203 research outputs found
Induced magnetism of carbon atoms at the graphene/Ni(111) interface
We report an element-specific investigation of electronic and magnetic
properties of the graphene/Ni(111) system. Using magnetic circular dichroism,
the occurrence of an induced magnetic moment of the carbon atoms in the
graphene layer aligned parallel to the Ni 3d magnetization is observed. We
attribute this magnetic moment to the strong hybridization between C and
Ni 3d valence band states. The net magnetic moment of carbon in the graphene
layer is estimated to be in the range of per atom.Comment: 10 pages, 3 figure
Erratum: "Nucleation and growth of nickel nanoclusters on graphene Moiré on Rh(111)" [Appl. Phys. Lett. 96, 093115 (2010)an]
An Artificially Lattice Mismatched Graphene/Metal Interface: Graphene/Ni/Ir(111)
We report the structural and electronic properties of an artificial
graphene/Ni(111) system obtained by the intercalation of a monoatomic layer of
Ni in graphene/Ir(111). Upon intercalation, Ni grows epitaxially on Ir(111),
resulting in a lattice mismatched graphene/Ni system. By performing Scanning
Tunneling Microscopy (STM) measurements and Density Functional Theory (DFT)
calculations, we show that the intercalated Ni layer leads to a pronounced
buckling of the graphene film. At the same time an enhanced interaction is
measured by Angle-Resolved Photo-Emission Spectroscopy (ARPES), showing a clear
transition from a nearly-undisturbed to a strongly-hybridized graphene
-band. A comparison of the intercalation-like graphene system with flat
graphene on bulk Ni(111), and mildly corrugated graphene on Ir(111), allows to
disentangle the two key properties which lead to the observed increased
interaction, namely lattice matching and electronic interaction. Although the
latter determines the strength of the hybridization, we find an important
influence of the local carbon configuration resulting from the lattice
mismatch.Comment: 9 pages, 3 figures, Accepted for publication in Phys. Rev.
Технологические решения для строительства разведочной вертикальной скважины глубиной 3310 метров на нефтяном месторождении (Тюменская область)
Объектом ВКР служит разведочная вертикальная скважина глубиной 3310 метров на нефтяном месторождении. Целью данной работы является – спроектировать технологическое решения для бурения вертикальной разведочной скважины глубиной 3310 метров на нефтяном месторождении Тюменской области. Для достижения поставленной цели были поставлены следующие задачи:
1.Спроектировать конструкцию скважины.
2.Спроектировать процессы углубления скважины.
3.Спроектировать процессы закачивания.The object of the WRC is an exploration vertical well with a depth of 3310 meters in an oil field.
The purpose of this work is to design a technological solution for drilling a vertical exploration well with a depth of 3310 meters at an oil field in the Tyumen region.
To achieve this goal, the following tasks were set:
1. Design the well structure.
2. Design the well deepening processes.
3. Design well completion processes.
4. Consider vibration dampener-calibrator.
5. Design pumping processes
Edge States of Monolayer and Bilayer Graphene Nanoribbons
On the basis of tight-binding lattice model, the edge states of monolayer and
bilayer graphene nanoribbons (GNRs) with different edge terminations are
studied. The effects of edge-hopping modulation, spin-orbital coupling (SOC),
and bias voltage on bilayer GNRs are discussed. We observe the following: (i)
Some new extra edge states can be created by edge-hopping modulation for
monolayer GNRs. (ii) Intralayer Rashba SOC plays a role in depressing the band
energy gap opened by intrinsic SOC for both monolayer and bilayer GNRs.
An almost linear dependent relation, i.e., , is found. (iii)
Although the bias voltage favors a bulk energy gap for bilayer graphene without
intrinsic SOC, it tends to reduce the gap induced by intrinsic SOC. (iv) The
topological phase of the quantum spin Hall effect can be destroyed completely
by interlayer Rashba SOC for bilayer GNRs.Comment: 6 pages, 6 figure
Carbon States in Carbon-Encapsulated Nickel Nanoparticles Studied by Means of X-Ray Absorption, Emission, and Photoelectron Spectroscopies
Electronic structure of nickel nanoparticles encapsulated in carbon was
characterized by photoelectron, X-ray absorption, and X-ray emission
spectroscopies. Experimental spectra are compared with the density of states
calculated in the frame of the density functional theory. The carbon shell of
Ni nanoparticles has been found to be multilayer graphene with significant
(about 6%) amount of Stone--Wales defects. Results of the experiments evidence
protection of the metallic nanoparticles from the environmental degradation by
providing a barrier against oxidation at least for two years. Exposure in air
for 2 years leads to oxidation only of the carbon shell of Ni@C nanoparticles
with coverage of functional groups.Comment: 16 pages, 6 figures, accepted in J. Phys. Chem.
