61 research outputs found
Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus -- the "D-shuttle" project --
Twelve high schools in Japan (of which six are in Fukushima Prefecture), four
in France, eight in Poland and two in Belarus cooperated in the measurement and
comparison of individual external doses in 2014. In total 216 high-school
students and teachers participated in the study. Each participant wore an
electronic personal dosimeter "D-shuttle" for two weeks, and kept a journal of
his/her whereabouts and activities. The distributions of annual external doses
estimated for each region overlap with each other, demonstrating that the
personal external individual doses in locations where residence is currently
allowed in Fukushima Prefecture and in Belarus are well within the range of
estimated annual doses due to the background radiation level of other
regions/countries
Mitochondrial Variability as a Source of Extrinsic Cellular Noise
We present a study investigating the role of mitochondrial variability in
generating noise in eukaryotic cells. Noise in cellular physiology plays an
important role in many fundamental cellular processes, including transcription,
translation, stem cell differentiation and response to medication, but the
specific random influences that affect these processes have yet to be clearly
elucidated. Here we present a mechanism by which variability in mitochondrial
volume and functionality, along with cell cycle dynamics, is linked to
variability in transcription rate and hence has a profound effect on downstream
cellular processes. Our model mechanism is supported by an appreciable volume
of recent experimental evidence, and we present the results of several new
experiments with which our model is also consistent. We find that noise due to
mitochondrial variability can sometimes dominate over other extrinsic noise
sources (such as cell cycle asynchronicity) and can significantly affect
large-scale observable properties such as cell cycle length and gene expression
levels. We also explore two recent regulatory network-based models for stem
cell differentiation, and find that extrinsic noise in transcription rate
causes appreciable variability in the behaviour of these model systems. These
results suggest that mitochondrial and transcriptional variability may be an
important mechanism influencing a large variety of cellular processes and
properties
Degradation, Bioactivity, and Osteogenic Potential of Composites Made of PLGA and Two Different SolâGel Bioactive Glasses
We have developed poly(l-lactide-co-glycolide) (PLGA) based composites using solâgel derived bioactive glasses (S-BG), previously described by our group, as composite components. Two different composite types were manufactured that contained either S2âhigh content silica S-BG, or A2âhigh content lime S-BG. The composites were evaluated in the form of sheets and 3D scaffolds. Sheets containing 12, 21, and 33Â vol.% of each bioactive glass were characterized for mechanical properties, wettability, hydrolytic degradation, and surface bioactivity. Sheets containing A2 S-BG rapidly formed a hydroxyapatite surface layer after incubation in simulated body fluid. The incorporation of either S-BG increased the tensile strength and Youngâs modulus of the composites and tailored their degradation rates compared to starting compounds. Sheets and 3D scaffolds were evaluated for their ability to support growth of human bone marrow cells (BMC) and MG-63 cells, respectively. Cells were grown in non-differentiating, osteogenic or osteoclast-inducing conditions. Osteogenesis was induced with either recombinant human BMP-2 or dexamethasone, and osteoclast formation with M-CSF. BMC viability was lower at higher S-BG content, though specific ALP/cell was significantly higher on PLGA/A2-33 composites. Composites containing S2 S-BG enhanced calcification of extracellular matrix by BMC, whereas incorporation of A2 S-BG in the composites promoted osteoclast formation from BMC. MG-63 osteoblast-like cells seeded in porous scaffolds containing S2 maintained viability and secreted collagen and calcium throughout the scaffolds. Overall, the presented data show functional versatility of the composites studied and indicate their potential to design a wide variety of implant materials differing in physico-chemical properties and biological applications. We propose these solâgel derived bioactive glassâPLGA composites may prove excellent potential orthopedic and dental biomaterials supporting bone formation and remodeling
The importance of partial chemical equilibrium for the formation of groundwater chemistry in silicate systems of the weathered zone
