Numerical investigation of thermal disassociation of ZnO for hydrogen production: Parametric study and reactor configuration

The present research is focused on the two‐step ZnO/Zn thermochemical water splitting cycle for hydrogen production. In the present paper, the numerical modeling of the first step, which involves endothermic reduction of zinc oxide (ZnO), is carried out in a cylindrical reactor using Computational Fluid Dynamics (CFD). The parametric study shows that the fractional conversion of ZnO increases with an increase in the flow rate of ZnO, while it decreases with an increase in the ZnO particle diameter and carrier gas mass flow rate. Six different reactor configurations are also assessed comprehensively. It is observed that a cylindrical reactor with a tangential inlet at the top plane and a tangential outlet at the bottom plane has higher robustness to the variation of various operating parameters with consistently high ZnO fractional conversion. Copyright © 2013 John Wiley & Sons, Ltd.     

A computational study of unsteady radiative magnetohydrodynamic Blasius and Sakiadis flow with leading‐edge accretion (ablation)

The present study investigates the influence of the magnetic field, thermal radiation, Prandtl number, and leading‐edge accretion/ablation on Blasius and Sakiadis flow. The convective boundary condition is employed to investigate the heat transfer. The nondimensional governing boundary layer equations have been solved by the homotopy analysis method for different values of the pertinent parameters. The effects of these parameters on the dimensionless velocity, temperature, skin friction, and Nusselt number are also investigated for various values of relevant parameters affecting the flow and heat transfer phenomena. The most relevant outcomes of the present study are that enhancement in magnetic field strength undermines the flow velocity establishing thinner velocity boundary layer for both Blasius and Sakiadis flows while an increase in accretion/ablation effect at leading‐edge manifests in a deceleration in velocity for Blasius case and the opposite trend is observed for Sakiadis flow. Another important outcome is that an increase in radiation and accretion/ablation at leading‐edge upsurges the fluid temperature leading to enhancement in the thermal boundary layer. For both Blasius and Sakiadis flow, the skin friction coefficient and the heat transfer rate decline with the enhancement of the leading‐edge accretion parameter. The results are compared with the existing data and are found in good agreement.     

Carob Kibble: A Bioactive‐Rich Food Ingredient

Carob (Ceratonia siliqua L.) is well known for its valuable locust bean gum obtained from the carob seeds. Separation of seeds from the pod leaves behind the carob kibble which is a good source of dietary fiber, sugars, and a range of bioactive compounds such as polyphenols and pinitol. Bioactive compounds present in carob kibble have been found to be beneficial in the control of many health problems such as diabetes, heart diseases, and colon cancer due to their antidiabetic, antioxidant, and anti‐inflammatory activities. Carob kibble has substantial potential to be used as a food ingredient. This article focuses on the composition, health benefits, and food applications of carob kibble.     

Thermodynamic screening of suitable oxygen carriers for a three reactor chemical looping reforming system

Hydrogen (H₂) production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative process which utilizes fossil fuels as feed stocks. This process occurs in three steps by employing an oxygen carrier (OC), which is generally a transition metal. As the OC plays an important role, its selection should be done after carefully considering the chemical and physical properties of the material. In this study, various candidate materials for use in a TRCLR process, with methane (CH₄) as a fuel stock, were investigated. The results show that the iron (Fe)- and molybdenum (Mo)-based OCs oxidize CH₄ completely in the FR at low temperatures. In terms of H₂ yield, tungsten (W)-based OCs produce the highest yield, ～3.9 mol-H₂/mol-CH₄. The equilibrium oxygen partial pressures and the solid circulation rates are the highest for Fe-based OCs. The oxygen carrying capacity of Fe-based OCs is relatively high while its price is low. Therefore, among the OCs investigated, Fe-based OCs were identified as the preferred OC option for a TRCLR process.     

Different feed presentations affect subsequent feed sorting and rumen pH for a short period in weaned calves

The objective of this study was to investigate the short- and long-term effects of different feed presentations on feed sorting and rumen pH in weaned calves. Thirty-six weaned female calves at the age of 12 wk (78 d) were raised in pairs (18 pens; n = 6/treatment) and randomly exposed to 1 of 3 feed presentation treatments: (1) concentrate ration (CON, only exposed to concentrate); (2) separate ration (CH, exposed to concentrate and hay as separate components); and (3) mixed ration (Mix, exposed to a mixed diet containing 75% concentrate and 25% hay). After 4 wk (from d 78 to 105) on different feed presentations, all weaned calves were introduced to a novel total mixed ration (TMR) for another 12 wk (from d 106 to 189). Fresh feed and orts were sampled daily before (wk 12 to 15) and after (wk 16, 17, and 28) transitioning to a TMR diet for analysis of feed sorting. Rumen fluid was sampled in wk 12, 13, 15, 16, 17, and 28 to determine rumen pH. The performance of weaned calves was affected by the different feed presentations during the pre-changing period, such that calves fed CON had a lower dry matter intake (DMI) and average daily gain than calves fed CH and Mix diets. When calves were introduced to the Mix diet, they immediately developed a higher degree of sorting behavior against the long particle fractions. Upon transition to TMR, we did not observe any differences in the performance of calves. However, the sorting behavior established in Mix calves persisted and was similar to calves previously fed the CON diet, whereas the extent of feed sorting in calves initially fed CH was less compared with that in the other 2 treatments in wk 16 and 17. Before changing the diet was transitioned to a TMR, calves fed CON had a lower rumen pH than calves fed CH and Mix. Although rumen pH in all treatments increased to the same level after the diet changed, we observed a tendency toward lower rumen pH in calves fed Mix compared with calves fed CH at wk 17, which might have resulted from the higher degree of feed sorting in these calves. However, by the end of the experiment (wk 28), feed sorting and rumen pH were similar across all treatments. These results indicated a short-term effect of previous feed presentations on subsequent feed sorting and rumen pH, but in the long term disappeared.     

