Beat-frequency-resolved two-dimensional electronic spectroscopy: disentangling vibrational coherences in artificial fluorescent proteins with sub-10-fs visible laser pulses

We perform a beat-frequency-resolved analysis for two-dimensional electronic spectroscopy using a high-speed and stable 2D electronic spectrometer and few-cycle visible laser pulses to disentangle the vibrational coherences in an artificial fluorescent protein. We develop a highly stable ultrashort light source that generates 5.3-fs visible pulses with a pulse energy of 4.7 uJ at a repetition rate of 10 kHz using multi-plate pulse compression and laser filamentation in a gas cell. The above-5.3-fs laser pulses together with a high-speed multichannel detector enable us to measure a series of 2D electronic spectra, which are resolved in terms of beat frequency related to vibrational coherence. We successfully extract the discrete vibrational peaks behind the inhomogeneous broadening in the absorption spectra and the vibrational quantum beats of the excited electronic state behind the strong stationary signal in the typical 2D electronic spectra

Thrombin Activates Ca2+-permeating Nonselective Cation Channels through Protein Kinase C in Human Umbilical Vein Endothelial Cells

We analyzed Ca-permeating nonselective cation channels (NSCs)mediating thrombin-induced contraction of human umbilical vein endothelial cells (HUVECs). A Ca chelater, BAPTA-AM (10μM), significantly inhibited the thrombin-induced contraction of HUVECs.Thrombin induced inward currents at -60 mV in the presence of intracellular MgATP. Removal of extracellular Caﾌﾞｸﾞsignificantly decreased the currents. A selective phospholipase C inhibitor, U73122 (1μM) but not its inactive analogue, U73343 (1μM) almost completely inhibited the currents. Neither a selective inhibitor of Caﾌﾞｸﾞ-ATPase of endoplasmic reticulum, thapsigargin (1μM)nor a diacylglycerol analogue, 1-oleoyl-2-acetyl-glycerol (30μM)activated the currents. However, a selective protein kinase C inhibitor, bisindolylmaleimide I (500 nM) significantly inhibited the currents.The thrombin-induced currents were significantly inhibited by SKF96365 (50μM)but not by La(1mM), ruthenium red (10μM) or flufenamic acid (100μM). As assessed with RT-PCR, HUVECs expressed transient receptor potential(TRP)M4,7,TRPV1,2,4,TRPC1,4 and 6 subunits of NSCs.These results indicate that thrombin activates Ca-permeating NSCs containing TRPC4 through protein kinase C in HUVECs. Thus,drugs specifically inhibiting TRPC4-containing channels might be effective to control fatal diseases such as sepsis where thrombin mediates the vicious cycle between inflammation and coagulation.Article信州医学雑誌 59(1): 13-26(2011)departmental bulletin pape

Dosimetric impact of stopping power for human bone porosity with dual-energy computed tomography in scanned carbon-ion therapy treatment planning

Yagi M., Wakisaka Y., Takeno J., et al. Dosimetric impact of stopping power for human bone porosity with dual-energy computed tomography in scanned carbon-ion therapy treatment planning. Scientific Reports 14, 17440 (2024); https://doi.org/10.1038/s41598-024-68312-y.Few reports have documented how the accuracy of stopping power ratio (SPR) prediction for porous bone tissue affects the dose distribution of scanned carbon-ion beam therapy. The estimated SPR based on single-energy computed tomography (SECT) and dual-energy CT (DECT) were compared for the femur of a Rando phantom which simulates the porosity of human bone, NEOBONE which is the hydroxyapatite synthetic bone substitute, and soft tissue samples. Dose differences between SECT and DECT were evaluated for a scanned carbon-ion therapy treatment plan for the Rando phantom. The difference in the water equivalent length was measured to extract the SPR of the examined samples. The differences for SPR estimated from the DECT-SPR conversion were small with − 1.8% and − 3.3% for the Rando phantom femur and NEOBONE, respectively, whereas the differences for SECT-SPR were between 7.6 and 70.7%, illustrating a 1.5-mm shift of the range and a dose difference of 13.3% at maximum point in the evaluation of the dose distribution. This study demonstrated that the DECT-SPR conversion method better estimated the SPR of the porosity of bone tissues than SECT-SPR followed by the accurate range of the carbon-ion beams on carbon-ion dose calculations

Development and characterization of a dedicated dose monitor for ultrahigh-dose-rate scanned carbon-ion beams

Yagi M., Shimizu S., Hamatani N., et al. Development and characterization of a dedicated dose monitor for ultrahigh-dose-rate scanned carbon-ion beams. Scientific Reports 14, 11574 (2024); https://doi.org/10.1038/s41598-024-62148-2.The current monochromatic beam mode (i.e., uHDR irradiation mode) of the scanned carbon-ion beam lacks a dedicated dose monitor, making the beam control challenging. We developed and characterized a dedicated dose monitor for uHDR-scanned carbon-ion beams. Furthermore, a simple measurable dose rate (dose rate per spot (DRspot)) was suggested by using the developed dose monitor and experimentally validating quantities relevant to the uHDR scanned carbon-ion beam. A large plane-parallel ionization chamber (IC) with a smaller electrode spacing was used to reduce uHDR recombination effects, and a dedicated operational amplifier was manufactured for the uHDR-scanned carbon-ion beam. The dose linearity of the IC was within ± 1% in the range of 1.8–12.3 Gy. The spatial inhomogeneity of the dose response of the IC was ± 0.38% inside the ± 40-mm detector area, and a systematic deviation of approximately 2% was measured at the edge of the detector. uHDR irradiation with beam scanning was tested and verified for different doses at the corresponding dose rates (in terms of both the average dose rate and DRspot). We confirmed that the dose monitor can highlight the characteristics (i.e., dose, dose rate, and dose profile) of uHDR-scanned carbon-ion beams at several dose levels in the monochromatic beam mode

High-Speed Terahertz Waveform Measurement for Intense Terahertz Light Using 100-kHz Yb-Doped Fiber Laser

We demonstrate a high-speed terahertz (THz) waveform measurement system for intense THz light with a scan rate of 100 Hz. To realize the high scan rate, a loudspeaker vibrating at 50 Hz is employed to scan the delay time between THz light and electro-optic sampling light. Because the fast scan system requires a high data sampling rate, we develop an Yb-doped fiber laser with a repetition rate of 100 kHz optimized for effective THz light generation with the output electric field of 1 kV/cm. The present system drastically reduces the measurement time of the THz waveform from several minutes to 10 ms