Xuan Zhao,Dandan Qi,Kaixuan Yang,Chen Chen,Lei Xu,Yaoyao Ying,Tianjiao Li,Dong Liu
This work focused on effects of n- butanol addition on sooting transition process in iso -octane counterflow diffusion flames using optical and chemical diagnostics. Three iso -octane flames were studied with pure iso -octane, a 20% n- butanol addition mixture and a 40% n- butanol addition mixture as fuels. Optical diagnostics was carried out to determine effects of n -butanol addition on the sooting transition process using a high-resolution digital camera based on image processing and transition point extraction methods. Online gas chromatograph was used to investigate the flame chemistry in the sooting transition process. The results showed that the sooting transition point was delayed with the increase of n -butanol addition, which indicated that the addition of n -butanol could suppress the soot formation. To reveal the mechanism for effects of n -butanol on sooting transition process, kinetic simulations were further performed. The experimental results of flame chemistry were compared with the predictions from two mechanisms for iso -octane and n -butanol mixture. Both mechanisms were found to be capable of well capturing the main variations of most species in flames. After n -butanol addition, the changes of fuel-specific primary decomposition products were more obvious. It was noted that the decreased concentration of carbon which was available for benzene formation was the main reason for the delay of sooting transition point with n -butanol additions. Moreover, the inhibition of PAHs growth from n -butanol addition also could contribute to this kind of delayed effects.
Yumin Zhang,Ruoyu Chen,Fugang Liu,Peng Miao,Li Lin,Jian Ye
The detection of deep-seated lesions is of great significance for biomedical applications. However, due to the strong photon absorption and scattering of biological tissues, it is challenging to realize in vivo deep optical detections, particularly for those using the safe laser irradiance below clinical maximum permissible exposure (MPE). In this work, the combination of ultra-bright surface-enhanced Raman scattering (SERS) nanotags and transmission Raman spectroscopy (TRS) is reported to achieve the non-invasive and photosafe detection of “phantom” lesions deeply hidden in biological tissues, under the guidance of theoretical calculations showing the importance of SERS nanotags’ brightness and the expansion of laser beam size. Using a home-built TRS system with a laser power density of 0.264 W cm −2 (below the MPE criteria), we successfully demonstrated the detection of SERS nanotags through up to 14-cm-thick ex vivo porcine tissues, as well as in vivo imaging of “phantom” lesions labeled by SERS nanotags in a 1.5-cm-thick unshaved mouse under MPE. This work highlights the potential of transmission Raman-guided identification and non-invasive imaging toward clinically photosafe cancer diagnoses.
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