Essential Amino Acid–Enabled Lead Bromide Perovskite Nanocrystals with High Stability

This work reports the first synthesis of MAPbBr₃ perovskite nanocrystals (PNCs) using amino acids as the ligand with excellent optical properties. A variety of amino acids are used to optimize the luminescence properties. A mechanochemical approach has taken lead over conventional colloidal chemistry during synthesis. All morphological and optical studies are performed to characterize the synthesized perovskite nanoparticles. Later, stability studies are investigated through thermogravimetric analysis, temperature‐dependent photoluminescence, time‐dependent X‐ray diffraction, as well as X‐ray photoelectron spectroscopy. In an application, interestingly, these perovskites show high luminescence upon scratching on flexible conducting plates and on plain paper surface. These results suggest that the amino acid–ligated perovskite nanocrystals can be potential materials for optoelectronic application including light‐emitting diodes and imaging.     

Probing surface plasmons by bare V-shaped tips: modeling by geometrical optics and rigorous diffraction theory

Optical Review - We consider probing inhomogeneous waves in the near fields of metallic nanostructures with the aid of a dielectric V-shaped wedge connected to a waveguide. A geometrical model...     

Cigarette smoke extract induced protein phosphorylation changes in human microvascular endothelial cells in vitro

Phosphorylation is the most widely studied posttranslational modification (PTM) and is an important regulatory mechanism used during cellular responses to external stimuli. The kinases and phosphatases that regulate protein phosphorylation are known to be affected in many human diseases. Cigarette smoking causes cardiovascular disease (CVD). Endothelial cells play a pivotal role in CVD initiation and development; however, there have been limited investigations of the specific signaling cascades and protein phosphorylations activated by cigarette smoke in endothelial cells. The purpose of this research was to better understand the differential protein phosphorylation in endothelial cells stimulated with extracts of cigarette smoke total particulate matter (CS-TPM) in vitro. Human microvascular endothelial cells were exposed in vitro to CS-TPM at concentrations that were shown to cause endothelial cell dysfunction. The phosphorylated proteins were isolated using phosphoprotein-specific chromatography, followed by enzymatic digestion and nano-flow capillary liquid chromatography (ncap-LC) coupled to high resolution mass spectrometry. This study putatively identified 94 proteins in human microvascular endothelial cells that were differentially bound to a phosphoprotein-specific chromatography column following exposure to CS-TPM suggesting differential phosphorylation. Pathway analysis has also been conducted and confirmations of several observations have been made using immunoaffinity-based techniques (e.g., Western blotting). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Automation of AMOEBA polarizable force field parameterization for small molecules

A protocol to generate parameters for the AMOEBA polarizable force field for small organic molecules has been established, and polarizable atomic typing utility, Poltype, which fully automates this process, has been implemented. For validation, we have compared with quantum mechanical calculations of molecular dipole moments, optimized geometry, electrostatic potential, and conformational energy for a variety of neutral and charged organic molecules, as well as dimer interaction energies of a set of amino acid side chain model compounds. Furthermore, parameters obtained in gas phase are substantiated in liquid-phase simulations. The hydration free energy (HFE) of neutral and charged molecules have been calculated and compared with experimental values. The RMS error for the HFE of neutral molecules is less than 1 kcal/mol. Meanwhile, the relative error in the predicted HFE of salts (cations and anions) is less than 3% with a correlation coefficient of 0.95. Overall, the performance of Poltype is satisfactory and provides a convenient utility for applications such as drug discovery. Further improvement can be achieved by the systematic study of various organic compounds, particularly ionic molecules, and refinement and expansion of the parameter database.     

Rapid discovery of potent siRNA-containing lipid nanoparticles enabled by controlled microfluidic formulation

The discovery of potent new materials for in vivo delivery of nucleic acids depends upon successful formulation of the active molecules into a dosage form suitable for the physiological environment. Because of the inefficiencies of current formulation methods, materials are usually first evaluated for in vitro delivery efficacy as simple ionic complexes with the nucleic acids (lipoplexes). The predictive value of such assays, however, has never been systematically studied. Here, for the first time, by developing a microfluidic method that allowed the rapid preparation of high-quality siRNA-containing lipid nanoparticles (LNPs) for a large number of materials, we have shown that gene silencing assays employing lipoplexes result in a high rate of false negatives (~90%) that can largely be avoided through formulation. Seven novel materials with in vivo gene silencing potencies of >90% at a dose of 1.0 mg/kg in mice were discovered. This method will facilitate the discovery of next-generation reagents for LNP-mediated nucleic acid delivery.     

