Science.gov

Sample records for acid building blocks

  1. Efficient ytterbium triflate catalyzed microwave-assisted synthesis of 3-acylacrylic acid building blocks.

    PubMed

    Tolstoluzhsky, Nikita V; Gorobets, Nikolay Yu; Kolos, Nadezhda N; Desenko, Sergey M

    2008-01-01

    The derivatives of 4-(hetero)aryl-4-oxobut-2-enoic acid are useful as building blocks in the synthesis of biologically active compounds. An efficient general protocol for the synthesis of these building blocks was developed. This method combines microwave assistance and ytterbium triflate catalyst and allows the fast preparation of the target acids starting from different (hetero)aromatic ketones and glyoxylic acid monohydrate giving pure products in 52-75% isolated yields.

  2. Arjunolic acid: A promising new building block for nanochemistry

    NASA Astrophysics Data System (ADS)

    Bag, Braja G.; Maity, Gopal C.; Pramanik, Subhash R.

    2005-11-01

    Arjunolic acid, the major extractable constituent of the heavy wood of textit{Terminalia Arjuna}, has the potential to be used as a rigid and functional molecular framework for the construction of nanosized supramolecular architectures and nanomaterials. The nanosized triterpenoid, arjunolic acid, showed efficient gelation of various organic solvents at low concentrations. The low molecular mass gelator molecules self-assembled in the solvents to form fibers of nanometer diameters. The movement of the solvent molecules was hindered inside the fibrous network leading to the formation of a gel.

  3. Building Minds by Block Building.

    ERIC Educational Resources Information Center

    Montopoli, Linda

    Noting that the process of playing with blocks supports the groundwork for learning in every area of a child's growth, this paper discusses specific uses of building blocks in the early childhood curriculum to develop a child's physical, social, emotional, artistic, language, scientific and mathematics growth. The paper outlines the contributions…

  4. Microbiologically produced carboxylic acids used as building blocks in organic synthesis.

    PubMed

    Aurich, Andreas; Specht, Robert; Müller, Roland A; Stottmeister, Ulrich; Yovkova, Venelina; Otto, Christina; Holz, Martina; Barth, Gerold; Heretsch, Philipp; Thomas, Franziska A; Sicker, Dieter; Giannis, Athanassios

    2012-01-01

    Oxo- and hydroxy-carboxylic acids are of special interest in organic synthesis. However, their introduction by chemical reactions tends to be troublesome especially with regard to stereoselectivity. We describe herein the biotechnological preparation of selected oxo- and hydroxycarboxylic acids under "green" conditions and their use as promising new building blocks. Thereby, our biotechnological goal was the development of process fundamentals regarding the variable use of renewable raw materials, the development of a multi purpose bioreactor and application of a pilot plant with standard equipment for organic acid production to minimize the technological effort. Furthermore the development of new product isolation procedures, with the aim of direct product recovery, capture of products or single step operation, was necessary. The application of robust and approved microorganisms, also genetically modified, capable of using a wide range of substrates as well as producing a large spectrum of products, was of special importance. Microbiologically produced acids, like 2-oxo-glutaric acid and 2-oxo-D-gluconic acid, are useful educts for the chemical synthesis of hydrophilic triazines, spiro-connected heterocycles, benzotriazines, and pyranoic amino acids. The chiral intermediate of the tricarboxylic acid cycle, (2R,3S)-isocitric acid, is another promising compound. For the first time our process provides large quantities of enantiopure trimethyl (2R,3S)-isocitrate which was used in subsequent chemical transformations to provide new chiral entities for further usage in total synthesis and pharmaceutical research.Oxo- and hydroxy-carboxylic acids are of special interest in organic synthesis. However, their introduction by chemical reactions tends to be troublesome especially with regard to stereoselectivity. We describe herein the biotechnological preparation of selected oxo- and hydroxycarboxylic acids under "green" conditions and their use as promising new building

  5. Nucleic acids and smart materials: advanced building blocks for logic systems.

    PubMed

    Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2014-09-03

    Logic gates can convert input signals into a defined output signal, which is the fundamental basis of computing. Inspired by molecular switching from one state to another under an external stimulus, molecular logic gates are explored extensively and recognized as an alternative to traditional silicon-based computing. Among various building blocks of molecular logic gates, nucleic acid attracts special attention owing to its specific recognition abilities and structural features. Functional materials with unique physical and chemical properties offer significant advantages and are used in many fields. The integration of nucleic acids and functional materials is expected to bring about several new phenomena. In this Progress Report, recent progress in the construction of logic gates by combining the properties of a range of smart materials with nucleic acids is introduced. According to the structural characteristics and composition, functional materials are categorized into three classes: polymers, noble-metal nanomaterials, and inorganic nanomaterials. Furthermore, the unsolved problems and future challenges in the construction of logic gates are discussed. It is hoped that broader interests in introducing new smart materials into the field are inspired and tangible applications for these constructs are found.

  6. Undecylenic acid: a valuable and physiologically active renewable building block from castor oil.

    PubMed

    Van der Steen, Marijke; Stevens, Christian V

    2009-01-01

    A lot of attention is currently being paid to the transition to a biobased economy. In this movement, most efforts concentrate on the development of bioenergy applications including bioethanol, biodiesel, thermochemical conversion of biomass, and others. However, in the energy sector other nonbiomass alternatives are known, whereas no valuable alternatives are available when thinking about chemical building blocks. Therefore, it is also essential to develop new routes for the synthesis of bio-based chemicals and materials derived thereof. Such intermediates can originate either from plants or from animals. Castor oil is a non-edible oil extracted from the seeds of the castor bean plant Ricinus communis (Euphorbiaceae), which grows in tropical and subtropical areas. Globally, around one million tons of castor seeds are produced every year, the leading producing areas being India, PR China, and Brazil.2 10-Undecenoic acid or undecylenic acid is a fatty acid derived from castor oil that, owing to its bifunctional nature, has many possibilities to develop sustainable applications.

  7. White biotechnology for green chemistry: fermentative 2-oxocarboxylic acids as novel building blocks for subsequent chemical syntheses.

    PubMed

    Stottmeister, U; Aurich, A; Wilde, H; Andersch, J; Schmidt, S; Sicker, D

    2005-12-01

    Functionalized compounds, which are difficult to produce by classical chemical synthesis, are of special interest as biotechnologically available targets. They represent useful building blocks for subsequent organic syntheses, wherein they can undergo stereoselective or regioselective reactions. "White Biotechnology" (as defined by the European Chemical Industry [ http://www.europabio.org/white_biotech.htm ], as part of a sustainable "Green Chemistry,") supports new applications of chemicals produced via biotechnology. Environmental aspects of this interdisciplinary combination include: Use of renewable feedstock Optimization of biotechnological processes by means of: New "high performance" microorganisms On-line measurement of substrates and products in bioreactors Alternative product isolation, resulting in higher yields, and lower energy demand In this overview we describe biotechnologically produced pyruvic, 2-oxopentaric and 2-oxohexaric acids as promising new building blocks for synthetic chemistry. In the first part, the microbial formation of 2-oxocarboxylic acids (2-OCAs) in general, and optimization of the fermentation steps required to form pyruvic acid, 2-oxoglutaric acid, and 2-oxo-D-gluconic acid are described, highlighting the fundamental advantages in comparison to chemical syntheses. In the second part, a set of chemical formula schemes demonstrate that 2-OCAs are applicable as building blocks in the chemical synthesis of, e.g., hydrophilic triazines, spiro-connected heterocycles, benzotriazines, and pyranoic amino acids. Finally, some perspectives are discussed.

  8. Fmoc-modified amino acids and short peptides: simple bio-inspired building blocks for the fabrication of functional materials.

    PubMed

    Tao, Kai; Levin, Aviad; Adler-Abramovich, Lihi; Gazit, Ehud

    2016-07-11

    Amino acids and short peptides modified with the 9-fluorenylmethyloxycarbonyl (Fmoc) group possess eminent self-assembly features and show distinct potential for applications due to the inherent hydrophobicity and aromaticity of the Fmoc moiety which can promote the association of building blocks. Given the extensive study and numerous publications in this field, it is necessary to summarize the recent progress concerning these important bio-inspired building blocks. Therefore, in this review, we explore the self-organization of this class of functional molecules from three aspects, i.e., Fmoc-modified individual amino acids, Fmoc-modified di- and tripeptides, and Fmoc-modified tetra- and pentapeptides. The relevant properties and applications related to cell cultivation, bio-templating, optical, drug delivery, catalytic, therapeutic and antibiotic properties are subsequently summarized. Finally, some existing questions impeding the development of Fmoc-modified simple biomolecules are discussed, and corresponding strategies and outlooks are suggested.

  9. The Building Blocks of Geology.

    ERIC Educational Resources Information Center

    Gibson, Betty O.

    2001-01-01

    Discusses teaching techniques for teaching about rocks, minerals, and the differences between them. Presents a model-building activity that uses plastic building blocks to build crystal and rock models. (YDS)

  10. Design and synthesis of an Fmoc-SPPS-compatible amino acid building block mimicking the transition state of phosphohistidine phosphatase.

    PubMed

    Eerland, Martijn F; Hedberg, Christian

    2012-02-17

    The synthesis of a sulfonamide-based transition-state (TS) analogue of enzymatic phosphohistidine dephosphorylation as an amino acid building block is presented, together with the proof-of-concept of its incorporation into peptides. Key features include final global acidolytic protective group removal as well as full compatibility with standard Fmoc solid-phase peptide synthesis (SPPS). The peptides are designed as inhibitors of phosphohistidine phosphatase and as a pull-down probe for identification of phosphohistidine phosphatases, respectively.

  11. Solar power building block

    SciTech Connect

    Charlton, W.T.

    1982-04-20

    A building unit for exterior walls and the like comprising a molded block of glass having a recess in the side face which is to face the exterior, the recess having a side wall and an open outer end on which a fresnel lens is disposed, the inner end of the recess having a solar cell disposed therein so that sunlight passing through the fresnel lens impinges on the solar cell for the generation of electric power together with a battery disposed within a cavity molded in the block connected by a circuit to the solar cell for storing the generated electric power for subsequent use as needed in a residence or the like. A further embodiment has attached to the interior wall a black painted duct containing vertical radiant fins. This unit contains a ''window'' through which the concentrated radiation is directed by the lens arrangement of the side walls and front lens to create a highly energetic radiant impingement upon the black duct heating it. Air flowing vertically in the duct is used for heating of interior air or removal of superheated interior air by using the force of the rising air for an '' air cooling'' effect.

  12. Synthesis of enantiopure trifluoromethyl building blocks via a highly chemo- and diastereoselective nucleophilic trifluoromethylation of tartaric acid-derived diketones.

    PubMed

    Massicot, Fabien; Monnier-Benoit, Nicolas; Deka, Naba; Plantier-Royon, Richard; Portella, Charles

    2007-02-16

    A highly diastereoselective nucleophilic mono(trifluoromethylation) of a tartaric acid-based diketone, using trifluoromethyl(trimethyl)silane, afforded the corresponding gamma-keto trifluoromethylcarbinol. The scope and limitation of this reaction was studied. The acidic removal of the acetonide moiety protecting the two hydroxyl groups of the adducts was unsuccessful. Bis(O-methylation) of the aromatic derivatives under basic conditions, followed by acidic hydrolysis and oxidative cleavage, led to two different enantiopure products: an alpha-aryl-alpha-methoxy-alpha-trifluoromethyl ethanal and an alpha-aryl-alpha-methoxycarboxylic acid. The overall process is eventually an interesting way to convert one natural chiral raw material into two functionalized enantiopure building blocks including a trifluoromethyl one.

  13. Building Curriculum during Block Play

    ERIC Educational Resources Information Center

    Andrews, Nicole

    2015-01-01

    Blocks are not just for play! In this article, Nicole Andrews describes observing the interactions of three young boys enthusiastically engaged in the kindergarten block center of their classroom, using blocks in a building project that displayed their ability to use critical thinking skills, physics exploration, and the development of language…

  14. Biopolymers Containing Unnatural Building Blocks

    SciTech Connect

    Schultz, Peter G.

    2013-06-30

    Although the main chain structure of polymers has a profound effect on their materials properties, the side groups can also have dramatic effects on their properties including conductivity, liquid crystallinity, hydrophobicity, elasticity and biodegradability. Unfortunately control over the side chain structure of polymers remains a challenge – it is difficult to control the sequence of chain elongation when mixtures of monomers are polymerized, and postpolymerization side chain modification is made difficult by polymer effects on side chain reactivity. In contrast, the mRNA templated synthesis of polypeptides on the ribosome affords absolute control over the primary sequence of the twenty amino acid monomers. Moreover, the length of the biopolymer is precisely controlled as are sites of crosslinking. However, whereas synthetic polymers can be synthesized from monomers with a wide range of chemically defined structures, ribosomal biosynthesis is largely limited to the 20 canonical amino acids. For many applications in material sciences, additional building blocks would be desirable, for example, amino acids containing metallocene, photoactive, and halogenated side chains. To overcome this natural constraint we have developed a method that allows unnatural amino acids, beyond the common twenty, to be genetically encoded in response to nonsense or frameshift codons in bacteria, yeast and mammalian cells with high fidelity and good yields. Here we have developed methods that allow identical or distinct noncanonical amino acids to be incorporated at multiple sites in a polypeptide chain, potentially leading to a new class of templated biopolymers. We have also developed improved methods for genetically encoding unnatural amino acids. In addition, we have genetically encoded new amino acids with novel physical and chemical properties that allow selective modification of proteins with synthetic agents. Finally, we have evolved new metal-ion binding sites in proteins

  15. Building Blocks for Personal Brands

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2011-01-01

    In this article, the author discusses the four essential building blocks for personal brands: (1) name; (2) message; (3) channels; and (4) bridges. However, outstanding building materials can only take a person so far. The author emphasizes that vision, determination, faith, a sense of humor, and humility are also required.

  16. Caesium fluoride-promoted Stille coupling reaction: an efficient synthesis of 9Z-retinoic acid and its analogues using a practical building block.

    PubMed

    Okitsu, Takashi; Iwatsuka, Kinya; Wada, Akimori

    2008-12-21

    A highly efficient and rapid total synthesis of 9Z-retinoic acid was accomplished by caesium fluoride-promoted Stille coupling reaction; using a common building block, 9Z-retinoic acid analogues were also prepared by the same method without isomerisation of the Z-double bond.

  17. C-3 epimers of sugar amino acids as foldameric building blocks: improved synthesis, useful derivatives, coupling strategies.

    PubMed

    Nagy, Adrienn; Csordás, Barbara; Zsoldos-Mády, Virág; Pintér, István; Farkas, Viktor; Perczel, András

    2017-02-01

    To obtain key sugar derivatives for making homooligomeric foldamers or α/β-chimera peptides, economic and multigram scale synthetic methods were to be developed. Though described in the literature, the cost-effective making of both 3-amino-3-deoxy-ribofuranuronic acid (H-t X-OH) and its C-3 epimeric stereoisomer, the 3-amino-3-deoxy-xylofuranuronic acid (H-c X-OH) from D-glucose is described here. The present synthetic route elaborated is (1) appropriate for large-scale synthesis; (2) reagent costs reduced (e.g. by a factor of 400); (3) yields optimized are ~80% or higher for all six consecutive steps concluding -t X- or -c X- and (4) reaction times shortened. Thus, a new synthetic route step-by-step optimized for yield, cost, time and purification is given both for D-xylo and D-ribo-amino-furanuronic acids using sustainable chemistry (e.g. less chromatography with organic solvents; using continuous-flow reactor). Our study encompasses necessary building blocks (e.g. -X-OMe, -X-O(i)Pr, -X-NHMe, Fmoc-X-OH) and key coupling reactions making -Aaa-t X-Aaa- or -Aaa-t X-t X-Aaa- type "inserts". Completed for both stereoisomers of X, including the newly synthesized Fmoc-c X-OH, producing longer oligomers for drug design and discovery is more of a reality than a wish.

  18. Formamide as the main building block in the origin of nucleic acids.

    PubMed

    Costanzo, Giovanna; Saladino, Raffaele; Crestini, Claudia; Ciciriello, Fabiana; Di Mauro, Ernesto

    2007-08-16

    The simplest molecules grouping the four most common elements of the universe H,C,O and N (with the exception of the biologically inert He) are isocyanate HNCO and formamide H2NCOH. Reasons for the availability of formamide on prebiotic Earth are presented. We review evidence showing that formamide in the presence of largely available catalysts and by moderate heating yields the complete set of nucleic bases necessary for the formation of nucleic acids. Formamide also favours the formation of acyclonucleosides and the phosphorylation and trans-phosphorylation of nucleosides, thus providing a plausible chemical frame for the passage from a simple one-carbon compound to nucleic polymers. Physico-chemical conditions exist in which formamide favours the stability of the phosphoester bonds in nucleic polymers relative to that of the same bonds in monomers. Starting from a formamide-laden environment subject only to the laws of chemistry, a hypothesis is outlined sketching the passage towards an aqueous world in which Darwinian rules apply.

  19. EcdGHK are Three Tailoring Iron Oxygenases for Amino Acid Building Blocks of the Echinocandin Scaffold

    PubMed Central

    Jiang, Wei; Cacho, Ralph A; Chiou, Grace; Garg, Neil K; Tang, Yi; Walsh, Christopher T

    2013-01-01

    The echinocandins are a small group of fungal N-acylated cyclic hexapeptides that are fungicidal for candida strains and fungistatic for aspergilli by targeting cell wall 1,3-β-glucan synthases. The side chains of all six amino acid building blocks have hydroxyl groups, including the nonproteinogenic 4R,5R-dihydroxy-Orn1, 4R-OH-Pro3, 3S, 4S-dihydroxy-homoTyr4 and 3S-OH-4S-Me-Pro6. The echinocandin (ecd) gene cluster contains two predicted nonheme mononuclear iron oxygenase genes (ecdG,K) and one encoding a P450 type heme protein (ecdH). Deletion of the ecdH gene in the producing Emericella rugulosa generates an echinocandin scaffold (echinocandin D) lacking both hydroxyl groups on Orn1. Correspondingly, the ΔecdG strain failed to hydroxylate C3 of the homoTyr residue, and purified EcdG hydroxylated free L-homoTyr at C3. The ΔecdK strain failed to generate mature echinocandin unless supplemented with either 4R-Me-Pro or 3S-OH-4S-Me-Pro, indicating blockage of a step upstream of Me-Pro formation. Purified EcdK is a Leu 5-hydroxylase, acting iteratively at C5 to yield γ-Me-Glu-γ-semialdehyde in equilibrium with the cyclic imine product. Evaluation of deshydroxyechinocandin scaffolds in in vitro anticandidal assays revealed up to 3-fold loss of potency for the ΔecdG scaffolds, but a 3-fold gain of potency for the ΔecdH scaffold, in line with prior results on deoxyechinocandin homologs. PMID:23451921

  20. Polymeric assembly of hyperbranched building blocks to establish tunable nanoplatforms for lysosome acidity-responsive gene/drug co-delivery.

    PubMed

    Jia, Hui-Zhen; Zhang, Wei; Wang, Xu-Li; Yang, Bin; Chen, Wei-Hai; Chen, Si; Chen, Gang; Zhao, Yi-Fang; Zhuo, Ren-Xi; Feng, Jun; Zhang, Xian-Zheng

    2015-07-01

    This study plans to develop a nanoparticle technology that can assemble different polymeric "building blocks" with various desired functionalities into one nanosystem in a pH-dependent manner. For this purpose, polymeric building blocks were specifically designed with hyperbranched architectures, and orthogonal pH-reversible phenylboronic acid-diols were taken as "joints" to integrate them together. To verify the idea, a corona-core dual-polymer nanoassembly was prepared as the vehicle for lysosomotropic gene/drug co-delivery. Phenylboronic acid modified hyperbranched oligoethylenimine (OEI-PBA) was arranged to cluster around the hydrophobic core composed of hyperbranched polyglycerol, just by mixing two polymers in an appropriate ratio at neutral conditions. Compared with the parent OEI-PBA, this nanoassembly demonstrated better capture of plasmid DNA, highly enhanced activity for cellular transport and gene transfection (up to 100 fold), the ability to further load hydrophobic drugs, lysosome acidity-targeting pH-dependent release of both carried cargoes, and improved cell-biocompatibility. To evaluate its potential for combinational gene/drug therapy, in vitro experiments using the therapeutic p53 gene and antitumor doxorubicin as models were carried out. This intracellular co-delivery led to apparently synergetic anti-cancer effects in cultured cancer cells. This dynamic paradigm shows interesting features including easy manipulation, reversible conjugation, lysosome-targeting pH-responsiveness, high co-delivery efficiency, and functional expandability by further accommodating other building blocks.

  1. Hydrophilic interaction chromatography-multiple reaction monitoring mass spectrometry method for basic building block analysis of low molecular weight heparins prepared through nitrous acid depolymerization.

    PubMed

    Sun, Xiaojun; Guo, Zhimou; Yu, Mengqi; Lin, Chao; Sheng, Anran; Wang, Zhiyu; Linhardt, Robert J; Chi, Lianli

    2017-01-06

    Low molecular weight heparins (LMWHs) are important anticoagulant drugs that are prepared through depolymerization of unfractionated heparin. Based on the types of processing reactions and the structures of the products, LMWHs can be divided into different classifications. Enoxaparin is prepared by benzyl esterification and alkaline depolymerization, while dalteparin and nadroparin are prepared through nitrous acid depolymerization followed by borohydride reduction. Compositional analysis of their basic building blocks is an effective way to provide structural information on heparin and LMWHs. However, most current compositional analysis methods have been limited to heparin and enoxaparin. A sensitive and comprehensive approach is needed for detailed investigation of the structure of LMWHs prepared through nitrous acid depolymerization, especially their characteristic saturated non-reducing end (NRE) and 2,5-anhydro-d-mannitol reducing end (RE). A maltose modified hydrophilic interaction column offers improved separation of complicated mixtures of acidic disaccharides and oligosaccharides. A total of 36 basic building blocks were unambiguously identified by high-resolution tandem mass spectrometry (MS). Multiple reaction monitoring (MRM) MS/MS quantification was developed and validated in the analysis of dalteparin and nadroparin samples. Each group of building blocks revealed different aspects of the properties of LMWHs, such as functional motifs required for anticoagulant activity, the structure of heparin starting materials, cleavage sites in the depolymerization reaction, and undesired structural modifications resulting from side reactions.

  2. Dynamic Covalent Nanoparticle Building Blocks

    PubMed Central

    2016-01-01

    Abstract Rational and generalisable methods for engineering surface functionality will be crucial to realising the technological potential of nanomaterials. Nanoparticle‐bound dynamic covalent exchange combines the error‐correcting and environment‐responsive features of equilibrium processes with the stability, structural precision, and vast diversity of covalent chemistry, defining a new and powerful approach for manipulating structure, function and properties at nanomaterial surfaces. Dynamic covalent nanoparticle (DCNP) building blocks thus present a whole host of possibilities for constructing adaptive systems, devices and materials that incorporate both nanoscale and molecular functional components. At the same time, DCNPs have the potential to reveal fundamental insights regarding dynamic and complex chemical systems confined to nanoscale interfaces. PMID:27312526

  3. Nanostructured particles from multi scale building blocks

    NASA Astrophysics Data System (ADS)

    Hampsey, J. Eric

    Nanotechnology has emerged as one of the most exciting new and developing fields in science today. New nanoscale materials and devices such as nanoparticles, nanocomposites, nanowires, and nanosensors could revolutionize the 21st century in the same way that the transistor and Internet led to the information age. One key component in developing these new technologies is to assemble individual atomic and molecular building blocks into larger structures with fundamentally new properties and functions. Nature is very efficient at assembling multi scale building blocks such as proteins, lipids, and minerals into nanostructured materials such as bone, teeth, diatoms, eggshells, seashells, cell membranes, and DNA. Surfactant and colloidal building block can also be assembled into different nanoscale materials and devices by utilizing hydrophobic/hydrophilic and other surface interactions. Using these concepts, this dissertation focuses on the syntheses and applications of nanostructured particles assembled from multi scale building blocks. Important factors in the synthesis of the particles include particle size, particle morphology, pore size and pore structure. Five different types of nanostructured particles assembled from different multi scale building blocks are demonstrated in this work: (1) Spherical metal/silica mesoporous particles with high surface areas and controllable pore sizes, pore structures, and metal content are synthesized from surfactant, silicate, and metal building blocks for catalytic applications; (2) Mesoporous hollow spheres with controllable pore sizes and pore structures are synthesized from surfactant, silica, and polystyrene building blocks; (3) Spherical mesoporous carbon particles with controllable pore sizes and pore structures are templated from silica particles assembled from silica and surfactant building blocks; (4) Spherical mesoporous, microporous, and bimodal carbon particles are synthesized from sucrose and silica building blocks

  4. A Self-Assembled Aggregate Composed of a Fatty Acid Membrane and the Building Blocks of Biological Polymers Provides a First Step in the Emergence of Protocells

    PubMed Central

    Black, Roy A.; Blosser, Matthew C.

    2016-01-01

    We propose that the first step in the origin of cellular life on Earth was the self-assembly of fatty acids with the building blocks of RNA and protein, resulting in a stable aggregate. This scheme provides explanations for the selection and concentration of the prebiotic components of cells; the stabilization and growth of early membranes; the catalysis of biopolymer synthesis; and the co-localization of membranes, RNA and protein. In this article, we review the evidence and rationale for the formation of the proposed aggregate: (i) the well-established phenomenon of self-assembly of fatty acids to form vesicles; (ii) our published evidence that nucleobases and sugars bind to and stabilize such vesicles; and (iii) the reasons why amino acids likely do so as well. We then explain how the conformational constraints and altered chemical environment due to binding of the components to the membrane could facilitate the formation of nucleosides, oligonucleotides and peptides. We conclude by discussing how the resulting oligomers, even if short and random, could have increased vesicle stability and growth more than their building blocks did, and how competition among these vesicles could have led to longer polymers with complex functions. PMID:27529283

  5. Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

    PubMed Central

    Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

    2011-01-01

    In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373

  6. Building blocks for subleading helicity operators

    SciTech Connect

    Kolodrubetz, Daniel W.; Moult, Ian; Stewart, Iain W.

    2016-05-24

    On-shell helicity methods provide powerful tools for determining scattering amplitudes, which have a one-to-one correspondence with leading power helicity operators in the Soft-Collinear Effective Theory (SCET) away from singular regions of phase space. We show that helicity based operators are also useful for enumerating power suppressed SCET operators, which encode subleading amplitude information about singular limits. In particular, we present a complete set of scalar helicity building blocks that are valid for constructing operators at any order in the SCET power expansion. In conclusion, we also describe an interesting angular momentum selection rule that restricts how these building blocks can be assembled.

  7. Building blocks for subleading helicity operators

    NASA Astrophysics Data System (ADS)

    Kolodrubetz, Daniel W.; Moult, Ian; Stewart, Iain W.

    2016-05-01

    On-shell helicity methods provide powerful tools for determining scattering amplitudes, which have a one-to-one correspondence with leading power helicity operators in the Soft-Collinear Effective Theory (SCET) away from singular regions of phase space. We show that helicity based operators are also useful for enumerating power suppressed SCET operators, which encode subleading amplitude information about singular limits. In particular, we present a complete set of scalar helicity building blocks that are valid for constructing operators at any order in the SCET power expansion. We also describe an interesting angular momentum selection rule that restricts how these building blocks can be assembled.

  8. Microwave spectroscopy of biomolecular building blocks.

    PubMed

    Alonso, José L; López, Juan C

    2015-01-01

    Microwave spectroscopy, considered as the most definitive gas phase structural probe, is able to distinguish between different conformational structures of a molecule, because they have unique spectroscopic constants and give rise to distinct individual rotational spectra.Previously, application of this technique was limited to molecular specimens possessing appreciable vapor pressures, thus discarding the possibility of studying many other molecules of biological importance, in particular those with high melting points, which had a tendency to undergo thermal reactions, and ultimately degradation, upon heating.Nowadays, the combination of laser ablation with Fourier transform microwave spectroscopy techniques, in supersonic jets, has enabled the gas-phase study of such systems. In this chapter, these techniques, including broadband spectroscopy, as well as results of their application into the study of the conformational panorama and structure of biomolecular building blocks, such as amino acids, nucleic bases, and monosaccharides, are briefly discussed, and with them, the tools for conformational assignation - rotational constants, nuclear quadrupole coupling interaction, and dipole moment.

  9. Conference on Building Blocks to Success.

    ERIC Educational Resources Information Center

    Ohio State Board of Education, Columbus.

    This document reproduces several papers that were delivered at the Ohio Department of Education's statewide ESEA Title I conference 1971, the theme of which was "Building Blocks to Success"; this typifies how Ohio school administrators and teachers have designed Title I programs to help educationally disadvantaged children experience…

  10. Single molecule magnets from magnetic building blocks

    NASA Astrophysics Data System (ADS)

    Kroener, W.; Paretzki, A.; Cervetti, C.; Hohloch, S.; Rauschenbach, S.; Kern, K.; Dressel, M.; Bogani, L.; M&üLler, P.

    2013-03-01

    We provide a basic set of magnetic building blocks that can be rationally assembled, similar to magnetic LEGO bricks, in order to create a huge variety of magnetic behavior. Using rare-earth centers and multipyridine ligands, fine-tuning of intra and intermolecular exchange interaction is demonstrated. We have investigated a series of molecules with monomeric, dimeric and trimeric lanthanide centers using SQUID susceptometry and Hall bar magnetometry. A home-made micro-Hall-probe magnetometer was used to measure magnetic hysteresis loops at mK temperatures and fields up to 17 T. All compounds show hysteresis below blocking temperatures of 3 to 4 K. The correlation of the assembly of the building blocks with the magnetic properties will be discussed.

  11. Pyridine-2,6-bis(monothiocarboxylic) acid and 2-aminopyridine as building blocks of a novel proton transfer compound: Solution and X-ray crystal structural studies

    NASA Astrophysics Data System (ADS)

    Moghimi, A.; Moosavi, S. M.; Kordestani, D.; Maddah, B.; Shamsipur, M.; Aghabozorg, H.; Ramezanipour, F.; Kickelbick, G.

    2007-02-01

    The synthesis of a novel proton transfer compound (2-apyH)(pdtcH), L, derived from pyridine-2,6-bis(monothiocarboxylic) acid, (pdtcH 2), is reported. This compound was prepared from the reaction between pdtcH 2, and 2-aminopyridine, (2-apy), in water as solvent. The characterization was performed using 1H and 13C solution NMR and single crystal X-ray diffraction analysis. Crystal structure analysis reveals that intra- and intermolecular proton transfer from the diacid pdtcH 2 to the base 2-apy results in the formation of a supramolecular network, which is self-assembled via non-covalent interactions. The monocationic (2-apyH) + and monoanionic (pdtcH) - building blocks are connected through H-bonding, π-π interactions and ion-pairing simultaneously as shown in the X-ray crystal structure. The monoanionic fragments are located almost parallel to each other and the cationic species have also situations nearly parallel to each other, positioning almost perpendicular to anions. The aqueous solution studies were accomplished by spectrophotometric and potentiometric pH titrations. The most abundant proton transfer species present at pH < 6 is (2-apyH)(pdtcH), in support of association between (2-apyH) + and (pdtcH) - in L, being similar to that observed by NMR spectroscopy and X-ray crystal structure analysis.

  12. Prebiotic synthesis of nucleic acids and their building blocks at the atomic level - merging models and mechanisms from advanced computations and experiments.

    PubMed

    Šponer, Judit E; Szabla, Rafał; Góra, Robert W; Saitta, A Marco; Pietrucci, Fabio; Saija, Franz; Di Mauro, Ernesto; Saladino, Raffaele; Ferus, Martin; Civiš, Svatopluk; Šponer, Jiří

    2016-07-27

    The origin of life on Earth is one of the most fascinating questions of contemporary science. Extensive research in the past decades furnished diverse experimental proposals for the emergence of first informational polymers that could form the basis of the early terrestrial life. Side by side with the experiments, the fast development of modern computational chemistry methods during the last 20 years facilitated the use of in silico modelling tools to complement the experiments. Modern computations can provide unique atomic-level insights into the structural and electronic aspects as well as the energetics of key prebiotic chemical reactions. Many of these insights are not directly obtainable from the experimental techniques and the computations are thus becoming indispensable for proper interpretation of many experiments and for qualified predictions. This review illustrates the synergy between experiment and theory in the origin of life research focusing on the prebiotic synthesis of various nucleic acid building blocks and on the self-assembly of nucleotides leading to the first functional oligonucleotides.

  13. Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

    PubMed Central

    Nörrlinger, Markus

    2014-01-01

    Summary New aromatic glycoconjugate building blocks based on the trifunctional 3-aminomethyl-5-aminobenzoic acid backbone and sugars linked to the backbone by a malonyl moiety were prepared via peptide coupling. The orthogonally protected glycoconjugates, bearing an acetyl-protected glycoside, were converted into their corresponding acids which are suitable building blocks for combinatorial glycopeptide synthesis. PMID:25383116

  14. Building blocks for subleading helicity operators

    DOE PAGES

    Kolodrubetz, Daniel W.; Moult, Ian; Stewart, Iain W.

    2016-05-24

    On-shell helicity methods provide powerful tools for determining scattering amplitudes, which have a one-to-one correspondence with leading power helicity operators in the Soft-Collinear Effective Theory (SCET) away from singular regions of phase space. We show that helicity based operators are also useful for enumerating power suppressed SCET operators, which encode subleading amplitude information about singular limits. In particular, we present a complete set of scalar helicity building blocks that are valid for constructing operators at any order in the SCET power expansion. In conclusion, we also describe an interesting angular momentum selection rule that restricts how these building blocks canmore » be assembled.« less

  15. Porous polymers based on aryleneethynylene building blocks.

    PubMed

    Bunz, Uwe H F; Seehafer, Kai; Geyer, Florian L; Bender, Markus; Braun, Ingo; Smarsly, Emanuel; Freudenberg, Jan

    2014-09-01

    Porous conjugated polymers are synthesized by metal-catalyzed coupling reactions. The progress for porous polymers when planar or tetrahedral building blocks are connected by alkyne units into novel materials is highlighted. The most prominent reaction for the buildup of the microporous alkyne-bridged polymers is the Sonogashira reaction, connecting alkynes to aromatic iodides or bromides. The availability of the building blocks and the potency of the Sonogashira reaction allow preparing a large variety of intrinsically porous polymeric materials, in which rigid struts connect multipronged centers. The microporous polymers are used as catalysts and as storage materials for gases and sensors. Postfunctionalization schemes, understanding of structure-property relationships, and the quest for high porosity are pertinent.

  16. Fast and Facile Synthesis of 4-Nitrophenyl 2-Azidoethylcarbamate Derivatives from N-Fmoc-Protected α-Amino Acids as Activated Building Blocks for Urea Moiety-Containing Compound Library.

    PubMed

    Chen, Ying-Ying; Chang, Li-Te; Chen, Hung-Wei; Yang, Chia-Ying; Hsin, Ling-Wei

    2017-03-13

    A fast and facile synthesis of a series of 4-nitrophenyl 2-azidoethylcarbamate derivatives as activated urea building blocks was developed. The N-Fmoc-protected 2-aminoethyl mesylates derived from various commercially available N-Fmoc-protected α-amino acids, including those having functionalized side chains with acid-labile protective groups, were directly transformed into 4-nitrophenyl 2-azidoethylcarbamate derivatives in 1 h via a one-pot two-step reaction. These urea building blocks were utilized for the preparation of a series of urea moiety-containing mitoxantrone-amino acid conjugates in 75-92% yields and parallel solution-phase synthesis of a urea compound library consisted of 30 members in 38-70% total yields.

  17. Routing System for Building Block Layout

    NASA Astrophysics Data System (ADS)

    Chen, Nang-Ping

    With the advent VLSI, layout techniques become more and more crucial to IC design. An automatic building block layout system is a useful tool to deal with the increasing complexity of custom chip layout problem. An approach to the routing part of this layout system is proposed. This routing system can handle arbitrarily shaped rectilinear blocks with pins on the boundary. A feature of this system is its ability to shift blocks at any moment so that better placement and hence better routing can be achieved. The system minimizes layout area and assures 100% routing completion. A relative placement is the input to this routing system. The prerouting analysis will calculate the expected routing density around each block and the routing space is allocated accordingly. The "bottleneck" idea is introduced to represent the critical regions of the layout plane where the congestion of routing is most likely to occur. It also serves as a link between blocks whereby all information are easily updated when some blocks have to move their positions. A weighted "global routing graph" is constructed to reflect the current routing situation associated with bottlenecks. The global routing of each signal is done by a "Steiner-Tree-on-Graphs" (STOG) algorithm. The basic element of STOG is a three-point Steiner-Tree-on-Graphs algorithm. Some theoretical results are derived and an efficient algorithm is developed based on them. STOG has reasonable computational complexities and yields very good results from experimental tests. In the detailed routing phase, an existing channel router and a switch-box router are called for track assignment. Special emphasis has been put on terminal position alignment between two neighboring channels to avoid unnecessary jogs. The power and ground will be allowed different wire width and routed on the metal layer. Several examples have been tested against this routing system. It has achieved very compact layout in short running time.

  18. A building block for hardware belief networks

    PubMed Central

    Behin-Aein, Behtash; Diep, Vinh; Datta, Supriyo

    2016-01-01

    Belief networks represent a powerful approach to problems involving probabilistic inference, but much of the work in this area is software based utilizing standard deterministic hardware based on the transistor which provides the gain and directionality needed to interconnect billions of them into useful networks. This paper proposes a transistor like device that could provide an analogous building block for probabilistic networks. We present two proof-of-concept examples of belief networks, one reciprocal and one non-reciprocal, implemented using the proposed device which is simulated using experimentally benchmarked models. PMID:27443521

  19. Building blocks for correlated superconductors and magnets

    DOE PAGES

    Sarrao, J. L.; Ronning, F.; Bauer, E. D.; ...

    2015-04-01

    Recent efforts at Los Alamos to discover strongly correlated superconductors and hard ferromagnets are reviewed. While serendipity remains a principal engine of materials discovery, design principles and structural building blocks are beginning to emerge that hold potential for predictive discovery. Successes over the last decade with the so-called “115” strongly correlated superconductors are summarized, and more recent efforts to translate these insights and principles to novel hard magnets are discussed. While true “materials by design” remains a distant aspiration, progress is being made in coupling empirical design principles to electronic structure simulation to accelerate and guide materials design and synthesis.

  20. Birth of a nanoscience building block.

    PubMed

    Alivisatos, A Paul

    2008-08-01

    The first Kavli Prize in Nanoscience has recognized two giants of the field, Louis Brus and Sumio Ijima, who have helped to lay the foundation of the field of nanoscience through their efforts to develop two of the most fundamental nanoscience building blocks: colloidal quantum dots and the carbon nanotube. In this Focus, I provide a brief history on the birth of the field of semiconductor nanoparticles, or quantum dots, and outline the contributions that Louis Brus has made in this area, which have served to advance the field of nanoscience in vast and far-reaching ways.

  1. Hydration effects on the electronic properties of eumelanin building blocks

    NASA Astrophysics Data System (ADS)

    Assis Oliveira, Leonardo Bruno; L. Fonseca, Tertius; Costa Cabral, Benedito J.; Coutinho, Kaline; Canuto, Sylvio

    2016-08-01

    Theoretical results for the electronic properties of eumelanin building blocks in the gas phase and water are presented. The building blocks presently investigated include the monomeric species DHI (5,6-dihydroxyindole) or hydroquinone (HQ), DHICA (5,6-dihydroxyindole-2-carboxylic acid), indolequinone (IQ), quinone methide (MQ), two covalently bonded dimers [HM ≡ HQ + MQ and IM ≡ IQ + MQ], and two tetramers [HMIM ≡ HQ + IM, IMIM ≡ IM + IM]. The electronic properties in water were determined by carrying out sequential Monte Carlo/time dependent density functional theory calculations. The results illustrate the role played by hydrogen bonding and electrostatic interactions in the electronic properties of eumelanin building blocks in a polar environment. In water, the dipole moments of monomeric species are significantly increased ([54-79]%) relative to their gas phase values. Recently, it has been proposed that the observed enhancement of the higher-energy absorption intensity in eumelanin can be explained by excitonic coupling among eumelanin protomolecules [C.-T. Chen et al., Nat. Commun. 5, 3859 (2014)]. Here, we are providing evidence that for DHICA, IQ, and HMIM, the electronic absorption toward the higher-energy end of the spectrum ([180-220] nm) is enhanced by long-range Coulombic interactions with the water environment. It was verified that by superposing the absorption spectra of different eumelanin building blocks corresponding to the monomers, dimers, and tetramers in liquid water, the behaviour of the experimental spectrum, which is characterised by a nearly monotonic decay from the ultraviolet to the infrared, is qualitatively reproduced. This result is in keeping with a "chemical disorder model," where the broadband absorption of eumelanin pigments is determined by the superposition of the spectra associated with the monomeric and oligomeric building blocks.

  2. Hydration effects on the electronic properties of eumelanin building blocks.

    PubMed

    Assis Oliveira, Leonardo Bruno; L Fonseca, Tertius; Costa Cabral, Benedito J; Coutinho, Kaline; Canuto, Sylvio

    2016-08-28

    Theoretical results for the electronic properties of eumelanin building blocks in the gas phase and water are presented. The building blocks presently investigated include the monomeric species DHI (5,6-dihydroxyindole) or hydroquinone (HQ), DHICA (5,6-dihydroxyindole-2-carboxylic acid), indolequinone (IQ), quinone methide (MQ), two covalently bonded dimers [HM ≡ HQ + MQ and IM ≡ IQ + MQ], and two tetramers [HMIM ≡ HQ + IM, IMIM ≡ IM + IM]. The electronic properties in water were determined by carrying out sequential Monte Carlo/time dependent density functional theory calculations. The results illustrate the role played by hydrogen bonding and electrostatic interactions in the electronic properties of eumelanin building blocks in a polar environment. In water, the dipole moments of monomeric species are significantly increased ([54-79]%) relative to their gas phase values. Recently, it has been proposed that the observed enhancement of the higher-energy absorption intensity in eumelanin can be explained by excitonic coupling among eumelanin protomolecules [C.-T. Chen et al., Nat. Commun. 5, 3859 (2014)]. Here, we are providing evidence that for DHICA, IQ, and HMIM, the electronic absorption toward the higher-energy end of the spectrum ([180-220] nm) is enhanced by long-range Coulombic interactions with the water environment. It was verified that by superposing the absorption spectra of different eumelanin building blocks corresponding to the monomers, dimers, and tetramers in liquid water, the behaviour of the experimental spectrum, which is characterised by a nearly monotonic decay from the ultraviolet to the infrared, is qualitatively reproduced. This result is in keeping with a "chemical disorder model," where the broadband absorption of eumelanin pigments is determined by the superposition of the spectra associated with the monomeric and oligomeric building blocks.

  3. The Cellular Building Blocks of Breathing

    PubMed Central

    Ramirez, J.M.; Doi, A.; Garcia, A.J.; Elsen, F.P.; Koch, H.; Wei, A.D.

    2013-01-01

    Respiratory brainstem neurons fulfill critical roles in controlling breathing: they generate the activity patterns for breathing and contribute to various sensory responses including changes in O2 and CO2. These complex sensorimotor tasks depend on the dynamic interplay between numerous cellular building blocks that consist of voltage-, calcium-, and ATP-dependent ionic conductances, various ionotropic and metabotropic synaptic mechanisms, as well as neuromodulators acting on G-protein coupled receptors and second messenger systems. As described in this review, the sensorimotor responses of the respiratory network emerge through the state-dependent integration of all these building blocks. There is no known respiratory function that involves only a small number of intrinsic, synaptic, or modulatory properties. Because of the complex integration of numerous intrinsic, synaptic, and modulatory mechanisms, the respiratory network is capable of continuously adapting to changes in the external and internal environment, which makes breathing one of the most integrated behaviors. Not surprisingly, inspiration is critical not only in the control of ventilation, but also in the context of “inspiring behaviors” such as arousal of the mind and even creativity. Far-reaching implications apply also to the underlying network mechanisms, as lessons learned from the respiratory network apply to network functions in general. PMID:23720262

  4. Bacterial production of short-chain organic acids and trehalose from levulinic acid: a potential cellulose-derived building block as a feedstock for microbial production.

    PubMed

    Habe, Hiroshi; Sato, Shun; Morita, Tomotake; Fukuoka, Tokuma; Kirimura, Kohtaro; Kitamoto, Dai

    2015-02-01

    Levulinic acid (LA) is a platform chemical derived from cellulosic biomass, and the expansion of LA utilization as a feedstock is important for production of a wide variety of chemicals. To investigate the potential of LA as a substrate for microbial conversion to chemicals, we isolated and identified LA-utilizing bacteria. Among the six isolated strains, Pseudomonas sp. LA18T and Rhodococcus hoagie LA6W degraded up to 70 g/L LA in a high-cell-density system. The maximal accumulation of acetic acid by strain LA18T and propionic acid by strain LA6W was 13.6 g/L and 9.1 g/L, respectively, after a 4-day incubation. Another isolate, Burkholderia stabilis LA20W, produced trehalose extracellularly in the presence of 40 g/L LA to approximately 2 g/L. These abilities to produce useful compounds supported the potential of microbial LA conversion for future development and cellulosic biomass utilization.

  5. Determining Possible Building Blocks of the Earth

    NASA Technical Reports Server (NTRS)

    Burbine, T. H.; O'Brien, K. M.

    2003-01-01

    Introduction: One of the fundamental questions concerning the formation of the Earth is what is it made out of. The Earth appears to have condensed out of material from the solar nebula. We sample this "primitive" material in the form of chondritic meteorites. One of the most important constraints on possible building blocks for the Earth is the Earth#s oxygen iso-topic composition. Rocks from the Earth and Moon plot along a line (the terrestrial fractionation line) in diagrams of delta(sup 17)O (% relative to Standard Mean Ocean Water or SMOW) versus delta(sup 18)O (% relative to SMOW). Chondritic meteorites fall above and below this line. Distances from this line are given as Delta(sup 17)O (%) (= delta(sup 17)O - 0.52 x delta(sup 18)O).

  6. Alkoxyallenes as building blocks for organic synthesis.

    PubMed

    Zimmer, Reinhold; Reissig, Hans-Ulrich

    2014-05-07

    Alkoxyallenes are unusually versatile C3 building blocks in organic synthesis. Hence this tutorial review summarizes the most important transformations, including subsequent reactions and their applications in the synthesis of relevant compounds, e.g. natural products. The reactivity patterns involved and the synthons derived from alkoxyallenes are presented. Often alkoxyallenes can serve as substitutes of acrolein or acrolein acetals, utilisation of which has already led to interesting products. Most important is the use of lithiated alkoxyallenes which smoothly react with a variety of electrophiles and lead to products with unique substitution patterns. The heterocycles or carbocycles formed are intermediates for the stereoselective synthesis of natural products or for the preparation of other structurally relevant compounds. The different synthons being put into practice by the use of lithiated alkoxyallenes in these variations will be discussed.

  7. HUBBLE AND KECK DISCOVER GALAXY BUILDING BLOCK

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This NASA Hubble Space Telescope image shows a very small, faint galaxy 'building block' newly discovered by a unique collaboration between ground- and space-based telescopes. Hubble and the 10-meter Keck Telescopes in Hawaii joined forces, using a galaxy cluster which acts as gravitational lens to detect what scientists believe is one of the smallest very distant objects ever found. The galaxy cluster Abell 2218 was used by a team of European and American astronomers led by Richard Ellis (Caltech) in their systematic search for intrinsically faint distant star-forming systems. Without help from Abell 2218's exceptional magnifying power to make objects appear about 30 times brighter, the galaxy building block would have been undetectable. In the image to the right, the object is seen distorted into two nearly identical, very red 'images' by the gravitational lens. The image pair represents the magnified result of a single background object gravitationally lensed by Abell 2218 and viewed at a distance of 13.4 billion light-years. The intriguing object contains only one million stars, far fewer than a mature galaxy, and scientists believe it is very young. Such young star-forming systems of low mass at early cosmic times are likely to be the objects from which present-day galaxies have formed. In the image to the left, the full overview of the galaxy cluster Abell 2218 is seen. This image was taken by Hubble in 1999 at the completion of Hubble Servicing Mission 3A. Credit: NASA, ESA, Richard Ellis (Caltech) and Jean-Paul Kneib (Observatoire Midi-Pyrenees, France) Acknowledgment: NASA, A. Fruchter and the ERO Team (STScI and ST-ECF)

  8. Chiral Perylene Diimides: Building Blocks for Ionic Self‐Assembly

    PubMed Central

    Echue, Geraldine; Lloyd‐Jones, Guy C.

    2015-01-01

    Abstract A chiral perylene diimide building block has been prepared based on an amine derivative of the amino acid l‐phenylalanine. Detailed studies were carried out into the self‐assembly behaviour of the material in solution and the solid state using UV/Vis, circular dichroism (CD) and fluorescence spectroscopy. For the charged building block BTPPP, the molecular chirality of the side chains is translated into the chiral supramolecular structure in the form of right‐handed helical aggregates in aqueous solution. Temperature‐dependent UV/Vis studies of BTPPP in aqueous solution showed that the self‐assembly behaviour of this dye can be well described by an isodesmic model in which aggregation occurs to generate short stacks in a reversible manner. Wide‐angle X‐ray diffraction studies (WXRD) revealed that this material self‐organises into aggregates with π–π stacking distances typical for π‐conjugated materials. TEM investigations revealed the formation of self‐assembled structures of low order and with no expression of chirality evident. Differential scanning calorimetry (DSC) and polarised optical microscopy (POM) were used to investigate the mesophase properties. Optical textures representative of columnar liquid–crystalline phases were observed for solvent‐annealed samples of BTPPP. The high solubility, tunable self‐assembly and chiral ordering of these materials demonstrate their potential as new molecular building blocks for use in the construction of chiro‐optical structures and devices. PMID:25689392

  9. Galactic Building Blocks Seen Swarming Around Andromeda

    NASA Astrophysics Data System (ADS)

    2004-02-01

    Green Bank, WV - A team of astronomers using the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) has made the first conclusive detection of what appear to be the leftover building blocks of galaxy formation -- neutral hydrogen clouds -- swarming around the Andromeda Galaxy, the nearest large spiral galaxy to the Milky Way. This discovery may help scientists understand the structure and evolution of the Milky Way and all spiral galaxies. It also may help explain why certain young stars in mature galaxies are surprisingly bereft of the heavy elements that their contemporaries contain. Andromeda Galaxy This image depicts several long-sought galactic "building blocks" in orbit of the Andromeda Galaxy (M31). The newfound hydrogen clouds are depicted in a shade of orange (GBT), while gas that comprises the massive hydrogen disk of Andromeda is shown at high-resolution in blue (Westerbork Sythesis Radio Telescope). CREDIT: NRAO/AUI/NSF, WSRT (Click on Image for Larger Version) "Giant galaxies, like Andromeda and our own Milky Way, are thought to form through repeated mergers with smaller galaxies and through the accretion of vast numbers of even lower mass 'clouds' -- dark objects that lack stars and even are too small to call galaxies," said David A. Thilker of the Johns Hopkins University in Baltimore, Maryland. "Theoretical studies predict that this process of galactic growth continues today, but astronomers have been unable to detect the expected low mass 'building blocks' falling into nearby galaxies, until now." Thilker's research is published in the Astrophysical Journal Letters. Other contributors include: Robert Braun of the Netherlands Foundation for Research in Astronomy; Rene A.M. Walterbos of New Mexico State University; Edvige Corbelli of the Osservatorio Astrofisico di Arcetri in Italy; Felix J. Lockman and Ronald Maddalena of the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia; and Edward Murphy of the

  10. The use of explicit building blocks in evolutionary computation

    NASA Astrophysics Data System (ADS)

    Sangkavichitr, Chalermsub; Chongstitvatana, Prabhas

    2016-02-01

    This paper proposes a new algorithm to identify and compose building blocks. Building blocks are interpreted as common subsequences between good individuals. The proposed algorithm can extract building blocks from a population explicitly. Explicit building blocks are identified from shared alleles among multiple chromosomes. These building blocks are stored in an archive. They are recombined to generate offspring. The additively decomposable problems and hierarchical decomposable problems are used to validate the algorithm. The results are compared with the Bayesian optimisation algorithm, the hierarchical Bayesian optimisation algorithm, and the chi-square matrix. This proposed algorithm is simple, effective, and fast. The experimental results confirm that building block identification is an important process that guides the recombination procedure to improve the solutions. In addition, the method efficiently solves hard problems.

  11. Quaterpyrroles as building blocks for the synthesis of expanded porphyrins.

    PubMed

    Anguera, Gonzalo; Kauffmann, Brice; Borrell, José I; Borrós, Salvador; Sánchez-García, David

    2015-05-01

    A new family of quaterpyrroles and their application as building blocks for the synthesis of macrocycles is reported. The preparation of these quaterpyrroles consisted of two synthetic steps: bromination of 2,2'-bipyrroles bearing two electron-withdrawing groups followed by Suzuki coupling with 1-(tert-butoxycarbonyl)pyrrole-2-boronic acid. The resulting quaterpyrroles have been used to prepare an octaphyrin and a substituted cyclo[8]pyrrole. Additionally, the synthesis of a new macrocycle containing the quaterpyrrole and 2,5-di(1H-pyrrol-2-yl)thiophene moieties is presented.

  12. Building Blocks for Sustainable Communities: Assistance from Grantees

    EPA Pesticide Factsheets

    EPA awarded Building Blocks for Sustainable Communities grants to four nonprofit organizations with extensive expertise in community sustainability. These organizations deliver technical assistance to communities.

  13. A Difluorobenzoxadiazole Building Block for Efficient Polymer Solar Cells.

    PubMed

    Zhao, Jingbo; Li, Yunke; Hunt, Adrian; Zhang, Jianquan; Yao, Huatong; Li, Zhengke; Zhang, Jie; Huang, Fei; Ade, Harald; Yan, He

    2016-03-02

    A difluorobenzoxadiazole building block is synthesized and utilized to construct a conjugated polymer leading to high-performance thick-film polymer solar cells with a V(OC) of 0.88 V and a power conversion efficiency of 9.4%. This new building block can be used in many possible polymer structures for various organic electro-nic applications.

  14. Trihaloethenes as versatile building blocks for organic synthesis.

    PubMed

    Grossmann, Adriana S; Magauer, Thomas

    2016-06-15

    This review highlights the chemistry of trihaloethene building blocks with a special focus on commercially available 1,1,2-trichloroethene. The topics surveyed herein include the use of trihaloethenes as C2-building blocks for transition metal-catalyzed coupling reactions, addition, elimination and cycloaddition reactions as well as natural product syntheses.

  15. Building Blocks: Enmeshing Technology and Creativity with Artistic Pedagogical Technologies

    ERIC Educational Resources Information Center

    Janzen, Katherine J.; Perry, Beth; Edwards, Margaret

    2017-01-01

    Using the analogy of children's building blocks, the reader is guided through the results of a research study that explored the use of three Artistic Pedagogical Technologies (APTs). "Building blocks" was the major theme that emerged from the data. Sub-themes included developing community, enhancing creativity, and risk taking. The…

  16. Countering Depression with the Five Building Blocks of Resilience.

    ERIC Educational Resources Information Center

    Grotberg, Edith H.

