Bioreduction of ionic mercury from wastewater in a fixed-bed bioreactor with activated carbon

Wide industrial use of mercury led to significant mercury pollution of the environment. It requires development of cleanup technologies which would allow treating large volumes of mercury contaminated water in a cost effective and environmentally friendly way. A novel bio-technology, developed from laboratory to industrial scale in Germany at HZI (former GBF), is based on enzymatic reduction of highly toxic Hg(II) to water-insoluble and relatively non-toxic Hg(0) using live mercury resistant bacteria immobilized on a porous carrier material in a fixed-bed bioreactor. Improvement of the original method was based on the use of activated carbon as a carrier for microorganisms and an adsorbent for mercury. Such integration of the process should increase the technology efficiency. In order to compare different carrier materials, activated carbon and pumice stones were used. The strain Pseudomonas putida was immobilized in bioreactors continuously fed with solutions of HgCl₂ enriched with nutrients. Simultaneously, experiments in two more reactors were run in the absence of microorganisms to investigate the influence of nutrients on the adsorption process. In the bioreactor with activated carbon, the outlet mercury concentration was approximately 50 % of that supplied with pumice. It may be concluded that the use of activated carbon in a fixed-bed bioreactor enables improvement of the technology by process integration. Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May 2007.     

Application of molecular dynamics computer simulations in the design of a minimal self‐replicating molecular machine

It is commonly agreed that a chemical assembly of molecules can be considered alive if it can ingest resources and convert them into building blocks; has the ability to grow and self‐reproduce; and can evolve. In the design proposed by Rasmussen and Chen (Science 2004, 303, 963) the assembly or protocell could be as simple as a small micellar surfactant aggregate acting as a container, anchoring an informational molecule to its exterior and incorporating a metabolism within the oily interior. We present several examples of modeling such a system with molecular dynamics computer simulations. © 2008 Wiley Periodicals, Inc. Complexity, 2008.     

Light elementary pseudoscalars within the framework of effective lagrangians

The total, effective, low energy lagrangian for K→π+ pseudoscalar decays has been derived for any model involving light elementary pseudoscalars. As an illustration, branching ratios for those decays have been calculated for a two-Higgs doublet model in which only one Higgs doublet couples to quarks. Experimentally allowed regions in the parameter space have been found.     

Synthesis and structure of poly(ε-caprolactone)/synthetic montmorillonite nano-intercalates

Bulk polymerisations of ε-caprolactone (CL) were conducted at 170 °C in the presence of catalytic traces of water and 10, 30 and 50 wt% of hydrated synthetic montmorillonite SOMASIF ME100 (M) without additional catalysts. In both cases a low molecular poly(ε-caprolactone) (PCL) was produced (M_w = 5360-22,432). As revealed by ¹H NMR and GPC analyses the montmorillonite present in the system induced both significantly higher lactone hydrolysis and polymer chain growth rates. Wide-angle X-ray scattering (WAXS) technique was applied to investigate the changes in clay stratification after swelling with monomer and after the polymerisation. The scattering peaks from clay (0 0 1) periodicity recorded for the silicate in dispersions and in the composites are shifted towards lower angles, which indicate an intercalation of CL as well as PCL in the galleries. Narrow intensity distribution of Bragg peaks recorded for both CL/M mixtures and resulting nano-intercalates testifies that the well ordered, layered structure of montmorillonite is retained in the silicate swollen with ε-caprolactone and after the polymerisation. The results suggest that PCL chains are flatly arranged onto each side of silicate platelet and they create pseudo-bilayers inside the silicate’s gallery.     

Improved TLC Detection of Prostaglandins by Post-Run Derivatization with Phosphomolybdic Acid

JPC – Journal of Planar Chromatography – Modern TLC -     

On the hardness of evaluating criticality of activities in a planar network with duration intervals

Complexity results for problems of evaluating the criticality of activities in planar networks with duration time intervals are presented. We show that the problems of asserting whether an activity is possibly critical, and of computing bounds on the float of an activity in these networks are NP-complete and NP-hard, respectively.