EPR study of Mn site substituted Pr based Doped Rare Earth Manganites

In this paper, we present the investigations of Electron Paramagnetic Resonance (EPR) on Mn site substituted Pr based Doped rare Earth Manganites i.e. Pr0.60Ca0.40MnO3 and Pr0.60Ca0.40Mn0.85Zn0.15O3. Changes in physical properties as lattice parameters, average valence of Mn site was observable of those manganites. X-ray diffraction pattern shows that both Pr0.60Ca0.40MnO3 and Pr0.60Ca0.40Mn0.85Zn0.15O3 have single phase and without the other secondary or impurity phase and indexed supported the Pbnm space group. The value of x in Pr0.60Ca0.40Mn1-xZnxO3 increases, the average valence V was increased except for a fixed composition, i.e. x remains unchanged, the average valence V was decreased as we go from less valency to high valency (i.e., from divalent to trivalent and from trivalent to tetravalent. The EDXS analysis of those materials shows good homogeneity, but there are experimental errors in composition. It is seen from the SEM images that is formed in different shape grains. The average grain sizes of the samples are different for Pr0.60Ca0.40MnO3 and Pr0.06Ca0.40Mn0.85Zn0.15O3 The paramagnetic resonance spectra parameters (effective g-factor, peak-to-peak line width) of Pr0.60Ca0.40MnO3 and Pr0.60Ca0.40Mn0.85Zn0.15O3.have been used to study the paramagnetic spin correlations and spin dynamics. As for Pr0.60Ca0.40MnO3 the line width becomes wider because of the contribution of small polaron jumping within the PM mechanism. However, as for Pr0.60Ca0.40Mn0.85Zn0.15O3 the broadening of EPR line-width is understood with the spin-lattice relaxation mechanism, g value decreased from 1.99 to 1.79. Therefore, the Zn dopant not solely changes the parent spin correlation in the PM regime however additionally suppresses the development of orbital ordering.

Relationships Between the Microbial Composition and the Geochemistry and Mineralogy of the Cobalt-Bearing Legacy Mine Tailings in Northeastern Ontario

Mine tailings host dynamic biogeochemical processes that can mobilize a range of elements from the host material and release them into the environment through acidic, neutral, or alkaline mine drainage. Here we use a combination of mineralogical, geochemical, and microbiological techniques that provide a better understanding of biogeochemical processes within the surficial layers of neutral cobalt and arsenic-rich tailings material at Cobalt, ON, Canada. Tailings material within 30-cm depth profiles from three tailings sites (sites A, B, and C) were characterized for their mineralogical, chemical and microbial community compositions. The tailings material at all sites contains (sulf)arsenides (safflorite, arsenopyrite), and arsenates (erythrite and annabergite). Site A contained a higher and lower amount of (sulf)arsenides and arsenates than site B, respectively. Contrary to site A and B, site C depicted a distinct zoning with (sulf)arsenides found in the deeper reduced zone, and arsenates occurring in the shallow oxidized zone. Variations in the abundance of Co+As+Sb+Zn (Co#), Fe (Fe#), total S (S#), and average valence of As indicated differences in the mineralogical composition of the tailings material. For example, material with a high Co#, lo Fe# and high average valence of As commonly have a higher proportion of secondary arsenate to primary (sulf)arsenide minerals. Microbial community profiling indicated that the Cobalt tailings are primarily composed of Actinobacteria and Proteobacteria, and known N, S, Fe, methane, and possible As-cycling bacteria. The tailings from sites B and C had a larger abundance of Fe and S-cycling bacteria (e.g., Sulfurifustis and Thiobacillus), which are more abundant at greater depths, whereas the tailings of site A had a higher proportion of potential As-cycling and -resistant genera (e.g., Methylocystis and Sphingomonas). A multi-variate statistical analysis showed that (1) distinct site-specific groupings occur for the Co # vs. Fe #, Co# vs. S#’s and for the microbial community structure and (2) microbial communities are statistically highly correlated to depth, S#, Fe#, pH and the average valence of As. The variation in As valence correlated well with the abundance of N, S, Fe, and methane-cycling bacteria. The results of this study provide insights into the complex interplay between minerals containing the critical element cobalt, arsenic, and microbial community structure in the Cobalt Mining Camp tailings.

