Solid-phase extraction based on multi-walled carbon nanotube (MWCNT) sorbents combined with bio-coacervation extraction for the determination of atrazine from water samples followed by HPLC analysis

In this study, combined technique of solid-phase extraction based on multi-walled carbon nanotubes with bio-coacervation extraction (SPE-MWCNT-BCAE) has been developed as a new sample preparation method for the determination of atrazine from water samples. The proposed method involves two steps: analyte enrichment on the solid sorbent and subsequently elution of the analyte by an appropriate solvent. Multi-walled carbon nanotubes (MWCNTs) were used as the sorbent. They have high specific surface area, nano-scale structure and high diffusion rate. The second step is based on the use of bioaggregates for analyte re-enrichment, which consists of biosurfactants and ionic liquid. This method follows the principles of green chemistry. Parameters affecting the extraction efficiency were optimized. Under optimum conditions, the enrichment factor was 176. The linear dynamic range (LDR) and limit of detection (LOD) were 2–100 µg L^?1 and 0.66 µg L^?1, respectively. The relative standard deviation (RSD) for six replicate measurements was 3.8%. The method was applied to the determination of ultratrace levels of atrazine in environmental water samples with satisfactory results.     

Development of novel magnetic solid-phase extraction sorbent based on Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/carbon nanosphere/polypyrrole composite and their application to the enrichment of polycyclic aromatic hydrocarbons from water samples prior to GC–FID analysis

We describe a magnetic nanocomposite that consists of Fe₃O₄/carbon nanosphere/polypyrrole (Fe₃O₄/CNS/PPy). The synthesized nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The nanocomposite was successfully applied to extract of the polycyclic aromatic hydrocarbons (PAHs) from water samples. Compared to Fe₃O₄/PPy, the Fe₃O₄/CNS/PPy nanocomposite exhibits improved properties in terms of extraction. The amount of adsorbent, salt effect, extraction time, desorption time, type, and the volume of desorption solvent were optimized. Following the desorption of the extracted analytes, the PAHs (i.e., naphthalene, 2-methylnaphthalene, 2-bromonaphthalene, fluorene, and anthracene) were quantified by gas chromatography–flame ionization detector. The PAHs can be determined in 0.05–100.00 ng mL^?1 concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.01 to 0.05 ng mL^?1. The repeatability of the method was investigated with relative standard deviations of lower than 9.9% (n = 5). Also, the recoveries from spiked real water samples were in the range of 88.9–99.0%. The results indicate that the novel material can be successfully applied for the extraction and analysis of PAHs from water samples.     

The use of Cr (CO)6 as an alternative CO source in Pd‐catalyzed C‐N bond formation: Synthesis of benzamides

An efficient strategy for the synthesis of benzamides from acetamides and aryl iodides using 1 mol% Pd (OAc)₂ as catalyst and Cr (CO)₆ as CO‐precursor is described. This new synthetic methodology displays high functional group tolerance on both substrates and avoids the need for ligands, reducing agents, or other additives. The corresponding products were obtained in good to excellent yields at atmospheric pressure under mild reaction conditions.     

Enhanced properties of photovoltaic devices tailored with novel supramolecular structures based on reduced graphene oxide nanosheets grafted/functionalized with thiophenic materials

For verifying the influence of donor–acceptor supramolecules on photovoltaic properties, different hybrids were designed and used in organic solar cells. In this respect, reduced graphene oxide (rGO) was functionalization with 2‐thiophene acetic acid (rGO‐f‐TAA) and grafted with poly(3‐dodecylthiophene) (rGO‐g‐PDDT) and poly(3‐thiophene ethanol) (rGO‐g‐PTEt) to manipulate orientation of poly(3‐hexylthiophene) (P3HT) assemblies. Face‐on, edge‐on, and flat‐on orientations were detected for assembled P3HTs on rGO and its functionalized and grafted derivatives, respectively. Alteration of P3HT orientation from face‐on to flat‐on enhanced current density (J _sc), fill factor (FF), and power conversion efficiency (PCE) and thus J _sc = 7.11 mA cm^?2, FF = 47%, and PCE = 2.14% were acquired. By adding phenyl‐C71‐butyric acid methyl ester (PC71BM) to active layers composed of pre‐designed P3HT/rGO, P3HT/rGO‐f‐TAA, P3HT/rGO‐g‐PDDT, and P3HT/rGO‐g‐PTEt hybrids, photovoltaic characteristics further improved, demonstrating that supramolecules appropriately mediated in P3HT:PC71BM solar cells. Phase separation was more intensified in best‐performing photovoltaic systems. Larger P3HT crystals assembled onto grafted rGOs (95–143 nm) may have acted as convenient templates for the larger and more intensified phase separation in P3HT:PCBM films. The best performances were reached for P3HT:P3HT/rGO‐g‐PDDT:PCBM (J _sc = 9.45 mA cm^?2, FF = 54%, and PCE = 3.16%) and P3HT:P3HT/rGO‐g‐PTEt:PCBM (J _sc = 9.32 mA cm^?2, FF = 53%, and PCE = 3.11%) photovoltaic systems. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1877–1889     

Photophysical and optoelectronic properties of a platinum(II) complex and its derivatives,designed as a highly efficient OLED emitter: A theoretical study

New platinum(II) complex with picolinate (pic) and 2-phenyl naphtothiazole (pntl) ligand as the guest material has been designed and its capability for OLED applications have been examined. Also, we have studied the effects of different substitutions (ie, electron-withdrawing and electron donating groups) on naphtothiazole moiety on optovoltaic characters. We have employed density functional theoretical (B3LYP/DFT) methods to reveal the photophysical and structure properties relationships with the typical host material. The valence MO energies, vertical and adiabatic triplet energy, reorganization energy, and triplet exciton generation fraction (χ _T) have been extensively studied to exploring high phosphorescence efficiency in OLEDs. It has been predicted that substituted systems are good candidates for OLED applications as well as their parent system.     

