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1

Wind Power Plant Voltage Stability Evaluation: Preprint  

SciTech Connect

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.

Muljadi, E.; Zhang, Y. C.

2014-09-01

2

Memristor-integrated voltage-stabilizing supercapacitor system.  

PubMed

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

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

2014-08-01

3

Online voltage stability assessment of load centers by using neural networks  

Microsoft Academic Search

This paper presents a neural network based method for evaluating online voltage stability conditions for a selected load center of an electric power system. Starting with a dynamic model of the system, a suitable index is defined to evaluate the proximity of the power network to voltage collapse. Then, a three-layer feedforward neural network is trained to give, as output

D. Salatino; R. Sbrizzai; M. Trovato; M. La Scala

1995-01-01

4

Voltage, Stability and Diffusion Barrier Differences between Sodium-ion and Lithium-ion Intercalation Materials  

E-print Network

To evaluate the potential of Na-ion batteries, we contrast in this work the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties—voltage, phase stability and diffusion ...

Ong, Shyue Ping

5

Pore stability and gating in voltage-activated calcium channels  

PubMed Central

Calcium channel family members activate at different membrane potentials, which enables tissue specific calcium entry. Pore mutations affecting this voltage dependence are associated with channelopathies. In this review we analyze the link between voltage sensitivity and corresponding kinetic phenotypes of calcium channel activation. Systematic changes in hydrophobicity in the lower third of S6 segments gradually shift the activation curve thereby determining the voltage sensitivity. Homology modeling suggests that hydrophobic residues that are located in all four S6 segments close to the inner channel mouth might form adhesion points stabilizing the closed gate. Simulation studies support a scenario where voltage sensors and the pore are essentially independent structural units. We speculate that evolution designed the voltage sensing machinery as robust “all-or-non” device while the varietys of voltage sensitivities of different channel types was accomplished by shaping pore stability. PMID:18849656

Hering, Steffen; Beyl, Stansilav; Stary, Anna; Kudrnac, Michaela; Hohaus, Annette; Guy, H. Robert; Timin, Eugen

2011-01-01

6

Long term voltage stability analysis for small disturbances  

E-print Network

This dissertation attempts to establish an analytical and comprehensive framework to deal with two critical challenges associated with voltage stability analysis: 1. To study the new competitive environment appropriately and give more incentive...

Men, Kun

2009-05-15

7

Voltage stability analysis using static and dynamic approaches  

Microsoft Academic Search

The authors discuss voltage stability analysis of power systems using static and dynamic techniques. Using a small test system, results of time domain simulations are presented to clarify the phenomenon of voltage instability and to better understand modeling requirements. The same system is then analyzed using a static approach in which modal analysis is performed using system conditions, or snapshots,

G. K. Morison; B. Gao; P. Kundur

1993-01-01

8

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

PubMed Central

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

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

2015-01-01

9

High voltage stability performance of a gamma ray detection device  

SciTech Connect

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.

Abdullah, Nor Arymaswati; Lombigit, Lojius; Rahman, Nur Aira Abd [Technical Support Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia)

2014-02-12

10

Application of SMES in wind farm to improve voltage stability  

NASA Astrophysics Data System (ADS)

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.

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

2008-09-01

11

Study on Static Voltage Stability Assessment for Load Center Area  

Microsoft Academic Search

The static voltage stability assessment (VSA) for a typical load center is discussed in this paper. Two indices are proposed for the static VSA of load centers. Moreover, the corresponding criteria are made for Beijing power system (BPS). A framework is developed in this paper to deal with the contingencies for the transmission interface and local generators which are critical

J. F. Shang; J. H. Zhang; S. Li

2006-01-01

12

Impact of wind generation on voltage stability in low-voltage distribution networks  

Microsoft Academic Search

This paper aims to study and provide understanding on the impact of wind generation on voltage stability in distribution networks taking into consideration the intermittent nature of wind generation. For this purpose a 61-bus radial distribution network has been modelled in Powerworld® simulator. Wind generation is connected at different locations of the network and these locations are identified as critical

I. S. Naser; A. Garba; O. Anaya-Lara; K. L. Lo

2009-01-01

13

Intrinsic Geometric Analysis of the Network Reliability and Voltage Stability  

E-print Network

This paper presents the intrinsic geometric model for the solution of power system planning and its operation. This problem is large-scale and nonlinear, in general. Thus, we have developed the intrinsic geometric model for the network reliability and voltage stability, and examined it for the IEEE 5 bus system. The robustness of the proposed model is illustrated by introducing variations of the network parameters. Exact analytical results show the accuracy as well as the efficiency of the proposed solution technique.

N. Gupta; B. N. Tiwari; S. Bellucci

2010-11-12

14

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

NASA Astrophysics Data System (ADS)

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.

Wu, Guohong; Minakawa, Tamotsu; Hayashi, Toshiyuki

15

Strategies for Voltage Control and Transient Stability Assessment  

SciTech Connect

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 betw

Hiskens, Ian A.

2013-09-25

16

Ultrasonic evaluation of high voltage circuit boards  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

17

Voltage stability and sensitivity analysis of grid-connected photovoltaic systems  

Microsoft Academic Search

Integration of significant amount of solar power challenges the power system stability operation. This paper presents analyses on the static and transient voltage characteristics at the point of common coupling of a grid-connected photovoltaic system. The static voltage response, known as a PV curve, for the photovoltaic system is analyzed. The voltage transient behaviors caused by the disturbance of parameters

Yaosuo Xue; Madhav Manjrekar; Chenxi Lin; Maria Tamayo; John N. Jiang

2011-01-01

18

Voltage Stability and Frequency Synchronization of Weak Power Distribution Networks with Inverter-Based  

E-print Network

Voltage Stability and Frequency Synchronization of Weak Power Distribution Networks with Inverter not apply to truly weak networks. Key words: Weak networks, inverter-based distributed generator, voltage and frequency stability. 1 INTRODUCTION Inverter-based distributed generation (DG) sources are usually a part

Lemmon, Michael

19

Josephson voltage standard as a current reference and practical method for stabilization of high current  

Microsoft Academic Search

A stable reference source with a high current capability is useful for many metrological applications. Unlike the conventional Josephson voltage standard, one can couple the programmable Josephson voltage standard (PJVS) to a current source below milliamp range to stabilize the current. For higher current ranges, we tested a feedback method which allowed us to stabilize the 0.1-A output current of

Kyu-Tae Kim; Mun-Seog Kim; Myungsoo Kim; Jürgen Niemeyer

2005-01-01

20

Voltage Stability Analysis of a Multiple-Infeed Load Center Using Phasor Measurement Data  

Microsoft Academic Search

Voltage stability is a security concern for modern power systems. It can be analyzed using detailed or equivalent models. In this paper a new approach is presented for voltage stability analysis using synchronized phasor measurement data. Simple equivalent models of the interconnected system and load side at a measurement point are estimated from the data, and then used for calculating

Mostafa Parniani; Joe H. Chow; Luigi Vanfretti; Bharat Bhargava; Armando Salazar

2006-01-01

21

An integrated approach for the voltage stability enhancement of large wind integrated power systems  

Microsoft Academic Search

This paper investigates the applicability of an integrated approach for the enhancement of voltage stability margin and there by the wind penetration of large wind integrated power systems. The proposed approach involves in two objectives; the identification of weak buses in the given power systems, enhancement of voltage stability margin of the weak buses and there by the wind penetration

B Maya; Sasidharan Sreedharan; Jai Govind Singh

2012-01-01

22

Preventive\\/Corrective Control for Voltage Stability Based on Primal-Dual Interior Point Method  

Microsoft Academic Search

The preventive\\/corrective control for voltage stability is an indispensable part of on-line voltage monitoring system. Hidden trouble of voltage stability could be eliminated by cooperation of preventive control and corrective control, thus the operating point could be in secure area continually. In this paper, a 168-bus real power system was investigated to illustrate how to solve optimal control problem using

Yue Yuan; Xuehong Wen; Kejun Qian

2006-01-01

23

Soft-switched three-level capacitor clamping inverter with clamping voltage stabilization  

Microsoft Academic Search

This paper proposes a zero-voltage-switching scheme for the three-level capacitor clamping inverter. The proposed small-rating auxiliary circuit ensures not only zero-voltage switching of the main switches and zero-current switching of the auxiliary switches, but the clamping capacitor voltage of the inverter is also stabilized. The scheme prevents any voltage or current spikes from happening over the main or auxiliary switches

Xiaoming Yuan; Ivo Barbi

2000-01-01

24

Stability analysis of nonlinear voltage inverter-induction motor system  

Microsoft Academic Search

The paper highlights the increased instability of the induction motor due to the nonlinearity introduced by the voltage inverter, nonlinearity produced by the dead time required for switching devices on the same phase. Voltage errors on phase and between phases against the load null are presented, as well as the fact that phase voltage error against load null is in

D. Stanciu; Adriana Florescu; D. A. Stoichescu

2008-01-01

25

Monitoring and control of voltage stability in power systems  

SciTech Connect

This paper proposes a new technique in controlling voltage instability in power systems. This technique coordinates between the reactive power of excitation systems and that of static var compensators (SVCs). The method starts with the decomposition of system into several voltage control areas (VCAs). When a reactive power deficiency occurs in certain area, excitation systems respond first to supply the required reactive power by increasing reactive generation of synchronous generators to its upper limit. If more reactive power is needed within the specific area to recover voltage instability, a SVC will be inserted by a switching controller in order to achieve the reactive balance. This controller receives an actuating signal when the terminal voltage is still unsatisfactory. By this technique, it is possible to fully utilize the excitation systems reactive power, and to design economic size SVCs to recover voltage instability. The application of the proposed technique on the New-England 39 bus system proves its efficiency in controlling voltage instability.

Sallam, A.A.; Aboul-Ela, M.E.; Elaraby, E.E. [Suez Canal Univ., Port-Said (Egypt)

1995-12-31

26

Discussion About the Corrective Control for Voltage Stability of Complex Power Systems Based on Primal-Dual Interior Point Method  

Microsoft Academic Search

As power systems become more complex and heavily loaded, voltage stability becomes an increasing serious problem. It is therefore necessary to develop an on-line voltage stability monitoring system in today's energy management systems (EMS). Voltage stability corrective control, one of the steps in the monitoring system, can be formulated as a static nonlinear optimization problem which can be solved by

Yue Yuan; Kejun Qian; Xuehong Wen

2006-01-01

27

Application of HSA and GA in optimal placement of FACTS devices considering voltage stability and losses  

Microsoft Academic Search

Voltage collapse is instability of heavily loaded electric power systems that cause to declining voltages and blackout. Power systems are predicated to become more heavily loaded in the future decade as the demand for electric power rises while economic and environmental concerns limit the construction of new transmission and generation capacity. Heavily loaded power systems are closer to their stability

A. Parizad; A. Khazali; M. Kalantar

2009-01-01

28

Optimal Location and Size of SVC and TCSC for Multi-objective Static Voltage Stability Enhancement  

Microsoft Academic Search

A Non-dominated Sorting Particle Swarm Optimization (NSPSO) is used to solve a mixed conti nuous- discreet Multi-objective optimization problem witch consist of optimal location and size of Static Var Compensators (SVC) and Thyristor Controlled Series Capacitors (TCSC) in order to maximize Static Voltage Stability Margi n (SVSM), reduce power losses (PL) and minimize load Voltage Deviations (VD). While finding the

R. Benabid; M. Boudour

29

Large-scale wind power integration and voltage stability limits in regional networks  

Microsoft Academic Search

When planning and developing large-scale wind power plants in areas distant from the main power transmission system, voltage control assessments and reactive power compensation are increasingly important. Voltage stability of the regional network may be a main limitation with respect to maximum rating and operation of the wind power plant Technical constraints in relation to wind power integration in weak

M. P. Palsson; T. Toftevaag; K. Uhlen; J. O. G. Tande

2002-01-01

30

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

PubMed

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

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

2015-02-01

31

Abstract--This paper reports a method to evaluate composite power system reliability indices incorporating the voltage  

E-print Network

3 Abstract--This paper reports a method to evaluate composite power system reliability indices into focus. Presently research is being carried to evolve methods and procedures to evaluate composite power incorporating the voltage stability margin criteria. To compute the load curtailment evaluation, an optimal

32

Under voltage load shedding for voltage stability overview of concepts and principles  

Microsoft Academic Search

Undervoltage load shedding (UVLS) has been employed in the electric utility industry as a 'safety net' measure to prevent or reduce the possibility of voltage collapse due to low-probability\\/high impact disturbances. This work provides an introduction to and provides an overview of the design and implementation considerations of a UVLS scheme. An overview of the power system equipment that impacts

Shamir S. Ladhani; William Rosehart

2004-01-01

33

ACCELERATING VOLTAGE AMPLITUDE AND PHASE STABILIZATION FOR THE MILAN SUPERCONDUCTING CYCLOTRON  

Microsoft Academic Search

Two feedback loops are employed to control the phase and the amplitude stability of the Milan Superconducting Cyclotron accelerating voltage. In this paper we describe the main features of these sys terns together with the experimental results obtained during the full power tests of the first RF cavity. In particular we obtained, all over the frequency range, a phase stability

A. Bosotti; A. Caruso; V. Lovati; C. Pagani; G. Varisco; F. Zihra; AMPLITUDE LOOP

34

Drain-bias dependence of threshold voltage stability of amorphous silicon TFTs  

Microsoft Academic Search

Amorphous silicon (a-Si:H) thin-film transistors (TFTs) used in emerging, nonswitch applications such as analog amplifiers or active loads, often have a bias at the drain terminal in addition to the gate that can alter their threshold voltage (VT) stability performance. At small gate stress voltages (0?VST?15 V) where the defect state creation instability mechanism is dominant, the presence of a

Karim S. Karim; Arokia Nathan; Michael Hack; William I. Milne

2004-01-01

35

Self-organized synchronization and voltage stability in networks of synchronous machines  

NASA Astrophysics Data System (ADS)

The integration of renewable energy sources in the course of the energy transition is accompanied by grid decentralization and fluctuating power feed-in characteristics. This development raises novel challenges for power system stability and design. We investigate power system stability from the viewpoint of self-organized synchronization aspects. In this approach, the power grid is represented by a network of synchronous machines. We supplement the classical Kuramoto-like network model, which assumes constant voltages, with dynamical voltage equations, and thus obtain an extended model, that incorporates the coupled categories voltage stability and rotor angle synchronization. We compare disturbance scenarios in small systems simulated on the basis of both classical and extended model and we discuss resultant implications and possible applications to complex modern power grids.

Schmietendorf, Katrin; Peinke, Joachim; Friedrich, Rudolf; Kamps, Oliver

2014-10-01

36

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

37

Voltage Stability Impact of Grid-Tied Photovoltaic Systems Utilizing Dynamic Reactive Power Control  

NASA Astrophysics Data System (ADS)

Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid, although this feature is currently rarely utilized as most DG systems are designed to operate with unity power factor and supply real power only to the grid. In this work, the voltage stability of a power system embedded with PV DG is examined in the context of the high reactive power requirement after a voltage sag or fault. A real-time dynamic multi-function power controller that enables renewable source PV DGs to provide the reactive power support necessary to maintain the voltage stability of the microgrid, and consequently, the wider power system is proposed. The loadability limit necessary to maintain the voltage stability of an interconnected microgrid is determined by using bifurcation analysis to test for the singularity of the network Jacobian and load differential equations with and without the contribution of the DG. The maximum and minimum real and reactive power support permissible from the DG is obtained from the loadability limit and used as the limiting factors in controlling the real and reactive power contribution from the PV source. The designed controller regulates the voltage output based on instantaneous power theory at the point-of-common coupling (PCC) while the reactive power supply is controlled by means of the power factor and reactive current droop method. The control method is implemented in a modified IEEE 13-bus test feeder system using PSCADRTM power system analysis software and is applied to the model of a Tampa ElectricRTM PV installation at Lowry Park Zoo in Tampa, FL. This dissertation accomplishes the systematic analysis of the voltage impact of a PV DG-embedded power distribution system. The method employed in this work bases the contribution of the PV resource on the voltage stability margins of the microgrid rather than the commonly used loss-of-load probability (LOLP) and effective load-carrying capability (ELCC) measures. The results of the proposed method show good improvement in the before-, during-, and post-start voltage levels at the motor terminals. The voltage stability margin approach provides the utility a more useful measure in sizing and locating PV resources to support the overall power system stability in an emerging smart grid.

Omole, Adedamola

38

Stability issues in IC Low Drop Out voltage regulators  

E-print Network

regulators, and improves transient response and noise performance. Test results from the prototype provide an evaluation of the most important parameters of the regulator: ground current, load regulation, line regulation, output noise and start-up time....

Chava, Krishna Chaitanya

2002-01-01

39

Decoupled power exchange model of UPFC to enhance voltage stability margin of power systems  

Microsoft Academic Search

This paper proposes a novel model of unified power flow controller (UPFC) for enhancing voltage stability margin of the power systems. This model is based upon an innovative approach where, real power exchange of series and shunt elements of UPFC are decoupled with each other. The UPFC model is incorporated into an existing Newton-Raphson load flow algorithm and Jacobian matrix

Rajive Tiwari; K. R. Niazi; Vikas Gupta

2011-01-01

40

MPC-Based Load Shedding for Voltage Stability Enhancement I.A. Hiskens B. Gong  

E-print Network

a finite horizon. Control decisions are based on optimizing that predicted response. MPC is a discrete-time in relieving system stress [2]. However counter-examples are easy to generate. The simple system of Fig. 1MPC-Based Load Shedding for Voltage Stability Enhancement I.A. Hiskens B. Gong Department

Hiskens, Ian A.

41

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

SciTech Connect

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.

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

2013-06-11

42

Auto-zero stabilized CMOS amplifiers for very low voltage or current offset Daniel Dzahini (1), Hamid Ghazlane (2)  

E-print Network

Auto-zero stabilized CMOS amplifiers for very low voltage or current offset Daniel Dzahini (1 Rabat Principal 10001 Morocco Abstract---In this paper, we present two amplifiers designed in CMOS precision operational amplifier focusing on the voltage offset. It is a continuous time auto-zero stabilized

Boyer, Edmond

43

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

44

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

SciTech Connect

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.

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

2012-11-23

45

All low voltage lateral junction scanning tunneling microscope with very high precision and stability  

NASA Astrophysics Data System (ADS)

We describe the first lateral junction and fully low voltage scanning tunneling microscope, featuring very high precision, stability, compactness, and image quality (highly oriented pyrolytic graphite atomic resolution images). In its core, the tip and sample each sit on one of two parallel-mounted piezoelectric tube scanners so that the tip-sample gap is regulated along the scanners' pairing direction. The scanner's large lateral deflection provides a large gap regulation range even under low voltages, allowing exclusively using only low voltage (less than ±15 V) operational amplifiers to precisely implement the coarse (inertial slider) and fine approach, feedback control, and hence the entire electronics. Because the scanners are identical and adjacent, thermal drifts are minimal.

Hou, Yubin; Wang, Jihui; Lu, Qingyou

2008-11-01

46

All low voltage lateral junction scanning tunneling microscope with very high precision and stability.  

PubMed

We describe the first lateral junction and fully low voltage scanning tunneling microscope, featuring very high precision, stability, compactness, and image quality (highly oriented pyrolytic graphite atomic resolution images). In its core, the tip and sample each sit on one of two parallel-mounted piezoelectric tube scanners so that the tip-sample gap is regulated along the scanners' pairing direction. The scanner's large lateral deflection provides a large gap regulation range even under low voltages, allowing exclusively using only low voltage (less than +/-15 V) operational amplifiers to precisely implement the coarse (inertial slider) and fine approach, feedback control, and hence the entire electronics. Because the scanners are identical and adjacent, thermal drifts are minimal. PMID:19045895

Hou, Yubin; Wang, Jihui; Lu, Qingyou

2008-11-01

47

The continuation power flow: a tool for steady state voltage stability analysis  

Microsoft Academic Search

The authors present a method of finding a continuum of power flow solutions starting at some base load and leading to the steady-state voltage stability limit (critical point) of the system. A salient feature of the so-called continuation power flow is that it remains well-conditioned at and around the critical point. As a consequence, divergence due to ill-conditioning is not

Venkataramana Ajjarapu; Colin Christy

1992-01-01

48

Optimal placement of FACTS devices for multi-objective voltage stability problem  

Microsoft Academic Search

In this paper, a new method for optimal locating multi-type FACTS devices in order to optimize multi-objective voltage stability problem is presented. The proposed methodology is based on a new variant of Particle Swarm Optimization (PSO) specialized in multi-objective optimization problem known as Non-dominated Sorting Particle Swarm Optimization (NSPSO). The crowding distance technique is used to maintain the Pareto front

R. Benabid; M. Boudour; M. A. Abido

2009-01-01

49

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

DOEpatents

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.

Taubman, Matthew S; Phillips, Mark C

2014-03-18

50

A corrective control for angle and voltage stability enhancement on the transient time-scale  

Microsoft Academic Search

This paper deals with the development of a nonlinear programming methodology for evaluating load shedding (LS) as a corrective action to improve the dynamic security of power systems when angle or voltage instability is detected. A centralized corrective control is developed, on the basis of online DSA computations, in order to ensure corrective actions when a threatening contingency actually occurs.

E. De Tuglie; M. Dicorato; M. La Scala; P. Scarpellini

2000-01-01

51

A corrective control for angle and voltage stability enhancement on the transient time-scale  

Microsoft Academic Search

Summary form only given as follows. This paper deals with the development of a nonlinear programming methodology for evaluating load shedding (LS) as a corrective action to improve the dynamic security of power systems when angle or voltage instability is detected. A centralized corrective control is armed, on the basis of on-line DSA computations, in order to ensure corrective actions

E. De Tuglie; M. Dicorato; M. La Scala; P. Scarpellini

2001-01-01

52

Voltage Stabilization in Microgrids via Quadratic Droop Control John W. Simpson-Porco, Florian Dorfler, and Francesco Bullo  

E-print Network

Voltage Stabilization in Microgrids via Quadratic Droop Control John W. Simpson-Porco, Florian D microgrid, we present a concise and closed-form condition for the existence of an exponentially stable high and social factors, and the rapidly expanding integration of low voltage small-scale renewable energy sources

Bullo, Francesco

53

Investigation of voltage and transient stability of HVAC network in hybrid with VSC-HVDC and HVDC Link  

Microsoft Academic Search

This paper reports on the stability of power systems using a weak two area HVAC link, in hybrid with HVDC and VSC-HVDC transmission schemes as case studies. The purpose of the study is to show the mitigating effect of the VSC-HVDC system on both voltage and transient stability in power systems, as compared to other transmission schemes. In the study,

L. C. Azimoh; K. Folly; S. P. Chowdhury; A. Haddad

2010-01-01

54

The simulation and evaluation of dynamic voltage scaling algorithms  

Microsoft Academic Search

The reduction of energy consumption in microprocessors can be accomplished without impacting the peak performance through the use of dynamic voltage scaling (DVS). This approach varies the processor voltage under software control to meet dynamically varying performance requirements. This paper presents a foundation for the simulation and analysis of DVS algorithms. These algorithms are applied to a benchmark suite specifically

Trevor Pering; Thomas D. Burd; Robert W. Brodersen

1998-01-01

55

Evaluation of Epoxy Nanocomposites for High Voltage Insulation  

NASA Astrophysics Data System (ADS)

Polymeric materials containing nanometer (nm) size particles are being introduced to provide compact shapes for low and medium voltage insulation equipment. The nanocomposites may provide superior electrical performance when compared with those available currently, such as lower dielectric losses and increased dielectric strength, tracking and erosion resistance, and surface hydrophobicity. All of the above mentioned benefits can be achieved at a lower filler concentration (< 10%) than conventional microfillers (40-60%). Also, the uniform shapes of nanofillers provide a better electrical stress distribution as compared to irregular shaped microcomposites which can have high internal electric stress, which could be a problem for devices with active electrical parts. Improvement in electrical performance due to addition of nanofillers in an epoxy matrix has been evaluated in this work. Scanning Electron Microscopy (SEM) was done on the epoxy samples to confirm uniform dispersion of nano-sized fillers as good filler dispersion is essential to realize the above stated benefits. Dielectric spectroscopy experiments were conducted over a wide range of frequencies as a function of temperature to understand the role of space charge and interfaces in these materials. The experiment results demonstrate significant reduction in dielectric losses in samples containing nanofillers. High voltage experiments such as corona resistance tests were conducted over 500 hours to monitor degradation in the samples due to corona. These tests revealed improvements in partial discharge endurance of nanocomposite samples. These improvements could not be adequately explained using a macroscopic quantity such as thermal conductivity. Thermo gravimetric analysis (TGA) showed higher weight loss initiation temperatures for nanofilled samples which is in agreement with the corona resistance experimental results. Theoretical models have also been developed in this work to complement the results of the corona resistance experiment and the TGA analysis. Degradation model was developed to map the erosion path using Dijkstra's shortest path algorithm. A thermal model was developed to calculate the localized temperature distribution in the micro and nano-filled samples using the PDE toolbox in MATLAB. Both the models highlight the fact that improvement in nanocomposites is not limited to the filler concentrations that were tested experimentally.

Iyer, Ganpathy

56

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

NASA Astrophysics Data System (ADS)

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).

Nguyen, Cuong Phuc

2011-12-01

57

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

SciTech Connect

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.

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

2012-01-01

58

Performance evaluation of high voltage super junction MOSFETs for zero-voltage soft-switching inverter applications  

Microsoft Academic Search

This paper evaluates three different 600V-level super junction (SJ) MOSFETs employed in zero-voltage soft-switching inverter applications. Inverter efficiency was measured and compared with the same inverter test setup by only changing different MOSFETs. Besides high efficiency requirement, better switching performance is also highly appreciated in various inverter applications. Comparison test was done on each super junction MOSFET to investigate its

Sung-Yeul Park; Pengwei Sun; Wensong Yu; Jih-Sheng Lai

2010-01-01

59

Evaluation of a high power ARCP voltage source inverter with IGCTs  

Microsoft Academic Search

An evaluation and comparison of a two-level conventional voltage source inverter (VSI) and an auxiliary resonant commutated pole voltage source inverter (ARCPVSI) featuring IGCTs for a 3 MVA application is presented. Design issues of both topologies are addressed. The IGCT loss approximations are based on extensive measurements of the devices under hard and soft switching conditions. The results show that

S. Bernet; R. Teichmann; J. Weber; P. K. Steimer

1999-01-01

60

Evaluation of induced stray voltages from transmission lines using EMTP  

Microsoft Academic Search

The purpose of this paper is to study the effect of transmission system parameters and operating conditions on generated stray voltage levels. This includes the transmission line conductor configurations, line loading levels, grounding system parameters, the feeder configuration (radial or ring configuration) and unbalance loading. This enables a better way to understand how different electrical parameters impact the level of

Nagy Abed; Sasan Salem; Jim Burke

2010-01-01

61

Effect of voltage current characteristic smoothness on the stability margin of cable-in-conduit conductors  

NASA Astrophysics Data System (ADS)

Experimental and numerical investigation of the AC losses induced by the transient magnet field (TMF) in cable-in-conduit conductors (CICC) revealed some interesting results. First of all, the critical current in the strands could be exceeded as a result of simultaneous increase of the strand temperature due to AC losses and the addition of the induced shielding currents to the transport current. Secondly, after the sample reaches its critical state the energy stored in the loops formed by the superconducting strands and normal "matrix" quickly dissipates in the normal matrix of the strands and in the normal "matrix" of the bundle. This results in a step increase of the conductor temperature. It was logical to assume that during the process preceding the occurrence of the first flux-jump, the maximum temperature and shielding current could depend on the smoothness of the voltage-current characteristic (VCC) of the superconducting strands. In other words, the smoothness of the VCC of the superconducting strands should influence the stability margin of a conductor. A numerical investigation of the VCC smoothness effect on stability margin was carried out for a wide range of the Stekly parameter, ?, and varying the dimensionless transport current i = It/ Ic (0 ? ? < 50; 0 ? i < 1). As a result of these calculations, it was found that the energy necessary for the first flux-jump to occur, grows as the VCC smoothness increases, when the Stekly parameter lies in the range 0 ? ? < 1, and the stability margin of a conductor decreases as the VCC smoothness increases, when the Stekly parameter ? ? 1.

Lelekhov, S. A.; Naumov, P. G.

2007-03-01

62

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

SciTech Connect

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.

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

2010-09-29

63

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

NASA Astrophysics Data System (ADS)

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.

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

64

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

65

Operational stability enhancement of low-voltage organic field-effect transistors based on bilayer polymer dielectrics  

NASA Astrophysics Data System (ADS)

Bilayer polymer dielectrics consisting of hydrophobic thin layers on high-k polyvinylalcohol (PVA) are utilized to realize p-type and n-type low-voltage organic field-effect transistors (OFETs), which show superior mobility and operational stability compared with the devices with PVA single-layer dielectric. The OFETs with top layers containing discrete ?-groups, such as polystyrene (PS) and poly(2-vinyl naphthalene) (PVN), show stronger bias stress instability than those with ?-group free polymethylmethacrylate (PMMA), and it is ascribed to slow charge trapping into the ?-groups under bias stress. By integrating p-type and n-type low-voltage OFETs based on PMMA/PVA bilayer dielectric, a low-power high-stability complementary inverter is achieved.

She, Xiao-Jian; Liu, Jie; Zhang, Jing-Yu; Gao, Xu; Wang, Sui-Dong

2013-09-01

66

Membrane bending is critical for the stability of voltage sensor segments in the membrane  

PubMed Central

The interaction between membrane proteins and the surrounding membrane is becoming increasingly appreciated for its role in regulating protein function, protein localization, and membrane morphology. In particular, recent studies have suggested that membrane deformation is needed to stably accommodate proteins harboring charged amino acids in their transmembrane (TM) region, as it is energetically prohibitive to bury charge in the hydrophobic core of the bilayer. Unfortunately, current computational methods are poorly equipped for describing such deformations, as atomistic simulations are often too short to observe large-scale membrane reorganization and most continuum approaches assume a flat membrane. Previously, we developed a method that overcomes these shortcomings by using elasticity theory to characterize equilibrium membrane distortions in the presence of a TM protein, while using traditional continuum electrostatic and nonpolar energy models to determine the energy of the protein in the membrane. Here, we linked the elastostatics, electrostatics, and nonpolar numeric solvers to permit the calculation of energies for nontrivial membrane deformations. We then coupled this procedure to a robust search algorithm that identifies optimal membrane shapes for a TM protein of arbitrary chemical composition. This advance now permits us to explore a host of biological phenomena that were beyond the scope of our original method. We show that the energy required to embed charged residues in the membrane can be highly nonadditive, and our model provides a simple mechanical explanation for this nonadditivity. Our results also predict that isolated voltage sensor segments do not insert into rigid membranes, but membrane bending dramatically stabilizes these proteins in the bilayer despite their high charge content. Additionally, we use the model to explore hydrophobic mismatch with regard to nonpolar peptides and mechanosensitive channels. Our method is in quantitative agreement with molecular dynamics simulations at a tiny fraction of the computational cost. PMID:22732310

Callenberg, Keith M.; Latorraca, Naomi R.

