Influence Of Alkali Research Articles

Influence of alkali- and alkaline-earth-metal cations on the ‘salt-induced peptide formation’ reaction

The reaction mechanism of the salt-induced peptide formation from amino acids has been investigated by variation of the inorganic salt delivering Cl– ions and providing the dehydrating effect. Chloride anions proved to be essential to prevent chelate complexation of the second amino acid. Upon exchange of sodium by other alkali- or alkaline-earth elements, peptide formation is still observed. The dipeptide yields are mainly determined by two factors: on the one hand the pH of the solution should be below 3 to prevent CuII-catalysed peptide hydrolysis and give an optimum species distribution for peptide formation, and above 2 to keep proton-catalysed peptide hydrolysis as low as possible; on the other hand by the concentration of the inorganic salt for removing water from the reaction and thus shifting the equilibrium towards the peptide side. The hydration enthalpies of the cations are the determining facto for the initial rate of peptide formation and lead to the series Mg2+ > Ca2+ > Ba2+ > Na+ > NH4+ > K+ > Cs+. In the long run the initial advantage of divalent cations is overruled by stronger hydrolysis due to the lower pH of their solutions. The ion NH4+ is atypical, apparently due to its buffering ability

ポリマーディスパージョンによって形成されたポリマーフィルムの耐アルカリ性に関する2, 3の考察

Polymer dispersions have been used in polymer-modified mortars for many years, and are also being used as sealers for bed concrete of mortar or tile finished exterior walls. This study mainly deals with the stability of polymer films formed with polymer dispersions in alkali environment, and the influence of alkali on the physical properties of the polymer films in polymer-modified mortars. The conclusions obtained are summarised as follows : (1) Homopolymers containing ester linkage and copolymers containing vinyl acetate are less stable in alkali environment, because their chemical structures are altered by the alkali. (2) Polymer films formed with polymer dispersions are used as sealers are apt to deteriorate compared with polymer films in polymer-modified mortars. The reason for this may be explained to be due to the difference of exposure conditions of the polymer films to concentrated alkali such as in pore solution.

Bicyclo[2.2.2]octane-2-spirocyclohexanes, Part 3. Synthesis and Reactions of Mono- and Dibromospirodiisophoranes

Halogenation by the appropriate amounts of bromine or N-bromosuccinimide converts spirodiisophora-3',6-dione successively into the 4'-ax-mono- and 2',4'-diax-dibromo-3',6-dione. The latter is reduced by lithium aluminium hydride to the corresponding 6,3'-ketol. with retention of one or both bromo-substituents, depending on conditions. The bromoketones undergo the Favorski ring-contraction under the influence of alkalis to compounds of the bicyclo[2.2.2]octane-2-spirocyclopentane ring-system . The 13C NMR spectra of the individual products are assigned and correlated with their structures.

A discussion of the paper “influence of alkali on carbonation of concrete, part 2, influence of alkali in cement on rate of carbonation of concrete” by K. Kobayashi and Y. Ono

A discussion of the paper “influence of alkali on carbonation of concrete, part 2, influence of alkali in cement on rate of carbonation of concrete” by K. Kobayashi and Y. Ono

A reply to the discussion of John Bensted of the paper “influence of alkali on carbonation of concrete part 2, influence of alkali in cement on rate of carbonation of concrete”

A reply to the discussion of John Bensted of the paper “influence of alkali on carbonation of concrete part 2, influence of alkali in cement on rate of carbonation of concrete”

Rearrangements of 1-oxa-2-azoles. 4. Synthesis and rearrangement of isoxazole- and 4,5-dihydroisoxazole-3-carboxylic acid amidoximes

Isoxazole- and 4,5-dihydroisoxazole-3-carboxylic acid amidoximes were obtained in the reaction of 5-trifluoromethyl-1,2,4-oxadiazole-3-carbohydroximic acid bromide in the presence of sodium bicarbonate with monosubstituted ethylenes and acetylenes with subsequent opening of the oxadiazole ring. Amidoximes of the isoxazole series undergo rearrangement to aminofurazans under the influence of alkalis.

