Economic analysis in product design——A case study of a TCM dietary supplement

An approach for the economic analysis of chemical product design is proposed. It takes into account of customers' preference on product quality and economic considerations such as pricing, profit, market share, capital investment, and operating cost. The activities needed to support business decision making – identifying product quality, estimating product cost, calculating financial metrics, and performing make–buy analysis – are discussed.The design of a Ganoderma lucidum dietary supplement, a traditional Chinese medicinal(TCM) product, is used to illustrate all the activities in this approach.     

Development of real-time state estimators for reaction–separation processes: A continuous flash fermentation as a study case

The development of reliable on-line state estimators applicable to reaction–separation processes is addressed in this work. Artificial Neural Network-based software sensors (ANN-SS) are proposed to allow on-line measurement of key variables, with an estimation algorithm that uses secondary variables as inputs. A continuous laboratory-scale flash fermentation for bioethanol production is considered as a case study. The process consists of three interconnected units: fermentor, filter (tangential microfiltration for cell recycling) and vacuum flash vessel (for the continuous separation of ethanol from the broth). The concentrations of ethanol in the fermentor and of ethanol condensed from the flash are successfully monitored on-line using ANN-SS. The proposed model contributes to improve the understanding of the complex relationships between process variables in the reaction and separation units, which is of major importance to allow the operation of the ethanol production process near its optimum performance.     

Application of microwave heating to pervaporation: A case study for separation of ethanol–water mixtures

Membrane pervaporation experiments for dewatering of water–ethanol mixtures were conducted, using a polymeric hydrophilic membrane, under microwave and conventional heating in a multimode microwave oven and a convection oven, respectively. Three feed temperatures (33.5, 45.5 and 51.5 °C) and two feed compositions (5.5 wt% and 20 wt% water in the feed) were considered. At 20 wt% water content, higher water fluxes through the membrane were obtained in the convection oven. At lower water content in the feed (5.5 wt%), the opposite effect was observed; the water fluxes were higher under microwave heating over the considered temperature range. These differences may arise from the different dielectric properties and consequently thermal behaviour of the feed mixtures under microwave heating. Microwave coupling with ethanol is stronger than with water. Moreover, unlike water, the dielectric loss factor of ethanol increases with temperature, which makes microwave dissipation preponderant in hot areas. Hence, high ethanol concentrations in the feed can easily induce thermal gradients.     

Experimental study of a vane-type pipe separator for oil–water separation

An experimental study of a new vane-type pipe separator (VTPS) was conducted for the possible application in the well-bore for oil–water separation and reinjection. Results by using particle image velocimetry (PIV) reveal a better flow field distribution for oil–water separation, which is formed in VTPS than that in hydrocyclone. The effects of split ratio, the oil content, guide vanes’ installation and number of guide vanes on oil–water separation performance have been investigated experimentally. Compared to a traditional single hydrocyclone, VTPS shows a good separation performance as the water content at the inlet of VTPS reaches 79.9%, the oil content at the water-rich outlet is about 400 ppm while the split is near 0.70. These results are helpful to provide a possibly new design for downhole oil–water separation.     

The use of condensed silica fume to control alkali-silica reaction — a field case study

In 1980 a sidewalk was built at Bécancour, Québec, with condensed silica fume concretes containing highly reactive aggregates. Eleven concrete mixes were used with cement quantities from 140 to 405 kg of cement per m³ and condensed silica fume substitutions varying from 10 to 40%. In spite of the great reactivity of the aggregates, the alkali-aggregate reaction is still under control. Microstructural studies of four particular concretes have been made after the first and third winters. No silicate gel has been observed in the two leaner mixes but some has been found in a few locations encircling coarse aggregate particles in the two richer mixes. The severe scaling problem observed in one of the concrete is characterized at the microstructure level by frequent unbonding of coarse aggregates and presence of converging cracks around the aggregates.     

