Garnet ceramic electrolytes for next-generation lithium batteries

All-solid-state lithium batteries are of great interest scientifically as a next-generation of electrochemical energy storage devices, owing to their superior safety features and their potential to enable new chemistries to improve performance. The properties of the solid state electrolyte are integral to the overall cell capability – to date the most promising group of materials are the garnet-structured oxides, based on Li7La3Zr2O12 (LLZO), with high room temperature ionic conductivity and a wide electrochemical stability window. There are several aspects in the development of this relatively new material which are yet to be fully understood – these are the focus of this thesis. In this work, processing cubic doped LLZO as a bulk ceramic was investigated and served as a basis for understanding its stability and electrochemical performance; it was optimised to obtain highly dense microstructures under atmosphere-controlled conditions to prevent reaction with moisture. Chemical inhomogeneities in the pellets, especially at the grain boundaries, as investigated by secondary ion mass spectrometry (SIMS) and low energy ion scattering, were shown to be important in determining the transport properties of the electrolyte - in particular the propensity for dendrite formation during cell cycling. It was shown that aluminium-rich grain boundaries in aluminium-doped LLZO favour the formation of inter-granular lithium dendrites (with a 60 % lower critical current density for cell failure) over gallium-doped LLZO. The use of germanium (Ge4+) as a dopant was studied, and shown to stabilise the cubic LLZO phase through substitution of 0.10 moles of Ge at the lithium sub-lattice (at the tetrahedral 24d sites), giving conductivities of the order 10-4 S cm-1 and redox stability over a 4.5 V range with lithium electrodes. Chemical and electrochemical characterisation of the moisture reactivity of gallium-doped LLZO was also carried out, showing a chemically-altered proton-rich region extending to 1.35 micrometres following 30 minutes immersion in H2O at 100 °C and highly reactive grain boundaries. These chemical changes led to a threefold increase in the resistance of both the electrolyte and the interface with lithium electrodes. Chemical and tracer diffusivity of protons were estimated from the diffusion profiles of H+ and D+ obtained by SIMS depth-profiling. A new methodology for measuring macroscopic lithium tracer diffusion in LLZO was introduced, using SIMS depth-profiling and isotopic labelling, in which a number of experimental parameters were varied to optimise the technique. The preliminary results for lithium diffusivity in doped LLZO obtained from this method were compared with values from other methods (impedance and nuclear magnetic resonance) and used to comment on the mechanism for lithium diffusion in the materials.Open Acces

To see or not to see: a study in maritime visibility

Η Ελλάδα είναι άρρηκτα συνδεδεμένη με τη θάλασσα που την περιβάλλει και οι θαλάσσιες μετακινήσεις έπαιζαν ανέκαθεν σημαντικό ρόλο στην ιστορία της. Το ίδιο ισχύει και στην περίπτωση της Εύβοιας, καθώς η γεωγραφική της θέση εν μέσω μυριάδων θαλάσσιων διαδρομών, συνέβαλε σημαντικά στην κοινωνική και οικονομική ανάπτυξη του νησιού. Ωστόσο τα θαλάσσια ταξίδια δεν ήταν ακριβώς ένα εγχείρημα χωρίς κινδύνους. Μία από τις βασικότερες και σημαντικότερες αποφάσεις που έπρεπε να πάρει ο θαλασσοπόρος ήταν η πορεία του πλοίου. Τόσο η πλεύση κοντά στις ακτές όσο και αψήφηση των ανοιχτών θαλασσών ενέχουν τους δικούς τους κινδύνους και ο καθορισμός λανθασμένης πορείας θα μπορούσε να θέσει σε κίνδυνο τη ζωή του πληρώματος. Υπάρχουν πολλοί λόγοι να πιστεύουμε ότι η ορατότητα πρέπει να ήταν σημαντικός παράγοντας στη διαδικασία λήψης αποφάσεων, καθώς σημεία αναφοράς όπως βουνά και ακρωτήρια χρησιμοποιούνταν ως σταθερά σημεία πλοήγησης. Το ερώτημα που γεννάται είναι η απόσταση από την οποία ήταν ορατά αυτά τα εμφανή σημεία. Παραδόξως μέχρι σήμερα οι αρχαιολογικές έρευνες δεν έχουν δώσει μεγάλη προσοχή στο θέμα του οπτικού πεδίου πάνω από τη θάλασσα και οποιεσδήποτε προτάσεις σχετικά με αυτό το θέμα συνήθως βασίζονται σε ξεπερασμένα, συχνά εσφαλμένα δεδομένα. Η συνεργασία που επιδιώχτηκε με εμπειρογνώμονα της ατμοσφαιρικής οπτικής τελικά οδήγησε σε μια καλύτερη κατανόηση της ορατότητας στη θάλασσα. Στο παρόν άρθρο παρουσιάζεται η λειτουργία του μοντέλου που χρησιμοποιήθηκε καθώς και τα αποτελέσματά του τα οποία θα εφαρμοστούν σε κάποιες από τις διαδρομές που περνούν από την Εύβοια προκειμένου να εξηγήσουμε με παραδείγματα τη σημασία της ορατότητας στη θαλάσσια πλοήγηση

