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Due to the risk of intracranial aneurysm (IA) recurrence and the potential requirement for re-treatment following endovascular treatment (EVT), radiological follow-up of these aneurysms is necessary. There is little evidence to guide the duration and frequency of this follow-up. The aim of this study was to establish the current practice in neurosurgical units in the UK and Ireland.A survey was designed with input from interventional neuroradiologists and neurosurgeons. Neurovascular consultants in each of the 30 neurosurgical units providing a neurovascular service in the UK and Ireland were contacted and asked to respond to questions regarding the follow-up practice for IA treated with EVT in their department.Responses were obtained from 28/30 (94%) of departments. There was evidence of wide variations in the duration and frequency of follow-up, with a minimum follow-up duration for ruptured IA that varied from 18 months in 5/28 (18%) units to 5 years in 11/28 (39%) of units. Young patient age, previous subarachnoid haemorrhage and incomplete IA occlusion were cited as factors that would prompt more intensive surveillance, although larger and broad-necked IA were not followed-up more closely in the majority of departments.There is a wide variation in the radiological follow-up of IA treated with EVT in the UK and Ireland. Further standardisation of this aspect of patient care is likely to be beneficial, but further evidence on the behaviour of IA following EVT is required in order to inform this process.

Delayed cerebral ischaemia (DCI) is a significant complication of aneurysmal subarachnoid haemorrhage (aSAH) and is strongly associated with poorer outcome. The Alberta Stroke Program Early Computer Tomography (ASPECT) score is an established scoring tool, used in acute ischaemic stroke, to quantify early ischaemic changes on CT head scans. We aim to identify if ASPECT scoring correlates with functional outcome in DCI following aSAH. Retrospective case–control study. Inclusion criteria: admission to the Department of Neurosurgery at Leeds Teaching Hospitals NHS Trust (a tertiary neurosurgical centre in the United Kingdom) between 2014 and 2018, with a diagnosis of anterior circulation aneurysmal subarachnoid haemorrhage; as confirmed by initial CT scan and subsequent CT angiography or catheter digital subtraction angiography. Cases were those who developed DCI (n = 43) and controls were randomly selected from those who did not develop DCI (n = 46) but otherwise met the same inclusion criteria. The primary outcome measure was Glasgow Outcome Score (GOS): assessed at discharge and 3 months. ASPECT scores were calculated from non-contrast CT head scans by three researchers blinded to each other and clinical outcome. Spearman’s rank correlation was used to calculate correlation between ASPECT scores and GOS. ASPECT score positively correlated with GOS in the cases both at discharge (Spearman rho 0.436, p = 0.003) and at 3 months (Spearman rho 0.431, p = 0.004). When corrected for Fisher grading, the adjusted odds ratio of having a high GOS with a low ASPECT score at discharge was OR 0.74 (95% CI 0.61–0.94, p = 0.003), and 3 months OR 0.73 (95% CI 0.59–0.91, p = 0.005). ASPECT score significantly correlates with clinical outcome in DCI post aSAH, even after correcting for Fisher grade. ASPECT scoring may identify patients at risk of poor outcome following DCI and represents a quick and reliable tool that aids in clinical decision-making and prognostication.

Emotional stress is a leading risk factor in the development of neuropsychiatric disorders possibly via immune activation. P2X7 receptors promote neuroinflammation, and research suggests a relationship between chromosome region 12q2431, in which the P2X7R gene is located, and development of mood disorders, however, few studies concentrate on its association with anxiety. Our aim was to investigate the effects of P2RX7 variation in interaction with early childhood traumas and recent stressors on anxiety. 1752 participants completed questionnaires assessing childhood adversities and recent negative life events, provided data on anxiety using the Brief Symptom Inventory, and were genotyped for 681 SNPs in the P2RX7 gene, 335 of which passed quality control and were entered into linear regression models followed by a linkage disequilibrium-based clumping procedure to identify clumps of SNPs with a significant main or interaction effect. We identified a significant clump with top SNP rs67881993 and containing a set of 29SNPs that are in high LD, which significantly interacted with early childhood traumas but not with recent stress conveying a protective effect against increased anxiety in those exposed to early adversities. Our study demonstrated that P2RX7 variants interact with distal and more etiological stressors in influencing the severity of anxiety symptoms, supporting previous scarce results and demonstrating its role in moderating the effects of stress.

Background Efforts to develop neuroimaging-based biomarkers in major depressive disorder (MDD), at the individual level, have been limited to date. As diagnostic criteria are currently symptom-based, MDD is conceptualized as a disorder rather than a disease with a known etiology; further, neural measures are often confounded by medication status and heterogeneous symptom states. Methods We describe a consortium to quantify neuroanatomical and neurofunctional heterogeneity via the dimensions of novel multivariate coordinate system (COORDINATE-MDD). Utilizing imaging harmonization and machine learning methods in a large cohort of medication-free, deeply phenotyped MDD participants, patterns of brain alteration are defined in replicable and neurobiologically-based dimensions and offer the potential to predict treatment response at the individual level. International datasets are being shared from multi-ethnic community populations, first episode and recurrent MDD, which are medication-free, in a current depressive episode with prospective longitudinal treatment outcomes and in remission. Neuroimaging data consist of de-identified, individual, structural MRI and resting-state functional MRI with additional positron emission tomography (PET) data at specific sites. State-of-the-art analytic methods include automated image processing for extraction of anatomical and functional imaging variables, statistical harmonization of imaging variables to account for site and scanner variations, and semi-supervised machine learning methods that identify dominant patterns associated with MDD from neural structure and function in healthy participants. Results We are applying an iterative process by defining the neural dimensions that characterise deeply phenotyped samples and then testing the dimensions in novel samples to assess specificity and reliability. Crucially, we aim to use machine learning methods to identify novel predictors of treatment response based on prospective longitudinal treatment outcome data, and we can externally validate the dimensions in fully independent sites. Conclusion We describe the consortium, imaging protocols and analytics using preliminary results. Our findings thus far demonstrate how datasets across many sites can be harmonized and constructively pooled to enable execution of this large-scale project.

