Synthesis and characterisation of phosphorescent rhenium(I) complexes of hydroxy- and methoxy-substituted imidazo[4,5- f ]-1,10-phenanthroline ligands

Eight new fluorescent ligands (L1-L8) derived from the fused imidazo[4,5-f]-1,10-phenanthroline core, have been synthesised utilising a one-pot methodology. The ligands include two points of structural variety, allowing multiply-substituted aryl groups (including hydroxy and methoxy moieties) to be attached to the ligand core. The ligands L1-L8 are fluorescent (λem = 399–426 nm) and react with pentacarbonylbromorhenium to give coordination complexes of the form fac-[ReBr(CO)3(NˆN)] (where NˆN = L1-L8). The complexes were characterised using a variety of spectroscopic and analytical techniques, including single crystal X-ray diffraction studies on two examples. The rhenium complexes were all found to be luminescent, revealing classical 3MLCT emission at 579–587 nm in aerated solution with corresponding lifetimes in the range 149–166 ns

Measurement of radiative proton capture on F 18 and implications for oxygen-neon novae reexamined

Background: The rate of the F18(p,γ)Ne19 reaction affects the final abundance of the radioisotope F18 ejected from novae. This nucleus is important as its abundance is thought to significantly influence the first-stage 511-keV and continuum γ-ray emission in the aftermath of novae. No successful measurement of this reaction existed prior to this work, and the rate used in stellar models had been calculated based on incomplete information from contributing resonances. Purpose: Of the two resonances thought to provide a significant contribution to the astrophysical reaction rate, located at Ec.m.=330 and 665 keV, the former has a radiative width estimated from the assumed analog state in the mirror nucleus, F19, while the latter resonance does not have an analog state assignment, resulting in an arbitrary radiative width being assumed. As such, a direct measurement was needed to establish what role this resonance plays in the destruction of F18 at nova temperatures. This paper extends and takes the place of a previous Letter which reported the strength of the Ec.m.=665 keV resonance. Method: The DRAGON recoil separator was used to directly measure the strength of the important 665-keV resonance in this reaction, in inverse kinematics, by observing Ne19 reaction products. A radioactive F18 beam was provided by the ISAC facility at TRIUMF. R-matrix calculations were subsequently used to evaluate the significance of the results at astrophysical energies. Results: We report the direct measurement of the F18(p,γ)Ne19 reaction with the reevaluation of several detector efficiencies and the use of an updated Ne19 level scheme in the reaction rate analysis. The strength of the 665-keV resonance (Ex=7.076 MeV) is found to be an order of magnitude weaker than currently assumed in nova models. An improved analysis of the previously reported data is presented here, resulting in a slightly different value for the resonance strength. These small changes, however, do not alter the primary conclusions. Conclusions: Reaction rate calculations definitively show that the 665-keV resonance plays no significant role in the destruction of F18 at nova temperatures

The ethics of uncertainty for data subjects

Modern health data practices come with many practical uncertainties. In this paper, I argue that data subjects’ trust in the institutions and organizations that control their data, and their ability to know their own moral obligations in relation to their data, are undermined by significant uncertainties regarding the what, how, and who of mass data collection and analysis. I conclude by considering how proposals for managing situations of high uncertainty might be applied to this problem. These emphasize increasing organizational flexibility, knowledge, and capacity, and reducing hazard

Synthetic routes, characterization and photophysical properties of luminescent, surface functionalized nanodiamonds

The functionalization of small diameter (ca. 50 nm) polycarboxylated nanodiamond particles using amide coupling methodologies in both water and acetonitrile solvent has been investigated. In this manner, the surfaces of nanodiamond particles were adorned with different luminescent moieties, including a green fluorescent 1,8-naphthalimide species (Nap-1), and a red emitting ruthenium(II) tris-bipyridine complex (Ru-1), as well as dual functionalization with both luminophores. Comprehensive characterization of the surface functionalized nanodiamonds has been achieved using a combination of dynamic light scattering, nanoparticle tracking analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, zeta potential measurements, microwave plasma atomic emission spectroscopy and time-resolved photophysics. The tendency of the functionalized nanodiamonds to aggregate reflects the degree of surface substitution, yielding small aggregates with typical particle sizes ca. 150 nm. This is likely to be driven by the reduction of the zeta potential, concomitant with the conversion of surface charged carboxylate groups to neutral amide functions. The results show that luminescent nanodiamond materials can be synthesised with tuneable photophysical properties