Lateral migration of cylindrical particle in a constricted microchannel—A numerical study

Inertial migration of a single cylindrical particle in a constricted microchannel is addressed in this work. A computational model (two-dimensional) has been constructed with the assistance of the immersed boundary finite volume method. The feedback forcing strategy is utilized for the simulation of lateral migration. The parameters like equilibrium position, migration time, and shortest equilibrium distance are computed to analyze the inertial migration characteristics of the particle. Also, a comprehensive parametric study has been performed on the migration behaviour of particles inside the constricted channel by addressing the effects of Reynolds number, diameter, initial release position, and constriction clearance. The parametric study shows that the equilibrium position changes with variations in the initial release position and particle diameter. On the other hand, it stays unaffected by changes in Reynolds number and constriction clearance. The parameters like the shortest equilibrium distance and migration time increase with a rise in Reynolds number and particle diameter. On the other hand, it reduces with the reduction in constriction clearance. Inspired by the parametric study results, in the following stage, a prediction model is created with an artificial neural network algorithm. This is used for an effective forecast of equilibrium position, migration time, and shortest equilibrium distance. Further, the computational model is utilized to check for the existence of a critical Reynolds number for the particle movement in a constricted microchannel. It is observed that the critical Reynolds number remains unchanged with a change in particle diameter. However, it increases linearly with an increase in constriction clearance.     

Chloroacetoxylation of oleic acid—A kinetic study

The kinetics of the addition reaction of chloroacetic acid to oleic acid (chloroacetoxylation) in the presence of sulfuric acid as a catalyst were investigated. The reactions were carried out at the same concentration of both reactants at various temperatures and catalyst content. The reaction time ranged from 30 min up to 12 h, and the reaction course was observed by determining mainly iodine value, and chlorine content of the oil samples at 30-min intervals. The experimental data fitted the reversible second-first order rate equation for bimolecular-unimolecular type reactions. The reaction constants of the forward and reverse reactions were obtained at temperatures 70 and 80°C. The effect of sulfuric acid content on the reaction constant was investigated at 70 and 80°C.     

Low temperature oxidation of coals—a calorimetric study

The rates of heat liberation and oxygen consumption due to coal oxidation were measured in the temperature range 20–170 °C using coals ranging from subbituminous to anthracite. It was found that the Elovitch equation fit the results for the heat generation rate excellently when it was modified slightly to include a corrective term representing the heat generation rate at the steady state. The oxygen consumption rate at a given temperature was found to be proportional to the product of the internal surface area and oxygen content of the coals, indicating that the oxygen containing surface groups are acting as reactive sites. Using these results, the heat evolved per mole of oxygen at steady state was calculated to be 75–90 kcal/mol.     

Phase transformation and self-assembly behavior of supramolecular rod–comb block copolymers

We investigated the self-assembly behavior of a series of supramolecular rod–comb block copolymer complexes made by the hybridization of rod–coil diblock copolymers of poly (2,5-di(2-ethylhexyloxy)-1,4-phenylene vinylene)-b-poly(2-vinyl pyridine) (PPV-b-P2VP_f) with different volume fractions, f, of the P2VP coils and an anionic surfactant, dodecyl benzenesulfonic acid (DBSA), that selectively interacts with the P2VP to form the side-chain comb teeth. The resulting hybrids show hierarchically ordered structures at multiple length scales, forming so-called structure-in-structure morphology. Notably, for PPV-b-P2VP_0.56(DBSA)_x, the larger-scale structure changes from a lamellar phase, to a broken lamella, and eventually to a hexagonally packed strip phase with increasing DBSA molar ratio (x) to P2VP monomer unit. Furthermore, simultaneous SAXS and WAXS measurements showed that the order-disorder transition temperatures of larger-scale structures in the PPV-P2VP_0.56(DBSA) rod–comb systems were higher than those associated with the pristine PPV-P2VP_0.56 polymers. The large-scale structure of PPV-P2VP_0.56(DBSA) exists at temperatures around 210 °C even though the rod–rod interaction between PPV blocks disappear at ∼120 °C, signifying that the formation of the P2VP(DBSA) lamellar mesophase plays a critical role in forming the large-scale hexagonally packed strip structures.     

