Trends for Outer Disk Profiles

The surface-brightness profiles of galaxy disks fall into three main classes, based on whether they are simple exponentials (Type I), bend down at large radii (Type II, "truncations") or bend up at large radii (Type III, "antitruncations"). Here, we discuss how the frequency of these different profiles depends on Hubble type, environment, and the presence or absence of bars; these trends may herald important new tests for disk formation models.Comment: LaTeX, 2 pages, 1 EPS figure, uses modified newpasp.sty (included). To appear in Formation and Evlution of Galaxy Disks, eds. J.G. Funes and E.M. Corsin

Cyclometallated Compounds of Palladium(ii), Rhodium(iii), and Iridium(iii).

A number of new complex compounds of palladium, gold, rhodium, iridium, and platinum have been synthesized and characterized. The organic ligands used in the preponderance of reactions involve some nitrogen heterocycle such as 2-arylpyridines, 2,6-diarylpyridines, benzo{h}quinoline, and caffeine. In most cases, the organic ligand underwent an intramolecular metallation (designated orthometallation or more generally cyclometallation ) with subsequent formation of a chelate ring containing a covalent metal to carbon bond. The effect of varying the substituents on the aryl moiety of the 2-arylpyridines supported the hypothesis that after initial N-complexation, the 2-position of the aryl nucleus experiences an electrophilic attack by the palladium atom. Several different palladium starting materials were used and it was found that: (a) Pd(acetylacetonate)(,2) did not react; (b) PdCl(,2)(C(,6)H(,5)CN)(,2) did not metallate, but did give a 2:1 (ligand-to-metal) adduct; and (c) both PdCl(,4)(\u272-) and Pd(CH(,3)COO)(,2) gave the desired cyclometallated products. Palladium(II) acetate has proven to be a more useful starting material than the tetrachloropalladata, since the resulting acetato-bridged dimers, unlike the chloro-bridged dimers, are soluble in polar organic solvents. Reactions of gold in such forms as AuCl(,4)(\u27-), (C(,6)H(,5))(,3)PAuCl, and dichloro-(mu)-1,2-bis(diphenylphosphino)ethanedigold(I) failed to produce any cyclometallated products under a broad assortment of conditions. Only compounds containing 1:1 (ligand to metal) adducts were formed. Occasionally, reduction to metallic gold occurred. Both rhodium and iridium formed biscyclometallated products containing two chelated rings per six-coordinated trivalent metal atom. In contrast to the four-coordinate palladium(II) chlorobridged dimers, the chloro-bridged dimers of rhodium and iridium were conveniently soluble in organic solvents. Platinum formed a compound which was analogous to those of the palladium chloro-bridged dimers. Detailed high resolution (\u271)H NMR studies (200 MHz) showed that cyclometallation did occur on the aryl nucleus of the 2-arylpyridines. The 6-heteroaryl protons and those \u27ortho\u27 to the metal-carbon bond are both shifted from the free ligand position. Depending on the metal, the shifts are either up- or downfield. These shifts can be explained by either through-space interactions of overlying aromatic rings and/or through-bond (metal-to-ligand) effects. The (\u271)H NMR spectra of these biscyclometallated rhodium and iridium complexes have established a trans-nitrogen octahedral structure for all of these d(\u276) compounds. Both acetato- and chloro-bridged dimers react with certain ligands to give mononuclear complexes containing the intact cyclometallated ligand. (\u271)H NMR studies of palladium and rhodium complexes containing diethyldithiocarbamate and 2-arylpyridines as chelating ligands strongly suggest that in the d(\u278) palladium compound there is metal-to-ligand back bonding whereas in the d(\u276) rhodium compound no such bonding occurs. Furthermore, in the former complex the methyl groups are found to be in non-equivalent sites while the methylene protons are in equivalent sites. The reverse is true for the latter (Rh) complex. These observations are explained by the different structures of the Pd and Rh complexes, but more importantly by different metal-ligand bonding to both the arylpyridine and the dtc ligands. The nitrogen of the dtc ligand appears to be sp(\u273) in the Rh complex and closer to sp(\u272) in the Pd complex. Single crystal X-ray determinations have confirmed that metallation of an aryl ring of both 2-arylpyridines and 2,6-diarylpyridines has occurred

The Outer Structure of Galactic Disks: Connections Between Bars, Disks, and Environments

Surface-brightness profiles for early-type (S0-Sb) disks exhibit three main classes (Type I, II, and III). Type II profiles are more common in barred galaxies, and most of the time appear to be related to the bar's Outer Lindblad Resonance. Roughly half of barred galaxies in the field have Type II profiles, but almost none in the Virgo Cluster do; this might be related to ram-pressure stripping in clusters. A strong \textit{anti}correlation is found between Type III profiles ("antitruncations") and bars: Type III profiles are most common when there is no bar, and least common when there is a strong bar.Comment: LaTeX, 4 pages, 2 EPS figures, uses modified newpasp.sty (included). To appear in Pathways through an Eclectic Universe, eds. J. H. Knapen, T. J. Mahoney, & A. Vazdeki

