An Exploration of Potential Pathways Toward Emerging Electronic Devices with Ferroelectric Materials

In the relentless pursuit of Moore's law, device scaling down to the nanometer regime has gradually reached a bottleneck as the power dissipation in microchips becomes a more and more challenging concern. Therefore, emerging technologies beyond CMOS are in urgent need of development. Among many proposed emerging devices, we primarily focus our research attention on the negative capacitance phenomenon in ferroelectrics and the magnetoelectric effect in multiferroics for low power device applications in this thesis. To assess the potential application of the negative capacitance effect, we first implement a physics-based circuit-compatible model of single domain ferroelectric materials for the study of the performance of negative capacitance field-effect transistors at the device and circuit levels. The single domain ferroelectric model is further extended to a multi-domain model by adopting the phase field formalism to capture the polycrystalline nature of ferroelectric films. For realistic logic device applications, however, the physical mechanisms behind the experimental observation of hysteresis-free negative capacitance behaviors have not yet been clear. Therefore, we dedicate our research efforts to the study of such a key phenomenon for the realization of ultra-low power negative capacitance field effect transistors. In addition, with proper free energy contributions included to describe the experimentally observed two-step polarization switching process in bismuth ferrite, a unified micromagnetic/ferroelectric simulation framework is developed to model the deterministic switching dynamics and thermal stability of the single-domain BFO/CoFe heterojunction. Lastly, a comprehensive thesis overview and the important topics for future works are given, especially the trapped charge dynamics in ferroelectric field effect transistors, which is the major reliability concern for the memory device realization.Ph.D

Factors Affecting Sesame Seed Exports in Burkina Faso: The Vector Error Correction Approach

The research is financed by Academia Sinica, Taiwan. Grant No. AS-SS-107-02. Abstract Burkina Faso's (BFA) dependence on a single export crop, namely cotton, has so far threatened its economy since the fluctuating and uncontrollable drops in world cotton prices. The diversification of cash crops has become a national priority that is appropriated day by day by actors of rural development, and more particularly by farmers seeking to improve and secure their income. Thus, export crops, such as sesame, appear obvious and essential, not only for farmers’ income security but also for the country by its ability to attract currencies. In the last decade, BFA’s the sesame sector has recorded a tremendous growth both in quantity and value of exports to being the eighth world largest exporter of sesame seed. Considering its unequaled performance in the export of sesame seed, we deemed relevant to identify the key factors affecting that performance and to study their effects on sesame seed export earnings in order to draft appropriated policies aimed to enhance the country’s earnings. This study uses the cointegration approach, and has purposely designed exports value as the independent variable to analyze the country exports performance using time series data for the period of 47 years (1970-2016). One cointegration vector is found between the variables employed; thereby the Vector Error Correction Model has been performed. The empirical results reveal that nominal exchange rate, producer price, world export volume of sesame seed as a proxy of world demand, and world price are key factors affecting significantly the country’s exports performance in the short-run. Moreover, in the long-run nominal exchange rate, production, producer price, and world export price are factors determining significantly export earnings of sesame seed in Burkina Faso. For Burkina Faso to increase its market shares and export earnings, especially in the long-run, it is principally recommended to boost the production by increasing significantly yields and ensure an appropriate transmission of international prices increments to farmers. Keywords: Agricultural Export, Determinants of Agricultural Exports, Sesame Seed, Cointegration, Burkina Faso. DOI: 10.7176/DCS/10-4-03 Publication date: April 30th 202

Poly[bis­(μ2-4,4′-bipyridine)­bis­(3-nitro­benzoato)nickel(II)]

The crystal structure of the title complex, [Ni(C7H4NO4)2(C10H8N2)2]n, exhibits a two-dimensional network, which is built up from slightly distorted NiN4O2 polyhedra (2 symmetry), bipyridine ligands, and carboxyl­ate anions. The NiII atoms are six-coordinated by two O atoms of two monodentate carboxyl­ate anions and four N atoms from bipyridine ligands and are connected into layers by the 4,4′-bipyridine ligands

Outcome and prognostic factors in critically ill patients with systemic lupus erythematosus: a retrospective study

