Essential L-Amino Acid-Functionalized Graphene Oxide for Liquid Crystalline Phase Formation

The colloidal 2D materials based on graphene and its modifications are of great interest when it comes to forming LC phases. These LC phases allow controlling the orientational order of colloidal particles, paving the way for the efficient processing of modified graphene with anisotropic properties. Here, we present the peculiarities of AA functionalization of GO, along with the formation of its LC phase and orientational behavior in an external magnetic field. We discuss the influence of pH on the GOLC, ultimately showing its pH-dependent behavior for GO-AA complexes. In addition, we observe different GO morphology changes due to the presence of AA functional groups, namely L-cysteine dimerization on the GO platform. The pH dependency of AA-functionalized LC phase of GO is examined for the first time. We believe that our studies will open new possibilities for applications in bionanotechnologies due to self-assembling properties of LCs and magnificent properties of GO.Comment: 10 pages, 16 figure

Low temperature vortex liquid in La2−xSrxCuO4\rm La_{2-x}Sr_xCuO_4

In the cuprates, the lightly-doped region is of major interest because superconductivity, antiferromagnetism, and the pseudogap state \cite{Timusk,Lee,Anderson} come together near a critical doping value $x_c$. These states are deeply influenced by phase fluctuations \cite{Emery} which lead to a vortex-liquid state that surrounds the superconducting region \cite{WangPRB01,WangPRB06}. However, many questions \cite{Doniach,Fisher,FisherLee,Tesanovic,Sachdev} related to the nature of the transition and vortex-liquid state at very low tempera- tures $T$ remain open because the diamagnetic signal is difficult to resolve in this region. Here, we report torque magnetometry results on $\rm La_{2-x}Sr_xCuO_4$ (LSCO) which show that superconductivity is lost at $x_c$ by quantum phase fluctuations. We find that, in a magnetic field $H$, the vortex solid-to-liquid transition occurs at field $H_m$ much lower than the depairing field $H_{c2}$. The vortex liquid exists in the large field interval $H_m \ll H_{c2}$, even in the limit $T\to$0. The resulting phase diagram reveals the large fraction of the $x$-$H$ plane occupied by the quantum vortex liquid.Comment: 6 pages, 4 figures, submitted to Nature Physic

Silicon-Organic Hybrid (SOH) and Plasmonic-Organic Hybrid (POH) integration

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, nei-ther silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonic-organic hybrid integration, which combine SOI waveguides and plasmonic nanostructures with organic electro-optic cladding materials

High speed plasmonic modulator array enabling dense optical interconnect solutions

Plasmonic modulators might pave the way for a new generation of compact low-power high-speed optoelectronic devices. We introduce an extremely compact transmitter based on plasmonic Mach-Zehnder modulators offering a capacity of 4 × 36 Gbit/s on a footprint that is only limited by the size of the high-speed contact pads. The transmitter array is contacted through a multicore fiber with a channel spacing of 50 μm

Silicon-plasmonic internal-photoemission detector for 40 Gbit/s data reception

Silicon-plasmonics enables the fabrication of active photonic circuits in CMOS technology with unprecedented operation speed and integration density. Regarding applications in chip-level optical interconnects, fast and efficient plasmonic photodetectors with ultrasmall footprints are of special interest. A particularly promising approach to silicon-plasmonic photodetection is based on internal photoemission (IPE), which exploits intrinsic absorption in plasmonic waveguides at the metal–dielectric interface. However, while IPE plasmonic photodetectors have already been demonstrated, their performance is still far below that of conventional high-speed photodiodes. In this paper, we demonstrate a novel class of IPE devices with performance parameters comparable to those of state-of-the-art photodiodes while maintaining footprints below 1  μm 2 . The structures are based on asymmetric metal–semiconductor–metal waveguides with a width of less than 75 nm. We measure record-high sensitivities of up to 0.12 A/W at a wavelength of 1550 nm. The detectors exhibit opto-electronic bandwidths of at least 40 GHz. We demonstrate reception of on–off keying data at rates of 40 Gbit/s

Nanophotonic modulators and photodetectors using silicon photonic and plasmonic device concepts

