It is commonly believed that thermal energy remaining in a target is negligible following femtosecond laser ablation. In contrast to this belief, however, we observe a significant enhancement in ...thermal energy retained in a target following single-pulse ablation. Ambient gas plasmas produced near the sample surface are shown to play a key role in the enhanced residual energy coupling. Our study reveals, for the first time, an enhanced energy coupling in single-shot high-intensity femtosecond laser-metal interactions and provides new guidelines for a broad range of technological applications.
A new method for extractive-catalytic fractionation of aspen wood to produce microcrystalline (MCC), microfibrillated (MFC), nanofibrilllated (NFC) celluloses, xylan, and ethanollignin is suggested ...in order to utilize all of the main components of wood biomass. Xylan is obtained with a yield of 10.2 wt.% via aqueous alkali extraction at room temperature. Ethanollignin was obtained with a yield of 11.2 wt.% via extraction with 60% ethanol from the xylan-free wood at 190 °C. The lignocellulose residue formed after the extraction of xylan and ethanollignin was subjected to catalytic peroxide delignification in the acetic acid-water medium at 100 °C in order to obtain microcrystalline cellulose. MCC is hydrolyzed with 56% sulfuric acid and treated with ultrasound to produce microfibrillated cellulose and nanofibrillated cellulose. The yields of MFC and NFC were 14.4 and 19.0 wt.%, respectively. The average hydrodynamic diameter of NFC particles was 36.6 nm, the crystallinity index was 0.86, and the average zeta-potential was 41.5 mV. The composition and structure of xylan, ethanollignin, cellulose product, MCC, MFC, and NFC obtained from aspen wood were characterized using elemental and chemical analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, Gas chromatography (GC), Gel permeation-chromatography (GPC), Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Dynamic light scattering (DLS), Thermal gravimetric analysis (TGA).
The anodes based on the nickel oxide and yttria-stabilized zirconia are developed by the method of hybrid inkjet 3D-printing with laser treatment. The granulometric composition of the NiO/Zr
0.9
Y
...0.1
O
2
-composite and the rheological characteristics of its based printing pastes are determined. The printing of three-dimensional test objects using the developed ceramic paste is studied experimentally. The influence of the pore formers—graphite and potato starch—added to the paste composition on the rheological characteristics of the paste is studied. The obtained samples of supporting anodes were studied by a complex of physicochemical methods to determine their morphological and structural characteristics.
We calculated the electron susceptibility of rare-earth tritelluride compounds RTe
as a function of temperature, wave vector, and electron-dispersion parameters. Comparison of the results obtained ...with the available experimental data on the transition temperature and on the wave vector of a charge-density wave in these compounds allowed us to predict the values and evolution of electron-dispersion parameters with the variation of the atomic number of rare-earth elements (R).
Abstract
In this paper, the theoretical study of LED based on GaN NWs with carbon nanotubes (CNT) top contact has been presented. The main electrical and optical characteristics of LED have been ...numerically calculated. In a 0.5 x 0.5 mm NWs array, the Ohmic losses in CNTs were 2.7% with an operating current density of 50 A/cm
2
. It proves the possibility of using CNTs as transparent contact.
Using the Geant4 software package, a numerical simulation of a neutron source of the time-offlight spectrometer GNEIS created on the basis of the SC-1000 synchrocyclotron with 1 GeV proton energy at ...the NRC Kurchatov Institute—PNPI (Gatchina) has been carried out. The influence of the structural features of the neutron source of the spectrometer on the spatial and energy distributions of neutrons has been studied. The intensity and spectral characteristics of the neutron flux in the range of 1–1000 MeV have been determined on the basis of the obtained information and detailed allowance for all elements of the neutron beam guide system. It is found that the best agreement between the experiment and calculation performed by means of Geant4 is observed when using the QGSP_INCLXX_HP model. In the neutron energy range of 1–200 MeV, the difference between the experimental and calculated shapes of the spectra is less than 25%.
Tailorable synthesis of axially heterostructured epitaxial nanowires (NWs) with a proper choice of materials allows for the fabrication of novel photonic devices, such as a nanoemitter in the ...resonant cavity. An example of the structure is a GaP nanowire with ternary GaPAs insertions in the form of nano-sized discs studied in this work. With the use of the micro-photoluminescence technique and numerical calculations, we experimentally and theoretically study photoluminescence emission in individual heterostructured NWs. Due to the high refractive index and near-zero absorption through the emission band, the photoluminescence signal tends to couple into the nanowire cavity acting as a Fabry-Perot resonator, while weak radiation propagating perpendicular to the nanowire axis is registered in the vicinity of each nano-sized disc. Thus, within the heterostructured nanowire, both amplitude and spectrally anisotropic photoluminescent signals can be achieved. Numerical modeling of the nanowire with insertions emitting in infrared demonstrates a decay in the emission directivity and simultaneous rise of the emitters coupling with an increase in the wavelength. The emergence of modulated and non-modulated radiation is discussed, and possible nanophotonic applications are considered.
This work is aimed at finding and developing new ways to improve and optimize the characteristics of transparent conductive electrodes based on SWCNT by forming a texture in a continuous layer by ...combination of lithography and oxygen plasma treatment. A theoretical and an experimental justification for choosing thickness of a textured pattern, together with the experimental results of optical and electrophysical measurements were presented. The resistance of the textured electrode was 187.5 Ohm/sq, which is 17.5% lower than resistance of the electrode made from a continuous SWCNT layer with a same transparency of 95%. An analytical calculation showed that the use of extremely absorbing SWCNT films for texturing allows to obtain ∼ 54% gain in the resistance of a textured electrode compared to a continuous SWCNT's layer.
Spontaneously formed temperature-frequency zone of negative dielectric permittivity ε′<0 was found in polymer-water system “poly(acylic acid)+3wt% of moisture”. Nucleation and evolution of the zone ...is demonstrated on ε′(f,T), ε″(f,T) and tgδ(f,T) 3D plots. Bound water release at T>65°C is thought to be the reason of this phenomenon. The frequency width of the zone steadily increases with temperature up to T=83°C, and then sharply increases at low-frequency side. This effect might be related to the anomalies in temperature dependencies of thermodepolarization currents in water at 83°C. Spontaneous manifestation of ε′<0 phenomenon indicates that one can expect it in natural materials, including biopolymers, i.e. in living organisms.
•Dielectric properties of poly(acrylic acid) pressed pellets with different wt% of moisture were studied.•Temperature-frequency zones of negative dielectric permittivity were detected.•Bound water release at T>65°C is responsible for the phenomenon.
The urgency of the problem being investigated is due to the constant presence of traffic jams on the major cities streets caused by various traffic incidents, which dramatically reduce the traffic ...capacity of the roadway and impede an unhindered passage for road users. One of the ways to solve this problem is the institute of emergency commissioners, which currently does not fully perform the functions imposed on it. In particular, the late arrival at the crash site contributes to the appearance of traffic jam. The paper proposes a scientifically based approach to solving the problem of rational crew's deployment of emergency commissioners in the urban area. The article materials may be useful for regulation of the services of emergency commissioners, the State Traffic Safety Inspectorate, and for coordinating their cooperation with insurance companies.
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