2012-01-01

67

Evaluation of high-voltage, high-power, solid-state remote power controllers for amps  

NASA Astrophysics Data System (ADS)

The Electrical Power Branch at Marshall Space Flight Center has a Power System Development Facility where various power circuit breadboards are tested and evaluated. This project relates to the evaluation of a particular remote power controller (RPC) energizing high power loads. The Facility equipment permits the thorough testing and evaluation of high-voltage, high-power solid-state remote power controllers. The purpose is to evaluate a Type E, 30 Ampere, 200 V dc remote power controller. Three phases of the RPC evaluation are presented. The RPC is evaluated within a low-voltage, low-power circuit to check its operational capability. The RPC is then evaluated while performing switch/circuit breaker functions within a 200 V dc, 30 Ampere power circuit. The final effort of the project relates to the recommended procedures for installing these RPC's into the existing Autonomously Managed Power System (AMPS) breadboard/test facility at MSFC.

Callis, Charles P.

1987-11-01

68

Evaluation of high-voltage, high-power, solid-state remote power controllers for amps  

NASA Technical Reports Server (NTRS)

The Electrical Power Branch at Marshall Space Flight Center has a Power System Development Facility where various power circuit breadboards are tested and evaluated. This project relates to the evaluation of a particular remote power controller (RPC) energizing high power loads. The Facility equipment permits the thorough testing and evaluation of high-voltage, high-power solid-state remote power controllers. The purpose is to evaluate a Type E, 30 Ampere, 200 V dc remote power controller. Three phases of the RPC evaluation are presented. The RPC is evaluated within a low-voltage, low-power circuit to check its operational capability. The RPC is then evaluated while performing switch/circuit breaker functions within a 200 V dc, 30 Ampere power circuit. The final effort of the project relates to the recommended procedures for installing these RPC's into the existing Autonomously Managed Power System (AMPS) breadboard/test facility at MSFC.

Callis, Charles P.

1987-01-01

69

A linearly tunable low-voltage CMOS transconductor with improved common-mode stability and its application to gmC filters  

Microsoft Academic Search

A linearly tunable low-voltage CMOS transconductor featuring a new adaptive-bias mechanism that considerably improves the stability of the processed-signal common-mode voltage over the tuning range, critical for very-low voltage applications, is introduced. It embeds a feedback loop that holds input devices on triode region while boosting the output resistance. Analysis of the integrator frequency response gives an insight into the

Jader A. De Lima; Carlos Dualibe

2001-01-01

70

Anticonvulsants as mood stabilizers and adjuncts to antipsychotics: valproate, lamotrigine, carbamazepine, and oxcarbazepine and actions at voltage-gated sodium channels.  

PubMed

Actions of certain anticonvulsants upon voltage-gated sodium channels may not only explain why they are effective mood stabilizers but may also explain why they could be useful adjuncts to antipsychotics for resistant psychosis. PMID:15291647

Stahl, Stephen M

2004-06-01

71

Voltage Stability Analysis With Optimum Size and Location Based Synchronous Machine DG  

E-print Network

higher than the emission from other sectors like industrial processes and agriculture [3]. As a result barrier is voltage rise issue. Inappropriate size and allocation of DG can cause low or overvoltage

Pota, Himanshu Roy

72

Stability evaluation of tramadol enantiomers using a chiral stability-indicating capillary electrophoresis method and its application to pharmaceutical analysis.  

PubMed

In this study, a chiral stability-indicating CE assay was developed for the stability evaluation of tramadol (TR) enantiomers in commercial tablets using maltodextrin as chiral selector. To investigate the stability-indicating power of the analytical method as well as stability evaluation of TR enantiomers, active pharmaceutical ingredient and TR tablets were subjected to photolysis, heat, oxidation and hydrolysis to conduct stress testing. Best separation for the TR enantiomers was achieved on an uncoated fused-silica capillary at 20 °C using borate buffer (50 mM, pH 10.2) containing 10% m/v maltodextrin. All determinations were performed by a UV detector at 214 nm. A constant voltage of 20 kV was applied to obtain the separation. The range of quantitation for both enantiomers was 5-100 ?g/mL (R>0.996). Intra- and inter-day RSD (n=6) were less than 10%. The percent relevant errors were obtained to be less than 4.0 for both enantiomers. The limits of quantitation and detection for both enantiomers were 5 and 1.5 ?g/mL, respectively. Degradation products resulting from the stress studies were the same for both enantiomers and did not interfere with the detection of the enantiomers. PMID:21626694

Mohammadi, Ali; Nojavan, Saeed; Rouini, Mohammadreza; Fakhari, Ali Reza

2011-07-01

73

Technical evaluation of the adequacy of station electric distribution system voltages for the Yankee Rowe Nuclear Power Station  

Microsoft Academic Search

This report documents the technical evaluation of the adequacy of the station electric distribution system voltages for the Yankee Rowe Nuclear Power Station. 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

Selan

1981-01-01

74

Technical evaluation of the adequacy of station electric distribution system voltages for the San Onofre Nuclear Generating Station, Unit 1  

Microsoft Academic Search

This report documents the technical evaluation of the adequacy of the station electric distribution system voltages for the San Onofre Nuclear Generating Station, Unit. 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

Selan

1982-01-01

75

Voltage Stability and Power Quality Issues of Wind Farm with Series Compensation  

E-print Network

generator (DFIG) wind farms with series and shunt compensation are analyzed. The voltage source converter of a static synchronous compensator (STATCOM), the converter side of a DFIG and a load are considered-speed wind turbine (FSWT) and doubly-fed induction generator (DFIG) based wind farms. The expected number

Pota, Himanshu Roy

76

Nonlinear DSTATCOM controller design for distribution network with distributed generation to enhance voltage stability  

E-print Network

­3]. The impact of integrating a single or small amount of distributed generation may not be a significant issue of low or medium voltage distribution networks [4­7]. The control of reactive power generation plays to the distribution network as DG, it is essential to provide some reactive power to the system to maintain

Pota, Himanshu Roy

77

Determinants of Voltage-Dependent Gating and Open-State Stability in the S5 Segment of Shaker Potassium Channels  

PubMed Central

The best-known Shaker allele of Drosophila with a novel gating phenotype, Sh5, differs from the wild-type potassium channel by a point mutation in the fifth membrane-spanning segment (S5) (Gautam, M., and M.A. Tanouye. 1990. Neuron. 5:67–73; Lichtinghagen, R., M. Stocker, R. Wittka, G. Boheim, W. Stühmer, A. Ferrus, and O. Pongs. 1990. EMBO [Eur. Mol. Biol. Organ.] J. 9:4399–4407) and causes a decrease in the apparent voltage dependence of opening. A kinetic study of Sh5 revealed that changes in the deactivation rate could account for the altered gating behavior (Zagotta, W.N., and R.W. Aldrich. 1990. J. Neurosci. 10:1799–1810), but the presence of intact fast inactivation precluded observation of the closing kinetics and steady state activation. We studied the Sh5 mutation (F401I) in ShB channels in which fast N-type inactivation was removed, directly confirming this conclusion. Replacement of other phenylalanines in S5 did not result in substantial alterations in voltage-dependent gating. At position 401, valine and alanine substitutions, like F401I, produce currents with decreased apparent voltage dependence of the open probability and of the deactivation rates, as well as accelerated kinetics of opening and closing. A leucine residue is the exception among aliphatic mutants, with the F401L channels having a steep voltage dependence of opening and slow closing kinetics. The analysis of sigmoidal delay in channel opening, and of gating current kinetics, indicates that wild-type and F401L mutant channels possess a form of cooperativity in the gating mechanism that the F401A channels lack. The wild-type and F401L channels' entering the open state gives rise to slow decay of the OFF gating current. In F401A, rapid gating charge return persists after channels open, confirming that this mutation disrupts stabilization of the open state. We present a kinetic model that can account for these properties by postulating that the four subunits independently undergo two sequential voltage-sensitive transitions each, followed by a final concerted opening step. These channels differ primarily in the final concerted transition, which is biased in favor of the open state in F401L and the wild type, and in the opposite direction in F401A. These results are consistent with an activation scheme whereby bulky aromatic or aliphatic side chains at position 401 in S5 cooperatively stabilize the open state, possibly by interacting with residues in other helices. PMID:10435999

Kanevsky, Max; Aldrich, Richard W.

1999-01-01

78

A novel mechanism for fine-tuning open-state stability in a voltage-gated potassium channel  

PubMed Central

Voltage-gated potassium channels elicit membrane hyperpolarization through voltage-sensor domains that regulate the conductive status of the pore domain. To better understand the inherent basis for the open-closed equilibrium in these channels, we undertook an atomistic scan using synthetic fluorinated derivatives of aromatic residues previously implicated in the gating of Shaker potassium channels. Here we show that stepwise dispersion of the negative electrostatic surface potential of only one site, Phe481, stabilizes the channel open state. Furthermore, these data suggest that this apparent stabilization is the consequence of the amelioration of an inherently repulsive open-state interaction between the partial negative charge on the face of Phe481 and a highly co-evolved acidic side chain, Glu395, and this interaction is potentially modulated through the Tyr485 hydroxyl. We propose that the intrinsic open-state destabilization via aromatic repulsion represents a new mechanism by which ion channels, and likely other proteins, fine-tune conformational equilibria. PMID:23653196

Pless, Stephan A.; Niciforovic, Ana P.; Galpin, Jason D.; Nunez, John-Jose; Kurata, Harley T.; Ahern, Christopher A.

2013-01-01

79

Annual stability evaluation of Waste Isolation Pilot Plant  

SciTech Connect

A stability evaluation of the underground workings of the Waste Isolation Pilot Plant (WIPP) was completed by the US Bureau of Mines` WIPP evaluation committee. This work included a critical evaluation of the processes employed at WIPP to ensure stability, an extensive review of available deformation measurements, a 3-day site visit, and interviews with the Department of Energy (DOE) and Westinghouse staff. General ground control processes are in place at WIPP to minimize the likelihood that major stability problems will go undetected. To increase confidence in both short- and long-term stability throughout the site (underground openings and shafts), ground stability monitoring systems, mine layout design, support systems and data analyses must be continuously improved. Such processes appear to be in place at WIPP and are discussed in this paper.

Not Available

1993-06-01

80

Design and evaluation of a preprototype hybrid fiber-optic voltage sensor for a remotely interrogated condition monitoring system  

Microsoft Academic Search

In this paper, we give details of the design and laboratory evaluation of the preprototype hybrid fiber Bragg grating piezoelectric voltage sensor for a remotely interrogated condition monitoring system, such as the measurement system used for monitoring of electrical submersible pump (ESP) motors. The proposed sensor design is directed toward the upper voltage rating (5 kV) of ESP motors.

Pawel Niewczas; Lukasz Dziuda; Grzegorz Fusiek; James R. McDonald

2005-01-01

81

Application of artificial neural network methods for the lightning performance evaluation of Hellenic high voltage transmission lines  

Microsoft Academic Search

Feed-forward (FF) artificial neural networks (ANN) and radial basis function (RBF) ANN methods were addressed for evaluating the lightning performance of high voltage transmission lines. Several structures, learning algorithms and transfer functions were tested in order to produce a model with the best generalizing ability. Actual input and output data, collected from operating Hellenic high voltage transmission lines, as well

L. Ekonomou; I. F. Gonos; D. P. Iracleous; I. A. Stathopulos

2007-01-01

82

STABILIZER: Statistically Sound Performance Evaluation Charlie Curtsinger Emery D. Berger  

E-print Network

STABILIZER: Statistically Sound Performance Evaluation Charlie Curtsinger Emery D. Berger Dept for sound performance evaluation on modern architectures. STA- BILIZER forces executions to sample the space. Introduction The task of performance evaluation forms a key part of both systems research and the software

Berger, Emery

83

Voltage Stability of Weak Power Distribution Networks with Inverter Connected Sources  

E-print Network

and provides a path for greater use of renewable energy resources. Microgrids can also be operated, Meng Xia1, and Michael Lemmon1 Abstract-- Microgrids are power distribution systems in which generation stability becomes a significant issue in microgrids when the network interconnections are weak. This paper

Lemmon, Michael

84

Regulation of high-voltage-activated Ca2+ channel function, trafficking, and membrane stability by auxiliary subunits  

PubMed Central

Voltage-gated Ca2+ (CaV) channels mediate Ca2+ ions influx into cells in response to depolarization of the plasma membrane. They are responsible for initiation of excitation-contraction and excitation-secretion coupling, and the Ca2+ that enters cells through this pathway is also important in the regulation of protein phosphorylation, gene transcription, and many other intracellular events. Initial electrophysiological studies divided CaV channels into low-voltage-activated (LVA) and high-voltage-activated (HVA) channels. The HVA CaV channels were further subdivided into L, N, P/Q, and R-types which are oligomeric protein complexes composed of an ion-conducting CaV?1 subunit and auxiliary CaV?2?, CaV?, and CaV? subunits. The functional consequences of the auxiliary subunits include altered functional and pharmacological properties of the channels as well as increased current densities. The latter observation suggests an important role of the auxiliary subunits in membrane trafficking of the CaV?1 subunit. This includes the mechanisms by which CaV channels are targeted to the plasma membrane and to appropriate regions within a given cell. Likewise, the auxiliary subunits seem to participate in the mechanisms that remove CaV channels from the plasma membrane for recycling and/or degradation. Diverse studies have provided important clues to the molecular mechanisms involved in the regulation of CaV channels by the auxiliary subunits, and the roles that these proteins could possibly play in channel targeting and membrane Stabilization. PMID:24949251

Felix, Ricardo; Calderón-Rivera, Aida; Andrade, Arturo

2014-01-01

85

Organic-silicon heterojunction solar cells: Open-circuit voltage potential and stability  

NASA Astrophysics Data System (ADS)

We characterize the electronic properties of crystalline silicon (c-Si)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) junctions by means of contactless carrier lifetime measurements. The measurements demonstrate that this type of heterojunction has an unexpectedly high open-circuit voltage (Voc) potential exceeding 690 mV, making it relevant for the implementation into high-efficiency c-Si solar cells. Hybrid n-type c-Si solar cells featuring a PEDOT:PSS hole-transport layer on the front reach an energy conversion efficiency of 12.3%. We observe a humidity-related degradation in cell efficiency during storage in air. The degradation is reduced by capping the entire device by an atomic-layer-deposited aluminum oxide film and is completely avoided in a dehumidified environment.

Schmidt, Jan; Titova, Valeriya; Zielke, Dimitri

2013-10-01

86

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

NASA Astrophysics Data System (ADS)

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.

Burkholder, Michael B.; Litster, Shawn

2015-02-01

87

Evaluation of the Threshold of Stability for the Human Spine  

PubMed Central

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

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

2009-01-01

88

ENVIRONMENTAL EVALUATION FOR UTILIZATION OF ASH IN SOIL STABILIZATION  

SciTech Connect

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.

David J. Hassett; Loreal V. Heebink

2001-08-01

89

On the Effect of Non-Carbon Nanostructured Supports on the Stability of Pt Nanoparticles during Voltage Cycling: a Study of TiO2 Nanofibres  

E-print Network

1 On the Effect of Non-Carbon Nanostructured Supports on the Stability of Pt Nanoparticles during Voltage Cycling: a Study of TiO2 Nanofibres I. Savych, J. Bernard d'Arbigny, S. Subianto, S. Cavaliere-mail: sara.cavaliere@univ-montp2.fr Abstract Electrospun carbon and Nb-doped TiO2 nanofibres (CNFs, TNFs

Boyer, Edmond

90

Fast response wavelength tunable filter using Vertically-Aligned Polymer-Stabilized Liquid Crystals (VA-PSLC) with a curing voltage  

NASA Astrophysics Data System (ADS)

We present preliminary experimental results obtained for a Vertically-Aligned Polymer Stabilized Liquid Crystal (VA-PSLC) with a curing voltage. The curing voltage was found to help reduce the otherwise strong scattering effect of the VA-PSLC. This liquid crystal was placed inside a Fabry-Perot cavity to achieve a wavelength tunable filter. Wavelength tuning range was found to decrease as curing voltage increased, which is consistent with what we expected since molecules were already tilted at a large angle when the curing voltage was high. Shortening of response time was found since the polymer effect helped improve the response speed. The filters can have potential applications in wavelength tuning applications (e.g. WDM) in telecommunication systems where high speed is desirable.

Choi, Wing-Kit; Li, Yan-Min

2014-10-01

91

Evaluation of oxidative stability of canola oils by headspace analysis  

Microsoft Academic Search

Lipid oxidation is a major factor affecting flavor quality and shelf life of vegetable oils. Oxidative stability is therefore\\u000a an important criterion by which oils are judged for usefulness in various food applications. In this study a method based\\u000a on headspace analysis was developed to evaluate relative oxidative stability of canola oils. The method does not require the\\u000a use of

Amy Richards; Chakra Wijesundera; Phil Salisbury

2005-01-01

92

Evaluation of Silicone Rubber Insulators used in High-Voltage Transmission Lines  

NASA Astrophysics Data System (ADS)

Three long-rod silicone rubber composite insulators used in 230 kV power transmission lines were evaluated for aging affects. The insulators were obtained from various outdoor desert locations within Saudi Arabia where they had been in service for 6 years. Surface degradation associated with the aging process was analyzed by using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infra-Red Spectroscopy (FTIR), and Electron Spectroscopy for Chemical Analysis (ESCA). Electrical performance of insulators was evaluated by Rapid Flashover Voltage Tests (RFVT) and Pollution Severity Measurement Tests. Depending on their locations of service, the samples exhibited various types of pollutants at their surfaces. The analysis indicated that the insulator material showed localized surface degradation while there was no evidence of micro-cracking. Furthermore, it was noted that the electrical performance of the insulators was not significantly affected by exposure during the in-service period.

Ul-Hamid, Anwar; Soufi, Khaled Y.; Al-Hamoudi, Ibrahim

2008-04-01

93

Abandoned metal mine stability risk evaluation.  

PubMed

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

Bétournay, Marc C

2009-10-01

94

Characterisation and stability evaluation of bixin nanocapsules.  

PubMed

The aim of this study was to produce bixin nanocapsules by the interfacial deposition of preformed poly-?-caprolactone (PCL). PCL (250 mg), capric/caprylic triglyceride (400 ?L), sorbitan monostearate (95 mg) and bixin were dissolved in a mixture of acetone (60 mL) and ethanol (7.5 mL) under stirring (40 °C). This organic solution was added to the aqueous solution (130 mL) containing Tween 80 (195 mg). The size distributions in the formulations with bixin concentration from 11 to 100 ?g/mL were evaluated periodically during 3 weeks of storage at ambient temperature. The optimal formulation (bixin concentration of 16.92±0.16 ?g/mL) was characterised in terms of particle size distribution, zeta potential, bixin content and encapsulation efficiency, and showed a volume-weighted mean diameter (D4,3) of 195±27 nm, around 100% of encapsulation efficiency and the nanocapsules were considered physically stable during 119 days of storage at ambient temperature. PMID:23993564

Lobato, Kleidson Brito de Sousa; Paese, Karina; Forgearini, Joana Casanova; Guterres, Silvia Stanisçuaski; Jablonski, André; Rios, Alessandro de Oliveira

2013-12-15

95

Oxidative stability and sensory evaluation of microencapsulated flaxseed oil.  

PubMed

Cold pressed flaxseed oil was microencapsulated by spray drying using an emulsion containing modified starch. The fatty acid composition, moisture, water activity, wettability, water holding capacity, water solubility, crystallinity, and particle size distribution of the microcapsules were determined. The stability of the microcapsules and the crude oil were assessed. An acceptance test was used for the sensory evaluation of a powdered supplement containing the microcapsules. The fatty acid composition was not significantly affected by the microencapsulation. The moisture, water activity, wettability, water solubility and crystallinity were appropriate for dry powders. The microcapsules had no cracks and showed better oxidative stability compared with the crude oil. Storage under vacuum prevented oxidation of the microcapsules. In sensory evaluation, all quality scores of the supplement containing microcapsules were mid-range or higher. The microencapsulation improved the oxidative stability of the oil and this procedure was satisfactorily applied in powdered food. PMID:23962202

Barroso, Ana Karina Mauro; Pierucci, Anna Paola Trindade Rocha; Freitas, Suely Pereira; Torres, Alexandre Guedes; Rocha-Leão, Maria Helena Miguez da

2014-01-01

96

Stability evaluation of the Markel Mine at Weeks Island, Louisiana  

SciTech Connect

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.

Hoffman, E.L.

1994-06-01

97

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

SciTech Connect

This work reports the surface stability of the high voltage Li ion cathode LiMn{sub 2–x}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.

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

2012-01-01

98

High air stability of threshold voltage on gate bias stress in pentacene TFTs with a hydroxyl-free and amorphous fluoropolymer as gate insulators  

Microsoft Academic Search

We investigated the air stabilities of threshold voltages (Vth) on gate bias stress in pentacene thin-film transistors (TFTs) with a hydroxyl-free and amorphous fluoropolymer as gate insulators. The 40-nm-thick thin films of spin-coated fluoropolymer had excellent electrical insulating properties, and the pentacene TFTs exhibited negligible current hysteresis, low leakage current, a field-effect mobility of 0.45cm2\\/Vs and an on\\/off current ratio

Tokiyoshi Umeda; Daisuke Kumaki; Shizuo Tokito

2008-01-01

99

Process and User Driven Dynamic Voltage and Frequency Scaling  

Microsoft Academic Search

We propose and evaluate two new and independently-applicable techniques, process- driven voltage scaling (PDVS) and user-driven frequency scaling (UDFS), for improved power management on processors that support Dynamic Voltage and Frequency Scaling (DVFS), e.g, those used in current laptop and desktop computers. In PDVS, a CPU- customized profile is derived offline that encodes the minimum voltage needed to achieve stability

Arindam Mallik; Bin Lin; Peter Dinda; Gokhan Memik; Robert Dick

100

[Quality evaluation and stability investigation of asarone submicro emulsion injection].  

PubMed

The content of the asarone submicro emulsion injection was determind by HPLC method, and thereby a quality evaluation method was established based on indexes of pH value, particle size, peroxide value, methoxy aniline values, free fatty acid, lysophosphatidylcholine, visible foreign substances, insoluble particle, sterility, bacterial endotoxin and impurities, etc. The results showed that the injection exhibited uniform physical appearance and all the products were in milkwhite liquid. The content of the three batches products were respectively 102.9%, 100.8%, 97.70% of the labeled amount, with mean particle size of 210-250 nm, and other indexes all met with the standards. The reserved samples showed no obvious change in terms of detection indexes and indicated good stability after the accelerated stability test and long-term stability for 12 months. The quality evaluation method established in this study could be applied to quality control and stability investigation of asarone submicron emulsion injection, which laid a basis for further clinical research and application. PMID:25751943

Li, Hong-Jia; Lai, Xiu-Jun; Li, Wei; Chu, Ting; Jin, Hui; Mao, Sheng-Jun

2014-10-01

101

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

ERIC Educational Resources Information Center

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

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

2010-01-01

102

Evaluation of the input current quality by three different modulation strategies for SVM controlled matrix converters with input voltage unbalance  

Microsoft Academic Search

A new input current modulation strategy for a matrix power converter is presented. The performance of the new strategy during input voltage unbalance is compared to two other strategies. The difference of the three modulations only concerns the detection of the reference angle for the input current vector. The input current quality is evaluated using four different criteria. It is

Peter Nielsen; Domenico Casadei; Giovanni Serra; Angelo Tani

1996-01-01

103

Technical-evaluation report on the adequacy of station electric-distribution-system voltages for the San Onofre Nuclear Generating Station, Unit 1. Document No. 50-206  

Microsoft Academic Search

This report documents the technical evaluation of the adequacy of the station electric distribution system voltages for the San Onofre Nuclear Generating Station, Unit 1. 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

Selan

1982-01-01

104

Rapid evaluation of a protein-based voltage probe using a field-induced membrane potential change.  

PubMed

The development of a high performance protein probe for the measurement of membrane potential will allow elucidation of spatiotemporal regulation of electrical signals within a network of excitable cells. Engineering such a probe requires a functional screen of many candidates. Although the glass-microelectrode technique generally provides an accurate measure of a given test probe, throughputs are limited. In this study, we focused on an approach that uses the membrane potential changes induced by an external electric field in a geometrically simple mammalian cell. For quantitative evaluation of membrane voltage probes that rely on the structural transition of the S1-S4 voltage sensor domain and hence have non-linear voltage dependencies, it was crucial to introduce exogenous inwardly rectifying potassium conductance to reduce cell-to-cell variability in resting membrane potentials. Importantly, the addition of the exogenous conductance drastically altered the profile of the field-induced potential. Following a site-directed random mutagenesis and the rapid screen, we identified a mutant of a voltage probe Mermaid, exhibiting positively shifted voltage sensitivity. Due to its simplicity, the current approach will be applicable under a microfluidic configuration to carry out an efficient screen. Additionally, we demonstrate another interesting aspect of the field-induced optical signals, ability to visualize electrical couplings between cells. PMID:24642225

Tsutsui, Hidekazu; Jinno, Yuka; Tomita, Akiko; Okamura, Yasushi

2014-07-01

105

A novel neutral point potential stabilization technique using the information of output current polarities and voltage vector  

Microsoft Academic Search

This paper proposes a new neutral point potential control technique for the neutral-point-clamped three-level inverter. Utilizing the phase current polarity information, this technique distributes the redundant voltage vectors in a manner to obtain stable neutral point voltage under all operating conditions including the zero-power-factor condition. Detailed analysis and computer simulations show the superiority of the proposed method. The feasibility of

Katsutoshi Yamanaka; Ahmet M. Hava; Hiroshi Kirino; Yoshiyuki Tanaka; Noritaka Koga; Tsuneo Kume

2002-01-01

106

An Evaluation of Two-Level and Three-Level Zero-Voltage Zero-Current Switching Converters  

Microsoft Academic Search

This paper presents a comparative evaluation of the two-level full-bridge zero-voltage zero-current switching (ZVZCS) converter and the three-level half-bridge ZVZCS converter. The paper analyzes the operation and soft-switching limits of both converters, compares them from a theoretical point of view, and presents an approach to optimize their designs. Experimental results are presented to illustrate the performance of both converters..

A. Medury; J. Carr; C. Balda; H. A. Mantooth

2007-01-01

107

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

SciTech Connect

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.

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

2011-01-01

108

FACTS technology application to retire aging transmission assets and address voltage stability related reliability challenges in San Francisco bay area  

Microsoft Academic Search

Loadability of electric transmission system in North America is currently influenced and restricted by several technical considerations. Since highly loaded transmission systems (with, consequently, high reactive power losses) are at the root of many reactive deficiency problems, it is not surprising that voltage instability\\/collapse are cause for increasing concern among transmission planners and operators. Detailed technical studies routinely performed by

Bhaskar Ray

2003-01-01

109

Facts technology application to retire aging transmission assets and address voltage stability related reliability challenges in San Francisco Bay Area  

Microsoft Academic Search

Loadability of electric transmission system in North America is currently influenced and restricted by several technical considerations. Since highly loaded transmission systems (with, consequently, high reactive power losses) are at the root of many reactive deficiency problems, it is not surprising that voltage instabilitykollapse are cause for increasing concern among transmission planners and operators. Detailed technical studies routinely performed by

Bhaskar Ray

2003-01-01

110

Optical voltage reference  

DOEpatents

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.

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

1994-01-01

111

Optical voltage reference  

DOEpatents

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.

Rankin, R.; Kotter, D.

1994-04-26

112

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

SciTech Connect

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.

Hazelrigg, Jr, George A.

1981-01-01

113

Design and evaluation of a pre-prototype hybrid fiber-optic voltage sensor for a remotely interrogated condition monitoring system  

Microsoft Academic Search

In this paper we give details of the design and laboratory evaluation of the pre-prototype hybrid fiber Bragg grating piezoelectric voltage sensor for a remotely interrogated condition monitoring system, such as the measurement system used for monitoring of electrical submersible pump (ESP) motors. The proposed sensor design is directed towards the upper voltage rating (5 kV) of ESP motors.

P. Niewczas; L. Dzitida; G. Fusiek; J. R. McDonald

2004-01-01

114

Asymmetric synthesis and evaluation of a hydroxyphenylamide voltage-gated sodium channel blocker in human prostate cancer xenografts  

PubMed Central

Voltage-gated sodium channels are known to be expressed in neurons and other excitable cells. Recently, voltage-gated sodium channels have been found to be expressed in human prostate cancer cells. ?-Hydroxy-?-phenylamides are a new class of small molecules that have demonstrated potent inhibition of voltage-gated sodium channels. The hydroxyamide motif, an isostere of a hydantoin ring, provides an active scaffold from which several potent racemic sodium channel blockers have been derived. With little known about chiral preferences, the development of chiral syntheses to obtain each pure enantiomer for evaluation as sodium channel blockers is important. Using Seebach and Frater's chiral template, cyclocondensation of (R)-3-chloromandelic acid with pivaldehyde furnished both the cis- and trans-2,5-disubsituted dioxolanones. Using this chiral template, we synthesized both enantiomers of 2-(3-chlorophenyl)-2-hydroxynonanamide, and evaluated their ability to functionally inhibit hNav isoforms, human prostate cancer cells and xenograft. Enantiomers of lead demonstrated significant ability to reduce prostate cancer in vivo. PMID:22364743

Davis, Gary C.; Kong, Yali; Paige, Mikell; Li, Zhang; Merrick, Ellen C.; Hansen, Todd; Suy, Simeng; Wang, Kan; Dakshanamurthy, Sivanesan; Cordova, Antoinette; McManus, Owen B.; Williams, Brande S.; Chruszcz, Maksymilian; Minor, Wladek; Patel, Manoj K.; Brown, Milton L.

2013-01-01

115

Analysis and Performance Evaluation of Triac-Voltage Controlled Capacitor Run Induction Motor  

Microsoft Academic Search

This article presents steady-state analysis and simulation of triac-voltage controlled capacitor run single-phase induction motor driving a domestic fan load. Two schemes of circuits, namely, line controlled and branch controlled configurations, suitable for speed control are considered and simulation results are presented. Also, the two schemes are compared in terms of motor efficiency, line current pollution, and input power factor,

K. SUNDARESWARAN; P. S. MANUJITH

2004-01-01

116

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

117

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

NASA Astrophysics Data System (ADS)

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, Iexcess = Ir0 + K1 exp (K2 V), where Ir0, K1, and K2 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.

Gopal, Vishnu; Qiu, WeiCheng; Hu, Weida

2014-11-01

118

Demonstration and Field Evaluation of Streambank Stabilization with Submerged Vanes  

USGS Publications Warehouse

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.

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

2001-01-01

119

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

SciTech Connect

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.

Not Available

1981-04-01

120

Evaluation of the input current quality by three different modulation strategies for SVM controlled matrix converters with input voltage unbalance  

SciTech Connect

A new input current modulation strategy for a matrix converter is presented. The performance of the new strategy during input voltage unbalance is compared to two other strategies. The difference of the three modulations only concerns the detection of the reference angle for the input current vector. The input current quality is evaluated using four different criteria. It is concluded that depending upon the modulation strategy, the distortion of the input current may appear either as a series of positive sequence harmonics or a negative sequence fundamental component or a positive and a negative series of harmonic components with reduced amplitudes. Good accordance is found between the analytical solutions and numerical simulation.

