Printable elastic conductors promise large-area stretchable sensor/actuator networks for healthcare, wearables and robotics. Elastomers with metal nanoparticles are one of the best approaches to ...achieve high performance, but large-area utilization is limited by difficulties in their processability. Here we report a printable elastic conductor containing Ag nanoparticles that are formed in situ, solely by mixing micrometre-sized Ag flakes, fluorine rubbers, and surfactant. Our printable elastic composites exhibit conductivity higher than 4,000 S cm
(highest value: 6,168 S cm
) at 0% strain, and 935 S cm
when stretched up to 400%. Ag nanoparticle formation is influenced by the surfactant, heating processes, and elastomer molecular weight, resulting in a drastic improvement of conductivity. Fully printed sensor networks for stretchable robots are demonstrated, sensing pressure and temperature accurately, even when stretched over 250%.
Hunting affects a considerably greater area of the tropical forest biome than deforestation and logging combined. Often even large remote protected areas are depleted of a substantial proportion of ...their vertebrate fauna. However, understanding of the long‐term ecological consequences of defaunation in tropical forests remains poor. Using tree census data from a large‐scale plot monitored over a 15‐year period since the approximate onset of intense hunting, we provide a comprehensive assessment of the immediate consequences of defaunation for a tropical tree community. Our data strongly suggest that over‐hunting has engendered pervasive changes in tree population spatial structure and dynamics, leading to a consistent decline in local tree diversity over time. However, we do not find any support for suggestions that over‐hunting reduces above‐ground biomass or biomass accumulation rate in this forest. To maintain critical ecosystem processes in tropical forests increased efforts are required to protect and restore wildlife populations.
Seed dispersal by birds is critical for regeneration and maintenance of plant populations. Birds likely rely on both visible light of human's eyes and ultraviolet (UV) reflectance when foraging for ...fruit. Fruit color is suggested to be an honest signal that allows birds to assess nutrient status. We assessed UV reflectance and pericarp color as honest indicators of fruit maturity in three fruiting shrubs in Osaka, Japan. We measured sugar content and light spectra in the fruits of Eurya japonica, Ligustrum obtusifolium and Ligustrum japonicum and observed birds foraging on target individuals. We found that a model including fruit color and UV reflection as explanatory variables best explained variation in fruit sugar content in E. japonica and L. obtusifolium, whereas UV reflection alone best explained variation in L. japonicum. Next, we assessed relationships between fruit color and bird foraging behavior and found strong temporal correlation between active foraging and peak sugar content. Bird foraging behavior differed among the three shrub species. This is probably because fruit consumption by birds is not entirely dependent on fruit color or sugar content of the fruits. It must depend on various factors such as the presence of fruiting neighbors of conspecific or heterospecific plants and seasonal variation of population-level or community-level fruit abundance.
The present study aimed to evaluate suitable protein sources of formulated diet to replace prey fish. Regarding the test diet, the two dietary treatments (FM: Peruvian anchovy fish meal, and ETFM: ...enzyme-treated Chilean fish meal) were employed. Prey fish (PF; spangled emperor fish
Lethrinus nebulosus
) was used as a control. FM and ETFM diets are fed together with a limited amount of PF to Pacific bluefin tuna (PBT) larvae having an initial mean total length of 17.9 mm and body weight of 52.8 mg at 20 days post-hatching during the weaning period. Survival and growth were compared after 10 days of the feeding trial. Survival was significantly higher in the PF group than the FM and ETFM group. The PF group had significantly greater growth performance than the other groups. Between FM and ETFM groups, fish in the FM group showed significantly better growth than the ETFM group. Regarding the essential amino acids of the carcass, similar amino acid content was recorded in all treatments. However, carcass docosahexaenoic acid in the PF group was significantly higher than in the other groups. These results suggest that Peruvian anchovy meal without enzyme digestion can be used as the protein source in the formulated diet for juvenile PBT.
