The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal−air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal−air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li−O2 cells but include Na−O2, K−O2, and Mg−O2 cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O2 reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li−O2 cells. CONTENTS 3.4.1. Electrolytes 3.4.2. Development of New Solvents for Li−O2 N 3.7. Novel Electrolytes and Electrodes AH 3.7.1. The Possibilities and Development of Active Metal (Li, Na) Protection AH 3.7.2. Solid-State Li−Air and Na−Air Batteries AJ 3.7.3. On the Use of Ionic Liquids and Molten Salts AL 3.7.4. On the Possible Use of Solid Li-Oxide Cathodes and the Connection to Lithiated Transition Metals AN 3.8. Studies with Consideration of Practical Metal−Air Batteries AN 3.8.1. Li Batteries with Lithium Oxygen Compound Cathodes (and Closed Systems) AN 3.8.2. Challenges of Capacity and Kinetics AO 3.8.3. On the Validity of E nergy Density Calculation of Li (Na)−Oxygen Batteries AO 3.8.4. From Oxygen to Air AP 3.8.5. Configuration of Li−Air Cells and the Balance of Plant AQ 4. Future Perspective AR 5. Conclusion AS Author Information AT Corresponding Authors AT Authors AT Author Contributions AT Notes AT Biographies AT Acknowledgments AV Abbreviations Used AV References AV G Figure 28. Representative methods for protecting Li metal in Li−O2 batteries. (A) Gel or solid electrolyte. Reproduced with permission from ref 256.

SummaryZearalenone (ZEA) is a polyketide mycotoxin produced by some species of Gibberella/Fusarium and causes hyperestrogenic syndrome in animals. ZEA occurs naturally in cereals infected by Gibberella zeae in temperate regions and threatens animal health. In this study, we report on a set of genes that participate in the biosynthesis of ZEA in G. zeae . Focusing on the non-reducing polyketide synthase (PKS) genes of the G. zeae genome, we demonstrated that PKS13 is required for ZEA production. Subsequent analyses revealed that a continuous, 50 kb segment of DNA carrying PKS13 consisted of three additional open reading frames that were coexpressed as a cluster during the condition for ZEA biosynthesis. These genes, in addition to PKS13 , were essential for the ZEA biosynthesis. They include another PKS gene ( PKS4 ) encoding a fungal reducing PKS; zearalenone biosynthesis gene 1 ( ZEB1 ), which shows a high similarity to putative isoamyl alcohol oxidase genes; and ZEB2 whose deduced product carries a conserved, basic-region leucine zipper domain. ZEB1 is responsible for the chemical conversion of β β β β -zearalenonol ( β β β β -ZOL) to ZEA in the biosynthetic pathway, and ZEB2 controls transcription of the cluster members. Transcription of these genes was strongly influenced by different culture conditions such as nutrient starvations and ambient pH. Furthermore, the same set of genes regulated by ZEB2 was dramatically repressed in the transgenic G. zeae strain with the deletion of PKS13 or PKS4 but not in the ZEB1 deletion strain, suggesting that ZEA or β β β β -ZOL may be involved in transcriptional activation of the gene cluster required for ZEA biosynthesis in G. zeae . This is the first published report on the molecular characterization of genes required for ZEA biosynthesis.

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Fusarium graminearum is an important fungal pathogen of cereal crops and produces mycotoxins, such as the trichothecenes nivalenol and deoxynivalenol. This species may be subdivided into a series of genetic lineages or phylogenetic species. We identified strains of F. graminearum from the Republic of Korea to lineage, tested their ability to produce nivalenol and deoxynivalenol, and determined the genetic composition and structure of the populations from which they were recovered. Based on amplified fragment length polymorphism (AFLP), PCR genotyping, and chemical analyses of trichothecenes, all 249 isolates from southern provinces belonged to lineage 6, with 241 having the nivalenol genotype and 8 having the deoxynivalenol genotype. In the eastern Korea province, we recovered 84 lineage 6 isolates with the nivalenol genotype and 23 lineage 7 isolates with the deoxynivalenol genotype. Among 333 lineage 6 isolates, 36% of the AFLP bands were polymorphic, and there were 270 multilocus haplotypes. Genetic identity among populations was high (>0.972), and genotype diversity was low (30 to 58%). To test the adaptation of lineage 6 to rice, conidial mixtures of strains from lineages 3, 6, and 7 were inoculated onto rice plants and then recovered from the rice grains produced. Strains representing lineages 6 and 7 were recovered from inoculated spikelets at similar frequencies that were much higher than those for the strain representing lineage 3. Abundant perithecia were produced on rice straw, and 247 single-ascospore isolates were recovered from 247 perithecia. Perithecia representing lineage 6 (87%) were the most common, followed by those representing lineage 7 (13%), with perithecia representing lineage 3 not detected. These results suggest that F. graminearum lineage 6 may have a host preference for rice and that it may be more fit in a rice agroecosystem than are the other lineages present in Korea.

The Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic and zoonotic virus with a fatality rate in humans of over 35%. Although several vaccine candidates have been developed, there is still no clinically available vaccine for MERS-CoV. In this study, we developed two types of MERS-CoV vaccines: a recombinant adenovirus serotype 5 encoding the MERS-CoV spike gene (Ad5/MERS) and spike protein nanoparticles formulated with aluminum (alum) adjuvant. Next, we tested a heterologous prime-boost vaccine strategy, which compared priming with Ad5/MERS and boosting with spike protein nanoparticles and vice versa, with homologous prime-boost vaccination comprising priming and boosting with either spike protein nanoparticles or Ad5/MERS. Although both types of vaccine could induce specific immunoglobulin G against MERS-CoV, neutralizing antibodies against MERS-CoV were induced only by heterologous prime-boost immunization and homologous immunization with spike protein nanoparticles. Interestingly, Th1 cell activation was induced by immunization schedules including Ad5/MERS, but not by those including only spike protein nanoparticles. Heterologous prime-boost vaccination regimens including Ad5/MERS elicited simultaneous Th1 and Th2 responses, but homologous prime-boost regimens did not. Thus, heterologous prime-boost may induce longer-lasting immune responses against MERS-CoV because of an appropriate balance of Th1/Th2 responses. However, both heterologous prime-boost and homologous spike protein nanoparticles vaccinations could provide protection from MERS-CoV challenge in mice. Our results demonstrate that heterologous immunization by priming with Ad5/MERS and boosting with spike protein nanoparticles could be an efficient prophylactic strategy against MERS-CoV infection.

Mycelia of Gibberella zeae (anamorph, Fusarium graminearum), an important pathogen of cereal crops, are yellow to tan with white to carmine red margins. We isolated genes encoding the following two proteins that are required for aurofusarin biosynthesis from G. zeae: a type I polyketide synthase (PKS) and a putative laccase. Screening of insertional mutants of G. zeae, which were generated by using a restriction enzyme-mediated integration procedure, resulted in the isolation of mutant S4B3076, which is a pigment mutant. In a sexual cross of the mutant with a strain with normal pigmentation, the pigment mutation was linked to the inserted vector. The vector insertion site in S4B3076 was a HindIII site 38 bp upstream from an open reading frame (ORF) on contig 1.116 in the F. graminearum genome database. The ORF, designated Gip1 (for Gibberella zeae pigment mutation 1), encodes a putative laccase. A 30-kb region surrounding the insertion site and Gip1 contains 10 additional ORFs, including a putative ORF identified as PKS12 whose product exhibits about 40% amino acid identity to the products of type I fungal PKS genes, which are involved in pigment biosynthesis. Targeted gene deletion and complementation analyses confirmed that both Gip1 and PKS12 are required for aurofusarin production in G. zeae. This information is the first information concerning the biosynthesis of these pigments by G. zeae and could help in studies of their toxicity in domesticated animals.

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Non-aqueous lithium-oxygen batteries cycle by forming lithium peroxide during discharge and oxidizing it during recharge. The significant problem of oxidizing the solid insulating lithium peroxide can greatly be facilitated by incorporating redox mediators that shuttle electron-holes between the porous substrate and lithium peroxide. Redox mediator stability is thus key for energy efficiency, reversibility, and cycle life. However, the gradual deactivation of redox mediators during repeated cycling has not conclusively been explained. Here, we show that organic redox mediators are predominantly decomposed by singlet oxygen that forms during cycling. Their reaction with superoxide, previously assumed to mainly trigger their degradation, peroxide, and dioxygen, is orders of magnitude slower in comparison. The reduced form of the mediator is markedly more reactive towards singlet oxygen than the oxidized form, from which we derive reaction mechanisms supported by density functional theory calculations. Redox mediators must thus be designed for stability against singlet oxygen.