    1999-01-01

    Provides strategies for reducing the risk of youth retreating into depression when faced with adversities in life, by helping them develop the building blocks of resilience (trust, autonomy, initiative, industry, identity). Reports that these building blocks have proven effective in fostering and strengthening resilience. (Author/JDM)

  17. Data Policy Construction Set - Building Blocks from Childhood Constructions

    NASA Astrophysics Data System (ADS)

    Fleischer, Dirk; Paul-Stueve, Thilo; Jobmann, Alexandra; Farrenkopf, Stefan

    2016-04-01

    A complete construction set of building blocks usually comes with instructions and these instruction include building stages. The products of these building stages usually build from very general parts become highly specialized building parts for very unique features of the whole construction model. This sounds very much like the construction or organization of an interdisciplinary research project, institution or association, doesn't it! The creation process of an overarching data policy for a project group or institution is exactly the combination of individual interests with the common goal of a collaborative data policy and can be compared with the building stages of a construction set of building blocks and the building instructions. Keeping this in mind we created the data policy construction set of textual building blocks. This construction set is subdivided into several building stages or parts each containing multiple building blocks as text blocks. By combining building blocks of all subdivisions it is supposed to create a cascading data policy document. Cascading from the top level as a construction set provider for all further down existing levels such as project, themes, work packages or Universities, faculties, institutes down to the working level of working groups. The working groups are picking from the remaining building blocks in the provided construction set the suitable blocks for its working procedures to create a very specific policy from the available construction set provided by the top level community. Nevertheless, if a working group realized that there are missing building blocks or worse that there are missing building parts, then they have the chance to add the missing pieces to the construction set of direct an future use. This cascading approach enables project or institution wide application of the encoded rules from the textual level on access to data storage infrastructure. This structured approach is flexible enough to allow for

  18. Microporous solids designed from molecular building blocks

    NASA Astrophysics Data System (ADS)

    Davis, Charles Earnest

    The synthesis, characterization, and application of porous materials has experienced explosive growth in the last fifty years. An increased number of technologies are based on the unique properties of rigid, open framework solids in areas such as molecular and ionic separations, sensors, and catalysts. However, until recently, the only well characterized solids that have seen extensive application were metal oxide frameworks such as the aluminosilicate zeolites and aluminophosphates. The syntheses of these materials have lacked the ability to design and control the properties of the solid. Therefore, this work has focused on the concept of directed synthesis employing molecular building blocks in an attempt to tailor open framework systems based on simple chemical functionality. Towards this goal, highly symmetric molecular species with well defined reactive sites have been polymerized through metal centers in the presence of templating agents and potential guests. Highly crystalline solids were obtained using a variety of techniques including vapor and gel diffusion, recrystallization, and hydrothermal synthesis. Complete characterization of the structure and properties has been achieved using elemental microanalysis, infrared spectroscopy, powder and single crystal x-ray analysis, nuclear magnetic resonance spectroscopy, thermogravimetry, and gas chromatography. These new materials are based on the linking of germanium sulfide cages and polycarboxylic aromatic rings with transition metal ions. The fundamental problems of interpenetrating networks, poor structural rigidity in the absence of guests, and low crystallinity have been overcome to produce highly selective, stable frameworks capable of ion exchange, molecular selectivity, and potentially catalysis. Furthermore, the concept of selectivity based on electronic character and functionality has been introduced and demonstrated. This unique property is believed to be the result of metal center accessibility in

  19. NANOSTRUCTURED METAL OXIDE CATALYSTS VIA BUILDING BLOCK SYNTHESES

    SciTech Connect

    Craig E. Barnes

    2013-03-05

    A broadly applicable methodology has been developed to prepare new single site catalysts on silica supports. This methodology requires of three critical components: a rigid building block that will be the main structural and compositional component of the support matrix; a family of linking reagents that will be used to insert active metals into the matrix as well as cross link building blocks into a three dimensional matrix; and a clean coupling reaction that will connect building blocks and linking agents together in a controlled fashion. The final piece of conceptual strategy at the center of this methodology involves dosing the building block with known amounts of linking agents so that the targeted connectivity of a linking center to surrounding building blocks is obtained. Achieving targeted connectivities around catalytically active metals in these building block matrices is a critical element of the strategy by which single site catalysts are obtained. This methodology has been demonstrated with a model system involving only silicon and then with two metal-containing systems (titanium and vanadium). The effect that connectivity has on the reactivity of atomically dispersed titanium sites in silica building block matrices has been investigated in the selective oxidation of phenols to benezoquinones. 2-connected titanium sites are found to be five times as active (i.e. initial turnover frequencies) than 4-connected titanium sites (i.e. framework titanium sites).

  20. Ionization of amphiphilic acidic block copolymers.

    PubMed

    Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco

    2012-06-28

    The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.

  1. New 1:1 and 2:1 salts in the `DL-norvaline-maleic acid' system as an example of assembling various crystal structures from similar supramolecular building blocks.

    PubMed

    Arkhipov, Sergey G; Losev, Evgeniy A; Boldyreva, Elena V

    2017-01-01

    Molecular salts and cocrystals of amino acids have potential applications as molecular materials with nonlinear optical, ferroelectric, piezoelectric, and other various target physical properties. The wide choice of amino acids and coformers makes it possible to design various crystal structures. The amino acid-maleic acid system provides a perfect example of a rich variety of crystal structures with different stoichiometries, symmetries and packing motifs built from the molecular building blocks, which are either exactly the same, or differ merely by protonation or as optical isomers. The present paper reports the crystal structures of two new salts of the DL-norvaline-maleic acid system with 1:1 and 2:1 stoichiometries, namely DL-norvalinium hydrogen maleate, C5H12NO2(+)·C4H3O4(-), (I), and DL-norvalinium hydrogen maleate-DL-norvaline, C5H12NO2(+)·C4H3O4(-)·C5H11NO2, (II). These are the first examples of molecular salts of DL-norvaline with an organic anion. The crystal structure of (I) has the same C2(2)(12) structure-forming motif which is common for hydrogen maleates of amino acids. The structure of (II) has dimeric cations. Of special interest is that the single crystals of (I) which are originally formed on crystallization from aqueous solution transform into single crystals of (II) if stored in the mother liquor for several hours.

  2. DNA Building Blocks Can Be Made in Space

    NASA Video Gallery

    NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research g...

  3. Big Questions: The Ultimate Building Blocks of Matter

    ScienceCinema

    Lincoln, Don

    2016-07-12

    The Standard Model of particle physics treats quarks and leptons as having no size at all. Quarks are found inside protons and neutrons and the most familiar lepton is the electron. While the best measurements to date support that idea, there is circumstantial evidence that suggests that perhaps the these tiny particles might be composed of even smaller building blocks. This video explains this circumstantial evidence and introduces some very basic ideas of what those building blocks might be.

  4. Big Questions: The Ultimate Building Blocks of Matter

    SciTech Connect

    Lincoln, Don

    2013-11-06

    The Standard Model of particle physics treats quarks and leptons as having no size at all. Quarks are found inside protons and neutrons and the most familiar lepton is the electron. While the best measurements to date support that idea, there is circumstantial evidence that suggests that perhaps the these tiny particles might be composed of even smaller building blocks. This video explains this circumstantial evidence and introduces some very basic ideas of what those building blocks might be.

  5. Building Trades. Block III. Floor Framing.

    ERIC Educational Resources Information Center

    Texas A and M Univ., College Station. Vocational Instructional Services.

    This document contains three units of a course on floor framing to be used as part of a building trades program. Each unit consists, first, of an informational lesson, with complete lesson plan for the teacher's use. Included in each lesson plan are the lesson aim; lists of teaching aids, materials, references, and prerequisites for students;…

  6. Intercultural Communication Activities in the Classroom: Turning Stumbling Blocks into Building Blocks.

    ERIC Educational Resources Information Center

    Dillon, Randy K.

    This paper explores behavior patterns that inhibit effective communication in everyday, educational, and business cross-cultural settings. Opportunities to change these inhibiting patterns, metaphorically referred to as "stumbling blocks," into building blocks or tools for successful intercultural understandings are discussed in the…

  7. MECs: "Building Blocks" for Creating Biological and Chemical Instruments.

    PubMed

    Hill, Douglas A; Anderson, Lindsey E; Hill, Casey J; Mostaghim, Afshin; Rodgers, Victor G J; Grover, William H

    2016-01-01

    The development of new biological and chemical instruments for research and diagnostic applications is often slowed by the cost, specialization, and custom nature of these instruments. New instruments are built from components that are drawn from a host of different disciplines and not designed to integrate together, and once built, an instrument typically performs a limited number of tasks and cannot be easily adapted for new applications. Consequently, the process of inventing new instruments is very inefficient, especially for researchers or clinicians in resource-limited settings. To improve this situation, we propose that a family of standardized multidisciplinary components is needed, a set of "building blocks" that perform a wide array of different tasks and are designed to integrate together. Using these components, scientists, engineers, and clinicians would be able to build custom instruments for their own unique needs quickly and easily. In this work we present the foundation of this set of components, a system we call Multifluidic Evolutionary Components (MECs). "Multifluidic" conveys the wide range of fluid volumes MECs operate upon (from nanoliters to milliliters and beyond); "multi" also reflects the multiple disciplines supported by the system (not only fluidics but also electronics, optics, and mechanics). "Evolutionary" refers to the design principles that enable the library of MEC parts to easily grow and adapt to new applications. Each MEC "building block" performs a fundamental function that is commonly found in biological or chemical instruments, functions like valving, pumping, mixing, controlling, and sensing. Each MEC also has a unique symbol linked to a physical definition, which enables instruments to be designed rapidly and efficiently using schematics. As a proof-of-concept, we use MECs to build a variety of instruments, including a fluidic routing and mixing system capable of manipulating fluid volumes over five orders of magnitude, an

  8. Building blocks of the Milky Way's accreted spheroid

    NASA Astrophysics Data System (ADS)

    van Oirschot, Pim; Starkenburg, Else; Helmi, Amina; Nelemans, Gijs

    2017-01-01

    In the Λcold dark matter model of structure formation, a stellar spheroid grows by the assembly of smaller galaxies, the so-called building blocks. Combining the Munich-Groningen semi-analytical model of galaxy formation with the high-resolution Aquarius simulations of dark matter haloes, we study the assembly history of the stellar spheroids of six Milky Way-mass galaxies, focusing on building block properties such as mass, age and metallicity. These properties are compared to those of the surviving satellites in the same models. We find that the building blocks have higher star formation rates on average, and this is especially the case for the more massive objects. At high redshift, these dominate in star formation over the satellites, whose star formation time-scales are longer on average. These differences ought to result in a larger α-element enhancement from Type II supernovae in the building blocks (compared to the satellites) by the time Type Ia supernovae would start to enrich them in iron, explaining the observational trends. Interestingly, there are some variations in the star formation time-scales of the building blocks amongst the simulated haloes, indicating that [α/Fe] abundances in spheroids of other galaxies might differ from those in our own Milky Way.

  9. Synthesis and alkylation of aza-glycinyl dipeptide building blocks.

    PubMed

    Garcia-Ramos, Yesica; Lubell, William D

    2013-12-01

    Aza-glycinyl dipeptides are useful building blocks for the synthesis of a diverse array of azapeptides. The construction of the aza-glycine residue is however challenging, because of the potential for side reactions, such as those leading to formation of oxadiazalone, hydantoin and symmetric urea by-products. Employing N,N'-disuccinimidyl carbonate to activate benzophenone hydrazone, we have developed a more efficient approach for the synthesis of aza-glycinyl dipeptides. Alkylation of the semicarbazone of the resulting protected aza-glycinyl dipeptides using tetraethylammonium hydroxide and propargyl bromide provided an efficient entry into the aza-propargylglycinyl peptide building blocks, which have served previously in various reactions including Sonogashira cross-couplings, dipolar cycloadditions and intramolecular exo-dig cycloadditions to furnish a variety of azapeptide building blocks.

  10. Principles of nanostructure design with protein building blocks.

    PubMed

    Tsai, Chung-Jung; Zheng, Jie; Zanuy, David; Haspel, Nurit; Wolfson, Haim; Alemán, Carlos; Nussinov, Ruth

    2007-07-01

    Currently there is increasing interest in nanostructures and their design. Nanostructure design involves the ability to predictably manipulate the properties of the self-assembly of autonomous units. Autonomous units have preferred conformational states. The units can be synthetic material science-based or derived from functional biological macromolecules. Autonomous biological building blocks with available structures provide an extremely rich and useful resource for design. For proteins, the structural databases contain large libraries of protein molecules and their building blocks with a range of shapes, surfaces, and chemical properties. The introduction of engineered synthetic residues or short peptides into these can expand the available chemical space and enhance the desired properties. Here we focus on the principles of nanostructure design with protein building blocks.

  11. Sodium phosphaethynolate as a building block for heterocycles.

    PubMed

    Chen, Xiaodan; Alidori, Simone; Puschmann, Florian Frank; Santiso-Quinones, Gustavo; Benkő, Zoltán; Li, Zhongshu; Becker, Gerd; Grützmacher, Hans-Friedrich; Grützmacher, Hansjörg

    2014-02-03

    Phosphorus-containing heterocycles have evolved from laboratory curiosities to functional components, such as ligands in catalytically active metal complexes or molecular constituents in electronic devices. The straightforward synthesis of functionalized heterocycles on a larger scale remains a challenge. Herein, we report the use of the phosphaethynolate (OCP)(-) anion as a building block for various sterically unprotected and functionalized hydroxy substituted phosphorus heterocycles. Because the resulting heterocycles are themselves anions, they are building blocks in their own right and allow further facile functionalization. This property may be of interest in coordination chemistry and material science.

  12. Large space erectable structures - building block structures study

    NASA Technical Reports Server (NTRS)

    Armstrong, W. H.; Skoumal, D. E.; Straayer, J. W.

    1977-01-01

    A modular planar truss structure and a long slender boom concept identified as building block approaches to construction of large spacecraft configurations are described. The concepts are compatible in weight and volume goals with the Space Transportation System, use standard structural units, and represent high on-orbit productivity in terms of structural area or beam length. Results of structural trade studies involving static and dynamic analyses of a single module and rigid body deployment analyses to assess kinetics and kinematics of automatic deployment of the building block modules are presented.

  13. Determining Possible Building Blocks of the Earth and Mars

    NASA Technical Reports Server (NTRS)

    Burbine, T. H.; OBrien, K. M.

    2004-01-01

    One of the fundamental questions concerning planetary formation is exactly what material did the planets form from? All the planets in our solar system are believed to have formed out of material from the solar nebula. Chondritic meteorites appear to sample this primitive material. Chondritic meteorites are generally classified into 13 major groups, which have a variety of compositions. Detailed studies of possible building blocks of the terrestrial planets require samples that can be used to estimate the bulk chemistry of these bodies. This study will focus on trying to determine possible building blocks of Earth and Mars since samples of these two planets can be studied in detail in the laboratory.

  14. Isolated galaxies: residual of primordial building blocks?

    NASA Astrophysics Data System (ADS)

    Galletta, G.; Rodighiero, G.; Bettoni, D.; Moles, M.; Varela, J.

    2006-09-01

    Context: .The mass assembly is believed to be the dominant process of early galaxy formation. This mechanism of galaxy building can proceed either by repeated major mergers with other systems, or by means of accretion of matter from the surrounding regions. Aims: .In this paper we compare the properties of local disk galaxies that appear isolated, i.e., not tidally affected by other galaxies during the last few Gyr within the volume given by cz≤ 5000 km s-1, with those galaxies at z values from 0.25 to 5. Methods: .Effective radii for 203 isolated galaxies and 1645 galaxies from the RC3 have been collected and the two samples have been analyzed statistically. A similar comparison has been made with half light radii studied at high z from the literature. Results: .We found that isolated galaxies are, in general, smaller than other present epoch galaxies from the RC3. We notice the lack of systems larger than 7 kpc among them. Their size distribution appears to be similar to that of galaxies at 1.4 ≤ z ≤ 2. The models of the merging history also indicate that the isolated galaxies did stop their merging process at about that redshift, evolving passively since then. The galaxy density seems to have remained unchanged since that epoch Conclusions: .Isolated galaxies appear to be the end products of the merging process, as proposed by the hierarchical accretion scenario at around z=1.4. For this class of galaxies, this was the last significant merging event in their lives, and they have evolved passively since then. This is confirmed by the analytical estimate of the merging fraction with z and by the comparison with sizes of distant galaxies.

  15. Charge-tunable indium-organic frameworks built from cationic, anionic, and neutral building blocks.

    PubMed

    Bu, Fei; Lin, Qipu; Zhai, Quan-Guo; Bu, Xianhui; Feng, Pingyun

    2015-10-14

    By using the same ligand, 2,5-furandicarboxylic acid (FDA), and varying synthetic conditions (especially the In(3+)/FDA ratio), it is possible to access three unique building blocks of indium, demonstrating charge-switching from a positive trimer to a negative monomer and leading to the synthesis of In-MOFs with tunable framework charge.

  16. QM Computations on Complete Nucleic Acids Building Blocks: Analysis of the Sarcin-Ricin RNA Motif Using DFT-D3, HF-3c, PM6-D3H, and MM Approaches.

    PubMed

    Kruse, Holger; Havrila, Marek; Šponer, Jiřı

    2014-06-10

    A set of conformations obtained from explicit solvent molecular dynamics (MD) simulations of the Sarcin-Ricin internal loop (SRL) RNA motif is investigated using quantum mechanical (QM, TPSS-D3/def2-TZVP DFT-D3) and molecular mechanics (MM, AMBER parm99bsc0+χol3 force field) methods. Solvent effects are approximated using implicit solvent methods (COSMO for DFT-D3; GB and PB for MM). Large-scale DFT-D3 optimizations of the full 11-nucleotide motif are compared to MM results and reveal a higher flexibility of DFT-D3 over the MM in the optimization procedure. Conformational energies of the SRL motif expose significant differences in the DFT-D3 and MM energy descriptions that explain difficulties in MD simulations of the SRL motif. The TPSS-D3 data are in excellent agreement with results obtained by the hybrid functionals PW6B95-D3 and M06-2X. Computationally more efficient methods such as PM6-D3H and HF-3c show promising but partly inconsistent results. It is demonstrated that large-scale DFT-D3 computations on complete nucleic acids building blocks are a viable tool to complement the picture obtained from MD simulations and can be used as benchmarks for faster computational methods. Methodological challenges of large-scale QM computations on nucleic acids such as missing solvent-solute interactions and the truncation of the studied systems are discussed.

  17. Origami-inspired building block and parametric design for mechanical metamaterials

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; Ma, Hua; Feng, Mingde; Yan, Leilei; Wang, Jiafu; Wang, Jun; Qu, Shaobo

    2016-08-01

    An origami-based building block of mechanical metamaterials is proposed and explained by introducing a mechanism model based on its geometry. According to our model, this origami mechanism supports response to uniaxial tension that depends on structure parameters. Hence, its mechanical properties can be tunable by adjusting the structure parameters. Experiments for poly lactic acid (PLA) samples were carried out, and the results are in good agreement with those of finite element analysis (FEA). This work may be useful for designing building blocks of mechanical metamaterials or other complex mechanical structures.

  18. Statistical analysis of atmospheric turbulence about a simulated block building

    NASA Technical Reports Server (NTRS)

    Steely, S. L., Jr.

    1981-01-01

    An array of towers instrumented to measure the three components of wind speed was used to study atmospheric flow about a simulated block building. Two-point spacetime correlations of the longitudinal velocity component were computed along with two-point spatial correlations. These correlations are in good agreement with fundamental concepts of fluid mechanics. The two-point spatial correlations computed directly were compared with correlations predicted by Taylor's hypothesis and excellent agreement was obtained at the higher levels which were out of the building influence. The correlations fall off significantly in the building wake but recover beyond the wake to essentially the same values in the undisturbed, higher regions.

  19. Using Building-Block Puzzles to Practice Drawing Organic Mechanisms

    ERIC Educational Resources Information Center

    Erdik, Ender

    2005-01-01

    A study uses a thought-provoking, pencil-and-paper activity to aid students in writing organic reaction mechanisms. Organic and functional groups that constitute the formulas of organic and inorganic reactants, ionic intermediates, and products are presented as building blocks, which must be placed correctly in a given puzzle so that they bind…

  20. Synthesis and Minisci Reactions of Organotrifluoroborato Building Blocks

    PubMed Central

    Presset, Marc; Fleury-Brégeot, Nicolas; Oehlrich, Daniel

    2013-01-01

    Copper-catalyzed borylation of a variety of organic halides with bis(pinacolato)diboron allows the preparation of diverse potassium organotrifluoroborates. The reactions are mild and general, providing access to a variety of interesting, boron-containing building blocks, including those containing piperidine, pyrrole, azetidine, tetrahydropyran and oxetane substructures. Representative Minisci reactions are reported for select examples. PMID:23594305

  1. Phytoproteins in green leaves as building blocks for photosynthesis of gold nanoparticles: An efficient electrocatalyst towards the oxidation of ascorbic acid and the reduction of hydrogen peroxide.

    PubMed

    Megarajan, Sengan; Ayaz Ahmed, Khan Behlol; Rajendra Kumar Reddy, G; Suresh Kumar, P; Anbazhagan, Veerappan

    2016-02-01

    Herein, we present a simple and green method for the synthesis of gold nanoparticles (AuNPs) using the phytoproteins of spinach leaves. Under ambient sunlight irradiation, the isolated phytoprotein complex from spinach leaves reduces the gold chloride aqueous solution and stabilizes the formed AuNPs. As prepared nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, zeta potential, transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDS). The surface plasmon resonance (SPR) maximum for AuNPs was observed at 520 nm. The zeta potential value estimated for the AuNPs is -27.0 mV, indicating that the NPs are well separated. Transmission electron micrographs revealed that the particles are spherical in nature with the size range from 10 to 15 nm. AuNPs act as a catalyst in the degradation of an azo dye, methyl orange in an aqueous environment. The reduction rate was determined to be pseudo-first order. Electrocatalytic efficiency of the synthesized AuNPs via this green approach was studied by chronoamperometry using ascorbic acid and hydrogen peroxide as a model compound for oxidation and reduction, respectively. Electrocatalytic studies indicate that the gold nanoparticles can be used to detect ascorbic acid and hydrogen peroxide in micromolar concentrations with response time less than 3s.

  2. A building block approach towards novel nonlinear optical materials

    NASA Astrophysics Data System (ADS)

    Bhaskar, Ajit

    The purpose of the present research is to develop and apply a building block approach towards the design of novel nonlinear optical (NLO) materials, capable of exhibiting enhanced Two-Photon Absorption (TPA) behavior. These materials have potential applications in biological imaging, microfabrication, sensing, photodynamic cancer therapy, optical limiting and ultrafast switching. Electronic structure, symmetry and intermolecular forces are vital for designing the right building block. The next step is to connect them to form macromolecules. However, besides covalent bonding, aggregation and self assembly of building blocks can also be utilized, which renders the strategies for materials design less reliant on chemical synthesis. The application of building block approach was illustrated using several examples, including rigid, two-dimensional architectures. These enabled the investigation of macrostructures that were synthetically inaccessible as well as demonstrated the influence of symmetry on TPA behavior. Electronic coupling between building blocks and excited state dynamics were the observed reasons for enhanced TPA. In an attempt to investigate strong coupling that would extend over the entire chromophore, novel "endless" nano-cavities were examined for their TPA behavior. Using the tools of ultrafast spectroscopy, complete delocalization was proved in these materials. Similar enhancement in giant porphyrin macrocycles, which mimic natural light harvesting systems, was observed. Another approach to harness the coupling between small building blocks in a synergistic fashion is to arrange them into branched architectures. The influence of pi-character of branching units on the charge transfer character, which in turn influences the TPA behavior, was examined. Using excited state studies, not only was it observed that alkene pi-bridging resulted in enhancement of TPA behavior over alkyne pi-bridging, but also the mechanism for cooperative enhancement upon

  3. Synthesis of novel enantiopure fluorinated building blocks from acyclic chiral allylsilanes.

    PubMed

    Tredwell, Matthew; Tenza, Kenny; Pacheco, Ma Carmen; Gouverneur, Véronique

    2005-09-29

    [reaction: see text] Homochiral beta-fluorinated gamma,delta-unsaturated carboxylic acids with an allylic fluorinated stereogenic center are available from the corresponding enantiopure allylsilanes. The key step for introduction of the fluorine substituent is an electrophilic fluorodesilylation reaction carried out in the presence of Selectfluor. Reduction of the resulting beta-fluorinated pentenoic acid into the corresponding fluorinated alcohol was also performed leading to the formation of an enantiopure second-generation fluorinated building block.

  4. COMPRESSOR BUILDING, TRA626. ELEVATIONS. WINDOWS. WALL SECTIONS. PUMICE BLOCK BUILDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    COMPRESSOR BUILDING, TRA-626. ELEVATIONS. WINDOWS. WALL SECTIONS. PUMICE BLOCK BUILDING HOUSED COMPRESSORS FOR AIRCRAFT NUCLEAR PROPULSION EXPERIMENTS. MTR-626-IDO-2S, 3/1952. INL INDEX NO. 531-0626-00-396-110535, REV. 2. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  5. Adolescent Boys' and Girls' Block Constructions Differ in Structural Balance: A Block-Building Characteristic Related to Math Achievement

    ERIC Educational Resources Information Center

    Casey, Beth M.; Pezaris, Elizabeth E.; Bassi, Julie

    2012-01-01

    Two studies were conducted on block building in adolescents, assessing middle school (Study 1) and high school students (Study 2). Students were asked to build something interesting with blocks. In both samples, the same pattern of gender differences were found; boys built taller structures than girls, and balanced a larger number of blocks on a…

  6. Development of potential manufacturing routes for substituted thiophenes – Preparation of halogenated 2-thiophenecarboxylic acid derivatives as building blocks for a new family of 2,6-dihaloaryl 1,2,4-triazole insecticides

    PubMed Central

    Hull, John W; Romer, Duane R; Podhorez, David E; Ash, Mezzie L; Brady, Christine H

    2007-01-01

    , which was readily converted to the acid chloride 2 with SOCl2. Conclusion The successful development of efficient synthetic routes to the halogenated thiophene building blocks 4-bromo-3-methyl-2-thiophenecarbonyl chloride 1, 3,4,5-trichloro-2-thiophenecarbonyl chloride 2, and 3,4,5-trichloro-2-thiophenecarbonitrile 3 paved the way for the development of viable commercial processes for XR-693 and XR-906, members of a new class of 2,6-dihaloaryl 1,2,4-triazole insecticides that exhibit selective activity against aphids, mites, and whiteflies coupled with low mammalian toxicity. The process development work for the experimental insecticide target molecules XR-693 and XR-906 will be the topic of a forthcoming paper. PMID:17784956

  7. Using carbon dioxide as a building block in organic synthesis.

    PubMed

    Liu, Qiang; Wu, Lipeng; Jackstell, Ralf; Beller, Matthias

    2015-01-20

    Carbon dioxide exits in the atmosphere and is produced by the combustion of fossil fuels, the fermentation of sugars and the respiration of all living organisms. An active goal in organic synthesis is to take this carbon--trapped in a waste product--and re-use it to build useful chemicals. Recent advances in organometallic chemistry and catalysis provide effective means for the chemical transformation of CO₂ and its incorporation into synthetic organic molecules under mild conditions. Such a use of carbon dioxide as a renewable one-carbon (C1) building block in organic synthesis could contribute to a more sustainable use of resources.

  8. Developing Building Blocks with Space Agencies: The Keys to Success

    NASA Astrophysics Data System (ADS)

    Poupat, Jean-Luc

    2014-08-01

    In their continuous efforts to offer building blocks for the European space industry, space agencies have supported the development of processing bricks dedicated to different applications such as platform computer or image compression.Since 25 years, Airbus Defence and Space (ex- Astrium) has developed more than 60 different ASICs components with their associated environment and has contributed to the achievements of some of these building blocks now available for the European space market and beyond.This paper proposes to come back on these developments that have led to products now operating in space in order to analyse the key elements behind their success. It will also demonstrate that the hardware components are nothing without a good ecosystem.

  9. Mission building blocks for outer solar system exploration.

    NASA Technical Reports Server (NTRS)

    Herman, D.; Tarver, P.; Moore, J.

    1973-01-01

    Description of the technological building blocks required for exploring the outer planets with maximum scientific yields under stringent resource constraints. Two generic spacecraft types are considered: the Mariner and the Pioneer. Following a discussion of the outer planet mission constraints, the evolutionary development of spacecraft, probes, and propulsion building blocks is presented. Then, program genealogies are shown for Pioneer and Mariner missions and advanced propulsion systems to illustrate the soundness of a program based on spacecraft modification rather than on the development of new spacecraft for each mission. It is argued that, for minimum costs, technological advancement should occur in an evolutionary manner from mission to mission. While this strategy is likely to result in compromises on specific missions, the realization of the overall objectives calls for an advance commitment to the entire mission series.

  10. Development of a prototype self-configuring building block

    NASA Astrophysics Data System (ADS)

    Lin, Hung-Yu; Tsui, Chi-Leung; Wu, Wen-Jong; Wang, Wei-Chih

    2011-04-01

    The paper presents the concept and construction of a prototype self-configuring building block for potential application in smart dynamic structure. The design contains several modular self-configuring blocks with integrated controllers, gear trains, extending arms and magnetic latches. The structure could be reconfigured via the connection and disconnection of magnetic latch between the modules. Through the coordination of the individual cubes themselves, the entire structure can reassemble via pushing and pulling the individual components into almost any desired shape. Information as to the current location or the next necessary movement could be passed from cube to cube by a physical connection between the cubes or remotely through broadcast signals. To provide the hardware strategy, we present the mechanical design of the self-configure modules and their latch mechanism of Halbach array. In the end, we will discuss our proposed application in dynamic building structure and storage management.

  11. 51. Owsley Block, 43 East Park, 1889. This building features ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. Owsley Block, 43 East Park, 1889. This building features projecting bay window units, and curved balconies on the upper two floors, and modernized storefronts at the ground level. It was built for William Owsley, who served a Mayor of Butte 1884-1885. It originally had two storefronts, with lodgings and meeting rooms for clubs above. - Butte Historic District, Bounded by Copper, Arizona, Mercury & Continental Streets, Butte, Silver Bow County, MT

  12. Building block for an orthonormal-lattice-filter adaptive network

    NASA Astrophysics Data System (ADS)

    Gabriel, W. F.

    1980-07-01

    The recent algorithm for a multistage multichannel orthonormal lattice filter proposed by M. Aftab Alam is a welcome addition to the library of adaptive-processing algorithms and provides a flexible alternative to the conventional approach of an optimum Weiner filter. This algorithm is based on a Gram-Schmidt orthonormalization procedure which is similar to cascade adaptive processing techniques described in earlier works. One of the most desirable features of this type of processing network is that it can be implemented with simple one-stage orthogonal-filter building blocks which directly filter the input data samples. These building blocks are the major subject of this report, and a particular configuration is developed based on a modified version of the familiar Howells-Applebaum algorithm. It can be implemented in either analog or digital form, data storage is not required, it is unconditionally stable, speed of convergence is no longer a problem, and the design is simple. The performance characteristics of a complete orthogonal-lattice-filter network operating in the spacial domain were simulated for example cases of one, two, and three strong incoherent signal sources spaced within a beamwidth for a eight-element linear-array antenna. The adaptive spacial filter patterns and the transient responses demonstrate that the building block has sufficient transient-response speed and control to permit full use of the processing capabilities inherent in a Gram-Schmidt cascade network.

  13. Advances in metabolic pathway and strain engineering paving the way for sustainable production of chemical building blocks.

    PubMed

    Chen, Yun; Nielsen, Jens

    2013-12-01

    Bio-based production of chemical building blocks from renewable resources is an attractive alternative to petroleum-based platform chemicals. Metabolic pathway and strain engineering is the key element in constructing robust microbial chemical factories within the constraints of cost effective production. Here we discuss how the development of computational algorithms, novel modules and methods, omics-based techniques combined with modeling refinement are enabling reduction in development time and thus advance the field of industrial biotechnology. We further discuss how recent technological developments contribute to the development of novel cell factories for the production of the building block chemicals: adipic acid, succinic acid and 3-hydroxypropionic acid.

  14. SRA Real Math Building Blocks PreK. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2007

    2007-01-01

    "SRA Real Math Building Blocks PreK" (also referred to as "Building Blocks for Math") is a supplemental mathematics curriculum designed to develop preschool children's early mathematical knowledge through various individual and small- and large-group activities. It uses "Building Blocks for Math PreK" software,…

  15. High-performance thermoelectric nanocomposites from nanocrystal building blocks

    NASA Astrophysics Data System (ADS)

    Ibáñez, Maria; Luo, Zhishan; Genç, Aziz; Piveteau, Laura; Ortega, Silvia; Cadavid, Doris; Dobrozhan, Oleksandr; Liu, Yu; Nachtegaal, Maarten; Zebarjadi, Mona; Arbiol, Jordi; Kovalenko, Maksym V.; Cabot, Andreu

    2016-03-01

    The efficient conversion between thermal and electrical energy by means of durable, silent and scalable solid-state thermoelectric devices has been a long standing goal. While nanocrystalline materials have already led to substantially higher thermoelectric efficiencies, further improvements are expected to arise from precise chemical engineering of nanoscale building blocks and interfaces. Here we present a simple and versatile bottom-up strategy based on the assembly of colloidal nanocrystals to produce consolidated yet nanostructured thermoelectric materials. In the case study on the PbS-Ag system, Ag nanodomains not only contribute to block phonon propagation, but also provide electrons to the PbS host semiconductor and reduce the PbS intergrain energy barriers for charge transport. Thus, PbS-Ag nanocomposites exhibit reduced thermal conductivities and higher charge carrier concentrations and mobilities than PbS nanomaterial. Such improvements of the material transport properties provide thermoelectric figures of merit up to 1.7 at 850 K.

  16. Monolayer graphene oxide as a building block for artificial muscles

    NASA Astrophysics Data System (ADS)

    Rogers, Geoffrey W.; Liu, Jefferson Z.

    2013-01-01

    The electromechanical actuation of a highly ordered compound of graphene oxide (GO) is shown via ab initio simulations to produce high-performance quantum-mechanical responses, which mimic the behaviour of mammalian skeletal muscle. In addition to large expansive strains (˜10%), this GO compound (asymmetrically unzipped C4O) exhibits large contractive strains of -4.8% upon -0.15 e/C-atom electron injection. Furthermore, as these contractive strains are coupled with equally high stresses (˜100 GPa) and short response times (˜1 ns), we show that this GO material meets all of the functional requirements of an artificial muscle building block.

  17. Optimal control for Rydberg quantum technology building blocks

    NASA Astrophysics Data System (ADS)

    Müller, Matthias M.; Pichler, Thomas; Montangero, Simone; Calarco, Tommaso

    2016-04-01

    We consider a platform for quantum technology based on Rydberg atoms in optical lattices where each atom encodes one qubit of information and external lasers can manipulate their state. We demonstrate how optimal control theory enables the functioning of two specific building blocks on this platform: We engineer an optimal protocol to perform a two-qubit phase gate and to transfer the information within the lattice among specific sites. These two elementary operations allow to design very general operations like storage of atoms and entanglement purification as, for example, needed for quantum repeaters.

  18. Image Chunking: Defining Spatial Building Blocks for Scene Analysis.

    DTIC Science & Technology

    1987-04-01

    mumgs0.USmusa 7.AUWOJO 4. CIUTAC Rm6ANT Wuugme*j James V/. Mlahoney DACA? 6-85-C-00 10 NOQ 1 4-85-K-O 124 Artificial Inteligence Laboratory US USS 545...0197 672 IMAGE CHUWING: DEINING SPATIAL UILDING PLOCKS FOR 142 SCENE ANRLYSIS(U) MASSACHUSETTS INST OF TECH CAIIAIDGE ARTIFICIAL INTELLIGENCE LAO J...Technical Report 980 F-Image Chunking: Defining Spatial Building Blocks for Scene DTm -Analysis S ELECTED James V. Mahoney’ MIT Artificial Intelligence

  19. Fault-tolerant building-block computer study

    NASA Technical Reports Server (NTRS)

    Rennels, D. A.

    1978-01-01

    Ultra-reliable core computers are required for improving the reliability of complex military systems. Such computers can provide reliable fault diagnosis, failure circumvention, and, in some cases serve as an automated repairman for their host systems. A small set of building-block circuits which can be implemented as single very large integration devices, and which can be used with off-the-shelf microprocessors and memories to build self checking computer modules (SCCM) is described. Each SCCM is a microcomputer which is capable of detecting its own faults during normal operation and is described to communicate with other identical modules over one or more Mil Standard 1553A buses. Several SCCMs can be connected into a network with backup spares to provide fault-tolerant operation, i.e. automated recovery from faults. Alternative fault-tolerant SCCM configurations are discussed along with the cost and reliability associated with their implementation.

  20. Plasmonic Metasurfaces with Tailored Linear and Nonlinear Building Blocks

    NASA Astrophysics Data System (ADS)

    Memarzadeh, Babak

    Plasmonic metasurface is an array of sub-wavelength plasmonic particle which is designed to obtain unusual performances by employing the localized surface plasmon (LSP). The dependency of the LSP on the geometry and the material of the plasmonic sub-wavelength particle have opened a wide range of applications for plasmonic metasurfaces. In the first chapter there is brief review of metamaterials and plasmonic metasurfaces. In the second chapter we present the concept of transmitarray concentrator implemented in optics. Planar concentric loop antennas are used as the elements for a 21 x 21 array to concentrate the incident plane wave at a desired distance. Finite difference time domain is used to obtain the performance of the periodic array of each element on the transmitarray and then free space dyadic greens function is employed to find the field distribution at each point, to show the focusing behavior of the metasurface. Third chapter investigates the concept of multi-layered tripod frequency selective surfaces in infrared. A full wave analysis based on finite difference time domain technique is applied to comprehensively characterize the structure and obtain the performance for both normal and oblique waves (for TE and TM polarizations). The layered tripod structure can be envisioned as a mean to realize cascaded LC circuit configurations achieving desired filter performance. A wide stop-band IR nano-filter which is almost independent of incident angle and polarization is demonstrated. Chapter 4 is concentrated on a functional metasurface building block which is multi-material loops. Plasmonic nano loops has been shown to be a capable candidate for creating building blocks of metasurfaces to manipulate the light in desired ways. Concentric loops can couple to each other strongly or weakly based on the relevant designs. The low-coupled multi-material loop metasurface can be employed as a frequency selective surface with number of separated bands. On the other

  1. Energetics of Radical Formation in Eumelanin Building Blocks: Implications for Understanding Photoprotection Mechanisms in Eumelanin.

    PubMed

    Agapito, Filipe; Cabral, Benedito J Costa

    2016-12-22

    The supramolecular structure of melanin pigments is characterized by a high concentration of radical species. Therefore, the energetics of the radical formation in melanin building blocks is key for understanding the structure and the electronic properties of the pigments at the molecular level. Nevertheless, the radical energetics of even the simplest melanin building blocks are largely unknown. In order to address this fundamental issue, the bond dissociation enthalpies (BDEs) for the melanin monomers 5,6-dihydroxy-1H-indole-2-carboxylic acid (DHICA), 1H-indole-5,6-diol (DHI), and 1H-indole-5,6-dione (IQ) were determined through high-accuracy ab initio quantum chemistry methods. Our results provide strong evidence of the importance on BDEs for explaining the experimentally observed dependence of the antioxidant properties of eumelanin pigments on the DHICA/DHI ratio, and the role that these two species play on the photoprotection mechanism.

  2. PUS Services Software Building Block Automatic Generation for Space Missions

    NASA Astrophysics Data System (ADS)

    Candia, S.; Sgaramella, F.; Mele, G.

    2008-08-01

    The Packet Utilization Standard (PUS) has been specified by the European Committee for Space Standardization (ECSS) and issued as ECSS-E-70-41A to define the application-level interface between Ground Segments and Space Segments. The ECSS-E- 70-41A complements the ECSS-E-50 and the Consultative Committee for Space Data Systems (CCSDS) recommendations for packet telemetry and telecommand. The ECSS-E-70-41A characterizes the identified PUS Services from a functional point of view and the ECSS-E-70-31 standard specifies the rules for their mission-specific tailoring. The current on-board software design for a space mission implies the production of several PUS terminals, each providing a specific tailoring of the PUS services. The associated on-board software building blocks are developed independently, leading to very different design choices and implementations even when the mission tailoring requires very similar services (from the Ground operative perspective). In this scenario, the automatic production of the PUS services building blocks for a mission would be a way to optimize the overall mission economy and improve the robusteness and reliability of the on-board software and of the Ground-Space interactions. This paper presents the Space Software Italia (SSI) activities for the development of an integrated environment to support: the PUS services tailoring activity for a specific mission. the mission-specific PUS services configuration. the generation the UML model of the software building block implementing the mission-specific PUS services and the related source code, support documentation (software requirements, software architecture, test plans/procedures, operational manuals), and the TM/TC database. The paper deals with: (a) the project objectives, (b) the tailoring, configuration, and generation process, (c) the description of the environments supporting the process phases, (d) the characterization of the meta-model used for the generation, (e) the

  3. Azobenzene: A Photoactive Building Block for Supramolecular Architectures.

    PubMed

    Baroncini, Massimo; Bergamini, Giacomo

    2017-01-05

    The development of nanoscale systems capable to perform specific functions under external control is a challenging task and a fascinating objective in Chemistry. Photochromic compounds undergo radical changes in their physico-chemical properties upon light excitation, for this reason they are valuable building blocks for the construction of photo-controllable molecular devices, machines and materials. The E-Z photoisomerization of azobenzene has been known for almost 80 years and - owing to its high efficiency and excellent reversibility - has been widely employed to introduce an element of photo-control in a large variety of compounds, biomolecules, nanosystems and materials. Here we present some of our research results highlighting how this outstanding photochrome can be utilized to develop systems with light-induced functionalities.

  4. IMPATT power building blocks for 20 GHz spaceborne transmit amplifier

    NASA Technical Reports Server (NTRS)

    Asmus, J.; Cho, Y.; Degruyl, J.; Ng, E.; Giannakopoulos, A.; Okean, H. C.

    1982-01-01

    Single-stage circulator coupled IMPATT building block constituents of a 20-GHz solid state power amplifier (SSPA) currently under development for spaceborne downlink transmitter usage have been demonstrated as providing 1.5 to 2.0W RF power output at 4 to 5 dB operating gain over a 1 GHz bandwidth. Using either commercially available or recently developed in-house GaAs Schottky Read-profile IMPATT diodes, DC/RF power added efficiencies of 14 to 15% were achieved in these amplifier stages. A two stage IMPATT driver amplifier with similar RF output power capability exhibited 13 + or - 0.5 dB operating gain over a 1 GHz bandwidth.

  5. Linked supramolecular building blocks for enhanced cluster formation

    DOE PAGES

    McLellan, Ross; Palacios, Maria A.; Beavers, Christine M.; ...

    2015-01-09

    Methylene-bridged calix[4]arenes have emerged as extremely versatile ligand supports in the formation of new polymetallic clusters possessing fascinating magnetic properties. Metal ion binding rules established for this building block allow one to partially rationalise the complex assembly process. The ability to covalently link calix[4]arenes at the methylene bridge provides significantly improved control over the introduction of different metal centres to resulting cluster motifs. Clusters assembled from bis-calix[4]arenes and transition metal ions or 3d-4f combinations display characteristic features of the analogous calix[4]arene supported clusters, thereby demonstrating an enhanced and rational approach towards the targeted synthesis of complex and challenging structures.

  6. Linked supramolecular building blocks for enhanced cluster formation

    SciTech Connect

    McLellan, Ross; Palacios, Maria A.; Beavers, Christine M.; Teat, Simon J.; Piligkos, Stergios; Brechin, Euan K.; Dalgarno, Scott J.

    2015-01-09

    Methylene-bridged calix[4]arenes have emerged as extremely versatile ligand supports in the formation of new polymetallic clusters possessing fascinating magnetic properties. Metal ion binding rules established for this building block allow one to partially rationalise the complex assembly process. The ability to covalently link calix[4]arenes at the methylene bridge provides significantly improved control over the introduction of different metal centres to resulting cluster motifs. Clusters assembled from bis-calix[4]arenes and transition metal ions or 3d-4f combinations display characteristic features of the analogous calix[4]arene supported clusters, thereby demonstrating an enhanced and rational approach towards the targeted synthesis of complex and challenging structures.

  7. Network Motifs: Simple Building Blocks of Complex Networks

    NASA Astrophysics Data System (ADS)

    Milo, R.; Shen-Orr, S.; Itzkovitz, S.; Kashtan, N.; Chklovskii, D.; Alon, U.

    2002-10-01

    Complex networks are studied across many fields of science. To uncover their structural design principles, we defined ``network motifs,'' patterns of interconnections occurring in complex networks at numbers that are significantly higher than those in randomized networks. We found such motifs in networks from biochemistry, neurobiology, ecology, and engineering. The motifs shared by ecological food webs were distinct from the motifs shared by the genetic networks of Escherichia coli and Saccharomyces cerevisiae or from those found in the World Wide Web. Similar motifs were found in networks that perform information processing, even though they describe elements as different as biomolecules within a cell and synaptic connections between neurons in Caenorhabditis elegans. Motifs may thus define universal classes of networks. This approach may uncover the basic building blocks of most networks.

  8. Key Building Blocks via Enzyme-Mediated Synthesis

    NASA Astrophysics Data System (ADS)

    Fischer, Thomas; Pietruszka, Jörg

    Biocatalytic approaches to valuable building blocks in organic synthesis have emerged as an important tool in the last few years. While first applications were mainly based on hydrolases, other enzyme classes such as oxidoreductases or lyases moved into the focus of research. Nowadays, a vast number of biotransformations can be found in the chemical and pharmaceutical industries delivering fine chemicals or drugs. The mild reaction conditions, high stereo-, regio-, and chemoselectivities, and the often shortened reaction pathways lead to economical and ecological advantages of enzymatic conversions. Due to the enormous number of enzyme-mediated syntheses, the present chapter is not meant to be a complete review, but to deliver comprehensive insights into well established enzymatic systems and recent advances in the application of enzymes in natural product synthesis. Furthermore, it is focused on the most frequently used enzymes or enzyme classes not covered elsewhere in the present volume.

  9. Nanoporous Gold as a Platform for a Building Block Catalyst

    DOE PAGES

    Wittstock, Arne; Wichmann, Andre; Baeumer, Marcus

    2012-09-25

    The porous bulk materials are of great interest in catalysis because they can be employed in heterogeneous gas and liquid phase catalysis, electrocatalysis, and in electrocatalytic sensing. Nanoporous gold gained considerable attraction in this context because it is the prime example of a corrosion-derived nanoporous bulk metal. Moreover, the material was shown to be a very active and selective Au type catalyst for a variety of oxidation reactions. In leveraging the functionalization of the surface of the material with various additives, its catalytic applications can be extended and tuned. In this review, we will summarize recent developments in using nanoporousmore » gold as the platform for the development of high performance catalytic materials by adding metals, metal oxides, and molecular functionalities as building blocks.« less

  10. Nanoporous Gold as a Platform for a Building Block Catalyst

    SciTech Connect

    Wittstock, Arne; Wichmann, Andre; Baeumer, Marcus

    2012-09-25

    The porous bulk materials are of great interest in catalysis because they can be employed in heterogeneous gas and liquid phase catalysis, electrocatalysis, and in electrocatalytic sensing. Nanoporous gold gained considerable attraction in this context because it is the prime example of a corrosion-derived nanoporous bulk metal. Moreover, the material was shown to be a very active and selective Au type catalyst for a variety of oxidation reactions. In leveraging the functionalization of the surface of the material with various additives, its catalytic applications can be extended and tuned. In this review, we will summarize recent developments in using nanoporous gold as the platform for the development of high performance catalytic materials by adding metals, metal oxides, and molecular functionalities as building blocks.

  11. Hydrotalcite catalysis for the synthesis of new chiral building blocks.

    PubMed

    Rodilla, Jesus M; Neves, Patricia P; Pombal, Sofia; Rives, Vicente; Trujillano, Raquel; Díez, David

    2016-01-01

    The use of hydrotalcites for the synthesis of two chiral building blocks in a simple way is described as a new and green methodology. The synthesis of these compounds implies a regioselective Baeyer-Villiger reaction in a very selective way with ulterior opening and lactonisation. This methodology should be considered green for the use of hydrogen peroxide as the only oxidant and hydrotalcites as the catalyst, and because no residues are produced apart from water. The procedure is very adequate for using in gram scale, in order to increase the value of the obtained compounds. The conditions are excellent and can be applied for nonstable compounds, as they are very mild. The synthesised compounds are magnific starting materials for the synthesis of biologically active or natural compounds. The use of a cheap, commercial and chiral compound as carvone disposable in both enantiomeric forms adds an extra value to this methodology.

  12. Modular assembly of superstructures from polyphenol-functionalized building blocks

    NASA Astrophysics Data System (ADS)

    Guo, Junling; Tardy, Blaise L.; Christofferson, Andrew J.; Dai, Yunlu; Richardson, Joseph J.; Zhu, Wei; Hu, Ming; Ju, Yi; Cui, Jiwei; Dagastine, Raymond R.; Yarovsky, Irene; Caruso, Frank

    2016-12-01

    The organized assembly of particles into superstructures is typically governed by specific molecular interactions or external directing factors associated with the particle building blocks, both of which are particle-dependent. These superstructures are of interest to a variety of fields because of their distinct mechanical, electronic, magnetic and optical properties. Here, we establish a facile route to a diverse range of superstructures based on the polyphenol surface-functionalization of micro- and nanoparticles, nanowires, nanosheets, nanocubes and even cells. This strategy can be used to access a large number of modularly assembled superstructures, including core-satellite, hollow and hierarchically organized supraparticles. Colloidal-probe atomic force microscopy and molecular dynamics simulations provide detailed insights into the role of surface functionalization and how this facilitates superstructure construction. Our work provides a platform for the rapid generation of superstructured assemblies across a wide range of length scales, from nanometres to centimetres.

  13. The building block approach to airborne pod structures

    NASA Astrophysics Data System (ADS)

    Johansson, Jan D.

    2011-05-01

    The certification and testing of new airborne structures is a costly undertaking. This paper presents which measures can be taken to limit the cost and certification required in order to improve the capabilities of the current airborne as-sets, by applying a building block approach to the design and certification of airborne pod structures. A simple way of improving aircraft capabilities is by adding external pod structures, which has been performed for many applications over many years. However, this paper describes a truly modular approach, in which a typical airborne pod structure may be reconfigured to many various roles, with only limited re-certification requirements. Using existing or general aerodynamic shapes, the basic outer shape for the external store is defined, which is then combined with a modular substructure which can accommodate a large variety of electronic and/or optical sensors. This also allows the airborne pod structure to perform several intelligence collecting operations during the same sortie, thereby limiting the time spent near the danger area. The re-use of existing substructure modules reduces the cost and leadtime of the design phase allowing for a rapid entry into service. The modular design, relying on proven interface systems between the building blocks, significantly reduces risk involved in new programs. The certification process is also discussed in order to optimize the use of the pod structure modularity and certification requirements in order to simplify the certification task, by drawing similarity to existing designs. Finally the paper covers how modularity is implemented in new composite pod designs with stealth capabilities.

  14. High-performance thermoelectric nanocomposites from nanocrystal building blocks

    PubMed Central

    Ibáñez, Maria; Luo, Zhishan; Genç, Aziz; Piveteau, Laura; Ortega, Silvia; Cadavid, Doris; Dobrozhan, Oleksandr; Liu, Yu; Nachtegaal, Maarten; Zebarjadi, Mona; Arbiol, Jordi; Kovalenko, Maksym V.; Cabot, Andreu

    2016-01-01

    The efficient conversion between thermal and electrical energy by means of durable, silent and scalable solid-state thermoelectric devices has been a long standing goal. While nanocrystalline materials have already led to substantially higher thermoelectric efficiencies, further improvements are expected to arise from precise chemical engineering of nanoscale building blocks and interfaces. Here we present a simple and versatile bottom–up strategy based on the assembly of colloidal nanocrystals to produce consolidated yet nanostructured thermoelectric materials. In the case study on the PbS–Ag system, Ag nanodomains not only contribute to block phonon propagation, but also provide electrons to the PbS host semiconductor and reduce the PbS intergrain energy barriers for charge transport. Thus, PbS–Ag nanocomposites exhibit reduced thermal conductivities and higher charge carrier concentrations and mobilities than PbS nanomaterial. Such improvements of the material transport properties provide thermoelectric figures of merit up to 1.7 at 850 K. PMID:26948987

  15. Comprehensive Identification and Quantitation of Basic Building Blocks for Low-Molecular Weight Heparin.

    PubMed

    Sun, Xiaojun; Sheng, Anran; Liu, Xinyue; Shi, Feng; Jin, Lan; Xie, Shaoshuai; Zhang, Fuming; Linhardt, Robert J; Chi, Lianli

    2016-08-02

    Low-molecular weight heparins (LMWHs) are widely used anticoagulant drugs. They inherit the heterogeneous backbone sequences of the parent heparin, while the chemical depolymerization process modifies the nonreducing end (NRE) and reducing end (RE) of their sugar chains. Some side reactions may also occur and increase the structural complexity of LMWHs. It is important to precisely characterize the structures of LMWHs, especially their chemical modifications, to ensure drug quality and safety. Compositional analysis provides a powerful approach to reveal the building blocks that make up the LMWHs, which are the mutual consequence of the heparin starting materials and the manufacturing process. Here, we introduce a comprehensive analytical method to recover the most basic building blocks of LMWHs. A strategy of combining both enzymatic digestion and oxidative degradation of LMWH was used to make the NRE, RE, and backbone structures differentiable from one another. Satisfactory separation, identification, and quantitation were achieved by coupling hydrophilic interaction chromatography with a triple quadrupole mass spectrometer operating under the multiple reaction monitoring mode. After enzymatic digestion, over 30 species were detected, with both natural and chemically modified heparin basic building blocks. Two novel structures, including a trisaccharide containing two glucosamine residues and a tetrasaccharide containing a 3-O-sulfated uronic acid residue, were discovered. Reduced and oxidatively degraded samples were analyzed to provide the complementary information on both termini of LMWHs. The reproducibility of this method was evaluated, and enoxaparin injections were analyzed to demonstrate the application of this method for evaluating the sameness of LMWH products.

  16. Identifying the evolutionary building blocks of the cardiac conduction system.

    PubMed

    Jensen, Bjarke; Boukens, Bastiaan J D; Postma, Alex V; Gunst, Quinn D; van den Hoff, Maurice J B; Moorman, Antoon F M; Wang, Tobias; Christoffels, Vincent M

    2012-01-01

    The endothermic state of mammals and birds requires high heart rates to accommodate the high rates of oxygen consumption. These high heart rates are driven by very similar conduction systems consisting of an atrioventricular node that slows the electrical impulse and a His-Purkinje system that efficiently activates the ventricular chambers. While ectothermic vertebrates have similar contraction patterns, they do not possess anatomical evidence for a conduction system. This lack amongst extant ectotherms is surprising because mammals and birds evolved independently from reptile-like ancestors. Using conserved genetic markers, we found that the conduction system design of lizard (Anolis carolinensis and A. sagrei), frog (Xenopus laevis) and zebrafish (Danio rerio) adults is strikingly similar to that of embryos of mammals (mouse Mus musculus, and man) and chicken (Gallus gallus). Thus, in ectothermic adults, the slow conducting atrioventricular canal muscle is present, no fibrous insulating plane is formed, and the spongy ventricle serves the dual purpose of conduction and contraction. Optical mapping showed base-to-apex activation of the ventricles of the ectothermic animals, similar to the activation pattern of mammalian and avian embryonic ventricles and to the His-Purkinje systems of the formed hearts. Mammalian and avian ventricles uniquely develop thick compact walls and septum and, hence, form a discrete ventricular conduction system from the embryonic spongy ventricle. Our study uncovers the evolutionary building plan of heart and indicates that the building blocks of the conduction system of adult ectothermic vertebrates and embryos of endotherms are similar.

  17. Incorporating GIS building data and census housing statistics for sub-block-level population estimation

    USGS Publications Warehouse

    Wu, S.-S.; Wang, L.; Qiu, X.

    2008-01-01

    This article presents a deterministic model for sub-block-level population estimation based on the total building volumes derived from geographic information system (GIS) building data and three census block-level housing statistics. To assess the model, we generated artificial blocks by aggregating census block areas and calculating the respective housing statistics. We then applied the model to estimate populations for sub-artificial-block areas and assessed the estimates with census populations of the areas. Our analyses indicate that the average percent error of population estimation for sub-artificial-block areas is comparable to those for sub-census-block areas of the same size relative to associated blocks. The smaller the sub-block-level areas, the higher the population estimation errors. For example, the average percent error for residential areas is approximately 0.11 percent for 100 percent block areas and 35 percent for 5 percent block areas.

  18. Fault-tolerant computer study. [logic designs for building block circuits

    NASA Technical Reports Server (NTRS)

    Rennels, D. A.; Avizienis, A. A.; Ercegovac, M. D.

    1981-01-01

    A set of building block circuits is described which can be used with commercially available microprocessors and memories to implement fault tolerant distributed computer systems. Each building block circuit is intended for VLSI implementation as a single chip. Several building blocks and associated processor and memory chips form a self checking computer module with self contained input output and interfaces to redundant communications buses. Fault tolerance is achieved by connecting self checking computer modules into a redundant network in which backup buses and computer modules are provided to circumvent failures. The requirements and design methodology which led to the definition of the building block circuits are discussed.

  19. Biorefineries for the production of top building block chemicals and their derivatives.

    PubMed

    Choi, Sol; Song, Chan Woo; Shin, Jae Ho; Lee, Sang Yup

    2015-03-01

    Due to the growing concerns on the climate change and sustainability on petrochemical resources, DOE selected and announced the bio-based top 12 building blocks and discussed the needs for developing biorefinery technologies to replace the current petroleum based industry in 2004. Over the last 10 years after its announcement, many studies have been performed for the development of efficient technologies for the bio-based production of these chemicals and derivatives. Now, ten chemicals among these top 12 chemicals, excluding the l-aspartic acid and 3-hydroxybutyrolactone, have already been commercialized or are close to commercialization. In this paper, we review the current status of biorefinery development for the production of these platform chemicals and their derivatives. In addition, current technological advances on industrial strain development for the production of platform chemicals using micro-organisms will be covered in detail with case studies on succinic acid and 3-hydroxypropionic acid as examples.

  20. Theoretical and technological building blocks for an innovation accelerator

    NASA Astrophysics Data System (ADS)

    van Harmelen, F.; Kampis, G.; Börner, K.; van den Besselaar, P.; Schultes, E.; Goble, C.; Groth, P.; Mons, B.; Anderson, S.; Decker, S.; Hayes, C.; Buecheler, T.; Helbing, D.

