Supercapacitors based on carbon nanomaterials are attracting much attention because of their high capacitance enabled by large specific surface area. The introduction of heteroatoms such as N or O ...enhances the specific capacitance of these materials. However, the mechanisms that lead to the increase in the specific capacitance are not yet well-studied. In this Letter, we demonstrate an effective method for modification of the surface of carbon nanowalls (CNWs) using DC plasma in atmospheres of O2, N2, and their mixture. Processing in the plasma leads to the incorporation of ∼4 atom % nitrogen and ∼10 atom % oxygen atoms. Electrochemical measurements reveal that CNWs functionalized with oxygen groups are characterized by higher capacitance. The specific capacitance for samples with oxygen reaches 8.9 F cm–3 at a scan rate of 20 mV s–1. In contrast, the nitrogen-doped samples demonstrate a specific capacitance of 4.4 F cm–3 at the same scan rate. The mechanism of heteroatom incorporation into the carbon lattice is explained using density functional theory calculations.
Maintenance of non-equilibrium Na
+
and K
+
distribution between cytoplasm and extracellular medium suggests existence of sensors responding with conformational transitions to the changes of these ...monovalent cations’ intracellular concentration. Molecular nature of monovalent cation sensors has been established in Na,K-ATPase, G-protein-coupled receptors, and heat shock proteins structural studies. Recently, it was found that changes in Na
+
and K
+
intracellular concentration are the key factors in the transcription and translation control, respectively. In this review, we summarize results of these studies and discuss physiological and pathophysiological significance of
N
a
i
+
,
K
i
+
-dependent gene expression regulation mechanism.
► Electrodeposition or magnetron sputtering of Cu on carbon nanowalls (Cued/CNW or Cuspr/CNW). ► Galvanic displacement in PtCl42− solution. ► Formation of Pt(Cu)st/CNW catalyst. ► Characterization of ...samples by the complex of methods (SEM, TEM, XPS, voltammetry, polarization curves in CH3OH solutions and so on). ► Discussion of the mechanism of formation and the structure of Pt(Cu)st/CNW.
Microamounts of Cu are applied by the methods of electrodeposition (Cued) and magnetron sputtering (Cuspr) on a new carbon material, carbon nanowalls (CNW). The galvanic displacement (GD) of Cued and Cuspr in a PtCl42− solution (with 0.5M H2SO4 as the supporting electrolyte) produces Pt(Cu)/CNW catalysts. The possibility of using open-circuit potential transients recorded in the course of GD for monitoring the surface layer composition is considered. The stable Pt(Cu)st samples are characterized by several methods (SEM, TEM, XPS, voltammetry, etc.). It is shown that Pt(Cu)st has structure of the core(Pt, Cu)–shell(Pt) type with the average atomic ratio Pt:Cu (%)∼57:43 for Cued and ∼80:20 for Cuspr. The formation of the dense Pt shell is also confirmed by the data on the electrocatalytic activity of synthesized samples in the methanol oxidation reaction. The reasons for deviations in the properties of Pt(Cu)st/CNW samples formed from Cued and Cuspr are discussed. The high specific surfaces of the Pt(Cu)st/CNW catalyst obtained from Cued (>40m2/g Pt) with the simultaneous decrease in the Pt content makes this material promising for using in the platinum-catalyzed processes (particularly, in fuel cells).
The review presents the mechanisms of participation of ions (Na
+
, K
+
, and Ca
2+
) in the processes of synaptic plasticity in the postsynaptic neuron during long-term potentiation and long-term ...depression. It is assumed that the main participants are AMPA and NMDA receptors, voltage-dependent Na
+
, K
+
, Ca
2+
channels, Ca
2+
and Na
+
-activated K
+
channels, ATP-sensitive K
+
channels, and Ca
2+
channels of the endoplasmic reticulum. The review provides their molecular characteristics and discusses their role in long-term potentiation and long-term depression. The significance of changes in the intracellular ratio Na
+
i
/K
+
i
and Ca
2+
-dependent mechanism are considered for the first time from the signal formation to the level of gene expression. We believe that additional research is needed to identify a subset of neuronal genes whose differential expression contributes to synaptic plasticity, which is implemented with the participation of Na
+
i
/K
+
i
-sensitive Ca
2+
-independent “excitation–transcription coupling” mechanism.
Objective
. The aim of the work is to develop a calorimetric stand that allows simulating the operation of an energy-efficient two-evaporator refrigeration unit of a household refrigerator or ...freezer.
Method.
In the course of the work, a calorimetric setup is described that allows conducting experimental studies to determine the cooling capacity and energy efficiency of a modernized refrigeration unit of a household refrigerator.
