Proton-transfer Ferroelectricity / Multiferroicity in Rutile Oxyhydroxides

Oxyhydroxide minerals like FeOOH have been a research focus in geology for studying the Earth interior, and also in chemistry for studying oxygen electrocatalysis activity. In this paper we provide first-principles evidence of a new class of ferroelectrics or multiferroics among them:GaOOH,InOOH,CrOOH,FeOOH, which are earth-abundant minerals and have been experimentally verified to possess distorted rutile structures, are ferroelectric with considerable polarizations(up to 24 muC/cm2) and piezoelectric coefficients. Their atomic-thick layer may possess vertical polarization robust against depolarizing field due to the formation of O-H O bonds that can hardly be symmetrized. Moreover,CrOOH (guyanaite) is revealed to be a combination of high-Tc in-plane type-I multiferroics and vertical type-II multiferroics, which is strain-tunable and may render a desirable coupling between magnetism and ferroelectricity. Supported by experimental evidence on reversible conversion between metal oxyhydroxides and dioxides and their nice lattice match that renders convenient epitaxial growth, heterostructure composed of oxyhydroxides and prevalent metal dioxides (e.g. TiO2, SnO2 and CrO2) may be constructed for various applications like ferroelectric field-effect transistors and multiferroic tunneling junctions

Brownian Motion and Entropic Torque Driven Motion of Domain-Wall in Antiferromagnets

We study the spin dynamics in antiferromagnetic nanowire under an applied temperature gradient using micromagnetic simulations on a classical spin model with a uniaxial anisotropy. The entropic torque driven domain-wall motion and the Brownian motion are discussed in detail, and their competition determines the antiferromagnetic wall motion towards the hotter or colder region. Furthermore, the spin dynamics in an antiferromagnet can be well tuned by the anisotropy and the temperature gradient. Thus, this paper not only strengthens the main conclusions obtained in earlier works [Kim et al., Phys. Rev. B 92, 020402(R) (2015); Selzer et al., Phys. Rev. Lett. 117, 107201 (2016)], but more importantly gives the concrete conditions under which these conclusions apply, respectively. Our results may provide useful information on the antiferromagnetic spintronics for future experiments and storage device design.Comment: 6 pages, 7 figures, published in Physical Review

High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode

We present an approach for the highly sensitive photon detection based on the quantum dots (QDs) operating at temperature of 77K. The detection structure is based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons per second had induced 10nA photocurrent in this structure, corresponding to the photo-excited carrier multiplication factor of 10^7. This high multiplication factor is achieved by the quantum dot induced memory effect and the resonant tunneling tuning effect of QD-RTD structure.Comment: 10 pages,5 figures. Submitted to Applied Physics Letter

Tunable and absolute electromagnetic vacuum in two-dimensional photonic-band-gap Based on multiferroic materials

When multiferroic terbium manganite (TbMnO₃) crystal cylinders are periodically arranged in a square lattice, the resulting two-dimensional (2D) system exhibits photonic band gaps (PBGs). The absolute PBG originating from the Mie resonance is modulated from closed to open by applying an external static magnetic field, which is attributed to the electromagnon depression of the dielectric constant by the rearrangement of antiferromagnetic order. Tunable electromagnetic band structure may be realized by controlling the magnetic transition of manganese spins in TbMnO₃.The authors are grateful for financial support from the Outstanding Foundation of NJUST, the NJUST Research Funding (No. 2010ZDJH06), the National Natural Science Foundation of China (Grant Nos. 11004106, 50672034, 50832002, and 50901042), and the State Key Program for Basic Research of China (Grant Nos. 2009CB623303 and 2009CB929501)

Synthesis of tributyl citrate using SO42-/Zr-MCM-41 as catalyst

Zirconium-containing mesoporous molecular sieve SO42-/Zr-MCM-41 was synthesized for catalyst in synthesis of tributyl citrate. The structure was characterized by XRD, N2 Ad/De isotherms and FT-IR. The results indicated that the solid acids show good catalytic performance and are reusable. Under optimum conditions and using SO42-/Zr-MCM-41 as catalyst, the conversion of citric acid was 95%. After easy separation of the products from the solid acid catalyst, it could be reused three times and gave a conversion of citric acid not less than 92%. The structure of tributyl citrate was characterized by FT-IR and 1H-NMR.KEY WORDS: Mesoporous molecular sieve, Tributyl citrate, Synthesis Bull. Chem. Soc. Ethiop. 2011, 25(1), 147-150

A non-tight junction function of claudin-7—Interaction with integrin signaling in suppressing lung cancer cell proliferation and detachment

