Aerospace medicine and biology: A continuing bibliography with indexes (supplement 364)

This bibliography lists 188 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during June 1992. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

Development of a model of the aerobic membrane bioreactor treating Illovo wastewater.

M. Sc. University of KwaZulu-Natal, Durban 2014.The Membrane Bioreactor (MBR) at Sezela, KwaZulu-Natal treats a process effluent emanating from a sugar industry by-products plant. Depending primarily on the effluent feed rate to the MBR as well as other less significant factors, the MBR tends to operate at a temperature that fluctuates between 40 and 50 °C. As a result of the temperature fluctuations the MBR may operate at either mesophilic or thermophilic temperatures. In an attempt to avoid the operational instability that accompanies the transition between temperature regimes, it would be conceivable to maintain mesophilic operation through either the removal of heat during feed increases or by continuously maintaining a low feed rate; alternatively to maintain thermophilic operation by providing auxiliary heat to the MBR when low feed rates are experienced, or by maintaining a high feed rate, possibly in conjunction with a buffer tank. A solution to the problem was sought through the formulation of a coupled dynamic mass and energy balance model, with an attached speciation routine. Development of a simulation model allowed the prediction of key operating parameters, namely the temperature, pH, substrate concentration, and volatile suspended solids (VSS) concentration. The sources of data used for modelling were laboratory experiments, historical MBR data, and literature data. Kinetic and stoichiometric coefficients of the model were determined from batch respirometric tests on the MBR furfural plant effluent feed and the activated sludge. The final model yielded a dynamic temperature (Root Mean Square Deviation (RMSD) of 1.61 and 1.34 °C) and pH (RMSD of 0.36 and 0.47) prediction over a continuous 69 day interval, where only the furfural plant effluent feed and sludge wasting rates were required as model inputs. The prediction of the substrate concentration and VSS concentration were found to be unreliable. The results of the comparison of mesophilic to thermophilic operation, through the final calibrated model, indicated that thermophilic operation was advantageous, however a rigorous economic analysis is required to substantiate this outcome. Thermophilic operation at 50 °C can handle feed rates 2.2 times higher than mesophilic operation at 40 °C, but may be more susceptible to process upsets

Maillard reactions in Spray dryers

Spray drying has been widely used in many areas, including the production of spray-dried dairy products. The combination of high protein and reducing sugars makes dairy products subject to Maillard reactions during spray drying. Therefore, it is important to investigate the kinetics of Maillard reactions in spray dryers. This thesis has started with investigating the kinetics of Maillard reactions in spray dryers with different feed compositions and inlet gas temperatures. The extent of the Maillard reactions was evaluated based on fluorometric and colourimetric methods. Proteins in the feed were found to play an important role in the reaction kinetics. Results from the laboratory-scale spray dryer suggested the particle residence time distribution (RTD) also plays a pivotal role, which determines the reaction time. A measurement system has been developed to measure the RTD of different spray dryers. Experimental results showed that the later designs of the dryers have advantages over earlier designs, mainly in terms of particle-to-gas residence ratios. Fluctuations observed in signals also demonstrated the potential connection between drying chamber geometry and the wall deposition and re-entrainment processes. Apart from experimental works, this thesis has also developed mathematical models based on different modelling approaches for predicting the Maillard reactions kinetics in spray dryers. In general, prediction results are comparable to the experimental data measured earlier in this thesis, which is a significant improvement over similar models developed in other studies. The performance of the distributed-parameter model is better compared with the lumped-parameter model, though the effects of component segregation were only approximated. In summary, this thesis has systematically investigated Maillard reactions in spray dryers from an engineering point of view

