Extraction of Dithiocarbamate Chelates of Ni(II), Cu(II), Zn(II)

1996 ◽  
Vol 61 (5) ◽  
pp. 673-680
Author(s):  
Drahomír Oktavec ◽  
Jozef Lehotay ◽  
Viktor Vrábel ◽  
Elena Korgová
Keyword(s):  
Strong Acid ◽  
Optimum Conditions ◽  
Time Intervals ◽  
Acid Media ◽  
Ph Values ◽  
Quantitative Extraction ◽  
Maximum Extraction ◽  
Short Time ◽  
Alkali Salts ◽  
Acid Region

Extraction has been investigated of chelates of alkali salts of dithiocarbamic (DTC) acids derived from (R-) dimethyl-, diethyl-, dipropyl-, diisopropyl-, dibutyl-, diisobutyl-, dipentyl-, and dihexylamine, piperidine, and morpholine with Ni(II), Cu(II), and Zn(II) from aqueous solutions of various pH values into chloroform for various time intervals. The optimum conditions have been determined for the maximum extraction yields of the metal connected with the minimum extraction yields of excess DTC ligand. The extraction of DTC chelates of Ni(II), Cu(II), and Zn(II) is best accomplished in a reaction period of 4.5 min in strong acid region (Ni, Cu) or in alkaline region with buffers of pH 8.5-9.0 (Zn). The advantage of DTC as compared with many other reagents lies in the possibility of quantitative extraction of Ni(II) and Cu(II) from strong acid media since in this region the excess DTC ligand is completely decomposed to carbon disulfide and amine in short time, and thus it does not interfere with the subsequent spectrophotometric determination.

Proposal of PV Output Estimate Method in Short Time Intervals

2016 ◽  
Vol 136 (12) ◽  
pp. 891-897 ◽  
Author(s):  
Katsuhiro Matsuda ◽  
Kazuhiro Misawa ◽  
Hirotaka Takahashi ◽  
Kenta Furukawa ◽  
Satoshi Uemura
Keyword(s):  
Time Intervals ◽  
Estimate Method ◽  
Short Time

EVALUATION OF SHORT TIME INTERVALS IN NORMAL AGING AND LATE-LIFE DEPRESSIONS

2020 ◽  
pp. 54-69
Author(s):  
Elena Yu. Balashova ◽  
◽  
Lika I. Mikeladze ◽  
Elena K. Kozlova ◽  
◽  
...  
Keyword(s):  
Late Life ◽  
Normal Aging ◽  
Time Intervals ◽  
Short Time

Investigating the Antioxidant Potential of Garlic (Allium sativum) Extracts Through Different Extraction Modes

2019 ◽  
Vol 15 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Kanza A. Awan ◽  
Masood S. Butt ◽  
Iahtisham Ul Haq ◽  
Hafiz A.R. Suleria
Keyword(s):  
Allium Sativum ◽  
Total Phenolics ◽  
Methanolic Extract ◽  
Antioxidant Potential ◽  
Flavonoid Content ◽  
Time Intervals ◽  
Methanolic Extracts ◽  
Maximum Extraction ◽  
Acid Potential ◽  
The Ideal

Background: Garlic (Allium sativum) possesses health enhancing abilities due to the presence various phytoceutics moities. The current research was deigned to explore the phytochemicals and antioxidant capacity of Pakistani garlic. Methods: Garlic extracts were obtained using methanol, hexane and ethyl acetate at different time intervals (35, 50 and 65 min) followed by their polyphenols and flavonoid content determination. Afterwards, the antioxidant potential was also determined. Results: The outcomes revealed that the methanolic extracts obtained at 50 min extraction time showed maximum total phenolics as 60.38±0.23 mg GAE/100g and flavonoids as 58.45±1.24 mg/100g. Similarly, the highest DPPH activity (61.59±1.58%) and β-carotene and linoleic acid potential (64.96±1.72%) were also observed for methanolic extract. Conclusion: Inferences were made that Pakistani garlic contains myriad of phenolics and flavonoids but the extraction of these components depends upon the solvent/time combination. In this study, methanol proved to be the ideal solvent for the maximum extraction of phytochemicals from garlic.

