Spray Coating of 2- and 3-D Solid Substrates Using a Sulfated Polysaccharide for Marine Antifouling Applications

Marine antifouling coating using functional polymers has emerged as an important tool to combat marine fouling. Owing to their natural abundance, polysaccharides represent a more sustainable option than synthetic polymers and carrageenan, a sulfated polysaccharide, is identified as a promising candidate for further research based on its excellent marine antifouling properties. However, existing research has only explored the application of carrageenan-based coatings for 2D objects, using techniques such as spin-coating. Here, a spray-coating method is proposed to apply carrageenan-based coatings to the surfaces of 2- and 3-D objects. The coated surfaces exhibit high stability under various chemical/physical stresses and high resistance to protein adsorption and marine diatom adhesion.     

Superabsorbent hydrogel based on modified polysaccharide for removal of Pb2+ and Cu2+ from water with excellent performance

This contribution describes the absorption percentage of Pb²⁺ and Cu²⁺ from water by a superabsorbent hydrogel matrix (SH) made from an anionic polysaccharide copolymerized with acrylic acid (AAc) and acrylamide (AAm). Metal‐absorption tests, upon sequential pH variation, indicated that the SH has pH‐sensitivity for the absorption of both metals from solution, attributed to the functional ionic groups (? COOH) present in the AAc and arabic gum (AG) segments. At the pH 5.0, the SH exhibited good absorption capacity: 73.10% for Pb²⁺, 81.99% for Cu²⁺ in water and 63.64% for Pb²⁺, and 76.67% for Cu²⁺ in saline water with 0.1 mol kg^?1 ionic strength. A replicated 2² full factorial design with a central point was built to evaluate the maximum absorption capacity of the metals into the SH. It was found that both the interaction and main effects of the pH and the initial concentration of metal solution on absorption percentage of the metals were statistically significant. Surface response plots indicated that the absorption capacity of both metals into the SH may be appreciably improved by using the solutions with lower initial concentration of metal and with higher pH values. Metal‐absorption results demonstrated that the SH is a convenient material for absorption of Pb²⁺ and Cu²⁺ from pure aqueous and saline aqueous environments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Antimicrobial protection of cotton and cotton/polyester fabrics by radiation and thermal treatments. I. Effect of ZnO formulation on the mechanical and dyeing properties

Cotton and cotton/polyester fabrics were treated against microbial attack by applying a formulation based essentially on ZnO under high‐energy radiation and thermal curing. To achieve the homogeneity and the reactivity of the treating formulation, a binder (Impron MTP) and a dispersing agent (Setamol WS) were used with ZnO. The antimicrobial property of the fabrics was evaluated, in terms of mechanical properties, by a soil burial test. Moreover, the effect of antimicrobial finishing on the dyeing properties in terms of color strength was investigated. It was found that the best composition that affords the best antimicrobial protection to cotton fabrics contains 2% ZnO, 2% binder, and 1% dispersing agents. For the cotton/polyester blend, the best results were achieved at the same conditions except the ZnO was 1%. It was found that the treatment under the effect of electron‐beam irradiation is better than that of gamma irradiation and thermal curing. The results showed that when the finishing process was carried out before dyeing with a reactive dye, it affects the color strength rather than performing the finishing after the dyeing process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1129–1137, 2003     

Potential of microbial growth control in water hydraulic systems by UV‐irradiation and filtration

Water hydraulic systems use water as a pressure medium and, thus, do not pose such adverse environmental impacts as oil hydraulics. Microbial deterioration of the pressure medium and biofouling of the surfaces restrict the applicability of the water‐based technology. The potential of microbial growth control by UV‐irradiation and filtration was studied in a pilot‐scale water hydraulic system. The UV‐irradiation (25 m Ws cm^?2) of the pressure medium reduced the total viable counts of bacteria by 1–2 log₁₀ cfu cm^?3, whereas the total microbial cell numbers and the numbers of surface‐attached microorganisms remained unaffected. Prefiltration (1.2 µm, absolute) of the pressure medium decreased the total microbial cell number in the water phase and retarded the attachment of bacteria. The filtration during the operation (2 µm, absolute) decreased the total numbers of microbial cells and the total viable counts in the pressure medium, and microbial attachment on the surfaces. Microbial attachment was not prevented by filtration. The microbial water quality obtained by pre‐ and on‐line filtration of the pressure medium was sufficient to ensure the long‐term operation of the water hydraulic system assuming that clean work practices are complied with in assembly and during the operation. © 2002 Society of Chemical Industry     

Modification of oxidizing activity of Thiobacillus ferroxidans by some particulate solids

