Complexation, Stability and Behavior of L-Cysteine and L-Lysine with Different Iron Sources

1984 ◽  
Vol 47 (1) ◽  
pp. 36-40 ◽  
Author(s):  
S. M. FLYNN ◽  
F. M. CLYDESDALE ◽  
O. T. ZAJICEK
Keyword(s):  
Ferric Chloride ◽  
Ferrous Sulfate ◽  
Mixed Valence ◽  
Qualitative Evaluation ◽  
Low Ph ◽  
Iron Hydroxides ◽  
The Stability ◽  
Ph Range ◽  
Effective Stability ◽  
And Behavior

Effective stability constants for cysteine and lysine with five different iron sources were evaluated along with their behavior in solution. The values obtained for ferric chloride-cysteine, ferrous sulfate-cysteine, ferric chloride-lysine, ferrous sulfate-lysine, hydrogen-reduced lysine, and electrolytic-reduced lysine were 6.81 × 102 to 2.78 × 103, 1.33 × 105 to 1.36 × 105, 6.00 × 10−4 to 7.64 × 10−3, 6.37 ×10−4 to 4.82× 10−3, 9.34 × 10−2 to 1.38 × 10−1, and 4.18 × 10−4 to 7.27 × 10−4, respectively. No measurable complexation occurred with hydrogen- and electrolytic-reduced iron with cysteine nor with ferric orthophosphate and cysteine or lysine. The stability of soluble ferric cysteine over the pH range 2.0 to 7.4 indicates that this complex has the potential to be used as an iron additive in food. Approximately half of the hydrogen and electrolytic reduced iron and only 0.11% of ferric orthophosphate were soluble in acid, whereas ferric chloride and ferrous sulfate were completely soluble. Qualitative evaluation of the iron-amino acid systems over a range of pH from 2.0 to 12.0 indicated that there was a mixed valence state of free iron in most cases with low pH favoring reduction and high pH oxidation, until precipitation of iron hydroxides occurred.

scholarly journals Common Loon, Gavia immer, Breeding Success in Relation to Lake pH and Lake Size Over 25 Years

2009 ◽  
Vol 123 (2) ◽  
pp. 146 ◽  
Author(s):  
Robert Alvo
Keyword(s):  
Breeding Success ◽  
Low Ph ◽  
Single Pair ◽  
Gavia Immer ◽  
Common Loon ◽  
Sulphur Deposition ◽  
Acidic Lakes ◽  
Ph Range ◽  
Lake Size ◽  
Critical Ph

I monitored Common Loon (Gavia immer) breeding success in relation to lake pH (range 4.0–8.5) between 1982 and 2007 on 38 single-pair lakes (5–88 ha) in the Sudbury, Ontario, area. No chicks fledged on lakes with pH < 4.4. Chicks fledged on lakes with slightly higher pH only if the lakes were relatively large. Acidic lakes became less acidic as sulphur dioxide emissions from the Sudbury smelters and sulphur deposition from other long-range sources decreased. Two lakes initially too acidic to support successful loon reproduction eventually had successful reproduction. One loon pair used two large acidic lakes (combined area 140 ha) connected by shallow rapids, and one of the adults made extremely long dives (average = 99 s) while foraging for the chicks. One chick died on that lake after apparently ingesting a very large food item; the lack of smaller items was attributed to the lake’s acidity. My results suggest that a shortage of food for chicks is the main reason why low pH reduces breeding success. I suggest that, for lakes without high levels of dissolved organic carbon (DOC), the critical pH for loon breeding success is approximately 4.3, and the suboptimal pH is approximately 4.4–6.0.

scholarly journals Carrier-microencapsulation using Al-catecholate complex to suppress arsenopyrite oxidation: Evaluation of the coating stability under simulated weathering conditions

