Design of superatomic systems: exploiting favourable conditions for the delocalisation of d-electron density in transition metal doped clusters.

The incorporation of transition metals into superatomic species has led to the proposal of highly tailorable systems, with the transition metal atoms typically acting as magnetic dopants. However, the extent to which d-electrons are able to delocalise from their ionic cores has not been fully recognised. In this work a variety of systems have been explored using a range of exchange-correlation functionals commonly used to explore cluster species, to test the extent of d-electron delocalisation under favourable conditions. Early transition metals have been shown to readily delocalise their valence d-electrons for superatomic shell closing, with higher period atoms showing a greater tendency for delocalisation. Our findings also provide the framework for the design of superatomic systems with large numbers of electrons being contributed from a single atom.

5-Fold symmetry in superatomic scandium clusters: exploiting favourable orbital overlap to sequester spin.

The geometries and electronic structures of icosahedral A13C (A = Sc, Y; C = 0, ±1, ±2) clusters have been determined at a range of multiplicities at each cluster charge, using density functional theory methods. These clusters demonstrate a complex electronic structure which provides insight into the anomalously high magnetic moment of icosahedral group 3 clusters and further contextualises the role of transition metals and d-electrons within the superatomic model. Embedded deeply within the density of states for these clusters are typical superatom orbitals which are populated up to the 2S level. Above the 2S-state there are three states of apparent F symmetry, which are preferentially singly occupied, followed by an abundance of approximately degenerate P-, G-, D- and F-states at the Fermi energy, which are at most singly occupied. In spite of apparent angular symmetry and a nodal structure reminiscent of superatomic orbitals these states are actually formed from preferential overlap of the valence d-orbitals of the cluster atoms. This analysis was further contextualised through analysis of the Sc19 cluster, which shows a similar construction of Kohn-Sham states, but with the breaking of 5-fold symmetry along one of its Cartesian axes. Finally, this work clearly demonstrates the ability of d-electrons to give rise to superatomic orbitals is not just constrained by atomic species but also by the local environment of the atoms.

On the influence of exact exchange on transition metal superatoms.

The electronic structure of A7C (A = Hg, Pd, V, Cr, Mn, Fe, Ni, Cu; C = 0, ±1, ±2) clusters has been determined using density functional theory methods. The A7C (A = Hg, Pd, Cr, Cu; C = 0, ±1, ±2) clusters all conform to the existing superatomic model, with a sufficiently stabilised local structure to prevent perturbation upon the introduction of exact exchange to the exchange correlation functional. For the A7C (A = Mn, Fe, Ni; C = 0, ±1, ±2) clusters the incorporation of exact exchange separates the atomic s- and d-electrons, leading to a net increase in the number of superatomic electrons. Conversely the incorporation of exact exchange into the exchange correlation functional decreases the number of superatomic electrons for the V7C (C = 0, ±1, ±2) clusters, owing to the radial extension of the d-orbitals influencing their ability to contribute into superatomic shells.

On the involvement of d-electrons in superatomic shells: the group 3 and 4 transition metals.

The geometries and electronic structures of small M7C (M = Sc, Y, La, Ti, Zr, Hf; C = 0, ±1, ±2) clusters have been calculated at a range of multiplicities at each cluster charge, using density functional theory methods. These clusters conform to the existing superatom model, with some contextual differences. There are a range of states which are populated by the outermost s and d-electrons of the constituent atoms, with an irregular Aufbau rule for the states formed from the atomic d-electrons. The states comprised of d-electrons present themselves as two states of P-symmetry and two states of F-symmetry, which are nearly degenerate, followed by states of D-symmetry, a shell ordering which arises due to the symmetry, and favourable overlap, of the contributing states. The effect of exact exchange in modulating the localisation of these states is also discussed. In addition, this study shows pseudo-superatomic states which arise due to the 5-fold symmetry of the clusters, materialising as either a ring or plane of electron density. In summary, these observations allow for an expansion of the role that early transition metals have within the existing superatom framework.

Superatomic states in nickel clusters: Revising the prospects for transition metal based superatoms.

