Heat Degradation Kinetics of the Chlorophyll from Spinach and its Correlation with the Reflection Spectra

2017 ◽  
Vol 68 (4) ◽  
pp. 830-834 ◽  
Author(s):  
Elena Corina Popescu ◽  
Claudia Lavinia Buruleanu
Keyword(s):  
Chlorophyll A ◽  
Degradation Kinetics ◽  
Measuring Method ◽  
Reflection Spectra ◽  
Chlorophyll B ◽  
Non Invasive ◽  
Heat Degradation ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Spinach Leaves

Chlorophyll, the pigment responsible for the green color specific to the spinach leaves, is sensitive to temperature, pH, activity of enzymes. The heat degradation kinetics of the chlorophyll a and chlorophyll b from the spinach leaves was studied at different temperatures (60, 70, 80 and 900C) and different times (3, 9, 12, 15 min). The degradation of the chlorophyll a and chlorophyll b followed a first-order reaction, and the rate constant had values between 0.0199-0.0695 min-1 for chlorophyll a and 0042 -0.011 min-1 for chlorophyll b respectively. The dependence between the chlorophyll degradation and temperature was modeled using the Arrhenius�a equation. The activation energy was by 44.316 Kjmol-1 for chlorophyll a and 35.384 Kjmol-1 for chlorophyll b respectively. Using the rapid, non-invasive measuring method of the reflection spectra in red band and in NIR region and the calculation of the index Clred edge, the chlorophyll quantity from spinach leaves was measured with a relative error ErCle between 1.27 and 8.65%.

scholarly journals Degradation Kinetics of Anthocyanins in Shalgam Beverage

2019 ◽  
Vol 7 (2) ◽  
pp. 282
Author(s):  
Adnan Bozdoğan ◽  
Kurban Yaşar
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Half Life ◽  
Degradation Kinetics ◽  
Production Method ◽  
Order Reaction ◽  
Different Temperatures ◽  
Traditional Production ◽  
Effects Of Temperature ◽  
Kinetics Of

This research was performed to elucidate the effects of temperature on the degradation kinetics of anthocyanins in shalgam beverage. Shalgam beverage was produced according to traditional production method. Then, it was kept at three different temperatures (65°C, 75°C, and 85°C) for 12 hours, and the relevant quantities of anthocyanins were determined thereafter. The research revealed that degradation of the anthocyanins was well described with a 1st-order reaction kinetics model and the R2 values varied in the range of 0.9059-0.9715. Activation energy of the reaction was determined to be 48537 Joule/mole. The half-lives of anthocyanins at 65°C and 75° C, and 85°C were found to be 138.63, 136.72, and 51.57, respectively. Compared the half-life periods at different temperatures, anthocyanins were found to be more resistant at 65°C and 75°C than at 85°C.

scholarly journals The Toxicological Testing and Thermal Decomposition of Drive and Transport Belts Made of Thermoplastic Multilayer Polymer Materials

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2232 ◽  
Author(s):  
Piotr Krawiec ◽  
Łukasz Warguła ◽  
Daniel Małozięć ◽  
Piotr Kaczmarzyk ◽  
Anna Dziechciarz ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Degradation Kinetics ◽  
Combustion Products ◽  
Polymer Materials ◽  
Toxic Substances ◽  
Butadiene Rubber ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
In Fire ◽  
Kinetics Of

