scholarly journals Chemical Stability of the Fertilizer Chelates Fe-EDDHA and Fe-EDDHSA over Time

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1933
Author(s):  
Ewelina Klem-Marciniak ◽  
Marta Huculak-Mączka ◽  
Kinga Marecka ◽  
Krystyna Hoffmann ◽  
Józef Hoffmann
Keyword(s):  
Aqueous Medium ◽  
Chemical Stability ◽  
Environmental Parameters ◽  
Ion Pair ◽  
Iron Chelates ◽  
Ph Values ◽  
Ion Pair Chromatography ◽  
Time Changes ◽  
The Stability ◽  
Over Time

In application conditions, the influence of environmental parameters on used fertilizer chelates and their distribution over time is important. For this purpose, the changes in the content of micronutrient ions and Fe-EDDHA and Fe-EDDHSA chelates in an aqueous medium at different pH values were studied. In the assumed time, changes in the ions content were analyzed using the voltammetry method at pH 3, 5 and 7. The content of isomers and chelate forms was analyzed by ion pair chromatography at pH 3, 5 and 7. These studies allowed us to determine the effect of pH on the stability of iron chelates over time.

scholarly journals Evaluation of Cardiac Thrombus Stability based on Contrast-Enhanced Echocardiography：Research Protocol and Preliminary Results

2021 ◽  
Author(s):  
Ying Li ◽  
Xin Wang ◽  
Weidong Ren ◽  
Yangjie Xiao ◽  
Xiaona Yu ◽  
...  
Keyword(s):  
Scoring System ◽  
Shear Wave Elastography ◽  
Progressive Increase ◽  
Cardiac Thrombus ◽  
Contrast Enhanced ◽  
Study Results ◽  
Time Changes ◽  
The Stability ◽  
Over Time

Abstract Objective: This study attempted to test a new scoring system for evaluating the stability of cardiac thrombi using contrast-enhanced ultrasound (CEUS). Methods: We used human whole blood to make the thrombus model in vitro which were divided into 2 groups, the 1-hour (T1h) and 7-day (T7d) group. The T1h group was monitored for 1 hour continuously to observe for the formation of a new thrombus on the original thrombus base. Over time, changes in CEUS images and pathology and shear wave elastography (SWE) of thrombus were observed in theT1h and T7 groups. Twenty-eight adult patients diagnosed with a cardiac thrombus were selected and examined by transthoracic echocardiography (TTE) and CEUS. Thrombi were scored for substrate (Ts) and hardness (Th) based on the visualized degree of contrast penetration into the thrombus. The Ts and Th were statistically analyzed for thrombolytic time and the risk of embolism to other organs. Results: In vitro, pathology revealed a decreased pore structure; further, the average Young’s modulus of the thrombi over time indicated a progressive increase in hardness. Contrast-enhancing agents were able to enter a fresh, loose thrombus, but were not able to enter a chronic, stable thrombus. With increasing Ts and Th, thrombolytic time was prolonged, and the risk of embolism to other organs was increased. Conclusions: Our study results suggest that this new CEUS scoring system can evaluate the hardness of a cardiac thrombus and the quality of its underlying substrate; this allows for quantitative evaluation of thrombus stability.

scholarly journals Comparison of stability properties of poly(acrylic acid) adsorbed on the surface of silica, alumina and mixed silica-alumina nanoparticles — application of turbidimetry method

2014 ◽  
Vol 12 (4) ◽  
pp. 476-479 ◽  
Author(s):  
Małgorzata Wiśniewska ◽  
Teresa Urban ◽  
Agnieszka Nosal-Wiercińska ◽  
Vladimir Zarko ◽  
Vladimir Gun’ko
Keyword(s):  
Acrylic Acid ◽  
Colloidal Suspensions ◽  
Alumina Nanoparticles ◽  
Solution Ph ◽  
Ph Values ◽  
Silica Alumina ◽  
Effective Stabilizer ◽  
The Stability ◽  
Over Time ◽  
Poly Acrylic Acid

AbstractThe influence of anionic poly(acrylic acid) — PAA addition on the stability of synthesized silica, alumina and mixed silica-alumina suspensions as a function of solution pH was studied. The turbidimetry method was used to monitor the changes of the examined systems stability over time. The calculated stability coefficients enabled estimation of polymer adsorption influence on stability of metal oxide suspension. It was shown that the alumina suspension without the polymer is the most unstable at the pH values 6 and 9, whereas the silica polymer was most unstable at pH 3. PAA with higher molecular weight (240 000) is a relatively effective stabilizer of all investigated adsorbents (except silica at pH 3). These properties of poly(acrylic acid) are highly desirable in many branches of industry (e.g. production of cosmetics, pharmaceuticals, paints) where polymers are widely used as effective stabilizers of colloidal suspensions.

