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This paper selected Sansha Bay which was a typical aquacultural bay in Fujian Province as the research area to investigate the current status of aquaculture, and calculated the amount and values of carbon sequestration contributed by mariculture from Sansha Bay. The results showed that the total aquaculture output of Sansha Bay in 2022 was 664 700 t, including 266 700 t of shellfish and algae. The dominant economic species included large yellow croaker, abalone, kelp, Gracilaria and oyster. The carbon ratio of these main cultured organisms varied spatially and temporally, ranging from 23.67% to 43.89% in tissues and 11.12% to 15.05% in shells. The carbon ratio of kelp decreased with the growth cycle, while the carbon ratio of shells showed no significant difference. In 2022, the mariculture of oysters, kelp, Gracilaria and other filter-feeding shellfish in Sansha Bay could remove carbon about 29 100 t from seawater, equivalent to reducing 106 700 t of CO2. It also created an economic value of 1.62 million yuan, with considerable carbon sequestration capacity and economic benefits. However, abalone, large yellow crock, sea cucumber and other bait-based culture organisms introduced about 925 500 t of extraneous carbon sources in the process of mariculture. Irrational input of bait and culture structure were important factors leading to the weak carbon sequestration ability of bait-based culture. This paper focused on the fishery carbon sink accounting of the typical aquaculture bay, and discussed the carbon sequestration capacity of locally bait-based aquaculture species. It would provide scientific basis for the aquaculture planning and the green upgrading and transformation of the aquaculture industry in this area.

Ocean Negative Carbon Emission (ONCE) involves utilizing natural marine chemistry and biology, along with mariculture, to achieve carbon sink goals. Growing awareness of the interplay between aquaculture and the coastal carbonate system has drawn researchers’ attention amid ring CO2 concentrations and the negative impacts of aquaculture on the environment. In this study, twelve sites representing different maricultural types were selected, including macroalgae, shellfish, fish, and non-farming areas. The environmental factors, dissolved inorganic carbon (DIC), total alkalinity (TA), and pCO2, were measured monthly during kelp farming periods. Nitrate is a major component of total nitrogen, and the NO3-N concentration in the macroalgal culture zone was lower than others, indicating effective nitrogen removal by macroalgae aquaculture. TA and DIC in non-farmed areas demonstrated larger variation ranges than in farming areas, probably due to the effects of precipitation on salinity. Aquaculture activities effectively maintained TA and DIC, with macroalgae cultivation playing an important role in TA stability, potentially resisting acidification. The pCO2sea-air of macroalgae culture areas in spring was slightly negative, suggesting carbon sink potential. However, further research is needed to assess the full extent of this “fourth type” of blue carbon, including accurate carbon footprint calculation and the contributions of particulate organic carbon and recalcitrant dissolved organic carbon. This study provided insight into the comprehensive contribution of different aquaculture types to the fishery environment and carbonate system, which can help guide aquaculture management and facilitate the carbon-neutral transition of aquaculture.

Abstract The flashover threshold (Vflsh) of polymer insulations such as epoxy (EP) in HVDC systems can be augmented by modifying their surface with an appropriate treatment technology. For such purpose, several surface treatment methods such as ion beam, sandpaper and a combination of the two is introduced. Firstly, insulation samples with pure epoxy (EPpure), different ion beam treatment periods (EPion;10, 15, 20 min) and different roughness (EPsand; R1 = 4.23 μm, R2 = 6.34 μm, R3 = 9.21 μm) are prepared on the laboratory scale. Afterward, based on several characterisations, such as surface conductivity, mean surface roughness and potential distribution of these insulations, multi‐modified insulation (EPmulti = EPion‐20 + EPsand‐R3) is prepared. In the end, the Vflsh of each insulation group is measured and compared to examine the effectiveness of the proposed modifications. It is obtained that the Vflsh of the modified insulations augmented dramatically irrespective of the treatment method. The Vflsh of the insulation group EPmulti augmented by 52.66 % which is the highest improvement among all insulation groups. In short, the proposed surface modifications are effective and could be used as references to enhance the insulation strength of polymer dielectrics in HVDC systems.

Abstract The flashover strength of epoxy (EP) insulations in the High voltage direct current applications of future energy grids can be improved by tailoring their surface condition. This work aims to improve the DC surface flashover characteristics of EP after being treated with sandpaper of different gradings. Samples with virgin EP and homogenously modified EP considering varying surface roughness (Ra = 0.54, 3.16, 5.24, and 8.35 μm) are prepared. Different experimental characterisations, such as water contact angle, surface intrinsic conductivity, surface voltages, flashover strength, and trap distributions are conducted and evaluated to analyse the difference between virgin and treated EP. Moreover, based on the obtained experimental results of homogenously treated EP and theoretical analysis, the concept of surface functionally graded materials (SFGMs) is put forward. The flashover voltages of homogenously treated EP are augmented significantly compared to virgin EP regardless of the voltage polarity and enhanced by enhancing the surface roughness. The sample TModel‐C with SFGM design shows a 45.02% and 43.75% improvement in the negative and positive flashover voltages than that of the virgin EP. In the end, COMSOL simulations are conducted to justify the experimental findings and to analyse the difference between virgin and modified samples in terms of electric field distribution.

