Showing papers on "Calibration curve published in 1985"

Fluorescent calibration microbeads simulating stained cells

Abstract: A method of calibrating a flow cytometer or fluorescent microscope is based on a set of highly uniform microbeads associated with a fluorescent dye in such a way that the microbeads have the same excitation and emission spectral properties as the samples which are to be measured The calibration values of the microbeads are plotted against the relative fluorescence intensity peak channel for each microbead in the set From this calibration plot, the relative fluorescence intensity peak channel of the sample is translated into equivalent soluble fluorescent dye molecules per sample particle The calibration values of the standard microbeads are determined against solutions of the dyes In cases where the background scatter of the bulk microbeads suspensions is too high for a direct determination against the solutions, a different set of microbeads with low background scatter is calibrated against the dye solutions and used to make an initial calibration of a flow cytometer or fluorescent microscope, which in turn, is used to calibrate the uniform microbead standards A novel method of making the microbead standards is also disclosed

Estimating ammonia volatilization from flooded rice fields by simplified techniques

Abstract: Two simplified methods for assessing the emission of ammonia, from fertilized, flooded rice (Oryza sativa L. cv. Inga) fields without affecting the plant's environment, are described and compared with an established micrometeorological method. Method A requires a circular plot of a 25-m radius over which wind speed and atmospheric ammonia concentrations are observed at 0.8 m above the floodwater. Method B requires measurements of ammoniacal nitrogen concentration, pH and temperature in the floodwater, and wind speed at a fixed height. Method A is the more accurate technique and requires fewer measurements. It appears that one calibration curve relating vertical flux of ammonia to these measurements can be applied in widely different environments. Method B is not only less accurate than Method A but appears to require different calibration curves to determine vertical flux for different environments. However, this method may be more useful for comparing ammonia losses from several different fertilizer treatments since only small plot areas are required for each treatment. Method B can be calibrated easily for each site by one set of simultaneous measurements on one treatment plot, using Method A.

Performance of a TSI aerodynamic particle sizer

Abstract: Calibration curves of the aerodynamic particle sizer (APS) under different sets of operating conditions (i.e., pressure drop across the nozzle, flow rate, and ambient pressure) were obtained. Materials used included oleic acid (OA), dioctyl phthalate (DOP), polystyrene latex (PSL), and fused aluminosilicate particles (FAP). The effect of particle density on the calibration was not found to be significant among test aerosols (in the density range from 0.89 to 2.3 g/cm3). Calibration curves obtained at reduced ambient pressure were different from the manufacturer's curve, indicating that recalibration of the APS is required if other than standard operating conditions are used. However, all the curves can be consolidated into a unique curve that relates the Stokes number at the nozzle exit to the normalized particle velocity (particle velocity divided by gas velocity). Methods for calculating gas velocity, particle velocity, and other pertinent parameters for the APS were developed and the results are presen...

Telemetric in-vivo calibration method and apparatus using a negative pressure applicator

Abstract: A method and apparatus are presented here which extend previous concepts of my patents and papers involving the in-vivo calibration of a telemetric pressure sensor by utilizing variations of positive and negative applied pressures on the skin which overlies the sensor. The sensor has a diaphragm means which, on one side, senses bodily pressure to be measured and, on the other side, senses the pressure under the skin. By pressing or pulling on the skin with positive and negative pressure applied to the outside of the skin, a zero point calibration of the device is achieved, and also a full calibration curve of the device, meaning its diaphragm means movement versus differential pressure across it, can be determined. A design for negative pressure application is also revealed.

Calibration curve for infrared spectrophotometry of nitrogen in silicon

Abstract: A calibration curve for infrared absorptiometry of nitrogen in silicon at 963 cm−1 was obtained by the use of charged particle activation analysis with the 14N(p, α) 11C reaction. For as‐grown floating zone (FZ) silicon, it is expressed as [nitrogen concentration at. cm−3)] =(1.83±0.24)×1017 (absorption coefficient). For heat‐treated FZ silicon and Czochralski (CZ) silicon, this relation was found to give underestimated nitrogen concentration suggesting the existence of infrared insensitive nitrogen.

