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Melt electrospinning is a facile fabrication technique that can be utilized in the creation of microfibers without the use of solvent and with good control over feature placement. The available thermal energy of the melt electrospinning technique is often only utilized in the formation of the polymer melt but can also be used to thermodynamically drive chemical reactions. In this study, hybrid perovskite microcrystallites are synthesized in the polymer melt and electrospun to form composite microfibers. Unique hybrid perovskite microstructures were studied, elucidating mechanisms of formation at work in the polymer melt.
We have generated models of complete nova energy distributions, including the effects of the nova dust shell emission and absorption. In order to account for the dust, we require optical constants throughout the UV and EUV. Draine & Lee (1984) is the only source of such data for silicates. However, their ‘astronomical silicate’ has a strong resonance in the UV which causes circumnova dust to be heated far above its sublimation temperature in our models of Nova Her 1991. We have therefore recalculated the silicate optical constants, using the Kramers-Kronig relations, including a λ−1.0 far-IR dependence and improved 9.7μm feature, and decreasing the UV and EUV efficiencies of the grains. With these new silicate constants we can reproduce the observed behaviour of the dust shell in Nova Her 1991. Since our optical constants are consistent with the behaviour of Nova Her 1991, an EUV source, they should also be appropriate for the treatment of PN.
We report 10 and 20μm spectroscopic observations of four C–rich post–AGB objects which exhibit the unidentified emission feature at 21μm. The observations were carried out in October 1990 and May 1991 using CGS3 on UKIRT. The spectral resolutions were 70 for the wavelength range of 7.4–13.3μm and 80 for the region between 15.4–24.1μm. Three of the sources reported here are from the list of Kwok, Volk & Hrivnak (1989), i.e., IRAS 04296+3429; IRAS 07134+1005 and IRAS 22272+5435. Figure 1 shows the full spectrum of IRAS 04296+3429 and IRAS 22272+5435. The 10μm spectra of these objects exhibit UIR bands whose peaks all fall longwards of the usual peak wavelengths associated with such features. This may be related to the fact that they are the lowest excitation objects so far found to exhibit UIR emission bands. We also found narrow emission features superimposed on the long wavelength wing of the 21μm emission bands of IRAS 04296+3429 and IRAS 22272+5435. The fourth object we observed, SAO 163075, was found to also exhibit a (weak) 21μm emission feature. However, there is no PAH features in the 10μm region, apart from the plateau at 12μm.
We present mid-IR and far-IR images of a variety of AGB stars and red supergiants. The mid-IR images were all taken with the Berkeley/Livermore mid-IR array camera, which employs a 10 × 64 pixel Hughes photoconductor. All the images reported here were taken using a 10% bandpass CVF, at various wavelengths in the 10μm atmospheric window. These were supplemented by IRAS images, some constructed from survey scans, others made as Additional Observations during the pointed phase of the IRAS mission. We have so far observed 11 such sources with our mid-IR camera, and report here that only two of them (R Aql and V Hya) appear to be unresolved.
The IRAS catalogues have been searched for cool (G,K,M) giant and supergiant stars to investigate the occurrence of circumstellar (C/S)silicate dust, revealed by its emission features at 9.7 and 18μm. Low Resolution Spectrograph (LRS) spectra covering the 7-23μm range were used, plus the 60 and 100μm photometric points. M Supergiants were found in White Wing (1978), other stars by correlating the Bright Star Catalogue with the LRS catalogue: this discriminated against very cool stars reddened by dust; however i t can be seen in Table I that there is a clear trend for cooler and more luminous stars to have a dust shell. M Supergiants almost all have dust shells, whilst only the cooler M bright-giants and giants do. Of the G and K stars, only a very few of the Supergiants have dust shells. The sili cate features fell into two categories:
The results presented here are from an ongoing mid-infrared imaging study of PPNe and PNe, using MIRAC2 the UA/SAO mid-IR camera. Our 8-21 μm observations have a spatial resolution of about 0.7″ to 1.5″, and a pixel scale of 0.25″/pixel (at UKIRT) or 0.34″/pixel (at IRTF). The high S/N and good spatial sampling in our images of IRAS 22272+5435 and IRAS 07134+1005 allow us to construct temperature and optical depth maps. Using our 11.7μm and 20.6μm images we also construct maps which isolate the 11.3μm (UIR) and 21μm emission features (Justannont et al. 1995). As a second part of this project, we are modelling the dust emission from PPNe and young PNe, using a axisymmetrical radiative transfer code.
Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, literacy, and dementia risk factors including apolipoprotein E ε4 status, baseline cognitive performance, and cardiovascular risk. We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. The mean retest effect for general cognitive performance was 0.60 standard deviations (95% confidence interval [0.46, 0.74]), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance (many of whom met criteria for dementia based on a study algorithm), consistent with regression to the mean. Retest did not differ by other characteristics. Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research. (JINS, 2015, 21, 506–518)
The geographic and chronological distribution of eyed bone needles in North American Paleoindian sites led Osborn (2014) to propose that these distinctive artifacts date primarily to the Terminal Pleistocene Younger Dryas Cold Event and were essential to making close-fitting clothes needed to survive frigid winter conditions. Our study of a museum collection from Tule Lake Rock Shelter (CA-SIS-218A) in the high Klamath Basin area supports Osborn’s argument. We present nine high-precision accelerator mass spectrometry (AMS) radiocarbon assays from a 2.5 m deep cultural sequence, demonstrating that Paleoindians occupied the site primarily during the Younger Dryas. Although only about .5 m3 of the Paleoindian deposits at CA-SIS-218A were excavated, fragments of four small bone needles were recovered, three of which contain whole or partial eyes. Two fragments of large mammal cortical bone from the same levels contain remnants of “groove and snap” fractures that may be related to the production of needle blanks. The bone needles from Tule Lake Rock Shelter extend the geographic range of these distinctive Paleoindian artifacts into the high desert region of Northern California.
Teflon amorphous fluoropolymer (TAF) multi-walled carbon nanotube (MWCNT) suspensions have the potential for creating conductive coatings on insulating films for numerous applications. However, there are few studies on polymer MWCNT suspension properties and even fewer that use Teflon. To define mechanical and electrical property relationships, bilayer films of TAF-MWCNT were created with differing concentrations of MWCNTs. Nanoindentation revealed that addition of 8 wt% MWCNTs to TAF increased the elastic modulus by about 25% and hardness by about 15%. Conducting indentation showed 8 wt% MWCNT films exhibit uniform stable conductance once indentation depth exceeds several hundred nanometers. Films with lower concentrations of CNTs were insulating. The two techniques provide a unique description of structure property relationships in this suspension film system.
The use of an antireflection oxide film applicable to laser annealing process has been investigated. The optical properties of the antireflection oxide film are changed by ion implantation although the antireflection characteristics are similar to calculations based on nominal optical constants. Implantation annealing can be achieved at powers lower than predicted by calculations. Using the antireflection(AR) technique, n+-p junction diodes were fabricated. Reverse bias junction leakage is around 10-9 A/cm2 , comparable to those annealed thermally. Short channel MOS devices were also fabricated and indicated much better resistance to the short channel effect than those thermally annealed.
This research focuses on identifying the fracture mechanism in thin film silicon membranes and PZT on silicon composite structures under static and dynamic loading conditions. Square silicon membranes with a 3mm side-length and thickness between 1.5 and 3.0μm, with and without 1.5μm of PZT, were pressurized to failure while laser interferometry was used to determine the maximum strain at failure. The strain at fracture of silicon membranes, initiating from the sharp corner radius inside the micromachined cavity, was improved from 0.37% to 0.8% by an isotropic etch of the sharp corner. Fracture of PZT on silicon membranes, tested at the mechanical resonant frequency suggested that fracture initiates in the blanket PZT layers under reversed bending. Etching the PZT from high strain regions along the membrane surface improved the strain at failure of the composite device by 40%.
