Development and validity of an instrumented handbike: initial results of propulsion kinetics.

PubMed

van Drongelen, Stefan; van den Berg, Jos; Arnet, Ursina; Veeger, Dirkjan H E J; van der Woude, Lucas H V

2011-11-01

To develop an instrumented handbike system to measure the forces applied to the handgrip during handbiking. A 6 degrees of freedom force sensor was built into the handgrip of an attach-unit handbike, together with two optical encoders to measure the orientation of the handgrip and crank in space. Linearity, precision, and percent error were determined for static and dynamic tests. High linearity was demonstrated for both the static and the dynamic condition (r=1.01). Precision was high under the static condition (standard deviation of 0.2N), however the precision decreased with higher loads during the dynamic condition. Percent error values were between 0.3 and 5.1%. This is the first instrumented handbike system that can register 3-dimensional forces. It can be concluded that the instrumented handbike system allows for an accurate force analysis based on forces registered at the handle bars. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Development of an ultrasonic linear motor with ultra-positioning capability and four driving feet.

PubMed

Zhu, Cong; Chu, Xiangcheng; Yuan, Songmei; Zhong, Zuojin; Zhao, Yanqiang; Gao, Shuning

2016-12-01

This paper presents a novel linear piezoelectric motor which is suitable for rapid ultra-precision positioning. The finite element analysis (FEA) was applied for optimal design and further analysis, then experiments were conducted to investigate its performance. By changing the input signal, the proposed motor was found capable of working in the fast driving mode as well as in the precision positioning mode. When working in the fast driving mode, the motor acts as an ultrasonic motor with maximum no-load speed up to 181.2mm/s and maximum thrust of 1.7N at 200Vp-p. Also, when working in precision positioning mode, the motor can be regarded as a flexible hinge piezoelectric actuator with arbitrary motion in the range of 8μm. The measurable minimum output displacement was found to be 0.08μm, but theoretically, can be even smaller. More importantly, the motor can be quickly and accurately positioned in a large stroke. Copyright © 2016 Elsevier B.V. All rights reserved.

The instantaneous linear motion information measurement method based on inertial sensors for ships

NASA Astrophysics Data System (ADS)

Yang, Xu; Huang, Jing; Gao, Chen; Quan, Wei; Li, Ming; Zhang, Yanshun

2018-05-01

Ship instantaneous line motion information is the important foundation for ship control, which needs to be measured accurately. For this purpose, an instantaneous line motion measurement method based on inertial sensors is put forward for ships. By introducing a half-fixed coordinate system to realize the separation between instantaneous line motion and ship master movement, the instantaneous line motion acceleration of ships can be obtained with higher accuracy. Then, the digital high-pass filter is applied to suppress the velocity error caused by the low frequency signal such as schuler period. Finally, the instantaneous linear motion displacement of ships can be measured accurately. Simulation experimental results show that the method is reliable and effective, and can realize the precise measurement of velocity and displacement of instantaneous line motion for ships.

Non-contact measurement of linear external dimensions of the mouse eye

PubMed Central

Wisard, Jeffrey; Chrenek, Micah A.; Wright, Charles; Dalal, Nupur; Pardue, Machelle T.; Boatright, Jeffrey H.; Nickerson, John M.

2010-01-01

Biometric analyses of quantitative traits in eyes of mice can reveal abnormalities related to refractive or ocular development. Due to the small size of the mouse eye, highly accurate and precise measurements are needed to detect meaningful differences. We sought a non-contact measuring technique to obtain highly accurate and precise linear dimensions of the mouse eye. Laser micrometry was validated with gauge block standards. Simple procedures to measure eye dimensions on three axes were devised. Mouse eyes from C57BL/6J and rd10 on a C57BL/6J background were dissected and extraocular muscle and fat removed. External eye dimensions of axial length (anterior-posterior (A-P) axis) and equatorial diameter (superior-inferior (S-I) and nasal-temporal (N-T) axes) were obtained with a laser micrometer. Several approaches to prevent or ameliorate evaporation due to room air were employed. The resolution of the laser micrometer was less than 0.77 microns, and it provided accurate and precise non-contact measurements of eye dimensions on three axes. External dimensions of the eye strongly correlated with eye weight. The N-T and S-I dimensions of the eye correlated with each other most closely from among the 28 pair-wise combinations of the several parameters that were collected. The equatorial axis measurements correlated well from the right and left eye of each mouse. The A-P measurements did not correlate or correlated poorly in each pair of eyes. The instrument is well suited for the measurement of enucleated eyes and other structures from most commonly used species in experimental vision research and ophthalmology. PMID:20067806

Measurement of atmospheric ozone by cavity ring-down spectroscopy.

PubMed

Washenfelder, R A; Wagner, N L; Dube, W P; Brown, S S

2011-04-01

Ozone plays a key role in both the Earth's radiative budget and photochemistry. Accurate, robust analytical techniques for measuring its atmospheric abundance are of critical importance. Cavity ring-down spectroscopy has been successfully used for sensitive and accurate measurements of many atmospheric species. However, this technique has not been used for atmospheric measurements of ozone, because the strongest ozone absorption bands occur in the ultraviolet spectral region, where Rayleigh and Mie scattering cause significant cavity losses and dielectric mirror reflectivities are limited. Here, we describe a compact instrument that measures O3 by chemical conversion to NO2 in excess NO, with subsequent detection by cavity ring-down spectroscopy. This method provides a simple, accurate, and high-precision measurement of atmospheric ozone. The instrument consists of two channels. The sum of NO2 and converted O3 (defined as Ox) is measured in the first channel, while NO2 alone is measured in the second channel. NO2 is directly detected in each channel by cavity ring-down spectroscopy with a laser diode light source at 404 nm. The limit of detection for O3 is 26 pptv (2 sigma precision) at 1 s time resolution. The accuracy of the measurement is ±2.2%, with the largest uncertainty being the effective NO2 absorption cross-section. The linear dynamic range of the instrument has been verified from the detection limit to above 200 ppbv (r2>99.99%). The observed precision on signal (2 sigma) with 41 ppbv O3 is 130 pptv in 1 s. Comparison of this instrument to UV absorbance instruments for ambient O3 concentrations shows linear agreement (r2=99.1%) with slope of 1.012±0.002.

Non-contact measurement of linear external dimensions of the mouse eye.

PubMed

Wisard, Jeffrey; Chrenek, Micah A; Wright, Charles; Dalal, Nupur; Pardue, Machelle T; Boatright, Jeffrey H; Nickerson, John M

2010-03-30

Biometric analyses of quantitative traits in eyes of mice can reveal abnormalities related to refractive or ocular development. Due to the small size of the mouse eye, highly accurate and precise measurements are needed to detect meaningful differences. We sought a non-contact measuring technique to obtain highly accurate and precise linear dimensions of the mouse eye. Laser micrometry was validated with gauge block standards. Simple procedures to measure eye dimensions on three axes were devised. Mouse eyes from C57BL/6J and rd10 on a C57BL/6J background were dissected and extraocular muscle and fat removed. External eye dimensions of axial length (anterior-posterior (A-P) axis) and equatorial diameter (superior-inferior (S-I) and nasal-temporal (N-T) axes) were obtained with a laser micrometer. Several approaches to prevent or ameliorate evaporation due to room air were employed. The resolution of the laser micrometer was less than 0.77 microm, and it provided accurate and precise non-contact measurements of eye dimensions on three axes. External dimensions of the eye strongly correlated with eye weight. The N-T and S-I dimensions of the eye correlated with each other most closely from among the 28 pair-wise combinations of the several parameters that were collected. The equatorial axis measurements correlated well from the right and left eye of each mouse. The A-P measurements did not correlate or correlated poorly in each pair of eyes. The instrument is well suited for the measurement of enucleated eyes and other structures from most commonly used species in experimental vision research and ophthalmology. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Performance characteristics of two bioassays and high-performance liquid chromatography for determination of flucytosine in serum.

PubMed Central

St-Germain, G; Lapierre, S; Tessier, D

1989-01-01

We compared the accuracy and precision of two microbiological methods and one high-pressure liquid chromatography (HPLC) procedure used to measure the concentrations of flucytosine in serum. On the basis of an analysis of six standards, all methods were judged reliable within acceptable limits for clinical use. With the biological methods, a slight loss of linearity was observed in the 75- to 100-micrograms/ml range. Compared with the bioassays, the HPLC method did not present linearity problems and was more precise and accurate in the critical zone of 100 micrograms/ml. On average, results obtained with patient sera containing 50 to 100 micrograms of flucytosine per ml were 10.6% higher with the HPLC method than with the bioassays. Standards for the biological assays may be prepared in serum or water. PMID:2802566

Direct computation of general chemical energy differences: Application to ionization potentials, excitation, and bond energies.

PubMed

Beste, A; Harrison, R J; Yanai, T

2006-08-21

Chemists are mainly interested in energy differences. In contrast, most quantum chemical methods yield the total energy which is a large number compared to the difference and has therefore to be computed to a higher relative precision than would be necessary for the difference alone. Hence, it is desirable to compute energy differences directly, thereby avoiding the precision problem. Whenever it is possible to find a parameter which transforms smoothly from an initial to a final state, the energy difference can be obtained by integrating the energy derivative with respect to that parameter (cf. thermodynamic integration or adiabatic connection methods). If the dependence on the parameter is predominantly linear, accurate results can be obtained by single-point integration. In density functional theory and Hartree-Fock, we applied the formalism to ionization potentials, excitation energies, and chemical bond breaking. Example calculations for ionization potentials and excitation energies showed that accurate results could be obtained with a linear estimate. For breaking bonds, we introduce a nongeometrical parameter which gradually turns the interaction between two fragments of a molecule on. The interaction changes the potentials used to determine the orbitals as well as the constraint on the orbitals to be orthogonal.

Development and Validation of Different Ultraviolet-Spectrophotometric Methods for the Estimation of Besifloxacin in Different Simulated Body Fluids.

PubMed

Singh, C L; Singh, A; Kumar, S; Kumar, M; Sharma, P K; Majumdar, D K

2015-01-01

In the present study a simple, accurate, precise, economical and specific UV-spectrophotometric method for estimation of besifloxacin in bulk and in different pharmaceutical formulation has been developed. The drug shows maximum λmax289 nm in distilled water, simulated tears and phosphate buffer saline. The linearity range of developed methods were in the range of 3-30 μg/ml of drug with a correlation coefficient (r(2)) 0.9992, 0.9989 and 0.9984 with respect to distilled water, simulated tears and phosphate buffer saline, respectively. Reproducibility by repeating methods as %RSD were found to be less than 2%. The limit of detection in different media was found to be 0.62, 0.72 and 0.88 μg/ml, respectively. The limit of quantification was found to be 1.88, 2.10, 2.60 μg/ml, respectively. The proposed method was validated statically according to International Conference on Harmonization guidelines with respect to specificity, linearity, range, accuracy, precision and robustness. The proposed methods of validation were found to be accurate and highly specific for the estimation of besifloxacin in different pharmaceutical formulations.

[Validation of an in-house method for the determination of zinc in serum: Meeting the requirements of ISO 17025].

PubMed

Llorente Ballesteros, M T; Navarro Serrano, I; López Colón, J L

2015-01-01

The aim of this report is to propose a scheme for validation of an analytical technique according to ISO 17025. According to ISO 17025, the fundamental parameters tested were: selectivity, calibration model, precision, accuracy, uncertainty of measurement, and analytical interference. A protocol has been developed that has been applied successfully to quantify zinc in serum by atomic absorption spectrometry. It is demonstrated that our method is selective, linear, accurate, and precise, making it suitable for use in routine diagnostics. Copyright © 2015 SECA. Published by Elsevier Espana. All rights reserved.

A novel methodology for non-linear system identification of battery cells used in non-road hybrid electric vehicles

NASA Astrophysics Data System (ADS)

Unger, Johannes; Hametner, Christoph; Jakubek, Stefan; Quasthoff, Marcus

2014-12-01

An accurate state of charge (SoC) estimation of a traction battery in hybrid electric non-road vehicles, which possess higher dynamics and power densities than on-road vehicles, requires a precise battery cell terminal voltage model. This paper presents a novel methodology for non-linear system identification of battery cells to obtain precise battery models. The methodology comprises the architecture of local model networks (LMN) and optimal model based design of experiments (DoE). Three main novelties are proposed: 1) Optimal model based DoE, which aims to high dynamically excite the battery cells at load ranges frequently used in operation. 2) The integration of corresponding inputs in the LMN to regard the non-linearities SoC, relaxation, hysteresis as well as temperature effects. 3) Enhancements to the local linear model tree (LOLIMOT) construction algorithm, to achieve a physical appropriate interpretation of the LMN. The framework is applicable for different battery cell chemistries and different temperatures, and is real time capable, which is shown on an industrial PC. The accuracy of the obtained non-linear battery model is demonstrated on cells with different chemistries and temperatures. The results show significant improvement due to optimal experiment design and integration of the battery non-linearities within the LMN structure.

Accurate determination of reference materials and natural isolates by means of quantitative (1)h NMR spectroscopy.

PubMed

Frank, Oliver; Kreissl, Johanna Karoline; Daschner, Andreas; Hofmann, Thomas

2014-03-26

A fast and precise proton nuclear magnetic resonance (qHNMR) method for the quantitative determination of low molecular weight target molecules in reference materials and natural isolates has been validated using ERETIC 2 (Electronic REference To access In vivo Concentrations) based on the PULCON (PULse length based CONcentration determination) methodology and compared to the gravimetric results. Using an Avance III NMR spectrometer (400 MHz) equipped with a broad band observe (BBO) probe, the qHNMR method was validated by determining its linearity, range, precision, and accuracy as well as robustness and limit of quantitation. The linearity of the method was assessed by measuring samples of l-tyrosine, caffeine, or benzoic acid in a concentration range between 0.3 and 16.5 mmol/L (r(2) ≥ 0.99), whereas the interday and intraday precisions were found to be ≤2%. The recovery of a range of reference compounds was ≥98.5%, thus demonstrating the qHNMR method as a precise tool for the rapid quantitation (~15 min) of food-related target compounds in reference materials and natural isolates such as nucleotides, polyphenols, or cyclic peptides.

Accuracy and Precision in Measurements of Biomass Oxidative Ratio and Carbon Oxidation State

NASA Astrophysics Data System (ADS)

Gallagher, M. E.; Masiello, C. A.; Randerson, J. T.; Chadwick, O. A.; Robertson, G. P.

2007-12-01

Ecosystem oxidative ratio (OR) is a critical parameter in the apportionment of anthropogenic CO2 between the terrestrial biosphere and ocean carbon reservoirs. OR is the ratio of O2 to CO2 in gas exchange fluxes between the terrestrial biosphere and atmosphere. Ecosystem OR is linearly related to biomass carbon oxidation state (Cox), a fundamental property of the earth system describing the bonding environment of carbon in molecules. Cox can range from -4 to +4 (CH4 to CO2). Variations in both Cox and OR are driven by photosynthesis, respiration, and decomposition. We are developing several techniques to accurately measure variations in ecosystem Cox and OR; these include elemental analysis, bomb calorimetry, and 13C nuclear magnetic resonance spectroscopy. A previous study, comparing the accuracy and precision of elemental analysis versus bomb calorimetry for pure chemicals, showed that elemental analysis-based measurements are more accurate, while calorimetry- based measurements yield more precise data. However, the limited biochemical range of natural samples makes it possible that calorimetry may ultimately prove most accurate, as well as most cost-effective. Here we examine more closely the accuracy of Cox and OR values generated by calorimetry on a large set of natural biomass samples collected from the Kellogg Biological Station-Long Term Ecological Research (KBS-LTER) site in Michigan.

Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation

PubMed Central

Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

2014-01-01

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75 ÷ 12.50 μg·spot−1, and from 1.00 ÷ 2.50 μg·spot−1 for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1 and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia. PMID:24526880

Validation of a thin-layer chromatography for the determination of hydrocortisone acetate and lidocaine in a pharmaceutical preparation.

PubMed

Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

2014-01-01

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform+acetone+ammonia (25%) in volume composition 8:2:0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75÷12.50  μg·spot(-1), and from 1.00÷2.50  μg·spot(-1) for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198  μg·spot(-1) and LOD is 0.066  μg·spot(-1). LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090  μg·spot(-1), respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia.

Neural decoding of treadmill walking from noninvasive electroencephalographic signals

PubMed Central

Presacco, Alessandro; Goodman, Ronald; Forrester, Larry

2011-01-01

Chronic recordings from ensembles of cortical neurons in primary motor and somatosensory areas in rhesus macaques provide accurate information about bipedal locomotion (Fitzsimmons NA, Lebedev MA, Peikon ID, Nicolelis MA. Front Integr Neurosci 3: 3, 2009). Here we show that the linear and angular kinematics of the ankle, knee, and hip joints during both normal and precision (attentive) human treadmill walking can be inferred from noninvasive scalp electroencephalography (EEG) with decoding accuracies comparable to those from neural decoders based on multiple single-unit activities (SUAs) recorded in nonhuman primates. Six healthy adults were recorded. Participants were asked to walk on a treadmill at their self-selected comfortable speed while receiving visual feedback of their lower limbs (i.e., precision walking), to repeatedly avoid stepping on a strip drawn on the treadmill belt. Angular and linear kinematics of the left and right hip, knee, and ankle joints and EEG were recorded, and neural decoders were designed and optimized with cross-validation procedures. Of note, the optimal set of electrodes of these decoders were also used to accurately infer gait trajectories in a normal walking task that did not require subjects to control and monitor their foot placement. Our results indicate a high involvement of a fronto-posterior cortical network in the control of both precision and normal walking and suggest that EEG signals can be used to study in real time the cortical dynamics of walking and to develop brain-machine interfaces aimed at restoring human gait function. PMID:21768121

Ion chromatography for the precise analysis of chloride and sodium in sweat for the diagnosis of cystic fibrosis.

PubMed

Doorn, J; Storteboom, T T R; Mulder, A M; de Jong, W H A; Rottier, B L; Kema, I P

2015-07-01

Measurement of chloride in sweat is an essential part of the diagnostic algorithm for cystic fibrosis. The lack in sensitivity and reproducibility of current methods led us to develop an ion chromatography/high-performance liquid chromatography (IC/HPLC) method, suitable for the analysis of both chloride and sodium in small volumes of sweat. Precision, linearity and limit of detection of an in-house developed IC/HPLC method were established. Method comparison between the newly developed IC/HPLC method and the traditional Chlorocounter was performed, and trueness was determined using Passing Bablok method comparison with external quality assurance material (Royal College of Pathologists of Australasia). Precision and linearity fulfill criteria as established by UK guidelines are comparable with inductively coupled plasma-mass spectrometry methods. Passing Bablok analysis demonstrated excellent correlation between IC/HPLC measurements and external quality assessment target values, for both chloride and sodium. With a limit of quantitation of 0.95 mmol/L, our method is suitable for the analysis of small amounts of sweat and can thus be used in combination with the Macroduct collection system. Although a chromatographic application results in a somewhat more expensive test compared to a Chlorocounter test, more accurate measurements are achieved. In addition, simultaneous measurements of sodium concentrations will result in better detection of false positives, less test repeating and thus faster and more accurate and effective diagnosis. The described IC/HPLC method, therefore, provides a precise, relatively cheap and easy-to-handle application for the analysis of both chloride and sodium in sweat. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Aircraft MSS data registration and vegetation classification of wetland change detection

USGS Publications Warehouse

Christensen, E.J.; Jensen, J.R.; Ramsey, Elijah W.; Mackey, H.E.

1988-01-01

Portions of the Savannah River floodplain swamp were evaluated for vegetation change using high resolution (5a??6 m) aircraft multispectral scanner (MSS) data. Image distortion from aircraft movement prevented precise image-to-image registration in some areas. However, when small scenes were used (200-250 ha), a first-order linear transformation provided registration accuracies of less than or equal to one pixel. A larger area was registered using a piecewise linear method. Five major wetland classes were identified and evaluated for change. Phenological differences and the variable distribution of vegetation limited wetland type discrimination. Using unsupervised methods and ground-collected vegetation data, overall classification accuracies ranged from 84 per cent to 87 per cent for each scene. Results suggest that high-resolution aircraft MSS data can be precisely registered, if small areas are used, and that wetland vegetation change can be accurately detected and monitored.

Third party EPID with IGRT capability retrofitted onto an existing medical linear accelerator

PubMed Central

Odero, DO; Shimm, DS

2009-01-01

Radiation therapy requires precision to avoid unintended irradiation of normal organs. Electronic Portal Imaging Devices (EPIDs), can help with precise patient positioning for accurate treatment. EPIDs are now bundled with new linear accelerators, or they can be purchased from the Linac manufacturer for retrofit. Retrofitting a third party EPID to a linear accelerator can pose challenges. The authors describe a relatively inexpensive third party CCD camera-based EPID manufactured by TheraView (Cablon Medical B.V.), installed onto a Siemens Primus linear accelerator, and integrated with a Lantis record and verify system, an Oldelft simulator with Digital Therapy Imaging (DTI) unit, and a Philips ADAC Pinnacle treatment planning system (TPS). This system integrates well with existing equipment and its software can process DICOM images from other sources. The system provides a complete imaging system that eliminates the need for separate software for portal image viewing, interpretation, analysis, archiving, image guided radiation therapy and other image management applications. It can also be accessed remotely via safe VPN tunnels. TheraView EPID retrofit therefore presents an example of a less expensive alternative to linear accelerator manufacturers’ proprietary EPIDs suitable for implementation in third world countries radiation therapy departments which are often faced with limited financial resources. PMID:21611056

Third party EPID with IGRT capability retrofitted onto an existing medical linear accelerator.

PubMed

Odero, D O; Shimm, D S

2009-07-01

Radiation therapy requires precision to avoid unintended irradiation of normal organs. Electronic Portal Imaging Devices (EPIDs), can help with precise patient positioning for accurate treatment. EPIDs are now bundled with new linear accelerators, or they can be purchased from the Linac manufacturer for retrofit. Retrofitting a third party EPID to a linear accelerator can pose challenges. The authors describe a relatively inexpensive third party CCD camera-based EPID manufactured by TheraView (Cablon Medical B.V.), installed onto a Siemens Primus linear accelerator, and integrated with a Lantis record and verify system, an Oldelft simulator with Digital Therapy Imaging (DTI) unit, and a Philips ADAC Pinnacle treatment planning system (TPS). This system integrates well with existing equipment and its software can process DICOM images from other sources. The system provides a complete imaging system that eliminates the need for separate software for portal image viewing, interpretation, analysis, archiving, image guided radiation therapy and other image management applications. It can also be accessed remotely via safe VPN tunnels. TheraView EPID retrofit therefore presents an example of a less expensive alternative to linear accelerator manufacturers' proprietary EPIDs suitable for implementation in third world countries radiation therapy departments which are often faced with limited financial resources.

Determination of Bosentan in Pharmaceutical Preparations by Linear Sweep, Square Wave and Differential Pulse Voltammetry Methods

PubMed Central

Atila, Alptug; Yilmaz, Bilal

2015-01-01

In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of bosentan in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of bosentan at platinum electrode in acetonitrile solution containing 0.1 M TBACIO4. The well-defined oxidation peak was observed at 1.21 V. The calibration curves were linear for bosentan at the concentration range of 5-40 µg/mL for LSV and 5-35 µg/mL for SWV and DPV methods, respectively. Intra- and inter-day precision values for bosentan were less than 4.92, and accuracy (relative error) was better than 6.29%. The mean recovery of bosentan was 100.7% for pharmaceutical preparations. No interference was found from two tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Tracleer and Diamond tablets as pharmaceutical preparation. PMID:25901151

Validated modified Lycopodium spore method development for standardisation of ingredients of an ayurvedic powdered formulation Shatavaryadi churna.

PubMed

Kumar, Puspendra; Jha, Shivesh; Naved, Tanveer

2013-01-01

Validated modified lycopodium spore method has been developed for simple and rapid quantification of herbal powdered drugs. Lycopodium spore method was performed on ingredients of Shatavaryadi churna, an ayurvedic formulation used as immunomodulator, galactagogue, aphrodisiac and rejuvenator. Estimation of diagnostic characters of each ingredient of Shatavaryadi churna individually was carried out. Microscopic determination, counting of identifying number, measurement of area, length and breadth of identifying characters were performed using Leica DMLS-2 microscope. The method was validated for intraday precision, linearity, specificity, repeatability, accuracy and system suitability, respectively. The method is simple, precise, sensitive, and accurate, and can be used for routine standardisation of raw materials of herbal drugs. This method gives the ratio of individual ingredients in the powdered drug so that any adulteration of genuine drug with its adulterant can be found out. The method shows very good linearity value between 0.988-0.999 for number of identifying character and area of identifying character. Percentage purity of the sample drug can be determined by using the linear equation of standard genuine drug.

Determination of bosentan in pharmaceutical preparations by linear sweep, square wave and differential pulse voltammetry methods.

PubMed

Atila, Alptug; Yilmaz, Bilal

2015-01-01

In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of bosentan in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of bosentan at platinum electrode in acetonitrile solution containing 0.1 M TBACIO4. The well-defined oxidation peak was observed at 1.21 V. The calibration curves were linear for bosentan at the concentration range of 5-40 µg/mL for LSV and 5-35 µg/mL for SWV and DPV methods, respectively. Intra- and inter-day precision values for bosentan were less than 4.92, and accuracy (relative error) was better than 6.29%. The mean recovery of bosentan was 100.7% for pharmaceutical preparations. No interference was found from two tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Tracleer and Diamond tablets as pharmaceutical preparation.

Heterodyne interferometry method for calibration of a Soleil-Babinet compensator.

PubMed

Zhang, Wenjing; Zhang, Zhiwei

2016-05-20

A method based on the common-path heterodyne interferometer system is proposed for the calibration of a Soleil-Babinet compensator. In this heterodyne interferometer system, which consists of two acousto-optic modulators, the compensator being calibrated is inserted into the signal path. By using the reference beam as the benchmark and a lock-in amplifier (SR844) as the phase retardation collector, retardations of 0 and λ (one wavelength) can be located accurately, and an arbitrary retardation between 0 and λ can also be measured accurately and continuously. By fitting a straight line to the experimental data, we obtained a linear correlation coefficient (R) of 0.995, which indicates that this system is capable of linear phase detection. The experimental results demonstrate determination accuracies of 0.212° and 0.26° and measurement precisions of 0.054° and 0.608° for retardations of 0 and λ, respectively.

Magnetic resonance imaging for precise radiotherapy of small laboratory animals.

PubMed

Frenzel, Thorsten; Kaul, Michael Gerhard; Ernst, Thomas Michael; Salamon, Johannes; Jäckel, Maria; Schumacher, Udo; Krüll, Andreas

2017-03-01

Radiotherapy of small laboratory animals (SLA) is often not as precisely applied as in humans. Here we describe the use of a dedicated SLA magnetic resonance imaging (MRI) scanner for precise tumor volumetry, radiotherapy treatment planning, and diagnostic imaging in order to make the experiments more accurate. Different human cancer cells were injected at the lower trunk of pfp/rag2 and SCID mice to allow for local tumor growth. Data from cross sectional MRI scans were transferred to a clinical treatment planning system (TPS) for humans. Manual palpation of the tumor size was compared with calculated tumor size of the TPS and with tumor weight at necropsy. As a feasibility study MRI based treatment plans were calculated for a clinical 6MV linear accelerator using a micro multileaf collimator (μMLC). In addition, diagnostic MRI scans were used to investigate animals which did clinical poorly during the study. MRI is superior in precise tumor volume definition whereas manual palpation underestimates their size. Cross sectional MRI allow for treatment planning so that conformal irradiation of mice with a clinical linear accelerator using a μMLC is in principle feasible. Several internal pathologies were detected during the experiment using the dedicated scanner. MRI is a key technology for precise radiotherapy of SLA. The scanning protocols provided are suited for tumor volumetry, treatment planning, and diagnostic imaging. Copyright © 2016. Published by Elsevier GmbH.

Validation of an assay for quantification of free normetanephrine, metanephrine and methoxytyramine in plasma by high performance liquid chromatography with coulometric detection: Comparison of peak-area vs. peak-height measurements.

PubMed

Nieć, Dawid; Kunicki, Paweł K

2015-10-01

Measurements of plasma concentrations of free normetanephrine (NMN), metanephrine (MN) and methoxytyramine (MTY) constitute the most diagnostically accurate screening test for pheochromocytomas and paragangliomas. The aim of this article is to present the results from a validation of an analytical method utilizing high performance liquid chromatography with coulometric detection (HPLC-CD) for quantifying plasma free NMN, MN and MTY. Additionally, peak integration by height and area and the use of one calibration curve for all batches or individual calibration curve for each batch of samples was explored as to determine the optimal approach with regard to accuracy and precision. The method was validated using charcoal stripped plasma spiked with solutions of NMN, MN, MTY and internal standard (4-hydroxy-3-methoxybenzylamine) with the exception of selectivity which was evaluated by analysis of real plasma samples. Calibration curve performance, accuracy, precision and recovery were determined following both peak-area and peak-height measurements and the obtained results were compared. The most accurate and precise method of calibration was evaluated by analyzing quality control samples at three concentration levels in 30 analytical runs. The detector response was linear over the entire tested concentration range from 10 to 2000pg/mL with R(2)≥0.9988. The LLOQ was 10pg/mL for each analyte of interest. To improve accuracy for measurements at low concentrations, a weighted (1/amount) linear regression model was employed, which resulted in inaccuracies of -2.48 to 9.78% and 0.22 to 7.81% following peak-area and peak-height integration, respectively. The imprecisions ranged from 1.07 to 15.45% and from 0.70 to 11.65% for peak-area and peak-height measurements, respectively. The optimal approach to calibration was the one utilizing an individual calibration curve for each batch of samples and peak-height measurements. It was characterized by inaccuracies ranging from -3.39 to +3.27% and imprecisions from 2.17 to 13.57%. The established HPLC-CD method enables accurate and precise measurements of plasma free NMN, MN and MTY with reasonable selectivity. Preparing calibration curve based on peak-height measurements for each batch of samples yields optimal accuracy and precision. Copyright © 2015. Published by Elsevier B.V.

Pink-Beam, Highly-Accurate Compact Water Cooled Slits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyndaker, Aaron; Deyhim, Alex; Jayne, Richard

2007-01-19

Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Elementmore » Analysis of the system are presented.« less

Bit-Grooming: Shave Your Bits with Razor-sharp Precision

NASA Astrophysics Data System (ADS)

Zender, C. S.; Silver, J.

2017-12-01

Lossless compression can reduce climate data storage by 30-40%. Further reduction requires lossy compression that also reduces precision. Fortunately, geoscientific models and measurements generate false precision (scientifically meaningless data bits) that can be eliminated without sacrificing scientifically meaningful data. We introduce Bit Grooming, a lossy compression algorithm that removes the bloat due to false-precision, those bits and bytes beyond the meaningful precision of the data.Bit Grooming is statistically unbiased, applies to all floating point numbers, and is easy to use. Bit-Grooming reduces geoscience data storage requirements by 40-80%. We compared Bit Grooming to competitors Linear Packing, Layer Packing, and GRIB2/JPEG2000. The other compression methods have the edge in terms of compression, but Bit Grooming is the most accurate and certainly the most usable and portable.Bit Grooming provides flexible and well-balanced solutions to the trade-offs among compression, accuracy, and usability required by lossy compression. Geoscientists could reduce their long term storage costs, and show leadership in the elimination of false precision, by adopting Bit Grooming.

Simultaneous determination of some cholesterol-lowering drugs in their binary mixture by novel spectrophotometric methods

NASA Astrophysics Data System (ADS)

Lotfy, Hayam Mahmoud; Hegazy, Maha Abdel Monem

2013-09-01

Four simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of simvastatin (SM) and ezetimibe (EZ) namely; extended ratio subtraction (EXRSM), simultaneous ratio subtraction (SRSM), ratio difference (RDSM) and absorption factor (AFM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated and the specificity was assessed by analyzing synthetic mixtures containing the cited drugs. The four methods were applied for the determination of the cited drugs in tablets and the obtained results were statistically compared with each other and with those of a reported HPLC method. The comparison showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

A validated ultra high-pressure liquid chromatography method for separation of candesartan cilexetil impurities and its degradents in drug product

PubMed Central

Kumar, Namala Durga Atchuta; Babu, K. Sudhakar; Gosada, Ullas; Sharma, Nitish

2012-01-01

Introduction: A selective, specific, and sensitive “Ultra High-Pressure Liquid Chromatography” (UPLC) method was developed for determination of candesartan cilexetil impurities as well asits degradent in tablet formulation. Materials and Methods: The chromatographic separation was performed on Waters Acquity UPLC system and BEH Shield RP18 column using gradient elution of mobile phase A and B. 0.01 M phosphate buffer adjusted pH 3.0 with Orthophosphoric acid was used as mobile phase A and 95% acetonitrile with 5% Milli Q Water was used as mobile phase B. Ultraviolet (UV) detection was performed at 254 nm and 210 nm, where (CDS-6), (CDS-5), (CDS-7), (Ethyl Candesartan), (Desethyl CCX), (N-Ethyl), (CCX-1), (1 N Ethyl Oxo CCX), (2 N Ethyl Oxo CCX), (2 N Ethyl) and any unknown impurity were monitored at 254 nm wavelength, and two process-related impurities, trityl alcohol and MTE impurity, were estimated at 210 nm. Candesartan cilexetil andimpurities were chromatographed with a total run time of 20 min. Results: Calibration showed that the response of impurity was a linear function of concentration over the range limit of quantification to 2 μg/mL (r2≥0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, percentage relative standard deviation of each impurity was <15% (n=6). Conclusion: The method was found to be precise, accurate, linear, and specific. The proposed method was successfully employed for estimation of candesartan cilexetil impurities in pharmaceutical preparations. PMID:23781475

Predicting the Maximum Dynamic Strength in Bench Press: The High Precision of the Bar Velocity Approach.

PubMed

Loturco, Irineu; Kobal, Ronaldo; Moraes, José E; Kitamura, Katia; Cal Abad, César C; Pereira, Lucas A; Nakamura, Fábio Y

2017-04-01

Loturco, I, Kobal, R, Moraes, JE, Kitamura, K, Cal Abad, CC, Pereira, LA, and Nakamura, FY. Predicting the maximum dynamic strength in bench press: the high precision of the bar velocity approach. J Strength Cond Res 31(4): 1127-1131, 2017-The aim of this study was to determine the force-velocity relationship and test the possibility of determining the 1 repetition maximum (1RM) in "free weight" and Smith machine bench presses. Thirty-six male top-level athletes from 3 different sports were submitted to a standardized 1RM bench press assessment (free weight or Smith machine, in randomized order), following standard procedures encompassing lifts performed at 40-100% of 1RM. The mean propulsive velocity (MPV) was measured in all attempts. A linear regression was performed to establish the relationships between bar velocities and 1RM percentages. The actual and predicted 1RM for each exercise were compared using a paired t-test. Although the Smith machine 1RM was higher (10% difference) than the free weight 1RM, in both cases the actual and predicted values did not differ. In addition, the linear relationship between MPV and percentage of 1RM (coefficient of determination ≥95%) allow determination of training intensity based on the bar velocity. The linear relationships between the MPVs and the relative percentages of 1RM throughout the entire range of loads enable coaches to use the MPV to accurately monitor their athletes on a daily basis and accurately determine their actual 1RM without the need to perform standard maximum dynamic strength assessments.

Pricise Target Geolocation Based on Integeration of Thermal Video Imagery and Rtk GPS in Uavs

NASA Astrophysics Data System (ADS)

Hosseinpoor, H. R.; Samadzadegan, F.; Dadras Javan, F.

2015-12-01

There are an increasingly large number of uses for Unmanned Aerial Vehicles (UAVs) from surveillance, mapping and target geolocation. However, most of commercial UAVs are equipped with low-cost navigation sensors such as C/A code GPS and a low-cost IMU on board, allowing a positioning accuracy of 5 to 10 meters. This low accuracy which implicates that it cannot be used in applications that require high precision data on cm-level. This paper presents a precise process for geolocation of ground targets based on thermal video imagery acquired by small UAV equipped with RTK GPS. The geolocation data is filtered using a linear Kalman filter, which provides a smoothed estimate of target location and target velocity. The accurate geo-locating of targets during image acquisition is conducted via traditional photogrammetric bundle adjustment equations using accurate exterior parameters achieved by on board IMU and RTK GPS sensors and Kalman filtering and interior orientation parameters of thermal camera from pre-flight laboratory calibration process.

Development of a compact, fiber-coupled, six degree-of-freedom measurement system for precision linear stage metrology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xiangzhi, E-mail: xiangzhi.yu@rochester.edu; Gillmer, Steven R.; Woody, Shane C.

2016-06-15

A compact, fiber-coupled, six degree-of-freedom measurement system which enables fast, accurate calibration, and error mapping of precision linear stages is presented. The novel design has the advantages of simplicity, compactness, and relatively low cost. This proposed sensor can simultaneously measure displacement, two straightness errors, and changes in pitch, yaw, and roll using a single optical beam traveling between the measurement system and a small target. The optical configuration of the system and the working principle for all degrees-of-freedom are presented along with the influence and compensation of crosstalk motions in roll and straightness measurements. Several comparison experiments are conducted tomore » investigate the feasibility and performance of the proposed system in each degree-of-freedom independently. Comparison experiments to a commercial interferometer demonstrate error standard deviations of 0.33 μm in straightness, 0.14 μrad in pitch, 0.44 μradin yaw, and 45.8 μrad in roll.« less

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves.

PubMed

Katekhaye, S; Kale, M S; Laddha, K S

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C(18) column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r(2)>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves.

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves

PubMed Central

Katekhaye, S; Kale, M. S.; Laddha, K. S.

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C18 column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r2>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves. PMID:23204626

Development and Validation of RP-LC Method for the Determination of Cinnarizine/Piracetam and Cinnarizine/Heptaminol Acefyllinate in Presence of Cinnarizine Reported Degradation Products

PubMed Central

EL-Houssini, Ola M.; Zawilla, Nagwan H.; Mohammad, Mohammad A.

2013-01-01

Specific stability indicating reverse-phase liquid chromatography (RP-LC) assay method (SIAM) was developed for the determination of cinnarizine (Cinn)/piracetam (Pira) and cinnarizine (Cinn)/heptaminol acefyllinate (Hept) in the presence of the reported degradation products of Cinn. A C18 column and gradient mobile phase was applied for good resolution of all peaks. The detection was achieved at 210 nm and 254 nm for Cinn/Pira and Cinn/Hept, respectively. The responses were linear over concentration ranges of 20–200, 20–1000 and 25–1000 μgmL−1 for Cinn, Pira, and Hept respectively. The proposed method was validated for linearity, accuracy, repeatability, intermediate precision, and robustness via statistical analysis of the data. The method was shown to be precise, accurate, reproducible, sensitive, and selective for the analysis of Cinn/Pira and Cinn/Hept in laboratory prepared mixtures and in pharmaceutical formulations. PMID:24137049

High Accuracy Passive Magnetic Field-Based Localization for Feedback Control Using Principal Component Analysis.

PubMed

Foong, Shaohui; Sun, Zhenglong

2016-08-12

In this paper, a novel magnetic field-based sensing system employing statistically optimized concurrent multiple sensor outputs for precise field-position association and localization is presented. This method capitalizes on the independence between simultaneous spatial field measurements at multiple locations to induce unique correspondences between field and position. This single-source-multi-sensor configuration is able to achieve accurate and precise localization and tracking of translational motion without contact over large travel distances for feedback control. Principal component analysis (PCA) is used as a pseudo-linear filter to optimally reduce the dimensions of the multi-sensor output space for computationally efficient field-position mapping with artificial neural networks (ANNs). Numerical simulations are employed to investigate the effects of geometric parameters and Gaussian noise corruption on PCA assisted ANN mapping performance. Using a 9-sensor network, the sensing accuracy and closed-loop tracking performance of the proposed optimal field-based sensing system is experimentally evaluated on a linear actuator with a significantly more expensive optical encoder as a comparison.

Determination of three steroidal saponins from Ophiopogon japonicus (Liliaceae) via high-performance liquid chromatography with mass spectrometry.

PubMed

Wang, Yongyi; Xu, Jinzhong; Qu, Haibin

2013-01-01

A simple and accurate analytical method was developed for simultaneous quantification of three steroidal saponins in the roots of Ophiopogon japonicus via high-performance liquid chromatography (HPLC) with mass spectrometry (MS) in this study. Separation was performed on a Tigerkin C(18) column and detection was performed by mass spectrometry. A mobile phase consisted of 0.02% formic acid in water (v/v) and 0.02% formic acid in acetonitrile (v/v) was used with a flow rate of 0.5 mL min(-1). The quantitative HPLC-MS method was validated for linearity, precision, repeatability, stability, recovery, limits of detection and quantification. This developed method provides good linearity (r >0.9993), intra- and inter-day precisions (RSD <4.18%), repeatability (RSD <5.05%), stability (RSD <2.08%) and recovery (93.82-102.84%) for three steroidal saponins. It could be considered as a suitable quality control method for O. japonicus.

Numerical investigation of multi-beam laser heterodyne measurement with ultra-precision for linear expansion coefficient of metal based on oscillating mirror modulation

NASA Astrophysics Data System (ADS)

Li, Yan-Chao; Wang, Chun-Hui; Qu, Yang; Gao, Long; Cong, Hai-Fang; Yang, Yan-Ling; Gao, Jie; Wang, Ao-You

2011-01-01

This paper proposes a novel method of multi-beam laser heterodyne measurement for metal linear expansion coefficient. Based on the Doppler effect and heterodyne technology, the information is loaded of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by temperature variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain the value of linear expansion coefficient of metal by the calculation. This novel method is used to simulate measurement for linear expansion coefficient of metal rod under different temperatures by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.4%.

Characterization of a signal recording system for accurate velocity estimation using a VISAR

NASA Astrophysics Data System (ADS)

Rav, Amit; Joshi, K. D.; Singh, Kulbhushan; Kaushik, T. C.

2018-02-01

The linearity of a signal recording system (SRS) in time as well as in amplitude are important for the accurate estimation of the free surface velocity history of a moving target during shock loading and unloading when measured using optical interferometers such as a velocity interferometer system for any reflector (VISAR). Signal recording being the first step in a long sequence of signal processes, the incorporation of errors due to nonlinearity, and low signal-to-noise ratio (SNR) affects the overall accuracy and precision of the estimation of velocity history. In shock experiments the small duration (a few µs) of loading/unloading, the reflectivity of moving target surface, and the properties of optical components, control the amount of input of light to the SRS of a VISAR and this in turn affects the linearity and SNR of the overall measurement. These factors make it essential to develop in situ procedures for (i) minimizing the effect of signal induced noise and (ii) determine the linear region of operation for the SRS. Here we report on a procedure for the optimization of SRS parameters such as photodetector gain, optical power, aperture etc, so as to achieve a linear region of operation with a high SNR. The linear region of operation so determined has been utilized successfully to estimate the temporal history of the free surface velocity of the moving target in shock experiments.

Simultaneous determination of related substances of telmisartan and hydrochlorothiazide in tablet dosage form by using reversed phase high performance liquid chromatographic method

PubMed Central

Mukhopadhyay, Sutirtho; Kadam, Kiran; Sawant, Laxman; Nachane, Dhanashree; Pandita, Nancy

2011-01-01

Objective: Telmisartan is a potent, long-lasting, nonpeptide antagonist of the angiotensin II type-1 (AT1) receptor that is indicated for the treatment of essential hypertension. Hydrochlorothiazide is a widely prescribed diuretic and it is indicated for the treatment of edema, control of essential hypertension and management of diabetes insipidus. In the current article a new, accurate, sensitive, precise, rapid, reversed phase high performance liquid chromatography (RP-HPLC) method was developed for determination of related substances of Telmisartan and Hydrochlorthiazide in tablet dosage form. Materials and Methods: Simultaneous determination of related substances was performed on Kromasil C18 analytical column (250 × 4.6 mm; 5μm pertical size) column at 40°C employing a gradient elution. Mobile phase consisting of solvent A (solution containing 2.0 g of potassium dihydrogen phosphate anhydrous and 1.04 g of Sodium 1- Hexane sulphonic acid monohydrate per liter of water, adjusted to pH 3.0 with orthophosphoric acid) and solvent B (mixture of Acetonitrile: Methanol in the ratio 80:20 v/v) was used at a flow rate of 1.0 ml min–1. UV detection was performed at 270 nm. Results: During method validation parameter such as precision, linearity, accuracy, specificity, limit of detection and quantification were evaluated, which remained within acceptable limits. Conclusions: HPLC analytical method is linear, accurate, precise, robust and specific, being able to separate the main drug from its degradation products. It may find application for the routine analysis of the related substances of both Telmisartan and Hydrochlorthiazide in this combination tablets. PMID:21966158

[Variable selection methods combined with local linear embedding theory used for optimization of near infrared spectral quantitative models].

PubMed

Hao, Yong; Sun, Xu-Dong; Yang, Qiang

2012-12-01

Variables selection strategy combined with local linear embedding (LLE) was introduced for the analysis of complex samples by using near infrared spectroscopy (NIRS). Three methods include Monte Carlo uninformation variable elimination (MCUVE), successive projections algorithm (SPA) and MCUVE connected with SPA were used for eliminating redundancy spectral variables. Partial least squares regression (PLSR) and LLE-PLSR were used for modeling complex samples. The results shown that MCUVE can both extract effective informative variables and improve the precision of models. Compared with PLSR models, LLE-PLSR models can achieve more accurate analysis results. MCUVE combined with LLE-PLSR is an effective modeling method for NIRS quantitative analysis.

A Revolute Joint With Linear Load-Displacement Response for Precision Deployable Structures

NASA Technical Reports Server (NTRS)

Lake, Mark S.; Warren, Peter A.; Peterson, Lee D.

1996-01-01

NASA Langley Research center is developing key structures and mechanisms technologies for micron-accuracy, in-space deployment of future space instruments. Achieving micron-accuracy deployment requires significant advancements in deployment mechanism design such as the revolute joint presented herein. The joint presented herein exhibits a load-cycling response that is essentially linear with less than two percent hysteresis, and the joint rotates with less than one in.-oz. of resistance. A prototype reflector metering truss incorporating the joint exhibits only a few microns of kinematic error under repeated deployment and impulse loading. No other mechanically deployable structure found in literature has been demonstrated to be this kinematically accurate.

Extraction and LC determination of lysine clonixinate salt in water/oil microemulsions.

PubMed

Pineros, I; Ballesteros, P; Lastres, J L

2002-02-01

A new reversed-phase high performance liquid chromatography method has been developed and validated for the quantitative determination of lysine clonixinate salt in water/oil microemulsions. The mobile phase was acetonitrile-buffer phosphate pH 3.3. Detection was UV absorbance at 252 nm. The precision and accurately of the method were excellent. The established linearity range was 5-60 microg ml(-1) (r(2)=0.999). Microemulsions samples were dispersed with chloroform and extracted lysine clonixinate salt with water. This easy method employing chloroformic extraction has been done three times. The recovery of lysine clonixinate salt from spiked placebo and microemulsion were >90% over the linear range.

Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space.

PubMed

Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J

2013-01-01

Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies.

Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space

PubMed Central

Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J.

2013-01-01

Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies. PMID:24156059

Simultaneous Determination of Potassium Clavulanate and Amoxicillin Trihydrate in Bulk, Pharmaceutical Formulations and in Human Urine Samples by UV Spectrophotometry

PubMed Central

Gujral, Rajinder Singh; Haque, Sk Manirul

2010-01-01

A simple and sensitive UV spectrophotometric method was developed and validated for the simultaneous determination of Potassium Clavulanate (PC) and Amoxicillin Trihydrate (AT) in bulk, pharmaceutical formulations and in human urine samples. The method was linear in the range of 0.2–8.5 μg/ml for PC and 6.4–33.6 μg/ml for AT. The absorbance was measured at 205 and 271 nm for PC and AT respectively. The method was validated with respect to accuracy, precision, specificity, ruggedness, robustness, limit of detection and limit of quantitation. This method was used successfully for the quality assessment of four PC and AT drug products and in human urine samples with good precision and accuracy. This is found to be simple, specific, precise, accurate, reproducible and low cost UV Spectrophotometric method. PMID:23675211

An eclipsing-binary distance to the Large Magellanic Cloud accurate to two per cent.

PubMed

Pietrzyński, G; Graczyk, D; Gieren, W; Thompson, I B; Pilecki, B; Udalski, A; Soszyński, I; Kozłowski, S; Konorski, P; Suchomska, K; Bono, G; Moroni, P G Prada; Villanova, S; Nardetto, N; Bresolin, F; Kudritzki, R P; Storm, J; Gallenne, A; Smolec, R; Minniti, D; Kubiak, M; Szymański, M K; Poleski, R; Wyrzykowski, L; Ulaczyk, K; Pietrukowicz, P; Górski, M; Karczmarek, P

2013-03-07

In the era of precision cosmology, it is essential to determine the Hubble constant to an accuracy of three per cent or better. At present, its uncertainty is dominated by the uncertainty in the distance to the Large Magellanic Cloud (LMC), which, being our second-closest galaxy, serves as the best anchor point for the cosmic distance scale. Observations of eclipsing binaries offer a unique opportunity to measure stellar parameters and distances precisely and accurately. The eclipsing-binary method was previously applied to the LMC, but the accuracy of the distance results was lessened by the need to model the bright, early-type systems used in those studies. Here we report determinations of the distances to eight long-period, late-type eclipsing systems in the LMC, composed of cool, giant stars. For these systems, we can accurately measure both the linear and the angular sizes of their components and avoid the most important problems related to the hot, early-type systems. The LMC distance that we derive from these systems (49.97 ± 0.19 (statistical) ± 1.11 (systematic) kiloparsecs) is accurate to 2.2 per cent and provides a firm base for a 3-per-cent determination of the Hubble constant, with prospects for improvement to 2 per cent in the future.

[Determination of trace cobalt in human urine by graphite furnace atomic absorption spectrometr].

PubMed

Zhong, L X; Ding, B M; Jiang, D; Liu, D Y; Yu, B; Zhu, B L; Ding, L

2016-05-20

To establish a method to determine cobalt in human urine by graphite furnace atomic absorption spectrometry. Urine with 2% nitric acid diluted two-fold, to quantify the curve, graphite furnace atomic absorption spectrometric detection. Co was linear within 2.5~40.0 ng/ml with r>0.999. Spike experiment showed that Co received good recovery rate, which was 90.8%~94.8%. Intra-assay precisions were 3.2%~5.1% for Co, inter-assay precisions were 4.4%~5.2% for Co. The method by using graphite furnace atomic absorption spectrometr to determine urine Co was fast, accurate and with low matrix effect. It could meet the requirement in GBZ/T 210.5-2008.

Estimation of stature using anthropometry of feet and footprints in a Western Australian population.

PubMed

Hemy, Naomi; Flavel, Ambika; Ishak, Nur-Intaniah; Franklin, Daniel

2013-07-01

The aim of the study is to develop accurate stature estimation models for a contemporary Western Australian population from measurements of the feet and footprints. The sample comprises 200 adults (90 males, 110 females). A stature measurement, three linear measurements from each foot and bilateral footprints were collected from each subject. Seven linear measurements were then extracted from each print. Prior to data collection, a precision test was conducted to determine the repeatability of measurement acquisition. The primary data were then analysed using a range of parametric statistical tests. Results show that all foot and footprint measurements were significantly (P < 0.01-0.001) correlated with stature and estimation models were formulated with a prediction accuracy of ± 4.673 cm to ± 6.926 cm. Left foot length was the most accurate single variable in the simple linear regressions (males: ± 5.065 cm; females: ± 4.777 cm). This study provides viable alternatives for estimating stature in a Western Australian population that are equivalent to established standards developed from foot bones. Copyright © 2013 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

The Effects of Fabrication Techniques and Storage Methods on the Dimensional Stability of Removable Acrylic Resin Orthoses.

DTIC Science & Technology

1987-05-01

Bruxism : a report and a case report. J. Dent. Med., 9:189-199, 1954. 138. Super, S: A modified occlusal splint for segmental osteotomy fixation. J. Oral...minimize linear dimensional change prior to the clinical use of a removable acrylic resin orthosis. . .. . . . . TABLE OF CONTENTS Title...distortion and clinical use of an orthosis having a precise and accurate fit. V % N II. LITERATURE REVIEW A. Terminology The therapeutic use of interocclusal

GHM method for obtaining rationalsolutions of nonlinear differential equations.

PubMed

Vazquez-Leal, Hector; Sarmiento-Reyes, Arturo

2015-01-01

In this paper, we propose the application of the general homotopy method (GHM) to obtain rational solutions of nonlinear differential equations. It delivers a high precision representation of the nonlinear differential equation using a few linear algebraic terms. In order to assess the benefits of this proposal, three nonlinear problems are solved and compared against other semi-analytic methods or numerical methods. The obtained results show that GHM is a powerful tool, capable to generate highly accurate rational solutions. AMS subject classification 34L30.

Theoretical and experimental research on machine tool servo system for ultra-precision position compensation on CNC lathe

NASA Astrophysics Data System (ADS)

Ma, Zhichao; Hu, Leilei; Zhao, Hongwei; Wu, Boda; Peng, Zhenxing; Zhou, Xiaoqin; Zhang, Hongguo; Zhu, Shuai; Xing, Lifeng; Hu, Huang

2010-08-01

The theories and techniques for improving machining accuracy via position control of diamond tool's tip and raising resolution of cutting depth on precise CNC lathes have been extremely focused on. A new piezo-driven ultra-precision machine tool servo system is designed and tested to improve manufacturing accuracy of workpiece. The mathematical model of machine tool servo system is established and the finite element analysis is carried out on parallel plate flexure hinges. The output position of diamond tool's tip driven by the machine tool servo system is tested via a contact capacitive displacement sensor. Proportional, integral, derivative (PID) feedback is also implemented to accommodate and compensate dynamical change owing cutting forces as well as the inherent non-linearity factors of the piezoelectric stack during cutting process. By closed loop feedback controlling strategy, the tracking error is limited to 0.8 μm. Experimental results have shown the proposed machine tool servo system could provide a tool positioning resolution of 12 nm, which is much accurate than the inherent CNC resolution magnitude. The stepped shaft of aluminum specimen with a step increment of cutting depth of 1 μm is tested, and the obtained contour illustrates the displacement command output from controller is accurately and real-time reflected on the machined part.

An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

NASA Astrophysics Data System (ADS)

Obersteiner, F.; Bönisch, H.; Engel, A.

2016-01-01

We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. Detector non-linearity was found to be insignificant up to a mixing ratio of roughly 150 ppt at 0.5 L sampled volume. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straightforward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, quadrupole MS with low mass resolving power and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

Linear FMCW Laser Radar for Precision Range and Vector Velocity Measurements

NASA Technical Reports Server (NTRS)

Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockhard, George; Rubio, Manuel

2008-01-01

An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA s new Space Exploration initiative for manned and robotic missions to the Moon and Mars. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed. Linear FMCW lidar has the capability of high-resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision horizontal and vertical velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the preselected site and achieving autonomous, safe soft-landing. The all-fiber coherent laser radar has several important advantages over more conventional pulsed laser altimeters or range finders. One of the advantages of the coherent laser radar is its ability to measure directly the platform velocity by extracting the Doppler shift generated from the motion, as opposed to time of flight range finders where terrain features such as hills, cliffs, or slopes add error to the velocity measurement. Doppler measurements are about two orders of magnitude more accurate than the velocity estimates obtained by pulsed laser altimeters. In addition, most of the components of the device are efficient and reliable commercial off-the-shelf fiber optic telecommunication components. This paper discusses the design and performance of a second-generation brassboard system under development at NASA Langley Research Center as part of the Autonomous Landing and Hazard Avoidance (ALHAT) project.

Simultaneous Determination of Crypto-Chlorogenic Acid, Isoquercetin, and Astragalin Contents in Moringa oleifera Leaf Extracts by TLC-Densitometric Method.

PubMed

Vongsak, Boonyadist; Sithisarn, Pongtip; Gritsanapan, Wandee

2013-01-01

Moringa oleifera Lamarck (Moringaceae) is used as a multipurpose medicinal plant for the treatment of various diseases. Isoquercetin, astragalin, and crypto-chlorogenic acid have been previously found to be major active components in the leaves of this plant. In this study, a thin-layer-chromatography (TLC-)densitometric method was developed and validated for simultaneous quantification of these major components in the 70% ethanolic extracts of M. oleifera leaves collected from 12 locations. The average amounts of crypto-chlorogenic acid, isoquercetin, and astragalin were found to be 0.0473, 0.0427, and 0.0534% dry weight, respectively. The method was validated for linearity, precision, accuracy, limit of detection, limit of quantitation, and robustness. The linearity was obtained in the range of 100-500 ng/spot with a correlation coefficient (r) over 0.9961. Intraday and interday precisions demonstrated relative standard deviations of less than 5%. The accuracy of the method was confirmed by determining the recovery. The average recoveries of each component from the extracts were in the range of 98.28 to 99.65%. Additionally, the leaves from Chiang Mai province contained the highest amounts of all active components. The proposed TLC-densitometric method was simple, accurate, precise, and cost-effective for routine quality controlling of M. oleifera leaf extracts.

Research on a high-precision calibration method for tunable lasers

NASA Astrophysics Data System (ADS)

Xiang, Na; Li, Zhengying; Gui, Xin; Wang, Fan; Hou, Yarong; Wang, Honghai

2018-03-01

Tunable lasers are widely used in the field of optical fiber sensing, but nonlinear tuning exists even for zero external disturbance and limits the accuracy of the demodulation. In this paper, a high-precision calibration method for tunable lasers is proposed. A comb filter is introduced and the real-time output wavelength and scanning rate of the laser are calibrated by linear fitting several time-frequency reference points obtained from it, while the beat signal generated by the auxiliary interferometer is interpolated and frequency multiplied to find more accurate zero crossing points, with these points being used as wavelength counters to resample the comb signal to correct the nonlinear effect, which ensures that the time-frequency reference points of the comb filter are linear. A stability experiment and a strain sensing experiment verify the calibration precision of this method. The experimental result shows that the stability and wavelength resolution of the FBG demodulation can reach 0.088 pm and 0.030 pm, respectively, using a tunable laser calibrated by the proposed method. We have also compared the demodulation accuracy in the presence or absence of the comb filter, with the result showing that the introduction of the comb filter results to a 15-fold wavelength resolution enhancement.

Validation of the sperm class analyser CASA system for sperm counting in a busy diagnostic semen analysis laboratory.

PubMed

Dearing, Chey G; Kilburn, Sally; Lindsay, Kevin S

2014-03-01

Sperm counts have been linked to several fertility outcomes making them an essential parameter of semen analysis. It has become increasingly recognised that Computer-Assisted Semen Analysis (CASA) provides improved precision over manual methods but that systems are seldom validated robustly for use. The objective of this study was to gather the evidence to validate or reject the Sperm Class Analyser (SCA) as a tool for routine sperm counting in a busy laboratory setting. The criteria examined were comparison with the Improved Neubauer and Leja 20-μm chambers, within and between field precision, sperm concentration linearity from a stock diluted in semen and media, accuracy against internal and external quality material, assessment of uneven flow effects and a receiver operating characteristic (ROC) analysis to predict fertility in comparison with the Neubauer method. This work demonstrates that SCA CASA technology is not a standalone 'black box', but rather a tool for well-trained staff that allows rapid, high-number sperm counting providing errors are identified and corrected. The system will produce accurate, linear, precise results, with less analytical variance than manual methods that correlate well against the Improved Neubauer chamber. The system provides superior predictive potential for diagnosing fertility problems.

Imaging the Iceland Hotspot Track Beneath Greenland with Seismic Noise Correlations

NASA Astrophysics Data System (ADS)

Mordret, A.

2017-12-01

During the past 65 million years, the Greenland craton drifted over the Iceland hotspot; however, uncertainties in geodynamic modeling and a lack of geophysical evidence prevent an accurate reconstruction of the hotspot track. I image the Greenland lithosphere down to 300 km depth with seismic noise tomography. The hotspot track is observed as a linear high-velocity anomaly in the middle crust associated with magmatic intrusions. In the upper mantle, the remnant thermal signature of the hotspot manifests as low velocity and low viscosity bodies. This new detailed picture of the Greenland lithosphere will drive more accurate geodynamic reconstructions of tectonic plate motions and prediction of Greenland heat flow, which in turn will enable more precise estimations of the Greenland ice-sheet mass balance.

High-performance time-resolved fluorescence by direct waveform recording.

PubMed

Muretta, Joseph M; Kyrychenko, Alexander; Ladokhin, Alexey S; Kast, David J; Gillispie, Gregory D; Thomas, David D

2010-10-01

We describe a high-performance time-resolved fluorescence (HPTRF) spectrometer that dramatically increases the rate at which precise and accurate subnanosecond-resolved fluorescence emission waveforms can be acquired in response to pulsed excitation. The key features of this instrument are an intense (1 μJ/pulse), high-repetition rate (10 kHz), and short (1 ns full width at half maximum) laser excitation source and a transient digitizer (0.125 ns per time point) that records a complete and accurate fluorescence decay curve for every laser pulse. For a typical fluorescent sample containing a few nanomoles of dye, a waveform with a signal/noise of about 100 can be acquired in response to a single laser pulse every 0.1 ms, at least 10(5) times faster than the conventional method of time-correlated single photon counting, with equal accuracy and precision in lifetime determination for lifetimes as short as 100 ps. Using standard single-lifetime samples, the detected signals are extremely reproducible, with waveform precision and linearity to within 1% error for single-pulse experiments. Waveforms acquired in 0.1 s (1000 pulses) with the HPTRF instrument were of sufficient precision to analyze two samples having different lifetimes, resolving minor components with high accuracy with respect to both lifetime and mole fraction. The instrument makes possible a new class of high-throughput time-resolved fluorescence experiments that should be especially powerful for biological applications, including transient kinetics, multidimensional fluorescence, and microplate formats.

Bit Grooming: statistically accurate precision-preserving quantization with compression, evaluated in the netCDF Operators (NCO, v4.4.8+)

NASA Astrophysics Data System (ADS)

Zender, Charles S.

2016-09-01

Geoscientific models and measurements generate false precision (scientifically meaningless data bits) that wastes storage space. False precision can mislead (by implying noise is signal) and be scientifically pointless, especially for measurements. By contrast, lossy compression can be both economical (save space) and heuristic (clarify data limitations) without compromising the scientific integrity of data. Data quantization can thus be appropriate regardless of whether space limitations are a concern. We introduce, implement, and characterize a new lossy compression scheme suitable for IEEE floating-point data. Our new Bit Grooming algorithm alternately shaves (to zero) and sets (to one) the least significant bits of consecutive values to preserve a desired precision. This is a symmetric, two-sided variant of an algorithm sometimes called Bit Shaving that quantizes values solely by zeroing bits. Our variation eliminates the artificial low bias produced by always zeroing bits, and makes Bit Grooming more suitable for arrays and multi-dimensional fields whose mean statistics are important. Bit Grooming relies on standard lossless compression to achieve the actual reduction in storage space, so we tested Bit Grooming by applying the DEFLATE compression algorithm to bit-groomed and full-precision climate data stored in netCDF3, netCDF4, HDF4, and HDF5 formats. Bit Grooming reduces the storage space required by initially uncompressed and compressed climate data by 25-80 and 5-65 %, respectively, for single-precision values (the most common case for climate data) quantized to retain 1-5 decimal digits of precision. The potential reduction is greater for double-precision datasets. When used aggressively (i.e., preserving only 1-2 digits), Bit Grooming produces storage reductions comparable to other quantization techniques such as Linear Packing. Unlike Linear Packing, whose guaranteed precision rapidly degrades within the relatively narrow dynamic range of values that it can compress, Bit Grooming guarantees the specified precision throughout the full floating-point range. Data quantization by Bit Grooming is irreversible (i.e., lossy) yet transparent, meaning that no extra processing is required by data users/readers. Hence Bit Grooming can easily reduce data storage volume without sacrificing scientific precision or imposing extra burdens on users.

Development and Validation of Liquid Chromatographic Method for Estimation of Naringin in Nanoformulation

PubMed Central

Musmade, Kranti P.; Trilok, M.; Dengale, Swapnil J.; Bhat, Krishnamurthy; Reddy, M. S.; Musmade, Prashant B.; Udupa, N.

2014-01-01

A simple, precise, accurate, rapid, and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method with UV detection has been developed and validated for quantification of naringin (NAR) in novel pharmaceutical formulation. NAR is a polyphenolic flavonoid present in most of the citrus plants having variety of pharmacological activities. Method optimization was carried out by considering the various parameters such as effect of pH and column. The analyte was separated by employing a C18 (250.0 × 4.6 mm, 5 μm) column at ambient temperature in isocratic conditions using phosphate buffer pH 3.5: acetonitrile (75 : 25% v/v) as mobile phase pumped at a flow rate of 1.0 mL/min. UV detection was carried out at 282 nm. The developed method was validated according to ICH guidelines Q2(R1). The method was found to be precise and accurate on statistical evaluation with a linearity range of 0.1 to 20.0 μg/mL for NAR. The intra- and interday precision studies showed good reproducibility with coefficients of variation (CV) less than 1.0%. The mean recovery of NAR was found to be 99.33 ± 0.16%. The proposed method was found to be highly accurate, sensitive, and robust. The proposed liquid chromatographic method was successfully employed for the routine analysis of said compound in developed novel nanopharmaceuticals. The presence of excipients did not show any interference on the determination of NAR, indicating method specificity. PMID:26556205

New Stability-Indicating RP-HPLC Method for Determination of Diclofenac Potassium and Metaxalone from their Combined Dosage Form

PubMed Central

Panda, Sagar Suman; Patanaik, Debasis; Ravi Kumar, Bera V. V.

2012-01-01

A simple, precise and accurate isocratic RP-HPLC stability-indicating assay method has been developed to determine diclofenac potassium and metaxalone in their combined dosage forms. Isocratic separation was achieved on a Hibar-C18, Lichrosphere-100® (250 mm × 4.6 mm i.d., particle size 5 μm) column at room temperature in isocratic mode, the mobile phase consists of methanol: water (80:20, v/v) at a flow rate of 1.0 ml/min, the injection volume was 20 μl and UV detection was carried out at 280nm. The drug was subjected to acid and alkali hydrolysis, oxidation, photolysis and heat as stress conditions. The method was validated for specificity, linearity, precision, accuracy, robustness and system suitability. The method was linear in the drug concentration range of 2.5–30 μg/ml and 20–240 μg/ml for diclofenac potassium and metaxalone, respectively. The precision (RSD) of six samples was 0.83 and 0.93% for repeatability, and the intermediate precision (RSD) among six-sample preparation was 1.63 and 0.49% for diclofenac potassium and metaxalone, respectively. The mean recoveries were between 100.99–102.58% and 99.97–100.01% for diclofenac potassium and metaxalone, respectively. The proposed method can be used successfully for routine analysis of the drug in bulk and combined pharmaceutical dosage forms. PMID:22396909

Practical controller design for ultra-precision positioning of stages with a pneumatic artificial muscle actuator

NASA Astrophysics Data System (ADS)

Tang, T. F.; Chong, S. H.

2017-06-01

This paper presents a practical controller design method for ultra-precision positioning of pneumatic artificial muscle actuator stages. Pneumatic artificial muscle (PAM) actuators are safe to use and have numerous advantages which have brought these actuators to wide applications. However, PAM exhibits strong non-linear characteristics, and these limitations lead to low controllability and limit its application. In practice, the non-linear characteristics of PAM mechanism are difficult to be precisely modeled, and time consuming to model them accurately. The purpose of the present study is to clarify a practical controller design method that emphasizes a simple design procedure that does not acquire plants parameters modeling, and yet is able to demonstrate ultra-precision positioning performance for a PAM driven stage. The practical control approach adopts continuous motion nominal characteristic trajectory following (CM NCTF) control as the feedback controller. The constructed PAM driven stage is in low damping characteristic and causes severe residual vibration that deteriorates motion accuracy of the system. Therefore, the idea to increase the damping characteristic by having an acceleration feedback compensation to the plant has been proposed. The effectiveness of the proposed controller was verified experimentally and compared with a classical PI controller in point-to-point motion. The experiment results proved that the CM NCTF controller demonstrates better positioning performance in smaller motion error than the PI controller. Overall, the CM NCTF controller has successfully to reduce motion error to 3µm, which is 88.7% smaller than the PI controller.

Simultaneous Determination of Soyasaponins and Isoflavones in Soy (Glycine max L.) Products by HPTLC-densitometry-Multiple Detection.

PubMed

Shawky, Eman; Sallam, Shaimaa M

2017-11-01

A new high-throughput method was developed for the simultaneous analysis of isoflavones and soyasaponnins in Soy (Glycine max L.) products by high-performance thin-layer chromatography with densitometry and multiple detection. Silica gel was used as the stationary phase and ethyl acetate:methanol:water:acetic acid (100:20:16:1, v/v/v/v) as the mobile phase. After chromatographic development, multi-wavelength scanning was carried out by: (i) UV-absorbance measurement at 265 nm for genistin, daidzin and glycitin, (ii) Vis-absorbance measurement at 650 nm for Soyasaponins I and III, after post-chromatographic derivatization with anisaldehyde/sulfuric acid reagent. Validation of the developed method was found to meet the acceptance criteria delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. Calibrations were linear with correlation coefficients of >0.994. Intra-day precisions relative standard deviation (RSD)% of all substances in matrix were determined to be between 0.7 and 0.9%, while inter-day precisions (RSD%) ranged between 1.2 and 1.8%. The validated method was successfully applied for determination of the studied analytes in soy-based infant formula and soybean products. The new method compares favorably to other reported methods in being as accurate and precise and in the same time more feasible and cost-effective. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Microbiological assay for the determination of meropenem in pharmaceutical dosage form.

PubMed

Mendez, Andreas S L; Weisheimer, Vanessa; Oppe, Tércio P; Steppe, Martin; Schapoval, Elfrides E S

2005-04-01

Meropenem is a highly active carbapenem antibiotic used in the treatment of a wide range of serious infections. The present work reports a microbiological assay, applying the cylinder-plate method, for the determination of meropenem in powder for injection. The validation method yielded good results and included linearity, precision, accuracy and specificity. The assay is based on the inhibitory effect of meropenem upon the strain of Micrococcus luteus ATCC 9341 used as the test microorganism. The results of assay were treated statistically by analysis of variance (ANOVA) and were found to be linear (r=0.9999) in the range of 1.5-6.0 microg ml(-1), precise (intra-assay: R.S.D.=0.29; inter-assay: R.S.D.=0.94) and accurate. A preliminary stability study of meropenem was performed to show that the microbiological assay is specific for the determination of meropenem in the presence of its degradation products. The degraded samples were also analysed by the HPLC method. The proposed method allows the quantitation of meropenem in pharmaceutical dosage form and can be used for the drug analysis in routine quality control.

Simultaneous Determination of Withanolide A and Bacoside A in Spansules by High-Performance Thin-Layer Chromatography

PubMed Central

Shinde, P B; Aragade, P D; Agrawal, M R; Deokate, U A; Khadabadi, S S

2011-01-01

The objective of this work was to develop and validate a simple, rapid, precise, and accurate high performance thin layer chromatography method for simultaneous determination of withanolide A and bacoside A in combined dosage form. The stationary phase used was silica gel G60F254. The mobile phase used was mixture of ethyl acetate: methanol: toluene: water (4:1:1:0.5 v/v/v/v). The detection of spots was carried out at 320 nm using absorbance reflectance mode. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 200 to 800 ng/spot for withanolide A and 50 to 350 ng/spot for bacoside A. The limit of detection and limit of quantification for the withanolide A were found to be 3.05 and 10.06 ng/spot, respectively and for bacoside A 8.3 and 27.39 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed formulation. PMID:22303073

Simultaneous determination of withanolide a and bacoside a in spansules by high-performance thin-layer chromatography.