Background There is limited evidence to direct the management of unruptured intracranial aneurysms. Models extrapolated from existing data have been proposed to guide treatment recommendations. The aim of this study is to assess whether a consensus-based treatment score (UIATS) or rupture rate estimation model (PHASES) can be used to benchmark UK multi-disciplinary team (MDT) practice. Methods Prospective data was collected on a consecutive series of all patients with unruptured intracranial aneurysms (UIAs) presenting to a major UK neurovascular centre between 2012 and 2015. The agreement between the UIATS and PHASES scores, and their sensitivity and specificity in predicting the real-world MDT outcome were calculated and compared. Results A total of 366 patients (456 aneurysms) were included in the analysis. The agreement between UIATS and MDT recommendation was low (weighted kappa 0.26 [95% CI 0.19, 0.32]); sensitivity and specificity were also low at 36% and 52% respectively. Groups that the MDT allocated to treatment, equipoise or no treatment had significantly different PHASES scores (p = 0.004). There was no significant difference between the two scores when predicting patients for whom MDT outcome was to recommend aneurysm treatment, but the UIATS score was superior in predicting patients who received an MDT recommendation of ‘treatment-equipoise’, or ‘not-for-treatment’ (AUC of 0.73 compared to 0.59 for PHASES). Conclusions The models studied failed to agree with the consensus view of multi-disciplinary team in a major neurovascular centre. We conclude that decision support tools such as the UIATS and PHASES scores should not be blindly introduced in respective institutions without prior internal validation, as they may not represent the local reality.

Objectives A combination of negatively biased information processing and a reduced ability to experience positive emotions can persist into remission from major depression (rMDD). Studies have shown that mindfulness-based cognitive therapy (MBCT) can increase self-reported positive emotions in rMDD participants; similar changes using neuropsychological tasks have not been shown. In this study, we investigated neuropsychological change in emotional processing following MBCT in rMDD participants. Methods Seventy-three rMDD participants, 40 of whom received MBCT and 33 of whom continued with treatment as usual (TAU), and 42 never depressed participants took part; neither the TAU nor never depressed participants received MBCT. All were assessed at baseline and immediately following MBCT or after an 8-week gap for those without active intervention. Participants completed emotion evaluation and face emotion recognition tasks with self-report measures (mood, mindfulness) at each session. Results Results showed an MBCT-specific shift in ratings from less negative to more positive emotion evaluations, which correlated with mindfulness practice and self-report mindfulness change. Both the MBCT and TAU groups showed a small increase in overall face emotion recognition accuracy compared with no change in never depressed participants. Conclusions These findings support a specific role for MBCT in encouraging more positive evaluations of life situations in those with previous depression rather than influencing lower-level processing of emotions. Results should be interpreted cautiously given that this was a non-randomised, preference choice trial. Trial Registration NCT02226042

Extreme climate events, including flooding and prolonged drought, may establish long-lasting (legacy) effects on soil abiotic and biotic properties, potentially influencing soil N-cycling, microbial communities, and plant productivity. Nitrogen (N) fertilizer often stimulates plant growth, but it remains unknown whether N addition can alleviate the impact of legacy drought or waterlogging events on crops. Our aim was to assess the interactive effects of legacy extreme climate events and N-addition on these processes. Using cotton as a model system, soils previously exposed to waterlogging and prolonged drought were used to examine potential legacy impacts of extreme climate on soil N process rates, abundance and structure of associated microbial communities, and cotton growth and productivity under different levels of N fertilizer application (0, 100, 200 and 300 kg N/ha). The deleterious legacy effects of prolonged drought on plant productivity were due to negative impacts on microbial abundance and community structure, and soil nutrient availability, thereby negatively influencing the rate of nitrification, and consequently plant available N. The legacy impacts of prolonged drought persisted throughout the experiment despite fertiliser applications of up to 300 kg of N/ha. The only observed legacy impacts of waterlogging were low NO3− levels in soils without N-addition and shifts in the abundance and structure of the N2O-reducing community. There were strong legacy impacts of prolonged drought, but minor legacy impacts of waterlogging, on soils and crop yields which could not be fully counteracted by the high rates of N fertilizer application. This study provides critical knowledge contributing to the development of adaptation and soil N management strategies to minimize the loss of farm productivity, within the context of increased frequencies and intensities of extreme weather events.

The rate of CO2 diffusion from soils to the atmosphere (soil CO2 efflux, soil respiration; Rsoil) reflects the integrated activity of roots and microbes and is among the largest fluxes of the terrestrial global C cycle. Most experiments have demonstrated that Rsoil increases by 20–35% following the exposure of an ecosystem to an atmosphere enriched in CO2 (i.e., eCO2), but such experiments have largely been performed in young and N-limited ecosystems. Here, we exposed a mature and phosphorus-limited eucalypt woodland to eCO2 and measured Rsoil across three full years with a combination of manual surveys and automated measurements. We also implemented an empirical model describing the dependence of Rsoil on volumetric soil water content (θ) and soil temperature (Tsoil) to produce annual Rsoil flux estimates. Rsoil varied strongly with Tsoil, θ, and precipitation in complex and interacting ways. The realized long-term (weeks to years) temperature dependence (Q10) of Rsoil increased from ~ 1.6 at low θ up to ~ 3 at high θ. Additionally, Rsoil responded strongly and rapidly to precipitation events in a manner that depended on the conditions of θ and Tsoil at the beginning of the rain event; Rsoil increased by up to 300% within 30 min when rain fell on dry soil that had not experience rain in the preceding week, but Rsoil was rapidly reduced by up to 70% when rain fell on wet soil, leading to flooding. Repeated measures analysis of Rsoil observations over 3 years indicated no significant change in response to CO2 enrichment (P = 0.7), and elevated CO2 did not alter the dependence of Rsoil on Tsoil or θ. However, eCO2 increased Rsoil observations by ~ 10% under some constrained and moderate environmental conditions. Annual Rsoil flux sums estimated with an empirical model were ~ 7% higher in eCO2 plots than in aCO2 plots, but this difference was not statistically significant. The lack of a large eCO2 effect on Rsoil is consistent with recent evidence that aboveground net primary production was not stimulated by eCO2 in this ecosystem. The C budget of this mature woodland may be less affected by eCO2 than the young N-limited ecosystems that have been studied previously.

Waterlogging may affect soil nitrification rates, resulting in changes in plant-available nitrogen (N), and hence potentially influencing crop productivity. Because nitrification is a microbially-driven process and ammonia-oxidizing communities regulate soil nitrification rates, the aim of this study was to investigate the mechanistic response of ammonia-oxidizing communities and nitrification rates to waterlogging. A field study was conducted by experimentally imposing two short-term waterlogging events when cotton plants were at the early- and late-flowering stages. Soil physicochemical properties, nitrification rates, and ammonia-oxidizing community abundance and structure in response to waterlogging were examined. Soil nitrate (NO3−) content, potential nitrification rates (PNR) and the abundance of ammonia-oxidizing communities significantly decreased upon waterlogging. Shifts in ammonia-oxidizing community structure were also observed. Both ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) responded to waterlogging. PNR was significantly correlated with the abundance and structure of both AOB and AOA. Waterlogging had strong negative effects on soil nitrification rates by altering the ammonia-oxidizing community abundance and structure, resulting in reduced soil N availability. Decreased plant-available N is likely to negatively affect primary productivity.

