• Effect of seasonal programming on fetal development and longevity: links with environmental temperature.

      Flouris, Andreas D; Spiropoulos, Yiannis; Sakellariou, Giorgos J.; Koutedakis, Yiannis (Wiley, 2009)
      This study examined the effect of birth season on fetal development and longevity using two independent databases of all Greek citizens that were born (total: 516,874) or died (total: 554,101) between 1999 and 2003. We found significantly increased birth weight, gestational age, and longevity in individuals born during the autumn and winter seasons of the year. These individuals also demonstrated statistically significantly lower prevalence rates for fetal growth restriction and premature birth. Furthermore, we found that increased temperature at birth was associated with adverse effects on fetal development and longevity. In conclusion, our results show strong effects of season of birth on fetal development and longevity mediated, at least in part, by environmental temperature at time of birth.
    • Influence of high-temperature and low-humidity curing on chloride penetration in blended cement concrete

      Khatib, Jamal M.; Mangat, P.S. (Elsevier, 2002)
      The influence of high-temperature and low-humidity curing on chloride penetration in concrete containing cement replacement materials was investigated. Three different mixes were studied: a control mix in which no cement replacement materials were added and two mixes where cement was partially replaced by 20% fly ash and 9% silica fume (by weight), respectively, at a constant water-to-binder ratio of 0.45. High-temperature curing was employed to simulate concrete temperature in hot climate. The results show that at early periods of exposure, initial curing has a substantial influence on chloride penetration in concrete. The effect of initial curing is much reduced after a long period of exposure. The chloride penetration at early ages of exposure is directly related to the porosity of the binder phase and the absorption of concrete. Higher chloride penetration resistance was observed when cement is partially replaced with either fly ash or silica fume.
    • Survival of Escherichia coli O157:H7 in traditional African yoghurt fermentation.

      Ogwaro, B.A.; Gibson, Hazel; Whitehead, Michael P.; Hill, David J. (Elsevier Science Direct, 2002)
      Growth and survival of a nontoxigenic strain of Escherichia coli O157:H7 (ATCC 43888) was determined in traditionally fermented pasteurized milk. Preheated milk was inoculated with 1% (v/v) of a mixed culture of Lactobacillus delbrueckii ssp. bulgaricus (NCIMB 11778) and Streptococcus salivarius ssp. thermophilus (NCIMB 110368) and incubated at 25, 30, 37 or 43 degrees C for 24 h. E. coli O157:H7 (10(5) CFU/ml) were introduced into the milk pre- and post-fermentation. Fermented milk samples were subsequently stored at either 4 degrees C (refrigerator temperature) or 25 degrees C (to mimic African ambient temperature) for 5 days. After 24 h of fermentation, the pH of the samples fermented at the higher temperatures of 37-43 degrees C decreased from 6.8 to 4.4-4.0 ( +/- 0.2) whereas at the lower temperature of 25 degrees C, the pH decreased to pH 5.0 +/- 0.1. During this period, viable counts for E. coli O157:H7 increased from 10(5) to 10(8) - 10(9) CFU/ml except in milk fermented at 43 degrees C wherein viability declined to 10(4) CFU/ml. In fermented (25-30 degrees C) milk stored at 4 degrees C for 5 days, E. coli O157:H7 viability decreased from 10(8-9) to 10(6-7) CFU/ml whereas milk fermented at 43 degrees C resulted in loss of detectable cells. In contrast, storage of fermented milk samples at 25 degrees C for 5 days eventually resulted in complete loss of viability irrespective of fermentation temperature. Stationary phase E. coli O157:H7 inoculated post-fermentation (25 and 43 degrees C) survived during 4 degrees C storage, but not 25 degrees C storage. Fermentation temperature and subsequent storage temperature are critical to the growth and survival of E. coli O157:H7 in traditional fermented products involving yoghurt starter cultures.
    • Variations of PV module parameters with irradiance and temperature

      Ibrahim, H; Anani, Nader (Elsevier, 2017-10-23)
      © 2017 The Authors. Published by Elsevier Ltd. This paper presents a comparison of common and well-documented methods for varying the single-diode model parameters extracted at standard test conditions (STC) of a PV module to suit varying operating conditions of irradiance and temperature. To perform such a comparison, accurate values of the single-diode parameters at STC are required. These were obtained using well-established numerical and iterative methods. The Newton-Raphson method was found to be most accurate for obtaining these parameters at STC. Consequently, these parameters were used to compare the methods of varying the single-diode model parameters with temperature and irradiance. MATLAB software has been developed to evaluate the performance of each method using the Shell SQ150 PV module. Results are compared with measured data and discussion of the accuracy of various methods is presented. .