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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The extraction of Catechol Violet, Chrome Azurol S and Eriochrome Cyanine R with chloroform solutions of tri-n-octylamine (TOA), TOA hydrochloride and Aliquat 336 has been investigated. From the extraction isotherms, absorption spectra of the organic phases and dependence of the extraction coefficients on extractant concentration, it was found that the singly-charged anions HL(-) are extracted preferentially, but acidic groups other than sulphonate can also form ion-pairs with alkylammonium cations at higher pH values of the aqueous phase, and at high acidity these dyes can be extracted other than by an anion-exchange reaction. The three dyes (especially Eriochrome Cyanine R and Chrome Azurol S) were strongly extracted with the liquid anion-exchanger used and Aliquat 336 was a better extractant than TOA or TOA hydrochloride. The absorption spectra for the organic phases containing Chrome Azurol S and Eriochrome Cyanine R depended on the extractant used.
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PMID:Extraction of catechol violet, chrome azurol S and eriochrome cyanine R with chloroform solutions of liquid anion-exchangers. 1896 20

For extraction studies a "filter-probe" porous Teflon membrane phase-separator is used in conjunction with a spectrophotometer fitted with a small-volume flow-cell and a peristaltic pump to measure absorbance of the organic phase as a function of aqueous phase pH. Acidity constants of monoprotic (HA) and diprotic (H(2)A) acid benzothiadiazines have been measured with the apparatus. Accurate pK(a), values for these compounds are difficult to measure by other techniques. Mixtures of n-octanol and chloroform in various proportions can be used as the organic phase in order to adjust the distribution coefficient of the neutral species to give optimum precision and accuracy in measurement of the pK(a) values.
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PMID:Measurement of acidity constants of benzothiadiazines by solvent extraction with use of a membrane phase-separator. 1896 47

A selective spectrophotometric determination of copper is based on extraction of the copper-ferron complex with tribenzylamine in chloroform at low acidity, and measurement of the absorbance of the yellow extract at 410 nm. Beer's law is found to hold up to 8 microg/ml copper concentration. Of 30 elements tested, only molybdenum interferes. The ratio copper:ferron:tribenzylamine in the extracted species is 1:2:2.
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PMID:A selective spectrophotometric method for determination of copper with ferron. 1896 99

A solution of n-octylaniline in chloroform extracts rhenium selectively from 0.12-0.16 M nitric acid medium. Rhenium from the organic phase is backstripped with 5% aqueous ammonia solution and estimated spectrophotometrically with 5-chloro-2-hydroxythiobenzhydrazide (5-Cl-2-OHTBH). 5-Cl-2-OHTBH forms a blue complex with rhenium on heating in the acidity range 0.40-3.5 M HCl. The complex is extracted into chloroform and its absorbance is measured at 580 nm. The complex is stable for more than 12 h with a molar extinction coefficient of 9.0 x 10(3)l mole(-1) cm(-1) and a Sandell sensitivity of 0.019 mug cm(2).
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PMID:Spectrophotometric estimation of rhenium with 5-chloro-2-hydroxythiobenzhydrazide after its extraction separation using n-octylaniline. 1896 8

Water, methanol and chloroform extracts of Landolphia owarensis were investigated for their effects on gastric acid secretion and ulceration in male albino rats. Two models of gastric lesion induced in experimental Wistar rats-HC1/ethanol-induced gastric lesions and Pylorus ligation-induced gastric lesions-were employed. In both models, the antiulcer activity of LA was compared with that of cimetidine (100 mg kg p.o.). In the HCl/Ethanol model, ulcer index and mucus production was determined. In pylorus ligated rat, ulcer index, mucus production, total volume of gastric juice and gastric acidity level were measured. Pre-treatment of animals with the aqueous extracts (100mg/kg and 200mg/kg) orally once daily for two weeks significantly reduced formation of ulcers induced by HCl/ethanol mixture, the percentage inhibition being 43.8 % and 55.27 % respectively. The chloroform extract afforded the least protection with 23.07 % and 14.77 % inhibition. This was also accompanied by significant increases in gastric mucus production. In pylorus ligated rats, total volume of gastric juice and gastric acidity was significantly decreased as compared to control group, to levels comparable to that produced by cimetidine. The results indicate that the leaf extracts of LO contains antiulcer principles.
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PMID:Antiulcer and gastric antisecretory effects of Landolphia owariensis extracts in rats. 1943 9

