Transient dynamic phenotypes as criteria for model discrimination: fold-change detection in Rhodobacter sphaeroides chemotaxis

The chemotaxis pathway of the bacterium Rhodobacter sphaeroides shares many similarities with that of Escherichia coli. It exhibits robust adaptation and has several homologues of the latter''s chemotaxis proteins. Recent theoretical results have correctly predicted that the E. coli output behaviour is unchanged under scaling of its ligand input signal; this property is known as fold-change detection (FCD). In the light of recent experimental results suggesting that R. sphaeroides may also show FCD, we present theoretical assumptions on the R. sphaeroides chemosensory dynamics that can be shown to yield FCD behaviour. Furthermore, it is shown that these assumptions make FCD a property of this system that is robust to structural and parametric variations in the chemotaxis pathway, in agreement with experimental results. We construct and examine models of the full chemotaxis pathway that satisfy these assumptions and reproduce experimental time-series data from earlier studies. We then propose experiments in which models satisfying our theoretical assumptions predict robust FCD behaviour where earlier models do not. In this way, we illustrate how transient dynamic phenotypes such as FCD can be used for the purposes of discriminating between models that reproduce the same experimental time-series data.     

A review of the support tools for the process of assembly method selection and assembly planning

This paper reviews the substantial body of research into software and other tools to support the closely related methodologies of assembly system selection, design for assembly, and assembly planning. Reported research has led to the adoption of a number of tools in current use in manufacturing industry. Here, the scope of this research, and its practical applications, is considered with a view to identifying the application domain of each approach and support tool. The authors are led to the conclusion that there is a need for further research into a methodology for the initial selection of the assembly method (e.g. assembly line, fixed point assembly, etc), and that such a methodology should consider not only factors of product technology, but also the industrial environment where assembly is to take place. Further, a knowledge-based decision support tool could facilitate the application of this methodology, and expand decision support further into the selection of assembly planning methods for subsequent application.     

RECENT DEVELOPMENT OF GHE SOLAR DRYING IN INDONESIA

Prototypes of greenhouse effect GHE solar dryer have been tested and their technical performances for drying of tropical products have been obtained. Quality of the dried products was comparable to the existing standard used in estate plantation. The latest drying experiment with fermented cocoa beans using mechanical stirrer, and with a stationary rectangular bin for coffee berries, showed that the developed drying system was capable of reducing the total specific energy to 6.2 MJ/kg and 5.2 MJ/kg water evaporated, respectively. Therefore, the results of the study suggest that the current design could now be used in helping the farmers and fishermen to produce better quality products.     

An Experimental Study on Slurry Erosion Resistance of Single and Multilayered Deposits of Ni-WC Produced by Laser-Based Powder Deposition Process

Single and multilayered deposits containing different mass fractions of tungsten carbide (WC) in nickel (Ni)-matrix (NT-20, NT-60, NT-80) are deposited on a AISI 4140 steel substrate using a laser-based powder deposition process. The transverse cross section of the coupons reveals that the higher the mass fraction of WC in Ni-matrix leads to a more uniform distribution through Ni-matrix. The slurry erosion resistance of the fabricated coupons is tested at three different impingement angles using an abrasive water jet cutting machine, which is quantified based on the erosion rate. The top layer of a multilayered deposit (i.e., NT-60 in a two-layer NT-60 over NT-20 deposit) exhibits better erosion resistance at all three tested impingement angles when compared to a single-layer (NT-60) deposit. A definite increase in the erosion resistance is noted with an addition of nano-size WC particles. The relationship between the different mass fractions of reinforcement (WC) in the deposited composite material (Ni-WC) and their corresponding matrix (Ni) hardness on the erosion rate is studied. The eroded surface is analyzed in the light of a three-dimensional (3-D) profilometer and a scanning electron microscope (SEM). The results show that a volume fraction of approximately 62% of WC with a Ni-matrix hardness of 540 HV resulting in the gouging out of WC from the Ni-matrix by the action of slurry. It is concluded that the slurry erosion resistance of the AISI 4140 steel can be significantly enhanced by introducing single and multilayered deposits of Ni-WC composite material fabricated by the laser-based powder deposition process.     

