Giant thermal hysteresis in Verwey transition of single domain Fe3O4 nanoparticles

Most interesting phenomena of condensed matter physics originate from interactions among different degrees of freedom, making it a very intriguing yet challenging question how certain ground states emerge from only a limited number of atoms in assembly. This is especially the case for strongly correlated electron systems with overwhelming complexity. The Verwey transition of Fe3O4 is a classic example of this category, of which the origin is still elusive 80 years after the first report. Here we report, for the first time, that the Verwey transition of Fe3O4 nanoparticles exhibits size-dependent thermal hysteresis in magnetization, 57Fe NMR, and XRD measurements. The hysteresis width passes a maximum of 11 K when the size is 120 nm while dropping to only 1 K for the bulk sample. This behavior is very similar to that of magnetic coercivity and the critical sizes of the hysteresis and the magnetic single domain are identical. We interpret it as a manifestation of charge ordering and spin ordering correlation in a single domain. This work paves a new way of undertaking researches in the vibrant field of strongly correlated electron physics combined with nanoscience.Comment: 13 pages, 4 figure

Neuropathological changes in dorsal root ganglia induced by pyridoxine in dogs

Pyridoxine (PDX; vitamin B6), is an essential vitamin. PDX deficiency induces various symptoms, and when PDX is misused it acts as a neurotoxicant, inducing severe sensory neuropathy. To assess the possibility of creating a reversible sensory neuropathy model using dogs, 150 mg/kg of PDX was injected subcutaneously into dogs for 7 days and body weight measurements, postural reaction assessments, and electrophysiological recordings were obtained. In addition, the morphology of dorsal root ganglia (DRG) and changes in glial fibrillary acidic protein (GFAP) immunoreactive satellite glial cells and ionized calcium-binding adapter molecule 1 (Iba-1) immunoreactive microglia/macrophages were assessed at 1 day, 1 week, and 4 weeks after the last PDX treatment. During the administration period, body weight and proprioceptive losses occurred. One day after the last PDX treatment, electrophysiological recordings showed the absence of the H-reflex in the treated dogs. These phenomena persisted over the four post-treatment weeks, with the exception of body weight which recovered to the pre-treatment level. Staining (CV and HE) results revealed significant losses of large-sized neurons in the DRG at 1 day and 1 week after PDX treatment cessation, but the losses were recovered at 4 weeks post-treatment. The Iba-1 and GFAP immunohistochemistry results showed pronounced increases in reactive microglia/macrophage and satellite glial cell at 1 day and 1 week, respectively, after the last PDX treatment, and thereafter, immunoreactivity decreased with increasing time after PDX treatment. The results suggest that PDX-induced neuropathy is reversible in dogs; thus, dogs can be considered a good experimental model for research on neuropathy.This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Sci‑ ence, ICT & Future Planning (NRF-2017R1A1A1A05000762). The funding body played no role in the design and interpretation of the experiments. The found‑ ing sponsors had no role in the study design, performance, data collection and analysis, decision to publish, or preparation/writing of the manuscript

Biochar-based adsorbents for carbon dioxide capture: a critical review

Carbon dioxide (CO2) is the main anthropogenic greenhouse gas contributing to global warming, causing tremendous impacts on the global ecosystem. Fossil fuel combustion is the main anthropogenic source of CO2 emissions. Biochar, a porous carbonaceous material produced through the thermochemical conversion of organic materials in oxygen-depleted conditions, is emerging as a cost-effective green sorbent to maintain environmental quality by capturing CO2. Currently, the modification of biochar using different physico-chemical processes, as well as the synthesis of biochar composites to enhance the contaminant sorption capacity, has drawn significant interest from the scientific community, which could also be used for capturing CO2. This review summarizes and evaluates the potential of using pristine and engineered biochar as CO2 capturing media, as well as the factors influencing the CO2 adsorption capacity of biochar and issues related to the synthesis of biochar-based CO2 adsorbents. The CO2 adsorption capacity of biochar is greatly governed by physico-chemical properties of biochar such as specific surface area, microporosity, aromaticity, hydrophobicity and the presence of basic functional groups which are influenced by feedstock type and production conditions of biochar. Micropore area (R2 = 0.9032, n = 32) and micropore volume (R2 = 0.8793, n = 32) showed a significant positive relationship with CO2 adsorption capacity of biochar. These properties of biochar are closely related to the type of feedstock and the thermochemical conditions of biochar production. Engineered biochar significantly increases CO2 adsorption capacity of pristine biochar due to modification of surface properties. Despite the progress in biochar development, further studies should be conducted to develop cost-effective, sustainable biochar-based composites for use in large-scale CO2 capture

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Eurhadina Haupt 1929

Genus Eurhadina Haupt, 1929 Eurhadina Haupt, 1929: 1075 (Type species: Cicada pulchella Fallén, 1806) Diagnosis. Face anterior part swollen in lateral view. Body depressed and robust. Forewing narrow and usually with one dark brown spot on M 1 + 2 vein. Hind wing submarginal vein absent at apex and with vannal vein. Subgenital plate nearly straight and slightly curved, with one macroseta near basal margin and several microsetae at apex. Apex of style simply pointed and bent, without tooth on inner side. Aedeagus strongly recurved in lateral view, with two pairs of branches at apex.Published as part of Oh, Sumin, Lim, Jongok & Jung, Sunghoon, 2016, A new species of the genus Eurhadina Haupt (Hemiptera: Auchenorrhyncha: Cicadellidae: Typhlocybinae) from Korea, with a key to Korean species in Zootaxa 4103 (1), DOI: 10.11646/zootaxa.4103.1.7, http://zenodo.org/record/26250

Eurhadina

Key to the Eurhadina species of the Korean Peninsula 1. Aedeagus with apical processes branched......................................................................................................................................... 2 Aedeagus with apical processes unbranched..................................................................................................................................... 4 2. Aedeagus with preapical process branched....................................................................................................................................... 3 Aedeagus with preapical process unbranched................................................................................ E. (E.) betularia Anufriev, 1969 3. Aedeagus with branch of preapical process originating at same point as branch of inner process..................................................... .................................................................................................................................................. E. (E.) wagneri Dworakowska, 1969 Aedeagus with branch of preapical process originating at ending point of apical process.............. E. (E.) pulchella (Fallen, 1806) 4. Aedeagus preapical process with 2 branches........................................................................... E. (E.) koreana Dworakowska, 1971 Aedeagus preapical process with 3 branches (Fig. 5) .......................................................................... E. (E.) dongwolensis sp. nov.Published as part of Oh, Sumin, Lim, Jongok & Jung, Sunghoon, 2016, A new species of the genus Eurhadina Haupt (Hemiptera: Auchenorrhyncha: Cicadellidae: Typhlocybinae) from Korea, with a key to Korean species in Zootaxa 4103 (1), DOI: 10.11646/zootaxa.4103.1.7, http://zenodo.org/record/26250