Nanocomposites are promising dielectric candidates due to their nano-modification effect. Here authors report homogeneous nano-sieves of different pore sizes and incorporate them uniformly into P(VDF-HFP)-based films with extremely low dopings.

Abstract The 2050 carbon‐neutral vision spawns a novel energy structure revolution, and the construction of the future energy structure is based on equipment innovation. Insulating material, as the core of electrical power equipment and electrified transportation asset, faces unprecedented challenges and opportunities. The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed. The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated. Insulating materials, including intelligent insulating material, high thermal conductivity insulating material, high energy storage density insulating material, extreme environment resistant insulating material, and environmental‐friendly insulating material, are categorised with their scientific issues, opportunities and challenges under the goal of carbon neutrality being discussed. In the context of carbon neutrality, not only improves the understanding of the insulation problems from a macro level, that is, electrical power equipment and electrified transportation asset, but also offers opportunities, remaining issues and challenges from the insulating material level. It is hoped that this paper envisions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules. The authors also hope that this paper can be helpful in future development and research of novel insulating materials, which promote the realisation of the carbon‐neutral vision.

ObjectiveTo retrospectively analyze the feasibility and efficacy of posterior hemivertebra resection without internal fixation in the treatment of congenital scoliosis in very young children.MethodsSixteen cases of very young children with congenital scoliosis treated at our hospital from April 2000 to July 2019 were collected, including 8 cases of each sex, all of whom had type I/III congenital scoliosis and were operated on at a median (interquartile range) of 9.00 (7.75) months (range, 0.5–48 months) of age. All cases underwent posterior hemivertebra resection without internal fixation and wore orthopedic braces or plaster undershirts for more than six months after surgery, with a mean follow-up of 94.31 ± 65.63 months (range, 36–222 months).ResultsCoronal plane: the preoperative Cobb angle for the segmental curve was 39.50 ± 9.70° compared to postoperative (19.19 ± 8.56°) and last follow-up (14.94 ± 12.11°) (both P 0.05). There was a tendency for the thoracolumbar kyphosis to worsen and the lumbosacral kyphosis to improve during the follow-up period.ConclusionPosterior hemivertebra resection without internal fixation is a feasible treatment for type I/III congenital scoliosis in very young children, but the correction of the sagittal deformity of the thoracolumbar spine is not satisfactory, and postoperative external fixation may require further improvement.

Exploring the responses of microbial communities and their functions to marine frontal systems are the foci of marine ecologists. However, most of the existing studies have focused on only microbial communities or their functions. The relationships between microbial communities and their functions across coastal fronts therefore remain unclear. Here we studied a coastal front in the Taiwan Strait during late spring and examined the bacterial community structure, extracellular enzymatic activity (EEA), and their linkages. The results showed that the coastal front strongly delineated zones of bacterial community composition and diversity and functioned as a transitional zone rather than a hotspot between the coastal water and offshore water. Co-occurrence network analysis indicated that the interaction of bacterial communities was much weaker in the frontal zone than in the water masses on both sides. The suggestion was that the highly fluctuating environment in the frontal zone reduced the complexity and stability of the bacterial co-occurrence network. The activities of β-glucosidase (BGA) and leucine aminopeptidase (LAPA) were as high in the frontal zone as in the coastal water and much higher than those in offshore waters. We therefore suggest that, despite obvious shifts in the bacterial community structure in the frontal zone, the bacterial community was able to maintain its ability to hydrolyze organic substrates via functional redundancy. The composition of key microbial assemblies differed among the three water masses, and the relative abundance of module 2 in the frontal zone was positively correlated with BGA and LAPA. The indication was that changing the bacterial assemblage was the mechanism that made it possible for the bacterial community to maintain EEA in the frontal zone. Our results help to improve understanding on how bacterial community-function linkages vary in marine frontal systems.

Latin Hypercube Design (LHD) is widely used in computer simulation to solve large-scale, complex, nonlinear problems. The high-dimensional LHD (HLHD) problem is one of the crucial issues and has been a large concern in the long run. This paper proposes an improved Hybrid Particle Swarm Optimization (IHPSO) algorithm to find the near-optimal HLHD by increasing the particle evolution speed and strengthening the local search. In the proposed algorithm, firstly, the diversity of the population is ensured through comprehensive learning. Secondly, the Minimum Point Distance (MPD) method is adopted to solve the oscillation problem of the PSO algorithm. Thirdly, the Ranked Ordered Value (ROV) rule is used to realize the discretization of the PSO algorithm. Finally, local and global searches are executed to find the near-optimal HLHD. The comparisons show the superiority of the proposed method compared with the existing algorithms in obtaining the near-optimal HLHD.

Abstract In this work, the boron nitride (BN) nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid. Microstructures and chemical compositions of the nanosized BN are determined. The stability, viscosity, and thermal conductivity of the BN nanofluid, were obtained. And the dissipation factor, electrical conductivity, and relative permittivity of the BN nanofluid, were measured. The ion mobilities and migrating times of the nanofluid were measured under different volumetric fractions of BN nanosheets and temperatures. Results show that the electrical conductivity and dissipation factor of the nanofluid decreased by 54% and 48% with the addition of only 0.1% of BN nanosheets under 110°C. Both the half‐reduced carrier mobility of the nanofluid and the declined ion concentration by blocking of BN nanosheet contributed to the exponentially reduced electrical conductivity and enhanced dielectric performances of the BN nanofluid. The suppression coefficient k is proposed to quantitatively describe the hinder effect of ion migration in nanofluids by 2D BN nanosheet. Results provide a strategy to design and develop advanced nanofluids with low‐dielectric loss by aids of surface adsorption of ion and steric hindrance of 2D nanosheets.

The clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated protein (Cas) system has been widely used for genome editing. In this system, the cytosine base editor (CBE) and adenine base editor (ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine (C) or adenine (A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE (sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal (NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS (F4NLSr2) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE (sCBE) and F4NLSr2 involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.

Base editing, as an expanded clustered regularly interspaced short palindromic repeats (CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9 ortholog from Staphylococcus aureus (SaCas9), is important in genome editing because it can edit sites with HHHAAT protospacer adjacent motif (PAM) that the canonical Streptococcus pyogenes Cas9 (SpCas9) or its variants (e.g. xCas9, Cas9-NG) cannot. However, several technical parameters of SaKKH involved base editors have not been well defined and this uncertainty limits their application. We developed an effective multiplex cytosine base editor (SaKKHn-pBE) and showed that it recognized NNARRT, NNCRRT, NNGRGT, and NNTRGT PAMs. Based on 27 targets tested, we defined technical parameters of SaKKHn-pBE including the editing window, the preferred sequence context, and the mutation type. The editing efficiency was further improved by modification of the SaKKH sgRNA. These advances can be applied in future research and molecular breeding in rice and other plants.

It is well-known that the high-performance polymeric dielectric films used for high-voltage DC capacitors should have outstanding capabilities in terms of electrical and mechanical properties in order to face harsh operating conditions. Many factors limit the ability of these thin films to face different and growing stresses according to modern electrical requirements. Microstructure properties, additives, impurities, defects formed during manufacturing as well as applied stress types significantly affect the performance of dielectric films and their operational lifetime. This paper presents a comprehensive review of the factors which affect the ageing, degradation and breakdown of metallised polypropylene (PP) capacitors films. The effects of microstructure, surface morphological properties, mechanical properties and defects on the reliability of biaxially oriented polypropylene films (BOPP) are studied. In addition, the phenomena affecting dielectric performance and ageing mechanisms which are induced by electrical, thermal and electrothermal stresses are discussed.

This article adds more information to the problem of natural ester use as an electroinsulating fluid in cellulose paper-oil systems, e.g., for use in power transformers. An accelerated thermal aging (120, 140 and 160 °C) of samples consisting of cellulose paper (transformerboard), a treated natural ester (filtered, basic Al2O3, 0.53% DBPC), a copper plate and moisture was studied. Research was especially focused on the impact of moisture on the aging of the above system. Samples with three different oil moisture levels (80, 143 and 305 ppm water content) were subjected to thermal aging to display the change in a selection of properties (tanδ, acid number, water content). For a study of the polarization effects, broadband dielectric spectroscopy (BDS) was performed to observe the complex permittivity and conductivity dependencies on the temperature and frequency (±30 °C, 0.01-107 Hz). Havriliak-Negami (H-N) diagrams were used to further understand the results. The degradation products during thermal aging were recognized by Fourier transform infrared (FT-IR) spectroscopy. Hydrolysis and hydrogenation occurred in the insulating system with a natural ester aged by elevated temperatures, which is in contrast to CO2 formation in the case of electric aging. The results showed an increase in the acid number, dissipation factor, and number of hydrolysis and hydrogenation products. Furthermore, changes in polarization were observed as a consequence of the thermal aging of paper-natural ester insulation system with the presence of copper and moisture.

Antibiotics and nanoplastics are two prevalent pollutants in oceans, posing a great threat to marine ecosystems. As antibiotics and nanoplastics are highly bioconcentrated in lower trophic levels, evaluating their impacts on marine organisms via dietary exposure route is of great importance. In this study, the individual and joint effects of dietborne sulfamethazine (SMZ) and nanoplastic fragments (polystyrene, PS) in marine medaka (Oryzias melastigma) were investigated. After 30 days of dietary exposure, 4.62 mg/g SMZ decreased the Chao1 index (60.86% for females and 26.85% for males) and the Shannon index (68.95% for females and 65.05% for males) and significantly altered the structure of gut microbial communities in both sexes. The female fish exposed to 4.62 mg/g SMZ exhibited higher intestinal sod (43.5%), cat (38.5%) and gpx (39.6%) transcripts, indicating oxidative stress in the gut. PS alone at 3.45 mg/g slightly altered the composition of the gut microbiota. Interestingly, the mixture of SMZ and PS caused more modest effects on the gut microbiota and intestinal antioxidant physiology than the SMZ alone, suggesting that the presence of PS might alleviate the intestinal toxicity of SMZ in a scenario of dietary co-exposure. This study helps better understand the risk of antibiotics and nanoplastics to marine ecosystems.

