Behavior of two-chamber microbial electrochemical systems started-up with different ion-exchange membrane separators.

In this study, microbial fuel cells (MFCs) - operated with novel cation- and anion-exchange membranes, in particular AN-VPA 60 (CEM) and PSEBS DABCO (AEM) - were assessed comparatively with Nafion proton exchange membrane (PEM). The process characterization involved versatile electrochemical (polarization, electrochemical impedance spectroscopy - EIS, cyclic voltammetry - CV) and biological (microbial structure analysis) methods in order to reveal the influence of membrane-type during start-up. In fact, the use of AEM led to 2-5 times higher energy yields than CEM and PEM and the lowest MFC internal resistance (148 ±â€¯17 Ω) by the end of start-up. Regardless of the membrane-type, Geobacter was dominantly enriched on all anodes. Besides, CV and EIS measurements implied higher anode surface coverage of redox compounds for MFCs and lower membrane resistance with AEM, respectively. As a result, AEM based on PSEBS DABCO could be found as a promising material to substitute Nafion.

A review of the innovative gas separation membrane bioreactor with mechanisms for integrated production and purification of biohydrogen.

This review article focuses on an assessment of the innovative Gas Separation Membrane Bioreactor (GS-MBR), which is an emerging technology because of its potential for in-situ biohydrogen production and separation. The GS-MBR, as a special membrane bioreactor, enriches CO2 directly from the headspace of the anaerobic H2 fermentation process. CO2 can be fed as a substrate to auxiliary photo-bioreactors to grow microalgae as a promising raw material for biocatalyzed, dark fermentative H2-evolution. Overall, these features make the GS-MBR worthy of study. To the best of the authors' knowledge, the GS-MBR has not been studied in detail to date; hence, a comprehensive review of this topic will be useful to the scientific community.

Improved Hydrogen Separation Using Hybrid Membrane Composed of Nanodiamonds and P84 Copolyimide.

Membrane gas separation is a prospective technology for hydrogen separation from various refinery and petrochemical process streams. To improve efficiency of gas separation, a novel hybrid membrane consisting of nanodiamonds and P84 copolyimide is developed. The particularities of the hybrid membrane structure, physicochemical, and gas transport properties were studied by comparison with that of pure P84 membrane. The gas permeability of H2, CO2, and CH4 through the hybrid membrane is lower than through the unmodified membrane, whereas ideal selectivity in separation of H2/CO2, H2/CH4, and CO2/CH4 gas pairs is higher for the hybrid membrane. Correlation analysis of diffusion and solubility coefficients confirms the reliability of the gas permeability results. The position of P84/ND membrane is among the most selective membranes on the Robeson diagram for H2/CH4 gas pair.

D-mannose-modified iron oxide nanoparticles for stem cell labeling.

New surface-modified iron oxide nanoparticles were developed by precipitation of Fe(II) and Fe(III) salts with ammonium hydroxide according to two methods. In the first method, precipitation was done in the presence of D-mannose solution (in situ coating); the second method involved oxidation of precipitated magnetite with sodium hypochlorite followed by addition of D-mannose solution (postsynthesis coating). Selected nanoparticles were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), elemental analysis, dynamic light scattering, infrared (IR), X-ray powder analysis, and ultrasonic spectrometry. While the first preparation method produced very fine nanoparticles ca. 2 nm in diameter, the second one yielded ca. 6 nm particles. Addition of D-mannose after synthesis did not affect the iron oxide particle size. UV-vis spectroscopy suggested that D-mannose suppresses the nonspecific sorption of serum proteins from DMEM culture medium on magnetic nanoparticles. Rat bone marrow stromal cells (rMSCs) were labeled with uncoated and d-mannose-modified iron oxide nanoparticles and with Endorem (Guerbet, France; control). Optical and transmission electron microscopy confirmed the presence of D-mannose-modified iron oxide nanoparticles inside the cells. D-mannose-modified nanoparticles crossed the cell membranes and were internalized well by the cells. Relaxivity measurements of labeled cells in gelatin revealed very high relaxivities only for postsynthesis D-mannose-coated iron oxide nanoparticles.

Surface immobilized protein multilayers for cell seeding.

Multilayer assemblies containing various cell-adhesive proteins such as gelatin, collagen IV, and laminin or polycations polylysine and poly(ethyleneimine) were immobilized on the polystyrene surface using the layer-by-layer technique based on hydrophobic and electrostatic interactions between oppositely charged macromolecules. The formation and stability of the assemblies and the adsorption of proteins from a serum containing cell-cultivation media onto their surfaces were observed in real time by Fourier transform infrared multiple internal reflection spectroscopy. The adhesion and growth of mouse embryonic stem cells line D3 were tested in polystyrene culture dishes coated with the assemblies. The cells were seeded in complete serum-containing media or in serum-free media and in the presence (non-differentiated) and/or absence (differentiated) of leukemia inhibitory factor. Proteins from serum-containing cell-cultivation media adsorbed rapidly onto positively charged surfaces. The cells grew best on surfaces coated with gelatin and collagen IV assemblies. There were no significant differences in the growth of the non-differentiated and differentiated cells in complete serum-containing media. When seeded in serum-free media, non-differentiated cells grew better than the differentiated ones. Particularly, polycation surfaces treated with glutaraldehyde promoted the growth of the non-differentiated cells and hindered the growth of the differentiated cells. The layer-by-layer deposition appears to be a practicable technique by which scaffolds for tissue engineering can be coated with biomolecular assemblies tailored to specific cells and applications.