    2012-11-01

    Modern science is a main driver of technological innovation. The efficiency of the scientific system is of key importance to ensure the competitiveness of a nation or region. However, the scientific system that we use today was devised centuries ago and is inadequate for our current ICT-based society: the peer review system encourages conservatism, journal publications are monolithic and slow, data is often not available to other scientists, and the independent validation of results is limited. The resulting scientific process is hence slow and sloppy. Building on the Innovation Accelerator paper by Helbing and Balietti [1], this paper takes the initial global vision and reviews the theoretical and technological building blocks that can be used for implementing an innovation (in first place: science) accelerator platform driven by re-imagining the science system. The envisioned platform would rest on four pillars: (i) Redesign the incentive scheme to reduce behavior such as conservatism, herding and hyping; (ii) Advance scientific publications by breaking up the monolithic paper unit and introducing other building blocks such as data, tools, experiment workflows, resources; (iii) Use machine readable semantics for publications, debate structures, provenance etc. in order to include the computer as a partner in the scientific process, and (iv) Build an online platform for collaboration, including a network of trust and reputation among the different types of stakeholders in the scientific system: scientists, educators, funding agencies, policy makers, students and industrial innovators among others. Any such improvements to the scientific system must support the entire scientific process (unlike current tools that chop up the scientific process into disconnected pieces), must facilitate and encourage collaboration and interdisciplinarity (again unlike current tools), must facilitate the inclusion of intelligent computing in the scientific process, must facilitate

  1. Origami building blocks: Generic and special four-vertices

    NASA Astrophysics Data System (ADS)

    Waitukaitis, Scott; van Hecke, Martin

    2016-02-01

    Four rigid panels connected by hinges that meet at a point form a four-vertex, the fundamental building block of origami metamaterials. Most materials designed so far are based on the same four-vertex geometry, and little is known regarding how different geometries affect folding behavior. Here we systematically categorize and analyze the geometries and resulting folding motions of Euclidean four-vertices. Comparing the relative sizes of sector angles, we identify three types of generic vertices and two accompanying subtypes. We determine which folds can fully close and the possible mountain-valley assignments. Next, we consider what occurs when sector angles or sums thereof are set equal, which results in 16 special vertex types. One of these, flat-foldable vertices, has been studied extensively, but we show that a wide variety of qualitatively different folding motions exist for the other 15 special and 3 generic types. Our work establishes a straightforward set of rules for understanding the folding motion of both generic and special four-vertices and serves as a roadmap for designing origami metamaterials.

  2. A generalized locomotion CPG architecture based on oscillatory building blocks.

    PubMed

    Yang, Zhijun; França, Felipe M G

    2003-07-01

    Neural oscillation is one of the most extensively investigated topics of artificial neural networks. Scientific approaches to the functionalities of both natural and artificial intelligences are strongly related to mechanisms underlying oscillatory activities. This paper concerns itself with the assumption of the existence of central pattern generators (CPGs), which are the plausible neural architectures with oscillatory capabilities, and presents a discrete and generalized approach to the functionality of locomotor CPGs of legged animals. Based on scheduling by multiple edge reversal (SMER), a primitive and deterministic distributed algorithm, it is shown how oscillatory building block (OBB) modules can be created and, hence, how OBB-based networks can be formulated as asymmetric Hopfield-like neural networks for the generation of complex coordinated rhythmic patterns observed among pairs of biological motor neurons working during different gait patterns. It is also shown that the resulting Hopfield-like network possesses the property of reproducing the whole spectrum of different gaits intrinsic to the target locomotor CPGs. Although the new approach is not restricted to the understanding of the neurolocomotor system of any particular animal, hexapodal and quadrupedal gait patterns are chosen as illustrations given the wide interest expressed by the ongoing research in the area.

  3. Building Blocks for Reliable Complex Nonlinear Numerical Simulations. Chapter 2

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    This chapter describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations. Examples relevant to turbulent flow computations are included.

  4. Building Blocks for Reliable Complex Nonlinear Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    2005-01-01

    This chapter describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations.

  5. Building Blocks for Reliable Complex Nonlinear Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Mansour, Nagi N. (Technical Monitor)

    2002-01-01

    This talk describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations. Examples relevant to turbulent flow computations are included.

  6. Dispersions of Aramid Nanofibers: A New Nanoscale Building Block

    PubMed Central

    Yang, Ming; Cao, Keqin; Sui, Lang; Qi, Ying; Zhu, Jian; Waas, Anthony; Arruda, Ellen M.; Kieffer, John; Thouless, M. D.; Kotov, Nicholas A.

    2011-01-01

    Stable dispersions of nanofibers are virtually unknown for synthetic polymers. They can complement analogous dispersions of inorganic components, such as nanoparticles, nanowires, nanosheets, etc as a fundamental component of a toolset for design of nanostructures and metamaterials via numerous solvent-based processing methods. As such, strong flexible polymeric nanofibers are very desirable for the effective utilization within composites of nanoscale inorganic components such as nanowires, carbon nanotubes, graphene, and others. Here stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm and up to 10 μm in length were successfully obtained. Unlike the traditional approaches based on polymerization of monomers, they are made by controlled dissolution of standard macroscale form of the aramid polymer, i.e. well known Kevlar threads, and revealed distinct morphological features similar to carbon nanotubes. ANFs are successfully processed into films using layer-by-layer (LBL) assembly as one of the potential methods of preparation of composites from ANFs. The resultant films are transparent and highly temperature resilient. They also display enhanced mechanical characteristics making ANF films highly desirable as protective coatings, ultrastrong membranes, as well as building blocks of other high performance materials in place of or in combination with carbon nanotubes. PMID:21800822

  7. Dispersions of aramid nanofibers: a new nanoscale building block.

    PubMed

    Yang, Ming; Cao, Keqin; Sui, Lang; Qi, Ying; Zhu, Jian; Waas, Anthony; Arruda, Ellen M; Kieffer, John; Thouless, M D; Kotov, Nicholas A

    2011-09-27

    Stable dispersions of nanofibers are virtually unknown for synthetic polymers. They can complement analogous dispersions of inorganic components, such as nanoparticles, nanowires, nanosheets, etc. as a fundamental component of a toolset for design of nanostructures and metamaterials via numerous solvent-based processing methods. As such, strong flexible polymeric nanofibers are very desirable for the effective utilization within composites of nanoscale inorganic components such as nanowires, carbon nanotubes, graphene, and others. Here stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm and up to 10 μm in length were successfully obtained. Unlike the traditional approaches based on polymerization of monomers, they are made by controlled dissolution of standard macroscale form of the aramid polymer, that is, well-known Kevlar threads, and revealed distinct morphological features similar to carbon nanotubes. ANFs are successfully processed into films using layer-by-layer (LBL) assembly as one of the potential methods of preparation of composites from ANFs. The resultant films are transparent and highly temperature resilient. They also display enhanced mechanical characteristics making ANF films highly desirable as protective coatings, ultrastrong membranes, as well as building blocks of other high performance materials in place of or in combination with carbon nanotubes.

  8. Dispersions of Aramid Nanofibers: A New Nanoscale Building Block

    SciTech Connect

    Yang, Ming; Cao, Keqin; Sui, Lang; Qi, Ying; Zhu, Jian; Waas, Anthony; Arruda, Ellen M.; Kieffer, John; Thouless, M. D.; Kotov, Nicholas A.

    2011-09-27

    Stable dispersions of nanofibers are virtually unknown for synthetic polymers. They can complement analogous dispersions of inorganic components, such as nanoparticles, nanowires, nanosheets, etc. as a fundamental component of a toolset for design of nanostructures and metamaterials via numerous solvent-based processing methods. As such, strong flexible polymeric nanofibers are very desirable for the effective utilization within composites of nanoscale inorganic components such as nanowires, carbon nanotubes, graphene, and others. Here stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm and up to 10 μm in length were successfully obtained. Unlike the traditional approaches based on polymerization of monomers, they are made by controlled dissolution of standard macroscale form of the aramid polymer, that is, well-known Kevlar threads, and revealed distinct morphological features similar to carbon nanotubes. ANFs are successfully processed into films using layer-by-layer (LBL) assembly as one of the potential methods of preparation of composites from ANFs. The resultant films are transparent and highly temperature resilient. They also display enhanced mechanical characteristics making ANF films highly desirable as protective coatings, ultrastrong membranes, as well as building blocks of other high performance materials in place of or in combination with carbon nanotubes.

  9. MECs: "Building Blocks" for Creating Biological and Chemical Instruments

    PubMed Central

    Hill, Douglas A.; Anderson, Lindsey E.; Hill, Casey J.; Mostaghim, Afshin; Rodgers, Victor G. J.

    2016-01-01

    The development of new biological and chemical instruments for research and diagnostic applications is often slowed by the cost, specialization, and custom nature of these instruments. New instruments are built from components that are drawn from a host of different disciplines and not designed to integrate together, and once built, an instrument typically performs a limited number of tasks and cannot be easily adapted for new applications. Consequently, the process of inventing new instruments is very inefficient, especially for researchers or clinicians in resource-limited settings. To improve this situation, we propose that a family of standardized multidisciplinary components is needed, a set of “building blocks” that perform a wide array of different tasks and are designed to integrate together. Using these components, scientists, engineers, and clinicians would be able to build custom instruments for their own unique needs quickly and easily. In this work we present the foundation of this set of components, a system we call Multifluidic Evolutionary Components (MECs). “Multifluidic” conveys the wide range of fluid volumes MECs operate upon (from nanoliters to milliliters and beyond); “multi” also reflects the multiple disciplines supported by the system (not only fluidics but also electronics, optics, and mechanics). “Evolutionary” refers to the design principles that enable the library of MEC parts to easily grow and adapt to new applications. Each MEC “building block” performs a fundamental function that is commonly found in biological or chemical instruments, functions like valving, pumping, mixing, controlling, and sensing. Each MEC also has a unique symbol linked to a physical definition, which enables instruments to be designed rapidly and efficiently using schematics. As a proof-of-concept, we use MECs to build a variety of instruments, including a fluidic routing and mixing system capable of manipulating fluid volumes over five

  10. The Development of Spatial Skills through Interventions Involving Block Building Activities

    ERIC Educational Resources Information Center

    Casey, Beth M.; Andrews, Nicole; Schindler, Holly; Kersh, Joanne E.; Samper, Alexandra; Copley, Juanita

    2008-01-01

    This study investigated the use of block-building interventions to develop spatial-reasoning skills in kindergartners. Two intervention conditions and a control condition were included to determine, first, whether the block building activities themselves benefited children's spatial skills, and secondly, whether a story context further improved…

  11. Tailoring Building Blocks and Their Boundary Interaction for the Creation of New, Potentially Superhard, Carbon Materials.

    PubMed

    Yao, Mingguang; Cui, Wen; Du, Mingrun; Xiao, Junping; Yang, Xigui; Liu, Shijie; Liu, Ran; Wang, Fei; Cui, Tian; Sundqvist, Bertil; Liu, Bingbing

    2015-07-08

    A strategy for preparing hybrid carbon structures with amorphous carbon clusters as hard building blocks by compressing a series of predesigned two-component fullerides is presented. In such constructed structures the building blocks and their boundaries can be tuned by changing the starting components, providing a way for the creation of new hard/superhard materials with desirable properties.

  12. Development of Test Article Building Block (TABB) for deployable platform systems

    NASA Technical Reports Server (NTRS)

    Greenberg, H. S.; Barbour, R. T.

    1984-01-01

    The concept of a Test Article Building Block (TABB) is described. The TABB is a ground test article that is representative of a future building block that can be used to construct LEO and GEO deployable space platforms for communications and scientific payloads. This building block contains a main housing within which the entire structure, utilities, and deployment/retraction mechanism are stowed during launch. The end adapter secures the foregoing components to the housing during launch. The main housing and adapter provide the necessary building-block-to-building-block attachments for automatically deployable platforms. Removal from the shuttle cargo bay can be accomplished with the remote manipulator system (RMS) and/or the handling and positioning aid (HAPA). In this concept, all the electrical connections are in place prior to launch with automatic latches for payload attachment provided on either the end adapters or housings. The housings also can contain orbiter docking ports for payload installation and maintenance.

  13. From Synthesis to Function via Iterative Assembly of MIDA Boronate Building Blocks

    PubMed Central

    Li, Junqi; Grillo, Anthony S.; Burke, Martin D.

    2015-01-01

    Small molecules can powerfully benefit society, but the study and optimization of their function is too often impeded by the time-intensive and specialist-dependent process that is typically used to make them. In contrast, general and automated platforms have been developed for peptide, oligonucleotide, and increasingly oligosaccharide synthesis, resulting in on-demand access to these molecules, even for non-specialists. A more generalized and automated approach for making small molecules could similarly help shift the rate limiting step in small molecule science from synthesis to function. Targeting this goal, we have developed a fully automated and increasingly general platform for iterative coupling of boronate building blocks. Analogous to peptide synthesis, the process involves iterative coupling of haloboronic acids protected as the corresponding N-methyliminodiacetic acid (MIDA) boronates. This platform has enabled us and other groups to access many polyene natural products, including the polyene motifs in >75% of all polyene natural products. It further allowed us to derivatize and thereby understand the powerful but also highly toxic antifungal natural product amphotericin B, which has led to the development of less toxic derivatives currently under evaluation as drug candidates. We also discovered a stereocontrolled entry into chiral, non-racemic α-boryl aldehydes, which are versatile intermediates for the synthesis of many Csp3 boronate building blocks that are otherwise difficult to access. We have also expanded the scope of the platform to include Csp3-rich, polycyclic molecules using a linear-to-cyclized strategy, in which Csp3 boronate building blocks are iteratively assembled into linear precursors that are then cyclized into the cyclic frameworks found in many natural products and natural product-like structures. Enabled by the serendipitous discovery of a catch-and-release protocol for generally purifying MIDA boronate intermediates, the platform

  14. Development of a Deterministic Ethernet Building blocks for Space Applications

    NASA Astrophysics Data System (ADS)

    Fidi, C.; Jakovljevic, Mirko

    2015-09-01

    The benefits of using commercially based networking standards and protocols have been widely discussed and are expected to include reduction in overall mission cost, shortened integration and test (I&T) schedules, increased operations flexibility, and hardware and software upgradeability/scalability with developments ongoing in the commercial world. The deterministic Ethernet technology TTEthernet [1] diploid on the NASA Orion spacecraft has demonstrated the use of the TTEthernet technology for a safety critical human space flight application during the Exploration Flight Test 1 (EFT-1). The TTEthernet technology used within the NASA Orion program has been matured for the use within this mission but did not lead to a broader use in space applications or an international space standard. Therefore TTTech has developed a new version which allows to scale the technology for different applications not only the high end missions allowing to decrease the size of the building blocks leading to a reduction of size weight and power enabling the use in smaller applications. TTTech is currently developing a full space products offering for its TTEthernet technology to allow the use in different space applications not restricted to launchers and human spaceflight. A broad space market assessment and the current ESA TRP7594 lead to the development of a space grade TTEthernet controller ASIC based on the ESA qualified Atmel AT1C8RHA95 process [2]. In this paper we will describe our current TTEthernet controller development towards a space qualified network component allowing future spacecrafts to operate in significant radiation environments while using a single onboard network for reliable commanding and data transfer.

  15. The building blocks of the full body ownership illusion

    PubMed Central

    Maselli, Antonella; Slater, Mel

    2013-01-01

    Previous work has reported that it is not difficult to give people the illusion of ownership over an artificial body, providing a powerful tool for the investigation of the neural and cognitive mechanisms underlying body perception and self consciousness. We present an experimental study that uses immersive virtual reality (IVR) focused on identifying the perceptual building blocks of this illusion. We systematically manipulated visuotactile and visual sensorimotor contingencies, visual perspective, and the appearance of the virtual body in order to assess their relative role and mutual interaction. Consistent results from subjective reports and physiological measures showed that a first person perspective over a fake humanoid body is essential for eliciting a body ownership illusion. We found that the illusion of ownership can be generated when the virtual body has a realistic skin tone and spatially substitutes the real body seen from a first person perspective. In this case there is no need for an additional contribution of congruent visuotactile or sensorimotor cues. Additionally, we found that the processing of incongruent perceptual cues can be modulated by the level of the illusion: when the illusion is strong, incongruent cues are not experienced as incorrect. Participants exposed to asynchronous visuotactile stimulation can experience the ownership illusion and perceive touch as originating from an object seen to contact the virtual body. Analogously, when the level of realism of the virtual body is not high enough and/or when there is no spatial overlap between the two bodies, then the contribution of congruent multisensory and/or sensorimotor cues is required for evoking the illusion. On the basis of these results and inspired by findings from neurophysiological recordings in the monkey, we propose a model that accounts for many of the results reported in the literature. PMID:23519597

  16. An Organolanthanide Building Block Approach to Single-Molecule Magnets.

    PubMed

    Harriman, Katie L M; Murugesu, Muralee

    2016-06-21

    and experimental chemistry allows us to shed light on the mechanisms and electronic properties that govern the slow relaxation dynamics inherent to this unique set of SMMs, thus providing insight into the role by which both symmetry and crystal field effects contribute to the magnetic properties. As we look to the future success of such materials in practical devices, we must gain an understanding of how the 4f elements communicate magnetically, a subject upon which there is still limited knowledge. As such, we have described our work on coupling mononuclear metallocenes to generate new dinuclear SMMs. Through a building block approach, we have been able to gain access to new double,- triple- and quadruple-decker complexes that possess remarkable properties; exhibiting TB of 12 K and Ueff above 300 K. Our goal is to develop a fundamental platform from which to study 4f coupling, while maintaining and enhancing the strict axiality of the anisotropy of the 4f ions. This Account will present a successful strategy employed in the production of novel and high-performing SMMs, as well as a clear overview of the lessons learned throughout.

  17. Hierarchical coassembly of DNA-triptycene hybrid molecular building blocks and zinc protoporphyrin IX.

    PubMed

    Kumari, Rina; Singh, Sumit; Monisha, Mohan; Bhowmick, Sourav; Roy, Anindya; Das, Neeladri; Das, Prolay

    2016-01-01

    Herein, we describe the successful construction of composite DNA nanostructures by the self-assembly of complementary symmetrical 2,6,14-triptycenetripropiolic acid (TPA)-DNA building blocks and zinc protoporphyrin IX (Zn PpIX). DNA-organic molecule scaffolds for the composite DNA nanostructure were constructed through covalent conjugation of TPA with 5'-C12-amine-terminated modified single strand DNA (ssDNA) and its complementary strand. The repeated covalent conjugation of TPA with DNA was confirmed by using denaturing polyacrylamide gel electrophoresis (PAGE), reverse-phase high-performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). The biologically relevant photosensitizer Zn PpIX was used to direct the hybridization-mediated self-assembly of DNA-TPA molecular building blocks as well as a model guest molecule within the DNA-TPA supramolecular self-assembly. The formation of fiber-like composite DNA nanostructures was observed. Native PAGE, circular dichroism (CD) and atomic force microscopy (AFM) have been utilized for analyzing the formation of DNA nanofibers after the coassembly. Computational methods were applied to discern the theoretical dimension of the DNA-TPA molecular building block of the nanofibers. A notable change in photocatalytic efficiency of Zn PpIX was observed when it was inside the TPA-DNA scaffold. The significant increase in ROS generation by Zn PpIX when trapped in this biocompatible DNA-TPA hybrid nanofiber may be an effective tool to explore photodynamic therapy (PDT) applications as well as photocatalytic reactions.

  18. The Development of Symbolic Representation: The Case of Building Blocks.

    ERIC Educational Resources Information Center

    Reifel, Stuart

    The symbolic representational block constructions of twenty 4-year-olds and twenty 7-year-olds were analyzed from Werner and Kaplan's (1963) theoretical perspective. Each child was read a story and then asked to use the blocks to represent the story. Older children included in their representations a larger number of features that were central to…

  19. Building a Case for Blocks as Kindergarten Mathematics Learning Tools

    ERIC Educational Resources Information Center

    Kinzer, Cathy; Gerhardt, Kacie; Coca, Nicole

    2016-01-01

    Kindergarteners need access to blocks as thinking tools to develop, model, test, and articulate their mathematical ideas. In the current educational landscape, resources such as blocks are being pushed to the side and being replaced by procedural worksheets and academic "seat time" in order to address standards. Mathematics research…

  20. Modular assembly of primary metabolic building blocks: a chemical language in C. elegans

    PubMed Central

    Schroeder, Frank C.

    2014-01-01

    Summary The metabolome of the nematode Caenorhabditis elegans, like that of other model organisms, remained largely uncharacterized until recent studies demonstrated the importance of small molecule-based signaling cascades for many aspects of nematode biology. These studies revealed that nematodes are amazingly skilled chemists: using simple building blocks from primary metabolism and a strategy of modular assembly, nematodes create complex molecular architectures that serve as signaling molecules. These nematode-derived modular metabolites (NDMMs) are based on the dideoxysugars ascarylose or paratose, which serve as scaffolds for attachment of moieties from lipid, amino acid, neurotransmitter, and nucleoside metabolism. Although preliminary biosynthetic studies have confirmed the primary metabolism origin of some of the building blocks incorporated into NDMMs, the mechanisms that underlie their highly specific assembly are not understood. Overall, I argue that identification of new variants of primary metabolism-derived structures that serve important signaling functions in C. elegans and other nematodes provides a strong incentive for a comprehensive re-analysis of metabolism in higher animals, including humans. PMID:25484238

  1. Modular assembly of primary metabolic building blocks: a chemical language in C. elegans.

    PubMed

    Schroeder, Frank C

    2015-01-22

    The metabolome of the nematode Caenorhabditis elegans, like that of other model organisms, remained largely uncharacterized until recent studies demonstrated the importance of small molecule-based signaling cascades for many aspects of nematode biology. These studies revealed that nematodes are amazingly skilled chemists: using simple building blocks from primary metabolism and a strategy of modular assembly, nematodes create complex molecular architectures that serve as signaling molecules. These nematode-derived modular metabolites (NDMMs) are based on the dideoxysugars ascarylose and paratose, which serve as scaffolds for the attachment of moieties from lipid, amino acid, neurotransmitter, and nucleoside metabolism. Although preliminary biosynthetic studies have confirmed the primary metabolism origin of some of the building blocks incorporated into NDMMs, the mechanisms that underlie their highly specific assembly are not understood. I argue that identification of new variants of primary metabolism-derived structures that serve important signaling functions in C. elegans and other nematodes provides a strong incentive for a comprehensive reanalysis of metabolism in higher animals, including humans.

  2. Mn-based nanostructured building blocks: Synthesis, characterization and applications

    NASA Astrophysics Data System (ADS)

    Beltran Huarac, Juan

    The quest for smaller functional elements of devices has stimulated increased interest in charge-transfer phenomena at the nanoscale. Mn-based nanostructured building blocks are particularly appealing given that the excited states of high-spin Mn2+ ions induce unusual d-d energy transfer processes, which is critical for better understanding the performance of electronic and spintronic devices. These nanostructures also exhibit unique properties superior to those of common Fe- and Co-based nanomaterials, including: excellent structural flexibility, enhanced electrochemical energy storage, effective ion-exchange dynamics, more comprehensive transport mechanisms, strong quantum yield, and they act as effective luminescent centers for more efficient visible light emitters. Moreover, Mn-based nanostructures (MBNs) are crucial for the design and assembly of inexpensive nanodevices in diluted magnetic semiconductors (DMS), optoelectronics, magneto-optics, and field-effect transistors, owing to the great abundance and low-cost of Mn. Nonetheless, the paucity of original methods and techniques to fabricate new multifunctional MBNs that fulfill industrial demands limits the sustainable development of innovative technology in materials sciences. In order to meet this critical need, in this thesis we develop and implement novel methods and techniques to fabricate zero- and one-dimensional highly-crystalline new-generation MBNs conducive to the generation of new technology, and provide alternative and feasible miniaturization strategies to control and devise at nanometric precision their size, shape, structure and composition. Herein, we also establish the experimental conditions to grow Mn-based nanowires (NWs), nanotubes (NTs), nanoribbons (NRs), nanosaws (NSs), nanoparticles (NPs) and nanocomposites (NCs) via chemical/physical deposition and co-precipitation chemical routes, and determine the pertinent arrangements to our experimental schemes in order to extend our bottom

  3. Cosmic "Dig" Reveals Vestiges of the Milky Way's Building Blocks

    NASA Astrophysics Data System (ADS)

    2009-11-01

    Peering through the thick dust clouds of our galaxy's "bulge" (the myriads of stars surrounding its centre), and revealing an amazing amount of detail, a team of astronomers has unveiled an unusual mix of stars in the stellar grouping known as Terzan 5. Never observed anywhere in the bulge before, this peculiar "cocktail" of stars suggests that Terzan 5 is in fact one of the bulge's primordial building blocks, most likely the relic of a proto-galaxy that merged with the Milky Way during its very early days. "The history of the Milky Way is encoded in its oldest fragments, globular clusters and other systems of stars that have witnessed the entire evolution of our galaxy," says Francesco Ferraro from the University of Bologna, lead author of a paper appearing in this week's issue of the journal Nature. "Our study opens a new window on yet another piece of our galactic past." Like archaeologists, who dig through the dust piling up on top of the remains of past civilisations and unearth crucial pieces of the history of mankind, astronomers have been gazing through the thick layers of interstellar dust obscuring the bulge of the Milky Way and have unveiled an extraordinary cosmic relic. The target of the study is the star cluster Terzan 5. The new observations show that this object, unlike all but a few exceptional globular clusters, does not harbour stars which are all born at the same time - what astronomers call a "single population" of stars. Instead, the multitude of glowing stars in Terzan 5 formed in at least two different epochs, the earliest probably some 12 billion years ago and then again 6 billion years ago. "Only one globular cluster with such a complex history of star formation has been observed in the halo of the Milky Way: Omega Centauri," says team member Emanuele Dalessandro. "This is the first time we see this in the bulge." The galactic bulge is the most inaccessible region of our galaxy for astronomical observations: only infrared light can

  4. Plastic Fibre Reinforced Soil Blocks as a Sustainable Building Material

    NASA Astrophysics Data System (ADS)

    Prasad, C. K. Subramania; Nambiar, E. K. Kunhanandan; Abraham, Benny Mathews

    2012-10-01

    Solid waste management, especially the huge quantity of waste plastics, is one of the major environmental concerns nowadays. Their employability in block making in the form of fibres, as one of the methods of waste management, can be investigated through a fundamental research. This paper highlights the salient observations from a systematic investigation on the effect of embedded fibre from plastic waste on the performance of stabilised mud blocks. Stabilisation of the soil was done by adding cement, lime and their combination. Plastic fibre in chopped form from carry bags and mineral water bottles were added (0.1% & 0.2% by weight of soil) as reinforcement. The blocks were tested for density, and compressive strength, and observed failure patterns were analysed. Blocks with 0.1% of plastic fibres showed an increase in strength of about 3 to 10%. From the observations of failure pattern it can be concluded that benefits of fibre reinforcement includes both improved ductility in comparison with raw blocks and inhibition of crack propogation after its initial formation.

  5. Polymorphic Ring-Shaped Molecular Clusters Made of Shape-Variable Building Blocks

    PubMed Central

    Cervantes-Salguero, Keitel; Hamada, Shogo; Nomura, Shin-ichiro M.; Murata, Satoshi

    2015-01-01

    Self-assembling molecular building blocks able to dynamically change their shapes, is a concept that would offer a route to reconfigurable systems. Although simulation studies predict novel properties useful for applications in diverse fields, such kinds of building blocks, have not been implemented thus far with molecules. Here, we report shape-variable building blocks fabricated by DNA self-assembly. Blocks are movable enough to undergo shape transitions along geometrical ranges. Blocks connect to each other and assemble into polymorphic ring-shaped clusters via the stacking of DNA blunt-ends. Reconfiguration of the polymorphic clusters is achieved by the surface diffusion on mica substrate in response to a monovalent salt concentration. This work could inspire novel reconfigurable self-assembling systems for applications in molecular robotics.

  6. Siloxanol-functionalized copper iodide cluster as a thermochromic luminescent building block.

    PubMed

    Perruchas, Sandrine; Desboeufs, Nicolas; Maron, Sébastien; Le Goff, Xavier F; Fargues, Alexandre; Garcia, Alain; Gacoin, Thierry; Boilot, Jean-Pierre

    2012-01-16

    A copper iodide cluster bearing reactive silanol groups exhibits thermochromic luminescence properties sensitive to its chemical environment and is thus a suitable building block for the synthesis of optically active materials.

  7. A Working Model of Protein Synthesis Using Lego(TM) Building Blocks.

    ERIC Educational Resources Information Center

    Templin, Mark A.; Fetters, Marcia K.

    2002-01-01

    Uses Lego building blocks to improve the effectiveness of teaching about protein synthesis. Provides diagrams and pictures for a 2-3 day student activity. Discusses mRNA, transfer RNA, and a protein synthesis model. (MVL)

  8. Real World of Industrial Chemistry: Ethylene: The Organic Chemical Industry's Most Important Building Block.

    ERIC Educational Resources Information Center

    Fernelius, W. Conrad, Ed.; And Others

    1979-01-01

    The value of ethylene, as the organic chemical industry's most important building block, is discussed. The discussion focuses on the source of ethylene, its various forms and functions, and the ways in which the forms are made. (SA)

  9. Building an organic block storage service at CERN with Ceph

    NASA Astrophysics Data System (ADS)

    van der Ster, Daniel; Wiebalck, Arne

    2014-06-01

    Emerging storage requirements, such as the need for block storage for both OpenStack VMs and file services like AFS and NFS, have motivated the development of a generic backend storage service for CERN IT. The goals for such a service include (a) vendor neutrality, (b) horizontal scalability with commodity hardware, (c) fault tolerance at the disk, host, and network levels, and (d) support for geo-replication. Ceph is an attractive option due to its native block device layer RBD which is built upon its scalable, reliable, and performant object storage system, RADOS. It can be considered an "organic" storage solution because of its ability to balance and heal itself while living on an ever-changing set of heterogeneous disk servers. This work will present the outcome of a petabyte-scale test deployment of Ceph by CERN IT. We will first present the architecture and configuration of our cluster, including a summary of best practices learned from the community and discovered internally. Next the results of various functionality and performance tests will be shown: the cluster has been used as a backend block storage system for AFS and NFS servers as well as a large OpenStack cluster at CERN. Finally, we will discuss the next steps and future possibilities for Ceph at CERN.

  10. Designer amphiphilic proteins as building blocks for the intracellular formation of organelle-like compartments.

    PubMed

    Huber, Matthias C; Schreiber, Andreas; von Olshausen, Philipp; Varga, Balázs R; Kretz, Oliver; Joch, Barbara; Barnert, Sabine; Schubert, Rolf; Eimer, Stefan; Kele, Péter; Schiller, Stefan M

    2015-01-01

    Nanoscale biological materials formed by the assembly of defined block-domain proteins control the formation of cellular compartments such as organelles. Here, we introduce an approach to intentionally 'program' the de novo synthesis and self-assembly of genetically encoded amphiphilic proteins to form cellular compartments, or organelles, in Escherichia coli. These proteins serve as building blocks for the formation of artificial compartments in vivo in a similar way to lipid-based organelles. We investigated the formation of these organelles using epifluorescence microscopy, total internal reflection fluorescence microscopy and transmission electron microscopy. The in vivo modification of these protein-based de novo organelles, by means of site-specific incorporation of unnatural amino acids, allows the introduction of artificial chemical functionalities. Co-localization of membrane proteins results in the formation of functionalized artificial organelles combining artificial and natural cellular function. Adding these protein structures to the cellular machinery may have consequences in nanobiotechnology, synthetic biology and materials science, including the constitution of artificial cells and bio-based metamaterials.

  11. Designer amphiphilic proteins as building blocks for the intracellular formation of organelle-like compartments

    NASA Astrophysics Data System (ADS)

    Huber, Matthias C.; Schreiber, Andreas; von Olshausen, Philipp; Varga, Balázs R.; Kretz, Oliver; Joch, Barbara; Barnert, Sabine; Schubert, Rolf; Eimer, Stefan; Kele, Péter; Schiller, Stefan M.

    2015-01-01

    Nanoscale biological materials formed by the assembly of defined block-domain proteins control the formation of cellular compartments such as organelles. Here, we introduce an approach to intentionally ‘program’ the de novo synthesis and self-assembly of genetically encoded amphiphilic proteins to form cellular compartments, or organelles, in Escherichia coli. These proteins serve as building blocks for the formation of artificial compartments in vivo in a similar way to lipid-based organelles. We investigated the formation of these organelles using epifluorescence microscopy, total internal reflection fluorescence microscopy and transmission electron microscopy. The in vivo modification of these protein-based de novo organelles, by means of site-specific incorporation of unnatural amino acids, allows the introduction of artificial chemical functionalities. Co-localization of membrane proteins results in the formation of functionalized artificial organelles combining artificial and natural cellular function. Adding these protein structures to the cellular machinery may have consequences in nanobiotechnology, synthetic biology and materials science, including the constitution of artificial cells and bio-based metamaterials.

  12. The Building Blocks of Life Move from Ground to Tree to Animal and Back to Ground

    NASA Astrophysics Data System (ADS)

    Davidson, E. A.

    2015-12-01

    I generally use combinations of big words to describe my science, such as biogeochemistry, ecosystem ecology, nutrient cycling, stoichiometry, tropical deforestation, land-use change, agricultural intensification, eutrophication, greenhouse gas emissions, and sustainable development. I didn't expect to use any of these words, but I was surprised that I couldn't use some others that seem simple enough to me, such as farm, plant, soil, and forest. I landed on "building blocks" as my metaphor for the forms of carbon, nitrogen, phosphorus, and other elements that I study as they cycle through and among ecosystems. I study what makes trees and other kinds of life grow. We all know that they need the sun and that they take up water from the ground, but what else do trees need from the ground? What do animals that eat leaves and wood get from the trees? Just as we need building blocks to grow our bodies, trees and animals also need building blocks for growing their bodies. Trees get part of their building blocks from the ground and animals get theirs from what they eat. When animals poop and when leaves fall, some of their building blocks return to the ground. When they die, their building blocks also go back to the ground. I also study what happens to the ground, the water, and the air when we cut down trees, kill or shoo away the animals, and make fields to grow our food. Can we grow enough food and still keep the ground, water, and air clean? I think the answer is yes, but it will take better understanding of how all of those building blocks fit together and move around, from ground to tree to animal and back to ground.

  13. Combinatorial chemistry in nematodes: modular assembly of primary metabolism-derived building blocks

    PubMed Central

    2016-01-01

    The nematode Caenorhabditis elegans was the first animal to have its genome fully sequenced and has become an important model organism for biomedical research. However, like many other animal model systems, its metabolome remained largely uncharacterized, until recent investigations demonstrated the importance of small molecule-based signalling cascades for virtually every aspect of nematode biology. These studies have revealed that nematodes are amazingly skilled chemists: using simple building blocks from conserved primary metabolism and a strategy of modular assembly, C. elegans and other nematode species create complex molecular architectures to regulate their development and behaviour. These nematode-derived modular metabolites (NDMMs) are based on the dideoxysugars ascarylose or paratose, which serve as scaffolds for attachment of moieties from lipid, amino acid, carbohydrate, citrate, and nucleoside metabolism. Mutant screens and comparative metabolomics based on NMR spectroscopy and MS have so-far revealed several 100 different ascarylose (“ascarosides”) and a few paratose (“paratosides”) derivatives, many of which represent potent signalling molecules that can be active at femtomolar levels, regulating development, behaviour, body shape, and many other life history traits. NDMM biosynthesis appears to be carefully regulated as assembly of different modules proceeds with very high specificity. Preliminary biosynthetic studies have confirmed the primary metabolism origin of some NDMM building blocks, whereas the mechanisms that underlie their highly specific assembly are not understood. Considering their functions and biosynthetic origin, NDMMs represent a new class of natural products that cannot easily be classified as “primary” or “secondary”. We believe that the identification of new variants of primary metabolism-derived structures that serve important signalling functions in C. elegans and other nematodes provides a strong incentive for

  14. 1,5-Anhydro-D-fructose; a versatile chiral building block: biochemistry and chemistry.

    PubMed

    Andersen, Søren M; Lundt, Inge; Marcussen, Jan; Yu, Shukun

    2002-05-13

    There is a steadily increasing need to expand sustainable resources, and carbohydrates are anticipated to play an important role in this respect, both for bulk and fine chemical preparation. The enzyme alpha-(1-->4)-glucan lyase degrades starch to 1,5-anhydro-D-fructose. This compound, which has three different functional properties, a prochiral center together with a permanent pyran ring, renders it a potential chiral building block for the synthesis of valuable and potentially biologically active compounds. 1,5-Anhydro-D-fructose is found in natural materials as a degradation product of alpha-(1-->4)-glucans. The occurrence of lyases and the metabolism of 1,5-anhydro-D-fructose are reviewed in the biological part of this article. In the chemical part, the elucidated structure of 1,5-anhydro-D-fructose will be presented together with simple stereoselective conversions into hydroxy/amino 1,5-anhydro hexitols and a nojirimycin analogue. Synthesis of 6-O-acylated derivatives of 1,5-anhydro-D-fructose substituted with long fatty acid residues is carried out using commercially available enzymes. Those reactions lead to compounds with potential emulsifying properties. The use of protected derivatives of 1,5-anhydro-D-fructose for the synthesis of natural products is likewise reviewed. The potential utilization of this chemical building block is far from being exhausted. Since 1,5-anhydro-D-fructose now is accessible in larger amounts through a simple-enzyme catalyzed degradation of starch by alpha-(1-->4)-glucan lyase, the application of 1,5-anhydro-D-fructose may be considered a valuable contribution to the utilization of carbohydrates as the most abundant resource of sustainable raw materials.

  15. Biobased building blocks for the rational design of renewable block polymers.

    PubMed

    Holmberg, Angela L; Reno, Kaleigh H; Wool, Richard P; Epps, Thomas H

    2014-10-14

    Block polymers (BPs) derived from biomass (biobased) are necessary components of a sustainable future that relies minimally on petroleum-based plastics for applications ranging from thermoplastic elastomers and pressure-sensitive adhesives to blend compatibilizers. To facilitate their adoption, renewable BPs must be affordable, durable, processable, versatile, and reasonably benign. Their desirability further depends on the relative sustainability of the renewable resources and the methods employed in the monomer and polymer syntheses. Various strategies allow these BPs' characteristics to be tuned and enhanced for commercial applications, and many of these techniques also can be applied to manipulate the wide-ranging mechanical and thermal properties of biobased and self-assembling block polymers. From feedstock to application, this review article highlights promising renewable BPs, plus their material and assembly properties, in support of de novo design strategies that could revolutionize material sustainability.

  16. Binding blocks: building the Universe one nucleus at a time

    NASA Astrophysics Data System (ADS)

    Diget, C. Aa; Pastore, A.; Leech, K.; Haylett, T.; Lock, S.; Sanders, T.; Shelley, M.; Willett, H. V.; Keegans, J.; Sinclair, L.; Simpson, E. C.; the Binding Blocks Collaboration

    2017-03-01

    We present a new teaching and outreach activity based around the construction of a three-dimensional chart of isotopes using \\text{LEG}{{\\text{O}}\\circledR} bricks5. The activity, binding blocks, demonstrates nuclear and astrophysical processes through a seven-meter chart of all nuclear isotopes, built from over 26 000 \\text{LEG}{{\\text{O}}\\circledR} bricks. It integrates A-Level and GCSE curricula across areas of nuclear physics, astrophysics, and chemistry, including: nuclear decays (through the colours in the chart); nuclear binding energy (through tower heights); production of chemical elements in the cosmos; fusion processes in stars and fusion energy on Earth; as well as links to medical physics, particularly diagnostics and radiotherapy.

  17. Building block organisation of clusters in amylopectin from different structural types.

    PubMed

    Bertoft, Eric; Koch, Kristine; Aman, Per

    2012-06-01

    Clusters of chains consisting of tightly branched units of building blocks were isolated from 10 amylopectin samples possessing the 4 types of amylopectin with different internal unit chain profiles previously described. It was shown that clusters in types 1 and 2 amylopectins are larger than in types 3 and 4, but the average cluster size did not correspond to the ratio of short to long chains of the amylopectins. The size-distribution of the building blocks, having one or several branches, possessed generally only small differences between samples. However, the length of the interblock segments followed the type of amylopectin structure, so that type 1 amylopectins had shortest and type 4 the longest segments. The chains in the clusters were divided into characteristic groups probably being involved in the interconnection of two, three, and four - or more - building blocks. Long chains were typically found in high amounts in clusters from type 4 amylopectins, however, all cluster samples contained long chains. The results are discussed in terms of the building block structure of amylopectin, in which the blocks together with the interblock segments participate in a branched backbone building up the amorphous lamellae inside growth rings of the starch granules. In such a model, amylopectins with proportionally less long chains (types 1 and 2) possess a more extensively branched backbone compared to those with more long chains (types 3 and 4).

  18. Piecemeal Buildup of the Genetic Code, Ribosomes, and Genomes from Primordial tRNA Building Blocks

    PubMed Central

    Caetano-Anollés, Derek; Caetano-Anollés, Gustavo

    2016-01-01

    The origin of biomolecular machinery likely centered around an ancient and central molecule capable of interacting with emergent macromolecular complexity. tRNA is the oldest and most central nucleic acid molecule of the cell. Its co-evolutionary interactions with aminoacyl-tRNA synthetase protein enzymes define the specificities of the genetic code and those with the ribosome their accurate biosynthetic interpretation. Phylogenetic approaches that focus on molecular structure allow reconstruction of evolutionary timelines that describe the history of RNA and protein structural domains. Here we review phylogenomic analyses that reconstruct the early history of the synthetase enzymes and the ribosome, their interactions with RNA, and the inception of amino acid charging and codon specificities in tRNA that are responsible for the genetic code. We also trace the age of domains and tRNA onto ancient tRNA homologies that were recently identified in rRNA. Our findings reveal a timeline of recruitment of tRNA building blocks for the formation of a functional ribosome, which holds both the biocatalytic functions of protein biosynthesis and the ability to store genetic memory in primordial RNA genomic templates. PMID:27918435

  19. Semiexperimental equilibrium structures for building blocks of organic and biological molecules: the B2PLYP route.

    PubMed

    Penocchio, Emanuele; Piccardo, Matteo; Barone, Vincenzo

    2015-10-13

    The B2PLYP double hybrid functional, coupled with the correlation-consistent triple-ζ cc-pVTZ (VTZ) basis set, has been validated in the framework of the semiexperimental (SE) approach for deriving accurate equilibrium structures of molecules containing up to 15 atoms. A systematic comparison between new B2PLYP/VTZ results and several equilibrium SE structures previously determined at other levels, in particular B3LYP/SNSD and CCSD(T) with various basis sets, has put in evidence the accuracy and the remarkable stability of such model chemistry for both equilibrium structures and vibrational corrections. New SE equilibrium structures for phenylacetylene, pyruvic acid, peroxyformic acid, and phenyl radical are discussed and compared with literature data. Particular attention has been devoted to the discussion of systems for which lack of sufficient experimental data prevents a complete SE determination. In order to obtain an accurate equilibrium SE structure for these situations, the so-called templating molecule approach is discussed and generalized with respect to our previous work. Important applications are those involving biological building blocks, like uracil and thiouracil. In addition, for more general situations the linear regression approach has been proposed and validated.

  20. Testing the robustness of the genetic algorithm on the floating building block representation

    SciTech Connect

    Lindsay, R.K.; Wu, A.S.

    1996-12-31

    Recent studies on a floating building block representation for the genetic algorithm (GA) suggest that there are many advantages to using the floating representation. This paper investigates the behavior of the GA on floating representation problems in response to three different types of pressures: (1) a reduction in the amount of genetic material available to the GA during the problem solving process, (2) functions which have negative-valued building blocks, and (3) randomizing non-coding segments. Results indicate that the GA`s performance on floating representation problems is very robust. Significant reductions in genetic material (genome length) may be made with relatively small decrease in performance. The GA can effectively solve problems with negative building blocks. Randomizing non-coding segments appears to improve rather than harm GA performance.

  1. Building blocks X-FAB SOI 0.18 μm

    NASA Astrophysics Data System (ADS)

    Cizel, J.-B.; Ahmad, S.; Callier, S.; Cornat, R.; Dulucq, F.; Fleury, J.; Martin-Chassard, G.; Raux, L.; de La Taille, C.; Thienpont, D.

    2015-02-01

    This work has been done in order to study a new technology provided by X-FAB named xt018. It is an SOI (Silicon On Insulator) technology with a minimal gate length of 180 nm. Building blocks have been done to test the advantages and drawbacks of this technology compared to the one currently used (AMS SiGe 0.35 μm). These building blocks have been designed to fit in an existing experience housed by the CALICE collaboration: the read-out chip for the Electromagnetic CALorimeter (ECAL) of the foreseen International Linear Collider (ILC). Performances will be compared to those of the SKIROC2 chip designed by the OMEGA laboratory, trying to fit the same requirements. The chip is being manufactured and will be back for measurements in December, the displayed results are only simulation results and thus the conclusions concerning the performances of these building blocks are subject to change.

  2. A general strategy for self-assembly of nanosized building blocks on liquid/liquid interfaces.

    PubMed

    Liu, Jian-Wei; Zhang, Shao-Yi; Qi, Hao; Wen, Wu-Cheng; Yu, Shu-Hong

    2012-08-06

    A family of water/oil interfaces is introduced to provide effective platforms for rapid fabrication of large-area self-assembled nanofilms composed of various nanosized building blocks, including nanoparticles (NPs), nanocubes (NC), nanowires (NWs), and nanosheets, at room temperature. As a general interfacial assembly method, NWs and NPs are co-assembled at the liquid/liquid interface. The as-prepared co-assembled Ag NW and Ag NC films show high surface-enhanced Raman spectroscopy (SERS) intensity, the SERS performance being strongly dependent on the number ratio of the two kinds of nanosized building blocks. The results demonstrate that this interfacial system provides a general method for the assembly of various nanosized building blocks with different shapes and dimensionalities, and thus paves an alternative pathway for further applications of macroscopic assemblies with different functionalities.

  3. Wrapping cytochrome c around single-wall carbon nanotube: engineered nanohybrid building blocks for infrared detection at high quantum efficiency.

    PubMed

    Gong, Youpin; Liu, Qingfeng; Wilt, Jamie Samantha; Gong, Maogang; Ren, Shenqiang; Wu, Judy

    2015-06-11

    Biomolecule cytochrome c (Cty c), a small molecule of a chain of amino acids with extraordinary electron transport, was helically wrapped around a semiconductive single-wall carbon nanotube (s-SWCNT) to form a molecular building block for uncooled infrared detection with two uniquely designed functionalities: exciton dissociation to free charge carriers at the heterojunction formed on the s-SWCNT/Cty c interface and charge transport along the electron conducting chain of Cty c (acceptor) and hole conducting channel through s-SWCNT (donor). Such a design aims at addressing the long-standing challenges in exciton dissociation and charge transport in an SWCNT network, which have bottlenecked development of photonic SWCNT-based infrared detectors. Using these building blocks, uncooled s-SWCNT/Cyt c thin film infrared detectors were synthesized and shown to have extraordinary photoresponsivity up to 0.77 A W(-1) due to a high external quantum efficiency (EQE) in exceeding 90%, which represents a more than two orders of magnitude enhancement than the best previously reported on CNT-based infrared detectors with EQE of only 1.72%. From a broad perspective, this work on novel s-SWCNT/Cyt c nanohybrid infrared detectors has developed a successful platform of engineered carbon nanotube/biomolecule building blocks with superior properties for optoelectronic applications.

  4. Constructing functional mesostructured materials from colloidal nanocrystal building blocks.

    PubMed

    Milliron, Delia J; Buonsanti, Raffaella; Llordes, Anna; Helms, Brett A

    2014-01-21

    tin-doped indium oxide (ITO) NCs. These dramatic effects emerge from reconstruction of the inorganic glass immediately adjacent to the NC interface. When co-assembling NCs with block copolymers, direct coordination of the polymer to NC surfaces again opens new opportunities for functional mesoscale constructs. We strip NCs of their native ligands and design block copolymers containing a NC tethering domain that bonds strongly, yet dynamically, to the resulting open coordination sites. This strategy enables their co-assembly at high volume fractions of NCs and leads to well-ordered mesoporous NC networks. We find these architectures to be exceptionally stable under chemical transformations driven by cation insertion, removal, and exchange. These developments offer a modular toolbox for arranging NCs deliberately with respect to heterogeneous elements and open space. We have control over metrics that define such architectures from the atomic scale (bonding and crystal structure) through the mesoscale (crystallite shapes and sizes and pore dimensions). By tuning these parameters and better understanding the interactions between components, we look forward to boundless opportunities to employ mesoscale structure, in tandem with composition, to develop functional materials.

  5. Final Technical Report - Commercially Important Carbohydrate Diacids - Building Blocks from Renewable Carbohydrates

    SciTech Connect

    Kiely, Donald E.

    2009-01-07

    The primary objective of this project was to develop oxidation methods appropriate for the conversion of agriculturally derived simple sugars to their corresponding diacids (aldaric acids) for use as biobased chemical building blocks for new biodegradable polymers and other materials. Principal target diacids were D-glucaric, meso-xylaric, D-mannaric and L-arabinaric acid, each to be prepared by nitric acid oxidation of the naturally occurring precursor carbohydrates (monosaccharides) D-glucose, D-xylose, D-mannose and L-arabinose, respectively, all from hydrolysis of naturally abundant plant polysaccharides. These conversions were to be designed for scale up to a level suitable for transfer first to a pilot plant scale, and then to an industrial plant scale. The core of the project involved a comprehensive study of the title oxidation employing a computer controlled reactor. The plan of action involved defining experimental parameters to allow for control of the oxidations with considerable precision and reproducibility. The prototype oxidations were typically run using ca. 0.75 molar amounts of carbohydrate, with a goal of eventually doubling the reaction size when appropriate reaction parameters were established. During the course of the funding period for this grant, the fundamentals of reaction control were established for oxidation of D-glucose, a critical component of the project given the exothermic character of the reaction. The reactions were monitored using a reliable GC/MS protocol. The glucose to glucaric acid conversion represented the most important and potentially highest value conversion. During the grant period we were able to establish one workable system to carry out the glucose to glucaric acid conversion, but were not able to optimize the process or establish a protocol that was satisfactory for a scale up to a pilot plant scale. However, the work carried out showed the possibility that with appropriate innovation and continued effort, a

  6. Utilization of methylarenes as versatile building blocks in organic synthesis.

    PubMed

    Vanjari, Rajeshwer; Singh, Krishna Nand

    2015-11-21

    The development of practical and efficient methods for C-C and C-X bond formation has attracted a great deal of current attention with the advent of C-H functionalization reactions. Hydrocarbons are perhaps the most inexpensive and readily available materials, and utilisation of such materials for the synthesis of essential chemicals is virtually and economically pragmatic. The means to utilize easily accessible hydrocarbons not only represents a useful, potent and straightforward alternative, but also constitutes an excellent opportunity to improve our chemical knowledge about a relatively unexplored domain. Early examples using alkylarenes are generally limited to their conversion to aldehydes, carboxylic acids, and nitriles. This review intends to focus on the latest developments adopting modern strategies for sp(3) C-H functionalization of methylarenes to achieve a diverse range of important organic compounds.

  7. Characterization of an Indole-3-Acetamide Hydrolase from Alcaligenes faecalis subsp. parafaecalis and Its Application in Efficient Preparation of Both Enantiomers of Chiral Building Block 2,3-Dihydro-1,4-Benzodioxin-2-Carboxylic Acid.

    PubMed

    Mishra, Pradeep; Kaur, Suneet; Sharma, Amar Nath; Jolly, Ravinder S

    2016-01-01

    Both the enantiomers of 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid are valuable chiral synthons for enantiospecific synthesis of therapeutic agents such as (S)-doxazosin mesylate, WB 4101, MKC 242, 2,3-dihydro-2-hydroxymethyl-1,4-benzodioxin, and N-[2,4-oxo-1,3-thiazolidin-3-yl]-2,3-dihydro-1,4-benzodioxin-2-carboxamide. Pharmaceutical applications require these enantiomers in optically pure form. However, currently available methods suffer from one drawback or other, such as low efficiency, uncommon and not so easily accessible chiral resolving agent and less than optimal enantiomeric purity. Our interest in finding a biocatalyst for efficient production of enantiomerically pure 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid lead us to discover an amidase activity from Alcaligenes faecalis subsp. parafaecalis, which was able to kinetically resolve 2,3-dihydro-1,4-benzodioxin-2-carboxyamide with E value of >200. Thus, at about 50% conversion, (R)-2,3-dihydro-1,4-benzodioxin-2-carboxylic acid was produced in >99% e.e. The remaining amide had (S)-configuration and 99% e.e. The amide and acid were easily separated by aqueous (alkaline)-organic two phase extraction method. The same amidase was able to catalyse, albeit at much lower rate the hydrolysis of (S)-amide to (S)-acid without loss of e.e. The amidase activity was identified as indole-3-acetamide hydrolase (IaaH). IaaH is known to catalyse conversion of indole-3-acetamide (IAM) to indole-3-acetic acid (IAA), which is phytohormone of auxin class and is widespread among plants and bacteria that inhabit plant rhizosphere. IaaH exhibited high activity for 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which was about 65% compared to its natural substrate, indole-3-acetamide. The natural substrate for IaaH indole-3-acetamide shared, at least in part a similar bicyclic structure with 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which may account for high activity of enzyme towards this un-natural substrate. To the best of

  8. Characterization of an Indole-3-Acetamide Hydrolase from Alcaligenes faecalis subsp. parafaecalis and Its Application in Efficient Preparation of Both Enantiomers of Chiral Building Block 2,3-Dihydro-1,4-Benzodioxin-2-Carboxylic Acid

    PubMed Central

    Mishra, Pradeep; Kaur, Suneet; Sharma, Amar Nath; Jolly, Ravinder S.

    2016-01-01

    Both the enantiomers of 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid are valuable chiral synthons for enantiospecific synthesis of therapeutic agents such as (S)-doxazosin mesylate, WB 4101, MKC 242, 2,3-dihydro-2-hydroxymethyl-1,4-benzodioxin, and N-[2,4-oxo-1,3-thiazolidin-3-yl]-2,3-dihydro-1,4-benzodioxin-2-carboxamide. Pharmaceutical applications require these enantiomers in optically pure form. However, currently available methods suffer from one drawback or other, such as low efficiency, uncommon and not so easily accessible chiral resolving agent and less than optimal enantiomeric purity. Our interest in finding a biocatalyst for efficient production of enantiomerically pure 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid lead us to discover an amidase activity from Alcaligenes faecalis subsp. parafaecalis, which was able to kinetically resolve 2,3-dihydro-1,4-benzodioxin-2-carboxyamide with E value of >200. Thus, at about 50% conversion, (R)-2,3-dihydro-1,4-benzodioxin-2-carboxylic acid was produced in >99% e.e. The remaining amide had (S)-configuration and 99% e.e. The amide and acid were easily separated by aqueous (alkaline)-organic two phase extraction method. The same amidase was able to catalyse, albeit at much lower rate the hydrolysis of (S)-amide to (S)-acid without loss of e.e. The amidase activity was identified as indole-3-acetamide hydrolase (IaaH). IaaH is known to catalyse conversion of indole-3-acetamide (IAM) to indole-3-acetic acid (IAA), which is phytohormone of auxin class and is widespread among plants and bacteria that inhabit plant rhizosphere. IaaH exhibited high activity for 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which was about 65% compared to its natural substrate, indole-3-acetamide. The natural substrate for IaaH indole-3-acetamide shared, at least in part a similar bicyclic structure with 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which may account for high activity of enzyme towards this un-natural substrate. To the best of

  9. LEGO® Bricks as Building Blocks for Centimeter-Scale Biological Environments: The Case of Plants

    PubMed Central

    Lind, Kara R.; Sizmur, Tom; Benomar, Saida; Miller, Anthony; Cademartiri, Ludovico

    2014-01-01

    LEGO bricks are commercially available interlocking pieces of plastic that are conventionally used as toys. We describe their use to build engineered environments for cm-scale biological systems, in particular plant roots. Specifically, we take advantage of the unique modularity of these building blocks to create inexpensive, transparent, reconfigurable, and highly scalable environments for plant growth in which structural obstacles and chemical gradients can be precisely engineered to mimic soil. PMID:24963716

  10. Identification of candidate molecules for the building blocks of life's earliest polymers

    NASA Astrophysics Data System (ADS)

    Hud, Nicholas

    2016-07-01

    Chemists have yet to find a plausible prebiotic route to RNA polymers, and most proposed mechanisms for prebiotic peptide synthesis are inefficient. We are exploring the hypothesis that RNA and peptides have both evolved from polymers with different chemical structures. We have found that molecules closely related to amino acids and the nucleobases of RNA, which were likely present on the prebiotic Earth, greatly facilitate the formation of polypeptides and RNA-like structures (Chen et al., 2014; Forsythe et al., 2015). The identification of molecules that may have served as precursors to the building blocks of extant polymers, or as prebiotic catalysts for biopolymer formation, has direct implications regarding which molecules that should be considered as possible signs of chemistries that can support the emergence of life in the universe. Furthermore, the possibility that life started with molecules that can be repeatedly cycled between their monomeric and polymeric states, as is still the case with extant biopolymers, suggests environmental characteristics that would have facilitated the formation and early evolution of functional biopolymers (Walker et al., 2012). M. C. Chen, et al., J. Am. Chem. Soc., 2014, 136, 5640-5646 J. G. Forsythe, et al., Angew. Chem., Int. Ed. Engl., 2015, 54, 9871-9875. M.A. Walker, et al., PLoS ONE, 2012, 7, e34166.

