Metallic stripe in two dimensions: stability and spin-charge separation

The problems of charge stripe formation, spin-charge separation, and stability of the antiphase domain wall (ADW) associated with a stripe are addressed using an analytical approach to the t- J(z) model. We show that a metallic stripe together with its ADW is the ground state of the problem in the low doping regime. The stripe is described as a system of spinons and magnetically confined holons strongly coupled to the two dimensional spin environment with holon-spin-polaron elementary excitations filling a one-dimensional band.     

Chelate‐Thiolate‐Coordinate Ligands Modulating the Configuration and Electrochemical Property of Dinitrosyliron Complexes (DNICs)

As opposed to the reversible redox reaction ({Fe(NO)₂}¹⁰ reduced‐form DNIC [(NO)₂Fe(S(CH₂)₃S)]^2? ( 1 )?{Fe(NO)₂}⁹ oxidized‐form [(NO)₂Fe(S(CH₂)₃S)]^?), the chemical oxidation of the {Fe(NO)₂}¹⁰ DNIC [(NO)₂Fe(S(CH₂)₂S)]^2? ( 2 ) generates the dinuclear {Fe(NO)₂}⁹–{Fe(NO)₂}⁹ complex [(NO)₂Fe(μ‐SC₂H₄S)₂Fe(NO)₂]^2? ( 3 ) bridged by two terminal [SC₂H₄S]^2? ligands. On the basis of the Fe K‐edge pre‐edge energy and S K‐edge XAS, the oxidation of complex 1 yielding [(NO)₂Fe(S(CH₂)₃S)]^? is predominantly a metal‐based oxidation. The smaller S1‐Fe1‐S2 bond angle of 94.1(1)° observed in complex 1 (S1‐Fe1‐S2 88.6(1)° in complex 2 ), compared to the bigger bond angle of 100.9(1)° in the {Fe(NO)₂}⁹ DNIC [(NO)₂Fe(S(CH₂)₃S)]^?, may be ascribed to the electron‐rich {Fe(NO)₂}¹⁰ DNIC preferring a restricted bite angle to alleviate the electronic donation of the chelating thiolate to the electron‐rich {Fe(NO)₂}¹⁰ core. The extended transition state and natural orbitals for chemical valence (ETS‐NOCV) analysis on the edt‐/pdt‐chelated {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ DNICs demonstrates how two key bonding interactions, that is, a Fe?S covalent σ bond and thiolate to the Fe d charge donation, between the chelating thiolate ligand and the {Fe(NO)₂}^9/10 core could be modulated by the backbone lengths of the chelating thiolate ligands to tune the electrochemical redox potential (E_1/2=?1.64 V for complex 1 and E_1/2=?1.33 V for complex 2 ) and to dictate structural rearrangement/chemical transformations (S‐Fe‐S bite angle and monomeric vs. dimeric DNICs).     

Orientation-induced crystallization in isotactic polypropylene melt by shear deformation

Development of orientation-induced precursor structures (nuclei) prior to crystallization in isotactic polypropylene melt under shear flow was studied by in-situ synchrotron small-angle X-ray scattering (SAXS) and rheo-optical techniques. SAXS patterns at 165°C immediately after shear (rate = 60 s⁻¹, t_s = 5 s) showed emergence of equatorial streaks due to oriented structures (microfibrils or shish) parallel to the flow direction and of meridional maxima due to growth of the oriented layer-like structures (kebabs) perpendicular to the flow. SAXS patterns at later times (t = 60 min after shear) indicated that the induced oriented structures were stable above the nominal melting point of iPP. DSC thermograms of sheared iPP samples confirmed the presence of two populations of crystalline fractions; one at 164°C (corresponding to the normal melting point) and the other at 179°C (corresponding to melting of oriented crystalline structures). Time-resolved optical micrography of sheared iPP melt (rate = 10 s⁻¹, t_s = 60 s, T = 148°C) provided further information on orientation-induced morphology at the microscopic scale. The optical micrographs showed growth of highly elongated micron size fibril structures (threads) immediately after shear and additional spherulities nucleated on the fibrils at the later stages. Results from SAXS and rheo-optical studies suggest that a stable scaffold (network) of nuclei, consisting of shear-induced microfibrillar structures along the flow direction superimposed by layered structures perpendicular to the flow direction, form in polymer melt prior to the occurance of primary crystallization. The scaffold dictates the final morphological features in polymer.     