The geometries and electronic structures of small Ninz clusters (n = 8, 9, 10) (z = 0, ±1, 2) have been elucidated for a range of multiplicities for each cluster size and charge, using density functional theory methods. These clusters have been found to conform in part to the existing superatomic model, with each cluster having a filled superatomic S-orbital, filled or partially filled superatomic P-orbitals, and empty or partially filled superatomic D-orbitals. Despite local states of mixed symmetry being present in the immediate vicinity of the Fermi energy, the addition or removal of a single electron from these systems causes a significant shift in the relative energies of the superatomic orbitals. In addition, this study demonstrates the possibility for d-electrons to contribute into superatomic orbitals to a greater or lesser extent, depending on the local environment. In summary, these observations lead to the prospect of a predictive model for electronic shell closings in some transition metal cluster systems.

Resilience to periodic disturbances and the long-term genetic stability in Acropora coral.

Climate change is restructuring natural ecosystems. The direct impacts of these events on biodiversity and community structure are widely documented, but the impacts on the genetic variation of populations remains largely unknown. We monitored populations of Acropora coral on a remote coral reef system in northwest Australia for two decades and through multiple cycles of impact and recovery. We combined these demographic data with a temporal genetic dataset of a common broadcast spawning corymbose Acropora to explore the spatial and temporal patterns of connectivity underlying recovery. Our data show that broad-scale dispersal and post-recruitment survival drive recovery from recurrent disturbances, including mass bleaching and mortality. Consequently, genetic diversity and associated patterns of connectivity are maintained through time in the broader metapopulation. The results highlight an inherent resilience in these globally threatened species of coral and showcase their ability to cope with multiple disturbances, given enough time to recover is permitted.

Development of a sensitive, quantitative assay with broad subtype specificity for detection of total HIV-1 nucleic acids in plasma and PBMC.

An LTR-based quantitative PCR (qPCR) assay was modified and optimized for the quantification of total HIV-1 nucleic acids in plasma and PBMC. TaqMan qPCR primers and probes were designed against the NCBI/LANL HIV-1 compendium database by analyzing sequences used in assays for sensitive cross-clade detection of HIV-1 as reported in the literature and elucidating regions of improved cross-subtype specificity. Inosine and mixed nucleotide bases were included at polymorphic sites. Real-time RT-qPCR and qPCR were performed on plasma viral RNA and cellular lysates. A step-up amplification approach to allow binding of primers across polymorphic regions showed improved sensitivity compared to universal cycling. Unlike a lead competing laboratory-developed assay, all major HIV-1 subtypes, and a wide range of recombinants from a 127-member diversity panel were detected and accurately quantified in spiked plasmas. Semi-nested PCR increased detection sensitivity even further. The assay was able to detect down to 88 copies/mL of HIV-1 in plasma with 95% efficiency or the equivalent of a single infected cell. The PCR assay will be valuable in studies that monitor very low viral levels including residual or break through HIV-1 in patients receiving antiretroviral therapy, in HIV-1 cure, and in other research studies.

Efficacy of intraperitoneal local anaesthetic techniques during laparoscopic cholecystectomy.

BACKGROUND: Pain following laparoscopic cholecystectomy (LC) is a barrier to early discharge. Some studies have demonstrated that local anaesthetic (LA) washed over the liver and gallbladder decreases postoperative pain. In many patients pain is partially of diaphragmatic origin which may not be treated effectively by topical wash. This study assesses the efficacy of LA injected to the peritoneum of the right hemidiaphragm or topical wash with a control group. METHODS: We performed a double-blind randomized sham controlled trial of 128 consecutive subjects who underwent elective LC. Patients received subcutaneous bupivacaine, a diaphragmatic injection of bupivacaine or sham, and topical wash over the liver/gallbladder with bupivacaine or sham depending upon allocation. The primary outcome was VAS pain scores on the ward. Secondary outcomes included VRS pain scores in theatre recovery, analgesic use, physiological observations, time to eating and ambulation, and successful day-case surgery. RESULTS: Pain scores were significantly lower in both LA groups versus control in theatre recovery but only in the subperitoneal diaphragm injection group when the patients returned to the ward. Subperitoneal diaphragm injection was associated with a reduced time in theatre recovery (p = 0.04). CONCLUSIONS: Intraperitoneal techniques of LA during LC decrease postoperative pain and shorten time in theatre recovery. Injection of LA to the right hemidiaphragm is associated with lower pain scores for a longer period following LC than a previously validated wash technique.

