measured. PMID:1123090

  8. Neuromuscular evaluation of post-orthodontic stability: an experimental protocol.

    PubMed

    Ferrario, Virgilio F; Marciandi, Paolo V; Tartaglia, Gianluca M; Dellavia, Claudia; Sforza, Chiarella

    2002-01-01

    To prevent relapse after orthodontic treatment, retention is often considered indispensable. Soft tissues are thought to have a significant influence on dental movements. To quantify the influence of masticatory muscles on post-treatment relapse, and in an attempt to avoid unnecessary procedures, 2 male orthodontic patients (13 and 30 years old at debonding) were followed up. The patients completed 2 years of fixed orthodontic treatment and received no post-orthodontic retention. After 1 week and again after 6 months, alginate impressions of dental arches and a surface electromyographic (EMG) assessment of the masseter and temporalis muscles during maximum voluntary clenching were performed. The younger patient received surface EMG monitoring once a month for the first 6 months and at the 1-year follow-up appointment. Arch dimensions and the 3-dimensional inclination of the facial axis of the clinical crown (FACC) were measured using a computerized digitizer. Symmetry in muscular contraction was measured by the percentage overlapping coefficient (POC), and potential lateral displacing components were assessed by the torque coefficient (TC). At the 6-month follow-up, no clinical modifications were observed. Quantitative evaluation assessed that arch dimensions had changed slightly (up to 1 mm). While the adolescent patient had no modifications in FACC inclinations, the 30-year-old patient showed significant alterations (up to 18 degrees). In all examinations of the adolescent patient, POC was higher than 86% and TC was lower than 10%. In the adult, POC was inside the normal range, while all TCs were higher than 10.5%. The larger TC measured in the adult may explain the larger modifications in the 3-dimensional position of his dental crowns. In conclusion, a surface EMG assessment may help in the detection of patients who might need post-orthodontic retention. PMID:12596694

  9. Evaluation of higher distribution and/or utilization voltages. Third interim report (October 1979): analysis of individual component cost and/or energy efficiencies

    SciTech Connect

    Not Available

    1981-04-01

    This interim report provides documentation on the third task, Analysis of Individual Component Cost and/or Energy Efficiencies, of DOE Contract No. ET-78-C-01-2866, Evaluation of Higher Distribution and/or Utilization Voltages. The work performed under this task includes the development of both cost and energy loss models for the distribution and customer utilization system elements as well as the analysis of critical performance variables for the types of motors in end use elements, as a function of voltage level. The purpose of this task is to provide individual component cost and energy models which will be incorporated in the global system optimization program under Task 4. A major output of this task is a mathematical model for each component's cost and/or energy losses and a graphical representation of each model.

  10. Improved cycle stability and high-rate capability of Li3VO4-coated Li[Ni0.5Co0.2Mn0.3]O2 cathode material under different voltages

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Jin, Feng-Min; Chen, Fang-Jie; Chen, Li

    2014-06-01

    Li3VO4-coated Li[Ni0.5Co0.2Mn0.3]O2 cathode material exhibits much better cycling stability, rate capability, and high voltage cycling behavior than pristine Li[Ni0.5Co0.2Mn0.3]O2 at room temperature. The sample coated with 3 wt.% Li3VO4 shows the optimum electrochemical performance. It delivers a capacity of 61.5 mAh g-1 at 10 C (1800 mA g-1) after 100 cycles. The capacity retention at 1 C (180 mA g-1) is 63.5% at cut-off voltage 4.6 V, and 63.0% at a higher cut-off voltage 4.8 V. XRD and XPS results reveal that the Li3VO4 coating layer reinforces the surface of matrix material, which benefits structural stability of Li[Ni0.5Co0.2Mn0.3]O2 during long-term cycling. CV and EIS tests indicate that the improvement of electrochemical performances could be attributed to higher Li+ conductivity, suppression of Co and Mn dissolution from Li[Ni0.5Co0.2Mn0.3]O2, and decreased polarization during cycling since Li3VO4 layer on Li[Ni0.5Co0.2Mn0.3]O2 surface acts as a relatively stable protective barrier as well as an excellent Li-ion conductor.

  11. Technical-evaluation report on the adequacy of station electric-distribution-system voltages for the Prairie Island Nuclear Generating Plant, Units 1 and 2. (Docket Nos. 50-282, 50-306)

    SciTech Connect

    Selan, J C

    1982-09-17

    This report documents the technical evaluation of the adequacy of the station electric distribution system voltages for the Prairie Island Nuclear Generating Plant, Units 1 and 2. The evaluation is to determine if the onsite distribution system in conjunction with the offsite power sources has sufficient capacity to automatically start and operate all Class 1E loads within the equipment voltage ratings under certain conditions established by the Nuclear Regulatory Commission. The evaluation finds that with some minor transformer loading modifications, hardware changes and the results of equipment testing and manufacturer data, the offsite sources were demonstrated to supply adequate voltage to the Class 1E equipment under worst case conditions.

  12. An integrated chemical, thermal, and microbiological approach to compost stability evaluation.

    PubMed

    Mondini, Claudio; Dell'Abate, Maria Teresa; Leita, Liviana; Benedetti, Anna

    2003-01-01

    The evaluation of compost stability is of the utmost importance for the reliability of composting as a recycling strategy. To date there is no single parameter that can give a sure indication of the stability of composts from different starting materials. This paper investigates different methods of evaluating the dynamics of transformation of materials and the stability level of the end products in a composting process. The following parameters were determined on compost samples of different ages from cotton (Gossypium herbaceum L.) cardings and yard wastes: humification index (HI), degree of humification (DH), thermogravimetry (TG) microbial biomass C (B(C)), and ninhydrin-reactive N (B(NIN)). Finally, from TG, derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) thermal stability parameters were deduced. Humification parameters in the end products (0.2 and 81% for HI and DH, respectively) showed the effective stability reached by the organic matter (OM). Thermal analysis evidenced the presence of two main organic pools with different thermal stability. During composting a relative increase in the more stable organic pool was indicated by the variation of the thermostability index R1 from 0.41 to 0.74. The parameter R1 was significantly correlated with both HI (r = -0.94; P < 0.05) and DH (r = 0.97; P < 0.05). Microbial biomass content dynamics reflected the availability of readily decomposable substrates. The ratio between B(NIN) and total N in the end product was 0.96%, indicating a good stability level. The simultaneous application of different approaches, considering different properties of composting materials, provides a more complete description of the stability and quality reached by the organic materials. PMID:14674563

  13. Solid state high-voltage pulser operates with low supply voltage

    NASA Technical Reports Server (NTRS)

    Milberger, W. E.

    1968-01-01

    High speed klystron cathode pulser requires low voltage to generate high-voltage pulses. Broadband video transformers are wound in two configurations - /1/ transmission line, multifilar toroids and /2/ loop coupling toroids. The circuit adapts to generate high-speed, high-voltage, high-stability power pulses at megawatt levels.

  14. TECHNOLOGY EVALUATION REPORT: CHEMFIX TECHNOLOGIES, INC. - SOLIDIFICATION/STABILIZATION PROCESS - CLACKAMAS, OREGON - VOLUME I

    EPA Science Inventory

    The CHEMFIX solidification/stabilization process was evaluated in the U.S. Environment Protection Agency's SITE program. Waste from an uncontrolled hazardous waste site was treated by the CHEMFIX process and subjected to a variety of physical and chemical test methods. Physical t...

  15. TECHNOLOGY EVALUATION REPORT: CHEMFIX TECHNOLOGIES, INC. - SOLIDIFICATION/STABILIZATION PROCESS - CLACKAMAS, OREGON - VOLUME II

    EPA Science Inventory

    The CHEMFIX solidification/stabilization process was evaluated in the U.S. Environmental Protection Agency's SITE program. Waste from an uncontrolled hazardous waste site was treated by the CHEMFIX process and subjected to a variety of physical and chemical test methods. Physical...

  16. EVALUATION OF THE THERMAL STABILITY POHC INCINERABILITY RANKING IN A PILOT-SCALE ROTARY KILN INCINERATOR

    EPA Science Inventory

    A series of pilot-scale incineration tests was performed at EPA's Incineration Research Facility to evaluate the thermal stability-based POHC incinerability ranking. In the tests, mixtures of 12 P0HCs with predicted incinerability spanning the range af most to least difficult to ...

  17. PILOT-SCALE EVALUATION OF THE THERMAL STABILITY POHC INCINERABILITY RANKING

    EPA Science Inventory

    A test series were performed at the U.S. EPA Incineration Research Facility (IRF) to evaluate the thermal-stability-based principal organic hazardous constituent (POHC) incinerability ranking. ixtures of twelve POHCs with predicted incinerabilities spanning the range of most- to ...

  18. Stability and Correlates of Student Evaluations of Teaching at a Chinese University

    ERIC Educational Resources Information Center

    Chen, Guo-Hai; Watkins, David

    2010-01-01

    This paper examines the stability and validity of a student evaluations of teaching (SET) instrument used by the administration at a university in the PR China. The SET scores for two semesters of courses taught by 435 teachers were collected. Total 388 teachers (170 males and 218 females) were also invited to fill out the 60-item NEO Five-Factor

  19. EVALUATION OF SOLIDIFICATION/STABILIZATION TREATMENT PROCESSES FOR MUNICIPAL WASTE COMBUSTION RESIDUES

    EPA Science Inventory

    Investigations were carried out to compare and evaluate solidification/stabilization (S/S) processes to treat residues from combustion (MWC). ull factorial experimental design was used to processes to treat bottom ash, air pollution control (APC) residue, The 5 S/S processes incl...

  20. A study on evaluation method of flotation frother`s froth stability

    SciTech Connect

    Xu Zhenhong; Zhu Jianhua; Zhang Rongzeng; Li Xi

    1998-12-31

    Frother plays an important role in the coal flotation. The frothability of common frothers for coal flotation was measured by using gas pulsation method in this paper. The relationship between froth height and half decay time was analyzed. In this article, several well-known frothability evaluation methods will have been analyzed and compared, and a new method of evaluating froth stability will be given.

  1. Evaluation of the voltage quantities measured with different noninvasive meters for quality control at a calibration laboratory.

    PubMed

    Vivolo, Vitor; Neves, Lucio P; Perini, Ana P; Silva, Jonas O; Lucena, Rodrigo F; da Penha A Potiens, Maria; Caldas, Linda V E

    2012-07-01

    In this work the peak kilovoltage (kVp), practical peak voltage (PPV) and air kerma rate were measured with the noninvasive meters Radcal Accu-kV® Diagnostic Sensor™ model 40×12-W, and PTW Diavolt. The results were compared in order to ensure the quality control, compare the meters and establish the new quantity PPV, at the Calibration Laboratory of IPEN. These tests were performed using the standard diagnostic radiology quality beam RQR5, and the results are in good agreement. PMID:22196679

  2. Evaluating stability and comparing output of feature selectors that optimize feature subset cardinality.

    PubMed

    Somol, Petr; Novovicov, Jana

    2010-11-01

    Stability (robustness) of feature selection methods is a topic of recent interest, yet often neglected importance, with direct impact on the reliability of machine learning systems. We investigate the problem of evaluating the stability of feature selection processes yielding subsets of varying size. We introduce several novel feature selection stability measures and adjust some existing measures in a unifying framework that offers broad insight into the stability problem. We study in detail the properties of considered measures and demonstrate on various examples what information about the feature selection process can be gained. We also introduce an alternative approach to feature selection evaluation in the form of measures that enable comparing the similarity of two feature selection processes. These measures enable comparing, e.g., the output of two feature selection methods or two runs of one method with different parameters. The information obtained using the considered stability and similarity measures is shown to be usable for assessing feature selection methods (or criteria) as such. PMID:20847385

  3. Evaluation of Laser Stabilization and Imaging Systems for LCLS-II - Final Paper

    SciTech Connect

    Barry, Matthew

    2015-08-20

    By combining the top performing commercial laser beam stabilization system with the most ideal optical imaging configuration, the beamline for the Linear Accelerator Coherent Light Source II (LCLS-II) will deliver the highest quality and most stable beam to the cathode. To determine the optimal combination, LCLS-II beamline conditions were replicated and the systems tested with a He-Ne laser. The Guidestar-II and MRC active laser beam stabilization systems were evaluated for their ideal positioning and stability. Both a two and four lens optical imaging configuration was then evaluated for beam imaging quality, magnification properties, and natural stability. In their best performances when tested over fifteen hours, Guidestar-II kept the beam stable over approximately 70-110um while the MRC system kept it stable over approximately 90-100um. During short periods of time, Guidestar-II kept the beam stable between 10-20um, but was more susceptible to drift over time, while the MRC system maintained the beam between 30-50um with less overall drift. The best optical imaging configuration proved to be a four lens system that images to the iris located in the cathode room and from there, imaged to the cathode. The magnification from the iris to the cathode was 2:1, within an acceptable tolerance to the expected 2.1:1 magnification. The two lens configuration was slightly more stable in small periods of time (less than 10 minutes) without the assistance of a stability system, approximately 55um compared to approximately 70um, but the four lens configurations beam image had a significantly flatter intensity distribution compared to the two lens configuration which had a Gaussian distribution. A final test still needs to be run with both stability systems running at the same time through the four lens system. With this data, the optimal laser beam stabilization system can be determined for the beamline of LCLS-II.

  4. Evaluation of Energy Characteristics of High Voltage Equipment for Electro-Blasting Destruction of Rocks and Concrete

    NASA Astrophysics Data System (ADS)

    Voitenko, N. V.; Yudin, A. S.; Kuznetsova, N. S.

    2015-11-01

    The splitting off concrete monolith via electro-blast technology is described. High- voltage investigations were performed using the electric-discharge blasting unit with charging voltage up to 15 kV and maximum energy of 126 kJ. Several series of experiments of multiborehole electro-blast with initiation of plasma channel by wire explosion have been carried out. The combined effect of pulse electric discharge and gas generating composition allows to increase the energy of electro-blasting. According to data obtained from experiments the average value of energy for concrete monolith splitting off of 1 m3 is about 1554 kJ. The energy of electrical discharge pulse is about 95 kJ and gas-generating composition has energy contribution of 3.8 kJ/g. For carrying out of one electric-discharge blasting experiment 6-8 minutes has been spent. Therefore, the efficiency of pulse power system is about (0.85-0.9) m3/h.

  5. Critical evaluation of the midgap-voltage-shift method for determining oxide trapped charge in irradiated MOS devices

    SciTech Connect

    Shanfield, Z.; Moriwaki, M.M.

    1987-12-01

    The validity of using midgap voltage shifts to determine radiation-induced oxide trapped charge is examined using thermally stimulated current (TSC), conductance, and C-V techniques. The assumption behind the midgap technique that all interface states are amphoteric P/sub b/ centers is shown to be not generally valid. Conductance measurements revealed a donor interface state in the upper half of the bandgap. Results obtained by combining data from TSC and high-frequency C-V measurements show the existence of three types of radiation-induced interface states: the P/sub b/ center, a donor state in the upper half of the bandgap, and an acceptor state in the lower half. No single surface potential exists that is the neutral point for N/sub it/ for all processes and radiation doses. Midgap voltage shifts do not generally correlate with oxide trapped charge determined from thermally stimulated current (TSC) measurements. The magnitude of the fractional deviation is typically less than a factor of unity but in some cases is as large as a factor of four. The significance of these errors needs to be determined for each application. Arguments and test supporting the validity of using TSC measurements for determining oxide trapped charge are presented.

  6. Evaluation of Stability Changes in Tapered and Parallel Wall Implants: A Human Clinical Trial

    PubMed Central

    Rokn, AR.; Ghahroudi, AAR. Rasouli; Mesgarzadeh, A.; Miremadi, AA.; Yaghoobi, S.

    2011-01-01

    Objective To determine the pattern of stability changes as a reflection of early healing around single-stage roughened-surface implants in humans utilizing resonance frequency analysis (RFA). Materials and Methods Hundred twenty-five patients who demanded dental implants were treated with two different implant (Nobel Biocare Replace and Strumman ITI) systems. Bone type was classified into four groups. RFA was used for direct measurement of implant stability on the day of implant placement and consecutively at 14, 30 and 60 days after placement. The data were analyzed with Student t test and regression analysis. Results Three-hundred four roughened surface implants placed in the maxilla and mandible were evaluated. In Replace implants the lowest mean stability measurement was at 30 days for all bone types and the stability did not change significantly in any of the bone types (p>0.05). ITI implants demonstrated the lowest stability at 60 days for type 1 and 30 days and baseline for type 2, 3 and 4 bones. In addition, there was significant differences in implant stability between bone types 1 and 4 (P<0.001), 2 and 3 (p<0.05), and bone types 3 and 4 (P=0.07) at all aforementioned times in ITI implants. In Replace implants, regarding the implant diameter, contrary to ITI implants, no significant stability changes were detected (p>0.05). No significant difference was observed regarding gender, age and lengths in both systems. Conclusion In comparison to ITI implants, Replace implants revealed no significant difference in the pattern of stability changes among different bone types. PMID:22509458

  7. Section IV.D.3 for DOE 2013 Annual Report: Novel Phosphazene-based Compounds to Enhance Safety and Stability of Cell Chemistries for High Voltage Applications (INL)

    SciTech Connect

    Kevin L. Gering; Mason K. Harrup; Eric J. Dufek; Sergiy V. Sazhin; Harry W. Rollins; David K. Jamison; Fred F. Stewart; John Burba

    2013-09-01

    Electrolytes play a central role in performance and aging in most electrochemical systems. As automotive and grid applications place a higher reliance on electrochemical stored energy, it becomes more urgent to have electrolyte components that enable optimal battery performance while promoting battery safety and longevity. Safety remains a foremost concern for widespread utilization of Li-ion technology in electric-drive vehicles, especially as the focus turns to higher voltage systems (5V). This work capitalizes on the long established INL expertise regarding phosphazene chemistry, aimed at battery-viable compounds for electrolytes and electrodes that are highly tolerant to abusive conditions. This report showcases our 2013 work for the DOE applied battery research (ABR) program, wherein testing results are summarized for INL electrolytes and alternative anode materials.

  8. Prospective clinical evaluation of mandibular implant overdentures: Part I--Retention, stability, and tissue response.

    PubMed

    Burns, D R; Unger, J W; Elswick, R K; Beck, D A

    1995-04-01

    Seventeen subjects with preexisting conventional complete dentures were evaluated in this prospective clinical study. Two implants were placed bilaterally in the anterior mandible. In a crossover experimental design, the conventional dentures were modified, and the retention, stability, and tissue response for conventional dentures were compared with implant overdentures that had O-ring and magnet overdenture attachments for all subjects. The study indicated statistical superiority of the implant overdenture to the conventional denture. The O-ring attachment proved significantly better than the magnet attachment for retention and stability. The soft tissue response showed a slight but significant improvement with implant overdenture therapy. PMID:7783014

  9. Stress wave communication in concrete: II. Evaluation of low voltage concrete stress wave communications utilizing spectrally efficient modulation schemes with PZT transducers

    NASA Astrophysics Data System (ADS)

    Siu, Sam; Qing, Ji; Wang, Kun; Song, Gangbing; Ding, Zhi

    2014-12-01

    Piezoelectric materials, traditionally used for structural health monitoring, have recently been used to implement stress wave communications. Within a protective encasing we fabricate a smart aggregate which enables transmission and reception of modulated stress waves for digital communication within concrete. Our research focuses on building a high efficiency stress wave communication system and comparing the performance of phase shift keying (PSK) with quadrature amplitude modulation (QAM). Our experiments evaluate the performance of QPSK and 16QAM implemented with our stress wave communication system at a transmit voltage ranging from 32 dBV to 37 dBV. We also demonstrate the increase in spectral efficiency of 16QAM compared to QPSK.

  10. Evaluation of Hose in Hose Transfer Line Service Life for Hanford's Interim Stabilization Program

    SciTech Connect

    TORRES, T.D.

    2000-08-24

    RPP-6153, Engineering Task Plan for Hose-in-Hose Transfer System for the Interim Stabilization Program, defines the programmatic goals, functional requirements, and technical criteria for the development and subsequent installation of transfer line equipment to support Hanford's Interim Stabilization Program. RPP-6028, Specification for Hose in Hose Transfer Lines for Hanford's Interim Stabilization Program, has been issued to define the specific requirements for the design, manufacture, and verification of transfer line assemblies for specific waste transfer applications. Included in RPP-6028 are tables defining the chemical constituents of concern to which transfer lines will be exposed. Current Interim Stabilization Program planning forecasts that the at-grade transfer lines will be required to convey pumpable waste for as much as three years after commissioning. Prudent engineering dictates that the equipment placed in service have a working life in excess of this forecasted time period, with some margin to allow for future adjustments to the planned schedule. This document evaluates the effective service life of the Hose-in-Hose Transfer Lines, based on information submitted by the manufacturer and published literature. The effective service life of transfer line assemblies is a function of several factors. Foremost among these are process fluid characteristics, ambient environmental conditions, and the manufacturer's stated shelf life. This evaluation examines the manufacturer's certification of shelf life, the manufacturer's certifications of chemical compatibility with waste, and published literature on the effects of exposure to ionizing radiation on the mechanical properties of elastomeric materials to evaluate transfer line service life.

  11. Intrinsic Surface Stability in LiMn2-xNix04-s (x = 0.45, 0.5) High Voltage Spinel Materials for Lithium Ion Batteries

    SciTech Connect

    Carroll, Kyler J; Yang, Ming-Che; Veith, Gabriel M; Dudney, Nancy J; Meng, Ying Shirley

    2012-01-01

    This work reports the surface stability of the high vollage Li ion cathode LiMn2_,Ni,Ooh\\ (x = 0.5, 0.45) by comparing thin fi lm and powder composite electrodes after cycling using X-ray photoelectron spectroscopy. The thin film electrodes offer the abili ty to probe the surface of the material without the need of a conductive agent and polymer binder typically used in composite electrodes. The resulls suggest that neither oxidation of PP6 to POF3 nor the decomposition of ethylene carbonate or dimethylene carbonate occurs on the surface of the spinel material. These resulls confirm the enhanced cycling stability and rate capability associated with the high vollage spinel material and suggests that the SE!IIayer fonns due to the reaction of electrochemically inactive components in composite electrodes with the electrolyte.

  12. Appearance of second plateau voltage

    NASA Technical Reports Server (NTRS)

    Halpert, G.

    1981-01-01

    Batteries used in TIROS N and NOAA A spacecraft were performance tested. Voltage levels are plotted in a series of graphs. Cell packs from four different manufacturers are evaluated for depth of charge.

  13. Social stability and HIV risk behavior: evaluating the role of accumulated vulnerability.

    PubMed

    German, Danielle; Latkin, Carl A

    2012-01-01

    This study evaluated a cumulative and syndromic relationship among commonly co-occurring vulnerabilites (homelessness, incarceration, low-income, residential transition) in association with HIV-related risk behaviors among 635 low-income women in Baltimore. Analysis included descriptive statistics, logistic regression, latent class analysis and latent class regression. Both methods of assessing multidimensional instability showed significant associations with risk indicators. Risk of multiple partners, sex exchange, and drug use decreased significantly with each additional domain. Higher stability class membership (77%) was associated with decreased likelihood of multiple partners, exchange partners, recent drug use, and recent STI. Multidimensional social vulnerabilities were cumulatively and synergistically linked to HIV risk behavior. Independent instability measures may miss important contextual determinants of risk. Social stability offers a useful framework to understand the synergy of social vulnerabilities that shape sexual risk behavior. Social policies and programs aiming to enhance housing and overall social stability are likely to be beneficial for HIV prevention. PMID:21259043

  14. Evaluation of iodine content and stability in recipes prepared with biofortified potatoes.

    PubMed

    Cerretani, Lorenzo; Comandini, Patrizia; Fumanelli, Davide; Scazzina, Francesca; Chiavaro, Emma

    2014-11-01

    Iodine is an essential micronutrient of the human diet. Deficiency of iodine is diffused in many areas of the world and mild deficiency is present also in developed countries around Europe. Biofortification of vegetables could represent a better strategy with respect to iodized salt in order to increase iodine intake. The aim of this study was evaluating the stability of iodine, derived from biofortified potatoes, in the preparation process of three Italian typical dishes: dumplings, vegetable pie, and focaccia bread. The obtained results showed a good stability of iodine in cooking processes, in particular, during baking of focaccia bread. Significant losses of iodine were detected during boiling of dumplings and baking of vegetable pie. Although the different stability during the cooking processes, the three dishes maintained a good final content of iodine, ranging from the 33.3% to 52.7% of daily recommended intake in adults for individual serving size. PMID:24828007

  15. Macrocyclic biphenyl tetraoxazoles: Synthesis, evaluation as G-quadruplex stabilizers and cytotoxic activity

    PubMed Central

    Blankson, Gifty A.; Pilch, Daniel S.; Liu, Angela A.; Liu, Leroy F.; Rice, Joseph E.; LaVoie, Edmond J.

    2014-01-01

    A series of macrocyclic biphenyl tetraoxazoles was synthesized. The latter stages of the synthetic approach allowed for the addition of varied N-protected ?-amino acids, which were subsequently deprotected and condensed to provide the desired macrocycles. Improved yields could be realized in the macrocyclization step of their synthesis relative to other macrocyclic G-quadruplex stabilizers. These 24-membered macrocycles were evaluated for their ability to stabilize G-quadruplex DNA and for their relative cytotoxicity against human tumor cells. These biphenyl tetraoxazoles were not strong ligands for G-quadruplex DNA relative to other macrocyclic polyoxazoles. This reduced stabilizing potential did correlate with their comparatively lower cytotoxic activity as observed in the human tumor cell lines, RPMI 8402 and KB3-1. These studies provide useful insights into the conformational requirements for the development of selective and more potent G-quadruplex ligands. PMID:23787291

  16. TECHNOLOGY EVALUATION REPORT: SILICATE TECHNOLOGY CORPORATION, SOLIDIFICATION/STABILIZATION OF PCP AND INORGANIC CONTAMINANTS IN SOILS SELMA, CA

    EPA Science Inventory

    A Superfund Innovative Technology Evaluation demonstration was conducted to evaluate the ability of the solidification/ stabilization treatment process developed by Silicate Technology Corporation (STC) to reduce the mobility and leaching potential of organic and inorganic contam...

  17. Evaluation of the impact of uncontrolled parametric perturbations on stability of automatic systems with logical control units

    NASA Astrophysics Data System (ADS)

    Moskvina, Svetlana M.; Yukhymchuk, Maria S.; Zhirnova, Oxana; Gromaszek, Konrad

    2015-12-01

    Paper presents a method that allows evaluating the impact of uncontrolled parametric perturbations on the stability of automatic systems with logical control units. The major difference of the proposed method is using analytical form for representing the stability of such systems which allows evaluating the parameters of self-excited oscillations.

  18. Methodologies for evaluating long-term stabilization designs of uranium mill tailings impoundments

    SciTech Connect

    Nelson, J.D.; Abt, S.R.; Volpe, R.L.; Van Zye, D.; Hinkle, N.E.; Staub, W.P.

    1986-06-01

    Uranium mill tailings impoundments require long-term (200 to 1000 years) stabilization. This report reviews currently available methodologies for evaluating factors that can have a significant influence on tailings stabilization and develops methodologies in technical areas where none presently exist. Mill operators can use these methodologies to assist with (1) the selection of sites for mill tailings impoundments, (2) the design of stable impoundments, and (3) the development of reclamation plans for existing impoundments. These methodologies would also be useful for regulatory agency evaluations of proposals in permit or license applications. Methodologies were reviewed or developed in the following technical areas: (1) prediction of the Probable Maximum Precipitation (PMP) and an accompanying Probable Maximum Flood (PMF); (2) prediction of the stability of local and regional fluvial systems; (3) design of impoundment surfaces resistant to gully erosion; (4) evaluation of the potential for surface sheet erosion; (5) design of riprap for protecting embankments from channel flood flow and overland flow; (6) selection of riprap with appropriate durability for its intended use; and (7) evaluation of oversizing required for marginal quality riprap.

  19. pH stability and comparative evaluation of ranaspumin-2 foam for application in biochemical reactors

    NASA Astrophysics Data System (ADS)

    Choi, Hyo-Jick; Ebersbacher, Charles F.; Quan, Fu-Shi; Montemagno, Carlo D.

    2013-02-01

    Aqueous channels of foam represent a simplified, natural bioreactor on the micro-/nano-scale. Previous studies have demonstrated the feasibility and potential application of foams in replicating cellular process in vitro, but no research has been performed to establish a basis for designing stable and biocompatible foam formulations. Our research has been directed specifically to the evaluation of ranaspumin-2 (RSN-2), a frog foam nest protein. The strong surfactant activity of RSN-2 enabled us to produce foams using low protein concentration (1 mg ml-1) over a wide pH range (pH ≥ 3). Importantly, the RSN-2 formulation exhibited the best foam stability at a near neutral pH condition, which shows a potential for application to various biosynthesis applications. Model cellular systems such as liposomes and inactivated A/PR/8/34 influenza virus maintained their physicochemical stability and full hemagglutination activity, indicating biocompatibility of RSN-2 with both cellular membranes and proteins both in bulk solution and in foam. Moreover, the addition of RSN-2 did not exert any deteriorative effects on bacterial cell growth kinetics. In contrast, Tween 20, Triton X-100, and BSA did not show satisfactory performance in terms of foamability, foam stability, physicochemcial stability, and biochemical stability. Although our study has been limited to representative formulations composed of only surfactant molecules, a number of unique advantages make RSN-2 a promising candidate for in vitro foam biosynthesis.

  20. Evaluation of the stability of concentrated emulsions for lemon beverages using sequential experimental designs.

    PubMed

    Almeida, Teresa Cristina Abreu; Larentis, Ariane Leites; Ferraz, Helen Conceição

    2015-01-01

    The study of the stability of concentrated oil-in-water emulsions is imperative to provide a scientific approach for an important problem in the beverage industry, contributing to abolish the empiricism still present nowadays. The use of these emulsions would directly imply a reduction of transportation costs between production and the sales points, where dilution takes place. The goal of this research was to evaluate the influence of the main components of a lemon emulsion on its stability, aiming to maximize the concentration of oil in the beverage and to correlate its physicochemical characteristics to product stability, allowing an increase of shelf life of the final product. For this purpose, analyses of surface and interface tension, electrokinetic potential, particle size and rheological properties of the emulsions were conducted. A 2(4-1) fractional factorial design was performed with the following variables: lemon oil/water ratio (30% to 50%), starch and Arabic gum concentrations (0% to 30%) and dioctyl sodium sulfosuccinate (0 mg/L to 100 mg/L), including an evaluation of the responses at the central conditions of each variable. Sequentially, a full design was prepared to evaluate the two most influential variables obtained in the first plan, in which concentration of starch and gum ranged from 0% to 20%, while concentration of lemon oil/water ratio was fixed at 50%, without dioctyl sodium sulfosuccinate. Concentrated emulsions with stability superior to 15 days were obtained with either starch or Arabic gum and 50% lemon oil. The most stable formulations presented viscosity over 100 cP and ratio between the surface tension of the emulsion and the mucilage of over 1. These two answers were selected, since they better represent the behavior of emulsions in terms of stability and could be used as tools for an initial selection of the most promising formulations. PMID:25793301

  1. Evaluation of the Stability of Concentrated Emulsions for Lemon Beverages Using Sequential Experimental Designs

    PubMed Central

    Almeida, Teresa Cristina Abreu; Larentis, Ariane Leites; Ferraz, Helen Conceição

    2015-01-01

    The study of the stability of concentrated oil-in-water emulsions is imperative to provide a scientific approach for an important problem in the beverage industry, contributing to abolish the empiricism still present nowadays. The use of these emulsions would directly imply a reduction of transportation costs between production and the sales points, where dilution takes place. The goal of this research was to evaluate the influence of the main components of a lemon emulsion on its stability, aiming to maximize the concentration of oil in the beverage and to correlate its physicochemical characteristics to product stability, allowing an increase of shelf life of the final product. For this purpose, analyses of surface and interface tension, electrokinetic potential, particle size and rheological properties of the emulsions were conducted. A 24-1 fractional factorial design was performed with the following variables: lemon oil/water ratio (30% to 50%), starch and Arabic gum concentrations (0% to 30%) and dioctyl sodium sulfosuccinate (0 mg/L to 100 mg/L), including an evaluation of the responses at the central conditions of each variable. Sequentially, a full design was prepared to evaluate the two most influential variables obtained in the first plan, in which concentration of starch and gum ranged from 0% to 20%, while concentration of lemon oil/water ratio was fixed at 50%, without dioctyl sodium sulfosuccinate. Concentrated emulsions with stability superior to 15 days were obtained with either starch or Arabic gum and 50% lemon oil. The most stable formulations presented viscosity over 100 cP and ratio between the surface tension of the emulsion and the mucilage of over 1. These two answers were selected, since they better represent the behavior of emulsions in terms of stability and could be used as tools for an initial selection of the most promising formulations. PMID:25793301

  2. ALD gate dielectrics for improved threshold voltage stability in AlGaN/GaN MOS-HFETs for power applications

    NASA Astrophysics Data System (ADS)

    Ramanan, Narayanan; Lee, Bongmook; Misra, Veena

    2015-12-01

    Dielectrics by atomic layer deposition (ALD) are sought after for fabricating AlGaN/GaN based metal oxide semiconductor heterojunction field effect transistors (MOS-HFETs) for power applications. The ideal gate dielectric is required to suppress gate leakage and minimize threshold voltage (V T) instability by hosting minimal interface traps. Additionally, with the need for an enhancement mode device, it is preferable if it minimizes V T shift in the negative direction. For the first time, we compare popular ALD dielectrics like SiO2, Al2O3, HfO2 and HfAlO with identical electrical thickness on AlGaN/GaN, thereby ensuring identical electrostatic conditions across different dielectrics. High-k ALD dielectrics (HfAlO, HfO2 and Al2O3) are found to suppress gate leakage but host a high density of interface traps with AlGaN, thereby resulting in significant V T instability. ALD SiO2 gate dielectric, annealed in N2 above 600 °C, is a promising gate dielectric candidate which provides the most stable and least negative shift in V T while also substantially suppressing gate leakage below that of an HFET.

  3. Evaluation of Available Transfer Capability Using Transient Stability Constrained Line Flows

    NASA Astrophysics Data System (ADS)

    Uzoechi, Lazarus Okechukwu; Mahajan, Satish M.

    2014-01-01

    This paper presents a methodology to evaluate transient stability constrained available transfer capability (ATC). A linear and fast line flow-based (LFB) method was adopted to optimize the ATC values. This enabled the direct determination of the system source-sink locations. This paper formulated different market transactions considering bilateral and multilateral impacts in the stability constrained ATC. The proposed method was demonstrated on the WECC 9-bus and IEEE 39-bus systems. The critical energy performance index (CEPI) enabled the direct identification of candidates for contingency screening based on ranking. This index helped to reduce the list of credible contingencies for ATC evaluation and, therefore, the computation time. The results of the proposed ATC method are consistent with the literature and can be deployed for fast assessment of the impact of transactions in an electric power system.

  4. Evaluation of the Magnesium Hydroxide Treatment Process for Stabilizing PFP Plutonium/Nitric Acid Solutions

    SciTech Connect

    Gerber, Mark A.; Schmidt, Andrew J.; Delegard, Calvin H.; Silvers, Kurt L.; Baker, Aaron B.; Gano, Susan R.; Thornton, Brenda M.

    2000-09-28

    This document summarizes an evaluation of the magnesium hydroxide [Mg(OH)2] process to be used at the Hanford Plutonium Finishing Plant (PFP) for stabilizing plutonium/nitric acid solutions to meet the goal of stabilizing the plutonium in an oxide form suitable for storage under DOE-STD-3013-99. During the treatment process, nitric acid solutions bearing plutonium nitrate are neutralized with Mg(OH)2 in an air sparge reactor. The resulting slurry, containing plutonium hydroxide, is filtered and calcined. The process evaluation included a literature review and extensive laboratory- and bench-scale testing. The testing was conducted using cerium as a surrogate for plutonium to identify and quantify the effects of key processing variables on processing time (primarily neutralization and filtration time) and calcined product properties.

  5. Evaluation of frac fluid stability using a heated, pressurized flow loop

    SciTech Connect

    Lescarboura, J.A.; Sifferman, T.R.; Wahl, H.A.

    1982-09-01

    A flow loop was used to evaluate the stability of frac fluids at high temperatures. The design provides enough pressure to prevent vaporization of water base systems up to 350/sup 0/F. The flow loop is a 25-gallon-capacity pipe viscosimeter with a 1-inch-diameter, 20-foot-long test section. Shear rates are variable, but most tests were run at values approximating the shear rates in a fracture. Shearing and heat exposure times of up to 6 hours were run. Cross-linked polymer systems from four service companies were prepared according to each supplier's recommendations and evaluated at 180/sup 0/ and 245/sup 0/F. The tests showed that cross-linked frac fluids degrade with temperature and shear, losing much of their viscosity and proppant-carrying capacity in a few hours. Thermal stability is a major factor in selecting gels for fracing deep, high-temperature reservoirs.

  6. Fabrication and evaluation of an OSO-1 type baseplate. [dimensional stability testing

    NASA Technical Reports Server (NTRS)

    Marschall, C. W.

    1975-01-01

    An OSO-1 type baseplate of a low thermal-expansion glass-ceramic material was evaluated for its dimensional stability after exposure to thermal cycling and mechanical vibration. The results indicate that baseplates of relatively simple design can be successfully cast and machined, although the demonstration article produced deviated somewhat from design specifications. It is likely that baseplates of more sophisticated designs and improved structural efficiency also can be prepared from low thermal expansion material.

  7. Evaluation of bias voltage modulation sequence for nonlinear contrast agent imaging using a capacitive micromachined ultrasonic transducer array.

    PubMed

    Novell, Anthony; Legros, Mathieu; Grgoire, Jean-Marc; Dayton, Paul A; Bouakaz, Ayache

    2014-09-01

    Many clinical diagnoses have now been improved thanks to the development of new techniques dedicated to contrast agent nonlinear imaging. Over the past few years, Capacitive Micromachined Ultrasonic Transducers (cMUTs) have emerged as a promising alternative to traditional piezoelectric transducers. One notable advantage of cMUTs is their wide frequency bandwidth. However, their use in nonlinear imaging approaches such as those used to detect contrast agents have been challenging due their intrinsic nonlinear character. We propose a new contrast imaging sequence, called bias voltage modulation (BVM), specifically developed for cMUTs to suppress their inherent nonlinear behavior. Theoretical and experimental results show that a complete cancellation of the nonlinear signal from the source can be reached when the BVM sequence is implemented. In-vitro validation of the sequence is performed using a cMUT probe connected to an open scanner and a flow phantom setup containing SonoVue microbubbles. Compared to the standard amplitude modulation imaging mode, a 6?dB increase of contrast-to-tissue ratio was achieved when the BVM sequence is applied. These results reveal that the problem of cMUT nonlinearity can be addressed, thus expanding the potential of this new transducer technology for nonlinear contrast agent detection and imaging. PMID:25098319

  8. Evaluation of bias voltage modulation sequence for nonlinear contrast agent imaging using a capacitive micromachined ultrasonic transducer array

    NASA Astrophysics Data System (ADS)

    Novell, Anthony; Legros, Mathieu; Grégoire, Jean-Marc; Dayton, Paul A.; Bouakaz, Ayache

    2014-09-01

    Many clinical diagnoses have now been improved thanks to the development of new techniques dedicated to contrast agent nonlinear imaging. Over the past few years, Capacitive Micromachined Ultrasonic Transducers (cMUTs) have emerged as a promising alternative to traditional piezoelectric transducers. One notable advantage of cMUTs is their wide frequency bandwidth. However, their use in nonlinear imaging approaches such as those used to detect contrast agents have been challenging due their intrinsic nonlinear character. We propose a new contrast imaging sequence, called bias voltage modulation (BVM), specifically developed for cMUTs to suppress their inherent nonlinear behavior. Theoretical and experimental results show that a complete cancellation of the nonlinear signal from the source can be reached when the BVM sequence is implemented. In-vitro validation of the sequence is performed using a cMUT probe connected to an open scanner and a flow phantom setup containing SonoVue microbubbles. Compared to the standard amplitude modulation imaging mode, a 6 dB increase of contrast-to-tissue ratio was achieved when the BVM sequence is applied. These results reveal that the problem of cMUT nonlinearity can be addressed, thus expanding the potential of this new transducer technology for nonlinear contrast agent detection and imaging.

  9. Field soil aggregate stability kit for soil quality and rangeland health evaluations

    USGS Publications Warehouse

    Herrick, J.E.; Whitford, W.G.; de Soyza, A. G.; Van Zee, J. W.; Havstad, K.M.; Seybold, C.A.; Walton, M.

    2001-01-01

    Soil aggregate stability is widely recognized as a key indicator of soil quality and rangeland health. However, few standard methods exist for quantifying soil stability in the field. A stability kit is described which can be inexpensively and easily assembled with minimal tools. It permits up to 18 samples to be evaluated in less than 10 min and eliminates the need for transportation, minimizing damage to soil structure. The kit consists of two 21??10.5??3.5 cm plastic boxes divided into eighteen 3.5??3.5 cm sections, eighteen 2.5-cm diameter sieves with 1.5-mm distance openings and a small spatula used for soil sampling. Soil samples are rated on a scale from one to six based on a combination of ocular observations of slaking during the first 5 min following immersion in distilled water, and the percent remaining on a 1.5-mm sieve after five dipping cycles at the end of the 5-min period. A laboratory comparison yielded a correlation between the stability class and percent aggregate stability based on oven dry weight remaining after treatment using a mechanical sieve. We have applied the method in a wide variety of agricultural and natural ecosystems throughout western North America, including northern Mexico, and have found that it is highly sensitive to differences in management and plant community composition. Although the field kit cannot replace the careful laboratory-based measurements of soil aggregate stability, it can clearly provide valuable information when these more intensive procedures are not possible.

  10. Partial discharge testing under direct voltage conditions

    NASA Technical Reports Server (NTRS)

    Bever, R. S.; Westrom, J. L.

    1982-01-01

    DC partial discharge (PD) (corona) testing is performed using a multichannel analyzer for pulse storing, and data is collected during increase of voltage and at quiescent voltage levels. Thus high voltage ceramic disk capacitors were evaluated by obtaining PD data interspersed during an accelerated life test. Increased PD activity was found early in samples that later failed catastrophically. By this technique, trends of insulation behavior are revealed sensitively and nondestructively in high voltage dc components.

  11. Biosynthesis of gold nanoparticles using catclaw buttercup (Radix Ranunculi Ternati) and evaluation of its colloidal stability.

    PubMed

    Ren, Fang; He, Xiaoxiao; Wang, Kemin; Yin, Jinjin

    2012-08-01

    The biosynthesis of gold nanoparticles using catclaw buttercup (Radix Ranunculi Ternati) and their stability have been reported in this paper. The aqueous catclaw buttercup was used as mild reducing agent for gold nanoparticles synthesis from HAuCl4 solutions. The influence of reaction time, temperature and mass ratio of HAuCl4/catclaw buttercup were evaluated to investigate their effects on gold nanoparticles synthesis. Under the optimized reaction parameters, the gold nanoparticles obtained are characterized by UV-vis spectrum, X-ray diffraction (XRD), EDAX technique (EDX), high resolution transmission electron microscopy (HRTEM), FTIR spectrum, anthrone-sulfuric colorimetric method, and plus Improved-Lowry Protein Assay Kit. The HRTEM images showed that the biosynthesized gold nanoparticles are mostly spherical with size range from 9-24 nm. Furthermore, it was found that the biosynthesized gold nanoparticles possessed outstanding colloid stability in aqueous solutions as a function of category and concentration of monovalent salt and pH value of the solution when compared with chemosynthetic ones with the similar size. Anthrone-sulfuric colorimetric method revealed that there is no sugar in the biosynthesized gold colloid. While Improved-Lowry tests results demonstrated that the existence of much protein in the biosynthesized gold colloid, which may played an important role in stabilization of it. Owing to their stability, biocompatibility, lower cost and so on, gold nanoparticles synthesized by this biosynthesis method show potential application prospect in optoelectronic and biomedicine. PMID:22852468

  12. Evaluation of the effectiveness of olive cake residue as an expansive soil stabilizer

    NASA Astrophysics Data System (ADS)

    Nalbantoglu, Zalihe; Tawfiq, Salma

    2006-08-01

    The quantity of the by-product olive cake residue generated in most parts of the Mediterranean countries continues to increase and expected to double in amount within 10 15 years. This increase intensifies the problems associated with the disposal of this by-product. Olive cake residue has a potential for use as a soil stabilizer and large volumes can be beneficially used. This study is directed toward determining if olive cake residue can be utilized to increase the strength and stability of expansive soils which constitute a costly natural hazard to lightweight structures on shallow foundations. A series of laboratory tests using engineering properties, such as Atterberg limits, moisture-density relationship (compaction), swell, unconfined compressive strength were undertaken to evaluate the effectiveness and performance of the olive cake residue as a soil stabilizer. Test results indicate that an addition of only 3% burned olive waste into the soil causes a reduction in plasticity, volume change and an increase in the unconfined compressive strength. However, it was observed that the presence of burned olive waste in the soil greater than 3% caused an increase in the compressibility and a decrease in the unconfined compressive strength. Test results indicate that the use of olive waste in soil stabilization gives greater benefits to the environment than simply disposing of the by-product, olive cake residue.

