Optimality via generalized approximate convexity and quasiefficiency

In this article, we look beyond convexity and introduce the four new classes of functions, namely, approximate pseudoconvex functions of type I and type II and approximate quasiconvex functions of type I and type II. Suitable examples illustrating the non emptiness of the newly defined classes and distinguishing them from the existing classical notions of pseudoconvexity and quasiconvexity are provided. These newly defined concepts are then employed to establish sufficient optimality conditions for the quasi efficient solutions of a vector optimization problem.     

Complex magnetic ordering as a driving mechanism of multifunctional properties of Heusler alloys from first principles

First-principles calculations are used to study the structural, electronic and magnetic properties of (Pd, Pt)-Mn-Ni-(Ga, In, Sn, Sb) alloys, which display multifunctional properties like the magnetic shape-memory, magnetocaloric and exchange bias effect. The ab initio calculations give a basic understanding of the underlying physics which is associated with the complex magnetic behavior arising from competing ferro- and antiferromagnetic interactions with increasing number of Mn excess atoms in the unit cell. This information allows to optimize, for example, the magnetocaloric effect by using the strong influence of compositional changes on the magnetic interactions. Thermodynamic properties can be calculated by using the ab initio magnetic exchange parameters in finite-temperature Monte Carlo simulations. We present guidelines of how to improve the functional properties. For Pt-Ni-Mn-Ga alloys, a shape memory effect with 14% strain can be achieved in an external magnetic field.     

A convenient route to 1,3-diynes using ligand-free Cadiot–Chodkiewicz coupling reaction at room temperature under aerobic conditions

In this study, we report a copper-catalyzed ligand-free Cadiot–Chodkiewicz coupling reaction. No additives or ligands are required for this Cu-catalyzed C(sp)–C(sp) coupling reaction of terminal alkynes with alkynyl halides. The low cost of copper catalyst, excellent yield of the products, suppression of side-products and mild reaction conditions are the major advantages of this protocol.     

Chemical constituents from the flowers of Satsuma mandarin and their free radical scavenging and α-glucosidase inhibitory activities

Flowers of Citrus plants are used as mild sedatives and for the treatment of insomnia in traditional medicines. In Japan, tea made from the flowers of Satsuma mandarin is consumed as healthy drink. Hesperidin (1), hesperetin (2), rutin (3), quercetin (4), nicotiflorin (5), eriocitrin (6), narirutin (7), phenylethyl glucoside (8) and unshuoside A (9) were isolated from the MeOH extract of fresh flowers. Structure elucidation of these compounds was performed on the basis of NMR spectroscopic data. Among them, rutin (3), quercetin (4) and eriocitrin (6) showed potent free radical scavenging activity, whereas hesperetin (2) and quercetin (4) showed potent α-glucosidase inhibitory activity.     

Conformationally Locked Cyclo[2]Dipyrrins Linked with Anthracene Subunits: Synthesis and Chiroptical Properties

Herein, we report the synthesis of anthracene-containing twisted cyclo[2]dipyrrin 1 by utilizing a non-planar building block, 1,5-dipyrrylanthracene (1,5-DPA). The non-planar nature of the macrocycle enhanced the solubility and helped in structural characterization. Macrocycle 1 adopts a twisted ‘figure of eight’ conformation stabilized by strong intramolecular H-bonding interactions and exists as a pair of helical enantiomers, as revealed by X-ray crystallographic analysis. More importantly, the sterically locked structure enabled facile optical resolution using chiral HPLC. The (P,P) and (M,M) enantiomers show moderate chiroptical properties, such as absorption dissymmetry factors |g_abs| in the order of 10⁻³, and luminescence dissymmetry factors |g_lum| of 3.8×10⁻³ and 2.9×10⁻³ at 702 nm, respectively.     

