The aim of this paper is considering a brief historical perspective and overview of recent ideas and directions in electrochemistry in Bosnia and Herzegovina. Since the 1950s, dozens of researchers ...worked and are still working on the study of electrochemistry. The research evolved from polarography in the beginning to electrochemical deposition and/or dissolution of metals, alloys, polymers, nanocomposites and deposition of metal powders, corrosion mechanisms and corrosion protection, different catalysts and energy storage and conversion. Since the electrochemical and chemical industry was developed on the territory of today’s Bosnia and Herzegovina in the period from 1950 to the 1980s, researchers and professors were focused on the problems and challenges in the industry, not on publications. The industry was destroyed after the breakup of Yugoslavia, and names of the important researchers are very difficult to find today. That is why only a few individuals can be found on scientific databases in this period. The important validations of electrochemistry schools in Bosnia and Herzegovina are former students who are successful people in the industry or academia worldwide.
The aim of this paper is electrodeposition of Zn/CeO
2
and Zn-Mn/CeO
2
nanocomposite coatings. Four plating solutions were used (R1–R4). Solution R1 was without manganese ions, whereas solutions R2, ...R3, and R4 had Mn
2+
/Zn
2+
ratios of 1:1, 1:2, and 2:1, respectively. Electrodeposition is performed galvanostatically at 1 A dm
−2
, 2 A dm
−2
, and 4 A dm
−2
current densities with ultrasonic bath assisted mixing. The morphology of the coatings was observed using optical and scanning electron microscopy, the chemical compositions were determined using energy dispersive x-ray spectroscopy, whereas electrochemical impedance spectroscopy and potentiodynamic polarization method were used to determine the corrosion resistance of the coatings. All the solutions yield compact coatings with a small grain size and surface roughness ranging from 0.6 to 1.47 μm at all current densities. The results suggest that with the increase in current density, the content of manganese in the coating decrease, whereas the content of CeO
2
particles increases in Zn-Mn/CeO
2
coatings. Corrosion resistance of the coatings obtained from R2, R3, and R4 solutions deposited at lower current densities is higher compared to the coatings deposited from solution R1. The coating with the highest corrosion resistance was obtained from solution R2 at 1 A dm
−2
current density.
Graphical Abstract
Election data represent a precious source of information to study human behavior at a large scale. In proportional elections with open lists, the number of votes received by a candidate, rescaled by ...the average performance of all competitors in the same party list, has the same distribution regardless of the country and the year of the election. Here we provide the first thorough assessment of this claim. We analyzed election datasets of 15 countries with proportional systems. We confirm that a class of nations with similar election rules fulfill the universality claim. Discrepancies from this trend in other countries with open-lists elections are always associated with peculiar differences in the election rules, which matter more than differences between countries and historical periods. Our analysis shows that the role of parties in the electoral performance of candidates is crucial: alternative scalings not taking into account party affiliations lead to poor results.
The fast and accurate prediction of Hansen solubility benefits many diverse fields such as pharmaceuticals, the food industry, and cosmetics. To estimate the individual HSP values (polar, dispersive, ...and hydrogen bonding components), we investigated the performance of using Mordred descriptors in multiple linear regressions and XGBoost modeling. For HSP predictions, we also tested a graph-based molecular representation with graph neural network (GNN) modeling. To select the optimal models for final training and predictions, we used nested cross-validation and hyper-parameter optimization. The models with the best predictive performance were selected through internal (R2train, RMSE, MEPcv) and external (RMSEP, CCC, MEP, R2test, ar2m, Δr2m) validation metrics using ∼1200 compounds from free-available database https://www.stevenabbott.co.uk. To confirm the practical reliability, we examined the agreement of experimentally obtained HSP data from the literature for 93 compounds and the data predicted by the created models. The results of GNN modeling showed the best predictive characteristics, which include a coefficient of determination between experimentally obtained and predicted HSP values greater than 0.76 for polar and hydrogen bond forces and greater than 0.66 for dispersive forces. Interpreting the fundamental basis of Hansen solubility using the created MLR equations and XGBoost models, HSP values were found to be influenced by van der Waals volume characteristics, 2D matrix molecular representation, and polarity. We elaborated on the practical benefits of using the selected GNN method through Hansen's solubility sphere as an example. This is the first study to demonstrate the advantages of GNN in predicting individual HSP components, as well as the first study to describe in detail their molecular basis using MLR and XGBoost modeling.