Effect of elementary and advanced glycation products of nisin on its preservative efficacy and digestibility

Nisin used as a natural preservative in variety of food systems was subjected to glycation at 95 °C in high molar concentration. The elementary glycation end products (EGEs) and the advanced glycated end products (AGEs) formed were tested as compared to non-glycation nisin (NN) for their antibacterial activity against some food spoilage organisms such as Staphylococcus aureus, Bacillus cereus, Micrococcus luteus, Clostridium botulinum and Lactobacillus sake. The extent of hydrolysis of EGEs and AGEs by trypsin was also compared with the (NN) as control. The results have illustrated that antibacterial activity of nisin was substantially affected by the process of glycation in case of all the five organisms selected for the study, suggesting that the glycation of nisin, whether invivo or invitro will adversely affect the preservation of foods. Moreover glycation also reduced the tryptic digestibility of EGEs by 5.2% and AGEs by 50.325% as compared to NN. The data indicated that amount of nisin, if added to carbohydrate consisting foods should be increased accordingly to claim the reported shelf life of the products and food labelling in such products needs cardinal modification. Although hydrolysis of glycated nisin by trypsin is slightly decreased, however; it will not produce any adverse effect on human digestion in view of the minute amount of nisin present in the food system.     

Evaluation of Electric Arc Furnace Slag as a Potential Phosphate-Removal Substrate

A study was conducted to evaluate the performance of locally available electric arc furnace slag (EAFS) as a substrate for removing phosphorus from wastewater. First, in a laboratory study, EAFS was found to have high phosphorus removal efficiency for three P concentrations (0.3, 3.0, and 6.0 mg/L); this resulted in nearly 100% phosphorus removal in 24 h. Next, the experiment was repeated using aeration and similar phosphorus removal was observed but in a shorter contact time of 1 h. The adsorption capacity of EAFS was determined to be 1,458 mg/kg. In a pilot-scale study, over 90% P removal took place in the first 4 h under nonaerated conditions, and nearly 100% removal in 8 h. While the P removal with aeration was relatively less initially for the shorter residence times, a 100% removal was observed for the 24-h residence time.     

Selective-combustion purification of bulk carbonaceous solids to produce graphitic nanostructures

We demonstrate the use of simple thermal oxidation processes to purify bulk carbon composites produced from thermosets, which were formulated from precursor compositions containing a melt-processible organometallic Ni catalyst in an excess of carbon source. The as-pyrolyzed carbonaceous solids comprise Ni nanoparticles and interpenetrating amorphous and graphitic carbon domains, where the fraction of crystalline carbon is determined primarily by the carbonization temperature. We exploit the adventitious amorphous carbon phase as a pore-forming agent, which is subsequently removed by selective combustion, exposing the embedded graphitic nanostructures and associated metal catalyst nanoparticles, while still retaining the macroscopic dimensions of the initial thermoset polymeric solid. The pore network formed by removal of the amorphous carbon facilitates the mass transport of gas-phase molecules, such as ammonia, to the internal surfaces of the purified carbon solid. The ability to produce nanostructured graphitic carbons in bulk solid forms using simple processing methods will facilitate their development for applications ranging from electrochemical energy storage to gas sorption/filtration.     

Choice experiment study on the willingness to pay to improve electricity services

Modern forms of energy are an important vehicle towards poverty alleviation in rural areas of developing countries. Most developing countries’ households rely heavily on wood fuel which impacts on their health and socio-economic status. To ease such a dependency, other modern forms of energy, namely electricity, need to be provided. However, the quality of the electricity service, namely reliability, is an important factor in reducing this dependency. This paper discusses a choice experiment valuation study conducted among electrified rural households located in Kisumu, Kenya, in which the willingness to pay (WTP) to avoid power outages or blackouts was estimated. A mixed logit estimation was applied to identify the various socio-economic and demographic characteristics which determine preferences in reducing power outages among a household’s users. In conclusion, several of the socio-economic and demographic characteristics outlined in this paper were identified and can assist service differentiation to accommodate the diverse households’ preferences towards the improvement of the electricity service.