WKB and MAF quantization rules for spatially confined quantum mechanical systems

A formalism is developed to obtain the energy eigenvalues of spatially confined quantum mechanical systems in the framework of the usual Wentzel–Kramers–Brillouin (WKB) and modified airy function (MAF) methods. To illustrate the working rule, the techniques are applied to three different cases, viz. the confined one‐dimensional harmonic and quartic oscillators and a boxed‐in charged particle subject to an external electric field. The energies thus obtained are compared with those from shifted 1/N expansion, variational, and other methods, as well as the available exact numerical results. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 497–504, 1999     

Bis(2‐but­yl‐N,N′‐diisopropyl­amidinato)dichloro­hafnium(IV)

The title compound, [Hf(C₁₁H₂₃N₂)₂Cl₂], is a monomeric hafnium(IV) complex containing two bidentate amidinate ligands and two cis Cl atoms. The crystals are triclinic (space group ) and there is one independent six‐coordinate monomer with a highly distorted octa­hedral geometry in the asymmetric unit. The reported structure is the first hafnium–amidinate complex to be characterized successfully by single‐crystal X‐ray diffraction.     

Photoelectrochemical performance of bilayered Fe–TiO<Subscript>2</Subscript>/Zn–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> thin films for solar generation of hydrogen

A visible-light sensitive bilayered photoanode of Fe–TiO₂/Zn–Fe₂O₃ has been developed by spray pyrolytically depositing Zn–Fe₂O₃ layers onto predeposited Fe–TiO₂ thin film on ITO substrate. Fe–TiO₂/Zn–Fe₂O₃ photoelectrodes were characterized by XRD, Raman, AFM, UV-vis absorption spectroscopy. Photoelectrochemical properties of bilayered Fe–TiO₂/Zn–Fe₂O₃ photoelectrode were studied by Mott–Schottky curves and I–V characteristics. Bilayered Fe–TiO₂/Zn–Fe₂O₃ photoelectrode was observed to possess much higher separation efficiency of photogenerated charge carriers and could generate nine times better photocurrent density than pure Fe–TiO₂. Solar to hydrogen conversion efficiency exhibited by this electrode was 0.77%.     

β-Fe2O3 nanomaterials from an iron(II) diketonate-diamine complex: a study from molecular precursor to growth process

Iron oxide is a key multi-functional material in many different fields of modern technology. The β-Fe(2)O(3) cubic phase, one of the least studied Fe-O systems, was obtained by Chemical Vapor Deposition (CVD) using for the first time a Fe(II) β-diketonate diamine complex, Fe(hfa)(2)·TMEDA, as the molecular source (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N',N'-tetramethylethylenediamine). The strong visible light absorption of β-Fe(2)O(3) deposits highlights their possible functional application in photocatalytic hydrogen production under solar light. A comprehensive investigation on the Fe(ii) complex, performed by a joint experimental-theoretical approach, explains the molecular origin of its excellent thermal behaviour and reveals why this species is a successful precursor for the CVD of iron oxide nanostructures.     

Aqueous Synthesis of Triphenylphosphine-Modified Gold Nanoparticles for Synergistic In Vitro and In Vivo Photothermal Chemotherapy

Triphenylphosphine (TPP) surface-functionalized and F-108 Pluronic-stabilized gold nanoparticles (F-108@TPP-AuNPs) have been synthesized through a one-step approach, leading to well-defined (9.6±1.6 nm) and water-soluble nanoparticles by microwave heating an aqueous solution of TPP-Au^ICl in the presence of a Pluronic polymer under basic conditions. TPP release was negligible under physiological conditions, but enhanced significantly at an acidic pH (5.4) mimicking that of a cancer cell. Laser irradiation (532 nm) raised the temperature of an aqueous solution of F-108@TPP-AuNPs to 51.7 °C within 5 min, confirming efficient light-to-heat conversion capabilities without significant photodegradation. TEM confirmed intracellular localization of F-108@TPP-AuNPs in the cytosol, endosomes and lysosomes of HeLa cells. F-108@TPP-AuNPs were well tolerated by HeLa cells and zebrafish embryos at ambient temperatures and became toxic upon heat activation, suggesting synergistic interactions between heat and cytotoxic action by TPP.