PubMed

Shinde, P B; Aragade, P D; Agrawal, M R; Deokate, U A; Khadabadi, S S

2011-03-01

The objective of this work was to develop and validate a simple, rapid, precise, and accurate high performance thin layer chromatography method for simultaneous determination of withanolide A and bacoside A in combined dosage form. The stationary phase used was silica gel G60F(254). The mobile phase used was mixture of ethyl acetate: methanol: toluene: water (4:1:1:0.5 v/v/v/v). The detection of spots was carried out at 320 nm using absorbance reflectance mode. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 200 to 800 ng/spot for withanolide A and 50 to 350 ng/spot for bacoside A. The limit of detection and limit of quantification for the withanolide A were found to be 3.05 and 10.06 ng/spot, respectively and for bacoside A 8.3 and 27.39 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed formulation.

Development and validation of a HPTLC method for simultaneous estimation of lornoxicam and thiocolchicoside in combined dosage form.

PubMed

Sahoo, Madhusmita; Syal, Pratima; Hable, Asawaree A; Raut, Rahul P; Choudhari, Vishnu P; Kuchekar, Bhanudas S

2011-07-01

To develop a simple, precise, rapid and accurate HPTLC method for the simultaneous estimation of Lornoxicam (LOR) and Thiocolchicoside (THIO) in bulk and pharmaceutical dosage forms. The separation of the active compounds from pharmaceutical dosage form was carried out using methanol:chloroform:water (9.6:0.2:0.2 v/v/v) as the mobile phase and no immiscibility issues were found. The densitometric scanning was carried out at 377 nm. The method was validated for linearity, accuracy, precision, LOD (Limit of Detection), LOQ (Limit of Quantification), robustness and specificity. The Rf values (±SD) were found to be 0.84 ± 0.05 for LOR and 0.58 ± 0.05 for THIO. Linearity was obtained in the range of 60-360 ng/band for LOR and 30-180 ng/band for THIO with correlation coefficients r(2) = 0.998 and 0.999, respectively. The percentage recovery for both the analytes was in the range of 98.7-101.2 %. The proposed method was optimized and validated as per the ICH guidelines.

Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited).

PubMed

Mirnov, V V; Brower, D L; Den Hartog, D J; Ding, W X; Duff, J; Parke, E

2014-11-01

At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = Te/mec(2) model may be insufficient; we present a more precise model with τ(2)-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of Te measurement relevant to ITER operational scenarios.

Simultaneous quantification of coumarins, flavonoids and limonoids in Fructus Citri Sarcodactylis by high performance liquid chromatography coupled with diode array detector.

PubMed

Chu, Jun; Li, Song-Lin; Yin, Zhi-Qi; Ye, Wen-Cai; Zhang, Qing-Wen

2012-07-01

A high performance liquid chromatography coupled with diode array detector (HPLC-DAD) method was developed for simultaneous quantification of eleven major bioactive components including six coumarins, three flavonoids and two limonoids in Fructus Citri Sarcodactylis. The analysis was performed on a Cosmosil 5 C(18)-MS-II column (4.6 mm × 250 mm, 5 μm) with water-acetonitrile gradient elution. The method was validated in terms of linearity, sensitivity, precision, stability and accuracy. It was found that the calibration curves for all analytes showed good linearity (R(2)>0.9993) within the test ranges. The overall limit of detection (LOD) and limit of quantification (LOQ) were less than 3.0 and 10.2 ng. The relative standard deviations (RSDs) for intra- and inter-day repeatability were not more than 4.99% and 4.92%, respectively. The sample was stable for at least 48 h. The spike recoveries of eleven components were 95.1-104.9%. The established method was successfully applied to determine eleven components in three samples from different locations. The results showed that the newly developed HPLC-DAD method was linear, sensitive, precise and accurate, and could be used for quality control of Fructus Citri Sarcodactylis. Copyright © 2012 Elsevier B.V. All rights reserved.

Precision Pointing in Space Using Arrays of Shape Memory Based Linear Actuators

NASA Astrophysics Data System (ADS)

Sonawane, Nikhil

Space systems such as communication satellites, earth observation satellites and telescope require accurate pointing to observe fixed targets over prolonged time. These systems typically use reaction wheels to slew the spacecraft and gimballing systems containing motors to achieve precise pointing. Motor based actuators have limited life as they contain moving parts that require lubrication in space. Alternate methods have utilized piezoelectric actuators. This paper presents Shape memory alloys (SMA) actuators for control of a deployable antenna placed on a satellite. The SMAs are operated as a series of distributed linear actuators. These distributed linear actuators are not prone to single point failures and although each individual actuator is imprecise due to hysteresis and temperature variation, the system as a whole achieves reliable results. The SMAs can be programmed to perform a series of periodic motion and operate as a mechanical guidance system that is not prone to damage from radiation or space weather. Efforts are focused on developing a system that can achieve 1 degree pointing accuracy at first, with an ultimate goal of achieving a few arc seconds accuracy. Bench top model of the actuator system has been developed and working towards testing the system under vacuum. A demonstration flight of the technology is planned aboard a CubeSat.

Method development and validation of potent pyrimidine derivative by UV-VIS spectrophotometer.

PubMed

Chaudhary, Anshu; Singh, Anoop; Verma, Prabhakar Kumar

2014-12-01

A rapid and sensitive ultraviolet-visible (UV-VIS) spectroscopic method was developed for the estimation of pyrimidine derivative 6-Bromo-3-(6-(2,6-dichlorophenyl)-2-(morpolinomethylamino) pyrimidine4-yl) -2H-chromen-2-one (BT10M) in bulk form. Pyrimidine derivative was monitored at 275 nm with UV detection, and there is no interference of diluents at 275 nm. The method was found to be linear in the range of 50 to 150 μg/ml. The accuracy and precision were determined and validated statistically. The method was validated as a guideline. The results showed that the proposed method is suitable for the accurate, precise, and rapid determination of pyrimidine derivative. Graphical Abstract Method development and validation of potent pyrimidine derivative by UV spectroscopy.

An Online Gravity Modeling Method Applied for High Precision Free-INS

PubMed Central

Wang, Jing; Yang, Gongliu; Li, Jing; Zhou, Xiao

2016-01-01

For real-time solution of inertial navigation system (INS), the high-degree spherical harmonic gravity model (SHM) is not applicable because of its time and space complexity, in which traditional normal gravity model (NGM) has been the dominant technique for gravity compensation. In this paper, a two-dimensional second-order polynomial model is derived from SHM according to the approximate linear characteristic of regional disturbing potential. Firstly, deflections of vertical (DOVs) on dense grids are calculated with SHM in an external computer. And then, the polynomial coefficients are obtained using these DOVs. To achieve global navigation, the coefficients and applicable region of polynomial model are both updated synchronously in above computer. Compared with high-degree SHM, the polynomial model takes less storage and computational time at the expense of minor precision. Meanwhile, the model is more accurate than NGM. Finally, numerical test and INS experiment show that the proposed method outperforms traditional gravity models applied for high precision free-INS. PMID:27669261

An Online Gravity Modeling Method Applied for High Precision Free-INS.

PubMed

Wang, Jing; Yang, Gongliu; Li, Jing; Zhou, Xiao

2016-09-23

For real-time solution of inertial navigation system (INS), the high-degree spherical harmonic gravity model (SHM) is not applicable because of its time and space complexity, in which traditional normal gravity model (NGM) has been the dominant technique for gravity compensation. In this paper, a two-dimensional second-order polynomial model is derived from SHM according to the approximate linear characteristic of regional disturbing potential. Firstly, deflections of vertical (DOVs) on dense grids are calculated with SHM in an external computer. And then, the polynomial coefficients are obtained using these DOVs. To achieve global navigation, the coefficients and applicable region of polynomial model are both updated synchronously in above computer. Compared with high-degree SHM, the polynomial model takes less storage and computational time at the expense of minor precision. Meanwhile, the model is more accurate than NGM. Finally, numerical test and INS experiment show that the proposed method outperforms traditional gravity models applied for high precision free-INS.

Analytical Method Development and Validation for the Simultaneous Estimation of Abacavir and Lamivudine by Reversed-phase High-performance Liquid Chromatography in Bulk and Tablet Dosage Forms.

PubMed

Raees Ahmad, Sufiyan Ahmad; Patil, Lalit; Mohammed Usman, Mohammed Rageeb; Imran, Mohammad; Akhtar, Rashid

2018-01-01

A simple rapid, accurate, precise, and reproducible validated reverse phase high performance liquid chromatography (HPLC) method was developed for the determination of Abacavir (ABAC) and Lamivudine (LAMI) in bulk and tablet dosage forms. The quantification was carried out using Symmetry Premsil C18 (250 mm × 4.6 mm, 5 μm) column run in isocratic way using mobile phase comprising methanol: water (0.05% orthophosphoric acid with pH 3) 83:17 v/v and a detection wavelength of 245 nm and injection volume of 20 μl, with a flow rate of 1 ml/min. In the developed method, the retention times of ABAC and LAMI were found to be 3.5 min and 7.4 min, respectively. The method was validated in terms of linearity, precision, accuracy, limits of detection, limits of quantitation, and robustness in accordance with the International Conference on Harmonization guidelines. The assay of the proposed method was found to be 99% - 101%. The recovery studies were also carried out and mean % recovery was found to be 99% - 101%. The % relative standard deviation from reproducibility was found to be <2%. The proposed method was statistically evaluated and can be applied for routine quality control analysis of ABAC and LAMI in bulk and in tablet dosage form. Attempts were made to develop RP-HPLC method for simultaneous estimation of Abacavir and Lamivudine for the RP-HPLC method. The developed method was validated according to the ICH guidelines. The linearity, precision, range, robustness were within the limits as specified by the ICH guidelines. Hence the method was found to be simple, accurate, precise, economic and reproducible. So the proposed methods can be used for the routine quality control analysis of Abacavir and Lamivudine in bulk drug as well as in formulations. Abbreviations Used: HPLC: High-performance liquid chromatography, UV: Ultraviolet, ICH: International Conference on Harmonization, ABAC: Abacavir, LAMI: Lamivudine, HIV: Human immunodeficiency virus, AIDS: Acquired immunodeficiency syndrome, NRTI: Nucleoside reverse transcriptase inhibitors, ARV: Antiretroviral, RSD: Relative standard deviation, RT: Retention time, SD: Standard deviation.

Development of a non-invasive LED based device for adipose tissue thickness measurements in vivo

NASA Astrophysics Data System (ADS)

Volceka, K.; Jakovels, D.; Arina, Z.; Zaharans, J.; Kviesis, E.; Strode, A.; Svampe, E.; Ozolina-Moll, L.; Butnere, M. M.

2012-06-01

There are a number of techniques for body composition assessment in clinics and in field-surveys, but in all cases the applied methods have advantages and disadvantages. High precision imaging methods are available, though expensive and non-portable, however, the methods devised for the mass population, often suffer from the lack of precision. Therefore, the development of a safe, mobile, non-invasive, optical method that would be easy to perform, precise and low-cost, but also would offer an accurate assessment of subcutaneous adipose tissue (SAT) both in lean and in obese persons is required. Thereof, the diffuse optical spectroscopy is advantageous over the aforementioned techniques. A prototype device using an optical method for measurement of the SAT thickness in vivo has been developed. The probe contained multiple LEDs (660nm) distributed at various distances from the photo-detector which allow different light penetration depths into the subcutaneous tissue. The differences of the reflected light intensities were used to create a non-linear model, and the computed values were compared with the corresponding thicknesses of SAT, assessed by B-mode ultrasonography. The results show that with the optical system used in this study, accurate results of different SAT thicknesses can be obtained, and imply a further potential for development of multispectral optical system to observe changes of SAT thickness as well as to determine the percentage of total body fat.

Two-point T1 measurement: wide-coverage optimizations by stochastic simulations.

PubMed

Lin, M S; Fletcher, J W; Donati, R M

1986-08-01

Stochastic reliability of T1 measurement from image signal ratios is examined in the ideal case by stochastic simulations in the context of wide-coverage optimizations. Precise measurements prove to be accurate, and accurate ones precise. Sign-preserved inversion-recovery (IR)/non-IR techniques are the best ratio method, reciprocal non-IR/IR ones being equivalent, but inconvenient. Wide-coverage optima are relatively unsharp. Suggested guidelines for covering the 150- to 1500-ms T1 band are minimal relevant TE; TI about 400 ms; effective repetition times about in the ratio, TR2(IR)/TR1 (non-IR) = 2.5-3.0, and in a sum as long as possible up to about TR1 + TR2 = 3.5-4.0 s; signal-averaging after and only after TR1 + TR2 has been lengthened to the said region. Also suggested are different guidelines for covering T1 bands, 120-1200 and 200-1800 ms. Typically, precisions and accuracies improve linearly or faster with increasing S/N and (S/N)2, respectively. Unnecessarily high pixel resolutions or thin slicings exact great penalties in accuracies. Progressively shortening TR1 eventually transforms a wide coverage into a sharp targeting with small potential gains in a narrow T1 locality and large compromises almost everywhere else. The simulations yield an insight into applicabilities of standard error propagation analyses in two-point T1 measurement.

ISO/IEC 17025 Sysmex R-500 hematology reticulocyte analyzer validation.

PubMed

Dimopoulou, H A; Theodoridis, T; Galea, V; Christopoulou-Cokkinou, V; Spyridaki, M-H E; Georgakopoulos, C G

2007-01-01

The Sysmex R-500 (R-500) Hematology Analyzer is a bench-top system appropriate for the analysis of limited batches of blood samples. The R-500 provides percentage proportional (RET%), absolute reticulocyte (RET#), and absolute red blood cell (RBC#) counts. The system was validated at the Doping Control Laboratory of Athens, according to the International Committee for Standardization in Hematology, International Standards Organization (ISO/IEC) 17025, and World Antidoping Agency (WADA) specifications. The instrument calibration was performed according to the manufacturer and validation parameters comprised linearity, precision, uncertainty (intermediate and long-term precision), comparability, effect of drift, carryover, stability, and accuracy. The linearity and the comparability studies for RET#, RET%, and RBC# were expressed in regression factors (R2) and coefficients of correlation [r(x, y)], respectively. For the precision studies, the coefficients of variation for RET#, RET%, and RBC# were 9.49%, 9.83%, and <1.5%, respectively. For the intermediate precision studies, the coefficients of variation for RET#, RET%, and RBC# were 3.1%, 3.6%, and 0.6%, respectively. Carryover was found to be negligible. Sample stability was demonstrated at both room temperature and at 4 degrees C over a 24-hour period. Comparability studies for the R-500 were performed using a Sysmex SE-9500. The total evaluation led to the conclusion that the R-500 is an accurate and precise analyzer and because of to its relatively limited size, it can be considered a portable instrument, capable to be used in sports competition and training sites, where doping control and health tests are conducted. The analytical methodology of RET% measurement by the R-500 has been incorporated into the Doping Control Laboratory of Athens' Scope of Accreditation according to the ISO/IEC 17025 and WADA specifications.

Validation of a method for quantitation of the clopidogrel active metabolite, clopidogrel, clopidogrel carboxylic acid, and 2-oxo-clopidogrel in feline plasma.

PubMed

Lyngby, Janne G; Court, Michael H; Lee, Pamela M

2017-08-01

The clopidogrel active metabolite (CAM) is unstable and challenging to quantitate. The objective was to validate a new method for stabilization and quantitation of CAM, clopidogrel, and the inactive metabolites clopidogrel carboxylic acid and 2-oxo-clopiodgrel in feline plasma. Two healthy cats administered clopidogrel to demonstrate assay in vivo utility. Stabilization of CAM was achieved by adding 2-bromo-3'methoxyacetophenone to blood tubes to form a derivatized CAM (CAM-D). Method validation included evaluation of calibration curve linearity, accuracy, and precision; within and between assay precision and accuracy; and compound stability using spiked blank feline plasma. Analytes were measured by high performance liquid chromatography with tandem mass spectrometry. In vivo utility was demonstrated by a pharmacokinetic study of cats given a single oral dose of 18.75mg clopidogrel. The 2-oxo-clopidogrel metabolite was unstable. Clopidogrel, CAM-D, and clopidogrel carboxylic acid appear stable for 1 week at room temperature and 9 months at -80°C. Standard curves showed linearity for CAM-D, clopidogrel, and clopidogrel carboxylic acid (r > 0.99). Between assay accuracy and precision was ≤2.6% and ≤7.1% for CAM-D and ≤17.9% and ≤11.3% for clopidogrel and clopidogrel carboxylic acid. Within assay precision for all three compounds was ≤7%. All three compounds were detected in plasma from healthy cats receiving clopidogrel. This methodology is accurate and precise for simultaneous quantitation of CAM-D, clopidogrel, and clopidogrel carboxylic acid in feline plasma but not 2-oxo-clopidogrel. Validation of this assay is the first step to more fully understanding the use of clopidogrel in cats. Copyright © 2017 Elsevier B.V. All rights reserved.

Cutting force measurement of electrical jigsaw by strain gauges

NASA Astrophysics Data System (ADS)

Kazup, L.; Varadine Szarka, A.

2016-11-01

This paper describes a measuring method based on strain gauges for accurate specification of electric jigsaw's cutting force. The goal of the measurement is to provide an overall perspective about generated forces in a jigsaw's gearbox during a cutting period. The lifetime of the tool is affected by these forces primarily. This analysis is part of the research and development project aiming to develop a special linear magnetic brake for realizing automatic lifetime tests of electric jigsaws or similar handheld tools. The accurate specification of cutting force facilitates to define realistic test cycles during the automatic lifetime test. The accuracy and precision resulted by the well described cutting force characteristic and the possibility of automation provide new dimension for lifetime testing of the handheld tools with alternating movement.

Validation of analytical methods in GMP: the disposable Fast Read 102® device, an alternative practical approach for cell counting.

PubMed

Gunetti, Monica; Castiglia, Sara; Rustichelli, Deborah; Mareschi, Katia; Sanavio, Fiorella; Muraro, Michela; Signorino, Elena; Castello, Laura; Ferrero, Ivana; Fagioli, Franca

2012-05-31

The quality and safety of advanced therapy products must be maintained throughout their production and quality control cycle to ensure their final use in patients. We validated the cell count method according to the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use and European Pharmacopoeia, considering the tests' accuracy, precision, repeatability, linearity and range. As the cell count is a potency test, we checked accuracy, precision, and linearity, according to ICH Q2. Briefly our experimental approach was first to evaluate the accuracy of Fast Read 102® compared to the Bürker chamber. Once the accuracy of the alternative method was demonstrated, we checked the precision and linearity test only using Fast Read 102®. The data were statistically analyzed by average, standard deviation and coefficient of variation percentages inter and intra operator. All the tests performed met the established acceptance criteria of a coefficient of variation of less than ten percent. For the cell count, the precision reached by each operator had a coefficient of variation of less than ten percent (total cells) and under five percent (viable cells). The best range of dilution, to obtain a slope line value very similar to 1, was between 1:8 and 1:128. Our data demonstrated that the Fast Read 102® count method is accurate, precise and ensures the linearity of the results obtained in a range of cell dilution. Under our standard method procedures, this assay may thus be considered a good quality control method for the cell count as a batch release quality control test. Moreover, the Fast Read 102® chamber is a plastic, disposable device that allows a number of samples to be counted in the same chamber. Last but not least, it overcomes the problem of chamber washing after use and so allows a cell count in a clean environment such as that in a Cell Factory. In a good manufacturing practice setting the disposable cell counting devices will allow a single use of the count chamber they can then be thrown away, thus avoiding the waste disposal of vital dye (e.g. Trypan Blue) or lysing solution (e.g. Tuerk solution).

Validation of analytical methods in GMP: the disposable Fast Read 102® device, an alternative practical approach for cell counting

PubMed Central

2012-01-01

Background The quality and safety of advanced therapy products must be maintained throughout their production and quality control cycle to ensure their final use in patients. We validated the cell count method according to the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use and European Pharmacopoeia, considering the tests’ accuracy, precision, repeatability, linearity and range. Methods As the cell count is a potency test, we checked accuracy, precision, and linearity, according to ICH Q2. Briefly our experimental approach was first to evaluate the accuracy of Fast Read 102® compared to the Bürker chamber. Once the accuracy of the alternative method was demonstrated, we checked the precision and linearity test only using Fast Read 102®. The data were statistically analyzed by average, standard deviation and coefficient of variation percentages inter and intra operator. Results All the tests performed met the established acceptance criteria of a coefficient of variation of less than ten percent. For the cell count, the precision reached by each operator had a coefficient of variation of less than ten percent (total cells) and under five percent (viable cells). The best range of dilution, to obtain a slope line value very similar to 1, was between 1:8 and 1:128. Conclusions Our data demonstrated that the Fast Read 102® count method is accurate, precise and ensures the linearity of the results obtained in a range of cell dilution. Under our standard method procedures, this assay may thus be considered a good quality control method for the cell count as a batch release quality control test. Moreover, the Fast Read 102® chamber is a plastic, disposable device that allows a number of samples to be counted in the same chamber. Last but not least, it overcomes the problem of chamber washing after use and so allows a cell count in a clean environment such as that in a Cell Factory. In a good manufacturing practice setting the disposable cell counting devices will allow a single use of the count chamber they can then be thrown away, thus avoiding the waste disposal of vital dye (e.g. Trypan Blue) or lysing solution (e.g. Tuerk solution). PMID:22650233

Clinical Evaluation of the BD FACSPresto™ Near-Patient CD4 Counter in Kenya

PubMed Central

Angira, Francis; Akoth, Benta; Omolo, Paul; Opollo, Valarie; Bornheimer, Scott; Judge, Kevin; Tilahun, Henok; Lu, Beverly; Omana-Zapata, Imelda; Zeh, Clement

2016-01-01

Background The BD FACSPresto™ Near-Patient CD4 Counter was developed to expand HIV/AIDS management in resource-limited settings. It measures absolute CD4 counts (AbsCD4), percent CD4 (%CD4), and hemoglobin (Hb) from a single drop of capillary or venous blood in approximately 23 minutes, with throughput of 10 samples per hour. We assessed the performance of the BD FACSPresto system, evaluating accuracy, stability, linearity, precision, and reference intervals using capillary and venous blood at KEMRI/CDC HIV-research laboratory, Kisumu, Kenya, and precision and linearity at BD Biosciences, California, USA. Methods For accuracy, venous samples were tested using the BD FACSCalibur™ instrument with BD Tritest™ CD3/CD4/CD45 reagent, BD Trucount™ tubes, and BD Multiset™ software for AbsCD4 and %CD4, and the Sysmex™ KX-21N for Hb. Stability studies evaluated duration of staining (18–120-minute incubation), and effects of venous blood storage <6–24 hours post-draw. A normal cohort was tested for reference intervals. Precision covered multiple days, operators, and instruments. Linearity required mixing two pools of samples, to obtain evenly spaced concentrations for AbsCD4, total lymphocytes, and Hb. Results AbsCD4 and %CD4 venous/capillary (N = 189/ N = 162) accuracy results gave Deming regression slopes within 0.97–1.03 and R2 ≥0.96. For Hb, Deming regression results were R2 ≥0.94 and slope ≥0.94 for both venous and capillary samples. Stability varied within 10% 2 hours after staining and for venous blood stored less than 24 hours. Reference intervals results showed that gender—but not age—differences were statistically significant (p<0.05). Precision results had <3.5% coefficient of variation for AbsCD4, %CD4, and Hb, except for low AbsCD4 samples (<6.8%). Linearity was 42–4,897 cells/μL for AbsCD4, 182–11,704 cells/μL for total lymphocytes, and 2–24 g/dL for Hb. Conclusions The BD FACSPresto system provides accurate, precise clinical results for capillary or venous blood samples and is suitable for near-patient CD4 testing. Trial Registration ClinicalTrials.gov NCT02396355 PMID:27483008

Simultaneous Determination of Crypto-Chlorogenic Acid, Isoquercetin, and Astragalin Contents in Moringa oleifera Leaf Extracts by TLC-Densitometric Method

PubMed Central

Vongsak, Boonyadist; Sithisarn, Pongtip; Gritsanapan, Wandee

2013-01-01

Moringa oleifera Lamarck (Moringaceae) is used as a multipurpose medicinal plant for the treatment of various diseases. Isoquercetin, astragalin, and crypto-chlorogenic acid have been previously found to be major active components in the leaves of this plant. In this study, a thin-layer-chromatography (TLC-)densitometric method was developed and validated for simultaneous quantification of these major components in the 70% ethanolic extracts of M. oleifera leaves collected from 12 locations. The average amounts of crypto-chlorogenic acid, isoquercetin, and astragalin were found to be 0.0473, 0.0427, and 0.0534% dry weight, respectively. The method was validated for linearity, precision, accuracy, limit of detection, limit of quantitation, and robustness. The linearity was obtained in the range of 100–500 ng/spot with a correlation coefficient (r) over 0.9961. Intraday and interday precisions demonstrated relative standard deviations of less than 5%. The accuracy of the method was confirmed by determining the recovery. The average recoveries of each component from the extracts were in the range of 98.28 to 99.65%. Additionally, the leaves from Chiang Mai province contained the highest amounts of all active components. The proposed TLC-densitometric method was simple, accurate, precise, and cost-effective for routine quality controlling of M. oleifera leaf extracts. PMID:23533530

Statistical behavior of ten million experimental detection limits

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-02-01

Using a lab-constructed laser-excited fluorimeter, together with bootstrapping methodology, the authors have generated many millions of experimental linear calibration curves for the detection of rhodamine 6G tetrafluoroborate in ethanol solutions. The detection limits computed from them are in excellent agreement with both previously published theory and with comprehensive Monte Carlo computer simulations. Currie decision levels and Currie detection limits, each in the theoretical, chemical content domain, were found to be simply scaled reciprocals of the non-centrality parameter of the non-central t distribution that characterizes univariate linear calibration curves that have homoscedastic, additive Gaussian white noise. Accurate and precise estimates of the theoretical, content domain Currie detection limit for the experimental system, with 5% (each) probabilities of false positives and false negatives, are presented.

Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keck, B D; Ognibene, T; Vogel, J S

2010-02-05

Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of anymore » separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg equivalents. AMS provides an sensitive, accurate and precise method of measuring drug compounds in biological matrices.« less

A Sub-Millimetric 3-DOF Force Sensing Instrument with Integrated Fiber Bragg Grating for Retinal Microsurgery

PubMed Central

He, Xingchi; Handa, James; Gehlbach, Peter; Taylor, Russell; Iordachita, Iulian

2013-01-01

Vitreoretinal surgery requires very fine motor control to perform precise manipulation of the delicate tissue in the interior of the eye. Besides physiological hand tremor, fatigue, poor kinesthetic feedback, and patient movement, the absence of force sensing is one of the main technical challenges. Previous two degrees of freedom (DOF) force sensing instruments have demonstrated robust force measuring performance. The main design challenge is to incorporate high sensitivity axial force sensing. This paper reports the development of a sub-millimetric 3-DOF force sensing pick instrument based on fiber Bragg grating (FBG) sensors. The configuration of the four FBG sensors is arranged to maximize the decoupling between axial and transverse force sensing. A super-elastic nitinol flexure is designed to achieve high axial force sensitivity. An automated calibration system was developed for repeatability testing, calibration, and validation. Experimental results demonstrate a FBG sensor repeatability of 1.3 pm. The linear model for calculating the transverse forces provides an accurate global estimate. While the linear model for axial force is only locally accurate within a conical region with a 30° vertex angle, a second-order polynomial model can provide a useful global estimate for axial force. Combining the linear model for transverse forces and nonlinear model for axial force, the 3-DOF force sensing instrument can provide sub-millinewton resolution for axial force and a quarter millinewton for transverse forces. Validation with random samples show the force sensor can provide consistent and accurate measurement of three dimensional forces. PMID:24108455

Effect of removing the common mode errors on linear regression analysis of noise amplitudes in position time series of a regional GPS network & a case study of GPS stations in Southern California

NASA Astrophysics Data System (ADS)

Jiang, Weiping; Ma, Jun; Li, Zhao; Zhou, Xiaohui; Zhou, Boye

2018-05-01

The analysis of the correlations between the noise in different components of GPS stations has positive significance to those trying to obtain more accurate uncertainty of velocity with respect to station motion. Previous research into noise in GPS position time series focused mainly on single component evaluation, which affects the acquisition of precise station positions, the velocity field, and its uncertainty. In this study, before and after removing the common-mode error (CME), we performed one-dimensional linear regression analysis of the noise amplitude vectors in different components of 126 GPS stations with a combination of white noise, flicker noise, and random walking noise in Southern California. The results show that, on the one hand, there are above-moderate degrees of correlation between the white noise amplitude vectors in all components of the stations before and after removal of the CME, while the correlations between flicker noise amplitude vectors in horizontal and vertical components are enhanced from un-correlated to moderately correlated by removing the CME. On the other hand, the significance tests show that, all of the obtained linear regression equations, which represent a unique function of the noise amplitude in any two components, are of practical value after removing the CME. According to the noise amplitude estimates in two components and the linear regression equations, more accurate noise amplitudes can be acquired in the two components.

Bit Grooming: Statistically accurate precision-preserving quantization with compression, evaluated in the netCDF operators (NCO, v4.4.8+)

DOE PAGES

Zender, Charles S.

2016-09-19

Geoscientific models and measurements generate false precision (scientifically meaningless data bits) that wastes storage space. False precision can mislead (by implying noise is signal) and be scientifically pointless, especially for measurements. By contrast, lossy compression can be both economical (save space) and heuristic (clarify data limitations) without compromising the scientific integrity of data. Data quantization can thus be appropriate regardless of whether space limitations are a concern. We introduce, implement, and characterize a new lossy compression scheme suitable for IEEE floating-point data. Our new Bit Grooming algorithm alternately shaves (to zero) and sets (to one) the least significant bits ofmore » consecutive values to preserve a desired precision. This is a symmetric, two-sided variant of an algorithm sometimes called Bit Shaving that quantizes values solely by zeroing bits. Our variation eliminates the artificial low bias produced by always zeroing bits, and makes Bit Grooming more suitable for arrays and multi-dimensional fields whose mean statistics are important. Bit Grooming relies on standard lossless compression to achieve the actual reduction in storage space, so we tested Bit Grooming by applying the DEFLATE compression algorithm to bit-groomed and full-precision climate data stored in netCDF3, netCDF4, HDF4, and HDF5 formats. Bit Grooming reduces the storage space required by initially uncompressed and compressed climate data by 25–80 and 5–65 %, respectively, for single-precision values (the most common case for climate data) quantized to retain 1–5 decimal digits of precision. The potential reduction is greater for double-precision datasets. When used aggressively (i.e., preserving only 1–2 digits), Bit Grooming produces storage reductions comparable to other quantization techniques such as Linear Packing. Unlike Linear Packing, whose guaranteed precision rapidly degrades within the relatively narrow dynamic range of values that it can compress, Bit Grooming guarantees the specified precision throughout the full floating-point range. Data quantization by Bit Grooming is irreversible (i.e., lossy) yet transparent, meaning that no extra processing is required by data users/readers. Hence Bit Grooming can easily reduce data storage volume without sacrificing scientific precision or imposing extra burdens on users.« less

Accurate and precise determination of isotopic ratios by MC-ICP-MS: a review.

PubMed

Yang, Lu

2009-01-01

For many decades the accurate and precise determination of isotope ratios has remained a very strong interest to many researchers due to its important applications in earth, environmental, biological, archeological, and medical sciences. Traditionally, thermal ionization mass spectrometry (TIMS) has been the technique of choice for achieving the highest accuracy and precision. However, recent developments in multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) have brought a new dimension to this field. In addition to its simple and robust sample introduction, high sample throughput, and high mass resolution, the flat-topped peaks generated by this technique provide for accurate and precise determination of isotope ratios with precision reaching 0.001%, comparable to that achieved with TIMS. These features, in combination with the ability of the ICP source to ionize nearly all elements in the periodic table, have resulted in an increased use of MC-ICP-MS for such measurements in various sample matrices. To determine accurate and precise isotope ratios with MC-ICP-MS, utmost care must be exercised during sample preparation, optimization of the instrument, and mass bias corrections. Unfortunately, there are inconsistencies and errors evident in many MC-ICP-MS publications, including errors in mass bias correction models. This review examines "state-of-the-art" methodologies presented in the literature for achievement of precise and accurate determinations of isotope ratios by MC-ICP-MS. Some general rules for such accurate and precise measurements are suggested, and calculations of combined uncertainty of the data using a few common mass bias correction models are outlined.

Performance evaluation of the Aptima® HCV Quant Dx assay for hepatitis C virus (HCV) RNA detection and quantification in comparison to the Abbott RealTime HCV assay.

PubMed

Garbuglia, Anna Rosa; Bibbò, Angela; Sciamanna, Roberta; Pisciotta, Marina; Capobianchi, Maria Rosaria

2017-07-01

The Aptima HCV Quant Dx assay (Aptima) is a real-time transcription-mediated amplification assay CE-approved for the diagnosis and monitoring of hepatitis C virus (HCV) infection. Aptima's analytical performance was compared to the Abbott RealTime HCV assay (RealTime) in a clinical routine setting. Overall 295 clinical plasma samples (117 prospective/fresh; 178 retrospective/frozen) from HCV-infected patients were tested in Aptima and RealTime to determine concordance on qualitative and quantitative results. Linearity and precision at low viral loads (VLs; 0.8-3.3LogIU/mL) was tested using dilutions of the 5th WHO standard, in 10 and 20 replicates in the two assays, respectively. The ability to measure different HCV genotypes and accuracy were analyzed using the Seracare EQA panel. Inter-assay agreement for qualitative results (prospective samples) was 88% (kappa=0.78). For the 127 samples with quantitative results in both assays, Aptima yielded on average slightly higher values (by 0.24LogIU/mL; Bland-Altman method) than RealTime. Concordance between assay results was excellent (R=0.98). At low VLs (0.8-3.3LogIU/mL), Aptima demonstrated good linearity and precision, similar to RealTime. Aptima detected and accurately quantified all main HCV genotypes. Aptima demonstrated excellent precision, linearity, and accuracy in all genotypes tested. Good concordance was observed between Aptima and RealTime assays in clinical samples. The performance of the Aptima assay, on the fully automated Panther platform, makes it an excellent candidate for the detection and monitoring of HCV RNA in plasma and serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products.

PubMed

Collier, J W; Shah, R B; Bryant, A R; Habib, M J; Khan, M A; Faustino, P J

2011-02-20

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. Published by Elsevier B.V.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

PubMed Central

Collier, J.W.; Shah, R.B.; Bryant, A.R.; Habib, M.J.; Khan, M.A.; Faustino, P.J.

2011-01-01

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (l-T4) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250mm × 3.9mm) using a 0.01 M phosphate buffer (pH 3.0)–methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 µL and the column temperature was maintained at 28 °C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r2 > 0.99) over the analytical range of 0.08–0.8 µg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for l-T4 over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. PMID:20947276

Model based design of electronic throttle control

NASA Astrophysics Data System (ADS)

Cherian, Fenin; Ranjan, Ashish; Bhowmick, Pathikrit; Rammohan, A.

2017-11-01

With the advent of torque based Engine Management Systems, the precise control and robust performance of the throttle body becomes a key factor in the overall performance of the vehicle. Electronic Throttle Control provides benefits such as improved air-fuel ratio for improving the vehicle performance and lower exhausts emissions to meet the stringent emission norms. Modern vehicles facilitate various features such as Cruise Control, Traction Control, Electronic Stability Program and Pre-crash systems. These systems require control over engine power without driver intervention, which is not possible with conventional mechanical throttle system. Thus these systems are integrated to function with the electronic throttle control. However, due to inherent non-linearities in the throttle body, the control becomes a difficult task. In order to eliminate the influence of this hysteresis at the initial operation of the butterfly valve, a control to compensate the shortage must be added to the duty required for starting throttle operation when the initial operation is detected. Therefore, a lot of work is being done in this field to incorporate the various nonlinearities to achieve robust control. In our present work, the ETB was tested to verify the working of the system. Calibration of the TPS sensors was carried out in order to acquire accurate throttle opening angle. The response of the calibrated system was then plotted against a step input signal. A linear model of the ETB was prepared using Simulink and its response was compared with the experimental data to find out the initial deviation of the model from the actual system. To reduce this deviation, non-linearities from existing literature were introduced to the system and a response analysis was performed to check the deviation from the actual system. Based on this investigation, an introduction of a new nonlinearity parameter can be used in future to reduce the deviation further making the control of the ETB more precise and accurate.

Qualitative and Quantitative Analysis of the Major Constituents in Chinese Medical Preparation Lianhua-Qingwen Capsule by UPLC-DAD-QTOF-MS

PubMed Central

Jia, Weina; Wang, Chunhua; Wang, Yuefei; Pan, Guixiang; Jiang, Miaomiao; Li, Zheng; Zhu, Yan

2015-01-01

Lianhua-Qingwen capsule (LQC) is a commonly used Chinese medical preparation to treat viral influenza and especially played a very important role in the fight against severe acute respiratory syndrome (SARS) in 2002-2003 in China. In this paper, a rapid ultraperformance liquid chromatography coupled with diode-array detector and quadrupole time-of-flight mass spectrometry (UPLC-DAD-QTOF-MS) method was established for qualitative and quantitative analysis of the major constituents of LQC. A total of 61 compounds including flavonoids, phenylpropanoids, anthraquinones, triterpenoids, iridoids, and other types of compounds were unambiguously or tentatively identified by comparing the retention times and accurate mass measurement with reference compounds or literature data. Among them, twelve representative compounds were further quantified as chemical markers in quantitative analysis, including salidroside, chlorogenic acid, forsythoside E, cryptochlorogenic acid, amygdalin, sweroside, hyperin, rutin, forsythoside A, phillyrin, rhein, and glycyrrhizic acid. The UPLC-DAD method was evaluated with linearity, limit of detection (LOD), limit of quantification (LOQ), precision, stability, repeatability, and recovery tests. The results showed that the developed quantitative method was linear, sensitive, and precise for the quality control of LQC. PMID:25654135

Development and validation of a HPTLC method for simultaneous estimation of lornoxicam and thiocolchicoside in combined dosage form

PubMed Central

Sahoo, Madhusmita; Syal, Pratima; Hable, Asawaree A.; Raut, Rahul P.; Choudhari, Vishnu P.; Kuchekar, Bhanudas S.

2011-01-01

Aim: To develop a simple, precise, rapid and accurate HPTLC method for the simultaneous estimation of Lornoxicam (LOR) and Thiocolchicoside (THIO) in bulk and pharmaceutical dosage forms. Materials and Methods: The separation of the active compounds from pharmaceutical dosage form was carried out using methanol:chloroform:water (9.6:0.2:0.2 v/v/v) as the mobile phase and no immiscibility issues were found. The densitometric scanning was carried out at 377 nm. The method was validated for linearity, accuracy, precision, LOD (Limit of Detection), LOQ (Limit of Quantification), robustness and specificity. Results: The Rf values (±SD) were found to be 0.84 ± 0.05 for LOR and 0.58 ± 0.05 for THIO. Linearity was obtained in the range of 60–360 ng/band for LOR and 30–180 ng/band for THIO with correlation coefficients r2 = 0.998 and 0.999, respectively. The percentage recovery for both the analytes was in the range of 98.7–101.2 %. Conclusion: The proposed method was optimized and validated as per the ICH guidelines. PMID:23781452

Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mirnov, V. V.; Hartog, D. J. Den; Duff, J.

2014-11-15

At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = T{sub e}/m{sub e}c{sup 2} model may be insufficient; we present a more precise model with τ{sup 2}-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused bymore » equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of T{sub e} measurement relevant to ITER operational scenarios.« less

Lightweight diaphragm mirror module system for solar collectors

DOEpatents

Butler, Barry L.

1985-01-01

A mirror module system is provided for accurately focusing solar radiation on a point or a line as defined by an array of solar collectors. Each mirror module includes a flexible membrane stretched over a frame in a manner similar to that of a drum or a trampoline and further includes a silvered glass or plastic mirror for forming an optical reflecting surface. The configuration of the optical reflecting surface is variably adjustable to provide for the accurate focusing of the solar energy on a given collector array, e.g., a point or a linear array arrangement. The flexible mirror-membrane combination is lightweight to facilitate installation and reduce system cost yet structurally strong enough to provide for the precise focusing of the incident solar radiation in a semi-rigid reflector system in which unwanted reflector displacement is minimized.

Lightweight diaphragm mirror module system for solar collectors

DOEpatents

Butler, B.L.

1984-01-01

A mirror module system is provided for accurately focusing solar radiation on a point or a line as defined by an array of solar collectors. Each mirror module includes a flexible membrane stretched over a frame in a manner similar to that of a drum or a trampoline and further includes a silvered glass or plastic mirror for forming an optical reflecting surface. The configuration of the optical reflecting surface is variably adjustable to provide for the accurate focusing of the solar energy on a given collector array, e.g., a point or a linear array arrangement. The flexible mirror-membrane combination is lightweight to facilitate installation and reduce system cost yet structurally strong enough to provide for the precise focusing of the incident solar radiation in a semi-rigid reflector system in which unwanted reflector displacement is minimized.

The Fermi-Pasta-Ulam Problem and Its Underlying Integrable Dynamics: An Approach Through Lyapunov Exponents

NASA Astrophysics Data System (ADS)

Benettin, G.; Pasquali, S.; Ponno, A.

2018-05-01

FPU models, in dimension one, are perturbations either of the linear model or of the Toda model; perturbations of the linear model include the usual β -model, perturbations of Toda include the usual α +β model. In this paper we explore and compare two families, or hierarchies, of FPU models, closer and closer to either the linear or the Toda model, by computing numerically, for each model, the maximal Lyapunov exponent χ . More precisely, we consider statistically typical trajectories and study the asymptotics of χ for large N (the number of particles) and small ɛ (the specific energy E / N), and find, for all models, asymptotic power laws χ ˜eq Cɛ ^a, C and a depending on the model. The asymptotics turns out to be, in general, rather slow, and producing accurate results requires a great computational effort. We also revisit and extend the analytic computation of χ introduced by Casetti, Livi and Pettini, originally formulated for the β -model. With great evidence the theory extends successfully to all models of the linear hierarchy, but not to models close to Toda.

Precision measurements and computations of transition energies in rotationally cold triatomic hydrogen ions up to the midvisible spectral range.

PubMed

Pavanello, Michele; Adamowicz, Ludwik; Alijah, Alexander; Zobov, Nikolai F; Mizus, Irina I; Polyansky, Oleg L; Tennyson, Jonathan; Szidarovszky, Tamás; Császár, Attila G; Berg, Max; Petrignani, Annemieke; Wolf, Andreas

2012-01-13

First-principles computations and experimental measurements of transition energies are carried out for vibrational overtone lines of the triatomic hydrogen ion H(3)(+) corresponding to floppy vibrations high above the barrier to linearity. Action spectroscopy is improved to detect extremely weak visible-light spectral lines on cold trapped H(3)(+) ions. A highly accurate potential surface is obtained from variational calculations using explicitly correlated Gaussian wave function expansions. After nonadiabatic corrections, the floppy H(3)(+) vibrational spectrum is reproduced at the 0.1 cm(-1) level up to 16600 cm(-1).

Precision measurement of the local bias of dark matter halos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazeyras, Titouan; Wagner, Christian; Schmidt, Fabian

2016-02-01

We present accurate measurements of the linear, quadratic, and cubic local bias of dark matter halos, using curved 'separate universe' N-body simulations which effectively incorporate an infinite-wavelength overdensity. This can be seen as an exact implementation of the peak-background split argument. We compare the results with the linear and quadratic bias measured from the halo-matter power spectrum and bispectrum, and find good agreement. On the other hand, the standard peak-background split applied to the Sheth and Tormen (1999) and Tinker et al. (2008) halo mass functions matches the measured linear bias parameter only at the level of 10%. The predictionmore » from the excursion set-peaks approach performs much better, which can be attributed to the stochastic moving barrier employed in the excursion set-peaks prediction. We also provide convenient fitting formulas for the nonlinear bias parameters b{sub 2}(b{sub 1}) and b{sub 3}(b{sub 1}), which work well over a range of redshifts.« less

Development and analytical performance evaluation of FREND-SAA and FREND-Hp

NASA Astrophysics Data System (ADS)

Choi, Eunha; Seong, Jihyun; Lee, Seiyoung; Han, Sunmi

2017-07-01

The FREND System is a portable cartridge reader, quantifying analytes by measuring laser-induced fluorescence in a single-use reagent cartridge. The objective of this study was to evaluate FREND-SAA and FREND-Hp assays. The FREND-SAA and Hp assays were standardized to the WHO and IFCC reference materials. Analytical performance studies of Precision, Linearity, Limits of Detections, Interferences, and Method Comparisons for both assays were performed according to the CLSI guidelines. Both assays demonstrated acceptable imprecision of %CV in three different levels of samples. The linearity of the assays was found to be acceptable (SAA 5 150 mg/L, Hp 30 400 mg/dL). The detection limits were 3.8 mg/L (SAA) and 10.2 mg/dL (Hp). No significant interference and no significant deviation from linearity was found in the both comparison studies. In conclusion, NanoEnTek's FREND-SAA and Hp assays represent rapid, accurate and convenient means to quantify SAA and Hp in human serum on FREND system.

Sedimentation of knotted polymers

NASA Astrophysics Data System (ADS)

Piili, J.; Marenduzzo, D.; Kaski, K.; Linna, R. P.

2013-01-01

We investigate the sedimentation of knotted polymers by means of stochastic rotation dynamics, a molecular dynamics algorithm that takes hydrodynamics fully into account. We show that the sedimentation coefficient s, related to the terminal velocity of the knotted polymers, increases linearly with the average crossing number nc of the corresponding ideal knot. This provides direct computational confirmation of this relation, postulated on the basis of sedimentation experiments by Rybenkov [J. Mol. Biol.10.1006/jmbi.1996.0876 267, 299 (1997)]. Such a relation was previously shown to hold with simulations for knot electrophoresis. We also show that there is an accurate linear dependence of s on the inverse of the radius of gyration Rg-1, more specifically with the inverse of the Rg component that is perpendicular to the direction along which the polymer sediments. When the polymer sediments in a slab, the walls affect the results appreciably. However, Rg-1 remains to a good precision linearly dependent on nc. Therefore, Rg-1 is a good measure of a knot's complexity.

Optical Measurement of Radiocarbon below Unity Fraction Modern by Linear Absorption Spectroscopy.

PubMed

Fleisher, Adam J; Long, David A; Liu, Qingnan; Gameson, Lyn; Hodges, Joseph T

2017-09-21

High-precision measurements of radiocarbon ( 14 C) near or below a fraction modern 14 C of 1 (F 14 C ≤ 1) are challenging and costly. An accurate, ultrasensitive linear absorption approach to detecting 14 C would provide a simple and robust benchtop alternative to off-site accelerator mass spectrometry facilities. Here we report the quantitative measurement of 14 C in gas-phase samples of CO 2 with F 14 C < 1 using cavity ring-down spectroscopy in the linear absorption regime. Repeated analysis of CO 2 derived from the combustion of either biogenic or petrogenic sources revealed a robust ability to differentiate samples with F 14 C < 1. With a combined uncertainty of 14 C/ 12 C = 130 fmol/mol (F 14 C = 0.11), initial performance of the calibration-free instrument is sufficient to investigate a variety of applications in radiocarbon measurement science including the study of biofuels and bioplastics, illicitly traded specimens, bomb dating, and atmospheric transport.

Development and evaluation of multi-energy PbO dosimeter for quality assurance of image-guide radiation therapy devices

NASA Astrophysics Data System (ADS)

Kim, Kyo-Tae; Heo, Ye-Ji; Han, Moo-Jae; Oh, Kyung-Min; Lee, Young-Kyu; Kim, Shin-Wook; Park, Sung-Kwang

2017-04-01

In radiation therapy, accurate radiotherapy treatment plan (RTP) reproduction is necessary to optimize the clinical results. Thus, attempts have recently been made to ensure high RTP reproducibility using image-guide radiation therapy (IGRT) technology. However, the clinical use of digital X-ray equipment requires extended quality assurance (QA) for those devices, since the IGRT device quality determines the precision of intensity-modulated radiation therapy. The study described in this paper was focused on developing a multi-energy PbO dosimeter for IGRT device QA. The Schottky-type polycrystalline PbO dosimeter with a Au/PbO/ITO structure was evaluated by comparing its response coincidence, dose linearity, measurement reproducibility, linear attenuation coefficient, and percent depth dose with those of Si diode and standard ionization chamber dosimeters.

A complete study of the precision of the concentric MacLaurin spheroid method to calculate Jupiter's gravitational moments

NASA Astrophysics Data System (ADS)

Debras, F.; Chabrier, G.

2018-01-01

A few years ago, Hubbard (2012, ApJ, 756, L15; 2013, ApJ, 768, 43) presented an elegant, non-perturbative method, called concentric MacLaurin spheroid (CMS), to calculate with very high accuracy the gravitational moments of a rotating fluid body following a barotropic pressure-density relationship. Having such an accurate method is of great importance for taking full advantage of the Juno mission, and its extremely precise determination of Jupiter gravitational moments, to better constrain the internal structure of the planet. Recently, several authors have applied this method to the Juno mission with 512 spheroids linearly spaced in altitude. We demonstrate in this paper that such calculations lead to errors larger than Juno's error bars, invalidating the aforederived Jupiter models at the level required by Juno's precision. We show that, in order to fulfill Juno's observational constraints, at least 1500 spheroids must be used with a cubic, square or exponential repartition, the most reliable solutions. When using a realistic equation of state instead of a polytrope, we highlight the necessity to properly describe the outermost layers to derive an accurate boundary condition, excluding in particular a zero pressure outer condition. Providing all these constraints are fulfilled, the CMS method can indeed be used to derive Jupiter models within Juno's present observational constraints. However, we show that the treatment of the outermost layers leads to irreducible errors in the calculation of the gravitational moments and thus on the inferred physical quantities for the planet. We have quantified these errors and evaluated the maximum precision that can be reached with the CMS method in the present and future exploitation of Juno's data.

Analytical performances of the Diazyme ADA assay on the Cobas® 6000 system.

PubMed

Delacour, Hervé; Sauvanet, Christophe; Ceppa, Franck; Burnat, Pascal

2010-12-01

To evaluate the analytical performance of the Diazyme ADA assay on the Cobas® 6000 system for pleural fluid samples analysis. Imprecision, linearity, calibration curve stability, interference, and correlation studies were completed. The Diazyme ADA assay demonstrated excellent precision (CV<4%) over the analytical measurement range (0.5-117 U/L). Bilirubin above 50 μmol/L and haemoglobin above 177 μmol/L interfered with the test, inducing a negative and a positive interference respectively. The Diazyme ADA assay correlated well with the Giusti method (r(2)=0.93) but exhibited a negative bias (~ -30%). The Diazyme ADA assay on the Cobas® 6000 system represents a rapid, accurate, precise and reliable method for determination of ADA activity in pleural fluid samples. Copyright © 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Development and validation of new spectrophotometric ratio H-point standard addition method and application to gastrointestinal acting drugs mixtures.

PubMed

Yehia, Ali M

2013-05-15

New, simple, specific, accurate and precise spectrophotometric technique utilizing ratio spectra is developed for simultaneous determination of two different binary mixtures. The developed ratio H-point standard addition method (RHPSAM) was managed successfully to resolve the spectral overlap in itopride hydrochloride (ITO) and pantoprazole sodium (PAN) binary mixture, as well as, mosapride citrate (MOS) and PAN binary mixture. The theoretical background and advantages of the newly proposed method are presented. The calibration curves are linear over the concentration range of 5-60 μg/mL, 5-40 μg/mL and 4-24 μg/mL for ITO, MOS and PAN, respectively. Specificity of the method was investigated and relative standard deviations were less than 1.5. The accuracy, precision and repeatability were also investigated for the proposed method according to ICH guidelines. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and validation of new spectrophotometric ratio H-point standard addition method and application to gastrointestinal acting drugs mixtures

NASA Astrophysics Data System (ADS)

Yehia, Ali M.

2013-05-01

New, simple, specific, accurate and precise spectrophotometric technique utilizing ratio spectra is developed for simultaneous determination of two different binary mixtures. The developed ratio H-point standard addition method (RHPSAM) was managed successfully to resolve the spectral overlap in itopride hydrochloride (ITO) and pantoprazole sodium (PAN) binary mixture, as well as, mosapride citrate (MOS) and PAN binary mixture. The theoretical background and advantages of the newly proposed method are presented. The calibration curves are linear over the concentration range of 5-60 μg/mL, 5-40 μg/mL and 4-24 μg/mL for ITO, MOS and PAN, respectively. Specificity of the method was investigated and relative standard deviations were less than 1.5. The accuracy, precision and repeatability were also investigated for the proposed method according to ICH guidelines.

Novel spectrophotometric determination of flumethasone pivalate and clioquinol in their binary mixture and pharmaceutical formulation.

PubMed

Abdel-Aleem, Eglal A; Hegazy, Maha A; Sayed, Nour W; Abdelkawy, M; Abdelfatah, Rehab M

2015-02-05

This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 μg/mL for FP, and 2-25 μg/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Copyright © 2014 Elsevier B.V. All rights reserved.

Three different spectrophotometric methods manipulating ratio spectra for determination of binary mixture of Amlodipine and Atorvastatin

NASA Astrophysics Data System (ADS)

Darwish, Hany W.; Hassan, Said A.; Salem, Maissa Y.; El-Zeiny, Badr A.

2011-12-01

Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for the simultaneous determination of Amlodipine besylate (AM) and Atorvastatin calcium (AT) in tablet dosage forms. The first method is first derivative of the ratio spectra ( 1DD), the second is ratio subtraction and the third is the method of mean centering of ratio spectra. The calibration curve is linear over the concentration range of 3-40 and 8-32 μg/ml for AM and AT, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Standard deviation is <1.5 in the assay of raw materials and tablets. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit.

Three different methods for determination of binary mixture of Amlodipine and Atorvastatin using dual wavelength spectrophotometry

NASA Astrophysics Data System (ADS)

Darwish, Hany W.; Hassan, Said A.; Salem, Maissa Y.; El-Zeany, Badr A.

2013-03-01

Three simple, specific, accurate and precise spectrophotometric methods depending on the proper selection of two wavelengths are developed for the simultaneous determination of Amlodipine besylate (AML) and Atorvastatin calcium (ATV) in tablet dosage forms. The first method is the new Ratio Difference method, the second method is the Bivariate method and the third one is the Absorbance Ratio method. The calibration curve is linear over the concentration range of 4-40 and 8-32 μg/mL for AML and ATV, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Methods are validated according to the ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit. The mathematical explanation of the procedures is illustrated.

Therapeutic Drug Monitoring of Phenytoin by Simple, Rapid, Accurate, Highly Sensitive and Novel Method and Its Clinical Applications.

PubMed

Shaikh, Abdul S; Guo, Ruichen

2017-01-01

Phenytoin has very challenging pharmacokinetic properties. To prevent its toxicity and ensure efficacy, continuous therapeutic monitoring is required. It is hard to get a simple, accurate, rapid, easily available, economical and highly sensitive assay in one method for therapeutic monitoring of phenytoin. The present study is directed towards establishing and validating a simpler, rapid, an accurate, highly sensitive, novel and environment friendly liquid chromatography/mass spectrometry (LC/MS) method for offering rapid and reliable TDM results of phenytoin in epileptic patients to physicians and clinicians for making immediate and rational decision. 27 epileptics patients with uncontrolled seizures or suspected of non-compliance or toxicity of phenytoin were selected and advised for TDM of phenytoin by neurologists of Qilu Hospital Jinan, China. The LC/MS assay was used for performing of therapeutic monitoring of phenytoin. The Agilent 1100 LC/MS system was used for TDM. The mixture of Ammonium acetate 5mM: Methanol at (35: 65 v/v) was used for the composition of mobile phase. The Diamonsil C18 (150mm×4.6mm, 5μm) column was used for the extraction of analytes in plasma. The samples were prepared with one step simple protein precipitation method. The technique was validated with the guidelines of International Conference on Harmonisation (ICH). The calibration curve demonstrated decent linearity within (0.2-20 µg/mL) concentration range with linearity equation, y= 0.0667855 x +0.00241785 and correlation coefficient (R2) of 0.99928. The specificity, recovery, linearity, accuracy, precision and stability results were within the accepted limits. The concentration of 0.2 µg/mL was observed as lower limit of quantitation (LLOQ), which is 12.5 times lower than the currently available enzyme-multiplied immunoassay technique (EMIT) for measurement of phenytoin in epilepsy patients. A rapid, simple, economical, precise, highly sensitive and novel LC/MS assay has been established, validated and applied successfully in TDM of 27 epileptics patients. It was alarmingly found that TDM results of all these patients were out of safe range except two patients. However, it needs further evaluation. Besides TDM, the stated method can also be applied in bioequivalence, pharmacokinetics, toxicokinetics and pharmacovigilance studies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

A precise and accurate acupoint location obtained on the face using consistency matrix pointwise fusion method.

PubMed

Yanq, Xuming; Ye, Yijun; Xia, Yong; Wei, Xuanzhong; Wang, Zheyu; Ni, Hongmei; Zhu, Ying; Xu, Lingyu

2015-02-01

To develop a more precise and accurate method, and identified a procedure to measure whether an acupoint had been correctly located. On the face, we used an acupoint location from different acupuncture experts and obtained the most precise and accurate values of acupoint location based on the consistency information fusion algorithm, through a virtual simulation of the facial orientation coordinate system. Because of inconsistencies in each acupuncture expert's original data, the system error the general weight calculation. First, we corrected each expert of acupoint location system error itself, to obtain a rational quantification for each expert of acupuncture and moxibustion acupoint location consistent support degree, to obtain pointwise variable precision fusion results, to put every expert's acupuncture acupoint location fusion error enhanced to pointwise variable precision. Then, we more effectively used the measured characteristics of different acupuncture expert's acupoint location, to improve the measurement information utilization efficiency and acupuncture acupoint location precision and accuracy. Based on using the consistency matrix pointwise fusion method on the acupuncture experts' acupoint location values, each expert's acupoint location information could be calculated, and the most precise and accurate values of each expert's acupoint location could be obtained.

Precision manometer gauge

DOEpatents

McPherson, Malcolm J.; Bellman, Robert A.

1984-01-01

A precision manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a positioning plate which is moved vertically with machine tool precision. Double scales are provided to read the height of the positioning plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference position.

Precision manometer gauge

DOEpatents

McPherson, M.J.; Bellman, R.A.

1982-09-27

A precision manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a positioning plate which is moved vertically with machine tool precision. Double scales are provided to read the height of the positioning plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference position.

Accuracy of active chirp linearization for broadband frequency modulated continuous wave ladar.

PubMed

Barber, Zeb W; Babbitt, Wm Randall; Kaylor, Brant; Reibel, Randy R; Roos, Peter A

2010-01-10

As the bandwidth and linearity of frequency modulated continuous wave chirp ladar increase, the resulting range resolution, precisions, and accuracy are improved correspondingly. An analysis of a very broadband (several THz) and linear (<1 ppm) chirped ladar system based on active chirp linearization is presented. Residual chirp nonlinearity and material dispersion are analyzed as to their effect on the dynamic range, precision, and accuracy of the system. Measurement precision and accuracy approaching the part per billion level is predicted.

Discovery of the linear region of Near Infrared Diffuse Reflectance spectra using the Kubelka-Munk theory

NASA Astrophysics Data System (ADS)

Dai, Shengyun; Pan, Xiaoning; Ma, Lijuan; Huang, Xingguo; Du, Chenzhao; Qiao, Yanjiang; Wu, Zhisheng

2018-05-01

Particle size is of great importance for the quantitative model of the NIR diffuse reflectance. In this paper, the effect of sample particle size on the measurement of harpagoside in Radix Scrophulariae powder by near infrared diffuse (NIR) reflectance spectroscopy was explored. High-performance liquid chromatography (HPLC) was employed as a reference method to construct the quantitative particle size model. Several spectral preprocessing methods were compared, and particle size models obtained by different preprocessing methods for establishing the partial least-squares (PLS) models of harpagoside. Data showed that the particle size distribution of 125-150 μm for Radix Scrophulariae exhibited the best prediction ability with R2pre=0.9513, RMSEP=0.1029 mg·g-1, and RPD = 4.78. For the hybrid granularity calibration model, the particle size distribution of 90-180 μm exhibited the best prediction ability with R2pre=0.8919, RMSEP=0.1632 mg·g-1, and RPD = 3.09. Furthermore, the Kubelka-Munk theory was used to relate the absorption coefficient k (concentration-dependent) and scatter coefficient s (particle size-dependent). The scatter coefficient s was calculated based on the Kubelka-Munk theory to study the changes of s after being mathematically preprocessed. A linear relationship was observed between k/s and absorption A within a certain range and the value for k/s was greater than 4. According to this relationship, the model was more accurately constructed with the particle size distribution of 90-180 μm when s was kept constant or in a small linear region. This region provided a good reference for the linear modeling of diffuse reflectance spectroscopy. To establish a diffuse reflectance NIR model, further accurate assessment should be obtained in advance for a precise linear model.

NCLscan: accurate identification of non-co-linear transcripts (fusion, trans-splicing and circular RNA) with a good balance between sensitivity and precision.

PubMed

Chuang, Trees-Juen; Wu, Chan-Shuo; Chen, Chia-Ying; Hung, Li-Yuan; Chiang, Tai-Wei; Yang, Min-Yu

2016-02-18

Analysis of RNA-seq data often detects numerous 'non-co-linear' (NCL) transcripts, which comprised sequence segments that are topologically inconsistent with their corresponding DNA sequences in the reference genome. However, detection of NCL transcripts involves two major challenges: removal of false positives arising from alignment artifacts and discrimination between different types of NCL transcripts (trans-spliced, circular or fusion transcripts). Here, we developed a new NCL-transcript-detecting method ('NCLscan'), which utilized a stepwise alignment strategy to almost completely eliminate false calls (>98% precision) without sacrificing true positives, enabling NCLscan outperform 18 other publicly-available tools (including fusion- and circular-RNA-detecting tools) in terms of sensitivity and precision, regardless of the generation strategy of simulated dataset, type of intragenic or intergenic NCL event, read depth of coverage, read length or expression level of NCL transcript. With the high accuracy, NCLscan was applied to distinguishing between trans-spliced, circular and fusion transcripts on the basis of poly(A)- and nonpoly(A)-selected RNA-seq data. We showed that circular RNAs were expressed more ubiquitously, more abundantly and less cell type-specifically than trans-spliced and fusion transcripts. Our study thus describes a robust pipeline for the discovery of NCL transcripts, and sheds light on the fundamental biology of these non-canonical RNA events in human transcriptome. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

A rapid method for the simultaneous determination of 25 anti-hypertensive compounds in dietary supplements using ultra-high-pressure liquid chromatography.

PubMed

Heo, Seok; Yoo, Geum Joo; Choi, Ji Yeon; Park, Hyoung Joon; Park, Sung-Kwan; Baek, Sun Young

2016-11-01

A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20-1.00 and 0.60-3.00 μg ml -1 , respectively, while those of liquid samples were 0.30-1.20 and 0.90-3.60 μg ml -1 , respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15-6.48% and 0.28-8.67%, respectively. The intra- and inter-day accuracies were 82.25-111.42% and 80.70-115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market.

Square Wave Voltammetric Determination of Diclofenac in Pharmaceutical Preparations and Human Serum

PubMed Central

Ciltas, Ulvihan; Yilmaz, Bilal; Kaban, Selcuk; Akcay, Bilge Kaan; Nazik, Gulsah

2015-01-01

In this study, a simple and reliable square wave voltammetric (SWV) method was developed and validated for determination of diclofenac in pharmaceutical preparations and human serum. The proposed method was based on electrooxidation of diclofenac at platinum electrode in 0.1 M TBAClO4/acetonitrile solution. The well-defined two oxidation peaks were observed at 0.87 and 1.27 V, respectively. Calibration curves that were obtained by using current values measured for second peak were linear over the concentration range of 1.5-17.5 μg mL-1 and 2-20 μg mL-1 in supporting electrolyte and serum, respectively. Precision and accuracy were also checked in all media. Intra- and inter-day precision values for diclofenac were less than 3.64, and accuracy (relative error) was better than 2.49%. Developed method in this study is accurate, precise and can be easily applied to Diclomec, Dicloflam and Voltaren tablets as pharmaceutical preparation. Also, the proposed technique was successfully applied to spiked human serum samples. No electroactive interferences from the endogenous substances were found in human serum. PMID:26330859

Square Wave Voltammetric Determination of Diclofenac in Pharmaceutical Preparations and Human Serum.

PubMed

Ciltas, Ulvihan; Yilmaz, Bilal; Kaban, Selcuk; Akcay, Bilge Kaan; Nazik, Gulsah

2015-01-01

In this study, a simple and reliable square wave voltammetric (SWV) method was developed and validated for determination of diclofenac in pharmaceutical preparations and human serum. The proposed method was based on electrooxidation of diclofenac at platinum electrode in 0.1 M TBAClO4/acetonitrile solution. The well-defined two oxidation peaks were observed at 0.87 and 1.27 V, respectively. Calibration curves that were obtained by using current values measured for second peak were linear over the concentration range of 1.5-17.5 μg mL(-1) and 2-20 μg mL(-1) in supporting electrolyte and serum, respectively. Precision and accuracy were also checked in all media. Intra- and inter-day precision values for diclofenac were less than 3.64, and accuracy (relative error) was better than 2.49%. Developed method in this study is accurate, precise and can be easily applied to Diclomec, Dicloflam and Voltaren tablets as pharmaceutical preparation. Also, the proposed technique was successfully applied to spiked human serum samples. No electroactive interferences from the endogenous substances were found in human serum.

High precision optical spectroscopy and quantum state selected photodissociation of ultracold 88Sr2 molecules in an optical lattice

NASA Astrophysics Data System (ADS)

McDonald, Mickey

2017-04-01

Over the past several decades, rapid progress has been made toward the accurate characterization and control of atoms, epitomized by the ever-increasing accuracy and precision of optical atomic lattice clocks. Extending this progress to molecules will have exciting implications for chemistry, condensed matter physics, and precision tests of physics beyond the Standard Model. My thesis describes work performed over the past six years to establish the state of the art in manipulation and quantum control of ultracold molecules. We describe a thorough set of measurements characterizing the rovibrational structure of weakly bound 88Sr2 molecules from several different perspectives, including determinations of binding energies; linear, quadratic, and higher order Zeeman shifts; transition strengths between bound states; and lifetimes of narrow subradiant states. Finally, we discuss measurements of photofragment angular distributions produced by photodissociation of molecules in single quantum states, leading to an exploration of quantum-state-resolved ultracold chemistry. The images of exploding photofragments produced in these studies exhibit dramatic interference effects and strongly violate semiclassical predictions, instead requiring a fully quantum mechanical description.

Novel spectrophotometric methods for simultaneous determination of timolol and dorzolamide in their binary mixture.

PubMed

Lotfy, Hayam Mahmoud; Hegazy, Maha A; Rezk, Mamdouh R; Omran, Yasmin Rostom

2014-05-21

Two smart and novel spectrophotometric methods namely; absorbance subtraction (AS) and amplitude modulation (AM) were developed and validated for the determination of a binary mixture of timolol maleate (TIM) and dorzolamide hydrochloride (DOR) in presence of benzalkonium chloride without prior separation, using unified regression equation. Additionally, simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of the binary mixture namely; simultaneous ratio subtraction (SRS), ratio difference (RD), ratio subtraction (RS) coupled with extended ratio subtraction (EXRS), constant multiplication method (CM) and mean centering of ratio spectra (MCR). The proposed spectrophotometric procedures do not require any separation steps. Accuracy, precision and linearity ranges of the proposed methods were determined and the specificity was assessed by analyzing synthetic mixtures of both drugs. They were applied to their pharmaceutical formulation and the results obtained were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there is no significant difference between the proposed methods and the reported one regarding both accuracy and precision. Copyright © 2014 Elsevier B.V. All rights reserved.

A T-Type Capacitive Sensor Capable of Measuring 5-DOF Error Motions of Precision Spindles

PubMed Central

Xiang, Kui; Qiu, Rongbo; Mei, Deqing; Chen, Zichen

2017-01-01

The precision spindle is a core component of high-precision machine tools, and the accurate measurement of its error motions is important for improving its rotation accuracy as well as the work performance of the machine. This paper presents a T-type capacitive sensor (T-type CS) with an integrated structure. The proposed sensor can measure the 5-degree-of-freedom (5-DOF) error motions of a spindle in-situ and simultaneously by integrating electrode groups in the cylindrical bore of the stator and the outer end face of its flange, respectively. Simulation analysis and experimental results show that the sensing electrode groups with differential measurement configuration have near-linear output for the different types of rotor displacements. What’s more, the additional capacitance generated by fringe effects has been reduced about 90% with the sensing electrode groups fabricated based on flexible printed circuit board (FPCB) and related processing technologies. The improved signal processing circuit has also been increased one times in the measuring performance and makes the measured differential output capacitance up to 93% of the theoretical values. PMID:28846631

A comparative study of smart spectrophotometric methods for simultaneous determination of a skeletal muscle relaxant and an analgesic in combined dosage form

NASA Astrophysics Data System (ADS)

Salem, Hesham; Mohamed, Dalia

2015-04-01

Six simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the analgesic drug; paracetamol (PARA) and the skeletal muscle relaxant; dantrolene sodium (DANT). Three methods are manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and mean centering (MC). The other three methods are utilizing the isoabsorptive point either at zero order namely; absorbance ratio (AR) and absorbance subtraction (AS) or at ratio spectrum namely; amplitude modulation (AM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and capsules. The obtained results were statistically compared with each other and with those of reported spectrophotometric ones. The comparison showed that there is no significant difference between the proposed methods and the reported methods regarding both accuracy and precision.

Development of an isocratic HPLC method for catechin quantification and its application to formulation studies.

PubMed

Li, Danhui; Martini, Nataly; Wu, Zimei; Wen, Jingyuan

2012-10-01

The aim of this study was to develop a simple, rapid and accurate isocratic HPLC analytical method to qualify and quantify five catechin derivatives, namely (+)-catechin (C), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epicatechin (EC) and (-)-epigallocatechin gallate (EGCG). To validate the analytical method, linearity, repeatability, intermediate precision, sensitivity, selectivity and recovery were investigated. The five catechin derivatives were completely separated by HPLC using a mobile phase containing 0.1% TFA in Milli-Q water (pH 2.0) mixed with methanol at the volume ratio of 75:25 at a flow rate of 0.8 ml/min. The method was shown to be linear (r²>0.99), repeatable with instrumental precision<2.0 and intra-assay precision<2.5 (%CV, percent coefficient of variation), precise with intra-day variation<1 and inter-day variation<2.5 (%CV, percent coefficient of variation) and sensitive (LOD<1 μg/mL and LOQ<3 μg/mL) over the calibration range for all five derivatives. Derivatives could be fully recovered in the presence of niosomal formulation (recovery rates>91%). Selectivity of the method was proven by the forced degradation studies, which showed that under acidic, basic, oxidation temperature and photolysis stresses, the parent drug can be separated from the degradation products by means of this analytical method. The described method was successfully applied in the in vitro release studies of catechin-loaded niosomes to manifest its utility in formulation characterization. Obtained results indicated that the drug release from niosomal formulations was a biphasic process and a diffusion mechanism regulated the permeation of catechin niosomes. Copyright © 2012 Elsevier B.V. All rights reserved.