Nielsen, P. [Danfoss A/S, Graasten (Denmark). Transmission Div.; Casadei, D.; Serra, G.; Tani, A. [Univ. degli Studi di Bologna (Italy). Ist. di Elettrotecnica

1995-12-31

121

Global Stability of Banking Networks Against Financial Contagion: Measures, Evaluations and  

E-print Network

Global Stability of Banking Networks Against Financial Contagion: Measures, EvaluationsGupta (UIC) Global Stability of Banking Networks September 16, 2014 2 / 48 #12;Introduction financial) Global Stability of Banking Networks September 16, 2014 4 / 48 #12;Introduction Cause for financial

DasGupta, Bhaskar

122

Solution-Processed Dioctylbenzothienobenzothiophene-Based Top-Gate Organic Transistors with High Mobility, Low Threshold Voltage, and High Electrical Stability  

NASA Astrophysics Data System (ADS)

Dioctylbenzothieno[2,3-b]benzothiophene (C8-BTBT)-based organic field-effect transistors (OFETs) with a top-gate configuration, having fluoropolymer gate insulators, are fabricated by means of a spin-coating technique. The device fabrication is simple, and it enables us to obtain C8-BTBT FETs having high field-effect mobility (µFET), low threshold voltage (Vth), and high electrical stability. We fabricate 116 top-gate C8-BTBT FETs having µFET of 1.59+/-0.40 cm2 V-1 s-1 and Vth of -1.48+/-3.02 V, and the maximum µFET is approximately 3 cm2 V-1 s-1. No changes in the devices characteristics are observed after applying a negative gate bias stress of -1.2 MV/cm for 104 s.

Endo, Toshiyuki; Nagase, Takashi; Kobayashi, Takashi; Takimiya, Kazuo; Ikeda, Masaaki; Naito, Hiroyoshi

2010-12-01

123

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

124

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

PubMed

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. PMID:24289400

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

2013-11-01

125

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

SciTech Connect

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.

Wang, Qi; Wang, Junting; Lu, Qingyou, E-mail: qxl@ustc.edu.cn [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China) [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hou, Yubin [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China)] [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China)

2013-11-15

126

Seismic hazard evaluation for design and/or verification of a high voltage system  

SciTech Connect

The Venezuelan capital, Caracas, with a population of about 5 million, is within the area of contact of the Caribbean and South American tectonic plates. Since 1567, the valley where it lies and surroundings have been shaken by at leas six destructive events from different seismogenic sources. Electric energy is served to the city by a high voltage system consisting of 4 power stations, 20 substations (230 KV downwards) and 80 km of high voltage lines, covering an area of about 135 x 60 km{sup 2}. Given the variety of soil conditions, topographical irregularities and proximity to potentially active faults, it was decided to perform a seismic hazard study. This paper gives the results of that study synthesized by two hazard-parameter maps, which allow a conservative characterization of the acceleration on firm soils. Specific site coefficients allow for changes in soil conditions and topographical effects. Sites whose proximity to fault lines is less than about 2 km, require additional field studies in order to rule out the possibility of permanent ground displacements.

Grases, J.; Malaver, A. [Ingenieria de Consulta, Caracas (Venezuela); Lopez, S.; Rivero, P. [Electricidad de Caracas (Venezuela)

1995-12-31

127

High temperature stability of Hf-based gate dielectric stacks with rare-earth oxide layers for threshold voltage control  

Microsoft Academic Search

The thermal stability of DyOx\\/HfSiON and HoOx\\/HfSiON gate dielectric stacks on silicon was studied by scanning transmission electron microscopy techniques and correlated with their electrical characteristics. Intermixing of the rare-earth elements with the HfSiON was observed, but there was no diffusion into the interfacial SiO2. Rapid thermal annealing (1000 °C) produced little detectable change in the concentration profile of the

James M. Lebeau; Jesse S. Jur; Daniel J. Lichtenwalner; H. Spalding Craft; Jon-Paul Maria; Angus I. Kingon; Dmitri O. Klenov; Joël Cagnon; Susanne Stemmer

2008-01-01

128

User and process-driven dynamic voltage and frequency scaling  

Microsoft Academic Search

We describe and evaluate two new, independently-applicabl e power reduction techniques for power management on proces- sors that support dynamic voltage and frequency scaling (DV FS): user-driven frequency scaling (UDFS) and process-driven v olt- age scaling (PDVS). In PDVS, a CPU-customized profile is de- rived offline that encodes the minimum voltage needed to achi eve stability at each combination of

Bin Lin; Arindam Mallik; Peter A. Dinda; Gokhan Memik; Robert P. Dick

2009-01-01

129

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

PubMed Central

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 (1.51±0.70 mSv) and group B (2.59±1.24 mSv) were both lower than group C (4.92±2.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.10±0.41), group B (3.90±0.48) and group C (4.04±0.36) (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

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

2015-01-01

130

Evaluation of Digital Crosstalk Noise on Differential Input Voltage Controlled Oscillator  

NASA Astrophysics Data System (ADS)

With an increase in the operation frequency of complimentary metal oxide semiconductor (CMOS) circuits, a radio-frequency system-on-a-chip (RF-SOC) that integrates GHz-RF and large-scale digital circuits becomes a key device for wireless systems and high-speed networks. To develop high-performance RF-SOCs, high quality voltage controlled oscillators (VCOs) are required as local oscillators or clock generators, which operate in noisy environments suffering from crosstalk noise generated by digital circuits. A 0.25 µm CMOS test chip for a new differential-input VCO and a conventional single-input VCO was designed with on-chip CMOS logic noise sources and substrate noise detectors. The jitter and phase noise of the VCOs were measured to investigate the effect of substrate crosstalk noise. We confirmed that the differential-input VCO is robust to low-frequency noise in comparison with a conventional single-input VCO.

Toya, Akihiro; Murasaka, Yoshitaka; Ohmoto, Takafumi; Iwata, Atsushi

2008-04-01

131

Low Voltage Power Supply Incorporating Ceramic Transformer  

E-print Network

A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the cerami...

Imori, M

2007-01-01

132

Evaluation of approaches to active compressor surge stabilization  

Microsoft Academic Search

Recent work has shown that compression systems can be actively stabilized against the instability known as surge, thereby realizing a significant gain in system mass flow range. Ideally, this surge stabilization requires only a single sensor and a single actuator connected by a suitable control law. Almost all research to date has been aimed at proof of concept studies of

J. S. Simon; L. Valavani; A. H. Epstein; E. M. Greitzer

1993-01-01

133

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

SciTech Connect

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.

Stahl, S.M.

1994-12-30

134

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

NASA Astrophysics Data System (ADS)

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-?F/2 when ?F?Fbi by using electroreflectance to simulate PR, where ?F is the modulating field of the pump beam. In this work a method was devised to evaluate ?F by using photoinduced voltages Vs and, hence, the relation can be verified by PR itself. The ?Fs obtained by Vs are also consistent with those of using imaginary part of fast Fourier transform of PR spectra.

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

2002-04-01

135

A micromechanical DC-voltage reference  

Microsoft Academic Search

Prototype of a novel DC voltage reference has been constructed. A characteristic voltage of an electrostatically actuated micromechanical silicon device provides the reference voltage. Its stability relies on elastic properties of monocrystalline silicon. The device is suited for batch fabrication and may prove more stable than Zener voltage references

A. S. Oja; J. Kyynarainen; H. Seppa; T. Lampola

2000-01-01

136

Evaluation of the mechanical stability of a megavoltage imaging system using a new flat panel positioner  

NASA Astrophysics Data System (ADS)

Mega-Voltage systems are used in radiation oncology both for external radiation delivery and patient positioning prior to treatment. A pair of portal images compared with digitally reconstructed radiographs is currently the gold standard for positioning but new developments have made possible the use of Mega-Voltage Cone Beam CT for better 3D setup. The non-ideal imaging geometry of the treatment unit has a direct impact on both methods. It led to the use of a reticule attachment as reference for the scale and the isocenter position on the portal images. The reticule has limited precision and occasionally super-imposes anatomical information. As for Cone Beam, the image quality crucially depends on the knowledge of the scan geometry during the acquisition. The reproducibility of the detector position at each angle will affect the image reconstruction and determine how frequently geometrical calibration must be performed. The objectives of this study are to measure the flex of the detector and evaluate its reproducibility. A RID 1640 Perkin Elmer a-Si Flat Panel is installed on a Siemens Primus linear accelerator with a positioner similar the the one used in the Oncor product. Three original methods are used to investigate the behavior in space and time of the imaging system. A reticule and a Plumb Bob tip are placed along the line formed by the isocenter and the source. Their positions projected on the flat panel for different gantry positions are used to calculate the mechanical flex. Projection matrices obtained in a geometrical Cone Beam calibration are also used to quantify the flat panel sagging. Six full sets of data were acquired over a period of 5 months and recorded overall mechanical flexes of 1 and 3 mm for the transversal and longitudinal directions respectively. The absolute magnitude of the flat panel displacement varies slightly with the method used but the discrepancy stays within the laser precision used for alignment. The small standard deviations of the flat panel displacement (< 1 mm) suggest great stability over time and permits the clinical implementation of patient positioning without the reticule. More experiments on the positioner with the complete set of projection matrices need to be performed to characterize the long-term behavior of the system and to determinate how frequently the Cone Beam calibration needs to be done to conserve image quality. Future work will develop a daily QA protocol to detect possible collisions that would bring the Cone Beam imaging system out of geometrical calibration.

Morin, O.; Chen, J.; Aubin, M.; Pouliot, J.

2005-04-01

137

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 ...

138

Dynamic characteristics of noncontacting seal and evaluation of its effect on stability of rotor system  

NASA Astrophysics Data System (ADS)

Recent investigations on dynamic characteristics of the labyrinth seal and the pump seal are reviewed, and contributions of each element to stability of the rotor are illustrated for both seals. A method to evaluate the contribution of each element to the stability of a machine is presented. It is shown how to synthesize the rotor system by using the contribution of each element to stability.

Iwatsubo, Takuzo

139

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

NASA Technical Reports Server (NTRS)

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.

1980-01-01

140

Effects of Sample Storage on Biosolids Compost Stability and Maturity Evaluation  

E-print Network

Effects of Sample Storage on Biosolids Compost Stability and Maturity Evaluation L. Wu and L. Q. Ma-drying of soil sam-Compost stability and maturity are important parameters of com- ples is the most common practice (Bates, 1993), despitepost quality. To date, nearly all compost characterization has been

Ma, Lena

141

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)

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.

Aradilla, David; Gentile, Pascal; Ruiz, Vanesa; Gómez-Romero, Pedro; Wimberg, Jan; Iliev, Boyan; Schubert, Thomas J. S.; Sadki, Saïd; Bidan, Gérard

2015-03-01

142

Evaluation of the stability of gas hydrates in Northern Alaska  

USGS Publications Warehouse

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.

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

1987-01-01

143

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

NASA Astrophysics Data System (ADS)

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.

Powell, R. D.

2013-12-01

144

Evaluation of HAN-TEAN Stabilizers using Microcalorimetry  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

145

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 ...

146

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 ...

147

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

148

Experimental evaluation of actual delivered dose using mega-voltage cone-beam CT and direct point dose measurement  

SciTech Connect

Radiation therapy in patients is planned by using computed tomography (CT) images acquired before start of the treatment course. Here, tumor shrinkage or weight loss or both, which are common during the treatment course for patients with head-and-neck (H and N) cancer, causes unexpected differences from the plan, as well as dose uncertainty with the daily positional error of patients. For accurate clinical evaluation, it is essential to identify these anatomical changes and daily positional errors, as well as consequent dosimetric changes. To evaluate the actual delivered dose, the authors proposed direct dose measurement and dose calculation with mega-voltage cone-beam CT (MVCBCT). The purpose of the present study was to experimentally evaluate dose calculation by MVCBCT. Furthermore, actual delivered dose was evaluated directly with accurate phantom setup. Because MVCBCT has CT-number variation, even when the analyzed object has a uniform density, a specific and simple CT-number correction method was developed and applied for the H and N site of a RANDO phantom. Dose distributions were calculated with the corrected MVCBCT images of a cylindrical polymethyl methacrylate phantom. Treatment processes from planning to beam delivery were performed for the H and N site of the RANDO phantom. The image-guided radiation therapy procedure was utilized for the phantom setup to improve measurement reliability. The calculated dose in the RANDO phantom was compared to the measured dose obtained by metal-oxide-semiconductor field-effect transistor detectors. In the polymethyl methacrylate phantom, the calculated and measured doses agreed within about +3%. In the RANDO phantom, the dose difference was less than +5%. The calculated dose based on simulation-CT agreed with the measured dose within±3%, even in the region with a high dose gradient. The actual delivered dose was successfully determined by dose calculation with MVCBCT, and the point dose measurement with the image-guided radiation therapy procedure.

Matsubara, Kana, E-mail: matsubara-kana@hs.tmu.ac.jp [Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-ku Tokyo (Japan); Kohno, Ryosuke [National Cancer Center Hospital East, Chiba (Japan); National Cancer Center Research Institute, Chiba (Japan); Nishioka, Shie; Shibuya, Toshiyuki; Ariji, Takaki; Akimoto, Tetsuo [National Cancer Center Hospital East, Chiba (Japan); Saitoh, Hidetoshi [Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-ku Tokyo (Japan)

2013-07-01

149

Integrated high-voltage\\/Low-voltage MOS devices  

Microsoft Academic Search

A new high voltage device structure and a corresponding fabrication process have been developed. The device has a planar, integrable, closed geometry structure that utilizes a highly resistive polysilicon field relief electrode (field plate) to control device breakdown voltage and transconductance. The active device area is totally covered by polysilicon or metal, contributing to long term stability and reliability. The

Steven A. Buhler; David L. Heald; Ram R. Ronen; Terry Gannon; Patricia Elkins

1981-01-01

150

Voltage Drop  

NSDL National Science Digital Library

The first site with information on voltage drop is provided by Power and System Innovations on their Frequently Asked Questions: Voltage Drop (1) page. Visitors can read what voltage drop is, what causes it, what happens as a result of it, and what the maximum recommended voltage drop is. The second site, Basics of Electricity (2), is part of General Electric's Lighting for Business Web site. Through descriptions and illustrations, the site explains what voltage drop is and gives examples of how it is calculated using Ohm's law. The next site is a lab worksheet that is part of a class from the Electrical and Computer Engineering Department of Montana State University called Voltage Drop in Cables (3). The objective of the lesson is to determine the internal resistance of an extension cord and choose the proper wire size for a particular application. Students are given an explanation of the procedure and a number of questions to answer related to the exercise. The Oregon Building Congress offers the Lesson Plans (4) Web site and the downloadable Voltage Drop educational activity. The lesson, which is suggested to be contained within a unit on formulas and solving literal equations, explores the concept of voltage drop that is encountered in basic wiring. The fifth site entitled Explanation of Voltage Drop in a Series Circuit (5) is offered by the Horizons Electronic Lesson Plan Resource. The page describes voltage drop as an electronic concept, gives a formula determining voltage drop, provides a schematic that helps illustrate the concept, and offers a quiz and answer sheet. Next, from electrician.com, is the online Voltage Drop Calculator (6). Users input the type and size of wire being used, the voltage and phase, circuit length, and amp load to calculate voltage drop and several other parameters. The seventh site, entitled The Hazards of Voltage Drop (7), is provided within the Electrical Construction Maintenance Web site. The page describes how electrical equipment can overheat or even power down if it operates below its voltage rating. It also provides a thorough explanation of how to determine the load's operating voltage. The last site, maintained by Williamson Labs (8), is a comprehensive learning site called Elementary Electricity. Visitors will find a wealth of information here, including fun descriptions, graphics, and animations on all aspects of electricity including voltage drop.

151

REAL WORLD CRASH EVALUATION OF VEHICLE STABILITY CONTROL (VSC) TECHNOLOGY  

Microsoft Academic Search

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 1998-2002 were analyzed including 13,987 crash-involved study vehicles not equipped

G. Bahouth

152

Evaluation of degradation kinetics and physicochemical stability of tenofovir.  

PubMed

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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24817173

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

2015-03-01

153

Intrinsic Surface Stability in LiMn2-xNixO4-d (x=0.45, 0.5) High Volt-age Spinel Materials for Lithium Ion Batteries  

SciTech Connect

This work reports the surface stability of the high voltage Li ion cathode LiMn2-xNixO4- (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 PF6 to POF5 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.

Carroll, Kyler J [University of California, San Diego; Yang, Ming-Che [University of Florida, Gainesville; Veith, Gabriel M [ORNL; Dudney, Nancy J [ORNL; Meng, Ying Shirley [University of California, San Diego

2012-01-01

154

Measurement and protocol for evaluating video and still stabilization systems  

NASA Astrophysics Data System (ADS)

This article presents a system and a protocol to characterize image stabilization systems both for still images and videos. It uses a six axes platform, three being used for camera rotation and three for camera positioning. The platform is programmable and can reproduce complex motions that have been typically recorded by a gyroscope mounted on different types of cameras in different use cases. The measurement uses a single chart for still image and videos, the texture dead leaves chart. Although the proposed implementation of the protocol uses a motion platform, the measurement itself does not rely on any specific hardware. For still images, a modulation transfer function is measured in different directions and is weighted by a contrast sensitivity function (simulating the human visual system accuracy) to obtain an acutance. The sharpness improvement due to the image stabilization system is a good measurement of performance as recommended by a CIPA standard draft. For video, four markers on the chart are detected with sub-pixel accuracy to determine a homographic deformation between the current frame and a reference position. This model describes well the apparent global motion as translations, but also rotations along the optical axis and distortion due to the electronic rolling shutter equipping most CMOS sensors. The protocol is applied to all types of cameras such as DSC, DSLR and smartphones.

Cormier, Etienne; Cao, Frédéric; Guichard, Frédéric; Viard, Clément

2013-01-01

155

Distributed parallel computing architecture design philosophy for TTC evaluation with transient stability constraints  

Microsoft Academic Search

This paper presents a novel calculation framework for TTC evaluation with transient stability (TS) constraints with respect to an usual or a critical contingency set. The basic solution strategy for TTC evaluation is introduced, and the whole system architecture and computing flow are given in this paper. In order to implement the security margin of large-scale interconnected power system efficiently

Z. J. Guo; L. B. Shi; Z. X. Yao

2008-01-01

156

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...

157

Preliminary Study on Evaluation Indexes of Road-Region Ecosystem Stability  

Microsoft Academic Search

A scientific and rational evaluation on road-region ecosystem stability is the premise to properly deal with the relationship between highway constructing and ecological environment protecting to a continuable development. It is very important to properly select the evaluation indexes. Only on the basis of systematic analysis on highway environment problems and a rational indexes system, which can exactly extract the

Li Jianbo

2009-01-01

158

Evaluation of multiple management objectives for northeast Atlantic flatfish stocks: sustainability vs. stability of yield  

Microsoft Academic Search

This paper describes a simulation study that evaluated the ICES scientific advisory process used to recommend total allowable catches (TACs) for flatfish stocks. Particular emphasis is given to examining the effects on stock biomass, yield and stability of constraining interannual variation in TACs. A ¿management strategy evaluation¿ approach is used where an operating model is used to represent the underlying

L. T. Kell; M. A. Pastoors; R. D. Scott; M. T. Smith; Beek van F. A; C. M. O'Brien; G. M. Pilling

2005-01-01

159

Rapid evaluation and optimization of machine tools with position-dependent stability  

E-print Network

Rapid evaluation and optimization of machine tools with position-dependent stability Mohit Law efficient methodology to evaluate and improve dynamic performance of a machine tool at the design stage depth of cut are further influenced by the changing structural dynamics of the machine as the tool moves

Phani, A. Srikantha

160

Yield Performance and Stability Evaluation of Peanut Breeding Lines with the CSM-CROPGRO-Peanut Model  

Microsoft Academic Search

Multienvironment trials of crop breeding lines consume many resources. Crop models have a potential to assist in this process. The goal of this study was to evaluate the potential of the CSM- CROPGRO-Peanut model in assisting with yield performance and stability evaluation of peanut (Arachis hypogaea L.) breeding lines. Seventeen peanut lines were tested in 11 environments in Thailand during

B. Suriharn; A. Patanothai; K. Pannangpetch; S. Jogloy; G. Hoogenboom

2008-01-01

161

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

PubMed Central

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 1998–2002 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

Bahouth, G.

2005-01-01

162

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

PubMed Central

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

2013-01-01

163

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

PubMed

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

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

2015-04-14

164

Spillover in the Academy: Marriage Stability and Faculty Evaluations.  

ERIC Educational Resources Information Center

Studied the spillover between family and work by examining the link between marital status and work performance across marriage, divorce, and remarriage. A polynomial regression model was fit to the data from 78 evaluations of an individual professor, and a cubic curve through the 3 periods was statistically significant. (SLD)

Ludlow, Larry H.; Alvarez-Salvat, Rose M.

2001-01-01

165

Evaluation of the Cell Voltage of Electrolytic HI Concentration for Thermochemical Water-Splitting Iodine-Sulfur Process  

SciTech Connect

Breakdown of the cell voltage in the electro-dialysis process for concentrating HIx solution (HI-H{sub 2}O-I{sub 2} mixture) was preliminarily examined in an effort to clarify the optimal operation condition as well as to optimize the cell design for the application to the thermochemical water-splitting IS process for large-scale hydrogen production. Basic data such as electric resistance of HIx solution, overvoltage of the iodine-iodide ion redox reaction at graphite electrode, and the membrane voltage drop, were measured using HIx solution with composition of interest. Also, a methodology for estimating the cell voltage was discussed. The calculated cell voltage agreed well with the experimental one indicating the validity of the procedure adopted. (authors)

Tanaka, Nobuyuki; Yoshida, Mitsunori; Okuda, Hiroyuki; Sato, Hiroyuki; Kubo, Shinji; Onuki, Kaoru [Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Higash-iibaraki-gun Ibaraki 311-1393 (Japan)

2007-07-01

166

Voltage Controlled Voltage Source (VCVS)  

NSDL National Science Digital Library

Hosted by Clarkson University, this applet demonstrates a circuit that contains a voltage controlled voltage source (VCVS). The gain may be modified using the scroll bar. Even though brief, this resource can be used in a variety of different technical education classrooms.

Dorf, Richard C.

167

Evaluating Marie Byrd Land stability using an improved basal topography  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

168

High Voltage TAL Performance  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

169

Evaluation of factors affecting the solidification/stabilization of heavy metal sludge. Final report  

SciTech Connect

Solidification/stabilization 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 known to inhibit the setting and strength development properties of cement and pozzolan binding agents commonly used in solidification/stabilization processes. This study presents the results of an evaluation into the effects of ten interfering substances (oil, grease, lead, copper, zinc, sodium hydroxide, sodium sulfate, phenol, trichloroethylene, and hexachlorobenzene) on the physical and contaminant mobility properties of a solidified/stabilized heavy metal sludge. Three binder materials (Portland cement, lime/fly ash, and cement/fly ash) were used to solidify/stabilize a synthetic metal plating waste sludge containing substantial concentrations of four metals (cadmium, chromium, nickel, and mercury). The effects of these interfering materials were evaluated using five physical tests: unconfined compressive strength (UCS), cone index, bulk density, wet/dry cycling, and permeability. Contaminant leaching properties were evaluated using the US Environmental Protection Agency's Extraction Procedure test. Microchemical/micromorphological analyses were also performed on the treated sludges.... Cement, Metals, Fixation, Pozzolan, Hazardous waste, Solidification, Heavy metals, Stabilization, Interferences.

Bricka, R.M.; Jones, L.W.

1993-03-01

170

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...

171

Evaluation of First Swing Stability of a Large Power System With Various FACTS Devices  

Microsoft Academic Search

This paper presents a simple method of evaluating the first swing stability of a large power system in the presence of various flexible ac transmission system (FACTS) devices. First a unified power flow controller (UPFC) and the associated transmission line are considered and represented by an equivalent pi-circuit model. The above model is then carefully interfaced to the power network

M. H. Haque

2008-01-01

172

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

ERIC Educational Resources Information Center

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…

Chen, Guo-Hai; Watkins, David

2010-01-01

173

Minneapolis, July 24th-28th, 2011 On Dynamic Stability Evaluation of Functionally  

E-print Network

th-28th, 2011 #12;Minneapolis, July 24th-28th, 2011 Flexible Risers Should Provide · Easy, Tension and Torsion #12;Minneapolis, July 24th-28th, 2011 Flexible Riser ­ Concentric PolymericMinneapolis, July 24th-28th, 2011 On Dynamic Stability Evaluation of Functionally Graded Risers C

Paulino, Glaucio H.

174

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 ...

175

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...

176

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

SciTech Connect

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.

TORRES, T.D.

2000-08-24

177

Chemiluminescence in autoxidation of hydrocarbons. A method for fingerprinting and evaluation of oxidative stability  

SciTech Connect

Chemiluminescence (CL) was generated when mineral oils, lubricants, and synthetic hydrocarbons wer autoxidized at elevated temperature. CL intensity measurements were useful as a rapid method for evaluation of relative oxidative stabilities, and CL spectra served to differentiate and fingerprint hydrocarbon materials. Mineral oils which had been more severely refined to achieve a higher oxidative stability gave lower CL intensity. CL spectra and spectral changes with time were useful to differentiate oils according to their crude sources. CL measurements required less time than the conventional oxidation tests and a good agreement with ASTM D943 oxidation test could be shown. CL was also useful in monitoring and assessing service life left in used lubricants.

Spllners, I.J.; Hedenburg, J.F.

1985-09-01

178

Improvement of voltage stability and reduce power system losses by optimal GA-based allocation of multi-type FACTS devices  

Microsoft Academic Search

Modern power systems are prone to widespread failures. With the increase in power demand, operation and planning of large interconnected power system are becoming more and more complex, so power system will become less secure. Operating environment, conventional planning and operating methods can leave power system exposed to instabilities. Voltage instability is one of the phenomena which have result in

H. R. Baghaee; M. Jannati; B. Vahidi; S. H. Hosseinian; H. Rastegar

2008-01-01

179

Bulk Power System Dynamics and Control VI, August 22-27, 2004, Cortina d'Ampezzo, Italy Voltage Stability Enhancement via Model Predictive  

E-print Network

of the overload, lines forming the corridor will demand high levels of reactive power, causing voltages at both of the North American power system in August 2003 could have been avoided by tripping a relatively small amount in relieving system stress [2]. However counter-examples exist, with Figure 1 allowing a simple illustration

Hiskens, Ian A.

180

Analysis and Performance Evaluation of Interleaved DCM\\/CCM Boundary Boost PFC Converters Around Zero-Crossing of Line Voltage  

Microsoft Academic Search

In this paper, causes of improper interleaving of two DCM\\/CCM boundary boost PFC converters around zero crossing of the line voltage are analyzed. The converters have a master-slave relationship. The slave is synchronized to the turn-on instant of the master by using an open-loop interleaving method. It is shown that phase shifting the gate drive signals of the two stages

Claudio Adragna; Laszlo Huber; Brian T. Irving; M. M. Jovanovic

2009-01-01

181

Flight evaluation of the transonic stability and control characteristics of an airplane incorporating a supercritical wing  

NASA Technical Reports Server (NTRS)

A TF-8A airplane was equipped with a transport type supercritical wing and fuselage fairings to evaluate predicted performance improvements for cruise at transonic speeds. A comparison of aerodynamic derivatives extracted from flight and wind tunnel data showed that static longitudinal stability, effective dihedral, and aileron effectiveness, were higher than predicted. The static directional stability derivative was slower than predicted. The airplane's handling qualities were acceptable with the stability augmentation system on. The unaugmented airplane exhibited some adverse lateral directional characteristics that involved low Dutch roll damping and low roll control power at high angles of attack and roll control power that was greater than satisfactory for transport aircraft at cruise conditions. Longitudinally, the aircraft exhibited a mild pitchup tendency. Leading edge vortex generators delayed the onset of flow separation, moving the pitchup point to a higher lift coefficient and reducing its severity.

Matheny, N. W.; Gatlin, D. H.

1978-01-01

182

Soil stabilization using oil shale solid wastes: Laboratory evaluation of engineering properties  

SciTech Connect

Oil shale solid wastes were evaluated for possible use as soil stabilizers. A laboratory study was conducted and consisted of the following tests on compacted samples of soil treated with water and spent oil shale: unconfined compressive strength, moisture-density relationships, wet-dry and freeze-thaw durability, and resilient modulus. Significant increases in strength, durability, and resilient modulus were obtained by treating a silty sand with combusted western oil shale. Moderate increases in strength, durability, and resilient modulus were obtained by treating a highly plastic clay with combusted western oil shale. Solid waste from eastern shale can be used for soil stabilization if limestone is added during combustion. Without limestone, eastern oil shale waste exhibits little or no cementation. The testing methods, results, and recommendations for mix design of spent shale-stabilized pavement subgrades are presented. 11 refs., 3 figs., 10 tabs.

Turner, J.P.

1991-01-01

183

Evaluation of Rotordynamic Stability of a Steam Turbine Due to Labyrinth Seal Force  

NASA Astrophysics Data System (ADS)

This paper describes the evaluation of unstable vibration caused by the seal force, which is known as "Steam Whirl" in a steam turbine. Stability of a steam turbine is evaluated by complex eigenvalue analysis of rotordynamics model considering the dynamics of seals, rotor, bearings and pedestals. A commercial CFD program is employed to estimate the dynamic coefficients of labyrinth seal. The labyrinth seal of a large scales steam turbine is taken as an object of analysis and a 3D model with eccentric rotor is solved to obtain the rotordynamic force components. The rotordynamic force is derived by integrating the pressure on the rotor surface. Evaluation formula is formed from the results of numerical calculation, which is used to predict the dynamic coefficient of each seal in a steam turbine. Then rotordynamics model of total system including seal is constructed and stability is evaluated by complex eigenvalue analysis. This procedure is applied to the design of steam turbines and enables the optimization of the turbine structure considering the efficiency and stability.

Hirano, Toshio; Sasaki, Takashi; Sakakida, Hitoshi; Uchida, Tatsuro; Tsutsui, Masaji; Ikeda, Kazunori

184

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

PubMed

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

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

2015-01-01

185

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

PubMed Central

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

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

2015-01-01

186

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

187

A neural network-based method for voltage security monitoring  

SciTech Connect

In this paper, a neural network-based method is proposed for monitoring on-line voltage security of electric power systems. Using a dynamic model of the system, voltage stability is measured totally, considering a suitable stability index for the whole system, and locally, by defining appropriate voltage-margins for detecting the area of the system where the instability phenomenon arises. A three-layer feedforward neural network is trained to give, as outputs to a pre-defined set of input variables, the expected values of the above defined indices. The neural network is designed by using a fast learning strategy that allows the optimal number of hidden neurons to be easily determined. Moreover, it is shown that, in the operation mode, the system power-margin and the bus power-margins can be easily evaluated using the value of the voltage stability index given by the designed NN. The effectiveness of the proposed approach has been demonstrated on the IEEE 118-bus test system.

La Scala, M. [Univ. di Napoli (Italy). Dept. di Ingegneria Elettrica] [Univ. di Napoli (Italy). Dept. di Ingegneria Elettrica; Trovato, M.; Torelli, F. [Politecnico di Bari (Italy). Dept. di Elettrotecnica ed Elettronica] [Politecnico di Bari (Italy). Dept. di Elettrotecnica ed Elettronica

1996-08-01

188

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

SciTech Connect

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.

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

2000-09-28

189

Stability of Quantitative Evaluation Method of Liver Fibrosis Using Amplitude Distribution Model of Fibrotic Liver  

NASA Astrophysics Data System (ADS)

In the clinical diagnosis of liver fibrosis using ultrasound B-mode images, there are some differences between individual doctors' diagnosis results. Hence, the realization of a quantitative diagnosis method using ultrasonic echo signals is strongly required. The probability density function (PDF) of the echo signal envelope is an important factor for ultrasound tissue characterization (TC). To realize the quantitative diagnosis of the stage of liver fibrosis, we proposed an amplitude distribution model using two Rayleigh distributions. We have been studying the possibility of the quantitative estimation of liver fibrosis by using this model. In this paper, we present the evaluation results of liver fibrosis for clinical data using the amplitude distribution model. Then, we present the stability of the quantitative estimation method of liver fibrosis using the amplitude distribution model by a simulation, and compare the results using the simulation and clinical data. Stability evaluation has enabled the estimation of the progress of liver fibrosis considering statistical dispersion.

