Recent developments in the coupling of photoassisted and aerobic biological processes for the treatment of biorecalcitrant compounds

A general strategy to develop combined photochemical and biological system for biorecalcitrant wastewater treatment is proposed. For the development of this strategy, the following points were taken into account: the biodegradability of initial solutions, the operation mode of the coupled reactor, the chemical and biological characteristics of the phototreated solutions, the evaluation of different photoassisted advanced oxidation processes, the optimal conditions of both photochemical and biological processes, and the efficiency of the coupled reactor.

The strategy to couple photochemical and biological processes is illustrated by case studies of four different biorecalcitrant pollutants. Three kinds of combined systems were developed using either photo-Fenton, Fe³⁺/UV, or TiO₂ supported on glass rings for the photocatalytic pretreatment and in all cases immobilized biomass for the biological step. The advantages of the each coupled system are discussed and beneficial effects of such two-step treatments were found. However this strategy is not a universal solution. Chemical, biological, and kinetic studies must be always carried out to ensure that the photochemical pretreatment increase the biocompatibility of the treated wastewater. Some field experiments using solar reactor indicated that a coupled photochemical–biological treatment system at pilot scale is a possible way to achieve the complete mineralization of the biorecalcitrant pollutants.     

The diffusion of water in poly(ditetrahydrofurfuryl itaconate)

The diffusion of water into solid poly(ditetrahydrofurfuryl itaconate) (PDTFI) films and in analogous polymer solutions was measured. Diffusion into solid PDTFI films on a glass support was measured in three solutions of different pH (4, 7 and 10) at 37 and 60 °C during a 90 day period. The uptake was high and was both pH and temperature dependent, ranging from 120 to 2000%. A Fickian mechanism is observed for the initial stages of uptake, whilst a non-Fickian mechanism is present when the equilibrium is approached. The pH 7 samples did not equilibrate at any temperature during the experiment. The FTIR investigations of the films indicated some deesterification took place during the uptake. The diffusion coefficients and diffusion exponents are calculated for the samples. The diffusion of water into PDTFI solution in acetone was measured by PGSE-NMR, showing the expected linear attenuation functions. The diffusion coefficient of water was calculated for polymer concentrations up to 10%.     

Diffusion of drugs from hydrogels and liposomes as drug carriers

BACKGROUND: The mass transfer of model drugs Lidocaine hydrochloride and Dihydroquercetin from hydrogels (the usual carriers for topical drugs), and hydrogels containing liposomes, as novel drug vehicles, was studied. Diffusion experiments were performed using a Franz diffusion cell. Experimental data were used to calculate drug diffusion coefficients across membranes, and their effective diffusion coefficients from hydrogels and liposome containing hydrogels. For the first time the diffusion resistance of all drug carriers was determined from corresponding diffusion coefficients. The main aim of this work was the study of drug diffusion coefficients from liposomes and their comparison with related diffusion coefficients from hydrogels to find how liposomes contribute to prolonged and controlled drug release. RESULTS: Drug diffusion coefficients were: 1.38 · 10^?8m² s^?1 for Lidocaine hydrochloride and 5.96 · 10^?9m² s^?1 for Dihydroquercetin, while corresponding effective diffusion coefficients from hydrogels were: 7.82 · 10^?10m² s^?1 and 7.98 · 10^?10m² s^?1, respectively. Effective diffusion coefficients from liposome‐containing hydrogels were:4.82 · 10^?10m² s^?1 (Lidocaine hydrochloride) and 4.305 · 10^?10m² s^?1 (Dihydroquercetin). Diffusion resistances for the two hydrogels were almost the same. Very similar values of diffusion resistances for all liposome dispersions were obtained. CONCLUSION: Calculated diffusion coefficients and resistances demonstrate that liposomes, as drug carriers, significantly affect diffusion rates. The results obtained could be used whenever diffusion‐controlled drug release is required. Copyright © 2010 Society of Chemical Industry     

NDTE using pulse thermography: Numerical modeling of composite subsurface defects

The ability to predict subsurface defect information in composite materials through a non-invasive, efficient inspection protocol is fast becoming a vital research area. In numerically modeling the thermographic process associated with an infrared (IR) technique we can afford inspectors the ability to predict subsurface defect information associated with a specific material configuration. The research involved in this study looks specifically at the finite element modeling (FEM) of delaminations in a composite flat plate setup. To date the modeling of delaminations has been restricted to only two dimensional (2D) numerical representations and associated primarily with rear faced detection. The results of this research, however, clearly show that the rear faced detection technique has limitations in defect depth prediction and the 2D approximation associated with this technique ignores a paramount effect in the form of lateral thermal diffusion. It is also made clear that the representation of experimental flat plate models with flat bottomed holes, under pulse phase thermographic inspection, in simulating delaminations is misguided.     

Simplified transient model of an upflow cocurrent packed bed bioreactor

A dynamic model incorporating biomass growth and liquid hold-up evolution is developed to describe a fixed bed bioreactor operation with cocurrent upflow of water and air flows. The model permits to predict cycle time and optimal operation conditions for high substrate removal and long cycle times. Simulation results are compared with published experimental results and show good model accuracy.     

