Dipolar depletion effect on the differential capacitance of carbon based materials

The remarkably low experimental values of the capacitance data of carbon based materials in contact with water solvent needs to be explained from a microscopic theory in order to optimize the efficiency of these materials. We show that this experimental result can be explained by the dielectric screening deficiency of the electrostatic potential, which in turn results from the interfacial solvent depletion effect driven by image dipole interactions. We show this by deriving from the microscopic system Hamiltonian a non-mean-field dipolar Poisson-Boltzmann equation. This can account for the interaction of solvent molecules with their electrostatic image resulting from the dielectric discontinuity between the solvent medium and the substrate. The predictions of the extended dipolar Poisson-Boltzmann equation for the differential capacitance are compared with experimental data and good agreement is found without any fitting parameters

IgA-BEM for 3D Helmholtz problems using conforming and non-conforming multi-patch discretizations and B-spline tailored numerical integration

An Isogeometric Boundary Element Method (IgA-BEM) is considered for the numerical solution of Helmholtz problems on 3D bounded or unbounded domains, admitting a smooth multi-patch representation of their finite boundary surface. The discretization spaces are formed by C0 inter-patch continuous functional spaces whose restriction to a patch simplifies to the span of tensor product B-splines composed with the given patch NURBS parameterization. Both conforming and non-conforming spaces are allowed, so that local refinement is possible at the patch level. For regular and singular integration, the proposed model utilizes a numerical procedure defined on the support of each trial B-spline function, which makes possible a function-by-function implementation of the matrix assembly phase. Spline quasi-interpolation is the common ingredient of all the considered quadrature rules; in the singular case it is combined with a B-spline recursion over the spline degree and with a singularity extraction technique, extended to the multi-patch setting for the first time. A threshold selection strategy is proposed to automatically distinguish between nearly singular and regular integrals. The non-conforming C0 joints between spline spaces on different patches are implemented as linear constraints based on knot removal conditions, and do not require a hierarchical master-slave relation between neighbouring patches. Numerical examples on relevant benchmarks show that the expected convergence orders are achieved with uniform discretization and a small number of uniformly spaced quadrature nodes

PTHrP Induces Autocrine/Paracrine Proliferation of Bone Tumor Cells through Inhibition of Apoptosis

Giant Cell Tumor of Bone (GCT) is an aggressive skeletal tumor characterized by local bone destruction, high recurrence rates and metastatic potential. Previous work in our lab has shown that the neoplastic cell of GCT is a proliferating pre-osteoblastic stromal cell in which the transcription factor Runx2 plays a role in regulating protein expression. One of the proteins expressed by these cells is parathryroid hormone-related protein (PTHrP). The objectives of this study were to determine the role played by PTHrP in GCT of bone with a focus on cell proliferation and apoptosis. Primary stromal cell cultures from 5 patients with GCT of bone and one lung metastsis were used for cell-based experiments. Control cell lines included a renal cell carcinoma (RCC) cell line and a human fetal osteoblast cell line. Cells were exposed to optimized concentrations of a PTHrP neutralizing antibody and were analyzed with the use of cell proliferation and apoptosis assays including mitochondrial dehydrogenase assays, crystal violet assays, APO-1 ELISAs, caspase activity assays, flow cytometry and immunofluorescent immunohistochemistry. Neutralization of PTHrP in the cell environment inhibited cell proliferation in a consistent manner and induced apoptosis in the GCT stromal cells, with the exception of those obtained from a lung metastasis. Cell cycle progression was not significantly affected by PTHrP neutralization. These findings indicate that PTHrP plays an autocrine/paracrine neoplastic role in GCT by allowing the proliferating stromal cells to evade apoptosis, possibly through non-traditional caspase-independent pathways. Thus PTHrP neutralizing immunotherapy is an intriguing potential therapeutic strategy for this tumor

Hysteresis in Pressure-Driven DNA Denaturation

In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue

Data of temporal and seasonal variations of silicate Svratka River and sediment characterization, Czech Republic: geochemical and stable isotopic approach

