2,428 research outputs found

    Synthesis, Properties, and Solid-State Structures of a Series of 6,13-Dicyanoheteropentacene Analogues: Towards New Liquid Crystalline Materials

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    The focus of this thesis is the synthesis of novel heterocyclic pentacene analogs and the investigation of their self-organization for the development of new materials for organic electronics. The thesis consists of two interrelated projects: the first being development of an improved synthesis of a series of liquid crystalline dicyanotetraoxapentacenes (DCTOPs) while the second entails the exploratory synthesis of several novel dicyanoheteropentacene analogues and a preliminary investigation of their photophysical properties and solid-state structures. Both of these projects centre around the use of nucleophilic aromatic substitution reactions on tetrafluoroterephthalonitrile. Soluble, tetrakis(bis(alkoxy)phenyl)-substituted DCTOPs were originally synthesised via a short synthesis complicated by a tedious purification required in the last step. Despite this, derivatives bearing long alkyl chains were prepared which displayed liquid crystalline properties in addition to aggregation-induced emission. Building upon this success, but with the goal of achieving DCTOPs in an efficient synthetic manner for this thesis, changes were made which eliminated the troublesome fourfold Suzuki coupling by changing the order of reactions, which in turn required a protection-deprotection sequence. Purification in the new synthesis was greatly simplified and the target tetraaryl-DCTOPs were accessed in good overall yields and purities. The synthesis and solid state structures of these DCTOPs are discussed in Chapter 2. Building on the methods developed in Chapter 2, several novel pentacene analogues containing combinations of nitrogen, oxygen, and sulfur atoms installed within the pentacene core were also synthesised. These compounds were prepared in good yields, and preliminary photophysical studies show that all the compounds displayed luminescence in solution and the solid state. It was also shown that replacement of O with N leads to a red shift in absorption and emission spectra. The X-ray crystal structures show that several of these compounds exhibit π−stacking in the solid state, which is an important design element for applications in organic electronics. The synthesis, photophysical properties, and solid-state organization of these novel 6,13-dicyanoheteropentacene analogues are discussed in Chapter 3

    Parenting in the early years and self-harm in adolescence: The role of control and reward systems in childhood

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    Background: Research suggests that early parenting may contribute to the development of self-harm but this has not been examined longitudinally. In this study, we explored the relationship between early parenting and selfharm in adolescence and considered whether (1) emotion regulation and (2) decision-making in childhood mediate the relationship between early parenting and self-harm. // Method: Using longitudinal data from the Millennium Cohort Study (MCS), we tested mediation models exploring the relationship between early parenting and self-harm in adolescence via emotion regulation and decisionmaking. Parenting was assessed at age 3 with measures of conflict, closeness and discipline. The trajectories of independence & self-regulation and emotional dysregulation were modelled from ages 3 to 7 years through latent growth curve analysis, with individual predicted slope and intercept values used in the mediation models. Decision-making (deliberation time, total time, delay aversion, quality of decision making, risk adjustment, risktaking) was assessed using the Cambridge Gambling Task (CGT) at age 11. // Results: In our sample (n = 11,145), we found no evidence of a direct association between early parenting and self-harm in adolescence. However, there were indirect effects of parenting (conflict and closeness) on self-harm via the slope of emotional dysregulation. Furthermore, delay aversion was positively associated with self-harm in adolescence. // Limitations: It must be acknowledged that we cannot determine causality and that self-report measures of parenting are vulnerable to several biases. // Conclusion: The findings support early identification and interventions for children exhibiting chronic emotional dysregulation and decision-making characterised by a bias for smaller, immediate over larger, delayed rewards

    Aquachlorido(2-{[6-(dimethylamino)pyrimidin-4- yl]sulfanyl}pyrimidine-4,6-diamine)copper(II) chloride hydrate

