Optical Stress Analysis of Flexural Waves in a Bar

1970 ◽  
Vol 37 (2) ◽  
pp. 331-338 ◽  
Author(s):  
J. A. Clark ◽  
A. J. Durelli
Keyword(s):  
High Speed ◽  
Sine Wave ◽  
Good Precision ◽  
Stress Distributions ◽  
Flexural Waves ◽  
Principal Stresses ◽  
Full Field ◽  
Modified Method ◽  
Photoelastic Data

A complete, direct, full-field optical determination of dynamic stress distributions by a combination of photoelastic and interferometric measurements is illustrated. The method is applied to the study of flexural waves propagating in a photoelastic, urethane rubber bar. A displacement type of transverse, dynamic loading (which has approximately the form of a decaying sine wave) is applied at one end of the bar. The loading pulse can be repeated with good precision. Individual isochromatics and isoclinics are obtained, using a still camera with a short duration (0.5 micro sec) flash. A series of isochromatics have also been obtained with a Fastax high-speed motion picture camera. Photoelastic data are supplemented by isopachic patterns obtained by a modified method of holographic interferometry recently developed by the authors. As an example of complete determination of stress distributions, a vectorial representation of the principal stresses at one instant is given. Comparisons are made with approximate theories.

Experimental analysis of high-frequency stress waves in a ring

1969 ◽  
Vol 4 (4) ◽  
pp. 297-305 ◽  
Author(s):  
A J Durelli ◽  
J A Clark ◽  
A Kochev
Keyword(s):  
High Frequency ◽  
Stress Waves ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Tangential Stresses ◽  
Photoelastic Analysis ◽  
Photoelastic Data ◽  
Axis Of Symmetry ◽  
Capacitance Gauge

This paper deals with the photoelastic analysis of stress waves in a thick ring subjected to transient high-frequency loading. The device used to apply the loading is a piezo-electric transducer which initially produces four cycles of a 31·25 kHz toneburst. The loading pulse can be reproduced with high precision. The ring is illuminated with a flash of approximately 0·5 μs duration which can be delayed in a continuously adjustable manner. Isochromatics and isoclinics can be directly observed as static patterns. Photoelastic data are supplemented by measurements obtained with a capacitance gauge used as a dynamic lateral extensometer. Satisfactory agreement is found between tangential stresses near the free boundary of the ring determined from photoelastic data and those determined from capacitance-gauge measurements. As examples of complete determination of stress distributions, the separated principal stresses are obtained along an axis of symmetry and a vectorial representation of the principal stresses is given. A wave interpretation of the data is developed and comparisons are made with available solutions of related problems.

A Rapid Method for the Determination of Principal Stresses Across Sections of Symmetry From Photoelastic Data

1938 ◽  
Vol 5 (1) ◽  
pp. A24-A28
Author(s):  
M. M. Frocht
Keyword(s):  
Free Boundary ◽  
Rapid Method ◽  
Circular Hole ◽  
Characteristic Curve ◽  
Principal Stresses ◽  
Recent Improvement ◽  
Tangential Stresses ◽  
Circular Holes ◽  
Photoelastic Data

Abstract The author discusses: (a) Mesnager’s theorem of isoclinics, (b) the characteristic curve of tangential stresses across a section of symmetry, (c) a formula for the maximum tangential stresses for the case of a central circular hole between fields of pure tension, (d) the slope of the p curve at a point corresponding to a cupic point, (e) recent improvement in the determination of free boundary stresses, and (f) formulas for the position of cupic points for two cases. A new method for the determination of the principal stresses across sections of symmetry from photoelastic data is illustrated with three examples: (1) Bars in tension or compression with central circular holes, (2) grooved beams in bending, and (3) rings or disks with circular central holes subjected to two concentrated diametral loads.

Combined enzymic-Jaffé method for determination of creatinine in serum.

1981 ◽  
Vol 27 (1) ◽  
pp. 18-21 ◽  
Author(s):  
P Masson ◽  
P Ohlsson ◽  
I Björkhem
Keyword(s):  
Reference Method ◽  
Enzyme Reaction ◽  
Creatine Phosphate ◽  
Mass Fragmentography ◽  
Good Precision ◽  
Serum Samples ◽  
Modified Method ◽  
Combined Use ◽  
High Concentrations

Abstract Concentrations of creatinine, as determined in serum by a method involving the combined use of creatinine amidohydrolase (EC 3.5.2.10) and alkaline sodium picrate were found to be factitiously low, owing to a reversal of the enzyme reaction. This effect could be eliminated by converting creatine, the product of the enzymic reaction, to creatine phosphate. The combined enzymic-Jaffé method was therefore modified to include creatine amidohydrolase, creatine kinase, ATP, and Mg2+ in the reaction mixture. The modified method has good precision. We saw no significant interferences by relatively high concentrations of acetone, acetylacetone, ADP, creatine, creatine phosphate, glucose, glycocyamine, or pyruvate. Likewise, no interferences were evident with icteric, lipemic, or hemolytic serum samples. There was an excellent agreement between creatinine values obtained with our method and by a reference method based on isotope dilution-mass fragmentography. Our method is considerably simpler than the fully enzymic method for determination of creatinine and might be a method of choice if a high accuracy is desired.

