Abstract The removal of single atomic layers from multi‐layer graphene using a He plasma is reported. By applying sample biases of –60 and +60 V during He plasma exposure, layer removal is found to be due to electrons instead of He ions or neutrals in the plasma. The rate of layer removal depends on exposure time, sample bias, and pre‐annealing treatments. Optical contrast microscopy and atomic force microscopy studies show that the removal of C atoms occurs approximately one layer at a time across the entire multi‐layer sample with no observable production of large pits or reduction in lateral dimensions. Layer removal is proposed to arise from the electron‐stimulated dissociation of C atoms from the basal plane. This process differs from plasma techniques that use reactive species to etch multi‐layer graphene.
The solar cells have been used as most promising device to convert light energy into electrical energy. In this paper authors have attempted to fabricate Photoelectrochemical solar cell with semiconductor electrode using TMDCs. The Photoelectrochemical solar cells are the solar cells which convert the solar energy into electrical energy. The photoelectrochemical cells are clean and inexhaustible sources of energy. The photoelectrochemical solar cells are fabricated using WSe 2 crystal and electrolyte solution of 0.025M I 2 , 0.5M NaI, 0.5M Na 2 SO 4 . Here the WSe 2 crystals were grown by direct vapour transport technique. In our investigations the solar cell parameters like short circuit current (I sc ) and Open circuit voltage (V oc ) were measured and from that Fill factor (F.F.) and photoconversion efficiency (η) are investigated. The results obtained shows that the value of efficiency and fill factor of solar cell varies with the illumination intensities.
The effects of octadecylamine-functionalized reduced graphene oxide (FRGO) on the frictional and wear properties of diglycidylether of bisphenol-A (DGEBA) epoxy are studied using a pin-on-disk tribometer. It was observed that the addition of FRGO significantly improves the tribological, mechanical, and thermal properties of epoxy matrix. Graphene oxide (GO) was functionalized with octadecylamine (ODA), and then reduction of oxygen-containing functional groups was carried out using hydrazine monohydrate. The Raman and x-ray photoelectron spectroscopy studies confirm significant reduction in oxygen-containing functional groups and formation of ODA functionalized reduced GO. The nanocomposites are prepared by adding 0.1, 0.2, 0.5 and 1.0 wt % of FRGO to the epoxy. The addition of FRGO increases by more than an order of magnitude the sliding distance during which the dynamic friction is ≤ 0.1. After this distance, the friction sharply increases to the range of 0.4 - 0.5. We explain the increase in sliding distance during which the friction is low by formation of a transfer film from the nanocomposite to the counterface. The wear rates in the low and high friction regimes are approximately 1.5 x 10-4 mm3/N·m and 5.5 x 10-4 mm3/N·m, respectively. The nanocomposites exhibit a 74 % increase in Young’s modulus with 0.5 wt. % of FRGO, and an increase in glass transition and thermal degradation temperatures.
Abstract: At Present, in Aviation industry there is a strong and rapid growing interest in the development of Urban/Rural Air Mobility (U/RAM) networks, which are aerial transportation systems in, and around major metropolitan areas and rural hilly region where less possibilities of operating big passenger aircraft to cover short distance in challenging geographical location. STOVL capabilities for fixed-wing aircraft is one application of this technology. For rural passenger transport missions in remote area of Nepal, it is risky and difficult during landing in Hilly and Himalayan region due to geographic land structure and slope runway to operate big size passenger or cargo aircraft. Hence, the sole aim of this paper is to present the practical alternative to these problems in the early days of rural air transportation in aviation industries in Nepal. Here, we discuss about the air accidents that occurred in Nepali sky and along with their reason so we decided to try our level best to come up with solution i.e., our proposed design VAAYU YAAN. This paper clarifies the main motive of deploying VAAYU YAAN over conventional aircrafts. It is designed in a such a way that it can solve the problem of fatal accidents in aerial transportation in Hilly and Himalayan region faced as result of topographical difficulties, slope and small runway issues along with air traffic problems and helps in enhancing the public transportation all over the country for regional mobility due to short takeoff and vertical landing capacity. As a result of this feature, due to less risk in mobilization of aerial vehicle in Hilly and Himalayan places, people across the country will be connected and benefited. Keywords: VAAYU YAAN, STOVL, Hilly and Himalayan air mobility, Conceptual Design, Topographical challenges etc.
We report on the fabrication of electrochemical double layer capacitor (EDLC) electrodes with aligned carbon nanotubes (CNTs) grown directly on conductive substrates using an air assisted chemical vapor deposition technique. The fabricated EDLCs showed very small equivalent series resistances (∼few hundreds of mΩ), a direct consequence of integrating CNTs with metal current collectors. The specific capacitance of the CNTs used for EDLC electrodes increased with decreasing CNT lengths and ranged from 10.75 F g−1 to 21.57 F g−1 with maximum energy and power density ranging from 2.3 to 5.4 Wh kg−1 and 19.6 to 35.4 kW kg−1, respectively. These results indicate that the integrated CNT electrodes fabricated using a simple single step process hold significant promise in applications related to electrochemical energy storage.
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