The influence of organic matter extracted from humified clover on the properties of amorphous aluminosilicates. I. Surface charge

Soil Research ◽  
1978 ◽  
Vol 16 (3) ◽  
pp. 327 ◽  
Author(s):  
KW Perrott
Keyword(s):  
Surface Charge ◽  
Negative Charge ◽  
Positive Charge ◽  
Degree Of Polymerization ◽  
Aqueous Extracts ◽  
Hydrous Oxides ◽  
Soil Clays ◽  
Charge Balancing ◽  
Inorganic Components ◽  
Allophanic Soil

A series of synthetic amorphous aluminosilicates, hydrous oxides and allophanic soil clays were treated with aqueous extracts of humified clover. The resulting changes in surface charge due to organic treatment were determined by comparing the charge characteristics of these organic treated samples and samples treated with a synthetic mixture of the inorganic components of the humified clover extract. Organic treatment caused a change of net surface charge to more negative values. The change in surface charge varied with the mole ratio Al/(Al+Si) of the aluminosilicate, being largest at low values of Al/(Al+Si). Where the aluminosilicates contain positive charges these are reduced by the organic treatment. This is a major contributor to the alteration of net surface charge in the more aluminous samples. The effect of organic treatment on the charge characteristics of allophanic soil clays was similar to that for the synthetic aluminosilicates of intermediate composition. The inorganic treatments also caused an increase in negative charge, and this is attributed to the neutralization of positive charge by the adsorption of phosphate and the removal of charge-balancing aluminium-hydroxy material. The effect of the organic and inorganic treatments on the positive and negative charge components of amorphous aluminosilicates is discussed in terms of the degree of polymerization of chargebalancing hydroxy-aluminium as envisaged in current models of the structure of amorphous aluminosilicates.

Using variable charge characteristics to understand the exchangeable cation status of oxic soils

Soil Research ◽  
1984 ◽  
Vol 22 (1) ◽  
pp. 71 ◽  
Author(s):  
GP Gillman
Keyword(s):  
Surface Charge ◽  
Soil Ph ◽  
Negative Charge ◽  
Positive Charge ◽  
Exchangeable Cations ◽  
Point Of Zero Charge ◽  
Exchangeable Cation ◽  
Charge Measurement ◽  
Variable Charge ◽  
Variable Surface

The model of Uehara and Gillman was used to estimate the amounts of permanent surface charge, and variable surface charge at soil pH, in two soils from the high rainfall region of coastal Queensland. For each soil series, samples from virgin rain-forest were compared with soil collected from nearby sugarcane fields. One soil contained relatively large amounts of permanent negative charge (up to 3 m.e. per 100g), and hence was moderately supplied with exchangeable cations, while the other soil was dominated by variable charge components and at soil pH contained sufficient positive charge to reduce exchangeable cations to near zero values, despite the presence of about 1 m.e. per 100 g of permanent negative charge. In the latter the position of soil pH with respect to the point of zero charge is of utmost importance for the development of cation exchange capacity. The effect of adsorbed sulfate on positive charge measurement, and valency of the ion used for negative charge measurement, are briefly discussed.

Clay mineralogy and surface charge characteristics of basaltic soils from Western Samoa

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 545-556 ◽  
Author(s):  
R. Naidu ◽  
R. J. Morrison ◽  
L. Janik ◽  
M. Asghar
Keyword(s):  
Surface Charge ◽  
Potential Model ◽  
Negative Charge ◽  
Positive Charge ◽  
Clay Mineralogy ◽  
Ph Values ◽  
Western Samoa ◽  
Infrared Studies ◽  
Constant Potential ◽  
Basaltic Soils

AbstractThe clay mineralogy and surface charge characteristics of four basaltic soils from Western Samoa have been studied. The soils contained subordinate to dominant amounts of poorly ordered allophanic material in addition to varying amounts of crystalline free iron oxide minerals. Infrared studies revealed the presence of trace to subordinate amounts of kaolin minerals in all the soils. The surface charge-pH curves followed a constant potential model indicating the presence of substantial amounts of pH-dependent charge. Some negative charge was present, however, at pH values as low as 3.0 and small quantities of positive charge were detected at pH values as high as 9. Values for PZC ranged from 2.2 to 3.9 and these were generally higher than the pHo determined by the ΔpH method.

Surface charge in some New Zealand soils measured at typical ionic strength

Soil Research ◽  
1992 ◽  
Vol 30 (3) ◽  
pp. 331 ◽  
Author(s):  
RL Parfitt
Keyword(s):  
New Zealand ◽  
Ionic Strength ◽  
Negative Charge ◽  
Positive Charge ◽  
Appreciable Amount ◽  
Surface Charges ◽  
Ph Values ◽  
Soil Solutions ◽  
Negative Surface ◽  
Allophanic Soil

The positive and negative surface charges of some New Zealand soils used for horticulture were measured at different pH values using 0.002 M CaCl2 solutions, Which have a similar ionic strength to soil solutions in New Zealand. The surface negative charge increased with pH for all soil samples including those containing mica and smectite. This behaviour was mainly due to the presence of organic matter and allophane both of which had an appreciable amount of variable negative charge. Allophanic soil B horizons had a higher positive charge than that of the Oxidic soils, which was less than 1 cmol kg-1 at pH 5.

