Optimization of biohydrogen production by Clostridium butyricum EB6 from palm oil mill effluent using response surface methodology

Clostridium butyricum EB6 successfully produced hydrogen gas from palm oil mill effluent (POME). In this study, central composite design and response surface methodology were applied to determine the optimum conditions for hydrogen production (P_c) and maximum hydrogen production rate (R_max) from POME. Experimental results showed that the pH, temperature and chemical oxygen demand (COD) of POME affected both the hydrogen production and production rate, both individually and interactively. The optimum conditions for hydrogen production (P_c) were pH 5.69, 36 °C, and 92 g COD/l; with an estimated P_c value of 306 ml H₂/g carbohydrate. The optimum conditions for maximum hydrogen production rate (R_max) were pH 6.52, 41 °C and 60 g COD/l; with an estimated R_max value of 914 ml H₂/h. An overlay study was performed to obtain an overall model optimization. The optimized conditions for the overall model were pH 6.05, 36 °C and 94 g COD/l. The hydrogen content in the biogas produced ranged from 60% to 75%.     

Will energy regulations in the Gulf States make buildings more comfortable – A scoping study of residential buildings

Building envelope impacts upon energy consumption and indoor environment. The relationship between envelope components and indoor environment has become increasingly important, especially with the new emphasis on visual comfort, thermal comfort and indoor air quality. This paper examines the interaction between occupant thermal comfort and envelope component regulations in the Gulf States. The country chosen for this study is the Kingdom of Bahrain, the smallest country in the Gulf region. Simulation results and comparative studies were employed to investigate the impact of the current envelope component regulations on the internal environment. The paper focuses on residential buildings and concludes that the envelope component regulations contribute positively to the internal thermal performance. Although these envelope components are not generally the primary elements that impact upon internal thermal comfort there are circumstances when the components become very warm and occupants positioned close to them will experience discomfort. This paper shows that the thermal insulation regulation makes a small impact on thermal comfort, whereas the window regulation, particularly glazing, is more influential and that for most window areas, solar impacts are generally large.     

Comparative study of porous anodic alumina: effects of aluminium deposition methods

This article reports on the comparative study of the fabrication of porous anodic alumina films by anodisation of the aluminium films on glass substrates which were deposited by direct current sputtering and electron beam evaporation methods. The relationship between surface morphology of the deposited aluminum films and porous anodic alumina films was investigated. A more uniform and ordered porous anodic alumina was obtained by fabricating from electron beam evaporation deposited aluminium film with smaller and compact grains. Two-step anodisation was used to further improve the quality of porous anodic alumina compared to one-step anodisation. The optical transmittance spectra within wavelength of 370–800 nm were obtained and the optical properties were studied.     

Investigation of the impact of global warming on precipitation pattern of Saudi Arabia

This study has been carried out to forecast the impact of global warming on the precipitation pattern of Saudi Arabia by the end of year 2100. Simulation has been done using EdGCM model software (with available 8×10 resolution) developed at Columbia University on which there have been produced global precipitation maps for the seasonal and annual averages for the last 5 years (2096–2100). For each map, EdGCM grid values surrounding Saudi Arabia are used as input to one of the tools of Eagle point software called surface modelling (SM). SM is a new approach for downscaling global climate model results. SM software modelled out isohyets at 0.2 mm/day interval. The results indicate that the present pattern of precipitation (more in winter and less in summer) is going to change by almost equal occurrence of precipitation in all seasons for double_CO₂ (2CO₂) experiment. The 2CO₂ experiment indicates an increase of about 16.05% over the annual average precipitation across the country.     

Urethane‐forming reaction kinetics and catalysis of model palm olein polyols: Quantified impact of primary and secondary hydroxyls

Model palm olein natural oil polyols (NOPs) with varying ratios of primary to secondary hydroxyls were synthesized, characterized, and evaluated in reaction kinetics study with isocyanate in formation of polyurethanes. Reaction rate constants and activation energies associated with primary and secondary hydroxyls of NOPs were quantified. The kinetic study in toluene shows that the NOP containing primary hydroxyls have three times higher reaction rate constants in noncatalyzed reaction with 4,4′‐diphenylmethane diisocyanate (4,4′‐MDI) compared to the model NOP containing only secondary hydroxyls, which is associated with higher activation energy of secondary hydroxyls. However, the difference in reaction rate constants of primary and secondary hydroxyls in NOPs diminished in the reactions catalyzed with dibutyltin dilaurate. Bulk polymerization reaction confirms the kinetics results in toluene, showing that the model NOP containing primary hydroxyls reached gel time at a faster rate. Evaluation of elastomers from bulk polymerization shows low degree of phase separation of hard and soft segments for elastomers based on the model NOPs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42955.     

A Study on the Impact of the Adhesion of Penicillium expansum on the Physicochemical Surface Properties of Cedar Wood

The sessile drop technique was used to investigate the evolution of the physicochemical properties of cedar wood as a function of contact time with the Penicillium expansum spores. The most important finding showed that the impact of different contact periods (2, 4, 6, 8, 10, and 24 hr) on the wood surface were very indicative. In fact, after 2 hr of contact, the results have shown a significant impact of the bioadhesion of spores to the substrate on both the hydrophobic character (θ_W = 108.5°; ΔGiwi = ?28.25 mJ/m²), the electron donor (γ^? = 13.63 mJ/m²), and the electron acceptor (γ⁺ = 4.35 mJ/m²) parameters that were significantly reduced compared to the initial wood (θ_W = 118.5°; ΔGiwi = ?6.29 mJ/m²; γ^? = 32.1 mJ/m²; and γ⁺ = 9.1 mJ/m²). In addition, this decrease of parameters continued over time to stabilize after 10 hr of contact. Indeed, after 24 hr, the acid/base properties were almost zero and the contact angle with water decreased to 30°. Moreover, it was found that the coefficient of correlation (r²) was strong between the contact angle with water, the surface energy, and the electron acceptor character with the contact time parameter with values (r² = 0.65), (r² = 0.79), and (r² = 0.68), respectively.