An algebraic approach to targeting waste discharge and impure fresh usage via material recycle/reuse networks

This paper introduces an algebraic procedure that targets material-recycle networks. The problem involves the allocation of process streams and fresh sources to process units (sinks) with the objective of minimizing fresh usage and waste discharge. First, observations from the graphical targeting approach are transformed into algebraic insights. Then, a geometrical transformation is developed to account for the possibility of using impure fresh resources. These insights and geometrical transformations are arranged through a cascade analysis, which identifies and adjusts any recycle infeasibilities so as to maximize the recycle opportunities. A systematic non-iterative algebraic approach is developed to identify rigorous targets for minimum usage of impure fresh resources, maximum recycle of process resources and minimum discharge of waste. These targets are identified a priori and without commitment to the detailed design of the recycle/reuse network. The approach is valid for both pure and impure fresh resources. The devised procedure also identifies the location of the material-recycle pinch point and addresses its significance in managing process sources, fresh usage, and waste discharge. Two case studies are solved to illustrate the ease, rigor, and applicability of the developed targeting technique and its relationship to graphical targeting techniques.     

Effect of salts and sugars on the clarity of gellan gels

The effect of glucose, fructose and sucrose (0–15 wt%) on the clarity of low acyl gellan gels (0.5 wt%) in the presence of potassium chloride (40–100 mm ), calcium chloride (10–80 mm ) and their mixtures at a total molar concentration of 80 mm , was investigated by light absorbance experiments (490 nm). The effect on gel clarity (at 100 mm KCl) of all sugar combinations, at a final concentration of 15 wt%, was also investigated. All gels with potassium were less turbid than the ones with calcium. In the case of salt mixtures, increasing concentration of calcium in the mixtures resulted in decreased clarity. In addition, turbidity increased with increasing salt concentration. Moreover, and at the higher salt concentrations, the presence of sugars resulted in clearer gels. When mixtures of sugars were added, all combinations resulted in increased clarity compared to the individual sugars.     

Rheological and sensory attributes of cream caramel desserts containing fructooligosaccharides as substitute sweeteners

The objectives of this research were to substitute (10–50%) sucrose with fructooligosaccharides (FOS) in cream caramel dessert and to study the rheological and sensory characteristics of the gels produced. Small deformation experiments showed that the substitution of sucrose with FOS led to a decrease in the solid character of the gels. Moreover, samples in which sucrose was substituted with 20% and 30% FOS exhibited lower gel strength, and sample containing 30% FOS showed more than three times lower gel strength than that with 100% sucrose. However, all samples, albeit fluids, already had a substantial gel‐like character at high temperature. According to large deformation experiments, the strength and rigidity of all samples increased with storage time. The values for both parameters were greater for the samples containing 100% and 90% sucrose. Triangle tests were performed for sensory evaluation. Panellists did not find significant differences in terms of sweetness when sucrose was substituted up to 30%. Storage was significant only for the sample with 100% sucrose, as the sensory characteristics of the sample with 10% FOS were not affected.     

Retention of selected aroma compounds by gelatine matrices

The retention of various aroma compounds (linalool, limonene, ethyl butyrate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, hexyl acetate) by gelatine gels (2.5, 5, 10 and 20 wt%) was investigated by Static Headspace Gas Chromatography. Prior to analysis the samples were left to equilibrate at 37 °C for 24 h. The selected volatiles differed in their hydrophobicity and structure. One of the major conclusions was that increased hydrophobicity, in volatiles within the same homologous series, resulted in increased release. Branched volatiles gave greater partition coefficient values than their linear counterparts. When volatiles without the same functional group were compared, no correlation between hydrophobicity and retention was observed. The different mechanical properties of the matrix, as a result of different protein concentration, also affected the aroma retention. The effect of equilibration temperature on partition coefficients was also studied. Increased temperature resulted in higher partition coefficient values, probably due to the increased volatility of the aroma compound. Both positive and negative percentage of retention values were calculated suggesting varying protein-volatile interactions.     

