Applicability of neural networks in the estimation of brain iron content in the diagnosis of amyotrophic lateral sclerosis

Artificial Neural Networks, or simply ANN, are mathematical/computational model that are inspired by structure and functional aspects of biological neural networks. ANN, like man, learns by example. In the process of network training, network is supplied with set of data which represents examples of network’s proper behaviour. In the research we have done, neural network is created with the task to estimate the iron content in the brain of the Amyotrophic Lateral Sclerosis (ALS) patients. Network is created and trained using Neural Pattern Recognition Tool within the software package Matlab v7.10.0.499 (R2010a). Network is trained with set of data obtained from group of 50 ALS patients. Training set contains: (i) MRI signal of brain iron, (ii) EPR signal of hydroxyl radical from cerebrospinal fluid and (iii) score on ALS Functional Rating Scale (ALSFRS) for each patient individually. The results indicate that neural networks can be successfully used to predict the high content of iron in the brain, which in the perspective opens up the possibility of using this computer model as a standard tool in the diagnosis of ALS

Electrochemical oxidation of maricite NaFePO4 in mild aqueous solutions as a way to boost its charge storage capacity

Lithium has a low abundance in the Earth's crust, which in a few years will lead to difficult lithium production, and therefore difficult production of lithium-ion batteries. Sodium-ion batteries, on the other hand, have been proven to be a good replacement. The material obtained from iron combined with the phosphate and pyrophosphate compounds of sodium has attracted attention as a possible cathode material for sodium-ion batteries. NaFePO4 exists in two polymorphic structures (triphylite and maricite). Maricite NaFePO4 is a more thermodynamically stable structure than triphylite NaFePO4 but doesn’t have channels for Na+ movement and electrochemical performance of this structure is low. In comparison to maricite NaFePO4, triphylite NaFePO4 (structural analogue to LiFePO4) has one-dimensional channels for Na+-ions movement and better electrochemical activity but it is not stable and is difficult to synthesize. Herein, the maricite NaFePO4 can be obtained by sintering a polyanionic compound, Na4Fe3(PO4)2P2O7, at temperatures above 600 °C, as shown by XRD. Na4Fe3(PO4)2P2O7 is synthesized by the glycine-nitrate process after which it was sintered at temperatures above 500 °C. The glycine-nitrate process was found to catalyze the decomposition of the sintered Na4Fe3(PO4)2P2O7 to the NaFePO4 maricite. The electrochemical characterization of the sintered material, evaluated in aqueous NaNO3 and LiNO3 electrolyte by cyclic voltammetry, showed poor electrochemical activity of maricite NaFePO4. By exposing the sintered material to high anodic potentials, the electrochemical activity and specific capacity of the material were increased by 50% in case of NaNO3 and 80% in case of LiNO3 relative to the pristine with low activity. After electrochemical measurements, residual powder was characterized by FTIR and Raman spectroscopy. It was shown that high anodic polarization of the material tested in LiNO3 causes the formation of triphylite LiFePO4. Similarly, it is assumed that the electrochemical activity obtained by deep anodic polarization of the material in NaNO3 electrolyte originates from the formed triphylite NaFePO4. The obtained results open novel directions regarding the use of NaFePO4 in metal-ion rechargeable batteries

Structural properties and antisite defect formation in monoclinic Li2FeSiO4 – a DFT aspect

Properties of monoclinic Li2FeSiO4, which is a prominent candidate for future use as a cathode in lithium ion batteries, have been investigated by DFT+U method, using GGAPBE approximation, plane wave basis set and periodic boundary conditions. All calculations were performed in an antiferromagnetic state, which has been found to be energetically slightly more stable than ferromagnetic. Optimized lattice parameters and atomic coordinates have been compared to the literature data in order to verify the model. In addition, a particular attention was paid to the possibility of the formation of an antisite defect, which was introduced as the interchange between Fe and Li ions at both Li1 and Li2 crystallographic positions. The concentration of defect was varied from 0 to 25 molar per cent. Changes of structural, energetic, and magnetic properties of monoclinic Li2FeSiO4 upon increase of Li1-Fe and Li2-Fe antisite defect concentration have been analyzed and discussed in light of available experimental results

