Photoresponse of polyaniline-functionalized graphene quantum dots

Polyaniline-functionalized graphene quantum dots (PANI-GQD) and pristine graphene quantum dots (GQDs) were utilized for optoelectronic devices. The PANI-GQD based photodetector exhibited higher responsivity which is about an order of magnitude at 405 nm and 7 folds at 532 nm as compared to GQD-based photodetectors. The improved photoresponse is attributed to the enhanced interconnection of GQD by island-like polymer matrices, which facilitate carrier transport within the polymer matrices. The optically tunable current–voltage (I–V) hysteresis of PANI-GQD was also demonstrated. The hysteresis magnifies progressively with light intensity at a scan range of ±1 V. Both GQD and PANI-GQD devices change from positive to negative photocurrent when the bias reaches 4 V. Photogenerated carriers are excited to the trapping states in GQDs with increased bias. The trapped charges interact with charges injected from the electrodes which results in a net decrease of free charge carriers and a negative photocurrent. The photocurrent switching phenomenon in GQD and PANI-GQD devices may open up novel applications in optoelectronics

Self-passivated freestanding superconducting oxide film for flexible electronics

The integration of high-temperature superconducting YBa2Cu3O6+x (YBCO) into flexible electronic devices has the potential to revolutionize the technology industry. The effective preparation of high-quality flexible YBCO films therefore plays a key role in this development. We present a novel approach for transferring water-sensitive YBCO films onto flexible substrates without any buffer layer. Freestanding YBCO film on a polydimethylsiloxane substrate is extracted by etching the Sr3Al2O6 sacrificial layer from the LaAlO3 substrate. In addition to the obtained freestanding YBCO thin film having a Tc of 89.1 K, the freestanding YBCO thin films under inward and outward bending conditions have Tc of 89.6 K and 88.9 K, respectively. A comprehensive characterization involving multiple experimental techniques including high-resolution transmission electron microscopy, scanning electron microscopy, Raman and X-ray Absorption Spectroscopy is conducted to investigate the morphology, structural and electronic properties of the YBCO film before and after the extraction process where it shows the preservation of the structural and superconductive properties of the freestanding YBCO virtually in its pristine state. Further investigation reveals the formation of a YBCO passivated layer serves as a protective layer which effectively preserves the inner section of the freestanding YBCO during the etching process. This work plays a key role in actualizing the fabrication of flexible oxide thin films and opens up new possibilities for a diverse range of device applications involving thin-films and low-dimensional materials.Comment: 22 pages,4 figures,references adde

Direct observation of two-dimensional small polarons at correlated oxide interface

Two-dimensional (2D) perovskite oxide interfaces are ideal systems where diverse emergent properties can be uncovered.The formation and modification of polaronic properties due to short-range strong charge-lattice interactions of 2D interfaces remains hugely intriguing.Here, we report the direct observation of small-polarons at the LaAlO3/SrTiO3 (LAO/STO) conducting interface using high-resolution spectroscopic ellipsometry.First-principles investigations further reveals that strong coupling between the interfacial electrons and the Ti-lattice result in the formation of localized 2D small polarons.These findings resolve the longstanding issue where the excess experimentally measured interfacial carrier density is significantly lower than theoretically predicted values.The charge-phonon induced lattice distortion further provides an analogue to the superconductive states in magic-angle twisted bilayer graphene attributed to the many-body correlations induced by broken periodic lattice symmetry.Our study sheds light on the multifaceted complexity of broken periodic lattice induced quasi-particle effects and its relationship with superconductivity

Mitochondrial Apoptosis and FAK Signaling Disruption by a Novel Histone Deacetylase Inhibitor, HTPB, in Antitumor and Antimetastatic Mouse Models

BACKGROUND: Compound targeting histone deacetylase (HDAC) represents a new era in molecular cancer therapeutics. However, effective HDAC inhibitors for the treatment of solid tumors remain to be developed. METHODOLOGY/PRINCIPAL FINDINGS: Here, we propose a novel HDAC inhibitor, N-Hydroxy-4-(4-phenylbutyryl-amino) benzamide (HTPB), as a potential chemotherapeutic drug for solid tumors. The HDAC inhibition of HTPB was confirmed using HDAC activity assay. The antiproliferative and anti-migratory mechanisms of HTPB were investigated by cell proliferation, flow cytometry, DNA ladder, caspase activity, Rho activity, F-actin polymerization, and gelatin-zymography for matrix metalloproteinases (MMPs). Mice with tumor xenograft and experimental metastasis model were used to evaluate effects on tumor growth and metastasis. Our results indicated that HTPB was a pan-HDAC inhibitor in suppressing cell viability specifically of lung cancer cells but not of the normal lung cells. Upon HTPB treatment, cell cycle arrest was induced and subsequently led to mitochondria-mediated apoptosis. HTPB disrupted F-actin dynamics via downregulating RhoA activity. Moreover, HTPB inhibited activity of MMP2 and MMP9, reduced integrin-β1/focal adhesion complex formation and decreased pericellular poly-fibronectin assemblies. Finally, intraperitoneal injection or oral administration of HTPB efficiently inhibited A549 xenograft tumor growth in vivo without side effects. HTPB delayed lung metastasis of 4T1 mouse breast cancer cells. Acetylation of histone and non-histone proteins, induction of apoptotic-related proteins and de-phosphorylation of focal adhesion kinase were confirmed in treated mice. CONCLUSIONS/SIGNIFICANCE: These results suggested that intrinsic apoptotic pathway may involve in anti-tumor growth effects of HTPB in lung cancer cells. HTPB significantly suppresses tumor metastasis partly through inhibition of integrin-β1/FAK/MMP/RhoA/F-actin pathways. We have provided convincing preclinical evidence that HTPB is a potent HDAC targeted inhibitor and is thus a promising candidate for lung cancer chemotherapy

