Density functional theory and infrared spectroscopy were used to determine the structure of N,O-dilithio-2-(N-methylamino)ethanol, a mixed intramolecular aggregate. The calculations indicated that the cyclic form of this compound is more stable than the open form, and that conclusion is consistent with the infrared spectra. The solid-state spectra showed lower Li−N and Li−O vibrational frequencies than were calculated for the gas phase, which is consistent with coordination of lithium to electronegative atoms on adjacent molecules in the solid state.
The active packaging materials fabricated using natural polymers is increasing in recent years. Electrohydrodynamic processing has drawn attention in active food packaging due to its potential in fabricating materials with advanced structural and functional properties. These materials have the significant capability in enhancing food's quality, safety, and shelf-life. Through electrospinning and electrospray, fibers and particles are encapsulated with bioactive compounds for active packaging applications. Understanding the principle behind electrohydrodynamics provides fundamentals in modulating the material's physicochemical properties based on the operating parameters. This review provides a deep understanding of electrospray and electrospinning, along with their advantages and recent innovations, from food packaging perspectives. The natural polymers suitable for developing active packaging films and coatings through electrohydrodynamics are intensely focused. The critical properties of the packaging system are discussed with characterization techniques. Furthermore, the limitations and prospects for natural polymers and electrohydrodynamic processing in active packaging are summarized.
The efficient production of allyl alcohol from glycerol is of great importance due to its significance as a valuable intermediate in chemical industries. While catalytic conversion of glycerol to allyl...
Ion implantation and thermal annealing have been used to produce a wide range of nanocrystals and quantum dots in amorphous (SiO{sub 2}) and crystalline (Al{sub 2}O{sub 3}) matrices. Nanocrystals of metals (Au), elemental semiconductors (Si and Ge), and even compound semiconductors (SiGe, CdSe, CdS) have been produced. In amorphous matrices, the nanocrystals are randomly oriented, but in crystalline matrices they are three dimensionally aligned. Evidence for photoluminescence and quantum confinement effects are presented.
Understanding and enhancing thermal transport in polymers is of great importance, and is necessary to enable next-generation flexible electronics, heat exchangers, and energy storage devices. Over the past several decades, significant enhancement of the thermal conductivity of polymeric materials has been achieved, but several key questions related to the effects of molecular structure on thermal transport still remain. By studying a series of electrospun vinyl polymer nanofibers, we investigate the relationship between thermal conductivity and both molecular chain length and side group composition. For polyethylene nanofibers with different molecular weights, the measured thermal conductivity increases monotonically with molecular chain length, as energy transport along molecular chains is more efficient than between chains. The observed trend is also consistent with structural characterization by Raman spectroscopy, which shows enhanced crystallinity as molecular weight increases. Further, by comparing the measured thermal conductivity of vinyl polymer nanofibers with different side groups, we found that phonons travel along polymer chains more effectively when the side groups are either lighter or more symmetric. These experimental results help reveal the underlying correlation between the molecular structure and thermal conductivity of polymer nanofibers, providing valuable insights into the design of polymeric materials with enhanced thermal conductivity.
Egyptian Blue (EB, Cuprorivaite, CaCuSi 4 O 10 ) is a novel candidate for nanomaterial-based sensors in water, as its infrared (IR, 910 nm) emission has high quantum yield in comparison with current commonly-used IR reporters. IR signals for bioimaging and environmental sensing penetrate biological matrices (i.e. tissues) deeper and with less scattering than visible light. This work reports the effects of heating rate on the solid state synthetic yield of EB and formation mechanism is discussed. EB synthesis was investigated with thermogravimetric analysis coupled with mass spectrometry and in-situ high temperature X-ray diffraction. A reproducible maximum in EB yield was observed at a heating rate of 7 °C/min with samples containing CaCO 3 precursor. We report the optimized reaction conditions, yields, and the photoluminescent response of the synthesized EB layered materials. The precursor content (O 2 , CaCO 3 , CuO and SiO 2 ) also had a subtle effect on EB yield.
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