Robust Hydrogen-Bonded Organic Framework with Four-Fold Interpenetration for Adsorptive Separation of C 2 H 6 /C 2 H 4 and Xe/Kr
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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Tuning the catalytic CO hydrogenation to straight- and long-chain aldehydes/alcohols and olefins/paraffins
Here, the catalytic CO hydrogenation is one of the most versatile large-scale chemical syntheses leading to variable chemical feedstock. While traditionally mainly methanol and long-chain hydrocarbons are produced by CO hydrogenation, here we show that the same reaction can be tuned to produce long-chain n-aldehydes, 1-alcohols and olefins, as well as n-paraffins over potassium-promoted CoMn catalysts. The sum selectivity of aldehydes and alcohols is usually >50 wt% whereof up to ~97% can be n-aldehydes. While the product slate contains ~60% n-aldehydes at /p CO =0.5, a 65/35% slate of paraffins/alcohols is obtained at a ratio of 9. A linear Anderson–Schulz–Flory behaviour, independent of the /p CO ratio, is found for the sum of C 4+ products. We advocate a synergistic interaction between a Mn 5 O 8 oxide and a bulk Co 2 C phase, promoted by the presence of potassium, to be responsible for the unique product spectra in our studies.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Genomic and functional analyses of fungal and bacterial consortia that enable lignocellulose breakdown in goat gut microbiomes
Abstract The herbivore digestive tract is home to a complex community of anaerobic microbes that work together to break down lignocellulose. These microbiota are an untapped resource of strains, pathways and enzymes that could be applied to convert plant waste into sugar substrates for green biotechnology. We carried out more than 400 parallel enrichment experiments from goat faeces to determine how substrate and antibiotic selection influence membership, activity, stability and chemical productivity of herbivore gut communities. We assembled 719 high-quality metagenome-assembled genomes (MAGs) that are unique at the species level. More than 90% of these MAGs are from previously unidentified herbivore gut microorganisms. Microbial consortia dominated by anaerobic fungi outperformed bacterially dominated consortia in terms of both methane production and extent of cellulose degradation, which indicates that fungi have an important role in methane release. Metabolic pathway reconstructions from MAGs of 737 bacteria, archaea and fungi suggest that cross-domain partnerships between fungi and methanogens enabled production of acetate, formate and methane, whereas bacterially dominated consortia mainly produced short-chain fatty acids, including propionate and butyrate. Analyses of carbohydrate-active enzyme domains present in each anaerobic consortium suggest that anaerobic bacteria and fungi employ mostly complementary hydrolytic strategies. The division of labour among herbivore anaerobes to degrade plant biomass could be harnessed for industrial bioprocessing.
59 BASIC BIOLOGICAL SCIENCES↗
Supramolecular gel-assisted synthesis of double shelled Co@CoO@N-C/C nanoparticles with synergistic electrocatalytic activity for the oxygen reduction reaction
Investigating active, stable, and low-cost materials for the oxygen reduction reaction is one of the key challenges in fuel-cell research. In this work, we describe the formation of N-doped carbon shell coated Co@CoO nanoparticles supported on Vulcan XC-72 carbon materials (Co@CoO@N–C/C) based on a simple supramolecular gel-assisted method. The double-shelled Co@CoO@N–C/C core–shell nanoparticles exhibit superior electrocatalytic activities for the oxygen reduction reaction compared to N-doped carbon and cobalt oxides, demonstrating the synergistic effect of the hybrid nanomaterials. Notably, the Co@CoO@N–C/C nanoparticles give rise to a comparable four-electron selectivity, long-term stability, and high methanol tolerance; all show a multi-fold improvement over the commercial Pt/C catalyst. As a result, the progress is of great importance in exploring advanced non-precious metal-based electrocatalysts for fuel cell applications.
