Scalable processing of cementitious composites reinforced with carbon nanotubes (CNTs) and carbon nanofibers (CNFs)

Utilizing the unique properties of CNTs and CNFs to enhance the mechanical and fracture properties of cement based materials and develop smart cementitious nanocomposites can be a challenge in terms of developing scalable manufacturing methods. Scaling up the manufacturing size of CNT and CNF reinforced cement based materials and produce multifunctional concrete that exhibits exceptional strength, stiffness and toughness and multifunctionality requires optimization of dispersion procedure. The effectiveness of successfully using CNTs and CNFs in concrete depends on the fiber count, the volume fraction of sand and coarse aggregates. In this work, we present the flexural strength and stiffness, fracture toughness and brittleness of nanomodified pastes and mortars reinforced at amount of 0.08 and 0.1 wt% and an investigation on the optimization of the fiber count proportioning of concrete. The addition of a very low amount, 0.1 wt%, of both CNTs and CNFs, increases approximately 1.5 times the flexural strength and the Young`s modulus of concrete nanocomposites. The nanomodified concrete also exhibits 60% higher energy absorption capability

Dual-function coatings to protect absorbent surfaces from fouling

Fouling of surfaces caused by pollution, contamination, humidity and microorganisms is one of the major sources of the degradation of mineral and composite materials. The inhibition of foulant growth is essential for the prevention of different kinds of damage, ranging from aesthetic, mechanical and chemical, to risks concerning human and environmental health. This study proposes a new approach for the development of a transparent preservative material with water-repellent and biocide attributes through the use of a sol-gel method. It was found that Si–O–Si dense networks can effectively grow into the micro-pores of mineral and cellulose-based materials, promoting self-cleaning properties as well as sufficient protection against bio-fouling

A Novel Labda-7,13E-dien-15-ol-Producing Bifunctional Diterpene Synthase from Selaginella moellendorffii

Vascular plants invariably contain a class II diterpene cyclase (EC 5.5.1.x), as an ent-copalyl diphosphate synthase is required for gibberellin phytohormone biosynthesis. This has provided the basis for evolution of a functionally diverse enzymatic family.[1] These biocatalysts fold their substrate, the general diterpenoid precursor (E,E,E)-geranylgeranyl diphosphate (GGPP), to bring the terminal three carbon-carbon double bonds into proximity with each other, and then carry out bicyclization via a protonation-initiated carbocation cascade reaction. The resulting labda-15-en-8-yl+ diphosphate intermediate is most commonly quenched by deprotonation at an exocyclic methyl, as in the production of labdadienyl/copalyl diphosphate (Scheme 1). Alternatively, the bicyclized labda-15-en-8-yl+ diphosphate intermediate can be captured by water prior to deprotonation, to form hydroxylated compounds such as labda-15-en-8-ol diphosphate.[2] In addition, this intermediate can undergo subsequent rearrangement via 1,2-hydride and/or methyl shifts, starting with the hydrogen substituent on the neighboring endocyclic methine (C9).[3] However, terminating deprotonation at the neighboring endocyclic methylene (C7) has not previously been observed. Here we report that the lycophyte Selaginella moellendorffii contains a bifunctional diterpene synthase, SmCPSKSL1, which catalyzes just such a class II cyclization reaction. In particular, SmCPSKSL1 produces an endocyclic double bond isomer of copalyl diphosphate (CPP), as well as carries out subsequent replacement of the diphosphate by a hydroxyl group to form labda-7,13E-dien-15-ol. Although this is a known plant metabolite,[4] and a small family of bioactive derived natural products is known from a phylogenetically diverse group of plants,[4-5] its biosynthesis has not been previously investigated. Our results demonstrate that this diterpenoid can be generated by a single bifunctional diterpene synthase that directly generates the endocyclic double bond, as well as hydroxyl group

RNA-seq discovery, functional characterization, and comparison of sesquiterpene synthases from Solanum lycopersicum and Solanum habrochaites trichomes

Solanum lycopersicum and Solanum habrochaites (f. typicum) accession PI127826 emit a variety of sesquiterpenes. To identify terpene synthases involved in the production of these volatile sesquiterpenes, we used massive parallel pyrosequencing (RNA-seq) to obtain the transcriptome of the stem trichomes from these plants. This approach resulted initially in the discovery of six sesquiterpene synthase cDNAs from S. lycopersicum and five from S. habrochaites. Searches of other databases and the S. lycopersicum genome resulted in the discovery of two additional sesquiterpene synthases expressed in trichomes. The sesquiterpene synthases from S. lycopersicum and S. habrochaites have high levels of protein identity. Several of them appeared to encode for non-functional proteins. Functional recombinant proteins produced germacrenes, β-caryophyllene/α-humulene, viridiflorene and valencene from (E,E)-farnesyl diphosphate. However, the activities of these enzymes do not completely explain the differences in sesquiterpene production between the two tomato plants. RT-qPCR confirmed high levels of expression of most of the S. lycopersicum sesquiterpene synthases in stem trichomes. In addition, one sesquiterpene synthase was induced by jasmonic acid, while another appeared to be slightly repressed by the treatment. Our data provide a foundation to study the evolution of terpene synthases in cultivated and wild tomato