Partial chemical equilibrium plays an important role in geochemical systems. In the short turn-over time zone of hydrogeological systems, the conditions for the full chemical equilibrium amongst groundwaters, mineral phases and gases are rarely fulfilled. In these systems, partial chemical equilibrium is often responsible for controlling activity of solutes. Examples of partial chemical equilibrium with secondary phases in silicate systems of the weathered zone are given, and the role of metastable and stable secondary silicate solids is discussed
Geochemical modelling-a tool for understanding geochemistry of groundwater systems. Case studies, and present-day state in Poland
Potential of geochemical modelling for groundwater systems, with the most important up-to-date literature was concisely described. Case studies considering different methods of geochemical modelling used for understanding of groundwater systems geochemistry are presented. Most of case studies concern modelling of groundwater in short turn-over time zone in the Sudetes Mts. (SW Poland). Present-day geochemical modelling state-of-art in Poland was discussed and evaluated
The role of partial chemical equilibrium for silicon activity controlling in curative mineral waters, the Sudetes, Poland
SkĹad chemiczny sudeckich wĂłd leczniczych zostaĹ poddany interpretacji z punktu widzenia kontroli rozpuszczalnoĹci krzemu. W termalnych wodach leczniczych LÄ
dka-Zdroju i Cieplic ĹlÄ
skich-Zdroju istniejÄ
warunki sprzyjajÄ
ce trwaĹoĹci koloidu glinokrzemianowego HASB. AktywnoĹÄ krzemu w zarĂłwno chĹodnych, jak i termalnych wodach leczniczych moĹźe byÄ kontrolowana przez czÄĹciowe rĂłwnowagi chemiczne reakcji inkongruentnego rozpuszczania faz glinokrzemianowych z utworzeniem Al(OH)3.Chemical composition of curative mineral waters from the Sudetic spas was interpreted in terms of silicon solubility control. In thermal waters from LÄ
dek-ZdrĂłj and Cieplice ĹlÄ
skie-ZdrĂłj, conditions for stability of hydroxyaluminosilicate HASB are maintained. In both cold and thermal waters, silicon might be controlled by partial chemica
Research of redox potential on the example of curativewaters in the Sudetes Mts., Poland
In Poland, the redox potential (EH) is seldomly measured in groundwater. Since the year 2006 determination of redox potential is required for documenting properties of curative mineral waters. Investigations of redox conditions in groundwater need both proper measurement and interpretation. In the paper, crucial questions of: 1) redox equilibrium in groundwater, 2) field measurement, 3) correction methods, and 4) EH interpretation are presented. Some aspects of applying the redox potential for interpreting groundwater chemistry and using geochemical modelling are illustrated by hydrochemical data of curative waters from spas in the Sudetes Mts., SW Poland. Main reasons of the common redox non-equilibrium found in groundwater are co-existence of numerous aqueous redox pairs and usually non-equilibrium in particular redox pairs. Redox determinations have to be done in the field, and require extreme cleanness and precision, e.g., measuring without contact with the atmospheric air. Field measurements must be corrected to the standard hydrogen electrode, considering: type of reference electrode, concentration of electrode filling solution, type of standard redox solution, and water temperature. The redox potential has been measured in water at first from all the Sudetic spas, totally in 33 water intakes. In curative waters from the Sudetes corrected EH ranges between â159 mV and +343 mV. Usually, thermal waters show lower EH values than cold, CO2-rich waters. The lowest redox potential was found in the hottest thermal waters, i.e., in water from ZdzisĹaw intake (in LÄ
dek ZdrĂłj) and C-2 intake (in Cieplice ĹlÄ
skie ZdrĂłj). Generally, the higher the pH, the lower the EH in groundwater. Methods of geochemical modelling, which are often and often applied in groundwater research, also require the EH determination. Information about EH are used in the calculation of speciation models of water, and affect the results of whole geochemical modelling as well as evaluations of the saturation state. The speciation-solubility modelling for the Sudetic curative waters, presented in the paper, shows that the proper correction of field EH measurement determines the quality of calculations. Improperly corrected EH values might lead to species activity errors, even up to several order of magnitudes, and erroneous interpretation of the mineral phases stability in the hydrogeochemical system
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