The determination of principal stresses from photoelastic data

Strain ◽  
1992 ◽  
Vol 28 (4) ◽  
pp. 153-158 ◽  
Author(s):  
S. J. Haake ◽  
E. A. Patterson
Keyword(s):  
Principal Stresses ◽  
Photoelastic Data

MODIFIED METHOD OF PREPARING CONCENTRATED SMEARS OF BONE MARROW

PEDIATRICS ◽  
1958 ◽  
Vol 21 (1) ◽  
pp. 112-113
Author(s):  
J. J. McGovern ◽  
M. Duane ◽  
R. Hebert
Keyword(s):  
Bone Marrow ◽  
Peripheral Blood ◽  
High Speed ◽  
Standard Technique ◽  
Buffy Coat ◽  
Glass Slide ◽  
Modified Method ◽  
Usual Manner ◽  
Capillary Attraction

THE FOLLOWING brief communication concerns a method of obtaining bone marrow smears which are practically devoid of dilution with cells from the peripheral blood. In the authors' experience bone marrow particles are not usually obtained from small infants and children. Therefore it has not been possible to make use of the standard technique of aspiration of the bone marrow into a heparinized syringe, placing the aspirate on a watchglass, and then selecting a particle of bone marrow for smear or imprint. Neither has the alternative method of centrifuging heparinized marrow in Wintrobe hematocrit tubes proved satisfactory, because the small quantity of marrow generally taken from infants is insufficient to fill a Wintrobe tube. Another difficulty is in separating the buffy coat from the erythrocyte layer in the Wintrobe tube. [SEE FIG. 1 IN SOURCE PDF] METHOD The present method consists of expelling two or three small drops of bone marrow from the aspirating syringe on to a glass slide; this is transferred by means of capillary attraction into a micro-hematocrit tube. The micro-hematocrit tube is heat-sealed as in the determination of the micro-hematocrit of peripheral blood. The tube is centrifuged for 5 minutes at high speed, and then broken at the interface of the erythrocytes and buffy coat. This is accomplished by the use of an ordinary metal file such as is used for cutting glass vials. The buffy coat with the supernatant plasma is expelled on to a coverslip, smeared and stained in the usual manner (Fig.1). This method has proved useful in providing a concentrated preparation of marrow cells and in yielding a more informative picture of the activity of the bone marrow than has been available with the use of ordinary smears.

Determination of Verapamil in Exhaled Breath Condensate by Using Microextraction and Liquid Chromatography

2019 ◽  
Vol 15 (5) ◽  
pp. 535-541 ◽  
Author(s):  
Fariba Pourkarim ◽  
Ali Shayanfar ◽  
Maryam Khoubnasabjafari ◽  
Fariborz Akbarzadeh ◽  
Sanaz Sajedi-Amin ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Exhaled Breath Condensate ◽  
Exhaled Breath ◽  
Good Precision ◽  
Dispersive Liquid Liquid Microextraction ◽  
Breath Condensate ◽  
Liquid Microextraction

Background:Developing a simple analysis method for quantification of drug concentration is one of the essential issues in pharmacokinetic and therapeutic drug monitoring studies.Objective:A fast and reliable dispersive liquid-liquid microextraction procedure was employed for preconcentration of verapamil in exhaled breath condensate (EBC) samples and this was followed by the determination with high-performance liquid chromatography-ultraviolet detection.Methods:A reverse-phase high-performance liquid chromatography (RP-HPLC) combined with a dispersive liquid-liquid microextraction method (DLLME) was applied for quantification of verapamil in the EBC samples. The developed method was validated according to FDA guidelines.Results:Under the optimum conditions, the method provided a linear range between 0.07 and 0.8 µg.mL-1 with a coefficient of determination of 0.998. The intra- and inter-day relative standard deviation and relative error values of the method were below 15%, which indicated good precision and accuracy. The proposed method was successfully applied for the analysis of verapamil in two real samples with concentrations of 0.07 and 0.09 µg.mL-1.Conclusion:The established HPLC-UV-DLLME method could be applied for the analysis of verapamil in human EBC samples.

