Ultralow Percolation Threshold in Nanoconfined Domains

Self-assembled percolated networks play an important role in many advanced electronic materials and devices. In nanocarbon composites, decreasing the percolation threshold ϕ_c is of paramount importance to reduce nanotube bundling, minimize material resources and costs, and enhance charge transport. Here we demonstrate that three-dimensional nanoconfinement in single-wall carbon nanotube/polymer nanocomposites produces a strong reduction in ϕ_c, reaching the lowest value ever reported in this system of ϕ_c ≈ 1.8 × 10^–5 wt % and 4–5 orders of magnitude lower than the theoretical statistical percolation threshold ϕ_stat. Moreover, a change in network resistivity and electrical conduction was observed with increased confinement, and a simple resistive model is used to accurately estimate the difference in ϕ_c in the confined networks. These results are explained in terms of networks’ size, confinement, and tube orientation as determined by atomic force microscopy, electrical conductivity measurements, and polarized Raman spectroscopy. Our findings provide important insight into nanoscale percolated networks and should find application in electronic nanocomposites and devices

Self-Assembled PCBM Nanosheets: A Facile Route to Electronic Layer-on-Layer Heterostructures

We report on the self-assembly of semicrystalline [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) nanosheets at the interface between a hydrophobic solvent and water, and utilize this opportunity for the realization of electronically active organic/organic molecular heterostructures. The self-assembled PCBM nanosheets can feature a lateral size of >1 cm² and be transferred from the water surface to both hydrophobic and hydrophilic surfaces using facile transfer techniques. We employ a transferred single PCBM nanosheet as the active material in a field-effect transistor (FET) and verify semiconductor function by a measured electron mobility of 1.2 × 10^–2 cm² V^–1 s^–1 and an on–off ratio of ∼1 × 10⁴. We further fabricate a planar organic/organic heterostructure with the p-type organic semiconductor poly­(3-hexylthiophene-2,5-diyl) as the bottom layer and the n-type PCBM nanosheet as the top layer and demonstrate ambipolar FET operation with an electron mobility of 8.7 × 10^–4 cm² V^–1 s^–1 and a hole mobility of 3.1 × 10^–4 cm² V^–1 s^–1

Enriched functional categories (GO terms) for genes differentially expressed after HFS vs 6-OHDA, with the constituting genes and their fold change (FC).

<p>Abbreviations: GO: gene ontology; BP: biological process; CC: cell. component.</p

Comparison of the data obtained by microarray and RT-qPCR for 6 genes of interest.

<p>(A) Genes specifically up-regulated by HFS, (B) opposite regulation of <i>Pkrcd</i> by HFS and DOPA and (C) common down-regulation of <i>Sirt5</i> by HFS and DOPA. Microarray experiments were performed on total striatal RNA samples from 6-OHDA, HFS, DOPA and DOPA/HFS groups. For qPCR validation of gene expression, total striatal RNA samples from 3 groups were analyzed: control, 6-OHDA and HFS. For both microarray and qPCR, results were calculated for each sample relative to the expression of the endogenous reference gene: HPRT, and fold change vs the 6-OHDA group was determined using the 2^−ΔΔCt method. Values are presented as means ± SEM. *p<0.05 vs 6-OHDA values.</p

Venn diagram showing the numbers of genes specifically or commonly altered by the treatments.

<p>Venn diagram showing the numbers of genes specifically or commonly altered by the treatments.</p

STN HFS alleviates akinesia and exacerbates L-DOPA-induced dyskinesia.

<p>(A) Akinesia was assessed by forelimb asymmetry in the cylinder test in the control and 6-OHDA groups and in the HFS group before the stimulation (pre-HFS) and after 5 days of stimulation (HFS-ON). Forelimb asymmetry was calculated as the % contralateral minus % ipsilateral forepaw contacts (*p<0.05 HFS ON vs. pre-HFS). (B) Analysis of AIMs was performed in DOPA and DOPA/HFS groups. Dyskinesia score corresponds to the sum of the orolingual and forelimb AIM scores (maximum 8). The data are the means ± SEM, *<i>p</i><0.05 DOPA/HFS vs DOPA.</p

KEGG metabolic pathways for genes differentially regulated in HFS, DOPA and DOPA/HFS groups vs 6-OHDA.

