DFT Study of Endohedral Atoms Effect on Electrophilicity of B16N16 Boron Nitride Nanocage: Comparative Analyses

Endohedral derivatives of B₁₆N₁₆ nanocage (M@B₁₆N₁₆, M?=?Li⁺, Na⁺, K⁺, Mg²⁺, Ne, O^2?, S^2?, F^?, Cl^?) and its iso-electronic fullerne M@C₃₂ have been employed to investigate the relation between the trapped atom/ion and electrophilicity of the B₁₆N₁₆ and C₃₂ nanocages. The electrophilicity index, ??, of these endohedral nanocages has been evaluated from the ionization potential and the electron affinity computed by vertical ionization/affinity at the B3LYP/6-311++G(df,pd) level. Obtained results illustrate that the nature of trapped atom/ion affects HOMO-LUMO band gap, global electrophilicity indices and reactivity of B₁₆N₁₆ and C₃₂ nanocages. Encapsulation B₁₆N₁₆ with different atom/ions may be a possible method for modifying HOMO-LUMO energy gap, electrophilicity and so chemical characteristics of and C₃₂ nanocages.     

An efficient and versatile synthesis of aromatic nitriles from aldehydes

A simple and direct method has been developed for synthesis of nitriles based on one-pot reaction of aromatic aldehydes with three different kind of reagents:CeCl₃7H₂O/KI/H₂O₂,CeCl₃·7H₂O/KI/UHP and（NH₄）₂Ce（NO₃）₆/KI/H₂O₂ in aqueous ammonia.     

Two New Phenylpropanoid Glycosides from the Leaves and Flowers of Erica arborea

Two new phenylpropanoid glucosides, 1,2‐erythro‐1‐(3,4,5‐trimethoxyphenyl)‐2‐(β‐D ‐glucopyranosyloxy)propan‐1,3‐diol ( 1 ) and 7,8‐threo‐2′,8‐epoxysyringylglycerol‐7‐O‐α‐D ‐glucopyranoside (ericarboside; 2 ) have been isolated together with four known compounds 2′,7‐epoxysyringylglycerol‐8‐O‐β‐D ‐glucopyranoside (ficuscarpanoside B; 3 ), benzylrutinoside (hydrangeifolin; 4 ), phenethylrutinoside ( 5 ), and caffeic acid from the BuOH soluble part of the MeOH extract of the leaves and flowers of E. arborea L. Final purification of the compounds was achieved on a reversed‐phase HPLC. Their structures have been elucidated by extensive 1D‐ and 2D‐NMR, and mass spectroscopic techniques.     

Magnetic polyvinylamine nanoparticles by in situ precipitation reaction

Magnetic nanoparticles represent emerging tools in biomedical and pharmaceutical research. Because in most cases, the surfaces of these nanoparticles are hydrophobic, surface modifiers are usually applied to stabilize the colloidal suspension in an aqueous media. This investigation reports a simple technique for the preparation of MnFe₂O₄ synthesized within polyvinylamine (PVAm) nanoparticle reactors. Magnetite nanoparticles were previously synthesized using a similar scheme; however, substituting MnFe₂O₄ for Fe₃O₄ improved nanoparticle magnetization properties and further established the synthetic approach. PVAm nanoparticles exhibited more than 18% manganese ferrite loading by weight, a saturation magnetization of ～ 40 emu/g of MnFe₂O₄, excellent colloidal stability, and reactive primary amines for possible drug conjugation or surface modification. Transmission electron micrographs revealed that the dispersions contained ～ 50 nm PVAm nanoparticles incorporating manganese ferrite particles with a size less than ～ 7 nm. This reaction scheme further justifies a unique synthetic methodology for magnetic nanoparticles offering potential use in contrast‐enhanced magnetic resonance imaging or drug delivery. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 991–996, 2010     

A Novel and Expedient Synthesis of 7‐Pyrimidinylpyrimido[4,5‐d]pyrimidinones

A novel and efficient procedure for the synthesis of new 7‐pyrimidinylpyrimido[4,5‐d]pyrimidinone derivatives was elaborated via the base‐promoted cyclodimerization reaction of 5‐[(dimethylamino)methylidene]‐6‐iminopyrimidine‐2,4(1H,3H)‐dione hydrochlorides. In an analogous manner, a 2‐thioxo analog was prepared starting with the corresponding 2‐thioxopyrimidin‐4‐one.     

