Changes in charge charactistics of soils after treatment with 0.5M calcium chloride at pH 1.5

Soil Research ◽  
1967 ◽  
Vol 5 (2) ◽  
pp. 247 ◽  
Author(s):  
CK Tweneboah ◽  
DJ Greenland ◽  
JM Oades
Keyword(s):  
Clay Minerals ◽  
Calcium Chloride ◽  
Negative Charge ◽  
Positive Charge ◽  
Low Ph ◽  
Rapid Rate ◽  
Constant Rate ◽  
Ph Range ◽  
Kinetics Of

The kinetics of the removal of iron, aluminium, and silicon from soils and clays in the pH range 0-3 have been studied using a number of oxides, clay minerals, and soils. At pH 1.5, aluminium is removed but little iron or silicon. An initial rapid rate of aluminium extraction is followed by a slower constant rate. The rapidly released aluminium is extracted in approximately 12 hr using 0.5M CaCl2 at pH 1.5.reatment of a range of soils and clays by this method reduced the positive charge developed at low pH very substantially but had little effect on the negative charge. It is suggested that the positive charges in the soils studied are mostly due to the 'active' aluminium oxides.

scholarly journals A marked gradation in active-centre properties in the cysteine proteinases revealed by neutral and anionic reactivity probes. Reactivity characteristics of the thiol groups of actinidin, ficin, papain and papaya peptidase A towards 4,4′-dipyridyl disulphide and 5,5′-dithiobis-(2-nitrobenzoate) dianion

1983 ◽  
Vol 209 (3) ◽  
pp. 873-879 ◽  
Author(s):  
K Brocklehurst ◽  
S M Mushiri ◽  
G Patel ◽  
F Willenbrock
Keyword(s):  
Negative Charge ◽  
Cysteine Proteinase ◽  
Catalytic Site ◽  
Side Chain ◽  
Cysteine Proteinases ◽  
Thiol Groups ◽  
Active Centre ◽  
Ph Range ◽  
Thiolate Anions ◽  
Kinetics Of

1. The kinetics of the reactions of the catalytic-site thiol groups of actinidin (the cysteine proteinase from Actinidia chinensis), ficin (EC 3.4.22.3), papain (EC 3.4.22.2) and papaya peptidase A (the other monothiol cysteine proteinase component of Carica papaya) with 4,4′-dipyridyl disulphide (4-Py-S-S-4-Py) and with 5,5′-dithiobis-(2-nitrobenzoate) dianion (Nbs22-) were studied in the pH range approx. 6-10. These studies provided the pH-independent second-order rate constants (k) for the reactions of the two probe reagents with the catalytic-site thiolate anions each in the environment of a neutral histidine side chain where an active-centre carboxy group would be ionized. 2. The ratio R equal to kNbs22-/k4-Py-S-S-4-Py provides an index of the catalytic-site solvation properties of the four cysteine proteinases and varies markedly from one enzyme to another, being 0.80 for papaya peptidase A (0.86 for the model thiol, 2-mercaptoethanol), 29 for actinidin, 0.18 for ficin and 0.015 for papain. These differences appear to derive mainly from the response of the enzyme to the negative charge on Nbs22-. 3. Possible implications of these results for (a) mechanisms of cysteine proteinase catalysis and (b) the possibility of using series of functionally related enzymes in the study of mechanism are discussed.

Investigation of the Range of a Plastic pH Sensor Based on a Dibasic Ionophore

1992 ◽  
Vol 45 (2) ◽  
pp. 435 ◽  
Author(s):  
TJ Cardwell ◽  
RW Cattrall ◽  
LW Deady ◽  
KA Murphy
Keyword(s):  
Positive Charge ◽  
Ph Sensor ◽  
Low Ph ◽  
Membrane Electrode ◽  
Neutral Carrier ◽  
Ph Values ◽  
Response Range ◽  
Ph Scale ◽  
Ph Range ◽  
Sensitive Membrane

A study is reported of the use of a neutral carrier reagent containing two nitrogen atoms with very different basicities in a pH-sensitive membrane electrode with a view to obtaining a broad response range. This electrode responds well in the pH region of 6-12 but suffers anion interference in the region of pH 2-6. A study is included of the effect of adding various amounts of potassium tetrakis(4-chloropheny1)borate as an anion suppressing reagent to the membrane in order to reduce the anion interference at low pH values. The conclusion is drawn that an extension to the working pH range is not possible with this approach unless controlled amounts of anion suppressing reagent can be provided to approximately balance the positive charge of the carrier in each region of the pH scale.

