Toxicity reduction and biodegradability enhancement of cork processing wastewaters by ozonation.

Biodegradability enhancement and detoxification of cork boiling wastewater (CBW) are required for the successful implementation of biological treatment options. We studied the possibility of achieving these goals through ozonation pre-treatment by experimenting on the effect of ozone dose and pH. The CBW used had a pH of 5.81, a chemical oxygen demand (COD) of 1,865 mg L(-1), a biochemical oxygen demand (BOD5) of 498 mg L(-1) and total phenol (TP) and tannin compounds concentrations of 523 and 399 mg L(-1), respectively. The ozone doses ranged from 0.27 to 2.63 for the O3(applied)/COD0 ratios with samples at natural pH and set to 3.33 and 9.96. Ozonation allowed the BOD20/COD ratio (biodegradability index) to increase from 0.37 to 0.63 and a toxicity reduction from 3.08 to 1.24 TU (Microtox). The corresponding removals obtained were 15.2-62.0%, 38.4-83.2% and 56.7-92.1% for COD, TP and colour, respectively. The best outcome of ozonation pre-treatment requires O3(applied)/COD0 ratios over 1.5 and an acid pH. The increase of TP removals with ozone dose at acid pH led to biodegradability enhancement and CBW detoxification. However, for similar conditions the highest COD removals were obtained at alkaline pH due to the hydroxyl radicals' high oxidation ability but lack of selectivity.

Global and partial synchronism in phase-locked loop networks.

We analytically investigate the existence of global and partial synchronism in neural networks where each node is represented by a phase oscillator. Partial synchronism, which is important to pattern recognition, can be caused by increasing the natural frequency of an oscillator and restricting the frequencies of others in certain ranges.

Infection by CagA-positive Helicobacter pylori strains in patients with ischemic heart disease: prevalence and association with exercise-induced electrocardiographic abnormalities.

The role of H. pylori infection in increasing the risk of ischemic heart diseases (IHD) is still debated. We determined serologically the prevalence of overall H. pylori and CagA-positive H. pylori infection in 63 consecutive patients with IHD and 189 gender- and age-matched controls. We also determined in patients the influence of the infection and the CagA serological status on the results of an exercise ECG test and other parameters considered possible variables that may enhance the risk of IHD. The prevalence of H. pylori infection in patients and controls was 79.3% and 73.0%, respectively (P = 0.403) and that of CagA-positive H. pylori infection was 69.8% and 42.3%, respectively (P = 0.0002). The scores of the ECG S-T segment and T-wave abnormalities in the course of an exercise ECG in uninfected patients and in patients infected by CagA-negative and CagA-positive H. pylori strains were (mean +/- SD): 1.59 +/- 0.67, 1.92 +/- 0.64, and 2.19 +/- 0.70, respectively; (P = 0.011, 95% confidence limits of difference 0.15-1.07, CagA-positive infected vs uninfected patients). There was no intergroup difference in the levels of peripheral white blood cells, glucose, cholesterol, triglycerides, creatinine, and systolic and diastolic pressure. In conclusion, genetic heterogeneity of H. pylori could possibly explain some conflicting results concerning the association of H. pylori infection with IHD. Coronary vessels of IHD patients infected by CagA-positive H. pylori strains may be damaged more severely than those of uninfected patients.