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Bilirubin oxidase (BOD) is a bioelectrocatalyst that reduces dioxygen (O2) to water and is capable of direct electron transfer (DET)-type bioelectrocatalysis via its electrode-active ...site (T1 Cu). BOD from Myrothecium verrucaria (mBOD) has been widely studied and has strong DET activity. mBOD contains two N-linked glycans (N-glycans) with N472 and N482 binding sites distal to T1 Cu. We previously reported that different N-glycan compositions affect the enzymatic orientation on the electrode by using recombinant BOD expressed in Pichia pastoris and the deglycosylation method. However, the individual function of the two N-glycans and the effects of N-glycan composition (size, structure, and non-reducing termini) on DET-type reactions are still unclear. In this study, we utilize maleimide-functionalized polyethylene glycol (MAL-PEG) as an N-glycan mimic to evaluate the aforementioned effects. Site-specific enzyme-PEG crosslinking was carried out by specific binding of maleimide to Cys residues. Recombinant BOD expressed in Escherichia coli (eBOD), which does not have a glycosylation system, was used as a benchmark to evaluate the effect. Site-directed mutagenesis of Asn residue (N472 or N482) into Cys residue is utilized to realize site-specific glycan mimic modification to the original binding site.
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•Effect of N-linked glycans on DET-type bioelectrocatalysis was investigated.•Two types of bilirubin oxidases and their deglycosylated forms were used.•Most favorable orientation was ...achieved with largest and complex N-linked glycans.•Interaction of N-linked glycans with electrodes is an important factor.
Bilirubin oxidase from Myrothecium verrucaria (mBOD) is a promising enzyme for catalyzing the four-electron reduction of dioxygen into water and realizes direct electron transfer (DET)-type bioelectrocatalysis. It has two N-linked glycans (N-glycans), and N472 and N482 are known as binding sites. Both binding sites located on opposite side of the type I (T1) Cu, which is the electrode-active site of BOD. We investigated the effect of N-glycans on DET-type bioelectrocatalysis by performing electrochemical measurements using electrodes with controlled surface charges. Two types of BODs with different N-glycans, mBOD and recombinant BOD overexpressed in Pichia pastoris (pBOD), and their deglycosylated forms (dg-mBOD and dg-pBOD) were used in this study. Kinetic analysis of the steady-state catalytic waves revealed that both size and composition of N-glycans affected the orientation of adsorbed BODs on the electrodes. Interestingly, the most favorable orientation was achieved with pBOD, which has the largest N-glycans. Furthermore, the effect of the orientation control by the N-glycans is cooperative with electrostatic interaction.
The reproductive capacities of dioecious plant species may be limited by severe pollen limitation and narrow seed shadows for the two reasons. First, they are unable to self‐pollinate, and seed ...production occurs only with pollinator movement from males to females. Second, only 50% of the individuals in populations contribute to seed production. Despite these handicaps, dioecious plants maintain their populations in plant communities with cooccurring cosexual plants, and no substantial difference in population growth rates has been found between dioecious and cosexual plants. Hence, dioecious plants are thought to mitigate these disadvantages by adopting ecological traits, such as insect pollination, animal‐dispersed fleshy fruits, and precocious flowering. We studied the relationship between flowering and plant size in 30 woody species with different sex expressions, leaf habits, fruit types, and maximum plant sizes. The study site was located in an evergreen broad‐leaved forest on the island of Honshu, Japan. A phylogenetic linear regression model showed that dioecious species tended to mature at smaller sizes than did cosexual taxa. At the population level, given equal plant densities and reproductive efforts, the precocity of dioecious plants could serve as one of the factors that mitigate the limitations of pollen and seed‐shadow handicaps by increasing the density of reproductive individuals in the population. At the individual level, smaller size of onset of flowering may play a role in enhancing reproductive success over a lifetime by increasing reproductive opportunities. We discussed the possible effect of the relationship between precocity and some ecological traits of dioecious plants, such as small flowers pollinated by unspecialized insects, fleshy fruit dispersed by animals, and their preferential occurrence in the tropics and in island habitats. The universality of precocity among dioecious plants should be investigated in diverse plant communities. Such studies will increase our understanding of the evolution of plant breeding systems.
