Synthesis,Characterization, Speciation,and Biological Studies on Metal Chelates of Carbohydrates with Molecular Docking Investigation

The role of starch aerogel (St-AG) and carboxymethyl cellulose (CMC) as biolgical active compounds, when they subjected for complexation with metal ions, is assessed in this work. The complexation is carried out with palladium(II) and copper(II) ions, in solid state. Different tools of analysis are carried out to characterize and elucidate the structures of these complexes, namely: elemental analysis, IR, thermal analysis, magnetic measurement and molar conductance techniques. All synthesized complexes are formed with 1:2 (metal:ligand) stoichiometry except the case of aerogel starch 1:1 (Pd:starch). All isolated complexes show a satisfactory cytotoxic effect results against colon cancer cell lines HCT11. Additionally, these complexes are screened for their antibacterial activities against two types of Gram positive and negative bacteria. Molecular docking investigation confirmed the cytotoxicity and antibacterial results. Proton–ligands association constants and their complex formation constants with some bivalent metal ions, using potentiometric method show that the complexes formed in solution have a stoichiometry of 1:1 [metal:ligand]. The effects of metal ion, ionic radius, electronegativity and nature of ligand on the formation constants are discussed. The formation constants of the complexes with 3D transition metals followed the order Mn²⁺ < Co²⁺ < Ni²⁺ < Cu²⁺ > Zn²⁺.     

Novel polymaleimide containing dibenzoyl hydrazine pendant group as chelating agent for antimicrobial activity

Novel polymaleimide containing dibenzoyl hydrazine pendant group, poly[N-benzoyl-4-(N-maleimido)-phenyl hydrazide], and its metal complexes have been synthesized. Their antimicrobial activity against Bacillus subtilis, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Escherichia coli bacteria and that against Aspergillus fumigatus, Syncephalastrum racemosum, Geotrichum candidum, and Candida albicans fungi were investigated. The polymer–metal complexes showed better antimicrobial activity than that of the parent polymer. The inhibition of the growth of the microbes remarkably depends on the type of the metal in the complexes. The polymer–Co(II) and the polymer–Cd(II) complexes are more potent in inhibition of the tested microbes growth than the rest of the prepared complexes.     

Potential of Ozonated Water at Different Temperatures to Improve Safety and Shelf-Life of Fresh Cut Lettuce

The present study was carried out to determine the effect of ozonated water (2 mg L^?1) at different temperatures (4 °C and 15 °C) on the microbiological, color and sensory properties of lettuce. Cold ozone treatment (4 °C) significantly reduced the natural background microflora of lettuce. Salmonella Typhimurium and Escherichia coli inoculated on lettuce samples were insignificantly influenced by the temperature of water. During storage period at +4 °C for 14 days, the highest quality was observed from the samples treated with cold ozonated water. Ozone treatments did not affect the color properties and sensory quality of lettuce samples.     

Comparison of mechanical properties of heat‐polymerized acrylic resin with silver nanoparticles added at different concentrations and sizes

The aim of this study was to investigate the effect of silver nanoparticles (AgNPs) incorporation on the flexural strength (FS) of poly(methyl methacrylate) (PMMA). PMMA specimens (65 mm × 10 mm × 3.3 mm for flexural test, 50 mm × 6 mm × 4 mm for impact test) containing different sizes (40, 50, 60 nm) and concentrations (0.05%, 0.2%) of AgNPs were prepared, along with a control group with no AgNP. Impact strength (IS) and FS of all specimens were measured, and one‐way ANOVA and Tukey–Kramer post hoc multiple comparisons tests were used to identify any statistical differences between groups. The addition of AgNPs has no effect on IS of PMMA. The incorporation of AgNPs affected the FS of PMMA depending on the concentration of nanoparticles. The addition of large‐sized nanoparticles to PMMA increases its FS. Accordingly, adding AgNP with proper concentrations to PMMA may enhance the mechanical properties of denture bases used in clinical practice. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45807.     

