Influence of Tea Brewing Parameters on the Antioxidant Potential of Infusions and Extracts Depending on the Degree of Processing of the Leaves of Camellia sinensis

The polyphenol content of tea depends on the growing region, harvest date, the production process used, and the brewing parameters. In this study, research was undertaken that included an analysis of the influence of the brewing process parameters on the content of total polyphenols (Folin-Ciocalteu), epigallocatechin gallate (HPLC), and antioxidant activity (against DPPH radicals) of fresh tea shrub leaves grown from Taiwan and of teas obtained from them (oolong, green in bags, and green loose from the spring and autumn harvest). The antioxidant potential was determined in the methanol and aqueous extracts, as well as in infusions that were obtained by using water at 65 or 100 °C and infusing the tea for 5 or 10 min. The highest content of total polyphenols and epigallocatechin gallate was found in green tea extracts from the spring harvest. However, in the case of infusions, the highest content of these compounds was found in green tea in bags. Steaming at 100 °C for 10 min, turned out to be the most favourable condition for the extraction. Oolong tea, brewed at 100 °C for 5 min was characterised by the highest antioxidant activity against stable DPPH radicals.     

Design and Optimization of a Biosensor Surface Functionalization to Effectively Capture Urinary Extracellular Vesicles

For this study, we tested and optimized silicon surface functionalization procedures for capturing urinary extracellular vesicles (uEVs). The influence of the silane type (APTES or GOPS) and protein concentration on the efficiency of uEVs binding was investigated. Human lactadherin protein (LACT) was used to capture uEVs. We applied surface characterization techniques, including ellipsometry, atomic force microscopy, and time-of-flight secondary ion mass spectrometry, to observe changes in the biosensor surface after each functionalization step. uEVs were purified by a low-vacuum filtration method and concentrated by ultracentrifugation. The physical parameters of uEVs after the isolation procedure, such as morphology and size distribution, were determined using transmission electron microscopy and tunable resistive pulse sensing methods. We observed a gradual growth of the molecular layer after subsequent stages of modification of the silicon surface. The ToF-SIMS results showed no changes in the mean intensities for the characteristic peaks of amino acids and lipids in positive and negative polarization, in terms of the surface-modifying silane (APTES or GOPS) used. The most optimal concentration of LACT for the tested system was 25 µg/mL.     

Physical properties of 8OS5 thioester studied by complementary methods

ABSTRACT

Properties of 4-n-pentylphenyl-4’-n-octyloxythiobenzoate (8OS5), belonging to the nOS5 homologous series, have been studied by complementary methods. The phase sequence, the phase transition temperatures, the thickness of molecular layers, the average distance between long axes of molecules and the correlation length were determined during cooling and heating. For the first time, simultaneous X-ray diffraction and differential scanning calorimetry measurements have been used to study mesomorphic properties. The results are compared with the ones obtained in standard measurements by means of differential scanning calorimetry, X-ray diffraction and polarizing optical microscopy. Meaning of experimental procedures applied in investigations of monotropic mesophases below a melting point is discussed.     

Coal characterization by on-line pyrolysis-field ionization mass spectrometry

Summary Pyrolysis-field ionization mass spectrometry (Py-FIMS) was used for the first time to directly characterize Chinese coals and their extracts. The summed mass spectra (about 30 magnetic scans) of four coal samples and the dimethylformamide extracts of two very different coals were registered between 50° and 750°C using linear heating in high vacuum (10^–3 Pa) and approximately 6 min temperature rise time. Utilizing temperature-programmed pyrolysis and FI as soft ionization mode, the spectra displayed almost exclusively molecular ions of the evolved products. The thermograms, i.e. the intensities of the total ion current and selected ions were plotted versus the scan number, heating time and temperature. In general, two maxima in these thermograms were observed, which were different for the coals and reflected their carbon/hydrogen content. Comparing the mass spectra of the low temperature part (first maximum) with summed spectra of the extracts shows an interesting similarity. In contrast, the high temperature part (second maximum) indicates the products of thermo-degradation. The applied method is a fast and convenient tool for the characterization of evolved volatiles and thermal degradation products of coals and coal extracts.

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Kennzeichnung von Kohlen mit direkter Pyrolyse und Feldionisations-Massenspektrometrie

     

Microscopic mechanism of adsorption in cylindrical nanopores with heterogenous wall structure

We study the microscopic mechanism of adsorption in nanometric cylindrical pores with strongly heterogeneous walls using grand canonical Monte Carlo simulations. The pore surface structure is modeled by a new lattice-site approach. Each site is characterized by two amplitudes--structural and energetic--that locally modify the structural and energetic properties of the surface. The amplitudes are randomly distributed over the pore wall. We have shown that different structural and energetic distribution functions lead to different mechanism of adsorption. The energetic site distribution plays the most crucial role in the submonolayer region. The structural site distribution modifies the multilayer adsorption. A method to analyze the stability of the adsorbed system using static susceptibility is proposed. Potential applications in multiscale modeling are discussed.     