Multiple ectomycorrhizal fungi (EMF) compete to colonise the roots of a host plant, but it is not known whether their success is under plant or fungal control, or a combination of both. We assessed whether plants control EMF colonisation by preferentially allocating more carbon to more beneficial partners in terms of nitrogen supply or if other factors drive competitive success. We combined stable isotope labelling and RNA-sequencing approaches to characterise nutrient exchange between the plant host Eucalyptus grandis and three Pisolithus isolates when growing alone and when competing either indirectly (with a physical barrier) or directly. Overall, we found that nitrogen provision to the plant does not explain the amount of carbon that an isolate receives nor the number of roots that it colonises. Differences in nutrient exchange among isolates were related to differences in expression of key fungal and plant nitrogen and carbon transporter genes. When given a choice of partners, the plant was able to limit colonisation by the least cooperative isolate. This was not explained by a reduction in allocated carbon. Instead, our results suggest that partner choice in EMF could operate through the upregulation of defence-related genes against those fungi providing fewer nutrients.

Wollemi pine (Wollemia nobilis Jones, Hill & Allen) is a critically endangered conifer and living fossil. Translocation has been proposed as a conservation strategy to establish ‘back-ups’ to the wild population; however, knowledge regarding the environmental and biotic requirements of individuals planted in new environments is limited. An experimental translocation was established in a new location in the wild with Wollemi pines planted along a light and elevation gradient. Specific abiotic soil properties and associated microbial communities were linked to Wollemi pine performance in these new locations to inform best practice for future translocations. Our results indicate that soil properties can be used to select appropriate translocation sites that ensure initial establishment and growth. One year after translocation Wollemi pine had recruited a species-specific fungal community that persisted. Species-specific bacterial communities in their soil and roots formed in the second year after planting. Translocated Wollemi pines that were unhealthy and were not growing did not have the species-specific fungal community. The long-term functional consequence of this species-specific microbial community warrants ongoing investigation. This is one of the first studies to explicitly consider the role of microbial communities during the translocation of a rare plant and such approaches will be valuable for informing best translocation practice for other rare plant species.

Elevated CO2 (CE) and temperature (TE) can not only affect crop physiology and growth but also soil nutrient availability, which could in turn influence crop response to CE and TE. However, such indirect impacts of CE and TE on crop productivity are often unexplored, potentially underestimating the impact of CE and TE at a system level. To explore the possible role of soil nutrient availability in mediating crop responses to CE and TE, we examined the effects of CE and TE on cotton productivity and soil nutrient availability in two soils. Early vegetative growth response was dominated by the interaction between CE and TE; TE accelerated vegetative growth while CE enhanced photosynthesis and vegetative growth at ambient temperature. When soil nitrogen availability became low during the reproductive phase, altered soil nitrogen availability at CE and TE and differences in soil characteristics influenced resource allocation and yield response, resulting in a doubling of cotton yield at TE but only a marginal increase at CE. Changes in soil nutrient availability induced by CE and TE during crop development can enhance or limit yield responses to CE and TE. Thus, soil responses should also be considered when developing adaptation strategy for climate change.

Interpersonal trust and distrust are important components of human social interaction. Although several studies have shown that brain function is associated with either trusting or distrusting others, very little is known regarding brain function during the control of social attitudes, including trust and distrust. This study was designed to investigate the neural mechanisms involved when people attempt to control their attitudes of trust or distrust toward another person. We used a novel control-of-attitudes fMRI task, which involved explicit instructions to control attitudes of interpersonal trust and distrust. Control of trust or distrust was operationally defined as changes in trustworthiness evaluations of neutral faces before and after the control-of-attitudes fMRI task. Overall, participants (n = 60) evaluated faces paired with the distrust instruction as being less trustworthy than faces paired with the trust instruction following the control-of-distrust task. Within the brain, both the control-of-trust and control-of-distrust conditions were associated with increased temporoparietal junction, precuneus (PrC), inferior frontal gyrus (IFG), and medial prefrontal cortex activity. Individual differences in the control of trust were associated with PrC activity, and individual differences in the control of distrust were associated with IFG activity. Together, these findings identify a brain network involved in the explicit control of distrust and trust and indicate that the PrC and IFG may serve to consolidate interpersonal social attitudes.

There is increasing evidence that genetic factors have a role in differential susceptibility to depression in response to severe or chronic adversity. Studies in animals suggest that nitric oxide (NO) signalling has a key role in depression-like behavioural responses to stress. This study investigated whether genetic variation in the brain-expressed nitric oxide synthase gene NOS1 modifies the relationship between psychosocial stress and current depression score. We recruited a population sample of 1222 individuals who provided DNA and questionnaire data on symptoms and stress. Scores on the List of Life-Threatening Experiences (LTE) questionnaire for the last year and self-rated current financial hardship were used as measures of recent/ongoing psychosocial stress. Twenty SNPs were genotyped. Significant associations between eight NOS1 SNPs, comprising two regional haplotypes, and current depression score were identified that survived correction for multiple testing when current financial hardship was used as the interaction term. A smaller three-SNP haplotypes (rs10507279, rs1004356 and rs3782218) located in a regulatory region of NOS1 showed one of the strongest effects, with the A-C-T haplotype associating with higher depression scores at low adversity levels but lower depression scores at higher adversity levels (p=2.3E-05). These results suggest that NOS1 SNPs interact with exposure to economic and psychosocial stressors to alter individual's susceptibility to depression.

Stakeholders are often required to make judgments and decisions about the tradeoffs between multiple competing objectives inherent in any engineering design. Design optimization can provide decision support for such situations, but often prescribes that only a single design solution be selected for a given set of preferences. The purpose of this study is to frame an objective function for assessing how the sensitivity of one objective relative to another varies in space and to demonstrate the method using a real site, with spatially-dependent floodplain access and bridge scour as the objective tradeoffs. Bridge scour is a widespread and expensive infrastructure problem, and the proposed methodology provides the ability to assess how the sensitivity of bridge scour to floodplain access varies at different locations in a river reach. The site chosen for demonstration purposes was the Lewis Creek in the vicinity of the Quinlan Covered Bridge in Charlotte, VT. Differential evolution (DE) was wrapped around an existing HEC-RAS model. The decision variables corresponded to floodplain access at locations up and downstream of the bridge; the objective function was constructed so that optimal solutions may be interpreted as relative salience of floodplain access to bridge scour. Multiple weightings of the objectives were used to verify that the rank-order of locations was robust. The optimal DE solutions for all weightings resulted in the same sensitivity ranking of locations, providing evidence that the analysis is not dependent on a particular choice of stakeholder objective weightings. For systems with spatially dependent variables that impact a constraint or objective of interest to stakeholders, a tool for identifying locations where that variable has a particularly strong or weak impact (e.g. where floodplain access is more or less important for bridge scour) has obvious advantages. This study demonstrates a method for conducting such a sensitivity analysis using a numerical optimization scheme. On the real test site, the sensitivity ranking was consistent across multiple stakeholder weightings, providing evidence that the technique is robust, and one that can be used at multiple stages of design. This work demonstrates the utility of a novel interpretation of optimization results in which locations are ranked according to the relative sensitivity of competing objectives.

