We investigated biofilm formation on biodegradable plastics in freshwater samples. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) was covered by a biofilm after an incubation in freshwater ...samples. A next generation sequencing analysis of the bacterial communities of biofilms that formed on PHBH films revealed the dominance of the order Burkholderiales. Furthermore, Acidovorax and Undibacterium were the predominant genera in most biofilms. Twenty-five out of 28 PHBH-degrading isolates were assigned to the genus Acidovorax, while the other three were assigned to the genera Undibacterium and Chitinimonas. These results demonstrated that the order Burkholderiales in biofilms functions as a degrader of PHBH films.
Polyhydroxyalkanoate (PHA) is a biodegradable polymer that is synthesized by a wide range of microorganisms. One of the derivatives of PHA, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) has ...flexible material properties and low melting temperature. We have previously demonstrated that PHBH is degradable in a freshwater environment via the formation of biofilm on the surface of the PHBH film. Undibacterium sp. KW1 and YM2, which were isolated from the biofilm present on the PHBH film in the freshwater sample, were shown to have PHBH-degrading activity. In this study, the complete genome sequence of KW1 and YM2 revealed that the extracellular PHA depolymerase gene, designated as phaZUD, was present in their chromosomes. Sequence analysis revealed that PhaZUD contained four domains: a signal peptide, catalytic domain, linker domain, and substrate-binding domain. Escherichia coli harboring a PhaZUD-expressing plasmid showed PHBH-degrading activity in LB medium containing 1 wt% PHBH powder. The recombinant His-tagged PhaZUD from KW1 and YM2 was purified from the culture supernatant and shown to have PHBH-degrading activity at the optimum temperature of 35 and 40°C, respectively. When the degradation product in the PHBH solution was treated with PhaZUD and assayed by LC-TOF-MS, we detected various oligomer structures, but no more than pentamers, which consist of 3-hydroxybutyrate and 3-hydroxyhexanoate. These results demonstrated that PhaZUD may have an endo-type extracellular PHA depolymerase activity.
Coastal wetlands such as salt marshes and mangroves provide valuable ecosystem services including coastal protection. Many studies have assessed the influence of plant traits and wave conditions on ...vegetation-induced wave dissipation, whereas the effect of tidal currents is often ignored. To our knowledge, only two studies investigated wave dissipation by vegetation with the presence of following currents (current velocity is in the same direction as wave propagation) (Li and Yan, 2007; Paul et al., 2012). However, based on independent experiments, they have drawn contradictive conclusions whether steady currents increase or decrease wave attenuation. We show in this paper that this inconsistency may be caused by a difference in ratio of imposed current velocity to amplitude of the horizontal wave orbital velocity. We found that following currents can either increase or decrease wave dissipation depending on the velocity ratio, which explains the seeming inconsistency in the two previous studies. Wave dissipation in plant canopies is closely related to vegetation drag coefficients. We apply a new approach to obtain the drag coefficients. This new method eliminates the potential errors that are often introduced by the commonly used method. More importantly, it is capable of obtaining the vegetation drag coefficient in combined current–wave flows, which is not possible for the commonly used calibration method. Based on laboratory data, we propose an empirical relation between drag coefficient and Reynolds number, which can be useful for numerical modeling. The characteristics of drag coefficient variation and in-canopy velocity dynamics are incorporated into an analytical model to help understand the effect of following currents on vegetation-induced wave dissipation.
•Steady currents can either enhance or suppress vegetation-induced wave dissipation•An model was proposed to understand wave dissipation with co-occurring currents•A new method was applied to obtain vegetation drag coefficients•Co-occurring currents decrease vegetation drag coefficients•Wave-induced mean velocity is important in understanding wave dissipation
A new wave-vegetation model is implemented in an open-source code, SWASH (Simulating WAves till SHore). The governing equations are the nonlinear shallow water equations, including non-hydrostatic ...pressure. Besides the commonly considered drag force induced by vertical vegetation cylinders, drag force induced by horizontal vegetation cylinders in complex mangrove root systems, as well as porosity and inertia effects, are included in the vegetation model, providing a logical supplement to the existing models. The vegetation model is tested against lab measurements and existing models. Good model performance is found in simulating wave height distribution and maximum water level in vegetation fields. The relevance of including the additional effects is demonstrated by illustrative model runs. We show that the difference between vertical and horizontal vegetation cylinders in wave dissipation is larger when exposed to shorter waves, because in these wave conditions the vertical component of orbital velocity is more prominent. Both porosity and inertia effects are more pronounced with higher vegetation density. Porosity effects can cause wave reflection and lead to reduced wave height in and behind vegetation fields, while inertia force leads to negative energy dissipation that reduces the wave-damping capacity of vegetation. Overall, the inclusion of both effects leads to greater wave reduction compared to common modeling practice that ignores these effects, but the maximum water level is increased due to porosity. With good model performance and extended functions, the new vegetation model in SWASH code is a solid advancement toward refined simulation of wave propagation over vegetation fields.
•A new wave-vegetation interaction model is implemented in the open-source SWASH code.•Good model performance is obtained compared to lab data and existing models.•Horizontal vegetation cylinders induce higher wave dissipation in shorter waves.•Porosity leads to wave reflection and reduced wave transmission in dense vegetation.•Inertia can induce a noticeable influence on wave propagation when density is high.
