Trap-assisted tunnelling current in MIM structures

A new model is presented of current transport in Metal Insulator Metal (MIM) structures by quantum mechanical tunnelling. In addition to direct tunnelling through an insulating layer, tunnelling via defects present in the insulating layer plays an important role. Examples of the influence of the material and thickness of the insulating layer, energy distribution of traps, and metal work functions are also provided.     

On symmetry properties of parabolic equations in bounded domains

We study symmetry properties of nonnegative bounded solutions of fully nonlinear parabolic equations on bounded domains with Dirichlet boundary conditions. We propose sufficient conditions on the equation and domain, which guarantee asymptotic symmetry of solutions.     

Enantiomeric separation of 1,3‐dimethylamylamine by capillary electrophoresis with indirect UV detection using a dual‐selector system

The CE method employing an indirect UV detection for the enantioseparation of 1,3‐dimethylamylamine (DMAA), widely used in various preworkout and dietary supplements labeled as a constituent of geranium extract has been developed. The dual‐selector system consisting of negatively charged sulfated α‐CD (1.1% w/v) and sulfated β‐CD (0.2% w/v) in 5 mM phosphate/Tris buffer (pH 3.0) containing the addition of 10 mM benzyltriethylammonium chloride (BTEAC) as the chromophoric additive was used for the enantiomeric separation of DMAA stereoisomers with the LODs in the range of 7.82–9.24 μg/mL. The method was partly validated and applied for the determination of the stereoisomeric composition of DMAA in commercial dietary supplements to verify the potential natural origin of DMAA.     

Robust model-based predictive control of exothermic chemical reactor

A case study of the robust model-based predictive control (MPC) of an exothermic continuous stirred tank reactor (CSTR) with uncertain parameters is presented. Three robust MPC approaches are considered and the simulation results are compared in terms of quality of control performance and total consumption of coolant. The results reveal the main benefits of the considered approaches and confirm that the robust MPC can bring about a reduction in consumption of the coolant.     

Photoinduced superoxide radical anion and singlet oxygen generation in the presence of novel selenadiazoloquinolones (an EPR Study)

Novel 7‐substituted 6‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐h]quinoline ( SeQ(1–6) ) and 8‐substituted 9‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐f ]quinoline derivatives ( SeQN(1–5) ) with R₇, R₈ = H, COOC₂H₅, COOCH₃, COOH, COCH₃ or CN were synthesized and their spectral characteristics were obtained by UV/Vis spectroscopy. Ultraviolet A photoexcitation of the selenadiazoloquinolones in dimethylsulfoxide or acetonitrile resulted in the formation of paramagnetic species coupled with molecular oxygen activation generating the superoxide radical anion or singlet oxygen, evidenced by electron paramagnetic resonance spectroscopy. The cytotoxic/photocytotoxic impact of selenadiazoloquinolones on murine and human cancer cell lines was demonstrated using the derivative SeQ5 (with R₇ = COCH₃).     

Synthesis of trihydroxylated pyrrolizidine and indolizidine alkaloids based on SmI2-induced reductive coupling of chiral nitrones with methyl acrylate

Synthesis of trihydroxylated pyrrolizidines, the enantiomer of 2-epihyacinthacine A₂ and indolizidine analogues of the natural alkaloids is reported. The key step of these syntheses is the stereoselective samarium diodide-induced coupling of the chiral nitrone prepared from d-ribose with methyl acrylate. The nitrone derived from d-ribose possessing C2/C3 syn configuration reacted with methyl acrylate in the presence of samarium diiodide in excellent yield and diastereoselectivity, with only the anti-diastereomer being detected.     

Synthesis and characterization of two homologous series of diastereomeric 2-alkoxyphenylcarbamates

Two homologous series of racemic diastereomeric cis- and trans-(2-dimethylaminomethylcycloheptyl)-2-alkoxyphenylcarbamates with alkyl chain lengths ranging from C? to C? were synthesized by stereoselective reactions. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR and IR spectroscopy and their physico-chemical properties were characterized. The two new series of diastereomeric compounds were tested for their local anesthetic activity and parabolic relationship between the local anesthetic activity and lipophilicity was found for both cis- and trans-series. Interestingly, cis-stereoisomers exhibited higher local anesthetic activity.     

Complex scaling and Lyapunov converters

It is proved that for a certain class of potentials dilation operators used in the method of complex scaling (CSM ) represent a special case of Lyapunov converters. The time evolution of quantum systems is investigated from the viewpoint of this result, with special emphasis on the time evolution of resonant functions. © 1993 John Wiley & Sons, Inc.     

On a-Posteriori Error Estimate of Approximate Solutions to a Mildly Nonlinear Nonpotential Elliptic Boundary Value Problem

The paper deals with the construction of a computable a-posteriori error estimate of the approximate solution to some nonpotential nonlinear elliptic boundary value problems. The convergence of the presented error estimate to the true error is proved. The method is illustrated on some numerical examples.     

Some less usual properties of tetracyano complexes

The structure and reactivity of one unique molecule may be understood only in relation to its molecular surroundings. The non-stoichiometric forms of the tetracyano complexes M(B) _mM (CN)₄·nG (B=nitrogen or oxygen containing base; G=aromatic compound or H₂O,m0,n>0) are understood in this respect. Their stoichiometric or non-stoichiometric forms, with voids either completely or more often partially occupied, are responsible for their observed sorptive and resorptive abilities. The effects of the surroundings are correlated with the results of thermal analysis, magnetic measurements and their sorptive abilities.Dedicated to Professor H. M. Powell.