A connection between stress and development in the multicelular prokaryote Streptomyces coelicolor

Morphological changes leading to aerial mycelium formation and sporulation in the mycelial bacterium Streptomyces coelicolor rely on establishing distinct patterns of gene expression in separate regions of the colony. sH was identified previously as one of three paralogous sigma factors associated with stress responses in S. coelicolor. Here, we show that sigH and the upstream gene prsH (encoding a putative antisigma factor of sH) form an operon transcribed from two developmentally regulated promoters, sigHp1 and sigHp2. While sigHp1 activity is confined to the early phase of growth, transcription of sigHp2 is dramatically induced at the time of aerial hyphae formation. Localization of sigHp2 activity using a transcriptional fusion to the green fluorescent protein reporter gene (sigHp2–egfp) showed that sigHp2 transcription is spatially restricted to sporulating aerial hyphae in wild-type S. coelicolor. However, analysis of mutants unable to form aerial hyphae (bld mutants) showed that sigHp2 transcription and sH protein levels are dramatically upregulated in a bldD mutant, and that the sigHp2–egfp fusion was expressed ectopically in the substrate mycelium in the bldD background. Finally, a protein possessing sigHp2 promoter-binding activity was purified to homogeneity from crude mycelial extracts of S. coelicolor and shown to be BldD. The BldD binding site in the sigHp2 promoter was defined by DNase I footprinting. These data show that expression of sH is subject to temporal and spatial regulation during colony development, that this tissue-specific regulation is mediated directly by the developmental transcription factor BldD and suggest that stress and developmental programmes may be intimately connected in Streptomyces morphogenesis

2021 roadmap on lithium sulfur batteries

Batteries that extend performance beyond the intrinsic limits of Li-ion batteries are among the most important developments required to continue the revolution promised by electrochemical devices. Of these next-generation batteries, lithium sulfur (Li–S) chemistry is among the most commercially mature, with cells offering a substantial increase in gravimetric energy density, reduced costs and improved safety prospects. However, there remain outstanding issues to advance the commercial prospects of the technology and benefit from the economies of scale felt by Li-ion cells, including improving both the rate performance and longevity of cells. To address these challenges, the Faraday Institution, the UK's independent institute for electrochemical energy storage science and technology, launched the Lithium Sulfur Technology Accelerator (LiSTAR) programme in October 2019. This Roadmap, authored by researchers and partners of the LiSTAR programme, is intended to highlight the outstanding issues that must be addressed and provide an insight into the pathways towards solving them adopted by the LiSTAR consortium. In compiling this Roadmap we hope to aid the development of the wider Li–S research community, providing a guide for academia, industry, government and funding agencies in this important and rapidly developing research space

Atomic Scale Modelling of Two-Dimensional Molecular Self-Assembly on a Passivated Si Surface

International audienceThe self-assembly of two-dimensional (2D) molecular structures on a solid surface relies on the subtle balance between non covalent intermolecular and molecule-surface forces. The energetics of 2D molecular lattices forming different patterns on a passivated semiconductor surface are here investigated by a combination of atomistic simulation methods. Density-functional theory provides structure and charges of the molecules, while metadynamics with empirical forces provides a best guess for the lowest-energy adsorption sites of single molecules and dimers. Subsequently, molecular dynamics simulations of extended molecular assemblies with empirical forces yield the most favorable lattice structures at finite temperature and pressure.The theoretical results are in good agreement with scanning tunneling microscopy observations of self-assembled molecular monolayers on a B-doped Si(111) surface, thus allowing to rationalize the competition of long-range dispersion forces between the molecules and the surface. Such a result demonstrates the interest of this predictive approach for further progress in supramolecular chemistry on semiconductor surface

Nanorings and rods interconnected by self-assembly mimicking an artificial network of neurons