2019 ◽  
Vol 268 ◽  
pp. 06002 ◽  
Author(s):  
Kensuke Seno ◽  
Ilhwan Park ◽  
Carlito Tabelin ◽  
Kagehiro Magaribuchi ◽  
Mayumi Ito ◽  
...  
Keyword(s):  
Protective Coating ◽  
Sulfide Mineral ◽  
Sulfide Minerals ◽  
Low Ph ◽  
Oxidation Products ◽  
Arsenic Sulfide ◽  
Catecholate Complex ◽  
Coating Stability ◽  
The Stability

Arsenopyrite (FeAsS) is the most common primary arsenic-sulfide mineral in nature, and its oxidation causes the release of toxic arsenic (As). To mitigate these problems, carrier-microencapsulation (CME), a technique that passivates sulfide minerals by covering their surfaces with a protective coating, has been developed. In the previous study of authors on CME, Al-catecholate complex significantly suppressed arsenopyrite oxidation via electron donating effects of the complex and the formation of an Al-oxyhydroxide coating. For the application of this technique to real tailings, however, further study should be carried out to elucidate long-term effectiveness of the coating to suppress arsenopyrite oxidation. This study investigates the stability of the coating formed on arsenopyrite by Al-based CME using weathering tests. The Al-oxyhydroxide coating suppressed arsenopyrite oxidation until about 50 days of the experiment, but after this, the amounts of oxidation products like dissolved S and As increased due to the gradual dissolution of the coating with time as a result of the low pH of leachate. This suggests that co-disposal of Al-based CME-treated arsenopyrite with minerals that have appropriate neutralization potentials, so that the pH is maintained at around 5 to 8 where Al-oxyhydroxide is stable.

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

scholarly journals Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Dariusz Wyrzykowski ◽  
Joanna Pranczk ◽  
Dagmara Jacewicz ◽  
Aleksandra Tesmar ◽  
Bogusław Pilarski ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Substitution Reactions ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Hydroxo Complexes ◽  
Binary Complexes ◽  
Vis Spectroscopy ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Ph Range

AbstractA potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.

scholarly journals An Investigation into the Adsorption of Aniline from Aqueous Solution Using H-Beta Zeolites and Copper-Exchanged Beta Zeolites

2005 ◽  
Vol 23 (3) ◽  
pp. 255-266 ◽  
Author(s):  
J. O'Brien ◽  
T. Curtin ◽  
T.F. O'Dwyer
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Zeolite Beta ◽  
Langmuir Model ◽  
Beta Zeolite ◽  
Copper Leaching ◽  
Beta Zeolites ◽  
The Stability ◽  
Ph Range ◽  
Adsorbent Materials

Zeolite beta, a large-pore zeolite, was investigated in this study with a view to examining it as a potential adsorbent for the removal of aniline from aqueous solutions. Two different metal-loaded zeolites were prepared by exchanging H-beta zeolite (SiO2/Al2O3 = 75:1) with copper. The influence of exchanged copper on the uptake level was assessed. The effect of varying the silica-to-alumina ratio of the H-beta zeolite on the aniline uptake level was also examined, using three different H-beta zeolites with ratios of 25:1, 75:1 and 150:1 as adsorbents. The sorption experiments indicated an uptake level of ca. 110–120 mg/g for each zeolite and this level was also adsorbed by the copper-modified H-beta zeolites (SiO2/Al2O3 = 75:1). In all cases, the adsorption process followed the Langmuir model for adsorption and the level of aniline adsorbed was largely unaffected by a change in temperature or the presence of extra framework copper. The stability of the exchanged copper on these zeolites was then examined by measuring the quantity of copper leached from each zeolite into solution as a function of pH. Minimum copper leaching was observed in the pH range 5–11. This provided a stable pH working range for the adsorbent materials.

Formulation and Stability Test of Lip Cream Preparation of Kenop Flower Ethanol Extract (Gomphrena globosa L.)

