Spectroscopic studies of the hydrogen bonded charge transfer complex of 2-aminopyridine with π-acceptor chloranilic acid in different polar solvents

Hydrogen bonded charge transfer complex (HBCT) between 2-aminopyridine (2AP) as electron donor, hydrogen bond acceptor, with chloranilic acid (CHA) as the π-electron acceptor, hydrogen bond donor, has been studied spectrophotometrically in the polar solvents acetonitrile (AN), methanol (MeOH) and ethanol (EtOH). The stoichiometry of the complex has been identified by Job's and photometric titration methods to be 1:1. The Benesi-Hildebrand equation has been applied to estimate the formation constant (K_CT) and molar extinction coefficient (ε). It was found that the value of K_CT is larger in methanol than those in acetonitrile or ethanol. The results were interpreted in terms of Kamlet-Taft α and β solvent parameters. Furthermore, the data were analyzed in terms of standard free energy change (ΔG°), oscillator strength (f), dissociation energy (W), transition dipole moment (μ) and ionization potential (I_P). Also, the solid HBCT-complex was synthesized and characterized by using elemental analysis and FTIR spectroscopy.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

Design and evaluation of synthetic silica-based monolithic materials in shrinkable tube for efficient protein extraction

Sample pretreatment is a required step in proteomics in order to remove interferences and preconcentrate the samples. Much research in recent years has focused on porous monolithic materials since they are highly permeable to liquid flow and show high mass transport compared with more common packed beds. These features are due to the micro-structure within the monolithic silica column which contains both macropores that reduce the back pressure, and mesopores that give good interaction with analytes. The aim of this work was to fabricate a continuous porous silica monolithic rod inside a heat shrinkable tube and to compare this with the same material whose surface has been modified with a C(18) phase, in order to use them for preconcentration/extraction of proteins. The performance of the silica-based monolithic rod was evaluated using eight proteins; insulin, cytochrome C, lysozyme, myoglobin, β-lactoglobulin, ovalbumin, hemoglobin, and bovine serum albumin at a concentration of 60 μM. The results show that recovery of the proteins was achieved by both columns with variable yields; however, the C(18) modified silica monolith gave higher recoveries (92.7 to 109.7%) than the non-modified silica monolith (25.5 to 97.9%). Both silica monoliths can be used with very low back pressure indicating a promising approach for future fabrication of the silica monolith inside a microfluidic device for the extraction of proteins from biological media.     

Spectrophotometric determination of carbamazepine and mosapride citrate in pure and pharmaceutical preparations

Simple, rapid and sensitive spectrophotometric methods were developed for the determination of carbamazepine and mosapride citrate drugs in pure and pharmaceutical dosage forms. These methods are based on ion pair and charge transfer complexation reactions. The first method is based on the reaction of the carbamazepine drug with Mo(V)–thiocyanate in hydrochloric acid medium followed by an extraction of the coloured ion-pair with 1,2-dichloroethane and the absorbance of the ion pair was measured at 470 nm. The second method is based on the formation of ion-pairs between mosapride citrate and two dyestuff reagents namely bromothymol blue (BTB) and bromocresol green (BCG) in a universal buffer of pH 4 and 3, respectively. The formed ion-pairs are extracted with chloroform and methylene chloride and measured at 412 and 416 nm for BTB and BCG reagents, respectively. The third method is based on charge transfer complex formation between mosapride citrate (electron donor) and DDQ (π-acceptor reagent) and the absorbance of the CT complexes was measured at 450 nm. All the optimum conditions are established. The calibration graphs are rectilinear in the concentration ranges 10–350 for carbamazepine using Mo(V)–thiocyanate and 4–100, 4–60 and 10–150 μg mL^?1 for mosapride citrate using BTB, BCG and DDQ reagents, respectively. The Sandell sensitivity (S), molar absorptivity, correlation coefficient, regression equations and limits of detection (LOD) and quantification (LOQ) are calculated. The law values of standard deviation (0.04–0.09 for carbamazepine using Mo(V)–thiocyanate and 0.022–0.024, 0.013–0.018 and 0.013–0.020 for mosapride citrate using BTB, BCG and DDQ, respectively) and relative standard deviation (0.630–2.170 for carbamazepine using Mo(V)–thiocyanate and 0.123–1.43, 0.102–0.530 and 0.226–1.280 for mosapride citrate using BTB, BCG and DDQ, respectively) reflect the accuracy and precision of the proposed methods. The methods are applied for the assay of the two investigated drugs in pharmaceutical dosage forms. The results are in good agreement with those obtained by the official method.     

