Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

The integrated chemical-biological degradation combining advanced oxidation by UV/H2O2 followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H2O2/L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required. (c) 2006 Elsevier B.V. All rights reserved.

Application of central composite rotatable design to modelling the effect of some operating variables on the performance of the three-product cyclone

The central composite rotatable design (CCRD) was used to design an experimental program to model the effects of inlet pressure, feed density, and length and diameter of the inner vortex finder on the operational performance of a 150-min three-product cyclone. The ranges of values of the variables used in the design were: inlet pressure: 80-130 kPa, feed density: 30 60%; length of IVF below the OVF: 50-585 mm; diameter of IVF: 35-50 mm. A total of 30 tests were conducted, which is 51 less; an that required for a three-level full factorial design. Because the model allows confident performance prediction by interpolation over the range of data in the database, it was used to construct response surface graphs to describe the effects of the variables on the performance of the three-product cyclone. To obtain a simple and yet a realistic model, it was refitted using only the variable terms that are significant at greater than or equal to 90% confidence level. Considering the selected operating variables, the resultant model is significant and predicts the experimental data well. (c) 2005 Elsevier B.V. All rights reserved.

Intra-abdominal pressure response to multidirectional support-surface translation

A complex response of the trunk muscles occurs to restore equilibrium in response to movement of the support surface. Intra-abdominal pressure (IAP) is considered to contribute to control of the trunk. This study investigated the contribution of IAP to the postural response to multidirection support-surface translation. IAP was recorded with a thin-film pressure transducer inserted via the nose into the stomach and trunk motion was recorded with an optoelectronic system with markers over the spinous process of L1. A pattern of trunk movement was recorded in response to the support-surface translations that was consistent with a 'hip' strategy of postural control. The trunk moved in a manner appropriate to move the centre of gravity over the new base of support. IAP was increased with movement in each direction, but varied in timing and amplitude between translation directions. In general, the IAP was greater with translations in the sagittal plane compared to the frontal plane and was initiated earlier for translations in the backward direction. These data indicate that IAP contributes to the postural response associated with support-surface translation and suggest that this is consistent with stiffening the spine. (C) 2003 Elsevier B.V. All rights reserved.

Quadriceps activity and movement reactions in response to unpredictable sagittal support-surface translations in women with patellofemoral pain

Patellofemoral pain (PFP) may be related to unfavorable knee joint loading. Delayed and/or reduced activity of vastus medialis obliquus (VMO) and different movement patterns have been identified in individuals with PFP in some studies, whereas other studies have failed to show a difference compared to non-affected controls. The discrepancy between study results may depend on the different tasks that have been investigated. No previous study has investigated these variables in postural responses to unpredictable perturbations in PFP. Whole body three dimensional kinematics and surface EMG of quadriceps muscles activation was studied in postural responses to unpredictable support surface translations in 17 women with PFP who were pain free at the time of testing, and 17 matched healthy controls. The results of the present study showed earlier onset of VMO activity and associated changes in kinematics to anterior platform translation in the PFP subjects. We suggest that the relative timing between the portions quadriceps muscles may be task specific and part of an adapted response in attempt to reduce knee joint loading. This learned response appears to remain even when the pain is no longer present.