Littoral phytocenoses of marshes located in different tidal conditions of the White Sea

This paper describes the distribution of plant communities from various associations, identified from the standpoint of the ecological-phytocenotic approach, occupying the tidal flat of low and medium marshes, which are under the influence of tide range, different values of pH and water salinity. According to the degree of pH influence, we identified acidotrophic, alkalotrophic, and indifferent phytocenoses, combined into different associations. Most associations of the estuaries with different tide range are alkalotrophic, there are noticeably fewer acidotrophic ones; a few eurytopic communities from the Phragmitetum australis, Bolboschoenetum maritimae, and Caricetum aquatilis associations are classified as indifferent. The study shows that the coastal vegetation of the marshes of the mesotidal estuaries of the White Sea develops in stable pH conditions in the range from 7.2 to 7.6. The formation of coastal vegetation is less stable in the macrotidal estuaries of the Mezen Bay, most of them form at pH = 7.0-8.3. Halophyte vegetation forms in the widest range of pH (6.2-8.3) in the marshes of microtidal estuaries in the Dvina Bay of the White Sea, which are more affected by floods than other estuaries. The halophytic vegetation of the White Sea develops in a wide range of salinity fluctuations from brackish to marine waters. However, the majority of plant associations in the rivers estuaries occupy the habitats of weakly saline waters with 10 to 25% salinity

Controlling Boron Diffusion during Rapid Thermal Annealing with CoImplantation by Amphoteric Impurity Atoms

A model for simulating the rapid thermal annealing of silicon structures implanted with boron and carbon is developed. The model provides a fair approximation of the process of boron diffusion in silicon, allowing for such effects as the electric field, the impact of the implanted carbon, and the clustering of boron. The migration process of interstitials is described according to their drift in the field of internal elastic stress

Artificial multiferroic structures using soft magnetostrictive bilayers on Pb(Mg1/3Nb2/3)-PbTiO3

Artificial multiferroic structures are of great interest as they combine two or more functionalities together. One example of these structures are magnetostrictive films grown on top of piezoelectric substrates; allowing the magnetisation hysteresis loop of the magnetostrictive film to be manipulated using an electric field across the structure rather than a magnetic field. In this paper, we have studied the multiferroic structure NiFe/FeCo/Ti/Pb(Mg1/3Nb2/3)-PbTiO3 (PMN-PT) as a function of the electric and magnetic field. Soft magnetostrictive bilayer films (NiFe/FeCo) are studied, as often applications require soft magnetic properties (small coercive and anisotropy fields) combined with larger magnetostrictive constants. Unfortunately, FeCo films can have coercive fields that are too large, while NiFe films’ magnetostriction constants are almost zero; thus, combining the two together should produce the “ideal” soft magnetostrictive film. It was found that the addition of a thin NiFe film onto the FeCo film reduced the coercive field and remnant magnetisation on the application of an applied voltage in comparison to just the FeCo film. It was also determined that for the NiFe/FeCo bilayer the magnetisation switchability was ~100% on the application of 8kV/cm, which was higher than the monolayer FeCo films at the same applied field, demonstrating improvement of the multiferroic behaviour by the soft magnetic/magnetostrictive bilayer

Electro-optical response of PDLC films with conical boundary conditions

Polymer dispersed liquid crystals (PDLC) are the liquid crystal (LC) droplets dispersed in polymer matrix. Optical properties of such composite materials depend on the orientational structure inside droplets which, in turn, depends on the boundary conditions at LC-polymer interface. For instance, the bipolar director configuration with two point defects at the opposite droplet's poles is formed within droplets at tangential surface anchoring. An electric field applied to this PDLC film causes the transformation of orientational structure and reorientation of bipolar droplet axis along the field. In the result, PDLC film can be switched from a ight-scattering state to transparent one

МОДЕЛИРОВАНИЕ ПРОЦЕССОВ ИОННОЙ ИМПЛАНТАЦИИ И БЫСТРЫХ ТЕРМООБРАБОТОК ПРИ ФОРМИРОВАНИИ АКТИВНЫХ ОБЛАСТЕЙ СУБМИКРОННЫХ И НАНОМЕТРОВЫХ ИНТЕГРАЛЬНЫХ СХЕМ НА КРЕМНИИ

