Intercalating Ultrathin MoO_3 Nanobelts into MXene Film with Ultrahigh Volumetric Capacitance and Excellent Deformation for High-Energy-Density Devices

The restacking hindrance of MXene films restricts their development for high volumetric energy density of flexible supercapacitors toward applications in miniature,portable,wearable or implantable electronic devices.A valid solution is construction of rational heterojunction to achieve a synergistic property enhancement.The introduction of spacers such as graphene,CNTs,cellulose and the like demonstrates limited enhancement in rate capability.The combination of currently reported pseudocapacitive materials and MXene tends to express the potential capacitance of pseudocapacitive materials rather than MXene,leading to low volumetric capacitance.Therefore,it is necessary to exploit more ideal candidate materials to couple with MXene for fully expressing both potentials.Herein,for the first time,high electrochemically active materials of ultrathin MoO3 nanobelts are intercalated into MXene films.In the composites,MoO3 nanobelts not only act as pillaring components to prevent restacking of MXene nanosheets for fully expressing the MXene pseudocapacitance in acidic environment but also provide considerable pseudocapacitive contribution.As a result,the optimal M/MoO3 electrode not only achieves a breakthrough in volumetric capacitance(1817 F cm-3 and 545 F g-1),but also maintains good rate capability and excellent flexibility.Moreover,the corresponding symmetric supercapacitor likewise shows a remarkable energy density of 44.6 Wh L-1(13.4 Wh kg-1),rendering the flexible electrode a promising candidate for application in high-energy-density energy storage devices.

Feeding Deterrence of Common Spices against <i>Helicoverpa armigera</i>Larvae

Edible spices with strong smells or heavy tastes may be a promising resource of feeding deterrents. We compared the feeding deterrence of the ethanol extracts of 21 common spices against the larvae of a generalist pest species, Helicoverpa armigera, using a multiple-choice leaf disc bioassay. The results show that Zanthoxylum bungeanum extract (as a reference) always evoked significant feeding deterrence, while Piper nigrum (both black pepper and white pepper), Piper longum, and Angelica dahurica evoked the strongest and equivalent feeding deterrence. The potent feeding deterrent activity of Piper species may be a common characteristic at genus level.

Rules of Pesticide Use for Food Crop Diseases and Pests: A Concise Diagram Based on Correspondence Analysis

In order to ensure food security, the selection of pesticide must take into account the controlling effect and economy in the chemical control of food crop diseases and pests. Although China has registered a large number of pesticides and fungicides on food crops, traditional statistical methods cannot treat the complex relationships between crops, pests and diseases, as well as pesticides. To this end, the correspondence analysis was used to mine the data of pesticides being registered after January 1, 2010 for the prevention and control of pests and diseases on wheat, corn, and rice in China, in order to reveal the general rules of pesticide use for the prevention and control of grain crop pests and diseases and to provide scientifically recommended pesticide regimens.(1) Recommended pesticides for wheat diseases and pests: For underground pest control, phoxim, diazinon or clothianidin is recommended;imidacloprid is recommended for aphid control;avermectin is recommended for mite control;chlorpyrifos is recommended for midge control;the pesticides for rust control could be selected according to the order of epoxiconazole>flutriafol>kresoxim-methyl>cyproconazole≈hexaconazole;tebuconazole is recommended for the prevention and control of smut;difenoconazole is recommended for the simultaneous occurrence of take-all, smut and sheath blight;it is recommended to use carbendazim or thiophanate-methyl for the control of scab;and triazolone or pyraclostrobin is recommended for the control of powdery mildew.(2) Recommended pesticides for corn diseases and pests: For the control of underground pests, fipronil, carbosulfan or chlorpyrifos are recommended;thiamethoxam is recommended for control of planthoppers and corn aphids;Bacillus thuringiensis or phoxim is recommended for control of corn borers;pyraclostrobin is recommended for the control of northern leaf blight;tebuconazole is recommended for the control of head smut;and fludioxonil+metalaxyl-M is recommended for the control of corn stalk rot.(3) Recommended pesticides for rice diseases and pests: It is recommended to use triazophos, avermectin analogs or methoxyfenozide for the control of borers;for rice planthoppers, the pesticides could be selected in order of pymetrozine>imidacloprid>thiamethoxam>thiazide>nitenpyram;avermectin analogs are recommended for the control of rice leaf rollers;tebuconazole is recommended for the control of rice false smut;prochloraz and its manganese salts are recommended for the control of bakanae disease;hymexazol is recommended for the control of wilt disease;thifluzamide or hexaconazole is recommended for the control of sheath blight;and the pesticides for the control of rice blast are in order of tricyclazole>kasugamycin>fenoxanil>isoprothiolane>Bacillus subtilis. In addition, potential applications of correspondence analysis in other fields of plant protection are discussed.