Managing uncertainties in a safety-constrained process system for solvent selection and usage: an optimization approach with technical, economic, and risk factors

This paper addresses the problem of managing uncertainties in a safety-constrained process system for economic performance enhancement. Within such a context, a typical solvent selection problem involves a number of different solvents with nominal property values that are utilized in various process units and requires the minimization of the total operating cost while satisfying certain technical performance criteria and process safety constraints. Practically, in any process system, property values of streams are not exact; they are usually functions of operating variables and market conditions that change over time inevitably introducing irreducible uncertainties in system performance. A key aim of the present study is to systematically explore the effect of volatility in solvent prices on the economic performance of the process. Appropriate sensitivity analysis and Monte Carlo simulation work have been carried out to assist the decision maker in taking into account the continuously changing market conditions, while identifying operationally safe feasibility regions for solvents with different risk characteristics in the underlying optimization problem. The aforementioned uncertain inputs are shown to cause shifts of the associated Pareto front of optimal solutions toward feasibility regions that can be characterized in a more realistic manner. Finally, an illustrative case study that uses the permissible exposure limit as a risk factor is considered to evaluate the proposed method.     

Mechanistic aspects of the low temperature steam reforming of ethanol over supported Pt catalysts

The influence of the support of Pt catalysts for the reaction of steam reforming of ethanol at low temperatures has been investigated on Al₂O₃, ZrO₂ and CeO₂. It was found that the conversion of ethanol is significantly higher when Pt is dispersed on Al₂O₃ or ZrO₂, compared to CeO₂. Selectivity toward H₂ is higher over ZrO₂-supported catalyst, which is also able to decrease CO production via the water-gas shift reaction. Depending on catalyst employed, interaction of the reaction mixture with the catalyst surface results in the development of a variety of bands attributed to ethoxy, acetate and formate/carbonate species associated with the support, as well as by bands attributed to carbonyl species adsorbed on platinum sites. The oxidation state of Pt seems to affect catalytic activity, which was found to decrease with increasing the population of adsorbed CO species on partially oxidized (Pt^δ+) sites. Evidence is provided that the main reaction pathway ethanol dehydrogenation, through the formation of surface ethoxy species and subsequently acetaldehyde, which is decomposed toward methane, hydrogen and carbon oxides. The population of adsorbed surface species, as well as product distribution in the gas phase varies significantly depending on catalyst reactivity towards the WGS reaction.     

High pressure treatment of brine enhanced pork affects endopeptidase activity,protein solubility,and peptide formation

In order to study the effect of high-pressure (HP) treatment and two different methods of brine addition (important for lysosomal membrane destabilisation) on lysosomal enzymes activity and protein degradation, pork semitendinosus muscle was brine enhanced by injection or tumbling, and HP treated at 600 MPa following storage at 2 °C for up to 8 weeks. In this report a novel protocol for SDS gelatin zymography was established, and an increase of cathepsin B and L activity after HP treatment was shown followed by a decrease during storage. No calpain activity was detected following HP treatment. HP treatment was shown to induce a decrease in protein solubility in both myofibrillar and sarcoplasmic fractions. LC–MS analysis of these fractions showed changes in the peptide pattern during storage. Western blot analysis showed that troponin-T was indeed degraded during storage after HP treatment. The results therefore suggest that HP treatment induced an increase in cathepsin activity, which subsequently affected the myofibrillar protein degradation pattern in pork meat.     

Feature-based 3D morphing based on geometrically constrained spherical parameterization

Current trends in free form editing motivate the development of a novel editing paradigm for CAD models beyond traditional CAD editing of mechanical parts. To this end, we need robust and efficient 3D mesh deformation techniques such as 3D structural morphing.In this paper, we present a feature-based approach to 3D morphing of arbitrary genus-0 polyhedral objects that is appropriate for CAD editing. The technique is based on a sphere parameterization process built on an optimization technique that uses a target function to maintain the correspondence between the initial polygons and the mapped ones, while preserving topology and connectivity through a system of geometric constraints. Finally, we introduce a fully automated feature-based technique that matches surface areas (feature regions) with similar topological characteristics between the two morphed objects and performs morphing according to this feature correspondence list. Alignment is obtained without user intervention based on pattern matching between the feature graphs of the two morphed objects.     

A parametric feature-based CAD system for reproducing traditional pierced jewellery

In this paper, we introduce ByzantineCAD, a parametric CAD system for the design of pierced medieval jewellery, which is jewellery created by piercing, a traditional Byzantine technique. ByzantineCAD is an automated parametric system where the design of a piece of jewellery is expressed by a collection of parameters and constraints and the user's participation in the design process is through the definition of the parameter values. We present an approach to designing traditional pierced jewellery using a voxel-oriented feature-based Computer Aided Design paradigm: a large complex pierced design is created by appropriately placing elementary structural elements. We also present a scaling algorithm for enlarging pierced designs without altering the size of the elementary structural elements used to construct them.