Display omitted
•GNN, MLR and XGBoost modeling of three-dimensional Hansen solubility•Comparative analysis of the created QSRP models•Physico-chemical interpretation of the three-dimensional Hansen solubility•Demonstrating the practical applicability of the created models
Understanding the patterns of mobility of individuals is crucial for a number of reasons, from city planning to disaster management. There are two common ways of quantifying the amount of travel ...between locations: by direct observations that often involve privacy issues, e.g., tracking mobile phone locations, or by estimations from models. Typically, such models build on accurate knowledge of the population size at each location. However, when this information is not readily available, their applicability is rather limited. As mobile phones are ubiquitous, our aim is to investigate if mobility patterns can be inferred from aggregated mobile phone call data alone. Using data released by Orange for Ivory Coast, we show that human mobility is well predicted by a simple model based on the frequency of mobile phone calls between two locations and their geographical distance. We argue that the strength of the model comes from directly incorporating the social dimension of mobility. Furthermore, as only aggregated call data is required, the model helps to avoid potential privacy problems.
Display omitted
•Ovomucoid CSP showed enantioselectivity for the separation of timolol enantiomers.•An enantioselective HPLC method was developed using AQbD methodology.•Achievement of a more ...ecologically friendly method than official one.•The validation studies confirmed adequacy of the method for its intended purpose.
Official method in Ph. Eur. for evaluation of timolol enantiomeric purity is normal-phase high performance liquid chromatography (NP-HPLC) method. Compared to other HPLC modes, NP is depicted as quite expensive with high consumption of organic solvents which leads to chronic exposure of analysts to toxic and carcinogenic effects. In order to overcome above-mentioned drawbacks, the aim of this study was to develop new method with better eco-friendly features. This was enabled by using protein type Chiral Stationary Phase (CSP) in reversed-phase mode that required up to 10 % (v/v) of organic solvent. Therefore, an enantioselective HPLC method was developed and validated for quantification of (S)-timolol and its chiral impurity, (R)-isomer. Optimized separation conditions on ovomucoid column were set using Analytical Quality by Design (AQbD) approach in method development. Optimization step was performed following the Box-Behnken experimental plan and the influence of three critical method parameters (CMPs) towards enantioseparation of the above-mentioned peak pair was examined. CMPs included variation of acetonitrile content in the mobile phase (5–10 %, v/v), pH value of the aqueous phase (6.0–7.0) and ammonium chloride concentration in the aqueous part of the mobile phase (10−30 mmol L−1). The most relevant critical method attributes (CMAs) in this case were the separation criterion between studied critical pair and retention factor of the second eluting peak, (S)-timolol. Qualitative Design Space (DS) was defined by Monte Carlo simulations providing adequate assurance of method’s qualitative robustness (π = 95 %). The selected working point situated in the middle of the DS was characterized by following combination of CMPs: acetonitrile content in the mobile phase 7 % (v/v), pH value of the aqueous phase 6.8 and concentration of ammonium chloride in aqueous phase 14 mmol L–1. In the next step, the quantitative robustness was tested by Plackett-Burman experimental design. The validation studies confirmed adequacy of the proposed method for its intended purpose. Finally, Analytical Eco-Scale metric tool was applied to confirm that developed method represents excellent green analytical method compared to the official one.
Collective knowledge as a social value may arise in cooperation among actors whose individual expertise is limited. The process of knowledge creation requires meaningful, logically coordinated ...interactions, which represents a challenging problem to physics and social dynamics modeling. By combining two-scale dynamics model with empirical data analysis from a well-known Questions &Answers system Mathematics, we show that this process occurs as a collective phenomenon in an enlarged network (of actors and their artifacts) where the cognitive recognition interactions are properly encoded. The emergent behavior is quantified by the information divergence and innovation advancing of knowledge over time and the signatures of self-organization and knowledge sharing communities. These measures elucidate the impact of each cognitive element and the individual actor's expertise in the collective dynamics. The results are relevant to stochastic processes involving smart components and to collaborative social endeavors, for instance, crowdsourcing scientific knowledge production with online games.
PDF