ELECTROPHILIC DISPLACEMENT REACTIONS: XV. KINETICS AND MECHANISM OF THE BASE-CATALYZED PROTODEBORONATION OF ARENEBORONIC ACIDS

1963 ◽  
Vol 41 (12) ◽  
pp. 3081-3090 ◽  
Author(s):  
Henry G. Kuivila ◽  
Joseph F. Reuwer Jr. ◽  
John A. Mangravite
Keyword(s):  
Acid Catalysis ◽  
Low Ph ◽  
Ion Concentration ◽  
Buffer Concentration ◽  
Hammett Equation ◽  
Hydroxide Ion ◽  
Displacement Reactions ◽  
Acid Catalyzed ◽  
Ph Range ◽  
Kinetics Of

An investigation of the kinetics of the protodeboronation of benzeneboronic acid in water in the pH range 2.0 to 6.7 is described. In addition to the acid-catalyzed reaction studied earlier a reaction whose rate is independent of pH and one whose rate increases linearly with hydroxide ion concentration have been observed. The effect of malonate buffer concentration at low pH confirms the earlier observations of general acid catalysis. Changes in buffer concentration at pH 6.70 have no effect on rate indicating specific hydroxide ion catalysis. Effect of substituents in the ortho, meta, and para position of the benzene ring on the rate of protodeboronation have been examined. Ortho–para ratios for this reaction are high; possible reasons for this are discussed. The Hammett equation using σ correlates the rates for meta and para substituents.

Study on Calcium Ions Affecting Mechanism to Collecting Quartz in the System of Dodecyl Sulphonate

2012 ◽  
Vol 581-582 ◽  
pp. 983-987
Author(s):  
Lin Zhang Chen ◽  
Qing Lin Hou ◽  
Rui Ming Yin ◽  
Li Jing ◽  
Fu Bao Ji
Keyword(s):  
Zeta Potential ◽  
Calcium Ions ◽  
Recovery Rate ◽  
Negative Charge ◽  
Positive Charge ◽  
Solution Chemistry ◽  
Quartz Surface ◽  
Solution Composition ◽  
Potential Measurement ◽  
Ph Range

This article studied on calcium ions affecting mechanism to collecting quartz in the system of dodecyl sulphate. Studied calcium ions on Zeta potential of quartz surface and flotation behavior through flotation experiment, Zeta potential measurement, infrared spectroscopy and solution chemistry of calcium calculation. The results show that the ability of collecting quartz by anionic collector dodecyl sulphate is weak within pH range of 4-14, and basically can be seen cannot collect quartz. When adding calcium ions, the capacity of collecting quartz increases significantly. By Zeta potential of quartz surface, when pH>2, Zeta potential of the quartz surface shows negative charge, is not conducive to the adsorption of the anionic collector dodecyl sulphate. When adding calcium ions, Zeta potential increases significantly, and at pH = 10, Zeta potential begin to rise sharply, at this point, the concentration of Ca(OH)+ in the solution composition of calcium is also started to increase, and the recovery rate of the quartz begin to increase sharply. The concentration of Ca(OH)+ is the maximum within pH=11.5-13.5, and Zeta potential of quartz surface shows positive charge, and the recovery rate of the quartz is corresponding to the maximum. So can be determined, Ca(OH)+ is the main reason of affecting Zeta potential of the quartz surface, and Ca(OH)+ is the main active ingredient that activate flotation of quartz in the system of anionic collector dodecyl sulphate.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

scholarly journals Zerumbone Inhibits Helicobacter pylori Urease Activity

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2663
Author(s):  
Hyun Jun Woo ◽  
Ji Yeong Yang ◽  
Pyeongjae Lee ◽  
Jong-Bae Kim ◽  
Sa-Hyun Kim
Keyword(s):  
Helicobacter Pylori ◽  
Carbon Atom ◽  
Natural Compound ◽  
Urease Activity ◽  
Negative Charge ◽  
Positive Charge ◽  
Gastric Epithelium ◽  
Functional Inhibition ◽  
Electrical Gradient ◽  
H Pylori

