Photoactive Supramolecular Cyclodextrin Assemblies

Ligands with a macrocyclic host unit attached to a photoactive metal core are of interest across a range of applications from luminescent or electrochemical sensors, light harvesting and energy-collection purposes. Their versatile properties and possibility of associating cyclodextrins with other molecules both covalently and non-covalently mean that these macrocyclic ligands can be employed in the design and the formation of supramolecular complexes. A particularly attractive proposition is to combine the selective inclusion capabilities of CD with luminophores which may act as reporters of binding or other interactions at the cyclodextrin cavity. Ruthenium, osmium, and iridium polypyridyl complexes are particularly attractive reporters in this regard because of their visible emission and their useful redox properties. Their long lived excited states are particularly attractive providing significant scope for interaction with an included species compared with organic fluorphores, which can be very insensitive to their environments due to their fast radiative decays. In this thesis, we exploited the properties of CD and ruthenium polypyridyl complexes in designing photoactive metallocyclodextrin where 5-amino-1, 10-phenanthroline has been attached to the primary side of β-cyclodextrin. This ligand. β -CD-aphen has been used to design [Ru(bpy)2(aphen-CD). [Ru(bpy)2(aphen-CD) ][PF6]2 exhibits an intense luminescence ascribed to a 3MLCT state at room temperature in DMF and water with , λmax at 618 nm, a lifetime of approximately 1 μs and quantum yield of φ= 0.013 in deaerated solution. The secondary side of cyclodextrin is still available. We exploited the idea that metals like Copper and Zinc can be coordinated to the secondary side in constructing of molecular assembly where the donor and acceptor are held together via covalent link through a bridge. We have designed a trinuclear metallocyclodextrin-based donor-acceptor complex where the dicopper (II) sites are hydroxo bridged to the secondary side of β-CD in [Ru(bpy)2(aphen-CD)]. The donor and acceptor in our system are linked via a β-Cyclodextrin On the account of their relatively hydrophobic interiors; CDs have the ability to form inclusion complexes with wide range of Substrates. This idea has been exploited to bring the donor and the acceptor in a close proximity and study the energy and/or electron transfer in these novel supramoluclar assemblies. The effect of anthraquinone and anthraquinonecarboxcyclic on the luminescence of ruthenium was investigated in chapter three. In addition we demonstrate, for the first time, that the luminescence quantum yield and lifetime of Ru (II) polypyridyl center shows remarkable sensitivity to pH and we present detailed pH titrations for luminescence intensity and lifetime. The range of pH response is extremely broad, from pH 1 to pH 13 and alterations to luminescence quantum yield of greater than 60% are observed. In chapter 6 we have examined photoinduced transfer process between Ru and Ir metal centers in water mediated by non-covalent interactions through a cyclodextrin cavity. On the basis of the inclusion ability of β-CD and the redox properties of pyrene we have studied Ru-Ir interaction in trimer [Ir-(RuCD)2] in aqueous solution. Formation of the Ru-Py-Ir trimer through cyclodextrins induces significant changes in the photophysical behavior of both pyrene and appended Ruthenium. We couldn’t detect a significant change in the photophysical of Iridium metal centre. This means that communication between the two metal centers is very weak. This behavior may be attributed to the presence of pyrene moiety which blocks the interaction between the two metal centers. In [Ir-(RuCD)2] pyrene acts as a store for the energy instead of mediating the transfer process. Future work on these complexes will include further studies on the nature of the electron transfer process. This will include, for example, more detailed transient absorption spectroscopy to discern the direction of transfer either Ir→ Ru or Py→Ru or both. We then extended our work to make homonuclear photoactive cyclodextrins dimers. These dimers comprised of two photoactive metal centers covalently attached to the primary side of γ-cyclodextrin. In chapter 5, we exploit the inclusion ability to design a tetrameric metallocyclodextrins containing photoactive Ru(II) polypyridyl units covalently bonded to γ-CD. Then the cyclodextrin complexes were self-assembled with a fullerene moiety in 2:1 ratio to produce the tetramer. The synthesis and characterization of the complexes and in particular their spectroscopic electrochemical and photophysical properties described. We provide evidence for photoinduced processes and discuss the possibility of electron and energy transfers in these novel supramolecular assemblies

Regulation Not Prohibition: The Comparative Case Against the Insurable Interest Doctrine

