scholarly journals Review and Mechanism of the Thickness Effect of Solid Dielectrics

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2473
Author(s):  
Liang Zhao ◽  
Chun Liang Liu
Keyword(s):  
Physical Mechanism ◽  
Breakdown Strength ◽  
Power Relation ◽  
Thickness Effect ◽  
Power Exponent ◽  
Relative Standard Error ◽  
Dielectric Thickness ◽  
Relative Standard ◽  
Different Types ◽  
Solid Dielectrics

The thickness effect of solid dielectrics means the relation between the electric breakdown strength (EBD) and the dielectric thickness (d). By reviewing different types of expressions of EBD on d, it is found that the minus power relation (EBD = E1d−a) is supported by plenty of experimental results. The physical mechanism responsible for the minus power relation of the thickness effect is reviewed and improved. In addition, it is found that the physical meaning of the power exponent a is approximately the relative standard error of the EBD distributions in perspective of the Weibull distribution. In the end, the factors influencing the power exponent a are discussed.

scholarly journals Lidar arc scan uncertainty reduction through scanning geometry optimization

2016 ◽  
Vol 9 (4) ◽  
pp. 1653-1669 ◽  
Author(s):  
Hui Wang ◽  
Rebecca J. Barthelmie ◽  
Sara C. Pryor ◽  
Gareth. Brown
Keyword(s):  
Theoretical Model ◽  
Wind Speed ◽  
Wind Energy ◽  
Turbulence Intensity ◽  
Wind Direction ◽  
Energy Production ◽  
Elevation Angle ◽  
Relative Standard Error ◽  
Power Performance ◽  
Relative Standard

Abstract. Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction). Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation). This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production prediction. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation.

scholarly journals Population Pharmacokinetics of Fluconazole in Young Infants

2008 ◽  
Vol 52 (11) ◽  
pp. 4043-4049 ◽  
Author(s):  
K. C. Wade ◽  
D. Wu ◽  
D. A. Kaufman ◽  
R. M. Ward ◽  
D. K. Benjamin ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Relative Standard Error ◽  
Data Set ◽  
Mixed Effect ◽  
Young Infants ◽  
Relative Standard ◽  
Population Pk ◽  
The Impact

ABSTRACT Fluconazole is being increasingly used to prevent and treat invasive candidiasis in neonates, yet dosing is largely empirical due to the lack of adequate pharmacokinetic (PK) data. We performed a multicenter population PK study of fluconazole in 23- to 40-week-gestation infants less than 120 days of age. We developed a population PK model using nonlinear mixed effect modeling (NONMEM) with the NONMEM algorithm. Covariate effects were predefined and evaluated based on estimation precision and clinical significance. We studied fluconazole PK in 55 infants who at enrollment had a median (range) weight of 1.02 (0.440 to 7.125) kg, a gestational age at birth (BGA) of 26 (23 to 40) weeks, and a postnatal age (PNA) of 2.3 (0.14 to 12.6) weeks. The final data set contained 357 samples; 217/357 (61%) were collected prospectively at prespecified time intervals, and 140/357 (39%) were scavenged from discarded clinical specimens. Fluconazole population PK was best described by a one-compartment model with covariates normalized to median values. The population mean clearance (CL) can be derived for this population by the equation CL (liter/h) equals 0.015 · (weight/1)0.75 · (BGA/26)1.739 · (PNA/2)0.237 · serum creatinine (SCRT)−4.896 (when SCRT is >1.0 mg/dl), and using a volume of distribution (V) (liter) of 1.024 · (weight/1). The relative standard error around the fixed effects point estimates ranged from 3 to 24%. CL doubles between birth and 28 days of age from 0.008 to 0.016 and from 0.010 to 0.022 liter/kg/h for typical 24- and 32-week-gestation infants, respectively. This population PK model of fluconazole discriminated the impact of BGA, PNA, and creatinine on drug CL. Our data suggest that dosing in young infants will require adjustment for BGA and PNA to achieve targeted systemic drug exposures.

