Analogues du nor-B benzomorphane. I. Synthese des méthano-3,5 tétrahydro-2,3,4,5 1H-benzazépines et dérivés

A series of new homologous B-norbenzomorphans, the 3,5-methano-2,3,4,5-tetrahydro-lH-l- and 2-benzazepines inculding 7- and 8-intro or amino derivatives have been synthesized as potential CNS drugs.     

Analysis, simulation and experimental study of chaotic behaviour in parallel-connected DC–DC boost converters

The paper describes an experimental study of the bifurcation behaviour of a modular peak current-mode controlled DC–DC boost converter. The parallel-input/parallel-output converter comprises two identical boost circuits and operates in the continuous-current conduction mode. A comparison is made between the results obtained from an experimental converter with those obtained from bifurcation diagrams generated from previous work and waveforms from a new MATLAB/SIMULINK simulation presented in this paper. Another comparison is made between the modular converter diagrams with those of the single boost converter.     

Design,two-directional synthesis,DFT study of new pyrimido[5,4-d]pyrimidine-2,8-dione derivatives

A facile two-directional synthesis of new pyrimido[5,4-d]pyrimidine-2,8-dione was reported via an efficient reaction of premade bis-aldehydes and 1-(2-amino-1,2-dicyanovinyl)-3-phenylurea in the presence of triethylamine as the base and Cu (II) as catalyst. As there is controversy about the formation of two types of products, that is, purine or pyrimidine ring containing compounds in the reaction of diaminomaleonitrile with isocyanates and aldehydes, the computational model chemistry has been employed to obtain new insight about this reaction and determining the dominant pathway of the process. Using DFT model, two alternative pathways have been explored and geometrical isomerization of central double bond has been considered. Accordingly, the evaluated energy barriers affirm the formation of six-membered pyrimidine ring as the major product in the presence of CuCl₂ as the catalyst and MeOH as solvent.     

Chemistry of 2,3-Dichloroquinoxalines

This review describes the synthesis, reactivity, and the utility of 2,3-dichloroquinoxalines as synthetic intermediates for the synthesis of condensed heterocycles with pharmacological interest.     

Quantitative Tortuosity Measurements of Carbonate Rocks Using Pulsed Field Gradient NMR

Transport in Porous Media - Tortuosity is an important physical characteristic of porous materials; for example, it is a critical parameter determining the effective diffusion coefficient dictating...     

Silicon nanoparticle charge trapping memory cell

A charge trapping memory with 2 nm silicon nanoparticles (Si NPs) is demonstrated. A zinc oxide (ZnO) active layer is deposited by atomic layer deposition (ALD), preceded by Al₂O₃ which acts as the gate, blocking and tunneling oxide. Spin coating technique is used to deposit Si NPs across the sample between Al₂O₃ steps. The Si nanoparticle memory exhibits a threshold voltage (V_t) shift of 2.9 V at a negative programming voltage of –10 V indicating that holes are emitted from channel to charge trapping layer. The negligible measured V_t shift without the nanoparticles and the good re‐ tention of charges (>10 years) with Si NPs confirm that the Si NPs act as deep energy states within the bandgap of the Al₂O₃ layer. In order to determine the mechanism for hole emission, we study the effect of the electric field across the tunnel oxide on the magnitude and trend of the V_t shift. The V_t shift is only achieved at electric fields above 1 MV/cm. This high field indicates that tunneling is the main mechanism. More specifically, phonon‐assisted tunneling (PAT) dominates at electric fields between 1.2 MV/cm < E < 2.1 MV/cm, while Fowler–Nordheim tunneling leads at higher fields (E > 2.1 MV/cm). (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)