The tomato terpene synthase gene family

Compounds of the terpenoid class play numerous roles in the interactions of plants with their environment, such as attracting pollinators and defending the plant against pests. We show here that the genome of cultivated tomato (Solanum lycopersicum) contains 44 terpene synthase (TPS) genes, including 29 that are functional or potentially functional. Of these 29 TPS genes, 26 were expressed in at least some organs or tissues of the plant. The enzymatic functions of eight of the TPS proteins were previously reported, and here we report the specific in vitro catalytic activity of 10 additional tomato terpene synthases. Many of the tomato TPS genes are found in clusters, notably on chromosomes 1, 2, 6, 8, and 10. All TPS family clades previously identified in angiosperms are also present in tomato. The largest clade of functional TPS genes found in tomato, with 12 members, is the TPS-a clade, and it appears to encode only sesquiterpene synthases, one of which is localized to the mitochondria, while the rest are likely cytosolic. A few additional sesquiterpene synthases are encoded by TPS-b clade genes. Some of the tomato sesquiterpene synthases use z,z-farnesyl diphosphate in vitro as well, or more efficiently than, the e,e-farnesyl diphosphate substrate. Genes encoding monoterpene synthases are also prevalent, and they fall into three clades: TPS-b, TPS-g, and TPS-e/f. With the exception of two enzymes involved in the synthesis of ent-kaurene, the precursor of gibberellins, no other tomato TPS genes could be demonstrated to encode diterpene synthases so far

The tomato cis– prenyltransferase gene family

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/1/tpj12063-sup-0004-FigureS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/2/tpj12063-sup-0005-FigureS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/3/tpj12063-sup-0002-FigureS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/4/tpj12063-sup-0003-FigureS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/5/tpj12063-sup-0001-FigureS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/6/tpj12063.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96709/7/tpj12063-sup-0006-TableS1.pd

Geranyllinalool Synthases in Solanaceae and Other Angiosperms Constitute an Ancient Branch of Diterpene Synthases Involved in the Synthesis of Defensive Compounds

Many angiosperm plants, including basal dicots, eudicots, and monocots, emit (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene, which is derived from geranyllinalool, in response to biotic challenge. An Arabidopsis (Arabidopsis thaliana) geranyllinalool synthase (GLS) belonging to the e/f clade of the terpene synthase (TPS) family and two Fabaceae GLSs that belong to the TPS-g clade have been reported, making it unclear which is the main route to geranyllinalool in plants. We characterized a tomato (Solanum lycopersicum) TPS-e/f gene, TPS46, encoding GLS (SlGLS) and its homolog (NaGLS) from Nicotiana attenuata. The Km value of SlGLS for geranylgeranyl diphosphate was 18.7 microm, with a turnover rate value of 6.85 s(-1). In leaves and flowers of N. attenuata, which constitutively synthesize 17-hydroxygeranyllinalool glycosides, NaGLS is expressed constitutively, but the gene can be induced in leaves with methyl jasmonate. In tomato, SlGLS is not expressed in any tissue under normal growth but is induced in leaves by alamethicin and methyl jasmonate treatments. SlGLS, NaGLS, AtGLSs, and several other GLSs characterized only in vitro come from four different eudicot families and constitute a separate branch of the TPS-e/f clade that diverged from kaurene synthases, also in the TPS-e/f clade, before the gymnosperm-angiosperm split. The early divergence of this branch and the GLS activity of genes in this branch in diverse eudicot families suggest that GLS activity encoded by these genes predates the angiosperm-gymnosperm split. However, although a TPS sequence belonging to this GLS lineage was recently reported from a basal dicot, no representative sequences have yet been found in monocot or nonangiospermous plants

Transcriptomic Signatures of Ash (Fraxinus spp.) Phloem

Ash (Fraxinus spp.) is a dominant tree species throughout urban and forested landscapes of North America (NA). The rapid invasion of NA by emerald ash borer (Agrilus planipennis), a wood-boring beetle endemic to Eastern Asia, has resulted in the death of millions of ash trees and threatens billions more. Larvae feed primarily on phloem tissue, which girdles and kills the tree. While NA ash species including black (F. nigra), green (F. pennsylvannica) and white (F. americana) are highly susceptible, the Asian species Manchurian ash (F. mandshurica) is resistant to A. planipennis perhaps due to their co-evolutionary history. Little is known about the molecular genetics of ash. Hence, we undertook a functional genomics approach to identify the repertoire of genes expressed in ash phloem.Using 454 pyrosequencing we obtained 58,673 high quality ash sequences from pooled phloem samples of green, white, black, blue and Manchurian ash. Intriguingly, 45% of the deduced proteins were not significantly similar to any sequences in the GenBank non-redundant database. KEGG analysis of the ash sequences revealed a high occurrence of defense related genes. Expression analysis of early regulators potentially involved in plant defense (i.e. transcription factors, calcium dependent protein kinases and a lipoxygenase 3) revealed higher mRNA levels in resistant ash compared to susceptible ash species. Lastly, we predicted a total of 1,272 single nucleotide polymorphisms and 980 microsatellite loci, among which seven microsatellite loci showed polymorphism between different ash species.The current transcriptomic data provide an invaluable resource for understanding the genetic make-up of ash phloem, the target tissue of A. planipennis. These data along with future functional studies could lead to the identification/characterization of defense genes involved in resistance of ash to A. planipennis, and in future ash breeding programs for marker development