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Mevi Irianti Tonapa ◽  
Rani Dewi Pratiwi ◽  
Elsye Gunawan
Keyword(s):  
Ph Value ◽  
Ethanol Extract ◽  
Stability Test ◽  
Gomphrena Globosa ◽  
Homogeneous Composition ◽  
Semi Solid ◽  
The Stability ◽  
Ph Range ◽  
Average Dispersion ◽  
Brown Color

Kenop Flower (Gomphrena globosa L.) is used in the manufacture of lip cream because contains betacyanin pigments that function as color pigments. This study aims to determine the physical quality and stability of the lip cream preparation of the ethanol extract of kenop flower (Gomphrena globosa L.). This research was conducted experimentally, including the manufacture of lip cream formulations with ethanol extract of kenop flower (Gomphrena globosa L.) with a concentration of 10%. The results of the physical examination test for lip cream preparations for all preparations have a distinctive vanilla aroma with a semi-solid texture, F0 has ivory white color and F1-F3 has a brown color. The preparations had a homogeneous composition, average pH 6-7, had good greasing power, 5.0-5.8 average dispersion and 60.33-66.67 seconds average adhesion. The stability test carried out on day 28 found that all preparations were stable, had a distinctive vanilla aroma with a semi-solid texture, F0 had ivory white color and F1-F3 had a brown color. The preparation has a homogeneous composition; the average pH is 6-7. Where the lip cream formulas F1 and F3 decreased the pH value on the 28th day from 7 to 6 but tended to be stable and in the pH range that matched the lip pH. And there is no phase separation in all formulas.

Physicochemical investigation on thiomalate complexes of nickel

1968 ◽  
Vol 21 (3) ◽  
pp. 641 ◽  
Author(s):  
RS Saxena ◽  
KC Gupta ◽  
ML Mittal
Keyword(s):  
Aqueous Medium ◽  
Stability Constants ◽  
Alternative Methods ◽  
Acid System ◽  
Kcal Mole ◽  
Physicochemical Investigation ◽  
Different Temperatures ◽  
The Stability ◽  
Ph Range ◽  
Deep Violet

Potentiometric and conductometric studies of the nickel-thiomalic acid system, in aqueous medium of 0. lM KNO3, reveal the formation of two complexes; one light violet 1 : 1 predominating at pH 6.5-7.5 and another deep violet 1 : 2 in the pH range 8.5-10.0. The stability constants of the complexes formed have been determined by applying Calvin and Melchior's extension of Bjerrum's method at three different temperatures and were further refined by using alternative methods. The logK values (final) for 1 : 1 and 1 : 2 complexes at 20, 25, and 30� have been found to be 7.86, 7.87, 7.96, and 6.24, 6.31, 6.39 respectively. The values of the overall changes in ΔG, ΔH, and ΔS accompanying the reaction have also been evaluated at 25� and found to be -19.31 kcal/mole, -8.77 kcal/mole, and +35.36 cal/deg respectively.

The stability of onoratoite, Sb8O11Cl2, in the supergene environment

2014 ◽  
Vol 78 (7) ◽  
pp. 1671-1675 ◽  
Author(s):  
Adam J. Roper ◽  
Peter Leverett ◽  
Timothy D. Murphy ◽  
Peter A. Williams
Keyword(s):  
Significant Influence ◽  
Secondary Phase ◽  
Low Ph ◽  
Stable Phase ◽  
Supergene Zone ◽  
A Value ◽  
Solubility Studies ◽  
The Stability ◽  
Very High

AbstractSynthesis and solubility studies of onoratoite have been undertaken to determine the role of this rare secondary phase in the immobilization of Sb and the conditions responsible for its formation in the supergene zone. Solubility studies were undertaken at 298.15 K. A value of ΔGfθ (Sb8O11Cl2, s, 298.15 K) = –2576 ±12 kJ mol–1 was derived. Calculations involving sénarmontite, Sb2O3, klebelsbergite, Sb4O4SO4(OH)2 and schafarzikite, FeSb2O4, show that onoratoite is a thermodynamically stable phase only at negligible activities of SO42–(aq) and low activities of Fe2+(aq), at low pH and very high activities of Cl–(aq). This explains why onoratoite is such a rare secondary phase and why it cannot exert any significant influence on the dispersion of Sb in the supergene environment.