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    A copper(II) complex of the non-symmetric bidentate ligand 2-{[6-(di­methyl­amino)­pyrimidin-4-yl]sulfan­yl}pyrimidine-4,6-di­amine (L1) is reported. The single-crystal X-ray structure of aqua­[aqua/chlorido­(0.49/0.51)](2-{[6-(di­methyl­amino)­pyrimidin-4-yl]sulfan­yl}pyrimidine-4,6-di­amine)­copper(II) 0.49-chloride 1.51-hydrate, [CuCl1.51(C10H13N7S)(H2O)1.49]Cl0.49·1.51H2O or [(L1)Cl1.51(H2O)1.49Cu]0.49Cl·1.51H2O, exhibits distorted square-pyramidal geometry around the metal centre, with disorder in the axial position, occupied by chloride or water. The six-membered metal–chelate ring is in a boat conformation, and short inter­molecular S- - -S inter­actions are observed. In addition to its capacity for bidentate metal coordination, the ligand has the ability to engage in further supra­molecular inter­actions as both a hydrogen-bond donor and acceptor, and multiple inter­actions with lattice solvent water mol­ecules are present in the reported structure

    Noncommutative geometry, topology and the standard model vacuum

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    As a ramification of a motivational discussion for previous joint work, in which equations of motion for the finite spectral action of the Standard Model were derived, we provide a new analysis of the results of the calculations herein, switching from the perspective of Spectral triple to that of Fredholm module and thus from the analogy with Riemannian geometry to the pre-metrical structure of the Noncommutative geometry. Using a suggested Noncommutative version of Morse theory together with algebraic KK-theory to analyse the vacuum solutions, the first two summands of the algebra for the finite triple of the Standard Model arise up to Morita equivalence. We also demonstrate a new vacuum solution whose features are compatible with the physical mass matrix.Comment: 24 page

    Formation and emission of reactive chlorine in indoor air

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    Chlorine atoms are powerful atmospheric oxidants known to degrade air quality. Despite much focus, a direct measurement technique does not exist. Instead, chlorine atom precursors are used as proxies to study chlorine atom chemistry. Reactions of precursors resulting in chlorine atoms studied in outdoor environments are also possible indoors. Daily household activities, especially those involving chlorinated cleaning products, are suspected to contribute to indoor chlorine atom chemistry. Indoor air studies are hindered by sampling techniques, as few appropriate instruments exist. A common atmospheric measurement technique was evaluated while monitoring gas and particulate phase species emitted during indoor bleach use. This instrument collects a non-selective gaseous and a particulate chloride sample. Recent advances in indoor instrumentation allow for selective measurement of chlorine atom precursor, hydrogen chloride (HCl), using a cavity-ring down spectroscopy instrument. Present ubiquitously outdoors, atmospheric HCl is a result of direct emission and secondary production. Previous measurements of HCl indoors are rare and have been limited to non-residential buildings using integrated sampling. This sampling strategy does not provide the source of HCl emissions. In order to better understand sources of HCl indoors, real-time gas-phase mixing ratios of HCl during typical household activities were monitored such as floor exposure to bleach, detergent use in household dishwashers, and cooking events. Based on calculated rates of chlorine atom precursors, both photolysis and direct emission could be contributing to elevated HCl levels indoors. This work presents insights regarding HCl production and the influence of household activities on indoor air quality

    Проблема достоверности научного знания

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    Знание в самом общем виде можно определить как верное отражение в сознании человека явлений материального и духовного мира и, в частности, многообразных явлений общественной жизни

    Distribution and Size of Short-finned Squid (Illex illecebrosus) Larvae in the Northwest Atlantic from Winter Surveys in 1969, 1981 and 1982

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    During a plankton survey along the edge of the continental shelf south of New Jersey in February 1969. Illex sp. larvae were caught in the vicinity of the Florida Current between Cape Hatteras and central Florida (28°30'N 80° 00'W). The larva from the latter area represents the most southwesterly capture that has been reported to date. Illex sp. larvae were also caught during surveys in February-March of 1981 and 1982 south of Newfoundland in the northern partof the Gulf Stream, the most easterly capture being at 40°09'N 53°00'W and northerly capture at 41°00'N 56°00'W. The larvae taken off Florida were 1.1-6.2 mm mantle length (ML) and those from the region south of Newfoundland were 2.4-6.6 mm. From the observed distribution and sizes of larvae in relation to water masses associated with the Gulf Stream System and in the light of recent observations on Illex illecebrosus spawning in captivity and temperatures required for embryonic development, it is considered that spawning probably occurs pelagically a in the winter months within the Gulf Stream or in the Gulf Stream-Slope Water frontal zone south of Cape Hatteras
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