Dielectric relaxation of water absorbed in porous glass

The dielectric spectroscopy method was applied to the investigation of water absorbed on the inner surface of porous glass. The measurements were done using broad band dielectric spectrometry (BEDS) over a wide range of frequency (20 Hz to 1 MHz) and temperature (-100 °C to +300 °C). The dielectric response was found to be very sensitive to the geometrical micro- and mesostructural features of the porous matrix and the structure and mobility of the water filling the pores. The hindered dynamics of water molecules located within the pores and affected by the surfaces reflect the geometrical structure of the porous matrix. The analysis of the dielectric parameters as a function of the temperature enabled us to characterize the physical parameters of the dielectric spectra over an extended frequency range. © 2001 American Chemical Society

Dielectric relaxation of water in clay minerals

The study of confined water dynamics in clay minerals is a very important topic in aluminosilicate-surface chemistry. Aluminosilicates are among the most technologically versatile materials in industry today. Dielectric spectroscopy is a very useful method for investigating the structure and dynamics of water adsorbed on solid matrix surfaces and water in the vicinity of ions in solutions. Use of this method for the study of clay minerals has been underutilized to date, however. The main goal of the present research was to understand the relaxation mechanisms of water molecules interacting with different hydration centers in clay minerals, with a view to eventually control this interaction. Two types of natural layered aluminosilicates (clay minerals) montmorillonite with exchangeable K+, Co2+, and Ni2+ cations and kaolinite with exchangeable K+ and Ba2+ cations were examined by means of dielectric spectroscopy over wide ranges of temperature (from -121°C to +300°C) and frequency (1 Hz-1 MHz). An analysis of the experimental data is provided in terms of four distributed relaxation processes. The low-temperature relaxation was observed only in montmorillonites and could be subdivided into two processes, each related to a specific hydration center. The cooperative behavior of water at the interface was observed in the intermediate temperature region, together with a proton percolation. The dielectric properties of ice-like and confined water structures in the layered clay minerals were compared with the dielectric response observed in porous glasses. The spatial fractal dimensions of the porous aluminosilicates were calculated by two separate methods - from an analysis of the fractality found in photomicrographs and from the dielectric response

Effect of short PSG peptide fragments on the cytokine profile in Wistar rats during allogeneic transplantation <i>in vivo</i>

Pregnancy-specific beta-1-glycoprotein (PSG) is a protein with pleiotropic biological effects, particularly immunoregulatory and immunosuppressive potential. The use of recombinant PSG may exert therapeutic effects in experimental animals with induced autoimmune diseases. Recently, a search for the biological effects of short linear motifs (SLiMs) has become a new strategy for designing the pharmacological compounds. Tetrapeptide regions have been identified in the primary structure of several PSGs: YQCE, YECE and YACS, these SLiMs exhibit immunomodulatory activity. The aim of our study was to evaluate the prospectives for usage of PSG peptide fragments as pharmacological agents to modulate transplant immunity. We used an original model of host-versus-graft response in male Wistar rats transplanted with bone marrow, without prior conditioning treatment of recipients. We used a cocktail of the PSG peptide fragments administered to Wistar rats in the course of allogeneic bone marrow transplantation (BM) in dynamic manner, evaluating the cytokine profile as an integral index of immune response. Cytokine levels were determined by multiplex method using Bio-Plex ProTM Rat 23-Plex kit. Statistical processing of the data was performed by means of two-way analysis of variance and Tukey’s post hoc test for multiple comparisons. We have found that the levels of pro-inflammatory cytokines (IFNγ, IL-1α, IL-1β, IL-18), as well as the contents of G-CSF, GM-CSF and IL-7 were increased in the animals injected with BM only. In the group of animals injected with BM + PSG peptides, an increase in IFNγ, IL-6, TNFα was observed, which decreased by the end of the experiment. Increased levels of antiinflammatory cytokines IL-4 and IL-13 were detected in blood serum of the animals on day +14. Moreover, administration of PSG peptides also led to increase in IL-2, M-CSF, MCP-1, and RANTES levels on day 14 from the beginning of the experiment, and to a gradual decrease in their levels till the end of the experiment. Meanwhile, control group showed a marked tendency for increase of these and other cytokines. Thus, it was shown that the use of PSG peptides upon development of immune response to BM allograft may promote a return to normal levels for the most cytokines studied, thus presuming the immunopharmacological potential of these peptides. The obtained data can be used to develop a pharmacological preparation of the studied peptides to correct the imbalance of immune system

