Investigating female versus male differences in white matter neuroplasticity associated with complex visuo-motor learning

Magnetic resonance imaging (MRI) has increasingly been used to characterize structure-function relationships during white matter neuroplasticity. Biological sex differences may be an important factor that affects patterns of neuroplasticity, and therefore impacts learning and rehabilitation. The current study examined a participant cohort before and after visuo-motor training to characterize sex differences in microstructural measures. The participants (N = 27) completed a 10-session (4 week) complex visuo-motor training task with their non-dominant hand. All participants significantly improved movement speed and their movement speed variability over the training period. White matter neuroplasticity in females and males was examined using fractional anisotropy (FA) and myelin water fraction (MWF) along the cortico-spinal tract (CST) and the corpus callosum (CC). FA values showed significant differences in the middle portion of the CST tract (nodes 38-51) across the training period. MWF showed a similar cluster in the inferior portion of the tract (nodes 18-29) but did not reach significance. Additionally, at baseline, males showed significantly higher levels of MWF measures in the middle body of the CC. Combining data from females and males would have resulted in reduced sensitivity, making it harder to detect differences in neuroplasticity. These findings offer initial insights into possible female versus male differences in white matter neuroplasticity during motor learning. This warrants investigations into specific patterns of white matter neuroplasticity for females versus males across the lifespan. Understanding biological sex-specific differences in white matter neuroplasticity may have significant implications for the interpretation of change associated with learning or rehabilitation.

Electrodeposition of PdPt Nanoparticles on Edges and S-Vacancies in Exfoliated MoS2 Nanosheets for Enhanced Hydrogen Evolution Activity

Deposition of metal nanoparticles onto the molybdenum disulfide (MoS2 ) nanosheets is an efficient method to tune the electronic structure of the MoS2 and maximize its catalytic performance towards the hydrogen evolution reaction (HER). Herein, we report the electrodeposition of Pd and Pt nanoparticles onto desulfurized MoS2 nanosheets (MoS2-x ) to achieve an improved HER activity in an acidic electrolyte. The initial MoS2 powder was exfoliated and isolated through centrifugation, followed by electrochemical desulfurization to create defect sites. Subsequently, Pt and Pd nanoparticles were electrodeposited onto the S-vacancies of MoS2-x nanosheets. The resulting PdPt nanoparticles, with a diameter of 3.3 ±1.7 nm, were distributed across the surfaces of the nanosheets. A preferential deposition was evident at the edges of the nanosheets, particularly when Pd was deposited first followed by Pt. Owing to this preferential deposition of Pd and Pt and the synergistic interaction of MoS2-x with Pd and Pt, the prepared catalyst exhibited a low overpotential of 30 mV at 10 mA cm-2 , which is 2.7× lower than the MoS2-x alone. The prepared catalyst exhibited a 1.7× increase in the mass activity at 20 mV overpotential, relative to that of a commercial Pt/C nanocatalyst, showcasing its promising potential as an alternative catalyst.

HIV reservoirs are dominated by genetically younger and clonally enriched proviruses

IMPORTANCE

Characterizing the human immunodeficiency virus (HIV) reservoir that endures despite antiretroviral therapy (ART) is critical to cure efforts. We observed that the oldest proviruses persisting during ART were exclusively defective, while intact proviruses (and rebound HIV) dated to nearer ART initiation. This helps explain why studies that sampled sub-genomic proviruses on-ART (which are largely defective) routinely found sequences dating to early infection, whereas those that sampled replication-competent HIV found almost none. Together with our findings that intact proviruses were more likely to be clonal, and that on-ART low-level/isolated viremia originated from proviruses of varying ages (including possibly defective ones), our observations indicate that (i) on-ART and rebound viremia can have distinct within-host origins, (ii) intact proviruses have shorter lifespans than grossly defective ones and thus depend more heavily on clonal expansion for persistence, and (iii) an HIV reservoir predominantly "dating" to near ART initiation will be substantially adapted to within-host pressures, complicating immune-based cure strategies.

Manipulating the Self-Assembly of Multicomponent Low Molecular Weight Gelators (LMWGs) through Molecular Design

Multicomponent low molecular weight gelators (LMWGs) may self-assemble by co-assembly (CA), social self-sorting (SSS), or narcissistic self-sorting (NSS). Understanding the nuances of the self-assembly processes is important to predict the behavior of multicomponent organogels. Here, we investigate the effect of molecular structure on self-assembly in a series of amino-acid based bicomponent LMWGs that differ in headgroup and alkyl chain length. Packing preference of the organogels was determined using differential scanning calorimetry, nuclear magnetic resonance spectroscopy and small angle X-ray scattering. From 66 bicomponent samples we found 50 CA, 14 SSS and 2 NSS. Furthermore, we performed statistical analysis to investigate the role of hydrophobicity and chain length on the overall pathway of self-assembly for these systems. We found the hydrophobicity of the headgroup strongly affected the assembly preference of the organogel, but alkyl chain length only played a small role.