Surface treatment for preventing decay and termite attack in wood using didecyl dimethyl ammonium tetrafluoroborate (DBF) incorporated with acryl-silicon type resin

Surface treatment of wood was carried out using acryl-silicon type resin including didecyl dimethyl ammonium tetrafluoroborate (DBF), boron-containing quaternary ammonia compound. Surface-treated wood specimens were exposed laboratory decay resistance tests after completing a 10-cyle severe weathering process. In laboratory decay resistance tests, one brown-rot decay fungus, Fomitopsis palustris and one white-rot decay fungus, Trametes versicolor were used. The specimens were also subjected to laboratory termite resistance tests using subterranean termites, Coptotermes formosanus. Wood specimens treated with 2% DBF and resin containing preservative solution showed improved decay and termite resistance suggesting that the preservative solution at 2% DBF concentration provides lasting protection against wood degradation owing to the amount of DBF remaining in the wood after severe weathering process. However field tests are needed to determine the performance of surface-treated wood with DBF and the acryl-silicon type resin in more realistic conditions.     

Bioremediation of CCA-C treated wood by Aspergillus niger fermentation

This study evaluated the potential of the fungus Aspergillus niger to remove copper, chromium, and arsenic from waste wood treated with chromated copper arsenate (CCA) wood preservative. The removal of heavy metals by A. niger was carried out in two stages. In the first stage, A. niger was cultivated in carbohydrates media in order to produce large quantities of oxalic acid. Bioremediation of CCA-treated wood was performed in the second stage through both leaching of heavy metals with oxalic acid occurred during the first stage and possible biosorption of metals onto the binding sites in the cellular structure of A. niger. Oxalic acid production by A. niger was 13.4 kg/m³ at pH 6 and in an enriched nitrogen and phosphorus medium. CCA-treated chips exposed to A. niger for 10 days showed a decrease in arsenic of 97%. In addition, A. niger fermentation removed 49% copper and 55% chromium from CCA-treated chips. This study showed that fungal fermentation and passive metal removal by A. niger had a potential in arsenic release from CCA-treated waste wood.

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Aufwertung von CCA-behandeltem Holz durch Fermentation mit Aspergillus niger

Zusammenfassung Diese Studie untersuchte die Möglichkeit des Pilzes Aspergillus niger Kupfer, Chrom und Arsen von Abfallholz, das mit CCA-Holzschutzmittel behandelt worden war, zu entfernen. Die Entfernung von Schwermetallen durch A. niger wurde in zwei Stufen durchgeführt. Während der ersten Stufe wurde A. niger in Kohlenhydratmedien kultiviert, um große Mengen von Oxalsäure zu produzieren. Die Aufwertung von CCA-behandeltem Holz wurde während der zweiten Stufe durchgeführt. Sowohl das Auslaugen der Schwermetalle mit Oxalsäure als auch die mögliche Biosorption von Metallen an Rezeptoren in der Zellstruktur von A. niger fand während der ersten Stufe statt. Die Oxalsäure-Produktion durch A. niger betrug 13,4 kg/m³ bei einem pH-Wert 6 in einem mit Stickstoff und Phosphor angereichertem Medium. Die mit CCA behandelten Späne zeigten nach 10-tägiger Behandlung mit A. niger einen Arsenabfall von 97%. Zusätzlich entfernte die A. niger-Fermentation 49% Kupfer und 55% Chrom von CCA-behandelten Spänen. Diese Studie zeigte, dass Pilzfermentation und passive Metallentfernung durch A. niger eine Möglichkeit bot, Arsen von CCA-behandeltem Holz freizusetzen.

     

Boron removal from saline water: A comprehensive review

Boron is an essential micronutrient for plants and animals as well as a useful component for numerous industries. It is necessary to produce low boron containing water from RO desalination plants for both human consumption and for agriculture. For plants, a small amount of boron is necessary for their growth and development, but boron becomes toxic if the amount is slightly greater than required. Desalinated seawater from RO plants often contains high boron content and, when used for irrigation, has been proven to be damaging to crops including blackberry, lemon, and grapefruit. Apart from the toxic effects of boron on plants, boron should be removed from RO desalination plants to comply with the current guideline value, 0.5 mg/L, for potable water issued by the World Health Organisation (WHO). Currently there is no simple method to remove boron from saline water. The use of multi-pass reverse osmosis membrane (RO) with pH modification and the use of ion exchange using boron selective resins (BSRs) have both been considered as effective methods for the removal of boron. A hybrid process, Adsorption Membrane Filtration (AMF), has received attention as an emerging technology for boron removal with a high efficiency and low operating costs. The purpose of this review is to give an overview on boron in general and to discuss its toxicity. The problems of boron in the MENA (Middle East and North Africa) region are discussed as well as technologies, current and future, for the removal of boron from seawater. The focus is placed on current RO and ion exchange methodologies using BSRs as well as the future for the AMF method. The fundamentals of each process, the effects of experimental parameters, and findings are discussed.     

Hall current and gravity effect on magnetomicropolar thermoelastic medium with microtemperatures

This research is concerned with the effect of the gravity on micropolar thermoelastic medium possessing microtemperatures, using the modified Ohm's law taking into consideration the Hall current. The expressions for the physical quantities are obtained using the normal-mode analysis method. The comparisons established numerically and represented graphically in the presence and absence of the gravity, the Hall current effect and the micropolar property.     