Synthesis and structural properties of sodium cobalt oxide

Sodium transition-metal oxides with general formula NaxTMO2 (TM = Co, Mn, Ni, etc.) have attracted a lot of interest in the battery community due to low cost of sodium in contrast to lithium. Sodium cobalt oxide is the most attractive of them for cathode application because of its conductive, thermic and magnetic characteristics. In this study, sodium cobalt oxide, NaxCoO2 , was synthesized by simple method which involves solid state reaction in air, at temperature of 900 ºC; starting materials were Na2CO3 and Co3O4 in stoichiometric amounts. Additionally, fluorination of the synthesized sodium cobalt oxide was carried out in vacuum at 200ºC; NH4HF2 was used as a fluorine source. Then, structural and microstructural properties of the obtained powders were examined

Fluorination of sodium cobalt oxide: effects on structure and electrochemical performance

Within this research the possibility of fluorine doping of the P2 type NaxCo02 powder was examined. As fluorine substitution already proved successful in improving cathode performance of layered lithium-based counterparts, the effects of fluorination on structure and electrochenlical properties ofP2 NaxCo02 were investigated and discussed

Simply Prepared Magnesium Vanadium Oxides as Cathode Materials for Rechargeable Aqueous Magnesium Ion Batteries

Vanadium-oxide-based materials exist with various vanadium oxidation states having rich chemistry and ability to form layered structures. These properties make them suitable for different applications, including energy conversion and storage. Magnesium vanadium oxide materials obtained using simple preparation route were studied as potential cathodes for rechargeable aqueous magnesium ion batteries. Structural characterization of the synthesized materials was performed using XRD and vibrational spectroscopy techniques (FTIR and Raman spectroscopy). Electrochemical behavior of the materials, observed by cyclic voltammetry, was further explained by BVS calculations. Sluggish Mg2+ ion kinetics in MgV2O6 was shown as a result of poor electronic and ionic wiring. Complex redox behavior of the studied materials is dependent on phase composition and metal ion inserted/deinserted into/from the material. Among the studied magnesium vanadium oxides, the multiphase oxide systems exhibited better Mg2+ insertion/deinsertion performances than the single-phase ones. Carbon addition was found to be an effective dual strategy for enhancing the charge storage behavior of MgV2O6. © 2022 by the authors

Physicochemical and electrochemical characterization of carbon derived from Al- based metal organic framework

Carbon materials derived from metal organic frameworks (MOF) have shown promising applications including energy storage and conversion, adsorption, gas storage and separation, catalysis, chemical sensing, and solid phase extraction. Here we present carbon materials derived from Al-based MOFs for use as electrodes in multivalent ion supercapacitors. Al MOFs were synthesized through complexation of fumaric acid with aluminum salts. Carbonization process of Al MOFs was followed by removal of Al2O3 via dissolving in NaOH solution. The properties of carbon materials were examined by X-ray diffraction (XRD), Thermogravimetric and Differential thermal analysis (TG/DTA), Fourier Infrared (FTIR) and Raman Spectroscopy, Particle Size Analysis (PSA), Scanning Electron Microscopy (SEM). The charge storage ability of carbon materials were examined in acidic and neutral aqueous solution using Cyclic Voltammetry at scan rates ranging from 5-500 mVs-1

Synthesis of cathode composite powders from methylcellulose matrix: Li2FeSiO4/C, Li2FeP2O7/C and LiFePO4/C

