Damping Properties of Selective Laser-Melted Medium Manganese Mn-xCu Alloy.

In this work, selective laser melting (SLM) technology was applied to directly realize the in situ synthesis of medium manganese Mn-xCu (x = 30-40 wt.%) alloys based on the blended elemental powders. The effects of heat treatment on the microstructural evolution and damping properties of the SLMed Mn-xCu alloys were investigated. The metastable miscibility gap was studied by thermodynamic modeling and microhardness measurement. The results showed that γ-(Mn, Cu) phase with dendritic arm spacing (DAS) of 0.9-1.2 µm was the main constituent phase in the as-SLMed alloys, which was one to two orders of magnitude finer than those of the as-cast samples. Aging at 400-480°C for the Mn-30%Cu or 430°C for Mn-40%Cu alloys can induce spinodal decomposition, martensitic transformation, and α-phase precipitation, whose direct evidence was provided for the first time by transmission electron microscopy and 3D atom probe tomography in the work. The miscibility gap obtained from thermodynamics calculation was basically consistent with the microhardness results for the SLMed Mn-xCu alloys. Solution and aging (SA) treatment can improve the microstructure, tensile and damping properties of the SLMed Mn-xCu alloys more obviously than aging treatment. A 2.3-2.8 and 4.3-4.5 times increase was produced in damping capacity in the aged SLMed and SLMed+SAed Mn-xCu samples, respectively.

Star polymer soil delivery nanoplatform for applying biological agents in the field to control plant rhizosphere diseases.

As the main cause of destructive plant diseases, pathogenic oomycete in plant rhizosphere brings about enormous losses to agricultural production. Although chemical pesticides are still one of the most important prevention and control methods for phytopathogens, the usage of chemical pesticides was limited by the 3R (resistance, residue, and rampant) problem. In the early stage of our research, analysis and comparison of the metabolome of resistance to Phytophthora nicotianae and common strain suggested that naringenin might be a highly efficient potential biogenic antimicrobial agent to prevent and control soil rhizosphere diseases. Unfortunately, the bioactivity and absorption capacity of active ingredients in the environment made it unsuitable for field application; thus, for efficient field application of naringenin, the 24 nm-sized naringenin-loaded nano-star-shaped polymerized (NSPs) were prepared with good loading efficiency 37.3% for naringenin. The soil mobility test indicated that NSPs could effectively reduce the adsorption of active ingredients and enhance the mobility of active ingredients in soil. The bacteriostatic test proved that these NSPs had better antimicrobial activity than the naringenin used alone and could efficiently induce the expression of plant resistance phenylpropanoid compounds. Finally, pot and field experiments showed improved control efficiency of NSPs 41% loaded with naringenin. Transcriptome analysis found that a large number of energy-related genes were downregulated in NSPs nematodes, suggesting that disturbed energy-related genes might lead to the disturbance of energy synthesis and metabolism. Naringenin-loaded nano-carriers were used to prevent and control plant disease-causing pathogens in the rhizosphere, which is of great significance to improve the prevention and control effect and reduce the environmental load of these anti-pathogenic agents.

Construction of a Delivery Platform for Vaccine Based on Modified Nanotubes: Sustainable Prevention against Plant Viral Disease, Simplified Preparation Method, and Protection of Plasmid.

Control of plant viral diseases through cross-protection conferred by an attenuated vaccine is an important strategy for plant protection. However, the mutated site of an attenuated vaccine may not be stably inherited, while viruses have evolved efficient repair mechanisms for the maintenance of genomic integrity. Here, the wide host range and broad selection of mutation sites in cucumber mosaic virus (CMV) enabled construction of an attenuated vaccine through insertional mutation of the CMV 2b protein. CMV-R2E was stably inherited in tobacco for more than 10 generations and had a high relative control efficacy of CMV. Then, the use of polyetherimide (PEI)-modified functionalized carboxylated single-walled carbon nanotubes (PSWNTs) was investigated for vaccine delivery to address the problems of poor stability, complex procedure on field application, and exacting storage conditions with Agrobacterium inoculation. After co-incubating at a 1:300 ratio for 30 min, the vaccine and PSWNTs combined to form pCMV-R2E@PSWNTs, which resulted in a significant increase in the average height of the nanoparticles from 6.56 to 72.34 nm. The relative control efficacy of pCMV-R2E@PSWNTs to CMV was found to be 90.37%. Furthermore, the protective effect of PSWNTs on plasmids was investigated under various environmental conditions and the potential plant toxicity of pCMV-R2E@PSWNTs was assessed, providing a theoretical basis for field application of the vaccine nano-delivery system. A highly effective, stable viral vaccine for plants was thus developed and combined with nanocarriers to address the problems of field application. This approach has the potential to enable wider use of attenuated vaccines for sustainable prevention against plant viral disease in the field.