Reverse phase HPLC method for detection and quantification of lupin seed γ-conglutin.

PubMed

Mane, Sharmilee; Bringans, Scott; Johnson, Stuart; Pareek, Vishnu; Utikar, Ranjeet

2017-09-15

A simple, selective and accurate reverse phase HPLC method was developed for detection and quantitation of γ-conglutin from lupin seed extract. A linear gradient of water and acetonitrile containing trifluoroacetic acid (TFA) on a reverse phase column (Agilent Zorbax 300SB C-18), with a flow rate of 0.8ml/min was able to produce a sharp and symmetric peak of γ-conglutin with a retention time at 29.16min. The identity of γ-conglutin in the peak was confirmed by mass spectrometry (MS/MS identification) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The data obtained from MS/MS analysis was matched against the specified database to obtain the exact match for the protein of interest. The proposed method was validated in terms of specificity, linearity, sensitivity, precision, recovery and accuracy. The analytical parameters revealed that the validated method was capable of selectively performing a good chromatographic separation of γ-conglutin from the lupin seed extract with no interference of the matrix. The detection and quantitation limit of γ-conglutin were found to be 2.68μg/ml and 8.12μg/ml respectively. The accuracy (precision and recovery) analysis of the method was conducted under repeatable conditions on different days. Intra-day and inter-day precision values less than 0.5% and recovery greater than 97% indicated high precision and accuracy of the method for analysis of γ-conglutin. The method validation findings were reproducible and can be successfully applied for routine analysis of γ-conglutin from lupin seed extract. Copyright © 2017 Elsevier B.V. All rights reserved.

Correlation of the turbo-MP RIA with ImmunoCAP FEIA for determination of food allergen-specific immunoglobulin E.

PubMed

Kontis, Kris J; Valcour, Andre; Patel, Ashok; Chen, Andy; Wang, Jan; Chow, Julia; Nayak, Narayan

2006-01-01

It has been reported that in vitro measurement of food-specific IgE can be used to accurately predict food allergy and reduce the risk associated with double-blinded placebo-controlled food challenges (DBPCFC). Our objective was to assess the performance characteristics of the Hycor Turbo-MP quantitative radioimmunoassay for food-specific IgE and to determine this method's comparability to another assay, the Pharmacia ImmunoCAP fluorescence enzyme immunoassay (FEIA). The dynamic range of the Turbo-MP assay is 0.05 to 100 IU/ml, compared to 0.35 to 100 IU/ml for the FEIA. Performance characteristics of the Turbo-MP assay (ie, reproducibility of the calibration curve, within-run precision, total precision, parallelism, and linearity) were determined using samples from the Hycor serum bank. The precision (CV) of IgE calibrator replicates was <10%. The total precision (CV) of the Turbo-MP assay ranged from 8.8% to 18.4% for specific IgE concentrations between 0.28 to 31.4 IU/ml. Testing of serial dilutions of sera with IgE specificities for egg white, cow's milk, codfish, wheat, peanut, and soybean showed that the assay is linear over the entire dynamic range. Serial dilution data (slopes of 1.01 to 1.10) showed parallelism to serial dilutions of the IgE calibrator (slope of 0.96). The Turbo-MP and FEIA methods were both used for quantitative assays of food-specific IgE in 457 serum samples obtained from a clinical reference laboratory. Comparison of specific IgE results by the Turbo-MP and FEIA methods for 6 major food allergens exhibited a slope of 0.99 (0.92 to 1.03) with a correlation coefficient of 0.81.

Timing considerations for preclinical MRgRT: effects of ion diffusion, SNR and imaging times on FXG gel calibration

NASA Astrophysics Data System (ADS)

Welch, M.; Foltz, W. D.; Jaffray, D. A.

2015-01-01

Sub-millimeter resolution images are required for gel dosimeters to be used in preclinical research, which is challenging for MR probed ferrous xylenol-orange (FXG) dosimeters due to ion diffusion and inadequate SNR. A preclinical 7 T MR, small animal irradiator and FXG dosimeters were used in all experiments. Ion diffusion was analyzed using high resolution (0.2 mm/pixel) T1 MR images collected every 5 minutes, post-irradiation, for an hour. Using Fick's second law, ion diffusion was approximated for the first hour post-irradiation. SNR, T1 map precision and calibration fit were determined for two MR protocols: (1) 10 minute acquisition, 0.35mm/pixel and 3mm slices, (2) 45 minute acquisition, 0. 25 mm/pixel and 2 mm slices. SNR and T1 map precision were calculated using a Monte Carlo simulation. Calibration curves were determined by plotting R1 relaxation rates versus depth dose data, and fitting a linear trend line. Ion diffusion was estimated as 0.003mm2 in the first hour post-irradiation. For protocols (1) and (2) respectively, Monte Carlo simulation predicted T1 precisions of 3% and 5% within individual voxels using experimental SNRs; the corresponding measured T1 precisions were 8% and 12%. The linear trend lines reported slopes of 27 ± 3 Gy*s (R2: 0.80 ± 0.04) and 27 ± 4 Gy*s (R2: 0.90 ± 0.04). Ion diffusion is negligible within the first hour post-irradiation, and an accurate and reproducible calibration can be achieved in a preclinical setting with sub-millimeter resolution.

Quantification of strontium in human serum by ICP-MS using alternate analyte-free matrix and its application to a pilot bioequivalence study of two strontium ranelate oral formulations in healthy Chinese subjects.

PubMed

Zhang, Dan; Wang, Xiaolin; Liu, Man; Zhang, Lina; Deng, Ming; Liu, Huichen

2015-01-01

A rapid, sensitive and accurate ICP-MS method using alternate analyte-free matrix for calibration standards preparation and a rapid direct dilution procedure for sample preparation was developed and validated for the quantification of exogenous strontium (Sr) from the drug in human serum. Serum was prepared by direct dilution (1:29, v/v) in an acidic solution consisting of nitric acid (0.1%) and germanium (Ge) added as internal standard (IS), to obtain simple and high-throughput preparation procedure with minimized matrix effect, and good repeatability. ICP-MS analysis was performed using collision cell technology (CCT) mode. Alternate matrix method by using distilled water as an alternate analyte-free matrix for the preparation of calibration standards (CS) was used to avoid the influence of endogenous Sr in serum on the quantification. The method was validated in terms of selectivity, carry-over, matrix effects, lower limit of quantification (LLOQ), linearity, precision and accuracy, and stability. Instrumental linearity was verified in the range of 1.00-500ng/mL, corresponding to a concentration range of 0.0300-15.0μg/mL in 50μL sample of serum matrix and alternate matrix. Intra- and inter-day precision as relative standard deviation (RSD) were less than 8.0% and accuracy as relative error (RE) was within ±3.0%. The method allowed a high sample throughput, and was sensitive and accurate enough for a pilot bioequivalence study in healthy male Chinese subjects following single oral administration of two strontium ranelate formulations containing 2g strontium ranelate. Copyright © 2014 Elsevier GmbH. All rights reserved.

Assessment of Various Remote Sensing Technologies in Biomass and Nitrogen Content Estimation Using AN Agricultural Test Field

NASA Astrophysics Data System (ADS)

Näsi, R.; Viljanen, N.; Kaivosoja, J.; Hakala, T.; Pandžić, M.; Markelin, L.; Honkavaara, E.

2017-10-01

Multispectral and hyperspectral imaging is usually acquired by satellite and aircraft platforms. Recently, miniaturized hyperspectral 2D frame cameras have showed great potential to precise agriculture estimations and they are feasible to combine with lightweight platforms, such as drones. Drone platform is a flexible tool for remote sensing applications with environment and agriculture. The assessment and comparison of different platforms such as satellite, aircraft and drones with different sensors, such as hyperspectral and RGB cameras is an important task in order to understand the potential of the data provided by these equipment and to select the most appropriate according to the user applications and requirements. In this context, open and permanent test fields are very significant and helpful experimental environment, since they provide a comparative data for different platforms, sensors and users, allowing multi-temporal analyses as well. Objective of this work was to investigate the feasibility of an open permanent test field in context of precision agriculture. Satellite (Sentinel-2), aircraft and drones with hyperspectral and RGB cameras were assessed in this study to estimate biomass, using linear regression models and in-situ samples. Spectral data and 3D information were used and compared in different combinations to investigate the quality of the models. The biomass estimation accuracies using linear regression models were better than 90 % for the drone based datasets. The results showed that the use of spectral and 3D features together improved the estimation model. However, estimation of nitrogen content was less accurate with the evaluated remote sensing sensors. The open and permanent test field showed to be suitable to provide an accurate and reliable reference data for the commercial users and farmers.

Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS.

PubMed

Kappel, S; Boulyga, S F; Dorta, L; Günther, D; Hattendorf, B; Koffler, D; Laaha, G; Leisch, F; Prohaska, T

2013-03-01

Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector-inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'point-by-point', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'point-by-point' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP-7 test samples.

Value of Sample Return and High Precision Analyses: Need for A Resource of Compelling Stories, Metaphors and Examples for Public Speakers

NASA Technical Reports Server (NTRS)

Allton, J. H.

2017-01-01

There is widespread agreement among planetary scientists that much of what we know about the workings of the solar system comes from accurate, high precision measurements on returned samples. Precision is a function of the number of atoms the instrumentation is able to count. Accuracy depends on the calibration or standardization technique. For Genesis, the solar wind sample return mission, acquiring enough atoms to ensure precise SW measurements and then accurately quantifying those measurements were steps known to be non-trivial pre-flight. The difficulty of precise and accurate measurements on returned samples, and why they cannot be made remotely, is not communicated well to the public. In part, this is be-cause "high precision" is abstract and error bars are not very exciting topics. This paper explores ideas for collecting and compiling compelling metaphors and colorful examples as a resource for planetary science public speakers.

Experimental light scattering by small particles: system design and calibration

NASA Astrophysics Data System (ADS)

Maconi, Göran; Kassamakov, Ivan; Penttilä, Antti; Gritsevich, Maria; Hæggström, Edward; Muinonen, Karri

2017-06-01

We describe a setup for precise multi-angular measurements of light scattered by mm- to μm-sized samples. We present a calibration procedure that ensures accurate measurements. Calibration is done using a spherical sample (d = 5 mm, n = 1.517) fixed on a static holder. The ultimate goal of the project is to allow accurate multi-wavelength measurements (the full Mueller matrix) of single-particle samples which are levitated ultrasonically. The system comprises a tunable multimode Argon-krypton laser, with 12 wavelengths ranging from 465 to 676 nm, a linear polarizer, a reference photomultiplier tube (PMT) monitoring beam intensity, and several PMT:s mounted radially towards the sample at an adjustable radius. The current 150 mm radius allows measuring all azimuthal angles except for ±4° around the backward scattering direction. The measurement angle is controlled by a motor-driven rotational stage with an accuracy of 15'.

A Multiobjective Interval Programming Model for Wind-Hydrothermal Power System Dispatching Using 2-Step Optimization Algorithm

PubMed Central

Jihong, Qu

2014-01-01

Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision. PMID:24895663

A multiobjective interval programming model for wind-hydrothermal power system dispatching using 2-step optimization algorithm.

PubMed

Ren, Kun; Jihong, Qu

2014-01-01

Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision.

The preliminary exploration of 64-slice volume computed tomography in the accurate measurement of pleural effusion.

PubMed

Guo, Zhi-Jun; Lin, Qiang; Liu, Hai-Tao; Lu, Jun-Ying; Zeng, Yan-Hong; Meng, Fan-Jie; Cao, Bin; Zi, Xue-Rong; Han, Shu-Ming; Zhang, Yu-Huan

2013-09-01

Using computed tomography (CT) to rapidly and accurately quantify pleural effusion volume benefits medical and scientific research. However, the precise volume of pleural effusions still involves many challenges and currently does not have a recognized accurate measuring. To explore the feasibility of using 64-slice CT volume-rendering technology to accurately measure pleural fluid volume and to then analyze the correlation between the volume of the free pleural effusion and the different diameters of the pleural effusion. The 64-slice CT volume-rendering technique was used to measure and analyze three parts. First, the fluid volume of a self-made thoracic model was measured and compared with the actual injected volume. Second, the pleural effusion volume was measured before and after pleural fluid drainage in 25 patients, and the volume reduction was compared with the actual volume of the liquid extract. Finally, the free pleural effusion volume was measured in 26 patients to analyze the correlation between it and the diameter of the effusion, which was then used to calculate the regression equation. After using the 64-slice CT volume-rendering technique to measure the fluid volume of the self-made thoracic model, the results were compared with the actual injection volume. No significant differences were found, P = 0.836. For the 25 patients with drained pleural effusions, the comparison of the reduction volume with the actual volume of the liquid extract revealed no significant differences, P = 0.989. The following linear regression equation was used to compare the pleural effusion volume (V) (measured by the CT volume-rendering technique) with the pleural effusion greatest depth (d): V = 158.16 × d - 116.01 (r = 0.91, P = 0.000). The following linear regression was used to compare the volume with the product of the pleural effusion diameters (l × h × d): V = 0.56 × (l × h × d) + 39.44 (r = 0.92, P = 0.000). The 64-slice CT volume-rendering technique can accurately measure the volume in pleural effusion patients, and a linear regression equation can be used to estimate the volume of the free pleural effusion.

Determination of dasatinib in the tablet dosage form by ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis.

PubMed

Gonzalez, Aroa Garcia; Taraba, Lukáš; Hraníček, Jakub; Kozlík, Petr; Coufal, Pavel

2017-01-01

Dasatinib is a novel oral prescription drug proposed for treating adult patients with chronic myeloid leukemia. Three analytical methods, namely ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis, were developed, validated, and compared for determination of the drug in the tablet dosage form. The total analysis time of optimized ultra high performance liquid chromatography and capillary zone electrophoresis methods was 2.0 and 2.2 min, respectively. Direct ultraviolet detection with detection wavelength of 322 nm was employed in both cases. The optimized sequential injection analysis method was based on spectrophotometric detection of dasatinib after a simple colorimetric reaction with folin ciocalteau reagent forming a blue-colored complex with an absorbance maximum at 745 nm. The total analysis time was 2.5 min. The ultra high performance liquid chromatography method provided the lowest detection and quantitation limits and the most precise and accurate results. All three newly developed methods were demonstrated to be specific, linear, sensitive, precise, and accurate, providing results satisfactorily meeting the requirements of the pharmaceutical industry, and can be employed for the routine determination of the active pharmaceutical ingredient in the tablet dosage form. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rhombic micro-displacement amplifier for piezoelectric actuator and its linear and hybrid model

NASA Astrophysics Data System (ADS)

Chen, Jinglong; Zhang, Chunlin; Xu, Minglong; Zi, Yanyang; Zhang, Xinong

2015-01-01

This paper proposes rhombic micro-displacement amplifier (RMDA) for piezoelectric actuator (PA). First, the geometric amplification relations are analyzed and linear model is built to analyze the mechanical and electrical properties of this amplifier. Next, the accurate modeling method of amplifier is studied for important application of precise servo control. The classical Preisach model (CPM) is generally implemented using a numerical technique based on the first-order reversal curves (FORCs). The accuracy of CPM mainly depends on the number of FORCs. However, it is generally difficult to achieve enough number of FORCs in practice. So, Support Vector Machine (SVM) is employed in the work to circumvent the deficiency of the CPM. Then the hybrid model, which is based on discrete CPM and SVM is developed to account for hysteresis and dynamic effects. Finally, experimental validation is carried out. The analyzed result shows that this amplifier with the hybrid model is suitable for control application.

Experimental validation of flexible robot arm modeling and control

NASA Technical Reports Server (NTRS)

Ulsoy, A. Galip

1989-01-01

Flexibility is important for high speed, high precision operation of lightweight manipulators. Accurate dynamic modeling of flexible robot arms is needed. Previous work has mostly been based on linear elasticity with prescribed rigid body motions (i.e., no effect of flexible motion on rigid body motion). Little or no experimental validation of dynamic models for flexible arms is available. Experimental results are also limited for flexible arm control. Researchers include the effects of prismatic as well as revolute joints. They investigate the effect of full coupling between the rigid and flexible motions, and of axial shortening, and consider the control of flexible arms using only additional sensors.

Development and validation of a reversed-phase HPLC method for simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet dosage form.

PubMed

Shaikh, K A; Patil, S D; Devkhile, A B

2008-12-15

A simple, precise and accurate reversed-phase liquid chromatographic method has been developed for the simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet formulations. The chromatographic separation was achieved on a Xterra RP18 (250 mm x 4.6 mm, 5 microm) analytical column. A Mixture of acetonitrile-dipotassium phosphate (30 mM) (50:50, v/v) (pH 9.0) was used as the mobile phase, at a flow rate of 1.7 ml/min and detector wavelength at 215 nm. The retention time of ambroxol and azithromycin was found to be 5.0 and 11.5 min, respectively. The validation of the proposed method was carried out for specificity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness. The linear dynamic ranges were from 30-180 to 250-1500 microg/ml for ambroxol hydrochloride and azithromycin, respectively. The percentage recovery obtained for ambroxol hydrochloride and azithromycin were 99.40 and 99.90%, respectively. Limit of detection and quantification for azithromycin were 0.8 and 2.3 microg/ml, for ambroxol hydrochloride 0.004 and 0.01 microg/ml, respectively. The developed method can be used for routine quality control analysis of titled drugs in combination in tablet formulation.

Improving biomedical information retrieval by linear combinations of different query expansion techniques.

PubMed

Abdulla, Ahmed AbdoAziz Ahmed; Lin, Hongfei; Xu, Bo; Banbhrani, Santosh Kumar

2016-07-25

Biomedical literature retrieval is becoming increasingly complex, and there is a fundamental need for advanced information retrieval systems. Information Retrieval (IR) programs scour unstructured materials such as text documents in large reserves of data that are usually stored on computers. IR is related to the representation, storage, and organization of information items, as well as to access. In IR one of the main problems is to determine which documents are relevant and which are not to the user's needs. Under the current regime, users cannot precisely construct queries in an accurate way to retrieve particular pieces of data from large reserves of data. Basic information retrieval systems are producing low-quality search results. In our proposed system for this paper we present a new technique to refine Information Retrieval searches to better represent the user's information need in order to enhance the performance of information retrieval by using different query expansion techniques and apply a linear combinations between them, where the combinations was linearly between two expansion results at one time. Query expansions expand the search query, for example, by finding synonyms and reweighting original terms. They provide significantly more focused, particularized search results than do basic search queries. The retrieval performance is measured by some variants of MAP (Mean Average Precision) and according to our experimental results, the combination of best results of query expansion is enhanced the retrieved documents and outperforms our baseline by 21.06 %, even it outperforms a previous study by 7.12 %. We propose several query expansion techniques and their combinations (linearly) to make user queries more cognizable to search engines and to produce higher-quality search results.

Amesos2 and Belos: Direct and Iterative Solvers for Large Sparse Linear Systems

DOE PAGES

Bavier, Eric; Hoemmen, Mark; Rajamanickam, Sivasankaran; ...

2012-01-01

Solvers for large sparse linear systems come in two categories: direct and iterative. Amesos2, a package in the Trilinos software project, provides direct methods, and Belos, another Trilinos package, provides iterative methods. Amesos2 offers a common interface to many different sparse matrix factorization codes, and can handle any implementation of sparse matrices and vectors, via an easy-to-extend C++ traits interface. It can also factor matrices whose entries have arbitrary “Scalar” type, enabling extended-precision and mixed-precision algorithms. Belos includes many different iterative methods for solving large sparse linear systems and least-squares problems. Unlike competing iterative solver libraries, Belos completely decouples themore » algorithms from the implementations of the underlying linear algebra objects. This lets Belos exploit the latest hardware without changes to the code. Belos favors algorithms that solve higher-level problems, such as multiple simultaneous linear systems and sequences of related linear systems, faster than standard algorithms. The package also supports extended-precision and mixed-precision algorithms. Together, Amesos2 and Belos form a complete suite of sparse linear solvers.« less

Mapping the genome of meta-generalized gradient approximation density functionals: The search for B97M-V

NASA Astrophysics Data System (ADS)

Mardirossian, Narbe; Head-Gordon, Martin

2015-02-01

A meta-generalized gradient approximation density functional paired with the VV10 nonlocal correlation functional is presented. The functional form is selected from more than 1010 choices carved out of a functional space of almost 1040 possibilities. Raw data come from training a vast number of candidate functional forms on a comprehensive training set of 1095 data points and testing the resulting fits on a comprehensive primary test set of 1153 data points. Functional forms are ranked based on their ability to reproduce the data in both the training and primary test sets with minimum empiricism, and filtered based on a set of physical constraints and an often-overlooked condition of satisfactory numerical precision with medium-sized integration grids. The resulting optimal functional form has 4 linear exchange parameters, 4 linear same-spin correlation parameters, and 4 linear opposite-spin correlation parameters, for a total of 12 fitted parameters. The final density functional, B97M-V, is further assessed on a secondary test set of 212 data points, applied to several large systems including the coronene dimer and water clusters, tested for the accurate prediction of intramolecular and intermolecular geometries, verified to have a readily attainable basis set limit, and checked for grid sensitivity. Compared to existing density functionals, B97M-V is remarkably accurate for non-bonded interactions and very satisfactory for thermochemical quantities such as atomization energies, but inherits the demonstrable limitations of existing local density functionals for barrier heights.

Precision Linear Actuator for Space Interferometry Mission (SIM) Siderostat Pointing

NASA Technical Reports Server (NTRS)

Cook, Brant; Braun, David; Hankins, Steve; Koenig, John; Moore, Don

2008-01-01

'SIM PlanetQuest will exploit the classical measuring tool of astrometry (interferometry) with unprecedented precision to make dramatic advances in many areas of astronomy and astrophysics'(1). In order to obtain interferometric data two large steerable mirrors, or Siderostats, are used to direct starlight into the interferometer. A gimbaled mechanism actuated by linear actuators is chosen to meet the unprecedented pointing and angle tracking requirements of SIM. A group of JPL engineers designed, built, and tested a linear ballscrew actuator capable of performing submicron incremental steps for 10 years of continuous operation. Precise, zero backlash, closed loop pointing control requirements, lead the team to implement a ballscrew actuator with a direct drive DC motor and a precision piezo brake. Motor control commutation using feedback from a precision linear encoder on the ballscrew output produced an unexpected incremental step size of 20 nm over a range of 120 mm, yielding a dynamic range of 6,000,000:1. The results prove linear nanometer positioning requires no gears, levers, or hydraulic converters. Along the way many lessons have been learned and will subsequently be shared.

Evaluation of automated assays for immunoglobulin G, M, and A measurements in dog and cat serum.

PubMed

Tvarijonaviciute, Asta; Martínez-Subiela, Silvia; Caldin, Marco; Tecles, Fernando; Ceron, Jose J

2013-09-01

Measurements of immunoglobulins (Igs) in companion animals can be useful to detect deficiencies of the humoral immune system, that can be associated with opportunistic or chronic infections, or other immune-mediated disorders including B-cell neoplasms. The purpose of this study was to evaluate commercially available automated immunoturbidimetric assays designed for human IgG, M, and A measurements in canine and feline serum using species-specific calibrators. Canine and feline serum samples with different IgG, M, and A concentrations were used for the analytical validation of the assays. Intra- and inter-assay precision, linearity under dilution, spiking recovery, and limit of detection were determined. In addition, effects of lipemia, hemolysis, and bilirubinemia were evaluated. Finally, Ig concentrations were determined in small groups of diseased dogs and cats, and compared with healthy groups. Spiking recovery and linearity under dilution tests showed that the assays measured Igs in canine and feline serum samples precisely and accurately. Intra- and inter-assay imprecisions were lower than 15% in all cases. Significantly higher IgG, IgM, and IgA levels were observed in dogs with leishmaniasis, while dogs with pyometra showed a statistically significant increase in IgM and IgA concentrations in comparison with healthy dogs. Significantly higher IgG and IgM levels were observed in FIV-infected cats compared with healthy ones. The automated human Ig assays showed adequate precision and accuracy with serum samples from dogs and cats. Also, they were able to discriminate different concentrations of Igs in healthy and diseased animals. © 2013 American Society for Veterinary Clinical Pathology.

Validation of high throughput screening of human sera for detection of anti-PA IgG by Enzyme-Linked Immunosorbent Assay (ELISA) as an emergency response to an anthrax incident

PubMed Central

Semenova, Vera A.; Steward-Clark, Evelene; Maniatis, Panagiotis; Epperson, Monica; Sabnis, Amit; Schiffer, Jarad

2017-01-01

To improve surge testing capability for a response to a release of Bacillus anthracis, the CDC anti-Protective Antigen (PA) IgG Enzyme-Linked Immunosorbent Assay (ELISA) was re-designed into a high throughput screening format. The following assay performance parameters were evaluated: goodness of fit (measured as the mean reference standard r2), accuracy (measured as percent error), precision (measured as coefficient of variance (CV)), lower limit of detection (LLOD), lower limit of quantification (LLOQ), dilutional linearity, diagnostic sensitivity (DSN) and diagnostic specificity (DSP). The paired sets of data for each sample were evaluated by Concordance Correlation Coefficient (CCC) analysis. The goodness of fit was 0.999; percent error between the expected and observed concentration for each sample ranged from −4.6% to 14.4%. The coefficient of variance ranged from 9.0% to 21.2%. The assay LLOQ was 2.6 μg/mL. The regression analysis results for dilutional linearity data were r2 = 0.952, slope = 1.02 and intercept = −0.03. CCC between assays was 0.974 for the median concentration of serum samples. The accuracy and precision components of CCC were 0.997 and 0.977, respectively. This high throughput screening assay is precise, accurate, sensitive and specific. Anti-PA IgG concentrations determined using two different assays proved high levels of agreement. The method will improve surge testing capability 18-fold from 4 to 72 sera per assay plate. PMID:27814939

Theoretically guided analytical method development and validation for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometer

NASA Astrophysics Data System (ADS)

Khan, Mohammad F.; Rita, Shamima A.; Kayser, Md. Shahidulla; Islam, Md. Shariful; Asad, Sharmeen; Bin Rashid, Ridwan; Bari, Md. Abdul; Rahman, Muhammed M.; Al Aman, D. A. Anwar; Setu, Nurul I.; Banoo, Rebecca; Rashid, Mohammad A.

2017-04-01

A simple, rapid, economic, accurate and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0-8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λmax of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5 - 35.0 µg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 - 1.70% and 1.63 - 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 µg/mL, respectively. In addition, the developed method was successfully applied to assay rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh.

Spectrophotometric method development and validation for determination of chlorpheniramine maleate in bulk and controlled release tablets.

PubMed

Ashfaq, Maria; Sial, Ali Akber; Bushra, Rabia; Rehman, Atta-Ur; Baig, Mirza Tasawur; Huma, Ambreen; Ahmed, Maryam

2018-01-01

Spectrophotometric technique is considered to be the simplest and operator friendly among other available analytical methods for pharmaceutical analysis. The objective of the study was to develop a precise, accurate and rapid UV-spectrophotometric method for the estimation of chlorpheniramine maleate (CPM) in pure and solid pharmaceutical formulation. Drug absorption was measured in various solvent systems including 0.1N HCl (pH 1.2), acetate buffer (pH 4.5), phosphate buffer (pH 6.8) and distil water (pH 7.0). Method validation was performed as per official guidelines of ICH, 2005. High drug absorption was observed in 0.1N HCl medium with λ max of 261nm. The drug showed the good linearity from 20 to 60μg/mL solution concentration with the correlation coefficient linear regression equation Y= 0.1853 X + 0.1098 presenting R 2 value of 0.9998. The method accuracy was evaluated by the percent drug recovery, presents more than 99% drug recovery at three different levels assessed. The % RSD value <1 was computed for inter and intraday analysis indicating the high accuracy and precision of the developed technique. The developed method is robust because it shows no any significant variation in with minute changes. The LOD and LOQ values were assessed to be 2.2μg/mL and 6.6μg/mL respectively. The investigated method proved its sensitivity, precision and accuracy hence could be successfully used to estimate the CPM content in bulk and pharmaceutical matrix tablets.

Validation of high throughput screening of human sera for detection of anti-PA IgG by Enzyme-Linked Immunosorbent Assay (ELISA) as an emergency response to an anthrax incident.

PubMed

Semenova, Vera A; Steward-Clark, Evelene; Maniatis, Panagiotis; Epperson, Monica; Sabnis, Amit; Schiffer, Jarad

2017-01-01

To improve surge testing capability for a response to a release of Bacillus anthracis, the CDC anti-Protective Antigen (PA) IgG Enzyme-Linked Immunosorbent Assay (ELISA) was re-designed into a high throughput screening format. The following assay performance parameters were evaluated: goodness of fit (measured as the mean reference standard r 2 ), accuracy (measured as percent error), precision (measured as coefficient of variance (CV)), lower limit of detection (LLOD), lower limit of quantification (LLOQ), dilutional linearity, diagnostic sensitivity (DSN) and diagnostic specificity (DSP). The paired sets of data for each sample were evaluated by Concordance Correlation Coefficient (CCC) analysis. The goodness of fit was 0.999; percent error between the expected and observed concentration for each sample ranged from -4.6% to 14.4%. The coefficient of variance ranged from 9.0% to 21.2%. The assay LLOQ was 2.6 μg/mL. The regression analysis results for dilutional linearity data were r 2  = 0.952, slope = 1.02 and intercept = -0.03. CCC between assays was 0.974 for the median concentration of serum samples. The accuracy and precision components of CCC were 0.997 and 0.977, respectively. This high throughput screening assay is precise, accurate, sensitive and specific. Anti-PA IgG concentrations determined using two different assays proved high levels of agreement. The method will improve surge testing capability 18-fold from 4 to 72 sera per assay plate. Published by Elsevier Ltd.

Tunable diode laser in-situ CH4 measurements aboard the CARIBIC passenger aircraft: instrument performance assessment

NASA Astrophysics Data System (ADS)

Dyroff, C.; Zahn, A.; Sanati, S.; Christner, E.; Rauthe-Schöch, A.; Schuck, T. J.

2013-10-01

A laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft is presented. The instrument is based on a commercial Fast Greenhouse Gas Analyzer (FGGA, Los Gatos Res.), which was adapted to meet the requirements imposed by unattended airborne employment. The modified instrument is described. A laboratory characterization was performed to determine the instrument stability, precision, cross sensitivity to H2O, and accuracy. For airborne operation a calibration strategy is described, that utilizes CH4 measurements obtained from flask samples taken during the same flights. The precision of airborne measurements is 2 ppbv for 10 s averages. The accuracy at aircraft cruising altitude is 3.85 ppbv. During aircraft ascent and descent, where no flask samples were obtained, instrumental drifts can be less accurately considered and the uncertainty is estimated to be 12.4 ppbv. A linear humidity bias correction was applied to the CH4 measurements, which was most important in the lower troposphere. On average, the correction bias was around 6.5 ppbv at an altitude of 2 km, and negligible at cruising flight level. Observations from 103 long-distance flights are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere (UT/LMS), with occasional crossing of the tropics on flights to southern Africa. These accurate data mark the largest UT/LMS in-situ CH4 dataset worldwide. An example of a tracer-tracer correlation study with ozone is given, highlighting the possibility for accurate cross-tropopause transport analyses.

Tunable diode laser in-situ CH4 measurements aboard the CARIBIC passenger aircraft: instrument performance assessment

NASA Astrophysics Data System (ADS)

Dyroff, C.; Zahn, A.; Sanati, S.; Christner, E.; Rauthe-Schöch, A.; Schuck, T. J.

2014-03-01

A laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft is presented. The instrument is based on a commercial Fast Greenhouse Gas Analyser (FGGA, Los Gatos Res.), which was adapted to meet the requirements imposed by unattended airborne operation. It was characterised in the laboratory with respect to instrument stability, precision, cross sensitivity to H2O, and accuracy. For airborne operation, a calibration strategy is described that utilises CH4 measurements obtained from flask samples taken during the same flights. The precision of airborne measurements is 2 ppb for 10 s averages. The accuracy at aircraft cruising altitude is 3.85 ppb. During aircraft ascent and descent, where no flask samples were obtained, instrumental drifts can be less accurately determined and the uncertainty is estimated to be 12.4 ppb. A linear humidity bias correction was applied to the CH4 measurements, which was most important in the lower troposphere. On average, the correction bias was around 6.5 ppb at an altitude of 2 km, and negligible at cruising flight level. Observations from 103 long-distance flights are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere (UT/LMS), with occasional crossing of the tropics on flights to southern Africa. These accurate data mark the largest UT/LMS in-situ CH4 dataset worldwide. An example of a tracer-tracer correlation study with ozone is given, highlighting the possibility for accurate cross-tropopause transport analyses.

A Quantum Band Model of the nu3 Fundamental of Methanol (CH3OH) and Its Application to Fluorcescence Spectra of Comets

NASA Technical Reports Server (NTRS)

Villanueva, Geronimo L.; DiSanti, M. A.; Mumma, M. J.; Xu, L.-H.

2012-01-01

Methanol (CH3OH) radiates efficiently at infrared wavelengths, dominating the C-H stretching region in comets, yet inadequate quantum-mechanical models have imposed limits on the practical use of its emission spectra. Accordingly, we constructed a new line-by-line model for the 3 fundamental band of methanol at 2844 / cm (3.52 micron) and applied it to interpret cometary fluorescence spectra. The new model permits accurate synthesis of line-by-line spectra for a wide range of rotational temperatures, ranging from 10 K to more than 400 K.We validated the model by comparing simulations of CH3OH fluorescent emission with measured spectra of three comets (C/2001 A2 LINEAR, C/2004 Q2 Machholz and 8P/Tuttle) acquired with high-resolution infrared spectrometers at high-altitude sites. The new model accurately describes the complex emission spectrum of the nu3 band, providing distinct rotational temperatures and production rates at greatly improved confidence levels compared with results derived from earlier fluorescence models. The new model reconciles production rates measured at infrared and radio wavelengths in C/2001 A2 (LINEAR). Methanol can now be quantified with unprecedented precision and accuracy in astrophysical sources through high-dispersion spectroscopy at infrared wavelengths

Measurement of attenuation coefficients of the fundamental and second harmonic waves in water

NASA Astrophysics Data System (ADS)

Zhang, Shuzeng; Jeong, Hyunjo; Cho, Sungjong; Li, Xiongbing

2016-02-01

Attenuation corrections in nonlinear acoustics play an important role in the study of nonlinear fluids, biomedical imaging, or solid material characterization. The measurement of attenuation coefficients in a nonlinear regime is not easy because they depend on the source pressure and requires accurate diffraction corrections. In this work, the attenuation coefficients of the fundamental and second harmonic waves which come from the absorption of water are measured in nonlinear ultrasonic experiments. Based on the quasilinear theory of the KZK equation, the nonlinear sound field equations are derived and the diffraction correction terms are extracted. The measured sound pressure amplitudes are adjusted first for diffraction corrections in order to reduce the impact on the measurement of attenuation coefficients from diffractions. The attenuation coefficients of the fundamental and second harmonics are calculated precisely from a nonlinear least squares curve-fitting process of the experiment data. The results show that attenuation coefficients in a nonlinear condition depend on both frequency and source pressure, which are much different from a linear regime. In a relatively lower drive pressure, the attenuation coefficients increase linearly with frequency. However, they present the characteristic of nonlinear growth in a high drive pressure. As the diffraction corrections are obtained based on the quasilinear theory, it is important to use an appropriate source pressure for accurate attenuation measurements.

Development of a piezo-actuated micro-teleoperation system for cell manipulation.

PubMed

Zareinejad, M; Rezaei, S M; Abdullah, A; Shiry Ghidary, S

2009-03-01

Intracytoplasmic sperm injection (ICSI) requires long training and has low success rates, primarily due to poor control over the injection force. Making force feedback available to the operator will improve the success rate of the injection task. A macro-micro-teleoperation system bridges the gap between the task performed at the micro-level and the macroscopic movements of the operator. The teleoperation slave manipulator should accurately position a needle to precisely penetrate a cell membrane. Piezoelectric actuators are widely used in micromanipulation applications; however, hysteresis non-linearity limits the accuracy of these actuators. This paper presents a novel approach for utilizing a piezoelectric nano-stage as slave manipulator of a teleoperation system. The Prandtl-Ishlinskii (PI) model is used to model actuator hysteresis in a feedforward scheme to cancel out this non-linearity. To deal with the influence of parametric uncertainties, unmodelled dynamics and PI identification error, a perturbation term is added to the slave model and applies a sliding mode-based impedance control with perturbation estimation. The stability of entire system is guaranteed by Llewellyn's absolute stability criterion. The performance of the proposed controller was investigated through experiments for cell membrane penetration. The experimental results verified the accurate position tracking in free motion and simultaneous position and force tracking in contact with a low stiffness environment.

Novel linear piezoelectric motor for precision position stage

NASA Astrophysics Data System (ADS)

Chen, Chao; Shi, Yunlai; Zhang, Jun; Wang, Junshan

2016-03-01

Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus <0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.

Droplet Digital™ PCR Next-Generation Sequencing Library QC Assay.

PubMed

Heredia, Nicholas J

2018-01-01

Digital PCR is a valuable tool to quantify next-generation sequencing (NGS) libraries precisely and accurately. Accurately quantifying NGS libraries enable accurate loading of the libraries on to the sequencer and thus improve sequencing performance by reducing under and overloading error. Accurate quantification also benefits users by enabling uniform loading of indexed/barcoded libraries which in turn greatly improves sequencing uniformity of the indexed/barcoded samples. The advantages gained by employing the Droplet Digital PCR (ddPCR™) library QC assay includes the precise and accurate quantification in addition to size quality assessment, enabling users to QC their sequencing libraries with confidence.

THE MIRA–TITAN UNIVERSE: PRECISION PREDICTIONS FOR DARK ENERGY SURVEYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heitmann, Katrin; Habib, Salman; Biswas, Rahul

2016-04-01

Large-scale simulations of cosmic structure formation play an important role in interpreting cosmological observations at high precision. The simulations must cover a parameter range beyond the standard six cosmological parameters and need to be run at high mass and force resolution. A key simulation-based task is the generation of accurate theoretical predictions for observables using a finite number of simulation runs, via the method of emulation. Using a new sampling technique, we explore an eight-dimensional parameter space including massive neutrinos and a variable equation of state of dark energy. We construct trial emulators using two surrogate models (the linear powermore » spectrum and an approximate halo mass function). The new sampling method allows us to build precision emulators from just 26 cosmological models and to systematically increase the emulator accuracy by adding new sets of simulations in a prescribed way. Emulator fidelity can now be continuously improved as new observational data sets become available and higher accuracy is required. Finally, using one ΛCDM cosmology as an example, we study the demands imposed on a simulation campaign to achieve the required statistics and accuracy when building emulators for investigations of dark energy.« less

The mira-titan universe. Precision predictions for dark energy surveys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heitmann, Katrin; Bingham, Derek; Lawrence, Earl

2016-03-28

Large-scale simulations of cosmic structure formation play an important role in interpreting cosmological observations at high precision. The simulations must cover a parameter range beyond the standard six cosmological parameters and need to be run at high mass and force resolution. A key simulation-based task is the generation of accurate theoretical predictions for observables using a finite number of simulation runs, via the method of emulation. Using a new sampling technique, we explore an eight-dimensional parameter space including massive neutrinos and a variable equation of state of dark energy. We construct trial emulators using two surrogate models (the linear powermore » spectrum and an approximate halo mass function). The new sampling method allows us to build precision emulators from just 26 cosmological models and to systematically increase the emulator accuracy by adding new sets of simulations in a prescribed way. Emulator fidelity can now be continuously improved as new observational data sets become available and higher accuracy is required. Finally, using one ΛCDM cosmology as an example, we study the demands imposed on a simulation campaign to achieve the required statistics and accuracy when building emulators for investigations of dark energy.« less

Application of Smart Infrastructure Systems approach to precision medicine.

PubMed

Govindaraju, Diddahally R; Annaswamy, Anuradha M

2015-12-01

All biological variation is hierarchically organized dynamic network system of genomic components, organelles, cells, tissues, organs, individuals, families, populations and metapopulations. Individuals are axial in this hierarchy, as they represent antecedent, attendant and anticipated aspects of health, disease, evolution and medical care. Humans show individual specific genetic and clinical features such as complexity, cooperation, resilience, robustness, vulnerability, self-organization, latent and emergent behavior during their development, growth and senescence. Accurate collection, measurement, organization and analyses of individual specific data, embedded at all stratified levels of biological, demographic and cultural diversity - the big data - is necessary to make informed decisions on health, disease and longevity; which is a central theme of precision medicine initiative (PMI). This initiative also calls for the development of novel analytical approaches to handle complex multidimensional data. Here we suggest the application of Smart Infrastructure Systems (SIS) approach to accomplish some of the goals set forth by the PMI on the premise that biological systems and the SIS share many common features. The latter has been successfully employed in managing complex networks of non-linear adaptive controls, commonly encountered in smart engineering systems. We highlight their concordance and discuss the utility of the SIS approach in precision medicine programs.

A comparative study of smart spectrophotometric methods for simultaneous determination of a skeletal muscle relaxant and an analgesic in combined dosage form.

PubMed

Salem, Hesham; Mohamed, Dalia

2015-04-05

Six simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the analgesic drug; paracetamol (PARA) and the skeletal muscle relaxant; dantrolene sodium (DANT). Three methods are manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and mean centering (MC). The other three methods are utilizing the isoabsorptive point either at zero order namely; absorbance ratio (AR) and absorbance subtraction (AS) or at ratio spectrum namely; amplitude modulation (AM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and capsules. The obtained results were statistically compared with each other and with those of reported spectrophotometric ones. The comparison showed that there is no significant difference between the proposed methods and the reported methods regarding both accuracy and precision. Copyright © 2015 Elsevier B.V. All rights reserved.

Validation of a LC/MS method for the determination of gemfibrozil in human plasma and its application to a pharmacokinetic study

PubMed Central

Rower, Joseph E.; Bushman, Lane R.; Hammond, Kyle P.; Kadam, Rajendra S.; Aquilante, Christina L.

2011-01-01

Gemfibrozil, a fibric acid hypolipidemic agent, is increasingly being used in clinical drug-drug interaction studies as an inhibitor of drug metabolizing enzymes and drug transporters. The validation of a fast, accurate, and precise LC/MS method is described for the quantitative determination of gemfibrozil in an EDTA-anticoagulated human plasma matrix. Briefly, gemfibrozil was extracted from human plasma by an acetonitrile protein precipitation method. The assay was reproducible with intra-assay precision between 1.6% and 10.7%, and inter-assay precision ranging from 4.4% to 7.8%. The assay also showed good accuracy, with intra-assay concentrations within 85.6% and 108.7% of the expected value, and inter-assay concentrations within 89.4 to 104.0% of the expected value. The linear concentration range was between 0.5 and 50 μg/mL with a lower limit of quantitation of 0.5 μg/mL when 125 μL of plasma were extracted. This LC/MS method yielded a quick, simple, and reliable protocol for determining gemfibrozil concentrations in plasma and is applicable to clinical pharmacokinetic studies. PMID:21077249

Validation of an LC/MS method for the determination of gemfibrozil in human plasma and its application to a pharmacokinetic study.

PubMed

Rower, Joseph E; Bushman, Lane R; Hammond, Kyle P; Kadam, Rajendra S; Aquilante, Christina L

2010-12-01

Gemfibrozil, a fibric acid hypolipidemic agent, is increasingly being used in clinical drug-drug interaction studies as an inhibitor of drug metabolizing enzymes and drug transporters. The validation of a fast, accurate and precise LC/MS method is described for the quantitative determination of gemfibrozil in an EDTA-anticoagulated human plasma matrix. Briefly, gemfibrozil was extracted from human plasma by an acetonitrile protein precipitation method. The assay was reproducible with intra-assay precision between 1.6 and 10.7%, and inter-assay precision ranging from 4.4 to 7.8%. The assay also showed good accuracy, with intra-assay concentrations within 85.6-108.7% of the expected value, and inter-assay concentrations within 89.4-104.0% of the expected value. The linear concentration range was between 0.5 and 50 µg/mL with a lower limit of quantitation of 0.5 µg/mL when 125 µL of plasma were extracted. This LC/MS method yielded a quick, simple and reliable protocol for determining gemfibrozil concentrations in plasma and is applicable to clinical pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd.

Linearity, Bias, and Precision of Hepatic Proton Density Fat Fraction Measurements by Using MR Imaging: A Meta-Analysis.

PubMed

Yokoo, Takeshi; Serai, Suraj D; Pirasteh, Ali; Bashir, Mustafa R; Hamilton, Gavin; Hernando, Diego; Hu, Houchun H; Hetterich, Holger; Kühn, Jens-Peter; Kukuk, Guido M; Loomba, Rohit; Middleton, Michael S; Obuchowski, Nancy A; Song, Ji Soo; Tang, An; Wu, Xinhuai; Reeder, Scott B; Sirlin, Claude B

2018-02-01

Purpose To determine the linearity, bias, and precision of hepatic proton density fat fraction (PDFF) measurements by using magnetic resonance (MR) imaging across different field strengths, imager manufacturers, and reconstruction methods. Materials and Methods This meta-analysis was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic literature search identified studies that evaluated the linearity and/or bias of hepatic PDFF measurements by using MR imaging (hereafter, MR imaging-PDFF) against PDFF measurements by using colocalized MR spectroscopy (hereafter, MR spectroscopy-PDFF) or the precision of MR imaging-PDFF. The quality of each study was evaluated by using the Quality Assessment of Studies of Diagnostic Accuracy 2 tool. De-identified original data sets from the selected studies were pooled. Linearity was evaluated by using linear regression between MR imaging-PDFF and MR spectroscopy-PDFF measurements. Bias, defined as the mean difference between MR imaging-PDFF and MR spectroscopy-PDFF measurements, was evaluated by using Bland-Altman analysis. Precision, defined as the agreement between repeated MR imaging-PDFF measurements, was evaluated by using a linear mixed-effects model, with field strength, imager manufacturer, reconstruction method, and region of interest as random effects. Results Twenty-three studies (1679 participants) were selected for linearity and bias analyses and 11 studies (425 participants) were selected for precision analyses. MR imaging-PDFF was linear with MR spectroscopy-PDFF (R 2 = 0.96). Regression slope (0.97; P < .001) and mean Bland-Altman bias (-0.13%; 95% limits of agreement: -3.95%, 3.40%) indicated minimal underestimation by using MR imaging-PDFF. MR imaging-PDFF was precise at the region-of-interest level, with repeatability and reproducibility coefficients of 2.99% and 4.12%, respectively. Field strength, imager manufacturer, and reconstruction method each had minimal effects on reproducibility. Conclusion MR imaging-PDFF has excellent linearity, bias, and precision across different field strengths, imager manufacturers, and reconstruction methods. © RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on October 2, 2017.

MISR CMVs and Multiangular Views of Tropical Cyclone Inner-Core Dynamics

NASA Technical Reports Server (NTRS)

Wu, Dong L.; Diner, David J.; Garay, Michael J; Jovanovic, Veljko M.; Lee, Jae N.; Moroney, Catherine M.; Mueller, Kevin J.; Nelson, David L.

2010-01-01

Multi-camera stereo imaging of cloud features from the MISR (Multiangle Imaging SpectroRadiometer) instrument on NASA's Terra satellite provides accurate and precise measurements of cloud top heights (CTH) and cloud motion vector (CMV) winds. MISR observes each cloudy scene from nine viewing angles (Nadir, +/-26(sup o), +/-46(sup o), +/-60(sup o), +/-70(sup o)) with approximatel 275-m pixel resolution. This paper provides an update on MISR CMV and CTH algorithm improvements, and explores a high-resolution retrieval of tangential winds inside the eyewall of tropical cyclones (TC). The MISR CMV and CTH retrievals from the updated algorithm are significantly improved in terms of spatial coverage and systematic errors. A new product, the 1.1-km cross-track wind, provides high accuracy and precision in measuring convective outflows. Preliminary results obtained from the 1.1-km tangential wind retrieval inside the TC eyewall show that the inner-core rotation is often faster near the eyewall, and this faster rotation appears to be related linearly to cyclone intensity.

Simultaneous determination of diclofenac potassium and methocarbamol in ternary mixture with guaifenesin by reversed phase liquid chromatography.

PubMed

Elkady, Ehab F

2010-09-15

New, simple, rapid and precise reversed phase liquid chromatographic (RP-LC) method has been developed for the simultaneous determination of diclofenac potassium (DP) and methocarbamol (MT) in ternary mixture with guaifenesin (GF), degradation product of methocarbamol. Chromatographic separation was achieved on a Symmetry Waters C18 column (150 mm x 4. 6mm, 5 microm). Gradient elution based on phosphate buffer pH (8)-acetonitrile at a flow rate of 1 mL min(-1) was applied. The UV detector was operated at 282 nm for DP and 274 nm for MT and GF. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.05-16, 0.5-160 and 0.5-160 microg mL(-1) for DP, MT and GF, respectively. The optimized method proved to be specific, robust and accurate for the quality control of the cited drugs in pharmaceutical preparation. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Offset-frequency locking of extended-cavity diode lasers for precision spectroscopy of water at 1.38 μm.

PubMed

Gianfrani, Livio; Castrillo, Antonio; Fasci, Eugenio; Galzerano, Gianluca; Casa, Giovanni; Laporta, Paolo

2010-10-11

We describe a continuous-wave diode laser spectrometer for water-vapour precision spectroscopy at 1.38 μm. The spectrometer is based upon the use of a simple scheme for offset-frequency locking of a pair of extended-cavity diode lasers that allows to achieve unprecedented accuracy and reproducibility levels in measuring molecular absorption. When locked to the master laser with an offset frequency of 1.5 GHz, the slave laser exhibits residual frequency fluctuations of 1 kHz over a time interval of 25 minutes, for a 1-s integration time. The slave laser could be continuously tuned up to 3 GHz, the scan showing relative deviations from linearity below the 10{-6} level. Simultaneously, a capture range of the order of 1 GHz was obtained. Quantitative spectroscopy was also demonstrated by accurately determining relevant spectroscopic parameters for the 22,1→22,0line of the H2(18)O v1+v3 band at 1384.6008 nm.

Quantification of Hydroxychloroquine in Blood Using Turbulent Flow Liquid Chromatography-Tandem Mass Spectrometry (TFLC-MS/MS).

PubMed

Chambliss, Allison B; Füzéry, Anna K; Clarke, William A

2016-01-01

Hydroxychloroquine (HQ) is used routinely in the treatment of autoimmune disorders such as rheumatoid arthritis and lupus erythematosus. Issues such as marked pharmacokinetic variability and patient non-compliance make therapeutic drug monitoring of HQ a useful tool for management of patients taking this drug. Quantitative measurements of HQ may aid in identifying poor efficacy as well as provide reliable information to distinguish patient non-compliance from refractory disease. We describe a rapid 7-min assay for the accurate and precise measurement of HQ concentrations in 100 μL samples of human blood using turbulent flow liquid chromatography coupled to tandem mass spectrometry. HQ is isolated from EDTA whole blood after a simple extraction with its deuterated analog, hydroxychloroquine-d4, in 0.33 M perchloric acid. Samples are then centrifuged and injected onto the TFLC-MS/MS system. Quantification is performed using a nine-point calibration curve that is linear over a wide range (15.7-4000 ng/mL) with precisions of <5 %.

Simultaneous quantification of withanolides in Withania somnifera by a validated high-performance thin-layer chromatographic method.

PubMed

Srivastava, Pooja; Tiwari, Neerja; Yadav, Akhilesh K; Kumar, Vijendra; Shanker, Karuna; Verma, Ram K; Gupta, Madan M; Gupta, Anil K; Khanuja, Suman P S

2008-01-01

This paper describes a sensitive, selective, specific, robust, and validated densitometric high-performance thin-layer chromatographic (HPTLC) method for the simultaneous determination of 3 key withanolides, namely, withaferin-A, 12-deoxywithastramonolide, and withanolide-A, in Ashwagandha (Withania somnifera) plant samples. The separation was performed on aluminum-backed silica gel 60F254 HPTLC plates using dichloromethane-methanol-acetone-diethyl ether (15 + 1 + 1 + 1, v/v/v/v) as the mobile phase. The withanolides were quantified by densitometry in the reflection/absorption mode at 230 nm. Precise and accurate quantification could be performed in the linear working concentration range of 66-330 ng/band with good correlation (r2 = 0.997, 0.999, and 0.996, respectively). The method was validated for recovery, precision, accuracy, robustness, limit of detection, limit of quantitation, and specificity according to International Conference on Harmonization guidelines. Specificity of quantification was confirmed using retention factor (Rf) values, UV-Vis spectral correlation, and electrospray ionization mass spectra of marker compounds in sample tracks.

Research on accuracy analysis of laser transmission system based on Zemax and Matlab

NASA Astrophysics Data System (ADS)

Chen, Haiping; Liu, Changchun; Ye, Haixian; Xiong, Zhao; Cao, Tingfen

2017-05-01

Laser transmission system is important in high power solid-state laser facilities and its function is to transfer and focus the light beam in accordance with the physical function of the facility. This system is mainly composed of transmission mirror modules and wedge lens module. In order to realize the precision alignment of the system, the precision alignment of the system is required to be decomposed into the allowable range of the calibration error of each module. The traditional method is to analyze the error factors of the modules separately, and then the linear synthesis is carried out, and the influence of the multi-module and multi-factor is obtained. In order to analyze the effect of the alignment error of each module on the beam center and focus more accurately, this paper aims to combine with the Monte Carlo random test and ray tracing, analyze influence of multi-module and multi-factor on the center of the beam, and evaluate and optimize the results of accuracy decomposition.

Assessment of Gamma-Ray-Spectra Analysis Method Utilizing the Fireworks Algorithm for Various Error Measures

DOE PAGES

Alamaniotis, Miltiadis; Tsoukalas, Lefteri H.

2018-01-01

The analysis of measured data plays a significant role in enhancing nuclear nonproliferation mainly by inferring the presence of patterns associated with special nuclear materials. Among various types of measurements, gamma-ray spectra is the widest utilized type of data in nonproliferation applications. In this paper, a method that employs the fireworks algorithm (FWA) for analyzing gamma-ray spectra aiming at detecting gamma signatures is presented. In particular, FWA is utilized to fit a set of known signatures to a measured spectrum by optimizing an objective function, where non-zero coefficients express the detected signatures. FWA is tested on a set of experimentallymore » obtained measurements optimizing various objective functions—MSE, RMSE, Theil-2, MAE, MAPE, MAP—with results exhibiting its potential in providing highly accurate and precise signature detection. Finally and furthermore, FWA is benchmarked against genetic algorithms and multiple linear regression, showing its superiority over those algorithms regarding precision with respect to MAE, MAPE, and MAP measures.« less

Determination of rifampicin in human plasma by high-performance liquid chromatography coupled with ultraviolet detection after automatized solid-liquid extraction.

PubMed

Louveau, B; Fernandez, C; Zahr, N; Sauvageon-Martre, H; Maslanka, P; Faure, P; Mourah, S; Goldwirt, L

2016-12-01

A precise and accurate high-performance liquid chromatography (HPLC) quantification method of rifampicin in human plasma was developed and validated using ultraviolet detection after an automatized solid-phase extraction. The method was validated with respect to selectivity, extraction recovery, linearity, intra- and inter-day precision, accuracy, lower limit of quantification and stability. Chromatographic separation was performed on a Chromolith RP 8 column using a mixture of 0.05 m acetate buffer pH 5.7-acetonitrile (35:65, v/v) as mobile phase. The compounds were detected at a wavelength of 335 nm with a lower limit of quantification of 0.05 mg/L in human plasma. Retention times for rifampicin and 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline used as internal standard were respectively 3.77 and 4.81 min. This robust and exact method was successfully applied in routine for therapeutic drug monitoring in patients treated with rifampicin. Copyright © 2016 John Wiley & Sons, Ltd.

A validated high-performance liquid chromatographic method for the determination of glibenclamide in human plasma and its application to pharmacokinetic studies.

PubMed

Niopas, Ioannis; Daftsios, Athanasios C

2002-05-15

Glibenclamide is a potent second generation oral sulfonylurea antidiabetic agent widely used for the treatment of type II diabetes melitus. A rapid, sensitive, precise, accurate and specific HPLC assay for the determination of glibenclamide in human plasma was developed and validated. After addition of flufenamic acid as internal standard, the analytes were isolated from human plasma by liquid-liquid extraction. The method was linear in the 10-400 ng/ml concentration range (r > 0.999). Recovery for glibenclamide was greater than 91.5% and for internal standard was 93.5%. Within-day and between-day precision, expressed as the relative standard deviation (RSD%), ranged from 1.4 to 5.9% and 5.8 to 6.6%, respectively. Assay accuracy was better than 93.4%. The assay was used to estimate the pharmacokinetics of glibenclamide after oral administration of a 5 mg tablet of glibenclamide to 18 healthy volunteers.

Simultaneous determination of a binary mixture of pantoprazole sodium and itopride hydrochloride by four spectrophotometric methods.

PubMed

Ramadan, Nesrin K; El-Ragehy, Nariman A; Ragab, Mona T; El-Zeany, Badr A

2015-02-25

Four simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of a binary mixture containing Pantoprazole Sodium Sesquihydrate (PAN) and Itopride Hydrochloride (ITH). Method (A) is the derivative ratio method ((1)DD), method (B) is the mean centering of ratio spectra method (MCR), method (C) is the ratio difference method (RD) and method (D) is the isoabsorptive point coupled with third derivative method ((3)D). Linear correlation was obtained in range 8-44 μg/mL for PAN by the four proposed methods, 8-40 μg/mL for ITH by methods A, B and C and 10-40 μg/mL for ITH by method D. The suggested methods were validated according to ICH guidelines. The obtained results were statistically compared with those obtained by the official and a reported method for PAN and ITH, respectively, showing no significant difference with respect to accuracy and precision. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous determination of a binary mixture of pantoprazole sodium and itopride hydrochloride by four spectrophotometric methods

NASA Astrophysics Data System (ADS)

Ramadan, Nesrin K.; El-Ragehy, Nariman A.; Ragab, Mona T.; El-Zeany, Badr A.

2015-02-01

Four simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of a binary mixture containing Pantoprazole Sodium Sesquihydrate (PAN) and Itopride Hydrochloride (ITH). Method (A) is the derivative ratio method (1DD), method (B) is the mean centering of ratio spectra method (MCR), method (C) is the ratio difference method (RD) and method (D) is the isoabsorptive point coupled with third derivative method (3D). Linear correlation was obtained in range 8-44 μg/mL for PAN by the four proposed methods, 8-40 μg/mL for ITH by methods A, B and C and 10-40 μg/mL for ITH by method D. The suggested methods were validated according to ICH guidelines. The obtained results were statistically compared with those obtained by the official and a reported method for PAN and ITH, respectively, showing no significant difference with respect to accuracy and precision.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

USGS Publications Warehouse

McLain, B.J.

1993-01-01

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

Parameters Identification for Photovoltaic Module Based on an Improved Artificial Fish Swarm Algorithm

PubMed Central

Wang, Hong-Hua

2014-01-01

A precise mathematical model plays a pivotal role in the simulation, evaluation, and optimization of photovoltaic (PV) power systems. Different from the traditional linear model, the model of PV module has the features of nonlinearity and multiparameters. Since conventional methods are incapable of identifying the parameters of PV module, an excellent optimization algorithm is required. Artificial fish swarm algorithm (AFSA), originally inspired by the simulation of collective behavior of real fish swarms, is proposed to fast and accurately extract the parameters of PV module. In addition to the regular operation, a mutation operator (MO) is designed to enhance the searching performance of the algorithm. The feasibility of the proposed method is demonstrated by various parameters of PV module under different environmental conditions, and the testing results are compared with other studied methods in terms of final solutions and computational time. The simulation results show that the proposed method is capable of obtaining higher parameters identification precision. PMID:25243233

Gravitational starlight deflection measurements during the 21 August 2017 total solar eclipse

NASA Astrophysics Data System (ADS)

Bruns, Donald G.

2018-04-01

Precise star positions near the Sun were measured during the 21 August 2017 total solar eclipse in order to measure their gravitational deflections. The equipment, procedures, and analysis are described in detail. A portable refractor, a CCD camera, and a computerized mount were set up in Wyoming. Detailed calibrations were necessary to improve accuracy and precision. Nighttime measurements taken just before the eclipse provided cubic optical distortion corrections. Calibrations based on star field images 7.4° on both sides of the Sun taken during totality gave linear and quadratic plate constants. A total of 45 images of the sky surrounding the Sun were acquired during the middle part of totality, with an integrated exposure of 22 s. The deflection analysis depended on accurate star positions from the USNO’s UCAC5 star catalog. The final result was a deflection coefficient L  =  1.7512 arcsec, in perfect agreement with the theoretical value, with an uncertainty of only 3%.

Feasibility study of a photoconductor based dosimeter for quality assurance in radiotherapy

NASA Astrophysics Data System (ADS)

Lee, Y. K.; Kim, S. W.; Kim, J. N.; Kang, Y. N.; Kim, J. Y.; Lee, D. S.; Kim, K. T.; Han, M. J.; Ahn, K. J.; Park, S. K.

2017-09-01

With the recent market entries of new types of linear accelerators (LINACs) with a multi leaf collimator (MLC) mounted on them, high-precision radiosurgery applying a LINAC to measure high-dose radiation on the target region has been gaining popularity. Systematic and accurate quality assurance (QA) is of vital important for high-precision radiosurgery because of its increased risk of side effects including life-threatening ones such as overexposure of healthy tissues to high-dose radiation beams concentrated on small areas. Therefore, accurate dose and dose-distribution measurements are crucial in the treatment procedure. The accurate measurement of the properties of beams concentrated on small areas requires high-precision dosimeters capable of high-resolution output and dose mapping as well as accurate dosimetry in penumbra regions. In general, the properties of beams concentrated on small areas are measured using thermos luminescent dosimeters (TLD), diode detectors, ion chambers, diamond detectors, or films, and many papers have presented the advantages and disadvantages of each of these detectors for dosimetry. In this study, a solid-state photoconductor dosimeter was developed, and its clinical usability was tested by comparing its relative dosimetric performance with that of a conventional ion chamber. As materials best-suited for radiation dosimeters, four candidates namely lead (II) iodide (PbI2), lead (II) oxide (PbO), mercury (II) iodide (HgI2), and HgI2/ titanium dioxide (TiO2) composite, the performances of which were proved in previous studies, were used. The electrical properties of each candidate material were examined using the sedimentation method, one of the particle-in-binder (PIB) methods, and unit-cell-type prototypes were fabricated. The unit-cell samples thus prepared were cut into specimens of area 1 × 1 cm2 with 400-μ m thickness. The electrical properties of each sample, such as sensitivity, dark current, output current, rising time, falling time, and response delay, were then measured, in addition to the consistency, reproducibility and linearity of each unit-cell. According to the measurement results, HgI2/TiO2 composite outperformed the other candidate materials. A radiation dosimeter with a chamber-type structure was fabricated in this study using a LINAC under accelerating voltages of 6, and 15 MV and compared with a commercial ion chamber. Percent depth dose (PDD) and beam profile were measured on a water phantom at a fixed area of 10 × 10 cm2 by using the fabricated chamber-type dosimeter, and the values were compared with those measured by a commercial ion chamber. Additionally, a homogeneous phantom was fabricated, and the exposure doses of the center points were measured according to a real treatment plan, followed by a comparison of the measured values as relative values. In this paper, we report that the manufactured dosimeter shows similar characteristics in terms of PDD and beam profile and results for the conventional ion chamber. Based on these results, it is demonstrated that the HgI2/TiO2-based dosimeter complies with radiotherapy QA requirements, namely Superior detection characteristics, consistency, dose linearity, reproducibility. Thus, we expect the HgI2/TiO2-based dosimeter to be used commercially in the future.

Statistical analysis of an RNA titration series evaluates microarray precision and sensitivity on a whole-array basis

PubMed Central

Holloway, Andrew J; Oshlack, Alicia; Diyagama, Dileepa S; Bowtell, David DL; Smyth, Gordon K

2006-01-01

Background Concerns are often raised about the accuracy of microarray technologies and the degree of cross-platform agreement, but there are yet no methods which can unambiguously evaluate precision and sensitivity for these technologies on a whole-array basis. Results A methodology is described for evaluating the precision and sensitivity of whole-genome gene expression technologies such as microarrays. The method consists of an easy-to-construct titration series of RNA samples and an associated statistical analysis using non-linear regression. The method evaluates the precision and responsiveness of each microarray platform on a whole-array basis, i.e., using all the probes, without the need to match probes across platforms. An experiment is conducted to assess and compare four widely used microarray platforms. All four platforms are shown to have satisfactory precision but the commercial platforms are superior for resolving differential expression for genes at lower expression levels. The effective precision of the two-color platforms is improved by allowing for probe-specific dye-effects in the statistical model. The methodology is used to compare three data extraction algorithms for the Affymetrix platforms, demonstrating poor performance for the commonly used proprietary algorithm relative to the other algorithms. For probes which can be matched across platforms, the cross-platform variability is decomposed into within-platform and between-platform components, showing that platform disagreement is almost entirely systematic rather than due to measurement variability. Conclusion The results demonstrate good precision and sensitivity for all the platforms, but highlight the need for improved probe annotation. They quantify the extent to which cross-platform measures can be expected to be less accurate than within-platform comparisons for predicting disease progression or outcome. PMID:17118209

Performance and System Validation of a New Cellular-Enabled Blood Glucose Monitoring System Using a New Standard Reference Measurement Procedure of Isotope Dilution UPLC-MRM Mass Spectrometry

PubMed Central

Angelides, Kimon; Matsunami, Risë K.; Engler, David A.

2015-01-01

Background: We evaluated the accuracy, precision, and linearity of the In Touch® blood glucose monitoring system (BGMS), a new color touch screen and cellular-enabled blood glucose meter, using a new rapid, highly precise and accurate 13C6 isotope-dilution liquid chromatography-mass spectrometry method (IDLC-MS). Methods: Blood glucose measurements from the In Touch® BGMS were referenced to a validated UPLC-MRM standard reference measurement procedure previously shown to be highly accurate and precise. Readings from the In Touch® BGMS were taken over the blood glucose range of 24-640 mg/dL using 12 concentrations of blood glucose. Ten In Touch® BGMS and 3 lots of test strips were used with 10 replicates at each concentration. A lay user study was also performed to assess the ease of use. Results: At blood glucose concentrations <75 mg/dL 100% of the measurements are within ±8 mg/dL from the true reference standard; at blood glucose levels >75 mg/dL 100% of the measurements are within ±15% of the true reference standard. 100% of the results are within category A of the consensus grid. Within-run precision show CV < 3.72% between 24-50 mg/dL and CV<2.22% between 500 and 600 mg/dL. The results show that the In Touch® meter exceeds the minimum criteria of both the ISO 15197:2003 and ISO 15197:2013 standards. The results from a user panel show that 100% of the respondents reported that the color touch screen, with its graphic user interface (GUI), is well labeled and easy to navigate. Conclusions: To our knowledge this is the first touch screen glucose meter and the first study where accuracy of a new BGMS has been measured against a true primary reference standard, namely IDLC-MS. PMID:26002836

Correcting the spectroscopic surface gravity using transits and asteroseismology. No significant effect on temperatures or metallicities with ARES and MOOG in local thermodynamic equilibrium

NASA Astrophysics Data System (ADS)

Mortier, A.; Sousa, S. G.; Adibekyan, V. Zh.; Brandão, I. M.; Santos, N. C.

2014-12-01

Context. Precise stellar parameters (effective temperature, surface gravity, metallicity, stellar mass, and radius) are crucial for several reasons, amongst which are the precise characterization of orbiting exoplanets and the correct determination of galactic chemical evolution. The atmospheric parameters are extremely important because all the other stellar parameters depend on them. Using our standard equivalent-width method on high-resolution spectroscopy, good precision can be obtained for the derived effective temperature and metallicity. The surface gravity, however, is usually not well constrained with spectroscopy. Aims: We use two different samples of FGK dwarfs to study the effect of the stellar surface gravity on the precise spectroscopic determination of the other atmospheric parameters. Furthermore, we present a straightforward formula for correcting the spectroscopic surface gravities derived by our method and with our linelists. Methods: Our spectroscopic analysis is based on Kurucz models in local thermodynamic equilibrium, performed with the MOOG code to derive the atmospheric parameters. The surface gravity was either left free or fixed to a predetermined value. The latter is either obtained through a photometric transit light curve or derived using asteroseismology. Results: We find first that, despite some minor trends, the effective temperatures and metallicities for FGK dwarfs derived with the described method and linelists are, in most cases, only affected within the errorbars by using different values for the surface gravity, even for very large differences in surface gravity, so they can be trusted. The temperatures derived with a fixed surface gravity continue to be compatible within 1 sigma with the accurate results of the infrared flux method (IRFM), as is the case for the unconstrained temperatures. Secondly, we find that the spectroscopic surface gravity can easily be corrected to a more accurate value using a linear function with the effective temperature. Tables 1 and 2 are available in electronic form at http://www.aanda.org

The application of color display techniques for the analysis of Nimbus infrared radiation data

NASA Technical Reports Server (NTRS)

Allison, L. J.; Cherrix, G. T.; Ausfresser, H.

1972-01-01

A color enhancement system designed for the Applications Technology Satellite (ATS) spin scan experiment has been adapted for the analysis of Nimbus infrared radiation measurements. For a given scene recorded on magnetic tape by the Nimbus scanning radiometers, a virtually unlimited number of color images can be produced at the ATS Operations Control Center from a color selector paper tape input. Linear image interpolation has produced radiation analyses in which each brightness-color interval has a smooth boundary without any mosaic effects. An annotated latitude-longitude gridding program makes it possible to precisely locate geophysical parameters, which permits accurate interpretation of pertinent meteorological, geological, hydrological, and oceanographic features.

Skeletal status and soft tissue composition in astronauts. Tissue and fluid changes by radionuclide absorptiometry in vivo

NASA Technical Reports Server (NTRS)

Cameron, J. R.; Mazess, R. B.; Wilson, C. R.

1973-01-01

A device has been constructed and tested which provides immediate readout of bone mineral content and bone width from absorptiometric scans with low energy radionuclides. The basis of this analog system is a logarithmic converter-integrator coupled with a precision linear ratemeter. The system provided accurate and reliable results on standards and ashed bone sections. Clinical measurements were made on about 100 patients with the direct readout system, and these were highly correlated with the results from digital scan data on the same patients. The direct readout system has been used successfully in field studies and surveys as well as for clinical observations.

Oblique scattering from radially inhomogeneous dielectric cylinders: An exact Volterra integral equation formulation

NASA Astrophysics Data System (ADS)

Tsalamengas, John L.

2018-07-01

We study plane-wave electromagnetic scattering by radially and strongly inhomogeneous dielectric cylinders at oblique incidence. The method of analysis relies on an exact reformulation of the underlying field equations as a first-order 4 × 4 system of differential equations and on the ability to restate the associated initial-value problem in the form of a system of coupled linear Volterra integral equations of the second kind. The integral equations so derived are discretized via a sophisticated variant of the Nyström method. The proposed method yields results accurate up to machine precision without relying on approximations. Numerical results and case studies ably demonstrate the efficiency and high accuracy of the algorithms.

Determination of thicknesses and temperatures of crystalline silicon wafers from optical measurements in the far infrared region

NASA Astrophysics Data System (ADS)

Franta, Daniel; Franta, Pavel; Vohánka, Jiří; Čermák, Martin; Ohlídal, Ivan

2018-05-01

Optical measurements of transmittance in the far infrared region performed on crystalline silicon wafers exhibit partially coherent interference effects appropriate for the determination of thicknesses of the wafers. The knowledge of accurate spectral and temperature dependencies of the optical constants of crystalline silicon in this spectral region is crucial for the determination of its thickness and vice versa. The recently published temperature dependent dispersion model of crystalline silicon is suitable for this purpose. Because the linear thermal expansion of crystalline silicon is known, the temperatures of the wafers can be determined with high precision from the evolution of the interference patterns at elevated temperatures.

