Industrially, the artificial fixation of atmospheric nitrogen to ammonia is carried out using the Haber-Bosch process, but this process requires high temperatures and pressures, and consumes more than 1% of the world's power production. Therefore the search is on for a more environmentally benign process that occurs under milder conditions. Here, we report that a Ru-loaded electride [Ca(24)Al(28)O(64)](4+)(e(-))(4) (Ru/C12A7:e(-)), which has high electron-donating power and chemical stability, works as an efficient catalyst for ammonia synthesis. Highly efficient ammonia synthesis is achieved with a catalytic activity that is an order of magnitude greater than those of other previously reported Ru-loaded catalysts and with almost half the reaction activation energy. Kinetic analysis with infrared spectroscopy reveals that C12A7:e(-) markedly enhances N(2) dissociation on Ru by the back donation of electrons and that the poisoning of ruthenium surfaces by hydrogen adatoms can be suppressed effectively because of the ability of C12A7:e(-) to store hydrogen reversibly.

Novel approaches to efficient ammonia synthesis at an ambient pressure are actively sought out so as to reduce the cost of ammonia production and to allow for compact production facilities. It is accepted that the key is the development of a high-performance catalyst that significantly enhances dissociation of the nitrogen–nitrogen triple bond, which is generally considered a rate-determining step. Here we examine kinetics of nitrogen and hydrogen isotope exchange and hydrogen adsorption/desorption reactions for a recently discovered efficient catalyst for ammonia synthesis—ruthenium-loaded 12CaO·7Al2O3 electride (Ru/C12A7:e−)—and find that the rate controlling step of ammonia synthesis over Ru/C12A7:e− is not dissociation of the nitrogen–nitrogen triple bond but the subsequent formation of N–Hn species. A mechanism of ammonia synthesis involving reversible storage and release of hydrogen atoms on the Ru/C12A7:e− surface is proposed on the basis of observed hydrogen absorption/desorption kinetics.

Many multicellular organisms have remarkable capability to regenerate new organs after wounding. As a first step of organ regeneration, adult somatic cells often dedifferentiate to reacquire cell proliferation potential, but mechanisms underlying this process remain unknown in plants. Here we show that an AP2/ERF transcription factor, WOUND INDUCED DEDIFFERENTIATION 1 (WIND1), is involved in the control of cell dedifferentiation in Arabidopsis. WIND1 is rapidly induced at the wound site, and it promotes cell dedifferentiation and subsequent cell proliferation to form a mass of pluripotent cells termed callus. We further demonstrate that ectopic overexpression of WIND1 is sufficient to establish and maintain the dedifferentiated status of somatic cells without exogenous auxin and cytokinin, two plant hormones that are normally required for cell dedifferentiation. In vivo imaging of a synthetic cytokinin reporter reveals that wounding upregulates the B-type ARABIDOPSIS RESPONSE REGULATOR (ARR)-mediated cytokinin response and that WIND1 acts via the ARR-dependent signaling pathway to promote cell dedifferentiation. This study provides novel molecular insights into how plants control cell dedifferentiation in response to wounding.

Ruthenium-loaded metal hydrides with hydrogen vacancies function as efficient catalysts for ammonia synthesis under low temperature and low pressure conditions.

A new quaternary fluoroarsenide CaFeAsF with the tetragonal ZrCuSiAs-type structure composed of alternate stacking of (FeAs)delta- and (CaF)delta+ layers was synthesized. CaFeAsF is a poor metal and shows the anomaly at approximately 120 K in temperature dependence of electrical conductivity. The electron doping by the partial replacement of the iron with cobalt suppresses the anomaly and induces the bulk superconductivity (optimal Tc = 22 K for CaFe0.9Co0.1AsF), analogous to recently discovered FeAs-based superconductors. The present results suggest that CaFeAsF is a promising candidate as a parent compound for high Tc superconductors.

Germination of lettuce (Lactuca sativa L.) seed is regulated by phytochrome. The requirement for red light is circumvented by the application of gibberellin (GA). We have previously shown that the endogenous content of GA 1 , the main bioactive GA in lettuce seeds, increases after red-light treatment. To clarify which step of GA 1 synthesis is regulated by phytochrome, cDNAs encoding GA 20-oxidases (Ls20ox1 and Ls20ox2, for L. sativa GA 20-oxidase) and 3␤-hydroxylases (Ls3h1 and Ls3h2 for L. sativa GA 3␤-hydroxylase) were isolated from lettuce seeds by reverse-transcription polymerase chain reaction. Functional analysis of recombinant proteins expressed in Escherichia coli confirmed that the Ls20ox and Ls3h encode GA 20-oxidases and 3␤-hydroxylases, respectively. Northern-blot analysis showed that Ls3h1 expression was dramatically induced by red-light treatment within 2 h, and that this effect was canceled by a subsequent far-red-light treatment. Ls3h2 mRNA was not detected in seeds that had been allowed to imbibe under any light conditions. Expression of the two Ls20ox genes was induced by initial imbibition alone in the dark. The level of Ls20ox2 mRNA decreased after the red-light treatment, whereas that of Ls20ox1 was unaffected by light. These results suggest that red light promotes GA 1 synthesis in lettuce seeds by inducing Ls3h1 expression via phytochrome action.

A low-temperature ammonia synthesis process is required for on-site synthesis. Barium-doped calcium amide (Ba-Ca(NH ) ) enhances the efficacy of ammonia synthesis mediated by Ru and Co by 2 orders of magnitude more than that of a conventional Ru catalyst at temperatures below 300 °C. Furthermore, the presented catalysts are superior to the wüstite-based Fe catalyst, which is known as a highly active industrial catalyst at low temperatures and pressures. Nanosized Ru-Ba core-shell structures are self-organized on the Ba-Ca(NH ) support during H pretreatment, and the support material is simultaneously converted into a mesoporous structure with a high surface area (>100 m g ). These self-organized nanostructures account for the high catalytic performance in low-temperature ammonia synthesis.

The use of ammonia as a hydrogen carrier has received much attention due to its high hydrogen content and liquid state under mild conditions, which could lead to fuel cell applications. This study demonstrates facile ammonia decomposition on ruthenium nanoparticles loaded on inorganic electride, C12A7:e À . A high turnover frequency ($12 s À1 at 400 C) and low activation energy (64 kJ mol À1 ) for recombinative N 2 desorption were obtained for Ru/C12A7:e À . N 2 -temperature programmed desorption (N 2 -TPD) and kinetic analyses indicate that the high catalytic performance is due to the low work function of chemically stable C12A7:e À , which enables electron injection to the antibonding orbital of the Ru-N bond formed transiently through the reaction by raising the Fermi level of Ru metal.