Machine learning assisted prediction of the Young’s modulus of compositionally complex alloys

We identify compositionally complex alloys (CCAs) that offer exceptional mechanical properties for elevated temperature applications by employing machine learning (ML) in conjunction with rapid synthesis and testing of alloys for validation to accelerate alloy design. The advantages of this approach are scalability, rapidity, and reasonably accurate predictions. ML tools were implemented to predict Young’s modulus of refractory-based CCAs by employing different ML models. Our results, in conjunction with experimental validation, suggest that average valence electron concentration, the difference in atomic radius, a geometrical parameter λ and melting temperature of the alloys are the key features that determine the Young’s modulus of CCAs and refractory-based CCAs. The Gradient Boosting model provided the best predictive capabilities (mean absolute error of 6.15 GPa) among the models studied. Our approach integrates high-quality validation data from experiments, literature data for training machine-learning models, and feature selection based on physical insights. It opens a new avenue to optimize the desired materials property for different engineering applications.

An inverse-spinel Mg2MnO4 cathode for high-performance and flexible aqueous zinc-ion batteries

The inverse-spinel Mg2MnO4 has rich high-average-valence-state Mn (4.5). P-APSA hydrogel, which has high adhesion and good compatibility with the Zn anode, is used as an electrolyte to construct a flexible battery.

Modulation of emotion perception and memory via sub-threshold amygdala stimulation in humans

A common human experience is noticing that emotional life events are more vividly remembered than dull ones. Studies show that the amygdala plays a central role in such emotionally driven enhancement of memory. With this in mind, we investigated the effect of electrical brain stimulation of the left human amygdala on performance on an emotional perception and emotional memory task. We randomly applied sub-threshold 50 Hz stimulation to the left amygdala in 10 patients (5 female and 5 male) with intracranial electrodes during the encoding portion of an emotional valence perception and emotional memory task. We found that amygdala stimulation did not affect reported valence for neutral stimuli (non-stimulated group average valence 5.34, stimulated 5.38, p=0.68) but it did affect positively (non-stimulated group average valence 7.31, stimulated 6.70, p=0.004) and negatively (non-stimulated group average valence 2.79, stimulated 3.55, p=0.0002) valenced stimuli in effect reporting both valence categories as more neutral. Furthermore, we found that stimulation did not significantly disrupt memory for neutral stimuli (68% vs. 61% correctly remembered p=0.48) or positive stimuli (87% vs. 70% correct, trend towards significant difference p=0.09) but did for negative stimuli (83% vs. 67% correct, p=0.03). These results suggest that electrical brain stimulation by our parameters likely reversibly inhibits amygdala function disrupting neural networks responsible for emotional perception and memory. This effect may have clinical implications in treatment of certain neuropsychiatric disorders, such as emotional dysregulation and post-traumatic stress disorder.Statement of significanceThe current study builds and expands on extensive prior research into the function of the human amygdala. It provides the first systematic description in humans of a cognitive change brought about by direct electrical stimulation of the amygdala on perception of emotional valence and emotional memory. The results provide further evidence on the importance of the amygdala in human cognition. Likewise, out method utilized to study the function of the amygdala can be extended to study the function of other brain regions in humans, such as the cingulate. While these results are preliminary and need to be duplicated, we aim to further study the effects of amygdala stimulation on emotional processing including possible therapeutic application for diverse group of neuropsychiatric conditions.

The relationships between exercise and affective states: a naturalistic, longitudinal study of recreational runners

Background Although people generally feel more positive and more energetic in the aftermath of exercise than before, longitudinal research on how exercise relates to within-person fluctuations in affect over the course of everyday life is still relatively limited. One constraint on doing such research is the need to provide participants with accelerometers to objectively record their exercise, and pagers to capture affective reports. Aims We aimed to develop a methodology for studying affect and exercise using only technology that participants already possess, namely GPS running watches and smartphones. Using this methodology, we aimed to characterize within-individual fluctuations in affective valence and arousal in relation to bouts of exercise, and explore possible moderators of these fluctuations. Methods We recruited a sample of 38 recreational runners. Participants provided daily affective reports for six weeks using their smartphones. Information on their runs was harvested from their own GPS devices via an online platform for athletes. Results Average valence and arousal were higher on days when the person had run than on the next day, and higher the day after a run than on the days after that. Over the course of the day of a run, valence and arousal declined significantly as the time since the run increased. Physically fitter participants had more positive valence overall, and this was particularly true when they had not run recently. There was some evidence of higher-dose (i.e., longer and faster) runs being associated with lower arousal on the next and subsequent days. Gender did not moderate associations between running and valence or arousal. Discussion Our study demonstrated the potential for studying the associations between affect and exercise in a way that is precise, undemanding for participants, and convenient for researchers, using technologies that participants already own and use.

A low-cost average valence detector for mixed electrolytes in vanadium flow batteries

An optical average valence detector has been developed to enable the capacity recovery of VFBs via electrolyte mixing and online electrolysis.