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Ultra-highly conductive optoelectronic modulated single-molecule nickel bis(dithiolene) junctions with strong molecule-electrode coupling
No full textStrong molecule-electrode coupling originating from orbit hybridization between gold and the delocalized molecular wires in single-molecule junctions facilitates facile transport towards smart molecular devices. In this paper, we report ultra-highly conductive single-molecule circuits based on highly delocalized nickel bis (dithiolene) (NiS4) molecular junctions using scanning tunneling microscope break junction technique. Single- molecule charge transport measurement of both NiS4 reveals they exhibits high conductance of 10- 1.49 G 0 and 10-1.51 G 0 , respectively. Moreover, under intervention of high bias voltage the molecular conductance could be further improved to approximately 10- 1.00 G 0 , the highest value reported to date with similar molecular lengths. Theoretical calculations suggest that the strong hybridization of the it-channels and the gold electrodes in both junctions exists and it further extends from molecule-electrode interfaces to metal electrodes as visualized by the isosurface plots of the transmitting eigenstate, which lead to not only a distinct energy shift of the dominated LUMO peaks toward Fermi level, but also broad peaks in the LUMO resonance in the transmission functions. In addition, the both molecular junctions show remarkable photoconductance of approximately 10- 1.00 G 0 under resonant light excitation, due to possible exciton binding in these junctions. Interestingly, the conductance switching of both molecular junctions under optoelectronic modulation is highly reversible, forming a multi-stimulus responsive molecular switch. This work not only provides a building block for fabri- cating highly conducting molecular wires with strong molecule-electrode coupling, but also lays a foundation for designing optoelectronic modulated functional molecule-scale devices
A method for breeding the new anti-vibrio variety of clam
No full text本发明涉及海产经济贝类遗传育种技术领域，特别是一种毛蚶抗弧菌新品种的育种方法。具体为利用半致死浓度的副溶血弧菌胁迫成体毛蚶，对15％存活的个体进行恢复以8％留种率筛选获得抗弧菌毛蚶种贝，进行室内车间育肥将毛蚶培育至性腺发育成熟，并于诱导产卵前通过灭活的副溶血弧菌诱导毛蚶产生可遗传的免疫因子；而后诱导毛蚶产卵，获得毛蚶F1代抗弧菌品系，再将F1代采用“北育南养”的繁育和养殖技术快速将毛蚶苗种培育至性成熟；此后，每年按照胁迫筛选种贝、增强子代免疫力和“北育南养”的方式连续选育即获得遗传稳定、性状优良的毛蚶抗弧菌新品种。本发明方法可显著提高毛蚶的抗弧菌能力和养殖存活率，提高毛蚶养殖业的良种保存与供应能力
Insights into the hydrogen-fueled bioreduction of vanadium(V) by marine<i> Shewanella</i> sp. FDA-1: Process and mechanism
No full textMicrobial-driven V(V) reduction plays a crucial role in its biogeochemical cycle, yet the mechanisms underlying this bioreduction remain inadequately understood. While the effectiveness of organic compounds as electron donors in facilitating bacterial reduction of V(V) has been established, the role of inorganic electron donors in initiating this process at the level of pure cultured bacteria has not been explored. In this study, we report on a marine Shewanella sp. FDA-1 that utilizes hydrogen (H-2) as an energy source to reduce V(V). In addition, the reduction mechanism was investigated through a combination of genomics, RT-qPCR, heterologous expression of key proteins, extracellular secretion analyses, and electron transfer activity assays. Our results demonstrate that H-2 serves as an effective electron donor, enabling Shewanella sp. FDA-1 to reduce V(V) across various salinities (2-7 %) and pH values (5-9). When exposed to 5 mM V(V), the presence of 1-20 mL of H-2 resulted in V(V) bioreduction rates ranging from 0.039 to 0.11 h(-1) (R-2 > 0.73). Amorphous V(IV) compounds were characterized as reduction products using XRD, XPS, FTIR, and SEM. Mechanistic studies indicate that the glutathione system, cytochromes, and extracellular substances such as riboflavin play important roles in V(V) reduction (p < 0.05). Furthermore, our findings reveal that the addition of H-2 and lactate triggers different response sequences among these three reduction pathways, suggesting distinct reduction mechanisms between organic and inorganic electron donors. These insights enhance our understanding of microbial vanadium transformation and provide valuable guidance for developing novel H2-based remediation technologies for vanadium-contaminated environments
Potentiometric enzymatic aptasensing of paralytic shellfish toxins using graphene-wrapped magnetic nanospheres and an all-solid-state cadmium-selective microelectrode
No full textA highly sensitive potentiometric enzymatic aptasensing system for the detection of paralytic shellfish toxins (PSTs) is developed by integrating graphene-wrapped magnetic nanospheres (Fe3O4@SiO2@rGO) with an allsolid-state ion-selective microelectrode. The multilayered core-shell structure of Fe3O4@SiO2@rGO enhances the efficient adsorption of aptamer molecules tagged with cadmium sulfide (CdS) nanoparticles. These CdSaptamer conjugates, when bound with PST molecules, can be desorbed from the Fe3O4@SiO2@rGO surface into the sample solution and subsequently digested by deoxyribonuclease I (DNase I). This digestion process releases the PST molecules for recirculation, significantly reducing the retention of CdS on the surface of Fe3O4@SiO2@rGO. After magnetic separation and acid dissolution, the released Cd2+ from the magnetic nanospheres are measured using an all-solid-state Cd2+-selective microelectrode, enabling sensitive potentiometric detection of PSTs. Using gonyautoxin 1/4 (GTX 1/4) as a model, the sensing system exhibits a linear concentration range from 5 to 150 pM and a low detection limit of 1.7 pM for GTX 1/4, and has been successfully applied in the analysis of seawater samples