Result
. Currently, new resource-saving circuit solutions for household refrigeration equipment have been developed. The developed solutions make it possible to increase the efficiency of the refrigeration unit, as well as to reduce its energy consumption. Theoretical calculations confirming these indicators have been carried out. To confirm the calculated values, automated experimental studies are required to determine the parameters of the refrigeration unit. The paper proposes a description of an automated calorimetric stand that allows simulating the operation of an energy-efficient dual-evaporator refrigeration unit of a household refrigerator or freezer.
Conclusion
. The designed calorimetric stand will allow carrying out complex experimental studies to determine the cooling capacity of the modernized refrigeration unit when operating on various refrigerants. The experimental setup also makes it possible to measure the temperature and pressure during the operation of the refrigeration unit, as well as to determine the influence of various factors on its characteristics.
The article presents a hyperspectral reflectance system. The spectral range of the system varies from 480 to 900 nm with a spectral resolution of approximately 5 nm and a spatial resolution of at ...least 0.1 mm. The developed system is able to measure the reflectivity of objects, resulting in a two-dimensional image with full spectral information in each pixel ("hypercube"). The article describes the procedure for image calibration and correction with respect to system artifacts caused by optics and lighting conditions across the entire spectrum. The operation of the hyperspectral imaging system was demonstrated on the samples of the Siberian 12 wheat leaves, healthy and affected by powdery mildew (Blumeria graminis (DC) Speer). The proposed use of the hyperspectral reflectance system is to conduct research in early detection and localization of agricultural plants lesions.
—
An automated interference microscope has been used to determine the rms amplitude of fluctuations of living cells
in vitro
. The geometric thickness of cells has been calculated based on the ...measured optical path differences of light waves and the equivalent elastic constants of these cells have been estimated. The determined rms amplitude of fluctuations of the optical path difference is 0.3–2.7 nm, which corresponds to 4–40 nm rms amplitude of membrane-thickness fluctuations. The amplitudes of fluctuations of spread cells (endothelial cells and macrophages) are smaller relative to unattached cells (
in vitro
red blood cells and lymphocytes). At the same time, the amplitude of fluctuations observed in HeLa tumor cells spread on a substrate exceeds the amplitude of fluctuations of other spread cells (endothelial cells and macrophages). The obtained experimental data are in agreement with the earlier results obtained using other optical methods.
The paper presents a current status of the simulation of the pure CsI crystal calorimeter of the detector of charm-tau factory project in Novosibirsk. The calorimeter employs the scheme with the ...crystals focusing at the beams interaction point to obtain the optimal energy and coordinate resolutions. We present a detailed description of the calorimeter design, optimized using the specially developed parametrized crystal geometry generator. The report also presents the results for the coordinate and energy correction functions calculation. After application of these corrections the estimation of the photon energy and coordinate resolutions for the ideal conditions of negligibly small stochastic, electronic and pileup noises was performed. The π0 reconstruction efficiency and mass resolution depending on it's momentum were also determined.
Highly transparent YAG:Ce ceramics (transmission of 72–82% for 2-mm-thick samples in 550–900 nm wavelength range) were fabricated by solid-state reactive sintering using a mixture of Ce2xY2-2xO3 ...(x = 0.001, 0.01, 0.03, and 0.05) and Al2O3 nanopowders synthesized by laser ablation with an additional round of pre-calcining before compaction. The synthesized YAG:Ce ceramic materials showed intense luminescence with a maximum at 525–545 nm. The measured absolute light yields of the synthesized YAG:Ce ceramics were 18–21 photon/MeV for 1–5 at.% Ce and 5 photon/MeV for 0.1 at.% Ce. The energy resolutions of the fabricated thin ceramic samples (2 mm) under 662 keV gamma ray were measured to be 10–15%. The decay curves of scintillations consisted of two components with the decay times depending on the Ce3+ concentration. The sample doped with 5 at.% of Ce exhibited the main fast component with 26 ns decay time. The measured data was compared to that of YAG:Ce and well-known CsI:Tl single crystal scintillators. The influence of dopant concentration on the optical, luminescence and scintillation properties was discussed.
•Highly transparent YAG-Ce ceramics were synthesized.•The decay constant of 5%Ce-YAG ceramic is 26 ns.•The absolute light yield of 1%Ce-YAG ceramic is 20 ph/MeV.
The thermal decomposition of the energetic component and chemical reactions occurring at elevated temperatures in a flameless combustion wave of systems based on hexogen (filled with iron(II) formate ...and polyisocyanurate binding agent) afford a mixture of iron oxides and iron nitride as nanosized particles. The purposeful change in the ratio of the indicated basis components can provide individual Fe
2
O
3
, Fe
3
O
4
, or FeO in the conversion products. Additives of anthracene and hydroquinone to the initial composition can result in the formation of predominantly iron carbide in the products, whereas mainly iron nitrides are formed upon the addition of guanidine nitrate or 5-aminotetrazole. The addition of aluminum hydride components to the initial mixture results in the reduction of iron to the zero-valence state in the form of iron—aluminum intermetallic compounds.
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