Electroreduction of oxygen on octadecylmercaptan self-assembled monolayers.

The reduction of oxygen has been studied on octadecylmercaptan self-assembled monolayers adsorbed on gold substrates in borate buffer solutions with a rotating disc electrode. A great inhibition of the oxygen reduction and other electrochemical reactions by these monolayers has been found. However, after polarisation at -0.80 V(SHE) the protecting properties of the film against electron transfer reactions are lost, and a behaviour similar to bare gold is observed. Ex situ XPS indicates that the thiol monolayer has not been desorbed to a large extent during oxygen reduction. Disorders of the monolayer structure and desorption of thiol molecules are proposed as the main reasons for the accessibility of electrochemical reactions to the surface.

Adsorption of self-assembled monolayers of mercaptan on gold.

XPS and AES are suitable techniques for studying organic monolayers on metals if radiation doses are kept low. The adsorption of self-assembled (SA) mercaptan monolayers on gold is a process in two stages. The adsorption to near completeness is very rapid. However, the process of orientation of the carbon chains, which is responsible for the blocking of electrochemical reactions takes much longer, as could be shown by ARXPS (angle resolved X-ray photo electron spectroscopy). Adsorption under potential control allows electrochemical experiments during the adsorption process as e.g. the measurement of the capacity of the electric double layer. Furthermore the control of the potential guarantees sure that the metal/liquid interface is well defined during the adsorption process.

[The role of thoracic radiography in the intensive care unit of a department of internal medicine]. / Helyszíni mellkasfelvételek alkalmazása belgyógyászati intenzív osztályon.

Authors review the main principles of chest X-ray examination methodology and analyse their one-year material. During this time 225 chest X-ray films were taken by means of a mobile X-ray unit. The majority of patients were treated for cardiac disorders (e.g. AMI). Authors analyse the distribution of patients according to their illnesses, the correlation between the clinical and the radiological diagnoses and the quality of the X-ray films. Authors emphasize the importance of the correct collaboration between the staff of the intensive care unit and the radiological department.

Precision low cost V block for heavy loads.

A new type of V block is described. It is constructed from separate elements and is suitable for use with heavy loads. Its accuracy is the same as conventional monolithic V blocks while its cost is much lower than that of commercial precision V blocks.