Computing the eccentric-distance sum for graph operations

In this paper, we present explicit formulas for computing the eccentric-distance sum of the most important graph operations such as the Cartesian product, join, composition, disjunction, symmetric difference, cluster and corona product of graphs. Also, we apply our results to compute this eccentricity-related invariant for some important classes of molecular graphs and nano-structures by specializing components of these graph operations.     

Excess molar volume and viscosity deviation for binary mixtures of polyethylene glycol dimethyl ether 250 with 1,2-alkanediols (C3–C6) at T = (293.15 to 323.15) K

In this work, density and viscosity have been determined for (polyethylene glycol dimethyl ether 250 + 1,2-propanediol, or 1,2-butanediol, or 1,2-pentanediol, or 1,2-hexanediol) binary systems over the whole concentration range at temperatures of (293.15, 303.15, 313.15, 323.15) K and atmospheric pressure. Experimental data of mixtures were used to calculate the excess molar volumes V^E, and viscosity deviations Δη. These results were fitted by the Redlich–Kister polynomial relation to obtain the coefficients and standard deviations.     

Predicting cortical oscillations with bidirectional LSTM network: a simulation study

It has been stated that up-down-state (UDS) cortical oscillation levels between excitatory and inhibitory neurons play a fundamental role in brain network construction. Predicting the time series behaviors of neurons in periodic and chaotic regimes can help in improving diseases, higher-order human activities, and memory consolidation. Predicting the time series is usually done by machine learning methods. In paper, the deep bidirectional long short-term memory (DBLSTM) network is employed to predict the time evolution of regular, large-scale UDS oscillations produced by a previously developed neocortical network model. In noisy time-series prediction tasks, we compared the DBLSTM performance with two other variants of deep LSTM networks: standard LSTM, LSTM projected, and gated recurrent unit (GRU) cells. We also applied the classic seasonal autoregressive integrated moving average (SARIMA) time-series prediction method as an additional baseline. The results are justified through qualitative resemblance between the bifurcation diagrams of the actual and predicted outputs and quantitative error analyses of the network performance. The results of extensive simulations showed that the DBLSTM network provides accurate short and long-term predictions in both periodic and chaotic behavioral regimes and offers robust solutions in the presence of the corruption process.

     

Direct oxidative synthesis of nitrones from aldehydes and primary anilines using graphite oxide and Oxone

One-pot condensation/oxidation of aldehydes and primary anilines into nitrones using graphite oxide (GO) and Oxone as the oxidant under very mild reaction conditions is described. The proposed method provides a direct oxidative synthesis of various nitrones in good to excellent yields under metal-free conditions in short reaction times.     

An efficient regioselective synthesis of highly functionalized 3-oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidines via an isocyanide-based three-component reaction

We present a novel, convenient, and efficient method for synthesizing polysubstituted 3-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidines via a three-component reaction. The zwitterions generated from the reaction of isocyanides and dialkyl acetylenedicarboxylates react with 2-imino-1,3-thiazolidin-4-one to produce the title compounds in good yields.     

Ionophore Properties of Schiff Base Compounds as Ion Sensing Molecules for Fabricating Cu(II) Ion-Selective Electrodes

Bis(2-hydroxybenzaldehyde)-1,2-diaminoethane (L^I), bis(2-hydroxybenzaldehyde)-1,3-diaminopropane (L^II) and bis(2-hydroxybenzaldehyde)-4,4'-methylendianiline (L^III) were examined as ionophores for fabrication of polyvinylchloride (PVC) membrane Cu(II) ion-selective potentiometric sensors. The optimum composition (%) for the sensors was: 5 L^I, 30 PVC, 6 sodium tetraphenylborate (NaTPB), 59 ortho-nitrophenyloctyl ether (NPOE); 4 L^II, 30 PVC, 5 NaTPB, 61 dibutyl phthalate; 6 L^III, 30 PVC, 5 NaTPB, 59 NPOE. The linear response range of the electrodes was 5 × 10^–4–0.05 (L^I), 5 × 10^–4–0.1 (L^II) and 1 × 10^–6–0.01 M (L^III), and the corresponding detection limits were 4 × 10^–4, 4 × 10^–4 and 2 × 10^–7 M, respectively. The sensors were showed rapid response time (≈10 s). Their responses were independent on pH in the range 2.5–5.0 (L^I), 3.2–4.7 (L^II) and 4.0–5.0 (L^III). The selectivity of the prepared electrodes towards copper ions over some mono-, di- and trivalent metal ions was evaluated. The sensors were used as indicator electrode in potentiometric titration of copper ions in aqueous solutions.     

Green synthetic approach toward new chromeno[4,3-b]quinoline and chromeno[4,3-b]pyridine derivatives

Chemistry of Heterocyclic Compounds - A facile, convenient, and efficient synthesis of new chromeno[4,3-b]quinoline and chromeno[4,3-b]pyridine derivatives has been accomplished via one-pot...     

Optimization of modification condition of nano-kaoline as an adsorbent for textile dye removal

In this study, adsorption capacity of textile red dye on alkylated kaolin was investigated through batch mode. Accordingly, raw kaolin was alkylated via NaOH treatment. The work was carried out in two steps. At first step, the effect of various alkylation conditions of kaolin on its dye adsorption performance was studied using the model equation designed by 2-level factorial design. Three factors were changed in two level including NaOH solution temperature (45–75°C), mixing time (3–24 h), and NaOH solution concentration (0.1–2 M). The resultant model showed 91% of the variability in data used to fit dye adsorption capacity values. However, the analysis of variance revealed that the fitted model is high significant. Based on the predicting model, the optimal alkylation conditions with desirability factor of 0.911 were obtained at temperature of 75°C, NaOH concentration of 0.1 M and after 24 h mixing. At step two, chemical content, bonds and functional groups of the treated kaolin, which was prepared based on the optimum condition and compared with the raw kaolin via X-ray fluorescence (XRF) analysis and Fourier transform infrared analysis (FTIR). The results show slight reduction in SiO₂ content. Finally, the adsorption capacity of dye on both treated and raw kaolin was investigated.