266 research outputs found
Zaryadye Park, Glass Grid Shell Roof
This paper will describe the design, detailing, testing and construction of the structural glass beams which make up the load bearing grid shell structure of the newly built Zaryadye Park in Moscow, Russia. The canopy structure is situated short distance from Red Square and the Kremlin. Structural glass beams, 72 in total, are connected into the main undulating steel grid shell structure which measures approximately 120m long and 60m wide. The beams themselves vary in length according to the geometry but are generally 3m long, 0.2m deep. The beams meet each other and the main steel structure at bespoke stainless steel nodes, and are topped by triangular glass roof panels. The glass beams were designed to accommodate Moscow’s extreme weather conditions, with drifted snow loads of up to 350 kg/m2. Differential movement of the main structure was another challenge for the design team, and required sophisticated linear analysis with over 150 load combinations. The resulting movements called for further development of the nodal connections and non-linear analysis of their performance. Due to a lack of legislation covering structural glass in Russia a so called ‘Special Technical Standard’ was required. This document was written with significant input from us and covers the technical aspects of glass and its performance. A full scale mock-up of one roof panel, complete with beams and node connections, was constructed and tested to gain approvals from the authorities. Zaryadye Park is Moscow’s first new major landmark in 50 years and was opened on the 9th of September in time for the City Day celebrations
Decision Support System for Urbanization of the Northern Part of the Volga-Akhtuba Floodplain (Russia) on the Basis of Interdisciplinary Computer Modeling
There is a computer decision support system (CDSS) for urbanization of the
northern part of the Volga-Akhtuba floodplain. This system includes subsystems
of cognitive and game-theoretic analysis, geoinformation and hydrodynamic
simulations. The paper presents the cognitive graph, two-level and three-level
models of hierarchical games for the cases of uncontrolled and controlled
development of the problem situation. We described the quantitative analysis of
the effects of different strategies for the spatial distribution of the
urbanized territories. For this reason we conducted the territory zoning
according to the level of negative consequences of urbanization for various
agents. In addition, we found an analytical solution for games with the linear
dependence of the average flooded area on the urbanized area. We numerically
computed a game equilibrium for dependences derived from the imitational
geoinformation and hydrodynamic modeling of flooding. As the result, we showed
that the transition to the three-level management system and the implementation
of an optimal urbanization strategy minimize its negative consequences.Comment: 14 pages, 5 figures; Conference: Creativity in Intelligent
Technologies and Data Science. CIT&DS 201
Validation Tests of the W2020 Energy Levels of Water Vapor
A decade ago, a task group of the International Union of Pure and Applied Chemistry performed an exhaustive collection and review of measured transitions, applied the MARVEL procedure, and derived recommended empirical energy levels for nine major water isotopologues. Very recently, using an improved methodology, the sets of empirical energy levels of H216O, H218O and H217O were updated, leading to the so-called W2020 energy levels and transition wavenumbers [Furtenbacher et al. J. Phys. Chem. Ref. Data 49 (2020) 043103; 10.1063/5.0030680]. Here we present validation tests of the W2020 line list of H216O against spectra recorded by cavity ring down spectroscopy (CRDS) referenced to a frequency comb (FC), newly obtained in the 8040-8630 cm−1 region. The recorded spectra are found in excellent agreement with previous high-quality studies available in the literature. While these literature sources were all incorporated in the transition database used to derive the W2020 energy levels, the direct superposition of the FC-CRDS spectra to the W2020 line list of H216O shows a number of large disagreements. Cases where deviations largely exceed the W2020 claimed uncertainty on the transition frequencies are noted. In the considered spectral region, the resulting W2020 list is thus less accurate than some of the published original sources used to derive the W2020 energy levels. We conclude that the sophisticated global procedure and algorithm elaborated to identify and adequately weight inaccurate line positions among the large W2020 transition database do not always prevent less accurate data from “spoiling” higher quality data sources. The W2020 list of H216O is also compared to newly recorded CRDS spectra in the 12970–13200 cm−1 region (corresponding to the region of the A-band of O2), where previous observations were very scarce. As in the previous region, substantial position deviations are evidenced, and in many cases, the W2020 error bars appear to be strongly underestimated. © 2021 Elsevier LtdThe support of the CNRS (France) in the frame of International Research Project SAMIA is acknowledged. SNM activity was also partly supported in the frame of the Russian Science Foundation, Grant No. 18-11-00024-Π. CRDS measurements near 760 nm were performed at IAO-Tomsk and funded by RFBR project 20-32-70054
Water Vapor Absorption in the Region of the Oxygen A-Band Near 760 nm
The oxygen A-band near 760 nm is used to determine the air-mass along the line of sight from ground or space borne atmospheric spectra. This band is located in a spectral region of very weak absorption of water vapor. The increased requirements on the determination of the air columns make suitable to accurately characterize water absorption spectrum in the region. In the present work, we use a cavity ring down spectrometer newly developed in Tomsk, to measure with unprecedented sensitivity and accuracy the water spectrum in the 12969 - 13172 cm−1 region. While about fifty transitions were previously detected in the region, a total of about 580 water lines are measured by CRDS and rovibrationally assigned, leading to the determination of 103 new levels and correction of 134 levels of H216O. Spectroscopic line lists available in the region (HITRAN, W2020 and theoretical line lists) show some important deviations compared to observations. In particular, line intensities are poorly predicted by available ab initio calculations for transitions involving a highly bending excitation. © 2021 Elsevier Ltd.The support of the CNRS (France) in the frame of International Research Project SAMIA is acknowledged. CRDS measurements and spectrum analysis were performed at IAO-Tomsk and funded by RFBR project 20-32-70054