Development and Validation of a Simultaneous RP-HPLCUV/DAD Method for Determination of Polyphenols in Gels Containing S. terebinthifolius Raddi (Anacardiaceae)

PubMed Central

Carvalho, Melina G.; Aragão, Cícero F. S; Raffin, Fernanda N.; de L. Moura, Túlio F. A.

2017-01-01

Topical gels containing extracts of Schinus terebinthifolius have been used to treat bacterial vaginosis. It has been reported that this species has antimicrobial, anti-inflammatory and anti-ulcerogenic properties, which can be attributed to the presence of phenolic compounds. In this work, a sensitive and selective reversed-phase HPLC-UV/DAD method for the simultaneous assay of six polyphenols that could be present in S. terebinthifolius was developed. The method was shown to be accurate and precise. Peak purity and similarity index both exceeded 0.99. Calibration curves were linear over the concentration range studied, with correlation coefficients between 0.9931 and 0.9974. This method was used to determine the polyphenol content of a hydroalcoholic extract and pharmacy-compounded vaginal gel. Although the method is useful to assess the 6 phenolic compounds, some compounds could not be detected in the products. SUMMARY A sensitive, selective, accurate and precise reversed-phase HPLC-UV/DAD method for the simultaneous assay of six polyphenols in S. terebinthifolius Raddi Abbreviations used: RP-HPLC-UV/DAD: Reverse Phase High Performance Liquid Chromatograph with Ultraviolet and Diode Array Detector, HPLC: High Performance Liquid Chromatograph, HPLC-UV: High Performance Liquid Chromatograph with Ultraviolet Detector, ANVISA: Brazilian National Health Surveillance Agency, LOD: Limit of detection, LOQ: Limit of quantitation PMID:28539726

Simultaneous Estimation of Ofloxacin, Clotrimazole, and Lignocaine Hydrochloride in Their Combined Ear-Drop Formulation by Two Spectrophotometric Methods.

PubMed

Bodiwala, Kunjan; Shah, Shailesh; Patel, Yogini; Prajapati, Pintu; Marolia, Bhavin; Kalyankar, Gajanan

2017-01-01

Two sensitive, accurate, and precise spectrophotometric methods have been developed and validated for the simultaneous estimation of ofloxacin (OFX), clotrimazole (CLZ), and lignocaine hydrochloride (LGN) in their combined dosage form (ear drops) without prior separation. The derivative ratio spectra method (method 1) includes the measurement of OFX and CLZ at zero-crossing points (ZCPs) of each other obtained from the ratio derivative spectra using standard LGN as a divisor, whereas the measurement of LGN at the ZCP of CLZ is obtained from the ratio derivative spectra using standard OFX as a divisor. The double divisor-ratio derivative method (method 2) includes the measurement of each drug at its amplitude in the double divisor-ratio spectra obtained using a standard mixture of the other two drugs as the divisor. Both methods were found to be linear (correlation coefficients of >0.996) over the ranges of 3-15, 10-50, and 20-100 μg/mL for OFX, CLZ, and LGN, respectively; precise (RSD of <2%); and accurate (recovery of >98%) for the estimation of each drug. The developed methods were successfully applied for the estimation of these drugs in a marketed ear-drop formulation. Excipients and other ingredients did not interfere with the estimation of these drugs. Both methods were statistically compared using the t-test.

Simultaneous multielement atomic absorption spectrometry with graphite furnace atomization

NASA Astrophysics Data System (ADS)

Harnly, James M.; Miller-Ihli, Nancy J.; O'Haver, Thomas C.

The extended analytical range capability of a simultaneous multielement atomic absorption continuum source spectrometer (SIMAAC) was tested for furnace atomization with respect to the signal measurement mode (peak height and area), the atomization mode (from the wall or from a platform), and the temperature program mode (stepped or ramped atomization). These parameters were evaluated with respect to the shapes of the analytical curves, the detection limits, carry-over contamination and accuracy. Peak area measurements gave more linear calibration curves. Methods for slowing the atomization step heating rate, the use of a ramped temperature program or a platform, produced similar calibration curves and longer linear ranges than atomization with a stepped temperature program. Peak height detection limits were best using stepped atomization from the wall. Peak area detection limits for all atomization modes were similar. Carry-over contamination was worse for peak area than peak height, worse for ramped atomization than stepped atomization, and worse for atomization from a platform than from the wall. Accurate determinations (100 ± 12% for Ca, Cu, Fe, Mn, and Zn in National Bureau of Standards' Standard Reference Materials Bovine Liver 1577 and Rice Flour 1568 were obtained using peak area measurements with ramped atomization from the wall and stepped atomization from a platform. Only stepped atomization from a platform gave accurate recoveries for K. Accurate recoveries, 100 ± 10%, with precisions ranging from 1 to 36 % (standard deviation), were obtained for the determination of Al, Co, Cr, Fe, Mn, Mo, Ni. Pb, V and Zn in Acidified Waters (NBS SRM 1643 and 1643a) using stepped atomization from a platform.

Fabrication of an infrared Shack-Hartmann sensor by combining high-speed single-point diamond milling and precision compression molding processes.

PubMed

Zhang, Lin; Zhou, Wenchen; Naples, Neil J; Yi, Allen Y

2018-05-01

A novel fabrication method by combining high-speed single-point diamond milling and precision compression molding processes for fabrication of discontinuous freeform microlens arrays was proposed. Compared with slow tool servo diamond broaching, high-speed single-point diamond milling was selected for its flexibility in the fabrication of true 3D optical surfaces with discontinuous features. The advantage of single-point diamond milling is that the surface features can be constructed sequentially by spacing the axes of a virtual spindle at arbitrary positions based on the combination of rotational and translational motions of both the high-speed spindle and linear slides. By employing this method, each micro-lenslet was regarded as a microstructure cell by passing the axis of the virtual spindle through the vertex of each cell. An optimization arithmetic based on minimum-area fabrication was introduced to the machining process to further increase the machining efficiency. After the mold insert was machined, it was employed to replicate the microlens array onto chalcogenide glass. In the ensuing optical measurement, the self-built Shack-Hartmann wavefront sensor was proven to be accurate in detecting an infrared wavefront by both experiments and numerical simulation. The combined results showed that precision compression molding of chalcogenide glasses could be an economic and precision optical fabrication technology for high-volume production of infrared optics.

Robust post-stall perching with a simple fixed-wing glider using LQR-Trees.

PubMed

Moore, Joseph; Cory, Rick; Tedrake, Russ

2014-06-01

Birds routinely execute post-stall maneuvers with a speed and precision far beyond the capabilities of our best aircraft control systems. One remarkable example is a bird exploiting post-stall pressure drag in order to rapidly decelerate to land on a perch. Stall is typically associated with a loss of control authority, and it is tempting to attribute this agility of birds to the intricate morphology of the wings and tail, to their precision sensing apparatus, or their ability to perform thrust vectoring. Here we ask whether an extremely simple fixed-wing glider (no propeller) with only a single actuator in the tail is capable of landing precisely on a perch from a large range of initial conditions. To answer this question, we focus on the design of the flight control system; building upon previous work which used linear feedback control design based on quadratic regulators (LQR), we develop nonlinear feedback control based on nonlinear model-predictive control and 'LQR-Trees'. Through simulation using a flat-plate model of the glider, we find that both nonlinear methods are capable of achieving an accurate bird-like perching maneuver from a large range of initial conditions; the 'LQR-Trees' algorithm is particularly useful due to its low computational burden at runtime and its inherent performance guarantees. With this in mind, we then implement the 'LQR-Trees' algorithm on real hardware and demonstrate a 95 percent perching success rate over 147 flights for a wide range of initial speeds. These results suggest that, at least in the absence of significant disturbances like wind gusts, complex wing morphology and sensing are not strictly required to achieve accurate and robust perching even in the post-stall flow regime.

Rapid and high-precision measurement of sulfur isotope and sulfur concentration in sediment pore water by multi-collector inductively coupled plasma mass spectrometry.

PubMed

Bian, Xiao-Peng; Yang, Tao; Lin, An-Jun; Jiang, Shao-Yong

2015-01-01

We have developed a technique for the rapid, precise and accurate determination of sulfur isotopes (δ(34)S) by MC-ICP-MS applicable to a range of sulfur-bearing solutions of different sulfur content. The 10 ppm Alfa-S solution (ammonium sulfate solution, working standard of the lab of the authors) was used to bracket other Alfa-S solutions of different concentrations and the measured δ(34)SV-CDT values of Alfa-S solutions deviate from the reference value to varying degrees (concentration effect). The stability of concentration effect has been verified and a correction curve has been constructed based on Alfa-S solutions to correct measured δ(34)SV-CDT values. The curve has been applied to AS solutions (dissolved ammonium sulfate from the lab of the authors) and pore water samples successfully, validating the reliability of our analytical method. This method also enables us to measure the sulfur concentration simultaneously when analyzing the sulfur isotope composition. There is a strong linear correlation (R(2)>0.999) between the sulfur concentrations and the intensity ratios of samples and the standard. We have constructed a regression curve based on Alfa-S solutions and this curve has been successfully used to determine sulfur concentrations of AS solutions and pore water samples. The analytical technique presented here enable rapid, precise and accurate S isotope measurement for a wide range of sulfur-bearing solutions - in particular for pore water samples with complex matrix and varying sulfur concentrations. Also, simultaneous measurement of sulfur concentrations is available. Copyright © 2014 Elsevier B.V. All rights reserved.

Development and validation of high-performance liquid chromatography and high-performance thin-layer chromatography methods for the quantification of khellin in Ammi visnaga seed

PubMed Central

Kamal, Abid; Khan, Washim; Ahmad, Sayeed; Ahmad, F. J.; Saleem, Kishwar

2015-01-01

Objective: The present study was used to design simple, accurate and sensitive reversed phase-high-performance liquid chromatography RP-HPLC and high-performance thin-layer chromatography (HPTLC) methods for the development of quantification of khellin present in the seeds of Ammi visnaga. Materials and Methods: RP-HPLC analysis was performed on a C18 column with methanol: Water (75: 25, v/v) as a mobile phase. The HPTLC method involved densitometric evaluation of khellin after resolving it on silica gel plate using ethyl acetate: Toluene: Formic acid (5.5:4.0:0.5, v/v/v) as a mobile phase. Results: The developed HPLC and HPTLC methods were validated for precision (interday, intraday and intersystem), robustness and accuracy, limit of detection and limit of quantification. The relationship between the concentration of standard solutions and the peak response was linear in both HPLC and HPTLC methods with the concentration range of 10–80 μg/mL in HPLC and 25–1,000 ng/spot in HPTLC for khellin. The % relative standard deviation values for method precision was found to be 0.63–1.97%, 0.62–2.05% in HPLC and HPTLC for khellin respectively. Accuracy of the method was checked by recovery studies conducted at three different concentration levels and the average percentage recovery was found to be 100.53% in HPLC and 100.08% in HPTLC for khellin. Conclusions: The developed HPLC and HPTLC methods for the quantification of khellin were found simple, precise, specific, sensitive and accurate which can be used for routine analysis and quality control of A. visnaga and several formulations containing it as an ingredient. PMID:26681890

Noncontact viscoelastic measurement of polymer thin films in a liquid medium using a long-needle AFM

NASA Astrophysics Data System (ADS)

Guan, Dongshi; Barraud, Chloe; Charlaix, Elisabeth; Tong, Penger

We report noncontact measurement of the viscoelastic property of polymer thin films in a liquid medium using frequency-modulation atomic force microscopy (FM-AFM) with a newly developed long-needle probe. The probe contains a long vertical glass fiber with one end adhered to a cantilever beam and the other end with a sharp tip placed near the liquid-film interface. The nanoscale flow generated by the resonant oscillation of the needle tip provides a precise hydrodynamic force acting on the soft surface of the thin film. By accurately measuring the mechanical response of the thin film, we obtain the elastic and loss moduli of the thin film using the linear response theory of elasto-hydrodynamics. The experiment verifies the theory and demonstrates its applications. The technique can be used to accurately measure the viscoelastic property of soft surfaces, such as those made of polymers, nano-bubbles, live cells and tissues. This work was supported by the Research Grants Council of Hong Kong SAR.

Quantification of urinary zwitterionic organic acids using weak-anion exchange chromatography with tandem MS detection.

PubMed

Bishop, Michael Jason; Crow, Brian S; Kovalcik, Kasey D; George, Joe; Bralley, James A

2007-04-01

A rapid and accurate quantitative method was developed and validated for the analysis of four urinary organic acids with nitrogen containing functional groups, formiminoglutamic acid (FIGLU), pyroglutamic acid (PYRGLU), 5-hydroxyindoleacetic acid (5-HIAA), and 2-methylhippuric acid (2-METHIP) by liquid chromatography tandem mass spectrometry (LC/MS/MS). The chromatography was developed using a weak anion-exchange amino column that provided mixed-mode retention of the analytes. The elution gradient relied on changes in mobile phase pH over a concave gradient, without the use of counter-ions or concentrated salt buffers. A simple sample preparation was used, only requiring the dilution of urine prior to instrumental analysis. The method was validated based on linearity (r2>or=0.995), accuracy (85-115%), precision (C.V.<12%), sample preparation stability (

3D multiscale crack propagation using the XFEM applied to a gas turbine blade

NASA Astrophysics Data System (ADS)

Holl, Matthias; Rogge, Timo; Loehnert, Stefan; Wriggers, Peter; Rolfes, Raimund

2014-01-01

This work presents a new multiscale technique to investigate advancing cracks in three dimensional space. This fully adaptive multiscale technique is designed to take into account cracks of different length scales efficiently, by enabling fine scale domains locally in regions of interest, i.e. where stress concentrations and high stress gradients occur. Due to crack propagation, these regions change during the simulation process. Cracks are modeled using the extended finite element method, such that an accurate and powerful numerical tool is achieved. Restricting ourselves to linear elastic fracture mechanics, the -integral yields an accurate solution of the stress intensity factors, and with the criterion of maximum hoop stress, a precise direction of growth. If necessary, the on the finest scale computed crack surface is finally transferred to the corresponding scale. In a final step, the model is applied to a quadrature point of a gas turbine blade, to compute crack growth on the microscale of a real structure.

Development of an automatic test equipment for nano gauging displacement transducers

NASA Astrophysics Data System (ADS)

Wang, Yung-Chen; Jywe, Wen-Yuh; Liu, Chien-Hung

2005-01-01

In order to satisfy the increasing demands on the precision in manufacturing technology, nanaometrology gradually becomes more important in manufacturing process. To ensure the precision of manufacture, precise measuring instruments and sensors play a decesive role for the accurate characterization and inspection of products. For linear length inspection, high precision gauging displacement transducers, i.e. nano gauging displacement transducers (NGDT), have been often utilized, which have been often utilized, which have the resolution in the nanometer range and can achieve an accuracy of less than 100 nm. Such measurement instruments include transducers based on electronic as well as optical measurement principles, e.g. inductive, incremental-optical or interference optical. To guarantee the accuracy and the traceability to the definition of the meter, calibration and test of NGDT are essential. Currently, there are some methods and machines for test of NGDT, but they suffer from various disadvantages. Some of them permit only manual test procedures which are time-consuming, e.g. with high accurate gauge blocks as material measures. Other tests can reach higher accuracy only in the micrometer range or result in uncertainties of more than 100 nm in the large measuring ranges. To realize the test of NGDT with a high resolution as well as a large measuring range, an automatic test equipment was constructed, that has a resolution of 1.24 nm, a measuring range of up to 20 nm (60 mm) and a measuring uncertainty of approximate ±10 nm can fulfil the requirements of high resolution within the nanometer range while simultaneously covering a large measuring range in the order of millimeters. The test system includes a stable frame, a polarization interferometer, an angle sensor, an angular control, a drive system and piezo translators. During the test procedure, the angular control and piezo translators minimize the Abbe error. For the automation of the test procedure a measuring program adhering to the measurement principle outlined in VDI/VDE 2617 guidelines was designed. With this program NGDT can be tested in less than thirty minutes with eleven measuring points and five repetitions. By mean of theoretical and experimental investigations it can be proved that the automatic test system achieves a test uncertainty of approx. ±10 nm at the measuring range of 18 mm, that corresponds to a relative uncertainty of approximately ±5 × 10-7. With small uncertainty, the minimization of the Abbe error and short test time, this system can be regarded as a universal and efficient precision test equipment, which is available for the accurate test of arbitrary high precision gauging displacement transducers.

Simultaneous determination three phytosterol compounds, campesterol, stigmasterol and daucosterol in Artemisia apiacea by high performance liquid chromatography-diode array ultraviolet/visible detector.

PubMed

Lee, Jiwoo; Weon, Jin Bae; Yun, Bo-Ra; Eom, Min Rye; Ma, Choong Je

2015-01-01

Artemisia apiacea is a traditional herbal medicine using treatment of eczema and jaundice in Eastern Asia, including China, Korea, and Japan. An accurate and sensitive analysis method using high performance liquid chromatography-diode array ultraviolet/visible detector and liquid chromatography-mass spectrometry for the simultaneous determination of three phytosterol compounds, campesterol, stigmasterol and daucosterol in A. apiacea was established. The analytes were separated on a Shiseido C18 column (5 μm, 4.6 mm I.D. ×250 mm) with gradient elution of 0.1% trifluoroacetic acid and acetonitrile. The flow rate was 1 mL/min and detection wavelengths were set at 205 and 254 nm. Validation of the method was performed to demonstrate its linearity, precision and accuracy. The calibration curves showed good linearity (R (2) > 0.9994). The limits of detection and limits of quantification were within the ranges 0.55-7.07 μg/mL and 1.67-21.44 μg/mL, respectively. And, the relative standard deviations of intra- and inter-day precision were <2.93%. The recoveries were found to be in the range of 90.03-104.91%. The developed method has been successfully applied to the analysis for quality control of campesterol, stigmasterol and daucosterol in A. apiacea.

Simultaneous determination three phytosterol compounds, campesterol, stigmasterol and daucosterol in Artemisia apiacea by high performance liquid chromatography-diode array ultraviolet/visible detector

PubMed Central

Lee, Jiwoo; Weon, Jin Bae; Yun, Bo-Ra; Eom, Min Rye; Ma, Choong Je

2015-01-01

Background: Artemisia apiacea is a traditional herbal medicine using treatment of eczema and jaundice in Eastern Asia, including China, Korea, and Japan. Objective: An accurate and sensitive analysis method using high performance liquid chromatography-diode array ultraviolet/visible detector and liquid chromatography–mass spectrometry for the simultaneous determination of three phytosterol compounds, campesterol, stigmasterol and daucosterol in A. apiacea was established. Materials and Methods: The analytes were separated on a Shiseido C18 column (5 μm, 4.6 mm I.D. ×250 mm) with gradient elution of 0.1% trifluoroacetic acid and acetonitrile. The flow rate was 1 mL/min and detection wavelengths were set at 205 and 254 nm. Results: Validation of the method was performed to demonstrate its linearity, precision and accuracy. The calibration curves showed good linearity (R2 > 0.9994). The limits of detection and limits of quantification were within the ranges 0.55–7.07 μg/mL and 1.67–21.44 μg/mL, respectively. And, the relative standard deviations of intra- and inter-day precision were <2.93%. The recoveries were found to be in the range of 90.03–104.91%. Conclusion: The developed method has been successfully applied to the analysis for quality control of campesterol, stigmasterol and daucosterol in A. apiacea. PMID:25829768

Electron kinetic effects on optical diagnostics in fusion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mirnov, V. V.; Den Hartog, D. J.; Duff, J.

At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP) and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. We calculate electron thermal corrections to the interferometric phase and polarization state of an EM wave propagating along tangential and poloidal chords (Faraday and Cotton-Mouton polarimetry) and perform analysis of the degree of polarization for incoherent TS. The precision of the previous lowest order linear in τ = T{sub e}/m{sub e}c{sup 2} model may be insufficient; we present a more precise model with τ{sup 2}-order corrections to satisfy themore » high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH and RF current drive effects. The classical problem of degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of T{sup e} measurement relevant to ITER operational scenarios.« less

Stress Degradation Studies on Varenicline Tartrate and Development of a Validated Stability-Indicating HPLC Method

PubMed Central

Pujeri, Sudhakar S.; Khader, Addagadde M. A.; Seetharamappa, Jaldappagari

2012-01-01

A simple, rapid and stability-indicating reversed-phase liquid chromatographic method was developed for the assay of varenicline tartrate (VRT) in the presence of its degradation products generated from forced decomposition studies. The HPLC separation was achieved on a C18 Inertsil column (250 mm × 4.6 mm i.d. particle size is 5 μm) employing a mobile phase consisting of ammonium acetate buffer containing trifluoroacetic acid (0.02M; pH 4) and acetonitrile in gradient program mode with a flow rate of 1.0 mL min−1. The UV detector was operated at 237 nm while column temperature was maintained at 40 °C. The developed method was validated as per ICH guidelines with respect to specificity, linearity, precision, accuracy, robustness and limit of quantification. The method was found to be simple, specific, precise and accurate. Selectivity of the proposed method was validated by subjecting the stock solution of VRT to acidic, basic, photolysis, oxidative and thermal degradation. The calibration curve was found to be linear in the concentration range of 0.1–192 μg mL−1 (R2 = 0.9994). The peaks of degradation products did not interfere with that of pure VRT. The utility of the developed method was examined by analyzing the tablets containing VRT. The results of analysis were subjected to statistical analysis. PMID:22396908

Mapping the genome of meta-generalized gradient approximation density functionals: The search for B97M-V

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mardirossian, Narbe; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720

2015-02-21

A meta-generalized gradient approximation density functional paired with the VV10 nonlocal correlation functional is presented. The functional form is selected from more than 10{sup 10} choices carved out of a functional space of almost 10{sup 40} possibilities. Raw data come from training a vast number of candidate functional forms on a comprehensive training set of 1095 data points and testing the resulting fits on a comprehensive primary test set of 1153 data points. Functional forms are ranked based on their ability to reproduce the data in both the training and primary test sets with minimum empiricism, and filtered based onmore » a set of physical constraints and an often-overlooked condition of satisfactory numerical precision with medium-sized integration grids. The resulting optimal functional form has 4 linear exchange parameters, 4 linear same-spin correlation parameters, and 4 linear opposite-spin correlation parameters, for a total of 12 fitted parameters. The final density functional, B97M-V, is further assessed on a secondary test set of 212 data points, applied to several large systems including the coronene dimer and water clusters, tested for the accurate prediction of intramolecular and intermolecular geometries, verified to have a readily attainable basis set limit, and checked for grid sensitivity. Compared to existing density functionals, B97M-V is remarkably accurate for non-bonded interactions and very satisfactory for thermochemical quantities such as atomization energies, but inherits the demonstrable limitations of existing local density functionals for barrier heights.« less

Cosmological constraints from the CFHTLenS shear measurements using a new, accurate, and flexible way of predicting non-linear mass clustering

NASA Astrophysics Data System (ADS)

Angulo, Raul E.; Hilbert, Stefan

2015-03-01

We explore the cosmological constraints from cosmic shear using a new way of modelling the non-linear matter correlation functions. The new formalism extends the method of Angulo & White, which manipulates outputs of N-body simulations to represent the 3D non-linear mass distribution in different cosmological scenarios. We show that predictions from our approach for shear two-point correlations at 1-300 arcmin separations are accurate at the ˜10 per cent level, even for extreme changes in cosmology. For moderate changes, with target cosmologies similar to that preferred by analyses of recent Planck data, the accuracy is close to ˜5 per cent. We combine this approach with a Monte Carlo Markov chain sampler to explore constraints on a Λ cold dark matter model from the shear correlation functions measured in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We obtain constraints on the parameter combination σ8(Ωm/0.27)0.6 = 0.801 ± 0.028. Combined with results from cosmic microwave background data, we obtain marginalized constraints on σ8 = 0.81 ± 0.01 and Ωm = 0.29 ± 0.01. These results are statistically compatible with previous analyses, which supports the validity of our approach. We discuss the advantages of our method and the potential it offers, including a path to model in detail (i) the effects of baryons, (ii) high-order shear correlation functions, and (iii) galaxy-galaxy lensing, among others, in future high-precision cosmological analyses.

Mapping the genome of meta-generalized gradient approximation density functionals: The search for B97M-V

DOE PAGES

Mardirossian, Narbe; Head-Gordon, Martin

2015-02-20

We present a meta-generalized gradient approximation density functional paired with the VV10 nonlocal correlation functional. The functional form is selected from more than 10 10 choices carved out of a functional space of almost 10 40 possibilities. This raw data comes from training a vast number of candidate functional forms on a comprehensive training set of 1095 data points and testing the resulting fits on a comprehensive primary test set of 1153 data points. Functional forms are ranked based on their ability to reproduce the data in both the training and primary test sets with minimum empiricism, and filteredmore » based on a set of physical constraints and an often-overlooked condition of satisfactory numerical precision with medium-sized integration grids. The resulting optimal functional form has 4 linear exchange parameters, 4 linear same-spin correlation parameters, and 4 linear opposite-spin correlation parameters, for a total of 12 fitted parameters. The final density functional, B97M-V, is further assessed on a secondary test set of 212 data points, applied to several large systems including the coronene dimer and water clusters, tested for the accurate prediction of intramolecular and intermolecular geometries, verified to have a readily attainable basis set limit, and checked for grid sensitivity. Compared to existing density functionals, B97M-V is remarkably accurate for non-bonded interactions and very satisfactory for thermochemical quantities such as atomization energies, but inherits the demonstrable limitations of existing local density functionals for barrier heights.« less

Accurate Solution of Multi-Region Continuum Biomolecule Electrostatic Problems Using the Linearized Poisson-Boltzmann Equation with Curved Boundary Elements

PubMed Central

Altman, Michael D.; Bardhan, Jaydeep P.; White, Jacob K.; Tidor, Bruce

2009-01-01

We present a boundary-element method (BEM) implementation for accurately solving problems in biomolecular electrostatics using the linearized Poisson–Boltzmann equation. Motivating this implementation is the desire to create a solver capable of precisely describing the geometries and topologies prevalent in continuum models of biological molecules. This implementation is enabled by the synthesis of four technologies developed or implemented specifically for this work. First, molecular and accessible surfaces used to describe dielectric and ion-exclusion boundaries were discretized with curved boundary elements that faithfully reproduce molecular geometries. Second, we avoided explicitly forming the dense BEM matrices and instead solved the linear systems with a preconditioned iterative method (GMRES), using a matrix compression algorithm (FFTSVD) to accelerate matrix-vector multiplication. Third, robust numerical integration methods were employed to accurately evaluate singular and near-singular integrals over the curved boundary elements. Finally, we present a general boundary-integral approach capable of modeling an arbitrary number of embedded homogeneous dielectric regions with differing dielectric constants, possible salt treatment, and point charges. A comparison of the presented BEM implementation and standard finite-difference techniques demonstrates that for certain classes of electrostatic calculations, such as determining absolute electrostatic solvation and rigid-binding free energies, the improved convergence properties of the BEM approach can have a significant impact on computed energetics. We also demonstrate that the improved accuracy offered by the curved-element BEM is important when more sophisticated techniques, such as non-rigid-binding models, are used to compute the relative electrostatic effects of molecular modifications. In addition, we show that electrostatic calculations requiring multiple solves using the same molecular geometry, such as charge optimization or component analysis, can be computed to high accuracy using the presented BEM approach, in compute times comparable to traditional finite-difference methods. PMID:18567005

Event-driven charge-coupled device design and applications therefor

NASA Technical Reports Server (NTRS)

Doty, John P. (Inventor); Ricker, Jr., George R. (Inventor); Burke, Barry E. (Inventor); Prigozhin, Gregory Y. (Inventor)

2005-01-01

An event-driven X-ray CCD imager device uses a floating-gate amplifier or other non-destructive readout device to non-destructively sense a charge level in a charge packet associated with a pixel. The output of the floating-gate amplifier is used to identify each pixel that has a charge level above a predetermined threshold. If the charge level is above a predetermined threshold the charge in the triggering charge packet and in the charge packets from neighboring pixels need to be measured accurately. A charge delay register is included in the event-driven X-ray CCD imager device to enable recovery of the charge packets from neighboring pixels for accurate measurement. When a charge packet reaches the end of the charge delay register, control logic either dumps the charge packet, or steers the charge packet to a charge FIFO to preserve it if the charge packet is determined to be a packet that needs accurate measurement. A floating-diffusion amplifier or other low-noise output stage device, which converts charge level to a voltage level with high precision, provides final measurement of the charge packets. The voltage level is eventually digitized by a high linearity ADC.

Combining simplicity with cost-effectiveness: Investigation of potential counterfeit of proton pump inhibitors through simulated formulations using thin-layer chromatography.

PubMed

Bhatt, Nejal M; Chavada, Vijay D; Sanyal, Mallika; Shrivastav, Pranav S

2016-11-18

A simple, accurate and precise high-performance thin-layer chromatographic method has been developed and validated for the analysis of proton pump inhibitors (PPIs) and their co-formulated drugs, available as binary combination. Planar chromatographic separation was achieved using a single mobile phase comprising of toluene: iso-propranol: acetone: ammonia 5.0:2.3:2.5:0.2 (v/v/v/v) for the analysis of 14 analytes on aluminium-backed layer of silica gel 60 FG 254 . Densitometric determination of the separated spots was done at 290nm. The method was validated according to ICH guidelines for linearity, precision and accuracy, sensitivity, specificity and robustness. The method showed good linear response for the selected drugs as indicated by the high values of correlation coefficients (≥0.9993). The limit of detection and limit of quantiation were in the range of 6.9-159.2ng/band and 20.8-478.1ng/band respectively for all the analytes. The optimized conditions afforded adequate resolution of each PPI from their co-formulated drugs and provided unambiguous identification of the co-formulated drugs from their homologous retardation factors (hR f ). The only limitation of the method was the inability to separate two PPIs, rabeprazole and lansoprazole from each other. Nevertheless, it is proposed that peak spectra recording and comparison with standard drug spot can be a viable option for assignment of TLC spots. The method performance was assessed by analyzing different laboratory simulated mixtures and some marketed formulations of the selected drugs. The developed method was successfully used to investigate potential counterfeit of PPIs through a series of simulated formulations with good accuracy and precision. Copyright © 2016 Elsevier B.V. All rights reserved.

Theoretically Guided Analytical Method Development and Validation for the Estimation of Rifampicin in a Mixture of Isoniazid and Pyrazinamide by UV Spectrophotometer

PubMed Central

Khan, Mohammad F.; Rita, Shamima A.; Kayser, Md. Shahidulla; Islam, Md. Shariful; Asad, Sharmeen; Bin Rashid, Ridwan; Bari, Md. Abdul; Rahman, Muhammed M.; Al Aman, D. A. Anwar; Setu, Nurul I.; Banoo, Rebecca; Rashid, Mohammad A.

2017-01-01

A simple, rapid, economic, accurate, and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0–8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λmax of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5–35.0 μg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 to 1.70% and 1.63 to 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 μg/mL, respectively. In addition, the developed method was successfully applied to determine rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh. PMID:28503547

Theoretically Guided Analytical Method Development and Validation for the Estimation of Rifampicin in a Mixture of Isoniazid and Pyrazinamide by UV Spectrophotometer.

PubMed

Khan, Mohammad F; Rita, Shamima A; Kayser, Md Shahidulla; Islam, Md Shariful; Asad, Sharmeen; Bin Rashid, Ridwan; Bari, Md Abdul; Rahman, Muhammed M; Al Aman, D A Anwar; Setu, Nurul I; Banoo, Rebecca; Rashid, Mohammad A

2017-01-01

A simple, rapid, economic, accurate, and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0-8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λ max of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5-35.0 μg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 to 1.70% and 1.63 to 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 μg/mL, respectively. In addition, the developed method was successfully applied to determine rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh.

The vanishing limit of the square-well fluid: The adhesive hard-sphere model as a reference system

NASA Astrophysics Data System (ADS)

Largo, J.; Miller, M. A.; Sciortino, F.

2008-04-01

We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width δ as small as 0.005 times the particle diameter σ. For small δ, the reduced second virial coefficient at the critical point B2*c is found to depend linearly on δ. The observed weak linear dependence is not sufficient to produce any significant observable effect if the critical temperature Tc is estimated via a constant B2*c assumption, due to the highly nonlinear transformation between B2*c and Tc. This explains the previously observed validity of the law of corresponding states. The critical density ρc is also found to be constant when measured in units of the cube of the average distance between two bonded particles (1+0.5δ)σ. The possibility of describing the δ →0 dependence with precise functional forms provides improved accurate estimates of the critical parameters of the adhesive hard-sphere model.

The vanishing limit of the square-well fluid: the adhesive hard-sphere model as a reference system.

PubMed

Largo, J; Miller, M A; Sciortino, F

2008-04-07

We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width delta as small as 0.005 times the particle diameter sigma. For small delta, the reduced second virial coefficient at the critical point B2*c is found to depend linearly on delta. The observed weak linear dependence is not sufficient to produce any significant observable effect if the critical temperature Tc is estimated via a constant B2*c assumption, due to the highly nonlinear transformation between B2*c and Tc. This explains the previously observed validity of the law of corresponding states. The critical density rho c is also found to be constant when measured in units of the cube of the average distance between two bonded particles (1+0.5 delta)sigma. The possibility of describing the delta-->0 dependence with precise functional forms provides improved accurate estimates of the critical parameters of the adhesive hard-sphere model.

The large-scale three-point correlation function of the SDSS BOSS DR12 CMASS galaxies

NASA Astrophysics Data System (ADS)

Slepian, Zachary; Eisenstein, Daniel J.; Beutler, Florian; Chuang, Chia-Hsun; Cuesta, Antonio J.; Ge, Jian; Gil-Marín, Héctor; Ho, Shirley; Kitaura, Francisco-Shu; McBride, Cameron K.; Nichol, Robert C.; Percival, Will J.; Rodríguez-Torres, Sergio; Ross, Ashley J.; Scoccimarro, Román; Seo, Hee-Jong; Tinker, Jeremy; Tojeiro, Rita; Vargas-Magaña, Mariana

2017-06-01

We report a measurement of the large-scale three-point correlation function of galaxies using the largest data set for this purpose to date, 777 202 luminous red galaxies in the Sloan Digital Sky Survey Baryon Acoustic Oscillation Spectroscopic Survey (SDSS BOSS) DR12 CMASS sample. This work exploits the novel algorithm of Slepian & Eisenstein to compute the multipole moments of the 3PCF in O(N^2) time, with N the number of galaxies. Leading-order perturbation theory models the data well in a compressed basis where one triangle side is integrated out. We also present an accurate and computationally efficient means of estimating the covariance matrix. With these techniques, the redshift-space linear and non-linear bias are measured, with 2.6 per cent precision on the former if σ8 is fixed. The data also indicate a 2.8σ preference for the BAO, confirming the presence of BAO in the three-point function.

CT artifact recognition for the nuclear technologist.

PubMed

Popilock, Robert; Sandrasagaren, Kumar; Harris, Lowell; Kaser, Keith A

2008-06-01

The goal of this article is to make the PET/CT and SPECT/CT operator aware of common artifacts found in CT. In diagnostic imaging, the ability to render an accurate diagnosis requires the technologist to take steps to optimize image quality and recognize when image quality has been compromised-that is, when there is an image artifact. One way these artifacts occur is through the inability of the CT linear attenuation image to precisely represent the linear attenuation map of a 2-dimensional section through the body. The reasons for this inability are multifold. First, CT is subject to the laws of x-ray quantum physics resulting in noise in all CT images. Moreover, all current CT x-ray systems generate a spectrum of energies. Also, CT scanners use detectors of finite dimension, as are the x-ray focal spots; reconstruct images from a finite number of samples distributed over a finite number of views; and acquire the data for each reconstruction over a finite period.

Application of stochastic particle swarm optimization algorithm to determine the graded refractive index distribution in participating media

NASA Astrophysics Data System (ADS)

Wei, Lin-Yang; Qi, Hong; Ren, Ya-Tao; Ruan, Li-Ming

2016-11-01

Inverse estimation of the refractive index distribution in one-dimensional participating media with graded refractive index (GRI) is investigated. The forward radiative transfer problem is solved by the Chebyshev collocation spectral method. The stochastic particle swarm optimization (SPSO) algorithm is employed to retrieve three kinds of GRI distribution, i.e. the linear, sinusoidal and quadratic GRI distribution. The retrieval accuracy of GRI distribution with different wall emissivity, optical thickness, absorption coefficients and scattering coefficients are discussed thoroughly. To improve the retrieval accuracy of quadratic GRI distribution, a double-layer model is proposed to supply more measurement information. The influence of measurement errors upon the precision of estimated results is also investigated. Considering the GRI distribution is unknown beforehand in practice, a quadratic function is employed to retrieve the linear GRI by SPSO algorithm. All the results show that the SPSO algorithm is applicable to retrieve different GRI distributions in participating media accurately even with noisy data.

Development and validation of RP-UHPLC procedure for estimation of 5-amino salicyclic acid in 5-amino salicyclic acid rectal suppositories

NASA Astrophysics Data System (ADS)

Balaji, Jayagopal; Shivashankar, Murugesh

2017-11-01

The present study describes a simple and robust reverse phase ultra performance liquid chromatography (RP-UPLC) method for the quantification of 5-amino salicyclic acid in 5-amino salicyclic acid rectal capsules. Successful separation of Mesalamine peak from excipient peaks and diluent were achieved on a Acquity C8 (50 × 2.1 mm, 1.7 μm) and UV detector at 254 nm, 0.3 mL/min as a flow rate, and 3 μL as an injection volume. For the RP-UPLC method, phosphate buffer and methanol was used as mobile phases at ratio of 83:17 and the column temperature was 25 °C. Percentage recovery obtained in the range of 98.7 - 99.7 % and the method is linear for Mesalamine for specified concentration range with coefficient of variation (r) not less than 0.99. The proposed RP-UPLC method was found to be specific, linear, precise, accurate and robust.

[Extracting THz absorption coefficient spectrum based on accurate determination of sample thickness].

PubMed

Li, Zhi; Zhang, Zhao-hui; Zhao, Xiao-yan; Su, Hai-xia; Yan, Fang

2012-04-01

Extracting absorption spectrum in THz band is one of the important aspects in THz applications. Sample's absorption coefficient has a complex nonlinear relationship with its thickness. However, as it is not convenient to measure the thickness directly, absorption spectrum is usually determined incorrectly. Based on the method proposed by Duvillaret which was used to precisely determine the thickness of LiNbO3, the approach to measuring the absorption coefficient spectra of glutamine and histidine in frequency range from 0.3 to 2.6 THz(1 THz = 10(12) Hz) was improved in this paper. In order to validate the correctness of this absorption spectrum, we designed a series of experiments to compare the linearity of absorption coefficient belonging to one kind amino acid in different concentrations. The results indicate that as agreed by Lambert-Beer's Law, absorption coefficient spectrum of amino acid from the improved algorithm performs better linearity with its concentration than that from the common algorithm, which can be the basis of quantitative analysis in further researches.

The Precise Repositioning Instrument for Genioplasty and a Three-Dimensional Printing Technique for Treatment of Complex Facial Asymmetry.

PubMed

Wang, Lin; Tian, Dan; Sun, Xiumei; Xiao, Yanju; Chen, Li; Wu, Guomin

2017-08-01

Facial asymmetry is very common in maxillofacial deformities. It is difficult to achieve accurate reconstruction. With the help of 3D printing models and surgical templates, the osteotomy line and the amount of bone grinding can be accurate. Also, by means of the precise repositioning instrument, the repositioning of genioplasty can be accurate and quick. In this study, we present a three-dimensional printing technique and the precise repositioning instrument to guide the osteotomy and repositioning, and illustrate their feasibility and validity. Eight patients with complex facial asymmetries were studied. A precise 3D printing model was obtained. We made the preoperative design and surgical templates according to it. The surgical templates and precise repositioning instrument were used to obtain an accurate osteotomy and repositioning during the operation. Postoperative measurements were made based on computed tomographic data, including chin point deviation as well as the symmetry of the mandible evaluated by 3D curve functions. All patients obtained satisfactory esthetic results, and no recurrences occurred during follow-up. The results showed that we achieved clinically acceptable precision for the mandible and chin. The mean and SD of ICC between R-Post and L-Post were 0.973 ± 0.007. The mean and SD of chin point deviation 6 months after the operation were 0.63 ± 0.19 mm. The results of this study suggest that the three-dimensional printing technique and the precise repositioning instrument could aid in making better operation designs and more accurate manipulation in orthognathic surgery for complex facial asymmetry. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Towards accurate cosmological predictions for rapidly oscillating scalar fields as dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ureña-López, L. Arturo; Gonzalez-Morales, Alma X., E-mail: lurena@ugto.mx, E-mail: alma.gonzalez@fisica.ugto.mx

2016-07-01

As we are entering the era of precision cosmology, it is necessary to count on accurate cosmological predictions from any proposed model of dark matter. In this paper we present a novel approach to the cosmological evolution of scalar fields that eases their analytic and numerical analysis at the background and at the linear order of perturbations. The new method makes use of appropriate angular variables that simplify the writing of the equations of motion, and which also show that the usual field variables play a secondary role in the cosmological dynamics. We apply the method to a scalar fieldmore » endowed with a quadratic potential and revisit its properties as dark matter. Some of the results known in the literature are recovered, and a better understanding of the physical properties of the model is provided. It is confirmed that there exists a Jeans wavenumber k {sub J} , directly related to the suppression of linear perturbations at wavenumbers k > k {sub J} , and which is verified to be k {sub J} = a √ mH . We also discuss some semi-analytical results that are well satisfied by the full numerical solutions obtained from an amended version of the CMB code CLASS. Finally we draw some of the implications that this new treatment of the equations of motion may have in the prediction of cosmological observables from scalar field dark matter models.« less

Light scattering by ultrasonically-controlled small particles: system design, calibration, and measurement results

NASA Astrophysics Data System (ADS)

Kassamakov, Ivan; Maconi, Göran; Penttilä, Antti; Helander, Petteri; Gritsevich, Maria; Puranen, Tuomas; Salmi, Ari; Hæggström, Edward; Muinonen, Karri

2018-02-01

We present the design of a novel scatterometer for precise measurement of the angular Mueller matrix profile of a mm- to µm-sized sample held in place by sound. The scatterometer comprises a tunable multimode Argon-krypton laser (with possibility to set 1 of the 12 wavelengths in visible range), linear polarizers, a reference photomultiplier tube (PMT) for monitoring the beam intensity, and a micro-PMT module mounted radially towards the sample at an adjustable radius. The measurement angle is controlled by a motor-driven rotation stage with an accuracy of 15'. The system is fully automated using LabVIEW, including the FPGA-based data acquisition and the instrument's user interface. The calibration protocol ensures accurate measurements by using a control sphere sample (diameter 3 mm, refractive index of 1.5) fixed first on a static holder followed by accurate multi-wavelength measurements of the same sample levitated ultrasonically. To demonstrate performance of the scatterometer, we conducted detailed measurements of light scattered by a particle derived from the Chelyabinsk meteorite, as well as planetary analogue materials. The measurements are the first of this kind, since they are obtained using controlled spectral angular scattering including linear polarization effects, for arbitrary shaped objects. Thus, our novel approach permits a non-destructive, disturbance-free measurement with control of the orientation and location of the scattering object.

Analytical framework for reconstructing heterogeneous environmental variables from mammal community structure.

PubMed

Louys, Julien; Meloro, Carlo; Elton, Sarah; Ditchfield, Peter; Bishop, Laura C

2015-01-01

We test the performance of two models that use mammalian communities to reconstruct multivariate palaeoenvironments. While both models exploit the correlation between mammal communities (defined in terms of functional groups) and arboreal heterogeneity, the first uses a multiple multivariate regression of community structure and arboreal heterogeneity, while the second uses a linear regression of the principal components of each ecospace. The success of these methods means the palaeoenvironment of a particular locality can be reconstructed in terms of the proportions of heavy, moderate, light, and absent tree canopy cover. The linear regression is less biased, and more precisely and accurately reconstructs heavy tree canopy cover than the multiple multivariate model. However, the multiple multivariate model performs better than the linear regression for all other canopy cover categories. Both models consistently perform better than randomly generated reconstructions. We apply both models to the palaeocommunity of the Upper Laetolil Beds, Tanzania. Our reconstructions indicate that there was very little heavy tree cover at this site (likely less than 10%), with the palaeo-landscape instead comprising a mixture of light and absent tree cover. These reconstructions help resolve the previous conflicting palaeoecological reconstructions made for this site. Copyright © 2014 Elsevier Ltd. All rights reserved.

Visual Tracking via Sparse and Local Linear Coding.

PubMed

Wang, Guofeng; Qin, Xueying; Zhong, Fan; Liu, Yue; Li, Hongbo; Peng, Qunsheng; Yang, Ming-Hsuan

2015-11-01

The state search is an important component of any object tracking algorithm. Numerous algorithms have been proposed, but stochastic sampling methods (e.g., particle filters) are arguably one of the most effective approaches. However, the discretization of the state space complicates the search for the precise object location. In this paper, we propose a novel tracking algorithm that extends the state space of particle observations from discrete to continuous. The solution is determined accurately via iterative linear coding between two convex hulls. The algorithm is modeled by an optimal function, which can be efficiently solved by either convex sparse coding or locality constrained linear coding. The algorithm is also very flexible and can be combined with many generic object representations. Thus, we first use sparse representation to achieve an efficient searching mechanism of the algorithm and demonstrate its accuracy. Next, two other object representation models, i.e., least soft-threshold squares and adaptive structural local sparse appearance, are implemented with improved accuracy to demonstrate the flexibility of our algorithm. Qualitative and quantitative experimental results demonstrate that the proposed tracking algorithm performs favorably against the state-of-the-art methods in dynamic scenes.

Evaluation of empirical rule of linearly correlated peptide selection (ERLPS) for proteotypic peptide-based quantitative proteomics.

PubMed

Liu, Kehui; Zhang, Jiyang; Fu, Bin; Xie, Hongwei; Wang, Yingchun; Qian, Xiaohong

2014-07-01

Precise protein quantification is essential in comparative proteomics. Currently, quantification bias is inevitable when using proteotypic peptide-based quantitative proteomics strategy for the differences in peptides measurability. To improve quantification accuracy, we proposed an "empirical rule for linearly correlated peptide selection (ERLPS)" in quantitative proteomics in our previous work. However, a systematic evaluation on general application of ERLPS in quantitative proteomics under diverse experimental conditions needs to be conducted. In this study, the practice workflow of ERLPS was explicitly illustrated; different experimental variables, such as, different MS systems, sample complexities, sample preparations, elution gradients, matrix effects, loading amounts, and other factors were comprehensively investigated to evaluate the applicability, reproducibility, and transferability of ERPLS. The results demonstrated that ERLPS was highly reproducible and transferable within appropriate loading amounts and linearly correlated response peptides should be selected for each specific experiment. ERLPS was used to proteome samples from yeast to mouse and human, and in quantitative methods from label-free to O18/O16-labeled and SILAC analysis, and enabled accurate measurements for all proteotypic peptide-based quantitative proteomics over a large dynamic range. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pre-treatment patient-specific stopping power by combining list-mode proton radiography and x-ray CT

NASA Astrophysics Data System (ADS)

Collins-Fekete, Charles-Antoine; Brousmiche, Sébastien; Hansen, David C.; Beaulieu, Luc; Seco, Joao

2017-09-01

The relative stopping power (RSP) uncertainty is the largest contributor to the range uncertainty in proton therapy. The purpose of this work was to develop a systematic method that yields accurate and patient-specific RSPs by combining (1) pre-treatment x-ray CT and (2) daily proton radiography of the patient. The method was formulated as a penalized least squares optimization problem (argmin(\\Vert {A}{x}-{b}\\Vert _22 )). The parameter A represents the cumulative path-length crossed by the proton in each material, separated by thresholding on the HU. The material RSPs (water equivalent thickness/physical thickness) are denoted by x. The parameter b is the list-mode proton radiography produced using Geant4 simulations. The problem was solved using a non-negative linear-solver with {x}≥slant0 . A was computed by superposing proton trajectories calculated with a cubic or linear spline approach to the CT. The material’s RSP assigned in Geant4 were used for reference while the clinical HU-RSP calibration curve was used for comparison. The Gammex RMI-467 phantom was first investigated. The standard deviation between the estimated material RSP and the calculated RSP is 0.45%. The robustness of the techniques was then assessed as a function of the number of projections and initial proton energy. Optimization with two initial projections yields precise RSP (⩽1.0%) for 330 MeV protons. 250 MeV protons have shown higher uncertainty (⩽2.0%) due to the loss of precision in the path estimate. Anthropomorphic phantoms of the head, pelvis, and lung were subsequently evaluated. Accurate RSP has been obtained for the head (μ =0.21+/-1.63% ), the lung (μ=0.06+/-0.99% ) and the pelvis (μ=0.90+/-3.87% ). The range precision has been optimized using the calibration curves obtained with the algorithm, yielding a mean R80 difference to the reference of 0.11  ±0.09%, 0.28  ±  0.34% and 0.05 +/- 0.06% in the same order. The solution’s accuracy is limited by the assumed HU/RSP bijection, neglecting inherent degeneracy. The proposed formulation of the problem with prior knowledge x-ray CT demonstrates potential to increase the accuracy of present RSP estimates.

Pre-treatment patient-specific stopping power by combining list-mode proton radiography and x-ray CT.

PubMed

Collins-Fekete, Charles-Antoine; Brousmiche, Sébastien; Hansen, David C; Beaulieu, Luc; Seco, Joao

2017-08-03

The relative stopping power (RSP) uncertainty is the largest contributor to the range uncertainty in proton therapy. The purpose of this work was to develop a systematic method that yields accurate and patient-specific RSPs by combining (1) pre-treatment x-ray CT and (2) daily proton radiography of the patient. The method was formulated as a penalized least squares optimization problem (argmin([Formula: see text])). The parameter A represents the cumulative path-length crossed by the proton in each material, separated by thresholding on the HU. The material RSPs (water equivalent thickness/physical thickness) are denoted by x. The parameter b is the list-mode proton radiography produced using Geant4 simulations. The problem was solved using a non-negative linear-solver with [Formula: see text]. A was computed by superposing proton trajectories calculated with a cubic or linear spline approach to the CT. The material's RSP assigned in Geant4 were used for reference while the clinical HU-RSP calibration curve was used for comparison. The Gammex RMI-467 phantom was first investigated. The standard deviation between the estimated material RSP and the calculated RSP is 0.45%. The robustness of the techniques was then assessed as a function of the number of projections and initial proton energy. Optimization with two initial projections yields precise RSP (⩽1.0%) for 330 MeV protons. 250 MeV protons have shown higher uncertainty (⩽2.0%) due to the loss of precision in the path estimate. Anthropomorphic phantoms of the head, pelvis, and lung were subsequently evaluated. Accurate RSP has been obtained for the head ([Formula: see text]), the lung ([Formula: see text]) and the pelvis ([Formula: see text]). The range precision has been optimized using the calibration curves obtained with the algorithm, yielding a mean [Formula: see text] difference to the reference of 0.11  ±0.09%, 0.28  ±  0.34% and [Formula: see text] in the same order. The solution's accuracy is limited by the assumed HU/RSP bijection, neglecting inherent degeneracy. The proposed formulation of the problem with prior knowledge x-ray CT demonstrates potential to increase the accuracy of present RSP estimates.

Simultaneous determination of gatifloxacin and ambroxol hydrochloride from tablet dosage form using reversed-phase high performance liquid chromatography.

PubMed

Shahed, Mirza; Nanda, Rabindra; Dehghan, Muhammad Hassan; Nasreen, Huda; Feroz, Shaikh

2008-05-01

A reversed-phase high performance liquid chromatography (HPLC) method was developed, validated, and used for the quantitative determination of gatifloxacin (GA) and ambroxol hydrochloride (AM), from its tablet dosage form. Chromatographic separation was performed on a HiQ Sil C18 column (250 mm x 4.6 mm, 5 microm), with a mobile phase comprising of a mixture of 0.01 mol/L potassium dihydrogen orthophosphate buffer and acetonitrile (70 : 30, v/v), and pH adjusted to 3 with orthophosphoric acid, at a flow rate of 1 mL/min, with detection at 247 nm. Separation was completed in less than 10 min. As per International Conference on Harmonisation (ICH) guidelines the method was validated for linearity, accuracy, precision, limit of quantitation, limit of detection, and robustness. Linearity of GA was found to be in the range of 10 -60 microg/mL and that for AM was found to be 5 - 30 microg/mL. The correlation coefficients were 0.999 6 and 0.999 3 for GA and AM respectively. The results of the tablet analysis (n = 5) were found to be 99.94% with +/- 0.25% standard deviation (SD) and 99.98% with +/- 0.36% SD for GA and AM respectively. Percent recovery of GA was found to be 99.92% - 100.02% and that of AM was 99.86% - 100.16%. The assay experiment shows that the method is free from interference of excipients. This demonstrates that the developed HPLC method is simple, linear, precise, and accurate, and can be conveniently adopted for the routine quality control analysis of the tablet.

A versatile program for the calculation of linear accelerator room shielding.

PubMed

Hassan, Zeinab El-Taher; Farag, Nehad M; Elshemey, Wael M

2018-03-22

This work aims at designing a computer program to calculate the necessary amount of shielding for a given or proposed linear accelerator room design in radiotherapy. The program (Shield Calculation in Radiotherapy, SCR) has been developed using Microsoft Visual Basic. It applies the treatment room shielding calculations of NCRP report no. 151 to calculate proper shielding thicknesses for a given linear accelerator treatment room design. The program is composed of six main user-friendly interfaces. The first enables the user to upload their choice of treatment room design and to measure the distances required for shielding calculations. The second interface enables the user to calculate the primary barrier thickness in case of three-dimensional conventional radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and total body irradiation (TBI). The third interface calculates the required secondary barrier thickness due to both scattered and leakage radiation. The fourth and fifth interfaces provide a means to calculate the photon dose equivalent for low and high energy radiation, respectively, in door and maze areas. The sixth interface enables the user to calculate the skyshine radiation for photons and neutrons. The SCR program has been successfully validated, precisely reproducing all of the calculated examples presented in NCRP report no. 151 in a simple and fast manner. Moreover, it easily performed the same calculations for a test design that was also calculated manually, and produced the same results. The program includes a new and important feature that is the ability to calculate required treatment room thickness in case of IMRT and TBI. It is characterised by simplicity, precision, data saving, printing and retrieval, in addition to providing a means for uploading and testing any proposed treatment room shielding design. The SCR program provides comprehensive, simple, fast and accurate room shielding calculations in radiotherapy.

Radiographic evaluation of BFX acetabular component position in dogs.

PubMed

Renwick, Alasdair; Gemmill, Toby; Pink, Jonathan; Brodbelt, David; McKee, Malcolm

2011-07-01

To assess the reliability of radiographic measurement of angle of lateral opening (ALO) and angle of version of BFX acetabular cups. In vitro radiographic study. BFX cups (24, 28, and 32 mm). Total hip replacement constructs (cups, 17 mm femoral head and a #7 CFX stem) were mounted on an inclinometer. Ventrodorsal radiographs were obtained with ALO varying between 21° and 70° and inclination set at 0°, 10°, 20°, and 30°. Radiographs were randomized using a random sequence generator. Three observers blinded to the radiograph order assessed ALO using 3 methods: (1) an ellipse method based on trigonometry; (2) using a measurement from the center of the femoral head to the truncated surface of the cup; (3) by visual estimation using a reference chart. Version was measured by assessing the ventral edge of the truncated surface. ALO methods 2 and 3 were accurate and precise to within 10° and were significantly more accurate and precise than method 1 (P < .001). All methods were significantly less accurate with increasing inclination. Version measurement was accurate and precise to within 7° with 0-20° of inclination, but significantly less accurate with 30° of inclination. Methods 2 and 3, but not method 1, were sufficiently accurate and precise to be clinically useful. Version measurement was clinically useful when inclination was ≤ 20°. © Copyright 2011 by The American College of Veterinary Surgeons.

Fluid transport properties by equilibrium molecular dynamics. I. Methodology at extreme fluid states

NASA Astrophysics Data System (ADS)

Dysthe, D. K.; Fuchs, A. H.; Rousseau, B.

1999-02-01

The Green-Kubo formalism for evaluating transport coefficients by molecular dynamics has been applied to flexible, multicenter models of linear and branched alkanes in the gas phase and in the liquid phase from ambient conditions to close to the triple point. The effects of integration time step, potential cutoff and system size have been studied and shown to be small compared to the computational precision except for diffusion in gaseous n-butane. The RATTLE algorithm is shown to give accurate transport coefficients for time steps up to a limit of 8 fs. The different relaxation mechanisms in the fluids have been studied and it is shown that the longest relaxation time of the system governs the statistical precision of the results. By measuring the longest relaxation time of a system one can obtain a reliable error estimate from a single trajectory. The accuracy of the Green-Kubo method is shown to be as good as the precision for all states and models used in this study even when the system relaxation time becomes very long. The efficiency of the method is shown to be comparable to nonequilibrium methods. The transport coefficients for two recently proposed potential models are presented, showing deviations from experiment of 0%-66%.

Automated landmark extraction for orthodontic measurement of faces using the 3-camera photogrammetry methodology.

PubMed

Deli, Roberto; Di Gioia, Eliana; Galantucci, Luigi Maria; Percoco, Gianluca

2010-01-01

To set up a three-dimensional photogrammetric scanning system for precise landmark measurements, without any physical contact, using a low-cost and noninvasive digital photogrammetric solution, for supporting several necessity in clinical orthodontics and/or surgery diagnosis. Thirty coded targets were directly applied onto the subject's face on the soft tissue landmarks, and then, 3 simultaneous photos were acquired using photogrammetry, at room light conditions. For comparison, a dummy head was digitized both with a photogrammetric technique and with the laser scanner Minolta Vivid 910i (Konica Minolta, Tokyo, Japan). The precise measurement of the landmarks is ranged between 0.017 and 0.029 mm. The system automatically measures spatial position of face landmarks, from which distances and angles can be obtained. The facial measurements were compared with those done using laser scanning and manual caliper. The adopted method gives higher precision than the others (0.022-mm mean value on points and 0.038-mm mean value on linear distances on a dummy head), is simple, and can be used easily as a standard routine. The study demonstrated the validity of photogrammetry for accurate digitization of human face landmarks. This research points out the potential of this low-cost photogrammetry approach for medical digitization.

Rigorous high-precision enclosures of fixed points and their invariant manifolds

NASA Astrophysics Data System (ADS)

Wittig, Alexander N.

The well established concept of Taylor Models is introduced, which offer highly accurate C0 enclosures of functional dependencies, combining high-order polynomial approximation of functions and rigorous estimates of the truncation error, performed using verified arithmetic. The focus of this work is on the application of Taylor Models in algorithms for strongly non-linear dynamical systems. A method is proposed to extend the existing implementation of Taylor Models in COSY INFINITY from double precision coefficients to arbitrary precision coefficients. Great care is taken to maintain the highest efficiency possible by adaptively adjusting the precision of higher order coefficients in the polynomial expansion. High precision operations are based on clever combinations of elementary floating point operations yielding exact values for round-off errors. An experimental high precision interval data type is developed and implemented. Algorithms for the verified computation of intrinsic functions based on the High Precision Interval datatype are developed and described in detail. The application of these operations in the implementation of High Precision Taylor Models is discussed. An application of Taylor Model methods to the verification of fixed points is presented by verifying the existence of a period 15 fixed point in a near standard Henon map. Verification is performed using different verified methods such as double precision Taylor Models, High Precision intervals and High Precision Taylor Models. Results and performance of each method are compared. An automated rigorous fixed point finder is implemented, allowing the fully automated search for all fixed points of a function within a given domain. It returns a list of verified enclosures of each fixed point, optionally verifying uniqueness within these enclosures. An application of the fixed point finder to the rigorous analysis of beam transfer maps in accelerator physics is presented. Previous work done by Johannes Grote is extended to compute very accurate polynomial approximations to invariant manifolds of discrete maps of arbitrary dimension around hyperbolic fixed points. The algorithm presented allows for automatic removal of resonances occurring during construction. A method for the rigorous enclosure of invariant manifolds of continuous systems is introduced. Using methods developed for discrete maps, polynomial approximations of invariant manifolds of hyperbolic fixed points of ODEs are obtained. These approximations are outfit with a sharp error bound which is verified to rigorously contain the manifolds. While we focus on the three dimensional case, verification in higher dimensions is possible using similar techniques. Integrating the resulting enclosures using the verified COSY VI integrator, the initial manifold enclosures are expanded to yield sharp enclosures of large parts of the stable and unstable manifolds. To demonstrate the effectiveness of this method, we construct enclosures of the invariant manifolds of the Lorenz system and show pictures of the resulting manifold enclosures. To the best of our knowledge, these enclosures are the largest verified enclosures of manifolds in the Lorenz system in existence.

Quantitative Analysis of Clopidogrel Bisulphate and Aspirin by First Derivative Spectrophotometric Method in Tablets

PubMed Central

Game, Madhuri D.; Gabhane, K. B.; Sakarkar, D. M.

2010-01-01

A simple, accurate and precise spectrophotometric method has been developed for simultaneous estimation of clopidogrel bisulphate and aspirin by employing first order derivative zero crossing method. The first order derivative absorption at 232.5 nm (zero cross point of aspirin) was used for clopidogrel bisulphate and 211.3 nm (zero cross point of clopidogrel bisulphate) for aspirin.Both the drugs obeyed linearity in the concentration range of 5.0 μg/ml to 25.0 μg/ml (correlation coefficient r2<1). No interference was found between both determined constituents and those of matrix. The method was validated statistically and recovery studies were carried out to confirm the accuracy of the method. PMID:21969765

Kramers-Kronig relations in Laser Intensity Modulation Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuncer, Enis

2006-01-01

In this short paper, the Kramers-Kronig relations for the Laser Intensity Modulation Method (LIMM) are presented to check the self-consistency of experimentally obtained complex current densities. The numerical procedure yields well defined, precise estimates for the real and the imaginary parts of the LIMM current density calculated from its imaginary and real parts, respectively. The procedure also determines an accurate high frequency real current value which appears to be an intrinsic material parameter similar to that of the dielectric permittivity at optical frequencies. Note that the problem considered here couples two different material properties, thermal and electrical, consequently the validitymore » of the Kramers-Kronig relation indicates that the problem is invariant and linear.« less

Quantitative determination of a chemically modified hammerhead ribozyme in blood plasma using 96-well solid-phase extraction coupled with high-performance liquid chromatography or capillary gel electrophoresis.

PubMed

Bellon, L; Maloney, L; Zinnen, S P; Sandberg, J A; Johnson, K E

2000-08-01

Versatile bioanalytical assays to detect chemically stabilized hammerhead ribozyme and putative ribozyme metabolites from plasma are described. The extraction protocols presented are based on serial solid-phase extractions performed on a 96-well plate format and are compatible with either IEX-HPLC or CGE back-end analysis. A validation of both assays confirmed that both the HPLC and the CGE methods possess the required linearity, accuracy, and precision to accurately measure concentrations of hammerhead ribozyme extracted from plasma. These methods should be of general use to detect and quantitate ribozymes from other biological fluids such as serum and urine. Copyright 2000 Academic Press.

Relativistic all-order many-body calculation of energies, wavelengths, and M 1 and E 2 transition rates for the 3 dn configurations in tungsten ions

NASA Astrophysics Data System (ADS)

Safronova, M. S.; Safronova, U. I.; Porsev, S. G.; Kozlov, M. G.; Ralchenko, Yu.

2018-01-01

Energy levels, wavelengths, magnetic-dipole and electric-quadrupole transition rates between the low-lying states are evaluated for W51 + to W54 + ions with 3 dn (n =2 to 5) electronic configurations by using an approach combining configuration interaction with the linearized coupled-cluster single-double method. The QED corrections are directly incorporated into the calculations and their effect is studied in detail. Uncertainties of the calculations are discussed. This study of such highly charged ions with the present method opens the way for future applications allowing an accurate prediction of properties for a very wide range of highly charged ions aimed at providing precision benchmarks for various applications.

Thermodynamic functions, freezing transition, and phase diagram of dense carbon-oxygen mixtures in white dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iyetomi, H.; Ogata, S.; Ichimaru, S.

1989-07-01

Equations of state for dense carbon-oxygen (C-O) binary-ionic mixtures (BIM's) appropriate to the interiors of white dwarfs are investigated through Monte Carlo simulations, by solution of relevant integral equations andvariational calculations in the density-functional formalism. It is thereby shown that the internal energies of the C-O BIM solids and fluids both obey precisely the linear mixing formulas. We then present an accurate calculation of the phase diagram associated with freezing transitions in such BIM materials, resulting in a novel prediction of an azeotropic diagram. Discontinuities of the mass density across the azeotropic phase boundaries areevaluated numerically for application to amore » study of white-dwarf evolution.« less

Using Precision in STEM Language: A Qualitative Look

ERIC Educational Resources Information Center

Capraro, Mary M.; Bicer, Ali; Grant, Melva R.; Lincoln, Yvonna S.

2017-01-01

Teachers need to develop a variety of pedagogical strategies that can encourage precise and accurate communication--an extremely important 21st century skill. Precision with STEM oral language is essential. Emphasizing oral communication with precise language in combination with increased spatial skills with modeling can improve the chances of…

Automatic Organ Segmentation for CT Scans Based on Super-Pixel and Convolutional Neural Networks.

PubMed

Liu, Xiaoming; Guo, Shuxu; Yang, Bingtao; Ma, Shuzhi; Zhang, Huimao; Li, Jing; Sun, Changjian; Jin, Lanyi; Li, Xueyan; Yang, Qi; Fu, Yu

2018-04-20

Accurate segmentation of specific organ from computed tomography (CT) scans is a basic and crucial task for accurate diagnosis and treatment. To avoid time-consuming manual optimization and to help physicians distinguish diseases, an automatic organ segmentation framework is presented. The framework utilized convolution neural networks (CNN) to classify pixels. To reduce the redundant inputs, the simple linear iterative clustering (SLIC) of super-pixels and the support vector machine (SVM) classifier are introduced. To establish the perfect boundary of organs in one-pixel-level, the pixels need to be classified step-by-step. First, the SLIC is used to cut an image into grids and extract respective digital signatures. Next, the signature is classified by the SVM, and the rough edges are acquired. Finally, a precise boundary is obtained by the CNN, which is based on patches around each pixel-point. The framework is applied to abdominal CT scans of livers and high-resolution computed tomography (HRCT) scans of lungs. The experimental CT scans are derived from two public datasets (Sliver 07 and a Chinese local dataset). Experimental results show that the proposed method can precisely and efficiently detect the organs. This method consumes 38 s/slice for liver segmentation. The Dice coefficient of the liver segmentation results reaches to 97.43%. For lung segmentation, the Dice coefficient is 97.93%. This finding demonstrates that the proposed framework is a favorable method for lung segmentation of HRCT scans.

DETERMINING MOTOR INERTIA OF A STRESS-CONTROLLED RHEOMETER.

PubMed

Klemuk, Sarah A; Titze, Ingo R

2009-01-01

Viscoelastic measurements made with a stress-controlled rheometer are affected by system inertia. Of all contributors to system inertia, motor inertia is the largest. Its value is usually determined empirically and precision is rarely if ever specified. Inertia uncertainty has negligible effects on rheologic measurements below the coupled motor/plate/sample resonant frequency. But above the resonant frequency, G' values of soft viscoelastic materials such as dispersions, gels, biomaterials, and non-Newtonian polymers, err quadratically due to inertia uncertainty. In the present investigation, valid rheologic measurements were achieved near and above the coupled resonant frequency for a non-Newtonian reference material. At these elevated frequencies, accuracy in motor inertia is critical. Here we compare two methods for determining motor-inertia accurately. For the first (commercially-used) phase method, frequency responses of standard fluids were measured. Phase between G' and G" was analyzed at 5-70 Hz for motor inertia values of 50-150% of the manufacturer's nominal value. For a newly-devised two-plate method (10 mm and 60 mm parallel plates), dynamic measurements of a non-Newtonian standard were collected. Using a linear equation of motion with inertia, viscosity, and elasticity coefficients, G' expressions for both plates were equated and motor inertia was determined to be accurate (by comparison to the phase method) with a precision of ± 3%. The newly developed two-plate method had advantages of expressly eliminating dependence on gap, was explicitly derived from basic principles, quantified the error, and required fewer experiments than the commercially used phase method.

Simultaneous estimation of four proton pump inhibitors--lansoprazole, omeprazole, pantoprazole and rabeprazole: development of a novel generic HPLC-UV method and its application to clinical pharmacokinetic study.

PubMed

Bharathi, D Vijaya; Hotha, Kishore Kumar; Jagadeesh, B; Chatki, Pankaj K; Thriveni, K; Mullangi, Ramesh; Naidu, A

2009-07-01

A highly selective, sensitive and accurate HPLC method has been developed and validated for the estimation of four proton-pump inhibitors (PPI), lansoprazole (LPZ), omeprazole (OPZ), pantoprazole (PPZ) and rabeprazole (RPZ), with 500 microL human plasma using zonisamide as an internal standard (IS). The sample preparation involved simple liquid-liquid extraction of LPZ, OPZ, PPZ and RPZ and IS from human plasma with ethyl acetate. The baseline separation of all the peaks was achieved with 0.1% triethylamine (pH 6.0):acetonitrile (72:28, v/v) at a flow rate of 1 mL/min on a Zorbax C(8) column. The total chromatographic run time was 11.0 min and the simultaneous elution of IS, OPZ, RPZ, PPZ and LPZ occurred at approximately 2.42, 4.45, 5.02 and 9.37 min, respectively. The method was proved to be accurate and precise at linearity range of 20.61-1999.79 ng/mL with a correlation coefficient (r) of >or=0.999. The limit of quantitation for each of the PPI studied was 20.61 ng/mL. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers. (c) 2009 John Wiley & Sons, Ltd.

Quantitative analysis of benzodiazepines in vitreous humor by high-performance liquid chromatography

PubMed Central

Bazmi, Elham; Behnoush, Behnam; Akhgari, Maryam; Bahmanabadi, Leila

2016-01-01

Objective: Benzodiazepines are frequently screened drugs in emergency toxicology, drugs of abuse testing, and in forensic cases. As the variations of benzodiazepines concentrations in biological samples during bleeding, postmortem changes, and redistribution could be biasing forensic medicine examinations, hence selecting a suitable sample and a validated accurate method is essential for the quantitative analysis of these main drug categories. The aim of this study was to develop a valid method for the determination of four benzodiazepines (flurazepam, lorazepam, alprazolam, and diazepam) in vitreous humor using liquid–liquid extraction and high-performance liquid chromatography. Methods: Sample preparation was carried out using liquid–liquid extraction with n-hexane: ethyl acetate and subsequent detection by high-performance liquid chromatography method coupled to diode array detector. This method was applied to quantify benzodiazepines in 21 authentic vitreous humor samples. Linear curve for each drug was obtained within the range of 30–3000 ng/mL with coefficient of correlation higher than 0.99. Results: The limit of detection and quantitation were 30 and 100 ng/mL respectively for four drugs. The method showed an appropriate intra- and inter-day precision (coefficient of variation < 10%). Benzodiazepines recoveries were estimated to be over 80%. The method showed high selectivity; no additional peak due to interfering substances in samples was observed. Conclusion: The present method was selective, sensitive, accurate, and precise for the quantitative analysis of benzodiazepines in vitreous humor samples in forensic toxicology laboratory. PMID:27635251

Using hyperspectral data in precision farming applications

USDA-ARS?s Scientific Manuscript database

Precision farming practices such as variable rate applications of fertilizer and agricultural chemicals require accurate field variability mapping. This chapter investigated the value of hyperspectral remote sensing in providing useful information for five applications of precision farming: (a) Soil...

