Biodiversity and spatial distribution of ascidian using environmental DNA metabarcoding.

Monitoring studies are necessary to understand the biodiversity of marine ecosystems and are useful for identifying and managing rare or invasive species. Because monitoring has traditionally relied only on visual surveys (e.g., trapping, netting, electrofishing, and SCUBA diving) with limited time and physical resources, environmental DNA (eDNA) analysis is being applied as an efficient monitoring method. This study compared whether the eDNA metabarcoding technique can replace the traditional visual survey in an ascidian fauna study. We designed ascidian-specific primers and identified a clear gap (3.75%) by barcoding gap analysis. Then, we collected seawater samples for eDNA analysis during the summer (August-September) of 2021 at three sites (Mokpo, Yeosu, and Uljin) in South Korea. In the survey sites of this study, 25 species were observed through literature and visual survey, among which 9 species were detected by metabarcoding and 16 species were not detected. On the other hand, 10 species were detected only by metabarcoding, and one of them was identified as Pyura mirabilis, an unrecorded species in South Korea. This study succeeded in detecting cryptic or rare species with one seawater collection, which can be used to determine their unexplored habitat. Therefore, we conclude that monitoring using eDNA is more efficient than visual surveys for detecting rare or cryptic ascidian species. We also suggest that, when combined with traditional monitoring methods, it could be a tool to complement ascidian fauna studies.

Antifouling Effects of Superhydrophobic Coating on Sessile Marine Invertebrates.

Biofouling is a significant problem in the aquaculture and marine shipping industries; thus, various antifouling methods have been developed to prevent the resultant economic losses. In the present study, the superhydrophobic surface of a lotus leaf was bio-mimicked to achieve antifouling. Specifically, fabric substrates with and without superhydrophobic coatings on the surface were installed on the Tongyeong yacht in December 2020 (group A) and April 2021 (group B), and the coverage of the attached invertebrates was recorded every month until August 2021. The coverage of solitary ascidians (Ascidiella aspersa and Ciona robusta) and branching bryozoans (Bugula neritina) was lower on the coated substrates than on the non-coated ones, and coating or non-coating was significantly correlated with the extent of coverage. Superhydrophobic substrates with a low surface energy and micro-nano dual structure may be unsuitable for the attachment of larvae. Therefore, superhydrophobic coating is a more effective and simpler method of antifouling for certain taxa than other antifouling strategies. However, the antifouling effect of the superhydrophobic substrate in group A reduced after 5 months from the first installation; thus, the durability of the antifouling coating should be further improved, and solving this problem remains a major task, necessitating further research.

Comparison of Recruitment Patterns of Sessile Marine Invertebrates According to Substrate Characteristics.

A community of benthic invertebrates, including sessile adult-stage invertebrates, can negatively effect corrosion, deformation, and increased fuel consumption by attaching to artificial structures, a phenomenon known as marine biofouling. Investigating the relationship between benthic communities and artificial structures or substrates (to which the organisms attach) can help clarify the factors influencing marine biofouling. Therefore, in our study, natural (stone) and artificial (rubber, tarpaulin, and iron) substrates were installed in three harbors (Mokpo, Tongyeong, and Busan), and the structures of the communities attached to each substrate were compared. The total study period was 15 months (September 2016 to December 2017), and field surveys were performed at 3-month intervals. The three survey sites had significant differences in the structure of the sessile community present. In particular, Tongyeong was significantly different from Mokpo and Busan due to the continuous dominance of Cirripedia. When comparing natural and artificial substrate by sites, significant differences were observed in the community structure in all three surveyed sites. In Mokpo and Busan, colonial ascidians were dominant on natural substrate rather than artificial substrates; post-summer, Cirripedia coverage was higher on artificial substrates than natural substrate due to corrosion. Tongyeong showed a different pattern from that of Mokpo and Busan. After the summer, Bivalvia dominated on natural substrate over artificial substrates, affecting the differences between natural and artificial substrates. Our results demonstrate the recruitment patterns of sessile marine invertebrates according to substrate characteristics and can be used as basic information for biofouling management in marine environment.

The complete mitochondrial genome of Balanus trigonus (Thecostraca, Balanomorpha, Balanidae) from South Korea.

The complete sequence of the mitochondrial genome of Balanus trigonus Darwin, 1854 was examined using next-generation sequencing analysis. The complete mitogenome of B. trigonus has 15,336 bp in length and comprises 37 genes, namely, 13 protein-coding genes (PCGs), 22 tRNAs, and two rRNAs. Both the gene order and characteristics are consistent with those of other species within the family Balanidae. Phylogenetic analysis based on complete mitogenomes revealed taxonomic relationships among members of the family Balanidae.

Hazard potential of perovskite solar cell technology for potential implementation of "safe-by-design" approach.

The perovskite solar cell (PSC) is a rapidly advancing solar technology with high efficiencies and low production costs. However, as the PSC contains methylammonium lead iodide (CH3NH3PbI3, MAPbI3) in the light-harvesting active layer, addressing the safety issue of PSCs is an important prerequisite for its commercialization. In this study, the potential hazards of the PSC were investigated with consideration of Pb species released from PSC using an ecotoxicity, cytotoxicity, chronic toxicity, and genotoxicity battery assay. PSC and its degradation products can cause significant toxicity, with PSC being more toxic than the individual degradation products. The order of ecotoxicity and cytotoxicity was found to be Pb2+ > PSC > PbI2 = PbO. Aquatic toxicity of PSC and its degradation products was suggested by Daphnia magna acute, chronic, and genotoxicity results. The current study highlights the non-negligible hazard potentialities of the PSC and its degradation products, as evidenced by our ecotoxicity and cytotoxicity battery assay. Our study indicates that great caution should be taken in the mass production of PSCs and could facilitate proper risk assessment. Based on our study, some considerations on the implementation of the "safe-by-design (SbD)" approach for the sustainable development of PSC technology can be formulated.

