scholarly journals Kinetics of solute leachate from imbibing Caesalpinia echinata Lam. (Brazilwood) seeds

Revista CERES ◽  
2014 ◽  
Vol 61 (1) ◽  
pp. 90-97 ◽  
Author(s):  
Nestor Martini Neto ◽  
Edmir Vicente Lamarca ◽  
Claudio José Barbedo
Keyword(s):  
Seed Coat ◽  
Room Temperature ◽  
Initial Moisture Content ◽  
Leaching Kinetics ◽  
Leaching Rate ◽  
Different Temperatures ◽  
Physiological Quality ◽  
Rapid Tests ◽  
Caesalpinia Echinata ◽  
Kinetics Of

The electrical conductivity of leachates from imbibing seeds has been used as a vigor test for several species. The adaptation of this methodology to different species requires knowledge on the leaching kinetics of electrolytes. For Brazilwood seeds, the classic method was not satisfactory and rapid tests are essential because they have low storage capacity at room temperature. Leaching kinetics during seed imbibition is a function of physiological quality, presence or absence of seed coat, imbibing temperature and the initial moisture content of seed. In this study, the electrolyte leaching rate of six different categories of seeds, from two regions, was evaluated in seeds with and without seed coat and incubated with different moisture contents and at different temperatures. The results showed that the electrolyte leaching rate in Brazilwood seeds is independent of the physiological quality, the presence or absence of seed coat and imbibition temperature, but these factors changed the total amount of electrolytes leached. The leaching rate increased in the first few minutes of imbibition, suggesting that the adjustment of the methodology must consider the reduction in imbibition time, reduction in temperature, use of a controlled and slower pre-imbibition, and replacement of the imbibition solution after the first few minutes.

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).

Study on leaching kinetics of hexavalent chromium from aged calcium-free chromium slag

2021 ◽  
pp. 1-13
Author(s):  
Quan Qi ◽  
Liang Li ◽  
Liangyu Wei ◽  
Baoming Hu ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Resource Utilization ◽  
Scientific Basis ◽  
Diffusion Reaction ◽  
Leaching Kinetics ◽  
Leaching Rate ◽  
Chromium Slag ◽  
Leaching Solution ◽  
Main Components ◽  
Kinetics Of

To provide a scientific basis for the resource utilization of chromium slag, this article studies the release law of hexavalent chromium in the aged calcium-free chromium slag. XRD (X-ray diffractometer) and MLA (Mineral Liberation Analyzer) were used to analyze the composition of the chromium slag; using sulfuric acid-nitric acid as the leaching solution, the release law of hexavalent chromium in chromium slag and the leaching kinetics were studied. The results show that main components of the chromium slag are magnesioferrite, chromite, hematite, hydrargillite, and spinel; chromium is mainly present in chromite and magnesioferrite; the leaching rate of hexavalent chromium increases with the increase of temperature or the decrease of pH. The analysis of leaching kinetics shows the leaching rate is controlled by the internal diffusion reaction, and the apparent activation energy is 11.93 kJ·mol–1. The chromium slag is aged in high temperature seasons, which is conducive to the precipitation of hexavalent chromium in the chromium slag, can increase the yield of chromate in the roasting kiln, and is conducive to resource utilization; chromium slag should be stored in order to prevent acid rain erosion which leads to environmental pollution risk (e.g. drinking water).

scholarly journals Influence of Rolling Temperature on the Perfection Degree of Recrystallization Cube Texture in Nickel

2001 ◽  
Vol 35 (1) ◽  
pp. 1-22 ◽  
Author(s):  
B. K. Sokolov ◽  
I. V. Gervasyeva ◽  
D. P. Rodionov ◽  
Yu. V. Khlebnikova ◽  
I. N. Stepanova ◽  
...  
Keyword(s):  
Room Temperature ◽  
Secondary Recrystallization ◽  
Cube Texture ◽  
Deformation Texture ◽  
Primary Recrystallization ◽  
Pure Nickel ◽  
Rolling Temperature ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Thin Tape

The effect of the rolling temperature on the deformation texture and the perfection degree of a cube texture in pure-nickel thin tape were investigated. The kinetics of primary recrystallization was studied on samples that had undergone rolling at different temperatures and the temperature of the onset of secondary recrystallization was determined. Regularities of the structure formation in the samples are discussed. It is established that the cube texture with the maximum sharpness is produced in the samples rolled at room temperature.

scholarly journals Physiological-biochemical parameters and characteristics of seed coat structure in lupin seeds subjected to long storage at different temperatures

2011 ◽  
Vol 77 (3) ◽  
pp. 201-205 ◽  
Author(s):  
Agnieszka I. Piotrowicz-Cieślak ◽  
Dariusz J. Michalczyk ◽  
Kamila Górska ◽  
Zofia Bulińska-Radomska ◽  
Ryszard J. Górecki
Keyword(s):  
Seed Coat ◽  
Room Temperature ◽  
Seed Storage ◽  
Lupinus Luteus ◽  
Soluble Carbohydrates ◽  
Raffinose Family Oligosaccharides ◽  
Seed Vigour ◽  
Long Term Storage ◽  
Different Temperatures ◽  
Lupin Seeds

