Variations In Hydrogen Ion Concentration Research Articles

Respiratory CO2 response depends on plasma bicarbonate concentration in mechanically ventilated patients

ObjectiveThere is controversy about the effects of high plasma bicarbonate concentration ([HCO3−]) and the CO2 response test. We analyzed the relationship between [HCO3−] and the variation in hydrogen ion concentration (pH) for a given change in PaCO2, and its effects upon CO2 response. DesignA retrospective study was carried out. SettingTwo intensive care units. PatientsSubjects with and without chronic obstructive pulmonary disease (COPD), at the beginning of weaning from mechanical ventilation. InterventionsThe CO2 response was evaluated by the re-inhalation of expired air method, measuring the hypercapnic ventilatory response (ΔVE/ΔPaCO2) and hypercapnic drive response (ΔP01/ΔPaCO2), where VE is minute volume and P0.1 is airway occlusion pressure 0.1s after the initiation of inspiration. Main outcome measures[HCO3−] and CO2 response. ResultsA total of 120 patients in the non-COPD group and 48 in the COPD group were studied. COPD patients had higher mean [HCO3−] than non-COPD patients (33.2±5.4 vs. 25.7±3.7mmol/l, p<0.001). In both non-COPD and COPD patients we observed a significant inverse linear relationship between [HCO3−] and pH change per mmHg of PaCO2 (p<0.001), ΔVE/ΔPaCO2 (p<0.001) and ΔP0.1/ΔPaCO2 (p<0.001). ConclusionsThere is an inverse linear relationship between [HCO3−] and the variation of pH for a given change in PaCO2 and the CO2 response.

Electrochemical Micromachining Microstructure Lattice on Magnesium Alloy Surface

Micromachining of magnesium alloy by confined etchant layer technique (CELT) was investigated. The variation of hydrogen ion concentration on the electrode surface during the electrochemical process was explored for some thermodynamically available "etchant-scavenger" systems, and their corrosion rate to magnesium alloy was measured. An effective electrochemistry "etching-scavenging" system was selected. Using NaNO2 as precursor for electrochemically generating etchant HNO3, NaOH as scavenger, and small amount of Na2SiO3 as inhibitor, 3-D microstructure lattice on a mold was replicated onto the magnesium alloy surface. The microstructures processed were approximately the negative copy of the ones on the mold. Sub-micrometer scale resolution was reached. The result suggested that CELT could be applied to machine the 3-D microstructure on magnesium alloy surface, which had potential to be used for the fabrication of micro electromechanical systems (MEMS).

Ion exchange studies of U(VI) from aqueous Arsenazo-III solutions using AG-2X8, Dowex-50WX8 and Chelex-100 resins

The distribution of U(VI) between the anion exchanger AG-2X8, the cation exchanger Dowex-50WX8 and the chelating resin Chelex-100 and aqueous solutions of Arsenazo-III at different pH values was studied. The concentration of Arsenazo-III was in the range of 1.53·10−4–1.23·10−3M. Equilibrium pH was varied from 1.0 to 8.78 while U(VI) original concentration was held constant at 3.39·10−4M. The effect of Arsenazo-III concentration and the variation of hydrogen ion concentration on U(VI) species formed in solution as well as the sorbed species was discussed. Use was made of IR spectroscopy to investigate the sorption behavior. The sorption of some interfering ions such as Th(IV), Zr(IV) and Ce(III) on the resins used at optimum conditions for the sorption of U(VI) was also investigated.

ラップ液のpHに関する研究(第2報)

The measuring method using the variation of hydrogen ion concentration of lapping liquid was offered to appraise the state of lapping process. In the first report, it was described that the measuring method was very effective for estimating the state of crushed abrasive grains, the working pressure, and the optimum concentration. In this experiment, the basic experimental results were applied to the system which was continuously supplied the lapping compound obtained by mixing abrasive grains with purified water. The following results are experimentally confirmed: (1) The variation of working pressure, density of abrasive grains in lapping compound, and workpiece surface area can be detected in processing by measuring hydrogen ion concentration of lapping liquid. (2) The measuring method using the variation of hydrogen ion concentration of lapping liquid can also be applied to the lapping of alumina ceramics using the diamond abrasive grains.

