Diradical Organic One‐Dimensional Polymers Synthesized on a Metallic Surface

We report on the synthesis and characterization of atomically precise one‐dimensional diradical peripentacene polymers on a Au(111) surface. By means of high‐resolution scanning probe microscopy complemented by theoretical simulations, we provide evidence of their magnetic properties, which arise from the presence of two unpaired spins at their termini. Additionally, we probe a transition of their magnetic properties related to the length of the polymer. Peripentacene dimers exhibit an antiferromagnetic (S=0) singlet ground state. They are characterized by singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (J_eff) of 2.5 meV, whereas trimers and longer peripentacene polymers reveal a paramagnetic nature and feature Kondo fingerprints at each terminus due to the unpaired spin. Our work provides access to the precise fabrication of polymers featuring diradical character which are potentially useful in carbon‐based optoelectronics and spintronics.     

Analysis of BiCMOS buffer for input voltages with finite rise time

A BiCMOS digital logic gate is analyzed for input voltages with a finite rise or fall time. A new gate delay model to account for the input slope is developed. A set of accurate yet simple closed-form delay expressions are derived for the first time in terms of the input signal slew rate as well as circuit and device parameters. SPICE simulations are used to verify the accuracy of the analytical delay model. The BiCMOS circuit is characterized in terms of the input slew rate, the fan-in, fan-out, and the circuit delay constants. The model can be incorporated in timing simulators and timing analyzers for BiCMOS ULSI circuit design     

Avoiding bandwidth collapse in long chains of coupled optical microresonators

Coupled photonic oscillators and resonators are sensitive to unavoidable nanoscale disorder, and localization in periodic structures induced by disorder leads eventually to a complete collapse of the bandwidth, which is generally considered problematic for device applications. Here, we investigate the dependence of bandwidth collapse on the interresonator coupling coefficient, a parameter controllable by lithography or device operation.     

Enhancement of the photocatalytic activity of modified ZnO nanoparticles with manganese additive

ZnO nanoparticles were synthesized under mild hydrothermal conditions (T = 150 °C, P = autogenous, experimental duration = 18 h). Manganese was added as an additive to ZnO nanoparticles in different molar percentages. In situ surface-modification was successfully carried out for these manganese-added ZnO nanoparticles using n-butylamine as a surface modifier. The modified manganese-added ZnO nanoparticulates are hydrophilic in nature and are well dispersed in various solvents. The modified nanoparticles were characterized using powder XRD, FTIR, SEM, Zeta potential, and UV?CVis spectrophotometry. The characterization results indicated tailoring of the morphology and size of the nanoparticles, and changing the surface chemistry of the nanoparticles synthesized. The SEM results show that the surface modified manganese-added ZnO nanoparticles have a very thin layer of organic coverage around the inorganic nanoparticles, thus, giving rise to hybrid nanoparticles. The photodegradation of Brilliant Blue dye under sunlight showed the higher efficiency of the modified manganese-doped ZnO nanoparticles compared to the reagent-grade ZnO.     

Oxidative decolorization of indigo caramine dye with chloramine-T catalyzed by cobalt(II)

Decolorization of indigo caramine dye by oxidation process using chloramine-T as oxidant and Co(II) as catalyst in acidic buffer media, pH 5.8 has been kinetically studied at 300 K. Decolorization of indigo caramine dye was followed spectrophotometrically. Decolorization and oxidation led to a decrease in Chemical Oxygen Demand of the dye. The Co(II)-catalyzed reaction shows first-order dependence of the rate on chloramine-T and indigo caramine concentrations. It also shows fractional order dependence on [Co(II)] and [H⁺]. Addition of halide ions or reduction product of chloramine-T toluenesulfonamide, and variation of ionic strength and dielectric constant of the medium do not have any significant effect on the reaction rate. Activation parameters are evaluated from the Arrhenius plot, and a mechanism is proposed for the reaction.     

Functional one,two, and three-dimensional ZnO structures by solvothermal processing

Crystalline zinc oxide (ZnO) has been fabricated by solvothermal techniques under quite different temperature and pressure environment stretching from sub- to supercritical conditions. Among them, one-step processing of inorganic–inorganic hybrid ZnO structures based on ZnO substrate with attached ZnO nanocrystals has been challenged. Combination of doping ions was made to yield ZnO structures with luminescent properties of high potential for application in fast-decay devices. The room temperature decay of antimony, lithium (Sb, Li) codoped homoepitaxial films is reported.     

Novel Quinolone Derivatives: Synthesis and Antioxidant Activity

Russian Journal of General Chemistry - Novel quinolone derivatives have been designed and readily synthesized according to a simple protocol including O-alkylation and Claisen rearrangement...     

Effect of gamma irradiation on synthesis and characterization of bio-nanocomposite SF/Ag nanoparticles

This study describes the synthesis of silver nanoparticles (AgNPs) using aqueous silk fibroin (SF) solution obtained from Bombyx mori silk under gamma radiation environment. The obtained AgNPs were characterized using UV–visible (UV–Vis) spectroscopy, X-ray diffraction (XRD) measurements, dynamic light scattering experiment (DLS) and transmission electron microscope (TEM) images. The UV–Vis absorption spectra of the samples confirmed the formation of AgNPs by showing surface plasmon resonance (SPR) band in the range of (= 428–435?nm. The XRD study revealed metal silver with the face-centered cubic (FCC) crystal structure. DLS measurements showed the dose-dependent average size of the AgNPs. TEM images showed formed AgNPs are nearly spherical in shape with smooth edges. From this study, it was found that the increasing radiation dose increases the rate of reduction and decreases the particle size. The size of the AgNPs can be tuned by controlling the radiation dose.     

Analyzing high-density ECG signals using ICA

The analysis of ECG signals is of fundamental importance for cardiac diagnosis. Conventional ECG recordings, however, use a limited number of channels (12) and each records a mixture of activities generated in different parts of the heart. Therefore, direct observation of the ECG signals collected on the body surface is likely an inefficient way to study and diagnose cardiac abnormalities. This study describes new experimental and analytical methods to capture more meaningful ECG component signals, each representing more directly a physical cardiac source. This study first describes a simply applied method for collecting high-density ECG signals. The recorded signals are then separated by independent component analysis (ICA) to obtain spatially fixed and temporally independent component activations. Results from five subjects show that P-, QRS-, and T-waves can be clearly separated from the recordings, suggesting ICA might be an effective and useful tool for high-density ECG analysis, interpretation, and diagnosis.