THE PROMOTER EFFECT OF ALKALI METAL TO SUPPORTED IRON CATALYST IN CARBON MONOXIDE HYDROGENATION, THE INFLUENCE OF ALKALI ON CARBON DEPOSITIONS

The promoter effect of alkali metals on CO hydrogenation was studied on a series of silica supported iron catalysts. Mossbauer spectra of the catalysts show that iron is well dispersed on the silica support. The decrease in chemisorption of carbon monoxide on addition of promoters reveals that alkali covers part of the iron metal surface. The production of olefins, carbon dioxide and long chain hydrocarbons increases with decreasing ionization potentials of the alkali metals added. Hydrogenative decarbidation of catalysts after CO/H2 reaction show that the hydrogenation of the carbon depositions on iron catalysts can be well explained by a series reaction model. The relative reactivity of carbon depositions on well dispersed iron catalysts are strongly affected under the influences of alkali. Addition of alkali metals to iron catalyst may depress the hydrogenation ability of the catalysts.

Influence of alkali on carbonation of concrete, part 2 - Influence of alkali in cement on rate of carbonation of concrete -

It is confirmed through accelerated carbonation tests and exposure tests in the atmosphere using concrete specimens that the rate of carbonation of concrete is higher the higher the alkali content of cement, and it is pointed out that alkali in cement is a factor newly found to have an influence on carbonation of concrete

Influence of alkali on carbonation of concrete, part I. Preliminary tests with mortar specimens

Mortar specimens were made using a total of five kinds of ordinary portland cement including two of different Na 2O-equivalent alkali content (R 2O) and three kinds of varying R 2O to a maximum of 1.5% through addition of NaOH, and accelerated carbonation tests were performed. It was found that the rate of carbonation becomes higher the greater the alkali content of cement, and it was shown through simulation experiments that this trend becomes prominent when there is movement of pore solution

Influence of alkali on pyrolysis of coals

Pyrolysis of several Indian coals of different rank in the presence of NaOH showed that the best yield of hydrogen was obtained from medium rank (C, 83.5%) Poniati-Girimint coal. With this coal, other alkalis (Ca(OH) 2, CaCO 3, Na 2CO 3) gave much less hydrogen, but significantly more methane in the product gas.

The Reaction of Malononitrile with Some Enamines of 1-Indanone Synthesis of o-Aminonitriles of Indenopyridine and Indenothiopyran

(4). The reaction of enamines of 1-oxo-indan-2-carboxylic acid anilides (1) with malononitrile yielded 2-arylcarbamylindenylidene-malononitriles (3), which in alkaline solution underwent cyclization to indenopyridines Enamines of 1-oxo-indan-2-carbothionic acid anilides (2) reacted with malononitrile yielding indenothiopyrans (6), which under influence of alkalis were transformed to indenopyridines (8).

Influence of Polar Groups and Metal Salts on the Residual Currents of Semiconductor Devices Covered with Polyimides

The residual currents of a modified field effect transistor, covered with polyimides containing amido, imino, and carboxylic acid groups, were measured in order to clarify the phenomena causing increased residual currents when larger amounts of unreacted amidic acid groups remain in the coating polyimide layer. Alkoxysilane agents containing imino and amino groups were coated on the transistor surface in order to evaluate effects of these groups on the current. Influence of alkali and transition metal ions, contained as impurities, on the residual current was analyzed by addition of metal salts to the polyimide. Effects of both metal ions on the residual current were compared with those of polar groups such as amido, imino, amino, carboxylic acid, and amidic acid groups in the polyimides.

Influence of alkalinity on effectiveness of additives in lithium greases

The present work has been aimed at studying the influence of excess alkali (LiOH) on the service properties and effectiveness of the additives* SIM (5% by weight), DF-11 (1% by weight), KINKh-2 (5% by weight), MoS= (5% by weight), and of combinations of these additives, in lithium greases. The greases were prepared by compounding AU spindle oil with lithium 12-hydroxystearate (LiOSt) at a concentration of 10% the blended grease was slow-cooled at 2-4~ The concentration of excess alkali was measured and expressed as % NaOH (in accordance with GOST [All-Union State Standard] 6707-76). The alkallnity of the greases was varied from 0 to 1% NaOH. The additives were introduced into the soap-oil melt 1 min before cooling. An investigation of the influence of alkali on the protective properties of the greases (Dynacorrotest instrument [5]) without additives showed that as the alkalinity was increased up to 0.1%, the corrosion rate remains practically unchanged; further increases in the alkali content have an adverse effect on the protective properties of the greases. Excess alkalinity has little effect on such lubricity indexes as the critical seizure load, weld load, and scoring index, but it does improve the antiwear properties: The wear scar diameter D w decreases from 0.65 mm for the neutral grease to 0.45m m for the grease with excess alkali equivalent to 1% NaOH. As the alkalinity is increased, the theological properties generally become worse. Exceptions are the greases with the additive DF-II and with the following combinations of additives: SIM+ KINKh-2, DF-II + MoS=, and SIM+ DF-II. These greases become somewhat stronger (harder) at an alkalinity of 1% NaOH. For the greases with additives, we observed an extremal variation of lubricating properties with increasing alkalinity(Table