The physical models and numerical algorithms allowing one to accurately simulate advanced technological processes, such as low−energy ion implantation and rapid thermal processing (RTA) are presented. A software system on the basis of these models has been designed and integrated into the microelectronics device and process modeling system Silvaco ATHENA. It enables the use of models and calculationmethods alternative to those implemented in the well−known software products, mainly for solving the problems with shallow depths of doped regionsРассмотрены физико−математические модели и численные алгоритмы, позволяющие достаточно точно моделировать современные технологические процессы, такие как низкоэнергетическая ионная имплантация и быстрая термообработка. Разработанный на основе этих моделей программный комплекс, интегрированный в систему сквозного моделирования процессов и приборов интегральной электроники Silvaco ATHENA, дает возможность использовать модели и методы расчета, альтернативные реализованным в известных программных продуктах, главным образом в решении задач с малой глубиной формируемых легированных областей

Conserved Expression of the Glutamate NMDA Receptor 1 Subunit Splice Variants during the Development of the Siberian Hamster Suprachiasmatic Nucleus

Glutamate neurotransmission and the N-methyl-D-aspartate receptor (NMDAR) are central to photic signaling to the master circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). NMDARs also play important roles in brain development including visual input circuits. The functional NMDAR is comprised of multiple subunits, but each requiring the NR1 subunit for normal activity. The NR1 can be alternatively spliced to produce isoforms that confer different functional properties on the NMDAR. The SCN undergoes extensive developmental changes during postnatal life, including synaptogenesis and acquisition of photic signaling. These changes are especially important in the highly photoperiodic Siberian hamster, in which development of sensitivity to photic cues within the SCN could impact early physiological programming. In this study we examined the expression of NR1 isoforms in the hamster at different developmental ages. Gene expression in the forebrain was quantified by in situ hybridization using oligonucleotide probes specific to alternatively spliced regions of the NR1 heteronuclear mRNA, including examination of anterior hypothalamus, piriform cortex, caudate-putamen, thalamus and hippocampus. Gene expression analysis within the SCN revealed the absence of the N1 cassette, the presence of the C2 cassette alone and the combined absence of C1 and C2 cassettes, indicating that the dominant splice variants are NR1-2a and NR1-4a. Whilst we observe changes at different developmental ages in levels of NR1 isoform probe hybridization in various forebrain structures, we find no significant changes within the SCN. This suggests that a switch in NR1 isoform does not underlie or is not produced by developmental changes within the hamster SCN. Consistency of the NR1 isoforms would ensure that the response of the SCN cells to photic signals remains stable throughout life, an important aspect of the function of the SCN as a responder to environmental changes in quality/quantity of light over the circadian day and annual cycle

Controlling Boron Diffusion during Rapid Thermal Annealing with CoImplantation by Amphoteric Impurity Atoms

A model for simulating the rapid thermal annealing of silicon structures implanted with boron and carbon is developed. The model provides a fair approximation of the process of boron diffusion in silicon, allowing for such effects as the electric field, the impact of the implanted carbon, and the clustering of boron. The migration process of interstitials is described according to their drift in the field of internal elastic stress

Formation of InAs Nanoclusters in Silicon by High-Dose Ion Implantation: Experimental Data and Simulation Results

A physicomathematical model and dedicated software are developed for simulating high-dose implantation of two types of atoms to form InAs nanoclusters in a silicon matrix. The model is based on solving a set of convection–diffusion–reaction equations. The synthesis of InAs nanoclusters produced by high-dose implantation of As+ and In+ ions into crystalline silicon is numerically simulated. Using the methods of transmission electron microscopy and Raman scattering, it is found that InAs nanoclusters are crystalline and have a mean diameter of 7 nm. After As implantation (170 keV, 3.2 × 1016 cm–2) and In implantation (250keV, 2.8 × 1016 cm–2) into silicon at 500°C, the nanoclusters are distributed with a density of 2.8 × 1016 cm–2. From experimental data and theoretical results, the coefficients of radiation-stimulated diffusion of In and As in silicon, as well as the fraction of the implant in the bound state (i.e., entering into InAs nanoclusters), are determined. Experimental data are compared with simulation result