A new strategy of the chemical route to the cyclopropane structure: direct transformation of benzylidenemalononitriles and malononitrile into 1,1,2,2-tetracyanocyclopropanes

The new reaction was found: the direct formation of cyclopropanes from activated olefins and C-H acids. The action of free halogen or active halogen containing compounds on the equal amounts of benzylidenemalononitriles and malononitrile in basic alcohol solutions results in the formation of 3-aryl-1,1,2,2-tetracyanocyclopropanes in 65-95% yields. Thus, the new simple and efficient way to 3-aryl substituted tetracyanocyclopropanes was found directly from such simple and reasonable starting compounds as benzylidenemalononitriles and malononitrile.     

Mesoporous Activated Carbon from Agricultural Byproducts

 Several different activated carbons have been prepared, from olive stones, solvent-extracted olive pulp and peach stones. Both a two-step procedure, carbonization followed by steam activation, and a single-step procedure, carbonization and activation in a single stage, have been applied at temperatures from 770 to 850 °C. The effect of such variables as heating rate during carbonization and activation, final temperature, soaking time and starting material, on the development of pore structure, have been investigated. Porosity and surface area have been evaluated by adsorption of nitrogen at 77 K. Mesoporosity and macroporosity were determined by mercury porosimetry. Scanning electron microscopy and X-ray diffraction analysis revealed useful information on the surface texture and structure respectively. Two-step physical activation of olive stones, with steam, yielded mesoporous structures. Extended time of activation favoured mesopore development. The parent olive stones showed the most homogeneous surfaces. All the activated carbons prepared were amorphous. Their well-developed porosity and large surface area combined with their chemical composition render the activated carbons from agricultural by-products an attractive product.     

Solvent-free cascade reaction: direct multicomponent assembling of 2-amino-4H-chromene scaffold from salicylaldehyde, malononitrile or cyanoacetate and nitroalkanes

The new type of solvent-free cascade reaction was found: the direct heating of the mixture of salicylaldehyde, malononitrile or cyanoacetate and nitroalkanes at 60 °C in the presence of catalytic amounts of KF or NaOAc results in the formation of 2-amino-4-(1-nitroalkyl)-4H-chromene-3-carbonitriles or methyl 2-amino-4-(1-nitroalkyl)-4H-chromene-3-carboxylates in 80-90% yields. Thus, the new simple and efficient solvent-free ‘one-pot’ way to substituted medicinally privileged 2-amino-4H-chromene scaffold was found directly from such simple and reasonable starting compounds as salicylaldehyde, malononitrile or cyanoacetate and nitroalkanes.     

Coarse-grained computation for particle coagulation and sintering processes by linking Quadrature Method of Moments with Monte-Carlo

The study of particle coagulation and sintering processes is important in a variety of research studies ranging from cell fusion and dust motion to aerosol formation applications. These processes are traditionally simulated using either Monte-Carlo methods or integro-differential equations for particle number density functions. In this paper, we present a computational technique for cases where we believe that accurate closed evolution equations for a finite number of moments of the density function exist in principle, but are not explicitly available. The so-called equation-free computational framework is then employed to numerically obtain the solution of these unavailable closed moment equations by exploiting (through intelligent design of computational experiments) the corresponding fine-scale (here, Monte-Carlo) simulation. We illustrate the use of this method by accelerating the computation of evolving moments of uni- and bivariate particle coagulation and sintering through short simulation bursts of a constant-number Monte-Carlo scheme.     

Notiz über das Gleichgewicht eines schweren Drahtes,dessen Axe eine Schraubenlinie bildet

Ohne Zusammenfassung     

Quantum Neural Nets

The capacity of classical neurocomputers islimited by the number of classical degrees of freedom,which is roughly proportional to the size of thecomputer. By contrast, a hypothetical quantumneurocomputer can implement an exponentially larger number ofthe degrees of freedom within the same size. In thispaper an attempt is made to reconcile the linearreversible structure of quantum evolution with nonlinear irreversible dynamics for neuralnets.     

Acid-Catalyzed Reaction of (4,4-Diethoxybutyl)ureas with Phenols as a Novel Approach to the Synthesis of α-Arylpyrrolidines

1-(4,4-Diethoxybutyl)-3-alkylureas undergo intramolecular cyclization in the presence of trifluoroacetic acid and various phenols, leading to the new N-alkyl-2-arylpyrrolidine-1-carboxamides with moderate to excellent yields. It was found that these compounds undergo spontaneous solid-phase epimerization at room temperature. Advantages of the proposed approach are mild reaction conditions and no need for expensive reagents or catalysts.     

Temperature effects on the structure and dynamics of liquid dimethyl sulfoxide: A molecular dynamics study

The molecular dynamics (MD) simulation technique has been employed to investigate the thermodynamic properties and transport coefficients of the neat liquid dimethyl sulfoxide (DMSO). The fluid has been studied at temperatures in the range 298–353 K and at a pressure equal to 1 atm. The simulations employed a nine-site potential model, which is presented for the first time here, and all the available non-polarizable models. The performance of each model is tested using the same statistical mechanical ensemble and simulation method under the same conditions, revealing its weaknesses and strengths. Thermodynamic properties, microscopic structure and dynamic properties, such as transport coefficients, rotational and single-dipole correlation times have been calculated and compared with available experimental results. Estimations of transport coefficients from various theoretical and empirical models are tested against experimental and MD results. Translational and rotational dynamics suggest the existence of the cage effect and agree with the Stokes–Einstein–Debye relation. The dipole relaxation times calculated are discussed in terms of simple and useful approximations, such as the Glarum–Powles and Fatuzzo–Mason models.     

Optical sensing quantum dot-labeled polyacrolein particles prepared by layer-by-layer deposition technique

Optical sensing polymer particles with tailored semiconductor nanocrystal (QD) loading are prepared by layer-by-layer deposition technique (LbL). Polyacrolein particles of 1.2 μm diameter are used as solid support for deposition of hydrophilic CdSe/ZnS nanocrystal/polyelectrolyte multilayers formed by electrostatic interactions. The pH-dependent fluorescence of QDs and pH-dependent conformations of polyelectrolytes, which likely passivate the surface state of nanocrystals, allow a creation of both mono- and multiplex coded polymer particles with pH-dependent fluorescence intensity. Bovine serum albumin (BSA) as outermost layer makes it possible to design the optical sensing polymer particles with reversibly responded fluorescence at pH variations. The fluorescence of such polymer particles with BSA outer layer is sensitive to copper(II) ion while the fluorescence of these particles is practically insensitive to the other divalent cations (Zn(2+), Ca(2+), Ba(2+), Co(2+), Mg(2+)). The detection limit of Cu(2+) is about 15 nM. Adaptation of LbL method to prepare QD-labeled polymer particles with enhanced complexity (e.g. several types of QDs, multiple biofunctionality) is expected to open new opportunities in biotechnological applications.