The determination of parameters of multi-step adsorption isotherm by sequential simplex optimization

The determination of parameters of Multi-Step Adsorption Isotherm by Sequential Simplex optimization Tolner László Department for Soil Science and Agricultural Chemistry, Szent István University Pater Karoly street, H-2103 Gödöllő, Hungary (phone: +36-30-581-0327; fax: +36-28-522-081) [email protected] Abstract. The nutrient and toxic compounds can be adsorbed on the surface of soil colloids. Investigating the adsorption of some pesticide compounds, instead of the simply asymptotic Langmuir isotherm multi-step isotherms can be obtained. In these cases a new layer is formed after the surface saturation, however, this mechanism can be described by using a new Langmuir-type isotherm. The adsorption of some compounds led to three superposition steps. The mathematical form is a nonlinear function with 8 parameters. The parameters were determined by a robust, direct optimum searching subroutine carried out by Visual basic macro made in Excel spreadsheet program which uses a simplex stepping procedure. The aim of the optimization is to minimize the residual sum of squares between measured and calculated values. The aim function can be calculated for any parameter series in the adequate dimension number. During the iteration the residual sum of squares decreases step by step, while the differences will be negligible. Keywords: Regression; Model; Adsorption; Pesticide; Soi

Domestication and Proliferation of Algae Cultures for Boosting Efficiency of Waste-water Treatment through Symbiosis

Native algae strains have been domesticated and stimulated in activated sludge wastewater treatment operations. The term of domestication indicates that we did not add any selected algae to the wastewater, but made use of species existing in the system. The term of proliferation indicates a stimulation of the biological oxidation process by provision of CO2 with the air stream and illumination of the reactor. The idea of domestication of algae present in communal wastewater systems was demonstrated. Stimulation of the system with domesticated algae community did improve efficiency of the treatment process. Removal of organic components in terms of reduction of chemical and biological oxidation demands (dissolved COD, BOD) as well as nitrogen and phosphorous contents was superior to extent of removal in conventional activated sludge system. We did conclude that conventional systems lack available light and carbon resources for these microorganisms. Upon providing these, symbiotic operation can contribute to reducing greenhouse gas emissions and increase of the rate of pollutants removal kinetics. Symbiotic operation increased the production of biomass expressed in terms of total suspended solids. Biodiesel potential of the filterable biomass was in the range of 8-18%. Because of technical difficulties in manipulation of the excess sludge other than biodiesel synthesis processing scheme has been recommended for economically viable processing

Purification and Reconstitution of the Glutamate Carrier GltT of the Thermophilic Bacterium Bacillus stearothermophilus

An affinity tag consisting of six adjacent histidine residues followed by an enterokinase cleavage site was genetically engineered at the N-terminus of the glutamate transport protein GltT of the thermophilic bacterium Bacillus stearothermophilus. The fusion protein was expressed in Escherichia coli and shown to transport glutamate. The highest levels of expression were observed in E. coli strain DH5α grown on rich medium. The protein could be purified in a single step by Ni2+-NTA affinity chromatography after solubilization of the cytoplasmic membranes with the detergent Triton X100. Purified GltT was reconstituted in an active state in liposomes prepared from E. coli phospholipids. The protein was reconstituted in detergent-treated preformed liposomes, followed by removal of the detergent with polystyrene beads. Active reconstitution was realized with a wide range of Triton X100 concentrations. Neither the presence of glycerol, phospholipids, nor substrates of the transporter was necessary during the purification and reconstitution procedure to keep the enzyme in an active state. In B. stearothermophilus, GltT translocates glutamate in symport with protons or sodium ions. In membrane vesicles derived from E. coli cells expressing GltT, the Na+ ion dependency seems to be lost, suggesting a role for the lipid environment in the cation specificity. In agreement with the last observation, glutamate transport catalyzed by purified GltT reconstituted in E. coli phospholipid is driven by an electrochemical gradient of H+ but not of Na+.

Adaptation of microorganisms and their transport systems to high temperatures

Growth of Bacteria and Archaea has been observed at temperatures up to 95 and 110 degrees C, respectively. These thermophiles are adapted to environments of high temperature by changes in the membrane lipid composition, higher thermostabilities of the (membrane) proteins, higher turnover rates of the energy transducing enzymes, and/or the (exclusive) use of sodium-ions rather than protons as coupling ion in energy transduction. The proton permeability of the cytoplasmic membrane of bacteria and archaea was observed to increase with the temperature. This increased proton permeability limits the maximum temperature of growth of bacteria. Higher growth temperatures can be reached by an increased proton pumping activity by using the less permeable sodium ions as coupling ions or by changing the lipid composition of the cytoplasmic membrane. The Na+/H+/glutamate transport proteins of the thermophiles Bacillus stearothermophilus (GltT(Bc)) and Bacillus caldotenax (GltT(Bc)) were studied extensively. These transportproteins have unique features. Transport of L-glutamate occurs in symport with 1 Na+ and 1 H+ when the transport proteins are expressed in their natural environment. The sodium ion dependency of the GltT transporters of these Bacillus strains was found to increase with temperature. However, when the GltT proteins are expressed in the mesophile Escherichia coli, electrogenic symport of L-glutamate occurs with greater than or equal to 2 H+. These observations suggest that the conformation of the transport proteins in the E. coli and the Bacillus membranes differs, and that the conformation influences the coupling ion selectivity. The Na+/H+/glutamate transport proteins of B. stearothermophilus (GltT(Bc)) and B. caldotenax (GltT(Bc)) are homologous to transport systems of glutamate and structurally related compounds from mesophilic organisms. Both sodium, as well as proton coupled transporters, belong to this family of carboxylate transporters (FCT). (C) 1997 Elsevier Science Inc

