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This work proposes a Mixed Integer Nonlinear Programming (MINLP) model to determine the optimal design of macroalgae based chemicals production plants. The superstructure considers two brown marine macroalgae species (Macrocystis pyrifera and Lessonia vadosa) that are used to produce sorbitol for further transformation. Two additional alternatives are included: corn starch as the traditional feedstock to obtain the corresponding sugars and directly buying sorbitol from market. Sorbitol is transformed into isosorbide, a platform molecule, which can be converted into a drug for heart disease (isosorbide dinitrate), a flame retardant, a biopolymer and a biosolvent (dimethyl isosorbide). The Renewable Process Synthesis Index Metric (RePSIM) is used as objective function to address sustainability. Alternatively, Net Present Value (NPV) is also considered to obtain a detailed economic analysis. In terms of sustainability, the production of isosorbide dinitrate is the optimal pathway, albeit it shows a negative RePSIM of −4.30 million USD/yr. On the other hand, the production of dimethyl isosorbide is the optimal configuration taking into account the economic objective function. Its NPV is 44.31 million USD with a production cost of 6.97 USD/kg. It is worth mentioning that the social and environmental aspect of the dimethyl isosorbide production process is positive. In this sense, this chemical can be obtained from marine macroalgae biomass in a profitable way with a process that is socially and environmentally beneficial.

The purposes of this study were to compare the patterns of the work rate (WR)-Vo2 and WR-heart rate (HR) relationships in incremental cycling, to ascertain the occurrence of a Vo2 deflection (Vo2def) coinciding with the HR deflection point (HRdef ), and to determine whether the Vo2def, if present, coincides with the ventilatory anaerobic threshold (VT). Twenty-four professional cyclists performed a maximal incremental test on a wind-load cycle ergometer. Work rate, HR, Vo2, and Vco2 were recorded. The WR-Vo2 relationships obtained were linear up to submaximal WR and curvilinear thereafter and thus described a Vo2def. The WR and Vo2 at Vo2def were mathematically determined for all subjects. The ratio of DeltaWR.DeltaVo2 up to Vo2def was significantly lower than that above Vo2def (90 +/- 11 W.L.min versus 133 +/- 35 W.L.min, p < 0.0001). The WR-HR relationships obtained were linear up to submaximal WR and curvilinear thereafter. The WR and HR at HRdef were mathematically determined for all subjects. The WR values at Vo2def and at HRdef (329 +/- 32 W and 326 +/- 34 W) were significantly correlated (R = 0.96, p < 0.0001) and in good concordance (limits of agreement from -4.7% to 3.2%, Bland-Altman analysis). The Vo2 at VT was then determined for all subjects. The Vo2 values at Vo2def and at VT were significantly correlated (R = 0.99, p < 0.0001) and in strong concordance (limits of agreement from -1.9% to 1.0%, Bland-Altman analysis). In conclusion, a Vo2def coinciding with HRdef and VT was shown. This confirms that the determination of the WR-HR relationship and of HRdef is a practical and noninvasive means of identifying anaerobic threshold.

Erythrocitary and serum magnesium (Mg) were determined in a group of 11 well-trained athletes before and after a 25-km running race, and in a group of 30 sedentary controls. The significant increase of mean erythrocitary Mg (EMg) concentration observed in the athletes after physical strain (2.58 +/- 0.34 mEq/l before, 3.10 +/- 0.45 mEq/l after the race: significance level = 5%) leads to the assumption that the possible Mg uptake is effected by the red blood cell to enhance some enzymatic reactions. The decrease of mean serum Mg concentration observed in the same subjects after the effort (1.70 +/- 0.14 mEq/l before, 1.64 +/- 0.15 mEq/l after the race) is not significant. The difference between mean Mg concentrations observed in the athletes' group before the race and in the sedentary group (EMg: 2.58 +/- 0.34 mEq/l in athletes, 3.67 +/- 0.38 mEq/l in sedentaries, significance level = 1%; serum Mg: 1.70 +/- 0.14 mEq/l in athletes, 1.96 +/- 0.15 mEq/l in sedentaries, significance level = 1%) suggests that athletes suffer from a Mg deficiency, partially due to physical exercise. The two hypotheses and the possible causes of the observed phenomena are discussed.