  13. Development and flight evaluation of an augmented stability active controls concept with a small horizontal tail

    NASA Technical Reports Server (NTRS)

    Rising, J. J.; Kairys, A. A.; Maass, C. A.; Siegart, C. D.; Rakness, W. L.; Mijares, R. D.; King, R. W.; Peterson, R. S.; Hurley, S. R.; Wickson, D.

    1982-01-01

    A limited authority pitch active control system (PACS) was developed for a wide body jet transport (L-1011) with a flying horizontal stabilizer. Two dual channel digital computers and the associated software provide command signals to a dual channel series servo which controls the stabilizer power actuators. Input sensor signals to the computer are pitch rate, column-trim position, and dynamic pressure. Control laws are given for the PACS and the system architecture is defined. The piloted flight simulation and vehicle system simulation tests performed to verify control laws and system operation prior to installation on the aircraft are discussed. Modifications to the basic aircraft are described. Flying qualities of the aircraft with the PACS on and off were evaluated. Handling qualities for cruise and high speed flight conditions with the c.g. at 39% mac ( + 1% stability margin) and PACS operating were judged to be as good as the handling qualities with the c.g. at 25% (+15% stability margin) and PACS off.

  14. Evaluation of degradation kinetics for abamectin in formulations using a stability indicating method.

    PubMed

    Awasthi, Atul; Razzak, Majid; Al-Kassas, Raida; Harvey, Joanne; Garg, Sanjay

    2013-03-01

    The aim of this study was to evaluate stability characteristics and kinetics behavior of abamectin (ABM) as a 1 % (m/V) topical veterinary solution. During the study, samples stressed at 55 and 70 C were regularly analyzed for several parameters over 8 weeks on a chromatographic (HPLC) system, using a Prodigy C18, 250 x 4.6 mm, 5-?m, column eluting with 15 : 34 : 51 (V/V/V) water/methanol/ acetonitrile as mobile phase. The HPLC method was validated for precision, accuracy, linearity and specificity, and was found to be stability indicating. The results showed that degradation of ABM followed first-order kinetics and data on loss in kobs (s-1) and half life (t1/2, days) demonstrated ABM showing the maximum stability in glycerol formal. The degradation behavior of ABM varies from solvent to solvent. The effect of added alkali on pH change and loss of ABM was studied and found to be unique for all solvents and very distinct from typical hydrolysis degradation. The present study may serve as a platform to design and develop topical non-aqueous solutions of ABM for veterinary use given no such comprehensive efforts have been published to date on the stability profile of ABM in non-aqueous solvents. PMID:23482313

  15. Evaluation of the Effects of Different Surface Configurations on Stability of Miniscrews

    PubMed Central

    Topcuoglu, Tolga; Bicakci, A. Altuğ; Avunduk, M. Cihat; Sahin Inan, Z. Deniz

    2013-01-01

    Introduction. The aim of this study was to analyze the effects of screw design and force application on the stability of miniscrews, using RTT, SEM, and histomorphometric analyses. Materials and Methods. Eighty cylindrical, self-drilling, and Ti6Al4V alloy miniscrews (1,6 × 6 mm) were used. Four mini-screws were inserted in fibulas of each rabbit, and 115 G of force was immediately applied. Four miniscrews were inserted in the other fibula, on which no force was applied. Eight weeks after insertion, osseointegration between miniscrew and the surrounding bone was evaluated by the histomorphometric analyses, SEM, and RTT. Kruskal-Wallis and the paired t-tests were used for statistical analysis. Results. Values obtained from Group I were significantly higher than those of the other loaded groups (P < .05). There were no differences in RTT scores among Groups II, III, and IV. Similar findings were also observed for unloaded mini-screws. There was no significant difference between Groups I and IC, while the differences between loaded and unloaded controls for each miniscrew were statistically significant. Conclusions. Immediate loading of miniscrews does not impair screw stability. Also, the diameter of miniscrew and more frequent thread pitches have a positive effect on stability; however, length of miniscrews does not have a significant effect on the stability. PMID:23935417

  16. Incorporating voltage security into the planning, operation and monitoring of restructured electric energy markets

    NASA Astrophysics Data System (ADS)

    Nair, Nirmal-Kumar

    As open access market principles are applied to power systems, significant changes are happening in their planning, operation and control. In the emerging marketplace, systems are operating under higher loading conditions as markets focus greater attention to operating costs than stability and security margins. Since operating stability is a basic requirement for any power system, there is need for newer tools to ensure stability and security margins being strictly enforced in the competitive marketplace. This dissertation investigates issues associated with incorporating voltage security into the unbundled operating environment of electricity markets. It includes addressing voltage security in the monitoring, operational and planning horizons of restructured power system. This dissertation presents a new decomposition procedure to estimate voltage security usage by transactions. The procedure follows physical law and uses an index that can be monitored knowing the state of the system. The expression derived is based on composite market coordination models that have both PoolCo and OpCo transactions, in a shared stressed transmission grid. Our procedure is able to equitably distinguish the impacts of individual transactions on voltage stability, at load buses, in a simple and fast manner. This dissertation formulates a new voltage stability constrained optimal power flow (VSCOPF) using a simple voltage security index. In modern planning, composite power system reliability analysis that encompasses both adequacy and security issues is being developed. We have illustrated the applicability of our VSCOPF into composite reliability analysis. This dissertation also delves into the various applications of voltage security index. Increasingly, FACT devices are being used in restructured markets to mitigate a variety of operational problems. Their control effects on voltage security would be demonstrated using our VSCOPF procedure. Further, this dissertation investigates the application of steady state voltage stability index to detect potential dynamic voltage collapse. Finally, this dissertation examines developments in representation, standardization, communication and exchange of power system data. Power system data is the key input to all analytical engines for system operation, monitoring and control. Data exchange and dissemination could impact voltage security evaluation and therefore needs to be critically examined.

  17. New Method of Evaluating Relative Thermal Stabilities of Proteins Based on Their Amino Acid Sequences:. Targetstar

    NASA Astrophysics Data System (ADS)

    Kim, Haejin; Moon, Eun-Joung; Moon, Sungchul; Jung, Ho-Jin; Yang, Young-Lyeol; Park, Young-Hoon; Heo, Muyoung; Cheon, Mookyung; Chang, Iksoo; Han, Dong-Soo

    Several computational methods have been developed to solve the problem of protein thermostabilization. One common drawback of them is that they must have the information of a backbone structure of a protein for the generation of a proper amino acid sequence. In this paper, we propose a new method called TargetStar by incorporating computational biology and statistical physics, in which an approximate partition function and a specific heat are used to calculate the folding transition temperature of a protein and then to predict the relative thermal stabilities for given proteins based only on their amino acid sequences. To evaluate the prediction accuracy of TargetStar, we calculated folding transition temperatures of 289 orthologous protein pairs using the proposed method, where each protein pair contains one hyperthermophilic protein and one mesophilic protein. According to our evaluation, hyperthermophilic and mesophilic proteins are distinguished from each other in terms of relative thermal stabilities with 77% prediction accuracy. Thus, TargetStar may serve as an efficient method to design an amino acid sequence of a target protein with the desired thermal stability prior to the expensive and time-consuming mutagenesis experiment.

  18. Stability evaluation of thermosensitive drug carrier systems based on Pluronic F-127 polymer.

    PubMed

    Grela, Kamil P; Marciniak, Dominik M; Pluta, Janusz

    2014-01-01

    The aim of this study was to evaluate the stability of thermosensitive systems based on Pluronic F-127 polymer, in aspects of their possible application in novel drug technology. A formulation was prepared without any active ingredient, consisting of 16% (w/w) of polymer dissolved in aqueous medium. Such preparation was autoclaved and then subjected to 3-month conditioning at elevated (40 degrees) and reduced (5 degrees C) temperature. Rheological parameters: viscosity, consistency and sol-gel transition characteristics were studied in 1-month interval. The significance of measured changes was evaluated by proper statistical analyses. Significant changes exceeding the established criteria (+/- 10% of every initial value) were observed during the study. Furthermore, total involution of sol-gel transition phenomenon was observed in samples stored at 40 degrees C. Results indicate the lack of stability in tested formulation at both of storage conditions. However, some regularity indicates that the stability at reduced temperature could be confirmed, if only the concentration of polymer and the measurements schedule were slightly modified. PMID:24779205

  19. Evaluation of an Intramedullary Bone Stabilization System Using a Light-Curable Monomer in Sheep

    PubMed Central

    Zani, Brett G.; Baird, Rose; Stanley, James R.L.; Markham, Peter M.; Wilke, Markus; Zeiter, Stephan; Beck, Aswin; Nehrbass, Dirk; Kopia, Gregory A.; Edelman, Elazer R.; Rabiner, Robert

    2015-01-01

    Percutaneous intramedullary fixation may provide an ideal method for stabilization of bone fractures, while avoiding the need for large tissue dissections. Tibiae in 18 sheep were treated with an intramedullary photodynamic bone stabilization system (PBSS) comprised of a polyethylene terephthalate (Dacron) balloon filled with a monomer and cured with visible light in situ then harvested at 30, 90 or 180 days. In an additional 40 sheep, a mid-shaft tibial osteotomy was performed and stabilized with external fixators or external fixators combined with the PBSS and evaluated at 8, 12 and 26 weeks. Healing and biocompatibility were evaluated by radiographic analysis, microCT and/or histopathology. In non-fractured sheep tibiae, PBSS implants conformably filled the medullary canal, while active cortical bone remodeling and apposition of new periosteal and/or endosteal bone was observed with no significant macroscopic or microscopic observations. Fractured sheep tibiae exhibited increased bone formation inside the osteotomy gap with no significant difference when fixation was augmented by PBSS implants. Periosteal callus size gradually decreased over time and was similar in both treatment groups. No inhibition of endosteal bone remodeling or vascularization was observed with PBSS implants. Intramedullary application of a light curable PBSS is a biocompatible, feasible method for fracture fixation. PMID:25772144

  20. The idea of PGA stream computations for soil slope stability evaluation

    NASA Astrophysics Data System (ADS)

    Tran, Chi; Srokosz, Piotr

    2010-09-01

    Designing and constructing of road embankments, deep excavations, landslide and snow avalanche predictions or profiling construction sites in slanting terrain need slope stability evaluations. Determination of a safety factor and the position of a potentially critical slip surface is one of the essential issues in classical and modern soil mechanics, which still remains a very important problem in engineering practice. Most of the stability evaluation methods, i.e. based on limit equilibrium assumptions, need optimization, which can be successfully realized with the assistance of a genetic algorithm. The authors propose a variational approach with a four-step technique to determination of the critical height of a slope, which can be treated as an alternative and variant method to the generally applied limit equilibrium and/or finite element methods. Some common obstacles encountered while adapting classical optimization procedures have been solved by application of a parallel genetic algorithm. Substantial acceleration of computations has been achieved by introducing SIMD stream technology, which generally relies on modern graphics processing units. Examples of the results of a slope stability analysis performed using the fast parallel computation technique are also presented.

  1. Evaluation of an intramedullary bone stabilization system using a light-curable monomer in sheep.

    PubMed

    Zani, Brett G; Baird, Rose; Stanley, James R L; Markham, Peter M; Wilke, Markus; Zeiter, Stephan; Beck, Aswin; Nehrbass, Dirk; Kopia, Gregory A; Edelman, Elazer R; Rabiner, Robert

    2016-02-01

    Percutaneous intramedullary fixation may provide an ideal method for stabilization of bone fractures, while avoiding the need for large tissue dissections. Tibiae in 18 sheep were treated with an intramedullary photodynamic bone stabilization system (PBSS) that comprised a polyethylene terephthalate (Dacron) balloon filled with a monomer, cured with visible light in situ, and then harvested at 30, 90, or 180 days. In additional 40 sheep, a midshaft tibial osteotomy was performed and stabilized with external fixators or external fixators combined with the PBSS and evaluated at 8, 12, and 26 weeks. Healing and biocompatibility were evaluated by radiographic analysis, micro-computed tomography, and histopathology. In nonfractured sheep tibiae, PBSS implants conformably filled the medullary canal, while active cortical bone remodeling and apposition of new periosteal and/or endosteal bone was observed with no significant macroscopic or microscopic observations. Fractured sheep tibiae exhibited increased bone formation inside the osteotomy gap, with no significant difference when fixation was augmented by PBSS implants. Periosteal callus size gradually decreased over time and was similar in both treatment groups. No inhibition of endosteal bone remodeling or vascularization was observed with PBSS implants. Intramedullary application of a light-curable PBSS is a biocompatible, feasible method for fracture fixation. 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 291-299, 2016. PMID:25772144

  2. Evaluation of the geological relationships to gas hydrate formation and stability

    SciTech Connect

    Not Available

    1986-01-01

    Although there are many publications pertaining to gas hydrates, their formation and stability in various geological conditions are poorly known. Therefore, for the same reasons and because of the very broad scope of our research, limited amount and extremely dispersed information, the study regions are very large. Moreover, almost without exception the geological environments controlling gas hydrates formation and stability of the studied regions are very complex. The regions studied (completed and partially completed - total 17 locations) during the reporting period, particularly the Gulf of Mexico and the Middle America Trench, are the most important in this entire research project. In the past, both of these regions have been extensively studied, the presence of gas hydrates confirmed and samples recovered. In our investigation it was necessary not only to review all previous data and interpretations, but to do a thorough analysis of the basins, and a critical evaluation of an previously reported and publicly available but not published information.

  3. Initial Flight Evaluation of the Army/NASA RASCAL Variable Stability Helicopter

    NASA Technical Reports Server (NTRS)

    Moralez, Ernesto, III; Hindson, William S.; Arterburn, David R.

    2000-01-01

    NASA Ames Research Center and the U.S. Army Aeroflightdynamics Directorate (AFDD) [will] have performed initial flight evaluations of the Research Flight Control System (RFCS) that has been integrated into the Army/NASA Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) variable stability helicopter. The RASCAL, a highly modified JUH-60A Black Hawk helicopter, is a variable-stability, in-flight simulator that is designed to support flight research programs that leverage on the flight control and handling qualities design tools developed by the Army and NASA. These tools are used in the flight control design life cycle from initial concept definition, through simulation, and ultimately into flight on-board the RASCAL helicopter. The RASCAL will be used to validate methodologies for reducing design cycle costs for new or modified aircraft, and it will serve as a base for the investigation of new rotorcraft technology.

  4. Implant stability evaluation by resonance frequency analysis in the fit lock technique. A clinical study

    PubMed Central

    Falisi, Giovanni; Galli, Massimo; Velasquez, Pedro Vittorini; Rivera, Juan Carlos Gallegos; Di Paolo, Carlo

    2013-01-01

    Summary Surgical procedures for the application of implants in the lateral-superior sectors are affected by the availability of the residual bone. When this condition is lower than 5 mm it is recommended that techniques involving two therapeutic phases, a reconstructive and an applicative one, as reported in the international literature, are adopted. The authors propose here a new method with the potential to apply implants simultaneously with the reconstructive phase. The aim of this longitudinal retrospective study was to evaluate the stability of implants applied with the fit lock technique in the upper maxillarys in us with bone availability lower than 4 mm by measuring resonance frequency at different follow-up periods The seme as urements, carried out on 30 implants, were analysed with specific statistical procedures. The results indicate that the stability of the implants inserted with the fit lock method increases progressively over time in a statistically significant manner. The stability recorded after one year from the insertion (ISQ T2) is significantly higher than that recorded after six months (ISQ T1), and this is significantly higher than that recorded at the time of implant placement (ISQ T0). The implants inserted in the maxillary zones with scarce bone availability and applied with this technique showed a similar stability as reported with other techniques. In light of the results, the authors confirm that the primary stability represents the basic requirement to guarantee a correct healing of the implant and demonstrate that the fit lock technique also all ows reaching this condition when bone availability is minimal. PMID:23991271

  5. Effects of sample storage on biosolids compost stability and maturity evaluation.

    PubMed

    Wu, L; Ma, L Q

    2001-01-01

    Compost stability and maturity are important parameters of compost quality. To date, nearly all compost characterization has been performed using samples freshly collected because sample storage can affect compost stability and maturity evaluation. However, sample preservation is sometimes necessary, especially for scientific research purposes. There is little information available on the effects of sample storage on compost stability and maturity. Samples of biosolids compost with different levels of stability and maturity were collected from four compost facilities in Florida (referred to as Register, Winslow, Sunset, and Meadow). Comparisons of CO2 evolution, seed germination rate, and water-soluble organic carbon (WSOC) were made between fresh samples with short storage at 4 degrees C for less than 1 wk and air-dried or frozen compost samples stored for 1 yr. The effects of storage (air-dry or frozen) on the measured parameters depended on compost stability and maturity and on the compost material source. Frozen storage reduced the peak CO2 evolution of Register samples by 12 to 29%, while accumulated CO2 evolution was reduced by 43 to 64% and 110 to 277% with air-dry and frozen storage, respectively. The storage effect on CO2 evolution with more stable compost was inconsistent. Storage did not affect compost phytotoxicity, except for samples from the Sunset facility. Air-drying reduced the WSOC by up to 35%, and freezing increased it by up to 34%, while both storage methods had no significant effect on samples of low WSOC. Despite all these variations, WSOC had a significant and consistent relation to CO2 evolution and seed germination rates with R2 of 0.78 and 0.57, respectively, regardless of storage methods. PMID:11215657

  6. International Comparative Evaluation of Fixed-Bearing Non-Posterior-Stabilized and Posterior-Stabilized Total Knee Replacements

    PubMed Central

    Comfort, Thomas; Baste, Valborg; Froufe, Miquel Angel; Namba, Robert; Bordini, Barbara; Robertsson, Otto; Cafri, Guy; Paxton, Elizabeth; Sedrakyan, Art; Graves, Stephen

    2014-01-01

    Background: Differences in survivorship of non-posterior-stabilized compared with posterior-stabilized knee designs carry substantial economic consequences, especially with limited health-care resources. However, these comparisons have often been made between relatively small groups of patients, often with short-term follow-up, with only small differences demonstrated between the groups. The goal of this study is to compare the outcomes of non-posterior-stabilized and posterior-stabilized total knee arthroplasties with use of a unique collaboration of multiple established knee arthroplasty registries. Methods: A distributed health data network was developed by the International Consortium of Orthopaedic Registries and was used in this study to reduce barriers to participation (such as security, propriety, legal, and privacy issues) compared with a centralized data warehouse approach. The study included only replacements in osteoarthritis patients who underwent total knee procedures involving fixed-bearing devices from 2001 to 2010. The outcome of interest was time to first revision. Results: On average, not resurfacing showed a more harmful effect than resurfacing did when posterior-stabilized and non-posterior-stabilized knee replacements were compared, while the risk of revision for posterior-stabilized compared with non-posterior-stabilized knees was highest in year zero to one, followed by year one to two, years eight through ten, and years two through eight. Posterior-stabilized knees did significantly worse than non-posterior-stabilized knees did when the patella was not resurfaced. This difference was most pronounced in the first two years (year zero to one: hazard ratio [HR] = 2.15, 95% confidence interval [CI] = 1.56 to 2.95, p < 0.001; year one to two: HR = 1.61, 95% CI = 1.48 to 1.75, p < 0.001). When the patella was resurfaced, posterior-stabilized knees did significantly worse than non-posterior-stabilized knees did. This was again most pronounced in the first two years (year zero to one: HR = 1.75, 95% CI = 1.27 to 2.42, p = 0.001; year one to two: HR = 1.31, 95% CI = 1.19 to 1.45, p < 0.001). There was a reduced risk of revision with a patient age of more than sixty-five years (HR = 0.57, 95% CI = 0.55 to 0.60, p < 0.001). Conclusions: We found that fixed non-posterior-stabilized total knee arthroplasty performed better with or without patellar resurfacing than did fixed posterior-stabilized total knee arthroplasty. This effect was most pronounced in the first two years. The risk of revision for posterior-stabilized total knee arthroplasties was reduced with patellar resurfacing. Also, a patient age of more than sixty-five years and female gender reduced the risk of revision. PMID:25520421

  7. Synthesis and evaluation of a 125I-labeled iminodihydroquinoline-derived tracer for imaging of voltage-gated sodium channels?

    PubMed Central

    Prez-Medina, Carlos; Patel, Niral; Robson, Mathew; Lythgoe, Mark F.; rstad, Erik

    2013-01-01

    In vivo imaging of voltage-gated sodium channels (VGSCs) can potentially provide insights into the activation of neuronal pathways and aid the diagnosis of a number of neurological diseases. The iminodihydroquinoline WIN17317-3 is one of the most potent sodium channel blockers reported to date and binds with high affinity to VGSCs throughout the rat brain. We have synthesized a 125I-labeled analogue of WIN17317-3 and evaluated the potential of the tracer for imaging of VGSCs with SPECT. Automated patch clamp studies with CHO cells expressing the Nav1.2 isoform and displacement studies with [3H]BTX yielded comparable results for the non-radioactive iodinated iminodihydroquinoline and WIN17317-3. However, the 125I-labeled tracer was rapidly metabolized in vivo, and suffered from low brain uptake and high accumulation of radioactivity in the intestines. The results suggest that iminodihydroquinolines are poorly suited for tracer development. PMID:23910595

  8. Performance Evaluation and Slip Regulation Control of an Asymmetrical Parameter Type Two-Phase Induction Motor Drive Using a Three-Leg Voltage Source Inverter

    NASA Astrophysics Data System (ADS)

    Piyarat, Wekin; Kinnares, Vijit

    This paper presents a performance evaluation and a simple speed control method of an asymmetrical parameter type two-phase induction motor drive using a three-leg VSI (Voltage Source Inverter). The two-phase induction motor is adapted from an existing single-phase induction motor resulting in impedance unbalance between main and auxiliary windings. The unbalanced two-phase inverter outputs with orthogonal displacement based on a SPWM (Sinusoidal Pulse Width Modulation) method are controlled with appropriate amplitudes for improving the motor performance. Dynamic simulation of the proposed drive system is given. A simple speed controller based on a slip regulation method is designed. The overall system is implemented on a DSP (Digital Signal Processor) board. The validity of the proposed system is verified by simulation and experimental results.

  9. Evaluating the Performance of a Battery Using Temperature and Voltage Profiles and a Battery-Resistor Circuit Module

    ERIC Educational Resources Information Center

    Sawyer, Bryan; Ji, Michelle; Gordon, Michael J.; Suppes, Galen J.

    2010-01-01

    An experimental learning module has been developed to study the mass and energy balance involved with operation of an AA Alkaline battery under a load current. An extension of the module allows evaluation of laboratory-assembled batteries using granular anodic/cathodic materials. The system allows load resistance to be varied and measures voltage…

  10. The Dynamic Evaluation of Rock Slope Stability Considering the Effects of Microseismic Damage

    NASA Astrophysics Data System (ADS)

    Xu, N. W.; Dai, F.; Liang, Z. Z.; Zhou, Z.; Sha, C.; Tang, C. A.

    2014-03-01

    A state-of-the-art microseismic monitoring system has been implemented at the left bank slope of the Jinping first stage hydropower station since June 2009. The main objectives are to ensure slope safety under continuous excavation at the left slope, and, very recently, the safety of the concrete arch dam. The safety of the excavated slope is investigated through the development of fast and accurate real-time event location techniques aimed at assessing the evolution and migration of the seismic activity, as well as through the development of prediction capabilities for rock slope instability. Myriads of seismic events at the slope have been recorded by the microseismic monitoring system. Regions of damaged rock mass have been identified and delineated on the basis of the tempo-spatial distribution analysis of microseismic activity during the periods of excavation and consolidation grouting. However, how to effectively utilize the abundant microseismic data in order to quantify the stability of the slope remains a challenge. In this paper, a rock mass damage evolutional model based on microseismic data is proposed, combined with a 3D finite element method (FEM) model for feedback analysis of the left bank slope stability. The model elements with microseismic damage are interrogated and the deteriorated mechanical parameters determined accordingly. The relationship between microseismic activities induced by rock mass damage during slope instability, strength degradation, and dynamic instability of the slope are explored, and the slope stability is quantitatively evaluated. The results indicate that a constitutive relation considering microseismic damage is concordant with the simulation results and the influence of rock mass damage can be allowed for its feedback analysis of 3D slope stability. In addition, the safety coefficient of the rock slope considering microseismic damage is reduced by a value of 0.11, in comparison to the virgin rock slope model. Our results demonstrate that microseismic activity induced by construction disturbance only slightly affects the stability of the slope. The proposed feedback analysis technique provides a novel method for dynamically assessing rock slope stability and can be used to assess the slope stability of other similar rock slopes.

  11. Combined Use of Automatic Tube Voltage Selection and Current Modulation with Iterative Reconstruction for CT Evaluation of Small Hypervascular Hepatocellular Carcinomas: Effect on Lesion Conspicuity and Image Quality

    PubMed Central

    Lv, Peijie; Liu, Jie; Zhang, Rui; Jia, Yan

    2015-01-01

    Objective To assess the lesion conspicuity and image quality in CT evaluation of small (? 3 cm) hepatocellular carcinomas (HCCs) using automatic tube voltage selection (ATVS) and automatic tube current modulation (ATCM) with or without iterative reconstruction. Materials and Methods One hundred and five patients with 123 HCC lesions were included. Fifty-seven patients were scanned using both ATVS and ATCM and images were reconstructed using either filtered back-projection (FBP) (group A1) or sinogram-affirmed iterative reconstruction (SAFIRE) (group A2). Forty-eight patients were imaged using only ATCM, with a fixed tube potential of 120 kVp and FBP reconstruction (group B). Quantitative parameters (image noise in Hounsfield unit and contrast-to-noise ratio of the aorta, the liver, and the hepatic tumors) and qualitative visual parameters (image noise, overall image quality, and lesion conspicuity as graded on a 5-point scale) were compared among the groups. Results Group A2 scanned with the automatically chosen 80 kVp and 100 kVp tube voltages ranked the best in lesion conspicuity and subjective and objective image quality (p values ranging from < 0.001 to 0.004) among the three groups, except for overall image quality between group A2 and group B (p = 0.022). Group A1 showed higher image noise (p = 0.005) but similar lesion conspicuity and overall image quality as compared with group B. The radiation dose in group A was 19% lower than that in group B (p = 0.022). Conclusion CT scanning with combined use of ATVS and ATCM and image reconstruction with SAFIRE algorithm provides higher lesion conspicuity and better image quality for evaluating small hepatic HCCs with radiation dose reduction. PMID:25995682

  12. A battery-based, low-noise voltage source.

    PubMed

    Wagner, Anke; Sturm, Sven; Schabinger, Birgit; Blaum, Klaus; Quint, Wolfgang

    2010-06-01

    A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of +/-15 and +/-5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7 x 10(-7) over 6.5 h and a noise level equal or smaller than 30 nV/square root(Hz) is achieved. PMID:20590260

  13. A battery-based, low-noise voltage source

    NASA Astrophysics Data System (ADS)

    Wagner, Anke; Sturm, Sven; Schabinger, Birgit; Blaum, Klaus; Quint, Wolfgang

    2010-06-01

    A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of ±15 and ±5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7×10-7 over 6.5 h and a noise level equal or smaller than 30 nV/√Hz is achieved.

  14. EVALUATION OF TWO LEAD-BASED PAINT REMOVAL AND WASTE STABILIZATION TECHNOLOGY COMBINATIONS ON TYPICAL EXTERIOR SURFACES

    EPA Science Inventory

    A study was conducted to demonstrate the effectiveness of a wet abrasive blasting technology to remove lead-based paint from exterior wood siding and brick substrates as well as to evaluate the effectiveness of two waste stabilization technologies to stabilize the resulting blast...

  15. Voltage collapse in complex power grids

    PubMed Central

    Simpson-Porco, John W.; Dörfler, Florian; Bullo, Francesco

    2016-01-01

    A large-scale power grid's ability to transfer energy from producers to consumers is constrained by both the network structure and the nonlinear physics of power flow. Violations of these constraints have been observed to result in voltage collapse blackouts, where nodal voltages slowly decline before precipitously falling. However, methods to test for voltage collapse are dominantly simulation-based, offering little theoretical insight into how grid structure influences stability margins. For a simplified power flow model, here we derive a closed-form condition under which a power network is safe from voltage collapse. The condition combines the complex structure of the network with the reactive power demands of loads to produce a node-by-node measure of grid stress, a prediction of the largest nodal voltage deviation, and an estimate of the distance to collapse. We extensively test our predictions on large-scale systems, highlighting how our condition can be leveraged to increase grid stability margins. PMID:26887284

  16. Voltage collapse in complex power grids

    NASA Astrophysics Data System (ADS)

    Simpson-Porco, John W.; Dörfler, Florian; Bullo, Francesco

    2016-02-01

    A large-scale power grid's ability to transfer energy from producers to consumers is constrained by both the network structure and the nonlinear physics of power flow. Violations of these constraints have been observed to result in voltage collapse blackouts, where nodal voltages slowly decline before precipitously falling. However, methods to test for voltage collapse are dominantly simulation-based, offering little theoretical insight into how grid structure influences stability margins. For a simplified power flow model, here we derive a closed-form condition under which a power network is safe from voltage collapse. The condition combines the complex structure of the network with the reactive power demands of loads to produce a node-by-node measure of grid stress, a prediction of the largest nodal voltage deviation, and an estimate of the distance to collapse. We extensively test our predictions on large-scale systems, highlighting how our condition can be leveraged to increase grid stability margins.

  17. Voltage collapse in complex power grids.

    PubMed

    Simpson-Porco, John W; Dörfler, Florian; Bullo, Francesco

    2016-01-01

    A large-scale power grid's ability to transfer energy from producers to consumers is constrained by both the network structure and the nonlinear physics of power flow. Violations of these constraints have been observed to result in voltage collapse blackouts, where nodal voltages slowly decline before precipitously falling. However, methods to test for voltage collapse are dominantly simulation-based, offering little theoretical insight into how grid structure influences stability margins. For a simplified power flow model, here we derive a closed-form condition under which a power network is safe from voltage collapse. The condition combines the complex structure of the network with the reactive power demands of loads to produce a node-by-node measure of grid stress, a prediction of the largest nodal voltage deviation, and an estimate of the distance to collapse. We extensively test our predictions on large-scale systems, highlighting how our condition can be leveraged to increase grid stability margins. PMID:26887284

  18. SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS

    SciTech Connect

    MCSHANE DS

    2010-03-25

    After 1970 Transuranic (TRU) and suspect TRU waste was buried in the ground with the intention that at some later date the waste would be retrieved and processed into a configuration for long term storage. To retrieve this waste the soil must be removed (excavated). Sloping the bank of the excavation is the method used to keep the excavation from collapsing and to provide protection for workers retrieving the waste. The purpose of this paper is to document the minimum distance (setback) that equipment must stay from the edge of the excavation to maintain a stable slope. This evaluation examines the equipment setback distance by dividing the equipment into two categories, (1) equipment used for excavation and (2) equipment used for retrieval. The section on excavation equipment will also discuss techniques used for excavation including the process of benching. Calculations 122633-C-004, 'Slope Stability Analysis' (Attachment A), and 300013-C-001, 'Crane Stability Analysis' (Attachment B), have been prepared to support this evaluation. As shown in the calculations the soil has the following properties: Unit weight 110 pounds per cubic foot; and Friction Angle (natural angle of repose) 38{sup o} or 1.28 horizontal to 1 vertical. Setback distances are measured from the top edge of the slope to the wheels/tracks of the vehicles and heavy equipment being utilized. The computer program utilized in the calculation uses the center of the wheel or track load for the analysis and this difference is accounted for in this evaluation.

  19. Converter Circuit Voltage-Voltage Investigation for Power Calibrator

    NASA Astrophysics Data System (ADS)

    Fomichev, Yu M.; Silushkin, S. V.; Mylnikova, T. S.

    2016-01-01

    The paper presents possible circuits to construct a voltage-voltage converter for the calibrator of fictitious power. The problems of circuit solutions were experimentally identified, and the ways of their elimination were found. One of the main problems of convectors is to provide small harmonic distortions and additional phase shift. The use of deep negative instantaneous value feedback helps to provide the desired level of nonlinear distortions and to reduce the phase shift. Corrective circuits are used to ensure the stability of the transducer at greater depths of the feedback; the half-period average value or rms value feedback is used to ensure the stability and accuracy of conversion. However, the accuracy of the power calibrator can be upgraded and its work for various types of loads can be ensured by means of application follower circuit with modern electronic components which are also discussed in the paper.

  20. Analysis of static noise margin improvement for low voltage SRAM composed of nano-scale MOSFETs with ideal subthreshold factor and small variability

    NASA Astrophysics Data System (ADS)

    Tanaka, Chika; Saitoh, Masumi; Ota, Kensuke; Numata, Toshinori

    2015-07-01

    An ultra-low voltage performance of nanowire-transistors-based SRAM cell is investigated using the SPICE model parameters extracted from measurement data. The impact of S-factor and threshold voltage variations on the static noise margin and the minimum operating voltage is evaluated in nanowire transistor as well as in planar bulk transistor and quasi-planar bulk transistor. The performance benefits of undoped nanowire-transistor-based SRAM are measured in terms of the read stability for low voltage and low off leakage current operation.

  1. Evaluation of Thermal Stability of Nomex Brand Paper in Main Transformer of Shinkansen Train Series 100

    NASA Astrophysics Data System (ADS)

    Tanaka, Hirokazu; Kondo, Chihiro; Naruse, Shinji; Ishii, Yoshitada

    Nomex brand paper has been used as wire wrapping insulation material of main transformers of Shinkansen Train Series 100 with silicone oil. After approximately 12-13 years service, 8 transformers of Series 100 were sampled to evaluate degradation of Nomex brand paper in terms of tensile strength and intrinsic viscosity. All data were compared with initial data. The result of less degradation shows Nomex has good thermal stability in silicone oil in the main transformer of Shinkansen Train which were used in very severe condition.

  2. Reliability of a New Stabilized Dynamometer System for the Evaluation of Hip Strength

    PubMed Central

    Tourville, Timothy W.; Smith, Helen C.; Shultz, Sandra J.; Vacek, Pamela M.; Slauterbeck, James R.; Johnson, Robert J.; Beynnon, Bruce D.

    2013-01-01

    Background: Hip strength is associated with numerous orthopaedic and neuromuscular injuries and/or pathologies and may be assessed with a variety of anatomic testing positions and techniques. Isokinetic dynamometers are generally too cumbersome and intricate for efficient use in mass screenings (for prognostic studies of risk for injury) as well as with special populations. The reliability of isometric testing devices has demonstrated varied reliability, generally examining only 1 or 2 motions of the hip and reporting values of force, not torque. Consequently, there is a need for an efficient hip strength-testing device to quantify torque that tests subjects in 1 anatomic position, while evaluating multiple hip motions. Hypothesis: Evaluation of supine hip abduction, adduction, flexion, and extension torque using a new stabilized dynamometer system will produce good to excellent intra- and interexaminer reliability results. Study Design: A blinded, randomized, repeated-measures study design was used in this descriptive laboratory investigation. Methods: Supine isometric hip flexion, extension, abduction, and adduction torques were evaluated with a cage-stabilized dynamometer in 19 collegiate and professional-level ice hockey athletes by 2 investigators at 3 time intervals. Inter- and intrarater reliability was assessed. Results: Supine hip flexion, extension, abduction, and adduction torque was performed with good to excellent inter- and intrarater reliability (intraclass correlation coefficients ranging from 0.74 to 0.92 and 0.78 to 0.92, respectively) for all motions tested. Conclusions: We have developed an isometric hip strength-testing device that can be assembled around an examination table to efficiently and reliably evaluate torque developed for multiple motions of the hip. Clinical Relevance: This device and testing protocol may be used to efficiently evaluate hip strength in numerous settings; it allows decreased subject burden and increased comfort (which may be important following an injury in case-control investigations); and it may be well tolerated when testing athletes as well as special populations in the clinical setting. PMID:24427380

  3. Evaluation of the color stability of two techniques for reproducing artificial irides after microwave polymerization

    PubMed Central

    GOIATO, Marcelo Coelho; dos SANTOS, Daniela Micheline; MORENO, Amália; GENNARI-FILHO, Humberto; PELLIZZER, Eduardo Piza

    2011-01-01

    The use of ocular prostheses for ophthalmic patients aims to rebuild facial aesthetics and provide an artificial substitute to the visual organ. Natural intemperate conditions promote discoloration of artificial irides and many studies have attempted to produce irides with greater chromatic paint durability using different paint materials. Objectives The present study evaluated the color stability of artificial irides obtained with two techniques (oil painting and digital image) and submitted to microwave polymerization. Material and Methods Forty samples were fabricated simulating ocular prostheses. Each sample was constituted by one disc of acrylic resin N1 and one disc of colorless acrylic resin with the iris interposed between the discs. The irides in brown and blue color were obtained by oil painting or digital image. The color stability was determined by a reflection spectrophotometer and measurements were taken before and after microwave polymerization. Statistical analysis of the techniques for reproducing artificial irides was performed by applying the normal data distribution test followed by 2-way ANOVA and Tukey HSD test (α=.05). Results Chromatic alterations occurred in all specimens and statistically significant differences were observed between the oil-painted samples and those obtained by digital imaging. There was no statistical difference between the brown and blue colors. Independently of technique, all samples suffered color alterations after microwave polymerization. Conclusion The digital imaging technique for reproducing irides presented better color stability after microwave polymerization. PMID:21625733

  4. Evaluation of hydrothermal treatment in enhancing rice straw compost stability and maturity.

    PubMed

    Nakhshiniev, Bakhtiyor; Biddinika, Muhammad Kunta; Gonzales, Hazel Bantolino; Sumida, Hiroaki; Yoshikawa, Kunio

    2014-01-01

    In order to evaluate the hydrothermal treatment (HTT) in enhancing compost stability and maturity of lignocellulosic agricultural residues, a bin-scale (90 L) composting of rice straw with and without "HTT" was performed. The rice straw compost product with "HTT" after 6 weeks of composting can be considered stable and adequate for field application as expressed by pH of 8.4, "EC value" of 2.96 dS m(-1), C/N ratio of 12.5, microbial activity of <8.05 mg CO2 g(-1) OM d(-1), NH4(+)-N content of 93.75 mg kg(-1) DM and finally, by "GI" of >83%. However, compost may prove phytotoxic if used as growing media for EC sensitive plants. As for rice straw compost product without "HTT", the high microbial activity (>12.28 mg CO2 g(-1) OM d(-1)) even after 14 weeks of composting suggests that the residue has not stabilized yet and is far away from stability and maturity, although a higher GI (>100%) was observed. PMID:24262840

  5. Soy milk as an emulsifier in mayonnaise: physico-chemical, stability and sensory evaluation.

    PubMed

    Rahmati, Kobra; Mazaheri Tehrani, Mostafa; Daneshvar, Kazem

    2014-11-01

    Mayonnaise is an oil in water emulsion and egg components are its emulsifier. In this research application of soy milk to stabilize mayonnaise was studied. Egg was replaced with full fat soy flour-prepared soy milk at levels of 25, 50, 75, and 100 % and microstructure, stability, color, viscosity and sensory analysis were performed and results were compared with those of control samples containing yolk and whole egg as emulsifier. Results showed that yolk-prepared control (YC) had higher stability and viscosity values and the value of these two attributes decreased as more amounts of soy milk was used. In the case of viscosity there was no statistical difference between soy milk-prepared samples and egg-prepared control (EC) up to 75 % replacement. Color factors changed, which were affected by different proportions of soy milk. Sensory evaluation showed no statistical difference in acceptability of EC and samples with substitution levels up to 50 %. So it can be concluded that egg can be substituted with soy milk in mayonnaise. PMID:26396329

  6. A new method for the evaluation of dental implant stability using an inductive sensor.

    PubMed

    Kim, Dae-Seung; Lee, Woo-Jin; Choi, Soon-Chul; Lee, Sam-Sun; Heo, Min-Suk; Huh, Kyung-Hoe; Kim, Tae-Il; Lee, In-Bog; Han, Jong-Hee; Yi, Won-Jin

    2012-11-01

    We developed a new method for the measurement of dental implant stability by analyzing the impulse response of the implant. The movement of the implant was measured by an inductive sensor with a dedicated adaptor. The large inductance of the adapter amplified the small displacement signal of the implant. The Periotest (Siemens, Bensheim, Germany) was used as a source of excitation force to acquire the impact response of the implant. Power spectrum analysis was applied to the impact response of the implant. The peak frequency of the spectrum was used as a measure of the implant stability. The performance of the system was tested and verified through simulation of the implant-bone interface in an in vitro model. Various implant-bone interfacial conditions were assessed. Holes of varying depth and diameter were drilled into a dental implantation model. Two types of impression materials (EXAMIXFINE, Regisil Rigid) with different degrees of hardness were used to fix the implant into the hole. The implant stability was also measured using the ISQ (implant stability quotient) by resonance frequency analysis on the Osstell Mentor (Integration Diagnostics AB, Goteborgsvagen, Sweden) for comparison. Linear regression analysis of the peak frequency as a stability parameter showed a linear relationship with both the depth and the diameter of the hole (p<0.05). When EXAMIXFINE was used, the peak frequency was linearly associated with the depth (R(2)=0.443) and diameter (R(2)=0.396) of the hole. When Regisil Rigid was used, the peak frequency also showed a linear relationship with the depth (R(2)=0.555) and diameter (R(2)=0.350) of the hole. The peak frequency also increased as the hardness of the impression material increased. Differentiability of the system was evaluated by an ANOVA test. A statistically significant difference (p<0.01) was found between all implantation conditions, except in one case using the Regisil Rigid material. In contrast, the ISQ value did not consistently differentiate under several implantation conditions. The developed method could differentiate the stability changes in simulated implantation conditions with a wider dynamic range and with higher resolution than the ISQ value. PMID:22236553

  7. Evaluation of stability changes in magnesium-incorporated titanium implants in the early healing period.

    PubMed

    Hieu, Pham Duong; Baek, Dong Heon; Park, Dong Soo; Park, Jong-Tae; Hong, Ki Seok

    2013-09-01

    The aim of the present study was to determine the bone response to magnesium (Mg) ion-incorporated titanium (Ti) implants during the early healing period. A total of 114 patients (69 men and 45 women aged between 29 and 71 years) participated in the study. Overall, one hundred thirty-three 10-mm-long fixtures were installed, composed of 65 Mg ion-incorporated fixtures in the test group (55 participants; 30 males and 25 females) and 68 resorbable blast media (RBM) surface fixtures in the control group (59 participants; 39 males and 20 females). The bone responses were evaluated by resonance frequency analysis (RFA) at the following time points after implant insertion (ie, the healing period): 0, 2, 4, 8, and 12 weeks. Each time an RFA measurement was taken, the stability changes relating to both bone quality and implant arch location (maxilla or mandible) were recorded for further analysis. The mean stabilities were lowest at week 4 of healing for both the test and control groups. Significant differences in RFA values between the 2 groups were found at week 12 of healing. The mean percentage change in implant stability quotient (ISQ) from the baseline revealed that the implant stability of the Mg ion-incorporated test group had increased (4.55%) more than the RBM surface group (2.23%) by week 12 of healing. With respect to bone quality, the mean ISQ of Mg-incorporated Ti implants only changed significantly during the 12-week period for type 4 bone. Furthermore, at weeks 4 and 12 of healing, significant differences were found between the 2 groups for type 2 and type 4 bone. A comparison of the stability patterns of mandibular and maxillary implants revealed that the overall stability was higher in the mandible; however, no significant difference was found for Mg-incorporated Ti implants. The Mg-incorporated Ti implants exhibited a slightly better bone response with respect to ISQ than did the RBM surface implants, and the percentage change in mean ISQ from the baseline was greater for the Mg-incorporated group than for the RBM surface group at the end point of this study. PMID:24036725

  8. Monitoring of leachate quality stored in gas ventilation pipes for evaluating the degree of landfill stabilization.

    PubMed

    Tojo, Yasumasa; Sato, Masahiro; Matsuo, Takayuki; Matsuto, Toshihiko

    2011-01-01

    Monitoring of leachate quality is the essential measure in aftercare for evaluating landfill stabilization. Generally, the most common way of leachate monitoring is executed at the inlet of the leachate treatment facility. However, it does not necessarily reflect the actual state of the site. Thus, methodologies which focus on both the discharge, in order to determine when the post-closure care of the facility should terminate, and on the degree of waste stabilization in the landfill are required. In the present study, monitoring of leachate quality stored in 68 gas ventilation pipes was conducted and the degree of waste stabilization at each location in the landfill was estimated by a statistical approach using the results obtained by monitoring. Leachate characteristics varied significantly for each pipe but seemed to reflect the waste condition of the nearby location. Correlation among the analysed items was quite high. Namely, the difference of leachate quality seemed to be categorized only by the level of concentration but not by the specific characteristics. To confirm this, Euclidean distances of dissimilarity were calculated by multidimensional scaling using six items of leachate quality and temperature. Two factors (thickness of leachate and concentration of total organic carbon (TOC) and electric conductivity (EC)) that distinguish leachate characteristics appeared. To indicate the degree of stabilization by location, the spatial distribution of TOC, total nitrogen (TN), inorganic carbon (IC), and chloride ion were estimated by using the ordinary Kriging methodology. As the result, it was estimated that the concentration of leachate existing within the landfill, especially TN, was higher than the completion criteria for leachate in most parts of the investigated area. PMID:20937618

  9. A Review of Methods for Evaluating Particle Stability in Suspension Based Pressurized Metered Dose Inhalers.

    PubMed

    D'Sa, Dexter; Chan, Hak-Kim

    2015-01-01

    Advances in particle engineering techniques, such as spray drying, freeze drying and supercritical fluid precipitation, have greatly enhanced the ability to control the structure, morphology, and solid state phase of inhalable sized particles (1 - 5 µm) for formulation in pressurized metered dose inhalers (pMDI). To optimize the properties of these engineered particles for formulation in hydrofluoroalkane propellants (HFA 134a / 227) it is necessary to measure both bulk and individual particle properties before, after, and during formulation. This review examines established and recently developed methods for evaluating a variety of particle properties including but not limited to size, surface and internal morphology, chemical composition, and solid state phase. Novel methods for evaluating particle physical and chemical stability directly in propellant or similar environments are also discussed. PMID:26290200

  10. Long Term Stability Evaluation of Prostacyclin Released from Biomedical Device Through Turbiscan Lab Expert

    PubMed Central

    Celia, Christian; Locatelli, Marcello; Cilurzo, Felisa; Cosco, Donato; Gentile, Emanuela; Scalise, Daniela; Carafa, Maria; Ventura, Cinzia Anna; Fleury, Mathias; Tisserand, Christelle; Barbacane, Renato C.; Fresta, Massimo; Marzio, Luisa Di; Paolino, Donatella

    2015-01-01

    Therapeutic guidelines indicate prostacyclin as the first line of treatment in inflammation and vascular diseases. Prostacyclins prevent formation of the platelet plug involved in primary hemostasis by inhibiting platelet activation and, combined with thromboxane, are effective vasodilators in vascular damage. Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease II guidelines indicates prostacyclins; in particular, Iloprost, as the first therapeutic option for treating peripheral arterial disease. However, therapeutic efficacy of Iloprost has witnessed several drawbacks that have occurred in patients receiving repeated weekly administration of the drug by intravenous infusions. Adverse reactions arose under perfusion with Iloprost for 6 h and patient compliance was drastically decreased. Biomedical devices could provide a suitable alternative to overcome these drawbacks. In particular, elastomeric pumps, filled with Iloprost isotonic solution, could slowly release the drug, thus decreasing its side effects, representing a valid alternative to hospitalization of patients affected by peripheral arterial disease. However, the home therapy treatment of patients requires long-term stability of Iloprost in solution-loaded elastomeric pumps. The aim of this work was to investigate the long-term stability of Iloprost isotonic solution in biomedical devices using Turbiscan technology. Turbiscan Lab Expert (L’Union, France) predicts the long-term stability of suspensions, emulsions and colloidal formulations by measuring backscattering and transmission of particulates dispersed in solution. The formulations were evaluated by measuring the variation of physical-chemical properties of colloids and suspensions as a function of backscattering and transmission modifications. In addition, the release profile of Iloprost isotonic solution from the biomedical device was evaluated. PMID:25381994

  11. Evaluation of PFP Furnace Systems for Thermal Stabilization of Washed High Chloride Plutonium Oxide Items

    SciTech Connect

    Fischer, Christopher M.; Elmore, Monte R.; Schmidt, Andrew J.; Gerber, Mark A.; Muzatko, Danielle S.; Gano, Susan R.; Thornton, Brenda M.