Seed vigour, viability, the contents of soluble carbohydrates, total protein, albumins, and globulins, as well as seed coat structure, were analysed in yellow lupin (<em>Lupinus luteus</em> L.) cv. Iryd seeds stored for 20 years at -14<sup>o</sup>C, 0<sup>o</sup>C or at room temperature (approx. +20<sup>o</sup>C). Seed storage at room temperature reduced viability (to 2%) and increased seed leachate electroconductivity. Determinations of total proteins showed that protein content was significantly reduced in seeds stored at +20<sup>o</sup>C compared to the other storage regimens. Raffinose family oligosaccharides were the main soluble carbohydrates in seeds stored at 0<sup>o</sup>C and -14<sup>o</sup>C, whereas sucrose dominated in seeds stored at room temperature. Scanning electron microscopy (SEM) of seed surface and seed coat sections revealed appearance of an amorphic layer on the surface of seeds stored at room temperature (not observed in other seeds) and distinct shrinking of macrosclereid layer in seeds stored at -14<sup>o</sup>C. Macrosclereids layer in all seeds was 100 um thick and accounted for 60% of seed coat thickness. The obtained results suggest that for long term storage of lupin seeds at 0<sup>o</sup>C is the most advisable temperature if both costs of storage and seed storability are considered.

Diffusion of Water in Chestnut Fruits during Drying and Rehydration Processes at Different Temperatures

2008 ◽  
Vol 273-276 ◽  
pp. 758-763
Author(s):  
Ramón Moreira ◽  
Francisco Chenlo ◽  
L. Chaguri ◽  
Christiana Fernandes
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
Convective Drying ◽  
Transfer Processes ◽  
Hot Air ◽  
Mass Transfer Processes ◽  
Different Temperatures ◽  
Diffusional Model ◽  
Kinetics Of

Many food materials must be dried in order to decrease its water activity and to increase the shelf-life. Also, rehydration operation must be carried out as previous step before consumption. Both operations are commonly employed in some industrial chestnut processing. These processes can be carried out at different temperatures and in all cases the quality of the final product can be affected. In this work, convective drying with hot air is the employed method for water removal and rehydration is carried out by immersion of chestnut in water. In both cases, mass transfer processes are governed by water diffusion in the bulk of the solid. The aim of this work is to determine experimentally the drying and rehydration kinetics of chestnut samples at different conditions of temperature and moisture content. Obtained data are modeled with a diffusional model taking into account volume variations and the corresponding values of the coefficients of diffusion of water are obtained. Analysis of the results indicates that drying/rehydration rates increase with temperature and rehydration kinetics are also depending on the initial moisture content of chestnut. Finally, leaching flow during rehydration is only important at high temperature due to starch gelatinization processes.

scholarly journals SEED GERMINATION AND SEEDLING ESTABLISHMENT OF CHERIMOYA (ANNONA CHERIMOLA MILL.) AT DIFFERENT TEMPERATURES

2020 ◽  
Vol 53 (2) ◽  
pp. 185-194
Author(s):  
A. KHELOUFI ◽  
L. M. MANSOURI ◽  
H. KHETTACHE
Keyword(s):  
Seed Germination ◽  
Room Temperature ◽  
Germination Percentage ◽  
Annona Cherimola ◽  
Seedling Length ◽  
Different Temperatures ◽  
External Conditions ◽  
Mean Germination Time ◽  
Coefficient Of Velocity ◽  
Kinetics Of

Cherimoya (Annona cherimola Mill.) has an exceptional flavor and aroma, which makes it a fruit with great potential. However, little is known about its propagation by seeds. According to the scientific literature, the germination of cherimoya seeds is affected much more by external conditions than by internal conditions. Germination of cherimoya variety ‘Concha Lisa’ were tested for germination at constant temperatures of 25, 30, 40°C, and at room temperature, varying from 20-25°C, coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water), for 25 days of incubation. The kinetics of germination was determined according to five closely related parameters, viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG), time to 50% germination (T50) and seedling length (SL). The temperature of 30°C was found optimally suitable with 70.8% FGP, 17.5 days MGT and 3.91 cm SL, while the room temperature of 20-25°C slightly improved germination with only 25% FGP. Furthermore, significant decrease in FGP and SL was observed at 25°C and 40°C of temperature in comparison to 30°C. The analysis also revealed that cherimoya seed germination, day 10-15 after seed sowing is suitable for final counts. An overview on the emergence of cherimoya seedlings, during a 12-week period in pots is presented.