Structurally driven one-dimensional electron confinement in sub-5-nm graphene nanowrinkles
Graphene-based carbon materials such as fullerenes, carbon nanotubes, and graphenes have distinct and unique electronic properties that depend on their dimensionality and geometric structures. Graphene wrinkles with pseudo one-dimensional structures have been observed in a graphene sheet. However, their one-dimensional electronic properties have never been observed because of their large widths. Here we report the unique electronic structure of graphene nanowrinkles in a graphene sheet grown on Ni(111), the width of which was small enough to cause one-dimensional electron confinement. Use of spatially resolved, scanning tunnelling spectroscopy revealed bandgap opening and a one-dimensional van Hove singularity in the graphene nanowrinkles, as well as the chemical potential distribution across the graphene nanowrinkles. This observation allows us to realize a metallic-semiconducting-metallic junction in a single graphene sheet. Our demonstration of one-dimensional electron confinement in graphene provides the novel possibility of controlling its electronic properties not by chemical modification but by 'mechanical structuring'.open
Composite fluoropolymer piezoelectric membranes for reconstructive recovery surgery
In the present study, we performed the results of studies on the formation of composite fluoropolymer piezoelectric membranes based on a copolymer of vinylidene fluoride with tetrafluoroethylene (VDF-TeFE) and polyethylpyrrolidone (PEP) by the electrospinning method. Using scanning electron microscopy, the effect of the PEP content on the structure of the formed membranes was studied. The biocompatibility of the obtained membranes was studied by fluorescence microscopy on a model of human skin fibroblasts. The studied samples with a PEP content of 0, 5, and 15% have good adhesive characteristics, preserve the viability and potential of cells to divide, and therefore are most suitable for further use in regenerative medicine
Проектирование системы электроснабжения производственной базы по обслуживанию нефтяной промышленности
В выпускной работе рассматривается система электроснабжения производственной базы по обслуживанию нефтяной промышленности.
Объектом исследования является прокатно-ремонтный цех производственной базы по обслуживанию нефтяной промышленности.
Цель работы: Разработка системы электроснабжения производственной базы по обслуживанию нефтяной промышленности и развитие способности решать технико-экономические вопросы при проектировании систем электроснабжения.
В процессе исследования проводились расчеты электрических нагрузок прокатно-ремонтного цеха и предприятия в целом, методами коэффициента расчетной активной мощности и коэффициента спроса соответственно. Произведен выбор низковольтного оборудования прокатно-ремонтного цеха и высоковольтного оборудования главной понизительной подстанции.In the graduate qualification work, the system of power supplying production base for servicing the oil industry is considered.
The object of the study is a hire and repair shop of the production base for servicing the oil industry.
Purpose of work: development power supplying system production base for servicing the oil industry and development of the ability to solve technical and economic issues in the design of power supplying systems.
In the process of the study, calculations were made of the electrical loads of the hire and repair shop and the enterprise as a whole, using the methods of the active power factor and the demand factor, respectively. A choice of low-voltage equipment of the hire and repair shop and high-voltage equipment of the main step-down substation were made
Fluctuations, dissipation and the dynamical Casimir effect
Vacuum fluctuations provide a fundamental source of dissipation for systems
coupled to quantum fields by radiation pressure. In the dynamical Casimir
effect, accelerating neutral bodies in free space give rise to the emission of
real photons while experiencing a damping force which plays the role of a
radiation reaction force. Analog models where non-stationary conditions for the
electromagnetic field simulate the presence of moving plates are currently
under experimental investigation. A dissipative force might also appear in the
case of uniform relative motion between two bodies, thus leading to a new kind
of friction mechanism without mechanical contact. In this paper, we review
recent advances on the dynamical Casimir and non-contact friction effects,
highlighting their common physical origin.Comment: 39 pages, 4 figures. Review paper to appear in Lecture Notes in
Physics, Volume on Casimir Physics, edited by Diego Dalvit, Peter Milonni,
David Roberts, and Felipe da Rosa. Minor changes, a reference adde
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