Substrate modification influence on properties of nanocomposite based on TiO2 and gold nanoparticles

In this work, we study photo-induced current transfer through nanocomposite structures consisting of the TiO2 coating activated with plasmonic gold nanoparticles on top of pillar-like structured SiO2. It is shown that the photo-response of the nanocomposite can be adjusted via tuning of the heterostructure topology. Processes at the interface between silicon and noble metal nanoparticle play an important role in charge carrier photo-generation. The high photo-activity in visible part of spectrum has been found in the composite, containing pillar-like silicon dioxide nanostructures [1]. The electron transport via the SiO2 layer from the potential well at the TiO2-SiO2 interface to the n-Si conduction band was explained by electron tunneling mechanism. We present the empirical qualitative model which explains experimental results and helps to separate the contributions of different transport mechanisms

Systematic comparison of ISOLDE-SC yields with calculated in-target production rates

Recently, a series of dedicated inverse-kinematics experiments performed at GSI, Darmstadt, has brought an important progress in our understanding of proton and heavy-ion induced reactions at relativistic energies. The nuclear reaction code ABRABLA that has been developed and benchmarked against the results of these experiments has been used to calculate nuclide production cross sections at different energies and with different targets and beams. These calculations are used to estimate nuclide production rates by protons in thick targets, taking into account the energy loss and the attenuation of the proton beam in the target, as well as the low-energy fission induced by the secondary neutrons. The results are compared to the yields of isotopes of various elements obtained from different targets at CERN-ISOLDE with 600 MeV protons, and the overall extraction efficiencies are deduced. The dependence of these extraction efficiencies on the nuclide half-life is found to follow a simple pattern in many different cases. A simple function is proposed to parameterize this behavior in a way that quantifies the essential properties of the extraction efficiency for the element and the target - ion-source system in question.Comment: 46 pages, 49 figures, background information on http://www-w2k.gsi.de/charms

A blueprint for the synthesis and characterization of thiolated graphene

Graphene derivatization to either engineer its physical and chemical properties or overcome the problem of the facile synthesis of nanographenes is a subject of significant attention in the nanomaterials research community. In this paper, we propose a facile and scalable method for the synthesis of thiolated graphene via a two step liquid phase treatment of graphene oxide GO . Employing the core level methods, the introduction of up to 5.1 at. of thiols is indicated with the simultaneous rise of the C O ratio to 16.8. The crumpling of the graphene layer upon thiolation without its perforation is pointed out by microscopic and Raman studies. The conductance of thiolated graphene is revealed to be driven by the Mott hopping mechanism with the sheet resistance values of 2.15 k amp; 937; sq and dependable on the environment. The preliminary results on the chemiresistive effect of these films upon exposure to ethanol vapors in the mix with dry and humid air are shown. Finally, the work function value and valence band structure of thiolated graphene are analyzed. Taken together, the developed method and findings of the morphology and physics of the thiolated graphene guide the further application of this derivative in energy storage, sensing devices, and smart material

Автоэмиссионные свойства пленок никель - углеродного нанокомпозита

Field-emission properties of Ni-C nanocomposite thin films were experimentally studied. The films were deposited at Si substrates using CVD technique with a metalloorganic precursor and were composed by nm-scale grains of metallic Ni bounded with a carbonic weakly-conducting matrix. In the samples with lower effective thickness, the Ni particles were separated from each other. Such films showed capability of facilitated emission with threshold field values as low as a few V/μm. Thicker coating samples, with metallic particle merged in a conductive layer, required annealing at 470-600 °С in vacuum to produce low-field emission current. The observed emission behavior agrees with the previously proposed model considering low-field emission from nanostructured carbonic materials as a multi-stage process involving generation of hot electrons at interface boundaries.Были исследованы автоэмиссионные свойства тонких пленок никель-углеродного нанокомпозита. Пленки наносились на кремниевые подложки методом химического осаждения с использованием металлорганического прекурсора. Их структура включала в себя наноразмерные зерна металлического никеля, связанные слабопроводящей углеродосодержащей матрицей. В случае покрытий малой эффективной толщины, частицы никеля были отделены друг от друга. Такие пленки демонстрировали способность к низковольтной эмиссии в полях с напряженностью от нескольких В/мкм. В более толстых покрытиях металлические частицы образовывали единый электропроводящий слой. В этом случае для наблюдения низковольтной эмиссии требовался отжиг образцов в вакууме при 470-600 °С. Наблюдавшиеся закономерности эмиссии согласуются с предлагавшейся ранее моделью, которая рассматривает низковольтную эмиссию из наноуглеродных материалов как многостадийный процесс с участием горячих электронов, образующихся на внутренних междоменных границах

Endovascular embolization of pseudotumors in hemophilia patients

The pseudotumors are the serious complication in patients with hemophilia A and B. Surgical excision of hemophilic pseudotumor is frequently accompanied by a massive intraoperative blood loss. The endovascular embolization of the feeding arteries prior to surgery helps to minimize the blood loss and to reduce the size of pseudotumor. We performed endovascular embolization with microcoils in six hemophilia patients with pseudotumors, and describe here three of those cases. © 2018 Izdatel'stvo Meditsina. All rights reserved