摘要:
Provided is a process for preparing alumina agglomerates which comprises:(i) treating agglomerates of active alumina with an aqueous medium comprising at least one acid making it possible to dissolve at least part of the alumina and at least one compound providing an anion capable of combining with aluminum ions in solution,(ii) subjecting the agglomerates to a hydrothermal treatment at a temperature in the range of from about 80.degree. C. to about 250.degree. C., and then(iii) thermally activating the agglomerates at a temperature in the range of about 500.degree. C. to about 1100.degree. C.The resulting alumina agglomerates possess exceptional mechanical strength, heat resistance and hydrothermal resistance and are useful as catalysts or catalyst supports.
摘要:
Alkyl carboxylates of the formula:R--CO--O--CH.sub.2 R'are prepared by hydrocarbonylating a compound of the formula:R--CO--O--R'in the simultaneous presence, in the reaction medium, of cobalt, ruthenium, an alkyl iodide and an ionic iodide, the atomic ratio Co/Ru being less than or equal to 1, and the total amount of iodine-containing promoters present in the medium being such that I/Ru is greater than or equal to 5.
摘要:
Process for effecting rapid and homogenous intimate contact of substances which occur in different phases. The process includes a step of producing contact between a helicoidal flow of substances, at least partially in the gaseous state, and a rectilinear flow which is coaxial with the first flow, of liquid or solid substances, at the outlet of a flow passage having a downstream constricted aperture, the amount of movement of the helicoidal flow at the outlet being at least 100 times greater than that of the rectilinear flow. This process can be used in particular for producing mixtures or for drying substances.
摘要:
Tripeptides of the general formula: ##STR1## wherein the symbols R, which may be the same or different represent hydrogen or a fatty acid residue (at least one of them representing a fatty acid residue), R.sub.1 represents hydroxy, amino or alkoxy and R.sub.2 and R.sub.3, which may be the same or different, represent hydrogen, carboxy, carbamoyl or alkoxycarbonyl radical (with the proviso that R.sub.2 and R.sub.3 cannot simultaneously represent a hydrogen atom), the alanine moiety being in the L form, the glutamic acid moiety being in the D form, the lysine moiety (when R.sub.2 or R.sub.3 =a hydrogen atom) being in the L form and the 2,6-diaminopimelic acid moiety or its derivatives (when R.sub.2 and/or R.sub.3 =carboxy, carbamoyl or alkoxycarbonyl) being in the D,D, L,L, D,D/L,L (racemic) or D,L (meso) form, and salts thereof, possess immunological adjuvant and immunostimulant activity.
摘要:
Tetrapeptides and pentapeptides of the formula: ##STR1## wherein R represents hydrogen or a fatty acid residue, R.sub.1 represents hydroxy, amino, alkoxy of 1 to 4 carbon atoms, optionally substituted by phenyl or nitrophenyl, one of R.sub.2 and R.sub.4 represents hydrogen, carboxy, carbamoyl, alkoxycarbonyl of 2 to 5 carbon atoms, optionally substituted by phenyl or nitrophenyl, or a N-carbonylglycine or N-carbonyl-D-alanine radical optionally esterified by alkyl of 1 to 4 carbon atoms (which is optionally substituted by phenyl or nitrophenyl) and the other symbol represents hydrogen, carboxy, carbamoyl, or alkoxycarbonyl fof 2 to 5 carbon atoms, optionally substituted by phenyl or nitrophenyl, and R.sub.3 represents hydrogen, a fatty acid residue or a glycyl or D-alanyl moiety in which the amine group is optionally substituted by a fatty acid residue, it being understood that R.sub.2 and R.sub.4 cannot simutaneously represent hydrogen, that at least one of R.sub.2, R.sub.3 and R.sub.4 represents a glycyl or D-alanyl moiety, that at least one of R and R.sub.3 represents or contains a fatty acid residue, and that the alanine moiety is in the L form, the glutamic acid moiety or its derivatives are in the D form, the lysine moiety or its derivatives, when one of the symbols R.sub.2 and R.sub.4 represents a hydrogen atom, are in the L form, and the 2,6-diaminopimelic acid moiety or fits derivatives, when R.sub.2 and R.sub.4 represent a carboxy, carbamoyl or alkoxycarbonyl radical, are in the D,D L,L,D,D/L,L (racemic) or D,L (meso) form, and salts thereof possess immunostimulant activity.
摘要:
Improved precipitated silica particulates, well adapted as a pigment or reinforcing filler for curable organosilic polymers and other elastomers, have the properties:______________________________________ (i) BET surface area 190 to 340 m.sup.2 /g (ii) CTAB surface area 180 to 280 m.sup.2 /g (iii) ##STR1## 0.9 to 1.2 (iv) Residual sodium content
摘要:
A novel anhydrous sodium tripolyphosphate, well adapted as an additive for foodstuffs and detergent compositions, has an Na/P ratio of essentially 1.667.+-.0.01, an apparent density of from 0.5 to 1.1, a mean agglomerate size of less than 100 microns, a phase I content ranging from 15 to 6% by weight, is devoid of insoluble fraction, and displays zero solidification or caking in a quiescent solvent medium.
摘要:
A process for the manufacture of low molecular weight polyacrylic acids or their salts is provided, particularly, their aqueous solutions. Acrylic acid in an aqueous solution containing a polymerization initiator is polymerized in the presence of acetic acid and/or propionic acid.The solutions obtained have a low viscosity and are very stable on storage.
摘要:
SiO.sub.2 /MeO metallic silicates, wherein Me is lead or an alkaline earth metal, have a molar ratio of SiO.sub.2 to MeO of greater than 2, and same are well suited as pigments, fillers, and especially as glass-formers.
摘要:
The invention pertains to the field of packaging and to a coating composition composed of a polyvinyl alcohol solution and a polymer latex for imparting gas and flavor tight packaging.