Influences of support fibers on shapes of heptane/hexadecane droplets in reduced gravity
摘要:
This paper describes analytical and experimental results related to the effects of support fibers on shapes of heptane/hexadecane mixture droplets (both burning and evaporating) in reduced gravity. The experimental results were obtained from large droplets (a few mm) investigated during the MSL-1 Flight of Spacelab. Theoretical (asymptotic) analyses are developed to predict droplet shapes. These analyses, which predict droplet shapes very well, illustrate important aspects of droplet shapes in a transparent fashion. The asymptotic theory shows that for small droplet-fiber contact angles, two spatial zones exist where droplet shapes behave differently. Away from a fiber a droplet is essentially spherical. As the fiber is approached, however deviations from spherical symmetry are significant. Previously developed analytical theory to predict macroscopic droplet shapes also compares well with experimental results. In addition, the experiments indicate that thin liquid films can form on support fibers. In the present experiments, these films apparently lead to transient formation of small droplets/bubbles on the support fibers at locations near the surface of a droplet.
Palladium-catalyzed double arylations of terminal olefins in acetic acid
作者:Daichao Xu、Chunxin Lu、Wanzhi Chen
DOI:10.1016/j.tet.2011.12.017
日期:2012.2
A palladium-catalyzed Heck diarylation of terminalolefins under ligand-free conditions in acetic acid is described. This procedure allows double arylation of terminalolefins affording trisubstituted olefins in good to excellent yields. The methodology is applicable to the coupling of both electron-deficient and electron-rich aryl iodides leading to symmetrical and unsymmetrical β,β-diarylated alkenes
(PhCl) was observed unexpectedly in the Pd-catalyzed cascade Sonogashira–hydroarylation reaction. This new type of carbon–carbonbond forming cross-coupling reaction was efficiently catalysed by Pd2(dba)3 in the presence of a catalytic amount of PhCl, which provides a facile and direct approach to the synthesis of trisubstituted olefins.
New fluorescent compoundscontaining triphenylethylene and tetraphenylethylene moieties were synthesized, and their piezofluorochromic and aggregation‐inducedemission behaviors were investigated. The results show that all compounds exhibit aggregation‐inducedemission characteristics and only the crystalline compound possesses piezofluorochromic properties. The color, emission spectra, and morphological
A series of new aggregation-induced emission compounds with strong blue light-emitting properties derived from triphenylethylene were facilely synthesized by a Wittig–Horner reaction of bis(4-bromophenyl)methanone with diethyl 4-bromobenzylphosphonate, followed by a Suzuki reaction with arylboronic acids. Their maximum fluorescence emission wavelengths were 452–462 nm. The glass transition temperatures ranged from 70–145 °C, and the decomposition temperatures were 360–508 °C. The unoptimized device fabricated with benzofuranyl substituted compound as emitter turned on at ∼6 V, and the maximum luminance was ∼1500 cd m−2.
通过双(4-溴苯基)甲酮与4-溴苄基膦酸二乙酯的Wittig-Horner反应,然后与芳基硼酸进行Suzuki反应,轻松合成了一系列源自三苯乙烯的具有强蓝光发射特性的新型聚集诱导发光化合物。它们的最大荧光发射波长为 452–462 nm。玻璃化转变温度范围为70-145°C,分解温度为360-508°C。使用苯并呋喃基取代的化合物作为发射极制造的未经优化的器件在〜6 V时开启,最大亮度为〜1500 cd m−2。