We hypothesize that the Svratka River is polluted, therefore we applied mineralogical e.g. XRD, XRF and isotopic methods to evaluate its ecological state. The major solute composition of the Svratka River is dominated by HCO3-, Ca2+, Na+, Mg2+, K+ and Cl-. d13CDIC range from -13.3 ‰ to -8.0 ‰ and was used to evaluate biogeochemical processes in river water: (1) exchane with atmospheric CO2 and (2) soil CO2 originating from degradation of organic matter. Higher d15N (around 10 ‰) values are attributed to application of fertilizers in the watershed. X-ray diffraction revealed positive correlation of Al with K and Rb, which show that quartz, feldspars and muskovite are dominant minerals in river system. Weathering of these minerals within the watershed contributes to total alkalinity and solute composition of river water. Calculated enrichment factors for zinc and lead were found at lower reaches of the river.Data were gathered from competent athorities, field work and laboratory work. Data were used to calculate weathering intensity. Data are useful to provide background information on aquatic geochemistry in case of future management of the Svratka River system and other rivers worlwide.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Data set on petrological and isotopic composition of some selected lignites, sub-bituminous and ortho-bituminous coals

We present a dataset of petrological characteristics, isotopic composition of carbon (δ13C), and nitrogen (δ15N) in thirty-two coal samples originating from six diverse sedimentary coal basins: Velenje Basin (Slovenia), Laško syncline (Slovenia), Mura-Zala Basin (Slovenia), Istrian Basin (Croatia), Sokolov Basin (Czeck Republic), and Barito Basin (India). These coal samples were obtained from open-pit mines, underground mining areas, and boreholes. Additionally, one coal sample sourced from Indonesia and extracted by the Kideco Company was specifically obtained from Termoelektrarna Toplarna Ljubljana.Before conducting stable isotope analyses (δ13C and δ15N) on various coal samples, the samples were macroscopically determined according to the ECE-UN (1998) classification in terms of ortho-lignite, meta-lignite, sub-bituminous coal, and bituminous coal. The stable isotope composition of organic carbon (δ13Corg.) and nitrogen (δ15Nbulk) in different lignite lithotypes was analyzed using the PDZ Europa 20-20 isotope-ratio mass spectrometer (Sercon Ltd, UK) connected to an ANCA-SL preparation module.The carbon isotopic composition (δ13Corg.) of the samples ranged from -27.9 to -23.6 ‰, while the nitrogen isotopic composition (δ15N) ranged from 1.8 to 7.4 ‰. Higher δ13Corg. values and elevated δ15N values indicate greater bacterial degradation of organic matter. The Raša coals, classified as vitrain samples and formed in an anaerobic marine environment, exhibited the highest δ13Corg. values in the range of -24.0 to -23.6 ‰. The highest δ15N value of 7.4 ‰ (indicating higher mineralization) was detected in a lignite sample from the Velenje Basin. The lowest δ15N value of 1.8 ‰ was observed in Jožef coal sample from the Sokolov Basin, indicating minimal mineralization of organic matter. Further, we compared δ13Corg and δ15N data of plants and coals gathered in this study with previously published data to evaluate microbial degradation. We obtained no correlation between δ13C and δ15N. Moreover, we calculated δ13C in air to determine differences in paleoclimate between coals. The determined δ13C values fall within the typical range of world coal (from -20.9 to -30.7 ‰). Calculated δ13CCO2 ranges from -8.4‰ to -3.4 ‰, which is more positive compared to modern atmospheric CO2 with -8.5 ‰.In conclusion, δ13C and δ15N data, in association with the petrological composition, could be used in paleoenvironmental, paleoclimate, and paleoecology studies, as well as for the clarification of biogeochemical processes in sedimentary basins.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Data set on petrological and isotopic composition of some selected lignites, sub-bituminous and ortho-bituminous coals

