Natural networks as thermodynamic systems

Natural networks are considered as thermodynamic systems that evolve from one state to another by consuming free energy. The least-time consumption of free energy is found to result in ubiquitous scale-free characteristics. The network evolution will yield the scale-independent qualities because the least-time imperative will prefer attachment of nodes that contribute most to the free-energy consumption. The analysis of evolutionary equation of motion, derived from statistical physics of open systems, reveals that evolution of natural networks is a path-dependent and nondeterministic process. Despite the noncomputability of evolution, many mathematical models of networks can be recognized as approximations of the least-time process as well as many measures of networks can be appreciated as practical assessments of the system's thermodynamic status. © 2012 Wiley Periodicals, Inc. Complexity, 2012     

Refined optimality conditions for differences of convex functions

We provide a necessary and sufficient condition for strict local minimisers of differences of convex (DC) functions, as well as related results pertaining to characterisation of (non-strict) local minimisers, and uniqueness of global minimisers.     

Stability of Saddle Points Via Explicit Coderivatives of Pointwise Subdifferentials

We derive stability criteria for saddle points of a class of nonsmooth optimization problems in Hilbert spaces arising in PDE-constrained optimization, using metric regularity of infinite-dimensional set-valued mappings. A main ingredient is an explicit pointwise characterization of the regular coderivative of the subdifferential of convex integral functionals. This is applied to several stability properties for parameter identification problems for an elliptic partial differential equation with non-differentiable data fitting terms.     

Novel Nanostructured Electrodes Obtained by Pyrolysis of Composite Polymeric Materials

In this work, we compare pyrolyzed carbon derived from the photoresist SU‐8 alone or in combination with polystyrene and poly(styrene)‐block‐poly(dimethylsiloxane) copolymer (PS‐b‐PDMS), to be used as novel materials for micro‐ and nanoelectrodes. The pyrolyzed carbon films are evaluated with scanning electron microscopy, thermal gravimetric analysis, X‐ray photoelectron spectroscopy, contact angle analysis, and Raman spectroscopy. Furthermore, the standard rate constant for electron transfer is determined from cyclic voltammograms and found to be lower for PS‐b‐PDMS compared to PS and SU‐8 films. This may be related to the lower carbon content of PS‐b‐PDMS, as well as to its higher microstructural disorder.     

Utilisation of customer feedback in a university hospital laboratory

The article describes the customer feedback system at a university hospital laboratory and the analysis of the feedback data from clinical customers in 2001–2006. The most common subject matters of the feedback were suspicion of the validity of laboratory results, delay in service and lacking test results, covering 82% of the 115 reports. The investigations of the cases revealed errors or defects in laboratory services in 81 cases. The most common errors or defects were erroneous test results (35 cases; 43%), delayed test results (24 cases; 30%) and lacking test results (15 cases; 18%). The most common underlying causes for a laboratory error or defect were unintended errors and non-compliance with operating instructions. Seventy-six percent of the feedback reports led to corrective actions. It is important to react to every instance of customer feedback and to find out possible errors or defects in the laboratory process. Uncovering the underlying causes makes adequate corrective and preventive actions possible.     

Structural, thermoanalytical and molecular modeling studies on N-(3-hydroxypropyl) 3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-amide and its monohydrates

The synthetic method for preparing N-(3-hydroxypropyl) 3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-amide can lead to formation of at least three different crystal forms - an anhydrous compound and two monohydrates. The structural and thermal properties of these forms have been characterized by 13C-CP/MAS-NMR and IR spectroscopy, thermo- gravimetry, differential scanning calorimetry and by powder and single crystal x-ray crystallography. In addition, theoretical 13C-NMR chemical shift calculations were also performed for the anhydrous compound and for the first monohydrate, starting from single crystal structures and the structures of these species have now been verified. The first monohydrate, C27H47NO4 x H2O, crystallizes in orthorhombic space group P2(1)2(1)2(1) with cell parameters: a = 7.1148(2), b = 18.1775(5), c = 20.1813(6), Z = 4.     

Structural studies on lithocholyl-N-(2-aminoethyl)amide in the solid state

The synthetic procedure of lithocholyl-N-(2-aminoethyl)amide yielded a mixture of several forms detected by solid state ¹³C CP/MAS NMR although the solution state NMR unambiguously ascertained that the compound was pure. By recrystallization from various solvents one pure polymorph alongside with four solvates were isolated. The structures of the pure polymorph and the solvates were characterized by ¹³C and ¹⁵N CP/MAS NMR and powder X-ray diffraction (PXRD) methods. Variable contact time and dipolar dephasing experiments were employed to obtain optimized CP parameters and to distinguish various CH _n (n = 0–3) resonances. CSA analyses of spinning side bands at different spinning rates showed small variations in the shielding tensor values of the carbonyl group between the pure polymorph (recrystallized from acetonitrile, tetrahydrofuran and 1,4-dioxane) and p-xylene solvate.     

Natural emergence

Emergence is analyzed by the principle of least action. The supreme law of nature describes diverse systems as actions that evolve from one state to another by consuming free energy in least time. As the system will either gain or lose quanta at the step of evolution, the systemic characteristics after the change of state cannot be reduced to those before the change. The change will invariably entail also a change in inter‐actions, which are flows of energy on paths that integrate ingredient systems to a synergistic system. New qualities will emerge along with opening interactions just as old ones will disappear along with ceasing interactions. The analysis of emergence as a natural process reveals that its irreducible and unpredictable nature does not result from complexity as such but because the natural process itself is molding the surroundings where it is evolving. © 2012 Wiley Periodicals, Inc. Complexity, 2012     

NMR and quantum chemical studies on association of 2,6-bis(acylamino)pyridines with selected imides and 2,2′-dipyridylamine

Abstract  

Association constants of 2,6-bis(alkylcarbonylamino)pyridines (alkyl = methyl or ethyl) and their perfluoroalkyl analogues with succin- and maleimide as well as with 2,2′-dipyridylamine (complementary DAD and ADA hydrogen bonding motifs are responsible for formation of the associates) have been determined by NMR titrations and quantum chemical calculations. Interactions of 2,6-bis(alkylcarbonylamino)pyridines with imides differ by character from these of perfluoroalkyl analogues. Such large difference was not observed for the 2,2′-dipyridylamine associates. Since fluorine atoms cause carbonylamino groups to be stronger hydrogen bond donors, perfluorinated species of this type were found to be more stable. Single crystal X-ray structures of 2,6-bis(trifluoromethylcarbonylamino)pyridine and 2,6-bis(pentafluoroethylcarbonylamino)pyridine have been also determined.