In this paper we demonstrate photonic band-edge laser emission from emulsion-based polymer dispersed liquid crystals. The lasing medium consists of dye-doped chiral nematic droplets dispersed within a polymer matrix that spontaneously align as the film dries. Such lasers can be easily formed on single substrates with no alignment layers. The system combines the self-organizing periodic structure of chiral nematic liquid crystals with the simplicity of the emulsion procedure so as to produce a material that retains the emission characteristics of band-edge lasers yet can be readily coated. Sequential and stacked layers demonstrate the possibility of achieving simultaneous multi-wavelength laser output from glass, metallic, and flexible substrates.
Abstract. Low concentrations of ice-nucleating particles (INPs) are thought to be important for the properties of mixed-phase clouds, but their detection is challenging. Hence, there is a need for instruments where INP concentrations of less than 0.01 L−1 can be routinely and efficiently determined. The use of larger volumes of suspension in drop assays increases the sensitivity of an experiment to rarer INPs or rarer active sites due to the increase in aerosol or surface area of particulates per droplet. Here we describe and characterise the InfraRed-Nucleation by Immersed Particles Instrument (IR-NIPI), a new immersion freezing assay that makes use of IR emissions to determine the freezing temperature of individual 50 µL droplets each contained in a well of a 96-well plate. Using an IR camera allows the temperature of individual aliquots to be monitored. Freezing temperatures are determined by detecting the sharp rise in well temperature associated with the release of heat caused by freezing. In this paper we first present the calibration of the IR temperature measurement, which makes use of the fact that following ice nucleation aliquots of water warm to the ice–liquid equilibrium temperature (i.e. 0 ∘C when water activity is ∼1), which provides a point of calibration for each individual well in each experiment. We then tested the temperature calibration using ∼100 µm chips of K-feldspar, by immersing these chips in 1 µL droplets on an established cold stage (µL-NIPI) as well as in 50 µL droplets on IR-NIPI; the results were consistent with one another, indicating no bias in the reported freezing temperature. In addition we present measurements of the efficiency of the mineral dust NX-illite and a sample of atmospheric aerosol collected on a filter in the city of Leeds. NX-illite results are consistent with literature data, and the atmospheric INP concentrations were in good agreement with the results from the µL-NIPI instrument. This demonstrates the utility of this approach, which offers a relatively high throughput of sample analysis and access to low INP concentrations.
Abstract. Low concentrations of ice nucleating particles (INPs) are thought to be important for the properties of mixed-phase clouds, but their detection is challenging. While instruments to quantify INPs online can provide relatively high time resolution data, they typically cannot quantify very low INP concentrations. Furthermore, typical online instruments tend to report data at a single defined set of conditions. Hence, there is a need for instruments where INP concentrations of less than 0.01 L−1 can be routinely and efficiently determined. The use of larger volumes of suspension in drop assays increases the sensitivity of an experiment to rarer INPs or rarer active sites due to the increase in aerosol or surface area of particulates per droplet. Here we describe and characterise the InfraRed-Nucleation by Immersed Particles Instrument (IR-NIPI), a new immersion freezing assay that makes use of IR emissions to determine the freezing temperature of individual 50 μL droplets each contained in a well of a 96-well plate. Using an IR camera allows the temperature of individual aliquots to be monitored. Freezing temperatures are determined by detecting the sharp rise in well temperature associated with the release of latent the release of heat caused by freezing. In this paper we first present the calibration of the IR temperature measurement, which makes use of the freezing period after initial nucleation when wells warm and their temperature is determined by the ice-liquid equilibrium temperature, i.e. 0 °C when the water activity is ~ 1. We then tested the temperature calibration using ~ 100 µm chips of K-feldspar, by immersing these chips in 1 µL droplets on an established cold stage (µL-NIPI) as well as in 50 µL droplets on IR-NIPI; the results were consistent with one another indicating no bias in the reported freezing temperature. In addition we present measurements of the efficiency of the mineral dust NX-illite and a sample of atmospheric aerosol collected on a filter in the city of Leeds. NX-illite results are consistent with literature data and the atmospheric INP concentrations were in good agreement with the results from the µL-NIPI instrument. This demonstrates the utility of this approach, which offers a relatively high throughput of sample analysis and access to low INP concentrations.
Key indicators: single-crystal X-ray study; T = 120 K; mean (C-C) = 0.002 Å; R factor = 0.044; wR factor = 0.111; data-to-parameter ratio = 12.5.The title compound, C 14 H 13 NO 3 , adopts a twisted conformation in the crystal, with an interplanar angle between the two benzene rings of 87.30 (5) . Molecules within the structure are linked via O-HÁ Á ÁO interactions, forming a hydrogenbonded chain motif with graph set C(7) along the glide plane in the [001] direction. Related literatureFor related phthalamic acid structures, see: Smith et al. (1983) and Bocelli et al. (1989). For the structure of a diaryl amide containing the 2-methoxyphenyl moeity, see: Parra et al. (2001). A description of hydrogen bonding in terms of graph sets is given by Etter (1990) and Bernstein et al. (1995). For standard bond lengths as calculated using crystal structure data, see Allen et al. (2006). ExperimentalCrystal data
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