On top-down splaying

The splay tree is a self-adjusting binary search tree which has a good amortized performance. This paper studies some properties of top-down splay trees. Different ways to charge for the primitive operations of top-down splaying are discussed. We also give some empirical results concerning the behaviour of different top-down restructuring algorithms.This work was supported by the Academy of Finland.     

Monitoring of yeast fermentation by ion mobility spectrometry measurement and data visualisation with Self-Organizing Maps

Ion mobility spectrometry (IMS) measurement combined with unsupervised neurocomputing is considered as a new potential method for on-line monitoring of fermentation and other processes producing volatile compounds that involve micro-organisms. This was demonstrated in a model system in which a strain of brewer’s yeast (Saccharomyces cerevisiae) was cultivated in a bench-top fermenter. Five phases of yeast growth could be detected from measurements of the exhaust gases from the fermenter, as indicated by the changes in ion mobility spectra analysed by computational methods.The data were first processed using the Self-Organizing Map (SOM) algorithm, the results showing that the phases of fermentation can be detected and identified. The cultivations were also shown by Sammon’s mapping to be comparable to a certain level of accuracy. Contaminated cultivation could be detected by its distinctive ion mobility spectrometry profile.     

Simulation of13C NMR chemical shifts for polychlorinated and polybrominated oxybenzenes with two-particle increment scheme

A two-particle system of OY-Cl and OY-Br mixed increments for predicting¹³C NMR chemical shifts of polyhalogenated polyoxybenzenes has been developed. It has been found that only theortho- and para-interactions of the OY and Hal substituents contribute significantly to the¹³C chemical shifts and that theortho-effects of the OY located between Ha1 and H and those of the OY located between two Ha1 atoms are different. Additional effects are due to solvating solvents. The increment scheme is predictive over the whole class of compounds under consideration and may be realized on personal computers.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 617–624, April, 1994.     

Gas chromatographic optimization studies on the side chain and ring regioisomers of methylenedioxymethamphetamine

Gas chromatographic (GC) optimization studies are conducted for the 10 methylenedioxyphenethylamine regioisomeric substances related to the drug of abuse 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy). These 10 compounds, having the same molecular weight and equivalent major mass spectral fragments, are not completely resolved using typical GC-mass spectrometry screening methods for illicit drugs. MDMA coelutes with at least one nondrug regioisomer under standard drug screening conditions. Separation of the 10 regioisomers is studied using stationary phases of varying polarities. Resolution optimization shows that very slow program rates give the best separation for the nonpolar stationary phases, requiring analysis times of as much as 85 min. Narrow-bore columns containing the same nonpolar stationary phases improve the analysis time to approximately 29 min. The polar stationary phase DB-35MS allows high-temperature programming rates, yielding complete resolution of all 10 compounds in less than 7 min. Temperature program optimization studies on the DB-35MS phase allow the separation time to be reduced to approximately 4.5 min.     

Scaled AMO calculations on the hydrogen molecule II. The 1s σ 2p σ 1∑ state

A scaled version of the AMO method is applied to the 1sσ2pσ ¹∑ state of the hydrogen molecule. A method to extend the domain of the mixing parameter λ to the whole complex plane is described and applied in the present calculation. All the parameters introduced have been varied completely. A considerable improvement in the computed energy values is found for large internuclear separations R. The comparison between our potential energy curve and the accurate curve calcualted by Kolos and Wolniewicz is studied and, for example, for R = 12 a.u. the energy difference is only 18% of that for R = 2.43 a.u. The equilibrium separation is found to be 2.140 a.u. in poor agreement with 2.429 a.u. obtained by the previously mentioned authors. In the separated atom limit, the state under consideration does not dissociate into H⁺ + H^?, although the ionic character of the wave function is dominating in the region 3 ≦ R ≦ 8 a.u. The connections with earlier calculations and methods, especially the scaled version of the MO –LCAO approximation, are also pointed out and discussed.     

Association of bound states of the coulomb potential with resonances of the coulomb potential perturbed by a barrier

In the present article we show how the bound states of the Coulomb potential may be associated with resonances that occur when this potential is perturbed by a barrier potential. The main idea is to trace the bound states on successive switching on of the barrier perturbation. It is found that those bound states that are localized inside the barrier are highly sensitive to variation with respect to the barrier height, whereas those that are localized outside are less sensitive. However, there are certain intervals for the barrier height when the role of being “a state localized inside the barrier” is shifted from one bound state to another. The result can be pictured as a “relay race,” where the “deliveries of the baton” are carried out over corresponding avoided crossings. The baton is ultimately handed over to a shape-type resonance state.     

Reaction of ruthenium carbonylcarbide cluster Ru6C(CO)17 with nickelocene and pentamethylcyclopentadiene

The reaction of cluster Ru₆C(CO)₁₇ (1) with nickelocene is studied. Five CO ligands rather than a metal-ligand crown are substituted for two cyclopentadienyl groups to give a new complex Ru₆C(⁵-Cp)₂(CO)₁₂ (2). The reaction of cluster1 with entamethylcyclopentadiene leads to new complex Ru₆C(-¹⁵-CH₂C₅Me₄)(CO)₁₄ (3) containing the cr-bond CH₂-Ru, along with an ⁵-coordinated cyclopentadienyl ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1171–1172, June, 1995.     

The temperature-dependent red-shift of the visible absorption spectra of crystal violet in alcohol solutions

The visible absorption spectrum of the triphenylmethane dye, crystal violet, in various alcohol solutions at several temperatures has been recorded and subsequently analyzed by computer fitting. The observed spectral changes do not sustain either the earlier temperature-dependent absorption results of Lewis and co-workers or the concept of two ground-state species in equilibrium.     

Co-eluent effect in partition chromatography. Rhamnose-xylose separation with strong and weak cation-exchangers in aqueous ethanol

The effect of ethanol in aqueous eluent on the chromatographic separation was studied at 298 K. Two sugars, L-rhamnose and D-xylose, were separated by using strong and weak cation-exchangers as a stationary phase. The ionic form of the resins was Na+ or Ca2+. The separations were carried out with sugar feed concentrations up to 35 wt% and with both low (about 1%) and high (about 10%) feed volume to bed volume ratios. The separation of the sugars was improved by adding ethanol into the eluent. The separation was also significantly enhanced when the weak cation-exchangers with the greatest affinity for water were used instead of strong cation-exchangers as a separation medium for the sugars having different hydrophilicities. The experimental data were successfully explained with a rate-based column model, which accounted for the volume changes of the stationary phase. A thermodynamic sorption model was utilized in column calculations.     

Comparison of polydimethyl siloxane stationary phases with 5% and 50% phenyl substitution for the separation of organophosphorus and organonitrogen pesticides under optimized gas chromatographic conditions

The CGC analysis of 25 organophosphorus and organonitrogen pesticides was optimized on two different stationary phases, namely a 5% diphenyl dimethyl silicone (SE-54 type) and a 50% diphenyl dimethyl silicone (OV-17 type) by selecting the best temperature program conditions, using computer simulation.