Risk management in cryopreservation associated with assisted reproduction

The process of cryopreservation of cells and tissues either for research or for therapeutic use is loaded with risk from beginning to end. Centres must focus on key areas of potential hazard or incident, particularly those associated with injury, loss or damage to stored material, and misidentification of stored material. Incidents involving any would have more fundamental consequences for the laboratory including financial loss and a threat to continuation of a service or project. Control measures to prevent injury are as much about education in the use and handling of liquid nitrogen as they are about protective clothing and more attention should be focused on preventing explosion, asphyxiation, burns and injury from manual handling. Other major losses are focused on damage to samples due to inappropriate processing, inadvertent thaw or less likely, contamination from another sample or microorganism. Complete sample losses can result from misidentification, poor inventory control and poor record keeping with regard to the use of samples in therapeutic procedures. Control and prevention of these hazards may require significant resources, although more often than not involve simple changes in procedure, ensuring that equipment and materials are fit for purpose and that personnel are suitably trained. Identification of such risk relies on a combination of a systematic prospective approach (risk assessment) with a documented and formal recognition of previous mistakes or near misses. Risk potential can be formally scored and ranked to provide services with the means of prioritising and allocating appropriate resources. Failure to implement a comprehensive risk management strategy could be translated as 'negligence' should a similar incident subsequently occur. The risk management of any services including cryopreservation should therefore be considered fundamental and integrated into business planning, objective setting and departmental budgeting to ensure continued improvement and the delivery of a quality and safe service or indeed research project.     

The Prospect for O.R. in the Nigerian Government Service—An Administrators' Viewpoint

The paper reports the results of interviews with senior government administrators in Nigeria in which they were asked a range of questions about their own work and about the problems that are likely to be encountered in trying to introduce operational research into the government service. It is thus in contrast with most papers on O.R. in developing countries, which are written primarily from the viewpoint of practitioners. The administrators confirmed that there was a wide range of problems recognized as being suitable for the O.R. approach, and identified some of the barriers to the introduction of an effective O.R. service.     

Nature of the stable oxide layer formed on an aluminum surface by work function measurements

The interaction of oxygen with clean aluminum results in formation of a stable oxide layer on the surface of the metal. This stable layer has a lower work function than that of clean aluminum. The nature of this stable layer is studied by measurement of work function changes. Heating of the stable layer, formed at room temperature and low oxygen pressures' (~10^?8 torr), in ultra-high vacuum resulted in a further decrease in the work function. The extent of this additional decrease was a function of temperature and the changes in work function caused by heating were irreversible in nature. At high oxygen pressures (p_O2 > 10^?2 torr) the effect of growth of incorporated oxide on the net limiting work function change appears to be small and the reversible changes in the work function are mainly a result of the variation in the amount of surface oxide. At 250°C, the contribution of incorporated oxide to net limiting work function change was dependent on oxygen pressure when it was formed at low oxygen pressures (P < 10^?7 torr). However, when the incorporated oxide was formed at oxygen pressures above 10^?7 torr, its contribution to the limiting work function change and, perhaps, the structure of the incorporated oxide itself were nearly independent of oxygen pressure. The difference in limiting work function change at various oxygen pressures was mainly because of the difference in the limiting amounts of surface oxide. Similar behavior is expected at room temperature.     

The Stock Control of Engineering Spares—A Case Study

This paper discusses the experience of an operational research group in developing a practical scheme for the control of spares in an organization with many central and subsidiary stores. It covers the development of the scheme from the choice of the method of control to the publication of control tables for use throughout the organization; it is complementary to earlier papers on the methods of cost measurement and the mathematical analysis.Reasons are given for choosing a re-order level scheme rather than a cyclical review scheme, and for using run out costs rather than levels of service. The effect of errors in estimating physical and economic parameters is discussed; in practice not all the parameters need to be considered explicitly. Several modifications made to meet practical objections are described. The paper ends with some comments on possible future developments.     

Formation of surface-grafted copolymer brushes with continuous composition gradients

We report on a simple methodology that facilitates the generation of surface-grafted assemblies comprising block copolymers with tunable composition and molecular weight gradients along flat solid substrates.     

A rapid radiochemical method for antimony and arsenic : Development and testing of the method

The formation of stibine and arsine by flash electrolysis is applied to the rapid separation of radioactive isotopes of antimony and arsenic from a mixture of fission products. A chemical yield of 45% for both antimony and arsenic was achieved in 10 sec. The conditions necessary for the clean separation of antimony and arsenic from one another and from other fission products are described. The method proved successful both in the laboratory and in a nuclear reactor.