[EN] Molecular electronics based on structures ordered as neural networks emerges as the next evolutionary milestone in the construction of nanodevices with unprecedented applications. However, the straightforward formation of geometrically defined and interconnected nanostructures is crucial for the production of electronic circuitry nanoequivalents. Here we report on the molecularly fine-tuned self-assembly of tetrakis-Schiff base compounds into nanosized rings interconnected by unusually large nanorods providing a set of connections that mimic a biological network of neurons. The networks are produced through self-assembly resulting from the molecular conformation and noncovalent intermolecular interactions. These features can be easily generated on flat surfaces and in a polymeric matrix by casting from solution under ambient conditions. The structures can be used to guide the position of electron-transporting agents such as carbon nanotubes on a surface or in a polymer matrix to create electrically conducting networks that can find direct use in constructing nanoelectronic circuits.The research leading to these results has received funding from ICIQ, ICREA, the Spanish Ministerio de Economia y Competitividad (MINECO) through project CTQ2011-27385 and the European Community Seventh Framework Program (FP7-PEOPLE-ITN-2008, CONTACT consortium) under grant agreement number 238363. We acknowledge E. C. Escudero-Adan, M. Martinez-Belmonte and E. Martin from the X-ray department of ICIQ for crystallographic analysis, and M. Moncusi, N. Argany, R. Marimon, M. Stefanova and L. Vojkuvka from the Servei de Recursos Cientifics i Tecnics from Universitat Rovira i Virgili (Tarragona, Spain).Escarcega-Bobadilla, MV.; Zelada-Guillen, GA.; Pyrlin, SV.; Wegrzyn, M.; Ramos, MMD.; Giménez Torres, E.; Stewart, A.... (2013). Nanorings and rods interconnected by self-assembly mimicking an artificial network of neurons. Nature Communications. 4:2648-2648. https://doi.org/10.1038/ncomms3648S264826484Champness, N. R. Making the right connections. Nat. Chem. 4, 149–150 (2012).Hopfield, J. J. & Tank, D. W. Computing with neural circuits: A model. Science 233, 625–633 (1986).Andres, P. R. et al. Self-assembly of a two-dimensional superlattice of molecularly linked metal clusters. Science 273, 1690–1693 (1996).Eichen, Y., Braun, E., Sivan, U. & Ben-Yoseph, G. Self-assembly of nanoelectronic components and circuits using biological templates. Acta Polym. 49, 663–670 (1998).Kawakami, T. et al. Possibilities of molecule-based spintronics of DNA wires, sheets, and related materials. Int. J. Quantum Chem. 105, 655–671 (2005).Kashtan, N., Itzkovitz, S., Milo, R. & Alon, U. Topological generalizations of network motifs. Phys. Rev. E 70, 031909 (2004).Grill, L. et al. Nano-architectures by covalent assembly of molecular building blocks. Nat. Nanotech. 2, 687–691 (2007).Lafferentz, L. et al. Controlling on-surface polymerization by hierarchical and substrate-directed growth. Nat. Chem. 4, 215–220 (2012).Alivisatos, A. P. et al. From molecules to materials: current trends and future directions. Adv. Mater. 