Effect Of pH Changes Research Articles

Removal of nickel from polluted water using decaying cypress leaves

Abstract Cypress leaves have been found capable of removing nickel ions from water. The maximum capacity of this removal process appears to be at ∼ pH 8.5. Several factors affecting this removal process have been studied. These include the concentration of cypress leaves, the concentration of nickel, and the presence of competing ions. The release of nickel from cypress leaves by the effect of changing pH or the addition of competing ions has been studied. Cypress leaves have been found capable of changing the pH of water. This capability has been also investigated and the effect of concentration of cypress leaves on the rate of variation of pH has been concluded.

Effect of pH changes on the killing of Staphylococcus aureus and other mastitis pathogens by bovine neutrophil granule extracts

A partly purified extract of granules from bovine neutrophils was used to investigate killing of mastitis pathogens by the non-oxidative killing system of the neutrophil. Eight strains of Staphylococcus aureus, two of Escherichia coli and two of Streptococcus uberis were used. Different strains of bacteria had different sensitivities to killing by the extract, three strains of staphylococci being particularly resistant. Whereas E coli were killed most effectively at pH 6.0, little or no killing of S aureus took place below pH 6.5 and, although S uberis were also killed better above neutral pH, significant killing also took place at acidic pH levels. Resistance to killing by the extract was not significantly correlated with that by intact neutrophils.

The actions of phenol and pentachlorophenol (PCP) on axonal conduction, ganglionic synaptic transmission, and the effect of ph changes

1. A comparison of phenol, pentachlorophenol (PCP) and procaine effects on axonal conduction were studied in vitro in the sciatic nerves of toad. PCP and procaine were respectively 6.3 and 3.15 times more potent than phenol in blocking axonal conduction. 2. Effects of PCP on synaptic transmission were studied vitro in the eighth sympathetic ganglion of toad. 3. Axonal conduction block and synaptic transmission block by phenol was reversible, but not that by PCP. 4. When the PCP ionization was increased, a lesser per cent reached the site of action, reducing its capacity to block the axonal conduction and ganglionic transmission. 5. PCP plus, 3,4-Diaminopyridine (3,4-DAP) decreased synaptic transmission block from postganglionic compound action potential (CAP) responses to supramaximal preganglionic stimulation.

Effects of pH changes on sodium pump fluxes in squid giant axon.

The effects of independently varying intracellular and extracellular pH on sodium pump fluxes were studied in the squid giant axon. By means of intracellular dialysis, we found that changes of intracellular pH (pHi), but not of extracellular pH, affected ouabain-sensitive Na+ efflux and K+ influx over the pH range of 6.0-8.6. Both fluxes were maximum at a pHi of 7.2-7.4. Variations away from this optimal pHi in either the acidic or alkaline direction resulted in a graded inhibition of both ouabain-sensitive fluxes. The kinetic basis for the inhibitory effect of acidic pHi was examined by comparing the kinetic parameters of activation of ouabain-sensitive sodium efflux by intracellular Na+ (Na+i) and extracellular K+ (K+o) at normal pHi with those at acidic pHi. We found that the inhibitory effect of intracellular acidity results from a reversible decrease in maximum velocity (Vmax), without an effect on the activation parameters for Na+i (K1/2 Na+i) or K+o (K1/2 K+o).

Ultrafiltration of protein solutions; the role of protein association in rejection and osmotic pressure

The monomer-dimer equilibrium of the protein β-lactoglobulin under neutral conditions appears to influence the rejection and the osmotic pressure build-up, both phenomena closely related to ultrafiltration. Rejection measurements indicate different rejections for the β-lactoglobulin monomers and dimers: the membrane rejects the dimer almost completely and the monomer only partially. The osmotic pressure turns out to be highly dependent on the protein concentration. A good agreement, up to high concentrations, is found between experimental data and theoretical osmotic pressures, calculated by taking into account the state of association, the excluded volume and the Donnan effects. The effect of changes in pH on the osmotic pressure has been measured: a minimum was found around pH = 4.5, where according to the literature, maximum protein-protein interaction occurs.