Kinetics of Cu Segregation in Al-Cu(1at% Cu) Interconnects Studied by Resistance Measurements

1997 ◽  
Vol 473 ◽  
Author(s):  
A. J. Kalkman ◽  
A. H. Verbruggen ◽  
G. C. A. M. Janssen ◽  
S. Radelaar
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Grain Boundary ◽  
Room Temperature ◽  
Boundary Diffusion ◽  
Measurement Temperature ◽  
Temperature Range ◽  
Different Temperatures ◽  
Resistance Decrease ◽  
Kinetics Of

ABSTRACTThe time-dependence of the growth of Al2Cu precipitates in Al-Cu(lat% Cu) thin films is studied by means of resistance measurements at different temperatures. The samples are annealed at 400°C for 1 hour, and then quickly cooled down to room temperature. Afterwards, the samples are heated within one minute to a measurement temperature between 140 °C and 240 °C. Growth of precipitates causes a well defined decrease in resistance. The observed resistance decrease does not follow an exponential decay. In the investigated temperature range the resistance decrease can be accurately modelled by (R(t)-R∞) = (Ro-R∞)exp(-(t /τ)n), with the time constant τ= τ0 exp(Ea / kT). Excellent fits were obtained resulting in n = 0.66±0.05, independent of temperature, and Ea= 0.81±0.03 eV. This value for the activation energy agrees very well with the activation energy that has been reported in literature for both electromigration failure in Al-Cu and grain-boundary diffusion of Cu in Al. The value we found for n is intriguingly close to 2/3 and deviates strongly from the values of n reported for bulk Al-Cu (n = 1.5–1.8) in the same temperature range.

Leaching Kinetics of MnO2 from Electrolytic Manganese Anode Slimes in the Presence of SO2

2011 ◽  
Vol 233-235 ◽  
pp. 532-536 ◽  
Author(s):  
Ying Fen Li ◽  
Hua Ye ◽  
Can Cao ◽  
Li Na He
Keyword(s):  
Activation Energy ◽  
Kinetic Equation ◽  
Apparent Activation Energy ◽  
Diffusion Control ◽  
Leaching Kinetics ◽  
Leaching Rate ◽  
Electrolytic Manganese ◽  
Activation Energy For Diffusion ◽  
Partical Size ◽  
Kinetics Of

Thepaper describes the kinetics of MnO2from electrolytic manganese (EM) anode slimesleached by SO2.The effects of stirring speed,SO2concentration,temperature, and partical size on the leaching rate of manganese are discussed. Experimental results indicated that the leaching of MnO2by SO2is 0.86 order with respect to SO2concentration. The apparent activation energy values for re-action is 25.7KJ/mol,which is consist with the values of activation energy for diffusion control. The kinetic equation can be expressed as: 1-(2/3)x-(1-x)^2/3=(k1/ρr){[SO2]0.86exp(-25700/RT)}t. Meanw-hile, comparative experiments were operated, using analytical class MnO2and pyrolusite, the differ-ence among the three MnO2simples reaction with SO2was identified.

Leaching Kinetics of Gold Involved in the System S2O32--EDTA-Cu2+

2020 ◽  
Vol 1001 ◽  
pp. 212-218
Author(s):  
Peng Zhi Xiang ◽  
Chao Deng ◽  
Huang Yao ◽  
Long Jiang Liu ◽  
S. Mogdal
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Reaction Order ◽  
Effect Of Temperature ◽  
Leaching Kinetics ◽  
Leaching Rate ◽  
Gold Ores ◽  
Remarkable Effect ◽  
Copper Addition ◽  
A Value ◽  
Kinetics Of

Thiosulphate gold leaching is an alternative technology to the cyanidation of gold ores. Ethylenediaminetetraacetic acid is referred to as EDTA.A study on the leaching kinetics of gold involved in the system S2O32--EDTA-Cu2+ for the gold in this paper. The effect of temperature and of the addition of copper has been also analyzed, temperature has a remarkable effect over the overall reaction rate in the range from 293 to 323k, the result shows that the leaching process conforms to the chemical control model. The concentration of [S2O32-] considerably affects the leaching rate obtaining a value of for the order of reaction in the range of concentrations from 0.05 to 0.3 mol/L of S2O32- which obtaining a reaction order of 1.029. Copper addition favored the leaching rate of gold which obtaining a reaction order of 0.441,Thiosulphater addition also favored the leaching rate of gold .kinetics model was established which is 1−(1−x)1/3=4950.8c (S2O32-)1.029c (Cu2+)0.441exp (-9911/8.314T).

Leaching Kinetics and Seperation of Antimony and Arsenic from Arsenic Alkali Residue

2011 ◽  
Vol 402 ◽  
pp. 57-60 ◽  
Author(s):  
Gui Sheng Zeng ◽  
Hui Li ◽  
Su Hua Chen ◽  
Xin Man Tu ◽  
Wen Bin Wang
Keyword(s):  
Shrinking Core Model ◽  
Leaching Kinetics ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Kinetics Equation ◽  
Surface Chemical Reaction ◽  
Liquid Ratio ◽  
Shrinking Core ◽  
Solid Liquid ◽  
Kinetics Of

The separation of antimony and arsenic and leaching kinetics of arsenic from arsenic alkali residue were investigated. The influencing factors such as solid/liquid ratio, stir speed, temperature and time on leaching of arsenic were studied. The results show that the leaching rate reaches 87.75% at the condition of solid/liquid ratio of 1:4 , stir speed of 600r/min ,temperature of 90°C and time of 60min. The leaching process was controlled by the surface chemical reaction and the kinetics of leaching arsenic followed the model of shrinking core. The activation energy was found to be 666.57kJ/mol. The kinetics equation was expressed as shrinking core model.

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