Background Claudins are a family of tight junction (TJ) membrane proteins involved in a broad spectrum of human diseases including cancer. Claudin-7 is a unique TJ membrane protein in that it has a strong basolateral membrane distribution in epithelial cells and in tissues. Therefore, this study aims to investigate the functional significance of this non-TJ localization of claudin-7 in human lung cancer cells. Methods Claudin-7 expression was suppressed or deleted by lentivirus shRNA or by targeted-gene deletion. Cell cycle analysis and antibody blocking methods were employed to assay cell proliferation and cell attachment, respectively. Electron microscopy and transepthelial electrical resistance measurement were performed to examine the TJ ultrastructure and barrier function. Co-immunolocalization and co-immunoprecipitation was used to study claudin-7 interaction with integrin β1. Tumor growth in vivo were analyzed using athymic nude mice. Results Claudin-7 co-localizes and forms a stable complex with integrin β1. Both suppressing claudin-7 expression by lentivirus shRNA in human lung cancer cells (KD cells) and deletion of claudin-7 in mouse lungs lead to the reduction in integrin β1 and phospho-FAK levels. Suppressing claudin-7 expression increases cell growth and cell cycle progression. More significantly, claudin-7 KD cells have severe defects in cell-matrix interactions and adhere poorly to culture plates with a remarkably reduced integrin β1 expression. When cultured on uncoated glass coverslips, claudin-7 KD cells grow on top of each other and form spheroids while the control cells adhere well and grow as a monolayer. Reintroducing claudin-7 reduces cell proliferation, upregulates integrin β1 expression and increases cell-matrix adhesion. Integrin β1 transfection partially rescues the cell attachment defect. When inoculated into nude mice, claudin-7 KD cells produced significantly larger tumors than control cells. Conclusion In this study, we identified a previously unrecognized function of claudin-7 in regulating cell proliferation and maintaining epithelial cell attachment through engaging integrin β1

Graph Learning of Multifaceted Motivations for Online Engagement Prediction in Counter-party Social Networks

Social media has emerged as an essential venue to invigorate online political engagement. However, political engagement is multifaceted and impacted by both individuals\u27 self-motivation and social influence from peers and remains challenging to model in a counter-party network. Therefore, we propose a counter-party graph representation learning model to study individuals\u27 intrinsic and extrinsic motivations for online political engagement. Firstly, we capture users\u27 intrinsic political interests providing self-motivation from a user-topic network. Then, we encode how users cast influence on others from the inner-/counter-party through a user-user network. With the learned embedding of intrinsic and extrinsic motivations, we model the interactions between these two facets and utilize the dependency by deep sequential model decoding. Finally, extensive experiments using Twitter data related to the 2020 U.S. presidential election and the 2019 HK protests validate the model\u27s predictive power. This study has implications for online political engagement, political participation, and political polarization

Sensation Seeking, Deviant Peer Affiliation, and Internet Gaming Addiction Among Chinese Adolescents: The Moderating Effect of Parental Knowledge

Although there is abundant evidence that an association between sensation seeking and adolescent Internet gaming addiction (IGA) exists, research has provided little insight into why adolescents with high sensation seeking are more likely to be focused on Internet and video games. Grounded in the social development model and ecological systems theory, this study investigated whether deviant peer affiliation mediated the relationship between sensation seeking and adolescent IGA, and whether this indirect link was moderated by parental knowledge. Participants were 1293 Chinese adolescents (49.65% male, Mage = 12.89 ± 0.52 years) who completed questionnaires assessing sensation seeking, deviant peer affiliation, parental knowledge, and IGA. Structural equation models revealed that the positive association between sensation seeking and adolescent IGA was partially mediated by deviant peer affiliation. In addition, this indirect link was significantly moderated by parental knowledge. Specifically, the indirect path from sensation seeking to adolescent IGA was stronger for adolescents with low parental knowledge than for those with high parental knowledge. Identifying the role of peers and parents in the onset of adolescent IGA has key implications for prevention and intervention

Asynchronous Verifiable Secret Sharing with Elastic Thresholds and Distributed Key Generation

Distributed Key Generation (DKG) is a technique that enables the generation of threshold cryptography keys among a set of mutually untrusting nodes. DKG generates keys for a range of decentralized applications such as threshold signatures, multiparty computation, and Byzantine consensus. Over the past five years, research on DKG has focused on optimizing network communication protocols to improve overall system efficiency by reducing communication complexity. However, SOTA asynchronous distributed key generation (ADKG) schemes (e.g., Kokoris-Kogias ADKG, CCS 2020 and Das ADKG, S\&P 2022, and others) only support recovery thresholds of either $f$ or $2f$, where $f$ is the maximum number of malicious nodes. This paper proposes an asynchronous verifiable secret sharing protocol featuring an elastic threshold, where $t \in [f,n-f-1]$ and $n \ge 3f+1$ is the total number of parties. Our protocol enables a dealer to share up to $t+1$ secrets with a total communication cost of O($\lambda n^3$), where $\lambda$ is the security parameter, and the protocol relies on the hardness of the $q$-SDH problem. We further modified the Schnorr protocol to enable simultaneous commitments to multiple secrets, which we refer to $m$-Schnorr