Water exchange frequency affects the fractions of sulfur and heavy metals in mariculture sediments
No full textWater exchange is a key step in mariculture activities. However, the impact of water exchange frequency (WEF) on the environmental behavior of sulfur and heavy metals is not well understood. In this study, the migration and transformation of sulfur and heavy metals in mariculture sediments under different WEFs were investigated. The results indicated that high WEF would be unfavorable to overlying water quality, while increased acid volatile sulfur (AVS) in the sediments (11.13 mu mol/g). High WEF accelerated the release of heavy metals from bottom sediments and their enrichment in the surface layer, leading to an increase in heavy metal content in the surface sediments, with Cd showing particularly significant changes (CV, similar to 20%). Moreover, the WEF also had an obvious effect on the Cd fraction (CV>10%). The increase in acid-soluble Pb inhibited the conversion of AVS to chromium (II)-reducible sulfur (CRS) in the sediments, enhancing the sediment aging process. An appropriate frequency of water exchange (once every 5 days) could increase the abundance and diversity of bacteria and help to shape specific microorganisms. Changes in heavy metals in the surface sediments caused Firmicutes to become the most affected bacterial species by the WEF. The functional flora involved in the sulfur cycle were lesser affected by the WEF (CV, similar to 5%), whereas those involved in the nitrogen cycle were more affected (CV >17%). The findings provide guidance for scientific mariculture
Three-way crossed scallops between <i>Argopecten</i> <i>irradians irradians</i>, <i>A. i. concentricus </i>and <i>A. purpuratus</i> exhibit strong heterosis in growth, survival and temperature tolerance
No full textThe bay scallops, including the northern subspecies Argopecten irradians irradians (NN) and southern subspecies A. i. concentricus (SS), are economically important cultured bivalves in China. Due to their hermaphroditic nature, the currently farmed bay scallops often suffered from significant inbreeding depression characterized by slow growth, high mortality and low-stress tolerance, especially in the hot summers. In this study, to further improve the production performance and stress resistance of bay scallops, we first conducted a two-way intraspecific hybridization between the two subspecies of the bay scallops (NN and SS), and then hybridized the two-way hybrids with the Peruvian scallop, A. purpuratus (PP) and obtained two three-way hybrids, NSP and SNP. During embryonic and larval stages, both two three-way hybrids exhibited higher fertilization rate, hatching rate and metamorphosis rate, larger initial D-larvae size, and faster embryonic development and larvae growth than those of their parental stocks. The two three-way crossed hybrids displayed excellent heterosis in both growth and survival at larval stage. Both egg origin and mating strategy had significant effects on growth at the larval stage, while the survival rate was mainly dictated by mating strategy. At adult grow-out stage, the heteroses in NSP and SNP cohorts were 12.36 and 19.92 in shell height, 40.37 and 53.27 in whole body weight, and 13.73 and 21.13 in survival rate at harvest, respectively. Moreover, temperature stress tolerance was significantly improved in the three-way crossed scallops. The gonads of most three-way crossed hybrids seemed to be morphologically and functionally females, although the fertility of eggs was very low, suggesting that more energy would be allocated for growth and survival. Notably, the genetic diversity was increased in both three-way hybrids. Therefore, the three-way crossed scallops are potentially precious breeding material for selecting new scallop strains and can be potentially widely cultured along both the southern and northern China coasts
Synergistic effects of ocean acidification and sulfamethoxazole on immune function, energy allocation, and oxidative stress in Trochus niloticus
No full textOcean acidification, a major consequence of climate change, poses significant threats to marine organisms, particularly when combined with other environmental stressors such as chemical pollution. This study investigated the physiological responses of Trochus niloticus to a 28-day exposure of ocean acidification and/or sulfamethoxazole, a commonly detected antibiotic in the South China Sea. Exposure to either acidification or sulfamethoxazole individually triggered adaptive responses through immune activation, antioxidant reactions, and metabolic adjustments. However, concurrent exposure resulted in significant adverse effects, including compromised immunity, oxidative damage, and disrupted energy budget. These findings provide new insights into how ocean acidification interacts with antibiotic pollution to synergistically impact marine gastropods, suggesting that multiple stressors may pose greater threats to T. niloticus populations than single stressors alone