Validation of HPLC and UV spectrophotometric methods for the determination of meropenem in pharmaceutical dosage form.

PubMed

Mendez, Andreas S L; Steppe, Martin; Schapoval, Elfrides E S

2003-12-04

A high-performance liquid chromatographic method and a UV spectrophotometric method for the quantitative determination of meropenem, a highly active carbapenem antibiotic, in powder for injection were developed in present work. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. Chromatography was carried out by reversed-phase technique on an RP-18 column with a mobile phase composed of 30 mM monobasic phosphate buffer and acetonitrile (90:10; v/v), adjusted to pH 3.0 with orthophosphoric acid. The UV spectrophotometric method was performed at 298 nm. The samples were prepared in water and the stability of meropenem in aqueous solution at 4 and 25 degrees C was studied. The results were satisfactory with good stability after 24 h at 4 degrees C. Statistical analysis by Student's t-test showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and can be used for the reliable quantitation of meropenem in pharmaceutical dosage form.

Development and validation of liquid chromatographic and UV derivative spectrophotometric methods for the determination of famciclovir in pharmaceutical dosage forms.

PubMed

Srinubabu, Gedela; Sudharani, Batchu; Sridhar, Lade; Rao, Jvln Seshagiri

2006-06-01

A high-performance liquid chromatographic method and a UV derivative spectrophotometric method for the determination of famciclovir, a highly active antiviral agent, in tablets were developed in the present work. The various parameters, such as linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. HPLC was carried out by using the reversed-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic phosphate buffer and methanol (50 : 50; v/v), adjusted to pH 3.05 with orthophosphoric acid. The mobile phase was pumped at a flow rate of 1 ml/min and detection was made at 242 nm with UV dual absorbance detector. The first derivative UV spectrophotometric method was performed at 226.5 nm. Statistical analysis was done by Student's t-test and F-test, which showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and therefore can be used for its Intended purpose.

Optimization and Validation of a Sensitive Method for HPLC-PDA Simultaneous Determination of Torasemide and Spironolactone in Human Plasma using Central Composite Design.

PubMed

Subramanian, Venkatesan; Nagappan, Kannappan; Sandeep Mannemala, Sai

2015-01-01

A sensitive, accurate, precise and rapid HPLC-PDA method was developed and validated for the simultaneous determination of torasemide and spironolactone in human plasma using Design of experiments. Central composite design was used to optimize the method using content of acetonitrile, concentration of buffer and pH of mobile phase as independent variables, while the retention factor of spironolactone, resolution between torasemide and phenobarbitone; and retention time of phenobarbitone were chosen as dependent variables. The chromatographic separation was achieved on Phenomenex C(18) column and the mobile phase comprising 20 mM potassium dihydrogen ortho phosphate buffer (pH-3.2) and acetonitrile in 82.5:17.5 v/v pumped at a flow rate of 1.0 mL min(-1). The method was validated according to USFDA guidelines in terms of selectivity, linearity, accuracy, precision, recovery and stability. The limit of quantitation values were 80 and 50 ng mL(-1) for torasemide and spironolactone respectively. Furthermore, the sensitivity and simplicity of the method suggests the validity of method for routine clinical studies.

Analysis of Mycosporine-Like Amino Acids in Selected Algae and Cyanobacteria by Hydrophilic Interaction Liquid Chromatography and a Novel MAA from the Red Alga Catenella repens

PubMed Central

Hartmann, Anja; Becker, Kathrin; Karsten, Ulf; Remias, Daniel; Ganzera, Markus

2015-01-01

Mycosporine-like amino acids (MAAs), a group of small secondary metabolites found in algae, cyanobacteria, lichens and fungi, have become ecologically and pharmacologically relevant because of their pronounced UV-absorbing and photo-protective potential. Their analytical characterization is generally achieved by reversed phase HPLC and the compounds are often quantified based on molar extinction coefficients. As an alternative approach, in our study a fully validated hydrophilic interaction liquid chromatography (HILIC) method is presented. It enables the precise quantification of several analytes with adequate retention times in a single run, and can be coupled directly to MS. Excellent linear correlation coefficients (R2 > 0.9991) were obtained, with limit of detection (LOD) values ranging from 0.16 to 0.43 µg/mL. Furthermore, the assay was found to be accurate (recovery rates from 89.8% to 104.1%) and precise (intra-day precision: 5.6%, inter-day precision ≤6.6%). Several algae were assayed for their content of known MAAs like porphyra-334, shinorine, and palythine. Liquid chromatography-mass spectrometry (LC-MS) data indicated a novel compound in some of them, which could be isolated from the marine species Catenella repens and structurally elucidated by nuclear magnetic resonance spectroscopy (NMR) as (E)-3-hydroxy-2-((5-hydroxy-5-(hydroxymethyl)-2-methoxy-3-((2-sulfoethyl)amino)cyclohex-2-en-1-ylidene)amino) propanoic acid, a novel MAA called catenelline. PMID:26473886

Analysis of Mycosporine-Like Amino Acids in Selected Algae and Cyanobacteria by Hydrophilic Interaction Liquid Chromatography and a Novel MAA from the Red Alga Catenella repens.

PubMed

Hartmann, Anja; Becker, Kathrin; Karsten, Ulf; Remias, Daniel; Ganzera, Markus

2015-10-09

Mycosporine-like amino acids (MAAs), a group of small secondary metabolites found in algae, cyanobacteria, lichens and fungi, have become ecologically and pharmacologically relevant because of their pronounced UV-absorbing and photo-protective potential. Their analytical characterization is generally achieved by reversed phase HPLC and the compounds are often quantified based on molar extinction coefficients. As an alternative approach, in our study a fully validated hydrophilic interaction liquid chromatography (HILIC) method is presented. It enables the precise quantification of several analytes with adequate retention times in a single run, and can be coupled directly to MS. Excellent linear correlation coefficients (R² > 0.9991) were obtained, with limit of detection (LOD) values ranging from 0.16 to 0.43 µg/mL. Furthermore, the assay was found to be accurate (recovery rates from 89.8% to 104.1%) and precise (intra-day precision: 5.6%, inter-day precision ≤6.6%). Several algae were assayed for their content of known MAAs like porphyra-334, shinorine, and palythine. Liquid chromatography-mass spectrometry (LC-MS) data indicated a novel compound in some of them, which could be isolated from the marine species Catenella repens and structurally elucidated by nuclear magnetic resonance spectroscopy (NMR) as (E)-3-hydroxy-2-((5-hydroxy-5-(hydroxymethyl)-2-methoxy-3-((2-sulfoethyl)amino)cyclohex-2-en-1-ylidene)amino) propanoic acid, a novel MAA called catenelline.

High-precision Ru isotopic measurements by multi-collector ICP-MS.

PubMed

Becker, Harry; Dalpe, Claude; Walker, Richard J

2002-06-01

Ruthenium isotopic data for a pure Aldrich ruthenium nitrate solution obtained using a Nu Plasma multi collector inductively coupled plasma-mass spectrometer (MC-ICP-MS) shows excellent agreement (better than 1 epsilon unit = 1 part in 10(4)) with data obtained by other techniques for the mass range between 96 and 101 amu. External precisions are at the 0.5-1.7 epsilon level (2sigma). Higher sensitivity for MC ICP-MS compared to negative thermal ionization mass spectrometry (N-TIMS) is offset by the uncertainties introduced by relatively large mass discrimination and instabilities in the plasma source-ion extraction region that affect the long-term reproducibility. Large mass bias correction in ICP mass spectrometry demands particular attention to be paid to the choice of normalizing isotopes. Because of its position in the mass spectrum and the large mass bias correction, obtaining precise and accurate abundance data for 104Ru by MC-ICP-MS remains difficult. Internal and external mass bias correction schemes in this mass range may show similar shortcomings if the isotope of interest does not lie within the mass range covered by the masses used for normalization. Analyses of meteorite samples show that if isobaric interferences from Mo are sufficiently large (Ru/Mo < 10(4)), uncertainties on the Mo interference correction propagate through the mass bias correction and yield inaccurate results for Ru isotopic compositions. Second-order linear corrections may be used to correct for these inaccuracies, but such results are generally less precise than N-TIMS data.

WE-F-16A-04: Micro-Irradiator Treatment Verification with High-Resolution 3D-Printed Rodent-Morphic Dosimeters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bache, S; Belley, M; Benning, R

2014-06-15

Purpose: Pre-clinical micro-radiation therapy studies often utilize very small beams (∼0.5-5mm), and require accurate dose delivery in order to effectively investigate treatment efficacy. Here we present a novel high-resolution absolute 3D dosimetry procedure, capable of ∼100-micron isotopic dosimetry in anatomically accurate rodent-morphic phantoms Methods: Anatomically accurate rat-shaped 3D dosimeters were made using 3D printing techniques from outer body contours and spinal contours outlined on CT. The dosimeters were made from a radiochromic plastic material PRESAGE, and incorporated high-Z PRESASGE inserts mimicking the spine. A simulated 180-degree spinal arc treatment was delivered through a 2 step process: (i) cone-beam-CT image-guided positioningmore » was performed to precisely position the rat-dosimeter for treatment on the XRad225 small animal irradiator, then (ii) treatment was delivered with a simulated spine-treatment with a 180-degree arc with 20mm x 10mm cone at 225 kVp. Dose distribution was determined from the optical density change using a high-resolution in-house optical-CT system. Absolute dosimetry was enabled through calibration against a novel nano-particle scintillation detector positioned in a channel in the center of the distribution. Results: Sufficient contrast between regular PRESAGE (tissue equivalent) and high-Z PRESAGE (spinal insert) was observed to enable highly accurate image-guided alignment and targeting. The PRESAGE was found to have linear optical density (OD) change sensitivity with respect to dose (R{sup 2} = 0.9993). Absolute dose for 360-second irradiation at isocenter was found to be 9.21Gy when measured with OD change, and 9.4Gy with nano-particle detector- an agreement within 2%. The 3D dose distribution was measured at 500-micron resolution Conclusion: This work demonstrates for the first time, the feasibility of accurate absolute 3D dose measurement in anatomically accurate rat phantoms containing variable density PRESAGE material (tissue equivalent and bone equivalent). This method enables precise treatment verification of micro-radiation therapies, and enhances the robustness of tumor radio-response studies. This work was supported by NIH R01CA100835.« less

Past and present cosmic structure in the SDSS DR7 main sample

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasche, J.; Leclercq, F.; Wandelt, B.D., E-mail: jasche@iap.fr, E-mail: florent.leclercq@polytechnique.org, E-mail: wandelt@iap.fr

2015-01-01

We present a chrono-cosmography project, aiming at the inference of the four dimensional formation history of the observed large scale structure from its origin to the present epoch. To do so, we perform a full-scale Bayesian analysis of the northern galactic cap of the Sloan Digital Sky Survey (SDSS) Data Release 7 main galaxy sample, relying on a fully probabilistic, physical model of the non-linearly evolved density field. Besides inferring initial conditions from observations, our methodology naturally and accurately reconstructs non-linear features at the present epoch, such as walls and filaments, corresponding to high-order correlation functions generated by late-time structuremore » formation. Our inference framework self-consistently accounts for typical observational systematic and statistical uncertainties such as noise, survey geometry and selection effects. We further account for luminosity dependent galaxy biases and automatic noise calibration within a fully Bayesian approach. As a result, this analysis provides highly-detailed and accurate reconstructions of the present density field on scales larger than ∼ 3 Mpc/h, constrained by SDSS observations. This approach also leads to the first quantitative inference of plausible formation histories of the dynamic large scale structure underlying the observed galaxy distribution. The results described in this work constitute the first full Bayesian non-linear analysis of the cosmic large scale structure with the demonstrated capability of uncertainty quantification. Some of these results will be made publicly available along with this work. The level of detail of inferred results and the high degree of control on observational uncertainties pave the path towards high precision chrono-cosmography, the subject of simultaneously studying the dynamics and the morphology of the inhomogeneous Universe.« less

Discovering Optimum Method to Extract Depth Information for Nearshore Coastal Waters from SENTINEL-2A - Case Study: Nayband Bay, Iran

NASA Astrophysics Data System (ADS)

Kabiri, K.

2017-09-01

The capabilities of Sentinel-2A imagery to determine bathymetric information in shallow coastal waters were examined. In this regard, two Sentinel-2A images (acquired on February and March 2016 in calm weather and relatively low turbidity) were selected from Nayband Bay, located in the northern Persian Gulf. In addition, a precise and accurate bathymetric map for the study area were obtained and used for both calibrating the models and validating the results. Traditional linear and ratio transform techniques, as well as a novel integrated method, were employed to determine depth values. All possible combinations of the three bands (Band 2: blue (458-523 nm), Band 3: green (543-578 nm), and Band 4: red (650-680 nm), spatial resolution: 10 m) have been considered (11 options) using the traditional linear and ratio transform techniques, together with 10 model options for the integrated method. The accuracy of each model was assessed by comparing the determined bathymetric information with field measured values. The correlation coefficients (R2), and root mean square errors (RMSE) for validation points were calculated for all models and for two satellite images. When compared with the linear transform method, the method employing ratio transformation with a combination of all three bands yielded more accurate results (R2Mac = 0.795, R2Feb = 0.777, RMSEMac = 1.889 m, and RMSEFeb =2.039 m). Although most of the integrated transform methods (specifically the method including all bands and band ratios) have yielded the highest accuracy, these increments were not significant, hence the ratio transformation has selected as optimum method.

Hydrogen atoms can be located accurately and precisely by x-ray crystallography.

PubMed

Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M; Woźniak, Krzysztof; Jayatilaka, Dylan

2016-05-01

Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A-H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A-H bond lengths with those from neutron measurements for A-H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors.

Hydrogen atoms can be located accurately and precisely by x-ray crystallography

PubMed Central

Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M.; Woźniak, Krzysztof; Jayatilaka, Dylan

2016-01-01

Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A–H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A–H bond lengths with those from neutron measurements for A–H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors. PMID:27386545

An ultraviolet-spectrophotometric method for the determination of glimepiride in solid dosage forms.

PubMed

Afieroho, Ozadheoghene E; Okorie, Ogbonna; Okonkwo, Tochukwu J N

2011-06-01

Considering the cost of acquiring a liquid chromatographic instrument in underdeveloped economies, the rising incidence of diabetes mellitus, the need to evaluate the quality performance of glimepiride generics, and the need for less toxic processes, this research is an imperative. The method was validated for linearity, recovery accuracy, intra- and inter-day precision, specificity in the presence of excipients, and inter-day stability under laboratory conditions. Student's t test at the 95% confidence limit was used for statistics. Using 96% ethanol as solvent, a less toxic and cost-effective spectrophotometric method for the determination of glimepiride in solid dosage forms was developed and validated. The results of the validated parameters showed a λ(max) of 231 nm, linearity range of 0.5-22 μg/mL, precision with relative SD of <1.0%, recovery accuracy of 100.8%, regression equation of y = 45.741x + 0.0202, R(2) = 0.999, limit of detection of 0.35 μg/mL, and negligible interference from common excipients and colorants. The method was found to be accurate at the 95% confidence limit compared with the standard liquid chromatographic method with comparable reproducibility when used to assay the formulated products Amaryl(®) (sanofi-aventis, Paris, France) and Mepyril(®) (May & Baker Nigeria PLC, Ikeja, Nigeria). The results obtained for the validated parameters were within allowable limits. This method is recommended for routine quality control analysis.

Simultaneous determination of four neuroprotective compounds of Tilia amurensis by high performance liquid chromatography coupled with diode array detector

PubMed Central

Lee, Bohyung; Weon, Jin Bae; Yun, Bo-Ra; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Background: Tilia amurensis consists of various compounds, such as flavonoids and terpenoids. Objective: A simple and reliable high performance liquid chromatography (HPLC) coupled with the diode array detector (DAD) method has been established for simultaneous determination of epicatechin, nudiposide, lyoniside, and scopoletin isolated from Tilia amurensis. Materials and Methods: Optimum separations were obtained with a SHISEIDO C18 column by gradient eluton, with 0.1% Trifluoroacetic acid (TFA) water-methanol as the mobile phase. The gradient elution system was completed within 40 minutes. The flow rate and detection wavelength were 1 mL/minute, 205 nm, 250 nm, and 280 nm, respectively. Results: Validation of the analytical method was evaluated by linearity, precision, and the accuracy test. The calibration curve was linear over the established range with R2 > 0.997. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01-15.20 μg/mL and 0.03-46.06 μg/mL. The method exhibited an intraday and interday precision range of 96.25-105.66% and 93.52-109.92%, respectively (RSD <2.80%). The recoveries and relative standard deviation (RSD) of the four compounds in Tilia amurensis were in the range of 90.42-104.84% and 0.2-2.58%. Conclusion: This developed method was accurate and reliable for the quality evaluation of the four compounds isolated from Tilia amurensis. PMID:25210303

Stability-indicating method for simultaneous estimation of olmesartan medoxomile, amlodipine besylate and hydrochlorothiazide by RP-HPLC in tablet dosage form.

PubMed

Jain, P S; Patel, M K; Gorle, A P; Chaudhari, A J; Surana, S J

2012-09-01

A simple, specific, accurate and precise stability-indicating reversed-phase high-performance liquid chromatographic method was developed for simultaneous estimation of olmesartan medoxomile (OLME), amlodipine besylate (AMLO) and hydrochlorothiazide (HCTZ) in tablet dosage form. The method was developed using an RP C18 base deactivated silica column (250 × 4.6 mm, 5 µm) with a mobile phase consisting of triethylamine (pH 3.0) adjusted with orthophosphoric acid (A) and acetonitrile (B), with a timed gradient program of T/%B: 0/30, 7/70, 8/30, 10/30 with a flow rate of 1.4 mL/min. Ultraviolet detection was used at 236 nm. The retention times for OLME, AMLO and HCTZ were found to be 6.72, 4.28 and 2.30, respectively. The proposed method was validated for precision, accuracy, linearity, range, robustness, ruggedness and force degradation study. The calibration curves of OLME, AMLO and HCTZ were linear over the range of 50-150, 12.5-37.5 and 31-93 µg/mL, respectively. The method was found to be sensitive. The limits of detection of OLME, AMLO and HCTZ were determined 0.19, 0.16 and 0.22 µg/mL and limits of quantification of OLME, AMLO and HCTZ were determined 0.57, 0.49 and 0.66, respectively. Forced degradation study was performed according to International Conference on Harmonization guidelines.

Development and validation of a rapid reverse-phase HPLC method for the determination of methotrexate from nanostructured liquid crystalline systems.

PubMed

Zuben, E S Von; Oliveira, A G; Chorilli, M; Scarpa, M V

2018-03-05

A reversed-phase liquid chromatography (RP-LC) method was successfully developed and validated for the determination of methotrexate in nanostructured liquid crystalline systems composed by polyether functional siloxane and silicone polyether copolymer. The LC method was performed on RP C18-ODS column, Agilent Zorbax® (4.6 x 250 mm, 5 μm), maintained at room temperature, with a mobile phase constituted by a mixture of 50 mM ammonium acetate buffer (pH 6.0) and methanol (77:23,v/v) with a flow rate of 1.0 mL/min, using ultraviolet detection at 313 nm. The parameters used in the validation process were linearity, specificity, intra and inter-day precision, accuracy, robustness. The quantitation and detection limits yielded good results. The calibration plot assumed linear behavior from 5.0-150.0 μg. mL-1 (r2 = 0.9999). The methotrexate was subjected to oxidation, acid, base and neutral degradation, photolysis and heat as stress conditions. There were no interfering peaks at or near the retention time of methotrexate. The nanostructured liquid crystalline systems did not interfere with the analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.20 %. The method developed proved to be simple, sensitive, accurate, precise, reproducible and therefore adequate for routine analysis of methotrexate in nanostructured liquid crystalline systems.

Development and validation of sensitive LC/MS/MS method for quantitative bioanalysis of levonorgestrel in rat plasma and application to pharmacokinetics study.

PubMed

Ananthula, Suryatheja; Janagam, Dileep R; Jamalapuram, Seshulatha; Johnson, James R; Mandrell, Timothy D; Lowe, Tao L

2015-10-15

Rapid, sensitive, selective and accurate LC/MS/MS method was developed for quantitative determination of levonorgestrel (LNG) in rat plasma and further validated for specificity, linearity, accuracy, precision, sensitivity, matrix effect, recovery efficiency and stability. Liquid-liquid extraction procedure using hexane:ethyl acetate mixture at 80:20 v:v ratio was employed to efficiently extract LNG from rat plasma. Reversed phase Luna column C18(2) (50×2.0mm i.d., 3μM) installed on a AB SCIEX Triple Quad™ 4500 LC/MS/MS system was used to perform chromatographic separation. LNG was identified within 2min with high specificity. Linear calibration curve was drawn within 0.5-50ng·mL(-1) concentration range. The developed method was validated for intra-day and inter-day accuracy and precision whose values fell in the acceptable limits. Matrix effect was found to be minimal. Recovery efficiency at three quality control (QC) concentrations 0.5 (low), 5 (medium) and 50 (high) ng·mL(-1) was found to be >90%. Stability of LNG at various stages of experiment including storage, extraction and analysis was evaluated using QC samples, and the results showed that LNG was stable at all the conditions. This validated method was successfully used to study the pharmacokinetics of LNG in rats after SubQ injection, providing its applicability in relevant preclinical studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Quality by design: a systematic and rapid liquid chromatography and mass spectrometry method for eprosartan mesylate and its related impurities using a superficially porous particle column.

PubMed

Kalariya, Pradipbhai D; Kumar Talluri, Murali V N; Gaitonde, Vinay D; Devrukhakar, Prashant S; Srinivas, Ragampeta

2014-08-01

The present work describes the systematic development of a robust, precise, and rapid reversed-phase liquid chromatography method for the simultaneous determination of eprosartan mesylate and its six impurities using quality-by-design principles. The method was developed in two phases, screening and optimization. During the screening phase, the most suitable stationary phase, organic modifier, and pH were identified. The optimization was performed for secondary influential parameters--column temperature, gradient time, and flow rate using eight experiments--to examine multifactorial effects of parameters on the critical resolution and generated design space representing the robust region. A verification experiment was performed within the working design space and the model was found to be accurate. This study also describes other operating features of the column packed with superficially porous particles that allow very fast separations at pressures available in most liquid chromatography instruments. Successful chromatographic separation was achieved in less than 7 min using a fused-core C18 (100 mm × 2.1 mm, 2.6 μm) column with linear gradient elution of 10 mM ammonium formate (pH 3.0) and acetonitrile as the mobile phase. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance with the International Conference on Harmonization Q2 (R1) guidelines. The impurities were identified by liquid chromatography with mass spectrometry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous densitometric determination of anthelmintic drug albendazole and its metabolite albendazole sulfoxide by HPTLC in human plasma and pharmaceutical formulations.

PubMed

Pandya, Jui J; Sanyal, Mallika; Shrivastav, Pranav S

2017-09-01

A new, simple, accurate and precise high-performance thin-layer chromatographic method has been developed and validated for simultaneous determination of an anthelmintic drug, albendazole, and its active metabolite albendazole, sulfoxide. Planar chromatographic separation was performed on aluminum-backed layer of silica gel 60G F 254 using a mixture of toluene-acetonitrile-glacial acetic acid (7.0:2.9:0.1, v/v/v) as the mobile phase. For quantitation, the separated spots were scanned densitometrically at 225 nm. The retention factors (R f ) obtained under the established conditions were 0.76 ± 0.01 and 0.50 ± 0.01 and the regression plots were linear (r 2  ≥ 0.9997) in the concentration ranges 50-350 and 100-700 ng/band for albendazole and albendazole sulfoxide, respectively. The method was validated for linearity, specificity, accuracy (recovery) and precision, repeatability, stability and robustness. The limit of detection and limit of quantitation found were 9.84 and 29.81 ng/band for albendazole and 21.60 and 65.45 ng/band for albendazole sulfoxide, respectively. For plasma samples, solid-phase extraction of analytes yielded mean extraction recoveries of 87.59 and 87.13% for albendazole and albendazole sulfoxide, respectively. The method was successfully applied for the analysis of albendazole in pharmaceutical formulations with accuracy ≥99.32%. Copyright © 2017 John Wiley & Sons, Ltd.

Spectrofluorimetric determination of some water-soluble vitamins.

PubMed

Mohamed, Abdel-Maaboud I; Mohamed, Horria A; Abdel-Latif, Niveen M; Mohamed, Marwa R

2011-01-01

Two simple and sensitive spectrofluorimetric methods were developed for determination of three water-soluble vitamins (B1, B2, and B6) in mixtures in the presence of cyanocobalamin. The first one was for thiamine determination, which depends on the oxidation of thiamine HCl to thiochrome by iodine in an alkaline medium. The method was applied accurately to determine thiamine in binary, ternary, and quaternary mixtures with pyridoxine HCl, riboflavin, and cyanocobalamin without interference. In the second method, riboflavin and pyridoxine HCl were determined fluorimetrically in acetate buffer, pH 6. The three water-soluble vitamins (B1, B2, and B6) were determined spectrofluorimetrically in binary, ternary, and quaternary mixtures in the presence of cyanocobalamin. All variables were studied in order to optimize the reaction conditions. Linear relationship was obeyed for all studied vitamins by the proposed methods at their corresponding lambda(exc) or lambda(em). The linear calibration curves were obtained from 10 to 500 ng/mL; the correlation ranged from 0.9991 to 0.9999. The suggested procedures were applied to the analysis of the investigated vitamins in their laboratory-prepared mixtures and pharmaceutical dosage forms from different manufacturers. The RSD range was 0.46-1.02%, which indicates good precision. No interference was observed from common pharmaceutical additives. Good recoveries (97.6 +/- 0.7-101.2 +/- 0.8%) were obtained. Statistical comparison of the results with reported methods shows excellent agreement and indicates no significant difference in accuracy and precision.

Precise montaging and metric quantification of retinal surface area from ultra-widefield fundus photography and fluorescein angiography.

PubMed

Croft, Daniel E; van Hemert, Jano; Wykoff, Charles C; Clifton, David; Verhoek, Michael; Fleming, Alan; Brown, David M

2014-01-01

Accurate quantification of retinal surface area from ultra-widefield (UWF) images is challenging due to warping produced when the retina is projected onto a two-dimensional plane for analysis. By accounting for this, the authors sought to precisely montage and accurately quantify retinal surface area in square millimeters. Montages were created using Optos 200Tx (Optos, Dunfermline, U.K.) images taken at different gaze angles. A transformation projected the images to their correct location on a three-dimensional model. Area was quantified with spherical trigonometry. Warping, precision, and accuracy were assessed. Uncorrected, posterior pixels represented up to 79% greater surface area than peripheral pixels. Assessing precision, a standard region was quantified across 10 montages of the same eye (RSD: 0.7%; mean: 408.97 mm(2); range: 405.34-413.87 mm(2)). Assessing accuracy, 50 patients' disc areas were quantified (mean: 2.21 mm(2); SE: 0.06 mm(2)), and the results fell within the normative range. By accounting for warping inherent in UWF images, precise montaging and accurate quantification of retinal surface area in square millimeters were achieved. Copyright 2014, SLACK Incorporated.

Construction accident narrative classification: An evaluation of text mining techniques.

PubMed

Goh, Yang Miang; Ubeynarayana, C U

2017-11-01

Learning from past accidents is fundamental to accident prevention. Thus, accident and near miss reporting are encouraged by organizations and regulators. However, for organizations managing large safety databases, the time taken to accurately classify accident and near miss narratives will be very significant. This study aims to evaluate the utility of various text mining classification techniques in classifying 1000 publicly available construction accident narratives obtained from the US OSHA website. The study evaluated six machine learning algorithms, including support vector machine (SVM), linear regression (LR), random forest (RF), k-nearest neighbor (KNN), decision tree (DT) and Naive Bayes (NB), and found that SVM produced the best performance in classifying the test set of 251 cases. Further experimentation with tokenization of the processed text and non-linear SVM were also conducted. In addition, a grid search was conducted on the hyperparameters of the SVM models. It was found that the best performing classifiers were linear SVM with unigram tokenization and radial basis function (RBF) SVM with uni-gram tokenization. In view of its relative simplicity, the linear SVM is recommended. Across the 11 labels of accident causes or types, the precision of the linear SVM ranged from 0.5 to 1, recall ranged from 0.36 to 0.9 and F1 score was between 0.45 and 0.92. The reasons for misclassification were discussed and suggestions on ways to improve the performance were provided. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Linear Variable-[theta] Model for Measuring Individual Differences in Response Precision

ERIC Educational Resources Information Center

Ferrando, Pere J.

2011-01-01

Models for measuring individual response precision have been proposed for binary and graded responses. However, more continuous formats are quite common in personality measurement and are usually analyzed with the linear factor analysis model. This study extends the general Gaussian person-fluctuation model to the continuous-response case and…

Double Arm Linkage precision Linear motion (DALL) Carriage, a simplified, rugged, high performance linear motion stage for the moving mirror of an Fourier Transform Spectrometer or other system requiring precision linear motion

NASA Astrophysics Data System (ADS)

Johnson, Kendall B.; Hopkins, Greg

2017-08-01

The Double Arm Linkage precision Linear motion (DALL) carriage has been developed as a simplified, rugged, high performance linear motion stage. Initially conceived as a moving mirror stage for the moving mirror of a Fourier Transform Spectrometer (FTS), it is applicable to any system requiring high performance linear motion. It is based on rigid double arm linkages connecting a base to a moving carriage through flexures. It is a monolithic design. The system is fabricated from one piece of material including the flexural elements, using high precision machining. The monolithic design has many advantages. There are no joints to slip or creep and there are no CTE (coefficient of thermal expansion) issues. This provides a stable, robust design, both mechanically and thermally and is expected to provide a wide operating temperature range, including cryogenic temperatures, and high tolerance to vibration and shock. Furthermore, it provides simplicity and ease of implementation, as there is no assembly or alignment of the mechanism. It comes out of the machining operation aligned and there are no adjustments. A prototype has been fabricated and tested, showing superb shear performance and very promising tilt performance. This makes it applicable to both corner cube and flat mirror FTS systems respectively.

Application of snapshot imaging spectrometer in environmental detection

NASA Astrophysics Data System (ADS)

Sun, Kai; Qin, Xiaolei; Zhang, Yu; Wang, Jinqiang

2017-10-01

This study aimed at the application of snapshot imaging spectrometer in environmental detection. The simulated sewage and dyeing wastewater were prepared and the optimal experimental conditions were determined. The white LED array was used as the detection light source and the image of the sample was collected by the imaging spectrometer developed in the laboratory to obtain the spectral information of the sample in the range of 400-800 nm. The standard curve between the absorbance and the concentration of the samples was established. The linear range of a single component of Rhoda mine B was 1-50 mg/L, the linear correlation coefficient was more than 0.99, the recovery was 93%-113% and the relative standard deviations (RSD) was 7.5%. The linear range of chemical oxygen demand (COD) standard solution was 50-900mg/L, the linear correlation coefficient was 0.981, the recovery was 91% -106% and the relative standard deviation (RSD) was 6.7%. The rapid, accurate and precise method for detecting dyes showed an excellent promise for on-site and emergency detection in environment. At the request of the proceedings editor, an updated version of this article was published on 17 October 2017. The original version of this article was replaced due to an accidental inversion of Figure 2 and Figure 3. The Figures have been corrected in the updated and republished version.

Evaluation for Water Conservation in Agriculture: Using a Multi-Method Econometric Approach

NASA Astrophysics Data System (ADS)

Ramirez, A.; Eaton, D. J.

2012-12-01

Since the 1960's, farmers have implemented new irrigation technology to increase crop production and planting acreage. At that time, technology responded to the increasing demand for food due to world population growth. Currently, the problem of decreased water supply threatens to limit agricultural production. Uncertain precipitation patterns, from prolonged droughts to irregular rains, will continue to hamper planting operations, and farmers are further limited by an increased competition for water from rapidly growing urban areas. Irrigation technology promises to reduce water usage while maintaining or increasing farm yields. The challenge for water managers and policy makers is to quantify and redistribute these efficiency gains as a source of 'new water.' Using conservation in farming as a source of 'new water' requires accurately quantifying the efficiency gains of irrigation technology under farmers' actual operations and practices. From a water resource management and policy perspective, the efficiency gains from conservation in farming can be redistributed to municipal, industrial and recreational uses. This paper presents a methodology that water resource managers can use to statistically verify the water savings attributable to conservation technology. The specific conservation technology examined in this study is precision leveling, and the study includes a mixed-methods approach using four different econometric models: Ordinary Least Squares, Fixed Effects, Propensity Score Matching, and Hierarchical Linear Models. These methods are used for ex-post program evaluation where random assignment is not possible, and they could be employed to evaluate agricultural conservation programs, where participation is often self-selected. The principal method taken in this approach is Hierarchical Linear Models (HLM), a useful model for agriculture because it incorporates the hierarchical nature of the data (fields, tenants, and landowners) as well as crop rotation (fields in and out of production). The other three methods provide verification of the accuracy of the HLM model and create a robust comparison of the water savings estimates. Seventeen factors were used to isolate the effect of precision leveling from variations in climate, investments in other irrigation improvements, and farmers' management skills. These statistical analyses yield accurate water savings estimates because they consider farmers' actual irrigation technology and practices. Results suggest that savings from water conservation technology under farmers' actual production systems and management are less than those reported by experimental field studies. These water savings measure the 'in situ' effect of the technology, considering farmers' actual irrigation practices and technology. In terms of the accuracy of the models, HLM provides the most precise estimate of the impact of precision leveling on a field's water usage. The HLM estimate was within the 95% confidence interval of the other three models, thus verifying the accuracy and robustness of the statistical findings and model.

An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system

PubMed Central

Hinke, Jefferson T.; Perryman, Wayne L.; Goebel, Michael E.; LeRoi, Donald J.

2017-01-01

Measurements of body size and mass are fundamental to pinniped population management and research. Manual measurements tend to be accurate but are invasive and logistically challenging to obtain. Ground-based photogrammetric techniques are less invasive, but inherent limitations make them impractical for many field applications. The recent proliferation of unmanned aerial systems (UAS) in wildlife monitoring has provided a promising new platform for the photogrammetry of free-ranging pinnipeds. Leopard seals (Hydrurga leptonyx) are an apex predator in coastal Antarctica whose body condition could be a valuable indicator of ecosystem health. We aerially surveyed leopard seals of known body size and mass to test the precision and accuracy of photogrammetry from a small UAS. Flights were conducted in January and February of 2013 and 2014 and 50 photogrammetric samples were obtained from 15 unrestrained seals. UAS-derived measurements of standard length were accurate to within 2.01 ± 1.06%, and paired comparisons with ground measurements were statistically indistinguishable. An allometric linear mixed effects model predicted leopard seal mass within 19.40 kg (4.4% error for a 440 kg seal). Photogrammetric measurements from a single, vertical image obtained using UAS provide a noninvasive approach for estimating the mass and body condition of pinnipeds that may be widely applicable. PMID:29186134

The key particle and quark energy equality E W + E Z = E top

NASA Astrophysics Data System (ADS)

Mac Gregor, Malcolm H.

2017-11-01

Precision Tevatron and Linear Hadron Collider measurements at Fermilab and CERN have revealed the numerically accurate mass equality W + Z = t. This equality between two gauge bosons ( gb) and the top quark t is only valid if reinterpreted as an energy equality, where E = mc 2, since energy is a shared property of particles and quarks. The experimental data indicate that the LHC particle excitation energy is quantized in the form of gauge boson energy packets E gb , which are created by factor-of-137 proton-quark energy increases denoted as α- boosts, where α 1/137 is the fine structure constant. These α-boosts occur during the rare head-on quark-quark collisions in the proton beams. The α-boost energy quantization mechanism also occurs in low-energy electron-positron boson and fermion particle production channels, where it generates E b and E f energy packets. These α-boost energy channels link together coherently, as demonstrated by the accurate top quark energy equation E top = (18/α2) E electron. Particle production energy equations are derived which combine to create an overall energy pattern that accurately reproduces the energies of the ( u, d), s, c, b, t fermion constituent quarks, the µ and τ leptons, and the proton.

An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system.

PubMed

Krause, Douglas J; Hinke, Jefferson T; Perryman, Wayne L; Goebel, Michael E; LeRoi, Donald J

2017-01-01

Measurements of body size and mass are fundamental to pinniped population management and research. Manual measurements tend to be accurate but are invasive and logistically challenging to obtain. Ground-based photogrammetric techniques are less invasive, but inherent limitations make them impractical for many field applications. The recent proliferation of unmanned aerial systems (UAS) in wildlife monitoring has provided a promising new platform for the photogrammetry of free-ranging pinnipeds. Leopard seals (Hydrurga leptonyx) are an apex predator in coastal Antarctica whose body condition could be a valuable indicator of ecosystem health. We aerially surveyed leopard seals of known body size and mass to test the precision and accuracy of photogrammetry from a small UAS. Flights were conducted in January and February of 2013 and 2014 and 50 photogrammetric samples were obtained from 15 unrestrained seals. UAS-derived measurements of standard length were accurate to within 2.01 ± 1.06%, and paired comparisons with ground measurements were statistically indistinguishable. An allometric linear mixed effects model predicted leopard seal mass within 19.40 kg (4.4% error for a 440 kg seal). Photogrammetric measurements from a single, vertical image obtained using UAS provide a noninvasive approach for estimating the mass and body condition of pinnipeds that may be widely applicable.

Sex differences in accuracy and precision when judging time to arrival: data from two Internet studies.

PubMed

Sanders, Geoff; Sinclair, Kamila

2011-12-01

We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering.

The Too-Much-Precision Effect.

PubMed

Loschelder, David D; Friese, Malte; Schaerer, Michael; Galinsky, Adam D

2016-12-01

Past research has suggested a fundamental principle of price precision: The more precise an opening price, the more it anchors counteroffers. The present research challenges this principle by demonstrating a too-much-precision effect. Five experiments (involving 1,320 experts and amateurs in real-estate, jewelry, car, and human-resources negotiations) showed that increasing the precision of an opening offer had positive linear effects for amateurs but inverted-U-shaped effects for experts. Anchor precision backfired because experts saw too much precision as reflecting a lack of competence. This negative effect held unless first movers gave rationales that boosted experts' perception of their competence. Statistical mediation and experimental moderation established the critical role of competence attributions. This research disentangles competing theoretical accounts (attribution of competence vs. scale granularity) and qualifies two putative truisms: that anchors affect experts and amateurs equally, and that more precise prices are linearly more potent anchors. The results refine current theoretical understanding of anchoring and have significant implications for everyday life.

iXora: exact haplotype inferencing and trait association.

PubMed

Utro, Filippo; Haiminen, Niina; Livingstone, Donald; Cornejo, Omar E; Royaert, Stefan; Schnell, Raymond J; Motamayor, Juan Carlos; Kuhn, David N; Parida, Laxmi

2013-06-06

We address the task of extracting accurate haplotypes from genotype data of individuals of large F1 populations for mapping studies. While methods for inferring parental haplotype assignments on large F1 populations exist in theory, these approaches do not work in practice at high levels of accuracy. We have designed iXora (Identifying crossovers and recombining alleles), a robust method for extracting reliable haplotypes of a mapping population, as well as parental haplotypes, that runs in linear time. Each allele in the progeny is assigned not just to a parent, but more precisely to a haplotype inherited from the parent. iXora shows an improvement of at least 15% in accuracy over similar systems in literature. Furthermore, iXora provides an easy-to-use, comprehensive environment for association studies and hypothesis checking in populations of related individuals. iXora provides detailed resolution in parental inheritance, along with the capability of handling very large populations, which allows for accurate haplotype extraction and trait association. iXora is available for non-commercial use from http://researcher.ibm.com/project/3430.

Application of Certain π-Acceptors for the Spectrophotometric Determination of Alendronate Sodium in Pharmaceutical Bulk and Dosage Forms.

PubMed

Raza, Asad; Zia-Ul-Haq, Muhammad

2011-01-01

Two simple, fast, and accurate spectrophotometric methods for the determination of alendronate sodium are described. The methods are based on charge-transfer complex formation of the drug with two π-electron acceptors 7,7,7,8-tetracyanoquinodimethane (TCNQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in acetonitrile and methanol medium. The methods are followed spectrophotometrically by measuring the maximum absorbance at 840 nm and 465 nm, respectively. Under the optimized experimental conditions, the calibration curves showed a linear relationship over the concentration ranges of 2-10 μg mL(-1) and 2-12 μg mL(-1), respectively. The optimal reactions conditions values such as the reagent concentration, heating time, and stability of reaction product were determined. No significant difference was obtained between the results of newly proposed methods and the B.P. Titrimetric procedures. The charge transfer approach using TCNQ and DDQ procedures described in this paper is simple, fast, accurate, precise, and extraction-free.

Precession technique and electron diffractometry as new tools for crystal structure analysis and chemical bonding determination.

PubMed

Avilov, A; Kuligin, K; Nicolopoulos, S; Nickolskiy, M; Boulahya, K; Portillo, J; Lepeshov, G; Sobolev, B; Collette, J P; Martin, N; Robins, A C; Fischione, P

2007-01-01

We have developed a new fast electron diffractometer working with high dynamic range and linearity for crystal structure determinations. Electron diffraction (ED) patterns can be scanned serially in front of a Faraday cage detector; the total measurement time for several hundred ED reflections can be tens of seconds having high statistical accuracy for all measured intensities (1-2%). This new tool can be installed to any type of TEM without any column modification and is linked to a specially developed electron beam precession "Spinning Star" system. Precession of the electron beam (Vincent-Midgley technique) reduces dynamical effects allowing also use of accurate intensities for crystal structure analysis. We describe the technical characteristics of this new tool together with the first experimental results. Accurate measurement of electron diffraction intensities by electron diffractometer opens new possibilities not only for revealing unknown structures, but also for electrostatic potential determination and chemical bonding investigation. As an example, we present detailed atomic bonding information of CaF(2) as revealed for the first time by precise electron diffractometry.

Application of Certain π-Acceptors for the Spectrophotometric Determination of Alendronate Sodium in Pharmaceutical Bulk and Dosage Forms

PubMed Central

Raza, Asad; Zia-ul-Haq, Muhammad

2011-01-01

Two simple, fast, and accurate spectrophotometric methods for the determination of alendronate sodium are described. The methods are based on charge-transfer complex formation of the drug with two π-electron acceptors 7,7,7,8-tetracyanoquinodimethane (TCNQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in acetonitrile and methanol medium. The methods are followed spectrophotometrically by measuring the maximum absorbance at 840 nm and 465 nm, respectively. Under the optimized experimental conditions, the calibration curves showed a linear relationship over the concentration ranges of 2–10 μg mL−1 and 2–12 μg mL−1, respectively. The optimal reactions conditions values such as the reagent concentration, heating time, and stability of reaction product were determined. No significant difference was obtained between the results of newly proposed methods and the B.P. Titrimetric procedures. The charge transfer approach using TCNQ and DDQ procedures described in this paper is simple, fast, accurate, precise, and extraction-free. PMID:21760789

Nonlinear Contact Effects in Staggered Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Fischer, Axel; Zündorf, Hilke; Kaschura, Felix; Widmer, Johannes; Leo, Karl; Kraft, Ulrike; Klauk, Hagen

2017-11-01

The static and dynamic electrical characteristics of thin-film transistors (TFTs) are often limited by the parasitic contact resistances, especially for TFTs with a small channel length. For the smallest possible contact resistance, the staggered device architecture has a general advantage over the coplanar architecture of a larger injection area. Since the charge transport occurs over an extended area, it is inherently more difficult to develop an accurate analytical device model for staggered TFTs. Most analytical models for staggered TFTs, therefore, assume that the contact resistance is linear, even though this is commonly accepted not to be the case. Here, we introduce a semiphenomenological approach to accurately fit experimental data based on a highly discretized equivalent network circuit explicitly taking into account the inherent nonlinearity of the contact resistance. The model allows us to investigate the influence of nonlinear contact resistances on the static and dynamic performance of staggered TFTs for different contact layouts with a relatively short computation time. The precise extraction of device parameters enables us to calculate the transistor behavior as well as the potential for optimization in real circuits.

Advanced 3D image processing techniques for liver and hepatic tumor location and volumetry

NASA Astrophysics Data System (ADS)

Chemouny, Stephane; Joyeux, Henri; Masson, Bruno; Borne, Frederic; Jaeger, Marc; Monga, Olivier

1999-05-01

To assist radiologists and physicians in diagnosing, and in treatment planning and evaluating in liver oncology, we have developed a fast and accurate segmentation of the liver and its lesions within CT-scan exams. The first step of our method is to reduce spatial resolution of CT images. This will have two effects: obtain near isotropic 3D data space and drastically decrease computational time for further processing. On a second step a 3D non-linear `edge- preserving' smoothing filtering is performed throughout the entire exam. On a third step the 3D regions coming out from the second step are homogeneous enough to allow a quite simple segmentation process, based on morphological operations, under supervisor control, ending up with accurate 3D regions of interest (ROI) of the liver and all the hepatic tumors. On a fourth step the ROIs are eventually set back into the original images, features like volume and location are immediately computed and displayed. The segmentation we get is as precise as a manual one but is much faster.

Design, development and validation of a new laryngo-pharyngeal endoscopic esthesiometer and range-finder based on the assessment of air-pulse variability determinants.

PubMed

Giraldo-Cadavid, Luis F; Agudelo-Otalora, Luis Mauricio; Burguete, Javier; Arbulu, Mario; Moscoso, William Daniel; Martínez, Fabio; Ortiz, Andrés Felipe; Diaz, Juan; Pantoja, Jaime A; Rueda-Arango, Andrés Felipe; Fernández, Secundino

2016-05-10

Laryngo-pharyngeal mechano-sensitivity (LPMS) is involved in dysphagia, sleep apnea, stroke, irritable larynx syndrome and cough hypersensitivity syndrome among other disorders. These conditions are associated with a wide range of airway reflex abnormalities. However, the current device for exploring LPMS is limited because it assesses only the laryngeal adductor reflex during fiber-optic endoscopic evaluations of swallowing and requires a high degree of expertise to obtain reliable results, introducing intrinsic expert variability and subjectivity. We designed, developed and validated a new air-pulse laryngo-pharyngeal endoscopic esthesiometer with a built-in laser range-finder (LPEER) based on the evaluation and control of air-pulse variability determinants and on intrinsic observer variability and subjectivity determinants of the distance, angle and site of stimulus impact. The LPEER was designed to be capable of delivering precise and accurate stimuli with a wide range of intensities that can explore most laryngo-pharyngeal reflexes. We initially explored the potential factors affecting the reliability of LPMS tests and included these factors in a multiple linear regression model. The following factors significantly affected the precision and accuracy of the test (P < 0.001): the tube conducting the air-pulses, the supply pressure of the system, the duration of the air-pulses, and the distance and angle between the end of the tube conducting the air-pulses and the site of impact. To control all of these factors, an LPEER consisting of an air-pulse generator and an endoscopic laser range-finder was designed and manufactured. We assessed the precision and accuracy of the LPEER's stimulus and range-finder according to the coefficient of variation (CV) and by looking at the differences between the measured properties and the desired values, and we performed a pilot validation on ten human subjects. The air-pulses and range-finder exhibited good precision and accuracy (CV < 0.06), with differences between the desired and measured properties at <3 % and a range-finder measurement error of <1 mm. The tests in patients demonstrated obtainable and reproducible thresholds for the laryngeal adductor, cough and gag reflexes. The new LPEER was capable of delivering precise and accurate stimuli for exploring laryngo-pharyngeal reflexes.

Robotic-Arm Assisted Total Knee Arthroplasty Demonstrated Greater Accuracy and Precision to Plan Compared with Manual Techniques.

PubMed

Hampp, Emily L; Chughtai, Morad; Scholl, Laura Y; Sodhi, Nipun; Bhowmik-Stoker, Manoshi; Jacofsky, David J; Mont, Michael A

2018-05-01

This study determined if robotic-arm assisted total knee arthroplasty (RATKA) allows for more accurate and precise bone cuts and component position to plan compared with manual total knee arthroplasty (MTKA). Specifically, we assessed the following: (1) final bone cuts, (2) final component position, and (3) a potential learning curve for RATKA. On six cadaver specimens (12 knees), a MTKA and RATKA were performed on the left and right knees, respectively. Bone-cut and final-component positioning errors relative to preoperative plans were compared. Median errors and standard deviations (SDs) in the sagittal, coronal, and axial planes were compared. Median values of the absolute deviation from plan defined the accuracy to plan. SDs described the precision to plan. RATKA bone cuts were as or more accurate to plan based on nominal median values in 11 out of 12 measurements. RATKA bone cuts were more precise to plan in 8 out of 12 measurements ( p  ≤ 0.05). RATKA final component positions were as or more accurate to plan based on median values in five out of five measurements. RATKA final component positions were more precise to plan in four out of five measurements ( p  ≤ 0.05). Stacked error results from all cuts and implant positions for each specimen in procedural order showed that RATKA error was less than MTKA error. Although this study analyzed a small number of cadaver specimens, there were clear differences that separated these two groups. When compared with MTKA, RATKA demonstrated more accurate and precise bone cuts and implant positioning to plan. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Network-induced chaos in integrate-and-fire neuronal ensembles.

PubMed

Zhou, Douglas; Rangan, Aaditya V; Sun, Yi; Cai, David

2009-09-01

It has been shown that a single standard linear integrate-and-fire (IF) neuron under a general time-dependent stimulus cannot possess chaotic dynamics despite the firing-reset discontinuity. Here we address the issue of whether conductance-based, pulsed-coupled network interactions can induce chaos in an IF neuronal ensemble. Using numerical methods, we demonstrate that all-to-all, homogeneously pulse-coupled IF neuronal networks can indeed give rise to chaotic dynamics under an external periodic current drive. We also provide a precise characterization of the largest Lyapunov exponent for these high dimensional nonsmooth dynamical systems. In addition, we present a stable and accurate numerical algorithm for evaluating the largest Lyapunov exponent, which can overcome difficulties encountered by traditional methods for these nonsmooth dynamical systems with degeneracy induced by, e.g., refractoriness of neurons.

[Simultaneous determination of five active constitutents in Xiaochaihu Tang by HPLC].

PubMed

Liu, Qingchun; Zhao, Junning; Yan, Liangchun; Yi, Jinhai; Song, Jun

2010-03-01

To establish a HPLC-PDA method for the determination of baicalin, wogonoside, baicalein, wogonin and glycyrrhizic acid in Xiaochaihu Tang. A Symmetry Shield RP18 (4.6 mm x 250 mm, 5.0 microm) was used with a mobile phase of acetonitrile-0.01% H3PO4 in gradient elution. The detection wavelength was 251 nm,the flow rate was 0.45 mL x min(-1) and the column temperature was maintained at 30 degrees C. The accuracy, precision, sensitivity, specificity and linearity of this method met the requirements. The contents of the five effective fractions were determined simultaneously. The method is rapid,simple and accurate and it can be suitable for the determination of baicalin, wogonoside, baicalein, wogonin and glycyrrhizic acid in Xiaochaihu Tang simultaneously.

On cup anemometer rotor aerodynamics.

PubMed

Pindado, Santiago; Pérez, Javier; Avila-Sanchez, Sergio

2012-01-01

The influence of anemometer rotor shape parameters, such as the cups' front area or their center rotation radius on the anemometer's performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups' center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor's cup.

Improving the sensitivity and specificity of a bioanalytical assay for the measurement of certolizumab pegol.

PubMed

Smeraglia, John; Silva, John-Paul; Jones, Kieran

2017-08-01

In order to evaluate placental transfer of certolizumab pegol (CZP), a more sensitive and selective bioanalytical assay was required to accurately measure low CZP concentrations in infant and umbilical cord blood. Results & methodology: A new electrochemiluminescence immunoassay was developed to measure CZP levels in human plasma. Validation experiments demonstrated improved selectivity (no matrix interference observed) and a detection range of 0.032-5.0 μg/ml. Accuracy and precision met acceptance criteria (mean total error ≤20.8%). Dilution linearity and sample stability were acceptable and sufficient to support the method. The electrochemiluminescence immunoassay was validated for measuring low CZP concentrations in human plasma. The method demonstrated a more than tenfold increase in sensitivity compared with previous assays, and improved selectivity for intact CZP.

Initialization of a fractional order identification algorithm applied for Lithium-ion battery modeling in time domain

NASA Astrophysics Data System (ADS)

Nasser Eddine, Achraf; Huard, Benoît; Gabano, Jean-Denis; Poinot, Thierry

2018-06-01

This paper deals with the initialization of a non linear identification algorithm used to accurately estimate the physical parameters of Lithium-ion battery. A Randles electric equivalent circuit is used to describe the internal impedance of the battery. The diffusion phenomenon related to this modeling is presented using a fractional order method. The battery model is thus reformulated into a transfer function which can be identified through Levenberg-Marquardt algorithm to ensure the algorithm's convergence to the physical parameters. An initialization method is proposed in this paper by taking into account previously acquired information about the static and dynamic system behavior. The method is validated using noisy voltage response, while precision of the final identification results is evaluated using Monte-Carlo method.

AITRAC: Augmented Interactive Transient Radiation Analysis by Computer. User's information manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1977-10-01

AITRAC is a program designed for on-line, interactive, DC, and transient analysis of electronic circuits. The program solves linear and nonlinear simultaneous equations which characterize the mathematical models used to predict circuit response. The program features 100 external node--200 branch capability; conversional, free-format input language; built-in junction, FET, MOS, and switch models; sparse matrix algorithm with extended-precision H matrix and T vector calculations, for fast and accurate execution; linear transconductances: beta, GM, MU, ZM; accurate and fast radiation effects analysis; special interface for user-defined equations; selective control of multiple outputs; graphical outputs in wide and narrow formats; and on-line parametermore » modification capability. The user describes the problem by entering the circuit topology and part parameters. The program then automatically generates and solves the circuit equations, providing the user with printed or plotted output. The circuit topology and/or part values may then be changed by the user, and a new analysis, requested. Circuit descriptions may be saved on disk files for storage and later use. The program contains built-in standard models for resistors, voltage and current sources, capacitors, inductors including mutual couplings, switches, junction diodes and transistors, FETS, and MOS devices. Nonstandard models may be constructed from standard models or by using the special equations interface. Time functions may be described by straight-line segments or by sine, damped sine, and exponential functions. 42 figures, 1 table. (RWR)« less

3D volumetry comparison using 3T magnetic resonance imaging between normal and adenoma-containing pituitary glands.

PubMed

Roldan-Valadez, Ernesto; Garcia-Ulloa, Ana Cristina; Gonzalez-Gutierrez, Omar; Martinez-Lopez, Manuel

2011-01-01

Computed-assisted three-dimensional data (3D) allows for an accurate evaluation of volumes compared with traditional measurements. An in vitro method comparison between geometric volume and 3D volumetry to obtain reference data for pituitary volumes in normal pituitary glands (PGs) and PGs containing adenomas. Prospective, transverse, analytical study. Forty-eight subjects underwent brain magnetic resonance imaging (MRI) with 3D sequencing for computer-aided volumetry. PG phantom volumes by both methods were compared. Using the best volumetric method, volumes of normal PGs and PGs with adenoma were compared. Statistical analysis used the Bland-Altman method, t-statistics, effect size and linear regression analysis. Method comparison between 3D volumetry and geometric volume revealed a lower bias and precision for 3D volumetry. A total of 27 patients exhibited normal PGs (mean age, 42.07 ± 16.17 years), although length, height, width, geometric volume and 3D volumetry were greater in women than in men. A total of 21 patients exhibited adenomas (mean age 39.62 ± 10.79 years), and length, height, width, geometric volume and 3D volumetry were greater in men than in women, with significant volumetric differences. Age did not influence pituitary volumes on linear regression analysis. Results from the present study showed that 3D volumetry was more accurate than the geometric method. In addition, the upper normal limits of PGs overlapped with lower volume limits during early stage microadenomas.

Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: organic carbon

NASA Astrophysics Data System (ADS)

Dillner, A. M.; Takahama, S.

2014-11-01

Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, the organic carbon concentration is measured using thermal methods such as Thermal-Optical Reflectance (TOR) from quartz fiber filters. Here, methods are presented whereby Fourier Transform Infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters are used to accurately predict TOR OC. Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filters. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites sampled during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to artifact-corrected TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date which leads to precise and accurate OC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), low bias (0.02 μg m-3, all μg m-3 values based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. FT-IR spectra are also divided into calibration and test sets by OC mass and by OM / OC which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; this division also leads to precise and accurate OC predictions. Low OC concentrations have higher bias and normalized error due to TOR analytical errors and artifact correction errors, not due to the range of OC mass of the samples in the calibration set. However, samples with low OC mass can be used to predict samples with high OC mass indicating that the calibration is linear. Using samples in the calibration set that have a different OM / OC or ammonium / OC distributions than the test set leads to only a modest increase in bias and normalized error in the predicted samples. We conclude that FT-IR analysis with partial least squares regression is a robust method for accurately predicting TOR OC in IMPROVE network samples; providing complementary information to the organic functional group composition and organic aerosol mass estimated previously from the same set of sample spectra (Ruthenburg et al., 2014).

Perceptual scale expansion: an efficient angular coding strategy for locomotor space.

PubMed

Durgin, Frank H; Li, Zhi

2011-08-01

Whereas most sensory information is coded on a logarithmic scale, linear expansion of a limited range may provide a more efficient coding for the angular variables important to precise motor control. In four experiments, we show that the perceived declination of gaze, like the perceived orientation of surfaces, is coded on a distorted scale. The distortion seems to arise from a nearly linear expansion of the angular range close to horizontal/straight ahead and is evident in explicit verbal and nonverbal measures (Experiments 1 and 2), as well as in implicit measures of perceived gaze direction (Experiment 4). The theory is advanced that this scale expansion (by a factor of about 1.5) may serve a functional goal of coding efficiency for angular perceptual variables. The scale expansion of perceived gaze declination is accompanied by a corresponding expansion of perceived optical slants in the same range (Experiments 3 and 4). These dual distortions can account for the explicit misperception of distance typically obtained by direct report and exocentric matching, while allowing for accurate spatial action to be understood as the result of calibration.

Elastic and mechanical softening in boron-doped diamond

PubMed Central

Liu, Xiaobing; Chang, Yun-Yuan; Tkachev, Sergey N.; Bina, Craig R.; Jacobsen, Steven D.

2017-01-01

Alternative approaches to evaluating the hardness and elastic properties of materials exhibiting physical properties comparable to pure diamond have recently become necessary. The classic linear relationship between shear modulus (G) and Vickers hardness (HV), along with more recent non-linear formulations based on Pugh’s modulus extending into the superhard region (HV > 40 GPa) have guided synthesis and identification of novel superabrasives. These schemes rely on accurately quantifying HV of diamond-like materials approaching or potentially exceeding the hardness of the diamond indenter, leading to debate about methodology and the very definition of hardness. Elasticity measurements on such materials are equally challenging. Here we used a high-precision, GHz-ultrasonic interferometer in conjunction with a newly developed optical contact micrometer and 3D optical microscopy of indentations to evaluate elasticity-hardness relations in the ultrahard range (HV > 80 GPa) by examining single-crystal boron-doped diamond (BDD) with boron contents ranging from 50–3000 ppm. We observe a drastic elastic-mechanical softening in highly doped BDD relative to the trends observed for superhard materials, providing insight into elasticity-hardness relations for ultrahard materials. PMID:28233808

Perceptual Scale Expansion: An Efficient Angular Coding Strategy for Locomotor Space

PubMed Central

Durgin, Frank H.; Li, Zhi

2011-01-01

Whereas most sensory information is coded in a logarithmic scale, linear expansion of a limited range may provide a more efficient coding for angular variables important to precise motor control. In four experiments it is shown that the perceived declination of gaze, like the perceived orientation of surfaces is coded on a distorted scale. The distortion seems to arise from a nearly linear expansion of the angular range close to horizontal/straight ahead and is evident in explicit verbal and non-verbal measures (Experiments 1 and 2) and in implicit measures of perceived gaze direction (Experiment 4). The theory is advanced that this scale expansion (by a factor of about 1.5) may serve a functional goal of coding efficiency for angular perceptual variables. The scale expansion of perceived gaze declination is accompanied by a corresponding expansion of perceived optical slants in the same range (Experiments 3 and 4). These dual distortions can account for the explicit misperception of distance typically obtained by direct report and exocentric matching while allowing accurate spatial action to be understood as the result of calibration. PMID:21594732

Scattering matrix approach to the dissociative recombination of HCO{sup +} and N{sub 2}H{sup +}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fonseca dos Santos, S.; Douguet, N.; Orel, A. E.

We present a theoretical study of the indirect dissociative recombination of linear polyatomic ions at low collisional energies. The approach is based on the computation of the scattering matrix just above the ionization threshold and enables the explicit determination of all diabatic electronic couplings responsible for dissociative recombination. In addition, we use the multi-channel quantum-defect theory to demonstrate the precision of the scattering matrix by reproducing accurately ab initio Rydberg state energies of the neutral molecule. We consider the molecular ions N{sub 2}H{sup +} and HCO{sup +} as benchmark systems of astrophysical interest and improve former theoretical studies, which hadmore » repeatedly produced smaller cross sections than experimentally measured. Specifically, we demonstrate the crucial role of the previously overlooked stretching modes for linear polyatomic ions with large permanent dipole moment. The theoretical cross sections for both ions agree well with experimental data over a wide energy range. Finally, we consider the potential role of the HOC{sup +} isomer in the experimental cross sections of HCO{sup +} at energies below 10 meV.« less

Simultaneous determination of atorvastatin calcium, ezetimibe, and fenofibrate in a tablet formulation by HPLC.

PubMed

Patel, Archita; Macwana, Chhaya; Parmar, Vishal; Patel, Samir

2012-01-01

An accurate, simple, reproducible, and sensitive HPLC method was developed and validated for the simultaneous determination of atorvastatin calcium, ezetimibe, and fenofibrate in a tablet formulation. The analyses were performed on an RP C18 column, 150 x 4.60 mm id, 5 pm particle size. The mobile phase methanol-acetonitrile-water (76 + 13 + 11, v/v/v), was pumped at a constant flow rate of 1 mL/min. UV detection was performed at 253 nm. Retention times of atorvastatin calcium, ezetimibe, and fenofibrate were found to be 2.25, 3.68, and 6.41 min, respectively. The method was validated in terms of linearity, precision, accuracy, LOD, LOQ, and robustness. The response was linear in the range 2-10 microg/mL (r2 = 0.998) for atorvastatin calcium, 2-10 microg/mL (r2 = 0.998) for ezetimibe, and 40-120 microg/mL (r2 = 0.998) for fenofibrate. The developed method can be used for routine quality analysis of the drugs in the tablet formulation.

Elastic and mechanical softening in boron-doped diamond

NASA Astrophysics Data System (ADS)

Liu, Xiaobing; Chang, Yun-Yuan; Tkachev, Sergey N.; Bina, Craig R.; Jacobsen, Steven D.

2017-02-01

Alternative approaches to evaluating the hardness and elastic properties of materials exhibiting physical properties comparable to pure diamond have recently become necessary. The classic linear relationship between shear modulus (G) and Vickers hardness (HV), along with more recent non-linear formulations based on Pugh’s modulus extending into the superhard region (HV > 40 GPa) have guided synthesis and identification of novel superabrasives. These schemes rely on accurately quantifying HV of diamond-like materials approaching or potentially exceeding the hardness of the diamond indenter, leading to debate about methodology and the very definition of hardness. Elasticity measurements on such materials are equally challenging. Here we used a high-precision, GHz-ultrasonic interferometer in conjunction with a newly developed optical contact micrometer and 3D optical microscopy of indentations to evaluate elasticity-hardness relations in the ultrahard range (HV > 80 GPa) by examining single-crystal boron-doped diamond (BDD) with boron contents ranging from 50-3000 ppm. We observe a drastic elastic-mechanical softening in highly doped BDD relative to the trends observed for superhard materials, providing insight into elasticity-hardness relations for ultrahard materials.

Testing and linearity calibration of films of phenol compounds exposed to thermal neutron field for EPR dosimetry.

PubMed

Gallo, S; Panzeca, S; Longo, A; Altieri, S; Bentivoglio, A; Dondi, D; Marconi, R P; Protti, N; Zeffiro, A; Marrale, M

2015-12-01

This paper reports the preliminary results obtained by Electron Paramagnetic Resonance (EPR) measurements on films of IRGANOX® 1076 phenols with and without low content (5% by weight) of gadolinium oxide (Gd2O3) exposed in the thermal column of the Triga Mark II reactor of LENA (Laboratorio Energia Nucleare Applicata) of Pavia (Italy). Thanks to their size, the phenolic films here presented are good devices for the dosimetry of beams with high dose gradient and which require accurate knowledge of the precise dose delivered. The dependence of EPR signal as function of neutron dose was investigated in the fluence range between 10(11) cm(-2) and 10(14) cm(-2). Linearity of EPR response was found and the signal was compared with that of commercial alanine films. Our analysis showed that gadolinium oxide (5% by weight) can enhance the thermal neutron sensitivity more than 18 times. Irradiated dosimetric films of phenolic compound exhibited EPR signal fading of about 4% after 10 days from irradiation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development and validation of an HPLC method to quantify camptothecin in polymeric nanocapsule suspensions.

PubMed

Granada, Andréa; Murakami, Fabio S; Sartori, Tatiane; Lemos-Senna, Elenara; Silva, Marcos A S

2008-01-01

A simple, rapid, and sensitive reversed-phase column high-performance liquid chromatographic method was developed and validated to quantify camptothecin (CPT) in polymeric nanocapsule suspensions. The chromatographic separation was performed on a Supelcosil LC-18 column (15 cm x 4.6 mm id, 5 microm) using a mobile phase consisting of methanol-10 mM KH2PO4 (60 + 40, v/v; pH 2.8) at a flow rate of 1.0 mL/min and ultraviolet detection at 254 nm. The calibration graph was linear from 0.5 to 3.0 microg/mL with a correlation coefficient of 0.9979, and the limit of quantitation was 0.35 microg/mL. The assay recovery ranged from 97.3 to 105.0%. The intraday and interday relative standard deviation values were < 5.0%. The validation results confirmed that the developed method is specific, linear, accurate, and precise for its intended use. The current method was successfully applied to the evaluation of CPT entrapment efficiency and drug content in polymeric nanocapsule suspensions during the early stage of formulation development.

High spatial precision nano-imaging of polarization-sensitive plasmonic particles

NASA Astrophysics Data System (ADS)

Liu, Yunbo; Wang, Yipei; Lee, Somin Eunice

2018-02-01

Precise polarimetric imaging of polarization-sensitive nanoparticles is essential for resolving their accurate spatial positions beyond the diffraction limit. However, conventional technologies currently suffer from beam deviation errors which cannot be corrected beyond the diffraction limit. To overcome this issue, we experimentally demonstrate a spatially stable nano-imaging system for polarization-sensitive nanoparticles. In this study, we show that by integrating a voltage-tunable imaging variable polarizer with optical microscopy, we are able to suppress beam deviation errors. We expect that this nano-imaging system should allow for acquisition of accurate positional and polarization information from individual nanoparticles in applications where real-time, high precision spatial information is required.

Practical Application of Linear Growth Measurements in Clinical Research in Low- and Middle-Income Countries

PubMed Central

Wit, Jan M.; Himes, John H.; van Buuren, Stef; Denno, Donna M.; Suchdev, Parminder S.

2017-01-01

Background/Aims Childhood stunting is a prevalent problem in low- and middle-income countries and is associated with long-term adverse neurodevelopment and health outcomes. In this review, we define indicators of growth, discuss key challenges in their analysis and application, and offer suggestions for indicator selection in clinical research contexts. Methods Critical review of the literature. Results Linear growth is commonly expressed as length-for-age or height-for-age z-score (HAZ) in comparison to normative growth standards. Conditional HAZ corrects for regression to the mean where growth changes relate to previous status. In longitudinal studies, growth can be expressed as ΔHAZ at 2 time points. Multilevel modeling is preferable when more measurements per individual child are available over time. Height velocity z-score reference standards are available for children under the age of 2 years. Adjusting for covariates or confounders (e.g., birth weight, gestational age, sex, parental height, maternal education, socioeconomic status) is recommended in growth analyses. Conclusion The most suitable indicator(s) for linear growth can be selected based on the number of available measurements per child and the child's age. By following a step-by-step algorithm, growth analyses can be precisely and accurately performed to allow for improved comparability within and between studies. PMID:28196362

Application of High-Performance Liquid Chromatography Coupled with Linear Ion Trap Quadrupole Orbitrap Mass Spectrometry for Qualitative and Quantitative Assessment of Shejin-Liyan Granule Supplements.

PubMed

Gu, Jifeng; Wu, Weijun; Huang, Mengwei; Long, Fen; Liu, Xinhua; Zhu, Yizhun

2018-04-11

A method for high-performance liquid chromatography coupled with linear ion trap quadrupole Orbitrap high-resolution mass spectrometry (HPLC-LTQ-Orbitrap MS) was developed and validated for the qualitative and quantitative assessment of Shejin-liyan Granule. According to the fragmentation mechanism and high-resolution MS data, 54 compounds, including fourteen isoflavones, eleven ligands, eight flavonoids, six physalins, six organic acids, four triterpenoid saponins, two xanthones, two alkaloids, and one licorice coumarin, were identified or tentatively characterized. In addition, ten of the representative compounds (matrine, galuteolin, tectoridin, iridin, arctiin, tectorigenin, glycyrrhizic acid, irigenin, arctigenin, and irisflorentin) were quantified using the validated HPLC-LTQ-Orbitrap MS method. The method validation showed a good linearity with coefficients of determination (r²) above 0.9914 for all analytes. The accuracy of the intra- and inter-day variation of the investigated compounds was 95.0-105.0%, and the precision values were less than 4.89%. The mean recoveries and reproducibilities of each analyte were 95.1-104.8%, with relative standard deviations below 4.91%. The method successfully quantified the ten compounds in Shejin-liyan Granule, and the results show that the method is accurate, sensitive, and reliable.

The Spectropolarimeter for Planetary Exploration: SPEX

NASA Astrophysics Data System (ADS)

Laan, Erik; Stam, Daphne; Snik, Frans; Karalidi, Theodora; Keller, Christoph; ter Horst, Rik; Navarro, Ramon; Oomen, Gijsbert; de Vries, Johan; Hoogeveen, Ruud

2017-11-01

SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact remotesensing instrument for measuring and characterizing aerosols in the atmosphere. The shoebox size instrument is capable of accurate full linear spectropolarimetry without moving parts or liquid crystals. High precision polarimetry is performed through encoding the degree and angle of linear polarization of the incoming light in a sinusoidal modulation of the spectrum. Measuring this intensity spectrum thus provides the spectral dependence of the degree and angle of linear polarization. Polarimetry has proven to be an excellent tool to study microphysical properties of atmospheric particles. Such information is essential to better understand the weather and climate of a planet. Although SPEX can be used to study any planetary atmosphere, including the Earth's, the current design of SPEX is tailored to study Martian dust and clouds from an orbiting platform. SPEX' 9 entrance pupils can simultaneously measure intensity spectra from 0.4 to 0.8 microns, in different directions along the flight direction (including two limb viewing directions). This way, the scattering phase functions of dust and cloud particles within a ground pixel are sampled while flying over it. SPEX can provide synergy with instruments on rovers and landers, as it provides an overview of spatial and temporal variations of the Martian atmosphere.

