The High-Pressure Structural Evolution of Olivine along the Forsterite–Fayalite Join

Structural refinements from single-crystal X-ray diffraction data are reported for olivine with a composition of Fo100 (forsterite Mg2SiO4, synthetic), Fo80 and Fo62 (~Mg1.6Fe0.4SiO4 and ~Mg1.24Fe0.76SiO4, both natural) at room temperature and high pressure to ~8 GPa. The new results, along with data from the literature on Fo0 (fayalite Fe2SiO4), were used to investigate the previously reported structural mechanisms which caused small variations of olivine bulk modulus with increasing Fe content. For all the investigated compositions, the M2 crystallographic site, with its bonding configuration and its larger polyhedral volume, was observed to control the compression mechanisms in olivine. From Fo100 to Fo0, the compression rates for M2\u2013O and M1\u2013O bond lengths were observed to control the relative polyhedral volumes, resulting in a less-compressible M1O6 polyhedral volume, likely causing the slight increase in bulk modulus with increasing Fe content

Forming and preserving aragonite in shear zones: First report of blueschist facies metamorphism in the Jabal Akhdar Dome, Oman Mountains

We report the first occurrence of high-pressure metamorphic aragonite in Precambrian carbonates of the Jabal Akhdar Dome in the Oman Mountains (northern Oman). We propose a model for both its formation at blueschist facies conditions and its subsequent preservation to the surface within the tectonic framework of the Late Cretaceous obduction of the Semail Ophiolite. Aragonite formed at temperature ∼350 °C and pressure ≥0.9 GPa and is preserved within mylonitic shear zones and in stretched-fiber dilational veins where the necessary conditions for its formation and preservation, such as plastic strain accommodation, fluid-enhanced mineralogical reactions, and an anisotropic permeability structure, were preferentially met with respect to the surrounding rock. High-strain structural domains are ideal sites to look for and study prograde and retrograde high-pressure metamorphic histories in deeply subducted and exhumed terrains

Tackling a capacity bottleneck to permit large-scale downstream processing of an adenovirus-vectored vaccine

We recently described the strategy by which the University of Oxford and AstraZeneca collaboratively scaled up production of our adenovirus-vectored COVID-19 vaccine, using a productive fed batch process and distributed manufacturing approach in twelve countries around the world. Here we will focus on the development of the downstream process used to make this vaccine. In early development, the first tangential flow filtration step in our previously developed process was noted to be a potential obstacle for scale-up beyond 200L. By removing this first tangential flow filtration step, we established a simple purification process capable of handling the increasing quantities and concentrations of viral titers which are becoming a bottleneck for many adenoviral vector manufacturing processes. Product quality was in line with regulatory expectations. This strategy has enabled 2 billion doses of the Oxford/AstraZeneca vaccine to be produced by November 2021, with the majority made and used in low- and middle-income countries

Water incorporation in synthetic and natural MgAl2O4 spinel

The solubility and incorporation mechanisms of water in synthetic and natural MgAl2O4 spinel have been investigated in a series of high-pressure/temperature annealing experiments. In contrast to most other nominally anhydrous minerals, natural spinel appears to be completely anhydrous. On the other hand, non-stoichiometric Al-rich synthetic (defect) spinel can accommodate several hundred ppm water in the form of structurally-incorporated hydrogen. Infrared (IR) spectra of hydrated defect spinel contain one main O-H stretching band at 3343-3352 cm-1 and a doublet consisting of two distinct O-H bands at 3505-3517 cm-1 and 3557-3566 cm-1. IR spectra and structural refinements based on single-crystal X-ray data are consistent with hydrogen incorporation in defect spinel onto both octahedral and tetrahedral O-O edges. Fine structure of O-H bands in IR spectra can be explained by partial coupling of interstitial hydrogen with cation vacancies, or by the effects of Mg-Al disorder on the tetrahedral site. The concentration of cation vacancies in defect spinel is a major control on hydrogen affinity. The commercial availability of large single crystals of defect spinel coupled with high water solubility and similarities in water incorporation mechanisms between hydrous defect spinel and hydrous ringwoodite (Mg2SiO4) suggests that synthetic defect spinel may be a useful low-pressure analogue material for investigating the causes and consequences of water incorporation in the lower part of Earth's mantle transition zone