New Approach to Calibrating Bed Load Samplers

Abstract: Cyclic variations in bed load discharge at a point, which are an inherent part of the process of bed load movement, complicate calibration of bed load samplers and preclude the use of average rates to define sampling efficiencies. Calibration curves, rather than efficiencies, are derived by two independent methods using data collected with prototype versions of the Helley‐Smith sampler in a large calibration facility capable of continuously measuring transport rates across a 9 ft (2.7 m) width. Results from both methods agree. Composite calibration curves, based on matching probability distribution functions of samples and measured rates from different hydraulic conditions (runs), are obtained for six different versions of the sampler. Sampled rates corrected by the calibration curves agree with measured rates for individual runs.

Experimental and theoretical calibration of a PIXE setup for K and L X-rays

Abstract: K and L line calibration has been performed for a PIXE setup by the independent use of experimental and theoretical methods. In the former case, thin film standards of known thicknesses were applied, while in the latter one cross section values were derived from different theoretical models. Programs REV5S and PIXEKL developed here were used for spectrum evaluation and concentration determination, respectively. They proved to be reliable and especially appropriate for routine serial evaluation of spectra measured on samples of nearly identical matrices. As a result of the work, an accurate calibration of the setup has been obtained and it was shown that experimental and theoretical techniques used lead to calibration curves which fit each other reasonably well.

Further Developments in the Methodology of Surface Analysis by FT-IR: Quantitative Aspects of Diffuse Reflectance Methods

Abstract: The quantitative aspects of diffuse reflectance FT-IR are explored for standard E-glass/AAPS (N-2-aminoethyl-3-aminopropyltrimethoxysilane) treated samples. Nondestructive sample preparation procedures are used. One generates calibration curves by plotting the normalized integrated intensity of the coupling agent bands in the 2990-2800 and 1700-1500 cm−1 regions vs. the concentration of the treatment solution. The data are derived by DRIFT spectroscopy, and the above results are plotted for the overlayer technique as well as for no overlayer. The scatter in the quantitative data due to fiber orientation effects has been measured and is found to be significant (20-30%). However, averaging over several orientations of the fibers results in a linear dependence of the integrated intensities of the coupling agent bands on solution concentration. The well-known breakpoint that has been observed for other coupling agent systems does not appear in the curve derived from the averaged spectra. The above-mentioned scatter is eliminated by the use of KBr overlayers on the samples. Linear calibration curves relating band intensity to concentration can be constructed. When the overlayer procedure is used, breakpoints do occur in the calibration curves. The position of these breakpoints agrees well with observations for the similar coupling agent γ-APS.

Accurate electron probe determination of aluminum composition in (Al, Ga)As and correlation with the photoluminescence peak

Abstract: The composition of Alx Ga1−xAs has been measured with improved accuracy by electron probe microanalysis using an aluminum‐copper alloy standard rather than an elemental aluminum standard. Details of the experimental procedure are given. A calibration curve, relating the photoluminescence peak energy (Ep) to aluminum concentration (x), has been obtained. A least‐squares fit to the data gives Ep(eV)=1.42+1.45x−0.25x2 for 0

Basis weight gauge standardizing method and system

Abstract: OF THE DISCLOSURE An improved technique for standardizing a basis weight gauge used to measure the weight per unit area of sheet material is described. The gauge is of the type that has a radiation source and detector defining a gap through which the sheet material is fed and across which the radiation is directed. The amount of radiation detected is a measure of the basis weight of the material. The gauge also includes a standard disc having a predetermined and stable basis weight and which can be swung into the radiation path. The method involves firstly constructing two calibration curves each showing basis weight on a first axis versus a function of transmission ratio on a second axis, the first calibration curve being constructed without simulated dirt and the second calibration curve being constructed with simulated dirt. The next step is the construction of a standardization curve by plotting the displacement of one calibration curve relative to the other measured parallel to the first axis. The gauge is standardized during operation by placing the standard disc in the gap without the sheet material in the gap and determining the standardize transmission ratio,determining a correction factor based upon the standardize transmission ratio and applying the correction factor to the uncorrected basis weight to determine a corrected basis weight.

Field calibration of a recording turbidity meter

Abstract: The methods in common use for collecting data on suspended solids concentrations in streamflow and for calculating total load are either inaccurate or unnecessarily expensive. Recording turbidity meters offer a potential solution to these problems when used in association with a calibration between suspended solids concentrations and turbidity. In this paper a method is described for the field calibration of a recording turbidity meter. Optical neutral density filters are used instead of Formazin standards to check instrumental consistency in the field. Calibration with suspended solids concentrations is carried out using an automatic sampler whose operation is recorded together with turbidity on a two track recorder. The calibration curve is a second order polynomial in which turbidity explains 97% of the variance in suspended solids concentration.