Size-dependent trends in the hydrogen evolution activity and electronic structure of MoS2 nanotubes.

The thermodynamics of hydrogen evolution on MoS2 nanotubes is studied for the first time using periodic density functional theory calculations to obtain hydrogen adsorption free energies (ΔG Hads ) on pristine nanotubes and those with S-vacancy defects. Armchair and zigzag MoS2 nanotubes of different diameters, ranging from 12 to 22 Å, are examined. The H adsorption energy is observed to become more favourable (lower ΔG Hads ) as nanotube diameter decreases, with ΔG Hads values ranging from 1.82 to 1.39 eV on the pristine nanotubes, and from 0.03 to -0.30 eV at the nanotube S-vacancy defect sites. An ideal thermoneutral ΔG Hads value of nearly 0 eV is observed at the S-vacancy site on nanotubes around 20 to 22 Å in diameter. For the pristine nanotubes, density of states calculations reveal that electron transfer from S to Mo occurs during H adsorption, and the energy gap between these two states yields a highly reliable linear correlation with ΔG Hads , where a smaller gap leads to a more favourable hydrogen adsorption. For the S-vacancy defect site the H adsorption resembles that on a pure metallic surface, meaning that a traditional d-band centre model can be applied to explain the trends in ΔG Hads . A linear relation between the position of the Mo d-states and ΔG Hads is found, with d-states closer to the Fermi level leading to strong hydrogen adsorption. Overall this work highlights the relevance of MoS2 nanotubes as promising hydrogen evolution catalysts and explains trends in their activity using the energies of the electronic states involved in binding hydrogen.

Enhancing the hydrogen evolution activity of MoS2 basal planes and edges using tunable carbon-based supports.

The hydrogen adsorption free energy (ΔGHads) on the basal plane and edges of MoS2 is studied using periodic density functional theory, with the catalyst supported by a range of two-dimensional carbon-based materials. Understanding how ΔGHads can be tuned with support gives insight into MoS2 as a catalyst for the hydrogen evolution reaction. The supports studied here include graphene oxide materials, heteroatom doped (S, B, and N) graphene, and some insulator materials (hexagonal boron nitride and graphitic carbon nitride). For the basal plane of MoS2, a wide range of values for ΔGHads are observed (between 1.4 and 2.2 eV) depending on the support material used. It is found that ΔGHads relates directly to the energy of occupied p-orbital states in the MoS2 catalyst, which is modified by the support material. On the Mo-edge of MoS2, different supports induce smaller variations in ΔGHads, with values ranging between -0.27 and 0.09 eV. However, a graphene support doped with graphitic N atoms produces a ΔGHads value of exactly 0 eV, which is thermodynamically ideal for hydrogen evolution. Furthermore, ΔGHads is found to relate closely and linearly to the amount of charge transfer between MoS2 and support when they adhere together. The support-induced tuning of ΔGHads on MoS2 observed here provides a useful tool for improving current MoS2 catalysts, and the discovery of variables which mediate changes in ΔGHads contributes to the rational design of new hydrogen evolution catalysts.

Social communication deficits in disruptive primary-school children.

BACKGROUND: Parent and teacher data, from questionnaire surveys, suggest that school-identified disruptive children often have pragmatic language deficits of an autistic type. AIMS: This replication study aimed to confirm earlier findings, using individual clinical assessment to investigate traits of autism-spectrum disorder in disruptive children. METHOD: Persistently disruptive children (n = 26) and a comparison group (n = 22) were recruited from primary schools in a deprived inner-city area. Measures included standardised autism diagnostic interviews (with parents) and tests of IQ, social cognition, theory of mind and attention (with children). RESULTS: The disruptive children possessed poorer pragmatic language skills (P<0.0001) and mentalising abilities (P<0.05) than comparisons. Nine disruptive children (35%) met ICD-10 criteria for atypical autism or Asperger syndrome. CONCLUSIONS: Many persistently disruptive children have undetected disorders of social communication, which are of potential aetiological significance.

The quality of life of young people with Tourette syndrome.

