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•Zeolite membranes were tested for separation of water in gas phase.•Final target is zeolite membrane reactors for CO2 hydrogenation.•Suitable H2O/H2 separation factors obtained with ...zeolite A membrane.•Preliminary experiments combining traditional reactor with membrane reactor.•Improved yield to methanol using the zeolite membrane reactor.
A zeolite membrane reactor can be employed for hydrogenation of CO2 to methanol. The removal of water from the reaction environment would increase the reaction rate and the achievable conversion. The separation of water from mixtures containing CO2, hydrogen and water at suitable temperatures for this reaction was tested with several zeolite membranes (zeolite A, mordenite, zeolite T, chabazite and Ti-Chabazite). Zeolite A provided the best H2O/H2 separation factor. Preliminary experiments comparing a traditional reactor and the combination of a traditional reactor with a membrane reactor show that the yield of methanol was improved, in one case being higher than the limit corresponding to the thermodynamic equilibrium in a conventional reactor.
In clonal plant populations, a number of genetically identical ramets form a genet. While coexisting ramets potentially perform independently, their behaviours not only depend on ages and sizes but ...are also constrained by genetic background. In this study, genet dynamics and its variability among neighbouring genets were investigated based on the ramet demography of each genet in Convallaria keiskei. Genet dynamics were first formulated as a matrix model with the two components of clonal growth (clonal reproduction) and survival‐transitions between ramet size classes. Then, a statistical estimation of the matrix elements was established using three datasets: aboveground demographic censuses, belowground directional rhizome connections and genetic identification of ramets. Finally, genet growth rates reflecting both the changes of clonal growth and ramet size growth were estimated and compared for fundamental demographic elements among genets. Over three years of aboveground annual censuses of a 28 × 2 m plot, 2021 ramets were identified as belonging to 28 genotypes. Belowground excavation detected 515 clonal fragments. Genet growth rate of three dominant genets varied with medians of 1.13, 1.02 and 1.05; 95% credible intervals of the posterior distributions did not overlap between the genet with the largest median and the others. The variation was caused primarily by differences in clonal growth rather than survival‐transitions between size classes. Clonal growth by branching was rarer than at the tips but contributed to the maintenance of the genet. Therefore, both clonal growth frequencies and connecting patterns of ramets caused the variation of genet dynamics and established genets persist for a long time through the positive growth rates, which would contribute to maintain a population. We also conclude that fundamental demographic elements relating to clonal growth traits (the features of individual genets) strongly impact genet dynamics.
In sessile organisms such as plants, spatial genetic structures of populations show long-lasting patterns. These structures have been analyzed across diverse taxa to understand the processes that ...determine the genetic makeup of organismal populations. For many sessile organisms that mainly propagate via clonal spread, epigenetic status can vary between clonal individuals in the absence of genetic changes. However, fewer previous studies have explored the epigenetic properties in comparison to the genetic properties of natural plant populations. Here, we report the simultaneous evaluation of the spatial structure of genetic and epigenetic variation in a natural population of the clonal plant Cardamine leucantha. We applied a hierarchical Bayesian model to evaluate the effects of membership of a genet (a group of individuals clonally derived from a single seed) and vegetation cover on the epigenetic variation between ramets (clonal plants that are physiologically independent individuals). We sampled 332 ramets in a 20 m × 20 m study plot that contained 137 genets (identified using eight SSR markers). We detected epigenetic variation in DNA methylation at 24 methylation-sensitive amplified fragment length polymorphism (MS-AFLP) loci. There were significant genet effects at all 24 MS-AFLP loci in the distribution of subepiloci. Vegetation cover had no statistically significant effect on variation in the majority of MS-AFLP loci. The spatial aggregation of epigenetic variation is therefore largely explained by the aggregation of ramets that belong to the same genets. By applying hierarchical Bayesian analyses, we successfully identified a number of genet-specific changes in epigenetic status within a natural plant population in a complex context, where genotypes and environmental factors are unevenly distributed. This finding suggests that it requires further studies on the spatial epigenetic structure of natural populations of diverse organisms, particularly for sessile clonal species.
The critical shear stress for dislocation emission at grain boundary was directly measured by nanoindentation technique. The change in the grain boundary strength with low-temperature aging was then ...discussed. It was found that the critical grain boundary shear stress increased, and the increment was correlated to the amount of carbon segregated at the grain boundary. From the relationship between the lower yield point and the amount of segregated carbon, it was concluded that the Hall–Petch coefficient (ky) increased with grain boundary segregation. The validity of the pile-up theory explaining ky, which depends on the grain boundary strength, was demonstrated.