Through photosynthesis, phytoplankton initiate material cycling and the flow of energy through marine ecosystems. The structure of marine ecosystems is sensitive to the size of primary producers, and size-specific photosynthesis-irradiance (P-I) parameters are required for modeling the size-specific primary production. We defined a phytoplankton type to be a group of phytoplankton communities with similar compositions and hypothesized that a function of phytoplankton types might be used to quantify systematic differences of P-I parameters between size classes (structural effects) and variations of the magnitudes of those parameters if the overlap between habitats was small (environmental effects). To test this hypothesis, we conducted a study to measure the size-specific P-I parameters of two size classes (2 μm) and pigment-based phytoplankton community structure in a marginal sea, the Taiwan Strait. Three phytoplankton types were classified, and type-based and size-specific P-I parameters were derived. The results demonstrated the potential of a type-based model to estimate P-I parameters for two phytoplankton size classes as well as different habitats.

High-spin states in 84Rb are studied by using the 70Zn(18O, p3n)84Rb reaction at a beam energy of 75 MeV. Three high-lying negative-parity bands are established, whose level spacings are very regular, i.e., there is no signature splitting. The dipole character of the transitions of these three bands is assigned by the γ-γ directional correlations of oriented states (DCO) intensity ratios and the multipolarity M1 is suggested by analogy with multiparticle excitations in neighboring nuclei. Strong M1 and weak or no E2 transitions are observed. All these characteristic features show they are magnetic rotational bands.

Nano- and pico-eukaryotes play important roles in the diversity and functions of marine ecosystems. Warm, saline, and nutrient-depleted water that originates in the Kuroshio Current seasonally intrudes into the northern South China Sea (NSCS) from autumn to spring. To clarify the mechanisms in shaping the community structure of nano- and pico-eukaryotes as well as impacts of the Kuroshio intrusion on the NSCS ecosystem, genomic DNA and RNA were co-extracted from samples collected at two depths from nine stations, and then the V9 region of 18S rDNA and rRNA was sequenced with high-throughput sequencing. Our results showed that Dinophyceae was the most diverse and abundant nanoeukaryotic group during the study period revealed by both DNA and RNA surveys. In contrast, the relative read abundance of MAST, Pelagophyceae, and Dinophyceae in the size fraction of picoeukaryotes might be largely underestimated by the DNA survey. The RNA survey was the more reliable method to investigate the eukaryotic community structure. Environmental filtering played an important role in shaping the community structure, and the sampling depth became the governing factor of the beta diversity under the environmental setting of stratification during the study period. The spatial variations in the diversity of nanoeukaryotes were subject to the dispersal limitation under the size rule. The effects of the Kuroshio intrusion on the nanoeukaryotic community structure might also be explained by the dispersal limitation. Overall, neutral processes are critical in shaping the community structure of nanoeukaryotes. The relative metabolic activities of nanoeukaryotes were relatively stable in accordance with the high similarity of community structure between sampling sites. The responses of the relative metabolic activities of picoeukaryotes to environmental factors displayed two distinct patterns: positive correlations with salinity and nutrients and negative with temperature for Dinophyceae, MAST, and Pelagophyceae, while reversed patterns for Mamiellophyceae and Radiolaria. Our findings improve the understanding of the nano- and pico-eukaryotic communities in the NSCS and the mechanisms of their assembly.

In this paper, we experimentally demonstrate that molecules with maximum absorption wavelength corresponding to the first excitation energy of base liquid molecules are able to significantly improve the electrical performances of natural ester oils. The positive lightning impulse breakdown and acceleration characteristics, ac breakdown characteristics, and streamer structure of the natural ester oils, as well as the electronic properties of the molecules, are presented. The molecules with different absorptions in ultraviolet lights were doped into the natural ester oil. The positive lightning impulse breakdown characteristics of natural ester oil with different doped molecules indicated that the doped molecule with great absorption in the medium wavelength ultraviolet irradiation was able to significantly enhance the positive lightning impulse breakdown and acceleration voltages of natural ester oil by 15% and 60%, respectively. In addition, it also enhanced the ac breakdown voltage by 17%. The base liquid molecules exhibited first excitation energy of 4 eV, which corresponds to the maximum absorption wavelength of such molecules, indicating that the improved electric breakdown strength was a result of the reduced the number of excited molecules and weakened ionization of molecules during the streamer propagation.

High-stability triester insulation oil derived from the trimethylolpropane esters (TME) was synthesized by esterifying saturated fatty acids and trimethylolpropane (TMP). The TME oil shows higher AC breakdown voltage (Vb, 72.6 kV/2.5 mm) than that of FR3 (65 kV/2.5 mm). TME oil is readily biodegradable whose biodegradation is 82.2% after 28 days. Pressurized differential scanning calorimetry (PDSC) was applied to measure oxidation onset temperature (OOT) of TME oil for initial evaluating the oxidation stability. Due to the elimination of the carbon-carbon double bonds and β-H, the OOT of the TME oil without antioxidants is approximately 25°C higher than that of FR3. To evaluate the realistic performance of the TME oil, the effect of transformer materials on the aging behavior was investigated. The effect of transformer materials on the thermal aging of TME oil and mineral oil (MO) is less than that of FR3. Although the moisture content and acid value in TME oil induced by aging are higher than those in MO. These acids and moisture do not cause obvious degradation of breakdown voltage and dielectric loss factor, which may be attributed to the high moisture solubility in it.