Complexes of Cu(II) with halocarboxylic acids

The compositions and stability constants of the Cu(II) complexes with the following acids: bromoacetic, iodoacetic, propionic, α- and ß-bromopropionic, ß-chloropropionic, α,ß-dichloropropionic, ß-iodopropionic, α,α-dimethylpropionic, isovaleric and α-bromoisovaleric were determined. Studies were carried out by means of spectrophotometric measurements of the corresponding Bjerrum solutions and by the potentiometric method of measuring variations in hydrogen ion concentration. Stability constants were calculated by several graphical methods.

Computer simulation of respiratory control system

AbstractThe respiratory system in a human body is a control system for maintaining the stability of the body against the variations of the external environment. In the system, the gas concentration in the alveoli and the blood play an important role as a source of information. A computer simulation of the respiratory system is performed based on a model in which the diffusion phenomenon and the gas transportation delay are incorporated. Also, analyses of the response of the system to a variation of the control mechanism as well as of the overall inspired gas components in the system are conducted. The simulation model used in this paper is largely composed of two components, i.e., the control system itself and several kinds of body tissues, representing a whole body. The system to be controlled is the vascular circulatory system which connects the lungs, the brain and the body tissues. O2, CO2 and N2 are carried through the system. On the basis of this fact, the external respiration in the lungs and the internal respiration in the body tissues can be expressed by equilibrium functions, representing the gas exchange by the diffusion phenomenon, the variation of hydrogen ion concentration in the blood, and the quantity of oxidized hemoglobin. Utilizing the model, the variation of the respiratory system in response to the inspiration of air lacking O2 as well as to the possible damage occurring within the system are investigated.

CIRCULAR DICHROISM STUDIES OF SUBSTANCE P AND ITS C‐TERMINAL SEQUENCES

CD spectra of substance P (SP) and its C-terminal partial sequences have been measured in diluted aqueous solution including variation of hydrogen ion concentration. In the far u.v. region there is an overlapping of the amide CD absorption by the CD of the phenylalanine residue aromatic side chains (217-220 nm). This complex CD absorption is reduced during changes from acidic to alkaline pH, especially in those cases where a phenylalanine residue is at the N-terminus of the peptide chain. These CD changes dependent on pH are due more to charge effects on the aromatic chromophores than to substantial conformational changes. However, solvation effects on the conformational features of SP peptides caused by the deprotonation of the amino groups have to be taken into account. CD and potentiometric titrations indicate that the N-terminal alpha-amino groups of the SP peptides in general are freely accessible to the solvent. Our studies did not give any evidence of the occurrence of ordered structures of SP peptides in diluted aqueous solution.

Changes in the kinetic behaviour of threonine transport into Trypanosoma brucei elicited by variation in hydrogen ion concentration.

1. The dependence of V and V/K(m) for threonine transport into Trypanosoma brucei upon the external concentration of H(+) was studied. 2. Two ionizing groups, the alpha-amino group of the substrate and a group at the substrate-binding site of the carrier, were found to influence the observed kinetic behaviour of transport. 3. The pK of the group at the substrate-binding site on the free carrier was found to be 6.95 at 30 degrees C and to be temperature-dependent; its heat of ionization was -63.8kJ, which is outside the range for most proton dissociations and suggests a significant contribution from some other source, possibly the remainder of the carrier or the membrane environment. 4. Binding of substrate caused the pK of its alpha-amino group to shift to a higher value, whereas that of the carrier group shifted to a lower value (6.65 at 30 degrees C). 5. The ionic interaction between substrate and carrier appeared to be involved in the stabilizing of the protonated substrate and the species of the carrier-substrate complex required for the membrane-translocation step. 6. The same ionic species of carrier-substrate complex is required for both substrate dissociation and translocation of the substrate through the membrane. 7. H(+) symport or antiport did not occur during threonine uptake.