A platinum catalyst deposited on a zirconia support for the design of lithium-oxygen batteries with enhanced cycling ability.

A platinum catalyst supported on zirconia is proposed as a cathode in lithium-oxygen batteries. Experimental and theoretical studies show that zirconia suppresses the side-reactions of the intermediate (O2-) and the final product (Li2O2) by the stabilization of their reactivity. Thus, it is able to enhance the reversibility during charge/discharge in lithium-oxygen batteries.

Correction: Observation of crystalline changes of titanium dioxide during lithium insertion by visible spectrum analysis.

Correction for 'Observation of crystalline changes of titanium dioxide during lithium insertion by visible spectrum analysis' by Inho Nam et al., Phys. Chem. Chem. Phys., 2017, 19, 13140-13146.

Observation of crystalline changes of titanium dioxide during lithium insertion by visible spectrum analysis.

Real-time analysis of changes in the atomic environment of materials is a cutting edge technology that is being used to explain reaction dynamics in many fields of science. Previously, this kind of analysis was only possible using heavy nucleonic equipment such as XANES and EXAFS, or Raman spectroscopy on a moderate scale. Here, a new methodology is described that can be used to track changes in crystalline developments during complex Li insertion reactions via the observation of structural color. To be specific, the changes in atomic crystalline and nanostructure are shown during Li insertion in a complex TiO2 polymorph. Structural color corresponds to the refractive indices of materials originating from their atomic bonding nature and precise wave interferences in accordance with their nanostructure. Therefore, this new analysis simultaneously reveals changes in the nanostructure as well as changes in the atomic bonding nature of materials.

Sponge-Like Li4Ti5O12 Constructed on Graphene for High Li Electroactivities.

A sponge-like Li(4)Ti(5)O(12)/graphene composite was prepared via sequential hydrothermal process and solid-state heat treatment process for the application to high-power lithium ion batteries. The as-prepared electrode showed outstanding Li electroactivities with a rapid and reversible Li insertion/ extraction of up to 10 C-rate (1.75 A/g). It delivered a discharge capacity of 174 mAh/g at 0.5 C, near the theoretical capacity of Li(4)Ti(5)O(12), with good rate capability and cyclic stability. First-principles calculations revealed the intimate interaction of the Li(4)Ti(5)O(12) and graphene, which implies that graphene functions as an 'electron tunnel.' Electrochemical impedance spectroscopy also proved that the graphene-hybridization and the unique structure of the Li(4)Ti(5)O(12) material significantly reduce the resistive behavior of electrodes. The 3D structured Li(4)Ti(5)O(12)/graphene hybrid reported herein could be a promising candidate for a safe, low-cost, high-power anode for lithium ion batteries, and our seeding-growth-sintering method for decorating graphene with active material will offer an effective upgrade on highly insulating Li(4)Ti(5)O(12) materials.

Insights into the Li Diffusion Dynamics and Nanostructuring of H2Ti12O25 To Enhance Its Li Storage Performance.

Dodecatitanate H2Ti12O25 crystal has a condensed layered structure and exhibits noteworthy Li storage performance that makes it an anode material with great potential for use in Li-ion batteries. However, an unknown Li diffusion mechanism and a sluggish level of Li dynamics through elongated diffusion paths inside this crystal has impeded any forward development in resolving its limited rate capability and cyclic stability. In this study, we investigated the Li diffusion dynamics inside the H2Ti12O25 crystal that play an essential role in Li storage performance. A study of density functional theory combined with experimental evaluation confirmed a strong dependence of Li storage performance on its diffusion. In addition, a nanostructured H2Ti12O25 containing a bundle of nanorods is developed via the introduction of a kinetic gap during the structural transformation, which conferred a significantly shortened diffusion time/length for Li in H2Ti12O25. The nanostructured H2Ti12O25 has high specific capacity (∼230 mAh g(-1)) and exhibits enhanced cyclic stability and rate capability compared with conventional bulky H2Ti12O25. The H2Ti12O25 proposed in this study has high potential for use as an anode material with excellent safety and stability.

Interfacial Adsorption and Redox Coupling of Li4Ti5O12 with Nanographene for High-Rate Lithium Storage.

Despite the many efforts to solve the problem associated with lithium storage at high rates, it is rarely achieved up until now. The design with experimental proof is reported here for the high rate of lithium storage via a core-shell structure composite comprised of a Li4Ti5O12 (LTO) core and a nanographene (NG) shell. The LTO-NG core-shell was synthesized via a first-principles understanding of the adsorption properties between LTO and NG. Interfacial reactions are considered between the two materials by a redox coupling effect. The large interfacial area between the LTO core and the NG shell resulted in a high electron-conducting path. It allowed rapid kinetics to be achieved for lithium storage and also resulted in a stable contact between LTO and NG, affording cyclic performance stability.