Effect of pH on Glycolate and Ammonia Excretion in L-MSO Treated Chlorella Cells

Abstract The effect of pH changes on the excretion of ammonia and glycolate from algal cells into the medium was investigated in L-MSO (final concentration, 0.5 mм) -treated High-and Low CO2-cells of Chlorella vulgaris 211-11 h. The excretion was analyzed in the condition in which the cells were continuously gassed with air at 25 °C. At the values tested, generally more ammonia was excreted in L-MSO-treated Low CO2-cells than in L-MSO treated High CO2-cells. In both kinds of algal cells more ammonia was excreted at low pH-values and absolutely no ammonia was excreted at pH 8. In the dark, no or only slight ammonia excretion was observed in both L-MSO-treated High and Low CO2-cells. Under all these conditions no or only very low glycolate excretion was observed in both L-MSO treated High and Low CO2-cells. In High CO2-cells rates of photosynthesis were high at pH 6 and lower at higher pH values. On the other hand Low CO2-cells showed practically little dependence of photosynthetic rates on the pH. This result might indicate that the major part of the ammonia excretion observed, was not due to the inhibition of photosynthesis at acid pH values. It is known that ammonia excretion in L-MSO treated algal cells is due to the inhibition of the refixation of ammonia which originates from the glycine-serine aminotransferase reaction in the glycolate pathway. Our results demonstrate that glycolate production and glycolate metabolism are more intense at low pH values when compared to high pH values. This is valid for both High and Low CO2-cells. Low CO2-cells in Chlorella vulgaris 211-11 h exhibit a more active glycolate metabolism than High CO2-cells.

Potential of acid activated clays in the clarification of menhaden stickwater

Abstract The primary objective of this investigation was to determine the feasibility of using acid activated clays to clarify menhaden stickwater effluent. Experiments, such as physical and chemical properties determinations, effect of changes in pH and temperature and coagulation, and coagulation followed by clay treatment were also performed to study the separation of solids in stickwater. Analysis of the stickwater showed that it contained 4.5% crude protein, 1.4% crude fat, 6.5% total solids, 1.13% ash and 93.1% water. At a wavelength of 575 um, the sample absorbed all the light and the percent transmittance was zero. When diluted 1:100 the percent transmittance was 0.39 at the same wavelength. Measured at 25°C the sample had a viscosity of 9.0 centipoises. The results showed that the precipitation of fat increased with increasing temperatures, while the reverse was true for protein. A pH of 4.0 gave the maximum clarification at all temperatures employed. The viscosity decreased at pH values above and below the original pH of the sample. Among the four different acid activated clays used in this study (trade names Supact‐150, Impact‐150, Impact‐12 and Impact‐1OORR), Impact‐150 was the most effective in protein and fat precipitation, and the degree of separation of these components increased by treating stickwater with a coagulant (aluminum sulfate) prior to treatment with acid activated clay.

The Effects of Changes in pH within a Clay Surrounding a Cementitious Repository

AbstractThe effect of a concrete-based repository on local geological conditions and properties has been explored. As part of a complete description of repository behaviour, a static model of clay-alkali interactions has been set up. Parallel experiments have demonstrated the buffering capacity of clays, and are indicating the chemical and physical changes that may occur when an alkali plume interacts with a clay host rock.

Ultrasonic absorption of bovine serum albumin solutions in the frequency range 60 to 160 kHz.

The ultrasonic absorption of the globular protein bovine serum albumin in aqueous solution has been measured in the frequency range 60 to 160 kHz using a 2-1 spherical resonator. The effect of pH change and of the denaturants urea, guanidine hydrochloride, and sodium dodecyl sulfate on the absorption loss has been studied. It is concluded that a significant ultrasonic absorption process exists which is related to structural helix-coil transition equilibria. For native protein the maximum loss appears to occur at a frequency at least as low as 70 kHz for a pH of about 4.2. This loss process is distinct from those arising from proton-transfer equilibria perturbations which are manifest at pH 3.2 and 11.6 and at peak frequencies of 400 kHz and above.

