1,575 research outputs found
Use of co-solvents in hydrothermal liquefaction (HTL) of microalgae
This study reviewed and summarized the literature regarding the use of alcohols during hydrothermal liquefaction (HTL) of algal biomass feedstocks. The use of both pure alcohols and alcohol-water co-solvents were considered. Based upon this review, laboratory experiments were conducted to investigate the impacts of different alcohol co-solvents (ethanol, isopropanol, ethylene glycol, and glycerol) on the HTL treatment of a specific saltwater microalga (Tetraselmis sp.) at two temperatures: 300 ?C and 350 ?C. Based on their performance, two co-solvents, isopropanol and ethylene glycol, were selected to explore the effects of varying solvent concentrations and reaction temperatures on product yields and biocrude properties. The type and amount of added alcohol did not significantly affect the biocrude yield or composition. Biocrude yields were in the range of 30-35%, while a nearly constant yield of 21% insoluble products was observed, largely resulting from ash constituents within the algal feedstock. The benefits of using alcohol co-solvents (especially isopropanol) were the reduced viscosity of the biocrude products and reduced rates of viscosity increase with biocrude aging. These effects were attributed mainly to the physical properties of the co-solvent mixtures (solubility, polarity, density, etc.) rather than chemical processes. Under the reaction conditions used, there was no evidence that the co-solvents participated in biocrude production by means of hydrogen donation or other chemical processes. Recovery and recycling of the co-solvent present various challenges, depending upon the type and amount of the co-solvent that is used. For example, glycol solvents are recovered nearly completely within the aqueous product stream, whereas simple alcohols are partitioned between the biocrude and aqueous product streams. In commercial applications, the slight benefits provided by the use of co-solvents must be balanced by the challenges of co-solvent recovery and recycling. - 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).This research received funding from the Qatar National Priorities Research Program (NPRP grant, grant number 8-646-4-727 from the Qatar National Research Fund).Scopu
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Guidance in the human–machine analytics process
In this paper, we list the goals for and the pros and cons of guidance, and we discuss the role that it can play not only in key low-level visualization tasks but also the more sophisticated model-generation tasks of visual analytics. Recent advances in artificial intelligence, particularly in machine learning, have led to high hopes regarding the possibilities of using automatic techniques to perform some of the tasks that are currently done manually using visualization by data analysts. However, visual analytics remains a complex activity, combining many different subtasks. Some of these tasks are relatively low-level, and it is clear how automation could play a role—for example, classification and clustering of data. Other tasks are much more abstract and require significant human creativity, for example, linking insights gleaned from a variety of disparate and heterogeneous data artifacts to build support for decision making. In this paper, we outline the potential applications of guidance, as well as the inputs to guidance. We discuss challenges in implementing guidance, including the inputs to guidance systems and how to provide guidance to users. We propose potential methods for evaluating the quality of guidance at different phases in the analytic process and introduce the potential negative effects of guidance as a source of bias in analytic decision making
A Fully Tunable Single-Walled Carbon Nanotube Diode
We demonstrate a fully tunable diode structure utilizing a fully suspended
single-walled carbon nanotube (SWNT). The diode's turn-on voltage under forward
bias can be continuously tuned up to 4.3 V by controlling gate voltages, which
is ~6 times the nanotube bandgap energy. Furthermore, the same device design
can be configured into a backward diode by tuning the band-to-band tunneling
current with gate voltages. A nanotube backward diode is demonstrated for the
first time with nonlinearity exceeding the ideal diode. These results suggest
that a tunable nanotube diode can be a unique building block for developing
next generation programmable nanoelectronic logic and integrated circuits.Comment: 14 pages, 4 figure
The children's brain tumor network (CBTN) - Accelerating research in pediatric central nervous system tumors through collaboration and open science