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Abstract
KAGRA is a newly built gravitational-wave telescope, a laser interferometer comprising arms with a length of 3 km, located in Kamioka, Gifu, Japan. KAGRA was constructed under the ground and ...it is operated using cryogenic mirrors that help in reducing the seismic and thermal noise. Both technologies are expected to provide directions for the future of gravitational-wave telescopes. In 2019, KAGRA finished all installations with the designed configuration, which we call the baseline KAGRA. For this occasion, we present an overview of the baseline KAGRA from various viewpoints in a series of articles. In this article, we introduce the design configurations of KAGRA with its historical background.
Lutzomyia longipalpis s.l. is a complex of sibling species and is the principal vector of American visceral leishmaniasis. The present review summarises the diversity of efforts that have been ...undertaken to elucidate the number of unnamed species in this species complex and the phylogenetic relationships among them. A wide variety of evidence, including chemical, behavioral and molecular traits, suggests very recent speciation events and complex population structure in this group. Although significant advances have been achieved to date, differential vector capacity and the correlation between structure of parasite and vector populations have yet to be elucidated. Furthermore, increased knowledge about recent epidemiological changes, such as urbanisation, is essential for pursuing effective strategies for sandfly control in the New World.
Waveforms of vertical electric field observed at distances of 27, 57, and 101 km from the 634‐m tall Tokyo Skytree (Japan) struck by lightning have been reproduced using the 3‐D finite difference ...time domain method. Optically observed 3‐D lightning channels and currents directly measured in the tower were used. Distribution of current along the lightning channel was represented using the transmission line model, assuming a constant propagation speed v = 0.5c. Simulations with commonly assumed vertical channel did not allow us to reproduce the observed early (within 5 μs or so) field zero crossing when the 1‐D speed was set to be constant and equal to the 3‐D speed (v = 0.5c) used for the actual‐channel‐geometry case. It was, however, possible to achieve a good match for a vertical channel when the vertical component of 3‐D speed was evaluated for each nonvertical channel segment and used in the corresponding range of heights.
Plain Language Summary
Since tall towers are often struck by lightning, direct lightning current measurements are usually performed on such towers. Also, lightning strikes to tall towers have been used to test lightning locating systems in terms of their detection efficiency, location accuracy, and current estimation errors. Hence, it is important to study the interaction of lightning with towers and associated electromagnetic fields. In this letter, waveforms of vertical electric field observed at distances of 27, 57, and 101 km from the 634‐m tall Tokyo Skytree struck by lightning have been reproduced using the 3‐D finite difference time domain method. Optically observed 3‐D lightning channels and currents directly measured in the tower were used. Distribution of current along the lightning channel was represented using the transmission line model, assuming a constant propagation speed v = 0.5c. Simulations with commonly assumed vertical channel did not allow us to reproduce the observed field zero crossing when the 1‐D speed was set to be constant and equal to the 3‐D speed (v = 0.5c) used for the actual‐channel‐geometry case. It was, however, possible to achieve a good match for a vertical channel when the vertical component of 3‐D speed was evaluated for each nonvertical channel segment and used in the corresponding range of heights.
Key Points
Lightning strikes to 634‐m Tokyo Skytree are simulated using FDTD, directly measured current, assumed speed, and actual channel geometry
Model‐predicted electric field waveforms at distances of 27, 57, and 101 km from the tower agree well with corresponding measured fields
Simulations with commonly assumed vertical channel and the same constant speed did not yield reproduction of the observed field zero crossing
The evolutionary origins and advantages of clonal reproduction relative to sexual reproduction have been discussed for several taxonomic groups. In particular, organisms with a sessile lifestyle are ...often exposed to spatial and temporal environmental fluctuations. Thus, clonal propagation may be advantageous in such fluctuating environments, for sessile species that can reproduce both sexually and clonally. Here we introduce the concept of niche to a lattice space that changes spatially and temporally, by incorporating the compatibility between the characteristics of a sessile clonal plant with its habitat into a spatially explicit individual-based model. We evaluate the impact of spatially and temporally heterogeneous environments on the evolution of reproductive strategies: the optimal balance between seed and clonal reproduction of a clonal plant. The spatial niche case with local habitats led to avoidance of specialization in reproductive strategy, whereas stable environments or intensive environmental change tended to result in specialization in either clonal or seed reproduction under neutral conditions. Furthermore, an increase in spatial niches made clonal reproduction advantageous, as a consequence of competition among several genets under disturbed conditions, because a ramet reached a favorable habitat through a rare long-distance dispersal event via seed production. Thus, the existence of spatial niches could explain the advantages of clonal propagation.
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