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71.
72.
Photoacoustic (PA) responses from very-thin poly(methyl methacrylate) (PMMA) films were investigated at various lamination conditions. The PA signal increased when the dye-doped films were laminated up to five layers, but tended to saturate beyond five layers. When the blank films were superimposed on the dye-doped film, the signal became smaller. The signal was larger when the dye-doped film was arranged outermost in the laminated film assembly of dye-doped and blank films. The results imply the effect of film vibration on the PA response. 相似文献
73.
74.
Menglei Zha Dr. Xiangwei Lin Prof. Jen-Shyang Ni Yaxi Li Yachao Zhang Xun Zhang Prof. Lidai Wang Prof. Kai Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23468-23476
Photoacoustic agents have been of vital importance for improving the imaging contrast and reliability against self-interference from endogenous substances. Herein, we synthesized a series of thiadiazoloquinoxaline (TQ)-based semiconducting polymers (SPs) with a broad absorption covering from NIR-I to NIR-II regions. Among them, the excited s-BDT-TQE, a repeating unit of SPs, shows a large dihedral angle and narrow adiabatic energy as well as low radiative decay, attributing to its strongly electron-deficient ester-substituted TQ-segment. In addition, its more vigorous molecular motions trigger a higher reorganization energy that further yields an efficient photoinduced nonradiative decay, which has been carefully examined and understood by theoretical calculation. Thus, BDT-TQE SP-cored nanoparticles with twisted intramolecular charge transfer (TICT) feature exhibit a high NIR-II photothermal conversion efficiency (61.6 %) and preferable PA tracking of in situ hepatic tumor growth for more than 20 days. This study highlights a unique strategy for constructing efficient NIR-II photoacoustic agents via TICT-enhanced PNRD effect, advancing their applications for in vivo bioimaging. 相似文献
75.
Yue Wang Koki Ogasahara Daisuke Tomihama Radomir Mysliborski Masatoshi Ishida Yongseok Hong Yusuke Notsuka Yoshihisa Yamaoka Tomotaka Murayama Atsuya Muranaka Masanobu Uchiyama Shigeki Mori Yuhsuke Yasutake Susumu Fukatsu Dongho Kim Hiroyuki Furuta 《Angewandte Chemie (International ed. in English)》2020,59(37):16161-16166
The synthesis of organometallic complexes of modified 26π‐conjugated hexaphyrins with absorption and emission capabilities in the third near‐infrared region (NIR‐III) is described. Symmetry alteration of the frontier molecular orbitals (MOs) of bis‐PdII and bis‐PtII complexes of hexaphyrin via N‐confusion modification led to substantial metal dπ–pπ interactions. This MO mixing, in turn, resulted in a significantly narrower HOMO–LUMO energy gap. A remarkable long‐wavelength shift of the lowest S0→S1 absorption beyond 1700 nm was achieved with the bis‐PtII complex, t ‐Pt2‐3 . The emergence of photoacoustic (PA) signals maximized at 1700 nm makes t ‐Pt2‐3 potentially useful as a NIR‐III PA contrast agent. The rigid bis‐PdII complexes, t ‐Pd2‐3 and c ‐Pd2‐3 , are rare examples of NIR emitters beyond 1500 nm. The current study provides new insight into the design of stable, expanded porphyrinic dyes possessing NIR‐III‐emissive and photoacoustic‐response capabilities. 相似文献
76.
The photoacoustic spectra of 1-tyrosine hydrazide, 8-hydroxyquinoline and ammonium metavanadate complexes containing Pr, Nd,
Er and Ho have been recorded in the 400–800 nm region using a single beam photoacoustic spectrometer. The main spectral features
in the photoacoustic spectra are found to be due to triply ionized rare-earth atoms and the assignments reveal a red shift
in their spectral features as compared to their positions in the free ions. These shifts have been used to calculate the nephelauxetic
parameters for these complexes. The photoacoustic branching ratios have also been determined and compared with absorption
branching ratios for some of these complexes. 相似文献
77.
Non‐Invasive and In Situ Characterization of the Degradation of Biomaterial Scaffolds by Volumetric Photoacoustic Microscopy 下载免费PDF全文
Dr. Yu Shrike Zhang Xin Cai Dr. Junjie Yao Wenxin Xing Prof. Lihong V. Wang Prof. Younan Xia 《Angewandte Chemie (International ed. in English)》2014,53(1):184-188
Degradation is among the most important properties of biomaterial scaffolds, which are indispensable for regenerative medicine. The currently used method relies on the measurement of mass loss across different samples and cannot track the degradation of an individual scaffold in situ. Here we report, for the first time, the use of multiscale photoacoustic microscopy to non‐invasively monitor the degradation of an individual scaffold. We could observe alterations to the morphology and structure of a scaffold at high spatial resolution and deep penetration, and more significantly, quantify the degradation of an individual scaffold as a function of time, both in vitro and in vivo. In addition, the remodeling of vasculature inside a scaffold can be visualized simultaneously using a dual‐wavelength scanning mode in a label‐free manner. This optoacoustic method can be used to monitor the degradation of individual scaffolds, offering a new approach to non‐invasively analyze and quantify biomaterial–tissue interactions in conjunction with the assessment of in vivo vascular parameters. 相似文献
78.
膜上痕量亚甲蓝样品的间接光声检测 总被引:4,自引:0,他引:4
介绍了一种新的膜上痕量样品分析方法与实验装置。利用间接光声效应对光吸收物质进行检测,全文对方法原理、实验装置以及影响因素进行了详尽讨论。膜上亚甲蓝定量线性范围1×10^-6 ̄1×10^-4mol/L,检出限为46pg。 相似文献
79.
We use a noncontact laser based method to monitor in real time the viscoelastic and thermal properties of thin (micron) polyamic acid films of PMDA/ODA as thermally induced imidization proceeds. Our measurements indicate that the most rapid thermal and viscoelastic changes coincide with or occur at slightly higher temperatures than the peak imidization rate as determined using a variety of other more conventional analytical techniques. The thermal and viscoelastic properties continue to change at temperatures beyond which imidization is largely completed, but within uncertainties cease to change at temperatures greater than 350°C. © 1996 John Wiley & Sons, Inc. 相似文献
80.
The orientation of macromolecular chains in two melt-spun polymer fibers (segmented polyurethane elastomer and melt-modified polyolefine fibers) was studied by photoacoustic spectroscopy (PAS) with polarized light in the mid-infrared range. The PAS orientation functions calculated from the photoacoustic signal intensities of orientation sensitive bands describe the orientation of the different chain segments with respect to the fiber axis. Thus, the orientation of hard and soft segments in the unstressed polyurethane fiber is different and both are similiar to that of the corresponding injection molded bars. With increased spinning velocity an improved orientation of the polyolefine chains along the fiber axis, but only in the amorphous regions of the polymer, were detected. Only a slight reduction of orientation was measured as a result of the subsequent chemical crosslinking in the polyolefines. 相似文献