Igarashi, Yu; Yamaguchi, Tadashi; Hachiya, Hiroyuki

2011-07-01

190

Evaluation of Available Transfer Capability Using Transient Stability Constrained Line Flows  

NASA Astrophysics Data System (ADS)

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.

Uzoechi, Lazarus Okechukwu; Mahajan, Satish M.

2014-01-01

191

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

SciTech Connect

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.

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

1982-09-01

192

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)

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.

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

2014-12-01

193

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

194

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)

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.

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

2014-06-01

195

Stability evaluation of systematic effects in a compensated multi-pole mercury trapped ion frequency standard  

Microsoft Academic Search

A compensated multi-pole linear ion trap standard (LITS) using trapped 199Hg+ has recently demonstrated a fractional frequency deviation from the laser-cooled primary standards and the post-processed version of TAI known as TT(BIPM) of < 2.7(0.4)x10-17\\/day over a 9-month period. A subsequent stability evaluation performed after the 9-month comparison is in statistical agreement with the measured instability. We will describe the

E. A. Burt; S. Taghavi; J. D. Prestage; R. L. Tjoelker

2008-01-01

196

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

Microsoft Academic Search

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°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

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

1982-01-01

197

Microbial stability evaluation of cement-based waste forms at different waste to cement ratio  

Microsoft Academic Search

An evaluation of the effect of differences in chromium nitrate to cement ratio on the microbial stability of a chromium nitrate\\/cement waste form, as reflected in the leaching of chromium, calcium, magnesium and aluminum; was carried out in this study. An increase in the proportion of chromium in the waste form from 4.8 to 8.7% had no noticeable effect on

Michael A Idachaba; Kafui Nyavor; Nosa O Egiebor

2003-01-01

198

Evaluation of stabilization\\/solidification of an inorganic wood-preserving waste. Final report  

Microsoft Academic Search

This report presents the results of testing performed on a stabilized\\/solidified (S\\/S) inorganic wood-preserving waste. The contaminants found in the waste are primarily arsenic and chromium. Three S\\/S processes were evaluated in this study. They include the following: (a) a cement process, (b) a kiln dust process, and (c) a hme\\/fly ash process. Physical and leaching characteristics of the S\\/S

M. G. Channell; T. T. Kosson

1993-01-01

199

Evaluation of stabilization/solidification of an inorganic wood-preserving waste. Final report  

SciTech Connect

This report presents the results of testing performed on a stabilized/solidified (S/S) inorganic wood-preserving waste. The contaminants found in the waste are primarily arsenic and chromium. Three S/S processes were evaluated in this study. They include the following: (a) a cement process, (b) a kiln dust process, and (c) a hme/fly ash process. Physical and leaching characteristics of the S/S waste materials were evaluated. Physical characteristics were evaluated using the unconfined compressive strength test. The waste-leaching characteristics were evaluated using the toxicity characteristic leaching procedure (TCLP). Physical test results showed that S/S waste developed 28-day strengths ranging from 44 to 916 psi. Results of the chemical leach tests showed that S/S did reduce the amount of arsenic and chromium found in the extract but the levels were not met for the TCLP test.... Contaminant immobilization, Waste disposal, Hazardous waste, Wood preserving, Solidification.

Channell, M.G.; Kosson, T.T.

1993-04-01

200

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

SciTech Connect

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.

Shanfield, Z.; Moriwaki, M.M.

1987-12-01

201

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

USGS Publications Warehouse

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.

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

202

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

NASA Astrophysics Data System (ADS)

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.

Nalbantoglu, Zalihe; Tawfiq, Salma

2006-08-01

203

Development of an extemporaneous oral liquid formulation of oxandrolone and its stability evaluation.  

PubMed

Many references exist in the literature identifying the usefulness of oxandrolone in treating muscle wasting due to various conditions including severe burns. However, there is an absence of dosage form alternatives as it is only available as tablets. The dose for children is weight based (0.1 mg/kg) which is difficult to achieve with the currently available tablets of 2.5 mg and 10 mg. The literature provides ample evidence of clinical importance but little guidance on extemporaneous oral liquid formulation of oxandrolone. In order to develop and validate an extemporaneous liquid formulation, suspensions of oxandrolone were developed using locally available (New Zealand) vehicles. Combinations of these vehicles with ethanol, as advised in some articles were also tried. Assay method was developed for oxandrolone using High Performance Liquid Chromatography (HPLC) and Mass Spectroscopy (LC-MS). The formulations were evaluated for stability as per the International Conference on Harmonization (ICH) stability guidelines. They were observed for physical and chemical stability at different time points over a period of 28 days. A stable and validated liquid formulation of oxandrolone has been developed which can be made under the hospital and community pharmacy conditions. The formula utilises commercially available oxandrolone tablets, crushed and dispersed in Simple Syrup BP or Orablend(®) vehicle. The formulation has confirmed stability for 21 days and can be easily made with locally available vehicles. PMID:21764219

Garg, Alka; Garg, Sanjay; She, Richard Wong

2011-11-01

204

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

PubMed

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

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

2013-03-01

205

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

NASA Technical Reports Server (NTRS)

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.

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

206

Solution-processable, low-voltage, and high-performance monolayer field-effect transistors with aqueous stability and high sensitivity.  

PubMed

Low-voltage, low-cost, high-performance monolayer field-effect transistors are demonstrated, which comprise a densely packed, long-range ordered monolayer spin-coated from core-cladding liquid-crystalline pentathiophenes and a solution-processed high-k HfO2 -based nanoscale gate dielectric. These monolayer field-effect transistors are light-sensitive and are able to function as reporters to convert analyte binding events into electrical signals with ultrahigh sensitivity (?10 ppb). PMID:25678213

Chen, Hongliang; Dong, Shaohua; Bai, Meilin; Cheng, Nongyi; Wang, Hao; Li, Mingliang; Du, Huiwen; Hu, Shuxin; Yang, Yanlian; Yang, Tieying; Zhang, Fan; Gu, Lin; Meng, Sheng; Hou, Shimin; Guo, Xuefeng

2015-03-01

207

The idea of PGA stream computations for soil slope stability evaluation  

NASA Astrophysics Data System (ADS)

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.

Tran, Chi; Srokosz, Piotr

2010-09-01

208

Evaluation of the stability and quality of sleep using Hjorth's descriptors.  

PubMed

Hjorth's descriptors (NSD) (activity, mobility, and complexity) provide a useful tool for evaluating micro- and macrostructural elements of sleep. In rats, the automatic analysis of sleep recordings by means of NSD calculated from SM and Vis derivations allow different sleep stages to be discriminated. Activity distribution over the total recording permits the definition of a global effect on the EEG. Moreover, the quality of sleep can be evaluated by the variations of the SM activity distribution by considering different classes of amplitude. Index and rate of unstable amplitude segments (UAS) constitute useful parameters to analyse the stability and quality of sleep with different models of insomnia and after pharmacological treatment. The UAS in rats can be compared to CAPs in humans. The NSD are also able to define quality and stability of human sleep. EEG analysis using NSD provides a novel perspective for the analysis of the stability and quality of rat and human sleep. This microstructural analysis of sleep appears to be a useful tool for pharmaco-EEG studies. PMID:8248358

Depoortere, H; Francon, D; Granger, P; Terzano, M G

1993-10-01

209

EVALUATING THE EFFECTIVENESS OF STREAMBANK STABILIZATION TECHNIQUES FOR REDUCING BANK EROSION ON THE UPPER CLARK FORK RIVER, WESTERN MONTANA  

Microsoft Academic Search

Lateral channel movement on the upper Clark Fork River in western Montana has resulted in loss of valuable agricultural land and delivery of sediment and mine tailings into the river. In spring 1996, we initiated a study to evaluate the effectiveness of streambank stabilization techniques to reduce bank erosion. This study examines the effectiveness of 21 different bioengineering stabilization techniques

Donna DeFrancesco; Paul L. Hansen

2000-01-01

210

Evaluation of two lead-based paint removal and waste stabilization technology combinations on typical exterior surfaces  

Microsoft Academic Search

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 media (coal slag and mineral sand) paint debris thereby reducing the leachable lead content. The lead-based paint removal

Alva E Daniels; John R Kominsky; Patrick J Clark

2001-01-01

211

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...

212

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

NASA Astrophysics Data System (ADS)

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.

Nair, Nirmal-Kumar

213

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

214

Evaluation of the geological relationships to gas hydrate formation and stability  

SciTech Connect

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.

Not Available

1986-01-01

215

The potential of accelerometers in the evaluation of stability of total knee arthroplasty.  

PubMed

An accelerometer attached to the anterior proximal tibia was investigated as an evaluation of knee stability of Total Knee Arthroplasty (TKA) patients while performing daily activities. Acceleration data of 38 TKA knees with a minimum follow up of 6months were compared with 34 control knees. The activities performed were: walking three steps forward and coming to a sudden stop; turning in the direction of non-tested knee; sit-to-stand; and stepping up and down from a 7 inch step. The acceleration results showed significant differences between TKA and controls while stepping down and while turning in the non-tested knee direction. The higher accelerations with the TKA group may have represented an objective measure of stability, even if this was not directly discernible to the patient. PMID:23122873

Khan, Humera; Walker, Peter S; Zuckerman, Joseph D; Slover, James; Jaffe, Fredrick; Karia, Raj J; Kim, Joo H

2013-03-01

216

Evaluation of Pretilt Angle and Polar Anchoring Strength of Amorphous Alignment Liquid Crystal Display from Capacitance Versus Applied Voltage Measurement  

Microsoft Academic Search

The pretilt angle and the anchoring strength are important parameters in liquid crystal displays (LCDs). However, in the case of amorphous LCDs (a-LCDs), it is difficult to evaluate these parameters by means of conventional measurement method due to non-uniformity of the LC directors. In this paper, we report the simultaneous evaluation method of the pretilt angle and the polar angle

Yasuo Toko; Tadashi Akahane

2001-01-01

217

SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS  

SciTech Connect

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.

MCSHANE DS

2010-03-25

218

Low operation voltage and high thermal stability of a WSi2 nanocrystal memory device using an Al2O3/HfO2/Al2O3 tunnel layer  

NASA Astrophysics Data System (ADS)

A WSi2 nanocrystal nonvolatile memory device was fabricated with an Al2O3/HfO2/Al2O3 (AHA) tunnel layer and its electrical characteristics were evaluated at 25, 50, 70, 100, and 125 °C. The program/erase (P/E) speed at 125 °C was approximately 500 ?s under threshold voltage shifts of 1 V during voltage sweeping of 8 V/-8 V. When the applied pulse voltage was ±9 V for 1 s for the P/E conditions, the memory window at 125 °C was approximately 1.25 V after 105 s. The activation energies for the charge losses of 5%, 10%, 15%, 20%, 25%, 30%, and 35% were approximately 0.05, 0.11, 0.17, 0.21, 0.23, 0.23, and 0.23 eV, respectively. The charge loss mechanisms were direct tunneling and Pool-Frenkel emission between the WSi2 nanocrystals and the AHA barrier engineered tunneling layer. The WSi2 nanocrystal memory device with multi-stacked high-K tunnel layers showed strong potential for applications in nonvolatile memory devices.

Uk Lee, Dong; Jun Lee, Hyo; Kyu Kim, Eun; You, Hee-Wook; Cho, Won-Ju

2012-02-01

219

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

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.

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

220

Evaluation of the probability of arrester failure in a high-voltage transmission line using a Q learning artificial neural network model  

NASA Astrophysics Data System (ADS)

One of the most popular methods of protecting high voltage transmission lines against lightning strikes and internal overvoltages is the use of arresters. The installation of arresters in high voltage transmission lines can prevent or even reduce the lines' failure rate. Several studies based on simulation tools have been presented in order to estimate the critical currents that exceed the arresters' rated energy stress and to specify the arresters' installation interval. In this work artificial intelligence, and more specifically a Q-learning artificial neural network (ANN) model, is addressed for evaluating the arresters' failure probability. The aims of the paper are to describe in detail the developed Q-learning ANN model and to compare the results obtained by its application in operating 150 kV Greek transmission lines with those produced using a simulation tool. The satisfactory and accurate results of the proposed ANN model can make it a valuable tool for designers of electrical power systems seeking more effective lightning protection, reducing operational costs and better continuity of service.

Ekonomou, L.; Karampelas, P.; Vita, V.; Chatzarakis, G. E.

2011-04-01

221

Comparison of rancimat evaluation modes to assess oxidative stability of fish oils  

Microsoft Academic Search

Two Rancimat evaluation modes, the induction period (IP), and the time needed to achieve a selected difference in conductivity\\u000a (t?K) were compared for assessing relative stability of anchovy, sardine, and hake liver oils. Mean coefficients of variation\\u000a were 2.5 and 2.4% for IP and t?K values, respectively, for oils oxidized in the range 55–90C. Natural logarithms of IP and\\u000a t?K

Eduardo Méndez; Julio Sanhueza; Hernán Speisky; Alfonso Valenzuela

1997-01-01

222

Stability analysis of QRS features to evaluate signal quality for multi-lead QRS dectection.  

PubMed

In automated ECG monitoring, QRS detection performance is dependent on noise measurements on individual leads. A new signal quality measurement based on stability analysis of QRS complex features has been developed to assess individual ECG lead quality. The new method was evaluated on the records of the MIT-BIH arrhythmia and NST databases. Results showed that the new signal quality measurement can be used to accurately assess ECG signal quality and can be easily incorporated into an existing multi-lead QRS detection algorithm for performance improvement. PMID:22255159

Zhang, Zhe; Lall, Carolyn; Chen, Yu

2011-01-01

223

Health-hazard evaluation report HETA 86-339-1741, EMCO High Voltage Company, Sutter Creek, California  

SciTech Connect

Possible exposure to several chemical substances during the fabrication of power-supply modules was investigated at the EMCO High Voltage Company, Sutter Creek, California, at the request of an employee. Environmental air samples were collected during the coating and developing process and during the epoxy potting operation. Samples were analyzed for chlorobenzene and xylenes; no overexposures were registered. No overexposure was observed to butyl-glycidyl-ether and no detectable levels of epichlorohydrin, cyclohexanone, 2-methoxyethanol, or 2-ethoxyethanol were found. During the pot soldering operation there was a potential for exposure to the fluxing agent, 3% hydrochloric-acid, and the operator had complained of throat and nose irritation. The author recommends that the fabrication operator wear protective gloves during coating and developing of copper boards. Gloves and goggles should be worn when weighing out the sodium-persulfate and when removing panels from the bench top etcher. Local exhaust ventilation with a movable duct should be used during the pot soldering operation.

Belanger, P.L.

1986-10-01

224

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

225

Evaluation of atomic force microscopy: comparison with electrical CD metrology and low-voltage scanning electron microscopy  

NASA Astrophysics Data System (ADS)

With the increasing move towards measurement of smaller and smaller dimensions, the reliability of existing metrology approaches is begin called into question. The most widely used approach for CD measurement in a fabrication environment is the use of Low Voltage Scanning Electron Microscopy. SEMs are routinely used in industry for top-down measurements of lines, spaces, and contacts in the production line. The destructive approach of cross section SEMs is used for trouble shooting and analysis. Electrical CD measurements are also routinely used to measure the CDs of conducting layers in the production environment. However, electrical CD metrology is not appropriate for the majority of surfaces that are non-conductive, such as those with photoresist. It has been speculated for a while n ow that the AFM can provide a viable alternative by overcoming all the drawbacks of the other metrology techniques. This paper address this issue and discusses the relative merits of the AFM as compared to the others. The measurement bias between the three techniques on isolated line features ranging from 0.1 to 0.3 microns is compared. The ability of the AFM to measure profiles is discussed.

Yedur, Sanjay K.; Singh, Bhanwar

1999-06-01

226

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

SciTech Connect

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.

Carroll, Kyler J [University of California, San Diego; Yang, Ming-Che [University of Florida, Gainesville; Veith, Gabriel M [ORNL; Dudney, Nancy J [ORNL; Meng, Ying Shirley [University of California, San Diego

2012-01-01

227

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

PubMed Central

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 (?=.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

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

2011-01-01

228

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

PubMed

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 (Tm) 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

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

2014-12-10

229

Microbial stability evaluation of cement-based waste forms at different waste to cement ratio.  

PubMed

An evaluation of the effect of differences in chromium nitrate to cement ratio on the microbial stability of a chromium nitrate/cement waste form, as reflected in the leaching of chromium, calcium, magnesium and aluminum; was carried out in this study. An increase in the proportion of chromium in the waste form from 4.8 to 8.7% had no noticeable effect on microbial stability, with the total chromium leached essentially unchanged. Further increases in the proportion of chromium in the waste form from 8.7 to 10.7%, and from 10.7 to 15.9% resulted in a substantial decrease in microbial stability, with 3-fold and 1.3-fold increase in the total chromium leached, respectively, observed. For calcium, increases in the chromium proportion were accompanied with increases in the total calcium leached even though the increases were not in direct proportion to the increases in chromium proportion. For magnesium and aluminum, increases in the proportion of chromium within the range 4.8-10.7% were accompanied with increases in the total respective metals leached, with minor variation for each metal. On the whole, the maximum percentage chromium leached from the different waste forms was substantially lower than those of the other metals. PMID:12493216

Idachaba, Michael A; Nyavor, Kafui; Egiebor, Nosa O

2003-01-31

230

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

PubMed

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

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

231

Evaluation of higher distribution and/or utilization voltages. Second interim report (March 1979): identification of components and parameters for cost and energy-efficiency analysis  

SciTech Connect

This interim report provides documentation on the second task, Identification of Components and Parameters for Cost and Energy-Efficiency Analysis, of DOE Contract No. ET-78-C-01-2866, Evaluation of Higher Distribution and/or Utilization Voltages. The work performed under this task includes an identification of the elements of the distribution/utilization system, a characterization of the distribution elements and a characterization of end use elements. The purpose of this task is to identify the distribution and utilization system elements which will be subjected to a detailed analysis and computer modeling in later tasks. The elements identified are characterized in terms of their interface with other elements in the system and with respect to their energy consumption, efficiency, and costs. A major output of this task is a list of elements to be modeled under Task 3 and a set of specifications for the computer model to be developed under that task.

Not Available

1981-04-01

232

Design and flight performance evaluation of the Mariners 6, 7, and 9 short-circuit current, open-circuit voltage transducers  

NASA Technical Reports Server (NTRS)

The purpose of the short-circuit voltage transducer is to provide engineering data to aid the evaluation of array performance during flight. The design, fabrication, calibration, and in-flight performance of the transducers onboard the Mariner 6, 7 and 9 spacecrafts are described. No significant differences were observed in the in-flight electrical performance of the three transducers. The transducers did experience significant losses due to coverslides or adhesive darkening, increased surface reflection, or spectral shifts within coverslide assembly. Mariner 6, 7 and 9 transducers showed non-cell current degradations of 3-1/2%, 3%, and 4%, respectively at Mars encounter and 6%, 3%, and 4-12%, respectively at end of mission. Mariner 9 solar Array Test 2 showed 3-12% current degradation while the transducer showed 4-12% degradation.

Patterson, R. E.

1973-01-01

233

A battery-based, low-noise voltage source  

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

234

A battery-based, low-noise voltage source.  

PubMed

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

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

2010-06-01

235

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

PubMed

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 back scattering and transmission of particulates dispersed in solution. The formulations were evaluated by measuring the variation of physicochemical properties of colloids and suspensions as a function of back scattering and transmission modifications. In addition, the release profile of Iloprost isotonic solution from the biomedical device was evaluated. PMID:25381994

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

2014-11-10

236

Evaluation of the stability of enterovirus 71 virus-like particle.  

PubMed

Enterovirus 71 (EV71) is responsible for the outbreaks of hand-foot-and-mouth disease that caused significant mortality in children, but no vaccine is available yet. EV71 virus-like particle (VLP) is the empty capsid consisting of viral structural proteins but can elicit potent immune responses, rendering VLP a promising EV71 vaccine candidate. To evaluate whether VLP remains stable after long-term storage, which is crucial for advancing the VLP vaccine to the clinical setting, we evaluated the effects of NaCl concentration, buffers and temperatures on the VLP stability. We first validated the use of dynamic light scattering (DLS) for measuring the hydrodynamic diameter (?30-35 nm) of VLP, which was close to the VLP diameter (?25-27 nm) as measured by transmission electron microscopy (TEM). Using these techniques, we found that EV71 VLP remained stable for 5 months in sodium phosphate (NaPi) buffers with various NaCl concentrations. EV71 VLP also remained morphologically stable in NaPi, citrate and TE(+) buffers for 5 months, yet the enzyme-linked immunosorbent assay (ELISA) revealed that the VLP stored in citrate and TE(+) buffers partially lost the immunogenicity after 5 months. In contrast, the VLP stored in the NaPi buffer at 4°C remained stable macroscopically and microscopically for 5 months, as judged from the DLS, TEM and ELISA. The VLP stored at 25°C and 37°C also retained stability for 1 month, which would obviate the need of a cold chain during the shipping. These data altogether proved the stability of EV71 VLP and suggested that the VLP is amenable to bioprocessing and storage. PMID:24140131

Lin, Shih-Yeh; Chung, Yao-Chi; Chiu, Hsin-Yi; Chi, Wei-Kuang; Chiang, Bor-Luen; Hu, Yu-Chen

2014-03-01

237

Nanoemulsion stability: experimental evaluation of the flocculation rate from turbidity measurements  

E-print Network

The coalescence of liquid drops induces a higher level of complexity compared to the classical studies about the aggregation of solid spheres. Yet, it is commonly believed that most findings on solid dispersions are directly applicable to liquid mixtures. Here, the state of the art in the evaluation of the flocculation rate of these two systems is reviewed. Special emphasis is made on the differences between suspensions and emulsions. In the case of suspensions, the stability ratio is commonly evaluated from the initial slope of the absorbance as a function of time under diffusive and reactive conditions. Puertas and de las Nieves (1997) developed a theoretical approach that allows the determination of the flocculation rate from the variation of the turbidity of a sample as a function of time. Here, suitable modifications of the experimental procedure and the referred theoretical approach are implemented in order to calculate the values of the stability ratio and the flocculation rate corresponding to a dodecane-in-water nanoemulsion stabilized with sodium dodecyl sulfate. Four analytical expressions of the turbidity are tested, basically differing in the optical cross section of the aggregates formed. The first two models consider the processes of: a) aggregation (as described by Smoluchowski) and b) the instantaneous coalescence upon flocculation. The other two models account for the simultaneous occurrence of flocculation and coalescence. The latter reproduce the temporal variation of the turbidity in all cases studied (380 \\leq [NaCl] \\leq 600 mM), providing a method of appraisal of the flocculation rate in nanoemulsions.

Kareem Rahn-Chique; Antonio M. Puertas; Manuel S. Romero-Cano; Clara Rojas; German Urbina-Villalba

2012-05-21

238

On the effect of non-carbon nanostructured supports on the stability of Pt nanoparticles during voltage cycling: A study of TiO2 nanofibres  

NASA Astrophysics Data System (ADS)

Electrospun carbon and Nb-doped TiO2 nanofibres (CNFs, TNFs) have been investigated as electrocatalyst supports for polymer electrolyte membrane fuel cells (PEMFC). The optimal Nb doping amount has been identified for TNFs, and thermal treatment of titanium oxide fibres optimised to balance the surface area and electronic conductivity requirements. The most highly conducting material is characterised by a high concentration of surface Ti3+ and Nb4+ (and oxygen vacancies). Pt nanoparticles of average diameter of 2.3 nm were loaded onto 10%at Nb doped-TiO2, retained as the best candidate for further electrochemical analysis, and on CNFs, using a microwave-assisted polyol method. Significantly higher electrochemically active surface area was retained after voltage cycling to 1.2 V for Pt supported on TNF (73%) than on CNFs, where only 8% of the original ECSA was conserved after 1000 voltammetric cycles. The mass activity was also slightly higher for the titanium oxide based electrodes in the oxygen reduction reaction.

Savych, I.; Bernard d'Arbigny, J.; Subianto, S.; Cavaliere, S.; Jones, D. J.; Rozière, J.

2014-07-01

239

Evaluation of interface shear strength of composite liner system and stability analysis for a landfill lining system in Thailand  

Microsoft Academic Search

The paper presents the case history of laboratory evaluation of the interface shear strength properties of various interfaces encountered in a modern day landfill with emphasis on proper simulation of field conditions and subsequent use of these results in the stability analyses of liner system. Over 70 large direct shear tests were systematically conducted to evaluate the interface shear strength

D. T. Bergado; G. V. Ramana; H. I. Sia; Varun

2006-01-01

240

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

SciTech Connect

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.

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

1991-05-01

241

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

SciTech Connect

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.

Maleki, H. [Maleki Technologies Inc., Spokane, WA (United States)

1998-07-01

242

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

SciTech Connect

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.

Wu Chunyong; Wicks, Douglas A. [School of Polymers and High Performance Materials, 118 College Drive 10076, University of Southern Mississippi, Hattiesburg, Mississippi 39406 (United States)

2005-06-15

243

AC system stability analysis and assessment for Shipboard Power Systems  

E-print Network

frames of SPS dynamics are presented. Stability problems during SPS reconfiguration are classified as long-term stability problems. Since angle stability is strongly maintained in SPS, voltage stability is studied in this dissertation for SPS stability...

Qi, Li

2006-04-12

244

Capacitance-voltage spectroscopy of silicon nanodots  

NASA Astrophysics Data System (ADS)

Frequency-dependent capacitance-voltage spectroscopy was applied to investigate the carrier transport dynamics in a silicon nanodots resonant tunneling device structure. Two negative differential resistance (NDR) regions in the current-voltage characteristics were found in this investigated structure. Two anomalous regions were also found in the capacitance-voltage spectroscopy, which coincide with the NDR regions in the current-voltage characteristics. The origin of the anomalous phenomenon was attributed to the mesoscopic quantum capacitance due to the holes transport through the energy states associated with the Si nanodots. An equivalent circuit model was proposed to quantitatively evaluate the frequency dependence of the capacitance-voltage spectroscopy.

Su, Alex Yu-Kwen; Hwang, H. L.; Pilkuhn, M. H.; Pei, Z.

2005-02-01

245

Evaluation of global warming impacts for different levels of stabilization as a step toward determination of the long-term stabilization target  

Microsoft Academic Search

In order to estimate the benefit attributable to alleviating global warming for a kind of cost–benefit analysis of global\\u000a warming mitigation, global warming impacts were quantitatively evaluated for a pathway of unmitigated CO2 emissions and three pathways to stabilize the atmospheric CO2 concentration at different levels, keeping unchanged the assumed conditions on population and GDP growths, although the GDP\\u000a losses

Ayami Hayashi; Keigo Akimoto; Fuminori Sano; Shunsuke Mori; Toshimasa Tomoda

2010-01-01

246

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

SciTech Connect

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.

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

2012-08-01

247

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

PubMed

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

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

2011-04-15

248

Optimization of madecassoside liposomes using response surface methodology and evaluation of its stability.  

PubMed

Polar compounds with large molecular weight have poor membrane permeability, liposomes can promote drugs to penetrate epidermis and remain or release at dermis. Madecassoside (MA) exhibits powerful potency in treatment of skin disorders such as wound healing, scar management, and psoriasis, but it is not easy to penetrate epidermis for its hydrophilic nature. The aim of this work is to get the optimum process conditions and evaluate physicochemical properties and physical stability of MA liposomes. In order to avoid this disadvantage and maintain long term drug storage, MA Liposomes were designed to achieve optimum preparation conditions using response surface methodology (RSM) in our experiment. The process and formulation variables were optimized by achieving maximum drug encapsulation efficiency. The optimum conditions were 0.4424 g of madecassoside, 8.174 of ratio of egg yolk lecithin to cholesterol, 65 s of ultrasonic time. The results of particle size, zeta potential and encapsulation efficiency of madecassoside liposomes were 293 nm, -35.6 mV, and 40.90%, respectively, on the basis of the above optimum conditions. According to the morphology of liposomes and encapsulation efficiency of triplicate experiments conducted at optimum conditions, MA liposomes obtained by this optimized formulation had characters of favorable repeatability and proper particle size. The physical stability tests of MA liposomes indicated that its suitable storage temperature was at 4°C with higher encapsulation efficiency. PMID:25014372

Wang, Huijuan; Liu, Meifeng; Du, Song

2014-10-01

249

Evaluation of the stability and antimicrobial activity of an ethanolic extract of Libidibia ferrea  

PubMed Central

Biofilm is a dense, whitish, noncalcified aggregate of bacteria, with desquamated epithelial cells and food debris creating conditions for an imbalance of resident oral microflora and favoring the destruction of hard and soft tissues by development of caries and gingivitis. The aim of this study was to obtain and characterize an extract of Libidibia ferrea, ex Caesalpinia ferrea L. and to evaluate its feasibility for formulation as a mouthwash, according to current legislation. For this purpose, pH, sedimentation, density, and stability were evaluated, along with microbiological testing of the extract. The microbiological test was used to verify the presence of Staphylococcus aureus, Pseudomonas aeruginosa, fungi, yeasts, coliforms, and minimum inhibitory concentrations of Streptococcus mutans and Streptococcus oralis strains. Characterization, microbiological evaluation, and minimum inhibitory concentration results were tabulated and described using descriptive statistics. The L. ferrea extract showed stable characteristics, product quality, and antibacterial activity against the microorganisms tested irrespective of experimental time intervals. According to these results, it can be concluded that formulation of a mouthwash containing L. ferrea extract to control biofilm is feasible, but further studies are needed. PMID:24501546

de Oliveira Marreiro, Raquel; Bandeira, Maria Fulgência Costa Lima; de Souza, Tatiane Pereira; de Almeida, Mailza Costa; Bendaham, Katiana; Venâncio, Gisely Naura; Rodrigues, Isis Costa; Coelho, Cristiane Nagai; Milério, Patrícia Sâmea Lêdo Lima; de Oliveira, Glauber Palma; de Oliveira Conde, Nikeila Chacon

2014-01-01

250

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

PubMed

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

Rodrigues, Susana; Cordeiro, Clara; Seijo, Begoña; Remuñán-López, Carmen; Grenha, Ana

2015-06-01

251

Evaluation of the Lifetime and Thermal Conductivity of Dysprosia-Stabilized Thermal Barrier Coating Systems  

NASA Astrophysics Data System (ADS)

The aim of this study was the further development of dysprosia-stabilized zirconia coatings for gas turbine applications. The target for these coatings was a longer lifetime and higher insulating performance compared to today's industrial standard thermal barrier coating. Two morphologies of ceramic top coat were studied: one using a dual-layer system and the second using a polymer to generate porosity. Evaluations were carried out using a laser flash technique to measure thermal properties. Lifetime testing was conducted using thermo-cyclic fatigue testing. Microstructure was assessed with SEM and Image analysis was used to characterize porosity content. The results show that coatings with an engineered microstructure give performance twice that of the present reference coating.

Curry, Nicholas; Markocsan, Nicolaie; Östergren, Lars; Li, Xin-Hai; Dorfman, Mitch

2013-08-01

252

Nanostructured lipid carriers based nanogel for meloxicam delivery: mechanistic, in-vivo and stability evaluation.  