scholarly journals Neural Network Approach for Global Solar Irradiance Prediction at Extremely Short-Time-Intervals Using Particle Swarm Optimization Algorithm

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1213
Author(s):  
Ahmed Aljanad ◽  
Nadia M. L. Tan ◽  
Vassilios G. Agelidis ◽  
Hussain Shareef
Keyword(s):  
Neural Networks ◽  
Particle Swarm Optimization ◽  
Solar Irradiance ◽  
Particle Swarm ◽  
Time Interval ◽  
Time Intervals ◽  
Swarm Optimization ◽  
Backpropagation Neural Networks ◽  
Proposed Model ◽  
Short Time

Hourly global solar irradiance (GSR) data are required for sizing, planning, and modeling of solar photovoltaic farms. However, operating and controlling such farms exposed to varying environmental conditions, such as fast passing clouds, necessitates GSR data to be available for very short time intervals. Classical backpropagation neural networks do not perform satisfactorily when predicting parameters within short intervals. This paper proposes a hybrid backpropagation neural networks based on particle swarm optimization. The particle swarm algorithm is used as an optimization algorithm within the backpropagation neural networks to optimize the number of hidden layers and neurons used and its learning rate. The proposed model can be used as a reliable model in predicting changes in the solar irradiance during short time interval in tropical regions such as Malaysia and other regions. Actual global solar irradiance data of 5-s and 1-min intervals, recorded by weather stations, are applied to train and test the proposed algorithm. Moreover, to ensure the adaptability and robustness of the proposed technique, two different cases are evaluated using 1-day and 3-days profiles, for two different time intervals of 1-min and 5-s each. A set of statistical error indices have been introduced to evaluate the performance of the proposed algorithm. From the results obtained, the 3-days profile’s performance evaluation of the BPNN-PSO are 1.7078 of RMSE, 0.7537 of MAE, 0.0292 of MSE, and 31.4348 of MAPE (%), at 5-s time interval, where the obtained results of 1-min interval are 0.6566 of RMSE, 0.2754 of MAE, 0.0043 of MSE, and 1.4732 of MAPE (%). The results revealed that proposed model outperformed the standalone backpropagation neural networks method in predicting global solar irradiance values for extremely short-time intervals. In addition to that, the proposed model exhibited high level of predictability compared to other existing models.

scholarly journals Optimal Perturbations of an Oceanic Vortex Lens

Fluids ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 63 ◽  
Author(s):  
Thomas Meunier ◽  
Claire Ménesguen ◽  
Xavier Carton ◽  
Sylvie Le Gentil ◽  
Richard Schopp
Keyword(s):  
Normal Mode ◽  
Growth Rates ◽  
Time Interval ◽  
Time Intervals ◽  
Horizontal Structure ◽  
Azimuthal Wave ◽  
Wave Numbers ◽  
Non Linear ◽  
Long Time ◽  
Short Time

The stability properties of a vortex lens are studied in the quasi geostrophic (QG) framework using the generalized stability theory. Optimal perturbations are obtained using a tangent linear QG model and its adjoint. Their fine-scale spatial structures are studied in details. Growth rates of optimal perturbations are shown to be extremely sensitive to the time interval of optimization: The most unstable perturbations are found for time intervals of about 3 days, while the growth rates continuously decrease towards the most unstable normal mode, which is reached after about 170 days. The horizontal structure of the optimal perturbations consists of an intense counter-shear spiralling. It is also extremely sensitive to time interval: for short time intervals, the optimal perturbations are made of a broad spectrum of high azimuthal wave numbers. As the time interval increases, only low azimuthal wave numbers are found. The vertical structures of optimal perturbations exhibit strong layering associated with high vertical wave numbers whatever the time interval. However, the latter parameter plays an important role in the width of the vertical spectrum of the perturbation: short time interval perturbations have a narrow vertical spectrum while long time interval perturbations show a broad range of vertical scales. Optimal perturbations were set as initial perturbations of the vortex lens in a fully non linear QG model. It appears that for short time intervals, the perturbations decay after an initial transient growth, while for longer time intervals, the optimal perturbation keeps on growing, quickly leading to a non-linear regime or exciting lower azimuthal modes, consistent with normal mode instability. Very long time intervals simply behave like the most unstable normal mode. The possible impact of optimal perturbations on layering is also discussed.

