scholarly journals Areal Density Measurement is a Convenient Method for the Determination of Porcine Islet Equivalents without Counting and Sizing Individual Islets

2003 ◽  
Vol 12 (1) ◽  
pp. 33-41 ◽  
Author(s):  
N. Lembert ◽  
J. Wesche ◽  
P. Petersen ◽  
M. Doser ◽  
H. D. Becker ◽  
...  
Keyword(s):  
Gradient Centrifugation ◽  
Density Measurement ◽  
Areal Density ◽  
Single Step ◽  
Method Error ◽  
Entire Area ◽  
Density Measurements ◽  
Islet Mass ◽  
Porcine Islet

The determination of islet mass is important for the normalization of islet experiments in the laboratory and for the precise dosing of islets for transplantation. The common microscopical analysis is based on individual islet sizing, calculation of the frequency distribution, and conversion into islet equivalents (IEQ), which is the volume of a spherical islet with a diameter of 150 μm. However, islets are of irregular form, which makes this determination user dependent, and the analysis is irreproducible once the original sample is discarded. This routine technique of islet quantification was compared with the analysis of areal density measurements. It was assumed that the entire area occupied by islets can be expressed in IEQ without sizing and counting individual islets. Porcine islets were isolated by continuous digestion/filtration and purified by gradient centrifugation. Purified islets were stained with dithizone and were repeatedly pictured under the microscope with random area selection. A total of 51 pictures was taken from 11 different purifications and stained islets were detected by digital image analysis. The correlation coefficient (r) between both analyses was 0.977 with an underestimation of islet yield by areal density detection (slope: 0.75 ± 0.03). Areal density analysis per picture took about 1 min, which is about 10 times faster than the traditional method without increasing the method error (CV 2.1% vs. 2.7%). In summary, areal density measurements allow a rapid and reproducible estimation of IEQ without counting individual islets. It can be performed in a single step analysis without computer programming and is valuable for online determinations of islet yield preceding transplantation.

scholarly journals The density–salinity relation of standard seawater

2017 ◽  
Author(s):  
Hannes Schmidt ◽  
Steffen Seitz ◽  
Egon Hassel ◽  
Henning Wolf
Keyword(s):  
North Atlantic Ocean ◽  
Density Measurement ◽  
Chemical Compositions ◽  
Constant Composition ◽  
Target Uncertainty ◽  
Density Measurements ◽  
The North ◽  
Density Values ◽  
Reference Equation

Abstract. The determination of salinity by means of electrical conductivity relies on a constant salt composition in the North Atlantic Ocean, as standard seawater, which is required for salinometer calibration, is produced therefrom. In order to verify the long-term constant composition of standard seawater, it was proposed to perform density measurements on standard seawater, as the seawater density is sensitive to all salt components. Thus, density measurements can detect any change in the composition of seawater. A conversion of the density values to salinity can be performed by means of a density–salinity relation. To use such a relation with a target uncertainty in salinity comparable to that in salinity obtained from conductivity measurements, a density measurement at an uncertainty level of 2 ppm is mandatory. In this article, a new density–salinity relation is presented based on such accurate density measurements. The underlying substitution measurement method is described, density corrections for uniform isotopic and chemical compositions are reported, and the density–salinity relation is presented. The comparison of densities calculated using the new relation with those calculated using the present reference equation of state TEOS-10 suggests that the density accuracy of TEOS-10 and that of some of its underlying density measurements are overestimated. The new density–salinity relation may be used to verify the constant composition of standard seawater by means of routine density measurements.

DETERMINATION OF THE FUNCTION OF THE ROD’S CROSS-SECTIONAL AREA USING VIBRATION EIGENFREQUENCIES

2020 ◽  
Vol 0 (4) ◽  
pp. 19-24
Author(s):  
I.M. UTYASHEV ◽  
◽  
A.A. AITBAEVA ◽  
A.A. YULMUKHAMETOV ◽  
◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Variable Cross ◽  
Sectional Area ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Method Error ◽  
Various Boundary Conditions ◽  
Elastic Fixation ◽  
Crosssectional Area