    2002-12-17

    High chloride content plutonium (HCP) oxides are impure plutonium oxide scrap which contains NaCl, KCl, MgCl2 and/or CaCl2 salts at potentially high concentrations and must be stabilized at 950 C per the DOE Standard, DOE-STD-3013-2000. The chlorides pose challenges to stabilization because volatile chloride salts and decomposition products can corrode furnace heating elements and downstream ventilation components. A high-temperature furnace (same make and model as used at the RMC at Plutonium Finishing Plant) and the associated offgas system were set up at PNNL to identify system vulnerabilities and to investigate alternative materials and operating conditions that would mitigate any corrosion and plugging of furnace and offgas components. The key areas of interest for this testing were the furnace heating elements, the offgas line located inside the furnace, the offgas line between the furnace and the filter/knockout pot, the filter/knockout pot, the sample boat, and corrosion coupons to evaluate alternative materials of construction. The evaluation was conducted by charging the furnace with CeO2 that had been impregnated with a mixture of chloride salts (selected to represent the expected residual chloride salt level in washed high chloride items) and heated in the furnace in accordance with the temperature ramp rates and hold times used at PFP.

  12. Investigations on Substrate Temperature-Induced Growth Modes of Organic Semiconductors at Dielectric/semiconductor Interface and Their Correlation with Threshold Voltage Stability in Organic Field-Effect Transistors.

    PubMed

    Padma, Narayanan; Maheshwari, Priya; Bhattacharya, Debarati; Tokas, Raj B; Sen, Shashwati; Honda, Yoshihide; Basu, Saibal; Pujari, Pradeep Kumar; Rao, T V Chandrasekhar

    2016-02-10

    Influence of substrate temperature on growth modes of copper phthalocyanine (CuPc) thin films at the dielectric/semiconductor interface in organic field effect transistors (OFETs) is investigated. Atomic force microscopy (AFM) imaging at the interface reveals a change from 'layer+island' to "island" growth mode with increasing substrate temperatures, further confirmed by probing the buried interfaces using X-ray reflectivity (XRR) and positron annihilation spectroscopic (PAS) techniques. PAS depth profiling provides insight into the details of molecular ordering while positron lifetime measurements reveal the difference in packing modes of CuPc molecules at the interface. XRR measurements show systematic increase in interface width and electron density correlating well with the change from layer + island to coalesced huge 3D islands at higher substrate temperatures. Study demonstrates the usefulness of XRR and PAS techniques to study growth modes at buried interfaces and reveals the influence of growth modes of semiconductor at the interface on hole and electron trap concentrations individually, thereby affecting hysteresis and threshold voltage stability. Minimum hole trapping is correlated to near layer by layer formation close to the interface at 100 °C and maximum to the island formation with large voids between the grains at 225 °C. PMID:26761590

  13. Investigations on the low voltage cathodoluminescence stability and surface chemical behaviour using Auger and X-ray photoelectron spectroscopy on LiSrBO{sub 3}:Sm{sup 3+} phosphor

    SciTech Connect

    Pitale, Shreyas S.; Nagpure, I.M.; Kumar, Vinay; Ntwaeaborwa, O.M.; Terblans, J.J.; Swart, H.C.

    2011-07-15

    Highlights: {yields} Stable orange-red cathodoluminescence observed from LiSrBO{sub 3}:Sm{sup 3+} phosphor. {yields} In situ Auger electron spectroscopy, while monitoring the CL output reduction, reveals surface concentration modification of Li, Sr, B and O atoms. {yields} X-ray photoelectron spectroscopy confirms the formation of SrO{sub 2} layer due to the electron stimulated surface chemical reactions (ESSCRs). This layer is possibly contributing to the surface chemical stability and prevents further degradation. -- Abstract: Orange-red emissive LiSrBO{sub 3}:Sm{sup 3+} phosphors were synthesized through the solid-state reaction method. Under UV radiation (221 nm) and low-voltage electron beam (2 keV, 12 mA/cm{sup 2}) excitation, the Sm{sup 3+} doped LiSrBO{sub 3} phosphor shows emission corresponding to the characteristic {sup 4}G{sub 5/2}-{sup 6}H{sub 7/2} transitions of Sm{sup 3+} with the strongest emission at 601 nm. A high stability of cathodoluminescence (CL) emission during prolong electron bombardment with low-energy electrons was observed. Surface sensitive diagnostic tools such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to study the surface chemistry. AES results revealed modifications in the surface concentrations of Li, Sr, B, O and C on the surface of the LiSrBO{sub 3}:Sm{sup 3+} phosphor as indicated by the changes in their Auger peak to peak heights (APPH) as a function of electron dose. Observed changes in the high resolution XPS spectra of the LiSrBO{sub 3}:Sm{sup 3+} surface irradiated with the low energy electron beam provide evidence of compositional and structural changes as a result of the electron beam stimulated surface chemical reactions (ESSCRs). Additional SrO{sub 2} was identified by XPS on the phosphor surface after it received an electron dose of 300 C/cm{sup 2} together with the increase in the concentrations of chemical species containing the B-C-O bonding. The new surface chemical species formed during electron beam bombardment are possibly responsible for the stability of the CL in the LiSrBO{sub 3}:Sm{sup 3+} phosphor.

  14. Mine stability evaluation of panel 1 during waste emplacement operations at WIPP

    SciTech Connect

    Maleki, H.

    1998-07-01

    The specific objectives of the work were defined by the Environmental Evaluation Group (EEG) as follows: (1) assess the stability of panel 1 during the proposed operation of waste emplacement; (2) estimate the amount of time before room closure would be expected to transfer rock loads to the waste packages. The work consisted of (1) an analysis of geotechnical data and a review of the Department of Energy`s (DOE) plans for waste emplacement in panel 1, (2) an evaluation of ground conditions based on data analysis and observations of changes in ground conditions since the first evaluation in 1993 (USBM 1993), and (3) preparation of a report and presentation of the results to EEG staff. Excluded from this study are radiological safety issues and policies. The study is based on data provided by DOE and Westinghouse Electric Corporation (operator of the site) and conversations with DOE and Westinghouse personnel. MTI cannot independently verify the accuracy of the data within the scope of this study and recommends independent evaluations of data gathering, quality assurance procedures, and structural designs. The operator has the ultimate responsibility for structural designs and has expressed a strong commitment to ensuring worker safety.

  15. Evaluation of solidification/stabilization technology for Buffalo River sediment. Final report

    SciTech Connect

    Fleming, E.C.; Averett, D.E.; Channell, M.G.; Perry, B.D.

    1991-05-01

    The Buffalo River drains a 446-square-mile (1,155-sq-km) watershed in western New York State and discharges into Lake Erie at the city of Buffalo. The Buffalo River has been classified by the State of New York as a fishing and fish survival stream, but municipal and industrial discharges have degraded the water quality and resulted in a fish advisory for the river. Under the Assessment and Remediation of Contaminated Sediment Program, the US Environmental Protection Agency asked the US Army Corps of Engineers to evaluate solidification/stabilization (S/S) for potential treatment of the contaminated sediments in the Buffalo River. An evaluation of S/S technology was conducted on the bench-scale level on Buffalo River sediment to determine whether physical and chemical properties of the sediment would be improved. Based on analyses of the untreated sediment, five metals were selected for evaluation: chromium, copper, lead, nickel, and zinc. Initial screening tests (ISTs) were conducted on the sediments to narrow the range of binder-to-soil ratios (BSRs) to be prepared in the detailed evaluation.

  16. Power conditioning using dynamic voltage restorers under different voltage sag types

    PubMed Central

    Saeed, Ahmed M.; Abdel Aleem, Shady H.E.; Ibrahim, Ahmed M.; Balci, Murat E.; El-Zahab, Essam E.A.

    2015-01-01

    Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs). By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type. PMID:26843975

  17. Power conditioning using dynamic voltage restorers under different voltage sag types.

    PubMed

    Saeed, Ahmed M; Abdel Aleem, Shady H E; Ibrahim, Ahmed M; Balci, Murat E; El-Zahab, Essam E A

    2016-01-01

    Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs). By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type. PMID:26843975

  18. Transient Voltage Recorder

    NASA Astrophysics Data System (ADS)

    Medelius, Pedro J.; Simpson, Howard J.

    2002-09-01

    A voltage transient recorder can detect lightning induced transient voltages. The recorder detects a lightning induced transient voltage and adjusts input amplifiers to accurately record transient voltage magnitudes. The recorder stores voltage data from numerous monitored channels, or devices. The data is time stamped and can be output in real time, or stored for later retrieval. The transient recorder, in one embodiment, includes an analog-to-digital converter and a voltage threshold detector. When an input voltage exceeds a pre-determined voltage threshold, the recorder stores the incoming voltage magnitude and time of arrival. The recorder also determines if its input amplifier circuits clip the incoming signal or if the incoming signal is too low. If the input data is clipped or too low, the recorder adjusts the gain of the amplifier circuits to accurately acquire subsequent components of the lightning induced transients.

  19. A matter of quantum voltages

    SciTech Connect

    Sellner, Bernhard; Kathmann, Shawn M.

    2014-11-14

    Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. The variation of voltages in matter can be measured by experiment, however, modern supercomputers allow the calculation of accurate quantum voltages with spatial resolutions of bulk systems well beyond what can currently be measured provided a sufficient level of theory is employed. Of particular interest is the Mean Inner Potential (V{sub o}) the spatial average of these quantum voltages referenced to the vacuum. Here we establish a protocol to reliably evaluate V{sub o} from quantum calculations. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of V{sub o} for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Certain aspects in this regard are highlighted making use of simple model systems/approximations. Furthermore, we predict V{sub o} as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms.

  20. A matter of quantum voltages

    NASA Astrophysics Data System (ADS)

    Sellner, Bernhard; Kathmann, Shawn M.

    2014-11-01

    Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. The variation of voltages in matter can be measured by experiment, however, modern supercomputers allow the calculation of accurate quantum voltages with spatial resolutions of bulk systems well beyond what can currently be measured provided a sufficient level of theory is employed. Of particular interest is the Mean Inner Potential (Vo) - the spatial average of these quantum voltages referenced to the vacuum. Here we establish a protocol to reliably evaluate Vo from quantum calculations. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of Vo for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Certain aspects in this regard are highlighted making use of simple model systems/approximations. Furthermore, we predict Vo as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms.

  1. Evaluation of etanercept stability as exposed to various sugars with biophysical assessment.

    PubMed

    Lim, Dae Gon; Kim, Nam Ah; Lim, Jun Yeul; Kim, Ki Hyun; Hada, Shavron; Jeong, Seong Hoon

    2014-12-10

    Even though sugars have been used widely as additives for protein formulations, their exact mechanisms of protein stabilization and applicability remain still in need of investigation. The main purpose of this study was to evaluate the effects of various sugars on the biophysical stability of etanercept (Enbrel(®)). Six well known sugars including glucose, fructose, maltose, sucrose, trehalose, and raffinose were incorporated into the protein solution with different concentrations. The samples were analyzed with dynamic light scattering (DLS), differential scanning calorimetry (DSC), circular dichroism (CD), and size-exclusion chromatography (SEC). The DLS measurement showed that as the number of simple sugars and solution concentration increased, the hydrodynamic size increased with a decreasing absolute zeta potential. The DSC result provided consistent trends with the DLS data. As the concentration of sugar increased, the protein transition temperature (T(m)) was gradually increased in most of samples. In addition, a non-enzymatic browning reaction (NEB) was observed during heating of the sugar solution. To monitor the storage stability, sample solutions were stored at 4 and 40 °C. At 4 °C, the ratio of monomer, aggregate, and fragment were not significantly changed. However, fragmentation of etanercept was observed in accelerated storage. In addition, fructose and maltose showed a peak shift in the SEC result. Those results suggest that the reducing ability of sugar might be a reason for the different etanercept degradation pathways. Therefore, sugars need to be carefully considered to achieve the maximum efficiency of therapeutic proteins for the development of protein formulations. PMID:25269011

  2. Evaluation of Antioxidant Stability of Arbutin and Pyrus boissieriana Buhse Leaf Extract

    PubMed Central

    Khalilpour, Asieh; Pouramir, Mahdi; Asgharpour, Fariba

    2013-01-01

    With regard to the importance of antioxidants in foods, cosmetics and pharmaceutics, there are several studies on natural resources for finding rich sources of antioxidants and their role in protecting the body against oxidative stress injuries. The purpose of this study was to investigate the antioxidant stability of arbutin and the Pyrus boissieriana buhse Leaf extract and their effects on lipid oxidation in different conditions of temperature and time. Arbutin and the Pyrus boissieriana buhse Leaf extract were stored for 14 days in the different conditions of temperature including room, refrigerator and freezer. Total phenolic compounds were measured by the folin-ciocaltea method. Flavonoid compounds were evaluated by aluminum chloride method. Their total antioxidant activity was measured by FRAP (ferric reducing antioxidant power) method and their protection effect on lipid oxidation was measured by TBARS (thiobarbituric acid reactant substances) method. Also, the amount of sustainability for peroxide activities was measured by TMB (Tetra Methyl Benzedrine) method. Polyphenol formed 1.96 mg/g dry weight of Pyrus boissieriana buhse Leaf extract and the amount of flavonoid complex was 0.125 mg/g dry weight of Pyrus boissieriana buhse Leaf extract. The amount of FRAP was decreased by increasing temperature and time. The amount of lipid oxidation had increased in all samples with time (0-14). The stability of peroxide activities decreased in the different conditions of temperature and time. The results of this study show the existence of antioxidant activities with higher stability in storage time and the protective effect of arbutin and Pyrus boissieriana buhse Leaf extract on lipid oxidation. Therefore, using arbutin and Pyrus boissieriana buhse Leaf extract as a natural resource of antioxidant is suggested for substituting synthetic antioxidants. PMID:24551796

  3. Low distortion automatic phase control circuit. [voltage controlled phase shifter

    NASA Technical Reports Server (NTRS)

    Hauge, G.; Pederson, C. W. (Inventor)

    1974-01-01

    A voltage controlled phase shifter is rendered substantially harmonic distortion free over a large dynamic input range by employing two oppositely poled, equally biased varactor diodes as the voltage controlled elements which adjust the phase shift. Control voltages which affect the bias of both diodes equally are used to adjust the phase shift without increasing distortion. A feedback stabilized phase shifter is rendered substantially frequency independent by employing a phase detector to control the phase shift of the voltage controlled phase shifter.

  4. Landslides and slope stability evaluation in the historical town of Kruja, Albania

    NASA Astrophysics Data System (ADS)

    Muceku, Y.; Korini, O.

    2013-07-01

    This paper describes the landslides and slope stability evaluation in the urban area of Kruja town, Albania. Kruja is a~historical and heritage center, due to the existence of many important cultural monuments including Skanderbeg castle and Bazaar square etc. The urban area of Kruja town has been affected from the Landslides effects, in the past and also present. From this phenomenon many engineering objects such as buildings, roads etc. are damaged and demolished. From the engineering geological mapping at scale 1 : 5000 it is observed that many active landslides have dramatically increased in activity after 1980s. The landslide types found in the studied area are earth slides, debris flow, as well as rock fall and rock rolling. Also, from field works and laboratory analysis, the slope stability of whole urban areas has been determined; for this purpose the studied zone is divided into the stable and unstable areas, which helps to better understand the mass movement's activity as one of the most harmful hazards of the geodynamics' phenomena.

  5. Landslide and slope stability evaluation in the historical town of Kruja, Albania

    NASA Astrophysics Data System (ADS)

    Muceku, Y.; Korini, O.

    2014-03-01

    This paper describes landslides and slope stability evaluation in the urban area of Kruja, Albania. Kruja is a historical and heritage center, due to the existence of many important cultural monuments, including "Skanderbeg" castle and Bazaar square, etc. The urban area of Kruja has been affected by landslide effects, in the past and also the present. From this phenomenon many engineering objects such as buildings, roads, etc., are damaged and demolished. From engineering geological mapping at scale 1:5000 it is observed that many active landslides have dramatically increased in activity since the 1980s. The landslide types found in the studied area are earthslides, debris flow, as well as rockfall and rock rolling. Also, from field works and laboratory analysis, the slope stability of the whole urban area has been determined; for this purpose the studied zone is divided into stable and unstable areas, which helps to better understand mass movement activity as one of the most harmful hazards of geodynamic phenomena.

  6. Seismic stability evaluation of Alben Barkley Lock and Dam Project. Volume 1. Summary report. Final report

    SciTech Connect

    Wahl, R.E.; Bluhm, P.F.

    1992-09-01

    This report summarizes the results of seismological, geological, laboratory, field, and analytical investigations conducted to evaluate the seismic stability of two earth embankment sections of the Alben Barkley Lock and Dam Project, Kentucky. These represent typical sections of the powerhouse/switch-yard area and the main embankment. Detailed documentation of each of the major topical areas of this study are contained in Volumes 2 through 5 of this series of reports. The design earthquake, from the New Madrid Seismic Zone, had a body-wave magnitude of 7.5. Of particular interest in this study, was the seismic performance of silty sands in the foundation and their overall effect on the stability of these embankment sections. The results of this study indicate that large scale deformations and/or slope failure which would result in the loss of reservoir are not deformations on the order of 2 to 3 ft are expected. These deformations are relatively small in light of the fact that 28 ft of freeboard are expected to be available during the design earthquake.

  7. Evaluation of different amendments to stabilize antimony in mining polluted soils.

    PubMed

    lvarez-Ayuso, E; Otones, V; Murciego, A; Garca-Snchez, A

    2013-02-01

    Soil pollution with antimony is of increasing environmental concern worldwide. Measures for its control and to attenuate the risks posed to the ecosystem are required. In this study the application of several iron and aluminium oxides and oxyhydroxides as soil amendments was evaluated in order to assess their feasibility to stabilize Sb in mining polluted soils. Mine soils with different pollution levels were amended with either goethite, ferrihydrite or amorphous Al oxide at various ratios (0-10%). The effectiveness of such treatments was assessed by both batch and column leaching tests. The use of ferrihydrite or amorphous Al oxide proved to be highly effective to stabilize Sb. Immobilization levels of 100% were found when doses of 5% ferrihydrite or 10% amorphous Al oxide were applied, regardless of the soil Sb load. Column leaching studies also showed a high Sb leaching reduction (>75%) when soils were amended with 1% ferrihydrite or 5% amorphous Al oxide. Moreover, such treatments proved to simultaneously immobilize As and Pb in a great extent when soils were also polluted with such toxic elements. PMID:23121985

  8. Evaluation of Mungbean Genotypes Based on Yield Stability and Reaction to Mungbean Yellow Mosaic Virus Disease

    PubMed Central

    Alam, AKM Mahbubul; Somta, Prakit; Jompuk, Choosak; Chatwachirawong, Prasert; Srinives, Peerasak

    2014-01-01

    This work was conducted to identify mungbean genotypes showing yield stability and resistance to mungbean yellow mosaic virus (MYMV) disease. Sixteen genotypes were evaluated in a randomized complete block design with two replications for two years (2011 and 2012) at three locations (Gazipur, Ishurdi and Madaripur) of the Bangladesh Agricultural Research Institute. An analysis of variance exhibited significant effects of genotype (G), environment (E), and genotype × environment (G×E) on grain yield. Among eight agronomic characters, the principal component 1 (PC1) was always higher than the PC2. Considering G×E interaction, BM6 was the best genotype at all three locations in both years. Based on grain yield and stability performance, BM6 ranked first while the worst performing genotypes were BM1 and G10. Based on discrimination and representation, Gazipur was identified as an ideal environment for these mungbeans. Relationship between soil-plant analysis developments (SPAD) value was positive with yield but negative with MYMV severity. BM6, G1 and G2 were considered as promising sources of resistance for low disease score and stable response across the environments. The environment proved to have an influence on MYMV infection under natural infestation. A positive correlation was observed between disease score and the temperature under natural growing condition. PMID:25289012

  9. Evaluation of the stability of polymer-based plasmid DNA delivery systems after ultrasound exposure.

    PubMed

    Kuo, Jung-hua Steven; Jan, Ming-shiou; Sung, K C

    2003-05-12

    Under ultrasound exposure, the stability of plasmid DNA protected by polymer-based gene delivery system is an important factor for achieving optimal transfection into cells. We have evaluated the effectiveness of various polymer-based plasmid DNA delivery systems, which are interactive polymers and cationic polymers, to avoid shear degradation induced by ultrasound exposure. Alternatively, it is shown that sonication of plasmid DNA for exposure time as low as 10s resulted in total DNA fragmentation and the loss of transfection potency in NIH/3T3 cells. Among these polymer-based plasmid DNA delivery systems, only cationic polymers had the ability to provide the protection of plasmid DNA from ultrasonic degradation as indicated by the reservation in supercoiled circular (SC) and open circular (OC) forms of plasmid DNA on the agarose gel electrophoresis. The DNA stability protected by cationic polymers decreased after ultrasound exposure in 1M sodium chloride solution. Also, higher molecular weight of cationic polymers and sufficient cationic polymer/DNA weight ratios are essential to prevent DNA from degradation under ultrasound exposure in aqueous or salt solution. These results suggest that the protective mechanism by cationic polymers is due to the attractive bonding between cationic polymer and negative plasmid DNA. Whereas, DNA condensation alone provoked by the addition of polyethylene glycols was not sufficient to resist the DNA fragmentation induced by ultrasound exposure. PMID:12711163

  10. Application of dynamic programming to evaluate the slope stability of a vertical extension to a balefill.

    PubMed

    Kremen, Arie; Tsompanakis, Yiannis

    2010-04-01

    The slope-stability of a proposed vertical extension of a balefill was investigated in the present study, in an attempt to determine a geotechnically conservative design, compliant with New Jersey Department of Environmental Protection regulations, to maximize the utilization of unclaimed disposal capacity. Conventional geotechnical analytical methods are generally limited to well-defined failure modes, which may not occur in landfills or balefills due to the presence of preferential slip surfaces. In addition, these models assume an a priori stress distribution to solve essentially indeterminate problems. In this work, a different approach has been applied, which avoids several of the drawbacks of conventional methods. Specifically, the analysis was performed in a two-stage process: (a) calculation of stress distribution, and (b) application of an optimization technique to identify the most probable failure surface. The stress analysis was performed using a finite element formulation and the location of the failure surface was located by dynamic programming optimization method. A sensitivity analysis was performed to evaluate the effect of the various waste strength parameters of the underlying mathematical model on the results, namely the factor of safety of the landfill. Although this study focuses on the stability investigation of an expanded balefill, the methodology presented can easily be applied to general geotechnical investigations. PMID:20142412

  11. Evaluation of toxic and genotoxic potential of stabilized industrial waste and contaminated soils.

    PubMed

    Bkaert, C; Ferrier, V; Marty, J; Pfohl-Leszkowicz, A; Bispo, A; Jourdain, M J; Jauzein, M; Lambolez-Michel, L; Billard, H

    2002-01-01

    Artificial aqueous samples (eluates, percolates, immersion waters) were obtained from contaminated soils and stabilized industrial wastes. The toxicity and genotoxicity of these aqueous fractions have been evaluated in vivo in the aquatic larvae of the amphibian Xenopus laevis. Four biotests have been applied: a test of subchronic toxicity and three biomakers: (1) measurement of the activity of ethoxyresorufine-o-dealkylase in the liver, (2) detection of DNA adducts in the liver and the blood, and (3) measurement of the rate of micronuclei in the erythrocytes. Biological datas were completed through a chemical analysis. The main conclusions of this study are: The importance of integrating different toxicity criterias into a biological battery (phenotypic and genotypic criterias). Some aqueous extracts did not seem to be very toxic, whereas their genotoxic effects were rather significant [e.g. the stabilized Municipal Solid Waste (MSW) ashes]. The importance of coupling together chemical and biological approaches to refine the impact. Actually, some eluates (lixiviation or percolation) coming from polluted soils appeared to be very poorly loaded with pollutants, whereas the toxic and genotoxic impact of these complex matrices were rather noticeable. In addition, when applying the leaching standardized procedure, the hazardous potential of the two analysed soils may be underestimated if the results on percolates and on eluates have been compared. This study highligths the importance of coupling the tools of characterization and preparation of samples to be analysed according to the objectives to be reached. PMID:12003154

  12. Evaluation of the stability of extemporaneously prepared ophthalmic formulation of mitomycin C.

    PubMed

    Velpandian, Thirumurthy; Saluja, Vinay; Ravi, Alok Kumar; Kumari, Srinivasan Senthil; Mathur, Rajani; Ranjan, Nihar; Ghose, Supriyo

    2005-06-01

    Mitomycin C (MMC) is a cytostatic agent topically used in conjunctival neoplasms, secondary to glaucoma filtering, pterygium, and strabismus surgery to increase the success rate. The topical formulation of MMC for ocular use is always extemporaneously prepared. Our study evaluated the stability of extemporaneously prepared formulations of MMC at different concentrations (150, 300, & 600 microg/mL) kept at different temperatures (25 degrees , 4 degrees , and -70 degrees C) and at different pH range (6, 7, and 8). Aliquots from the above formulations were subjected for quantification of MMC on days 0, 7, 14, 21, and 28 using high-performance liquid chromatography. MMC stored at 25 degrees C for 6 months was also subjected to flow cytometry and compared to freshly prepared MMC. The results indicated that the degradation of MMC is very high in acidic pH at room temperature. Increasing the pH to 7 or 8 and keeping MMC at low temperatures significantly decreased the degradation of MMC. Interestingly, the flow cytometry data revealed that the 6-month-old MMC showed an antiproliferative effect compared to that of freshly prepared MMC. To conclude, the extemporaneously prepared MMC at pH between 7 and 8 and stored in the refrigerator can increase the duration of its stability. However, the antiproliferative study using flow cytometry revealed that degraded MMC retained its activity even after degradation. PMID:15969639

  13. Potential of ultrasonic pulse velocity for evaluating the dimensional stability of oak and chestnut wood.

    PubMed

    Dndar, Trker; Wang, Xiping; As, Nusret; Avc?, Erkan

    2016-03-01

    The objective of this study was to examine the potential of ultrasonic velocity as a rapid and nondestructive method to predict the dimensional stability of oak (Quercus petraea (Mattuschka) Lieblein) and chestnut (Castanea sativa Mill.) that are commonly used in flooring industry. Ultrasonic velocity, specific gravity, and radial, tangential and volumetric shrinkages were measured on seventy-four 202030-mm(3) specimens obtained from freshly cut oak and chestnut stems. The ultrasonic velocities of the specimens decreased with increasing moisture content (MC). We found that specific gravity was not a good predictor of the transverse shrinkages as indicated by relatively weak correlations. Ultrasonic velocity, on the other hand, was found to be a significant predictor of the transverse shrinkages for both oak and chestnut. The best results for prediction of shrinkages of oak and chestnut were obtained when the ultrasonic velocity and specific gravity were used together. The multiple regression models we developed in this study explained 77% of volumetric shrinkages in oak and 72% of volumetric shrinkages in chestnut. It is concluded that ultrasonic velocity coupled with specific gravity can be employed as predicting parameters to evaluate the dimensional stability of oak and chestnut wood during manufacturing process. PMID:26678790

  14. A Preliminary Evaluation of Using Fill Materials to Stabilize Used Nuclear Fuel During Storage and Transportation

    SciTech Connect

    Maheras, Steven J.; Best, Ralph; Ross, Steven B.; Lahti, Erik A.; Richmond, David J.

    2012-08-01

    This report contains a preliminary evaluation of potential fill materials that could be used to fill void spaces in and around used nuclear fuel contained in dry storage canisters in order to stabilize the geometry and mechanical structure of the used nuclear fuel during extended storage and transportation after extended storage. Previous work is summarized, conceptual descriptions of how canisters might be filled were developed, and requirements for potential fill materials were developed. Elements of the requirements included criticality avoidance, heat transfer or thermodynamic properties, homogeneity and rheological properties, retrievability, material availability and cost, weight and radiation shielding, and operational considerations. Potential fill materials were grouped into 5 categories and their properties, advantages, disadvantages, and requirements for future testing were discussed. The categories were molten materials, which included molten metals and paraffin; particulates and beads; resins; foams; and grout. Based on this analysis, further development of fill materials to stabilize used nuclear fuel during storage and transportation is not recommended unless options such as showing that the fuel remains intact or canning of used nuclear fuel do not prove to be feasible.

  15. Evaluation of the postural stability of elderly persons using time domain signal analysis.

    PubMed

    Rasku, Jyrki; Pyykk, Ilmari; Juhola, Martti; Garcia, Melissa; Harris, Tamara; Launer, Lenore; Eiriksdottir, Gudny; Siggeirsdottir, Kristin; Jonsson, Palmi; Hoffman, Howard J; Petersen, Hannes; Rasmussen, Cuno; Caserotti, Paolo; Toppila, Esko; Pajala, Satu; Gudnason, Vilmundur

    2012-01-01

    A force platform is widely used in the evaluation of postural stability in man. Although an abundance of parameters are typically retrieved from force platform data, no uniform analysis of the data has been carried out. In general, the signal analysis does not analyze the underlying postural event, i.e., whether the signal consists of several small corrections or large excursions. In the present work, we studied the postural stability of 4589 elderly persons from Iceland on a force platform under visual and non-visual conditions during stance on a solid surface. We analyzed the internal relationship between frequently used time domain variables. In addition, we conducted a factor analysis using a subset of selected variables. Factor analysis yielded three components that can be considered different strategies for maintaining posture. In one control strategy, long swaying amplitues were pronounced, allowing the person to react when postural confidence limits are reached. In a second strategy, a high oscillation rate about the stationary point was the dominant characteristic of maintaining postural control. The third strategy appears to involve a short critical time period during which an open loop control changes into a closed loop that very rapidly controls excessive postural oscillations. The findings suggest that conventional parameters such as swaying velocity and amplitude alone do not provide sufficient information regarding a person's ability to maintain an upright stance. PMID:23302705

  16. Evaluation of the effectiveness of various amendments on trace metals stabilization by chemical and biological methods.

    PubMed

    Lee, Sang-Hwan; Park, Hyun; Koo, Namin; Hyun, Seunghun; Hwang, Anna

    2011-04-15

    We evaluated the effects of five different kinds of amendments on heavy metals stabilization. The five amendments were: zero valent iron, limestone, acid mine drainage treatment sludge, bone mill, and bottom ash. To determine bioavailability of the heavy metals, different chemical extraction procedures were used such as, extraction with (Ca(NO(3))(2), DTPA; toxic characteristic leaching procedure (TCLP), physiologically based extraction test (PBET) that simulates gastric juice, and sequential extraction test. Bioavailability was also determined by measuring uptake of the heavy metals by lettuce (Lactuca sativa L.) and earthworms (Eisenia fetida). In addition, dehydrogenase activity was measured to determine microbial activity in the soil with the different amendments. The addition of amendments, especially limestone and bottom ash, resulted in a significant reduction in extractable metal contents. Biological assays using lettuce, earthworm, and enzyme activity were found as appropriate indicators of available metal fraction after in situ stabilization of heavy metals. In conclusion, TCLP and sequential extraction test appear to be promising surrogate measure of metal bioavailability in soils for several environment endpoints. PMID:21333442

  17. Stability evaluation of temoporfin-loaded liposomal gels for topical application.

    PubMed

    Dragicevic-Curic, Nina; Winter, Sven; Krajisnik, Danina; Stupar, Mirjana; Milic, Jela; Graefe, Susanna; Fahr, Alfred

    2010-03-01

    Temoporfin (mTHPC) is a potent second-generation synthetic photosensitizer. Topical delivery of mTHPC is of great interest for the photodynamic therapy of psoriasis and superficial skin cancer lesions. The aim of this study was to evaluate the stability of hydrophilic gels containing mTHPC-loaded liposomes. Two different mTHPC-loaded liposome dispersions, composed of 15 % (w/w) nonhydrogenated soybean lecithin of different phosphatidylcholine content, were prepared and incorporated (2:1 w/w) into hydrogels of different carbomer concentrations (1.5, 2.25, and 3%; w/w). Obtained liposomal hydrogels, containing 0.15% (w/w) mTHPC, 10% (w/w) phospholipids, and 0, 0.5, or 1% (w/w) carbomer, were analyzed for flow properties, liposome particle size, and polydispersity index (PDI), pH value, and mTHPC content after their preparation and at predetermined time intervals during 6 months of storage at 4 and 23 degrees C. All hydrogels showed, during the whole period of investigation, adequate characteristics for topical application (i.e., they revealed shear-thinning plastic flow behavior). Rheological parameters, particle size, and PDI of liposomes in hydrogels, mTHPC content, and pH value did not show remarkable changes during the storage of gels, which could make them unacceptable for topical use. The obtained results indicated physical and chemical stability of liposomal gels containing mTHPC during 6 months of storage at both temperatures. PMID:19558347

  18. Use of fluorescence for the high-throughput evaluation of synergistic thermal and photo stabilizer interactions in poly (vinyl chloride)

    SciTech Connect

    Wu Chunyong; Wicks, Douglas A.

    2005-06-15

    The selection of thermal and photo stabilizers for poly (vinyl chloride) (PVC) using conventional methods is a time-consuming process. The high-throughput screening method developed in this research demonstrates rapid and efficient ways to quantify the effectiveness of PVC stabilizers with respect to raw plastic materials, stabilizers, levels of use, and testing conditions. An experimental protocol using liquid sampling and fluorescence measurement was developed to determine the effectiveness of formulations. This was used to evaluate the performance of stabilizers based on the change of fluorescence emission at 440 nm after thermal aging or ultraviolet (UV) radiation. The performance of PVC formulations using six different types of stabilizers was successfully mapped for both PVC resin and flexible PVC.

  19. Hybrid nanosystems based on natural polymers as protein carriers for respiratory delivery: Stability and toxicological evaluation.

    PubMed

    Rodrigues, Susana; Cordeiro, Clara; Seijo, Begoa; Remun-Lpez, Carmen; Grenha, Ana

    2015-06-01

    Chitosan/carrageenan/tripolyphosphate nanoparticles were previously presented as holding potential for an application in transmucosal delivery of macromolecules, with tripolyphosphate demonstrating to contribute for both size reduction and stabilisation of the nanoparticles. This work was aimed at evaluating the capacity of the nanoparticles as protein carriers for pulmonary and nasal transmucosal delivery, further assessing their biocompatibility pattern regarding that application. Nanoparticles demonstrated stability in presence of lysozyme, while freeze-drying was shown to preserve their characteristics when glucose or sucrose were used as cryoprotectants. Bovine serum albumin was associated to the nanoparticles, which were successfully microencapsulated by spray-drying to meet the aerodynamic requirements inherent to pulmonary delivery. Finally, a satisfactory biocompatibility profile was demonstrated upon exposure of two respiratory cell lines (Calu-3 and A549 cells) to the carriers. A negligible effect on cell viability along with no alterations on transepithelial electrical resistance and no induction of inflammatory response were observed. PMID:25843870

  20. A novel photometric method for evaluation of the oxidative stability of virgin olive oils.

    PubMed

    Kamvissis, Vassilis N; Barbounis, Emmanouil G; Megoulas, Nikolaos C; Koupparis, Michael A

    2008-01-01

    The Oxitester method, a novel, simple, and fast photometric method for the evaluation of the antioxidant capacity of olive oils, was validated and compared to the official oil stability index (Rancimat) method. The Oxitester method appeared to be a good alternative to the Rancimat method with adequate correlation for a wide range of virgin olive oil samples, including extrissima virgin olive oils (correlation coefficient 0.88), and extra virgin olive oils of increased acidity (free fatty acids >0.45%, correlation coefficient 0.89). Other quality factors (flavor, free fatty acids content, specific absorbance at 270 and 232 nm, peroxide value, and content of oleic, linoleic, and linolenic acids) were also measured and correlated to the antioxidant capacity values of the Oxitester and Rancimat methods. The Oxitester method, in contrast to the Rancimat method, was indicative of the flavor characteristics of the olive oils and the content of linolenic acid. PMID:18727539

  1. Evaluation of thermal stability of electro-optic polymer by thermally stimulated depolarization current measurement

    NASA Astrophysics Data System (ADS)

    Mo, Xuepeng; Kinemura, Kazuhiko; Yamada, Toshiki; Otomo, Akira; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2014-01-01

    The thermal relaxation process of electro-optic (EO) polymers, Disperse Red 1 (DR1)/poly(methyl methacrylate) (PMMA) guest/host polymer and side-chain copolymer DR1-PMMA (PMMA-co-DR1), was studied using thermally stimulated depolarization current (TSDC) measurement. For the guest/host polymer, two TSDC peaks were identified at temperatures of -50 C (?-peak) and around 100 C (?-peak) due to dipolar depolarization. It was also suggested that the ?-peak is ascribed to disordering of guest DR1 molecules together with randomization of the main body of the PMMA. For the side-chain copolymer, a simple relaxation process of the side-chain DR1 was observed in contrast with the guest/host polymer. Analyzing the TSDC, we estimated the activation energy and relaxation times, and discussed the relaxation mechanisms. Results showed that the TSDC method is available for evaluating the thermal stability of EO polymer.

  2. Use of a general control simulation program to evaluate HVAC control stability

    NASA Astrophysics Data System (ADS)

    Zhang, Xinbang; Warren, M. L.

    1987-08-01

    A general process engineering simulation program for a microcomputer is used to evaluate the response of a cooling system to changes in load, set point, and controller tuning parameters to better understand the control stability of a supply air cooling system used in the Mobile Windows Thermal Test (MoWiTT) Facility. A detailed system model is built out of standard components and is used to plot the steady state performance under different operating conditions. The response of the cooling coil output depends strongly on the transport delays. For a system with a linear control valve, the process gain of the cooling coil increases rapidly as the valve flow fraction decreases. A system which is stable at mid-range is shown to become marginally unstable at the low end of the control range. The application of both an equal percentage valve and reheat are shown to improve the control response of the system under low cooling load conditions.

  3. Using in-process measurements of open-gate structures to evaluate threshold voltage of normally-off GaN-based high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Hou, Bin; Ma, Xiao-Hua; Chen, Wei-Wei; Zhu, Jie-Jie; Zhao, Sheng-Lei; Chen, Yong-He; Xie, Yong; Zhang, Jin-Cheng; Hao, Yue

    2015-10-01

    The parameters of open-gate structures treated with different etching time were monitored during the gate recess process, and their impacts on the threshold voltage (Vth) of final fabricated AlGaN/GaN high electron mobility transistors (HEMTs) based on open-gate structures were discussed in this paper. It is found that Vth can exceed 0 V when channel resistance in the recessed region (Ron-open) increases over 275 ? mm, maximum current (IDmax) decreases below 29 mA/mm, or recessed barrier thickness (tRB) is below 7.5 nm. In addition, tRB obtained by atomic force microscopy measurements and C-V measurements are also compared. Finally, theoretical common criteria based on the experimental results of this work for tRB and Ron-open were established to evaluate the Vth of a regular normally-off AlGaN/GaN HEMTs. The results indicate that these parameters of open-gate structure can be utilized to achieve normally-off HEMTs with controllable Vth.

  4. Unique correlation between non-linear distortion of tangential magnetic field and magnetic excitation voltage - Unexplored ferromagnetic phenomena and their application for ferromagnetic materials evaluation

    NASA Astrophysics Data System (ADS)

    Moorthy, V.

    2016-01-01

    Unexplored ferromagnetic phenomena of non-linear distortion of tangential magnetic field (HT) and that of excitation voltage (VE) across the electromagnetic (EM) yoke, in the presence of a ferromagnetic material between the poles of the EM yoke, have been uniquely correlated in this study. Both the HT and VE show similar distortion behaviour, but in the opposite direction, with unique shape for each ferromagnetic sample with different microstructural conditions. Interestingly unique correlation between (dVE / dt) and (dHT / dt) profiles and their ability to distinguish different magnetisation behaviour of ferromagnetic material with different microstructures have also been discussed in this study. One to one correlation between the distortion of HT and VE shown in this study is clear evidence that both these parameters are strongly influenced by the same mechanism of magnetisation process, but in different ways. The systematic changes in the height and position of the peak and the trough on the time derivative profiles of VE and HT reflect the subtle differences in the magnetisation process for each microstructural condition of the steel. This study reveals the new scientific insight and good potential of this novel as well as very simple approach of distortion analysis of HT and VE for understanding the influence of material properties on the mechanism of magnetisation process and also their suitability for variety of applications related to materials evaluation of ferromagnetic components and structures.

  5. Nondestructive evaluation of orthopaedic implant stability in THA using highly nonlinear solitary waves

    NASA Astrophysics Data System (ADS)

    Yang, Jinkyu; Silvestro, Claudio; Sangiorgio, Sophia N.; Borkowski, Sean L.; Ebramzadeh, Edward; De Nardo, Luigi; Daraio, Chiara

    2012-01-01

    We propose a new biomedical sensing technique based on highly nonlinear solitary waves to assess orthopaedic implant stability in a nondestructive and efficient manner. We assemble a granular crystal actuator consisting of a one-dimensional tightly packed array of spherical particles, to generate acoustic solitary waves. Via direct contact with the specimen, we inject acoustic solitary waves into a biomedical prosthesis, and we nondestructively evaluate the mechanical integrity of the bone-prosthesis interface, studying the properties of the waves reflected from the contact zone between the granular crystal and the implant. The granular crystal contains a piezoelectric sensor to measure the travelling solitary waves, which allows it to function also as a sensor. We perform a feasibility study using total hip arthroplasty (THA) samples made of metallic stems implanted in artificial composite femurs using polymethylmethacrylate for fixation. We first evaluate the sensitivity of the proposed granular crystal sensor to various levels of prosthesis insertion into the composite femur. Then, we impose a sequence of harsh mechanical loading on the THA samples to degrade the mechanical integrity at the stem-cement interfaces, using a femoral load simulator that simulates aggressive, accelerated physiological loading. We investigate the implant stability via the granular crystal sensor-actuator during testing. Preliminary results suggest that the reflected waves respond sensitively to the degree of implant fixation. In particular, the granular crystal sensor-actuator successfully detects implant loosening at the stem-cement interface following violent cyclic loading. This study suggests that the granular crystal sensor and actuator has the potential to detect metal-cement defects in a nondestructive manner for orthopaedic applications.

