The effect of spent coffee ground (SCG) loading, matrix ratio and biological treatment of SCG on poly(hydroxybutyrate) (PHB)/poly(lactic acid) (PLA) polymer blend.

This study investigates the effects of SCG embedded into biodegradable polymer blends and aimed to formulate and characterise biomass-reinforced biocomposites using spent coffee ground (SCG) as reinforcement in PHB/PLA polymer blend. The effect of SCG filler loading and varying PHB/PLA ratios on the tensile properties and morphological characteristics of the biocomposites were examined. The results indicated that tensile properties reduction could be due to its incompatibility with the PHB/PLA matrixSCG aggregation at 40 wt% content resulted in higher void formation compared to lower content at 10 wt%. A PHB/PLA ratio of 50/50 with SCG loading 20 wt% was chosen for biocomposites with treated SCG. Biological treatment of SCG using Phanerochaete chrysosporium CK01 and Aspergillus niger DWA8 indicated P. chrysosporium CK01 necessitated a higher moisture content for optimum growth and enzyme production, whereas the optimal conditions for enzyme production (50-55 %, w/w) differed from those promoting A. niger DWA8 growth (40 %, w/w). SEM micrographs highlighted uniform distribution and effective wetting of treated SCG, resulting in improvements of tensile strength and modulus of biocomposites, respectively. The study demonstrated the effectiveness of sustainable fungal treatment in enhancing the interfacial adhesion between treated SCG and the PHB/PLA matrix.

Effect of experimental alterations in excess weight on aerobic capacity and distance running performance.

To experimentally investigate the effect of excess body weight or fat on maximal oxygen uptake (Vo2 max) and distance running performance, the metabolic response to maximal and submaximal treadmill running and the 12-min run performance were measured in six subjects under each of four added-weight (AW) conditions: normal body weight and 5, 10, and 15% additional external weight, added to the trunk. AW was found to systematically and significantly decrease Vo2 max expressed relative to the total weight carried (ml/min.dg TW), maximal treadmill (TM) run time and 12-min run distance, but not to systematically affect Vo2 max (1/min) or Vo2 max (ml/min.kg FFW). An increase of 5% AW was found, on the average, to decrease Vo2 max (ml/min.kg TW) 2.4 ml, the TM run time 35 sec and the 12-min run distance 89 m. These decreases were a direct consequence of the increased energy cost of running at submaximal speeds. It was concluded that changes in excess body weight can influence Vo2 max expressed relative to body weight and distance run performance independent of any change in cardiovascular capacity. Failure to distinguish the metabolic effects of body fatness from the influence of cardiorespiratory capacity may result in misleading interpretation of distance run test scores.