Dielectric properties of a protein-water system in selected animal tissues

Dielectric spectroscopy has been applied to study aspects of the organization of water in selected animal tissues (tendon, bone and horn). The measurements of the relative permittivity epsilon' and the dielectric loss epsilon' were carried over the frequency range of 10-100 kHz and at temperatures from 22 to 240 degrees C. The water content was 10% for bone and horn, and 22% for tendon by mass at room temperature at a relative humidity of 70%. The temperature dependencies of epsilon' and epsilon' reveal distinctively the temperature ranges corresponding to the release of water in temperatures up to about 200 degrees C for all tissues and the melting of the crystalline structure only for tendon and horn, above this temperature. The frequency dependencies of epsilon' and epsilon' show a remarkable dispersion in the low-frequency at selected temperatures up to 200 degrees C for all tissues due to the release of the loosely and strongly bound water. The results were discussed in terms of the interfacial (Maxwell-Wagner) polarization and polarization mechanism involving hopping charge carriers interacting with the bound water molecules. The information on the effect of temperature, water content and frequency of the electromagnetic field on the dielectric behaviour of the tissues studied is of importance in the design and construction of medical diagnostic or therapeutic instruments based on the use of electric signals.     

Amino Acid Assisted Incorporation of Dye Molecules within Calcite Crystals

Biomineralisation processes invariably occur in the presence of multiple organic additives, which act in combination to give exceptional control over structures and properties. However, few synthetic studies have investigated the cooperative effects of soluble additives. This work addresses this challenge and focuses on the combined effects of amino acids and coloured dye molecules. The experiments demonstrate that strongly coloured calcite crystals only form in the presence of Brilliant Blue R (BBR) and four of the seventeen soluble amino acids, as compared with almost colourless crystals using the dye alone. The active amino acids are identified as those which themselves effectively occlude in calcite, suggesting a mechanism where they can act as chaperones for individual molecules or even aggregates of dyes molecules. These results provide new insight into crystal–additive interactions and suggest a novel strategy for generating materials with target properties.     

Bias field influence on dielectric spectra of B phases of bent-core thioesters

Smectic B₂ phase of bent-core 1,3-phenylene bis{4-[(4-dodecyloxybenzoyl)sulfanyl]benzoate} (12OSOR) and a mixture 12R9AF have been studied using dielectric and electrooptic methods. 12R9AF is a mixture of bent-core 12OSOR and calamitic chiral MHPSBO9 materials. The B₂ phase of 12R9AF mixture is shifted to lower temperatures by about 10 °C in comparison with pure 12OSOR. Spontaneous polarization of the mixture is comparable with spontaneous polarization of pure compound. Dielectric measurements were done using dielectric spectrometer based on Agilent 4294A impedance analyzer. Dielectric spectra measured with bias field for B₂ phase of 12OSOR and 12R9AF show two well separated relaxation processes.     

Electrooptic study of antiferroelectric mixtures for display application

The aim of this paper is to study the influence of electric field on alignment of para-, ferro- and antiferroelectric phases in the vicinity of SmA^* — SmC^* or SmC^* — SmC _A ^* phase transitions as to obtain mono-domain cells. Four mixtures studied (W-193B, W-193B-1, W-201, W-204D) show the SmC _A ^* phase in a wide room temperature range. Measurements of the spontaneous polarization versus temperature by using reversal current method give an answer to the question, what kind of the transitions take place between para-, ferro- or antiferroelectric phases using the Landau mean field theory. Optimal electrooptic parameters for different compositions of the mixtures such as tilt angle, spontaneous polarization and saturation voltage have been measured to compare parameters of the mixtures studied.     

Red Blood Cells Polarize Green Laser Light Revealing Hemoglobin′s Enhanced Non‐Fundamental Raman Modes

In general, the first overtone modes produce weak bands that appear at approximately twice the wavenumber value of the fundamental transitions in vibrational spectra. Here, we report the existence of a series of enhanced non‐fundamental bands in resonance Raman (RR) spectra recorded for hemoglobin (Hb) inside the highly concentrated heme environment of the red blood cell (RBC) by exciting with a 514.5 nm laser line. Such bands are most intense when detecting parallel‐polarized light. The enhancement is explained through excitonic theory invoking a type C scattering mechanism and bands have been assigned to overtone and combination bands based on symmetry arguments and polarization measurements. By using malaria diagnosis as an example, we demonstrate that combining the non‐fundamental and fundamental regions of the RR spectrum improves the sensitivity and diagnostic capability of the technique. The discovery will have considerable implications for the ongoing development of Raman spectroscopy for blood disease diagnoses and monitoring heme perturbation in response to environmental stimuli.