scholarly journals Determination of Birefringence of Uniaxial Crystals: The Use of Conoscopy for Quantitative Measurements

1996 ◽  
Vol 4 (5) ◽  
pp. 12-13
Author(s):  
Mohan Srinivasarao
Keyword(s):  
Refractive Index ◽  
Liquid Crystals ◽  
Optical Microscope ◽  
Visual Observation ◽  
Quantitative Measurements ◽  
The One

Often times one is asked the question "how can the optical microscope be used to make quantitative measurements?" The microscope certainly lets one observe the sample {whatever the sample may be) and make qualitative statements about what is it one is looking at. It has been used for various purposes from just visual observation in brightfield, reflection and the one that is near and dear to my heart, observations under crossed polarizers. This certainly allows one to identify materials as being isotropic or anisotropic. If one works on materials like liquid crystals, an optical microscope is a tool that is used all the time. It certainly allows for identification of various phases of liquid crystals based on the defects and textures that can be observed. All of this is somewhat qualitative in nature. By that I mean that the observations do not lend themselves to obtain, say for example, refractive index or birefringence of the material. I would like to describe a technique that will allow one to do just that.

Laser Deflection Measurements for the Determination of Temperature and Charge Carrier Distributions in 4H-SiC Power Diodes

2009 ◽  
Vol 615-617 ◽  
pp. 267-270 ◽  
Author(s):  
Dorothea Werber ◽  
Gerhard Wachutka
Keyword(s):  
Refractive Index ◽  
Charge Carrier ◽  
Current Flow ◽  
Spatial Modulation ◽  
Carrier Injection ◽  
The Real ◽  
Power Diodes ◽  
The One ◽  
Real Refractive Index

A change of the electron and hole densities n and p and of the lattice temperature T modulates the real optical refractive index nopt of the device under test. In the forward conducting state the electron and hole distributions n(x) and p(x) in the i-region of the device are generated by the action of carrier injection from the n- and p-emitters. The device is locally heated by Joule and recombination heat, leading to a temperature distribution T(x). The gradients of temperature and charge carrier densities cause a spatial modulation of the real refractive index nopt(x). A laser beam transmitted orthogonally to the direction of current flow of the device is deflected by the gradient of nopt(x). Concurrent deflections caused simultaneously by the carrier gradients on the one side and by the temperature gradient on the other side can be discriminated by their different time constants.

Determination of Copolymer Composition by Combustion Analysis for Carbon and Hydrogen

1960 ◽  
Vol 33 (4) ◽  
pp. 1132-1141
Author(s):  
Lawrence A. Wood ◽  
Irving Madorsky ◽  
Rolf A. Paulson
Keyword(s):  
Refractive Index ◽  
Present Method ◽  
Copolymer Composition ◽  
Combustion Analysis ◽  
Physical Methods ◽  
Accuracy And Precision ◽  
Styrene Content ◽  
The One ◽  
Relative Measurements

Abstract The procedure described attains its accuracy and precision by the refinement and improvement of conventional simple operations over a periods of years. The trend in analysis recently is, of course, toward the use of rapid physical methods. In a great many instances these involve relative measurements requiring the initial establishment of reference materials with compositions determined by methods such as the one here described, which bases the numbers derived solely on readings of an analytical balance. In fact, as already mentioned, one of the principal applications of the present method has been in the establishment of the relation between refractive index and styrene content for SBR polymers so that refractive index measurements can be used in routine determinations of bound styrene content.

Determination of Polymer Composition of Rubber Vulcanizates

1971 ◽  
Vol 44 (5) ◽  
pp. 1278-1281
Author(s):  
D. W. Carlson ◽  
H. C. Ransaw ◽  
A. G. Altenau
Keyword(s):  
Carbon Black ◽  
Polymer Composition ◽  
Infrared Analysis ◽  
Pyrolysis Products ◽  
Nmr Spectrum ◽  
Quantitative Measurements ◽  
Infrared Studies ◽  
The One ◽  
The Relationship

Abstract Various methods exist for the quantitative determination of the polymer composition in vulcanized stocks. These methods consist of dissolving the vulcanizates in boiling o-dichlorobenzene, removal of the carbon black by filtration, and then infrared determination of the polymer. Pyrolysis of the stock followed by infrared analysis of the products has also been used. This technique had the disadvantages of requiring an analysis of products other than the original polymer or polymers. The infrared calibration based on polymers would no longer be valid. There may also be some uncertainty about changes in the relationship between the original microstructure and the pyrolysis products. Other infrared studies have been made but no quantitative measurements were reported. Recently an NMR method was published for vulcanizate analysis. The method consisted of dissolving the vulcanizate in hexachlorobutadiene, recording the NMR spectrum of the solution, and determining the total amount of butadiene, styrene, and natural rubber from the spectrum. Good results were obtained on a variety of vulcanizates. The one disadvantage of the method was that only a limited amount of microstructure data could be obtained. This was due to the lack of resolution of the 60-megacycle NMR. We have now developed a technique which allows enough of the rubber to dissolve in carbon disulfide for infrared analysis. This solution is free of carbon black. Infrared analysis provides microstructure data on the butadiene and/or isoprene portions as well as the total styrene content.

