scholarly journals New 2D graphene hybrid composites as an effective base element of optical nanodevices

2018 ◽  
Vol 9 ◽  
pp. 1321-1327 ◽  
Author(s):  
Olga E Glukhova ◽  
Igor S Nefedov ◽  
Alexander S Shalin ◽  
Мichael М Slepchenkov
Keyword(s):  
Absorption Coefficient ◽  
Hybrid Composites ◽  
Angle Of Incidence ◽  
Hybrid Nanocomposite ◽  
Base Element ◽  
Different Diameters ◽  
New Generation ◽  
Semiconductor Nanotubes ◽  
First Time ◽  
Topological Models

For the first time, we estimated perspectives for using a new 2D carbon nanotube (CNT)–graphene hybrid nanocomposite as a base element of a new generation o optical nanodevices. The 2D CNT–graphene hybrid nanocomposite was modelled by two graphene monolayers between which single-walled CNTs with different diameters were regularly arranged at different distances from each other. Spectra of the real and imaginary parts of the diagonal elements of the surface conductivity tensor for four topological models of the hybrid nanocomposite have been obtained. The absorption coefficient for p-polarized and s-polarized radiation was calculated for different topological models of the hybrid nanocomposite. It was found that the characteristic peaks with high intensity appear in the UV region at wavelengths from 150 to 350 nm (related to graphene) and in the optical range from 380 to 740 nm irrespective of the diameter of the tubes and the distance between them. For waves corresponding to the most intense peaks, the absorption coefficient as a function of the angle of incidence was calculated. It was shown that the optical properties of the hybrid nanocomposite were approximately equal for both metallic and semiconductor nanotubes.

Recent developments in low-voltage SEM of polymers

1993 ◽  
Vol 51 ◽  
pp. 866-867
Author(s):  
S.J. Krause ◽  
W.W. Adams
Keyword(s):  
Low Voltage ◽  
Chromatic Aberration ◽  
Thermal Electron ◽  
Analytical Technique ◽  
Recent Developments ◽  
Beam Currents ◽  
New Generation ◽  
First Time ◽  
Voltage Scanning ◽  
Beam Damage

Over the past decade low voltage scanning electron microscopy (LVSEM) of polymers has evolved from an interesting curiosity to a powerful analytical technique. This development has been driven by improved instrumentation and in particular, reliable field emission gun (FEG) SEMs. The usefulness of LVSEM has also grown because of an improved theoretical and experimental understanding of sample-beam interactions and by advances in sample preparation and operating techniques. This paper will review progress in polymer LVSEM and present recent results and developments in the field.In the early 1980s a new generation of SEMs produced beam currents that were sufficient to allow imaging at low voltages from 5keV to 0.5 keV. Thus, for the first time, it became possible to routinely image uncoated polymers at voltages below their negative charging threshold, the "second crossover", E2 (Fig. 1). LVSEM also improved contrast and reduced beam damage in sputter metal coated polymers. Unfortunately, resolution was limited to a few tenths of a micron due to the low brightness and chromatic aberration of thermal electron emission sources.

scholarly journals Electrodeposition of Copper and Brass Coatings with Olive-Like Structure

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1762
Author(s):  
Artur Maciej ◽  
Natalia Łatanik ◽  
Maciej Sowa ◽  
Izabela Matuła ◽  
Wojciech Simka
Keyword(s):  
Corrosion Resistance ◽  
Cathodic Current Density ◽  
Bath Composition ◽  
Cathodic Current ◽  
Corrosion Properties ◽  
Fine Grained ◽  
Electrodeposited Coating ◽  
Copper Zinc ◽  
New Generation ◽  
First Time

One method of creating a brass coating is through electrodeposition, which is most often completed in cyanide galvanic baths. Due to their toxicity, many investigations focused on the development of more environmentally friendly alternatives. The purpose of the study was to explore a new generation of non-aqueous cyanide-free baths based on 1-ethyl-3-methylimidazolium acetate ionic liquids. The study involved the formation of copper, zinc, and brass coatings. The influence of the bath composition, cathodic current density, and temperature was determined. The obtained coatings were characterized in terms of their morphology, chemical composition, phase composition, roughness, and corrosion resistance. It was found that the structure of the obtained coatings is strongly dependent on the process parameters. The three main structure types observed were as follows: fine-grained, porous, and olive-like. To the best knowledge of the authors, it is the first time the olive-like structure was observed in the case of an electrodeposited coating. The Cu-Zn coatings consisted of 19–96 at. % copper and exhibited relatively good corrosion resistance. A significant improvement of corrosion properties was found in the case of copper and brass coatings with the olive-like structure.