A novel biocomposite of carbon fiber (CF) reinforced hydroxyapatite (HA)/polylactide (PLA) was prepared by hot pressing a prepreg which consisting of PLA, HA and CF. The prepreg was manufactured by solvent impregnation process. Polymer resin PLA dissolved with chloroform was mixed with HA. After reinforcement CF bundle was impregnated in the mixture, the solvent was dried completely and subsequently hot-pressed uniaxially under a pressure of 40 MPa at 170 degrees C for 20 min. A study was carried out to investigate change in mechanical properties of CF/HA/PLA composites before and after degradation in vitro. The composites have excellent mechanical properties. A peak showed in flexural strength, flexural modulus and shear strength aspects, reaching up 430 MPa, 22 GPa, 212 MPa, respectively, as the HA content increased. Degraded in vitro for 3 months, the flexural strength and flexural modulus of the CF/HA/PLA fell 13.2% and 5.4%, respectively, while the shear strength of the CF/HA/PLA composites remains at the 190 MPa level. The SEM photos showed that there were gaps between the PLA matrix and CF after degradation. Water uptake increased to 5%, but the mass loss rate was only 1.6%. The pH values of the PBS dropped less than 0.1. That's because the alkaline of HA neutralize the acid degrades from PLA, which can prevent the body from the acidity harm.
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PMID:Preparation and mechanical properties of carbon fiber reinforced hydroxyapatite/polylactide biocomposites. 1948 80

Securigera securidaca belongs to the family Fabaceae is used in Iranian folk medicine to treat gastric disturbances. The present study was undertaken to evaluate the Securigera securidaca seed hydroalcoholic extract (SSE) and its subfractions for their gastroprotective effect in rat. Acute gastric ulceration in rats was produced by oral administration of ethanol (100%; 1 mL/200 g of body weight) or water immersion restraint-stress (5 h, water immersion restraint stress at 20-22 degrees C). Ranitidine (100 mg kg(-1), p.o.) was used as the reference antiulcer drug. After ethanol administration, the gastric wall mucus was examined. Chronic gastric ulceration was produced by injection of acetic acid in rat gastric subserosa. The antisecretory effect of the extract and its subfractions (ethyl acetate, chloroform and aqueous fractions) were investigated in pylorus-ligated rats. Administration of SSE significantly inhibited gastric mucosa damage induced by ethanol, water immersion restraint-stress and acetic acid in a dose-dependent manner. In pylorus ligature rats, SSE and its subfractions significantly reduced the basal gastric acid secretion and total acidity; moreover, it inhibited the increase in total acidity induced by carbachol. However, the antisecretory effect of the chloroform fraction was more potent than two other fractions. Administration of SSE did not affect the gastric mucus production. The results obtained in the present study indicate that the SSE has gastroprotective and antisecretory effects on gastric mucosa in rats.
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PMID:Antiulcerogenic effect of Securigera securidaca L. seed extract on various experimental gastric ulcer models in rats. 1963 Feb 13