10, 1297–1336 (1998).Pauling, L. The principles determining the structure of complex ionic crystals. J. Am. Chem. Soc. 51, 1010–1026 (1929).Damasceno, P. F., Engel, M. & Glotzer, S. C. Predictive self-assembly of polyhedra into complex structures. Science 337, 453–457 (2012).De Graaf, J. & Manna, L. A roadmap for the assembly of polyhedral particles. Science 337, 417–418 (2012).Percec, V. et al. Controlling polymer shape through the self-assembly of dendritic side-groups. Nature 391, 161–164 (1998).Stupp, S. I. et al. Supramolecular materials: self-organized nanostructures. Science 276, 384–389 (1997).Mann, S. The chemistry of form. Angew. Chem. Int. Ed. 39, 3392–3406 (2000).Sakakibara, K., Hill, J. P. & Ariga, K. Thin-film-based nanoarchitectures for soft matter: controlled assemblies into two-dimensional worlds. Small 7, 1288–1308 (2011).Huang, Z. et al. Pulsating tubules from noncovalent macrocycles. Science 337, 1521–1526 (2012).Ackermann, D., Jester, S.-S. & Famulok, M. Design strategy for DNA rotaxanes with a mechanically reinforced PX100 axle. Angew. Chem. Int. Ed. 27, 6771–6775 (2012).Marx, J. L. Microtubules: versatile organelles. Science 181, 1236–1237 (1973).Heus, H. A. & Pardi, A. Structural features that give rise to the unusual stability of RNA hairpins containing GNRA loops. Science 253, 191–194 (1991).Braun, E., Eichen, Y., Sivan, U. & Ben-Yoseph, G. DNA-templated assembly and electrode attachment of a conducting silver wire. Nature 391, 775–778 (1998).Zhang, S. Fabrication of novel biomaterials through molecular self-assembly. Nat. Biotechnol. 21, 1171–1178 (2003).Cai, X. et al. Integrated compact optical vortex beam emitters. Science 338, 363–365 (2012).Clark, A. W. & Cooper, J. M. Nanogap ring antennae as plasmonically coupled SERRS substrates. Small 7, 119–125 (2011).Armani, A. M., Kulkarni, R. P., Fraser, S. E., Flagan, R. C. & Vahala, K. J. Label-free, single-molecule detection with optical microcavities. Science 317, 783–787 (2007).Frischmann, P. D., Guieu, S., Tabeshi, R. & MacLachlan, M. J. Columnar organization of head-to-tail self-assembled Pt4 rings. J. Am. Chem. Soc. 132, 7668–7675 (2010).Frischmann, P. D. et al. Capsule formation, carboxylate exchange, and DFT exploration of cadmium cluster metallocavitands: highly dynamic supramolecules. J. Am. Chem. Soc. 132, 3893–3908 (2010).Akine, S., Hotate, S. & Nabeshima, T. A molecular leverage for helicity control and helix Inversion. J. Am. Chem. Soc. 133, 13868–13871 (2011).Salassa, G. et al. Extremely strong self-assembly of a bimetallic salen complex visualized at the single-molecule level. J. Am. Chem. Soc. 134, 7186–7192 (2012).Escárcega-Bobadilla, M. V., Salassa, G., Martínez Belmonte, M., Escudero-Adán, E. C. & Kleij, A. W. Versatile switching in substrate topicity: supramolecular chirality induction in di- and trinuclear host complexes. Chem. Eur. J. 18, 6805–6810 (2012).Frischmann, P. D., Jiang, J., Hui, J. K.-H., Grzybowski, J. J. & MacLachlan, M. J. Reversible—irreversible approach to Schiff base macrocycles. Access to isomeric macrocycles with multiple salphen pockets. Org. Lett. 10, 1255–1258 (2008).Glaser, T. Rational design of single-molecule magnets: a supramolecular approach. Chem. Commun. 47, 116–130 (2011).Lee, E. C. et al. Understanding of assembly phenomena by aromatic−aromatic interactions: benzene dimer and the substituted systems. J. Phys. Chem. A 111, 3446–3457 (2007).Grybowski, B. A., Wilmer, C. E., Kim, J., Browne, K. P. & Bishop, K. J. M. Self-assembly: from crystals to cells. Soft Matter. 5, 1110–1128 (2009).Martínez Belmonte, M. et al. Self-assembly of Zn(salphen) complexes: steric regulation, stability studies and crystallographic analysis revealing an unexpected dimeric 3,3′-t-Bu-substituted Zn(salphen) complex. Dalton Trans. 