Determination of total antioxidant capacity of milk by CUPRAC and ABTS methods with separate characterisation of milk protein fractions

2015 ◽  
Vol 82 (2) ◽  
pp. 177-184 ◽  
Author(s):  
Sema Demirci Çekiç ◽  
Aslı Demir ◽  
Kevser Sözgen Başkan ◽  
Esma Tütem ◽  
Reşat Apak
Keyword(s):  
Antioxidant Capacity ◽  
Total Antioxidant Capacity ◽  
Milk Protein ◽  
Skim Milk ◽  
Protein Fractions ◽  
Relative Standard Error ◽  
Antioxidant Power ◽  
Antioxidant Capacities ◽  
Relative Standard ◽  
Total Antioxidant

Most milk-applied antioxidant assays in literature are based on the isolation and quantification of individual antioxidative compounds, whereas total antioxidant capacity (TAC) gives a more holistic picture due to cooperative action of antioxidants. Recently, the cupric reducing antioxidant capacity (CUPRAC) method has been modified to measure the antioxidant capacities of thiol-containing proteins, where the classical ammonium acetate buffer – that may otherwise precipitate proteins– was replaced with concentrated urea buffer (able to expose embedded thiol groups of proteins to oxidative attack) adjusted to pH 7.0. Thus, antioxidant capacity of milk was investigated with two competing TAC assays, namely CUPRAC and ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid))/persulphate, because only these assays were capable of evaluating protein contribution to the observed TAC value. As milk fat caused turbidity, experiments were carried out with skim milk or defatted milk samples. To determine TAC, modified CUPRAC method was applied to whole milk, separated and redissolved protein fractions, and the remaining liquid phase after necessary operations. Both TAC methods were investigated for their dilution sensitivity and antioxidant power assessment of separate milk fractions such as casein and whey. Proteins like β-lactoglobulin and casein (but not simple thiols) exhibited enhanced CUPRAC reactivity with surfactant (SDS) addition. Addition of milk protein fractions to whole skim milk produced significant ‘negative-biased’ deviations (up to −26% relative standard error) from TAC absorbance additivity in the application of the ABTS method, as opposed to that of the CUPRAC method less affected by chemical deviations from Beer's law thereby producing much smaller deviations from additivity (i.e. the property of additivity is valid when the measured TAC of a mixture is equal to the sum of individual antioxidant capacities of its constituents).

scholarly journals Initial effective stress controls the nature of earthquakes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
François X. Passelègue ◽  
Michelle Almakari ◽  
Pierre Dublanchet ◽  
Fabian Barras ◽  
Jérôme Fortin ◽  
...  
Keyword(s):  
Effective Stress ◽  
Physical Mechanism ◽  
Fluid Pressure ◽  
Fault Slip ◽  
Rupture Velocity ◽  
Complete Spectrum ◽  
Available Energy ◽  
Different Types ◽  
Theoretical Predictions ◽  
Shallow Part

Abstract Modern geophysics highlights that the slip behaviour response of faults is variable in space and time and can result in slow or fast ruptures. However, the origin of this variation of the rupture velocity in nature as well as the physics behind it is still debated. Here, we first highlight how the different types of fault slip observed in nature appear to stem from the same physical mechanism. Second, we reproduce at the scale of the laboratory the complete spectrum of rupture velocities observed in nature. Our results show that the rupture velocity can range from a few millimetres to kilometres per second, depending on the available energy at the onset of slip, in agreement with theoretical predictions. This combined set of observations bring a new explanation of the dominance of slow rupture fronts in the shallow part of the crust or in areas suspected to present large fluid pressure.

scholarly journals A new approach to mixing techniques for enhanced performance in automated sample preparation

1995 ◽  
Vol 17 (5) ◽  
pp. 169-171
Author(s):  
François Qian ◽  
Eric Vérette ◽  
Atika El-Sayed
Keyword(s):  
Sample Preparation ◽  
Glucose Solution ◽  
New Approach ◽  
Relative Standard ◽  
Different Types ◽  
Mixing Method ◽  
Automated Sample Preparation ◽  
Standard Deviations ◽  
Mixing Techniques ◽  
Sample Dilution