The article presents the potential impact of flat drive and transport belts on people’s safety during a fire. The analysis distinguished belts made of classically used fabric–rubber composite materials reinforced with cord and currently used multilayer polymer composites. Moreover, the products’ multilayers during the thermal decomposition and combustion can be a source of emissions for unpredictable and toxic substances with different concentrations and compositions. In the evaluation of the compared belts, a testing methodology was used to determine the toxicometric indicators (WLC50SM) on the basis of which it was possible to determine the toxicity of thermal decomposition and combustion products in agreement with the standards in force in several countries of the EU and Russia. The analysis was carried out on the basis of the registration of emissions of chemical compounds during the thermal decomposition and combustion of polymer materials at three different temperatures. Moreover, the degradation kinetics of the polymeric belts by using the thermogravimetric (TGA) technique was evaluated. Test results have shown that products of thermal decomposition resulting from the neoprene (NE22), leder leder (LL2), thermoplastic connection (TC), and extra high top cower (XH) belts can be characterized as moderately toxic or toxic. Their toxicity significantly increases with the increasing temperature of thermal decomposition or combustion, especially above 450 °C. The results showed that the belts made of several layers of polyamide can be considered the least toxic in fire conditions. The TGA results showed that NBR/PA/PA/NBR belt made with two layers of polyamide and the acrylonitrile–butadiene rubber has the highest thermal stability in comparison to other belts.

scholarly journals The kinetics of photosynthesis

1935 ◽  
Vol 149 (868) ◽  
pp. 596-596 ◽  
Keyword(s):  
Chlorophyll A ◽  
Reduction Reaction ◽  
Chlorophyll B ◽  
Primary Reaction ◽  
External Concentration ◽  
Photostationary State ◽  
Oxidation Reduction ◽  
Oxidation Reduction Reaction ◽  
Rate Of Photosynthesis ◽  
Kinetics Of

It has been proved that the primary process in photosynthesis is an oxidation-reduction reaction. Expressing this in the simplest terms of chlorophyll, a complex of chlorophyll A and hydrated CO 2 is converted by the action of light into chlorophyll B and activated formaldehyde which at once undergoes polymerization into hexoses. The chlorophyll B thereby produced undergoes the dark or Blackman reaction and is reduced to chlorophyll A. There are, therefore, three separate processes involved in the photosynthetic cycle, namely, the primary photosynthetic reaction, the Blackman reaction, and the formation of the photosensitive complex of chlorophyll A and hydrated CO 2 . Since the Blackman reaction regenerates chlorophyll A from the chlorophyll B produced in the primary reaction, a photostationary state will be established which is determined by the intensity of irradiation, the temperature and the external concentration of hydrated CO 2 . In this communication the equation for the photostationary state is derived, and shown to express correctly the variation in the rate of photosynthesis with temperature.

Degradation Kinetics Study of Alogliptin Benzoate in Alkaline Medium by Validated Stability-Indicating HPTLC Method

2016 ◽  
Vol 99 (6) ◽  
pp. 1505-1512
Author(s):  
Kunjan Bharatkumar Bodiwala ◽  
Shailesh Shah ◽  
Jeenal Thakor ◽  
Bhavin Marolia ◽  
Pintu Prajapati
Keyword(s):  
Alkaline Medium ◽  
High Performance ◽  
Degradation Kinetics ◽  
Quantitative Estimation ◽  
Solvent System ◽  
Stability Indicating ◽  
Validation Parameters ◽  
Different Temperatures ◽  
Contour Plots ◽  
Kinetics Of

Abstract A rapid, sensitive, and stability-indicating high-performance thin-layer chromatographic method was developed and validated to study degradation kinetics of Alogliptin benzoate (ALG) in an alkaline medium. ALG was degraded under acidic, alkaline, oxidative, and thermal stress conditions. The degraded samples were chromatographed on silica gel 60F254-TLC plates, developed using a quaternary-solvent system (chloroform–methanol–ethyl acetate–triethyl amine, 9+1+1+0.5, v/v/v/v), and scanned at 278 nm. The developed method was validated per International Conference on Harmonization guidelines using validation parameters such as specificity, linearity and range, precision, accuracy, LOD, and LOQ. The linearity range for ALG was 100–500 ng/band (correlation coefficient = 0.9997) with an average recovery of 99.47%. The LOD and LOQ for ALG were 9.8 and 32.7 ng/band, respectively. The developed method was successfully applied for the quantitative estimation of ALG in its synthetic mixture with common excipients. Degradation kinetics of ALG in an alkaline medium was studied by degrading it under three different temperatures and three different concentrations of alkali. Degradation of ALG in the alkaline medium was found to follow first-order kinetics. Contour plots have been generated to predict degradation rate constant, half-life, and shelf life of ALG in various combinations of temperature and concentration of alkali using Design Expert software.