Gustatory perception of sour, sweet, and salt mixtures using parotid gland flow rate

The reflex secretion of parotid saliva was utilized to evaluate the stimulatory action of various taste mixtures on human gustatory chemoreceptors. Test solutions consisted of citric acid, sucrose, and sodium citrate. Rates of secretion were determined by measuring the volume produced by a standardized application procedure. The response elicited by the different solutions was determined. The effect of one modality upon another was then studied by combining two solutions at each of four concentrations. Results showed that the addition of citric acid or sodium citrate to sucrose produced a response equal to the sum of the separate constituents. The flow rate obtained from mixtures of citric acid and sodium citrate was less than the sum of the individual components. This apparently was due to the buffering effect causing a decreased hydrogen ion concentration. Although the hydrogen ion concentration decreased to sub-threshold levels, the salivary gland secretion rate was still responsive to variations in hydrogen ion concentration, indicating a synergistic effect when hydrogen and sodium ions were present in the same solution. gustation; taste; gustatory-salivary reflex; parotid gland secretion Submitted on October 1, 1964

Effect of Sodium Chloride and pH on the Rate of Neutralization of Cypridina Luciferase by Specific Antibody

Summary The effect of sodium chloride concentration and pH on the kinetics of the neutralization of Cypridina luciferase by antiluciferase γ-globulin has been investigated. Determination of the rate of neutralization in the presence of excess γ-globulin showed that approximately 60% of the initial activity was neutralized according to pseudo-first order kinetics. The rate of neutralization increased on lowering the sodium chloride concentration and decreased on increasing the salt concentration. The rate also increased in going from pH 7.0 to 5.4 at low salt concentrations, but was insensitive to variation in hydrogen ion concentration at high salt concentrations. At low ionic strengths, the observed results conformed to the predictions of the Brönsted theory of the primary salt effect on reaction kinetics. Consequently, the rate changes observed in the presence of sodium and chloride ions were considered as being due to their effect on the “activity” of an intermediate “activated complex.” Alternatively, the effect of salt and hydrogen ion concentration on reaction rate was also considered in terms of a modified diffuse double layer affecting the collision frequency of the molecules. Determination of the rate constants at varying hydrogen ion concentrations, and subsequent analysis of the data in terms of an interaction between a single ionic species of luciferase and antibody, indicated the involvement of active groups possessing pK1 = pK2 = pK3 = 5 and pK4 ≧ 8.

Some Properties of a Bovine Enterovirus

The properties of a virus isolated from the faeces of a normal calf are described. This virus (VG(5)27) was found to be antigenically similar to the LC R4 virus isolated in the U.S.A. by Kunin and Minuse (1958). VG(5)27 virus is approximately 23 mμ in size, and is relatively thermostable. It is not inactivated by ether or by the chloroxylenol type of disinfectant, but is rapidly inactivated by disinfectants containing chlorine, and by formalin. VG(5)27 virus is not susceptible to variations in hydrogen ion concentration. The virus does not cause lesions or death in laboratory animals, and in this respect differs from the LC R4 virus of Kunin and Minuse.

Interactions of Vibrio cholerae, Shigella flexneri, Enterococci, and Lactobacilli in continuously fed cultures.

SummaryAn apparatus for studying interactions of bacteria in continuous culture has been described. It was shown that, in the dynamic situation of continuously renewed nutrient, growth of V. cholerae is partially suppressed in the presence of growing enterococci and lactobacilli, and that the inhibition was due largely or entirely to the enterococcus and took place under both aerobic and anaerobic conditions.The fundamental cause of the inhibition of cholera vibrios by enterococci is not known, but is not due to the inhibitory effect of variation of hydrogen ion concentration, and probably cannot be attributed to competition for nutrients.