Benchmarking Mentoring Practices for Effective Teaching of Mathematics and Science

Pre-service mathematics and science teachers’ perceptions of their mentoring experiences were investigated using the five factor model of mentoring practices as a lens through which mentoring practices can be benchmarked for improvement. The Mentoring for Effective Teaching instrument was used to collect data from 68 preservice mathematics and science teachers on school placements in two Local Education Authorities (LEAs) in the South East region of England. The results of the data analysis indicate that mentors in the two LEAs overwhelmingly exhibit personal attributes for effective mentoring, provide adequate mentoring in pedagogical knowledge development, model effective teaching and professional practices and provide effective feedback to pre-service teachers. Yet, the results also indicate mentors did not provide adequate mentoring on systems requirements in relation to the national curriculum and school policies

Process for Sustainably Sourced 2,5 Furan Dicarboxylic Acid

Currently, there is a significant market for terephthalic acid (TPA)--a precursor for the ubiquitous plastic polymer polyethylene terephthalate (PET). As consumer preferences swing to more environmentally-friendly products, sustainable plastics, such as polyethylene furanoate (PEF), become more widely desired. In this project, the authors suggest a process for the synthesis of 2,5-Furandicarboxylic acid (FDCA), a diacid used in the synthesis of PEF, through a multi-step procedure following current industrial practices for TPA oxidation and patents from three sources: Synvina, a joint venture between Archer Daniels Midland (ADM) Company and DuPont Industrial Biosciences (DuPont), and Eastman. The first step of the process involves the isomerization of high fructose corn syrup (HFCS) to increase the syrup’s concentration of fructose. This fructose-rich sugar mixture is then dehydrated into hydroxymethylfurfural (HMF). The HMF is oxidized with a Co(CH3COOH)2-Mn(CH3COOH)2-HBr catalyst in acetic acid to produce FDCA. This crude FDCA product is then sent to a crystallizer where its FDCA-containing stream is sent to a final purification step beyond the scope of this project statement. The process detailed here is unprofitable on a yearly basis and would require an FDCA price premium of 422% over TPA, its direct competitor. Fundamentally, the high price of HFCS, and the large amount of HFCS needed to produce FDCA, makes this project unprofitable. Three suggestions are recommended to increase the profitability of the project, focusing HFCS as a feedstock. First, we suggest a project to be sponsored to investigate the separation of glucose from polyethylene glycol, a solvent in this process. Second, we consider the usage of a less refined, lower priced source of fructose. Third, we consider the usage of metal salts in situ with the dehydration reactor in the process, to achieve further isomerization of glucose to fructose

Incentive Engineering for Concurrent Games

We consider the problem of incentivising desirable behaviours in multi-agent systems by way of taxation schemes. Our study employs the concurrent games model: in this model, each agent is primarily motivated to seek the satisfaction of a goal, expressed as a Linear Temporal Logic (LTL) formula; secondarily, agents seek to minimise costs, where costs are imposed based on the actions taken by agents in different states of the game. In this setting, we consider an external principal who can influence agents' preferences by imposing taxes (additional costs) on the actions chosen by agents in different states. The principal imposes taxation schemes to motivate agents to choose a course of action that will lead to the satisfaction of their goal, also expressed as an LTL formula. However, taxation schemes are limited in their ability to influence agents' preferences: an agent will always prefer to satisfy its goal rather than otherwise, no matter what the costs. The fundamental question that we study is whether the principal can impose a taxation scheme such that, in the resulting game, the principal's goal is satisfied in at least one or all runs of the game that could arise by agents choosing to follow game-theoretic equilibrium strategies. We consider two different types of taxation schemes: in a static scheme, the same tax is imposed on a state-action profile pair in all circumstances, while in a dynamic scheme, the principal can choose to vary taxes depending on the circumstances. We investigate the main game-theoretic properties of this model as well as the computational complexity of the relevant decision problems.Comment: In Proceedings TARK 2023, arXiv:2307.0400

An Empirical Study Into the Limitations and Emerging Trends of Six Sigma:Findings From a Global Survey

The purpose of this article is to identify and evaluate the limitations and emerging trends of Six Sigma from the perspectives of Six Sigma experts. The authors developed an online global survey and deployed the survey to 1250 Six Sigma experts of which 307 experts responded. The article finds integration of Six Sigma with Big Data to be the topmost among Asian, South American, and African experts, whereas European and North American experts felt Six Sigma in Small and Medium Sized Enterprises and Micro-enterprises would be very beneficial. The manufacturing sector experts nominated the topmost emerging trend as Six Sigma in Small and Medium Sized Enterprises and Micro-enterprises to be very challenging and will be rewarding if implemented properly. In the service sector, the topmost emerging trend was the integration of Six Sigma with Big Data. However, public sector experts felt variance reduction should not be the only goal of Six Sigma implementation. The that master black belts perceived Six Sigma in Small and Medium Sized Enterprises and Micro-enterprises would be advantageous, whereas Black and Green Belts perceived Integration of Six Sigma with Big Data to be topmost emerging trend