Multiferroic hexagonal ferrites (h-RFeO3_3, R=Y, Dy-Lu): an experimental review

Hexagonal ferrites (h-RFeO$_3$, R=Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO$_3$ rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature multiferroicity and predicted magnetoelectric effect, h-RFeO$_3$ are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic, and magnetoelectric properties of h-RFeO$_3$. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties

Multiferroic hexagonal ferrites (h-RFeO3, R=Y, Dy-Lu): an experimental review

Hexagonal ferrites (h-RFeO3, R=Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO3 rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature mul- tiferroicity and predicted magnetoelectric effect, h-RFeO3 are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic, and magnetoelectric properties of h-RFeO3. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties

On Bergman kernel functions and weak Morse inequalities

We give simple and unified proofs of weak holomorhpic Morse inequalities on complete manifolds, $q$-convex manifolds, pseudoconvex domains, weakly $1$-complete manifolds and covering manifolds. This paper is essentially based on the asymptotic Bergman kernel functions and the Bochner-Kodaira-Nakano formulas

A Filled Function Method Dominated by Filter for Nonlinearly Global Optimization

This work presents a filled function method based on the filter technique for global optimization. Filled function method is one of the effective methods for nonlinear global optimization, since it can effectively find a better minimizer. Filter technique is applied to local optimization methods for its excellent numerical results. In order to optimize the filled function method, the filter method is employed for global optimizations in this method. A new filled function is proposed first, and then the algorithm and its properties are proved. The numerical results are listed at the end

The Nitrilimine-Alkene Cycloaddition Mechanism and Phage-displayed Cyclic Peptide Libraries for Drug Discovery

This study is composed of two parts. In the first part, we discussed nitrilimine-alkene cycloaddition for protein labeling. The mechanism of this nitrilimine-alkene cycloaddition was proposed, and thereby the best experimental condition for this protein labeling approach was investigated. The transient formation of nitrilimine in aqueous conditions is greatly influenced by pH and chloride. In basic conditions (pH 10) with no chloride, a diarylnitrilimine precursor readily ionizes to form diarylnitrilimine that reacts almost instantly with an acrylamide-containing protein and fluorescently labels it. In the second part, a novel method for the synthesis of phage-displayed cyclic peptide libraries is presented. Cyclic peptide drugs are appealing in the drug discovery research area due to their unique advantages including high affinity, high specificity, low toxicity, and high cellular and serum stability. In order to identify cyclic peptides as therapeutic agents, during my graduate study I have developed a phage display-based methodology that integrates the genetic noncanonical amino acid (ncAA) mutagenesis technique for the synthesis of novel phage-displayed cyclic peptides through simultaneous 1,4-addition between a cysteine thiol group and acrylamide moiety in Nε -acryloyl-lysine (AcrK), a ncAA. Both cysteine and AcrK are genetically coded. The success of using a cysteine and an AcrK to cyclic a peptide in a model protein and phages was validated by various approaches. In order to afford a library, a phage-displayed cyclic peptide library was constructed by inserting a consecutive but sequence-randomized 6-mer peptide flanked by an amino side cysteine and a carboxyl side AcrK. Panning of the synthesized phage-displayed cyclic peptide library was performed against two target proteins that are tobacco etch virus (TEV) protease and histone deacetylase 8 (HDAC8). A lot of high-affinity phage clones were isolated and collected. DNA sequencing of these selected clones led to the identification of several peptides that potentially inhibit TEV protease and HDAC8. To confirm their potencies as inhibitors, abundant peptides and their fluorophore-conjugated derivatives were synthesized through solid-phase peptide synthesis (SPPS). Measurements of fluorescence polarization change and IC50 value of these peptides when they bound to TEV protease and HDAC8 were performed. Overall, we have mechanistically characterized the nitrilimine-alkene cycloaddition reaction and developed a novel approach for the synthesis of phage-displayed cyclic peptide libraries. The selection of displayed peptides against TEV protease and HDAC8 has resulted in multiple peptides that display high potencies against these two enzymes

Tuning the Magnetic Ordering Temperature of Hexagonal Ferrites by Structural Distortion Control

To tune the magnetic properties of hexagonal ferrites, a family of magnetoelectric multiferroic materials, by atomic-scale structural engineering, we studied the effect of structural distortion on the magnetic ordering temperature (TN). Using the symmetry analysis, we show that unlike most antiferromagnetic rare-earth transition-metal perovskites, a larger structural distortion leads to a higher TN in hexagonal ferrites and manganites, because the K3 structural distortion induces the three-dimensional magnetic ordering, which is forbidden in the undistorted structure by symmetry. We also revealed a near-linear relation between TN and the tolerance factor and a power-law relation between TN and the K3 distortion amplitude. Following the analysis, a record-high TN (185 K) among hexagonal ferrites was predicted in hexagonal ScFeO3 and experimentally verified in epitaxially stabilized films. These results add to the paradigm of spin-lattice coupling in antiferromagnetic oxides and suggests further tunability of hexagonal ferrites if more lattice distortion can be achieved

SgVA-CLIP: Semantic-guided Visual Adapting of Vision-Language Models for Few-shot Image Classification

Although significant progress has been made in few-shot learning, most of existing few-shot image classification methods require supervised pre-training on a large amount of samples of base classes, which limits their generalization ability in real world application. Recently, large-scale Vision-Language Pre-trained models (VLPs) have been gaining increasing attention in few-shot learning because they can provide a new paradigm for transferable visual representation learning with easily available text on the Web. However, the VLPs may neglect detailed visual information that is difficult to describe by language sentences, but important for learning an effective classifier to distinguish different images. To address the above problem, we propose a new framework, named Semantic-guided Visual Adapting (SgVA), which can effectively extend vision-language pre-trained models to produce discriminative adapted visual features by comprehensively using an implicit knowledge distillation, a vision-specific contrastive loss, and a cross-modal contrastive loss. The implicit knowledge distillation is designed to transfer the fine-grained cross-modal knowledge to guide the updating of the vision adapter. State-of-the-art results on 13 datasets demonstrate that the adapted visual features can well complement the cross-modal features to improve few-shot image classification