BackgroundPeople with depression are usually managed in primary care and antidepressants are often the first-line treatment, but only one third of patients respond fully to a single antidepressant. This paper describes the protocol for a randomized controlled trial (MIR) to investigate the extent to which the addition of the antidepressant mirtazapine is effective in reducing the symptoms of depression compared with placebo in patients who are still depressed after they have been treated with a Selective Serotonin Reuptake Inhibitor (SSRI) or Serotonin and Noradrenaline Reuptake Inhibitor (SNRI) for at least six weeks in primary care.Methods/DesignMIR is a two parallel group, multi-centre, pragmatic, placebo controlled, randomised trial with allocation at the level of the individual. Eligible participants are those who: are aged ≥18 years; are currently taking an SSRI/SNRI antidepressant (for at least 6 weeks at an adequate dose); score ≥14 on the Beck Depression Inventory (BDI-II); have adhered to their medication; and meet ICD-10 criteria for depression (assessed using the Clinical Interview Schedule-Revised). Participants who give written, informed consent, will be randomized to receive either oral mirtazapine or matched placebo, starting at 15mg daily for 2 weeks and increasing to 30mg daily thereafter, for up to 12 months (to be taken in addition to their usual antidepressant). Participants, their GPs, and the research team will all be blind to the allocation. The primary outcome will be depression symptoms at 12 weeks post-randomisation, measured as a continuous variable using the BDI-II. Secondary outcomes (measured at 12, 24 and 52 weeks) include: response (reduction in depressive symptoms (BDI-II score) of at least 50% compared to baseline); remission of depression symptoms (BDI-IIDiscussionThe MIR trial will provide evidence on the clinical and cost-effectiveness of mirtazapine as an adjunct to SSRI/SNRI antidepressants for patients in primary care who have not responded to monotherapy. Trial registration: EudraCT Number: 2012-000090-23 (Registered Jan 2012); ISRCTN06653773 (Registered Sept 2012)Funding: National Institute for Health Research (Health Technology Assessment)

Reduced hippocampal volume has been reported in depression and may be involved in the aetiology of depressive symptoms and vulnerability to depressive relapse. Neuroplasticity following antidepressant drug treatment in the hippocampus has been demonstrated in animal models but adaptive changes after such treatment have not been shown in humans. In this study, we determined whether grey matter loss in the hippocampus in depression (1) is present in medication-free depressed (2) changes in response to antidepressant treatment and (3) is present as a stable trait in medication-free remitted patients. Sixty-four medication-free unipolar depressed patients: 39 currently depressed and 25 in remission, and 66 healthy controls (HC) underwent structural magnetic resonance imaging in a cross-sectional and longitudinal design. Thirty-two currently depressed participants were then treated with the antidepressant citalopram for 8 weeks. Adherence to treatment was evaluated by measuring plasma citalopram concentration. We measured regional variation in grey matter concentration by using voxel-based morphometry-Diffeomorphic Anatomical Registration Through Exponentiated Lie algebra. Patients with current depression had bilaterally reduced grey matter in the hippocampus compared with HC and untreated patients in stable remission with the latter groups not differing. An increase in grey matter was observed in the hippocampus following treatment with citalopram in currently depressed patients. Grey matter reduction in the hippocampus appears specific to the depressed state and is a potential biomarker for a depressive episode.

In view of the close association between ericaceous shrubs and ectomycorrhizal trees in forest ecosystems, the interaction between ectomycorrhizal basidiomycetes and the hair roots of four typical ericoid mycorrhizal hosts was investigated in vitro. Seedlings of Vaccinium myrtillus, V. vitis-idaea, V. macrocarpon and Calluna vulgaris were inoculated with each of four ectomycorrhizal basidiomycetes from different phylogenetic groups (Laccaria bicolor, Lactarius musteus, Suillus variegatus and Tomentellopsis submollis) in a low carbon and nutrient agar-cellophane culture system. Two ericoid mycorrhizal Helotiales ascomycetes (Meliniomyces bicolor in the Rhizoscyphus ericae aggregate and a mycobiont out of the Rhizoscyphus ericae aggregate) were included for comparison. Interactions between fungi and hair roots ranged from neutral to surface attachment, and the formation of intracellular hyphal coils. Root and shoot responses to inoculation were different between the host/fungus combinations. The ectomycorrhizal fungus L. bicolor formed extensive intracellular colonization, spreading cell-to-cell with multiple hyphal entry points and intracellular hyphal coils with single entry points in C. vulgaris and V. macrocarpon epidermal cells respectively, however, no significant effects on plant growth were detected. Meliniomyces bicolor formed intracellular hyphal coils in the epidermal cells of V. myrtillus and V. macrocarpon but not the other host spp. The M. bicolor isolate stimulate V. myrtillus root length about 2.5 times. Interestingly, although the unknown ascomycete strain out of the Rhizoscyphus ericae aggregate formed intracellular hyphal coils in epidermal cells of all host plants, it suppressed the growth of C. vulgaris, V. myrtillus, and V. vitis-idaea but not to V. macrocarpon. Further and more detailed experimentation under more ecological realistic conditions for a longer period of time is needed.

Active management to encourage the expansion of native pine woodland onto neighbouring moorland has been suggested as a tool to promote increases in forest area to combat climate change. Low intensity burning has previously been shown to increase pine seedling establishment, however the effect of this on below-ground diversity and functioning in these important terrestrial carbon stores is equivocal. Here, we assessed the effect of a single burn and grazing exclosures after a 6 year period on soil microbial respiratory activity and fungal community structure using terminal restriction fragment polymorphism (T-RFLP) analysis. The combined data suggest that the strategy of a single prescribed burn to facilitate Scots pine establishment had no lasting effect on either fungal taxonomic richness, fungal community composition or microbial activity. Thus, our findings support the proposed use of single, low intensity, prescribed burns in regenerating Scots pine forests as a low impact management tool.