  11. Markov model-based polymer assembly from force field-parameterized building blocks

    NASA Astrophysics Data System (ADS)

    Durmaz, Vedat

    2015-03-01

    A conventional by hand construction and parameterization of a polymer model for the purpose of molecular simulations can quickly become very work-intensive and time-consuming. Using the example of polyglycerol, I present a polymer decompostion strategy yielding a set of five monomeric residues that are convenient for an instantaneous assembly and subsequent force field simulation of a polyglycerol polymer model. Force field parameters have been developed in accordance with the classical Amber force field. Partial charges of each unit were fitted to the electrostatic potential using quantum-chemical methods and slightly modified in order to guarantee a neutral total polymer charge. In contrast to similarly constructed models of amino acid and nucleotide sequences, the glycerol building blocks may yield an arbitrary degree of bifurcations depending on the underlying probabilistic model. The iterative development of the overall structure as well as the relation of linear to branching units is controlled by a simple Markov model which is presented with few algorithmic details. The resulting polymer is highly suitable for classical explicit water molecular dynamics simulations on the atomistic level after a structural relaxation step. Moreover, the decomposition strategy presented here can easily be adopted to many other (co)polymers.

  12. "Looking through the Eyes of the Learner": Implementation of Building Blocks for Student Engagement

    ERIC Educational Resources Information Center

    D'Annolfo, Suzanne Cordier; Schumann, Jeffrey A.

    2012-01-01

    The Building Blocks for Student Engagement (BBSE) protocol was designed to provide a consistent framework of common language and a visual point of reference shared among students, teachers and school leaders to keep a laser-like focus on the instructional core and student engagement. Grounded in brain-based learning and implemented in urban,…

  13. Trainer's Guide to Building Blocks for Teaching Preschoolers with Special Needs [CD-ROM

    ERIC Educational Resources Information Center

    Joseph, Gail E.; Sandall, Susan R.; Schwartz, Ilene S.

    2010-01-01

    An essential teaching companion for instructors of pre-K educators, this convenient CD-ROM is a vivid blueprint for effective inclusive education using the popular "Building Blocks" approach. Following the structure of the bestselling textbook, this comprehensive guide helps teacher educators provide effective instruction on the three types of…

  14. Public Opinion on Youth, Crime and Race: A Guide for Advocates. Building Blocks for Youth.

    ERIC Educational Resources Information Center

    Soler, Mark

    This guide summarizes public opinion research on youth and juvenile justice issues from the Building Blocks for Youth focus groups and various national polls. Overall, the public is less fearful about crime than in the past but believes juvenile crime is increasing. There is serious public concern about the effectiveness of the juvenile justice…

  15. HOT CELL BUILDING, TRA632. ELEVATIONS. PUMICE BLOCK WALLS. BLOWER AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    HOT CELL BUILDING, TRA-632. ELEVATIONS. PUMICE BLOCK WALLS. BLOWER AND FILTER LOFT PLATFORM AND LADDER ON EAST SIDE. IDAHO OPERATIONS OFFICE MTR-632-IDO-4, 11/1952. INL INDEX NO. 531-0632-00-396-110563, REV. 2. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  16. CONTROL HOUSE, TRA620. MASONS ERECT PUMICE BLOCK WALLS. BUILDING WILL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTROL HOUSE, TRA-620. MASONS ERECT PUMICE BLOCK WALLS. BUILDING WILL CONTROL ACCESS TO MTR AND OTHER "HOT" AND CLASSIFIED AREAS. INL NEGATIVE NO. 577. Unknown Photographer, 9/11/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  17. MTR STACK, TRA71, DETAIL OF PUMICE BLOCK SERVICE BUILDING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MTR STACK, TRA-71-, DETAIL OF PUMICE BLOCK SERVICE BUILDING AT BASE OF STACK. CAMERA FACING SOUTHEAST. INL NEGATIVE NO. HD52-1-2. Mike Crane, Photographer, 5/2005 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  18. Effects of a Preschool Mathematics Curriculum: Summative Research on the "Building Blocks" Project

    ERIC Educational Resources Information Center

    Clements, Douglas H.; Sarama, Julie

    2007-01-01

    This study evaluated the efficacy of a preschool mathematics program based on a comprehensive model of developing research-based software and print curricula. Building Blocks, funded by the National Science Foundation, is a curriculum development project focused on creating research-based, technology-enhanced mathematics materials for pre-K…

  19. PBF Reactor Building (PER620). Detail of arrangement of highdensity blocks ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PBF Reactor Building (PER-620). Detail of arrangement of high-density blocks and other basement shielding. Date: February 1966. Ebasco Services 1205 PER/PBF 620-A-7. INEEL index no. 761-0620-00-205-123070 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  20. Atomic structure and handedness of the building block of a biological assembly.

    PubMed

    Loquet, Antoine; Habenstein, Birgit; Chevelkov, Veniamin; Vasa, Suresh Kumar; Giller, Karin; Becker, Stefan; Lange, Adam

    2013-12-26

    Noncovalent supramolecular assemblies possess in general several unique subunit-subunit interfaces.The basic building block of such an assembly consists of several subunits and contains all unique interfaces. Atomic-resolution structures of monomeric subunits are typically accessed by crystallography or solution NMR and fitted into electron microscopy density maps. However, the structure of the intact building block in the assembled state remains unknown with this hybrid approach. Here, we present the solid-state NMR atomic structure of the building block of the type III secretion system needle. The building block structure consists of a homotetrameric subunit complex with three unique supramolecular interfaces. Side-chain positions at the interfaces were solved at atomic detail. The high-resolution structure reveals unambiguously the helical handedness of the assembly, determined to be right-handed for the type III secretion system needle.Additionally, the axial rise per subunit could be extracted from the tetramer structure and independently validated by mass-per-length measurements.

  1. Sequence-Defined Oligomers from Hydroxyproline Building Blocks for Parallel Synthesis Applications.

    PubMed

    Kanasty, Rosemary L; Vegas, Arturo J; Ceo, Luke M; Maier, Martin; Charisse, Klaus; Nair, Jayaprakash K; Langer, Robert; Anderson, Daniel G

    2016-08-08

    The functionality of natural biopolymers has inspired significant effort to develop sequence-defined synthetic polymers for applications including molecular recognition, self-assembly, and catalysis. Conjugation of synthetic materials to biomacromolecules has played an increasingly important role in drug delivery and biomaterials. We developed a controlled synthesis of novel oligomers from hydroxyproline-based building blocks and conjugated these materials to siRNA. Hydroxyproline-based monomers enable the incorporation of broad structural diversity into defined polymer chains. Using a perfluorocarbon purification handle, we were able to purify diverse oligomers through a single solid-phase extraction method. The efficiency of synthesis was demonstrated by building 14 unique trimers and 4 hexamers from 6 diverse building blocks. We then adapted this method to the parallel synthesis of hundreds of materials in 96-well plates. This strategy provides a platform for the screening of libraries of modified biomolecules.

  2. Transportable Payload Operations Control Center reusable software: Building blocks for quality ground data systems

    NASA Technical Reports Server (NTRS)

    Mahmot, Ron; Koslosky, John T.; Beach, Edward; Schwarz, Barbara

    1994-01-01

    The Mission Operations Division (MOD) at Goddard Space Flight Center builds Mission Operations Centers which are used by Flight Operations Teams to monitor and control satellites. Reducing system life cycle costs through software reuse has always been a priority of the MOD. The MOD's Transportable Payload Operations Control Center development team established an extensive library of 14 subsystems with over 100,000 delivered source instructions of reusable, generic software components. Nine TPOCC-based control centers to date support 11 satellites and achieved an average software reuse level of more than 75 percent. This paper shares experiences of how the TPOCC building blocks were developed and how building block developer's, mission development teams, and users are all part of the process.

  3. Hierarchical assembly of extended coordination networks constructed by novel metallacalix[4]arenes building blocks.

    PubMed

    Li, Xia; Wu, Benlai; Wang, Ruiying; Zhang, Hongyun; Niu, Caoyuan; Niu, Yunyin; Hou, Hongwei

    2010-03-15

    Five interesting metal-organic nanostructures and networks, [Ni(4)(HL)(4)(bpy)(py)(H(2)O)(5)](2) x 0.5 H(2)O (1), [Co(4)(HL)(4)(bpy)(py)(H(2)O)(5)](2) x 0.5 H(2)O (2), [Ni(4)(HL)(4)(H(2)O)(7)](n) x nH(2)O (3), [Ni(4)(HL)(4)(bpy)(2)(H(2)O)(4)](n) (4), and [Cd(4)(HL)(4)(H(2)O)](n) (5), were synthesized hydrothermally [H(3)L = 2-(pyridin-2-yl)-1H-imidazole-4,5-dicarboxylate acid, py = pyridine, and bpy = 4,4'-bipyridine]. Intriguingly, all compounds consist of novel metallacalix[4]arene building blocks M(4)(HL)(4), where doubly deprotonated HL in the same bichelating fashion of mu-kN,N':kO,N'' displays a strong coordination orientation by cooperation of the 4,5-imidazoledicarboxylate and 2-pyridyl groups. Very interestingly, the symmetry of M(4)(HL)(4) and the linkage styles between metal nodes and HL in M(4)(HL)(4) are sensitive to the reaction conditions, and the resulting structural motifs vary with secondary ligands and metal nodes. In 1 and 2, two C(1)-symmetric M(4)(HL)(4) units are bpy-bridged into dimeric chiral nanomolecules with two different cavities. As deprotonated with NaOH, the combination of Ni(II) and HL forms a pseudo-S(4)- or S(4)-symmetric M(4)(HL)(4), which further assembles into 1D chiral crystals 3 or rare 3D crystals 4 of bpy-bridged 5-fold interpenetrating diamondoid architecture with metallacalix[4]arene building blocks as novel 4-connecting nodes, and the combination of Cd(II) and HL forms an 8-connected C(2)-symmetric M(4)(HL)(4) that fabricates the alpha-Po net of 5. Notably, those large M(4)(HL)(4) units are potentially highly connected building blocks in a hierarchical assembly of metal-organic networks. Magnetic studies disclose antiferromagnetic interactions in M(4)(HL)(4) of 1-4. The magnetic data for 1, 3, and 4, all containing isomeric Ni(4)(HL)(4) units, are analyzed by an equilateral quadrangle isotropic model combined with the molecular-field approximation with J = -4.00(2), -3.39(2), and -2.72(3) cm(-1), respectively, presenting

  4. Interlocking Toy Building Blocks as Hands-On Learning Modules for Blind and Visually Impaired Chemistry Students

    ERIC Educational Resources Information Center

    Melaku, Samuel; Schreck, James O.; Griffin, Kameron; Dabke, Rajeev B.

    2016-01-01

    Interlocking toy building blocks (e.g., Lego) as chemistry learning modules for blind and visually impaired (BVI) students in high school and undergraduate introductory or general chemistry courses are presented. Building blocks were assembled on a baseplate to depict the relative changes in the periodic properties of elements. Modules depicting…

  5. Efficient Risk Determination of Risk of Road Blocking by Means of MMS and Data of Buildings and Their Surrounding

    NASA Astrophysics Data System (ADS)

    Nose, Kazuhito; Hatake, Shuhei

    2016-06-01

    Massive earthquake named "Tonankai Massive earthquake" is predicted to occur in the near future and is feared to cause severe damage in Kinki District . "Hanshin-Awaji Massive Earthquake" in 1995 destroyed most of the buildings constructed before 1981 and not complying with the latest earthquake resistance standards. Collapsed buildings blocked roads, obstructed evacuation, rescue and firefighting operations and inflicted further damages.To alleviate the damages, it is important to predict the points where collapsed buildings are likely block the roads and to take precautions in advance. But big cities have an expanse of urban areas with densely-distributed buildings, and it requires time and cost to check each and every building whether or not it will block the road. In order to reduce blocked roads when a disaster strikes, we made a study and confirmed that the risk of road blocking can be determined easily by means of the latest technologies of survey and geographical information.

  6. Coarse-Grained Simulations of the Self-Assembly of DNA-Linked Gold Nanoparticle Building Blocks

    NASA Astrophysics Data System (ADS)

    Armistead, Charles

    The self-assembly of nanoparticles (NPs) of varying shape, size, and composition for the purpose of constructing useful nanoassemblies with tailored properties remains challenging. Although progress has been made to design anisotropic building blocks that exhibit the required control for the precise placement of various NPs within a defined arrangement, there still exists obstacles in the technology to maximize the programmability in the self-assembly of NP building blocks. Currently, the self-assembly of nanostructures involves much experimental trial and error. Computational modeling is a possible approach that could be utilized to facilitate the purposeful design of the self-assembly of NP building blocks into a desired nanostructure. In this report, a coarse-grained model of NP building blocks based on an effective anisotropic mono-functionalization approach, which has shown the ability to construct six building block configurations, was used to simulate various nanoassemblies. The purpose of the study was to validate the model's ability to simulate the self-assembly of the NP building blocks into nanostructures previously produced experimentally. The model can be programmed to designate up to six oligonucleotides attached to the surface of a Au NP building block, with a modifiable length and nucleotide sequence. The model successfully simulated the self-assembly of Au NP building blocks into a number of previously produced nanostructures and demonstrated the ability to produce visualizations of self-assembly as well as calculate interparticle distances and angles to be used for the comparison with the previous experimental data for validation of the model. Also, the model was used to simulate nanoassemblies which had not been produced experimentally for its further validation. The simulations showed the capability of the model to use specific NP building blocks and self-assemble. The coarse-grained NP building block model shows promise as a tool to complement

  7. Preparation of [18F]-N-(2-fluoro-ethyl)-N-methylamine as a building block for PET radiopharmaceuticals.

    PubMed

    Hoareau, Raphael; Gobbi, Luca; Grall-Ulsemer, Sandra; Martarello, Laurent

    2014-11-01

    We have investigated the use of cyclic sulfamidates as precursors to yield secondary amines as building blocks for subsequent reaction with carboxylic acids and acyl chlorides. The preparation of the protonated form of [(18)F]-N-(2-fluoro-ethyl)-N-methylamine from the corresponding cyclic sulfamidate proceeded within a one pot two-step procedure (81 ± 12%, n = 10). The secondary amine reacted readily with acyl chlorides and/or carboxylic acids giving amides with yields ranging from 4 to 17% at the end of synthesis (182 ± 12 min). The new methodology provides a practical approach for the labelling of molecules where intramolecular cyclisation of precursors is favoured under typical radiofluorination conditions.

  8. Study of DNA coated nanoparticles as possible programmable self-assembly building blocks

    NASA Astrophysics Data System (ADS)

    Högberg, Björn; Helmersson, Jing; Holm, Svante; Olin, Håkan

    2006-05-01

    Nanoparticles coated with single stranded DNA have been shown to efficiently hybridize to targets of complementary DNA. This property might be used to implement programmable (or algorithmic) self-assembly to build nanoparticle structures. However, we argue that a DNA coated nanoparticle by itself cannot be used as a programmable self-assembly building block since it does not have directed bonds. A general scheme for assembling and purifying nanoparticle eight-mers with eight geometrically well-directed bonds is presented together with some preliminary experimental work.

  9. Identification of Biomolecular Building Blocks by Recognition Tunneling: Stride towards Nanopore Sequencing of Biomolecules

    NASA Astrophysics Data System (ADS)

    Sen, Suman

    DNA, RNA and Protein are three pivotal biomolecules in human and other organisms, playing decisive roles in functionality, appearance, diseases development and other physiological phenomena. Hence, sequencing of these biomolecules acquires the prime interest in the scientific community. Single molecular identification of their building blocks can be done by a technique called Recognition Tunneling (RT) based on Scanning Tunneling Microscope (STM). A single layer of specially designed recognition molecule is attached to the STM electrodes, which trap the targeted molecules (DNA nucleoside monophosphates, RNA nucleoside monophosphates or amino acids) inside the STM nanogap. Depending on their different binding interactions with the recognition molecules, the analyte molecules generate stochastic signal trains accommodating their "electronic fingerprints". Signal features are used to detect the molecules using a machine learning algorithm and different molecules can be identified with significantly high accuracy. This, in turn, paves the way for rapid, economical nanopore sequencing platform, overcoming the drawbacks of Next Generation Sequencing (NGS) techniques. To read DNA nucleotides with high accuracy in an STM tunnel junction a series of nitrogen-based heterocycles were designed and examined to check their capabilities to interact with naturally occurring DNA nucleotides by hydrogen bonding in the tunnel junction. These recognition molecules are Benzimidazole, Imidazole, Triazole and Pyrrole. Benzimidazole proved to be best among them showing DNA nucleotide classification accuracy close to 99%. Also, Imidazole reader can read an abasic monophosphate (AP), a product from depurination or depyrimidination that occurs 10,000 times per human cell per day. In another study, I have investigated a new universal reader, 1-(2-mercaptoethyl)pyrene (Pyrene reader) based on stacking interactions, which should be more specific to the canonical DNA nucleosides. In addition

  10. Hierarchical assembly of micro-/nano-building blocks: bio-inspired rigid structural functional materials.

    PubMed

    Yao, Hong-Bin; Fang, Hai-Yu; Wang, Xiao-Han; Yu, Shu-Hong

    2011-07-01

    The huge diversity of hierarchical micro-/nano-rigid structures existing in biological systems is increasingly becoming a source of inspiration of materials scientists and engineers to create next-generation advanced functional materials. In the past decades, these multiscale hierarchical structures have been intensively investigated to show their contributions to high performance in mechanical properties. Recently, accompanied with the development of nanotechnology, some biologically hierarchical rigid structures have been duplicated and mimicked in artificial materials through hierarchical organization of micro-/nano-building blocks. In this critical review, we will present biological rigid structural models, functional micro-/nano-building blocks, and hierarchical assembly techniques for the manufacture of bio-inspired rigid structural functional materials (177 references).

  11. Toward Controlled Hierarchical Heterogeneities in Giant Molecules with Precisely Arranged Nano Building Blocks

    PubMed Central

    2016-01-01

    Herein we introduce a unique synthetic methodology to prepare a library of giant molecules with multiple, precisely arranged nano building blocks, and illustrate the influence of minute structural differences on their self-assembly behaviors. The T8 polyhedral oligomeric silsesquioxane (POSS) nanoparticles are orthogonally functionalized and sequentially attached onto the end of a hydrophobic polymer chain in either linear or branched configuration. The heterogeneity of primary chemical structure in terms of composition, surface functionality, sequence, and topology can be precisely controlled and is reflected in the self-assembled supramolecular structures of these giant molecules in the condensed state. This strategy offers promising opportunities to manipulate the hierarchical heterogeneities of giant molecules via precise and modular assemblies of various nano building blocks. PMID:27163025

  12. Dendrimers and Dendrons as Versatile Building Blocks for the Fabrication of Functional Hydrogels.

    PubMed

    Kaga, Sadik; Arslan, Mehmet; Sanyal, Rana; Sanyal, Amitav

    2016-04-15

    Hydrogels have emerged as a versatile class of polymeric materials with a wide range of applications in biomedical sciences. The judicious choice of hydrogel precursors allows one to introduce the necessary attributes to these materials that dictate their performance towards intended applications. Traditionally, hydrogels were fabricated using either polymerization of monomers or through crosslinking of polymers. In recent years, dendrimers and dendrons have been employed as well-defined building blocks in these materials. The multivalent and multifunctional nature of dendritic constructs offers advantages in either formulation or the physical and chemical properties of the obtained hydrogels. This review highlights various approaches utilized for the fabrication of hydrogels using well-defined dendrimers, dendrons and their polymeric conjugates. Examples from recent literature are chosen to illustrate the wide variety of hydrogels that have been designed using dendrimer- and dendron-based building blocks for applications, such as sensing, drug delivery and tissue engineering.

  13. Programming Colloidal Crystal Habit with Anisotropic Nanoparticle Building Blocks and DNA Bonds.

    PubMed

    O'Brien, Matthew N; Lin, Hai-Xin; Girard, Martin; Olvera de la Cruz, Monica; Mirkin, Chad A

    2016-11-09

    Colloidal crystallization can be programmed using building blocks consisting of a nanoparticle core and DNA bonds to form materials with controlled crystal symmetry, lattice parameters, stoichiometry, and dimensionality. Despite this diversity of colloidal crystal structures, only spherical nanoparticles crystallized with BCC symmetry experimentally yield single crystals with well-defined crystal habits. Here, we use low-symmetry, anisotropic nanoparticles to overcome this limitation and to access single crystals with different equilibrium Wulff shapes: a cubic habit from cube-shaped nanoparticles, a rhombic dodecahedron habit from octahedron-shaped nanoparticles, and an octahedron habit from rhombic dodecahedron-shaped nanoparticles. The observation that one can control the microscopic shape of single crystals based upon control of particle building block and crystal symmetry has important fundamental and technological implications for this novel class of colloidal matter.

  14. Microfluidic assembly kit based on laser-cut building blocks for education and fast prototyping

    PubMed Central

    Gerber, Lukas C.; Kim, Honesty; Riedel-Kruse, Ingmar H.

    2015-01-01

    Here, we present an inexpensive rapid-prototyping method that allows researchers and children to quickly assemble multi-layered microfluidic devices from easily pre-fabricated building blocks. We developed low-cost (<$2) kits based on laser-cut acrylic building block pieces and double-sided tape that allow users to generate water droplets in oil, capture living cells, and conduct basic phototaxis experiments. We developed and tested a 90-min lesson plan with children aged 12–14 yr and provide here the instructions for teachers to replicate these experiments and lessons. All parts of the kit are easy to make or order. We propose to use such easy to fabricate kits in labs with no access to current microfluidic tools as well as in classroom environments to get exposure to the powerful techniques of microfluidics. PMID:26634013

  15. Plasmid vectors and molecular building blocks for the development of genetic manipulation tools for Trypanosoma cruzi.

    PubMed

    Bouvier, León A; Cámara, María de los Milagros; Canepa, Gaspar E; Miranda, Mariana R; Pereira, Claudio A

    2013-01-01

    The post genomic era revealed the need for developing better performing, easier to use and more sophisticated genetic manipulation tools for the study of Trypanosoma cruzi, the etiological agent of Chagas disease. In this work a series of plasmids that allow genetic manipulation of this protozoan parasite were developed. First of all we focused on useful tools to establish selection strategies for different strains and which can be employed as expression vectors. On the other hand molecular building blocks in the form of diverse selectable markers, modifiable fluorescent protein and epitope-tag coding sequences were produced. Both types of modules were harboured in backbone molecules conceived to offer multiple construction and sub-cloning strategies. These can be used to confer new properties to already available genetic manipulation tools or as starting points for whole novel designs. The performance of each plasmid and building block was determined independently. For illustration purposes, some simple direct practical applications were conducted.

  16. Optimal allocation of building blocks between nutrient uptake systems in a microbe.

    PubMed

    van den Berg, Hugo A; Kiselev, Yuri N; Orlov, Michael V

    2002-03-01

    A bacterial cell must distribute its molecular building blocks among various types of nutrient uptake systems. If the microbe is to maximize its average growth rate, this allocation of building blocks must be adjusted to the environmental availabilities of the various nutrients. The adjustments can be found from growth balancing considerations. We give a full proof of optimality and uniqueness of the optimal allocation regime for a simple model of microbial growth and internal stores kinetics. This proof suggests likely candidates for optimal control regimes in the case of a more realistic model. These candidate regimes differ with respect to the information that the cell's control system must have access to. We pay particular attention to one of the three candidates, a feedback regime based on a cellular control system that monitors only internal reserve densities. We show that allocation converges rapidly to balanced growth under this control regime.

  17. Microfluidic assembly kit based on laser-cut building blocks for education and fast prototyping.

    PubMed

    Gerber, Lukas C; Kim, Honesty; Riedel-Kruse, Ingmar H

    2015-11-01

    Here, we present an inexpensive rapid-prototyping method that allows researchers and children to quickly assemble multi-layered microfluidic devices from easily pre-fabricated building blocks. We developed low-cost (<$2) kits based on laser-cut acrylic building block pieces and double-sided tape that allow users to generate water droplets in oil, capture living cells, and conduct basic phototaxis experiments. We developed and tested a 90-min lesson plan with children aged 12-14 yr and provide here the instructions for teachers to replicate these experiments and lessons. All parts of the kit are easy to make or order. We propose to use such easy to fabricate kits in labs with no access to current microfluidic tools as well as in classroom environments to get exposure to the powerful techniques of microfluidics.

  18. Discrete Rectangles, Prisms, and Heterometallic Cages from a Conjugated Cp*Rh-Based Building Block.

    PubMed

    Shen, Xu-Yu; Zhang, Ying-Ying; Zhang, Long; Lin, Yue-Jian; Jin, Guo-Xin

    2015-11-16

    By carefully selecting an existing synthetic strategy and suitable coordination subunits, constructing desired coordination geometries is no longer that difficult to accomplish. Herein, a new strategy to construct a series of unprecedented structures by using conjugated Cp*Rh-based complex BN-OTf (Cp* = η(5)-C5Me5) as the building block is proposed. DFT calculations revealed extensive delocalized π bonds in the subunit. With BN-OTf, rectangular macrocycles TN-bpy and TN-bpe were controllably synthesized. Single-crystal XRD studies confirmed one-dimensional stacking channels for the tetranuclear structure. Notably, the starting ligand imidazole-4,5-dicarboxylate was found to act not only as a tetradentate but also as a hexadentate ligand that can coordinate to further metal ions. Subsequently, [4 Rh+1 M] heterometallic complexes HMZ (M = Cu and Zn) were accessed by chelating borderline hard/soft Lewis acids. With TN-Linker or HMZ, two routes resulted in the [8 Rh+2 M] heterometallic cages HMC (M = Cu and Zn) with excellent crystallinity and stability. Surprisingly, when BN-OTf bonded to rhodium itself, triangular prisms TP-Linker were obtained with high solubility after being linked by bipyridine linkers. Both the X-ray structure and (1)H NMR spectrum confirmed the novel isomerization of the triangular structures. All of the compounds were obtained in high yields and were fully characterized by (1)H NMR spectroscopy, elemental analysis, IR spectroscopy, and in most cases single-crystal X-ray structure determination.

  19. A study of standard building blocks for the design of fault-tolerant distributed computer systems

    NASA Technical Reports Server (NTRS)

    Rennels, D. A.; Avizienis, A.; Ercegovac, M.

    1978-01-01

    This paper presents the results of a study that has established a standard set of four semiconductor VLSI building-block circuits. These circuits can be assembled with off-the-shelf microprocessors and semiconductor memory modules into fault-tolerant distributed computer configurations. The resulting multi-computer architecture uses self-checking computer modules backed up by a limited number of spares. A redundant bus system is employed for communication between computer modules.

  20. PBF Reactor Building (PER620). After lowering reactor vessel onto blocks, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PBF Reactor Building (PER-620). After lowering reactor vessel onto blocks, it is rolled on logs into PBF. Metal framework under vessel is handling device. Various penetrations in reactor bottom were for instrumentation, poison injection, drains. Large one, below center "manhole" was for primary coolant. Photographer: Larry Page. Date: February 13, 1970. INEEL negative no. 70-736 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  1. High-Performance Photovoltaic Polymers Employing Symmetry-Breaking Building Blocks.

    PubMed

    Liu, Deyu; Zhu, Qianqian; Gu, Chunyang; Wang, Junyi; Qiu, Meng; Chen, Weichao; Bao, Xichang; Sun, Mingliang; Yang, Renqiang

    2016-10-01

    Two 1D-2D asymmetric benzodithiophenes (BDTs) as donor building blocks are designed and synthesized, combining the advantages of both 1D and 2D symmetric BDTs. The photovoltaic properties of the asymmetric BDT-based polymers are improved greatly in comparison with corresponding symmetric BDT-based polymers. This work provides a new approach to design prospective organic optoelectronic materials employing the symmetry-breaking strategy.

  2. Functional Perfluoroalkyl Polyhedral Oligomeric Silsesquioxane (F-POSS): Building Blocks for Low Surface Energy Materials

    DTIC Science & Technology

    2010-10-21

    low-surface energy material for superhydrophobic and oleophobic surfaces. These F-POSS compounds consist of a silicon-oxide core with a periphery of...for the development of new superhydrophobic and oleophobic materials. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...F·I’OSS. These no\\e1 structures can he used as the initial building blocks for the development of Ilew superhydrophobic and o!cophobic materials

  3. Surface grafted polymer brushes as ideal building blocks for "smart" surfaces.

    PubMed

    Zhou, Feng; Huck, Wilhelm T S

    2006-09-07

    Polymer brushes are assemblies of macromolecules chemically tethered at one end to a substrate. They provide an alternative to self-assembled monolayers because of the intrinsically large size of the building blocks and the ensuing entropic contribution to the film morphology. In this article, an overview of a number of representative polymer brush systems will be presented and their potential application for surfaces with controlled wettability, smart surfaces and nanoactuators will be explored in some detail.

  4. A new tetracyclic lactam building block for thick, broad-bandgap photovoltaics.

    PubMed

    Kroon, Renee; Diaz de Zerio Mendaza, Amaia; Himmelberger, Scott; Bergqvist, Jonas; Bäcke, Olof; Faria, Gregório Couto; Gao, Feng; Obaid, Abdulmalik; Zhuang, Wenliu; Gedefaw, Desta; Olsson, Eva; Inganäs, Olle; Salleo, Alberto; Müller, Christian; Andersson, Mats R

    2014-08-20

    A new tetracyclic lactam building block for polymer semiconductors is reported that was designed to combine the many favorable properties that larger fused and/or amide-containing building blocks can induce, including improved solid-state packing, high charge carrier mobility, and improved charge separation. Copolymerization with thiophene resulted in a semicrystalline conjugated polymer, PTNT, with a broad bandgap of 2.2 eV. Grazing incidence wide-angle X-ray scattering of PTNT thin films revealed a strong tendency for face-on π-stacking of the polymer backbone, which was retained in PTNT:fullerene blends. Corresponding solar cells featured a high open-circuit voltage of 0.9 V, a fill factor around 0.6, and a power conversion efficiency as high as 5% for >200 nm thick active layers, regardless of variations in blend stoichiometry and nanostructure. Moreover, efficiencies of >4% could be retained when thick active layers of ∼400 nm were employed. Overall, these values are the highest reported for a conjugated polymer with such a broad bandgap and are unprecedented in materials for tandem and particularly ternary blend photovoltaics. Hence, the newly developed tetracyclic lactam unit has significant potential as a conjugated building block in future organic electronic materials.

  5. Technological characteristics of compressed earth blocks for its use as a building material

    NASA Astrophysics Data System (ADS)

    Gomez-Villalba, Luz Stella; Camacho-Perez, Nancy; Alvarez de Buergo, Monica; Becerra-Becerra, Javier; Esmeralda Corredor-Pulido, Dery; Fort, Rafael

    2013-04-01

    We present here an innovative building technique, which uses ecological, inexpensive and environmentally friendly materials. These compressed earth blocks seem to be very good for building purposes and that is why we have characterized three types of compressed earth blocks (CEB, named by their color as yellow, grey and red) mineralogically by means of X ray diffraction XRD and scanning electron microscopy SEM (both blocks and raw materials), petrographically by polarizing optical light microscopy POLM, and SEM, and, mainly, petrophysically: their hydric, physical and physico-mechanical properties by means of determining their capillary water absorption, porosity (open or accessible to water, pore size distribution and micro/macroporosity), and densities, color and ultrasound velocity (together with anisotropy). The particularities of these analyzed materials show that some varieties are more durable than others, and that all of them can be used as building materials with some restrictions related to their appropriate placing in the structures and the exposure to water. Acknowledgements: This work is supported by the GEOMATERIALES (S2009/MAT-1629) and CONSOLIDER-TCP (CSD2007-0058) programmes. Thanks also to the UCM (Complutense University of Madrid) Research Group "Alteración y conservación de los materiales pétreos del patrimonio" / Alteration and conservation of heritage stone materials (ref. 921349).

  6. Geospatial-enabled Data Exploration and Computation through Data Infrastructure Building Blocks

    NASA Astrophysics Data System (ADS)

    Song, C. X.; Biehl, L. L.; Merwade, V.; Villoria, N.

    2015-12-01

    Geospatial data are present everywhere today with the proliferation of location-aware computing devices and sensors. This is especially true in the scientific community where large amounts of data are driving research and education activities in many domains. Collaboration over geospatial data, for example, in modeling, data analysis and visualization, must still overcome the barriers of specialized software and expertise among other challenges. The GABBs project aims at enabling broader access to geospatial data exploration and computation by developing spatial data infrastructure building blocks that leverage capabilities of end-to-end application service and virtualized computing framework in HUBzero. Funded by NSF Data Infrastructure Building Blocks (DIBBS) initiative, GABBs provides a geospatial data architecture that integrates spatial data management, mapping and visualization and will make it available as open source. The outcome of the project will enable users to rapidly create tools and share geospatial data and tools on the web for interactive exploration of data without requiring significant software development skills, GIS expertise or IT administrative privileges. This presentation will describe the development of geospatial data infrastructure building blocks and the scientific use cases that help drive the software development, as well as seek feedback from the user communities.

  7. Reference Architecture Test-Bed for Avionics (RASTA): A Software Building Blocks Overview

    NASA Astrophysics Data System (ADS)

    Viana Sanchez, Aitor; Taylor, Chris

    2010-08-01

    This paper presents an overview of the Reference Architecture System Test-bed for Avionics (RASTA) being developed within the ESA Estec Data Systems Division. This activity aims to benefit from interface standardization to provide a hardware/software reference infrastructure into which incoming R&D activities can be integrated, thus providing a generic but standardized test and development environment rather than dedicated facilities for each activity. Rasta is composed of by both HW and SW building blocks constituting the main elements of a typical Data Handling System. This includes a core processor (LEON2), Telemetry and Telecommand links, digital interfaces, and mass memory. The range of digital serial interfaces includes CAN bus, MIL-STD-1553 and SpaceWire. The paper will focus on the Software aspects of RASTA and in particular the software building blocks provided to ease development activities and allow hardware independency. To support the take-up of RASTA by European Industry, all RASTA software developed internally by ESA is provided free under license. Significant outputs are already available and include: Basic SW and SW drivers (CAN/1553/SpW, TT&C), OS abstraction layer, CFDP flight implementation, highly portable and independent file system for space, ground segment telecommand/telemetry router. In the future, additional SW building blocks are planned (e.g. ECSS CAN library). The present focus of RASTA is related to a prototype implementation of the SOIS services and protocols under development by the CCSDS (Consultative committee for Space Data Standards)

  8. The building blocks for JWST I&T to operations: from simulator to flight units

    NASA Astrophysics Data System (ADS)

    Wasiak, Francis; Ochs, William; Johns, Alan; Seaton, Bonita; Adams, Cynthia; Fatig, Curtis; Jones, Ronald; Jackson, Wallace

    2012-09-01

    The James Webb Space Telescope (JWST) Project has an extended integration and test (I&T) phase due to long procurement and development times of various components as well as recent launch delays. The JWST Ground Segment and Operations group has developed a roadmap of the various ground and flight elements and their use in the various JWST I&T test programs. The JWST Project's building block approach to the eventual operational systems, while not new, is complex and challenging; a large-scale mission like JWST involves international partners, many vendors across the United States, and competing needs for the same systems. One of the challenges is resource balancing so simulators and flight products for various elements congeal into integrated systems used for I&T and flight operations activities. This building block approach to an incremental buildup provides for early problem identification with simulators and exercises the flight operations systems, products, and interfaces during the JWST I&T test programs. The JWST Project has completed some early I&T with the simulators, engineering models and some components of the operational ground system. The JWST Project is testing the various flight units as they are delivered and will continue to do so for the entire flight and operational system. The JWST Project has already and will continue to reap the value of the building block approach on the road to launch and flight operations.

  9. Development of a building block design of modular photovoltaic concentrator array fields

    SciTech Connect

    Carmichael, D.C.; Alexander, G.; Noel, G.T.; Scurlock, L.D.; Huss, W.R.; Stickford, G.H.

    1983-08-01

    To reduce the balance-of-system (BOS) costs and site-specific design costs for photovoltaic concentrator array fields, a modular Building Block design has been developed for installing array fields of each of two available concentrator collectors. The array-field subsystems and requirements incorporated in the design analyses include site preparation, foundations, electrical wiring, grounding, lightning protection, electromagnetic interference provisions, and tracking and controls. The Building Block designs developed minimize these array-field BOS costs and serve as standardized units to be used in multiples to construct array fields of various sizes. The detailed drawings and construction specifications prepared for the designs require only minimal design modification and cost for adaption to a specific site and application. The two concentrator collectors for which the modular array-field designs were developed are the linear-focus Fresnel-lens array manufactured by E-Systems, Inc., and the point-focus Fresnel-lens array manufactured by Martin Marietta Aerospace Corporation. Both designs are two-axis tracking and passively cooled. The developed Building Block designs are immediately applicable and reduce the array-field BOS costs and site-specific design costs to a fraction of those experienced in previous installations. The estimated array-field BOS costs (in 1982 dollars) using these modular designs are $0.78/W for the modular field based on the E-Systems array and $1.18/W for the modular field based on the Martin-Marietta array.

  10. {Quantification of Colloidal Blocking by Humic Acids in Porous Media

    NASA Astrophysics Data System (ADS)

    Yang, X.; Flynn, R.; von der Kammer, F.; Hofmann, T.

    2009-04-01

    colloid response in these latter experiments suggested that 1μg of SRHA could block 4.51x106 colloidal deposition sites. At molecular level, this means that 9.6 x107 SRHA molecules block one colloidal deposition site, assuming number average molecular weight of SRHA of 1390g/mol. Study results further highlight the potential of humic acids to promote the transport of natural and anthropogenic substances in groundwater.

  11. Niflumic acid blocks native and recombinant T-type channels.

    PubMed

    Balderas, Enrique; Ateaga-Tlecuitl, Rogelio; Rivera, Manuel; Gomora, Juan C; Darszon, Alberto

    2012-06-01

    Voltage-dependent calcium channels are widely distributed in animal cells, including spermatozoa. Calcium is fundamental in many sperm functions such as: motility, capacitation, and the acrosome reaction (AR), all essential for fertilization. Pharmacological evidence has suggested T-type calcium channels participate in the AR. Niflumic acid (NA), a non-steroidal anti-inflammatory drug commonly used as chloride channel blocker, blocks T-currents in mouse spermatogenic cells and Cl(-) channels in testicular sperm. Here we examine the mechanism of NA blockade and explore if it can be used to separate the contribution of different Ca(V)3 members previously detected in these cells. Electrophysiological patch-clamp recordings were performed in isolated mouse spermatogenic cells and in HEK cells heterologously expressing Ca(V)3 channels. NA blocks mouse spermatogenic cell T-type currents with an IC(50) of 73.5 µM, without major voltage-dependent effects. The NA blockade is more potent in the open and in the inactivated state than in the closed state of the T-type channels. Interestingly, we found that heterologously expressed Ca(V)3.1 and Ca(V)3.3 channels were more sensitive to NA than Ca(V)3.2 channels, and this drug substantially slowed the recovery from inactivation of the three isoforms. Molecular docking modeling of drug-channel binding predicts that NA binds preferentially to the extracellular face of Ca(V)3.1 channels. The biophysical characteristics of mouse spermatogenic cell T-type currents more closely resemble those from heterologously expressed Ca(V)3.1 channels, including their sensitivity to NA. As Ca(V)3.1 null mice maintain their spermatogenic cell T-currents, it is likely that a novel Ca(V)3.2 isoform is responsible for them.

  12. NIFLUMIC ACID BLOCKS NATIVE AND RECOMBINANT T-TYPE CHANNELS

    PubMed Central

    Balderas, E; Arteaga-Tlecuitl, R; Rivera, M; Gomora, JC; Darszon, A

    2012-01-01

    Voltage-dependent calcium channels are widely distributed in animal cells, including spermatozoa. Calcium is fundamental in many sperm functions such as: motility, capacitation and the acrosome reaction, all essential for fertilization. Pharmacological evidence has suggested T-type calcium channels participate in the acrosome reaction. Niflumic acid (NA), a non-steroidal anti-inflammatory drug commonly used as chloride channel blocker, blocks T-currents in mouse spermatogenic cells and Cl− channels in testicular sperm. Here we examine the mechanism of NA blockade and explore if it can be used to separate the contribution of different CaV3 members previously detected in these cells. Electrophysiological patch-clamp recordings were performed in isolated mouse spermatogenic cells and in HEK cells heterologously expressing CaV3 channels. NA blocks mouse spermatogenic cell T-type currents with an IC50 of 73.5 µM, without major voltage-dependent effects. The NA blockade is more potent in the open and in the inactivated state than in the closed state of the T-type channels. Interestingly, we found that heterologously expressed CaV3.1 and CaV3.3 channels were more sensitive to NA than CaV3.2 channels, and this drug substantially slowed the recovery from inactivation of the three isoforms. Molecular docking modeling of drug-channel binding predicts that NA binds preferentially to the extracellular face of CaV3.1 channels. The biophysical characteristics of mouse spermatogenic cell T-type currents more closely resemble those from heterologously expressed CaV3.1 channels, including their sensitivity to NA. As CaV3.1 null mice maintain their spermatogenic cell T-currents, it is likely that a novel CaV3.2 isoform is responsible for them. PMID:21898399

  13. Synthesis, structure and luminescent properties of rare earth coordination polymers constructed from paddle-wheel building blocks.

    PubMed

    Guo, Xiaodan; Zhu, Guangshan; Fang, Qianrong; Xue, Ming; Tian, Ge; Sun, Jinyu; Li, Xiaotian; Qiu, Shilun

    2005-05-30

    A series of three-dimensional (3D) novel coordination polymers M(bpdc)1.5(H2O) x 0.5DMF (M = Tb (1), Ho (2), Er (3), or Y (4)) have been synthesized by reaction of the rare earth ions (M3+) with 4,4'-biphenyldicarboxylic acid (H2bpdc) in a mixed solution of DMF and C2H5OH. They possess the same 3D architectures and crystallize in monoclinic space group C2/c. Two seven-coordinated metal centers and four dimonodentate bpdc groups construct a paddle-wheel building block. These building blocks connect with two carboxyl groups to lead to a one-dimensional inorganic chain, ---M-O-C-O-M---, along the [001] direction. The inorganic chains are linked with two biphenyl groups to form 25.15 A x 17.09 A rhombic channels along the c axis without interpenetration. These complexes exhibit strong fluorescence in the visible region, and complex 3 shows Er3+ characteristic emission in the range of 1450-1650 nm at room temperature. These complexes could be anticipated as potential fluorescent probes and an IR-emitter, respectively.

  14. Supramolecular self-assembly of 1D and 3D heterometallic coordination polymers with triruthenium building blocks.

    PubMed

    Chan, Sharon Lai-Fung; Gao, Song; Chui, Stephen Sin-Yin; Shek, Lam; Huang, Jie-Sheng; Che, Chi-Ming

    2012-09-03

    Ru(3)(TSA)(6) (1; H(2)TSA=2-thiosalicylic acid), which bears six peripheral carboxylate groups and was isolated in the form [NEt(4)](1.5)[Ru(3)(HTSA)(2)(TSA)(4)](OAc)(0.5)·3.5H(2)O, serves as a building block for assembly of heterometallic coordination polymers. Treatment of 1 with [Fe(acac)(3)] (acac=acetylacetonate) in EG/H(2)O (EG=ethylene glycol) afforded 1D Ru(3)-Fe coordination polymer 2 by means of the connection of the building block 1 through iron centers. Treatment of 1 with MnCl(2) in EG resulted in the formation of 1D Ru(3)-Mn(3) coordination polymer 3, which features self-assembled polynuclear linking units Mn(3)(OCH(2)CH(2)O)(3), each of which contains a planar Mn(3)O(3) ring. By treating 1 with Gd(NO(3))(3) and NaHCO(3) in EG, a 3D Ru(3)-Gd(6) coordination polymer 4 was obtained; this 3D coordination polymer features unprecedented Gd(6)(μ(3)-CO(3))(4) units. The magnetic properties of 1-4, along with DFT calculations on the electronic structure of 1, are also described.

  15. Molecular modeling of the elastomeric properties of repeating units and building blocks of resilin, a disordered elastic protein.

    PubMed

    Khandaker, Md Shahriar K; Dudek, Daniel M; Beers, Eric P; Dillard, David A; Bevan, David R

    2016-08-01

    The mechanisms responsible for the properties of disordered elastomeric proteins are not well known. To better understand the relationship between elastomeric behavior and amino acid sequence, we investigated resilin, a disordered rubber-like protein, found in specialized regions of the cuticle of insects. Resilin of Drosophila melanogaster contains Gly-rich repetitive motifs comprised of the amino acids, PSSSYGAPGGGNGGR, which confer elastic properties to resilin. The repetitive motifs of insect resilin can be divided into smaller partially conserved building blocks: PSS, SYGAP, GGGN and GGR. Using molecular dynamics (MD) simulations, we studied the relative roles of SYGAP, and its less common variants SYSAP and TYGAP, on the elastomeric properties of resilin. Results showed that SYGAP adopts a bent structure that is one-half to one-third the end-to-end length of the other motifs having an equal number of amino acids but containing SYSAP or TYGAP substituted for SYGAP. The bent structure of SYGAP forms due to conformational freedom of glycine, and hydrogen bonding within the motif apparently plays a role in maintaining this conformation. These structural features of SYGAP result in higher extensibility compared to other motifs, which may contribute to elastic properties at the macroscopic level. Overall, the results are consistent with a role for the SYGAP building block in the elastomeric properties of these disordered proteins. What we learned from simulating the repetitive motifs of resilin may be applicable to the biology and mechanics of other elastomeric biomaterials, and may provide us the deeper understanding of their unique properties.

  16. Furan-oxidation-triggered inducible DNA cross-linking: acyclic versus cyclic furan-containing building blocks--on the benefit of restoring the cyclic sugar backbone.

    PubMed

    Stevens, Kristof; Claeys, Diederica D; Catak, Saron; Figaroli, Sara; Hocek, Michal; Tromp, Jan M; Schürch, Stefan; Van Speybroeck, Veronique; Madder, Annemieke

    2011-06-14

    Oligodeoxynucleotides incorporating a reactive functionality can cause irreversible cross-linking to the target sequence and have been widely studied for their potential in inhibition of gene expression or development of diagnostic probes for gene analysis. Reactive oligonucleotides further show potential in a supramolecular context for the construction of nanometer-sized DNA-based objects. Inspired by the cytochrome P450 catalyzed transformation of furan into a reactive enal species, we recently introduced a furan-oxidation-based methodology for cross-linking of nucleic acids. Previous experiments using a simple acyclic building block equipped with a furan moiety for incorporation into oligodeoxynucleotides have shown that cross-linking occurs in a very fast and efficient way and that substantial amounts of stable, site-selectively cross-linked species can be isolated. Given the destabilization of duplexes observed upon introduction of the initially designed furan-modified building block into DNA duplexes, we explore here the potential benefits of two new building blocks featuring an extended aromatic system and a restored cyclic backbone. Thorough experimental analysis of cross-linking reactions in a series of contexts, combined with theoretical calculations, permit structural characterization of the formed species and allow assessment of the origin of the enhanced cross-link selectivity. Our experiments clearly show that the modular nature of the furan-modified building blocks used in the current cross-linking strategy allow for fine tuning of both yield and selectivity of the interstrand cross-linking reaction.

  17. Sunlight induced cycloaddition and host-guest property of self-assembled organometallic macrocycles based on a versatile building block.

    PubMed

    Wu, Tong; Weng, Lin-Hong; Jin, Guo-Xin

    2012-05-11

    Organometallic rectangle 1 which undergoes [2+2] cycloaddition upon irradiation with sunlight and organometallic prism 3 which displayed interesting host-guest property were self-assembled based on a versatile building block.

  18. Designed, Helical Protein Nanotubes with Variable Diameters from a Single Building Block.

    PubMed

    Brodin, Jeffrey D; Smith, Sarah J; Carr, Jessica R; Tezcan, F Akif

    2015-08-26

    Due to their structural and mechanical properties, 1D helical protein assemblies represent highly attractive design targets for biomolecular engineering and protein design. Here we present a designed, tetrameric protein building block, Zn8R4, which assembles via Zn coordination interactions into a series of crystalline, helical nanotubes whose widths can be controlled by solution conditions. X-ray crystallography and transmission electron microscopy (TEM) measurements indicate that all classes of protein nanotubes are constructed through the same 2D arrangement of Zn8R4 tetramers held together by Zn coordination. The mechanical properties of these nanotubes are correlated with their widths. All Zn8R4 nanotubes are found to be highly flexible despite possessing crystalline order, owing to their minimal interbuilding-block interactions mediated solely by metal coordination.

  19. A Customizable Quantum-Dot Cellular Automata Building Block for the Synthesis of Classical and Reversible Circuits.

    PubMed

    Moustafa, Ahmed; Younes, Ahmed; Hassan, Yasser F

    2015-01-01

    Quantum-dot cellular automata (QCA) are nanoscale digital logic constructs that use electrons in arrays of quantum dots to carry out binary operations. In this paper, a basic building block for QCA will be proposed. The proposed basic building block can be customized to implement classical gates, such as XOR and XNOR gates, and reversible gates, such as CNOT and Toffoli gates, with less cell count and/or better latency than other proposed designs.

  20. Automated electrochemical assembly of the protected potential TMG-chitotriomycin precursor based on rational optimization of the carbohydrate building block.

    PubMed

    Nokami, Toshiki; Isoda, Yuta; Sasaki, Norihiko; Takaiso, Aki; Hayase, Shuichi; Itoh, Toshiyuki; Hayashi, Ryutaro; Shimizu, Akihiro; Yoshida, Jun-ichi

    2015-03-20

    The anomeric arylthio group and the hydroxyl-protecting groups of thioglycosides were optimized to construct carbohydrate building blocks for automated electrochemical solution-phase synthesis of oligoglucosamines having 1,4-β-glycosidic linkages. The optimization study included density functional theory calculations, measurements of the oxidation potentials, and the trial synthesis of the chitotriose trisaccharide. The automated synthesis of the protected potential N,N,N-trimethyl-d-glucosaminylchitotriomycin precursor was accomplished by using the optimized building block.

  1. Utilization of the Building-Block Approach in Structural Mechanics Research

    NASA Technical Reports Server (NTRS)

    Rouse, Marshall; Jegley, Dawn C.; McGowan, David M.; Bush, Harold G.; Waters, W. Allen

    2005-01-01

    In the last 20 years NASA has worked in collaboration with industry to develop enabling technologies needed to make aircraft safer and more affordable, extend their lifetime, improve their reliability, better understand their behavior, and reduce their weight. To support these efforts, research programs starting with ideas and culminating in full-scale structural testing were conducted at the NASA Langley Research Center. Each program contained development efforts that (a) started with selecting the material system and manufacturing approach; (b) moved on to experimentation and analysis of small samples to characterize the system and quantify behavior in the presence of defects like damage and imperfections; (c) progressed on to examining larger structures to examine buckling behavior, combined loadings, and built-up structures; and (d) finally moved to complicated subcomponents and full-scale components. Each step along the way was supported by detailed analysis, including tool development, to prove that the behavior of these structures was well-understood and predictable. This approach for developing technology became known as the "building-block" approach. In the Advanced Composites Technology Program and the High Speed Research Program the building-block approach was used to develop a true understanding of the response of the structures involved through experimentation and analysis. The philosophy that if the structural response couldn't be accurately predicted, it wasn't really understood, was critical to the progression of these programs. To this end, analytical techniques including closed-form and finite elements were employed and experimentation used to verify assumptions at each step along the way. This paper presents a discussion of the utilization of the building-block approach described previously in structural mechanics research and development programs at NASA Langley Research Center. Specific examples that illustrate the use of this approach are

  2. Building biologically active nucleic acid nanocomplexes.

    PubMed

    Smith, C I Edvard; Lundin, Karin E; Simonson, Oscar E; Moreno, Pedro M D; Svahn, Mathias G; Wenska, Malgorzata; Strömberg, Roger

    2008-01-01

    The Bioplex technology allows the hybridization of functional entities to various forms of nucleic acids by the use of synthetic nucleic acid analogs. Such supramolecular assemblies can be made in a predetermined fashion and can confer new properties. The Zorro technology is based on a novel construct generated to simultaneously bind to both DNA strands. Such compounds may have gene silencing activity.

  3. Search for water and life's building blocks in the Universe: An Introduction

    NASA Astrophysics Data System (ADS)

    Kwok, Sun

    Water and organics are commonly believed to be the essential ingredients for life on Earth. The development of infrared and submillimeter observational techniques has resulted in the detection of water in circumstellar envelopes, interstellar clouds, comets, asteroids, planetary satellites and the Sun. Complex organics have also been found in stellar ejecta, diffuse and molecular clouds, meteorites, interplanetary dust particles, comets and planetary satellites. In this Focus Meeting, we will discuss the origin, distribution, and detection of water and other life's building blocks both inside and outside of the Solar System. The possibility of extraterrestrial organics and water on the origin of life on Earth will also be discussed.

  4. Evaluating the family nurse partnership in England: the Building Blocks trial.

    PubMed

    Sanders, Julia; Owen-Jones, Eleri; Robling, Mike

    2011-01-01

    The Family Nurse Partnership (FNP) Programme is a structured intensive home visiting programme delivered by trained family nurses to nulliparous teenagers throughout pregnancy and until their child is two years old. Currently FNP is provided in over 60 primary healthcare sites in England with a planned capacity increase to 13,000 concurrent clients by 2015. Researchers from the South East Wales Trials Unit at Cardiff University are testing the effectiveness of FNP in England in the Building Blocks study--a randomised controlled trial funded by the Department of Health (DH). The trial team includes collaborators from the Universities of York, Bristol and Glamorgan.

  5. Metal-oxide based nanoobjects: reactivity, building blocks for polymeric structures and structural variety

    NASA Astrophysics Data System (ADS)

    Müller, Achim; Roy, Soumyajit

    2002-12-01

    From the unique 'library' of molybdenum-oxide based building blocks/fragments under reducing conditions in aqueous solution a huge variety of nanoobjects, allowing specific reactions at well-defined positions, can be generated. This enables us to perform a new type of nanochemistry. Examples include the well-known molecular big-wheel of the type {Mo176} and big-ball of the type {Mo132} including their derivatives which are considered here. In addition, the by far largest structurally well-characterised cluster having 368 molybdenum atoms with the shape of a lemon is outlined and discussed. The bibliography includes 71 references.

  6. Clinical postconference pedagogy: exploring evidence-based practice with millennial-inspired "Building Blocks".

    PubMed

    Schams, Kristin A; Kuennen, Jackie K

    2012-01-01

    This article reports an innovative teaching strategy consisting of learning units whereby students come to postconference sessions prepared to share evidence-based practice (EBP) information associated with upcoming laboratory concepts, discover relationships among laboratory concepts and current nursing practice, and associate personal clinical experiences with the practice environment. This strategy, named "Building Blocks," represents one method to transform nursing education into a more active process, and also has the potential to prepare graduates who can function in a dynamic health care environment incorporating EBP.

  7. Impact: a low cost, reconfigurable, digital beamforming common module building block for next generation phased arrays

    NASA Astrophysics Data System (ADS)

    Paulsen, Lee; Hoffmann, Ted; Fulton, Caleb; Yeary, Mark; Saunders, Austin; Thompson, Dan; Chen, Bill; Guo, Alex; Murmann, Boris

    2015-05-01

    Phased array systems offer numerous advantages to the modern warfighter in multiple application spaces, including Radar, Electronic Warfare, Signals Intelligence, and Communications. However, a lack of commonality in the underlying technology base for DoD Phased Arrays has led to static systems with long development cycles, slow technology refreshes in response to emerging threats, and expensive, application-specific sub-components. The IMPACT module (Integrated Multi-use Phased Array Common Tile) is a multi-channel, reconfigurable, cost-effective beamformer that provides a common building block for multiple, disparate array applications.

  8. Dialkoxybithiazole: a new building block for head-to-head polymer semiconductors.

    PubMed

    Guo, Xugang; Quinn, Jordan; Chen, Zhihua; Usta, Hakan; Zheng, Yan; Xia, Yu; Hennek, Jonathan W; Ortiz, Rocío Ponce; Marks, Tobin J; Facchetti, Antonio

    2013-02-06

    Polymer semiconductors have received great attention for organic electronics due to the low fabrication cost offered by solution-based printing techniques. To enable the desired solubility/processability and carrier mobility, polymers are functionalized with hydrocarbon chains by strategically manipulating the alkylation patterns. Note that head-to-head (HH) linkages have traditionally been avoided because the induced backbone torsion leads to poor π-π overlap and amorphous film microstructures, and hence to low carrier mobilities. We report here the synthesis of a new building block for HH linkages, 4,4'-dialkoxy-5,5'-bithiazole (BTzOR), and its incorporation into polymers for high performance organic thin-film transistors. The small oxygen van der Waals radius and intramolecular S(thiazolyl)···O(alkoxy) attraction promote HH macromolecular architectures with extensive π-conjugation, low bandgaps (1.40-1.63 eV), and high crystallinity. In comparison to previously reported 3,3'-dialkoxy-2,2'-bithiophene (BTOR), BTzOR is a promising building block in view of thiazole geometric and electronic properties: (a) replacing (thiophene)C-H with (thiazole)N reduces steric encumbrance in -BTzOR-Ar- dyads by eliminating repulsive C-H···H-C interactions with neighboring arene units, thereby enhancing π-π overlap and film crystallinity; and (b) thiazole electron-deficiency compensates alkoxy electron-donating characteristics, thereby lowering the BTzOR polymer HOMO versus that of the BTOR analogues. Thus, the new BTzOR polymers show substantial hole mobilities (0.06-0.25 cm(2)/(V s)) in organic thin-film transistors, as well as enhanced I(on):I(off) ratios and greater ambient stability than the BTOR analogues. These geometric and electronic properties make BTzOR a promising building block for new classes of polymer semiconductors, and the synthetic route to BTzOR reported here should be adaptable to many other bithiazole-based building blocks.

  9. Molecular building blocks and their architecture in biologically/environmentally compatible soft matter chemical machinery.

    PubMed

    Toyota, Taro; Banno, Taisuke; Nitta, Sachiko; Takinoue, Masahiro; Nomoto, Tomonori; Natsume, Yuno; Matsumura, Shuichi; Fujinami, Masanori

    2014-01-01

    This review briefly summarizes recent developments in the construction of biologically/environmentally compatible chemical machinery composed of soft matter. Since environmental and living systems are open systems, chemical machinery must continuously fulfill its functions not only through the influx and generation of molecules but also via the degradation and dissipation of molecules. If the degradation or dissipation of soft matter molecular building blocks and biomaterial molecules/polymers can be achieved, soft matter particles composed of them can be used to realize chemical machinery such as selfpropelled droplets, drug delivery carriers, tissue regeneration scaffolds, protocell models, cell-/tissuemarkers, and molecular computing systems.

  10. Enzymatic Ligation Creates Discrete Multi-Nanoparticle Building Blocks for Self-Assembly

    SciTech Connect

    Claridge, Shelley A.; Mastroianni, Alexander J.; Au, Yeung B.; Liang, Huiyang W.; Micheel, Christine M.; Frechet, Jean M.J.; Alivisatos, A. Paul

    2008-05-27

    Enzymatic ligation of discrete nanoparticle?DNA conjugates creates nanoparticle dimer and trimer structures in which the nanoparticles are linked by single-stranded DNA, rather than double-stranded DNA as in previous experiments. Ligation is verified by agarose gel and small-angle X-ray scattering. This capability is utilized in two ways: first to create a new class of multiparticle building blocks for nanoscale self-assembly; second to develop a system which can amplify a population of discrete nanoparticle assemblies.

  11. 324 and 325 Building Hot Cell Cleanout Program: Air lock cover block refurbishment

    SciTech Connect

    Katayama, Y.B.; Holton, L.K. Jr.; Gale, R.M.

    1989-05-01

    The high-density concrete cover blocks shielding the pipe trench in the hot-cell air lock of the 324 Building Radiochemical Engineering Cells had accumulated fixed radioactivity ranging from 1100 to 22, 000 mrad/hr. A corresponding increase in the radiation exposure to personnel entering the air lock, together with ALARA concerns, led to the removal of the contaminated concrete surface with a hydraulic spaller and the emplacement of a stainless steel covering over a layer of grout. The resultant saving in radiation exposure is estimated to be 7200 mrad for personnel completing burial box runs for the 324 and 325 Building Hot Cell Cleanout Program. Radiation exposure to all staff members entering the air lock is now at least 50% lower. 3 refs., 22 figs., 1 tab.

  12. Social motivation and conflict resolution tactics as potential building blocks of sociality in cichlid fishes.

    PubMed

    Balshine, Sigal; Wong, Marian Y L; Reddon, Adam R

    2017-01-03

    Even closely related and ecologically similar cichlid species of Lake Tanganyika exhibit an impressive diversity of social systems, and therefore these fishes offer an excellent opportunity to examine the evolution of social behaviour. Sophisticated social relationships are thought to have evolved via a building block design where more fundamental social behaviours and cognitive processes have been combined, incrementally modified, and elaborated over time. Here, we studied two of these putative social building blocks in two closely related species of cichlids: Neolamprologus pulcher, a group-living species, and Telmatochromis temporalis, a non-grouping species. Otherwise well matched in ecology, this pair of species provide an excellent comparison point to understand how behavioural processes may have been modified in relation to the evolution of sociality. Using social assays in both the laboratory and in the field, we explored each species' motivation to interact with conspecifics, and each species' conflict resolution tactics. We found that individuals of the group living species, N. pulcher, displayed higher social motivation and were more likely to produce submission displays than were individuals of the non-grouping species, T. temporalis. We argue that the motivation to interact with conspecifics is a necessary prerequisite for the emergence of group living, and that the use of submission reduces the costs of conflict and facilitates the maintenance of close social proximity. These results suggest that social motivation and conflict resolution tactics are associated with social complexity, and that these behavioural traits may be functionally significant in the evolution and maintenance of sociality.

  13. Accelerated wound healing by injectable microporous gel scaffolds assembled from annealed building blocks

    PubMed Central

    Griffin, Donald R.; Weaver, Westbrook M.; Scumpia, Philip; Di Carlo, Dino; Segura, Tatiana

    2015-01-01

    Summary Injectable hydrogels can provide a scaffold for in situ tissue regrowth and regeneration, however these injected materials require gel degradation prior to tissue reformation limiting their ability to provide physical support. We have created a new class of injectable biomaterial that circumvents this challenge by providing an interconnected microporous network for simultaneous tissue reformation and material degradation. We assemble monodisperse micro-gel building blocks into an interconnected microporous annealed particle (MAP) scaffold. Through microfluidic formation, we tailor the chemical and physical properties of the building blocks, providing downstream control of the physical and chemical properties of the assembled MAP scaffold. In vitro, cells incorporated during MAP scaffold formation proliferated and formed extensive 3D networks within 48 hours. In vivo, the injectable MAP scaffold facilitated cell migration resulting in rapid cutaneous tissue regeneration and tissue structure formation within 5 days. The combination of microporosity and injectability achieved with MAP scaffolds will enable novel routes to tissue regeneration in vivo and tissue creation de novo. PMID:26030305

  14. Self-assembling SAS-6 multimer is a core centriole building block.

    PubMed

    Gopalakrishnan, Jayachandran; Guichard, Paul; Smith, Andrew H; Schwarz, Heinz; Agard, David A; Marco, Sergio; Avidor-Reiss, Tomer

    2010-03-19

    Centrioles are conserved microtubule-based organelles with 9-fold symmetry that are essential for cilia and mitotic spindle formation. A conserved structure at the onset of centriole assembly is a "cartwheel" with 9-fold radial symmetry and a central tubule in its core. It remains unclear how the cartwheel is formed. The conserved centriole protein, SAS-6, is a cartwheel component that functions early in centriole formation. Here, combining biochemistry and electron microscopy, we characterize SAS-6 and show that it self-assembles into stable tetramers, which serve as building blocks for the central tubule. These results suggest that SAS-6 self-assembly may be an initial step in the formation of the cartwheel that provides the 9-fold symmetry. Electron microscopy of centrosomes identified 25-nm central tubules with repeating subunits and show that SAS-6 concentrates at the core of the cartwheel. Recombinant and native SAS-6 self-oligomerizes into tetramers with approximately 6-nm subunits, and these tetramers are components of the centrosome, suggesting that tetramers are the building blocks of the central tubule. This is further supported by the observation that elevated levels of SAS-6 in Drosophila cells resulted in higher order structures resembling central tubule morphology. Finally, in the presence of embryonic extract, SAS-6 tetramers assembled into high density complexes, providing a starting point for the eventual in vitro reconstruction of centrioles.

  15. Assessing the Potential of Folded Globular Polyproteins As Hydrogel Building Blocks

    PubMed Central

    2016-01-01

    The native states of proteins generally have stable well-defined folded structures endowing these biomolecules with specific functionality and molecular recognition abilities. Here we explore the potential of using folded globular polyproteins as building blocks for hydrogels. Photochemically cross-linked hydrogels were produced from polyproteins containing either five domains of I27 ((I27)5), protein L ((pL)5), or a 1:1 blend of these proteins. SAXS analysis showed that (I27)5 exists as a single rod-like structure, while (pL)5 shows signatures of self-aggregation in solution. SANS measurements showed that both polyprotein hydrogels have a similar nanoscopic structure, with protein L hydrogels being formed from smaller and more compact clusters. The polyprotein hydrogels showed small energy dissipation in a load/unload cycle, which significantly increased when the hydrogels were formed in the unfolded state. This study demonstrates the use of folded proteins as building blocks in hydrogels, and highlights the potential versatility that can be offered in tuning the mechanical, structural, and functional properties of polyproteins. PMID:28006103

  16. Mesoscopic packing of disk-like building blocks in calcium silicate hydrate

    PubMed Central

    Yu, Zechuan; Zhou, Ao; Lau, Denvid

    2016-01-01

    At 100-nanometer length scale, the mesoscopic structure of calcium silicate hydrate (C-S-H) plays a critical role in determining the macroscopic material properties, such as porosity. In order to explore the mesoscopic structure of C-S-H, we employ two effective techniques, nanoindentation test and molecular dynamics simulation. Grid nanoindentation tests find different porosity of C-S-H in cement paste specimens prepared at varied water-to-cement (w/c) ratios. The w/c-ratio-induced porosity difference can be ascribed to the aspect ratio (diameter-to-thickness ratio) of disk-like C-S-H building blocks. The molecular dynamics simulation, with a mesoscopic C-S-H model, reveals 3 typical packing patterns and relates the packing density to the aspect ratio. Illustrated with disk-like C-S-H building blocks, this study provides a description of C-S-H structures in complement to spherical-particle C-S-H models at the sub-micron scale. PMID:27845376

  17. Multifunctional Nanoparticles Self-Assembled from Small Organic Building Blocks for Biomedicine.

    PubMed

    Xing, Pengyao; Zhao, Yanli

    2016-09-01

    Supramolecular self-assembly shows significant potential to construct responsive materials. By tailoring the structural parameters of organic building blocks, nanosystems can be fabricated, whose performance in catalysis, energy storage and conversion, and biomedicine has been explored. Since small organic building blocks are structurally simple, easily modified, and reproducible, they are frequently employed in supramolecular self-assembly and materials science. The dynamic and adaptive nature of self-assembled nanoarchitectures affords an enhanced sensitivity to the changes in environmental conditions, favoring their applications in controllable drug release and bioimaging. Here, recent significant research advancements of small-organic-molecule self-assembled nanoarchitectures toward biomedical applications are highlighted. Functionalized assemblies, mainly including vesicles, nanoparticles, and micelles are categorized according to their topological morphologies and functions. These nanoarchitectures with different topologies possess distinguishing advantages in biological applications, well incarnating the structure-property relationship. By presenting some important discoveries, three domains of these nanoarchitectures in biomedical research are covered, including biosensors, bioimaging, and controlled release/therapy. The strategies regarding how to design and characterize organic assemblies to exhibit biomedical applications are also discussed. Up-to-date research developments in the field are provided and research challenges to be overcome in future studies are revealed.

  18. Engineering cell factories for producing building block chemicals for bio-polymer synthesis.

    PubMed

    Tsuge, Yota; Kawaguchi, Hideo; Sasaki, Kengo; Kondo, Akihiko

    2016-01-21

    Synthetic polymers are widely used in daily life. Due to increasing environmental concerns related to global warming and the depletion of oil reserves, the development of microbial-based fermentation processes for the production of polymer building block chemicals from renewable resources is desirable to replace current petroleum-based methods. To this end, strains that efficiently produce the target chemicals at high yields and productivity are needed. Recent advances in metabolic engineering have enabled the biosynthesis of polymer compounds at high yield and productivities by governing the carbon flux towards the target chemicals. Using these methods, microbial strains have been engineered to produce monomer chemicals for replacing traditional petroleum-derived aliphatic polymers. These developments also raise the possibility of microbial production of aromatic chemicals for synthesizing high-performance polymers with desirable properties, such as ultraviolet absorbance, high thermal resistance, and mechanical strength. In the present review, we summarize recent progress in metabolic engineering approaches to optimize microbial strains for producing building blocks to synthesize aliphatic and high-performance aromatic polymers.

  19. U.S. national categorical mapping of building heights by block group from Shuttle Radar Topography Mission data

    USGS Publications Warehouse

    Falcone, James

    2016-01-01

    This dataset is a categorical mapping of estimated mean building heights, by Census block group, in shapefile format for the conterminous United States. The data were derived from the NASA Shuttle Radar Topography Mission, which collected “first return” (top of canopy and buildings) radar data at 30-m resolution in February, 2000 aboard the Space Shuttle Endeavor. These data were processed here to estimate building heights nationally, and then aggregated to block group boundaries. The block groups were then categorized into six classes, ranging from “Low” to “Very High”, based on the mean and standard deviation breakpoints of the data. The data were evaluated in several ways, to include comparing them to a reference dataset of 85,000 buildings for the city of San Francisco for accuracy assessment and to provide contextual definitions for the categories.

  20. Culture's building blocks: investigating cultural evolution in a LEGO construction task.

    PubMed

    McGraw, John J; Wallot, Sebastian; Mitkidis, Panagiotis; Roepstorff, Andreas

    2014-01-01

    ONE OF THE MOST ESSENTIAL BUT THEORETICALLY VEXING ISSUES REGARDING THE NOTION OF CULTURE IS THAT OF CULTURAL EVOLUTION AND TRANSMISSION: how a group's accumulated solutions to invariant challenges develop and persevere over time. But at the moment, the notion of applying evolutionary theory to culture remains little more than a suggestive trope. Whereas the modern synthesis of evolutionary theory has provided an encompassing scientific framework for the selection and transmission of biological adaptations, a convincing theory of cultural evolution has yet to emerge. One of the greatest challenges for theorists is identifying the appropriate time scales and units of analysis in order to reduce the intractably large and complex phenomenon of "culture" into its component "building blocks." In this paper, we present a model for scientifically investigating cultural processes by analyzing the ways people develop conventions in a series of LEGO construction tasks. The data revealed a surprising pattern in the selection of building bricks as well as features of car design across consecutive building sessions. Our findings support a novel methodology for studying the development and transmission of culture through the microcosm of interactive LEGO design and assembly.

  1. Culture’s building blocks: investigating cultural evolution in a LEGO construction task

    PubMed Central

    McGraw, John J.; Wallot, Sebastian; Mitkidis, Panagiotis; Roepstorff, Andreas

    2014-01-01

    One of the most essential but theoretically vexing issues regarding the notion of culture is that of cultural evolution and transmission: how a group’s accumulated solutions to invariant challenges develop and persevere over time. But at the moment, the notion of applying evolutionary theory to culture remains little more than a suggestive trope. Whereas the modern synthesis of evolutionary theory has provided an encompassing scientific framework for the selection and transmission of biological adaptations, a convincing theory of cultural evolution has yet to emerge. One of the greatest challenges for theorists is identifying the appropriate time scales and units of analysis in order to reduce the intractably large and complex phenomenon of “culture” into its component “building blocks.” In this paper, we present a model for scientifically investigating cultural processes by analyzing the ways people develop conventions in a series of LEGO construction tasks. The data revealed a surprising pattern in the selection of building bricks as well as features of car design across consecutive building sessions. Our findings support a novel methodology for studying the development and transmission of culture through the microcosm of interactive LEGO design and assembly. PMID:25309482

  2. RNA and RNP as Building Blocks for Nanotechnology and Synthetic Biology.

    PubMed

    Ohno, Hirohisa; Saito, Hirohide

    2016-01-01

    Recent technologies that aimed to elucidate cellular function have revealed essential roles for RNA molecules in living systems. Our knowledge concerning functional and structural information of naturally occurring RNA and RNA-protein (RNP) complexes is increasing rapidly. RNA and RNP interaction motifs are structural units that function as building blocks to constitute variety of complex structures. RNA-central synthetic biology and nanotechnology are constructive approaches that employ the accumulated information and build synthetic RNA (RNP)-based circuits and nanostructures. Here, we describe how to design and construct synthetic RNA (RNP)-based devices and structures at the nanometer-scale for biological and future therapeutic applications. RNA/RNP nanostructures can also be utilized as the molecular scaffold to control the localization or interactions of target molecule(s). Moreover, RNA motifs recognized by RNA-binding proteins can be applied to make protein-responsive translational "switches" that can turn gene expression "on" or "off" depending on the intracellular environment. This "synthetic RNA and RNP world" will expand tools for nanotechnology and synthetic biology. In addition, these reconstructive approaches would lead to a greater understanding of building principle in naturally occurring RNA/RNP molecules and systems.

  3. 2-Alkynylbenzaldoxime: a versatile building block for the generation of N-heterocycles.

    PubMed

    He, Linman; Nie, Hongming; Qiu, Guanyinsheng; Gao, Yueqiu; Wu, Jie

    2014-12-07

    2-Alkynylbenzaldoxime as a versatile building block has been applied widely for the construction of N-heterocycles in organic synthesis. Since it could be easily transferred to isoquinoline N-oxide via intramolecular 6-endo cyclization in the presence of metal catalysts or electrophiles, the subsequent [3 + 2] cycloaddition/nucleophilic addition and rearrangement could be expected. On the other hand, a Beckmann rearrangement could occur first since an oxime moiety is present in the molecule, which would then undergo an intramolecular cyclization to furnish nitrogen-containing heterocycles. This review reports the recent advancement in the generation of N-heterocycles starting from 2-alkynylbenzaldoximes via tandem reactions based on different reaction types.

  4. Access to a new class of synthetic building blocks via trifluoromethoxylation of pyridines and pyrimidines†

    PubMed Central

    Feng, Pengju; Lee, Katarzyna N.; Lee, Johnny W.; Zhan, Chengbo

    2016-01-01

    Since the first synthesis of trifluoromethyl ethers in 1935, the trifluoromethoxy (OCF3) group has made a remarkable impact in medicinal, agrochemical, and materials science research. However, our inability to facilely incorporate the OCF3 group into molecules, especially heteroaromatics, has limited its potential across a broad spectrum of technological applications. Herein, we report a scalable and operationally simple protocol for regioselective trifluoromethoxylation of a wide range of functionalized pyridines and pyrimidines under mild reaction conditions. The trifluoromethoxylated products are useful scaffolds that can be further elaborated by amidation and palladium-catalysed cross coupling reactions. Mechanistic studies suggest that a radical O-trifluoromethylation followed by the OCF3-migration reaction pathway is operable. Given the unique properties of the OCF3 group and the ubiquity of pyridine and pyrimidine in biologically active molecules and functional materials, trifluoromethoxylated pyridines and pyrimidines could serve as valuable building blocks for the discovery and development of new drugs, agrochemicals, and materials. PMID:27857834

  5. β-Diketo Building Blocks for MCRs-Based Syntheses of Heterocycles

    NASA Astrophysics Data System (ADS)

    Del Duque, Maria Mar Sanchez; Allais, Christophe; Isambert, Nicolas; Constantieux, Thierry; Rodriguez, Jean

    In the context of sustainable chemistry, because of economic and ecological increasing pressure, domino multicomponent reactions (MCRs) constitute a central academic and industrial investigation domain in diversity-oriented synthesis of functionalized heterocycles. Although isocyanide-based MCRs generally predominate nowadays, the use of 1,3-dicarbonyls as substrates, proposed as early as 1882 by Hantzsch, proved to be highly efficient, but have been relatively unexplored until recently. In the last few years, such transformations received a growing attention as new useful methodologies valuable for the selective direct access to highly functionalized small organic molecules of primary synthetic and biological value. This review focuses on the more significant recent developments on the use of β-diketo building blocks for MCRs published in the last 5 years.

  6. Aldo-X Bifunctional Building Blocks for the Synthesis of Heterocycles.

    PubMed

    Ravichandiran, Palanisamy; Lai, Bingbing; Gu, Yanlong

    2017-02-01

    Compounds containing oxygen, nitrogen, or sulfur atoms inside the rings are attracting much attention and interest due to their biological importance. In recent years, several methods for the synthesis of such molecules have been reported by using aldo-X bifunctional building blocks (AXB3 s) as substrates; these are a wide class of organic molecules that contain at least two reactive sites, among them, one aldehyde, acetal, or semiacetal group was involved. Because of the multiple reactivities, AXB3 s are widely used in the one-pot synthesis of biologically important heterocycles. This review summarizes the synthesis of important heterocycles by using AXB3 s as pivotal components in establishing multicomponent reactions, tandem reactions, and so forth. In many cases, the established reaction systems with AXB3 s were characterized by some green properties, such as easy access to the substrate, mild and environmentally benign conditions, and wide scope of the substrate.

  7. Amphiphilic polysaccharide nanoballs: a new building block for nanogel biomedical engineering and artificial chaperones.

    PubMed

    Takahashi, Haruko; Sawada, Shin-Ichi; Akiyoshi, Kazunari

    2011-01-25

    Enzymatically synthesized glycogen (ESG), a highly branched (1→4)(1→6)-linked α-glucan, is a new monodisperse spherical hyperbranched nanoparticle (molecular weight, 10(6)-10(7); diameter, 20-30 nm), polysaccharide nanoball. Amphiphilic ESG nanoballs were synthesized by introducing a cholesterol group to enzymatically synthesized glycogen (CHESG). CHESG assembled into a structure containing a few molecules to form cluster nanogels (approximately 35 nm in diameter) in water. The cluster nanogels were dissociated by the addition of cyclodextrin (CD) to form a supramolecular CHESG-CD nanocomplex due to complexation with the cholesterol group and CD. The CHESG nanogel showed high capacity for complexation with proteins, and the CHESG-CD nanocomplex showed high chaperone-like activity for thermal stabilization of enzymes. CHESG has great potential to become a new building block for nanogel biomedical engineering and to act as an artificial chaperone for protein engineering.

  8. Low-voltage FGMOS squarer/divider-based analog building blocks

    NASA Astrophysics Data System (ADS)

    Srivastava, Richa; Gupta, Maneesha; Singh, Urvashi

    2015-04-01

    This paper presents a new low-voltage floating gate MOS (FGMOS)-based current-mode squarer/divider circuit. The low-voltage operation is obtained by replacing the PMOS transistor used to bias the conventional circuit with two-input FGMOS. The proposed circuit offers advantage of two-quadrant operation, low supply voltage (0.85 V) requirement, low circuit complexity and low noise as compared to the conventional one. The proposed circuit is then used as basic building block to develop full Gaussian function generator and RMS-to-DC converter. The simulations are performed in TSMC 0.18 µm CMOS, BSIM3 and Level 49 technology by using Spectre simulator of Cadence.

  9. Digital NMR profiles as building blocks: assembling ¹H fingerprints of steviol glycosides.

    PubMed

    Napolitano, José G; Simmler, Charlotte; McAlpine, James B; Lankin, David C; Chen, Shao-Nong; Pauli, Guido F

    2015-04-24

    This report describes a fragment-based approach to the examination of congeneric organic compounds by NMR spectroscopy. The method combines the classic interpretation of 1D- and 2D-NMR data sets with contemporary computer-assisted NMR analysis. Characteristic NMR profiles of key structural motifs were generated by (1)H iterative full spin analysis and then joined together as building blocks to recreate the (1)H NMR spectra of increasingly complex molecules. To illustrate the methodology described, a comprehensive analysis of steviol (1), seven steviol glycosides (2-8) and two structurally related isosteviol compounds (9, 10) was carried out. The study also assessed the potential impact of this method on relevant aspects of natural product research including structural verification, chemical dereplication, and mixture analysis.

  10. Extended structure design with simple molybdenum oxide building blocks and urea as a directing agent.

    PubMed

    Veen, Sandra J; Roy, Soumyajit; Filinchuk, Yaroslav; Chernyshov, Dmitry; Petukhov, Andrei V; Versluijs-Helder, Marjan; Broersma, Alfred; Soulimani, Fouad; Visser, Tom; Kegel, Willem K

    2008-08-04

    We report here a simple one-pot directed synthesis of an oxomolybdate urea composite in which elementary molybdenum oxide building blocks are linked together with the aid of urea. This type of directed material design resulted in large rod-like crystals of an inorganic-organic hybrid extended structure of {MoO 3(NH 2-CO-NH 2)} infinity consisting of right- and left-handed helical units. In the crystal structure urea acts both as a glue that links the inorganic molybdenum units into a helix and as a supramolecular linker for the stabilization of the crystal structure as a whole. This type of molecular topology resulted in an unexpectedly high thermal stability.

  11. Remote Stabilization of Copper Paddlewheel Based Molecular Building Blocks in Metal-Organic Frameworks

    SciTech Connect

    Gao, Wen-Yang; Cai, Rong; Pham, Tony; Forrest, Katherine A.; Hogan, Adam; Nugent, Patrick; Williams, Kia; Wojtas, Lukasz; Luebke, Ryan; Weseliinski, Lukasz J.; Zaworotko, Michael J.; Space, Brian; Chen, Yu-Sheng; Eddaoudi, Mohamed; Shi, Xiaodong; Ma, Shengqian

    2015-08-21

    Copper paddlewheel based molecular building blocks (MBBs) are ubiquitous and have been widely employed for the construction of highly porous metal–organic frameworks (MOFs). However, most copper paddlewheel based MOFs fail to retain their structural integrity in the presence of water. This instability is directly correlated to the plausible displacement of coordinating carboxylates in the copper paddlewheel MBB, [Cu₂(O₂C-)₄], by the strongly coordinating water molecules. In this comprehensive study, we illustrate the chemical stability control in the rht-MOF platform via strengthening the coordinating bonds within the triangular inorganic MBB, [Cu₃O(N4–x(CH)xC-)₃] (x = 0, 1, or 2). Remotely, the chemical stabilization propagated into the paddlewheel MBB to afford isoreticular rht-MOFs with remarkably enhanced water/chemical stabilities compared to the prototypal rht-MOF-1.

  12. Three distinct ribosome assemblies modulated by translation are the building blocks of polysomes

    PubMed Central

    Lunelli, Lorenzo; Passerini, Andrea; Bianchini, Paolo; Gilbert, Robert J.; Bernabò, Paola; Tebaldi, Toma; Diaspro, Alberto; Pederzolli, Cecilia

    2015-01-01

    Translation is increasingly recognized as a central control layer of gene expression in eukaryotic cells. The overall organization of mRNA and ribosomes within polysomes, as well as the possible role of this organization in translation are poorly understood. Here we show that polysomes are primarily formed by three distinct classes of ribosome assemblies. We observe that these assemblies can be connected by naked RNA regions of the transcript. We show that the relative proportions of the three classes of ribosome assemblies reflect, and probably dictate, the level of translational activity. These results reveal the existence of recurrent supra-ribosomal building blocks forming polysomes and suggest the presence of unexplored translational controls embedded in the polysome structure. PMID:25713412

  13. Biophysics and Thermodynamics: The Scientific Building Blocks of Bio-inspired Drug Delivery Nano Systems.

    PubMed

    Demetzos, Costas

    2015-06-01

    Biophysics and thermodynamics are considered as the scientific milestones for investigating the properties of materials. The relationship between the changes of temperature with the biophysical variables of biomaterials is important in the process of the development of drug delivery systems. Biophysics is a challenge sector of physics and should be used complementary with the biochemistry in order to discover new and promising technological platforms (i.e., drug delivery systems) and to disclose the 'silence functionality' of bio-inspired biological and artificial membranes. Thermal analysis and biophysical approaches in pharmaceuticals present reliable and versatile tools for their characterization and for the successful development of pharmaceutical products. The metastable phases of self-assembled nanostructures such as liposomes should be taken into consideration because they represent the thermal events can affect the functionality of advanced drug delivery nano systems. In conclusion, biophysics and thermodynamics are characterized as the building blocks for design and development of bio-inspired drug delivery systems.

  14. Repeat protein engineering: creating functional nanostructures/biomaterials from modular building blocks.

    PubMed

    Main, Ewan R G; Phillips, Jonathan J; Millership, Charlotte

    2013-10-01

    There is enormous interest in molecular self-assembly and the development of biological systems to form smart nanostructures for biotechnology (so-called 'bottom-up fabrications'). Repeat proteins are ideal choices for development of such systems as they: (i) possess a relatively simple relationship between sequence, structure and function; (ii) are modular and non-globular in structure; (iii) act as diverse scaffolds for the mediation of a diverse range of protein-protein interactions; and (iv) have been extensively studied and successfully engineered and designed. In the present review, we summarize recent advances in the use of engineered repeat proteins in the self-assembly of novel materials, nanostructures and biosensors. In particular, we show that repeat proteins are excellent monomeric programmable building blocks that can be triggered to associate into a range of morphologies and can readily be engineered as stimuli-responsive biofunctional materials.

  15. The Local Dwarf GALAXIES:BUILDING Blocks of Massive Ones? I.THE Fornax Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Nykytyuk, T. V.

    A chemical evolution of the Local Group dwarf galaxy Fornax is considered in the framework of the merger scenario. We suppose a galactic stellar halo to be formed as separate fragments which then merge; thus, we can calculate the set of such the fragments to reproduce the observed metallicity distribution function of a galaxy. Accordingly, if dwarf galaxies were such the systems, which, once merged, have formed massive galaxies, we need to obtain only one fragment to reproduce the observed metallicity distribution function of a dwarf galaxy. To test this assumption, the stellar metallicity distribution functions of Fornax was calculated in the framework of the merger scenario. The more than one fragment was obtained for galaxy under consideration; thus, it is unlikely the systems similar to Fornax to be building blocks of massive galaxies.

  16. Learning and optimization with cascaded VLSI neural network building-block chips

    NASA Technical Reports Server (NTRS)

    Duong, T.; Eberhardt, S. P.; Tran, M.; Daud, T.; Thakoor, A. P.

    1992-01-01

    To demonstrate the versatility of the building-block approach, two neural network applications were implemented on cascaded analog VLSI chips. Weights were implemented using 7-b multiplying digital-to-analog converter (MDAC) synapse circuits, with 31 x 32 and 32 x 32 synapses per chip. A novel learning algorithm compatible with analog VLSI was applied to the two-input parity problem. The algorithm combines dynamically evolving architecture with limited gradient-descent backpropagation for efficient and versatile supervised learning. To implement the learning algorithm in hardware, synapse circuits were paralleled for additional quantization levels. The hardware-in-the-loop learning system allocated 2-5 hidden neurons for parity problems. Also, a 7 x 7 assignment problem was mapped onto a cascaded 64-neuron fully connected feedback network. In 100 randomly selected problems, the network found optimal or good solutions in most cases, with settling times in the range of 7-100 microseconds.

  17. Digital NMR Profiles as Building Blocks: Assembling 1H Fingerprints of Steviol Glycosides

    PubMed Central

    Napolitano, José G.; Simmler, Charlotte; McAlpine, James B.; Lankin, David C.; Chen, Shao-Nong; Pauli, Guido F.

    2015-01-01

    This report describes a fragment-based approach to the examination of congeneric organic compounds by NMR spectroscopy. The method combines the classic interpretation of 1D- and 2D-NMR data sets with contemporary computer-assisted NMR analysis. Characteristic NMR profiles of key structural motifs were generated by 1H iterative full spin analysis and then joined together as building blocks to recreate the 1H NMR spectra of increasingly complex molecules. To illustrate the methodology described, a comprehensive analysis of steviol (1), seven steviol glycosides (2–8) and two structurally related isosteviol compounds (9, 10) was carried out. The study also assessed the potential impact of this method on relevant aspects of natural product research including structural verification, chemical dereplication, and mixture analysis. PMID:25714117

  18. Synthetic polycations with controlled charge density and molecular weight as building blocks for biomaterials.

    PubMed

    Kleinberger, Rachelle M; Burke, Nicholas A D; Zhou, Christal; Stöver, Harald D H

    2016-01-01

    A series of polycations prepared by RAFT copolymerization of N-(3-aminopropyl)methacrylamide hydrochloride (APM) and N-(2-hydroxypropyl)methacrylamide, with molecular weights of 15 and 40 kDa, and APM content of 10-75 mol%, were tested as building blocks for electrostatically assembled hydrogels such as those used for cell encapsulation. Complexation and distribution of these copolymers within anionic calcium alginate gels, as well as cytotoxicity, cell attachment, and cell proliferation on surfaces grafted with the copolymers were found to depend on composition and molecular weight. Copolymers with lower cationic charge density and lower molecular weight showed less cytotoxicity and cell adhesion, and were more mobile within alginate gels. These findings aid in designing improved polyelectrolyte complexes for use as biomaterials.

  19. Spectroscopic investigation of some building blocks of organic conductors: A comparative study

    NASA Astrophysics Data System (ADS)

    Mukherjee, V.; Yadav, T.

    2017-04-01

    Theoretical molecular structures and IR and Raman spectra of di and tetra methyl substituted tetrathiafulvalene and tetraselenafulvalene molecules have been studied. These molecules belong to the organic conductor family and are immensely used as building blocks of several organic conducting devices. The Hartree-Fock and density functional theory with exchange functional B3LYP have been employed for computational purpose. We have also performed normal coordinate analysis to scale the theoretical frequencies and to calculate potential energy distributions for the conspicuous assignments. The exciting frequency and temperature dependent Raman spectra have also presented. Optimization results reveal that the sulphur derivatives possess boat shape while selenium derivatives possess planner structures. Natural bond orbitals analysis has also been performed to study second order interaction between donors and acceptors and to compute molecular orbital occupancy and energy.

  20. A functional metasurface platform with unique building blocks: light manipulation and beam shaping

    NASA Astrophysics Data System (ADS)

    Forouzmand, Ali; Mosallaei, Hossein

    2016-09-01

    This paper presents an engineered metasurface which can serve functionalities such as anomalous bending, focusing, and beam shaping over the circularly polarized (CP) incident beam. The building block is a bilayer double split-loop resonators (DSLRs) where it can fully transmit the impinging light and control phase only by rotation of unit-cell and not by changing the structural parameters which can greatly facilitate the fabrication process. The mechanism behind this fascinating feature can be described as the conversion of an impinging CP incident beam into the opposite handedness and obtaining a geometrical phase shift equal to twice the rotating angle of DSLRs. It is illustrated that full transmission with 2π phase shift can be achieved with the proposed metasurface. Unique designs with helicity dependency to realize anomalous bending, bifunctional convergence/divergence, and flat-top beam creation with applying lossless beam shaping approach are presented.

  1. Multifunctional hybrids by combining ordered mesoporous materials and macromolecular building blocks.

    PubMed

    Soler-Illia, Galo J A A; Azzaroni, Omar

    2011-02-01

    This critical review presents and discusses the recent advances in complex hybrid materials that result from the combination of polymers and mesoporous matrices. Ordered mesoporous materials derived from supramolecular templating present high surface area and tailored pore sizes; pore surfaces can be further modified by organic, organometallic or even biologically active functional groups. This permits the creation of hybrid systems with distinct physical properties or chemical functions located in the framework walls, the pore surface, and the pore interior. Bringing polymeric building blocks into the game opens a new dimension: the possibility to create phase separated regions (functional domains) within the pores that can behave as "reactive pockets" of nanoscale size, with highly controlled chemistry and interactions within restricted volumes. The possibilities of combining "hard" and "soft" building blocks to yield these novel nanocomposite materials with tuneable functional domains ordered in space are potentially infinite. New properties are bound to arise from the synergy of both kinds of components, and their spatial location. The main object of this review is to report on new approaches towards functional polymer-inorganic mesostructured hybrids, as well as to discuss the present challenges in this flourishing research field. Indeed, the powerful concepts resulting from the synergy of sol-gel processing, supramolecular templating and polymer chemistry open new opportunities in the design of advanced functional materials: the tailored production of complex matter displaying spatially-addressed chemistry based on the control of chemical topology. Breakthrough applications are expected in the fields of sustainable energy, environment sensing and remediation, biomaterials, pharmaceutical industry and catalysis, among others (221 references).

  2. Intrinsic Folding Proclivities in Cyclic β-Peptide Building Blocks: Configuration and Heteroatom Effects Analyzed by Conformer-Selective Spectroscopy and Quantum Chemistry.

    PubMed

    Alauddin, Mohammad; Gloaguen, Eric; Brenner, Valérie; Tardivel, Benjamin; Mons, Michel; Zehnacker-Rentien, Anne; Declerck, Valérie; Aitken, David J

    2015-11-09

    This work describes the use of conformer-selective laser spectroscopy following supersonic expansion to probe the local folding proclivities of four-membered ring cyclic β-amino acid building blocks. Emphasis is placed on stereochemical effects as well as on the structural changes induced by the replacement of a carbon atom of the cycle by a nitrogen atom. The amide A IR spectra are obtained and interpreted with the help of quantum chemistry structure calculations. Results provide evidence that the building block with a trans-substituted cyclobutane ring has a predilection to form strong C8 hydrogen bonds. Nitrogen-atom substitution in the ring induces the formation of the hydrazino turn, with a related but distinct hydrogen-bonding network: the structure is best viewed as a bifurcated C8/C5 bond with the N heteroatom lone electron pair playing a significant acceptor role, which supports recent observations on the hydrazino turn structure in solution. Surprisingly, this study shows that the cis-substituted cyclobutane ring derivative also gives rise predominantly to a C8 hydrogen bond, although weaker than in the two former cases, a feature that is not often encountered for this building block.

  3. MOCHA/ISAIA: Building Blocks for Interoperability in a Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Cheung, C. Y.; Hanisch, R. J.; McGlynn, T. A.; Plante, R. L.; Shaya, E. J.

    2000-12-01

    Some basic building blocks must be put in place before we can realize the vision of a National or Global Virtual Observatory. MOCHA is a project that is building a prototype interoperability infrastructure for a Virtual Observatory. ISAIA is an effort that defines the astrophysics query profile to enables searches to networked astrophysics resources that have very different data structures. Both projects are funded by the NASA Applied Information Systems Research Program. We shall describe a joint demonstration by these two projects that involves four data centers: the Astronomical Data Center (ADC), the High Energy Astrophysics Science Archive Research Center (HEASARC), the Astronomical Digital Image Library (ADIL), the Space Telescope Science Institute (STScI); and the University of Maryland. We shall show how a positional query for astrophysical data in a region of arbitrary geometrical boundary can be carried out using these basic components. We shall also describe a scheme by which user software can be deployed to a data center to extend its services, and how the system will return to the researcher only the desired scientific results. This capability is very important for multispectral studies using the large all-sky surveys that reside in distributed data archives.

  4. A rare cationic building block that generates a new type of polyhedral network with "cross-linked" pto topology.

    PubMed

    Lusi, Matteo; Fechine, Pierre B A; Chen, Kai-Jie; Perry, John J; Zaworotko, Michael J

    2016-03-18

    A rare 8-connected cationic building block, [Cu2L8(μ-MF6)](2+) (L = pyridyl ligand, M = Si, Ti, Ge, Zr or Sn), enables the formation of a small cubicuboctahedral supramolecular building block, SBB, when complexed by 2,4,6-tris(4-pyridyl)pyridine. The coordination network resulting from fusing the square faces of the SBBs can be described as a pto topology in which half of the square faces are cross-linked by MF6(2-) moieties, and represents the first example of a new 3,5-c topology.

  5. A Library of Rad Hard Mixed-Voltage/Mixed-Signal Building Blocks for Integration of Avionics Systems for Deep Space

    NASA Technical Reports Server (NTRS)

    Mojarradi, M. M.; Blaes, B.; Kolawa, E. A.; Blalock, B. J.; Li, H. W.; Buck, K.; Houge, D.

    2001-01-01

    To build the sensor intensive system-on-a-chip for the next generation spacecrafts for deep space, Center for Integration of Space Microsystems at JPL (CISM) takes advantage of the lower power rating and inherent radiation resistance of Silicon on Insulator technology (SOI). We are developing a suite of mixed-voltage and mixed-signal building blocks in Honeywell's SOI process that can enable the rapid integration of the next generation avionics systems with lower power rating, higher reliability, longer life, and enhanced radiation tolerance for spacecrafts such as the Europa Orbiter and Europa Lander. The mixed-voltage building blocks are predominantly for design of adaptive power management systems. Their design centers around an LDMOS structure that is being developed by Honeywell, Boeing Corp, and the University of Idaho. The mixed-signal building blocks are designed to meet the low power, extreme radiation requirement of deep space applications. These building blocks are predominantly used to interface analog sensors to the digital CPU of the next generation avionics system on a chip. Additional information is contained in the original extended abstract.

  6. Development of a system of innovative insulated building blocks under energy related inventions grant. Quarterly progress report, ThermaLock Products, Inc., October 1, 1992--April 30, 1993

    SciTech Connect

    1993-04-05

    Progress is reported on research pertaining to insulated building blocks. Areas covered include coursing, the development of a stuffing machine, block fabrication, designs for earthquake testing, and sound tests.

  7. Antimicrobial activity of poly(acrylic acid) block copolymers.

    PubMed

    Gratzl, Günther; Paulik, Christian; Hild, Sabine; Guggenbichler, Josef P; Lackner, Maximilian

    2014-05-01

    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid-base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure.

  8. Syntheses and physical characterization of new aliphatic triblock poly(L-lactide-b-butylene succinate-b-L-lactide)s bearing soft and hard biodegradable building blocks.

    PubMed

    Ba, Chaoyi; Yang, Jing; Hao, Qinghui; Liu, Xiaoyun; Cao, Amin

    2003-01-01

    This study presents chemical syntheses and physical characterization of a new aliphatic poly(L-lactide-b-butylene succinate-b-L-lactide) triblock copolyester with soft and hard biodegradable building blocks. First, poly(butylene succinate) (PBS) prepolymers terminated with hydroxyl functional groups were synthesized through melt polycondensation from succinic acid and 1,4-butanediol. Further, a series of new PLLA-b-PBS-b-PLLA triblock copolyesters bearing various average PLLA block lengths were prepared via ring opening polymerization of L-lactide with the synthesized hydroxyl capped PBS prepolymer (Mn = 4.9 KDa) and stannous octanoate as the macroinitiator and catalyst, respectively. By means of GPC, NMR, FTIR, DSC, TGA, and wide-angle X-ray diffractometer (WAXD), the macromolecular structures and physical properties were intensively studied for these synthesized PBS prepolymer and PLLA-b-PBS-b-PLLA triblock copolyesters. 13C NMR and GPC experimental results confirmed the formation of sequential block structures without any detectable transesterification under the present experimental conditions, and the molecular weights of triblock copolyesters could be readily regulated by adjusting the feeding molar ratio of L-lactide monomer to the PBS macroinitiator. DSC measurements showed all single glass transitions, and their glass transition temperatures were found to be between those of PLLA and PBS, depending on the lengths of PLLA blocks. It was noteworthy that the segmental flexibilities of the hard PLLA blocks were found to be remarkably enhanced by the more flexible PBS block partner, and the PBS and PLLA building blocks were well mixed in the amorphous regions. Results of TGA analyses indicated that thermal degradation and stabilities of the PLLA blocks strongly depended on the average PLLA block lengths of triblock copolyesters. In addition, FTIR and WAXD results showed the coexistence of the assembled PLLA and PBS crystal structures when the average PLLA block

  9. hERG blocking potential of acids and zwitterions characterized by three thresholds for acidity, size and reactivity.

    PubMed

    Nikolov, Nikolai G; Dybdahl, Marianne; Jónsdóttir, Svava Ó; Wedebye, Eva B

    2014-11-01

    Ionization is a key factor in hERG K(+) channel blocking, and acids and zwitterions are known to be less probable hERG blockers than bases and neutral compounds. However, a considerable number of acidic compounds block hERG, and the physico-chemical attributes which discriminate acidic blockers from acidic non-blockers have not been fully elucidated. We propose a rule for prediction of hERG blocking by acids and zwitterionic ampholytes based on thresholds for only three descriptors related to acidity, size and reactivity. The training set of 153 acids and zwitterionic ampholytes was predicted with a concordance of 91% by a decision tree based on the rule. Two external validations were performed with sets of 35 and 48 observations, respectively, both showing concordances of 91%. In addition, a global QSAR model of hERG blocking was constructed based on a large diverse training set of 1374 chemicals covering all ionization classes, externally validated showing high predictivity and compared to the decision tree. The decision tree was found to be superior for the acids and zwitterionic ampholytes classes.

  10. Polyelectrolyte Stars and Cylindrical Brushes Made by ATRP: New Building Blocks in Nanotechnology

    NASA Astrophysics Data System (ADS)

    Plamper, Felix; Xu, Youyong; Yuan, Jiayin; Ballauff, Matthias; Müller, Axel H. E.

    Star polymers and cylindrical polymer brushes (CPBs), i.e. polymers possessing side groups densely grafted from a linear main chain, have attracted considerable experimental and theoretical interest over the past decade, owing to their peculiar solution and bulk properties. We have used the grafting-from approach via ATRP to synthesize well-defined star polymers and core—shell CPBs with homopolymer and block copolymer side chains. The diblock copolymer side chains may include combinations of soft-hard, hydrophilic-hydrophobic and crystalline-amorphous block segments. In particular, we have been interested in polyelectrolyte blocks; then the polymers resemble intramolecular spherical and cylindrical micelles, respectively. Star polymers of poly(acrylic acid) (PAA) and poly(N,N-dimethylaminoethyl methacrylate) (DMAEMA) were made using sugar- or silsesquioxane-based ATRP initiators. Their LCST and UCST phase behaviour depends on pH, counterion charge, temperature, and light. PDMAEMA CPBs react in a similar way, and on addition of trivalent counterions they even form helical structures. We have also synthesized hybrid nanowires of semiconducting CdS and CdSe or nanomagnets of γ-Fe2O3 inside the PAA core of CPBs. Here, we present novel water-soluble and biocompatible silica nanowires based on CPBs. They have a core consisting of a silsesquioxane network of crosslinked poly(3-acryloylpropyl trimethoxysilane) (PAPTS) and a shell of poly(oligoe-thyleneglycol methacrylate) (POEGMA). Sequential ATRP of APTS and OEGMA initiated by a polyinitiator backbone (DP = 3,200) was carried out in benzene. Due to the cylindrical shape of the brushes the functional TMS moieties were arranged into a 1D manner and then crosslinked via alkaline condensation, rendering the rigid core—shell hybrid CPBs. Finally, uniform silica nanowires were achieved by the simultaneous removal of the hybrid CPB template via pyrolysis. The length as well as the diameter of silica nanowires are well-defined.

  11. Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C 2-symmetric building block: a strategy for the synthesis of decanolide natural products

    PubMed Central

    Kunz, Oliver

    2013-01-01

    Summary Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation. PMID:24367418

  12. Three-dimensional {Co(3+)-Zn2+} and {Co(3+)-Cd2+} networks originated from carboxylate-rich building blocks: syntheses, structures, and heterogeneous catalysis.

    PubMed

    Kumar, Girijesh; Gupta, Rajeev

    2013-10-07

    The present work shows the utilization of Co(3+) complexes appended with either para- or meta-arylcarboxylic acid groups as the molecular building blocks for the construction of three-dimensional {Co(3+)-Zn(2+)} and {Co(3+)-Cd(2+)} heterobimetallic networks. The structural characterizations of these networks show several interesting features including well-defined pores and channels. These networks function as heterogeneous and reusable catalysts for the regio- and stereoselective ring-opening reactions of various epoxides and size-selective cyanation reactions of assorted aldehydes.

  13. Synthesis and NMR studies of malonyl-linked glycoconjugates of N-(2-aminoethyl)glycine. Building blocks for the construction of combinatorial glycopeptide libraries

    PubMed Central

    Nörrlinger, Markus; Hafner, Sven

    2016-01-01

    Summary Four glycoconjugate building blocks for the construction of combinatorial PNA like glycopeptide libraries were prepared in 75–79% yield by condensing tert-butyl N-[2-(N-9-fluorenylmethoxycarbonylamino)ethyl]glycinate (AEG) 5 with 3-oxo-3-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosylamino)- (6a), 3-oxo-3-(β-D-galactopyranosylamino)- (6b), 3-oxo-3-(2-acetamido-2-deoxy-3,4,6-tetra-O-acetyl-β-D-glucopyranosylamino)- (6c) and 3-oxo-3-(2-acetamido-2-deoxy-3,4,6-tetra-O-acetyl-β-D-galactopyranosylamino)propanoic acid (6d), respectively. The resulting AEG glycoconjugates 1a–d were converted into the corresponding free acids 2a–d in 97–98% yield by treatment with aqueous formic acid. The Fmoc group of compound 1c was removed and the intermediate amine 9 was condensed with 2a to afford the corresponding glycosylated AEG dipeptide 4 in 58% yield. All glycoconjugate building blocks showed the presence of cis and trans rotamers. Compounds 1a, 1b and 4 were subjected to temperature dependent 1H NMR spectroscopy in order to determine the coalescence temperature which resulted in calculated rotation barriers of 17.9–18.3 kcal/mol for the rotamers. PMID:27829900

  14. SiC Multi-Chip Power Modules as Power-System Building Blocks

    NASA Technical Reports Server (NTRS)

    Lostetter, Alexander; Franks, Steven

    2007-01-01

    The term "SiC MCPMs" (wherein "MCPM" signifies "multi-chip power module") denotes electronic power-supply modules containing multiple silicon carbide power devices and silicon-on-insulator (SOI) control integrated-circuit chips. SiC MCPMs are being developed as building blocks of advanced expandable, reconfigurable, fault-tolerant power-supply systems. Exploiting the ability of SiC semiconductor devices to operate at temperatures, breakdown voltages, and current densities significantly greater than those of conventional Si devices, the designs of SiC MCPMs and of systems comprising multiple SiC MCPMs are expected to afford a greater degree of miniaturization through stacking of modules with reduced requirements for heat sinking. Moreover, the higher-temperature capabilities of SiC MCPMs could enable operation in environments hotter than Si-based power systems can withstand. The stacked SiC MCPMs in a given system can be electrically connected in series, parallel, or a series/parallel combination to increase the overall power-handling capability of the system. In addition to power connections, the modules have communication connections. The SOI controllers in the modules communicate with each other as nodes of a decentralized control network, in which no single controller exerts overall command of the system. Control functions effected via the network include synchronization of switching of power devices and rapid reconfiguration of power connections to enable the power system to continue to supply power to a load in the event of failure of one of the modules. In addition to serving as building blocks of reliable power-supply systems, SiC MCPMs could be augmented with external control circuitry to make them perform additional power-handling functions as needed for specific applications: typical functions could include regulating voltages, storing energy, and driving motors. Because identical SiC MCPM building blocks could be utilized in a variety of ways, the cost

  15. Quantum Simulation with Circuit-QED Lattices: from Elementary Building Blocks to Many-Body Theory

    NASA Astrophysics Data System (ADS)

    Zhu, Guanyu

    Recent experimental and theoretical progress in superconducting circuits and circuit QED (quantum electrodynamics) has helped to develop high-precision techniques to control, manipulate, and detect individual mesoscopic quantum systems. A promising direction is hence to scale up from individual building blocks to form larger-scale quantum many-body systems. Although realizing a scalable fault-tolerant quantum computer still faces major barriers of decoherence and quantum error correction, it is feasible to realize scalable quantum simulators with state-of-the-art technology. From the technological point of view, this could serve as an intermediate stage towards the final goal of a large-scale quantum computer, and could help accumulating experience with the control of quantum systems with a large number of degrees of freedom. From the physical point of view, this opens up a new regime where condensed matter systems can be simulated and studied, here in the context of strongly correlated photons and two-level systems. In this thesis, we mainly focus on two aspects of circuit-QED based quantum simulation. First, we discuss the elementary building blocks of the quantum simulator, in particular a fluxonium circuit coupled to a superconducting resonator. We show the interesting properties of the fluxonium circuit as a qubit, including the unusual structure of its charge matrix elements. We also employ perturbation theory to derive the effective Hamiltonian of the coupled system in the dispersive regime, where qubit and the photon frequencies are detuned. The observables predicted with our theory, including dispersive shifts and Kerr nonlinearity, are compared with data from experiments, such as homodyne transmission and two-tone spectroscopy. These studies also relate to the problem of detection in a circuit-QED quantum simulator. Second, we study many-body physics of circuit-QED lattices, serving as quantum simulators. In particular, we focus on two different

  16. Properties of non-IPR fullerene films versus size of the building blocks.

    PubMed

    Löffler, Daniel; Ulas, Seyithan; Jester, Stefan-Sven; Weis, Patrick; Böttcher, Artur; Kappes, Manfred M

    2010-09-28

    This perspective focuses on the cage size dependent properties of novel solid fullerene nanofilms grown by soft-landing of mass-selected C(n)(+) (48, 50, 52, 54, 56, 58, 62, 64, 66 and 68) onto room temperature graphite surfaces under ultra-high vacuum conditions. Such non-isolated-pentagon-ring (non-IPR) fullerene materials are not accessible to standard fullerene preparation methods. The component molecular building blocks of non-IPR films were generated by electron impact induced ionization/fragmentation of sublimed IPR-C(70)(D(5h)) (-->C(n) (n = 68, 66, 64, 62)) or IPR-C(60)(I(h)) (-->C(n) (n = 58, 56, 54, 52, 50)). Non-IPR fullerene films on graphite grow via formation of dendritic C(n) aggregates, whereas deposition of IPR fullerenes under analogous conditions (via deposition of unfragmented C(60)(+) and C(70)(+)) leads to compact islands. The latter are governed by weak van der Waals cage-cage interactions. In contrast, the former are stabilized by covalent intercage bonds as mediated by the non-IPR sites (primarily adjacent pentagon pairs, AP). A significant fraction of the deposited non-IPR C(n) cages can be intactly (re)sublimed by heating. The corresponding mean desorption activation energies, E(des), increase from 2.1 eV for C(68) up to 2.6 eV for C(50). The densities of states in the valence band regions (DOS), surface ionization potentials (sIP) and HOMO-LUMO gaps (Delta) of semiconducting non-IPR films were measured and found to vary strongly with cage size. Overall, the n-dependencies of these properties can be interpreted in terms of covalently interconnected oligomeric structures comprising the most stable (neutral) C(n) isomers-as determined from density functional theory (DFT) calculations. Non-IPR fullerene films are the first known examples of elemental cluster materials in which the cluster building blocks are covalently but reversibly interconnected.

  17. "Science SQL" as a Building Block for Flexible, Standards-based Data Infrastructures

    NASA Astrophysics Data System (ADS)

    Baumann, Peter

    2016-04-01

    We have learnt to live with the pain of separating data and metadata into non-interoperable silos. For metadata, we enjoy the flexibility of databases, be they relational, graph, or some other NoSQL. Contrasting this, users still "drown in files" as an unstructured, low-level archiving paradigm. It is time to bridge this chasm which once was technologically induced, but today can be overcome. One building block towards a common re-integrated information space is to support massive multi-dimensional spatio-temporal arrays. These "datacubes" appear as sensor, image, simulation, and statistics data in all science and engineering domains, and beyond. For example, 2-D satellilte imagery, 2-D x/y/t image timeseries and x/y/z geophysical voxel data, and 4-D x/y/z/t climate data contribute to today's data deluge in the Earth sciences. Virtual observatories in the Space sciences routinely generate Petabytes of such data. Life sciences deal with microarray data, confocal microscopy, human brain data, which all fall into the same category. The ISO SQL/MDA (Multi-Dimensional Arrays) candidate standard is extending SQL with modelling and query support for n-D arrays ("datacubes") in a flexible, domain-neutral way. This heralds a new generation of services with new quality parameters, such as flexibility, ease of access, embedding into well-known user tools, and scalability mechanisms that remain completely transparent to users. Technology like the EU rasdaman ("raster data manager") Array Database system can support all of the above examples simultaneously, with one technology. This is practically proven: As of today, rasdaman is in operational use on hundreds of Terabytes of satellite image timeseries datacubes, with transparent query distribution across more than 1,000 nodes. Therefore, Array Databases offering SQL/MDA constitute a natural common building block for next-generation data infrastructures. Being initiator and editor of the standard we present principles

  18. Creating functional sophistication from simple protein building blocks, exemplified by factor H and the regulators of complement activation.

    PubMed

    Makou, Elisavet; Herbert, Andrew P; Barlow, Paul N

    2015-10-01

    Complement control protein modules (CCPs) occur in numerous functionally diverse extracellular proteins. Also known as short consensus repeats (SCRs) or sushi domains each CCP contains approximately 60 amino acid residues, including four consensus cysteines participating in two disulfide bonds. Varying in length and sequence, CCPs adopt a β-sandwich type fold and have an overall prolate spheroidal shape with N- and C-termini lying close to opposite poles of the long axis. CCP-containing proteins are important as cytokine receptors and in neurotransmission, cell adhesion, blood clotting, extracellular matrix formation, haemoglobin metabolism and development, but CCPs are particularly well represented in the vertebrate complement system. For example, factor H (FH), a key soluble regulator of the alternative pathway of complement activation, is made up entirely from a chain of 20 CCPs joined by short linkers. Collectively, therefore, the 20 CCPs of FH must mediate all its functional capabilities. This is achieved via collaboration and division of labour among these modules. Structural studies have illuminated the dynamic architectures that allow FH and other CCP-rich proteins to perform their biological functions. These are largely the products of a highly varied set of intramolecular interactions between CCPs. The CCP can act as building block, spacer, highly versatile recognition site or dimerization mediator. Tandem CCPs may form composite binding sites or contribute to flexible, rigid or conformationally 'switchable' segments of the parent proteins.

  19. Production of carbohydrate building blocks from red seaweed polysaccharides. Efficient conversion of galactans into C-glycosyl aldehydes.

    PubMed

    Ducatti, Diogo R B; Massi, Alessandro; Noseda, Miguel D; Duarte, Maria Eugênia R; Dondoni, Alessandro

    2009-02-07

    Agarans and carrageenans are abundant natural polysaccharides which are obtained on a large scale by water extraction from a variety of red seaweeds. These galactans, in addition to being valuable products for the pharmaceutical and food industries, are low cost starting materials for the preparation of useful and rare carbohydrate-based building blocks whose access by total synthesis is difficult and expensive. The semisynthesis of two sets of C-glycosyl aldehydes with l- and d-configuration from agarose and kappa-carrageenan respectively is described. Succinctly, the partial acid-catalyzed mercaptolysis of the two galactans under mild conditions afforded agarobiose and carrabiose (beta-d-Galp-(1-->4)-3,6-anhydro-aldehydo-l- and d-galactose, respectively) derivatives. Complete depolymerization of agarose and kappa-carrageenan under harsher conditions produced 3,6-anhydro l- and d-galactose aldehyde derivatives. Chain shortening of these products via alditol formation and oxidative carbon-carbon bond cleavage furnished C-formyl alpha-l- and alpha-d-threofuranosides. The above C-glycosyl aldehydes were all prepared on a meaningful preparative scale starting from gram quantities of galactans. Finally, a new procedure for the preparation of the 2,3-O-benzyl l-threofuranose was established by Baeyer-Villiger oxidation of the benzylated C-formyl alpha-l-threofuranoside here prepared from agarose.

  20. The Building Blocks of Digital Media Literacy: Socio-Material Participation and the Production of Media Knowledge

    ERIC Educational Resources Information Center

    Dezuanni, Michael

    2015-01-01

    This article outlines the knowledge and skills students develop when they engage in digital media production and analysis in school settings. The metaphor of "digital building blocks" is used to describe the material practices, conceptual understandings and production of knowledge that lead to the development of digital media literacy.…

  1. The Development of Logico-Mathematical Knowledge in a Block-Building Activity at Ages 1-4

    ERIC Educational Resources Information Center

    Kamii, Constance; Miyakawa, Yoko; Kato, Yasuhiko

    2004-01-01

    To study the developmental interrelationships among various aspects of logico-mathematical knowledge, 80 one- to 4-year-olds were individually asked to build "something tall" with 20 blocks. Percentages of new and significant behaviors increased with age and were analyzed in terms of the development of logico-mathematical relationships. It was…

  2. Programming the assembly of two- and three-dimensional architectures with DNA and nanoscale inorganic building blocks.

    PubMed

    Mirkin, C A

    2000-05-29

    The use of biochemical molecular recognition principles for the assembly of nanoscale inorganic building blocks into macroscopic functional materials constitutes a new frontier in science. This article details efforts pertaining to the use of sequence-specific DNA hybridization events and novel inorganic surface coordination chemistry to control the formation of both two- and three-dimensional functional architectures.

  3. Playing with structures at the nanoscale: designing catalysts by manipulation of clusters and nanocrystals as building blocks.

    PubMed

    Cargnello, Matteo; Fornasiero, Paolo; Gorte, Raymond J

    2013-12-02

    The purpose of this Concept is to highlight some of the most recent and promising methods for the preparation of tailored catalysts by designing and preparing the component building blocks and by assembling them in a controlled fashion. We want to emphasize how rational design and synthesis of catalysts must be coupled to precise catalytic and structural characterization of the systems in an ideal feedback loop. New catalyst design and preparation techniques, dictated by information about the active sites that the specific application requires, are frequently available. The building blocks for developing these novel catalysts include colloidal methods for the preparation of uniform nanostructures, physical methods for rational assembly of the building blocks (Langmuir-Blodgett, liquid-air self-assembly), and development of rational interactions between the building blocks for enhanced activity of the assemblies. These methods, which apply techniques normally used in other fields of nanotechnology to catalysis, offer exciting opportunities to help improve currently available catalytic systems in terms of activity, stability and selectivity.

  4. Use of shock block transmitters in the structural rehabilitation of historical buildings in Calabria and Sicily

    SciTech Connect

    Bianco, Alessia; Candela, Michele; Fonti, Roberta

    2008-07-08

    Many old and historical masonry buildings, located in the Calabrian and Sicilian areas near the strait of Messina, are affected by typical pattern of cracks, which are not produced by previous earthquakes. These cracks in the masonry walls are characterized by a quasi-vertical trend with constant width. The careful examination of the crack distribution allows to clearly identify the diagnosis: the damage is caused by the sinking due to a horizontal movement of translation of the ground, which is an evident effect of creep phenomena in the soil, so-called 'solifluxion'. This paper, after showing this geological pathology, proposes an innovative strategy of intervention, which consists of the use of 'oleo-dynamic' devices, so-called shock block transmitters, providing different degrees of restraint, according to the loading conditions. In addition, in case of earthquake, an important part of the in-put seismic energy can be dissipated. The strategy of application of this system to the building consists of the subdivision of each masonry wall in two different parts, which are physically separated by the cracks. Each wall portion must be consolidated separately and the different parts of walls behave as statically independent each other, so that they can move independently during the serviceability conditions. The connection among the walls composing the whole structural organism is given by metal tie-rods equipped with 'oleo dynamic' devices, which allows, in a given range, the horizontal sliding in case of slow movement due to the phenomenon of 'solifluxion'. Contrary, in case of dynamic and fast movements, such as the ones produced by an earthquake, each 'oleo dynamic' device provides a fully restraint effect and, as a consequence, the tie-rods behave in the classical way.

  5. α-Fluorovinyl Weinreb Amides and α- Fluoroenones from a Common Fluorinated Building Block

    PubMed Central

    Ghosh, Arun K.; Banerjee, Shaibal; Sinha, Saikat; Kang, Soon Bang; Zajc, Barbara

    2009-01-01

    Synthesis and reactivity of N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfonyl)fluoroacetamide, a building block for Julia olefination, is reported. This reagent undergoes condensation reactions with aldehydes and cyclic ketones, to give α-fluorovinyl Weinreb amides. Olefination reactions proceed under mild, DBU-mediated conditions, or in the presence of NaH. DBU-mediated condensations proceed with either E or Z-selectivity, depending upon reaction conditions, whereas NaH-mediated reactions are ≥98% Z-stereoselective. Conversion of the Weinreb amide moiety in N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfanyl)fluoroacetamide to ketones, followed by oxidation, resulted in another set of olefination reagents, namely (1,3-benzothiazol-2-ylsulfonyl)fluoromethyl phenyl and propyl ketones. In the presence of DBU, these compounds react with aldehydes tested to give α-fluoroenones with high Z-selectivity. The use of N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfanyl)fluoroacetamide as a common fluorinated intermediate in the synthesis of α-fluorovinyl Weinreb amides and α-fluoroenones has been demonstrated. Application of the Weinreb amide to α-fluoro allyl amine synthesis is also shown. PMID:19361189

  6. Search for water and life's building blocks in the universe: A summary

    NASA Astrophysics Data System (ADS)

    Ehrenfreund, Pascale; Kwok, Sun; Bergin, Edwin

    2015-08-01

    Water and organic compounds are essential ingredients for life on Earth and possibly elsewhere. In gaseous form water acts as a coolant that allows interstellar gas clouds to collapse to form stars, whereas water ice covers small dust particles that agglomerate to form planetesimals and planets. The variety of organic compounds identified in interstellar and circumstellar regions reflects complex reaction schemes in the gaseous and icy/solid state. Interstellar volatiles and refractory materials were processed and radially mixed within the protostellar disk from which our solar system formed. But the dynamic solar nebula was also a source for new materials and the search for water and life’s building blocks on terrestrial planets, most of the outer-solar-system satellites as well as small solar system bodies reveals exciting new findings. The analysis of small bodies and their fragments, meteorites and interplanetary dust particles, sheds lights onto the extraterrestrial delivery process of prebiotic molecules to young planets and the pathways to life’s origin on Earth and possibly elsewhere. We summarize the results of invited and contributed papers of this Focus Meeting which will allow us to better assess the habitability of objects in our solar system and provide constraints for exoplanets.

  7. Probing the bioactivity-relevant chemical space of robust reactions and common molecular building blocks.

    PubMed

    Hartenfeller, Markus; Eberle, Martin; Meier, Peter; Nieto-Oberhuber, Cristina; Altmann, Karl-Heinz; Schneider, Gisbert; Jacoby, Edgar; Renner, Steffen

    2012-05-25

    In the search for new bioactive compounds, there is a trend toward increasingly complex compound libraries aiming to target the demanding targets of the future. In contrast, medicinal chemistry and traditional library design rely mainly on a small set of highly established and robust reactions. Here, we probe a set of 58 such reactions for their ability to sample the chemical space of known bioactive molecules, and the potential to create new scaffolds. Combined with ~26,000 common available building blocks, the reactions retrieve around 9% of a scaffold-diverse set of compounds active on human target proteins covering all major pharmaceutical target classes. Almost 80% of generated scaffolds from virtual one-step synthesis products are not present in a large set of known bioactive molecules for human targets, indicating potential for new discoveries. The results suggest that established synthesis resources are well suited to cover the known bioactivity-relevant chemical space and that there are plenty of unexplored regions accessible by these reactions, possibly providing valuable "low-hanging fruit" for hit discovery.

  8. Nanocluster building blocks of artificial square spin ice: Stray-field studies of thermal dynamics

    SciTech Connect

    Pohlit, Merlin Porrati, Fabrizio; Huth, Michael; Müller, Jens

    2015-05-07

    We present measurements of the thermal dynamics of a Co-based single building block of an artificial square spin ice fabricated by focused electron-beam-induced deposition. We employ micro-Hall magnetometry, an ultra-sensitive tool to study the stray field emanating from magnetic nanostructures, as a new technique to access the dynamical properties during the magnetization reversal of the spin-ice nanocluster. The obtained hysteresis loop exhibits distinct steps, displaying a reduction of their “coercive field” with increasing temperature. Therefore, thermally unstable states could be repetitively prepared by relatively simple temperature and field protocols allowing one to investigate the statistics of their switching behavior within experimentally accessible timescales. For a selected switching event, we find a strong reduction of the so-prepared states' “survival time” with increasing temperature and magnetic field. Besides the possibility to control the lifetime of selected switching events at will, we find evidence for a more complex behavior caused by the special spin ice arrangement of the macrospins, i.e., that the magnetic reversal statistically follows distinct “paths” most likely driven by thermal perturbation.

  9. A LEON2&3 Emulation Board Qualified for Space Programs Based on Reusable Building Blocks

    NASA Astrophysics Data System (ADS)

    Caleno, Mauro; Quere, Gregory; Chenu, Xavier

    2014-08-01

    ESA/ESTEC has granted Airbus Defense and Space a study for the development of a versatile LEON2 and LEON3 emulation board hosted on a COTS FPGA board.The LEON Emulation Board (LEB) is a component for System Simulators used as Software Validation Facilities and Operational Simulators. It is an alternative to the full software simulation of the LEON processor; additionally, because it embeds the actual VHDL of the LEON processor, it is fully representative and delivers a performance higher than the instruction-set software simulators.The LEB enables simulating in software the functions of Systems on Chip not already embedded in the LEB. It is available in 3 configurations for the LEON2 FT and the LEON3. Moreover, as it is built around a set of reusable simulation building blocks (VHDL + software driver), it can easily be reassembled to emulate more accurately different Systems on Chips (SoC).This paper presents the key functions of the LEB, its performance, applications and potential future developments.

  10. Structural Influence on Superatomic Orbitals of Typical Gold Nanostructure Building Blocks

    NASA Astrophysics Data System (ADS)

    Jiang, Wanrun; Gao, Yang; Xu, Dexuan; Liu, Fang; Wang, Zhigang

    2016-10-01

    We compared superatomic orbitals mainly contributed by 6s atomic orbitals among spherical core-shell cluster Au13, hexagonal plane Au7 and a (5,5) nanotube segment Au35 through first-principles density functional theory calculations. The compatibility between geometry and orbital morphology influences both the presence and the energy level order of particular superatomic orbitals. Taking Au13 as a reference, which possesses a regular configuration of 1S 21P 61D 5, the hexagonal Au7 in 1S 21P 41D 1 lacks the 1P occupied superatomic orbital which is distributed out of the structural plane. Different from the nearly degenerated five occupied 1D orbitals in Au13, Au35 in 1S 21P 61D 101F 101G 61H 1 shows energy separations over 4.0 eV between split 1D regions and 1F regions according to the preference of tubular geometry to different orbital morphologies. The structural reliance of the electronic structure revealed by these typical building blocks might be informative for bottom-up design and fabrication of nanoscale devices based on a gold nanostructure and contributes to the variety and operability of nanoscale materials.

  11. Lunar and Planetary Science XXXV: Terrestrial Planets: Building Blocks and Differentiation

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Terrestrial Planets: Building Blocks and Differentiation: included the following topics:Magnesium Isotopes in the Earth, Moon, Mars, and Pallasite Parent Body: High-Precision Analysis of Olivine by Laser-Ablation Multi-Collector ICPMS; Meteoritic Constraints on Collision Rates in the Primordial Asteroid Belt and Its Origin; New Constraints on the Origin of the Highly Siderophile Elements in the Earth's Upper Mantle; Further Lu-Hf and Sm-Nd Isotopic Data on Planetary Materials and Consequences for Planetary Differentiation; A Deep Lunar Magma Ocean Based on Neodymium, Strontium and Hafnium Isotope Mass Balance Partial Resetting on Hf-W System by Giant Impacts; On the Problem of Metal-Silicate Equilibration During Planet Formation: Significance for Hf-W Chronometry ; Solid Metal-Liquid Metal Partitioning of Pt, Re, and Os: The Effect of Carbon; Siderophile Element Abundances in Fe-S-Ni-O Melts Segregated from Partially Molten Ordinary Chondrite Under Dynamic Conditions; Activity Coefficients of Silicon in Iron-Nickel Alloys: Experimental Determination and Relevance for Planetary Differentiation; Reinvestigation of the Ni and Co Metal-Silicate Partitioning; Metal/Silicate Paritioning of P, Ga, and W at High Pressures and Temperatures: Dependence on Silicate Melt Composition; and Closure of the Fe-S-Si Liquid Miscibility Gap at High Pressure and Its Implications for Planetary Core Formation.

  12. Cellularized microcarriers as adhesive building blocks for fabrication of tubular tissue constructs

    PubMed Central

    Twal, Waleed O.; Klatt, Sandra C.; Harikrishnan, Keerthi; Gerges, Ebtesam; Cooley, Marion A.; Trusk, Thomas C.; Zhou, Boran; Gabr, Mohamed G.; Shazly, Tarek; Lessner, Susan M.; Markwald, Roger R.; Argraves, W. Scott

    2013-01-01

    To meet demands of vascular reconstruction, there is a need for prosthetic alternatives to natural blood vessels. Here we explored a new conduit fabrication approach. Macroporous, gelatin microcarriers laden with human umbilical vein endothelial cells and aortic smooth muscle cells were dispensed into tubular agarose molds and found to adhere to form living tubular tissues. The ability of cellularized microcarriers to adhere to one another involved cellular and extracellular matrix bridging that included the formation of epithelium-like cell layers lining the lumenal and ablumenal surfaces of the constructs and the deposition of collagen and elastin fibers. The tubular tissues behaved as elastic solids, with a uniaxial mechanical response that is qualitatively similar to that of native vascular tissues and consistent with their elastin and collagen composition. Linearized measures of the mechanical response of the fabricated tubular tissues at both low and high strains was observed to increase with duration of static culture, with no significant loss of stiffness following decellularization. The findings highlight the utility of cellularized macroporous gelatin microcarriers as self-adhering building blocks for the fabrication of living tubular structures. PMID:23943070

  13. Three-dimensional tissues using human pluripotent stem cell spheroids as biofabrication building blocks.

    PubMed

    Lin, Haishuang; Li, Qiang; Lei, Yuguo

    2017-03-13

    A recently emerged approach for tissue engineering is to biofabricate tissues using cellular spheroids as building blocks. Human pluripotent stem cells (hPSCs), including human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), can be cultured to generate large numbers of cells and presumably be differentiated into all the cell types of human body in vitro, thus are ideal cell source for biofabrication. We previously developed a hydrogel-based cell culture system that can economically produce large numbers of hPSC spheroids. With hPSCs and this culture system, there are two potential methods to biofabricate a desired tissue. In Method 1, hPSC spheroids are first utilized to biofabricate a hPSC tissue that is subsequently differentiated into the desired tissue. In Method 2, hPSC spheroids are first converted into tissue spheroids in the hydrogel-based culture system and the tissue spheroids are then utilized to biofabricate the desired tissue. In this paper, we systematically measured the fusion rates of hPSC spheroids without and with differentiation toward cortical and midbrain dopaminergic neurons and found spheroids' fusion rates dropped sharply as differentiation progressed. We found Method 1 was appropriated for biofabricating neural tissues.

  14. Linking dwarf galaxies to halo building blocks with the most metal-poor star in Sculptor.

    PubMed

    Frebel, Anna; Kirby, Evan N; Simon, Joshua D

    2010-03-04

    Current cosmological models indicate that the Milky Way's stellar halo was assembled from many smaller systems. On the basis of the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. The discovery of an extremely iron-poor star (S1020549) in the Sculptor dwarf galaxy based on a medium-resolution spectrum cast some doubt on this conclusion. Verification of the iron-deficiency, however, and measurements of additional elements, such as the alpha-element Mg, are necessary to demonstrate that the same type of stars produced the metals found in dwarf galaxies and the Galactic halo. Only then can dwarf galaxy stars be conclusively linked to early stellar halo assembly. Here we report high-resolution spectroscopic abundances for 11 elements in S1020549, confirming its iron abundance of less than 1/4,000th that of the Sun, and showing that the overall abundance pattern follows that seen in low-metallicity halo stars, including the alpha-elements. Such chemical similarity indicates that the systems destroyed to form the halo billions of years ago were not fundamentally different from the progenitors of present-day dwarfs, and suggests that the early chemical enrichment of all galaxies may be nearly identical.

  15. Dual-Functional Hydrazide-Reactive and Anhydride-Containing Oligomeric Hydrogel Building Blocks.

    PubMed

    Kascholke, Christian; Loth, Tina; Kohn-Polster, Caroline; Möller, Stephanie; Bellstedt, Peter; Schulz-Siegmund, Michaela; Schnabelrauch, Matthias; Hacker, Michael C

    2017-03-13

    Biomimetic hydrogels are advanced biomaterials that have been developed following different synthetic routes. Covalent postfabrication functionalization is a promising strategy to achieve efficient matrix modification decoupled of general material properties. To this end, dual-functional macromers were synthesized by free radical polymerization of maleic anhydride with diacetone acrylamide (N-(1,1-dimethyl-3-oxobutyl)acrylamide) and pentaerythritol diacrylate monostearate. Amphiphilic oligomers (Mn < 7.5 kDa) with anhydride contents of 7-20% offered cross-linking reactivity to yield rigid hydrogels with gelatinous peptides (E = 4-13 kPa) and good cell adhesion properties. Mildly reactive methyl ketones as second functionality remained intact during hydrogel formation and potential of covalent matrix modification was shown using hydrazide and hydrazine model compounds. Successful secondary dihydrazide cross-linking was demonstrated by an increase of hydrogel stiffness (>40%). Efficient hydrazide/hydrazine immobilization depending on solution pH, hydrogel ketone content as well as ligand concentration for bioconjugation was shown and reversibility of hydrazone formation was indicated by physiologically relevant hydrazide release over 7 days. Proof-of-concept experiments with hydrazido-functionalized hyaluronan demonstrated potential for covalent aECM immobilization. The presented dual-functional macromers have perspective as reactive hydrogel building blocks for various biomedical applications.

  16. Intrinsic Optical Activity and Environmental Perturbations: Solvation Effects in Chiral Building Blocks

    NASA Astrophysics Data System (ADS)

    Lemler, Paul M.; Vaccaro, Patrick

    2016-06-01

    The non-resonant interaction of electromagnetic radiation with an isotropic ensemble of chiral molecules, which causes the incident state of linear polarization to undergo a signed rotation, long has served as a metric for gauging the enantiomeric purity of asymmetric syntheses. While the underlying phenomenon of circular birefringence (CB) typically is probed in the condensed phase, recent advances in ultrasensitive circular-differential detection schemes, as exemplified by the techniques of Cavity Ring-Down Polarimetry (CRDP), have permitted the first quantitative analyses of such processes to be performed in rarefied media. Efforts to extend vapor-phase investigations of CB to new families of chiral substrates will be discussed, with particular emphasis directed towards the elucidation of intrinsic (e.g., solvent-free) properties and their mediation by environmental perturbations (e.g., solvation). Specific species targeted by this work will include the stereoselective building blocks phenylpropylene oxide and α-methylbenzyl amine, both of which exhibit pronounced solvent-dependent changes in measured optical activity. The nature of chiroptical response in different environments will be highlighted, with quantum-chemical calculations serving to unravel the structural and electronic provenance of observed behavior.

  17. Building blocks of self-control: increased tolerance for delay with bundled rewards.

    PubMed Central

    Ainslie, George; Monterosso, John R

    2003-01-01

    Impulsive choice can be defined as temporary preference for a smaller-sooner reward (SS) over a larger-later reward (LL). Hyperbolic discounting implies that impulsive choices will occur less when organisms choose between a series of SSs versus LLs all at once than when they choose between single SS versus LL pairs. Eight rats were exposed to two conditions of an intertemporal choice paradigm using sucrose solution as reward. In both conditions, the LL was 150 microl delayed by 3 s, while the SS was an immediate reward that ranged from 25-150 microl across sessions. Preference for the LL was greater when the chosen reward was automatically delivered three times in succession (bundled) than when it was chosen singly and delivered after each choice. For each of the 8 rats, the estimated SS amount that produced indifference was higher in the bundled condition than in the single condition. Because bundling in humans may be based on the perception that one's current choice is predictive of future choices, the data presented here may demonstrate an important building block of self-control. PMID:12696740

  18. Probing the Conformational Landscape of Polyether Building Blocks in Supersonic Jets

    NASA Astrophysics Data System (ADS)

    Bocklitz, Sebastian; Hewett, Daniel M.; Zwier, Timothy S.; Suhm, Martin A.

    2016-06-01

    Polyethylene oxides (Polyethylene glycoles) and their phenoxy-capped analogs represent a prominent class of important polymers that are highly used as precursor molecules in supramolecular reactions. After a detailed study on the simplest representative (1,2-dimethoxyethane) [1], we present results on oligoethylene oxides with increasing chain lengths obtained by spontaneous Raman scattering in a supersonic jet. Through variation of stagnation pressure, carrier gas, nozzle distance and temperature we gain information on the conformational landscape as well as the mutual interconversion of low energy conformers. The obtained results are compared to state-of-the-art quantum chemical calculations. Additionally, we present UV as well as IR-UV and UV-UV double resonance studies on 1-methoxy-2-phenoxyethane in a supersonic jet. These complementary techniques allow for conformationally selective electronic and vibrational spectra in a closely related conformational landscape. [1] S. Bocklitz, M. A. Suhm, Constraining the Conformational Landscape of a Polyether Building Block by Raman Jet Spectroscopy, Z. Phys. Chem. 2015, 229, 1625-1648.

  19. The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge.

    PubMed

    Ferraro, F R; Dalessandro, E; Mucciarelli, A; Beccari, G; Rich, R M; Origlia, L; Lanzoni, B; Rood, R T; Valenti, E; Bellazzini, M; Ransom, S M; Cocozza, G

    2009-11-26

    Globular star clusters are compact and massive stellar systems old enough to have witnessed the entire history of our Galaxy, the Milky Way. Although recent results suggest that their formation may have been more complex than previously thought, they still are the best approximation to a stellar population formed over a relatively short timescale (less than 1 Gyr) and with virtually no dispersion in the iron content. Indeed, only one cluster-like system (omega Centauri) in the Galactic halo is known to have multiple stellar populations with a significant spread in iron abundance and age. Similar findings in the Galactic bulge have been hampered by the obscuration arising from thick and varying layers of interstellar dust. Here we report that Terzan 5, a globular-cluster-like system in the Galactic bulge, has two stellar populations with different iron contents and ages. Terzan 5 could be the surviving remnant of one of the primordial building blocks that are thought to merge and form galaxy bulges.

  20. Assembly of Robust Bacterial Microcompartment Shells Using Building Blocks from an Organelle of Unknown Function

    SciTech Connect

    Lassila, JK; Bernstein, SL; Kinney, JN; Axen, SD; Kerfeld, CA

    2014-05-29

    Bacterial microconnpartnnents (BMCs) sequester enzymes from the cytoplasmic environment by encapsulation inside a selectively permeable protein shell. Bioinformatic analyses indicate that many bacteria encode BMC clusters of unknown function and with diverse combinations of shell proteins. The genome of the halophilic myxobacterium Haliangium ochraceum encodes one of the most atypical sets of shell proteins in terms of composition and primary structure. We found that microconnpartnnent shells could be purified in high yield when all seven H. ochraceum BMC shell genes were expressed from a synthetic operon in Escherichia coll. These shells differ substantially from previously isolated shell systems in that they are considerably smaller and more homogeneous, with measured diameters of 39 2 nm. The size and nearly uniform geometry allowed the development of a structural model for the shells composed of 260 hexagonal units and 13 hexagons per icosahedral face. We found that new proteins could be recruited to the shells by fusion to a predicted targeting peptide sequence, setting the stage for the use of these remarkably homogeneous shells for applications such as three-dimensional scaffolding and the construction of synthetic BMCs. Our results demonstrate the value of selecting from the diversity of BMC shell building blocks found in genomic sequence data for the construction of novel compartments. (C) 2014 Elsevier Ltd. All rights reserved.

  1. van der Waals Solids from Self-Assembled Nanoscale Building Blocks.

    PubMed

    Choi, Bonnie; Yu, Jaeeun; Paley, Daniel W; Trinh, M Tuan; Paley, Maria V; Karch, Jessica M; Crowther, Andrew C; Lee, Chul-Ho; Lalancette, Roger A; Zhu, Xiaoyang; Kim, Philip; Steigerwald, Michael L; Nuckolls, Colin; Roy, Xavier

    2016-02-10

    Traditional atomic van der Waals materials such as graphene, hexagonal boron-nitride, and transition metal dichalcogenides have received widespread attention due to the wealth of unusual physical and chemical behaviors that arise when charges, spins, and vibrations are confined to a plane. Though not as widespread as their atomic counterparts, molecule-based two-dimensional (2D) layered solids offer significant benefits; their structural flexibility will enable the development of materials with tunable properties. Here we describe a layered van der Waals solid self-assembled from a structure-directing building block and C60 fullerene. The resulting crystalline solid contains a corrugated monolayer of neutral fullerenes and can be mechanically exfoliated. The absorption spectrum of the bulk solid shows an optical gap of 390 ± 40 meV that is consistent with thermal activation energy obtained from electrical transport measurement. We find that the dimensional confinement of fullerenes significantly modulates the optical and electronic properties compared to the bulk solid.

  2. Ultraflat Au nanoplates as a new building block for molecular electronics

    NASA Astrophysics Data System (ADS)

    Jeong, Wooseok; Lee, Miyeon; Lee, Hyunsoo; Lee, Hyoban; Kim, Bongsoo; Park, Jeong Young

    2016-05-01

    We demonstrate the charge transport properties of a self-assembled organic monolayer on Au nanoplates with conductive probe atomic force microscopy (CP-AFM). Atomically flat Au nanoplates, a few hundred micrometers on each side, that have only (111) surfaces, were synthesized using the chemical vapor transport method; these nanoplates were employed as the substrates for hexadecanethiol (HDT) self-assembled monolayers (SAMs). Atomic-scale high-resolution images show (\\sqrt{3}× \\sqrt{3}){{R}}30^\\circ molecular periodicity, indicating a well-ordered structure of the HDT on the Au nanoplates. We observed reduced friction and adhesion forces on the HDT SAMs on Au nanoplates, compared with Si substrates, which is consistent with the lubricating nature of HDT SAMs. The electrical properties, such as I-V characteristics and current as a function of load, were measured using CP-AFM. We obtained a tunneling decay constant (β) of 0.57 Å-1, including through-bond ({β }{tb} = 0.99 Å-1) and through-space ({β }{{ts}} = 1.36 Å-1) decay constants for the two-pathway model. This indicates that the charge transport properties of HDT SAMs on Au nanoplates are consistent with those on a Au (111) film, suggesting that SAMs on nanoplates can provide a new building block for molecular electronics.

  3. Flexible Fabrication of Shape-Controlled Collagen Building Blocks for Self-Assembly of 3D Microtissues.

    PubMed

    Zhang, Xu; Meng, Zhaoxu; Ma, Jingyun; Shi, Yang; Xu, Hui; Lykkemark, Simon; Qin, Jianhua

    2015-08-12

    Creating artificial tissue-like structures that possess the functionality, specificity, and architecture of native tissues remains a big challenge. A new and straightforward strategy for generating shape-controlled collagen building blocks with a well-defined architecture is presented, which can be used for self-assembly of complex 3D microtissues. Collagen blocks with tunable geometries are controllably produced and released via a membrane-templated microdevice. The formation of functional microtissues by embedding tissue-specific cells into collagen blocks with expression of specific proteins is described. The spontaneous self-assembly of cell-laden collagen blocks into organized tissue constructs with predetermined configurations is demonstrated, which are largely driven by the synergistic effects of cell-cell and cell-matrix interactions. This new strategy would open up new avenues for the study of tissue/organ morphogenesis, and tissue engineering applications.

  4. Acetohydroxamic Acid Complexes with Trivalent f-Block Metal Cations

    SciTech Connect

    Sinkov, Serguei I.; Choppin, Gregory

    2003-11-01

    Acetohydroxamic acid has been studied by optical absorbance spectroscopy as a complex forming reagent for the lighter trivalent lanthanides and actinides (Pu(III) and Am(III)) in aqueous solution at 2.0 M (NaClO4) ionic strength. The highest stoichiometry in all the cases studied has been found to be a 1:4 metal-to-ligand ratio; formation of tetrahydroxamato species requires a high excess of the ligand and alkaline pH, Spectrophotometric monitoring confirmed the presence of Pu(III) by electrochemical reduction of Pu(IV) in the course of the pH titration experiment. The formation constants can be used for optimization of processing flowsheets in the advanced PUREX process.

  5. Thermodynamics and phase behavior of acid-tethered block copolymers with ionic liquids.

    PubMed

    Jung, Ha Young; Park, Moon Jeong

    2016-12-21

    We investigate the phase behavior of acid-tethered block copolymers with and without ionic liquids. Two phosphonated block copolymers and their sulfonated analogs were synthesized by fine-tuning the degree of polymerization and the acid content. The block copolymers carrying acid groups with ionic liquids exhibited rich phase sequences, i.e., disorder-lamellae (LAM), gyroid-LAM, gyroid-hexagonal cylinder (HEX), and gyroid-A15 lattice, and the cation/anion ratio in the ionic liquid exerted profound effects on the segregation strength and topology of the self-assembled structures. Additionally, using ionic liquids with excessive cation content was found to enhance the effective Flory-Huggins interaction parameter, χeff, of the samples. However, as the anion content of the ionic liquids increased the segregation strength decreased. This is attributed to the packing frustration accompanied by the prevailing repulsive electrostatic interactions of the anions in the ionic liquid and the polymer matrix. As the hydrophobicity of the ionic liquids increased, well-defined ordered phases emerged in the phosphonated block copolymers with increased anion content, contrary to the disordered phases of the sulfonated samples. Thus, the balance between solvation energy of the anions and the electrostatic interactions is a key determinant of the thermodynamics of acid-tethered block copolymers containing ionic liquids.

  6. The pherophorins: common, versatile building blocks in the evolution of extracellular matrix architecture in Volvocales.

    PubMed

    Hallmann, Armin

    2006-01-01

    Green algae of the order Volvocales provide an unrivalled opportunity for exploring the transition from unicellularity to multicellularity. They range from unicells, like Chlamydomonas, through homocytic colonial forms with increasing cooperation of individual cells, like Gonium or Pandorina, to heterocytic multicellular forms with different cell types and a complete division of labour, like Volvox. A fundamental requirement for the evolution of multicellularity is the development of a complex, multifunctional extracellular matrix (ECM). The ECM has many functions, which can change under developmental control or as a result of environmental factors. Here molecular data from 15 novel proteins are presented. These proteins have been identified in Chlamydomonas reinhardtii, Gonium pectorale, Pandorina morum and Volvox carteri, and all belong to a single protein family, the pherophorins. Pherophorin-V1 is shown to be a glycoprotein localized to the 'cellular zone' of the V. carteri ECM. Pherophorin-V1 and -V2 mRNAs are strongly induced not only by the sex inducer, which triggers sexual development at extremely low concentrations, but also by mechanical wounding. Like the extensins of higher plants, which are also developmentally controlled or sometimes inducible by wounding, the pherophorins contain a (hydroxy-)proline-rich (HR) rod-like domain and are abundant within the extracellular compartment. In contrast to most extensins, pherophorins have additional globular A and B domains on both ends of the HR domains. Therefore pherophorins most closely resemble a particular class of higher plant extensin, the solanaceous lectins (e.g. potato lectin), suggesting multivalent carbohydrate-binding functions are present within the A and B domains and are responsible for cross-linking. Our results suggest that pherophorins are used as the building blocks for the extracellular scaffold throughout the Volvocales, with the characteristic mesh sizes in different ECM structures being

  7. Leveraging "raw materials" as building blocks and bioactive signals in regenerative medicine.

    PubMed

    Renth, Amanda N; Detamore, Michael S

    2012-10-01

    Components found within the extracellular matrix (ECM) have emerged as an essential subset of biomaterials for tissue engineering scaffolds. Collagen, glycosaminoglycans, bioceramics, and ECM-based matrices are the main categories of "raw materials" used in a wide variety of tissue engineering strategies. The advantages of raw materials include their inherent ability to create a microenvironment that contains physical, chemical, and mechanical cues similar to native tissue, which prove unmatched by synthetic biomaterials alone. Moreover, these raw materials provide a head start in the regeneration of tissues by providing building blocks to be bioresorbed and incorporated into the tissue as opposed to being biodegraded into waste products and removed. This article reviews the strategies and applications of employing raw materials as components of tissue engineering constructs. Utilizing raw materials holds the potential to provide both a scaffold and a signal, perhaps even without the addition of exogenous growth factors or cytokines. Raw materials contain endogenous proteins that may also help to improve the translational success of tissue engineering solutions to progress from laboratory bench to clinical therapies. Traditionally, the tissue engineering triad has included cells, signals, and materials. Whether raw materials represent their own new paradigm or are categorized as a bridge between signals and materials, it is clear that they have emerged as a leading strategy in regenerative medicine. The common use of raw materials in commercial products as well as their growing presence in the research community speak to their potential. However, there has heretofore not been a coordinated or organized effort to classify these approaches, and as such we recommend that the use of raw materials be introduced into the collective consciousness of our field as a recognized classification of regenerative medicine strategies.

  8. High-surface Thermally Stable Mesoporous Gallium Phosphates Constituted by Nanoparticles as Primary Building Blocks

    SciTech Connect

    V Parvulescu; V Parvulescu; D Ciuparu; C Hardacre; H Garcia

    2011-12-31

    In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl{sub 3} and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C{sub 16}H{sub 33}(CH{sub 3})3NBr and C{sub 16}PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl{sub 3} and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m{sup 2} g{sup -1}, and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis.

  9. [Fe(bpym)(CN)4]-: a new building block for designing single-chain magnets.

    PubMed

    Toma, Luminita Marilena; Lescouëzec, Rodrigue; Pasan, Jorge; Ruiz-Pérez, Catalina; Vaissermann, Jacqueline; Cano, Joan; Carrasco, Rosa; Wernsdorfer, Wolfgang; Lloret, Francesc; Julve, Miguel

    2006-04-12

    We herein present the preparation, crystal structure, magnetic properties, and theoretical study of new heterobimetallic chains of formula {[Fe(III)(bpym)(CN4)]2M(II)(H2O)2}.6H2O [bpym = 2,2'-bipyrimidine; M = Zn (2), Co (3), Cu (4), and Mn (5)] which are obtained by using the building block PPh4[Fe(bpym)(CN)4].H2O (1) (PPh4+= tetraphenylphosphonium) as a ligand toward the fully solvated MII ions. The structure of complex 1 contains mononuclear [Fe(bpym)(CN)4]- anions. Compounds 2-5 are isostructural 4,2-ribbonlike bimetallic chains where the [Fe(bpym)(CN)4]- unit acts as a bis-monodenate ligand through two of its four cyanide ligands toward the M atom. Water hexamer clusters (4) and regular alternating fused six- and four-membered water rings with two dangling water molecules (2, 3, and 5) are trapped between the cyanide-bridged 4,2-ribbonlike chains. 1 and 2 behave as magnetically isolated low-spin iron(III) centers. 3 behaves as a single-chain magnet (SCM) with intrachain ferromagnetic coupling, slow magnetic relaxation, hysteresis effects, and frequency-dependent ac signals at T < 7 K). As expected for a thermally activated process, the nucleation field (Hn) in 3 increases with decreasing T and increasing v. Below 1.0 K, Hn becomes temperature independent but remains strongly sweep rate dependent. In this temperature range, the reversal of the magnetization may be induced by a quantum nucleation of a domain wall that then propagates due to the applied field. 4 and 5 are ferro- and ferrimagnetic chains respectively, with metamagnetic-like behavior (4). DFT-type calculations and QMC methodology provided a good understanding of the magnetic properties of 3-5.

  10. Leveraging “Raw Materials” as Building Blocks and Bioactive Signals in Regenerative Medicine

    PubMed Central

    Renth, Amanda N.

    2012-01-01

    Components found within the extracellular matrix (ECM) have emerged as an essential subset of biomaterials for tissue engineering scaffolds. Collagen, glycosaminoglycans, bioceramics, and ECM-based matrices are the main categories of “raw materials” used in a wide variety of tissue engineering strategies. The advantages of raw materials include their inherent ability to create a microenvironment that contains physical, chemical, and mechanical cues similar to native tissue, which prove unmatched by synthetic biomaterials alone. Moreover, these raw materials provide a head start in the regeneration of tissues by providing building blocks to be bioresorbed and incorporated into the tissue as opposed to being biodegraded into waste products and removed. This article reviews the strategies and applications of employing raw materials as components of tissue engineering constructs. Utilizing raw materials holds the potential to provide both a scaffold and a signal, perhaps even without the addition of exogenous growth factors or cytokines. Raw materials contain endogenous proteins that may also help to improve the translational success of tissue engineering solutions to progress from laboratory bench to clinical therapies. Traditionally, the tissue engineering triad has included cells, signals, and materials. Whether raw materials represent their own new paradigm or are categorized as a bridge between signals and materials, it is clear that they have emerged as a leading strategy in regenerative medicine. The common use of raw materials in commercial products as well as their growing presence in the research community speak to their potential. However, there has heretofore not been a coordinated or organized effort to classify these approaches, and as such we recommend that the use of raw materials be introduced into the collective consciousness of our field as a recognized classification of regenerative medicine strategies. PMID:22462759

  11. Modelling of Shaded and Unshaded Shallow-Ground Heat Pump System for a Residential Building Block in a Mediterranean Climate

    NASA Astrophysics Data System (ADS)

    Bottarelli, M.; Yousif, C.

    2017-01-01

    Heat pumps may be coupled to shallow-ground geothermal fields and used for the purpose of space heating and cooling of buildings. However, quite often it is not possible to locate the geothermal field in cleared grounds, especially in cities where building density is high and land has a high premium. This leads to the possibility of burying the geothermal field under the basement of new building blocks, before construction of the building. In the present work, the shaded-unshaded arrangement is numerically studied by coupling the software DesignBuilder-EnergyPlus to assess the building’s energy requirement with the software FEFLOW to solve the heat transfer equation in porous media. Assuming a standard residential building block, the coupling between the two software is performed by assigning the thermal energy requirement for air conditioning, as calculated by EnergyPlus, to a flat-panel typology of ground heat exchanger simplified in a 2D FEFLOW’s domain. The results show that it is necessary to opt for a dual-source heat pump (air/geothermal) system to ensure that the ground is not frozen or over-heated at peak times and to improve the overall performance of the system.

  12. A crown-like heterometallic unit as the building block for a 3D In-Ge-S framework.

    PubMed

    Han, Xiaohui; Wang, Zhenqing; Xu, Jin; Liu, Dan; Wang, Cheng

    2015-12-14

    Supertetrahedral clusters are the most common building blocks in constructing Group 13/14/16 microporous metal chalcogenide materials while other types of clusters are yet scarcely explored. Herein, a new crown-like building unit [In3Ge3S16] has been obtained. The units assemble into a 3D framework [C6H14NO]4[In6Ge3S17]·1.5H2O (1) via a dual-connection mode and a SrSi2 (srs)-type topology could be achieved by treating each unit as a tri-connected node.

  13. Use of mixed micelles for presentation of building blocks in a new combinatorial discovery methodology: proof-of-concept studies.

    PubMed

    New, Roger; Bansal, Gurpal S; Bogus, Michael; Zajkowska, Kasia; Rickelt, Steffen; Toth, Istvan

    2013-03-14

    We describe a new method of combinatorial screening in which building blocks, instead of being linked together chemically, are placed on the surface of nanoparticles. Two- or three-dimensional structures form on the surface of these particles through the close approach of different building blocks, with sufficient flexibility to be able to adapt and interact with putative binding sites in biological systems. The particles assemble without the need for formation of chemical bonds, so libraries comprised of many structures can be prepared rapidly, with large quantities of material available for testing. Screening methods can include solid and solution-phase binding assays, or tissue culture models, for example looking for structures which can change the behaviour of cells in a disease-modifying manner.

  14. FT-IR spectra of alginic acid block fractions in three species of brown seaweeds.

    PubMed

    Leal, David; Matsuhiro, Betty; Rossi, Miriam; Caruso, Francesco

    2008-02-04

    Sodium alginates obtained by alkaline extraction of Lessonia flavicans, Desmarestia ligulata and Desmarestia distans (Phaeophyta) from southern Chile were partially hydrolyzed with HCl. Each alginate gave three fractions that were characterized using FT-IR spectroscopy. The fractions soluble in 0.3M HCl presented in the fingerprint region four vibrations at around 960, 911, 890 and 815 cm(-1) that were assigned to heteropolymeric blocks. The fractions soluble at pH 2.85 showed bands at around 948, 888 and 820 cm(-1) attributed to homopolymannuronic acid blocks, the first band is resolved in the second-derivative spectra into two bands at 951 and 936 cm(-1). The fractions insoluble at pH 2.85 presented four bands at around 947, 903, 812 and 781 cm(-1), which were assigned to homopolyguluronic acid blocks. For some samples, the second derivative FT-IR spectra showed new bands indicating the presence of other structures, in low proportions. Structures deduced by FT-IR spectroscopy were corroborated by solution (1)H and (13)C NMR spectroscopy. Two-dimensional spectra were collected to confirm the fine structure of the hetero- and homopolymeric fractions. A geometrically optimized model for the disaccharide alpha-l-gulopyranuronosyl-(1-->4)-alpha-l-gulopyranuronic acid was calculated using density functional theory; good agreement was obtained between its corresponding calculated vibrations and the experimental bands assigned to homopolyguluronic acid blocks.

  15. Design and construction of self-assembling supramolecular protein complexes using artificial and fusion proteins as nanoscale building blocks.

    PubMed

    Kobayashi, Naoya; Arai, Ryoichi

    2017-02-01

    The central goal of nanobiotechnology is to design and construct novel biomaterials of nanometer sizes. In this short review, we describe recent progress of several approaches for designing and creating artificial self-assembling protein complexes and primarily focus on the following biotechnological strategies for using artificial and fusion proteins as nanoscale building blocks: fusion proteins designed for symmetrical self-assembly; three-dimensional domain-swapped oligomers; self-assembling designed coiled-coil peptide modules; metal-directed self-assembling engineered proteins; computationally designed self-assembling de novo proteins; and self-assembling protein nanobuilding blocks (PN-Blocks) using an intermolecularly folded dimeric de novo protein. These state-of-the-art nanobiotechnologies for designing supramolecular protein complexes will facilitate the development of novel functional nanobiomaterials.

  16. The Building Blocks for JWST I and T (Integrations and Test) to Operations - From Simulator to Flight Units

    NASA Technical Reports Server (NTRS)

    Fatig, Curtis; Ochs, William; Johns, Alan; Seaton, Bonita; Adams, Cynthia; Wasiak, Francis; Jones, Ronald; Jackson, Wallace

    2012-01-01

    The James Webb Space Telescope (JWST) Project has an extended integration and test (I&T) phase due to long procurement and development times of various components as well as recent launch delays. The JWST Ground Segment and Operations group has developed a roadmap of the various ground and flight elements and their use in the various JWST I&T test programs. The JWST Project s building block approach to the eventual operational systems, while not new, is complex and challenging; a large-scale mission like JWST involves international partners, many vendors across the United States, and competing needs for the same systems. One of the challenges is resource balancing so simulators and flight products for various elements congeal into integrated systems used for I&T and flight operations activities. This building block approach to an incremental buildup provides for early problem identification with simulators and exercises the flight operations systems, products, and interfaces during the JWST I&T test programs. The JWST Project has completed some early I&T with the simulators, engineering models and some components of the operational ground system. The JWST Project is testing the various flight units as they are delivered and will continue to do so for the entire flight and operational system. The JWST Project has already and will continue to reap the value of the building block approach on the road to launch and flight operations.

  17. Symmetric functionalization of polyhedral phenylsilsesquioxanes as a route to nano-building blocks

    NASA Astrophysics Data System (ADS)

    Roll, Mark Francis

    The design and synthesis of nanometer scale structures is of intense current interest. Herein we report on the ability to use symmetric, robust, mutable silsesquioxane ([RSiO3/2]n) nano-building blocks to produce well-defined 3-D structures for electronic or adsorption applications. We are able to show the systematic effects of supermolecular coordination to modulate the density of the molecular packing. This dissertation first describes the synthesis of the elusive decaphenylsilsesquioxane, and the exploration of the substitutionally specific para iodination of the octa-, deca- and dodeca-(p-iodophenyl)-silsesquioxanes, whose single-crystal X-ray diffraction structures are reported. Octa( p-iodophenyl)-silsesquioxane shows supermolecular coordination via Desiraju's halogen-halogen short-contact synthon, forming an open structure with a solvent accessible cavity comprising 40% of the unit cell. The application of palladium, nickel and copper catalyzed cross-coupling techniques using the carbon-iodine bond is explored in order to divergently synthesize crystalline derivatives. These derivatives include the octa(diphenylacetylene)-silsesquioxane and the octa(hexaphenylbenzene)silsesquioxane (56 Aryl), whose single-crystal X-ray diffraction structures are reported. We show that 56 Aryl, which contains more carbon atoms than any other discrete molecule in the Cambridge Structural Database, crystallizes into an extremely open structure with a solvent accessible cavity comprising 55% of the total volume. The supermolecular ordering driven by the bulky hexaphenylbenzene moieties gives nanometer-scale channels along the ab plane. Substitutional specificity is explored in the bromination of octaphenylsilsesquioxane (OPS), and single-crystal X-ray diffraction structures are reported for the octa-, hexadeca- and tetraicosa-brominated derivatives. Precise synthetic control is demonstrated by the unique catalyst-free bromination of OPS, providing the octa

  18. [Fe(III)(dmbpy)(CN)4]-: a new building block for designing single-chain magnets.

    PubMed

    Toma, Luminita Marilena; Pasán, Jorge; Ruiz-Pérez, Catalina; Lloret, Francesc; Julve, Miguel

    2012-11-28

    We herein present the synthesis and magneto-structural study of a new family of heterobimetallic chains of general formula {[Fe(III)(dmbpy)(CN)(4)](2)M(II)(H(2)O)(2)}(n)·pnH(2)O [dmbpy = 4,4'-dimethyl-2,2'-bipyridine; M = Mn (2), Cu (3), Ni (4) and Co (5) with p = 4 (2), 3 (3), 9 (4) and 3.5 (5)] which were prepared by using the mononuclear PPh(4)[Fe(III)(dmbpy)(CN)(4)]·3H(2)O (1) building block (PPh(4)(+) = tetraphenylphosphonium) as a ligand toward fully solvated M(II) ions. The structure of 1 consists of discrete [Fe(III)(dmbpy)(CN)(4)](-) anions, tetraphenylphosphonium cations and noncoordinated water molecules. Complexes 2-5 are isostructural compounds whose structure consists of neutral 4,2-wave like heterobimetallic chains of formula {[Fe(III)(dmbpy)(CN)(4)](2)M(II)(H(2)O)(2)}(n) where the [Fe(III)(dmbpy)(CN)(4)](-) entity adopts a bis-monodentate coordination mode toward trans-[M(II)(H(2)O)(2)] units through two of its four cyanide groups in cis positions. 1 exhibits the magnetic behaviour of magnetically isolated six-coordinate low-spin Fe(III) complexes with an important orbital contribution. 2 behaves as ferrimagnetic Fe(III)(2)Mn(II) chains, whereas 3-5 exhibit intrachain ferromagnetic couplings between the low-spin Fe(III) and either Cu(II) (3), Ni (4) or Co(II) (5) as well as frequency-dependence of the out-of-phase ac susceptibility signals below 3.0 (3), 5.5 (4) and 5.0 K (5). The relaxation time and the energy to reverse the magnetization of 3-5 are related to the anisotropy of the M(II) center and to the intra- and interchain magnetic interactions. Unprecedentedly in the world of cyanide-bearing complexes, 5 exhibits a double slow relaxation of the magnetization.

  19. An Electronic Structure Approach to Charge Transfer and Transport in Molecular Building Blocks for Organic Optoelectronics

    NASA Astrophysics Data System (ADS)

    Hendrickson, Heidi Phillips

    A fundamental understanding of charge separation in organic materials is necessary for the rational design of optoelectronic devices suited for renewable energy applications and requires a combination of theoretical, computational, and experimental methods. Density functional theory (DFT) and time-dependent (TD)DFT are cost effective ab-initio approaches for calculating fundamental properties of large molecular systems, however conventional DFT methods have been known to fail in accurately characterizing frontier orbital gaps and charge transfer states in molecular systems. In this dissertation, these shortcomings are addressed by implementing an optimally-tuned range-separated hybrid (OT-RSH) functional approach within DFT and TDDFT. The first part of this thesis presents the way in which RSH-DFT addresses the shortcomings in conventional DFT. Environmentally-corrected RSH-DFT frontier orbital energies are shown to correspond to thin film measurements for a set of organic semiconducting molecules. Likewise, the improved RSH-TDDFT description of charge transfer excitations is benchmarked using a model ethene dimer and silsesquioxane molecules. In the second part of this thesis, RSH-DFT is applied to chromophore-functionalized silsesquioxanes, which are currently investigated as candidates for building blocks in optoelectronic applications. RSH-DFT provides insight into the nature of absorptive and emissive states in silsesquioxanes. While absorption primarily involves transitions localized on one chromophore, charge transfer between chromophores and between chromophore and silsesquioxane cage have been identified. The RSH-DFT approach, including a protocol accounting for complex environmental effects on charge transfer energies, was tested and validated against experimental measurements. The third part of this thesis addresses quantum transport through nano-scale junctions. The ability to quantify a molecular junction via spectroscopic methods is crucial to their

  20. Heteroscorpionate aluminium complexes as chiral building blocks to engineer helical architectures.

    PubMed

    Castro-Osma, Jose A; Alonso-Moreno, Carlos; Gómez, M Victoria; Márquez-Segovia, Isabel; Otero, Antonio; Lara-Sánchez, Agustín; Fernández-Baeza, Juan; Sánchez-Barba, Luis F; Rodríguez, Ana M

    2013-10-21

    Treatment of heteroscorpionate ligand precursors pbptamH, pbpamH, sbpamH and (S)-mbpamH with 2 equivalents of AlR3 (R = Et, Me) yielded the corresponding binuclear organoaluminium complexes [Al2R4(μ-pbptam)] (R = Me 1, Et 2), [Al2R4(μ-pbpam)] (R = Me 3, Et 4), [Al2R4(μ-sbpam)] (R = Me 5, Et 6) and [Al2R4{μ-(S)-mbpam}] (R = Me 7, Et 8). These complexes have helical chirality due to the demands of the fixed pyrazole rings. The stereoisomerism and the self-assembly processes of these helicates have been studied in some detail in solution by NMR and in the solid state by X-ray diffraction. Mixtures of M- and P-handed enantiomers and mixtures of M- and P-handed diastereoisomers were obtained when achiral (1–4) and chiral (5–8) heteroscorpionate ligands were used as scaffolds, respectively. Re-crystallization from hexane allowed us to obtain M-homochiral architectures in the solid state for the helical complexes [Al2Et4(μ-sbpam)] (6) and [Al2Et4{μ-(S)-mbpam}] (8). The reaction of heteroscorpionate ligands with 3 equivalents of AlR3 (R = Me, Et) led to the corresponding trinuclear organoaluminium complexes [Al3R7(μ3-pbptam)] (R = Me 9, Et 10), [Al3R7(μ3-pbpam)] (R = Me 11, Et 12), [Al3R7(μ3-sbpam)] (R = Me 13, Et 14) and [Al3R7{μ3-(S)-mbpam}] (R = Me 15, Et 16). The extra AlR3 molecule contributes to the formation of a diastereomeric excess of the PS helicate for complexes 15 and 16. X-ray determination of some of the helical complexes allowed us to witness a versatile and efficient self-assembly process of the building blocks (heteroscorpionate aluminium complexes) directed by noncovalent intermolecular CH–π interactions. The structures of these complexes have been determined by spectroscopic methods and the X-ray crystal structures of 2, 6, 8, and 16 have also been established. Concentration-dependent 1H pulsed field-gradient spin echo (PFGSE) NMR experiments provided evidence for the self-assembly of the single molecular species of complex 2 in

  1. Direct block of the cystic fibrosis transmembrane conductance regulator Cl(-) channel by niflumic acid.

    PubMed

    Scott-Ward, T S; Li, H; Schmidt, A; Cai, Z; Sheppard, D N

    2004-01-01

    Niflumic acid is widely used to inhibit Ca(2+) -activated Cl(-) channels. However, the chemical structure of niflumic acid resembles that of diphenylamine-2-carboxylate, a drug that inhibits the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. To investigate how niflumic acid inhibits CFTR Cl(-) channel, we studied recombinant wild-type human CFTR in excised inside-out membrane patches. When added to the intracellular solution, niflumic acid caused a concentration- and voltage-dependent decrease of CFTR Cl(-) current with half-maximal inhibitory concentration (K(i)) of 253 microM and Hill co-efficient of approximately 1, at -50 mV. Niflumic acid inhibition of single CFTR Cl(-) channels was characterized by a very fast, flickery block that decreased dramatically current amplitude without altering open-probability. Consistent with these data, spectral analysis of CFTR Cl(-) currents suggested that channel block by niflumic acid was described by the closed <--> open <--> blocked kinetic scheme with blocker on rate (k(on)) = 13.9 x 10(6) M(-1)s(-1), off rate (k(off))=3348 s(-1) and dissociation constant (K(d)) = 241 microM, at -50 mV. Based on these data, we tested the effects of niflumic acid on transepithelial Cl(-) secretion and cyst growth using type I MDCK epithelial cells. Niflumic acid (200 microM) inhibited cAMP-stimulated, bumetanide-sensitive short-circuit current by 55%. Moreover, the drug potently retarded cyst growth. We conclude that niflumic acid is an open-channel blocker of CFTR that inhibits Cl(-) permeation by plugging the channel pore. It or related agents might be of value in the development of new therapies for autosomal dominant polycystic kidney disease.

  2. Exciton-blocking phosphonic acid-treated anode buffer layers for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Zimmerman, Jeramy D.; Song, Byeongseop; Griffith, Olga; Forrest, Stephen R.

    2013-12-01

    We demonstrate significant improvements in power conversion efficiency of bilayer organic photovoltaics by replacing the exciton-quenching MoO3 anode buffer layer with an exciton-blocking benzylphosphonic acid (BPA)-treated MoO3 or NiO layer. We show that the phosphonic acid treatment creates buffers that block up to 70% of excitons without sacrificing the hole extraction efficiency. Compared to untreated MoO3 anode buffers, BPA-treated NiO buffers exhibit a ˜ 25% increase in the near-infrared spectral response in diphenylanilo functionalized squaraine (DPSQ)/C60-based bilayer devices, increasing the power conversion efficiency under 1 sun AM1.5G simulated solar illumination from 4.8 ± 0.2% to 5.4 ± 0.3%. The efficiency can be further increased to 5.9 ± 0.3% by incorporating a highly conductive exciton blocking bathophenanthroline (BPhen):C60 cathode buffer. We find similar increases in efficiency in two other small-molecule photovoltaic systems, indicating the generality of the phosphonic acid-treated buffer approach to enhance exciton blocking.

  3. Mutation of L-2,3-diaminopropionic acid synthase genes blocks staphyloferrin B synthesis in Staphylococcus aureus

    PubMed Central

    2011-01-01

    Background Staphylococcus aureus synthesizes two siderophores, staphyloferrin A and staphyloferrin B, that promote iron-restricted growth. Previous work on the biosynthesis of staphyloferrin B has focused on the role of the synthetase enzymes, encoded from within the sbnA-I operon, which build the siderophore from the precursor molecules citrate, alpha-ketoglutarate and L-2,3-diaminopropionic acid. However, no information yet exists on several other enzymes, expressed from the biosynthetic cluster, that are thought to be involved in the synthesis of the precursors (or synthetase substrates) themselves. Results Using mutants carrying insertions in sbnA and sbnB, we show that these two genes are essential for the synthesis of staphyloferrin B, and that supplementation of the growth medium with L-2,3-diaminopropionic acid can bypass the block in staphyloferrin B synthesis displayed by the mutants. Several mechanisms are proposed for how the enzymes SbnA, with similarity to cysteine synthase enzymes, and SbnB, with similarity to amino acid dehydrogenases and ornithine cyclodeaminases, function together in the synthesis of this unusual nonproteinogenic amino acid L-2,3-diaminopropionic acid. Conclusions Mutation of either sbnA or sbnB result in abrogation of synthesis of staphyloferrin B, a siderophore that contributes to iron-restricted growth of S. aureus. The loss of staphyloferrin B synthesis is due to an inability to synthesize the unusual amino acid L-2,3-diaminopropionic acid which is an important, iron-liganding component of the siderophore structure. It is proposed that SbnA and SbnB function together as an L-Dap synthase in the S. aureus cell. PMID:21906287

  4. Controls and rates of acid production in commercial-scale sulfur blocks.

    PubMed

    Birkham, T K; Hendry, M J; Barbour, S L; Lawrence, J R

    2010-01-01

    Acidic drainage (pH 0.4-1.0) from oxidizing elemental sulfur (S(0)) blocks is an environmental concern in regions where S(0) is stockpiled. In this study, the locations, controls, and rates of H(2)SO(4) production in commercial-scale S(0) blocks ( approximately 1-2 x 10(6) m(3)) in northern Alberta, Canada, were estimated. In situ modeling of O(2) concentrations ([O(2)]) suggest that 70 to >97% of the annual H(2)SO(4) production occurs in the upper 1 m of the blocks where temperatures increase to >15 degrees C during the summer. Laboratory experiments show that S(0) oxidation rates are sensitive to temperature (Q(10) = 4.3) and dependent on the activity of autotrophic S(0)-oxidizing microbes. The annual efflux of SO(4) in drainage water from a S(0) block (5.5 x 10(5) kg) was within the estimated range of SO(4) production within the block (2.7 x 10(5) to 1.2 x 10(6) kg), suggesting that H(2)SO(4) production and removal rates were approximately equal during the study period. The low mean relative humidity within the block (68%; SD = 17%; n = 21) was attributed to osmotic suction from elevated H(2)SO(4) concentrations and suggests a mean in situ pH of approximately -2.1. The low pH of drainage waters was attributed to the mixing of fresh infiltrating water and low-pH in situ water. Heat generation during S(0) oxidation was an important factor in maintaining elevated temperatures (mean, 11.1 degrees C) within the block. The implications of this research are relevant globally because construction methods and the physical properties of S(0) blocks are similar worldwide.

  5. SYNTHESIS AND CHARACTERIZATION OF SUBSTITUTED POLY(STYRENE)-b-POLY(ACRYLIC ACID) BLOCK COPOLYMER MICELLES

    SciTech Connect

    Pickel, Deanna L; Pickel, Joseph M; Devenyi, Jozsef; Britt, Phillip F

    2009-01-01

    Block copolymer micelle synthesis and characterization has been extensively studied. In particular, most studies have focused on the properties of the hydrophilic corona due to the micelle corona structure s impact on the biodistribution and biocompatibility. Unfortunately, less attention has been given to the effect of the core block on the micelle stability, morphology, and the rate of diffusion of small molecules from the core. This investigation is focused on the synthesis of block copolymers composed of meta-substituted styrenes and acrylic acid by Atom Transfer Radical Polymerization. Micelles with cores composed of substituted styrenes having Tgs ranging from -30 to 100 oC have been prepared and the size and shape of these micelles were characterized by Static and Dynamic Light Scattering and TEM. In addition, the critical micelle concentration and rate of diffusion of small molecules from the core were determined by fluorimetry using pyrene as the probe.

  6. Engineering responsive polymer building blocks with host-guest molecular recognition for functional applications.

    PubMed

    Hu, Jinming; Liu, Shiyong

    2014-07-15

    CONSPECTUS: All living organisms and soft matter are intrinsically responsive and adaptive to external stimuli. Inspired by this fact, tremendous effort aiming to emulate subtle responsive features exhibited by nature has spurred the invention of a diverse range of responsive polymeric materials. Conventional stimuli-responsive polymers are constructed via covalent bonds and can undergo reversible or irreversible changes in chemical structures, physicochemical properties, or both in response to a variety of external stimuli. They have been imparted with a variety of emerging applications including drug and gene delivery, optical sensing and imaging, diagnostics and therapies, smart coatings and textiles, and tissue engineering. On the other hand, in comparison with molecular chemistry held by covalent bonds, supramolecular chemistry built on weak and reversible noncovalent interactions has emerged as a powerful and versatile strategy for materials fabrication due to its facile accessibility, extraordinary reversibility and adaptivity, and potent applications in diverse fields. Typically involving more than one type of noncovalent interactions (e.g., hydrogen bonding, metal coordination, hydrophobic association, electrostatic interactions, van der Waals forces, and π-π stacking), host-guest recognition refers to the formation of supramolecular inclusion complexes between two or more entities connected together in a highly controlled and cooperative manner. The inherently reversible and adaptive nature of host-guest molecular recognition chemistry, stemming from multiple noncovalent interactions, has opened up a new platform to construct novel types of stimuli-responsive materials. The introduction of host-guest chemistry not only enriches the realm of responsive materials but also confers them with promising new applications. Most intriguingly, the integration of responsive polymer building blocks with host-guest recognition motifs will endow the former with

  7. Combination of ionic self-assembly and hydrogen bonding as a tool for the synthesis of liquid-crystalline materials and organogelators from a simple building block.

    PubMed

    Camerel, Franck; Faul, Charl F J

    2003-08-07

    In this communication we report on the facile combination of hydrogen bonding and the ionic self-assembly (ISA) process to produce organized materials and fiber-containing organogel superstructures from functionalised oligoelectrolytic building blocks.

  8. Cathepsin D-mediated yolk protein degradation is blocked by acid phosphatase inhibitors.

    PubMed

    Fialho, Eliane; Nakamura, Angelica; Juliano, Luiz; Masuda, Hatisaburo; Silva-Neto, Mário A C

    2005-04-15

    Vitellin (VT) is a lipoglycophosphoprotein stored inside the eggs of every oviparous organism during oogenesis. In the blood-sucking bug Rhodnius prolixus, VT is deposited inside growing oocytes together with two acid hydrolases: acid phosphatase (AP) and cathepsin D (CD). Egg fertilization triggers AP activity and VT proteolysis in vivo [Insect Biochem. Mol. Biol. 2002 (32) 847]. Here, we show that CD is the main protease targeting VT proteolysis during egg development. CD activity in total egg homogenates is blocked by the classical aspartyl protease inhibitor, pepstatin A. Surprisingly, AP inhibitors such as NaF, Na+/K+ tartrate, and inorganic phosphate also block VT proteolysis, whereas this effect is not observed when tyrosine phosphatase inhibitors such as vanadate and phenylarsine oxide or an inhibitor of alkaline phosphatases such as levamisole are used in a VT proteolysis assay. NaF concentrations that block isolated AP activity do not affect the activity of partially purified CD. Therefore, a specific repressor of VT proteolysis must be dephosphorylated by AP in vivo. In conclusion, these results demonstrate for the first time that acid hydrolases act cooperatively to promote yolk degradation during egg development in arthropods.

  9. Amino acid infusion blocks renal tubular uptake of an indium-labelled somatostatin analogue.

    PubMed Central

    Hammond, P. J.; Wade, A. F.; Gwilliam, M. E.; Peters, A. M.; Myers, M. J.; Gilbey, S. G.; Bloom, S. R.; Calam, J.

    1993-01-01

    The Indium-labelled somatostatin analogue pentetreotide has been successfully developed for imaging of somatostatin receptor positive tumours. However there is significant renal tubular uptake of the radiolabelled peptide, which can obscure upper abdominal tumours and would preclude its use for targeted radiotherapy. The aim of this study was to determine whether amino acid infusion, which has been shown to block renal tubular peptide reabsorption, diminishes renal parenchymal uptake of this radiolabelled analogue. Eight patients being scanned with the 111In-labelled somatostatin analogue, pentetreotide, for localisation of gastroenteropancreatic tumours received an infusion of synthetic amino acids. The ratio of isotope uptake in kidney to that in spleen was assessed, and compared to the ratio for matched control patients, to determine if amino acid infusion reduced renal parenchymal uptake of the radiopharmaceutical. The amount of isotope in the urine was determined to ensure that any effect of the amino acid infusion was unrelated to changes in clearance. Infusion of amino acids significantly reduced renal parenchymal uptake of isotope at 4 h. There was a non-significant increase in urinary clearance of isotope over the 4 h, consistent with reduced reuptake and a lack of effect on glomerular filtration rate. This technique, by preventing renal damage, may allow the use of this somatostatin analogue for local radiotherapy, and could be of wider value in blocking tubular re-uptake of potentially nephrotoxic agents, such as radiolabelled Fab fragments. Images Figure 1 PMID:8099808

  10. Electron Transfer within Self-Assembling Cyclic Tetramers Using Chlorophyll-Based Donor-Acceptor Building Blocks

    SciTech Connect

    Gunderson, Victoria L; Smeigh, Amanda L; Kim, Chul Hoon; Co, Dick T; Wasielewski, Michael R

    2012-05-09

    The synthesis and photoinduced charge transfer properties of a series of Chl-based donor-acceptor triad building blocks that self-assemble into cyclic tetramers are reported. Chlorophyll a was converted into zinc methyl 3-ethylpyrochlorophyllide a (Chl) and then further modified at its 20-position to covalently attach a pyromellitimide (PI) acceptor bearing a pyridine ligand and one or two naphthalene-1,8:4,5-bis(dicarboximide) (NDI) secondary electron acceptors to give Chl-PI-NDI and Chl-PI-NDI2. The pyridine ligand within each ambident triad enables intermolecular Chl metal-ligand coordination in dry toluene, which results in the formation of cyclic tetramers in solution, as determined using small- and wide-angle X-ray scattering at a synchrotron source. Femtosecond and nanosecond transient absorption spectroscopy of the monomers in toluene-1% pyridine and the cyclic tetramers in toluene shows that the selective photoexcitation of Chl results in intramolecular electron transfer from 1*Chl to PI to form Chl+.-PI-.-NDI and Chl+.-PI-.-NDI2. This initial charge separation is followed by a rapid charge shift from PI-. to NDI and subsequent charge recombination of Chl+.-PI-NDI-. and Chl+.-PI-(NDI)NDI-. on a 5-30 ns time scale. Charge recombination in the Chl-PI-NDI2 cyclic tetramer (τCR = 30 ± 1 ns in toluene) is slower by a factor of 3 relative to the monomeric building blocks (τCR = 10 ± 1 ns in toluene-1% pyridine). This indicates that the self-assembly of these building blocks into the cyclic tetramers alters their structures in a way that lengthens their charge separation lifetimes, which is an advantageous strategy for artificial photosynthetic systems.

  11. Azaborabutadienes: Synthesis by Metal-Free Carboboration of Nitriles and Utility as Building Blocks for B,N-Heterocycles.

    PubMed

    Kong, Lingbing; Lu, Wei; Li, Yongxin; Ganguly, Rakesh; Kinjo, Rei

    2016-11-14

    Metal-free regioselective carboboration of arylnitriles with L2 PhB: (1: L=oxazol-2-ylidene) catalyzed by Et3 B afforded the unprecedented acyclic 2-aza-4-borabutadienes 2, thus demonstrating a new strategy to construct a B,C,N-mixed π-system involving B=C and C=N bonds. Thermal isomerization of 2 gave C-borylimines (3), and diverse reactivity of 2 a towards several substrates, such as H(+) , F(+) , O2 , S, Se, and isonitriles, allowed construction of boron-containing heterocycles with various ring sizes, thus illustrating the utility of 2 as a synthetic building block.

  12. A versatile building block: the structures and functions of negative-sense single-stranded RNA virus nucleocapsid proteins.

    PubMed

    Sun, Yuna; Guo, Yu; Lou, Zhiyong

    2012-12-01

    Nucleocapsid protein (NPs) of negative-sense single-stranded RNA (-ssRNA) viruses function in different stages of viral replication, transcription, and maturation. Structural investigations show that -ssRNA viruses that encode NPs preliminarily serve as structural building blocks that encapsidate and protect the viral genomic RNA and mediate the interaction between genomic RNA and RNA-dependent RNA polymerase. However, recent structural results have revealed other biological functions of -ssRNA viruses that extend our understanding of the versatile roles of virally encoded NPs.

  13. Deconstructing Building Blocks: Preschoolers' Spatial Assembly Performance Relates to Early Mathematical Skills

    ERIC Educational Resources Information Center

    Verdine, Brian N.; Golinkoff, Roberta M.; Hirsh-Pasek, Kathryn; Newcombe, Nora S.; Filipowicz, Andrew T.; Chang, Alicia

    2014-01-01

    This study focuses on three main goals: First, 3-year-olds' spatial assembly skills are probed using interlocking block constructions (N = 102). A detailed scoring scheme provides insight into early spatial processing and offers information beyond a basic accuracy score. Second, the relation of spatial assembly to early mathematical skills…

  14. Power Block Geometry Applied to the Building of Power Electronics Converters

    ERIC Educational Resources Information Center

    dos Santos, E. C., Jr.; da Silva, E. R. C.

    2013-01-01

    This paper proposes a new methodology, Power Block Geometry (PBG), for the presentation of power electronics topologies that process ac voltage. PBG's strategy uses formal methods based on a geometrical representation with particular rules and defines a universe with axioms and conjectures to establish a formation law. It allows power…

  15. Building block extraction and classification by means of Markov random fields using aerial imagery and LiDAR data

    NASA Astrophysics Data System (ADS)

    Bratsolis, E.; Sigelle, M.; Charou, E.

    2016-10-01

    Building detection has been a prominent area in the area of image classification. Most of the research effort is adapted to the specific application requirements and available datasets. Our dataset includes aerial orthophotos (with spatial resolution 20cm), a DSM generated from LiDAR (with spatial resolution 1m and elevation resolution 20 cm) and DTM (spatial resolution 2m) from an area of Athens, Greece. Our aim is to classify these data by means of Markov Random Fields (MRFs) in a Bayesian framework for building block extraction and perform a comparative analysis with other supervised classification techniques namely Feed Forward Neural Net (FFNN), Cascade-Correlation Neural Network (CCNN), Learning Vector Quantization (LVQ) and Support Vector Machines (SVM). We evaluated the performance of each method using a subset of the test area. We present the classified images, and statistical measures (confusion matrix, kappa coefficient and overall accuracy). Our results demonstrate that the MRFs and FFNN perform better than the other methods.

  16. Protective effects of nonionic tri-block copolymers on bile acid-mediated epithelial barrier disruption.

    SciTech Connect

    Edelstein, A.; Fink, D.; Musch, M.; Valuckaite, V.; Zabornia, O.; Grubjesic, S.; Firestone, M. A.; Matthews, J. B.; Alverdy, J. C.

    2011-11-01

    Translocation of bacteria and other luminal factors from the intestine following surgical injury can be a major driver of critical illness. Bile acids have been shown to play a key role in the loss of intestinal epithelial barrier function during states of host stress. Experiments to study the ability of nonionic block copolymers to abrogate barrier failure in response to bile acid exposure are described. In vitro experiments were performed with the bile salt sodium deoxycholate on Caco-2 enterocyte monolayers using transepithelial electrical resistance to assay barrier function. A bisphenol A coupled triblock polyethylene glycol (PEG), PEG 15-20, was shown to prevent sodium deoxycholate-induced barrier failure. Enzyme-linked immunosorbent assay, lactate dehydrogenase, and caspase 3-based cell death detection assays demonstrated that bile acid-induced apoptosis and necrosis were prevented with PEG 15-20. Immunofluorescence microscopic visualization of the tight junctional protein zonula occludens 1 (ZO-1) demonstrated that PEG 15-20 prevented significant changes in tight junction organization induced by bile acid exposure. Preliminary transepithelial electrical resistance-based studies examining structure-function correlates of polymer protection against bile acid damage were performed with a small library of PEG-based copolymers. Polymer properties associated with optimal protection against bile acid-induced barrier disruption were PEG-based compounds with a molecular weight greater than 10 kd and amphiphilicity. The data demonstrate that PEG-based copolymer architecture is an important determinant that confers protection against bile acid injury of intestinal epithelia.

  17. Deconstructing Building Blocks: Preschoolers' Spatial Assembly Performance Relates to Early Mathematics Skills

    PubMed Central

    Verdine, Brian N.; Golinkoff, Roberta Michnick; Hirsh-Pasek, Kathryn; Newcombe, Nora S.; Filipowicz, Andrew T.; Chang, Alicia

    2013-01-01

    This study focuses on three main goals: First, 3-year-olds' spatial assembly skills are probed using interlocking block constructions (N = 102). A detailed scoring scheme provides insight into early spatial processing and offers information beyond a basic accuracy score. Second, the relation of spatial assembly to early mathematics skills was evaluated. Spatial skill independently predicted a significant amount of the variability in concurrent mathematics performance. Finally, the relationship between spatial assembly skill and socioeconomic status, gender, and parent-reported spatial language was examined. While children's performance did not differ by gender, lower-SES children were already lagging behind higher-SES children in block assembly. Furthermore, lower-SES parents reported using significantly fewer spatial words with their children. PMID:24112041

  18. Cost, Schedule and Risk Management, The Building Blocks of a U.S. Nuclear Project

    SciTech Connect

    Redding, John

    2002-07-01

    The most important consideration in the decision to build a new nuclear plant is the capital cost. Right? Yes and no. Yes, the capital cost accounts for 80% of the generation cost of a new plant. No, because there are other equally important considerations. (author)

  19. Report of the Task Force - Space for Health Sciences. Building Blocks. Volume III.

    ERIC Educational Resources Information Center

    Council of Ontario Universities, Toronto.

    The Task Force on Space for Health Sciences is one of four task forces established by the Committee on Capital Financing of the Council of Ontario Universities to work toward the development of a capital formula that would define space needs and building costs for Ontario universities. Each task force has a particular assignment related to the…

  20. Getting "What Works" Working: Building Blocks for the Integration of Experimental and Improvement Science

    ERIC Educational Resources Information Center

    Peterson, Amelia

    2016-01-01

    As a systemic approach to improving educational practice through research, "What Works" has come under repeated challenge from alternative approaches, most recently that of improvement science. While "What Works" remains a dominant paradigm for centralized knowledge-building efforts, there is need to understand why this…

  1. The DNA of Community-Based Problem Solving: Community Colleges as Building Blocks.

    ERIC Educational Resources Information Center

    Oberst, Gayle F.; Wanke, Jurgen

    1997-01-01

    Summarizes results of the Gulf Coast Community College's Citizen Leadership Institute's 30-hour Citizen Leadership Training Program designed to build leadership skills through the stages of awareness, transformation, commitment, and action. The curriculum cultivates citizens to be community leaders who recognize and accept responsibility for…

  2. Ultrafast excited state dynamics of 5,6-dihydroxyindole, a key eumelanin building block: nonradiative decay mechanism.

    PubMed

    Gauden, Magdalena; Pezzella, Alessandro; Panzella, Lucia; Napolitano, Alessandra; d'Ischia, Marco; Sundström, Villy

    2009-09-17

    As part of a program designed to elucidate the excited state properties of key eumelanin building blocks, we report herein a study of 5,6-dihydroxyindole (DHI) in phosphate buffer at pH 3 and pH 7 using femtosecond transient absorption spectroscopy. The transient absorption changes following excitation at 266 nm were used to directly monitor relaxation of the excited states. It was found that the initially generated excited state of DHI, exhibiting two main absorption bands at approximately 450 and approximately 550 nm, decays with a time constant of 5-10 ps to the equilibrated singlet excited state characterized by a very similar spectrum. This latter state then decays to the ground state and the triplet state with a characteristic time of approximately 140-180 ps. Concomitant with the singlet excited state decay of DHI, spectral features characteristic of the DHI cation radical (band at approximately 575 nm) and the triplet state (band at 440-450 nm) are detected. These species do not decay further since geminate recombination of the solvated electron and the DHI radical cation, as well as deprotonation of the cation to form the neutral semiquinone radical, occur on a time scale longer than that covered by the present experiments. These results offer novel insights into the mechanisms of nonradiative decay of eumelanin building blocks of possible relevance to the putative photoprotective and phototoxic roles of these biopolymers.

  3. Rational design of solid catalysts for the selective use of glycerol as a natural organic building block.

    PubMed

    Jérôme, François; Pouilloux, Yannick; Barrault, Joël

    2008-01-01

    Glycerol is the main co-product of the vegetable oils industry (especially biodiesel). With the rapid development of oleochemistry, the production of glycerol is rapidly increasing and chemists are trying to find new applications of glycerol to encourage a better industrial development of vegetable oils. In this Review, attention is focused on the selective use of glycerol as a safe organic building block for organic chemistry. An overview is given of the different heterogeneous catalytic routes developed by chemists for the successful and environmentally friendly use of glycerol in sustainable organic chemistry. In particular, the effects of different catalyst structural parameters are discussed to clearly highlight how catalysis can help organic chemists to overcome the drawbacks stemming from the use of glycerol as a safe organic building block. It is shown that heterogeneous catalysis offers efficient routes for bypassing the traditional use of highly toxic and expensive epichlorohydrin, 3-chloro-1,2-propanediol, or glycidol, which are usually used as a glyceryl donor in organic chemistry.

  4. Synthesis of histone proteins by CPE ligation using a recombinant peptide as the C-terminal building block.

    PubMed

    Kawakami, Toru; Yoshikawa, Ryo; Fujiyoshi, Yuki; Mishima, Yuichi; Hojo, Hironobu; Tajima, Shoji; Suetake, Isao

    2015-11-01

    The post-translational modification of histones plays an important role in gene expression. We report herein on a method for synthesizing such modified histones by ligating chemically prepared N-terminal peptides and C-terminal recombinant peptide building blocks. Based on their chemical synthesis, core histones can be categorized as two types; histones H2A, H2B and H4 which contain no Cys residues, and histone H3 which contains a Cys residue(s) in the C-terminal region. A combination of native chemical ligation and desulphurization can be simply used to prepare histones without Cys residues. For the synthesis of histone H3, the endogenous Cys residue(s) must be selectively protected, while keeping the N-terminal Cys residue of the C-terminal building block that is introduced for purposes of chemical ligation unprotected. To this end, a phenacyl group was successfully utilized to protect endogenous Cys residue(s), and the recombinant peptide was ligated with a peptide containing a Cys-Pro ester (CPE) sequence as a thioester precursor. Using this approach it was possible to prepare all of the core histones H2A, H2B, H3 and H4 with any modifications. The resulting proteins could then be used to prepare a core histone library of proteins that have been post-translationally modified.

  5. The targeted synthesis of single site vanadyl species on the surface and in the framework of silicate building block materials

    SciTech Connect

    Lee, Ming-Yung; Jiao, Jian; Mayes, Richard T; Hagaman, Edward {Ed} W; Barnes, Craig E.

    2011-01-01

    A new synthetic methodology for the targeted preparation of single site, atomically dispersed vanadyl groups in silicate matrices is described. This methodology requires functionalized silicate building blocks Si{sub 8}O{sub 20}(OSnMe{sub 3}){sub 8} that become linked together through vanadyl ({triple_bond}V-O) groups in the matrix. A sequential addition strategy is illustrated which allows the targeting of specific connectivities for the vanadyl group to the silicate building block matrix (i.e. the number of V-O-Si bonds linking the vanadyl unit). Silicate matrices containing exclusively 3-connected (OV(OSi{sub cube}){sub 3}), 2-connected (OV(OR)(OSi{sub cube}){sub 2}) or 1-connected (OVCl{sub 2}(OSi{sub cube})) vanadyl sites are described and characterized via a wide variety spectroscopic and physical techniques (gravimetric analysis, EXAFS, AA and solid state NMR ({sup 51}V, {sup 29}Si, and {sup 17}O)). We demonstrate how the combination of gravimetric, solid state NMR (SSNMR) and EXAFS data can be used to uniquely define the vanadyl sites in these matrices. Furthermore, the use of {sup 17}O SSNMR (1D and MQMAS) is illustrated as an indirect spectroscopic probe to follow changes in the ligands bound to vanadium atom within the vanadyl groups in these matrices.

  6. The Targeted Synthesis of Single Site Vanadyl Species on the Surface and in the Framework of Silicate Building Block Materials

    SciTech Connect

    M Lee; J Jiao; R Mayes; E Hagaman; C Barnes

    2011-12-31

    A new synthetic methodology for the targeted preparation of single site, atomically dispersed vanadyl groups in silicate matrices is described. This methodology requires functionalized silicate building blocks Si{sub 8}O{sub 20}(OSnMe{sub 3}){sub 8} that become linked together through vanadyl ({triple_bond}V=O) groups in the matrix. A sequential addition strategy is illustrated which allows the targeting of specific connectivities for the vanadyl group to the silicate building block matrix (i.e. the number of V-O-Si bonds linking the vanadyl unit). Silicate matrices containing exclusively 3-connected (OV(OSi{sub cube}){sub 3}), 2-connected (OV(OR)(OSi{sub cube}){sub 2}) or 1-connected (OVCl{sub 2}(OSi{sub cube})) vanadyl sites are described and characterized via a wide variety spectroscopic and physical techniques (gravimetric analysis, EXAFS, AA and solid state NMR ({sup 51}V, {sup 29}Si, and {sup 17}O)). We demonstrate how the combination of gravimetric, solid state NMR (SSNMR) and EXAFS data can be used to uniquely define the vanadyl sites in these matrices. Furthermore, the use of {sup 17}O SSNMR (1D and MQMAS) is illustrated as an indirect spectroscopic probe to follow changes in the ligands bound to vanadium atom within the vanadyl groups in these matrices.

  7. Theoretical modeling of 2D porous matrices with tunable architecture: From cruciform molecular building blocks to enantioselective adsorbents

    NASA Astrophysics Data System (ADS)

    Kasperski, Adam; Rżysko, Wojciech; Szabelski, Paweł

    2016-12-01

    The ability of capturing guest molecules in a selective way is one of desirable properties of modern structured adsorbents. This refers to a wide class of guest molecules, especially to those which are chiral and whose enantiomers are to be efficiently separated. In this contribution, using Monte Carlo modeling, we show how simple molecular building blocks with cruciform shape can be used to create 2D porous matrices with tunable adsorptive properties. To that end we consider different self-assembled structures comprising cross-shaped molecules and probe their ability to retain model guest molecules differing in size and shape. In particular we focus on the adsorption of enantiomeric pairs on these substrates and quantify the associated selectivity. The obtained results show that a suitable choice of the building block, including size and aspect ratio allows for the creation of 2D functional matrices with programmed adsorption performance. The findings of our theoretical investigations can be helpful in designing molecular guest-host systems with potential applications in separations, sensing and heterogeneous catalysis.

  8. Building block diode laser concept for high brightness laser output in the kW range and its applications

    NASA Astrophysics Data System (ADS)

    Ferrario, Fabio; Fritsche, Haro; Grohe, Andreas; Hagen, Thomas; Kern, Holger; Koch, Ralf; Kruschke, Bastian; Reich, Axel; Sanftleben, Dennis; Steger, Ronny; Wallendorf, Till; Gries, Wolfgang

    2016-03-01

    The modular concept of DirectPhotonics laser systems is a big advantage regarding its manufacturability, serviceability as well as reproducibility. By sticking to identical base components an economic production allows to serve as many applications as possible while keeping the product variations minimal. The modular laser design is based on single emitters and various combining technics. In a first step we accept a reduction of the very high brightness of the single emitters by vertical stacking several diodes in fast axis. This can be theoretically done until the combined fast axis beam quality is on a comparable level as the individual diodes slow axis beam quality without loosing overall beam performance after fiber coupling. Those stacked individual emitters can be wavelength stabilized by an external resonator, providing the very same feedback to each of those laser diodes which leads to an output power of about 100 W with BPP of <3.5 mm*mrad (FA) and <5 mm*mrad (SA). In the next steps, further power scaling is accomplished by polarization and wavelength multiplexing yielding high optical efficiencies of more than 80% and resulting in a building block module with about 500 W launched into a 100 μm fiber with 0.15 NA. Higher power levels can be achieved by stacking those building blocks using the very same dense spectral combing technique up to multi kW Systems without further reduction of the BPP. The 500 W building blocks are consequently designed in a way that they feature a high flexibility with regard to their emitting wavelength bandwidth. Therefore, new wavelengths can be implemented by only exchanging parts and without any additional change of the production process. This design principal theoretically offers the option to adapt the wavelength of those blocks to any applications, from UV, visible into the far IR as long as there are any diodes commercially available. This opens numerous additional applications like laser pumping, scientific

  9. Mercaptoacetate blocks fatty acid-induced GLP-1 secretion in male rats by directly antagonizing GPR40 fatty acid receptors.

    PubMed

    Li, Ai-Jun; Wang, Qing; Dinh, Thu T; Simasko, Steve M; Ritter, Sue

    2016-04-15

    Mercaptoacetate (MA) is an orexigenic agent reported to block fatty acid (FA) oxidation. Recently, however, we reported evidence from isolated nodose ganglion neurons that MA antagonizes the G protein-coupled long- and medium-chain FA receptor GPR40. GPR40 mediates FA-induced secretion of the satietogenic incretin peptide glucagon-like peptide 1 (GLP-1), by enteroendocrine L cells, as well as FA-induced enhancement of glucose-stimulated insulin secretion. Our results in cultured nodose neurons suggest that MA would also block GPR40 in enteroendocrine cells controlling GLP-1 secretion. If so, this would suggest an alternative mechanism by which MA increases food intake. We tested the hypothesis that MA blocks FA-induced GLP-1 secretion in vitro using cultured STC-1 cells (a murine enteroendocrine cell line) and in vivo in adult male rats. In vitro, MA blocked the increase in both cytosolic Ca(2+)and GLP-1 release stimulated by FAs and also reduced (but less effectively) the response of STC-1 cells to grifolic acid, a partial agonist of the GPR120 FA receptor. In vivo, MA reduced GLP-1 secretion following olive oil gavage while also increasing glucose and decreasing insulin levels. The carnitine palmatoyltransferase 1 antagonist etomoxir did not alter these responses. Results indicate that MA's actions, including its orexigenic effect, are mediated by GPR40 (and possibly GPR120) receptor antagonism and not by blockade of fat oxidation, as previously believed. Analysis of MA's interaction with GPR40 may facilitate understanding of the multiple functions of this receptor and the manner in which FAs participate in the control of hunger and satiety.

  10. Biocatalytic synthesis of C3 chiral building blocks by chloroperoxidase-catalyzed enantioselective halo-hydroxylation and epoxidation in the presence of ionic liquids.

    PubMed

    Liu, Yan; Wang, Yali; Jiang, Yucheng; Hu, Mancheng; Li, Shuni; Zhai, Quanguo

    2015-01-01

    The optically active C3 synthetic blocks are remarkably versatile intermediates for the synthesis of numerous pharmaceuticals and agrochemicals. This work provides a simple and efficient enzymatic synthetic route for the environment-friendly synthesis of C3 chiral building blocks. Chloroperoxidase (CPO)-catalyzed enantioselective halo-hydroxylation and epoxidation of chloropropene and allyl alcohol was employed to prepare C3 chiral building blocks in this work, including (R)-2,3-dichloro-1-propanol (DCP*), (R)-2,3-epoxy-1-propanol (GLD*), and (R)-3-chloro-1-2-propanediol (CPD*). The ee values of the formed C3 chiral building blocks DCP*, CPD*, and glycidol were 98.1, 97.5, and 96.7%, respectively. Moreover, the use of small amount of imidazolium ionic liquid enhanced the yield efficiently due to the increase of solubility of hydrophobic organic substrates in aqueous reaction media, as well as the improvement of affinity and selectivity of CPO to substrate.

  11. Myricetin blocks lipoteichoic acid-induced COX-2 expression in human gingival fibroblasts.

    PubMed

    Gutiérrez-Venegas, Gloria; Luna, Oscar Alonso; Arreguín-Cano, Juan Antonio; Hernández-Bermúdez, Cristina

    2014-03-01

    Periodontitis is an infectious disease caused by microorganisms present in dental bacterial plaque. Lipoteichoic acid (LTA) is a component of the external membrane of Gram-positive bacteria. It causes septic shock. Ingested flavonoids have been reported to directly affect the regulation of cyclooxygenase-2 (COX-2) expression induced by bacterial toxins. In this study, we examined the effects of four flavonoids (luteolin, fisetin, morin and myricetin) on the activation of ERK1/2, p38 and AKT, and on the synthesis of COX-2 in human gingival fibroblasts treated with LTA from Streptococcus sanguinis. We found that luteolin and myricetin blocked AKT and p38 activation and that myricetin blocked LTA-induced COX-2 expression. The results of our study are important for elucidating the mechanism of action of flavonoid regulation of inflammatory responses.

  12. A tribo-mechanical analysis of PVA-based building-blocks for implementation in a 2-layered skin model.

    PubMed

    Morales Hurtado, M; de Vries, E G; Zeng, X; van der Heide, E

    2016-09-01

    Poly(vinyl) alcohol hydrogel (PVA) is a well-known polymer widely used in the medical field due to its biocompatibility properties and easy manufacturing. In this work, the tribo-mechanical properties of PVA-based blocks are studied to evaluate their suitability as a part of a structure simulating the length scale dependence of human skin. Thus, blocks of pure PVA and PVA mixed with Cellulose (PVA-Cel) were synthesised via freezing/thawing cycles and their mechanical properties were determined by Dynamic Mechanical Analysis (DMA) and creep tests. The dynamic tests addressed to elastic moduli between 38 and 50kPa for the PVA and PVA-Cel, respectively. The fitting of the creep compliance tests in the SLS model confirmed the viscoelastic behaviour of the samples with retardation times of 23 and 16 seconds for the PVA and PVA-Cel, respectively. Micro indentation tests were also achieved and the results indicated elastic moduli in the same range of the dynamic tests. Specifically, values between 45-55 and 56-81kPa were obtained for the PVA and PVA-Cel samples, respectively. The tribological results indicated values of 0.55 at low forces for the PVA decreasing to 0.13 at higher forces. The PVA-Cel blocks showed lower friction even at low forces with values between 0.2 and 0.07. The implementation of these building blocks in the design of a 2-layered skin model (2LSM) is also presented in this work. The 2LSM was stamped with four different textures and their surface properties were evaluated. The hydration of the 2LSM was also evaluated with a corneometer and the results indicated a gradient of hydration comparable to the human skin.

  13. The perils and opportunities of reactive building blocks: Attempted synthesis of new Hg(CN) 2-based coordination polymers and the structures of the resulting products

    NASA Astrophysics Data System (ADS)

    Leznoff, Daniel B.; Katz, Michael J.; Cheng, Leslie K. L.; Draper, Neil D.; Batchelor, Raymond J.

    2006-08-01

    The addition of Hg(CN) 2 to an aqueous solution of CoBr 2 and tris(2-aminoethyl)amine (tren) yields an oxidized peroxocobalt(III)-containing ionic complex {[Co(tren)(CN)] 2(μ-O 2)}[HgBr 4], which has been characterized structurally. The bromide ligands have migrated to the Lewis acidic Hg(CN) 2 moiety with concomitant transfer of the cyanide groups to the cobalt(III) centre. The potentially non-innocent nature of the Hg(CN) 2 building block is also manifested in its reaction with CuCl 2 and N, N-dimethylethylenediamine (dmeda); recrystallization of the initial precipitate from ammonia yielded the oxalate-containing coordination polymer {(dmeda) 2Cu 2(μ-C 2O 4)[Hg(CN) 2Cl] 2Hg(CN) 2}·(H 2O) 1.5. The structure consists of 1D chains of [(dmeda) 2Cu 2(μ-C 2O 4)][Hg(CN) 2Cl] 2 units, which are formed by mercury-bridging chloride ligands as well as N-cyano coordination to the opposing sites of the copper dimer. The chains are connected into a 3D CdSO 4-type array via the second Hg(CN) 2 unit binding to the chlorides; adjacent chains are inclined at 59.0°. The structure can also be considered as a pair of inclined (4,4)-grids fused at [Hg(CN) 2Cl 2] 2- centroids. The oxalate might be generated in situ as a result of the NH 3-triggered release of CN - from Hg(CN) 2, its reaction with available copper(II) to yield cyanogen, and the subsequent hydrolysis of (CN) 2. These two products illustrate examples of potentially undesirable side-reactivities of building blocks that must be considered when rationally designing the synthesis of new coordination polymers.

  14. Energy Efficiency and Conservation Block Grant (EECBG)- Better Buildings Neighborhood Program Final Report

    SciTech Connect

    Brown, Donisha; Harris, Barbara; Blue, Cynthia; Gaskins, Charla

    2014-09-16

    The original BetterBuildings for Greensboro grant program included an outreach campaign to inform 100% of the Greensboro community about the benefits of reducing energy use; a plan to reduce energy consumption in at least 34% of the homes and 10% of the other buildings in the east Greensboro target area; and a plan to create and retain jobs in the energy conservation industry. Under the original program structure the City of Greensboro planned to partner with local and regional lenders to create a diversified portfolio of loan products to meet the needs of various income levels and building types. All participants would participate in the loan programs as a method of meeting the program’s 5 to1 private capital match/leverage requirements. In June 2011 the program was restructured to include partnerships with large commercial and multifamily projects, with these partners providing the greater portion of the required match/leverage. The geographic focus was revised to include reducing energy consumption across the entire City of Greensboro, targeting neighborhoods with high concentrations of low-moderate income households and aged housing stock. The community outreach component used a neighborhood-based approach to train community residents and volunteers to conduct door-to-door neighborhood sweeps; delivered high quality information on available program resources; helped residents to evaluate alternative energy efficiency measures and alternative financing sources; assisted with contractor selections and monitoring/evaluation of work; coordinated activities with BetterBuildings program partners; and collected data required by the Department of Energy. Additionally, HERO (Home Energy Response Officers) delivered intro packages (energy efficiency information and products) to thousands of households at the initial point of contact. A pilot program (Early Adopters) was offered from March 1, 2011 through June 30, 2011. The Early Adopters program was designed to offer

  15. Computer-aided design of nanostructures from self- and directed-assembly of soft matter building blocks

    NASA Astrophysics Data System (ADS)

    Nguyen, Trung Dac

    2011-12-01

    Functional materials that are active at nanometer scales and adaptive to environment have been highly desirable for a huge array of novel applications ranging from photonics, sensing, fuel cells, smart materials to drug delivery and miniature robots. These bio-inspired features imply that the underlying structure of this type of materials should possess a well-defined ordering as well as the ability to reconfigure in response to a given external stimulus such as temperature, electric field, pH or light. In this thesis, we employ computer simulation as a design tool, demonstrating that various ordered and reconfigurable structures can be obtained from the self- and directed-assembly of soft matter nano-building blocks such as nanoparticles, polymer-tethered nanoparticles and colloidal particles. We show that, besides thermodynamic parameters, the self-assembly of these building blocks is governed by nanoparticle geometry, the number and attachment location of tethers, solvent selectivity, balance between attractive and repulsive forces, nanoparticle size polydispersity, and field strength. We demonstrate that higher-order nanostructures, i.e. those for which the correlation length is much greater than the length scale of individual assembling building blocks, can be hierarchically assembled. For instance, bilayer sheets formed by laterally tethered rods fold into spiral scrolls and helical structures, which are able to adopt different morphologies depending on the environmental condition. We find that a square grid structure formed by laterally tethered nanorods can be transformed into a bilayer sheet structure, and vice versa, upon shortening, or lengthening, the rod segments, respectively. From these inspiring results, we propose a general scheme by which shape-shifting particles are employed to induce the reconfiguration of pre-assembled structures. Finally, we investigate the role of an external field in assisting the formation of assembled structures that would

  16. INHIBITION OF FATTY ACID DESATURASES IN Drosophila melanogaster LARVAE BLOCKS FEEDING AND DEVELOPMENTAL PROGRESSION.

    PubMed

    Wang, Yiwen; da Cruz, Tina Correia; Pulfemuller, Alicia; Grégoire, Stéphane; Ferveur, Jean-François; Moussian, Bernard

    2016-05-01

    Fatty acid desaturases are metabolic setscrews. To study their systemic impact on growth in Drosophila melanogaster, we inhibited fatty acid desaturases using the inhibitor CAY10566. As expected, the amount of desaturated lipids is reduced in larvae fed with CAY10566. These animals cease feeding soon after hatching, and their growth is strongly attenuated. A starvation program is not launched, but the expression of distinct metabolic genes is activated, possibly to mobilize storage material. Without attaining the normal size, inhibitor-fed larvae molt to the next stage indicating that the steroid hormone ecdysone triggers molting correctly. Nevertheless, after molting, expression of ecdysone-dependent regulators is not induced. While control larvae molt a second time, these larvae fail to do so and die after few days of straying. These effects are similar to those observed in experiments using larvae deficient for the fatty acid desaturase1 gene. Based on these data, we propose that the ratio of saturated to unsaturated fatty acids adjusts a sensor system that directs feeding behavior. We also hypothesize that loss of fatty acid desaturase activity leads to a block of the genetic program of development progression indirectly by switching on a metabolic compensation program.

  17. Dual Enzyme-Responsive Capsules of Hyaluronic Acid-block-Poly(Lactic Acid) for Sensing Bacterial Enzymes.

    PubMed

    Tücking, Katrin-Stephanie; Grützner, Verena; Unger, Ronald E; Schönherr, Holger

    2015-07-01

    The synthesis of novel amphiphilic hyaluronic acid (HYA) and poly(lactic acid) (PLA) block copolymers is reported as the key element of a strategy to detect the presence of pathogenic bacterial enzymes. In addition to the formation of defined HYA-block-PLA assemblies, the encapsulation of fluorescent reporter dyes and the selective enzymatic degradation of the capsules by hyaluronidase and proteinase K are studied. The synthesis of the dual enzyme-responsive HYA-b-PLA is carried out by copper-catalyzed Huisgen 1,3-dipolar cycloaddition. The resulting copolymers are assembled in water to form vesicular structures, which are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering (DLS), and fluorescence lifetime imaging microscopy (FLIM). DLS measurements show that both enzymes cause a rapid decrease in the hydrodynamic diameter of the nanocapsules. Fluorescence spectroscopy data confirm the liberation of encapsulated dye, which indicates the disintegration of the capsules and validates the concept of enzymatically triggered payload release. Finally, cytotoxicity assays confirm that the HYA-b-PLA nanocapsules are biocompatible with primary human dermal microvascular endothelial cells.

  18. Structural and functional diversity among amyloid proteins: Agents of disease, building blocks of biology, and implications for molecular engineering.

    PubMed

    Bleem, Alissa; Daggett, Valerie

    2017-01-01

    Amyloids have long been associated with protein dysfunction and neurodegenerative diseases, but recent research has demonstrated that some organisms utilize the unique properties of the amyloid fold to create functional structures with important roles in biological processes. Additionally, new engineering approaches have taken advantage of amyloid structures for implementation in a wide variety of materials and devices. In this review, the role of amyloid in human disease is discussed and compared to the functional amyloids, which serve a largely structural purpose. We then consider the use of amyloid constructs in engineering applications, including their utility as building blocks for synthetic biology and molecular engineering. Biotechnol. Bioeng. 2017;114: 7-20. © 2016 Wiley Periodicals, Inc.

  19. Combining a Ru(II) "Building Block" and Rapid Screening Approach to Identify DNA Structure-Selective "Light Switch" Compounds.

    PubMed

    Wachter, Erin; Moyá, Diego; Glazer, Edith C

    2017-02-13

    A chemically reactive Ru(II) "building block", able to undergo condensation reactions with substituted diamines, was utilized to create a small library of luminescent "light switch" dipyrido-[3,2-a:2',3'-c] phenazine (dppz) complexes. The impact of substituent identity, position, and the number of substituents on the light switch effect was investigated. An unbiased, parallel screening approach was used to evaluate the selectivity of the compounds for a variety of different biomolecules, including protein, nucleosides, single stranded DNA, duplex DNA, triplex DNA, and G-quadruplex DNA. Combining these two approaches allowed for the identification of hit molecules that showed different selectivities for biologically relevant DNA structures, particularly triplex and quadruplex DNA.

  20. Uncovering the structure of human red hair pheomelanin: benzothiazolylthiazinodihydroisoquinolines as key building blocks.

    PubMed

    Greco, Giorgia; Panzella, Lucia; Verotta, Luisella; d'Ischia, Marco; Napolitano, Alessandra

    2011-04-25

    Biomimetic oxidation of the pheomelanin precursor 5-S-cysteinyldopa in the presence of Zn(2+) ions led to the isolation of two isomeric products, one of which could be identified as the benzothiazolylthiazinodihydroisoquinoline 5, while the other proved too unstable for a complete characterization. Both these products were converted into more stable oxidized forms, which after ethylchloroformate derivatization were characterized as the ethyl ester/ethoxycarbonyl isoquinolines 8 and 9. Compound 5 exhibited absorption characteristics similar to those of red hair pheomelanin, including a main band around 400 nm in acids. Similarly to red hair pheomelanin and synthetic pigments, 5 afforded on chemical degradation a thiazolylpyridinecarboxylic acid fragment. Model chemical studies allowed the proposal of a formation mechanism for the benzothiazole and dihydroisoquinoline systems in compound 5.

  1. Polymerization of Building Blocks of Life on Europa and Other Icy Moons.

    PubMed

    Kimura, Jun; Kitadai, Norio

    2015-06-01

    The outer Solar System may provide a potential habitat for extraterrestrial life. Remote sensing data from the Galileo spacecraft suggest that the jovian icy moons--Europa, Ganymede, and possibly Callisto--may harbor liquid water oceans underneath their icy crusts. Although compositional information required for the discussion of habitability is limited because of significantly restricted observation data, organic molecules are ubiquitous in the Universe. Recently, in situ spacecraft measurements and experiments suggest that amino acids can be formed abiotically on interstellar ices and comets. These amino acids could be continuously delivered by meteorite or comet impacts to icy moons. Here, we show that polymerization of organic monomers, in particular amino acids and nucleotides, could proceed spontaneously in the cold environment of icy moons, in particular the jovian icy moon Europa as a typical example, based on thermodynamic calculations, though kinetics of formation are not addressed. Observed surface temperature on Europa is 120 and 80 K in the equatorial region and polar region, respectively. At such low temperatures, Gibbs energies of polymerization become negative, and the estimated thermal structure of the icy crust should contain a shallow region (i.e., at a depth of only a few kilometers) favorable for polymerization. Investigation of the possibility of organic monomer polymerization on icy moons could provide good constraints on the origin and early evolution of extraterrestrial life.

  2. The Hydrolysis of Diclofenac Esters: Synthetic Prodrug Building Blocks for Biodegradable Drug-Polymer Conjugates.

    PubMed

    Wang, Feng; Finnin, Joshua; Tait, Cassandra; Quirk, Stephen; Chekhtman, Igor; Donohue, Andrew C; Ng, Sarah; D'Souza, Asha; Tait, Russell; Prankerd, Richard

    2016-02-01

    Degradation reactions on diclofenac-monoglycerides (3a,b), diclofenac-(p-hydroxybenzoate)-2-monoglyceride (3c), diclofenac (1), and diclofenac lactam (4) were performed at 37 °C in isotonic buffer solutions (apparent pH range 1-8) containing varying concentrations of acetonitrile (ACN). The concentration remaining of each analyte was measured versus time. Diclofenac-monoglycerides and diclofenac-(p-hydroxybenzoate)-2-monoglyceride (3c) were both found to undergo facile and complete hydrolysis in pH 7.4 isotonic phosphate buffer/10% ACN. Under mildly acidic, neutral or alkaline conditions, diclofenac-(p-hydroxybenzoate)-2-monoglyceride (3c) had the fastest hydrolysis rate (t1/2 = 3.23 h at pH 7.4), with simultaneous formation of diclofenac lactam (4) and diclofenac (1). Diclofenac-monoglycerides (3a,b) hydrolyzed more slowly under the same conditions, to again yield both diclofenac (1) and diclofenac lactam (4). There was also transesterification of diclofenac-2-monoglyceride (3b) to its regioisomer, diclofenac-1-monoglyceride (3a) across the pH range. Diclofenac was shown to be stable in neutral or alkaline conditions but cyclized to form the lactam (4) in acidic conditions. Conversely, the lactam (4) was stable under acidic conditions but was converted to an unknown species under alkaline or neutral conditions.

  3. Polymerization of Building Blocks of Life on Europa and Other Icy Moons

    PubMed Central

    Kitadai, Norio

    2015-01-01

    Abstract The outer Solar System may provide a potential habitat for extraterrestrial life. Remote sensing data from the Galileo spacecraft suggest that the jovian icy moons—Europa, Ganymede, and possibly Callisto—may harbor liquid water oceans underneath their icy crusts. Although compositional information required for the discussion of habitability is limited because of significantly restricted observation data, organic molecules are ubiquitous in the Universe. Recently, in situ spacecraft measurements and experiments suggest that amino acids can be formed abiotically on interstellar ices and comets. These amino acids could be continuously delivered by meteorite or comet impacts to icy moons. Here, we show that polymerization of organic monomers, in particular amino acids and nucleotides, could proceed spontaneously in the cold environment of icy moons, in particular the jovian icy moon Europa as a typical example, based on thermodynamic calculations, though kinetics of formation are not addressed. Observed surface temperature on Europa is 120 and 80 K in the equatorial region and polar region, respectively. At such low temperatures, Gibbs energies of polymerization become negative, and the estimated thermal structure of the icy crust should contain a shallow region (i.e., at a depth of only a few kilometers) favorable for polymerization. Investigation of the possibility of organic monomer polymerization on icy moons could provide good constraints on the origin and early evolution of extraterrestrial life. Key Words: Planetary science—Europa—Planetary habitability and biosignatures—Extraterrestrial life—Extraterrestrial organic compounds. Astrobiology 15, 430–441. PMID:26060981

  4. Model aggregation: a building-block approach to creating large macromolecular regulatory networks

    PubMed Central

    Randhawa, Ranjit; Shaffer, Clifford A.; Tyson, John J.

    2009-01-01

    Motivation: Models of regulatory networks become more difficult to construct and understand as they grow in size and complexity. Modelers naturally build large models from smaller components that each represent subsets of reactions within the larger network. To assist modelers in this process, we present model aggregation, which defines models in terms of components that are designed for the purpose of being combined. Results: We have implemented a model editor that incorporates model aggregation, and we suggest supporting extensions to the Systems Biology Markup Language (SBML) Level 3. We illustrate aggregation with a model of the eukaryotic cell cycle ‘engine’ created from smaller pieces. Availability: Java implementations are available in the JigCell Aggregation Connector. See http://jigcell.biol.vt.edu. Contact: shaffer@vt.edu PMID:19880372

  5. Multi-component superstructures self-assembled from nanocrystal building blocks

    NASA Astrophysics Data System (ADS)

    Tan, Rui; Zhu, Hua; Cao, Can; Chen, Ou

    2016-05-01

    More than three decades of intensive study to make high-quality nanocrystals have created a unique toolbox for building multi-component superstructures, which have been recognized as a new generation of metamaterials important to both fundamental sciences and applied technologies. This minireview summarizes recent advances in this exciting field. We will focus our discussion on the synthetic strategies and superstructures of this multi-component metamaterial, and highlight their novel properties and potential applications. Additionally, some perspectives on possible developments in this field are offered at the end of this review. We hope that this minireview will both inform and stimulate research interests for the design and fabrication of these nanocrystal-based multi-component metamaterials for diverse applications in the future.

  6. Microring resonator-based diamond optothermal switch: a building block for a quantum computing network

    NASA Astrophysics Data System (ADS)

    Huang, Zhihong; Faraon, Andrei; Santori, Charles; Acosta, Victor; Beausoleil, Raymond G.

    2013-03-01

    The negatively-charged nitrogen-vacancy centers in diamond has motivated many groups building scalable quantum information processors based on diamond photonics. This is owning to the long-lived electronic spin coherence and the capability for spin manipulation and readout of NV centers.1-4 The primitive operation is to create entanglement between two NV centers, based on schemes such as 'atom-photon entanglement' proposed by Cabrillo et al.5To scale this type of scheme beyond two qubits, one important component is an optical switch that allows light emitted from a particular device to be routed to multiple locations. With such a switch, one has choices of routing photons to specified paths and has the benefit of improving the entanglement speed by entangling multiple qubits at the same time. Yield of the existing diamond cavities coupled with NV centers are inevitably low, due to the nature of randomness for NV placement and orientation, variation of spectral stability, and variation of cavity resonance frequency and quality factor. An optical switch provides the capability to tolerate a large fraction of defective devices by routing only to the working devices. Many type of switching devices were built on conventional semiconductor materials with mechanisms from mechanical, thermal switching to carrier injection, photonics crystal, and polymer refractive index tuning .6-8 In this paper, we build an optical-thermal switch on diamond with micro-ring waveguides, mainly for the simplicity of the diamond fabrication. The the switching function was realized by locally tuning the temperature of the diamond waveguides. Switching efficiency of 31% at 'drop' port and 73% at 'through' port were obtained.

  7. Synthesis of a versatile building block combining cyclen-derivative DO3A with a polyamine via a rigid spacer.

    PubMed

    Drahoš, Bohuslav; Trávníček, Zdeněk

    2013-11-12

    The five-step synthesis of a polydentate building block combining a cyclen-based macrocycle (DO3A) with N-(2-aminoethyl)propane-1,3-diamine, which are linked through the xylylen moiety as a rigid C-spacer is described. These two molecular parts were coupled by subsequent bromine atom substitution in 1,4-bis(bromomethyl)benzene. First, N-(2-aminoethyl)propane-1,3-diamine was protected by phthaloyl moieties and then it was reacted with 1,4-bis(bromomethyl)benzene to form (2-phthalimidoethyl)(3-phthalimido-prop-1-yl)(4-bromomethylbenzyl)amine (2). This compound underwent a substitution reaction with DO3A in the form of its tert-butyl esters leading to the intermediate 1-{4-[(2-phthalimidoethyl)(3-phthalimidoprop-1-yl)aminomethyl]phenylmethyl}-4,7,10-tris(t-butoxy-carbonylmethyl)-1,4,7,10-tetraazacyclododecane (3). The phthaloyl as well as the t-butyl protecting groups were removed in the next two reaction steps to form the final product 1-{4-[(2-aminoethyl)(3-aminoprop-1-yl)aminomethyl]phenylmethyl}-4,7,10-tris(carboxy-methyl)-1,4,7,10-tetraazacyclododecane (5). The intermediates 1-4 as well as the final product 5 were characterized by elemental analysis, mass spectrometry, and multinuclear (1H and 13C) and two-dimensional NMR spectroscopy. The final product 5 could serve as a potential building block in subsequent syntheses of binuclear complexes of lanthanides and/or transition metals.