Exploring impressively effective dielectric nanofluids for transformers to improve dielectric strength and thermal stability is indispensable. It is crucial to determine the modification mechanism of dispersed nanomaterials in insulating oil for operative applications in power transformers. This paper aspires to authenticate the experimental evidence of the enhancing AC dielectric strength of synthetic ester Midel-7131 using two newly introduced semiconductive nanoparticles, CdS and Co3O4, and uncover the potential reasons for enhanced AC dielectric strength. The AC breakdown voltage (BDV) of synthetic ester and nanofluids was investigated and statistically evaluated. The mean AC breakdown voltage of SE/CdS and SE/Co3O4 was increased by 31.9% and 31.3%, respectively. The augmentation in AC breakdown strength is possibly due to the facilitated charge-scavenging ability owing to the large specific surface area and wide bandgap. Simultaneous thermogravimetric analysis, differential scanning calorimetry, and derivative thermogravimetry analyses (TGA–DSC–DTG) confirmed that the initial decomposition temperature was high and heat dissipation was low, indicating that the nanofluids were thermally stable in both air and nitrogen. Hence, emerging semiconductive CdS and Co3O4-based nanofluids of synthetic ester possess remarkable dielectric strength and thermal stability enhancement for their application in power transformers.

Insulating oil is a pivotal component of power transformers, but it suffers from aging byproducts during service operation. The aging byproducts from the degradation of oil insulation tend to induce insulation failure, which poses a significant threat to the security of the power grid. Therefore, the regeneration of insulating oil is required to prolong the useful life of insulating oil and hence be of economic and ecological interests. Typical in-use oil regeneration routes employ multi-step procedures. In this work, a one-step regeneration method using a PVDF/BaTiO3 composite membrane is proposed. BaTiO3 endows the composite membrane with improved hydrophobicity and an electret state. The regeneration performance of the PVDF/BaTiO3 nanofiber membrane was assessed by considering the acid value, moisture content, dielectric loss factor tan δ, and the AC breakdown voltage of the refreshed oil. The test results showed that the filtration efficiencies toward formic acid and moisture were up to 77.5% and 60.6%, respectively. Moreover, the dielectric loss factor tan δ of the refreshed oil decreased evidently at a power frequency, and the AC breakdown voltage rose from 23.7 kV to 38.9 kV. This suggests that the PVDF/BaTiO3 composite membrane may be employed efficiently, and it minimizes aging byproducts via the one-step filtration.

The CRISPR-Cas9 system enables simple, rapid, and effective genome editing in many species. Nevertheless, the requirement of an NGG protospacer adjacent motif (PAM) for the widely used canonical Streptococcus pyogenes Cas9 (SpCas9) limits the potential target sites. The xCas9, an engineered SpCas9 variant, was developed to broaden the PAM compatibility to NG, GAA, and GAT PAMs in human cells. However, no knockout rice plants were generated for GAA PAM sites, and only one edited target with a GAT PAM was reported. In this study, we used tRNA and enhanced sgRNA (esgRNA) to develop an efficient CRISPR-xCas9 genome editing system able to mutate genes at NG, GAA, GAT, and even GAG PAM sites in rice. We also developed the corresponding xCas9-based cytosine base editor (CBE) that can edit the NG and GA PAM sites. These new editing tools will be useful for future rice research or breeding, and may also be applicable for other related plant species.

Tailoring the secondary surface morphology of electro-spun nanofibers has been highly desired, as such delicate structures equip nanofibers with distinct functions. Here, we report a simple strategy to directly reconstruct the surface of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) nanofibers by water evaporation. The roughness and diameter of the nanofibers depend on the temperature during vacuum drying. Surface changes of the nanofibers from smooth to rough were observed at 55 °C, with a significant drop in nanofiber diameter. We attribute the formation of the secondary surface morphology to the intermolecular forces in the water vapor, including capillary and the compression forces, on the basis of the results from the Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy. The strategy is universally effective for various electro-spun polymer nanofibers, thus opening up avenues toward more detailed and sophisticated structure design and implementation for nanofibers.

Base editors that do not require double-stranded DNA cleavage or homology-directed repair enable higher efficiency and cleaner substitution of targeted single nucleotides in genomic DNA than conventional approaches. However, their broad applications are limited within the editing window of several base pairs from the canonical NGG protospacer adjacent motif (PAM) sequence. In this study, we fused the D10A nickase of several Streptococcus pyogenes Cas9 (SpCas9) variants with Petromyzon marinus cytidine deaminase 1 (PmCDA1) and uracil DNA glycosylase inhibitor (UGI) and developed two new effective PmCDA1-based cytosine base editors (pBEs), SpCas9 nickase (SpCas9n)-pBE and VQR nickase (VQRn)-pBE, which expanded the scope of genome targeting for cytosine-to-thymine (C-to-T) substitutions in rice. Four of six and 12 of 18 target sites selected randomly in SpCas9n-pBE and VQRn-pBE, respectively were base edited with frequencies of 4–90% in T0 plants. The effective deaminase window typically spanned positions 1–7 within the protospacer and the single target C showed the maximum C-to-T frequency at or near position 3, counting the end distal to PAM as position 1. In addition, the modified single guide RNA (sgRNA) improved the base editing efficiencies of VQRn-pBE with 1.3- to 7.6-fold increases compared with the native sgRNA, and targets that could not be mutated using the native sgRNA were edited successfully using the modified sgRNA. These newly developed base editors can be used to realize C-to-T substitutions and may become powerful tools for both basic scientific research and crop breeding in rice.

