Composite Fouling on Heat Exchange Surface in Australian Sugar Mill Evaporator

Composite scale of amorphous silica and calcium oxalate is very intractable; it imposes a significant fraction of scale management cost in sugar mill evaporators. This work evaluates silica and calcium oxalate composite fouling using dynamic fouling-loop experiments under different operating conditions with and without sugar. A novel closed-loop setup simulating in a single run the effect of feed concentration in successive stages of evaporation cycle was used. Experiments under constant composition and varying thermal hydraulic effect were conducted. Results indicated synergistic effects for initial silica and calcium oxalate supersaturation values of 2.6 and 1.7. Sugar effects became significant for concentrations in the third effect and above. The fouling mechanism was particulate deposition of silica and calcium oxalate colloidal species strengthened by consolidation; fouling rate increased with decreasing interfacial energy barrier between the surface and foulant, assessed by zeta-potential analysis. Deposit characteristics and deposition rates were concentration and thermal hydraulics dependent. Results confirmed the need that the 5 × 5 (types × stages of fouling) matrix of Epstein needs to be expanded to a 6 × 6 matrix to include composite fouling as a type of fouling. In this study the composite fouling was a surface-controlled process for which the activation energy was similar to typical chemical bond strengths, explaining the role of consolidation in composite fouling. The results contribute to advancement of fundamental understanding of heat exchanger fouling and to development of scale control strategies for composite fouling minimization in sugar mill evaporators.     

Community’s evaluation of organizational legitimacy: Formation and reconsideration

With the aim of delving into the legitimacy formation mechanisms used by communities to make judgements about project organizations, this research studied the local community and surrounding environment of four oil extraction projects located in three developing countries. The results of the cross-case analysis suggest that communities' negative perceptions from government and media can influence their judgement of organizational behaviour. Additionally, this research proposes that local communities' anticipation of the consequences of protesting against the organization can make them decide not to take any action. According to institutional theory, when community individuals arrive at a legitimacy verdict about an organization, their future perceptions will mainly be influenced by this decision rather than conscious consideration of the conditions. Accordingly, this research recommends that organizations aiming to recover their reputation need to adopt compensation activities with a substantial influence on the improvement of conditions. It is only in such conditions that communities will consciously evaluate organizational legitimacy. Trivial changes in organizational behaviour will only result in adding new evidences in support of the illegitimacy of organizations.     

A novel nano drug delivery system based on tigecycline-loaded calciumphosphate coated with poly-dl-lactide-co-glycolide

The purpose of the study presented in this paper has been to examine the possibility of the synthesis of a new nanoparticulate system for controlled and systemic drug delivery with double effect. In the first step, a drug is released from bioresorbable polymer; in the second stage, after resorption of the polymer, non-bioresorbable calcium phosphate remains the chief part of the particle and takes the role of a filler, filling a bone defect. The obtained tigecycline-loaded calcium-phosphate(CP)/poly(dl-lactide-co-glycolide)(PLGA) nanoparticles contain calcium phosphate coated with bioresorbable polymer. The composite was analyzed by FT-IR, XRD and AFM methods. The average particle size of the nanocomposite ranges between 65 and 95 nm. Release profiles of tigecycline were obtained by UV–VIS spectroscopy in physiological solution at 37°C. Experimental results were analyzed using Peppas and Weibull mathematical models. Based on kinetic parameters, tigecycline release was defined as non-Fickian transport. The cytotoxicity of the nanocomposite was examined on standard cell lines of MC3T3-E1, in vitro. The obtained low values of lactate dehydrogenase (LDH) activity (under 37%) indicate low cytotoxicity level. The behaviour of the composite under real-life conditions was analyzed through implantation of the nanocomposite into living organisms, in vivo. The system with the lowest tigecycline content proved to be an adequate system for local and controlled release. Having in mind the registered antibiotics concentration in other tissues, delivery systems with a higher tigecycline content show both local and systemic effects.     

Enhancement of fracture toughness in bioactive glass-based nanocomposites with nanocrystalline forsterite as advanced biomaterials for bone tissue engineering applications

In this research, the replacement effects of bioactive glass (BG) by nanocrystalline forsterite (NF) on the biomineralization, microstructural and mechanical properties of BG-based nanocomposites were investigated. The hybrid nanocomposites with different NF contents (0, 10, 20, and 30 wt%) were prepared from the nanopowders by means of conventional cold pressing method. Surprisingly, the addition of NF provided redundant mechanisms to improve the toughness of the BG matrix without deteriorating its biomineralization properties. In addition, the resulting enhancement in the fracture toughness, observed for the first time in highly bioactive BG/NF nanocomposites, indicated the potential of the prepared nanocomposites as advanced biomaterials for load-bearing bone tissue engineering applications.     

Investigating the production and properties of Ag/TiO2/PP antibacterial nanocomposite filament yarns

In this research, investigating the possibility of producing, processing and also characterization of antibacterial organic/inorganic nanocomposite polypropylene fiber has been presented. For this purpose, PP powder and inorganic nanocomposite filler were mixed using a twin screw extruder and modified granule was produced. After producing as-spun filament yarns by a pilot plant melt spinning machine at the take-up speed of 2000 m/min, samples were drawn, textured and finally weft knitted. Physical and structural properties of as-spun and drawn yarns with constant and variable draw ratios were investigated. The experimental results revealed that the crystallinity reduction of modified as-spun yarns could be compensated by drawing process. Tensile properties of modified drawn yarns with the variable draw ratio were higher than the pure PP, whereas the inverse observation was noticed in the case of constant draw ratio. The investigation of antimicrobial activity showed a high percentage of biostatic efficiency on the modified samples.     

