C-projective geometry

We develop in detail the theory of (almost) c-projective geometry, a natural analogue of projective differential geometry adapted to (almost) complex manifolds. We realise it as a type of parabolic geometry and describe the associated Cartan or tractor connection. A Kähler manifold gives rise to a c-projective structure and this is one of the primary motivations for its study. The existence of two or more Kähler metrics underlying a given c-projective structure has many ramifications, which we explore in depth. As a consequence of this analysis, we prove the Yano- Obata Conjecture for complete Kähler manifolds: if such a manifold admits a one parameter group of c-projective transformations that are not affine, then it is complex projective space, equipped with a multiple of the Fubini-Study metric.</p

C-projective geometry

We develop in detail the theory of (almost) c-projective geometry, a natural analogue of projective differential geometry adapted to (almost) complex manifolds. We realise it as a type of parabolic geometry and describe the associated Cartan or tractor connection. A Kähler manifold gives rise to a c-projective structure and this is one of the primary motivations for its study. The existence of two or more Kähler metrics underlying a given c-projective structure has many ramifications, which we explore in depth. As a consequence of this analysis, we prove the Yano- Obata Conjecture for complete Kähler manifolds: if such a manifold admits a one parameter group of c-projective transformations that are not affine, then it is complex projective space, equipped with a multiple of the Fubini-Study metric.</p

Novel push-pull chromophores to prepare electro-optic modulators

In recent years, a large number of push-pull organic molecules have been proposed as promising candidates for electronic and optical applications. Generally, the main effort has been focused on the design of chromophores with large first hyperpolarizability values (β); this would result in a wide variety of nonlinear optical (NLO) applications, such as modulators.[1,2] In this work, we report an experimental and theoretical investigation of the NLO properties of novel push-pull systems derived from the dicyanomethylene-4H-chromene (DCM) group. Particular attention will be paid to better understand the molecular and electronic properties of these systems by using vibrational spectroscopic techniques and electrochemistry. Furthermore, these materials have been tested in a silicon-organic hybrid modulator based on an integrated dual-mode interferometer.[3]Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Charge‐Compensated N‐Doped π ‐Conjugated Polymers: Toward both Thermodynamic Stability of N‐Doped States in Water and High Electron Conductivity

The understanding and applications of electron-conducting π-conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n-doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n-doped backbone. Here, the n-type conducting NDI polymer with enhanced stability of its n-doped states for prospective “in-water” applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping-induced “collapse” of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n-doped states in water and the high electron conductivity of polymers

V-shaped pyranylidene/triphenylamine-based chromophores with enhanced photophysical, electrochemical and nonlinear optical properties

We report the synthesis and comprehensive study of two chromophores based on 4H-pyranylidene moiety as a part of the π-conjugated spacer. Triphenylamine (TPA) acts as donor and tricarbonitrile-based electron-accepting groups complete these V-shaped D–A–D architectures (A, acceptor; D, donor). Their electrochemical, photophysical and nonlinear optical properties are analyzed in detail by using a joint experimental and theoretical approach. The two chromophores exhibit near-infrared fluorescence, large Stokes shift, enhanced emission in tetrahydrofuran/water mixtures and good photostability. Additionally, the dimerization of triphenylamine groups to tetraphenylbenzidine (TPB) takes place upon electrochemical and chemical oxidation showing their peculiar electrochemical behavior and film formation capabilities. Interestingly, high molecular first hyperpolarizabilities and two-photon absorption cross-sections were found, highlighting their potential applications in electro-optical devices. Overall, our work demonstrates that these near-infrared (NIR) fluorescent chromophores are versatile materials with a myriad of applications ranging from optoelectronics to biological applications.The work at the University of Málaga was funded by the MICINN (PID2019-110305GB-I00, PID2019-104293GB-I00, RTI2018-095410-B-I00, EuroNanoMed 2019 PCI2019-111825-2), the Institute of Health Carlos III (ISCIII) RETIC ARADYAL (RD16/0006/0012) and by the Junta de Andalucıa (P09-FQM-4708, UMA18-FEDERJA-080, UMA18-FEDERJA-007, PIER-0084-2019). The work at the University of Zaragoza was funded by the MICINN (PID2019-104307GB-I00/AEI/10.13039/501100011033) and Gobierno de Aragón (E47_20R). The work at the University of Stuttgart was funded by the German Science Foundation (DFG) through the project “LU 1445/7-1, project number 416982273” on electrooptical hybrid modulators, C. Malacrida is acknowledged for discussions. S. G.-V. thanks the MINECO for a FPU predoctoral fellowship (FPU17/04908) and CB-M for FPU fellowship (FPU16/02516). Computer resources, technical expertise and assistance provided by the SCBI (Supercomputing and Bioinformatics) centre of the University of Málaga are gratefully acknowledged. We thank the Vibrational spectroscopy lab (EVI) of the Research Central Services (SCAI) of the University of Málaga and John Pearson (BIONAND) for help with laser confocal microscopy analysis. We gratefully acknowledge the ICTS “NANBIOSIS” facilities, more specifically the U28 Unit of the Andalusian Centre for Nanomedicine & Biotechnology (BIONAND), for their help with the 2PA characterization and the microscopy studies.Peer reviewe

