Effects of Hydrogen Bonding and Molecular Chain Flexibility of Substituted n-Alkyldimethylsilanes On Impact Ice Adhesion Shear Strength

The effects of hydrogen bonding and molecular flexibility upon ice adhesion shear strength were investigated using aluminum substrates coated with substituted n-alkyldimethylalkoxysilanes. The location of the chemical group substitution was on the opposing end of the linear n-alkyl chain with respect to silicon. Three hydrogen-bonding characteristics were evaluated: 1) non-hydrogen bonding, 2) donor/acceptor, and 3) acceptor. Varying the length of the n-alkyl chain provided an assessment of molecular chain flexibility. Coated and uncoated aluminum surfaces were characterized by receding water contact angle and surface roughness. Ice adhesion shear strength was determined in the Adverse Environment Rotor Test Stand facility from -16 to -8C that simulated aircraft in-flight icing conditions within the FAR Part 25/29 Appendix C icing envelope. Surface roughness of the coatings was similar allowing for comparison of the test results. An adhesion reduction factor, based on the ice adhesion shear strength data with respect to uncoated aluminum obtained at the same temperature, was calculated to compare the data. The results revealed complex interactions with impacting supercooled water droplets that were interdependent upon ice accretion temperature, surface energy characteristics of water and ice, hydrogen bonding characteristic of the substituent, and length of the n-alkyl chain. To aid in explaining the results, 1) changes in the surface energy component (i.e., non-polar and polar) values that water undergoes during its phase change from liquid to solid that arise from the freezing of impacting supercooled water droplets on the surface depended upon the temperature during accretion were taken into account and 2) the physical properties (i.e., water solubility and melting point) of small compounds analogous to the substituted n-alkyldimethylalkoxysilanes used in this study were compared

Reduction of wood hygroscopicity and associated dimensional response by repeated humidity cycles

The reduction of wood response to variations of ambient humidity, described as kind of ageing, has been studied from both points of view of moisture uptake and dimensional changes. Clearwood specimens from 3 gymnosperms (Pinus sylvestris L., Pinus pinaster Ait., Pinus insignis Dougl.) and 4 angiosperms (Populus spp., Quercus pyrenaica Willd., Entandrophragma cylindricum Sprague, Chlorophora excelsa Benth. & Hook f.) were subjected to five wet-dry cycles and their moisture content and dimensional changes in radial and tangential direction at three increasing levels of relative humidity (57.6, 84.2 and 90.2%) were measured before and after the treatment. For a given increase of relative humidity, a coefficient of hygroscopic ageing was defined as the relative decrease of moisture uptake, and the coefficient of dimensional ageing as the difference of swelling strain before and after ageing. All species exhibited a clear ageing effect, much stronger in the wet range than in the dry range. Calculation of swelling coefficients suggested that in some cases the relation between swelling strain and moisture content is no longer linear in aged wood.Comment: to be published in Annals of Forest Scienc

<Contributed Talk 24>Heteroclinic Cycles in Coupled Systems with Applications to Sensor Devices

[Date] November 28 (Mon) - December 2 (Fri), 2011: [Place] Kyoto University Clock Tower Centennial Hall, Kyoto, JAPA

TRUSS: Tracking Risk with Ubiquitous Smart Sensing

We present TRUSS, or Tracking Risk with Ubiquitous Smart Sensing, a novel system that infers and renders safety context on construction sites by fusing data from wearable devices, distributed sensing infrastructure, and video. Wearables stream real-time levels of dangerous gases, dust, noise, light quality, altitude, and motion to base stations that synchronize the mobile devices, monitor the environment, and capture video. At the same time, low-power video collection and processing nodes track the workers as they move through the view of the cameras, identifying the tracks using information from the sensors. These processes together connect the context-mining wearable sensors to the video; information derived from the sensor data is used to highlight salient elements in the video stream. The augmented stream in turn provides users with better understanding of real-time risks, and supports informed decision-making. We tested our system in an initial deployment on an active construction site.Intel CorporationMassachusetts Institute of Technology. Media LaboratoryEni S.p.A. (Firm

