Aerobic degradation of 2,4-dinitrotoluene by individual bacterial strains and defined mixed population in submerged cultures

The degradation efficiencies of isomeric mononitrotoluenes (2- and 4-NTs) and dinitrotoluenes (2,4-DNT and 2,6-DNT) by either individual bacterial strains (Bacillus cereus NDT4, Pseudomonas putida NDT1, Pseudomonas fluorescens NDT2, and Achromobacter sp. NDT3) or their mixture were compared in submerged batch cultivations. The mixed culture degraded 2,4-DNT nearly 50 times faster than any of the individual strains. The mixed culture also demonstrated significantly shorter lag periods in 2,4-DNT degradation, a lack of nitrite or organic intermediates accumulation in the liquid medium and the ability to degrade a broader spectrum of nitrotoluenes over a wider concentration range. The presence of both readily degradable 2-NT (or 4-NT) and poorly degradable 2,6-DNT in the medium negatively affected 2,4-DNT biodegradation. However, the mixed bacterial culture still effectively degraded 2,4-DNT with only slightly lower rates under these unfavorable conditions, thus showing potential for the remediation of 2,4-DNT contaminated sites.     

Use of microemulsions for removal of color and dyes from textile wastewater

One of the major environmental problems in the textile dyeing industry is the removal of color from effluents. The present study deals with color removal from effluents using microemulsions. The wastewater used in this study was the reactive exhausted dye liquor from a dyeing house containing Procion Yellow H‐E4R (CI Reactive Yellow 84), Procion Blue H‐ERD (CI Reactive Blue 160) and Procion Red H‐E3B (CI Reactive Red 120). Color removal was determined by CIE L*a*b* (CIELAB) color space, CIE L*a*b* color difference, ΔE*_ab, and absorbance. Color removal greater than 95% was achieved, attaining values lower than the consent requirements established by the Environmental Agency. It was observed that pH is an important parameter in color removal and effluent pH correction from 10.44 to 9 before extraction improved results. The results obtained were modeled using the Scheffé net method and evaluated through the construction of isoresponse diagrams by correlation graphics between experimental values and those obtained through use of model equations, providing an experimental error of less than 2%. The optimized method very efficiently removed all dyes contained in the effluent. The same microemulsion phase recovered after the extraction process can be used at least a further 14 times and all the extractions gave good color removal. Copyright © 2004 Society of Chemical Industry     

Effect of alkylaluminum structure on Ziegler-Natta catalyst systems based on neodymium for producing high-cis polybutadiene

Summary  In this work, a laboratory scale process for producing polybutadiene with high content of cis-1,4 repeating units was studied. A Ziegler-Natta catalyst system constituted of neodymium versatate (catalyst), an alkylaluminum compound (alkylating agent and cocatalyst) and tert-butyl chloride (chlorinating agent) was used. The solvent employed was a mixture of hexane and cyclohexane (80/20 v/v). The objective of this work was to evaluate the effect of alkylaluminum structure and the influence of Al/Nd (5 to 15) molar ratio of long chain alkylaluminium compound (tri(n-hexyl)aluminum) on catalyst activity and polybutadiene characteristics. The alkylaluminum compounds employed in this study were tri(i-butyl)aluminum, tri(n-hexyl)aluminum, tri(n-octyl)aluminum and di(i-butyl)aluminum hydride. The polybutadienes molar masses obtained were strongly influenced by the alkylaluminum structure. Polymers with the highest molar masses were obtained when tri(i-butyl)aluminum, tri(n-hexyl)aluminum and tri(n-octyl)aluminum were employed. However, polymers with the highest contents of cis-1,4 units and the lowest molar masses were produced when di(i-butyl)aluminum hydride was employed.     