In the automation of sample dilution or derivatization, the performance of the mixing technique employed when adding solvents or reagents to samples is critical. This paper presents a newly developed mixing method, based on conventional aspiration and dispensing of liquid techniques, but which considerably improves the precision of mixing. The paper discusses the results of a comparison of the technique with other methods and describes the application of the technique to several different types of sample solutions, including a highly concentrated glucose solution. The mixing technique was performed on a Gilson XL Sampling Injector, with a 1/25 dilution of a paraben solution in 2 ml vials to give relative standard deviations of 0.2 to 0.3% (N =10).

scholarly journals Validated Reversed-Phase Column High-Performance Liquid Chromatographic Method for Separation and Quantification of Polyphenolics and Furocoumarins in Herbal Drugs

2008 ◽  
Vol 91 (5) ◽  
pp. 1020-1024
Author(s):  
Raghavan Govindarajan ◽  
Dhirendra Pratap Singh ◽  
Ajay Kumar Singh Rawat
Keyword(s):  
High Performance ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Herbal Drugs ◽  
Whole Plant ◽  
Relative Standard ◽  
Different Types ◽  
Photodiode Array ◽  
Almost All ◽  
Liquid Chromatographic

Abstract A rapid column high-performance liquid chromatographic-photodiode array method has been developed for the separation and identification of secondary metabolites, especially different types of phenols and furocoumarins, in a 35 min chromatographic run. The method has been optimized and validated for selectivity, precision, recovery, and robustness with the aim of application for standardization of selected herbal drugs. Almost all of the tested compounds had linearity of >98, with relative standard deviation <10 in terms of variation of retention time. Interday and intraday variability was <5. The developed method has been successfully applied in identification and quantification of phenols and furocoumarins present in different plants, viz., Artemisia pallens (whole plant), Hibiscus rosa-sinensis DC (flower), Heracleum candicans DC (fruit), and Ficus carica Linn (bark). The results indicate that the method is rapid, accurate, and robust for the analysis of different types of phenols and furocoumarins and, hence, can be successfully used in the quality control and standardization of plant extracts and herbal drugs.

Peroxidase Mimic Activities of Copper Selenide (CuSe) Nanoplates for Sensing H2O2 and L-Cysteine

2020 ◽  
Vol 20 (9) ◽  
pp. 5369-5375
Author(s):  
Bai Maojuan ◽  
Xu Chengcheng ◽  
Huang Xuanye ◽  
Liu Yanan ◽  
Wan Jun
Keyword(s):  
Electron Microscopy ◽  
Detection Limit ◽  
Energy Dispersive Spectrometer ◽  
Catalytic Efficiency ◽  
Relative Standard Error ◽  
Colorimetric Determination ◽  
Peroxidase Mimic ◽  
Biomedical Analysis ◽  
X Ray ◽  
Relative Standard

Compared with natural enzymes, artificial mimic enzymes have been widely studied for their high stability and cost effectiveness. In this study, CuSe nanoplates as a simulated enzyme which does not contain precious metals, has peroxidase activity. CuSe nanoplates were prepared and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectrometer (EDS). Kinetic studies show that CuSe nanoplates exhibits a higher affinity for 3,3′,5,5′-teramethylbenzidine (TMB) than horseradish peroxidase (HRP). The rapid colorimetric determination of H2O2 and L-cysteine were developed based on the catalytic efficiency. The linear range of detection for H2O2 is 5.0×10−6~8.0×10−5 M, and the detection limit is 2.9×10−6 M, while the relative standard error is less than 5%. In addition, L-cysteine was detected with a detection limit of 0.2×10−6 M. The good selectivity of the determination to H2O2 and L-cysteine in aqueous solution was also achieved. CuSe nanoplates as a simulated enzyme for sensor applications would be used in environmental monitoring and biomedical analysis.

scholarly journals Improvement of NIR models for quality parameters of leech and earthworm medicines using outlier multiple diagnoses

