Physical and electronic properties in multiwalled carbon nanotube–poly(3‐dodecylthiophene) nanocomposites

The properties of nanocomposites of dodecyl ester functionalized multiwalled carbon nanotube (FMWNT) and four poly(3‐dodecyl thiophene) (P3DDT) samples with different molecular weight and chain regioregularity are reported here. Uniform dispersion of FMWNT in the composites is evident from TEM study. π–π and CH–π interactions are evident from FTIR spectra in the low molecular weight (M_w = 8 × 10⁴) and high regiorandom (head‐tail = 69 mol %) P3DDT (ILM) composites; however, such interactions are not so prominent for other P3DDTs. Wide‐angle X‐ray scattering patterns indicate intact interchain lamellar structure of P3DDT in the composites. DSC study shows decrease of main chain melting peak of P3DDT (ILM) with increasing F‐MWNT content but the decrease is lower with higher molecular weight and higher regioregular samples. Dynamic mechanical analyzer study indicates that there is no significant change in the T_g, T_β, and T_γ transition temperature with FMWNT concentration indicating almost ideal mixing of the components. The percent increase of G′ increases with increasing FMWNT loading and also with temperature showing an 84% increase in storage modulus at –20 °C for ILM12 samples. The UV–vis spectrum indicates a decrease in band gap with FMWNT concentration for ILM composites, however, it is negligible with other P3DDTs. Photoluminescence quenching and multiple emission peaks occur in the composites. dc‐Conductivity of the composites increases by two orders and current‐voltage (I–V) curves show memory effect only in ILM‐MWNT composites. The I–V curves of other P3DDT nanocomposites exhibit rectification property. Quantitative explanation of electronic properties has been afforded from the band energy and work function values. So, the electronic properties of the nanocomposite can be tuned by changing the molecular weight, regioregularity, and concentration of FMWNT. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1412–1425, 2009     

A new synthesis of 2-aryl/alkylbenzofurans by visible light stimulated intermolecular Sonogashira coupling and cyclization reaction in water

A visible light induced rapid one pot intermolecular Sonogashira coupling and 5-endo-dig cyclization in water of ortho-halophenols and terminal alkynes catalyzed by [Pd] have been developed to furnish 2-aryl/alkyl benzofurans in good yields sans Ru or Ir complexes or any other additives.     

A multi-loss super regression learner (MSRL) with application to survival prediction using proteomics

Even though a number of regression techniques have been proposed over the years to handle a large number of regressors, due to the complex nature of data emerging from recent high-throughput experiments, it is unlikely that any single technique will be successful in modeling all data types. Thus, multiple regression algorithms from the collection of modern regression techniques that are capable of handling high dimensional regressors should be entertained for analyzing such data. A novel approach of building a super regression learner is proposed which can be fit with a training data set in order to make future predictions of a continuous outcome. The resulting super regression model is multi-objective in nature and mimics the performances of the best component regression models irrespective of the data type. This is accomplished by combining elements of bootstrap based risk calculation, rank aggregation, and stacking. The utility of this approach is demonstrated through its use on mass spectrometry data.     

Zinc Oxide Modified Au Electrode as Sensor for an Efficient Detection of Hydrazine

ZnO nanoparticles (ZnO NPs) prepared by microwave heating technique are used to modify a gold electrode (ZnO/Au) for the hydrazine detection study. The synthesized product is well characterized by various techniques. Detailed electrochemical investigation of the oxidation of hydrazine on the ZnO/Au electrode in 0.02 M phosphate buffer solution (PBS) of pH 7.4 was carried out. A very low detection limit of 66 nM (S/N=4) and a wide linearity in current for a concentration range from 66.0×10^?3 to 415 µM was achieved by amperometry. The electrode was found to be stable for over a month when preserved in PBS.     

Discovery of Inhibitors of Shiga Toxin Type 2 by On‐Plate Generation and Screening of a Focused Compound Library

A new microtiter‐plate‐based method for the rapid generation and evaluation of focused compound libraries was developed and applied to screening ligand analogues for the E. coli Shiga‐like toxin Stx2a. The method is general, it mitigates the masking of intrinsic affinity gains by multivalency and enables the discovery of potential hits when starting from ligands that exhibit extremely low affinity with proteins that depend on multivalency for their function.     

Regiocontrolled Gold‐Catalyzed [2+2+2] Cycloadditions of Ynamides with Two Discrete Nitriles to Construct 4‐Aminopyrimidine Cores

Reported herein is the novel gold‐catalyzed intermolecular [2+2+2] cycloaddition of ynamides with two discrete nitriles to form monomeric 4‐aminopyrimidines, which are pharmaceutically important structural motifs. The utility of this new cycloaddition is demonstrated by the excellent regioselectivity obtained using a variety of ynamides and nitriles.     

Mechanical-Bending-Induced Fluorescence Enhancement in Plastically Flexible Crystals of a GFP Chromophore Analogue

Single crystals of optoelectronic materials that respond to external stimuli, such as mechanical, light, or heat, are immensely attractive for next generation smart materials. Here we report single crystals of a green fluorescent protein (GFP) chromophore analogue with irreversible mechanical bending and associated unusual enhancement of the fluorescence, which is attributed to the strained molecular packing in the perturbed region. Soft crystalline materials with such fluorescence intensity modulations occurring in response to mechanical stimuli under ambient pressure conditions will have potential implications for the design of technologically relevant tunable fluorescent materials.     

Resonance energy transfer from a fluorescent dye to a metal nanoparticle

A quantum mechanical theory of the rate of excitation energy transfer from a fluorescent dye molecule to the surface plasmonic modes of a spherical metal nanoparticle is presented. The theory predicts the distance dependence of the transfer rate to vary as 1/d(sigma), with sigma=3-4 at intermediate distances, in partial agreement with the recent experimental results. F?rster's 1/d(6) dependence is recovered at large separations. The predicted rate exhibits nontrivial nanoparticle size dependence, ultimately going over to an asymptotic, a(3) size dependence. Unlike in conventional fluorescence resonance energy transfer, the orientational factor is found to vary between 1 and 4.