Delivery of Methoprene-Tolerant dsRNA to Improve RNAi Efficiency by Modified Liposomes for Pest Control.

The application of RNA interference (RNAi) technology for pest control is environmentally friendly and accurate. However, the efficiency of RNAi is often inconsistent and unreliable, and finding a suitable carrier element is considered critical to success in overcoming biotic and abiotic barriers to reach the target site. The fall armyworm, Spodoptera frugiperda (FAW), which is one of most important global agricultural pests, has recently spread rapidly to other parts of the world. In this study, a method to improve the stability and RNAi efficiency of the dsRNA carrier complex was reported. Methoprene-tolerant gene (Met) was selected as a target, a gene which is critical to the growth and development of FAW. Biomaterials nanoliposomes (LNPs) were modified with polyethylenimine (PEI) to deliver the dsRNA of Met. The synthesized Met3@PEI@LNPs reached a size of 385 nm and were found to load dsRNA effectively. Through stability and protection assays, it was found that LNPs provided reliable protection. In addition, the release curve also demonstrated that LNPs were able to prevent premature release under alkaline condition of the insect midgut but accelerate the release after entering the acidic environment of the target cells. The cell transfection efficiency of the prepared LNPs reached 96.4%. Toxicity tests showed that the use of LNPs could significantly improve the interference efficiency, with 91.7% interference efficiency achieved when the concentration of dsRNA in LNPs was only 25% of that of the control. Successful interference of Met demonstrated it could significantly shorten the larval period and make the larvae pupate earlier, thus achieving the purpose of control. In this study, we have demonstrated the use of nanotechnology to provide a novel RNAi delivery method for pest control.

Multiple Levels of Triggered Factors and the Obligated Requirement of Cell-to-Cell Movement in the Mutation Repair of Cucumber Mosaic Virus with Defects in the tRNA-like Structure.

Some debilitating mutations in RNA viruses are repairable; however, the triggering factors of mutation repair remain largely unknown. In this study, multiple triggering factors of mutation repair are identified based on genetic damage to the TLS in CMV. TLS mutations in different RNAs distinctively impact viral pathogenicity and present different types of mutation repair. RNA2 relative reduction level or RNA3 sequence change resulting from TLS mutation is correlated with a high rate of mutation repair, and the TLS mutation of RNA1 fails to be repaired at the high inoculum dose. However, the TLS mutation of RNA1 can be repaired at a low dose of inoculation, particularly around the dilution end-point or in the mixed inoculation with RNA2 having a pre-termination mutation of the 2b gene, an RNAi suppressor. Taken together, TLS mutations resulting in quality or quantity defects of the viral genome or TLS mutations at low doses around the dilution end-point are likely to be repaired. Different levels of TLS mutation repair necessarily require cell-to-cell movement, therefore implying its obligated effect on the evolution of low-fitness viruses and providing a new insight into Muller's ratchet. This study provides important information on virus evolution and the application of mild viral vaccines.

Field application of nanoliposomes delivered quercetin by inhibiting specific hsp70 gene expression against plant virus disease.

BACKGROUND: The annual economic loss caused by plant viruses exceeds 10 billion dollars due to the lack of ideal control measures. Quercetin is a flavonol compound that exerts a control effect on plant virus diseases, but its poor solubility and stability limit the control efficiency. Fortunately, the development of nanopesticides has led to new ideas. RESULTS: In this study, 117 nm quercetin nanoliposomes with excellent stability were prepared from biomaterials, and few surfactants and stabilizers were added to optimize the formula. Nbhsp70er-1 and Nbhsp70c-A were found to be the target genes of quercetin, through abiotic and biotic stress, and the nanoliposomes improved the inhibitory effect at the gene and protein levels by 33.6 and 42%, respectively. Finally, the results of field experiment showed that the control efficiency was 38% higher than that of the conventional quercetin formulation and higher than those of other antiviral agents. CONCLUSION: This research innovatively reports the combination of biological antiviral agents and nanotechnology to control plant virus diseases, and it significantly improved the control efficiency and reduced the use of traditional chemical pesticides.

Improved colorimetric analysis for subtle changes of powdered anthocyanins extracted from Lycium ruthenicum Murr.

