In-Depth Understanding of the Relation between CuAlO₂ Particle Size and Morphology for Ozone Gas Sensor Detection at a Nanoscale Level

A morphology-dependent nanomaterial for energy and environment applications is one of the key challenges for materials science and technology. In this study, we investigate the effect of the particle size of CuAlO₂ nanostructures prepared through the facile and hydrothermal process to detect ozone gas. Phase analysis and structural information were obtained using X-ray diffraction and micro-Raman studies. The chemical states of CuAlO₂ atomic species were determined by X-ray photoelectron spectroscopy. Electron microscopy images revealed the flower and hexagonal shape constituted of pentagon and oval CuAlO₂ nanoparticles with average size ∼40 and 80 nm. The specific surface area was measured and found to be 59.8 and 70.8 m² g^–1, respectively. The developed CuAlO₂ nanostructures not only possess unique morphology but also influence the ozone gas sensing performance. Among the two structures, CuAlO₂, with hexagonal morphology, exhibited superior ozone detection for 200 ppb at 250 °C, with a response and good recovery time of 25 and 39 s compared to the flower morphology (28 and 69 s). These results show that not only does the morphology play an major role but also the particle size, surface area, gas adsorption/desorption, and grain–grain contact, as proposed in the gas sensing mechanism. Finally, we consider CuAlO₂ material as a good candidate for environment monitoring applications

Synthesis of optically active seven-membered 1,5-anhydrocarbasugars and 1,4,5-tribenzoyloxy-2-ethoxy cycloheptanes via [5+2] cycloaddition

[5+2] Cycloaddition followed by asymmetric dihydroxylation procedure have been utilized to prepare novel cyclitols. Accordingly, rac-2 alpha-hydroxy-6 alpha-ethoxy-1,5-anhydro cyclohept-3-ene, 10 derived from [5+2] cycloaddition of 3-oxidopyrylium ylide and vinyl ether has been recognized as a seven-membered carbasugar equivalent and elaborated to 1,4,5-tribenzoyloxy-2-ethoxy cycloheptanes through a flexible, regio- and stereoselective strategy involving Sharpless asymmetric dihydroxylation conditions to resolve the compounds obtained. The structures and relative configurations of newly synthesized (+)-2 alpha-acetoxy-6 alpha-ethoxy-3 beta,4 beta-dihydroxy-1,5-anhydro cycloheptane ((+)-12)); (-)-1 beta,4 beta,5 beta-tribenzoyloxy-6 alpha-ethoxy cycloheptane ((-)-17) and (+)-1 alpha,4 alpha,5 alpha-tribenzoyloxy-6 beta-ethoxy cycloheptane ((+)-17) are unambiguously established by single crystal X-ray analysis and duly supported by H-1 and C-13 NMR spectroscopy data. (C) 2012 Elsevier Ltd. All rights reserved

Development of a Single-Step Antibody–Drug Conjugate Purification Process with Membrane Chromatography

Membrane chromatography is routinely used to remove host cell proteins, viral particles, and aggregates during antibody downstream processing. The application of membrane chromatography to the field of antibody-drug conjugates (ADCs) has been applied in a limited capacity and in only specialized scenarios. Here, we utilized the characteristics of the membrane adsorbers, Sartobind® S and Phenyl, for aggregate and payload clearance while polishing the ADC in a single chromatographic run. The Sartobind® S membrane was used in the removal of excess payload, while the Sartobind® Phenyl was used to polish the ADC by clearance of unwanted drug-to-antibody ratio (DAR) species and aggregates. The Sartobind® S membrane reproducibly achieved log-fold clearance of free payload with a 10 membrane-volume wash. Application of the Sartobind® Phenyl decreased aggregates and higher DAR species while increasing DAR homogeneity. The Sartobind® S and Phenyl membranes were placed in tandem to simplify the process in a single chromatographic run. With the optimized binding, washing, and elution conditions, the tandem membrane approach was performed in a shorter timescale with minimum solvent consumption and high yield. The application of the tandem membrane chromatography system presents a novel and efficient purification scheme that can be realized during ADC manufacturing