36 MATERIALS SCIENCE↗
High performance aliphatic-heterocyclic benzyl-quaternary ammonium radiation-grafted anion-exchange membranes
Here, anion-exchange membranes (AEM) containing saturated-heterocyclic benzyl-quaternary ammonium (QA) groups synthesised by radiation-grafting onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films are reported. The relative properties of these AEMs are compared with the benchmark radiation-grafted ETFE- g -poly(vinylbenzyltrimethylammonium) AEM. Two AEMs containing heterocyclic-QA head groups were down-selected with higher relative stabilities in aqueous KOH (1 mol dm –3 ) at 80 °C (compared to the benchmark): these 100 μm thick (fully hydrated) ETFE- g -poly(vinylbenzyl- N -methylpiperidinium)- and ETFE- g -poly(vinylbenzyl- N -methylpyrrolidinium)-based AEMs had as-synthesised ion-exchange capacities (IEC) of 1.64 and 1.66 mmol g –1 , respectively, which reduced to 1.36 mmol dm –3 (ca. 17–18% loss of IEC) after alkali ageing (the benchmark AEM showed 30% loss of IEC under the same conditions).
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
First-principles study of the defect-activity and optical properties of FAPbCl 3
With promising solar cell applications, organic–inorganic lead halide perovskites belong to a novel and rapidly developing class of semiconducting materials. Unlike its well-investigated iodide counterparts, formamidinium lead chloride (FAPbCl 3 ) is a much less studied perovskite that shows superior stability and surprisingly high selectivity and sensitivity towards certain gas analytes. The origin of the sensing ability of this perovskite material can be traced to its high defect tolerance and the existence of some defects which act as the “lock” to a certain gas analyte's “key”. In this work, we deepen the understanding of this proven perovskite sensor through first-principles computational study of its defect formation energies, charge transition energies, and optical properties. These studies are done with the widely used GGA exchange–correlation functional PBE and the newer meta-GGA functional SCAN, both incorporating the Grimme's D3 dispersion correction. Additionally, we also consider experimental conditions and the effect of temperature on electron screening in the simulations, which demonstrates that screening is particularly important when considering high oxidation states of the defects. We also note the importance of antisites in the Fermi Pinning as well as the importance of FA disorder, which are previously unreported insights.
36 MATERIALS SCIENCE↗
Combined hydrogen and lithium beam emission spectroscopy observation system for Korea Superconducting Tokamak Advanced Research
A novel beam emission spectroscopy observation system was designed, built, and installed onto the Korea Superconducting Tokamak Advanced Research tokamak. The system is designed in a way to be capable of measuring beam emission either from a heating deuterium or from a diagnostic lithium beam. The two beams have somewhat complementary capabilities: edge density profile and turbulence measurement with the lithium beam and two dimensional turbulence measurement with the heating beam. Two detectors can be used in parallel: a CMOS camera provides overview of the scene and lithium beam light intensity distribution at maximum few hundred Hz frame rate, while a 4 × 16 pixel avalanche photo-diode (APD) camera gives 500 kHz bandwidth data from a 4 cm × 16 cm region. The optics use direct imaging through lenses and mirrors from the observation window to the detectors, thus avoid the use of costly and inflexible fiber guides. Remotely controlled mechanisms allow adjustment of the APD camera’s measurement location on a shot-to-shot basis, while temperature stabilized filter holders provide selection of either the Doppler shifted deuterium alpha or lithium resonance line. The capabilities of the system are illustrated by measurements of basic plasma turbulence properties.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Orientation control and domain structure analysis of {100}-oriented epitaxial ferroelectric orthorhombic HfO{sub 2}-based thin films
Orientation control of {100}-oriented epitaxial orthorhombic 0.07YO{sub 1.5}-0.93HfO{sub 2} films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal–orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO{sub 2}-based ferroelectric films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O{sub 3} and BiFeO{sub 3}.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Formation of Complex Spin Textures in Thermally Demagnetized La 0.7 Sr 0.3 Mn O 3 Artificial-Spin-Ice Structures
Artificial spin ices (ASIs) have traditionally been designed such that each nanomagnet possesses a single-domain magnetic configuration that is assumed to be minimally perturbed by interisland dipolar interactions. Using x-ray photoemission electron microscopy to perform magnetic domain imaging, we study thermally demagnetized La 0.7 Sr 0.3 MnO 3 -based brickwork ASI arrays and showed that complex spin textures (CSTs) can be stabilized through an appropriate selection of nanoisland width and interisland spacing. While the width dependence can be explained through the dominance of shape anisotropy in isolated nanoislands, the ASIs we investigate demonstrate a complex dependence on both the nanoisland width and interisland spacing. Micromagnetic simulations reveal that interisland dipolar interactions play a role in the formation of CSTs, which are composed of single- and double-vortex states. Furthermore, energy analysis of the simulations provides an understanding of the system energetics that arises from a delicate balance between intraisland effects (i.e., shape anisotropy and exchange energy) and interisland effects (i.e., dipolar interactions between nearest-neighbor nanoislands).
