Неохлаждаемые фотодиоды для регистрации импульсного инфракрасного излучения в спектральном диапазоне 0.9-1.8 мкм

Uncooled GaSb/GaAlAsSb photodiodes for detecting pulsed infrared radiation in the spectral range of 0.9-1.8 µm have been developed. Active GaSb layer was grown using lead as a neutral solvent in order to reduce the concentration of natural acceptors. The capacity of the photodiodes with a diameter of photosensitive area of 300 µm was 115−135 pF with no bias and 62−70 pF at U=−1.5 V. The photodiode speed of response measured using an InGaAsP/InP laser with a wavelength of 1.55 µm reached tau=42−60 ns in the photovoltaic mode. It is shown experimentally that the photodiodes can be used without cooling to detect the pulsed radiation of lasers and LEDs in the near-infrared region of the spectrum.

Women show enhanced attractiveness ratings and neural processing of male faces associated with male chemosensory signals

There is growing evidence that humans use olfactory chemosensory signals for social communication, but their role in affective associative learning is largely unknown. To examine this, women implicitly learned face-odor associations by pairing different neutral male faces with either a male chemosignal presumably involved in human mating behavior (dissolved Δ4,16-androstadien-3-one, “AND”), a pleasant smell (dissolved vanillin) or the neutral solvent alone. After learning, women rated faces previously paired with AND or vanillin as more attractive than faces paired with solvent, even though they were unable to identify the contingency of face-odor pairings above chance level. On a neurophysiological level, both AND- and vanillin-associated faces evoked stronger magnetoencephalographic correlates of enhanced emotional attention than solvent-associated faces at early (<120 ms) and mid-latency (140-270 ms) processing stages. This study stresses the role of AND as a human chemosignal in implicit social communication and demonstrates its effectiveness in modulating emotional learning.

INFLUENCE OF SODIUM HYDROXIDE ADDITIVES ON HYDROGENIZATION KINETICS OF 4-NITRO-2'-HYDROXY-5'-METYLAZOBENZENE ON SKELETAL NICKEL IN AQUEOUS SOLUTION OF 2-PROPANOL

The elucidation of the sequence of transformations in compounds containing several reactive groups and the development of approaches to controlling the selectivity of the processes with their participation is of interest both from the theoretical and practical points of view. The article is devoted to the analysis of the kinetics of hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene in aqueous solution of 2-propanol with addition of sodium hydroxide on skeletal nickel at different initial amounts of the starting compound. An increase in the initial amount of 4-nitro-2'-hydroxy-5'-methylazobenzene leads to an increase in the rate of conversion of the nitro group in the starting compound and to a decrease in the rate of conversion of the azo-group. The effect of the introduced sodium hydroxide in the neutral solvent 2-propanol-water on the rate of conversion of the nitro and azo-groups to 4-nitro-2'-hydroxy-5'-methylazobenzene is consistent with the nature of the rate changes for the hydrogenation of individual compounds containing nitro and azo-groups, in the quality of which 4-nitroaniline and 4-amino-2'-hydroxy-5'-methylazobenzene were chosen. The results obtained do not contradict the notion of a parallel-sequential scheme of 4-nitro-2'-hydroxy-5'-methylazobenzene transformations. One of the directions involves the conversion of 4-nitro-2'-hydroxy-5'-methylazobenzene due to the hydrogenation of the azo-group to 4-nitroaniline and PC, and the second one is the conversion of 4-nitro-2'-hydroxy-5'-methylazobenzene through 4-amino-2'-hydroxy-5'-methylazobenzene due to the reduction of the nitro group. By the end of the reaction, all the intermediate compounds are restored to PC and 1,4-phenylenediamine. When sodium hydroxide is introduced into the neutral solvent 2-propanol-water, the effect of the direction providing the formation of 4-amino-2'-hydroxy-5'-methylazobenzene to the overall reaction rate increases. It was experimentally established that the amount of 4-amino-2'-hydroxy-5'-methylazobenzene during the hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene in the presence of sodium hydroxide increases by 15%, on the contrary, the amount of 4-nitroaniline decreases by 4 % in comparison with the neutral solvent.

Magnetic field control of the ordering of two-component suspension of hard rods

The Onsager theory of hard rod dispersion in a neutral solvent is extended to a case of two-component dispersion consisting of both non-magnetic and magnetic rods. It was found that the alignment of magneto-sensitive dispersion component by a magnetic field leads to the alignment of non-magnetic component in the dispersion and to an elimination of the isotropic phase. This effect is significant even at low relative concentrations of magnetic rods and leads to a magnetically induced anisotropy in a non-magnetic dispersion of rods mixed with the magnetic ones.