Recent Advances in Cerium Oxide-Based Memristors for Neuromorphic Computing.

This review article attempts to provide a comprehensive review of the recent progress in cerium oxide (CeO2)-based resistive random-access memories (RRAMs). CeO2 is considered the most promising candidate because of its multiple oxidation states (Ce3+ and Ce4+), remarkable resistive-switching (RS) uniformity in DC mode, gradual resistance transition, cycling endurance, long data-retention period, and utilization of the RS mechanism as a dielectric layer, thereby exhibiting potential for neuromorphic computing. In this context, a detailed study of the filamentary mechanisms and their types is required. Accordingly, extensive studies on unipolar, bipolar, and threshold memristive behaviors are reviewed in this work. Furthermore, electrode-based (both symmetric and asymmetric) engineering is focused for the memristor's structures such as single-layer, bilayer (as an oxygen barrier layer), and doped switching-layer-based memristors have been proved to be unique CeO2-based synaptic devices. Hence, neuromorphic applications comprising spike-based learning processes, potentiation and depression characteristics, potentiation motion and synaptic weight decay process, short-term plasticity, and long-term plasticity are intensively studied. More recently, because learning based on Pavlov's dog experiment has been adopted as an advanced synoptic study, it is one of the primary topics of this review. Finally, CeO2-based memristors are considered promising compared to previously reported memristors for advanced synaptic study in the future, particularly by utilizing high-dielectric-constant oxide memristors.

Lead induces DNA damage and alteration of ALAD and antioxidant genes mRNA expression in construction site workers.

Oxidative stress and DNA damage are considered as possible mechanisms involved in lead toxicity. To test this hypothesis, DNA damage and expression variations of aminolevulinic acid dehydratase (ALAD), superoxide dismutase 2 (SOD2), and 8-oxoguanine DNA glycosylase 2a (OGG1-2a) genes was studied in a cohort of 100 exposed workers and 100 controls with comet assay and real-time polymerse chain reaction (PCR). Results indicated that increased number of comets was observed in exposed workers versus controls (p < 0.001). After qPCR analysis, significant down-regulation in ALAD (p < 0.0001), SOD2 (p < 0.0001), and OGG1-2a (p < 0.0001) level was observed in exposed workers versus controls. Additionally, a positive spearmen correlation was observed between ALAD versus SOD2 (r = 0.402**, p < 0.001), ALAD versus OGG1-2a (r = 0.235*, p < 0.05), and SOD2 versus OGG1-2a (r = 0.292*, p < 0.05). This study showed that lead exposure induces DNA damage, which is accompanied by an elevated intensity of oxidative stress and expression variation of lead-related gene.

Correction: Qualitative analysis of biosurfactants from Bacillus species exhibiting antifungal activity.

[This corrects the article DOI: 10.1371/journal.pone.0198107.].

Qualitative analysis of biosurfactants from Bacillus species exhibiting antifungal activity.

Bacillus spp. produce a broad spectrum of lipopeptide biosurfactants, among which surfactin, iturin and fengycin are widely studied families. The goals of this study were to characterize the biosurfactant activity of Bacillus spp. and to investigate their motility and biofilm formation capabilities. In addition, we extracted lipopeptides from these bacteria to assess their antifungal activities and analyzed these products by mass spectrometry (MS). B. amyloliquefaciens FZB42, Bacillus sp. NH 217 and B. subtilis NH-100 exhibited excellent biosurfactant and surface spreading activities, whereas B. atrophaeus 176s and Paenibacillus polymyxa C1225 showed moderate activity, and B. subtilis 168 showed no activity. Strains FZB42, NH-100, NH-217, 176s and CC125 exhibited excellent biofilm formation capabilities. Lipopeptide extracts displayed good antifungal activity against various phytopathogens and their associated diseases, such as Fusarium moniliforme (rice bakanae disease), Fusarium oxysporum (root rot), Fusarium solani (root rot) and Trichoderma atroviride (ear rot and root rot). Lipopeptide extracts of these strains also showed hemolytic activity, demonstrating their strong potential to produce surfactants. LCMS-ESI analyses identified the presence of surfactin, iturin and fengycin in the extracts of Bacillus strains. Thus, the strains assayed in this study show potential as biocontrol agents against various Fusarium and Trichoderma species.