The abundance of 44Ti in core collapse supernovae : Measuring the 44Ti(α, p)47V reaction

Publisher PD

Aryl, bi-functionalised imidazo[4,5-f]-1,10-phenanthroline ligands and their luminescent rhenium(I) complexes

Five new imidazo[4,5-f]-1,10-phenanthroline based ligands (1–5) have been synthesised and characterised. The facile synthesis of 1–5 allows two regiochemical points of structural variety allowing highly conjugated and bulky aryl groups of varying functionalities, including azobenzene, trityl and terpyridine constituents, to be attached to the ligand core. 1–5 are fluorescent (λem = 410–415 nm), and react readily with [ReBr(CO)5] in toluene to give neutral coordination complexes of the form fac-[ReBr(CO)3(1–5)]. The series of complexes was characterised using a variety of spectroscopic and analytical techniques. Two examples of this series were characterised in the solid state using single crystal X-ray diffraction which confirmed the octahedral geometry and formulation. Photophysical studies showed that fac-[ReBr(CO)3(1–5)] are phosphorescent in solution under ambient conditions, revealing visible emission (558–585 nm) in aerated solution with corresponding lifetimes in the range 149–267 ns. These attributes are consistent with a triplet metal to ligand charge transfer (3MLCT) emitting state

Examining the quality and management of non-geometric building information modelling data at project hand-over

Through the exponential global increase of Building Information Modelling (BIM) adoption across the Construction industry, and the emergence of inter-connected, strategic and data-rich solutions; such as Big Data, the Internet of Things and Smart Cities, the importance associated with activities and decisions reliant on exact data input, transaction, analysis, and resulting actions becomes exponentially magnified. The supply of inaccurate BIM data may negatively impact on systems and processes that require fully assured data of appropriate quality/veracity, to support informed decision making, deliver functionality, facilitate services, or direct strategic actions within the built environment. This preliminary research intends to provide a catalyst for discussion, analysis and information retrieval relating to Building Information Modelling (BIM) processes where non-geometric data errors may; or are predicted to occur within a project environment. This may result in the delivery of data that cannot be described as representing truth or of good quality, and therefore of little value or use to the data user. The wider aspects of this research investigates specifically non-geometric data veracity & associated dimensions of data quality; in order to discover and explore future solutions to resolve current industry data quality assessment challenges. This paper provides feedback from the research focusing on the current state, presenting existing industry challenges and proposes further research areas based on initial findings

Study of the Ti-44(alpha, p)V-47 reaction and implications for core collapse supernovae

Peer reviewe

Direct measurement of resonance strengths in S 34 (α,γ) Ar 38 at astrophysically relevant energies using the DRAGON recoil separator

Background: Nucleosynthesis of mid-mass elements is thought to occur under hot and explosive astrophysical conditions. Radiative α capture on S34 has been shown to impact nucleosynthesis in several such conditions, including core and shell oxygen burning, explosive oxygen burning, and type Ia supernovae. Purpose: Broad uncertainties exist in the literature for the strengths of three resonances within the astrophysically relevant energy range (ECM=1.94-3.42MeV at T=2.2GK). Further, there are several states in Ar38 within this energy range which have not been previously measured. This work aimed to remeasure the resonance strengths of states for which broad uncertainty existed as well as to measure the resonance strengths and energies of previously unmeasured states. Methods: Resonance strengths and energies of eight narrow resonances (five of which had not been previously studied) were measured in inverse kinematics with the DRAGON facility at TRIUMF by impinging an isotopically pure beam of S34 ions on a windowless He4 gas target. Prompt γ emissions of de-exciting Ar38 recoils were detected in an array of bismuth germanate scintillators in coincidence with recoil nuclei, which were separated from unreacted beam ions by an electromagnetic mass separator and detected by a time-of-flight system and a multianode ionization chamber. Results: The present measurements agree with previous results. Broad uncertainty in the resonance strength of the ECM=2709keV resonance persists. Resonance strengths and energies were determined for five low-energy resonances which had not been studied previously, and their strengths were determined to be significantly weaker than those of previously measured resonances. Conclusions: The five previously unmeasured resonances were found not to contribute significantly to the total thermonuclear reaction rate. A median total thermonuclear reaction rate calculated using data from the present work along with existing literature values using the STARLIB rate calculator agrees with the NON-SMOKER statistical model calculation as well as the REACLIB and STARLIB library rates at explosive and nonexplosive oxygen-burning temperatures (T=3-4GK and T=1.5-2.7GK, respectively)