Wake Vortex Field Measurement Program at Memphis, Tennessee: Data Guide

Eliminating or reducing current restrictions in the air traffic control system due to wake vortex considerations would yield increased capacity, decreased delays, and cost savings. Current wake vortex separation standards are widely viewed as very conservative under most conditions. However, scientific uncertainty about wake vortex behavior under different atmospheric conditions remains a barrier to development of an adaptive vortex spacing system. The objective of the wake vortex field measurement efforts during December, 1994 and August, 1995 at Memphis, TN were to record wake vortex behavior for varying atmospheric conditions and types of aircraft. This effort is part of a larger effort by the NASA Langley Research Center to develop an Aircraft Vortex Spacing System (AVOSS) as an element of the Terminal Area Productivity (TAP) program. The TAP program is being performed in concert with the FAA Terminal Air Traffic Control Automation (TATCA) program and ATC Automation. Wake vortex behavior was observed using a mobile continuous-wave (CW) coherent laser Doppler radar (lidar) developed at Lincoln Laboratory. This lidar features a number of improvements over previous systems, including the first-ever demonstration of an automatic wake vortex detection and tracking algorithm

Diverse silver(I) coordination chemistry with cyclic selenourea ligands

The coordination chemistry of two selenourea ligands (SeIMes and SeIPr) towards silver(I) triflate and silver(I) nitrate was investigated. Two aggregation modes were observed in the solid state, strongly influenced by the size of the aromatic substituents on the ligand. With mesityl groups, selenium-bridged bimetallic motifs [AgX(SeIMes)]2 were obtained, while for the bulkier diisopropylphenyl groups ion-separated species of formulae [Ag(SeIPr)2]+[X]− were obtained. Recrystallization of [Ag(NO3)(SeIMes)]2 from hot methanol resulted in the formation of a unique coordination polymer featuring three silver environments. Characterization of the complexes by NMR spectroscopy and mass spectrometry suggested all complexes adopt the ionic aggregation mode in methanol solution.Natural Sciences and Engineering Research Council of Canada (Discovery Development Grant (DDG-2017-00041))https://pubs.rsc.org/en/content/articlelanding/2018/DT/C7DT04243D#!divAbstrac

S-layers at second glance? Altiarchaeal grappling hooks (hami) resemble archaeal S-layer proteins in structure and sequence

This is the final version of the article. Available from Frontiers Media via the DOI in this recordResearch on SM1-MSI was supported by the German Research Foundation (Deutsche Forschungsgemeinschaft), grant no. MO 1977/3-1 given to CM-E. AJP was supported by the German National Academic Foundation (Studienstiftung des deutschen Volkes)

Electrophilic Organoiridiunn(III) Pincer Complexes on Sulfated Zirconia for Hydrocarbon Activation and Functionalization

Single-site supported organometallic catalysts bring together the favorable aspects of homogeneous and heterogeneous catalysis while offering opportunities to investigate the impact of metal–support interactions on reactivity. We report a (dmPhebox)Ir(III) (dmPhebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) complex chemisorbed on sulfated zirconia, the molecular precursor for which was previously applied to hydrocarbon functionalization. Spectroscopic methods such as diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS), dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and X-ray absorption spectroscopy (XAS) were used to characterize the supported species. Tetrabutylammonium acetate was found to remove the organometallic species from the surface, enabling solution-phase analytical techniques in conjunction with traditional surface methods. Cationic character was imparted to the iridium center by its grafting onto sulfated zirconia, imbuing high levels of activity in electrophilic C–H bond functionalization reactions such as the stoichiometric dehydrogenation of alkanes, with density functional theory (DFT) calculations showing a lower barrier for β-H elimination. Catalytic hydrogenation of olefins was also facilitated by the sulfated zirconia-supported (dmPhebox)Ir(III) complex, while the homologous complex on silica was inactive under comparable conditions

A Film of Ones Own: The Animated Self-Portraits of Young Contemporary Female Animators