scholarly journals Holistic Approach to R&D Products’ Evaluation for Commercialization under Open Innovations

2022 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Nataliya Chukhray ◽  
Oleksandra Mrykhina ◽  
Ivan Izonin
Keyword(s):  
Refractive Index ◽  
Marketing Research ◽  
Holistic Approach ◽  
Added Value ◽  
Optical Range ◽  
Crystalline Materials ◽  
Market Effects ◽  
The One

A holistic approach to R&D products’ evaluation for commercialization under open innovations is developed. The approach is tested on the example of the device of the interferometric determination of the refractive index of crystalline materials in the optical range. The proposed approach will allow setting a price that will satisfy all the parties of a transfer agreement with a higher level of accuracy and will meet market requirements. Unlike popular methods of evaluating the R&D product, a holistic approach will, on the one hand, be based on the actual costs and the break-even level of a R&D product and, on the other hand, will determine how much the consumer is receptive to a R&D product, and, then again, will show how the added value of the product will develop under the influence of market effects. It is noted that the application of a holistic approach to R&D products’ evaluation for commercialization should be supplemented by assessing the willingness of potential customers to purchase this R&D product at a specific price. It is proved that the proposed holistic approach to R&D products’ evaluation for commercialization is multifunctional. The approach can be applied to different types of economic activity, R&D products, and types of markets. The obtained prices based on the application of a holistic approach to R&D products’ evaluation for commercialization and the results of marketing research of the interferometry market testified to potential prospects of the commercialization of a R&D product of the interferometric determination of the refractive index of crystalline materials in the optical range and its long-term competitiveness. Based on the results, the key provisions of the concept of providing competitive benefits for the period of implementation of the analyzed R&D product are identified. Taking into account fundamental elements of the open innovation paradigm underpins the authors’ holistic approach.

The Control of Errors in Infrared Spectrophotometry. VI. The Evaluation of Optical Constants by Combined Transmission and Attenuated Total Reflection Measurements

1980 ◽  
Vol 34 (6) ◽  
pp. 652-656 ◽  
Author(s):  
T. G. Goplen ◽  
D. G. Cameron ◽  
R. N. Jones
Keyword(s):  
Refractive Index ◽  
Optical Constants ◽  
Statistical Treatment ◽  
Statistical Error ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Integration Constant ◽  
The One ◽  
Improved Technique

An improved technique is described for the determination of the optical constants of liquids in the infrared. It is based on a combination of transmission and attenuated total reflection (ATR) measurements. A novel application of the Kramers-Kronig transform function is involved whereby a single-valued integration constant is derived from a vector of refractive index measurements obtained by ATR. These are measured over a wavenumber range where the absorbance is low. It has been shown in earlier work that by an appropriate choice of a low refractive index contact material (in our case sodium chloride) the ATR method has high precision and accuracy under these conditions. The accuracy of the method is evaluated on the basis of a statistical treatment of the propagation of the estimated errors in the experimentally measured quantities, viz., the transmittance, the cell thickness, and the ATR measurements which establish the integration constant (anchor point) of the Kramers-Kronig transform function. The transmittance measurements are made at several cell thicknesses. The data reduction computer program, by which the optical constants are evaluated from the transmission measurements, monitors these sets of data and selects at each wavenumber the one having the minimal statistical error.

scholarly journals Properties of magnesium oxide boards used as sheathing in exterior walls

2019 ◽  
Vol 282 ◽  
pp. 02091
Author(s):  
Stefanie Wøhler Nielsen ◽  
Carsten Rode ◽  
Tommy Bunch-Nielsen ◽  
Kurt Kielsgaard Hansen ◽  
Wolfgang Kunther ◽  
...  
Keyword(s):  
Magnesium Oxide ◽  
Salt Water ◽  
Ambient Air ◽  
Dry Mass ◽  
Optical Microscope ◽  
Visual Observation ◽  
Moisture Uptake ◽  
Vapour Permeability ◽  
Scanning Electron