Different particulate solids such as glass powder, various types of activated carbon and bentonite suspended in Thiobacillus ferrooxidans cultures produce very different effects on the oxidizing activity of the microorganism. The atmospheric oxygen uptake by Thiobacillus ferrooxidans in Warburg respirometer flasks containing 9K medium with ferrous sulfate as energy source and suspended bentonite is 2.8 times that in the absence of solids. The dissolution rate of pure pyrite in 250 cm³ shake flasks containing 9K medium and bentonite is considerably enhanced over that where the only solid phase is pyrite. Conversely, the oxidizing ability of the microorganism seems to be inhibited by all the activated carbons tested. The effect of ground glass seems to be related to its particle size distribution. Implications for the bioleaching of sulfide ores and coal pyrite are discussed in the light of current knowledge on the adsorption of Thiobacillus ferrooxidans cells on solid surfaces.     

Lipid hydrolysis and oxidation on the surface of milled rice

The changes in milled rice FFA content and composition and in conjugated diene (CD) content and bacterial, yeast, and mold counts were determined at 24, 37, and 50°C and 70% RH over 50 d. There was a rapid rate of FFA formation during the first few days of storage, which was optimal at 37°C, but that slowed after 2, 4, and 5 d at 37, 24, and 50°C, respectively. There was a second increase in FFA after about day 12 that increased with increasing temperature, indicating nonlipase hydrolysis. Linoleic and oleic acids were the main components of the total FFA produced on the surface of milled rice. The pattern of CD development followed that of FFA increase. Bacterial growth correlated with increased FFA levels after 12 d of storage, suggesting that bacterial lipase rather than bran lipase may be responsible for rice lipid hydrolysis     

微生物聚酯的合成和应用研究进展

微生物聚酯是由发酵技术生产、具有生物降解性的热塑性高分子材料。本文介绍了３－羟基丁酯均聚物（ＰＨＢ）和共聚物的基本结构、生物降解性能、生物合成及其应用研究的进展。     

Enzymatic degradation of thermoresponsive poly(N‐isopropylacrylamide) grafted to carboxymethylcellulose copolymers

The enzymatic degradation of poly(N‐isopropyl acrylamide) (PNIPAM) grafted to carboxymethylcellulose (CMC) copolymers with a cellulasic preparation (Trichoderma viride) was studied. The enzymatic activity of the cellulasic preparation against CMC and the grafted copolymers was determined by the Petterson–Porath method, while their reduced viscosity variation in the presence of the same preparation was also followed. It has been shown that the enzymatic degradation behavior depends on the copolymer composition and the reaction temperature. Reducing sugars analysis showed that the experimental values for the grafted copolymers were higher than the calculated ones. At 50°C, the enzymatic reaction is completed in about 20 min for the copolymers, whereas for CMC it takes more than 40 min. It can be concluded that their enzymatic degradation is facilitated by the presence of the PNIPAM grafts. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1383–1386, 2003     

Biodesulfurization of dibenzothiophene sulfone by Arthrobacter sp. and studies with oxidized Illinois No. 6 coal

A bacterium identified as Arthrobacter sp. was grown on dibenzothiophene (DBT) sulfone as a sole source of sulfur, producing sulfite and sulfate. Sulfur in DBT sulfone (1.0 mM) was nearly quantitatively converted to sulfate by the organism. The organism could also use DBT sulfone as a sole source of carbon and energy. There was evidence for transient accumulation of benzoic acid in the culture medium after growth of the cells slowed. The DBT sulfoxide analogue 9-fluorenone was converted by resting cells to a product identified as 1,10-dihydroxy-1,10-dihydrofluoren-9-one, suggesting that DBT sulfone may be metabolized via an angular hydroxylation resulting in carbon- sulfur bond cleavage. This strain of Arthrobacter showed no ability to desulfurize oxidized Illinois No. 6 coal.     

Improved methods for evaluating the molar mass distributions of cellulose in kraft pulp

Multi‐angle laser light scattering (MALLS) was used to characterize birch kraft pulps with respect to their absolute molecular mass distributions (MMDs). The pulps were dissolved in lithium chloride/N,N‐dimethylacetamide and separated by size exclusion chromatography (SEC). The weight‐average and number‐average molecular masses of the cellulose fractions of the pulps obtained from the absolute MALLS measurements were compared with the molar masses obtained by direct‐standard‐calibration relative pullulan standards. Discrepancies between the two detection methods were found, and two ways of correlating the relative pullulan molar masses to the absolute molar masses were examined. In the first method, the correlation was made over a large range of molecular masses. The second method correlated the molecular masses of the standards to the molecular masses of samples by the calculation of fictitious, cellulose‐equivalent molar masses of the standards. With the preferred second method, a more correct MMD of kraft pulp samples could, therefore, be obtained from an SEC system calibrated with narrow standards. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1170–1179, 2003