El español de la isla de La Graciosa desde una perspectiva prosódica

2021 ◽  
Vol 137 (2) ◽  
pp. 451-476
Author(s):  
Imelda Chaxiraxi Díaz Cabrera ◽  
Carolina Jorge Trujillo
Keyword(s):  
Canary Islands ◽  
Grammatical Morphology ◽  
Paper Format ◽  
New Generation ◽  
First Time ◽  
The Town

Abstract Manuel Alvar published the only linguistic work known on Spanish from the island of La Graciosa (Canary Islands) in 1965, focused on the town of Caleta del Sebo, to document, in the field of Linguistic geography, the ALEICan (Linguistic and ethnographic atlas of the Canary Islands [1975–1978]). Alvar’s studies used to cover the lexical, grammatical (morphology and syntax) and phonetic levels of the segmental type, but he did not consider prosodic aspects of speech which would later be incorporated into a new generation of atlases, which would go from paper format to multimedia. As the main exponent, the AMPER project (Atlas Multimédia Prosodique de l’Espace Roman) was created in 2001 and, within its framework, we intend to describe the melodic characteristics of a group of sentences emitted by a man and a woman from Caleta del Sebo, completing thus the study started by Alvar fifty-five years ago. In this way, the results will show for the first time if there is a prosodic proximity between the eighth island and the seven main islands, which have been widely described in previous works both in formal and in informal speech.

Graphene/chitosan/Ag+- doped hydroxyapatite triple composite fiber coatings on new generation hybrid titanium composite by electrospinning

2021 ◽  
pp. 002199832110075
Author(s):  
Tuğba Mutuk ◽  
Mevlüt Gürbüz
Keyword(s):  
Hybrid Composites ◽  
Graphene Nanosheets ◽  
Pure Titanium ◽  
Composite Fiber ◽  
Mass Change ◽  
Coated Materials ◽  
Nano Fiber ◽  
Hybrid Nanofiber ◽  
New Generation ◽  
Fiber Coatings

In this work, The hybrid hydroxyapatite (HaP), chitosan (CH) and graphene nanosheets (GNS) mixtures were applied by electrospinning on the surface of GNS and Si3N4 (SN) binary powder reinforced hybrid titanium (Ti) metal composites surface to improve composite biosurface functionallity. The surfaces of coated materials were characterized and antibacterial tests were carried on for their suitability in the industry by performing artificial body fluid tests. The hybrid nano fiber coatings formed a homogeneous structure on the composite. According to bioactivity tests and microstructure analysis, it was seen that HaP, which has the best results in the change of pH (pH= 11.80) values. The lowest mass change (0.0005 g) was observed on the 10th day of pure titanium. The highest mass change (0.0210 g) was obtained as on the HaP coated hybrid titanium composite. According to the antibacterial test result the hybrid nanofiber containing silver (Ag+) doped HaP on Ti composites showed the best antibacterial property aganist the E.coli. The fabricated electrospin coated hybrid composites can be a potantial candidate for dental, orthopedic implant applications and tissue engineering.

scholarly journals Revealing noncollinear magnetic ordering at the atomic scale via XMCD

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fridtjof Kielgast ◽  
Ivan Baev ◽  
Torben Beeck ◽  
Federico Pressacco ◽  
Michael Martins
Keyword(s):  
Ground State ◽  
Magnetic Circular Dichroism ◽  
Magnetic Moments ◽  
Magnetic Ordering ◽  
Atomic Scale ◽  
Angle Of Incidence ◽  
X Ray ◽  
First Time ◽  
X Ray Absorption ◽  
Magnetic Sublattices

AbstractMass-selected V and Fe monomers, as well as the heterodimer $${\text{Fe}}_1{\text{V}}_1$$ Fe 1 V 1 , were deposited on a Cu(001) surface. Their electronic and magnetic properties were investigated via X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy. Anisotropies in the magnetic moments of the deposited species could be examined by means of angle resolving XMCD, i.e. changing the X-ray angle of incidence. A weak adatom-substrate-coupling was found for both elements and, using group theoretical arguments, the ground state symmetries of the adatoms were determined. For the dimer, a switching from antiparallel to parallel orientation of the respective magnetic moments was observed. We show that this is due to the existence of a noncollinear spin-flop phase in the deposited dimers, which could be observed for the first time in such a small system. Making use of the two magnetic sublattices model, we were able to find the relative orientations for the dimer magnetic moments for different incidence angles.

scholarly journals Meteor head echo polarization at 930 MHz studied with the EISCAT UHF HPLA radar

2011 ◽  
Vol 29 (6) ◽  
pp. 1197-1208 ◽  
Author(s):  
G. Wannberg ◽  
A. Westman ◽  
A. Pellinen-Wannberg
Keyword(s):  
Angle Of Incidence ◽  
Resonance Effects ◽  
Observation Volume ◽  
Polarization Characteristics ◽  
Radar Measurements ◽  
Head Echo ◽  
Using Data ◽  
Static Head ◽  
First Time ◽  
Underdense Plasma