Comprehensive management of mineral scale deposition in carbonate oil fields – A case study

The majority of oilfields, especially those under water injection suffer from scale deposition. The common method of addressing the scale issue is to deploy the integrated scale risk management, by which the data from all available disciplines such as Chemistry, Field Engineering, Completion Engineering, etc. are integrated to make the most suitable decision. The main aim of this study is to perform integrated scale risk management in the A carbonate oil field, under water injection.     

Synthesis,Characterization and Application of a Multi-Site Phase Transfer Catalyst in Radical Polymerization of n-Butyl Methacrylate—A Kinetic Study

The multi-site phase transfer catalyzed radical polymerization of n-butyl methacrylate (n-BMA) using newly synthesized and characterized 1,1,2,2-tetramethyl-1-benzyl-2-n-propylethylene-1,2-diammonium bromide chloride (TMBPEDBC) as a multi-site phase transfer catalyst was investigated in an aqueous-organic two-phase system at 60 ± 1°C under nitrogen circumstances. The kinetics and effects of various operating variables (monomer, initiator, catalyst, temperature, acid, and ionic strength) on the rate of polymerization (Rp) were examined in detail. The order with respect to monomer, initiator and multi-site phase transfer catalyst was found to be 0.50. A suitable kinetic reaction scheme has been proposed to account for experimental observations, and its significance is discussed.     

A novel silane system as a primer for orthodontic bonding—A pilot study

AimTo determine the adhesion strength (measured as shear bond strength, SBS) of orthodontic brackets using two experimental silane-based primer systems and compare and contrast their effect.Materials and methodsSixty acid-etched premolars were randomly assigned into 4 study groups (n=15). In group 1, brackets were bonded without primer but using Transbond XT adhesive; in group 2, Transbond XT primer was applied and bracket bonded; in group 3, an experimental silane-based primer of 1.0 vol% of 3-acryloxypropyltrimethoxysilane (ACPS) was applied before bonding; in group 4, an experimental silane-based primer of 1.0 vol% of ACPS+0.5% bis-1, 2-(triethoxysilyl) ethane (BTSE) was used. The adhesion strength (measured as shear bond strength) was recorded using a universal testing machine. Failure types were classified according to the Adhesive Remnant Index (ARI). Contact angles of the primers were measured on an enamel slab.Data was analyzed by ANOVA and Tukey's multiple comparison post hoc analysis.ResultsThe mean adhesion strength results were high in group 4: 15.8±1.6 MPa followed by group 3: 12.5±1.5 MPa, group 2: 11.9±1.1 MPa and the lowest in group 1: 08.1±0.7 MPa. A significant difference in adhesion strength was observed between all the groups except for group 3 and group 4 (p<0.01).The ARI score was distributed largely to 0 and 1. One instance of enamel fractures was recorded in group 1. The contact angle measurements suggested that the lowest value with the experimental primer containing (ACPS+BTSE) was, <5° followed by Transbond XT, 41.86±4.56°.ConclusionThe experimental silane primer systems were hydrophilic in nature and demonstrated higher adhesion strength compared to traditional orthodontic primers.     

Effects of surface initial condition on aqueous corrosion of glass—A study with a model nuclear waste glass