Studies on the Growth of Marine Phytoplankton I.Asterionella Japonica Gran

A planktonic marine diatom, Asterionella japonica, has been grown in unialgal, but not bacteria-free, culture under controlled conditions and its growth has been measured by means of optical density determinations and cell counts in combination.The relative growth constant has been found to be usually between 0·7 and 1·2 loge units per day, and to be little affected by variation of the concentration of nitrate, phosphate and silicate within wide limits. Rapid growth occurred in waters having salinities between 20 and 40‰ S. The optimum temperature for growth was 20–25° C and the optimum light intensity from 4000 to 10,000 lux. The relative growth rate was affected most markedly by variation in hydrogen-ion concentration. This was manifest in stagnant cultures in which the rise of pH above 8·3, caused by absorption of carbon dioxide, resulted in the inhibition of growth. This could be countered by increased aeration or by the addition of the buffer tris(hydroxymethyl)aminomethane.Evidence has been obtained which suggests that A. japonica requires a thermostable substance present in natural sea water and that a thermolabile substance stimulating its growth is produced in culture.Final yields of the order of 4000 cells per mm3 were obtained and, within limits, were dependent on the amounts of nitrate and silicate supplied. The nitrogen requirements per cell was determined as 0·255 μμg atom. Indications were obtained of the presence of a growth-inhibiting substance in the filtrates from old cultures.The optical density of the cells was increased at high nitrate concentrations and when exhaustion of silicate prevented cell division.

The effect of eugenol and oil of cloves on the growth of microorganisms

Bacterial species vary in their individual sensitivity to either oil of cloves or eugenol. B. pyocyaneus (Ps. aeruginosa) was markedly resistant. Variation in hydrogen-ion concentration had no appreciable effect on the activity of clove oil or eugenol. Incorporated in a paste with zinc oxide, eugenol, or oil of cloves still retains definite antibacterial properties.

Stability of Cake Batters Effect of Variation in Hydrogen-Ion Concentration

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStability of Cake Batters Effect of Variation in Hydrogen-Ion ConcentrationEmily GreweCite this: Ind. Eng. Chem. 1938, 30, 6, 719–722Publication Date (Print):June 1, 1938Publication History Published online1 May 2002Published inissue 1 June 1938https://doi.org/10.1021/ie50342a022RIGHTS & PERMISSIONSArticle Views39Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (572 KB) Get e-Alerts

Sterilizing Velocities of Chlorine and Chloramine Under Varying Conditions of Organic Load and pH

The investigations of Holverda (1) and of Baker and Schmelkes (2) indicate that the variations in data on the sterilizing velocity of chloramines are, in part at least, due to variations in hydrogen ion concentration. These experiments and those of others, Gerstein (3) and Hinman and Beeson (4), were with waters carrying none or negligible amounts of organic matter. Gerstein carried out experiments on Lake Michigan water, but does not mention its organic content or chlorine demand. Hinman and Beeson worked with waters of known but low organic load. That hydrogen ion concentration is intimately related to the velocity of sterilization is well recognized, but the effect on this velocity of variations in organic load have not been adequately investigated. The object of the present studies were: 1. To compare the velocity of chloramine sterilization of water at various hydrogen ion concentrations. 2. To compare these velocities in waters of varying organic load. The studies were entirely on a laboratory scale, each run consisting of a 250 cm.3 volume containing the organic matter, test organisms and sterilizing agent. Hinman and Beeson's4 procedure of ammonia and chlorine application were followed. The chlorine solution was made by bubbling chlorine gas through

PREPARATION AND HEAT DENATURATION OF THE GLUTEN PROTEINS

Gliadin prepared by several different methods had the same nitrogen content and distribution. The critical peptization temperature (C.P.T.) in 60% alcohol and viscosity in 30% urea-buffer solutions, however, showed considerable variation, preparations of high C.P.T. (low solubility) being more viscous. This variation in the physical properties is explained by fractionation or denaturation incidental to the method of preparation.Gluten precipitated from 30% urea solutions at salt concentrations varying from 0.1 to 0.5 of saturation, yielded fractions that varied continuously in their gliadin and glutenin content, as judged from their percentage of arginine nitrogen.Gluten dispersed in buffered 30% urea solutions showed no change in viscosity during 101 hr. after the gluten was completely dispersed. A variation of hydrogen ion concentration between pH 6.0 and 6.95 had little effect on its viscosity. Heating at 70 °C. caused a marked decrease in the viscosity of this dispersion during the first hour. When gliadin dispersions are heated as above only samples having a high initial viscosity and C.P.T. become less viscous. Heating gliadin of natural moisture content (12 to 14%) at 70 °C. for varying periods of time did not change significantly its subsequent C.P.T. and viscosity in 60% alcohol. More severe heat treatments at higher moisture contents rendered the gliadin insoluble in 60% alcohol. Dilute alcoholic extracts of heated flours contained less protein than those of unheated controls. However, the C.P.T. of the former was lower than that of the latter. It is concluded from these experiments that when the gluten proteins are subjected to elevated temperatures, the glutenin fraction is first affected, next the gliadin fractions of low solubility, and finally, under severe conditions, all of the gliadin is denatured.