The influence of organic matter extracted from humified clover on the properties of amorphous aluminosilicates.II. Phosphate retention

Soil Research ◽  
1978 ◽  
Vol 16 (3) ◽  
pp. 341 ◽  
Author(s):  
KW Perrott
Keyword(s):  
Organic Matter ◽  
Degree Of Polymerization ◽  
Water Soluble ◽  
Soluble Organic Matter ◽  
Retention Capacity ◽  
Phosphate Retention ◽  
Soil Clay ◽  
Charge Balancing ◽  
Allophanic Soil ◽  
Organomineral Complexes

Freshly formed water soluble organic matter extracted from humified clover leaves was used to treat a range of amorphous aluminosilicates and hydrous alumina. Phosphate retention isotherms were determined on the resulting organomineral complexes. These isotherms revealed the influence of the organic matter on phosphate retention by amorphous aluminosilicates. The organic treatment was found to reduce phosphate retention by hydrous alumina and amorphous synthetic aluminosilicates with high and low Al/(Al+Si) mole ratios. There was no depression of phosphate retention with amorphous aluminosilicates of intermediate composition. Similarly, the phosphate retention capacity of an allophanic soil clay of intermediate Al/(Al+Si) mole ratio was not reduced by organic treatment. These results appear to be related to the degree of polymerization of charge balancing hydroxy-aluminium in the aluminosilicates.

Changes in the surface charge of bacteria caused by heavy metals do not affect survival

1996 ◽  
Vol 42 (7) ◽  
pp. 621-627 ◽  
Author(s):  
Y. E. Collins ◽  
G. Stotzky
Keyword(s):  
Heavy Metals ◽  
Surface Charge ◽  
Negative Charge ◽  
Positive Charge ◽  
Agrobacterium Radiobacter ◽  
Charge Reversal ◽  
Ph Values ◽  
A Charge ◽  
Net Positive Charge ◽  
Cu And Zn

Bacillus subtilis and Agrobacterium radiobacter remained viable when exposed to Ni (1 × 10−4 M; ionic strength (μ) = 3 × 10−4) at pH values known to cause a change of the net negative charge of the cells to a net positive charge (charge reversal). The gross morphology, as determined by scanning electron microscopy, of these and other bacteria and of Saccharomyces cerevisiae was not altered in the presence of Ni, Cu, and Zn (1 × 10−4 M; μ = 3 × 10−4), which caused a charge reversal at pH values between 6.0 and 9.0. Similar results were obtained in the presence of Na and Mg, which did not cause charge reversal at the same μ and pH values. These results confirmed that cells remain viable when their surface charge is changed in the presence of some heavy metals at high pH values.Key words: heavy metals, electrokinetic properties, survival of bacteria.

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 Effect of Hyperglycemia on the Total Surface Charge of the Erythrocyte Membrane in Patients with Metabolic Syndrome

2019 ◽  
Vol 15 (3) ◽  
pp. 322-327
Author(s):  
V. I. Podzolkov ◽  
T. V. Koroleva ◽  
M. G. Kudryavtseva
Keyword(s):  
Metabolic Syndrome ◽  
Surface Charge ◽  
Erythrocyte Membrane ◽  
Negative Charge ◽  
Fasting Blood Glucose ◽  
Microvascular Blood Flow ◽  
Erythrocyte Membranes ◽  
Vascular Changes ◽  
Group 2 ◽  
Group 1

Aim. To study the effect of hyperglycemia on the total surface charge of the erythrocyte membrane (SCEM) in patients with metabolic syndrome (MS).Material and methods. 112 MS patients were examined (45 men and 67 women) (mean age 61.4±7.2 years, average MS duration 8.7±5.2 years). The level of SCEM was determined by adsorption of a positive cationic dye (cationic blue O) on the surface of the plasma membrane of erythrocytes to completely neutralize their negative charge, followed by photometry of the solution and calculation of the number of charges on the cell surface of erythrocytes.Results. In the main group of patients with MS, abdominal obesity was observed in 100% of patients, arterial hypertension – in 73%, hyperglycemia – in 75%, dyslipidemia – in 80%. The level of glycated hemoglobin (HbA1c) was determined in all patients with MS, which was 7.3±1.9%. Patients with MS were conditionally divided according to the level of HbA1c into 2 groups (group 1 – HbA1c from 6.6 to 7.8%, group 2 – more than 7.8%). In MS patients with hyperglycemia, the SCEM values were significantly lower than in the group of patients without hyperglycemia (1.58±0.05×107 and 1.64±0.03×107, respectively; p=0.001)., Significant negative correlations between SCEM and the fasting blood glucose level, hyperglycemia duration, HbA1c level were found in patients with MS.Conclusion. SCEM indices reliably depended on the presence, severity and duration of hyperglycemia, which indicated the effect of impaired carbohydrate metabolism on the state of electric charge of erythrocyte membranes and, therefore, on the mechanisms of microvascular blood flow, thereby contributing to the development of vascular changes in patients with MS.