Anthocyanins of Lycium ruthenicum (LR) are valuable, whereas stabilities, especially colour stabilities, constrain development. This study investigates stored temperature effects on the stability of powdered anthocyanin extracts of LR in anaerobic conditions and colour changes in simulated applications. We found that temperature had limited effects on anthocyanin contents but negative effects on colour. Colour differences (ΔE) were amplified in simulated applications, 4 °C had the most changes in ΔE in simulated applications, 37 °C caused shrinkage of the colour range towards the yellow area, and changes in ΔE at pH 7 and 9 were summarized by models. In conclusion, during anaerobic storage of powdered anthocyanins, asynchronous changes occur between anthocyanin contents and colour. High storage temperature attenuates colour intensity, but low storage temperature causes more ΔE in applications. Established models are beneficial for decreasing the visual differences in products, deepening the understanding, and offering a new perspective on colour analysis.

Self-assembled bovine serum albumin nanoparticles as pesticide delivery vectors for controlling trunk-boring pests.

BACKGROUND: Trunk-boring pests (TBPs) are an important type of forest pest, TBPs not only feed on the branches and trunks of trees, but also spread quarantine diseases in forests. However, because the larvae of TBPs live inside the trunk and are well concealed, prevention and control are difficult. The lack of effective control methods leads to the death of many trees in forests. In this study, a novel nanopesticide featuring high bioactivity and slow-release properties was developed to control TBPs. Thiacloprid (THI), which is commonly used to control Coleoptera species, was used as a model pesticide. RESULTS: The oleophobic properties of bovine serum albumin (BSA) were exploited to encapsulate the hydrophobic pesticide THI by self-assembly, and the size of the obtained nanoparticles, THI@BSA·NPs, was approximately 23 nm. The loading efficiency reached 70.4%, and THI@BSA·NPs could be released continuously for over 15 days, with the cumulative release reaching 93.5%. The fluorescein isothiocyanate (FITC)-labeled nanoparticles were evenly distributed in the digestive tract and body surface of a typical TBPs, M. alternatus, and the stomach and contact toxicities increased by 33.7% and 25.9%, respectively, compared with those of free THI. Furthermore, the results showed that the transport efficiency of THI@BSA·NPs was highest at a concentration of 50 µg/mL, and the THI@BSA·NPs content in the trunk, from to lower to higher layers, was 8.8, 8.2, 7.6, and 5.8 µg/g. At the same time, THI@BSA·NPs also exhibited high transport efficiency in dead trees. CONCLUSION: The transport efficiency and toxicity of the active ingredients are the key factors for the control of TBPs. This work provided idea for the application of biological delivery system encapsulated hydrophobic pesticides. The novel self-assembled THI@BSA·NPs have promising potential for sustainable control of TBPs.

Sublethal effects of methylthio-diafenthiuron on the life table parameters and enzymatic properties of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae).

The diamondback moth (DBM), Plutella xylostella (L.), is a major pest affecting cruciferous vegetables, and seriously affects the quality and yield of these vegetables. Diafenthiuron is a traditional thiourea-based insecticide, but it is rarely used to control pests on cruciferous vegetables due to its phytotoxicity on these vegetables under high temperature and light conditions. Thus, there is an ongoing need for more effective pesticides that can be used on cruciferous vegetables, possibly including new formulations of diafenthiuron. A new thiourea insecticide, methylthio-diafenthiuron, is intended to optimize the structure of diafenthiuron not only to preserve its insecticidal bioactivity but also to overcome its phytotoxicity to cruciferous vegetables, aiming to control insect pests on cruciferous vegetables. In this study, we compared the toxicity of methylthio-diafenthiuron to some frequently used insecticides on the third-instar larvae of DBM. The parental pupal duration was significantly longer under the treatment than in the control, but the pupal weight, fecundity, and hatching rate significantly decreased. By studying the changes in three detoxifying enzymes within 72 h after treatment with a sublethal concentration, the activity of CarE and ODM in the treatment group significantly increased at first and then decreased. In addition, methylthio-diafenthiuron clearly inhibited three kinds of ATPases in the DBM and significantly reduced the eclosion rate of the pupae. This research provides valuable information for the assessment and rational application of methylthio-diafenthiuron for the control of pests on cruciferous vegetables.

Improved mastering material for multilevel blue laser disc.

In order to get a small-sized pit, the reaction threshold of a photoresist is enhanced by increasing the prebake temperature and time. With the improved photoresist, a pit size corresponding to or even smaller than the minimum pit on a blue laser disc can be obtained on an industrial DVD product line. The improved photoresist may serve as the master material of future multilevel blue laser discs, which might provide a potential solution for the fabrication of multilevel blue laser discs.