Remote stereocontrol by the sulfinyl group: Mukaiyama aldol reactions of (S)-2-[2-(p-tolylsulfinyl)phenyl]acetaldehyde in the asymmetric synthesis of β-hydroxyacids and 1,3-diols

(S)-2-[2-(p-Tolylsulfinyl)phenyl]acetaldehyde reacts with different O-silylated ketenethioacetals in the presence of Yb(OTf)₃ yielding β-hydroxythioesters in high yields and diastereoselectivities. The obtained compounds were readily transformed into β-hydroxyacids and their corresponding diols. These Mukaiyama aldol reactions are a direct evidence of the ability of the sulfinyl group to control 1,5- and 1,6-asymmetric induction processes.     

A study of formation of solid ionic conductors in the mixed system (CdI2)b[(Ag2O)·(CrO3)]100-b (20≤b≤80)

Using Wagner's polarization technique and EMF method the joinic and silver ionic transport number measurements of various compositions of the mixed system CdI₂-Ag₂O-CrO₃ have been made. The presence of AgI in these materials has been inferred from the typical β → α phase transition of AgI, which is characterized by an endothermic peak at around 420 K in the DSC traces of these specimens. While the structural analysis performed by means of powder X-ray diffraction has revealed the formation of ionic phases involving polycrystalline compounds, the Fourier transform infrared (FTIR) spectroscopic results have indicated the presence of ionic species thus confirming the ionic nature of the products. The complex impedance studies carried out in the frequency range 20 Hz - 1 MHz and over the temperature range 294 – 442 K have revealed that the best conducting composition, namely 55%(CdI₂) – 45%(Ag₂O·CrO₃), would exhibit a silver ionic conductivity of 1.3×10⁻⁵Scm⁻¹ at 294 K.     

Observation of dielectronic satellites in the K-spectrum of argon ions in plasma produced by femtosecond laser pulses

The satellite structure of 1s2p ^1,3 P ₁-1s ²¹ S ₀ lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters.     

Coherent Type-B e + e- Pair Production by Photons in a Crystal

An overview of theoretical and experimental studies of the coherent type-B e ⁺ e-pair production by photons in aligned crystals performed at Nuclear Physics Institute at Tomsk Polytechnic University is given.     

The frequency scale of speech intonation.

In intonation research, prominence-lending pitch movements have either been described on a linear or on a logarithmic frequency scale. An experiment has been carried out to check whether pitch movements in speech intonation are perceived on one of these two scales or on a psychoacoustic scale representing the frequency selectivity of the auditory system. This last scale is intermediary between the other two scales. Subjects matched the excursion size of prominence-lending pitch movements in utterances resynthesized in different pitch registers. Their task was to adjust the excursion size in a comparison stimulus in such a way that it lent equal prominence to the corresponding syllable in a fixed test stimulus. The comparison stimulus and the test stimulus had pitches running parallel on either the logarithmic frequency scale, the psychoacoustic scale, or the linear frequency scale. In one-half of the experimental sessions, the test stimulus was presented in the low register, while the comparison stimulus was presented in the high register, and, conversely, for the other half of the sessions. The result is that, in all cases, stimuli are matched in such a way that the average excursion sizes in different registers are equal on the psychoacoustic scale.     

Diffusion from sessile droplets through membranes

We analyze diffusion from a periodic array of hemispherical droplets through a membrane. We find that the multiple sources do not interact strongly, even when the droplets are closely spaced, so that the flux through the membrane appears nearly additive.