Abstract: The invention relates to a gliding element with a substrate and a diamond layer formed on a surface of the substrate with an average maximum roughness value Rz. To improve the dry running properties the invention suggests that the diamond layer has reproducible recesses for the collection of abrasion, wherein a depth of the recesses is greater than the average maximum roughness value Rz.

Abstract: A process for the preparation of 2-hydroxynaphthalene-6-carboxylic acid using potassium carbonate and CO at temperatures above 260.degree. C. and at a pressure of at least 10 bar comprises using 2-hydroxynaphthalene-3-carboxylic acid and/or 2-hydroxynaphthalene-3,6-dicarboxylic acid and/or their potassium salts and, if desired, potassium .beta.-naphtholate as starting materials.The process according to the invention enables a considerable increase, by reusing the secondary products, in the product selectivity with regard to 2-hydroxy-naphthalene-6-carboxylic acid.

Abstract: A process for the preparation of aromatic hydroxy carboxylic acids by reacting alkali metal phenolates or alkali metal naphtholates with alkali metal carbonates and carbon monoxide, with subsequent acidification, wherein the solid starting materials--alkali metal carbonate and/or alkali metal phenolate or naphtholate--are metered into the reaction mixture in the form of one or more dispersions in an inert organic liquid.The process according to the invention enables the preparation of aromatic hydroxy carboxylic acids in good yields and with high chemical selectivity. Additional measures for increasing the selectivity, as described for example for the Kolbe-Schmitt reaction in EP-A 0 053 824, EP-A 0 081 753 and EP-A 0 254 596, and for the reaction with CO and carbonate in, for example, WO 91/11422, are unnecessary.

Abstract: A process for preparing aromatic hydroxycarboxylic acids or di-salts thereof by reaction of alkali metal phenolates or naphtholates with carbon dioxide, in the presence or absence of a further alkali metal salt, which comprises introducing the solid phenolate or naphtholate starting materials and, if desired, the alkali metal salt into the reaction mixture batchwise or continuously, separately or together, in the form of a dispersion in an inert organic liquid.The process of the invention makes possible the preparation of aromatic hydroxycarboxylic acids in good yields and with high chemical selectivity. Additional measures for increasing the selectivity, as are described for the Kolbe-Schmitt reaction in, for example, EP-A 0 053 824, EP-A 0 081 753 and EP-A 0 254 596, can be omitted.