PubMed

Abstract Aim: Our investigation was aimed to investigate the potential suitability of meloxicam-loaded nanostructured lipid carriers (MLX-NLC) gel for topical application. Main methods: MLX-NLC gel was prepared and in vivo skin penetration ability of the NLC gel was evaluated using confocal laser scanning microscopy. We studied the effect of MLX-NLC gel on the changes in lipid profile of skin to get an insight into its skin penetration enhancement mechanism. Acetic acid induced writhing test was performed to evaluate the analgesic effect. Drug concentration-time profile of MLX in rat plasma and skin after topical and oral treatment with MLX-NLC gel and oral MLX-solution, respectively, was observed. MLX-NLC gel was subjected to primary skin irritation test, sub-acute dermal toxicity study. Storage stability of MLX-NLC gel was also assessed for 90 days. Key findings: NLC gel was effective in permeating Rhodamine 123 to deeper layers of rat skin. Changes in skin lipid prolife were observed in the rat skin on treatment with MLX-NLC gel and the results supported skin lipid extraction as a possible penetration enhancement mechanism. MLX-NLC gel demonstrated sustained pain inhibitory effect. Pharmacokinetics study established that topical application of MLX-NLC gel had the potential to avoid systemic uptake and hence the risk of systemic adverse effects. MLX-NLC gel demonstrated good skin tolerability and biosafety. Excellent physical stability of nanogel was observed at 4?±?2?°C. Significance: The study revealed that NLC gel is a promising carrier system for the topical application of MLX without side effects. PMID:25151872

Khurana, S; Jain, N K; Bedi, P M S

2014-08-25

253

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

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

254

A neural network-based method for voltage security monitoring  

Microsoft Academic Search

In this paper, a neural network-based method is proposed for monitoring the online voltage security of electric power systems. Using a dynamic model of the system, voltage stability is measured totally, considering a suitable stability index for the whole system, and locally, by defining appropriate voltage-margins for detecting the area of the system where the instability phenomenon arises. A three-layer

M. La Scala; M. Trovato; F. Torelli

1996-01-01

255

Re-evaluating the role of sterics and electronic coupling in determining the open-circuit voltage of organic solar cells.  

PubMed

The effects of sterics and molecular orientation on the open-circuit voltage and absorbance properties of charge-transfer states are explored in model bilayer organic photovoltaics. It is shown that the open-circuit voltage correlates linearly with the charge-transfer state energy and is not significantly influenced by electronic coupling. PMID:23897581

Graham, Kenneth R; Erwin, Patrick; Nordlund, Dennis; Vandewal, Koen; Li, Ruipeng; Ngongang Ndjawa, Guy O; Hoke, Eric T; Salleo, Alberto; Thompson, Mark E; McGehee, Michael D; Amassian, Aram

2013-11-13

256

Evaluation of dimensional stability and accuracy of autoclavable polyvinyl siloxane impression material.  

PubMed

Dimensionally stable autoclavable impressions will be effective in controlling the cross-infection and contamination caused by patient's saliva and other oral secretions. The accuracy of newly introduced autoclavable polyvinyl siloxane impression material was assessed for its dimensional stability and accuracy. A standard metal model (Dentoform, U-501, Columbia) was customised for impression making. The impressions were made using the newly introduced polyvinyl siloxane impression materials (AFFINIS, Coltene/Whaledent AG, 9450 Alstalten, Switzerland). Fifty impressions were made and were divided into two groups A and B of 25 each. Group A was the control sample (non-autoclaved impressions) and group B was the test sample (autoclaved impressions), which was subjected to the steam autoclave procedure at 134 °C for 18 min, casts were poured in type IV gypsum products. The customised metal model, casts obtained from control and test group were subjected to laboratory evaluation with help of a travelling microscope (×10 magnification), and digital vernier calliper (0.01 mm/10 ?m accuracy). Data analysis was done using one-way ANOVA and One-Sample t test to evaluate the overall accuracy (P < 0.005). As a result, there was an average reduction of 0.016 ?m in overall dimension between the test and the control group when compared with the master model, which is not statistically or clinically significant. The newly introduced polyvinyl siloxane impression material is accurate and dimensional stable for clinical use when steam autoclaved at 134 °C for 18 min. PMID:24431790

Reddy, Subash M; Vijitha, D; Karthikeyan, S; Balasubramanian, R; Satish, A

2013-12-01

257

Precision voltage regulator  

NASA Technical Reports Server (NTRS)

Balanced positive and negative voltage output circuit, in which error voltage for control is developed from difference in absolute value of positive and negative voltages referenced to a common point, regulates voltage for use with inertial reference unit. Fast-acting, temperature-compensated, high-gain operational amplifier circuits maintain common point.

Hand, P. J.; Crawford, R. A.

1972-01-01

258

A matter of quantum voltages  

SciTech Connect

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.

Sellner, Bernhard; Kathmann, Shawn M., E-mail: Shawn.Kathmann@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2014-11-14

259

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...

260

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...

261

A rapid method for evaluation of the oxidation stability of castor oil FAME: influence of antioxidant type and concentration  

Microsoft Academic Search

The oxidation stability of castor oil fatty methyl ester (FAME), doped with four different phenolic antioxidants, was evaluated using a rapid method of thermal and air-contact degradation. The methodology is based on the induction times observed when the samples are contacted with pure oxygen at elevated pressures and temperatures. The results indicate different performances of the antioxidants as well as

Susana V. Araújo; F. Murilo T. Luna; Estélio M. Rola Jr.; Diana C. S. Azevedo; Célio L. Cavalcante Jr.

2009-01-01

262

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

PubMed

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

Le Cann, Sophie; Galland, Alexandre; Rosa, Benoît; Le Corroller, Thomas; Pithioux, Martine; Argenson, Jean-Noël; Chabrand, Patrick; Parratte, Sébastien

2014-09-01

263

Preparation of sterically stabilized chitin nanowhisker dispersions by grafting of poly(ethylene glycol) and evaluation of their dispersion stability.  

PubMed

Sterically stabilized chitin nanowhiskers (ChNWs) were prepared by surface grafting monomethoxy poly(ethylene glycol) (mPEG) via reductive amination of primary amino groups on ChNWs and terminal aldehydes on mPEG. The amount of grafted mPEG was determined to be 0.2-0.3 g/g ChNWs, by conductometric titration, from the decrease in amino groups after grafting. ChNWs with controlled amounts of surface amino groups were obtained by deacetylation; however, this did not cause a drastic change in the amount of grafted mPEG. Grafting was confirmed by Fourier-transform infrared spectroscopy; however, X-ray diffractometry indicated no sign of mPEG. Thermogravimetry indicated a higher amount of mPEG than that from titration, suggesting an overestimation due to the facilitated combustion of grafted samples. In contrast to ungrafted samples, all grafted samples were stable in the presence of electrolytes. However, liquid-crystalline phase separation of grafted ChNWs was not observed, possibly owing to the high viscosity of the concentrated sample. PMID:25455958

Araki, Jun; Kurihara, Mari

2015-01-12

264

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

SciTech Connect

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.

Maleki, H. [Maleki Technologies, Inc. (United States); Chaturvedi, L. [Environmental Evaluation Group, Albuquerque, NM (United States)

1996-08-01

265

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

PubMed

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

Arthur, Sabastine E; Gibson, Kristen E

2015-03-01

266

Evaluation of maturity and stability parameters of composts prepared from agro-industrial wastes.  

PubMed

The objective of this study was to evaluate changes in physical, chemical and biological parameters to assess the maturity and stability of composts prepared from mixture of different farm and agro-industrial wastes over a period of 150 days. All the composts appeared granular, dark grey in color without foul odor and attained an ambient temperature at 120 days of composting indicating the stable nature of composts. Correlation analysis showed that the optimal values of the selected parameters for our experimental conditions are as follows: organic matter loss >42%, C:N ratio <15, water soluble organic carbon (C(w)):organic N (N(org)) ratio <0.55, humic acid (HA):fulvic acid (FA) ratio >1.9, humification index (HI) >30%, cation exchange capacity (CEC):total organic carbon (TOC) ratio >1.7 and germination index (GI) >70%. Compost enriched with sewage sludge, pressmud and poultry waste matured earlier compared to composts either enriched with distillery effluent or un-enriched. PMID:21075622

Raj, Dev; Antil, R S

2011-02-01

267

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

SciTech Connect

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)

Piascik, Jeffrey R.; Thompson, Jeffrey Y.; Bower, Christopher A.; Stoner, Brian R. [Curriculum of Applied and Material Science, University of North Carolina, Chapel Hill, North Carolina 27599 and RTI International, Center for Materials and Electronic Technologies, Research Triangle Park, North Carolina 27709 (United States); Curriculum of Applied and Material Science, and School of Dentistry, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); RTI International, Center for Materials and Electronic Technologies, Research Triangle Park, North Carolina 27709 (United States); RTI International, Center for Materials and Electronic Technologies, Research Triangle Park, North Carolina, 27709 and Curriculum of Applied and Material Science, University of North Carolina, Chapel Hill, North Carolina 27599 (United States)

2005-09-15

268

Voltage-gated sodium channels  

PubMed Central

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 channel’s 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

Abdelsayed, Mena; Sokolov, Stanislav

2013-01-01

269

Voltage compensation of an induction generator with long-shunt connection  

Microsoft Academic Search

Preliminary studies of voltage vs. speed relationships, stability of generated voltage, and voltage compensation of the self-excited induction generator are presented. In order to improve the voltage regulation, the long-shunt connection of the capacitors to the generator is used. The magnetizing inductance of the machine is used as a saturable reactor. The values of the capacitors for series and parallel

E. Bim; J. Szajner; Y. Burian

1989-01-01

270

Ultrasonic test application for evaluation of improvement of marl soil stabilized by lime  

NASA Astrophysics Data System (ADS)

Ultrasonic test has been accepted for non-destructive, fast, and accurate measurement of elastic constants, longitudinal and shear wave velocities, in rock and soil materials in the geotechnical engineering. The ultrasonic test is valid for the measurement of compression and shear wave velocities in the both anisotropic and isotropic samples. There is a direct relation between the elastic constants and elastic waves velocities. The velocity of elastic waves varies with the variation of compression and tensile strengths of materials. In this research, using ultrasonic velocity-meter, propagation velocity of high frequency pulses, according to ISRM (International Society for Rock Mechanics), and ASTM D2845 standards, was measured in samples from an unstable telecommunication station site located in Ahvaz city in Iran. The geological materials of the site were composed of marl soils, and the sequences of sandstone, and marlstone. The test results showed that longitudinal and shear wave velocities, Young's and shear modulus are higher in the sandstone samples obtained from the site than the marlstone samples. Some engineering tests showed that the marl soils due to high clay minerals content and high swelling potential are the cause of instability in the form of crack in the site. Chemical stabilization with lime was selected as a way for reduction of the swelling potential and enhancement of the strength characteristics of the marl soils. Several samples of the marl soils were mixed and cured with different (1, 3, 6, 9, 12, and15) percents of lime. Longitudinal wave velocity, according to the standards mentioned above, was measured in the prepared samples. The test results showed that longitudinal wave velocity increases in the samples with the increase of lime content from 1 up to 9 percent, and decreases after 9 percent lime. The uniaxial compression test results showed that the uniaxial strength value of the prepared samples increases with the increase of lime content from 1 up to 9 percent, and decreases after 9 percents. Also, other geotechnical tests showed that 9 percent lime in the marl soil samples, is the optimum content for the improvement of the marl soils in the site. With comparison of the results from these tests, it can be inferred that the ultrasonic testing can be used as a fast method for the evaluation of improvement of marl soils stabilized by lime.

Jamshidi, H.; Sheshpari, M.

2011-12-01

271

Interfacial degradation effects of aqueous solution-processed molybdenum trioxides on the stability of organic solar cells evaluated by a differential method  

NASA Astrophysics Data System (ADS)

The authors investigate the influence of two hole interfacial materials poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) and aqueous solution-processed MoO3 (sMoO3) on cell stability. sMoO3-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 sMoO3 interfacial layer compared to PEDOT:PSS by comparing their different trap states distributions.

Lou, Yan-Hui; Wang, Zhao-Kui; Yuan, Da-Xing; Okada, Hiroyuki; Liao, Liang-Sheng

2014-09-01

272

Interfacial degradation effects of aqueous solution-processed molybdenum trioxides on the stability of organic solar cells evaluated by a differential method  

SciTech Connect

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.

Lou, Yan-Hui [Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China); Graduate School of Science and Technology, University of Toyama, 3190 Gofuku Toyama (Japan); Wang, Zhao-Kui, E-mail: zkwang@suda.edu.cn, E-mail: lsliao@suda.edu.cn; Yuan, Da-Xing; Liao, Liang-Sheng, E-mail: zkwang@suda.edu.cn, E-mail: lsliao@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China); Okada, Hiroyuki [Graduate School of Science and Technology, University of Toyama, 3190 Gofuku Toyama (Japan)

2014-09-15

273

Generating Electrical Voltage  

NSDL National Science Digital Library

This interactive resource adapted from the Wisconsin Online Resource Center illustrates how electrical voltage is generated through a process called magnetic induction and describes some of the factors that affect the magnitude of the voltage produced.

WGBH Educational Foundation

2009-12-24

274

Test–retest stability on the WRAT-3 reading subtest in geriatric cognitive evaluations  

Microsoft Academic Search

The primary goal of this study was to establish the stability of the Wide Range Achievement Test (WRAT-3) Reading score across two annual assessments of aging individuals. Participants were classified as controls (n = 200), mild cognitive impairment (MCI; n = 137), or possible or probable Alzheimer's disease (AD; n = 41). Test–retest stability was acceptable to high for all

Lee Ashendorf; Angela L. Jefferson; Robert C. Green; Robert A. Stern

2009-01-01

275

Evaluation of factors affecting the solidification\\/stabilization of heavy metal sludge. Final report  

Microsoft Academic Search

Solidification\\/stabilization 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 known to inhibit the setting and strength development properties of cement and pozzolan binding agents commonly used in solidification\\/stabilization processes. This study

R. M. Bricka; L. W. Jones

1993-01-01

276

Study of second phase in bioabsorbable magnesium alloys: Phase stability evaluation via Dmol{sup 3} calculation  

SciTech Connect

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.

Yang, Huazhe [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Department of Biophysics, China Medical University, Shenyang 110001 (China); Liu, Chen [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wan, Peng; Tan, Lili; Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2013-11-01

277

Automatic voltage imbalance detector  

DOEpatents

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.

Bobbett, Ronald E. (Los Alamos, NM); McCormick, J. Byron (Los Alamos, NM); Kerwin, William J. (Tucson, AZ)

1984-01-01

278

Optimization of power systems with voltage security constraints  

NASA Astrophysics Data System (ADS)

As open access market principles are applied to power systems, significant changes in their operation and control are occurring. In the new marketplace, power systems are operating under higher loading conditions as market influences demand greater attention to operating cost versus stability margins. Since stability continues to be a basic requirement in the operation of any power system, new tools are being considered to analyze the effect of stability on the operating cost of the system, so that system stability can be incorporated into the costs of operating the system. In this thesis, new optimal power flow (OPF) formulations are proposed based on multi-objective methodologies to optimize active and reactive power dispatch while maximizing voltage security in power systems. The effects of minimizing operating costs, minimizing reactive power generation and/or maximizing voltage stability margins are analyzed. Results obtained using the proposed Voltage Stability Constrained OPF formulations are compared and analyzed to suggest possible ways of costing voltage security in power systems. When considering voltage stability margins the importance of system modeling becomes critical, since it has been demonstrated, based on bifurcation analysis, that modeling can have a significant effect of the behavior of power systems, especially at high loading levels. Therefore, this thesis also examines the effects of detailed generator models and several exponential load models. Furthermore, because of its influence on voltage stability, a Static Var Compensator model is also incorporated into the optimization problems.

Rosehart, William Daniel

279

Gemifloxacin mesylate (GFM) stability evaluation applying a validated bioassay method and in vitro cytotoxic study.  

PubMed

The validation of a microbiological assay applying the cylinder-plate method to determine the quinolone gemifloxacin mesylate (GFM) content is described. Using a strain of Staphylococcus epidermidis ATCC 12228 as the test organism, the GFM content in tablets at concentrations ranging from 0.5 to 4.5 ?g mL(-1) could be determined. A standard curve was obtained by plotting three values derived from the diameters of the growth inhibition zone. A prospective validation showed that the method developed is linear (r=0.9966), precise (repeatability and intermediate precision), accurate (100.63%), specific and robust. GFM solutions (from the drug product) exposed to direct UVA radiation (352 nm), alkaline hydrolysis, acid hydrolysis, thermal stress, hydrogen peroxide causing oxidation, and a synthetic impurity were used to evaluate the specificity of the bioassay. The bioassay and the previously validated high performance liquid chromatographic (HPLC) method were compared using Student's t test, which indicated that there was no statistically significant difference between these two validated methods. These studies demonstrate the validity of the proposed bioassay, which allows reliable quantification of GFM in tablets and can be used as a useful alternative methodology for GFM analysis in stability studies and routine quality control. The GFM reference standard (RS), photodegraded GFM RS, and synthetic impurity samples were also studied in order to determine the preliminary in vitro cytotoxicity to peripheral blood mononuclear cells. The results indicated that the GFM RS and photodegraded GFM RS were potentially more cytotoxic than the synthetic impurity under the conditions of analysis applied. PMID:21238783

Paim, Clésio S; Führ, Fernanda; Barth, Aline B; Gonçalves, Carlos E I; Nardi, Nance; Steppe, Martin; Schapoval, Elfrides E S

2011-02-15

280

High Voltage SPT Performance  

NASA Technical Reports Server (NTRS)

A 2.3 kW stationary plasma thruster designed to operate at high voltage was tested at discharge voltages between 300 and 1250 V. Discharge specific impulses between 1600 and 3700 sec were demonstrated with thrust between 40 and 145 mN. Test data indicated that discharge voltage can be optimized for maximum discharge efficiency. The optimum discharge voltage was between 500 and 700 V for the various anode mass flow rates considered. The effect of operating voltage on optimal magnet field strength was investigated. The effect of cathode flow rate on thruster efficiency was considered for an 800 V discharge.

Manzella, David; Jacobson, David; Jankovsky, Robert

2001-01-01

281

Evaluation of the positive biased temperature stress stability in HfSiON gate dielectrics  

Microsoft Academic Search

Electrical instability due to charge trapping in high-k materials is a primary concern for the usefulness of these films in future CMOS devices. This paper reports the effect of charge trapping on the threshold voltage and transistor drive current of devices made with HfSiON gate dielectric. Our results show that the physics of the charge trapping in HfSiON is unique

A. Shanware; M. R. Visokay; J. J. Chambers; A. L. P. Rotondaro; H. Bu; M. J. Bevan; R. Khamankar; S. Aur; P. E. Nicollian; J. McPherson; L. Colombo

2003-01-01

282

The production of anti-Vibrio harveyi egg yolk immunoglobulin and evaluation of its stability and neutralisation efficacy  

Microsoft Academic Search

In order to replace the antibiotic treatment for control of Vibrio harveyi, a causal agent of luminous disease in Black tiger shrimp, anti-V. harveyi IgY was produced and showed its potential in our preliminary study. However, for further use as feed additive, the IgY stability should be evaluated. The titre of specific IgY was enhanced with an immunostimulant, C-phosphate guanosine

Kawin Punyokun; Ratchanee Hongprayoon; Prapansak Srisapoome; Theerapol Sirinarumitr

2012-01-01

283

Evaluating the Effects of Environmentally Acceptable Clay Stabilizer on Bandera Sandstone  

E-print Network

screening test to qualitatively select clay stabilizing additive concentrations to be used for further tests. Coreflood experiments were done using an inorganic (Al/Zr) polymer compound at concentrations of 1, 2, and 4 wt% on Bandera sandstone core samples...

Emecheta, Akunna C

2013-08-26

284

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...

285

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...

286

Economic evaluation of flying-qualities design criteria for a transport configured with relaxed static stability  

NASA Technical Reports Server (NTRS)

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.

Sliwa, S. M.

1980-01-01

287

Compensated MultiPole Mercury Trapped Ion Frequency Standard and Stability Evaluation of Systematic Effects  

Microsoft Academic Search

We have developed a compensated multi-pole Linear Ion Trap Standard (LITS) that eliminates nearly all frequency sensitivity to residual ion number variations. When operated with 199Hg+, this trapped ion clock has recently demonstrated extremely good stability over a 9-month period. The short-term stability has been measured at 5 × 10-14\\/tau1\\/2 and an upper limit on long-term fractional frequency deviations of

E. A. Burt; S. Taghavi-Larigani; J. D. Prestage; R. L. Tjoelker

2009-01-01

288

Examination of Dynamic Drop Test Method for Evaluation of Hydrophobicity Stability of Polymeric Insulating Materials by CIGRE Round Robin Test  

NASA Astrophysics Data System (ADS)

To evaluate time variation of hydrophobicity of silicone rubbers used for outdoor polymeric insulators, various kinds of test methods have been suggested. CIGRE WG D1.14 conducted an international Round Robin Test (RRT) to clarify the efficiency and reproducibility of Dynamic Drop Test for the evaluation of hydrophobicity stability of the materials. Three Japanese universities were participated the RRT and had contributed much for the activity. This paper provides the outline of CIGRE RRT and typical experimental results of the Dynamic Drop test.

Homma, Hiroya; Nagao, Masayuki; Matsumoto, Takaie; Otsubo, Masahisa; Tokoro, Tetsuro

289

Biomechanical Evaluation of Pedicle Screw-Based Dynamic Stabilization Devices for the Lumbar Spine: A Systematic Review  

PubMed Central

Study Design This study is a systematic review of published biomechanical studies involving pedicle screw-based posterior dynamic stabilization devices (PDS) with a special focus on kinematics and load transmission through the functional spine unit (FSU). Methods A literature search was performed via the PubMed online database from 1990 to 2008 using the following key words: “biomechanics,” “lumbar dynamic stabilization,” “Graf system,” “Dynesys,” and “posterior dynamic implant.” Citations were limited to papers describing biomechanics of pedicle screw-based PDS devices currently available for clinical use. Studies describing clinical experience, radiology, and in vivo testing were excluded from the review. Parameters measured included kinematics of the FSU (range of motion (ROM), neutral zone (NZ), and location of the center of rotation) and load transmission through the disk, facets, and instrumentation. Results A total of 27 publications were found that concerned the biomechanical evaluation of lumbar pedicle screw-based dynamic stabilization instrumentation. Nine in vitro experimental studies and 4 finite element analyses satisfied the inclusion criteria. The Dynesys implant was the most investigated pedicle screw-based PDS system. In vitro cadaveric studies mainly focused on kinematics comparing ROM of intact versus instrumented spines whereas finite element analyses allowed analysis of load transmission at the instrumented and adjacent levels. Conclusion Biomechanical studies demonstrate that pedicle screw-based PDS devices limit intervertebral motion while unloading the intervertebral disk. The implant design and the surgical technique have a significant impact on the biomechanical behavior of the instrumented spinal segment. The posterior placement of such devices results in non-physiologic intervertebral kinematics with a posterior shift of the axis of rotation. Biomechanical studies suggest that the difference at the adjacent level between investigated dynamic devices and rigid stabilization systems may not be as high as reported. Finally, additional investigations of semirigid devices are needed to further evaluate their biomechanical properties compared to soft stabilization PDS systems.

Ponnappan, Ravi K.; Song, Jason; Vaccaro, Alexander R.

2008-01-01

290

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...

291

Evaluation of biological stability and corrosion potential in drinking water distribution systems: a case study.  

PubMed

The appearance of assimilable organic carbon (AOC), microbial regrowth, disinfection by-products (DBPs), and pipe corrosion in drinking water distribution systems are among those major safe drinking water issues in many countries. The water distribution system of Cheng-Ching Lake Water Treatment Plant (CCLWTP) was selected in this study to evaluate the: (1) fate and transport of AOC, DBPs [e.g., trihalomethanes (THMs), haloacetic acids (HAAs)], and other organic carbon indicators in the selected distribution system, (2) correlations between AOC (or DBPs) and major water quality parameters [e.g. dissolved oxygen (DO), free residual chlorine, and bacteria, and (3) causes and significance of corrosion problems of the water pipes in this system. In this study, seasonal water samples were collected from 13 representative locations in the distribution system for analyses of AOC, DBPs, and other water quality indicators. Results indicate that residual free chlorine concentrations in the distribution system met the drinking water standards (0.2 to 1 mg l(-1)) established by Taiwan Environmental Protection Administration (TEPA). Results show that AOC measurements correlated positively with total organic carbon (TOC) and UV-254 (an organic indicator) values in this system. Moreover, AOC concentrations at some locations were higher than the 50 microg acetate-C l(-1) standard established by Taiwan Water Company. This indicates that the microbial regrowth might be a potential water quality problem in this system. Higher DO measurements (>5.7 mg l(-1)) might cause the aerobic biodegradation of THMs and HAAs in the system, and thus, low THMs (<0.035 mg l(-1)) and HAAs (<0.019 mg l(-1)) concentrations were observed at all sampling locations. Results from the observed negative Langelier Saturation Index (LSI) values, higher Ryznar Stability Index (RSI) values, and high Fe3+ concentrations at some pipe-end locations indicate that highly oxidative and corrosive conditions occurred. This reveals that pipe replacement should be considered at these locations. These findings would be helpful in managing the water distribution system for maintaining a safe drinking water quality. PMID:18483769

Chien, C C; Kao, C M; Chen, C W; Dong, C D; Chien, H Y

2009-06-01

292

Evaluation of the physical properties, bulk density and aggregate stability of potential substrates in quarry restoration.  

NASA Astrophysics Data System (ADS)

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.

Jordan, M.; Garcia-Orenes, F.; Mataix-Solera, J.; Garcia-Sanchez, E.

2012-04-01

293

In vitro evaluation of the acetabular cup primary stability by impact analysis.  

PubMed

The implant primary stability of the acetabular cup (AC) is an important parameter for the surgical success of press-fit procedures used for the insertion of cementless hip prostheses. In previous studies by our group (Mathieu, V., Michel, A., Lachaniette, C. H. F., Poignard, A., Hernigou, P., Allain, J., and Haiat, G., 2013, "Variation of the Impact Duration During the in vitro Insertion of Acetabular Cup Implants," Med. Eng. Phys., 35(11), pp. 1558-1563) and (Michel, A., Bosc, R., Mathieu, V., Hernigou, P., and Haiat, G., 2014, "Monitoring the Press-Fit Insertion of an Acetabular Cup by Impact Measurements: Influence of Bone Abrasion," Proc. Inst. Mech. Eng., Part H, 228(10), pp. 1027-1034), the impact momentum and duration were shown to carry information on the press-fit insertion of the AC within bone tissue. The aim of the present study is to relate the impact momentum recorded during the AC insertion to the AC biomechanical primary stability. The experimental protocol consisted in testing 13 bovine bone samples that underwent successively series of 15 reproducible mass falls impacts (5 kg, 5 cm) followed by tangential stability testing. Each bone sample was tested with different hole sizes in order to obtain different stability configurations. The impact momentum and the tangential primary stability reach a maximum value for an interference fit equal to around 1 mm. Moreover, a correlation between the impact momentum and the stability was obtained with all samples and all configuration (R2?=?0.65). The implant primary stability can be assessed through the measurement of the impact force signal analysis. This study opens new paths for the development of a medical device which could be used as a decision support system to assist the surgeon during the insertion of the AC implant. PMID:25565382

Michel, Adrien; Bosc, Romain; Vayron, Romain; Haiat, Guillaume

2015-03-01

294

Improving Low Voltage Ride Through Capability of Wind Generators Using Dynamic Voltage Restorer  

NASA Astrophysics Data System (ADS)

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.

Sivasankar, Gangatharan; Suresh Kumar, Velu

2014-08-01

295

Laboratory evaluation of the pointing stability of the ASPS Vernier System  

NASA Technical Reports Server (NTRS)

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.

1980-01-01

296

Ecotoxicological evaluation of the short term effects of fresh and stabilized textile sludges before application in forest soil restoration.  

PubMed

The short term (eco)toxicity potential of fresh and stabilized textile sludges, as well as the short term (eco)toxicity of leachates obtained from both fresh and stabilized textile sludges, was evaluated by a battery of toxicity tests carried out with bacteria, algae, daphnids, fish, earthworms, and higher plants. The (eco)toxicological results showed that, after 120 d of stabilization, the experimental loading ratio of 25% sludge:75% soil (v/v) (equivalent to 64.4 ton/ha) did not significantly increase toxicity effects and increased significantly the biomass yield for earthworms and higher plants. The rank of biological sensitivity endpoints was: Algae approximately Plant biomass > Plant germination approximately Daphnids > Bacteria approximately Fish > Annelids. The lack of short term toxicity effects and the stimulant effect observed with higher plants and earthworms are good indications of the fertilizer/conditioner potential of this industrial waste, which after stabilization can be used in the restoration of a non-productive forest soil. PMID:16935397

Rosa, Edson V C; Giuradelli, Thayse M; Corrêa, Albertina X R; Rörig, Leonardo R; Schwingel, Paulo R; Resgalla, Charrid; Radetski, Claudemir M

2007-03-01

297

VOLTAGE COLLAPSE AVOIDANCE IN POWER SYSTEMS: A RECEDING HORIZON APPROACH  

Microsoft Academic Search

In this paper, a receding horizon control approach is developed for voltage stabilization in power systems. The primary focus is on a benchmark system proposed in the context of a European project. The system is termed hybrid due to the finite set of control inputs, state automata description of the voltage primary controller and their interactions with the load nonlinear

S. A. ATTIA; M. ALAMIR; C. CANUDAS DE WIT

2006-01-01

298

High Voltage Operation of Helical Pulseline Structures for Ion Acceleration  

Microsoft Academic Search

To accelerate ions using a helical pulseline requires the launching of a high voltage traveling wave with a waveform determined by the beam transport physics in order to maintain stability and acceleration. This waveform is applied to the front of the helix, creating a steep voltage ramp that moves down the helix, accelerating ions over distances much longer than the

W. L. Waldron; L. L. Reginato; R. J. Briggs

2005-01-01

299

Voltage Converter TYPICAL APPLICATION  

E-print Network

s Inverting and Doubling Modes s Minimum Open Circuit Voltage Conversion Efficiency: 99% s Typical Power Voltage RL = 1k Inverter, LV = Open q 3 5.5 V Inverter, LV = GND q 1.5 5.5 V Doubler, LV = VOUT q 2.5 5 % Voltage Conversion Efficiency No Load 99 99.96 % Oscillator Sink or Source Current Boost = Open ±1.1 µ

Berns, Hans-Gerd

300

Characterization and evaluation of the hydrolytic stability of trifluoroacetylated cellulose fibers.  

PubMed

The controlled heterogeneous modification of cellulose fibers with trifluoroacetic anhydride was investigated. The characterization of the ensuing materials was performed by elemental analysis, FTIR spectroscopy, X-ray diffraction (XRD), thermogravimetry, and surface analysis (XPS, ToF-SIMS, and contact angles measurements). The trifluoroacetylation enhanced significantly the hydrophobic and lipophobic character of the fibers, whereas their thermal stability and cristallinity were only modestly affected by this treatment, except under the most severe conditions for the latter. Their hydrolytic stability to water vapour was also assessed as a function of the air humidity and shown to be lower than that of still liquid water in the case of a saturated atmosphere. PMID:17889889

Cunha, Ana G; Freire, Carmen S R; Silvestre, Armando J D; Neto, Carlos Pascoal; Gandini, Alessandro; Orblin, Elina; Fardim, Pedro

2007-12-15

301

Voltage Oscillations in Power Distribution Networks in the Presence of DFIGs and Induction Motor Loads  

E-print Network

Voltage Oscillations in Power Distribution Networks in the Presence of DFIGs and Induction Motor, DFIG, eigenvalue, in- duction motor, small-signal stability. I. INTRODUCTION Distributed generation (DG

Pota, Himanshu Roy

302

Evaluation of thermal-oxidative stability and antiglioma activity of Zanthoxylum tingoassuiba essential oil entrapped into multi- and unilamellar liposomes.  