  6. Evaluation of the stability of a nanoremediation strategy using barley plants.

    PubMed

    Gil-Daz, M; Gonzlez, A; Alonso, J; Lobo, M C

    2016-01-01

    This study evaluated the effectiveness of nZVI in reducing the availability of Cd, Cr or Zn in polluted soils. The influence of this nanoremediation process on the development of barley plants as well as its impact on soil properties and the stability of the metal immobilization afterwards were also evaluated in a greenhouse experiment. The application of nZVI reduced the availability of these metals in the soil, but the effectiveness of the immobilization and its stability depended on the metal chemical characteristics. Cadmium distribution in soil fractions showed an important change after the barley crop, favoring the immobilization of Cd in RS fraction for both nZVI-treated and untreated soils. The Cr immobilization was stable over the time studied and the doses of Cr were lethal for the barley plants. In contrast, the decrease of Cr availability reached after the nZVI treatment induced a reduction of soil phytotoxicity and an improvement in the development of the plants, which were able to complete their growing period. The Zn immobilization with nZVI was stable over time, but its effectiveness was moderate, and the growth of barley plants was poorer than that observed in the cases of Cd and Cr. Thus the best results of metal immobilization with nZVI were obtained for Cr-polluted soils. There was no overall increase of Fe in barley plants from nZVI-treated soils. In relation to the soil, no negative effects on its physico-chemical properties were observed after the time exposure with nZVI. Taking into account these results we can conclude that the use of nZVI is a promising remediation strategy, and its effectiveness would be conditioned to the soil properties and the bioavailable metal concentration. PMID:26431642

  7. Stability evaluation of a rocket engine for gaseous oxygen difluoride (OF2) and gaseous diborane (B2H6) propellants

    NASA Technical Reports Server (NTRS)

    Clayton, R. M.

    1972-01-01

    Results of an experimental evaluation of the dynamic stability of a candidate combustor for the space storable propellants gaseous OF2/B2H6 show that the combustor is unstable without supplementary damping. A computer analysis indicated that the uninhibited engine could be unstable. The experiments, conducted with O2/C2H4 substitute propellants and with 70-30 FLOX/B2H6 (OF2 simulated with FLOX), show that the uninhibited combustor has a low stability margin to starting transient perturbations, but that is relatively insensitive to bomb disturbances. Damping cavities are shown to provide stability.

  8. Automatic voltage imbalance detector

    DOEpatents

    Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

    1984-01-01

    A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

  9. Voltage-gated sodium channels

    PubMed Central

    Abdelsayed, Mena; Sokolov, Stanislav

    2013-01-01

    Epilepsy is a brain disorder characterized by seizures and convulsions. The basis of epilepsy is an increase in neuronal excitability that, in some cases, may be caused by functional defects in neuronal voltage gated sodium channels, Nav1.1 and Nav1.2. The effects of antiepileptic drugs (AEDs) as effective therapies for epilepsy have been characterized by extensive research. Most of the classic AEDs targeting Nav share a common mechanism of action by stabilizing the channels fast-inactivated state. In contrast, novel AEDs, such as lacosamide, stabilize the slow-inactivated state in neuronal Nav1.1 and Nav1.7 isoforms. This paper reviews the different mechanisms by which this stabilization occurs to determine new methods for treatment. PMID:23531742

  10. Mixed voltage VLSI design

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

    A technique for minimizing the power dissipated in a Very Large Scale Integration (VLSI) chip by lowering the operating voltage without any significant penalty in the chip throughput even though low voltage operation results in slower circuits. Since the overall throughput of a VLSI chip depends on the speed of the critical path(s) in the chip, it may be possible to sustain the throughput rates attained at higher voltages by operating the circuits in the critical path(s) with a high voltage while operating the other circuits with a lower voltage to minimize the power dissipation. The interface between the gates which operate at different voltages is crucial for low power dissipation since the interface may possibly have high static current dissipation thus negating the gains of the low voltage operation. The design of a voltage level translator which does the interface between the low voltage and high voltage circuits without any significant static dissipation is presented. Then, the results of the mixed voltage design using a greedy algorithm on three chips for various operating voltages are presented.

  11. Clinical evaluation of accommodation and ocular surface stability relavant to visual asthenopia with 3D displays

    PubMed Central

    2014-01-01

    Background To validate the association between accommodation and visual asthenopia by measuring objective accommodative amplitude with the Optical Quality Analysis System (OQAS®, Visiometrics, Terrassa, Spain), and to investigate associations among accommodation, ocular surface instability, and visual asthenopia while viewing 3D displays. Methods Fifteen normal adults without any ocular disease or surgical history watched the same 3D and 2D displays for 30 minutes. Accommodative ability, ocular protection index (OPI), and total ocular symptom scores were evaluated before and after viewing the 3D and 2D displays. Accommodative ability was evaluated by the near point of accommodation (NPA) and OQAS to ensure reliability. The OPI was calculated by dividing the tear breakup time (TBUT) by the interblink interval (IBI). The changes in accommodative ability, OPI, and total ocular symptom scores after viewing 3D and 2D displays were evaluated. Results Accommodative ability evaluated by NPA and OQAS, OPI, and total ocular symptom scores changed significantly after 3D viewing (p = 0.005, 0.003, 0.006, and 0.003, respectively), but yielded no difference after 2D viewing. The objective measurement by OQAS verified the decrease of accommodative ability while viewing 3D displays. The change of NPA, OPI, and total ocular symptom scores after 3D viewing had a significant correlation (p < 0.05), implying direct associations among these factors. Conclusions The decrease of accommodative ability after 3D viewing was validated by both subjective and objective methods in our study. Further, the deterioration of accommodative ability and ocular surface stability may be causative factors of visual asthenopia in individuals viewing 3D displays. PMID:24612686

  12. Evaluation method of threshold voltage shift of SiC MOSFETs under negative gate bias using n-type SiC MOS capacitors

    NASA Astrophysics Data System (ADS)

    Ohashi, Teruyuki; Iijima, Ryosuke

    2016-02-01

    A novel method for estimating threshold voltage shifts of n-channel SiC MOSFETs under negative gate bias stresses has been proposed. In the proposed method, n-type SiC MOS capacitors were utilized instead of n-channel SiC MOSFETs. The n-type SiC MOS capacitors were exposed to ultraviolet light to generate holes around the gate region at the SiC surfaces. By applying negative gate voltage under this condition, inversion layers of the holes were formed, and negative gate bias stress was applied to the gate oxides of the n-type SiC MOS capacitors. By this method, we investigated the tendency of flat band voltage shifts in SiC MOS capacitors depending on the gate oxide forming condition, and it was confirmed that the tendency is in accord with that of threshold voltage shifts in SiC MOSFETs obtained by the conventional method.

  13. Evaluation of chemical and diastereoisomeric stability of S-adenosylmethionine in aqueous solution by capillary electrophoresis.

    PubMed

    Desiderio, Claudia; Cavallaro, Rosaria A; De Rossi, Antonella; D'Anselmi, Fabrizio; Fuso, Andrea; Scarpa, Sigfrido

    2005-07-01

    Capillary electrophoresis was used for monitoring the stability of S-adenosylmethionine in aqueous solution under different conditions of storage and incubation used for "in vitro" and "in vivo" experiments, by evaluating both the entity of degradation and the possibility of epimerization at the sulfonium group. The determination of S,S-S-adenosylmethionine in presence of its R,S-epimer and degradation products was performed in uncoated capillary of 50 microm ID using 150 mM sodium phosphate buffer at pH 2.5. The analyses were performed in short or long-end injection modes depending if a fast monitoring of the degradation products or the evaluation of the diastereoisomeric ratio were carried out, respectively. In the long-end injection mode the baseline separation of S-adenosylmethionine diastereoisomeric forms and degradation products was obtained in less than 10 min with efficiency values in the range of 172,520-311,439 number of theoretical plates per meter. The results showed that freezing was the optimum storage mode for S-adenosylmethionine aqueous solutions preserving from degradation and diastereoisomeric ratio alterations. Under incubation conditions at 38 degrees C during 14 days period S-adenosylmethionine showed a strong degradation and the formation of three main increasing degradation products. After 7 and 14 days only the 52% and 32% of the initial drug concentration were available and the active S,S-S-adenosylmethionine form was the most affected. PMID:15925246

  14. Evaluation of extra virgin olive oil stability by artificial neural network.

    PubMed

    Silva, Simone Faria; Anjos, Carlos Alberto Rodrigues; Cavalcanti, Rodrigo Nunes; Celeghini, Renata Maria dos Santos

    2015-07-15

    The stability of extra virgin olive oil in polyethylene terephthalate bottles and tinplate cans stored for 6 months under dark and light conditions was evaluated. The following analyses were carried out: free fatty acids, peroxide value, specific extinction at 232 and 270 nm, chlorophyll, L(∗)C(∗)h color, total phenolic compounds, tocopherols and squalene. The physicochemical changes were evaluated by artificial neural network (ANN) modeling with respect to light exposure conditions and packaging material. The optimized ANN structure consists of 11 input neurons, 18 hidden neurons and 5 output neurons using hyperbolic tangent and softmax activation functions in hidden and output layers, respectively. The five output neurons correspond to five possible classifications according to packaging material (PET amber, PET transparent and tinplate can) and light exposure (dark and light storage). The predicted physicochemical changes agreed very well with the experimental data showing high classification accuracy for test (>90%) and training set (>85). Sensitivity analysis showed that free fatty acid content, peroxide value, L(∗)Cab(∗)hab(∗) color parameters, tocopherol and chlorophyll contents were the physicochemical attributes with the most discriminative power. PMID:25722136

  15. Voltage monitoring system

    NASA Technical Reports Server (NTRS)

    Canicatti, C. L. (inventor)

    1975-01-01

    A description is given of a system for monitoring the voltage at a remote location and determining when the voltage exceeds upper and lower levels. The system includes transmission lines for transmitting the voltage back to a central station and applying such to an amplifier having a pair of outputs. One of the outputs of the amplifier is applied to an oscillograph. The other output is fed through an isolation transformer, a full wave rectifier, to a pair of unijunctional transistor circuits for producing pulses when the voltage exceeds or drops below a predetermined level. These pulses, in turn, energize a relay which turns on the oscillograph for recording the voltages being monitored.

  16. Formulation and stability evaluation of extemporaneously prepared atenolol capsules from crushed atenolol tablets.

    PubMed

    Zaid, Abdel Naser; Malkieh, Numan; Kharoaf, Maher; Abu Ghoush, Abeer; Al-Ramahi, Rowa'

    2012-01-01

    The purpose of this study was to formulate a 25-mg atenolol capsule starting from a commercial 100-mg atenolol tablet, given the fact that this strength is not available in Palestine and also because 50-mg atenolol tablets failed the splitting uniformity test of the European Pharmacopoeia, and to evaluate the chemical stability and dissolution behavior of the obtained capsules so as to ensure a high-quality product. A high-performance liquid chromatographic system was used for the analysis and quantification of atenolol in the samples studied. Samples of atenoIol for analysis were prepared as reported by the United States Pharmacopeia monograph. Disintegration and dissolution tests were performed according to the United States Pharmacopeia. The high-performance liquid chromatography assay indicated that the 25-mg atenolol capsules were stable for four months when stored at ambient temperature conditions. The disintegration time for all atenolol capsules was within the United States Pharmacopeia limits of 15 minutes. Atenolol release profile showed that approximately 90% of atenolol dissolved after 10 minutes. This study is important for patients who need to take one half of a 50-mg tablet, but for whom the splitting process doesn't give equal halves, and also for modifying the dose for patients with renal or hepatic problems. Therefore, it is possible for the community pharmacist to crush atenolol 100-mg tablets and refill them in new capsules with each containing a precise amount of atenolol, calculated according to body surface area and kidney and liver functions without affecting the chemical stability of the active ingredient nor its dissolution profile and also have a cost effective dosage form. PMID:23050394

  17. Evaluation of liver tissue damage and grasp stability using finite element analysis.

    PubMed

    Cheng, Lei; Hannaford, Blake

    2016-01-01

    Minimizing tissue damage and maintaining grasp stability are essential considerations in surgical grasper design. Most past and current research analyzing graspers used for tissue manipulation in minimally invasive surgery is based on in vitro experiments. Most previous work assessed tissue injury and grasp security by visual inspection; only a few studies have quantified it. The goal of the present work is to develop a methodology with which to compute tissue damage magnitude and grasp quality that is appropriate for a wide range of grasper-tissue interaction. Using finite element analysis (FEA), four graspers with varying radii of curvature and four graspers with different tooth sizes were analyzed while squeezing and pulling liver tissue. All graspers were treated as surgical steel with linear elastic material properties. Nonlinear material properties of tissue used in the FEA as well as damage evaluation were derived from previously reported in vivo experiments. Computed peak stress, integrated stress, and tissue damage were compared. Applied displacement is vertical and then horizontal to the tissue surface to represent grasp and retraction. A close examination of the contact status of each node within the grasper-tissue interaction surface was carried out to investigate grasp stability. The results indicate less tissue damage with increasing radius of curvature. A smooth wave pattern reduced tissue damage at the cost of inducing higher percentage of slipping area. This methodology may be useful for researchers to develop and test various designs of graspers. Also it could improve surgical simulator performance by reflecting more realistic tissue material properties and predicting tissue damage for the student. PMID:25408249

  18. Evaluation of common organic solvents for gas chromatographic analysis and stability of multiclass pesticide residues.

    PubMed

    Mastovsk, Katerina; Lehotay, Steven J

    2004-06-25

    In this study, we evaluated the suitability of six common organic solvents for gas chromatographic (GC) analysis of pesticides. Three of these, acetone, acetonitrile (MeCN) and ethyl acetate (EtAc), represent extraction solvents commonly used in multiresidue methods for determination of pesticides in produce. The other three, isooctane, hexane and toluene, often serve as exchange solvents before a GC analysis. An ideal solvent for GC analysis of multiclass pesticide residues should be compatible with: the analytes, sample preparation, and GC analysis. This study addresses each aspect with emphasis placed on stability of selected pesticides in the given solvents. In this respect, the exchange solvents proved to be superior to the more polar extraction solvents. Degradation of N-trihalomethylthio fungicides (e.g., captan, folpet, dichlofluanid) in MeCN was observed only in certain lots of the tested MeCN, but even if it occurred, the stability of these analytes as well as that of dicofol and chlorothalonil was dramatically improved by the addition of 0.1% (v/v) acetic acid. Dicofol and chlorothalonil were also unstable in acetone, and pesticides with a thioether group (e.g., fenthion, disulfoton) degraded in the tested EtAc. Formation of isomers of certain pyrethroids (deltamethrin, lambda-cyhalothrin) was recorded in the chromatograms from MeCN and acetone solutions, but this effect more likely occurred during the GC injection than in solution. For several reasons, MeCN was found to be the most suitable solvent for extraction of a wide polarity range of pesticide residues from produce. After acidification, the stability of problematic pesticides in MeCN is acceptable, and MeCN can also serve as a medium for GC injection; therefore solvent exchange is generally not required before GC analysis. If sensitivity is an issue in splitless injection, then toluene was demonstrated to be the best exchange solvent due to its miscibility with MeCN and stronger responses of relatively more polar pesticides (e.g., acephate, methamidophos) as compared to hexane and isooctane. PMID:15230533

  19. 30 CFR 18.47 - Voltage limitation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Voltage limitation. 18.47 Section 18.47 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements 18.47 Voltage limitation. (a)...

  20. Evaluating the efficiency of an asbestos stabilizer on ceiling tiles and the characteristics of the released asbestos fibers.

    PubMed

    Jung, Hyun-Sung; Cha, Jun-Seok; Kim, Seongmi; Lee, Wooseok; Lim, Ho-ju; Kim, Hyunwook

    2015-12-30

    The efficiency of asbestos stabilizers and their adaptability were evaluated by investigating the characteristics of asbestos fibers released from ceiling tiles. The impact of such variables as the wind speed or vibration conditions was also studied along with the asbestos stabilizers. The concentrations of the asbestos fibers released from damaged ceiling tiles treated with stabilizers decreased by 69.5-84.4% compared with those of untreated tiles for all variables, with a statistically significant difference (p<0.001). The effects of the environmental factors on the asbestos concentrations were analyzed through a multiple regression analysis. It was determined that the surface status of the ceiling tiles and stabilizers were the main factors affecting the concentration, and the reliability of these factors was estimated as 58.3%. The lengths of the chrysotile fibers released from the damaged ceiling tiles were in the range of 0.991-79.1 ?m for the untreated tiles and 3.74-35.6 ?m for the tiles treated with inorganic stabilizers. It was confirmed that inorganic stabilizers are more efficient for damaged ceiling tiles. The results of this study also show that the asbestos concentrations are greatly reduced after treating damaged ceiling tiles with a stabilizer. PMID:26218305

  1. Technical evaluation report (Revision 1) on the proposed design modifications and technical specification changes on grid voltage degradation for the Peach Bottom Atomic Power Station, Units 2 and 3

    SciTech Connect

    Selan, J.C.

    1983-03-11

    This report is a revision of the technical evaluation documented in a separate report dated November 3, 1981 (UCID-19115) on the proposed design modification and Technical Specification changes for the protection of the Class 1E equipment from grid voltage degradation for the Peach Bottom Atomic Power Station, Units 2 and 3. The review criteria are based on several IEEE standards and The Code of Federal Regulations. The evaluation compares the submittals made by the plant with the NRC staff positions and the review criteria. The evaluation finds that the proposed design modifications and the required changes to the Technical Specifications will ensure that the Class 1E equipment will be protected from sustained voltage degradation.

  2. Bioremediation of Contaminated Lake Sediments and Evaluation of Maturity Indicies as Indicators of Compost Stability

    PubMed Central

    Rekha, P.; Suman Raj, D. S.; Aparna, C.; Bindu, V. Hima; Anjaneyulu, Y.

    2005-01-01

    Land contamination is one of the widely addressed problems, which is gaining importance in many developed and developing countries. International efforts are actively envisaged to remediate contaminated sites as a response to adverse health effects. Popular conventional methodologies only transfer the phase of the contaminant involving cost intensive liabilities besides handling risk of the hazardous waste. Physico-chemical methods are effective for specific wastes, but are technically complex and lack public acceptance for land remediation. Bioremediation, is one of the emerging low-cost technologies that offer the possibility to destroy various contaminants using natural biological activities. Resultant non -toxic end products due to the microbial activity and insitu applicability of this technology is gaining huge public acceptance. In the present study, composting is demonstrated as a bioremediation methodology for the stabilization of contaminated lake sediments of Hyderabad, A.P, India. Lake sediment contaminated with organics is collected from two stratums upper (0.25 m) and lower (0.5m) to set up as Pile I (Upper) and Pile II (Lower) in the laboratory. Lime as a pretreatment to the lake sediments is carried out to ensure metal precipitation. The pretreated sediment is then mixed with organic and inorganic fertilizers like cow dung, poultry manure, urea and super phosphate as initial seeding amendments. Bulking agents like sawdust and other micronutrients are provided. Continuous monitoring of process control parameters like pH, moisture content, electrical conductivity, total volatile solids and various forms of nitrogen were carried out during the entire course of the study. The stability of the compost was evaluated by assessing maturity indices like C/N, Cw (water soluble carbon), CNw (Cw/Nw), nitrification index (NH4/NO?3), Cation Exchange Capacity (CEC), germination index, humification ratio, compost mineralization index (ash content/oxidizable carbon), sorption capacity index (CEC/oxidizable carbon). Enzyme activities of agricultural interest like urease, phosphatase, ?-glucosidase, dehydrogenase and BAA-hydrolyzing protease, which are involved in the nitrogen, phosphorus and carbon cycles, were also assessed. Total content of macro and micronutrients in the final compost was also determined to assess the fertilizer value. The studies revealed that composting could be applied as a remediation technology after removing the top sediment. The maturity indices that are evaluated from the present study can be used to validate the success of the remediation technology. PMID:16705825

  3. Bioremediation of contaminated lake sediments and evaluation of maturity indicies as indicators of compost stability.

    PubMed

    Rekha, P; Suman Raj, D S; Aparna, C; Hima Bindu, V; Anjaneyulu, Y

    2005-08-01

    Land contamination is one of the widely addressed problems, which is gaining importance in many developed and developing countries. International efforts are actively envisaged to remediate contaminated sites as a response to adverse health effects. Popular conventional methodologies only transfer the phase of the contaminant involving cost intensive liabilities besides handling risk of the hazardous waste. Physico-chemical methods are effective for specific wastes, but are technically complex and lack public acceptance for land remediation. iBioremediatio n, is one of the emerging low-cost technologies that offer the possibility to destroy various contaminants using natural biological activities. Resultant non-toxic end products due to the microbial activity and insitu applicability of this technology is gaining huge public acceptance. In the present study, composting is demonstrated as a bioremediation methodology for the stabilization of contaminated lake sediments of Hyderabad, A.P, India. Lake sediment contaminated with organics is collected from two stratums--upper (0.25 m) and lower (0.5m) to set up as Pile I (Upper) and Pile II (Lower) in the laboratory. Lime as a pretreatment to the lake sediments is carried out to ensure metal precipitation. The pretreated sediment is then mixed with organic and inorganic fertilizers like cow dung, poultry manure, urea and super phosphate as initial seeding amendments. Bulking agents like sawdust and other micronutrients are provided. Continuous monitoring of process control parameters like pH, moisture content, electrical conductivity, total volatile solids and various forms of nitrogen were carried out during the entire course of the study. The stability of the compost was evaluated by assessing maturity indices like C/N, Cw (water soluble carbon), CNw (Cw/Nw), nitrification index (NH4/NO-3), Cation Exchange Capacity (CEC), germination index, humification ratio, compost mineralization index (ash content/oxidizable carbon), sorption capacity index (CEC/oxidizable carbon). Enzyme activities of agricultural interest like urease, phosphatase, P-glucosidase, dehydrogenase and BAA-hydrolyzing protease, which are involved in the nitrogen, phosphorus and carbon cycles, were also assessed. Total content of macro and micronutrients in the final compost was also determined to assess the fertilizer value. The studies revealed that composting could be applied as a remediation technology after removing the top sediment. The maturity indices that are evaluated from the present study can be used to validate the success of the remediation technology. PMID:16705825

  4. Does surface roughness influence the primary stability of acetabular cups? A numerical and experimental biomechanical evaluation.

    PubMed

    Le Cann, Sophie; Galland, Alexandre; Rosa, Benot; Le Corroller, Thomas; Pithioux, Martine; Argenson, Jean-Nol; Chabrand, Patrick; Parratte, Sbastien

    2014-09-01

    Most acetabular cups implanted today are press-fit impacted cementless. Anchorage begins with the primary stability given by insertion of a slightly oversized cup. This primary stability is key to obtaining bone ingrowth and secondary stability. We tested the hypothesis that primary stability of the cup is related to surface roughness of the implant, using both an experimental and a numerical models to analyze how three levels of surface roughness (micro, macro and combined) affect the primary stability of the cup. We also investigated the effect of differences in diameter between the cup and its substrate, and of insertion force, on the cups' primary stability. The results of our study show that primary stability depends on the surface roughness of the cup. The presence of macro-roughness on the peripheral ring is found to decrease primary stability; there was excessive abrasion of the substrate, damaging it and leading to poor primary stability. Numerical modeling indicates that oversizing the cup compared to its substrate has an impact on primary stability, as has insertion force. PMID:25080896

  5. High-voltage power supply with improved thermostability for Xenon gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Petrenko, D.; Uteshev, Z.; Novikov, A.; Shustov, A.; Vlasik, K.; Chernysheva, I.; Smirnova, M.; Krivova, K.; Dmitrenko, V.; Ulin, S.

    2016-02-01

    In this article the high voltage power supply for xenon spectrometer is described. Result of time simulation for output voltage at different temperatures was shown. The experimental data is confirming results of the time simulations. The experimental data showed breadboard model provides a stability of voltage better than 1% of the generated voltage at different temperatures

  6. BICUVOX.1-matrix composite electrolyte with yttria-stabilized zirconia as an inert phase: SEM evaluation of the chemical stability under hydrogen atmosphere.

    PubMed

    Piva, R H; Piva, D H; Venturini, J; Floriano, R; Morelli, M R

    2015-01-01

    The purpose of this study is to evaluate the efficacy of yttria-stabilized zirconia (3Y-TZP) as an inert phase to prevent the decomposition of Bi2 V0.9 Cu0.1 O5.5 -δ (BICUVOX.1) electrolyte under reducing atmosphere. A post-mortem scanning electron microscopy (SEM) study was performed after chemical stability tests under hydrogen-rich atmosphere using a Sieverts-type apparatus. SEM results showed that BICUVOX.1 decomposition starts under a hydrogen pressure of 19.7 atm at 300°C, even in the case of the composite containing 3Y-TZP. The microstructure of BICUVOX.1 after decomposition was observed to be composed of microspheres ranging from 10 to 100 µm formed primarily of metallic bismuth. In the composite, in addition to microspheres, the microstructure contained bismuth fibers growth from the grain area of the BICUVOX.1 matrix. Despite significant surface morphological modifications, the grain-boundary-arranged 3Y-TZP particles in a BICUVOX.1-matrix composite did not result in enhanced chemical stability. PMID:25940790

  7. Stability evaluation of the Panel 1 rooms and the E140 drift at WIPP

    SciTech Connect

    Maleki, H.; Chaturvedi, L.

    1996-08-01

    WIPP, intended for underground permanent disposal of defense transuranic waste, is located 40 km east of Carlsbad at a depth of 655 m in the salt beds of the 600-m thick Permian Salado Formation. It will consist of 56 ``rooms`` each 91.5 m long, 10 m wide, and 4 m high, grouped in 8 ``panels`` of 7 rooms each. About 7.5 km of access drifts will also be provided. Excavation began in 1982 and surface/access/test facilities and one panel were completed by 1988, many years before it could be used. Current plans are to start emplacing waste in WIPP in 1998 and continue for 35 years. The north- south drift E140 is the widest (25 ft) of the four main north-south drifts and is the main north-south passage. Plans to conduct experiments with waste in 1993 were abandoned, and the plan now is to use panel 1 for permanent disposal of waste starting in 1998. The stability evaluation resulted in the conclusion that, while it would be possible to safely use portions of panel 1 for waste emplacement, it would be best to abandon panel 1 and mine a new panel after the decision has been made to use WIPP as a repository and the necessary permits obtained.

  8. Immediate release tablets of telmisartan using superdisintegrant-formulation, evaluation and stability studies.

    PubMed

    Sekar, Vasanthakumar; Chellan, Vijaya Raghavan

    2008-04-01

    Telmisartan (anti-hypertensive) is insoluble in water; hence the drug may be slowly or incompletely dissolved in the gastro intestinal tract. So the rate of dissolution and therefore its bioavailability is less (bioavailability 42%). In the present study an attempt has been made to prepare immediate release tablets of telmisartan by using Polyplasdone XL-10 (Crosspovidone) at intragranular, extragranular and partly intra and extragranular level of addition to increase the rate of drug release from dosage form to increase the dissolution rate and hence its bioavailability. The prepared granules and tablets were evaluated for their physiochemical properties and in-vitro dissolution study was conducted for the prepared tablets. It was concluded that the immediate release tablets with proper hardness, disintegration time and with increase rate of dissolution can be made using Polyplasdone XL-10. Formuation-10 (F10) was selected for stability study and the in-vitro dissolution study showed that was no difference in percent of drug released between initial and sixth month sample. PMID:18379110

  9. Evaluation of the thermal stability POHC incinerability ranking in a pilot-scale rotary kiln incinerator

    SciTech Connect

    Lee, J.W.; Waterland, L.R.; Whitworth, W.E.; Carroll, G.J.

    1991-01-01

    A series of pilot-scale incineration tests was performed at EPA's Incineration Research Facility to evaluate the thermal stability-based POHC incinerability ranking. In the tests, mixtures of 12 POHCs with predicted incinerability spanning the range of most to least difficult to incinerate class were combined with a clay-based sorbent and batch-fed to the facility's pilot-scale rotary kiln incinerator via a fiberpack drum ram feeder. Kiln operating conditions were varied to include a baseline operating condition, three modes of attempted incineration failure, and a worst case combination of the three failure modes. Kiln exit POHC DREs were in the 99.99 percent range for the volatile POHCs for the baseline, mixing failure (increased charge mass), and matrix failure (decreased feed H/C) tests. Semivolatile POHCs were not detected in the kiln exit for these tests; corresponding DREs were generally greater than 99.999 percent. The thermal failure (low kiln temperature) and worst case (combination of thermal, mixing, and matrix failure) tests resulted in substantially decreased kiln exit POHC DREs. These ranged from 99 percent or less for Freon 113 to greater than 99.999 percent for the less stable-ranked semivolatile POHCs. General agreement between relative kiln exit POHC DRE and predicted incinerability class was observed.

  10. Pilot-scale evaluation of the thermal-stability POHC incinerability anking

    SciTech Connect

    Lee, J.W.; Whitworth, W.E.; Waterland, L.R.

    1992-04-01

    A test series were performed at the U.S. EPA Incineration Research Facility (IRF) to evaluate the thermal-stability-based principal organic hazardous constituent (POHC) incinerability ranking. Mixtures of twelve POHCs with predicted incinerabilities spanning the range of most- to least-difficult-to-incinerate classes were combined with a clay-based sorbent matrix and fed to the facility's pilot-scale rotary kiln incinerator. Kiln operating conditions were varied to include a baseline operating condition, three modes of attempted incineration failure, and a worst-case combination of the three failure modes. Kiln-exit POHC destruction and removal efficiencies (DREs) were in the 99.99% range for the volatile POHCs during the baseline, mixing failure and matrix failure tests. Semivolatile POHCs were not detected at the kiln exit for these tests; corresponding DREs were generally greater than 99.999%. The thermal failure and worst-case tests resulted in substantially decreased kiln-exit POHC DREs, ranging from less than 99% to greater than 99.999%. General agreement between measured and predicted relative kiln-exit POHC DREs was observed for those two tests.

  11. Stability Evaluation Of Previous Volcanic Edifice Collapse At Pico De Orizaba Volcano, Mexico, Using Geotechnical Techniques

    NASA Astrophysics Data System (ADS)

    Concha-Dimas, A.; Watters, R. J.

    2001-12-01

    Pico de Orizaba volcano has collapsed twice during its geologic evolution (Carrasco-Nuñez, 1997). The initial stage of evolution for this volcano is known as the Torrecillas cone that collapsed 0.21 Ma b.p., and the related deposits formed the Jamapa avalanche which traveled eastward 75 km. A second, superimposed constructional stage is the Espolón de Oro cone that also ended with a collapse 20 000 years b.p., forming the Tetelzingo avalanche-lahar that traveled 85 km. Samples from the remains of old summit cores and their corresponding collapse deposits were collected and tested in order to obtain strength parameters of altered rock from old volcanic edifices. Hydrothermal alteration and variations of strength of the two avalanche deposits were correlated with the strength values and alterations from the in situ corresponding sources. Strength values: Hoek and Brown's parameters, Uniaxial Compressive Strength (50-300 kPa), cohesion (480-2000 kPa), angle of friction (6° - 35° ); and degree of alteration give insights of rock mass quality and maximum intact rock strengths of the edifice rock mass. These values provide the upper limits for numerical model input parameter values for evaluation of flank stability. Rock strength from numerical model of previous failures can be compared with those obtained for the rock mass and intact rock of the actual edifice. This would permit the assessment of future avalanche hazards.

  12. Comparison of methods for evaluating the thermal stability of human enteric viruses.

    PubMed

    Arthur, Sabastine E; Gibson, Kristen E

    2015-03-01

    Human enteric viruses have been identified as one of the predominant causative agents of food-borne illnesses in developed countries, and it is estimated that human norovirus accounts for a majority of these illnesses each year. Not all of these viruses can be cultured and hence relatively little is known about their pathogenesis and physicochemical properties. To overcome this, researchers have utilized different virus surrogates for the study of non-cultivable human enteric viruses. In this review, we discuss various methods utilized for the evaluation of the thermal stability of human enteric viruses, compare the results of these methods, and examine how researchers may move toward a single standard approach (i.e., temperatures, virus concentrations, volume/weight of matrices, etc.) for determining thermal inactivation profiles of human enteric viruses and their surrogates. Based on our review, we found that temperature, time of exposure, type of matrix, analysis type, type of heat application, and the concentration and volume of virus used in the experiments were highly variable across virus surrogates even for the same surrogates. Because of these differences-along with the inherent limitations of using surrogate viruses-comparison of these methods and how the results may be extrapolated to human enteric viruses is quite challenging. As a result, we discuss how researchers may move toward a single standard approach for determining thermal inactivation profiles of human enteric viruses and their surrogates. PMID:25526719

  13. Evaluation of crystallinity and film stress in yttria-stabilized zirconia thin films

    SciTech Connect

    Piascik, Jeffrey R.; Thompson, Jeffrey Y.; Bower, Christopher A.; Stoner, Brian R.

    2005-09-15

    Yttria (3 mol %)-stabilized zirconia (YSZ) thin films were deposited using radio frequency (rf) magnetron sputtering. The YSZ thin films were deposited over a range of temperatures (22-300 deg. C), pressures (5-25 mTorr), and gas compositions (Ar/O ratio). Initial studies characterized a select set of properties in relation to deposition parameters including: refractive index, structure, and film stress. X-ray diffraction (XRD) showed that the films are comprised of mainly monoclinic and tetragonal crystal phases. The film refractive index determined by prism coupling, depends strongly on deposition conditions and ranged from 1.959 to 2.223. Wafer bow measurements indicate that the sputtered YSZ films can have initial stress ranging from 86 MPa tensile to 192 MPa compressive, depending on the deposition parameters. Exposure to ambient conditions (25 deg. C, 75% relative humidity) led to large increase ({approx}100 MPa) in the compressive stress of the films. Environmental aging suggests the change in compressive stress was related to water vapor absorption. These effects were then evaluated for films formed under different deposition parameters with varying density (calculated packing density) and crystal structure (XRD)

  14. In Vitro Evaluation of Dimensional Stability of Alginate Impressions after Disinfection by Spray and Immersion Methods

    PubMed Central

    Hamedi Rad, Fahimeh; Ghaffari, Tahereh; Safavi, Sayed Hamed

    2010-01-01

    Background and aims The most common method for alginate impression disinfection is spraying it with disinfecting agents, but some studies have shown that these impressions can be immersed, too. The aim of this study was to evaluate the dimensional stability of alginate impressions following disinfecting by spray and immersion methods. Materials and methods Four common disinfecting agents (Sodium Hypochlorite, Micro 10, Glutaraldehyde and De-conex) were selected and the impressions (n=108) were divided into four groups (n=24) and eight subgroups (n=12) for disinfecting by any of the four above-mentioned agents by spray or immersion methods. The control group (n=12) was not disinfected. Then the impressions were poured by type III Dental Stone Plaster in a standard method. The results were ana-lyzed by descriptive methods (mean and standard deviation), t-test, two-way analysis of variance (ANOVA) and Duncan test, using SPSS 14.0 software for windows. Results The mean changes of length and height were significant between the various groups and disinfecting methods. Regarding the length, the greatest and the least amounts were related to Deconex and Micro 10 in the immersion method, respectively. Regarding height, the greatest and the least amounts were related to Glutaraldehyde and Deconex in the im-mersion method, respectively. Conclusion Disinfecting alginate impressions by Sodium Hypochlorite, Deconex and Glutaraldehyde by immersion method is not recommended and it is better to disinfect alginate impressions by spraying of Micro 10, Sodium Hypochlorite, Glutaraldehyde and immersion in Micro 10. PMID:23346340

  15. INTERNATIONAL WASTE TECHNOLOGIES EVALUATION REPORT SITE PROGRAM DEMONSTRATION, IN-SITU STABILIZATION/SOLIDIFICATION, HIALEAH, FL, VOLUME I

    EPA Science Inventory

    A demonstration of the International Waste Technologies (IWT) process, utilizing the Geo-Con, Inc., deep-soil-mixing equipment has been performed under the Superfund Innovative Technology Evaluation (SITE) Program. his was the first field demonstration of an in situ stabilization...

  16. EVALUATION OF TWO LEAD-BASED PAINT REMOVAL AND WASTE STABILIZATION TECHNOLOGY COMBINATIONS ON TYPICAL EXTERIOR SURFACES: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-1624 Daniels*, A., Kominsky, J.R., and Clark*, P.J. Evaluation of Two Lead-Based Paint Removal and Waste Stabilization Technology Combinations on Typical Exterior Surfaces. Published in: Journal of Hazardous Materials 87 (1-3):117-126 (2001). 10/04/2001 A study was co...

  17. Enhanced cycling stability and rate performance of Li[Ni0.5Co0.2Mn0.3]O2 by CeO2 coating at high cut-off voltage

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Yang, Gao-Li; Dong, Yue; Shi, Ting; Chen, Li

    2015-05-01

    A rough coating structure of CeO2@Li[Ni0.5Co0.2Mn0.3]O2 can be formed via a wet chemical method. X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectroscope (EDS) are carried out to study the structures and morphologies, which all confirm the existence of CeO2 coating layer on the Li[Ni0.5Co0.2Mn0.3]O2 surface. The 2 wt.% CeO2-coated Li[Ni0.5Co0.2Mn0.3]O2 can deliver 97.4 mAh g-1 at 10 C and 59.2 mAh g-1 at 20 C after 100 cycles in the voltage range of 2.8-4.6 V, while the pristine Li[Ni0.5Co0.2Mn0.3]O2 can deliver only 23.5 mAh g-1 at 10 C and 9.0 mAh g-1 at 20 C. The discharge capacities of CeO2-coated Li[Ni0.5Co0.2Mn0.3]O2 samples at high discharge rates are much higher than those of the pristine Li[Ni0.5Co0.2Mn0.3]O2. Meanwhile, the CeO2-coated Li[Ni0.5Co0.2Mn0.3]O2 sample shows better rate performance at different rates. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements reveal that the improved electrochemical performance can be attributed to the reduced interfacial polarization and stabilized structure of Li[Ni0.5Co0.2Mn0.3]O2 by CeO2 coating. Transmission electron microscope (TEM) is applied to analyze the role of CeO2 coating layer on the long cycling life.

  18. Role of primary stability for successful osseointegration of dental implants: Factors of influence and evaluation

    PubMed Central

    Ahmed, Hameeda Bashir; Crespi, Roberto; Romanos, Georgios E.

    2013-01-01

    A secure implant primary (mechanical) stability is positively associated with a successful implant integration and long-term successful clinical outcome. Therefore, it is essential to assess the initial stability at different time-points to ensure a successful osseointegration. The present study critically reviews the factors that may play a role in achieving a successful initial stability in dental implants. Databases were searched from 1983 up to and including October 2013 using different combinations of various keywords. Bone quality and quantity, implant geometry, and surgical technique adopted may significantly influence primary stability and overall success rate of dental implants. PMID:24381734

  19. Evaluating network analysis and agent based modeling for investigating the stability of commercial air carrier schedules

    NASA Astrophysics Data System (ADS)

    Conway, Sheila Ruth

    For a number of years, the United States Federal Government has been formulating the Next Generation Air Transportation System plans for National Airspace System improvement. These improvements attempt to address air transportation holistically, but often address individual improvements in one arena such as ground or in-flight equipment. In fact, air transportation system designers have had only limited success using traditional Operations Research and parametric modeling approaches in their analyses of innovative operations. They need a systemic methodology for modeling of safety-critical infrastructure that is comprehensive, objective, and sufficiently concrete, yet simple enough to be deployed with reasonable investment. The methodology must also be amenable to quantitative analysis so issues of system safety and stability can be rigorously addressed. The literature suggests that both agent-based models and network analysis techniques may be useful for complex system development and analysis. The purpose of this research is to evaluate these two techniques as applied to analysis of commercial air carrier schedule (route) stability in daily operations, an important component of air transportation. Airline-like routing strategies are used to educe essential elements of applying the method. Two main models are developed, one investigating the network properties of the route structure, the other an Agent-based approach. The two methods are used to predict system properties at a macro-level. These findings are compared to observed route network performance measured by adherence to a schedule to provide validation of the results. Those interested in complex system modeling are provided some indication as to when either or both of the techniques would be applicable. For aviation policy makers, the results point to a toolset capable of providing insight into the system behavior during the formative phases of development and transformation with relatively low investment. Both Agent-Based Modeling and Network Analysis were found to be useful in this context, particularly when applied with an eye towards the system context, and concentrated effort on capturing the salient features of the system of interest.

  20. Hyphenation of a Deoxyribonuclease I immobilized enzyme reactor with liquid chromatography for the online stability evaluation of oligonucleotides.

    PubMed

    Álvarez Porebski, Piotr Wiktor; Gyssels, Ellen; Madder, Annemieke; Lynen, Frederic

    2015-11-27

    The stability of antisense oligonucleotides (ONs) toward nucleases is a key aspect for their possible implementation as therapeutic agents. Typically, ON stability studies are performed off-line, where the ONs are incubated with nucleases in solution, followed by their analysis. The problematics of off-line processing render the detailed comparison of relative ON stability quite challenging. Therefore, the development of an online platform based on an immobilized enzyme reactor (IMER) coupled to liquid chromatography (LC) was developed as an alternative for improved ON stability testing. More in detail, Deoxyribonuclease I (DNase I) was immobilized on epoxy-silica particles of different pore sizes and packed into a column for the construction of an IMER. Subsequently, the hyphenation of the IMER with ion-pair chromatography (IPC) and ion-exchange chromatography (IEC) was evaluated, leading to the successful development of two online methodologies: IMER-IPC and IMER-IEC. More specifically, natural and modified DNA and RNA oligonucleotides were used for testing the performance of the methodologies. Both methodologies proved to be simple, automatable, fast and highly reproducible for the quantitative and qualitative evaluation of ON degradation. In addition, the extended IMER life time in combination with a more straightforward control of the reaction kinetics substantiate the applicability of the IMER-LC platform for ON stability tests and its implementation in routine and research laboratories. PMID:26515385

  1. Parenteral oil-based drospirenone microcrystal suspensions-evaluation of physicochemical stability and influence of stabilising agents.

    PubMed

    Nippe, Stefanie; General, Sascha

    2011-09-15

    Drospirenone (DRSP) is a contraceptive drug substance with challenging physicochemical properties, due to insufficient solubility in aqueous and oil-based vehicles as well as low chemical stability in aqueous fluids. Although it is one of the most popular orally used progestins, no parenteral long-acting contraceptive containing the drug substance is marketed. An oil-based DRSP microcrystal suspension (MCS) might be an attractive formulation option. The main focus of this study was to investigate the physicochemical stability of such preparations. Moreover, syringeability and injectability via autoinjector were analysed using a materials testing machine. A high chemical stability of DRSP was found in oil-based vehicles. Span() 83, cholesteryl oleate, lecithin, methyl cholate, Aerosil() R972 and 200 Pharma were tested for increasing the physical stability of DRSP dispersions. Changes in viscosity, rheological properties, and solubility were analysed. The intention was to show a stabilising effect of the excipients without increasing viscosity and solubility. To evaluate the physical stability of DRSP MCS with and without addition of stabilising agents, sedimentation and particle growth after storage were examined. Especially, the silica derivatives Aerosil() 200 and R972 Pharma influenced the physical stability positively. PMID:21729745

  2. Freeze-dried whole plasma: evaluating sucrose, trehalose, sorbitol, mannitol and glycine as stabilizers.

    PubMed

    Bakaltcheva, Irina; O'Sullivan, Anne Marie; Hmel, Peter; Ogbu, Helen

    2007-01-01

    Several groups report stability results for freeze-dried whole plasma intended for use as a transfusion product [Hellstern P, Sachse H, Schwinn H, Oberfrank K. Manufacture and in vitro characterization of a solvent/detergent-treated human plasma. Vox Sang 1992;63:178-185; Trobisch H. Results of a quality-control study of lyophilized pooled plasmas which have been virally inactivated using a solvent detergent method (modified Horowitz procedure). Beitr Infusionsther 1991;28:92-109; Hugler P, Trobish H, Neuman H, Moller, Sirtl C, Derdak M, Laubenthal H. Quality control of three different conventional fresh-frozen plasma preparations and one new virus-inactivated lyophilized pooled plasma preparation. Klin Wochenschr 1991;69:157-161; Krutvacho T, Chuansumrit A, Isarangkura P, Pintadit P, Hathirat P, Chiewsilp P. Response of hemophilia with bleeding to fresh dry plasma. Southeast Asian J Trop Med Public Health 1993;24:169-173; Chuansumrit A, Krasaesub S, Angchaisuksiri P, Hathirat P, Isarangkura P. Survival analysis of patients with haemophilia at the International Haemophilia Training Centre, Bangkok, Thailand. Haemophilia 2004;10:542-549]. Plasma coagulation properties are substantially impaired in these freeze-dried plasmas, while pH levels are close to alkaline. In this work, plasma supplemented with 60mM sucrose, trehalose, mannitol, sorbitol or glycine was freeze-dried. The samples were subjected to forced degradation at 40 degrees C for 10 days in order to quickly evaluate the effectiveness of the different stabilizers. Initial PT, APTT and TT values were 14.4+/-0. 5s, 31.4+/-1.5s and 18.3+/-0.6s, respectively. At the end of the degradation period, PT, APTT and TT were substantially prolonged, and were 19.1+/-0. 5s, 43.1+/-0.6s and 26.1+/-1.0s, respectively. In the presence of glycine, at the end of the degradation period, PT, APTT and TT values remained close to the initial values and were 15.5+/-0. 4s, 35.7+/-0.9s and 19.4+/-0.2s, respectively. Percent activities of the coagulation factors V, VII, VIII, IX, X and the coagulation inhibitors protein C, protein S and antithrombin III were recorded. Factors V and VIII were most prone to degradation. Factor V and VIII activities, in control plasma, were approx. 44+/-3.5% and 58+/-2.3%, at the end of storage. In contrast, much higher factor V and VIII activities were maintained in the lyophilized glycine-supplemented plasma: approx. 60+/-3.5% and 74+/-7.0%, correspondingly. The most stable protein was protein C, which showed no signs of degradation under the testing conditions of this study. All tested stabilizers provided protection. Glycine, however, outperformed all tested polyols, providing superior preservation of plasma clotting properties. Thermograms of 60mM glycine in water and 60mM glycine in plasma show that, in the presence of plasma, glycine does not crystallize. The process of freeze-drying caused a complete loss of plasma pCO(2) (gas) and a substantial increase in plasma pH. Citric acid was found to be a suitable pH adjuster for lyophilized/rehydrated plasma. PMID:16962645

  3. Evaluation of an iterative model–based reconstruction algorithm for low-tube-voltage (80 kVp) computed tomography angiography

    PubMed Central

    Noël, Peter B.; Köhler, Thomas; Fingerle, Alexander A.; Brown, Kevin M.; Zabic, Stanislav; Münzel, Daniela; Haller, Bernhard; Baum, Thomas; Henninger, Martin; Meier, Reinhard; Rummeny, Ernst J.; Dobritz, Martin

    2014-01-01

    Abstract. The objective of this study was to investigate the improvement in diagnostic quality of an iterative model–based reconstruction (IMBR) algorithm for low-tube-voltage (80-kVp) and low-tube-current in abdominal computed tomography angiography (CTA). A total of 11 patients were imaged on a 256-slice multidetector computed tomography for visualization of the aorta. For all patients, three different reconstructions from the low-tube-voltage data are generated: filtered backprojection (FBP), IMBR, and a mixture of both IMBR+FBP. To determine the diagnostic value of IMBR-based reconstructions, the image quality was assessed. With IMBR-based reconstructions, image noise could be significantly reduced, which was confirmed by a highly improved contrast-to-noise ratio. In the image quality assessment, radiologists were able to reliably detect more third-order and higher aortic branches in the IMBR reconstructions compared to FBP reconstructions. The effective dose level was, on average, 3.0 mSv for 80-kVp acquisitions. Low-tube-voltage CTAs significantly improve vascular contrast as presented by others; however, this effect in combination with IMBR enabled yet another substantial improvement of diagnostic quality. For IMBR, a significant improvement of image quality and a decreased radiation dose at low-tube-voltage can be reported. PMID:26158054

  4. EFFECTS OF PYRETHROIDS ON VOLTAGE-SENSITIVE CALCIUM CHANNELS: A CRITICAL EVALUATION OF STRENGTHS, WEAKNESSES, DATA NEEDS, AND RELATIONSHIP TO ASSESSMENT OF CUMULATIVE NEUROTOXICITY.