Nanofluids, formed by adding nanoscale particles to insulating oil, are stable and homogeneous suspensions that present advanced performance of electrical insulation and heat dissipation. This study shows a comprehensive literature review based on the related results of nano-modified insulating oils (both mineral and vegetable insulating oils) to analyse the preparation methods, stability, dielectric spectroscopy, thermal conductivity, breakdown characteristics under AC and DC voltage, the thermal aging performance of nanofluids and oil–paper interaction. Then theoretical models have been introduced to explain the electrical mechanism of nanofluids. In addition, future research is proposed for nanofluids which would be low cost, highly stable and practically applicable to the power transformers.

Picoeukaryotes play an important role in the biogenic element cycle and energy flow in oligotrophic ecosystems. However, their biodiversity and activity are poorly studied in open ocean systems, such as the northwestern Pacific Ocean, which is characterized by a complex hydrological setting. Here, we investigated the diversity and activity of picoeukaryotes in the northwestern Pacific Ocean using high-throughput sequencing targeting the V9 region of 18S rDNA and rRNA. Our results showed that the DNA picoeukaryotic communities were mainly represented by Mamiellophyceae, MAST, MALV-II, Spirotrichea, Prymnesiophyceae, and MALV-I (69.33% of the total DNA reads), and the RNA communities were dominated by Spirotrichea, Mamiellophyceae, MAST, Pelagophyceae, and MALV-II (67.46% of the total RNA reads). The number of operational taxonomic units (OTUs) was significantly affected by temperature and salinity, and was decreased with the increasing nutrient concentration both in the DNA and RNA surveys. Significant differences were observed in the community composition between DNA-based and RNA-based molecular approaches, and these differences were mainly attributed to Mamiellophyceae, Spirotrichea, and Pelagophyceae. The RNA: DNA ratio was used as a proxy for relative metabolic activity of the individual OTUs. We found that the relative metabolic activities of Mamiellophyceae, Spirotrichea, and Pelagophyceae species in the northwestern Pacific Ocean were highly affected by the nutrient concentration, i.e., the NO3 + NO2 and SiO3 concentration. Overall, our study shed light on picoeukaryotic diversity and distribution in the northwestern Pacific Ocean and revealed the correlation between the diversity, relative metabolic activities of marine picoeukaryotes, and the environmental factors.

As a new environmentally friendly liquid dielectric material, vegetable insulating oil has been widely used in oil-filled power equipment. In oil-filled power equipment, ageing, faults of overheating and discharge cause the decomposition of insulating oil and insulating paper, resulting in dissolved gases in oils. The diffusion behavior of dissolved gases in oils is helpful for evaluation of health state of oil-filled power equipment. In this study, the molecular dynamics simulation based on polymer consistent force field (PCFF) is adopted to analyze diffusion processes of dissolved gases in camellia insulating oils. The diffusion coefficients and free volume of dissolved gases including hydrocarbons, carbon oxides and hydrogen are calculated. The diffusion trajectory of dissolved gases in oils are also given. In addition, impacts of gas species and temperature on molecular diffusion coefficients of oils were also studied. Results quantitatively describe the diffusion behavior of gases with different molecular weight in the oils under various temperatures. The research provides theoretic support for further application of vegetable insulating oils in power equipment.

In this paper, the Ir-modified MoS2 monolayer is suggested as a novel gas sensor alternative for detecting the characteristic decomposition products of SF6, including H2S, SO2, and SOF2. The corresponding adsorption properties and sensing behaviors were systematically studied using the density functional theory (DFT) method. The theoretical calculation indicates that Ir modification can enhance the surface activity and improve the conductivity of the intrinsic MoS2. The physical structure formation, the density of states (DOS), deformation charge density (DCD), molecular orbital theory analysis, and work function (WF) were used to reveal the gas adsorption and sensing mechanism. These analyses demonstrated that the Ir-modified MoS2 monolayer used as sensing material displays high sensitivity to the target gases, especially for H2S gas. The gas sensitivity order and the recovery time of the sensing material to decomposition products were reasonably predicted. This contribution indicates the theoretical possibility of developing Ir-modified MoS2 as a gas sensor to detect characteristic decomposition gases of SF6.

The effects of C=C, ester and β-H groups on the ionization potential (IP) and electron affinity (EA) of molecules in natural ester insulation oil were investigated by density functional theory (DFT). The major contribution to the highest occupied molecular orbital (HOMO) comes from the carbon atoms adjacent to C=C. Thus, the IPs of triglycerides decrease as the number of C=C double bonds increases. The C=C in alkanes may also lower the IP. However, the β-H in triglycerides has little effect on the IP, and C=C and β-H have only a small effect on the EAs of the triglycerides because of the major contributions of atoms near the ester group in triglycerides to the lowest unoccupied molecular orbital (LUMO). This study calculated the IPs of 53 kinds of molecules in FR3, which are significantly lower compared with those of molecules in mineral oil (MO) and trimethylolpropane triester without C=C. However, the lightning impulse breakdown voltage (LI Vb) of trimethylolpropane triester is still significantly lower than that of MO at the large gap. Therefore, the transition from slow to fast streamers under low lighting impulse voltage is determined by the ester group rather than by C=C and β-H. The ester group may attract more electrons, impacting itself more compared to alkane in MO and facilitating the transition from slow to fast streamers.

