High performance non-doped green organic light emitting diode via delayed fluorescence

P. G. thanks the Science & Engineering Research Board (SERB), India, for the Start-up Research Grant (SRG) (Grant No: SRG/2020/000161). E.Z-C. thanks the Engineering and Physical Sciences Research Council (EPSRC) EP/P010482/1 for support. P. R. thanks the Indian Institute of Science (IISc) for generous financial support and the Science & Engineering Research Board (SERB), India, for the SERB-Power Grant (SPG) (Grant No: SPG/2020/000107). B.S. thank IISc for the C. V. Raman Fellowship under the Institute of Eminence (IoE).Non-doped, delayed fluorescence organic light-emitting diodes (OLEDs) provide a route to high performance devices and simplified device fabrication. Here, two ambipolar anthracene derivatives containing a hole-transporting di-p-tolylamine and a carbazole and an electron-transporting phosphine oxide moiety are rationally designed and synthesized. The thermal and optoelectronic properties were investigated and the neat films of these compounds show high photoluminescence quantum yields of 84–87%. Non-doped OLEDs with these luminogens exhibit green emission at ∼545 nm and an EQEmax of over 7.2% due to the delayed fluorescence resulting from triplet–triplet annihilation (TTA). The devices show a high luminance of over 104 400 cd m−2. Power efficiency and current efficiency maxima are up to 23.0 lm W−1 and 28.3 cd A−1, respectively. Moreover, the devices show very low efficiency roll-off and retain 90% of the maximum efficiency even at 20 000 cd m−2. When combined with a thermally activated delayed fluorescent (TADF) assistant dopant, the green-emitting OLEDs show a high EQEmax of 17.8%.PostprintPeer reviewe

Structural analysis of haemoglobin binding by HpuA from the Neisseriaceae family

The Neisseriaceae family of bacteria causes a range of diseases including meningitis, septicaemia, gonorrhoea and endocarditis, and extracts haem from haemoglobin as an important iron source within the iron-limited environment of its human host. Herein we report crystal structures of apo- and haemoglobin-bound HpuA, an essential component of this haem import system. The interface involves long loops on the bacterial receptor that present hydrophobic side chains for packing against the surface of haemoglobin. Interestingly, our structural and biochemical analyses of Kingella denitrificans and Neisseria gonorrhoeae HpuA mutants, although validating the interactions observed in the crystal structure, show how Neisseriaceae have the fascinating ability to diversify functional sequences and yet retain the haemoglobin binding function. Our results present the first description of HpuA’s role in direct binding of haemoglobin

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Prospect and potential of Burkholderia sp. against Phytophthora capsici Leonian: a causative agent for foot rot disease of black pepper

Foot rot disease is a very destructive disease in black pepper in Malaysia. It is caused by Phytophthora capsici Leonian, which is a soilborne pathogenic protist (phylum, Oomycota) that infects aerial and subterranean structures of many host plants. This pathogen is a polycyclic, such that multiple cycles of infection and inoculum production occur in a single growing season. It is more prevalent in the tropics because of the favourable environmental conditions. The utilization of plant growth-promoting rhizobacteria (PGPR) as a biological control agent has been successfully implemented in controlling many plant pathogens. Many studies on the exploration of beneficial organisms have been carried out such as Pseudomonas fluorescens, which is one of the best examples used for the control of Fusarium wilt in tomato. Similarly, P. fluorescens is found to be an effective biocontrol agent against the foot rot disease in black pepper. Nowadays there is tremendous novel increase in the species of Burkholderia with either mutualistic or antagonistic interactions in the environment. Burkholderia sp. is an indigenous PGPR capable of producing a large number of commercially important hydrolytic enzymes and bioactive substances that promote plant growth and health; are eco-friendly, biodegradable and specific in their actions; and have a broad spectrum of antimicrobial activity in keeping down the population of phytopathogens, thus playing a great role in promoting sustainable agriculture today. Hence, in this book chapter, the potential applications of Burkholderia sp. to control foot rot disease of black pepper in Malaysia, their control mechanisms, plant growth promotion, commercial potentials and the future prospects as indigenous PGPR were discussed in relation to sustainable agriculture

The role of reduced graphene oxide capping on defect induced ferromagnetism of ZnO nanorods

In this study, the effect of different numbers of layers of reduced graphene oxide (RGO) on the ferromagnetic behavior of zinc oxide-reduced graphene oxide (ZnO-RGO) hybrid architectures has been investigated. Scanning and transmission electron microscopy along with x-ray diffraction of these hybrids confirm that ZnO nanorods are wrapped with different numbers of layers of RGO in a controlled way and their hexagonal phase is unaffected by these layers. Raman and photoelectron spectroscopy of these hybrids reveals that RGO does not alter the nonpolar optical phonon E-2 (high) mode and chemical state of Zn2+ in ZnO. Electron paramagnetic resonance (EPR) spectra show that RGO passivates singly charged oxygen vacancies (V-OS(+)) in ZnO. It correlates the passivation efficiency of V-OS(+) to the number of RGO layers and this has been achieved up to 90% by similar to 31 layers of RGO. Due to passivation of V-OS(+) in ZnO by RGO, the ferromagnetic behavior (saturation magnetization and divergence between zero field cooled and field cooled) in ZnO-RGO hybrids is suppressed as compared to ZnO. Combining the EPR and magnetic behavior, a direct link between the passivation of the singly charged oxygen vacancies present on the surface of ZnO nanorods and the number of RGO layers is established

TRANSFORMATION STUDIES OF M-TYPE TO W-TYPE HEXAFERRITE IN BAFE12-2XCO3XO19

Samples of general formula BaFe12-2xCo3xO19 (x=0.1, 0.3, 0.5) have been synthesized by ceramic as well as citrate gel routes. The X-ray diffraction patterns indicate that M-type phase forms for x=0.1, while W-type phase is favourable for x=0.3 and 0.5. The results tor x=0.3 are particularly interesting. While the X-ray diffraction data show evidence of a monophasic W-type hexaferrite, the magnetic, thermal and microstructural investigations indicate a secondary phase presumably at grain boundaries. Transformation of M- to W-type hexaferrite has been explained in terms of different possibilities such as nucleation of secondary phases, formation of vacancies and different site occupation of ions in the structure

Magnetic properties of nizr substituted barium ferrite

Single-domain fine particles of NiZr substituted barium ferrite has been synthesized by citrate gel route:The magnetization value obtained are comparable with those observed in Co-Ti substitution. This has been attributed to strong preference of Ni(2+) for octahedral coordination, and no particular preference for Zr(4+) ion. Phase formation at lower temperature permits easy control over the microstructure and hence, a large variation in coercivity (180-4500 Oe) has been possible as a function of x and heat treatment temperature. (C) 1999 Elsevier Science B.V. All rights reserved

A variable temperature ferromagnetic resonance study of Ni-Zr-substituted non-stoichiometric barium ferrite samples

Ferromagnetic resonance (FMR) was performed at X-band (9.6 GHz) on spherical samples of polycrystalline Ni-Zr-substituted non-stoichiometric barium ferrite with several different substitution fractions and heat-treatment temperatures in the temperature range 110-295 K. Large shifts in the FMR line positions and linewidths were observed as functions of temperature in these samples; however, their temperature variations were observed to be opposite to each other. This is explained to be due to the large anisotropic nature of the samples. The standard theory of FMR was invoked to provide an explanation of the data obtained. (C) 1998