An ultralow-thermal-conductivity compound with the ideal formula [(PbSe)1.00]1[MoSe2]1 has been successfully crystallized across a range of compositions. The lattice parameters varied from 1.246 nm to 1.275 nm, and the quality of the observed 00l diffraction patterns varied through the composition region where the structure crystallized. Measured resistivity values ranged over an order of magnitude, from 0.03 Ω m to 0.65 Ω m, and Seebeck coefficients ranged from −181 μV K−1 to 91 μV K−1 in the samples after the initial annealing to form the basic structure. Annealing of samples under a controlled atmosphere of selenium resulted in low conductivities and large negative Seebeck coefficients, suggesting an n-doped semiconductor. Scanning transmission electron microscopy cross-sections confirmed the interleaving of bilayers of PbSe with Se-Mo-Se trilayers. High-angle annular dark-field images revealed an interesting volume defect, where PbSe grew through a region where a layer of MoSe2 would be expected in the perfect structure. Further studies are required to correlate the density of these defects with the observed electrical properties.

The number of genetically distinct individuals within a community is a key component of biodiversity and yet its impact at different trophic levels, especially upon the diversity of functionally important soil microorganisms is poorly understood. Here, we test the hypothesis that plant communities that are genetically impoverished will support fewer species of root-associated fungi. We used established grassland mesocosms comprising non-sterile natural soil supporting defined communities of 11 clonally-propagated plant species. Half of the mesocosms contained one genotype per species and half 16 genotypes per species. After 8 years growth, we sampled roots from the mesocosms and measured root-associated fungal richness and diversity using terminal restriction fragment length polymorphism (T-RFLP). Contrary to our hypothesis, we found that the roots of genetically impoverished communities contained more species of fungi and had greater diversity compared to genetically rich communities. Analysis of the plant species composition of the mesocosm communities indicated that genotypic diversity affects root-fungal diversity indirectly through its influence upon plant species diversity. Our findings highlight the need to include feedbacks with plant intraspecific diversity into existing models describing the maintenance of soil biodiversity.

Purpose Commercial monoculture plantations of the native Australian Araucaria cunninghamii are common in subtropical and tropical Queensland and are generally established following clearing of native mixed forest. The consequences of such forest conversion for soil fungal communities, however, have not been assessed in detail.

Decision making, choosing the best option from the possible outcomes, is impaired in many psychiatric conditions including affective disorders. We tested the hypothesis that variations in serotonergic genes (TPH2, TPH1, SLC6A4, HTR1A), which influence serotonin availability, affect choice behavior in a probabilistic gambling task. A population cohort (N=1035) completed a paper-and-pencil gambling task, filled out personality and symptom questionnaires and gave consent for the use of their DNA in a genetic association study. A subgroup of subjects (N=69) also completed a computer version of the task. The gambling task was designed to estimate an individual's tendency to take a risk when choosing between a smaller but more certain 'win' and a larger, less probable one. We genotyped seven haplotype tagging SNPs in the TPH2 gene, and previously reported functional polymorphisms from the other genes (rs1800532, 5HTTLPR, and rs6295). Carriers of the more prevalent TPH2 haplotype, which was previously associated with less active enzyme variant, showed reduced risk taking on both tasks compared with subjects not carrying the common haplotype. The effect of TPH2 haplotypes on risk-taking was independent of current depression and anxiety symptoms, neuroticism and impulsiveness scores. We did not find an association between functional polymorphisms in the TPH1, SLC6A4, HTR1A genes and risk-taking behavior. In conclusion, our study demonstrates the role of the TPH2 gene and the serotonin system in risk taking and suggests that TPH2 gene may contribute to the expression of psychiatric phenotypes through altered decision making.

Samples of rhizosphere soil and bulk soil were collected from under Araucaria bidwillii in a tropical montane rainforest at Mount Lewis forest reserve, Queensland, Australia. DNA was extracted from soil and denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified partial rDNA internal transcribed spacer (ITS) regions of rhizosphere and bulk soil samples compared. Neither canonical analysis of the principal coordinates nor principal component analysis revealed clear separation of soil samples according to their origin in rhizosphere or bulk soil. Following amplification of rDNA ITS regions using the primers ITS1-F and ITS4, restriction fragment length polymorphism (RFLP) and sequence analyses were also used to identify fungal sequences that were present in clone assemblages from rhizosphere soil and bulk soil. A total of fifty-three RFLP types were thus identified, with the majority being ascomycetes and the remainder basidiomycetes or zygomycetes. Nine RFLP types had affinity with Mortierellaceae, and phylogenetic analysis indicated that these probably represent multiple Mortierella species in both rhizosphere and bulk soil samples. Similar evidence was obtained for the presence of multiple Trichosporon species. RFLP type 53 from a bulk soil sample was identified as a Soil Clone Group I ascomycete, confirming the widespread occurrence of this group.

Negative cognitive styles (habitual approaches to processing information) and neurotic personality traits reported in affective disorders may have important therapeutic implications in both bipolar and unipolar disorder. In particular, negative cognitive styles appear to predict risk of recurrence of affective disorder and poor therapy outcomes for depressed individuals. Previous research has reported relationships between negative cognitive styles and neuroticism, but none has explored the relative contributions of each prospectively in a mixed bipolar and unipolar sample. Therefore, we evaluated the contributions of negative cognitive style and personality (extraversion and neuroticism) in predicting symptoms and functioning in a sample of 199 participants with affective disorder (76 bipolar, 123 unipolar) and 124 participants at 6-month follow-up (55 bipolar, 69 unipolar). Participants completed self-report measures of negative cognitive style, personality, and quality of life, complemented by observer ratings of affective symptoms and global functioning. Negative cognitive style at baseline was predictive of worse global functioning and quality of life ratings at 6 months, but not of affective symptoms (better predicted by extraversion). Examining the bipolar and unipolar groups separately, negative cognitive style was predictive of 6-month outcomes in quality of life and global functioning in the unipolar group only. Personality did not predict symptomatic or functional outcomes at 6 months in this sample. Implications for therapy are considered.

Enhanced soil respiration in response to elevated atmospheric CO2 has been demonstrated, and ectomycorrhizal (ECM) fungi are of particular interest since they partition host-derived photoassimilates belowground. Although a strong response of ECM fungi to elevated CO2 has been shown, little is still known about the functional diversity among species. We studied carbon (C) partitioning in mycorrhizal Scots pine seedlings in response to short-term CO2 enrichment, using seven ECM species with different ecological strategies. Mycorrhizal associations were synthesised and seedlings grown in large Petri dishes containing peat:vermiculite and nutrient solution for 10–15 weeks, after which half of the microcosms were exposed to elevated CO2 treatment (710 ppm) for 15 days and the other half were kept in ambient CO2 treatment. Partitioning of C was quantified by pulse labelling the seedlings with 14CO2 and examining the distribution of labelled assimilates in shoot, root and extraradical mycelial compartments by destructive harvest and liquid scintillation counting. Fungal biomass was determined with PLFA analysis. The respiratory loss of 14CO2 was on average greater in the elevated CO2 treatment for most species compared to the ambient CO2 treatment. More label was retrieved in the shoots in the ambient CO2 treatment compared to elevated CO2 (significant for P. involutus and P. fallax). Greater amounts of label were found in the extraradical mycelial compartment in all species (except P. involutus) in elevated CO2 compared to ambient CO2 (significant for L. bicolor, P. byssinum, P. fallax and R. roseolus). Fungal biomass production increased significantly with elevated CO2 for two species (H. velutipes and A. muscaria); three species (P. fallax, P. involutus and R. roseolus) showed a similar but non-significant trend, whereas L. bicolor and P. byssinum produced less biomass in elevated CO2 compared to ambient CO2. When 14C in the mycelial compartment and respiration was expressed per unit fungal PLFA the difference between CO2 treatments disappeared. We demonstrated that different ECM fungal isolates respond differently in C partitioning in response to CO2 enrichment. These results suggest that under certain growth conditions, when nutrients are not limiting, ECM fungi respond rapidly to increasing C-availability through changed biomass production and respiration.

