Modelling the defect processes of materials for energy applications

The technological requirement for ever more efficient materials for the energy and electronics sectors has led to the consideration of numerous compositionally and structurally complicated systems. These systems include solid solutions that are difficult to model using electronic structure calculations because of the numerous possibilities in the arrangement of atoms in supercells. The plethora of such possible arrangements leads to extensive and large numbers of potential supercells, and this renders the investigation of defect properties practically intractable. We consider recent advances in oxide interfaces where studies have demonstrated that it is feasible to tune their defect processes effectively. In this review, we aim to contribute to the ongoing discussion in the community on simple, efficient and tractable ways to realise research in solid solutions and oxide interfaces. The review considers the foundations of relevant thermodynamic models to extract point defect parameters and the special quasirandom structures method to model the supercell of solid solutions. Examples of previous work are given to highlight these methodologies. The review concludes with future directions, systems to be considered and a brief assessment of the relevant methodologies

2D−3D crossover of the in-plane paraconductivity in optimal doped ReBa₂Cu₃O₇₋δ (Re = Y, Ho) single crystals

The effect of the fluctuation paraconductivity in optimal oxygen-doped ReBa₂Cu₃O₇₋δ (Re = Y, Ho) single crystals has been investigated. The results indicate that the theoretical model of Aslamazov–Larkin (AL) describes the temperature dependence of fluctuation paraconductivity (FP) near the critical temperature (Tc). At temperatures above the temperature of the 2D−3D crossover this dependence is appropriately described by the Lawrence–Doniach (LD) theory. The extended linear dependence of ρab(Т), in the crystal with the minimum critical temperature indicates that we have a high defect concentration in this sample. This in turn causes negative processes into forming fluctuation pairs

Atomistic models for R1–xPrxBa2Cu3O7–δ (R = Y and lanthanides) and related oxides

We report the results of defect structures studies of silicon implanted at different temperatures with Mn ions (Si:Mn) and of GaMnAs layers, next annealed under ambient and high pressures. An influence of annealing conditions on structural properties of Si:Mn and GaMnAs layers was investigated. It has been confirmed that annealing of the Si:Mn samples after implantation results in crystallization of silicon inside the buried postimplanted layer, as well as in the formation of ferromagnetic Mn4Si7 precipitates. A change of strain in the GaMnAs layer, from the compressive to the tensile one, related to a creation of nanoclustered MnAs, was found to be dependent on processing conditions and primary existing structural defects, while independent of the Mn concentration. An influence of primary defects on the structural transformations of the GaMnAs layer is discussed.Атомістичні методи імітаційного моделювання, основані на принципі мінімізації енергії, використані для вивчення структурних параметрів ряду орторомбічних R1–xPrxBa2Cu3O6.5 і пов'язаних з ними сполук. Нові міжатомні потенційні параметри взаємодії одержані для широкого діапазону оксидів, таких як CuO, R2O3, RBa2Cu3O6.5 і R1–xPrxBa2Cu3O6.5 (всього 62 сполуки). Одержані дані знаходяться в доброму узгoдженні з попередніми результатами експериментальних і теоретичних досліджень. Мета даної роботи – прогнозування решіточних потенціалів взаємодії, що можуть бути надалі використані як основа для теоретичного вивчення дефектної хімії надпровідних купратів та інших технологічно важливих оксидів

Atomistic studies of Li+ migration in Y₂O₃ and the structure of related oxides

Atomistic computer simulation techniques based on energy minimization have been employed to predict the equilibrium lattice parameters and volumes of a series of rare-earth sesquioxides and their polymorphs. The results have been found in agreement with experimental data and ab initio studies given in the literature. To demonstrate the applicability of the computational methodology the migration of lithium ions (Li⁺) in yttria (Y₂O₃) has been considered.Атомістичні методи комп’ютерного моделювання, основані на принципі мінімізації енергії, використані для прогнозування рівноважних параметрів і об’єма кристалічної гратки ряда рідкоземельних оксидів та їх поліморф. Результати моделювання знаходяться в доброму узгoдженні з експериментальними і літературними даними. Для демонстрації запропонованої обчислювальної методики розглянутo міграцію іонів літія (Li⁺) в оксиді ітрія (Y₂O₃).Атомистические методы компьютерного моделирования, основанные на принципе минимизации энергии, использованы для предсказания равновесных параметров и объема кристаллической решетки ряда редкоземельных оксидов и их полиморф. Результаты моделирования находятся в хорошем согласии с экспериментальными и литературными данными. Для демонстрации применимости предложенной вычислительной методики рассмотрена миграция ионов лития (Li⁺) в оксиде иттрия (Y₂O₃)

Antibody Screening Using a Human iPSC-based Blood-Brain Barrier Model Identifies Antibodies that Accumulate in the CNS

Drug delivery across the blood-brain barrier (BBB) remains a significant obstacle for the development of neurological disease therapies. The low penetration of blood-borne therapeutics into the brain can oftentimes be attributed to the restrictive nature of the brain microvascular endothelial cells (BMECs) that comprise the BBB. One strategy beginning to be successfully leveraged is the use of endogenous receptor-mediated transcytosis (RMT) systems as a means to shuttle a targeted therapeutic into the brain. Limitations of known RMT targets and their cognate targeting reagents include brain specificity, brain uptake levels, and off-target effects, driving the search for new and potentially improved brain targeting reagent-RMT pairs. To this end, we deployed human-induced pluripotent stem cell (iPSC)-derived BMEC-like cells as a model BBB substrate on which to mine for new RMT-targeting antibody pairs. A nonimmune, human single-chain variable fragment (scFv) phage display library was screened for binding, internalization, and transcytosis across iPSC-derived BMECs. Lead candidates exhibited binding and internalization into BMECs as well as binding to both human and mouse BBB in brain tissue sections. Antibodies targeted the murine BBB after intravenous administration with one particular clone, 46.1-scFv, exhibiting a 26-fold increase in brain accumulation (8.1 nM). Moreover, clone 46.1-scFv was found to associate with postvascular, parenchymal cells, indicating its successful receptor-mediated transport across the BBB. Such a new BBB targeting ligand could enhance the transport of therapeutic molecules into the brain

Electrophysical properties of nanoporous cerium dioxide–water system

The impedance of nanoporous cerium dioxide with adsorbed water is investigated in the frequency range 103–104 Hz at temperatures near the water–ice phase transition. Here we show that the manifestation of impedance peculiarities at phase transition is caused by the dielectric constant of the matrix