Synthesis and molecular structure of novel 4‐aryloctahydropyrido‐[1,2‐c]pyrimidine derivatives

A series of new 4‐aryloctahydropyrido[1,2‐c]pyrimidine‐1,3‐diones 6a,b,d‐h and j were synthesized by intramolecular cyclization of α‐aryl‐α‐(1‐ethoxycarbonyl‐2‐piperidyl)‐acetamide derivatives 5a,b,d‐h and j . The structures of compounds were determined by ¹H and ¹³C nmr spectroscopy. Nmr and X‐ray diffraction data indicate that the configuration at the C4, C4a stereocenters constitute RR and SS pair.     

The possibility of detection of finite temperature stripe ordering in 2D spinless Falicov–Kimball model

This paper announces a possibility of detection of finite-temperature stripe ordering in the two-dimensional Falicov–Kimball model at half-filling by extensive Monte Carlo simulations. Moreover, the tools to study orderings and to detect phase transition temperatures are presented. The use of Binder's cumulant is supplemented by finite-size magnetization profiles not analyzed previously in this context. Continuous character of phase transitions is announced. Analyses proving the existence of more complicated phases of finite-temperature stripe ordering than the checkerboard one conclude the paper.     

New Anderson-Based Polyoxometalate Covalent Organic Frameworks as Electrodes for Energy Storage Boosted Through Keto-Enol Tautomerization

The unique electrochemical properties of polyoxometalates (POMs) render them ideal components for the fabrication of next-generation high-performance energy storage systems. However, their practical applications have been hindered by their high solubility in common electrolytes. This problem can be overcome by the effective hybridization of POMs with other materials. Here we present the design and synthesis of two novel polyoxometalate-covalent organic frameworks (POCOF) via one-pot solvothermal strategy between an amino-functionalized Anderson-type POM and a trialdehyde-based building unit. We show that structural and functional complexity can be enriched by adding hydroxyl groups in the 2,4,6 position to the benzene-1,3,5-tricarbaldehyde allowing to exploit for the first time in POCOFs the keto-enol tautomerization as additional feature to impart greater chemical stability to the COFs and enhanced properties leading to large specific surface area (347 m²/g) and superior electrochemical performance of the POCOF-1 electrodes, when compared with POCOF-2 electrodes that possess only imine-type linkage and with pristine POM electrodes. Specifically, POCOF-1 electrodes display remarkable specific, areal, and volumetric capacitance (125 F/g, 248 mF/cm² and 41.9 mF/cm³, respectively) at a current density of 0.5 A/g, a maximum energy density (56.2 Wh/kg), a maximum power density (3.7 kW/kg) and an outstanding cyclability (90 % capacitance retention after 5000 cycles).     

Enzymatic removal of carboxyl protecting groups. 2. Cleavage of the benzyl and methyl moieties

[reaction: see text] Enzymes are versatile reagents for the efficient removal of methyl and benzyl protecting groups. An esterase from Bacillus subtilis (BS2) and a lipase from Candida antarctica (CAL-A) allow a mild and selective removal of these moieties in high yields without affecting other functional groups.     

Magnetic thermoelectric power of Fe20Ni60B10Si10 metallic glass

The magnetic contribution to the thermoelectric power was separated for the metallic glass Fe₂₀Ni₆₀B₁₀Si₁₀ which exhibits the ferro-paramagnetic transition at T_c = 455 K remarkably below the crystallization threshold T_x = 670 K. Results are compared with the predictions of the Kasuya theory.     

Renormalization of a non-renormalizable quantum field theory

We present a rigorous construction of the continuum limit for a perturbatively non-renormalizable euclidean quantum field theory: the Gross-Neveu model in two dimensions with bare propagator $\textcolor{red}{}\text{/|p|}{}^{\mathrm{2??}}$ for ?>0 small. The construction proceeds via the control of the flow of Wilson's renormalization group around the non-gaussian ultraviolet stable fixed point in the space of effective actions.     

σ-bond conjugation in polysilanes,a pes scaled free-electron approach for the interpretation of skeletal cleavage reactions

The σ-orbital energies calculated by the simple free-electron model with a parametrization procedure proposed recently by Von Szentplay correlate very closely with the σ-band positions of the corresponding photoelectron spectra. For the σ-orbitals of three series of molecules: H(CH₂)_nH (n = 2–4); H(SiH₂)_nH (n = 2–5); Me(SiMe₂)_nMe (n = 2–4) the FEMO model yields a standard error SE) of 0.060 eV. Compared with HMO results (LCGO, LCBO and Sandorfy C) the correlation is significantly improved. The free-electron results are more accurate than those obtained using the PPP, CNDO/2, MINDO/3, SAMO and ab initio methods.The free-electron frontier orbital densities were successfully used to account for features of the skeletal cleavage reactions of polysilanes.     

Thermal stability of collagen in naturally ageing and in vitro glycated rabbit tissues

Journal of Thermal Analysis and Calorimetry - The aim of the work was to compare glycation-related changes in thermal denaturation of collagen in naturally ageing and in vitro ribosylated tissues....