Mineralization of organic N originating in treated effluent used for irrigation

Reclaimed wastewater and, particularly, secondary effluent used for irrigation, may contain considerable amounts of mineral and organic N. The knowledge regarding N-transformations of effluent-originated organic N in soil is not well established. A method based on ion-exchangers (IE) was developed to remove the mineral N and other ionic species from the effluents, enabling a better follow-up of the reactions of effluent-originated organic N. Modifications of two incubation methods were used to evaluate net mineralization rates and the contributions of ammonification and nitrification of the effluent-originated organic N. A mixture of the ion-exchangers, IRN-77 (H⁺) and IRN-78 (OH^–), was found effective in removing mineral N and other ions from effluents without significantly affecting the content of organic N. In suspension-based experiments performed with a microbially active calcareous clay soil, the nitrification started after about a 1 to 4 d lag (higher lag associated with higher BOD), and the total mineral N reached plateau values after about 9 to 14 d. The time estimated for completion of ammonification of the organic N in the well-mixed and aerated suspensions was 3 to 6 d. Soil incubations were performed after adding the IE-treated effluents to small soil columns. Ammonification of both soil and effluent-originated organic N occurred concomitantly with the nitrification, making the evaluation of rates more complicated. Tracing the time differences in total mineral N between the soils irrigated with the IE-treated effluent and the blank (no added N) enabled the estimation of first order rate constants for the net mineralization of the effluent-originated organic N in: a sandy loam (0.3 wk^–1), a loess (0.4 wk^–1), and in the calcareous clay (1.1 wk^–1). About two thirds of the organic N added to the soils in the columns during the pre-incubation stage were not retained in the soils, whereas ammonium was practically not leached out. The relatively fast movement of the effluent-originated organic N in soil and its mineralization characteristics indicate that this fraction significantly affects the short (days) and middle (weeks) range transformations of N in effluent-irrigated soils.     

Polymeric Hollow‐Fiber Bundles as Immersed Heat Exchangers

Plastic immersed heat exchangers are used in various applications where chemically neutral and noncorrosive equipment is required. Their potential competitors, namely, polymeric hollow‐fiber bundles, were investigated. Three different fiber bundles were tested as immersed coolers of a hot reservoir. Two types of polypropylene hollow fibers with various outside diameters were employed. Fibers were twisted with different curvature to achieve better distribution and improve natural convection on their outer surface. Calculation by experimental results was compared with the equation for natural convection across the horizontal cylinder, which overestimates heat transfer coefficients and can be applied for only rough estimation. Experimentally achieved pressure drops agreed well with theoretical prediction for laminar flow.     

Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

Deregulated melanogenesis is involved in melanomagenesis and melanoma progression and resistance to therapy. Vitamin D analogs have anti-melanoma activity. While the hypercalcaemic effect of the active form of Vitamin D (1,25(OH)₂D₃) limits its therapeutic use, novel Vitamin D analogs with a modified side chain demonstrate low calcaemic activity. We therefore examined the effect of secosteroidal analogs, both classic (1,25(OH)₂D₃ and 25(OH)D₃), and novel relatively non-calcemic ones (20(OH)D₃, calcipotriol, 21(OH)pD, pD and 20(OH)pL), on proliferation, colony formation in monolayer and soft-agar, and mRNA and protein expression by melanoma cells. Murine B16-F10 and hamster Bomirski Ab cell lines were shown to be effective models to study how melanogenesis affects anti-melanoma treatment. Novel Vitamin D analogs with a short side-chain and lumisterol-like 20(OH)pL efficiently inhibited rodent melanoma growth. Moderate pigmentation sensitized rodent melanoma cells towards Vitamin D analogs, and altered expression of key genes involved in Vitamin D signaling, which was opposite to the effect on heavily pigmented cells. Interestingly, melanogenesis inhibited ligand-induced Vitamin D receptor translocation and ligand-induced expression of VDR and CYP24A1 genes. These findings indicate that melanogenesis can affect the anti-melanoma activity of Vitamin D analogs in a complex manner.     

