Pyrenoimidazole‐Based Deep‐Blue‐Emitting Materials: Optical,Electrochemical, and Electroluminescent Characteristics

A series of pyrenoimidazoles that contained various functional chromophores, such as anthracene, pyrene, triphenylamine, carbazole, and fluorene, were synthesized and characterized by optical, electrochemical, and theoretical studies. The absorption spectra of the dyes are dominated by electronic transitions that arise from the pyrenoimidazole core and the additional chromophore. All of the dyes exhibited blue‐light photoluminescence with moderate‐to‐high quantum efficiencies. They also displayed high thermal stability and their thermal‐decomposition temperatures fell within the range 462–512 °C; the highest decomposition temperature was recorded for a carbazole‐containing dye. The oxidation propensity of the dyes increased on the introduction of electron‐rich chromophores, such as triphenylamine or carbazole. The application of selected dyes that featured additional chromophores such as pyrene, carbazole, and triphenylamine as blue‐emissive dopants into multilayered organic light‐emitting diodes with a 4,4′‐bis(9H‐carbazol‐9‐yl)biphenyl (CBP) host was investigated. Devices that were based on triphenylamine‐ and carbazole‐containing dyes exhibited deep‐blue emission (CIE 0.157, 0.054 and 0.163, 0.041), whereas a device that was based on a pyrene‐containing dye showed a bright‐blue emission (CIE 0.156, 0.135).     

Approximations of solutions to neutral functional differential equations with nonlocal history conditions

This work is concerned with a class of neutral functional differential equations with nonlocal history conditions in a Hilbert space. The approximation of solution to a class of such problems is studied. Moreover, the convergence of Faedo-Galerkin approximation of solution is shown. For illustration, an example is worked out.     

Intersonic crack propagation in homogeneous media under shear-dominated loading: theoretical analysis

The mechanics of cohesive failure under mixed-mode loading is investigated for the case of a steadily propagating subsonic and intersonic dynamic crack subjected to a follower tensile and shear distributed load. The cohesive failure model chosen in this study is rate independent but accounts for the coupling between normal and tangential damage. Special emphasis is placed here on mixed-mode cases with predominantly shear loading. The analysis shows that the size of the mixed-mode cohesive zone is smaller than that obtained in the pure shear case. The relative extent of the shear and tensile cohesive damage zones depends on the crack speed and the mode mixity. In the intersonic regime, the failure process takes place exclusively in shear, even under remote mixed-mode loading conditions.     

Synthesis and characterizations of water-based ferrofluids of substituted ferrites [Fe1−xBxFe2O4, B=Mn,Co (x=0–1)] for biomedical applications

Nanomagnetic particles have great potential in the biomedical applications like MRI contrast enhancement, magnetic separation, targeting delivery and hyperthermia. In this paper, we have explored the possibility of biomedical applications of [Fe_1−xB_xFe₂O₄, B=Mn, Co] ferrite. Superparamagnetic particles of substituted ferrites [Fe_1−xB_xFe₂O₄, B=Mn, Co (x=0–1)] and their fatty acid coated water base ferrofluids have been successfully prepared by co-precipitation technique using NH4OH/TMAH (Tetramethylammonium hydroxide) as base. In vitro cytocompatibility study of different magnetic fluids was done using HeLa (human cervical carcinoma) cell lines. Co²⁺-substituted ferrite systems (e.g. CoFe₂O₄) is more toxic than Mn²⁺-substituted ferrite systems (e.g. MnFe₂O₄, Fe_0.6Mn_0.4Fe₂O₄). The later is as cytocompatible as Fe₃O₄. Thus, Fe_1−xMn_xFe₂O₄ could be useful in biomedical applications like MRI contrast agent and hyperthermia treatment of cancer.     

Optimization of a high-performance liquid chromatography method for the separation and identification of six different classes of phenolics

Flavonoids are chemical moieties widely distributed in certain plants that are important biologically active constituents of a daily human diet, with significant pharmacological potential (anti-hepatotoxic, anti-allergic, anti-inflammatory, anti-osteoporotic, and anti-tumor activities). Thus keeping in view the importance of this class of compounds, a rapid method for the separation and identification of fifteen phenols belonging to six different types of phenolics in a sole analysis has been developed and validated using selectivity, precision, recovery, and robustness as parameters. The method developed, which is rapid, accurate, and robust for the analysis of different classes of phenols, can be used in the quality control and standardization of plant extracts as well as herbal drugs, including compound herbal formulations.     

Synthesis and Characterization of PANI/ZnO Nanocomposites

This paper presents our results on the successful fabrication of HCl‐doped polyaniline (PANI)/ZnO nanocomposites via an electrochemical synthesis route. Different weight percents of ZnO nanoparticles were uniformly dispersed in the PANI matrix. The interaction between the dispersed ZnO nanoparticle and PANI was studied using X‐ray diffraction, ultraviolet–visible absorption spectroscopy, photoluminescence (PL) spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, thermogravimetry, and transmission electron microscopy. It is shown that the doping state of the PANI/ZnO nanocomposite is highly improved as compared to that of PANI. The dispersed PANI/ZnO nanocomposites exhibit enhanced PL behavior and thermal stability.     

Magnetic hyperthermia with biphasic gel of La1−xSrxMnO3 and maghemite

Magnetic hyperthermia experiments were carried out using a biphasic gel of La_1−xSr_xMnO₃(LSMO) and γ-Al_0.07 Fe_1.93O₃ with an AC magnetic field of amplitude 88 mT and a frequency of 108 kHz. Specific absorption rate (SAR) increases with the increased ratio of Al-substituted maghemite. The T_max value for the gels prepared by the mixture of LSMO and Al-substituted maghemite can be adjusted to suit therapeutic temperature. The time required to reach optimum temperature decreased with the increased ratio of later. Such biphasic gel could be very useful for magnetic hyperthermia with in vivo control of temperature.     

Neuroprotective effect of peroxiredoxin 6 against hypoxia-induced retinal ganglion cell damage

Background  

The ability to respond to changes in the extra-intracellular environment is prerequisite for cell survival. Cellular responses to the environment include elevating defense systems, such as the antioxidant defense system. Hypoxia-evoked reactive oxygen species (ROS)-driven oxidative stress is an underlying mechanism of retinal ganglion cell (RGC) death that leads to blinding disorders. The protein peroxiredoxin 6 (PRDX6) plays a pleiotropic role in negatively regulating death signaling in response to stressors, and thereby stabilizes cellular homeostasis.