1. Under certain conditions, general autolysis does not begin immediately upon the removal of the organ from its circulation. This latent period is more apt to be present in those cases in which the tissues have been temporarily cooled on account of the use of a cold saline diluent or in which the percentage concentration of the inorganic salts (calcium or potassium), of the tissues have been changed by dilution with a sodium chloride solution. The presence of blood and absence of fats and of glycogen in the cells act as important factors in prolonging the latent period. 2. Attempts to produce an alkaline reaction (phenolphthalein) in the tissue resulted negatively. Solutions of disodium hydrogen phosphate and of sodium bicarbonate when added to the liver tissues gave a mixture which was acid to phenolphthalein and had no apparent effect upon autolysis. 3. The addition of antiseptics-chloroform and toluol-markedly decreased the rate of autolysis. Ordinary light produced no effect. 4. Ethyl butyrate when added to the tissue became hydrolysed into butyric acid; the formation of this acid in the mixture caused a decided acceleration in the autolytic rate. The acidity of a solution of dihydrogen sodium phosphate failed to produce a similar result. 5. The figures for the changes in the depression of the freezing-point, non-coaguable nitrogen and reaction of the autolytic mixture do not parallel one another. In some experiments a marked increase in the depression of the freezing-point was unaccompanied by augmentation of non-coagulable nitrogen. 6. General autolysis is the sum total of proteolytic, amylolytic and lipolytic factors. Each of these autolytic factors may proceed alone for a time; the rate of one is decidedly influenced by the presence or absence of the others. The acid products which are the result of amylolytic (lactic acid) and of lipolytic (higher fatty acids) autolysis, exert a pronounced augmentative effect upon the commencement and rate of nitrogenous autolysis.
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PMID:THE EFFECT OF CONDITIONS UPON THE LATENT PERIOD AND RATE OF ASEPTIC POST MORTEM AUTOLYSIS DURING THE FIRST TEN HOURS. 1986 44

1. Washed cellular suspensions of pneumonic lungs, previously preserved with chloroform and toluene, contain a protease or proteolytic ferment, derived chiefly from the leucocytes of the exudate. 2. This protease is able to convert horse fibrin to a non-coagulable split product. In a pH range of 4.0 to 8.0 the digestion is slight at the most acid end. With decrease in acidity there is a gradual rise in activity to pH 6.0, and then a sharp increase up to the maximum digestion at pH 8.0. Judging from the amino nitrogen determinations, the most complete splitting occurs at pH 7.0. The degree of autolysis occurring in the pneumonic lung cellular suspension controls suggests that the active enzyme is identical with that causing the digestion of the fibrin. 3. Washed cellular suspensions of normal lungs, previously preserved with chloroform and toluene, contain a proteolytic enzyme which is active in a moderately acid medium (pH 4.0) and essentially inactive in less acid, neutral, and slightly alkaline media.
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PMID:STUDIES ON THE PNEUMONIC EXUDATE : V. THE RELATION OF PNEUMONIC LUNG PROTEASE ACTIVITY TO HYDROGEN ION CONCENTRATION, AND A CONSIDERATION OF THE ORIGIN OF THE ENZYME. 1986 94

1. A method has been outlined by which the enzymes of hemolytic streptococcus may be extracted with comparative ease. 2. The peptolytic enzyme is active between pH 4.4 and 8.7 with an optimum action at pH 7.2. It is destroyed in neutral phosphate solution at a temperature of 57 degrees C. continued for 10 minutes and at pH 5.0 deteriorates slowly at 37 degrees C. Concentration experiments with solutions of the enzyme have shown that it resembles other enzymes. It is exceedingly susceptible to chloroform and its action is inhibited by dilutions of gentian violet. Casein is attacked but serum albumin is not digested after 3 days at 37 degrees C. 3. The invertase is active between approximately pH 5.0 and 8.0 with an optimum of pH 7.0. It is destroyed by a temperature of 52 degrees C. continued 10 minutes at an acid concentration of pH 7.0, or after 6 hours at 37 degrees C. at pH 5.0. At this acidity it is more susceptible to heat than the peptase. 4. The lipase is active above pH 5.6. The greatest activity was observed at pH 7.9. It is completely destroyed after heating to temperatures over 55 degrees C. for 10 minutes and resembles the invertase in its susceptibility to acid.
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PMID:THE PEPTASE, LIPASE, AND INVERTASE OF HEMOLYTIC STREPTOCOCCUS. 1986 48


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