scholarly journals THE ABSORPTION SPECTRUM OF VISUAL PURPLE

1938 ◽  
Vol 21 (4) ◽  
pp. 411-430 ◽  
Author(s):  
Aurin M. Chase ◽  
Charles Haig
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Light Transmission ◽  
Low Ph ◽  
The Other ◽  
Distilled Water ◽  
Color Purity ◽  
Chemical Combination ◽  
Ph Range ◽  
Sensitive Group

The absorption spectra of visual purple solutions extracted by various means were measured with a sensitive photoelectric spectrophotometer and compared with the classical visual purple absorption spectrum. Hardening the retinas in alum before extraction yielded visual purple solutions of much higher light transmission in the blue and violet, probably because of the removal of light-dispersing substances. Re-extraction indicated that visual purple is more soluble in the extractive than are the other colored retinal components. However, the concentration of the extractive did not affect the color purity of the extraction but did influence the keeping power. This suggests a chemical combination between the extractive and visual purple. The pH of the extractive affected the color purity of the resulting solution. Over the pH range from 5.5 to 10.0, the visual purple color purity was greatest at the low pH. Temperature during extraction was also effective, the color purity being greater the higher the temperature, up to 40°C. Drying and subsequent re-dissolving of visual purple solutions extracted with digitalin freed the solution of some protein impurities and increased its keeping power. Dialysis against distilled water seemed to precipitate visual purple from solution irreversibly. None of the treatments described improved the symmetry of the unbleached visual purple absorption spectrum sufficiently for it to resemble the classical absorption spectrum. Therefore it is very likely that the classical absorption spectrum is that of the light-sensitive group only and that the absorption spectra of our purest unbleached visual purple solutions represent the molecule as a whole.

scholarly journals Bacillus cereus NVH 0500/00 Can Adhere to Mucin but Cannot Produce Enterotoxins during Gastrointestinal Simulation

2015 ◽  
Vol 82 (1) ◽  
pp. 289-296 ◽  
Author(s):  
Varvara Tsilia ◽  
Frederiek-Maarten Kerckhof ◽  
Andreja Rajkovic ◽  
Marc Heyndrickx ◽  
Tom Van de Wiele
Keyword(s):  
Bacillus Cereus ◽  
Food Poisoning ◽  
Intestinal Bacteria ◽  
Low Ph ◽  
Final Concentration ◽  
Adhesion Assay ◽  
Content Type ◽  
The Stability ◽  
Bacterial Concentrations

ABSTRACTAdhesion to the intestinal epithelium could constitute an essential mechanism ofBacillus cereuspathogenesis. However, the enterocytes are protected by mucus, a secretion composed mainly of mucin glycoproteins. These may serve as nutrients and sites of adhesion for intestinal bacteria. In this study, the food poisoning bacteriumB. cereusNVH 0500/00 was exposedin vitroto gastrointestinal hurdles prior to evaluation of its attachment to mucin microcosms and its ability to produce nonhemolytic enterotoxin (Nhe). The persistence of mucin-adherentB. cereusafter simulated gut emptying was determined using a mucin adhesion assay. The stability of Nhe toward bile and pancreatin (intestinal components) in the presence of mucin agar was also investigated.B. cereuscould grow and simultaneously adhere to mucin duringin vitroileal incubation, despite the adverse effect of prior exposure to a low pH or intestinal components. The final concentration ofB. cereusin the simulated lumen at 8 h of incubation was 6.62 ± 0.87 log CFU ml−1. At that point, the percentage of adhesion was approximately 6%. No enterotoxin was detected in the ileum, due to either insufficient bacterial concentrations or Nhe degradation. Nevertheless, mucin appears to retainB. cereusand to supply it to the small intestine after simulated gut emptying. Additionally, mucin may play a role in the protection of enterotoxins from degradation by intestinal components.

Sign in / Sign up

Export Citation Format

Share Document