Analysis of Static Simulated Annealing Algorithms

Generalized hill climbing (GHC) algorithms provide a framework for modeling local search algorithms to address intractable discrete optimization problems. This paper introduces a measure for determining the expected number of iterations to visit a predetermined objective function level, given that an inferior objective function level has been reached in a finite number of iterations. A variation of simulated annealing (SA), termed static simulated annealing (S²A), is analyzed using this measure. S²A uses a fixed cooling schedule during the algorithm execution. Though S²A is probably nonconvergent, its finite-time performance can be assessed using the finite-time performance measure defined in this paper.     

Performance Analysis of Cyclical Simulated Annealing Algorithms

Generalized hill climbing (GHC) algorithms provide a framework for modeling local search algorithms for addressing intractable discrete optimization problems. Measures for assessing the finite-time performance of GHC algorithms have been developed using this framework, including the expected number of iterations to visit a predetermined objective function value level. This paper analyzes how the expected number of iterations to visit a predetermined objective function value level can be estimated for cyclical simulated annealing. Cyclical simulated annealing uses a cooling schedule that cycles through a set of temperature values. Computational results with traveling salesman problem instances taken from TSPLIB show how the expected number of iterations to visit solutions with predetermined objective function levels can be estimated for cyclical simulated annealing.AMS 2000 Subject Classification 90-08 Computational Methods: Local Search, 90C59 Heuristics: Simulated Annealing     

Preparation of a new chiral acridino-18-crown-6 ether-based stationary phase for enantioseparation of racemic protonated primary aralkyl amines

Starting from commercially available and relatively cheap chemicals first enantiopure dimethyl-substituted monoaza-18-crown-6 ether (R,R)-21 containing a diphenylamine unit was prepared, which was then transformed to dimethyl-substituted acridino-18-crown-6 ligand (R,R)-19 having an N-allyl-carbamoyl linker by several steps. The terminal double bond of the latter made possible to attach (R,R)-19 to γ-mercaptopropyl-functionalized spherical HPLC quality silica gel obtaining a new chiral stationary phase (R,R)-CSP-37. Based on electronic circular dichroism (ECD) studies the N-allyl-carbamoyl group attached to the acridine ring of the chiral host (R,R)-19 does weaken exciton interaction between the host and guest molecules, but does not destroy the discriminating power of the chiral host. An HPLC column filled with (R,R)-CSP-37 was tested for the enantioseparation of racemic 1-(1-naphthyl)- and 1-(2-naphthyl)ethylamine hydrogenperchlorates using isocratic conditions.     

Demonstration of a protein with enhanced resistance to proteinase K in transmissible cytopathic condition elicited by cell-free lysate of free-living ameba Naegleria gruberi

The cell-free lysate of free-living amebae Naegleria gruberi and Naegleria fowleri were reported to elicit cytopathic effect in various cell lines that could be indefinitely transmitted by the culture media. The causative agent showed sensitivity to treatments detrimental to proteins while resisted exposures damaging to nucleic acids. Here we demonstrate that subsequent to exposure to N. gruberi lysate mild digestion with proteinase K reveals the presence of a protein band in HeLa cells absent from control cell lines. Though the small quantity of this protein with enhanced resistance to proteinase K relative to the total protein content of the sample has proved to date insufficient for its purification, we suppose that it is a human cellular protein that assumed altered conformation in a prion-like fashion. The conformational conversion could have been trigerred by an ameba protein in the lysate. In addition, we showed that HeLa cells treated with N. gruberi lysate display elevated cathepsin B activity which is assumed to be a secondary response to the accumulation of the proteinase K-resistant protein. We propose that a number of degenerative sequelae following previous microbial infections in mammals could have a similar pathomechanism. Moreover, epidemiological data strongly suggest that natural prion disease in sheep, goat and cervids may also have an etiology linked to prior infection/colonization with a microbe, as it had already been proposed by one of us.     

New Types of Telechelic Polyisobutylenes, 1

Summary: A new, simple, and effective synthetic method for the preparation of glucose‐terminated polyisobutylenes starting from the corresponding hydroxyl‐terminated polymers is reported. Detailed NMR and matrix‐assisted laser desorption/ionization mass spectrometric (MALDI‐TOF MS) investigations showed the exclusive presence of bis(glucopyranosyl) polyisobutylene. Dynamic light scattering (DLS) investigations of this polymer in solution in both tetrahydrofuran and water showed that microphase separation takes place by the formation of micelles and/or vesicles.

Representative structure of the glucose‐terminated polyisobutylenes synthesized here.     

Substitution and elimination reactions in aluminum oxide: 1-alpha- and 1-beta-benzoyloxy-delta-2-cholestene and 3-beta-chlor-delta-1-cholestene

The formerly discribed [1] unknown substance CHT 208, which was obtained as side product when 3β-benzoyloxy-Δ¹-cholestene ( 3 ) was treated with ‘neutral’ activated alumina in an unpolar solvent, has been recognized as consisting of ca. 67% 3β-hydroxy-Δ¹-cholestene ( 6 ) and of ca. 33% 3β-hydroxy-Δ¹-cholestene ( 4 ) (molecular compound 2:1). Analogous treatment of 3β-chloro-Δ¹-cholestene ( 5 ) with alumina yielded the same mixture of the allylic alcohols 4 and 6 as substitution products and of Δ^1,3-cholestadiene ( 2 ) as elimination product in equal amounts.     

Effect of nanosizing on lattice and magnon modes of hematite

Broadening of Raman lines and a decrease of frequencies relative to the bulk material are observed for the lattice modes of nanoparticles of the hematite phase of Fe₂O₃. The magnon mode frequency is observed to shift up with reduced particle size in contrast to the lattice modes. The effects are suggested to be a result of phonon confinement and represent the first observation of phonon confinement effects on magnon modes. The Fe₂O₃ nanoparticles are produced by laser decomposition of Fe₃O₄ nanoparticles. X-ray diffraction and Raman frequency shifts indicate the Fe₂O₃ nanoparticles are smaller than the parent Fe₃O₄ nanoparticles.     

High-performance liquid chromatographic enantioseparation of cyclic β-aminohydroxamic acids on zwitterionic chiral stationary phases based on Cinchona alkaloids

Cyclic β-aminohydroxamic acid enantiomer pairs were stereoselectively separated by high-performance liquid chromatography on the recently developed Cinchona alkaloid-based zwitterionic chiral stationary phases Chiralpak ZWIX(+)™, ZWIX(−)™, ZWIX(+A) and ZWIX(−A). The results of variation of the applied chromatographic conditions, such as the bulk solvent composition, the concentrations and ratio of the acid and base additives, the presence of water as mobile phase additive and the counter-ion concentration furnished a better understanding of the retention mechanism. A thermodynamic study in the temperature range 5–50 °C revealed enthalpy-controlled enantiodiscrimination in all cases. The structure–selectivity relationships clearly indicated the importance of the strereochemistry of the functional groups. From an enantiorecognition aspect, the diexo position of the functional groups always proved more favorable than the diendo position. The elution sequence was determined in all cases and was found to reversed when ZWIX(+)™ was changed to ZWIX(−)™ or ZWIX(+A) to ZWIX(−A).