Uncertainty of pesticide residue concentration determined from ordinary and weighted linear regression curve

Determination of pesticide residues is based on calibration curves constructed for each batch of analysis. Calibration standard solutions are prepared from a known amount of reference material at different concentration levels covering the concentration range of the analyte in the analysed samples. In the scope of this study, the applicability of both ordinary linear and weighted linear regression (OLR and WLR) for pesticide residue analysis was investigated. We used 782 multipoint calibration curves obtained for 72 different analytical batches with high-pressure liquid chromatography equipped with an ultraviolet detector, and gas chromatography with electron capture, nitrogen phosphorus or mass spectrophotometer detectors. Quality criteria of the linear curves including regression coefficient, standard deviation of relative residuals and deviation of back calculated concentrations were calculated both for WLR and OLR methods. Moreover, the relative uncertainty of the predicted analyte concentration was estimated for both methods. It was concluded that calibration curve based on WLR complies with all the quality criteria set by international guidelines compared to those calculated with OLR. It means that all the data fit well with WLR for pesticide residue analysis. It was estimated that, regardless of the actual concentration range of the calibration, relative uncertainty at the lowest calibrated level ranged between 0.3% and 113.7% for OLR and between 0.2% and 22.1% for WLR. At or above 1/3 of the calibrated range, uncertainty of calibration curve ranged between 0.1% and 16.3% for OLR and 0% and 12.2% for WLR, and therefore, the two methods gave comparable results.     

The use of polyaniline films on flexible tape for supercapacitor applications

A sticky surface of a tape was adhered to a graphite surface and then the tape was peeled off. The insulator tape was coated with thin graphite and became conductive in order to use flexible tape as a current collector. Aniline was electrodeposited onto a flexible tape substrate having graphite layer by electrochemical polymerization method from an aqueous (H₂SO₄ solution containing aniline monomers) and non-aqueous media (a deep eutectic solvent containing aniline). The prepared polymeric electrodes were characterized by Fourier transform infrared spectroscopy, Raman, thermogravimetric analysis and scanning electron microscopy techniques. The electrochemical properties of coated and uncoated electrodes were also examined by cyclic voltammetry and galvanostatic charge discharge techniques. The polyaniline (PANI) coated tape can be used as a flexible electrode in supercapacitor applications because PANI coated electrodes are highly electroactive in Na₂SO₄ electrolyte. After 3000 cycles, the capacitance retention of PANI film electrodeposited from Ethaline bath was 90%, while the areal capacitance of PANI film obtained from acidic medium reaches 50% after 500 cycles. As PANI electrode is stable in an ionic liquid for long cycling, Ethaline ionic liquid can be used as electrolyte for PANI based supercapacitor electrode. PANI coated graphite on tape, which is prepared in an easy and inexpensive way is a promising flexible material for high performance supercapacitors.     

Influence of infrared final cooking on polycyclic aromatic hydrocarbon formation in ohmically pre-cooked beef meatballs

Effects of infrared cooking on polycyclic aromatic hydrocarbon (PAH) formation in ohmically pre-cooked beef meatballs were investigated. Samples were pre-cooked in a specially designed-continuous type ohmic cooking at a voltage gradient of 15.26 V/cm for 92 s. Infrared cooking was applied as a final cooking method at different combinations of heat fluxes (3.706, 5.678, 8.475 kW/m²), application distances (10.5, 13.5, 16.5 cm) and application durations (4, 8, 12 min). PAHs were analyzed by using high performance liquid chromatography (HPLC) equipped with a fluorescence detector. The total PAH levels were detected to be between 4.47 and 64 μg/kg. Benzo[a] pyrene (B[a]P) and PAH4 (sum of B[a]P, chrysene (Chr), benzo[a]anthracene (B[a]A) and benzo[b]fluoranthene (B[b]F)) levels detected in meatballs were below the EC limits. Ohmic pre-cooking followed by infrared cooking may be regarded as a safe cooking procedure of meatballs from a PAH contamination point of view.     

Enantioselective degradation of organochlorine pesticides in background soils: variability in field and laboratory studies

Variability in the enantioselective degradation of chiral organochlorine pesticides (alpha-HCH, cis- and trans-chlordane (CC and TC), and o,p'-DDT) in the field and laboratory was investigated. Background soils presumably receive the same EF signature of a compound via atmospheric deposition and then degrade that compound in a way that can vary over small spatial areas. Background soils from woodland and grassland areas were sampled to compare chiral signatures and determine the spatial variability within a few square meters. The enantiomer fractions, EF = areas of the (+)/[(+)+(-)]-enantiomers, showed variability between and within ecosystems. For example, the EF of CC varied between 0.272 -and 0.558 in nine samples taken over a few square meters, and a range of 0.431-0.506 was found within depths of a few centimeters. Woodland and grassland soils were spiked with alpha-HCH, TC, CC, and o,p'-DDT, and one portion was placed in the field to monitor changes in EF under in situ conditions and the other taken to the laboratory. In general, the enantiomer degradation preferences in the laboratory paralleled those in the field, with some differences. Soil organic matter content and pH exerted a minor influence on this variability. The results of this study have implications for the use of chiral compounds to make inferences about air-soil exchange and for the mechanisms of biodegradation/ biotransformation of anthropogenic compounds in soils.