Hydroxide anion conducting solid polymer membranes, also termed anion exchange membranes, are becoming important materials for electrochemical technology, and activity in this field, spurred by renewed interest in alkaline fuel cells, is experiencing a resurgence. Solid polymer anion exchange membranes enable alkaline electrochemistry in devices such as fuel cells and electrolyzers and serve as a counterpoint to proton exchange membranes, of which there is a large body of literature. For their seeming importance, the details of transport in alkaline exchange membranes has not been explored thoroughly. In this work, a chloromethylated polymer with a polysulfone backbone was synthesized. 1 H NMR spectroscopy was performed to determine the chloromethyl content and its position on the polymer structure. The chloromethylated polymer was solution cast to form clear, creasable films, and subsequent soaking of these films in aqueous trimethylamine gave benzyltrimethylammonium groups. The resulting anion exchange membranes swell in water and show varying degrees of ionic conductivity depending on their ion exchange capacity. The water mobility in the anion exchange membranes was greater than in previously studied proton exchange membranes; however, the transport properties in these new materials were lower than what might have been expected from the water behavior. This comparison gives some insight as to future anion exchange membrane design objectives.

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A model membrane system composed of egg sphingomyelin (SM), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol was studied with static and magic angle spinning (31)P NMR spectroscopy. This model membrane system is of significant biological relevance since it is known to form lipid rafts. (31)P NMR under magic angle spinning conditions resolves the SM and DOPC headgroup resonances allowing for extraction of the (31)P NMR parameters for the individual lipid components. The isotropic chemical shift, chemical shift anisotropy, and asymmetry parameter can be extracted from the spinning side band manifold of the individual components that form liquid-ordered and liquid-disordered domains. The magnitude of the (31)P chemical shift anisotropy and the line width is used to determine headgroup mobility and monitor the gel-to-gel and gel-to-liquid crystalline phase transitions of SM as a function of temperature in these mixtures. Spin-spin relaxation measurements are in agreement with the line width results, reflecting mobility differences and some heterogeneities. It will be shown that the presence of DOPC and/or cholesterol greatly impacts the headgroup mobility of SM both above and below the liquid crystalline phase transition temperature, whereas DOPC displays only minor variations in these lipid mixtures.

Bioencapsulation of living cells into silica materials derived from the sol–gel process has resulted in novel hybrid living materials with exciting functionalities. Despite the many successes in this field, long-term viability and activity of the encapsulated cells remain a significant obstacle to producing practical and robust devices, e.g., whole-cell-based biosensors. We report the first study on the effects of various media additives and the metabolic phase of encapsulated cells on long-term viability and the rate of inducible gene expression. Saccharomyces cerevisiae (S. cerevisiae) cells, genetically engineered to produce yellow fluorescent protein (YFP) in response to galactose, were encapsulated in poly(glycerol) silicate derived matrices. Surprisingly, we find that addition of media components to the glycerol-silica matrix adversely impacted long-term viability in all cases studied, with a 1.3, 1.4, or 5.4 fold decrease in viability after only 9 days of storage in matrices containing yeast peptone dextrose (YPD), yeast peptone (YP, no glucose), or Synthetic Complete (SC) +2% glucose media, respectively. These findings are attributed to the media components inducing exit of the cells from the more robust quiescent state, and the metabolic production of toxic byproducts. Encapsulated cells from exponential culture exhibited inducible reporter gene expression rates approximately 33% higher than cells from stationary cultures. Addition of media components to the silica matrix increased gene expression rates under certain conditions. These results further elaborate on other silica matrix encapsulated living cell studies, and provide important design parameters for developing effective living cell-based biosensors for case-specific detection applications.

The implementation of direct standardization (DS), piecewise direct standardization (PDS), and double-window piecewise direct standardization (DWPDS) instrumental transfer techniques for high-resolution (1)H NMR spectral data was explored. The ability to transfer a multivariate calibration model developed for a "master or target" NMR instrument configuration to seven different ("secondary") NMR instrument configurations was measured. Partial least-squares (PLS) calibration of glucose, glycine, and citrate metabolite relative concentrations in model mixtures following mapping of the secondary instrumental configurations using DS, PDS, or DWPDS instrumental transfer allowed the performance of the different transfer methods to be assessed. Results from these studies suggest that DS and PDS transfer techniques produce similar improvements in the error of prediction compared to each other and provide a significant improvement over standard spectral preprocessing techniques including reference deconvolution and spectral binning. The DS instrumental transfer method produced the largest percent improvement in the predictions of concentrations for these model mixtures but, in general, required that additional transfer calibration standards be used. Limitations of the different instrumental transfer methods with respect to sample subset selection are also discussed.

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The established view is that vibrotactile stimuli evoke two qualitatively distinctive cutaneous sensations, flutter (frequencies < 60 Hz) and vibratory hum (frequencies > 60 Hz), subserved by two distinct receptor types (Meissner’s and Pacinian corpuscle, respectively), which may engage different neural processing pathways or channels and fulfil quite different biological roles. In psychological and physiological literature, those two systems have been labelled as Pacinian and non-Pacinian channels. However, we present evidence that low-frequency spike trains in Pacinian afferents can readily induce a vibratory percept with the same low frequency attributes as sinusoidal stimuli of the same frequency, thus demonstrating a universal frequency decoding system. We achieved this using brief low-amplitude pulsatile mechanical stimuli to selectively activate Pacinian afferents. This indicates that spiking pattern, regardless of receptor type, determines vibrotactile frequency perception. This mechanism may underlie the constancy of vibrotactile frequency perception across different skin regions innervated by distinct afferent types.

When eyewitnesses are exposed to misinformation about an event from a co-witness,