MIT Open Access Articles https://hdl.handle.net/1721.1/49433 2020-11-28T13:04:35Z Deuteriodifluoromethylation and gem‐Difluoroalkenylation of Aldehydes Using ClCF2H in Continuous Flow https://hdl.handle.net/1721.1/128668 Deuteriodifluoromethylation and gem‐Difluoroalkenylation of Aldehydes Using ClCF2H in Continuous Flow Fu, Wai Chung; Jamison, Timothy F The deuteriodifluoromethyl group (CF?D) represents a challenging functional group due to difficult deuterium incorporation and unavailability of precursor reagents. Herein, we report the use of chlorodifluoromethane (ClCF?H) gas in the continuous flow deuteriodifluoromethylation and gem-difluoroalkenylation of aldehydes. Mechanistic studies revealed that the difluorinated oxaphosphetane (OPA) intermediate can proceed via alkaline hydrolysis in the presence of D?O to provide α-deuteriodifluoromethylated benzyl alcohols or undergo a retro [2+2] cycloaddition under thermal conditions to provide the gem-difluoroalkenylated product. 2020-06-01T00:00:00Z Large-area electronic skins in space: vision and preflight characterization for first aerospace piezoelectric e-textile https://hdl.handle.net/1721.1/128667 Large-area electronic skins in space: vision and preflight characterization for first aerospace piezoelectric e-textile Cherston, Juliana Mae; Veysset, David Georges; Sun, Yuchen; Yano, Hajime; Nelson, Keith Adam; Murari, Shobha; Paradiso, Joseph A Aerospace-grade textiles have decades of flight heritage for protection against harsh elements of the space environment. However, these substrates have remained electrically passive despite occupying useful large-area real-estate on the exterior walls of persistent spacecraft. By leveraging electronic textiles in an aerospace context, hybrid fabrics can be developed that simultaneously protect spacecraft while also detecting debris or micrometeoroid hypervelocity impactors. Specifically, this paper describes prototype development and preflight testing of piezoelectric Beta cloth ahead of a scheduled late 2020 material resiliency test on the International Space Station. Two accessible manufacturing methods for piezoelectric fiber are introduced based on modifications to piezoelectric cable that reduce diameter, increase mechanical flexibility of the fiber, and improve compatibility with textile weft insertion techniques. A Beta cloth simulant with piezoelectric fiber is introduced and custom ultra low power readout electronics are specified, which allow for a first-order power consumption estimate for scaling of this material across large-area spacecraft walls. Finally, high-velocity impact sensor data measured using the Laser Induced Particle Impact Test (LIPIT) facility is presented, building towards an accurate prediction of impactor velocity. 2020-04-01T00:00:00Z Palm Fruit Bioactives modulate human astrocyte activity in vitro altering the cytokine secretome reducing levels of TNFα, RANTES and IP-10 https://hdl.handle.net/1721.1/128666 Palm Fruit Bioactives modulate human astrocyte activity in vitro altering the cytokine secretome reducing levels of TNFα, RANTES and IP-10 Weinberg, Robert P; Koledova, Vera V; Schneider, Kirsten K; Sambandan, T G; Grayson, Adlai R; Zeidman, Gal; Artamonova, Anastasia; Sambanthamurthi, Ravigadevi; Fairus, Syed; Sinskey, Anthony J; Rha, Chokyun Neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease, are becoming more prevalent and an increasing burden on society. Neurodegenerative diseases often arise in the milieu of neuro-inflammation of the brain. Reactive astrocytes are key regulators in the development of neuro-inflammation. This study describes the effects of Palm Fruit Bioactives (PFB) on the behavior of human astrocytes which have been activated by IL-1β. When activated, the astrocytes proliferate, release numerous cytokines/chemokines including TNFα, RANTES (CCL5), IP-10 (CXCL10), generate reactive oxygen species (ROS), and express specific cell surface biomarkers such as the Intercellular Adhesion Molecule (ICAM), Vascular Cellular Adhesion Molecule (VCAM) and the Neuronal Cellular Adhesion Molecule (NCAM). Interleukin 1-beta (IL-1β) causes activation of human astrocytes with marked upregulation of pro-inflammatory genes. We show significant inhibition of these pro-inflammatory processes when IL-1β-activated astrocytes are exposed to PFB. PFB causes a dose-dependent and time-dependent reduction in specific cytokines: TNFα, RANTES, and IP-10. We also show that PFB significantly reduces ROS production by IL-1β-activated astrocytes. Furthermore, PFB also reduces the expression of ICAM and VCAM, both in activated and na?ve human astrocytes in vitro. Since reactive astrocytes play an essential role in the neuroinflammatory state preceding neurodegenerative diseases, this study suggests that PFB may have a potential role in their prevention and/or treatment. 2018-11-01T00:00:00Z Effect of annealing on magnetic properties in ferrimagnetic GdCo alloy films with bulk perpendicular magnetic anisotropy https://hdl.handle.net/1721.1/128665 Effect of annealing on magnetic properties in ferrimagnetic GdCo alloy films with bulk perpendicular magnetic anisotropy Ueda, Kohei; Tan, Aik Jun; Beach, Geoffrey Stephen Magnetic properties in ferrimagnetic GdCo alloy films with bulk perpendicular magnetic anisotropy (PMA) are investigated as a function of annealing temperature (T anneal ) and annealing time for several capping layers. Magnetic properties in films capped by TaO x vary markedly with T anneal ; the saturation magnetization and coercivity vary progressively with increasing T anneal up to 300°C, and above that temperature, PMA is lost abruptly. By comparing the annealing temperature dependence for Co-dominated and Gd-dominated compositions close to the magnetization compensation point, the data are readily explained by preferential oxidation of Gd during annealing. When films are capped by a Ta/Pt bilayer, the film properties are stable up T anneal = 300 °C, indicating that oxidation at high temperatures is effectively blocked, but the abrupt loss of PMA for T anneal > 300 °C is still observed. X-ray diffraction measurement reveals that the amorphous structure of the films remains the same after high-temperature annealing that is sufficient to remove PMA, indicating that crystallization from the amorphous phase is not responsible for the lack of PMA. Instead, our results suggest that high annealing temperatures may cause segregation of Co and Gd atoms in the films, which reduces anisotropic pair-pair correlations responsible for the observed bulk PMA in the as-grown state. ?2018 Author(s). 2018-12-01T00:00:00Z 狠狠躁天天躁中文字幕_日韩欧美亚洲综合久久_漂亮人妻被中出中文字幕