Optimizing measurement uncertainty to reduce the risk and cost in the process of conformity assessment

Accreditation and Quality Assurance - Uncertainty in measurement is very important in the process of conformity assessment. As it is generally declared, based on the measured value of a property of...     

Kinetics and Mechanism Study of the Substitution Reactions of the Chloride Ligand in Dichloro(5,10,15,20)‐tetraphenyl‐21H,23H‐porphinato)tin(IV) by Organic Bases in Dimethylformamide Solvent

Substitution reactions of a Cl⁻ ligand in [SnCl₂(tpp)] (tpp=5,10,15,20‐tetraphenyl‐21H,23H‐porphinato(2−)) by five organic bases i.e., butylamine (BuNH₂), sec‐butylamine (^sBuNH₂), tert‐butylamine (^tBuNH₂), dibutylamine (Bu₂NH), and tributylamine (Bu₃N), as entering nucleophile in dimethylformamide at I=0.1M (NaNO₃) and 30–55° were studied. The second‐order rate constants for the substitution of a Cl⁻ ligand were found to be (36.86±1.14)⋅10⁻³, (32.91±0.79)⋅10⁻³, (22.21±0.58)⋅10⁻³, (19.09±0.66)⋅10⁻³, and (1.36±0.08)⋅10⁻³ M ⁻¹s⁻¹ at 40° for BuNH₂, ^tBuNH₂, ^sBuNH₂, Bu₂NH, and Bu₃N, respectively. In a temperature‐dependence study, the activation parameters ΔH^≠ and ΔS^≠ for the reaction of [SnCl₂(tpp)] with the organic bases were determined as 38.61±4.79 kJ mol⁻¹ and −150.40±15.46 J K⁻¹mol⁻¹ for BuNH₂, 40.95±4.79 kJ mol⁻¹ and −143.75±15.46 J K⁻¹mol⁻¹ for ^tBuNH₂, 30.88±2.43 kJ mol⁻¹ and −179.00±7.82 J K⁻¹mol⁻¹ for ^sBuNH₂, 26.56±2.97 kJ mol⁻¹ and −194.05±9.39 J K⁻¹mol⁻¹ for Bu₂NH, and 39.37±2.25 kJ mol⁻¹ and −174.68±7.07 J K⁻¹ mol⁻¹ for Bu₃N. From the linear rate dependence on the concentration of the bases, the span of k₂ values, and the large negative values of the activation entropy, an associative (A) mechanism is deduced for the ligand substitution.     

Empirical Hankel transforms and its applications to goodness-of-fit tests

We introduce a special Hankel transform for probability distributions on the nonnegative half-line and discuss some of its properties. Due to the uniqueness of the transform we suggest an integral type test statistic based on the empirical Hankel transform to treat simple and composite hypotheses goodness-of-fit problems. The special case of exponential distributions is studied in detail.     

A new multiobjective procedure for solving nonconvex environmental/economic power dispatch

In this article, an improved multiobjective chaotic interactive honey bee mating optimization (CIHBMO) is proposed to find the feasible optimal solution of the environmental/economic power dispatch problem with considering operational constraints of the generators. The three conflicting and noncommensurable: fuel cost, pollutant emissions, and system loss, should be minimized simultaneously while satisfying certain system constraints. To achieve a good design with different solutions in a multiobjective optimization problem, Pareto dominance concept is used to generate and sort the dominated and nondominated solutions. Also, fuzzy set theory is used to extract the best compromise solution. The propose method has been individually examined and applied to the standard Institute of Electrical and Electronics Engineers (IEEE) 30‐bus six generator, IEEE 180‐bus 14 generator and 40 generating unit (with valve point effect) test systems. The computational results reveal that the multiobjective CIHBMO algorithm has excellent convergence characteristics and is superior to other multiobjective optimization algorithms. Also, the result shows its great potential in handling the multiobjective problems in power systems. © 2014 Wiley Periodicals, Inc. Complexity 20: 47–62, 2014