Determination of Epsilon Aminocaproic Acid Based on Charge Transfer Complexation with p-Nitrophenlol by Spectrophotometry

2020 ◽  
Vol 16 ◽  
Author(s):  
Sheng-Yun Li ◽  
Fang Tian
Keyword(s):  
Charge Transfer ◽  
Aminocaproic Acid ◽  
Concentration Limit ◽  
Official Method ◽  
Good Precision ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
A Charge ◽  
Epsilon Aminocaproic Acid

: A spectrophotometry was investigated for the determination of epsilon aminocaproic acid (EACA) with p-nitrophenol (PNP). The method was based on a charge transfer (CT) complexation of this drug as n-electron donor with π-acceptor PNP. Experiment indicated that the CT complexation was carried out at room temperature for 10 minutes in dimethyl sulfoxide solvent. The spectrum obtained for EACA/PNP system showed the maximum absorption band at wavelength of 425 nm. The stoichiometry of the CT complex was found to be 1:1 ratio by Job’s method between the donor and the acceptor. Different variables affecting the complexation were carefully studied and optimized. At the optimum reaction conditions, Beer’s law was obeyed in a concentration limit of 1～6 µg mL-1. The relative standard deviation was less than 2.9%. The apparent molar absoptivity was determined to be 1.86×104 L mol-1cm-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. The developed method could be applied successfully for the determination of the studied compound in its pharmaceutical dosage forms with a good precision and accuracy compared to official method as revealed by t- and F-tests.

Sampling, Preservation and Counting of Samples II: Zooplankton

2017 ◽  
Author(s):  
Peter H. Wiebe ◽  
Ann Bucklin ◽  
Mark Benfield
Keyword(s):  
Genetic Analysis ◽  
High Speed ◽  
Morphological Analysis ◽  
Taxonomic Composition ◽  
Sampling Techniques ◽  
Sample Analysis ◽  
Sample Preservation ◽  
The Past ◽  
Plankton Collection

This chapter reviews traditional and new zooplankton sampling techniques, sample preservation, and sample analysis, and provides the sources where in-depth discussion of these topics is addressed. The net systems that have been developed over the past 100+ years, many of which are still in use today, can be categorized into eight groups: non-opening/closing nets, simple opening/closing nets, high-speed samplers, neuston samplers, planktobenthos plankton nets, closing cod-end samplers, multiple net systems, and moored plankton collection systems. Methods of sample preservation include preservation for sample enumeration and taxonomic morphological analysis, and preservation of samples for genetic analysis. Methods of analysis of zooplankton samples include determination of biomass, taxonomic composition, and size by traditional methods; and genetic analysis of zooplankton samples.

Adaptation of the AOAC Fluorine Method for Determining Fluoride in Fish Protein Concentrate

1970 ◽  
Vol 53 (1) ◽  
pp. 3-6
Author(s):  
R. Bruce Klemm ◽  
Mary E. Ambrose Klemm
Keyword(s):  
Steam Distillation ◽  
Silica Sand ◽  
Official Method ◽  
Protein Concentrate ◽  
Fish Protein ◽  
Direct Titration ◽  
Modified Method ◽  
Aoac Official ◽  
Aoac Official Method

Abstract The AOAC official method, 24.029–24.035, for the determination of fluorine in foods was modified slightly to o btain quantitative recoveries of fluorine from samples of fish protein concentrate (FPC). The most important alterations include the use of steam distillation, the addition of finely ground silica sand in the distillation, a decrease in the distillation temperature, and the utilization of direct titration. Recoveries of fluoride added to FPC before ashing, using this modified method, averaged 96.0 ± 3.0%. Our results are in agreement with those of several other analysts who used a variety of methods.

Deproteinizing methods evaluated for determination of uric acid in serum by reversed-phase liquid chromatography with ultraviolet detection.

1987 ◽  
Vol 33 (8) ◽  
pp. 1427-1430 ◽  
Author(s):  
R Sakuma ◽  
T Nishina ◽  
M Kitamura
Keyword(s):  
Uric Acid ◽  
Liquid Chromatography ◽  
Perchloric Acid ◽  
High Performance ◽  
Reversed Phase ◽  
Precipitation Method ◽  
Zinc Hydroxide ◽  
Good Precision ◽  
Ultraviolet Detection

Abstract We evaluated six deproteinizing methods for determination of uric acid in serum by "high-performance" liquid chromatography with ultraviolet detection: those involving zinc hydroxide, sodium tungstate, trichloroacetic acid, perchloric acid, acetonitrile, and centrifugal ultrafiltration (with Amicon MPS-1 devices). We used a Toyosoda ODS-120A reversed-phase column. The mobile phase was sodium phosphate buffer (40 mmol/L, pH 2.2) containing 20 mL of methanol per liter. Absorbance of the eluate was monitored at 284 nm. The precipitation method with perchloric acid gave high recoveries of uric acid and good precision, and results agreed with those by the uricase-catalase method of Kageyama (Clin Chim Acta 1971;31:421-6).

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