Eco-friendly Elderberry based sorbent for removing Pb2+ ions from aqueous solutions

Elderberry (Sambucus nigra) pith was modified with polyethyleneimine (PEI) in order to improve the adsorption properties. Characterization of both dried Sambucus nigra pith (DSNP) and amino modification of elderberry pith with branched PEI (PEI/DSNP) was performed by: Fourier-transform infrared spectroscopy (FTIR), optical microscopy, and porosity determination. The amine and ester number, as well as acid value, were determined on DSNP and PEI/DSNP samples using standard volumetric methods. The samples were used as adsorbents for Pb2+ ions from an aqueous solution in a batch system. The obtained results were fitted using suitable equilibrium isotherm and kinetic models. The maximum adsorption capacity for Pb2+ ions on DSNP and aminаted sample, obtained using Langmuir adsorption isotherm at 298 K, are 18.9 and 47.8 mg g-1, respectively. Based on the kinetic studies, the adsorption process follows the pseudo second-order model. Thermodynamic parameters showed that the adsorption process is endothermic and spontaneous. In general, the overall adsorption process was improved by modifying starting material with branched PEI modifier by introducing large numbers of amino functionalities having high affinity to cations

Experimental observation and simulation of the equilibration of electron swarms in a scanning drift tube

We investigate the spatially and temporally resolved electron kinetics in a homogeneous electric field in argon gas, in the vicinity of an emitting boundary. This (transient) region, where the electron swarm exhibits non-equilibrium character with energy gain and loss processes taking place at separate positions (in space and time), is monitored experimentally in a scanning drift tube apparatus. Depending on the strength of the reduced electric field we observe the equilibration of the swarm over different length scales, beyond which the energy gain and loss mechanism becomes locally balanced and transport properties become spatially invariant. The evolution of the electron swarm in the experimental apparatus is also described by Monte Carlo simulations, of which the results are in good agreement with the experimental observations, over the domains of the reduced electric field and the gas pressure covered

Clinical significance of optimal red cell mass and plasma volume estimation methods

BACKGROUND: The aim of this study was to present and compare the results of proposed methods for optimal red cell mass and plasma volume (RCM&PV) estimation, and their influence on the interpretation of obtained results. MATERIAL AND METHODS: In 120/280 patients with polycythaemia rubra vera, subjected to RCM&PV determination with autologous erythrocytes in vitro labelled with 51Cr-sodium chromate, optimal volumes were determined using: 1. traditional ml/kg of: - the real body weight method (ml/kg RBW); - the optimal body weight method (ml/kg OBW). 2. the body weight, height, and sex based method (Retzlaff's tables), 3. the method recommended by the International Council for Standardization in Haematology (ICSH), based on body surface area. RESULTS: Different interpretation of the same results of 120 RCM&PV measurements was registered in 48/120 patients (40%). The greatest disagreement existed between ml/kg RBW and ml/kg OBW methods (in 39/120 subjects, 32.5%). In underweight patients the ml/kg RBW method, and in overweight patients the ml/kg OBW method, offered better agreement with ICSH&Retzlaff's methods. The ml/kg RBW method disagreed with ICSH&Retzlaff's methods and ml/kg OBW in 25% and 19.2% of patients respectively. ICSH and Retzlaff's methods disagreed in 10/120 patients (8.3%). The ICSH method yielded significantly lower optimal volumes than Retzlaff's. CONCLUSION: Three methods for optimal RCM&PV estimation lead to different interpretations of the same results of RCM&PV measurements with 51Cr-erythrocytes in 40% of patients. Two ml/kg body weight methods show greater disagreement in comparison with ICSH and Retzlaff's methods, which differ significantly. The ICSH method yields lower optimal values compared to Retzlaff's

Influence of heteropoly acids on rat synaptic plasma membrane atp -ase activity

The in vitro influence of 12-tungstosilicic acid (WSiA) and 12-tungstophosporic acid (WPA) on Na+/K+_ATPase activity, using rat synaptic plasma membrane (SPM) as a model system was investigated. The half-maximum inhibition (IC50) of the enzyme activity was achieved with 5.80⋅ 10-5mol/L of WPA and 1.17⋅10-4 mol/L of WSiA. The both examined compounds showed a dose-dependent inhibitory effect on the enzyme activity in the concentration higher than 1 μmol/L

Transport of electrons and propagation of the negative ionisation fronts in indium vapour

