Efficient syntheses of the versatile phthalide building blocks, 5,6-diaminoisobenzofuran-1(3H)-one and 5H,7H-furo[3,4-f][2,1,3]benzothiadiazol-5-one

A new and efficient synthesis of 5,6-diaminophthalide and a novel thiadiazolophthalide has been accomplished. Both molecules are useful starting compounds for the construction of more complex heterocyclic systems and for the preparation of bioisosteres of methylenedioxyphenyl derivatives.     

Generation Expansion Planning Model Supporting Diverse Environmental Policies for Reduction of Greenhouse Gases

The purpose of this paper is to a develop model for generation expansion planning that can support diverse environmental policies for the reduction of greenhouse gases (GHGs) of South Korea. South Korea is required to reduce its GHG emissions by 30% from the BAU level by 2020. The Wien Automatic System Planning Package currently used in South Korea has limitations in terms of the application of renewable energy policies and GHG targets; this paper proposes the use of an equipment planning model named generation and transmission expansion program, which has been developed to resolve such limitations. For verification of the model, a case study on the 6th Basic Plan of Long‐Term Electricity Supply and Demand has been conducted. The results show that for the year 2020 South Korea's annual GHG emissions will be 36.6% more than the GHG Target Management System (GHG TMS) target set for the same year (30%). To achieve the GHG TMS target, the costs involved amount to about 72 trillion KRW (70 billion USD). Consequently, the South Korean government needs to review the performability of this target.     

The t-Tone Chromatic Number of Random Graphs

A proper 2-tone k-coloring of a graph is a labeling of the vertices with elements from \({\binom{[k]}{2}}\) such that adjacent vertices receive disjoint labels and vertices distance 2 apart receive distinct labels. The 2-tone chromatic number of a graph G, denoted τ ₂(G) is the smallest k such that G admits a proper 2-tone k coloring. In this paper, we prove that w.h.p. for \({p\geq Cn^{-1/4} {\rm ln}^{9/4}n, \tau_2(G_{n, p}) = (2 + o(1))\chi(G_{n, p})}\) where \({\chi}\) represents the ordinary chromatic number. For sparse random graphs with p = c/n, c constant, we prove that \({\tau_2(G_{n, p}) = \lceil{({\sqrt{8\Delta + 1} + 5})/{2}}}\) where Δ represents the maximum degree. For the more general concept of t-tone coloring, we achieve similar results.     

ORGANOBISMUTH HOMOCYCLES (RBi)n AND HETEROCYCLES (RBiS)2

The homocycles (RBi)_n (n = 3–5) react with MeC₅ H₄Mn(CO)₂(thf) (thf = tetrahydrofuran) or Fe₂(CO)₉ to give Bi₂[Mn(CO)₂MeC₅ H₄]₃ (1) or Bi₂Fe₃(CO)₉ (3). Reaction of R₄Bi₂ (R = Me₃SiCH₂) with Fe₂(CO)₉ in toluene gives R₂Bi₂Fe₂(CO)₈ (4) and R₄Bi₂Fe(CO)₄ (5). The heterocycles (RBiS)₂(R = 2-(Me₂NCH₂)C₆ H₄ (6), 2, 6-(Me₂NCH₂)₂ C₆ H₄ (7) are formed by reaction of the corresponding dihalides RBiCl₂ with Na₂S. The reaction of (RBiS)₂(R = 2-(Me₂NCH₂)C₆ H₄) with W(CO)₅(thf) leads to (RBiS)₂[W(CO)₅]₂ (8).     

90 GW peak power few-cycle mid-infrared pulses from an optical parametric amplifier

We demonstrate a compact 20 Hz repetition-rate mid-IR OPCPA system operating at a central wavelength of 3900 nm with the tail-to-tail spectrum extending over 600 nm and delivering 8 mJ pulses that are compressed to 83 fs (<7 optical cycles). Because of the long optical period (～13 fs) and a high peak power, the system opens a range of unprecedented opportunities for tabletop ultrafast science and is particularly attractive as a driver for a highly efficient generation of ultrafast coherent x-ray continua for biomolecular and element specific imaging.     

Non‐Equilibrium Polymerization of Cross‐β Amyloid Peptides for Temporal Control of Electronic Properties

Hydrophobic collapse plays crucial roles in protein functions, from accessing the complex three‐dimensional structures of native enzymes to the dynamic polymerization of non‐equilibrium microtubules. However, hydrophobic collapse can also lead to the thermodynamically downhill aggregation of aberrant proteins, which has interestingly led to the development of a unique class of soft nanomaterials. There remain critical gaps in the understanding of the mechanisms of how hydrophobic collapse can regulate such aggregation. Demonstrated herein is a methodology for non‐equilibrium amyloid polymerization through mutations of the core sequence of Aβ peptides by a thermodynamically activated moiety. An out of equilibrium state is realized because of the negative feedback from the transiently formed cross‐β amyloid networks. Such non‐equilibrium amyloid nanostructures were utilized to access temporal control over its electronic properties.     

Selective Formation and Unusual Reactivity of Tetraarsabicyclo[1.1.0]butane Complexes

The selective formation of the dinuclear butterfly complexes [{Cp′′′Fe(CO)₂}₂(μ,η^1:1‐E₄)] (E=P ( 1 a ), As ( 1 b )) and [{Cp*Cr(CO)₃}₂(μ,η^1:1‐E₄)] (E=P ( 2 a ), As ( 2 b )) as new representatives of this rare class of compounds was found by reaction of E₄ with the corresponding dimeric carbonyl complexes. Complexes 1 b and 2 b are the first As₄ butterfly compounds with a bridging coordination mode. Moreover, first studies regarding the reactivity of 1 b and 2 b are presented, revealing the formation of the unprecedented As₈ cuneane complexes [{Cp′′′Fe(CO)₂}₂{Cp′′′Fe(CO)}₂(μ₄,η^1:1:2:2‐As₈)] ( 3 b ) and [{Cp*Cr(CO)₃}₄(μ₄,η^1:1:1:1‐As₈)] ( 4 ). The compounds are fully characterized by NMR and IR spectroscopy as well as by X‐ray structure analysis. In addition, DFT calculations give insight into the transformation pathway from the E₄ butterfly to the corresponding cuneane structural motif.     

Planar S-systems: Permanence

We characterize permanence of planar S-systems. Further, we construct a planar S-system with three limit cycles.     

A laterally graded junctionless transistor

This paper proposes a laterally graded junctionless transistor taking peak doping concentration near the source and drain region, and a gradual decrease in doping concentration towards the center of the channel to improve the I OFF and I ON/I OFF ratio. The decrease of doping concentration in the lateral direction of the channel region depletes a greater number of charge carriers compared to the uniformly doped channel in the OFF-state,which in turn suppresses the OFF state current flowing through the device without greatly affecting the ON state current.     

Contractors and connectors of graph algebras

We study generalizations of the “contraction‐deletion” relation of the Tutte polynomial, and other similar simple operations, to other graph parameters. The question can be set in the framework of graph algebras introduced by Freedman at al [Reflection positivity, rank connectivity, and homomorphisms of graphs, J. Amer. Math. Soc. 20 (2007), 37–51.] Graph algebras are defined by a graph parameter, and they were introduced in order to study and characterize homomorphism functions. We prove that for homomorphism functions, these graph algebras have special elements called “contractors” and “connectors”. This gives a new characterization of homomorphism functions. © 2008 Wiley Periodicals, Inc. J Graph Theory 60: 11–30, 2009