Monitoring of monosaccharides,oligosaccharides, ethanol and glycerol during wort fermentation by biosensors,HPLC and spectrophotometry

The aim of the present study was to analyze sugar levels (namely maltose, maltotriose, glucose and fructose) and alcohols (ethanol and glycerol) during the fermentation process in wort samples by amperometric enzymatic biosensors developed by our research group for industrial application, HPLC and spectrophotometry, and to compare the suitability of the presented methods for determination of individual analytes. We can conclude that for the specific monitoring of maltose or maltotriose only the HPLC method was suitable. On the other hand, biosensors and spectrophotometry reflected a decrease in total sugar concentration better and were able to detect both glucose and fructose in the later stages of fermentation, while HPLC was not. This can be attributed to the low detection limits and good sensitivity of the proposed methods. For the ethanol and glycerol analysis all methods proved to be suitable. However, concerning the cost expenses and time analysis, biosensors represented the best option.     

Macerals in bituminous coals and the coking process: Part 1: Effect of basic coal properties on the process of thermal degradation

Bituminous coals produced in the Ostrava—Karviná coal basin show considerable variation in their maceral composition and rank. In order to explain the significance of the petrographic composition, structure and chemical parameters in coal degradation processes, a large number of coal samples was investigated. From the relationships obtained, the behaviour of macerals during these processes is discussed. It is found that isometamorphic vitrinites are characterized by a distinctive behaviour affected to a first approximation by the atomic ratios C/H and C/O. Inertinite, despite its occasional significantly higher volatile matter, does not yield an appreciable amount of fused material.     

Changes of hydrogen peroxide and radical-scavenging activity of raspberry during osmotic, convective, and freeze-drying

This study was conducted to investigate the influence of different drying treatments on antioxidant (AO) activity and phenolic content of raspberry (Rubus idaeus), cultivar Willamette. Whole raspberry fruits were dried convectively (air-drying), osmotically, and freeze-dried. Acetone-water extracts of fresh and dried raspberries were assessed for total phenolic content by standard Folin-Ciocalteau method. Two AO assays were applied, a recently developed direct current (DC) polarographic assay based on decrease of anodic oxidation current of hydrogen peroxide and widely used radical scavenge against the 1,1-diphenyl-2-picrylhydrazyl (DPPH). Strong correlation has been obtained between both AO assays and total phenolic content. In addition, some individual phenolic compounds present in raspberry have been assessed using DPPH and DC polarographic assay. Comparison and evaluation of drying methods has been based on preservation of AO activity and total phenolic content. Obtained results confirmed superiority of freeze-drying; convective drying caused slight changes while osmotic dehydration showed a significant decrease of phenolic compounds and AO activity.     

The Escherichia coli RecA protein complements recombination defective phenotype of the Saccharomyces cerevisiae rad52 mutant cells

The Saccharomyces cerevisiae rad52 mutants are sensitive to many DNA damaging agents, mainly to those that induce DNA double-strand breaks (DSBs). In the yeast, DSBs are repaired primarily by homologous recombination (HR). Since almost all HR events are significantly reduced in the rad52 mutant cells, the Rad52 protein is believed to be a key component of HR in S. cerevisiae. Similarly to the S. cerevisiae Rad52 protein, RecA is the main HR protein in Escherichia coli. To address the question of whether the E. coli RecA protein can rescue HR defective phenotype of the rad52 mutants of S. cerevisiae, the recA gene was introduced into the wild-type and rad52 mutant cells. Cell survival and DSBs induction and repair were studied in the RecA-expressing wild-type and rad52 mutant cells after exposure to ionizing radiation (IR) and methyl methanesulphonate (MMS). Here, we show that expression of the E. coli RecA protein partially complemented sensitivity and fully complemented DSB repair defect of the rad52 mutant cells after exposure to IR and MMS. We suggest that in the absence of Rad52, when all endogenous HR mechanisms are knocked out in S. cerevisiae, the heterologous E. coli RecA protein itself presumably takes over the broken DNA.     

Novel 1,3,5-Triazinyl Aminobenzenesulfonamides Incorporating Aminoalcohol,Aminochalcone and Aminostilbene Structural Motifs as Potent Anti-VRE Agents,and Carbonic Anhydrases I,II, VII,IX, and XII Inhibitors

