This article reviews the state of the art of ultrafast transient absorption microscopy, discusses current experimental concepts and highlights future challenges. The advantages of transient absorption microscopy over other micro‐spectroscopic techniques are its high optical resolution combined with high temporal resolution as well as its ability to study non‐fluorescent and weakly fluorescent molecular species and to probe excited‐state processes. In conventional transient absorption spectroscopy the spectroscopic information usually presents a spatial average over the focal spot of the typically weakly focused probe beam. Transient absorption microscopy, however, enables investigations of the excited state dynamics in individual microscopic areas of a sample. Hence, the technique does not only yield detailed morphological information based on a label‐free molecular contrast, but also gives insight into the ultrafast morphology‐dependent photoinduced processes in heterogeneous samples. Different variations of transient absorption microscopy have found a number of applications ranging from material sciences to biology, which are discussed in this review together with different setup modifications and approaches towards transient absorption spectroscopy with spatial resolution below the diffraction limit.
Proton transfer from the photoacid 8‐hydroxy‐1,3,6‐pyrenetrisulfonic acid (HPTS) to water is studied in reverse micelles with ionic (AOT=sodium dioctyl sulfosuccinate) and non‐ionic (BRIJ‐30=polyoxyethylene(4)lauryl ether) surfactants. The dynamics are studied by probing the transient electronic absorption and transient vibrational absorption, both with sub‐picosecond resolution. The reverse micelle sizes range from approximately 1.6 to 5.5 nm in diameter. For both surfactants it is found that the rate of proton transfer decreases with decreasing reverse micelle size, regardless of surfactant. In addition, for AOT reverse micelles, a fraction of the photoacid molecules exhibit non‐radiative decay, preventing proton transfer. 相似文献
This paper describes approaches for large-volume sample stacking (LVSS) with an EOF pumpin CE for the determination of methotrexate (MTX) and its metabolites in human plasma. After pretreatment of plasma through a SPE cartridge, a large sample volume was loaded by hydrodynamic injection (3 psi, 70 s) into the capillary filled with phosphate buffer (70 mM, pH 6.0) containing 0.01% polyethylene oxide. Following removal of a large plug of sample matrix from the capillary using polarity switching (-25 kV), the separation of anionic analytes was subsequently performed without changing polarity again, achieving an improvement of sensitivity of around a 100-fold. The method was applied to therapeutic drug monitoring of MTX in one acute lymphoblastic leukemia patient. This study is one of very few applications showing the feasibility of LVSS in analysis of biological samples by CE. 相似文献
An additional ultrafast blue shift in the transient absorption spectra of hydrogen-bonding complexes of a strong photoacid, 8-hydroxypyrene 1,3,6-trisdimethylsulfonamide (HPTA), over the solvation response of the uncomplexed HPTA and also over that of the methoxy derivative of the photoacid (MPTA) in the presence of the hydrogen-bonding base was observed on optical excitation of the photoacid. The additional 55 +/- 10 fs solvation response was found to be about 35 % and 19% of the total C(t) of HPTA in dichloromethane (DCM) when it was hydrogen-bonded to dimethylsulfoxide (DMSO) and dioxane, respectively, and about 29% of the total C(t) of HPTA in dichloroethane (DCE) when it was hydrogen-bonded to DMSO. We have assigned this additional dynamic spectral shift to a transient change in the hydrogen bond (O-H...O) that links HPTA to the complexing base, after the electronic excitation of the photoacid. 相似文献
The packed-bed electroosmotic pump (p-EOP) can manipulate liquid with pressure as high as 50 MPa and micro flowrate ranging from several nL/ min to several μL/min1-3. The p-EOP is matching to micro systems and suitable for developing chip liquid chromatography/electrochromatography for proteomics and high throughput HPLC for drug discovery4-6. There are some efforts to improve the performance p-EOP7-8 recently. In this paper, the nanosilica was chosen as the electroosmotic carrier to i… 相似文献
This paper provides a focus on the R&D of solid sorption coolers and heat pumps made in the Luikov Heat & Mass Transfer Institute (CIS Countries Association Heat Pipes) under Thermacore, Inc. Agreement.Commercial and space applications of sorbent systems offer an attractive alternative to compression systems and liquid sorption systems for cooling, heating and air conditioning.MgA zeolites solid sorption systems are analyzed. Some new results are presented.Solid sorption heat pump technology utilizing heat pipe heat recovery with a condensing/evaporating refrigerant holds considerable promise for bivariant (space and domestic) applications due to the variable temperature and variable load capabilities of such machines. 相似文献
Highly expressible bacteriorhodopsin (HEBR) is a light-triggered protein (optogenetic protein) that has seven transmembrane regions with retinal bound as their chromophore to sense light. HEBR has controllable photochemical properties and regulates activity on proton pumping. In this study, we generated HEBR protein and incubated with lung cancer cell lines (A549 and H1299) to evaluate if there was a growth-inhibitory effect with or without light illumination. The data revealed that the HEBR protein suppressed cell proliferation and induced the G0/G1 cell cycle arrest without light illumination. Moreover, the migration abilities of A549 and H1299 cells were reduced by ~17% and ~31% after incubation with HEBR (40 μg/mL) for 4 h. The Snail-1 gene expression level of the A549 cells was significantly downregulated by ~50% after the treatment of HEBR. In addition, HEBR significantly inhibited the gene expression of Sox-2 and Oct-4 in H1299 cells. These results suggested that the HEBR protein may inhibit cell proliferation and cell cycle progression of lung cancer cells, reduce their migration activity, and suppress some stemness-related genes. These findings also suggested the potential of HEBR protein to regulate the growth and migration of tumor cells, which may offer the possibility for an anticancer drug. 相似文献