Study on mathematical model to predict aerated power consumption in a gas-liquid stirred tank

NASA Astrophysics Data System (ADS)

Luan, Deyu; Zhang, Shengfeng; Wei, Xing; Chen, Yiming

The aerated power consumption characteristics in a transparent tank with diameter of 0.3 m and flat bottom stirred by a Rushton impeller were investigated by means of experimental measurement. The test fluid used was tap water as liquid and air as gas. Based on Weibull model, the complete correlation of aerated power with aerated flow number was established through non-linear fit analysis. The effects of aerated rate and impeller speed on aerated power consumption were made an exploration. Results show that the changeable trend of the aerated power consumption is found to be similar under different impeller speeds and impeller diameters, i.e. the aerated power is close to dropping linear at the beginning of gas input, and then the drop tendency decreases as the aerated rate increases, at the end, the aerated power is a constant on the whole as the aerated rate reaches up the loading state. The non-linear fit curve is done using the software Origin based on the experimental data. The fairly high precision of data fit is obtained, which indicates that the mathematical model established can be used to accurately predict the aerated power consumption, comparatively. The proposed research provides a valuable instruction and reference for the design and enlargement of stirred vessel.

Basic research and data analysis for the earth and ocean physics applications program and for the National Geodetic Satellite Program

NASA Technical Reports Server (NTRS)

1976-01-01

Data analysis and supporting research in connection with the following objectives are discussed: (1) provide a precise and accurate geometric description of the earth's surface, (2) provide a precise and accurate mathematical description of the earth's gravitational field, and (3) determine time variations of the geometry of the ocean surface, the solid earth, the gravity field and other geophysical parameters.

Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

NASA Astrophysics Data System (ADS)

Rehak, M.; Skaloud, J.

2015-08-01

In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.

Advanced bioanalytics for precision medicine.

PubMed

Roda, Aldo; Michelini, Elisa; Caliceti, Cristiana; Guardigli, Massimo; Mirasoli, Mara; Simoni, Patrizia

2018-01-01

Precision medicine is a new paradigm that combines diagnostic, imaging, and analytical tools to produce accurate diagnoses and therapeutic interventions tailored to the individual patient. This approach stands in contrast to the traditional "one size fits all" concept, according to which researchers develop disease treatments and preventions for an "average" patient without considering individual differences. The "one size fits all" concept has led to many ineffective or inappropriate treatments, especially for pathologies such as Alzheimer's disease and cancer. Now, precision medicine is receiving massive funding in many countries, thanks to its social and economic potential in terms of improved disease prevention, diagnosis, and therapy. Bioanalytical chemistry is critical to precision medicine. This is because identifying an appropriate tailored therapy requires researchers to collect and analyze information on each patient's specific molecular biomarkers (e.g., proteins, nucleic acids, and metabolites). In other words, precision diagnostics is not possible without precise bioanalytical chemistry. This Trend article highlights some of the most recent advances, including massive analysis of multilayer omics, and new imaging technique applications suitable for implementing precision medicine. Graphical abstract Precision medicine combines bioanalytical chemistry, molecular diagnostics, and imaging tools for performing accurate diagnoses and selecting optimal therapies for each patient.

A novel high sensitivity HPLC assay for topiramate, using 4-chloro-7-nitrobenzofurazan as pre-column fluorescence derivatizing agent.

PubMed

Bahrami, Gholamreza; Mohammadi, Bahareh

2007-05-01

A new, sensitive and simple high-performance liquid chromatographic method for analysis of topiramate, an antiepileptic agent, using 4-chloro-7-nitrobenzofurazan as pre-column derivatization agent is described. Following liquid-liquid extraction of topiramate and an internal standard (amlodipine) from human serum, derivatization of the drugs was performed by the labeling agent in the presence of dichloromethane, methanol, acetonitrile and borate buffer (0.05 M; pH 10.6). A mixture of sodium phosphate buffer (0.05 M; pH 2.4): methanol (35:65 v/v) was eluted as mobile phase and chromatographic separation was achieved using a Shimpack CLC-C18 (150 x 4.6 mm) column. In this method the limit of quantification of 0.01 microg/mL was obtained and the procedure was validated over the concentration range of 0.01 to 12.8 microg/mL. No interferences were found from commonly co-administrated antiepileptic drugs including phenytoin, phenobarbital carbamazepine, lamotrigine, zonisamide, primidone, gabapentin, vigabatrin, and ethosuximide. The analysis performance was carried-out in terms of specificity, sensitivity, linearity, precision, accuracy and stability and the method was shown to be accurate, with intra-day and inter-day accuracy from -3.4 to 10% and precise, with intra-day and inter-day precision from 1.1 to 18%.

Performance evaluation of the microINR® point-of-care INR-testing system.

PubMed

Joubert, J; van Zyl, M C; Raubenheimer, J

2018-04-01

Point-of-care International Normalised Ratio (INR) testing is used frequently. We evaluated the microINR ® POC system for accuracy, precision and measurement repeatability, and investigated instrument and test chip variability and error rates. Venous blood INRs of 210 patients on warfarin were obtained with Thromborel ® S on the Sysmex CS-2100i ® analyser and compared with capillary blood microINR ® values. Precision was assessed using control materials. Measurement repeatability was calculated on 51 duplicate finger-prick INRs. Triplicate finger-prick INRs using three different instruments (30 patients) and three different test chip lots (29 patients) were used to evaluate instrument and test chip variability. Linear regression analysis of microINR ® and Sysmex CS2100i ® values showed a correlation coefficient of 0.96 (P < .0001) and a positive proportional bias of 4.4%. Dosage concordance was 93.8% and clinical agreement 95.7%. All acceptance criteria based on ISO standard 17593:2007 system accuracy requirements were met. Control material coefficients of variation (CV) varied from 6.2% to 16.7%. The capillary blood measurement repeatability CV was 7.5%. No significant instrument (P = .93) or test chip (P = .81) variability was found, and the error rate was low (2.8%). The microINR ® instrument is accurate and precise for monitoring warfarin therapy. © 2017 John Wiley & Sons Ltd.

High-precision dosimetry for radiotherapy using the optically stimulated luminescence technique and thin Al2O3:C dosimeters.

PubMed

Yukihara, E G; Yoshimura, E M; Lindstrom, T D; Ahmad, S; Taylor, K K; Mardirossian, G

2005-12-07

The potential of using the optically stimulated luminescence (OSL) technique with aluminium oxide (Al(2)O(3):C) dosimeters for a precise and accurate estimation of absorbed doses delivered by high-energy photon beams was investigated. This study demonstrates the high reproducibility of the OSL measurements and presents a preliminary determination of the depth-dose curve in water for a 6 MV photon beam from a linear accelerator. The uncertainty of a single OSL measurement, estimated from the variance of a large sample of dosimeters irradiated with the same dose, was 0.7%. In the depth-dose curve obtained using the OSL technique, the difference between the measured and expected doses was < or =0.7% for depths between 1.5 and 10 cm, and 1.1% for a depth of 15 cm. The readout procedure includes a normalization of the response of the dosimeter with respect to a reference dose in order to eliminate variations in the dosimeter mass, dosimeter sensitivity, and the reader's sensitivity. This may be relevant for quality assurance programmes, since it simplifies the requirements in terms of personnel training to achieve the precision and accuracy necessary for radiotherapy applications. We concluded that the OSL technique has the potential to be reliably incorporated in quality assurance programmes and dose verification.

The development of a high-throughput measurement method of octanol/water distribution coefficient based on hollow fiber membrane solvent microextraction technique.

PubMed

Bao, James J; Liu, Xiaojing; Zhang, Yong; Li, Youxin

2014-09-15

This paper describes the development of a novel high-throughput hollow fiber membrane solvent microextraction technique for the simultaneous measurement of the octanol/water distribution coefficient (logD) for organic compounds such as drugs. The method is based on a designed system, which consists of a 96-well plate modified with 96 hollow fiber membrane tubes and a matching lid with 96 center holes and 96 side holes distributing in 96 grids. Each center hole was glued with a sealed on one end hollow fiber membrane tube, which is used to separate the aqueous phase from the octanol phase. A needle, such as microsyringe or automatic sampler, can be directly inserted into the membrane tube to deposit octanol as the accepted phase or take out the mixture of the octanol and the drug. Each side hole is filled with aqueous phase and could freely take in/out solvent as the donor phase from the outside of the hollow fiber membranes. The logD can be calculated by measuring the drug concentration in each phase after extraction equilibrium. After a comprehensive comparison, the polytetrafluoroethylene hollow fiber with the thickness of 210 μm, an extraction time of 300 min, a temperature of 25 °C and atmospheric pressure without stirring are selected for the high throughput measurement. The correlation coefficient of the linear fit of the logD values of five drugs determined by our system to reference values is 0.9954, showed a nice accurate. The -8.9% intra-day and -4.4% inter-day precision of logD for metronidazole indicates a good precision. In addition, the logD values of eight drugs were simultaneously and successfully measured, which indicated that the 96 throughput measure method of logD value was accurate, precise, reliable and useful for high throughput screening. Copyright © 2014 Elsevier B.V. All rights reserved.

Precision measurements of linear scattering density using muon tomography

NASA Astrophysics Data System (ADS)

Åström, E.; Bonomi, G.; Calliari, I.; Calvini, P.; Checchia, P.; Donzella, A.; Faraci, E.; Forsberg, F.; Gonella, F.; Hu, X.; Klinger, J.; Sundqvist Ökvist, L.; Pagano, D.; Rigoni, A.; Ramous, E.; Urbani, M.; Vanini, S.; Zenoni, A.; Zumerle, G.

2016-07-01

We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.

Weighted linear least squares estimation of diffusion MRI parameters: strengths, limitations, and pitfalls.

PubMed

Veraart, Jelle; Sijbers, Jan; Sunaert, Stefan; Leemans, Alexander; Jeurissen, Ben

2013-11-01

Linear least squares estimators are widely used in diffusion MRI for the estimation of diffusion parameters. Although adding proper weights is necessary to increase the precision of these linear estimators, there is no consensus on how to practically define them. In this study, the impact of the commonly used weighting strategies on the accuracy and precision of linear diffusion parameter estimators is evaluated and compared with the nonlinear least squares estimation approach. Simulation and real data experiments were done to study the performance of the weighted linear least squares estimators with weights defined by (a) the squares of the respective noisy diffusion-weighted signals; and (b) the squares of the predicted signals, which are reconstructed from a previous estimate of the diffusion model parameters. The negative effect of weighting strategy (a) on the accuracy of the estimator was surprisingly high. Multi-step weighting strategies yield better performance and, in some cases, even outperformed the nonlinear least squares estimator. If proper weighting strategies are applied, the weighted linear least squares approach shows high performance characteristics in terms of accuracy/precision and may even be preferred over nonlinear estimation methods. Copyright © 2013 Elsevier Inc. All rights reserved.

Gaussian signal relaxation around spin echoes: Implications for precise reversible transverse relaxation quantification of pulmonary tissue at 1.5 and 3 Tesla.

PubMed

Zapp, Jascha; Domsch, Sebastian; Weingärtner, Sebastian; Schad, Lothar R

2017-05-01

To characterize the reversible transverse relaxation in pulmonary tissue and to study the benefit of a quadratic exponential (Gaussian) model over the commonly used linear exponential model for increased quantification precision. A point-resolved spectroscopy sequence was used for comprehensive sampling of the relaxation around spin echoes. Measurements were performed in an ex vivo tissue sample and in healthy volunteers at 1.5 Tesla (T) and 3 T. The goodness of fit using χred2 and the precision of the fitted relaxation time by means of its confidence interval were compared between the two relaxation models. The Gaussian model provides enhanced descriptions of pulmonary relaxation with lower χred2 by average factors of 4 ex vivo and 3 in volunteers. The Gaussian model indicates higher sensitivity to tissue structure alteration with increased precision of reversible transverse relaxation time measurements also by average factors of 4 ex vivo and 3 in volunteers. The mean relaxation times of the Gaussian model in volunteers are T2,G' = (1.97 ± 0.27) msec at 1.5 T and T2,G' = (0.83 ± 0.21) msec at 3 T. Pulmonary signal relaxation was found to be accurately modeled as Gaussian, providing a potential biomarker T2,G' with high sensitivity. Magn Reson Med 77:1938-1945, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Quantitative method for the determination of Iso-fludelone (KOS-1803) in human plasma by LC-MS/MS

PubMed Central

Christner, Susan M.; Parise, Robert A.; Levine, Erica D.; Rizvi, Naiyer A.; Gounder, Mrinal M.; Beumer, Jan H.

2014-01-01

Epothilones are relatively new tubulin-poison anticancer drugs. Iso-fludelone (KOS-1803) is a synthetic third generation epothilone drug discovered at Memorial Sloan Kettering Cancer Center, and currently in Phase I clinical trials. We report an LC-MS/MS assay for the sensitive, accurate and precise quantitation of Iso-fludelone in 0.2 mL of human plasma. Validation was performed according to FDA guidance. The assay comprised of KOS-1724 as the internal standard and an MTBE liquid-liquid extraction with a water wash step. Separation was achieved with an YMC-Pack ODS-AQ column and an isocratic mobile phase of 0.1% formic acid in acetonitrile and water (70:30, v/v) at 0.3 mL/min for 4 min. Chromatographic separation was followed by electrospray, positive-mode ionization tandem mass spectrometric detection in the multiple reaction monitoring (MRM) mode. The assay was linear from 0.1– 300 ng/mL and was accurate (−9.41–7.07%) and precise (1.03–13.7%) which fulfilled FDA criteria for validation. Recovery from plasma was 73.9–79.7% and ion suppression was negligible (−22.8 to −31.3%). Plasma freeze thaw stability (99.97–105.7%), stability for 11 months at −80 °C (94.93–107.9%), and stability for 6 h at room temperature (94.75–105.5%) were all acceptable. This assay is currently being applied to quantitate Iso-fludelone in clinical samples. PMID:25168219

Quantitative method for the determination of iso-fludelone (KOS-1803) in human plasma by LC-MS/MS.

PubMed

Christner, Susan M; Parise, Robert A; Levine, Erica D; Rizvi, Naiyer A; Gounder, Mrinal M; Beumer, Jan H

2014-11-01

Epothilones are relatively new tubulin-poison anticancer drugs. Iso-fludelone (KOS-1803) is a synthetic third generation epothilone drug discovered at Memorial Sloan Kettering Cancer Center, and currently in phase I clinical trials. We report an LC-MS/MS assay for the sensitive, accurate and precise quantitation of iso-fludelone in 0.2mL of human plasma. Validation was performed according to FDA guidance. The assay comprised of KOS-1724 as the internal standard and an MTBE liquid-liquid extraction with a water wash step. Separation was achieved with an YMC-Pack ODS-AQ column and an isocratic mobile phase of 0.1% formic acid in acetonitrile and water (70:30, v/v) at 0.3mL/min for 4min. Chromatographic separation was followed by electrospray, positive-mode ionization tandem mass spectrometric detection in the multiple reaction monitoring (MRM) mode. The assay was linear from 0.1 to 300ng/mL and was accurate (-9.41 to -7.07%) and precise (1.03-13.7%) which fulfilled FDA criteria for validation. Recovery from plasma was 73.9-79.7% and ion suppression was negligible (-22.8 to -31.3%). Plasma freeze-thaw stability (99.97-105.7%), stability for 11 months at -80°C (94.93-107.9%), and stability for 6h at room temperature (94.75-105.5%) were all acceptable. This assay is currently being applied to quantitate iso-fludelone in clinical samples. Copyright © 2014 Elsevier B.V. All rights reserved.

A methodology based on reduced complexity algorithm for system applications using microprocessors

NASA Technical Reports Server (NTRS)

Yan, T. Y.; Yao, K.

1988-01-01

The paper considers a methodology on the analysis and design of a minimum mean-square error criterion linear system incorporating a tapped delay line (TDL) where all the full-precision multiplications in the TDL are constrained to be powers of two. A linear equalizer based on the dispersive and additive noise channel is presented. This microprocessor implementation with optimized power of two TDL coefficients achieves a system performance comparable to the optimum linear equalization with full-precision multiplications for an input data rate of 300 baud.

Accurate GM atrophy quantification in MS using lesion-filling with co-registered 2D lesion masks☆

PubMed Central

Popescu, V.; Ran, N.C.G.; Barkhof, F.; Chard, D.T.; Wheeler-Kingshott, C.A.; Vrenken, H.

2014-01-01

Background In multiple sclerosis (MS), brain atrophy quantification is affected by white matter lesions. LEAP and FSL-lesion_filling, replace lesion voxels with white matter intensities; however, they require precise lesion identification on 3DT1-images. Aim To determine whether 2DT2 lesion masks co-registered to 3DT1 images, yield grey and white matter volumes comparable to precise lesion masks. Methods 2DT2 lesion masks were linearly co-registered to 20 3DT1-images of MS patients, with nearest-neighbor (NNI), and tri-linear interpolation. As gold-standard, lesion masks were manually outlined on 3DT1-images. LEAP and FSL-lesion_filling were applied with each lesion mask. Grey (GM) and white matter (WM) volumes were quantified with FSL-FAST, and deep gray matter (DGM) volumes using FSL-FIRST. Volumes were compared between lesion mask types using paired Wilcoxon tests. Results Lesion-filling with gold-standard lesion masks compared to native images reduced GM overestimation by 1.93 mL (p < .001) for LEAP, and 1.21 mL (p = .002) for FSL-lesion_filling. Similar effects were achieved with NNI lesion masks from 2DT2. Global WM underestimation was not significantly influenced. GM and WM volumes from NNI, did not differ significantly from gold-standard. GM segmentation differed between lesion masks in the lesion area, and also elsewhere. Using the gold-standard, FSL-FAST quantified as GM on average 0.4% of the lesion area with LEAP and 24.5% with FSL-lesion_filling. Lesion-filling did not influence DGM volumes from FSL-FIRST. Discussion These results demonstrate that for global GM volumetry, precise lesion masks on 3DT1 images can be replaced by co-registered 2DT2 lesion masks. This makes lesion-filling a feasible method for GM atrophy measurements in MS. PMID:24567908

Complexity in estimation of esomeprazole and its related impurities' stability in various stress conditions in low-dose aspirin and esomeprazole magnesium capsules.

PubMed

Reddy, Palavai Sripal; Hotha, Kishore Kumar; Sait, Shakil

2013-01-01

A complex, sensitive, and precise high-performance liquid chromatographic method for the profiling of impurities of esomeprazole in low-dose aspirin and esomeprazole capsules has been developed, validated, and used for the determination of impurities in pharmaceutical products. Esomeprazole and its related impurities' development in the presence of aspirin was traditionally difficult due to aspirin's sensitivity to basic conditions and esomeprazole's sensitivity to acidic conditions. When aspirin is under basic, humid, and extreme temperature conditions, it produces salicylic acid and acetic acid moieties. These two byproducts create an acidic environment for the esomeprazole. Due to the volatility and migration phenomenon of the produced acetic acid and salicylic acid from aspirin in the capsule dosage form, esomeprazole's purity, stability, and quantification are affected. The objective of the present research work was to develop a gradient reversed-phase liquid chromatographic method to separate all the degradation products and process-related impurities from the main peak. The impurities were well-separated on a RP8 column (150 mm × 4.6mm, X-terra, RP8, 3.5μm) by the gradient program using a glycine buffer (0.08 M, pH adjusted to 9.0 with 50% NaOH), acetonitrile, and methanol at a flow rate of 1.0 mL min(-1) with detection wavelength at 305 nm and column temperature at 30°C. The developed method was found to be specific, precise, linear, accurate, rugged, and robust. LOQ values for all of the known impurities were below reporting thresholds. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation in the presence of aspirin. The developed RP-HPLC method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, ruggedness, and robustness.

Development of a Stability-Indicating Stereoselective Method for Quantification of the Enantiomer in the Drug Substance and Pharmaceutical Dosage Form of Rosuvastatin Calcium by an Enhanced Approach

PubMed Central

Rajendra Reddy, Gangireddy; Ravindra Reddy, Papammagari; Siva Jyothi, Polisetty

2015-01-01

A novel, simple, precise, and stability-indicating stereoselective method was developed and validated for the accurate quantification of the enantiomer in the drug substance and pharmaceutical dosage forms of Rosuvastatin Calcium. The method is capable of quantifying the enantiomer in the presence of other related substances. The chromatographic separation was achieved with an immobilized cellulose stationary phase (Chiralpak IB) 250 mm x 4.6 mm x 5.0 μm particle size column with a mobile phase containing a mixture of n-hexane, dichloromethane, 2-propanol, and trifluoroacetic acid in the ratio 82:10:8:0.2 (v/v/v/v). The eluted compounds were monitored at 243 nm and the run time was 18 min. Multivariate analysis and statistical tools were used to develop this highly robust method in a short span of time. The stability-indicating power of the method was established by subjecting Rosuvastatin Calcium to the stress conditions (forced degradation) of acid, base, oxidative, thermal, humidity, and photolytic degradation. Major degradation products were identified and found to be well-resolved from the enantiomer peak, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection and limit of quantification, precision, linearity, accuracy, and robustness. The method exhibited consistent, high-quality recoveries (100 ± 10%) with a high precision for the enantiomer. Linear regression analysis revealed an excellent correlation between the peak responses and concentrations (r2 value of 0.9977) for the enantiomer. The method is sensitive enough to quantify the enantiomer above 0.04% and detect the enantiomer above 0.015% in Rosuvastatin Calcium. The stability tests were also performed on the drug substances as per ICH norms. PMID:26839815

DETERMINATION OF AZOXYSTROBIN AND DIFENOCONAZOLE IN PESTICIDE PRODUCTS.

PubMed

Lazić, S; Šunjka, D

2015-01-01

In this study a high performance liquid chromatographic (HPLC-DAD) procedure has been developed for the simultaneous determination of azoxystrobin and difenoconazole in suspension concentrate pesticide formulations, with the aim of the product quality control. Azoxystrobin, strobilurin fungicide and difenoconazole (cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether), triazole fungicide, are used for the protection of plants from wide spectrum of fungal diseases. For the analysis LC system an Agilent Technologies 1100 Series was used. Good separation was achieved on a Zorbax SB-C18 column (5 μm, 250 mm x 3 mm internal diameter) using a mobile phase consisting of acetonitrile/ultrapure water (90:10, v/v), at a flow rate of 0.9 ml/minute and UV detection at 218 nm. Column temperature was 25 degrees C, injected volume was 1 μl. Retention times for azoxystrobin and difenoconazole were 2.504 min and 1.963 min, respectively. This method is validated according to the requirements for new methods, which include linearity, precision, accuracy and selectivity. The method demonstrates good linearity with r2 > 0.997. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 1.9% for azoxystrobin and 0.5% for difenoconazole. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSD) was lower than the RSD calculated using the Horwitz equation of 1.7% and 1.4% for azoxystrobin and difenoconazole, respectively. The accuracy of the proposed method was determined from recovery experiments through standard addition procedure. The average recoveries of the three fortification levels were 101.9% for azoxystrobin and 103.2% for difenoconazole with RSDs of 1.1% and 1.2%. The method described in this paper is simple, precise, accurate and selective and represents a new and reliable way of simultaneous determination of azoxystrobin and difenoconazole in formulated products.

Determination of Bortezomib in API Samples Using HPLC: Assessment of Enantiomeric and Diastereomeric Impurities.

PubMed

Kamalzadeh, Zahra; Babanezhad, Esmaeil; Ghaffari, Solmaz; Mohseni Ezhiyeh, Alireza; Mohammadnejad, Mahdieh; Naghibfar, Mehdi; Bararjanian, Morteza; Attar, Hossein

2017-08-01

A new, normal phase high performance liquid chromatography (NP-HPLC) method was developed for separation of Bortezomib (BZB) enantiomers and quantitative determination of (1S,2R)-enantiomer of BZB in active pharmaceutical ingredient (API) samples. The developed method was validated based on International Conference on Harmonisation (ICH) guidelines and it was proved to be accurate, precise and robust. The obtained resolution (RS) between the enantiomers was more than 2. The calibration curve for (1S,2R)-enantiomer was found to be linear in the concentration range of 0.24-5.36 mg/L with regression coefficient (R2) of 0.9998. Additionally, the limit of detection (LOD) and limit of quantification (LOQ) were 0.052 and 0.16 mg/L, respectively. Also, in this study, a precise, sensitive and robust gradient reversed-phase HPLC (RP-HPLC) method was developed and validated for determination of BZB in API samples. The detector response was linear over the concentration range of 0.26-1110.5 mg/L. The values of R2, LOD and LOQ were 0.9999, 0.084 and 0.25 mg/L, respectively. For both NP-HPLC and RP-HPLC methods, all of the RSD (%) values obtained in the precision study were <1.0%. System suitability parameters in terms of tailing factor (TF), number of theoretical plates (N) and RS were TF < 2.0, N > 2,000 and RS > 2.0. The performance of two common integration methods of valley to valley and drop perpendicular for drawing the baseline between two adjacent peaks were investigated for the determination of diastereomeric impurity (Imp-D) in the BZB-API samples. The results showed that the valley to valley method outperform the drop perpendicular method for calculation of Imp-D peak areas. Therefore, valley to valley method was chosen for peak integration. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Method development for the determination of fluorine in water samples via the molecular absorption of strontium monofluoride formed in an electrothermal atomizer

NASA Astrophysics Data System (ADS)

Ozbek, Nil; Akman, Suleyman

The presence of fluorine (F) was detected via the rotational molecular absorption line of diatomic strontium-monofluoride (SrF) generated in the gas phase at 651.187 nm using high-resolution continuum source electrothermal atomic absorption spectrometry. Upon the addition of excess strontium (Sr) as the nitrate, the fluorine in the sample was converted to SrF in the gas phase of a graphite furnace. The effects on the accuracy, precision and sensitivity of variables such as the SrF wavelength, graphite furnace program, amount of Sr, coating of the graphite tube and platform with Zr and Ir and the use of a modifier were investigated and optimized. It was determined that there was no need to use a modifier or to cover the platform/tubes with Zr or Ir. Fluorine concentrations in various water samples (certified waste water, tap water, drinking water and mineral water) were determined using 20 μg of Sr as the molecule-forming reagent and applying a maximum pyrolysis temperature of 800 °C and a molecule-forming temperature of 2200 °C with a heating rate of 2000 °C s- 1. Good linearity was maintained up to 0.1 μg of F. The accuracy and precision of the method were tested by analyzing certified reference wastewater. The results were in good agreement with certified values, and the precision was satisfactory (RSD < 10%). The limit of detection and the characteristic mass for the method were 0.36 ng and 0.55 ng, respectively. Finally, the fluorine concentrations in several drinking water and mineral water samples taken from the market were determined. The results were in good agreement with the values supplied by the producers. No significant differences were found between the results from the linear calibration and standard addition techniques. The method was determined to be simple, fast, accurate and sensitive.

High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn.

PubMed

Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

2017-01-01

Sea buckthorn ( Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes ( R 2 > 0.9997). The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically active components in traditional Chinese medicine and its preparation Abbreviation used: PR: protocatechuic acid, RU: rutin, QU: quercetin, KA: kaempferol, IS: isorhamnetin, HPLC: high-performance liquid chromatography, HPLC-DAD: high performance liquid chromatographydiode array detector, LOD: linearity and limit of detection, LOQ: limit of quantitation, RSD: relative standard deviation.

LiF TLD-100 as a Dosimeter in High Energy Proton Beam Therapy-Can It Yield Accurate Results?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zullo, John R.; Kudchadker, Rajat J.; Zhu, X. Ronald

In the region of high-dose gradients at the end of the proton range, the stopping power ratio of the protons undergoes significant changes, allowing for a broad spectrum of proton energies to be deposited within a relatively small volume. Because of the potential linear energy transfer dependence of LiF TLD-100 (thermolumescent dosimeter), dose measurements made in the distal fall-off region of a proton beam may be less accurate than those made in regions of low-dose gradients. The purpose of this study is to determine the accuracy and precision of dose measured using TLD-100 for a pristine Bragg peak, particularly inmore » the distal fall-off region. All measurements were made along the central axis of an unmodulated 200-MeV proton beam from a Probeat passive beam-scattering proton accelerator (Hitachi, Ltd., Tokyo, Japan) at varying depths along the Bragg peak. Measurements were made using TLD-100 powder flat packs, placed in a virtual water slab phantom. The measurements were repeated using a parallel plate ionization chamber. The dose measurements using TLD-100 in a proton beam were accurate to within {+-}5.0% of the expected dose, previously seen in our past photon and electron measurements. The ionization chamber and the TLD relative dose measurements agreed well with each other. Absolute dose measurements using TLD agreed with ionization chamber measurements to within {+-} 3.0 cGy, for an exposure of 100 cGy. In our study, the differences in the dose measured by the ionization chamber and those measured by TLD-100 were minimal, indicating that the accuracy and precision of measurements made in the distal fall-off region of a pristine Bragg peak is within the expected range. Thus, the rapid change in stopping power ratios at the end of the range should not affect such measurements, and TLD-100 may be used with confidence as an in vivo dosimeter for proton beam therapy.« less

A microfluidic thermometer: Precise temperature measurements in microliter- and nanoliter-scale volumes

PubMed Central

McKenzie, Brittney A.

2017-01-01

Measuring the temperature of a sample is a fundamental need in many biological and chemical processes. When the volume of the sample is on the microliter or nanoliter scale (e.g., cells, microorganisms, precious samples, or samples in microfluidic devices), accurate measurement of the sample temperature becomes challenging. In this work, we demonstrate a technique for accurately determining the temperature of microliter volumes using a simple 3D-printed microfluidic chip. We accomplish this by first filling “microfluidic thermometer” channels on the chip with substances with precisely known freezing/melting points. We then use a thermoelectric cooler to create a stable and linear temperature gradient along these channels within a measurement region on the chip. A custom software tool (available as online Supporting Information) is then used to find the locations of solid-liquid interfaces in the thermometer channels; these locations have known temperatures equal to the freezing/melting points of the substances in the channels. The software then uses the locations of these interfaces to calculate the temperature at any desired point within the measurement region. Using this approach, the temperature of any microliter-scale on-chip sample can be measured with an uncertainty of about a quarter of a degree Celsius. As a proof-of-concept, we use this technique to measure the unknown freezing point of a 50 microliter volume of solution and demonstrate its feasibility on a 400 nanoliter sample. Additionally, this technique can be used to measure the temperature of any on-chip sample, not just near-zero-Celsius freezing points. We demonstrate this by using an oil that solidifies near room temperature (coconut oil) in a microfluidic thermometer to measure on-chip temperatures well above zero Celsius. By providing a low-cost and simple way to accurately measure temperatures in small volumes, this technique should find applications in both research and educational laboratories. PMID:29284028

Cross-calibration of liquid and solid QCT calibration standards: corrections to the UCSF normative data

NASA Technical Reports Server (NTRS)

Faulkner, K. G.; Gluer, C. C.; Grampp, S.; Genant, H. K.

1993-01-01

Quantitative computed tomography (QCT) has been shown to be a precise and sensitive method for evaluating spinal bone mineral density (BMD) and skeletal response to aging and therapy. Precise and accurate determination of BMD using QCT requires a calibration standard to compensate for and reduce the effects of beam-hardening artifacts and scanner drift. The first standards were based on dipotassium hydrogen phosphate (K2HPO4) solutions. Recently, several manufacturers have developed stable solid calibration standards based on calcium hydroxyapatite (CHA) in water-equivalent plastic. Due to differences in attenuating properties of the liquid and solid standards, the calibrated BMD values obtained with each system do not agree. In order to compare and interpret the results obtained on both systems, cross-calibration measurements were performed in phantoms and patients using the University of California San Francisco (UCSF) liquid standard and the Image Analysis (IA) solid standard on the UCSF GE 9800 CT scanner. From the phantom measurements, a highly linear relationship was found between the liquid- and solid-calibrated BMD values. No influence on the cross-calibration due to simulated variations in body size or vertebral fat content was seen, though a significant difference in the cross-calibration was observed between scans acquired at 80 and 140 kVp. From the patient measurements, a linear relationship between the liquid (UCSF) and solid (IA) calibrated values was derived for GE 9800 CT scanners at 80 kVp (IA = [1.15 x UCSF] - 7.32).(ABSTRACT TRUNCATED AT 250 WORDS).

Extraction optimization and UHPLC method development for determination of the 20-hydroxyecdysone in Sida tuberculata leaves.

PubMed

da Rosa, Hemerson S; Koetz, Mariana; Santos, Marí Castro; Jandrey, Elisa Helena Farias; Folmer, Vanderlei; Henriques, Amélia Teresinha; Mendez, Andreas Sebastian Loureiro

2018-04-01

Sida tuberculata (ST) is a Malvaceae species widely distributed in Southern Brazil. In traditional medicine, ST has been employed as hypoglycemic, hypocholesterolemic, anti-inflammatory and antimicrobial. Additionally, this species is chemically characterized by flavonoids, alkaloids and phytoecdysteroids mainly. The present work aimed to optimize the extractive technique and to validate an UHPLC method for the determination of 20-hydroxyecdsone (20HE) in the ST leaves. Box-Behnken Design (BBD) was used in method optimization. The extractive methods tested were: static and dynamic maceration, ultrasound, ultra-turrax and reflux. In the Box-Behnken three parameters were evaluated in three levels (-1, 0, +1), particle size, time and plant:solvent ratio. In validation method, the parameters of selectivity, specificity, linearity, limits of detection and quantification (LOD, LOQ), precision, accuracy and robustness were evaluated. The results indicate static maceration as better technique to obtain 20HE peak area in ST extract. The optimal extraction from surface response methodology was achieved with the parameters granulometry of 710 nm, 9 days of maceration and plant:solvent ratio 1:54 (w/v). The UHPLC-PDA analytical developed method showed full viability of performance, proving to be selective, linear, precise, accurate and robust for 20HE detection in ST leaves. The average content of 20HE was 0.56% per dry extract. Thus, the optimization of extractive method in ST leaves increased the concentration of 20HE in crude extract, and a reliable method was successfully developed according to validation requirements and in agreement with current legislation. Copyright © 2018 Elsevier Inc. All rights reserved.

Development of a fast LC-MS/MS assay for the determination of deferiprone in human plasma and application to pharmacokinetics.

PubMed

Song, Ta-Shu; Hsieh, Yow-Wen; Peng, Ching-Tien; Liu, Cheng-Hsiung; Chen, Tai-Lin; Hour, Mann-Jen

2012-12-01

A fast and accurate liquid chromatography/tandem mass spectrometric (LC-MS/MS) assay was first developed and validated for the determination of deferiprone in human plasma. The analytes were extracted with acetonitrile from only 50 μL aliquots of human plasma to achieve the protein precipitation. After extraction, chromatographic separation of analytes in human plasma was performed using a Synergi Fusion-RP 80A column at 30 °C. The mobile phase consisted of methanol and 0.2% formic acid containing 0.2 mM EDTA (60:40, v/v). The flow rate of the mobile phase was 0.8 mL/min. The total run time for each sample analysis was 4 min. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the precursor-to-parent ion transitions m/z 140.1 → 53.1 for deferiprone and m/z 143.1 → 98.1 for internal standard. A linear range was established from 0.1 to 20 µg/mL. The limit of detection was determined as 0.05 µg/mL. The validated method was estimated for linearity, recovery, stability, precision and accuracy. Intraday and interday precisions were 4.3-5.5 and 4.6-7.3%, respectively. The recovery of deferiprone was in the range of 80.1-86.8%. The method was successfully applied to a pharmacokinetic study of deferiprone in six thalassemia patients. Copyright © 2012 John Wiley & Sons, Ltd.

Simultaneous quantification and identification of flavonoids, lignans, coumarin and amides in leaves of Zanthoxylum armatum using UPLC-DAD-ESI-QTOF-MS/MS.

PubMed

Bhatt, Vinod; Sharma, Sushila; Kumar, Neeraj; Sharma, Upendra; Singh, Bikram

2017-01-05

The current study presents isolation and characterization of twelve compounds including catechin (1), isovitexin (2), hesperidin (3), psoralin (4), eudesmin (5), kobusin (6), fargesin (7), sesamin (8), asarinin (9), planispine-A (10), α-sanshool (11) and vitexin (12), from the leaves of Zanthoxylum armatum. Further, two rapid and simple ultra performance liquid chromatography-diode array detection (UPLC-DAD) methods were developed for the simultaneous quantitative determination of isolated compounds from Z. armatum leaves. These analytical methods were validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The LOD and LOQ were in the range of 0.06-0.21μg/mL and 0.19-0.69μg/mL, respectively. The validated method was linear (R 2 ≥0.9906), precise in terms of peak area (intra-day RSDs <3.8% and inter-day RSDs <2.7%), and accurate (109.6-92.5%). This is the first report on the isolation and quantification of 1, 2, 4 and 12 in Z. armatum and 3 in Zanthoxylum genus. The methods: were successfully applied to assess the quality of samples collected from different locations of Himachal Pradesh during summer and winter season. The results demonstrated that flavonoids and furofuran lignans were the major constituents in Z. armatum leaves. The developed methods: were further applied for tandem electrospray ionization-mass spectrometry (UPLC-DAD-ESI-MS/MS) and total eighteen compounds were identified including phenolic acid, flavonoids, furofuran lignans, coumarin and isobutyl amides. Copyright © 2016 Elsevier B.V. All rights reserved.

Traceability Assessment and Performance Evaluation of Results for Measurement of Abbott Clinical Chemistry Assays on 4 Chemistry Analyzers.

PubMed

Lim, Jinsook; Song, Kyung Eun; Song, Sang Hoon; Choi, Hyun-Jung; Koo, Sun Hoe; Kwon, Gye Choel

2016-05-01

-The traceability of clinical results to internationally recognized and accepted reference materials and reference measurement procedures has become increasingly important. Therefore, the establishment of traceability has become a mandatory requirement for all in vitro diagnostics devices. -To evaluate the traceability of the Abbott Architect c8000 system (Abbott Laboratories, Abbott Park, Illinois), consisting of calibrators and reagents, across 4 different chemistry analyzers, and to evaluate its general performance on the Toshiba 2000FR NEO (Toshiba Medical Systems Corporation, Otawara-shi, Tochigi-ken, Japan). -For assessment of traceability, secondary reference materials were evaluated 5 times, and then bias was calculated. Precision, linearity, and carryover were determined according to the guidelines of the Clinical and Laboratory Standards Institute (Wayne, Pennsylvania). -The biases from 4 different analyzers ranged from -2.33% to 2.70% on the Toshiba 2000FR NEO, -2.33% to 5.12% on the Roche Hitachi 7600 (Roche Diagnostics International, Basel, Switzerland), -0.93% to 2.87% on the Roche Modular, and -2.16% to 2.86% on the Abbott Architect c16000. The total coefficients of variance of all analytes were less than 5%. The coefficients of determination (R(2)) were more than 0.9900. The carryover rate ranged from -0.54% to 0.17%. -Abbott clinical chemistry assays met the performance criteria based on desirable biological variation for precision, bias, and total error. They also showed excellent linearity and carryover. Therefore, these clinical chemistry assays were found to be accurate and reliable and are readily applicable on the various platforms used in this study.

Comparison of UV spectrophotometry and high performance liquid chromatography methods for the determination of repaglinide in tablets.

PubMed

Dhole, Seema M; Khedekar, Pramod B; Amnerkar, Nikhil D

2012-07-01

Repaglinide is a miglitinide class of antidiabetic drug used for the treatment of type 2 diabetes mellitus. A fast and reliable method for the determination of repaglinide was highly desirable to support formulation screening and quality control. UV spectrophotometric and reversed-phase high performance liquid chromatography (RP-HPLC) methods were developed for determination of repaglinide in the tablet dosage form. The UV spectrum recorded between 200 400 nm using methanol as solvent and the wavelength 241 nm was selected for the determination of repaglinide. RP-HPLC analysis was carried out using Agilent TC-C18 (2) column and mobile phase composed of methanol and water (80:20 v/v, pH adjusted to 3.5 with orthophosphoric acid) at a flow rate of 1.0 ml/min. Parameters such as linearity, precision, accuracy, recovery, specificity and ruggedness are studied as reported in the International Conference on Harmonization (ICH) guidelines. The developed methods illustrated excellent linearity (r(2) > 0.999) in the concentration range of 5-30 μg/ml and 5-50 μg/ml for UV spectrophotometric and HPLC methods, respectively. Precision (%R.S.D < 1.50) and mean recoveries were found in the range of 99.63-100.45% for UV spectrophotometric method and 99.71-100.25% for HPLC method which shows accuracy of the methods. The developed methods were found to be reliable, simple, fast, accurate and successfully used for the quality control of repaglinide as a bulk drug and in pharmaceutical formulations.

Comparison of UV spectrophotometry and high performance liquid chromatography methods for the determination of repaglinide in tablets

PubMed Central

Dhole, Seema M.; Khedekar, Pramod B.; Amnerkar, Nikhil D.

2012-01-01

Background: Repaglinide is a miglitinide class of antidiabetic drug used for the treatment of type 2 diabetes mellitus. A fast and reliable method for the determination of repaglinide was highly desirable to support formulation screening and quality control. Objective: UV spectrophotometric and reversed-phase high performance liquid chromatography (RP-HPLC) methods were developed for determination of repaglinide in the tablet dosage form. Materials and Methods: The UV spectrum recorded between 200 400 nm using methanol as solvent and the wavelength 241 nm was selected for the determination of repaglinide. RP-HPLC analysis was carried out using Agilent TC-C18 (2) column and mobile phase composed of methanol and water (80:20 v/v, pH adjusted to 3.5 with orthophosphoric acid) at a flow rate of 1.0 ml/min. Parameters such as linearity, precision, accuracy, recovery, specificity and ruggedness are studied as reported in the International Conference on Harmonization (ICH) guidelines. Results: The developed methods illustrated excellent linearity (r2 > 0.999) in the concentration range of 5-30 μg/ml and 5-50 μg/ml for UV spectrophotometric and HPLC methods, respectively. Precision (%R.S.D < 1.50) and mean recoveries were found in the range of 99.63-100.45% for UV spectrophotometric method and 99.71-100.25% for HPLC method which shows accuracy of the methods. Conclusion: The developed methods were found to be reliable, simple, fast, accurate and successfully used for the quality control of repaglinide as a bulk drug and in pharmaceutical formulations. PMID:23781481

Sources of variability in satellite-derived estimates of Phytoplankton production in the eastern tropical Pacific

NASA Astrophysics Data System (ADS)

Banse, Karl; Yong, Marina

1990-05-01

As a proxy for satellite (coastal zone color scanner) observations and concurrent measurements of primary production rates, data from 138 stations occupied seasonally during 1967-1968 in the offshore, eastern tropical Pacific were analyzed in terms of six temporal groups and four current regimes. In multiple linear regressions on column production Pt, we found that simulated satellite pigment is generally weakly correlated, but sometimes not correlated with Pt, and that incident irradiance, sea surface temperature, nitrate, transparency, and depths of mixed layer or nitracline assume little or no importance. After a proxy for the light-saturated chlorophyll-specific photosynthetic rate pmax is added, the coefficient of determination (r2) ranges from 0.55 to 0.91 (median of 0.85) for the 10 cases. In stepwise multiple linear regressions the pmax proxy is the best predictor for Pt. Pt can be calculated fairly accurately (on the average, within 10-20%) from satellite pigment, the 10% light depth, and station values (but not from regional or seasonal means) of the pmax proxy; for individual stations the precision is 35-84% (median of 57% for the 10 groupings; p = 0.05) of the means of observed values. At present, pmax cannot be estimated from space; in the data set it is not even highly correlated with irradiance, temperature, and nitrate at depth of occurrence. Therefore extant models for calculating Pt in this tropical ocean have inherent limits of accuracy as well as of precision owing to ignorance about a physiological parameter.

Precision Interval Estimation of the Response Surface by Means of an Integrated Algorithm of Neural Network and Linear Regression

NASA Technical Reports Server (NTRS)

Lo, Ching F.

1999-01-01

The integration of Radial Basis Function Networks and Back Propagation Neural Networks with the Multiple Linear Regression has been accomplished to map nonlinear response surfaces over a wide range of independent variables in the process of the Modem Design of Experiments. The integrated method is capable to estimate the precision intervals including confidence and predicted intervals. The power of the innovative method has been demonstrated by applying to a set of wind tunnel test data in construction of response surface and estimation of precision interval.

Quantitative determination and validation of octreotide acetate using 1 H-NMR spectroscopy with internal standard method.

PubMed

Yu, Chen; Zhang, Qian; Xu, Peng-Yao; Bai, Yin; Shen, Wen-Bin; Di, Bin; Su, Meng-Xiang

2018-01-01

Quantitative nuclear magnetic resonance (qNMR) is a well-established technique in quantitative analysis. We presented a validated 1 H-qNMR method for assay of octreotide acetate, a kind of cyclic octopeptide. Deuterium oxide was used to remove the undesired exchangeable peaks, which was referred to as proton exchange, in order to make the quantitative signals isolated in the crowded spectrum of the peptide and ensure precise quantitative analysis. Gemcitabine hydrochloride was chosen as the suitable internal standard. Experimental conditions, including relaxation delay time, the numbers of scans, and pulse angle, were optimized first. Then method validation was carried out in terms of selectivity, stability, linearity, precision, and robustness. The assay result was compared with that by means of high performance liquid chromatography, which is provided by Chinese Pharmacopoeia. The statistical F test, Student's t test, and nonparametric test at 95% confidence level indicate that there was no significant difference between these two methods. qNMR is a simple and accurate quantitative tool with no need for specific corresponding reference standards. It has the potential of the quantitative analysis of other peptide drugs and standardization of the corresponding reference standards. Copyright © 2017 John Wiley & Sons, Ltd.

Analytical Kinematics and Coupled Vibrations Analysis of Mechanical System Operated by Solar Array Drive Assembly

NASA Astrophysics Data System (ADS)

Sattar, M.; Wei, C.; Jalali, A.; Sattar, R.

2017-07-01

To address the impact of solar array (SA) anomalies and vibrations on performance of precision space-based operations, it is important to complete its accurate jitter analysis. This work provides mathematical modelling scheme to approximate kinematics and coupled micro disturbance dynamics of rigid load supported and operated by solar array drive assembly (SADA). SADA employed in analysis provides a step wave excitation torque to activate the system. Analytical investigations into kinematics is accomplished by using generalized linear and Euler angle coordinates, applying multi-body dynamics concepts and transformations principles. Theoretical model is extended, to develop equations of motion (EoM), through energy method (Lagrange equation). The main emphasis is to research coupled frequency response by determining energies dissipated and observing dynamic behaviour of internal vibratory systems of SADA. The disturbance model captures discrete active harmonics of SADA, natural modes and vibration amplifications caused by interactions between active harmonics and structural modes of mechanical assembly. The proposed methodology can help to predict true micro disturbance nature of SADA operating rigid load. Moreover, performance outputs may be compared against actual mission requirements to assess precise spacecraft controller design to meet next space generation stringent accuracy goals.

Working towards accreditation by the International Standards Organization 15189 Standard: how to validate an in-house developed method an example of lead determination in whole blood by electrothermal atomic absorption spectrometry.

PubMed

Garcia Hejl, Carine; Ramirez, Jose Manuel; Vest, Philippe; Chianea, Denis; Renard, Christophe

2014-09-01

Laboratories working towards accreditation by the International Standards Organization (ISO) 15189 standard are required to demonstrate the validity of their analytical methods. The different guidelines set by various accreditation organizations make it difficult to provide objective evidence that an in-house method is fit for the intended purpose. Besides, the required performance characteristics tests and acceptance criteria are not always detailed. The laboratory must choose the most suitable validation protocol and set the acceptance criteria. Therefore, we propose a validation protocol to evaluate the performance of an in-house method. As an example, we validated the process for the detection and quantification of lead in whole blood by electrothermal absorption spectrometry. The fundamental parameters tested were, selectivity, calibration model, precision, accuracy (and uncertainty of measurement), contamination, stability of the sample, reference interval, and analytical interference. We have developed a protocol that has been applied successfully to quantify lead in whole blood by electrothermal atomic absorption spectrometry (ETAAS). In particular, our method is selective, linear, accurate, and precise, making it suitable for use in routine diagnostics.

A validated HPLC determination of the flavone aglycone diosmetin in human plasma.

PubMed

Kanaze, Feras Imad; Bounartzi, Melpomeni I; Niopas, Ioannis

2004-12-01

Diosmetin, 3',5,7-trihydroxy-4'-methoxy flavone, is the aglycone of the flavonoid glycoside diosmin that occurs naturally in foods of plant origin. Diosmin exhibits antioxidant and anti-inflammatory activities, improves venous tone and it is used for the treatment of chronic venous insufficiency. Diosmin is hydrolyzed by enzymes of intestinal micro flora before absorption of its aglycone diosmetin. A specific, sensitive, precise, accurate and robust HPLC assay for the determination of diosmetin in human plasma was developed and validated. Diosmetin and the internal standard 7-ethoxycoumarin were isolated from plasma by liquid-liquid extraction and separated on a C8 reversed-phase column with methanol-water-acetic acid (55:43:2, v/v/v) as the mobile phase at 43 degrees C. Peaks were monitored at 344 nm. The method was linear in the 10-300 ng/mL concentration range (r > 0.999). Recovery for diosmetin and internal standard was greater than 89.7 and 86.8%, respectively. Intra-day and inter-day precision for diosmetin ranged from 1.6 to 4.6 and from 2.2 to 5.3%, respectively, and accuracy was better than 97.9%. Copyright 2004 John Wiley & Sons, Ltd.

Development and validation of a high throughput assay for the quantification of multiple green tea-derived catechins in human plasma.

PubMed

Mawson, Deborah H; Jeffrey, Keon L; Teale, Philip; Grace, Philip B

2018-06-19

A rapid, accurate and robust method for the determination of catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (Cg), epicatechin gallate (ECg), gallocatechin gallate (GCg) and epigallocatechin gallate (EGCg) concentrations in human plasma has been developed. The method utilises protein precipitation following enzyme hydrolysis, with chromatographic separation and detection using reversed-phase liquid chromatography - tandem mass spectrometry (LC-MS/MS). Traditional issues such as lengthy chromatographic run times, sample and extract stability, and lack of suitable internal standards have been addressed. The method has been evaluated using a comprehensive validation procedure, confirming linearity over appropriate concentration ranges, and inter/intra batch precision and accuracies within suitable thresholds (precisions within 13.8% and accuracies within 12.4%). Recoveries of analytes were found to be consistent between different matrix samples, compensated for using suitable internal markers and within the performance of the instrumentation used. Similarly, chromatographic interferences have been corrected using the internal markers selected. Stability of all analytes in matrix is demonstrated over 32 days and throughout extraction conditions. This method is suitable for high throughput sample analysis studies. This article is protected by copyright. All rights reserved.

Leaner and greener analysis of cannabinoids.

PubMed

Mudge, Elizabeth M; Murch, Susan J; Brown, Paula N

2017-05-01

There is an explosion in the number of labs analyzing cannabinoids in marijuana (Cannabis sativa L., Cannabaceae) but existing methods are inefficient, require expert analysts, and use large volumes of potentially environmentally damaging solvents. The objective of this work was to develop and validate an accurate method for analyzing cannabinoids in cannabis raw materials and finished products that is more efficient and uses fewer toxic solvents. An HPLC-DAD method was developed for eight cannabinoids in cannabis flowers and oils using a statistically guided optimization plan based on the principles of green chemistry. A single-laboratory validation determined the linearity, selectivity, accuracy, repeatability, intermediate precision, limit of detection, and limit of quantitation of the method. Amounts of individual cannabinoids above the limit of quantitation in the flowers ranged from 0.02 to 14.9% w/w, with repeatability ranging from 0.78 to 10.08% relative standard deviation. The intermediate precision determined using HorRat ratios ranged from 0.3 to 2.0. The LOQs for individual cannabinoids in flowers ranged from 0.02 to 0.17% w/w. This is a significant improvement over previous methods and is suitable for a wide range of applications including regulatory compliance, clinical studies, direct patient medical services, and commercial suppliers.

Smart manipulation of ratio spectra for resolving a pharmaceutical mixture of Methocarbamol and Paracetamol

NASA Astrophysics Data System (ADS)

Essam, Hebatallah M.; Abd-El Rahman, Mohamed K.

2015-04-01

Two smart, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for simultaneous determination of Methocarbamol (METH) and Paracetamol (PAR) in their combined pharmaceutical formulation without preliminary separation. Method A, is an extended ratio subtraction one (EXRSM) coupled with ratio subtraction method (RSM), which depends on subtraction of the plateau values from the ratio spectrum. Method B is a ratio difference spectrophotometric one (RDM) which measures the difference in amplitudes of ratio spectra between 278 and 286 nm for METH and 247 and 260 nm for PAR. The calibration curves are linear over the concentration range of 10-100 μg mL-1 and 2-20 μg mL-1 for METH and PAR, respectively. The specificity of the developed methods was investigated by analyzing different laboratory prepared mixtures of the two drugs. Both methods were applied successfully for the determination of the selected drugs in their combined dosage form. Furthermore, validation was performed according to ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Statistical studies showed that both methods can be competitively applied in quality control laboratories.

Validation of four different spectrophotometric methods for simultaneous determination of Domperidone and Ranitidine in bulk and pharmaceutical formulation.

PubMed

Abdel-Ghany, Maha F; Abdel-Aziz, Omar; Mohammed, Yomna Y

2015-01-01

Four simple, specific, accurate and precise spectrophotometric methods were developed and validated for simultaneous determination of Domperidone (DP) and Ranitidine Hydrochloride (RT) in bulk powder and pharmaceutical formulation. The first method was simultaneous ratio subtraction (SRS), the second was ratio subtraction (RS) coupled with zero order spectrophotometry (D(0)), the third was first derivative of the ratio spectra ((1)DD) and the fourth method was mean centering of ratio spectra (MCR). The calibration curve is linear over the concentration range of 0.5-5 and 1-45 μg mL(-1) for DP and RT, respectively. The proposed spectrophotometric methods can analyze both drugs without any prior separation steps. The selectivity of the adopted methods was tested by analyzing synthetic mixtures of the investigated drugs, also in their pharmaceutical formulation. The suggested methods were validated according to International Conference of Harmonization (ICH) guidelines and the results revealed that; they were precise and reproducible. All the obtained results were statistically compared with those of the reported method, where there was no significant difference. Copyright © 2015 Elsevier B.V. All rights reserved.

Development and validation of RP HPLC method to determine nandrolone phenylpropionate in different pharmaceutical formulations.

PubMed

Mukherjee, Jayanti; Das, Ayan; Chakrabarty, Uday Sankar; Sahoo, Bijay Kumar; Dey, Goutam; Choudhury, Hira; Pal, Tapan Kumar

2011-01-01

This study describes development and subsequent validation of a reversed phase high performance liquid chromatographic (RP-HPLC) method for the estimation of nandrolone phenylpropionate, an anabolic steroid, in bulk drug, in conventional parenteral dosage formulation and in prepared nanoparticle dosage form. The chromatographic system consisted of a Luna Phenomenex, CN (250 mm x 4.6 mm, 5 microm) column, an isocratic mobile phase comprising 10 mM phosphate buffer and acetonitrile (50:50, v/v) and UV detection at 240 nm. Nandrolone phenylpropionate was eluted about 6.3 min with no interfering peaks of excipients used for the preparation of dosage forms. The method was linear over the range from 0.050 to 25 microg/mL in raw drug (r2 = 0.9994). The intra-day and inter-day precision values were in the range of 0.219-0.609% and 0.441-0.875%, respectively. Limits of detection and quantitation were 0.010 microg/mL and 0.050 microg/mL, respectively. The results were validated according to International Conference on Harmonization (ICH) guidelines in parenteral and prepared nanoparticle formulation. The validated HPLC method is simple, sensitive, precise, accurate and reproducible.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolme, David S; Mikkilineni, Aravind K; Rose, Derek C

Analog computational circuits have been demonstrated to provide substantial improvements in power and speed relative to digital circuits, especially for applications requiring extreme parallelism but only modest precision. Deep machine learning is one such area and stands to benefit greatly from analog and mixed-signal implementations. However, even at modest precisions, offsets and non-linearity can degrade system performance. Furthermore, in all but the simplest systems, it is impossible to directly measure the intermediate outputs of all sub-circuits. The result is that circuit designers are unable to accurately evaluate the non-idealities of computational circuits in-situ and are therefore unable to fully utilizemore » measurement results to improve future designs. In this paper we present a technique to use deep learning frameworks to model physical systems. Recently developed libraries like TensorFlow make it possible to use back propagation to learn parameters in the context of modeling circuit behavior. Offsets and scaling errors can be discovered even for sub-circuits that are deeply embedded in a computational system and not directly observable. The learned parameters can be used to refine simulation methods or to identify appropriate compensation strategies. We demonstrate the framework using a mixed-signal convolution operator as an example circuit.« less

A Wide Linearity Range Method for the Determination of Lenalidomide in Plasma by High-Performance Liquid Chromatography: Application to Pharmacokinetic Studies.

PubMed

Guglieri-López, Beatriz; Pérez-Pitarch, Alejandro; Martinez-Gómez, Maria Amparo; Porta-Oltra, Begoña; Climente-Martí, Mónica; Merino-Sanjuán, Matilde

2016-12-01

A wide linearity range analytical method for the determination of lenalidomide in patients with multiple myeloma for pharmacokinetic studies is required. Plasma samples were ultrasonicated for protein precipitation. A solid-phase extraction was performed. The eluted samples were evaporated to dryness under vacuum, and the solid obtained was diluted and injected into the high-performance liquid chromatography (HPLC) system. Separation of lenalidomide was performed on an Xterra RP C18 (250 mm length × 4.6 mm i.d., 5 µm) using a mobile phase consisting of phosphate buffer/acetonitrile (85:15, v/v, pH 3.2) at a flow rate of 0.5 mL · min -1 The samples were monitored at a wavelength of 311 nm. A linear relationship with good correlation coefficient (r = 0.997, n = 9) was found between the peak area and lenalidomide concentrations in the range of 100 to 950 ng · mL -1 The limits of detection and quantitation were 28 and 100 ng · mL -1 , respectively. The intra- and interassay precisions were satisfactory, and the accuracy of the method was proved. In conclusion, the proposed method is suitable for the accurate quantification of lenalidomide in human plasma with a wide linear range, from 100 to 950 ng · mL -1 This is a valuable method for pharmacokinetic studies of lenalidomide in human subjects. © 2016 Society for Laboratory Automation and Screening.

Basic research and data analysis for the National Geodetic Satellite Program and for the Earth and Ocean Physics Application Program

NASA Technical Reports Server (NTRS)

1974-01-01

Accomplishments in the continuing programs are reported. The data were obtained in support of the following broad objectives: (1) to provide a precise and accurate geometric description of the earth's surface; (2) to provide a precise and accurate mathematical description of the earth's gravitational field; and (3) to determine time variations of the geometry of the ocean surface, the solid earth, the gravity field, and other geophysical parameters.

Measurement of LHCD antenna position in Aditya tokamak

NASA Astrophysics Data System (ADS)

Ambulkar, K. K.; Sharma, P. K.; Virani, C. G.; Parmar, P. R.; Thakur, A. L.; Kulkarni, S. V.

2010-02-01

To drive plasma current non-inductively in ADITYA tokamak, 120 kW pulsed Lower Hybrid Current Drive (LHCD) system at 3.7 GHz has been designed, fabricated and installed on ADITYA tokamak. In this system, the antenna consists of a grill structure, having two rows, each row comprising of four sub-waveguides. The coupling of LHCD power to the plasma strongly depends on the plasma density near the mouth of grill antenna. Thus the grill antenna has to be precisely positioned for efficient coupling. The movement of mechanical bellow, which contracts or expands up to 50mm, governs the movement of antenna. In order to monitor the position of the antenna precisely, the reference position of the antenna with respect to the machine/plasma position has to be accurately determined. Further a mechanical system or an electronic system to measure the relative movement of the antenna with respect to the reference position is also desired. Also due to poor accessibility inside the ADITYA machine, it is impossible to measure physically the reference position of the grill antenna with respect to machine wall, taken as reference position and hence an alternative method has to be adopted to establish these measurements reliably. In this paper we report the design and development of a mechanism, using which the antenna position measurements are made. It also describes a unique method employing which the measurements of the reference position of the antenna with respect to the inner edge of the tokamak wall is carried out, which otherwise was impossible due to poor accessibility and physical constraints. The position of the antenna is monitored using an electronic scale, which is developed and installed on the bellow. Once the reference position is derived, the linear potentiometer, attached to the bellow, measures the linear distance using position transmitter. The accuracy of measurement obtained in our setup is within +/- 0.5 % and the linearity, along with repeatability is excellent.

Simultaneous Quantification of Gymnemic Acid as Gymnemagenin and Charantin as β-Sitosterol Using Validated HPTLC Densitometric Method.

PubMed

Ahamad, Javed; Amin, Saima; Mir, Showkat R

2015-08-01

Gymnemic acid and charantin are well-established antidiabetic phytosterols found in Gymnema sylvestre and Momordica charantia, respectively. The fact that these plants are often used together in antidiabetic poly-herbal formulations lured us to develop an HPTLC densitometric method for the simultaneous quantification of their bioactive compounds. Indirect estimation of gymnemic acid as gymnemagenin and charantin as β-sitosterol after hydrolysis has been proposed. Aluminum-backed silica gel 60 F254 plates (20 × 10 cm) were used as stationary phase and toluene-ethyl acetate-methanol-formic acid (60 : 20 : 15 : 5, v/v) as mobile phase. Developed chromatogram was scanned at 550 nm after derivatization with modified vanillin-sulfuric acid reagent. Regression analysis of the calibration data showed an excellent linear relationship between peak area versus concentration of the analytes. Linearity was found to be in the range of 500-2,500 and 100-500 ng/band for gymnemagenin and β-sitosterol, respectively. The suitability of the developed HPTLC method for simultaneous estimation of analytes was established by validating it as per the ICH guidelines. The limits of detection and quantification for gymnemagenin were found to be ≈60 and ≈190 ng/band, and those for β-sitosterol ≈30 and ≈90 ng/band, respectively. The developed method was found to be linear (r(2) = 0.9987 and 0.9943), precise (relative standard deviation <1.5 and <2% for intra- and interday precision) and accurate (mean recovery ranged between 98.43-101.44 and 98.68-100.20%) for gymnemagenin and β-sitosterol, respectively. The proposed method was also found specific and robust for quantification of both the analytes and was successfully applied to herbal drugs and in-house herbal formulation without any interference. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

SU-F-T-576: Characterization of Two Dimensional Liquid Filled Detector Array(SRS 1000) in High Precision Cyberknife Robotic Radiosurgery System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muthukumaran, M; Manigandan, D; Murali, V

Purpose: The aim of the study is to characterize a two dimensional liquid filled detector array SRS 1000 for routine QA in Cyberknife Robotic Radiosurgery system. Methods: SRS 1000 consists of 977 liquid filled ionization chambers and is designed to be used in small field SRS/SBRT techniques. The detector array has got two different spacial resolutions. Till field size of 5.5×5.5 cm the spacial resolution is 2.5mm (center to center) and after that till field size of 11 × 11 cm the spacial resolution is 5mm. The size of the detector is 2.3 × 2.3 0.5 mm with a volumemore » of .003 cc. The CyberKnife Robotic Radiosurgery System is a frameless stereotactic radiosurgery system in which a LINAC is mounted on a robotic manipulator to deliver beams with a high sub millimeter accuracy. The SRS 1000’s MU linearity, stability, reproducibility in Cyberknife Robotic Radiosurgery system was measured and investigated. The output factors for fixed and IRIS collimators for all available collimators (5mm till 60 mm) was measured and compared with the measurement done with PTW pin-point ionization chamber. Results: The MU linearity was measured from 2 MU till 1000 MU for doserates in the range of 700cGy/min – 780 cGy/min and compared with the measurement done with pin point chamber The MU linearity was with in 3%. The detector arrays stability and reproducibility was excellent and was withinin 0.5% The measured output factors showed an agreement of better than 2% when compared with the measurements with pinpoint chamber for both fixed and IRIS collimators with all available field sizes. Conclusion: We have characterised PTW 1000 SRS as a precise and accurate measurement tool for routine QA of Cyberknife Robotic radiosurgery system.« less

Evaluation of the dual differential radiometer for remote sensing of sediment and chlorophyll in turbid waters

NASA Technical Reports Server (NTRS)

Witte, W. G.

1975-01-01

The dual differential radiometer (DDR) was tested to determine its capability for measuring suspended sediment and chlorophyll in turbid waters. Measurements were obtained from a boat dock and from a helicopter with combinations of sample and reference filters with peak transmissions at various wavelengths. Water samples were taken concurrently and were analyzed for light scattering, particle count, and total chlorophyll. Least-squares estimates of the linear relationship between DDR output and the water parameters yielded correlation coefficients of less than 0.7. Under the turbid water conditions of the present tests, the DDR did not accurately measure either suspended sediment or chlorophyll. A precise knowledge of the spectral signatures of various pollutants might enable appropriate filters to be selected for tuning the DDR to monitor a particular pollutant.

Quantitative determination of dimethylaminoethanol in cosmetic formulations by nuclear magnetic resonance spectroscopy.

PubMed

Batista, Ivani Aparecida Soares de Andrade; Gonçalves, Maria Inês de Almeida; Singh, Anil Kumar; Hackmann, Erika Rosa Maria Kedor; Santoro, Maria Inês Rocha Miritello

2008-01-01

A nuclear magnetic resonance (NMR) spectroscopic method was validated for the quantitative determination of dimethylaminoethanol (DMAE) in cosmetic formulations. The linearity in the range from 0.5000 to 1.5000 g (DMAE salt/mass maleic acid) presents a correlation coefficient > 0.99 for all DMAE salts. The repeatability (intraday), expressed as relative standard deviation, ranged from 1.08 to 1.44% for samples and 1.31 to 1.88% for raw materials. The detection limit and quantitation limit were 0.0017 and 0.0051 g for DMAE, 0.0018 and 0.0054 g for DMAE bitartrate, and 0.0023 and 0.0071 g for DMAE acetamidobenzoate, respectively. The proposed method is simple, precise, and accurate and can be used in the quality control of raw materials and cosmetic gels containing these compounds as active substances.

Power spectrum precision for redshift space distortions

NASA Astrophysics Data System (ADS)

Linder, Eric V.; Samsing, Johan

2013-02-01

Redshift space distortions in galaxy clustering offer a promising technique for probing the growth rate of structure and testing dark energy properties and gravity. We consider the issue of to what accuracy they need to be modeled in order not to unduly bias cosmological conclusions. Fitting for nonlinear and redshift space corrections to the linear theory real space density power spectrum in bins in wavemode, we analyze both the effect of marginalizing over these corrections and of the bias due to not correcting them fully. While naively subpercent accuracy is required to avoid bias in the unmarginalized case, in the fitting approach the Kwan-Lewis-Linder reconstruction function for redshift space distortions is found to be accurately selfcalibrated with little degradation in dark energy and gravity parameter estimation for a next generation galaxy redshift survey such as BigBOSS.

Chemiluminescence enzyme immunoassay for the determination of sulfamethoxydiazine

NASA Astrophysics Data System (ADS)

Wu, Yongjun; Yu, Songcheng; Yu, Fei; Yan, Nali; Qu, Lingbo; Zhang, Hongquan

2011-10-01

Sulfamethoxydiazine (SMD), which is often used for animal disease treatment, is harmful to human health. No SMD residue should be detected in food in some countries, such as USA and Japan. Therefore, it is significant to develop a high-throughput, high-sensitivity and accurate method for the determination of the content of SMD in food. In this paper, chemiluminescence enzyme immunoassay (CLEIA) was developed for quantification of SMD. For this method, the limit of detection was 3.2 pg/ml, the linear range was from 10 to 2000 pg/ml, the within-day and inter-day precision were below 13% and below 18%, respectively, and the recovery was from 85% to 105%. Milk and egg were selected as samples to be examined with this method, and the result indicated that this CLEIA method was suitable for screening and quality control of food.

Ultra-High Performance Liquid Chromatography (UHPLC) Method for the Determination of Limonene in Sweet Orange (Citrus sinensis) Oil: Implications for Limonene Stability.

PubMed

Bernart, Matthew W

2015-01-01

The citrus-derived bioactive monoterpene limonene is an important industrial commodity and fragrance constituent. An RP isocratic elution C18 ultra-HPLC (UHPLC) method using a superficially porous stationary phase and photodiode array (PDA) detector has been developed for determining the limonene content of sweet orange (Citrus sinensis) oil. The method is fast with a cycle time of 1.2 min, linear, precise, accurate, specific, and stability indicating, and it satisfies U.S. Pharmacopeia suitability parameters. The method may be useful in its present form for limonene processing, or modified for research on more polar compounds of the terpenome. A forced-degradation experiment showed that limonene is degraded by heat in hydro-ethanolic solution. PDA detection facilitates classification of minor components of the essential oil, including β-myrcene.

A novel disturbance-observer based friction compensation scheme for ball and plate system.

PubMed

Wang, Yongkun; Sun, Mingwei; Wang, Zenghui; Liu, Zhongxin; Chen, Zengqiang

2014-03-01

Friction is often ignored when designing a controller for the ball and plate system, which can lead to steady-error and stick-slip phenomena, especially for the small amplitude command. It is difficult to achieve high-precision control performance for the ball and plate system because of its friction. A novel reference compensation strategy is presented to attenuate the aftereffects caused by the friction. To realize this strategy, a linear control law is proposed based on a reduced-order observer. Neither the accurate friction model nor the estimation of specific characteristic parameters is needed in this design. Moreover, the describing function method illustrates that the limit cycle can be avoided. Finally, the comparative mathematical simulations and the practical experiments are used to validate the effectiveness of the proposed method. © 2013 ISA Published by ISA All rights reserved.

Spectrophotometric Determination of Poorly Water Soluble Drug Rosiglitazone Using Hydrotropic Solubilization technique.

PubMed

Sherje, A P; Desai, K J

2011-09-01

In the present investigation, hydrotropic solution of urea was employed as a solubilizing agent for spectrophotometric determination of poorly water-soluble drug rosiglitazone maleate. In solubility determination study, it was found that there was more than 14-folds enhancement in solubility of rosiglitazone maleate in a 6M solution of urea. Rosiglitazone maleate obeys Beer's law in concentration range of 5-300 μg/ml. Linearity of rosiglitazone maleate was found in the range of 80-120% of the label claim. The proposed method has been applied successfully to the analysis of the cited drug in pharmaceutical formulations with good accuracy and precision. The method herein described is new, simple, eco-friendly, economic, and accurate and can be utilized in routine analysis of rosiglitazone maleate in bulk drug and tablet dosage form.

Spectrophotometric Determination of Poorly Water Soluble Drug Rosiglitazone Using Hydrotropic Solubilization technique

PubMed Central

Sherje, A. P.; Desai, K. J.

2011-01-01

In the present investigation, hydrotropic solution of urea was employed as a solubilizing agent for spectrophotometric determination of poorly water-soluble drug rosiglitazone maleate. In solubility determination study, it was found that there was more than 14-folds enhancement in solubility of rosiglitazone maleate in a 6M solution of urea. Rosiglitazone maleate obeys Beer's law in concentration range of 5-300 μg/ml. Linearity of rosiglitazone maleate was found in the range of 80-120% of the label claim. The proposed method has been applied successfully to the analysis of the cited drug in pharmaceutical formulations with good accuracy and precision. The method herein described is new, simple, eco-friendly, economic, and accurate and can be utilized in routine analysis of rosiglitazone maleate in bulk drug and tablet dosage form. PMID:22923874

NaCl nucleation from brine in seeded simulations: Sources of uncertainty in rate estimates.