Determination of strongly curved calibration graphs in flame atomic-absorption spectrometry: comparison of manually drawn and computer-calculated graphs

Abstract: The non-linear portion of the calibration graphs in flame atomic-absorption spectrometry (AAS) offers more precise analytical results provided that the calibration graph can be determined reliably. Experimental data for three elements (Cu, Ni, Pb) and synthetic data were submitted to nine analysts and to three mathematical expressions (polynomial, cubic spline and rational function). The quality of hand-drawn and computer-calculated graphs was judged for goodness of fit and the accuracy of determining unknowns. It is concluded that results within 1% can be obtained in either instance, provided that 5–8 selected reference solutions are used and weighting factors are applied in the least-squares fit. With a simple criterion to guide the selection of the correct degree, the ordinary polynomial is the preferred expression to fit flame AAS data. With these recommendations it is possible to extend the calibration graph at least to the point where the slope is reduced to 25% of its value at the origin.

Analytical Characteristics of the Microwave-Induced Nitrogen Discharge at Atmospheric Pressure (MINDAP)

Abstract: A microwave-induced plasma (MIP) is sustained at atmospheric pressure with the use of nitrogen as the plasma and nebulizer gas. The plasma is operated at 2450 MHz and has been optimized at 250 W of rf power with a total nitrogen flow rate of 1.78 L/min. The analytical performance of this plasma has been evaluated and compared with other atmospheric pressure plasma systems. Detection limits were typically in the part-per-billion concentration range, and calibration curves were linear over three-to-five orders of magnitude. Interelement interferences were observed but were overcome with the use of releasing agents. Precision for an analytical measurement was generally better than 2% relative standard deviation.

Determination of peroxide value by conventional difference and difference-derivative spectrophotometry

Abstract: The spectrophotometric behavior of the system iodide-iodine-iodate-oxygen was studied, and a simple iodometric method to determine peroxide value by conventional, difference or difference-derivative spectrophotometry was developed. The procedures are carried out inside standard photometric cells containing iodide solution to which the sample is added. Absorbance or its first derivative with respect to wavelength is measured to determine iodine concentration by means of calibration curves. No special care to avoid iodide oxidation by atmospheric oxygen is necessary.

Preparation of calibration curve

Abstract: PURPOSE:To reduce time and labor in the preparation of a calibration curve by automatically performing the detection of abnormal data and the recalculation of the calibration curve employing an allowable level in addition to the calibration curve calculating operation to permit the operator to accomplish all simply by initially inputting data of a reference sample. CONSTITUTION:When the operator inputs a measurement starting command into an computation control circuit 2 from a keyboard 3, the circuit 2 stores the results of the measurement of an analyzer 1 into a memory 4. In the preparation of a calibration curve, the operator inputs a known concentration of a reference sample to make the computation control circuit 2 execute a measuring operation and the results of the measurement are stored into the memory 4 while being outputted to a display 5 to plot a graph. The operator determines wether the calibration curve is linear, curve of second or third order observing the graph and inputs the order of the line judged from the keyboard 3 to provide a calibration curve preparation command to the computation control circuit 2. Thus, a calibration curve is determined according to a flow chart defined.

Measurement of the Specific Surface Area of Clays by Internal Reflectance Spectroscopy

Abstract: The specific surface area, S, of a clay is commonly measured by the adsorption of ethylene glycol monoethyl ether (EGME); however, this method can be tedious and time consuming, especially if the clay is saturated with a monovalent, highly hydrated cation. An alternative method for measuring S was developed involving infrared internal reflectance spectroscopy. This method is based on the discovery that the ratio of R1, the reflectance of a clay-HOD mixture at the frequency of O-D stretching, to R2, the reflectance of the mixture at the frequency of H-O-D bending, is linearly related to S. The correlation coefficient between R~/R2 and S, as measured by the adsorption of EGME, was 0.995. Consequently, a calibration curve of R1/R2 versus S was constructed, and the measured values of R~/R2 for any clay-HOD mixture were referred to it for the determination of S. Results were obtained in triplicate in about an hour; hence, this method of determining S is more rapid and convenient than that involving the adsorption of EGME. Moreover, it applies to clays in a natural condition, i.e., swollen in water.