39, 4541–4550 (2010).Salassa, G., Castilla, A. M. & Kleij, A. W. Cooperative self-assembly of a macrocyclic Schiff base complex. Dalton Trans. 40, 5236–5243 (2011).Hormoz, S. & Brenner, M. P. Design principles for self-assembly with short-range interactions. Proc. Natl Acad. Sci. 108, 5193–5198 (2011).Biemans, H. A. M. et al. Hexakis porphyrinato benzenes. A new class of porphyrin arrays. J. Am. Chem. Soc. 120, 11054–11060 (1998).Lensen, M. C. et al. Aided self-assembly of porphyrin nanoaggregates into ring-shaped architectures. Chem. Eur. J. 10, 831–839 (2004).Martin, A., Buguin, A. & Brochard-Wyart, F. Dewetting nucleation centers at soft interfaces. Langmuir. 17, 6553–6559 (2001).Schenning, A. P. H. J., Benneker, F. B. G., Geurts, H. P. M., Liu, X. Y. & Nolte, R. J. M. Porphyrin wheels. J. Am. Chem. Soc. 118, 8549–8552 (1996).Deegan, R. D. et al. Capillary flow as the cause of ring strains from dried liquid drops. Nature 389, 827–829 (1997).Scriven, L. E. & Sternling, C. V. The Marangoni effects. Nature 187, 186–188 (1960).Cai, Y. & Newby, B. Z. Marangoni flow-induced self-assembly of hexagonal and stripe-like nanoparticle patterns. J. Am. Chem. Soc. 130, 6076–6077 (2008).Whitesides, G. M. & Grzybowski, B. Self-assembly at all scales. Science 295, 2418–2421 (2002).Mann, S. Self-assembly and transformation of hybrid nano-objects and nanostructures under equilibrium and non-equilibrium conditions. Nat. Mater. 8, 781–792 (2009).Gröschnel, A. H. et al. Precise hierarchical self-assembly of multicompartment micelles. Nat. Commun. 3, 710 (2012).Adam, M., Dogic, Z., Keller, S. L. & Fraden, S. Entropically driven microphase transitions in mixtures of colloidal rods and spheres. Nature 393, 349–352 (1998).Ohara, P. C., Heath, J. R. & Gelbart, W. M. Self-assembly of submicrometer rings of particles from solutions of nanoparticles. Angew. Chem. Int. Ed. 36, 1077–1080 (1997).Xu, J., Xia, J. & Lin, Z. Evaporation-induced self-assembly of nanoparticles from a sphere-on-flat geometry. Angew. Chem. Int. Ed. 46, 1860–1863 (2007).Yosef, G. & Rabani, E. Self-assembly of nanoparticles into rings: A lattice-gas model. J. Phys. Chem. B 110, 20965–20972 (2006).Khanal, B. P. & Zubarev, E. R. Rings of nanorods. Angew. Chem. Int. Ed. 46, 2195–2198 (2007).Wang, Z. et al. One-step, self-assembly, alignment, and patterning of organic semiconductor nanowires by controlled evaporation of confined microfluids. Angew. Chem. Int. Ed. 50, 2811–2815 (2011).Hong, S. W. et al. Directed self-assembly of gradient concentric carbon nanotube rings. Adv. Func. Mater. 18, 2114–2122 (2008).Palma, M. et al. Controlled formation of carbon nanotube junctions via linker-induced assembly in aqueous solution. J. Am. Chem. Soc. 135, 8440–8443 (2013).Horcas, I. et al. WSXM: A software for scanning probe microscopy and a tool for nanotechnology. Rev. Sci. Instrum. 78, 013705 (2007).Soler, J. M. et al. The SIESTA method for ab initio order-n materials simulation. J. Phys. Cond. Matter 14, 2745–2779 (2002).Haynes, P. D., Mostof, A. A., Skylaris, C. & Payne, M. C. ONETEP: Linear-scaling density-functional theory with plane-waves. J. Phys. Conf. Ser. 26, 143–148 (2006).Valiev, M. et al. NWCHEM: A comprehensive and scalable open-source solution for large scale molecular simulations. Comp. Phys. Commun. 181, 1477–1489 (2010).Plimpton, S. Fast parallel algorithms for short-range molecular dynamics. J. Comp. Phys. 117, 1–19 (1995)