PubMed

Zimmermann, Nils E R; Vorselaars, Bart; Espinosa, Jorge R; Quigley, David; Smith, William R; Sanz, Eduardo; Vega, Carlos; Peters, Baron

2018-06-14

This work reexamines seeded simulation results for NaCl nucleation from a supersaturated aqueous solution at 298.15 K and 1 bar pressure. We present a linear regression approach for analyzing seeded simulation data that provides both nucleation rates and uncertainty estimates. Our results show that rates obtained from seeded simulations rely critically on a precise driving force for the model system. The driving force vs. solute concentration curve need not exactly reproduce that of the real system, but it should accurately describe the thermodynamic properties of the model system. We also show that rate estimates depend strongly on the nucleus size metric. We show that the rate estimates systematically increase as more stringent local order parameters are used to count members of a cluster and provide tentative suggestions for appropriate clustering criteria.

[Regional scale remote sensing-based yield estimation of winter wheat by using MODIS-NDVI data: a case study of Jining City in Shandong Province].

PubMed

Ren, Jianqiang; Chen, Zhongxin; Tang, Huajun

2006-12-01

Taking Jining City of Shandong Province, one of the most important winter wheat production regions in Huanghuaihai Plain as an example, the winter wheat yield was estimated by using the 250 m MODIS-NDVI data smoothed by Savitzky-Golay filter. The NDVI values between 0. 20 and 0. 80 were selected, and the sum of NDVI value for each county was calculated to build its relation with winter wheat yield. By using stepwise regression method, the linear regression model between NDVI and winter wheat yield was established, with the precision validated by the ground survey data. The results showed that the relative error of predicted yield was between -3.6% and 3.9%, suggesting that the method was relatively accurate and feasible.

Accuracy, precision, usability, and cost of portable silver test methods for ceramic filter factories.

PubMed

Meade, Rhiana D; Murray, Anna L; Mittelman, Anjuliee M; Rayner, Justine; Lantagne, Daniele S

2017-02-01

Locally manufactured ceramic water filters are one effective household drinking water treatment technology. During manufacturing, silver nanoparticles or silver nitrate are applied to prevent microbiological growth within the filter and increase bacterial removal efficacy. Currently, there is no recommendation for manufacturers to test silver concentrations of application solutions or filtered water. We identified six commercially available silver test strips, kits, and meters, and evaluated them by: (1) measuring in quintuplicate six samples from 100 to 1,000 mg/L (application range) and six samples from 0.0 to 1.0 mg/L (effluent range) of silver nanoparticles and silver nitrate to determine accuracy and precision; (2) conducting volunteer testing to assess ease-of-use; and (3) comparing costs. We found no method accurately detected silver nanoparticles, and accuracy ranged from 4 to 91% measurement error for silver nitrate samples. Most methods were precise, but only one method could test both application and effluent concentration ranges of silver nitrate. Volunteers considered test strip methods easiest. The cost for 100 tests ranged from 36 to 1,600 USD. We found no currently available method accurately and precisely measured both silver types at reasonable cost and ease-of-use, thus these methods are not recommended to manufacturers. We recommend development of field-appropriate methods that accurately and precisely measure silver nanoparticle and silver nitrate concentrations.

Performance analysis of mineral mapping method to delineate mineralization zones under tropical region

NASA Astrophysics Data System (ADS)

Wakila, M. H.; Saepuloh, A.; Heriawan, M. N.; Susanto, A.

2016-09-01

Geothermal explorations and productions are currently being intensively conducted at certain areas in Indonesia such as Wayang Windu Geothermal Field (WWGF) in West Java, Indonesia. The WWGF is located at wide area covering about 40 km2. An accurate method to map the distribution of heterogeneity minerals is necessary for wide areas such as WWGF. Mineral mapping is an important method in geothermal explorations to determine the distribution of minerals which indicate the surface manifestations of geothermal system. This study is aimed to determine the most precise and accurate methods for minerals mapping at geothermal field. Field measurements were performed to assess the accuracy of three proposed methods: 1) Minimum Noise Fraction (MNF), utilizing the linear transformation method to eliminate the correlation among the spectra bands and to reduce the noise in the data, 2) Pixel Purity Index (PPI), a designed method to find the most extreme spectrum pixels and their characteristics due to end-members mixing, 3) Spectral Angle Mapper (SAM), an image classification technique by measuring the spectral similarity between an unknown object with spectral reference in n- dimension. The output of those methods were mineral distribution occurrence. The performance of each mapping method was analyzed based on the ground truth data. Among the three proposed method, the SAM classification method is the most appropriate and accurate for mineral mapping related to spatial distribution of alteration minerals.

A segmentation method for lung nodule image sequences based on superpixels and density-based spatial clustering of applications with noise

PubMed Central

Zhang, Wei; Zhang, Xiaolong; Qiang, Yan; Tian, Qi; Tang, Xiaoxian

2017-01-01

The fast and accurate segmentation of lung nodule image sequences is the basis of subsequent processing and diagnostic analyses. However, previous research investigating nodule segmentation algorithms cannot entirely segment cavitary nodules, and the segmentation of juxta-vascular nodules is inaccurate and inefficient. To solve these problems, we propose a new method for the segmentation of lung nodule image sequences based on superpixels and density-based spatial clustering of applications with noise (DBSCAN). First, our method uses three-dimensional computed tomography image features of the average intensity projection combined with multi-scale dot enhancement for preprocessing. Hexagonal clustering and morphological optimized sequential linear iterative clustering (HMSLIC) for sequence image oversegmentation is then proposed to obtain superpixel blocks. The adaptive weight coefficient is then constructed to calculate the distance required between superpixels to achieve precise lung nodules positioning and to obtain the subsequent clustering starting block. Moreover, by fitting the distance and detecting the change in slope, an accurate clustering threshold is obtained. Thereafter, a fast DBSCAN superpixel sequence clustering algorithm, which is optimized by the strategy of only clustering the lung nodules and adaptive threshold, is then used to obtain lung nodule mask sequences. Finally, the lung nodule image sequences are obtained. The experimental results show that our method rapidly, completely and accurately segments various types of lung nodule image sequences. PMID:28880916

A feasible, economical, and accurate analytical method for simultaneous determination of six alkaloid markers in Aconiti Lateralis Radix Praeparata from different manufacturing sources and processing ways.

PubMed

Zhang, Yi-Bei; DA, Juan; Zhang, Jing-Xian; Li, Shang-Rong; Chen, Xin; Long, Hua-Li; Wang, Qiu-Rong; Cai, Lu-Ying; Yao, Shuai; Hou, Jin-Jun; Wu, Wan-Ying; Guo, De-An

2017-04-01

Aconiti Lateralis Radix Praeparata (Fuzi) is a commonly used traditional Chinese medicine in clinic for its potency in restoring yang and rescuing from collapse. Aconiti alkaloids, mainly including monoester-diterpenoidaconitines (MDAs) and diester-diterpenoidaconitines (DDAs), are considered to act as both bioactive and toxic constituents. In the present study, a feasible, economical, and accurate HPLC method for simultaneous determination of six alkaloid markers using the Single Standard for Determination of Multi-Components (SSDMC) method was developed and fully validated. Benzoylmesaconine was used as the unique reference standard. This method was proven as accurate (recovery varying between 97.5%-101.8%, RSD < 3%), precise (RSD 0.63%-2.05%), and linear (R > 0.999 9) over the concentration ranges, and subsequently applied to quantitative evaluation of 62 batches of samples, among which 45 batches were from good manufacturing practice (GMP) facilities and 17 batches from the drug market. The contents were then analyzed by principal component analysis (PCA) and homogeneity test. The present study provided valuable information for improving the quality standard of Aconiti Lateralis Radix Praeparata. The developed method also has the potential in analysis of other Aconitum species, such as Aconitum carmichaelii (prepared parent root) and Aconitum kusnezoffii (prepared root). Copyright © 2017 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Precision linear ramp function generator

DOEpatents

Jatko, W.B.; McNeilly, D.R.; Thacker, L.H.

1984-08-01

A ramp function generator is provided which produces a precise linear ramp function which is repeatable and highly stable. A derivative feedback loop is used to stabilize the output of an integrator in the forward loop and control the ramp rate. The ramp may be started from a selected baseline voltage level and the desired ramp rate is selected by applying an appropriate constant voltage to the input of the integrator.

Precision linear ramp function generator

DOEpatents

Jatko, W. Bruce; McNeilly, David R.; Thacker, Louis H.

1986-01-01

A ramp function generator is provided which produces a precise linear ramp unction which is repeatable and highly stable. A derivative feedback loop is used to stabilize the output of an integrator in the forward loop and control the ramp rate. The ramp may be started from a selected baseline voltage level and the desired ramp rate is selected by applying an appropriate constant voltage to the input of the integrator.

Moving to the Beat and Singing are Linked in Humans

PubMed Central

Dalla Bella, Simone; Berkowska, Magdalena; Sowiński, Jakub

2015-01-01

The abilities to sing and to move to the beat of a rhythmic auditory stimulus emerge early during development, and both engage perceptual, motor, and sensorimotor processes. These similarities between singing and synchronization to a beat may be rooted in biology. Patel (2008) has suggested that motor synchronization to auditory rhythms may have emerged during evolution as a byproduct of selection for vocal learning (“vocal learning and synchronization hypothesis”). This view predicts a strong link between vocal performance and synchronization skills in humans. Here, we tested this prediction by asking occasional singers to tap along with auditory pulse trains and to imitate familiar melodies. Both vocal imitation and synchronization skills were measured in terms of accuracy and precision or consistency. Accurate and precise singers tapped more in the vicinity of the pacing stimuli (i.e., they were more accurate) than less accurate and less precise singers. Moreover, accurate singers were more consistent when tapping to the beat. These differences cannot be ascribed to basic motor skills or to motivational factors. Individual differences in terms of singing proficiency and synchronization skills may reflect the variability of a shared sensorimotor translation mechanism. PMID:26733370

A simple, stable, and accurate linear tetrahedral finite element for transient, nearly, and fully incompressible solid dynamics: A dynamic variational multiscale approach [A simple, stable, and accurate tetrahedral finite element for transient, nearly incompressible, linear and nonlinear elasticity: A dynamic variational multiscale approach

DOE PAGES

Scovazzi, Guglielmo; Carnes, Brian; Zeng, Xianyi; ...

2015-11-12

Here, we propose a new approach for the stabilization of linear tetrahedral finite elements in the case of nearly incompressible transient solid dynamics computations. Our method is based on a mixed formulation, in which the momentum equation is complemented by a rate equation for the evolution of the pressure field, approximated with piece-wise linear, continuous finite element functions. The pressure equation is stabilized to prevent spurious pressure oscillations in computations. Incidentally, it is also shown that many stabilized methods previously developed for the static case do not generalize easily to transient dynamics. Extensive tests in the context of linear andmore » nonlinear elasticity are used to corroborate the claim that the proposed method is robust, stable, and accurate.« less

A simple, stable, and accurate linear tetrahedral finite element for transient, nearly, and fully incompressible solid dynamics: A dynamic variational multiscale approach [A simple, stable, and accurate tetrahedral finite element for transient, nearly incompressible, linear and nonlinear elasticity: A dynamic variational multiscale approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scovazzi, Guglielmo; Carnes, Brian; Zeng, Xianyi

Here, we propose a new approach for the stabilization of linear tetrahedral finite elements in the case of nearly incompressible transient solid dynamics computations. Our method is based on a mixed formulation, in which the momentum equation is complemented by a rate equation for the evolution of the pressure field, approximated with piece-wise linear, continuous finite element functions. The pressure equation is stabilized to prevent spurious pressure oscillations in computations. Incidentally, it is also shown that many stabilized methods previously developed for the static case do not generalize easily to transient dynamics. Extensive tests in the context of linear andmore » nonlinear elasticity are used to corroborate the claim that the proposed method is robust, stable, and accurate.« less

Variable-pulse switching circuit accurately controls solenoid-valve actuations

NASA Technical Reports Server (NTRS)

Gillett, J. D.

1967-01-01

Solid state circuit generating adjustable square wave pulses of sufficient power operates a 28 volt dc solenoid valve at precise time intervals. This circuit is used for precise time control of fluid flow in combustion experiments.

The compression–error trade-off for large gridded data sets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silver, Jeremy D.; Zender, Charles S.

The netCDF-4 format is widely used for large gridded scientific data sets and includes several compression methods: lossy linear scaling and the non-lossy deflate and shuffle algorithms. Many multidimensional geoscientific data sets exhibit considerable variation over one or several spatial dimensions (e.g., vertically) with less variation in the remaining dimensions (e.g., horizontally). On such data sets, linear scaling with a single pair of scale and offset parameters often entails considerable loss of precision. We introduce an alternative compression method called "layer-packing" that simultaneously exploits lossy linear scaling and lossless compression. Layer-packing stores arrays (instead of a scalar pair) of scalemore » and offset parameters. An implementation of this method is compared with lossless compression, storing data at fixed relative precision (bit-grooming) and scalar linear packing in terms of compression ratio, accuracy and speed. When viewed as a trade-off between compression and error, layer-packing yields similar results to bit-grooming (storing between 3 and 4 significant figures). Bit-grooming and layer-packing offer significantly better control of precision than scalar linear packing. Relative performance, in terms of compression and errors, of bit-groomed and layer-packed data were strongly predicted by the entropy of the exponent array, and lossless compression was well predicted by entropy of the original data array. Layer-packed data files must be "unpacked" to be readily usable. The compression and precision characteristics make layer-packing a competitive archive format for many scientific data sets.« less

The compression–error trade-off for large gridded data sets

DOE PAGES

Silver, Jeremy D.; Zender, Charles S.

2017-01-27

The netCDF-4 format is widely used for large gridded scientific data sets and includes several compression methods: lossy linear scaling and the non-lossy deflate and shuffle algorithms. Many multidimensional geoscientific data sets exhibit considerable variation over one or several spatial dimensions (e.g., vertically) with less variation in the remaining dimensions (e.g., horizontally). On such data sets, linear scaling with a single pair of scale and offset parameters often entails considerable loss of precision. We introduce an alternative compression method called "layer-packing" that simultaneously exploits lossy linear scaling and lossless compression. Layer-packing stores arrays (instead of a scalar pair) of scalemore » and offset parameters. An implementation of this method is compared with lossless compression, storing data at fixed relative precision (bit-grooming) and scalar linear packing in terms of compression ratio, accuracy and speed. When viewed as a trade-off between compression and error, layer-packing yields similar results to bit-grooming (storing between 3 and 4 significant figures). Bit-grooming and layer-packing offer significantly better control of precision than scalar linear packing. Relative performance, in terms of compression and errors, of bit-groomed and layer-packed data were strongly predicted by the entropy of the exponent array, and lossless compression was well predicted by entropy of the original data array. Layer-packed data files must be "unpacked" to be readily usable. The compression and precision characteristics make layer-packing a competitive archive format for many scientific data sets.« less

Assessment of the performance of automated focimeters in the measurement of single vision spectacle lenses.

PubMed

Chu, Byoung-Sun; Ngo, Thao P T; Cheng, Brian B; Dain, Stephen J

2014-07-01

The accuracy and precision of any instrument should not be taken for granted. While there is an international standard for checking focimeters, there is no report of any study on their performance. A sample set of 51 focimeters (11 brands), were used to measure the spherical power of a set of lenses and the prismatic power of two lenses complying with ISO 9342-1:2005 and other calibrated prismatic lenses and the spherical power of some grey filters. The mean measured spherical power corresponded very closely with the calibrated values; however, the spread of results was substantial and 10 focimeters did not comply with ISO 8598:1996. The measurement of prism was much more accurate and precise and all the focimeters complied easily. With the grey filters, about one-third of the focimeters either showed erratic reading or an error with the equivalent of category 4 sunglasses. On the other hand, nine focimeters had stable and accurate reading on a filter with a luminous transmittance of 0.5 per cent. These results confirm that, in common with all other measurement instruments, there is a need to ensure that a focimeter is reading accurately and precisely over the range of refractive powers and luminous transmittances. The accurate and precise performance of an automated focimeter over its working life cannot be assumed. Checking before purchase with a set of calibrated lenses and some dark sunglass tints will indicate the suitability of a focimeter. Routine checking with the calibrated lenses will inform the users if a focimeter continues to indicate accurately. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

Accurate artificial boundary conditions for the semi-discretized linear Schrödinger and heat equations on rectangular domains

NASA Astrophysics Data System (ADS)

Ji, Songsong; Yang, Yibo; Pang, Gang; Antoine, Xavier

2018-01-01

The aim of this paper is to design some accurate artificial boundary conditions for the semi-discretized linear Schrödinger and heat equations in rectangular domains. The Laplace transform in time and discrete Fourier transform in space are applied to get Green's functions of the semi-discretized equations in unbounded domains with single-source. An algorithm is given to compute these Green's functions accurately through some recurrence relations. Furthermore, the finite-difference method is used to discretize the reduced problem with accurate boundary conditions. Numerical simulations are presented to illustrate the accuracy of our method in the case of the linear Schrödinger and heat equations. It is shown that the reflection at the corners is correctly eliminated.

Microhartree precision in density functional theory calculations

NASA Astrophysics Data System (ADS)

Gulans, Andris; Kozhevnikov, Anton; Draxl, Claudia

2018-04-01

To address ultimate precision in density functional theory calculations we employ the full-potential linearized augmented plane-wave + local-orbital (LAPW + lo) method and justify its usage as a benchmark method. LAPW + lo and two completely unrelated numerical approaches, the multiresolution analysis (MRA) and the linear combination of atomic orbitals, yield total energies of atoms with mean deviations of 0.9 and 0.2 μ Ha , respectively. Spectacular agreement with the MRA is reached also for total and atomization energies of the G2-1 set consisting of 55 molecules. With the example of α iron we demonstrate the capability of LAPW + lo to reach μ Ha /atom precision also for periodic systems, which allows also for the distinction between the numerical precision and the accuracy of a given functional.

Simultaneous determination of pyrroquinazoline alkaloids and flavonoids in Adhatoda beddomei and Adhatoda vasica and their marketed herbal formulations using ultra-high-performance liquid chromatography coupled with triple quadrupole linear ion trap mass spectrometry.

PubMed

Singh, Awantika; Kumar, Sunil; Bajpai, Vikas; Kumar, Brijesh

2017-03-01

Adhatoda beddomei and Adhatoda vasica leaf, known as 'Vasaka' and/or 'Vasa' in Ayurveda and 'Malabar nut' in English, is an official drug in the Indian Pharmacopoeia. The medicinal properties of these plants are due to the presence of pyrroquinazoline alkaloids. An UHPLC-ESI/MS/MS method in both positive and negative electrospray ionization in multiple-reaction-monitoring mode was developed and validated for the estimation of alkaloids and flavonoids in Adhatoda species and their marketed herbal formulations. Chromatographic separation was achieved on an Acquity UPLC® BEH C 18 -column using a gradient elution with 0.1% formic acid in water and methanol. The developed method was validated as per International Conference on Harmonization guidelines and found to be accurate with overall recovery in the range 94.2-105.0% (RSD ≤ 1.71%), precise (RSD ≤ 3.44%) and linear (R 2  ≥ 0.9992) over the concentration range of 0.5-1000 ng/mL. The total content of alkaloids and flavonoids were highest in the chloroform and aqueous fraction of A. vasica leaf, respectively. The results indicated that the developed method was simple, rapid, sensitive, selective and accurate for the estimation of multiple bioactive constituents in crude mixture, and therefore could make a contribution to the quality control of Adhatoda species and its derived herbal formulations. Copyright © 2016 John Wiley & Sons, Ltd.

A 100-Year Review: Methods and impact of genetic selection in dairy cattle-From daughter-dam comparisons to deep learning algorithms.

PubMed

Weigel, K A; VanRaden, P M; Norman, H D; Grosu, H

2017-12-01

In the early 1900s, breed society herdbooks had been established and milk-recording programs were in their infancy. Farmers wanted to improve the productivity of their cattle, but the foundations of population genetics, quantitative genetics, and animal breeding had not been laid. Early animal breeders struggled to identify genetically superior families using performance records that were influenced by local environmental conditions and herd-specific management practices. Daughter-dam comparisons were used for more than 30 yr and, although genetic progress was minimal, the attention given to performance recording, genetic theory, and statistical methods paid off in future years. Contemporary (herdmate) comparison methods allowed more accurate accounting for environmental factors and genetic progress began to accelerate when these methods were coupled with artificial insemination and progeny testing. Advances in computing facilitated the implementation of mixed linear models that used pedigree and performance data optimally and enabled accurate selection decisions. Sequencing of the bovine genome led to a revolution in dairy cattle breeding, and the pace of scientific discovery and genetic progress accelerated rapidly. Pedigree-based models have given way to whole-genome prediction, and Bayesian regression models and machine learning algorithms have joined mixed linear models in the toolbox of modern animal breeders. Future developments will likely include elucidation of the mechanisms of genetic inheritance and epigenetic modification in key biological pathways, and genomic data will be used with data from on-farm sensors to facilitate precision management on modern dairy farms. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Maternal Weight Gain as a Predictor of Litter Size in Swiss Webster, C57BL/6J, and BALB/cJ mice.

PubMed

Finlay, James B; Liu, Xueli; Ermel, Richard W; Adamson, Trinka W

2015-11-01

An important task facing both researchers and animal core facilities is producing sufficient mice for a given project. The inherent biologic variability of mouse reproduction and litter size further challenges effective research planning. A lack of precision in project planning contributes to the high cost of animal research, overproduction (thus waste) of animals, and inappropriate allocation of facility resources. To examine the extent daily prepartum maternal weight gain predicts litter size in 2 commonly used mouse strains (BALB/cJ and C57BL/6J) and one mouse stock (Swiss Webster), we weighed ≥ 25 pregnant dams of each strain or stock daily from the morning on which a vaginal plug (day 0) was present. On the morning when dams delivered their pups, we recorded the weight of the dam, the weight of the litter itself, and the number of pups. Litter sizes ranged from 1 to 7 pups for BALB/cJ, 2 to 13 for Swiss Webster, and 5 to 11 for C57BL/6J mice. Linear regression models (based on weight change from day 0) demonstrated that maternal weight gain at day 9 (BALB/cJ), day 11 (Swiss Webster), or day 14 (C57BL/6J) was a significant predictor of litter size. When tested prospectively, the linear regression model for each strain or stock was found to be accurate. These data indicate that the number of pups that will be born can be estimated accurately by using maternal weight gain at specific or stock-specific time points.

Expanded modeling of temperature-dependent dielectric properties for microwave thermal ablation

PubMed Central

Ji, Zhen; Brace, Christopher L

2011-01-01

Microwaves are a promising source for thermal tumor ablation due to their ability to rapidly heat dispersive biological tissues, often to temperatures in excess of 100 °C. At these high temperatures, tissue dielectric properties change rapidly and, thus, so do the characteristics of energy delivery. Precise knowledge of how tissue dielectric properties change during microwave heating promises to facilitate more accurate simulation of device performance and helps optimize device geometry and energy delivery parameters. In this study, we measured the dielectric properties of liver tissue during high-temperature microwave heating. The resulting data were compiled into either a sigmoidal function of temperature or an integration of the time–temperature curve for both relative permittivity and effective conductivity. Coupled electromagnetic–thermal simulations of heating produced by a single monopole antenna using the new models were then compared to simulations with existing linear and static models, and experimental temperatures in liver tissue. The new sigmoidal temperature-dependent model more accurately predicted experimental temperatures when compared to temperature–time integrated or existing models. The mean percent differences between simulated and experimental temperatures over all times were 4.2% for sigmoidal, 10.1% for temperature–time integration, 27.0% for linear and 32.8% for static models at the antenna input power of 50 W. Correcting for tissue contraction improved agreement for powers up to 75 W. The sigmoidal model also predicted substantial changes in heating pattern due to dehydration. We can conclude from these studies that a sigmoidal model of tissue dielectric properties improves prediction of experimental results. More work is needed to refine and generalize this model. PMID:21791728

Imaging tristimulus colorimeter for the evaluation of color in printed textiles

NASA Astrophysics Data System (ADS)

Hunt, Martin A.; Goddard, James S., Jr.; Hylton, Kathy W.; Karnowski, Thomas P.; Richards, Roger K.; Simpson, Marc L.; Tobin, Kenneth W., Jr.; Treece, Dale A.

1999-03-01

The high-speed production of textiles with complicated printed patterns presents a difficult problem for a colorimetric measurement system. Accurate assessment of product quality requires a repeatable measurement using a standard color space, such as CIELAB, and the use of a perceptually based color difference formula, e.g. (Delta) ECMC color difference formula. Image based color sensors used for on-line measurement are not colorimetric by nature and require a non-linear transformation of the component colors based on the spectral properties of the incident illumination, imaging sensor, and the actual textile color. This research and development effort describes a benchtop, proof-of-principle system that implements a projection onto convex sets (POCS) algorithm for mapping component color measurements to standard tristimulus values and incorporates structural and color based segmentation for improved precision and accuracy. The POCS algorithm consists of determining the closed convex sets that describe the constraints on the reconstruction of the true tristimulus values based on the measured imperfect values. We show that using a simulated D65 standard illuminant, commercial filters and a CCD camera, accurate (under perceptibility limits) per-region based (Delta) ECMC values can be measured on real textile samples.

Determination of rivaroxaban in patient's plasma samples by anti-Xa chromogenic test associated to High Performance Liquid Chromatography tandem Mass Spectrometry (HPLC-MS/MS).

PubMed

Derogis, Priscilla Bento Matos; Sanches, Livia Rentas; de Aranda, Valdir Fernandes; Colombini, Marjorie Paris; Mangueira, Cristóvão Luis Pitangueira; Katz, Marcelo; Faulhaber, Adriana Caschera Leme; Mendes, Claudio Ernesto Albers; Ferreira, Carlos Eduardo Dos Santos; França, Carolina Nunes; Guerra, João Carlos de Campos

2017-01-01

Rivaroxaban is an oral direct factor Xa inhibitor, therapeutically indicated in the treatment of thromboembolic diseases. As other new oral anticoagulants, routine monitoring of rivaroxaban is not necessary, but important in some clinical circumstances. In our study a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was validated to measure rivaroxaban plasmatic concentration. Our method used a simple sample preparation, protein precipitation, and a fast chromatographic run. It was developed a precise and accurate method, with a linear range from 2 to 500 ng/mL, and a lower limit of quantification of 4 pg on column. The new method was compared to a reference method (anti-factor Xa activity) and both presented a good correlation (r = 0.98, p < 0.001). In addition, we validated hemolytic, icteric or lipemic plasma samples for rivaroxaban measurement by HPLC-MS/MS without interferences. The chromogenic and HPLC-MS/MS methods were highly correlated and should be used as clinical tools for drug monitoring. The method was applied successfully in a group of 49 real-life patients, which allowed an accurate determination of rivaroxaban in peak and trough levels.

A new LC-MS based method to quantitate exogenous recombinant transferrin in cerebrospinal fluid: a potential approach for pharmacokinetic studies of transferrin-based therapeutics in the central nervous system

PubMed Central

Wang, Shunhai; Bobst, Cedric E.; Kaltashov, Igor A.

2018-01-01

Transferrin (Tf) is an 80 kDa iron-binding protein which is viewed as a promising drug carrier to target the central nervous system due to its ability to penetrate the blood-brain barrier (BBB). Among the many challenges during the development of Tf-based therapeutics, sensitive and accurate quantitation of the administered Tf in cerebrospinal fluid (CSF) remains particularly difficult due to the presence of abundant endogenous Tf. Herein, we describe the development of a new LC-MS based method for sensitive and accurate quantitation of exogenous recombinant human Tf in rat CSF. By taking advantage of a His-tag present in recombinant Tf and applying Ni affinity purification, the exogenous hTf can be greatly enriched from rat CSF, despite the presence of the abundant endogenous protein. Additionally, we applied a newly developed O18-labeling technique that can generate internal standards at the protein level, which greatly improved the accuracy and robustness of quantitation. The developed method was investigated for linearity, accuracy, precision and lower limit of quantitation, all of which met the commonly accepted criteria for bioanalytical method validation. PMID:26307718

Open-source Software for Demand Forecasting of Clinical Laboratory Test Volumes Using Time-series Analysis.

PubMed

Mohammed, Emad A; Naugler, Christopher

2017-01-01

Demand forecasting is the area of predictive analytics devoted to predicting future volumes of services or consumables. Fair understanding and estimation of how demand will vary facilitates the optimal utilization of resources. In a medical laboratory, accurate forecasting of future demand, that is, test volumes, can increase efficiency and facilitate long-term laboratory planning. Importantly, in an era of utilization management initiatives, accurately predicted volumes compared to the realized test volumes can form a precise way to evaluate utilization management initiatives. Laboratory test volumes are often highly amenable to forecasting by time-series models; however, the statistical software needed to do this is generally either expensive or highly technical. In this paper, we describe an open-source web-based software tool for time-series forecasting and explain how to use it as a demand forecasting tool in clinical laboratories to estimate test volumes. This tool has three different models, that is, Holt-Winters multiplicative, Holt-Winters additive, and simple linear regression. Moreover, these models are ranked and the best one is highlighted. This tool will allow anyone with historic test volume data to model future demand.

Open-source Software for Demand Forecasting of Clinical Laboratory Test Volumes Using Time-series Analysis

PubMed Central

Mohammed, Emad A.; Naugler, Christopher

2017-01-01

Background: Demand forecasting is the area of predictive analytics devoted to predicting future volumes of services or consumables. Fair understanding and estimation of how demand will vary facilitates the optimal utilization of resources. In a medical laboratory, accurate forecasting of future demand, that is, test volumes, can increase efficiency and facilitate long-term laboratory planning. Importantly, in an era of utilization management initiatives, accurately predicted volumes compared to the realized test volumes can form a precise way to evaluate utilization management initiatives. Laboratory test volumes are often highly amenable to forecasting by time-series models; however, the statistical software needed to do this is generally either expensive or highly technical. Method: In this paper, we describe an open-source web-based software tool for time-series forecasting and explain how to use it as a demand forecasting tool in clinical laboratories to estimate test volumes. Results: This tool has three different models, that is, Holt-Winters multiplicative, Holt-Winters additive, and simple linear regression. Moreover, these models are ranked and the best one is highlighted. Conclusion: This tool will allow anyone with historic test volume data to model future demand. PMID:28400996

Indirect spectrophotometric determination of arbutin, whitening agent through oxidation by periodate and complexation with ferric chloride

NASA Astrophysics Data System (ADS)

Barsoom, B. N.; Abdelsamad, A. M. E.; Adib, N. M.

2006-07-01

A simple and accurate spectrophotometric method for the determination of arbutin (glycosylated hydroquinone) is described. It is based on the oxidation of arbutin by periodate in presence of iodate. Excess periodate causes liberation of iodine at pH 8.0. The unreacted periodate is determined by measurement of the liberated iodine spectrophotometrically in the wavelength range (300-500 nm). A calibration curve was constructed for more accurate results and the correlation coefficient of linear regression analysis was -0.9778. The precision of this method was better than 6.17% R.S.D. ( n = 3). Regression analysis of Bear-Lambert plot shows good correlation in the concentration range 25-125 ug/ml. The identification limit was determined to be 25 ug/ml a detailed study of the reaction conditions was carried out, including effect of changing pH, time, temperature and volume of periodate. Analyzing pure and authentic samples containing arbutin tested the validity of the proposed method which has an average percent recovery of 100.86%. An alternative method is also proposed which involves a complexation reaction between arbutin and ferric chloride solution. The produced complex which is yellowish-green in color was determined spectophotometrically.

Precise measurement of coupling strength and high temperature quantum effect in a nonlinearly coupled qubit-oscillator system

NASA Astrophysics Data System (ADS)

Ge, Li; Zhao, Nan

2018-04-01

We study the coherence dynamics of a qubit coupled to a harmonic oscillator with both linear and quadratic interactions. As long as the linear coupling strength is much smaller than the oscillator frequency, the long time behavior of the coherence is dominated by the quadratic coupling strength g 2. The coherence decays and revives at a period , with the width of coherence peak decreasing as the temperature increases, hence providing a way to measure g 2 precisely without cooling. Unlike the case of linear coupling, here the coherence dynamics never reduces to the classical limit in which the oscillator is classical. Finally, the validity of linear coupling approximation is discussed and the coherence under Hahn-echo is evaluated.

A stopping criterion for the iterative solution of partial differential equations

NASA Astrophysics Data System (ADS)

Rao, Kaustubh; Malan, Paul; Perot, J. Blair

2018-01-01

A stopping criterion for iterative solution methods is presented that accurately estimates the solution error using low computational overhead. The proposed criterion uses information from prior solution changes to estimate the error. When the solution changes are noisy or stagnating it reverts to a less accurate but more robust, low-cost singular value estimate to approximate the error given the residual. This estimator can also be applied to iterative linear matrix solvers such as Krylov subspace or multigrid methods. Examples of the stopping criterion's ability to accurately estimate the non-linear and linear solution error are provided for a number of different test cases in incompressible fluid dynamics.

Simultaneous determination of dextromethorphan, dextrorphan, and guaifenesin in human plasma using semi-automated liquid/liquid extraction and gradient liquid chromatography tandem mass spectrometry.

PubMed

Eichhold, Thomas H; McCauley-Myers, David L; Khambe, Deepa A; Thompson, Gary A; Hoke, Steven H

2007-01-17

A method for the simultaneous determination of dextromethorphan (DEX), dextrorphan (DET), and guaifenesin (GG) in human plasma was developed, validated, and applied to determine plasma concentrations of these compounds in samples from six clinical pharmacokinetic (PK) studies. Semi-automated liquid handling systems were used to perform the majority of the sample manipulation including liquid/liquid extraction (LLE) of the analytes from human plasma. Stable-isotope-labeled analogues were utilized as internal standards (ISTDs) for each analyte to facilitate accurate and precise quantification. Extracts were analyzed using gradient liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Use of semi-automated LLE with LC-MS/MS proved to be a very rugged and reliable approach for analysis of more than 6200 clinical study samples. The lower limit of quantification was validated at 0.010, 0.010, and 1.0 ng/mL of plasma for DEX, DET, and GG, respectively. Accuracy and precision of quality control (QC) samples for all three analytes met FDA Guidance criteria of +/-15% for average QC accuracy with coefficients of variation less than 15%. Data from the thorough evaluation of the method during development, validation, and application are presented to characterize selectivity, linearity, over-range sample analysis, accuracy, precision, autosampler carry-over, ruggedness, extraction efficiency, ionization suppression, and stability. Pharmacokinetic data are also provided to illustrate improvements in systemic drug and metabolite concentration-time profiles that were achieved by formulation optimization.

Automatic stent strut detection in intravascular OCT images using image processing and classification technique

NASA Astrophysics Data System (ADS)

Lu, Hong; Gargesha, Madhusudhana; Wang, Zhao; Chamie, Daniel; Attizani, Guilherme F.; Kanaya, Tomoaki; Ray, Soumya; Costa, Marco A.; Rollins, Andrew M.; Bezerra, Hiram G.; Wilson, David L.

2013-02-01

Intravascular OCT (iOCT) is an imaging modality with ideal resolution and contrast to provide accurate in vivo assessments of tissue healing following stent implantation. Our Cardiovascular Imaging Core Laboratory has served >20 international stent clinical trials with >2000 stents analyzed. Each stent requires 6-16hrs of manual analysis time and we are developing highly automated software to reduce this extreme effort. Using classification technique, physically meaningful image features, forward feature selection to limit overtraining, and leave-one-stent-out cross validation, we detected stent struts. To determine tissue coverage areas, we estimated stent "contours" by fitting detected struts and interpolation points from linearly interpolated tissue depths to a periodic cubic spline. Tissue coverage area was obtained by subtracting lumen area from the stent area. Detection was compared against manual analysis of 40 pullbacks. We obtained recall = 90+/-3% and precision = 89+/-6%. When taking struts deemed not bright enough for manual analysis into consideration, precision improved to 94+/-6%. This approached inter-observer variability (recall = 93%, precision = 96%). Differences in stent and tissue coverage areas are 0.12 +/- 0.41 mm2 and 0.09 +/- 0.42 mm2, respectively. We are developing software which will enable visualization, review, and editing of automated results, so as to provide a comprehensive stent analysis package. This should enable better and cheaper stent clinical trials, so that manufacturers can optimize the myriad of parameters (drug, coverage, bioresorbable versus metal, etc.) for stent design.

A comparative study of smart spectrophotometric methods for simultaneous determination of sitagliptin phosphate and metformin hydrochloride in their binary mixture.

PubMed

Lotfy, Hayam M; Mohamed, Dalia; Mowaka, Shereen

2015-01-01

Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at λmax 232 nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision. Copyright © 2015 Elsevier B.V. All rights reserved.

Development and validation of an analytical method for regorafenib and its metabolites in mouse plasma.

PubMed

Fu, Qiang; Chen, Mingqing; Hu, Shuiying; McElroy, Craig A; Mathijssen, Ron H; Sparreboom, Alex; Baker, Sharyn D

2018-05-05

An analytical method was developed for measuring the effect of OATP1B2 deficiency on plasma levels of the kinase inhibitor regorafenib and its metabolites regorafenib-N-oxide, N-desmethyl-regorafenib-N-oxide, and regorafenib-N-β-glucuronide (RG) in mice. Compounds were separated by liquid chromatography and monitored by a triple quadrupole mass spectrometer in the selected reaction monitoring mode after positive electrospray ionization. All calibration curves were linear in the selected concentration range (R 2  ≥ 0.99). The lower limit of quantification was 5 ng/mL for the four analytes. Within-day precisions, between-day precisions, and accuracies were 2.59-6.82%, 3.97-11.3%, and 94.5-111%, respectively. The identification and structure elucidation of RG, isolated from human urine, was performed by NMR. Compared with wild-type mice given regorafenib (10 mg/kg), deficiency of the drug transporter OATP1B2 in vivo had minimal effects on plasma levels of parent drug and the metabolite regorafenib-N-oxide, and N-desmethyl-regorafenib-N-oxide. However, the area under the curve and peak levels of RG were increased by 5.6-fold and 5.1-fold, respectively, in OATP1B2-knockout mice. In conclusion, our analytical method allowed accurate and precise quantitation of regorafenib and its main metabolites in mouse plasma, and is suitable for evaluation of transporter-dependent pharmacokinetic properties of these agents in vivo. Published by Elsevier B.V.

Evaluation of laser diode thermal desorption-tandem mass spectrometry (LDTD-MS-MS) in forensic toxicology.

PubMed

Bynum, Nichole D; Moore, Katherine N; Grabenauer, Megan

2014-10-01

Many forensic laboratories experience backlogs due to increased drug-related cases. Laser diode thermal desorption (LDTD) has demonstrated its applicability in other scientific areas by providing data comparable with instrumentation, such as liquid chromatography-tandem mass spectrometry, in less time. LDTD-MS-MS was used to validate 48 compounds in drug-free human urine and blood for screening or quantitative analysis. Carryover, interference, limit of detection, limit of quantitation, matrix effect, linearity, precision and accuracy and stability were evaluated. Quantitative analysis indicated that LDTD-MS-MS produced precise and accurate results with the average overall within-run precision in urine and blood represented by a %CV <14.0 and <7.0, respectively. The accuracy for all drugs in urine ranged from 88.9 to 104.5% and 91.9 to 107.1% in blood. Overall, LDTD has the potential for use in forensic toxicology but before it can be successfully implemented that there are some challenges that must be addressed. Although the advantages of the LDTD system include minimal maintenance and rapid analysis (∼10 s per sample) which makes it ideal for high-throughput forensic laboratories, a major disadvantage is its inability or difficulty analyzing isomers and isobars due to the lack of chromatography without the use of high-resolution MS; therefore, it would be best implemented as a screening technique. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Simple and Specific Stability- Indicating RP-HPLC Method for Routine Assay of Adefovir Dipivoxil in Bulk and Tablet Dosage Form.

PubMed

Darsazan, Bahar; Shafaati, Alireza; Mortazavi, Seyed Alireza; Zarghi, Afshin

2017-01-01

A simple and reliable stability-indicating RP-HPLC method was developed and validated for analysis of adefovir dipivoxil (ADV).The chromatographic separation was performed on a C 18 column using a mixture of acetonitrile-citrate buffer (10 mM at pH 5.2) 36:64 (%v/v) as mobile phase, at a flow rate of 1.5 mL/min. Detection was carried out at 260 nm and a sharp peak was obtained for ADV at a retention time of 5.8 ± 0.01 min. No interferences were observed from its stress degradation products. The method was validated according to the international guidelines. Linear regression analysis of data for the calibration plot showed a linear relationship between peak area and concentration over the range of 0.5-16 μg/mL; the regression coefficient was 0.9999and the linear regression equation was y = 24844x-2941.3. The detection (LOD) and quantification (LOQ) limits were 0.12 and 0.35 μg/mL, respectively. The results proved the method was fast (analysis time less than 7 min), precise, reproducible, and accurate for analysis of ADV over a wide range of concentration. The proposed specific method was used for routine quantification of ADV in pharmaceutical bulk and a tablet dosage form.

"Center punch" and "whole spot" bioanalysis of apixaban in human dried blood spot samples by UHPLC-MS/MS.

PubMed

Zheng, Naiyu; Yuan, Long; Ji, Qin C; Mangus, Heidi; Song, Yan; Frost, Charles; Zeng, Jianing; Aubry, Anne-Françoise; Arnold, Mark E

2015-04-15

Apixaban (Eliquis™) was developed by Bristol-Myers Squibb (BMS) and Pfizer to use as an antithrombotic/anticoagulant agent and has been recently approved for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. A clinical study of apixaban, sponsored by BMS and Pfizer, included a pilot exploratory portion to evaluate the potential for future drug concentration monitoring using dried blood spot (DBS) sample collection. For DBS sample collection, a fixed blood volume was dispensed onto a DBS card by either regular volumetric pipette (venous blood collection) or capillary dispenser (finger prick blood collection). A 96-well semi-automated liquid-liquid extraction sample preparation procedure was developed to provide clean extracts for UHPLC-MS/MS quantitation. Assays using both partial-spot center punch and whole spot punch were developed and validated. The linear dynamic ranges for all the analyses were from 0.5 to 500 ng/mL. The coefficient of determination (r(2)) values was >0.9944 for all the validation runs. For the center punch approach, the intra-assay precision (%CV) was within 4.4% and inter-assay precision was within 2.6%. The assay accuracy, expressed as %Dev., was within ± 5.4% of the nominal concentrations. One accuracy and precision run was performed using the whole spot approach, the intra-assay precision (%CV) was within 7.1% and the accuracy was within ± 8.0% of the nominal concentrations. In contrast to the center punch approach, the whole spot approach eliminated the effect of hematocrit and high lipids on the analysis of apixaban in human DBS when an accurate sample blood volume was collected on DBS cards. Copyright © 2015 Elsevier B.V. All rights reserved.

The Rényi divergence enables accurate and precise cluster analysis for localisation microscopy.

PubMed

Staszowska, Adela D; Fox-Roberts, Patrick; Hirvonen, Liisa M; Peddie, Christopher J; Collinson, Lucy M; Jones, Gareth E; Cox, Susan

2018-06-01

Clustering analysis is a key technique for quantitatively characterising structures in localisation microscopy images. To build up accurate information about biological structures, it is critical that the quantification is both accurate (close to the ground truth) and precise (has small scatter and is reproducible). Here we describe how the Rényi divergence can be used for cluster radius measurements in localisation microscopy data. We demonstrate that the Rényi divergence can operate with high levels of background and provides results which are more accurate than Ripley's functions, Voronoi tesselation or DBSCAN. Data supporting this research will be made accessible via a web link. Software codes developed for this work can be accessed via http://coxphysics.com/Renyi_divergence_software.zip. Implemented in C ++. Correspondence and requests for materials can be also addressed to the corresponding author. adela.staszowska@gmail.com or susan.cox@kcl.ac.uk. Supplementary data are available at Bioinformatics online.

Developing and implementing a high precision setup system

NASA Astrophysics Data System (ADS)

Peng, Lee-Cheng

The demand for high-precision radiotherapy (HPRT) was first implemented in stereotactic radiosurgery using a rigid, invasive stereotactic head frame. Fractionated stereotactic radiotherapy (SRT) with a frameless device was developed along a growing interest in sophisticated treatment with a tight margin and high-dose gradient. This dissertation establishes the complete management for HPRT in the process of frameless SRT, including image-guided localization, immobilization, and dose evaluation. The most ideal and precise positioning system can allow for ease of relocation, real-time patient movement assessment, high accuracy, and no additional dose in daily use. A new image-guided stereotactic positioning system (IGSPS), the Align RT3C 3D surface camera system (ART, VisionRT), which combines 3D surface images and uses a real-time tracking technique, was developed to ensure accurate positioning at the first place. The uncertainties of current optical tracking system, which causes patient discomfort due to additional bite plates using the dental impression technique and external markers, are found. The accuracy and feasibility of ART is validated by comparisons with the optical tracking and cone-beam computed tomography (CBCT) systems. Additionally, an effective daily quality assurance (QA) program for the linear accelerator and multiple IGSPSs is the most important factor to ensure system performance in daily use. Currently, systematic errors from the phantom variety and long measurement time caused by switching phantoms were discovered. We investigated the use of a commercially available daily QA device to improve the efficiency and thoroughness. Reasonable action level has been established by considering dosimetric relevance and clinic flow. As for intricate treatments, the effect of dose deviation caused by setup errors remains uncertain on tumor coverage and toxicity on OARs. The lack of adequate dosimetric simulations based on the true treatment coordinates from the treatment planning system (TPS) has limited adaptive treatments. A reliable and accurate dosimetric simulation using TPS and in-house software in uncorrected errors has been developed. In SRT, the calculated dose deviation is compared to the original treatment dose with the dose-volume histogram to investigate the dose effect of rotational errors. In summary, this work performed a quality assessment to investigate the overall accuracy of current setup systems. To reach the ideal HPRT, the reliable dosimetric simulation, an effective daily QA program and effective, precise setup systems were developed and validated.

LC-MS/MS determination of 2-(4-((2-(2S,5R)-2-Cyano-5-ethynyl-1-pyrrolidinyl)-2-oxoethylamino)-4-methyl-1-piperidinyl)-4-pyridinecarboxylic acid (ABT-279) in dog plasma with high-throughput protein precipitation sample preparation.

PubMed

Kim, Joseph; Flick, Jeanette; Reimer, Michael T; Rodila, Ramona; Wang, Perry G; Zhang, Jun; Ji, Qin C; El-Shourbagy, Tawakol A

2007-11-01

As an effective DPP-IV inhibitor, 2-(4-((2-(2S,5R)-2-Cyano-5-ethynyl-1-pyrrolidinyl)-2-oxoethylamino)-4-methyl-1-piperidinyl)-4-pyridinecarboxylic acid (ABT-279), is an investigational drug candidate under development at Abbott Laboratories for potential treatment of type 2 diabetes. In order to support the development of ABT-279, multiple analytical methods for an accurate, precise and selective concentration determination of ABT-279 in different matrices were developed and validated in accordance with the US Food and Drug Administration Guidance on Bioanalytical Method Validation. The analytical method for ABT-279 in dog plasma was validated in parallel to other validations for ABT-279 determination in different matrices. In order to shorten the sample preparation time and increase method precision, an automated multi-channel liquid handler was used to perform high-throughput protein precipitation and all other liquid transfers. The separation was performed through a Waters YMC ODS-AQ column (2.0 x 150 mm, 5 microm, 120 A) with a mobile phase of 20 mm ammonium acetate in 20% acetonitrile at a flow rate of 0.3 mL/min. Data collection started at 2.2 min and continued for 2.0 min. The validated linear dynamic range in dog plasma was between 3.05 and 2033.64 ng/mL using a 50 microL sample volume. The achieved r(2) coefficient of determination from three consecutive runs was between 0.998625 and 0.999085. The mean bias was between -4.1 and 4.3% for all calibration standards including lower limit of quantitation. The mean bias was between -8.0 and 0.4% for the quality control samples. The precision, expressed as a coefficient of variation (CV), was < or =4.1% for all levels of quality control samples. The validation results demonstrated that the high-throughput method was accurate, precise and selective for the determination of ABT-279 in dog plasma. The validated method was also employed to support two toxicology studies. The passing rate was 100% for all 49 runs from one validation study and two toxicology studies. Copyright (c) 2007 John Wiley & Sons, Ltd.

An artificial neural network to predict resting energy expenditure in obesity.

PubMed

Disse, Emmanuel; Ledoux, Séverine; Bétry, Cécile; Caussy, Cyrielle; Maitrepierre, Christine; Coupaye, Muriel; Laville, Martine; Simon, Chantal

2017-09-01

The resting energy expenditure (REE) determination is important in nutrition for adequate dietary prescription. The gold standard i.e. indirect calorimetry is not available in clinical settings. Thus, several predictive equations have been developed, but they lack of accuracy in subjects with extreme weight including obese populations. Artificial neural networks (ANN) are useful predictive tools in the area of artificial intelligence, used in numerous clinical fields. The aim of this study was to determine the relevance of ANN in predicting REE in obesity. A Multi-Layer Perceptron (MLP) feed-forward neural network with a back propagation algorithm was created and cross-validated in a cohort of 565 obese subjects (BMI within 30-50 kg m -2 ) with weight, height, sex and age as clinical inputs and REE measured by indirect calorimetry as output. The predictive performances of ANN were compared to those of 23 predictive REE equations in the training set and in two independent sets of 100 and 237 obese subjects for external validation. Among the 23 established prediction equations for REE evaluated, the Harris & Benedict equations recalculated by Roza were the most accurate for the obese population, followed by the USA DRI, Müller and the original Harris & Benedict equations. The final 5-fold cross-validated three-layer 4-3-1 feed-forward back propagation ANN model developed in that study improved precision and accuracy of REE prediction over linear equations (precision = 68.1%, MAPE = 8.6% and RMSPE = 210 kcal/d), independently from BMI subgroups within 30-50 kg m -2 . External validation confirmed the better predictive performances of ANN model (precision = 73% and 65%, MAPE = 7.7% and 8.6%, RMSPE = 187 kcal/d and 200 kcal/d in the 2 independent datasets) for the prediction of REE in obese subjects. We developed and validated an ANN model for the prediction of REE in obese subjects that is more precise and accurate than established REE predictive equations independent from BMI subgroups. For convenient use in clinical settings, we provide a simple ANN-REE calculator available at: https://www.crnh-rhone-alpes.fr/fr/ANN-REE-Calculator. Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Precision Agriculture. Reaping the Benefits of Technological Growth. Resources in Technology.

ERIC Educational Resources Information Center

Hadley, Joel F.

1998-01-01

Technological innovations have revolutionized farming. Using precision farming techniques, farmers get an accurate picture of a field's attributes, such as soil properties, yield rates, and crop characteristics through the use of Differential Global Positioning Satellite hardware. (JOW)

LC-MS/MS assay for the quantitation of the ATR kinase inhibitor VX-970 in human plasma.

PubMed

Kiesel, Brian F; Scemama, Jonas; Parise, Robert A; Villaruz, Liza; Iffland, Andre; Doyle, Austin; Ivy, Percy; Chu, Edward; Bakkenist, Christopher J; Beumer, Jan H

2017-11-30

DNA damaging chemotherapy and radiation are widely used standard-of-care modalities for the treatment of cancer. Nevertheless, the outcome for many patients remains poor and this may be attributed, at least in part, to highly effective DNA repair mechanisms. Ataxia-telangiectasia mutated and Rad3-related (ATR) is a key regulator of the DNA-damage response (DDR) that orchestrates the repair of damaged replication forks. ATR is a serine/threonine protein kinase and ATR kinase inhibitors potentiate chemotherapy and radiation. The ATR kinase inhibitor VX-970 (NSC 780162) is in clinical development in combination with primary cytotoxic agents and as a monotherapy for tumors harboring specific mutations. We have developed and validated an LC-MS/MS assay for the sensitive, accurate and precise quantitation of VX-970 in human plasma. A dilute-and-shoot method was used to precipitate proteins followed by chromatographic separation with a Phenomenex Polar-RP 80Å (4μm, 50×2mm) column and a gradient acetonitrile-water mobile phase containing 0.1% formic acid from a 50μL sample volume. Detection was achieved using an API 4000 mass spectrometer using electrospray positive ionization mode. The assay was linear from 3 to 5,000ng/mL, proved to be accurate (94.6-104.2%) and precise (<8.4% CV), and fulfilled criteria from the FDA guidance for bioanalytical method validation. This LC-MS/MS assay will be a crucial tool in defining the clinical pharmacokinetics and pharmacology of VX-970 as it progresses through clinical development. Copyright © 2017 Elsevier B.V. All rights reserved.

Flexible taxonomic assignment of ambiguous sequencing reads

PubMed Central

2011-01-01

Background To characterize the diversity of bacterial populations in metagenomic studies, sequencing reads need to be accurately assigned to taxonomic units in a given reference taxonomy. Reads that cannot be reliably assigned to a unique leaf in the taxonomy (ambiguous reads) are typically assigned to the lowest common ancestor of the set of species that match it. This introduces a potentially severe error in the estimation of bacteria present in the sample due to false positives, since all species in the subtree rooted at the ancestor are implicitly assigned to the read even though many of them may not match it. Results We present a method that maps each read to a node in the taxonomy that minimizes a penalty score while balancing the relevance of precision and recall in the assignment through a parameter q. This mapping can be obtained in time linear in the number of matching sequences, because LCA queries to the reference taxonomy take constant time. When applied to six different metagenomic datasets, our algorithm produces different taxonomic distributions depending on whether coverage or precision is maximized. Including information on the quality of the reads reduces the number of unassigned reads but increases the number of ambiguous reads, stressing the relevance of our method. Finally, two measures of performance are described and results with a set of artificially generated datasets are discussed. Conclusions The assignment strategy of sequencing reads introduced in this paper is a versatile and a quick method to study bacterial communities. The bacterial composition of the analyzed samples can vary significantly depending on how ambiguous reads are assigned depending on the value of the q parameter. Validation of our results in an artificial dataset confirm that a combination of values of q produces the most accurate results. PMID:21211059

A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles.

PubMed

Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

2016-10-01

An accurate and precise determination of terbutaline has been carried out using a glassy carbon electrode (GCE) modified with a composite of multi-walled carbon nanotubes (MWCNTs) and nanoparticles of zirconium oxide (ZrO2NPs). Energy dispersive X-ray and scanning electron microscopic techniques were utilized for the characterization of the composite layer. Terbutaline exhibited a broad oxidation peak at 770mV on a GCE. However, MWCNTs/GCE presented an electrocatalytic effect toward the oxidation of terbutaline with a better anodic peak at 660mV. Furthermore, the electrochemical behavior of terbutaline has greatly been improved at a GCE modified with a composite of MWCNTs and nanoparticles of ZrO2. The ZrO2NPs/MWCNTs/GCE exhibited a sharp anodic wave at 645mV with a large enhancement of the current response for terbutaline. Square wave voltammetry (SWV) was performed for the determination of terbutaline at ZrO2NPs/MWCNTs/GCE. A linear plot was obtained for the current responses of terbutaline against concentrations in the range of 10-160nM yielding a detection limit of 2.25nM (based on 3Sb/m). Improved voltammetric behavior, long-time stability and good reproducibility were obtained for terbutaline at the proposed electrode. A mean recovery of 101.2% with an RSD% of 1.9 was obtained for the analysis of the drug formulation. The accurate and precise quantification of terbutaline makes the ZrO2NPs/MWCNTs/GCE system of great interest for monitoring its therapeutic use. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of the total drug-related chlorine and bromine contents in human blood plasma using high performance liquid chromatography-tandem ICP-mass spectrometry (HPLC-ICP-MS/MS).

PubMed

Klencsár, Balázs; Bolea-Fernandez, Eduardo; Flórez, María R; Balcaen, Lieve; Cuyckens, Filip; Lynen, Frederic; Vanhaecke, Frank

2016-05-30

A fast, accurate and precise method for the separation and determination of the total contents of drug-related Cl and Br in human blood plasma, based on high performance liquid chromatography - inductively coupled plasma - tandem mass spectrometry (HPLC-ICP-MS/MS), has been developed. The novel approach was proved to be a suitable alternative to the presently used standard methodology (i.e. based on a radiolabelled version of the drug molecule and radiodetection), while eliminating the disadvantages of the latter. Interference-free determination of (35)Cl has been accomplished via ICP-MS/MS using H2 as reaction gas and monitoring the (35)ClH2(+) reaction product at mass-to-charge ratio of 37. Br could be measured "on mass" at a mass-to-charge of 79. HPLC was relied on for the separation of the drug-related entities from the substantial amount of inorganic Cl. The method developed was found to be sufficiently precise (repeatability <10% RSD) and accurate (recovery between 95 and 105%) and shows a linear dynamic range (R(2)>0.990) from the limit of quantification (0.05 and 0.01 mg/L for Cl and Br in blood plasma, respectively) to at least 5 and 1mg/L for Cl and Br, respectively. Quantification via either external or internal standard calibration provides reliable results for both elements. As a proof-of-concept, human blood plasma samples from a clinical study involving a newly developed Cl- and Br-containing active pharmaceutical ingredient were analysed and the total drug exposure was successfully described. Cross-validation was achieved by comparing the results obtained on Cl- and on Br-basis. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the accuracy of direct and indirect three-dimensional digitizing processes for CAD/CAM systems - An in vitro study.

PubMed

Vecsei, Bálint; Joós-Kovács, Gellért; Borbély, Judit; Hermann, Péter

2017-04-01

To compare the accuracy (trueness, precision) of direct and indirect scanning CAD/CAM methods. A master cast with prepared abutments and edentulous parts was created from polymethyl methacrylate (PMMA). A high-resolution industrial scanner was used to create a reference model. Polyvinyl-siloxane (PVS) impressions and digital impressions with three intraoral scanners (iTero, Cerec, Trios) were made (n=10 for each) from the PMMA model. A laboratory scanner (Scan CS2) was used to digitize the sectioned cast made from the PVS impressions. The stereolithographic (STL) files of the impressions (n=40) were exported. Each file was compared to the reference using Geomagic Verify software. Six points were assigned to enable virtual calliper measurement of three distances of varying size within the arch. Methods were compared using interquartile range regression and equality-of-variance tests for precision, and mixed-effects linear regression for trueness. The mean (SD) deviation of short distance measurements from the reference value was -40.3 (79.7) μm using the indirect, and 22.3 (40.0) μm using the direct method. For the medium distance, indirect measurements deviated by 5.2 (SD: 111.3) μm, and direct measurements by 115.8 (SD: 50.7) μm, on average; for the long distance, the corresponding estimates were -325.8 (SD: 134.1) μm with the indirect, and -163.5 (SD: 145.5) μm with the direct method. Significant differences were found between the two methods (p<0.05). With both methods, the shorter the distance, the more accurate results were achieved. Virtual models obtained by digital impressions can be more accurate than their conventional counterparts. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Quantitation of isocitrate dehydrogenase (IDH)-induced D and L enantiomers of 2-hydroxyglutaric acid in biological fluids by a fully validated liquid tandem mass spectrometry method, suitable for clinical applications.

PubMed

Poinsignon, Vianney; Mercier, Lionel; Nakabayashi, Koïchi; David, Muriel D; Lalli, Alexandre; Penard-Lacronique, Virginie; Quivoron, Cyril; Saada, Véronique; De Botton, Stéphane; Broutin, Sophie; Paci, Angelo

2016-06-01

A recent update of the hallmarks of cancer includes metabolism with deregulating cellular energetics. Activating mutations in isocitrate dehydrogenase (IDH) metabolic enzymes leading to the abnormal accumulation of 2-hydroxyglutaric acid (2-HGA) have been described in hematologic malignancies and solid tumours. The diagnostic value of 2-HGA levels in blood to identify IDH mutations and its prognostic significance have been reported. We developed a liquid chromatography tandem mass spectrometry method allowing a rapid, accurate and precise simultaneous quantification of both L and D enantiomers of 2-HGA in blood samples from acute myeloid leukaemia (AML) patients, suitable for clinical applications. The method was also develop for preclinical applications from cellular and tissues samples. Deuterated (R,S)-2-hydroxyglutaric acid, disodium salt was used as internal standard and added to samples before a solid phase extraction on Phenomenex STRATA™-XL-A (200mg-3mL) 33μm cartridges. A derivatization step with (+)- o,o'-diacetyl-l-tartaric anhydride permitted to separate the two resulting diastereoisomers without chiral stationary phase, on a C18 column combined to a Xevo TQ-MS Waters mass spectrometer with an electrospray ionization (ESI) source. This method allows standard curves to be linear over the range 0.34-135.04μM with r(2) values>0.999 and low matrix effects (<11.7%). This method, which was validated according to current EMA guidelines, is accurate between-run (<3.1%) and within-run (<7.9%) and precise between-run (<5.3CV%) and within-run (<6.2CV%), and is suitable for clinical and preclinical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Laser pulsing in linear Compton scattering

DOE PAGES

Krafft, G. A.; Johnson, E.; Deitrick, K.; ...

2016-12-16

Previous work on calculating energy spectra from Compton scattering events has either neglected considering the pulsed structure of the incident laser beam, or has calculated these effects in an approximate way subject to criticism. In this paper, this problem has been reconsidered within a linear plane wave model for the incident laser beam. By performing the proper Lorentz transformation of the Klein-Nishina scattering cross section, a spectrum calculation can be created which allows the electron beam energy spread and emittance effects on the spectrum to be accurately calculated, essentially by summing over the emission of each individual electron. Such anmore » approach has the obvious advantage that it is easily integrated with a particle distribution generated by particle tracking, allowing precise calculations of spectra for realistic particle distributions in collision. The method is used to predict the energy spectrum of radiation passing through an aperture for the proposed Old Dominion University inverse Compton source. In addition, as discussed in the body of the paper, many of the results allow easy scaling estimates to be made of the expected spectrum. A misconception in the literature on Compton scattering of circularly polarized beams is corrected and recorded.« less

Improved sample preparation for GC-MS-SIM analysis of ethyl carbamate in wine.

PubMed

Nóbrega, Ian C C; Pereira, Giuliano E; Silva, Marileide; Pereira, Elainy V S; Medeiros, Marcelo M; Telles, Danuza L; Albuquerque, Eden C; Oliveira, Juliane B; Lachenmeier, Dirk W

2015-06-15

An improved sample preparation procedure for analysis of carcinogenic ethyl carbamate (EC) in wine by GC-MS-SIM is proposed. Differences over AOAC reference procedure were: (1) use of EC-d5 as internal standard instead of less similar propyl carbamate; (2) extraction by diethyl ether instead of more toxic dichloromethane, and (3) concentration by vacuum automated parallel evaporation instead of more time and work consuming rotary evaporation. Mean recovery was 104.4%, intraday precision was 6.7% (3.4 μg L(-)(1)) and 1.7% (88.5 μg L(-)(1)), regression coefficient was 0.999 in the linear working range of 3-89 μg L(-)(1), and limits of detection and quantification were 0.4 and 1.2 μg L(-)(1). Applicability was demonstrated by analysis (in triplicate) of 5 wine samples. EC concentration ranged from 5.2 ± 0.2 to 29.4 ± 1.5 μg L(-)(1). The analytical method is selective, accurate, repeatable, linear, and has similar method performance as the reference method along with the several mentioned advantages. Copyright © 2015 Elsevier Ltd. All rights reserved.

Assessment of plant species diversity based on hyperspectral indices at a fine scale.

PubMed

Peng, Yu; Fan, Min; Song, Jingyi; Cui, Tiantian; Li, Rui

2018-03-19

Fast and nondestructive approaches of measuring plant species diversity have been a subject of excessive scientific curiosity and disquiet to environmentalists and field ecologists worldwide. In this study, we measured the hyperspectral reflectances and plant species diversity indices at a fine scale (0.8 meter) in central Hunshandak Sandland of Inner Mongolia, China. The first-order derivative value (FD) at each waveband and 37 hyperspectral indices were used to assess plant species diversity. Results demonstrated that the stepwise linear regression of FD can accurately estimate the Simpson (R 2  = 0.83), Pielou (R 2  = 0.87) and Shannon-Wiener index (R 2  = 0.88). Stepwise linear regression of FD (R 2  = 0.81, R 2  = 0.82) and spectral vegetation indices (R 2  = 0.51, R 2  = 0.58) significantly predicted the Margalef and Gleason index. It was proposed that the Simpson, Pielou and Shannon-Wiener indices, which are widely used as plant species diversity indicators, can be precisely estimated through hyperspectral indices at a fine scale. This research promotes the development of methods for assessment of plant diversity using hyperspectral data.

A New Model Based on Adaptation of the External Loop to Compensate the Hysteresis of Tactile Sensors

PubMed Central

Sánchez-Durán, José A.; Vidal-Verdú, Fernando; Oballe-Peinado, Óscar; Castellanos-Ramos, Julián; Hidalgo-López, José A.

2015-01-01

This paper presents a novel method to compensate for hysteresis nonlinearities observed in the response of a tactile sensor. The External Loop Adaptation Method (ELAM) performs a piecewise linear mapping of the experimentally measured external curves of the hysteresis loop to obtain all possible internal cycles. The optimal division of the input interval where the curve is approximated is provided by the error minimization algorithm. This process is carried out off line and provides parameters to compute the split point in real time. A different linear transformation is then performed at the left and right of this point and a more precise fitting is achieved. The models obtained with the ELAM method are compared with those obtained from three other approaches. The results show that the ELAM method achieves a more accurate fitting. Moreover, the involved mathematical operations are simpler and therefore easier to implement in devices such as Field Programmable Gate Array (FPGAs) for real time applications. Furthermore, the method needs to identify fewer parameters and requires no previous selection process of operators or functions. Finally, the method can be applied to other sensors or actuators with complex hysteresis loop shapes. PMID:26501279

A comparison of viscoelastic damping models

NASA Technical Reports Server (NTRS)

Slater, Joseph C.; Belvin, W. Keith; Inman, Daniel J.

1993-01-01

Modern finite element methods (FEM's) enable the precise modeling of mass and stiffness properties in what were in the past overwhelmingly large and complex structures. These models allow the accurate determination of natural frequencies and mode shapes. However, adequate methods for modeling highly damped and high frequency dependent structures did not exist until recently. The most commonly used method, Modal Strain Energy, does not correctly predict complex mode shapes since it is based on the assumption that the mode shapes of a structure are real. Recently, many techniques have been developed which allow the modeling of frequency dependent damping properties of materials in a finite element compatible form. Two of these methods, the Golla-Hughes-McTavish method and the Lesieutre-Mingori method, model the frequency dependent effects by adding coordinates to the existing system thus maintaining the linearity of the model. The third model, proposed by Bagley and Torvik, is based on the Fractional Calculus method and requires fewer empirical parameters to model the frequency dependence at the expense of linearity of the governing equations. This work examines the Modal Strain Energy, Golla-Hughes-McTavish and Bagley and Torvik models and compares them to determine the plausibility of using them for modeling viscoelastic damping in large structures.

Methodological evaluation and comparison of five urinary albumin measurements.

PubMed

Liu, Rui; Li, Gang; Cui, Xiao-Fan; Zhang, Dong-Ling; Yang, Qing-Hong; Mu, Xiao-Yan; Pan, Wen-Jie

2011-01-01

Microalbuminuria is an indicator of kidney damage and a risk factor for the progression kidney disease, cardiovascular disease, and so on. Therefore, accurate and precise measurement of urinary albumin is critical. However, there are no reference measurement procedures and reference materials for urinary albumin. Nephelometry, turbidimetry, colloidal gold method, radioimmunoassay, and chemiluminescence immunoassay were performed for methodological evaluation, based on imprecision test, recovery rate, linearity, haemoglobin interference rate, and verified reference interval. Then we tested 40 urine samples from diabetic patients by each method, and compared the result between assays. The results indicate that nephelometry is the method with best analytical performance among the five methods, with an average intraassay coefficient of variation (CV) of 2.6%, an average interassay CV of 1.7%, a mean recovery of 99.6%, a linearity of R=1.00 from 2 to 250 mg/l, and an interference rate of <10% at haemoglobin concentrations of <1.82 g/l. The correlation (r) between assays was from 0.701 to 0.982, and the Bland-Altman plots indicated each assay provided significantly different results from each other. Nephelometry is the clinical urinary albumin method with best analytical performance in our study. © 2011 Wiley-Liss, Inc.

Linearized lattice Boltzmann method for micro- and nanoscale flow and heat transfer.

PubMed

Shi, Yong; Yap, Ying Wan; Sader, John E

2015-07-01

Ability to characterize the heat transfer in flowing gases is important for a wide range of applications involving micro- and nanoscale devices. Gas flows away from the continuum limit can be captured using the Boltzmann equation, whose analytical solution poses a formidable challenge. An efficient and accurate numerical simulation of the Boltzmann equation is thus highly desirable. In this article, the linearized Boltzmann Bhatnagar-Gross-Krook equation is used to develop a hierarchy of thermal lattice Boltzmann (LB) models based on half-space Gaussian-Hermite (GH) quadrature ranging from low to high algebraic precision, using double distribution functions. Simplified versions of the LB models in the continuum limit are also derived, and are shown to be consistent with existing thermal LB models for noncontinuum heat transfer reported in the literature. Accuracy of the proposed LB hierarchy is assessed by simulating thermal Couette flows for a wide range of Knudsen numbers. Effects of the underlying quadrature schemes (half-space GH vs full-space GH) and continuum-limit simplifications on computational accuracy are also elaborated. The numerical findings in this article provide direct evidence of improved computational capability of the proposed LB models for modeling noncontinuum flows and heat transfer at small length scales.

Design and model for the giant magnetostrictive actuator used on an electronic controlled injector

NASA Astrophysics Data System (ADS)

Xue, Guangming; Zhang, Peilin; He, Zhongbo; Li, Ben; Rong, Ce

2017-05-01

Giant magnetostrictive actuator (GMA) may be a promising candidate actuator to drive an electronic controlled injector as giant magnetostrictive material (GMM) has excellent performances as large output, fast response and high operating stability etc. To meet the driving requirement of the injector, the GMA should produce maximal shortening displacement when energized. An unbiased GMA with a ‘T’ shaped output rod is designed to reach the target. Furthermore, an open-hold-fall type driving voltage is exerted on the actuator coil to accelerate the response speed of the coil current. The actuator displacement is modeled from establishing the sub-models of coil current, magnetic field within GMM rod, magnetization and magnetostrictive strain sequentially. Two modifications are done to make the model more accurate. Firstly, consider the model fails to compute the transient-state response precisely, a dead-zone and delay links are embedded into the coil current sub-model. Secondly, as the magnetization and magnetostrictive strain sub-models just influence the change rule of the transient-state response the linear magnetostrictive strain-magnetic field sub-model is introduced. From experimental results, the modified model with linear magnetostrictive stain expression can predict the actuator displacement quite effectively.

voom: precision weights unlock linear model analysis tools for RNA-seq read counts

PubMed Central

2014-01-01

New normal linear modeling strategies are presented for analyzing read counts from RNA-seq experiments. The voom method estimates the mean-variance relationship of the log-counts, generates a precision weight for each observation and enters these into the limma empirical Bayes analysis pipeline. This opens access for RNA-seq analysts to a large body of methodology developed for microarrays. Simulation studies show that voom performs as well or better than count-based RNA-seq methods even when the data are generated according to the assumptions of the earlier methods. Two case studies illustrate the use of linear modeling and gene set testing methods. PMID:24485249

voom: Precision weights unlock linear model analysis tools for RNA-seq read counts.