非脱分極性筋弛緩薬の作用に及ぼす酸-塩基平衡の影響

非脱分極性筋弛緩薬の作用に及ぼす酸-塩基平衡の影響

Isomorphism on a physical system of the Hodgkin-Huxley equations for sodium conductance: Toxin allosteric effects and gating currents

An isomorphism on a physical system of the Hodgkin-Huxley equations for sodium ion conductance in the nerve membrane is derived. The physical system consists of 8 states. It shows that the voltage dependence of the sodium conductance arises from a change in ionization of the molecule that provides the ion-selective conductance channels. It associates reversibly with singly charged (H+?) and doubly charged (Ca++?) ions. The inactivation process is the result of the associating of an ionized particle by half of the states. The effect of toxins and narcotics in blocking or inactivating sodium conductance can be understood as an enzyme or allosteric change of the standard free energy difference of the molecule that provides the sodium channels. The effect of changing pH and Ca++ substrate concentration on the sodium conductance is predicted. The gating charge current is predicted. The time constant predicted is in agreement with experiment.

Effect of changes in pH, in osmolarity, or in temperature on food intake

The thermogenic potential of food is one of the most likely factors to offer a basis for quantitative control of food intake, and is probably the one best fitted to serve as an intrinsic food factor.

Removal of dissolved aluminum released by acid rain using decaying leaves II. Effects of concentration of leaves aluminum, and other cations

Abstract The nature of the interaction between aluminum ions and leaves has been investigated. The effects of several factors including the concentratlon of leaves, the concentration of aluminum, and the presence of competing ions on the uptake of aluminum by leaves have been studied. Releasing aluminum from leaves by the effect of changing pH or the addition of foreign ions has been also studied. Results showed that increasing the leaf concentration increased removal of aluminum; the cations Zn2+, Ni2+, Pb2+, Cd2+, Mg2+, Fe2+, and Co2+ competed with aluminum and reduced its uptake but Ca2+ did not compete.

Ultrasonic absorption of bovine serum albumin solutions in the frequency range 200 kHz-1 MHz.

The ultrasonic absorption of solutions of two electrolytes, magnesium and manganous sulfates, and also of the globular protein bovine serum albumin, has been measured using small volume spherical resonators at frequencies in the range 200 kHz-1.2 MHz. The principles of the technique are discussed and absorption values obtained for the electrolyte solutions at 20 degrees C are compared with existing values using other methods. For BSA, measurements were made at 8 degrees C over a range of pH values. Under both acid and alkaline conditions, excess losses at megahertz frequencies were found to persist down to at least 200 kHz. A new loss peak at approximately 400 kHz has been found at pH 3.2.

Physiological effects of pH changes on colloid osmotic pressures

Our purpose was to explore the effects of variations in pH, particularly in the physiological range, on the colloid osmotic pressure (COP) of the body's fluids. Theoretically, changing pH would alter the electrical charge density on plasma proteins and the interstitial ground substance, thereby altering plasma and interstitial protein osmotic pressure as well as interstitial fluid pressure. We found that the COP of human plasma, human albumin, bovine albumin, and Wharton's jelly from human umbilical cords increased linearly as pH increased over the range of 6.0-8.0. COP of plasma and the albumins all displayed essentially the same sensitivity to pH. At equal concentrations, hyaluronate in umbilical cords was approximately 16 times more sensitive to pH than was plasma. Dextran 70 displayed no COP dependency on pH. For plasma, the albumins, and hyaluronate the pH dependence of COP on pH also decreased linearly with concentration (C in g/dl). For plasma and the albumins over the physiological range of pH, COP = COPpH 7.4 [1.00 + 0.01C (pH -7.40)] at 37 degrees C. The data suggest that, relative to the normal net transcapillary pressure gradient, physiological variations in pH affect plasma COP as well as interstitial fluid pressure and thus may play a significant role in regulating the body's fluid distribution.

Polarographic behaviour of the redox dimer diethyleneviologen dibromide in water

The polarographic behaviour of a paraquat dimer diethyleneviologen dibromide in acidic solutions of varying pH is reported and discussed. The system revealed diffusion controlled irreversible electron-transfer processes at the dme producing two waves over the pH range 1.40–5.80 and a single wave at pH 6.75. The effects of changes in pH, depolarizer concentration and mercury pressure on the wave characteristics have been critically examined and a tentative mechanism for the reduction processes corresponding to both the cathodic waves is proposed. The pH-dependence of the half-wave potentials and relative heights of both wave appear to suggest that the system conforms to a protonation equilibrium where reductions of the protonated and the unprotonated form of the compound proceed with the involvement of H + ion(s) giving rise to two waves, respectively. An approximate value ( K = 31.6 × 10 −2; μ = 0.1 M) for the dissociation constant of protonated compound was estimated on the basis of the variation of limiting currents with pH for both waves, at a known concentration and mercury pressure.