Hydro-ionothermal synthesis of lanthanide-organic frameworks with 1,4-phenylenebis(methylene)diphosphonate

A synthetic approach combining hydrothermal and ionothermal (eutectic mixture of choline chloride and malonic acid) procedures is proposed that allowed the isolation of the first lanthanide-organic frameworks with residues of 1,4-phenylenebis(methylene)- diphosphonic acid (H4pmd), [Ln(Hpmd)(H2O)] (where Ln3+ ) Ce3+ and Pr3+), exhibiting an unprecedented trinodal topology with 3- and 8-connected nodes. The structural details were unveiled from single-crystal X-ray diffraction and the materials were characterized using standard techniques.FCT - POCI-PPCDT/QUI/58377/2004FEDER - POCIGrant - SFRH/BPD/9309/200

Three-dimensional lanthanide-organic frameworks based on di-, tetra-, and hexameric clusters

Three-dimensional lanthanide-organic frameworks formulated as (CH3)2NH2[Ln(pydc)2] · 1/2H2O [Ln3+ ) Eu3+ (1a) or Er3+ (1b); pydc2- corresponds to the diprotonated residue of 2,5-pyridinedicarboxylic acid (H2pydc)], [Er4(OH)4(pydc)4(H2O)3] ·H2O (2), and [PrIII 2PrIV 1.25O(OH)3(pydc)3] (3) have been isolated from typical solvothermal (1a and 1b in N,N-dimethylformamide - DMF) and hydrothermal (2 and 3) syntheses. Materials were characterized in the solid state using single-crystal X-ray diffraction, thermogravimetric analysis, vibrational spectroscopy (FT-IR and FT-Raman), electron microscopy, and CHN elemental analysis. While synthesis in DMF promotes the formation of centrosymmetric dimeric units, which act as building blocks in the construction of anionic ∞ 3{[Ln(pydc)2]-} frameworks having the channels filled by the charge-balancing (CH3)2NH2 + cations generated in situ by the solvolysis of DMF, the use of water as the solvent medium promotes clustering of the lanthanide centers: structures of 2 and 3 contain instead tetrameric [Er4(μ3-OH)4]8+ and hexameric |Pr6(μ3-O)2(μ3-OH)6| clusters which act as the building blocks of the networks, and are bridged by the H2-xpydcx- residues. It is demonstrated that this modular approach is reflected in the topological nature of the materials inducing 4-, 8-, and 14-connected uninodal networks (the nodes being the centers of gravity of the clusters) with topologies identical to those of diamond (family 1), and framework types bct (for 2) and bcu-x (for 3), respectively. The thermogravimetric studies of compound 3 further reveal a significant weight increase between ambient temperature and 450 °C with this being correlated with the uptake of oxygen from the surrounding environment by the praseodymium oxide inorganic core

2021 roadmap on lithium sulfur batteries

Abstract: Batteries that extend performance beyond the intrinsic limits of Li-ion batteries are among the most important developments required to continue the revolution promised by electrochemical devices. Of these next-generation batteries, lithium sulfur (Li–S) chemistry is among the most commercially mature, with cells offering a substantial increase in gravimetric energy density, reduced costs and improved safety prospects. However, there remain outstanding issues to advance the commercial prospects of the technology and benefit from the economies of scale felt by Li-ion cells, including improving both the rate performance and longevity of cells. To address these challenges, the Faraday Institution, the UK’s independent institute for electrochemical energy storage science and technology, launched the Lithium Sulfur Technology Accelerator (LiSTAR) programme in October 2019. This Roadmap, authored by researchers and partners of the LiSTAR programme, is intended to highlight the outstanding issues that must be addressed and provide an insight into the pathways towards solving them adopted by the LiSTAR consortium. In compiling this Roadmap we hope to aid the development of the wider Li–S research community, providing a guide for academia, industry, government and funding agencies in this important and rapidly developing research space

Micrometre-long covalent organic fibres by photoinitiated chain-growth radical polymerization on an alkali-halide surface

On-surface polymerization is a promising technique to prepare organic functional nanomaterials that are challenging to synthesize in solution, but it is typically used on metal substrates, which play a catalytic role. Previous examples on insulating surfaces have involved intermediate self-assembled structures, which face high barriers to diffusion, or annealing to higher temperatures, which generally causes rapid dewetting and desorption of the monomers. Here we report the photoinitiated radical polymerization, initiated from a two-dimensional gas phase, of a dimaleimide monomer on an insulating KCl surface. Polymer fibres up to 1 μm long are formed through chain-like rather than step-like growth. Interactions between potassium cations and the dimaleimide’s oxygen atoms facilitate the propagation of the polymer fibres along a preferred axis of the substrate over long distances. Density functional theory calculations, non-contact atomic force microscopy imaging and manipulations at room temperature were used to explore the initiation and propagation processes, as well as the structure and stability of the resulting one-dimensional polymer fibres

How reproducible are surface areas calculated from the BET equation?

Porosity and surface area analysis play a prominent role in modern materials science. At the heart of this sits the Brunauer-Emmett-Teller (BET) theory, which has been a remarkably successful contribution to the field of materials science. The BET method was developed in the 1930s for open surfaces but is now the most widely used metric for the estimation of surface areas of micro- and mesoporous materials. Despite its widespread use, the calculation of BET surface areas causes a spread in reported areas, resulting in reproducibility problems in both academia and industry. To prove this, for this analysis, 18 already-measured raw adsorption isotherms were provided to sixty-one labs, who were asked to calculate the corresponding BET areas. This round-robin exercise resulted in a wide range of values. Here, the reproducibility of BET area determination from identical isotherms is demonstrated to be a largely ignored issue, raising critical concerns over the reliability of reported BET areas. To solve this major issue, a new computational approach to accurately and systematically determine the BET area of nanoporous materials is developed. The software, called "BET surface identification" (BETSI), expands on the well-known Rouquerol criteria and makes an unambiguous BET area assignment possible