Design and Development of a Laboratory-Scale Ice Adhesion Testing Device

When an aircraft traverses through clouds containing supercooled water droplets, in-flight icing can occur that negatively affects vehicle performance by increasing weight and drag leading to loss of lift. Super-cooled water droplets present in clouds that impact vehicle surfaces can lead to inflight icing any time during the year.1 Most events occur at temperatures ranging from 0 to -20degC. Ice generated on the aircraft can vary between clear/glaze, rime, and mixed (Fig. 1) depending on air temperature (-5 to -20degC), liquid water content (0.3-0.6 g/m3), and droplet size (median volumetric diameter of 15-40 m). Current strategies to remove ice are based on active technologies such as pneumatic boots, heated surfaces, and deicing agents (i.e., ethylene- and propylene-based glycols). The latter have potential environmental concerns. A passive approach to mitigate accreting ice that is actively being investigated are protective coatings. An ice mitigating coating could potentially be used as a stand-alone material, but more likely in combination with an active approach. In the latter scenario, potential reduction in power consumption by the active approach may be realized. To determine the ice adhesion strength of impact ice that is representative of the aircraft environment is not a trivial matter. Test methods utilizing slowly formed ice (i.e., freezer ice) do not accurately simulate this environment. Likewise, some testing methodologies involve sample relocation from the icing environment to the test chamber that can result in thermal shock to the sample, thus affecting the results. The Adverse Environment Rotor Test Stand (AERTS) located at Pennsylvania State University (PSU) has been demonstrated to simulate impact icing conditions within the icing envelope for the determination of ice adhesion shear strength (IASS) without removal/relocation of the sample.2 Due to the confidence in results obtained from AERTS, this instrument is in high demand and requires a significant amount of lead time and capital investment to obtain IASS results. As a solution for quickly and economically screening coatings in a controlled manner under impact icing conditions, a laboratory-scale ice adhesion test and dead blades were then removed from the rotor/blade assembly to obtain the final mass. The IASS of the live blade was determined from the difference in mass (before and after testing) of the live and dead blades, the ice shed area, and the rpm of the shed event. The same live blade sample was tested in triplicate at all three test temperatures. Surface roughness was determined using a Bruker Dektak XT Stylus Profilometer. Measurements were conducted using a 12.5 m tip at a vertical range of 65.5 m with an applied force of 3 mg. Data were collected over a 1.0 mm length at a resolution of 0.056 m/point. Five single line scans at different locations were collected and processed using a two-point leveling subtraction. The resultant Ra (arithmetic roughness) and Rq (root mean square roughness) average values were calculated

Effect of Molecular Flexibility upon Ice Adhesion Shear Strength

Ice formation on aircraft surfaces effects aircraft performance by increasing weight and drag leading to loss of lift. Current active alleviation strategies involve pneumatic boots, heated surfaces, and usage of glycol based de-icing fluids. Mitigation or reduction of in-flight icing by means of a passive approach may enable retention of aircraft capabilities, i.e., no reduction in lift, while reducing the aircraft weight and mechanical complexity. Under a NASA Aeronautics Research Institute Seedling activity, the effect of end group functionality and chain length upon ice adhesion shear strength (IASS) was evaluated with the results indicating that chemical functionality and chain length (i.e. molecular flexibility) affected IASS. Based on experimental and modeling results, diamine monomers incorporating molecular flexibility as either a side chain or in between diamine functionalities were prepared, incorporated into epoxy resins that were subsequently used to fabricate coatings on aluminum substrates, and tested in a simulated icing environment. The IASS was found to be lower when molecular flexibility was incorporated in the polymer chain as opposed to a side chain

Resonant Enhancement of Inelastic Light Scattering in the Fractional Quantum Hall Regime at ν=1/3\nu=1/3

Strong resonant enhancements of inelastic light scattering from the long wavelength inter-Landau level magnetoplasmon and the intra-Landau level spin wave excitations are seen for the fractional quantum Hall state at $\nu = 1/3$. The energies of the sharp peaks (FWHM $\lesssim 0.2meV$) in the profiles of resonant enhancement of inelastic light scattering intensities coincide with the energies of photoluminescence bands assigned to negatively charged exciton recombination. To interpret the observed enhancement profiles, we propose three-step light scattering mechanisms in which the intermediate resonant transitions are to states with charged excitonic excitations.Comment: 5 pages, 5 figure

Predicción de pancreatitis poscolangiopancreatografía retrógrada mediante el uso de niveles séricos de amilasa y lipasa después de 4 horas