Synthesis, characterization and catalytic activity of lithium and sodium iminophenoxide complexes towards ring-opening polymerization of L-lactide

A series of lithium and sodium iminophenoxide complexes have been successfully synthesized and characterized by X-ray crystallography and investigated as catalysts for the ring opening polymerization of L-lactide. The nature and steric bulk of the ligands coordinated to the central metal ions greatly influence the catalytic properties. Complexes with bidenate ligands exhibit higher catalytic activity than tridentate counterparts because the third coordination atom contends with L-lactide, which decreases activity. Oxygen is the third atom in the tridentate ligand, providing stronger chelation ability with Li and Na than nitrogen or sulfur and occupies the space with which L-lactide is coordinated.     

Flexible generation of optical beams with quasicrystalline structures via astigmatism induced by a tilted lens

We theoretically show that a family of optical beams with vortex-lattice structures can be reliably generated by tilting the focal lens to introduce the relative phases between the interfering beams. We also experimentally generate the quasicrystal beams to confirm the theoretical analysis. With the analytical wave functions and experimental patterns, a variety of vortex-lattice structures are manifested.     

Evolutionary Pareto optimizers for continuous review stochastic inventory systems

Multi-objective inventory control has been studied for a long time. The trade-off analysis of cycle stock investment and workload, so called the exchange curve concept, possibly dates back to several decades ago. A classical way to such trade-off analysis is to utilize the Lagrangian relaxation technique or interactive method to search for the optimum in a sequence of single objective optimization problems. However, the field of optimization has been changed over the last few decades since the concept of evolutionary computation was introduced. In this paper, a continuous review stochastic inventory system with three objectives about cost and shortage is resolved by evolutionary computation in order to plan for the control policies under backordering and lost sales. Two evolutionary optimizers, multi-objective electromagnetism-like optimization (MOEMO) and multi-objective particle swarm optimization (MOPSO), are employed to well and fast approximate the non-dominated policies in term of lot size and safety stock. Trade-offs are observed in a non-dominated set that no one excels the others in all objectives. Computational results show that the evolutionary Pareto optimizers could generate trade-off solutions potentially ignored by the well-known simultaneous method. Comparisons between the results of backordering and lost sales indicate that decision makers will make more deliberate choices about lot sizing and safety stocking when unsatisfied demand is completely lost.     

Chiral amplification in one-dimensional helical nanostructures self-organized from phenylethynyl thiophene with elaborated long-chain dicarboxamides

A bis-phenylethynyl thiophene derivative functionalized with long-chain pyridyl biscarboxamides displayed unique helical morphology in the xerogel form via nicely complementary intermolecular interactions. The helical nanostructures visualized by TEM and AFM remarkably matched well with the computational results. Supramolecular chirality can be amplified by coassembly of a chiral conductor to bias the helical arrangement.     

Economic order quantity model and Taguchi’s cost of poor quality

In this paper we consider defective products and Taguchi’s cost of poor quality in the economic order quantity (EOQ) model. We assume that the product quality performs a normal distribution function, and the Taguchi’s poor quality cost has been involved. From our analysis, it has been found that the annual profit will be decreased if the poor quality of product and Taguchi’s quality cost are involved in the model. It has also been found that economic order quantity in our model is larger than that in a traditional EOQ model.     

Structural Diversity in the Self‐assembly of Cd(II) Complexes Containing 2,6‐Dimethyl‐3,5‐dicyano‐4‐(4‐pyridyl)‐1,4‐dihydropyridine

The syntheses, structures and properties of the complexes [CdBr₂( L )₂·4H₂O]_n [ L = 2,6‐dimethyl‐3,5‐dicyano‐4‐(4‐pyridyl)‐1,4‐dihydropyridine], 1 and [Cd(SCN)₂( L )₂(H₂O)]_n, 2 , are reported. In polymeric complexes 1 — 2 , the L ligands bridge the metal centers through the pyrimidyl and cyano nitrogen atoms forming 1‐D double‐stranded chain and zigzag chain, respectively. The L ligands in complex 1 act as κ1, κ1‐bidentate bridging ligand, whereas the L ligands in complex 2 act as κ1‐monodentae and κ1, κ1‐bidentate bridging ligand. The molecules of these complexes are interlinked through various weak interactions that form the packed structure. All the complexes exhibit emissions which may be tentatively assigned as intraligand (IL) π→π* transitions.