A series of 1,3,5-triazinyl aminobenzenesulfonamides substituted by aminoalcohol, aminostilbene, and aminochalcone structural motifs was synthesized as potential human carbonic anhydrase (hCA) inhibitors. The compounds were evaluated on their inhibition of tumor-associated hCA IX and hCA XII, hCA VII isoenzyme present in the brain, and physiologically important hCA I and hCA II. While the test compounds had only a negligible effect on physiologically important isoenzymes, many of the studied compounds significantly affected the hCA IX isoenzyme. Several compounds showed activity against hCA XII; (E)-4-{2-[(4-[(2,3-dihydroxypropyl)amino]-6-[(4-styrylphenyl)amino]-1,3,5-triazin-2-yl)amino]ethyl}benzenesulfonamide (31) and (E)-4-{2-[(4-[(4-hydroxyphenyl)amino]-6-[(4-styrylphenyl)amino]-1,3,5-triazin-2-yl)amino]ethyl}benzenesulfonamide (32) were the most effective inhibitors with K_Is = 4.4 and 5.9 nM, respectively. In addition, the compounds were tested against vancomycin-resistant Enterococcus faecalis (VRE) isolates. (E)-4-[2-({4-[(4-cinnamoylphenyl)amino]-6-[(4-hydroxyphenyl)amino]-1,3,5-triazin-2-yl}amino)ethyl]benzenesulfonamide (21) (MIC = 26.33 µM) and derivative 32 (MIC range 13.80–55.20 µM) demonstrated the highest activity against all tested strains. The most active compounds were evaluated for their cytotoxicity against the Human Colorectal Tumor Cell Line (HCT116 p53 +/+). Only 4,4’-[(6-chloro-1,3,5-triazin-2,4-diyl)bis(iminomethylene)]dibenzenesulfonamide (7) and compound 32 demonstrated an IC₅₀ of ca. 6.5 μM; otherwise, the other selected derivatives did not show toxicity at concentrations up to 50 µM. The molecular modeling and docking of active compounds into various hCA isoenzymes, including bacterial carbonic anhydrase, specifically α-CA present in VRE, was performed to try to outline a possible mechanism of selective anti-VRE activity.     

Synthesis and magnetorheological characteristics of ribbon‐like,polypyrrole‐coated carbonyl iron suspensions under oscillatory shear

One of the crucial problems of classical magnetorheological (MR) fluids is their high rate of sedimentation. This disadvantage may be substantially eliminated using core‐shell particles. The aim of this study is to prepare spherical carbonyl iron (CI) particles coated with conducing polymer polypyrrole (PPy) with ribbon‐like morphology. Scanning electron microscopy proved the formation of the ribbon‐like layer onto CI particles while Fourier transform infrared spectroscopy confirmed the chemical structure of PPy. The magnetic properties observed via vibrating sample magnetometer showed decreased magnetization saturation of core‐shell‐structured particles due to the existence of non‐magnetic surface layer. MR measurements performed under oscillatory shear flow as a function of the applied magnetic flux density, temperature, and particle concentration showed that core‐shell particle‐based MR suspension exhibits sufficient MR performance for practical applications. Moreover, the suspension stability is promoted significantly when core‐shell particles are used as a dispersed phase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Assessment of gel formation in colloidal dispersions during mixing in turbulent jets

Onset of gel formation upon mixing between colloidal dispersions and coagulant solutions in turbulent jets was studied using a combination of computational fluid dynamics (CFD) and population balance equation (PBE). To describe the interaction between turbulence fluctuations and particle aggregation, a micromixing model based on presumed probability density function was implemented inside the CFD code. Furthermore, effect of the solid phase on the fluid flow was modeled through an effective viscosity of the mixture evaluated from PBE. The results are presented in the parameter space of the primary particle diameter and the solid volume fraction where strong interplay between mixing and aggregation mechanisms controls the gelation phenomena and consequently also the fluid dynamics. Simulation results are in good agreement with observations from gelation experiments of concentrated nanoparticle suspensions injected into coagulant solutions. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4567–4581, 2013     

DRYING RESEARCH AND DEVELOPMENT IN CZECHOSLOVAKIA

This paper provides general information on drying R 6D activities in Czechoslovakia. This survey report lists the main topics in drying according to individual industrial sectors in which drying plays an important role. Drying R 6D carried out in Czechoslovak Universities is also cited. The paper includes an extensive list of references, mainly proceedings of national drying conferences, symposia, and meetings     

Color-tunable up-conversion emission in Y2O3:Yb3+, Er3+ nanoparticles prepared by polymer complex solution method

Abstract

Powders of Y₂O₃ co-doped with Yb³⁺ and Er³⁺ composed of well-crystallized nanoparticles (30 to 50 nm in diameter) with no adsorbed ligand species on their surface are prepared by polymer complex solution method. These powders exhibit up-conversion emission upon 978-nm excitation with a color that can be tuned from green to red by changing the Yb³⁺/Er³⁺ concentration ratio. The mechanism underlying up-conversion color changes is presented along with material structural and optical properties.

PACS

42.70.-a, 78.55.Hx, 78.60.-b