An Automatic Paperless Velocity Measuring and Recording System

2014 ◽  
Vol 889-890 ◽  
pp. 745-748
Author(s):  
Jian Sheng Cao ◽  
Wan Jun Zhang ◽  
Xin Hua Zeng
Keyword(s):  
Flow Velocity ◽  
Optical Pulse ◽  
Electric Pulse ◽  
Automatic Monitoring ◽  
Time Intervals ◽  
Stream Flows ◽  
Fluid Flow Velocity ◽  
Photoelectric Sensor ◽  
Velocity Measuring ◽  
Short Time

Automatic monitoring of hydrologic properties such as water velocity at short-time intervals is critical for understanding watershed eco-hydrological processes. This can also be used to study the laws of stream flows and interactions ecological process. The advent of modern electronic technology (and the near-perfection of especially sensor and data collection technologies), has made it possible to use automatic monitoring systems to continuously measure hydrologic properties at short-time intervals. This paper introduces one such paperless flow velocity measuring/recoding system. The system uses a photoelectric sensor that is mainly comprised of photoelectric velocity sensor and pulse recorder. The system uses propellers (with reflective panels and photoemission cells) to transform flow velocities into optical pulse signals. It also uses photosensitive tubes to transform optical pulse signals into electric pulse signals. The electric pulse counts (generated in unit time) are recorded via pulse recorders. This therefore accomplishes automatic monitoring and continuous recording of fluid flow velocity.

Rearrangement of 1-acylaziridines to oxazolinium cations in strong acid media

1970 ◽  
Vol 35 (4) ◽  
pp. 1187-1190 ◽  
Author(s):  
Charles U. Pittman ◽  
Samuel P. McManus
Keyword(s):  
Strong Acid ◽  
Acid Media

scholarly journals Aferição do pH de diferentes agentes clareadores indicados para o clareamento intracoronário

2018 ◽  
Author(s):  
João Felipe Besegato ◽  
Gabriela Dos Santos Ribeiro Rocha ◽  
Marlene De Sousa Amorim ◽  
Fabio Martins Salomão ◽  
Daniel Poletto ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Statistical Analysis ◽  
Multiple Comparisons ◽  
The Other ◽  
Sodium Perborate ◽  
Distilled Water ◽  
Friedman Test ◽  
Time Intervals ◽  
Ph Values ◽  
Evaluation Time

Objective: to measure pH values of bleaching agents that are indicated to intracoronal bleaching technique in different time intervals. Methods: Each group (G) received five samples (n=5): G1 – distilled water (AD); G2 – hydrogen peroxide (H2O2) 30%; G3 – sodium perborate (PbS) + AD; G4 – PbS + H2O2 30%; G5 – sodium percarbonate (PcS) + AD; and G6 – PcS + H2O2 30%. pH values were stated using a digital pHmeter, in different time intervals: immediately after handling (T0), 24 hours (T1) and 168 hours after handling (T2). The results were submitted to statistical analysis through Kruskal-Wallis and Mann Whitney tests, in this order, allowing multiple comparisons among the groups. To verify the effect of time in each group, Friedman test was applied. Results: In the evaluation of the effect of time in each group, it was observed that G2 presented acid behavior, while the other groups exhibited values close to neutrality or alkaline. Conclusions: H2O2 30% was the only agent that showed acidic behavior in every evaluation time. Meanwhile, PcS + H2O had the highest pH values.

Kinetics and mechanism of the formation of methacrylamide from 2-methyl-2-sulphatopropionamide in strong acid media

1991 ◽  
pp. 417 ◽  
Author(s):  
C. Dennis Hall ◽  
Christopher J. Leeding ◽  
Stephen Jones ◽  
Stephen Case-Green ◽  
Ian Sanderson ◽  
...  
Keyword(s):  
Strong Acid ◽  
Kinetics And Mechanism ◽  
Acid Media
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