Diagnostic Significance of Precipitin Tests With Anderson Phosphatide Fractions from Human, Bovine, and Avian Tubercle Bacilli.

Working in cooperation with the Research Committee of the National Tuberculosis Association, Drs. F. R. Sabin, C. E. Forkner, and the writer, in this laboratory, have been assaying biologically during the past 3 years the various chemical fractions obtained from the tubercle bacillus by Drs. T. B. Johnson and R. J. Anderson of the Sterling Chemistry Laboratory, Yale University. The investigation includes a parallel study of the chemistry and biology of several members of the acid-fast group of bacteria grown in large quantities by Mulford and Parke, Davis under standard conditions on Long's synthetic media. It has been found that the phosphatide fraction isolated from the tubercle bacillus by Anderson contains an active principle capable of stimulating and maturing monocytes and epithelioid cells. This phosphatide fraction from the human tubercle bacillus H-37 has been shown by Pinner to act as a complete antigen when given intravenously in animals, as proven by precipitin and complement fixation tests. We have confirmed this finding with reference to the precipitin reaction. Readings are made after 5 minutes at room temperature, after 2 hours at 38° C., and after 24 hours in the ice-box. Pseudo-positive reactions are thus avoided. Considerable experience in reading the tests is necessary for accurate determinations. Variations in hydrogen ion concentration, pH 2.5 to 6.02, have had no influence on the reaction. The sera of normal rabbits have been found to give a positive precipitin test in low dilutions only, 1-20 with dilutions of a 1% antigen, or with a fixed antigen with only the undiluted serum. The exceptional rabbit direct from stock showing higher titres is now discarded for all experimental work in fraction testing and other studies on tuberculosis in this laboratory. There is some evidence that small variations in the phosphatide precipitin titre may accompany a non-tuberculous monocytosis in blood and connective tissues.

Notes on the Hydrogen Ion Concentration, Excess Base, and Oarbon‐dioxide Pressure of Marine Aquariu u Waters.

Summary. Water from tanks and reservoirs at the Societ.y's Aquarium has bee11 examined over a period of a year with respect to excess base, hydrogen ion concentration salinity, oxygen content, and pal tial pressure of carbon dioxide. Similar estimations have been carried ont on fresh sea‐water sent froin tile Bay of Biscay, Plymouth outside sea‐water, Plymouth dquariuin water, aud tank water from University College Aquarium, London. In all cases the values are found to deviate from the normal to a greater or less extent. Plymouth Aquarium water maintains a nearly constant pH, as it is treated with lime, but is supersaturated with carbon dioxide. The Society's Aquarium shows the greatest variation in hydrogen ion concentration and partial pressure of carbon dioxide, but the animals adapt themselves to this. The rate at which the excess base alters in the Aquarium when a new consignment of water is used was examined. The advantages of liming aquarium water are discussed.

A Note on Haemerythrin

ABSTRACTThe effect of change of temperature on the dissociation curve of oxyhaemerythrin is shown. The heat of combination between haemerythrin and oxygen has been calculated to be 10,350 calories per gramme molecule of oxygen. It has been shown that oxyhaemerythrin is only stable over a small range of pH. The pigment appears to be most stable at pH 8·0 and 9·0. Variation of hydrogen-ion concentration between pH 6·0 and pH 10·0 appears to have little effect on the dissociation curve of oxyhaemerythrin. Oxyhaemerythrin can be converted to a yellow “methaemerythrin” by the action of oxidising agents. The change occurs spontaneously at slightly acid hydrogen-ion concentrations. Attempts to show the presence of haem in the haemerythrin molecule have been unsuccessful. The nature of the purple colour produced by the action of concentrated H2SO4 on a solution of oxyhaemerythrin is discussed. Photographs of the absorption spectra of oxyhaemerythrin, methaemerythrin and the H2SO4 product of oxyhaemerythrin are shown.