Introducción. La predicción temprana de la pancreatitis (PEP) posterior a la colangiopancreatografía retrógrada endoscópica (CPRE) puede permitir el alta segura de los pacientes ambulatorios el mismo día después de la CPRE y un manejo adecuado más temprano. Objetivo. &nbsp;Este estudio tuvo como objetivo evaluar la utilidad de los niveles de amilasa y lipasa sérica 4 horas después de la CPRE para la predicción temprana de PEP e investigar los valores de corte predictivos para los niveles de amilasa y lipasa sérica 4 horas después de la CPRE para el alta segura y el inicio urgente. de reanimación.&nbsp;Metodología. Se revisaron retrospectivamente los datos de 516 pacientes consecutivos con papila nativa que se sometieron a CPRE entre enero de 2020 y agosto de 2022 en el Hospital General Macas.&nbsp;Resultados. Los niveles séricos de amilasa y lipasa se midieron antes y 4 y 24 horas después de la CPRE.&nbsp;PEP ocurrió en 16 (3,1%) pacientes. Valores de&nbsp;p&nbsp;&lt;&nbsp;0,001).&nbsp;El nivel de amilasa &gt; 1,5 × el límite superior de referencia (ULR) resultó útil para la exclusión de PEP con una sensibilidad del 93,8 %, mientras que 4 × ULR resultó útil para guiar la terapia preventiva con la mejor especificidad del 93,2 %.&nbsp;De manera similar, el nivel de lipasa 2 × ULR mostró la mejor sensibilidad, mientras que 8 × ULR tuvo la mejor especificidad.&nbsp;El análisis de regresión logística mostró que 4 horas después de la CPRE, el nivel de amilasa &gt; 4 × ULR, el nivel de lipasa &gt; 8 × ULR, la esfinterotomía precortada y la esfinterotomía pancreática fueron predictores significativos de PEP. Conclusión. &nbsp;En conclusión, los niveles de amilasa y lipasa 4 horas después de la CPRE son predictores tempranos útiles de PEP que pueden garantizar un alta segura o una reanimación rápida después de la CPRE.A previsão precoce de pancreatite (PEP) após colangiopancreatografia retrógrada endoscópica (CPRE) pode permitir a alta segura de pacientes ambulatoriais no mesmo dia após a CPRE e o manejo adequado mais cedo. Mirar. &nbsp;Este estudo teve como objetivo avaliar a utilidade dos níveis séricos de amilase e lipase 4 horas após CPRE para a predição precoce de FEP e investigar os valores de corte preditivos para os níveis séricos de amilase e lipase 4 horas após CPRE para alta segura e início urgente. de ressuscitação. Métodos. Dados de 516 pacientes consecutivos com papila nativa submetidos a CPRE entre janeiro de 2020 e agosto de 2022 foram revisados ​​retrospectivamente. Resultados. Os níveis séricos de amilase e lipase foram medidos antes e 4 e 24 horas após a CPRE. A PEP ocorreu em 16 (3,1%) pacientes. valores de p &lt; 0,001). O nível de amilase &gt; 1,5 × limite superior de referência (ULR) foi útil para exclusão de PEP com sensibilidade de 93,8%, enquanto 4 × ULR foi útil para orientar a terapia preventiva com a melhor especificidade de 93,2%. Da mesma forma, o nível de lipase 2 × ULR apresentou a melhor sensibilidade, enquanto o 8 × ULR apresentou a melhor especificidade. A análise de regressão logística mostrou que 4 horas após a CPRE, nível de amilase &gt; 4 × RUL, nível de lipase &gt; 8 × RUL, esfincterotomia pré-corte e esfincterotomia pancreática foram preditores significativos de PEP. Conclusão. &nbsp;Em conclusão, os níveis de amilase e lipase 4 horas após a CPRE são preditores precoces úteis de PEF que podem garantir alta segura ou ressuscitação rápida após a CPRE

Target-independent high-throughput sequencing methods provide evidence that already known human viral pathogens play a main role in respiratory infections with unexplained etiology

Despite the advanced PCR-based assays available, a fraction of the pediatric respiratory infections remain unexplained every epidemic season, and there is a perception that novel viruses might be present in these specimens. We systematically collected samples from a prospective cohort of pediatric patients with respiratory infections, that returned negative results by validated molecular RT-PCR assays, and studied them with a target-independent, high-throughput sequencing-based approach. We also included a matched cohort of children with no symptoms of respiratory infection, as a contrast study population. More than fifty percent of the specimens from the group of patients with unexplained respiratory infections were resolved. However, the higher rate of detection was not due to the presence of novel viruses, but to the identification of well-known viral respiratory pathogens. Our results show that already known viral pathogens are responsible for the majority of cases that remain unexplained after the epidemic season. High-throughput sequencing approaches that use pathogen-specific probes are easier to standardize because they ensure reproducible library enrichment and sequencing. In consequence, these techniques might be desirable from a regulatory standpoint for diagnostic laboratories seeking to benefit from the many advantages of these sequencing technologies.This work was supported by The Joint Science and Technology Office for Chemical and Biological Defense (JSTO-CBD) of the Defense Threat Reduction Agency (DTRA) under plan #CB10246. This study has been partially supported by Fondo de Investigaciones Sanitarias (FIS) – Spanish Health Research Fund Grant PI12/01291, and Instituto de Salud Carlos III (ISCIII), Grant PI15CIII/00028.S