Volumetric Mass Transfer Coefficient in non‐Newtonian Fluids in Spout Fluid Beds

The volumetric liquid‐phase mass transfer coefficient, k_La, was determined by absorption of oxygen in air using six different carboxy‐methyl cellulose (CMC) solutions with different rheological values in three phase spout‐fluid beds operated continuously with respect to both gas and liquid. Three cylindrical columns of 7.4 cm, 11.4 cm, and 14.4 cm diameters were used. Gas velocity was varied between 0.00154–0.00563 m/s, liquid velocity between 0.0116–0.0387 m/s, surface tension between 0.00416–0.0189 N/m, static bed height between 6.0–10.8 cm, and spherical glass particles of 1.75 mm diameter were used as packing material. A single nozzle sparger of 1.0 cm diameter was used in the spouting line. The volumetric mass transfer coefficient was found to increase with gas velocity, liquid velocity, and static bed height and to decrease with the increase of the effective liquid viscosity of the CMC solution. A dimensionless correlation was developed and compared with those listed in the literature.     

Optimization of helium refrigerators and liquefiers for large superconducting systems

A general method for optimizing ideal Claude cycles with multiple expansion engines is presented for two types of engine arrangements. In one case, the inlet temperature of one engine is equal to the outlet temperature of another engine. In the second case, inlet and outlet temperatures of adjacent engines are independent of each other, the more general case which is sometimes used in practice. The optimizing technique is especially adapted to superconductive systems in which some of the helium vapour is used to cool electrical leads and mechanical support systems. The helium fraction to be returned to the refrigerator-liquefier vs the fraction to be used for other purposes is conventionally entered as a parameter which becomes part of the optimization technique.     

Preparation and characterization of ethylenediamine and cysteamine plasma polymerized films on piezoelectric quartz crystal surfaces for a biosensor

This paper describes a method for the modification of quartz crystal surfaces to be used as a transducer in biosensors that allow recognition and quantification of certain biomolecules (antibodies, enzymes, proteins, etc). Quartz crystal sensors were modified by a plasma based electron beam generator in order to detect the level of the toxin histamine within biological liquids (blood, serum) and food (wine, cheese, fish etc.). Cysteamine and ethylenediamine were used as precursors in the plasma. After each modification step, the layers on the quartz crystal were characterized by frequency measurements. Modified surfaces were also characterized by contact angle, X-ray photoelectron spectroscopy and atomic force microscopy to determine the physical and chemical characteristics of the surfaces after each modification. Finally, the performance of the sensors were tested by the response to histamine via frequency shifts. The frequency shifts of the sensors prepared by plasma polymerization of ethylenediamine and cysteamine were approximately 3230 Hz and 5630 Hz, respectively, whereas the frequency change of the unmodified crystal surface was around 575 Hz.     

Mechanical properties and biocompatibility of plasma-nitrided laser-cut 316L cardiovascular stents

The effect of surface modification of laser-cut 316L cardiovascular stents by low-T plasma nitriding was evaluated in terms of mechanical properties and biocompatibility of the stents. The plasma nitriding was performed at 400, 450 or 500 °C using various ratios of nitrogen–hydrogen gas mixtures. The flexibility and radial strength were measured in crimped and expanded state of the stents, respectively. The mechanical properties could be adjusted and improved by plasma nitriding conducted at temperatures lower than 450 °C and/or nitrogen content less than 10% in the treatment gas. An osteoblast cell culture model system was utilized to investigate the effect of plasma nitriding of the stents on the biological response towards the stents, using biological criteria such as cell viability, alkaline phosphatase and nitric oxide production. In terms of cell viability and alkaline phosphatase production, the plasma nitriding procedure did not appear to negatively affect the biocompatibility of the 316L steel stents. However, in terms of nitric oxide production that was slightly increased in the presence of the plasma-nitrided stents, an indirect improvement in the biocompatibility could possibly be expected.     

An atomic force microscope study of calcium carbonate adhesion to desalination process equipment: effect of anti-scale agent

Whilst carbon dioxide is water soluble the system is somewhat complex and results in the presence of carbonate anions which interact with cations such as Ca²⁺ and Mg²⁺ present in seawater to form insoluble carbonates, especially at high temperatures. In multistage flash (MSF) desalination plants CO₂ gas becomes less soluble in the brine as a result of the brines high temperature and high salinity which causes the pH to be in the range of 8–9. The presence of these conditions causes the release of CO₂, simultaneous to the formation of scale deposits since its solubility is a function of the solution pH.

The formation of scale deposits, such as CaCO₃ causes fouling in the MSF distillers which has previously been studied by many researchers. A great amount of work has been carried out and more is yet to come in order to fully understand the role of various components and their interaction including the effectiveness of scale control techniques. The deposits may serve as an adsorbing film raising the speed of the loss of crystals or promoting the formation of scale deposits and therefore further adhesion on the wall surfaces of the MSF distillers and other process plant equipment leading to deterioration in the performance and efficiency of the whole desalination plant.

This paper shows direct quantification of the adhesion forces between CaCO₃ crystals and different process equipment surfaces under different conditions. This was carried out using an atomic force microscope (AFM) with an attached CaCO₃ crystal as a colloid probe to bring the CaCO₃ directly into and out of contact with the surfaces and measuring the resultant adhesion. This involved using surfaces different grades of roughness and carrying out measurements in synthetic sea water solutions of differing ionic strengths as well as with real seawater samples. Furthermore, the effect on measured adhesion of adding anti-scalant to the solutions was examined.