Influence of alkalies on the composition of belite-rich cement clinkers and the technological properties of the resulting cements

Contents of alkalies in raw meals of low lime saturation are almost completely bonded in belite-rich clinker. The volatilization rate of alkalies during clinker burning is low. In absence of SO 3, the major portion of alkalies is incorporated in the belite as main clinker phase. The latter absorbing higher concentrations of K 2O than of Na 2O. In the matrix of belite-rich clinkers alkalies are enriched with preferably orthorhombic alkali aluminate being stabilized. Increasing amounts of alkalies incorporated in the belite lattice result in a correspondingly more extensive stabilization of the hydraulically more active modifications α′- and α-belite. Rapid clinker cooling (about 3000 K/min) assists the stabilizetion of high-temperature forms of belite, the hydraulic activity of the stabilized phases is enhanced. The compressive strength of the resulting belite-rich cements after 28 days can be raised by 60 to 100% compared with alkali-free belite-rich cements.

Effect of alkalies on the performance of blast furnace.

The influence of alkalies on the blast furnace operation has been discussed from the data collected from the Iron and Steel Co., Helwan, Egypt. The stability of the alkali compounds formed in the blast furnace was calculated from the thermodynamic data. The model of alkali circulation in the different zones of the furnace, as a function of temperature is proposed. Statistical analysis of alkalies from the input and output materials was calculated and discussed. The effect of alkalies on the partition of manganese and sulphur as well as on the rate of coke consumption was investigated. The relations between the alkali loadings, the basicity and the efficiency of alkali removal by the slag were discussed. Mathematical relations between these different parameters were given and correlated.

Role of alkali in forming structure of lithium greases

The present work has been aimed at studying the influence of the high-temperature holding time ("hot-soak" time) and the melt cooling conditions on the individual stages of grease structure formation, depending on the content of alkali. In preparing the greases we used LiSt obtained in grease manufacture by neutralizing the calculated quantities of HSt with an aqueous LiOH solution. The concentrgtion of LiOH in AU spindle oil was varied broad limits (0.5-0.8% as NaOH). The structurization of the grease was performed with slow cooling (2-4 ~ C/min), with fast cooling (40-50~ and with isothermal crystallization of the melt at 130~ for 60 min. The influence of alkali on the association of soap molecules and the change in the character of this effect, depending on the particular process factors, were investigated on the basis of IR spectroscopic data [4], measurements of the temperature dependence of the dielectric constant s, and measurements of the yield point (GOST [All-Union State Standard] 7143--73). In the spectroscopic studies, the soap concentration was no higher than 3% by weight (90~ mmoles/liter), since with higher contents of LiSt, the optical density of the absorption bands of its associated molecules does not follow the normal rules, even with a minimum thickness of the sample layer in the cuvette.

Influence of alkali on the sulphate resistance of ordinary portland cement mortars

The work described here indicates that the alkali content of an ordinary portland cement (opc) has an influence on the sulphate resistance of mortars made with it. Some criteria regarding the relationships between the C 3A, SO 3 and Na 2O eq contents of an opc to minimise or prevent sulphate expansion of mortars made with it, are suggested.

Transformations of some alkaloids of the carboline series under the influence of alkali

The reaction of quaternized forms of two alkaloids of the β-carboline series — harman and brevicarine — with alkali was investigated. It was established that, under the reaction conditions, the harman derivative undergoes recyclization of the pyridine part of the molecule, whereas in the analogous brevicarine derivative the pyridine ring does not undergo transformations.

Influence of Alkalies on the High Alumina and Fireclay Refractories in the Rotary Cement Kiln

Influence of Alkalies on the High Alumina and Fireclay Refractories in the Rotary Cement Kiln

Influence of Alkalies on the Basic Refractories in the Rotary Cement Kiln

Influence of Alkalies on the Basic Refractories in the Rotary Cement Kiln