Surface functionalized substrates and their interactions with biomolecules and cells

Ph.DDOCTOR OF PHILOSOPH

An unambiguous test of positivity at lepton colliders

The diphoton channel at lepton colliders, $e^+e^- (\mu^+\mu^-) \to \gamma \gamma$, has a remarkable feature that the leading new physics contribution comes only from dimension-eight operators. This contribution is subject to a set of positivity bounds, derived from fundamental principles of Quantum Field Theory, such as unitarity, locality and analyticity. These positivity bounds are thus applicable to the most direct observable -- the diphoton cross sections. This unique feature provides a clear, robust, and unambiguous test of these principles. We estimate the capability of various future lepton colliders in probing the dimension-eight operators and testing the positivity bounds in this channel. We show that positivity bounds can lift certain degeneracies among the effective operators and significantly change the perspectives of a global analysis. We also perform a combined analysis of the $\gamma\gamma/Z\gamma/ZZ$ processes in the high energy limit and point out the important interplay among them.Comment: 6 pages, 4 figure

Light induced non-volatile switching of superconductivity in single layer FeSe on SrTiO3 substrate

The capability of controlling superconductivity by light is highly desirable for active quantum device applications. Since superconductors rarely exhibit strong photoresponses, and optically sensitive materials are often not superconducting, efficient coupling between these two characters can be very challenging in a single material. Here we show that, in FeSe/SrTiO3 heterostructures, the superconducting transition temperature in FeSe monolayer can be effectively raised by the interband photoexcitations in the SrTiO3substrate. Attributed to a light induced metastable polar distortion uniquely enabled by the FeSe/SrTiO3 interface, this effect only requires a less than 50 µW cm−2 continuous-wave light field. The fast optical generation of superconducting zero resistance state is non-volatile but can be rapidly reversed by applying voltage pulses to the back of SrTiO3substrate. The capability of switching FeSe repeatedly and reliably between normal and superconducting states demonstrate the great potential of making energy-efficient quantum optoelectronics at designed correlated interfaces

Tetra­aqua­bis(2-methyl­benzimidazolium-1,3-diacetato-κO)zinc(II) tetra­hydrate

The asymmetric unit of the title compound, [Zn(C12H11N2O4)2(H2O)4]·4H2O, contains one-half of the complex mol­ecule and two uncoordin­ated water mol­ecules. The four water O atoms in the equatorial plane around the ZnII centre ( symmetry) form a distorted square-planar arrangement, while the distorted octa­hedral coordination geometry is completed by the O atoms of the zwitterionic 2-methyl­benzimidazolium-1,3-diacetate ligands in the axial positions. The benzimidazole ring system is planar, with a maximum deviation of 0.041 (3) Å. Intra­molecular O—H⋯O hydrogen bonding results in the formation of a non-planar six-membered ring. In the crystal structure, strong intra- and inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. π–π contacts between benzimidazole rings [centroid–centroid distance = 3.899 (1) Å] may further stabilize the structure

An injectable scaffold based on crosslinked hyaluronic acid gel for tissue regeneration

An injectable scaffold of crosslinked hyaluronic acid gel for tissue regeneration.</p

Preparative Scale Production of Functional Mouse Aquaporin 4 Using Different Cell-Free Expression Modes

The continuous progress in the structural and functional characterization of aquaporins increasingly attracts attention to study their roles in certain mammalian diseases. Although several structures of aquaporins have already been solved by crystallization, the challenge of producing sufficient amounts of functional proteins still remains. CF (cell free) expression has emerged in recent times as a promising alternative option in order to synthesize large quantities of membrane proteins, and the focus of this report was to evaluate the potential of this technique for the production of eukaryotic aquaporins. We have selected the mouse aquaporin 4 as a representative of mammalian aquaporins. The protein was synthesized in an E. coli extract based cell-free system with two different expression modes, and the efficiencies of two modes were compared. In both, the P-CF (cell-free membrane protein expression as precipitate) mode generating initial aquaporin precipitates as well as in the D-CF (cell-free membrane protein expression in presence of detergent) mode, generating directly detergent solubilized samples, we were able to obtain mg amounts of protein per ml of cell-free reaction. Purified aquaporin samples solubilized in different detergents were reconstituted into liposomes, and analyzed for the water channel activity. The calculated Pf value of proteoliposome samples isolated from the D-CF mode was 133 µm/s at 10°C, which was 5 times higher as that of the control. A reversible inhibitory effect of mercury chloride was observed, which is consistent with previous observations of in vitro reconstituted aquaporin 4. In this study, a fast and convenient protocol was established for functional expression of aquaporins, which could serve as basis for further applications such as water filtration

