111 research outputs found
On the Crystal and Magnetic Behavior of ScFe4Al8 Single Crystal
Nuclear and magnetic properties of the ScFe4Al8 single crystal were found to exhibit unparalleled complexity
of nuclear and magnetic structures. Our previous neutron measurements revealed presence of two modulation
vectors, both along [", ", 0], however with dfferent critical temperatures. Recent experiments forced us to revise
our knowledge of the structural ordering in the sample. So far, the crystal structure of this alloy, being of
ThMn12-type, has never been questioned
Fermiology via the electron momentum distribution
Investigations of the Fermi surface via the electron momentum distribution
reconstructed from either angular correlation of annihilation radiation (or
Compton scattering) experimental spectra are presented. The basis of these
experiments and mathematical methods applied in reconstructing
three-dimensional densities from line (or plane) projections measured in these
experiments are described. The review of papers where such techniques have been
applied to study the Fermi surface of metallic materials with showing their
main results is also done.Comment: 22 pages, 9 Figures, 4 Table
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
Degradation, Bioactivity, and Osteogenic Potential of Composites Made of PLGA and Two Different Sol–Gel Bioactive Glasses
We have developed poly(l-lactide-co-glycolide) (PLGA) based composites using sol–gel derived bioactive glasses (S-BG), previously described by our group, as composite components. Two different composite types were manufactured that contained either S2—high content silica S-BG, or A2—high content lime S-BG. The composites were evaluated in the form of sheets and 3D scaffolds. Sheets containing 12, 21, and 33 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 Young’s 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 sol–gel derived bioactive glass–PLGA composites may prove excellent potential orthopedic and dental biomaterials supporting bone formation and remodeling
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
Selected aspects of PcBN tools wear
Obróbka materiałów twardych związana jest z obróbką materiałów o twardości powyżej 50 HRC. Obróbka ta może być obróbką wykończeniową ze względu na możliwość osiągnięcia wysokiej jakości i dokładności przedmiotów obrabianych po tej operacji. Obróbka materiałów w stanie twardym lub utwardzonym związana jest z zastosowaniem specjalnych narzędzi, które są wykonane z nowych materiałów, takich jak PcBN. W artykule zaprezentowano wybrane wyniki z badań nad zużyciem narzędzi podczas obróbki toczeniem.Hard part machining is related to a process of cutting of hard materials (over 50 HRC). This process can be used as a finishing process, because of achieving high quality and accuracy of workpieces after the operation. Cutting of hard materials requires special tools, which are made of a new materials such as PcBN. This paper presents selected results of investigation under tool wear during turning of hard materials
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