Voltammetric determination of 4-nitrophenol using a modified carbon paste electrode based on a new synthetic crown ether/silver nanoparticles

A novel modified carbon-paste electrode (CPE) with a new synthetic ligand: 6,7,9,10,17,18,19, 20,21, 22-decahydrodibenzo[h,r][1,4,7,11,15]trioxadiazacyclonanodecine-16,23dione(DTD)/Ag nanoparticles (AgNP) was employed for 4-nitrophenol measurement in natural water. Various parameters such as pH, modifier, accumulation time and scan rate were optimized. The proposed electrode showed a good response towards 4-nitrophenol determination. Under the optimized conditions the reduction peak current, showed a good linear relationship with the nitrophenol concentration in the range comprised between 1 × 10^− 6 mol L^− 1 and 1 × 10^− 4 mol L^− 1. The developed electrode was successfully applied for the determination of 4-nitrophenol in water samples.     

Synthesis and characterization of poly(catechol) catalyzed by porphyrin and enzyme

Catalytic polymerization of catechol was performed employing the cationic porphyrin and horseradish peroxidase (HRP) as catalysts. The obtained results demonstrate that the cationic metalloporphyrin is a more-efficient catalyst than the HRP in the catechol polymerization. The oxidative polymerization was carried out in the presence of polystyrene sulfonate (PSS) as a template. According to TGA data, poly(catechol) that is synthesized by porphyrin catalyst exhibits more thermal stability than the enzymatic catalyzed product. The GPC indicate higher molecular weight of polymer synthesized by porphyrin as a catalyst. Cyclic voltammetry measurements show that the synthesized polymers have convenient electroactivity. The poly(catechol) and its methyl and methoxy derivatives that are synthesized by porphyrin catalyst show low electrical conductivity.     

In vitro deposition of lysozyme on etafilcon A and balafilcon A hydrogel contact lenses: effects on adhesion and survival of Pseudomonas aeruginosa and Staphylococcus aureus.

PURPOSE: To compare lysozyme adsorption and absorption and bacterial adhesion interactions on conventional (etafilcon A) and silicone (balafilcon A) hydrogel contact lenses. METHOD: Lysozyme concentrations and activities associated with the lenses were determined after solvent extraction (trifluoroacetic acid/acetonitrile) and directly on the lenses without extraction with micrococcal- and micro-bicinchoninic acid (BCA) assays. Cells of bacteria with radiolabeled leucine and a cell recovery procedure were used in determinations of bacterial adhesion to lenses. RESULTS: Lysozyme was adsorbed and absorbed to the conventional etafilcon A lens at about a 10-fold greater concentration than to the balafilcon A silicone hydrogel lens. Enzyme activities on the surfaces of both lenses were similar but replenished after saline extraction only with the etafilcon A lens. Lysozyme on the lens surface showed significant lysis of Micrococcus luteus but had a negligible effect on the adhesion and survival of Staphylococcus aureus. Lysozyme did not appear to affect the survival of Pseudomonas aeruginosa on lenses. CONCLUSION: In vitro experiments show that concentrations of active lysozyme on the surface of the etafilcon A lens, unlike the balafilcon A lens which showed negligible absorption, may be sustained from the lens matrix. Lysozyme deposited on hydrogel lenses had marked activity against M. luteus but relatively minor effects on the primary adhesion of P. aeruginosa and S. aureus.     

Transient heat transfer in a fixed bed of slab-shaped and spherical particles with intraparticle conduction

The mathematical equations for heat transfer between a flowing fluid and both slab-shaped and spherical particles with intraparticle conduction in a fixed bed, are numerically solved using the method of lines. The solution for spherical particles was used to confirm previous results for zero and non-zero Biot numbers. Conditions are identified under which heat transfer to beds of slabs should not be approximated by available solutions for spheres.     

Dependence of Semiconductor to Metal Transition of VO2(011)/NiO{100}/MgO{100}/TiN{100}/Si{100} Heterostructures on Thin Film Epitaxy and Nature of Strain

We have studied semiconductor to metal transition (SMT) characteristics of VO₂(011) thin films integrated epitaxially with Si(100) through NiO{001}/MgO{001}/TiN{001} buffer layers and correlated with the details of epitaxy and nature of residual stresses and strains across the VO₂/NiO interface. Thin film epitaxy at both room and elevated temperatures is studied in detail by electron microscopy and in situ high‐temperature X‐ray diffraction techniques. The epitaxial relationship across the interface between monoclinic VO₂ and NiO is determined to be (011)_VO2||{100}_NiO and [01]_VO2||[001]_NiO at room temperature. The epitaxial alignment at the temperature of growth where tetragonal VO₂ is stable is determined as: (110)_VO2||{100}_NiO and [001]_VO2||[100]_NiO. A cube‐on‐cube crystallographic alignment is established across the NiO{100}/MgO{100}/TiN{100}/Si{100} interfaces. The misfit strains across the VO₂/NiO interface at the growth temperature are calculated and the mechanism of strain relaxation is discussed. The out‐of‐plane orientation is found to be relaxed in both monoclinic and tetragonal states of VO₂. It is shown that a compressive strain of 31.65% along the [001] direction of tetragonal VO₂ is fully relaxed via matching of multiple domains. However, a small tensile misfit strain of about 5% along [10] direction cannot relax and remains in the lattice. This tensile residual strain leads to a compressive strain along [001] axis which, in turn, results in an SMT temperature slightly lower than that of freestanding strain‐free VO₂. SMT characteristics of VO₂(011) epilayers are assessed where an amplitude of near five orders of magnitude, and a hysteresis of less than 3.6 ^°C are obtained. This study introduces VO₂/NiO thin film heterostructure integrated with silicon as a promising candidate for multifunctional devices with novel characteristics where a combination of sensing, manipulation, and response functions is needed.