FragMatch is a user-friendly Java-supported program that automates the identification of taxa present in mixed samples by comparing community DNA fragment data against a database of reference patterns for known species. The program has a user-friendly Windows interface and was primarily designed for the analysis of fragment data derived from terminal restriction fragment length polymorphism analysis of ectomycorrhizal fungal communities, but may be adapted for other applications such as microsatellite analyses. The program uses a simple algorithm to check for the presence of reference fragments within sample files that can be directly imported, and the results appear in a clear summary table that also details the parameters that were used for the analysis. This program is significantly more flexible than earlier programs designed for matching RFLP patterns as it allows default or user-defined parameters to be used in the analysis and has an unlimited database size in terms of both the number of reference species/individuals and the number of diagnostic fragments per database entry. Although the program has been developed with mycorrhizal fungi in mind, it can be used to analyse any DNA fragment data regardless of biological origin. FragMatch, along with a full description and users guide, is freely available to download from the Aberdeen Mycorrhiza Group web page (http://www.aberdeenmycorrhizas.com).

Fe−Co composition gradient and Fe−Pt multilayer alloy films were tested as catalysts for groving vertically aligned carbon nanofibers (VACNFs) by plasma-enhanced chemical vapor deposition (PECVD). The Fe−Co film yielded nanofibers with alloy tips in a wide compositional range varying from 8.15 pct Fe at the Co-rich end to 46.29 pct Fe in the middle of the wafer as determined by energy-dispersive X-ray analysis. Two Fe−Co cubic phases (SG Pm3m, \({\text{P}}m\overline 3 m\) were identified by preliminary X-ray diffraction (XRD) measurements. Magnetic measurements showed a substantially greater hysteresis loop area and coercivity in Fe−Co catalyst nanoparticles as compared to the asdeposited Fe−Co film. The Fe−Pt film did not break into FePt alloy nanoparticles under the applied processing parameters and thus the utility of FePt as a VACNF catalyst has been inconclusive.

The oxidation behavior of a cast nickel aluminide alloy, IC221M, was examined after long-term aging in air for up to 16,600 hours at 900 °C and 5000 hours at 1100 °C. The oxidation products were identified using X-ray diffraction and energy-dispersive X-ray (EDX) spectroscopy with multivariate statistical analysis. At 900 °C, NiO dominates the oxidation products initially, but at longer times, NiAl2O4 spinel and Al2O3 predominate and remain stable for times up to 16,600 hours. Cross-sectional observation confirmed that a continuous surface oxide that is mostly a mixture of Al2O3 and NiAl2O4 protects the base metal. In its initial stages, the oxidation process at 1100 °C is qualitatively similar to that at 900 °C but with faster kinetics. However, as aging proceeds, NiO spalls freely from the surface, and a protective continuous oxide scale does not form. The oxidation mechanism can be qualitatively understood by the selective oxidation mechanism maps developed by Giggins and Pettit.

Serotonin (5-hydroxytryptamine, 5-HT) is implicated in the aetiology and treatment of a variety of psychiatric disorders. A limitation of research has been the necessity to use indirect measures of 5-HT function. We describe a method of analysing pharmacoMRI data using SPM and apply it to the direct i.v. infusion of selective 5-HT reuptake inhibitor, citalopram, in 12 healthy volunteers. Scanning took place on a 1.5-T Philips MRI scanner. Areas implicated in depression and its treatment were observed to have increasing signal with respect to time. These areas included the caudate, the amygdala, the hippocampus, the striatum and the thalamus. Direct pMRI using i.v. citalopram opens new ways of investigating 5-HT mechanism in depression and its treatment.

Olivine grain boundaries in deformed aggregates of olivine + basalt and partially molten lherzolite were analyzed with various electron microscopy techniques to test for the presence of thin (0.5–10 nm) intergranular melt films. High-resolution transmission electron microscopy (HREM) observations reveal that most of the boundaries do not contain a thin amorphous phase, although a small fraction of grains are separated by relatively thick (~1 µm) layers of melt. However, due to the anisotropy of the olivine-melt interfacial energy, melt often tapers from a triple junction into an adjoining grain boundary over a length of 1 to 2 µm, giving an effective dihedral angle of only ~2°. The chemistry of olivine-olivine grain boundaries was analyzed using energy dispersive X-ray (EDX) profiling by scanning transmission electron microscopy (STEM) with a probe size of

Rationale: Lesions of the orbital prefrontal cortex (OPFC) can cause pathologically impulsive behaviour in humans. Inter-temporal choice behaviour (choice between reinforcers differing in size, delay and/or probability) has been proposed as a model of "impulsive choice" in animals. Objective: The effect of lesions of the OPFC on rats' inter-temporal choice behaviour was examined in two experiments: (1) rats chose between a smaller immediate reinforcer and a larger delayed reinforcer; (2) rats chose between a smaller certain reinforcer and a larger probabilistic reinforcer. Methods: Under halothane anaesthesia, rats received injections of the excitotoxin quinolinate into the OPFC (0.1 M, 0.5 µl, two injections in each hemisphere), or sham lesions (injections of vehicle). They were trained to press two levers (A and B) for food-pellet reinforcers in discrete-trials schedules. In free-choice trials, a press on A resulted in immediate delivery of one food pellet; a press on B resulted in delivery of two pellets, either following a delay (d) (experiment 1), or with a probability (p)

