Volume 66, Issue 11

Biological molecules such as enzymes, cells, antibodies, lectins, peptide aptamers, and cellular components in an immobilized form are extensively used in biotechnology, in biorecognition and in many medicinal applications. This review provides a comprehensive summary of the developments in new immobilization materials, techniques, and their practical applications previously developed by the authors. A detailed overview of several immobilization materials and technologies is given here, including bead cellulose, encapsulation in ionotropic gels and polyelectrolyte complexes, and various immobilization protocols applied onto surfaces. In addition, the review summarises the screening and design of an immobilization protocol, practical applications of immobilized biocatalysts in the industrial production of metabolites, monitoring, and control of fermentation processes, preparation of electrochemical/optical biosensors and biofuel cells.

Network and numerical analysis of permeation through a membrane under non-stationary, stationary, and pseudo-stationary conditions is described. A compartmentalized membrane system (feed solution|membrane|stripping solution) was represented by a linear network of capacitances, diffusion, and sorption/desorption graphs. Reticulation degree of diffusion layers sufficient for quantitative modeling of the diffusion through a homogeneous membrane was estimated. It was found that for membranes of the thickness from 0.001 cm to 0.1 cm and the diffusion coefficients from 1 × 10−7 cm2 s−1 to 1 × 10−5 cm2 s−1, the membrane (or other diffusion layer) partition into ten slices leads to simulated time lags and stationary fluxes differing from the theoretical ones by less than 0.5 % and 1 %, respectively. Extended model with two unstirred interfacial layers and the feed and stripping solution of finite volumes was applied to characterize the effects caused by possible membrane heterogeneity.

Using the simulation program CHEMCAD, performance characteristics, design optimization, and costs of an absorption/stripping system used to purify 100 kg h−1 of biogas in a biogas power plant were investigated. Potential absorbents used in the chemical absorption process were the following aqueous solutions: pure diglycolamine, diglycolamine/piperazine, and diglycolamine/methyldiethanolamine/piperazine. Mixtures for agricultural biogas purification to below 1 vol. % of CO2 and 4 × 10−4 mass % of H2S were determined via a simulation in the above mentioned program. The chosen mixtures were then entered into an absorption/desorption system and simulations for each unit were provided by CHEMCAD. From the simulation results, the design parameters were calculated and entered into each unit’s “cost estimation” section in the aforementioned program to estimate the purchase costs of the apparatuses. Taking into account the installation, maintenance, as well as other additional costs, the actual machine purchase costs were multiplied by the Lang factor. Costs of additional streams were also calculated by multiplying the ten-year utility losses by their respective cost factors. From these calculations, the absorbent mixture, allowing biogas production at the lowest estimated costs for ten years, was found.

The aim of this study was to investigate the pressure drop coefficient and the static pressure difference related to the natural vortex length and to evaluate the results for gas-particle applications. CFD simulations were carried out using a numerical technique which had been verified previously. Results obtained from the numerical simulations were compared with the experimental data. Analysis of the results showed that the pressure drop coefficient decreases with the increasing inlet velocity, becoming almost constant above a certain value of the inlet velocity. The reason is that the effect of viscous forces decreases at high Reynolds numbers. The pressure drop coefficient also decreases with the increasing exit pipe diameter and decreasing exit pipe length.

Metallic elements such as Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Rb, Sr, and Zn were determined using ICP-OES in a representative set of fifteen fruiting bodies of the edible fungus Suillus variegatus. Fruiting bodies were collected from unpolluted areas near the village of Lubichowo of the Bory Tucholskie forest complex in northern Poland in 2007–2008. The caps were richer in Ag, Al, Cd, Cr, Cu, Fe, K,Mg, Ni, Rb, and Zn, and the stipes in Ba, Ca, Mn, Na, Pb, and Sr. Cobalt concentration in the caps and stipes was similar. In the caps, the content of the elements decreased in the order (mg per kg of dry weight): K 29000 ± 3700, Fe 1600 ± 80, Mg 990 ± 110, Rb 320 ± 86, Zn 90 ± 19, Ca 75 ± 34, Al 68 ± 32, Na 40 ± 18, Cu 19 ± 7, Mn 13 ± 7, Cd 1.0 ± 0.5, Ni 0.64 ± 0.32, Ag 0.40 ± 0.20, Cr 0.33 ± 0.06, Pb 0.20 ± 0.17, Ba 0.19 ± 0.11, Sr 0.15 ± 0.09, and Co 0.070 ± 0.050. Apparently, S. variegatus collected from background areas are relatively low in Pb and Cd and so are suitable for human consumption.

