Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber.

Activated carbon fixed beds are classically used to remove volatile organic compounds (VOCs) present in gaseous emissions. In such use, an increase of local temperature due to exothermal adsorption has been reported; some accidental fires in the carbon bed due to the removal of high concentrations of ketones have been published. In this work, removal of VOCs was performed in a laboratory-scale pilot unit. In order to visualize the increase in local temperature, the adsorption front was tracked with a flame ionization detector and the thermal wave was simultaneously visualized with an infrared camera. In extreme conditions, fire in the adsorber and the combustion of activated carbon was achieved during ketone adsorption. Data have been extracted from these experiments, including local temperature, front velocity and carbon bed combustion conditions.

Omission after admission: failure in prescribed medications being given to inpatients.

Prescribing errors are a recognised problem on admission to acute medical wards which may be detrimental to patient care. The authors had anecdotal evidence that prescribed medicines do not always reach patients and the aim of this audit was to quantify this problem. Admission prescription charts on two separate occasions were studied in detail and all drugs prescribed but not given in the first 48 hours were recorded along with the reason given for omission. In total, 271 patient charts were analysed. Of these, 20% of prescriptions affecting 17% of patients did not reach patients. The two dominant reasons for medications not being given to patients were that the medication was not available on the ward (38% of omissions) or that the patient was nil by mouth (32% of omissions). In 10% of cases the patient refused the medication, in 19% no reason for omission was given and in only a minority (0.3%) was the patient off the ward. This audit demonstrates that even when medications are prescribed they are not always given. This may lead to increased morbidity and length of stay. Strategies need to be put in place to reduce this problem. The current system that permits omission of medications with inadequate justification must be revised.

A model to predict the adsorber thermal behavior during treatment of volatile organic compounds onto wet activated carbon.

A model for adsorption of volatile organic compounds (VOCs) onto a wet activated carbon bed was proposed in this study. This model accounts for temperature changes induced by the reversed and coupled mass-transfer processes of both organic species adsorption and water desorption. Indeed, it was experimentally pointed out that temperature rises, which result from the exothermal nature of the energetic interactions between the organic molecule and the activated carbon surface, are notably reduced when the adsorbent contains an initial moisture of approximately 10% in weight. Moreover, it was shown that water rate desorption was enhanced in the presence of organic vapor. This phenomenon may be explained by the displacement of sorbed water bythe organic molecules, owing to more intensive interactions with the activated carbon surface. The model proposed was elaborated from a previous comprehensive analysis of the diffusion mechanisms governing VOC adsorption at high concentrations onto a dry activated carbon bed. In a similar way, a theoretical approach was developed to model water desorption during drying of a wet activated carbon bed under pure flowing air. At last, a theoretical depiction of both competitive and reverse processes was outlined. The final model fits reasonably with experimental data relative to both breakthrough curves and thermal wave shape along the bed, even if local temperature change calculation may require some further improvement.

[The importance of periodontal evaluation in orthodontics]. / De l'importance de l'évaluation parodontale en orthodontie.

The orthodontist is in fact a periodontal-therapist since his aim is to move the teeth with and through the periodontal tissues. It is most important for the orthodontist to be able to determine at the initial clinical examination what are the various periodontal risk factors. When the pathology is obvious with inflammation, periodontal pockets, gingival hyperplasia, edema of the papillae, gingival recessions, the need for periodontal treatment is manifest. But many times, the periodontal evaluation is complicated by the presence of slight variations of the quality of the marginal tissue that represent a risk of developing periodontal defects during the orthodontic treatment. The aim of this presentation is to put forward the importance of the periodontal evaluation during the initial examination of the patient so that, if necessary, an adequate periodontal therapy can be initiated to stabilize the periodontal tissues and thus improves the esthetical outcome.