The Release of Nitric Oxide Is Involved in the β-Arrestin1-Induced Antihypertensive Effect in the Rostral Ventrolateral Medulla

β-Arrestin1 is a multifunctional scaffold protein with the ability to interact with diverse signaling molecules independent of G protein-coupled receptors. We previously reported that overexpression of β-arrestin1 in the rostral ventrolateral medulla (RVLM) decreased blood pressure (BP) and renal sympathetic nerve activity (RSNA) in spontaneously hypertensive rats (SHRs). Nitric oxide (NO) is widely reported to be involved in central cardiovascular regulation. The goal of this study was to investigate whether NO signaling contributes to the β-arrestin1-mediated antihypertensive effect in the RVLM. It was found that bilateral injection of adeno-associated virus containing Arrb1 gene (AAV-Arrb1) into the RVLM of SHRs significantly increased NO production and NO synthase (NOS) activity. Microinjection of the non-selective NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME; 10 nmol) into the RVLM prevented the β-arrestin1-induced cardiovascular inhibitory effect. Furthermore, β-arrestin1 overexpression in the RVLM significantly upregulated the expression of phosphorylated neuronal NOS (nNOS) by 3.8-fold and extracellular regulated kinase 1/2 (ERK1/2) by 5.6-fold in SHRs. The β-arrestin1-induced decrease in BP and RSNA was significantly abolished by treatment with ERK1/2 small interfering RNA (ERK1/2 siRNA). Moreover, ERK1/2 siRNA attenuated the β-arrestin1-induced NO production, NOS activity, and nNOS phosphorylation in the RVLM. Taken together, these data demonstrate that the antihypertensive effect of β-arrestin1 in the RVLM is mediated by nNOS-derived NO release, which is associated with ERK1/2 activation

Room-temperature ferromagnetism in epitaxial bilayer FeSb/SrTiO3(001) terminated with a Kagome lattice

Two-dimensional (2D) magnets exhibit unique physical properties for potential applications in spintronics. To date, most 2D ferromagnets are obtained by mechanical exfoliation of bulk materials with van der Waals interlayer interactions, and the synthesis of single or few-layer 2D ferromagnets with strong interlayer coupling remains experimentally challenging. Here, we report the epitaxial growth of 2D non-van der Waals ferromagnetic bilayer FeSb on SrTiO3(001) substrates stabilized by strong coupling to the substrate, which exhibits in-plane magnetic anisotropy and a Curie temperature above 300 K. In-situ low-temperature scanning tunneling microscopy/spectroscopy and density-functional theory calculations further reveal that a Fe Kagome layer terminates the bilayer FeSb. Our results open a new avenue for further exploring emergent quantum phenomena from the interplay of ferromagnetism and topology for application in spintronics

Fabrication and Characterization of Collagen/PVA Dual-Layer Membranes for Periodontal Bone Regeneration

Guided tissue regeneration (GTR) is a promising treatment for periodontal tissue defects, which generally uses a membrane to build a mechanical barrier from the gingival epithelium and hold space for the periodontal regeneration especially the tooth-supporting bone. However, existing membranes possess insufficient mechanical properties and limited bioactivity for periodontal bone regenerate. Herein, fish collagen and polyvinyl alcohol (Col/PVA) dual-layer membrane were developed via a combined freezing/thawing and layer coating method. This dual-layer membrane had a clear but contact boundary line between collagen and PVA layers, which were both hydrophilic. The dual membrane had an elongation at break of 193 ± 27% and would undergo an in vitro degradation duration of more than 17 days. Further cell experiments showed that compared with the PVA layer, the collagen layer not only presented good cytocompatibility with rat bone marrow-derived mesenchymal stem cells (BMSCs), but also promoted the osteogenic genes (RUNX2, ALP, OCN, and COL1) and protein (ALP) expression of BMSCs. Hence, the currently developed dual-layer membranes could be used as a stable barrier with a stable degradation rate and selectively favor the bone tissue to repopulate the periodontal defect. The membranes could meet the challenges encountered by GTR for superior defect repair, demonstrating great potential in clinical applications