Sheathing boards based on magnesium oxide (MgO) became very popular in the Danish market around the year 2010. However, it was realized a few years later that they condensed humidity from ambient air. The leakage from the boards led to severe problems with corrosion of metallic components and moisture uptake and degradation of wooden members. The boards have been banned from use in the Danish market since 2015, while damage cases valuing around 370 million EUR still need to be reconciled [1]. The binder in MgO board is formed by a chemical reaction between MgO and MgCl2. However, MgSO4 is a possible alternative to MgCl2, and such boards may have smaller moisture uptake, to reduce this issue. This paper gives an account of recent activities to compare properties of MgO boards, based on chlorides or sulphates. The investigations comprise: (1) Analysis of elemental composition and crystalline components, (2) Examination in optical microscope and scanning electron microscope, (3) Determination of moisture retention and water vapour permeability, (4) Analysis of chemical composition of leaked salt water from boards, and (5) Visual observation of decomposition and determination of dry mass change after exposure to high humidity.

Two-Stage Procedure for the Quantitative Determination of Autoprothrombin III Concentration and Some Applications

1967 ◽  
Vol 18 (01/02) ◽  
pp. 198-210 ◽  
Author(s):  
Ronald S Reno ◽  
Walter H Seegers
Keyword(s):  
Prothrombin Time ◽  
Factor Vii ◽  
Two Stage ◽  
Pronounced Increase ◽  
One Stage ◽  
Assay Procedure ◽  
Bovine Plasma ◽  
The One ◽  
Autoprothrombin C

SummaryA two-stage assay procedure was developed for the determination of the autoprothrombin C titre which can be developed from prothrombin or autoprothrombin III containing solutions. The proenzyme is activated by Russell’s viper venom and the autoprothrombin C activity that appears is measured by its ability to shorten the partial thromboplastin time of bovine plasma.Using the assay, the autoprothrombin C titre was determined in the plasma of several species, as well as the percentage of it remaining in the serum from blood clotted in glass test tubes. Much autoprothrombin III remains in human serum. With sufficient thromboplastin it was completely utilized. Plasma from selected patients with coagulation disorders was assayed and only Stuart plasma was abnormal. In so-called factor VII, IX, and P.T.A. deficiency the autoprothrombin C titre and thrombin titre that could be developed was normal. In one case (prethrombin irregularity) practically no thrombin titre developed but the amount of autoprothrombin C which generated was in the normal range.Dogs were treated with Dicumarol and the autoprothrombin C titre that could be developed from their plasmas decreased until only traces could be detected. This coincided with a lowering of the thrombin titre that could be developed and a prolongation of the one-stage prothrombin time. While the Dicumarol was acting, the dogs were given an infusion of purified bovine prothrombin and the levels of autoprothrombin C, thrombin and one-stage prothrombin time were followed for several hours. The tests became normal immediately after the infusion and then went back to preinfusion levels over a period of 24 hrs.In other dogs the effect of Dicumarol was reversed by giving vitamin K1 intravenously. The effect of the vitamin was noticed as early as 20 min after administration.In response to vitamin K the most pronounced increase was with that portion of the prothrombin molecule which yields thrombin. The proportion of that protein with respect to the precursor of autoprothrombin C increased during the first hour and then started to go down and after 3 hrs was equal to the proportion normally found in plasma.

SIMPLIFIED DEXAMETHASONE SUPPRESSION TEST

1969 ◽  
Vol 61 (2) ◽  
pp. 219-231 ◽  
Author(s):  
V. H. Asfeldt
Keyword(s):  
Cushing’S Syndrome ◽  
Normal Subjects ◽  
Cushing's Syndrome ◽  
Dexamethasone Suppression Test ◽  
Clinical Value ◽  
Suppression Test ◽  
The One ◽  
Steroid Excretion ◽  
Dexamethasone Suppression

ABSTRACT This is an investigation of the practical clinical value of the one mg dexamethasone suppression test of Nugent et al. (1963). The results, evaluated from the decrease in fluorimetrically determined plasma corticosteroids in normal subjects, as well as in cases of exogenous obesity, hirsutism and in Cushing's syndrome, confirm the findings reported in previous studies. Plasma corticosteroid reduction after one mg of dexamethasone in cases of stable diabetes was not significantly different from that observed in control subjects, but in one third of the insulin-treated diabetics only a partial response was observed, indicating a slight hypercorticism in these patients. An insufficient decrease in plasma corticosteroids was observed in certain other conditions (anorexia nervosa, pituitary adenoma, patients receiving contraceptive or anticonvulsive treatment) with no hypercorticism. The physiological significance of these findings is discussed. It is concluded that the test, together with a determination of the basal urinary 17-ketogenic steroid excretion, is suitable as the first diagnostic test in patients in whom Cushing's syndrome is suspected. In cases of insufficient suppression of plasma corticosteroids, further studies, including the suppression test of Liddle (1960), must be carried out.

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