American law requires an insurable interest—a pecuniary or affective stake in the subject of an insurance policy—as a predicate to properly obtaining insurance. In theory, the rule prevents both wagering on individual lives and moral hazard. In practice, the doctrine is avoided by complex insurance transaction structuring to effectuate both origination and transfers of insurance by individuals without an insurable interest. This paper argues that it is time to abandon the insurable interest doctrine. As both the English and Australian experiences indicate, elimination of the insurable interest doctrine will have little detrimental pecuniary effect on the insurance industry, while freeing consumers considerably. Indeed, New York comes to the brink of eliminating the doctrine in its recent decision in Kramer v. Phoenix Life Insurance Co. by sanctioning an immediate life insurance assignment procedure that in effect eliminates the need for an insurable interest in the assignee. However, Delaware, in PHL Variable Insurance Co. v. Price Dawe 2006 Insurance Trust and Lincoln National Life Insurance Co. v. Joseph Schlanger 2006 Insurance Trust, breathes new life into an old doctrine. Overall, though, adhering to an arcane doctrine that prevents the value of an insurance policy from being realized without extreme legal burden both hampers the market and harms consumers, as the benefits of such transactions are both lessened by transaction costs and accrue to only a select few individuals

Regulation Not Prohibition: The Comparative Case Against the Insurable Interest Doctrine

American law requires an insurable interest—a pecuniary or affective stake in the subject of an insurance policy—as a predicate to properly obtaining insurance. In theory, the rule prevents both wagering on individual lives and moral hazard. In practice, the doctrine is avoided by complex insurance transaction structuring to effectuate both origination and transfers of insurance by individuals without an insurable interest. This paper argues that it is time to abandon the insurable interest doctrine. As both the English and Australian experiences indicate, elimination of the insurable interest doctrine will have little detrimental pecuniary effect on the insurance industry, while freeing consumers considerably. Indeed, New York comes to the brink of eliminating the doctrine in its recent decision in Kramer v. Phoenix Life Insurance Co. by sanctioning an immediate life insurance assignment procedure that in effect eliminates the need for an insurable interest in the assignee. However, Delaware, in PHL Variable Insurance Co. v. Price Dawe 2006 Insurance Trust and Lincoln National Life Insurance Co. v. Joseph Schlanger 2006 Insurance Trust, breathes new life into an old doctrine. Overall, though, adhering to an arcane doctrine that prevents the value of an insurance policy from being realized without extreme legal burden both hampers the market and harms consumers, as the benefits of such transactions are both lessened by transaction costs and accrue to only a select few individuals

Financial market efficiency : a study of the time series properties of the Jordanian stock market

The ASE has developed greatly since its establishment and has succeeded in accomplishing several of its goals by mobilising capital into the productive sectors of the economy. ASE appears to be well organised, attractive, and aims to attract international investments in order to increase the depth of the market. The aim of the study is to explore the efficiency of this emerging market and investigate the integration with other capital markets in the region. Conventional tests beside recent econometric techniques are implemented. The thesis starts with a review of the development of the efficient market hypothesis, followed by an overview of the development of the Jordanian Financial Market. The autocorrelation and runs test - runs up and down, distributions of runs by length, and runs above and below -are applied to the daily price indices of ASE to examine whether ASE is weak form efficient. The empirical results reflect significant positive dependency patterns in stock prices and suggest that the price behaviour in ASE does not follow the random walk model over time. However, further investigation is applied to find whether these results could be exploited, through technical analysis, to outperform the simple buy and hold policy. Filter rules and moving average techniques are used. Furthermore, and for the results of moving average techniques, standard statistical testing is extended through the use of bootstrap techniques. According to the moving average rule, buy and sell signals are generated by two moving averages of the level of the index (long and short period averages). The conditional returns on buy or sell signals from actual data are compared to the conditional returns from simulated series generated by a range of models (random walk with a drift, AR (1), and GARCH-(M)). The results of this part of the study generally suggest that technical analysis helps predict stock price changes in the Jordanian stock market. In the next part of the thesis, recent econometric Procedures are employed to investigate the behavioural properties of ASE indices. The Box-Jenkins estimation, irrespective of the index examined produced different models with a high prediction performance, violating the EM: H conditions. The unit-root test also confirmed these results as the return series for all indices did not exhibit unit root, and all processes were stationary. The GARCH-M(l, l) model is estimated and present mix results cross the indices. To a certain limit, the results support the existence of a significant link between conditional volatility and stock returns, and the conditional variance is found to change over time as a result of volatility clustering effects. The last part of the thesis applies the cointegration and Granger causality tests to investigate the concept of market integration and comovements. These techniques are applied using, firstly, the five Jordanian daily indices, and secondly, the weekly price indices for ten MENA (Middle East and North Africa) markets. The cointegration test between the Jordan index and every other market index is applied. Moreover, different groups of markets (GCC, Africa, and Europe) are composed and the cointegration test is applied for each group. Results suggest that the Jordanian stock market does not exhibit a long run relationship with most other markets, and there is an advantage for investors looking for diversification in the Middle East markets.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

