Microstructural evolution and characterisation of interfacial phases in Al<inf>2</inf>O<inf>3</inf>/Ag-Cu-Ti/Al<inf>2</inf>O<inf>3</inf> braze joints

Alumina ceramics with different levels of purity have been joined to themselves using an active braze alloy (ABA) Ag–35.3Cu–1.8Ti wt.% and brazing cycles that peak at temperatures between 815 °C and 875 °C for 2 to 300 min. The microstructures of the joints have been studied using scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. A limited number of joints prepared with the ABA Ag–26.7Cu–4.5Ti wt.% have also been studied. In terms of characterising the interfacial phases, efforts were made to understand the interfacial reactions, and to determine the influence of various brazing parameters, such as the peak temperature (Tp) and time at Tp (τ), on the microstructure. In addition, the extent to which impurities in the alumina affect the interfacial microstructure has been determined. Ti3Cu3O has been identified as the main product of the reactions at the ABA/alumina interfaces. At the shortest joining time used, this phase was observed in the form of a micron-size continuous layer in contact with the ABA, alongside a nanometre-size layer on the alumina that was mostly composed of γ-TiO grains. Occasionally, single grains of Ti3O2 were observed in the thin layer on alumina. In the joints prepared with Ag–35.3Cu–1.8Ti wt.%, the interfacial structure evolved considerably with joining time, eventually leading to a high degree of inhomogeneity across the length of the joint at the highest Tp. The level of purity of alumina was not found to affect the overall interfacial microstructure, which is attributed to the formation of various solid solutions. It is suggested that Ti3Cu3O forms initially on the alumina. Diffusion of Ti occurs subsequently to form titanium oxide at the Ti3Cu3O/alumina interface.The authors acknowledge the financial support for this study provided by AWE.This is the author accepted manuscript. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S1359645415003791

Interfacial reactions between sapphire and Ag-Cu-Ti-based active braze alloys

The interfacial reactions between two commercially available Ag–Cu–Ti-based active braze alloys and sapphire have been studied. In separate experiments, Ag– 35.3Cu–1.8Ti wt.% and Ag–26.7Cu–4.5Ti wt.% alloys have been sandwiched between pieces of R-plane orientated sapphire and heated in argon to temperatures between 750 and 900 °C for 1 min. The phases at the Ag–Cu– Ti/sapphire interfaces have been studied using selected area electron diffraction, energy dispersive X-ray spectroscopy and electron energy loss spectroscopy. Gradual and subtle changes at the Ag–Cu–Ti/sapphire interfaces were observed as a function of temperature, along with the formation of a transient phase that permitted wetting of the sapphire. Unequivocal evidence is shown that when the active braze alloys melt, titanium first migrates to the sapphire and reacts to dissolve up to ~33 at.% oxygen, forming a nanometre-size polycrystalline layer with a chemical composition of Ti₂O₁₋ₓ (x<<1). Ti₃Cu₃O particles subsequently nucleate behind the Ti₂O₁₋ₓ layer and grow to become a continuous micrometre-size layer, replacing the Ti₂O₁₋ₓ layer. Finally at 845 °C, a nanometre-size γ-TiO layer forms on the sapphire to leave a typical interfacial structure of Ag–Cu/Ti₃Cu₃O/γ-TiO/sapphire consistent with that seen in samples of polycrystalline alumina joined to itself with these active braze alloys. These experimental observations have been used to establish a definitive bonding mechanism for the joining of sapphire with Ag–Cu alloys activated by small amounts of titaniumWe are grateful for the financial support for this study provided by AWE.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.actamat.2015.11.01

Bird extinctions threaten to cause disproportionate reductions of functional diversity and uniqueness

