Municipal solid waste stabilisation by leachate recirculation

The purpose of this study is to determine the impact of leachate recirculation on stabilisation of municipal solid wastes. The study was carried out by using two lab-scale landfill bioreactors containing approximately 10 kg of waste each, in order to follow waste degradation over 16 weeks of time period. The main difference between anaerobic recirculated and without recirculation bioreactors options is determined in leachate quality. Leachate quality is regularly measured by the means of pH, electrical conductivity, calcium, magnesium, total kjeldahl nitrogen, phosphate and chemical oxygen demand (COD). It has been observed that leachate recirculation is more effective on anaerobic degradation of solid waste than non-recirculated degradation. The leachate recirculated bioreactor appears to be the more effective option in the removal of COD by 89.93% and stabilisation of pH at 7.5. After 16 weeks of anaerobic degradation, waste stabilization seemed to have reached for the recirculated bioreactor. Therefore, further studies are required to determine the optimum operational conditions for leachate recirculation rates, also with the operational costs of recirculation for solid waste stabilisation.

Acute spinal cord injury in pregnancy: an illustrative case and literature review

Acute trauma is not all that uncommon in pregnancy. It accounts for 15% of non-obstetric maternal deaths. Moreover, about 15% of acute spinal cord injuries involve young women of childbearing age (Gilson et al., 1995). Most of the existing literature on spinal cord injury in pregnancy is concerned with the management of patients with pre-existing lesions; very few articles deal with acute injuries. We report the management of a case of acute spinal cord injury in the third trimester of pregnancy and review the major clinical issues associated with such cases.

First principles based design and experimental evidence for a ZnO-based ferromagnet at room temperature

The introduction of ferromagnetic order in ZnO results in a transparent piezoelectric ferromagnet and further expands its already wide range of applications into the emerging field of spintronics. Through an analysis of density functional calculations we determine the nature of magnetic interactions for transition metals doped ZnO and develop a physical picture based on hybridization, superexchange, and double exchange that captures chemical trends. We identify a crucial role of defects in the observed weak and preparation sensitive ferromagnetism in ZnO:Mn and ZnO:Co. We predict and explain co-doping of Li and Zn interstitials to both yield ferromagnetism in ZnO:Co, in contrast with earlier insights, and verify it experimentally.

Epidural compared with general anaesthesia for caesarean delivery in conscious women with eclampsia

OBJECTIVE

To compare retrospectively the outcome of caesarean section under epidural anaesthesia with that of general anaesthesia in "stable" women with eclampsia.

DESIGN

Retrospective review.

METHOD

Over the five-year study period, there were 533 women with eclampsia and of these 66 women (12.4%), fulfilled the criteria of being 'stable'. Of the 66 women, 37 received epidural, 27 general, and 2 spinal anaesthesia.

RESULTS

There were no major complications with either general or epidural anaesthesia. Epidural anaesthesia was associated with higher one-minute Apgar scores.

CONCLUSION

This study indicates that both maternal and neonatal outcomes are not affected adversely by the use of epidural anaesthesia in selected cases of eclampsia.

Can pulse oximetry detect raised intracompartmental pressure?

Pulse oximetry has been advocated as a simple noninvasive investigation of vascular compromise. Its usefulness in aiding diagnosis of microvascular compromise in a developing compartment syndrome is questioned. This study investigates the reproducibility of pulse oximetry and the effect on arterial haemoglobin saturation of raising limb intracompartmental pressure by compression bandaging. In 32 out of 50 normal subjects there was a difference in percentage saturation between right and left arms, with a 2% difference in 6 people (12%). Percentage saturation fell significantly at average bandage pressures of 80 mmHg (P < 0.0001) and 60 mmHg (P < 0.001). At clinically relevant pressures, the test had a sensitivity of 40.4%. With a greater than 50% risk of a false-negative result, pulse oximetry is not an appropriate additional investigation in the detection of raised intracompartmental pressure.

Expectant management of early onset of severe pre-eclampsia in Durban

Fifty patients with severe pre-eclampsia who presented before 32 weeks' gestation were managed conservatively (sedation, bed rest, antihypertensive therapy and intensive fetal and maternal monitoring) until intervention was indicated. Twelve patients presented before 26 weeks of pregnancy and there were no fetal survivors in this group; 23 presented between 26 and 29 weeks and 8(34,8%) of the babies in this group survived. The rate of perinatal loss in those presenting between 30 and 32 weeks was 26,6% (N = 4). Patients who had a history of a hypertensive disorder in their previous pregnancy(ies) had a higher perinatal mortality rate; 23 such mothers experienced 16 perinatal losses compared with 27 mothers who had no such history and who had only 8 perinatal losses. There was 1 maternal death, there were 2 cases of eclampsia, 3 of pulmonary oedema, 4 of abruptio placentae and 1 case of renal failure; 2 patients had disseminated intravascular coagulation. The local indigent and underprivileged black population have a more aggressive form of early onset of severe pre-eclampsia than that reported for other population groups. The high maternal complication rate of 30,8% and the low fetal survival rate before 26 weeks indicate that there is no place in our setting for expectant management of severe pre-eclampsia in patients presenting before 26 weeks. This applies particularly to those with a previous history of hypertension in pregnancy.

Influence of preoperative gastric aspiration on the volume and pH of gastric contents in obstetric patients undergoing caesarean section

Aspiration of gastric contents, the most common anaesthetic cause of maternal mortality, is decreased by emptying of the stomach and the use of antacids and H2-receptor antagonists. One hundred and eighty-three mothers presenting for emergency Cesarean section were allocated to three groups. In group 1, the stomach was emptied before operation via an orogastric tube and thereafter 30 ml of sodium citrate 0.3 mol litre-1 was ingested 5-15 min before induction of general anaesthesia (our usual practice). Group 2 received only 30 ml of sodium citrate 0.3 mol litre-1. Group 3 received ranitidine 50 mg i.v. before operation, 5-15 min before induction of anaesthesia, in addition to sodium citrate. Our results show that preoperative gastric emptying with an orogastric tube followed by sodium citrate is preferred if anaesthesia should be induced 15-20 min later. However, the use of ranitidine and sodium citrate is preferred at subsequent times. Although our data show that preoperative gastric emptying decreased the mean intragastric volumes before Caesarean section, the number of patients at risk of acid aspiration was not reduced. In view of these findings and the unpleasantness of orogastric intubation, we suggest that routine preoperative gastric aspiration via an orogastric tube is not justified, although the manoeuvre should still be used following a recent meal.