Sudden unexpected deaths have been reported with antipsychotic use since the early 1960s. In some cases the antipsychotic may be unrelated to death, but in others it appears to be a causal factor. Antipsychotics can cause sudden death by several mechanisms, but particular interest has centred on torsade de pointes (TdP), a polymorphic ventricular arrhythmia that can progress to ventricular fibrillation and sudden death. The QTc interval is a heart rate-corrected value that represents the time between the onset of electrical depolarisation of the ventricles and the end of repolarisation. Prolongation of the QTc interval is a surrogate marker for the ability of a drug to cause TdP. In individual patients an absolute QTc interval of500 msec or an increase of 60 msec from baseline is regarded as indicating an increased risk of TdP. However, TdP can occur with lower QTc values or changes. Concern about a relationship between QTc prolongation, TdP and sudden death applies to a wide range of drugs and has led to the withdrawal or restricted labelling of several. Among antipsychotics available in the UK, sertindole was voluntarily suspended, droperidol was withdrawn, and restricted labelling introduced for thioridazine and pimozide. The degree of QTc prolongation is dose dependent and varies between antipsychotics reflecting their different capacity to block cardiac ion channels. Significant prolongation is not a class effect. Among currently available agents, thioridazine and ziprasidone are associated with the greatest QTc prolongation. Virtually all drugs known to cause TdP block the rapidly activating component of the delayed rectifier potassium current (I(kr)). Arrhythmias are more likely to occur if drug-induced QTc prolongation coexists with other risk factors, such as individual susceptibility, presence of congenital long QT syndromes, heart failure, bradycardia, electrolyte imbalance, overdose of a QTc prolonging drug, female sex, restraint, old age, hepatic or renal impairment, and slow metaboliser status. Pharmacodynamic and pharmacokinetic interactions can also increase the risk of arrhythmias. Further research is needed to quantify the risk of sudden death with antipsychotics. The risk should be viewed in the context of the overall risks and benefits of antipsychotic treatment. It seems prudent, where possible, to select antipsychotics that are not associated with marked QTc prolongation. If use of a QTc-prolonging drug is warranted, then measures to reduce the risk should be adopted.

A new synthesis route, based on internal oxidation reactions in multiphase alloys, is proposed for the controlled production of near-surface, complex ceramic-ceramic or ceramic-metallic composite structures. Using this approach, a microdispersion of a complex nitride perovskite, Cr3PtN, was formed in Cr2N or Cr(Pt) by internal nitridation of a two-phase Cr(Pt) + Cr3Pt precursor alloy. A framework for use of this phenomenon to synthesize island micro- (and potentially meso- or nano-) composite functional surface structures is presented.

The influence of various inorganic and organic nitrogen sources on biomass production by 17 isolates of Australian Pisolithus spp. was investigated before and after a 3-year maintenance period in axenic culture. While some isolates produced similar or higher amounts of biomass on NH4+ or certain amino acids after the maintenance period, there was a general trend to reduced biomass production on these substrates. Biomass production by most isolates on bovine serum albumin increased significantly after maintenance. The data are discussed in relation to the use of axenic culture growth experiments for investigations of inter- and intraspecific physiological variation in ectomycorrhizal fungi.

A meta-analysis of 20 short term comparative studies of 5 selective serotonin reuptake inhibitors (SSRIs; citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline) has shown no difference in efficacy between individual compounds but a slower onset of action of fluoxetine. There were suggestions that fluoxetine caused more agitation, weight loss and dermatological reactions than the other SSRIs. More patients discontinued fluvoxamine and fewer patients stopped sertraline because of adverse effects than their comparator SSRIs. The most common adverse reactions to the SSRIs were gastrointestinal (especially nausea) and neuropsychiatric (particularly headache and tremor). Data from the Committee on Safety of Medicines showed more reports of suspected reactions (including discontinuation reactions) to paroxetine, and of gastrointestinal reactions to fluvoxamine and paroxetine, than the other SSRIs during their first 2 years of marketing. Prescription-event monitoring revealed a higher incidence of adverse events related to fluvoxamine than its comparators. There were higher incidences of gastrointestinal symptoms, malaise, sedation and tremor during treatment with fluvoxamine and of sedation, tremor, sweating, sexual dysfunction and discontinuation reactions with paroxetine. Fluoxetine was not associated with a higher incidence of suicidal, aggressive and related events than the other SSRIs. Patients have survived large overdoses of each of the compounds, but concern has been expressed over 6 fatalities following overdoses of citalopram. Drug interactions mediated by cytochrome P450 enzymes are theoretically less likely to occur during treatment with citalopram and sertraline, but there is a sparsity of clinical data to support this. Methodological difficulties and price changes do not allow choice for recommendations on the choice of SSRI based on pharmacoeconomic data. Taking into account the strengths and weaknesses of the methods used to compare drugs, guidelines to the selection of individual SSRIs in clinical practice are proposed. Citalopram should be avoided in patients likely to take overdoses. Fluoxetine may not be the drug of first choice for patients in whom a rapid antidepressant effect is important or for those who are agitated, but it may have advantages over other SSRIs in patients who are poorly compliant with treatment and those who have previously had troublesome discontinuation symptoms. Fluvoxamine, and possibly paroxetine, should not be used as first choice in patients especially prone to SSRI-related adverse reactions, while paroxetine should be avoided if previous discontinuation of treatment was troublesome. When in doubt about the risks of drug interactions, citalopram or sertraline should be considered given the lower theoretical risk of interactions.

We report a case of SMV injury in a critically ill patient. The patient was a 19-year-old woman involved in a motor vehicle collision. Her injuries included grade II splenic and renal lacerations, devascularized and lacerated right and transverse colon, a transected transverse mesocolon, a massive shear injury of her abdominal wall, and two partial SMV transections. At initial damage control laparotomy, the SMV was ligated, the devascularized bowel resected and a temporary abdominal closure applied. At re-operation, a mesocaval shunt using saphenous vein was employed. The shunt failed and the patient required a saphenous vein jump graft. Although visceral vascular injuries are rare, ligation of the SMV in a damage control situation is acceptable. This case study is the first to discuss appropriate treatment when interruption to a patient's collateral visceral venous drainage limits the surgeon's ability to ligate. In these situations, bypass shunts may be successful.

The effect of simulated body fluid (SBF) on the structure and microstructure of ferrimagnetic bioglass ceramics (FBC) was investigated in series of samples in the system of the oxides [0.45(CaO, P2O5) (0.52-x)SiO2 xFe2O3 0.03Na2O], with X = 0.05, 0.10, 0.15, 0.20. Physical properties of the materials were studied as a function of processing parameters and time of immersion in SBF by x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS). The in vitro experiment showed that bioactivity of the FBC varies with the composition of the oxides, heat treatment, and time of exposure in SBF in a non-systematic way. A surface layer of Si, P, Ca partially covers the Fe, O dendrites, while formation and size of pores is determined by the specific processing parameters of the materials.