Abstract. The polarization characteristics of 930-MHz meteor head echoes have been studied for the first time, using data obtained in a series of radar measurements carried out with the tristatic EISCAT UHF high power, large aperture (HPLA) radar system in October 2009. An analysis of 44 tri-static head echo events shows that the polarization of the echo signal recorded by the Kiruna receiver often fluctuates strongly on time scales of tens of microseconds, illustrating that the scattering process is essentially stochastic. On longer timescales (> milliseconds), more than 90 % of the recorded events show an average polarization signature that is independent of meteor direction of arrival and echo strength and equal to that of an incoherent-scatter return from underdense plasma filling the tristatic observation volume. This shows that the head echo plasma targets scatter isotropically, which in turn implies that they are much smaller than the 33-cm wavelength and close to spherically symmetric, in very good agreement with results from a previous EISCAT UHF study of the head echo RCS/meteor angle-of-incidence relationship. Significant polarization is present in only three events with unique target trajectories. These all show a larger effective target cross section transverse to the trajectory than parallel to it. We propose that the observed polarization may be a signature of a transverse charge separation plasma resonance in the region immediately behind the meteor head, similar to the resonance effects previously discussed in connection with meteor trail echoes by Herlofson, Billam and Browne, Jones and Jones and others.

45° REFLECTOMETRY OF SEMICONDUCTOR QUANTUM WELLS

2001 ◽  
Vol 15 (17n19) ◽  
pp. 683-687
Author(s):  
A. SILVA-CASTILLO ◽  
F. PEREZ-RODRIGUEZ
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Growth Direction ◽  
Angle Of Incidence ◽  
Near Surface ◽  
New Information ◽  
Difference Formula ◽  
Exciton Polaritons ◽  
The Difference ◽  
First Time

We have applied the 45° reflectometry for the first time to study exciton-polaritons in quantum wells. The 45° reflectometry is a new polarization-modulation technique, which is based on the measurement of the difference [Formula: see text] between the p-polarization reflectivity (Rp) and the squared s-polarization reflectivity [Formula: see text] at an angle of incidence of 45°. We show that [Formula: see text] spectra may provide qualitatively new information on the exciton-polariton modes in a quantum well. These optical spectra turn out to be very sensitive to the zeros of the dielectric function along the quantum-well growth direction and, therefore, allow to identify the resonances associated with the Z exciton-polariton mode. We demonstrate that 45° reflectometry could be a powerful tool for studying Z exciton-polariton modes in near-surface quantum wells, which are difficult to observe in simple spectra of reflectivity Rp

Swift catalytic reduction of hazardous pollutants by new generation microgels

Soft Matter ◽  
2021 ◽  
Author(s):  
Vinai Kumar Singh ◽  
Krishna Kumar ◽  
Nishant Singh ◽  
Rudramani Tiwari ◽  
S. Krishnamoorthi
Keyword(s):  
Catalytic Reduction ◽  
Cross Linker ◽  
Hazardous Pollutants ◽  
New Generation ◽  
First Time

In this manuscript, we first time report the new generation microgel synthesis without using any divinyl functionalized cross-linker. New generation less crosslinked microgel structure has been achieved by optimizing the...

Microstrip Gas Counters

2014 ◽  
pp. 31-51
Keyword(s):  
Glass Surface ◽  
Two Dimensional ◽  
Large Area ◽  
Proportional Chamber ◽  
Microelectronic Technology ◽  
Multiwire Proportional Chamber ◽  
Dimensional Version ◽  
A Chain ◽  
New Generation ◽  
First Time

In this chapter, the first micropattern gaseous detector, the microstrip gas counter, invented in 1988 by A. Oed, is presented. It consists of alternating anode and cathode strips with a pitch of less than 1 mm created on a glass surface. It can be considered a two-dimensional version of a multiwire proportional chamber. This was the first time microelectronic technology was applied to manufacturing of gaseous detectors. This pioneering work offers new possibilities for large area planar detectors with small gaps between the anode and the cathode electrodes (less than 0.1 mm). Initially, this detector suffered from several serious problems, such as charging up of the substrate, discharges which destroyed the thin anode strips, etc. However, by efforts of the international RD28 collaboration hosted by CERN, most of them were solved. Although nowadays this detector has very limited applications, its importance was that it triggered a chain of similar developments made by various groups, and these collective efforts finally led to the creation of a new generation of gaseous detectors-micropattern detectors.

Biomimetic nanofiber by electrospinning of snail mucus

2020 ◽  
Vol 12 ◽  
Author(s):  
Congcong Zhu ◽  
Tianyi Zhong ◽  
Baoqi Zuo
Keyword(s):  
Crucial Role ◽  
Natural Fiber ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Fibrous Structure ◽  
Dissolution Time ◽  
Active Compounds ◽  
Different Diameters ◽  
First Time ◽  
Biomimetic Nanofibers

Background: Snail mucus (SM) is secreted by the pedal gland of snails, and has a fibrous structure when it crawls upside down on the plane. It contains biologically active compounds that have medical functions, such as glycol acid, natural antibiotics, and glycoprotein. Methods: For this paper, we prepared fibers using electrospinning to simulate this natural fiber for the first time, and we can produce the nanofiber with mucus from a snail. The effects of dissolution time and the spun solution were also investigated. Result: The results show that biomimetic nanofibers with different diameters can be obtained using electrospinning. When the concentration of the spun liquid was increased from 6wt% to 8wt%, a fiber with about a 200 nm diameter can be obtained. Adjusting the concentration plays a crucial role in electrospinning.

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