Joan Brugge: Running rings around cancer

Brugge has devoted her career to uncovering how perturbations in normal cellular processes give rise to cancer

Secondary School Choral Curriculum Based on the Wisconsin Comprehensive Musicianship through Performance Project

This thesis is a two-part paper dealing with the concept of comprehensive musicianship for an elective high school choral course in a small Christian school. Part I surveys relevant literature, considers the background of comprehensive musicianship and research related to it, and defines the Wisconsin Comprehensive Musicianship Project (WCMP). Part II applies the Wisconsin Comprehensive Musicianship through Performance model by outlining a curriculum for a choral music course in a small Christian secondary school

“Should parental refusals of newborn screening be accepted?”

For over four decades, knowledge that symptoms of some inherited diseases can be prevented or reduced via early detection and treatment in newborns has underpinned state-funded screening programs in most developed countries. 1 Conditions for which newborn screening is now a recognized preventative public health initiative include phenylketonuria (PKU), congenital hypothyroidism (CHT), and, more recently, cystic fibrosis (CF) and sickle cell disorder (SCD). The use of tandem mass spectrometry to detect conditions such as amino-acidopathies and fatty-acid oxidation defects is also becoming increasingly prevalent. 2 The early identification of children who are at risk for these conditions can have very positive implications. To take the most significant example, a child born with mutations that would otherwise lead to symptoms of PKU will have a vastly different kind of life if the condition is detected in early infancy rather than later. The introduction of a modified diet at this time, although cumbersome, will prevent the onset of severe mental impairment, allowing the child to lead a virtually normal life. 3 Although clinical indications are sometimes more contentious when justifying screening for other conditions, by and large newborn screening is clinically valid and carries only minimal risk. However, it is sometimes declined by parents, presenting healthcare professionals with an ethical, legal, and practical dilemma. Consider the following scenario: Emma and Tom both work as pediatricians in a large city hospital. They have recently had their third child, a daughter named Clare. During a postnatal visit to their home by a midwife, Emma indicates that she and Tom do not want Clare to have any newborn screening. Emma reports there is no family history of any of the diseases being screened for, and she feels strongly that the probability Clare will have any of the conditions is so low that it cannot justify subjecting her to an invasive test. This scenario gives rise to three issues, each addressed below. First, is Emma and Tom’s refusal of newborn screening for Clare justifiable? Second, should the law ever mandate newborn screening over parental objections? Third, howshould such refusals be managed in practice? Using the example of PKU screening, it is argued that although refusals are often difficult to defend, legal intervention is unjustified as a means of compelling parents to allow their infant to be screened. Nevertheless, the state may be justified in exercising some degree of “influence” over parental decisionmaking, via the practices of health professionals involved in newborn screening.This article was written by Dr Ainsley Newson during the time of her employment with the University of Bristol, UK (2006-2012). Self-archived in the Sydney eScholarship Repository with permission of Bristol University, Sept 2014