In high-temperature volcanic fumaroles (>400°C), the isotopic composition of molecular hydrogen (H 2 ) reaches equilibrium with that of the fumarolic H 2 O. In this study, we used this hydrogen isotope exchange equilibrium of fumarolic H 2 as a tracer for the remote temperature at volcanic fumaroles. In this remote sensing, we deduced the hydrogen isotopic composition (dD value) of fumarolic H 2 from those in the volcanic plume. To ascertain that we can estimate the dD value of fumarolic H 2 from those in a volcanic plume, we estimated the values in three fumaroles with outlet temperatures of 630°C (Tarumae), 203°C (Kuju), and 107°C (E-san). For this we measured the concentration and dD value of H 2 in each volcanic plume, along with those determined directly at each fumarole. The average and maximum mixing ratios of fumarolic H 2 within a plume's total H 2 were 97% and 99% (at Tarumae), 89% and 96% (at Kuju), and 97% and 99% (at E-san). We found a linear relationship between the depletion in the dD values of H 2 , with the reciprocal of H 2 concentration. Furthermore, the estimated end-member dD value for each H 2 -enriched component (À260 ± 30& vs. VSMOW in Tarumae, À509 ± 23& in Kuju, and À437 ± 14& in E-san) coincided well with those observed at each fumarole (À247.0 ± 0.6& in Tarumae, À527.7 ± 10.1& in Kuju, and À432.1 ± 2.5& in E-san). Moreover, the calculated isotopic temperatures at the fumaroles agreed to within 20°C with the observed outlet temperature at Tarumae and Kuju. We deduced that the dD value of the fumarolic H 2 was quenched within the volcanic plume. This enabled us to remotely estimate these in the fumarole, and thus the outlet temperature of fumaroles, at least for those having the outlet temperatures more than 400°C. By applying this methodology to the volcanic plume emitted from the Crater 1 of Mt. Naka-dake (the volcano Aso) where direct measurement on fumaroles was impractical, we estimated that the dD value of the fumarolic H 2 to be À172 ± 16& and the outlet temperature to be 868 ± 97°C. The remote temperature sensing using hydrogen isotopes developed in this study is widely applicable to many volcanic systems.

The use of probiotics is expected to be an intervention in neurodegenerative conditions that cause dementia owing to their ability to modulate neuroinflammatory responses via the microbiome-gut–brain axis. Therefore, we selected Lactiplantibacillus plantarum OLL2712 (OLL2712), the optimal anti-inflammatory lactic acid bacteria strain with high IL-10-inducing activity in immune cells, and aimed to verify its protective effects on memory function in older adults. A 12-week, randomized, double-blind, placebo-controlled trial was performed with older adults over the age of 65 years with declining memory. The participants consumed either powder containing heat-treated OLL2712 cells or placebo. Memory function was assessed using a computer-assisted cognitive test, Cognitrax. Daily dietary nutrient intake was assessed using the Brief-type Self-administered Diet History Questionnaire (BDHQ). The composition of the gut microbiota was analyzed by fecal DNA extraction and 16S rDNA sequencing. Data from 78 participants who completed the entire procedure were analyzed, and significant improvements in composite memory and visual memory scores were observed in the active group, after accounting for the effect of daily nutritional intake (p = 0.044 and p = 0.021, respectively). In addition, the active group had a lower abundance ratio of Lachnoclostridium, Monoglobus, and Oscillibacter genera, which have been reported to be involved in inflammation. The present study suggests that OLL2712 ingestion has protective effects against memory function decline in older adults.

Since daily dietary habits can affect cognitive function, dietary patterns such as the Mediterranean-DASH Intervention for Neurodegenerative Delay diet have been proposed as interventions to slow cognitive decline. However, because dietary habits vary widely among different food cultures, it is necessary to establish dietary pattern intervention methods that are appropriate for each population. Therefore, in this study, the dietary patterns of elderly Japanese individuals were classified using cluster analysis, and their relationship with cognitive function was investigated. We then modeled the dietary patterns and applied them to another cohort of elderly Japanese individuals to determine whether differences in dietary patterns could predict cognitive decline. One hundred and fifty older adults ≥ 65 years of age in the community were recruited. Their daily food intake and cognitive function were measured using the brief-type self-administered diet history questionnaire and Montreal Cognitive Assessment, respectively. K-means cluster analysis identified a high-carbohydrate (HC) dietary pattern with high cereal intake and a protein-balanced (PB) dietary pattern with high intake of legumes, vegetables, seafood, meat, and eggs. Cognitive function was significantly higher in the PB group than in the HC group. Furthermore, to classify the new data into HC and PB patterns, a classification model was created by discriminant analysis using food groups with significantly different intakes among dietary patterns. Next, we recruited 267 new older adults ≥ 65 years of age and measured food intake and cognitive function assessed using the memory performance index score. Individuals with cognitive decline were identified and their detailed cognitive functions were assessed using the neurocognitive index score. Cognitive function was significantly impaired in the HC pattern in both the general elderly and cognitively impaired cohorts. These findings suggest that a dietary pattern of low carbohydrate and high protein intake is associated with good cognitive function in elderly Japanese individuals. Classification by these dietary patterns can predict cognitive reservation in community-dwelling older adults.