PubMed

Zanthoxylum tinguassuiba essential oil (ZtEO) contains ?-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

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

303

Evaluation of liquid fragility and thermal stability of Al-based metallic glasses by equivalent structure parameter  

NASA Astrophysics Data System (ADS)

Based on extended Ideal-Atomic-Packing model, we propose an equivalent structure parameter “ 6x+11y” to evaluate fragility and thermal stability of Al-TM-RE metallic glasses, where x and y are composition concentrations of transition metal (TM) and rare earth (RE), respectively. Experimental results show that glass forming compositions with “ 6x+11y” near 100 have the smallest fragility parameter and best structure stability. In addition, “ 6x+11y” parameter has a positive relationship with onset-crystallization temperature, T. Al-TM-RE glassy alloys with (6x+11y)?100 undergo primary crystallization of fcc-Al nanocrystals, while alloys with (6x+11y)>100 exhibit nanoglassy or glassy crystallization behavior.

Li, Xuelian; Bian, Xiufang; Hu, Lina

2010-08-01

304

Validation of uv derivative spectrophotometric method for determination of benazepril hydrochloride in tablets and evaluation of its stability.  

PubMed

The absorbance and first-, second- and third-order derivative UV spectroscopic methods were applied for the determination of benazepril hydrochloride (BEN) in model solutions and tablets, as well as the estimation of its stability in solid phase. Derivative UV spectroscopy and HPLC methods were tested for: precision, linearity, accuracy and repeatability. HPLC was used as a reference method. The study presents that derivative UV spectroscopy (the first and second derivative only) and HPLC can be successfully applied for the quantitative analysis of benazepril hydrochloride both pure and in pharmaceutical formulations. Although, the first and second derivative spectrophotometric methods are fast, precise and accurate, but they cannot be used for evaluation of purity and stability of BEN in pharmaceutical formulations (due to a lack of selectivity). PMID:19702164

Stanisz, Beata; Paszun, Sylwia; Le?niak, Marcin

2009-01-01

305

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...

306

Influence of Input Parameters on Dynamic Orbital Stability of Walking: In-Silico and Experimental Evaluation  

PubMed Central

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

Riva, Federico; Bisi, Maria Cristina; Stagni, Rita

2013-01-01

307

An Outcome Evaluation of an Inpatient Crisis Stabilization and Assessment Program for Youth  

ERIC Educational Resources Information Center

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…

Greenham, Stephanie L.; Bisnaire, Lise

2008-01-01

308

The Evaluation of Strain and Stabilization in Molecules Using Isodesmic Reactions.  

ERIC Educational Resources Information Center

Isodesmic reactions are hypothetical chemical changes in which the number of bonds of a given type are retained but change in relation to one another. Discusses use of these reactions and reaction energy to measure deviations from additivity of bond energy. Also considers relationship of enthalpies to strain and resonance stability. (JM)

Fuchs, Richard

1984-01-01

309

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...

310

Quantitative evaluation of transient heat transfer on axial flow compressor stability  

Microsoft Academic Search

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

R. A. Crawford; A. E. Burwell

1985-01-01

311

Relationships between analytical methods utilized as tools in the evaluation of landfill waste stability  

Microsoft Academic Search

In this study, the refuse from 12 landfills of various ages ranging from fresh refuse to material 11 years old was collected, and changes in the bio-stability parameters were determined. The parameters measured included cellulose, lignin, biochemical methane potential (BMP) and volatile solids, along with plastics. These parameters, along with the cellulose to lignin ratio were compared to determine which

Ryan J. Kelly; Bradley D. Shearer; Jongmin Kim; C. Douglas Goldsmith; Gary R. Hater; John T. Novak

2006-01-01

312

Safety evaluation for the interim stabilization of Tank 241-C-103  

SciTech Connect

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.

Geschke, G.R.

1995-03-01

313

Off-set stabilizer for comparator output  

DOEpatents

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.

Lunsford, James S. (Los Alamos, NM)

1991-01-01

314

Evaluation on the stability of Hg in ABS disk CRM during measurements by wavelength dispersive X-ray fluorescence spectrometry.  

PubMed

The stability of Hg in an acrylonitrile-butadiene-styrene disk certified reference material (ABS disk CRM, NMIJ CRM 8116-a) during measurements by wavelength dispersion X-ray fluorescence (WD-XRF) analysis was evaluated in this study. The XRF intensities of Hg (L(?)) and Pb (L(?)) as well as the XRF intensity ratios of Hg (L(?))/Pb (L(?)) observed under different X-ray tube current conditions as well as their irradiation time were examined to evaluate the stability of Hg in the ABS disk CRM. The observed XRF intensities and the XRF intensity ratios for up to 32 h of measurements under 80 mA of X-ray tube current condition were constant, even though the surface of the ABS disk CRM was charred by the X-ray irradiation with high current for a long time. Moreover, the measurements on Hg and Pb in the charred disks by an energy dispersive XRF (ED-XRF) spectrometer showed constant XRF intensity ratios of Hg (L(?))/Pb (L(?)). From these results, Hg in the ABS disk CRM was evaluated to be sufficiently stable for XRF analysis. PMID:23149612

Ohata, Masaki; Kidokoro, Toshihiro; Hioki, Akiharu

2012-01-01

315

Cascaded voltage collapse  

SciTech Connect

The dynamic phenomena of voltage collapse are analyzed by the method of dynamic simulation using induction motor models. From the view point of dynamic phenomena, the voltage collapse starts locally at the weakest node and spreads out to the other weak nodes.

Sekine, Y. (Tokyo Univ. (Japan)); Ohtsuki, H. (Kansai Electric Power Co., Inc., Osaka (Japan))

1990-02-01

316

Voltage verification unit  

DOEpatents

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.

Martin, Edward J. (Virginia Beach, VA)

2008-01-15

317

Relationship between voltage instability and multiple load flow solutions in electric power systems  

SciTech Connect

There have been observed several voltage instability phenomena in electric power systems where receiving end voltages oscillate remarkably or get much lower than the nominal values. Those phenomena tend to occur in heavy loaded conditions and seem to be related to the multiple load flow solution problem for the following reasons. It has been confirmed analytically and by simulations that the multiple load flow solutions are likely to appear under the heavy-loaded conditions, and that the individual solutions of the solution pair have different features from each other, from the standpoint of stability, although they are close to each other. It is hard to solve the voltage instability problem at a stretch since dynamic factors get involved in this problem and thus a high dimentional and multi-parameter system has to be dealt with. It may be wise to analyze, first of all, static and/or semidynamic performances of this problem, which could be approached more or less systematically. Next, the relationship between the dynamic factors and voltage instability will be analyzed and evaluated. Following the way of thinking above, this paper proposes a sequence of criteria which are applied to the individual members of a solution pair of the load flow to see their difference in behavior. The relationship between the voltage instability and closely-located solution pair is analyzed from various viewpoints for power systems of different types and sizes.

Tamura, Y.; Iwamoto, S.; Mori, H.

1983-05-01

318

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)

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.

Mukhopadhyay, V.; Newsom, J. R.

1982-01-01

319

Cranial cruciate ligament rupture in large and giant dogs. A retrospective evaluation of a modified lateral extracapsular stabilization.  

PubMed

Forty-two dogs weighing between 30 and 87 kg (mean body weight of 49 kg) with cranial cruciate ligament ruptures (CCLR) were treated with a modified lateral extra-capsular stabilization using braided polyester prosthetic ligament-suture anchor technique. Clinical and radiographic outcomes of 48 stifles were retrospectively evaluated with a mean follow-up of 18 months. Ten dogs had pulled out their bone anchors with no clinical relevance. Draining tracts did not appear. Despite mild radiographic progression of osteoarthritis, all of the dogs regained acceptable function of the operated limb. PMID:17364096

Guénégo, L; Zahra, A; Madelénat, A; Gautier, R; Marcellin-Little, D J; Hulse, D

2007-01-01

320

Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain Area Nevada Nuclear Waste Site Investigation (NNWSI)  

SciTech Connect

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.

NONE

1995-09-30

321

Correlation and evaluation of inplane stability characteristics for an advanced bearingless main rotor  

NASA Technical Reports Server (NTRS)

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.

Weller, W. H.

1983-01-01

322

Preclinical evaluation of efficacy and stability of docetaxel micelle-encapsulated by a tripodal cyclotriphosphazene amphiphile.  

PubMed

Docetaxel formulated by micelle-encapsulation using a tripodal cyclotriphosphazene amphiphile [NP(MPEG750)(GlyPheLeu)2Et]3 (CP750) was named "Phostaxel" and compared in efficacy and stability with Taxotere(®) formulated using the surfactant polysorbate 80, which is currently in clinical use. Phostaxel has always shown better efficacy than Taxotere(®) in various xenograft trials at the same dosage and administration schedule against the tumor cell lines tested. The better efficacy of Phostaxel could be explained based on the difference in pharmacokinetic and biodistribution profiles of Phostaxel and Taxotere(®). Phostaxel exhibited significantly slower clearance rate and larger AUClast value compared with Taxotere(®). Phostaxel has also shown higher DTX distribution in tumor than Taxotere(®). In addition, Phostaxel displayed better solution stability compared with Taxotere(®) both in distilled water and in saline solution at room and refrigerator temperatures. PMID:24930885

Chae, Song Wha; Jun, Yong Joo; Cui, Jin Xin; Park, Jung Hyun; Lee, Hwa Jeong; Sohn, Youn Soo

2014-06-01

323

Compensated Multi-Pole Mercury Trapped Ion Frequency Standard and Stability Evaluation of Systematic Effects  

NASA Astrophysics Data System (ADS)

We have developed a compensated multi-pole Linear Ion Trap Standard (LITS) that eliminates nearly all frequency sensitivity to residual ion number variations. When operated with 199Hg+, this trapped ion clock has recently demonstrated extremely good stability over a 9-month period. The short-term stability has been measured at 5 × 10-14/?1/2 and an upper limit on long-term fractional frequency deviations of < 2.7 × 10-17/day was measured in comparison to the laser-cooled primary standards and to the post-processed ultra-stable version of TAI known as TTBIPM using GPS carrier phase time transfer. We have also made a first measurement of the Hg+/Hg collision shift and place a limit of +3.8(7.2) × 10-8/Pa on the shift constant.

Burt, E. A.; Taghavi-Larigani, S.; Prestage, J. D.; Tjoelker, R. L.

2009-04-01

324

Evaluation of H2RG stability for infrared Earth-observing systems  

NASA Astrophysics Data System (ADS)

Although originally developed for astronomical applications, the space qualification and availability of the Teledyne HAWAII detector make it appealing for high-precision Earth-observing systems such as the carbon monoxide correlation radiometer required for GEO-CAPE. In this shot noise-limited application, the signal-to-noise ratio of a co-averaged measurement is driven by the detector's temporal stability. To assess the stability, we operated the H2RG under monitored blackbody illumination. The Teledyne SIDECAR ASIC provided 16-bit digitization and clocking for integration times faster than the frame conversion time. With proper application of reference signals, the co-averaging of hundreds of frames is possible. Integrations of one-quarter of the full well depth can attain precision to the 200 ppm level in the co-averaged result. For integrations above three-quarters the well depth, the precision reaches 111 ppm.

Sullivan, P. W.; Edens, W. K.; Darlington, E. H.; Neil, D. O.

2011-10-01

325

Analysis of NSTX TF Joint Voltage Measurements  

SciTech Connect

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''.

R, Woolley

2005-10-07

326

Electrical safety for high voltage arrays  

NASA Technical Reports Server (NTRS)

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.

Marshall, N. A.

1983-01-01

327

Impaction grafted bone chip size effect on initial stability in an acetabular model: Mechanical evaluation  

PubMed Central

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; 2–4 mm3, 10 mm3 or 20 mm3 bone chip size for impaction grafting reconstruction. The models underwent compression loading up to 9500 N and displacement within the acetabular model was measured indicating the initial mechanical stability. Results This study reveals that, although not statistically significant, the largest (20 mm3) bone chip size grafted models have an inferior maximum stiffness compared to the medium (10 mm3) bone chip size. Interpretations Our study suggests that 10 mm3 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

Holton, Colin; Bobak, Peter; Wilcox, Ruth; Jin, Zhongmin

2013-01-01

328

Evaluation of emulsifier stability of biosurfactant produced by Saccharomyces lipolytica CCT0913  

Microsoft Academic Search

Surface-active compounds of biological origin are w idely used for many industries (cosmetic, food, pet rochemical). The Saccharomyces lipolytica CCT-0913 was able to grow and produce a biosurfact ant on 5% (v\\/v) diesel-oil at pH 5.0 and 32 o C. The cell-free broth emulsified and stabilized th e oil-in-water emulsion through a first order kinet ics. The results showed that

Álvaro Silva Lima; Ranulfo Monte Alegre

2009-01-01

329

Performance evaluation of cement stabilized fly ash-GBFS mixes as a highway construction material.  

PubMed

Fly ash and granulated blast furnace slag (GBFS) are major by-products of thermal and steel plants, respectively. These materials often cause disposal problems and environmental pollution. Detailed laboratory investigations were carried out on cement stabilized fly ash-(GBFS) mixes in order to find out its suitability for road embankments, and for base and sub-base courses of highway pavements. Proctor compaction test, unconfined compressive strength (UCS) test and California Bearing Ratio (CBR) test were conducted on cement stabilized fly ash-GBFS mixes as per the Indian Standard Code of Practice. Cement content in the mix was varied from 0% to 8% at 2% intervals, whereas the slag content was varied as 0%, 10%, 20%, 30% and 40%. Test results show that an increase of either cement or GBFS content in the mixture, results in increase of maximum dry density (MDD) and decrease of optimum moisture content (OMC) of the compacted mixture. The MDD of the cement stabilized fly ash-GBFS mixture is comparably lower than that of similarly graded natural inorganic soil of sand to silt size. This is advantageous in constructing lightweight embankments over soft, compressible soils. An increase in percentage of cement in the fly ash-GBFS mix increases enormously the CBR value. Also an increase of the amount of GBFS in the fly ash sample with fixed cement content improves the CBR value of the stabilized mix. In the present study, the maximum CBR value of compacted fly ash-GBFS-cement (52:40:8) mixture obtained was 105%, indicating its suitability for use in base and sub-base courses in highway pavements with proper combinations of raw materials. PMID:18060762

Singh, S P; Tripathy, D P; Ranjith, P G

2008-01-01

330

Freeze-dried whole plasma: Evaluating sucrose, trehalose, sorbitol, mannitol and glycine as stabilizers  

Microsoft Academic Search

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

Irina Bakaltcheva; Anne Marie O'Sullivan; Peter Hmel; Helen Ogbu

2007-01-01

331

Evaluation of quinupristin\\/dalfopristin (Synercid®) and RPR 106?972 stability in susceptibility testing media  

Microsoft Academic Search

In response to conflicting reports on the chemical stability of quinupristin\\/dalfopristin, a study was designed to assess the in vitro longevity and effects of media and storage conditions on this streptogramin combination. Broth microdilution trays containing parenteral (quinupristin\\/dalfopristin) and oral (RPR 106?972) streptogramin combinations as well as pristinomycin components (P-I and P-II) were preincubated at 35°C for 12–72 h before

Steven A. Marshall; Kari C. Kugler; Ronald N. Jones

2000-01-01

332

Evaluation of Metabolically Stabilized Angiotensin IV Analogs as Procognitive/Antidementia Agents  

PubMed Central

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

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

333

Thermal stability evaluation of microstructures and mechanical properties of tungsten vanadium alloys  

NASA Astrophysics Data System (ADS)

The thermal stability is important for tungsten based alloys as plasma facing materials to survive against high heat flux in fusion reactors. In this work, the thermal stability of W-5%V alloy fabricated following a powder metallurgy route by spark plasma sintering technique has been studied. To investigate the impact of temperature on the mechanical properties and microstructures, the alloy was subjected to heat treatment for 2 h over the temperature range 900-1500°C in a pure argon furnace. The micro-hardness values of the heat treated alloys were highly stable as compared to pure tungsten. A slight decrease flexural strength was observed with increasing annealing temperature. The maximum change flexural strength at the highest treated temperature was noted about 14% lower. The morphology analyses of the crack surfaces by scanning electron microscopy did not identify a drastic change in tungsten grain size, after heat treatment. The results indicate that the addition of vanadium in tungsten improves the overall thermal stability of microstructures and mechanical properties.

Arshad, Kameel; Zhao, Ming-Yue; Yuan, Yue; Zhang, Ying; Zhou, Zhang-Jian; Lu, Guang-Hong

2014-10-01

334

Iron hydroxy carbonate formation in zerovalent iron permeable reactive barriers: Characterization and evaluation of phase stability  

SciTech Connect

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.

Wilkin, Richard T.; Lee, T.R. (U.S. EPA)

2010-10-22

335

Evaluation of plasma membrane stability by detergent-induced rupture of osmotically swollen sperm.  

PubMed

A general assay for plasma membrane stability was developed and tested. Osmotically swollen spermatozoa were ruptured with detergents and their volume distribution was monitored with resistance pulse spectroscopy. The extent of cell breakage was determined and expressed as [D]50, the concentration of detergent necessary to lyse 50% of the initially intact cells. Preliminary experiments established the degree to which spermatozoa could be swollen without lysis (no detergent) and the ability of the method to detect known mixtures of intact and membrane disrupted spermatozoa. [D]50 values were determined for caput (immature) and cauda (mature) ram epididymal spermatozoa with four detergents (cetyltrimethylammonium bromide, sodium dodecylsulfate, Zwittergent 3-14, and sodium deoxycholate). [D]50 values for caput spermatozoa were higher than those for cauda spermatozoa (P less than 0.05) for all detergents but cetyltrimethylammonium bromide. These changes are consistent with a qualitative model of membrane structure and stability based on lipid shape and composition and with the compositional changes known to occur during epididymal maturation. Additional studies using rooster spermatozoa established that a typical cryopreservation protocol leaves the surviving spermatozoa with membranes with greater sensitivity to detergent-induced stress. Since osmotic swelling has been microscopically localized to the tail plasma membrane, the changes in membrane stability can be assigned specifically to that region. PMID:1560184

Schweisguth, D C; Hammerstedt, R H

1992-03-01

336

Iron hydroxy carbonate formation in zerovalent iron permeable reactive barriers: Characterization and evaluation of phase stability  

NASA Astrophysics Data System (ADS)

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 (? fG°) 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.

Lee, Tony R.; Wilkin, Richard T.

2010-07-01

337

Utilization of phosphogypsum in tannery sludge stabilization and evaluation of the radiological impact.  

PubMed

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

Pantazopoulou, E; Zebiliadou, O; Noli, F; Mitrakas, M; Samaras, P; Zouboulis, A

2015-03-01

338

Optimization of microwave-assisted extraction of cottonseed oil and evaluation of its oxidative stability and physicochemical properties.  

PubMed

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

Taghvaei, Mostafa; Jafari, Seid Mahdi; Assadpoor, Elham; Nowrouzieh, Shahram; Alishah, Omran

2014-10-01

339

An in vitro and in vivo toxicologic evaluation of a stabilized aloe vera gel supplement drink in mice.  

PubMed

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

Sehgal, Inder; Winters, Wallace D; Scott, Michael; Kousoulas, Konstantine

2013-05-01

340

Application of maltodextrin and gum Arabic in microencapsulation of saffron petal's anthocyanins and evaluating their storage stability and color.  

PubMed

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

Mahdavee Khazaei, K; Jafari, S M; Ghorbani, M; Hemmati Kakhki, A

2014-05-25

341

Single Event Transients in Low Voltage Dropout (LVDO) Voltage Regulators  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the use of Low Voltage Dropout (LVDO) Voltage Regulators in environments where heavy ion induced Single Event Transients are a concern to the designers.Included in the presentation are results of tests of voltage regulators.

LaBel, K.; Karsh, J.; Pursley, S.; Kleyner, I.; Katz, R.; Poivey, C.; Kim, H.; Seidleck, C.

2006-01-01

342

Low voltage to high voltage level shifter and related methods  

NASA Technical Reports Server (NTRS)

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.

Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

2006-01-01

343

Voltage-Dependent Gating of hERG Potassium Channels  

PubMed Central

The mechanisms by which voltage-gated channels sense changes in membrane voltage and energetically couple this with opening of the ion conducting pore has been the source of significant interest. In voltage-gated potassium (Kv) channels, much of our knowledge in this area comes from Shaker-type channels, for which voltage-dependent gating is quite rapid. In these channels, activation and deactivation are associated with rapid reconfiguration of the voltage-sensing domain unit that is electromechanically coupled, via the S4–S5 linker helix, to the rate-limiting opening of an intracellular pore gate. However, fast voltage-dependent gating kinetics are not typical of all Kv channels, such as Kv11.1 (human ether-à-go-go related gene, hERG), which activates and deactivates very slowly. Compared to Shaker channels, our understanding of the mechanisms underlying slow hERG gating is much poorer. Here, we present a comparative review of the structure–function relationships underlying activation and deactivation gating in Shaker and hERG channels, with a focus on the roles of the voltage-sensing domain and the S4–S5 linker that couples voltage sensor movements to the pore. Measurements of gating current kinetics and fluorimetric analysis of voltage sensor movement are consistent with models suggesting that the hERG activation pathway contains a voltage independent step, which limits voltage sensor transitions. Constraints upon hERG voltage sensor movement may result from loose packing of the S4 helices and additional intra-voltage sensor counter-charge interactions. More recent data suggest that key amino acid differences in the hERG voltage-sensing unit and S4–S5 linker, relative to fast activating Shaker-type Kv channels, may also contribute to the increased stability of the resting state of the voltage sensor. PMID:22586397

Cheng, Yen May; Claydon, Tom W.

2012-01-01

344

Homogeneity and stability of materials distributed within the wageningen evaluating programmes for analytical laboratories  

Microsoft Academic Search

Participation in laboratory evaluating programmes (Proficiency Testing schemes) is becoming increasingly important, especially for accredited laboratories. The Wageningen Agricultural University meets this need by organizing several world?wide international laboratory evaluating programmes on chemical analysis of soils (ISE), plants OPE), manure, refuses (MARSEP) and sediments (SETOC). Since 1995, the existing programmes have been placed under an umbrella organization called WEPAL: Wageningen

D. van Dijk; V. J. G. Houba

2000-01-01

345

Development of Multi-Functional Voltage Restore System  

NASA Astrophysics Data System (ADS)

Recently, with the dawn of the electric deregulation, the installation of distributed generation with power electronics device has grown. This current causes a greater concern of power quality, primarily voltage disturbance for power companies, and their interest in power quality is peaking. Utilities are also interested in keeping their customers satisfied, as well as keeping them on-line and creating more revenue for the utility. As a countermeasure against the above surroundings, a variety type of devices based on power electronics has been developed to protect customers' load from power line voltage disturbance. One of them is the series type voltage restore. The series device is an active device, designed to provide a pure sinusoidal load voltage at all times, correcting voltage disturbance. Series type device compensates for voltage anomalies by inserting the ‘missing’ voltage onto the line through insertion transformer and inverter. This paper shows the setting guideline of target level to compensate voltage disturbance, that is, voltage dip, voltage harmonics, voltage imbalance and voltage flicker, and the design approach of the prototype of series voltage restores to accomplish the required compensation level. The prototype system gives satisfactory compensation performance through evaluation tests, which confirm the validity and effectiveness of the system.

Suzuki, Satoshi; Ueda, Yoshinobu; Koganezawa, Takehisa; Ogihara, Yoshinori; Mori, Kenjiro; Fukazu, Naoaki

346

Voltage balanced multilevel voltage source converter system  

SciTech Connect

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.

Peng, F.Z.; Lai, J.S.

1997-07-01

347

Voltage balanced multilevel voltage source converter system  

DOEpatents

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.

Peng, Fang Zheng (Oak Ridge, TN); Lai, Jih-Sheng (Knoxville, TN)

1997-01-01

348

Evaluation of microwave oven heating for prediction of drug-excipient compatibilities and accelerated stability studies.  

PubMed

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 150°C and 180°C as compared to accelerated stability studies performed at 40°C and 80°C using a conventional oven. Ranking of the reactivity of the excipients could be made in the DoE studies performed at 150-180°C, which was representative for the ranking obtained after storage at 40°C and 80°C. 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

Schou-Pedersen, Anne Marie V; Østergaard, Jesper; Cornett, Claus; Hansen, Steen Honoré

2015-05-15

349

Photoacoustic Evaluation of Sunscreen Stability: Wind, Water, and the Influence of the Substrates  

NASA Astrophysics Data System (ADS)

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).

Pinto, S. B.; Barja, P. R.

2012-11-01

350

Evaluation of Reinforcement and Analysis of Stability of a High-Arch Dam Based on Geomechanical Model Testing  

NASA Astrophysics Data System (ADS)

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.

Zhang, L.; Liu, Y. R.; Yang, Q.

2015-03-01

351

Organic solar cells: evaluation of the stability of P3HT using time-delayed degradation  

NASA Astrophysics Data System (ADS)

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.

Poh, Chung-How; Poh, Chung-Kiak; Bryant, Glenn; Belcher, Warwick; Dastoor, Paul

2011-12-01

352

Generating Electrical Voltage  

NSDL National Science Digital Library

Teachers' Domain presents this interactive lesson designed to help students "learn how a generator converts mechanical energy into electrical energy. Investigate the principle of magnetic induction by moving a conductor through a magnetic field to see how voltage is generated." The lesson is divided into three major sections: How Do Generators Work?, What Factors Influence Voltage Strength?, and What Determines Voltage Polarity? There are plenty of animations to help students visualize the processes at work in electricity generation. On the site, visitors will also find a supplemental background essay, discussion questions, and standards alignment from Teachers' Domain.

353

VOLTAGE SECURITY ENHANCEMENT AND CONGESTION MANAGEMENT VIA STATCOM & IPFC USING ARTIFICIAL INTELLIGENCE  

Microsoft Academic Search

Voltage security and congestion management are crucial issues in power systems, especially under heavily loaded conditions. In the new scheme of electricity restructuring, voltage security problems become even more serious. Due to the increase in stability margins, FACTS devices are the best option to mitigate voltage instability by reactive power management. The main purpose of this paper is to identify

A. KARAMI; M. RASHIDINEJAD; A. A. GHARAVEISI

2007-01-01

354

Evaluation of Solvita compost stability and maturity tests for assessment of quality of end-products from mixed latrine style compost toilets  

SciTech Connect

Highlights: • Solvita® stability and maturity tests used on composting toilet end-product. • Solvita® ammonia better suited in evaluation of feedstock suitability for vermicomposting. • No clear value of Solvita® stability test due to prevalent inhibition of decomposition by ammonia. - Abstract: It is challenging and expensive to monitor and test decentralized composting toilet systems, yet critical to prevent the mismanagement of potentially harmful and pathogenic end-product. Recent studies indicate that mixed latrine composting toilets can be inhibited by high ammonia content, a product of urea hydrolysis. Urine-diverting vermicomposting toilets are better able to accomplish the goals of remote site human waste management by facilitating the consumption of fecal matter by earthworms, which are highly sensitive to ammonia. The reliability of Solvita® compost stability and maturity tests were evaluated as a means of determining feedstock suitability for vermicomposting (ammonia) and end-product stability/completeness (carbon dioxide). A significant linear regression between Solvita® ammonia and free ammonia gas was found. Solvita® ranking of maturity did not correspond to ranking assigned by ammonium:nitrate standards. Solvita® ammonia values 4 and 5 contained ammonia levels below earthworm toxicity limits in 80% and 100% of samples respectively indicative of their use in evaluating feedstock suitability for vermicomposting. Solvita® stability tests did not correlate with carbon dioxide evolution tests nor ranking of stability by the same test, presumably due to in situ inhibition of decomposition and microbial respiration by ammonia which were reported by the Solvita® CO{sub 2} test as having high stability values.

Hill, Geoffrey B., E-mail: geoff.hill@geog.ubc.ca [University of British Columbia, Department of Geography, 1984 West Mall, Vancouver, Canada V6T 1Z2 (Canada); Baldwin, Susan A. [Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, B.C., Canada V6T 1Z3 (Canada); Vinnerås, Bjorn [Swedish University of Agricultural Sciences, Box 7032, SE-750 07 Uppsala (Sweden)

2013-07-15

355

High voltage DC power supply  

DOEpatents

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.

Droege, T.F.

1989-12-19

356

High voltage DC power supply  

DOEpatents

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.

Droege, Thomas F. (Batavia, IL)

1989-01-01

357

Cryopreservation of Quercus suber somatic embryos by encapsulation-dehydration and evaluation of genetic stability.  

PubMed

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

Fernandes, Pedro; Rodriguez, Eleazar; Pinto, Glória; Roldán-Ruiz, Isabel; De Loose, Marc; Santos, Conceição

2008-12-01

358

Biomechanical evaluation of Caspar cervical screws: comparative stability under cyclical loading.  

PubMed

Anterior cervical instrumentation is used as an adjunct to bone fusion; however, definitive biomechanical data to support some applications and techniques are lacking. In the absence of supportive experimental data, posterior cortical penetration has been recommended with the Caspar system. Previously, we compared the axial pull-out strength of Caspar screws with and without posterior cortical penetration. This study compares the stability of unicortical versus bicortical screw penetration groups under cyclical loading simulating physiological flexion-extension. Caspar screws were placed in human cadaveric vertebrae with or without posterior cortical purchase. Each screw was separately tested, simulating flexion-extension to 200 cycles. Deformation time data allowed a direct comparison of screw "wobble" with and without posterior cortical purchase. The mean deformation differences between subcortical and bicortical groups were statistically significant and increased over time within both groups. Enhanced stability was noted with bicortical purchase throughout most of the examined range, becoming more pronounced over longer periods of cyclical loading. Significant (P < 0.05) increases in deformation over time were noted for both groups, suggesting potentially significant deterioration at the screw-bone interface, despite bicortical purchase. Such deterioration with repeated flexion-extension loading may be of concern in the use of Caspar plates in the presence of multicolumn instability. PMID:8133990

Gallagher, M R; Maiman, D J; Reinartz, J; Pintar, F; Yoganandan, N

1993-12-01

359

Critical evaluation of the unsteady aerodynamics approach to dynamic stability at high angles of attack  

NASA Technical Reports Server (NTRS)

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.

Hui, W. H.

1985-01-01

360

Analysis and test evaluation of the dynamic response and stability of three advanced turboprop models  

NASA Technical Reports Server (NTRS)

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.

Bansal, P. N.; Arseneaux, P. J.; Smith, A. F.; Turnberg, J. E.; Brooks, B. M.

1985-01-01

361

High voltage power supply  

NASA Technical Reports Server (NTRS)

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.