Characterization and functional expression in Escherichia coli of the sodium/proton/glutamate symport proteins of Bacillus stearothermophilus and Bacillus caldotenax

The genes encoding the Na+/H+/L-glutamate symport proteins of the thermophilic organisms Bacillus stearothermophilus (gltT(Bs)) and Bacillus caldotenax (gltT(Bc)) were cloned by complementation of Escherichia coli JC5412 for growth on glutamate as sole source of carbon, energy and nitrogen. The nucleotide sequences of the gltT(Bs) and gltT(Bc), genes were determined. In both cases the translated sequences corresponded with proteins of 421 amino acid residues (96.7% amino acid identity between GltT(Bs) and GltT(Bc)). Putative promoter, terminator and ribosome-binding-site sequences were found in the flanking regions. These expression signals were functional in E coli. The hydropathy profiles indicate that the proteins are hydrophobic and could form 12 membrane-spanning regions. The Na+/H+ CoUpled L-glutamate symport proteins GltT(Bs) and GltT(Bc) are homologous to the strictly H+ coupled L-glutamate transport protein of E. coli K-12 (overall 57.2% identity). Functional expression of glutamate transport activity was demonstrated by uptake of glutamate in whole cells and membrane vesicles. In accordance with previous observations (de Vrij et al., 1989; Heyne et al., 1991), glutamate uptake was driven by the electrochemical gradients of sodium ions and protons

Új szemcseméret eloszlás vizsgálat kidolgozása az eltérő módszerek harmonizálásának érdekében = Development a new particle size distribution measurement technique in order to harmonizing the different methods

A kutatás célja egy olyan szemcse-eloszlás meghatározó berendezés kifejlesztése volt a célunk, amely a korábbinál nagyobb mérési pontosságú és mérési gyakoriságú, automatikusan üzemeltethető, párhuzamosan elvileg tetszőleges számú agyag-iszap minta vizsgálatára alkalmas, egyben a méréshez kapcsolódóan a dokumentáció is azonnal elkészíthető. A fenti probléma megoldására végül megszületett az elektronikus areométer. Ez egy olyan areométer, melynek nyakában egy vezető réteg helyezkedik el, ez az egyik fegyverzet, a másik fegyverzet a talajszemcséket tartalmazó oldat, melynek magassága, és ezzel a kondenzátor kapacitása változik az ülepedés során. Az areométer besüllyedését azaz a sűrűség csökkenésének időfüggését mérjük közvetlenül. A sűrűség csökkenést az adott időpillanatban már kiülepedett, azaz a mérőcső szintje alá süllyedt részecskék vizsgált térfogatból való eltávozása okozza. Ebből elméleti megfontolásokat alkalmazva kidolgoztuk a szemcseméret eloszlás számítására alkalmas véges érintők (FIT) módszerét. A készített berendezés validálásának érdekében négy tipikus magyar talajtípust használtunk, melyeknek fizikai félesége különbözött egymástól. Kimutattuk, hogy nincs szignifikáns eltérés két alkalmazott eljárással kapott eredmények között, kivéve a 0,05 mm frakciót. Ez azt jelenti, hogy a két módszer a vizsgált frakciókban egymással egyenértékű, így egymást helyettesítheti a vizsgálatok során. | To continuously measurement of PSD we worked out an digital areometer. The device is equipped a capacitive sensors on the neck of the areometer, which can measure the changes of water levels nearby the neck of the areometer in 10 ?m precision with <1 ?m errors. The typical level changes are 3-5 cm, The measured signals are stored in the memory of equipment and after the end of measurement the database is downloaded to the to the controller computer. Because the whole system can be managed as the aggregation of many mono-disperse systems, it is possible to divide the measured density-time function into grain-size fractions with tangent lines drawn to finite but optional points. For calculating the settling speed of given fraction, these tangent lines are very good tools, because the changing speed of density is equal to the multiplication of settling speed and mass of given fraction. The aim of validate research is to test and validate a developed automated continuous particle size method.The particle size of these samples was measured by both the conventional pipette method and the automated method. Based on statistical analysis the results of used pipette method and continuous aerometer method at used soil samples, give statistically equal results in the average and all fraction except the 0,05 mm fraction. It means the continuous areometer method compatible with conventional method