Influence of growth parameters on the dopant configuration of nitrogen-doped graphene synthesized from phthalocyanine molecules

Synthesis of nitrogen-doped graphene (NDG) via chemical vapor deposition (CVD) using phthalocyanine, a solid precursor containing carbon and nitrogen, is reported. The effect of the growth parameters (temperature, time, and carrier gas) on the surface morphology, dopant configuration, and conductivity of the films was studied. The NDG films were synthesized at different substrate temperatures of 1050 °C, 950 °C, and 850 °C for different growth times of 5–15 min in the presence of an Ar?+?H₂ gas mixture. Significantly, pyrrolic-N type defects are observed predominantly after 5 min of growth time. At 1050 °C, pyrrolic N content is around 45.4% after 5 min of growth which decreased to 24.1% after 15 min of growth, while the graphitic-N content increased from 41.2 to 76% at the same time. It is demonstrated that the conversion of pyrrolic type of nitrogen to graphitic nitrogen defects can be arrested by changing the carrier gas from Ar?+?H₂ to Ar. The pyrrolic-N content increased to 64% by changing the gas from Ar?+?H₂ to Ar at 15 min. The electrolyte gated field-effect transistors were fabricated using the obtained films, and dopant-dependent mobility was observed. The mobility for pyrrolic-N-dominated film is 13.6 cm² V^?1 s^?1 increasing to 62.8 cm² V^?1 s^?1 for graphitic-N-dominated film.

     

Experimental study of a combined biomass and solar energy-based fully grid-independent air-conditioning system

Clean Technologies and Environmental Policy - In this paper, a small-scale triple-hybrid air-conditioning system operated by biomass and solar energy resources is experimentally investigated....     

Temporal Variation of Energy Fluxes During Dry Season in Tropical Lowland Rice

Temporal variation of ‘surface energy balance’ was quantified on tropical lowland rice for 4 years (2013–2016). High response (10 Hz) eddy covariance system was used to estimate real time data on net radiation (NR), sensible heat (Hs), latent heat (LE), air and soil temperature. Annual, monthly, diurnal as well as phenological crop stage wise variation were analysed. Majority of radiation received from sun was partitioned into latent heat (LE, 44–73%) followed by soil heat (G, 13–42%) and sensible heat (Hs 3–16%) in dry cropping season. This was primarily due to presence of stagnant water in this ecology throughout the cropping period except few days during harvesting. Average Hs was negative in the month of April because of higher evapotranspiration during full grown crop at its reproductive stage as well as stagnant water in field. LE was the major contributor of energy balance and consistently increased from active tillering to grain filling stages then gradually decreased in harvesting. Hs contributing more at the initial stages of rice. Diurnal variation showed maximum Hs during 12:00 to 13:00 hours, whereas, highest LE and G were noticed during 13:00 and 11:30–12:00 hours, respectively. LE and G regressed well than Hs with air temperature and NR.     

Spin Transport Investigations in Bilayer Graphene

We study the spin-based electron transport properties in bilayer graphene with half-metallic ferromagnetic (HMF) CrO₂ electrodes. Out-of-plane bilayer graphene has been examined in this paper. A high magneto-resistance ratio (MR) of ～99% is obtained in the bilayer structure for a potential range of 0 to 0.8 V, after which MR drops because of the increase in spin-up current in the anti-parallel configuration at 1.2 V. High spin filtration of ～100% is obtained at all bias points. Transmission spectrum studies show that a large number of electronic states are present at the Fermi level in bilayer graphene, which would result in high current.     

Synthesis and characterization of Cu nanotubes and nanothreads by electrical arc evaporation

We report the formation and characterization of copper nanostructures, nanotubules and nanothreads, which were obtained by electrical arc evaporation of Cu electrodes under varied conditions of He ambience. Electrical arc evaporation was done with approximately 10 V and (approximately 50-100 A) DC current. The current was used in a pulse mode. The evaporated material was condensed on a formvar-coated Cu grid mounted on a liquid N2-cooled specimen holder. Transmission electron microscopy was employed to characterize the condensed materials. These investigations revealed that the condensed materials consisted of the mentioned nanostructures. Nanotubes and nanothreads are formed for a He pressure in the chamber corresponding to approximately 140 and approximately 500 torr, respectively. Extensive electron microscopic investigations showed that the diameter of the nanotubes varied from approximately 5 nm to approximately 50 nm and their length from 2 microns to 3 microns.     