Being a nonequilibrium material, the structure of glass varies with the sample history. Thus, the initial surface condition of a glass can vary with the preparation condition and have a large impact on its reactivity. This paper shows that the aqueous corrosion behavior of international simple glass (ISG) varies depending on the initial surface state. The ISG glass samples were prepared as-polished-only and polished-then-annealed and they were immersed in aqueous solution saturated with soluble SiO₂ at 30°C (modeling a mild condition) and at 90°C (modeling a severe condition). Molecular dynamics simulations were performed to obtain coordination numbers of network formers of ISG to assist oxygen speciation calculations. The surface structures of as-prepared and corroded ISG samples were analyzed using various imaging and spectroscopic techniques. Among these analyses, only the oxygen speciation with x-ray photoelectron spectroscopy showed discernable differences between two uncorroded surfaces with different preparation histories; all other methods could not differentiate the surface preparation history before aqueous corrosion. Such minor difference in chemical structures was found to have a profound impact on corrosion behaviors in the mild condition. In the harsh condition, the surface history dependence was not as drastic as the corrosion in the mild condition. The analysis results of the corroded surfaces suggested that the thickness and structure of the alteration layer formed on ISG in aqueous corrosion can vary with the initial surface state.     

Farmers' perceptions and management of soil organic matter – a case study from West Africa

A farm survey was carried out in 155 Ghanaian villages covering parts of the forest and savanna zones of West Africa to assess farmers' views on ‘soil organic matter’ (SOM) and its management. The results of a closed questionnaire accompanied by open discussions showed that most farmers are well aware of SOM and its importance for crop yields. In southern Ghana, farmers perceive SOM generally by its colour, while in northern Ghana, it is mostly assessed by the density and kind of vegetation. Farmers' perception of the properties of SOM was directed at its main functions as a primary provider of plant nutrients and its ability to conserve water. Other properties mentioned were the improvement of soil aeration and drainage, the loosening of soil structure as well as its impact on soil temperature. The major strategies farmers used in maintaining or augmenting SOM levels were: manure application, mulching with crop residues, slashing weeds without burning, composting, and shifting cultivation (natural fallow). Promoted technologies, such as green manuring, no tillage, or agroforestry were used only by a few of the farmers interviewed. The differences between farmers' views and strategies in the two zones as well as farmers' constraints in SOM management are discussed. It appears that the level of farmers' commitment to excellent soil management can vary with biophysical as well as socio-economic conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Immobilization of multi-enzyme in porous solid supports—a theoretical study

A theoretical study is presented dealing with the immobilization of two enzymes into a porous solid support. The developed model basically takes into account the interplay between restricted diffusions of two enzymes within intraparticle void space and their competitive adsorptions onto available functional sites on the interior surfaces. Simulations have shown that parameters such as binding rates of enzymes, initial bulk concentration ratio, pellet size and impregnating time have significant influence on the eventual distribution of two enzymes within the porous solid supports.     

Simulation of the separation of a helium–methane mixture in a flat membrane module

The problem of the membrane separation of a helium–methane mixture containing 0.1 wt % He, which imitates the composition of a helium-rich natural gas field, has been numerically analyzed. The helium and methane flux distribution along the length of a flat-sheet membrane module have been calculated. The distribution of the average mass concentration of helium in the channels is presented. The gas pumping expenditures have been estimated. The optimal working parameters of the gas mixture have been determined. Heating the mixture above 400 K does not enhance the helium–methane separation efficiency.     

Interaction of curcumin with human serum albumin—A spectroscopic study

Curcumin (diferuloyl methane) has a wide range of physiological and pharmacological actions. Curcumin interaction with human serum albumin (HSA) has been followed by fluorescence quenching and circular dichroism (CD) measurements. Based on fluorescence measurements, the equilibrium constant for the interaction is 2.0±0.2×10⁵M⁻¹. Binding of curcumin to HSA induces an extrinsic CD band in the visible region. From the induced CD band measurements, the equilibrium constant has a value of 2.1±0.3×10⁴M⁻¹. Thus, HSA has two kinds of affinity sites for curcumin, one with high affinity and the other with lower affinity. Job’s plot indicated a binding stoichiometry of 1∶1 for the high-affinity site. The equilibrium constant was invariant with temperature in the range of 15 to 45°C, suggesting the role of hydrophobic interactions in the binding of curcumin to HSA. Curcumin does not change the conformation of the HSA molecule. These measurements have implications in the understanding of the curcumin transport under physiological conditions.