Members of the Ruddlesden-Popper system, La2Ni(1-x)CoxO4+δ (0.00 ≤ × ≤ 1.00), were synthesized and studied for their potential use as cathodes for solid-oxide fuel cells. An unusual structural trend has been noted across the series, which appears to correlate with the oxygen-hyperstoichiometry observed. Details of the structural variance by x-ray and neutron diffraction, as well as selected physical properties for this system will be presented.
Co-cultivation of Legionella pneumophila serogroup I and Acanthamoeba palestinensis in Neff's medium at 35 °C resulted in the intracellular multiplication of the bacteria as demonstrated by electron microscopy and immunofluorescence. In the closed experimental system used, the number of legionellae rose from 107 colony forming units (c. f. u.)/ml initially to a maximum of 1010 c. f. u. /ml on day 5. Legionellae were seen in expelled phagosomes, in some amoebae filling the cytoplasm and in others in which the process of encystment appeared to have commenced.
For some while there has been a growing awareness from both internal and external stakeholders that the governance and risk management in United Kingdom (U.K.) insurance companies needed to be enhanced. The proposed European Union Solvency II Directive makes this very explicit and the current economic turmoil has put a much stronger emphasis on the whole process: it is being seen as the right thing to do, rather than simply a regulatory requirement. In this paper, we set out the background to and recent history of governance for U.K. insurance companies, and consider how enterprise risk management can bring together the various control frameworks needed to support that governance. Whilst no two companies are the same, and hence the solutions to these issues will vary, there are several common themes linked to successful implementation. Similarly, various barriers to success are identified, together with solutions to resolve them.
Previous studies have characterized the development of the biological control insects, Galerucella calmariensis and Galerucella pusilla on purple loosestrife and on nontarget Lythraceae species, including two species native to Minnesota, winged loosestrife, and swamp loosestrife. The impact of Galerucella spp. on these plants, when grown in outdoor mesocosms that more closely mimics ecological host range, has not been reported. The first objective of this study was to compare the growth and seed capsule production of purple loosestrife, winged loosestrife, and swamp loosestrife, with and without exposure to Galerucella spp. With purple loosestrife, larval feeding on apical and lateral shoot buds resulted in fewer seed capsules, and reduced aboveground biomass and plant height compared to control plants. No measured plant growth or reproductive parameters were reduced as a result of beetle feeding on swamp loosestrife. Presence of Galerucella spp. on winged loosestrife resulted in a reduction of seed capsules in one of 2 yr of study. A second objective of our study was to compare the phenology of the three Lythraceae species in relation to that of Galerucella spp. In the northern United States, flowering and seed development in swamp loosestrife occurred a month later than in purple or winged loosestrife. The delayed flowering of swamp loosestrife resulted in avoidance of shoot meristem feeding damage caused by the first generation of beetles. Laboratory studies might have overestimated the host range of Galerucella spp. on swamp loosestrife with the finding of asynchronous flowering times of purple and swamp loosestrife. Our mesocosm studies confirm that previous laboratory host range testing did accurately predict the ecological host range of winged loosestrife.
To examine the contribution of genetic factors to food choice, we determined dietary patterns from food frequency questionnaires in 3262 UK female twins aged 18 to 79 years. Five distinct dietary patterns were identified (fruit and vegetable, high alcohol, traditional English, dieting, low meat) that accounted for 22% of the total variance. These patterns are similar to those found in other singleton Western populations, and were related to body mass index, smoking status, physical activity and deprivation scores. Older subjects had higher scores on the fruit and vegetable and traditional English patterns, while lower social deprivation was associated with higher scores for fruit and vegetable, and lower scores for traditional English patterns. All 5 patterns were heritable, with estimates ranging from 41% to 48%. Among individual dietary components, a strongly heritable component was identified for garlic (46%), coffee (41%), fruit and vegetable sources (49%), and red meat (39%). Our results indicate that genetic factors have an important influence in determining food choice and dietary habits in Western populations. The relatively high heritability of specific dietary components implicates taste perception as a possible target for future genetic studies.