scholarly journals Degradation Kinetics and Shelf Life of N-acetylneuraminic Acid at Different pH Values

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5141
Author(s):  
Weiwei Zhu ◽  
Xiangsong Chen ◽  
Lixia Yuan ◽  
Jinyong Wu ◽  
Jianming Yao
Keyword(s):  
Shelf Life ◽  
Degradation Kinetics ◽  
Polysialic Acid ◽  
Acetylneuraminic Acid ◽  
Ph Values ◽  
Different Temperatures ◽  
Shelf Life Studies ◽  
The Stability ◽  
Kinetics Of ◽  
Hydrolysis Of

The objective of this study was to investigate the stability and degradation kinetics of N-acetylneuraminic acid (Neu5Ac). The pH of the solution strongly influenced the stability of Neu5Ac, which was more stable at neutral pH and low temperatures. Here, we provide detailed information on the degradation kinetics of Neu5Ac at different pH values (1.0, 2.0, 11.0 and 12.0) and temperatures (60, 70, 80 and 90 °C). The study of the degradation of Neu5Ac under strongly acidic conditions (pH 1.0–2.0) is highly pertinent for the hydrolysis of polysialic acid. The degradation kinetics of alkaline deacetylation were also studied. Neu5Ac was highly stable at pH 3.0–10.0, even at high temperature, but the addition of H2O2 greatly reduced its stability at pH 5.0, 7.0 and 9.0. Although Neu5Ac has a number of applications in products of everyday life, there are no reports of rigorous shelf-life studies. This research provides kinetic data that can be used to predict product shelf lives at different temperatures and pH values.

scholarly journals Aspect of the degradation and adsorption kinetics of atrazine and metolachlor in andisol soil

2017 ◽  
Vol 10 (1) ◽  
pp. 1-14 ◽  
Author(s):  
P. Jaikaew ◽  
F. Malhat ◽  
J. Boulange ◽  
H. Watanabe
Keyword(s):  
Degradation Kinetics ◽  
Field Capacity ◽  
Order Model ◽  
Freundlich Isotherms ◽  
Adsorption Behaviors ◽  
Different Temperatures ◽  
Equilibrium Process ◽  
Kinetics Of ◽  
Sorption Study ◽  
Sorption Characteristics

SummaryThe degradation kinetics and sorption characteristics of atrazine and metolachlor in Japanese andisol soil were evaluated using laboratory incubation of soil samples. The water content of the soil was set to field capacity while three different temperatures (5, 25 and 35°C) were considered for the experiment. First order model fitted the degradation kinetics of both herbicides under the investigated temperature range with half-lives ranging from 19.2 to 46.9 days for atrazine and from 23.4 to 66.9 days for metolachlor, respectively. The activation energies (Ea) of atrazine and metolachlor calculated using Arhenius equation were 21.47 and 23.91 kJ mol−1, respectively. The soil sorption study was conducted using the batch equilibrium process. The adsorption behaviors of atrazine and metolachlor were investigated using linear, Freundlich and Langmuir isotherms although the linear and Freundlich isotherms gave relatively high correlation coefficient (R2) and very low standard error of estimate (SEE). The free energy (ΔG°) values were in the range −30.6 to −32.0 kJ/mol, and −32.1 to −41.5 kJ/mol for atrazine and metolachlor, respectively. Thermodynamic parameters indicated that the adsorption is spontaneous, endothermic accompanied by increase in entropy. The understanding of atrazine and metolachlor sorption processes is essential to determine the pesticide fate and availability in soil for pest control, biodegradation, runoff and leaching.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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