Myocardial oxygen consumption at rest and during submaximal exercise: effects of increased adiposity.

Overweight and obesity are major risk factors for cardiovascular diseases. The objective of this study was to determine the effect of increased adiposity on myocardial oxygen consumption at rest and during submaximal exercise in young adults. The study consisted of 85 young adults (18-22 years) grouped into 3 based on their body mass index as normal (NW, n=30), overweight (OW, n=25) and obese (OB, n=30). Steady dynamic exercise test equivalent to Grade 2 Bruce protocol was carried out on treadmill for 5min. Blood pressure and heart rate were recorded before, during 3rd min of exercise, immediately after cessation of exercise and during 5th min of recovery. MVO2 was measured by the Rate Pressure Product (RPP) calculated as product of heart rate and systolic blood pressure. Statistical analysis was done using ANOVA and regression analysis. The mean resting RPP was significantly higher in overweight and obese groups when compared with the normal weight group (p<0.05). There was significant increase in RPP changes to exercise [mean difference in NW-8270.93 bpm.mmHg (99.61%), OW-10593.12 bpm.mmHg (118.39%) and OB-10897.33 bpm.mmHg (118.10%), p< 0.05] and the value did not return to baseline after 5 mins of recovery in study groups (p< 0.05). BMI and Waist stature ratio were the most important independent parameters in prediction of RPP. The study shows that overweight and obese young adults have elevated resting RPP and much higher RPP response to exercise indicating increased (MVO2) at rest and during exercise suggesting higher hemodynamic stress to the heart.

Biosorption of nickel from aqueous solutions by Acacia leucocephala bark: Kinetics and equilibrium studies.

The biosorption of nickel(II) ions from aqueous solution by Acacia leucocephala bark was studied in a batch adsorption system as a function of pH, initial metal ion concentration, adsorbent dosage, contact time and temperature. The maximum Ni(II) adsorption was obtained at pH 5. Further, the biosorbents were characterized by Fourier Transformer Infrared Spectroscopy (FTIR). The experimental data were analysed using three sorption kinetic models viz., the pseudo-first- and second-order equations and the intraparticle diffusion model. Results show that the pseudo-second-order equation provides the best correlation for the biosorption process. The equilibrium nature of Ni(II) adsorption at different temperatures of 30, 40 and 50 degrees C have been described by the Langmuir and Freundlich isotherm models. The equilibrium data fit well Langmuir isotherm. The monolayer adsorption capacity of A. leucocephala bark as obtained from Langmuir isotherm at 30 degrees C was found to be 294.1mg/g. The Chi-square (chi(2)) and Sum of the square errors (SSE) tests were also carried out to find the best fit adsorption isotherm and kinetic model. Isotherms have been used to determine thermodynamic parameters of the process, viz., free energy change (DeltaG degrees), enthalpy change (DeltaH degrees), and entropy change (DeltaS degrees) were calculated indicating that this system was a spontaneous and endothermic process. Present investigation emphasized that A. leucocephala bark may be utilized as a low cost adsorbent for nickel removal.

Adsorptive removal of copper and nickel ions from water using chitosan coated PVC beads.

A new biosorbent was developed by coating chitosan, a naturally and abundantly available biopolymer, on to polyvinyl chloride (PVC) beads. The biosorbent was characterized by FTIR spectra, porosity and surface area analyses. Equilibrium and column flow adsorption characteristics of copper(II) and nickel(II) ions on the biosorbent were studied. The effect of pH, agitation time, concentration of adsorbate and amount of adsorbent on the extent of adsorption was investigated. The experimental data were fitted to Langmuir and Freundlich adsorption isotherms. The data were analyzed on the basis of Lagergren pseudo first order, pseudo-second order and Weber-Morris intraparticle diffusion models. The maximum monolayer adsorption capacity of chitosan coated PVC sorbent as obtained from Langmuir adsorption isotherm was found to be 87.9 mg g(-1) for Cu(II) and 120.5 mg g(-1) for Ni(II) ions, respectively. In addition, breakthrough curves were obtained from column flow experiments. The experimental results demonstrated that chitosan coated PVC beads could be used for the removal of Cu(II) and Ni(II) ions from aqueous medium through adsorption.