Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]- anion

The photo-, thermo- and solvatochromic properties of 2,3-dihydro-10,30,30-trimethyl-6-nitrospiro- [1-benzopyran-2,20-1H-indole] (BSP-NO2) were studied in ILs containing the anion [NTf2]- by UV-Vis absorption spectroscopy, ab initio molecular orbital theory and density functional theory (DFT) calculations. It was found that the kinetics and thermodynamics of the BSP-NO2 MC (merocyanine) equilibrium was sensitive to the nature of the cation. It was also observed that the imidazolium cation can form a through-space orbital interaction with the MC isomer, rather than a simple electrostatic interaction, thus preventing the MC conversion back to the BSP-NO2 isomer. The BSP-NO2 MC equilibrium thus serves as a model system for studying modes of interaction of the cations in ionic liquids

Synthesis and nanocharacterisation of magnetic nanoparticles: from cubes and spheres to octapods and wires

This thesis details the chemical synthesis and nanocharacterisation of magnetic nanoparticles (MNPs). Throughout this thesis, solution-based synthesis methods are used to fabricate MNPs with a variety of shapes, from spheres and cubes to wires and octapods. Chapter 3 assesses the role of polyol solvent in autoclave-based magnetite NP synthesis. It was found that solvents containing functional groups (especially primary alcohols) afforded the greatest control over final MNP morphology and that the presence of additional alkyl substituents could disrupt the packing of surfactant molecules around a particle surface, giving rise to more complex ‘compound’ MNPs. Magnetic measurements show the particles to be superparamagnetic, with saturation magnetisation values close to that of the bulk. In Chapter 4 It was found that by replacing the polyol solvents used in Chapter 3 with a large excess of bulky surfactant molecules it was possible to form high aspect ratio lanthanide oxide (LnOx) nanowires and ribbons. It was found that the nanowires formed via an intriguing 3-stage ‘oriented assembly’ mechanism, in which individual NPs form, before aligning anisotropically and recrystallising into a more crystallographically homogeneous product. The magnetic properties of Gd2O3 nanowires and Dy2O3 nanoribbons are very similar to those of discrete particles, implying that no long-range ordering exists in the nanowires. Optical characterisation of the Eu2O3 nanowires showed that there is an increase in fluorescence lifetime going from bulk Eu2O3 to the nanoscale. In Chapter 5 the high temperature reflux approach is used in the synthesis of manganese oxide (as MnO) particles, using manganese-containing polynuclear carboxylate complexes as precursors. It was found that control over MnO NP size and shape is dependent on many factors, such as the carboxylate ligand present in the precursor (which can disrupt particle stabilisation by surfactant molecules) and the heating regime, which ii determines if the particles grow under thermodynamic or kinetic growth regimes. The magnetic behaviour of MnO MNPs was found to be dependent on the relative number of surface spins present in the particles. In Chapter 6 new routes to gadolinium-doped magnetite particles are discussed. It was found that decomposition of a single-source precursor yielded doped magnetite particles which had a gadolinium content of 2–4%. Magnetic characterisation of these particles showed them to be superparamagnetic, with a reduced saturation magnetisation compared to bulk magnetite. Preliminary investigations showed that the gadolinium doped particles (after being rendered water soluble by a ligand exchange reaction) were readily taken up by human fibroblast cells and exhibited low toxicities

Race, Class, and the Distribution of Radioactive Waste in New England

Objective. Inequity in the distribution of environmental burdens among social groups, for example, minority and disadvantaged segments of the population, is an important topic in policy research. This research has largely focused on hazardous waste facilities and Superfund sites. Yet federal mandates to the states raise similar concerns over the social distribution of low-level radioactive waste facilities (LLRWFs). This study seeks to provide the first evaluation of equity in the distribution of LLRWFs within a state. Methods. We use data from the 1990 Census to compare selected characteristics of tracts with low-level radioactive waste facilities to tracts without, tracts nearby LLRWFs to those more distant, and tracts with LLRWFs, which may be more, and less, undesirable to other tracts. Results. Findings suggest that communities with LLRWFs differ from other tracts in their residents\u27 racial composition, socioeconomic status, industrial employment, and housing characteristics. LLRWFs more likely to be viewed as undesirable are even more likely to be located in areas with fewer white and affluent populations. Conclusions. Despite difficulties in assessing the relative risks and benefits of LLRWFs, our results support concern for environmental justice issues in the future siting of LLRWFs and in mandated state planning for low-level radioactive waste long-term storage