scholarly journals Indication of the Coronavirus Model Using a Nanowire Biosensor

Proceedings ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 50
Author(s):  
Vladimir Generalov ◽  
Olga Naumova ◽  
Dmitry Shcherbakov ◽  
Alexander Safatov ◽  
Boris Zaitsev ◽  
...  
Keyword(s):  
Field Effect ◽  
Field Effect Transistor ◽  
Negative Charge ◽  
Positive Charge ◽  
Silicon On Insulator ◽  
Nanowire Surface ◽  
Before And After ◽  
Effect Transistor ◽  
Current Value ◽  
Silicon On Insulator Technology

The presented results indicate virus-like particles of the coronavirus (CVP) using a nanowire (NW) biosensor based on silicon-on-insulator technology. In the experiment, we used suspensions of CVP and of specific antibodies to the virus. Measurements of the current value of the field-effect transistor before and after the introduction of the CVP on the surface of the nanowire were performed. Results showed antibody + CVP complexes on the phase section with the surface of the nanowire modulate the current of the field-effect transistor; CVP has an electrically positive charge on the phase section “nanowire surface-viral suspension»; antibody + CVP complexes have an electrically negative charge on the phase section “nanowire surface-viral suspension”; the sensitivity of the biosensor is made up of 10−18 M; the time display was 200–300 s.

Surface charge on kaolinites in aqueous suspension

Soil Research ◽  
1976 ◽  
Vol 14 (2) ◽  
pp. 197 ◽  
Author(s):  
MDA Bolland ◽  
AM Posner ◽  
JP Quirk
Keyword(s):  
Surface Charge ◽  
Positive Charge ◽  
Aqueous Suspension ◽  
Isomorphous Substitution ◽  
Ph Values ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Decreasing Ph ◽  
Ph Range ◽  
Exchange Technique

The surface charge of several natural kaolinites was measured in the pH range 3-10 using an exchange technique. The positive charge was found to increase with decreasing pH and sometimes to increase with increasing ionic strength; it occurred on the kaolinites at pH values as high as 9 and 10 and was particularly evident at high ionic strengths. The positive surface charge on kaolinites is thought to be due to exposed alumina such as is found on oxide surfaces. Aluminium was found to dissolve from kaolinite at pH values beiow about 6.5. Aluminium dissolution increased with decreasing pH and time. When the proportion of dissolved aluminium ions balancing negative surface charge was taken into account, the negative and net negative surface charge on kaolinite was concluded to be largely due to pH independent charge resulting from isomorphous substitution, together with some pH dependent charge due to exposed SiOH sites. If Na+ was the index cation, dissolved aluminium ions from the clay replaced some of the Na+ balancing the negative surface charge. However, when Cs+ was the index cation, less Cs+ balancing the negative surface charge on the clay was replaced by dissolved aluminium. As the concentration of either Na+ or Cs+ was increased, less dissolved aluminium replaced the index cation as a counteraction to the negative surface charge.

scholarly journals The mechanism of spray electrification: the waterfall effect

2016 ◽  
Author(s):  
James K. Beattie
Keyword(s):  
Negative Charge ◽  
Positive Charge ◽  
Hydrophobic Hydration ◽  
General Phenomenon ◽  
Aqueous Interfaces ◽  
Preferential Adsorption ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Low Permittivity ◽  
Net Positive Charge

Abstract. The waterfall effect describes the separation of charge by splashing at the base of a waterfall. Smaller drops that have a net negative charge are created, while larger drops and/or the bulk maintain overall charge neutrality with a net positive charge. Since it was first described by Lenard (1892) the effect has been confirmed many times, but a molecular explanation has not been available. Application of our fluctuation-correlation model of hydrophobic hydration accounts for the negative charge observed at aqueous interfaces with low permittivity materials. The negative surface charge observed in the waterfall effect is created by the preferential adsorption of hydroxide ions generated from the autolysis of water. On splashing, shear forces generate small negative drops from the surface, leaving a positive charge on the remaining large fragment. The waterfall effect is a manifestation of the general phenomenon of the negative charge at the interface between water and hydrophobic surfaces that is created by the preferential adsorption of hydroxide ions.

Sign in / Sign up

Export Citation Format

Share Document