Diffusion scrubber technique used for measurements of atmospheric ammonia

A diffusion scrubber (DS) was developed to measure trace levels of gaseous ammonia in ambient air. The sampling resolution time for this method is 10 min and the detection limit is estimated to be 0.01 ppbv. The response to the NI-I₃ concentrations is found to be dependent on the relative humidity in the ambient air and the temperature. The method is calibrated by using a diluted NH₃ cylinder gas, and the concentrations of the calibration gas were in the range 0.02–2 ppbv during the test. Sampling performed with the DS-method is compared to sampling performed by a filter pack and a continuous flow denuder (AMANDA). The DS-method shows good agreement with the continuous flow denuder and the filter pack.     

Drei neue Nickelenzyme aus anaeroben Bakterien

Until recently nickel was not considered to be an element of biological importance. Nutritional studies have shown, however, that many eucaryotic and procaryotic organisms are dependent on the transition metal for growth. Four enzymes are presently known to contain nickel: urease from plants and from bacteria; methyl CoM reductase from methanogenic bacteria; all “uptake” hydrogenases investigated so far; and carbon monoxide dehydrogenase from anaerobic bacteria. The prosthetic group of the methyl CoM reductase has been identified as a nickel tetrapyrrole, the structure of which has been elucidated.     

Flexible Management System for Occupational Safety and Quality

Abstract

In the 10 analysed companies it is necessary to create a management for flexible processes and a structured flexibilisation of these processes. This represents the basis for the retention of existing flexibility and occupational safety.

The strategy for a management of flexible processes leads,

? firstly, to a structuring of company procedures whilst still retaining the necessary flexibility and certification ability as laid down by standards No. DIN EN ISO 9000ff. and,

? secondly, to the keeping of the demands of an occupational safety management system.

In this article the inclusion of co-workers stands in the foreground. This will be combined with the goal to utilise their experience and their acceptance of the solutions worked out.