The highly insoluble organic-inorganic hybrid ionic compounds N,N′-methylenedipyridinium tetrachloroplatinate(II) [(C5H5N)2CH2] · [PtCl4] and N,N′-methylenedipyridinium hexachloroplatinate(IV) [(C5H5N)2CH2] · [PtCl6] were obtained by the treatment of N,N′-methylenedipyridinium dichloride monohydrate [(C5H5N)2CH2]Cl2 · H2O with K2[PtCl4] or (NH4)2[PtCl6], respectively, in an aqueous solution. Both complexes were isolated, purified, characterised by elemental analysis, and their molecular structures were confirmed by powder X-ray diffraction. The crystal structure of both compounds consists of separated discrete dications [(C5H5N)2CH2]2+ and anions [PtCln]2− (n = 4 or 6). As anticipated, the dications formed a butterfly shape consisting of two pyridine rings bound to the methylene group via their N atoms, while the Pt centre had a square planar geometry in [(C5H5N)2CH2] · [PtCl4] and an octahedral coordination in [(C5H5N)2CH2] · [PtCl6]. Interestingly, both crystal structures are stabilised by intermolecular C-H…Cl non-standard hydrogen bonds, π-π ring interactions between two pyridine rings of adjacent dications, and also by Cl-π interactions.

The presented study provides a possibility to create ultrafiltration (UF), polyacrylonitrile(PAN)/butadiene-acrylonitrile elastomer (BNR)/N,N-dimethylformamide (DMF) membranes. Influence of different concentrations of the elastomer on the formation of a more porous structure was studied and compared with that observed using membranes made of polyacrylonitrile. Specific influence of copper ions in a solution of polymers on the formation of an asymmetric selective layer was also monitored. The study was conducted to prepare membranes with high efficiency in emulsion and colloidal systems separation.

A one-pot method was employed to immobilize sulfonic acid onto silica obtained from rice husk ash using 3-(mercaptopropyl)trimethoxysilane to form a solid catalyst denoted as RHASO3H. BET measurements of the catalyst showed the surface area to be 340 m2 g−1 with the average pore volume of 0.24 mL g−1 and the pore diameter of 2.9 nm. Acidity test of cation exchange capacity and pyridine adsorption studies revealed the presence of Brønsted acid sites on the catalyst surface. The catalyst was used in the acetalization reaction of glycerol with benzaldehyde. Under optimized conditions, the reaction showed the maximum conversion of 78 % after 8 h with 67 % selectivity towards the five membered ring isomer. Variation in the glycerol concentration had a significant effect on the reactants conversion. A single crystal X-ray study of one of the products proved the existence of a unique trimer formed by hydrogen bonding by the six-membered cis-isomer. The catalyst was several times recycled without any loss of its catalytic activity.

Reaction mechanism of 1,1,1-trifluorotrichloroethane (CF3CCl3) and sulphur trioxide (SO3) in the presence of mercury salts (Hg2SO4 and HgSO4) was studied applying the density functional theory (DFT) at the UB3LYP/6-31+G(d,p) level. It was found that this reaction occurs in the free radical chain path as follows: mercury(I) sulphate free radical is generated by heat, causing CF3CCl3 to produce the CF3CCl2 free radical which reacts with SO3 leading to the formation of CF3CCl2OSO2 decomposing into CF3COCl and SO2Cl. The SO2Cl free radical triggers CF3CCl3 to regenerate CF3CCl2 which recycles the free radical growth reaction. This elementary reaction has the highest energy barrier and it is therefore the rate control step of the whole reaction path. Experiment data can confirm the existence of the mercury(I) salt free radical and the free radical initiation stage. So, mercury salts play the role of initiators not that of catalysts. The results agree well with our hypothesis.

Near-infrared (NIR) imaging systems simultaneously record spectral and spatial information. Near-infrared imaging was applied to the identification of (E,Z)-4-(3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)acryloyl)morpholine (dimethomorph) in both mixed samples and commercial formulation in this study. The distributions of technical dimethomorph and additive in the heterogeneous counterfeit product were obtained by the relationship imaging (RI) mode. Furthermore, a series of samples which consisted of different contents of uniformly distributed dimethomorph were prepared and three data cubes were generated for each content. The spectra extracted from these images were imported to establish the partial least squares model. The model’s evaluating indicators were: coefficient of determination (R 2) 99.42 %, root mean square error of calibration (RMSEC) 0.02612, root mean square error of cross-validation (RMSECV) 0.01693, RMSECVmean 0.03577, relative standard error of prediction (RSEP) 0.01999, and residual predictive deviation (RPD) 15.14. Relative error of prediction of the commercial formulation was 0.077, indicating the predicted value correlated with the real content. The chemical value reconstruction image of dimethomorph formulation products was calculated by a MATLAB program. NIR microscopy imaging here manifests its potential in identifying the active component in the counterfeit pesticide and quantifying the active component in its scanned image.

Pure and enriched titanium dibromide (TiB2) samples (prepared by hot isostatic pressing) with different mole ratios of Ni and Ta were investigated in contact with molten eutectic salt (FLiNaK(eut); LiF/NaF/KF 42.5 mole %: 11.5 mole %: 42.0 mole %) at 600°C. Corrosion resistance of the materials was studied, the mass losses and depths of corrosion were calculated, and sample surfaces were investigated by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX). Nickel addition decreased the corrosion resistance of TiB2. Simultaneous additions of both elements, Ni and Ta, as well as the addition of Ta only showed reducing effect on grain formation and they increased the corrosion resistance which is highest in the last case.

The efficient synthesis of 4-substituted 5-thioxo-1,2,4-triazolidin-3-one derivatives (4-substituted thiourazoles) via domino combination of thiophosgene, aliphatic or aromatic amines, and ethyl carbazate is presented.