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Three-Phase Power Converter-Based Real-Time Synchronous Generator Emulation
This paper develops a synchronous generator emulator by using a three-phase voltage source converter for transmission level power system testing. Different interface algorithms are compared, and the voltage type ideal transformer model is selected considering accuracy and stability. At the same time, closed-loop voltage control with current feed-forward is proposed to decrease the emulation error. The emulation is then verified through two different ways. First, the output waveforms of the emulator in experiments are compared with the simulation under the same condition. Second, a transfer function perturbation-based error model is obtained and redefined as the relative error for the amplitude and phase between the emulated and the target system over the frequency range of interest. Finally, the major cause of the error is investigated through a quantitative analysis of the error with varying parameters.
24 POWER TRANSMISSION AND DISTRIBUTION↗
A customized MOF-polymer composite for rapid gold extraction from water matrices
With the fast-growing accumulation of electronic waste and rising demand for rare metals, it is compelling to develop technologies that can promotionally recover targeted metals, like gold, from waste, a process referred to as urban mining. Thus, there is increasing interest in the design of materials to achieve rapid, selective gold capture while maintaining high adsorption capacity, especially in complex aqueous-based matrices. Here, a highly porous metal-organic framework (MOF)–polymer composite, BUT-33–poly(para-phenylenediamine) (PpPD), is assessed for gold extraction from several matrices including river water, seawater, and leaching solutions from CPUs. BUT-33–PpPD exhibits a record-breaking extraction rate, with high Au3+ removal efficiency (>99%) within seconds (less than 45 s), a competitive capacity (1600 mg/g), high selectivity, long-term stability, and recycling ability. Furthermore, the high porosity and redox adsorption mechanism were shown to be underlying reasons for the material’s excellent performance. Given the accumulation of recovered metallic gold nanoparticles inside, the material was also efficiently applied as a catalyst.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Fact Sheet: Polymer-Based Carbon Dioxide Capture Membrane Systems
To develop and demonstrate polymer-based membrane structures, deployment platforms, and sealing technologies that achieve the critical combination of high selectivity, high permeability, chemical stability, and mechanical stability all at elevated temperatures (>150°C) and packaged in a scalable, economically viable, high area density system amenable to incorporation into an integrated gasification combined cycle (IGCC) plant for pre-combustion carbon dioxide (CO2) capture.
Energy Conservation, Consumption, & Utilization(32↗
Bimetallic Nanocatalysts in Mesoporous Silica for Hydrogen Production from Coal-Derived Fuels
In steam reforming reactions (SRRs) of alkanes and alcohols to produce H 2 , noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N 2 adsorption, and Transmission electron microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m 2 /g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean Transportation Fuels”; Hu, Y., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2011.)
