Use of Constant Temperature and Sodium Borohydride in the Trihydroxyindole Method for Catecholamines

1966 ◽  
Vol 12 (10) ◽  
pp. 659-669 ◽  
Author(s):  
Elizabeth Carlsen Gerst ◽  
Odd S Steinsland ◽  
William W Walcott
Keyword(s):  
Ascorbic Acid ◽  
Constant Temperature ◽  
Sodium Borohydride ◽  
Small Temperature ◽  
Temperature Variations ◽  
Stabilizing Agent ◽  
Fluorescent Analysis

Abstract Small temperature variations during fluorescent analysis with the trihydroxyindole method can introduce significant errors in the measurement of 15µg./L. or less of epinephrine or norepinephrine. To minimize temperature differences, we have devised a simple, constant-temperature system for the Farrand fluorometer. Decomposition of ascorbic acid prior to and during analysis also must be prevented. Sodium borchydride was found to be an effective stabilizing agent that contributes negligible fluorescence.These modifications minimize or eliminate much of the difficulty previously encountered in the use of the trihydroxyindole method.

Synthesis and Characterization of Silver Nanoplates by a Seed-mediated Method

2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Mai Ngọc Tuan Anh
Keyword(s):  
Hydrogen Peroxide ◽  
Silver Nanoparticles ◽  
Ascorbic Acid ◽  
Silver Nitrate ◽  
Sodium Borohydride ◽  
Trisodium Citrate ◽  
Synthesis And Characterization ◽  
Silver Nanoplates ◽  
Seed Mediated

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag\(^+\) ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods.

scholarly journals Simplified Calibration Method for Constant-Temperature Hot-Wire Anemometry

2020 ◽  
Vol 10 (24) ◽  
pp. 9058
Author(s):  
Hidemi Takahashi ◽  
Mitsuru Kurita ◽  
Hidetoshi Iijima ◽  
Seigo Koga
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Constant Temperature ◽  
Calibration Method ◽  
Large Temperature ◽  
Velocity Data ◽  
Hot Wire ◽  
Temperature Variations ◽  
Wire Temperature ◽  
Hot Wire Anemometry

This study proposes a unique approach to convert a voltage signal obtained from a hot-wire anemometry to flow velocity data by making a slight modification to existing temperature-correction methods. The approach was a simplified calibration method for the constant-temperature mode of hot-wire anemometry without knowing exact wire temperature. The necessary data are the freestream temperature and a set of known velocity data which gives reference velocities in addition to the hot-wire signal. The proposed method was applied to various boundary layer velocity profiles with large temperature variations while the wire temperature was unknown. The target flow velocity was ranged between 20 and 80 m/s. By using a best-fit approach between the velocities in the boundary layer obtained by hot-wire anemometry and by the pitot-tube measurement, which provides reference data, the unknown wire temperature was sought. Results showed that the proposed simplified calibration approach was applicable to a velocity range between 20 and 80 m/s and with temperature variations up to 15 °C with an uncertainty level of 2.6% at most for the current datasets.

Calibration of Constant-Temperature Hot-Wire Anemometers at Low Velocities in Water with Variable Fluid Temperature

1972 ◽  
Vol 94 (1) ◽  
pp. 17-22 ◽  
Author(s):  
K. Hollasch ◽  
B. Gebhart
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Constant Temperature ◽  
Fluid Temperature ◽  
Hot Wire ◽  
Temperature Variations ◽  
Wire Probe ◽  
Temperature Mode

Calibration of hot-wire probes operated in a constant-temperature mode in water at low velocities is discussed. Operation under circumstances where natural convection effects are important is considered. A method of calibrating a constant-temperature hot-wire probe for variations in fluid temperature is presented. The method consists of varying wire overheat during calibration at a constant fluid temperature. A relation is derived analytically relating anemometer output with a variable overheat resistance to anemometer output with fluid temperature variations. An experimental study to verify the analysis is presented.