Dielectric relaxation of water absorbed in porous glass

The dielectric spectroscopy method was applied to the investigation of water absorbed on the inner surface of porous glass. The measurements were done using broad band dielectric spectrometry (BEDS) over a wide range of frequency (20 Hz to 1 MHz) and temperature (-100 °C to +300 °C). The dielectric response was found to be very sensitive to the geometrical micro- and mesostructural features of the porous matrix and the structure and mobility of the water filling the pores. The hindered dynamics of water molecules located within the pores and affected by the surfaces reflect the geometrical structure of the porous matrix. The analysis of the dielectric parameters as a function of the temperature enabled us to characterize the physical parameters of the dielectric spectra over an extended frequency range. © 2001 American Chemical Society

Dielectric relaxation of water absorbed in porous glass

The dielectric spectroscopy method was applied to the investigation of water absorbed on the inner surface of porous glass. The measurements were done using broad band dielectric spectrometry (BEDS) over a wide range of frequency (20 Hz to 1 MHz) and temperature (-100 °C to +300 °C). The dielectric response was found to be very sensitive to the geometrical micro- and mesostructural features of the porous matrix and the structure and mobility of the water filling the pores. The hindered dynamics of water molecules located within the pores and affected by the surfaces reflect the geometrical structure of the porous matrix. The analysis of the dielectric parameters as a function of the temperature enabled us to characterize the physical parameters of the dielectric spectra over an extended frequency range. © 2001 American Chemical Society

Dielectric relaxation of water absorbed in porous glass

The dielectric spectroscopy method was applied to the investigation of water absorbed on the inner surface of porous glass. The measurements were done using broad band dielectric spectrometry (BEDS) over a wide range of frequency (20 Hz to 1 MHz) and temperature (-100 °C to +300 °C). The dielectric response was found to be very sensitive to the geometrical micro- and mesostructural features of the porous matrix and the structure and mobility of the water filling the pores. The hindered dynamics of water molecules located within the pores and affected by the surfaces reflect the geometrical structure of the porous matrix. The analysis of the dielectric parameters as a function of the temperature enabled us to characterize the physical parameters of the dielectric spectra over an extended frequency range. © 2001 American Chemical Society

Dielectric relaxation of water in clay minerals

The study of confined water dynamics in clay minerals is a very important topic in aluminosilicate-surface chemistry. Aluminosilicates are among the most technologically versatile materials in industry today. Dielectric spectroscopy is a very useful method for investigating the structure and dynamics of water adsorbed on solid matrix surfaces and water in the vicinity of ions in solutions. Use of this method for the study of clay minerals has been underutilized to date, however. The main goal of the present research was to understand the relaxation mechanisms of water molecules interacting with different hydration centers in clay minerals, with a view to eventually control this interaction. Two types of natural layered aluminosilicates (clay minerals) montmorillonite with exchangeable K+, Co2+, and Ni2+ cations and kaolinite with exchangeable K+ and Ba2+ cations were examined by means of dielectric spectroscopy over wide ranges of temperature (from -121°C to +300°C) and frequency (1 Hz-1 MHz). An analysis of the experimental data is provided in terms of four distributed relaxation processes. The low-temperature relaxation was observed only in montmorillonites and could be subdivided into two processes, each related to a specific hydration center. The cooperative behavior of water at the interface was observed in the intermediate temperature region, together with a proton percolation. The dielectric properties of ice-like and confined water structures in the layered clay minerals were compared with the dielectric response observed in porous glasses. The spatial fractal dimensions of the porous aluminosilicates were calculated by two separate methods - from an analysis of the fractality found in photomicrographs and from the dielectric response

Dielectric relaxation of water in clay minerals

The study of confined water dynamics in clay minerals is a very important topic in aluminosilicate-surface chemistry. Aluminosilicates are among the most technologically versatile materials in industry today. Dielectric spectroscopy is a very useful method for investigating the structure and dynamics of water adsorbed on solid matrix surfaces and water in the vicinity of ions in solutions. Use of this method for the study of clay minerals has been underutilized to date, however. The main goal of the present research was to understand the relaxation mechanisms of water molecules interacting with different hydration centers in clay minerals, with a view to eventually control this interaction. Two types of natural layered aluminosilicates (clay minerals) montmorillonite with exchangeable K+, Co2+, and Ni2+ cations and kaolinite with exchangeable K+ and Ba2+ cations were examined by means of dielectric spectroscopy over wide ranges of temperature (from -121°C to +300°C) and frequency (1 Hz-1 MHz). An analysis of the experimental data is provided in terms of four distributed relaxation processes. The low-temperature relaxation was observed only in montmorillonites and could be subdivided into two processes, each related to a specific hydration center. The cooperative behavior of water at the interface was observed in the intermediate temperature region, together with a proton percolation. The dielectric properties of ice-like and confined water structures in the layered clay minerals were compared with the dielectric response observed in porous glasses. The spatial fractal dimensions of the porous aluminosilicates were calculated by two separate methods - from an analysis of the fractality found in photomicrographs and from the dielectric response