Photo-oxidation of 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones

A variety of Biginelli 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones are efficiently oxidized to their corresponding pyrimidin-2(1H)-one derivatives upon UV irradiation under argon atmosphere in chloroform solution. The nature of the additional substituent on the phenyl ring located on C-4 of the heterocyclic ring influences the rate of reaction. An electron-transfer induced photoreaction is proposed based on the formation of HCl and CH₂Cl₂.     

Estimation of thermal conductivity of ethylene glycol-based nanofluid with hybrid suspensions of SWCNT–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanoparticles by correlation and ANN methods using experimental data

In the present paper, the effects of temperature and volume fraction on thermal conductivity of SWCNT–Al₂O₃/EG hybrid nanofluid are investigated. Single-walled carbon nanotube with outer diameter of 1–2 nm and aluminum oxide nanoparticles with mean diameter of 20 nm with the ratio of 30 and 70%, respectively, were dispersed in the base fluid. The measurements were conducted on samples with volume fractions of 0.04, 0.08, 0.15, 0.3, 0.5, 0.8, 1.5 and 2.5. In order to investigate the effects of temperature on thermal conductivity of the nanofluid, this characteristic was measured in five different temperatures of 30, 35, 40, 45 and 50 °C. The results indicate that enhancement of nanoparticles’ thickness in low volume fractions and at any temperature causes a considerable increment in thermal conductivity of the nanofluid. In this study, the highest enhancement of thermal conductivity was 41.2% which was achieved at the temperature of 50 °C and volume fraction of 2.5%. Based on the experimental data, an experimental correlation and a neural network are presented and for thermal conductivity of the nanofluid in terms of volume fraction and temperature. Comparing outputs of the experimental correlation and the designed artificial neural network with experimental data, the maximum error values for the experimental correlation and the artificial neural network were, respectively, 2.6 and 1.94% which indicate the excellent accuracy of both methods in prediction of thermal conductivity.     

TM waves in cylindrical superlattices (LANS) bounded by left-handed material (LHM)

The investigation of TM wave propagation inside a cylindrical waveguide composed of antiferromagnetic/nonmagnetic superlattices (LANS), bounded by left-handed material (LHM), is presented. We have derived the eigenmode equation and obtained the solutions for TM propagation modes. We found that the waveguide supports backward TM waves since both electric permittivity and magnetic permeability of the LHM are negative. We also illustrated the dependence of the wave index n _x on the magnetic fraction f ₁ and the reduced radius of the LANS. The largest propagation lengths of TM waves and the best confinement are achieved for the thinnest LANS of less magnetic material. Moreover, we displayed the influence of the magnetic permeability μ _h and the electric permittivity ε _h of the LHM on the power flow of TM waves. Larger wave indices have been switched by increasing μ _h and ε _h .     

A phosphorimetric investigation of the external heavy-atom effect in aqueous solution and its correlation with phosphorescence intensity and quantum yield

Excitation and emission phosphorescence spectra, lifetimes, and relative quantum yields of benzene and ten monosubstituted benzenes were determined at 77 K in methanol/water 10/90 v/v and in sodium iodide/methanol/water solutions. Substituents CHO, COCH(3), COC(2)H(5), OH, OCH(3), H(3), C(2)H(5), CH(2)OH and N(CH(3))(2) were investigated. Aqueous sodium iodide solutions were found to be a suitable heavy-atom solvent for phosophorimetry. Heavy-atom enhancement factors ranged from 1.2 to 8.3 according to the molecular structure and a marked decrease of the lifetime was observed for nine compounds in aqueous sodium iodide solution. A linear log-log correlation was obtained between the relative corrected phosphorescence signal and the heavy-atom enhancement factor of the monosubstituted benzenes. A similar correlation was found between the quantum yields and the heavy-atom enhancement factors. The analytical usefulness of these correlations is evident for the prediction of the magnitude of the heavy-atom effect.     

TheK-conversion coefficient of the 321 keVE1 transition in Hf177

TheK-conversion coefficient of the 321 keVE1 transition in Hf¹⁷⁷ has been measured by means of an iron free double focusing beta-ray spectrometer, using the internalexternal conversion method. The result obtained for α _K (321)=0.162±0.016 is in disagreement with the theoretical values for pureE1 transition (α _K =0.0154) calculated bySliv andBand. The large anomaly observed in theK-conversion process of the inhibitedE1 transition is compatible with a largeM2 admixture or, more probable with the presence of penetration matrix elements.     

Mixed thioalkyl-azoimine (SNN′)/α-diimine–ruthenium complexes: synthesis,characterization, DFT calculations,crystal structure and application as pre-catalysts for hydrogenation of acetophenone

Transition Metal Chemistry - Eight ruthenium complexes having thioalkyl-azoimine (SNN) ligands of two general types have been synthesized: (a) [Ru(L)(bipy)Cl](PF6) where {bipy = bipyridine,...     

Determination of gold in water samples using electromembrane extraction

In this work, an electromembrane extraction (EME) technique was used for the extraction and determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5?µg L^?1 (S/N?=?3) on the optimized variables. The intra- and interday precisions (%) were found to be 6.7% and 2.6%, respectively. This technique was then applied for analysis of gold from environment water samples.     

Dimethylformamide dimethyl acetal in heterocyclic synthesis: Synthesis of polyfunctionally substituted pyridine derivatives as precursors to bicycles and polycycles

Polysubstituted pyridines 11a,c and 12 were prepared by the reaction of benzoylacetone with dimethylformamide dimethyl acetal followed by treatment with cyanothioacetamide 9a , cyanoacetamide 9b and the anion of malononitrile dimmer 9c in dry DMF. When the reaction was carried out in ethanol as a solvent and piperidine as a base afforded 14a,b . Thienopyridines 16a,b were prepared by the reaction of pyridinethiones 11a and 14a with 2‐chloro‐N‐p‐tolyl‐acetamide ( 15 ). Further reaction of thienopyridines 16a,b with either DMFDMA or nitrous acid to gave 17a,b and 18a,b respectively. The reaction of pyridine derivative 11c with hydrazine and phenylhydrazine afforded the tricyclic compounds 19a,b .     

The Multifaceted Role of Curcumin in Advanced Nanocurcumin Form in the Treatment and Management of Chronic Disorders

Curcumin is the primary polyphenol in turmeric’s curcuminoid class. It has a wide range of therapeutic applications, such as anti-inflammatory, antioxidant, antidiabetic, hepatoprotective, antibacterial, and anticancer effects against various cancers, but has poor solubility and low bioavailability. Objective: To improve curcumin’s bioavailability, plasma concentration, and cellular permeability processes. The nanocurcumin approach over curcumin has been proven appropriate for encapsulating or loading curcumin (nanocurcumin) to increase its therapeutic potential. Conclusion: Though incorporating curcumin into nanocurcumin form may be a viable method for overcoming its intrinsic limitations, and there are reasonable concerns regarding its toxicological safety once it enters biological pathways. This review article mainly highlights the therapeutic benefits of nanocurcumin over curcumin.