Behavior of decomposition of rifampicin in the presence of isoniazid in the pH range 1-3

The extent of decomposition of rifampicin in the presence of isoniazid was determined in the pH range 1-3 at 37°C in 50 min, the mean stomach residence time. With increase in pH, the degradation initially increased from pH 1 to 2 and then decreased, resulting in a bell-shaped pH-decomposition profile. This showed that rifampicin degraded in the presence of isoniazid to a higher extent at pH 2, the maximum pH in the fasting condition, under which antituberculosis fixed-dose combination (FDC) products are administered. At this pH and in 50 min, rifampicin decomposed by ~ 34%, while the fall of isoniazid was 10%. The extent of decomposition for the two drugs was also determined in marketed formulations, and the values ranged between 13-35% and 4-11%, respectively. The extents of decomposition at stomach residence times of 15 min and 3 h were 11.94% and 62.57%, respectively, for rifampicin and 4.78% and 11.12%, respectively, for isoniazid. The results show that quite an extensive loss of rifampicin and isoniazid can occur as a result of interaction between them in fasting pH conditions. This emphasizes that antituberculosis FDC formulations, which contain both drugs, should be designed in a manner that the interaction of the two drugs is prevented when the formulations are administered on an empty stomach.     

Simplified Kernel Method for Flow to Large Diameter Wells

A computationally simple kernel method is proposed for obtaining drawdowns due to unsteady pumping of large diameter wells. The kernels can be worked out even on a hand-held calculator. The new method can also be used to obtain residual drawdowns. The new method yields results as good as those obtained using earlier methods.     

Role of circuit and logic simulators in EE curriculum

The experiences of the author in the use of four simulation packages in four different courses in an electrical engineering curriculum during the past four years are described. The simulators used were the commercially available SPICE and HILO and the home-grown EEPAK and APAP. The capabilities of the packages are briefly noted. The advantages and disadvantages of the use of simulators in education are discussed in some detail. It is concluded that, when one weighs the pros and cons of using computer simulation, the advantages far outweigh the disadvantages, and that the simulators play a positive role as long as they are kept subservient to the main goal of education, which is imparting knowledge and understanding of the subject.<>     

Dynamic content-page identification for media-rich websites

Knowledge of the information goal of users is critical in website design, analyzing the efficacy of such designs, and in ensuring effective user-access to desired information. Determining the information goal is complex due to the subjective and latent nature of user information needs. This challenge is further exacerbated in media-rich websites since the semantics of media-based information is context-based and emergent. A critical step in determining information goals lies in the identification of content pages. These are the pages which contain the information the user seeks. We propose a method to automatically determine the content pages by taking into account the organization of the web site, the media-based information content, as well as the influence of a specific user browsing pattern. Given a specific browsing pattern, in our method, putative content pages are identified as the pages corresponding to the local minima of page-content entropy values. For an (unknown) user information goal this intuitively corresponds to modeling the progressive transition of the user from pages with generic information to those with specific information. Experimental investigations on media rich sites demonstrate the effectiveness of the technique and underline its potential in modeling user information needs and actions in a media-rich web.     

Imperfect fluid cosmology with heat flow

We discuss spatially homogeneous and locally rotationally symmetric Bianchi type V cosmological models under the influence of both bulk and shear viscosity coefficients with heat flow. Some exact solutions of the Einstein field equations are presented by using a law of variation for the generalized Hubble parameter that yields a constant value of the deceleration parameter. The law also generates power-law and exponential forms of the average scale factor in terms of the cosmic time t. To get a complete solution, a linear relation between the shear viscosity and the expansion scalar has been assumed. The presence of viscous terms, however, does not change the fundamental nature of the initial singularity. The solutions presented here satisfy all necessary conditions for physical acceptability. The thermodynamical relations, entropy production and energy condition in viscous fluid model are studied in detail.