22 pags., 23 figs.We study the transport of electrons and propagation of the negative ionisation fronts in indium vapour. Electron swarm transport properties are calculated using a Monte Carlo simulation technique over a wide range of reduced electric fields E/N (where E is the electric field and N is the gas number density) and indium vapour temperatures in hydrodynamic conditions, and under non-hydrodynamic conditions in an idealised steady-state Townsend (SST) setup. As many indium atoms are in the first metastable state at vapour temperatures of a few thousand Kelvin, the initial Monte Carlo code was extended and generalized to consider the spatial relaxation and the transport of electrons in an idealised SST experiment, in the presence of thermal motion of the host-gas atoms and superelastic collisions. We observe a significant sensitivity of the spatial relaxation of the electrons on the indium vapour temperature and the initial conditions used to release electrons from the cathode into the space between the electrodes. The calculated electron transport coefficients are used as input for the classical fluid model, to investigate the inception and propagation of negative ionisation fronts in indium vapour at various E/N and vapour temperatures. We calculate the electron density, electric field, and velocity of ionisation fronts as a function of E/N and indium vapour temperature. The presence of indium atoms in the first metastable state significantly affects the characteristics of the negative ionisation fronts. The transition from an avalanche into a negative ionisation front occurs faster with increasing indium vapour temperature, due to enhanced ionisation and more efficient production of electrons at higher vapour temperatures. For lower values of E/N, the electron density behind the streamer front, where the electric field is screened, does not decay as one might expect for atomic gases, but it could be increased due to the accumulation of low-energy electrons that are capable of initiating ionisation in the streamer interior.The work of SD, JA, DB, MSR, DS, and BPM was sup- ˇported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, and the Institute of Physics (Belgrade). The work of KRH, OZ, and KB was supported by the United States National Science Foundation under Grant Nos. OAC-1834740, PHY-1803844, and PHY-2110023, and by the XSEDE supercomputer Allocation No. PHY-090031. The work of DVF and IB, was supported by the Australian Research Council and resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia. FB and GG acknowledge partial financial support from the Spanish Ministry MICIU (Project Nos. FIS2016-80440 and PID2019-104727-RB-C21) and CSIC (Project No. LINKA20085). This work was also financially supported by the Australian Research Council (Project No. DP180101655).Peer reviewe

Ethnobotanical knowledge and traditional use of plants in Serbia in relation to sustainable rural development

In Serbian folk tradition, hundreds of plants were used for ages as food, beverages, medicine, natural dyes, natural additives, and food preservatives, for textile and fibers, shelter and fuel, as well as for traditional customs, religious purposes, and magic. Despite being often treated as a problem for the national economy, rural areas in Serbia actually represent a huge potential, namely in richness of natural resources, i.e., (agro)biodiversity, as well as cultural and traditional heritage and related ethnobotanical knowledge. The history of health culture of the Balkan nations is very complex and interesting. The extremely long tradition of curative and prophylactic use of medicinal herbs is mentioned in the folk medical texts of both known and unknown authors. The Old Serbs had a very developed cult dedicated to certain trees and plants, where many of customs remain in place even today. Here, we discuss the most interesting, old, and autochthonous varieties of cereals, vegetables, and fruits that are still used in traditional Serbian cuisine today. This is followed with a brief review of the most commonly used medicinal herbs in Serbian folk medicine, as well as an outline of several of the best-described magical plants, including oak, basil, nettle, wormwood, linden, hawthorn, hazel tree, and laserwort

Enzymatic synthesis of galacto-oligosaccharides from whey lactose

Knežević, N., Simović, M., Bezbradica, D., Bošnjaković, J., Marinković, A., (2021) Enzymatic synthesis of galacto-oligosaccharides from whey lactose, UNIFood Conference, Belgrade, Serbie, 167

Third-order transport coefficient tensor of electron swarms in noble gases

In this work we extend a multi term solution of the Boltzmann equation for electrons in neutral gases to consider the third-order transport coefficient tensor. Calculations of the third-order transport coefficients have been carried out for electrons in noble gases, including helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe) as a function of the reduced electric field, E/n0 (where E is the electric field while n0 is the gas number density). Three fundamental issues are considered: (i) the correlation between the longitudinal component of the third-order transport tensor and the longitudinal component of the diffusion tensor, (ii) the influence of the third-order transport coefficients on the spatial profile of electron swarm, and (iii) the errors associated with the two term approximation for calculating the third-order transport coefficients for electron swarms in noble gases. It is found that a very strong correlation exists between the longitudinal components of the third-order transport coefficient tensor and diffusion tensor for the higher values of E/n0. The effects of the third-order transport coefficients on the spatial profile of electron swarms are the most pronounced for noble gases with the Ramsauer-Townsend minimum in the cross sections for elastic scattering. The largest errors of two term approximation are observed in the off-diagonal elements of the third-order transport coefficient tensor in Ar, Kr and Xe for the higher values of E/n0

Imobilizacija celulaza na polimetakrilatne nosače

Knežević, N., Bezbradica, D., Bugarčić, M., Jovanović, A., Bošnjaković, J., Marinković, A., Imobilizacija celulaza na polimetakrilatne nosače, (2021) 6. Naučno-stručni skup Politehnika, Beograd, Srbij