Decentralization versus coordination in competing supply chains under retailers’ extended warranties

This paper studies a two-tier duopoly competing supply chain system consisting of two manufacturers and two exclusive retailers. Both manufacturers produce differentiated products and both retailers provide extended warranties for the products they sell. Two types of channel-structure strategy options are considered: a decentralized structure with a wholesale price contract and a coordinated structure with a sophisticated contract. We first derive the equilibrium outcomes under three possible chain-to-chain competition scenarios. Subsequently, we reveal how manufacturers control their retail channels to gain more supply chain system profit under an interactive environment with supply chain competition and retailers’ extended warranties. We find that pure coordinated channel competition and pure decentralized channel competition may both reach equilibrium. Furthermore, the interaction forces of supply chain competition and extended warranty service significantly impact the characteristics of the equilibria. Finally, we analyze the competing supply chain’s coordination contract design by using the example of a two-part tariff contract, and determine the feasible contract parameter range that results in a win-win solution for supply chain members.

     

Facile synthesis and characterization of high-performance NiMoO<Subscript>4</Subscript> · <Emphasis Type="Italic">x</Emphasis>H<Subscript>2</Subscript>O nanorods electrode material for supercapacitors

One-dimensional NiMoO₄ · xH₂O nanorods were synthesized by a facile template-free hydrothermal method as a potential electrode material for supercapacitors. The influences of reaction temperature, reaction time, and nickel source on the properties of resultant samples were investigated. Electrochemical data reveal that the as-synthesized one-dimensional NiMoO₄ · xH₂O nanorod superstructures can deliver a remarkable specific capacitance (SC) of 1131 F g^?1 at a current density of 1 A g^?1 and remain as high as 914 F g^?1 at 10 A g^?1 in a 6 M KOH aqueous solution. Moreover, there is only 6.2 % loss of the maximum SC after 1000 continuous charge–discharge cycles at the high current density of 10 A g^?1. Such outstanding electrochemical performance may be owing to the unique one-dimensional hierarchical structures, which can facilitate the electrolyte ions and electrons to easily contact the NiMoO₄ nanorod building blocks and then allow for sufficient faradaic reactions to take place, even at high current densities.     

Protein-directed in situ synthesis of platinum nanoparticles with superior peroxidase-like activity,and their use for photometric determination of hydrogen peroxide

Platinum nanoparticles (Pt-NPs) with sizes in the range from 10 to 30 nm were synthesized using protein-directed one-pot reduction. The model globular protein bovine serum albumin (BSA) was exploited as the template, and the resulting BSA/Pt-NPs were studied by transmission electron microscopy, energy dispersive X-ray spectroscopy, and resonance Rayleigh scattering spectroscopy. The modified nanoparticles display a peroxidase-like activity that was exploited in a rapid method for the colorimetric determination of hydrogen peroxide which can be detected in the 50 μM to 3 mM concentration range. The limit of detection is 7.9 μM, and the lowest concentration that can be visually detected is 200 μM.

Pt-NPs were synthesized using BSA-directed one-pot reduction and BSA/Pt-NPs composite can effectively catalyze the oxidation of TMB producing blue solution in the presence of H₂O₂.

     

Solid‐State Condensation Reactions Between Aldehydes and 5,5‐Dimethyl‐1,3‐cyclohexanedione by Grinding at Room Temperature

An efficient and convenient approach to the synthesis of the two different products from aldehydes and 5,5‐dimethyl‐1,3‐cyclohexanedione in the solid state by grinding is described. This method provides several advantages such as environmental friendliness, high yields, and simple workup procedure.     

Trading N and O: asymmetric syntheses of β-hydroxy-α-amino acids via α-hydroxy-β-amino esters

Both diastereoisomers of 2-amino-3-hydroxybutanoic acid and 2-amino-3-hydroxy-3-phenylpropanoic acid have been prepared from enantiopure α-hydroxy-β-amino esters via the intermediacy of the corresponding cis- and trans-aziridines. Aminohydroxylation of two α,β-unsaturated esters produced enantiopure 2,3-anti-α-hydroxy-β-amino esters in >99:1 dr. Subsequent epimerisation at the C(2)-position via a sequential oxidation/diastereoselective reduction protocol gave the corresponding enantiopure 2,3-syn-α-hydroxy-β-amino esters in >99:1 dr. These syn- and anti-substrates were then converted into the corresponding N-Boc protected cis- and trans-aziridines, respectively, via a three step reaction sequence: (i) hydrogenolysis and in situ N-Boc protection; (ii) OH-activation; and (iii) aziridine formation. Subsequent regioselective ring-opening of the C(3)-methyl-aziridines with Cl₃CCO₂H proceeded with inversion of configuration to give the corresponding 2-amino-3-trichloroacetate esters, whereas the analogous reaction with the C(3)-phenyl-aziridines resulted in rearrangement to the corresponding oxazolidin-2-ones with retention of configuration. In each case, hydrolysis of the products from these ring-opening reactions produced the corresponding enantiopure β-hydroxy-α-amino acids as single diastereoisomers.     