Ruitberg, A. P.; Young, K. M. (inventors)

1985-01-01

362

High Voltage Solar Array  

NASA Astrophysics Data System (ADS)

In order to manage gigantic power of SSPS (Space Solar Power System) efficiently, use of extreme high voltage is necessary unless we minimize the transmission distance by employing a sandwich type of generator/transmitter panel. For 1 GW-class SSPS, the power transmission/generation voltage of 10 kV is necessary to keep the cable mass below a few hundred tons. To realize high voltage photovoltaic power generation, arcing caused by environmental interaction must be overcome. Three issues are reviewed. The first is degradation of solar cell performance due to repetitive arcing resulted from surface charging in GEO. The second is sustained arc phenomenon that may lead to catastrophic loss of significant portion of the total power. The third is micrometeoroid or space debris impact and resulting sustained arc. A design of high voltage solar array is proposed to prevent solar cell degradation due to repeated trigger arcs and sustained arc.

Cho, Mengu

363

Improving membrane voltage measurements  

E-print Network

as fluorescence resonance energy transfer (FRET) donor and acceptor to develop a voltage sensor, named Mermaid activities in cultured excitable cells. Notably, Mermaid has fast on-off kinetics at warm (B33 1C

Cai, Long

364

Understanding Skill in EVA Mass Handling. Volume 4; An Integrated Methodology for Evaluating Space Suit Mobility and Stability  

NASA Technical Reports Server (NTRS)

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.

McDonald, P. Vernon; Newman, Dava

1999-01-01

365

Josephson voltage standards  

Microsoft Academic Search

This paper reviews the present state of modern Josephson voltage standards. The presentation focuses on conventional dc standards based on underdamped superconductor-insulator-superconductor junctions and programmable standards based on overdamped superconductor-insulator-normal conductor-insulator-superconductor junctions. The current developments of ac standards on the basis of pulse-driven arrays and single flux quantum-based voltage multipliers are briefly summarized.

Johannes Kohlmann; Ralf Behr; Torsten Funck

2003-01-01

366

Release profile and stability evaluation of optimized chitosan/alginate nanoparticles as EGFR antisense vector  

PubMed Central

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

Azizi, Ebrahim; Namazi, Alireza; Haririan, Ismaeil; Fouladdel, Shamileh; Khoshayand, Mohammad R; Shotorbani, Parisa Y; Nomani, Alireza; Gazori, Taraneh

2010-01-01

367

Study on process development and property evaluation of sol-gel derived magnesia stabilized zirconia minispheres  

NASA Astrophysics Data System (ADS)

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.

Judes, J.; Kamaraj, V.

2014-06-01

368

Transdermal microemulsions of Glycyrrhiza glabra L.: characterization, stability and evaluation of antioxidant potential.  

PubMed

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

Mostafa, Dina M; Ammar, Nagwa M; Abd El-Alim, Sameh H; El-anssary, Amira A

2014-03-01

369

Biological kinetics evaluation of anaerobic stabilization pond treatment of palm oil mill effluent.  

PubMed

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

Wong, Yee Shian; Kadir, Mohd Omar A B; Teng, Tjoon Tow

2009-11-01

370

Phase stability and biological property evaluation of plasma sprayed hydroxyapatite coatings for orthopedic and dental applications.  

PubMed

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 110mm working distance from the nozzle showed an average Ca ion release of 18 and 90ppm in neutral and acidic environments, respectively. Decreasing the working distance to 90mm resulted in the formation of a coating with less crystalline HA and phases with higher solubility products, and consequently higher dissolution over 32days. 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 ?-helix content. Osteoid formation was found on Sr-HA implants as early as 7weeks post implantation compared to HA coated and uncoated Ti implants. After 12weeks 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 16weeks 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

Vahabzadeh, Sahar; Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

2015-04-15

371

Long-term Stability of Total RNA in RNAstable(®) as Evaluated by Expression Microarray.  

PubMed

Storage of labile RNA in laboratories is accomplished through ultra-low freezing of the nucleic acids. This however requires expensive freezers, convenient storage, reliable electrical power, and increased shipping costs, thereby making it a less viable option. Biomatrica (San Diego, CA) has created RNAstable(®), a stabilization reagent that is used to store RNA in a dehydrated state at room temperature (RT) and protects the RNA from degradation. Our objective was to investigate the sequence integrity and suitability of RNA when stored in RNAstable at extended time periods and at varying temperatures through use of Illumina and Agilent RNA expression microarrays. We observed in Bioanalyzer electropherograms that total RNA extracted from 293 cells stored at RT in RNAstable for 4.5 and 11.5 months is similar in quality to RNA stored at -80°C. Illumina mRNA expression array QC metrics and gene expression patterns from RNAstable-protected RNA, in contrast to RNA stored without RNAstable, correlated well with those of freezer controls. Significantly, when RNA was stored in RNAstable at 45°C for 4.5 months, equivalent to 22 months RT storage, RNA quality, microarray probe signal intensities, probe detection rates, and expression profiles remained similar between RNAstable-protected RNA at RT and the -80°C controls. At 10.5 months, miRNA levels were compared among the storage conditions using miRNA expression arrays. Here too we found strong concordance between miRNA expression patterns when total RNA was stored in RNAstable or at -80°C. Further, Bioanalyzer electrophoresis of RNAstable-protected samples stored at RT for a relative total of 33 months or 50.5 months showed comparable integrity scores to those of -80°C controls. We conclude that use of RNAstable holds promise as an effective stabilization reagent for total RNA and should be useful in situations where shipping and storage options are limited resources. PMID:25826008

Stevenson, Holly S; Wang, Yonghong; Muller, Rolf; Edelman, Daniel C

2015-04-01

372

Importance of repeller voltage on ion current generation in an arc ion source  

Microsoft Academic Search

Summary form only given. In an earlier study, we evaluated the importance of varying the magnetic field profile in the ELS source (Vandenberg et al., 1998). Here, we study the influence of the repeller voltage. A floating repeller will acquire a steady-state voltage close to the cathode voltage. A more careful investigation shows that the floating voltage depends on the

B. H. Vanderberg; T. N. Horsky

1999-01-01

373

Fiber-optic voltage measuring system  

NASA Astrophysics Data System (ADS)

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.

Ye, Miaoyuan; Nie, De-Xin; Li, Yan; Peng, Yu; Lin, Qi-Qing; Wang, Jing-Gang

1993-09-01

374

Device for monitoring cell voltage  

DOEpatents

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.

Doepke, Matthias (Garbsen, DE); Eisermann, Henning (Edermissen, DE)

2012-08-21

375

Evaluation of the Stability, Bioavailability, and Hypersensitivity of the Omega-3 Derived Anti-Leukemic Prostaglandin: ?12-Prostaglandin J3  

PubMed Central

Previous studies have demonstrated the ability of an eicosapentaenoic acid (EPA)-derived endogenous cyclopentenone prostaglandin (CyPG) metabolite, ?12-PGJ3, to selectively target leukemic stem cells, but not the normal hematopoietic stems cells, in in vitro and in vivo models of chronic myelogenous leukemia (CML). Here we evaluated the stability, bioavailability, and hypersensitivity of ?12-PGJ3. The stability of ?12-PGJ3 was evaluated under simulated conditions using artificial gastric and intestinal juice. The bioavailability of ?12-PGJ3 in systemic circulation was demonstrated upon intraperitoneal injection into mice by LC-MS/MS. ?12-PGJ3 being a downstream metabolite of PGD3 was tested in vitro using primary mouse bone marrow-derived mast cells (BMMCs) and in vivo mouse models for airway hypersensitivity. ZK118182, a synthetic PG analog with potent PGD2 receptor (DP)-agonist activity and a drug candidate in current clinical trials, was used for toxicological comparison. ?12-PGJ3 was relatively more stable in simulated gastric juice than in simulated intestinal juice that followed first-order kinetics of degradation. Intraperitoneal injection into mice revealed that ?12-PGJ3 was bioavailable and well absorbed into systemic circulation with a Cmax of 263 µg/L at 12 h. Treatment of BMMCs with ZK118182 for 12 h resulted in increased production of histamine, while ?12-PGJ3 did not induce degranulation in BMMCs nor increase histamine. In addition, in vivo testing for hypersensitivity in mice showed that ZK118182 induces higher airways hyperresponsiveness when compared ?12-PGJ3 and/or PBS control. Based on the stability studies, our data indicates that intraperitoneal route of administration of ?12-PGJ3 was favorable than oral administration to achieve effective pharmacological levels in the plasma against leukemia. ?12-PGJ3 failed to increase histamine and IL-4 in BMMCs, which is in agreement with reduced airway hyperresponsiveness in mice. In summary, our studies suggest ?12-PGJ3 to be a promising bioactive metabolite for further evaluation as a potential drug candidate for treating CML. PMID:24312486

Kudva, Avinash K.; Kaushal, Naveen; Mohinta, Sonia; Kennett, Mary J.; August, Avery; Paulson, Robert F.; Prabhu, K. Sandeep

2013-01-01

376

Evaluation of functional stability and batch-to-batch reproducibility of a Castanea sativa leaf extract with antioxidant activity.  

PubMed

A growing body of evidence suggests that free radicals are generated by UV irradiation being responsible for skin injury. In this regard, the topical use of formulations composed of plant extracts with antioxidant activity could represent a useful strategy for the prevention of photoaging and oxidative-stress-mediated diseases. The aim of this study was to assess the reproducibility of the extraction method and the functional stability of a Castanea sativa leaf extract in view of its application as topical antioxidant. Measurements of 1,1-diphenyl-2-picryl hydrazyl (DPPH) scavenging activity, total phenols (measured by the Folin Ciocalteu assay) and phenolic composition (high-performance liquid chromatography unit coupled to a UV detector) were carried out on three different batches. The influence of pH and temperature on the extract's DPPH scavenging activity was assessed in aqueous and glyceric solutions (0.025% w/v) over a 3-month period. Minor differences were found between the three extract batches for all the evaluated parameters, and therefore the reproducibility of the extraction method can be inferred. pH presented a great influence in the extract functional stability. Major antioxidant activity decrease was found at pH 7.1, while lower changes were observed at pH 5. Glyceric solutions were stable throughout the test period. At 40 degrees C and pH 5, a marked decrease of activity was observed. Again, glyceric solutions were the most stable, even at 40 degrees C. Proper selection of pH and solvent is mandatory to ensure the stability of the studied extract after being incorporated in semisolid forms. In view of these results, glycerine is proposed as the best vehicle for topical formulations incorporating C. sativa leaf extract, which should have a pH around 5. PMID:20066522

Almeida, Isabel F; Costa, Paulo C; Bahia, M Fernanda

2010-03-01

377

Evaluation of Disulfide Bond Position to Enhance the Thermal Stability of a Highly Stable Single Domain Antibody  

PubMed Central

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

Zabetakis, Dan; Olson, Mark A.; Anderson, George P.; Legler, Patricia M.; Goldman, Ellen R.

2014-01-01

378

Evaluation of the Low-Speed Stability and Control Characteristics of a Mach 5.5 Waverider Concept  

NASA Technical Reports Server (NTRS)

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.

Hahne, David E.

1997-01-01

379

Assessment of gait stability, harmony, and symmetry in subjects with lower-limb amputation evaluated by trunk accelerations.  

PubMed

Analysis of upper-body accelerations is a promising and simple technique for quantitatively assessing some general features of gait such as stability, harmony, and symmetry. Despite the growing literature on elderly healthy populations and neurological patients, few studies have used accelerometry to investigate these features in subjects with lower-limb amputation. We enrolled four groups of subjects: subjects with transfemoral amputation who walked with a locked knee prosthesis, subjects with transfemoral amputation who walked with an unlocked knee prosthesis, subjects with transtibial amputation, and age-matched nondisabled subjects. We found statistically significant differences for stability (p < 0.001), harmony (p < 0.001), and symmetry (p < 0.001) of walking, with general trends following the noted order of subjects, but with the lowest laterolateral harmony in subjects with transtibial amputation. This study is the first to investigate upper-body acceleration of subjects with unilateral lower-limb amputation during walking who were evaluated upon dismissal from a rehabilitation hospital; it is also the first study to differentiate the sample in terms of level of amputation and type of prosthesis used. PMID:25144175

Iosa, Marco; Paradisi, Francesco; Brunelli, Stefano; Delussu, Anna Sofia; Pellegrini, Roberto; Zenardi, Daniele; Paolucci, Stefano; Traballesi, Marco

2014-01-01

380

Evaluation of systemic exposure of nanoparticle suspensions subcutaneously administered to mice regarding stabilization, volume, location, concentration and size.  

PubMed

Different routes of administration are likely to result in very different outcomes due to different availability or plasma profile. The objective of the present study was to evaluate the pharmacokinetic profile after different subcutaneous (s.c.) administration of nanoparticle suspensions of a lipophilic compound to mice. Pharmacokinetics of the selected test compound and the effect of drug concentration, particle size, location of administration, volume given and particle stabilizers were studied. Adding PEGylated lipids or pluronic F-127 to the negatively charged surface of the nanoparticles increased the stability of the particles and the bioavailability. The in vivo studies demonstrated linear absorption kinetics for the selected model compound up to at least 500?µmol/kg. Absorption from upper-neck resulted in different systemic exposure compared to administration in the hip. The former was preferred if a prolonged Cmax was desired while the latter ensured a flat profile for approximately 24 hours. Administering the double volume (but the same dose) had no effect on the pharmacokinetics, whereas smaller particle size significantly increased the exposure. PMID:23879245

Sigfridsson, Kalle; Palmer, Malin

2014-10-01

381

Novel SiL evaluation of an optimal H? controller on the stability of a MAV in flight simulator  

NASA Astrophysics Data System (ADS)

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.

Sampaio, Rafael C. B.; Becker, Marcelo; Siqueira, Adriano A. G.; Freschi, Leonardo W.; Montanher, Marcelo P.

382

Epoxidized Soybean Oil: Evaluation of Oxidative Stabilization and Metal Quenching/Heat Transfer Performance  

NASA Astrophysics Data System (ADS)

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.

Simencio Otero, Rosa L.; Canale, Lauralice C. F.; Said Schicchi, Diego; Agaliotis, Eliana; Totten, George E.; Sánchez Sarmiento, Gustavo

2013-07-01

383

Evaluation of sensory acceptability and storage stability of frozen carrot based dessert.  

PubMed

In the present study a recipe for frozen carrot based dessert (carrot halwa) was standardized on the basis of sensory characteristics such as appearance, odor, texture, taste and overall acceptability (OAA). The product was developed without addition of pure ghee to improve the storage stability under frozen conditions (-20 °C). Sensory properties of the developed product (OAA score?=?8.60) were found to be equally good as compared to the conventional carrot halwa (OAA score?=?8.75) which was prepared using pure ghee. From the physico-chemical analysis the developed product was found to have lower amount of fat (ca. 12%) than the conventional one. During the frozen storage, microbial growth in the product was found to be non-significant (P?>?0.05). The free fatty acid content, peroxide value and thiobarbituric acid content increased during frozen storage of 15 months. But the increase was insignificant. Loss in total carotenoids content of the product was found to be 60.5% from initial value at the end of 15 months frozen storage. PMID:24876657

Saxena, Tanushree Maity; Raju, P S; Bawa, A S

2014-06-01

384

Evaluation of the geological relationships to gas hydrate formation and stability  

SciTech Connect

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.

Krason, J.; Finley, P.

1988-01-01

385

Evaluation of the Effect of Ultraviolet Disinfection on Dimensional Stability of the Polyvinyl Silioxane Impressions.” an in-Vitro Study  

PubMed Central

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

Godbole, Surekha R; Dahane, Trupti M; Nimonkar, Sharayu V

2014-01-01

386

CSER 00-003 Criticality Safety Evaluation report for PFP Magnesium Hydroxide Precipitation Process for Plutonium Stabilization Glovebox 3  

SciTech Connect

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.

LAN, J.S.

2000-07-13

387

Evaluation of the Temperature Stability of a Low-Frequency a0 Mode Transducer Developed for Shm Applications  

NASA Astrophysics Data System (ADS)

A piezoelectric-based transducer generating high purity A0 mode guided waves at low frequencies (around 20 kHz) was developed. Parametric studies were undertaken by varying the backing mass length, the transducer diameter and the thickness of a soft front layer. Results obtained by FEM were validated by experimental measurements and showed that signals with A0/S0 energy ratios substantially above 40 dB can be obtained. The amplitude, phase and frequency stability of signals produced by these transducers and the general robustness of an experimental pitch-catch system were evaluated in an environment subjected to 10 °C temperature shifts. Temperature compensation and baseline subtraction methods were applied to the signals and residual signal amplitude of -38 dB in relation to the amplitude of the first arrival was obtained. Reflections from a weak reflector attached to the plate were identifiable even with a 10 °C temperate change.

Clarke, T.; Simonetti, F.; Rokhlin, S.; Cawley, P.

2008-02-01

388

A wind-tunnel evaluation of analytical techniques for predicting static stability and control characteristics of flexible aircraft  

NASA Technical Reports Server (NTRS)

An experimental evaluation of analytical techniques for predicting certain stability and control characteristics of a large flexible aircraft is presented. Analytical methods based on both the model approach and flexibility influence coefficients are developed to predict the aerodynamic characteristics of a flexible airplane. These methods are then applied to a flexibly scaled model of a supersonic transport configuration. Comparisons of wind-tunnel data, calculations based on the model approach, and flexibility influence coefficients are presented over the Mach number range from 0.6 to 2.7. An examination of the results obtained from this study indicates that both analytical techniques predict reasonably well the effect of flexibility on the basic longitudinal characteristics and that both techniques give generally comparable results.

Abel, I.

1972-01-01

389

Evaluation of biological stability and corrosion potential in drinking water distribution systems: a case study  

Microsoft Academic Search

The appearance of assimilable organic carbon (AOC), microbial regrowth, disinfection by-products (DBPs), and pipe corrosion\\u000a in drinking water distribution systems are among those major safe drinking water issues in many countries. The water distribution\\u000a system of Cheng-Ching Lake Water Treatment Plant (CCLWTP) was selected in this study to evaluate the: (1) fate and transport\\u000a of AOC, DBPs [e.g., trihalomethanes (THMs),

C. C. Chien; C. M. Kao; C. W. Chen; C. D. Dong; H. Y. Chien

2009-01-01

390

TiF(4) varnish-A (19)F-NMR stability study and enamel reactivity evaluation.  

PubMed

The aim of this study was to develop a titanium tetrafluoride (TiF(4)) varnish and evaluate the stability of the formulation and its reactivity with dental enamel. The varnish was prepared in a resinous matrix using ethanol 96% as solvent. Samples (n=45) were aged at 65 degrees C and 30% of relativity humidity (RE n degrees 01/05-ANVISA) and after 3, 6, 9 and 12 months, nine samples were removed for evaluation and compared with fresh samples. Chemical stability of TiF(4) varnish was determinate by (19)F-NMR and the reactivity of the formulation was quantified by formation of fluoride loosely (CaF(2)) and firmly bound (fluorapatite; FA) to enamel. For reactivity comparisons, a varnish without TiF(4) was used as control. The loss of soluble fluoride was about 0.9% after one year of storage. The values of the reactivity (mean+/-S.D.) of fresh, aged at 3, 6, 9 and 12 months and control samples were: CaF(2) (microg F/mm(2)): 89.3+/-27.5(a); 54.5+/-14.3(b); 51.2+/-29.8(b); 69.3+/-21.3(a); 48.0+/-27.4(b); 0.10+/-0.07(c), FA (microg F/g): 2477.5+/-1044.0(a); 2484.8+/-992.0(a); 2580.0+/-1383.9(a); 2517.2+/-929.9(a); 2121.0+/-1059.2(a); 330.0+/-180.0(b), respectively. Means followed by distinct letters were statistically different (p<0.05). After one year of storage, the formulation was chemically stable and the levels of FA were maintained. However there was an initial decrease in the ability to form CaF(2). PMID:18175996

Nóbrega, Carolina Bezerra Cavalcanti; Fujiwara, Fred Yukio; Cury, Jaime Aparecido; Rosalen, Pedro Luiz

2008-01-01

391

An evaluation of prediction accuracy and stability of a new vegetation index for estimating vegetation leaf area index  

NASA Astrophysics Data System (ADS)

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.

Jiang, Hailing; Zhang, Lifu; Yang, Hang; Chen, Xiaoping; Wang, Shudong; Li, Xueke; Liu, Kai

2014-11-01

392

Evaluation of the BD Vacutainer® RST blood collection tube for routine chemistry analytes: clinical significance of differences and stability study  

PubMed Central

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

Kocijancic, Marija; Cargonja, Jelena; Delic-Knezevic, Alma

2014-01-01

393

Evaluating the Stability of Open Bite Treatments and Its Predictive Factors in the Retention Phase during Permanent Dentition  

PubMed Central

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 18±2.1 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 -0.46±0.7 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.

Salehi, Parisa; Pakshir, Hamid Reza; Hoseini, Seyed Ali Reza

2015-01-01

394

Current vs. Voltage Feedback Amplifiers  

E-print Network

is a voltage source that is controlled by the potential difference between the two input terminals voltage to zero, hence the term voltage feedback. Gain Bandwidth Product Refer to the non-inverting gainCurrent vs. Voltage Feedback Amplifiers One question continuously troubles the analog design engi

Lanterman, Aaron

395

High voltage variable diameter insulator  

DOEpatents

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.

Vanacek, D.L.; Pike, C.D.

1982-07-13

396

Power System Online Stability Assessment using Synchrophasor Data Mining  

E-print Network

Figure 23 PMU measured voltage magnitude at the Jojoba Station (JOA): from 9:29:00 to 9:39:00 .................................................................................. 66 Figure 24 Voltage stability index calculated using the 10-minute...

Zheng, Ce

2013-04-30

397

Synthesis of saxitoxin derivatives bearing guanidine and urea groups at C13 and evaluation of their inhibitory activity on voltage-gated sodium channels.  

PubMed

Here, we describe the synthesis of the first C13-N-substituted STX derivatives 4, 5, and 6 bearing a guanidine, a urea group, and an acetamide, respectively, via the fully protected saxitoxinol derivative 8. These compounds are of interest because a previous docking study of saxitoxin (STX) with voltage-gated sodium channels (NaVCh) suggested that the C13 carbamoyl group of STX interacts with residue E403 in the pore region of NaVCh. In a cell-based assay with Neuro-2a cells, the NaVCh-inhibitory activities of 4 and 5 were more than 20- to 50-fold weaker than that of decarbamoyl-STX (3), which is 10-fold less potent than STX. On the other hand, 6 was 1000 times less potent than 3. The electrostatic analysis of C13 in STX and its analogs 4-6 using EON calculations suggested that the NaVCh-inhibitory activity of these derivatives is influenced by both the hydrophilicity and the charge balance of the substituent at C13. PMID:23989458

Akimoto, Takafumi; Masuda, Asako; Yotsu-Yamashita, Mari; Hirokawa, Takatsugu; Nagasawa, Kazuo

2013-10-14

398

Evaluation of MegaVoltage Cone Beam CT image quality with an unmodified Elekta Precise Linac and EPID: a feasibility study.  

PubMed

In order to increase the accuracy of patient positioning for complex radiotherapy treatments various 3D imaging techniques have been developed. MegaVoltage Cone Beam CT (MVCBCT) can utilise existing hardware to implement a 3D imaging modality to aid patient positioning. MVCBCT has been investigated using an unmodified Elekta Precise Linac and iView amorphous silicon electronic portal imaging device (EPID). Two methods of delivery and acquisition have been investigated for imaging an anthropomorphic head phantom and quality assurance phantom. Phantom projections were successfully acquired and CT datasets reconstructed using both acquisition methods. Bone, tissue and air were clearly resolvable in both phantoms even with low dose (22 MU) scans. The feasibility of MVCBCT was investigated using a standard linac, amorphous silicon EPID and a combination of a free open source reconstruction toolkit as well as custom in-house software written in Matlab. The resultant image quality has been assessed and presented. Although bone, tissue and air were resolvable in all scans, artifacts are present and scan doses are increased when compared with standard portal imaging. The feasibility of MVCBCT with unmodified Elekta Precise Linac and EPID has been considered as well as the identification of possible areas for future development in artifact correction techniques to further improve image quality. PMID:24609762

Markwell, Tim; Perera, Lakshal; Trapp, Jamie; Fielding, Andrew

2014-06-01

399

Numerical analysis for the evaluation of the stability of underground cavities in calcarenite interacting with buildings  

NASA Astrophysics Data System (ADS)

Soft and highly porous rocks such as tuffs and calcarenites are very common rocks. Due to their porous calcareous structure they are quite prone to water induced weathering mechanisms. Onshore and inland natural underground cavities are evident signs of these phenomena and of the effects in terms of failure. These materials have been largely employed in the past as building and ornamental stones and as sites to excavate underground cavities for different uses. The world famous Unesco site of "Sassi di Matera", the underground cavities in Canosa di Puglia and Gravina di Puglia , or the calcarenite cliff and natural caves of Polignano a Mare are the most representative cases. Nowadays, many of these are deteriorating because of weathering due to humidity, water infiltration, environmental pollution, and direct exposure to marine aerosols and meteoric water precipitations. In all these cases, a careful assessment of the safety of the built environment and a conscious identification of the safety measures cannot be separated from the analysis of the interaction between the cavities and the overlying buildings, and of the evolution and spatial distribution of the weathering processes. This contribute summarizes the authors' experience on the subject and suggests a methodological approach to quantitatively assess the stability of underground cavities. Starting from experimental evidences at micro and macroscale, the main debonding mechanisms have been taken into account in numerical models. The time-evolution scenarios of the weathering processes is introduced in three-dimensional numerical modelling. The intention is to provide a potentially useful tool for risk assessment in similar complex geomechanical situations.

Castellanza, Riccardo; Lollino, Piernicola; Oryem Ciantia, Matteo; di Prisco, Claudio; Crosta, Giovanni; Frigerio, Gabriele

2013-04-01

400

Self micro-emulsifying drug delivery system of tacrolimus: Formulation, in vitro evaluation and stability studies  

PubMed Central

Background: Tacrolimus has poor solubility in water ranging from 4 to 12 ?g/mL. The oral bio availabilities of tacrolimus is poor and exhibits high intra and inter-subject variability (4-89%, average 25%) in the liver and the kidney transplant recipients and in patients with renal impairment. Aim: The present study deals with the development and characterization of self-micro-emulsifying drug delivery system to improve the oral bioavailability of poorly soluble drug tacrolimus. Materials and Methods: Solubility of the tacrolimus was estimated in various oils, surfactants, and co-surfactants. Various in vitro tests such as percentage transmittance, emulsification time, cloud point, precipitation, and thermodynamic stabilities were used to find out optimized formulations. Optimized liquid self micro-emulsifying (SMEDDS) were characterized by particle size analysis and converted in solid by using the Florite RE as an adsorbent, which is further characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and particle size analysis. Results: The optimized liquid SMEDDS formulation contained 10% Lauroglycol FCC as an oil, 60% Cremophor RH, and 30% PEG (polyethylene glycol) 400 as a surfactant and co-surfactant respectively. The optimized liquid and solid SMEDDS showed higher drug release than the marketed capsule and pure API (active pharmaceutical ingredient) powder. For optimized liquid SMEDDS and solid SMEDDS, the globule sizes were found 113 nm and 209 nm respectively. The solid state characterization of solid-SMEDDS by SEM, DSC, FTIR, and XRD revealed the absence of crystalline tacrolimus in the solid-SMEDDS. Shelf-lives for liquid SMEDDS and solid SMEDDS were found to be 1.84 and 2.25 year respectively. Conclusions: The results indicate that liquid SMEDDS and solid SMEDDS of tacrolimus, owing to nano-sized, have potential to enhance the absorption of the drug. PMID:24015381

Patel, Pranav V; Patel, Hitesh K; Panchal, Shital S; Mehta, Tejal A

2013-01-01

401

High voltage coaxial switch  

DOEpatents

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.

Rink, John P. (Los Alamos, NM)

1983-07-19

402

High voltage coaxial switch  

DOEpatents

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.

Rink, J.P.

1983-07-19

403

Electron launching voltage monitor  

DOEpatents

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.

Mendel, C.W.; Savage, M.E.

1992-03-17

404

Lets Rock the Boat: Evaluating the Concept of Stability in Fluid Mechanics  

NSDL National Science Digital Library

As an upper level civil engineering course, Fluid Mechanics, often presents concepts that are unfamiliar to engineering students, at least to the level of understanding expected in the course. Many of these fundamentals concepts are critical to success in the course, but are frequently difficult to visualize simply with figures and equations. Additionally, many laboratory exercises for students involve a cookbook type approach which increases the chance of the attainment of reliable results, but inhibits curiosity and decreases the development of an independent engineering formation of ideas associated with problem solving. A possible solution to both issues is the incorporation of in class activities which illustrate fundamental concepts, engage students in an active learning environment, and allow for the students themselves to create a testing program. The complication lies in determining a suitable topic and in creating an activity broad enough to allow for creative testing development but narrow enough to insure at least a marginal level of reliable results. The topic chosen by the authors was that of stability, one of the basic fundamental concepts in fluid mechanics. Working in groups of four to five students, the class was asked to develop an independent testing program that addressed the qualitative effects of adjusting weight in any one, or a combination of multiple, different directions (i.e. adjustments in the x, y, and / or z plane) on a floating object. Students were given supplies to create a model barge: a Styrofoam brick, cardboard sticks, modeling clay and containers sufficiently large to allow for floatation and movement when the barge was placed inside. No restrictions were placed on the direction in which the brick was to be placed in the water, the number and location of masts, or the number, magnitude and location of weight(s). Students were told the activity was to be summarized in a one-page paper, including testing procedure, results, and conclusions and were allowed thirty minutes for experimental setup, testing, and clean-up. Determination of student comprehension was assessed through both the summary paper, as well as an exam question. Results showed a high level of understanding, both in the short term, as concluded with the paper outcomes, as well as long term retention, validated with testing results. Quantitative analysis can easily be incorporated into the program by providing measuring instruments (rulers, calipers, and a balance) if a more robust study is desired.

Bondehagen, Diane

405

Organic field-effect transistors: solution-processable, low-voltage, and high-performance monolayer field-effect transistors with aqueous stability and high sensitivity (adv. Mater. 12/2015).  

PubMed

Low-voltage, low-cost, high-performance monolayer field-effect transistors (MFETs) that comprise a densely packed, long-range ordered monolayer, spin-coated from core-cladding liquid-crystalline pentathiophenes, and a solution-processed high-k HfO2 -based nanoscale gate dielectric are reported by X. Guo and co-workers on page 2113. These MFETs are light-sensitive and are able to function as reporters to convert analyte binding events into electrical signals with ultrahigh sensitivity (ca. 10 ppb). PMID:25800630

Chen, Hongliang; Dong, Shaohua; Bai, Meilin; Cheng, Nongyi; Wang, Hao; Li, Mingliang; Du, Huiwen; Hu, Shuxin; Yang, Yanlian; Yang, Tieying; Zhang, Fan; Gu, Lin; Meng, Sheng; Hou, Shimin; Guo, Xuefeng

2015-03-01

406

LDEF Space Plasma-High Voltage Drainage Experiment post-flight results  

NASA Technical Reports Server (NTRS)

The Space Plasma-High Voltage Drainage Experiment (SP-HVDE) was comprised of two identical experimental trays. With one tray located on the leading (ram facing, B10) edge and the other located on the trailing (wake facing, D4) edge of the Long Duration Exposure Facility (LDEF), it was possible to directly compare the effects of ram and wake spacecraft environments on charged dielectric materials. Six arrays of Kapton dielectric samples of 2 mil, 3 mil, and 5 mil thicknesses maintained at +/- 300, +/- 500, and +/- 1000 voltage bias formed the experimental matrix of each tray. In addition, each tray carried two solar cell strings, one biased at +300 volts and the other at -300 volts, to study current leakage from High Voltage Solar Arrays (HVSA). The SP-HVDE provides the first direct, long-term, in-flight measurements of average leakage current through dielectric materials under electric stress. The experiment also yields information on the long term stability of the bulk dielectric properties of such materials. Data and findings of the SP-HVDE are an extension of those from shorter term flight experiments such as the PIX-1 (Plasma Interaction Experiment) and PIX-2 and are therefore valuable in the design and evaluation of long-lived space systems with high voltage systems exposed to the low earth orbital environment. A summary of the SP-HVDE post flight analysis final report delivered to the LDEF Project Office under contract to the National Aeronautics and Space Administration is presented.