    EPA Science Inventory

    A recently published review (Soderlund et al., 2002, Toxicology 171, 3-59.) of the mechanisms of acute neurotoxicity of pyrethroid compounds postulated that voltage-sensitive calcium channels (VSCC) may be a target of some pyrethroid compounds and that effects on VSCC may contrib...

  5. Interfacial degradation effects of aqueous solution-processed molybdenum trioxides on the stability of organic solar cells evaluated by a differential method

    SciTech Connect

    Lou, Yan-Hui; Wang, Zhao-Kui E-mail: lsliao@suda.edu.cn; Yuan, Da-Xing; Liao, Liang-Sheng E-mail: lsliao@suda.edu.cn; Okada, Hiroyuki

    2014-09-15

    The authors investigate the influence of two hole interfacial materials poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) and aqueous solution-processed MoO{sub 3} (sMoO{sub 3}) on cell stability. sMoO{sub 3}-based device demonstrated obviously improved stability compared to PEDOT:PSS-based one. Current-voltage characteristics analysis is carried out to investigate the effect of the hole interfacial layers on the cell stability. The formation of additional trap states at the interfaces between the hole interfacial layer and the active layer in degraded devices is verified by a differential method. Improved cell stability is attributed to a relatively stable sMoO{sub 3} interfacial layer compared to PEDOT:PSS by comparing their different trap states distributions.

  6. Improving Low Voltage Ride Through Capability of Wind Generators Using Dynamic Voltage Restorer

    NASA Astrophysics Data System (ADS)

    Sivasankar, Gangatharan; Suresh Kumar, Velu

    2014-08-01

    The increasing wind power integration with power grid has forced the situation to improve the reliability of wind generators for stable operation. One important problem with induction generator based wind farm is its low ride through capability to the grid voltage disturbance. Any disturbance such as voltage dip may cause wind farm outages. Since wind power contribution is in predominant percentage, such outages may lead to stability problem. The proposed strategy is to use dynamic voltage controller (DVR) to compensate the voltage disturbance. The DVR provides the wind generator the ability to remain connected in grid and improve the reliability. The voltage dips due to symmetrical and unsymmetrical faults are considered for analysis. The vector control scheme is employed for fault compensation which uses software phase locked loop scheme and park dq0 transformation technique. Extensive simulation results are included to illustrate the control and operation of DVR.

  7. Montezuma Creek Stability Evaluation at Site of Former Monticello Tailings Pile

    SciTech Connect

    Korte, N.

    2001-10-04

    This report documents the results of an evaluation of stream stability for Montezuma Creek downstream of the former uranium and vanadium millsite at Monticello, Utah. The work was performed by personnel from Oak Ridge National Laboratory's (ORNL's) Environmental Technology Section (ETS). ORNL/ETS was the Independent Verification Contractor (IVC) for the Monticello projects, and it established independent verification strategies that provided the U.S. Department of Energy (DOE) with a third-party assessment of whether remedial action had effectively reduced levels of contamination and whether supporting documentation that described the remediation was adequate. The DOE regulation 10 CFR 1022, which implements Executive Orders 11988 and 11990 for the protection of wetlands and floodplains, provided the regulatory rationale for the activity. This report documents both the impact of millsite remedial activities and postremediation conditions of Montezuma Creek. The scientific rationale for the stream survey was that conventional engineering practices do not adequately account for varying hydrologic regimes nor do they address the entire riparian zone as an interrelated unit. As a result, modifications to streams consistently cause damage to the environment by increasing erosion and sedimentation. Field activities included the establishment of permanent cross sections and periodic measurements and surveys of physical characteristics. The data demonstrated an increase in downstream stream bank erosion when activities at the millsite were greatest. Note, however, that agricultural practices have also contributed to erosion and bank instability. Nevertheless, an increase in fine sediment and bank recession were correlated to the construction. In addition, the project documented the failure of best management practices such as silt fences, to control sediment loss. Furthermore, conventional engineering designs were used to reroute Montezuma Creek, an action that will require increased maintenance when compared to a natural channel. Although these latter actions remain the most common practices, it is recommended that DOE apply geomorphic designs at future sites.

  8. Development and evaluation of suspension plasma sprayed yttria stabilized zirconia coatings as thermal barriers

    NASA Astrophysics Data System (ADS)

    van Every, Kent J.

    The insulating effects from thermal barrier coatings (TBCs) in gas turbine engines allow for increased operational efficiencies and longer service lifetimes. Consequently, improving TBCs can lead to enhanced gas turbine engine performance. This study was conducted to investigate if yttria-stabilized zirconia (YSZ) coatings, the standard industrial choice for TBCs, produced from nano-sized powder could provide better thermal insulation than current commericial YSZ coatings generated using micron-sized powders. The coatings for this research were made via the recently developed suspension plasma spraying (SPS) process. With SPS, powders are suspended in a solvent containing dispersing agents; the suspension is then injected directly into a plasma flow that evaporates the solvent and melts the powder while transporting it to the substrate. Although related to the industrial TBC production method of air plasma spraying (APS), SPS has two important differences---the ability to spray sub-micron diameter ceramic particles, and the ability to alloy the particles with chemicals dissolved in the solvent. These aspects of SPS were employed to generate a series of coatings from suspensions containing 100 nm diameter YSZ powder particles, some of which were alloyed with neodymium and ytterbium ions from the solvent. The SPS coatings contained columnar structures not observed in APS TBCs; thus, a theory was developed to explain the formation of these features. The thermal conductivity of the coatings was tested to evaluate the effects of these unique microstructures and the effects of the alloying process. The results for samples in the as-sprayed and heat-treated conditions were compared to conventional YSZ TBCs. This comparison showed that, relative to APS YSZ coatings, the unalloyed SPS samples typically exhibited higher as-sprayed and lower heat-treated thermal conductivities. All thermal conductivity values for the alloyed samples were lower than conventional YSZ TBCs. The different thermal conduction behaviors were linked to the porosity and compositional properties of the coatings using immersion density, SEM, and synchrotron radiation characterization techniques.

  9. Solubilization of beclomethasone dipropionate in sterically stabilized phospholipid nanomicelles (SSMs): physicochemical and in vitro evaluations

    PubMed Central

    Sahib, Mohanad Naji; Abdulameer, Shaymaa Abdalwahed; Darwis, Yusrida; Peh, Kok Khiang; Tan, Yvonne Tze Fung

    2012-01-01

    Background The local treatment of lung disorders such as asthma and chronic obstructive pulmonary disease via pulmonary drug delivery offers many advantages over oral or intravenous routes of administration. This is because direct deposition of a drug at the diseased site increases local drug concentrations, which improves the pulmonary receptor occupancy and reduces the overall dose required, therefore reducing the side effects that result from high drug doses. From a clinical point of view, although jet nebulizers have been used for aerosol delivery of water-soluble compounds and micronized suspensions, their use with hydrophobic drugs has been inadequate. Aim: To evaluate the feasibility of sterically stabilized phospholipid nanomicelles (SSMs) loaded with beclomethasone dipropionate (BDP) as a carrier for pulmonary delivery. Methods 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly(ethylene glycol 5000) polymeric micelles containing BDP (BDP-SSMs) were prepared by the coprecipitation and reconstitution method, and the physicochemical and in vitro characteristics of BDP-SSMs were investigated. Results BDP-SSMs were successfully prepared with a content uniformity and reproducibility suitable for pulmonary administration. The maximum solubility of BDP in SSMs was approximately 1300 times its actual solubility. The particle size and zeta potential of BDP-SSMs were 19.89 0.67 nm and ?28.03 2.05 mV, respectively. The SSMs system slowed down the release of BDP and all of the aerodynamic values of the aerosolized rehydrated BDP-SSMs were not only acceptable but indicated a significant level of deposition in the lungs. Conclusion The SSM system might be an effective way of improving the therapeutic index of nebulized, poorly soluble corticosteroids. PMID:22393583

  10. Voltage verification unit

    DOEpatents

    Martin, Edward J. (Virginia Beach, VA)

    2008-01-15

    A voltage verification unit and method for determining the absence of potentially dangerous potentials within a power supply enclosure without Mode 2 work is disclosed. With this device and method, a qualified worker, following a relatively simple protocol that involves a function test (hot, cold, hot) of the voltage verification unit before Lock Out/Tag Out and, and once the Lock Out/Tag Out is completed, testing or "trying" by simply reading a display on the voltage verification unit can be accomplished without exposure of the operator to the interior of the voltage supply enclosure. According to a preferred embodiment, the voltage verification unit includes test leads to allow diagnostics with other meters, without the necessity of accessing potentially dangerous bus bars or the like.

  11. Study of second phase in bioabsorbable magnesium alloys: Phase stability evaluation via Dmol{sup 3} calculation

    SciTech Connect

    Yang, Huazhe; Liu, Chen; Wan, Peng; Tan, Lili; Yang, Ke

    2013-11-01

    Thermodynamical stabilities of four conventional second phases as well as magnesium matrix in bioabsorbable magnesium alloys were investigated theoretically via computer calculation method. Model of individual phase and systems including phase and four water molecular (phase-4H{sub 2}O) were established to simulate the in vitro and in vivo environment. Local orbital density functional theory approach was applied to calculate the total energy for the individual phase and phase-4H{sub 2}O system. The results demonstrated that all the second phases possessed higher phase stability compared with magnesium matrix, but the phase stability was quite different for different types of second phases or second phase-4H{sub 2}O systems. Furthermore, a schematic process of inflammation reaction caused by magnesium alloy implants was proposed for the further evaluation on biocompatibility of different second phases.

  12. Evaluation of physical stability and leachability of Portland pozzolona cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants.

    PubMed

    Patel, Hema; Pandey, Suneel

    2012-03-15

    The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland pozzolona cement (PPC) was selected as the binder system which is commercially available cement with 10-25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62-33.62 MPa) and block density (1222.17-1688.72 kg/m3) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications. PMID:21724323

  13. A simple method for precisely evaluating the stability regions of a multi-mode laser

    NASA Astrophysics Data System (ADS)

    Jahanpanah, J.; Baiat, S.

    2014-10-01

    We recently introduced a heuristic method for delimiting the stability regions of a three-mode class A laser with three freedom degrees. Here this method is extended to cover the stability conditions of a three-mode class B laser with five freedom degrees. The diagonal arrays of the stability coefficient determinant are taken equal to zero until the determinant vanishes. It then turns out that the diagonal roots correspond to the laser stability boundaries. They form the different kinds of bifurcations that segregate the above-threshold state, with three simultaneous oscillating modes, from the bistability and below-threshold states, with two and no oscillating modes, respectively. The fast optical switches and high optical memories have been designed by exploiting the bistability properties of bifurcations as reported by Perez et al (2007 Opt. Express 15 12941-8).

  14. Evaluation of Laser Stabilization and Imaging Systems for LCLS-II - Oral Presentation

    SciTech Connect

    Barry, Matthew

    2015-08-19

    This presentation covers data collected on two commercial laser stabilization systems, Guidestar-II and MRC, and two optical imaging systems. Additionally, general information about LCLS-II and how to go about continuing-testing is covered.

  15. TECHNOLOGY EVALUATION REPORT: SITE PROGRAM DEMONSTRATION TEST, SOLIDITECH, INC. SOLIDIFICATION/STABILIZATION PROCESS VOL II

    EPA Science Inventory

    The primary objective of the Soliditech, Inc. solidification/stabilization demonstration was to develop reliable performance and cost information. he demonstration took palce at the Imperial Oil Company/Champion Chemical Company Superfund site in Morganiville, New Jersey. ontamin...

  16. TECHNOLOGY EVALUATION REPORT: SITE PROGRAM DEMONSTRATION TEST, SOLIDITECH, INC. SOLIDIFICATION/STABILIZATION PROCESS VOL I

    EPA Science Inventory

    The primary objective of the Soliditech, Inc. solidification/stabilization demonstration was to develop reliable performance and cost information. he demonstration took palce at the Imperial Oil Company/Champion Chemical Company Superfund site in Morganiville, New Jersey. Contami...

  17. International Comparative Evaluation of Knee Replacement with Fixed or Mobile Non-Posterior-Stabilized Implants

    PubMed Central

    Namba, Robert; Graves, Stephen; Robertsson, Otto; Furnes, Ove; Stea, Susanna; Puig-Verdi, Lluis; Hoeffel, Daniel; Cafri, Guy; Paxton, Elizabeth; Sedrakyan, Art

    2014-01-01

    Background: Mobile-bearing total knee prostheses were designed to reduce wear and improve implant survivorship following total knee arthroplasty. However, the benefit of mobile-bearing total knee arthroplasty remains unproven. Both mobile-bearing and fixed-bearing total knee arthroplasty implants are available in posterior-stabilized and non-posterior-stabilized designs. With the latter, the implant does not recreate the function of the posterior cruciate ligament (PCL) with a posterior-stabilizing cam mechanism. The purpose of the present study was to compare mobile-bearing, non-posterior-stabilized devices with fixed-bearing, non-posterior-stabilized devices used in total knee arthroplasty through a novel multinational study design. Methods: Through the use of a distributed health data network, primary total knee arthroplasties performed for osteoarthritis from 2001 to 2010 were identified from six national and regional total joint arthroplasty registries. Multivariate meta-analysis was performed with use of linear mixed models, with the primary outcome of interest being revision for any reason. Survival probabilities and their standard errors were extracted from each registry for each unique combination of the covariates. Results: A total of 319,616 patients (60% female) underwent non-posterior-stabilized total knee arthroplasty. A fixed-bearing, non-posterior-stabilized design was used in 258,190 (81%) of the knees and a mobile-bearing, non-posterior-stabilized design in 61,426 (19%) of the knees. Sixty-nine percent of the patients who received a fixed-bearing implant were over sixty-five years of age, compared with 63% of those who received a mobile-bearing implant. Mobile-bearing designs had a higher risk of revision, with a hazard ratio of 1.43 (95% confidence interval, 1.36 to 1.51; p < 0.001). Conclusions: Previous comparisons of mobile-bearing and fixed-bearing total knee arthroplasty outcomes have been inconclusive. The current study utilized an advanced, harmonized distributed analysis of six national and regional joint-replacement registries. To our knowledge, it is the largest analysis of mobile-bearing total knee arthroplasty to date. Mobile-bearing, non-posterior-stabilized designs presented a greater risk of failure than was found for fixed-bearing, non-posterior-stabilized designs. Caution should be used in the selection of the mobile-bearing non-posterior-stabilized design for total knee replacement. PMID:25520419

  18. Dissipative performance of dielectric elastomers under various voltage waveforms.

    PubMed

    Zhang, Junshi; Li, Bo; Chen, Hualing; Pei, Qibing

    2016-02-17

    The actuation performance of dielectric elastomers (DEs) is affected by dissipation. In the present article, an analytical model is developed to investigate the dissipative performance of DEs by considering viscoelasticity and leakage current. Various voltage waveforms, such as DC voltage, square voltage, stepwise DC voltage, ramp voltage, sawtooth voltage, and triangular voltage, were applied to explore the dissipative performance of DEs. The DEs with diverse moduli and viscoelasticity intensities were also analyzed by comparing the different dissipative performances. Numerical calculations were employed to evaluate the dissipative behavior of DEs. When the value of the applied voltage is maintained invariable, the stretch gradually creeps, and the total current from the battery and the leakage current approach each other eventually. When the applied voltage varies linearly, the stretch deforms dramatically, and then the total current from the battery is much larger than the leakage current. PMID:26791085

  19. Economic evaluation of flying-qualities design criteria for a transport configured with relaxed static stability

    NASA Technical Reports Server (NTRS)

    Sliwa, S. M.

    1980-01-01

    Direct constrained parameter optimization was used to optimally size a medium range transport for minimum direct operating cost. Several stability and control constraints were varied to study the sensitivity of the configuration to specifying the unaugmented flying qualities of transports designed to take maximum advantage of relaxed static stability augmentation systems. Additionally, a number of handling qualities related design constants were studied with respect to their impact on the design.

  20. Mass spectrometric evaluation of neuropeptidomic profiles upon heat stabilization treatment of neuroendocrine tissues in crustaceans.

    PubMed

    Sturm, Robert M; Greer, Tyler; Woodards, Nicole; Gemperline, Erin; Li, Lingjun

    2013-02-01

    Tissue heat stabilization is a vital component in successful mammalian neuropeptidomic studies. Heat stabilization using focused microwave irradiation, conventional microwave irradiation, boiling, and treatment with the Denator Stabilizor T1 have all proven effective in arresting post-mortem protein degradation. Although research has reported the presence of protein fragments in crustacean hemolymph when protease inhibitors were not added to the sample, the degree to which post-mortem protease activity affects neuropeptidomic tissue studies in crustacean species has not been investigated in depth. This work examines the need for Stabilizor T1 or boiling tissue stabilization methods for neuropeptide studies of Callinectes sapidus (blue crab) pericardial organ tissue. Neuropeptides in stabilized and nonstabilized tissue were extracted using acidified methanol or N,N-dimethylformamide (DMF) and analyzed by MALDI-TOF and nanoLC-ESI-MS/MS platforms. Post-mortem fragments did not dramatically affect MALDI analysis in the range m/z 650-1600, but observations in ESI MS/MS experiments suggest that putative post-mortem fragments can mask neuropeptide signal and add spectral complexity to crustacean neuropeptidomic studies. The impact of the added spectral complexity did not dramatically affect the number of detected neuropeptides between stabilized and nonstabilized tissues. However, it is prudent that neuropeptidomic studies of crustacean species include a preliminary experiment using the heat stabilization method to assess the extent of neuropeptide masking by larger, highly charged molecular species. PMID:23227893

  1. Kinetic resistive wall mode stability evaluation and physics insight application in NSTX

    NASA Astrophysics Data System (ADS)

    Berkery, J.; Sabbagh, S.; Betti, R.; Bell, R.; Diallo, A.; Gerhardt, S.; Leblanc, B.; Menard, J.; Podesta, M.

    2014-10-01

    Research on the National Spherical Torus Experiment (NSTX) has studied the stability of resistive wall modes (RWMs) in high-beta fusion plasmas for disruption avoidance. Stabilizing mechanisms for RWMs have been identified as the transfer of energy from the mode to thermal particles through rotational resonances and the effect of energetic particles to resist distortion of the magnetic field lines. These kinetic effects have been implemented in the MISK '' code and results have compared favorably with NSTX experiments including prediction of the marginal stability point and agreement with the trends of low-frequency MHD spectroscopy experiments. Further improvement of the already close agreement of MISK '' to experimental results is being pursued by comparison to a large database of NSTX discharges and implementation of additional physics in the code, including rotational effects on the fluid stability and the effect of pressure anisotropy. An ITPA MHD Stability Group joint analysis task verified several kinetic RWM codes, including MISK '', and generally good agreement between the codes was achieved. A new disruption avoidance algorithm in NSTX-Upgrade will utilize the knowledge gained by kinetic stability physics insight, calculation, and comparison with experiment. This research was supported by the U.S. Department of Energy under Contracts DE-FG02-99ER54524, DE-AC02-09CH11466, and DE-FG02-93ER54215.

  2. Technical evaluation of the proposed design modifications and technical specification changes on grid voltage degradation (Part A) for the Peach Bottom Atomic Power Station, Units 2 and 3: selected issues program (Docket Nos. 50-277, 50-278)

    SciTech Connect

    White, R. L.

    1981-11-03

    This report documents the technical evaluation of the proposed design modification and Technical Specification changes for protection of Class 1E equipment from grid voltage degradation for the Peach Bottom Atomic Power Station, Units 2 and 3. The review criteria are based on several IEEE standards and The Code of Federal Regulations. The evaluation compares the submittals made by the plant with the NRC staff positions and the review criteria. The licensee meets the requirements of the NRC except for the submittal of proposed Technical Specification changes to substantiate the proposed circuit modifications and relay setpoints.

  3. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, Fang Zheng (Oak Ridge, TN); Lai, Jih-Sheng (Knoxville, TN)

    1997-01-01

    A voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means.

  4. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, F.Z.; Lai, J.S.

    1997-07-01

    Disclosed is a voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means. 15 figs.

  5. International Comparative Evaluation of Knee Replacement with Fixed or Mobile-Bearing Posterior-Stabilized Prostheses

    PubMed Central

    Graves, Stephen; Sedrakyan, Art; Baste, Valborg; Gioe, Terence J.; Namba, Robert; Cruz, Olga Martnez; Stea, Susanna; Paxton, Elizabeth; Banerjee, Samprit; Isaacs, Abby J.; Robertsson, Otto

    2014-01-01

    Background: Posterior-stabilized total knee prostheses were introduced to address instability secondary to loss of posterior cruciate ligament function, and they have either fixed or mobile bearings. Mobile bearings were developed to improve the function and longevity of total knee prostheses. In this study, the International Consortium of Orthopaedic Registries used a distributed health data network to study a large cohort of posterior-stabilized prostheses to determine if the outcome of a posterior-stabilized total knee prosthesis differs depending on whether it has a fixed or mobile-bearing design. Methods: Aggregated registry data were collected with a distributed health data network that was developed by the International Consortium of Orthopaedic Registries to reduce barriers to participation (e.g., security, proprietary, legal, and privacy issues) that have the potential to occur with the alternate centralized data warehouse approach. A distributed health data network is a decentralized model that allows secure storage and analysis of data from different registries. Each registry provided data on mobile and fixed-bearing posterior-stabilized prostheses implanted between 2001 and 2010. Only prostheses associated with primary total knee arthroplasties performed for the treatment of osteoarthritis were included. Prostheses with all types of fixation were included except for those with the rarely used reverse hybrid (cementless tibial and cemented femoral components) fixation. The use of patellar resurfacing was reported. The outcome of interest was time to first revision (for any reason). Multivariate meta-analysis was performed with linear mixed models with survival probability as the unit of analysis. Results: This study includes 137,616 posterior-stabilized knee prostheses; 62% were in female patients, and 17.6% had a mobile bearing. The results of the fixed-effects model indicate that in the first year the mobile-bearing posterior-stabilized prostheses had a significantly higher hazard ratio (1.86) than did the fixed-bearing posterior-stabilized prostheses (95% confidence interval, 1.28 to 2.7; p = 0.001). For all other time intervals, the mobile-bearing posterior-stabilized prostheses had higher hazard ratios; however, these differences were not significant. Conclusions: Mobile-bearing posterior-stabilized prostheses had an increased rate of revision compared with fixed-bearing posterior-stabilized prostheses. This difference was evident in the first year. PMID:25520420

  6. Approach to evaluating dried blood spot sample stability during drying process and discovery of a treated card to maintain analyte stability by rapid on-card pH modification.

    PubMed

    Liu, Guowen; Ji, Qin C; Jemal, Mohammed; Tymiak, Adrienne A; Arnold, Mark E

    2011-12-01

    Unstable drug candidates often lead to complexity for both sample collection and bioanalysis. Dried blood spot (DBS) technology is believed to be a viable solution to address this problem. However, it is currently a challenge to evaluate compound stability on DBS due to its solid format. The observed compound loss on a DBS card could be degradation and/or incomplete recovery. Therefore, a reliable bioanalytical method which can differentiate recovery loss from degradation is necessary for such stability evaluation. In this paper, the stability of an unstable drug candidate (KAI-9803) in human blood was evaluated using DBS. A reliable approach to evaluating analyte stability on DBS was developed with an appropriate time-zero sample, a consistent DBS sample processing method, and a suitable positive control. Commercially available DBS cards were evaluated, and it was found that KAI-9803 degraded during the drying process. An in-house modified DBS card was developed and demonstrated to be able to stabilize KAI-9803 during the drying process by rapidly lowering the pH of the spotted blood sample. The storage stability of KAI-9803 in human blood on this new card has been established for at least 48 days at room temperature. This in-house modified DBS card could provide a generic approach for other compounds which require stabilization at a low pH. PMID:21995953

  7. Low voltage to high voltage level shifter and related methods

    NASA Technical Reports Server (NTRS)

    Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

    2006-01-01

    A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

  8. Evaluation of the physical properties, bulk density and aggregate stability of potential substrates in quarry restoration.

    NASA Astrophysics Data System (ADS)

    Jordan, M.; Garcia-Orenes, F.; Mataix-Solera, J.; Garcia-Sanchez, E.

    2012-04-01

    Quarrying activity entails significant environmental impact affecting the soil, water, plants, landscape, etc. One of the most important impacts is the loss of the productive layer of the soil and its vegetation cover. However, mining activities are absolutely necessary for human development; keeping them sustainable implicates looking for viable solutions for the restoration of these areas to prevent degradation during and after the exploitation period. The aim of this study was to evaluate different substrates obtained from different mixes of sewage sludge and different mine spoils, to check how they are effective in quarry restoration, and to establish good practises in mining restoration. Also, the study tried to approach two refuses, one deriving from mining activity, as are the mine spoils that need to be reused for their valorisation, and the other, sewage sludge, obtained in the water depuration process to acquire a cheap substrate for soil rehabilitation. This preliminary work, which is included in a larger study, shows the results obtained from two physical properties studied, bulk density and aggregate stability, as key properties in the substrate structure for use in mining area restoration. Two doses of composted sewage sludge (30 and 90 Tm/Ha), both very rich in calcium carbonate, were applied to two different mine spoils under lab conditions. The first material, of poor quality, originated from the acquisition of arid particles in crushed limestone (Z). It is characterized by stable ''coarse elements'' predominance (up to 75% of its weight), and by the presence of elevated percentages of sand. The other waste material tested comes from limestone extraction (basically formed by the levels of interspersed non-limestone materials and the remains of stripped soils (D)). The results show that the high dose of sewage sludge applied to a mix of the two mine spoils significantly increased the percentage of stable aggregates by more than 50% than the control (the same mix without sewage sludge) and also produced an important decrease in the bulk density with respect to the control. This substrate could be a good material for use in quarry restoration.

  9. Fault Current Limiter by Series Connected Voltage Source Inverter

    NASA Astrophysics Data System (ADS)

    Hojo, Masahide; Kuroe, Norihito; Ohnishi, Tokuo

    In recent years, various types of fault current limiter (FCL) have been developed, because installation of the FCL will bring a lot of benefits to power system operation. Power system controllers based on a concept of Flexible AC Transmission Systems (FACTS) can also be applicable as the FCL with growing power ratings of them. Such FCLs are expected to contribute power system stabilization or power quality enhancement in addition to fault current limitation. Authors have developed a new type of FCL, which consists of a series reactor and a self-commutated voltage source inverter connected in series with a power distribution line by a coupling transformer. In case of a system fault, the FCL will insert a sufficiently large inductance in series with the distribution line by both the series reactor and the inverter, then it will reduce the fault current. On the other hand, the inverter compensates a voltage drop across the series reactor in a standby mode. As a result, the FCL behaves like a negligible impedance in the standby mode. One of the distinctive features of the FCL is a simple configuration because its control strategy does not require an active power source. In addition, inverter voltage rating of the proposed FCL can be reduced by installing the series reactor as compared with other converter-based FCLs. The aim of this paper is to evaluate the operating characteristics of the FCL with both simulation and experimental studies.

  10. Evaluation of miniature vacuum ultraviolet lamps for stability and operating characteristics, Lyman-Alpha task

    NASA Technical Reports Server (NTRS)

    Hurd, W. A.

    1985-01-01

    Modifications required to change the near ultraviolet source in the Optical Contamination Monitor to a source with output at or near the Lyman-Alpha hydrogen line are discussed. The effort consisted of selecting, acquiring and testing candidate miniature ultraviolet lamps with significant output in or near 121.6 nm. The effort also included selection of a miniature dc high-voltage power supply capable of operating the lamp. The power supply was required to operate from available primary power supplied by the Optical Effect Module (DEM) and it should be flight qualified or have the ability to be qualified by the user.

  11. Stability of smooth and rough mini-implants: clinical and biomechanical evaluation - an in vivostudy

    PubMed Central

    Vilani, Giselle Naback Lemes; Ruellas, Antnio Carlos de Oliveira; Elias, Carlos Nelson; Mattos, Cludia Trindade

    2015-01-01

    Objective: To compare in vivo orthodontic mini-implants (MI) of smooth (machined) and rough (acid etched) surfaces, assessing primary and secondary stability. Methods: Thirty-six (36) MI were inserted in the mandibles of six (6) dogs. Each animal received six (6) MI. In the right hemiarch, three (3) MI without surface treatment (smooth) were inserted, whereas in the left hemiarch, another three (3) MI with acid etched surfaces (rough) were inserted. The two distal MI in each hemiarch received an immediate load of 1.0 N for 16 weeks, whereas the MI in the mesial extremity was not subject to loading. Stability was measured by insertion and removal torque, initial and final mobility and by inter mini-implant distance. Results: There was no statistical behavioral difference between smooth and rough MI. High insertion torque and reduced initial mobility were observed in all groups, as well as a reduction in removal torques in comparison with insertion torque. Rough MI presented higher removal torque and lower final mobility in comparison to smooth MI. MI did not remain static, with displacement of rough MI being smaller in comparison with smooth MI, but with no statistical difference. Conclusions: MI primary stability was greater than stability measured at removal. There was no difference in stability between smooth and rough MI when assessing mobility, displacement and insertion as well as removal torques. PMID:26560819

  12. Laboratory evaluation of the pointing stability of the ASPS Vernier System

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The annular suspension and pointing system (ASPS) is an end-mount experiment pointing system designed for use in the space shuttle. The results of the ASPS Vernier System (AVS) pointing stability tests conducted in a laboratory environment are documented. A simulated zero-G suspension was used to support the test payload in the laboratory. The AVS and the suspension were modelled and incorporated into a simulation of the laboratory test. Error sources were identified and pointing stability sensitivities were determined via simulation. Statistical predictions of laboratory test performance were derived and compared to actual laboratory test results. The predicted mean pointing stability during simulated shuttle disturbances was 1.22 arc seconds; the actual mean laboratory test pointing stability was 1.36 arc seconds. The successful prediction of laboratory test results provides increased confidence in the analytical understanding of the AVS magnetic bearing technology and allows confident prediction of in-flight performance. Computer simulations of ASPS, operating in the shuttle disturbance environment, predict in-flight pointing stability errors less than 0.01 arc seconds.

  13. Array-level stability enhancement of 50 nm AlxOy ReRAM

    NASA Astrophysics Data System (ADS)

    Iwasaki, Tomoko Ogura; Ning, Sheyang; Yamazawa, Hiroki; Takeuchi, Ken

    2015-12-01

    ReRAM's low voltage and low current programmability are attractive features to solve the scaling issues of conventional floating gate Flash. However, read instability in ReRAM is a critical issue, due to random telegraph noise (RTN), sensitivity to disturb and retention. In this work, the array-level characteristics of read stability in 50 nm AlxOy ReRAM are investigated and a circuit technique to improve stability is proposed and evaluated. First, in order to quantitatively assess memory cell stability, a method of stability characterization is defined. Next, based on this methodology, a proposal to improve read stability, called "stability check loop" is evaluated. The stability check loop is a stability verification procedure, by which, instability improvement of 7×, and read error rate improvement of 40% are obtained.

  14. High voltage power supply

    NASA Technical Reports Server (NTRS)

    Ruitberg, A. P.; Young, K. M. (inventors)

    1985-01-01

    A high voltage power supply is formed by three discrete circuits energized by a battery to provide a plurality of concurrent output signals floating at a high output voltage on the order of several tens of kilovolts. In the first two circuits, the regulator stages are pulse width modulated and include adjustable ressistances for varying the duty cycles of pulse trains provided to corresponding oscillator stages while the third regulator stage includes an adjustable resistance for varying the amplitude of a steady signal provided to a third oscillator stage. In the first circuit, the oscillator, formed by a constant current drive network and a tuned resonant network included a step up transformer, is coupled to a second step up transformer which, in turn, supplies an amplified sinusoidal signal to a parallel pair of complementary poled rectifying, voltage multiplier stages to generate the high output voltage.

  15. High-voltage distributors

    NASA Technical Reports Server (NTRS)

    Mcchesney, J. F., Jr.

    1974-01-01

    Two distributors reduce high-voltage breakdowns and corona discharges. Both distributors are constructed to prevent air traps and facilitate servicing without soldering. Occurrence of coronas is also minimized due to smooth surfaces of device.

  16. Imaging voltage in neurons

    PubMed Central

    Peterka, Darcy S.; Takahashi, Hiroto; Yuste, Rafael

    2011-01-01

    In the last decades, imaging membrane potential has become a fruitful approach to study neural circuits, especially in invertebrate preparations with large, resilient neurons. At the same time, particularly in mammalian preparations, voltage imaging methods suffer from poor signal to noise and secondary side effects, and they fall short of providing single-cell resolution when imaging of the activity of neuronal populations. As an introduction to these techniques, we briefly review different voltage imaging methods (including organic fluorophores, SHG chromophores, genetic indicators, hybrid, nanoparticles and intrinsic approaches), and illustrate some of their applications to neuronal biophysics and mammalian circuit analysis. We discuss their mechanisms of voltage sensitivity, from reorientation, electrochromic or electro-optical phenomena, to interaction among chromophores or membrane scattering, and highlight their advantages and shortcomings, commenting on the outlook for development of novel voltage imaging methods. PMID:21220095

  17. Use of analytical electron microscopy in evaluating ferrite stability in austenitic stainless steel welds

    SciTech Connect

    Vitek, J.M.; David, S.A.

    1986-01-01

    Stainless steel weld filler metals are prone to hot-cracking during welding. If the primary mode of solidification is ferrite formation rather than austenite formation, the tendency for hot-cracking is reduced. Type 308 stainless steel is such a filler metal which solidifies as primary ferrite and is relatively immune to hot-cracking problems. During further cooling, the primary ferrite transforms to austenite. When such duplex austenite plus ferrite weld microstructures are subjected to elevated temperature applications, the residual ferrite is unstable and transforms. Analytical electron microscopy has been used to study the ferrite stability. Results have provided insight into the stability of ferrite during welding and also during service at elevated temperatures. This paper considers three cases in which the use of analytical electron microscopy has led to understanding of ferrite stability in duplex type 308 stainless steel welds.

  18. Quantitative evaluation of transient heat transfer on axial flow compressor stability

    NASA Astrophysics Data System (ADS)

    Crawford, R. A.; Burwell, A. E.

    1985-07-01

    An essential factor for acceptable engine performance and safety in the case of an aircraft gas turbine engine is the stable operation of the compression system. A number of basic research programs were conducted to investigate the influence of transient heat transfer effects on axial flow compressor stability. The results of these programs led to the conclusion that sound theoretical models predict a significant influence of transient heat transfer on compressor stability. However, no transient turbine engine data were available to validate model predictions. The present investigation utilizes high quality transient turbine engine data to quantify and support the reported conclusion. Attention is given to core compressor thermal energy storage, standard stability tests for gas turbine engines, transient mass flow calculations, transient heat transfer calculations, blade heat transfer flux, heat transfer results, and a comparison.

  19. Electrical safety for high voltage arrays

    NASA Technical Reports Server (NTRS)

    Marshall, N. A.

    1983-01-01

    A number of key electrical safety requirements for the high voltage arrays of central station photovoltaic power systems are explored. The suitability of representative industrial DC power switchgear for control and fault protection was evaluated. Included were AC/DC circuit breakers, electromechanical contactors and relays, load interruptors, cold disconnect devices, sectionalizing switches, and high voltage DC fuses. As appropriate, steady state and transient characteristics were analyzed. Failure modes impacting upon operation and maintenance safety were also identified, as were the voltage withstand and current interruption levels.

  20. Analysis of NSTX TF Joint Voltage Measurements

    SciTech Connect

    R, Woolley

    2005-10-07

    This report presents findings of analyses of recorded current and voltage data associated with 72 electrical joints operating at high current and high mechanical stress. The analysis goal was to characterize the mechanical behavior of each joint and thus evaluate its mechanical supports. The joints are part of the toroidal field (TF) magnet system of the National Spherical Torus Experiment (NSTX) pulsed plasma device operating at the Princeton Plasma Physics Laboratory (PPPL). Since there is not sufficient space near the joints for much traditional mechanical instrumentation, small voltage probes were installed on each joint and their voltage monitoring waveforms have been recorded on sampling digitizers during each NSTX ''shot''.

  1. Low-voltage gyrotrons

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

    2013-03-01

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

  2. High voltage DC power supply

    DOEpatents

    Droege, Thomas F.

    1989-01-01

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively.

  3. High voltage DC power supply

    DOEpatents

    Droege, T.F.

    1989-12-19

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively. 7 figs.

  4. STABILIZATION OF MERCURY IN WASTE MATERIAL FROM THE SULFUR BANK MERCURY MINE, INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    Three innovative technologies for stabilization of mercury were demonstrated in a treatability study performed on two waste rock materials from the Sulfur Bank Mercury Mine, a Superfund site in northern California. The treatability study was jointly sponsored by two EPA programs:...

  5. AN EVALUATION OF FACTORS AFFECTING THE SOLIDIFICATION/STABILIZATION OF HEAVY METAL SLUDGE

    EPA Science Inventory

    Solidification/stabilization (SIS) of hazardous waste involves mixing the waste with a binder material to enhance the physical properties of the waste and to immobilize contaminants that may be detrimental to the environment. Many hazardous wastes contain materials that are know...

  6. Safety evaluation for the interim stabilization of Tank 241-C-103

    SciTech Connect

    Geschke, G.R.

    1995-03-01

    This document provides the basis for interim stabilization of tank 241-C-103. The document covers the removal of the organic liquid layer and the aqueous supernatant from tank 241-C-103. Hazards are identified, consequences are calculated and controls to mitigate or prevent potential accidents are developed.

  7. The Evaluation of the Reliability of Periotest for Implant Stability Measurements: An In Vitro Study.

    PubMed

    Bilhan, Hakan; Cilingir, Altug; Bural, Canan; Bilmenoglu, Caglar; Sakar, Olcay; Geckili, Onur

    2015-08-01

    Periotest (Medizintechnik Gulden, Modautal, Germany) is a widely accepted implant stability measurement method, although the reliability is not well known. The aim of this in vitro study was to investigate the reliability of the Periotest in implant stability measurements. Thirty implants were placed in 3 cow ribs. The stability of each implant was measured by insertion torque, resonance frequency analyses, and Periotest and then compared. The Periotest values (PTVs) were measured by 4 different examiners. The measurements were repeated twice in both the buccal and mesial directions, for each implant at 2-hour intervals and the intra- and interobserver reliability of Periotest was measured. Results showed that the intraobserver reliability of the Periotest was excellent for the buccal PTVs but fair to poor for the mesial PTVs. The interobserver reliability of the Periotest was excellent for the buccal PTVs but poor for the mesial PTVs. No significance was found between the PTVs and IT values (P = .803) and PTVs and ISQ values, whereas a 47.1% significant correlation was detected between the IT values and ISQ values (P = .009). The present study indicates that only Periotest measurements from buccal result in excellent intra- and interobserver reliability for the quantification of the implant stability. PMID:24593232

  8. STABILITY EVALUATION OF SULFUR DIOXIDE, NITRIC OXIDE AND CARBON MONOXIDE GASES IN CYLINDERS

    EPA Science Inventory

    The US EPA recommends in their EPA Traceability Protocol 1 and 2 that reactive gases be reanalyzed every six months. The purpose of this study was to assess the stability of selected reactive gases as a function of time to determine the feasibility of extending the recertificatio...

  9. An Outcome Evaluation of an Inpatient Crisis Stabilization and Assessment Program for Youth

    ERIC Educational Resources Information Center

    Greenham, Stephanie L.; Bisnaire, Lise

    2008-01-01

    Objective: To describe characteristics and outcomes of youth aged 7 to 17 who received inpatient psychiatric and mental health services along different clinical pathways of a new service delivery model. Method: Participants included 211 admissions to an inpatient crisis stabilization and assessment program over a one-year period. Standardized

  10. Influence of input parameters on dynamic orbital stability of walking: in-silico and experimental evaluation.

    PubMed

    Riva, Federico; Bisi, Maria Cristina; Stagni, Rita

    2013-01-01

    Many measures aiming to assess the stability of human motion have been proposed in the literature, but still there is no commonly accepted way to define or quantify locomotor stability. Among these measures, orbital stability analysis via Floquet multipliers is still under debate. Some of the controversies concerning the use of this technique could lie in the absence of a standard implementation. The aim of this study was to analyse the influence of i) experimental measurement noise, ii) variables selected for the construction of the state space, and iii) number of analysed cycles on the outputs of orbital stability applied to walking. The analysis was performed on a 2-dimensional 5-link walking model and on a sample of 10 subjects performing long over-ground walks. Noise resulting from stereophotogrammetric and accelerometric measurement systems was simulated in the in-silico analysis. Maximum Floquet multipliers resulted to be affected by both number of analysed strides and state space composition. The effect of experimental noise was found to be slightly more potentially critical when analysing stereophotogrammetric data then when dealing with acceleration data. Experimental and model results were comparable in terms of overall trend, but a difference was found in the influence of the number of analysed cycles. PMID:24260498

  11. Spatial analyses to evaluate multi-crop yield stability for a field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper proposes that yield stability patterns exist for multiple crops planted on the same land area over a period of years that growers can use to their advantage in planning crop management strategies using precision agriculture technologies. This initial study examines the relationship of s...

  12. Influence of Input Parameters on Dynamic Orbital Stability of Walking: In-Silico and Experimental Evaluation

    PubMed Central

    Riva, Federico; Bisi, Maria Cristina; Stagni, Rita

    2013-01-01

    Many measures aiming to assess the stability of human motion have been proposed in the literature, but still there is no commonly accepted way to define or quantify locomotor stability. Among these measures, orbital stability analysis via Floquet multipliers is still under debate. Some of the controversies concerning the use of this technique could lie in the absence of a standard implementation. The aim of this study was to analyse the influence of i) experimental measurement noise, ii) variables selected for the construction of the state space, and iii) number of analysed cycles on the outputs of orbital stability applied to walking. The analysis was performed on a 2-dimensional 5-link walking model and on a sample of 10 subjects performing long over-ground walks. Noise resulting from stereophotogrammetric and accelerometric measurement systems was simulated in the in-silico analysis. Maximum Floquet multipliers resulted to be affected by both number of analysed strides and state space composition. The effect of experimental noise was found to be slightly more potentially critical when analysing stereophotogrammetric data then when dealing with acceleration data. Experimental and model results were comparable in terms of overall trend, but a difference was found in the influence of the number of analysed cycles. PMID:24260498

  13. Superfund Innovative Technology Evaluation - Demonstration Bulletin: In-Situ Soil Stabilization

    EPA Science Inventory

    In-situ stabilization technology immobilizes organics and inorganic compounds in wet or dry soils by using reagents (additives) to polymerize with the soils and sludges producing a cement-like mass. Two basic components of this technology are the Geo-Con/DSM Deep Soil Mixing Sy...