The optimal extraction and stability of atranorin from lichens, in relation to solvent and pH

2018 ◽  
Vol 50 (4) ◽  
pp. 499-512 ◽  
Author(s):  
Carlo VOS ◽  
Phillip MCKINNEY ◽  
Colby PEARSON ◽  
Erik HEINY ◽  
Gamini GUNAWARDENA ◽  
...  
Keyword(s):  
Hplc Analysis ◽  
Metabolic Response ◽  
Strong Acid ◽  
Strong Base ◽  
Ph Values ◽  
Extraction Solvents ◽  
Acidic Conditions ◽  
The Stability ◽  
Future Work ◽  
Over Time

AbstractAtranorin is a secondary metabolite found in many lichens. This compound can act as a photo-buffer, supporting its use as a marker of metabolic response to changes in light. In preliminary trials, atranorin was found to be unstable over time when in solution, potentially precluding its usefulness in this capacity. The present study tests the stability of atranorin in different extraction solvents and at different pH values over time using HPLC analysis. We found that atranorin is most stable in acetonitrile, among six tested solvents, and that the presence of strong acid or a strong base destabilizes the compound. We propose that atranorin breaks down through transesterification in methanol and ethanol until an equilibrium is reached, while a strong base breaks down atranorin through saponification and under acidic conditions, atranorin concentration significantly increases with time. Although atranorin levels were found to be stable in whole thallus extracts from fresh lichens using a leaching method, chemicals isolated using chromatographic separation showed similar breakdown to an atranorin standard. In future work on lichens atranorin should be extracted in acetonitrile or acetone without an added base or acid to yield the greatest stability and thus provide more accurate concentration values of atranorin with time using HPLC. The interactions of atranorin with acid and with chloroform need further study.

Reverse-phase chromatography of polar biological substances: separation of catechol compounds by high-performance liquid chromatography.

1976 ◽  
Vol 22 (9) ◽  
pp. 1497-1502 ◽  
Author(s):  
I Molnár ◽  
C Horváth
Keyword(s):  
High Performance ◽  
Hydrophobic Interactions ◽  
Clinical Analysis ◽  
Ion Pair ◽  
Reverse Phase ◽  
Reverse Phase Chromatography ◽  
Degree Of Dissociation ◽  
Ion Pair Chromatography ◽  
Relative Retention ◽  
The Stability

Abstract Catecholamines and their metabolites have been separated isocratically by reverse-phase chromatography with aqueous (no organic solvent admixed) eluents. Unlike ion-exchange or ion-pair chromatography, mixtures of both acidic and basic substances can be separated in a single chromatographic run, because the retention is governed by hydrophobic interactions between the nonpolar moiety of the solute molecules and the octadecyl-silica stationary phase. The relative retention values strongly depend on the pH of the eluent, which governs the degree of dissociation of ionogenic solutes. The reproducibility of the results and the stability and efficiency of the chromatographic systems make this approach particularly attractive for use in clinical analysis.

scholarly journals Synthesis And Characterization Of SiO2, SnO2 And TiO2 Metal Oxide Shells Covering Cu2O Particles

2015 ◽  
Vol 60 (2) ◽  
pp. 1159-1163 ◽  
Author(s):  
Ri Yu ◽  
Jiyeon Yun ◽  
Yoojin Kim
Keyword(s):  
Synthesis And Characterization ◽  
Colloidal Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ph Values ◽  
Coated Nanoparticles ◽  
Transmission Electron ◽  
The Stability ◽  
Over Time