Nanophotonic modulators and photodetectors are key building blocks for high-speed optical interconnects in datacom and telecom networks. Besides power efficiency and high electro-optic bandwidth, ultra-compact footprint and scalable co-integration with electronic circuitry are indispensable for highly scalable communication systems. In this paper, we give an overview on our recent progress in exploring nanophotonic modulators and photodetectors that combine the specific strengths of silicon photonic and plasmonic device concepts with hybrid integration approaches. Our work comprises electro-optic modulators that exploit silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) integration to enable unprecedented energy efficiency and transmission speed, as well as waveguide-based plasmonic internal photo-emission detectors (PIPED) with record-high sensitivities and bandwidths

Quantum oscillations from Fermi arcs

When a metal is subjected to strong magnetic field B nearly all measurable quantities exhibit oscillations periodic in 1/B. Such quantum oscillations represent a canonical probe of the defining aspect of a metal, its Fermi surface (FS). In this study we establish a new mechanism for quantum oscillations which requires only finite segments of a FS to exist. Oscillations periodic in 1/B occur if the FS segments are terminated by a pairing gap. Our results reconcile the recent breakthrough experiments showing quantum oscillations in a cuprate superconductor YBCO, with a well-established result of many angle resolved photoemission (ARPES) studies which consistently indicate "Fermi arcs" -- truncated segments of a Fermi surface -- in the normal state of the cuprates.Comment: 8 pages, 5 figure

A Compensatory Mutation Provides Resistance to Disparate HIV Fusion Inhibitor Peptides and Enhances Membrane Fusion

Fusion inhibitors are a class of antiretroviral drugs used to prevent entry of HIV into host cells. Many of the fusion inhibitors being developed, including the drug enfuvirtide, are peptides designed to competitively inhibit the viral fusion protein gp41. With the emergence of drug resistance, there is an increased need for effective and unique alternatives within this class of antivirals. One such alternative is a class of cyclic, cationic, antimicrobial peptides known as θ-defensins, which are produced by many non-human primates and exhibit broad-spectrum antiviral and antibacterial activity. Currently, the θ-defensin analog RC-101 is being developed as a microbicide due to its specific antiviral activity, lack of toxicity to cells and tissues, and safety in animals. Understanding potential RC-101 resistance, and how resistance to other fusion inhibitors affects RC-101 susceptibility, is critical for future development. In previous studies, we identified a mutant, R5-tropic virus that had evolved partial resistance to RC-101 during in vitro selection. Here, we report that a secondary mutation in gp41 was found to restore replicative fitness, membrane fusion, and the rate of viral entry, which were compromised by an initial mutation providing partial RC-101 resistance. Interestingly, we show that RC-101 is effective against two enfuvirtide-resistant mutants, demonstrating the clinical importance of RC-101 as a unique fusion inhibitor. These findings both expand our understanding of HIV drug-resistance to diverse peptide fusion inhibitors and emphasize the significance of compensatory gp41 mutations. © 2013 Wood et al

Quasiparticle Hall Transport of d-wave Superconductors in Vortex State

We present a theory of quasiparticle Hall transport in strongly type-II superconductors within their vortex state. We establish the existence of integer quantum spin Hall effect in clean unconventional $d_{x^2-y^2}$ superconductors in the vortex state from a general analysis of the Bogoliubov-de Gennes equation. The spin Hall conductivity $\sigma^s_{xy}$ is shown to be quantized in units of $\frac{\hbar}{8\pi}$. This result does not rest on linearization of the BdG equations around Dirac nodes and therefore includes inter-nodal physics in its entirety. In addition, this result holds for a generic inversion-symmetric lattice of vortices as long as the magnetic field $B$ satisfies $H_{c1} \ll B \ll H_{c2}$. We then derive the Wiedemann-Franz law for the spin and thermal Hall conductivity in the vortex state. In the limit of $T \to 0$, the thermal Hall conductivity satisfies $\kappa_{x y}=\frac{4\pi^2}{3}(\frac{k_B}{\hbar})^2 T \sigma^s_{xy}$. The transitions between different quantized values of $\sigma^s_{xy}$ as well as relation to conventional superconductors are discussed.Comment: 18 pages REVTex, 3 figures, references adde

Comparative experimental evaluation of the efficiency of the application different methods of treatment chronic parodontitis.

“Metrogil Denta” is more effective for the treatment of experimental parodontitis then fibroblasts.Использование геля «Метрогил Дента» для снижения активности воспалительного процесса при экспериментальном пародонтите более эффективно, чем введение фибробластов