  14. Improved Comparative Signature Diagrams to Evaluate Similarity of Storage Stability Profiles of Different IgG1 mAbs.

    PubMed

    Kim, Jae Hyun; Joshi, Sangeeta B; Esfandiary, Reza; Iyer, Vidyashankara; Bishop, Steven M; Volkin, David B; Middaugh, Charles Russell

    2016-03-01

    For therapeutic protein analytical studies related to evaluating lot-to-lot variability, different processes and/or formulations, or biosimilars, there is growing interest in applying novel data visualization tools for fingerprint analysis to identify statistically significant differences between 2 samples. Comparative Signature Diagrams (CSDs) were previously developed to display such differences as colored contour plots using a variety of biophysical data sets. In this study, several improvements are proposed to enhance readability and quantitative determinations of CSDs using protein stability data from more commonly used analytical methods such as size exclusion chromatography and capillary isoelectric focusing. To demonstrate the effectiveness of improved CSDs for data visualization, an accelerated and real-time stability study was set up for an IgG1 mAb (mAb A) and its corresponding triple mutant (mAb E). The stability profiles of both mAbs were compared for differences in aggregation (size exclusion chromatography) and charge heterogeneity (capillary isoelectric focusing) profiles over time. Both traditional data analysis and the improved CSDs conclude that the triple mutant mAb E is more susceptible to physicochemical degradation than mAb A under accelerated conditions. The current abilities and limitations of CSDs to provide fingerprint analysis of protein stability profiles to facilitate the determination of similarity versus nonsimilarity between samples is discussed. PMID:26886311

  15. High voltage pulse generator

    DOEpatents

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  16. Off-set stabilizer for comparator output

    DOEpatents

    Lunsford, James S. (Los Alamos, NM)

    1991-01-01

    A stabilized off-set voltage is input as the reference voltage to a comparator. In application to a time-interval meter, the comparator output generates a timing interval which is independent of drift in the initial voltage across the timing capacitor. A precision resistor and operational amplifier charge a capacitor to a voltage which is precisely offset from the initial voltage. The capacitance of the reference capacitor is selected so that substantially no voltage drop is obtained in the reference voltage applied to the comparator during the interval to be measured.

  17. Device for monitoring cell voltage

    DOEpatents

    Doepke, Matthias; Eisermann, Henning

    2012-08-21

    A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

  18. Evaluation of thermal-oxidative stability and antiglioma activity of Zanthoxylum tingoassuiba essential oil entrapped into multi- and unilamellar liposomes.

    PubMed

    Detoni, Cassia B; de Oliveira, Diêgo Madureira; Santo, Islane E; Pedro, André São; El-Bacha, Ramon; da Silva Velozo, Eudes; Ferreira, Domingos; Sarmento, Bruno; de Magalhães Cabral-Albuquerque, Elaine C

    2012-03-01

    Zanthoxylum tinguassuiba essential oil (ZtEO) contains α-bisabolol, a known antiglioma sesquiterpene, among other potentially active substances. Medical applications of this essential oil require advances in the design of distinctive carriers due to its low water solubility and easy degradation by heat, light, and oxygen. The aim of this work was to evaluate enhancement in oxidative stability and the ability to reduce glioblastoma cell viability of ZtEO loaded into liposomes. Multi- and unilamellar vesicles were prepared to carry ZtEO. By using thermal analysis, it was observed that thermal-oxidative stability of the liposomal ZtEO was enhanced, when compared to its free form. Liposomal ZtEO also presented significant apoptotic-inducing activity for glioma cells. These results show that liposomal systems carrying ZtEO may be a potential alternative for gliobastoma treatment. PMID:21548711

  19. Evaluation of the correlation between insertion torque and primary stability of dental implants using a block bone test

    PubMed Central

    Bayarchimeg, Dorjpalam; Namgoong, Hee; Kim, Byung Kook; Kim, Myung Duk; Kim, Sungtae; Kim, Tae-Il; Seol, Yang Jo; Lee, Yong Moo; Ku, Young; Rhyu, In-Chul; Lee, Eun Hee

    2013-01-01

    Purpose Implant stability at the time of surgery is crucial for the long-term success of dental implants. Primary stability is considered of paramount importance to achieve osseointegration. The purpose of the present study was to investigate the correlation between the insertion torque and primary stability of dental implants using artificial bone blocks with different bone densities and compositions to mimic different circumstances that are encountered in routine daily clinical settings. Methods In order to validate the objectives, various sized holes were made in bone blocks with different bone densities (#10, #20, #30, #40, and #50) using a surgical drill and insertion torque together with implant stability quotient (ISQ) values that were measured using the Osstell Mentor. The experimental groups under evaluation were subdivided into 5 subgroups according to the circumstances. Results In group 1, the mean insertion torque and ISQ values increased as the density of the bone blocks increased. For group 2, the mean insertion torque values decreased as the final drill size expanded, but this was not the case for the ISQ values. The mean insertion torque values in group 3 increased with the thickness of the cortical bone, and the same was true for the ISQ values. For group 4, the mean insertion torque values increased as the cancellous bone density increased, but the correlation with the ISQ values was weak. Finally, in group 5, the mean insertion torque decreased as the final drill size increased, but the correlation with the ISQ value was weak. Conclusions Within the limitations of the study, it was concluded that primary stability does not simply depend on the insertion torque, but also on the bone quality. PMID:23508040

  20. Novel perchlorate and phosphate salts of vinpocetine: Characterization, relative solid-state stability evaluation and Hirshfeld surface analysis

    NASA Astrophysics Data System (ADS)

    Ma, Yu-heng; Ge, Shu-wang; Wang, Wei; Zheng, Qiang; Zuo, Yun-wei; Zhong, Chang-jiang; Sun, Bai-wang

    2016-02-01

    Salt formation is a very common and effective method of improving a drug's physicochemical properties such as hygroscopicity and physical stability at different humidity conditions. Aqueous solubility is another important parameter that can be improved by salt formation; however this strategy has not yet been evaluated for the important alkaloid drug, Vinpocetine. A poorly water-soluble basic drug (water solubility value≈ 5 μg/ml and pKa value of 7.31), vinpocetine was converted into two novel salts in this work, with perchloric acid and phosphoric acid in a 1: 1 M ratio. However, an unexpected phase transformation occurred in one of the salts after the stability test, which is a major concern in studies on dosage form. The conversion of the salt to free base could be related to the temperature-humidity profile of the type II salt (formed by vinpocetine and phosphoric acid). When the temperature was more than 70 °C under high humidity conditions of more than 80%, the phase transformation occurred immediately. To gain further understanding of this phenomenon, single crystals of the two novel salts were prepared and characterized by single crystal X-ray diffraction, Powder-XRD, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Constituents of the crystalline phase were also investigated in terms of Hirshfeld surface. The structures were found to be stabilized by H⋯H, C-H⋯O, O-H⋯N and C-H⋯π intermolecular interactions. Our stability studies showed that both these two novel salts could improve the stability of vinpocetine, however the type I salt (formed by vinpocetine and perchloric acid) offers more advantages. This finding will provide valuable information for vinpocetine dosage form development.

  1. Optical S-ALOHA/CDMA Systems for Multirate Applications: Architecture, Performance Evaluation, and System Stability

    NASA Astrophysics Data System (ADS)

    Raad, Robert; Inaty, Elie; Fortier, Paul; Shalaby, Hossam M. H.

    2006-05-01

    In this paper, a new multirate optical network based on a hybrid slotted-ALOHA (S-ALOHA)/overlapped code division multiple access (O-CDMA) system is proposed as an effective way of integrating multiclass traffic. The key issue in this proposal is to exploit the potential of the optical O-CDMA using fiber Bragg gratings when jointly used with the S-ALOHA protocol in a link layer. The newly proposed system is modeled using a general Markov chain from which both the system throughput and the average packet delay are derived. The system stability passing through a general finite user model is also envisaged. The system is then compared to the classical S-ALOHA/variable processing gain (VPG) CDMA system. Numerical results show that the proposed system outperforms the latter one, especially at high transmission rates. In addition, stability measures demonstrate that the overlapped system tends to be more stable than the VPG system.

  2. Correlation and evaluation of inplane stability characteristics for an advanced bearingless main rotor

    NASA Technical Reports Server (NTRS)

    Weller, W. H.

    1983-01-01

    A program of experimental and analytical research was performed to demonstrate the degree of correlation achieved between measured and computed rotor inplane stability characteristics. The experimental data were obtained from hover and wind tunnel tests of a scaled bearingless main rotor model. Both isolated rotor and free-hub conditions were tested. Test parameters included blade built-in cone and sweep angles; rotor inplane structural stiffness and damping; pitch link stiffness and location; and fuselage damping, inertia, and natural frequency. Analytical results for many test conditions were obtained. In addition, the analytical and experimental results were examined to ascertain the effects of the test parameters on rotor ground and air resonance stability. The results from this program are presented herein in tabular and graphical form.

  3. In-Well Sediment Incubators to Evaluate Microbial Community Stability and Dynamics following Bioimmobilization of Uranium

    SciTech Connect

    Baldwin, Brett R.; Peacock, Aaron D.; Gan, M.; Resch, Charles T.; Arntzen, Evan V.; Smithgall, A. N.; Pfiffner, S.; Freifeld, Barry M.; White, D. C.; Long, Philip E.

    2009-09-23

    An in-situ incubation device (ISI) was developed in order to investigate the stability and dynamics of sediment associated microbial communities to prevailing subsurface oxidizing or reducing conditions. Here we describe the use of these devices at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site. During the 7 month deployment oxidized Rifle aquifer background sediments (RABS) were deployed in previously biostimulated wells under iron reducing conditions, cell densities of known iron reducing bacteria including Geobacteraceae increased significantly showing the microbial community response to local subsurface conditions. PLFA profiles of RABS following in situ deployment were strikingly similar to those of adjacent sediment cores suggesting ISI results could be extrapolated to the native material of the test plots. Results for ISI deployed reduced sediments showed only slight changes in community composition and pointed toward the ability of the ISIs to monitor microbial community stability and response to subsurface conditions.

  4. Preparation of iron bound succinylated milk protein concentrate and evaluation of its stability.

    PubMed

    Shilpashree, B G; Arora, Sumit; Sharma, Vivek; Bajaj, Rajesh Kumar; Tomar, S K

    2016-04-01

    Major problems associated with the fortification of soluble iron salts include chemical reactivity and incompatibility with other components. Milk protein concentrate (MPC) are able to bind significant amount of iron due to the presence of both casein and whey protein. MPC in its native state possess very poor solubility, therefore, succinylated derivatives of MPC (succ. MPC) were also used for the preparation of protein-iron complex. Preparation of the complex involved centrifugation (to remove insoluble iron), ultrafiltration (to remove unbound iron) and lyophilisation (to attain in dry form). Iron binding ability of MPC enhanced significantly (P<0.05) upon succinylation. Stability of bound iron from both varieties of complexes was monitored under different conditions encountered during processing. Higher stability (P<0.05) of bound iron was observed in succ. MPC-iron complex than native protein complex. This method could be adopted for the production of stable iron enriched protein, an organic iron source. PMID:26593557

  5. Impaction grafted bone chip size effect on initial stability in an acetabular model: Mechanical evaluation

    PubMed Central

    Holton, Colin; Bobak, Peter; Wilcox, Ruth; Jin, Zhongmin

    2013-01-01

    Introduction Acetabular bone defect reconstruction is an increasing problem for surgeons with patients undergoing complex primary or revision total hip replacement surgery. Impaction bone grafting is one technique that has favourable long-term clinical outcome results for patients who undergo this reconstruction method for acetabular bone defects. Creating initial mechanical stability of the impaction bone graft in this technique is known to be the key factor in achieving a favourable implant survival rate. Different sizes of bone chips were used in this technique to investigate if the size of bone chips used affected initial mechanical stability of a reconstructed acetabulum. Methodology Twenty acetabular models were created in total. Five control models were created with a cemented cup in a normal acetabulum. Then five models in three different groups of bone chip size were constructed. The three groups had an acetabular protrusion defect reconstructed using either; 24mm3, 10mm3 or 20mm3 bone chip size for impaction grafting reconstruction. The models underwent compression loading up to 9500N and displacement within the acetabular model was measured indicating the initial mechanical stability. Results This study reveals that, although not statistically significant, the largest (20mm3) bone chip size grafted models have an inferior maximum stiffness compared to the medium (10mm3) bone chip size. Interpretations Our study suggests that 10mm3 size of bone chips provide better initial mechanical stability compared to smaller or larger bone chips. We dismissed the previously held opinion that the biggest practically possible graft is best for acetabular bone graft impaction. PMID:24396238

  6. Evaluating Arctic Lower Tropospheric Stability in CAM4 and CAM5

    NASA Astrophysics Data System (ADS)

    Barton, N. P.; Klein, S. A.; Boyle, J. S.

    2012-12-01

    Previous research has shown that the CMIP3 models have an Arctic lower troposphere that is more stable than reanalysis products, and that this bias may lead to an unrealistic Arctic feedback. Basic questions of why these models drift toward a more stable lower troposphere in the Arctic have not been thoroughly investigated. What season is the bias more likely? What atmospheric level or levels is causing the bias? In this analysis, we examine the lower tropospheric stability in CAM4 and CAM5. The models run in forecast and AMIP mode. The lower tropospheric stability is examined across the Arctic domain with analysis products, and in more detail using in-situ data at the North Slope of Alaska. We show that CAM4's and CAM5's Arctic lower tropospheric stability bias is greater during the winter months, and that the bias is largely due to models' surface temperature drifting lower than observations. Reasons why the models' surface temperatures are lower are investigated. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.iases in lower-tropospheric stability (top), potential temperature at 700 hPa (middle), and potential temperature (bottom) at the lowest model level (LML) for CAM4 (left) and CAM5 (right). The biases are averaged poleward of 60N and are measured with respect to ECMWF analysis. The x-axis indicates month and the y-axis indicates the hindcast day in which models were analyzed with the top row illustrating the bias in AMIP mode

  7. An eco-spatial index for evaluating stabilization state of sand dunes

    NASA Astrophysics Data System (ADS)

    Rubinstein, Yehonathan; Groner, Elli; Yizhaq, Hezi; Svoray, Tal; Bar (Kutiel), Pua

    2013-06-01

    Geomorphologies tend to categorize dunes into three major states (mobile, semi-stabilized and stabilized) based on their shape and mobility rate. However, the ecologists try to find bio-indicators that can characterize the mobility rate and the ecological features of the various dune states. Unfortunately, there are limited numbers of significant bio-indicators, if any. The aim of our study was to develop a Dune Assemblage Index (DAI) in order to indicate the affinity of annual plants and arthropods assemblages to dune mobility. The DAI values range between 0 for stabilized dunes and 1 for bare and active dunes. The index was calculated for 10 coastal dunes in Nizzanim nature reserve, located at the southern part of the Israeli Mediterranean coast, from data that were collected in the years 2006 and 2007. Generally, the lower the vegetation cover is, the higher are DAI values for both taxon groups. Generalist species tend to mask the differences between active and stabilized dunes whereas psammophiles (sand-dwelling species) tend to increase the DAI values. Additionally, the DAI may differ among dunes with the same perennial coverage due to differences in the spatial plant distribution patterns. Likewise, the DAI depends also on the distance of the dunes from rural areas, which encourage invasion of generalist species, thus decreases the DAI value. This new defined spatial index that relies on plant and animal assemblages, rather than on individual bio-indicators, can be adapted to any taxon and dune ecosystems. The use of several taxons may support better understanding of the ecosystem state of the dune.

  8. Evaluation of metabolically stabilized angiotensin IV analogs as procognitive/antidementia agents.

    PubMed

    McCoy, Alene T; Benoist, Caroline C; Wright, John W; Kawas, Leen H; Bule-Ghogare, Jyote M; Zhu, Mingyan; Appleyard, Suzanne M; Wayman, Gary A; Harding, Joseph W

    2013-01-01

    Angiotensin IV (AngIV: VYIHPF)-related peptides have long been recognized as procognitive agents with potential as antidementia therapeutics. Their development as useful therapeutics, however, has been limited by physiochemical properties that make them susceptible to metabolic degradation and impermeable to gut and blood-brain barriers. A previous study demonstrated that the core structural information required to impart the procognitive activity of the AngIV analog, norleucine(1)-angiotensin IV, resides in its three N-terminal amino acids, Nle-Tyr-Ile. The goal of this project was to chemically modify this tripeptide in such a way to enhance its metabolic stability and barrier permeability to produce a drug candidate with potential clinical utility. Initial results demonstrated that several N- and C-terminal modifications lead to dramatically improved stability while maintaining the capability to reverse scopolamine-induced deficits in Morris water maze performance and augment hippocampal synaptogenesis. Subsequent chemical modifications, which were designed to increase hydrophobicity and decrease hydrogen bonding, yielded an orally active, blood-barrier permeant, metabolically stabilized analog, N-hexanoic-Tyr-Ile-(6) aminohexanoic amide (dihexa), that exhibits excellent antidementia activity in the scopolamine and aged rat models and marked synaptogenic activity. These data suggest that dihexa may have therapeutic potential as a treatment of disorders, such as Alzheimer's disease, where augmented synaptic connectivity may be beneficial. PMID:23055539

  9. Evaluation of Metabolically Stabilized Angiotensin IV Analogs as Procognitive/Antidementia Agents

    PubMed Central

    McCoy, Alene T.; Benoist, Caroline C.; Wright, John W.; Kawas, Leen H.; Bule-Ghogare, Jyote M.; Zhu, Mingyan; Appleyard, Suzanne M.; Wayman, Gary A.

    2013-01-01

    Angiotensin IV (AngIV: VYIHPF)–related peptides have long been recognized as procognitive agents with potential as antidementia therapeutics. Their development as useful therapeutics, however, has been limited by physiochemical properties that make them susceptible to metabolic degradation and impermeable to gut and blood-brain barriers. A previous study demonstrated that the core structural information required to impart the procognitive activity of the AngIV analog, norleucine1-angiotensin IV, resides in its three N-terminal amino acids, Nle-Tyr-Ile. The goal of this project was to chemically modify this tripeptide in such a way to enhance its metabolic stability and barrier permeability to produce a drug candidate with potential clinical utility. Initial results demonstrated that several N- and C-terminal modifications lead to dramatically improved stability while maintaining the capability to reverse scopolamine-induced deficits in Morris water maze performance and augment hippocampal synaptogenesis. Subsequent chemical modifications, which were designed to increase hydrophobicity and decrease hydrogen bonding, yielded an orally active, blood-barrier permeant, metabolically stabilized analog, N-hexanoic-Tyr-Ile-(6) aminohexanoic amide (dihexa), that exhibits excellent antidementia activity in the scopolamine and aged rat models and marked synaptogenic activity. These data suggest that dihexa may have therapeutic potential as a treatment of disorders, such as Alzheimer’s disease, where augmented synaptic connectivity may be beneficial. PMID:23055539

  10. Iron hydroxy carbonate formation in zerovalent iron permeable reactive barriers: Characterization and evaluation of phase stability

    SciTech Connect

    Wilkin, Richard T.; Lee, T.R.

    2010-10-22

    Predicting the long-term potential of permeable reactive barriers for treating contaminated groundwater relies on understanding the endpoints of biogeochemical reactions between influent groundwater and the reactive medium. Iron hydroxy carbonate (chukanovite) is frequently observed as a secondary mineral precipitate in granular iron PRBs. Mineralogical characterization was carried out using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and X-ray absorption spectroscopy on materials collected from three field-based PRBs in the US (East Helena, MT; Elizabeth City, NC; Denver Federal Center, CO). These PRBs were installed to treat a range of contaminants, including chlorinated organics, hexavalent chromium, and arsenic. Results obtained indicate that chukanovite is a prevalent secondary precipitate in the PRBs. Laboratory experiments on high-purity chukanovite separates were carried out to constrain the room-temperature solubility for this mineral. An estimated Gibbs energy of formation ({Delta}{sub f}G{sup o}) for chukanovite is - 1174.4 {+-} 6 kJ/mol. A mineral stability diagram is consistent with observations from the field. Water chemistry from the three reactive barriers falls inside the predicted stability field for chukanovite, at inorganic carbon concentrations intermediate to the stability fields of siderite and ferrous hydroxide. These new data will aid in developing better predictive models of mineral accumulation in zerovalent iron PRBs.

  11. Utilization of phosphogypsum in tannery sludge stabilization and evaluation of the radiological impact.

    PubMed

    Pantazopoulou, E; Zebiliadou, O; Noli, F; Mitrakas, M; Samaras, P; Zouboulis, A

    2015-03-01

    The current global trend towards increasingly stringent environmental standards and efforts for efficient utilization and re-use of available by-products and/or wastes, favors the use of low-cost sorbent materials for the treatment of heavy metal-contaminated solid wastes. In this study, the stabilization of tannery sludge, produced from the physicochemical and biological treatment of tannery wastewaters, was examined by the addition of phosphogypsum (PG) at a ratio of 1:1. Characterization of the tannery sludge leachates showed high amounts of chromium which exceeded the acceptable level for disposal in non-hazardous waste landfills, while the dissolved organic carbon (DOC) concentrations exceeded the limits for disposal in landfills for hazardous wastes, according to the EU Decision 2003/33/EC. Leachates of the waste stabilized with PG presented chromium and DOC concentrations below the regulation limits for disposal in landfills for non-hazardous wastes. Moreover, mixing PG with tannery sludge resulted in a stabilized waste with reduced radioactivity. PMID:25432294

  12. Electron launching voltage monitor

    DOEpatents

    Mendel, C.W.; Savage, M.E.

    1992-03-17

    An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors. 5 figs.

  13. High voltage coaxial switch

    DOEpatents

    Rink, J.P.

    1983-07-19

    A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure. 3 figs.

  14. High voltage coaxial switch

    DOEpatents

    Rink, John P. (Los Alamos, NM)

    1983-07-19

    A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure.

  15. Electron launching voltage monitor

    DOEpatents

    Mendel, Clifford W. (Albuquerque, NM); Savage, Mark E. (Albuquerque, NM)

    1992-01-01

    An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors.

  16. Voltage controlled current source

    DOEpatents

    Casne, Gregory M. (Pittsburgh, PA)

    1992-01-01

    A seven decade, voltage controlled current source is described for use in testing intermediate range nuclear instruments that covers the entire test current range of from 10 picoamperes to 100 microamperes. High accuracy is obtained throughout the entire seven decades of output current with circuitry that includes a coordinated switching scheme responsive to the input signal from a hybrid computer to control the input voltage to an antilog amplifier, and to selectively connect a resistance to the antilog amplifier output to provide a continuous output current source as a function of a preset range of input voltage. An operator controlled switch provides current adjustment for operation in either a real-time simulation test mode or a time response test mode.

  17. A Gating Charge Transfer Center in Voltage Sensors

    SciTech Connect

    Tao, X.; Lee, A; Limapichat, W; Dougherty, D; MacKinnon, R

    2010-01-01

    Voltage sensors regulate the conformations of voltage-dependent ion channels and enzymes. Their nearly switchlike response as a function of membrane voltage comes from the movement of positively charged amino acids, arginine or lysine, across the membrane field. We used mutations with natural and unnatural amino acids, electrophysiological recordings, and x-ray crystallography to identify a charge transfer center in voltage sensors that facilitates this movement. This center consists of a rigid cyclic 'cap' and two negatively charged amino acids to interact with a positive charge. Specific mutations induce a preference for lysine relative to arginine. By placing lysine at specific locations, the voltage sensor can be stabilized in different conformations, which enables a dissection of voltage sensor movements and their relation to ion channel opening.

  18. Geomagnetism and induced voltage

    NASA Astrophysics Data System (ADS)

    Abdul-Razzaq, W.; Biller, R. D.

    2010-07-01

    Introductory physics laboratories have seen an influx of conceptual integrated science over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it is initiated by the change in the magnetic flux due to the Earth's magnetic field and movement. This simple and enjoyable experiment will demonstrate how basic concepts in physics and geology can help us think about possible health effects due to the induced voltage.

  19. High voltage variable diameter insulator

    DOEpatents

    Vanacek, D.L.; Pike, C.D.

    1982-07-13

    A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

  20. Fiber-optic voltage measuring system

    NASA Astrophysics Data System (ADS)

    Ye, Miaoyuan; Nie, De-Xin; Li, Yan; Peng, Yu; Lin, Qi-Qing; Wang, Jing-Gang

    1993-09-01

    A new fibre optic voltage measuring system has been developed based on the electrooptic effect of bismuth germanium oxide (Bi4Ge3O12)crystal. It uses the LED as the light source. The light beam emitted from the light source is transmitted to the sensor through the optic fibre and the intensity of the output beam is changed by the applied voltage. This optic signal is transmitted to the PIN detector and converted to an electric signal which is processed by the electronic circuit and 8098 single chip microcomputer the output voltage signal obtained is directly proportional to the applied voltage. This paper describes the principle the configuration and the performance parameters of the system. Test results are evaluated and discussed.

  1. Voltage regulation in distribution networks with distributed generation

    NASA Astrophysics Data System (ADS)

    Blai?, B.; Uljani?, B.; Papi?, I.

    2012-11-01

    The paper deals with the topic of voltage regulation in distribution networks with relatively high distributed energy resources (DER) penetration. The problem of voltage rise is described and different options for voltage regulation are given. The influence of DER on voltage profile and the effectiveness of the investigated solutions are evaluated by means of simulation in DIgSILENT. The simulated network is an actual distribution network in Slovenia with a relatively high penetration of distributed generation. Recommendations for voltage control in networks with DER penetration are given at the end.

  2. Photoacoustic Evaluation of Sunscreen Stability: Wind, Water, and the Influence of the Substrates

    NASA Astrophysics Data System (ADS)

    Pinto, S. B.; Barja, P. R.

    2012-11-01

    Sunscreens are designed to protect the skin against damage caused by excessive exposure to ultraviolet radiation—ranging from sunburns and premature aging to skin cancer. The photoacoustic (PA) technique can be employed to analyze topical products like sunscreens. This study aims to characterize the response of commercially available sunscreens subjected to wind and water exposure and applied in two different substrates: pig ear skin and artificial skin (Vitroskin ® ). The light source of the experimental setup was a tungsten lamp (250 W) mechanically modulated at 11 Hz. Measurements employed a double-faced, open PA cell with a sapphire window on one side; the opposite side was closed by the sample itself. Initial measurements were performed: (i) before sunscreen application in the sample, and (ii) immediately after sunscreen application. The sample was then immersed in a saline solution for 3 s and exposed to the wind under ambient temperature for 30 min; after that, a new measurement was performed. This cycle was repeated each 30 min, up to a total time of 2 h. Fitting curves (Boltzmann type) for the time evolution of the PA signal were generated with the software Origin ® . After measurements, Vitroskin ® was found to be a more adequate substrate than pig skin in the analysis of sunscreen stability. Results obtained indicate that the stability is not dependent on the sun protection factor; measurements performed in Vitroskin ® show good stability of the topically applied products for up to 2 h after sunscreen application, with a fall of less than 40 % in the PA signal amplitude even after exposure to external agents (wind and water).

  3. Evaluation of microwave oven heating for prediction of drug-excipient compatibilities and accelerated stability studies.

    PubMed

    Schou-Pedersen, Anne Marie V; stergaard, Jesper; Cornett, Claus; Hansen, Steen Honor

    2015-05-15

    Microwave ovens have been used extensively in organic synthesis in order to accelerate reaction rates. Here, a set up comprising a microwave oven combined with silicon carbide (SiC) plates for the controlled microwave heating of model formulations has been applied in order to investigate, if a microwave oven is applicable for accelerated drug stability testing. Chemical interactions were investigated in three selected model formulations of drug and excipients regarding the formation of ester and amide reaction products. In the accelerated stability studies, a design of experiments (DoE) approach was applied in order to be able to rank excipients regarding reactivity: Study A: cetirizine with PEG 400, sorbitol, glycerol and propylene glycol. Study B: 6-aminocaproic acid with citrate, acetate, tartrate and gluconate. Study C: atenolol with citric, tartaric, malic, glutaric, and sorbic acid. The model formulations were representative for oral solutions (co-solvents), parenteral solutions (buffer species) and solid dosage forms (organic acids applicable for solubility enhancement). The DoE studies showed overall that the same impurities were generated by microwave oven heating leading to temperatures between 150C and 180C as compared to accelerated stability studies performed at 40C and 80C using a conventional oven. Ranking of the reactivity of the excipients could be made in the DoE studies performed at 150-180C, which was representative for the ranking obtained after storage at 40C and 80C. It was possible to reduce the time needed for drug-excipient compatibility testing of the three model formulations from weeks to less than an hour in the three case studies. The microwave oven is therefore considered to be an interesting alternative to conventional thermal techniques for the investigation of drug-excipient interactions during preformulation. PMID:25746946

  4. Evaluation of enhanced thermostability and operational stability of carbonic anhydrase from Micrococcus species.

    PubMed

    Bhattacharya, Abhishek; Shrivastava, Ankita; Sharma, Anjana

    2013-06-01

    Carbonic anhydrase (CA) was purified from Micrococcus lylae and Micrococcus luteus with 49.90 and 53.8 % yield, respectively, isolated from calcium carbonate kilns. CA from M. lylae retained 80 % stability in the pH and temperature range of 6.0-8.0 and 35-45 C, respectively. However, CA from M. luteus was stable in the pH and temperature range of 7.5-10.0 and 35-55 C, respectively. Cross-linked enzyme aggregates (CLEAs) raised the transition temperature of M. lylae and M. luteus CA up to 67.5 and 74.0 C, while the operational stability (T(1/20) of CA at 55 C was calculated to be 7.7 and 12.0 h, respectively. CA from both the strains was found to be monomeric in nature with subunit molecular weight and molecular mass of 29 kDa. Ethoxozolamide was identified as the most potent inhibitor based on both IC(50) values and inhibitory constant measurement (K(i)). The K(m) and V(max) for M. lylae CA (2.31 mM; 769.23 ?mol/mg/min) and M. luteus CA (2.0 mM; 1,000 ?mol/mg/min) were calculated from Lineweaver-Burk plots in terms of esterase activity. Enhanced thermostability of CLEAs alleviates its role in operational stability for application at an on-site scrubber. The characteristic profile of purified CA from Micrococcus spp. advocates its effective application in biomimetic CO(2) sequestration. PMID:23609906

  5. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain Area Nevada Nuclear Waste Site Investigation (NNWSI)

    SciTech Connect

    1995-09-30

    This report provides a summary of progress for the project {open_quotes}Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI).{close_quotes} A similar report was previously provided for the period of 1 October 1993 to 30 September 1994. The report initially covers the activities of the General Task and is followed by sections that describe the progress of the other ongoing Tasks which are listed below. Task 1: Quaternary Tectonics Task 3: Mineral Deposits, Volcanic Geology Task 4: Seismology Task 5: Tectonics Task 8: Basinal Studies.

  6. Quantitative evaluation of the stability and delivery of interleukin-1B by infusion.

    PubMed

    Visor, G C; Tsai, K P; Duffy, J; Miller, M D; Calderwood, T; Knepp, V M

    1990-01-01

    The stability and delivery of IL-1 beta has been characterized in a polypropylene based syringe pump infusion system and in polyvinyl chloride based infusion bags, at concentrations ranging from 100 ng/mL to 1 microgram/mL. At higher concentrations (1 microgram/mL), minimal drug loss was observed in both systems. At low doses (100 ng/mL) in the syringe-pump system, the addition of 1% human serum albumin was necessary to prevent significant drug absorption to the polypropylene drug reservoir. PMID:2370622

  7. Experimental Evaluation of Journal Bearing Stability and New Gas Wave Bearing Materials

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    1998-01-01

    A gas journal bearing, with a wavy surfaces was tested in a range of speeds up to 18,000 RPM to determine its stability in an unloaded condition as a function of the wave amplitude. The bearing, was 50 mm in diameter, 58 mm long and had 0.01 65 mm radial clearance. Three waves were created on the inner surface by deforming the bearing sleeve. The ratio of the wave amplitude to the radial clearance (the wave amplitude ratio) was varied from zero to 0.3.

  8. Organic solar cells: evaluation of the stability of P3HT using time-delayed degradation

    NASA Astrophysics Data System (ADS)

    Poh, Chung-How; Poh, Chung-Kiak; Bryant, Glenn; Belcher, Warwick; Dastoor, Paul

    2011-12-01

    Despite the fact that the performance of organic solar cells is generally susceptible to degradation by moisture exposure, there has been suggestion that the photoactive layer (P3HT) is surprisingly resilient. This work attempts to confirm the stability of P3HT as an organic solar cell material by deliberately introducing water into the photoactive layer. A dramatic step drop in device performance during cell characterization is observed approximately one day after the device has been fabricated. The time-delayed step drop in output efficiency strongly suggests that moisture has little effect on the P3HT conducting polymer.

  9. Teacher-Course Evaluation: A Longitudinal Study of Response Stability and Instrument Reliability.

    ERIC Educational Resources Information Center

    McCollester, Charles W.; And Others

    The temporal context within which a teacher and course evaluation (TCE) is completed did not appear to be of crucial importance in affecting TCE responses. A sample of students was asked to evaluate, initially as freshmen and retrospectively as seniors, a specific teacher and course. Additional data on the student's academic status characteristics

  10. An in vitro and in vivo toxicologic evaluation of a stabilized aloe vera gel supplement drink in mice.

    PubMed

    Sehgal, Inder; Winters, Wallace D; Scott, Michael; Kousoulas, Konstantine

    2013-05-01

    Aloe vera gel is increasingly consumed as a beverage dietary supplement. The purpose of this study was to determine potential toxicity of a stabilized aloe vera gel derived from the inner gel fillet and marketed as a drink. The gel juice was assessed through assays of genotoxicity in vivo and acute and subchronic toxicity in B6C3F1 mice. Aloe vera did not increase the SOS DNA repair response in Escherichia coli and at 1 and 0.25 it did not increase mutagenesis of Salmonella TA100 resulting in histidine biosynthesis. At 3 and 14days following acute exposure, male and female mice gavaged with the stabilized aloe gel had daily appearances, total body weight gain, selected organ weights, necropsy and hematology tests similar to control mice gavaged with water. After a 13-week aloe gel feed study, male and female mice evaluated by the same criteria as the acute study plus feed consumption and serum chemistry tests were found to be equivalent to control groups. These data indicate that a commercial stabilized aloe gel consumed as a beverage was not genotoxic or toxic in vivo. These results contrast with those obtained using preparations containing aloe latex phenolic compounds such as anthraquinones. PMID:23376510

  11. Optimization of microwave-assisted extraction of cottonseed oil and evaluation of its oxidative stability and physicochemical properties.

    PubMed

    Taghvaei, Mostafa; Jafari, Seid Mahdi; Assadpoor, Elham; Nowrouzieh, Shahram; Alishah, Omran

    2014-10-01

    Microwave assisted extraction (MAE) is a novel method, which can reduce the extraction time and solvent consumption. This study aimed to evaluate the influence of MAE on oxidative stability and physicochemical properties of cottonseed oil. We found that the optimum extraction conditions were: irradiation time 3.57 min; cottonseed moisture content 14% and cottonseed to solvent ratio 1:4, which resulted in an extraction efficiency of 32.6%, 46 ppm total phenolic content, 0.7% free fatty acids, peroxide value of 0.2 and 11.5 h of Rancimat oxidative stability at 110 C. GC analysis for MAE cottonseed oil determined palmitic acid (23.6%), stearic acid (2.3%), oleic acid (15.6%) and linoleic acid (55.1%), which were not significant different (P>0.05) than conventionally-extracted (control) cottonseed oil. MAE oil samples from whole cottonseed (without dehulling) had the greatest long-term stability, more than oil samples containing BHT. PMID:24799213

  12. Application of maltodextrin and gum Arabic in microencapsulation of saffron petal's anthocyanins and evaluating their storage stability and color.

    PubMed

    Mahdavee Khazaei, K; Jafari, S M; Ghorbani, M; Hemmati Kakhki, A

    2014-05-25

    In this work, anthocyanin stability and color of encapsulated freeze-dried saffron petal's extract with various matrices consisting gum Arabic (AG) and maltodextrin (M7 and M20) were studied. Total anthocyanins of powders and color parameters (a*, b*, L*, C, H and TCD) were measured immediately after production and during storage up to 10 weeks by pH differential method and computer vision, respectively. Different compounds of wall materials did not show any significant differences in terms of stabilizing anthocyanins (P<0.01) and no significant decrease in anthocyanin content of the powders was observed after storage. The efficiency order of wall materials considering total color differences (TCD) was AG>M20>M7. By evaluating 3D surface and Cox trace plots it was revealed that wall formulas which had the lowest amount of AG and highest amounts of M20 and M7 showed the lowest total color differences after storage (P<0.05). To conclude, microencapsulation by freeze drying could be recommended as a suitable method for stabilizing anthocyanins of saffron petal's extract. PMID:24708952

  13. Cryopreservation of Quercus suber somatic embryos by encapsulation-dehydration and evaluation of genetic stability.

    PubMed

    Fernandes, Pedro; Rodriguez, Eleazar; Pinto, Glória; Roldán-Ruiz, Isabel; De Loose, Marc; Santos, Conceição

    2008-12-01

    We describe an encapsulation and dehydration procedure for the cryopreservation of cork oak (Quercus suber L.) somatic embryos that resulted in at least 90% survival. Genetic stability of the regenerated material was assessed by flow cytometry (FCM), amplified fragment length polymorphisms (AFLP) and simple sequence repeats (SSR). Cryopreservation of embryogenic clusters involved encapsulation of each cluster in an alginate bead, followed by a 3-day culture in 0.7 M sucrose and subsequent desiccation to 25 or 35% water content (WC), followed by freezing in liquid nitrogen. Thawed, cryopreserved somatic embryos had high viability and exhibited long-term survival. No morphological differences were observed between somatic embryos desiccated to 25 and 35% WC. Analysis of DNA ploidy stability of control (i.e., encapsulated and dehydrated but not frozen) and cryopreserved material by flow cytometry showed no significant differences. Similarly, DNA-marker analyses (AFLPs and SSR) revealed no significant differences between control and cryopreserved samples at the DNA-sequence level. Nonetheless, because polymorphisms were found between control material and samples cryopreserved and desiccated to 25% WC, the 35% WC method is recommended for cryopreservation of this tissue type. Cryopreservation of Q. suber somatic embryos by this encapsulation-dehydration procedure has potential for use in long-term conservation programs. PMID:19193567

  14. Analysis and test evaluation of the dynamic response and stability of three advanced turboprop models

    NASA Technical Reports Server (NTRS)

    Bansal, P. N.; Arseneaux, P. J.; Smith, A. F.; Turnberg, J. E.; Brooks, B. M.

    1985-01-01

    Results of dynamic response and stability wind tunnel tests of three 62.2 cm (24.5 in) diameter models of the Prop-Fan, advanced turboprop, are presented. Measurements of dynamic response were made with the rotors mounted on an isolated nacelle, with varying tilt for nonuniform inflow. One model was also tested using a semi-span wing and fuselage configuration for response to realistic aircraft inflow. Stability tests were performed using tunnel turbulence or a nitrogen jet for excitation. Measurements are compared with predictions made using beam analysis methods for the model with straight blades, and finite element analysis methods for the models with swept blades. Correlations between measured and predicted rotating blade natural frequencies for all the models are very good. The IP dynamic response of the straight blade model is reasonably well predicted. The IP response of the swept blades is underpredicted and the wing induced response of the straight blade is overpredicted. Two models did not flutter, as predicted. One swept blade model encountered an instability at a higher RPM than predicted, showing predictions to be conservative.

  15. Using AIRS and IASI Data to Evaluate Absolute Radiometric Accuracy and Stability for Climate Applications

    NASA Technical Reports Server (NTRS)

    Aumann, Hartmut H.; Pagano, Thomas S.

    2008-01-01

    The creation of multi-decadal data sets for climate research requires better than 100 mK absolute calibration accuracy for the full range of spectral temperatures encountered under global conditions. Validation that this accuracy is achieved by the operational hyperspectral sounders from polar orbit is facilitated by comparing data from two instruments. Extreme radiometric calibration stability is critical to allow a long time series of noisy, but presumably long-term accurate truth measurements to be used for the validation of absolute accuracy at the 100 mK level. We use the RTGSST in the tropical oceans as ground truth. The difference between the AIRS derived sst2616 and the RTGSST based on six years of data shows a systematic cold bias of about 250 mK, but better than 4 mK/year stability. The double difference between AIRS and the RTGSST and IASI and the RTGSST with less than one year of data already allows statements at the 100 mK absolute level. It shows a 60 mK difference between the AIRS and the IASI calibration at 2616 cm-(sup 1) and 300 K, with a statistically insignificant 20 mK shift in six months.

  16. Critical evaluation of the unsteady aerodynamics approach to dynamic stability at high angles of attack

    NASA Technical Reports Server (NTRS)

    Hui, W. H.

    1985-01-01

    Bifurcation theory is used to analyze the nonlinear dynamic stability characteristics of an aircraft subject to single-degree-of-freedom. The requisite moment of the aerodynamic forces in the equations of motion is shown to be representable in a form equivalent to the response to finite amplitude oscillations. It is shown how this information can be deduced from the case of infinitesimal-amplitude oscillations. The bifurcation theory analysis reveals that when the bifurcation parameter is increased beyond a critical value at which the aerodynamic damping vanishes, new solutions representing finite amplitude periodic motions bifurcate from the previously stable steady motion. The sign of a simple criterion, cast in terms of aerodynamic properties, determines whether the bifurcating solutions are stable or unstable. For the pitching motion of flat-plate airfoils flying at supersonic/hypersonic speed and for oscillation of flaps at transonic speed, the bifurcation is subcritical, implying either the exchanges of stability between steady and periodic motion are accompanied by hysteresis phenomena, or that potentially large aperiodic departures from steady motion may develop.

  17. Voltage-Controlled Oscillator

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Integrated Component Systems, Inc. incorporated information from a NASA Tech Briefs article into a voltage-controlled oscillator it designed for a customer. The company then applied the technology to its series of phase-locked loop synthesizers, which offer superior phase noise performance.

  18. Geomagnetism and Induced Voltage

    ERIC Educational Resources Information Center

    Abdul-Razzaq, W.; Biller, R. D.

    2010-01-01

    Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it is…

  19. Geomagnetism and Induced Voltage

    ERIC Educational Resources Information Center

    Abdul-Razzaq, W.; Biller, R. D.

    2010-01-01

    Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it is

  20. Measuring Breakdown Voltage.

    ERIC Educational Resources Information Center

    Auer, Herbert J.

    1978-01-01

    The article discusses an aspect of conductivity, one of the electrical properties subdivisions, and describes a tester that can be shop-built. Breakdown voltage of an insulation material is specifically examined. Test procedures, parts lists, diagrams, and test data form are included. (MF)

  1. Evaluation of the thermal stability of a novel strain of live-attenuated mumps vaccine (RS-12 strain) lyophilized in different stabilizers.

    PubMed

    Jamil, Razieh Kamali; Taqavian, Mohammad; Sadigh, Zohreh-Azita; Shahkarami, Mohammad-Kazem; Esna-Ashari, Fatemeh; Hamkar, Rasool; Hosseini, Seyedeh-Marzieh; Hatami, Alireza

    2014-04-01

    The stability of live-attenuated viral vaccines is important for immunization efficacy. Here, the thermostabilities of lyophilized live-attenuated mumps vaccine formulations in two different stabilizers, a trehalose dihydrate-based stabilizer and a stabilizer containing sucrose, human serum albumin and sorbitol were investigated using accelerated stability tests at 4C, 25C and 37C at time points between 4h (every 4h for the first 24h) and 1 week. Even under the harshest storage conditions of 37C for 1 week, the 50% cell culture infective dose (CCID50) determined from titrations in Vero cells dropped by less than 10-fold using each stabilizer formulation and thus complied with the World Health Organization's requirements for the potency of live-attenuated mumps vaccines. However, as the half-life of the RS-12 strain mumps virus infectivity was lengthened substantially at elevated temperatures using the trehalose dihydrate (TD)-based stabilizer, this stabilizer is recommended for vaccine use. PMID:24462846

  2. Application of matrix singular value properties for evaluating gain and phase margins of multiloop systems. [stability margins for wing flutter suppression and drone lateral attitude control

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, V.; Newsom, J. R.

    1982-01-01

    A stability margin evaluation method in terms of simultaneous gain and phase changes in all loops of a multiloop system is presented. A universal gain-phase margin evaluation diagram is constructed by generalizing an existing method using matrix singular value properties. Using this diagram and computing the minimum singular value of the system return difference matrix over the operating frequency range, regions of guaranteed stability margins can be obtained. Singular values are computed for a wing flutter suppression and a drone lateral attitude control problem. The numerical results indicate that this method predicts quite conservative stability margins. In the second example if the eigenvalue magnitude is used instead of the singular value, as a measure of nearness to singularity, more realistic stability margins are obtained. However, this relaxed measure generally cannot guarantee global stability.

