ABSTRACT
Solar fuels, such as hydrogen gas produced from water and methanol produced from carbon dioxide reduction by artificial photosynthesis, have received considerable attention. In natural leaves the photosynthetic proteins are well-organized in the thylakoid membrane. To develop an artificial leaf device for solar low-carbon fuel production from CO2, a chlorophyll derivative chlorin-e6 (Chl-e6; photosensitizer), 1-carboxylundecanoyl-1'-methyl-4,4'-bipyrizinium bromide, iodide (CH3V(CH2)9COOH; the electron carrier) and formate dehydrogenase (FDH) (the catalyst) immobilised onto a silica-gel-based thin layer chromatography plate (the Chl-V-FDH device) was investigated. From luminescence spectroscopy measurements, the photoexcited triplet state of Chl-e6 was quenched by the CH3V(CH2)9COOH moiety on the device, indicating the photoinduced electron transfer from the photoexcited triplet state of Chl-e6 to the CH3V(CH2)9COOH moiety. When the CO2-saturated sample solution containing NADPH (the electron donor) was flowed onto the Chl-V-FDH device under visible light irradiation, the formic acid concentration increased with increasing irradiation time.
Subject(s)
Biomimetic Materials/analysis , Formate Dehydrogenases/metabolism , Green Chemistry Technology/methods , Photochemistry/methods , Photosynthesis , Porphyrins/chemistry , Solar Energy/statistics & numerical data , Bioelectric Energy Sources , Biofuels , Biomimetic Materials/chemical synthesis , Biomimetic Materials/metabolism , Carbon Dioxide/chemistry , Carbon Dioxide/metabolism , Chlorophyll/chemistry , Chlorophyll/metabolism , Chlorophyllides , Electron Transport , Formate Dehydrogenases/chemistry , Formates/chemical synthesis , Green Chemistry Technology/instrumentation , Hydrogen/chemistry , Hydrogen/metabolism , Light , NADP/chemistry , NADP/metabolism , Oxidation-Reduction , Photochemistry/instrumentation , Photosensitizing Agents , Plant Leaves/chemistry , Plant Leaves/metabolism , Silica Gel/chemistry , Thylakoids/chemistry , Thylakoids/metabolismABSTRACT
The objectives of the work reported in this article were to develop a novel 6-degree-of-freedom (DOC) robotic system for knee joint biomechanics, to complete a hybrid force-position control scheme, to evaluate the system performance, and to demonstrate a combined loading test. The manipulator of the system utilizes two mechanisms; the upper mechanism has two translational axes and three rotational axes while the lower mechanism has only a single translational axis. All axes were driven with AC servo-motors. This unique configuration results in a simple kinematic description of manipulator motion. Jacobian transformation was used to calculate both the displacement and force/moment, which allowed for a hybrid control of the displacement of, and force/moment applied to, the human knee joint. The control and data acquisition were performed on a personal computer in the C-language programming environment with a multi-tasking operating system. Preliminary tests revealed that the clamp-to-clamp compliance of the system was smaller in the vertical (Z) and longitudinal (Y) directions (0.001 mm/N) than in lateral (X) direction (0.003 mm/N). The displacement error under the application of 500 N of load was smallest in the vertical direction (0.001 +/- 0.003 mm (mean +/- SD), and largest in the lateral direction (0.084 +/- 0.027 mm). Using this test system, it was possible to simulate multiple loading conditions in a human knee joint in which a cyclic anterior force was applied together with a coupled, joint compressive force, while allowing natural knee motion. The developed system seems to be a useful tool for studies of knee joint biomechanics.