Yaung, J. Y.; Blakkolb, B. K.; Wong, W. C.; Ryan, L. E.; Schurig, H. J.; Taylor, W. W. L.

1993-01-01

407

Evaluating the potential of natural curcumin for oxidative stability of soybean oil.  

PubMed

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 (25°C and 55°C) 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 25°C 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

Eshghi, Naeeme; Asnaashari, Maryam; Khodaparast, Mohammad Hossein Haddad; Hosseini, Fereshteh

2014-01-01

408

Slope stability susceptibility evaluation parameter (SSEP) rating scheme - An approach for landslide hazard zonation  

NASA Astrophysics Data System (ADS)

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.

Raghuvanshi, Tarun Kumar; Ibrahim, Jemal; Ayalew, Dereje

2014-11-01

409

Voltage-Controlled Oscillator  

NASA Technical Reports Server (NTRS)

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.

1995-01-01

410

Insulators for high voltages  

Microsoft Academic Search

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

Looms; J. S. T

1987-01-01

411

Geomagnetism and Induced Voltage  

ERIC Educational Resources Information Center

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…

Abdul-Razzaq, W.; Biller, R. D.

2010-01-01

412

Evaluation of structure and material properties of RF magnetron sputter-deposited yttria-stabilized zirconia thin films  

NASA Astrophysics Data System (ADS)

Over the past several decades, research has focused on utilizing ceramic materials in new technological applications. Their uses have been primarily in applications that involve high temperatures or corrosive environments. Unfortunately, ceramic materials have been limited especially since they can be brittle, failing in a sudden and catastrophic manner. A strong emphasis on understanding mechanical properties of ceramics and ways to improving their strength and toughness, has led to many new technologies. The present work is part of a larger research initiative that is aimed at using RF magnetron sputter deposition of yttria-stabilized zirconia to improve the fracture toughness of brittle substrates (more specifically dental ceramics). Partially-stabilized zirconia (PSZ) has been studied extensively, due to its high temperature stability and stress-induced tetragonal to monoclinic (T?M) martensitic phase transformation. RF magnetron sputtering was chosen as the deposition method because of its versatility, especially the ability to deposit oxides at low temperatures. Initial investigations focused on the development of process-structure-properties of YSZ sputtered deposited thin films. The YSZ thin films were deposited over a range of temperatures (22--300°C), pressures (5--25 mTorr), and gas compositions (Ar:O2 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°C, 75% relative humidity) led to large increase (˜ 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). Based on the above results, it was determined to evaluate stress as a function of substrate bias. It was shown that increasing substrate bias power disrupted columnar grain growth and reduced the percent change in compressive stress when exposed to ambient environments. TEM confirmed a reduction in inter-granular porosity for substrate bias depositions, but an increase in lateral defects. It was hypothesized that substrate bias would increase the film's density, but after inspection of SEM and TEM micrographs, it appeared that as bias was increased the density decreased. This T?M phase transformation has been well documented for bulk PSZ, but limited data exists for PSZ thin films. Data is presented that supports a stress-induced T=>M transformation mechanism that occurs during sputter-deposition in the presence of a substrate bias. Substrate bias (0--50W) was originally applied to increase film density, modify microstructure, and vary film stress. The films were deposited using rf magnetron sputtering from a sintered yttria-stabilized zirconia (YSZ) target and subsequently characterized using scanning (SEM) and transmission electron microscopy (TEM), x-ray diffraction (XRD), and wafer bow measurement (for stress analysis). With no substrate bias the films exhibited a columnar grain structure consistent with sputter-deposited films, with a majority tetragonal phase as determined by XRD. Under higher substrate bias, wafer bow measurements indicated a steady increase in compressive stress as substrate bias increased (max. 310MPa at 50W bias), while XRD indicated a corresponding increase in the percentage of monoclinic phase. Both SEM and TEM analyses revealed a shift from a defect-free columnar structure to one consisting of lateral intra-c

Piascik, Jeffrey Robert

413

Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion  

NASA Technical Reports Server (NTRS)

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.

Jacobson, Nathan S.; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

414

Evaluation of homogeneity and genetic stability of REOLYSIN (pelareorep) by complete genome sequencing of reovirus after large scale production.  

PubMed

REOLYSIN (pelareorep) is a proprietary isolate of the reovirus T3D (Type 3 Dearing) strain which is currently being tested in clinical trials as an anticancer therapeutic agent. Reovirus genomes are composed of ten segments of double-stranded ribonucleic acid (RNA) characterized by genome size: large (L1, L2, and L3), medium (M1, M2, and M3), and small (S1, S2, S3, and S4). The objective of this work was to evaluate the homogeneity and genetic stability of REOLYSIN. Sanger sequencing (SS) performed on test articles derived from the Master Virus Bank (MVB) and Working Virus Bank (WVB) identified many modifications when compared to GenBank reference sequences. Massively parallel sequencing (MPS) using Roche-454 sequencing was performed on REOLYSIN (100 L scale) and resulted in 69,821,115 bases and an average of 335 bases per read. Twenty-nine high confidence differences relative to the GenBank reference sequence were identified in REOLYSIN by MPS. Of those, 27 were previously identified by SS in the virus bank-derived test articles. Of the remaining two nucleotide differences, one was predicted to be silent at the amino acid level (L3 genome-T3163C, codon 1054, 86% of the population was "T" and 13% of the population were reported as "C"). The other modification was in the noncoding region (M1 genome-A2284A to A2284G), and A2284G was present in 97% of the population. The results obtained from MPS were comparable to those from SS; both demonstrate a high level of homogeneity at the amino acid level and genetic stability of REOLYSIN. Finally, phylogenetic analysis of the REOLYSIN L1 genome segment showed close evolutionary relationship with its human homologs, serotypes Lang and Dearing. PMID:24419798

Chakrabarty, Romit; Tran, Hue; Fortin, Yves; Yu, Zhenbao; Shen, Shi-Hsiang; Kolman, John; Onions, David; Voyer, Robert; Hagerman, Allison; Serl, Sarah; Kamen, Amine; Thompson, Brad; Coffey, Matt

2014-02-01

415

Development of Automatic Voltage Regulator for Low Voltage Distribution Systems  

NASA Astrophysics Data System (ADS)

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.

Matsuda, Katsuhiro; Horikoshi, Kazuhiro; Seto, Toshiyuki; Iyama, Osamu; Kobayashi, Hiromu

416

High Temperature Stability of Potassium Beta Alumina  

NASA Technical Reports Server (NTRS)

None. From Objectives section: Evaluate the stability of potassium beta alumina under potassium AMTEC operating conditions. Evaluate the stability regime in which potassium beta alumina can be fabricated.

Williams, R. M.; Kisor, A.; Ryan, M. A.

1996-01-01

417

Structural mechanism of voltage-dependent gating in an isolated voltage-sensing domain.  

PubMed

The transduction of transmembrane electric fields into protein motion has an essential role in the generation and propagation of cellular signals. Voltage-sensing domains (VSDs) carry out these functions through reorientations of positive charges in the S4 helix. Here, we determined crystal structures of the Ciona intestinalis VSD (Ci-VSD) in putatively active and resting conformations. S4 undergoes an ~5-Å displacement along its main axis, accompanied by an ~60° rotation. This movement is stabilized by an exchange in countercharge partners in helices S1 and S3 that generates an estimated net charge transfer of ~1 eo. Gating charges move relative to a ''hydrophobic gasket' that electrically divides intra- and extracellular compartments. EPR spectroscopy confirms the limited nature of S4 movement in a membrane environment. These results provide an explicit mechanism for voltage sensing and set the basis for electromechanical coupling in voltage-dependent enzymes and ion channels. PMID:24487958

Li, Qufei; Wanderling, Sherry; Paduch, Marcin; Medovoy, David; Singharoy, Abhishek; McGreevy, Ryan; Villalba-Galea, Carlos A; Hulse, Raymond E; Roux, Benoît; Schulten, Klaus; Kossiakoff, Anthony; Perozo, Eduardo

2014-03-01

418

TECHNOLOGY EVALUATION REPORT, SITE PROGRAM DEMONSTRATION OF THE INTERNATIONAL WASTE TECHNOLOGIES IN SITU STABILIZATION/-SOLIDIFICATION TECHNOLOGY, HIALEAH, FL, VOLUME II  

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...

419

Microprocessor voltage control of inverter fed asynchronous motors  

Microsoft Academic Search

The torque control of an asynchronous motor fed by a voltage source inverter (VSI) is performed by evaluating, by means of a microprocessor, in each sampling interval the voltage space vector which gives rise to a mean value of the electromagnetic torque just equal to the imposed one. The correspondent modulation technique for the VSI is described. The results obtained

C. Attaianese; A. Perfetto

1993-01-01

420

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy  

E-print Network

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the highvoltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequencycomb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Krieger, A; Catherall, R; Hochschulz, F; Krämer, J; Neugart, R; Rosendahl, S; Schipper, J; Siesling, E; Weinheimer, Ch; Yordanov, D T; Nörtershäuser, W; 10.1016/j.nima.2010.12.145

2011-01-01

421

SQUID voltage - controlled - oscillator  

SciTech Connect

The authors have investigated the SQUID as a voltage-controlled source of microwaves. The low impedance ''resistive'' SQUID can be a relatively high power (about nW), tunable, and monochromatic source for both on-chip and off-chip applications. Studies of the time-dependent junction phase and the available power spectra as they vary with such device parameters as loaded Q and the SQUID-BETA=2..pi..Li /SUB c/ //phi/ /SUB o/ establish design rules for a well-behaved oscillator. For a VCO BETA Q<2; for BETA Qgreater than or equal to2 degenerate parametric subharmonic oscillations and chaotic instabilities are observed. Power increase is suggested by the use of voltage-clamped dc SQUIDs and arrays.

Silver, A.; Sandell, R.; Wilcox, J.

1983-05-01

422

Increased voltage photovoltaic cell  

NASA Technical Reports Server (NTRS)

A photovoltaic cell, such as a solar cell, is provided which has a higher output voltage than prior cells. The improved cell includes a substrate of doped silicon, a first layer of silicon disposed on the substrate and having opposite doping, and a second layer of silicon carbide disposed on the first layer. The silicon carbide preferably has the same type of doping as the first layer.

Ross, B.; Bickler, D. B.; Gallagher, B. D. (inventors)

1985-01-01

423

High voltage pulse conditioning  

DOEpatents

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.

Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

1990-01-01

424

Evaluation of protein stability and in vitro permeation of lyophilized polysaccharides-based microparticles for intranasal protein delivery.  

PubMed

Biocompatible microparticles prepared by lyophilization were developed for intranasal protein delivery. To test for the feasibility of this formulation, stability of the incorporated protein and enhancement of in vitro permeation across the nasal epithelium were evaluated. Lyophilization was processed with hydroxypropylmethylcellulose (HPMC) or water soluble chitosan (WCS) as biocompatible polymers, hydroxypropyl-?-cyclodextrin (HP-?-CD) and d-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) as permeation enhancers, sugars as cryoprotectants and lysozyme as the model protein. As a result, microparticles ranging from 6 to 12?m were developed where the maintenance of the protein conformation was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism and fluorescence intensity detection. Moreover, in vitro bioassay showed that the lysozyme activity was preserved during the preparation process while exhibiting less cytotoxicity in primary human nasal epithelial (HNE) cells. Results of the in vitro release study revealed slower release rate in these microparticles compared to that of the lysozyme itself. On the other hand, the in vitro permeation study exhibited a 9-fold increase in absorption of lysozyme when prepared in lyophilized microparticles with HPMC, HP-?-CD and TPGS 1000 (F4-2). These microparticles could serve as efficient intranasal delivery systems for therapeutic proteins. PMID:21703339

Cho, Hyun-Jong; Balakrishnan, Prabagar; Chung, Suk-Jae; Shim, Chang-Koo; Kim, Dae-Duk

2011-09-15

425

Efficient evaluation of process stability in milling with Spindle Speed Variation by using the Chebyshev Collocation Method  

NASA Astrophysics Data System (ADS)

Chatter is a vibrational problem affecting machining operations, which may cause bad surface quality and damages to the machining system. In recent decades, several techniques for avoiding chatter onset were developed. Among other techniques, the continuous modulation of spindle speed during the cutting process (also called Spindle Speed Variation - SSV) has been demonstrated to be very effective for reducing the chance of chatter onset. However, spindle speed modulation parameters should be adequately chosen before machining, in order to effectively increase the material removal rate. In this perspective, chatter prediction algorithms play a crucial role, since they allow a preventive evaluation of process stability for any given spindle speed regime. State of the art algorithms for chatter prediction in milling with SSV are characterized by extremely long computation times, hindering their practical application in industry. In this paper, an innovative and fast algorithm for chatter prediction in milling with SSV, based on the Chebyshev Collocation Method, is presented. The algorithm was successfully compared with a state of the art algorithm - the Semi Discretization Method - in different experimental configurations and cutting conditions. The results showed that the new method is generally more accurate and from ten to one thousand times faster than the Semi Discretization Method.

Totis, G.; Albertelli, P.; Sortino, M.; Monno, M.

2014-02-01

426

High voltage variable diameter insulator  

DOEpatents

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).

Vanecek, David L. (Martinez, CA); Pike, Chester D. (Pinole, CA)

1984-01-01

427

Low-voltage polyphasic circuits  

NASA Astrophysics Data System (ADS)

Experimentation with polyphasic voltages is greatly simplified when microcontrollers are used to generate multiple square waves with fixed phase offsets. Each square wave is sent through a simple second-order Sallen-Key filter to produce an approximately sinusoidal voltage signal. The microcontroller allows the reproduction of split-phase and three-phase voltage relationships, mirroring those commonly distributed on the North American power grid, at safe voltage levels.

Baird, William H.; Jaynes, Michael L.

2010-05-01

428

Charge-pump voltage converter  

DOEpatents

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.

Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

2009-11-03

429

Voltage regulation and battery condition  

Microsoft Academic Search

Charging of automotive lead--acid batteries and the related aspects of voltage regulators are reviewed. Operation and proper setting of voltage regulators for different conditions are discussed. Factors affecting battery counter voltage (cemf) are examined: these include purity of battery materials, state of charge, strength of electrolyte, gassing, maintenance, and temperature--the latter is considered at some length. (RWR)

Wesley

1977-01-01

430

Evaluation of the longitudinal stability and control characteristics of a mixed-flow remote-lift STOVL aircraft in transition and hover  

NASA Technical Reports Server (NTRS)

An evaluation of the longitudinal stability and control characteristics of a mixed-flow remote-lift (MFRL) STOVL aircraft in the powered-lift portion of the flight envelope is presented. A stabilization and command augmentation system was implemented on the MFRL aircraft to meet the requirements for satisfactory flying qualities. The pitch portion of this control system uses a state-rate feedback implicit model following controller to achieve the desired flying qualities and to suppress the effects of external variations and disturbances in the aircrafts characteristics over the low speed envelope.

Engelland, Shawn A.

1991-01-01

431

Intermediate state trapping of a voltage sensor  

PubMed Central

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

Lacroix, Jérôme J.; Pless, Stephan A.; Maragliano, Luca; Campos, Fabiana V.; Galpin, Jason D.; Ahern, Christopher A.; Roux, Benoît

2012-01-01

432

Proposal of the new method to evaluate of the tectonic stability for the last 100 ky in Japan  

NASA Astrophysics Data System (ADS)

1. INTRODUCTION To evaluate the long-term safety of underground high-level radioactive waste repository, it is important to predict futureOs tectonic events, particularly tectonic uplift/subsidence, faulting, earthquake and volcanic activity. FutureOs activity is generally predicted by extrapolation of past tectonic characteristics. However, it is difficult to construct the 2-dimensional distribution of the past uplift/subsidence rate including inland area. In this study, we estimate uplift rate of inland area and propose the method to draw up the tectonic map for the last 100 ky. 2. METHOD First, in the study area, the uplift/subsidence rate for the last 100 ky is estimated using terraces and boring data, and characteristics of the 2-dimensional distribution of uplift/subsidence rate is investigated. Second, geological and geophysical data showing inhomogeneity and stress condition in the upper crust, and geodetic data showing the short-term displacement near the ground surface are compiled. Finally, characteristics common to the uplift/subsidence rate distribution and other data are summarized, and tectonic blocks defined as an area that has same tectonic characteristics are identified in the studied area. The uplift rate was estimated basically by the altitude of marine terrace formed in stage 5e in the coastal area. In the inland area, the uplift rate was estimated by the relative height between the two river terraces that had been formed in the same climate condition and different age, i.e. glacial age (stage 2-stage 6) and interglacial age (present-stage 5e). The subsidence rate was estimated by the buried depth of marker beds whose ages had been determined by boring data, geophysical prospecting profiles etc. 3. APPLICATION We applied the proposed method to the Hokkaido Island, northern part of Japan. We newly obtained the uplift data using river terraces in the inland areas, and compiled geological, geophysical and geodetic data. On the basis of the characteristics common to all data, we divided the studied area into several tectonic blocks. Each block has individual characteristics of tectonic style, i.e. uplift rate, deformation, volcanic activities, etc. This tectonic blocking can be explained mainly by the oblique subduction of the Pacific plate to the North American plate and a collision of the Chishima arc due to the collision, and also suggests that another tectonic boundary distribute in the Japan Sea. Therefore, the applicability of the proposed method to evaluate the long-term tectonic stability for the last 100 ky is thought to be verified. 4. CONCLUSION We proposed the new method to evaluate the long-term tectonic stability in the local area. Tectonic blocks identified by our method should help the site selection by the following investigation; 1) Is tectonic activity is high or low? 2) Is the block large or small? 3) How far is a candidate site from the block boundary? etc. * This study was financially supported by ten electric power companies in Japan.

Hataya, R.; Tanaka, K.

2001-12-01

433

Evaluation of Colloidal Stability and Ecotoxicity of Metal-based Nanoparticles in the Aquatic and Terrestrial Systems  

NASA Astrophysics Data System (ADS)

Intrinsic to the many nano-enabled products are atomic-size multifunctional engineered nanomaterials, which upon release contaminate the environments, raising considerable health and safety concerns. This Ph.D. dissertation is designed to investigate (i) whether metals or oxide nanoparticles are more toxic than ions, and if MetPLATE(TM) bioassay is applicable as a rapid nanotoxicity screening tool; (ii) how variable water chemistry (dissolved organic carbon (DOC), pH, and hardness) and organic compounds (cysteine, humic acid, and trolox) modulate colloidal stability, ion release, and aquatic toxicity of silver nanoparticles (AgNP); and (iii) the developmental responses of crop plants exposed to Ag- or ZnO- (zinc oxide) nanoparticles. Results suggest that the MetPLATE can be considered a high-throughput screening tool for rapid nanotoxicity evaluation. Detectable changes in the colloidal diameter, surface charge, and plasmonic resonance revealed modulating effects of variable water chemistry and organic ligands on the particle stability, dissolution, and toxicity of AgNPs against Escherichia coli or Daphnia magna. Silver dissolution increased as a function of DOC concentrations but decreased with increasing hardness, pH, cysteine, or trolox levels. Notably, the dissociated Ag+ was inadequate to explain AgNP toxicity, and that the combined effect of AgNPs and dissolved Ag+ under each ligand treatment was lower than of AgNO 3. Significant attenuation by trolox signifies an oxidative stress-mediated AgNP toxicity; its inability to attenuate AgNO3 toxicity, however, negates oxidative stress as Ag+ toxicity mechanism, and that cysteine could effectively quench free Ag+ to alleviate AgNO 3 toxicity in D. magna. Surprisingly, DOC-AgNPs complex that apparently formed at higher DOC levels might have led daphnids filter-feed on aggregates, potentially elevating internal dose, and thus higher mortality. Maize root anatomy showed differential alterations upon exposure to AgNPs, ZnONPs, or their ions. Overall, various metal-based nanoparticles revealed lower toxicity than their ions against multiple organisms. This study showed that particle size, surface properties, and ion release kinetics of AgNPs modify following release into aquatic environment, suggesting potential implications to ecosystem health and functions, and that caution be applied when extending one species toxicity results to another because obvious differences in organism biology---supporting species sensitivity paradigm---can significantly alter nanoparticle or ionic toxicity.

Pokhrel, Lok Raj

434

Evaluation of stability and size distribution of sunflower oil-coated micro bubbles for localized drug delivery  

PubMed Central

Background Micro bubbles were initially introduced as contrast agents for ultrasound examinations as they are able to modify the signal-to-noise ratio in imaging, thus improving the assessment of clinical information on human tissue. Recent developments have demonstrated the feasibility of using these bubbles as drug carriers in localized delivery. In micro fluidics devices for generation of micro bubbles, the bubbles are formed at interface of liquid gas through a strangulation process. A device that uses these features can produce micro bubbles with small size dispersion in a single step. Methods A T-junction micro fluidic device constructed using 3D prototyping was made for the production of mono dispersed micro bubbles. These micro bubbles use sunflower oil as a lipid layer. Stability studies for micro bubbles with diameters different generated from a liquid phase of the same viscosity were conducted to evaluate whether micro bubbles can be used as drug carriers. The biocompatibility of coating layer, the ability to withstand environmental pressure variations combined with echogenicity, are key factors that they can safely play the role of drug transporters. Results The normal distribution curve with small dispersion of the diameter of bubbles validates the process of generating micro bubbles with low value of variation coefficient, i.e., 0.381 at 1.90%. The results also showed the feasibility of using sunflower oil as the lipid matrix with stable population of bubbles over 217 minutes for micro bubbles with an average diameter of 313.04 ?m and 121 minutes for micro bubbles with an average diameter of 73.74 ?m, considering bubbles with air as gaseous phase. Conclusion The results indicate that the micro fluidic device designed can be used for producing micro bubbles with low variation coefficient using sunflower oil as a coating of micro bubbles. These carriers were stable for periods of time that are long enough for clinical applications even when regular air is used as the gas phase. Improved stability can be achieved when biocompatible gas with lower permeability is used. PMID:22995578

2012-01-01

435

Atomistic Simulation and Virtual Diffraction Characterization of Alumina Interfaces: Evaluating Structure and Stability for Predictive Physical Vapor Deposition Models  

NASA Astrophysics Data System (ADS)

The objectives of this work are to investigate the structure and energetic stability of different alumina (Al2O3) phases using atomistic simulation and virtual diffraction characterization. To meet these objectives, this research performs molecular statics and molecular dynamics simulations employing the reactive force-field (ReaxFF) potential to model bulk, interface, and surface structures in the theta-, gamma-, kappa-, and ?-Al2O3 system. Simulations throughout this study are characterized using a new virtual diffraction algorithm, developed and implemented for this work, that creates both selected area electron diffraction (SAED) and x-ray diffraction (XRD) line profiles without assuming prior knowledge of the crystal system. First, the transferability of the ReaxFF potential is evaluated by modelling different alumina bulk systems. ReaxFF is shown to correctly predict the energetic stability of ?-Al2O 3 among the crystalline alumina phases, but incorrectly predicts an even lower energy amorphous phase. Virtual XRD patterns uniquely identify each phase and validate the minimum energy bulk structures through experimental comparison. Second, stable and metastable alumina surfaces are studied at 0, 300, 500, and 700 K. ReaxFF predicts minimum energy surface structures and energies in good agreement with prior studies at 0 K; however, select surface models at 500 and 700 K undergo significant reconstructions caused by the unnatural bias for a lower-energy amorphous phase. Virtual SAED analysis performed on alumina surfaces allow advanced characterization and direct experimental validation of select models. Third, ReaxFF is used to model homophase and heterophase alumina interfaces at 0 K. Predicted minimum energy structures of ?-Al2O3 interfaces show good agreement with prior works, which provides the foundation for the first atomistic study of metastable alumina grain boundaries and heterophase alumina interfaces. Virtual SAED patterns characterize select alumina interfaces and help guide the construction of low-energy heterophase alumina interfaces by providing insight into crystallographic compatibilities. Combined, the energetic data extracted from bulk, surface, and interface simulations as well as insights gained through virtual diffraction will aid the development of mesoscale predictive models of polycrystalline alumina formation during physical vapor deposition.

Coleman, Shawn

436

Numerical evaluation of currents induced in a worker by ELF non-uniform electric fields in high voltage substations and comparison with experimental results.  

PubMed

An ungrounded human, such as a substation worker, receives contact currents when touching a grounded object in electric fields. In this article, contact currents and internal electric fields induced in the human when exposed to non-uniform electric fields at 50?Hz are numerically calculated. This is done using a realistic human model standing at a distance of 0.1-0.5?m from the grounded conductive object. We found that the relationship between the external electric field strength and the contact current obtained by calculation is in good agreement with previous measurements. Calculated results show that the contact currents largely depend on the distance, and that the induced electric fields in the tissues are proportional to the contact current regardless of the non-uniformity of the external electric field. Therefore, it is concluded that the contact current, rather than the spatial average of the external electric field, is more suitable for evaluating electric field dosimetry of tissues. The maximum induced electric field appears in the spinal cord in the central nervous system tissues, with the induced electric field in the spinal cord approaching the basic restriction (100?mV/m) of the new 2010 International Commission on Non-Ionizing Radiation Protection guidelines for occupational exposure, if the contact current is 0.5?mA. PMID:22684733

Tarao, Hiroo; Korpinen, Leena H; Kuisti, Harri A; Hayashi, Noriyuki; Elovaara, Jarmo A; Isaka, Katsuo

2013-01-01

437

Head Stabilization Measurements as a Potential Evaluation Tool for Comparison of Persons With TBI and Vestibular Dysfunction With Healthy Controls.  

PubMed

A large percentage of persons with traumatic brain injury incur some type of vestibular dysfunction requiring vestibular physical therapy. These injuries may affect the natural ability to stabilize the head while walking. A simple method of utilizing motion capture equipment to measure head movement while walking was used to assess improvements in head stabilization of persons undergoing computerized vestibular physical therapy and virtual reality training for treatment of their vestibular problems. Movement data from the head and sacrum during gait were obtained over several visits and then analyzed to determine improved oscillatory head movement relative to the sacrum. The data suggest that, over time with treatment, head stabilization improves and moves toward a pattern similar to that of a healthy control population. This simple analysis of measuring head stability could be transferred to smaller, portable systems that are easily utilized to measure head stability during gait for use in gait assessment and physical therapy training. PMID:25747644

Sessoms, Pinata H; Gottshall, Kim R; Sturdy, Jordan; Viirre, Erik

2015-03-01

438

Threshold voltage extraction circuit  

E-print Network

NMOS transistor obtained via simulation. 27 Simulation P MOS 9. 6/2. 4 9 I I I I B to X 6g C 0 III ) "b 0 -'LfaS NI) Fig. 17. Graph of 4o and 8(V)n)/8(Vcs) versus Vcs of a PMOS transistor obtained via simulation. SIMULATION RESULTS...ltm/2. 4ltm). 33 Temperature ('C) E Cl Qt nt O 'D O ta I -820 -880 Postlayout Simulation TOt S Fig. 21. Temperature dependence of threshold-voltage of a PMOS transistor ( W/I ? 9. 6ltm/2. 4ltm). In the following subsection, chip...

Hoon, Siew Kuok

2000-01-01

439

Frequency to Voltage Converter Analog Front-End Prototype  

NASA Technical Reports Server (NTRS)

The frequency to voltage converter analog front end evaluation prototype (F2V AFE) is an evaluation board designed for comparison of different methods of accurately extracting the frequency of a sinusoidal input signal. A configurable input stage is routed to one or several of five separate, configurable filtering circuits, and then to a configurable output stage. Amplifier selection and gain, filter corner frequencies, and comparator hysteresis and voltage reference are all easily configurable through the use of jumpers and potentiometers.

Mata, Carlos; Raines, Matthew

2012-01-01

440

Planned Variation in Preanalytical Conditions to Evaluate Biospecimen Stability in the National Children’s Study (NCS)  

PubMed Central

BACKGROUND Preanalytical conditions encountered during collection, processing, and storage of biospecimens may influence laboratory results. The National Children’s Study (NCS) is a planned prospective cohort study of 100,000 families to examine the influence of a wide variety of exposures on child health. In developing biospecimen collection, processing, and storage procedures for the NCS, we identified several analytes of different biochemical categories for which it was unclear to what extent deviations from NCS procedures could influence measurement results. METHODS A pilot study was performed to examine effects of preanalytic sample handling conditions (delays in centrifugation, freezing delays, delays in separation from cells, additive delay, and tube type) on concentrations of eight different analytes. 2,825 measurements were made to assess 15 unique combinations of analyte and handling conditions in blood collected from 151 women of childbearing age (?20 individuals per handling condition). RESULTS The majority of analytes were stable under the conditions evaluated. However, levels of plasma interleukin-6 and serum insulin were decreased in response to sample centrifugation delays of up to 5.5 hours post collection (P<0.0001). In addition, delays in freezing centrifuged plasma samples (comparing 24, 48 and 72 hours to immediate freezing) resulted in increased levels of adrenocorticotropic hormone (P=0.0014). CONCLUSIONS Determining stability of proposed analytes in response to preanalytical conditions and handling helps to ensure high-quality specimens for study now and in the future. The results inform development of procedures, plans for measurement of analytes, and interpretation of laboratory results. PMID:23924524

Mechanic, Leah; Mendez, Armando; Merrill, Lori; Rogers, John; Layton, Marnie; Todd, Deborah; Varanasi, Arti; O’Brien, Barbara; Meyer, William A.; Zhang, Ming; Schleicher, Rosemary L.; Moye, Jack

2014-01-01

441

Three dimensional fluorescent spectroscopy analysis for the evaluation of organic matter removal from industrial estate wastewater by stabilization ponds.  

PubMed

The fluorescent excitation emission matrix (FEEM) was utilized to evaluate the removal of organic matter by stabilization ponds, which consist of aeration, facultative, and oxidation ponds of a central wastewater treatment plant of an industrial estate in northern Thailand. The result shows that six fluorescent peaks of influent wastewater and effluent water after aeration, facultative, and oxidation ponds were detected from the FEEMs at 230 nmEx/295 nmEm (A), 275 nmEx/300 nmEm (B), 240 nmEx/355 nmEm (C), 280 nmEx/355 nmEm (D), 275 nmEx/410 nmEm (E) and 330 nmEx/410 nmEm (F). The putative origins of peaks A and B, C and D, and E and F were tyrosine-like, tryptophan-like, and humic and fulvic acid-like substances, respectively. The aeration pond was the main course of action used to reduce the tyrosine-like substances at peaks A and B by 88 and 52%, respectively, and tryptophan-like substances at peaks C and D by 43 and 39%, respectively. There was only a 20 per cent decrease of humic and fulvic acid-like substances at peak E and an 18 per cent decrease at peak F through the use of aeration ponds. Total per cent reductions of total fluorescent organic matter after aeration ponds; facultative ponds; and oxidation ponds were 46, 51 and 54%, respectively. These values were notably similar to the total percent reduction of DOC by the same respective processes at 54, 53, and 55%. PMID:17591213

Musikavong, C; Wattanachira, S; Nakajima, F; Furumai, H

2007-01-01

442