Hybrid bilayer membranes in air and water: infrared spectroscopy and neutron reflectivity studies

In this report we describe the fabrication and characterization of a phospholipid/alkanethiol hybrid bilayer membrane in air. The bilayer is formed by the interaction of phospholipid with the hydrophobic surface of a self-assembled alkanethiol monolayer on gold. We have characterized the resulting hybrid bilayer membrane in air using atomic force microscopy, spectroscopic ellipsometry, and reflection-absorption infrared spectroscopy. These analyses indicate that the phospholipid added is one monolayer thick, is continuous, and exhibits molecular order which is similar to that observed for phospholipid/phospholipid model membranes. The hybrid bilayer prepared in air has also been re-introduced to water and characterized using neutron reflectivity and impedance spectroscopy. Impedance data indicate that when moved from air to water, hybrid bilayers exhibit a dielectric constant and thickness that is essentially equivalent to hybrid bilayers prepared in situ by adding phospholipid vesicles to alkanethiol monolayers in water. Neutron scattering from these samples was collected out to a wave vector transfer of 0.25 A(-1), and provided a sensitivity to changes in total layer thickness on the order of 1-2 A. The data confirm that the acyl chain region of the phospholipid layer is consistent with that observed for phospholipid-phospholipid bilayers, but suggest greater hydration of the phospholipid headgroups of HBMs than has been reported in studies of lipid multilayers.     

Refinements in the assessment of dementia-related behaviors: Factor structure of the memory and behavior problem checklist.

This study explored the factor structure of the Memory and Behavior Problem Checklist (MBPC) of S. H. Zarit et al (1980), a 29-item inventory that samples negative behavior changes associated with dementia (e.g., incontinence and destroying property). Family caregivers for 185 progressive-dementia patients provided information on their affected relatives. A principal-components factor analysis with an oblique (nonorthogonal) rotation produced an 8-factor solution that accounted for 62.9% of the variance. A second-order factor analysis of the first 5 factors produced a 3-factor solution that accounted for 74.7% of the variance. The 3 factors were (a) self-care and self-maintenance functions, (b) memory problems and psychiatric symptoms associated with dementia, and (c) communication problems and agitation. Correlations between MBPC frequency scores and measures of adaptive ability and level of dementia were high and positive. Potential clinical and research applications of the scale in other related populations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diffusion of Selenium in Liquid-Phase Epitaxy–Grown Hg<Subscript>0.78</Subscript>Cd<Subscript>0.22</Subscript>Te

We present preliminary results on Se diffusion in liquid-phase epitaxy (LPE)–grown HgCdTe epilayers. The LPE Hg_0.78Cd_0.22Te samples were implanted with Se of 2.0 × 10¹⁴/cm² at 100 keV and annealed at 350–450°C in mercury saturated vapor. Secondary ion mass spectrometry (SIMS) profiles were obtained for each sample. From a Gaussian fit, we find that the Se diffusion coefficient D _Se is about 1–2 orders of magnitude smaller than that of arsenic. The as-implanted Se distribution is taken into account in case of small diffusion length in Gaussian fitting. The D _Se was found to satisfy the Arrhenius relationship .     

Properties of InAs/(Ga,In)Sb strained layer superlattices grown on the {111} orientations

Following the proposal of the extreme type-II InAs/(Ga,In)Sb strained layer superlattice system by Mailhiot and Smith in 1987 for long wavelength infrared detection, a number of groups have experimentally investigated (100) oriented InAs/(Ga,In)Sb strained layer superlattices and demonstrated that these structures can possess energy gaps in the 8–12 μm range with absorption coefficients comparable to HgCdTe. However, a number of advantages are predicted if these structures are grown on the {111} orientations. In this paper, we present details of our investigation of the growth of InAs/GaSb heterostructures and InAs/(Ga,In)Sb strained layer superlattices on the (111)A and (111)B orientations by molecular beam epitaxy, compared to growth on the (100) orientation. Heterojunction growth and incorporation rates of Sb (As) into InAs (GaSb) on (111)A, (111)B, and (100) orientations have been assessed and implications for growth and optical properties of InAs/(Ga,In)SB strained layer superlattices are discussed. GaSb/InAs and InAs/GaSb interfaces on the (111)B orientation are investigated by x-ray photoelectron spectroscopy, and the structural quality of InAs/(Ga,In)Sb strained layer superlattices are investigated by x-ray diffraction.     

Hot‐melt adhesives based on co‐polyamide and multiwalled carbon nanotubes

Composites of two hot melt adhesives based on co‐polyamides, one high viscosity (coPA_A), the other low viscosity (coPA_B), and multiwalled carbon nanotubes (MWCNTs) were prepared using twin‐screw extrusion via dilution of masterbatches. Examination of these composites across the length scales confirmed that the MWCNTs were uniformly dispersed and distributed in the polymer matrices, although some micron size agglomerations were also observed. A rheological percolation was determined from oscillatory rheology measurements at a mass fraction of MWCNTs below 0.01 for coPA_B and, between 0.01 and 0.02 for coPA_A. Significant increases in complex viscosity and storage modulus confirmed the “pseudo‐solid” like behavior of the composite materials. Electrical percolation, determined from dielectric spectroscopy was, found to be at 0.03 and 0.01 MWCNT mass fraction for coPA_A and coPA_B based composites, respectively. Addition of MWCNTs resulted in heterogeneous nucleation and altered the crystallization kinetics of both copolymers. Indirect evidence from contact angle measurements and surface energy calculations confirmed that MWCNT addition enhanced the adhesive properties of coPA_B to a level similar to coPA_A. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45999.     

Neutron and X-ray reflectivity analysis of ceramic-metal materials

Neutron and X-ray reflectivity measurements of a thin film of cermet (ceramic-metal) made by co-sputtering Pt and Al₂O₃ on the surface of a flat piece of float glass are presented. From the analysis of the specular and off-specular measurements, the morphology of the Pt clusters which are embedded in the Al₂O₃ matrix is determined by adjusting a model to the observed data. It is found that the structure of such films presents a certain degree of order in the direction normal to the surface of the films but no correlation (or with a very short correlation length not measurable by this technique) in the plane of the film.     

Evaluating an accessibility intervention based on persona cards with diverse needs to teach accessibility to undergraduate students

Universal Access in the Information Society - This paper presents the development and evaluation of an in-class intervention based on persona cards, an accessibility kit created to introduce users...     

Interaction of Regulatory Aspects for Carbon Capture and Utilization Applications

Carbon capture and utilization (CCU) technologies can lead to a net reduction of CO₂ emissions but also to a transfer from emissions between different regulatory areas. This paper presents a tool to evaluate the impact of CCU technology within the European regulatory framework with respect to the accounting of carbon transferred between the CO₂ source and its subsequent application. Additional emissions caused by energy requirements of the capture or any conversion steps are not considered. The tool is applied to a variety of possible combinations and their respective impact evaluated.