Effects of changes in pH, medium, and inoculum size on the in vitro activity of amifloxacin against urinary isolates of Staphylococcus saprophyticus and Escherichia coli.

The in vitro activity of amifloxacin (WIN 49375), a new fluoroquinolone, was compared with the activities of antimicrobial agents that are commonly used for the treatment of urinary tract infection (cinoxacin, cephalexin, gentamicin, amoxicillin, trimethoprim, and trimethoprim-sulfamethoxazole) against 25 strains of Staphylococcus saprophyticus and 28 strains of Escherichia coli. Bacterial strains were isolated from urine specimens of college women with acute urinary tract infections. Bacterial isolates were more susceptible to trimethoprim-sulfamethoxazole, trimethoprim, and amifloxacin than to the other drugs tested. The in vitro activity of amifloxacin against S. saprophyticus had an inverse relation to increases in the pH of the test medium. Changes in the type of culture medium had no effect on the in vitro activity of amifloxacin. There was a direct relationship between increases in inoculum size and the MICs of amifloxacin.

Studies on water hyacinth as a biological filtre for treating contaminants from agricultural wastes and industrial effluents.

The aquatic weed--water hyacinth [Eichhornia crassipes (Mart) Solms] showed a remarkable capacity to withstand the effects of pH changes ranging from 5 to 8 in the aquatic environment. Growth continued to be normal except when placed for longer periods in medium containing iron ions at pH 3.3. The ability of this plant to neutralize some very acid solutions of heavy metals such as salts of copper, cadmium and zinc individually and in combinations, is being reported. Plants placed in pure acid and alkali solutions were also able to neutralize the medium. Calcium appears to play an important role in the mechanism involved in the adaptability of these plants to such environments.

Evidence for electroneutral chloride transport in rabbit renal cortical brush border membrane vesicles.

Controversial evidence exists as to whether electroneutral Cl-OH exchange occurs across the proximal tubular brush border membrane of the mammalian kidney. To help resolve this controversy, we carried out a series of experiments using rabbit renal cortical brush border membrane vesicles to determine the effect of changes in pH on 36Cl uptake across this membrane. Reducing pH equally inside and outside of the vesicle stimulated Cl-Cl exchange as well as chloride uptake. A proton gradient (out greater than in) stimulated and caused an overshoot in unidirectional Cl uptake. All three of these processes were inhibited by 4-acetoamido-4-isothiocyano-2,2-disulfonic stilbene. Valinomycin with K+ out-in added to shunt any proton diffusion potential, minimally inhibited pH gradient-dependent Cl uptake, and carbonyl cyanide p-trifluoro-methoxyphenyl hydrazone (FCCP), added to increase the proton diffusion potential, minimally stimulated pH gradient-dependent Cl uptake. Sodium-glucose cotransport (an electrogenic system) was used to assess the efficacy of these ionophores. FCCP markedly enhanced and valinomycin markedly inhibited pH gradient stimulated sodium-glucose cotransport. Valinomycin added to vesicles with a 180/0 meq K+ out greater than in gradient stimulated less Cl uptake than a 6.0/7.5 pH out greater than in gradient. We conclude that these results provide strong evidence for the existence of an electroneutral Cl-OH exchanger or Cl-H symporter in this membrane.

Electroflotation of chalcopyrite fines with sodium diethyldithiocarbamate as collector

Electroflotation tests were conducted with a chalcopyrite fines-sodium diethyldithiocarbamate system with normal variables such as effect of concentration, pH of the collector and conditioning time, separately with oxygen and hydrogen bubbles generated electrolytically. Studies were attempted to check the effect of pH changes and electrolyte gases on the surface products. The surface products were extracted with carbon tetrachloride and analysed by UV-visible and I.R. spectrophotometric methods. It was found from the results that the qualitative nature of the surface product was unaffected by the above parameters.