Precise and ultrafast molecular sieving through graphene oxide membranes

There has been intense interest in filtration and separation properties of graphene-based materials that can have well-defined nanometer pores and exhibit low frictional water flow inside them. Here we investigate molecular permeation through graphene oxide laminates. They are vacuum-tight in the dry state but, if immersed in water, act as molecular sieves blocking all solutes with hydrated radii larger than 4.5A. Smaller ions permeate through the membranes with little impedance, many orders of magnitude faster than the diffusion mechanism can account for. We explain this behavior by a network of nanocapillaries that open up in the hydrated state and accept only species that fit in. The ultrafast separation of small salts is attributed to an 'ion sponge' effect that results in highly concentrated salt solutions inside graphene capillaries

Tracking Rates of Forest Disturbance and Associated Carbon Loss in Areas of Illegal Amber Mining in Ukraine Using Landsat Time Series

Mapping forest disturbance is crucial for many applications related to decision-making for sustainable forest management. This study identified the effect of illegal amber mining on forest change and accumulated carbon stock across a study area of 8125.5 ha in northern Ukraine. Our method relies on the Google Earth Engine (GEE) implementation of the Landsat-based Detection of Trends in Disturbance and Recovery (LandTrendr) temporal segmentation algorithm of Landsat time-series (LTS) to derive yearly maps of forest disturbance and recovery in areas affected by amber extraction operations. We used virtual reality (VR) 360 interactive panoramic images taken from the sites to attribute four levels of forest disturbance associated with the delta normalized burn ratio (dNBR) and then calculated the carbon loss. We revealed that illegal amber extraction in Ukraine has been occurring since the middle of the 1990s, yielding 3260 ha of total disturbed area up to 2019. This study indicated that the area of forest disturbance increased dramatically during 2013–2014, and illegal amber operations persist. As a result, regrowth processes were mapped on only 375 ha of total disturbed area. The results were integrated into the Forest Stewardship Council® (FSC®) quality management system in the region to categorize Forest Management Units (FMUs) conforming to different disturbance rates and taking actions related to their certification status. Moreover, carbon loss evaluation allows the responsible forest management systems to be streamlined and to endorse ecosystem service assessment

An alternative approach to the construction of Schur-Weyl transform

We propose an alternative approach for the construction of the unitary matrix which performs generalized unitary rotations of the system consisting of independent identical subsystems (for example spin system). This matrix, when applied to the system, results in a change of degrees of freedom, uncovering the information hidden in non-local degrees of freedom. This information can be used, inter alia, to study the structure of entangled states, their classification and may be useful for construction of quantum algorithms.Comment: 6 page

Electronic structure, optical and magnetic properties of Co2_{2}FeGe Heusler alloy films

Optical properties of ferromagnetic half-metallic full-Heusler Co$_{2}$FeGe alloy are investigated experimentally and theoretically. Co$_{2}$FeGe thin films were obtained by DC magnetron sputtering and show the saturation magnetization at $T$=10 K of $m\approx$5.6 $\mu_{B}$/f.u., close to the value predicted by the Slater-Pauling rule. First-principles calculations of the electronic structure and the dielectric tensor are performed using the full-potential linearized-augmented-plane-wave method in the generalized gradient (GGA) and GGA+U approximations. The measured interband optical conductivity spectrum for the alloy exhibits a strong absorption band in the 1 - 4 eV energy range with pronounced fine structure, which agrees well with the calculated half-metallic spectrum of the system, suggesting a near perfect spin-polarization in the material.Comment: 6 pages, 9 figure

Nanomechanical electro-optical modulator based on atomic heterostructures

Two-dimensional atomic heterostructures combined with metallic nanostructures allow one to realize strong light–matter interactions. Metallic nanostructures possess plasmonic resonances that can be modulated by graphene gating. In particular, spectrally narrow plasmon resonances potentially allow for very high graphene-enabled modulation depth. However, the modulation depths achieved with this approach have so far been low and the modulation wavelength range limited. Here we demonstrate a device in which a graphene/hexagonal boron nitride heterostructure is suspended over a gold nanostripe array. A gate voltage across these devices alters the location of the two-dimensional crystals, creating strong optical modulation of its reflection spectra at multiple wavelengths: in ultraviolet Fabry–Perot resonances, in visible and near-infrared diffraction-coupled plasmonic resonances and in the mid-infrared range of hexagonal boron nitride's upper Reststrahlen band. Devices can be extremely subwavelength in thickness and exhibit compact and truly broadband modulation of optical signals using heterostructures of two-dimensional materials

ПРОГРАМНИЙ КОМПЛЕКС ДЛЯ ОБРОБКИ СИНХРОННО ЗАРЕЄСТРОВАНИХ БІОСИГНАЛІВ У ПОЛІГРАФАХ

The work described a software package, which provides the compatible statistical processing simultaneously registered in the polygraph biosignals based on a model vector cyclical rhythm associated random processes.В работе описана разработка программного комплекса, который позволяет проводить совместную статистическую обработку синхронно зарегистрированных биосигналов в полиграфах на основе модели вектора циклических ритмично связанных случайных процессов.У роботі описано розробку програмного комплексу, який дає змогу проводити сумісну статистичну обробку синхронно зареєстрованих біосигналів в поліграфах на основі моделі вектора циклічних ритмічно пов'язаних випадкових процесів

Cascaded Optical Field Enhancement in Composite Plasmonic Nanostructures

Copyright © 2010 The American Physical SocietyWe present composite plasmonic nanostructures designed to achieve cascaded enhancement of electromagnetic fields at optical frequencies. Our structures were made with the help of electron-beam lithography and comprise a set of metallic nanodisks placed one above another. The optical properties of reproducible arrays of these structures were studied by using scanning confocal Raman spectroscopy. We show that our composite nanostructures robustly demonstrate dramatic enhancement of the Raman signals when compared to those measured from constituent elements

Pro-russian propaganda recognition and analytics system based on text classification model and statistical data processing methods

In this paper a neural network model for classifying the political polarity of text has been developed, along with a database for training the neural network and an analytics system for pro-Russian propaganda. This allows to classify the political polarity of the message source based on its identifier, as well as to construct and display different networks that represent useful insights about popular Twitter hashtags or Telegram channels that related to Russo Ukrainian War. Also, a user interface has been developed that allows users to interact with the system. Developed system will help people with navigation through the information space and avoidance of pro-Russian propaganda

SETTLEMENTS STATE OF SHELLBACKS SEMIBALANUS BALANOIDES ON INTERTIDAL ZONE OF THE KOLA BAY

This research presents the results of investigation the structure of inter­tidal communities of Semibalanus balanoides of the Kola Bay in the area near the vil­lage Abram-mys and also in Belokamennaya and Pala bays. In the process of research was confirmed the following pattern: abundance of S. balanoides settlement depends on height of the shellbacks house. For all the shellbacks was installed dominant age: 2–3 years. Also were defined abundance and biomass for investigated areas