Piezoelectricity describes interconversion between electrical charge and mechanical strain. As expected for lattice ions displaced in an electric field, the proportionality constant is positive for ...all piezoelectric materials. The exceptions are poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (P(VDF-TrFE)), which exhibit a negative longitudinal piezoelectric coefficient. Reported explanations exclusively consider contraction with applied electric field of either the crystalline or the amorphous part of these semi-crystalline polymers. To distinguish between these conflicting interpretations, we have performed in situ dynamic X-ray diffraction measurements on P(VDF-TrFE) capacitors. We find that the piezoelectric effect is dominated by the change in lattice constant but, surprisingly, it cannot be accounted for by the polarization-biased electrostrictive contribution of the crystalline part alone. Our quantitative analysis shows that an additional contribution is operative, which we argue is due to an electromechanical coupling between the intermixed crystalline lamellae and amorphous regions. Our findings tie the counterintuitive negative piezoelectric response of PVDF and its copolymers to the dynamics of their composite microstructure.
The complement system is an arm of innate immunity that aids in the removal of pathogens and dying cells. Due to its harmful, pro‐inflammatory potential, complement is controlled by several soluble ...and membrane‐bound inhibitors. This family of complement regulators has been recently extended by the discovery of several new members, and it is becoming apparent that these proteins harbour additional functions. In this review, the current state of knowledge of the physiological functions of four complement regulators will be described: cartilage oligomeric matrix protein (COMP), CUB and sushi multiple domains 1 (CSMD1), sushi domain‐containing protein 4 (SUSD4) and CD59. Complement activation is involved in both the development of and defence against cancer. COMP expression is pro‐oncogenic, whereas CSMD1 and SUSD4 act as tumour suppressors. These effects may be related in part to the complex influence of complement on cancer but also depend on unrelated functions such as the protection of cells from endoplasmic reticulum stress conveyed by intracellular COMP. CD59 is the main inhibitor of the membrane attack complex, and its deficiency leads to complement attack on erythrocytes and severe haemolytic anaemia, which is now amenable to treatment with an inhibitor of C5 cleavage. Unexpectedly, the intracellular pool of CD59 is crucial for insulin secretion from pancreatic β‐cells. This finding is one of several relating to the intracellular functions of complement proteins, which until recently were only considered to be present in the extracellular space. Understanding the alternative functions of complement inhibitors may unravel unexpected links between complement and other physiological systems, but is also important for better design of therapeutic complement inhibition.
Hybrid organic-inorganic perovskites are promising materials for the application in solar cells and light-emitting diodes. However, the basic current-voltage behavior for electrons and holes is still ...poorly understood in these semiconductors due to their mixed electronic-ionic character. Here, we present the analysis of space-charge-limited electron and hole currents in the archetypical perovskite methyl ammonium lead iodide (MAPbI
). We demonstrate that the frequency dependence of the permittivity plays a crucial role in the analysis of space-charge-limited currents and their dependence on voltage scan rate and temperature. Using a mixed electronic-ionic device model based on experimentally determined parameters, the current-voltage characteristics of single-carrier devices are accurately reproduced. Our results reveal that in our solution processed MAPbI
thin films transport of electrons dominates over holes. Furthermore, we show that the direction of the hysteresis in the current-voltage characteristics provides a fingerprint for the sign of the dominant moving ionic species.
The complement system plays a major role in the autoimmune disease, systemic lupus erythematosus (SLE). However, the role of complement in SLE is complex since it may both prevent and exacerbate the ...disease. In this review, we explore the latest findings in complement-focused research in SLE. C1q deficiency is the strongest genetic risk factor for SLE, although such deficiency is very rare. Various recently discovered genetic associations include mutations in the complement receptors 2 and 3 as well as complement inhibitors, the latter related to earlier onset of nephritis. Further, autoantibodies are a distinct feature of SLE that are produced as the result of an adaptive immune response and how complement can affect that response is also being reviewed. SLE generates numerous disease manifestations involving contributions from complement such as glomerulonephritis and the increased risk of thrombosis. Furthermore, since most of the complement system is present in plasma, complement is very accessible and may be suitable as biomarker for diagnosis or monitoring of disease activity. This review highlights the many roles of complement for SLE pathogenesis and how research has progressed during recent years.