  3. Evaluation of a Cognitive Rehabilitation Protocol in HIV Patients with Associated Neurocognitive Disorders: Efficacy and Stability Over Time

    PubMed Central

    Livelli, Alessandro; Orofino, Gian Carlo; Calcagno, Andrea; Farenga, Mariana; Penoncelli, Donatella; Guastavigna, Marta; Carosella, Sinibaldo; Caramello, Pietro; Pia, Lorenzo

    2015-01-01

    The primary aim of the present study was to evaluate the efficacy and stability over time of a cognitive rehabilitation protocol (restorative and compensatory approach) in HIV/AIDS patients with HIV-associated Neurocognitive Disorder (HAND). At baseline, 32 HIV/AIDS patients (16 with and 16 without HAND) were assessed with a neuropsychological battery (i.e., pre-assessment) consisting of 22 tests covering eight cognitive domains. Then, the experimental group was administered over 4 months a cognitive rehabilitation protocol aimed at improving four cognitive domains by means of eight paper and pencil/computer-based exercises. The control group received guideline-adherent clinical care (i.e., standard of care). At the end of the cognitive treatment, both groups were re-administered the neuropsychological battery (i.e., post-assessment). Additionally, 6 months after post-assessment, the experimental group was given the same neuropsychological battery (i.e., follow up-assessment). In order to test the efficacy of the cognitive rehabilitation protocol, we compared between groups the results of the neuropsychological battery at the pre- and post-assessments. In order to evaluate the stability over time, the effects of the cognitive rehabilitation protocol was examined comparing within the experimental group the results of the neuropsychological battery at post- and follow up-assessments. Our results show that the two groups did not differ at the pre-assessment, but differed at post-assessment. Specifically, the experimental group showed a significant improvement in five domains (Learning and memory, Abstraction/executive functioning, Verbal fluency, Attention/working memory, and Functional), whereas the control group significantly worsened in the same domains. The improvement of the experimental group did not change in the follow up-assessment in two domains (Abstraction/executive functioning, Attention/working memory, and Functional). Overall, these findings support the efficacy and, to some extent, the stability over time of our cognitive rehabilitation protocol. PMID:26635558

  4. ISO 12189 standard for the preclinical evaluation of posterior spinal stabilization devices - II: A parametric comparative study.

    PubMed

    La Barbera, Luigi; Costa, Francesco; Villa, Tomaso

    2016-02-01

    The International Standardization Organization (ISO) 12189 standard was recently introduced to preclinically evaluate and compare the mechanical properties of posterior stabilization devices. This scenario presents some new significant steps ahead over the vertebrectomy model recommended by American Society for Testing and Materials (ASTM) F1717 standard: the modular anterior support allows for describing a closer scenario to the effective clinical use as well as to test very flexible and dynamic posterior stabilization devices. Despite these significant advantages, ISO 12189 received little attention in the literature. Anatomical parameters depending on the spinal level were compared to the published data or original measurements on biplanar stereoradiography on 13 patients. Other mechanical variables, describing the test set-up design, were considered and all parameters were investigated using a numerical parametric finite element model. Stress values were calculated by also considering their worst-case combination. The standard set-up represents quite well the anatomy of an instrumented average thoracolumbar segment. The parametric comparative analysis demonstrates a significant (even beyond +350%) maximum increase in the stress on the device, compared to the standard currently in use. The anterior support stiffness plays the most detrimental effect (maximum stress increases up to 396%). The initial precompression step has an important role in determining the final stress values achieved at peak load (up to +76%). Moreover, when combining these two contributions, an even higher stress increase may be achieved (up to 473%). Despite the other anatomical parameters playing a secondary role, their worst-case combination demonstrates that a device could potentially undergo higher stresses than those reached according to standard suggestions (maximum increase of 22.4% at L1). Any user/designer should be aware of these effects when using ISO 12189 standard for the preclinical evaluation of posterior spinal stabilization devices. PMID:26673809

  5. Evaluation of Reinforcement and Analysis of Stability of a High-Arch Dam Based on Geomechanical Model Testing

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Liu, Y. R.; Yang, Q.

    2015-03-01

    Reinforcement measures are often used in high-arch dams with complicated geological foundations. The geomechanical model test is an effective method to study the global stability of arch dams and to evaluate the reinforcement effects of foundation treatments. The block masonry technique was developed to simulate the jointed rock mass, tectonic discontinuities, and reinforcement measures. A tailor-made low-strength binder and small blocks were developed to simulate the strength and deformation of the jointed rock mass and discontinuities, respectively. We applied this technique to geomechanical model tests of the Dagangshan arch dam with and without foundation reinforcements. A rupture test was conducted, and the stress and displacement distribution of the dam and abutments were recorded; the failure mechanisms and processes were explored. The reinforcement effects of the foundation treatment were evaluated by comparing the test results of the models with and without foundation reinforcements. Our analysis indicates that foundation reinforcements can improve the stress distribution, decrease deformation, prevent slides, reduce fault movement, and improve the global stability of high-arch dams.

  6. Study on process development and property evaluation of sol-gel derived magnesia stabilized zirconia minispheres

    NASA Astrophysics Data System (ADS)

    Judes, J.; Kamaraj, V.

    2014-06-01

    In order to overcome limitations in the processing parameters of powder compaction method, a novel processing technique based on sol-gel route has been developed to produce near-net-shaped prototype fine zirconia minispheres with required properties that could potentially be used as grinding media. Impact of magnesia concentration and sintering temperature on the final product has been analyzed in detail. Zirconia minispheres have been characterized to establish a correlation between physical, structural and mechanical properties. Sintering temperature, soaking period, heating rate and viscosity of the sol apparently influence the characteristics of the magnesia stabilized zirconia minispheres. The phase identification, density variation, chemical decomposition, functional group specification, surface area, porosity, shrinkage and microstructural features of the dried and sintered final product have been studied. It has been observed that magnesia content, sintering temperature, density and the grain size of the sintered minispheres have a significant impact on the mechanical properties of the final product.

  7. Evaluation of Stability and Biological Activity of Solid Nanodispersion of Lambda-Cyhalothrin

    PubMed Central

    Cui, Bo; Feng, Lei; Pan, Zhenzhong; Yu, Manli; Zeng, Zhanghua; Sun, Changjiao; Zhao, Xiang; Wang, Yan; Cui, Haixin

    2015-01-01

    Pesticides are essential agrochemicals used to protect plants from diseases, pests and weeds. However, the formulation defects of conventional pesticides cause food toxicity and ecological environmental problems. In this study, a novel, efficient and environmentally friendly formulation of lambda-cyhalothrin, a solid nanodispersion, was successfully developed based on melt-emulsification and high-speed shearing methods. The solid nanodispersion presented excellent advantages over conventional pesticide formulations in such formulation functions as dispersibility, stability and bioavailability. The formulation is free of organic solvents, and the use of surfactant is reduced. Therefore, the application of the solid nanodispersion in crop production will improve efficacy and reduce the occurrence of both pesticide residues in food and environmental pollution from pesticides. PMID:26281043

  8. Ti-Ni Rods with Variable Stiffness for Spine Stabilization: Manufacture and Biomechanical Evaluation

    NASA Astrophysics Data System (ADS)

    Brailovski, Vladimir; Facchinello, Yann; Brummund, Martin; Petit, Yvan; Mac-Thiong, Jean-Marc

    2016-02-01

    A new concept of monolithic spinal rods with variable flexural stiffness is proposed to reduce the risk of adjacent segment degeneration and vertebral fracture, while providing adequate stability to the spine. The variability of mechanical properties is generated by locally annealing Ti-Ni shape memory alloy rods. Ten-minute Joule effect annealing allows the restoration of the superelasticity in the heated portion of the rod. Such processing also generates a mechanical property gradient between the heated and the unheated zones. A numerical model simulating the annealing temperature and the distributions of the mechanical properties was developed to optimize the Joule-heating strategy and to modulate the rod's overall flexural stiffness. Subsequently, the rod model was included in a finite element model of a porcine lumbar spine to study the effect of the rod's stiffness profiles on the spinal biomechanics.

  9. Transdermal microemulsions of Glycyrrhiza glabra L.: characterization, stability and evaluation of antioxidant potential.

    PubMed

    Mostafa, Dina M; Ammar, Nagwa M; Abd El-Alim, Sameh H; El-anssary, Amira A

    2014-03-01

    The purpose of the present study is to formulate Glycyrrhiza glabra root and rhizome aqueous ethanolic extract in microemulsion carrier systems intended for transdermal delivery of incorporated antioxidant actives, flavonoids and polyphenols. The results obtained reveal that the microemulsion system ME3 possesses optimum properties regarding drug content (flavonoids and polyphenols), viscosity, pH, particle size and polydispersity index, zeta potential, stability, permeation of actives and hence possesses high in vitro and ex vivo antioxidant efficacy. These results indicate also that this microemulsion shows approximately 13-fold higher ex vivo antioxidant capacity compared with the liquorice extract solution. In addition, the proposed microemulsion is simple to dispense, cost effective and provides high patient compliance and convenience because of simple topical application and avoidance of non-comfortable oral or parenteral administration. PMID:24028295

  10. Release profile and stability evaluation of optimized chitosan/alginate nanoparticles as EGFR antisense vector.

    PubMed

    Azizi, Ebrahim; Namazi, Alireza; Haririan, Ismaeil; Fouladdel, Shamileh; Khoshayand, Mohammad R; Shotorbani, Parisa Y; Nomani, Alireza; Gazori, Taraneh

    2010-01-01

    Chitosan/alginate nanoparticles which had been optimized in our previous study using two different N/P ratios were chosen and their ability to release epidermal growth factor receptor (EGFR) antisense was investigated. In addition, the stability of these nanoparticles in aqueous medium and after freeze-drying was investigated. In the case of both N/P ratios (5, 25), nanoparticles started releasing EGFR antisense as soon as they were exposed to the medium and the release lasted for approximately 50 hours. Nanoparticle size, shape, zeta potential, and release profile did not show any significant change after the freeze-drying process (followed by reswelling). The nanoparticles were reswellable again after freeze-drying in phosphate buffer with a pH of 7.4 over a period of six hours. Agarose gel electrophoresis of the nanoparticles with the two different N/P ratios showed that these nanoparticles could protect EGFR antisense molecules for six hours. PMID:20957167

  11. Evaluation of the stability of pure silica MCM-41 toward water vapor

    SciTech Connect

    Carrott, M.M.L.R.; Candeias, A.J.E.; Carrott, P.J.M.; Unger, K.K.

    1999-12-21

    Water vapor adsorption/desorption isotherms at 298 K and XRD measurements and nitrogen isotherms at 77 K before and after exposure to water vapor were determined on pure silica MCM-41 samples; samples had different pore widths and were prepared by different synthesis methods, including hydrothermal and room-temperature procedures. It was found that prolonged exposure to water vapor provoked structural alterations in all of the MCM-41 materials studied, the most significant effects being a loss of pore shape uniformity and a large decrease in pore size and, in consequence, pore volume. Analysis of the results suggests that these alterations are due to expansion of the pore walls as well as, in some cases, to a collapse involving rupture of the walls. It is also confirmed that silylation is effective in stabilizing the pore structure but only at the expense of much lower pore volume and pore width.

  12. Biological kinetics evaluation of anaerobic stabilization pond treatment of palm oil mill effluent.

    PubMed

    Wong, Yee Shian; Kadir, Mohd Omar A B; Teng, Tjoon Tow

    2009-11-01

    Biological kinetic (bio-kinetic) study of the anaerobic stabilization pond treatment of palm oil mill effluent (POME) was carried out in a laboratory anaerobic bench scale reactor (ABSR). The reactor was operated at different feed flow-rates of 0.63, 0.76, 0.95, 1.27, 1.9 and 3.8l of raw POME for a day. Chemical oxygen demand (COD) as influent substrates was selected for bio-kinetic study. The investigation showed that the growth yield (Y(G)), specific biomass decay (b), maximum specific biomass growth rate (mu(max)), saturation constant (K(s)) and critical retention time (Theta(c)) were in the range of 0.990 g VSS/g COD(removed) day, 0.024 day(-1), 0.524 day(-1), 203.433 g COD l(-1) and 1.908 day, respectively. PMID:19560338

  13. Comparative evaluation of multi-purpose solutions in the stabilization of tear lysozyme.

    PubMed

    Barniak, Vicki L; Burke, Susan E; Venkatesh, Srini

    2010-12-01

    The range and extent of tear proteins removed by various multi-purpose solutions has been investigated, but there is little information in the literature about their ability to prevent denaturation of tear proteins, particularly lysozyme. The purpose of this study was to determine the ability of Bausch+Lomb Biotrue multi-purpose solution and other care solutions to affect denaturation of lysozyme using a lysozyme activity assay. The test solutions used were: Biotrue multi-purpose solution, Bausch+Lomb renu() fresh, formerly ReNu MultiPlus(), Alcon OPTI-FREE RepleniSH, Alcon OPTI-FREE EXPRESS, CIBA VISION AQuify, and AMO COMPLETE Multi-Purpose Solution Easy Rub Formula. A phosphate-buffered saline (PBS) solution served as a control. The test and control solutions containing lysozyme were exposed to sodium dodecyl sulfate (SDS), a known denaturant of the enzyme. The assay was based on digestion of the cell wall of Micrococcus luteus in a suspension, a substrate sensitive to active lysozyme. Enzymatic activity against M. luteus was used to assess activity of lysozyme. The decrease in the turbidity of the cell wall suspension, a measure of relative enzyme activity, was determined by following the decrease in absorbance (at 450nm) over time using a spectrophotometer. Statistically significant greater stabilization of lysozyme was observed with Biotrue multi-purpose solution and renu fresh than with OPTI-FREE RepleniSH, OPTI-FREE EXPRESS, AQuify, COMPLETE Multi-Purpose Solution Easy Rub Formula, and a PBS control. The lysozyme activity assay revealed that Biotrue multi-purpose solution and renu fresh have the ability to stabilize lysozyme under conditions that typically denature the protein. PMID:21071258

  14. Phase stability and biological property evaluation of plasma sprayed hydroxyapatite coatings for orthopedic and dental applications.

    PubMed

    Vahabzadeh, Sahar; Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2015-04-01

    In this work we have investigated the effects of strontium (Sr) dopant on in vitro protein release kinetics and in vivo osteogenic properties of plasma sprayed hydroxyapatite (HA) coatings, along with their dissolution behavior. Plasma sprayed HA coatings are widely used in load-bearing implants. Apart from osseointegration, the new generation of HA coating is expected to deliver biomolecules and/or drugs that can induce osteoinduction. This paper reports the preparation of crystalline and amorphous HA coatings on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray, and their stability at different solution pH. Coatings prepared at 110 mm working distance from the nozzle showed an average Ca ion release of 18 and 90 ppm in neutral and acidic environments, respectively. Decreasing the working distance to 90 mm resulted in the formation of a coating with less crystalline HA and phases with higher solubility products, and consequently higher dissolution over 32 days. A 92% release of a model protein bovine serum albumin (BSA) in phosphate buffer with pH of 7.4 was measured for Sr-doped HA (Sr-HA) coating, while only a 72% release could be measured for pure HA coating. Distortion of BSA during adsorption on coatings revealed a strong interaction between the protein and the coating, with an increase in α-helix content. Osteoid formation was found on Sr-HA implants as early as 7 weeks post implantation compared to HA coated and uncoated Ti implants. After 12 weeks post implantation, osteoid new bone was formed on HA implants; whereas, bone mineralization started on Sr-HA samples. While no osteoid was formed on bare Ti surfaces, bone was completely mineralized on HA and Sr-HA coatings after 16 weeks post implantation. Our results show that both phase stability and chemistry can have a significant influence toward in vitro and in vivo response of HA coatings on Ti implants. PMID:25638672

  15. Development and validation of an evaporation duct model. Part II: Evaluation and improvement of stability functions

    NASA Astrophysics Data System (ADS)

    Ding, Juli; Fei, Jianfang; Huang, Xiaogang; Cheng, Xiaoping; Hu, Xiaohua; Ji, Liang

    2015-06-01

    This study aims to validate and improve the universal evaporation duct (UED) model through a further analysis of the stability function ( ψ). A large number of hydrometeorological observations obtained from a tower platform near Xisha Island of the South China Sea are employed, together with the latest variations in ψ function. Applicability of different ψ functions for specific sea areas and stratification conditions is investigated based on three objective criteria. The results show that, under unstable conditions, ψ function of Fairall et al. (1996) (i.e., Fairall96, similar for abbreviations of other function names) in general offers the best performance. However, strictly speaking, this holds true only for the stability (represented by bulk Richardson number R iB) range -2.6 ⩽ R iB < -0.1; when conditions become weakly unstable (-0.1 ⩽ R iB < -0.01), Fairall96 offers the second best performance after Hu and Zhang (1992) (HYQ92). Conversely, for near-neutral but slightly unstable conditions (-0.01 ⩽ R iB < 0.0), the effects of Edson04, Fairall03, Grachev00, and Fairall96 are similar, with Edson04 being the best function but offering only a weak advantage. Under stable conditions, HYQ92 is the optimal and offers a pronounced advantage, followed by the newly introduced SHEBA07 (by Grachev et al., 2007) function. Accordingly, the most favorable functions, i.e., Fairall96 and HYQ92, are incorporated into the UED model to obtain an improved version of the model. With the new functions, the mean root-mean-square (rms) errors of the modified refractivity ( M), 0-5-m M slope, 5-40-m M slope, and the rms errors of evaporation duct height (EDH) are reduced by 21.65%, 9.12%, 38.79%, and 59.06%, respectively, compared to the classical Naval Postgraduate School model.

  16. Evaluation of TEM samples of an Mg-Al alloy prepared using FIB milling at the operating voltages of 10 kV and 40 kV.

    PubMed

    Kamino, Takeo; Yaguchi, Toshie; Kuroda, Yasushi; Ohnishi, Tsuyoshi; Ishitani, Tohru; Miyahara, Yuichi; Horita, Zenji

    2004-01-01

    Transmission electron microscopy (TEM) samples of an Mg-Al alloy has been prepared using a Ga-focused ion beam (FIB) milling at two different operating voltages of 10 kV and 40 kV to investigate the influence of the FIB energy on the sample quality. The fine structures of the samples have been studied using a high resolution TEM, and the concentration of the implanted Ga was analysed using an energy dispersive X-ray (EDX) analysis. The result of the TEM observation revealed that point defects were introduced to the sample finally milled at 40 kV but not at 10 kV. However, crystal lattice images and electron diffraction patterns were clearly observed on both the samples. The typical influence of the FIB energy was indicated in the elemental analysis. The relative Ga concentration in the thin sample finally milled at 10 kV was 1.0-2.0 at% that is less than half of 4.0-6.0 at% of the Ga concentration in the sample finally milled at 40 kV. A comparison between the experimental results of the Ga concentration measurement with simulation was also discussed. PMID:15582947

  17. Development of Automatic Voltage Regulator for Low Voltage Distribution Systems

    NASA Astrophysics Data System (ADS)

    Matsuda, Katsuhiro; Horikoshi, Kazuhiro; Seto, Toshiyuki; Iyama, Osamu; Kobayashi, Hiromu

    This paper presents the development of a new type of voltage regulator that can adequately maintain the voltage supplied to customers, dealing with the problem of voltage control along with the widespread use of photovoltaic power generation systems. The developed equipment is a pole-mounted type voltage regulator consisting of a step-down transformer that converts voltage from high to low and a series transformer for voltage compensation. The demonstration test conducted at the CRIEPI Akagi Test Center confirmed that the voltage control function of the developed voltage regulator is satisfactory based on the proposed control algorism. Also, simulation analysis, on the assumption of the clustered installation of photovoltaic power generation systems, confirmed that the introduction of the developed voltage regulator enables the system voltage to be adequately maintained and full photovoltaic power generation is possible without suppressing the output. It is anticipated that the developed voltage regulator is very effective in adequately regulating the voltage for low voltage distribution systems and gives an effective way for even more widespread photovoltaic power generation.

  18. Linking measurements of biodegradability, thermal stability and chemical composition to evaluate the effects of management on soil organic matter

    NASA Astrophysics Data System (ADS)

    Gregorich, Ed; Gillespie, Adam; Beare, Mike; Curtin, Denis; Sanei, Hamed; Yanni, Sandra

    2015-04-01

    The stability of soil organic matter (SOM) as it relates to resistance to microbial degradation has important implications for nutrient cycling, emission of greenhouse gases, and C sequestration. Hence, there is interest in developing new ways to accurately quantify and characterise the labile and stable forms of soil organic C. Our objectives in this study were to evaluate and describe relationships among the biodegradability, thermal stability and chemistry of SOM in soil under widely contrasting management regimes. Samples from the same soil under permanent pasture, an arable cropping rotation, and chemical fallow were fractionated (sand: 2000-50 ?m; silt: 50-5 ?m, and clay: < 5 ?m). Biodegradability of the SOM in size fractions and whole soils was assessed in a laboratory mineralization study. The chemical composition of SOM was characterized by X-ray absorption near-edge structure (XANES) spectroscopy at the K-edge and its thermal stability was determined by analytical pyrolysis using a Rock-Eval pyrolyser. The mineralization bioassay showed that whole soils and soil fractions under fallow were less susceptible to biodegradation than other managements and that sand-associated organic matter was significantly more susceptible than that in the silt or clay fractions. Analysis by XANES showed accumulation of carboxylates and strong depletion of amides (protein) and aromatics in the fallow whole soil. Moreover, protein depletion was most significant in the sand fraction of the fallow soil. Sand fractions in fallow and cropped soils were, however, enriched in plant-derived phenols, aromatics and carboxylates compared to the sand fraction of pasture soils. In contrast, ketones, which have been identified as products of microbially-processed organic matter, were slightly enriched in the silt fraction of the pasture soil. These data suggest reduced inputs and cropping restrict the decomposition of plant residues and, without supplemental N additions, protein-N in native SOM is significantly mineralized in fallow systems to meet microbial C mineralization demands. Analytical pyrolysis showed distinct differences in the thermal stability of SOM among the size fractions and management treatments; it also showed that the loss of SOM generally involved dehydrogenation. The temperature at which half of the C was pyrolyzed showed strong correlation with mineralizable C and thus provides solid evidence for a link between the biological and thermal stability of SOM.

  19. A low voltage ``railgun''

    NASA Astrophysics Data System (ADS)

    Starr, Stanley O.; Youngquist, Robert C.; Cox, Robert B.

    2013-01-01

    Due to recent advances in solid-state switches and ultra-capacitors, it is now possible to construct a "railgun" that can operate at voltages below 20 V. Railguns typically operate above a thousand volts, generating huge currents for a few milliseconds to provide thousands of g's of acceleration to a small projectile. The low voltage railgun described herein operates for much longer time periods (tenths of seconds to seconds), has far smaller acceleration and speed, but can potentially propel a much larger object. The impetus for this development is to lay the groundwork for a possible ground-based supersonic launch track, but the resulting system may also have applications as a simple linear motor. The system would also be a useful teaching tool, requiring concepts from electrodynamics, mechanics, and electronics for its understanding, and is relatively straightforward to construct.

  20. High Voltage Seismic Generator

    NASA Astrophysics Data System (ADS)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes constructed device very mobile. The project is still developing.

  1. Insulators for high voltages

    SciTech Connect

    Looms, J.S.T.

    1987-01-01

    This book describes electrical insulators for high voltage applications. Topics considered include the insulating materials, the manufacture of wet process porcelain, the manufacture of tempered glass, the glass-fibre core, the polymeric housing, the common problem - terminating an insulator, mechanical constraints, the physics of pollution flashover, the physics of contamination, testing of insulators, conclusions from testing, remedies for flashover, insulators for special cases, interference and noise, and the insulator of the future.

  2. HIGH VOLTAGE GENERATOR

    DOEpatents

    Schwemin, A.J.

    1959-03-17

    A generator is presented for producing relatively large currents at high voltages. In general, the invention comprises a plurality of capacitors connected in series by a plurality of switches alternately disposed with the capacitors. The circuit is mounted for movement with respect to contact members and switch closure means so that a load device and power supply are connected across successive numbers of capacitors, while the other capacitors are successively charged with the same power supply.

  3. High voltage pulse conditioning

    DOEpatents

    Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  4. High Voltage Connector

    SciTech Connect

    Kurita, C.H.; /Fermilab

    1987-03-06

    The originally designed high voltage connectors were to be made of brass. However, if treated like a Bellevile spring with the initially given dimensions, the stresses of the connector when crimped were calculated to be much higher than the yield stress of brass. Since the flange and outer diameters of the connector are to remain small, it was necessary to alter the other dimensions and choice of material in order to bring down the stresses applied to the connector.

  5. Understanding Skill in EVA Mass Handling. Volume 4; An Integrated Methodology for Evaluating Space Suit Mobility and Stability

    NASA Technical Reports Server (NTRS)

    McDonald, P. Vernon; Newman, Dava

    1999-01-01

    The empirical investigation of extravehicular activity (EVA) mass handling conducted on NASA's Precision Air-Bearing Floor led to a Phase I SBIR from JSC. The purpose of the SBIR was to design an innovative system for evaluating space suit mobility and stability in conditions that simulate EVA on the surface of the Moon or Mars. The approach we used to satisfy the Phase I objectives was based on a structured methodology for the development of human-systems technology. Accordingly the project was broken down into a number of tasks and subtasks. In sequence, the major tasks were: 1) Identify missions and tasks that will involve EVA and resulting mobility requirements in the near and long term; 2) Assess possible methods for evaluating mobility of space suits during field-based EVA tests; 3) Identify requirements for behavioral evaluation by interacting with NASA stakeholders;.4) Identify necessary and sufficient technology for implementation of a mobility evaluation system; and 5) Prioritize and select technology solutions. The work conducted in these tasks is described in this final volume of the series on EVA mass handling. While prior volumes in the series focus on novel data-analytic techniques, this volume addresses technology that is necessary for minimally intrusive data collection and near-real-time data analysis and display.

  6. Evaluation of Stability of Surface-Treated Mini-Implants in Diabetic Rabbits

    PubMed Central

    Oh, Nam-Hee; Kim, Eun-Young; Paek, Janghyun; Kook, Yoon-Ah; Jeong, Do-Min; Cho, Il-Sik; Nelson, Gerald

    2014-01-01

    Introduction. The purpose of this study was to investigate effects of surface treatment of mini-implants in diabetes-induced rabbits by comparing osseointegration around mini-implants. Methods. Twelve New Zealand white rabbits were divided into two groups (alloxan-induced diabetic group and control group). A total of 48 mini-implants were placed after four weeks of diabetic induction. 24 mini-implants were surface-treated with SLA (sandblasted with large grit, and acid etched) and the remaining 24 mini-implants had smooth surfaces. Four weeks after placement, 32 mini-implants were removed from 4 control and 4 diabetic rabbits. Insertion and removal torques were measured. The remaining 16 mini-implants from the two groups were histomorphometrically analyzed. Results. Maximum insertion torque showed no difference between diabetic and control groups, but total insertion energy was higher in control group. In surface-treated mini-implants, maximum removal torque was higher in both diabetic and control groups. Bone-implant contact (BIC) was increased in the control group when compared to the diabetic group. Surface-treated group had higher BIC than smooth surface group in both control and diabetic groups. However, there was no significantly statistical difference. Conclusions. Type 1 diabetes mellitus and surface treatment method of mini-implant affected primary stability of mini-implants. In addition, the use of orthodontic mini-implants in a diabetic patient is likely to show results similar to the healthy patient. PMID:24971093

  7. Oxidative stability and shelf-life evaluation of selected culinary oils.

    PubMed

    Kochhar, S Parkash; Henry, C Jeya K

    2009-01-01

    Four out of eight 'healthier' oils-namely, almond oil, avocado oil, hazelnut oil and macadamia nut oil-studied were rich sources of monounsaturated fatty acids like olive oil. Grape seed oil, rice barn oil (marketed recently), toasted sesame oil and walnut oil contained high levels of essential fatty acids. The order of oxidative stability determined by Rancimat measuring of the induction period at four temperatures (90 degrees C, 100 degrees C, 110 degrees C, and 120 degrees C) was found to be macadamia oil > rice bran oil approximately toasted sesame oil > avocado oil > almond oil > hazelnut oil > grape seed oil > walnut oil. High-level monounsaturated fatty acid oils gave a linear relationship between 100 times the reciprocal of the induction period against the total unsaturated fatty acid content obtained as %C18:2 + 0.08 x C18:1 + 2.08 x %C18:3, while the polyunsaturated fatty acid oils gave an exponential relationship. In the case of rice bran and hazelnut oils, shelf-life prediction from the extrapolation of the Arrhenius plots and the Q(10) factors was compared well with that of storage time given by the oil producers. In the cases of the other oils (with an exception of macadamia nut oil), the predicted shelf-lives were significantly lower than that of the storage times; especially, walnut oil (very prone to oxidation) gave 15-20 times lower shelf-life than the best-before storage life. PMID:19634067

  8. Alginate stabilized gold nanoparticle as multidrug carrier: Evaluation of cellular interactions and hemolytic potential.

    PubMed

    Dey, Soma; Sherly, M Caroline Diana; Rekha, M R; Sreenivasan, K

    2016-01-20

    This work delineates the synthesis of curcumin (Ccm) and methotrexate (MTX) conjugated biopolymer stabilized AuNPs (MP@Alg-Ccm AuNPs). The dual drug conjugated nano-vector was characterized by FTIR, (1)H NMR and UV-vis spectroscopic techniques. Hydrodynamic diameter and surface charge of the AuNPs were determined by DLS analysis and the spherical particles were visualized by TEM. MP@Alg-Ccm AuNPs exhibited improved cytotoxic potential against C6 glioma and MCF-7 cancer cell lines and was found to be highly hemocompatible. MP@Alg-Ccm AuNPs also exhibited active targeting efficiency against MCF-7 cancer cells due to the presence of "antifolate" drug MTX. Thus MP@Alg-Ccm AuNPs may find potential application in targeted combination chemotherapy for the treatment of cancer. The study is also interesting from the synthetic point of view because, here generation of AuNPs was done using "green chemical" alginate and dual drug conjugated AuNPs were created in two simple reaction steps using "green solvent" water. PMID:26572330

  9. Evaluating the Intracellular Stability and Unpacking of DNA Nanocomplexes by Quantum Dots-FRET

    PubMed Central

    Ho, Yi-Ping; Chen, Hunter H.; Leong, Kam W.; Wang, Tza-Huei

    2006-01-01

    We demonstrate a highly sensitive method to characterize the structural composition and intracellular fate of polymeric DNA nanocomplexes, formed by condensing plasmid DNA with cationic polymers through electrostatic interactions. Rational design of more efficient polymeric gene carriers will be possible only with mechanistic insights of the rate-limiting steps in the nonviral gene transfer process. To characterize the composition and binding dynamics of nanocomplexes, plasmid and its polymer carrier within nanocomplexes were labeled with quantum dots (QDs) and fluorescent organic dyes, respectively, as a donor and acceptor pair for fluorescence resonance energy transfer (FRET). The high signal-to-noise ratio in QD-mediated FRET enabled precise detection of discrete changes in nanocomplex state at the single-particle level, against various intracellular microenvironments. The distribution and unpacking of individual nanocomplexes within cells could thus be unambiguously followed by fluorescence microscopy. QD-FRET is a highly sensitive and quantitative method to determine the composition and dynamic stability of nanocomplexes during intracellular transport, where barriers to gene delivery may be identified to facilitate gene carrier optimization. PMID:17081642

  10. Determination of halonitromethanes and haloacetamides: an evaluation of sample preservation and analyte stability in drinking water.

    PubMed

    Liew, Deborah; Linge, Kathryn L; Joll, Cynthia A; Heitz, Anna; Charrois, Jeffrey W A

    2012-06-01

    Simultaneous quantitation of 6 halonitromethanes (HNMs) and 5 haloacetamides (HAAms) was achieved with a simplified liquid-liquid extraction (LLE) method, followed by gas chromatography-mass spectrometry. Stability tests showed that brominated tri-HNMs immediately degraded in the presence of ascorbic acid, sodium sulphite and sodium borohydride, and also reduced in samples treated with ammonium chloride, or with no preservation. Both ammonium chloride and ascorbic acid were suitable for the preservation of HAAms. Ammonium chloride was most suitable for preserving both HNMs and HAAms, although it is recommended that samples be analysed as soon as possible after collection. While groundwater samples exhibited a greater analytical bias compared to other waters, the good recoveries (>90%) of most analytes in tap water suggest that the method is very appropriate for determining these analytes in treated drinking waters. Application of the method to water from three drinking water treatment plants in Western Australia indicating N-DBP formation did occur, with increased detections after chlorination. The method is recommended for low-cost, rapid screening of both HNMs and HAAms in drinking water. PMID:22554415

  11. Evaluation of the stability indices for the thunderstorm forecasting in the region of Belgrade, Serbia

    NASA Astrophysics Data System (ADS)

    Vujovi?, D.; Paskota, M.; Todorovi?, N.; Vu?kovi?, V.

    2015-07-01

    The pre-convective atmosphere over Serbia during the ten-year period (2001-2010) was investigated using the radiosonde data from one meteorological station and the thunderstorm observations from thirteen SYNOP meteorological stations. In order to verify their ability to forecast a thunderstorm, several stability indices were examined. Rank sum scores (RSSs) were used to segregate indices and parameters which can differentiate between a thunderstorm and no-thunderstorm event. The following indices had the best RSS values: Lifted index (LI), K index (KI), Showalter index (SI), Boyden index (BI), Total totals (TT), dew-point temperature and mixing ratio. The threshold value test was used in order to determine the appropriate threshold values for these variables. The threshold with the best skill scores was chosen as the optimal. The thresholds were validated in two ways: through the control data set, and comparing the calculated indices thresholds with the values of indices for a randomly chosen day with an observed thunderstorm. The index with the highest skill for thunderstorm forecasting was LI, and then SI, KI and TT. The BI had the poorest skill scores.

  12. Evaluation of the Conformational Stability of Recombinant Desulfurizing Enzymes from a Newly Isolated Rhodococcus sp.

    PubMed

    Parravicini, Federica; Brocca, Stefania; Lotti, Marina

    2016-01-01

    Metabolic pathways of aerobic bacteria able to assimilate sulfur can provide biocatalysts for biodesulfurization of petroleum and of other sulfur-containing pollutants. Of major interest is the so-called "4S pathway," in that C-S bonds are specifically cleaved leaving the carbon skeleton of substrates intact. This pathway is carried out by four enzymes, named Dsz A, B, C, and D. In view of a possible application of recombinant Dsz enzymes in biodesulfurization treatments, we have investigated the structural features of enzymes cloned from a Rhodococcus strain isolated from polluted environmental samples and their resistance to temperature (20-95C) and to organic solvents (5, 10, and 20% v/v methanol, acetonitrile, hexane, and toluene). Changes in protein structures were assessed by circular dichroism and intrinsic fluorescence spectroscopy. We found that all Dsz proteins are unfolded by temperatures in the range 45-60C and by all solvents tested, with the most dramatic effect being produced by toluene. These results suggest that stabilization of the biocatalysts by protein engineering will be necessary for developing biodesulfurization technologies based on Dsz enzymes. PMID:26515071

  13. Epoxidized Soybean Oil: Evaluation of Oxidative Stabilization and Metal Quenching/Heat Transfer Performance

    NASA Astrophysics Data System (ADS)

    Simencio Otero, Rosa L.; Canale, Lauralice C. F.; Said Schicchi, Diego; Agaliotis, Eliana; Totten, George E.; Sánchez Sarmiento, Gustavo

    2013-07-01

    Vegetable and animal oils as a class of fluids have been used for hundreds of years, if not longer, as quenchants for hardening steel. However, when petroleum oils became available in the late 1800s and early 1900s, the use of these fluids as quenchants, in addition to their use in other industrial oil applications, quickly diminished. This was primarily, but not exclusively, due to their generally very poor thermal-oxidative instability and the difficulty for formulating fluid analogs with varying viscosity properties. Interest in the use of renewable fluids, such as vegetable oils, has increased dramatically in recent years as alternatives to the use of relatively non-biodegradable and toxic petroleum oils. However, the relatively poor thermal-oxidative stability has continued to be a significant reason for their general non-acceptance in the marketplace. Soybean oil (SO) is one of the most highly produced vegetable oils in Brazil. Currently, there are commercially produced epoxidized versions of SO which are available. The objective of this paper is to discuss the potential use of epoxidized SO and its heat transfer properties as a viable alternative to petroleum oils for hardening steel.

  14. Stability of Norwalk Virus Capsid Protein Interfaces Evaluated by in Silico Nanoindentation

    PubMed Central

    Boyd, Kevin J.; Bansal, Prakhar; Feng, Jun; May, Eric R.

    2015-01-01

    Norwalk virus causes severe gastroenteritis for which there is currently no specific anti-viral therapy. A stage of the infection process is uncoating of the protein capsid to expose the viral genome and allow for viral replication. A mechanical characterization of the Norwalk virus may provide important information relating to the mechanism of uncoating. The mechanical strength of the Norwalk virus has previously been investigated using atomic force microscopy (AFM) nanoindentation experiments. Those experiments cannot resolve specific molecular interactions, and therefore, we have employed a molecular modeling approach to gain insights into the potential uncoating mechanism of the Norwalk capsid. In this study, we perform simulated nanoindentation using a coarse-grained structure-based model, which provides an estimate of the spring constant in good agreement with the experimentally determined value. We further analyze the fracture mechanisms and determine weak interfaces in the capsid structure, which are potential sites to inhibit uncoating by stabilization of these weak interfaces. We conclude by identifying potential target sites at the junction of a weak proteinprotein interface. PMID:26284238

  15. Evaluation of the geological relationships to gas hydrate formation and stability

    SciTech Connect

    Krason, J.; Finley, P.

    1988-01-01

    The summaries of regional basin analyses document that potentially economic accumulations of gas hydrates can be formed in both active and passive margin settings. The principal requirement for gas hydrate formation in either setting is abundant methane. Passive margin sediments with high sedimentation rates and sufficient sedimentary organic carbon can generate large quantities of biogenic methane for hydrate formation. Similarly, active margin locations near a terrigenous sediment source can also have high methane generation potential due to rapid burial of adequate amounts of sedimentary organic matter. Many active margins with evidence of gas hydrate presence correspond to areas subject to upwelling. Upwelling currents can enhance methane generation by increasing primary productivity and thus sedimentary organic carbon. Structural deformation of the marginal sediments at both active and passive sites can enhance gas hydrate formation by providing pathways for migration of both biogenic and thermogenic gas to the shallow gas hydrate stability zone. Additionally, conventional hydrocarbon traps may initially concentrate sufficient amounts of hydrocarbons for subsequent gas hydrate formation.

  16. Co-surfactant free microemulsions: Preparation, characterization and stability evaluation for food application.

    PubMed

    Xu, Zhenbo; Jin, Jun; Zheng, Minying; Zheng, Yan; Xu, Xuebing; Liu, Yuanfa; Wang, Xingguo

    2016-08-01

    The aim of the study is to prepare co-surfactant free microalgal oil microemulsions and investigate their properties as well as processing stability for food application. The physicochemical characteristics of the microemulsions were investigated by dynamic light scattering (DLS), turbidity, conductivity, rheological measurements and transmission electron microscopy (TEM). Within the microemulsion region, when the surfactant to oil ratio was 9:1, the hydrodynamic diameter (Dh) was 18nm; when the surfactant to oil ratio was 7.5:1, the hydrodynamic diameter (Dh) was 50nm. Rheological studies proved that the microemulsion system was a pseudoplastic fluid, which followed a shear thinning flow behavior. The loss rate of docosahexaenoic acid (DHA) was less than 5%wt after ultra high temperature (UHT) and high temperature short time (HTST) thermal treatments. A high content of CaCl2 (10.0%wt) could not destroy the microemulsion system, and it could be stored at 4°C for two years. PMID:26988493

  17. Nanocarriers for antioxidant resveratrol: formulation approach, vesicle self-assembly and stability evaluation.

    PubMed

    Caddeo, Carla; Manconi, Maria; Fadda, Anna Maria; Lai, Francesco; Lampis, Sandrina; Diez-Sales, Octavio; Sinico, Chiara

    2013-11-01

    In this work we studied various nanoformulations of resveratrol in phospholipid vesicles. Conventional phophatidylcholine liposomes were prepared and characterized in parallel with PEVs (Penetration Enhancer-containing Vesicles) obtained by adding one of eight selected amphiphilic penetration enhancers (PEs; 0.2% w/v; HLB range 1-16) to the composition. All vesicles were around 100 nm, negatively charged (?-30 mV) and able to incorporate resveratrol in good yields (>74%). The structure and the lamellar self-organization of the vesicles were investigated by Transmission Electron Microscopy (TEM) and Small and Wide Angle X-ray Scattering (SWAXS). These analyses showed that the lamellarity of the vesicles depended on the formulation composition. This work also addressed the stability of our colloidal dispersions, which was measured by means of the analytical centrifuge LUMiSizer(): this procedure disclosed the absence of any demixing phenomena and estimated a 3- to 6-month shelf-life. Moreover, the antioxidant activity of resveratrol was determined by assessing its ability to scavenge free radicals (DPPH assay), and showed that it was not affected by the vesicular formulation. PMID:23838200

  18. Histomorphometric Evaluation of the Effects of Various Diode Lasers and Force Levels on Orthodontic Mini Screw Stability

    PubMed Central

    Isman, Eren; Taner, Lale; Kurkcu, Mehmet

    2015-01-01

    Abstract Objective The purpose of this study was to evaluate the effects of different laser dose and force levels on the stability of orthodontic mini screws used for anchorage, by histomorphometric analyses. Background data Low-level laser therapy speeds up blood flow, improves the mechanism of the revitalization processes, reduces the risk of infection, boosts metabolic activities, and accelerates the healing of the damaged tissue. Although there are many research studies about low-level laser therapy applications in a variety of areas, no investigations were found concerning mini screw stability using various laser dose levels with different force level applications. Methods Seventeen New Zealand white rabbits were used. A total of 68 cylindrical, self-drilling orthodontic mini screws were threaded at the fibula. Experimental subjects were divided into six groups; force application was not performed in the first three groups, whereas 150g of force was applied via nickel-titanium closed-coil springs placed between two mini screws in the other three groups. Measurements of the initial torque values (10?Ncm) were manipulated by a digital portable torque gauge. Various low-level laser doses were applied to the groups during the postoperative 10 days. After 4 weeks, bone-to-implant contact and cortical bone thickness were histomorphometrically analyzed. Results In the 150g force plus 20?J/cm2 dosage group, the highest bone-to-implant contact values were observed. (p<0.05) There were no statistically significant correlations between cortical bone thickness and bone-to-implant contact values; on the other hand, no significant difference was found among the same groups in terms of cortical bone thickness values (p>0.05). Conclusions Low-level laser therapy was noticed to induce the mini screwbone contact area. Low-level laser therapy may be a supplementary treatment method to increase the stability of the orthodontic mini screw. PMID:25594769

  19. Evaluation of the stability of fluoxetine in pluronic lecithin organogel and the determination of an appropriate beyond-use date.

    PubMed

    Peacock, Gina F; Sauvageot, Jurgita

    2014-01-01

    Fluoxetine is a commonly prescribed psychotropic medication for a variety of behavioral diagnoses in veterinary practice, and fluoxetine in Pluronic lecithin organogel has been used successfully in treating inappropriate urine spraying in felines. Historically, pharmacists have assigned a variety of beyond-use dates to extemporaneously compound drugs in Pluronic lecithin organogel. The objective of this study was to evaluate the stability of fluoxetine in Pluronic lecithin organogel over a period of six months and to determine an appropriate beyond-use date. A stability-indicating high-performance liquid chromatography method for fluoxetine in Pluronic lecithin organogel was validated in our laboratory. Fluoxetine-Pluronic lecithin organogel 50 mg/mL was prepared by a local compounding pharmacy and analyzed by high-performance liquid chromatograph at 0, 7, 14, 21, 28, 45, 60, 90, and 180 days. Physical stability was also assessed by visual observation. At each time point percent of initial concentration was calculated. The beyond-use date was determined as the time period that the samples maintained at least 90 percent of the initial concentration. At 180 days, the mean percent of initial concentration was 99 +/- 1.5 and, visually, the fluoxetine-Pluronic lecithin organogel retained the original color and consistency, without detectable separation of the different phases of Pluronic lecithin organogel. Since fluoxetine was physically stable and retained greater than 90 percent of initial concentration in Pluronic lecithin organogel for 180 days when stored at room temperature and protected from light, a beyond-use date of 180 days is appropriate. PMID:25306774

  20. METHOD FOR STABILIZING KLYSTRONS

    DOEpatents

    Magnuson, D.W.; Smith, D.F.

    1959-04-14

    High-frequency oscillators for the generation of microwaves, particularly a system for stabilizing frequency-modulated klystron oscillators of the reflex type, are described. The system takos advantage of the fact that a change in oscillator frequency will alter the normal phase displacement between the cavity and its modulator, creating an error voltage which is utilized to regulate the frequency of the oscillator and stabilize it.

  1. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L. (Martinez, CA); Pike, Chester D. (Pinole, CA)

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  2. Preparation and evaluation of 2-(allylthio)pyrazine-loaded lipid emulsion with enhanced stability and liver targeting.

    PubMed

    Jang, Jun-Hee; Kim, Chong-Kook; Choi, Han-Gon; Sung, Jung Hoon

    2009-03-01

    To develop 2-(allylthio)pyrazine (2-AP)-loaded lipid emulsion for parenteral administration, various lipid emulsions were prepared with soybean oil, lecithin, and other carriers using homogenization method, and their physical stabilities were investigated by measuring their droplet sizes. The pharmacokinetics and tissue distribution of 2-AP in lipid emulsion after intravenous administration to rats were evaluated compared with 2-AP in solution. 2-AP was lipophilic, sparingly water-soluble, and unstable in aqueous medium. The 2-AP-loaded lipid emulsion composed of 1% of 2-AP, 4% of soybean oil, 4% of lecithin, and 91% of water was physically and chemically stable for at least 8 weeks. It gave significantly faster clearance of 2-AP and higher affinity to the organs, especially the liver, compared with the 2-AP in solution, suggesting that it could selectively deliver 2-AP to the liver. Thus, the lipid emulsion with soybean oil and lecithin could be used as a potential dosage form with the liver-targeting property and enhanced stability of sparingly water-soluble 2-AP. PMID:19016100

  3. Evaluation of the Low-Speed Stability and Control Characteristics of a Mach 5.5 Waverider Concept

    NASA Technical Reports Server (NTRS)

    Hahne, David E.

