Electrochemical Oxidation of Catechols (=Benzene‐1,2‐diols) in the Presence of Benzoylacetonitrile: Synthesis of New Derivatives of 5,6‐Dihydroxybenzofuran

The electrochemical oxidation of catechol (=benzene‐1,2‐diol; 1a ) and some of its derivatives in H₂O/MeCN 1 : 1 containing benzoylacetonitrile (=β‐oxobenzenepropanenitrile; 3 ) as a nucleophile was studied by cyclic voltammetry and controlled‐potential coulometry. The voltammetric data showed that electrochemically generated o‐benzoquinones (=cyclohexa‐3,5‐diene‐1,2‐diones) from catechol ( 1a ) and 3‐methylcatechol ( 1b ) participate in a Michael‐addition reaction with 3 to form the corresponding 5,6‐dihydroxybenzofuran‐3‐carbonitrile 8 (Scheme 1). In this work, we report an efficient one‐pot method with high atom economy for the synthesis of new substituted 5,6‐dihydroxybenzofuran‐3‐carbonitriles in an undivided cell under ambient conditions.     

Electrochemical oxidation of 2,3-dimethylhydroquinone in the presence of 1,3-dicarbonyl compounds

The electrooxidation of 2,3-dimethylhydroquinone (1) has been studied in the presence of 2-phenyl-1,3-indandione (3a), 3-hydroxy-1H-phenalen-1-one (3b), and 2-chloro-5,5-dimethyl-1,3-cyclohexanedione (3c) as CH acid nucleophiles in water/acetonitrile (85/15) solution, using cyclic voltammetry and controlled-potential coulometry. The results indicate that p-benzoquinone, generated by electrochemically driven oxidation of the 2,3-dimethylhydroquinone (1), is scavenged by 3a-c, to give related products (5a, 9b, 8c) via various electrochemical mechanisms. The electrochemical syntheses of 5a, 9b, and 8c have been successfully performed in one-pot in an undivided cell using an environmentally friendly method with high atomic economy.     

Measurement of Dissolved Oxygen in Biological Fluids by Using a Modified Carbon Paste Electrode

A modified carbon paste electrode was constructed for the determination of dissolved oxygen using diamino‐o‐benzoquinone (DABQ) as the modifier. The electrochemical behavior of the electrode in citrate buffer (pH 2.0) was studied. In the presence of dissolved oxygen (DO) both cathodic and anodic peak currents decreased, indicating a chemical reaction between modifier and O₂. The decrease in peak current was linearly proportional to the amount of dissolved oxygen in the concentration range of 252–1260 μM of DO. The electrode was utilized in the determination of DO in urine samples. The relative error and RSD of the method were 1.6% and 4.1%, respectively. The electrode was applied more than two months for the determination of DO without any significant divergence in its voltammetric response.     

Network flow formulation of optimal perimeter sensory coverage problem

In this article, the perimeter detection optimization problem in field surveillance and target tracking are discussed. The detection range of sensors is assumed to be circular or elliptical. Sensors are also assumed to be associated with a cost factor reflecting their operational characteristics and power usage. We show that the problem of optimal sensor selection can be reduced to a network flow problem and can then be solved using any existing classical methodology. This significantly reduces the computational time of sensory selection problem which in many cases needs to be solved in almost real time basis, every time that the dynamics of the field changes. The field dynamics could change due to such events as wind direction change and sensor failures.     

Analysis of strained double-lightly doped MOSCNT using NEGF

The effects of uniaxial and torsional strains on the double-lightly doped MOSCNT (DLD-MOSCNT) performances are investigated, using the non-equilibrium Green function (NEGF) formalism in mode space approach. The Hamiltonian of the device is obtained by a tight-binding approximation assuming that only p _z orbitals are contributing in carrier transport. In all simulation processes, one mode with the lowest subband is considered. DLD-MOSCNT has a small band-to-band tunneling and almost eliminates the ambipolar behavior of I _DS–V _GS characteristics because of the band engineering. We use a modified model to demonstrate the strain effects on such a low OFF-current device. The results show that the strain effects mainly depend on the chiral vector and diameter of CNT. The strain causes band gap and carrier velocity changes, which result in variation of ON- or OFF-current. In addition, the subthreshold swing of this device under uniaxial strain is calculated, which is about 61 mV/Dec for 2 % tensile strain in (16,0) and for ?2 % compressive strain in (17,0). Under the uniaxial strain, in the case that the energy band gap increases, the variation of DIBL is very small.     

Caustic Singularity in Ho?ava-Lifshitz Gravity

In this note we search for a family of solutions with Caustic singularity in non relativistic-renormalizable Hořava-Lifshitz (HL) theory without the general covariant. We show that in infrared (IR) limit and with a deviation from λ=1 we have no caustic singularity. Also in ultraviolet (UV) regime and for Ricci flat 3-dimensional (3d) spaces and codimension 1 and for λ≠1 the non linear terms should help bouncing this kind of most dangerous would be caustics. But if 3d curvature does not vanish, higher curvature terms do help caustics even in codimension one. Thus the arguments in (J. Cosmol. Astropart. Phys. 0909:005, 2009) are satisfied correctly.     

Redox-Bipolar Polyimide Two-Dimensional Covalent Organic Framework Cathodes for Durable Aluminium Batteries

Emerging rechargeable aluminium batteries (RABs) offer a sustainable option for next-generation energy storage technologies with low cost and exemplary safety. However, the development of RABs is restricted by the limited availability of high-performance cathode materials. Herein, we report two polyimide two-dimensional covalent organic frameworks (2D-COFs) cathodes with redox-bipolar capability in RAB. The optimal 2D-COF electrode achieves a high specific capacity of 132 mAh g⁻¹. Notably, the electrode presents long-term cycling stability (with a negligible ≈0.0007 % capacity decay per cycle), outperforming early reported organic RAB cathodes. 2D-COFs integrate n-type imide and p-type triazine active centres into the periodic porous polymer skeleton. With multiple characterizations, we elucidate the unique Faradaic reaction of the 2D-COF electrode, which involves AlCl²⁺ and AlCl₄⁻ dual-ions as charge carriers. This work paves the avenue toward novel organic cathodes in RABs.