Natural esters, as the renewable resources, offer excellent physiochemical and dielectric properties such as the fire-resistance, high biodegradability and satisfactory dielectric breakdown performance. Thus, natural esters are selected as the insulation and heat dissipation medium for electrical equipment. However, the electrical performance of natural esters with different structures under the long gap and higher electrical stress needs further evaluations. In this paper, streamer propagation of various natural esters under the long gap and higher electrical stress were observed optically. The influence of voltage polarity, liquid types and gap distances on streamer characteristics of natural esters were analyzed. Results show that the maximum propagation velocity of streamer in natural esters is greater than that in the hydrocarbon liquids. Breakdown voltage of natural esters under negative polarity is much higher than that under positive polarity for the same gap distance. Among all the natural esters concerned, the camellia liquid demonstrates slower streamer velocity and slight greater lightning breakdown voltages for the positive and negative polarity. The lower content of unsaturation triacylglycerol molecules in camellia liquid contributes to the inhibition of ionization and streamers propagation. Results would be valuable reference for the design, manufacture and operation of the electrical equipment filled with natural ester.

The surface charge and space charge accumulation in paper used in oil−paper insulation system may distort electric field distribution and lead to the flashover and breakdown of insulation system. In this paper, the effect of gas-phase fluorination on the surface charge and space charge characteristics of oil-impregnated Nomex paper was investigated. Nomex T410 was fluorinated at 25 °C using F2/N2 mixtures with 20% F2 in volume at 0.05 MPa for 15, 30 and 45 min. Fourier Transform Infrared Spectroscopy (FTIR) proved that the molecular chain scission and cleavage occurred during gas-phase fluorination. Furthermore, the surface charge and space charge characteristic of the original and fluorinated oil-impregnated paper were measured using an electrostatic voltmeter and Pulsed Electroacoustic (PEA) equipment respectively. Furthermore, the hole and electron trap distribution of the samples were obtained by Isothermal Surface Potential Decay (ISPD) model. The results showed that both the positive and negative charge decay rates were accelerated by gas-phase fluorination and the hole, electron trap energy and density of the fluorinated samples were reduced by fluorination. It is suggested that the space charge dissipation was also accelerated by fluorination, indicating that gas-phase fluorination is an effective approach to modify the charge dynamics of oil-impregnated Nomex paper.

In this paper, the porous NiO/SnO2 nanofibers were synthesized via the electrospinning method along with the carbonization process. The characterization results show that the pristine SnO2-based nanofibers can form porous structure with different grain size by carbonization. The hydrogen gas-sensing investigations indicate that the NiO/SnO2 sensor exhibits more prominent sensing properties than those of pure SnO2 sensor devices. Such enhanced performance is mainly attributed to the porous nanostructure, which can provide large active adsorption sites for surface reaction. Moreover, the existence of p-n heterojunctions between NiO and SnO2 also plays a key role in enhancing gas-sensing performances. Finally, the H2 sensing mechanism based on the NiO/SnO2 nanocomposite was proposed for developing high-performance gas sensor devices.

The eco-friendly vegetable liquid is increasingly used because of the growing demand for environmentally friendly dielectric liquid. A vegetable liquid/fullerene nanofluid was fabricated via ultrasonic processing with good dispersion of the fullerene nanoparticles. It was observed that a small amount of fullerene (~100 mg/L) can significantly improve the electrical properties of vegetable insulating liquid (dissipation factor decreased by 20.1%, volume resistivity increased by 23.3%, and Alternating Current (AC) dielectric breakdown strength increased by 8.6%). Meanwhile, the trace amount of fullerene is also able to improve the electrical performances (i.e., dissipation factor and electrical resistivity) of the vegetable nanofluid under harsh conditions of long-term thermal aging compared with the blank contrast. The reduced acid values (25%) and dissolved decomposition gases (58.2% for hydrogen) in the aged vegetable nanofluid indicate the inhibition of molecule decomposition of vegetable liquid with fullerene. The improved electrical performances and thermal resistance of the vegetable nanofluid contribute to the electron affinity of fullerene proved by calculation of electron density distribution on the surface. The thermogravimetric analysis of the nanofluid under different atmospheres interprets that the oxygen absorbed inevitably in the fullerene contributes to the performance deterioration of the nanofluids during the initial aging. This work provides a potential method towards eco-friendly dielectric liquid with great electrical performances for harsh environments.

In this work, fluorocarbon film was deposited on silicon (P/100) substrate using polytetrafluoroethylene (PTFE) as target material at elevated sputtering temperature. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed to investigate the surface morphology as well as structural and chemical compositions of the deposited film. The surface energy, as well as the polar and dispersion components, were determined by water contact angle (WCA) measurement. The experimental results indicated that increasing sputtering temperature effectively led to higher deposition rate, surface roughness and WCA of the film. It was found that the elevated temperature contributed to increasing saturated components (e.g., C−F2 and C−F3) and decreasing unsaturated components (e.g., C−C and C−CF), thus enhancing the fluorine-to-carbon (F/C) ratio. The results are expected aid in tailoring the design of fluorocarbon films for physicochemical properties.

