Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Quantum theory of light and noise polarization in nonlinear optics

We present a consistent quantum theory of the electromagnetic field in nonlinearly responding causal media, with special emphasis on $\chi^{(2)}$ media. Starting from QED in linearly responding causal media, we develop a method to construct the nonlinear Hamiltonian expressed in terms of the complex nonlinear susceptibility in a quantum mechanically consistent way. In particular we show that the method yields the nonlinear noise polarization, which together with the linear one is responsible for intrinsic quantum decoherence.Comment: 4 pages, no figure

Особенности вызванной активности мозга девушек-носительниц различных генотипов по маркеру MAOA -uVNTR при оценке эмоционально окрашенных сцен

Studying the correlation between the characteristics of the structure of genes and the parameters of the evoked brain activity is a relevant problem of modern research. It is known that the MAOA gene, which influences the concentration of such neurotransmitters-monoamines as dopamine, serotonin, and norepinephrine, is associated with different psychological characteristics. However, very little is known about the association of this gene with psycho-physiological indices. The purpose of the present study was to investigate the characteristics of amplitude and spatial-temporal characteristics of the evoked brain activity in girls (at the age from 18 to 24) who were carriers of different MAOA genotypes. According to the results of genotyping, the participants (61 persons) were divided into two groups: with the high-activity and heterozygous MAOA -uVNTR genotypes. In the study the authorsrecorded visual evoked potentials in 64 derivations. Emotionally charged and neutral images were stimuli in the study.The paper describes modern views on the correlation between MAOA genotypes and the features of cortico-limbic interaction. The results of the study showed that the heterozygous genotypes were apparently associated with lesser efficiency of regulating functions. To activate neural systems of the frontal divisions the female carriers of the heterozygous genotypes of MAOA needed the stimuli with a high arousal effect; this can be connected with a less efficient process of selecting relevant stimuli. At the same time, the high-activity MAOA genotypes in women are probably associated with high efficiency of controlling functions (attention, planning, control) of the prefrontal cortex when assessing emotionally charged images, which is accompanied by the intensity of activation of these brain structures.Изучение связей между особенностями строения генов и параметрами вызванной активности мозга – актуальная тема современных исследований. Известно, что ген MAOA, оказывающий влияние на концентрацию таких нейромедиаторов-моноаминов, как дофамин, серотонин и норадреналин, ассоциирован с различными психологическими характеристиками. Однако исследовательских работ, посвященных изучению ассоциации данного гена с психофизиологическими показателями, на сегодняшний день недостаточно. Целью данного исследования явилось изучение особенностей амплитудных и пространственно-временных характеристик вызванной активности мозга девушек 18–24 лет, являющихся обладательницами различных генотипов MAOA. По результатам генотипирования участницы (61 человек) были разделены на две группы: с высокоактивными и гетерозиготными генотипами по маркеру MAOA -uVNTR. В ходе исследования была проведена регистрация зрительных вызванных потенциалов в 64 отведениях. В качестве стимулов выступили эмоционально окрашенные и нейтральные изображения. В работе описаны современные представления о связи генотипов MAOA с особенностями кортико-лимбического взаимодействия. По результатам собственного исследования получено, что гетерозиготные генотипы, вероятно, связаны с меньшей эффективностью регуляторных функций. Для активации нейронных систем лобных отделов девушкам-носительницам гетерозиготных генотипов MAOA необходимо воздействие раздражителей, обладающих высоким arousal-эффектом, что может быть связано с менее эффективным процессом отбора релевантных стимулов. В то же время, высокоактивные генотипы MAOA у женщин, вероятно, ассоциированы с высокой эффективностью управляющих функций (внимание, планирование, контроль), выполняемых префронтальными отделами коры мозга при оценке эмоционально окрашенных изображений, что сопровождается достаточной интенсивностью активации данных мозговых структур

The role of Auger recombination in the temperature-dependent output characteristics (T0=∞)(T0=∞) of pp-doped 1.3 μm quantum dot lasers

Temperature invariant output slope efficiency and threshold current (T0=∞)(T0=∞) in the temperature range of 5–75 °C have been measured for 1.3 μm pp-doped self-organized quantum dot lasers. Similar undoped quantum dot lasers exhibit T0=69 KT0=69 K in the same temperature range. A self-consistent model has been employed to calculate the various radiative and nonradiative current components in pp-doped and undoped lasers and to analyze the measured data. It is observed that Auger recombination in the dots plays an important role in determining the threshold current of the pp-doped lasers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71264/2/APPLAB-85-22-5164-1.pd

Narrow ridge waveguide high power single mode 1.3-μm InAs/InGaAs ten-layer quantum dot lasers