    1997-01-01

    Static force and moment tests of a 0.062-scale model of a hypersonic vehicle study concept known as the LOFLYTE(TM) configuration were conducted in the Langley 12-Foot Low-Speed Tunnel. These tests looked primarily at the low-speed static stability and control characteristics of this configuration. Data were obtained over an angle-of-attack range of -5 deg. to 22 deg. at sideslip angles that ranged between -10 deg. and 10 deg. The tiperons were sized to provide enough pitch control to trim the vehicle up to alpha = 16 deg. with no more than 10 deg. of surface deflection and data obtained in this test showed that 10 deg. of tiperon deflection was nearly sufficient to trim the configuration up to the desired angle of attack. Because of the pitching-moment characteristics of the LOFLYTE(TM) configuration, there is a reasonably high level of unpowered trimmed lift at nominal takeoff and approach to landing that should allow for acceptable takeoff and landing speeds for this vehicle. Initial evaluation of the directional stability characteristics of this configuration showed a significant instability between alpha = 10 deg. and about alpha = 18 deg. This test determined that the cause of this instability was the interaction of the wing leading-edge vortex with the vertical tails. Moving the vertical tails either inboard or outboard from the baseline location eliminated this unfavorable interaction.

  4. Evaluation of disulfide bond position to enhance the thermal stability of a highly stable single domain antibody.

    PubMed

    Zabetakis, Dan; Olson, Mark A; Anderson, George P; Legler, Patricia M; Goldman, Ellen R

    2014-01-01

    Single domain antibodies are the small recombinant variable domains derived from camelid heavy-chain-only antibodies. They are renowned for their stability, in large part due to their ability to refold following thermal or chemical denaturation. In addition to refolding after heat denaturation, A3, a high affinity anti-Staphylococcal Enterotoxin B single domain antibody, possesses a melting temperature of ∼84°C, among the highest reported for a single domain antibody. In this work we utilized the recently described crystal structure of A3 to select locations for the insertion of a second disulfide bond and evaluated the impact that the addition of this second bond had on the melting temperature. Four double-disulfide versions of A3 were constructed and each was found to improve the melting temperature relative to the native structure without reducing affinity. Placement of the disulfide bond at a previously published position between framework regions 2 and 3 yielded the largest improvement (>6°C), suggesting this location is optimal, and seemingly provides a universal route to raise the melting temperature of single domain antibodies. This study further demonstrates that even single domain antibodies with extremely high melting points can be further stabilized by addition of disulfide bonds. PMID:25526640

  5. Comparative proteomics evaluation of plasma exosome isolation techniques and assessment of the stability of exosomes in normal human blood plasma.

    PubMed

    Kalra, Hina; Adda, Christopher G; Liem, Michael; Ang, Ching-Seng; Mechler, Adam; Simpson, Richard J; Hulett, Mark D; Mathivanan, Suresh

    2013-11-01

    Exosomes are nanovesicles released by a variety of cells and are detected in body fluids including blood. Recent studies have highlighted the critical application of exosomes as personalized targeted drug delivery vehicles and as reservoirs of disease biomarkers. While these research applications have created significant interest and can be translated into practice, the stability of exosomes needs to be assessed and exosome isolation protocols from blood plasma need to be optimized. To optimize methods to isolate exosomes from blood plasma, we performed a comparative evaluation of three exosome isolation techniques (differential centrifugation coupled with ultracentrifugation, epithelial cell adhesion molecule immunoaffinity pull-down, and OptiPrep(TM) density gradient separation) using normal human plasma. Based on MS, Western blotting and microscopy results, we found that the OptiPrep(TM) density gradient method was superior in isolating pure exosomal populations, devoid of highly abundant plasma proteins. In addition, we assessed the stability of exosomes in plasma over 90 days under various storage conditions. Western blotting analysis using the exosomal marker, TSG101, revealed that exosomes are stable for 90 days. Interestingly, in the context of cellular uptake, the isolated exosomes were able to fuse with target cells revealing that they were indeed biologically active. PMID:24115447

  6. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  7. Novel SiL evaluation of an optimal H? controller on the stability of a MAV in flight simulator

    NASA Astrophysics Data System (ADS)

    Sampaio, Rafael C. B.; Becker, Marcelo; Siqueira, Adriano A. G.; Freschi, Leonardo W.; Montanher, Marcelo P.

    This paper introduces a novel methodology to assist the evaluation of control algorithms for MAVs (Micro Aerial Vehicles) using Software-in-the-Loop (SiL) based flight simulation. The originality of this paper is to use Microsoft Flight Simulator (MSFS) as the environment to embed both the dynamic and graphic models of Ascending Technologies Pelican MAV flying robot. The resulting is a reliable model of the Pelican quadrotor. The full duplex communication between the virtual aircraft and the control algorithm is achieved by a custom C++/C software named FVMS (Flight Variables Management System), developed by Aerial Robots Team (ART), which is able to reach (read/write) a great number of flight variables from MSFS. To illustrate the effectiveness of such method, we first completely present FVMS architecture and main features. Later, the synthesis and then the application of the optimal H? robust control algorithm and its operation into the FVMS SiL context are explained. Regarding MAVs control evaluation, SiL simulation considerably contributes to save battery time, to ease control synthesis and prototyping and to prevent accidents during tests with the real robot. The final goal is to evaluate the stability of the Pelican platform in hovering tasks in flight simulation focusing on the efficiency of FVMS to properly run the optimal H? robust control algorithm. The SiL control of the MAV has proven FVMS capabilities, which may be extended to assist the design of other classes of controllers.

  8. CSER 00-003 Criticality Safety Evaluation report for PFP Magnesium Hydroxide Precipitation Process for Plutonium Stabilization Glovebox 3

    SciTech Connect

    LAN, J.S.

    2000-07-13

    This Criticality Safety Evaluation Report analyzes the stabilization of plutonium/uranium solutions in Glovebox 3 using the magnesium hydroxide precipitation process at PFP. The process covered are the receipt of diluted plutonium solutions into three precipitation tanks, the precipitation of plutonium from the solution, the filtering of the plutonium precipitate from the solution, the scraping of the precipitate from the filter into boats, and the initial drying of the precipitated slurry on a hot plate. A batch (up to 2.5 kg) is brought into the glovebox as plutonium nitrate, processed, and is then removed in boats for further processing. This CSER establishes limits for the magnesium hydroxide precipitation process in Glovebox 3 to maintain criticality safety while handling fissionable material.

  9. Comparison of JFTOT heater-tube-deposit rating methods for the evaluation of fuel thermal stability. Interim report

    SciTech Connect

    Morris, R.E.; Hazeltt, R.N.; McIlvaine, C.L.

    1987-12-29

    Quantification of deposits formed on heated metal surfaces is desirable for the evaluation of thermal stability by the JFTOT procedure. Empirical methods widely employed entail either visual comparisons or measurements of reflected light (TDR), both of which are sensitive to deposit color. The authors examined these and several other measurement techniques for JFTOT heater tubes and found that measurements of total carbon content by combustion were the most reliable. Two novel techniques, based on measurements of dielectric strength and interference effects of monochromatic light have been examined. It was found that the dielectric and interference methods correlated well with the combustion analyses and each other, while the TDR often yielded misleading results. The correlations between the various methods will be discussed in addition to the consequence of method choice on the interpretation of experimental data.

  10. Evaluation of the Effect of Ultraviolet Disinfection on Dimensional Stability of the Polyvinyl Silioxane Impressions. an in-Vitro Study

    PubMed Central

    Godbole, Surekha R; Dahane, Trupti M; Nimonkar, Sharayu V

    2014-01-01

    Introduction: Infection control is an important concept in the present day practice of dentistry. The prosthodontists are at an added risk of transmission because of the infection spreading through the contaminated lab equipments while working in the lab. The purpose of this study is to evaluate the effect of UV light disinfection on dimensional stability of polyvinyl siloxane impressions. Materials and Methods : Impressions were made in perforated custom tray. After polymerization of impression, half the samples were disinfected in UV light and remaining samples were not subjected to disinfection and poured in die stone which served as control group. Linear dimensions were measured on the cast with travelling microscope of 0.001accuracy. Result : The result showed that UV light disinfectant showed no significant dimensional changes on impressions. Conclusion: Hence, it can be safely used to disinfect impressions in clinical prosthodontic procedures. PMID:25386528

  11. Stability evaluation of hydrate-bearing sediments during thermally-driven hydrate dissociation

    NASA Astrophysics Data System (ADS)

    Kwon, T.; Cho, G.; Santamarina, J.; Kim, H.; Lee, J.

    2009-12-01

    Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations, or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. This study examined how thermal changes destabilize gas hydrate-bearing sediments. First, an analytical formulation was derived for predicting fluid pressure evolution in hydrate-bearing sediments subjected to thermal stimulation without mass transfer. The formulation captures the self-preservation behavior, calculates the hydrate and free gas quantities during dissociation, considering effective stress-controlled sediment compressibility and gas solubility in aqueous phase. Pore fluid pressure generation is proportional to the initial hydrate fraction and the sediment bulk stiffness; is inversely proportional to the initial gas fraction and gas solubility; and is limited by changes in effective stress that cause the failure of the sediment. Second, the analytical formulation for hydrate dissociation was incorporated as a user-defined function into a verified finite difference code (FLAC2D). The underlying physical processes of hydrate-bearing sediments, including hydrate dissociation, self-preservation, pore pressure evolution, gas dissolution, and sediment volume expansion, were coupled with the thermal conduction, pore fluid flow, and mechanical response of sediments. We conducted the simulations for a duration of 20 years, assuming a constant-temperature wellbore transferred heat to the surrounding hydrate-bearing sediments, resulting in dissociation of methane hydrate in the well vicinity. The model predicted dissociation-induced excess pore fluid pressures which resulted in a large volume expansion and plastic deformation of the sediments. Furthermore, when the critical stress was reached, localized shear failure of the sediment around the borehole was observed. In summary, the study indicates that the early stability of the sediment (i.e., when any hydrate is still present) is governed by the intensity of a heat source and the thermal conductivity of sediments. Later, the excess pore fluid pressure diffused from the dissociation region destabilizes the shallower sediments. In critical cases, an effective drainage path is necessary to prevent instability problems such as blow-up of sediments or buckling of a well.

  12. A Convenient Thiazole Orange Fluorescence Assay for the Evaluation of DNA Duplex Hybridization Stability

    PubMed Central

    Liang, Minmin; Liu, Xinrong; Nakamura, Kayoko; Chen, Xiangji; Cheng, Dengfeng; Liu, Guozheng; Dou, Shuping; Wang, Yi; Rusckowski, Mary; Hnatowich, Donald J.

    2016-01-01

    Objective A simple and rapid method for measuring the hybridization stability of duplexes of DNAs and other oligomers in different environments is described. When added to an oligomer duplex, the thiazole orange (TO) dye intercalates and in this state is fluorescent. Therefore, when duplex dissociation occurs, the release of TO results in a detectable change in fluorescence intensity. This assay was developed primarily to screen antisense oligomer duplexes that are stable in serum and in the cytoplasm but unstable in the presence of their target messenger RNA (mRNA). Methods The two antisense oligomers of this investigation were both 25 mer phosphorothioate (PS) DNAs, one directed against the RIα mRNA and the other directed against the mdr1 mRNA. The former duplex was first used in the solution studies, in most cases duplexed with a 16 mer phosphodiester (PO) complementary DNA (i.e., PS-DNA25/PO-cDNA16). Both duplexes were then tested in a series of cell studies using SK-BR-3 (RIα+), KB-G2 (mdr1++), and KB-31 (mdr1+/−) cells. Results Preliminary measurements in solution showed that maximum fluorescence was achieved when more than ten TO molecules were bound to each duplex. When a 25 mer PO-DNA or PO-RNA with the base sequence of the RIα mRNA was added, the dramatic change in fluorescence intensity that followed signified dissociation of the antisense DNA from the study duplex and reassociation with the target DNA. Kinetic measurements showed that this process was completed in about 3 min. Fluorescent measurements of SK-BR-3 (RIα+) cells incubated at 37°C with the anti-RIα study duplex over time showed a maximum at the point where the loss of fluorescence due to dissociation of the study duplex, probably by an antisense mechanism, began to dominate over the increasing fluorescence due to continuing cellular accumulation. A similar result was observed in the KB-G2 (mdr1+) cells incubated with the anti-mdr1 study duplex. Conclusions When study duplexes shown to be stable in serum were incubated with their target cells, the assay successfully detected evidence of dissociation, most likely by an antisense mechanism. Thus, a TO fluorescence assay has been developed that is capable of detecting the dissociation of DNA duplexes. PMID:19444399

  13. Evaluation of the geological relationships to gas hydrate formation and stability

    SciTech Connect

    Not Available

    1985-01-01

    During the reported year we have enhanced our knowledge on and gained considerable experience in assessment of the gas hydrate resources in the offshore environments. Specifically, we have learned and gained experience in the following: Efficiently locating data sources, including published literature and unpublished information. We have established personal communication extremely critical in data accessability and acquisition. We have updated information pertinent to gas hydrate knowledge, also based on thorough study and evaluation of most Russian literature and additional publications in languages other than English. Besides critical evaluation of widely spread literature, in many cases our reports include previously unpublished information (e.g. BSRs from the Gulf of Mexico). The assessment of the gas resources potential associated with the gas hydrates, although in most cases at a low level of confidence, appears also very encouraging for further, more detailed, study. We are also confident that, because of the present reports' format, new data and a concept-oriented approach, the result of our study will be of strong interest to various industries, research institutions and numerous governmental agencies.

  14. Power supply design for the filament of the high-voltage electron accelerator

    NASA Astrophysics Data System (ADS)

    Zhang, Lige; Yang, Lei; Yang, Jun; Huang, Jiang; Liu, Kaifeng; Zuo, Chen

    2015-12-01

    The filament is a key component for the electron emission in the high-voltage electron accelerator. In order to guarantee the stability of the beam intensity and ensure the proper functioning for the power supply in the airtight steel barrel, an efficient filament power supply under accurate control is required. The paper, based on the dual-switch forward converter and synchronous rectification technology, puts forward a prototype of power supply design for the filament of the high-voltage accelerator. The simulation is conducted with MATLAB-Simulink on the main topology and the control method. Loss analysis and thermal analysis are evaluated using the FEA method. Tests show that in this prototype, the accuracy of current control is higher than 97.5%, and the efficiency of the power supply reaches 87.8% when the output current is 40 A.

  15. An evaluation of prediction accuracy and stability of a new vegetation index for estimating vegetation leaf area index

    NASA Astrophysics Data System (ADS)

    Jiang, Hailing; Zhang, Lifu; Yang, Hang; Chen, Xiaoping; Wang, Shudong; Li, Xueke; Liu, Kai

    2014-11-01

    LAI is a crucial parameter and a basic quantity indicating crop growth situation. Empirical models comprising spectral indices (SIs) and LAI have widely been applied to the retrieval of LAI. SI method already has exhibited feasibility in the estimation of vegetation LAI. However, it is largely subject to the inconsistency from different remote sensors which have varied specifications, such as spectral response features and central wavelength. To address this issue, a new vegetation index (VIUPD) based on the universal pattern decomposition method was proposed. It is expressed as a linear sum of the pattern decomposition coefficients and features in sensor-independency. The aim of this study was to evaluate the prediction accuracy and stability of VIUPD for estimating LAI, compared with three other common-used SIs. In this study, the measured spectra were resampled to simulated TM multispectral data and Hyperion hyperspectral data respectively, using the Gaussian spectral response function. The three typical SIs chosen were including NDVI, TVI and MCARI, which were constructed with the sensitive bands to the LAI. Finally, the regression equations between four selected SIs and LAI were established. The best index evaluated using the simulated TM data was VIUPD which exhibits the best correlation with LAI (R2=0.92) followed by NDVI (R2=0.80). For the simulated Hyperion data, VIUPD again ranks first with R2=0.89, followed by TVI (R2=0.63). Meanwhile, the consistence of VIUPD also was studied based on simulated TM and Hyperion sensor data and the R2 reached to 0.95. It is demonstrated that VIUPD has the best accuracy and stability to estimate LAI of winter wheat whether using simulated TM data or Hyperion data, which reaffirms that VIUPD is comparatively sensor independent.

  16. Evaluation of the BD Vacutainer RST blood collection tube for routine chemistry analytes: clinical significance of differences and stability study

    PubMed Central

    Kocijancic, Marija; Cargonja, Jelena; Delic-Knezevic, Alma

    2014-01-01

    Introduction: Preanalytical variables account for most of laboratory errors. There is a wide range of factors that affect the reliability of laboratory report. Most convenient sample type for routine laboratory analysis is serum. BD Vacutainer Rapid Serum Tube (RST) (Becton, Dickinson and Company, Franklin Lakes, NJ, USA) blood collection tube provides rapid clotting time allowing fast serum separation. Our aim was to evaluate the comparability of routine chemistry parameters in BD Vacutainer RST blood collection tube in reference with the BD Vacutainer Serum Separating Tubes II Advance Tube (SST) (Becton, Dickinson and Company, Franklin Lakes, NJ, USA). Materials and methods: Blood specimens were collected from 90 participants for evaluation on its results, clotting time and stability study of six routine biochemistry parameters: glucose (Glu), aspartate aminotransferase (AST), alanine aminotransferase (ALT), calcium (Ca), lactate dehidrogenase (LD) and potassium (K) measured with Olympus AU2700 analyzer (Beckman Coulter, Tokyo, Japan). The significance of the differences between samples was assessed by paired t-test or Wilcoxon Matched-Pairs Rank test after checking for normality. Results: Clotting process was significantly shorter in the RSTs compared to SSTs (2.49 min vs. 19.47 min, respectively; P < 0.001). There was a statistically significant difference between the RST and SST II tubes for glucose, calcium and LD (P < 0.001). Differences for glucose and LD were also clinically significant. Analyte stability studies showed that all analytes were stable for 24 h at 4 C. Conclusions: Most results (except LD and glucose) from RST are comparable with those from SST. In addition, RST tube provides shorter clotting time. PMID:25351355

  17. Evaluating the Stability of Open Bite Treatments and Its Predictive Factors in the Retention Phase during Permanent Dentition

    PubMed Central

    Salehi, Parisa; Pakshir, Hamid Reza; Hoseini, Seyed Ali Reza

    2015-01-01

    Statement of the Problem Orthodontists often find challenges in treating the anterior open bite and maintaining the results. Purpose This retrospective study was aimed to evaluate the stability of corrected open bite in the retention phase during permanent dentition. Materials and Method A total number of 37 patients, including 20 males and 17 females, with the mean age of 182.1 years at the beginning of the treatment were studied after correction of the anterior open bite. Overbites of the patients were measured from their lateral cephalograms before (T1), at the end (T2) and at least 3 years after the end of the treatment in the presence of their fixed retainers (T3).The mean overbite changes and the number of patients with open bite, due to treatment relapse, at T3 were calculated. The relationship between the pre-treatment factors and the treatment relapse was assessed at T1 and T2. Also the effects of treatment methods, extraction and adjunctive use of removable appliances on the post-treatment relapse were evaluated. Results The mean overbite change during the post-treatment period was -0.460.7 mm and six patients (16.2%) had relapse in the follow-up recall. Cephalometric Jaraback index showed statistically significant, but weak correlation with overbite changes after the treatment (p= 0.035; r= -0.353). No significant difference was found between the extraction and non-extraction groups (p= 0.117) the use and the type of the removable appliances (p= 0.801). Conclusion Fixed retainers alone are insufficient for stabilizing the results of corrected open bite. The change of overbite in the retention phase could not be predicted from cephalometric measurements. Extraction and use of adjunctive removable appliance did not have any effect on the treatment relapse. PMID:25759854

  18. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  19. Modulation of BK channel voltage gating by different auxiliary ? subunits

    PubMed Central

    Contreras, Gustavo F.; Neely, Alan; Alvarez, Osvaldo; Gonzalez, Carlos; Latorre, Ramon

    2012-01-01

    Calcium- and voltage-activated potassium channels (BK) are regulated by a multiplicity of signals. The prevailing view is that different BK gating mechanisms converge to determine channel opening and that these gating mechanisms are allosterically coupled. In most instances the pore forming ? subunit of BK is associated with one of four alternative ? subunits that appear to target specific gating mechanisms to regulate the channel activity. In particular, ?1 stabilizes the active configuration of the BK voltage sensor having a large effect on BK Ca2+ sensitivity. To determine the extent to which ? subunits regulate the BK voltage sensor, we measured gating currents induced by the pore-forming BK ? subunit alone and with the different ? subunits expressed in Xenopus oocytes (?1, ?2IR, ?3b, and ?4). We found that ?1, ?2, and ?4 stabilize the BK voltage sensor in the active conformation. ?3 has no effect on voltage sensor equilibrium. In addition, ?4 decreases the apparent number of charges per voltage sensor. The decrease in the charge associated with the voltage sensor in ? ?4 channels explains most of their biophysical properties. For channels composed of the ? subunit alone, gating charge increases slowly with pulse duration as expected if a significant fraction of this charge develops with a time course comparable to that of K+ current activation. In the presence of ?1, ?2, and ?4 this slow component develops in advance of and much more rapidly than ion current activation, suggesting that BK channel opening proceeds in two steps. PMID:23112204

  20. Total dose effects on negative voltage regulator

    SciTech Connect

    Beaucour, J.; Carriere, T.; Gach, A.; Laxague, D. )

    1994-12-01

    Functional failure at low dose level (4 Krad(Si)) on voltage regulators (LM137) from different manufacturers are analyzed. Dose rate effects on parts hardness are evaluated, showing that lowering the dose rate degrade more the IC's in the range 55 rad(Si)/s--0,8 rad(Si)/s. A failure mechanism is proposed, mainly based on circuit analysis, voltage contrast measurements, local irradiation and local electrical measurements with probe station. A SPICE simulation was performed, providing quantitative information on the degradation. In the light of such a failure analysis and dose rate effects, practical implications on radiation assurance are discussed.

  1. Optical sensing in high voltage transmission lines using power over fiber and free space optics

    NASA Astrophysics Data System (ADS)

    Rosolem, João Batista; Bassan, Fabio Renato; Penze, Rivael Strobel; Leonardi, Ariovaldo Antonio; Fracarolli, João Paulo Vicentini; Floridia, Claudio

    2015-12-01

    In this work we propose the use of power over fiber (PoF) and free space optics (FSO) techniques to powering and receive signals from an electrical current sensor placed at high voltage potential using a pair of optical collimators. The technique evaluation was performed in a laboratorial prototype using 62.5/125 μm multimode fiber to study the sensitivity of the optical alignment and the influence of the collimation process in the sensing system wavelengths: data communication (1310 nm) and powering (830 nm). The collimators were installed in a rigid electric insulator in order to maintain the stability of transmission.

  2. Evaluating the potential of natural curcumin for oxidative stability of soybean oil.

    PubMed

    Eshghi, Naeeme; Asnaashari, Maryam; Khodaparast, Mohammad Hossein Haddad; Hosseini, Fereshteh

    2014-01-01

    The active substance of turmeric rhizome (curcumin) was extracted and identified with TLC and NMR. To evaluate the antioxidant efficiency of different concentrations of curcumin (120, 160 and 200 ppm) compared with tert-butylhydroquinone (TBHQ) (120 ppm) and ?-tocopherol (200 ppm) at two different temperatures (25C and 55C) under dark and light conditions during 90 days, the soybean oil with no added antioxidant was used as a food model, and its fatty acids profile was determined by GC. Results indicated that increasing concentration of curcumin leads to significantly decreased oxidation rates. The soybean oil containing curcumin at 25C in darkness with the lowest rate of increased peroxide value indicated the same antioxidant activity with ?-tocopherol and TBHQ. Moreover, the results of acid value and iodine value indicated that samples with curcumin were more effective in preventing oxidation at both temperatures compared with control. However, light did not have any significant effect. PMID:24702166

  3. Evaluation of chloropyromorphite stability in the rhizosphere of and in a sand culture.

    PubMed

    Abbaspour, Ali; Arocena, Joselito M

    2012-01-01

    Chloropyromorphite (Pb(PO)Cl), CP, is the most stable lead (Pb) mineral under normal environmental conditions and precipitates in Pb-contaminated soils by addition of phosphorous (P). A sand culture experiment was conducted to evaluate the efficiency of and roots to dissolve CP in the presence and in the absence of P source. The results showed that the rhizosphere of the plants had lower soluble P and Pb compared with the bulk, which can be attributed to a higher pH in the rhizosphere. Mineralogical transformations of CP in the root surface of the plants including lanarkite (PbSO.PbO) has been confirmed by X-ray diffraction and scanning electron microscopy techniques. Decrease in soluble P in the rhizosphere as a consequence of P uptake by the plant roots may be a reason for CP dissolution. This study indicates that the dissolution of CP can be promoted by rhizosphere processes. PMID:23099944

  4. Experimental Evaluation of Journal Bearing Stability and New Gas Bearing Material

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    2001-01-01

    It has been estimated that the noise levels in aircraft engine transmissions can be reduced by as much as 10 dB through the use of journal bearings. The potential benefits of lower noise levels include reduced wear, longer gear life and enhanced comfort for passengers and crew. Based on this concept the journal-thrust wave bearing was analyzed and its performance was evaluated. Numerical codes, developed over the past 30 years by Dr. Dimofte, were used to predict the performance of the bearing. The wave bearing is a fluid film bearing and therefore was analyzed using the Reynolds pressure equation. The formulation includes turbulent flow concepts and possesses a viscosity-temperature correction. The centrifugal growth of the bearing diameter and the deformation of the bearing under gear loads were also incorporated into the code. An experimental rig was developed to test the journal-thrust wave bearing.

  5. Longwall face stability: An evaluation of face sloughage. Report of Investigations/1993

    SciTech Connect

    Barczak, T.M.; Chase, F.E.; Organiscak, J.A.

    1993-01-01

    The U.S. Bureau of Mines report examines the causes and consequences of longwall face sloughage. Theoretical relationships were developed to evaluate mechanisms that produce sloughage. From these relationships, contributory factors were identified for further analysis in field efforts. A survey identified 12 mine sites with sloughage problems, and these were investigated. From these studies, it was determined that the depth of cover and mining height are the two most significant factors causing sloughage on longwall faces. Coalbed friability and cleat orientation also were found to be significant factors in promoting sloughage. It was concluded that sloughage is primarily a problem in thicker seams or seams with friable coalbeds, and that the problem is more severe as the depth of cover increases.

  6. Slope stability susceptibility evaluation parameter (SSEP) rating scheme - An approach for landslide hazard zonation

    NASA Astrophysics Data System (ADS)

    Raghuvanshi, Tarun Kumar; Ibrahim, Jemal; Ayalew, Dereje

    2014-11-01

    In this paper a new slope susceptibility evaluation parameter (SSEP) rating scheme is presented which is developed as an expert evaluation approach for landslide hazard zonation. The SSEP rating scheme is developed by considering intrinsic and external triggering parameters that are responsible for slope instability. The intrinsic parameters which are considered are; slope geometry, slope material (rock or soil type), structural discontinuities, landuse and landcover and groundwater. Besides, external triggering parameters such as, seismicity, rainfall and manmade activities are also considered. For SSEP empirical technique numerical ratings are assigned to each of the intrinsic and triggering parameters on the basis of logical judgments acquired from experience of studies of intrinsic and external triggering factors and their relative impact in inducing instability to the slope. Further, the distribution of maximum SSEP ratings is based on their relative order of importance in contributing instability to the slope. Finally, summation of all ratings for intrinsic and triggering parameter based on actual observation will provide the expected degree of landslide in a given land unit. This information may be utilized to develop a landslide hazard zonation map. The SSEP technique was applied in the area around Wurgessa Kebelle of North Wollo Zonal Administration, Amhara National Regional State in northern Ethiopia, some 490 km from Addis Ababa. The results obtained indicates that 8.33% of the area fall under Moderately hazard and 83.33% fall within High hazard whereas 8.34% of the area fall under Very high hazard. Further, in order to validate the LHZ map prepared during the study, active landslide activities and potential instability areas, delineated through inventory mapping was overlain on it. All active landslide activities and potential instability areas fall within very high and high hazard zone. Thus, the satisfactory agreement confirms the rationality of considered governing parameters, the adopted SSEP technique, tools and procedures in developing the landslide hazard map of the study area.

  7. Superconducting Fault Current Limiter for Transmission Voltage

    NASA Astrophysics Data System (ADS)

    Kraemer, Hans-Peter; Schmidt, Wolfgang; Cai, Hong; Gamble, Bruce; Madura, David; MacDonald, Tim; McNamara, Joe; Romanosky, Walther; Snitchler, Greg; Lallouet, Nicolas; Schmidt, Frank; Ahmed, Syed

    Within a collaboration of American Superconductor, Siemens, Nexans and Southern California Edison one electrical phase of a resistive superconducting fault current limiter for the 115 kV transmission voltage level has been designed and manufactured. The active part of the limiter consists of 63 bifilar coils made of 12 mm wide steel-stabilized YBCO conductor and is housed in a cryostat operated at 5 bar and 74 K. The first phase was completely assembled and successfully subjected to power switching tests and high voltage tests. The basic design of the system and the test results are reported. The work was funded in part by US-DOE under Contract Number DE-FC26-07NT43243.

  8. Development and evaluation of robust molecular markers linked to disease resistance in tomato for distinctness, uniformity and stability testing.

    PubMed

    Arens, Paul; Mansilla, Carmen; Deinum, Daniël; Cavellini, Laetitia; Moretti, André; Rolland, Sophie; van der Schoot, Hanneke; Calvache, David; Ponz, Fernando; Collonnier, Cécile; Mathis, René; Smilde, Diederik; Caranta, Carole; Vosman, Ben

    2010-02-01

    Molecular markers linked to phenotypically important traits are of great interest especially when traits are difficult and/or costly to be observed. In tomato where a strong focus on resistance breeding has led to the introgression of several resistance genes, resistance traits have become important characteristics in distinctness, uniformity and stability (DUS) testing for Plant Breeders Rights (PBR) applications. Evaluation of disease traits in biological assays is not always straightforward because assays are often influenced by environmental factors, and difficulties in scoring exist. In this study, we describe the development and/or evaluation of molecular marker assays for the Verticillium genes Ve1 and Ve2, the tomato mosaic virus Tm1 (linked marker), the tomato mosaic virus Tm2 and Tm2 ( 2 ) genes, the Meloidogyne incognita Mi1-2 gene, the Fusarium I (linked marker) and I2 loci, which are obligatory traits in PBR testing. The marker assays were evaluated for their robustness in a ring test and then evaluated in a set of varieties. Although in general, results between biological assays and marker assays gave highly correlated results, marker assays showed an advantage over biological tests in that the results were clearer, i.e., homozygote/heterozygote presence of the resistance gene can be detected and heterogeneity in seed lots can be identified readily. Within the UPOV framework for granting of PBR, the markers have the potential to fulfil the requirements needed for implementation in DUS testing of candidate varieties and could complement or may be an alternative to the pathogenesis tests that are carried out at present. PMID:19855951

  9. Evaluation of Cross-Protocol Stability of a Fully Automated Brain Multi-Atlas Parcellation Tool

    PubMed Central

    Liang, Zifei; He, Xiaohai; Ceritoglu, Can; Tang, Xiaoying; Li, Yue; Kutten, Kwame S.; Oishi, Kenichi; Miller, Michael I.; Mori, Susumu; Faria, Andreia V.

    2015-01-01

    Brain parcellation tools based on multiple-atlas algorithms have recently emerged as a promising method with which to accurately define brain structures. When dealing with data from various sources, it is crucial that these tools are robust for many different imaging protocols. In this study, we tested the robustness of a multiple-atlas, likelihood fusion algorithm using Alzheimer’s Disease Neuroimaging Initiative (ADNI) data with six different protocols, comprising three manufacturers and two magnetic field strengths. The entire brain was parceled into five different levels of granularity. In each level, which defines a set of brain structures, ranging from eight to 286 regions, we evaluated the variability of brain volumes related to the protocol, age, and diagnosis (healthy or Alzheimer’s disease). Our results indicated that, with proper pre-processing steps, the impact of different protocols is minor compared to biological effects, such as age and pathology. A precise knowledge of the sources of data variation enables sufficient statistical power and ensures the reliability of an anatomical analysis when using this automated brain parcellation tool on datasets from various imaging protocols, such as clinical databases. PMID:26208327

  10. Choosing low-voltage switchgear for hydro plants

    SciTech Connect

    Clemen, D.M.

    1996-06-01

    Low-voltage switchgear performs a vital function in distributing power to auxiliary electrical loads within hydropower plants. With careful evaluation, plant owners and engineers can select equipment that provides needed protection and has useful secondary features. This article discusses the desirable features of low-voltage switchgear, including tripping functions, breaker ratings, protective functions, and overall quality.

  11. Intermediate state trapping of a voltage sensor.

    PubMed

    Lacroix, Jrme J; Pless, Stephan A; Maragliano, Luca; Campos, Fabiana V; Galpin, Jason D; Ahern, Christopher A; Roux, Benot; Bezanilla, Francisco

    2012-12-01

    Voltage sensor domains (VSDs) regulate ion channels and enzymes by undergoing conformational changes depending on membrane electrical signals. The molecular mechanisms underlying the VSD transitions are not fully understood. Here, we show that some mutations of I241 in the S1 segment of the Shaker Kv channel positively shift the voltage dependence of the VSD movement and alter the functional coupling between VSD and pore domains. Among the I241 mutants, I241W immobilized the VSD movement during activation and deactivation, approximately halfway between the resting and active states, and drastically shifted the voltage activation of the ionic conductance. This phenotype, which is consistent with a stabilization of an intermediate VSD conformation by the I241W mutation, was diminished by the charge-conserving R2K mutation but not by the charge-neutralizing R2Q mutation. Interestingly, most of these effects were reproduced by the F244W mutation located one helical turn above I241. Electrophysiology recordings using nonnatural indole derivatives ruled out the involvement of cation-? interactions for the effects of the Trp inserted at positions I241 and F244 on the channel's conductance, but showed that the indole nitrogen was important for the I241W phenotype. Insight into the molecular mechanisms responsible for the stabilization of the intermediate state were investigated by creating in silico the mutations I241W, I241W/R2K, and F244W in intermediate conformations obtained from a computational VSD transition pathway determined using the string method. The experimental results and computational analysis suggest that the phenotype of I241W may originate in the formation of a hydrogen bond between the indole nitrogen atom and the backbone carbonyl of R2. This work provides new information on intermediate states in voltage-gated ion channels with an approach that produces minimum chemical perturbation. PMID:23183699

  12. Intermediate state trapping of a voltage sensor

    PubMed Central

    Lacroix, Jrme J.; Pless, Stephan A.; Maragliano, Luca; Campos, Fabiana V.; Galpin, Jason D.; Ahern, Christopher A.; Roux, Benot

    2012-01-01

    Voltage sensor domains (VSDs) regulate ion channels and enzymes by undergoing conformational changes depending on membrane electrical signals. The molecular mechanisms underlying the VSD transitions are not fully understood. Here, we show that some mutations of I241 in the S1 segment of the Shaker Kv channel positively shift the voltage dependence of the VSD movement and alter the functional coupling between VSD and pore domains. Among the I241 mutants, I241W immobilized the VSD movement during activation and deactivation, approximately halfway between the resting and active states, and drastically shifted the voltage activation of the ionic conductance. This phenotype, which is consistent with a stabilization of an intermediate VSD conformation by the I241W mutation, was diminished by the charge-conserving R2K mutation but not by the charge-neutralizing R2Q mutation. Interestingly, most of these effects were reproduced by the F244W mutation located one helical turn above I241. Electrophysiology recordings using nonnatural indole derivatives ruled out the involvement of cation-? interactions for the effects of the Trp inserted at positions I241 and F244 on the channels conductance, but showed that the indole nitrogen was important for the I241W phenotype. Insight into the molecular mechanisms responsible for the stabilization of the intermediate state were investigated by creating in silico the mutations I241W, I241W/R2K, and F244W in intermediate conformations obtained from a computational VSD transition pathway determined using the string method. The experimental results and computational analysis suggest that the phenotype of I241W may originate in the formation of a hydrogen bond between the indole nitrogen atom and the backbone carbonyl of R2. This work provides new information on intermediate states in voltage-gated ion channels with an approach that produces minimum chemical perturbation. PMID:23183699

  13. In Vivo Evaluation of Quantitative Percussion Diagnostics for Determining Implant Stability

    PubMed Central

    VanSchoiack, Lindsey R.; Shubayev, Veronica I.; Myers, Robert R.; Sheets, Cherilyn G.; Earthman, James C.

    2014-01-01

    Purpose A percussion instrument (Periometer, Perimetrics LLC, Newport Beach, CA, USA) and rat model were used to test the hypothesis: percussion diagnostics provides reliable, reproducible indications of osseointegration. Materials and Methods Titanium implants were placed in femurs of 36 Sprague-Dawley rats. Each animal was assigned to one of six groups of six defined by one of three time points (2, 4, or 8 weeks post-placement) and one of two treatments (MMP inhibitor or vehicle). Percussion testing was conducted three times/subject at implant placement and at one of the time points. For each time point, there was an experimental group that received daily intraperitoneal injections of GM6001, and a control group that received no MMP inhibitor. The percussion data consisted of loss coefficient (LC) values that characterize energy dissipation. Statistical analysis was performed on the LC values for two animal groups using the paired Student t test to assess differences as a function of time, and the independent t test to compare mean LC for the study groups at sacrifice (?=0.05). Histological evaluation using the osteogenic CD40 protein marker was also performed. Results A nearly significant difference in mean LC at the 2-week time point was observed between the two treatments with the GM6001 group having the higher value (p = 0.053). There was a greater difference between the mean LC values for the 4-week GM6001 and vehicle groups (p = 0.001). The histological evidence for subjects in these two groups confirmed reduction of osteogenesis at the implant interface after administration of the MMP inhibitor. Conclusions Lower vehicle LC values relative to the GM6001 therapeutic group were observed, consistent with the effect MMP inhibition has on matrix remodeling at the implant bone interface. This finding in conjunction with histological observations confirms that osseointegration can be monitored using percussion diagnostics. PMID:24066319

  14. Clinical evaluation of the modified Brostrom-Evans procedure to restore ankle stability.

    PubMed

    Girard, P; Anderson, R B; Davis, W H; Isear, J A; Kiebzak, G M

    1999-04-01

    The modified Brostrom procedure has become the standard for anatomic repair of symptomatic chronic lateral instability. However, it was our perception that this local tissue repair may fail eventually, particularly in patients that are overweight, hyperflexible, or are involved in strenuous work or athletic activity. This is a retrospective review of 21 lateral ankle reconstructions (20 patients) in which the modified Brostrom technique was augmented with a portion of the peroneus brevis tendon. All patients were interviewed at an average of 29.5 months (range, 14-56 months postsurgery). Fourteen patients also agreed to be evaluated by a physical therapist. No surgical complications were identified. American Orthopaedic Foot and Ankle Society ankle-hindfoot scores averaged 98.2. There was no significant difference in passive or active range of motion of plantarflexion or dorsiflexion when compared to the contralateral ankle. However, a statistically significant loss of inversion (passive, P = 0.011; active, P = 0.018) and eversion (passive, P = 0.004; active, P = 0.007) was noted when compared to the contralateral ankle. Measurement of isometric eversion strength, using a Cybex 340 Isokinetic device, and functional testing, using a lateral lunge test, revealed no significant loss of peroneal strength. The authors conclude that chronic lateral ankle instability in the general population can be successfully managed with a modified Brostrom procedure augmented with a portion of the peroneus brevis. The procedure remains technically simple and provides a greater static restraint for inversion stress without evidence of dramatic overtightening or loss of peroneal strength. PMID:10229281

  15. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

    PubMed

    Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

    2012-09-30

    This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.14410(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. PMID:22831997

  16. Three Year RSA Evaluation of Vitamin E Diffused Highly Cross-linked Polyethylene Liners and Cup Stability.

    PubMed

    Sillesen, Nanna H; Greene, Meridith E; Nebergall, Audrey K; Nielsen, Poul T; Laursen, Mogens B; Troelsen, Anders; Malchau, Henrik

    2015-07-01

    Vitamin E diffusion into highly cross-linked polyethylene (E-XLPE) is a method for enhancing oxidative stability of acetabular liners. The purpose of this study was to evaluate in vivo penetration of E-XLPE using radiostereometric analysis (RSA). Eighty-four hips were recruited into a prospective 10-year RSA. This is the first evaluation of the multicenter cohort after 3-years. All patients received E-XLPE liners (E1, Biomet) and porous-titanium coated cups (Regenerex, Biomet). There was no difference (P=0.450) in median femoral head penetration into the E-XLPE liners at 3-years comparing cobalt-chrome heads (-0.028mm; inter-quartile range (IQR) - 0.065 to 0.047) with ceramic heads (-0.043mm, IQR - 0.143to0.042). The 3-year follow-up indicates minimal E-XLPE liner penetration regardless of head material and minimal early cup movement. PMID:25754257

  17. ISO 12189 standard for the preclinical evaluation of posterior spinal stabilization devices - I: Assembly procedure and validation.

    PubMed

    La Barbera, Luigi; Villa, Tomaso

    2016-02-01

    The International Standardization Organization introduced standard 12189 for the preclinical evaluation of the mechanical reliability of posterior stabilization devices. The well-known vertebrectomy model formalized in standard F1717 by the American Society for Testing and Materials was modified with the introduction of a modular anterior support made up of three calibrated springs, which allows to describe a more realistic scenario, closer to the effective clinical use, as well to test even very flexible and dynamic posterior stabilization implants. Despite these important improvements, ISO 12189 received very little attention in the literature. The aim of the work is to provide a systematic procedure for the assembly and validation of a finite element model capable of describing the experimental test according to ISO 12189. The validated finite element model is able to catch very well the effective stiffness of the unassembled and assembled constructs (percentage differences <2% and <10%, respectively). As concern the assembled construct, the experimentally measured and predicted strains were found in a good agreement (R(2) > 0.75, root mean square error < 30%), but the procedure without precompression lead to much better results (R(2) > 0.96, root mean square error < 10%). Given the prediction errors of the assembled construct fall within the experimental range of repeatability, the finite element model can be systematically implemented to support the mechanical design of a variety of spinal implants, to quantitatively investigate the load-sharing mechanism, as well as to investigate the loading conditions set by ISO 12189 standard. PMID:26679431

  18. Oral premedication with pregabalin or clonidine for hemodynamic stability during laryngoscopy and laparoscopic cholecystectomy: A comparative evaluation

    PubMed Central

    Gupta, Kumkum; Sharma, Deepak; Gupta, Prashant K.

    2011-01-01

    Background: Hemodynamic responses of laryngoscopy and laparoscopy should be attenuated by the appropriate premedication, smooth induction, and rapid intubation. The present study evaluated the clinical efficacy of oral premedication with pregabalin or clonidine for hemodynamic stability during laryngoscopy and laparoscopic cholecystectomy. Methods: A total of 180 healthy adult consented patients aged 35 to 52 years with American Society of Anesthesiologist (ASA) physical status I and II of both gender, who met the inclusion criteria for elective laparoscopic cholecystectomy, were randomized to receive placebo Group I, pregabalin (150 mg) Group II, or clonidine (200 ?g) Group III, given 75 to 90 minutes before surgery as oral premedication. All groups were compared for preoperative sedation and anxiety level along with changes of heart rate and mean arterial pressure prior to premedication, before induction, after laryngoscopy, pneumoperitoneum, release of carbon dioxide, and extubation. Intraoperative analgesic drug requirement and any postoperative complications were also recorded. Results: Pregabalin and clonidine proved to have sedative and anxiolytic effects as oral premedicants and decreased the need of intraoperative analgesic drug requirement. Clonidine was superior to pregabalin for attenuation of the hemodynamic responses to laryngoscopy and laparoscopy, but it increased the incidence of intra-and postoperative bradycardia. No significant differences in the parameters of recovery were observed between the groups. None of the premedicated patient has suffered from any postoperative side effects. Conclusion: Oral premedication with pregabalin 150 mg or clonidine 200 ?g causes sedation and anxiolysis with hemodynamic stability during laryngoscopy and laparoscopic cholecystectomy, without prolongation of recovery time and side effects. PMID:21804800

  19. Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig.

  20. High voltage isolation transformer

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C. H.; Ruitberg, A. P. (Inventor)

    1985-01-01

    A high voltage isolation transformer is provided with primary and secondary coils separated by discrete electrostatic shields from the surfaces of insulating spools on which the coils are wound. The electrostatic shields are formed by coatings of a compound with a low electrical conductivity which completely encase the coils and adhere to the surfaces of the insulating spools adjacent to the coils. Coatings of the compound also line axial bores of the spools, thereby forming electrostatic shields separating the spools from legs of a ferromagnetic core extending through the bores. The transformer is able to isolate a high constant potential applied to one of its coils, without the occurrence of sparking or corona, by coupling the coatings, lining the axial bores to the ferromagnetic core and by coupling one terminal of each coil to the respective coating encasing the coil.