Since Padhi et al. reported the electrochemical properties of LiFePO4 in 1997 [1], polyanion cathode materials for lithium-ion batteries attract interest of researchers because of the added safety and higher voltage values in comparison to the oxide analogues with the same M2+/3+ redox pair. The higher safety and higher voltage come from strong covalent bonding within the polyanion units and, over the years, these inherent characteristics have promoted the investigation of different polyanion compounds. Among them, lithium transition-metal silicates, Li2MSiO4, and pyrophosphates, Li2MP2O7, additionally offer the possibility of extraction/ insertion two lithium ions per formula unit thus increasing theoretical capacity. However, unlike their oxide counterparts, polyanion cathodes suffer considerably from low conductivity (both ionic and electronic) which significantly limits their rate performance and therefore application in high power devices. To overcome this obstacle various strategies were developed like minimization of particle size, addition of conductive additives and/or ion doping. In this study, the approach that was used includes preparation of Li2FeSiO4/C, LiFePO4/C a nd L i2FeP2O7/C composites where carbon is obtained by pyrolytical degradation of methylcellulose and in situ during formation of polyanion active material on high temperatures. Methylcellulose, or methyl cellulose ether, is a water-soluble derivative of cellulose with an ability to gel upon heating and reversibly liquefy upon cooling due to the hydrophobic interaction between molecules containing methoxyl groups [2]. Thanks to this outstanding ability, the methylcellulose acts not only as a carbon source, but also as a dispersing agent that enables both the homogeneous deployment of the precursor compounds and the control of active material’ particle growth from the earliest stages of crystallization. This further allowed a significant shortening of high temperature treatment (to several minutes long) with additional decreases of particle agglomeration. Being both simple and inexpensive, the described method is also beneficial for commercial purposes. The electrochemical and microstructural properties of the obtained powders were examined and compared. Also, the opportunity is taken to discuss potential of a redox couple Fe2+/Fe3+ (Figure 1) in a relation to the crystal structure of a given polyanion cathode

Vanadyl phosphate as a host material for aluminium intercalation

The development of safe, durable, cheap, and environmentally friendly batteries is one of the most important challenges of modern electrochemistry. Hence, there is an interest in the investigation of aqueous batteries with multivalent ions such as calcium, magnesium, or aluminium. Furthermore, the use of polyanionic compounds as cathode material can provide multi-electron transport. VOPO4·2H2O with its layered structure is a particularly interesting and promising material. The current study is focused on the investigation of VOPO4·2H2O as cathode material in aluminium aqueous rechargeable cells. According to the literature data, the conventional reflux method is mostly used for the material’s synthesis [1]. Here is presented a sonochemical synthesis as a less time- and energy-consuming method, that starts from the mixture of vanadium(V)-oxide, phosphoric acid and water as a reaction media. The synthesis is done within 20 min. The characterization of the synthesized material includes X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and cyclovoltammetry (CV). XRD data were used for both the powders’ phase identification and crystal structure refinement. The structure of the powder was refined in the tetragonal space group P4/nmmZ (No. 129). Crystal structure refinement was based on the Rietveld full profile method [2]. The structure is characterized by infinite layers of PO4 tetrahedra linked to VO6 octahedra by shared oxygen atoms that form 2D sheets in the ab-planes; water molecules are located in the interlayer space. The refined cell parameters, a = b = 6.2136 Å, c = 7.4141 Å, are in good agreement with the literature data. Lattice parameter c is a measure of the interlayer distance, thus varies with water content. The value of the refined c parameter implies that the structure consists two water molecules per formula unit. The working electrode is prepared from a slurry of sonochemically derived VOPO4·2H2O as an active material, carbon black, and a binder dispersed in a solvent. Two different binders are used: polyvinylidene fluoride (PVDF), 2.4 wt% solution in N-methyl-2-pyrrolidone or Nafion, 5 wt% solution in a mixture of lower aliphatic alcohols and water. Cyclic voltammetry measurements are done in several electrolytes to probe the intercalation of various cations such as magnesium, calcium, and aluminium. The best results are obtained when the electrode is cycled in 1M Al(NO3)3 aqueous solution. This probably originates in different ionic radii. During the process of electrode preparation, structural changes in the powder are noticed. The structural changes were followed step by step through the combined XRD and FTIR analysis. It turns out that the structure is prone to release water molecules even when the powder is mixed with carbon black and also with the addition of a solvent, which could lead to the formation of a bilayered vanadyl phosphate. It was shown that using different solvents has a diverse impact on the structure, and consequently on powders’ cyclic performances