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

STUDY OF ELECTRONIC STRUCTURES & CORRELATIONS IN TWO-DIMENSIONAL TRANSITION METAL DICHALCOGENIDES USING SPECTROSCOPIC ELLIPSOMETRY

Ph.DDOCTOR OF PHILOSOPHY (NGS

Optical studies of topological insulator Bi1:5 Sb0:5 Te1:8 Se1:2 using terahertz time-domain spectroscopy.

Topological insulators are insulating materials with conducting surface states and insulating bulk states. Their surface states are topologically protected, meaning that unlike ordinary surface states, they cannot be destroyed by impurities and imperfections. This property is attributed to the presence of time-reversal symmetry and spin-orbit interaction, which occurs in heavy elements such as mercury and bismuth. Topological insulators are currently one of the main focuses of condensed matter research. Using Terahertz Time-Domain Spectroscopy (THz-TDS), we studied the optical properties of 3D topological insulator Bi_$1:5$Sb_$0:5$Te_$1:8$Se_$1:2$ (BSTS). Measurements have been carried out using a THz-TDS Spectrometer of spectral range 0.4-3.5 THz with temperatures between 5 K and 150 K. By tting the material conductance to the Drude-Lorentz Model, it allows us to understand the optical properties and charged carrier dynamics of the topological insulator. Thus, enabling us to characterize both the bulk and the surface states of the material. Results have shown temperature-dependence in the conductance (G), plasma frequencies (wp) and scattering rates (gamma). We attribute a signi ficant contribution of the surface states to the Drude conductance while the Lorentz conductance to the bulk insulating state. This gives a clearer understanding on how the surface charged carriers evolve with temperature.Bachelor of Science in Physic

Representação de Macau na tradução e no reconto : a perspetiva do orientalismo

Este trabalho investiga dois livros que fazem parte da literatura de Macau do último meio século. Ambos são coleções de contos e retratam a vida das mulheres nas sociedades chinesa e macaense por volta dos anos 40 e 50 do século XX. Cheong-Sam, a Cabaia é escrita por Deolinda da Conceição, uma autora portuguesa que cresceu em Macau e escreveu em Português; a tradução é feita por Yao Jingming, de português para chinês. O outro livro, Amores do Céu e da Terra, é uma obra de Ling Ling, uma escritora local de Macau que escreve em chinês; a versão em português da obra é uma colaboração entre a tradutora Stella Lee e a autora de reconto Fernanda Dias. A dissertação visa estudar a representação da sociedade e da cultura de Macau em ambos os casos e questionar até que ponto esta representação envolve uma ótica do orientalismo. Para o primeiro caso, a escrita, ou seja, a autotradução da escritora portuguesa para o público português (a primeira publicação foi em Lisboa) vai ser destacada. No segundo caso, o foco será especialmente o processo de recontar da obra que envolve a colaboração de duas profissionais. O facto de a tradução ser chamada de “reconto” é o principal aspeto a ser analisado a esse respeito. Através da análise e comparação dos processos de tradução dos dois livros, pretendo explorar a natureza da tradução, a função do tradutor e a figura do “autor de reconto”, sobretudo em relação à forma como as escolhas do tradutor podem manipular a representação da cultura chinesa/portuguesa e influenciar a receção dessa cultura pelo público-alvo, na mediação entre dois universos culturais, apelando também a atenção ao valor das obras literária de Macau.This paper investigates two books that are part of literature of Macao of the last half century. Both are collections of short stories and depict women’s lives in Chinese and Macanese society around the 40’s and 50’s of the 20th century. Cheong-Sam, a Cabaia is written by Deolinda da Conceição, a Portuguese writer who grew up in Macao and wrote in Portuguese; the translation is made by Yao Jingming from Portuguese to Chinese. Another book Amores do Céu e da Terra is written by Ling Ling, a local writer of Macao who writes in Chinese; the Portuguese version of the work is a collaboration between the translator Stella Lee and the rewriter Fernanda Dias. The dissertation aims at studying the representation of Macanese society and culture in both cases and to question in how far this representation involves an optic of orientalism. In the first case, the writing, that is, the Portuguese writer’s self-translation for the Portuguese public readers (the first publication in Lisbon) will be highlighted. In the second case, the focus will be especially on the retelling process of the work, which involves the collaboration of two professionals. The fact that the translation is named a “retelling” is the first aspect to analyse in this regard. Through the analyses and comparison of the processes of translation of these two books, I aim at finding out further the nature of translation and the function of translator and rewriter, especially on how the translator’s choices can manipulate the representation of the Chinese/Portuguese culture and influence the reception of that culture by the target audience, in mediation between two cultural universes, also calling attention to the value of Macao’s literary works