2017 ◽  
Vol 11 (01) ◽  
pp. 1750009 ◽  
Author(s):  
Chunyan Wu ◽  
Jiashan Chen ◽  
Mengru Li ◽  
Yongjiang Wu ◽  
Xuesong Liu
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Principal Component ◽  
Solid Content ◽  
Detection Methods ◽  
Soluble Solid Content ◽  
Relative Standard Error ◽  
Diffuse Reflection Spectroscopy ◽  
Nondestructive Technique ◽  
Relative Standard

Leeches and earthworms are the main ingredients of Shuxuetong injection compositions, which are natural biomedicines. Near infrared (NIR) diffuse reflection spectroscopy has been used for quality assurance of Chinese medicines. In the present work, NIR spectroscopy was proposed as a rapid and nondestructive technique to assess the moisture content (MC), soluble solid content (SSC) and hypoxanthine content (HXC) of leeches and earthworms. This study goal was to improve NIR models for accurate quality control of leech and earthworm using outlier multiple diagnoses (OMD). OMD was composed of four outlier detection methods: spectrum outlier diagnostic (MD), leverage diagnostic (LD), principal component scores diagnostic (PCSD) and factor loading diagnostic (FLD). Conventional outlier diagnoses (MD, LD) and OMD were compared, and the best NIR models were those based on OMD. The correlation coefficients ([Formula: see text]) for leech were 0.9779, 0.9616 and 0.9406 for MC, SSC and HXC, respectively. The values of relative standard error of prediction (RSEP) for leech were 2.3%, 5.1% and 9.0% for MC, SSC and HXC, respectively. The values of [Formula: see text] for earthworm were 0.9478, 0.9991 and 0.9605 for MC, SSC and HXC, respectively. The values of RSEP for earthworm were 8.8%, 2.4% and 12% for MC, SSC and HXC, respectively. The performance of the NIR models was certainly improved by OMD.

An Integrated Model for Simulating and Evaluating Water Resources Sustainability at Laoshan Region

2014 ◽  
Vol 675-677 ◽  
pp. 880-885
Author(s):  
Jie Jun Yang ◽  
Jun Zhou
Keyword(s):  
Water Resources ◽  
Historical Data ◽  
Integrated Model ◽  
Decision Makers ◽  
Relative Standard ◽  
Different Types ◽  
Relative Errors ◽  
Water Quality And Quantity ◽  
Water Resources Utilization ◽  
Water Resources Sustainability

An integrated model was developed for evaluating water resources sustainability. In the model, a new index was developed based on nineteen indicators related socio-economic, eco-environment and water resources. The interrelationships between indicators were quantified based on mathematical models. The integrated model was applied to simulate the water resources sustainability in Laoshan Region successfully from 2010 to 2030 after validation and calibration using historical data which has low relative errors and relative standard deviation (<10%). The results indicate that the sustainable solution to water resources utilization in Laoshan Region is to supply different types of water resources to different water resources demand sectors based on requirements on water quality and quantity. The integrated model developed in this study is useful for decision-makers to simulate and evaluate the water resources sustainability.

scholarly journals Voltammetric determination of dopamine in the presence of ascorbic and uric acids using partial least squares regression: determination of dopamine in human urine and plasma

2009 ◽  
Vol 7 (3) ◽  
pp. 524-531 ◽  
Author(s):  
Morteza Bahram ◽  
Khalil Farhadi ◽  
Farzin Arjmand
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Relative Standard Error ◽  
Carbon Electrode ◽  
Least Squares Regression ◽  
Relative Standard

AbstractA new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can be oxidized at potentials close to that of DA it is difficult to determine dopamine electrochemically, although resolution can be achieved using modified electrodes. Additionally, oxidized dopamine mediates AA oxidation and the electrode surface can be easily fouled by the AA oxidation product. In this work a chemometrics strategy, partial least squares (PLS) regression, has been applied to determine dopamine in the presence of AA and UA without electrode modification. The method is based on the electrooxidation of dopamine at a glassy carbon electrode in pH 7 phosphate buffer. The dopamine calibration curve was linear over the range of 1–313 μM and the limit of detection was 0.25 μM. The relative standard error (RSE %) was 5.28%. The method has been successfully applied to the measurement of dopamine in human plasma and urine.

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