The relationship between velocity (V) and heart rate (HR) was determined in four canoeists, 42 cross-country skiers, 73 cyclists, nine ice-skaters, 10 roller-skaters, 32 rowers, and 20 walkers. The athletes were asked to increase their work intensity progressively, from low to submaximal velocities; HRs were determined by ECG in roller-, ice-skating, and walking, or read on a cardiofrequency meter in canoeing, cross-country skiing, cycling, and rowing. In all the athletes examined the linearity of the V-HR relationship was maintained up to a submaximal speed (deflection velocity, Vd), beyond which the increase in work intensity exceeded the increase in HR. Vd and anaerobic threshold (AT), determined through blood lactate measurements, were coincident in 19 athletes (6 cross-country skiers, 3 cyclists, 2 roller-skaters, 3 rowers, and 5 walkers). Vd was correlated with the average speeds maintained in walking (20 km, n = 13, r = 0.88), cross-country skiing (15 km, n = 20, r = 0.80; 30 km, n = 8, r = 0.82; 12 km, n = 7, r = 0.86; 11 km, n = 7, r = 0.86) and cycling (1,000 m flying-start, n = 68, r = 0.83), thus showing that AT is a limiting factor in these aerobic events.

The effect of a low-dose treatment (10 mg/day) of stanozolol on the anaerobic threshold (AT) and on maximal velocity (Vmax) was studied in ten well-trained runners in a 6-week trial experiment. The serum levels of testosterone (T), interstitial cell-stimulating hormone (ICSH), and of follicle-stimulating hormone (FSH) were determined before, during, and after the steroid administration. No improvements of AT and Vmax were found. No improvement of the competition running times was observed during the experimental period. The ICSH and FSH serum concentrations did not change significantly, while a marked decrease of the T serum concentration was observed. It is concluded that a low-dose treatment of stanozolol, sufficient to depress the testicular function, does not improve athletic performance.

Hematological variables of 40 professional cyclists, all receiving intravenous iron supplementation, were followed during a 15-month period. Mean values for red blood cells (RBC), hemoglobin (Hb), and hematocrit (Ht) were significantly lower during the racing season (RS) than during the nonracing periods (NRP) (RBC: RS = 4.53 +/- 0.34 millions/mm3, NRP = 5.09 +/- 0.36 millions/mm3; line 7 of abstract: Hb: RS = 14.2 +/- 0.9 g/dl, MRS = 15.2 +/- 0.9 g/dl; Ht: RS = 40.7 +/- 2.7% NRP = 44.4 +/- 2.9%; P less than 0.001 for all). However, mean values for ferritin and mean corpuscular hemoglobin (MCH) were significantly higher during the racing season (ferritin: RS = 422 +/- 398 ng/ml, NRP = 311 +/- 321 ng/ml, P less than 0.05; MCH: RS = 31.5 +/- 1.3 pg, NRP = 30.0 +/- 1.4 pg; P less than 0.001). These results suggest that the reductions in RBC, Hb, and Ht found in professional cyclists during the racing season are not the consequence of a diminution of iron stores but rather of reduced erythropoiesis and increased RBC destruction.

Serum erythropoietin (Epo) activity, hemoglobin (Hb), and hematocrit (Ht) were determined in 21 cross-country skiers during the training season. The Epo levels were not significantly reduced in the skiers relative to the normal population (P less than 0.01 and P less than 0.001, respectively). In 11 athletes Epo, Ht, urinary gamma-glutamyltransferase, N-acetyl-beta-glucosaminidase, and microalbuminuria were determined before and after a 50-km ski race at 1600 m above sea level. A significant increase of these variables (except for Ht) was found after the competition (P less than 0.001). It is concluded that while the reductions in Hb and Ht, which are typical of several endurance exercises, are not accompanied by a renal hypoxia sufficient to stimulate Epo overproduction, the renal hypoxia reached during the strenuous exercise of the race at altitude may be effective in determining blood increases in Epo.

Red blood cell indices, serum iron, and serum ferritin concentration were determined in 45 marathon runners, 56 ultramarathon runners, and 32 healthy sedentary controls. A significant reduction of hemoglobin concentration, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, serum iron, and serum ferritin were found in marathon runners compared to control subjects. The same variables were also reduced, but to a lesser extent, in the less trained ultramarathon runners. The decreased hemoglobin concentration demonstrated in the runners examined is related to both a reduced mean corpuscular hemoglobin concentration and a reduced hematocrit and may depend on a reduction of the body iron stores.

Recombinant human erythropoietin (EPO), commercially available since 1988, is thought to be used by athletes in aerobic sports for the purpose of increasing oxygen transport and aerobic power. In an attempt to identify EPO administration, we have studied the peripheral blood of 20 subjects practising sports at an amateur level. Automated cytometry was performed on the blood samples before and during 45 days of EPO treatment. The same hematological indices were determined for a control population that consisted of 240 elite athletes from various sports. As expected following EPO treatment, RBC, [Hb] and Hct increased significantly (increments of 8%, 6.3% and 11%, respectively). A significant increase in reticulocyte count was also observed. In addition, automated erythrocyte analysis showed a significant increase in cells with a volume > 120 fl and hemoglobin content (HC)