Ten-layer InAs/In0.15Ga0.85As quantum dot (QD) laser structures have been grown using molecular beam epitaxy (MBE) on GaAs (001) substrate. Using the pulsed anodic oxidation technique, narrow (2 μm) ridge waveguide (RWG) InAs QD lasers have been fabricated. Under continuous wave operation, the InAs QD laser (2 × 2,000 μm2) delivered total output power of up to 272.6 mW at 10 °C at 1.3 μm. Under pulsed operation, where the device heating is greatly minimized, the InAs QD laser (2 × 2,000 μm2) delivered extremely high output power (both facets) of up to 1.22 W at 20 °C, at high external differential quantum efficiency of 96%. Far field pattern measurement of the 2-μm RWG InAs QD lasers showed single lateral mode operation

Submonolayer Quantum Dots for High Speed Surface Emitting Lasers

We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs using ultrathin spacer layers. Vertically correlated, tilted or anticorrelated arrangements of the SML islands are realized and allow QD strain and wavefunction engineering. Respectively, both TE and TM polarizations of the luminescence can be achieved in the edge-emission using the same constituting materials. SML QDs provide ultrahigh modal gain, reduced temperature depletion and gain saturation effects when used in active media in laser diodes. Temperature robustness up to 100 °C for 0.98 μm range vertical-cavity surface-emitting lasers (VCSELs) is realized in the continuous wave regime. An open eye 20 Gb/s operation with bit error rates better than 10−12has been achieved in a temperature range 25–85 °Cwithout current adjustment. Relaxation oscillations up to ∼30 GHz have been realized indicating feasibility of 40 Gb/s signal transmission

Investigation of Semiconductor Quantum Dots for Waveguide Electroabsorption Modulator

In this work, we investigated the use of 10-layer InAs quantum dot (QD) as active region of an electroabsorption modulator (EAM). The QD-EAM is a p-i-n ridge waveguide structure with intrinsic layer thickness of 0.4 μm, width of 10 μm, and length of 1.0 mm. Photocurrent measurement reveals a Stark shift of ~5 meV (~7 nm) at reverse bias of 3 V (75 kV/cm) and broadening of the resonance peak due to field ionization of electrons and holes was observed for E-field larger than 25 kV/cm. Investigation at wavelength range of 1,300–1320 nm reveals that the largest absorption change occurs at 1317 nm. Optical transmission measurement at this wavelength shows insertion loss of ~8 dB, and extinction ratio of ~5 dB at reverse bias of 5 V. Consequently, methods to improve the performance of the QD-EAM are proposed. We believe that QDs are promising for EAM and the performance of QD-EAM will improve with increasing research efforts

ASSOTIATION OF COMBINATIONS OF COMT AND DRD4 GENOTYPES WITH EMOTIONAL AND PERSONAL CHARACTERISTICS IN YOUTH

The article presents the results of a theoretical and empirical study of the relationship between the combinations of genotypes of catechol-O-methyltransferase and the fourth type of dopamine receptor genes with such emotional and personal characteristics of young people as extraversion, goodwill, conscientiousness, neuroticism, openness to experience (Big Five), level of emotional intelligence, empathy, alexithymia. The study of the genetic basis of these characteristics is of particular interest due to their close relationship with the success of communications and socio-psychological adaptation of a person.В статье представлены результаты теоретического и эмпирического исследования связи сочетаний генотипов генов катехол-О-метилтрансферазы и рецептора дофамина четвертого типа с такими эмоционально-личностными особенностями молодежи, как экстраверсия, доброжелательность, добросовестность, нейротизм, открытость опыту (большая пятерка), уровень эмоционального интеллекта, эмпатии, алекситимии. Исследование генетического базиса перечисленных характеристик представляет особенный интерес ввиду их тесной связи с успешностью коммуникаций и социально-психологической адаптации человека

Nonlinear optics and saturation behavior of quantum dot samples under continuous wave driving

The nonlinear optical response of self-assembled quantum dots is relevant to the application of quantum dot based devices in nonlinear optics, all-optical switching, slow light and self-organization. Theoretical investigations are based on numerical simulations of a spatially and spectrally resolved rate equation model, which takes into account the strong coupling of the quantum dots to the carrier reservoir created by the wetting layer states. The complex dielectric susceptibility of the ground state is obtained. The saturation is shown to follow a behavior in between the one for a dominantly homogeneously and inhomogeneously broadened medium. Approaches to extract the nonlinear refractive index change by fringe shifts in a cavity or self-lensing are discussed. Experimental work on saturation characteristic of InGa/GaAs quantum dots close to the telecommunication O-band (1.24-1.28 mm) and of InAlAs/GaAlAs quantum dots at 780 nm is described and the first demonstration of the cw saturation of absorption in room temperature quantum dot samples is discussed in detail