Pediatric brain tumors are the leading cause of cancer-related death in children in the United States and contribute a disproportionate number of potential years of life lost compared to adult cancers. Moreover, survivors frequently suffer long-term side effects, including secondary cancers. The Children's Brain Tumor Network (CBTN) is a multi-institutional international clinical research consortium created to advance therapeutic development through the collection and rapid distribution of biospecimens and data via open-science research platforms for real-time access and use by the global research community. The CBTN's 32 member institutions utilize a shared regulatory governance architecture at the Children's Hospital of Philadelphia to accelerate and maximize the use of biospecimens and data. As of August 2022, CBTN has enrolled over 4700 subjects, over 1500 parents, and collected over 65,000 biospecimen aliquots for research. Additionally, over 80 preclinical models have been developed from collected tumors. Multi-omic data for over 1000 tumors and germline material are currently available with data generation for > 5000 samples underway. To our knowledge, CBTN provides the largest open-access pediatric brain tumor multi-omic dataset annotated with longitudinal clinical and outcome data, imaging, associated biospecimens, child-parent genomic pedigrees, and in vivo and in vitro preclinical models. Empowered by NIH-supported platforms such as the Kids First Data Resource and the Childhood Cancer Data Initiative, the CBTN continues to expand the resources needed for scientists to accelerate translational impact for improved outcomes and quality of life for children with brain and spinal cord tumors
Spin-liquid-like state in a square lattice antiferromagnet
Collective behavior of spins, frustration-induced strong quantum fluctuations
and subtle interplay between competing degrees of freedom in quantum materials
can lead to correlated quantum states with fractional excitations that are
essential ingredients for establishing paradigmatic models and have immense
potential for quantum technologies. Quenched randomness is a new paradigm in
elucidating the emergence of spin-liquidlike states in geometrically frustrated
magnets. Herein, we report magnetization, specific heat, electron spin
resonance, and muon spin resonance studies on a 3d-electron-based square
lattice antiferromagnet Sr3CuTa2O9. In this material, S = 1/2 Cu2+
nearest-neighbor ions constitute a two-dimensional square lattice. The negative
value of Curie-Weiss temperature, obtained from the Curie-Weiss fit of
high-temperature magnetic susceptibility data indicates the presence of
antiferromagnetic interaction between Cu2+ moments. Specific heat data show the
absence of long-range magnetic ordering down to 64 mK despite a reasonably
strong exchange interaction between Cu2+ spins as reflected from a Curie-Weiss
temperature of -27 K. The power-law behavior and the data collapse of specific
heat and magnetization data evince the emergence of a random-singlet state in
Sr3CuTa2O9. The power-law-like spin auto-correlation function and the data
collapse of muon polarization asymmetry with longitudinal field dependence of
t/({\mu}0H){\gamma} further support credence to the presence of a
randomness-induced liquid-like state. Our results suggest that randomness
induced by disorder is a viable route to realize quantum spin liquid-like state
in this square lattice antiferromagnet
Communication: In search of four-atom chiral metal clusters
A combined study utilizing anion photoelectron spectroscopy and density functional theory was conducted to search for four-atom, chiral, metal, and mostly metal clusters. The clusters considered were AuCoMnBi−/0, AlAuMnO−/0, AgMnOAl−/0, and AuAlPtAg−/0, where the superscripts, −/0, refer to anionic and neutral cluster species, respectively. Based on the agreement of experimentally and theoretically determined values of both electron affinities and vertical detachment energies, the calculated cluster geometries were validated and examined for chirality. Among both anionic and neutral clusters, five structures were identified as beingchiral
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Ultrafast X-ray Studies of Structural Dynamics at SLAC
The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements demonstrate that the initial stage of crystal disordering results from inertial motion on a laser softened potential energy surface. These inertial dynamics dominate for the first half picosecond following laser excitation, indicating that interatomic forces minimally influence atomic excursions from the equilibrium lattice positions, even for motions in excess of an {angstrom}. This also indicates that the atoms disorder initially without losing memory of their lattice reference
Effect of different levels of alpha tocopherol on performance traits, serum antioxidant enzymes, and trace elements in Japanese quail ( Coturnix coturnix japonica ) under low ambient temperature
A comparison of product yields and inorganic content in process streams following thermal hydrolysis and hydrothermal processing of microalgae, manure and digestate
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