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Vertical graphene (VG) is one of the newest forms of graphite, being part of the family of carbon materials. Due to its unique characteristics and physiochemical properties including large specific surface area, high electric conductivity and intense electrochemical activity, it has attracted the interest in many applications, specifically in the medical field. VG is a two-dimensional graphitic sheet, vertically aligned to the substrate. Its electrical characteristics make VG a good choice for using it in the development of electrochemical biosensors for cellular identification. VG is obtained using plasma enhanced chemical vapor deposition. Scanning electron microscopy was used to study the morphological structure of the grown vertical graphene, Raman spectroscopy was performed to identify the characteristic vibrational modes and to assess the quality of the deposited films and electrochemical impedance spectroscopy was used for electrical characterization of the vertical graphene. In order to assess the biological effect of VG samples and to confirm that the VG can be used for cellular identification, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium-salt assay was used on a cell line of U251 human glioblastoma (CLS). [ABSTRACT FROM AUTHOR]

The study aimed to analyze and characterize an urban area based on satellite imagery. UAT Dumbravita, Timis County, Romania, was studied under the aspect of the variation of NDBI and NDVI indices. It was considered a period of four years, 2017 - 2020, for the study, and as the period of the year the summer season was taken into account. Satellite scenes, Landsat 8, were used, taken in July - August during the study period. Based on spectral information and established formulas, NDBI and NDVI indices were calculated. Data sets of 21011 were analyzed for each index calculated and year of study. The series of values of the two indices studied (NDBI, NDVI) presented statistical distributions of histogram type - normal fit. The ANOVA test evaluated and confirmed the data safety and the presence of the variance in the data series (F>Fcrit, p<0.001). According to the Diversity profile, NDVI presented a higher variation in 2020 and a lower one in 2018. Intermediate values were recorded for 2017 and 2019. The variation of NDVI index values in relation to NDBI during the study period was described by 2nd order polynomial equations for 2017 and 2018 in statistical safety conditions (R² = 0.729, p <0.001, F = 28287 for 2017; R² = 0.773, p <0.001 F = 35695 for 2018). In the conditions of 2019 and 2020, the NDVI variation in relation to NDBI was best described by linear equations, in conditions of statistical safety (R² = 0.716, p <0.001, F = 53038 for 2019; R² = 0.798, p < 0.001, F = 83229 for the year 2020). The general analysis over the study period, mean values of NDBI and NDVI indices, led to a spline model, which most appropriately described, and in statistical safety, the NDVI variation relative to NDBI. [ABSTRACT FROM AUTHOR]

Three phase change paraffinic materials (PCMs) were thermophysically (phase-transition temperatures, latent heat, heat capacity at constant pressure, density, and thermal conductivity) investigated in order to be used as latent heat storage media in a pilot plant developed in Plovdiv Bulgaria. Raman structural investigation probes aliphatic character of the E53 sample, while the E46 and ECP samples contain also unsaturated components due to their Raman features within 1,500-1,700 cm range. Orthorhombic structure of the three PCMs was evidenced by the Raman modes at the 1,417 cm. The highest latent heat value, Δ H, of phase transitions among the three materials was represented by summation of a solid order-disorder, and melting latent heat was encountered by the E53 paraffin, i.e., 194.32 J g during a μ-DSC scan of 1 °C min. Conversely, the ECP composite containing ceresin component shows the lowest latent heat value of 143.89 J g and the highest thermal conductivity of 0.46 W m K among the three phase change materials (PCMs). More facile melt-disordered solid transition with the activation energy of 525.45 kJ mol than the lower temperature transition of disorder-order ( E of 631.73 kJ mol) during the two-step process of solidification for the E53 melt are discussed in terms of structural and molecular motion changes. [ABSTRACT FROM AUTHOR]

The SANS facility existing at the Pitesti 14MW TRIGA reactor is presented. The main characteristics and the preliminary evaluation of the installation performances are given. A monochromatic neutron beam with 1.5 Å ≤ λ ≤ 5 Å is produced by a mechanical velocity selector with helical slots. A fruitful partnership was established between INR Pitesti (Romania) and JINR Dubna (Russia). The first step in this cooperation consists in the manufacturing in Dubna of a battery of gas-filled positional detectors devoted to the SANS instrument. [ABSTRACT FROM AUTHOR]