Lithium–sulfur (Li–S) batteries have attracted remarkable attention due to their high theoretical capacity of 1675 mAh g−1, rich resources, inexpensiveness, and environmental friendliness. However, the practical application of the Li–S battery is hindered by the shuttling of soluble lithium polysulfides (LiPSs) and slow redox reactions. Herein, a 3D nitrogen‐doped graphene/titanium nitride nanowires (3DNG/TiN) composite is reported as a freestanding electrode for Li–S batteries. The highly porous conductive graphene network provides efficient pathways for both electrons and ions. TiN nanowires attached on the graphene sheets have a strong chemical anchor effect on the polysulfides, which is proved by the superior performance and by density functional theory calculations. As a result, the 3DNG/TiN cathode exhibits an initial capacity of 1510 mAh g−1 and the capacity remains at 1267 mAh g−1 after 100 cycles at 0.5 C. Even at 5 C, a capacity of 676 mAh g−1 is reached. With a high sulfur loading of 9.6 mg cm−2, the 3DNG cathode achieves an ultrahigh areal capacity of 12.0 mAh cm−2 at a high current density of 8.03 mA cm−2. This proposed unique structure gives a bright prospect in that high energy density and high power density can be achieved simultaneously for Li–S batteries.
Many insect species use multi-component sex pheromones to discriminate among potential mating partners [1-5]. In moths, pheromone blends tend to be dominated by one or two major components, but behavioral responses are frequently optimized by the inclusion of less abundant minor components [6]. An increasing number of studies have shown that female insects use these chemicals to convey their mating availability to males, who can assess the maturity of females and thus decide when to mate [7, 8]. However, little is known about the biological mechanisms that enable males to assess female reproductive status. In this study, we found that females of Helicoverpa armigera avoid nonoptimal mating by inhibiting males with pheromone antagonist cis-11-Hexadecenol (Z11-16:OH). We also show that this antagonist-mediated optimization of mating time ensures maximum fecundity. To further investigate molecular aspects of this phenomenon, we used the CRISPR/Cas9 system to knock out odorant receptor 16 (OR16), the only pheromone receptor tuned to Z11-16:OH. In mutant males, electrophysiological and behavioral responses to Z11-16:OH were abolished. Inability to detect Z11-16:OH prompted the males to mate with immature females, which resulted in significantly reduced viability of eggs. In conclusion, our study demonstrates that the sensitivity of OR16 to Z11-16:OH regulates optimal mating time and thus ensures maximum fecundity. These results may suggest novel strategies to disrupt pest insect mating.
In order to acquire enough nutrients and energy for further development, larvae need to invest a large portion of their sensory equipments to identify food sources. Yet, the molecular basis of odor-driven behavior in larvae has been poorly investigated. Information on olfactory genes, particularly odorant binding proteins (OBPs) and chemosensory proteins (CSPs) which are involved in the initial steps of olfaction is very scarce. In this study, we have identified 26 OBP and 21 CSP genes from the transcriptomes of Helicoverpa armigera larval antennae and mouthparts. A comparison with the 34 OBP and 18 CSP genes of the adult antenna, revealed four novel OBPs and seven novel CSPs. Similarly, 27 OBPs (six novel OBPs) and 20 CSPs (6 novel CSPs) were identified in the transcriptomes of Helicoverpa assulta larval antennae and mouthparts. Tissue-specific profiles of these soluble proteins in H. armigera showed that 6 OBP and 4 CSP genes are larval tissue-specific, 15 OBPs and 13 CSPs are expressed in both larvae and adult, while the rest are adult- specific. Our data provide useful information for functional studies of genes involved in larval foraging.
Highlights d E. corollae larvae and adults sense EBF at different concentrations d OR3-expressing neurons and OBP15 mediate the attraction of E. corollae to EBF d E. corollae OR3 À/À mutants reduce attraction to EBF in both adults and larvae d OR3 mediates long-range detection in adults and short-range attraction in larvae
Trehalase is an indispensable component of insect hemolymph that plays important role in energy metabolism and stress resistance. In this study, we cloned and expressed the gene encoding soluble trehalase (HaTreh-1) of Helicoverpa armigera (cotton bollworm) and characterized the enzyme. HaTreh-1 had a full-length open reading frame encoding a protein of 571 amino acids. Sequence comparison indicated that HaTreh-1 was similar to some known insect trehalases. Two essential active sites (D321 and E519) and three essential residues (R168, R221, and R286) were conserved in HaTreh-1. The recombinant trehalase was expressed in Escherichia coli and purified by nickel exchange chromatography. Molecular weight of the recombinant protein was about 71 kDa, and the optimum HaTreh-1 enzyme activity is at 55°C with pH 6.0. Enzymatic assays showed a Km value of 72.8 mmol/liter and a Vmax value of 0.608 mmol/(liter·min). Inhibition assays in vitro indicated that castanospermine, a polyhydroxylated alkaloid, was an effective competitive inhibitor of trehalase with a Ki value of 6.7 μmol/liter. The inhibitor action of castanospermine was linked to its modification effect on trehalase structure. The circular dichroism spectrum showed that the percentage of α-helix increased under the presence of castanospermine. Results of our study will aid in developing effective trehalase inhibitors for controlling H. armigera in the future.
There
is an increasing food demand with growing population and
limited land for agriculture. Conventional agriculture with nitrogen
(N) fertilizer applications, however, is a key source of ammonia (NH3) emissions that cause severe haze pollution and impair human
health. Organic and conservation agricultural (OCA) practices are
thereby recommended to address these dual challenges; however, whether
OCA provides cobenefits for both air quality and crop productivity
is controversial. Here, we perform a meta-analysis and machine learning
algorithm with data from China, a global hotspot for agricultural
NH3 emissions, to quantify the effects of OCA on NH3 emissions, crop yields and nitrogen use efficiency (NUE).
We find that the effects of OCA depend on soil and climate conditions,
and the 40–60% substitution of synthetic fertilizers with livestock
manure achieves the maximum cobenefits of enhanced crop production
and reduced NH3 emissions. Model forecasts further suggest
that the appropriate application of livestock manure, straw return,
and no-till could increase grain production up to 59.7 million metric
tons (100% of straw return) and reduce maximum US$2.7 billion (60%
substitution with livestock manure) in damage costs to human health
from NH3 emissions by 2030. Our findings provide data-driven
pathways and options for achieving multiple sustainable development
goals and improving food systems and air quality in China.
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