THE KAUST Repository is an initiative of the University Library to expand the impact of conference papers, technical reports, peer-reviewed articles, preprints, theses, images, data sets, and other research-related works of King Abdullah University of Science and Technology (KAUST). 

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  • Optical force decoration of 3D microstructures with plasmonic particles

    Donato, M. G.; Rajamanickam, Vijayakumar Palanisamy; Foti, A.; Gucciardi, P. G.; Liberale, Carlo; Maragò, O. M. (The Optical Society, 2018-10-12)
    Optical forces are used to push and aggregate gold nanorods onto several substrates creating surface-enhanced Raman scattering (SERS) active hot spots for Raman-based identification of proteins. By monitoring the increase of the protein SERS signal, we observe different aggregation times for different curvatures of the substrates. The slower aggregation dynamics on curved surfaces is justified by a simple geometrical model. In particular, this technique is used to decorate three-dimensional microstructures and to quickly realize hybrid micro/nanosensors for highly sensitive detection of biological material directly in a liquid environment.
  • Surrogate formulation for diesel and jet fuels using the minimalist functional group (MFG) approach

    Abdul Jameel, Abdul Gani; Naser, Nimal; Emwas, Abdul-Hamid M.; Sarathy, Mani (Elsevier BV, 2018-10-12)
    Surrogate fuels aim to reproduce real fuel combustion characteristics in order to enable predictive simulations and fuel/engine design. In this work, surrogate mixtures were formulated for three diesel fuels (Coryton Euro and Coryton US-2D certification grade and Saudi pump grade) and two jet fuels (POSF 4658 and POSF 4734) using the minimalist functional group (MFG) approach, a method recently developed and tested for gasoline fuels. The diesel and jet fuel surrogates were formulated by matching five important functional groups, while minimizing the surrogate components to two species. Another molecular parameter, called as branching index (BI), which denotes the degree of branching was also used as a matching criterion. The present works aims to test the ability of the MFG surrogate methodology for high molecular weight fuels (e.g., jet and diesel). 1H Nuclear Magnetic Resonance (NMR) spectroscopy was used to analyze the composition of the groups in diesel fuels, and those in jet fuels were evaluated using the molecular data obtained from published literature. The MFG surrogates were experimentally evaluated in an ignition quality tester (IQT), wherein ignition delay times (IDT) and derived cetane number (DCN) were measured. Physical properties, namely, average molecular weight (AMW) and density, and thermochemical properties, namely, heat of combustion and H/C ratio were also compared. The results show that the MFG surrogates were able to reproduce the combustion properties of the above fuels, and we demonstrate that fewer species in surrogates can be as effective as more complex surrogates. We conclude that the MFG approach can radically simplify the surrogate formulation process, significantly reduce the cost and time associated with the development of chemical kinetic models, and facilitate surrogate testing.
  • Differential diffusion effect on the stabilization characteristics of autoignited laminar lifted methane/hydrogen jet flames in heated coflow air

    Jung, Ki Sung; Kim, Seung Ook; Lu, Tianfeng; Chung, Suk-Ho; Lee, Bok Jik; Yoo, Chun Sang (Elsevier BV, 2018-10-10)
    The characteristics of autoignited laminar lifted methane/hydrogen jet flames in heated coflow air are numerically investigated using laminarSMOKE code with a 57-species detailed methane/air chemical kinetic mechanism. Detailed numerical simulations are performed for various fuel jet velocities, U0, with different hydrogen ratio of the fuel jet, RH, and the inlet temperature, T0. Based on the flame characteristics, the autoignited laminar lifted jet flames can be categorized into three regimes of combustion mode: the tribrachial edge flame regime, the Moderate or Intense Low-oxygen Dilution (MILD) combustion regime, and the transition regime in between. Under relatively low temperature and high hydrogen ratio (LTHH) conditions, an unusual decreasing liftoff height, HL, behavior with increasing U0 is observed, qualitatively similar to those of previous experimental observations. From additional simulations with modified hydrogen mass diffusivity, it is substantiated that the unusual decreasing HL behavior is primarily attributed to the high diffusive nature of hydrogen molecules. The species transport budget, autoignition index, and displacement speed analyses verify that the autoignited lifted jet flames are stabilized by autoignition-assisted flame propagation or autoignition depending on the combustion regime. Chemical explosive mode analysis (CEMA) identifies important variables and reaction steps for the MILD combustion and tribrachial edge flame regimes.
  • Predator Avoidance in the European Seabass After Recovery From Short-Term Hypoxia and Different CO2 Conditions

    Steckbauer, Alexandra; Díaz-Gil, Carlos; Alós, Josep; Catalán, Ignacio A.; Duarte, Carlos M. (Frontiers Media SA, 2018-10-09)
    Short-term hypoxia that lasts just a few days or even hours is a major threat for the marine ecosystems. The single effect of the human-induced levels of hypoxia and other anthropogenic impacts such as elevated pCO2 can reduce the ability of preys to detect their predators across taxa. Moreover, both processes, hypoxia and elevated pCO2, are expected to co-occur in certain habitats, but the synergic consequences of both processes and the ability of fish to recover remain unknown. To provide empirical evidence to this synergy, we experimentally evaluated the risk-taking behavior in juveniles of the European seabass (Dicentrachus labrax), an important commercial fisheries species after recovering from short-term hypoxia and different pH scenarios. The behavior of seabass juveniles was monitored in an experimental arena before and after the exposure to a simulated predator and contrasted to control fish (BACI design) (current levels of hypoxia and elevated pCO2) using a mechanistic function-valued modeling trait approach. Results revealed that fish recovering from elevated pCO2, alone or combined with hypoxia, presented less avoidance behavior in failing to seek refuge when a simulated predator was present in the arena compared to those exposed to control pCO2 levels. Our results show that recovery from short-term exposure to acidification and hypoxia was not synergistic and suggest that recovery from acidification takes longer than from short-term hypoxia treatment through a potential effect on the sensorial and hence behavioral capacities of fish.
  • Flexible Lightweight CMOS-Enabled Multisensory Platform for Plant Microclimate Monitoring

    Khan, Sherjeel M.; Shaikh, Sohail F.; Qaiser, Nadeem; Hussain, Muhammad Mustafa (Institute of Electrical and Electronics Engineers (IEEE), 2018-10-09)
    We report an ultralightweight flexible sensory platform using bare die CMOS chips having a light, temperature, and humidity sensor on a flexible polymer substrate. An application-specified integrated circuit designed and fabricated in a 0.35-μm process is used for signal acquisition, conditioning, and further transfer of data to a bare die microcontroller. The whole platform is powered by a bare die solid-state battery. This extremely lightweight (0.44 g), compact (3 x 1.5 cm²), flexible, and mostly transparent platform can be unobtrusively placed on a leaf of a plant to monitor microclimate conditions surrounding a plant for accurate plant growth monitoring. The latter is successfully demonstrated by placing the platform on a plant leaf and monitoring changing environmental conditions (light, temperature, and humidity) for a whole day.

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