INTRODUCTION: Systemic lupus erythematosus (SLE) is an archetypal autoimmune disease, involving multiple organ systems with varying course and prognosis. However, there is a paucity of clinical data regarding prognostic factors in SLE patients admitted to the intensive care unit (ICU). METHODS: From January 1992 to December 2000, all patients admitted to the ICU with a diagnosis of SLE were included. Patients were excluded if the diagnosis of SLE was established at or after ICU admission. A multivariate logistic regression model was applied using Acute Physiology and Chronic Health Evaluation II scores and variables that were at least moderately associated (P < 0.2) with survival in the univariate analysis. RESULTS: A total of 51 patients meeting the criteria were included. The mortality rate was 47%. The most common cause of admission was pneumonia with acute respiratory distress syndrome. Multivariate logistic regression analysis showed that intracranial haemorrhage occurring while the patient was in the ICU (relative risk = 18.68), complicating gastrointestinal bleeding (relative risk = 6.97) and concurrent septic shock (relative risk = 77.06) were associated with greater risk of dying, whereas causes of ICU admission and Acute Physiology and Chronic Health Evaluation II score were not significantly associated with death. CONCLUSION: The mortality rate in critically ill SLE patients was high. Gastrointestinal bleeding, intracranial haemorrhage and septic shock were significant prognostic factors in SLE patients admitted to the ICU

The game L(d,1)-labeling problem of graphs

AbstractLet G be a graph and let k be a positive integer. Consider the following two-person game which is played on G: Alice and Bob alternate turns. A move consists of selecting an unlabeled vertex v of G and assigning it a number a from {0,1,2,…,k} satisfying the condition that, for all u∈V(G),u is labeled by the number b previously, if d(u,v)=1, then |a−b|≥d, and if d(u,v)=2, then |a−b|≥1. Alice wins if all the vertices of G are successfully labeled. Bob wins if an impasse is reached before all vertices in the graph are labeled. The game L(d,1)-labeling number of a graph G is the least k for which Alice has a winning strategy. We use λ̃1d(G) to denote the game L(d,1)-labeling number of G in the game Alice plays first, and use λ̃2d(G) to denote the game L(d,1)-labeling number of G in the game Bob plays first. In this paper, we study the game L(d,1)-labeling numbers of graphs. We give formulas for λ̃1d(Kn) and λ̃2d(Kn), and give formulas for λ̃1d(Km,n) for those d with d≥max{m,n}

miRTar: an integrated system for identifying miRNA-target interactions in human

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are small non-coding RNA molecules that are ~22-nt-long sequences capable of suppressing protein synthesis. Previous research has suggested that miRNAs regulate 30% or more of the human protein-coding genes. The aim of this work is to consider various analyzing scenarios in the identification of miRNA-target interactions, as well as to provide an integrated system that will aid in facilitating investigation on the influence of miRNA targets by alternative splicing and the biological function of miRNAs in biological pathways.</p> <p>Results</p> <p>This work presents an integrated system, miRTar, which adopts various analyzing scenarios to identify putative miRNA target sites of the gene transcripts and elucidates the biological functions of miRNAs toward their targets in biological pathways. The system has three major features. First, the prediction system is able to consider various analyzing scenarios (1 miRNA:1 gene, 1:N, N:1, N:M, all miRNAs:N genes, and N miRNAs: genes involved in a pathway) to easily identify the regulatory relationships between interesting miRNAs and their targets, in 3'UTR, 5'UTR and coding regions. Second, miRTar can analyze and highlight a group of miRNA-regulated genes that participate in particular KEGG pathways to elucidate the biological roles of miRNAs in biological pathways. Third, miRTar can provide further information for elucidating the miRNA regulation, i.e., miRNA-target interactions, affected by alternative splicing.</p> <p>Conclusions</p> <p>In this work, we developed an integrated resource, miRTar, to enable biologists to easily identify the biological functions and regulatory relationships between a group of known/putative miRNAs and protein coding genes. miRTar is now available at <url>http://miRTar.mbc.nctu.edu.tw/</url>.</p

Topological surface electronic states in candidate nodal-line semimetal CaAgAs

We investigate systematically the bulk and surface electronic structure of the candidate nodal-line semimetal CaAgAs by angle resolved photoemission spectroscopy and density functional calculations. We observed a metallic, linear, non-$k_z$-dispersive surface band that coincides with the high-binding-energy part of the theoretical topological surface state, proving the topological nontriviality of the system. An overall downshift of the experimental Fermi level points to a rigid-band-like $p$-doping of the samples, due possibly to Ag vacancies in the as-grown crystals.Comment: 6 pages, 5 figure

Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

<p>Abstract</p> <p>Purpose</p> <p>This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from <it>Michelia compressa</it>, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC) cells.</p> <p>Methods</p> <p>The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10) by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay.</p> <p>Results</p> <p>Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10)-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68), phosphorylated Cdc25c (Ser 216), phosphorylated Cdk1 (Tyr 15) and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9.</p> <p>Conclusions</p> <p>Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells.</p