Enthalpies of 1,4-Dioxane, 1,2-Dimethoxyethane, and Ethylacetate Solvation in the Water–1-Propanol and Water–Glycerol Binary Mixtures

The enthalpies of 1,4-dioxane, 1,2-dimethoxyethane, and ethylacetate solution in binarymixtures of water with 1-propanol and glycerol were measured at 25°C using a precise isoperibol calorimeter. The enthalpies of the solute solvation were calculated and compared with the experimental data for other solutes. The results obtained were interpreted in terms of universal and specific solute solvation using parameters of a solvent polarity. It was found that the extreme shape of the curve _solv H° vs. X for ethylacetate in the mixtures of water with 1-propanol results from peculiarities of carbotylate-group solvation and appears to be not connected with the influence of alcohol microaggregates in the mixed solvent.     

Thermodynamics of solution of histidine

The enthalpies of solution of l-histidine in water at 288.15-318.15 K and 0.003-0.15 mol kg⁻¹ were measured. The enthalpies of solution were found to be independent of the solute molality up to ∼0.1 mol kg⁻¹. Standard enthalpies and heat capacities of solution were computed. Free energies and entropies of solution have been estimated in the temperature range studied using literature solubility data and the results of the present study. The temperature increase was found to result in a pronounced rise of the l-histidine solubility due to the significant increase of the TΔS values. The characteristic temperatures for the thermodynamic properties of histidine aqueous solutions were estimated.     

Support Vector Machine as an Efficient Framework for Stock Market Volatility Forecasting

Advantages and limitations of the existing models for practical forecasting of stock market volatility have been identified. Support vector machine (SVM) have been proposed as a complimentary volatility model that is capable to extract information from multiscale and high-dimensional market data. Presented results for SP500 index suggest that SVM can efficiently work with high-dimensional inputs to account for volatility long-memory and multiscale effects and is often superior to the main-stream volatility models. SVM-based framework for volatility forecasting is expected to be important in the development of the novel strategies for volatility trading, advanced risk management systems, and other applications dealing with multi-scale and high-dimensional market data.     

Feshbach resonance induced shock waves in Bose-Einstein condensates

We propose a method for generating shock waves in Bose-Einstein condensates by rapidly increasing the value of the nonlinear coefficient using Feshbach resonances. We show that in a cigar-shaped condensate there exist primary (transverse) and secondary (longitudinal) shock waves. We analyze how the shocks are generated in multidimensional scenarios and describe the related phenomenology.     

Interrelationship between ultimate mechanical properties of variously structured polyurethanes and poly(urethane urea)s and stretching rate thereof

The ultimate mechanical properties of polyurethane determine their possible applications under various conditions of mechanical action. The mechanical properties of nine polyurethane and polyurethane urea samples were investigated in a range of stretching rates 0.56÷0.002 s⁻¹. A part of experiments was performed at several temperature values under conditions of stepwise variable stretching rates. The interrelationship between rate dependence of strength–strain properties of polyurethane compositions and the structure thereof was ascertained. The influence of molecular structure’s variations, of physical network density and of segmented polyurethane and polyurethane urea morphology on said interrelationship was examined on samples subjected to large strain values. The structure of some samples was radically distorted by plasticizers oppositely influencing micro-phase segregation of soft and hard segments. Multiple kinds of dependency (direct, inverse, moderate and strong) of elastomers’ strength versus stretching rate were demonstrated. Produced data and ascertained regularities are useful to perceive reasons for diversity of mechanical behavior of polyurethane materials and to control properties thereof.     

Synthesis of 5-Cinnamoyl-3,4-dihydropyrimidine-2(1H)-ones

Two different approaches to the synthesis of 1-unsubstituted 5-cinnamoyl-3,4-dihydropyrimidine-2(1H)-ones have been developed. The first includes N(1)-protection of the starting 5-acetyl-3,4-dihydropyrimidine-2(1H)-one, further Claisen–Schmidt reaction, and cleavage of the protecting group. The second approach consists of one-pot condensation of urea, aldehyde, and cinnamoylacetone as dicarbonyl component. The 5-cinnamoylderivative synthesis starting from 5-acetyl-1,3-dialkyl-3,4-dihydropyrimidine-2(1H)-ones is also shown.     

Perception of interrupted speech: effects of dual-rate gating on the intelligibility of words and sentences

Perception of interrupted speech and the influence of speech materials and memory load were investigated using one or two concurrent square-wave gating functions. Sentences (Experiment 1) and random one-, three-, and five-word sequences (Experiment 2) were interrupted using either a primary gating rate alone (0.5-24 Hz) or a combined primary and faster secondary rate. The secondary rate interrupted only speech left intact after primary gating, reducing the original speech to 25%. In both experiments, intelligibility increased with primary rate, but varied with memory load and speech material (highest for sentences, lowest for five-word sequences). With dual-rate gating of sentences, intelligibility with fast secondary rates was superior to that with single rates and a 25% duty cycle, approaching that of single rates with a 50% duty cycle for some low and high rates. For dual-rate gating of words, the positive effect of fast secondary gating was smaller than for sentences, and the advantage of sentences over word-sequences was not obtained in many dual-rate conditions. These findings suggest that integration of interrupted speech fragments after gating depends on the duration of the gated speech interval and that sufficiently robust acoustic-phonetic word cues are needed to access higher-level contextual sentence information.