Effect of hybrid polymer coating of Bioglass® foams on mechanical response during tensile loading

A simplified two-dimensional finite elements model was created for a polyvinyl alcohol (PVA) coated Bioglass^® strut undergoing tensile stresses (loading mode I). The strengthening contributions due to the infiltration of coating into surface cracks and coating's stiffness were evaluated in terms of stress intensity factor K_I and tensile stresses σ_yy in the proximity of the crack tip. The infiltration of the coating until the crack tip resulted as the most effective criterion for the struts strengthening. Bioglass^® based scaffolds were dip coated into PVA and PVA/microfibrillated cellulose (MFC) aqueous solutions and tested in tensile load. Coated samples exhibited remarkably higher tensile strength than non-coated ones, which further raised with the increased amount of MFC. Contact angle θ and linear viscosity η measurements of PVA/MFC solutions showed that MFC caused a reduction in θ and a drastic increase in η, indicating that a balance between these two effects must be achieved.     

Synthesis of trimethylene carbonate/ϵ‐caprolactone copolymers initiated with zinc alkoxide: influence of copolymer chain microstructure on thermal and mechanical properties

Ethylzinc(II ) ethoxide is a highly active and efficient initiator for the bulk polymerization of 1,3‐trimethylene carbonate and its copolymerization with ? ‐caprolactone. This initiator allows one to obtain (co)polymers with high molar masses in quite a short time. Significant difference in co‐monomer reactivity and relatively low participation of intermolecular transesterification processes lead to the obtained copolymers being characterized by a gradient chain microstructure. In ¹³C NMR spectra, in all regions, we observed the presence of triads which were distinctly represented by four peaks for the carbonyl signal. Mechanical tests showed that copolymers containing 70% and more of ? ‐caprolactone presented a relatively high Young's modulus and a very high maximum elongation factor; therefore these materials are promising in many biomedical applications. Due to the high reaction rate, we also made an attempt at copolymerization using reactive extrusion which gave promising results. © 2017 Society of Chemical Industry     

Antibacterial LDPE Nanocomposites Based on Zinc Oxide Nanoparticles/Vermiculite Nanofiller

Polyethylene (PE) nanocomposites with the zinc oxide-nanoparticles/vermiculite nanofiller were prepared in two-steps. In first step, the ZnO-np/V nanofiller were prepared by the mechanochemical method followed by a heat treatment at 650?°C for 90 min. In second step, this nanofiller was used in concentration 3, 6, 10 and 15 wt% for PE nanocomposites preparation via melt compounding technique, the nanocomposites plates were pressed. The particles morphology of the ZnO-np/V nanofiller, arrangement of the ZnO-np/V nanofiller and surface of the PE plates were studied using scanning electron microscopy, optical light microscopy and atomic force microscopy. The surface roughness of the PE plates was evaluated from AFM measurements. Structural changes of the ZnO-np/V nanofiller in PE nanocomposites were monitored using X-ray diffraction analysis and Fourier transform infrared analysis. The gradual and long-term antibacterial effect of PE nanocomposites was tested on the Gram positive bacteria E. faecalis by counting the colony forming units number.     

Graphitic Carbon in Snow

We collected several samples of fresh snow from the areas of southern New Mexico and western Texas. Samples were analyzed to determine graphitic carbon content of snow in rural and urban areas and to compare these present values with those obtained from deep ice core samples several thousand years old. To model the optical properties of snow grains containing carbon we used several different versions of effective medium approximations. Calculations are compared with microwave analog measurements to determine which of these approximations can reasonably well predict the properties of mixtures such as snow and carbon. Suggestions regarding which of the effective medium approximations that should not be used are presented.     

Dyeing of leather with microencapsulated acid dye

CI Acid Black 210 was microencapsulated into liposomic systems, and the effects of the microencapsulation on dyebath exhaustion, depth of shade, colour fastness properties and through‐dyeing of chrome‐tanned leather were studied. In comparison with the original dyestuff form, the microencapsulated dye showed a deeper shade and a greater depth of through‐dyeing. Exhaustion and colour fastness values were the same.