Insulin-Dependent H2O2 Production Is Higher in Muscle Fibers of Mice Fed with a High-Fat Diet

Insulin resistance is defined as a reduced ability of insulin to stimulate glucose utilization. C57BL/6 mice fed with a high-fat diet (HFD) are a model of insulin resistance. In skeletal muscle, hydrogen peroxide (H₂O₂) produced by NADPH oxidase 2 (NOX2) is involved in signaling pathways triggered by insulin. We evaluated oxidative status in skeletal muscle fibers from insulin-resistant and control mice by determining H₂O₂ generation (HyPer probe), reduced-to-oxidized glutathione ratio and NOX2 expression. After eight weeks of HFD, insulin-dependent glucose uptake was impaired in skeletal muscle fibers when compared with control muscle fibers. Insulin-resistant mice showed increased insulin-stimulated H₂O₂ release and decreased reduced-to-oxidized glutathione ratio (GSH/GSSG). In addition, p47^phox and gp91^phox (NOX2 subunits) mRNA levels were also high (~3-fold in HFD mice compared to controls), while protein levels were 6.8- and 1.6-fold higher, respectively. Using apocynin (NOX2 inhibitor) during the HFD feeding period, the oxidative intracellular environment was diminished and skeletal muscle insulin-dependent glucose uptake restored. Our results indicate that insulin-resistant mice have increased H₂O₂ release upon insulin stimulation when compared with control animals, which appears to be mediated by an increase in NOX2 expression.     

Modification of hydrophilic polymer network to design a carrier for a poorly water-soluble substance

pH sensitive, nontoxic, and biocompatible poly(methacrylic) acid (PMAA) based soft networks have been extensively used in the design of systems for targeted drug delivery. Still, their highly hydrophilic nature limits their potential to be used as a carrier of poorly water-soluble substances. With the aim to overcome this limitation, the present study details a new approach for modification of PMAA based carriers using two amphiphilic components: casein and liposomes. The FTIR analysis revealed structural features of each component as well as the synergetic effect that originated from the formation of specific interactions. Namely, hydrophobic interactions between the poorly water-soluble model drug (caffeine) and casein enabled caffeine encapsulation and controlled release, while addition of liposomes ensured better control of the release rate. The morphological properties of the carriers, swelling behavior, and release kinetics of caffeine were investigated depending on the variable synthesis parameters (neutralization degree of methacrylic acid, concentration of caffeine, presence/absence of liposomes) in two different media simulating the pH environment of human intestines and stomach. The data obtained from in vitro caffeine release were correlated and analyzed in detail using several mathematical models, indicating significant potential of investigated carriers for targeted delivery and controlled release of poorly water-soluble substances.     

An Investigation of the Bias Caused by Surface Coatings on Material Loss Evaluation by Quantitative Thermography

The effect of a surface coating on the response of a metallic substrate to pulsed thermal excitation is examined with the view to assessing its impact on the efficacy of quantitative thermographic evaluation as applied to the problem of material loss evaluation. An analytical model describing the response of a layered structure to a surface thermal excitation has been developed and its predictions are shown to be in excellent qualitative agreement with experimental observations. The results indicate that for materials with high thermal diffusivity, a surface paint layer bears important influence on the development of the surface thermal response and should be taken into account when undertaking quantitative assessments of thermographic data.     

Complex landslide in the Rječina valley (Croatia): origin and sliding mechanism

This paper discusses the development of the Grohovo landslide on the north-eastern slope of the Rječina valley, the largest active landslide along the Croatian part of the Adriatic Sea coast. This complex retrogressive landslide was reactivated in December 1996. Thirteen separate slide bodies have been identified. The slide surface is considered to be on the upper flysch bedrock. Monitoring indicated that the magnitude of displacements was very different in time and space. The maximum movements were recorded on the upper part of the slope. The limestone mega-block and separated rocky blocks on top of the slope have also moved, which is not a typical phenomenon of the flysch slopes in the area of Rijeka.      

Influence of Al(OH)3 nanoparticles on the mechanical and fire resistance properties of poly(methyl methacrylate) nanocomposites

One of the drawbacks of poly(methyl methacrylate) (PMMA) is its flammability. This limits its use in many areas, particularly in constructions. Although there are several fire retardants commercially available, certain disadvantages remain. Introduction of fire retardants into PMMA can change the mechanical properties and transparency can be significantly reduced. Our attention in this study was focused on aluminium trihydroxide (ATH) nanoparticles as the filler for PMMA. To achieve better compatibility and avoid the agglomeration of nanoparticles, 2‐hydroxyethyl methacrylate was used as a co‐monomer for nanocomposite preparation. The characteristics of sheets made with ATH nanoparticles were compared to standard PMMA sheets prepared without additives. Better thermal properties and impact hardness were observed, the speed of burning was significantly lower, while complete transparency of the material was retained. POLYM. COMPOS., 37:1659–1666, 2016. © 2014 Society of Plastics Engineers