Hybrid spintronic materials from conducting polymers with molecular quantum bits

Hybrid materials consisting of organic semiconductors and molecular quantum bits promise to provide a novel platform for quantum spintronic applications. However, investigations of such materials, elucidating both the electrical and quantum dynamical properties of the same material have never been reported. Here the preparation of hybrid materials consisting of conducting polymers and molecular quantum bits is reported. Organic field‐effect transistor measurements demonstrate that the favorable electrical properties are preserved in the presence of the qubits. Chemical doping introduces charge carriers into the material, and variable‐temperature charge transport measurements reveal the existence of mobile charge carriers at temperatures as low as 15 K. Importantly, quantum coherence of the qubit is shown to be preserved up to temperatures of at least 30 K, that is, in the presence of mobile charge carriers. These results pave the way for employing such hybrid materials in novel molecular quantum spintronic architectures.European Union's Horizon 2020 Research and Innovation ProgrammeCenter for Integrated Quantum Science and Technology (IQST)Carl Zeiss FoundationProjekt DEA

Visualization and 3D Reconstruction of Flame Cells of Taenia solium (Cestoda)

BACKGROUND: Flame cells are the terminal cells of protonephridial systems, which are part of the excretory systems of invertebrates. Although the knowledge of their biological role is incomplete, there is a consensus that these cells perform excretion/secretion activities. It has been suggested that the flame cells participate in the maintenance of the osmotic environment that the cestodes require to live inside their hosts. In live Platyhelminthes, by light microscopy, the cells appear beating their flames rapidly and, at the ultrastructural, the cells have a large body enclosing a tuft of cilia. Few studies have been performed to define the localization of the cytoskeletal proteins of these cells, and it is unclear how these proteins are involved in cell function. METHODOLOGY/PRINCIPAL FINDINGS: Parasites of two different developmental stages of T. solium were used: cysticerci recovered from naturally infected pigs and intestinal adults obtained from immunosuppressed and experimentally infected golden hamsters. Hamsters were fed viable cysticerci to recover adult parasites after one month of infection. In the present studies focusing on flame cells of cysticerci tissues was performed. Using several methods such as video, confocal and electron microscopy, in addition to computational analysis for reconstruction and modeling, we have provided a 3D visual rendition of the cytoskeletal architecture of Taenia solium flame cells. CONCLUSIONS/SIGNIFICANCE: We consider that visual representations of cells open a new way for understanding the role of these cells in the excretory systems of Platyhelminths. After reconstruction, the observation of high resolution 3D images allowed for virtual observation of the interior composition of cells. A combination of microscopic images, computational reconstructions and 3D modeling of cells appears to be useful for inferring the cellular dynamics of the flame cell cytoskeleton

Multiscale investigation of sodium‐ion battery anodes: analytical techniques and applications

The anode/electrolyte interface behavior, and by extension, the overall cell performance of sodium-ion batteries is determined by a complex interaction of processes that occur at all components of the electrochemical cell across a wide range of size- and timescales. Single-scale studies may provide incomplete insights, as they cannot capture the full picture of this complex and intertwined behavior. Broad, multiscale studies are essential to elucidate these processes. Within this perspectives article, several analytical and theoretical techniques are introduced, and described how they can be combined to provide a more complete and comprehensive understanding of sodium-ion battery (SIB) performance throughout its lifetime, with a special focus on the interfaces of hard carbon anodes. These methods target various length- and time scales, ranging from micro to nano, from cell level to atomistic structures, and account for a broad spectrum of physical and (electro)chemical characteristics. Specifically, how mass spectrometric, microscopic, spectroscopic, electrochemical, thermodynamic, and physical methods can be employed to obtain the various types of information required to understand battery behavior will be explored. Ways are then discussed how these methods can be coupled together in order to elucidate the multiscale phenomena at the anode interface and develop a holistic understanding of their relationship to overall sodium-ion battery function. Here, several analytical methods across multiple time and length scales are discussed, covering a wide range of physical and (electro)chemical properties. To fully grasp the complexity of sodium-ion battery anodes, integrated studies on the same battery system, ranging from the cellular level to the atomic level, are required.imag