Luminescent compounds obtained from the thermal reaction of citric acid and urea have been studied and utilized in different applications in the past few years. The identified reaction products range...
We present gray gas general circulation model (GCM) simulations of the tidally locked mini-Neptune GJ 1214b. On timescales of 1,000-10,000 Earth days, our results are comparable to previous studies of the same planet, in the sense that they all exhibit two off-equatorial eastward jets. Over much longer integration times (50,000-250,000 Earth days) we find a significantly different circulation and observational features. The zonal-mean flow transitions from two off-equatorial jets to a single wide equatorial jet that has higher velocity and extends deeper. The hot spot location also shifts eastward over the integration time. Our results imply a convergence time far longer than the typical integration time used in previous studies. We demonstrate that this long convergence time is related to the long radiative timescale of the deep atmosphere and can be understood through a series of simple arguments. Our results indicate that particular attention must be paid to model convergence time in exoplanet GCM simulations, and that other results on the circulation of tidally locked exoplanets with thick atmospheres may need to be revisited.Mark S Marley and Tyler D Robinson. On the cool side: Modeling the atmospheres of brown dwarfs and giant planets.
replace toxic, expensive, or conflict materials with environmentally and socially more benign CNMs. Therefore, they are still considered promising candidates for a range of future applications in electronics, optoelectronics, or catalytic systems. Laser-fabrication methods have been investigated as fast, energy-saving, low-cost, and precise material processing techniques in both science and industry and even a new "age of photon-driven materials manufacturing" has been prognosed. [5] In industry, laser-processing techniques are mainly used for cutting, welding, cladding, or surface processing. [6] It allows for high-precision materials modifications with unprecedented accuracy, not only spatially but also temporally, which is of particular interest for the manufacturing of future small-scale electronic and photonic products. Also direct laser-induced materials synthesis has become an active field of research. For example, laser-induced ablation of graphite, discovered in the 1990s, is commonly used for the targeted synthesis of CNMs. [7,8] Highpower laser pulses hit a graphite target and create a carbon plasma above the surface, which reacts to crystalline nanocarbons. These laser-assisted synthesis methods differ from conventional thermal methods in the reaction timescales. Heat transfer within micro-or milliseconds allows for reactions different to conventional heating methods. Moreover, the precise spatial control with nano-to micrometer resolutions allows also for the fine patterning of materials. Generally, laser-patterning describes the micro-structuring of organic materials like polymers or plastics by evaporating material from their surface. [9] Directed 2D-film patterning by laser-induced material conversion evolved in the past years as a new synthetic fabrication method. [10] In particular, the uncomplicated access to laser-assisted patterning of graphene oxide and their relatives has given the field a significant push. [11-18] In most cases, graphene is produced by laser-induced reduction of graphene oxide (GO). Another famous laser-patternable material is polyimide (PI), which carbonizes at high temperatures. [19-21] Vast research efforts have been conducted on the characterization and application of laser-patterned GO or PI films. [22-24] However, the starting materials used are rather expensive and the modification of the resulting materials properties is limited since the starting materials are polymeric. Other materials could be used as precursor like paper or wood but without the possibility of choosing the initial substrate. [25] A precursor ink for carbon laser-patterning is developed using inexpensive, naturally abundant molecular compounds, namely citric acid and urea, and used to fine-print conductive carbon circuits on a flexible substrate. The precursor in the ink consists of organic nanoparticles obtained from the thermal treatment of citric acid and urea. This precursor is thoroughly characterized chemically and structurally. A simple recipe for the ink is then described for the creation...
Carbon laser-patterning (CLaP) is emerging as a new tool for the precise and selective synthesis of functional carbon-based materials for on-chip applications. The aim of this work is to demonstrate the applicability of laser-patterned nitrogen-doped carbon (LP-NC) for resistive gas-sensing applications. Films of pre-carbonized organic nanoparticles on polyethylenetherephthalate are carbonized with a CO 2 -laser. Upon laser-irradiation a compositional and morphological gradient in the films is generated with a carbon content of 92% near the top surface. The specific surface areas of the LP-NC are increased by introducing sodium iodide (NaI) as a porogen. Electronic conductivity and surface area measurements corroborate the deeper penetration of the laser-energy into the film in the presence of NaI. Furthermore, impregnation of LP-NC with MoC 1−x (<10 nm) nanoparticles is achieved by addition of ammonium heptamolybdate into the precursor film. The resulting dopingsensitive nano-grain boundaries between p-type carbon and metallic MoC 1−x lead to an improvement of the volatile organic compounds sensing response of ΔR/R 0 = −3.7% or −0.8% for 1250 ppm acetone or 900 ppm toluene at room temperature, respectively, which is competitive with carbon-based sensor materials. Further advances in sensitivity and in situ functionalization are expected to make CLaP a useful method for printing selective sensor arrays.
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