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

Quantum circuits with many photons on a programmable nanophotonic chip

Growing interest in quantum computing for practical applications has led to a surge in the availability of programmable machines for executing quantum algorithms. Present day photonic quantum computers have been limited either to non-deterministic operation, low photon numbers and rates, or fixed random gate sequences. Here we introduce a full-stack hardware-software system for executing many-photon quantum circuits using integrated nanophotonics: a programmable chip, operating at room temperature and interfaced with a fully automated control system. It enables remote users to execute quantum algorithms requiring up to eight modes of strongly squeezed vacuum initialized as two-mode squeezed states in single temporal modes, a fully general and programmable four-mode interferometer, and genuine photon number-resolving readout on all outputs. Multi-photon detection events with photon numbers and rates exceeding any previous quantum optical demonstration on a programmable device are made possible by strong squeezing and high sampling rates. We verify the non-classicality of the device output, and use the platform to carry out proof-of-principle demonstrations of three quantum algorithms: Gaussian boson sampling, molecular vibronic spectra, and graph similarity

A guide to the crystallographic analysis of icosahedral viruses

Determining the structure of an icosahedral virus crystal by X-ray diffraction follows very much the same course as conventional protein crystallography. The major differences arise from the relatively large sizes of the particles, which significantly affect the data collection process, data processing and management, and later, the refinement of a model. Most of the other differences are due to the high 5 3 2 point group symmetry of icosahedral viruses. This alters dramatically the means by which initial phases are obtained by molecular substitution, extended to higher resolution by electron density averaging and density modification, and the refinement of the structure in the light of high non-crystallographic symmetry. In this review, we attempt to lead the investigator through the various steps involved in solving the structure of a virus crystal. These steps include the purification of viruses, their crystallization, the recording of X-ray diffraction data, and its reduction to structure amplitudes. It further addresses the problems attending phase determination and ultimately the refinement of a model. Finally, we describe the unique properties of virus crystals and the factors that influence their physical and diffraction properties

Multifunctional nanowires and hierarchical 3D nanostructures of material composites for energy storage

Composites of functional materials have long been synthesized for achieving enhanced physical and chemical properties. In this era of energy intensive electronics and electric vehicles, energy storage devices utilising composite materials could offer improved performance at a lower cost. Furthermore, if the composite materials are synthesized in one-dimensional morphology at a nano level, conductivity and thus electrical properties could be multiplied. A range of materials with different functionalities have been synthesized by our group recently; as a typical example synthesis of a composite nanowire containing NiO and CuO for supercapacitive energy storage is detailed in this paper and compared the performance of the composite wires with its component binary wires. The materials were synthesized by electrospinning technique and characterized for their structure, microstructure, surface properties and electrochemical properties. The results shows that a composite wire containing materials for similar electrical conductivity would lead to improved charge storage performance than their single component counterparts

Correlation study on temperature dependent conductivity and line profile along the LLTO/LFP-C cross section for all solid-state Lithium-ion batteries

Nanocrystalline lithium lanthanum titanate (LLTO) – lithium iron phosphate (LFP/C) layered pellets have been prepared to analyze its interface for all solid-state batteries. The conductivity of the samples as a function of temperatures was analyzed and reported. The total conductivity of the sample at room temperature is in the order of 10−5 S cm−1. The SEM and line scan analysis of the samples have been carried out across the cross sections at different temperatures. The study gives a correlation between the line profiles across the LLTO-LFP/C interface and the temperature dependent conductivity of the sample at various temperatures for the first time. At lower temperatures up to 398 K, a narrow interface region occurs at the LLTO – LFP/C interface. At higher temperatures, the ions of elements with higher atomic mass than the lithium, such as lanthanum, iron, titanium, are also accumulate near the interface, which have been verified from the broad interface region occurring in the elemental line scan mapping across the interface. This accumulation of ions causes an additional impediment to the movement of Li+ ions which results in the breakdown in conductivity at 448 K