Synthesis,Crystal Structures,and Optical/Electronic Properties of Sphere–Rod Shape Amphiphiles Based on a [60]Fullerene?Oligofluorene Conjugate

A series of sphere–rod shape amphiphiles, in which a [60]fullerene (C₆₀) sphere was connected to the center of an oligofluorene (OF) rod through a rigid linkage (OF‐C₆₀), were designed and synthesized. Alkyl chains of various lengths were attached onto the OFs on both sides of the C₆₀ spheres. These compounds, denoted as alkyl‐OF‐C₆₀, were fully characterized by ¹H NMR, ¹³C NMR, and FTIR spectroscopy and by MALDI‐TOF mass spectrometry. The morphologies and structures of their crystals were elucidated by wide‐angle X‐ray diffraction (WAXD) and by electron diffraction in transmission electron microscopy (TEM). Butyl‐OF‐C₆₀ forms a monoclinic unit cell (a=1.86, b=3.96, c=2.24 nm; α=γ=90°, β=68°; space group P2), octyl‐OF‐C₆₀ also forms a monoclinic unit cell (a=2.21, b=4.06, c=1.81 nm; α=γ=90°, β=75.5°; space group C2m), and dodecanyl‐OF‐C₆₀ forms a triclinic structure (a=1.82, b=4.35, c=2.26 nm; α=93.1°, β=94.5°, γ=92.7°; space group P1). The inequivalent spheres and rods were found to pack into an alternating layered structure of C₆₀ and OF in the crystals, thus resembling a “double‐cable” structure. UV/Vis absorption spectroscopy revealed an electron perturbation between the two individual chromophores (C₆₀ and OF) in their ground states. Fluorescence spectroscopy exhibited complete fluorescence quenching of their solutions in toluene, thus suggesting an effective energy transfer from OF to C₆₀. Cyclic voltammetry indicated that the energy‐level profiles of C₆₀ and OF remained essentially unchanged. This work has broad implications in terms of understanding the self‐assembly and molecular packing of conjugated materials in crystals and has potential applications in organic field‐effect transistors and bulk heterojunction solar cells.     

Fe3O4 nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin for magnetic solid‐phase extraction of carbaryl and carbofuran

In this study, porous sandwich structure Fe₃O₄ nanoparticles coated by polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe₃O₄ nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high‐performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple. The method exhibited a good linearity in the range of 2–400 μg/kg for carbaryl and carbofuran (R² = 0.9995), respectively. The limits of detection were 0.5 μg/kg of carbaryl and 0.7 μg/kg for carbofuran in apple, respectively. Extraction recoveries ranged from 94.2 to 103.1% with the preconcentration factor of 300 and the relative standard deviations were less than 5.9%. These results indicated that the method combined magnetic solid phase extraction with high‐performance liquid chromatography and was promising for the determination of carbaryl and carbofuran at trace amounts.     

Transition‐Metal–Boron Intermetallics with Strong Interatomic d–sp Orbital Hybridization for High‐Performance Electrocatalysis

A theoretical and experimental study gives insights into the nature of the metal–boron electronic interaction in boron‐bearing intermetallics and its effects on surface hydrogen adsorption and hydrogen‐evolving catalytic activity. Strong hybridization between the d orbitals of transition metal (T_M) and the sp orbitals of boron exists in a family of fifteen T_M–boron intermatallics (T_M:B=1:1), and hydrogen atoms adsorb more weakly to the metal‐terminated intermetallic surfaces than to the corresponding pure metal surfaces. This modulation of electronic structure makes several intermetallics (e.g., PdB, RuB, ReB) prospective, efficient hydrogen‐evolving materials with catalytic activity close to Pt. A general reaction pathway towards the synthesis of such T_MB intermetallics is provided; a class of seven phase‐pure T_MB intermetallics, containing V, Nb, Ta, Cr, Mo, W, and Ru, are thus synthesized. RuB is a high‐performing, non‐platinum electrocatalyst for the hydrogen evolution reaction.     

Lie Bialgebras of Generalized Virasoro-like Type

In this paper, Lie bialgebra structures on generalized Virasoro-like algebras are studied. It is proved that all such Lie bialgebras are triangular coboundary.