Integrated valorization of Anona Cherimola Mill. seeds

Agricultural and agro-industrial residues are often considered both an environmental and an economical problem. Therefore, a paradigm shift is needed, assuming residues as biorefinery feedstocks. In this work cherimoya (Annona cherimola Mill.) seeds, which are lipid-rich (ca. 30%) and have a significant lignocellulosic fraction, were used as an example of a residue without any current valorization. Firstly, the lipid fraction was obtained by solvent extraction. Extraction yield varied from 13% to 28%, according to the extraction method and time, and solvent purity. This oil was converted into biodiesel (by base-catalyzed transesterification), yielding 76 g FAME/100 g oil. The obtained biodiesel is likely to be incorporated in the commercial chain, according to the EN14214 standard. The remaining lignocellulosic fraction was subjected to two alternative fractionation processes for the selective recovery of hemicellulose, aiming different products. Empirical mathematical models were developed for both processes, aiming future scale-up. Autohydrolysis rendered essentially oligosaccharides (10 gL-1) with properties indicating potential food/feed/pharmacological applications. The remaining solid was enzymatically saccharified, reaching a saccharification yield of 83%. The hydrolyzate obtained by dilute acid hydrolysis contained mostly monosaccharides, mainly xylose (26 gL-1), glucose (10 gL-1) and arabinose (3 gL-1), and had low content of microbial growth inhibitors. This hydrolyzate has proven to be appropriate to be used as culture media for exopolisaccharide production, using bacteria or microbial consortia. The maximum conversion of monosaccharides into xanthan gum was 0.87 g/g and kefiran maximum productivity was 0.07 g.(Lh)-1. This work shows the technical feasibility of using cherimoya seeds, and materials as such, as potential feedstocks, opening new perspectives for upgrading them in the biorefinery framework

Modelling of batch dextransucrase production

This study concerns an industrial enzyme-producing fermentation process. The bacterium Leuconostoc mesenteroides grows in a sucrose-containing medium to produce dextransucrase, an extracellular enzyme used to convert sucrose to dextran. This microbially produced biopolymer has unique properties of medicinal use. [Continues.

Scientific, Health and Social Aspects of the Food Industry

This book presents the wisdom, knowledge and expertise of the food industry that ensures the supply of food to maintain the health, comfort, and wellbeing of humankind. The global food industry has the largest market: the world population of seven billion people. The book pioneers life-saving innovations and assists in the fight against world hunger and food shortages that threaten human essentials such as water and energy supply. Floods, droughts, fires, storms, climate change, global warming and greenhouse gas emissions can be devastating, altering the environment and, ultimately, the production of foods. Experts from industry and academia, as well as food producers, designers of food processing equipment, and corrosion practitioners have written special chapters for this rich compendium based on their encyclopedic knowledge and practical experience. This is a multi-authored book. The writers, who come from diverse areas of food science and technology, enrich this volume by presenting different approaches and orientations

The application of isothermal microcalorimetry for studying mixed probiotic cultures

The main aim of this research was to explore the potential of the isothermal microcalorimeter to detect bacteria in mixed cultures; applied to investigate the antagonistic effect of commercial probiotics against pathogens and each other; and also the prebiotic potential of a substrate. Gastric tolerance of commercial probiotic products was also investigated with an improvement on current methods. An initial mixed culture study with Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli in the microcalorimeter showed that the microcalorimeter could detect their growth in mixed cultures; S. aureus was always outcompeted in growth. Antagonistic activity of probiotic strains, Lactobacillus acidophilus, Bifidobacterium lactis, Bifidobacterium bifidum or commercial probiotic products against P. aeruginosa, E. coli, S. aureus and the clinically important gut pathogen, Clostridium difficile was demonstrated in the microcalorimeter and was shown to be pH-dependent using neutralized and unmodified cell free culture supernatant (CFS) produced by the probiotic strains. But concentrated CFS of the probiotics also inhibited the pathogenic species in a non pH-dependent manner, likely due to specific antimicrobial substances or bacteriocins. The result also demonstrated that probiotic strains could compete with each other in growth when put together. The prebiotic potential of inulin was demonstrated with the microcalorimeter using faecal slurry and pure probiotic strains. Gastric tolerance assay of commercial probiotic products in porcine gastric fluid, SGF (acidified NaCl solution) and FaSSGF (acidified NaCl solution with biorelevant amounts of bile salt, pepsin and lecithin) mimicking the fed and fasted states showed significant differences between the products and fluids. In conclusion, the research showed that the microcalorimeter is a useful in vitro tool for detecting bacterial growth in mixed cultures and studying functional characteristics of probiotics and prebiotics; overcoming some of the limitations of the conventional methods

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag