The study of the elasticity of spider dragline silk with liquid crystal model

International Nuclear Information System (INIS)

Cui Linying; Liu Fei; Ouyang Zhongcan

2009-01-01

Spider dragline silk is an optimal biomaterial with a combination of high tensile strength and high elasticity, and it has long been suggested to belong to liquid crystalline materials. However, a satisfactory liquid crystal description for the mechanical properties of the dragline is still missing. To solve the long existing problem, we generalized the Maier-Saupe theory of nematics to construct a liquid crystal model of the deformation mechanism of the dragline silk. We show that the remarkable elasticity of the dragline can be understood as the isotropic-nematic phase transition of the chain network with the beginning of the transition corresponding to the yield point. The calculated curve fits well with the measurements and the yield point is obtained self-consistently within our framework. The present theory can also qualitatively account for the drop of stress in supercontracted spider silk. All these comprehensive agreements between theory and experiments strongly indicate the dragline to belong to liquid crystal materials.

In Vitro Evaluation of Spider Silk Meshes as a Potential Biomaterial for Bladder Reconstruction

NARCIS (Netherlands)

Steins, A.; Dik, P.; Müller, W.H.; Vervoort, S.J.; Reimers, K.; Kubhier, J.W.; Vogt, P.M.; van Apeldoorn, Aart A.; Coffer, P.J.; Schepers, K.

2015-01-01

Reconstruction of the bladder by means of both natural and synthetic materials remains a challenge due to severe adverse effects such as mechanical failure. Here we investigate the application of spider major ampullate gland-derived dragline silk from the Nephila edulis spider, a natural biomaterial

A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China.

Science.gov (United States)

Selden, Paul A; Shih, ChungKun; Ren, Dong

2011-10-23

Nephila are large, conspicuous weavers of orb webs composed of golden silk, in tropical and subtropical regions. Nephilids have a sparse fossil record, the oldest described hitherto being Cretaraneus vilaltae from the Cretaceous of Spain. Five species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strata of Daohugou, Inner Mongolia, China. The new species extends the fossil record of the family by approximately 35 Ma and of the genus Nephila by approximately 130 Ma, making it the longest ranging spider genus known. Nephilidae originated somewhere on Pangaea, possibly the North China block, followed by dispersal almost worldwide before the break-up of the supercontinent later in the Mesozoic. The find suggests that the palaeoclimate was warm and humid at this time. This giant fossil orb-weaver provides evidence of predation on medium to large insects, well known from the Daohugou beds, and would have played an important role in the evolution of these insects.

Application of Machine Learning for Dragline Failure Prediction

Directory of Open Access Journals (Sweden)

Taghizadeh Amir

2017-01-01

Full Text Available Overburden stripping in open cast coal mines is extensively carried out by walking draglines. Draglines’ unavailability and unexpected failures result in delayed productions and increased maintenance and operating costs. Therefore, achieving high availability of draglines plays a crucial role for increasing economic feasibility of mining projects. Applications of methodologies which can forecast the failure type of dragline based on the available failure data not only help to reduce the maintenance and operating costs but also increase the availability and the production rate. In this study, Machine Learning approaches have been applied for data which has been gathered from an operating coal mine in Turkey. The study methodology consists of three algorithms as: i implementation of K-Nearest Neighbors, ii implementation of Multi-Layer Perceptron, and iii implementation of Radial Basis Function. The algorithms have been utilized for predicting the draglines’ failure types. In this sense, the input data, which are mean time-to-failure, and the output data, failure types, have been fed to the algorithms. The regression analysis of methodologies have been compared and showed the K- Nearest Neighbors has a higher rate of regression which is around 70 percent. Thus, the K-Nearest Neighbor algorithm can be applied in order to preventive components replacement which causes to minimized preventive and corrective cost parameters. The accurate prediction of failure type, indeed, causes to optimized number of inspections. The novelty of this study is application of machine learning approaches in draglines’ reliability subject for first time.

Complex gene expression in the dragline silk producing glands of the Western black widow (Latrodectus hesperus).

Science.gov (United States)

Lane, Amanda Kelly; Hayashi, Cheryl Y; Whitworth, Gregg B; Ayoub, Nadia A

2013-12-02

Orb-web and cob-web weaving spiders spin dragline silk fibers that are among the strongest materials known. Draglines are primarily composed of MaSp1 and MaSp2, two spidroins (spider fibrous proteins) expressed in the major ampullate (MA) silk glands. Prior genetic studies of dragline silk have focused mostly on determining the sequence of these spidroins, leaving other genetic aspects of silk synthesis largely uncharacterized. Here, we used deep sequencing to profile gene expression patterns in the Western black widow, Latrodectus hesperus. We sequenced millions of 3'-anchored "tags" of cDNAs derived either from MA glands or control tissue (cephalothorax) mRNAs, then associated the tags with genes by compiling a reference database from our newly constructed normalized L. hesperus cDNA library and published L. hesperus sequences. We were able to determine transcript abundance and alternative polyadenylation of each of three loci encoding MaSp1. The ratio of MaSp1:MaSp2 transcripts varied between individuals, but on average was similar to the estimated ratio of MaSp1:MaSp2 in dragline fibers. We also identified transcription of TuSp1 in MA glands, another spidroin family member that encodes the primary component of egg-sac silk, synthesized in tubuliform glands. In addition to the spidroin paralogs, we identified 30 genes that are more abundantly represented in MA glands than cephalothoraxes and represent new candidates for involvement in spider silk synthesis. Modulating expression rates of MaSp1 variants as well as MaSp2 and TuSp1 could lead to differences in mechanical properties of dragline fibers. Many of the newly identified candidate genes likely encode secreted proteins, suggesting they could be incorporated into dragline fibers or assist in protein processing and fiber assembly. Our results demonstrate previously unrecognized transcript complexity in spider silk glands.

Phylogeography of a successful aerial disperser: the golden orb spider Nephila on Indian Ocean islands

Directory of Open Access Journals (Sweden)

Kuntner Matjaž

2011-05-01

Full Text Available Abstract Background The origin and diversification patterns of lineages across the Indian Ocean islands are varied due to the interplay of the complex geographic and geologic island histories, the varying dispersal abilities of biotas, and the proximity to major continental landmasses. Our aim was to reconstruct phylogeographic history of the giant orbweaving spider (Nephila on western Indian Ocean islands (Madagascar, Mayotte, Réunion, Mauritius, Rodrigues, to test its origin and route of dispersal, and to examine the consequences of good dispersal abilities for colonization and diversification, in comparison with related spiders (Nephilengys inhabiting the same islands, and with other organisms known for over water dispersal. We used mitochondrial (COI and nuclear (ITS2 markers to examine phylogenetic and population genetic patterns in Nephila populations and species. We employed Bayesian and parsimony methods to reconstruct phylogenies and haplotype networks, respectively, and calculated genetic distances, fixation indices, and estimated clade ages under a relaxed clock model. Results Our results suggest an African origin of Madagascar Nephila inaurata populations via Cenozoic dispersal, and the colonization of the Mascarene islands from Madagascar. We find evidence of gene flow across Madagascar and Comoros. The Mascarene islands share a common 'ancestral' COI haplotype closely related to those found on Madagascar, but itself absent, or as yet unsampled, from Madagascar. Each island has one or more unique haplotypes related to the ancestral Mascarene haplotype. The Indian Ocean N. inaurata are genetically distinct from the African populations. Conclusions Nephila spiders colonized Madagascar from Africa about 2.5 (0.6-5.3 Ma. Our results are consistent with subsequent, recent and rapid, colonization of all three Mascarene islands. On each island, however, we detected unique haplotypes, consistent with a limited gene flow among the islands

Artificial skin--culturing of different skin cell lines for generating an artificial skin substitute on cross-weaved spider silk fibres.

Directory of Open Access Journals (Sweden)

Hanna Wendt

Full Text Available BACKGROUND: In the field of Plastic Reconstructive Surgery the development of new innovative matrices for skin repair is in urgent need. The ideal biomaterial should promote attachment, proliferation and growth of cells. Additionally, it should degrade in an appropriate time period without releasing harmful substances, but not exert a pathological immune response. Spider dragline silk from Nephila spp meets these demands to a large extent. METHODOLOGY/PRINCIPAL FINDINGS: Native spider dragline silk, harvested directly out of Nephila spp spiders, was woven on steel frames. Constructs were sterilized and seeded with fibroblasts. After two weeks of cultivating single fibroblasts, keratinocytes were added to generate a bilayered skin model, consisting of dermis and epidermis equivalents. For the next three weeks, constructs in co-culture were lifted on an originally designed setup for air/liquid interface cultivation. After the culturing period, constructs were embedded in paraffin with an especially developed program for spidersilk to avoid supercontraction. Paraffin cross-sections were stained in Haematoxylin & Eosin (H&E for microscopic analyses. CONCLUSION/SIGNIFICANCE: Native spider dragline silk woven on steel frames provides a suitable matrix for 3 dimensional skin cell culturing. Both fibroblasts and keratinocytes cell lines adhere to the spider silk fibres and proliferate. Guided by the spider silk fibres, they sprout into the meshes and reach confluence in at most one week. A well-balanced, bilayered cocultivation in two continuously separated strata can be achieved by serum reduction, changing the medium conditions and the cultivation period at the air/liquid interphase. Therefore spider silk appears to be a promising biomaterial for the enhancement of skin regeneration.

Life history trade-offs imposed by dragline use in two money spiders.

Science.gov (United States)

Bonte, Dries; Verduyn, Lieselot; Braeckman, Bart P

2016-01-01

Trade-offs among life history traits are central to understanding the limits of adaptations to stress. In animals, virtually all decisions taken during life are expected to have downstream consequences. To what degree rare, but energy-demanding, decisions carry over to individual performance is rarely studied in arthropods. We used spiders as a model system to test how single investments in silk use - for dispersal or predator escape - affect individual performance. Silk produced for safe lines and as threads for ballooning is of the strongest kind and is energetically costly, especially when resources are limited. We induced dragline spinning in two species of money spider at similar quantities to that under natural conditions and tested trade-offs with lifespan and egg sac production under unlimited prey availability and a dietary restriction treatment. We demonstrate strong trade-offs between dragline spinning and survival and fecundity. Survival trade-offs were additive to those imposed by the dietary treatment, but a reduction in eggs produced after silk use was only prevalent under conditions where food was restricted during the spider's life. Because draglines are not recycled after their use for dispersal or predator escape, their spinning incurs substantial fitness costs in dispersal, especially in environments with prey limitation. Rare but energetically costly decisions related to dispersal or predator escape may thus carry over to adult performance and explain phenotypic heterogeneity in natural populations. © 2016. Published by The Company of Biologists Ltd.

Secondary Structure Adopted by the Gly-Gly-X Repetitive Regions of Dragline Spider Silk

Directory of Open Access Journals (Sweden)

Geoffrey M. Gray

2016-12-01

Full Text Available Solid-state NMR and molecular dynamics (MD simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X, which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X regions of dragline silks, including β-turns, 310-helicies, and coil structures with a negligible population of α-helix observed.

Plastic material investment in load-bearing silk attachments in spiders.

Science.gov (United States)

Wolff, Jonas O; Jones, Braxton; Herberstein, Marie E

2018-05-17

The nature and size of attachments is a fundamental element of animal constructions. Presumably, these adhesive structures are plastically deployed to balance material investment and attachment strength. Here we studied plasticity in dragline anchorages of the golden orb web spider, Nephila plumipes. Specifically, we predict that spiders adjust the size and structure of dragline anchorages with load, i.e. spider mass. Mass was manipulated by attaching lead pieces to the spider's abdomen resulting in a 50 percent increase in mass. Loaded spiders spun larger but structurally similar thread anchorages than unloaded spiders. Thus, the spinning program that determines the overall anchor structure is highly stereotypic, and flexibility is introduced through varying the anchor size by increasing material investment. Our study showcases substrate attachments as suitable models to investigate the interplay between innate and changeable elements in the economy of building behaviours. Copyright © 2018 Elsevier GmbH. All rights reserved.

Mechanical properties of silk of the Australian golden orb weavers Nephila pilipes and Nephilaplumipes.

Science.gov (United States)

Kerr, Genevieve G; Nahrung, Helen F; Wiegand, Aaron; Kristoffersen, Joanna; Killen, Peter; Brown, Cameron; Macdonald, Joanne

2018-02-22

Silks from orb-weaving spiders are exceptionally tough, producing a model polymer for biomimetic fibre development. The mechanical properties of naturally spun silk threads from two species of Australian orb-weavers, Nephila pilipes and Nephila plumipes , were examined here in relation to overall thread diameter, the size and number of fibres within threads, and spider size. N. pilipes , the larger of the two species, had significantly tougher silk with higher strain capacity than its smaller congener, producing threads with average toughness of 150 MJ m -3 , despite thread diameter, mean fibre diameter and number of fibres per thread not differing significantly between the two species. Within N. pilipes , smaller silk fibres were produced by larger spiders, yielding tougher threads. In contrast, while spider size was correlated with thread diameter in N. plumipes , there were no clear patterns relating to silk toughness, which suggests that the differences in properties between the silk of the two species arise through differing molecular structure. Our results support previous studies that found that the mechanical properties of silk differ between distantly related spider species, and extends on that work to show that the mechanical and physical properties of silk from more closely related species can also differ remarkably. © 2018. Published by The Company of Biologists Ltd.

Structure determination of spider silk from X-ray images

Energy Technology Data Exchange (ETDEWEB)

Ulrich, Stephan; Zippelius, Annette [Universitaet Goettingen, Institut fuer Theoretische Physik (Germany); Meling, Martin [Max-Planck-Institut fuer biophysikalische Chemie, Goettingen (Germany); Glisovic, Anja; Salditt, Tim [Universitaet Goettingen, Institut fuer Roentgenphysik (Germany)

2008-07-01

Spider silk consists of interconnected crystallites, which are typically aligned along the fiber axis. We present a method to systematically determine the structure of these crystallites. Hereby we introduce a model that calculates the scattering function G(q) which is fitted to the measured X-ray image (silk from nephila clavipes). With it, the crystallites' size, the constitution and dimensions of their unit cell, as well as their tilt with respect to the fiber axis is identified, and furthermore the effect of coherent scattering from different crystallites is investigated. The shown methods and the presented model can easily be generalized to a wide class of composite materials.

Solid-phase synthesis and biological evaluation of Joro spider toxin-4 from Nephila clavata

DEFF Research Database (Denmark)

Barslund, Anne Fuglsang; Poulsen, Mette Homann; Bach, Tinna Brøbech

2011-01-01

Polyamine toxins from orb weaver spiders are attractive pharmacological tools particularly for studies of ionotropic glutamate (iGlu) receptors in the brain. These polyamine toxins are biosynthesized in a combinatorial manner, providing a plethora of related, but structurally complex toxins...... to be exploited in biological studies. Here, we have used solid-phase synthetic methodology for the efficient synthesis of Joro spider toxin-4 (JSTX-4) (1) from Nephila clavata, providing sufficient amounts of the toxin for biological evaluation at iGlu receptor subtypes using electrophysiology. Biological...

A molecular phylogeny of nephilid spiders: evolutionary history of a model lineage.

Science.gov (United States)

Kuntner, Matjaž; Arnedo, Miquel A; Trontelj, Peter; Lokovšek, Tjaša; Agnarsson, Ingi

2013-12-01

The pantropical orb web spider family Nephilidae is known for the most extreme sexual size dimorphism among terrestrial animals. Numerous studies have made Nephilidae, particularly Nephila, a model lineage in evolutionary research. However, a poorly understood phylogeny of this lineage, relying only on morphology, has prevented thorough evolutionary syntheses of nephilid biology. We here use three nuclear and five mitochondrial genes for 28 out of 40 nephilid species to provide a more robust nephilid phylogeny and infer clade ages in a fossil-calibrated Bayesian framework. We complement the molecular analyses with total evidence analysis including morphology. All analyses find strong support for nephilid monophyly and exclusivity and the monophyly of the genera Herennia and Clitaetra. The inferred phylogenetic structure within Nephilidae is novel and conflicts with morphological phylogeny and traditional taxonomy. Nephilengys species fall into two clades, one with Australasian species (true Nephilengys) as sister to Herennia, and another with Afrotropical species (Nephilingis Kuntner new genus) as sister to a clade containing Clitaetra plus most currently described Nephila. Surprisingly, Nephila is also diphyletic, with true Nephila containing N. pilipes+N. constricta, and the second clade with all other species sister to Clitaetra; this "Nephila" clade is further split into an Australasian clade that also contains the South American N. sexpunctata and the Eurasian N. clavata, and an African clade that also contains the Panamerican N. clavipes. An approximately unbiased test constraining the monophyly of Nephilengys, Nephila, and Nephilinae (Nephila, Nephilengys, Herennia), respectively, rejected Nephilengys monophyly, but not that of Nephila and Nephilinae. Further data are therefore necessary to robustly test these two new, but inconclusive findings, and also to further test the precise placement of Nephilidae within the Araneoidea. For divergence date estimation

An insecticidal toxin from Nephila clavata spider venom.

Science.gov (United States)

Jin, Lin; Fang, Mingqian; Chen, Mengrou; Zhou, Chunling; Ombati, Rose; Hakim, Md Abdul; Mo, Guoxiang; Lai, Ren; Yan, Xiuwen; Wang, Yumin; Yang, Shilong

2017-07-01

Spiders are the most successful insect predators given that they use their venom containing insecticidal peptides as biochemical weapons for preying. Due to the high specificity and potency of peptidic toxins, discoveries of insecticidal toxins from spider venom have provided an opportunity to obtain natural compounds for agricultural applications without affecting human health. In this study, a novel insecticidal toxin (μ-NPTX-Nc1a) was identified and characterized from the venom of Nephila clavata. Its primary sequence is GCNPDCTGIQCGWPRCPGGQNPVMDKCVSCCPFCPPKSAQG which was determined by automated Edman degradation, cDNA cloning, and MS/MS analysis. BLAST search indicated that Nc1a shows no similarity with known peptides or proteins, indicating that Nc1a belongs to a novel family of insecticidal peptide. Nc1a displayed inhibitory effects on Na V and K V channels in cockroach dorsal unpaired median neurons. The median lethal dose (LD50) of Nc1a on cockroach was 573 ng/g. Herein, a study that identifies a novel insecticidal toxin, which can be a potential candidate and/or template for the development of bioinsecticides, is presented.

Chromosome mapping of dragline silk genes in the genomes of widow spiders (Araneae, Theridiidae.

Directory of Open Access Journals (Sweden)

Yonghui Zhao

Full Text Available With its incredible strength and toughness, spider dragline silk is widely lauded for its impressive material properties. Dragline silk is composed of two structural proteins, MaSp1 and MaSp2, which are encoded by members of the spidroin gene family. While previous studies have characterized the genes that encode the constituent proteins of spider silks, nothing is known about the physical location of these genes. We determined karyotypes and sex chromosome organization for the widow spiders, Latrodectus hesperus and L. geometricus (Araneae, Theridiidae. We then used fluorescence in situ hybridization to map the genomic locations of the genes for the silk proteins that compose the remarkable spider dragline. These genes included three loci for the MaSp1 protein and the single locus for the MaSp2 protein. In addition, we mapped a MaSp1 pseudogene. All the MaSp1 gene copies and pseudogene localized to a single chromosomal region while MaSp2 was located on a different chromosome of L. hesperus. Using probes derived from L. hesperus, we comparatively mapped all three MaSp1 loci to a single region of a L. geometricus chromosome. As with L. hesperus, MaSp2 was found on a separate L. geometricus chromosome, thus again unlinked to the MaSp1 loci. These results indicate orthology of the corresponding chromosomal regions in the two widow genomes. Moreover, the occurrence of multiple MaSp1 loci in a conserved gene cluster across species suggests that MaSp1 proliferated by tandem duplication in a common ancestor of L. geometricus and L. hesperus. Unequal crossover events during recombination could have given rise to the gene copies and could also maintain sequence similarity among gene copies over time. Further comparative mapping with taxa of increasing divergence from Latrodectus will pinpoint when the MaSp1 duplication events occurred and the phylogenetic distribution of silk gene linkage patterns.

KERAGAMAN SERANGGA PADA TANAMAN CABAI (CAPSICUM ANNUUM YANG DIBERI PESTISIDA SINTETIS VERSUS BIOPESTISIDA RACUN LABA-LABA (NEPHILA SP.

Directory of Open Access Journals (Sweden)

Yayan Sanjaya

2013-09-01

Full Text Available The objective of this research was to compare the diversity of insects in chili plant agroecosystem treated with synthetic pesticide versus that treated with biopesticide (venom of spider Nephila sp. Two plots of chili pepper plants, each sized 600 m2, located at Ciwidey area Bandung –West Java, were taken as the sample plots. The first plot was weekly treated with profenofos insecticide (50% active ingredient, a.i. while the second plot was treated with  biopesticide (70% a.i. spider venom extracted from Nephila sp., each at 35 ml/17 L rate of spray solution. Sweep net was used to sample insects along two transects in each plot. Result showed that 14 families of 8 insect orders were found in pesticide-treated plot while 15 families of  9 orders were found in biopesticide-treated plot. The evenness index and diversity index of insects in plot treated with biopesticide were relatively higher than those in pesticide-treated plot. In contrast, dominance index in biopesticide plot was lower than that in synthetic pesticide plot. Thrips sp.(Thysanoptera: Thripidae was found to be the most dominant species in both plots.

Characterizing the Secondary Protein Structure of Black Widow Dragline Silk Using Solid-State NMR & X-ray Diffraction

Science.gov (United States)

Jenkins, Janelle E.; Sampath, Sujatha; Butler, Emily; Kim, Jihyun; Henning, Robert W.; Holland, Gregory P.; Yarger, Jeffery L.

2013-01-01

This study provides a detailed secondary structural characterization of major ampullate dragline silk from Latrodectus hesperus (black widow) spiders. X-ray diffraction results show that the structure of black widow major ampullate silk fibers is comprised of stacked β-sheet nanocrystallites oriented parallel to the fiber axis and an amorphous region with oriented (anisotropic) and isotropic components. The combination of two-dimensional (2D) 13C-13C through-space and through-bond solid-state NMR experiments provide chemical shifts that are used to determine detailed information about amino acid motif secondary structure in black widow spider dragline silk. Individual amino acids are incorporated into different repetitive motifs that make up the majority of this protein-based biopolymer. From the solid-state NMR measurements, we assign distinct secondary conformations to each repetitive amino acid motif and hence to the amino acids that make up the motifs. Specifically, alanine is incorporated in β-sheet (poly(Alan) and poly(Gly-Ala)), 31-helix (poly(Gly-Gly-Xaa), and α-helix (poly(Gln-Gln-Ala-Tyr)) components. Glycine is determined to be in β-sheet (poly(Gly-Ala)) and 31-helical (poly(Gly-Gly-Xaa)) regions, while serine is present in β-sheet (poly(Gly-Ala-Ser)), 31-helix (poly(Gly-Gly-Ser)), and β-turn (poly(Gly-Pro-Ser)) structures. These various motif-specific secondary structural elements are quantitatively correlated to the primary amino acid sequence of major ampullate spidroin 1 and 2 (MaSp1 and MaSp2) and are shown to form a self-consistent model for black widow dragline silk. PMID:24024617

Nutrient Deprivation Induces Property Variations in Spider Gluey Silk

Science.gov (United States)

Blamires, Sean J.; Sahni, Vasav; Dhinojwala, Ali; Blackledge, Todd A.; Tso, I-Min

2014-01-01

Understanding the mechanisms facilitating property variability in biological adhesives may promote biomimetic innovations. Spider gluey silks such as the spiral threads in orb webs and the gumfoot threads in cobwebs, both of which comprise of an axial thread coated by glue, are biological adhesives that have variable physical and chemical properties. Studies show that the physical and chemical properties of orb web gluey threads change when spiders are deprived of food. It is, however, unknown whether gumfoot threads undergo similar property variations when under nutritional stress. Here we tested whether protein deprivation induces similar variations in spiral and gumfoot thread morphology and stickiness. We manipulated protein intake for the orb web spider Nephila clavipes and the cobweb spider Latrodectus hesperus and measured the diameter, glue droplet volume, number of droplets per mm, axial thread width, thread stickiness and adhesive energy of their gluey silks. We found that the gluey silks of both species were stickier when the spiders were deprived of protein than when the spiders were fed protein. In N. clavipes a concomitant increase in glue droplet volume was found. Load-extension curves showed that protein deprivation induced glue property variations independent of the axial thread extensions in both species. We predicted that changes in salt composition of the glues were primarily responsible for the changes in stickiness of the silks, although changes in axial thread properties might also contribute. We, additionally, showed that N. clavipes' glue changes color under protein deprivation, probably as a consequence of changes to its biochemical composition. PMID:24523902

Chitin in the Silk Gland Ducts of the Spider Nephila edulis and the Silkworm Bombyx mori

Science.gov (United States)

Davies, Gwilym J. G.; Knight, David P.; Vollrath, Fritz

2013-01-01

Here we report the detection and localisation of chitin in the cuticle of the spinning ducts of both the spider Nephila edulis and the silkworm Bombyx mori. Our observations demonstrate that the duct walls of both animals contain chitin notwithstanding totally independent evolutionary pathways of the systems. We conclude that chitin may well be an essential component for the construction of spinning ducts; we further conclude that in both species chitin may indicate the evolutionary origin of the spinning ducts. PMID:24015298

Control of silicification by genetically engineered fusion proteins: Silk–silica binding peptides

Science.gov (United States)

Zhou, Shun; Huang, Wenwen; Belton, David J.; Simmons, Leo O.; Perry, Carole C.; Wang, Xiaoqin; Kaplan, David L.

2014-01-01

In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk–silica composite in two different bioinspired silicification systems: solution–solution and solution– solid. Condensed silica nanoscale particles (600–800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras [1], revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution–solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer–silica composites for biomaterial related needs. PMID:25462851

Control of silicification by genetically engineered fusion proteins: silk-silica binding peptides.

Science.gov (United States)

Zhou, Shun; Huang, Wenwen; Belton, David J; Simmons, Leo O; Perry, Carole C; Wang, Xiaoqin; Kaplan, David L

2015-03-01

In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk-silica composite in two different bioinspired silicification systems: solution-solution and solution-solid. Condensed silica nanoscale particles (600-800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras, revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution-solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer-silica composites for biomaterial related needs. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hybrid carbon nanotube yarn artificial muscle inspired by spider dragline silk.

Science.gov (United States)

Chun, Kyoung-Yong; Hyeong Kim, Shi; Kyoon Shin, Min; Hoon Kwon, Cheong; Park, Jihwang; Tae Kim, Youn; Spinks, Geoffrey M; Lima, Márcio D; Haines, Carter S; Baughman, Ray H; Jeong Kim, Seon

2014-01-01

Torsional artificial muscles generating fast, large-angle rotation have been recently demonstrated, which exploit the helical configuration of twist-spun carbon nanotube yarns. These wax-infiltrated, electrothermally powered artificial muscles are torsionally underdamped, thereby experiencing dynamic oscillations that complicate positional control. Here, using the strategy spiders deploy to eliminate uncontrolled spinning at the end of dragline silk, we have developed ultrafast hybrid carbon nanotube yarn muscles that generated a 9,800 r.p.m. rotation without noticeable oscillation. A high-loss viscoelastic material, comprising paraffin wax and polystyrene-poly(ethylene-butylene)-polystyrene copolymer, was used as yarn guest to give an overdamped dynamic response. Using more than 10-fold decrease in mechanical stabilization time, compared with previous nanotube yarn torsional muscles, dynamic mirror positioning that is both fast and accurate is demonstrated. Scalability to provide constant volumetric torsional work capacity is demonstrated over a 10-fold change in yarn cross-sectional area, which is important for upscaled applications.

Non-invasive determination of the complete elastic moduli of spider silks

Science.gov (United States)

Koski, Kristie J.; Akhenblit, Paul; McKiernan, Keri; Yarger, Jeffery L.

2013-03-01

Spider silks possess nature’s most exceptional mechanical properties, with unrivalled extensibility and high tensile strength. Unfortunately, our understanding of silks is limited because the complete elastic response has never been measured—leaving a stark lack of essential fundamental information. Using non-invasive, non-destructive Brillouin light scattering, we obtain the entire stiffness tensors (revealing negative Poisson’s ratios), refractive indices, and longitudinal and transverse sound velocities for major and minor ampullate spider silks: Argiope aurantia, Latrodectus hesperus, Nephila clavipes, Peucetia viridans. These results completely quantify the linear elastic response for all possible deformation modes, information unobtainable with traditional stress-strain tests. For completeness, we apply the principles of Brillouin imaging to spatially map the elastic stiffnesses on a spider web without deforming or disrupting the web in a non-invasive, non-contact measurement, finding variation among discrete fibres, junctions and glue spots. Finally, we provide the stiffness changes that occur with supercontraction.

Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques.

Science.gov (United States)

Munro, Troy; Putzeys, Tristan; Copeland, Cameron G; Xing, Changhu; Lewis, Randolph V; Ban, Heng; Glorieux, Christ; Wubbenhorst, Michael

2017-04-01

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production.

In vitro radiation protection of peripheral blood mononuclear cells by Tetragona Clavipes Propolis

Energy Technology Data Exchange (ETDEWEB)

Nogueira, Naira de Souza Gomes [Universidade Federal do Amazonas (ICET/UFAM), Manaus (Brazil). Instituto de Ciências Exatas e Tecnologia; Campos, Tarcísio Passos Ribeiro; Montaño Valencia, Carlos Julio; Falcão, Patrícia Lima [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Técnicas Nucleares

2017-07-01

Background: Research in breast cancer has shown notable relevance in recent years, bringing serious concern on the public health policies due to its high incidence and mortality, especially in Brazil. Limitations due to the toxic effects in the normal tissues and the depletion in the immune system have often been present in the breast cancer radiotherapy and chemotherapy. It is a promise a drug development of vegetal origin that induce immune system protection in patients submitted to radiotherapy and chemotherapy, if such compounds inhibit the depletion of the circulating cell number. Objectives: To evaluate the in vitro effect of the extract of Tetragona Clavipes Propolis (TCP) in the viability of the human Peripheral Blood Mononuclear Cells (PBMC). Methods: The non-irradiated control, the irradiated control and the radiated and exposed to TCP (n=3) (GIE) groups were established. The cells were irradiated with predetermined doses of 2 and 5Gy, supplemented with TCP-extracts in aqueous solution at concentrations of 0.5, 1, 5 and 10 %. Post-irradiated sample was collected and viability assay was carried out at the time of 24, 48 and 72h. Results: A significant decrease of PBMC viability was observed after 2 and 5Gy. However, GIE showed an increase of cell viability, especially in the 5 and 10% concentrations of the extract incubated in culture, even after 5Gy. Conclusions: The findings showed that the aqueous extract of TCP is an exogenous protective agent to irradiated PBMC. This study opens a relevant perspective on the role of Propolis use as an adjuvant agent in protecting the immune system of patients undergoing breast radiotherapy. (author)

In vitro radiation protection of peripheral blood mononuclear cells by Tetragona Clavipes Propolis

International Nuclear Information System (INIS)

Nogueira, Naira de Souza Gomes; Campos, Tarcísio Passos Ribeiro; Montaño Valencia, Carlos Julio; Falcão, Patrícia Lima

2017-01-01

Background: Research in breast cancer has shown notable relevance in recent years, bringing serious concern on the public health policies due to its high incidence and mortality, especially in Brazil. Limitations due to the toxic effects in the normal tissues and the depletion in the immune system have often been present in the breast cancer radiotherapy and chemotherapy. It is a promise a drug development of vegetal origin that induce immune system protection in patients submitted to radiotherapy and chemotherapy, if such compounds inhibit the depletion of the circulating cell number. Objectives: To evaluate the in vitro effect of the extract of Tetragona Clavipes Propolis (TCP) in the viability of the human Peripheral Blood Mononuclear Cells (PBMC). Methods: The non-irradiated control, the irradiated control and the radiated and exposed to TCP (n=3) (GIE) groups were established. The cells were irradiated with predetermined doses of 2 and 5Gy, supplemented with TCP-extracts in aqueous solution at concentrations of 0.5, 1, 5 and 10 %. Post-irradiated sample was collected and viability assay was carried out at the time of 24, 48 and 72h. Results: A significant decrease of PBMC viability was observed after 2 and 5Gy. However, GIE showed an increase of cell viability, especially in the 5 and 10% concentrations of the extract incubated in culture, even after 5Gy. Conclusions: The findings showed that the aqueous extract of TCP is an exogenous protective agent to irradiated PBMC. This study opens a relevant perspective on the role of Propolis use as an adjuvant agent in protecting the immune system of patients undergoing breast radiotherapy. (author)

Nutrient intake determines post-maturity molting in the golden orb-web spider Nephila pilipes (Araneae: Araneidae).

Science.gov (United States)

Cheng, Ren-Chung; Zhang, Shichang; Chen, Yu-Chun; Lee, Chia-Yi; Chou, Yi-Ling; Ye, Hui-Ying; Piorkowski, Dakota; Liao, Chen-Pan; Tso, I-Min

2017-06-15

While molting occurs in the development of many animals, especially arthropods, post-maturity molting (PMM, organisms continue to molt after sexual maturity) has received little attention. The mechanism of molting has been studied intensively; however, the mechanism of PMM remains unknown although it is suggested to be crucial for the development of body size. In this study, we investigated factors that potentially induce PMM in the golden orb-web spider Nephila pilipes , which has the greatest degree of sexual dimorphism among terrestrial animals. We manipulated the mating history and the nutrient consumption of the females to examine whether they affect PMM. The results showed that female spiders under low nutrition were more likely to molt as adults, and mating had no significant influence on the occurrence of PMM. Moreover, spiders that underwent PMM lived longer than those that did not and their body sizes were significantly increased. Therefore, we concluded that nutritional condition rather than mating history affect PMM. © 2017. Published by The Company of Biologists Ltd.

The mechanical properties of the non-sticky spiral in Nephila orb webs (Araneae, Nephilidae).

Science.gov (United States)

Hesselberg, Thomas; Vollrath, Fritz

2012-10-01

Detailed information on web geometry and the material properties of the various silks used enables the function of the web's different structures to be elucidated. In this study we investigated the non-sticky spiral in Nephila edulis webs, which in this species is not removed during web building. This permanent non-sticky spiral shows several modifications compared with others, e.g. temporary non-sticky spirals - it is zigzag shaped and wrapped around the radial thread at the elongated junctions. The material properties of the silk used in the non-sticky spiral and other scaffolding structures (i.e. radii, frame and anchor threads) were comparable. However, the fibre diameters differed, with the non-sticky spiral threads being significantly smaller. We used the measured data in a finite element (FE) model of the non-sticky spiral in a segment of the web. The FE analysis suggested that the observed zigzag index resulted from the application of very high pre-stresses to the outer turns of the non-sticky spiral. However, final pre-stress levels in the non-sticky spiral after reorganisation were down to 300 MPa or 1.5-2 times the stress in the radii, which is probably closer to the stress applied by the spider during web building.

Quantification of the physiochemical constraints on the export of spider silk proteins by Salmonella type III secretion

Directory of Open Access Journals (Sweden)

Voigt Christopher A

2010-10-01

Full Text Available Abstract Background The type III secretion system (T3SS is a molecular machine in gram negative bacteria that exports proteins through both membranes to the extracellular environment. It has been previously demonstrated that the T3SS encoded in Salmonella Pathogenicity Island 1 (SPI-1 can be harnessed to export recombinant proteins. Here, we demonstrate the secretion of a variety of unfolded spider silk proteins and use these data to quantify the constraints of this system with respect to the export of recombinant protein. Results To test how the timing and level of protein expression affects secretion, we designed a hybrid promoter that combines an IPTG-inducible system with a natural genetic circuit that controls effector expression in Salmonella (psicA. LacO operators are placed in various locations in the psicA promoter and the optimal induction occurs when a single operator is placed at the +5nt (234-fold and a lower basal level of expression is achieved when a second operator is placed at -63nt to take advantage of DNA looping. Using this tool, we find that the secretion efficiency (protein secreted divided by total expressed is constant as a function of total expressed. We also demonstrate that the secretion flux peaks at 8 hours. We then use whole gene DNA synthesis to construct codon optimized spider silk genes for full-length (3129 amino acids Latrodectus hesperus dragline silk, Bombyx mori cocoon silk, and Nephila clavipes flagelliform silk and PCR is used to create eight truncations of these genes. These proteins are all unfolded polypeptides and they encompass a variety of length, charge, and amino acid compositions. We find those proteins fewer than 550 amino acids reliably secrete and the probability declines significantly after ~700 amino acids. There also is a charge optimum at -2.4, and secretion efficiency declines for very positively or negatively charged proteins. There is no significant correlation with hydrophobicity

Thermal Analysis, Structural Studies and Morphology of Spider Silk-like Block Copolymers

Science.gov (United States)

Huang, Wenwen

Spider silk is a remarkable natural block copolymer, which offers a unique combination of low density, excellent mechanical properties, and thermal stability over a wide range of temperature, along with biocompatibility and biodegrability. The dragline silk of Nephila clavipes, is one of the most well understood and the best characterized spider silk, in which alanine-rich hydrophobic blocks and glycine-rich hydrophilic blocks are linked together generating a functional block copolymer with potential uses in biomedical applications such as guided tissue repair and drug delivery. To provide further insight into the relationships among peptide amino acid sequence, block length, and physical properties, in this thesis, we studied synthetic proteins inspired by the genetic sequences found in spider dragline silks, and used these bioengineered spider silk block copolymers to study thermal, structural and morphological features. To obtain a fuller understanding of the thermal dynamic properties of these novel materials, we use a model to calculate the heat capacity of spider silk block copolymer in the solid or liquid state, below or above the glass transition temperature, respectively. We characterize the thermal phase transitions by temperature modulated differential scanning calorimetry (TMDSC) and thermogravimetric analysis (TGA). We also determined the crystallinity by TMDSC and compared the result with Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). To understand the protein-water interactions with respect to the protein amino acid sequence, we also modeled the specific reversing heat capacity of the protein-water system, Cp(T), based on the vibrational, rotational and translational motions of protein amino acid residues and water molecules. Advanced thermal analysis methods using TMDSC and TGA show two glass transitions were observed in all samples during heating. The low temperature glass transition, Tg(1), is related to

Effects of β-sheet crystals and a glycine-rich matrix on the thermal conductivity of spider dragline silk.

Science.gov (United States)

Park, Jinju; Kim, Duckjong; Lee, Seung-Mo; Choi, Ji-Ung; You, Myungil; So, Hye-Mi; Han, Junkyu; Nah, Junghyo; Seol, Jae Hun

2017-03-01

We measured the thermal conductivity of Araneus ventricosus' spider dragline silk using a suspended microdevice. The thermal conductivity of the silk fiber was approximately 0.4Wm -1 K -1 at room temperature and gradually increased with an increasing temperature in a manner similar to that of other disordered crystals or proteins. In order to elucidate the effect of β-sheet crystals in the silk, thermal denaturation was used to reduce the quantity of the β-sheet crystals. A calculation with an effective medium approximation supported this measurement result showing that the thermal conductivity of β-sheet crystals had an insignificant effect on the thermal conductivity of SDS. Additionally, the enhancement of bonding strength in a glycine-rich matrix by atomic layer deposition did not increase the thermal conductivity. Thus, this study suggests that the disordered part of the glycine-rich matrix prevented the peptide chains from being coaxially extended via the cross-linking covalent bonds. Copyright © 2016 Elsevier B.V. All rights reserved.

Soil organisms associated to the weed suppressant Crotalaria juncea (fabaceae and its importance as a refuge for natural enemies Organismos de solo associados à supressora de plantas daninhas Crotalaria juncea (fabaceae e sua importância como refúgio para inimigos naturais

Directory of Open Access Journals (Sweden)

W.S Tavares

2011-09-01

Full Text Available Soil organisms play an important role in organic crops of Crotalaria juncea (Fabaceae and are associated with the natural conservation of the environment. The present study was aimed to investigate the population of soil organisms in the organic culture of C. juncea, as well as its importance as a refuge for natural enemies. Dalbulus maidis (Hemiptera: Cicadellidae, Diabrotica sp. (Coleoptera: Chrysomelidae, Doru luteipes (Dermaptera: Forficulidae, Gryllus assimilis (Orthoptera: Gryllidae, Lagria villosa (Coleoptera: Lagriidae, Melanotus sp. (Coleoptera: Elateridae, Meloidogyne incognita (Tylenchida: Heteroderidae, Nephila clavipes (Araneae: Nephilidae, Orius insidiosus (Hemiptera: Anthocoridae, Pheidole sp. (Hymenoptera: Myrmicidae, Phyllophaga sp. (Coleoptera: Scarabeidae, Procornitermes sp. (Isoptera: Termitidae, Solenopsis sp. (Hymenoptera: Formicidae, and Utetheisa ornatrix (Lepidoptera: Arctiidae were identified in C. juncea. The organisms that were found during a 3-month period in 144 trenches in C. juncea were pest species (84.47% and natural enemies (15.53% as well. Natural enemies had an average of 11.89 individuals per 1.08 m³ of soil cultivated with C. juncea. The abundance of organisms in the pod stage (5.49% of C. juncea was lower than that in the vegetative (83.50% and flowering (11.01% stages. Crotalaria juncea plants can be used as part of a crop system for Integrated Pest Management.Organismos de solo desempenham um importante papel em cultivos orgânicos de Crotalaria juncea (Fabaceae e estão associados com a conservação natural do ambiente. O presente estudo teve como objetivo investigar a população de organismos de solo no cultivo orgânico de C. juncea, bem como sua importância como um refúgio para inimigos naturais. Dalbulus maidis (Hemiptera: Cicadellidae, Diabrotica sp. (Coleoptera: Chrysomelidae, Doru luteipes (Dermaptera: Forficulidae, Gryllus assimilis (Orthoptera: Gryllidae, Lagria villosa (Coleoptera

Development and fabrication of a dragline training system. Technical progress report, No. 1 (phase 1 final report)

Energy Technology Data Exchange (ETDEWEB)

Voss, William J.

1979-09-17

As a result of the task analysis and revision to the plan of instruction, certain desirable characteristics were recommended to be added to the dragline trainer. These essentially would provide for a high quality feedback and hard copy record of the trainee's performance. It was recommended that the trainer be able to produce and/or sense and record: drag and hoist over-spooling, dragchain/cone contact, bucket shock, bucket stall, lateral boom stress, tight lining, excessive rapid braking and reaction times to internal/external alarms. In addition, data such as cycle time, bucket position, yardage moved and cycles completed should be recorded and records printed. With the exception of drag chain and cone contact indications, these characteristics can be implemented in the computer program. In some cases, such as bucket stall and external alarms it will require instructor initiative to activate specific trainer scenario and reaction time measurements. It should be noted that these additional features, however desirable, add significantly to the required computer capability. Both processor cycle time and memory availability could be restraints. A faster, and larger system could accommodate these added features but at an increase in cost for the computer system. A study is in process and specific recommendations will result.

Natural Occurring Silks and Their Analogues as Materials for Nerve Conduits

Directory of Open Access Journals (Sweden)

Christine Radtke

2016-10-01

Full Text Available Spider silk and its synthetic derivatives have a light weight in combination with good strength and elasticity. Their high cytocompatibility and low immunogenicity make them well suited for biomaterial products such as nerve conduits. Silk proteins slowly degrade enzymatically in vivo, thus allowing for an initial therapeutic effect such as in nerve scaffolding to facilitate endogenous repair processes, and then are removed. Silks are biopolymers naturally produced by many species of arthropods including spiders, caterpillars and mites. The silk fibers are secreted by the labial gland of the larvae of some orders of Holometabola (insects with pupa or the spinnerets of spiders. The majority of studies using silks for biomedical applications use materials from silkworms or spiders, mostly of the genus Nephila clavipes. Silk is one of the most promising biomaterials with effects not only in nerve regeneration, but in a number of regenerative applications. The development of silks for human biomedical applications is of high scientific and clinical interest. Biomaterials in use for biomedical applications have to meet a number of requirements such as biocompatibility and elicitation of no more than a minor inflammatory response, biodegradability in a reasonable time and specific structural properties. Here we present the current status in the field of silk-based conduit development for nerve repair and discuss current advances with regard to potential clinical transfer of an implantable nerve conduit for enhancement of nerve regeneration.

Nuclear Magnetic Resonance (NMR) Spectroscopic Characterization of Nanomaterials and Biopolymers

Science.gov (United States)

Guo, Chengchen

Nanomaterials have attracted considerable attention in recent research due to their wide applications in various fields such as material science, physical science, electrical engineering, and biomedical engineering. Researchers have developed many methods for synthesizing different types of nanostructures and have further applied them in various applications. However, in many cases, a molecular level understanding of nanoparticles and their associated surface chemistry is lacking investigation. Understanding the surface chemistry of nanomaterials is of great significance for obtaining a better understanding of the properties and functions of the nanomaterials. Nuclear magnetic resonance (NMR) spectroscopy can provide a familiar means of looking at the molecular structure of molecules bound to surfaces of nanomaterials as well as a method to determine the size of nanoparticles in solution. Here, a combination of NMR spectroscopic techniques including one- and two-dimensional NMR spectroscopies was used to investigate the surface chemistry and physical properties of some common nanomaterials, including for example, thiol-protected gold nanostructures and biomolecule-capped silica nanoparticles. Silk is a natural protein fiber that features unique properties such as excellent mechanical properties, biocompatibility, and non-linear optical properties. These appealing physical properties originate from the silk structure, and therefore, the structural analysis of silk is of great importance for revealing the mystery of these impressive properties and developing novel silk-based biomaterials as well. Here, solid-state NMR spectroscopy was used to elucidate the secondary structure of silk proteins in N. clavipes spider dragline silk and B. mori silkworm silk. It is found that the Gly-Gly-X (X=Leu, Tyr, Gln) motif in spider dragline silk is not in a beta-sheet or alpha-helix structure and is very likely to be present in a disordered structure with evidence for 31-helix

Radiocesium contamination of the web spider Nephila clavata (Nephilidae: Arachnida) 1.5 years after the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Ayabe, Yoshiko; Kanasashi, Tsutomu; Hijii, Naoki; Takenaka, Chisato

2014-01-01

We measured the concentrations of radiocesium ((134)Cs and (137)Cs) in a large web spider, Nephila clavata L. Koch (Nephilidae: Arachnida), collected at three sites at different distances from the Fukushima Dai-ichi Nuclear Power Plant about 1.5 y after the accident in March 2011. The radiocesium concentrations in spiders were highest in a streamside secondary forest 33 km northwest of the power plant: mean ± a standard deviation of 2.401 ± 1.197 Bq g(-1) dry for (134)Cs and 3.955 ± 1.756 Bq g(-1) dry for (137)Cs. In a hillside secondary forest 37 km northwest of the power plant, the mean concentrations of (134)Cs and (137)Cs were 0.825 ± 0.247 Bq g(-1) dry and 1.470 ± 0.454 Bq g(-1) dry, respectively. In a pine forest 62 km west of the power plant, very low radiocesium concentrations were detected, but in only a few individuals. The concentrations of (134)Cs and (137)Cs in spiders collected at each site tended to be correlated with the air radiation dose rate at each site. Since spiders are key components of food webs in forests, the high concentrations in this species at contaminated sites suggested that the radiocesium from the accident has transferred through food chains and reached to higher trophic level of the food chains. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Relationship between radiocesium contamination and the contents of various elements in the web spider Nephila clavata (Nephilidae: Arachnida)

International Nuclear Information System (INIS)

Ayabe, Yoshiko; Kanasashi, Tsutomu; Hijii, Naoki; Takenaka, Chisato

2015-01-01

The accident at the Fukushima Dai-ichi nuclear power plant seriously contaminated a large area in northeast Japan with a large amount of radioactive material. Consequently, various organisms, including arthropods, in the ecosystem have been contaminated with radiocesium ("1"3"7Cs) through the food chain. We previously showed that the web spider Nephila clavata was contaminated with "1"3"7Cs and that the level of contamination, which varied among spider individuals, was independent of the amount of prey consumed. The present study aimed to clarify the mechanisms that could determine the level of "1"3"7Cs contamination in N. clavata. We first demonstrated the patterns of contents of over 30 elements in N. clavata that were collected at two forest sites (PS and ES) in Fukushima and then focused on the relationships between the contents of the alkali metals Li, Na, K, and Rb and the accumulation of "1"3"7Cs in the spiders; Cs is an alkali metal and is expected to act similarly to Li, Na, K, and Rb. We also focused on the content of the non-alkali element, Cu, which is an essential element for oxygen transport in spiders. We found that Na content correlated positively with "1"3"7Cs accumulation at both sites, which suggested that "1"3"7Cs accumulation in N. clavata was related with the dynamics of Na. The K–, Rb–, and Cu–"1"3"7Cs relationships were site specific; the relationships were significant at site PS, but not significant at site ES. Factors causing the site specific relationships and the probable pathway for "1"3"7Cs transfer from soil to plants and then to higher trophic levels are discussed in terms of the transfer processes of the alkali metals. - Highlights: • Accumulation of "1"3"7Cs and various elements in web spiders was investigated. • "1"3"7Cs accumulation positively correlated with that of K, Rb, Na, and Cu. • Accumulation of alkali metals determined the level of "1"3"7Cs contamination. • K–, Rb–, Cu–"1"3"7Cs relationships were

Structure–Activity Relationship Study of Spider Polyamine Toxins as Inhibitors of Ionotropic Glutamate Receptors

DEFF Research Database (Denmark)

Xiong, Xiaofeng; Poulsen, Mette H; Hussein, Rama A

2014-01-01

The spider polyamine toxins Joro spider toxin-3 (JSTX-3) and Nephila polyamine toxins-1 and -8 (NPTX-1 and NPTX-8) are isolated from the venom of the orb-weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only...

Radiocesium contamination of the web spider Nephila clavata (Nephilidae: Arachnida) 1.5 years after the Fukushima Dai-ichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Ayabe, Yoshiko; Kanasashi, Tsutomu; Hijii, Naoki; Takenaka, Chisato

2014-01-01

We measured the concentrations of radiocesium ( 134 Cs and 137 Cs) in a large web spider, Nephila clavata L. Koch (Nephilidae: Arachnida), collected at three sites at different distances from the Fukushima Dai-ichi Nuclear Power Plant about 1.5 y after the accident in March 2011. The radiocesium concentrations in spiders were highest in a streamside secondary forest 33 km northwest of the power plant: mean ± a standard deviation of 2.401 ± 1.197 Bq g −1 dry for 134 Cs and 3.955 ± 1.756 Bq g −1 dry for 137 Cs. In a hillside secondary forest 37 km northwest of the power plant, the mean concentrations of 134 Cs and 137 Cs were 0.825 ± 0.247 Bq g −1 dry and 1.470 ± 0.454 Bq g −1 dry, respectively. In a pine forest 62 km west of the power plant, very low radiocesium concentrations were detected, but in only a few individuals. The concentrations of 134 Cs and 137 Cs in spiders collected at each site tended to be correlated with the air radiation dose rate at each site. Since spiders are key components of food webs in forests, the high concentrations in this species at contaminated sites suggested that the radiocesium from the accident has transferred through food chains and reached to higher trophic level of the food chains. -- Highlights: • We investigated radiocesium contamination of large web spiders in Fukushima. • Spiders collected at three different sites in Fukushima were contaminated. • Radiocesium concentrations of spiders tended to increase with the air radiation dose rates. • Radiocesium concentrations of spiders did not affect by the amount of prey

Addition to araneofauna of Andhra Pradesh, India: occurrence of three species of Argyrodes Simon, 1864 (Araneae: Theridiidae

Directory of Open Access Journals (Sweden)

S.M.M. Javed

2010-06-01

Full Text Available We report three spider species, namely, Argyrodes nephilae Taczanowski, 1872, A. argentatus O.P.-Cambridge, 1880 and A. flavescens O.P.-Cambridge, 1880 from the family Theridiidae from Andhra Pradesh for the first time. A. nephilae constitutes the first record of this species from India. All the species have been recorded from the webs of Araneidae spiders.

Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore.

Science.gov (United States)

Martins, Carlos H Z; Cunha, Beatriz P; Solferini, Vera N; Trigo, José R

2015-01-01

Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae) sequester N-oxides of pyrrolizidine alkaloids (PAs) from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina), and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves) which is reflected in the adult defense.

Effect of Ecological Restoration on Body Condition of a Predator.

Directory of Open Access Journals (Sweden)

Daniel González-Tokman

Full Text Available Ecological restoration attempts to recover the structure and function of ecosystems that have been degraded by human activities. A crucial test of ecosystem recovery would be to determine whether individuals in restored environments are as healthy as those in conserved environments. However, the impact of restoration on physiology of terrestrial animals has never been tested. Here, we evaluated the effect of two restoration methods on body condition measured as body size, body mass, lipid and muscle content of the spider Nephila clavipes in a tropical dry forest that has suffered chronic disturbance due to cattle grazing. We used experimental plots that had been excluded from disturbance by cattle grazing during eight years. Plots were either planted with native trees (i. e. maximal intervention, or only excluded from disturbance (i. e. minimal intervention, and were compared with control conserved (remnants of original forest and disturbed plots (where cattle is allowed to graze. We predicted (1 better body condition in spiders of conserved and restored sites, compared to disturbed sites, and (2 better body condition in plots with maximal intervention than in plots with minimal intervention. The first prediction was not supported in males or females, and the second prediction was only supported in females: body dry mass was higher in planted than in conserved plots for spiders of both sexes and also higher that in disturbed plots for males, suggesting that plantings are providing more resources. We discuss how different life histories and environmental pressures, such as food availability, parasitism, and competition for resources can explain our contrasting findings in male and female spiders. By studying animal physiology in restoration experiments it is possible to understand the mechanistic basis of ecological and evolutionary processes that determine success of ecological restoration.

A comparative analysis of the morphology and evolution of permanent sperm depletion in spiders.

Directory of Open Access Journals (Sweden)

Peter Michalik

2011-01-01

Full Text Available Once thought to be energetically cheap and easy to produce, empirical work has shown that sperm is a costly and limited resource for males. In some spider species, there is behavioral evidence that sperm are permanently depleted after a single mating. This extreme degree of mating investment appears to co-occur with other reproductive strategies common to spiders, e.g. genital mutilation and sexual cannibalism. Here we corroborate that sperm depletion in the golden orb-web spider Nephila clavipes is permanent by uncovering its mechanistic basis using light and electron microscopy. In addition, we use a phylogeny-based statistical analysis to test the evolutionary relationships between permanent sperm depletion (PSD and other reproductive strategies in spiders. Male testes do not produce sperm during adulthood, which is unusual in spiders. Instead, spermatogenesis is nearly synchronous and ends before the maturation molt. Testis size decreases as males approach their maturation molt and reaches its lowest point after sperm is transferred into the male copulatory organs (pedipalps. As a consequence, the amount of sperm available to males for mating is limited to the sperm contained in the pedipalps, and once it is used, males lose their ability to fertilize eggs. Our data suggest that PSD has evolved independently at least three times within web-building spiders and is significantly correlated with the evolution of other mating strategies that limit males to monogamy, including genital mutilation and sexual cannibalism. We conclude that PSD may be an energy-saving adaptation in species where males are limited to monogamy. This could be particularly important in web-building spiders where extreme sexual size dimorphism results in large, sedentary females and small, searching males who rarely feed as adults and are vulnerable to starvation. Future work will explore possible energetic benefits and the evolutionary lability of PSD relative to other

Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore.

Directory of Open Access Journals (Sweden)

Carlos H Z Martins

Full Text Available Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae sequester N-oxides of pyrrolizidine alkaloids (PAs from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina, and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves which is reflected in the adult defense.

Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells

Science.gov (United States)

Lazaris, Anthoula; Arcidiacono, Steven; Huang, Yue; Zhou, Jiang-Feng; Duguay, François; Chretien, Nathalie; Welsh, Elizabeth A.; Soares, Jason W.; Karatzas, Costas N.

2002-01-01

Spider silks are protein-based ``biopolymer'' filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to ``biomimic'' the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

More than a safety line: jump-stabilizing silk of salticids.

Science.gov (United States)

Chen, Yung-Kang; Liao, Chen-Pan; Tsai, Feng-Yueh; Chi, Kai-Jung

2013-10-06

Salticids are diurnal hunters known for acute vision, remarkable predatory strategies and jumping ability. Like other jumpers, they strive for stability and smooth landings. Instead of using inertia from swinging appendages or aerodynamic forces by flapping wings as in other organisms, we show that salticids use a different mechanism for in-air stability by using dragline silk, which was previously believed to function solely as a safety line. Analyses from high-speed images of jumps by the salticid Hasarius adansoni demonstrate that despite being subject to rearward pitch at take-off, spiders with dragline silk can change body orientation in the air. Instantaneous drag and silk forces calculated from kinematic data further suggest a comparable contribution to deceleration and energy dissipation, and reveal that adjustments by the spider to the silk force can reverse its body pitch for a predictable and optimal landing. Without silk, upright-landing spiders would slip or even tumble, deferring completion of landing. Thus, for salticids, dragline silk is critical for dynamic stability and prey-capture efficiency. The dynamic functioning of dragline silk revealed in this study can advance the understanding of silk's physiological control over material properties and its significance to spider ecology and evolution, and also provide inspiration for future manoeuvrable robot designs.

Strip mining with hydraulic shover and cross-pit stacker; Tagebau mit hydraulischen Hochloeffelbagger und Direktversturz-Absetzer

Energy Technology Data Exchange (ETDEWEB)

Streck, W. [Dipl.-Ing. Willibald Streck, Boden, Wasser, Rohstoff, Bruehl (Germany)

2005-09-01

In the standard strip mining of sedimentary deposits draglines are used for overburden removal. In this paper an alternative is presented which offers significantly lower initial investment costs and equal operating and maintenance costs. It is applicable in certain mining conditions. The stripping system consists of a standard hydraulic shovel excavator loading into a hopper/stacker on crawlers (XPS). With a shovel of 34 m{sup 3} size the stripping height is limited to approximately 15 to 17 m. Cuts of 15 to 20 m width may be worked. The XPS may have a hopper size of 70 m{sup 3} and a discharge boom of 70 m. The system reaches an annual capacity in the range of 12 mill bank m{sup 3}. It compares well with a standard dragline of the Bucyrus W 2000 type. While the operating and maintenance cost per bank m{sup 3} are about the same, the initial investment costs differ drastically, about 16 mill US-Dollar for the shovel/XPS compared to 24 mill US-Dollar for the dragline. In new surface mining projects and under distinct mining conditions the low investment costs and other advantages may balance the limitations of the shovel/XPS system and justify the deviation from the standard stripping dragline. (orig.)

Uncovering the structure-function relationship in spider silk

Science.gov (United States)

Yarger, Jeffery L.; Cherry, Brian R.; van der Vaart, Arjan

2018-03-01

All spiders produce protein-based biopolymer fibres that we call silk. The most studied of these silks is spider dragline silk, which is very tough and relatively abundant compared with other types of spider silks. Considerable research has been devoted to understanding the relationship between the molecular structure and mechanical properties of spider dragline silks. In this Review, we overview experimental and computational studies that have provided a wealth of detail at the molecular level on the highly conserved repetitive core and terminal regions of spider dragline silk. We also discuss the role of the nanocrystalline β-sheets and amorphous regions in determining the properties of spider silk fibres, endowing them with strength and elasticity. Additionally, we outline imaging techniques and modelling studies that elucidate the importance of the hierarchical structure of silk fibres at the molecular level. These insights into structure-function relationships can guide the reverse engineering of spider silk to enable the production of superior synthetic fibres.

Concentration and behavior of radioactive cesium in several kinds of mushrooms in Hokkaido, (2)

International Nuclear Information System (INIS)

Okui, Toyo; Kobayashi, Satoshi; Takizawa, Namio.

1991-01-01

Concentrations of 137 Cs, 134 Cs and potassium were measured in cultivated and wild mushrooms and their matrixes (soils or woods) collected from Hokkaido in 1990. The 137 Cs concentrations in mushrooms were in the range of 0.07-188.9Bq/kg fresh weight. The highest 137 Cs concentration was observed in Clitocybe clavipes. The 137 Cs concentration ratios of the wood rotting fungi and the actomycorrhizal fungi were 0.8-5.0 and 0.3-1.1, respectively. Both values of mushrooms were remarkably higher than that of leafvegetables (10 -2 ∼10 -3 ). The potassium concentrations in mushrooms were in the range of 0.08-0.63 %. 134 Cs released from the Chernobyl atomic power plant stationin 1986 was observed in only Clitocybe clavipes. (author)

Application of a cross-pit bridge conveyor system in mining

Energy Technology Data Exchange (ETDEWEB)

Zeindler, R.W. (Krupp Canada Inc., Calgary, Alberta); Fawcett, D.A.

1981-04-01

A summary is presented of the report completed by the Coal Mining Research Centre in 1980. This report was of a cross-pit conveyor system applied as an auxillary mining complement to the major stripping unit, a dragline. The purpose of the CMRC report was to evaluate selective mining and replacement of the upper horizons of the strata as an aid in reclamation. These strata were the topsoil, subsoil and glacial till. Past utilization of cross-pit conveyor systems and related engineering studies were assessed. The parameters of the study were based on the mining and geological conditions of the Alberta prairie coal mines. The principal excavator for stripping was a dragline. Excavation of the upper horizons was done by a bucket-wheel excavator discharging onto the cross-pit conveyor. Alternative equipment applications were economically compared. Four cases or geological sections were evaluated in detail. The economics of the alternative mining systems for each of the cases were determined. In all instances, the most economical solution was a tandem system utilizing a dragline with a bucket-wheel excavator/cross-pit conveyor system. For both the CMRC study and a similar US paper, the application of a tandem system provided the lowest annual ownership and operating costs. The tandem system consists of a dragline excavating and casting the majority of the waste or overburden and a BWE/CPCS selectively excavating and replacing the topsoil, subsoil and part of the unconsolidated overburden. The bridge spans and designs are within known technical and economic limits.

Spider Silk Violin Strings with a Unique Packing Structure Generate a Soft and Profound Timbre

Science.gov (United States)

Osaki, Shigeyoshi

2012-04-01

We overcome the difficulties in pulling long draglines from spiders, twist bundles of dragline filaments, and succeed in preparing violin strings. The twisting is found to change the cross section shapes of filaments from circular to polygonal and to optimize the packing structure with no openings among filaments providing mechanically strong and elastic strings. The spider string signal peaks of overtones for the violin are relatively large at high frequencies, generating a soft and profound timbre. Such a preferable timbre is considered to be due to the unique polygonal packing structure which provides valuable knowledge for developing new types of materials.

Monster machines

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-01-15

The mining industry is renowned for its gigantic pieces of machinery and they do not come much bigger than the three pieces being examined in this paper. Most bucketwheel excavators delivered now are in the 1000-4500 m{sup 3}/h capacity range. Bucyras Inc. is responsible for the world's largest dragline, the Big Muskie, claimed to be one of the seven engineering wonders of the world. However, emphasis today is on smaller draglines such as the Bucyrus 680 W. Manufacturers of surface miners include Man Takraf, ThyssenKrupp Foerdertechnik, Wirtgen and the Huron Manufacturing Corp. 2 photos.

Second-order nonlinear optical microscopy of spider silk

Science.gov (United States)

Zhao, Yue; Hien, Khuat Thi Thu; Mizutani, Goro; Rutt, Harvey N.

2017-06-01

Asymmetric β-sheet protein structures in spider silk should induce nonlinear optical interaction such as second harmonic generation (SHG) which is experimentally observed for a radial line and dragline spider silk using an imaging femtosecond laser SHG microscope. By comparing different spider silks, we found that the SHG signal correlates with the existence of the protein β-sheets. Measurements of the polarization dependence of SHG from the dragline indicated that the β-sheet has a nonlinear response depending on the direction of the incident electric field. We propose a model of what orientation the β-sheet takes in spider silk.

New record for the invasive Spotted Wing Drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae) in Anillaco, Argentina

Science.gov (United States)

The invasive Spotted Wing Drosophila (SWD), Drosophila suzukii Matsumura, is reported for the first time in La Rioja, Argentina. This represents a major range expansion for this species. The natural enemies of SWD, Leptopilina clavipes and Ganaspis hookeri were also collected with the SWD at the s...

Mining on the Mesa

Energy Technology Data Exchange (ETDEWEB)

Sprouls, M.W.

1994-10-01

Peabody Western Coal Co. is the owner of Black Mesa and Kayenta coal opencast mines, both sited on Hopi and Navajo lands. 93% of the employees are native American, mostly Navajo. Kayenta is the larger and extracts coal with draglines. Sulphur content is high so the coal has to be analyzed and carefully blended before use. Black Mesa also uses draglines, here quality control is not as important as it is at Kayenta. Coal is transported to power stations using slurry pipelines. Both mines are heavily involved in land reclamation, leaving a landscape that makes better grazing than it did before mining. 2 figs.

Determination Of Longevity Of Teeth In Buckets Of Loading Equipment In Coal Mines - A Case Study

Directory of Open Access Journals (Sweden)

Aarif Jamal

2015-08-01

Full Text Available The life of bucket teeth in shovel and dragline deployed in handling of overburden rock is an important contributor to the stores cost and is also responsible for the loss of valuable availability and utilisation time of these critical equipment. To ascertain the effect of rock type on longevity of bucket teeth a study has been conducted in two large opencast mines of Singrauli Coalfields. The results of this study is presented in this paper. There was a significant variation as compared to the actual figures of the mine it establish useful relationship between the type of mineral present in the overburden and the life of bucket teeth of shovel and dragline.

Transgenic Silk Moths to Produce Spider Silk

National Research Council Canada - National Science Library

Herrera, Rene J

2008-01-01

.... Other alternatives like production of the protein that yields same or similar mechanical properties of dragline silk in microorganisms or mammalian cells, in spinning fibers from concentrated protein...

Bioprospecting finds the toughest biological material: extraordinary silk from a giant riverine orb spider.

Directory of Open Access Journals (Sweden)

Ingi Agnarsson

Full Text Available BACKGROUND: Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41,000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200,000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila or simply from researchers' backyards. Are we limited to 'blindly fishing' in efforts to discover extraordinary silks? Or, could scientists use ecology to predict which species are likely to spin silks exhibiting exceptional performance properties? METHODOLOGY: We examined the biomechanical properties of silk produced by the remarkable Malagasy 'Darwin's bark spider' (Caerostris darwini, which we predicted would produce exceptional silk based upon its amazing web. The spider constructs its giant orb web (up to 2.8 m(2 suspended above streams, rivers, and lakes. It attaches the web to substrates on each riverbank by anchor threads as long as 25 meters. Dragline silk from both Caerostris webs and forcibly pulled silk, exhibits an extraordinary combination of high tensile strength and elasticity previously unknown for spider silk. The toughness of forcibly silked fibers averages 350 MJ/m(3, with some samples reaching 520 MJ/m(3. Thus, C. darwini silk is more than twice tougher than any previously described silk, and over 10 times better than Kevlar®. Caerostris capture spiral silk is similarly exceptionally tough. CONCLUSIONS: Caerostris darwini produces the toughest known biomaterial. We hypothesize that this extraordinary toughness coevolved with the unusual ecology and web architecture of these spiders, decreasing the likelihood of bridgelines breaking and collapsing the web

Structure, composition and mechanical properties of the silk fibres of ...

Indian Academy of Sciences (India)

The silk egg case and orb web of spiders are elaborate structures that are assembled from a number of components. We analysed the structure, the amino acid and fibre compositions, and the tensile properties of the silk fibres of the egg case of Nephila clavata. SEM shows that the outer and inner covers of the egg case ...

Phononic band gap and mechanical anisotropy in spider silk

Science.gov (United States)

Papadopoulos, Periklis; Gomopoulos, Nikos; Kremer, Friedrich; Fytas, George

2010-03-01

Spider dragline silk is a semi-crystalline biopolymer exhibiting superior properties compared to synthetic polymers with similar chemical structure, such as polyamides. This is ascribed to the hierarchical nanostructure that is created in the spinning duct. During this process the aqueous solution of the two protein constituents of dragline silk is crystallized, while the macromolecules maintain their high orientation, leading to a high value of the Young's modulus (in the order of 10 GPa) along the fiber. We employed spontaneous Brillouin light scattering to measure the longitudinal modulus (M//,,M) along the two symmetry directions of the native fiber with increased (decreased) pre-strain created by stretching (supercontracting after hydration). A strong mechanical anisotropy is found; at about 18% strain M///M˜5. Most important, an unexpected finding is the first observation of a unidirectional hypersonic phononic band gap in biological structures. This relates to the existence of a strain-dependent correlation length of the mechanical modulus in the submicron range along the fiber axis.

Spider-silk-like shape memory polymer fiber for vibration damping

International Nuclear Information System (INIS)

Yang, Qianxi; Li, Guoqiang

2014-01-01

In this study, the static and dynamic properties of shape memory polyurethane (SMPU) fiber are reported and compared to those of spider dragline silk. Although the polymeric fiber has a lower strength compared to spider dragline silks (0.2–0.3 GPa versus 1.1 GPa), it possesses much higher toughness (276–289 MJ m −3 versus 160 MJ m −3 ), due to its excellent extensibility. The dynamic mechanical tests reveal that SMPU fiber has a high damping capacity (tan δ = 0.10–0.35) which is comparable to or even higher than that of spider silks (tan δ = 0.15). In addition, we found that, different programming methods change the shape memory and damping properties of the fiber in different ways and cold-drawing programming is more advocated in structural applications. These results suggest that the SMPU fiber has similar vibration damping and mechanical properties as spider silk, and may find applications in lightweight engineering structures. (paper)

78 FR 52967 - Notice of Intent To Initiate Public Scoping and Prepare an Environmental Impact Statement for...

Science.gov (United States)

2013-08-27

..., the overburden (sedimentary rock material covering the coal seams) would be drilled and blasted... pass. After the dragline exposes the coal seam in each pass, the coal would be drilled and blasted. A...) Sediment control, (2) soil salvage, (3) access and haul roads, (4) blasting, (5) overburden removal, (6...

Another punch in the wall (Part 2)

Energy Technology Data Exchange (ETDEWEB)

Przhedetsky, B. [Rock Ignition Pty Ltd. (Australia)

2009-09-15

Based on feedback from readers to the story of coal mining extraction techniques in the July-August 2009 edition of this journal the overview is continued and more detail is given on certain methods and equipment used. Section headings are: draglines; bucket wheel excavators; truck and shovel; overburden slusher; and underground gasification.

Experience of the leading miner crew in the 'Severo-Vostochnyi' im. 50-letiya Velikogo Oktyabrya surface mine. Opyt raboty peredovykh brigad razreza 'Severo-vostochnyi' im. 50-letiya Velikogo Oktyabrya

Energy Technology Data Exchange (ETDEWEB)

Banshchikov, G I; Demidova, A O

1981-01-01

The paper evaluates surface coal mining in the Dal'vostugol' association. Five surface mines of the association mined 13.8 Mt in 1980, 105,900 m/sup 3/ of overburden were removed, overburden to coal ratio was 7.67 m/sup 3//t, labor productivity per miner was 663 t/month, mining cost 2.70 ruble/t. Use of powerful walking draglines for mining, overburden removal and spoil bank formation influenced mining schemes and permitted labor productivity to be increased. Mining schemes without transport of overburden are shown . The following types of mining equipment were used: EhSh-15/90, EhSh-14/75, EhSh-10/60 and EhSh-10/70 draglines, EhKG-4.6u and EhVG-4I face shovels. Mining and geologic conditions are described: climatic conditions are characterized by intensive temperature fluctuation. Air temperature in January ranges from minus 26.8 C to minus 41.0 C and in July from 7.2 C to 31.9 C, the annual precipitation is 622 mm. Thickness of frozen soil in winter ranges from 2.5 to 3.0 m. Geologic conditions of the basin are analyzed: coal seam thickness, depth, coal properties, ash, sulfur, volatile matter, moisture, calorific value, stratification of overburden, mechanical properties of overburden, ground water and water influx. Operation of the Dal'vostugol' mines is described on the example of the Severo-Vostochnyi surface mine, the largest of the region (47% of the coal output). The following aspects of mine operation are evaluated: coal output, economic analysis, mining cost, mining equipment, earthmoving equipment (draglines), mine haulage, effects of climates (particularly equipment repairs), mining schemes, failures of excavators, innovation and safety.

Structural studies on proton/protonation of the protein molecule

International Nuclear Information System (INIS)

Morimoto, Yukio; Kida, Akiko; Chatake, Toshiyuki; Yamaguchi, Hiroshi; Hosokawa, Keiichi; Murakami, Takuto; Umino, Masaaki; Tanaka, Ichiro; Hisatome, Ichiro; Yanagisawa, Yasutake; Fujiwara, Satoshi; Hidaka, Yuji; Shimamoto, Shigeru; Fujiwara, Mitsutoshi; Nakanishi, Takeyoshi

2015-01-01

This paper reports three studies involved in the analysis of protons and protonation at physiologically active sites in protein molecules. (1) 'Elucidation of the higher-order structure formation and activity performing mechanism of yeast proteasome.' With an aim to apply to anti-cancer drugs, this study performed the shape analysis of the total structure of 26S proteasome using small-angle X-ray scattering to clarify the complex form where controlling elements bonded to the both ends of 20S catalyst body, and analyzed the complex structure between the active sites of 20S and inhibitor (drug). (2) 'Basic study on the neutron experiment of biomolecules such as physiologically active substances derived from Natto-bacteria.' This study conducted the purification, crystallization, and X-ray analysis experiment of nattokinase; high-grade purification and solution experiment of vitamin K2 (menaquinone-7); and Z-DNA crystal structure study related to the neutron crystal analysis of DNA as another biomolecule structure study. (3) 'Functional evaluation on digestive enzymes derived from Nephila clavata.' As an Alzheimer's disease-related amyloid fibril formation model, this study carried out elucidation on the fibrosis and fiber-forming mechanism of the traction fiber of Nephila clavata, and the functional analysis of its degrading enzyme. (A.O.)

Ballooning behavior in the golden orbweb spider Nephilapilipes (Araneae: Nephilidae

Directory of Open Access Journals (Sweden)

Vanessa M.J. Lee

2015-01-01

Full Text Available Ballooning, a mode of aerial dispersal in spiders, is an innate behavior that requires appropriate physiological and meteorological conditions. Although only rarely reported in the golden orbweb spiders, family Nephilidae, the large geographic distributions of most nephilids—in particular of Nephila species—would imply that these spiders likely routinely disperse by ballooning in spite of giant female sizes. Here we study ballooning behavior in the golden orbweb spider Nephila pilipes (Fabricius, 1793. Specifically, we test for the propensity of spiderlings to deploy ballooning as a dispersal mechanism. We subjected a total of 59 first-instar spiderlings to a wind experiment at two wind speeds (2.17 ± 0.02 m s-1 and 3.17 ± 0.02 m s-1 under laboratory conditions. Under an average wind speed of 3.17 m s-1, none of the spiderlings exhibited pre-ballooning or ballooning behavior. However, at an average wind speed of 2.17 m s-1, 53 (89.8% spiderlings showed pre-ballooning behavior, and 17 (32.1% of the pre-ballooners ultimately ballooned. Our results concur with prior reports on spiderlings of other families that pre-ballooning behavior is a requirement for ballooning to occur. Furthermore, although we cannot rule out other dispersal mechanisms such as synanthropic spread, our findings suggest that the widespread N. pilipes uses ballooning to colonize remote oceanic islands.

Making ropes work

Energy Technology Data Exchange (ETDEWEB)

Gower, E. [WRCA (United States)

2006-11-15

The article looks at types of rope for different applications of surface mining ropes. The Wire Rope Corp. of America (WRCA), a leading producer, has over the last three years introduced shovel hoist rope, a new line of dragline ropes and a new drag rope designed for reverse bend fairlead systems. Each of these is discussed in the short article, with results from actual field use.

Failures of chain systems

CSIR Research Space (South Africa)

James, A

1997-03-01

Full Text Available ?C and intermittent exposure at 400--450 ?C. Unlike structural steels, which become softer and more ductile when reheated in service, manga- nese steels become brittle when reheated sufficiently to induce carbide... to form a roughly oval shaped crack until the link section could no longer withstand the applied loading experienced during normal dragline operations, and this resulted in final fast brittle failure. The general...

Definition of rehabilitation strategies for pre-strip tertiary spoil at coal mines in central Queensland

International Nuclear Information System (INIS)

Bell, L.C.; Mulligan, D.R.; Mitchell, R.J.; Philp, M.W.; Roe, P.A.

1994-01-01

In the open-cut coal mines of central Queensland, the conventional dragline removal of overburden results in a spoil surface dominated by Permian sediments. In recent years, however, a number of mines have changed their coal exposure methods to include a pre-stripping operation to create a bench for the dragline up to 50 m below the surface. This approach has allowed economic coal recovery from greater depths, but, since this pre-strip material is being deposited on existing spoil piles, it has resulted in a major change in the type of spoil material on the surface. The aims of this project were, firstly, to define the characteristics of this pre-strip material that could cause problems for the establishment and growth of both introduced pasture grasses and native tree species, and secondly, to explore possible spoil amendments which could ameliorate some or all of these limitations. Analyses on the range of spoils included pH, EC and sodicity. Straw mulch also reduced the crust strength and was an effective means of improving vegetative establishment. A complementary field trial was established at Saraji mine in April 1991, and after 4 months, treatments which involved a 30 cm capping of soil on the spoil resulted in the highest densities of tree seedling

One-shot genitalia are not an evolutionary dead end - Regained male polygamy in a sperm limited spider species

Directory of Open Access Journals (Sweden)

Michalik Peter

2011-07-01

Full Text Available Abstract Background Monogynous mating systems with extremely low male mating rates have several independent evolutionary origins and are associated with drastic adaptations involving self-sacrifice, one-shot genitalia, genital damage, and termination of spermatogenesis immediately after maturation. The combination of such extreme traits likely restricts evolutionary potential perhaps up to the point of making low male mating rates irreversible and hence may constitute an evolutionary dead end. Here, we explore the case of a reversion to multiple mating from monogynous ancestry in golden orb-web spiders, Nephila senegalensis. Results Male multiple mating is regained by the loss of genital damage and sexual cannibalism but spermatogenesis is terminated with maturation, restricting males to a single loading of their secondary mating organs and a fixed supply of sperm. However, males re-use their mating organs and by experimentally mating males to many females, we show that the sperm supply is divided between copulations without reloading the pedipalps. Conclusion By portioning their precious sperm supply, males achieve an average mating rate of four females which effectively doubles the maximal mating rate of their ancestors. A heritage of one-shot genitalia does not completely restrict the potential to increase mating rates in Nephila although an upper limit is defined by the available sperm load. Future studies should now investigate how males use this potential in the field and identify selection pressures responsible for a reversal from monogynous to polygynous mating strategies.

Management information systems in NCL - a pragmatic approach

Energy Technology Data Exchange (ETDEWEB)

Mittal, R.L.; Singh, M.K. [Northern Coalfields Limited, Sidhi (India)

2000-05-01

An information system named 'Information Retrieval System' (IRS) has been developed by Northern Coalfields Ltd., India, as a management information system for monitoring use of shovels, dumpers, draglines, diesel, lubricants, power, explosives and overtime expenditure. Reports are generated at regular intervals on production and consumption (if diesel, lubricant, power, explosives, overtime) and used to gauge overall performance of the coal mining operations. The present system is in Lotus 123 worksheefs. 2 apps.

Dicty_cDB: Contig-U11784-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available Y844113_1( AY844113 |pid:none) Hypsiboas sp. CWM 19512 tyrosinase... 40 0.19 EF364207_1( EF364207 |pid:none)...re... 40 0.24 AY844112_1( AY844112 |pid:none) Hypsiboas nympha tyrosinase precur... 40 0.24 AY844148_1( AY84... Natalobatrachus bonebergi isolate ... 40 0.24 AY844081_1( AY844081 |pid:none) Hypsiboas...ensis tyrosine... 39 0.41 AY844110_1( AY844110 |pid:none) Hypsiboas sibleszi tyrosinase prec... 39 0.41 DQ28...aradrahyla nephila tyrosinase pr... 39 0.41 AY844057_1( AY844057 |pid:none) Hypsiboas

Upper lethal temperatures in three cold-tolerant insects are higher in winter than in summer.

Science.gov (United States)

Vu, Henry M; Duman, John G

2017-08-01

Upper lethal temperatures (ULTs) of cold-adapted insect species in winter have not been previously examined. We anticipated that as the lower lethal temperatures (LLTs) decreased (by 20-30°C) with the onset of winter, the ULTs would also decrease accordingly. Consequently, given the recent increases in winter freeze-thaw cycles and warmer winters due to climate change, it became of interest to determine whether ambient temperatures during thaws were approaching ULTs during the cold seasons. However, beetle Dendroides canadensis (Coleoptera: Pyrochroidae) larvae had higher 24 and 48 h ULT 50 (the temperature at which 50% mortality occurred) in winter than in summer. The 24 and 48 h ULT 50 for D. canadensis in winter were 40.9 and 38.7°C, respectively. For D. canadensis in summer, the 24 and 48 h ULT 50 were 36.7 and 36.4°C. During the transition periods of spring and autumn, the 24 h ULT 50 was 37.3 and 38.5°C, respectively. While D. canadensis in winter had a 24 h LT 50 range between LLT and ULT of 64°C, the summer range was only 41°C. Additionally, larvae of the beetle Cucujus clavipes clavipes (Coleoptera: Cucujidae) and the cranefly Tipula trivittata (Diptera: Tipulidae) also had higher ULTs in winter than in summer. This unexpected phenomenon of increased temperature survivorship at both lower and higher temperatures in the winter compared with that in the summer has not been previously documented. With the decreased high temperature tolerance as the season progresses from winter to summer, it was observed that environmental temperatures are closest to upper lethal temperatures in spring. © 2017. Published by The Company of Biologists Ltd.

Hail creek

Energy Technology Data Exchange (ETDEWEB)

Chadwick, J.

2005-09-01

The paper examines the development of one of the largest coking coal deposits in the world. Hail Creek is 100 km west of Mackay and 35 km northeast of Nebo, Queensland and has proven opencut reserves of 195.6 as at December 2003. Coal processing stated in July 2003. The award winning project included construction of a coal handling and preparation plant, a railway, a village and offsite infrastructure and mine buildings and site services. Coal is mined by conventional dragline and truck/shovel techniques. 1 photo.

Development of opencast mining technology during the last decade. El desarrollo de la tecnologia de la mineria de superficie de la ultima decada

Energy Technology Data Exchange (ETDEWEB)

Van Leyen, H. (Rheinbraun Engineering und Wasser GmbH, Koeln (Germany). Departamento de Ingernieria Mecancia)

1992-03-01

This review only covers the development of equipment and technology and is limited to those projects involving bucket wheel excavators, including compact conveyors for use with bucket wheel excavators, main and intermediate conveyors, overburden stripping systems for continuous mining operations, cutting and trenching equipment, crushing and conveying systems for hard rock mining, aspects of excavator and dumper systems, surface winning machines, draglines and special developments in the field of materials handling and storage, blasting and other deep-mining operations. 24 refs., 19 figs., 1 tab.

Giant Syncrude oilsand plant a prodigious user of propane

International Nuclear Information System (INIS)

Anon

2001-01-01

Approximately 13 per cent of Canada's petroleum requirements are met by the huge Syncrude plant in northern Alberta, the largest producer of crude from oilsands in the world and the largest source producer in Canada. The plant is located just north of Fort McMurray northeast of Edmonton. The operation of the plant relies in a very large part on the use of propane. Scattered on the site are 130 propane tanks. The pumphouse is equipped with four 1,000-gallon tanks, and the mobile Sundog heaters in the mine site are equipped with a number of 420-pound tanks that supply the required power. The yearly maintenance program requires the use of an additional 80 to 90 tanks that are brought on the site for that purpose. All told, two million litres of propane are used yearly at the plant. Heating the facilities and equipment is the main use for the propane. For example, heating the draglines (25-storey high and a bucket as large as a two-car garage) that scoop the oilsand and transport it for processing necessitate the use of several 20-pound and 40-pound propane-powered tiger torches. However, large trucks and shovels, part of an innovative transport system called hydro transport, will soon replace the draglines. This new method eliminates the need for draglines, bucket wheels, conveyer systems and conditioning tumblers by mixing the oilsand with water for transportation by pipeline. The first step of the extraction process, the conditioning, occurs in the pipeline. Upon reaching the extraction plant, the mixture is directed into the separation vessels. Without an increase in energy usage or carbon dioxide emissions, Syncrude is able to increase its extraction activity by switching to hydro transport. The requirement for propane is still present as the bottom of the slurry has to be heated for transport. Some basic facts concerning Syncrude and its operation were presented, as well as an overview of the oilsand business, its history and its financial results. For example

Recombinant DNA production of spider silk proteins.

Science.gov (United States)

Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L

2013-11-01

Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce recombinant spider silks. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Old shovels with digital control technology retrofits give new units a run for their money

Energy Technology Data Exchange (ETDEWEB)

Duskey, M.R. [Avtron Manufacturing Inc., Cleveland, OH (United States)

2006-04-15

New digital drive control systems can be retrofitted to shovels and draglines to maximize their performance and keep them running smoothly and reliably. Case histories of successful retrofits are reported. The static drives on a Marion 310 DC drive shovel operating in British Columbia were replaced with Avtron Firing Modules to improve machine availability. Three old Bucyrus 295 M-G set-controlled shovels operated by mines in North Dakota and Labrador which were experiencing excessive downtime were replaced with an Avtron ADD-32DMG field regulator. 2 figs.

Excavating wide inclines in weak strata

Energy Technology Data Exchange (ETDEWEB)

Kuznetsov, N N [Ukrspetsstroiproekt (USSR)

1990-09-01

Discusses schemes for excavation of transport inclines in surface mines under conditions of weak, unstable rocks characterized by a high water content. The schemes are aimed at maximum reduction of excavation operations without infringing the safety of personnel. Use of walking draglines (the EhSh-20/90, EhSh-100/100 and EhSh-10/70) is evaluated. Optimum schemes for incline excavation and determining optimum slope inclination are described on the example of the Berezovsk brown coal surface mine in the USSR. Efficiency of optimum schemes is analyzed: range of excavation, safety degree, landslide hazards, water influx rate, accident rate, etc.

Atomistic model of the spider silk nanostructure

Science.gov (United States)

Keten, Sinan; Buehler, Markus J.

2010-04-01

Spider silk is an ultrastrong and extensible self-assembling biopolymer that outperforms the mechanical characteristics of many synthetic materials including steel. Here we report atomic-level structures that represent aggregates of MaSp1 proteins from the N. Clavipes silk sequence based on a bottom-up computational approach using replica exchange molecular dynamics. We discover that poly-alanine regions predominantly form distinct and orderly beta-sheet crystal domains while disorderly structures are formed by poly-glycine repeats, resembling 31-helices. These could be the molecular source of the large semicrystalline fraction observed in silks, and also form the basis of the so-called "prestretched" molecular configuration. Our structures are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content.

A device for selecting the slack in underground cable for dragline excavators

Energy Technology Data Exchange (ETDEWEB)

Vul, Yu Ya; Koshkarev, A V; Mamkin, V M; Maslov, I G; Sapilov, A V; Simonov, Yu V; Ushakov, L I

1982-01-01

The patented device includes a controllable converter for the lift drive, a command apparatus, a lift drive tension regulator, a sensor of force in the lift cables and the product of this force, the speeds of the drives of the lift and the link, a force assigner and a force regulator in the lift cables and keying elements. To reduce the dynamic loads in the elastic elements of the lift mechanism and the arm, the device is equipped with a regulator for the random force in the lift cable, a sensor of the random speed of the lift drive, six keying elements with a resistor, shunted by a first keying element and switched in to the input of the second keying element and to the output of the regulator of the random force in the lift cables, to the input of which the sensor of the force in the lift cables is switched in through the sensor of the product of this force and the output of the force regulator, to the inputs of which the outputs of the command apparatus are switched in through the parallelly switched third and fourth keying elements and the output of the force sensor directly.

Life history trade-offs imposed by dragline use in two money spiders

OpenAIRE

Bonte, Dries; Verduyn, Lieselot; Braeckman, Bart

2016-01-01

Trade-offs among life history traits are central to understanding the limits of adaptations to stress. In animals, virtually all decisions taken during life are expected to have downstream consequences. To what degree rare, but energy-demanding, decisions carry over to individual performance is rarely studied in arthropods. We used spiders as a model system to test how single investments in silk use - for dispersal or predator escape - affect individual performance. Silk produced for safe lin...

Optically probing torsional superelasticity in spider silks

Energy Technology Data Exchange (ETDEWEB)

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

2013-11-11

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

Optically probing torsional superelasticity in spider silks

International Nuclear Information System (INIS)

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

2013-01-01

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10 2−3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices

The genetic basis of male fertility in relation to haplodiploid reproduction in Leptopilina clavipes (Hymenoptera : Figitidae)

NARCIS (Netherlands)

Pannebakker, BA; Beukeboom, LW; van Alphen, JJM; Brakefield, PM; Zwaan, BJ

Traits under relaxed selection are expected to become reduced or disappear completely, a process called vestigialization. In parthenogenetic populations, traits historically involved in sexual reproduction are no longer under selection and potentially subject to such reduction. In Leptopilina

Abelhas sem ferrão (Hymenoptera: Apidae, Meliponini da Estação Ecológica de Água Limpa, Cataguases-MG, Brasil.

Directory of Open Access Journals (Sweden)

Hugo Werneck

2014-08-01

Stingless Bees of the Estação Ecológica de Água Limpa, Cataguases-MG, Brazil Abstract. This study carried out a survey of nests of stingless bees present in the Estação Ecológica de Água Limpa (EEAL in the municipality of Cataguases, Minas Gerais. We found twenty-one nests belonging to nine species: Friesella schrottkyi (Friese, Melipona bicolor Lepeletier, Plebeia sp. 1, Plebeia sp. 2, Tetragona clavipes (Fabricius, Tetragona quadrangula (Fabricius, Tetragonisca angustula (Latreille, Trigona hyalinata (Lepeletier, Trigona spinipes (Fabricius. Twenty of the 21 nests were found in arboreal substrate. The fauna of stingless bees observed in EEAL is represented by a low number of species. Although the local vegetation has the potential to provide substrates for nesting and floral resources, the low species richness may be related to the fact that the EEAL is an isolated forest remnant.

Manejo y evaluación de ectomicorrizas en especies forestales

Directory of Open Access Journals (Sweden)

A. Carrera-Nieva

2004-01-01

Full Text Available Con el propósito de establecer la capacidad simbiótica de hongos ectomicorrízicos con Pinus patula y Pinus greggii en este trabajo se evaluaron ocho hongos ectomicorrízicos, los cuales se seleccionaron debido a su amplia distribución y comestibilidad. Los porcentajes de colonización micorrízica variaron entre especies de 9 a 66 %. Las plantas inoculadas con Laccaria laccata y Suillus pseudobrevipes presentaron un mayor porcentaje de colonización y desarrollaron un micelio externo abundante. Los valores medios más altos en altura, peso seco y diámetro del tallo se observaron en plantas inoculadas con Lacaria laccata, Suillis pseudobrevipes y Boletus clavipes en comparación con el testigo. La caracterización micromorfológica mostró una asociación típica de gimnospermas con una red de Hartig penetrando varias capas de células corticales.

Sensitivity of adult and embryonic calanoid copepods to acute ionizing radiation

International Nuclear Information System (INIS)

Gehrs, C.W.; Trabalka, J.R.; Bardill, E.A.

1975-01-01

Effects of 60 Co γ-rays on adult and embryonic calanoid copepods (Diaptomus clavipes Schact) were determined following acute doses of 0, 1, 10, and 100 krads. Mean survivorship of adults ranged from 3.1 to 45.2 days (100 krad and controls, respectively) and decreased significantly at each increase in dose. The 100-krad dose effected 100 percent mortality to all embryos. Whereas all clutches in the controls had some hatching success, a progressive increase in percentage of clutches in which no hatching took place was seen over the dose range used. Nearly twice as many clutches were dropped in the irradiated group as in the controls. While a significant decrease in hatching success with increasing dose was observed when all clutches were compared, this was not the case at the lowest dose for carried clutches. Possibly the females are able to assess the physiological state of the embryos carried and eject clutches containing damaged eggs. (U.S.)

Industrial Mining's flexibility aids in customer satisfaction

Energy Technology Data Exchange (ETDEWEB)

1985-08-01

Mining flexibility and customer specification keeps Industrial Mining of Youngstown, Ohio competitive in a tough environment. The company fills the needs of the small customer who requires a special blend or sized product. Industrial Mining works terrain that was uneconomical to mine before but is now profitable. Draglines and mobile equipment are used for overburden removal for economical and flexible mining with most mining by the contour method. Industrial Mining's preparation plant was constructed in 1979 to enable the company to wash and screen different stoker products and utility coal with a modern on-site lab a quality product can be constantly maintained. A wheel loader is used to feed the hopper from selective stockpiles and this allows blending on the raw side or within the plant.

Entangled Polymer Melts in Extensional Flow - Characterization by Combined Rheology and Small-Angle Neutron Scattering

DEFF Research Database (Denmark)

Mortensen, Kell; Kirkensgaard, Jacob JK; Hassager, Ole

Liquid bridges occur in a variety of situations in nature - yet our understanding of the dynamics and stability is very limited. Examples of liquid bridges are the process used byspiders to form draglines and the process used by cats lapping milk. We have an extendedprogram aiming to provide...... generic knowledge about the process in which macromolecular fluidfilaments are extended and stretched and show how the extensional properties are related to theproperties on individual molecules. We combine structural and rheological studies of a series ofmodel polymers with different composition...... and architectures. The project entails synthesizingmodel polymer systems of precisely known molecular architecture, subjecting these materials tocontrolled extensional flows and to measure the molecular deformation under controlled flowsituation by SANS. Neutron contrast is obtained using specific deuterium labeled...

Synthetic Adhesive Attachment Discs based on Spider Pyriform Silk Architecture

Science.gov (United States)

Jain, Dharamdeep; Sahni, Vasav; Dhinojwala, Ali

2014-03-01

Among the variety of silks produced by spiders, pyriform silk is used in conjunction with the dragline silk to attach webs to different surfaces. Cob weaver spiders employ different architectural patterns to utilize the pyriform silk and form attachment joints with each pattern having a characteristic adhesive performance. The staple pin architecture is a one of the strongest attachment designs employed by spiders to attach their webs. Here we use a synthetic approach to create the a similar patterned architecture attachment discs on aluminum substrate using thermoplastic polyurethane. Measurable pull off forces are generated when the synthetic discs are peeled off a surface. This innovative adhesive strategy can be a source of design in various biomedical applications. Financial Support from National Science Foundation.

Duplication and concerted evolution of MiSp-encoding genes underlie the material properties of minor ampullate silks of cobweb weaving spiders.

Science.gov (United States)

Vienneau-Hathaway, Jannelle M; Brassfield, Elizabeth R; Lane, Amanda Kelly; Collin, Matthew A; Correa-Garhwal, Sandra M; Clarke, Thomas H; Schwager, Evelyn E; Garb, Jessica E; Hayashi, Cheryl Y; Ayoub, Nadia A

2017-03-14

Orb-web weaving spiders and their relatives use multiple types of task-specific silks. The majority of spider silk studies have focused on the ultra-tough dragline silk synthesized in major ampullate glands, but other silk types have impressive material properties. For instance, minor ampullate silks of orb-web weaving spiders are as tough as draglines, due to their higher extensibility despite lower strength. Differences in material properties between silk types result from differences in their component proteins, particularly members of the spidroin (spider fibroin) gene family. However, the extent to which variation in material properties within a single silk type can be explained by variation in spidroin sequences is unknown. Here, we compare the minor ampullate spidroins (MiSp) of orb-weavers and cobweb weavers. Orb-web weavers use minor ampullate silk to form the auxiliary spiral of the orb-web while cobweb weavers use it to wrap prey, suggesting that selection pressures on minor ampullate spidroins (MiSp) may differ between the two groups. We report complete or nearly complete MiSp sequences from five cobweb weaving spider species and measure material properties of minor ampullate silks in a subset of these species. We also compare MiSp sequences and silk properties of our cobweb weavers to published data for orb-web weavers. We demonstrate that all our cobweb weavers possess multiple MiSp loci and that one locus is more highly expressed in at least two species. We also find that the proportion of β-spiral-forming amino acid motifs in MiSp positively correlates with minor ampullate silk extensibility across orb-web and cobweb weavers. MiSp sequences vary dramatically within and among spider species, and have likely been subject to multiple rounds of gene duplication and concerted evolution, which have contributed to the diverse material properties of minor ampullate silks. Our sequences also provide templates for recombinant silk proteins with tailored

Operational and geotechnical constraints to coal mining in Alaska's interior

Energy Technology Data Exchange (ETDEWEB)

Corser, P; Usibelli, M

1989-01-01

Surface mining of coal from the Poker Flats mining area to the north of Healy, Alaska began in 1978. Current operations involve a 25 m/sup 3/ walking dragline which strips two coal seams, using an extended bench on the second pass; a fleet of trucks and shovels are used for coal removal and some limited overburden stripping. Geotechnical constraints to mining within the steeply dipping coal deposits are discussed. The area had a number of landslides. During 1984, mining operations close to a landslide caused movement to resume. A mine plan was developed which allowed the coal to be safely removed without inducing additional movement. This involves a dipline mining scheme through the slide area. Future mine plans will acknowledge the hazards of mining through potentially unstable zones. Aerial photographs, field mapping and geological exploration were used. 1 ref., 6 figs.

Foundation of the Outstanding Toughness in Biomimetic and Natural Spider Silk.

Science.gov (United States)

Anton, Arthur Markus; Heidebrecht, Aniela; Mahmood, Nasir; Beiner, Mario; Scheibel, Thomas; Kremer, Friedrich

2017-12-11

Spider dragline silk is distinguished through the highest toughness of all natural as well as artificial fiber materials. To unravel the toughness's molecular foundation and to enable manufacturing biomimetic analogues, we investigated the morphological and functional structure of recombinant fibers, which exhibit toughness similar to that of the natural template, on the molecular scale by means of vibrational spectroscopy and on the mesoscale by X-ray scattering. Whereas the former was used to identify protein secondary structures and their alignment in the natural as well as artificial silks, the latter revealed nanometer-sized crystallites on the higher structural level. Furthermore, a spectral red shift of a crystal-specific absorption band demonstrated that macroscopically applied stress is directly transferred to the molecular scale, where it is finally dissipated. Concerning this feature, both the natural as well as the biomimetic fibers are almost indistinguishable, giving rise to the toughness of both fiber materials.

Data for ion and seed dependent fibril assembly of a spidroin core domain

Directory of Open Access Journals (Sweden)

Martin Humenik

2015-09-01

Full Text Available This data article includes size exclusion chromatography data of soluble eADF4(C16, an engineered spider silk variant based on the core domain sequence of the natural dragline silk protein ADF4 of Araneus diadematus, in combination with light scattering; the protein is monomeric before assembly. The assembled mature fibrils were visualized by transmission electron microscopy (TEM and atomic force microscopy (AFM. Sonicated fibrils were used as seeds to by-pass the nucleation lag phase in eADF4(C16 assembly. We also provide data on the sedimentation kinetics of spider silk in the presence of different NaCl concentrations revealing very slow protein aggregation in comparison to the fast assembly triggered by phosphate ions published previously [1]. Experiments in the Data article represent supporting material for our work published recently [1], which described the assembly mechanism of recombinant eADF4(C16 fibrils.

Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders

Directory of Open Access Journals (Sweden)

Suet Wai Yuen

2017-12-01

Full Text Available Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator–prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in Nephila pilipes orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution’s disruption of species interactions.

Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders.

Science.gov (United States)

Yuen, Suet Wai; Bonebrake, Timothy C

2017-01-01

Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator-prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in Nephila pilipes orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings) and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution's disruption of species interactions.

Characterization and assembly of a GFP-tagged cylindriform silk into hexameric complexes.

Science.gov (United States)

Öster, Carl; Svensson Bonde, Johan; Bülow, Leif; Dicko, Cedric

2014-04-01

Spider silk has been studied extensively for its attractive mechanical properties and potential applications in medicine and industry. The production of spider silk, however, has been lagging behind for lack of suitable systems. Our approach focuses on solving the production of spider silk by designing, expressing, purifying and characterizing the silk from cylindriform glands. We show that the cylindriform silk protein, in contrast to the commonly used dragline silk protein, is fully folded and stable in solution. With the help of GFP as a fusion tag we enhanced the expression of the silk protein in Escherichia coli and could optimize the downstream processing. Secondary structures analysis by circular dichroism and FTIR shows that the GFP-silk fusion protein is predominantly α-helical, and that pH can trigger a α- to β-transition resulting in aggregation. Structural analysis by small angle X-ray scattering suggests that the GFP-Silk exists in the form of a hexamer in solution. Copyright © 2013 Wiley Periodicals, Inc.

Non-cable vehicle guidance

Energy Technology Data Exchange (ETDEWEB)

Daugela, G.C.; Willott, A.M.; Chopiuk, R.G.; Thornton, S.E.

1988-06-01

The purpose is to determine the most promising driverless mine vehicle guidance systems that are not dependent on buried cables, and to plan their development. The project is presented in two phases: a preliminary study and literature review to determine whether suitable technologies exist to justify further work; and an in-depth assessment and selection of technologies for vehicle guidance. A large number of guidance elements are involved in a completely automated vehicle. The technologies that hold the best potential for development of guidance systems for mine vehicles are ultrasonics, radar, lasers, dead reckoning, and guidance algorithms. The best approach to adaptation of these technologies is on a step by step basis. Guidance modules that are complete in themselves and are designed to be integrated with other modules can provide short term benefits. Two modules are selected for development: the dragline operations monitor and automated machine control for optimized mining (AMCOM). 99 refs., 20 figs., 40 tabs.

Understanding hydrotransport : the key to Syncrude's success

International Nuclear Information System (INIS)

Paine, R.B.; Wright, B.M.

1998-01-01

Syncrude's use of pipeline slurries to convey oilsand from its Athabasca deposit to the extraction plant marks the beginning of a new era in oilsand processing. With this new conveyance system Syncrude plans to phase out the dragline, bucketwheel reclaimer, and conveyor ore mining and delivery system in favour of shovel, truck, and hydrotransport technology. Shovels will be used to mine the ore in a conventional open pit bench mining scheme. The oilsand will then be loaded onto trucks, hauled to a crusher for sizing and fed into the hydrotransport system where it will be slurried with water and caustic soda and pumped to the extraction plant by pipeline. The advantages of hydrotransport include significant energy savings and considerably less plant infrastructure. A new method to describe the source ore characteristics and plant performance was also developed. The use of this information system within the corporation is described. 7 refs., 3 figs

Syncrude's Aurora Mine : the key to future Athabasca oil sands development

International Nuclear Information System (INIS)

Kershaw, D.

1998-01-01

Syncrude's newest mine, the Aurora mine is located 35 km northeast of Syncrude's existing Mildred Lake plant, across the Athabasca River. It has a potential to produce more than 2.5 billion barrels of bitumen. Aurora will eventually consist of two surface mines, the Aurora North and Aurora South. Mining and extraction will occur at Aurora with the resulting bitumen transported as a froth by pipeline back to the existing plant for upgrading to Syncrude Sweet Blend. A total of 120 km of pipeline will be used. Syncrude has developed a new method of sending oilsand from its Athabasca deposit to the extraction plant. The company plans to phase out the dragline, bucketwheel reclaimer, and conveyor ore mining and delivery system in favour of shovel, truck, and hydrotransport technology. The advantages of hydrotransport include significant energy savings and considerably less plant infrastructure. A hydrotransport prototype is at work at Syncrude's base mine where it is responsible for 15 per cent of the production

Passive aerial dispersal of insects and other arthropods

Science.gov (United States)

Miller, Laura

2016-11-01

One of the defining features of the aerial dispersal of tiny organisms is the ability to overcome negative buoyancy. This can be accomplished by dispersing in the right wind conditions (e.g. an updraft) or by active flight or active release. Once in the air, draggy structures, such as the draglines of spiders or bristled wings of tiny insects, can reduce the settling velocity and extend the time of transport. Purely passive mechanisms allow spiders and other arthropods to drift on strands of silk to heights of 14,000 m and distances of hundreds of miles. Similarly, tiny insects like thrips and parasitoid wasps can travel distances of thousands to tens of thousands of meters, possibly using a combination of periods of active and passive flight. In this presentation, we used the immersed boundary method to quantify settling velocities and transport dynamics of parachuting insects and other arthropods within a quiescent fluid, a uniform updraft, and eddies.

The planning and operation of open-pit and strip mines: proceedings of an international conference held at the University of Pretoria, 9-13 April 1984

International Nuclear Information System (INIS)

Deetlefs, J.P.

1986-01-01

This book records the proceedings of the second international conference on the theme of planning and operation of open-pit and strip mines. The conference was held in Pretoria during April 1984. The major portion of South African iron ore and copper is mined in open-pit mines. The rapid expansion of the open-pit and strip mining industry has led to the thriving industry of today. Notable areas of growth have been the introduction of capital-intensive machinery such as walking drag-lines, large capacity shovels, in-pit crushers, extensive use of conveyor belts, large haul tracks and ore-dressing plants. Among other areas where corresponding progress has been made are blasting techniques, maintenance planning, computer applications, and large-scale stock-piling of bulk materials. The conference touched on all these subjects under four main headings: mine planning, mining operations, equipment selection and maintenance, and new developments. One paper looks at open-pit production control at Rossing Uranium Limited

Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes

Science.gov (United States)

Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M.; Gambhir, Sanjeev; Wallace, Gordon G.; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

2012-01-01

The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g-1, far exceeding spider dragline silk (165 J g-1) and Kevlar (78 J g-1). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs.

Review structure of silk by raman spectromicroscopy: from the spinning glands to the fibers.

Science.gov (United States)

Lefèvre, Thierry; Paquet-Mercier, François; Rioux-Dubé, Jean-François; Pézolet, Michel

2012-06-01

Raman spectroscopy has long been proved to be a useful tool to study the conformation of protein-based materials such as silk. Thanks to recent developments, linearly polarized Raman spectromicroscopy has appeared very efficient to characterize the molecular structure of native single silk fibers and spinning dopes because it can provide information relative to the protein secondary structure, molecular orientation, and amino acid composition. This review will describe recent advances in the study of the structure of silk by Raman spectromicroscopy. A particular emphasis is put on the spider dragline and silkworm cocoon threads, other fibers spun by orb-weaving spiders, the spinning dope contained in their silk glands and the effect of mechanical deformation. Taken together, the results of the literature show that Raman spectromicroscopy is particularly efficient to investigate all aspects of silk structure and production. The data provided can lead to a better understanding of the structure of the silk dope, transformations occurring during the spinning process, and structure and mechanical properties of native fibers. Copyright © 2011 Wiley Periodicals, Inc.

Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes.

Science.gov (United States)

Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M; Gambhir, Sanjeev; Wallace, Gordon G; Kozlov, Mikhail E; Baughman, Ray H; Kim, Seon Jeong

2012-01-31

The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g(-1), far exceeding spider dragline silk (165 J g(-1)) and Kevlar (78 J g(-1)). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs.

Enabling technologies for oil sands development

International Nuclear Information System (INIS)

Bailey, R.T.

1998-01-01

A review of oil sands production and expansion possibilities in Alberta were presented. The enabling technologies for oil sands projects include mining (bucketwheels, draglines, trucks, shovels conveyors, slurry hydrotransport); extraction (conditioning tumblers, pipelines, tanks, hot water, caustic, cold water, frothers); froth cleaning (centrifuges, solvent treatment); tailings (tailings ponds, consolidated tailings); and upgrading (coking, hydrotreating for SCO, hydrocracking and multiple products). The enabling technologies for in situ production include cyclic steam stimulation for vertical wells, steam assisted gravity drainage (SAGD) for dual horizontal wells, and cold production with wormholes. This paper described the recovery potentials of each of these processes. It also discussed the role of government and industry in research and cooperative research involving both the private and public sectors. Examples of each of these were described such as SAGD, the OSLO cold water extraction process, The consolidated tailings (CT) project, the low energy extraction process (slurry production, hydrotransport, pipeline conditioning and warm water extraction), and research in fine tailings, to demonstrate that although objectives may differ, government and industry research objectives are complementary

Radioactive contamination of arthropods from different trophic levels in hilly and mountainous areas after the Fukushima Daiichi nuclear power plant accident.

Science.gov (United States)

Tanaka, Sota; Hatakeyama, Kaho; Takahashi, Sentaro; Adati, Tarô

2016-11-01

In order to understand the influence of the Fukushima Daiichi nuclear power plant accident on the ecosystem in hilly and mountainous areas of Fukushima Prefecture, chronological changes in the levels of radiocesium in arthropod species were investigated. From 2012 to 2014, arthropods from different trophic levels were sampled and the air radiation dose rates at the sampling sites were analyzed. The air radiation dose rates showed a significant and constant reduction over the 2 years at the sampling sites in Fukushima. The median radiocesium concentration ( 134 Cs +  137 Cs) detected in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, dropped continuously to 0.080 and 0.078 Bq/g fresh weight, respectively, in 2014. In contrast, no significant reduction in radioactive contamination was observed in the Jorô spider, Nephila clavata, in which the level remained at 0.204 Bq/g in 2014. A significant positive correlation between radiocesium concentration and the air radiation dose rate was observed in the rice grasshopper, the Emma field cricket and the Jorô spider. The highest correlation coefficient (ρ = 0.946) was measured in the grasshopper. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

How a Huottuja (Piaroa community perceives genuine and false honey from the Venezuelan Amazon, by free-choice profi le sensory method

Directory of Open Access Journals (Sweden)

Patricia Vit

2011-06-01

Full Text Available Pot honey is the most abundant honey in the forest, produced by many species of stingless bees (Meliponini of the Huottuja (Piaroa community in Paria Grande, Venezuela. However, the commercialization of this honey is low, and false honeys, which are sold in labelled bottles, are easily found in the market. This study has investigated the ability of an untrained panel of Piaroa assessors to differentiate the genuine from the false pot honey using the Free-choice profile. This sensory method allows consumers to use their own words to describe and to quantify sensory attributes of a product. The genuine honeys, light amber Melipona fuscopilosa "isabitto" and dark amber Tetragona clavipes "ajavitte", the false light and dark "angelita" honeys, and the amber Apis mellifera honey, were evaluated. Sensory attributes related to the appearance, color, odor, flavor and mouthfeel were elicited in a qualitative session and were quantified in 10-cm unstructured line scales using individual score sheets. The data were analyzed by Generalized Procrustes Analysis (GPA. The bidimensional plot successfully separated genuine from false pot honeys. The first dimension (39.50% was represented by the low viscosity, fermented odor and sour taste, whereas the second dimension (24.69% was related to fruity and honey odor and flavor. Huottuja assessors differentiated the five honey types in terms of the perceived sensory characteristics.

How a Huottuja (Piaroa community perceives genuine and false honey from the Venezuelan Amazon, by free-choice profi le sensory method

Directory of Open Access Journals (Sweden)

Patricia Vit

2011-10-01

Full Text Available Pot honey is the most abundant honey in the forest, produced by many species of stingless bees (Meliponini of the Huottuja (Piaroa community in Paria Grande, Venezuela. However, the commercialization of this honey is low, and false honeys, which are sold in labelled bottles, are easily found in the market. This study has investigated the ability of an untrained panel of Piaroa assessors to differentiate the genuine from the false pot honey using the Free-choice profile. This sensory method allows consumers to use their own words to describe and to quantify sensory attributes of a product. The genuine honeys, light amber Melipona fuscopilosa "isabitto" and dark amber Tetragona clavipes "ajavitte", the false light and dark "angelita" honeys, and the amber Apis mellifera honey, were evaluated. Sensory attributes related to the appearance, color, odor, flavor and mouthfeel were elicited in a qualitative session and were quantified in 10-cm unstructured line scales using individual score sheets. The data were analyzed by Generalized Procrustes Analysis (GPA. The bidimensional plot successfully separated genuine from false pot honeys. The first dimension (39.50% was represented by the low viscosity, fermented odor and sour taste, whereas the second dimension (24.69% was related to fruity and honey odor and flavor. Huottuja assessors differentiated the five honey types in terms of the perceived sensory characteristics.

Peabody Western brings its old mines into new competitive era

Energy Technology Data Exchange (ETDEWEB)

Sprouls, M.W.

1994-10-01

Peabody Western Coal Co., manages four surface mines that mark Peabody's expansion from the Midwest to the West. The mines began operating between 1964 and 1973, before the surge of western coal mine start-ups brought about by the oil price shock of 1973 and 1974 and the subsequent investments in coal by American oil companies. Despite good demand for western low-sulfur coals, the prices are low due to production overcapacity that was built in the 1970s. The result is that older mines have had to be creative to reduce costs and retain customers amid stiff competition. The mining units - Black Mesa and Kayenta in Arizona, Big Sky in Montana and Seneca in Colorado - now must handle coal supply administration, financial analysis, engineering, environmental compliance, labor relations and community relations at their sites. Peabody Western's Flagstaff, Ariz., headquarters staff will be reduced by about 30 people, although many of them will be assigned to mining units. All four surface mines use draglines, and each supplies a primary customer, but the mines have as many differences as similarities. Altogether, the mines produce about 17 million tons annually and employ 1,100 people.

An Alien in the Group: Eusocial Male Bees Sharing Nonspecific Reproductive Aggregations

Science.gov (United States)

dos Santos, C. F.; Ferreira-Caliman, M. J.; Nascimento, F. S.

2015-01-01

Sexual selection predicts that individuals competing for access to sexual partners should maximize their chances of mating by looking for sites where the chances of finding partners are more likely to occur. However, males of stingless bees have been observed sharing nonspecific reproductive aggregations. This uncommon behavior appears to confer no obvious increase of individual fitness. It has been suggested that this reproductive strategy is due to the similarity between male odors common to different stingless bee species. Cuticular hydrocarbons (CHCs) are candidate odors of interest because their nonvolatile pheromone nature allows them to play an important role in sexual behavior and species recognition. Here, we review the literature to evaluate whether any phylogenetic patterns exist among male stingless bees that aggregate with closely or distantly related species. We also compared the CHC profiles of males of Neotropical stingless bee species (Plebeia sp. Schwarz, Trigona spinipes (F.), Tetragona clavipes (F.), Nannotrigona testaceicornis (Lepeletier), Scaptotrigona aff. depilis (Moure), Tetragonisca angustula (Latreille), and Melipona subnitida (Ducke) to reveal any chemical similarities among their male odors. We found males of 21 stingless bee species involved in interspecific interactions mainly from Neotropical and Indo-Malayan/Australasian regions. Alien males did not necessarily visit host aggregations of closely related species. Furthermore, the CHC profiles of different studied species were very distinct from each other and do not overlapped at all. It is unclear yet why this apparently nonadaptive behavior carried out by some stingless bee males. PMID:26518220

Detection and phylogenetic analysis of bacteriophage WO in spiders (Araneae).

Science.gov (United States)

Yan, Qian; Qiao, Huping; Gao, Jin; Yun, Yueli; Liu, Fengxiang; Peng, Yu

2015-11-01

Phage WO is a bacteriophage found in Wolbachia. Herein, we represent the first phylogenetic study of WOs that infect spiders (Araneae). Seven species of spiders (Araneus alternidens, Nephila clavata, Hylyphantes graminicola, Prosoponoides sinensis, Pholcus crypticolens, Coleosoma octomaculatum, and Nurscia albofasciata) from six families were infected by Wolbachia and WO, followed by comprehensive sequence analysis. Interestingly, WO could be only detected Wolbachia-infected spiders. The relative infection rates of those seven species of spiders were 75, 100, 88.9, 100, 62.5, 72.7, and 100 %, respectively. Our results indicated that both Wolbachia and WO were found in three different body parts of N. clavata, and WO could be passed to the next generation of H. graminicola by vertical transmission. There were three different sequences for WO infected in A. alternidens and two different WO sequences from C. octomaculatum. Only one sequence of WO was found for the other five species of spiders. The discovered sequence of WO ranged from 239 to 311 bp. Phylogenetic tree was generated using maximum likelihood (ML) based on the orf7 gene sequences. According to the phylogenetic tree, WOs in N. clavata and H. graminicola were clustered in the same group. WOs from A. alternidens (WAlt1) and C. octomaculatum (WOct2) were closely related to another clade, whereas WO in P. sinensis was classified as a sole cluster.

Instantaneous angular speed monitoring of gearboxes under non-cyclic stationary load conditions

Science.gov (United States)

Stander, C. J.; Heyns, P. S.

2005-07-01

Recent developments in the condition monitoring and asset management market have led to the commercialisation of online vibration-monitoring systems. These systems are primarily utilised to monitor large mineral mining equipment such as draglines, continuous miners and hydraulic shovels. Online monitoring systems make diagnostic information continuously available for asset management, production outsourcing and maintenance alliances with equipment manufacturers. However, most online vibration-monitoring systems are based on conventional vibration-monitoring technologies, which are prone to giving false equipment deterioration warnings on gears that operate under fluctuating load conditions. A simplified mathematical model of a gear system was developed to illustrate the feasibility of monitoring the instantaneous angular speed (IAS) as a means of monitoring the condition of gears that are subjected to fluctuating load conditions. A distinction is made between cyclic stationary load modulation and non-cyclic stationary load modulation. It is shown that rotation domain averaging will suppress the modulation caused by non-cyclic stationary load conditions but will not suppress the modulation caused by cyclic stationary load conditions. An experimental investigation on a test rig indicated that the IAS of a gear shaft could be monitored with a conventional shaft encoder to indicate a deteriorating gear fault condition.

Collapse settlement of wetted mine waste - two case histories

International Nuclear Information System (INIS)

Peterson, T.W.; Wade, N.H.

1997-01-01

Two separate projects, constructed on reclaimed coal mine waste at TransAlta's Highvale Mine complex in west-central Alberta, experienced significant settlements as a result of groundwater recharge. One project, a new service building for large coal haulers and other heavy mining equipment, was constructed in 1981 on a thick, compacted fly ash raft overlying 15 m of dynamically compacted mine waste. Little if any building settlement was observed for the first few years after construction at which time progressive differential settlements were experienced that were related to unanticipated groundwater recharge. The second project, the diversion of an environmentally sensitive creek away from the active mining area, involved the construction of a 1.5 km canal and a 5 m high stepped drop structure over dragline-dumped waste up to 20 m thick. Pre-compression of the mine waste beneath the drop structure was effected by water injection through a series of wells installed in the structure footprint prior to construction. This paper outlines the methods of construction, investigations conducted, confirmatory field test procedures and settlements measured at both projects and, based on the findings, provides guidelines for possible mitigative measures in reducing saturation-induced settlements in future developments on reclaimed land. 6 refs., 10 figs

1967 : six days on the front

Energy Technology Data Exchange (ETDEWEB)

Anon.

2008-06-15

Canada's first oil sands project was launched by the Great Canadian Oil Sands Company in 1967 near Fort McMurray, Alberta. Giant draglines and bucketwheel excavators were used to mine the abrasive bitumen-laden sands. The first Middle East crisis also spiked demand for Canadian oil. The combined output from Algeria, Libya, Egypt and the Persian Gulf countries was 11.5 million barrels per day compared to just under 27 million barrels per day total free world production. The short crisis directly threatened Quebec and the Atlantic provinces which were entirely dependent on imported petroleum. Although western Canada had the ability to increase production by nearly 300,000 barrels per day, inadequate pipeline capacity impeded delivery of Canadian oil to these provinces. Following the crisis, production from the Persian Gulf and North Africa actually increased by 900,000 barrels per day. The long-term effect of the crisis was the closing of the Suez Canal for 8 years, depriving it of tariff revenues and permanently changing world shipping routes. In 1967, the first liquefied natural gas plant also came on stream in Vancouver, and Mobil Oil drilled a 15,000-foot exploratory well on Sable Island, Nova Scotia. 1 tab., 1 fig.

Mining in 2015

Energy Technology Data Exchange (ETDEWEB)

Hood, M.; Hatherly, P.; Gurgenci, H. [Centre for Mining Technology and Equipment (Australia)

1999-10-01

New technology in open-pit and underground hard rock mining in 2015 is anticipated in this article, based on a paper presented to the 1998 invitation symposium - 'Technology - Australia's future: new technology for traditional industry', held in Freemantle, WA, 24-25 November 1998. It is expected that essential mining operations of rock breakage and transport and ore processing will still exist but the use of drills, shovels/LHDs and trucks is likely to be replaced by continuous, intelligent, automated mining systems. Rock blasting models need to be fed data on rock properties at each blasthole for high accuracy. The authors believe that in 2015 measurements of rock properties will be a routine part of the drilling process. Blasthole drills will be fitted with a range of mechanical and geophysical sensors. New, non-explosive methods of rock breaking such as oscillating disc cutting, may be available. Mining automation will improve safety and productivity, perhaps with the automation of dragline swing LHDs and trucks may be able to drive themselves, with operators monitoring and intervening when necessary. Performance and machine condition data may be applied to improve equipment design. Australian mining stands to gain by these advances in mining technology. 1 fig., 3 photos.

Distinct spinning patterns gain differentiated loading tolerance of silk thread anchorages in spiders with different ecology.

Science.gov (United States)

Wolff, Jonas O; van der Meijden, Arie; Herberstein, Marie E

2017-07-26

Building behaviour in animals extends biological functions beyond bodies. Many studies have emphasized the role of behavioural programmes, physiology and extrinsic factors for the structure and function of buildings. Structure attachments associated with animal constructions offer yet unrealized research opportunities. Spiders build a variety of one- to three-dimensional structures from silk fibres. The evolution of economic web shapes as a key for ecological success in spiders has been related to the emergence of high performance silks and thread coating glues. However, the role of thread anchorages has been widely neglected in those models. Here, we show that orb-web (Araneidae) and hunting spiders (Sparassidae) use different silk application patterns that determine the structure and robustness of the joint in silk thread anchorages. Silk anchorages of orb-web spiders show a greater robustness against different loading situations, whereas the silk anchorages of hunting spiders have their highest pull-off resistance when loaded parallel to the substrate along the direction of dragline spinning. This suggests that the behavioural 'printing' of silk into attachment discs along with spinneret morphology was a prerequisite for the evolution of extended silk use in a three-dimensional space. This highlights the ecological role of attachments in the evolution of animal architectures. © 2017 The Author(s).

Virus epidemics can lead to a population-wide spread of intragenomic parasites in a previously parasite-free asexual population.

Science.gov (United States)

Jalasvuori, Matti; Lehtonen, Jussi

2014-03-01

Sexual reproduction is problematic to explain due to its costs, most notably the twofold cost of sex. Yet, sex has been suggested to be favourable in the presence of proliferating intragenomic parasites given that sexual recombination provides a mechanism to confine the accumulation of deleterious mutations. Kraaijeveld et al. compared recently the accumulation of transposons in sexually and asexually reproducing lines of the same species, the parasitoid wasp Leptopilina clavipes. They discovered that within asexually reproducing wasps, the number of gypsy-like retrotransposons was increased fourfold, whereas other retrotransposons were not. Interestingly, gypsy-like retrotransposons are closely related to retroviruses. Endogenous retroviruses are retroviruses that have integrated to the germ line cells and are inherited thereafter vertically. They can also replicate within the genome similarly to retrotransposons as well as form virus particles and infect previously uninfected cells. This highlights the possibility that endogenous retroviruses could play a role in the evolution of sexual reproduction. Here, we show with an individual-based computational model that a virus epidemic within a previously parasite-free asexual population may establish a new intragenomic parasite to the population. Moreover and in contrast to other transposons, the possibility of endogenous viruses to maintain a virus epidemic and simultaneously provide resistance to individuals carrying active endogenous viruses selects for the presence of active intragenomic parasites in the population despite their deleterious effects. Our results suggest that the viral nature of certain intragenomic parasites should be taken into account when sex and its benefits are being considered. © 2014 John Wiley & Sons Ltd.

Molecular components and toxicity of the venom of the solitary wasp, Anoplius samariensis

International Nuclear Information System (INIS)

Hisada, Miki; Satake, Honoo; Masuda, Katsuyoshi; Aoyama, Masato; Murata, Kazuya; Shinada, Testuro; Iwashita, Takashi; Ohfune, Yasufumi; Nakajima, Terumi

2005-01-01

The solitary spider wasp, Anoplius samariensis, is known to exhibit a unique long-term, non-lethal paralysis in spiders that it uses as a food source for its larvae. However, neither detailed venom components nor paralytic compounds have ever been characterized. In this study, we examined the components in the low molecular weight fraction of the venom and the paralytic activity of the high molecular weight fraction. The major low molecular weight components of the venom were identified as γ-aminobutyric acid and glutamic acid by micro-liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance spectrometry analysis. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass analysis revealed that the A. samariensis venom contained the various proteins with weights of 4-100 kDa. A biological assay using Joro spiders (Nephila clavata) clearly showed that the high molecular weight fraction of the venom prepared by ultrafiltration exerted as potent non-lethal long-term paralysis as the whole venom, whereas the low molecular weight fraction was devoid of any paralytic activity. These results indicated that several venomous proteins in the high molecular weight fraction are responsible for the paralytic activity. Furthermore, we determined the primary structure of one component designated As-fr-19, which was a novel multiple-cysteine peptide with high sequence similarity to several sea anemone and snake toxins including dendrotoxins, rather than any insect toxic peptides identified so far. Taken together, our data showed the unprecedented molecular and toxicological profiles of wasp venoms

A proposal of Transport System Improvement in exploiting and processing of raw materials

Directory of Open Access Journals (Sweden)

Ján Sciranko

2006-09-01

Full Text Available In handling earth, aggregate rock, ore, coal and other materials, trucks serve one purpose. They are hauling units which, because of their high speed when operating on suitable roads, have high capacities and provide relatively low hauling costs.They provide a high degree of flexibility as their number may be decreased or increased easily to permit modifications in the total hauling capacity of a fleet.In cyclic operations, the two principal operations are loading and haulage with hoisting as a third optional. In continuous operations, where machines combine the breakage and handling functions, cutting, drilling and blasting are eliminated and extraction and loading are performed in a single operation or function (excavation, e.g. the bucket wheel excavator, auger, highwall mines, continuous miner or the boring machine.Materials handling in modern mechanized mining is equipment oriented. Unit operations are characterized by, and sometimes identified with, an equipment that performs them. Thus the field terminology refers to a mining shovel, stripping dragline or the coal loader. From time to time the mining engineer is faced with the necessity to make a haulage study to determine not only the most suitable method of hauling materials, but also the most effective and economical type of equipment used for the operation. Key words: truck haulage, material handling, mining shovel

Photoluminescent properties of spider silk coated with Eu-doped nanoceria

Energy Technology Data Exchange (ETDEWEB)

Dmitrović, Svetlana, E-mail: svetlana8@vin.bg.ac.rs [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia); Nikolić, Marko G.; Jelenković, Branislav [University of Belgrade, Institute of Physics (Serbia); Prekajski, Marija [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia); Rabasović, Mihailo [University of Belgrade, Institute of Physics (Serbia); Zarubica, Aleksandra [University of Niš, Department of Chemistry, Faculty of Science and Mathematics (Serbia); Branković, Goran [University of Belgrade, Institute for Multidisciplinary Research, Department of Material Science (Serbia); Matović, Branko [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia)

2017-02-15

Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silk mesh into aqueous solutions of cerium nitrate (Ce(NO{sub 3}){sub 3}) and ammonium hydroxide (NH{sub 4}OH). Depending on the relationship between Ce{sup 3+} ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

Hagfish slime threads as a biomimetic model for high performance protein fibres

International Nuclear Information System (INIS)

Fudge, Douglas S; Hillis, Sonja; Levy, Nimrod; Gosline, John M

2010-01-01

Textile manufacturing is one of the largest industries in the world, and synthetic fibres represent two-thirds of the global textile market. Synthetic fibres are manufactured from petroleum-based feedstocks, which are becoming increasingly expensive as demand for finite petroleum reserves continues to rise. For the last three decades, spider silks have been held up as a model that could inspire the production of protein fibres exhibiting high performance and ecological sustainability, but unfortunately, artificial spider silks have yet to fulfil this promise. Previous work on the biomechanics of protein fibres from the slime of hagfishes suggests that these fibres might be a superior biomimetic model to spider silks. Based on the fact that the proteins within these 'slime threads' adopt conformations that are similar to those in spider silks when they are stretched, we hypothesized that draw processing of slime threads should yield fibres that are comparable to spider dragline silk in their mechanical performance. Here we show that draw-processed slime threads are indeed exceptionally strong and tough. We also show that post-drawing steps such as annealing, dehydration and covalent cross-linking can dramatically improve the long-term dimensional stability of the threads. The data presented here suggest that hagfish slime threads are a model that should be pursued in the quest to produce fibres that are ecologically sustainable and economically viable.

Photoluminescent properties of spider silk coated with Eu-doped nanoceria

International Nuclear Information System (INIS)

Dmitrović, Svetlana; Nikolić, Marko G.; Jelenković, Branislav; Prekajski, Marija; Rabasović, Mihailo; Zarubica, Aleksandra; Branković, Goran; Matović, Branko

2017-01-01

Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silk mesh into aqueous solutions of cerium nitrate (Ce(NO_3)_3) and ammonium hydroxide (NH_4OH). Depending on the relationship between Ce"3"+ ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

Bat Predation by Spiders

Science.gov (United States)

Nyffeler, Martin; Knörnschild, Mirjam

2013-01-01

In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (∼90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed. PMID:23516436

Bat predation by spiders.

Science.gov (United States)

Nyffeler, Martin; Knörnschild, Mirjam

2013-01-01

In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (≈ 90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed.

Electrospun Collagen/Silk Tissue Engineering Scaffolds: Fiber Fabrication, Post-Treatment Optimization, and Application in Neural Differentiation of Stem Cells

Science.gov (United States)

Zhu, Bofan

Biocompatible scaffolds mimicking the locally aligned fibrous structure of native extracellular matrix (ECM) are in high demand in tissue engineering. In this thesis research, unidirectionally aligned fibers were generated via a home-built electrospinning system. Collagen type I, as a major ECM component, was chosen in this study due to its support of cell proliferation and promotion of neuroectodermal commitment in stem cell differentiation. Synthetic dragline silk proteins, as biopolymers with remarkable tensile strength and superior elasticity, were also used as a model material. Good alignment, controllable fiber size and morphology, as well as a desirable deposition density of fibers were achieved via the optimization of solution and electrospinning parameters. The incorporation of silk proteins into collagen was found to significantly enhance mechanical properties and stability of electrospun fibers. Glutaraldehyde (GA) vapor post-treatment was demonstrated as a simple and effective way to tune the properties of collagen/silk fibers without changing their chemical composition. With 6-12 hours GA treatment, electrospun collagen/silk fibers were not only biocompatible, but could also effectively induce the polarization and neural commitment of stem cells, which were optimized on collagen rich fibers due to the unique combination of biochemical and biophysical cues imposed to cells. Taken together, electrospun collagen rich composite fibers are mechanically strong, stable and provide excellent cell adhesion. The unidirectionally aligned fibers can accelerate neural differentiation of stem cells, representing a promising therapy for neural tissue degenerative diseases and nerve injuries.

Rock fragmentation control in opencast blasting

Directory of Open Access Journals (Sweden)

P.K. Singh

2016-04-01

Full Text Available The blasting operation plays a pivotal role in the overall economics of opencast mines. The blasting sub-system affects all the other associated sub-systems, i.e. loading, transport, crushing and milling operations. Fragmentation control through effective blast design and its effect on productivity are the challenging tasks for practicing blasting engineer due to inadequate knowledge of actual explosive energy released in the borehole, varying initiation practice in blast design and its effect on explosive energy release characteristic. This paper describes the result of a systematic study on the impact of blast design parameters on rock fragmentation at three mines in India. The mines use draglines and shovel–dumper combination for removal of overburden. Despite its pivotal role in controlling the overall economics of a mining operation, the expected blasting performance is often judged almost exclusively on the basis of poorly defined parameters such as powder factor and is often qualitative which results in very subjective assessment of blasting performance. Such an approach is very poor substitutes for accurate assessment of explosive and blasting performance. Ninety one blasts were conducted with varying blast designs and charging patterns, and their impacts on the rock fragmentation were documented. A high-speed camera was deployed to record the detonation sequences of the blasts. The efficiency of the loading machines was also correlated with the mean fragment size obtained from the fragmentation analyses.

Managing Japanese barberry (Ranunculales: Berberidaceae) infestations reduces blacklegged tick (Acari: Ixodidae) abundance and infection prevalence with Borrelia burgdorferi (Spirochaetales: Spirochaetaceae).

Science.gov (United States)

Williams, Scott C; Ward, Jeffrey S; Worthley, Thomas E; Stafford, Kirby C

2009-08-01

In many Connecticut forests with an overabundance of white-tailed deer (Odocoileus virginianus Zimmermann), Japanese barberry (Berberis thunbergii DC) has become the dominant understory shrub, which may provide a habitat favorable to blacklegged tick (Ixodes scapularis Say) and white-footed mouse (Peromyscus leucopus Rafinesque) survival. To determine mouse and larval tick abundances at three replicate sites over 2 yr, mice were trapped in unmanipulated dense barberry infestations, areas where barberry was controlled, and areas where barberry was absent. The number of feeding larval ticks/mouse was recorded. Adult and nymphal ticks were sampled along 200-m draglines in each treatment, retained, and were tested for Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt, and Brenner) presence. Total first-captured mouse counts did not differ between treatments. Mean number of feeding larval ticks per mouse was highest on mice captured in dense barberry. Adult tick densities in dense barberry were higher than in both controlled barberry and no barberry areas. Ticks sampled from full barberry infestations and controlled barberry areas had similar infection prevalence with B. burgdorferi the first year. In areas where barberry was controlled, infection prevalence was reduced to equal that of no barberry areas the second year of the study. Results indicate that managing Japanese barberry will have a positive effect on public health by reducing the number of B. burgdorferi-infected blacklegged ticks that can develop into motile life stages that commonly feed on humans.

Investigation of efficiency of electric drive control system of excavator traction mechanism based on feedback on load

Science.gov (United States)

Kuznetsov, N. K.; Iov, I. A.; Iov, A. A.

2018-05-01

The article presents the results of a study of the efficiency of the electric drive control system of the traction mechanism of a dragline based on the use of feedback on load in the traction cable. The investigations were carried out using a refined electromechanical model of the traction mechanism, which took into account not only the elastic elements of the gearbox, the backlashes in it and the changes in the kinematic parameters of the mechanism during operation, but also the mechanical characteristics of the electric drive and the features of its control system. By mathematical modeling of the transient processes of the electromechanical system, it is shown that the introduction of feedback on the load in the elastic element allows one to reduce the dynamic loads in the traction mechanism and to limit the elastic oscillations of the actuating mechanism in comparison with the standard control system. Fixed as a general decrease in the dynamic load of the nodes of traction mechanism in the modes of loading and latching of the bucket, and a decrease the operating time of the mechanism at maximum load. At the same time, undesirable phenomena in the operation of the electric drive were also associated with the increase in the recovery time of the steady-state value of the speed of the actuating mechanism under certain operating conditions, which can lead to a decrease in the reliability of the mechanical part and the productivity of the traction mechanism.

Operation and manning of the Rietspruit opencast coal mine

Energy Technology Data Exchange (ETDEWEB)

McCracken, T; Ive, J I

1982-02-18

Four coal seams, with a total thickness of 16 m, are in production at this opencast mine in the Transvaal; the first coal was mined in 1978. The overburden is stripped by three draglines, and the coal is worked with one shovel and three front-end loaders. Daily production capacity is 28 000 t of coal. The preparation plant has a rated throughput of 1750 t of run-of-mine coal per hour. 5 mt of coal were mined in 1981 and dispatched to Richards Bay, from where the coal is shipped to Western industrial nations. Some 200 million R were invested in the opencast mine, the preparation plant and the infrastructure. Company policy is much concerned with the training and education of the people on the mine; 25% of the personnel attended training courses last year. Pay categories are established in relation to the Peterson evaluation plan; jobs are graded from Group 1 (the lowest) to Group 15 (the grade of the General Manager). The current minimum wage is 214 to 231 R and is well above the living level and the cost of living. The employees live in Company one-family houses, or in bachelor accommodation in the case of unmarried employees. The quality of housing is exactly the same for Blacks and Whites. The housing estates include recreational facilities, sportsfields, a primary school, a clinic, a central restaurant and shops. The present article also gives details of leave entitlements and pensions.

General synthesis of β-alanine-containing spider polyamine toxins and discovery of nephila polyamine toxins 1 and 8 as highly potent inhibitors of ionotropic glutamate receptors

DEFF Research Database (Denmark)

Lucas, Simon; Poulsen, Mette H; Nørager, Niels G

2012-01-01

Certain spiders contain large pools of polyamine toxins, which are putative pharmacological tools awaiting further discovery. Here we present a general synthesis strategy for this class of toxins and prepare five structurally varied polyamine toxins. Electrophysiological testing at three ionotrop...

Technical frontier : where creativity is a matter of survival

International Nuclear Information System (INIS)

Fergusson, D.

1999-01-01

The impacts that technological advances in oil sand mining have had on the heavy oil industry were discussed. At a July 1999 oil sands workshop an assembly of engineers from various technology firms discussed how technology has made heavy oil production viable. New technology has made it possible to cut oil sand production costs in half. Bitumen, which was once viewed as an uncompetitive resource, has been made competitive through innovations such as steam assisted gravity drainage (SAGD) and Vapex. Non-thermal production such as methods involving solvents rather than heat to make bitumen and heavy oil flow have also contributed to the success of oil sand mining. Both Syncrude and Suncor employ the SAGD process which makes use of two parallel horizontal wells. In this process, steam is injected into the top well to heat the oil making it flow and drop to the second well which recovers it. Syncrude's use of hydrotransport as a means of moving oil sands ore by pipeline has improved the energy efficiency at oil sand mining facilities which previously used the dragline method. Another technological innovation is a new water distillation system developed by Aqua Pure Inc. The new system uses a process of heating, reheating and compressing water vapour until the contaminants are separated from the water. The Taciuk processor, developed in Alberta, is currently being used in Australia. This thermal recovery process makes use of spent shale to provide heat. Canadian technology, particularly in the oil-sand development is in demand internationally. SAGD wells are in demand in Venezuela, Australia and Albania. 1 fig

Three-dimensional printing spiders: back-and-forth glue application yields silk anchorages with high pull-off resistance under varying loading situations.

Science.gov (United States)

Wolff, Jonas O; Herberstein, Marie E

2017-02-01

The anchorage of structures is a crucial element of construction, both for humans and animals. Spiders use adhesive plaques to attach silk threads to substrates. Both biological and artificial adhesive structures usually have an optimal loading angle, and are prone to varying loading situations. Silk anchorages, however, must cope with loading in highly variable directions. Here we show that the detachment forces of thread anchorages of orb-web spiders are highly robust against pulling in different directions. This is gained by a two-step back-and-forth spinning pattern during the rapid production of the adhesive plaque, which shifts the thread insertion point towards the plaque centre and forms a flexible tree root-like network of branching fibres around the loading point. Using a morphometric approach and a tape-and-thread model we show that neither area, nor width of the plaque, but the shift of the loading point towards the plaque centre has the highest effect on pull-off resistance. This is explained by a circular propagation of the delamination crack with a low peeling angle. We further show that silken attachment discs are highly directional and adjusted to provide maximal performance in the upstream dragline. These results show that the way the glue is applied, crucially enhances the toughness of the anchorage without the need of additional material intake. This work is a starting point to study the evolution of tough and universal thread anchorages among spiders, and to develop bioinspired 'instant' anchorages of thread- and cable-like structures to a broad bandwidth of substrates. © 2017 The Author(s).

Characterization and Schwann Cell Seeding of up to 15.0 cm Long Spider Silk Nerve Conduits for Reconstruction of Peripheral Nerve Defects

Directory of Open Access Journals (Sweden)

Tim Kornfeld

2016-11-01

Full Text Available Nerve reconstruction of extended nerve defect injuries still remains challenging with respect to therapeutic options. The gold standard in nerve surgery is the autologous nerve graft. Due to the limitation of adequate donor nerves, surgical alternatives are needed. Nerve grafts made out of either natural or artificial materials represent this alternative. Several biomaterials are being explored and preclinical and clinical applications are ongoing. Unfortunately, nerve conduits with successful enhancement of axonal regeneration for nerve defects measuring over 4.0 cm are sparse and no conduits are available for nerve defects extending to 10.0 cm. In this study, spider silk nerve conduits seeded with Schwann cells were investigated for in vitro regeneration on defects measuring 4.0 cm, 10.0 cm and 15.0 cm in length. Schwann cells (SCs were isolated, cultured and purified. Cell purity was determined by immunofluorescence. Nerve grafts were constructed out of spider silk from Nephila edulis and decellularized ovine vessels. Finally, spider silk implants were seeded with purified Schwann cells. Cell attachment was observed within the first hour. After 7 and 21 days of culture, immunofluorescence for viability and determination of Schwann cell proliferation and migration throughout the conduits was performed. Analyses revealed that SCs maintained viable (>95% throughout the conduits independent of construct length. SC proliferation on the spider silk was determined from day 7 to day 21 with a proliferation index of 49.42% arithmetically averaged over all conduits. This indicates that spider silk nerve conduits represent a favorable environment for SC attachment, proliferation and distribution over a distance of least 15.0 cm in vitro. Thus spider silk nerve implants are a highly adequate biomaterial for nerve reconstruction.

Construction and modernization of underground and surface mines. [USSR

Energy Technology Data Exchange (ETDEWEB)

Burshtein, N M

1983-12-01

Development of the Sredazugol' association in Soviet Central Asia from 1976 to 1985 is discussed. From 1976 to 1980 investment in the association amounted to 151 million rubles, 87.5 million of which fell on construction. Major development projects of the 1976-1980 period are reviewed: construction of new mining levels in underground coal mines, development of a number of operating surface mines, modernization of earthmoving and mining equipment, development of mine haulage by locomotives and railroad cars, improving occupational safety in coal mining, increasing slope stability in surface mining, especially in the area of the Atchinsk landslide in the Angren mine. From 1981 to 1985 investment in the Sredazugol' association should amount to 202 million rubles, of which 126 million rubles will be spent on construction. Investment will be 35% higher than in the 1976-1980 period and investment in mine construction 43% higher. The largest development project will be modernization of the Angren surface mine and increasing its targeted coal output from 5.2 Mt/y to 10.3 Mt/y by 1990. Modernization and reconstruction of the Angren mine will be carried out in 2 stages. Coal output of the mine will increase by 1.2 Mt/y in the current 5 year plan (by 1985), and by 3.9 Mt/y in the next 5 year period. Reconstruction and development of the Angren mine will cost approximately 254 million rubles. Mining and earthmoving equipment which will be used in the Angren mine is reviewed: EhRGV-630 bucket wheel excavators, EhSh-10/70 and EhSh-13/50 walking draglines, etc.

Tests for attraction to prey and predator avoidance by chemical cues in spiders of the beech forest floor

Directory of Open Access Journals (Sweden)

Wetter, Melissa B.

2012-07-01

Full Text Available Spiders leave draglines, faeces and other secretions behind when traveling through their microhabitat. The presence of these secretions may unintentionally inform other animals, prey as well as predators, about a recent and possible current predation risk or food availability. For a wolf spider, other spiders including smaller conspecifics, form a substantial part of their prey, and larger wolf spiders, again including conspecifics, are potential predators. We tested two hypotheses: that large wolf spiders may locate patches of potential spider prey through the presence of silk threads and/or other secretions; and that prey spiders may use secretions from large wolf spiders to avoid patches with high predation risk. We used large (subadult or adult Pardosa saltans to provide predator cues and mixed dwarf spiders or small (juvenile P. saltans to provide prey cues. Subadult wolf spiders were significantly attracted to litter contaminated by dwarf spiders or small conspecifics after 6 hours but no longer after 24 hours. In contrast, neither dwarf spiders nor small P. saltans showed significant avoidance of substrate contaminated by adult P. saltans. However, small P. saltans showed different activity patterns on the two substrates. The results indicate that wolf spiders are able to increase the efficiency of foraging by searching preferentially in patches with the presence of intraguild prey. The lack of a clear patch selection response of the prey in spite of a modified activity pattern may possibly be associated with the vertical stratification of the beech litter habitat: the reduced volume of spaces in the deeper layers could make downward rather than horizontal movement a fast and safe tactic against a large predator that cannot enter these spaces.

Spider silk MASP1 and MASP2 proteins as carbon fiber precursors

Energy Technology Data Exchange (ETDEWEB)

Lewis, Randolph V [Utah State Univ., Logan, UT (United States)

2017-06-14

The objective of this project is to develop an unconventional non-petroleum based carbon fiber precursor which has the potential to be produced in high yield and quantities. Methods will be developed to produce pilot-scale quantities of fibers from spider silk proteins with mechanical properties at least 75% that of the natural dragline silk fibers in tensile strength and elongations of less than 5%. The precursor fibers will be converted to carbon fibers, with a goal of >250Ksi strength and 1-2% elongation. Cost analysis will be performed and the process optimized. Task 1: Subtask 1. Protein production: We exceeded the go/ no go milestone of 1.0g/L of one of the spider silk protein (MSp2) purified last FY and have now increased from 5L to 500L fermentations. We have made a series of changes to the purification protocol from the initial report last FY. These led to a reduction in the time needed for the purification and reduced the purification costs by nearly 90%. Subtask 2. Fiber spinning: The major focus has been to produce more material to send 24 fiber thread to ONRL. We are still developing the methodology to successfully spin 24 fiber yarns. This involves both the spinning dope solutions as well as the methods to keep the fibers from fusing during the post spin stretch. The second area of focus has been to standardize the spin dopes for making the fibers. We now know that the conductivity (indicative of salt remaining with the protein after purification) is an important factor in successful spinning as is the pH. We now know that we need to be below 600 uS conductivity and that the most effective pH is protein dependent. Subtask 3. Silkworm silk: We have found the transgenic silkworms made using gene replacement at the fibroin light chain instead of heavy chain as we did previously have a higher tensile strength. See figures below showing the curve for the top end of the cocoon fibers. This tensile strength is the same as the average for spider dragline silk

Taxonomía de onicóforos de Santander, Colombia y termogravimetría, calorimetría de barrido diferencial y espectroscopía infrarroja de la secreción adhesiva (Onychophora: Peripatidae

Directory of Open Access Journals (Sweden)

Javier H Jerez-Jaimes

2009-09-01

Full Text Available Redescribimos taxonómicamente el gusano Macroperipatus geagy Bouvier 1899, a partir de 15 especímenes recolectados en los cafetales de hacienda El Roble, Santander, Colombia. De acuerdo con la reconstrucción en tres dimensiones de la superficie dorsal del cuerpo, las papilas primarias y accesorias de M. geagy se distribuyen sin formar un patrón determinado. Características diagnósticas: un diente accesorio y un diente principal en la mandíbula externa; y un diente principal, un diente accesorio y siete dentículos en la sierra de la mandíbula interna. Cuerpo: longitud (X=45.66; S=26.10 mm, peso (X= 0.95; S= 2.21 y pares de lobopodos (X= 28.13; S= 1.30. Se elaboró una clave para seis especies de Macroperipatus. La secreción adhesiva en estado líquido perdió 60% del peso inicial al alcanzar los 70 ºC, la muestra sólida perdió el 13% del peso cerca de los 90 ºC, la fase de estabilidad térmica de la secreción estuvo entre los 90 y 280 ºC en la secreción líquida y entre los 100 y 205 ºC en la sólida. La temperatura de inicio de la degradación de las muestras se registró a los 355 ºC. En comparación con la araña Nephila sp., el onicóforo perdió mayor porcentaje de peso y alcanzó la fase de degradación a temperaturas más bajas. Los cambios en el flujo de calor en la secreción adhesiva sólida y líquida de M. geagy fueron confirmados con el comportamiento de las muestras en el análisis de termogravimetría. La proporción de láminas beta calculado en el espectro infrarrojo de la secreción adhesiva fue del 59%. La presencia de este tipo de conformación de la estructura secundaria de las proteínas en la secreción adhesiva de M. geagy conferiría extensibilidad y resistencia a la tracción, en similitud con las fibras de seda tejidas por las arañas para depredación.Velvet worm taxonomy from Santander, Colombia and thermogravimetry, differential scanning calorimetry and infrared spectroscopy of the adhesive

Silk-based biomaterials functionalized with fibronectin type II promotes cell adhesion.

Science.gov (United States)

Pereira, Ana Margarida; Machado, Raul; da Costa, André; Ribeiro, Artur; Collins, Tony; Gomes, Andreia C; Leonor, Isabel B; Kaplan, David L; Reis, Rui L; Casal, Margarida

2017-01-01

The objective of this work was to exploit the fibronectin type II (FNII) module from human matrix metalloproteinase-2 as a functional domain for the development of silk-based biopolymer blends that display enhanced cell adhesion properties. The DNA sequence of spider dragline silk protein (6mer) was genetically fused with the FNII coding sequence and expressed in Escherichia coli. The chimeric protein 6mer+FNII was purified by non-chromatographic methods. Films prepared from 6mer+FNII by solvent casting promoted only limited cell adhesion of human skin fibroblasts. However, the performance of the material in terms of cell adhesion was significantly improved when 6mer+FNII was combined with a silk-elastin-like protein in a concentration-dependent behavior. With this work we describe a novel class of biopolymer that promote cell adhesion and potentially useful as biomaterials for tissue engineering and regenerative medicine. This work reports the development of biocompatible silk-based composites with enhanced cell adhesion properties suitable for biomedical applications in regenerative medicine. The biocomposites were produced by combining a genetically engineered silk-elastin-like protein with a genetically engineered spider-silk-based polypeptide carrying the three domains of the fibronectin type II module from human metalloproteinase-2. These composites were processed into free-standing films by solvent casting and characterized for their biological behavior. To our knowledge this is the first report of the exploitation of all three FNII domains as a functional domain for the development of bioinspired materials with improved biological performance. The present study highlights the potential of using genetically engineered protein-based composites as a platform for the development of new bioinspired biomaterials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Determination of the torsion angles of alanine and glycine residues of model compounds of spider silk (AGG){sub 10} using solid-state NMR methods

Energy Technology Data Exchange (ETDEWEB)

Ashida, Jun; Ohgo, Kosuke; Komatsu, Kohei; Kubota, Ayumi; Asakura, Tetsuo [Tokyo University of Agriculture and Technology, Department of Biotechnology (Japan)], E-mail: asakura@cc.tuat.ac.jp

2003-02-15

Spiders synthesize several kinds of silk fibers. In the primary structure of spider silk, one of the major ampullate (dragline, frame) silks, spidroin 1, and flagelliform silk (core fibers of adhesive spiral), there are common repeated X-Gly-Gly (X = Ala, Leu, Pro, Tyr, Glu, and Arg) sequences, which are considered to be related to the elastic character of these fibers. In this paper, two dimensional spin diffusion solid-state NMR under off magic angle spinning (OMAS), {sup 13}C chemical shift contour plots, and Rotational Echo DOuble Resonance (REDOR) were applied to determine the torsion angles of one Ala and two kinds of Gly residues in the Ala-Gly-Gly sequence of {sup 13}C=O isotope-labeled (Ala-Gly-Gly){sub 10}. The torsion angles were determined to be ({phi}, {psi}) = (-90 deg., 150 deg.) within an experimental error of {+-}10 deg. for each residue. This conformation is characterized as 3{sub 1} helix which is in agreement with the structure proposed from the X-ray powder diffraction pattern of poly(Ala-Gly-Gly). The 3{sub 1} helix of (Ala-Gly-Gly){sub 10} does not change by formic acid treatment although (Ala-Gly){sub 15} easily changes from the silk I conformation (the structure of Bombyx mori silk fibroin before spinning in the solid state) to silk II conformation (the structure of the silk fiber after spinning) by such treatment. Thus, the 3{sub 1} helix conformation of (Ala-Gly-Gly){sub 10} is considered very stable. Furthermore, the torsion angles of the 16th Leu residue of (Leu-Gly-Gly){sub 10} were also determined as ({phi}, {psi}) = (-90 deg., 150 deg.) and this peptide is also considered to take 3{sub 1} helix conformation.

Celebrating 25 years of Syncrude`s Geotechnical Review Board

Energy Technology Data Exchange (ETDEWEB)

McKenna, G.

1998-09-01

An historical review of Syncrude`s Geotechnical Review Board (GRB) was presented, relating some of the successes of the Board over the past 25 years since its establishment. A list of the type of challenges faced by Syncrude where the GRB`s guidance and counselling proved to be critical, is also included. The GRB was established in the 1970s to help Syncrude manage its geotechnical-based risks and to enhance its long-range chances to be successful in oil sands mining. Mining oil sands was breaking new ground back then, consequently, the geotechnical risks were largely unknown and the potential of heavy financial losses were great. Under such circumstances making the right decisions in dealing with geotechnical risks was vital to success. The fact that 25 years later Syncrude is still operating on the basis of those earlier decisions and still relies heavily on the expertise of the Board for recommendations and guidance is a testimony to the value of the GRB to Syncrude`s operations. The GRB`s success is credited to the Board`s world-wide expertise, objectivity, focus on the big issues, risk-based approach and its excellent working partnership with Syncrude employees. Dragline mining and tailings management are the areas that benefited the most from the Board`s involvement, but the Board has been involved in every facet of geotechnical-based risk management. Some of the geotechnical challenges that the GRB has helped Syncrude to overcome include dam construction of muskeg foundation, heavy foundations on gassy and temperature-sensitive soils, coring and testing of gassy/expansive oil sands and haul roads, highwall design utilizing locked sands, winter construction of large fluid retaining embankments and characterization and management of fluid fine tailings. 3 refs., 1 graph, 3 figs.

Effects of local-scale decontamination in a secondary forest contaminated after the Fukushima nuclear power plant accident.

Science.gov (United States)

Ayabe, Yoshiko; Hijii, Naoki; Takenaka, Chisato

2017-09-01

We investigated whether local-scale decontamination (removal of the litter layer, superficial soil layer, and understory) in a secondary forest contaminated by the Fukushima nuclear power plant accident reduced 137 Cs contamination of the soil and litter. We also measured 137 Cs concentrations in plants and in the web-building spider Nephila clavata (Nephilidae: Arachnida), as an indicator species, to examine 137 Cs contamination in arthropods. One month after decontamination, the total 137 Cs contamination (soil + litter) was reduced by 20% (100 kBq·m -2 ) relative to that in an adjacent untreated (i.e., contaminated) area, which was however not statistically significant. Four months after decontamination, 137 Cs in the decontaminated area had increased to a level similar to those in the untreated area, and the air radiation dose in the decontaminated area was about 2.1 μSv·h -1 , significantly higher than that in the untreated area (1.9 μSv·h -1 ). This may have been attributed to a torrential rain event. Although no statistically significant reduction was observed, most spiders had a lower 137 Cs contamination than that before the decontamination. This implied that the decontamination may have reduced 137 Cs transfer from soil via litter to N. clavata through the detrital food chains, but may not have reduced the amount of 137 Cs transfer through grazing food chains because the concentration of 137 Cs in living tree leaves was not reduced by the decontamination. In autumn, about 2 kBq·m -2 of 137 Cs was supplied from foliage to the ground by litterfall. The results suggested that removal of the litter and superficial soil layers in a contaminated forest may be ineffective. The present study suggests that the local-scale decontamination in a secondary forest had no effect on the reduction of 137 Cs contamination in the treated area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oil-sands giants leaving smaller environmental footprints

International Nuclear Information System (INIS)

Stonehouse, D.

1999-01-01

Suncor Energy and Syncrude Canada are both investing billions of dollars to increase production at their mining facilities near Fort McMurray, Alberta. The two oil-sand giants will be spending a good portion of their investment (almost $1 billion) to improve their environmental performance. Both companies are focusing on reducing their energy use to cut production costs and to reduce carbon dioxide (CO 2 ) emissions. Currently, oil-sand mining accounts for the largest industrial use of electricity in Alberta. This produces tremendous amounts of greenhouse gases such as CO 2 which has been linked to global warming. By year 2006, all of Syncrude's processing equipment will be replaced by energy-efficient equipment. Shovel/truck/hydrotransport will replace the dragline/bucket-wheel/conveyor system used in the past. New technology designed to improve bitumen recovery and increase upgrading processing yields is also expected to decrease emissions by 5 million tonnes per year. Syncrude will also construct a $60 million gas turbine generator for its Aurora project. Sulphur dioxide (SO 2 ) emissions which cause acid rain, are also on the decline at both Syncrude and Suncor. Suncor will reduce its energy use through the construction of a $315 million cogeneration plant which will generate 220 MV of electricity for its operations, along with waste heat that will be used to separate the heavy oil from the sand. The cogeneration plant will be 45 per cent more efficient that current operations. Both companies have planted millions of trees and shrubs to reclaim nearly 3,000 hectares of land. The tailings from oil-sand mining are currently being captured in settling basins. Both companies have long range plans for dealing with tailings. The first is called water capping which involves layering fresh water over tailing deposits to create a lake. The second is called composite tails, which involves mixing the tailings with gypsum and sand to make them settle faster

Henretta Creek reclamation project

International Nuclear Information System (INIS)

Pumphrey, J.F.

2009-01-01

Teck Coal Ltd. operates 6 open-pit coal mines, of which 5 are located in the Elk Valley in southeastern British Columbia. The Fording River Operations (FRO) began in 1971 in mining areas in Eagle Mountain, Turnbull Mountain and Henretta Valley. The recovery of approximately 5 million tons of coal from the Henretta Creek Valley posed significant challenges to mine planners, hydrologists and environmental experts because the coal had to be recovered from the valley flanks and also from under the main valley floor, on which the fish-bearing Henretta Creek runs. The Henretta Dragline Mining project was described along with the water control structures and fisheries management efforts for the cutthroat trout. A detailed Environmental Impact Assessment and Stage 1 mining report for the Henretta Valley area was completed in December 1990. FRO was granted a mining and reclamation permit in 1991. A temporary relocation of 1,270 metres was required in in April 1997 in order to enable mining on both sides and below the creek bed. Among the innovative construction techniques was a diversion of Henretta Creek through large diameter steel culverts and a specialized crossing of the creek to allow fish passage. The first water flowed through the reclaimed Henretta Creek channel in late 1998 and the first high flow occurred in the spring of 2000. Teck coal FRO then launched an annual fish and fish habitat monitoring program which focused on the Henretta Creek Reclaimed Channel and Henretta Lake. This document presented the results from the final year, 2006, and a summary of the 7 year aquatic monitoring program. It was concluded that from mining through to reclamation, the Henretta project shows the commitment and success of mining and reclamation practices at Teck Coal. Indicators of the project's success include riparian zone vegetation, fisheries re-establishment, aquatic communities and habitat utilization by terrestrial and avian species. 33 refs., 1 fig.

Spoil pile instabilities with reference to a strip coal mine in Turkey: mechanisms and assessment of deformations

Science.gov (United States)

Kasmer, Ozgu; Ulusay, Resat; Gokceoglu, Candan

2006-02-01

With the increasing adoption of the surface mining of coal, problems associated with spoil pile instability, which affects resource recovery, mining cost, and safety and presents environmental hazards, have become a matter of prime concern to mine planners and operators. The study of geotechnical aspects is thus very important in the rational planning for the disposal, reclamation, treatment and utilization of spoil material. A strip coal mine, one of the largest open pit mines in Turkey, is located in Central Anatolia and provides coal to a thermal power station. Coal production is carried out in two adjacent open pits, the Central Pit and South Pit. A large-scale spoil pile instability over an area of 0.3 km2 occurred within the dumping area of the Central pit. In addition, small-scale movement occurred in the outside dumping area. This paper outlines the results of field and laboratory investigations to describe the mechanisms of the spoil pile instabilities and to assess deformations monitored over a long period following the failure. Shear test results indicate that the interface between the floor and spoil material dumped by dragline has a negligible cohesion and is the most critical plane of weakness for spoil pile instability. Back analyses based on the method of limit equilibrium and the numerical modelling technique, and observations in the pit revealed that failure occurred along a combined sliding surface consisting of a circular surface through the spoil material itself and a planar surface passing along the interface between the spoil piles and floor. The analyses also indicated that pore water pressure ratios of about 0.25 satisfy limiting equilibrium condition and that rainfall about one month before the failure may be a contributing factor to the instability. Movement monitoring data obtained following the failure over a 1.5-year period suggested that the ongoing deformations were mainly due to compaction of the spoil material. Based on the

A systematic reassessment and paleogeographic review of fossil xenarthra from Peru

Directory of Open Access Journals (Sweden)

2004-01-01

Full Text Available La révision des Xénarthres péruviens ainsi que la découverte de nouveaux spécimens permet d’étendre la connaissance de cet ordre sur ce territoire. Une trentaine de sites de la forêt amazonienne, des Andes et de la Côte ont révélé la présence de Xénarthres au Pérou. Thalassocnus, du mio-pliocène de la Formation Pisco, est le seul Xénarthre pré-pléistocène bien connu. Les Phyllophaga (Megatheriidae, Nothrotheriidae, Mylodontidae et Megalonychidae et les Cingulata (Pampatheriidae et Glyptodontidae pléistocènes sont rares dans la forêt amazonienne, mais sont abondants sur la côte et extrêmement fréquents dans les Andes (entre 2 500 et 4 500 mètres d’altitude. Les Cingulata sont faiblement diversifiés et représentés uniquement sur la côte par Holmesina cf. paulacoutoi et dans les Andes par Glyptodon clavipes. Le mylodontide Glossotherium sp. est reconnu sur l’ensemble de la côte péruvienne alors que le scelidotheriine Scelidodon chiliensis est abondant dans les Andes ainsi que sur la côte nord. Les nothrotheridés pléistocènes sont uniquement localisés en forêt amazonienne (Nothropus priscus de Río Acre. Les Megatheriidae sont géographiquement particulièrement bien représentés et diversifiés. Le taxon tropical Eremotherium (E. laurillardi est présent sur la côte nord et peut-être également par une forme de grande taille en Amazonie. Le genre tempéré Megatherium est représenté au Pérou par une lignée andine présentant des formes de petite taille, quadrupèdes et plutôt brouteuses (Megatherium (Pseudomegatherium. Cette lignée regroupe M. (P. tarijense, M. (P. elenense, M. (P. urbinai ainsi qu’une espèce inédite du nord des Andes. Les taxons de grande taille tels que Megatherium (Megatherium americanum, Lestodon sp. et Scelidotherium leptocephalum, typiques des vastes pampas d’Argentine, sont absents au Pérou. Un nouveau mégalonychidé très particulier vient d’être découvert sur la c

Development of a catchment/landscape erosion prediction model (MINErosion 4) for post-mining landscapes in Central Queensland, Australia.

Science.gov (United States)

Khalifa, Ashraf; Yu, Bofu; Ghadiri, Hossain; Carroll, Chris; So, Hwat-Bing

2010-05-01

Open-cut coal mining in Central Queensland involves the breaking up of overburden that overlies the coal seams using explosives, followed by removal with draglines which results in the formation of extensive overburden spoil-piles with steep slopes at the angle of repose (approximately 75 % or 37o). These spoil-piles are found in long multiple rows, with heights of up to 60 or 70 m above the original landscapes. They are generally highly saline and dispersive and hence highly erosive. Legislation requires that these spoil-piles be rehabilitated into a stable self sustaining ecosystem with no off-site pollution. The first stage in the rehabilitation of these landscapes is the lowering of slopes to create a landscape that is stable against geotechnical failure and erosion. This is followed by revegetation generally with grasses as pioneer vegetation to further reduce erosion and a mixture of native shrubs and trees. Minimizing erosion and excessive on-site discharges of sediment into the working areas may result in the temporary cessation of mining operation with significant financial consequences, while off site discharges may breach the mining lease conditions. The average cost of rehabilitation is approximately 22,000 per ha. With more than 50,000 ha of such spoil-piles in Queensland at present, the total cost of rehabilitation facing the industry is very high. Most of this comprised the cost of reshaping the landscape, largely associated with the amount of material movement necessary to achieve the desired landscape. Since soil and spoil-piles vary greatly in their erodibilities, a hillslope erosion model MINErosion 3 (this conference) was developed to determine a cost effective combination of slope length, slope gradient and vegetation that will result in acceptable rates of erosion. This model was useful to determine the design parameters for the construction of a suitable post-mining landscape that meets the required erosion criteria. However, the mining

Geology and mining history of the Southeast Missouri Barite District and the Valles Mines, Washington, Jefferson, and St. Francois Counties, Missouri

Science.gov (United States)

Mugel, Douglas N.

2017-03-09

��s draglines and front-end loaders) to mine the residuum. The ore was loaded onto rail cars (and by the 1940’s, trucks) for shipment to washer plants. Clay was removed from the barite using a log washer, and a jig was used to concentrate the barite. Overflow from the log washers was waste and went to a mud (tailings) pond. The coarse jig tailings went to tailings piles or were used as railroad ballast and, later, to create roads within the mine pit. Some barite was ground, depending on its final use, and some ground barite was bleached using a hot solution of sulfuric acid to remove impurities such as iron minerals and lead sulfide (galena). An earlier bleaching process used lead-lined tanks.Large quantities of water were required for milling the barite; some was recirculated water and the remainder came from dammed streams or was pumped from wells. Tailings and wastewater were impounded behind dikes that were built across small valleys and were increased in height as necessary using washer waste and any overburden that had been stripped. In some cases, dikes were built across valleys that had already been mined for barite.The total production of barite from the Southeast Missouri Barite District and the Valles Mines is estimated to have been about 13.1 million tons. Most of the barite production was from Washington County. Hand mining and processing of barite was inefficient. Estimates of barite recovery range from less than one-fourth to about one-half because pillars between the shafts in the residuum needed to be left unmined for stability. With mechanized mining, large amounts of barite were lost during the milling process. It has been estimated that about 30 percent of the barite was lost and that about two-thirds of the lost barite was fine-grained and was discharged to the tailings ponds. Some galena was lost to the tailings ponds.A 1972 inventory of tailings ponds by the Missouri Geological Survey identified 67 ponds in the Southeast Missouri Barite District (there

Programa de Pós-Graduação em Geologia - Dissertações Defendidas 1999 - Mestrado - Instituto de Geociências - Universidade Federal do Rio de Janeiro

Directory of Open Access Journals (Sweden)

1999-01-01

ção humana, face as variáveis ambientais reinantes na área de estudo.. Nome: Kleberson de Oliveira Porpino Orientador: Lílian Paglarelli Bergqvist Título: Estudo dos Cingulata (Xenarthra, Mammalia Fósseis Depositados no Museu Câmara Cascudo, Natal - RN Resumo: A ordem Cingulata, característica da América do Sul, é bem representada nos depósitos pleistocênicos do Brasil, onde ocorrem formas edêmicas em associação à outras cuja distribuição geográfica não se restringe ao território brasileiro. Neste trabalho efetua-se um estudo e revisão do material atribuído à ordem Cingulata e depositado no acervo do Museu Câmara Cascudo. Os fósseis foram coletados em depósitos do tipo “tanque” e em grutas calcárias, nas localidades de Lagoa do Santo, Lágea Formosa e Lajedo da Escada, situadas, respectivamente, nos municípios de Currais Novos, São Rafael e Baraúnas, no estado do Rio Grande do Norte. As peças incluem diversos osteodermos e fragmentos de carapaça bem como material pós-craniano endoesquelético diverso. A partir deste estudo identificam-se dois gêneros e três espécies: Propraopus sp., Panochthus sp., Panochthus greslebini, Panochthus jaguaribensis e Glyptodon clavipes. A presença do gênero Propraopus, cujos registros no Brasil até então limitam-se principalmente ao sudeste e sul do país, constitui a primeira ocorrên- 110 Anuário do Instituto de Geociências - UFRJ Volume 22 / 1999 cia do táxon no nordeste brasileiro. A morfologia observada no material pertencente a P. greslebini, P. jaguaribensis e G. clavipes é compatível com o que se conhece a respeito destas espécies. Ossos ainda não descritos para as duas primeiras espécies foram encontrados dentre os fósseis estudados, ampliando o conhecimento morfológico dos Panochthini do nordeste brasileiro. Diversas características morfométricas e anatômicas das peças atribuídas a Propraopus sp. apontam para a possibilidade de tratar-se de uma espécie distinta daquelas at