An evolutionary approach for bandwidth multicoloring problems

In this paper we consider some generalizations of the vertex coloring problem, where distance constraints are imposed between adjacent vertices (bandwidth coloring problem) and each vertex has to be colored with more than one color (bandwidth multicoloring problem). We propose an evolutionary metaheuristic approach for the first problem, combining an effective tabu search algorithm with population management procedures. The approach can be applied to the second problem as well, after a simple transformation. Computational results on instances from the literature show that the overall algorithm is able to produce high quality solutions in a reasonable amount of time, outperforming the most effective algorithms proposed for the bandwidth coloring problem, and improving the best known solution of many instances of the bandwidth multicoloring problem.     

Electrochemical behaviour of rosmanol 9-ethyl ether,a diterpene lactone antioxidant isolated from sage

The electrochemical behaviour and mechanism of the redox process of the natural antioxidant rosmanol 9-ethyl ether, isolated fromSaliva officinalis L., were studied. The cyclic voltammograms of rosmanol 9-ethyl ether (R9EE), at characteristic pH values, and the electrochemical parameters for all investigated pH values were measured. Three characteristic pH regions, each with different behaviour of R9EE, were identified. In regions of pH < 4 and pH > 5 only one anodic peak appeared, whereas in the solutions of pH 4–5 two anodic peaks could be noted. The overall oxidation mechanism at pH < 4 is an e.H.e.H. oxidation mechanism, which as a final product gives a quinonic molecule. The influence of pH on the second oxidation peak potential tends towards zero in accordance with the preceding dissociation of the one of phenolic groups, thus suggesting an e.e.H. mechanism at pH > 5. This means that at the pH values expected in plant cells, R9EE has an unexpected structure, making this substance a potent antioxidant. Electrochemical and spectrophotometric measurements enabled us to establish an extremely low pK _a value (4.35) for R9EE.     

Highly regioselective N-trans symmetrical diprotection of cyclen

A high yielding N-trans diprotection procedure for cyclen has been developed by using succinimide carbamate derivates of Boc and Cbz and chloroformate protecting groups.     

Structure and stability of ammonium-sulfate and guanidium-sulfate complex

Ab initio (HF/6-31G^** and B3LYP/6-31 + + G^**) methods have been used to study the stability and structure of complexes between CH₃SO⁻₃ and CH₃NH⁺₃ or C(NH₂)⁺₃. Results show that no hydrogen jump is involved in the complex formations, which is different from previous work studying complexes between CH₃COO⁻ and CH₃NH⁺₃. In addition, we have studied complexes between CH₃SO⁻₃ and HC(NH₂)⁺₃ or ⁺H₃NC(NH₂)₃, all of which have a cage structure.     

Ion-transport and diffusion coefficients of non-plasticised methacrylic-acrylic ion-selective membranes

The ion-transport behaviour of methacrylic-acrylic-based polymers for ion-selective electrode (ISE) membranes was investigated by a spectrophotometric method to determine the apparent diffusion coefficient. By observing the degree of deprotonation of the chromoionophore or chromogenic ionophore, the extent of penetration of cations into the polymer films was determined. The transport of the cations into the optode films depended on the stoichiometry of complexation by the ionophores. The apparent diffusion coefficients, estimated from the deprotonation data were of the order of 10⁻¹² to 10⁻¹¹ cm² s⁻¹. These values indicate that the apparent ion mobility in the methacrylic-acrylic ISE membranes is approximately a thousand times lower than that in plasticised PVC ISE membranes. For some ionophores, the value of the apparent diffusion coefficient could be modulated according to the ionophore content in the membrane and the data obtained for a calixarene containing membrane were tested against a model for facilitated diffusion with chained carriers. The data did not fit a model where intramolecular diffusion was limiting, but were consistent with a first-order rate-limiting mechanism involving an intermediate 1:2 complex between ion and ionophore. In this instance, the lowest values for D_app were thus not necessarily obtained for lowest ionophore loading and in the range examined, a trend of decreasing D_app with increasing ionophore was noted.     

Der Dreistoff: Uran-Bor-Kohlenstoff

Zusammenfassung Der Dreistoff: U-B-C wird mittels heißgepreßter Proben (etwa 60 Ansätze) röntgenographisch untersucht. Mit Ausnahme von U₂C₃ wird in diesen Legierungen das Bestehen aller übrigen bereits bekannten Zweistoffverbindungen bestätigt. Im Dreistoff-system tritt eine einzige ternäre Phase mit der ungefähren Formel UBC auf, die einen ausgedehnten homogenen Bereich besitzt. Diese Phase kristallisiert in der Raumgruppe D _2h ¹⁷ und leitet sich in ihrem Aufbau vom CrB- bzw. ZrSi₂-Typ her. Die Lage der Uranatome wird genau bestimmt (y _U=0,132 in 4c), Positionen von Bor und Kohlenstoff werden vorgeschlagen. Die ternäre Phase steht im Gleichgewicht mit: UC, UC₂, Kohlenstoff, UB₂ und UB₄.Mit 3 Abbildungen     

Revealing the Effect of Heat Treatment on the Spectral Pattern of Unifloral Honeys Using Aquaphotomics

In this study we aimed to investigate the effect of heat treatment on the spectral pattern of honey using near infrared spectroscopy (NIRS). For the research, sunflower, bastard indigo, and acacia honeys were collected from entrusted beekeepers. The honeys were not subject to any treatment before. Samples were treated at 40 °C, 60 °C, 80 °C, and 100 °C for 60, 120, 180, and 240 min. This resulted in 17 levels, including the untreated control samples. The 5-hydroxymethylfurfural (HMF) content of the honeys was determined using the Winkler method. NIRS spectra were recorded using a handheld instrument. Data analysis was performed using ANOVA for the HMF content and multivariate analysis for the NIRS data. For the latter, PCA, PCA-LDA, and PLSR models were built (using the 1300–1600 nm spectral range) and the wavelengths presenting the greatest change induced by the perturbations of temperature and time intervals were collected systematically, based on the difference spectra and the weights of the models. The most contributing wavelengths were used to visualize the spectral pattern changes on the aquagrams in the specific water matrix coordinates. Our results showed that the heat treatment highly contributed to the formation of free or less bonded water, however, the changes in the spectral pattern highly depended on the crystallization phase and the honey type.     

On the Small-Scale Mass Concentration of Modes

Let be commuting, jointly-elliptic, -pseudodifferential operators on a compact manifold, X, of dimension n≥d. Suppose γ is the ω-limit set of the bicharacteristic flow of the classical Hamiltonian, p ₁, restricted to the variety, . We discuss the corresponding concentration of mass as for a subsequence of joint eigenfunctions of the P _j 's with eigenvalues sufficiently close to . Received: 1 October 1998 / Accepted: 1 April 1999