Parasitological and Biochemical Efficacy of the Active Ingredients of Allium sativum and Curcuma longa in Schistosoma mansoni Infected Mice

The active ingredients allicin and curcumin have a wide range of actions against fungi, bacteria, and helminths. Therefore, the study was aimed to evaluate the efficacy of allicin (AL) and curcumin (CU) as antischistosomal drugs and their biochemical effects in normal and Schistosoma mansoni-infected mice. Praziquantel (PZQ) was administrated for two successive days while AL or CU was given for two weeks from the week 7th postinfection (PI). The possible effect of different regimens on Schistosoma worms was evaluated by measuring the percentage of the recovered worms, tissue egg load, and oogram pattern. Serum alanine transaminase activity and levels of triglycerides, cholesterol, and uric acid were measured. Liver tissue malondialdehyde and reduced glutathione levels besides, the activities of glutathione-S-transferase, superoxide dismutase and catalase were assessed for the oxidative/antioxidant condition. DNA electrophoresis of liver tissue was used to indicate the degree of fragmentation. There was a significant reduction in the recovered worms and egg load, with a marked change of oogram pattern in all treated groups with PZQ, AL, and CU in comparison with infected-untreated mice. PZQ, AL, and CU prevented most of the hematological and biochemical disorders, as well as significantly improved the antioxidant capacity and enhanced DNA fragmentation in the liver tissue of schistosomiasis mice compared to the infected-untreated group. These promising results suggest that AL and CU are efficient as antischistosomal drugs, and it would be beneficial to test their combination to understand the mechanism of action and the proper period of treatment leading to the best result.     

Asymptotic analysis for the eikonal equation with the dynamical boundary conditions

We study the dynamical boundary value problem for Hamilton‐Jacobi equations of the eikonal type with a small parameter. We establish two results concerning the asymptotic behavior of solutions of the Hamilton‐Jacobi equations: one concerns with the convergence of solutions as the parameter goes to zero and the other with the large‐time asymptotics of solutions of the limit equation.     

New thieno[2,3-d]pyrimidine derivatives as EGFRWT and EGFRT790M inhibitors: Design,synthesis, antiproliferative activities,docking studies,ADMET, toxicity,MD simulation studies

A series of thieno[2,3-d]pyrimidines were designed and synthesized as epidermal growth factor receptor (EGFR) inhibitors. These compounds were tested for their ability to inhibit MCF-7 and A549 cancer cells. The most active compound, 12c , inhibited the growth of both cell lines, with IC₅₀ values of 15.67 and 12.16 μM, respectively. It was found that 12c had inhibitory effects on both EGFR^WT and EGFR^T790M isoforms, with inhibitory partialities of 37.50 and 148.90 nM, respectively. Additionally, 12c was found to be safer than erlotinib against normal cell lines (IC₅₀ = 38.61 μM). Compound 12c induced early and late apoptosis in A549 cells and arrested cell growth at G1 and G2/M phases. 12c was also found to increase caspases 3 and 8 ratios. Molecular docking indicated the correct binding modes of the synthesized compounds. MD simulations, MM-GBSA, and PLIP studies confirmed the precise binding of 12c to the EGFR protein over 100 ns.     

Unexpected radiation hazard in dyes of textiles

Textile dyes are among the most problematic pollutants because of their toxicity on several organisms and ecosystems. Many of the chemicals used in the textile industry may represent some health concerns. The determination of the radioactivity in textile dyes is therefore very important for both human health and environment. The study was designated to determine, for the first time, the values of ²³⁸U, ²³²Th and ⁴⁰K in nine different dyes employed in the textile industry using gamma spectrometry with a Hyper Pure Germanium (HPGe) detector. The mean activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K were 29.37?±?4.48, 1.15?±?0.13 and 565?±?4 Bq/kg, respectively. The calculated radium equivalents for all samples were lower than the maximum admissible value (370 Bq/kg). The absorbed dose rates due to the natural radioactivity of the investigated samples ranged from 2.94?±?0.05 to 166?±?3 nGy/h. So, the absorbed dose rates for all samples of textile dyes were lower than the international recommended value (55 nGy/h) except the yellow dye (166?±?3 nGy/h), which recorded a significant radiological hazard. The external hazard index was also calculated. Conclusively, the results have indicated that the textile dyes may possess a measurable amount of radioactivity that should be taken into account. Therefore, safety rules and precautions should be applied for dyes used in the textile industry and for people working in this field.     

A Markovian queueing model for ambulance offload delays

Ambulance offload delays are a growing concern for health care providers in many countries. Offload delays occur when ambulance paramedics arriving at a hospital Emergency Department (ED) cannot transfer patient care to staff in the ED immediately. This is typically caused by overcrowding in the ED. Using queueing theory, we model the interface between a regional Emergency Medical Services (EMS) provider and multiple EDs that serve both ambulance and walk-in patients. We introduce Markov chain models for the system and solve for the steady state probability distributions of queue lengths and waiting times using matrix-analytic methods. We develop several algorithms for computing performance measures for the system, particularly the offload delays for ambulance patients. Using these algorithms, we analyze several three-hospital systems and assess the impact of system resources on offload delays. In addition, simulation is used to validate model assumptions.     

On difference of two monotone operators

In this paper, we introduce and consider the problem of finding zeroes of difference of two monotone operators in a Hilbert space. Using the resolvent operator technique, we show that this problem is equivalent to the fixed point problem. This equivalence is used to suggest and analyze an iterative method for finding a zero of difference of two monotone operators. We also discuss the convergence of the iterative method under suitable conditions. Our method of proof is very simple as compared with other techniques.