High density lipoprotein metabolism in health and disease

High density lipoprotein increasingly attracts the attention of investigators working in the atherosclerosis field due to the reported negative correlation found between its plasma levels and the incidence of ischaemic heart disease. However, the present classification of HDL depends on the flotation properties of its subfractions, but such fractions may not represent distinct biological entities. This project sets out to sub-fractionate HDL according to its apoprotein content rather than its flotation density, and to investigate the metabolism of these subfractions under a variety of conditions. Moreover, the effects of two hypol ipidaemic drugs on HDL metabolism are studied in a group of hypertriglyceridaemic patients. HDL is prepared from normolipidaemic females and subfractionated by means of immunoaffinity chromatography. The physical and chemical properties of the isolated subfractions are studied and three methods for their quantitation presented. The distribution of these subfractions in plasma and in HDL density subclasses is studied in the normal state, during nicotinic acid and probucol therapy. Mathematical analysis of the tracer decay data is also discussed. The results of these studies are summarised as follows: 1. HDL can be subfractionated into two meta-bolically distinct types of particles, i.e., those containing primarily apo-AI without apo-AII and those with both apoproteins. Both species are detectable and have been quantified in fresh plasma and in HDL density subclasses. It is found that HDL2 from normal young females contain a higher proportion of the (AI)HDL particles (71%) than HDL3 (43%). Moreover, it is demonstrated that minimal exchange of A apoproteins seems to occur between the two types of particles. 2. The kinetic behaviour of (AI)HDL is, generally, similar to that of total HDL. On the other hand, their apoproteins show inconsistent deviations in the locations of their catabolism. Evidence for intravascular and extravascular site of catabolism is discussed. 3. Nicotinic acid is shown to have a reciprocal effect on (AI)HDL and (AI/AII)HDL. It raised the plasma levels of the former by 20% (p<0.05) and lowered those of the latter by 19.5% (p<0.05). A similar effect was observed on HDL2 and HDL3 concentrations. The former rose by 45% (p<0.01) and the latter fell by 28% (p<0.01) during treatment with the drug. The rise in the former was attributable in its entirety to an increase of its (AI)HDL content (20%, p<0.01). 4. Probucol, unlike nicotinic acid, lowers the plasma concentration of (AI)HDL by 22% (p<0.01) and of HDL2 by 58% (p<0.05) but it has no consistent effect on either (AI/AII)HDL or HDL3. The drop in HDL3 level is mainly a result of a reduction in its (AI)HDL content. In hypertriglyceridaemia the drug reduced the plasma levels of apo-AI , apo-AII and HDL. The decrease in the latter is due mainly to a fall in the HDL3 level. This was associated with a reduction in the plasma level of apo-AII due to a fall in its rate of synthesis. Moreover, the treatment with the drug affected the composition of HDL where its cholesterol content was decreased with a concomitant increase in the protein content. 5. Bezafibrate shows little influence on HDL metabolism. 6. Examination of three mathematical approaches for tracer data analysis, i.e., curve peeling (Matthews), multicompartmental (Berman) and graphical integration (Nosslin) methods, showed that the same value of the total fractional catabolic rate of HDL can be obtained by any of these procedures. In addition, calculation of the extravascular catabolic rate can be done by the last two methods which produced similar results

Dividend Signalling Hypothesis In Emerging Markets: More Empirical Evidence

The main objective of this study is to examine empirically the signalling theory for a sample of firms listed at Amman Stock Exchange (ASE) during the period 2005 to 2010. The sample consists of 183 observations and 132 observations for dividend release sample and no-dividend release sample, respectively. Event Study Methodology (ESM) is applied to examine the market reaction to dividend release announcements. The market model is used to generate the expected returns. Also, the t-test is used to examine the significance of the mean and cumulative abnormal returns. Results from the dividend release sample shows that there is a significant positive abnormal return on the announcement days. Also, it shows that there is an overreaction straight after the announcement day, then a correcting attempt in the post event and then it goes back to normal, which is consistent with the signalling hypothesis. For the no-dividend release sample, the results show no significant abnormal return on and around the announcement days which is again consistent with the signalling hypothesis. Our results are consistent with Al-Shattarat et al. (2012) suggestions that there could be value relevance for dividends rather than dividends’ change. Our findings show that there is value relevance for dividends and thus supporting the signalling hypothesis

Apolipoprotein A-II Influences Apolipoprotein E-Linked Cardiovascular Disease Risk in Women with High Levels of HDL Cholesterol and C-Reactive Protein