PubMed

Law, Charity W; Chen, Yunshun; Shi, Wei; Smyth, Gordon K

2014-02-03

New normal linear modeling strategies are presented for analyzing read counts from RNA-seq experiments. The voom method estimates the mean-variance relationship of the log-counts, generates a precision weight for each observation and enters these into the limma empirical Bayes analysis pipeline. This opens access for RNA-seq analysts to a large body of methodology developed for microarrays. Simulation studies show that voom performs as well or better than count-based RNA-seq methods even when the data are generated according to the assumptions of the earlier methods. Two case studies illustrate the use of linear modeling and gene set testing methods.

The research of radar target tracking observed information linear filter method

NASA Astrophysics Data System (ADS)

Chen, Zheng; Zhao, Xuanzhi; Zhang, Wen

2018-05-01

Aiming at the problems of low precision or even precision divergent is caused by nonlinear observation equation in radar target tracking, a new filtering algorithm is proposed in this paper. In this algorithm, local linearization is carried out on the observed data of the distance and angle respectively. Then the kalman filter is performed on the linearized data. After getting filtered data, a mapping operation will provide the posteriori estimation of target state. A large number of simulation results show that this algorithm can solve above problems effectively, and performance is better than the traditional filtering algorithm for nonlinear dynamic systems.

Sample Introduction Using the Hildebrand Grid Nebulizer for Plasma Spectrometry

DTIC Science & Technology

1988-01-01

linear dynamic ranges, precision, and peak width were de- termined for elements in methanol and acetonitrile solutions. , (1)> The grid nebulizer was...FIA) with ICP-OES detection were evaluated. Detec- tion limits, linear dynamic ranges, precision, and peak width were de- termined for elements in...Concentration vs. Log Peak Area for Mn, 59 Cd, Zn, Au, Ni in Methanol (CMSC) 3-28 Log Concentration vs. Log Peak Area for Mn, 60 Cd, Au, Ni in

Linear Covariance Analysis for a Lunar Lander

NASA Technical Reports Server (NTRS)

Jang, Jiann-Woei; Bhatt, Sagar; Fritz, Matthew; Woffinden, David; May, Darryl; Braden, Ellen; Hannan, Michael

2017-01-01

A next-generation lunar lander Guidance, Navigation, and Control (GNC) system, which includes a state-of-the-art optical sensor suite, is proposed in a concept design cycle. The design goal is to allow the lander to softly land within the prescribed landing precision. The achievement of this precision landing requirement depends on proper selection of the sensor suite. In this paper, a robust sensor selection procedure is demonstrated using a Linear Covariance (LinCov) analysis tool developed by Draper.

Fractal geometry of music.

PubMed Central

Hsü, K J; Hsü, A J

1990-01-01

Music critics have compared Bach's music to the precision of mathematics. What "mathematics" and what "precision" are the questions for a curious scientist. The purpose of this short note is to suggest that the mathematics is, at least in part, Mandelbrot's fractal geometry and the precision is the deviation from a log-log linear plot. PMID:11607061

Precision pharmacology for Alzheimer's disease.

PubMed

Hampel, Harald; Vergallo, Andrea; Aguilar, Lisi Flores; Benda, Norbert; Broich, Karl; Cuello, A Claudio; Cummings, Jeffrey; Dubois, Bruno; Federoff, Howard J; Fiandaca, Massimo; Genthon, Remy; Haberkamp, Marion; Karran, Eric; Mapstone, Mark; Perry, George; Schneider, Lon S; Welikovitch, Lindsay A; Woodcock, Janet; Baldacci, Filippo; Lista, Simone

2018-04-01

The complex multifactorial nature of polygenic Alzheimer's disease (AD) presents significant challenges for drug development. AD pathophysiology is progressing in a non-linear dynamic fashion across multiple systems levels - from molecules to organ systems - and through adaptation, to compensation, and decompensation to systems failure. Adaptation and compensation maintain homeostasis: a dynamic equilibrium resulting from the dynamic non-linear interaction between genome, epigenome, and environment. An individual vulnerability to stressors exists on the basis of individual triggers, drivers, and thresholds accounting for the initiation and failure of adaptive and compensatory responses. Consequently, the distinct pattern of AD pathophysiology in space and time must be investigated on the basis of the individual biological makeup. This requires the implementation of systems biology and neurophysiology to facilitate Precision Medicine (PM) and Precision Pharmacology (PP). The regulation of several processes at multiple levels of complexity from gene expression to cellular cycle to tissue repair and system-wide network activation has different time delays (temporal scale) according to the affected systems (spatial scale). The initial failure might originate and occur at every level potentially affecting the whole dynamic interrelated systems within an organism. Unraveling the spatial and temporal dynamics of non-linear pathophysiological mechanisms across the continuum of hierarchical self-organized systems levels and from systems homeostasis to systems failure is key to understand AD. Measuring and, possibly, controlling space- and time-scaled adaptive and compensatory responses occurring during AD will represent a crucial step to achieve the capacity to substantially modify the disease course and progression at the best suitable timepoints, thus counteracting disrupting critical pathophysiological inputs. This approach will provide the conceptual basis for effective disease-modifying pathway-based targeted therapies. PP is based on an exploratory and integrative strategy to complex diseases such as brain proteinopathies including AD, aimed at identifying simultaneous aberrant molecular pathways and predicting their temporal impact on the systems levels. The depiction of pathway-based molecular signatures of complex diseases contributes to the accurate and mechanistic stratification of distinct subcohorts of individuals at the earliest compensatory stage when treatment intervention may reverse, stop, or delay the disease. In addition, individualized drug selection may optimize treatment safety by decreasing risk and amplitude of side effects and adverse reactions. From a methodological point of view, comprehensive "omics"-based biomarkers will guide the exploration of spatio-temporal systems-wide morpho-functional shifts along the continuum of AD pathophysiology, from adaptation to irreversible failure. The Alzheimer Precision Medicine Initiative (APMI) and the APMI cohort program (APMI-CP) have commenced to facilitate a paradigm shift towards effective drug discovery and development in AD. Copyright © 2018 Elsevier Ltd. All rights reserved.

Positioner with long travel in two dimensions

DOEpatents

Trumper, David L.; Williams, Mark E.

1997-12-23

A precision positioning system is provided which provides long travel in two of the linear dimensions, while using non-contact bearings for both a first subassembly which provides long travel in one of the linear dimension and a second subassembly which provides long travel in the second linear dimension. The first or upper subassembly is preferably a magnetic subassembly which, in addition to providing long travel, also compensates or positions in three rotary dimensions and in the third linear dimension. The second subassembly is preferably either an air bearing or magnetic subassembly and is normally used only to provide long travel. Angled surfaces may be provided for magnetic bearings and capacitive or other gap sensing probes may be mounted to the stage and ground flush with the bearing actuators to provide more precise gap measurements.

First patients treated with a 1.5 T MRI-Linac: clinical proof of concept of a high-precision, high-field MRI guided radiotherapy treatment

NASA Astrophysics Data System (ADS)

Raaymakers, B. W.; Jürgenliemk-Schulz, I. M.; Bol, G. H.; Glitzner, M.; Kotte, A. N. T. J.; van Asselen, B.; de Boer, J. C. J.; Bluemink, J. J.; Hackett, S. L.; Moerland, M. A.; Woodings, S. J.; Wolthaus, J. W. H.; van Zijp, H. M.; Philippens, M. E. P.; Tijssen, R.; Kok, J. G. M.; de Groot-van Breugel, E. N.; Kiekebosch, I.; Meijers, L. T. C.; Nomden, C. N.; Sikkes, G. G.; Doornaert, P. A. H.; Eppinga, W. S. C.; Kasperts, N.; Kerkmeijer, L. G. W.; Tersteeg, J. H. A.; Brown, K. J.; Pais, B.; Woodhead, P.; Lagendijk, J. J. W.

2017-12-01

The integration of 1.5 T MRI functionality with a radiotherapy linear accelerator (linac) has been pursued since 1999 by the UMC Utrecht in close collaboration with Elekta and Philips. The idea behind this integrated device is to offer unrivalled, online and real-time, soft-tissue visualization of the tumour and the surroundings for more precise radiation delivery. The proof of concept of this device was given in 2009 by demonstrating simultaneous irradiation and MR imaging on phantoms, since then the device has been further developed and commercialized by Elekta. The aim of this work is to demonstrate the clinical feasibility of online, high-precision, high-field MRI guidance of radiotherapy using the first clinical prototype MRI-Linac. Four patients with lumbar spine bone metastases were treated with a 3 or 5 beam step-and-shoot IMRT plan. The IMRT plan was created while the patient was on the treatment table and based on the online 1.5 T MR images; pre-treatment CT was deformably registered to the online MRI to obtain Hounsfield values. Bone metastases were chosen as the first site as these tumors can be clearly visualized on MRI and the surrounding spine bone can be detected on the integrated portal imager. This way the portal images served as an independent verification of the MRI based guidance to quantify the geometric precision of radiation delivery. Dosimetric accuracy was assessed post-treatment from phantom measurements with an ionization chamber and film. Absolute doses were found to be highly accurate, with deviations ranging from 0.0% to 1.7% in the isocenter. The geometrical, MRI based targeting as confirmed using portal images was better than 0.5 mm, ranging from 0.2 mm to 0.4 mm. In conclusion, high precision, high-field, 1.5 T MRI guided radiotherapy is clinically feasible.

The robustness and accuracy of in vivo linear wear measurements for knee prostheses based on model-based RSA.

PubMed

van Ijsseldijk, E A; Valstar, E R; Stoel, B C; Nelissen, R G H H; Reiber, J H C; Kaptein, B L

2011-10-13

Accurate in vivo measurements methods of wear in total knee arthroplasty are required for a timely detection of excessive wear and to assess new implant designs. Component separation measurements based on model-based Roentgen stereophotogrammetric analysis (RSA), in which 3-dimensional reconstruction methods are used, have shown promising results, yet the robustness of these measurements is unknown. In this study, the accuracy and robustness of this measurement for clinical usage was assessed. The validation experiments were conducted in an RSA setup with a phantom setup of a knee in a vertical orientation. 72 RSA images were created using different variables for knee orientations, two prosthesis types (fixed-bearing Duracon knee and fixed-bearing Triathlon knee) and accuracies of the reconstruction models. The measurement error was determined for absolute and relative measurements and the effect of knee positioning and true seperation distance was determined. The measurement method overestimated the separation distance with 0.1mm on average. The precision of the method was 0.10mm (2*SD) for the Duracon prosthesis and 0.20mm for the Triathlon prosthesis. A slight difference in error was found between the measurements with 0° and 10° anterior tilt. (difference=0.08mm, p=0.04). The accuracy of 0.1mm and precision of 0.2mm can be achieved for linear wear measurements based on model-based RSA, which is more than adequate for clinical applications. The measurement is robust in clinical settings. Although anterior tilt seems to influence the measurement, the size of this influence is low and clinically irrelevant. Copyright © 2011 Elsevier Ltd. All rights reserved.

Stability indicating RP-HPLC method development and validation for the simultaneous determination of aminexil and minoxidil in pharmaceutical dosage form.

PubMed

Siddiraju, S; Sahithi, M

2015-03-01

The objective of the present work is to develop stability indicating high-performance liquid chromatographic method for the simultaneous determination of aminexil and minoxidil in pharmaceutical dosage form. The chromatographic separation was achieved with BDS Hypersil C18 column (250 mm×4.6 mm×5 μ) as stationary phase and phosphate buffer and acetonitrile (78:22) as mobile phase. The method was employed by using a flow rate of 1.1 mL/min kept at 30°C. The detection wavelength was kept at 238 nm by using photo-diode array detector. The retention times of the aminexil and minoxidil were found to be 2.3 min and 3.9 min, respectively. The method developed was validated in accordance with ICH guidelines with respect to the stability indicating capacity of the method including system suitability, accuracy, precision, linearity, range, limit of detection, limit of quantification and robustness. The linearity responses of aminexil and minoxidil were found to be in the concentration ranges of 18.75-112.5 μg/mL and 25-150 μg/mL, respectively. The LOD and LOQ values for aminexil were found to be 0.31 and 0.92 μg/mL and minoxidil were found to be 0.03 and 0.10 μg/mL respectively. The percentage recoveries for both the drugs were found in the range of 98-101%. This method is accurate, precise and sensitive; hence, it can be employed for routine quality control of aminexil and minoxidil in pharmaceutical industries and drug testing laboratories. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Analysis of 2-oxothiazolidine-4-carboxylic acid by hydrophilic interaction liquid chromatography: application for ocular delivery using chitosan nanoparticles.

PubMed

Al-Kinani, Ali Athab; Naughton, Declan P; Calabrese, Gianpiero; Vangala, Anil; Smith, James R; Pierscionek, Barbara K; Alany, Raid G

2015-03-01

Oxidative damage due to low levels of glutathione (GSH) is one of the main causes of cataract formation. It has been reported that 2-oxothiazolidine-4-carboxylic acid (OTZ), a cysteine prodrug, can increase the cellular level of GSH. Currently, there is no analytical method to separate and quantify OTZ from aqueous humour samples for cataract research. The present study aims to develop and validate a hydrophilic interaction liquid chromatography (HILIC) method for the quantification of OTZ in simulated aqueous humour (SAH). The developed method was validated according to FDA guidelines. Accuracy, precision, selectivity, sensitivity, linearity, lower limit of quantification (LLOQ), lower limit of detection (LLOD) and stability were the parameters assessed in the method validation. The developed method was found to be accurate and precise with LLOQ and LLOD of 200 and 100 ng/mL, respectively; method selectivity was confirmed by the absence of any matrix interference with the analyte peak. The constructed calibration curve was linear in the range of 0.2-10 μg/mL, with a regression coefficient of 0.999. In addition, the OTZ was found to be stable in SAH after three freeze/thaw cycles. Chitosan nanoparticles loaded with OTZ were formulated by the ionic gelation method. The nanoparticles were found to be uniform in shape and well dispersed with average size of 153 nm. The in vitro release of OTZ from the nanoparticles was quantified using the developed analytical method over 96 h. Permeation of OTZ through excised bovine cornea was measured using HILIC. The lag time and the flux were 0.2 h and 3.05 μg/cm(2) h, respectively.

Novel centrifugal technology for measuring sperm concentration in the home.

PubMed

Schaff, Ulrich Y; Fredriksen, Laura L; Epperson, Jon G; Quebral, Tiffany R; Naab, Sara; Sarno, Mark J; Eisenberg, Michael L; Sommer, Greg J

2017-02-01

To evaluate the analytical performance and usability of the Trak Male Fertility Testing System, a semiquantitative (categorical) device recently US Food and Drug Administration (FDA)-cleared for measuring sperm concentration in the home by untrained users. A three-site clinical trial comparing self-reported lay user results versus reference results obtained by computer-aided semen analysis (CASA). Simulated home use environments at fertility centers and urologist offices. A total of 239 untrained users. None. Sperm concentration results reported from self-testing lay users and laboratory reference method by CASA were evaluated semiquantitatively against the device's clinical cutoffs of 15 M/mL (current World Health Organization cutoff) and 55 M/mL (associated with faster time to pregnancy). Additional reported metrics include assay linearity, precision, limit of detection, and ease-of-use ratings from lay users. Lay users achieved an accuracy (versus the reference) of 93.3% (95% confidence interval [CI] 84.1%-97.4%) for results categorized as ≤15 M/mL, 82.4% (95% CI 73.3%-88.9%) for results categorized as 15-55 M/mL, and 95.5% (95% CI 88.9%-98.2%) for results categorized as >55 M/mL. When measured quantitatively, Trak results had a strong linear correlation with CASA measurements (r = 0.99). The precision and limit of detection studies show that the device has adequate reproducibility and detection range for home use. Subjects generally rated the device as easy to use. The Trak System is an accurate tool for semiquantitatively measuring sperm concentration in the home. The system may enable screening and longitudinal assessment of sperm concentration at home. ClinicalTrials.gov identifier: NCT02475395. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Simplifying sample pretreatment: application of dried blood spot (DBS) method to blood samples, including postmortem, for UHPLC-MS/MS analysis of drugs of abuse.

PubMed

Odoardi, Sara; Anzillotti, Luca; Strano-Rossi, Sabina

2014-10-01

The complexity of biological matrices, such as blood, requires the development of suitably selective and reliable sample pretreatment procedures prior to their instrumental analysis. A method has been developed for the analysis of drugs of abuse and their metabolites from different chemical classes (opiates, methadone, fentanyl and analogues, cocaine, amphetamines and amphetamine-like substances, ketamine, LSD) in human blood using dried blood spot (DBS) and subsequent UHPLC-MS/MS analysis. DBS extraction required only 100μL of sample, added with the internal standards and then three droplets (30μL each) of this solution were spotted on the card, let dry for 1h, punched and extracted with methanol with 0.1% of formic acid. The supernatant was evaporated and the residue was then reconstituted in 100μL of water with 0.1% of formic acid and injected in the UHPLC-MS/MS system. The method was validated considering the following parameters: LOD and LOQ, linearity, precision, accuracy, matrix effect and dilution integrity. LODs were 0.05-1ng/mL and LOQs were 0.2-2ng/mL. The method showed satisfactory linearity for all substances, with determination coefficients always higher than 0.99. Intra and inter day precision, accuracy, matrix effect and dilution integrity were acceptable for all the studied substances. The addition of internal standards before DBS extraction and the deposition of a fixed volume of blood on the filter cards ensured the accurate quantification of the analytes. The validated method was then applied to authentic postmortem blood samples. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Development and Validation of Chemometric Spectrophotometric Methods for Simultaneous Determination of Simvastatin and Nicotinic Acid in Binary Combinations.

PubMed

Alahmad, Shoeb; Elfatatry, Hamed M; Mabrouk, Mokhtar M; Hammad, Sherin F; Mansour, Fotouh R

2018-01-01

The development and introduction of combined therapy represent a challenge for analysis due to severe overlapping of their UV spectra in case of spectroscopy or the requirement of a long tedious and high cost separation technique in case of chromatography. Quality control laboratories have to develop and validate suitable analytical procedures in order to assay such multi component preparations. New spectrophotometric methods for the simultaneous determination of simvastatin (SIM) and nicotinic acid (NIA) in binary combinations were developed. These methods are based on chemometric treatment of data, the applied chemometric techniques are multivariate methods including classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS). In these techniques, the concentration data matrix were prepared by using the synthetic mixtures containing SIM and NIA dissolved in ethanol. The absorbance data matrix corresponding to the concentration data matrix was obtained by measuring the absorbance at 12 wavelengths in the range 216 - 240 nm at 2 nm intervals in the zero-order. The spectrophotometric procedures do not require any separation step. The accuracy, precision and the linearity ranges of the methods have been determined and validated by analyzing synthetic mixtures containing the studied drugs. Chemometric spectrophotometric methods have been developed in the present study for the simultaneous determination of simvastatin and nicotinic acid in their synthetic binary mixtures and in their mixtures with possible excipients present in tablet dosage form. The validation was performed successfully. The developed methods have been shown to be accurate, linear, precise, and so simple. The developed methods can be used routinely for the determination dosage form. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Simultaneous determination of rutin and ascorbic acid in a sequential injection lab-at-valve system.

PubMed

Al-Shwaiyat, Mohammed Khair E A; Miekh, Yuliia V; Denisenko, Tatyana A; Vishnikin, Andriy B; Andruch, Vasil; Bazel, Yaroslav R

2018-02-05

A green, simple, accurate and highly sensitive sequential injection lab-at-valve procedure has been developed for the simultaneous determination of ascorbic acid (Asc) and rutin using 18-molybdo-2-phosphate Wells-Dawson heteropoly anion (18-MPA). The method is based on the dependence of the reaction rate between 18-MPA and reducing agents on the solution pH. Only Asc is capable of interacting with 18-MPA at pH 4.7, while at pH 7.4 the reaction with both Asc and rutin proceeds simultaneously. In order to improve the precision and sensitivity of the analysis, to minimize reagent consumption and to remove the Schlieren effect, the manifold for the sequential injection analysis was supplemented with external reaction chamber, and the reaction mixture was segmented. By the reduction of 18-MPA with reducing agents one- and two-electron heteropoly blues are formed. The fraction of one-electron heteropoly blue increases at low concentrations of the reducer. Measurement of the absorbance at a wavelength corresponding to the isobestic point allows strictly linear calibration graphs to be obtained. The calibration curves were linear in the concentration ranges of 0.3-24mgL -1 and 0.2-14mgL -1 with detection limits of 0.13mgL -1 and 0.09mgL -1 for rutin and Asc, respectively. The determination of rutin was possible in the presence of up to a 20-fold molar excess of Asc. The method was applied to the determination of Asc and rutin in ascorutin tablets with acceptable accuracy and precision (1-2%). Copyright © 2017 Elsevier B.V. All rights reserved.

A Monte Carlo Simulation Comparing the Statistical Precision of Two High-Stakes Teacher Evaluation Methods: A Value-Added Model and a Composite Measure

ERIC Educational Resources Information Center

Spencer, Bryden

2016-01-01

Value-added models are a class of growth models used in education to assign responsibility for student growth to teachers or schools. For value-added models to be used fairly, sufficient statistical precision is necessary for accurate teacher classification. Previous research indicated precision below practical limits. An alternative approach has…

Verification of spectrophotometric method for nitrate analysis in water samples

NASA Astrophysics Data System (ADS)

Kurniawati, Puji; Gusrianti, Reny; Dwisiwi, Bledug Bernanti; Purbaningtias, Tri Esti; Wiyantoko, Bayu

2017-12-01

The aim of this research was to verify the spectrophotometric method to analyze nitrate in water samples using APHA 2012 Section 4500 NO3-B method. The verification parameters used were: linearity, method detection limit, level of quantitation, level of linearity, accuracy and precision. Linearity was obtained by using 0 to 50 mg/L nitrate standard solution and the correlation coefficient of standard calibration linear regression equation was 0.9981. The method detection limit (MDL) was defined as 0,1294 mg/L and limit of quantitation (LOQ) was 0,4117 mg/L. The result of a level of linearity (LOL) was 50 mg/L and nitrate concentration 10 to 50 mg/L was linear with a level of confidence was 99%. The accuracy was determined through recovery value was 109.1907%. The precision value was observed using % relative standard deviation (%RSD) from repeatability and its result was 1.0886%. The tested performance criteria showed that the methodology was verified under the laboratory conditions.

Scaling behaviour for the water transport in nanoconfined geometries

PubMed Central

Chiavazzo, Eliodoro; Fasano, Matteo; Asinari, Pietro; Decuzzi, Paolo

2014-01-01

The transport of water in nanoconfined geometries is different from bulk phase and has tremendous implications in nanotechnology and biotechnology. Here molecular dynamics is used to compute the self-diffusion coefficient D of water within nanopores, around nanoparticles, carbon nanotubes and proteins. For almost 60 different cases, D is found to scale linearly with the sole parameter θ as D(θ)=DB[1+(DC/DB−1)θ], with DB and DC the bulk and totally confined diffusion of water, respectively. The parameter θ is primarily influenced by geometry and represents the ratio between the confined and total water volumes. The D(θ) relationship is interpreted within the thermodynamics of supercooled water. As an example, such relationship is shown to accurately predict the relaxometric response of contrast agents for magnetic resonance imaging. The D(θ) relationship can help in interpreting the transport of water molecules under nanoconfined conditions and tailoring nanostructures with precise modulation of water mobility. PMID:24699509

Advances in the development of an imaging device for plaque measurement in the area of the carotid artery.

PubMed

Ličev, Lačezar; Krumnikl, Michal; Škuta, Jaromír; Babiuch, Marek; Farana, Radim

2014-03-04

This paper describes the advances in the development and subsequent testing of an imaging device for three-dimensional ultrasound measurement of atherosclerotic plaque in the carotid artery. The embolization from the atherosclerotic carotid plaque is one of the most common causes of ischemic stroke and, therefore, we consider the measurement of the plaque as extremely important. The paper describes the proposed hardware for enhancing the standard ultrasonic probe to provide a possibility of accurate probe positioning and synchronization with the cardiac activity, allowing the precise plaque measurements that were impossible with the standard equipment. The synchronization signal is derived from the output signal of the patient monitor (electrocardiogram (ECG)), processed by a microcontroller-based system, generating the control commands for the linear motion moving the probe. The controlling algorithm synchronizes the movement with the ECG waveform to obtain clear images not disturbed by the heart activity.

An improved CS-LSSVM algorithm-based fault pattern recognition of ship power equipments.

PubMed

Yang, Yifei; Tan, Minjia; Dai, Yuewei

2017-01-01

A ship power equipments' fault monitoring signal usually provides few samples and the data's feature is non-linear in practical situation. This paper adopts the method of the least squares support vector machine (LSSVM) to deal with the problem of fault pattern identification in the case of small sample data. Meanwhile, in order to avoid involving a local extremum and poor convergence precision which are induced by optimizing the kernel function parameter and penalty factor of LSSVM, an improved Cuckoo Search (CS) algorithm is proposed for the purpose of parameter optimization. Based on the dynamic adaptive strategy, the newly proposed algorithm improves the recognition probability and the searching step length, which can effectively solve the problems of slow searching speed and low calculation accuracy of the CS algorithm. A benchmark example demonstrates that the CS-LSSVM algorithm can accurately and effectively identify the fault pattern types of ship power equipments.

Smart phone: a popular device supports amylase activity assay in fisheries research.

PubMed

Thongprajukaew, Karun; Choodum, Aree; Sa-E, Barunee; Hayee, Ummah

2014-11-15

Colourimetric determinations of amylase activity were developed based on a standard dinitrosalicylic acid (DNS) staining method, using maltose as the analyte. Intensities and absorbances of red, green and blue (RGB) were obtained with iPhone imaging and Adobe Photoshop image analysis. Correlation of green and analyte concentrations was highly significant, and the accuracy of the developed method was excellent in analytical performance. The common iPhone has sufficient imaging ability for accurate quantification of maltose concentrations. Detection limits, sensitivity and linearity were comparable to a spectrophotometric method, but provided better inter-day precision. In quantifying amylase specific activity from a commercial source (P>0.02) and fish samples (P>0.05), differences compared with spectrophotometric measurements were not significant. We have demonstrated that iPhone imaging with image analysis in Adobe Photoshop has potential for field and laboratory studies of amylase. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determination of chloramphenicol and zeranols in pig muscle by immunoaffinity column clean-up and LC-MS/MS analysis.

PubMed

Wang, Qing; Zhao, Hua; Xi, Cunxian; Wang, Guomin; Chen, Dongdong; Ding, Shijia

2014-01-01

An immunoaffinity column clean-up and LC-MS/MS method was successfully developed for simultaneous determination of chloramphenicol, zearalanone, α-zearalanol, β-zearalanol, zearalenone, α-zearalenol and β-zearalenol in pig muscle. The sample was extracted with diethyl ether after enzymatic digestion by β-glucuronidase/sulfatase. The extracted solution was evaporated to dryness and the residue was then dissolved in 1 ml of 50% acetonitrile solution. After filtration and dilution with phosphate buffer solution (PBS), the reconstituted solution was cleaned-up with an IAC-CZ immunoaffinity column and then analysed by HPLC-MS/MS. The established method were validated by linearity (r ≥ 0.9990), precision (RSD ≥ 2.9%), average recovery (74.5-105.0%) and limit of detection (0.04-0.10 μg kg(-1)). The developed method is rapid, reliable, sensitive, accurate and has good applicability for real samples.

Enantioselective supercritical fluid chromatography-tandem mass spectrometry method for simultaneous estimation of risperidone and its 9-hydroxyl metabolites in rat plasma.

PubMed

Prasad, Thatipamula R; Joseph, Siji; Kole, Prashant; Kumar, Anoop; Subramanian, Murali; Rajagopalan, Sudha; Kr, Prabhakar

2017-11-01

Objective of the current work was to develop a 'green chemistry' compliant selective and sensitive supercritical fluid chromatography-tandem mass spectrometry method for simultaneous estimation of risperidone (RIS) and its chiral metabolites in rat plasma. Methodology & results: Agilent 1260 Infinity analytical supercritical fluid chromatography system resolved RIS and its chiral metabolites within runtime of 6 min using a gradient chromatography method. Using a simple protein precipitation sample preparation followed by mass spectrometric detection achieved a sensitivity of 0.92 nM (lower limit of quantification). With linearity over four log units (0.91-7500 nM), the method was found to be selective, accurate, precise and robust. The method was validated and was successfully applied for simultaneous estimation of RIS and 9-hydroxyrisperidone metabolites (R & S individually) after intravenous and per oral administration to rats.

Simulation of Thermo-viscoplastic Behaviors for AISI 4140 Steel

NASA Astrophysics Data System (ADS)

Li, Hong-Bin; Feng, Yun-Li

2016-04-01

The thermo-viscoplastic behaviors of AISI 4140 steel are investigated over wide ranges of strain rate and deformation temperature by isothermal compression tests. Based on the experimental results, a unified viscoplastic constitutive model is proposed to describe the hot compressive deformation behaviors of the studied steel. In order to reasonably evaluate the work hardening behaviors, a strain hardening material constant (h0) is expressed as a function of deformation temperature and strain rate in the proposed constitutive model. Also, the sensitivity of initial value of internal variable s to the deformation temperature is discussed. Furthermore, it is found that the initial value of internal variable s can be expressed as a linear function of deformation temperature. Comparisons between the measured and predicted results confirm that the proposed constitutive model can give an accurate and precise estimate of the inelastic stress-strain relationships for the studied high-strength steel.

Quantitative, spectrally-resolved intraoperative fluorescence imaging

PubMed Central

Valdés, Pablo A.; Leblond, Frederic; Jacobs, Valerie L.; Wilson, Brian C.; Paulsen, Keith D.; Roberts, David W.

2012-01-01

Intraoperative visual fluorescence imaging (vFI) has emerged as a promising aid to surgical guidance, but does not fully exploit the potential of the fluorescent agents that are currently available. Here, we introduce a quantitative fluorescence imaging (qFI) approach that converts spectrally-resolved data into images of absolute fluorophore concentration pixel-by-pixel across the surgical field of view (FOV). The resulting estimates are linear, accurate, and precise relative to true values, and spectral decomposition of multiple fluorophores is also achieved. Experiments with protoporphyrin IX in a glioma rodent model demonstrate in vivo quantitative and spectrally-resolved fluorescence imaging of infiltrating tumor margins for the first time. Moreover, we present images from human surgery which detect residual tumor not evident with state-of-the-art vFI. The wide-field qFI technique has broad implications for intraoperative surgical guidance because it provides near real-time quantitative assessment of multiple fluorescent biomarkers across the operative field. PMID:23152935

Micromachined electrostatic vertical actuator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Abraham P.; Sommargren, Gary E.; McConaghy, Charles F.

A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized inmore » a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.« less

Micromachined electrostatic vertical actuator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, A.P.; Sommargren, G.E.; McConaghy, C.F.

A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized inmore » a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion, micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.« less

Information recall using relative spike timing in a spiking neural network.

PubMed

Sterne, Philip

2012-08-01

We present a neural network that is capable of completing and correcting a spiking pattern given only a partial, noisy version. It operates in continuous time and represents information using the relative timing of individual spikes. The network is capable of correcting and recalling multiple patterns simultaneously. We analyze the network's performance in terms of information recall. We explore two measures of the capacity of the network: one that values the accurate recall of individual spike times and another that values only the presence or absence of complete patterns. Both measures of information are found to scale linearly in both the number of neurons and the period of the patterns, suggesting these are natural measures of network information. We show a smooth transition from encodings that provide precise spike times to flexible encodings that can encode many scenes. This makes it plausible that many diverse tasks could be learned with such an encoding.

Practical photon number detection with electric field-modulated silicon avalanche photodiodes.

PubMed

Thomas, O; Yuan, Z L; Shields, A J

2012-01-24

Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current.

A discrete Markov metapopulation model for persistence and extinction of species.

PubMed

Thompson, Colin J; Shtilerman, Elad; Stone, Lewi

2016-09-07

A simple discrete generation Markov metapopulation model is formulated for studying the persistence and extinction dynamics of a species in a given region which is divided into a large number of sites or patches. Assuming a linear site occupancy probability from one generation to the next we obtain exact expressions for the time evolution of the expected number of occupied sites and the mean-time to extinction (MTE). Under quite general conditions we show that the MTE, to leading order, is proportional to the logarithm of the initial number of occupied sites and in precise agreement with similar expressions for continuous time-dependent stochastic models. Our key contribution is a novel application of generating function techniques and simple asymptotic methods to obtain a second order asymptotic expression for the MTE which is extremely accurate over the entire range of model parameter values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polarization Effects Aboard the Space Interferometry Mission

NASA Technical Reports Server (NTRS)

Levin, Jason; Young, Martin; Dubovitsky, Serge; Dorsky, Leonard

2006-01-01

For precision displacement measurements, laser metrology is currently one of the most accurate measurements. Often, the measurement is located some distance away from the laser source, and as a result, stringent requirements are placed on the laser delivery system with respect to the state of polarization. Such is the case with the fiber distribution assembly (FDA) that is slated to fly aboard the Space Interferometry Mission (SIM) next decade. This system utilizes a concatenated array of couplers, polarizers and lengthy runs of polarization-maintaining (PM) fiber to distribute linearly-polarized light from a single laser to fourteen different optical metrology measurement points throughout the spacecraft. Optical power fluctuations at the point of measurement can be traced back to the polarization extinction ration (PER) of the concatenated components, in conjunction with the rate of change in phase difference of the light along the slow and fast axes of the PM fiber.

Definition of a metrology servo-system for a solar imaging fourier transform spectrometer working in the far UV (IFTSUV)

NASA Astrophysics Data System (ADS)

Ruiz de Galarreta Fanju, C.; Philippon, A.; Bouzit, M.; Appourchaux, T.; Vial, J.-C.; Maillard, J.-P.; Lemaire, P.

2017-11-01

The understanding of the solar outer atmosphere requires a simultaneous combination of imaging and spectral observations concerning the far UV lines that arise from the high chromospheres up to the corona. These observations must be performed with enough spectral, spatial and temporal resolution to reveal the small atmospheric structures and to resolve the solar dynamics. An Imaging Fourier Transform Spectrometer working in the far-UV (IFTSUV, Figure 1) is an attractive instrumental solution to fulfill these requirements. However, due to the short wavelength, to preserve IFTSUV spectral precision and Signal to Noise Ratio (SNR) requires a high optical surface quality and a very accurate (linear and angular) metrology to maintain the optical path difference (OPD) during the entire scanning process by: optical path difference sampling trigger; and dynamic alignment for tip/tilt compensation (Figure 2).

Obtaining accurate amounts of mercury from mercury compounds via electrolytic methods

DOEpatents

Grossman, Mark W.; George, William A.

1987-01-01

A process for obtaining pre-determined, accurate rate amounts of mercury. In one embodiment, predetermined, precise amounts of Hg are separated from HgO and plated onto a cathode wire. The method for doing this involves dissolving a precise amount of HgO which corresponds to a pre-determined amount of Hg desired in an electrolyte solution comprised of glacial acetic acid and H.sub.2 O. The mercuric ions are then electrolytically reduced and plated onto a cathode producing the required pre-determined quantity of Hg. In another embodiment, pre-determined, precise amounts of Hg are obtained from Hg.sub.2 Cl.sub.2. The method for doing this involves dissolving a precise amount of Hg.sub.2 Cl.sub.2 in an electrolyte solution comprised of concentrated HCl and H.sub.2 O. The mercurous ions in solution are then electrolytically reduced and plated onto a cathode wire producing the required, pre-determined quantity of Hg.

Precision Timing of PSR J0437-4715: An Accurate Pulsar Distance, a High Pulsar Mass, and a Limit on the Variation of Newton's Gravitational Constant

NASA Astrophysics Data System (ADS)

Verbiest, J. P. W.; Bailes, M.; van Straten, W.; Hobbs, G. B.; Edwards, R. T.; Manchester, R. N.; Bhat, N. D. R.; Sarkissian, J. M.; Jacoby, B. A.; Kulkarni, S. R.

2008-05-01

Analysis of 10 years of high-precision timing data on the millisecond pulsar PSR J0437-4715 has resulted in a model-independent kinematic distance based on an apparent orbital period derivative, dot Pb , determined at the 1.5% level of precision (Dk = 157.0 +/- 2.4 pc), making it one of the most accurate stellar distance estimates published to date. The discrepancy between this measurement and a previously published parallax distance estimate is attributed to errors in the DE200 solar system ephemerides. The precise measurement of dot Pb allows a limit on the variation of Newton's gravitational constant, |Ġ/G| <= 23 × 10-12 yr-1. We also constrain any anomalous acceleration along the line of sight to the pulsar to |a⊙/c| <= 1.5 × 10-18 s-1 at 95% confidence, and derive a pulsar mass, mpsr = 1.76 +/- 0.20 M⊙, one of the highest estimates so far obtained.

Obtaining accurate amounts of mercury from mercury compounds via electrolytic methods

DOEpatents

Grossman, M.W.; George, W.A.

1987-07-07

A process is described for obtaining pre-determined, accurate rate amounts of mercury. In one embodiment, predetermined, precise amounts of Hg are separated from HgO and plated onto a cathode wire. The method for doing this involves dissolving a precise amount of HgO which corresponds to a pre-determined amount of Hg desired in an electrolyte solution comprised of glacial acetic acid and H[sub 2]O. The mercuric ions are then electrolytically reduced and plated onto a cathode producing the required pre-determined quantity of Hg. In another embodiment, pre-determined, precise amounts of Hg are obtained from Hg[sub 2]Cl[sub 2]. The method for doing this involves dissolving a precise amount of Hg[sub 2]Cl[sub 2] in an electrolyte solution comprised of concentrated HCl and H[sub 2]O. The mercurous ions in solution are then electrolytically reduced and plated onto a cathode wire producing the required, pre-determined quantity of Hg. 1 fig.

A Very Fast and Angular Momentum Conserving Tree Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcello, Dominic C., E-mail: dmarce504@gmail.com

There are many methods used to compute the classical gravitational field in astrophysical simulation codes. With the exception of the typically impractical method of direct computation, none ensure conservation of angular momentum to machine precision. Under uniform time-stepping, the Cartesian fast multipole method of Dehnen (also known as the very fast tree code) conserves linear momentum to machine precision. We show that it is possible to modify this method in a way that conserves both angular and linear momenta.

Relations between basic and specific motor abilities and player quality of young basketball players.

PubMed

Marić, Kristijan; Katić, Ratko; Jelicić, Mario

2013-05-01

Subjects from 5 first league clubs from Herzegovina were tested with the purpose of determining the relations of basic and specific motor abilities, as well as the effect of specific abilities on player efficiency in young basketball players (cadets). A battery of 12 tests assessing basic motor abilities and 5 specific tests assessing basketball efficiency were used on a sample of 83 basketball players. Two significant canonical correlations, i.e. linear combinations explained the relation between the set of twelve variables of basic motor space and five variables of situational motor abilities. Underlying the first canonical linear combination is the positive effect of the general motor factor, predominantly defined by jumping explosive power, movement speed of the arms, static strength of the arms and coordination, on specific basketball abilities: movement efficiency, the power of the overarm throw, shooting and passing precision, and the skill of handling the ball. The impact of basic motor abilities of precision and balance on specific abilities of passing and shooting precision and ball handling is underlying the second linear combination. The results of regression correlation analysis between the variable set of specific motor abilities and game efficiency have shown that the ability of ball handling has the largest impact on player quality in basketball cadets, followed by shooting precision and passing precision, and the power of the overarm throw.

Effect of educational preparation on the accuracy of linear growth measurement in pediatric primary care practices: results of a multicenter nursing study.

PubMed

Hench, Karen D; Shults, Justine; Benyi, Terri; Clow, Cheryl; Delaune, Joanne; Gilluly, Kathy; Johnson, Lydia; Johnson, Maryann; Rossiter, Katherine; McKnight-Menci, Heather; Shorkey, Doris; Waite, Fran; Weber, Colleen; Lipman, Terri H

2005-04-01

Consistently monitoring a child's linear growth is one of the least invasive, most sensitive tools to identify normal physiologic functioning and a healthy lifestyle. However, studies, mostly from the United Kingdom, indicate that children are frequently measured incorrectly. Inaccurate linear measurements may result in some children having undetected growth disorders whereas others with normal growth being referred for costly, unwarranted specialty evaluations. This study presents the secondary analysis of a primary study that used a randomized control study design to demonstrate that a didactic educational intervention resulted in significantly more children being measured accurately within eight pediatric practices. The secondary analysis explored the influence of the measurer's educational level on the outcome of accurate linear measurement. Results indicated that RNs were twice as likely as non-RNs to measure children accurately.

Precision Control of Multiple Quantum Cascade Lasers for Calibration Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taubman, Matthew S.; Myers, Tanya L.; Pratt, Richard M.

We present a precision, digitally interfaced current controller for quantum cascade lasers, with demonstrated DC and modulated temperature coefficients of 1- 2 ppm/ºC and 15 ppm/ºC respectively. High linearity digital to analog converters (DACs) together with an ultra-precision voltage reference, produce highly stable, precision voltages. These are in turn selected by a low charge-injection multiplexer (MUX) chip, which are then used to set output currents via a linear current regulator. The controller is operated in conjunction with a power multiplexing unit, allowing one of three lasers to be driven by the controller while ensuring protection of controller and all lasersmore » during operation, standby and switching. Simple ASCII commands sent over a USB connection to a microprocessor located in the current controller operate both the controller (via the DACs and MUX chip) and the power multiplexer.« less

Quantification of neutral human milk oligosaccharides by graphitic carbon HPLC with tandem mass spectrometry

PubMed Central

Bao, Yuanwu; Chen, Ceng; Newburg, David S.

2012-01-01

Defining the biologic roles of human milk oligosaccharides (HMOS) requires an efficient, simple, reliable, and robust analytical method for simultaneous quantification of oligosaccharide profiles from multiple samples. The HMOS fraction of milk is a complex mixture of polar, highly branched, isomeric structures that contain no intrinsic facile chromophore, making their resolution and quantification challenging. A liquid chromatography-mass spectrometry (LC-MS) method was devised to resolve and quantify 11 major neutral oligosaccharides of human milk simultaneously. Crude HMOS fractions are reduced, resolved by porous graphitic carbon HPLC with a water/acetonitrile gradient, detected by mass spectrometric specific ion monitoring, and quantified. The HPLC separates isomers of identical molecular weights allowing 11 peaks to be fully resolved and quantified by monitoring mass to charge (m/z) ratios of the deprotonated negative ions. The standard curves for each of the 11 oligosaccharides is linear from 0.078 or 0.156 to 20 μg/mL (R2 > 0.998). Precision (CV) ranges from 1% to 9%. Accuracy is from 86% to 104%. This analytical technique provides sensitive, precise, accurate quantification for each of the 11 milk oligosaccharides and allows measurement of differences in milk oligosaccharide patterns between individuals and at different stages of lactation. PMID:23068043

Object-Based Dense Matching Method for Maintaining Structure Characteristics of Linear Buildings

PubMed Central

Yan, Yiming; Qiu, Mingjie; Zhao, Chunhui; Wang, Liguo

2018-01-01

In this paper, we proposed a novel object-based dense matching method specially for the high-precision disparity map of building objects in urban areas, which can maintain accurate object structure characteristics. The proposed framework mainly includes three stages. Firstly, an improved edge line extraction method is proposed for the edge segments to fit closely to building outlines. Secondly, a fusion method is proposed for the outlines under the constraint of straight lines, which can maintain the building structural attribute with parallel or vertical edges, which is very useful for the dense matching method. Finally, we proposed an edge constraint and outline compensation (ECAOC) dense matching method to maintain building object structural characteristics in the disparity map. In the proposed method, the improved edge lines are used to optimize matching search scope and matching template window, and the high-precision building outlines are used to compensate the shape feature of building objects. Our method can greatly increase the matching accuracy of building objects in urban areas, especially at building edges. For the outline extraction experiments, our fusion method verifies the superiority and robustness on panchromatic images of different satellites and different resolutions. For the dense matching experiments, our ECOAC method shows great advantages for matching accuracy of building objects in urban areas compared with three other methods. PMID:29596393

Estimation of capsaicin through scanning densitometry and evaluation of different varieties of capsicum in India.

PubMed

Gantait, Arunava; Maji, Amal; Barman, Tapu; Banerji, Pratim; Venkatesh, P; Mukherjee, Pulok K

2012-01-01

Capsicum annuum L. (family: Solanaceae) possesses therapeutic benefits for the treatment of rheumatism, neuropathy, psoriasis, flatulence and so on. In this study fruits of four different varieties of C. annuum from four different geographical regions in India were evaluated based on their total content of capsaicin. Ethanol extracts of the fruits were used. HPTLC plates were developed in a mobile phase containing benzene, ethyl acetate and methanol (75:20:5). Densitometric scanning was performed at a wavelength of 283 nm in the absorbance mode. The calibration curve was described by the equation Y=393.587+3.836*X with a correlation coefficient (r) of 0.99890. The content of capsaicin in Nagaland, Manipur, West Bengal and Shimla varieties was found to be 3.71%, 1.78%, 0.54% and 0.06%, respectively. The developed densitometric method was found to be specific, accurate and precise. A recovery study and precision showed low levels of %RSD values. The linearity range of the curve for capsaicin was found to be 300-900 ng per spot. The limit of detection and the limit of quantification values were determined to be 31 and 94 ng, respectively, proving the sensitivity of the method. Thus the method can be used to control the total content of capsaicin on an industrial scale.

Determination of calcium, magnesium, sodium, and potassium in foodstuffs by using a microsampling flame atomic absorption spectrometric method after closed-vessel microwave digestion: method validation.

PubMed

Chekri, Rachida; Noël, Laurent; Vastel, Christelle; Millour, Sandrine; Kadar, Ali; Guérin, Thierry

2010-01-01

This paper describes a validation process in compliance with the NFIEN ISO/IEC 17025 standard for the determination of the macrominerals calcium, magnesium, sodium, and potassium in foodstuffs by microsampling with flame atomic absorption spectrometry after closed-vessel microwave digestion. The French Standards Commission (Agence Francaise de Normalisation) standards NF V03-110, NF EN V03-115, and XP T-90-210 were used to evaluate this method. The method was validated in the context of an analysis of the 1322 food samples of the second French Total Diet Study (TDS). Several performance criteria (linearity, LOQ, specificity, trueness, precision under repeatability conditions, and intermediate precision reproducibility) were evaluated. Furthermore, the method was monitored by several internal quality controls. The LOQ values obtained (25, 5, 8.3, and 8.3 mg/kg for Ca, Mg, Na, and K, respectively) were in compliance with the needs of the TDS. The method provided accurate results as demonstrated by a repeatability CV (CVr) of < 7% and a reproducibility CV (CVR) of < 12% for all the elements. Therefore, the results indicated that this method could be used in the laboratory for the routine determination of these four elements in foodstuffs with acceptable analytical performance.

Performance Equivalence and Validation of the Soleris Automated System for Quantitative Microbial Content Testing Using Pure Suspension Cultures.

PubMed

Limberg, Brian J; Johnstone, Kevin; Filloon, Thomas; Catrenich, Carl

2016-09-01

Using United States Pharmacopeia-National Formulary (USP-NF) general method <1223> guidance, the Soleris(®) automated system and reagents (Nonfermenting Total Viable Count for bacteria and Direct Yeast and Mold for yeast and mold) were validated, using a performance equivalence approach, as an alternative to plate counting for total microbial content analysis using five representative microbes: Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, and Aspergillus brasiliensis. Detection times (DTs) in the alternative automated system were linearly correlated to CFU/sample (R(2) = 0.94-0.97) with ≥70% accuracy per USP General Chapter <1223> guidance. The LOD and LOQ of the automated system were statistically similar to the traditional plate count method. This system was significantly more precise than plate counting (RSD 1.2-2.9% for DT, 7.8-40.6% for plate counts), was statistically comparable to plate counting with respect to variations in analyst, vial lots, and instruments, and was robust when variations in the operating detection thresholds (dTs; ±2 units) were used. The automated system produced accurate results, was more precise and less labor-intensive, and met or exceeded criteria for a valid alternative quantitative method, consistent with USP-NF general method <1223> guidance.

Fast in situ airborne measurement of ammonia using a mid-infrared off-axis ICOS spectrometer.

PubMed

Leen, J Brian; Yu, Xiao-Ying; Gupta, Manish; Baer, Douglas S; Hubbe, John M; Kluzek, Celine D; Tomlinson, Jason M; Hubbell, Mike R

2013-09-17

A new ammonia (NH3) analyzer was developed based on off-axis integrated cavity output spectroscopy. Its feasibility was demonstrated by making tropospheric measurements in flights aboard the Department of Energy Gulfstream-1 aircraft. The ammonia analyzer consists of an optical cell, quantum-cascade laser, gas sampling system, control and data acquisition electronics, and analysis software. The NH3 mixing ratio is determined from high-resolution absorption spectra obtained by tuning the laser wavelength over the NH3 fundamental vibration band near 9.67 μm. Excellent linearity is obtained over a wide dynamic range (0-101 ppbv) with a response rate (1/e) of 2 Hz and a precision of ±90 pptv (1σ in 1 s). Two research flights were conducted over the Yakima Valley in Washington State. In the first flight, the ammonia analyzer was used to identify signatures of livestock from local dairy farms with high vertical and spatial resolution under low wind and calm atmospheric conditions. In the second flight, the analyzer captured livestock emission signals under windy conditions. Our results demonstrate that this new ammonia spectrometer is capable of providing fast, precise, and accurate in situ observations of ammonia aboard airborne platforms to advance our understanding of atmospheric compositions and aerosol formation.

Stability-indicating UPLC method for determination of Valsartan and their degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms.

PubMed

Krishnaiah, Ch; Reddy, A Raghupathi; Kumar, Ramesh; Mukkanti, K

2010-11-02

A simple, precise, accurate stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the quantitative determination of purity of Valsartan drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. The method was developed using Waters Aquity BEH C18 (100 mm x 2.1 mm, 1.7 microm) column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 225 nm, the run time was within 9.5 min, which Valsartan and its seven impurities were well separated. Valsartan was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Valsartan was found to degrade significantly in acid and oxidative stress conditions and stable in base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per international conference on harmonization (ICH) guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of Valsartan in pharmaceutical dosage forms.

High-bandwidth and flexible tracking control for precision motion with application to a piezo nanopositioner.

PubMed

Feng, Zhao; Ling, Jie; Ming, Min; Xiao, Xiao-Hui

2017-08-01

For precision motion, high-bandwidth and flexible tracking are the two important issues for significant performance improvement. Iterative learning control (ILC) is an effective feedforward control method only for systems that operate strictly repetitively. Although projection ILC can track varying references, the performance is still limited by the fixed-bandwidth Q-filter, especially for triangular waves tracking commonly used in a piezo nanopositioner. In this paper, a wavelet transform-based linear time-varying (LTV) Q-filter design for projection ILC is proposed to compensate high-frequency errors and improve the ability to tracking varying references simultaneously. The LVT Q-filter is designed based on the modulus maximum of wavelet detail coefficients calculated by wavelet transform to determine the high-frequency locations of each iteration with the advantages of avoiding cross-terms and segmenting manually. The proposed approach was verified on a piezo nanopositioner. Experimental results indicate that the proposed approach can locate the high-frequency regions accurately and achieve the best performance under varying references compared with traditional frequency-domain and projection ILC with a fixed-bandwidth Q-filter, which validates that through implementing the LTV filter on projection ILC, high-bandwidth and flexible tracking can be achieved simultaneously by the proposed approach.

ELM: an Algorithm to Estimate the Alpha Abundance from Low-resolution Spectra

NASA Astrophysics Data System (ADS)

Bu, Yude; Zhao, Gang; Pan, Jingchang; Bharat Kumar, Yerra

2016-01-01

We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods.

Extractive Spectrophotometric Determination of Nortriptyline Hydrochloride Using Sudan II, IV and Black B.

PubMed

Amin, A S; Saleh, H M

2017-08-17

A simple spectrophotometric methods has been developed for the determination of nortriptyline hydrochloride in pure and in pharmaceuticalformulations based on the formation of ion-pair complexes with sudun II (S II ), sudan (IV) (S IV ) and sudan black B (S BB ). The selectivity of the method was improved through extraction with chloroform. The optimum conditions for complete extracted colour development were assessed. The absorbance measurements were made at 534, 596 and 649 nm for S II , S IV and S BB complexes, respectively. The calibration graph was linear in the ranges 0.5- 280. 0.5- 37.5 and 0.5 - 31.0 μg ml -1 of the drug usiny the same reagents, respectively. The precision of the procedure was checked by calculating the relative standard deviation of ten replicate determinations on 15 μg ml -1 of nortriptyline HCI and was found to be 1.7, 1.3 and 1.55% using S II , S IV , and S BB complexes, respectively. The molar absorptivity and Sandell sensitivity for each ion-pair were calculated. The proposed methods were successfully applied to the deterniination of pure nortriptyline HCI and in pharmaceutical formulations, and the results demonstrated that the method is equally accurate, precise and reproducible as the official method.

A robust statistical estimation (RoSE) algorithm jointly recovers the 3D location and intensity of single molecules accurately and precisely

NASA Astrophysics Data System (ADS)

Mazidi, Hesam; Nehorai, Arye; Lew, Matthew D.

2018-02-01

In single-molecule (SM) super-resolution microscopy, the complexity of a biological structure, high molecular density, and a low signal-to-background ratio (SBR) may lead to imaging artifacts without a robust localization algorithm. Moreover, engineered point spread functions (PSFs) for 3D imaging pose difficulties due to their intricate features. We develop a Robust Statistical Estimation algorithm, called RoSE, that enables joint estimation of the 3D location and photon counts of SMs accurately and precisely using various PSFs under conditions of high molecular density and low SBR.

Improved measurement linearity and precision for AMCW time-of-flight range imaging cameras.

PubMed

Payne, Andrew D; Dorrington, Adrian A; Cree, Michael J; Carnegie, Dale A

2010-08-10

Time-of-flight range imaging systems utilizing the amplitude modulated continuous wave (AMCW) technique often suffer from measurement nonlinearity due to the presence of aliased harmonics within the amplitude modulation signals. Typically a calibration is performed to correct these errors. We demonstrate an alternative phase encoding approach that attenuates the harmonics during the sampling process, thereby improving measurement linearity in the raw measurements. This mitigates the need to measure the system's response or calibrate for environmental changes. In conjunction with improved linearity, we demonstrate that measurement precision can also be increased by reducing the duty cycle of the amplitude modulated illumination source (while maintaining overall illumination power).

Comparison of linear and nonlinear implementation of the compartmental tissue uptake model for dynamic contrast-enhanced MRI.

PubMed

Kallehauge, Jesper F; Sourbron, Steven; Irving, Benjamin; Tanderup, Kari; Schnabel, Julia A; Chappell, Michael A

2017-06-01

Fitting tracer kinetic models using linear methods is much faster than using their nonlinear counterparts, although this comes often at the expense of reduced accuracy and precision. The aim of this study was to derive and compare the performance of the linear compartmental tissue uptake (CTU) model with its nonlinear version with respect to their percentage error and precision. The linear and nonlinear CTU models were initially compared using simulations with varying noise and temporal sampling. Subsequently, the clinical applicability of the linear model was demonstrated on 14 patients with locally advanced cervical cancer examined with dynamic contrast-enhanced magnetic resonance imaging. Simulations revealed equal percentage error and precision when noise was within clinical achievable ranges (contrast-to-noise ratio >10). The linear method was significantly faster than the nonlinear method, with a minimum speedup of around 230 across all tested sampling rates. Clinical analysis revealed that parameters estimated using the linear and nonlinear CTU model were highly correlated (ρ ≥ 0.95). The linear CTU model is computationally more efficient and more stable against temporal downsampling, whereas the nonlinear method is more robust to variations in noise. The two methods may be used interchangeably within clinical achievable ranges of temporal sampling and noise. Magn Reson Med 77:2414-2423, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

High precision, rapid laser hole drilling

DOEpatents

Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.

2007-03-20

A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.

High precision, rapid laser hole drilling

DOEpatents

Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.

2005-03-08

A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.

High precision, rapid laser hole drilling

DOEpatents

Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.

2013-04-02

A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.

Delay times of a LiDAR-guided precision sprayer control system

USDA-ARS?s Scientific Manuscript database

Accurate flow control systems in triggering sprays against detected targets are needed for precision variable-rate sprayer development. System delay times due to the laser-sensor data buffer, software operation, and hydraulic-mechanical component response were determined for a control system used fo...

Integrated Analytic and Linearized Inverse Kinematics for Precise Full Body Interactions

NASA Astrophysics Data System (ADS)

Boulic, Ronan; Raunhardt, Daniel

Despite the large success of games grounded on movement-based interactions the current state of full body motion capture technologies still prevents the exploitation of precise interactions with complex environments. This paper focuses on ensuring a precise spatial correspondence between the user and the avatar. We build upon our past effort in human postural control with a Prioritized Inverse Kinematics framework. One of its key advantage is to ease the dynamic combination of postural and collision avoidance constraints. However its reliance on a linearized approximation of the problem makes it vulnerable to the well-known full extension singularity of the limbs. In such context the tracking performance is reduced and/or less believable intermediate postural solutions are produced. We address this issue by introducing a new type of analytic constraint that smoothly integrates within the prioritized Inverse Kinematics framework. The paper first recalls the background of full body 3D interactions and the advantages and drawbacks of the linearized IK solution. Then the Flexion-EXTension constraint (FLEXT in short) is introduced for the partial position control of limb-like articulated structures. Comparative results illustrate the interest of this new type of integrated analytical and linearized IK control.

Effect of cleaning status on accuracy and precision of oxygen flowmeters of various ages.

PubMed

Fissekis, Stephanie; Hodgson, David S; Bello, Nora M

2017-07-01

To evaluate oxygen flowmeters for accuracy and precision, assess the effects of cleaning and assess conformity to the American Society for Testing Materials (ASTM) standards. Experimental study. The flow of oxygen flowmeters from 31 anesthesia machines aged 1-45 years was measured before and after cleaning using a volumetric flow analyzer set at 0.5, 1.0, 2.0, 3.0, and 4.0 L minute -1 . A general linear mixed models approach was used to assess flow accuracy and precision. Flowmeters 1 year of age delivered accurate mean oxygen flows at all settings regardless of cleaning status. Flowmeters ≥5 years of age underdelivered at flows of 3.0 and 4.0 L minute -1 . Flowmeters ≥12 years underdelivered at flows of 2.0, 3.0 and 4.0 L minute -1 prior to cleaning. There was no evidence of any beneficial effect of cleaning on accuracy of flowmeters 5-12 years of age (p > 0.22), but the accuracy of flowmeters ≥15 years of age was improved by cleaning (p < 0.05). Regardless of age, cleaning increased precision, decreasing flow variability by approximately 17%. Nine of 31 uncleaned flowmeters did not meet ASTM standards. After cleaning, a different set of nine flowmeters did not meet standards, including three that had met standards prior to cleaning. Older flowmeters were more likely to underdeliver oxygen, especially at higher flows. Regardless of age, cleaning decreased flow variability, improving precision. However, flowmeters still may fail to meet ASTM standards, regardless of cleaning status. Cleaning anesthesia machine oxygen flowmeters improved precision for all tested machines and partially corrected inaccuracies in flowmeters ≥15 years old. A notable proportion of flowmeters did not meet ASTM standards. Cleaning did not ensure that they subsequently conformed to ASTM standards. We recommend annual flow output validation to identify whether flowmeters are acceptable for continued clinical use. Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

Improving precise positioning of surgical robotic instruments by a three-side-view presentation system on telesurgery.

PubMed

Hori, Kenta; Kuroda, Tomohiro; Oyama, Hiroshi; Ozaki, Yasuhiko; Nakamura, Takehiko; Takahashi, Takashi

2005-12-01

For faultless collaboration among the surgeon, surgical staffs, and surgical robots in telesurgery, communication must include environmental information of the remote operating room, such as behavior of robots and staffs, vital information of a patient, named supporting information, in addition to view of surgical field. "Surgical Cockpit System, " which is a telesurgery support system that has been developed by the authors, is mainly focused on supporting information exchange between remote sites. Live video presentation is important technology for Surgical Cockpit System. Visualization method to give precise location/posture of surgical instruments is indispensable for accurate control and faultless operation. In this paper, the authors propose three-side-view presentation method for precise location/posture control of surgical instruments in telesurgery. The experimental results show that the proposed method improved accurate positioning of a telemanipulator.

High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn

PubMed Central

Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

2017-01-01

Context: Sea buckthorn (Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. Objective: A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Settings and design: Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. Materials and Methods: The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. Statistical performances: The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes (R2 > 0.9997). Results: The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. Conclusions: The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. SUMMARY Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically active components in traditional Chinese medicine and its preparation Abbreviation used: PR: protocatechuic acid, RU: rutin, QU: quercetin, KA: kaempferol, IS: isorhamnetin, HPLC: high-performance liquid chromatography, HPLC-DAD: high performance liquid chromatographydiode array detector, LOD: linearity and limit of detection, LOQ: limit of quantitation, RSD: relative standard deviation PMID:28216897

THE PHOTOMETRIC AND KINEMATIC STRUCTURE OF FACE-ON DISK GALAXIES. III. KINEMATIC INCLINATIONS FROM H{alpha} VELOCITY FIELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, David R.; Bershady, Matthew A., E-mail: david.andersen@nrc-cnrc.gc.ca, E-mail: mab@astro.wisc.edu

2013-05-01

Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained H{alpha} velocity fields of 39 nearly face-on disks at echelle resolutions. High-quality, uniform kinematic data and a new modeling technique enabled us to derive accurate and precise kinematic inclinations with mean i{sub kin} = 23 Degree-Sign for 90% of these galaxies. Modeling the kinematic data as single, inclined disks in circular rotation improves upon the traditional tilted-ring method. We measure kinematic inclinations with a precision in sin i of 25% at 20 Degree-Sign and 6% at 30 Degree-Sign . Kinematic inclinations are consistent with photometricmore » and inverse Tully-Fisher inclinations when the sample is culled of galaxies with kinematic asymmetries, for which we give two specific prescriptions. Kinematic inclinations can therefore be used in statistical ''face-on'' Tully-Fisher studies. A weighted combination of multiple, independent inclination measurements yield the most precise and accurate inclination. Combining inverse Tully-Fisher inclinations with kinematic inclinations yields joint probability inclinations with a precision in sin i of 10% at 15 Degree-Sign and 5% at 30 Degree-Sign . This level of precision makes accurate mass decompositions of galaxies possible even at low inclination. We find scaling relations between rotation speed and disk-scale length identical to results from more inclined samples. We also observe the trend of more steeply rising rotation curves with increased rotation speed and light concentration. This trend appears to be uncorrelated with disk surface brightness.« less

Accuracy of linear drilling in temporal bone using drill press system for minimally invasive cochlear implantation

PubMed Central

Balachandran, Ramya; Labadie, Robert F.

2015-01-01

Purpose A minimally invasive approach for cochlear implantation involves drilling a narrow linear path through the temporal bone from the skull surface directly to the cochlea for insertion of the electrode array without the need for an invasive mastoidectomy. Potential drill positioning errors must be accounted for to predict the effectiveness and safety of the procedure. The drilling accuracy of a system used for this procedure was evaluated in bone surrogate material under a range of clinically relevant parameters. Additional experiments were performed to isolate the error at various points along the path to better understand why deflections occur. Methods An experimental setup to precisely position the drill press over a target was used. Custom bone surrogate test blocks were manufactured to resemble the mastoid region of the temporal bone. The drilling error was measured by creating divots in plastic sheets before and after drilling and using a microscope to localize the divots. Results The drilling error was within the tolerance needed to avoid vital structures and ensure accurate placement of the electrode; however, some parameter sets yielded errors that may impact the effectiveness of the procedure when combined with other error sources. The error increases when the lateral stage of the path terminates in an air cell and when the guide bushings are positioned further from the skull surface. At contact points due to air cells along the trajectory, higher errors were found for impact angles of 45° and higher as well as longer cantilevered drill lengths. Conclusion The results of these experiments can be used to define more accurate and safe drill trajectories for this minimally invasive surgical procedure. PMID:26183149

Accuracy of linear drilling in temporal bone using drill press system for minimally invasive cochlear implantation.

PubMed

Dillon, Neal P; Balachandran, Ramya; Labadie, Robert F

2016-03-01

A minimally invasive approach for cochlear implantation involves drilling a narrow linear path through the temporal bone from the skull surface directly to the cochlea for insertion of the electrode array without the need for an invasive mastoidectomy. Potential drill positioning errors must be accounted for to predict the effectiveness and safety of the procedure. The drilling accuracy of a system used for this procedure was evaluated in bone surrogate material under a range of clinically relevant parameters. Additional experiments were performed to isolate the error at various points along the path to better understand why deflections occur. An experimental setup to precisely position the drill press over a target was used. Custom bone surrogate test blocks were manufactured to resemble the mastoid region of the temporal bone. The drilling error was measured by creating divots in plastic sheets before and after drilling and using a microscope to localize the divots. The drilling error was within the tolerance needed to avoid vital structures and ensure accurate placement of the electrode; however, some parameter sets yielded errors that may impact the effectiveness of the procedure when combined with other error sources. The error increases when the lateral stage of the path terminates in an air cell and when the guide bushings are positioned further from the skull surface. At contact points due to air cells along the trajectory, higher errors were found for impact angles of [Formula: see text] and higher as well as longer cantilevered drill lengths. The results of these experiments can be used to define more accurate and safe drill trajectories for this minimally invasive surgical procedure.

Development and validation of an UHPLC-LTQ-Orbitrap MS method for non-anthocyanin flavonoids quantification in Euterpe oleracea juice.

PubMed

Dias, Aécio L S; Rozet, Eric; Larondelle, Yvan; Hubert, Philippe; Rogez, Hervé; Quetin-Leclercq, Joëlle

2013-11-01

Euterpe oleracea fruits have gained much attention because of their phenolic constituents that have shown potential health benefits. The aim of this work was to quantify the major non-anthocyanin flavonoids (NAF) in the fruit juice by an accurate method coupling ultra-high pressure liquid chromatography with a linear ion trap-high resolution Orbitrap mass spectrometry system (UHPLC-LTQ-Orbitrap MS). Fruits were processed to juice, and then the juice was lyophilized and defatted. The residue was then extracted in the presence of methanol by sonication. The extraction time was optimized and recovery rates of the extraction were >90%. The extracts were dried and solubilized again in 40% MeOH, which showed the best compromise for MS detection. For the UHPLC quantification, a HSS C18 column (1.8 μm) was used with a gradient elution of methanol and water both with 0.1% formic acid. Total error and accuracy profiles were used as validation criteria. Seven compounds and their isomers were successfully separated, including the major NAF. Calibration in the matrix was found to be more accurate than calibration without matrix. Trueness (<15% relative bias), repeatability, and intermediate precision (<13% RSD), selectivity, response function, linearity, LOD (ranged from 0.04 to 0.81 μg/mL) and LOQ (0.15-5.78 μg/mL) for 12 compounds were evaluated and the quantification method was validated. Its applicability was demonstrated on real samples from different suppliers. Their qualitative and quantitative profiles were similar and some compounds were for the first time quantified. In addition, eriodictyol was identified for the first time in this fruit along with five other flavonoids for which possible structures were proposed.

Simultaneous measurement of monocomponent droplet temperature/refractive index, size and evaporation rate with phase rainbow refractometry

NASA Astrophysics Data System (ADS)

Wu, Yingchun; Crua, Cyril; Li, Haipeng; Saengkaew, Sawitree; Mädler, Lutz; Wu, Xuecheng; Gréhan, Gérard

2018-07-01

The accurate measurements of droplet temperature, size and evaporation rate are of great importance to characterize the heat and mass transfer during evaporation/condensation processes. The nanoscale size change of a micron-sized droplet exactly describes its transient mass transfer, but is difficult to measure because it is smaller than the resolutions of current size measurement techniques. The Phase Rainbow Refractometry (PRR) technique is developed and applied to measure droplet temperature, size and transient size changes and thereafter evaporation rate simultaneously. The measurement principle of PRR is theoretically derived, and it reveals that the phase shift of the time-resolved ripple structures linearly depends on, and can directly yield, nano-scale size changes of droplets. The PRR technique is first verified through the simulation of rainbows of droplets with changing size, and results show that PRR can precisely measure droplet refractive index, absolute size, as well as size change with absolute and relative errors within several nanometers and 0.6%, respectively, and thus PRR permits accurate measurements of transient droplet evaporation rates. The evaporations of flowing single n-nonane droplet and mono-dispersed n-heptane droplet stream are investigated by two PRR systems with a high speed linear CCD and a low speed array CCD, respectively. Their transient evaporation rates are experimentally determined and quantitatively agree well with the theoretical values predicted by classical Maxwell and Stefan-Fuchs models. With the demonstration of evaporation rate measurement of monocomponent droplet in this work, PRR is an ideal tool for measurements of transient droplet evaporation/condensation processes, and can be extended to multicomponent droplets in a wide range of industrially-relevant applications.

Potential pitfalls when denoising resting state fMRI data using nuisance regression.

PubMed

Bright, Molly G; Tench, Christopher R; Murphy, Kevin

2017-07-01

In resting state fMRI, it is necessary to remove signal variance associated with noise sources, leaving cleaned fMRI time-series that more accurately reflect the underlying intrinsic brain fluctuations of interest. This is commonly achieved through nuisance regression, in which the fit is calculated of a noise model of head motion and physiological processes to the fMRI data in a General Linear Model, and the "cleaned" residuals of this fit are used in further analysis. We examine the statistical assumptions and requirements of the General Linear Model, and whether these are met during nuisance regression of resting state fMRI data. Using toy examples and real data we show how pre-whitening, temporal filtering and temporal shifting of regressors impact model fit. Based on our own observations, existing literature, and statistical theory, we make the following recommendations when employing nuisance regression: pre-whitening should be applied to achieve valid statistical inference of the noise model fit parameters; temporal filtering should be incorporated into the noise model to best account for changes in degrees of freedom; temporal shifting of regressors, although merited, should be achieved via optimisation and validation of a single temporal shift. We encourage all readers to make simple, practical changes to their fMRI denoising pipeline, and to regularly assess the appropriateness of the noise model used. By negotiating the potential pitfalls described in this paper, and by clearly reporting the details of nuisance regression in future manuscripts, we hope that the field will achieve more accurate and precise noise models for cleaning the resting state fMRI time-series. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Stable clustering and the resolution of dissipationless cosmological N-body simulations

NASA Astrophysics Data System (ADS)

Benhaiem, David; Joyce, Michael; Sylos Labini, Francesco

2017-10-01

The determination of the resolution of cosmological N-body simulations, I.e. the range of scales in which quantities measured in them represent accurately the continuum limit, is an important open question. We address it here using scale-free models, for which self-similarity provides a powerful tool to control resolution. Such models also provide a robust testing ground for the so-called stable clustering approximation, which gives simple predictions for them. Studying large N-body simulations of such models with different force smoothing, we find that these two issues are in fact very closely related: our conclusion is that the accuracy of two-point statistics in the non-linear regime starts to degrade strongly around the scale at which their behaviour deviates from that predicted by the stable clustering hypothesis. Physically the association of the two scales is in fact simple to understand: stable clustering fails to be a good approximation when there are strong interactions of structures (in particular merging) and it is precisely such non-linear processes which are sensitive to fluctuations at the smaller scales affected by discretization. Resolution may be further degraded if the short distance gravitational smoothing scale is larger than the scale to which stable clustering can propagate. We examine in detail the very different conclusions of studies by Smith et al. and Widrow et al. and find that the strong deviations from stable clustering reported by these works are the results of over-optimistic assumptions about scales resolved accurately by the measured power spectra, and the reliance on Fourier space analysis. We emphasize the much poorer resolution obtained with the power spectrum compared to the two-point correlation function.