Helicobacter pylori (H. pylori) produces urease in order to improve its settlement and growth in the human gastric epithelium. Urease inhibitors likely represent potentially powerful therapeutics for treating H. pylori; however, their instability and toxicity have proven problematic in human clinical trials. In this study, we investigate the ability of a natural compound extracted from Zingiber zerumbet Smith, zerumbone, to inhibit the urease activity of H. pylori by formation of urease dimers, trimers, or tetramers. As an oxygen atom possesses stronger electronegativity than the first carbon atom bonded to it, in the zerumbone structure, the neighboring second carbon atom shows a relatively negative charge (δ−) and the next carbon atom shows a positive charge (δ+), sequentially. Due to this electrical gradient, it is possible that H. pylori urease with its negative charges (such as thiol radicals) might bind to the β-position carbon of zerumbone. Our results show that zerumbone dimerized, trimerized, or tetramerized with both H. pylori urease A and urease B molecules, and that this formation of complex inhibited H. pylori urease activity. Although zerumbone did not affect either gene transcription or the protein expression of urease A and urease B, our study demonstrated that zerumbone could effectively dimerize with both urease molecules and caused significant functional inhibition of urease activity. In short, our findings suggest that zerumbone may be an effective H. pylori urease inhibitor that may be suitable for therapeutic use in humans.

scholarly journals Single entity electrochemistry and the electron transfer kinetics of hydrazine oxidation

Nano Research ◽  
2021 ◽  
Author(s):  
Ruiyang Miao ◽  
Lidong Shao ◽  
Richard G. Compton
Keyword(s):  
Electron Transfer ◽  
Bulk Solution ◽  
Relative Contribution ◽  
Rate Determining Step ◽  
Multistep Process ◽  
Ph Range ◽  
Electro Catalytic Oxidation ◽  
Single Particle Impact ◽  
The Impact ◽  
Kinetics Of

AbstractThe mechanism and kinetics of the electro-catalytic oxidation of hydrazine by graphene oxide platelets randomly decorated with palladium nanoparticles are deduced using single particle impact electrochemical measurements in buffered aqueous solutions across the pH range 2–11. Both hydrazine, N2H4, and protonated hydrazine N2H5+ are shown to be electroactive following Butler-Volmer kinetics, of which the relative contribution is strongly pH-dependent. The negligible interconversion between N2H4 and N2H5+ due to the sufficiently short timescale of the impact voltammetry, allows the analysis of the two electron transfer rates from impact signals thus reflecting the composition of the bulk solution at the pH in question. In this way the rate determining step in the oxidation of each specie is deduced to be a one electron step in which no protons are released and so likely corresponds to the initial formation of a very short-lived radical cation either in solution or adsorbed on the platelet. Overall the work establishes a generic method for the elucidation of the rate determining electron transfer in a multistep process free from any complexity imposed by preceding or following chemical reactions which occur on the timescale of conventional voltammetry.

scholarly journals Kinetics of Anti-SARS-CoV-2 Antibody Responses 3 Months Post Complete Vaccination with BNT162b2; A Prospective Study in 283 Health Workers

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1942
Author(s):  
Evangelos Terpos ◽  
Ioannis P. Trougakos ◽  
Vangelis Karalis ◽  
Ioannis Ntanasis-Stathopoulos ◽  
Sentiljana Gumeni ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Health Workers ◽  
Antibody Responses ◽  
Healthy Individuals ◽  
Younger Age ◽  
Constant Rate ◽  
Rate Of Decline ◽  
A Prospective Study ◽  
Kinetics Of ◽  
Over Time

The aim of this study was to investigate the kinetics of neutralizing antibodies (NAbs) and anti-SARS-CoV-2 anti-S-RBD IgGs up to three months after the second vaccination dose with the BNT162b2 mRNA vaccine. NAbs and anti-S-RBD levels were measured on days 1 (before the first vaccine shot), 8, 22 (before the second shot), 36, 50, and three months after the second vaccination (D111) (NCT04743388). 283 health workers were included in this study. NAbs showed a rapid increase from D8 to D36 at a constant rate of about 3% per day and reached a median (SD) of 97.2% (4.7) at D36. From D36 to D50, a slight decrease in NAbs values was detected and it became more prominent between D50 and D111 when the rate of decline was determined at −0.11 per day. The median (SD) NAbs value at D111 was 92.7% (11.8). A similar pattern was also observed for anti-S-RBD antibodies. Anti-S-RBDs showed a steeper increase during D22–D36 and a lower decline rate during D36–D111. Prior COVID-19 infection and younger age were associated with superior antibody responses over time. In conclusion, we found a persistent but declining anti-SARS-CoV-2 humoral immunity at 3 months following full vaccination with BNT162b2 in healthy individuals.

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.

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