Enlargements of the Moreau–Rockafellar Subdifferential

Set-Valued and Variational Analysis - This paper proposes three enlargements of the conventional Moreau–Rockafellar subdifferential: the sup-, sup?- and symmetric subdifferentials. They...     

Electrospun metal‐organic framework/polyacrylonitrile composite nanofibrous mat as a microsorbent for the extraction of tetracycline residue in human blood plasma

A new composite nanofiber of polyacrylonitrile doped with copper benzene‐1,3,5‐tricarboxylate metal‐organic framework was fabricated by electrospinning and used as a microsorbent in the solid‐phase extraction of trace tetracycline. The chemical structure of the adsorbent was studied by X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area analysis, and Barrett‐Joyner‐Halenda pore size and volume analysis techniques. The significant parameters of the method including desorption solvent kind and volume, adsorbent mass, pH, and salt percentage were investigated. At the optimized conditions, the linear range was 8–1000 μg/L with a determination coefficient (R²) of 0.9954. The limits of detection and quantification were 2.40 and 8.00 μg/L, respectively. The inter‐ and intraday precisions were 4.7 and 3.4%, respectively. The developed extraction method was followed by high‐performance liquid chromatography and applied for the determination of tetracycline in human blood plasma, and good relative recoveries (97.3‐104.5%) were obtained.     

Effect of Partially Hydrolyzed Kappa-Casein on Physicochemical and Sensory Properties of Heated Milk

The chemical, physical, and sensory characteristics of renneted skim milk (RSM) containing partially hydrolyzed κ-casein were assessed and compared with skim milk (control). Rennet was added to heated milk (60°C for 15 minutes) at seven concentrations from 0.1 to 0.7 mL rennet/100 mL milk followed by heating to 63°C for 30 minutes in order to inactivate the rennet. The RSM samples had higher viscosity as well as whiter, yellower, and greener color in comparison with control sample. The range of size distribution of casein aggregates was larger than that of skim milk, while being within the range of fat mimetics.     

Biofabrication of iron oxide nanoparticles by leaf extract of Rhamnus virgata: Characterization and evaluation of cytotoxic,antimicrobial and antioxidant potentials

In the present study, plant‐mediated synthesis of iron oxide nanoparticles (IONPs) using leaves extract of Rhamnus virgata (Roxb.) as a potential stabilizing, reducing and chelating agent is reported. The biogenic IONPs are extensively characterized for their physical and biological properties. The morphology, structure and physicochemical properties of biogenic IONPs were characterized using ultraviolet spectroscopy, X‐ray diffraction, Fourier transform‐infrared analysis, scanning electron microscopy, energy‐dispersive spectroscopy, transmission electron microscopy, Raman spectroscopy and dynamic light scattering. The Scherrer equation deduced a mean crystallite size of ~20 nm for IONPs. Detailed in vitro biological activities revealed significant therapeutic potentials for IONPs. Potential antibacterial and antifungal activities are reported for IONPs. Bioinspired IONPs have shown potential results against HepG2 cells (IC₅₀: 13.47 μg/ml). Dose‐dependent cytotoxicity assays were revealed against Leishmania tropica (KMH₂₃) promastigotes (IC₅₀: 8.08 μg/ml) and amastigotes (IC₅₀: 20.82 μg/ml) using different concentrations of IONPs (1–200 μg/ml). The cytotoxic activity was also studied using brine shrimps, and their IC₅₀ value was calculated as 32.41 μg/ml. Significant antioxidant [TAC (51.4%), DPPH (79.4%) and total reducing power (62%)], protein kinase and alpha amylase inhibition assays were revealed. The biocompatibility assays using red blood cells (> 200 μg/ml) and macrophages (> 200 μg/ml) confirmed the biosafe nature of IONPs. In conclusion, bioinspired IONPs have shown potential biological applications and should be subjected to further research work to develop their nano‐pharmacological relevance in biomedical applications.     

Highly Selective and Sensitive Benzimidazole Based Bifunctional Sensor for Targeting Inedible Azo Dyes in Red Chilli,Red Food Color,Turmeric Powder,and Cu(Ii) in Coconut Water

In this study, a simple Benzimidazole based bifunctional chemosensor 4-(2-(3,4-dimethoxyphenyl)-1H-benzo[d]imidazol-6-yl) benzene-1,2-diamine, L was synthesized and characterized. The sensor proved to be selective and sensitive towards detecting banned azo dyes Sudan Dye I, II, and Metanil Yellow via fluorescence turn-off response. The proposed mechanism of fluorescence quenching was the inner filter effect. LODs for Sudan I, II, and Metanil Yellow were found to be 0.009 µM, 0.012 µM, and 0.0073 µM, respectively. The developed chemosensor also showed a colorimetric response towards Cu (II) ions via an apparent color change from yellow to pink. LOD for Cu (II) ions was found to be 1.2 µM. The synthesized benzimidazole based bifunctional chemosensor was adequately tested to determine Sudan I in Red chili powder and red Food color samples, Metanil yellow in turmeric powder, and Cu(II) packaged coconut water.