08 HYDROGEN↗
Molecular level control of nanoscale composition and morphology: Toward photocatalytic nanocomposites for solar-to-chemical energy conversion of biomass
Understanding the factors influencing nanocrystal formation is a challenge yet to be realized. In comparison to the large number of studies on nanocrystal synthesis and their applications, the number of studies on the effect of the precursor chemistry on nanocrystal composition and shape remains low. Although photochemical fabrication of metalsemiconductor nano-heterostructures is reported in literature, control over the free particle formation and the site of metal deposition have not been achieved. Moreover, utilization of metal- semiconductor nano-heterostructures in photocatalytic reactions other than water splitting is hardly explored. In this thesis, we studied the effect of chalcogenide precursor reactivity on the composition, morphology and the axial anisotropy of cadmiumchalcogenide nanocrystals. We also investigated the influence of the irradiation wavelength in synthesizing metal-semiconductor nano-heterostructures. Finally, we showed that metal semiconductor nano-heterostructures can be used as a photocatalyst for alcohol dehydrogenation reactions. We explored the pathways for the formation of Pt and Pd nanoparticles on CdS and CdS{sub 0.4}Se{sub 0.6} nanorods. This study revealed that the wavelength of irradiation is critical to control free-standing vs. bound metal (Pt and Pd) nanoparticles to semiconductor. Additionally, we observed that metal photodeposition occurs on specific segments of axially anisotropic, compositionally graded CdS0.4Se0.6 nanorods due to the band-gap differential between their nano-domains. We used semiconductor-metal heterostructures for sunlightdriven dehydrogenation and hydrogenolysis of benzyl alcohol. Heterostructure composition dictates activity (turnovers) and product distribution. A few metal (Pt, Pd) islands on the semiconductor surface significantly enhance activity and selectivity and also greatly stabilize the semiconductor against photoinduced etching and degradation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Astronomy Spacelab payloads
Preliminary analyses of four typical Spacelab astronomy payloads have been completed. The payloads consist of instrumentation recommended by NASA and other scientists for early Shuttle missions. Design concepts have been prepared and compatibility with Shuttle and Spacelab verified. Mission parameters that meet payload requirements and efficiently utilize Shuttle resources have been selected. Integrated pointing and stabilization and command and data-handling system concepts have been developed. The results of all these activities indicate that productive astronomy missions can be carried out with Shuttle and Spacelab systems.
Ott, R.↗
A stochastic model of cumulus clumping
Observations show that cumulus clouds often occur in long-lived mesoscale groups, or clumps. Five possible explanations of clumping are surveyed. The 'mutual protection hypothesis,' that clumps occur because cumulus clouds create and maintain, in their near environments, relatively favorable conditions for the development of succeeding clouds, is examined at length. This idea is tested through the use of a simple time-dependent model in which clouds, triggered at randomly selected locations, tend to stabilize their environment in the face of a prescribed constant forcing. Results show that clumping occurs when the cloud-induced stabilization rate is strongest at an intermediate distance from a cloud, and that it does not occur when the stabilization rate decreases monotonically away from a cloud.
Randall, D. A.↗
Wind-tunnel investigation of longitudinal and lateral-directional stability and control characteristics of a 0.237-scale model of a remotely piloted research vehicle with a thick, high-aspect-ratio supercritical wing
A 0.237-scale model of a remotely piloted research vehicle equipped with a thick, high-aspect-ratio supercritical wing was tested in the Langley 8-foot transonic tunnel to provide experimental data for a prediction of the static stability and control characteristics of the research vehicle as well as to provide an estimate of vehicle flight characteristics for a computer simulation program used in the planning and execution of specific flight-research mission. Data were obtained at a Reynolds number of 16.5 x 10 to the 6th power per meter for Mach numbers up to 0.92. The results indicate regions of longitudinal instability; however, an adequate margin of longitudinal stability exists at a selected cruise condition. Satisfactory effectiveness of pitch, roll, and yaw control was also demonstrated.
Byrdsong, T. A.↗
Stabilized Aluminum Titanate
Stable, potentially-inexpensive, cubic crystalline alpha aluminum titanate that shows no phase change to 1,700 K used in heat exchangers. Particular stabilizing species must be selected with careful attention to crystal dimensions and bond angles of alpha and beta phases of aluminum titanate.
Schroeder, J. E.↗