Strategies to enhance the excitation energy-transfer efficiency in a light-harvesting system using the intra-molecular charge transfer character of carotenoids

Fucoxanthin is a carotenoid that is mainly found in light-harvesting complexes from brown algae and diatoms. Due to the presence of a carbonyl group attached to polyene chains in polar environments, excitation produces an excited intra-molecular charge transfer. This intra-molecular charge transfer state plays a key role in the highly efficient (∼95%) energy-transfer from fucoxanthin to chlorophyll a in the light-harvesting complexes from brown algae. In purple bacterial light-harvesting systems the efficiency of excitation energy-transfer from carotenoids to bacteriochlorophylls depends on the extent of conjugation of the carotenoids. In this study we were successful, for the first time, in incorporating fucoxanthin into a light-harvesting complex 1 from the purple photosynthetic bacterium, Rhodospirillum rubrum G9+ (a carotenoidless strain). Femtosecond pump-probe spectroscopy was applied to this reconstituted light-harvesting complex in order to determine the efficiency of excitation energy-transfer from fucoxanthin to bacteriochlorophyll a when they are bound to the light-harvesting 1 apo-proteins

Relationship between risk information on total colonoscopy and patient preferences for colorectal cancer screening options: Analysis using the Analytic Hierarchy Process

<p>Abstract</p> <p>Background</p> <p>Although the fecal occult blood test (FOBT) is the preferred program for colorectal cancer screening in Japan, many medical institutions have recently begun to provide total colonoscopy (TCS) as an initial screening program. However, there are a number of severe risks associated with TCS, such as colorectal bleeding and perforation. The justification for performing such a procedure on healthy patients remains unclear. We used the analytic hierarchy process (AHP) to investigate whether risk information on TCS affects patient preferences for colorectal cancer screening.</p> <p>Methods</p> <p>We performed a questionnaire survey using an AHP decision-making model, targeting 285 people aged 40–59 years. We randomly assigned the subjects into Groups A (n = 146) and B (n = 139). Both groups were provided with information on the effectiveness, cost and disadvantages of the two screening programs. Group A was provided with additional information regarding the risks of TCS. Individual priorities were calculated with pair-wise comparisons between the two alternatives in each selection criteria. The influence of the risk information was analyzed using a logistic regression analysis.</p> <p>Results</p> <p>The aggregated priorities in Group A for 'effectiveness', 'costs', and 'risks' were 0.603, 0.147, and 0.250, respectively, while those in Group B were 0.652, 0.149, and 0.199, respectively. A logistic regression analysis showed that the provision of risk information significantly reduced the subjects' priorities for TCS (p = 0.036).</p> <p>Conclusion</p> <p>The lack of risk information was related to the differences in priorities assigned to effectiveness and risks of the two procedures. Patients must be well informed before making decisions concerning their preferred colorectal cancer screening procedure.</p

In-Orbit Performance of the GRACE Follow-on Laser Ranging Interferometer

The Laser Ranging Interferometer (LRI) instrument on the Gravity Recovery and Climate Experiment (GRACE) Follow-On mission has provided the first laser interferometric range measurements between remote spacecraft, separated by approximately 220 km. Autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degrees of freedom two-way laser link between remote spacecraft succeeded on the first attempt. Active beam pointing based on differential wave front sensing compensates spacecraft attitude fluctuations. The LRI has operated continuously without breaks in phase tracking for more than 50 days, and has shown biased range measurements similar to the primary ranging instrument based on microwaves, but with much less noise at a level of 1 nm/Hz at Fourier frequencies above 100 mHz. © 2019 authors. Published by the American Physical Society

Formation of Tc(IV) Oxide Colloids by Bremsstrahlung Irradiation of Aqueous Solutions of Pertechnetate(II. Radiochemistry)

Technetium(IV) oxide colloids (TcO_2・nH_2O) were formed by bremsstrahlung irradiation of aqueous solutions of pertechnetate (TcO_4^-). A transmission electron microscopy (TEM) analysis showed that the size of colloids distributed around 30 to 130 nm in diameter. The characteristic X-rays from technetium and oxygen were detected from colloid particles at the TEM measurements. Round-shaped colloids were produced by the irradiation at 40℃, whereas irregular-shaped colloid particles composed of tiny particles (2 nm in diameter) were produced at 17℃. The concentration of TcO_4^- in the target solution decreased with an increase of the absorbed dose, corresponding to an increase of the colloids yield. The yield of colloids sharply increased in the solution deaerated by Ar bubbling before irradiation, but strongly suppressed in the solution saturated with oxygen (O_2) or nitrous oxide (N_2O) gas. The fact suggests that hydrated electrons play an important role in the course of the reduction of TcO_4^- and that Tc(IV) oxide colloid is formed via successive disproportionation reactions of Tc(VI) and Tc(V)

Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution-2: Effects of nuclear fragmentation and its simulation with PHITS

The G(OH) values in aqueous coumarin-3-carboxylic-acid (3-CCA) solutions irradiated with (12)C(6+) beams having the energies of 135, 290 and 400 MeV/u were measured by a fluorescent method around the Bragg peak, with 0.6 mm intervals, and quartz cells of 1 cm optical lengths, at the Heavy Ion Medical Accelerator in Chiba, National Institute of Radiological Sciences (NIRS). For each ion, the G(OH) has been calculated as a function of dose average LET and position. The calculated results have been compared to measurements, and the results, reproducibility and reliability of the calculations are discussed in the paper