Vegetable insulating oil may replace the mineral insulating oil used in large power transformers due to its extraordinary biodegradability and fire resistance. According to component analysis, 1-methylnaphthalene and eicosane are considered the typical molecules in mineral oil. Triolein and tristearin are considered the typical molecules in vegetable oil. The ionization potential (IP) and the variation of highest occupied molecular orbital (HOMO) of typical molecules under an external electric field are calculated using quantum chemistry methods. The calculation results show that the IP of the triolein molecule is comparable to that of the 1-methylnaphthalene molecule. The mechanisms of losing electrons are discussed, based on the analysis of HOMO composition. The insulation characteristics of the triolein and tristearin are more likely to be degraded under an external electric field than those of 1-methylnaphthalene and eicosane. Due to the fact that the number density of low IP molecules groups in vegetable oil is much greater than that in mineral oil, the polarity effect in vegetable oil is more obvious than that in mineral oil. This eventually leads to different streamer characteristics in vegetable oil and mineral oil under positive polarity and negative polarity.

Breakdown strength is an important electrical property of insulating paper. Oil-impregnated paper of various aging states was prepared. Its breakdown voltage was then measured at pulsating direct current (DC) voltage with various ripple factors, and alternating current (AC) and DC voltage for comparison, respectively. The AC breakdown voltage is the smallest, and pulsating DC (r = 1/5) breakdown voltage is the greatest before the paper reaches its end of life. A dielectric model was adopted to investigate the difference in magnitude of breakdown voltage at different voltage waveforms. Meanwhile, it was found that breakdown voltage fluctuated and even increased occasionally during the thermal aging process, and a somewhat opposite changing tendency versus aging time was observed for breakdown voltage at DC voltage and pulsating DC voltage with small ripple factors (r = 1/5 and 1/3), compared with AC voltage. The degree of polymerization (DP) and moisture content of the paper were measured, and the characteristics of the pores and cracks of the paper were obtained to investigate the possible influencing factors of breakdown voltage at different aging states. The results showed that the moisture content, oil absorption ability associated with pores and cracks of paper, and the damage to paper structure all contributed to the variation of the breakdown voltage versus aging time, while the importance of their influence differed as the aging state of paper varied.

The insulating performance of oil is vulnerable to particles especially the conductive particles. This paper investigated the influence of copper particles of micrometer size on the breakdown strength and frequency-dependent properties of vegetable oil. The AC breakdown voltage of contaminated vegetable oil with copper particles of different numbers (ranging from 103 to 106) was measured. The frequency-dependent dielectric properties including volume resistivity, relative permittivity and dissipation factor of the contaminated vegetable oil with copper particles of various volumetric concentrations (0.011%, 0.056% and 0.112%) were measured. Identical experiments were conducted with mineral oil for comparison. Results show that the AC breakdown voltage of vegetable oil decreases with the increase of copper particle concentration. The mineral oil exhibits a similar trend, but the influence of copper particles on the AC breakdown voltage of vegetable oil is less significant than that on mineral oil because of its greater viscosity. The relative permittivity and dissipation factor increase with increasing copper volumetric concentration while the volume resistivity decreases. The influence of copper particles on them is significant at low frequencies and this influence becomes inconspicuous as the frequency increases. Similar results were observed for mineral oil.

Natural ester has been widely studied as an alternative dielectric liquid to mineral oil in recent years. Unsaturated triacylglycerol molecules are the main components of natural ester; therefore, in this paper, we investigate the molecular structure and electronic properties of the triolein molecule, an oleic-type triacylglycerol molecule, as a representative component of natural ester oils. The effects of external electric fields at the electric field intensity related to streamer initiation and propagation on the bond lengths, dipole moment, total energy, infrared spectra, and orbital energy of the triolein molecule are investigated using density functional theory (DFT). In addition, the excitation energies, transition wavelengths, and oscillator strengths of the first eight excited states of the triolein molecule under external electric fields are calculated by time-dependent DFT. The results show that the bond lengths, dipole moments, total energy, and infrared spectra change obviously under external electric fields. With increasing external electric field intensity, the energy of the highest occupied molecular orbital increases, and the gap between that and the energy of the lowest unoccupied molecular orbital decreases, which make the molecule susceptible to excitation. The calculations contribute to an understanding of the causes behind the degradation of the insulation properties of natural ester oils.

Bacterial ring rot of potato is one of the most serious potato plant and tuber diseases. Laminaria japonica extract was investigated for its antimicrobial activity against Clavibater michiganense subsp. sepedonicum (Spieckermann & Kotthoff) Davis et al., the causative agent of bacterial ring rot of potato. The results showed that the optimum extraction conditions of antimicrobial substances from L. japonica were an extraction temperature of 80°C, an extraction time of 12 h, and a solid to liquid ratio of 1∶25. Active compounds of L. japonica were isolated by solvent partition, thin layer chromatography (TLC) and column chromatography. All nineteen fractionations had antimicrobial activities against C. michiganense subsp. sepedonicum, while Fractionation three (Fr.3) had the highest (P

The Polygonum orientale L. extracts were investigated for antibacterial activity against Clavibater michiganense subsp. sepedonicum (Spieckermann & Kotthoff) Davis et al., the causal agent of a serious disease called bacterial ring rot of potato. The results showed that the leaf extracts of P. orientale had significantly (p