Background: In a previous report by our group, high levels of apolipoprotein E (apoE) were demonstrated to be associated with risk of incident cardiovascular disease in women with high levels of C-reactive protein (CRP) in the setting of both low (designated as HR1 subjects) and high (designated as HR2 subjects) levels of high-density lipoprotein cholesterol (HDL-C). To assess whether apolipoprotein A-II (apoA-II) plays a role in apoE-associated risk in the two female groups. Methodology/Principal: Outcome event mapping, a graphical data exploratory tool; Cox proportional hazards multivariable regression; and curve-fitting modeling were used to examine apoA-II influence on apoE-associated risk focusing on HDL particles with apolipoprotein A-I (apoA-I) without apoA-II (LpA-I) and HDL particles with both apoA-I and apoA-II (LpA-I:A-II). Results of outcome mappings as a function of apoE levels and the ratio of apoA-II to apoA-I revealed within each of the two populations, a high-risk subgroup characterized in each situation by high levels of apoE and additionally: in HR1, by a low value of the apoA-II/apoA-I ratio; and in HR2, by a moderate value of the apoA-II/apoA-I ratio. Furthermore, derived estimates of LpA-I and LpA-I:A-II levels revealed for high-risk versus remaining subjects: in HR1, higher levels of LpA-I and lower levels of LpA-I:A-II; and in HR2 the reverse, lower levels of LpA-I and higher levels of LpA-I:A-II. Results of multivariable risk modeling as a function of LpA-I and LpA-I:A-II (dichotomized as highest quartile versus combined three lower quartiles) revealed association of risk only for high levels of LpA-I:A-II in the HR2 subgroup (hazard ratio 5.31, 95% CI 1.12-25.17, p = 0.036). Furthermore, high LpA-I: A-II levels interacted with high apoE levels in establishing subgroup risk. Conclusions/Significance: We conclude that apoA-II plays a significant role in apoE-associated risk of incident CVD in women with high levels of HDL-C and CRP

Efficacy and micro-characterization of pathophysiological events on caries-affected dentin treated with glass-ionomer cements

The aim of this study was to evaluate if mechanical cycling influences bioactivity and bond strength at the glass-ionomer cement-dentin interface, after load cycling. Microtensile bond strength (MTBS) was assessed with Ketac-Bond (conventional glass ionomer/GIC) or Vitrebond Plus (resin-modified/RMGIC), in sound dentin or in cariesaffected dentin (CAD). Debonded dentin surfaces were studied by field emission scanning electron microscopy (FESEM), and remineralization was evaluated through nanohardness (Hi) and Young’s modulus (Ei), Raman spectroscopy, and Masson's trichrome staining technique. Load cycling did not affect MTBS, except when Ketac- Bond was applied on sound dentin, which attained 100% pretesting failures. Minerals precipitated in porous platforms. GIC promoted total occlusion of tubules, and RMGIC originated empty or partial occluded tubules. In sound dentin, load cycling produced an increase of the relative presence of crystalline minerals after using Ketac-Bond (Phosphate peak, from 18.04 up to 81.29 cm-1 at hybrid layer, and from 19.28 up to 108.48 cm-1 at the bottom of the hybrid layer; Carbonate peak, from 8.06 up to 15.43 cm-1 at the hybrid layer, and from 7.22 up to 19.07 cm-1 at the bottom of the hybrid layer). Vitrebond Plus, in sound dentin, attained opposite outcomes. In CAD treated with Ketac- Bond, the highest Hi (1.11 GPa) and Ei (32.91 GPa) values were obtained at the hybrid layer after load cycling. This GIC showed increased and immature mineral components (an average of 25.82 up to 30.55 cm-1), higher frequencies of crosslinking (considering the pyridinium ring at hybrid layer, from 4.1 up to 6.86 cm-1; at bottom of the hybrid layer, from 7.55 up to 8.58 cm-1) and worst collagen quality (considering the ratio amide I/AGEs-pentosidine at the hybrid layer, from 0.89 up to 0.69 cm-1; at the bottom of the hybrid layer, from 1.39 up to 1.29 cm-1) after load cycling, at the interface of the CAD samples. Both Hi and Ei of CAD treated with RMGIC were not affected 4 after load cycling, though phosphates, carbonates and crystallinity increased. The organic components showed a dissimilar crosslinking and an improvement of the nature of collagen. Trichrome staining showed lower signs of demineralization or exposed proteins after mechanical loading, though Vitrebond Plus exhibited a slight increment in red intensity at the interface. The null hypothesis to be tested is that bond strength, chemical bonding and mechanical performance of the tested ionomer-based cements would not be influenced by the application of load cycling on restorations of sound and caries-affected dentin substrates.Project MAT2014-52036-P supported by the Ministery of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER)