Synthesis and characterization of LNMO cathode materials for lithium-ion batteries

Abstract Synthesis of LiNi0.5Mn1.5O4 (LNMO), a promising cathode material for next generation lithium-ion batteries, was performed via Liquid Phase Self-propagating High-temperature Synthesis (LPSHS) and Aerosol Spray Pyrolysis (ASP) techniques. In the case of the LPSHS technique, the effect of the "fuel" quantity of the precursor solution on the structure, morphology and electrochemical performance of the materials was studied, while in the case of the ASP technique the effect of eight different calcination profiles on the structure, morphology, crystalline phase and electrochemical performance of the material. Structural characterization was performed through XRD, SEM, TEM, BET and Raman spectroscopy, while the electrochemical activity was evaluated via charge/discharge galvanostatic characterization. The results showed that the optimal LPSHS material was obtained for a molar ratio of metal ions/fuel = 3:1 exhibiting stable specific capacity over the cycles even by increasing the C-rate. Τhe optimal ASP material was identified in the case of calcination at 850°C. Both materials had the disordered Fd-3m structure of the LNMO spine

Nuclear inclusions of pathogenic ataxin-1 induce oxidative stress and perturb the protein synthesis machinery

Spinocerebellar ataxia type-1 (SCA1) is caused by an abnormally expanded polyglutamine (polyQ) tract in ataxin-1. These expansions are responsible for protein misfolding and self-assembly into intranuclear inclusion bodies (IIBs) that are somehow linked to neuronal death. However, owing to lack of a suitable cellular model, the downstream consequences of IIB formation are yet to be resolved. Here, we describe a nuclear protein aggregation model of pathogenic human ataxin-1 and characterize IIB effects. Using an inducible Sleeping Beauty transposon system, we overexpressed the ATXN1(Q82) gene in human mesenchymal stem cells that are resistant to the early cytotoxic effects caused by the expression of the mutant protein. We characterized the structure and the protein composition of insoluble polyQ IIBs which gradually occupy the nuclei and are responsible for the generation of reactive oxygen species. In response to their formation, our transcriptome analysis reveals a cerebellum-specific perturbed protein interaction network, primarily affecting protein synthesis. We propose that insoluble polyQ IIBs cause oxidative and nucleolar stress and affect the assembly of the ribosome by capturing or down-regulating essential components. The inducible cell system can be utilized to decipher the cellular consequences of polyQ protein aggregation. Our strategy provides a broadly applicable methodology for studying polyQ diseases

Clustering Properties of Merger Waves: Space, Time or Industry?

We study the degree of agglomeration of acquisition activity within clusters of temporal, geographic and industrial proximity based on almost 600,000 individual transactions. The findings indicate that significant clustering occurs in time and across industries, while the results on geographic clustering are mixed. This supports the view that merger waves are mostly driven by neoclassical motives

New product introduction : follower firm timing behaviour

A multidisciplinary perspective is taken to the analysis of data upon the follower firm timing behaviour of 99 “non-pioneering” firms introducing low fat products into U.S. food markets, encompassing extant approaches in marketing, economic and managerial literatures. The payoffs to followers are considered to be related to demand growth, the extent of competition, early mover advantages, firm characteristics, and risk and entry cost reductions. The propensity of firms to react to these potential payoffs is considered as involving four sequential stages and determined by organisational characteristics. The findings suggest: (i) follower firms vary in the rate at which they ultimately move through each and all of the stages identified; (ii) there is evidence that firm characteristics, time and previous entry (although not simply) impact upon the speed of market entry by firms reflecting the various influences on payoffs identified; and (iii) speeds of reaction are related to firms’ abilities to internalize external market developments

Assessing the axonal translocation of CeO2 and SiO2 nanoparticles in the sciatic nerve fibers of the frog: an ex vivo electrophysiological study

Georgia Kastrinaki,1,* Christos Samsouris,2,* Efstratios K Kosmidis,3 Eleni Papaioannou,1 Athanasios G Konstandopoulos,1,4 George Theophilidis2 1Aerosol and Particle Technology Laboratory (APTL), CERTH/CPERI, Thessaloniki, Greece; 2Laboratory of Animal Physiology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece; 3Laboratory of Physiology, Department of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece; 4Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece *These authors contributed equally to this work Abstract: The axonal translocation of two commonly used nanoparticles in medicine, namely CeO2 and SiO2, is investigated. The study was conducted on frog sciatic nerve fibers in an ex vivo preparation. Nanoparticles were applied at the proximal end of the excised nerve. A nerve stimulation protocol was followed for over 35 hours. Nerve vitality curve comparison between control and exposed nerves showed that CeO2 has no neurotoxic effect at the concentrations tested. After exposure, specimens were fixed and then screen scanned every 1 mm along their length for nanoparticle presence by means of Fourier transform infrared microscopy. We demonstrated that both nanoparticles translocate within the nerve by formation of narrow bands in the Fourier transform infrared spectrum. For the CeO2, we also demonstrated that the translocation depends on both axonal integrity and electrical activity. The speed of translocation for the two species was estimated in the range of 0.45–0.58 mm/h, close to slow axonal transportation rate. Transmission electron microscopy provided direct evidence for the presence of SiO2 in the treated nerves. Keywords: CeO2, SiO2, FTIR, nanoparticles, ex vivo electrophysiology, frog sciatic nerve, translocatio

SnO2 anode materials for high capacity Li-ion cells

Tin-based materials, especially tin oxide, have been widely investigated as potential graphite substitutes anodes"br" of Li-ion batteries. In comparison to graphite anode, the SnO2 anodes shows high theoretical capacity of 1494"br" mAhg-1 in a voltage range of 0-2 V, furthermore it is also inexpensive, exhibits low toxicity and is"br" environmentally friendly. Unfortunately, during the lithiation process (i.e. conversion and alloying reaction), tin"br" dioxide suffers of a drastic volumetric expansion, that induces surface cracking accompanied by an electrical"br" contact loss with the current collector and subsequent capacity fading. It’s well known that reducing the particle"br" size of SnO2, the surface will be increased and consequently the volume expansion during lithium"br" insertion/extraction will be reduced. For these reasons, we synthesized SnO2 particles by an aerosol method and"br" we compare the results with commercial SnO2 particles and their mixtures with different carbon sources."br" All the materials were morphological and electrochemical characterized in order to investigate the influence of"br" crystal structure, particle size, morphology and surface area on cell cyclability. Cyclic voltammetry and"br" galvanostatic discharge/charge cycling have been used to test the electrochemical behavior of SnO2 anodes