BACKGROUND: The study examined a UK sample of 57 young people with Tourette syndrome (TS). AIMS: The purpose of this study was to consider the impact of TS on young people's Quality of Life (QoL). METHODS: The study used a mixed methods design, combining focus groups and questionnaire data. Child report questionnaires measured QoL and TS symptom severity. RESULTS: The results showed that the QoL of children with TS was significantly worse than that of children in a UK normative sample. Analysis of transcripts from the groups identified four main themes; 'TS can be distressing and disabling', 'struggling to fit into society's expectations of normal behaviour', 'needing to control tics' and 'TS is one part of who I am'. CONCLUSIONS: Poorer QoL was associated with increased symptom severity in terms of tics, Attention Deficit Hyperactivity Disorder diagnosis and obsessive compulsive behaviours.

Effect of the presence or absence of J chain on expression of recombinant anti-Kell immunoglobulin M.

The aim of this study was to determine the effect of expressing a recombinant anti-Kell immunoglobulin (Ig) M from two cell lines, CH0 and NS0, on its ability to function as a diagnostic antibody. As a polymeric immunoglobulin, IgM is able to directly agglutinate red blood cells (RBCs), making it a useful blood grouping reagent. To simplify expression, recombinant human IgM (rIgM) from NS0 (a mouse myeloma line) and CHO (Chinese hamster ovary line) cells was expressed in the absence of human J chain. Whereas NS0 expresses mouse J chain, rIgM expressed from CH0 cells lack J chain. Although the ability to polymerize resides within the tailpiece of IgM heavy chain, J chain can influence the polymeric state. This in turn could affect the ability of rIgM to bind its antigen. The variable region of the heavy chain of an anti-Kell IgG was grafted onto the constant region of human IgM and co-expressed with light chain derived from the same antibody. rIgM was purified from each cell line and the strength of direct agglutination assessed. Both cell lines produced polymeric rIgM that was able to specifically bind the target antigen and to directly agglutinate RBCs to the same degree. The presence or absence of J chain did not affect the ability of the rIgM to bind the Kell antigen or the strength of agglutination. The presence of J chain is not required for the production of a functional rIgM for use as a diagnostic reagent. CHO and NS0 lines are both suitable for production of such a reagent.

Estimating False Positive Contamination in Crater Annotations from Citizen Science Data.

Web-based citizen science often involves the classification of image features by large numbers of minimally trained volunteers, such as the identification of lunar impact craters under the Moon Zoo project. Whilst such approaches facilitate the analysis of large image data sets, the inexperience of users and ambiguity in image content can lead to contamination from false positive identifications. We give an approach, using Linear Poisson Models and image template matching, that can quantify levels of false positive contamination in citizen science Moon Zoo crater annotations. Linear Poisson Models are a form of machine learning which supports predictive error modelling and goodness-of-fits, unlike most alternative machine learning methods. The proposed supervised learning system can reduce the variability in crater counts whilst providing predictive error assessments of estimated quantities of remaining true verses false annotations. In an area of research influenced by human subjectivity, the proposed method provides a level of objectivity through the utilisation of image evidence, guided by candidate crater identifications.

Adaptation of the animal welfare assessment grid (AWAG) for monitoring animal welfare in zoological collections.

Animal welfare monitoring is an essential part of zoo management and a legal requirement in many countries. Historically, a variety of welfare audits have been proposed to assist zoo managers. Unfortunately, there are a number of issues with these assessments, including lack of species information, validated tests and the overall complexity of these audits which make them difficult to implement in practice. The animal welfare assessment grid (AWAG) has previously been proposed as an animal welfare monitoring tool for animals used in research programmes. This computer-based system was successfully adapted for use in a zoo setting with two taxonomic groups: primates and birds. This tool is simple to use and provides continuous monitoring based on cumulative lifetime assessment. It is suggested as an alternative, practical method for welfare monitoring in zoos.

A community randomized controlled clinical trial of mixed carotenoids and micronutrient supplementation of patients with acquired immunodeficiency syndrome.