Accelerating and intensifying manufacturing to enable large-scale supply of a new adenovirus-vectored vaccine within 100 days

The Coalition for Epidemic Preparedness Innovations’ ‘100-day mission’ aspires to launch of a new vaccine within 100 days of pathogen identification. We have previously reported a simple fed batch process and strategy of internationally-distributed manufacturing, which enabled 2 billion doses of the ‘Oxford / AstraZeneca’ adenovirus-vectored COVID-19 vaccine to be produced in less than 600 days from publication of the SARS-CoV-2 genome sequence. The majority was made and used in low and middle income countries. Here, after briefly reviewing that previous work, we will describe efforts to further improve adenovirus manufacturing for response to future pathogen outbreaks and variants. Please click Download on the upper right corner to see the full abstract. Please click Additional File below for the presentation

Trans-oral robotic surgery for the management of oropharyngeal carcinomas: A 9-year institutional experience

Trans-oral robotic surgery (TORS) has changed surgical management of patients with oropharyngeal squamous cell carcinomas (OPSCC). In this study we present surgical and oncologic outcomes of patients with oropharyngeal squamous cell carcinomas, treated using TORS, with and without an adjuvant therapy. Sixty patients with oropharyngeal squamous cell carcinomas treated with TORS between January 2008 and December 2017 have been retrospectively evaluated considering clinicopathologic features, disease characteristics, adjuvant treatments and oncological outcomes. TORS was performed for OPSCC to the base of tongue in 41.7%, tonsils in 46.7%, soft palate and posterior pharyngeal wall in 3.3% and 5%, respectively. Neck dissection was performed in 43.3% of patients. Management strategies included surgery alone in 30%, TORS and adjuvant radiotherapy in 33.3%, and TORS plus adjuvant chemotherapy in 36.7%. The 5-year overall survival of the total group was 77.6%, the 5-year disease-free survival rate was 85.2%, and the 5-year local recurrence-free survival rate was 90.6%. Finally, in selected patients TORS appears to yield similar oncologic outcomes and functional outcomes to traditional techniques and non-operative treatment with a possible benefit on long-term quality of life. The future offers exciting opportunities to combine TORS and radiotherapy in unique ways. However, further research is urgently needed to clarify the indications for adjuvant therapy following TORS resections

Tetragonal Almandine-Pyrope Phase, TAPP:Finally a name for it, the new mineral jeffbenite

Jeffbenite, ideally Mg3Al2Si3O8, previously known as tetragonal-almandine-pyrope-phase ('TAPP'), has been characterized as a new mineral from an inclusion in an alluvial diamond from São Luiz river, Juina district of Mato Grosso, Brazil. Its density is 3.576 g/cm³ and its microhardness is ∼7. Jeffbenite is uniaxial (–) with refractive indexes ω = 1.733(5) and ε = 1.721(5). The crystals are in general transparent emerald green.This research was supported by the ERC Starting Grant 2012 to FN (agreement no. 307322) and NERC grant NE/J008583/1 to MJW and SCK. We are grateful to Chris Smith and Galina Bulanova for access to the Collier-4 diamond RC2-7

Sublithospheric diamond ages and the supercontinent cycle.

Subduction related to the ancient supercontinent cycle is poorly constrained by mantle samples. Sublithospheric diamond crystallization records the release of melts from subducting oceanic lithosphere at 300-700 km depths1,2 and is especially suited to tracking the timing and effects of deep mantle processes on supercontinents. Here we show that four isotope systems (Rb-Sr, Sm-Nd, U-Pb and Re-Os) applied to Fe-sulfide and CaSiO3 inclusions within 13 sublithospheric diamonds from Juína (Brazil) and Kankan (Guinea) give broadly overlapping crystallization ages from around 450 to 650 million years ago. The intracratonic location of the diamond deposits on Gondwana and the ages, initial isotopic ratios, and trace element content of the inclusions indicate formation from a peri-Gondwanan subduction system. Preservation of these Neoproterozoic-Palaeozoic sublithospheric diamonds beneath Gondwana until its Cretaceous breakup, coupled with majorite geobarometry3,4, suggests that they accreted to and were retained in the lithospheric keel for more than 300 Myr during supercontinent migration. We propose that this process of lithosphere growth-with diamonds attached to the supercontinent keel by the diapiric uprise of depleted buoyant material and pieces of slab crust-could have enhanced supercontinent stability