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The extrusion of dendrites and gas bubbles can lead to the appearance of dead lithium, which seriously reduces the coulomb efficiency, hindering the rapid development of high‐energy batteries. Therefore, it is very important to study the internal mechanism of the interaction between lithium dendrites and gas bubbles during electrochemical processes. In this paper, we have designed and developed a special in situ observation device for investigating the dendrite behavior. We also modified the phase‐field model to study the growth of lithium dendrites on the electrode with bubbles. The cantilever beam theory was applied to study the interaction between lithium dendrites and gas bubbles. The observed effects comprise the coalescence of gas bubbles, changing of lithium‐ion transport path on graphite electrode surface near the gas bubble, and bending of dendrites in front of the bubble. The local variation in the lithiation speed can be attributed to the insulating properties of the gas bubbles. Phase‐field simulation results of the interaction between dendrites and gas bubbles were consistent with the experimental results. A deeper insight into the gas‐bubble behaviors during dendrite growth with the presented simulation and experiment techniques becomes possible, which could be helpful to choose an appropriate structural design for reducing bubbles and lithium dendrites. [ABSTRACT FROM AUTHOR]

Temperature-dependent modulus of glass fiber/epoxy composite laminates was studied at temperatures ranging from room temperature up to 120℃. The storage modulus, loss modulus, loss factor, and glass transition temperature of two layer-up composite laminates were investigated by dynamic mechanic analysis. Static flexural modulus was also measured by control force mode in dynamic mechanic analysis. A new and simple temperature-dependent model both for the dynamic storage modulus and static flexural modulus was developed. This model depends only on one parameter which has specific physical meaning. The model prediction showed excellent agreement with our own experimental results over the full range of transition region. Furthermore, comparing our model’s prediction and other experimental data of many types of composites, which were studied by other researchers, we point to the fact that our model can be applied to many different polymer matrix composites. [ABSTRACT FROM AUTHOR]

Surface Enhanced Raman Scattering (SERS) combined with Thin Layer Chromatography (TLC) has been used for studying characteristic spectrum of molecules in situ in micrograms samples. There are very few report for applying the SERS-TCL method in the study of the effective ingredients of Chinese traditional herbs. Coptis Chinensis France is an often-used clinic Chinese traditional medicine. Its main effective components include berberine and so on, which have antibiotic very wide and also have curative effect on improving the functions of heart vascular cycles. Therefore the concentrations of berberine are very important for the quality control of the medicine. In this work, the ethanol extract of Coptis Chinensis France was first separated by TLC, the SERS was then measure directly after dropping silver gel on the separated spots. The method can be used for the finger print analysis of the berberine. 3 microL of alcohol extract of Coptis Chinensis France with total alkaloids concentration of 1.0 mg.mL was placed on silicon GF254 TLC plate. The sample was separated by developing solvent of n bulanol-Acitic acid-H2O (7:2:1 V/V). The positions of berberine in the sample were confirmed by the standard alkaloid solutions. The Rf values for berberine are 0.29. The silver gel was used as surface enhanced substrate and placed on the separated berberine spots. FT-SERS was measured directly by a Nicolet FT-Raman 910 spectrometer. Berberine belong to isoquinoline alkaloids. His structure can be found in reference. The date of spectrum of berberine can be seen that the band at 1,396 cm-1 due to Ar-OCH3 deformation vibrations was greatly enhanced, indicating that the molecule was absorbed on silver gel strongly through lone-pair electron in Ar-OCH3. The ring stretching mode occurring around 1,548 cm-1 represents isoquinoline ring in the molecule. The band at 727 cm-1 due to CH (ring) deformation vibrations was also enhanced.