<p>KEGG metabolic pathways for genes differentially regulated in HFS, DOPA and DOPA/HFS groups vs 6-OHDA.</p

Photomicrograph illustrating the electrode placement in the STN.

<p>Subthalamic nucleus was outlined by the white dotted line. The black arrows show the location of the bared electrode tips delivering HFS in the STN. CP, cerebral peduncle.</p

Influence of Sb⁵⁺ as a Double Donor on Hematite (Fe³⁺) Photoanodes for Surface-Enhanced Photoelectrochemical Water Oxidation

To exploit the full potential of hematite (α-Fe₂O₃) as an efficient photoanode for water oxidation, the redox processes occurring at the Fe₂O₃/electrolyte interface need to be studied in greater detail. Ex situ doping is an excellent technique to introduce dopants onto the photoanode surface and to modify the photoanode/electrolyte interface. In this context, we selected antimony (Sb⁵⁺) as the ex situ dopant because it is an effective electron donor and reduces recombination effects and concurrently utilize the possibility to tuning the surface charge and wettability. In the presence of Sb⁵⁺ states in Sb-doped Fe₂O₃ photoanodes, as confirmed by X-ray photoelectron spectroscopy, we observed a 10-fold increase in carrier concentration (1.1 × 10²⁰ vs 1.3 × 10¹⁹ cm^–3) and decreased photoanode/electrolyte charge transfer resistance (∼990 vs ∼3700 Ω). Furthermore, a broad range of surface characterization techniques such as Fourier-transform infrared spectroscopy, ζ-potential, and contact angle measurements reveal that changes in the surface hydroxyl groups following the ex situ doping also have an effect on the water splitting capability. Theoretical calculations suggest that Sb⁵⁺ can activate multiple Fe³⁺ ions simultaneously, in addition to increasing the surface charge and enhancing the electron/hole transport properties. To a greater extent, the Sb⁵⁺- surface-doped determines the interfacial properties of electrochemical charge transfer, leading to an efficient water oxidation mechanism

Differential MicroRNA Expression Profile between Stimulated PBMCs from HIV-1 Infected Elite Controllers and Viremic Progressors

<div><p>Background</p><p>The emerging relationship between microRNAs (miRNA) and viral-control is a topic of interest in the field of HIV. Host-genome might play an important role in the control of viremia. The aim of this study was to assess the specific miRNA profile that could contribute to the control of HIV replication in Elite Controllers</p><p>Results</p><p>After adequate normalization, expression profile of 286 human miRNAs (hsa-miR) was evaluated in phytohaemagglutinin-stimulated PBMCs from 29 individuals classified in 4 groups: 8 elite controllers (EC; viral load <50 cp/ml without treatment), 8 viremic progressors (VP; VL>5000 cp/ml without treatment), 8 patients under antiretroviral treatment (ART; VL<200 cp/ml) and 5 uninfected individuals (HIV-) through TaqMan Array Human microRNA Cards v3.0. A differential expression pattern consisting of 23 miRNAs became significantly different when comparing EC and VP. Profiling analysis segregated the population in two different blocks: while EC and HIV- clustered together in the same block (EC/HIV-_block 1), VP and ART individuals clustered together in a second block (VP/ART_block 2). Two inversely expressed miRNA patterns were determined within those two blocks: a set of 4 miRNAs (hsa-miR-221, -27a, -27b and -29b) was up-expressed in EC/HIV-_block and down-expressed in VP/ART_block while 19 miRNAs were down-expressed in block 1 and up-expressed in block 2. Differential miRNAs were successfully validated through individual RT-qPCR assays.</p><p>Conclusions</p><p>Profile in EC resembled HIV- and differentially clusters with VP and ART. Therefore, differential clustering does not rely on undetectable viremia.</p></div