预防组培中蓖麻子叶节玻璃化的研究

为了预防蓖麻子叶节在组织培养过程中的玻璃化现象,以建立其高效的遗传转化体系,本实验对影响子叶节生长状态的几个因素进行了初步研究。结果表明,在胚轴、子叶均为淡黄色的时期切取蓖麻子叶节,接种在1/8MS、内含10g/L琼脂粉、20g/L蔗糖、8.0mg/LZT、1.0mg/LNAA的培养基中进行培养,能有效地预防蓖麻子叶节玻璃化。     

Variation in oil content and fatty acid composition of the seed oil of Acacia species collected from the northwest zone of India

BACKGROUND: The oil content and fatty acid composition of the mature seeds of Acacia species collected from natural habitat of the northwest zone of the Indian subcontinent (Rajasthan) were analyzed in order to determine their potential for human or animal consumption. RESULTS: Oil content varied between 40 and 102 g kg^?1. The highest oil content was obtained in Acacia bivenosa DC. (102 g kg^?1) among the nine Acacia species. The fatty acid composition showed higher levels of unsaturated fatty acids, especially linoleic acid (～757.7 g kg^?1 in A. bivenosa), oleic acid (～525.0 g kg^?1 in A. nubica) and dominant saturated fatty acids were found to be 192.5 g kg^?1 palmitic acid and 275.6 g kg^?1 stearic acid in A. leucophloea and A. nubica respectively. Seed oils of Acacia species can thus be classified in the linoleic–oleic acid group. Significant variations were observed in oil content and fatty acid composition of Acacia species. CONCLUSION: The present study revealed that the seed oil of Acacia species could be a new source of high linoleic–oleic acid‐rich edible oil and its full potential should be exploited. The use of oil from Acacia seed is of potential economic benefit to the poor native population of the areas where it is cultivated. The fatty acid composition of Acacia seed oils is very similar to that reported for commercially available edible vegetable oils like soybean, mustard, sunflower, groundnut and olive. Hence the seed oil of Acacia species could be a new source of edible vegetable oil after toxicological studies. Copyright © 2012 Society of Chemical Industry     

Experimental and theoretical examination of surface energy and adhesion of nitrifying and heterotrophic bacteria using self-assembled monolayers

Biofilm-based systems, including integrated fixed-film activated sludge and moving bed bioreactors, are becoming increasingly popular for wastewater treatment, often with the goal of improving nitrification through the enrichment of ammonia and nitrite oxidizing bacteria. We have previously demonstrated the utility of self-assembled monolayers (SAMs) as tools for studying the initial attachment of bacteria to substrata systematically varying in physicochemical properties. In this work, we expanded these studies to bacteria of importance in wastewater treatment systems and we demonstrated attachment rates were better correlated with surface energy than with wettability (water contact angle). Toward the long-term goal of improving wastewater treatment performance through the strategic design of attachment substrata, the attachment rates of two autotrophic ammonia-oxidizing bacteria (Nitrosomonas europaea and Nitrosospira multiformis) and a heterotroph (Escherichia coli) were evaluated using SAMs with a range of wettabilities, surface energies, and functional properties (methyl, hydroxyl, carboxyl, trimethylamine, and amine terminated). Cell attachment rates were somewhat correlated with the water contact angles of the SAMs with polar terminal groups (hydroxyl, carboxyl, trimethylamine, and amine). Including all SAM surfaces, a better correlation was found for all bacteria between attachment rates and surface free energy, as determined using the Lewis Acid-Base approach. The ammonia-oxidizers had higher adhesion rates on the SAMs with higher surface energies than did the heterotroph. This work demonstrated the successful application of SAMs to determine the attachment surface preferences of bacteria important to wastewater treatment, and it provides guidance for a new area of research aimed at improving treatment performance through rational attachment surface design.     

Analysis of solar desiccant cooling system for an institutional building in subtropical Queensland,Australia

Institutional buildings contain different types of functional spaces which require different types of heating, ventilating and air conditioning (HVAC) systems. In addition, institutional buildings should be designed to maintain an optimal indoor comfort condition with minimal energy consumption and minimal negative environmental impact. Recently there has been a significant interest in implementing desiccant cooling technologies within institutional buildings. Solar desiccant cooling systems are reliable in performance, environmentally friendly and capable of improving indoor air quality at a lower cost. In this study, a solar desiccant cooling system for an institutional building in subtropical Queensland (Australia) is assessed using TRNSYS 16 software. This system has been designed and installed at the Rockhampton campus of Central Queensland University. The system's technical performance, economic analysis, energy savings, and avoided gas emission are quantified in reference to a conventional HVAC system under the influence of Rockhampton's typical meteorological year. The technical and economic parameters that are used to assess the system's viability are: coefficient of performance (COP), solar fraction, life cycle analysis, payback period, present worth factor and the avoided gas emission. Results showed that, the installed cooling system at Central Queensland University which consists of 10 m² of solar collectors and a 0.400 m³ of hot water storage tank, achieved a 0.7 COP and 22% of solar fraction during the cooling season. These values can be boosted to 1.2 COP and 69% respectively if 20 m² of evacuated tube collector's area and 1.5 m³ of solar hot water storage volume are installed.