Synthesis of new pentacyclic diquinothiazines

Reactions of 2,2′‐dichloro‐3,3′‐diquinolinyl sulfide 1 with ammonia derivatives and various primary alkylamines and arylamines proceeded as a thiazine ring closure to form linear annulated pentacyclic 6H‐diquinothiazine 2H and 6‐substituted derivatives 2 with alkyl, alkylaryl, aryl and heteroaryl substituents in moderate to good yields. Reaction with 2‐chloroethylamine did not stop at the formation of half‐mustard derivative 2k but ran to ethylenediquinothiazinium salt 11 . 6H‐Diquinothiazine 2H was N‐alkylated and N‐arylated to give 6‐substituted derivatives 2 . The crucial substrate 1 was obtained from other heteropentacenes 3 and 4 via 1,4‐dithiin ring opening and further transformations. X‐ray analysis of p‐nitrophenyldiquinothiazine 2i revealed unexpected planar thiazine ring.     

Simulation of electroporated cell by chronopotentiometry

Chronopotentiometry on planar lipid bilayer (BLM) is proposed as a method for modeling the electrical phenomena in electroporated cell. Two techniques are discussed: constant-current and linear-current chronopotentiometry. It is proposed that the constant-current chronopotentiometry may provide basis for modeling the electroporated cell shortly after the removal of the electric field, when activity of cellular pumps counteracts ionic fluxes through the electropore and ionic channels. The linear-current method can be considered for modeling the cell in the later stage after electroporation, when energetical resources of the cell are gradually getting exhausted and the activity of pumps decreases. Based on this idea, it may be postulated that the electropore in the cell has fluctuating dynamics whose stochastic characteristics, similarly as biological channels, shows 1/f noise. The model implies that the fluctuations would disappear leaving the electropore with a constant resistance when efficiency of the pumps becomes very small. The results of chronopotentiometry also may suggest that opening time, conductivity and selectivity of the electropore can be controlled by the cell environment or membrane composition.     

Insight into the stereoselectivity of PPL-catalyzed formation of polyesters from phenyl glycidyl ether and succinic anhydride

Analysis of the stereoselectivity that would be expected in the Pig Pancreatic Lipase-catalyzed oligomerization of succinic anhydride and phenyl glycidyl ether is carried out.The results show that no stereoselection was recorded at any step of the suggested mechanism of the process: opening of the chiral epoxide into 1,2-diol, nucleophilic attack of the chiral acylenzyme by a chiral diol, or by the hydroxyl group of a growing oligomer.     

Global optimization of bilinear programs with a multiparametric disaggregation technique

In this paper, we present the derivation of the multiparametric disaggregation technique (MDT) by Teles et al. (J. Glob. Optim., 2011) for solving nonconvex bilinear programs. Both upper and lower bounding formulations corresponding to mixed-integer linear programs are derived using disjunctive programming and exact linearizations, and incorporated into two global optimization algorithms that are used to solve bilinear programming problems. The relaxation derived using the MDT is shown to scale much more favorably than the relaxation that relies on piecewise McCormick envelopes, yielding smaller mixed-integer problems and faster solution times for similar optimality gaps. The proposed relaxation also compares well with general global optimization solvers on large problems.     

Shape-shifting micro- and nanopatterns controlled by temperature

Herein, features that alter their shape to form a different pattern upon an external trigger are described. Electron-beam lithography was used to fabricate micrometer- and nanometer-sized surface immobilized poly(triethylene glycol methacrylate) (pTEGMA) that exhibits significant thermal responsivity; the resulting hydrogels collapsed by up to 95% of their height upon addition of heat. Multicomponent features composed of both the thermoresponsive polymer and nonresponsive poly(ethylene glycol) (PEG) were then prepared. Upon increase in temperature, only the thermally responsive component of the pattern collapsed, causing a significant and predictable alteration in the overall pattern. Reversible micrometer- and nanometer-sized square-to-triangles, squares-to-checkerboards, smiles-to-neutral face, and zeros-to-ones shapes were shown.     

Meshless methods for the inverse problem related to the determination of elastoplastic properties from the torsional experiment

The problem of determining the elastoplastic properties of a prismatic bar from the given experimental relation between the torsional moment M and the angle of twist per unit length of the rod’s length θ is investigated as an inverse problem. The proposed method to solve the inverse problem is based on the solution of some sequences of the direct problem by applying the Levenberg-Marquardt iteration method. In the direct problem, these properties are known, and the torsional moment is calculated as a function of the angle of twist from the solution of a non-linear boundary value problem. This non-linear problem results from the Saint-Venant displacement assumption, the Ramberg–Osgood constitutive equation, and the deformation theory of plasticity for the stress–strain relation. To solve the direct problem in each iteration step, the Kansa method is used for the circular cross section of the rod, or the method of fundamental solutions (MFS) and the method of particular solutions (MPS) are used for the prismatic cross section of the rod. The non-linear torsion problem in the plastic region is solved using the Picard iteration.     

Synthesis and NMR assignment of 1,4-oxathiino[3,2-c;5,6-c']diquinoline

1,4-Oxathiinodiquinoline 3 was obtained in three ways from 1,4-dithiinodiquinolines 1 and 2 via ring opening-ring closure reactions with total yield of 19, 46 and 77%. Through-space interactions between the H-5_quinolinyl atoms and oxygen atom were discussed on the basis of ¹H nmr spectrum.     

Impingement mixing and its effect on the microstructure of RIM polyurethanes

The effect of impingement mixing on the microstructures developed during a reaction injection molding process in a thermoplastic urethane system was investigated. The polyurethane studied was a 4,4′-diphenylmethane diisocyanate/l,4-butane diol/poly(propyleneoxide) end-capped with poly(ethy1eneoxide) polyol system with a 5/4/1 molar ratio. Three different impingement mixing levels ranging from Re = 80 to Re = 210 were implemented by a laboratory RIM machine. The samples were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), optical microscopy, and transmission electron microscopy (TEM). Morphologies of hard-segment globules, hard-segment spherulites, and soft-segment rich matrix were observed. The multiple DSC endotherms were related to different crystalline structures. A higher level of mixing was found to increase the molecular weight and produce more paracrystalline structures. A lower mixing level produced better phase separation and spherulitic structures. High temperature annealing caused transurethanization, which may allow molecular rearrangement and change the crystalline structures.