Nanoindentation experiments were performed on single crystals of (100) Si using a series of triangular pyramidal indenters with centerline-to-face angles in the range 35.3° to 85.0°. The influences of the indenter geometry on cracking and phase transformation during indentation were systematically studied. Although reducing the indenter angle reduces the threshold load for cracking and increases the crack lengths, c, at a given indention load, P, the frequently observed relation between P and c3/2 is maintained for all of the indenters over a wide range of load. Features in the nanoindentation load-displacement curves in conjunction with Raman spectroscopy of the crystalline and amorphous phases in and around the contact impression show that the indenter geometry also plays a role in the phase transformation behavior. Results are discussed in relation to prevailing ideas about indentation cracking and phase transformation in silicon.

Specimens of the cast Ni3Al alloy IC221M were annealed in air at 900°C to examine the effects of oxidation and thermal aging on the microstructure. The alloy is comprised of a dendritically solidified γ-γ′ matrix containing γ+Ni5Zr eutectic colonies in the interdendritic regions. Microstructures of aged specimens were examined by optical microscopy and energy dispersive X-ray (EDX) spectrum imaging in the scanning electron microscope (SEM). Two primary changes in the microstructures were observed: (1) there is considerable homogenization of the cast microstructures with aging, and (2) the volume fraction of the γ+Ni5Zr eutectic decreases. Oxidation products were identified using x-ray diffraction and EDX spectrum imaging with multivariate statistical analysis (MSA). During the initial stages of oxidation, the first surface oxide to form is mostly NiO with small amounts of Cr2O3, ZrO2, NiCr2O4, and θ-Al2O3. Initially, oxidation occurs primarily in the interdendritic regions due to microsegregation of alloying elements during casting. With further aging, a continuous film of α-Al2O3forms immediately beneath the surface that eventually evolves into a double layer of α-Al2O3and NiAl2O4. Although these oxides are constrained to the near surface region, others penetrate to greater depths facilitated by oxidation of the γ+Ni5Zr eutectic colonies. These oxides appear in the microstructure as long, thin spikes of ZrO2surrounded by a thin sheath of Al2O3.

This paper provides a review of recent progress on point defect and solute hardening in binary and ternary B2 intermetallics. As is the case for disordered metallic solutions, the presence of point defects and solute atoms in ordered intermetallic compounds results in solid solution hardening (SSH). However, factors unique to ordered systems are often responsible for unusual hardening effects. Binary compounds with identical crystal structures can exhibit significantly different hardness behavior. Ternary solute additions to ordered compounds can give rise to apparent solid solution softening as well as unexpectedly rapid hardening. These effects arise from the interaction of multiple defect types as well as the presence of multiple sublattice sites available for solute occupation. Therefore, before the SSH behavior of ordered intermetallics can be properly studied, it is necessary to develop an understanding of the types and quantities of the point defects which are present. Three recent studies by the authors are reviewed. Much of the work was done on NiAl and FeAl in binary form as well as with ternary additions. Defect concentrations over wide ranges in alloy composition and quenching temperature were determined using the ALCHEMI (atom location by channeling enhanced microanalysis) technique combined with vacancy measurements. Hardness values were also measured. It was found that most of the observed SSH effects could be rationalized on the basis of the measured point defect concentrations.

Energy dispersive x-ray (EDX) spectrum imaging has been performed in a scanning electron microscope (SEM) on a metal/ceramic braze to characterize the elemental distribution near the interface. Statistical methods were utilized to extract the relevant information (i.e., chemical phases and their distributions) from the spectrum image data set in a robust and unbiased way. The raw spectrum image was over 15 Mbytes (7500 spectra) while the statistical analysis resulted in five spectra and five images which describe the phases resolved above the noise level and their distribution in the microstructure

Site occupancies in three C15-structured AB2(X) Laves phases have been determined with Atom Location by CHanneling Enhanced MIcroanalysis (ALCHEMI). In NbCr2(V), the results are consistent with exclusive site occupancies of Nb for the A sublattice and Cr and V for the A sublattice. The B-site occupancy of V can be interpreted in terms of electronic structure. In NbCr2(Ti), the results are consistent with Ti partitioning mostly to the A sites with some anti-site defects likely. In HfV2(Nb), the results are consistent with Nb partitioning between the A and A sites. The results of the ALCHEMI analyses of these ternary C15 Laves phase materials are discussed with respect to previously determined phase diagrams and first-principles total energy and electronic structure calculations.

Changes in the electron energy-loss near-edge fine structure (ELNES) of the O-K and Co-L edges have been characterized in cobalt oxide in the vicinity of a boundary between periclase-(CoO) and spinel- (Co3O4) structured phases. The data were acquired with a conventional transmission electron microscope (CTEM) equipped with an imaging filter and operated in spectrum-line mode. Independent spectral features were identified by multivariate statistical analysis (MSA) of the raw data. The MSA of the spectrum-image acquired at the Co-L edge indicated a transition over ∼12 nm in the spectral features at the phase boundary. The variation of the ELNES at the O-K edge varied appreciably only in the interface region, whereas that at the Co-L edge also indicated subtle gradients in both phases adjacent to the interface area. These gradients are consistent with a change in the average oxidation state of the cobalt cations in the vicinity of the interface. A second independent component of the ELNES was also identified at the Co-L edge. Possible interpretations of this second component are discussed.

The site-distributions of Fe in four B2-ordered NiAl-based alloys with Fe concentrations of 10%, 2%, and 0.5% have been determined by ALCHEMI (atom-location by channeling-enhanced microanalysis). Site-distributions have been extracted with standard errors between ∼1.5% (10% Fe concentration) and ∼6% (0.5% Fe concentration). The results show that Fe has no strong site-preference in NiAl and tends to reside on the site of the stoichiometrically deficient host element.An improved ALCHEMI analysis procedure is outlined. The analysis explicidy addresses the phenomenon of ionization delocalization, which previously complicated the determination of site-distributions in aluminide intermetallics, leading to inaccurate and oftentimes nonphysical results. The improved ALCHEMI analysis also addresses the presence of anti-site defects. The data acquisition conditions have been optimized to minimize the sources of statistical and systematic error. This optimized procedure should be suitable for all analyses of B2-ordered alloys. Several analyses at different channeling orientations show that the extracted site-occupancies are robust as long as the data are acquired at orientations that are remote from any major pole of the crystal.

The width of the single-phase stability field of nickel titanate spinel (Ni2(1+x)Ti1−xO4) has been determined in order to resolve an ambiguity in the analysis of the microstructure of equilibrated and quenched spinel-containing specimens. Bulk polycrystalline diffusion couples of the constituent oxides, NiO and NiTiO3, have been prepared at several reaction temperatures between 1400°C and 1550°C. The microstructure of the reaction layers of slow-cooled specimens has been examined by SEM and the composition has been mapped using x-ray microanalysis. It is concluded that the nickel titanate spinel phase has a narrow range of stability, and that the stoichiometry of the spinel is temperature dependent. The microstructure of equilibrated and quenched specimens is discussed in light of these findings.