RESISTIVE SWITCHING IN TIO2 FOR MEMORY APPLICATIONS

Ph.DDOCTOR OF PHILOSOPH

Catalyst-Free and Highly Selective N,N-Diallylation of Anilines in Aqueous Phase

A highly selective diallylation reaction of anilines with allyl bromide was achieved in aqueous alcohol solution in the presence of potassium carbonate and without the use of any catalyst. The reaction tolerates a wide range of functionalities, and various tertiary amines were obtained in the yield of up to 99% with complete conversion of anilines

ATF4 promotes brain vascular smooth muscle cells proliferation, invasion and migration by targeting miR-552-SKI axis.

BackgroundStudies have indicated vascular smooth muscle cells (VSMCs) played a crucial role in atherosclerosis and microRNAs (miRNAs) played key roles in biological functions of VSMCs. Whereas, the potential function and mechanism of miR-552 in VSMCs remains unclear. Our aim was to explore the role of miR-552 on VSMCs and underlying mechanism.Material/methodsMTT assay and transwell assay were used to measure the proliferation, invasion, and migration of human brain VSMCs (HBVSMCs) and mice VSMCs (mVSMCs), respectively. Bioinformatics tools and luciferase assay were adopted to verify the association between miR-552 and SKI. Rescue experiments were employed to assess the interaction of miR-552 and SKI in modulating biological functions in HBVSMCs and mVSMCs. The expression level of transcription factors (TFs)was measured via qRT-PCR assay. The effect of ATF4 on miR-552 and SKI expression was tested by qRT-PCR or western blot assay. Finally, chromatin immunoprecipitation (ChIP) assay and JASPAR databases were used to analyze the regulatory linkage between ATF4 and miR-552.ResultsWe found that miR-552 was upregulated in HBVSMCs treated with PDGF-bb and miR-552 overexpression could promote proliferation, invasion, and migration of HBVSMCs and mVSMCs, whereas, miR-552 knockdown had the opposite impact. In addition, we also found that SKI was a direct target of miR-552, which reversed miR-552-mediated proliferation, invasion, and migration in HBVSMCs and mVSMCs. Furthermore, we also discovered that miR-552 overexpression promoted the effects of ATF4 elevation on proliferation, migration and invasion of HBVSMCs and mVSMCs, but, miR-552 decline had the opposite impact.ConclusionsATF4-miR-552-SKI axis played critical roles in the proliferation and migration of HBVSMCs and mVSMCs, which were closely involved in atherosclerosis (AS). Therefore, our findings might offer a novel therapeutic target for AS

The complete mitochondrial genome of Meloe proscarabaeus (Coleoptera, Meloidae): genome descriptions and phylogenetic inferences

Oil beetles are meloids, which are characterised for their cleptoparasitic habits in bee nests and oily fluid of cantharidin that causes blistering and swelling of the skin. The complete mitochondrial genome of Meloe proscarabaeus is determined using the next-generation sequencing technology and its genomic characteristics are described. The 15,653-bp long genome is a circular molecule consisting of 13 protein-coding genes (PCG), 22 transport RNA, two ribosomal RNA, and a control region. The A + T bias of the mitochondrial genome is manifested in the complete sequence and the codon usage of protein-coding genes. The genetic distance within and between genera is calculated to confirm the taxonomic status of M. proscarabaeus. The phylogenetic relationships among 15 available meloid taxa are inferred by the maximum likelihood (ML) method based on 13 mitochondrial PCGs. The ML trees resulting from nucleotide and amino acid datasets recover both the monophyly of Meloe and Epicauta and the polyphyly comprising Hycleus and Mylabris. This study provides the first description of a mitochondrial genome belonging to the genus Meloe. The mitochondrial genome sequence and its characteristics are expected to be conducive to future studies on taxonomy, systematics, and molecular phylogenetics of the family Meloidae

Frequency-dependent synapse weight tuning in 1S1R with short-term plasticity TiOx-based exponential selector

Short-term plasticity (STP) is an important synaptic characteristic in the hardware implementation of artificial neural networks (ANN), as it enables the temporal information processing (TIP) capability. However, the STP feature is rather challenging to reproduce from a single non-volatile resistive random-access memory (RRAM) element, as it requires a certain degree of volatility. In this work, a Pt/TiOx/Pt exponential selector is introduced not only to suppress the sneak current, but also to enable the TIP feature in a one selector-one RRAM (1S1R) synaptic device. Our measurements reveal that the exponential selector exhibits the STP characteristic, while a Pt/HfOx/Ti RRAM enables the long-term memory capability of the synapse. Thereafter, we experimentally demonstrated pulse frequency-dependent multilevel switching in the 1S1R device, exhibiting the TIP capability of the developed 1S1R synapse. The observed STP of the selector is strongly influenced by the bottom metal-oxide interface, in which Ar plasma treatment on the bottom Pt electrode show the annihilation of the STP feature in the selector. A mechanism is thus proposed to explain the observed STP, using the local electric field enhancement induced at the metal-oxide interface coupled with the drift-diffusion model of mobile O2- and Ti3+ ions. This work therefore provides a reliable means of producing the STP feature in a 1S1R device, which demonstrates the TIP capability sought after in hardware-based ANN.Agency for Science, Technology and Research (A*STAR)Submitted/Accepted versionThis work was supported by a RIE2020 ASTAR AME IAF-ICP Grant (No.I1801E0030)

Space-Charge-Mediated Anomalous Ferroelectric Switching in P(VDF–TrEE) Polymer Films

We report on the switching dynamics of P­(VDF–TrEE) copolymer devices and the realization of additional substable ferroelectric states via modulation of the coupling between polarizations and space charges. The space-charge-limited current is revealed to be the dominant leakage mechanism in such organic ferroelectric devices, and electrostatic interactions due to space charges lead to the emergence of anomalous ferroelectric loops. The reliable control of ferroelectric switching in P­(VDF–TrEE) copolymers opens doors toward engineering advanced organic memories with tailored switching characteristics

Symmetrical negative differential resistance behavior of a resistive switching device

10.1021/nn204907tACS Nano632517-252