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This study was conducted to clarify the effect of eucalyptus essential oil mixed with milk casein peptide food for human physiological relaxation. Fifteen male university students (21.2 ± 0.9 yr) participated in study as subjects. The subjects were given one of two types of experimental drink (peptide + eucalyptus flavor (Pep + EF), and peptide + grapefruit·orange flavor (Pep + G·O), each flavor contains natural essential oil). We measured the change in salivary cortisol concentration and POMS scores before and two hours after taking experimental drink. The results of a Type A behavior pattern test were used to classify subjects. The concentration of salivary cortisol decreased significantly two hours after taking Pep + EF. And Type B showed bigger change than Type A. In conclusion, the results show that eucalyptus essential oil has the effect of relaxation, and that the effects on Type A and Type B are different.

It is widely believed that coming into contact with forest environments is somehow beneficial to human well-being and comfort. In Japan, âShinrin-yokuâ (taking in the atmosphere of a forest) has been proposed to be a relaxation activity associated with forest recreation. The purpose of this study was to examine the physiological effects of forest recreation on the autonomic nervous activity. The subjects were twelve male university students (21.8 ± 0.8 years old). On the first day of the experiment, six subjects were sent to a forest area, and the other six to a city area. On the second day, each subject was sent to the area he did not visit on the first day as a cross check. The subjects walked (15 minutes) around their assigned areas before noon, and sat on chairs viewing (15 minutes) the landscapes of their assigned areas in the afternoon. Heart rate variability (HRV), blood pressure, and pulse rate were measured as physiological indices. Measurements were taken at the place of accommodation in the morning, before and after walking, and before and after viewing at their assigned field areas. Pulse rate, diastolic blood pressure and LF/(LF+HF) (LF â low frequency, HF â high frequency) components of HRV were significantly lower in the forest area than in the city area. HF components of HRV tended to be higher in the forest than in the city. In conclusion, the results of the physiological measurements show that forest recreation enabled effective relaxation in people, both of the mind and body.

The photocatalytic reduction of carbon dioxide (CO2) represents an attractive approach for solar‐energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible‐light region, a self‐photosensitized, mononuclear Os catalyst for red‐light‐driven CO2 reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP‐type tetradentate ligand resulted in the absorption of light with longer‐wavelength (350–700 nm) and that can be applied to a panchromatic self‐photosensitized catalyst for CO2 reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO2 photoreduction also proceeded under irradiation with blue (λ0=405 nm), green (λ0=525 nm), or red (λ0=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy. [ABSTRACT FROM AUTHOR]

We designed monolithic devices consisting of photovoltaic (PV) modules directly connected to electrochemical (EC) reactor modules for artificial photosynthetic H2 and CO production. Double-junction (2J) PV cells commonly used for this purpose suffer from current mismatching between the top and bottom cells under solar spectrum variation; the detrimental impacts on the solar-to-H2 and -CO energy conversion efficiencies (ηH2 and ηCO, respectively) were found to be more serious than those on solar-to-electricity conversion efficiencies of solar cells connected to power conditioners, because the power conditioners always optimize the operating voltages. To solve this problem, we adopted the combination of a voltage-matched (VM) tandem PV module and an EC module in which multiple EC reactors are series-connected. Parallel connection of the top and bottom PV modules eliminates the current mismatching problem involved in 2J PV cells, while series-connected multiple top PV cells, bottom PV cells, and EC reactors in these modules, respectively, secure voltage matching among these modules. We adopted organic–inorganic hybrid perovskite (PVK) top cells and crystalline silicon (Si) bottom cells according to another design strategy of widespread use. Thus, we modeled the artificial photosynthetic operation of the monolithic devices based on the properties of state-of-the-art PVK and Si PV cells and H2- and CO-producing EC reactors and evaluated annually averaged ηH2 and ηCO. The newly designed monolithic devices using the VM tandem PV modules improve ηH2 compared to those of the conventional devices using 2J PV cells, from 23% to 29%, and ηCO from 23% to 27%. [ABSTRACT FROM AUTHOR]

We applied hot-carrier extraction to particulate photocatalysts for artificial photosynthetic reactions including water splitting for H2 production and CO2 reduction to CO and HCOOH, and elucidated promising features of hot-carrier photocatalysts (HC-PCs). We designed a specific structure of the HC-PC; a semiconductor core in which thermalization of photo-generated carriers is significantly suppressed is surrounded by a shell whose bandgap is wider than that of the core. Among the photo-generated hot carriers in the core, only carriers whose energies are larger than the shell bandgap are extracted passing through the shell to the active sites on the shell surface. Thus, the shell functions as an energy-selective contact. We calculated the upper bounds of the rates of the carrier supply from the core to the active sites using a newly constructed detailed-balance model including partial thermalization and nonradiative recombination of the carriers. It has been revealed that the HC-PCs can yield higher carrier-supply rates and thus potentially higher solar-to-chemical energy conversion efficiencies for H2 and CO production than those of conventional photocatalysts with the assistance of intraband transition and Auger recombination/impact ionization. It should be noted, however, that one of the necessary conditions for efficient hot-carrier extraction is sufficiently large carrier density in the core, which, in turn, requires concentrated solar illumination by several hundreds. This would raise rate-limiting problems of activities of the chemical reactions induced by the photo-generated carriers and material-transfer properties. [ABSTRACT FROM AUTHOR]

A water-soluble Co complex with dimethyl-bipyridine ligands reduced CO2 to CO electrochemically with almost 100% selectivity at −0.80 V vs. NHE in an aqueous medium (pH 6.8) without an organic solvent. The reaction overpotential was 270 mV. A possible CO formation mechanism was discussed based on experiments and calculations. [ABSTRACT FROM AUTHOR]

We have overcome two drawbacks involved in series-connected double-junction (S-2J) and triple-junction (S-3J) photovoltaic cells to compose monolithic modules of artificial photosynthesis consisting of directly connected photovoltaic cells and electrolyzers of the same size. One is current mismatching among the subcells under solar spectrum variation. The other is inefficient utilization of high-energy photons that can generate sufficiently high voltage to promote the target reaction, caused by consumption of two or three photons for extracting a single electron regardless of the photon energies. This arises from the predetermined operating voltage, contrasting to no restriction of the output voltage for solar cells combined with power conditioners. In a series/parallel-connected triple-junction (S/P-3J) photovoltaic cell, the series-connected middle and bottom cells are connected with the top cell in parallel. High-energy photons absorbed in the top cell are efficiently utilized because the photoexcited electrons are directly extracted. Although relative intensities of high-energy photons in the measured solar spectra changes remarkably, the top cell is free from the current matching restriction. On the other hand, current matching between the middle and bottom cells approximately holds, because solar spectrum in the relevant range changes only slightly. Consequently, the S/P-3J significantly improves solar-to-chemical conversion efficiency (ηSTC) and is more advantageous on overcast days owing to the spectral robustness. Using the state-of-the-art electrolyzers, ηSTC = 32%−26% of H2 production by water splitting is estimated on fine and overcast days. CO2 reduction to CO proceeds with ηSTC = 30%−25%. These values are higher than those for the S-2J by 3%−9%. [ABSTRACT FROM AUTHOR]