All‐Inorganic CsPb1−xGexI2Br Perovskite with Enhanced Phase Stability and Photovoltaic Performance

Compared with organic‐inorganic perovskites, all‐inorganic cesium‐based perovskites without volatile organic compounds have gained extensive interests because of the high thermal stability. However, they have a problem on phase transition from cubic phase (active for photo‐electric conversion) to orthorhombic phase (inactive for photo‐electric conversion) at room temperature, which has hindered further progress. Herein, novel inorganic CsPb_1?xGe_xI₂Br perovskites were prepared in humid ambient atmosphere without a glovebox. The phase stability of the all‐inorganic perovskite was effectively enhanced after germanium addition. In addition, the highest power conversion efficiency of 10.8 % with high open‐circuit voltage (V_OC) of 1.27 V in a planar solar cell based on CsPb_0.8Ge_0.2I₂Br perovskite was achieved. Furthermore, the highest V_OC up to 1.34 V was obtained by CsPb_0.7Ge_0.3I₂Br perovskite, which is a remarkable record in the field of all‐inorganic perovskite solar cells. More importantly, all the photovoltaic parameters of CsPb_0.8Ge_0.2I₂Br perovskite solar cells showed nearly no decay after 7 h measurement in 50–60 % relative humidity without encapsulation.     

Ni selective sensors based on meso-tetrakis-{4-[tris-(4-allyl dimethylsilyl-phenyl)-silyl]-phenyl}porphyrin and (sal)2trien in poly(vinyl chloride) matrix

PVC-based membranes of meso-tetrakis-{4-[tris-(4-allyl dimethylsilyl-phenyl)-silyl]-phenyl}porphyrin (I) and (sal)₂trien (II) as electroactive material with dioctylphthalate (DOP), tri-n-butylphosphate (TBP), chloronapthalene (CN), dibutylphthalate (DBP) and dibutyl(butyl) phosphonate (DBBP) as plasticising solvent mediators have been found to act as Ni²⁺ selective sensor. The best performance was obtained with the sensor having a membrane of composition of I: sodium tetraphenyl borate: PVC in the ratio 5:5:150. The sensor exhibits Nernstian response in the activity range 2.5 × 10⁻⁶ to 1.0 × 10⁻¹ M, performs satisfactorily over wide pH range (2–5.5) with a fast response time (8 s). The sensor was found to work satisfactorily in partially non-aqueous media up to 20% (v/v) content of methanol or ethanol and acetone and could be used over a period of 4 months. Potentiometric selectivity coefficients determined by matched potential method (MPM) indicate excellent selectivity for Ni²⁺ ions. The sensors could be used successfully in the estimation of nickel in different brand of chocolates and also as an indicator electrode in potentiometric titration.     

Adsorption and diffusion of molecular nitrogen in single wall carbon nanotubes

Using molecular simulation, the adsorption and self-diffusion of diatomic nitrogen molecules inside a single wall carbon nanotube have been studied over a range of nanotube diameters (8.61-15.66 A) and loadings at temperatures of 100 and 298 K. Nitrogen adsorption energy is found to increase as the nanotube diameter is reduced toward the molecular diameter of nitrogen. A discrete organization of the nitrogen into adsorbed layers is observed at high loadings that follows a regular progression determined primarily by geometric considerations. The formation of an adsorbate core at the center of the nanotube is found to increase the self-diffusion of nitrogen. A "wormlike" phase is found for the adsorbed nitrogen in the (15, 0) carbon nanotube at high loadings and at 100 K.     

Lewis acid promoted aza Diels-Alder reactions of acyclic unactivated 5-dienyl pyrimidinones with N-arylimines: synthesis of novel quinoline derivatives

The chemo- as well as regioselective aza Diels-Alder reactions of 5-dienyl pyrimidinones with N-arylimines in the presence of a Lewis acid catalyst resulting in novel quinoline derivatives are reported.     

CH activation with an O-donor iridium-methoxo complex

A thermally and air stable O-donor, iridium-methoxo complex is reported that undergoes stoichiometric, intermolecular C-H activation of benzene with co-generation of methanol and the iridium-phenyl complex.