This article analyses animated self-portraits created by contemporary young and emerging women in animation, and elucidates significant differences between this new generation of women animators and previous ones. Through their animated self-portraits, the earlier animatrices explored their own identity as women and artists, developing new discourses and models for a subgenre that existed from the early days of cinema animation. But the animated female self-portrayal of the new generation comes closer to documentary and has more universal concerns, appealing to a wider audience and reaching theatrical distribution; Marjane Satrapi’s feature-length animation film Persepolis (2007) exemplifies this and is a focus of the article.Lorenzo Hernández, MC. (2010). A Film of Ones Own: The Animated Self-Portraits of Young Contemporary Female Animators. Animation. 5(1):73-90. doi:10.1177/1746847709358638S739051Satrapi, M. ( 2008) ‘ Persepolis: A State of Mind’, Literal. Latin American Voices, February: 44-7

Tensile Strength of Geological Discontinuities Including Incipient Bedding, Rock Joints and Mineral Veins

Geological discontinuities have a controlling influence for many rock-engineering projects in terms of strength, deformability and permeability, but their characterisation is often very difficult. Whilst discontinuities are often modelled as lacking any strength, in many rock masses visible rock discontinuities are only incipient and have tensile strength that may approach and can even exceed that of the parent rock. This fact is of high importance for realistic rock mass characterisation but is generally ignored. It is argued that current ISRM and other standards for rock mass characterisation, as well as rock mass classification schemes such as RMR and Q, do not allow adequately for the incipient nature of many rock fractures or their geological variability and need to be revised, at least conceptually. This paper addresses the issue of the tensile strength of incipient discontinuities in rock and presents results from a laboratory test programme to quantify this parameter. Rock samples containing visible, natural incipient discontinuities including joints, bedding, and mineral veins have been tested in direct tension. It has been confirmed that such discontinuities can have high tensile strength, approaching that of the parent rock. Others are, of course, far weaker. The tested geological discontinuities all exhibited brittle failure at axial strain less than 0.5 % under direct tension conditions. Three factors contributing to the tensile strength of incipient rock discontinuities have been investigated and characterised. A distinction is made between sections of discontinuity that are only partially developed, sections of discontinuity that have been locally weathered leaving localised residual rock bridges and sections that have been ‘healed’ through secondary cementation. Tests on bedding surfaces within sandstone showed that tensile strength of adjacent incipient bedding can vary considerably. In this particular series of tests, values of tensile strength for bedding planes ranged from 32 to 88 % of the parent rock strength (intact without visible discontinuities), and this variability could be attributed to geological factors. Tests on incipient mineral veins also showed considerable scatter, the strength depending upon the geological nature of vein development as well as the presence of rock bridges. As might be anticipated, tensile strength of incipient rock joints decreases with degree of weathering as expressed in colour changes adjacent to rock bridges. Tensile strengths of rock bridges (lacking marked discolouration) were found to be similar to that of the parent rock. It is concluded that the degree of incipiency of rock discontinuities needs to be differentiated in the process of rock mass classification and engineering design and that this can best be done with reference to the tensile strength relative to that of the parent rock. It is argued that the science of rock mass characterisation may be advanced through better appreciation of geological history at a site thereby improving the process of prediction and extrapolating properties

Upcycling Single-Use Polyethylene into High-Quality Liquid Products

Our civilization relies on synthetic polymers for all aspects of modern life; yet, inefficient recycling and extremely slow environmental degradation of plastics are causing increasing concern about their widespread use. After a single use, many of these materials are currently treated as waste, underutilizing their inherent chemical and energy value. In this study, energy-rich polyethylene (PE) macromolecules are catalytically transformed into value-added products by hydrogenolysis using well-dispersed Pt nanoparticles (NPs) supported on SrTiO3 perovskite nanocuboids by atomic layer deposition. Pt/SrTiO3 completely converts PE (Mn = 8000− 158,000 Da) or a single-use plastic bag (Mn = 31,000 Da) into high-quality liquid products, such as lubricants and waxes, characterized by a narrow distribution of oligomeric chains, at 170 psi H2 and 300 °C under solvent-free conditions for reaction durations up to 96 h. The binding of PE onto the catalyst surface contributes to the number averaged molecular weight (Mn) and the narrow polydispersity (Đ) of the final liquid product. Solidstate nuclear magnetic resonance of 13C-enriched PE adsorption studies and density functional theory computations suggest that PE adsorption is more favorable on Pt sites than that on the SrTiO3 support. Smaller Pt NPs with higher concentrations of undercoordinated Pt sites over-hydrogenolyzed PE to undesired light hydrocarbons