1. Human activities are driving rapid defaunation of Earth's ecosystems through increasing rates of extinction. However, the ecological consequences of species loss remain unclear, in part due to the limited availability of high-resolution functional trait data. / 2. To address this, we assess how predicted extinctions will reshape avian functional diversity quantified using a multidimensional trait space, or morphospace, reflecting variation in eight key morphological traits closely linked to ecological function across 9943 (>99%) extant bird species. / 3. We show that large regions of this morphospace are represented by very few species and, thus, vulnerable to species loss. We also find evidence that species at highest risk of extinction are both larger and functionally unique in terms of ecological trait dimensions unrelated to size, such as beak shape and wing shape. / 4. Although raw patterns suggest a positive relationship between extinction risk and functional uniqueness, this is removed when accounting for phylogeny and body mass, indicating a dominant role for clade-specific factors, including the combination of larger average body size and higher extinction risk in the non-passerine clade. / 5. Regardless of how a threat is related to uniqueness, we show using simulations that the loss of currently threatened bird species would result in a greater loss of morphological diversity than expected under random extinctions. / 6. Our results suggest that ongoing declines of threatened bird species may drive a disproportionately large loss of morphological diversity, with potentially major consequences for ecosystem functioning

BMS-supertranslation charges at the critical sets of null infinity

For asymptotically flat spacetimes, a conjecture by Strominger states that asymptotic BMS-supertranslations and their associated charges at past null infinity I − can be related to those at future null infinity I + via an antipodal map at spatial infinity i0. We analyze the validity of this conjecture using Friedrich’s formulation of spatial infinity, which gives rise to a regular initial value problem for the conformal field equations at spatial infinity. A central structure in this analysis is the cylinder at spatial infinity I representing a blow-up of the standard spatial infinity point i0 to a 2-sphere. The cylinder I touches past and future null infinities I ± at the critical sets I ± . We show that for a generic class of asymptotically Euclidean and regular initial data, BMS-supertranslation charges are not well-defined at I ± unless the initial data satisfies an extra regularity condition. We also show that given initial data that satisfy the regularity condition, BMS-supertranslation charges at I ± are fully determined by the initial data and that the relation between the charges at I − and those at I + directly follows from our regularity condition

Cell cycle regulation of proliferation versus differentiation in the central nervous system

Formation of the central nervous system requires a period of extensive progenitor cell proliferation, accompanied or closely followed by differentiation; the balance between these two processes in various regions of the central nervous system gives rise to differential growth and cellular diversity. The correlation between cell cycle lengthening and differentiation has been reported across several types of cell lineage and from diverse model organisms, both in vivo and in vitro. Furthermore, different cell fates might be determined during different phases of the preceding cell cycle, indicating direct cell cycle influences on both early lineage commitment and terminal cell fate decisions. Significant advances have been made in the last decade and have revealed multi-directional interactions between the molecular machinery regulating the processes of cell proliferation and neuronal differentiation. Here, we first introduce the modes of proliferation in neural progenitor cells and summarise evidence linking cell cycle length and neuronal differentiation. Second, we describe the manner in which components of the cell cycle machinery can have additional and, sometimes, cell-cycle-independent roles in directly regulating neurogenesis. Finally, we discuss the way that differentiation factors, such as proneural bHLH proteins, can promote either progenitor maintenance or differentiation according to the cellular environment. These intricate connections contribute to precise coordination and the ultimate division versus differentiation decision

Impact of Sex Education in Kogi State, Nigeria

The focus of this study was to investigate the impact of family sex education in secondary schools on students in Kogi State, Nigeria. The descriptive survey design was used for the study. A total of 1,960 secondary school students were drawn by stratified random sampling from 40 schools within Kogi State, Nigeria. Three research questions were generated for the study. Data collected using a researchers’ structured questionnaire were subjected to statistics of frequency counts and percentage. The results revealed that students have sexual problems, misuse of sex, high teenage pregnancies and abortion and inadequate information on sex. Among the recommendations made include the provision of adequate counseling and enlightenment programmes for students, teachers and parents on the dangers of sex misuse and abuse, and the implementation of the law against sex abuse of any form, and full enforcement of the child right act of Nigeria. Keywords: Sex, education, abuse, impact, Kogi State, Nigeri

Geophysical surveys of groundwater contamination at three sanitary landfills in Essex County, Ontario.