Innate Preferences for Radial Gradient Pattern Cues in the Cotton Bollworm, <i>Helicoverpa armigera</i>

Information is lacking regarding the visual cues used by Helicoverpa armigera moths during nectar feeding. Here, we investigated the preference for radial gradient patterns in H. armigera moths. The results indicated that both sexes shared a preference to plain flower models of blue and cyan. The radial gradient pattern (cyan as nectar guide color and blue as petal color) was more attractive than its component plain colors (cyan or blue), especially in male moths. Number of corolla petals did not influence the attractiveness of the cyan-blue pattern. The addition of a tertiary floral attractant to white-blue or cyan-blue radial gradient patterns could dramatically enhance the attractiveness of visual cues in males rather than females, suggesting that males gave a higher weight in olfactory modality than females gave, while females gave a higher weight in vision modality than males gave. All together, we found an optimal combination of floral cues in H. armigera sexes as follows: A tertiary floral attractant (2 μL dose of phenylacetaldehyde, benzyl acetate, and salicylaldehyde mixed in 26:15:2) added to white-blue radial gradient flower model (3 cm in diameter). To our knowledge, this is the first time that rose curve and radial gradient tools were used to simulate floral pattern in the studies of flower-visiting insects.

Generation of Feedback-induced Chaos in a Semiconductor Ring Laser

A scheme for chaotic signal generation in a semiconductor ring laser (SRL) with optical feedback is presented. Part of the output is returned to the SRL, resulting in chaotic oscillation.

Concentrated hydrogel electrolyte for integrated supercapacitor with high capacitance at subzero temperature

Hydrogel electrolytes with anti-freezing properties are crucial for flexible quasi-solid-state supercapacitors operating at low temperatures.However,the electrolyte freezing and sluggish ion migration caused by the cold temperature inevitably damage the flexibility and electrochemical properties of supercapacitors.Herein,we introduce the concentrated electrolyte into a freezecasted poly(vinyl alcohol)hydrogel film not only reducing the freezing point of the electrolyte(−51.14℃)in gels for ensuring the flexibility,but also improving the ionic conductivity of the hydrogel electrolyte(5.92 mS cm^(−1)at−40℃)at low temperatures.As a proof,an all-in-one supercapacitor,synthesized by the one-step polymerization method,exhibits a good specific capacitance of 278.6 mF cm^(−2)at−40℃(accounting for 93.8%of the capacitance at room temperature),high rate performance(50%retention under the 100-fold increase in current densities),and long cycle life(88.9%retention after 8,000 cycles at−40℃),representing an excellent low-temperature performance.Our results provide a fresh insight into the hydrogel electrolyte design for flexible energy storage devices operating in the wide range of temperature and open up an exciting direction for improving all-in-one supercapacitors.

Identification and genetic characterization of Contracaecum sp.(Nematoda:Anisakidae)from China

Contracaecum species are economically important fish-borne larval nematodes with zoonotic significance.In June 2019,more than 100 piscivorous birds died in their habitats close to the Wild Duck Lake,located in Yanqing,northwest of Beijing,China.Post-mortem examination of Black Night Herons(Nycticorax)revealed the presence of numerous anisakid nematodes in the proventriculus.Recovered nematodes were identified as Contracaecum sp.based on morphological description.Phylogenetic analysis of the mitochondrial(mt)genome and the ITS gene showed that sequences of Contracaecum sp.Beijing isolates were grouped into a new individual cluster.Furthermore,the parasite was successfully isolated from fresh dead birds,feces of piscivorous birds,and fish and prevalence ranged from 8.0%to 81.8%.Consequently,our study demonstrated Contracaecum sp.infections in different sources from China,which might constitute a threat to wildlife,aquaculture,and public health.