Oxidation of Hydrocarbons on the Surface of Tin Dioxide Chemical Sensors

The paper presents the results of our investigation on the effect of the molecular structure of organic vapors on the characteristics of resistive chemical gas sensors. The sensors were based on tin dioxide and prepared by means of thick film technology. The electrical and catalytic examinations showed that the abstraction of two hydrogen atoms from the organic molecule and formation of a water in result of reaction with a chemisorbed oxygen ion, determine the rate of oxidation reactions, and thus the sensor performance. The rate of the process depends on the order of carbon atoms and Lewis acidity of the molecule. Therefore, any modification of the surface centers of a sensor material, modifies not only the sensor sensitivity, but also its selectivity

A Study of the Influence of Nickel Chloride on the Physical Characteristics and Leachability of Portland Cement

STUDIES ON SOLIDIFICATION OF NICKEL CHLORIDE IN CEMENT PREPARED AT A WATER-TO-CEMENT RATIO REVEALED AN ACCELERATING EFFECT ON THE PHYSICAL CHARACTERISTICS OF THE MATRIX. A BEST COMPRESSIVE STRENGTH VALUE OF 21 MPA IS OBTAINED ON SAMPLE SPECIMEN OF CYLINDRICAL DIMENSIONS 35 MM H X 20 MM DIAM. WHEN ABOUT 8 WT% OF THE COMPOUND IS BLENDED IN CEMENT. THE LEACHING RESULTS ON NICKEL PRESENT AN EXTREMELY LOW CONSTANT CONCENTRATION OF 6.8X10-8 M/L IN LEACHATE MEDIA OF PH = 12.5, REVEALING A GOOD RETENTION CAPACITY OF CEMENT MATRIX. CHLORIDE ON THE OTHER HAND APPEARS TO HAVE ADVERSE EFFECTS ON MATRIX DURABILITY THROUGH ENHANCED LEACHABILITY OF CALCIUM CONTENTS.NA-NOT AVAILABL

Physical Properties Measurements and Leaching Behaviour of Chromium Compounds Solidified in a Cement Matrix

AS PART OF THE CHEMICAL NUCLEAR WASTE PROJECT, ENVIRONMENT PROGRAMME, LEACHING EXPERIMENTS ON CHROMIUM COMPOUNDS SOLIDIFIED IN CEMENT HAVE BEEN CARRIED OUT AQT THE CEC, JRC-ISPRA (ITALY). PHYSICAL TESTS HAVE BEEN CARRIED OUT ON CEMENT BLENDING VARIABLE AMOUNTS OF CHROMIUM COMPOUNDS. THE RESULTS CONCERNING THE COMPRESSIVE STRENGTH, DENSITIES AND POROSITY OF CEMENT CONTAINING CRCL3, CR2O3 AND CRO3 ARE REPORTED AND DISCUSSED.NA-NOT AVAILABL

Activity of the JRC EMEP Station. 1989 Annual Report

Abstract not availableNA-NOT AVAILABL

Evaluation of Cement Matrix Preparation and Leaching Procedures Used in Radioactive Waste Management

Abstract not availableNA-NOT AVAILABL

Influence of Chloride Admixtures on Cement Matrix Durability

Abstract not availableNA-NOT AVAILABL