The effect of composition of a polymeric coating on the biofilm formation of bacteria and filamentous fungi

Functionality of polymeric coating, especially in terms of anti-corrosive properties and stability, can be negatively influenced by formation of either bacterial or fungal biofilm on its surface. Herein, the epoxy-ester resin based polymeric coating was filled with pigments (natural silicon dioxide diatomite, natural wollastonite, tungstate and molybdate). Pigments was modified by conducting polymers (polyaniline phosphate, polypyrrole phosphate, poly(p-phenylenediamine) phosphate and ZnFe₂O₄). Impact of modified pigments on the surface energy and formation of biofilm were tested. The use of various biofilm forming species of both the bacteria and fungi filled a knowledge gap about their behavior on polymeric coatings.     

Mesenchymal Stromal Cell Therapy in Novel Porcine Model of Diffuse Liver Damage Induced by Repeated Biliary Obstruction

In liver surgery, biliary obstruction can lead to secondary biliary cirrhosis, a life-threatening disease with liver transplantation as the only curative treatment option. Mesenchymal stromal cells (MSC) have been shown to improve liver function in both acute and chronic liver disease models. This study evaluated the effect of allogenic MSC transplantation in a large animal model of repeated biliary obstruction followed by partial hepatectomy. MSC transplantation supported the growth of regenerated liver tissue after 14 days (MSC group, n = 10: from 1087 ± 108 (0 h) to 1243 ± 92 mL (14 days); control group, n = 11: from 1080 ± 95 (0 h) to 1100 ± 105 mL (14 days), p = 0.016), with a lower volume fraction of hepatocytes in regenerated liver tissue compared to resected liver tissue (59.5 ± 10.2% vs. 70.2 ± 5.6%, p < 0.05). Volume fraction of connective tissue, blood vessels and bile vessels in regenerated liver tissue, serum levels of liver enzymes (AST, ALT, ALP and GGT) and liver metabolites (albumin, bilirubin, urea and creatinine), as well as plasma levels of IL-6, IL-8, TNF-α and TGF-β, were not affected by MSC transplantation. In our novel, large animal (pig) model of repeated biliary obstruction followed by partial hepatectomy, MSC transplantation promoted growth of liver tissue without any effect on liver function. This study underscores the importance of translating results between small and large animal models as well as the careful translation of results from animal model into human medicine.     

Ordinary Gasoline Emissions Induce a Toxic Response in Bronchial Cells Grown at Air-Liquid Interface

Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes.     

Poisson’s ratio of porous and cellular materials with randomly distributed isometric pores or cells

The porosity dependence of Poisson's ratio of materials with random microstructure is investigated via analytical and numerical modeling. It is shown that all analytical models predict porosity independence if the solid Poisson ratio is 0.2 and for low porosities a converging trend toward this value with increasing porosity. From all theory-based relations, only power-law and exponential relations allow for auxetic behavior. Numerical calculations on computer-generated digital microstructures (overlapping and isolated spherical pores, pores between overlapping spherical grains, wall-based cellular materials/closed-cell foams, and strut-based cellular materials/open-cell foams) confirm the general qualitative trends of the analytical models, although a closer look reveals significant quantitative differences. Cellular materials and foams exhibit similar features as porous materials in general, but lack their converging trend toward values around 0.2. Comparison of our results with the classical Roberts-Garboczi results shows good agreement, with subtle differences due to the different microstructures generated.     

Preparation and evaluation of inclusion complexes of commercial sunscreens in cyclodextrins and montmorillonites: performance and substantivity studies

Herein we describe inclusion complexes of commercial sunscreens in cyclodextrins and montmorillonites to generate new sunscreen derivatives with optimized functional properties such as water resistance and skin adherence. Four cyclodextrins (alpha-, beta-, and gamma-cyclodextrin, and beta-dimethyl cyclodextrin) and two montmorillonites (sodium and alkylammonium) were investigated for encapsulating some commercial sunscreens. Our results reveal a good yield and inclusion products with functional properties obtained by using kneading technique on Eusolex 2292 and Eusolex 6007 in beta-cyclodextrin and solubilization method on Eusolex 6007 and NeoHeliopan MA in montmorillonite. In addition, molecular modeling studies indicated flexibility as important for the intercalation of the host molecule.