In Situ Determination of the Slope of the Calibration Curve of a Neutron Probe Using a Volumetric Technique

Abstract: This paper presents a volumetric technique that provides an in situ estimate of the slope of the calibration curve of a neutron probe. The calculated slopes agreed well with slopes that were obtained by field calibration using gravimetric techniques or by calibration using soil packed in barrels. The latter technique showed the importance of packing the soil to field density, as density strongly affected the intercept of the calibration curve due to the content of moderators, including constitutional hydrogen in the red-yellow podzolic soil. The major advantage of the proposed technique is the direct determination of the slope of the calibration curve and, consequently, the ability to permit accurate estimates of changes in water content.

Method for gel permeation chromatography calibration and the evaluation of Mark–Houwink constants

Abstract: A novel and simple method is described for evaluation of the Mark–Houwink constants and developing of GPC calibration curve for a polymer where only broad molecular weight distribution samples are available. The method demands the GPC calibration curve for polystyrene and measurement of the intrinsic viscosity and GPC chromatogram of several samples. Results of applying the procedure to polystyrene and poly(methyl methacrylate) are presented.

Determination of Diclofenac Sodium in Synovial Fluid by High Performance Liquid Chromatography

Abstract: Due to the limited supply of blank synovial fluid, the usual practice of preparing a calibration curve for the biological sample of measurement is not practical for synovial fluid drug level determination. The linearity and correlation of peak height ratio between plasma and synovial fluid samples were investigated in this study. Excellent linear relationship is obtained from the calibration curves for both biological samples. In addition, excellent correlation of peak height ratios between plasma and synovial fluid indicates that the plasma calibration curve can be used in lieu of a synovial fluid calibration curve (slope 0.9154; intercept not statistically different than zero; and r-0.999 with N=13). According to this linear relationship, synovial fluid levels can be calculated based on the concentration as determined from the plasma calibration curve and divided by 0.9154. The extraction efficiences were comparable when diclofenac was spiked into human plasma or synovial fluid samples but the ...

Temperature of incandescent lamps

Abstract: A method for determining filament temperatures of commercially available incandescent lamps has been presented. The light emitted by a filament at two well‐defined wavelengths has been measured by means of two silicon solar cells with interference filters. Since the ratio r of the two signals so determined is a function of the filament temperature, an r against T calibration curve is needed, in order to obtain the filament temperature itself. This calibration curve is determined by means of the well‐known dependence of tungsten resistivity on absolute temperature. Considerations about the color index of a star can be raised.

Ion analyzer calibration cell

Abstract: of the Disclosure Apparatus for calibrating an ion analyzer comprises a calibration cell having defined therein a first volume for measuring an ion concentration of a sample when the instrument is operated in a monitoring and a second volume for measuring the ion concentration when the instrument is operated in a calibration mode. The first volume is included in, and forms part of, the second volume so that the matrix for the calibration measurement is essentially identical to that for the sample measurement, A double known-addition is used during the calibration mode to determine the calibration parameters.

A calibration curve for room‐temperature resistivity versus donor atom concentration in Si:As

Abstract: Neutron activation measurements of arsenic concentration have been made on a set of samples cut from melt‐grown crystals of Si:As in the concentration range from 7.8×101 8 cm− 3 to 1.1×101 9 cm− 3. Measurements of electrical resistivity at room temperature on the same samples provide information for a calibration curve of resistivity ρ versus the donor concentration n D . The data are combined with earlier measurements of ρ and n D made by Backenstoss using radioactive tracer techniques at lower As concentration to yield a calibration curve covering the donor concentration range from 1.0×101 8 cm− 3 to 1.1×101 9 cm− 3. A fourth‐order polynomial expression for the function ρ vs n D is compared with data derived from Hall constant determinations of donor concentration. Using the expression relating the Hall constant to the electron density, R H =A(n D )/n e, we are able to obtain values of the function A(n D ) for arsenic concentrations in the range 3.0×101 8 cm− 3 to 8.6×101 8 cm− 3. These values for Si:As are compared to the A(n D ) values for Si:P.