Dept. of Geology and Geological Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1984 .A555. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.Sc.)--University of Windsor (Canada), 1984

Post-crash management of road traffic injury victims in Iran. Stakeholders' views on current barriers and potential facilitators

<p>Abstract</p> <p>Background</p> <p>Road traffic injuries are a major public health problem, especially in low- and middle-income countries. Post-crash management can play a significant role in minimizing crash consequences and saving lives. Iran has one of the highest mortality rates from road traffic injuries in the world. The present study attempts to fill the knowledge gap and explores stakeholders' perceptions of barriers to – and facilitators of – effective post-crash management in Iranian regions.</p> <p>Methods</p> <p>Thirty-six semi-structured interviews were conducted with medical services personnel, police officers, members of Red Crescent, firefighters, public-health professionals, road administrators; some road users and traffic injury victims. A qualitative approach using grounded theory method was employed to analyze the material gathered.</p> <p>Results</p> <p>The core variable was identified as "poor quality of post crash management". Barriers to effective post-crash management were identified as: involvement of laypeople; lack of coordination; inadequate pre-hospital services; shortcomings in infrastructure. Suggestions for laypeople included: 1) a public education campaign in first aid, the role of the emergency services, cooperation of the public at the crash site, and 2) target-group training for professional drivers, police officers and volunteers involved at the crash scene. An integrated trauma system and infrastructure improvement also is crucial to be considered for effective post-crash management.</p> <p>Conclusion</p> <p>To sum up, it seems that the involvement of laypeople could be a key factor in making post-crash management more effective. But system improvements are also crucial, including the integration of the trauma system and its development in terms of human resources (staffing and training) and physical resources as well as the infrastructure development.</p

An IoE Blockchain-Based Network Knowledge Management Model for Resilient Disaster Frameworks

The disaster area is a constantly changing environment, which can make it challenging to distribute supplies effectively. The lack of accurate information about the required goods and potential bottlenecks in the distribution process can be detrimental. The success of a response network is dependent on collaboration, coordination, sovereignty, and equal distribution of relief resources. To facilitate these interactions and improve knowledge of supply chain operations, a reliable and dynamic logistic system is essential. This study proposes the integration of blockchain technology, the Internet of Things (IoT), and the Internet of Everything (IoE) into the disaster management structure. The proposed disaster response model aims to reduce response times and ensure the secure and timely distribution of goods. The hyper-connected disaster supply network is modeled through a concrete implementation on the Network Simulation (NS2) platform. The simulation results demonstrate that the proposed method yields significant improvements in several key performance metrics. Specifically, it achieved more than a 30% improvement in the successful migration of tasks, a 17% reduction in errors, a 15% reduction in delays, and a 9% reduction in energy consumption

Problems persist in reporting of methods and results for the WOMAC measure in hip and knee osteoarthritis trials

Purpose The Western Ontario and McMaster Universities Arthritis Index (WOMAC) is a commonly used outcome measure for osteoarthritis. There are different versions of the WOMAC (Likert, visual analogue or numeric scales). A previous review of trials published before 2010 found poor reporting and inconsistency in how the WOMAC was used. This review explores whether these problems persist. Methods This systematic review included randomised trials of hip and/or knee osteoarthritis published in 2016 that used the WOMAC. Data were extracted on the version used, score range, analysis and results of the WOMAC, and whether these details were clearly reported. Results This review included 62 trials and 41 reported the WOMAC total score. The version used and item range for the WOMAC total score were unclear in 44% (n = 18/41) and 24% (n = 10/41) of trials, respectively. The smallest total score range was 0–10 (calculated by averaging 24 items scored 0–10); the largest was 0–2400 (calculated by summing 24 items scored 0–100). All trials reported the statistical analysis methods but only 29% reported the between-group mean difference and 95% confidence interval. Conclusion Details on the use and scoring of the WOMAC were often not reported. We recommend that trials report the version of the WOMAC and the score range used. The between-group treatment effect and corresponding confidence interval should be reported. If all the items of the WOMAC are collected, the total score and individual subscale scores should be presented. Better reporting would facilitate the interpretation, comparison and synthesis of the WOMAC score in trials