Hydration In Water Research Articles

Electrolytic aluminium oxide membranes — a new kind of membrane with reverse osmotic characteristics

Porous aluminium oxide membranes have been produced by a complete anodic oxidation of thin aluminium folia in acid media. The electronic microscopy investigation had shown that the membranes have an asymmetrical porous structure with a very dense barrier layer and that they are, therefore, potentially applicable, in the reverse osmosis field. Investigation of the membrane pure water permeability under pressure differences from 10 to 30 atm gave high initial permeability values (about 100 times higher than those of thermally untreated cellulose acetate membranes) which decreased rapidly during experiments. By heating the membranes above 600°C, or by their additional hydration in hot water, initial permeability decreases, with further decrease during the experiments. In addition, the hydrated membranes have better mechanical characteristics than untreated ones. The separation characteristics of aluminium oxide membranes were tested with aqueous solutions of sucrose and phenol, under the same conditions as in the permeability tests. The membranes exhibited distinct selectivity in both cases.

ChemInform Abstract: STOPPED‐FLOW STUDIES OF CARBON DIOXIDE HYDRATION AND BICARBONATE DEHYDRATION IN WATER AND WATER‐D2. ACID‐BASE AND METAL ION CATALYSIS

Chemischer InformationsdienstVolume 8, Issue 52 Preparative Organic Chemistry ChemInform Abstract: STOPPED-FLOW STUDIES OF CARBON DIOXIDE HYDRATION AND BICARBONATE DEHYDRATION IN WATER AND WATER-D2. ACID-BASE AND METAL ION CATALYSIS Y. POCKER, Y. POCKERSearch for more papers by this authorD. W. BJORKQUIST, D. W. BJORKQUISTSearch for more papers by this author Y. POCKER, Y. POCKERSearch for more papers by this authorD. W. BJORKQUIST, D. W. BJORKQUISTSearch for more papers by this author First published: December 27, 1977 https://doi.org/10.1002/chin.197752147AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume8, Issue52December 27, 1977 RelatedInformation

Stopped-flow studies of carbon dioxide hydration and bicarbonate dehydration in water and water-d2. Acid-base and metal ion catalysis

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStopped-flow studies of carbon dioxide hydration and bicarbonate dehydration in water and water-d2. Acid-base and metal ion catalysisY. Pocker and D. W. BjorkquistCite this: J. Am. Chem. Soc. 1977, 99, 20, 6537–6543Publication Date (Print):September 1, 1977Publication History Published online1 May 2002Published inissue 1 September 1977https://doi.org/10.1021/ja00462a012RIGHTS & PERMISSIONSArticle Views1221Altmetric-Citations141LEARN 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 (757 KB) Get e-Alerts Get e-Alerts

Hydrophobic hydration in mixtures of N,N-dimethylformamide and water enthalpies of solution and heat capacities of tetra- n-butylammonium bromide

Enthalpies of solution of tetra- n-butylammonium bromide have been measured calorimetrically in mixtures of N,N-dimethylformamide ( dmf) + water from 278 to 328 K at 10 K intervals covering the whole mole fraction range. All profiles of enthalpy of solution against composition show endothermic maxima. From a simple hydration model it is possible to calculate the number n of water molecules which surround a hydrophobic alkyl group and the enthalpic effect of hydrophobic hydration in pure water. The latter effect appears to decrease strongly with temperature, while n is almost temperature independent. In addition partial molar heat capacities, C p,2 ∞, of n-Bu 4NBr have been calculated in the dmf + water mixtures; C p,2 ∞ hardly changes in the range from 0 to 0.6 mole fraction of water. In more water-rich regions C p,2 ∞ increases very rapidly towards its value in pure water.

Surface area and pore structure of compressed low-porosity cement pastes

Low-porosity portland cement pastes were prepared by pre-hydration compression at 5, 10, 30 and 70 atmospheres, followed by hydration in liquid water at 25°C for about two years. The thickness of the produced tobermorite sheets was found to depend on the pressure used in the pre-hydration compression. It seems that at the highest compression there is not enough room for complete hydration nor for sheet thickening. The simultaneous changes in the degree of hydration, the pore structure, and the specific surface area of the main hydration product due to pre-hydration compression, could affect the compressive strength measured for the various pastes, and an interpretation is given.

3H-1,2,3,4,6-penta-azaindenes (“8-azapurines.”) Part I. Covalent hydration, syntheses, and reductions

Ionisation constants and ultraviolet spectra show that several 8-azapurines undergo covalent hydration in water, including the cations of 8-azapurine, 2-methyl- and 2-amino-8-azapurine, and the neutral species of 2-hydroxy- and 2-mercapto-8-azapurine. The ready oxidation of the hydrated form to 6-hydroxy-derivatives indicates that hydration produces 1,6-dihydro-6-hydroxy-8-azapurines. Four examples are given in which the insertion of a methyl group in the 6-position prevents this hydration.

Infra-red Spectra of Quaternary Ammonium Compounds adsorbed on Silica-gel ‘Aerosil’

WE have examined by infra-red spectrophotometry the reaction of alkyl trimethyl ammonium bromides of chain-length 4–20 with silica surfaces. For these investigations 10−2 M solutions of the ammonium compounds were added to ‘Aerosil’ powder, which had been conditioned by hydration in water at 100° C for 4 h, dried and ignited at 700° C for 72 h, rehydrated as before and finally dried at 120° C. Hockey1 has shown that this treatment gives a surface containing 4.6 surface silanol groups per 100 A2. Since optimum adsorption was found to occur within the pH range 6.6–8.5, the suspension was adjusted to pH. 1 by the addition of 10−2 M sodium hydroxide solution. After 2 h the silica plus adsorbate was centrifuged out, dried at 120° C, then pressed into a coherent wafer containing 10–15 mg sample per cm2 in a die at 12,000 lb/in.2 for 5 min. The wafer was placed in a gas cell, evacuated at a pressure of 10−5 mm of mercury for 4 h, and the infra-red spectrum recorded on a Perkin-Elmer 237 double-beam instrument.

Mercuric bromphenol blue staining of precipitin lines in agar.

Lines formed by antibody-organ antigen reactions are stained particularly well by a modification utilizing the mercuric bromphenol blue (MBB) mixture of Mazia et al. (Biol. Bull., 104: 57-67, 1953). The agar covered slides are placed overnight in 0.85% NaCI at 4 C, followed by washing for 2 hr in 0.85% NaCI at 25 C. They are then rinsed for 10 min in distilled water, and dried overnight at 37 C. The precipitin lines are fixed by immersing the slides for 25 min in 95% alcohol, followed by 5 min hydration in distilled water. They are stained for 25 min in MBB mixture (HgCI2, 10 gm; bromphenol blue, 0.1 gm; 95% ethanol, 100 ml). Excess stain is removed by immersing in acidified alcohol (95% ethanol, 98 ml; glacial acetic acid, 2 ml). Finally, the slides are passed through alcohol and xylene, and resin-mounted under coverslips.