Selective Use of Pericardial Window and Drainage as Sole Treatment for Hemopericardium from Penetrating Chest Trauma

Background Penetrating cardiac injuries (PCIs) are highly lethal, and a sternotomy is considered mandatory for suspected PCI. Recent literature suggests pericardial window (PCW) may be sufficient for superficial cardiac injuries to drain hemopericardium and assess for continued bleeding and instability. This study objective is to review patients with PCI managed with sternotomy and PCW and compare outcomes. Methods All patients with penetrating chest trauma from 2000 to 2016 requiring PCW or sternotomy were reviewed. Data were collected for patients who had PCW for hemopericardium managed with only pericardial drain, or underwent sternotomy for cardiac injuries grade 1–3 according to the American Association for the Surgery of Trauma (AAST) Cardiac Organ Injury Scale (OIS). The PCW+drain group was compared with the Sternotomy group using Fisher’s exact and Wilcoxon rank-sum test with P\u3c0.05 considered statistically significant. Results Sternotomy was performed in 57 patients for suspected PCI, including 7 with AAST OIS grade 1–3 injuries (Sternotomy group). Four patients had pericardial injuries, three had partial thickness cardiac injuries, two of which were suture-repaired. Average blood drained was 285mL (100–500 mL). PCW was performed in 37 patients, and 21 had hemopericardium; 16 patients proceeded to sternotomy and 5 were treated with pericardial drainage (PCW+drain group). All PCW+drain patients had suction evacuation of hemopericardium, pericardial lavage, and verified bleeding cessation, followed by pericardial drain placement and admission to intensive care unit (ICU). Average blood drained was 240mL (40–600 mL), and pericardial drains were removed on postoperative day 3.6 (2–5). There was no significant difference in demographics, injury mechanism, Revised Trauma Score exploratory laparotomies, hospital or ICU length of stay, or ventilator days. No in-hospital mortality occurred in either group. Conclusions Hemodynamically stable patients with penetrating chest trauma and hemopericardium may be safely managed with PCW, lavage and drainage with documented cessation of bleeding, and postoperative ICU monitoring. Level of evidence Therapeutic study, level IV

Influence of dietary docosahexaenoic acid in combination with other long-chain polyunsaturated fatty acids on expression of biosynthesis genes and phospholipid fatty acid compositions in tissues of post-smolt Atlantic salmon (Salmo salar)

To investigate interactions of dietary LC-PUFA, a dose-response study with a range of docosahexaenoic acid (DHA; 22:6n - 3) levels (1 g kg- 1, 5 g kg- 1, 10 g kg- 1, 15 g kg- 1 and 20 g kg- 1) was performed with post-smolts (111 ± 2.6 g; mean ± S.D.) over a nine-week feeding period. Additional diets included 10 g kg- 1 DHA in combination with 10 g kg- 1 of either eicosapentaenoic acid (EPA; 20:5n - 3) or arachidonic acid (ARA; 20:4n - 6), and a diet containing 5 g kg- 1 each of DHA and EPA. The liver, brain, head kidney and gill were collected at the conclusion of the trial, and lipid and fatty acid compositions were determined as well as expression of genes of LC-PUFA biosynthesis. Total lipid content and class composition were largely unaffected by changes in dietary LC-PUFA. However, phospholipid (PL) fatty acid compositions generally reflected that of the diet, although the response varied between tissues. The liver most strongly reflected diet, followed by the head kidney. In both tissues increasing dietary DHA led to significantly increased DHA in PL and inclusion of EPA or ARA led to higher levels of these fatty acids. The brain showed the most conserved composition and gene expression profile, with increased dietary LC-PUFA resulting in only minor changes in PL fatty acids. Dietary LC-PUFA significantly affected the expression of Δ6 and Δ5 desaturases, Elovl 2, 4 and 5, and SREBPs although this varied between tissues with greatest effects observed in the liver followed by the head kidney, similar to PL fatty acid compositions

