Microbial anti-biofilms: types and mechanism of action

Biofilms have been recognized as a serious threat to public health as it protects microbes from antimicrobials, immune defence mechanisms, chemical treatments and nutritional stress. Biofilms are also a source of concern in industries and water treatment because their presence compromises the integrity of equipment. To overcome these problems, it is necessary to identify novel anti-biofilm compounds. Products of microorganisms have been identified as promising broad-spectrum anti-biofilm agents. These natural products include biosurfactants, antimicrobial peptides, enzymes and bioactive compounds. Anti-biofilm products of microbial origin are chemically diverse and possess a broad spectrum of activities against biofilms. The objective of this review is to give an overview of the different types of microbial anti-biofilm products and their mechanisms of action.

TECHNO-ECONOMIC INVESTIGATION OF DIFFERENT ALTERNATIVES OF IMPROVING SIMPLE GAS TURBINE INTEGRATION OPTIONS

This study investigated the effect of integrating various models proposed to improve a simple gas turbine power plant. A computer program was developed in Matlab software was used to simulate the performance parameters. The energy and exergy analysis of the plant was carried out. The energy and exergy analysis result revealed that both energy and exergy efficiency of plant is low as a result three improvement options were considered. They include Model 1: reducing inlet air cooling (IAC) of the compressor by using the wasted energy in the natural gas pressure drop station. Model 2: recovering wasted energy in the exhaust through heat recovery steam generator (HRSG) and injecting steam into the combustion chamber and lastly Model 3: by combining the two methods. The result showed that among the three methods of improving the plant investigated Model 3 was found to boost power output of the plant from 28.3 MW to 78.4 MW while the thermal and exergetic efficiency improved by 25.5 and 23.6% respectively. Furthermore, from economic and environmental point of view, the lowest levelized cost of electricity as well as the specific emissions was observed in Model 3. Consequently, Model 3 is selected as the best option in improving the simple gas turbine.  http://dx.doi.org/10.4314/njt.v36i3.27

Aerobic and anaerobic power characteristics of Saudi elite soccer players

BACKGROUND

To assess the aerobic and anaerobic characteristics of Saudi elite soccer players, and to examine the interrelationship between measures of aerobic and anaerobic power in the elite soccer players. METHODS.

PARTICIPANT

Twenty-three outfield elite soccer players representing the Saudi national team participated. Their means (+/- SD) for age, body mass, height and estimated fat % were: 25.2 +/- 2.3 years; 73.1 +/- 6.8 kg; 177.2 +/- 5.9 cm; and 12.3 +/- 2.7%, respectively.

MEASURES

Cardiorespiratory parameters, including maximal oxygen uptake (V O2 max), were assessed by open-circuit spirometry during graded treadmill running. Anaerobic power measures were obtained using Wingate anaerobic test, and included peak power (PP), and average power for 5 sec (AP 5), 10 sec (AP 10), 20 sec (AP 20) and 30 sec (AP 30).

RESULTS

Mean (+/-SD) values for V O2max in absolute and relative to body mass were 4.16 +/- 0.34 l x min-1 and 56.8 +/- 4.8 ml x kg-1 x min-1, respectively. Such V O2max value was 118% and 80% of those reported for Saudi college males and distance runners, respectively. The ventilatory anaerobic thereshold (Tvent) averaged 43.6 ml x kg-1 x min-1. There were no significant differences in V O2max and Tvent between players based on positions, although the midfielders and the centre-backs had the highest and the lowest individual values for both measures, respectively. Values (+/- SD) of PP and AP 30 were 873.6 +/- 141.8 W (11.88 +/- 1.3 W x kg-1), and 587.7 +/-55.4 W (8.02 +/- 0.53 W x kg-1), respectively. Only in absolute PP & AP 30 were the centre-backs significantly superior to the other players. In addition, V O2max was inversely related to PP (r = - 0.54; p < 0.05) and positively related to AP 30 (r = 0.45; p < 0.05).

CONCLUSIONS

The aerobic power, expressed relative to body mass, of Saudi elite soccer players was in the lower range of values normally reported in the literatures for elite soccer players. Both PP and AP 30 were somewhat lower than values previously reported for elite soccer players from other countries.

Cardiorespiratory fitness, physical activity patterns and coronary risk factors in preadolescent boys

The relationships between cardiorespiratory fitness, daily physical activity, and selected coronary artery disease (CAD) risk factors were evaluated in a sample of 91 preadolescent boys. Cardiorespiratory fitness was assessed (VO2max). Physical activity level was assessed using daytime heart rate telemetry. CAD risk factors included total cholesterol, fasting triglycerides, HDL-cholesterol, LDL-cholesterol, fasting blood glucose, systolic and diastolic blood pressures, and body fat content. The mean value of VO2max exhibited significant negative relationship with body fat percent (r = -0.55). Controlling the effects of age, body mass index and body fat percent resulted in a significant inverse relationship between physical activity and systolic (r = -0.29) and diastolic (r = -0.28) blood pressures. Analysis of data by quartiles revealed significant differences only in body fat percent across fitness categories, while no significant differences were detected in the other CAD risk factors. However, higher HDL-cholesterol and lower triglycerides levels were observed in those boys with higher levels of physical activity. It was concluded that except with body fatness, cardiorespiratory fitness is not strongly associated with lower CAD risk factors, while physical activity level was significantly associated with lower blood pressure level but not with the other CAD risk factors.