We studied the relationship between flowering and plant size in 30 woody species with different sex expressions, leaf habits, fruit types, and maximum plant sizes. Dioecious species tended to mature at a smaller size than did cosexual taxa. The precocity of dioecious plants should mitigate their reproductive disadvantages, i.e., pollen limitation and seed‐shadow handicaps.
Research Highlights: genetic diversity in populations were compared among related shrub species with different reproductive systems. Background and Objectives: Lindera species are dioecious trees or ...shrubs that produce seeds by mating of males and females. To evaluate the importance of genetic diversity for the persistence of natural populations, we compared genetic information among four Lindera species in Japan. Three are dioecious shrubs (Lindera praecox, Lindera umbellata, and Lindera obtusiloba) that produce seeds by sexual reproduction. The remaining species, Lindera glauca, reproduces by apomixis; only female plants are found in Japan. Materials and Methods: all four species were sampled across a wide geographic area, from Tohoku to Kyushu, Japan. Single nucleotide polymorphisms (SNPs) were detected by multiplexed ISSR genotyping by sequencing (MIG-seq) and the resulting genetic diversity parameters were compared among populations. Results: in all sexually reproducing species, the values of observed heterozygosity were close to the expected ones and the inbreeding coefficients were nearly 0. These results were supposed to be caused by their obligate outcrossing. The genetic difference increased, in ascending order, between a mother plant and its seeds, within populations, and across geographic space. We observed a substantial geographic component in the genetic structure of these species. For L. glauca, the genetic difference between a mother and its seeds, within populations, and across space were not significantly different from what would be expected from PCR errors. Genetic diversity within and among populations of L. glauca was extremely low. Conclusions: apomixis has the advantage of being able to found populations from a single individual, without mating, which may outweigh the disadvantages associated with the extremely low genetic diversity of L. glauca. This may explain why this species is so widely distributed in Japan. Provided that the current genotypes remain suited to environmental conditions, L. glauca may not be constrained by its limited genetic diversity.
The structures and electronic states in all polymorphs of poly(vinylidene fluoride) (PVDF) were calculated by density functional theory with the generalized gradient approximation combined with ...Hartee-Fock exchange energy at the Perdew-Burke-Ernzerhof zero-parameter hybrid functional level using the CRYSTAL 09 software. The calculated lattice constants agreed well with experimental values. Derived electronic and phonon dispersions correspond closely with the experimental valence X-ray photoelectron and infrared (IR)/Raman spectra, respectively. The amount of spontaneous polarization in polar crystal forms was determined and the effect of long-range Coulomb interactions were discussed. The calculation method used in this report was confirmed to be precise and shows promise for examining ferroelectric polymers.
Hybridization between the introduced and native plants may enhance invasiveness, especially in asexually reproducing species. Hybrid apomictic dandelions between native (
Taraxacum platycarpum
and
T. ...japonicum
) and exotic (
T. officinale
) species are distributed widely throughout Japan. To estimate the origin(s) and dispersal of the hybrids, we investigated the hybridization rate and genotypic diversity in mixed populations of
T. japonicum, T. officinale
and their hybrids at two green parks in western Japan. Among the plants identified as exotics from flower morphology, 86–96% were hybrids by genetic analysis. Genetic data with simple sequence repeat markers revealed a high clonal diversity of the hybrid both within and between populations, indicating multiple origins. A hybrid seed was found from among the 1891 seeds collected from
T. japonicum
in the parks, indicating ongoing hybridization in the field.
T. officinale
and hybrids were genetically differentiated between the two parks independent of the ploidy level; the allele frequency of
T. officinale
and tri- and tetraploid hybrids were similar within each park but different between the two parks. This suggests that the origins of hybrids were similar within the park but different between the parks. Overall, our results suggest that hybridization, including backcross, is an ongoing process, and that genetically diverse hybrids with various origins have been spreading in western Japan, probably because hybridization enhanced invasiveness at native habitat.
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