Thermophysiochemical properties of pure and water-saturated ionic liquids

We have previously reported into the extent of structuring in ILs using photochromic molecular probes1. In order for Ionic Liquids (ILs) to be fully utilized to their potential, it is necessary to have a complete understanding of their physical properties. In this study we investigated the thermophysical interactions in several pure and water-saturated ionic liquids being hydrophilic and hydrophobic in nature, namely 1-alkyl-3-methyl imidazolium and trihexyltetradecylphosphonium family of ILs. The density, viscosity and conductivity of pure and water-saturated imidazolium and phosphonium-based ILs were measured over a broad temperature. Moreover, interactive and binding energies of the studied imidazolium ILs in the presence of H2O molecules were calculated using Gaussian and compared with experimental Raman spectroscopy of the same imidazolium ILs, with and without the presence of saturated water

N-methyl-N-alkylpyrrolidinium nonafluoro-1-butanesulfonate salts : Ionic liquid properties and plastic crystal behaviour

A series of N-methyl-N-alkylpyrrolidinium nonafluoro-1-butanesulfonate salts were synthesised and characterised. The thermophysical characteristics of this family of salts have been investigated with respect to potential use as ionic liquids and solid electrolytes. N-Methyl-N-butylpyrrolidinium nonafluoro-1-butanesulfonate (p1,4NfO) has the lowest melting point of the family, at 94 &deg;C. Electrochemical analysis of p1,4 NfO in the liquid state shows an electrochemical window of ~6 V. All compounds exhibit one or more solid&ndash;solid transitions at sub-ambient temperatures, indicating the existence of plastic crystal phases.<br /

Temperature & pH triggered release characteristics of water/fluorescein from 1-ethyl-3-methylimidazolium ethylsulfate based ionogels.

A crosslinked Poly(N-isopropylacrylamide) ionogel encapsulating an ionic liquid exhibits improved transmittance properties, enhanced water uptake/release, greater thermal actuation behaviour and distinct solvatomorphology over its hydrogel equivalent. It was also found that the rate of release of fluorescein pre-loaded into membranes was considerably enhanced for ionogels compared to equivalent hydrogels, and could be triggered through changes in pH and temperature

A Push-Button Molecular Switch

The preparation, characterization, and switching mechanism of a unique single-station mechanically switchable hetero[2]catenane are reported. The facile synthesis utilizing a “threading-followed-by-clipping” protocol features Cu^(2+)-catalyzed Eglinton coupling as a mild and efficient route to the tetrathiafulvalene-based catenane in high yield. The resulting mechanically interlocked molecule operates as a perfect molecular switch, most readily described as a “push-button” switch, whereby two discrete and fully occupied translational states are toggled electrochemically at incredibly high rates. This mechanical switching was probed using a wide variety of experimental techniques as well as quantum-mechanical investigations. The fundamental distinctions between this single-station [2]catenane and other more traditional bi- and multistation molecular switches are significant

Donor-Acceptor Oligorotaxanes Made to Order

Five donor–acceptor oligorotaxanes made up of dumbbells composed of tetraethylene glycol chains, interspersed with three and five 1,5-dioxynaphthalene units, and terminated by 2,6-diisopropylphenoxy stoppers, have been prepared by the threading of discrete numbers of cyclobis(paraquat-p-phenylene) rings, followed by a kinetically controlled stoppering protocol that relies on click chemistry. The well-known copper(I)-catalyzed alkyne–azide cycloaddition between azide functions placed at the ends of the polyether chains and alkyne-bearing stopper precursors was employed during the final kinetically controlled template-directed synthesis of the five oligorotaxanes, which were characterized subsequently by ^1H NMR spectroscopy at low temperature (233 K) in deuterated acetonitrile. The secondary structures, as well as the conformations, of the five oligorotaxanes were unraveled by spectroscopic comparison with the dumbbell and ring components. By focusing attention on the changes in chemical shifts of some key probe protons, obtained from a wide range of low-temperature spectra, a picture emerges of a high degree of folding within the thread protons of the dumbbells of four of the five oligorotaxanes—the fifth oligorotaxane represents a control compound in effect— brought about by a combination of C-H···O and π–π stacking interactions between the p-electron-deficient bipyridinium units in the rings and the π-electron-rich 1,5-dioxynaphthalene units and polyether chains in the dumbbells. The secondary structures of a foldamer-like nature have received further support from a solid-state superstructure of a related [3]pseudorotaxane and density functional calculations performed thereon