Toxic Chemical and their Neutralising Agents in Porous Media

The UK Government Decontamination Service advises central Govern- ment on the national capability for the decontamination of buildings, infrastructure, transport and open environment, and be a source of expertise in the event of a chemical, biological, radiological and nuclear (CBRN) incident or major release of HazMat materials. The study group constructed mathematical models to describe the depth to which a toxic chemical may seep into an initially dry porous substrate, and of the neutralisation process between a decontaminant and the imbibed chemical. The group recognised that capillary suction was the dominant process by which the contaminant spreads in the porous substrate. Therefore, in the first instance the absorption of the contaminant was modelled using Darcy’s law. At the next level of complication a diffuse interface model based on Richards’ equation was employed. The results of the two models were found to agree at early times, while at later times we found that the diffuse interface model predicted the more realistic scenario in which the contaminant has seeped deeper into the substrate even in the absence of further contaminant being supplied at the surface. The decontamination process was modelled in two cases; first, where the product of the decontamination reaction was water soluble, and the second where the reaction product formed soluble in the contaminant phase and of similar density. These simple models helped explain some of the key physics involved in the process, and how the decontamination process might be optimised. We found that decontamination was most effective in the first of these two cases. The group then sought to incorporate hydrodynamic effects into the reaction model. In the long wavelength limit, the governing equations reduced to a one-dimensional Stefan model similar to the one considered earlier. More detailed approximations and numerical simulations of this model were beyond the scope of this study group, but provide an entry point for future research in this area

Multiscale modeling of a rectifying bipolar nanopore : comparing Poisson-Nernst-Planck to Monte Carlo

In the framework of a multiscale modeling approach, we present a systematic study of a bipolar rectifying nanopore using a continuum and a particle simulation method. The common ground in the two methods is the application of the Nernst-Planck (NP) equation to compute ion transport in the framework of the implicit-water electrolyte model. The difference is that the Poisson-Boltzmann theory is used in the Poisson-Nernst-Planck (PNP) approach, while the Local Equilibrium Monte Carlo (LEMC) method is used in the particle simulation approach (NP+LEMC) to relate the concentration profile to the electrochemical potential profile. Since we consider a bipolar pore which is short and narrow, we perform simulations using two-dimensional PNP. In addition, results of a non-linear version of PNP that takes crowding of ions into account are shown. We observe that the mean field approximation applied in PNP is appropriate to reproduce the basic behavior of the bipolar nanopore (e.g., rectification) for varying parameters of the system (voltage, surface charge, electrolyte concentration, and pore radius). We present current data that characterize the nanopore’s behavior as a device, as well as concentration, electrical potential, and electrochemical potential profiles

Multiscale analysis of the effect of surface charge pattern on a nanopore’s rectification and selectivity properties: From all-atom model to Poisson-Nernst-Planck

We report a multiscale modeling study for charged cylindrical nanopores using three modeling levels that include (1) an all-atom explicit-water model studied with molecular dynamics, and reduced models with implicit water containing (2) hard-sphere ions studied with the Local Equilibrium Monte Carlo simulation method (computing ionic correlations accurately), and (3) point ions studied with Poisson-Nernst-Planck theory (mean-field approximation). We show that reduced models are able to reproduce device functions (rectification and selectivity) for a wide variety of charge patterns, that is, reduced models are useful in understanding the mesoscale physics of the device (i.e., how the current is produced). We also analyze the relationship of the reduced implicit-water models with the explicit-water model and show that diffusion coefficients in the reduced models can be used as adjustable parameters with which the results of the explicit- and implicit-water models can be related. We find that the values of the diffusion coefficients are sensitive to the net charge of the pore but are relatively transferable to different voltages and charge patterns with the same total charge

Environmental and recombinant microorganisms for biopharmaceuticals production

Current, very fast development of genetic engineering and protein engineering (main segments of modern biotechnology) is a good way for commercially production of proteins, which benefit biopharmaceutical, the enzyme and agricultural industries. These products augment the fields of medicine, diagnostics, food, nutrition, detergents, textiles, leather, paper, pulp, polymers and plastics. Proteins with biopharmaceutical application are mainly clinical reagents, vaccines and drugs. During the last decade, the pharmaceutical biotechnology represents the fastest growing segment in the biotechnology sector. Production of recombinant proteins for use as pharmaceuticals, is a multi-billion dollar industry. One third of the biopharmaceuticals has come from microorganisms, such as Escherichia coli and yeast. The selection of expression systems depends on the size and biochemical status of proteins. Large proteins and proteins that require glycosylation are usually expressed in a mammalian cells, fungi or the baculovirus system. Smaller proteins are produced by prokaryotic cells. There are some very useful advantages for prokaryotic recombinant expression systems: it is easy of culture, very rapid cell growth with possibility of IPTG expression induction and quite simple product purification. On the other hand, for very large proteins, for S-S rich proteins and proteins which require post-translational modifications, bacteria, usually E. coli strains are not robust system. Better are yeasts with very popular species Saccharomyces cerevisiae and Pichia pastoris. This article presents the current application of microbes as production platforms for recombinant proteins and its genetic engineering for the use as biopharmaceuticals

Specific for DNA damages GFP microbial biosensor as a tool for genotoxic action assessment of environmental pollution

In the presented paper, autofluorescent reporter of Escherichia coli K-12 recA::gfpmut2 strain, which contained a plasmid-borne transcriptional fusion between DNA-damage inducible recA promoter involved in the SOS regulon response and fast folding GFP variant reporter gene-gfpmut2, have been used. GFP-based bacterial biosensors allowed the detection of bacterial cells response to selected tested genotoxic compounds such as mitomycin C (MMC), actinomycin D, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and formaldehyde (CH2O). Experiment indicated that E. coli K-12 recA::gfpmut2 biosensor strain is more specific and sensitive for especially two genotoxins: actinomycin D and MNNG and with very low response to other agents. So it was concluded that for formaldehyde and MMC E. coli K-12 recA::gfpmut2 genetic system is disqualified for genotoxicity screening

Characteristics of the phenomenon of quorum sensing and its meaning in terms of formation and functioning of biofilm in environmental engineering, civil engineering, medicine and household

Na podstawie przeglądu literatury dokonano charakterystyki zjawiska quorum sensing, które w znaczeniu dosłownym oznacza poczucie obecności i odgrywa znaczącą rolę w procesie formowania i funkcjonowania biofilmu. Zjawisko to jest specyficznym systemem komunikacji pomiędzy drobnoustrojami z udziałem związków chemicznych, ściśle kontrolowanym przez określone geny w odpowiedzi na liczebność populacji drobnoustrojów. Biofilm odpowiada często za uszkodzenia urządzeń sanitarnych, gospodarstwa domowego, materiałów budowlanych. Poznanie mechanizmów tworzenia i funkcjonowania biofilmu pozwoli na opracowanie skuteczniejszych technologii walki ze skutkami jego szkodliwego oddziaływania w inżynierii środowiska, budownictwie jak również w codziennym życiu człowieka.In the paper characteristics of phenomenon of quorum sensing on base of current literature was done. Quorum sensing means sense of presence in literal meaning and it plays significant role in process of formation and functioning of biofilm. Quorum sensing is a special kind of communication system between microorganism with participation of chemicals. It is controlled by definite genes in answer on numerical force of population of microorganisms. Biofilm functioning is strictly connected with damages of sanitary equipment, housekeeping, construction materials. Knowledge of mechanism of biofilm creation will allow for elaboration of forceful technology of battle with its result of harmful interaction in environmental engineering, construction as well as in daily life of person