Correlative iPALM and SEM resolves virus cavity and Gag lattice defects in HIV virions.

Interferometric Photo-Activation-Localization-Microscopy (iPALM) localizes single fluorescent molecules with 20 nm lateral and 10 nm axial resolution. We present a method utilizing glass coverslip lithography for correlative imaging between iPALM and scanning electron microscopy (SEM). Using iPALM on HIV Gag-Dendra virus-like particles (VLPs) we localized the position of HIV Gag proteins. Based on these localizations we reconstructed the central cavity of the VLPs along with imperfections within the HIV Gag lattice. The SEM images and iPALM images overlap and show imaging from single VLPs immobilized on glass coverslips. The localization of many HIV proteins including accessory proteins and Gag-Pol remains unknown, we discuss how the specificity of iPALM coupled with SEM has the potential for resolving more of HIV proteins.

Freestanding Organic Charge-Transfer Conformal Electronics.

Wearable conformal electronics are essential components for next-generation humanlike sensing devices that can accurately respond to external stimuli in nonplanar and dynamic surfaces. However, to explore this potential, it is indispensable to achieve the desired level of deformability and charge-transport mobility in strain-accommodating soft semiconductors. Here, we show pseudo-two-dimensional freestanding conjugated polymer heterojunction nanosheets integrated into substrate-free conformal electronics owing to their exceptional crystalline controlled charge transport and high level of mechanical strength. These freestanding and mechanical robust polymer nanosheets can be adapted into a variety of artificial structured surfaces such as fibers, squares, circles, etc., which produce large-area stretchable conformal charge-transfer sensors for real-time static and dynamic monitoring.

Isotropic Effective Spin-Orbit Coupling in a Conjugated Polymer.

Conjugated polymers are anisotropic in shape and with regard to electronic properties. Little is known as to how electronic anisotropy impacts the underlying characteristics of the electron spin, such as the coupling to orbital magnetic moments. Using multifrequency electrically detected magnetic resonance spectroscopy extending over 12 octaves in frequency, we explore the effect of spin-orbit coupling by examining the pronounced broadening of resonance spectra with increasing magnetic field. Whereas in three commonly used materials, the high-field spectra show asymmetric broadening, as would be expected from anisotropic g-strain effects associated with the molecular structure, in the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) the spectra broaden isotropically, providing a direct measure of the microscopic distribution in g-factors. This observation implies that effective charge-carrier g-tensors are isotropic, which likely originates from motional narrowing in this high-mobility material.

Organic-based magnon spintronics.

Magnonics concepts utilize spin-wave quanta (magnons) for information transmission, processing and storage. To convert information carried by magnons into an electric signal promises compatibility of magnonic devices with conventional electronic devices, that is, magnon spintronics 1 . Magnons in inorganic materials have been studied widely with respect to their generation2,3, transport4,5 and detection 6 . In contrast, resonant spin waves in the room-temperature organic-based ferrimagnet vanadium tetracyanoethylene (V(TCNE) x (x ≈ 2)), were detected only recently 7 . Herein we report room-temperature coherent magnon generation, transport and detection in films and devices based on V(TCNE) x using three different techniques, which include broadband ferromagnetic resonance (FMR), Brillouin light scattering (BLS) and spin pumping into a Pt adjacent layer. V(TCNE) x can be grown as neat films on a large variety of substrates, and it exhibits extremely low Gilbert damping comparable to that in yttrium iron garnet. Our studies establish an alternative use for organic-based magnets, which, because of their synthetic versatility, may substantially enrich the field of magnon spintronics.

Monolithic OLED-Microwire Devices for Ultrastrong Magnetic Resonant Excitation.

Organic light-emitting diodes (OLEDs) make highly sensitive probes to test magnetic resonance phenomena under unconventional conditions since spin precession controls singlet-triplet transitions of electron-hole pairs, which in turn give rise to distinct recombination currents in conductivity. Electron paramagnetic resonance can therefore be detected in the absence of spin polarization. We exploit this characteristic to explore the exotic regime of ultrastrong light-matter coupling, where the Rabi frequency of a charge carrier spin is of the order of the transition frequency of the two-level system. To reach this domain, we have to lower the Zeeman splitting of the spin states, defined by the static magnetic field B0, and raise the strength of the oscillatory driving field of the resonance, B1. This is achieved by shrinking the OLED and bringing the source of resonant radio frequency (RF) radiation as close as possible to the organic semiconductor in a monolithic device structure, which incorporates an OLED fabricated directly on top of an RF microwire within one monolithic thin-film device structure. With an RF driving power in the milliwatt range applied to the microwire, the regime of bleaching and inversion of the magnetic resonance signal is reached due to the onset of the spin-Dicke effect. In this example of ultrastrong light-matter coupling, the individual resonant spin transitions of electron-hole pairs become indistinguishable with respect to the driving field, and superradiance of the magnetic dipole transitions sets in.

The c.-190 C>A transversion in promoter region of protamine1 gene as a genetic risk factor for idiopathic oligozoospermia.

The genome condensation in the sperm head is resulted with replacing of histones by protamines during spermatogenesis. It is reported that defects in the protamine 1 (PRM1) and/or 2 (PRM2) genes cause male infertility. Located on chromosome 16 (16p13.2) these genes contain numerous unstudied single nucleotide polymorphisms. This study aimed to investigate the association of c.-190 C>A and g.298 G>C transversions that respectively occur in PRM1 and PRM2 genes with idiopathic oligozoospermia. In a case-control study, we collected blood samples from 130 idiopathic oligozoospermia and 130 fertile men. Detection of c.-190 C>A and g.298 G>C polymorphisms performed by direct sequencing and PCR-RFLP methods respectively. An in silico analysis was performed by ASSP, NetGene 2, and PNImodeler online web servers. Our data revealed that g.298 G>C transversion in PRM2 was not associated with oligozoospermia (P > 0.05). Whereas, -190CA and -190AA genotypes in PRM1 gene were associated significantly with increased risk of oligozoospermia (P = 0.0017 and 0.0103, respectively). Also carriers of A allele (CA+AA) for PRM1 c.-190 C>A were at a high risk for oligozoospermia (OR 3.2440, 95 % CI 1.8060-5.8270, P = 0.0001). Further, in silico analysis revealed that c.-190 C>A transversion may alter transcription factor interactions with the promoter region of PRM1. The results revealed that the c.-190 C>A transversion may involve in the susceptibility for oligozoospermia and could be represented as a noninvasive molecular marker for genetic diagnosis of idiopathic oligozoospermia.

Superconductor-insulator transition in long MoGe nanowires.

The properties of one-dimensional superconducting wires depend on physical processes with different characteristic lengths. To identify the process dominant in the critical regime we have studied the transport properties of very narrow (9-20 nm) MoGe wires fabricated by advanced electron-beam lithography in a wide range of lengths, 1-25 µm. We observed that the wires undergo a superconductor-insulator transition (SIT) that is controlled by cross sectional area of a wire and possibly also by the width-to-thickness ratio. The mean-field critical temperature decreases exponentially with the inverse of the wire cross section. We observed that a qualitatively similar superconductor-insulator transition can be induced by an external magnetic field. Our results are not consistent with any currently known theory of the SIT. Some long superconducting MoGe nanowires can be identified as localized superconductors; namely, in these wires the one-electron localization length is much smaller than the length of a wire.