Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

A novel catalyst-free synthetic approach to 1,2,3-triazolobenzodiazepinones has been developed and optimized. The Ugi reaction of 2-azidobenzaldehyde, various amines, isocyanides, and acids followed by microwave-assisted intramolecular azide–alkyne cycloaddition (IAAC) gave a series of target heterocyclic compounds in moderate to excellent yields. Surprisingly, the normally required ruthenium-based catalysts were found to not affect the IAAC, only making isolation of the target compounds harder while the microwave-assisted catalyst-free conditions were effective for both terminal and non-terminal alkyne

Comparison of Ammonia Sensing Characteristics of Individual SnO2 Nanowire and SnO2 Sol-gel Nanocomposite

AbstractSnO2 chemical sensors were fabricated by two different methods. The first one was based on contacting individual nanowires by in situ nanofabrication in a Focused Ion Beam (FIB) microscope. The second one, the traditional sol-gel method, was based on tin dioxide nanopowder thermal agglomeration. Both types of sensors were capable of detecting air-diluted NH3 to the parts per million level. The responses to this gas were studied at different concentrations and operating temperatures, showing up reproducible characteristics. Their performances were discussed in relation to the accepted mechanisms for NH3 sensing in n-type metal oxides. Investigations were made on device stability, demonstrating that these nanowires have some advantages in comparison with sol-gel sensors

Enhanced piezoelectric response of hybrid biodegradable 3D poly(3-hydroxybutyrate) scaffolds coated with hydrothermally deposited ZnO for biomedical applications

Fibrous scaffolds based on biodegradable piezoelectric poly(3-hydroxybutyrate) (PHB) polymers were fabricated via electrospinning. Hydrothermal deposition of zinc oxide (ZnO) on the surfaces of fibrous PHB scaffolds resulted in a homogeneous ZnO layer that grew conformally on the porous polymeric scaffold. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results confirmed the formation of a hexagonal wurtzite crystal structure of ZnO on the PHB fibres. XRD patterns, TEM and EDS analysis revealed a bimodal morphology with rod-like nanostructures that grew preferentially along the c-axis as well as nanoparticles that grew randomly. The piezoelectric charge coefficient d(33) for pristine PHB scaffolds was 2.9 +/- 0.1 pC.N-1, whereas after ZnO deposition, it substantially increased to 13.7 +/- 1.6 pC.N-1. Moreover, the output surface electrical potential of PHB scaffolds after ZnO deposition also substantially increased from 0.58 +/- 0.02 to 0.88 +/- 0.04 V, showing enhanced electromechanical coupling in the piezoelectric nanocomposites. The output surface electric potential for ZnO-coated PHB scaffolds was stable within 1200 loading cycles. In addition, the ZnO rod-like nanostructured surface improved the wettability of PHB fibrous scaffolds, demonstrating synergy between the ceramic and polymeric phases in PHB/ZnO composites. Therefore, the hybrid biodegradable piezoelectric scaffolds reported in the present study are potentially useful for biomedical applications, where both improved piezoelectric response and surface wettability are required