Synthesis and antioxidant evaluation of coumarin-functionalised chitosan: A potent, non-toxic free radical scavenging compound
No full textIn the present study, we designed to link the coumarin molecule to chitosan via a triazole group and synthesized chitosan-coumarin derivatives, which were further quaternized in one step in order to further improve their solubility to obtain a second series of chitosan-coumarin ammonium salt derivatives. The structures of these chitosan derivatives were verified by FT-IR and 1 H NMR. They were tested for their antioxidant activities. The experimental results showed that the derivatives had excellent free radical scavenging ability. The introduction of the coumarin moiety significantly improved the antioxidant activity, and the scavenging capacity was much higher than that of the chitosan feedstock in all three antioxidant tests. Overall, the scavenging capacity of chitosan-coumarin ammonium salt derivatives was slightly higher than that of chitosan-coumarin derivatives, with the highest scavenging rates in all three tests. Compound 8B scavenged 98.74 % (0.01 mg/mL) of superoxide anion radicals, compound 8D scavenged 95.5 % (0.3 mg/mL) of DPPH radicals and compound 8A scavenged 92.97 % (0.2 mg/mL) of hydroxyl radicals. Toxicity assays used L929 cells demonstrated that there was no significant toxicity of the derivatives. The results indicated that the chitosan derivatives described herein were safe and non-toxic and have good antioxidant activity
W/O/W Pickering emulsions stabilized by complex modified phycocyanin
No full textBACKGROUND: A water-in-oil-in-water (W/O/W) double emulsion can simultaneously load hydrophilic and hydrophobic sub-stances due to its unique two-membrane, three-phase structure. However, thermodynamic instability greatly limits the appli-cation of double emulsions in food processing. Further development of Pickering emulsions based on proteins, etc., canimprove the stability and loading capacity. It is of great significance to promote their practical application. RESULTS: Herein, we prepared ultrasound pretreatment complex glycation-modified phycocyanin (UMPC) to stabilize a W/O/WPickering emulsion for the codelivery of vitamin B12 (VB12) and vitamin E (VE). First, an inner water phase and oil phase con-taining polyglycerin polyricinoleate were homogenized to prepare a W/O emulsion. Subsequently, the W/O emulsion washomogenized with an outer water phase containing UMPC to obtain a W/O/W Pickering emulsion. A gel-like inner phase emul-sion with excellent storage and thermal stabilities was obtained under the condition that the W/O emulsion volume ratio was80% and the UMPC was stabilized by 10 g kg-1. The double emulsion after loading VB12 and VE showed good encapsulationeffect during the storage period, the encapsulation rate could reach more than 90%, it also showed excellent protection effectunder long-time storage and UV irradiation and the retention rate increased by more than 65%. In addition, the bioavailabilityof VB12 and VE significantly increased during simulated gastrointestinal digestion and reached 46.02% and 52.43%,respectively. CONCLUSION: These results indicate that the UMPC-stabilized W/O/W Pickering emulsion is an effective carrier for the codeliv-ery of hydrophilic and hydrophobic bioactive molecules and also provides a means for useful exploration of an efficient andstable emulsion system stabilized by biological macromolecules
Vertical transfer of microplastics in nearshore water by cultured filter-feeding oysters
No full textMicroplastics (MPs) are widely distributed in the sea, but the vertical transfer of MPs by marine organisms in coastal area is still poorly understood. In this study, we used laser direct infrared (LDIR) spectroscopy to determine the number and characteristics of MPs deposited by cultured oyster Crassostrea gigas and further compared the differences between MPs of natural deposit and biodeposit in field environments. The amounts of MPs found in the biodeposit of cultured oysters were 3.54 times greater than that in the natural deposition. The polymer types of biodeposit MPs also differed from those of natural deposition. It was estimated that a single oyster can deposit 15.88 MPs per day, which is a figure much higher than the initial results, and hotspots of MPs deposition may be formed within the oyster aquaculture area. We used generalized linear mixed model (GLMM) to further infer the sources of MPs in sediments and found that distance to shore, cultured zone and urban center were important predictors of MPs abundance in sediments of aquaculture area. The above results suggest tha