We present a dataset of petrological characteristics, isotopic composition of carbon (δ13C), and nitrogen (δ15N) in thirty-two coal samples originating from six diverse sedimentary coal basins: Velenje Basin (Slovenia), Laško syncline (Slovenia), Mura-Zala Basin (Slovenia), Istrian Basin (Croatia), Sokolov Basin (Czeck Republic), and Barito Basin (India). These coal samples were obtained from open-pit mines, underground mining areas, and boreholes. Additionally, one coal sample sourced from Indonesia and extracted by the Kideco Company was specifically obtained from Termoelektrarna Toplarna Ljubljana.Before conducting stable isotope analyses (δ13C and δ15N) on various coal samples, the samples were macroscopically determined according to the ECE-UN (1998) classification in terms of ortho-lignite, meta-lignite, sub-bituminous coal, and bituminous coal. The stable isotope composition of organic carbon (δ13Corg.) and nitrogen (δ15Nbulk) in different lignite lithotypes was analyzed using the PDZ Europa 20-20 isotope-ratio mass spectrometer (Sercon Ltd, UK) connected to an ANCA-SL preparation module.The carbon isotopic composition (δ13Corg.) of the samples ranged from -27.9 to -23.6 ‰, while the nitrogen isotopic composition (δ15N) ranged from 1.8 to 7.4 ‰. Higher δ13Corg. values and elevated δ15N values indicate greater bacterial degradation of organic matter. The Raša coals, classified as vitrain samples and formed in an anaerobic marine environment, exhibited the highest δ13Corg. values in the range of -24.0 to -23.6 ‰. The highest δ15N value of 7.4 ‰ (indicating higher mineralization) was detected in a lignite sample from the Velenje Basin. The lowest δ15N value of 1.8 ‰ was observed in Jožef coal sample from the Sokolov Basin, indicating minimal mineralization of organic matter. Further, we compared δ13Corg and δ15N data of plants and coals gathered in this study with previously published data to evaluate microbial degradation. We obtained no correlation between δ13C and δ15N. Moreover, we calculated δ13C in air to determine differences in paleoclimate between coals. The determined δ13C values fall within the typical range of world coal (from -20.9 to -30.7 ‰). Calculated δ13CCO2 ranges from -8.4‰ to -3.4 ‰, which is more positive compared to modern atmospheric CO2 with -8.5 ‰.In conclusion, δ13C and δ15N data, in association with the petrological composition, could be used in paleoenvironmental, paleoclimate, and paleoecology studies, as well as for the clarification of biogeochemical processes in sedimentary basins.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Spatial and seasonal variations in delta18O and deltaD values in the River Sava in Slovenia.

Stable isotope measurements of oxygen and hydrogen (delta18O and deltaD) in stream waters and precipitation were used to investigate hydrological pathways and residence times in the River Sava catchment in Slovenia. delta18O and deltaD values of precipitation exhibited strong seasonal variations. Precipitation is of mixed Atlantic–Mediterranean origin which is also reflected in the isotopic composition of River Sava surface waters. The isotopic content of the river water is dependent on temperature, elevation of the recharge area and amount of precipitation. Spatially, rivers water is 16O-enriched in the high mountain areas due to higher amount of precipitation, lower temperature and higher elevation of the recharge area, while in the lower part of the River Sava catchments the delta18O values are higher. It is also observed that the River Sava responds quickly to precipitation which is reflected in its delta18O and deltaD values and the low residence time estimated in the river. Using an exponential flow model it was calculated that mean stream water residence times varied between 0.4 and 2.1 years. The shortest residence time determined at Savica is connected mainly to the higher amount of precipitation in the upper Sava watershed and the mountains carbonate karst terrain characterized by a higher runoff. The mean residence time in the main stream water of the River Sava was estimated to be 1.32 years and is in a good agreement with the residence time determined using 3H measurements. These data extend our knowledge in understanding the hydrological cycle of the River Sava, the interactions between precipitation, surface water and groundwater and, at the same time, demonstrate the utility of isotope tracers in determining catchments characteristics