An Automated Trihydroxyindole Procedure for the Differential Analysis of Catecholamines

1965 ◽  
Vol 11 (11) ◽  
pp. 986-997 ◽  
Author(s):  
Robert L Robinson ◽  
Daniel T Watts
Keyword(s):  
Ascorbic Acid ◽  
Aluminum Oxide ◽  
Thioglycolic Acid ◽  
Flow Cell ◽  
Potassium Ferricyanide ◽  
Automatic Analysis ◽  
Differential Analysis ◽  
Stabilizing Agent

Abstract An automated trihydroxyindole procedure for the differential estimation of epinephrine and norepinephrine in tissues, urine, and blood is presented in detail. After an initial purification of the catecholamines by adsorption on aluminum oxide, the neutralized eluates are subjected to automatic analysis, in which potassium ferricyanide and an alkaline stabilizing agent are automatically mixed sequentially with the dialyzed catecholamines. The fluorescent trihydroxyindole derivatives formed are then delivered to a flow cell in a fluorometer and the fluorescence recorded. A differential estimation is obtained by running samples through the system, first with ascorbic acid stabilization to obtain the combined fluorescence of both amines and then with thioglycolic acid stabilization to obtain the fluorescence of norepinephrine alone.

scholarly journals Small temperature variations are a key regulator of reproductive growth and assimilate storage in oil palm (Elaeis guineensis)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Naoki Tani ◽  
Zubaidah Aimi Abdul Hamid ◽  
Natra Joseph ◽  
Othman Sulaiman ◽  
Rokiah Hashim ◽  
...  
Keyword(s):  
Oil Palm ◽  
Elaeis Guineensis ◽  
Reproductive Growth ◽  
Small Temperature ◽  
Temperature Variations

scholarly journals Effect of small temperature variations on the tensile behaviourof Ti-6Al-4V

2011 ◽  
Vol 10 ◽  
pp. 2330-2335 ◽  
Author(s):  
J. Galán López ◽  
J. Peirs ◽  
P. Verleysen ◽  
J. Degrieck
Keyword(s):  
Small Temperature ◽  
Temperature Variations

Green synthesis of a silver nanoparticle–graphene oxide composite and its application for As(iii) detection

RSC Advances ◽  
2014 ◽  
Vol 4 (28) ◽  
pp. 14432-14440 ◽  
Author(s):  
Riyaz Ahmad Dar ◽  
Ninad G. Khare ◽  
Daniel P. Cole ◽  
Shashi P. Karna ◽  
Ashwini Kumar Srivastava
Keyword(s):  
Ascorbic Acid ◽  
Graphene Oxide ◽  
Green Synthesis ◽  
Silver Nanoparticle ◽  
Reducing Agent ◽  
Synthetic Approach ◽  
Stabilizing Agent ◽  
Oxide Composite ◽  
Beta Cyclodextrin

We report a facile and green synthetic approach to synthesize a silver nanoparticle (AgNPs)–graphene oxide (GO) composite using beta cyclodextrin as a stabilizing agent and ascorbic acid as a reducing agent.

The Microstructure of Pure Copper after Stepwise Change of Irradiation Temperature

2005 ◽  
Vol 475-479 ◽  
pp. 1479-1482 ◽  
Author(s):  
Y. Sumino ◽  
H. Watanabe ◽  
Naoaki Yoshida
Keyword(s):  
Temperature Variation ◽  
Constant Temperature ◽  
Temperature Region ◽  
Pure Copper ◽  
Heavy Ion ◽  
Irradiation Temperature ◽  
Temperature Variations ◽  
Stepwise Change ◽  
One Step ◽  
Periodic Temperature

In order to investigate the effect of stepwise change of irradiation temperature on pure copper, heavy ion irradiations under constant temperature and varying temperature conditions were performed. Specimens were irradiated up to 10dpa. In the temperature region of 473K ~ 673K, one-step temperature variation and periodic temperature variations were performed during irradiation. The resulting microstructures were compared with those induced by the irradiation at the constant temperature of 673K.

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