Highly rough tapered gold and silver tips for polarization- controlled TERS performance
© Published under licence by IOP Publishing Ltd. This paper describes an electrochemical method for producing rough silver and gold taper tips for polarization-controlled TERS performance. This method allows to explore the directional intrinsic properties of the sample due to different dipole moment orientations at the tip apex. We give recommendations for fabricating rough silver and gold tips
DC-pulsed voltage electrochemical method based on duty cycle self-control for producing TERS gold tips
This paper presents a modified dc-pulsed low voltage electrochemical method in which a duty cycle is self tuned while etching. A higher yield of gold tips suitable for performing tip-enhanced Raman scattering (TERS) measurements is demonstrated. The improvement is caused by the self-control of the etching rate along the full surface of the tip. A capability of the gold tips to enhance a Raman signal is exemplified by TERS spectroscopy of single walled carbon nanotubes bundle, sulfur and vanadium oxide. © Published under licence by IOP Publishing Ltd
New transitions and energy levels of water vapor by high sensitivity CRDS near 1.73 and 1.54 µm
This contribution is part of a long term project aiming at improving the water absorption spectroscopy by high sensitivity cavity ring down spectroscopy (CRDS) in the near infrared. Two new sources of CRDS spectra are considered: (i) The room temperature absorption spectrum of water vapor in natural isotopic abundance is recorded near 1.73 µm. A series of recordings was performed from 5693 to 5991 cm−1 with a pressure value of about 6 Torr. The noise equivalent absorption (αmin) of the spectra is better than 10− 10 cm−1. A total of 1453 lines were assigned to 1573 transitions of four water isotopologues (H2 16O, H2 17O, H2 18O and HD16O). Their intensities span more than five orders of magnitude from 3.0 × 10−30 to 4.7 × 10−25 cm/molecule at 296 K. The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Schwenke and Partridge. Two hundred fifty-one lines (assigned to 280 transitions) are observed for the first time and twelve energy levels are newly determined. The comparison of the obtained line parameters with those of the HITRAN database is discussed. Forty-six line positions are observed to significantly differ from their HITRAN values (δν = │νHITRAN – νCRDS│ > 0.02 cm−1). The derived set of energy levels is compared to those recommended by an IUPAC task group. (ii) The room temperature CRDS spectrum of water vapor highly enriched in 17O was recorded near 1.54 µm (6223–6672 cm−1) at a pressure of 12 Torr. Compared to a previous study, the higher pressure of the recordings allowed for extending the observations. Overall, twenty-six new levels were determined for both H2 17O and HD17O. All these observations together with other recent measurements will allow for an extension and an update of our empirical database in the 5693– 8340 cm−1 region. © 2019 Elsevier Lt
Scintillating properties of frozen new liquid scintillators
The light emission from scintillators which are liquid at room temperature was studied in the interval between ~C and ~C, where the phase transition from liquid to solid takes place. The light yield measured at ~C is about twice as much as that observed at ~C. By cooling the scintillator from ~C to ~C and then heating it from ~C to ~C, the light yield varies in steps at well defined temperatures, which are different for the cooling and heating processes. These hysteresis phenomena appear to be related to the solvent rather than to the dopant. The decay time of scintillation light was measured at ~C and ~C. Whilst at room temperature most of the light is emitted with a decay time of 6--8 ns, at ~C a slower component, with a decay time of 25--35 ns, becomes important
Sub-inhibitory Effects of Antimicrobial Peptides
Antimicrobials, and particularly antimicrobial peptides (AMPs), have been thoroughly studied due to their therapeutic potential. The research on their exact mode of action on bacterial cells, especially at under sublethal concentrations, has resulted in a better understanding of the unpredictable nature of bacterial behavior under stress conditions. In this review, we were aiming to gather the wide yet still under-investigated knowledge about various AMPs and their subinhibition effects on cellular and molecular levels. We describe how AMP action is non-linear and unpredictable, also showing that exposure to AMP can lead to antimicrobial resistance via triggering various regulatory systems. Being one of the most known types of antimicrobials, bacteriocins have dual action and can also be utilized by microorganisms as signaling molecules at naturally achievable sub-inhibitory concentrations. The unpredictable nature of AMP action and the pathogenic response triggered by them remains an area of knowledge that requires further investigation
LED-based Fourier transform spectroscopy of H216O in the range 15500-16000 cm-1
The vibrational-rotational absorption spectrum of water vapor within the range 15500–16000 cm−1 is measured and analyzed. The spectrum is recoded with an IFS-125M Fourier transform spectrometer with a resolution of 0.03 cm−1, at pressure of 25 mbar, at a temperature of 24°C, and at an optical path length of 34.8 m. The measurements are performed using a multipass White cell with a base length of 60 cm. A light-emitting diode is used as a radiation source. The signal-to-noise ratio is about 104, which makes it possible to measure the parameters of lines with intensities on the order of 10−27 cm/molecule. The centers, intensities, and half-widths of lines are determined by fitting the Voigt profile parameters to measured data set by the least squares method. A list of more than 430 lines is formed based on the analysis of the spectrum. The obtained results are compared with calculated and experimental data of other authors
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