The paper presents solutions to the direct and inverse problems on longitudinal vibrations of a rod with a variable cross-sectional area. The law of variation of the cross-sectional area is modeled as an exponential function of a polynomial of degree n . The method for reconstructing this function is based on representing the fundamental system of solutions of the direct problem in the form of a Maclaurin series in the variables x and λ. Examples of solutions for various section functions and various boundary conditions are given. It is shown that to recover n unknown coefficients of a polynomial, n eigenvalues are required, and the solution is dual. An unambiguous solution was obtained only for the case of elastic fixation at one of the rod’s ends. The numerical estimation of the method error was made using input data noise. It is shown that the error in finding the variable crosssectional area is less than 1% with the error in the eigenvalues of longitudinal vibrations not exceeding 0.0001.

scholarly journals Bone Mineral Density Measurements: Are they Worth While?

1996 ◽  
Vol 89 (8) ◽  
pp. 457-461 ◽  
Author(s):  
D J Torgerson ◽  
C Donaldson ◽  
D M Reid
Keyword(s):  
Bone Mineral Density ◽  
Bone Density ◽  
Bone Mineral ◽  
Diagnostic Tool ◽  
Screening Tool ◽  
Density Measurement ◽  
Bone Density Measurement ◽  
Mineral Density ◽  
Density Measurements ◽  
Bone Mineral Measurements

Bone mineral density measurements have been criticized on the grounds that they are not a worth-while screening tool. In this paper we argue that bone mineral measurements can be an efficient diagnostic tool even if they are not of proven value for screening. There is complex relationship between the costs of a measurement, the intervention and the predictive value of the test all of which must be accounted for when assessing the value of a bone density measurement. For bone density measurements to be used for screening, a wider evaluation needs to be undertaken compared with that for their use as a diagnostic tool. We address some common objections, for example, that low compliance with screening would undermine efficiency, and show that these are not relevant. Evaluations of screening need to address issues that are likely to affect efficiency.

scholarly journals A single-step purification method for the precise determination of the antimony isotopic composition of environmental, geological and biological samples by HG-MC-ICP-MS

2021 ◽  
Author(s):  
Ferrari Colin ◽  
Resongles Eléonore ◽  
Freydier Rémi ◽  
Casiot Corinne
Keyword(s):  
Isotopic Composition ◽  
Biological Samples ◽  
Precise Determination ◽  
Single Step ◽  
Functionalized Silica ◽  
Purification Method ◽  
Silica Powder ◽  
Icp Ms ◽  
Single Step Purification

Thiol-functionalized silica powder allowed single-step purification of antimony for exploring stable Sb isotope signatures in the environment.

scholarly journals Radiographic areal density measurements on the OMEGA EP laser system

2021 ◽  
Vol 92 (5) ◽  
pp. 053901
Author(s):  
Camelia V. Stan ◽  
Alison M. Saunders ◽  
Matthew P. Hill ◽  
Tom Lockard ◽  
Kyle Mackay ◽  
...  
Keyword(s):  
Laser System ◽  
Areal Density ◽  
Density Measurements

Single step method for the accurate concentration determination of polysorbate 80

1997 ◽  
Vol 786 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Travis H. Tani ◽  
Jamie M. Moore ◽  
Thomas W. Patapoff
Keyword(s):  
Single Step ◽  
Polysorbate 80 ◽  
Step Method ◽  
Concentration Determination

scholarly journals Simultaneous determination of iron and copper in children's sera by FAAS

2011 ◽  
Vol 61 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Svjetlana Luterotti ◽  
Tončica Kordić ◽  
Slavica Dodig
Keyword(s):  
Atomic Absorption ◽  
Simultaneous Determination ◽  
Sample Pretreatment ◽  
Single Step ◽  
Design Experiment ◽  
New Approach ◽  
Flame Atomic Absorption ◽  
Reference Methods ◽  
Atomic Absorption Spectrometric

Simultaneous determination of iron and copper in children's sera by FAASA new and simple flame atomic-absorption spectrometric (FAAS) method is proposed for simultaneous determination of iron and copper in children's sera. It is based on single-step sample pretreatment (deproteinization with 3 mol L-1HCl, ratio 1:1) and single-step calibration using 1.5 mol L-1HCl standard. During method's optimization a short multifactorial design experiment was used. The proposed method assures accuracy, sensitivity and precision comparable to that of the reference methods. The new approach is simple and time-, labour- and serum-saving, the latter being especially important in pediatric diagnostics.

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