Two‐dimensional (2D) titanium carbide (Ti3C2) is emerging as an important member of the MXene family. However, fluoride‐based synthetic procedures remain an impediment to the practical applications ...of this promising class of materials. Here we demonstrate an efficient fluoride‐free etching method based on the anodic corrosion of titanium aluminium carbide (Ti3AlC2) in a binary aqueous electrolyte. The dissolution of aluminium followed by in situ intercalation of ammonium hydroxide results in the extraction of carbide flakes (Ti3C2Tx, T=O, OH) with sizes up to 18.6 μm and high yield (over 90 %) of mono‐ and bilayers. All‐solid‐state supercapacitor based on exfoliated sheets exhibits high areal and volumetric capacitances of 220 mF cm−2 and 439 F cm−3, respectively, at a scan rate of 10 mV s−1, superior to those of LiF/HCl‐etched MXenes. Our strategy paves a safe way to the scalable synthesis and application of MXene materials.
A facile fluoride‐free method has been developed to prepare Ti3C2Tx (T=O, OH) sheets by anodic etching of bulk Ti3AlC2 crystals in aqueous electrolyte. The properties of the delaminated sheets are comparable to those made from classic HF etching procedures.
Exciton diffusion in organic semiconductors Mikhnenko, Oleksandr V; Blom, Paul W. M; Nguyen, Thuc-Quyen
Energy & environmental science,
01/2015, Letnik:
8, Številka:
7
Journal Article
Recenzirano
The purpose of this review is to provide a basic physical description of the exciton diffusion in organic semiconductors. Furthermore, experimental methods that are used to measure the key parameters ...of this process as well as strategies to manipulate the exciton diffusion length are summarized. Special attention is devoted to the temperature dependence of exciton diffusion and its relationship to Förster energy transfer rates. An extensive table of more than a hundred measurements of the exciton diffusion length in various organic semiconductors is presented. Finally, an outlook of remaining challenges for future research is provided.
Experiments and basic Physics of exciton diffusion in organic semiconductors are reviewed.
Ions are ubiquitous biological regulators playing a key role for vital processes in animals and plants. The combined detection of ion concentration and real-time monitoring of small variations with ...respect to the resting conditions is a multiscale functionality providing important information on health states. This multiscale functionality is still an open challenge for current ion sensing approaches. Here we show multiscale real-time and high-sensitivity ion detection with complementary organic electrochemical transistors amplifiers. The ion-sensing amplifier integrates in the same device both selective ion-to-electron transduction and local signal amplification demonstrating a sensitivity larger than 2300 mV V
dec
, which overcomes the fundamental limit. It provides both ion detection over a range of five orders of magnitude and real-time monitoring of variations two orders of magnitude lower than the detected concentration, viz. multiscale ion detection. The approach is generally applicable to several transistor technologies and opens opportunities for multifunctional enhanced bioelectronics.
Highlights • C4BP is a soluble complement inhibitor pivotal for body homeostasis. • Mutations in C4BP are associated with aHUS and pregnancy loss. • C4BP binding to dying cells and amyloid allows for ...their silent removal. • Microbes binding C4BP are protected from complement attack and can cause infections.
Organic semiconductors encounter limitations in their practical applicability in future electronics due to their low environmental stability and poor charge carrier mobilities. Blending with ...isolation of thermoplastic polymers and elastomers circumvents these restrictions and even induces new material properties, opening the door to novel flexible and stretchable electronics that hold great potential for improving people's life. This review discusses next generation applications of solution processable organic semiconductor/insulator blends in organic field‐effect transistors (OFETs). The fundamental basis is a comprehensive understanding of the phase separation mechanism that determines the morphology formation and electronic properties of the thin blend film. Continuous charge carrier pathways in blend OFETs are established by controlled phase separation through the chemical structure of components and the processing conditions. Recent advances in organic semiconductor/insulator blends with enhanced device properties including charge carrier mobility, life‐time, sensing ability, and especially mechanical behavior are reviewed with emphasis on implication in flexible and stretchable electronics. The concept of tuning existing properties and creating new ones of electronically active materials by blending with well‐selected insulators has great potential also for other types of electronic devices and classes of semiconductors.
Blending organic semiconductors with isolating thermoplastic polymers and elastomers improves their environmental stability, device performance, and mechanical properties, opening the door to future flexible and stretchable electronics. This review discusses recent advances in the development of next generation applications of solution processable organic semiconductor/insulator blends in elastic field‐effect transistors and sensors.
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