Indirect,non-competitive amperometric immunoassay for accurate quantification of calpastatin,a meat tenderness marker,in bovine muscle

A method is described for quantification of the beef tenderness marker, calpastatin, in meat samples by amperometric detection. Using a novel bovine recombinant partial calpastatin protein as standard antigen a low detection limit of 0.2 ng/mL was achieved. The influence of the complex matrix was minimised by heat pretreatment and dilution of the samples prior to detection of calpastatin. The relative error between the direct sample measurement and standard addition methods was 5.89%, confirming the accuracy of the developed amperometric immunoassay.     

Stresses Generated During Convective and Microwave Drying

An outline of the mechanistic model of convective and microwave drying of saturated capillary-porous materials is presented. The model was derived in the framework of irreversible thermodynamics. Particular attention is devoted to construction of the term describing the power of microwave radiation absorbed per unit volume, which is converted into internal heat source. The qualitative difference in distribution of temperature, moisture content, and the drying-induced stresses in materials under convective and microwave drying is illustrated in the examples of cylindrical kaolin samples. The diagrams of acoustic emission are taken off on-line from these samples in order to illustrate the development of material destruction caused by the stresses induced during both convective and microwave drying.     

Cerebral Pericytes and Endothelial Cells Communicate through Inflammasome-Dependent Signals

By upregulation of cell adhesion molecules and secretion of proinflammatory cytokines, cells of the neurovascular unit, including pericytes and endothelial cells, actively participate in neuroinflammatory reactions. As previously shown, both cell types can activate inflammasomes, cerebral endothelial cells (CECs) through the canonical pathway, while pericytes only through the noncanonical pathway. Using complex in vitro models, we demonstrate here that the noncanonical inflammasome pathway can be induced in CECs as well, leading to a further increase in the secretion of active interleukin-1β over that observed in response to activation of the canonical pathway. In parallel, a more pronounced disruption of tight junctions takes place. We also show that CECs respond to inflammatory stimuli coming from both the apical/blood and the basolateral/brain directions. As a result, CECs can detect factors secreted by pericytes in which the noncanonical inflammasome pathway is activated and respond with inflammatory activation and impairment of the barrier properties. In addition, upon sensing inflammatory signals, CECs release inflammatory factors toward both the blood and the brain sides. Consequently, CECs activate pericytes by upregulating their expression of NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3), an inflammasome-forming pattern recognition receptor. In conclusion, cerebral pericytes and endothelial cells mutually activate each other in inflammation.     

Silicon compounds as additives improving coating performance: fixation of silicon compounds with cellulose

In this study the reactivity of cellulose with new solvent born preparations containing organosilanes, alkyd resin and natural oil was analysed. Structural analysis of cellulose after reaction with organosilanes and after extraction was performed using Fourier-transform infrared spectroscopy (FTIR). In IR spectra the analyzed bands included 1250 cm^?1 responsible for vibrations of the SiC group and 800 cm^?1 responsible for vibrations of SiC and/or SiO groups. These bands are characteristic of silicon bonds with atoms of carbon and oxygen originating from the methoxy groups found in organosilanes. The presence of these bands in the spectra proves the occurrence of a reaction between cellulose and organosilanes. The concentration of silicon was determined by AAS in cellulose after reaction with preparations and after extraction.     

Step-scan alternating DSC study of melting and crystallisation in poly(ethylene oxide)

Step-scan alternating differential scanning calorimetry (SSA-DSC) method was applied to investigate the phase behaviour of well-characterised poly(ethylene oxide) (PEO). Influence of the three main measurement's parameters of SSA-DSC method: length of the isothermal segment (t_iso/s), temperature jump between two subsequent isothermal segments (step/deg) and linear heating rate in dynamic segments (b/K/min), on the shape of reversing and non-reversing components during the melting and crystallisation of PEO, has been evaluated. It was found that the reversing component during melting of PEO is increasing with an increase of the isothermal segment length. This effect is due to the existence of defected polymer crystal structures that form metastable regions between crystal phase and already melted polymer. Reversible recrystallisation in the presence of still existing polymer crystals is facilitated by longer isothermal segments. By increasing the step, the equilibrium of reversible processes is shifted towards products and activation of rate-controlled processes takes place; molecular nucleation is hampered and partial melting and/or recrystallisation proceed slower—this effect can be observed as a decrease of reversing signal with increasing step.     

Proton Binding Is Part of Protein Relaxation of Flash-Excited Reaction Center from Photosynthetic Bacteria Rhodobacter sphaeroides

In the first part of this work, a brief review is presented of the recent knowledge of charge stabilization processes in flash-excited reaction center protein from photosynthetic bacteria Rhodobacter sphaeroides. The adaptation of the protein to charge separation is comprised of different manifestations of protein relaxation including proton binding at the late phase. In the second part, a unique method, comparative measurement of prompt and millisecond-delayed fluorescence of the bacteriochlorophyll dimer of the reaction center protein is used to determine the free energy levels of the charge-separated states with respect to that of the excited singlet state of the dimer: −910 ± 20 meV and −970 ± 20 meV were measured at pH 8.0 for reaction centers in the absence and presence of secondary quinone, respectively. The pH-dependence of the energetics of charge stabilization due to light-induced proton binding is described in reaction centers with and without secondary quinone activity. The range of free-energy change between pH 11 and pH 5 was −65 meV with a single (alkaline) inflection point (no active secondary quinone) and −175 meV with an additional (acidic) inflection point (active secondary quinone). The conclusions from fluorescence data agreed well with pH-dependence of integrated proton uptake (a model-independent method) and with calculations based on interaction of quinones with four key amino acid residues. The enthalpy and entropy parts of the free-energy changes were determined from van't Hoff analysis of the delayed fluorescence and compared with data of other methods. It is concluded that the charge stabilization including proton binding is a highly enthalpy-driven process.     

In situ ESR response to temperature evolution of styrene/dibenzoyl peroxide/Di‐TEMPO biradical system

The initial stage of the di‐TEMPO (N,N′‐bis(4‐(2,2,6,6‐tetramethylpiperidin‐1‐yloxyl))diaminobutane) controlled radical polymerization of styrene was investigated by electron spin resonance (ESR) method in a temperature range of 300–410 K. Processes corresponding to three subsequent temperature subranges 300–360, 360–375, and 375–410 K have been discussed. The decrease of concentration of the di‐TEMPO biradicals is faster than for the TEMPO monoradicals in the range 370–390 K. The reduced mobility of capping groups is postulated to be responsible for the differences between TEMPO monoradical and di‐TEMPO biradical mediators. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A Theoretical Study of the Half-Sandwich Silicon(II) Cation [(Me<Subscript>5</Subscript>C<Subscript>5</Subscript>)Si]<Superscript>+</Superscript> and of the Cationic Complex [(Me<Subscript>5</Subscript>C<Subscript>5</Subscript>)Si (DME)]<Superscript>+</Superscript>

Ab-initio calculations have been performed for the half-sandwich cation [(Me₅C₅)Si]⁺ and its DME complex [(Me₅C₅)Si(DME)]⁺. For these cations, the ground state energies, the complexation energy, the frontier orbitals, the vertical singlet-triplet excitation energies, and the natural atomic charges have been calculated. In both cations, the “lone-pair” at silicon does not represent the HOMO. The nature of the weak dative O → Si bond can best be described in terms of electrostatic and attractive dispersion interactions. The DME coordination destabilizes the cluster orbitals and slightly enhances the positive charge at silicon.