This paper analyses the effect of vegetation on wave damping under severe storm conditions, based on a combination of field measurements and numerical modelling. The field measurements of wave ...attenuation by vegetation were performed on two salt marshes with two representative but contrasting coastal wetland vegetation types: cordgrass (Spartina anglica) and grassweed (Scirpus maritimus). The former is found in salty environments, whereas the latter is found in brackish environments. The measurements have added to the range with the highest water depths and wave heights presented in the literature so far. A numerical wave model (SWAN) has been calibrated and validated using the new field data. It appeared that the model was well capable of reproducing the observed decay in wave height over the salt marsh. The model has been applied to compute the reduction of the incident wave height on a dike for various realistic foreshore configurations and hydraulic loading conditions. Additionally, the efficiency of vegetated foreshores in reducing wave loads on the dike has been investigated, where wave loads were quantified using a computed wave run-up height and wave overtopping discharge. The outcomes show that vegetated foreshores reduce wave loads on coastal dikes significantly, also for the large inundation depths that occur during storms and with the vegetation being in winter state. The effect of the foreshore on the wave loads varies with wave height to water depth ratio on the foreshore. The presence of vegetation on the foreshore extends the range of water depths for which a foreshore can be applied for effective reduction of wave loads, and prevents intense wave breaking on the foreshore to occur. This research demonstrates that vegetated foreshores can be considered as a promising supplement to conventional engineering methods for dike reinforcement.
•Field measurements of wave energy dissipation on salt marshes under storm conditions•Calibration and validation of the SWAN wave model including vegetation•Analysis of wave dissipation mechanisms on vegetated foreshores•Assessment of the efficiency of vegetated foreshores for reducing wave loads on coastal dikes
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For the efficient and stable electrochemical reduction of carbon dioxide (CO2), we fabricated bimetallic catalysts composed of palladium (Pd) nanoparticles covered with copper (Cu) ...atomic layers. While a monometallic Pd nanoparticle catalyst has high activity toward the reduction of CO2 to formate, it has been reported to be readily subjected to self-poisoning by carbon monoxide (CO), which is produced as a minor byproduct of CO2 reduction. Cu layers prepared by underpotential deposition induced charge transfer from Pd to Cu and a downward shift of the average d-band center of the catalyst relative to the Fermi level. As a result, the Cu-modified Pd catalyst demonstrated improved CO tolerance and an increase in Faradaic efficiency for formate production without sacrificing CO2 reduction activity.
The individual physical appearances of robots are considered significant, similar to the way that those of humans are. We investigated whether users prefer robots with male or female physical ...appearances for use in daily communication situations and whether egalitarian gender role attitudes are related to this preference. One thousand adult men and women aged 20–60 participated in the questionnaire survey. The results of our study showed that in most situations and for most subjects, “males” was not selected and “females” or “neither” was selected. Moreover, the number of respondents who chose “either” was higher than that who chose “female.” Furthermore, we examined the relationship between gender and gender preference and confirmed that the effect of gender on the gender preference for a robot weakened when the human factor was eliminated. In addition, in some situations for android-type robots and in all situations for machine-type robots, equality orientation in gender role attitudes was shown to be higher for people who were not specific about their gender preferences. It is concluded that there is no need to introduce a robot that specifies its gender. Robots with a gender-neutral appearance might be more appropriate for applications requiring complex human–robot interaction and help avoid reproducing a gender bias.
Plant diseases caused by the Cercospora genus of ascomycete fungi are a major concern for commercial agricultural practices. Several Cercospora species can affect soybeans, such as Cercospora ...kikuchii which causes soybean leaf blight. Speciation in Cercospora on soybean has not been adequately studied. Some cryptic groups of Cercospora also cause diseases on soybean. Moreover, it has been known C. kikuchii population genetic structure is different between countries. Consequently, further genomic information could help to elucidate the covert differentiation of Cercospora diseases in soybean. Here, we report for the first time, a chromosome-level genome assembly for C. kikuchii. The genome assembly of 9 contigs was 34.44 Mb and the N50 was 4.19 Mb. Based on ab initio gene prediction, several candidates for pathogenicity-related genes, including 242 genes for putative effectors, 55 secondary metabolite gene clusters, and 399 carbohydrate-active enzyme genes were identified. The genome sequence and the features described in this study provide a solid foundation for comparative and evolutionary genomic analysis for Cercospora species that cause soybean diseases worldwide.
Although existing studies have suggested that gender stereotypes affect human perceptions about robots, neither what type of robot tasks or roles are expected to show gender characteristics nor ...whether expected gender characteristics are directly related to conventional gender conceptions have been sufficiently investigated. To explore these issues, this study conducted two online surveys. In the first survey (
N
= 500) a total of 30 items related to interaction scenes asked whether male, female, or neutral gender was preferred in terms of the appearance of communication partners in these scenes, and five categories regarding the roles and tasks of robots were extracted based on expected gender appearances. The results revealed a weak effect showing higher gender conceptions inviting a female gender appearance preference in some categories. The second survey (
N
= 400) measured participants’ gender conception, negative attitudes toward robots, gender appearance preferences for the categories of robot roles and tasks extracted in the first survey, and occupations to investigate relationships between them. The results revealed that the influence of gender stereotypes and negative attitudes toward robots on gender appearance preferences changed depending on human occupation, in particular, those with the occupations of counselor, adviser, nurse, and caregiver were not associated with stereotypes, attitudes, or gender preferences toward robots playing roles in their own field of expertise.
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