OBJECTIVE: This clinical trial aims to evaluate if natural mixed carotenoids supplementation can improve the health and survival of acquired immunodeficiency syndrome (AIDS) patients. DESIGN: A placebo-controlled, prospective, randomized, double-blind, multicenter clinical trial. SETTING: Community, tertiary care human immunodeficiency virus (HIV) clinics of the Canadian HIV Trials Network (CTN). PARTICIPANTS: Three hundred and thirty-one adults with advanced AIDS on conventional management were recruited during routine clinic visits. INTERVENTIONS: All participants, including 166 controls, received daily oral specially formulated multivitamins including vitamin A and trace elements; 165 treatment group participants received additional daily oral natural mixed carotenoids, equivalent to 120,000 IU (72 mg) of beta-carotene daily. Follow-up was quarterly at routine clinic visits. RESULTS: Mean (s.d.) follow-up was for 13 (6) months. Thirty-six participants died by 18 months. Serum carotene concentration <1.0 micromol/l was present in 16% participants at baseline. Despite variation in carotene content of the treatment medication, serum carotene concentrations increased significantly to twice the baseline levels to 18 months follow-up in participants who received carotenoids treatment compared with controls (P < 0.0001). Although not statistically significant, mortality was increased in participants who did not receive carotenoids treatment compared with those who did (HR time to death 1.76, 95% CI 0.89, 3.47, P = 0.11). In multivariate analysis, survival was significantly and independently improved in those with higher baseline serum carotene concentrations (P = 0.04) or higher baseline CD4 T-lymphocyte counts (P = 0.005). Adjusted mortality was also significantly and independently increased in those who did not receive carotenoids treatment compared with those who did (HR time to death 3.15, 95% CI 1.10, 8.98, P = 0.03). CONCLUSIONS: Low serum carotene concentration is common in AIDS patients and predicts death. Supplementation with micronutrients and natural mixed carotenoids may improve survival by correction of a micronutrient deficiency. Further studies are needed to corroborate findings and elucidate mechanism of action.

A demographic approach to monitoring the health of coral reefs.

Inshore coral reefs adjacent to the wet tropics in North Queensland, Australia, are regularly exposed to flood plumes from coastal river systems. Changes in the nature of these plumes have been linked to the declining health of coral reefs in the region. The effect of flood plumes on the health of inshore corals was investigated by quantifying aspects of the demography of populations of corymbose and digitate Acropora at three groups of Island reefs along a gradient of exposure and decreasing water quality (High Island >Frankland's >Fitzroy). The size-structures of colonies, the rates of sexual recruitment, and the growth and survival of juveniles, all varied among the Island reefs. Juvenile and adult sized colonies were far more abundant at the Fitzroy Island reefs, than at the High or Frankland Island reefs that were more exposed to flood plumes. Additionally, there were up to eight times as many sexual recruits at the Fitzroy Island reefs, compared with the High Island reefs. However, the rates of growth and survival of the juvenile sized corals at the Fitzroy Island reefs were lower than at the more exposed reefs. The comparatively low abundance of adult corals at the exposed reefs is most likely due to their histories of disturbance from crown-of-thorns and coral bleaching, but the lack of subsequent recovery due to their low levels of larval recruitment. If a stock-recruitment relationship is typical for these groups of reefs, then the low rates of recruitment may be linked to the low density of adult colonies. Alternately, direct or indirect effects of chronic exposure to poor water quality may have resulted in less suitable substrata for larval settlement. We discuss these results and provide examples of how information about population structure and dynamics can be used in simple matrix models to quantify the current and future health of populations of corals under various scenarios.

An assessment of career satisfaction among a group of general dental practitioners in Staffordshire.

OBJECTIVES: To assess the level of job satisfaction among general dental practitioners from one area of England, and to assess the association of various personal and work related factors with job satisfaction. DESIGN: Postal questionnaire survey. SETTING: General dental practices in South Staffordshire, Wolverhampton and Dudley, England. METHOD: An anonymous questionnaire posted to all 396 registered dentists in the above areas. RESULTS: A 75% response rate was achieved. Data were analysed using non-parametric statistics for any significant differences in the scores for stress, respect, overall professional satisfaction, quality of life and overall job satisfaction according to the different demographic groupings of the dentists (alpha =0.05). Dentists with an area of special interest had higher scores in all categories except quality of life. Overall job satisfaction was higher among private dentists, and those in group practices and in non-rural locations. The highest bi-variate correlation occurred between overall job satisfaction and overall professional satisfaction, delivery of care, income, respect and professional time. CONCLUSIONS: Job satisfaction was judged to be good among this group. Stress was the factor associated with the greatest dissatisfaction. This survey produced similar results to preceding US studies, and suggests ways of improving job satisfaction.