Abstract In this work is described a means of improving the chemical stability of Cu2O@SiO2, Cu2O@SnO2 and Cu2O@TiO2 materials. The SiO2, SnO2 and TiO2 coated samples were stable from pH 3 to pH 10 for up to seven days. To determine the stability of the coated nanoparticles, and their colloidal solutions under acidic and basic conditions, colloidal nanoparticle solutions with various pH values were prepared and monitored over time. Details of the effect of variations in pH on the phase stability of core-shell type Cu2O were characterized using transmission electron microscopy and X-ray diffraction.

scholarly journals Effects of magnesium impregnation on stability and sorption performance of biochar derived from sawdust and corn husks

BioResources ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 289-301
Author(s):  
Zhao Xu ◽  
Ting Chen ◽  
Zhuhong Ding ◽  
Xin Hu ◽  
Guangze Nie
Keyword(s):  
Sorption Capacity ◽  
Electrostatic Interaction ◽  
Chemical Stability ◽  
Carbon Concentration ◽  
Pyrolysis Temperature ◽  
Surface Complexation ◽  
Point Of Zero Charge ◽  
Carbon Loss ◽  
Ph Values ◽  
The Stability

Biochar was derived from MgCl2 and MgO pretreated sawdust and corn husks at 300 °C and 600 °C, respectively, to investigate the effects of exogenous minerals on the stability and sorption performance of the resulting biochar. Impregnation with Mg decreased carbon concentration, increased yield and ash concentration, and increased the pH values at the point of zero charge (pHPZC) of the resulting biochar. The chemical stability of biochar oxidized by K2CrO7 was enhanced with increasing pyrolysis temperature and decreased with the pretreatment of MgCl2 and MgO. Mg-impregnation enhanced carbon loss of the resulting biochar and increased the sorption capacity of biochar for CR significantly, which is potentially caused by electrostatic interaction and surface complexation. This study indicates that magnesium-impregnation significantly enhances the sorption performance of anionic contaminants and the pyrolysis temperature has a greater effect on the stability of the resulting biochar than the magnesium-impregnation.

On the Robustness of Solution Strategy Classifications

2010 ◽  
Vol 31 (2) ◽  
pp. 68-73 ◽  
Author(s):  
María José Contreras ◽  
Víctor J. Rubio ◽  
Daniel Peña ◽  
José Santacreu
Keyword(s):  
Individual Differences ◽  
Study Strategies ◽  
Solution Strategy ◽  
Specific Test ◽  
Spatial Tasks ◽  
The Stability ◽  
Strategy Changes ◽  
Over Time

Individual differences in performance when solving spatial tasks can be partly explained by differences in the strategies used. Two main difficulties arise when studying such strategies: the identification of the strategy itself and the stability of the strategy over time. In the present study strategies were separated into three categories: segmented (analytic), holistic-feedback dependent, and holistic-planned, according to the procedure described by Peña, Contreras, Shih, and Santacreu (2008) . A group of individuals were evaluated twice on a 1-year test-retest basis. During the 1-year interval between tests, the participants were not able to prepare for the specific test used in this study or similar ones. It was found that 60% of the individuals kept the same strategy throughout the tests. When strategy changes did occur, they were usually due to a better strategy. These results prove the robustness of using strategy-based procedures for studying individual differences in spatial tasks.

On the Stability of Evaluative Conditioning Effects

2013 ◽  
Vol 44 (6) ◽  
pp. 380-389 ◽  
Author(s):  
Sabine Förderer ◽  
Christian Unkelbach
Keyword(s):  
Evaluative Conditioning ◽  
Indirect Measures ◽  
The Stability ◽  
Over Time

Evaluative conditioning (EC) refers to valence changes in neutral stimuli (CSs) through repeated pairing with liked or disliked stimuli (USs). The present study examined the stability of EC effects in the course of 1 week. We investigated how this stability depends on memory for US valence and US identity. We also investigated whether CSs evaluations occurring immediately after conditioning (i.e., evaluative consolidation) are necessary for stable EC effects. Participants showed stable EC effects on direct and indirect measures, independent of evaluations immediately after conditioning. EC effects depended on memory for US valence but not for US identity. And although memory decreased significantly over time, EC effects remained stable. These data suggest that evaluative consolidation is not necessary, and that conditioned preferences and attitudes might persist even when people do not remember the concrete source anymore.

Sign in / Sign up

Export Citation Format

Share Document