  8. DETECTIONS OF FAINT Ly{alpha} EMITTERS AT z = 5.7: GALAXY BUILDING BLOCKS AND ENGINES OF REIONIZATION

    SciTech Connect

    Dressler, Alan; McCarthy, Patrick; Martin, Crystal L.; Henry, Alaina; Sawicki, Marcin E-mail: sawicki@ap.smu.ca

    2011-10-20

    We report results of an unprecedentedly deep, blind search for Ly{alpha} emitters (LAEs) at z = 5.7 using the Inamori-Magellan Areal Camera and Spectrograph (IMACS), with the goal of identifying missing sources of reionization that could also be basic building blocks for today's L* galaxies. We describe how improvements in wide field imaging with the Baade telescope, upgrades to IMACS, and the accumulation of {approx}20 hr of integration per field in excellent seeing led to the detection of single-emission-line sources as faint as F {approx} 2 x 10{sup -18} erg s{sup -1} cm{sup -2}, a sensitivity five times deeper than our first search. A reasonable correction for foreground interlopers implies a steep rise of approximately an order of magnitude in source density for a factor of four drop in flux, from F = 10{sup -17.0} erg s{sup -1} cm{sup -2} to F = 10{sup -17.6} (2.5 x 10{sup -18}) erg s{sup -1} cm{sup -2}. At this flux the putative LAEs have reached a surface density of {approx}1 arcmin{sup -2}-a comoving volume density of 4 x 10{sup -3} Mpc{sup -3}, several times the density of L* galaxies today. Such a population of faint LAEs would account for a significant fraction of the critical flux density required to complete reionization at this epoch, and would be good candidates for building blocks of stellar mass {approx}10{sup 8}-10{sup 9} M{sub sun} for the young galaxies of this epoch.

  9. Building non-tortuous ion-conduction pathways using self-assembled block copolymers

    NASA Astrophysics Data System (ADS)

    Kim, Onnuri; Park, Moon Jeong

    Ion-containing polymers with self-assembled morphologies are becoming important ingredients of a wide range of electrochemical devices such as lithium-ion batteries, fuel cells and electroactive actuators. Although several studies have reported the relationship between morphologies and ion transport properties of such polymers, the most of quantitative analysis have been limited to two-dimensional morphologies as they occupy a large window of the phase diagrams. In present study, we investigated the effects of morphology on the ion transport efficiency with a focus on three-dimensional symmetry. A range of three-dimensional self-assembled morphologies, i.e., ill-defined cubic, orthorhombic network (O70) , and face-centered cubic phases (fcc) were achieved for a single sulfonated block copolymer upon the addition of non-stoichiometric ionic liquids. The type of three-dimensional lattice was found out to play a crucial role in determining the ion transport properties of composite membranes, where the most efficient ion-conduction was demonstrated for fcc phases with lowest tortuosity of 1 over orthorhombic networks phases (tortuosity:1.5). This intriguing result suggests a new avenue to designing polymer electrolytes with improved transport properties.

  10. Multigram-scale synthesis of an orthogonally protected 2-acetamido-4-amino-2,4,6-trideoxy-D-galactose (AAT) building block.

    PubMed

    Christina, A E; Blas Ferrando, V M; de Bordes, F; Spruit, W A; Overkleeft, H S; Codée, J D C; van der Marel, G A

    2012-07-15

    Reported is the gram-scale synthesis of tert-butyldiphenylsilyl 4-(N-benzyloxycarbonyl)-amino-2-azido-2,4,6-trideoxy-β-D-galactopyranoside, which represents an orthogonally protected 2,4-diamino-D-fucose building block, a common constituent of various zwitterionic polysaccharides. The building block has been synthesized from D-glucosamine in 19% overall yield over 14 steps, requiring 5 chromatographic purifications. The key step in the synthesis is the introduction of the C-4 amino substituent, which has been accomplished by a one-pot three step procedure, involving regioselective C-3-O-trichloroacetimidate formation, C-4-O-triflation, and intramolecular substitution. The building block can be used as an acceptor and is readily transformed into a donor glycoside.

  11. Enzymatic hydrolysis studies of arabinogalactan-protein structure from Acacia gum: the self-similarity hypothesis of assembly from a common building block.

    PubMed

    Renard, D; Lavenant-Gourgeon, L; Lapp, A; Nigen, M; Sanchez, C

    2014-11-04

    particles differing in dimensions. The secondary structures content of control and enzyme-treated AGPs were similar, highlighting both the high rigidity of the protein backbone and the overall symmetry of AGP. This conclusion was reinforced by the more compact structures found when AGP was intact compare to the more elongated structures found when AGP was enzymatically cleaved. Finally, the structural similarities found in enzyme-treated AGP together with the theoretical calculations to analytically probe the type of branching would suggest that AGP would be made of a self-similar assembly of two types of building blocks, the second being a five-fold repetition of the first one, for which palindromic amino acid sequence would ensure a self-ordering of carbohydrate moieties along the polypeptide chains. The cleavage would therefore lead to hydrolysed building blocks with similar secondary structures and conformations whatever the enzyme used.

  12. Preparation of fluoride substituted apatite cements as the building blocks for tooth enamel restoration

    NASA Astrophysics Data System (ADS)

    Wei, Jie; Wang, Jiecheng; Liu, Xiaochen; Ma, Jian; Liu, Changsheng; Fang, Jing; Wei, Shicheng

    2011-06-01

    Fluoride substituted apatite cement (fs-AC) was synthesized by using the cement powders of tetracalcium phosphate (TTCP) and sodium fluoride (NaF), and the cement powders were mixed with diluted phosphoric acid (H 3PO 4) as cement liquid to form fs-AC paste. The fs-AC paste could be directly filled into the carious cavities to repair damaged dental enamel. The results indicated that the fs-AC paste was changed into fluorapatite crystals with the atom molar ratio for calcium to phosphorus of 1.66 and the F ion amount of 3 wt% after self-hardening for 2 days. The solubility of fs-AC in Tris-HCl solution (pH 6) was slightly lower than hydroxyapatite cement (HAC) that was similar to the apatite in enamel, indicating the fs-AC was much insensitive to the weakly acidic solution than the apatite in enamel. The fs-AC was tightly combined with the enamel surface because of the chemical reaction between the fs-AC and the apatite in enamel after the caries cavities was filled with fs-AC. The extracts of fs-AC caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. The fs-AC had potential prospect for the reconstitution of carious lesion of dental enamel.

  13. Nanoscale building blocks in a novel lithium arsenotungsten bronze: Synthesis and characterization

    SciTech Connect

    Zhao, Pei; Mangir Murshed, M.; Huq, Ashfia; Grossmann, Henrike K.; Mädler, Lutz; Alekseev, Evgeny V.; Gesing, Thorsten M.

    2015-03-15

    We report on a novel compound Li{sub 3}AsW{sub 7}O{sub 25} obtained by solid-state reaction and characterized by diffraction and spectroscopic methods. The bronze-type compound crystallizes in the orthorhombic space group Pbca with a=724.38(3) pm, b=1008.15(4) pm, c=4906.16(17) pm and Z=8. The structure is built up by chains of WO{sub 6} octahedra interconnected by AsO{sub 4} tetrahedra and WO{sub 6} octahedra forming a polyhedral arrangement as seen in intergrowth tungsten bronzes. The X-ray single crystal structure refinement allows solving the complex arsenotungstate framework. The powder neutron diffraction data analysis locates the lithium atoms. Thermal analysis showed that Li{sub 3}AsW{sub 7}O{sub 25} is stable up to its melting at 1135(3) K followed by a decomposition at 1182(5) K. The Kubelka–Munk treatment of the UV–vis spectrum revealed a wide band gap in the range of 2.84–3.40 eV depending on the presumed electron transition type. - Graphical abstract: Crystal structure of Li{sub 3}AsW{sub 7}O{sub 25} showing different schematic components. - Highlights: • A report on a novel compound Li{sub 3}AsW{sub 7}O{sub 25} obtained by solid-state reaction. • Chains and nano-blocks of WO{sub 6} octahedra and AsO{sub 4} tetrahedra formed a structure like intergrowth tungsten bronzes. • X-ray diffraction allowed solving the complex arsenotungstate framework. • Powder neutron diffraction data analysis locates the lithium atoms. • UV–vis spectrum revealed the band-gap.

  14. Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Mahadevan, L.; Driks, Adam; Sahin, Ozgur

    2014-02-01

    Materials that respond mechanically to external chemical stimuli have applications in biomedical devices, adaptive architectural systems, robotics and energy harvesting. Inspired by biological systems, stimuli-responsive materials have been created that can oscillate, transport fluid, provide homeostasis and undergo complex changes in shape. However, the effectiveness of synthetic stimuli-responsive materials in generating work is limited when compared with mechanical actuators. Here, we show that the mechanical response of Bacillus spores to water gradients exhibits an energy density of more than 10 MJ m-3, which is two orders of magnitude higher than synthetic water-responsive materials. We also identified mutations that can approximately double the energy density of the spores and found that they can self-assemble into dense, submicrometre-thick monolayers on substrates such as silicon microcantilevers and elastomer sheets, creating bio-hybrid hygromorph actuators. To illustrate the potential applications of the spores, we used them to build an energy-harvesting device that can remotely generate electrical power from an evaporating body of water.

  15. 5, 10-linked naphthodithiophenes as the building block for semiconducting polymers

    PubMed Central

    Osaka, Itaru; Komatsu, Koki; Koganezawa, Tomoyuki; Takimiya, Kazuo

    2014-01-01

    We present new semiconducting polymers incorporating naphtho[1, 2-b:5, 6-b′] dithiophene (NDT3) and naphtho[2, 1-b:6, 5-b′] dithiophene (NDT4), which are linked at the naphthalene positions, in the polymer backbone. It is interesting that the trend in the ordering structure and thus charge transport properties are quite different from what were observed in the isomeric polymers where the NDT3 and NDT4 cores are linked at the thiophene α-positions. In the thiophene-linked NDT system, the NDT3-based polymer (PNDT3BT) gave the better ordering in thin films and thus the high charge carrier mobility compared to the NDT4-based polymer (PNDT4BT). In the meantime, in the naphthalene-linked NDT system, the NDT4-based polymer (PNDT4iBT) provided the superior properties. Considering that PNDT4iBT has relatively low highest occupied molecular orbital (HOMO) energy level (−5.2 eV) and moderately high mobilities in the order of 10−2 cm2 V−1 s−1, the NDT4 core, when linked at the naphthalene positions, can be a good building unit for the development of high-performance semiconducting polymers for both organic field-effect transistors and photovoltaic devices. PMID:27877654

  16. 5,10-linked naphthodithiophenes as the building block for semiconducting polymers

    NASA Astrophysics Data System (ADS)

    Osaka, Itaru; Komatsu, Koki; Koganezawa, Tomoyuki; Takimiya, Kazuo

    2014-04-01

    We present new semiconducting polymers incorporating naphtho[1, 2-b:5, 6-b‧] dithiophene (NDT3) and naphtho[2, 1-b:6, 5-b‧] dithiophene (NDT4), which are linked at the naphthalene positions, in the polymer backbone. It is interesting that the trend in the ordering structure and thus charge transport properties are quite different from what were observed in the isomeric polymers where the NDT3 and NDT4 cores are linked at the thiophene α-positions. In the thiophene-linked NDT system, the NDT3-based polymer (PNDT3BT) gave the better ordering in thin films and thus the high charge carrier mobility compared to the NDT4-based polymer (PNDT4BT). In the meantime, in the naphthalene-linked NDT system, the NDT4-based polymer (PNDT4iBT) provided the superior properties. Considering that PNDT4iBT has relatively low highest occupied molecular orbital (HOMO) energy level (-5.2 eV) and moderately high mobilities in the order of 10-2 cm2 V-1 s-1, the NDT4 core, when linked at the naphthalene positions, can be a good building unit for the development of high-performance semiconducting polymers for both organic field-effect transistors and photovoltaic devices.

  17. Methyl chloride via oxyhydrochlorination of methane: A building block for chemicals and fuels from natural gas

    SciTech Connect

    Benson, R.L.; Brown, S.S.D.; Ferguson, S.P.; Jarvis, R.F. Jr.

    1995-12-31

    The objectives of this program are to (a) develop a process for converting natural gas to methyl chloride via an oxyhydrochlorination route using highly selective, stable catalysts in a fixed-bed, (b) design a reactor capable of removing the large amount of heat generated in the process so as to control the reaction, (c) develop a recovery system capable of removing the methyl chloride from the product stream and (d) determine the economics and commercial viability of the process. The general approach has been as follows: (a) design and build a laboratory scale reactor, (b) define and synthesize suitable OHC catalysts for evaluation, (c) select first generation OHC catalyst for Process Development Unit (PDU) trials, (d) design, construct and startup PDU, (e) evaluate packed bed reactor design, (f) optimize process, in particular, product recovery operations, (g) determine economics of process, (h) complete preliminary engineering design for Phase II and (i) make scale-up decision and formulate business plan for Phase II. Conclusions regarding process development and catalyst development are presented.

  18. Branched ZnO nanostructures as building blocks of photoelectrodes for efficient solar energy conversion.

    PubMed

    Chen, Wei; Qiu, Yongcai; Yang, Shihe

    2012-08-21

    ZnO nanotetrapods are distinguished by their unique nanocrystalline geometric form with four tetrahedrally directed arms, which endows them the ability to handily assemble three-dimensional network structures. Such network structures, coupled with the intrinsically excellent electronic properties of the semiconducting ZnO, have proved advantageous for building photoelectrodes in energy conversion devices since they allow fast vectorial electron transport. In this review article, we summarize recent efforts, with partial emphasis on our own, in the development of ZnO nanotetrapod-based devices for solar energy conversion, including dye-sensitized solar cells and photoelectrochemical cells for water splitting. A pure ZnO nanotetrapod network was firstly demonstrated to have excellent charge collection properties even with just physical contacts. Composition design of ZnO nanotetrapods/SnO(2) nanoparticles yielded a high efficiency of 4.91% in flexible DSSCs. More significantly, by secondary branching and nitrogen doping, a record performance for water splitting has been achieved. A perspective on future research directions in ZnO nanotetrapod-based solar energy conversion devices is also discussed together with possible strategies of pursuit. It is hoped that the results obtained so far with the ZnO nanotetrapods could inspire and catalyze future developments of solar energy conversion systems based on branched nanostructural materials, contributing to solving global energy and environmental issues.

  19. Acid rain and our nation`s capital: A guide to effects on buildings and monuments

    SciTech Connect

    McGee, E.

    1997-03-01

    This booklet focuses on acid rain and its impact on our Nation`s capital. This booklet will define acid rain, explain what effects it has on marble and limestone buildings, and show, on a walking tour, some of the places in our Nation`s capital where you can see the impact of acid precipitation.

  20. Fusion of aerial images with mean shift-based upsampled elevation data for improved building block classification

    NASA Astrophysics Data System (ADS)

    Gyftakis, S.; Tsenoglou, T.; Bratsolis, E.; Charou, Eleni; Vassilas, N.

    2014-10-01

    Nowadays there is an increasing demand for detailed 3D modeling of buildings using elevation data such as those acquired from LiDAR airborne scanners. The various techniques that have been developed for this purpose typically perform segmentation into homogeneous regions followed by boundary extraction and are based on some combination of LiDAR data, digital maps, satellite images and aerial orthophotographs. In the present work, our dataset includes an aerial RGB orthophoto, a DSM and a DTM with spatial resolutions of 20cm, 1m and 2m respectively. Next, a normalized DSM (nDSM) is generated and fused with the optical data in order to increase its resolution to 20cm. The proposed methodology can be described as a two-step approach. First, a nearest neighbor interpolation is applied on the low resolution nDSM to obtain a low quality, ragged, elevation image. Next, we performed a mean shift-based discontinuity preserving smoothing on the fused data. The outcome is on the one hand a more homogeneous RGB image, with smoothed terrace coloring while at the same time preserving the optical edges and on the other hand an upsampled elevation data with considerable improvement regarding region filling and "straightness" of elevation discontinuities. Besides the apparent visual assessment of the increased accuracy of building boundaries, the effectiveness of the proposed method is demonstrated using the processed dataset as input to five supervised classification methods. The performance of each method is evaluated using a subset of the test area as ground truth. Comparisons with classification results obtained with the original data demonstrate that preprocessing the input dataset using the mean shift algorithm improves significantly the performance of all tested classifiers for building block extraction.

  1. CdB{sub 10}O{sub 14}(OH){sub 4}·H{sub 2}O with an unprecedented decaborate fundamental building block

    SciTech Connect

    Yang, Dingfeng; Jing, Yan; Zhang, Yang; Liu, Xianming; Lin, Zheshuai; Cong, Rihong; Gao, Wenliang; Yang, Tao

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► CdB{sub 10}O{sub 14}(OH){sub 4}·H{sub 2}O is prepared by boric acid flux method. ► Its structure is solved by single-crystal X-ray diffraction in space group P2{sub 1}/n. ► It possesses an unprecedented decaborate fundamental building block B{sub 10}O{sub 20}. ► Structure features are discussed in detail and compared with other polyborates. -- Abstract: CdB{sub 10}O{sub 14}(OH){sub 4}·H{sub 2}O has been synthesized under boric acid flux condition and characterized by single-crystal X-ray diffraction, infrared spectra, and UV–vis reflectance spectroscopy. It crystallizes in the monoclinic space group P2{sub 1}/n with a = 7.7277(8), b = 18.95(2), c = 9.8616(10) Å, β= 91.454(1)°, V = 1443.7(3) Å. The structure consists of [B{sub 10}O{sub 16}(OH){sub 4}] layers of 9-membered borate rings enclosing Cd{sup 2+} cations. Adjacent borate layers are interconnected via hydrogen bonding to form a 3D network. It possesses an unprecedented decaborate fundamental building block B{sub 10}O{sub 20}. The structure details are discussed together with Sr[B{sub 6}O{sub 9}(OH){sub 2}]·3H{sub 2}O, Pb[B{sub 8}O{sub 11}(OH){sub 4}], Pr[B{sub 8}O{sub 11}(OH){sub 5}], and Nd[B{sub 9}O{sub 13}(OH){sub 4}]·H{sub 2}O, which have correlated FBBs. The band structure calculations show its direct energy band gap of ∼4.68 eV, in consistent with the estimated value (4.77 eV) from UV–vis. In addition, dielectric constants and refractive indexes are also calculated.

  2. Molybdophosphonate clusters as building blocks in the oxomolybdate-organodiphosphonate/cobalt(II)-organoimine system: structural influences of secondary metal coordination preferences and diphosphonate tether lengths.

    PubMed

    Armatas, N Gabriel; Allis, Damian G; Prosvirin, Andrew; Carnutu, Gabriel; O'Connor, Charles J; Dunbar, Kim; Zubieta, Jon

    2008-02-04

    Hydrothermal conditions have been used in the preparation of a series of organic-inorganic hybrid materials of the cobalt-molybdophosphonate family. The reactions of MoO(3), cobalt(II) acetate or cobalt(II) acetylacetonate, tetra-2-pyridylpyrazine (tpyprz), and organodiphosphonic acids H(2)O(3)P(CH(2))nPO(3)H(2) (n = 1-5 and 9) of varying tether lengths yielded compounds of the general type {Co(2)(tpyprz)(H(2)O)(m)}4+/MoxOy{O(3)P(CH(2))(n)PO(3)}z. The recurring theme of the structural chemistry is the incorporation of {Mo(5)O(15)(O(3)PR)(2)}(4-) clusters as molecular building blocks observed in the structures of nine phases (compounds 2-9 and 11). The structural consequences of variations in reaction conditions are most apparent in the series with propylene diphosphonate, where four unique structures 4-7 are observed, including two distinct three-dimensional architectures for compounds 5 and 6 whose formulations differ only in the number of water molecules of crystallization. With pentyldiphosphonate, a second phase 10 is obtained which exhibits a unique cluster building block, the hexamolybdate [Mo(6)O(18){O(3)P(CH(2))(5)PO(3)}](4-). In the case of methylenediphosphonic acid, a third structural motif, the trinuclear {(Mo(3)O(8))(O(3)PCH(2)PO(3))}2- subunit, is observed in compound 1. The structural chemistry of compounds 1-11 of this study is quite distinct from that of the {Ni(2)(tpyprz)(H(2)O)(m)}(4+)/Mo(x)O(y){O(3)P(CH(2))(n)PO(3)}z family, as well as that of the copper-based family. The structural diversity of this general class of materials reflects the coordination preferences of the M(II) sites, the extent of aqua ligation to the M(II) sites, the participation of both phosphate oxygen atoms and molybdate oxo-groups in linking to the M(II) sites, and the variability in the number of attachment sites at the molybdophosphonate clusters. Since the charge densities at the peripheral oxygen atoms of the clusters are quite uniform, the attachment of {M(2)(tpyprz

  3. Achieving high performance non-fullerene organic solar cells through tuning the numbers of electron deficient building blocks of molecular acceptors

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Chen, Yusheng; Chen, Shangshang; Dong, Tao; Deng, Wei; Lv, Lei; Yang, Saina; Yan, He; Huang, Hui

    2016-08-01

    Two analogous dimer and tetramer compounds, SF-PDI2 and SF-PDI4, were designed, theoretically calculated, synthesized, and developed as electron acceptors for organic solar cells. The effects of the number of the electron deficient building blocks on the optical absorption, energy levels, charge transport, morphology, crystallinity, and photovoltaic performance of the molecules were investigated. In combination with two different donors, PTB7-Th and PffBT4T-2OD, the results showed that increasing the numbers of PDI building blocks is beneficial to photovoltaic performance and leads to efficiency over 5%.

  4. A building-block approach to 3D printing a multichannel, organ-regenerative scaffold.

    PubMed

    Wang, Xiaohong; Rijff, Boaz Lloyd; Khang, Gilson

    2015-06-29

    Multichannel scaffolds, formed by rapid prototyping technologies, retain a high potential for regenerative medicine and the manufacture of complex organs. This study aims to optimize several parameters for producing poly(lactic-co-glycolic acid) (PLGA) scaffolds by a low-temperature, deposition manufacturing, three-dimensional printing (3DP, or rapid prototyping) system. Concentration of the synthetic polymer solution, nozzle speed and extrusion rate were analysed and discussed. Polymer solution with a concentration of 12% w/v was determined as optimal for formation; large deviation of this figure failed to maintain the desired structure. The extrusion rate was also modified for better construct quality. Finally, several solid organ scaffolds, such as the liver, with proper wall thickness and intact contour were printed. This study gives basic instruction to design and fabricate scaffolds with de novo material systems, particularly by showing the approximation of variables for manufacturing multichannel PLGA scaffolds. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Xenobiology meets enzymology: Exploring the potential of unnatural building blocks in biocatalysis.

    PubMed

    Budisa, Nediljko; Völler, Jan-Stefan; Koksch, Beate; Acevedo-Rocha, Carlos G; Kubyshkin, Vladimir; Agostini, Federica

    2017-01-13

    Xenobiology (XB) aims to design biological systems endowed with unusual biochemistries, while enzymology concerns the study of enzymes, the workhorses of biocatalysis. Biocatalysis employs enzymes and organisms to perform useful biotransformations in synthetic chemistry and biotechnology. During the past years, the effects of incorporating noncanonical amino acids (ncAAs) into enzymes with potential applications in biocatalysis have been increasingly investigated. Here we provide an overview of the effects of new chemical functionalities that have been introduced into proteins to improve various facets of enzymatic catalysis. We also discuss future research avenues that will complement unnatural mutagenesis with the standard protein-engineering toolbox for producing novel and versatile biocatalysts with applications in synthetic organic chemistry and biotechnology.

  6. Enabling the 2nd Generation in Space: Building Blocks for Large Scale Space Endeavours

    NASA Astrophysics Data System (ADS)

    Barnhardt, D.; Garretson, P.; Will, P.

    Today the world operates within a "first generation" space industrial enterprise, i.e. all industry is on Earth, all value from space is from bits (data essentially), and the focus is Earth-centric, with very limited parts of our population and industry participating in space. We are limited in access, manoeuvring, on-orbit servicing, in-space power, in-space manufacturing and assembly. The transition to a "Starship culture" requires the Earth to progress to a "second generation" space industrial base, which implies the need to expand the economic sphere of activity of mankind outside of an Earth-centric zone and into CIS-lunar space and beyond, with an equal ability to tap the indigenous resources in space (energy, location, materials) that will contribute to an expanding space economy. Right now, there is no comfortable place for space applications that are not discovery science, exploration, military, or established earth bound services. For the most part, space applications leave out -- or at least leave nebulous, unconsolidated, and without a critical mass -- programs and development efforts for infrastructure, industrialization, space resources (survey and process maturation), non-traditional and persistent security situational awareness, and global utilities -- all of which, to a far greater extent than a discovery and exploration program, may help determine the elements of a 2nd generation space capability. We propose a focus to seed the pre-competitive research that will enable global industry to develop the necessary competencies that we currently lack to build large scale space structures on-orbit, that in turn would lay the foundation for long duration spacecraft travel (i.e. key technologies in access, manoeuvrability, etc.). This paper will posit a vision-to-reality for a step wise approach to the types of activities the US and global space providers could embark upon to lay the foundation for the 2nd generation of Earth in space.

  7. Energy Efficiency and Conservation Block Grant (EECBG): Better Buildings Neighborhood Program Final Report

    SciTech Connect

    Donnelly, Kat A.

    2014-01-10

    The Neighbor to Neighbor Energy Challenge (N2N) brought together a consortium of 14 leading clean energy rural, suburban, and low income communities throughout Connecticut. N2N was awarded $4.2 million from the U.S. Department of Energy (DOE) competitive BetterBuildings Neighborhood Program on August 10, 2010 to run a two-year pilot program (plus one year of transition and evaluation) (Award No. EMCBC- 00969-10). N2N tested innovative program models and hypotheses for improving Connecticut’s existing residential energy efficiency programs that are overseen by the ratepayer fund board and administered by CT utilities. N2N’s original goal was to engage 10 percent of households in participating communities to reduce their energy usage by 20 percent through energy upgrades and clean energy measures. N2N planned for customers to complete more comprehensive whole-home energy efficiency and clean energy measures and to achieve broader penetration than existing utility-administered regulated programs. Since this was an ARRA award, we report the following figures on job creation in Table 1. Since N2N is not continuing in its current form, we do not provide figures on job retention. Table 1 N2N Job Creation by Quarter Jobs Created 2010 Q4 6.65 2011 Q1 7.13 2011 Q2 4.98 2011 Q3 9.66 2011 Q4 5.43 2012 Q1 11.11 2012 Q2 6.85 2012 Q3 6.29 2012 Q4 6.77 2013 Q1 5.57 2013 Q2 8.35 2013 Q3 6.52 Total 85.31 The N2N team encountered several gaps in the existing efficiency program performance that hindered meeting N2N’s and DOE’s short-term program goals, as well as the State of Connecticut’s long-term energy, efficiency, and carbon reduction goals. However, despite the slow program start, N2N found evidence of increasing upgrade uptake rates over time, due to delayed customer action of one to two years from N2N introduction to completion of deeper household upgrades. Two main social/behavioral principles have contributed to driving deeper upgrades in CT: 1. Word of mouth

  8. Enaminones as building blocks for the synthesis of substituted pyrazoles with antitumor and antimicrobial activities.

    PubMed

    Riyadh, Sayed M

    2011-02-22

    Novel N-arylpyrazole-containing enaminones 2a,b were synthesized as key intermediates. Reactions of 2a,b with active methylene compounds in acetic acid in the presence of ammonium acetate afforded substituted pyridine derivatives 5a-d. Enaminones 2a,b also reacted with aliphatic amines such as hydrazine hydrate and hydroxylamine hydrochloride to give bipyrazoles 8a,b and pyrazolylisoxazoles 9a,b, respectively. On the other hand, treatment of 2a,b with a heterocyclic amine and its diazonium salt yielded the respective [1,2,4]triazolo[4,3-a]pyrimidines 12a,b and pyrazolylcarbonyl[1,2,4]triazolo-[3,4-c][1,2,4]triazines 14a,b. Moreover, 2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one (17) was prepared via reaction of enaminone 2a with aminothiouracil (15). Cyclocondensation of 17 with the appropriate hydrazonoyl chlorides 18a-c gave the corresponding pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones 21a-c. The cytotoxic effects of compounds 2b, 14a and 17 against human breast cell line (MCF-7) and liver carcinoma cell line (HEPG2) were screened and in both lines they showed inhibition effects comparable to those of 5-fluorouracil, used as a standard. The antimicrobial activity of some products chosen as representative examples was also evaluated.

  9. All-trans retinoic acid-induced, life-threatening complete atrioventricular block.

    PubMed

    Shih, Chen-Hsiang; Wu, Hung-Bo

    2015-05-01

    We report a case of complete atrioventricular block (CAVB) with ventricular asystole and recurrent AVBs due to all-trans retinoic acid (ATRA). A 57-year-old man with acute promyelocytic leukemia was undergoing induction therapy with ATRA and developed episodic seizures with altered consciousness on the 14(th) day and then CAVB followed by cardiac arrest on the 15(th) day. Although he initially recovered after resuscitation, he suffered from recurrent CAVB, which persisted for 3 days despite immediate ATRA discontinuation. He then received ATRA retreatment with reduction of dosage, but a high-degree AVB recurred on the 5(th) day. After discontinuation of ATRA therapy, the patient recovered 3 days later without any cardiovascular event during follow-up. The serial electrocardiogram changes suggested an infra-Hisian block with possible ATRA dose-response relationship. To our knowledge, this is the first established case of ATRA-induced CAVB in the literature. We suggest clinical alertness for this life-threatening complication.

  10. Porous molecular networks formed by the self-assembly of positively-charged trigonal building blocks at the liquid/solid interfaces.

    PubMed

    Tahara, Kazukuni; Abraham, Maria L; Igawa, Kosuke; Katayama, Keisuke; Oppel, Iris M; Tobe, Yoshito

    2014-07-21

    Tris-(2-hydroxybenzylidene)triaminoguanidinium salts having six alkyl chains with proper spacing served as new molecular building blocks for the formation of porous honeycomb networks by van der Waals interaction between interdigitated alkyl chains at the liquid/graphite interfaces.

  11. Asymmetric self-assembly with atmospheric CO2 fixation of a pentanuclear carbonate NiI) complex based on dissimilar building blocks.

    PubMed

    Fondo, Matilde; García-Deibe, Ana M; Ocampo, Noelia; Sanmartín, Jesús; Bermejo, Manuel R

    2007-01-28

    Formation in basic solution of an asymmetric pentanuclear carbonate Ni(II) complex with a compartmental ligand involves atmospheric CO(2) uptake, either by reaction of two slightly different dinuclear precursors that yield its di- and trinuclear "building blocks", or directly, by spontaneous self-organization of metal and ligand starting reactants.

  12. The Building Blocks Collaborative: advancing a life course approach to health equity through multi-sector collaboration.

    PubMed

    Shrimali, Bina Patel; Luginbuhl, Jessica; Malin, Christina; Flournoy, Rebecca; Siegel, Anita

    2014-02-01

    Too many children are born into poverty, often living in disinvested communities without adequate opportunities to be healthy and thrive. Two complementary frameworks-health equity and life course-propose new approaches to these challenges. Health equity strategies seek to improve community conditions that influence health. The life course perspective focuses on key developmental periods that can shift a person's trajectory over the life course, and highlights the importance of ensuring that children have supports in place that set them up for long-term success and health. Applying these frameworks, the Alameda County Public Health Department launched the Building Blocks Collaborative (BBC), a countywide multi-sector initiative to engage community partners in improving neighborhood conditions in low-income communities, with a focus on young children. A broad cross-section of stakeholders, called to action by the state of racial and economic inequities in children's health, came together to launch the BBC and develop a Bill of Rights that highlights the diverse factors that contribute to children's health. BBC partners then began working together to improve community conditions by learning and sharing ideas and strategies, and incubating new collaborative projects. Supportive health department leadership; dedicated staff; shared vision and ownership; a flexible partnership structure; and broad collective goals that build on partners' strengths and priorities have been critical to the growth of the BBC. Next steps include institutionalizing BBC projects into existing infrastructure, ongoing partner engagement, and continued project innovation-to achieve a common vision that all babies have the best start in life.

  13. Copper blocks quinolinic acid neurotoxicity in rats: contribution of antioxidant systems.

    PubMed

    Santamaría, Abel; Flores-Escartín, Abigail; Martínez, Juan Carlos; Osorio, Laura; Galván-Arzate, Sonia; Pedraza-Chaverrí, José; Chaverrí, José Pedraza; Maldonado, Perla D; Medina-Campos, Omar N; Jiménez-Capdeville, María E; Manjarrez, Joaquín; Ríos, Camilo

    2003-08-15

    Reactive oxygen species and oxidative stress are involved in quinolinic acid (QUIN)-induced neurotoxicity. QUIN, a N-methyl-D-aspartate receptor (NMDAr) agonist and prooxidant molecule, produces NMDAr overactivation, excitotoxic events, and direct reactive oxygen species formation. Copper is an essential metal exhibiting both modulatory effects on neuronal excitatory activity and antioxidant properties. To investigate whether this metal is able to counteract the neurotoxic and oxidative actions of QUIN, we administered copper (as CuSO(4)) intraperitoneally to rats (2.5, 5.0, 7.5, and 10.0 mg/kg) 30 min before the striatal infusion of 1 microliter of QUIN (240 nmol). A 5.0 mg/kg CuSO(4) dose significantly increased the copper content in the striatum, reduced the neurotoxicity measured both as circling behavior and striatal gamma-aminobutyric acid (GABA) depletion, and blocked the oxidative injury evaluated as striatal lipid peroxidation (LP). In addition, copper reduced the QUIN-induced decreased striatal activity of Cu,Zn-dependent superoxide dismutase, and increased the ferroxidase activity of ceruloplasmin in cerebrospinal fluid from QUIN-treated rats. However, copper also produced significant increases of plasma lactate dehydrogenase activity and mortality at the highest doses employed (7.5 and 10.0 mg/kg). These results show that at low doses, copper exerts a protective effect on in vivo QUIN neurotoxicity.

  14. Using the fingerprints of solar magnetic reconnection to identify the elemental building blocks of the slow solar wind

    NASA Astrophysics Data System (ADS)

    Kepko, Larry; Viall, Nicholeen M.; Kasper, Justin; Lepri, Sue

    2015-04-01

    While the source of the fast solar wind is well understood to be linked to coronal holes, the source of the slow solar wind has remained elusive. Many previous studies of the slow solar wind have examined trends in the composition and charge states over long time scales and found strong relationships between the solar wind velocity and these plasma parameters. These relationships have been used to constrain models of solar wind source and acceleration. In this study, we take advantage of high time resolution (12 min) measurements of solar wind composition and charge-state abundances recently reprocessed by the ACE Solar Wind Ion Composition Spectrometer (SWICS) science team to probe the timescales of solar wind variability at relatively small scales. We study an interval of slow solar wind containing quasi-periodic 90 minute structures and show that they are remnants of solar magnetic reconnection. Each 90-minute parcel of slow solar wind, though the speed remains steady, exhibits the complete range of charge state and composition variations expected for the entire range of slow solar wind, which is repeated again in the next 90-minute interval. These observations show that previous statistical results break down on these shorter timescales, and impose new and important constraints on models of slow solar wind creation. We conclude by suggesting these structures were created through interchange magnetic reconnection and form elemental building blocks of the slow solar wind. We also discuss the necessity of decoupling separately the process(es) responsible for the release and acceleration.

  15. Identification and characterization of passive safety system and inherent safety feature building blocks for advanced light-water reactors

    SciTech Connect

    Forsberg, C.W.

    1989-01-01

    Oak Ridge National Laboratory (ORNL) is investigating passive and inherent safety options for Advanced Light-Water Reactors (ALWRs). A major activity in 1989 includes identification and characterization of passive safety system and inherent safety feature building blocks, both existing and proposed, for ALWRs. Preliminary results of this work are reported herein. This activity is part of a larger effort by the US Department of Energy, reactor vendors, utilities, and others in the United States to develop improved LWRs. The Advanced Boiling Water Reactor (ABWR) program and the Advanced Pressurized Water Reactor (APWR) program have as goals improved, commercially available LWRs in the early 1990s. The Advanced Simplified Boiling Water Reactor (ASBWR) program and the AP-600 program are developing more advanced reactors with increased use of passive safety systems. It is planned that these reactors will become commercially available in the mid 1990s. The ORNL program is an exploratory research program for LWRs beyond the year 2000. Desired long-term goals for such reactors include: (1) use of only passive and inherent safety, (2) foolproof against operator errors, (3) malevolence resistance against internal sabotage and external assault and (4) walkaway safety. The acronym ''PRIME'' (Passive safety, Resilient operation, Inherent safety, Malevolence resistance, and Extended (walkaway) safety) is used to summarize these desired characteristics. Existing passive and inherent safety options are discussed in this document.

  16. Near-IR BODIPY Dyes à la Carte-Programmed Orthogonal Functionalization of Rationally Designed Building Blocks.

    PubMed

    Gómez-Durán, Cesar F A; Esnal, Ixone; Valois-Escamilla, Ismael; Urías-Benavides, Arlette; Bañuelos, Jorge; López Arbeloa, Iñigo; García-Moreno, Inmaculada; Peña-Cabrera, Eduardo

    2016-01-18

    Herein, we report the synthesis of polyfunctional BODIPY building blocks suitable to be subjected to several reaction sequences with complete chemoselectivity, thereby allowing the preparation of complex BODIPY derivatives in a versatile and programmable manner. The reactions included the Liebeskind-Srogl cross-coupling reaction (LSCC), nucleophilic aromatic substitution (SN Ar), Suzuki, Sonogashira, and Stille couplings, and a desulfitative reduction of the MeS group. This novel synthetic protocol is a powerful route to design a library of compounds with tailored photophysical properties for advanced applications. In this context, it is noteworthy that it offers a straightforward and cost-effective strategy to shift the BODIPY emission deep into the near-infrared spectral region while retaining high fluorescence quantum yields as well as highly efficient and stable laser action. These new dyes outperform the lasing behaviour of dyes considered as benchmarks over the red spectral region, overcoming the important drawbacks associated with these commercial laser dyes, namely low absorption at the standard pump wavelengths (355 and 532 nm) and/or poor photostability.

  17. Hexakis(4-iodophenyl)-peri-hexabenzocoronene- a versatile building block for highly ordered discotic liquid crystalline materials.

    PubMed

    Wu, Jishan; Watson, Mark D; Zhang, Li; Wang, Zhaohui; Müllen, Klaus

    2004-01-14

    Hexakis (4-iodophenyl)-peri-hexabenzocoronene (5), a novel functionalizable mesogenic building block, was prepared by rational multistep synthesis. Although sparingly soluble in common solvents, it can be obtained in pure form and then functionalized via Hagihara-Sonogashira coupling to give a series of highly ordered columnar liquid crystalline molecules 14a-c. The total synthesis involves five 6-fold transformations, all in excellent to near quantitative isolated yields. Their thermotropic liquid crystalline behavior was studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). Compared to the normal alkyl-subsituted hexabenzocoronenes (HBCs), 14a-c exhibit more highly ordered columnar mesophases, including three-dimensionally ordered superstructures (helical columnar mesophase). These could arise from additional intracolumnar pi-pi interactions between, and space-filling requirements introduced by, the rigid-rod side groups. Atomic force microscopy (AFM) revealed self-assembled bundles of columnar aggregates in spin-coated films and isolated several-micron-long nanoribbons composed of a defined number of columns in drop cast films.

  18. Single MoO3 nanoribbon waveguides: good building blocks as elements and interconnects for nanophotonic applications

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Wu, Guoqing; Gu, Fuxing; Zeng, Heping

    2015-11-01

    Exploring new nanowaveguide materials and structures is of great scientific interest and technological significance for optical and photonic applications. In this work, high-quality single-crystal MoO3 nanoribbons (NRs) are synthesized and used for optical guiding. External light sources are efficiently launched into the single MoO3 NRs using silica fiber tapers. It is found that single MoO3 NRs are as good nanowaveguides with loss optical losses (typically less than 0.1 dB/μm) and broadband optical guiding in the visible/near-infrared region. Single MoO3 NRs have good Raman gains that are comparable to those of semiconductor nanowaveguides, but the second harmonic generation efficiencies are about 4 orders less than those of semiconductor nanowaveguides. And also no any third-order nonlinear optical effects are observed at high pump power. A hybrid Fabry-Pérot cavity containing an active CdSe nanowire and a passive MoO3 NR is also demonstrated, and the ability of coupling light from other active nanostructures and fluorescent liquid solutions has been further demonstrated. These optical properties make single MoO3 NRs attractive building blocks as elements and interconnects in miniaturized photonic circuitries and devices.

  19. Short-length carbon nanotubes as building blocks for high dielectric constant materials in the terahertz range

    NASA Astrophysics Data System (ADS)

    Shuba, M. V.; Paddubskaya, A. G.; Kuzhir, P. P.; Maksimenko, S. A.; Flahaut, E.; Fierro, V.; Celzard, A.; Valusis, G.

    2017-03-01

    Due to the high polarizability of finite-length carbon nanotubes (CNTs) in the quasi-static regime, they can be considered as building blocks for the fabrication of high dielectric constant material. Our theoretical estimations, based on an effective medium approach and solutions of a boundary value problem for individual CNT, predict that composite materials comprising short-length CNTs can have very high dielectric constants (up to 300) and low dielectric loss tangents (below 0.03) in the terahertz range. In order to prove this, 500–1000 nm thick films comprising single- and multi-walled CNTs of both long (0.5–2 μm) and short (0.1–0.4 μm) lengths have been fabricated. The analysis, based on the time-domain terahertz spectroscopy in the range 0.2–1.0 THz, demonstrated a decrease in the dielectric loss tangents of the CNT-based materials with a reduction in CNT length. In the terahertz range, the films comprising short-length CNTs had a relative effective permittivity with a large real part (25–136) and dielectric loss tangent (0.35–0.60).

  20. A 50/50 electronic beam splitter in graphene nanoribbons as a building block for electron optics

    NASA Astrophysics Data System (ADS)

    Lima, Leandro R. F.; Hernández, Alexis R.; Pinheiro, Felipe A.; Lewenkopf, Caio

    2016-12-01

    Based on the investigation of the multi-terminal conductance of a system composed of two graphene nanoribbons, in which one is on top of the other and rotated by {{60}\\circ} , we propose a setup for a 50/50 electronic beam splitter that neither requires large magnetic fields nor ultra low temperatures. Our findings are based on an atomistic tight-binding description of the system and on the Green function method to compute the Landauer conductance. We demonstrate that this system acts as a perfect 50/50 electronic beam splitter, in which its operation can be switched on and off by varying the doping (Fermi energy). We show that this device is robust against thermal fluctuations and long range disorder, as zigzag valley chiral states of the nanoribbons are protected against backscattering. We suggest that the proposed device can be applied as the fundamental element of the Hong-Ou-Mandel interferometer, as well as a building block of many devices in electron optics.

  1. Single MoO3 nanoribbon waveguides: good building blocks as elements and interconnects for nanophotonic applications

    PubMed Central

    Zhang, Li; Wu, Guoqing; Gu, Fuxing; Zeng, Heping

    2015-01-01

    Exploring new nanowaveguide materials and structures is of great scientific interest and technological significance for optical and photonic applications. In this work, high-quality single-crystal MoO3 nanoribbons (NRs) are synthesized and used for optical guiding. External light sources are efficiently launched into the single MoO3 NRs using silica fiber tapers. It is found that single MoO3 NRs are as good nanowaveguides with loss optical losses (typically less than 0.1 dB/μm) and broadband optical guiding in the visible/near-infrared region. Single MoO3 NRs have good Raman gains that are comparable to those of semiconductor nanowaveguides, but the second harmonic generation efficiencies are about 4 orders less than those of semiconductor nanowaveguides. And also no any third-order nonlinear optical effects are observed at high pump power. A hybrid Fabry-Pérot cavity containing an active CdSe nanowire and a passive MoO3 NR is also demonstrated, and the ability of coupling light from other active nanostructures and fluorescent liquid solutions has been further demonstrated. These optical properties make single MoO3 NRs attractive building blocks as elements and interconnects in miniaturized photonic circuitries and devices. PMID:26611855

  2. Deprotonated Water Dimers: The Building Blocks of Segmented Water Chains on Rutile RuO2(110)

    SciTech Connect

    Mu, Rentao; Cantu Cantu, David; Glezakou, Vassiliki Alexandra; Lyubinetsky, Igor; Rousseau, Roger J.; Dohnalek, Zdenek

    2015-10-15

    Despite the importance of RuO2 in photocatalytic water splitting and catalysis in general, the interactions of water with even its most stable (110) surface are not well-understood. In this study we employ a combination of high-resolution scanning tunneling microscopy imaging with density functional theory based ab initio molecular dynamics, and we follow the formation and binding of linear water clusters on coordinatively unsaturated ruthenium rows. We find that clusters of all sizes (dimers, trimers, tetramers, extended chains) are stabilized by donating one proton per every two water molecules to the surface bridge bonded oxygen sites, in contrast with water monomers that do not show a significant propensity for dissociation. The clusters with odd number of water molecules are less stable than the clusters with even number, and are generally not observed under thermal equilibrium. For all clusters with even numbers, the dissociated dimers represent the fundamental building blocks with strong intra-dimer hydrogen bonds and only very weak inter-dimer interactions resulting in segmented water chains.

  3. Surface tectonics of nanoporous networks of melamine-capped molecular building blocks formed through interface Schiff-base reactions.

    PubMed

    Liu, Xuan-He; Wang, Dong; Wan, Li-Jun

    2013-10-01

    Control over the assembly of molecules on a surface is of great importance for the fabrication of molecule-based miniature devices. Melamine (MA) and molecules with terminal MA units are promising candidates for supramolecular interfacial packing patterning, owing to their multiple hydrogen-bonding sites. Herein, we report the formation of self-assembled structures of MA-capped molecules through a simple on-surface synthetic route. MA terminal groups were successfully fabricated onto rigid molecular cores with 2-fold and 3-fold symmetry through interfacial Schiff-base reactions between MA and aldehyde groups. Sub-molecular scanning tunneling microscopy (STM) imaging of the resultant adlayer revealed the formation of nanoporous networks. Detailed structural analysis indicated that strong hydrogen-bonding interactions between the MA groups persistently drove the formation of nanoporous networks. Herein, we demonstrate that functional groups with strong hydrogen-bond-formation ability are promising building blocks for the guided assembly of nanoporous networks and other hierarchical 2D assemblies.

  4. Self-assembly properties and dynamics of synthetic proteo-nucleic building blocks in solution and on surfaces.

    PubMed

    Laisne, Aude; Ewald, Maxime; Ando, Toshio; Lesniewska, Eric; Pompon, Denis

    2011-09-21

    Synthetic proteo-nucleic structures (PDNAs) encompassing a single-stranded DNA sequence covalently attached to a redox protein domain able to interact with surface or matrix were designed and characterized. They constitute versatile building blocks alternative to regular DNA for creating scaffolds with optical, electrical, or catalytic properties. PDNAs self-assemble in the presence of complementary oligonucleotides, to form a network of protein domains linked by double-stranded DNA segments. Electrophoretic and hydrodynamic behaviors of PDNAs and corresponding DNA were compared under electrophoresis and gel filtration conditions. Hybridization rates between small and large assemblies were characterized by rapid-mixing experiments. Results showed that the protein part significantly contributes to hydrodynamic behaviors of structures but marginally affects the conformation and hybridization properties of the nucleic domain. PDNA metal-mediated complexes with nitriloacetate-modified phospholipids can diffuse and interact at the surface of vesicles or supported membranes. Surface plasmon resonance analysis of membrane-PDNA interactions indicated that two protein units are required to allow stable surface association and that surface occupancy constrains assembly sizes. High-speed atomic force microscopy illustrated rapid lateral diffusion of assemblies on mica, revealing transient association between noncomplementary PDNA extremities and frequent trapping by surface defects. Regularly organized protein domains were visualized using a larger DNA framework.

  5. Dithiazolo[5,4-b:4',5'-d]phosphole: a highly luminescent electron-accepting building block.

    PubMed

    He, Xiaoming; Woo, Alva Y Y; Borau-Garcia, Javier; Baumgartner, Thomas

    2013-06-03

    A family of highly emissive dithiazolo[5,4-b:4',5'-d]phospholes has been designed and synthesized. The structures of two trivalent P species, as well as their corresponding P oxides, have been confirmed by X-ray crystallography. The parent dithiazolo[5,4-b:4',5'-d]phosphole oxide exhibits strong blue photoluminescence at λem = 442 nm, with an excellent quantum yield efficiency of ϕPL = 0.81. The photophysical properties of these compounds can be easily tuned by extension of the conjugation and modification of the phosphorus center. Compared with the established dithieno[3,2-b:2',3'-d]phosphole system, the incorporation of electronegative nitrogen atoms leads to significantly lowered frontier orbital energy levels, as validated by both electrochemistry and theoretical calculations, thus suggesting that the dithiazolo[5,4-b:4',5'-d]phospholes are valuable, air-stable, n-type conjugated materials. These new building blocks have been further applied to the construction of an extended oligomer with fluorene. Extension of the dithiazolophosphole core with triazole units through click reactions also provides a suitable N,N-chelating moiety for metal binding and a representative molecular species was successfully used as a selective colorimetric and fluorescent sensor for Cu(II) ions.

  6. Total synthesis of woodrosin I--part 1: preparation of the building blocks and evaluation of the glycosylation strategy.

    PubMed

    Fürstner, Alois; Jeanjean, Fabien; Razon, Patrick; Wirtz, Conny; Mynott, Richard

    2003-01-03

    The preparation of three building blocks required for the total synthesis of woodrosin I (1) is outlined, a complex resin glycoside bearing a macrolide ring which spans four of the five sugars of its oligosaccharide backbone. Key steps involve the enantioselective, titanium-catalyzed addition of dipentylzinc to 5-hexenal, the glycosylation of the resulting alcohol 18 with the glucose-derived trichloroacetimidate 7, and further elaboration of the resulting product 19 into disaccharide 22 on treatment with the orthogonally protected glycosyl donor 15. The trichloroacetimidate method is also used for the formation of the second synthon represented by disaccharide 38. A model study shows that the assembly of the pentasaccharidic perimeter of 1 depends critically on the phasing of the glycosylation events between fragments 22, 38 and the rhamnosyl donor 27 due to the severe steric hindrance in the product. A particularly noteworthy finding is the fact that diol 22 can be regioselectively glycosylated at the 3'-OH group in high yield without protection of the neighboring 2'-OH function.

  7. Natural peptides as building blocks for the synthesis of large protein-like molecules with hydrazone and oxime linkages.

    PubMed

    Rose, K; Zeng, W; Regamey, P O; Chernushevich, I V; Standing, K G; Gaertner, H F

    1996-01-01

    Methods are known for the production of synthetic protein-like molecules of nonlinear architecture with molecular masses in the 10-20 kDa range. To synthesize such compounds of higher molecular mass and complexity, chemoselective ligation of natural (as opposed to synthetic) peptide building blocks was studied. In preliminary experiments with model peptides, conditions for the formation of peptide oximes were investigated, and their stability at alkaline pH was examined, to resolve a literature controversy. It was found that low pH (down to 2.1) was suitable for polyoxime formation and that the oxime bond was stable for up to 65 h at pH 8 and for more than 2 h at pH 9. Then, using natural peptides, it was found to be possible to synthesize, and characterize by mass spectrometry, nine-component species with molecular masses > 48 kDa. This is about twice the size of homogeneous artificial proteins previously described. Such complex molecules of defined structure are beginning to find applications as vaccine candidates, as radioimmunodiagnostic agents, and as nonviral gene therapy delivery vehicles.

  8. Could the ethics of institutionalized health care be anything but Kantian? Collecting building blocks for a unifying metaethics.

    PubMed

    Kaldis, Byron

    2005-01-01

    Is a Health Care Ethics possible? Against sceptical and relativist doubts Kantian deontology may advance a challenging alternative affirming the possibility of such an ethics on the condition that deontology be adopted as a total programme or complete vision. Kantian deontology is enlisted to move us from an ethics of two-person informal care to one of institutions. It justifies this affirmative answer by occupying a commanding meta-ethical stand. Such a total programme comprises, on the one hand, a dual-aspect strategy incorporating the macro- (institutional) and micro- (person-to-person) levels while, on the other, it integrates consistently within moral epistemology a meta-ethics with lower-ground moral theories. The article describes the issues to be dealt with and the problems which have to be solved on the way to a unifying theory of that kind (Sections I-III) and indicates elements of Kantian moral philosophy which may serve as building blocks (Section IV). Among these are not only Kant's ideas concerning the moral acting of persons and his ideas concerning civil society and state but also his ideas concerning morality, schematism and religion.

  9. How to build optically active alpha-amino acids.

    PubMed

    Calmes, M; Daunis, J

    1999-01-01

    Various methodologies published in the literature dealing with alpha-amino carboxylic acid asymmetric synthesis are presented in a digest form. In each case, only some recent or most typical works are mentioned.

  10. Relationship Building Blocks

    ERIC Educational Resources Information Center

    Santabarbara, Todd; Erbe, Ryan; Cooper, Scott

    2009-01-01

    Intimate or romantic relationships for young people today play an integral role in their health and quality of life. Between the ages of 11 and 13 students become more interested in the opposite sex and as a result they begin to develop more intimate relationships. Around this age students are learning to deal with these feelings of attraction and…

  11. Genetic Building Blocks

    ERIC Educational Resources Information Center

    Roberg, Ezra

    2004-01-01

    The "Central Dogma" of genetics states that one gene, located in a DNA molecule, is ultimately translated into one protein. As important as this idea is, many teachers shy away from teaching the actual mechanism of gene translation, and many students find the concepts abstract and inaccessible. This article describes a unit, called Genetics…

  12. Biodegradable DNA-brush Block Copolymer Spherical Nucleic Acids Enable Transfection Agent-Free Intracellular Gene Regulation

    PubMed Central

    Zhang, Chuan; Hao, Liangliang; Calabrese, Colin M.; Zhou, Yu; Choi, Chung Hang J.; Xing, Hang; Mirkin, Chad A.

    2015-01-01

    A new strategy for synthesizing spherical nucleic acid (SNA) nanostructures from biodegradable DNA block copolymers is reported. Multiple DNA strands are grafted to one end of a polyester chain (poly-caprolactone) to generate an amphiphilic DNA brush block copolymer (DBBC) structure capable of assembling into spherical micelles in aqueous solution. These novel DBBC-based micelle-SNAs exhibit a higher surface density of nucleic acids compared to micelle structures assembled from an analogous linear DNA block copolymer (DBC), which endows them with the ability to more efficiently enter cells without the need for transfection agents. Importantly, the new SNAs show effective gene regulation without observable cellular toxicity in mammalian cell culture. PMID:26297167

  13. The flavanoide caffeic acid phenethyl ester blocks 6-hydroxydopamine-induced neurotoxicity.

    PubMed

    Noelker, Carmen; Bacher, Michael; Gocke, Petra; Wei, Xing; Klockgether, Thomas; Du, Yansheng; Dodel, Richard

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive loss of dopaminergic (DA) neurons of the substantia nigra pars compacta. 6-Hydroxydopamine (6-OHDA) is specific to dopaminergic neurons in intrastriatal rodent models. It induces neuronal death either via uncoupling mitochondrial oxidative phosphorylation resulting in energy deprivation or alternatively, is associated with its ability to produce hydrogen peroxide, hydroxyl and superoxide radicals. Caffeic acid phenethyl ester (CAPE), an antioxidant flavanoid, has antiviral, anti-inflammatory, antioxidant, and immunomodulatory properties. Recent studies have shown that CAPE has also a neuroprotective effects in ischemia and low potassium-induced neuronal apoptotic models. In cerebellar granule neurons CAPE significantly blocks 6-OHDA mediated cell death (70 microM) in a dose-dependent manner. Furthermore, CAPE was able to modulate the Ca(2+)-induced release of cyctochrome c in isolated liver mitochondria. Caspase-3 activation following 6-OHDA treatment was markedly inhibited in the presence of CAPE. Although the molecular mechanisms associated with CAPE's neuroprotective effects remain to be elucidated in more detail, our results clearly demonstrate a considerable neuroprotective effect of CAPE. Since a mitochondrial insult is a major cause for the degeneration of nigral neurons in PD, we hypothesize that propolis derivatives, in particular CAPE, may have a neuroprotective effect on those cells and may be a promising drug candidate to be taken into in vivo models of PD.

  14. Tumor acidity-sensitive linkage-bridged block copolymer for therapeutic siRNA delivery.

    PubMed

    Xu, Cong-Fei; Zhang, Hou-Bing; Sun, Chun-Yang; Liu, Yang; Shen, Song; Yang, Xian-Zhu; Zhu, Yan-Hua; Wang, Jun

    2016-05-01

    The design of ideal nanoparticle delivery systems should be capable of meeting the requirements of several stages of drug delivery, including prolonged circulation, enhanced accumulation and penetration in the tumor, facilitated cellular internalization and rapid release of the active drug in the tumor cells. However, among the current design strategies, meeting the requirements of one stage often conflicts with the other. Herein, a tumor pH-labile linkage-bridged block copolymer of poly(ethylene glycol) with poly(lacide-co-glycolide) (PEG-Dlinkm-PLGA) was used for siRNA delivery to fulfill all aforementioned requirements of these delivery stages. The obtained siRNA-encapsulating PEG-Dlinkm-PLGA nanoparticle gained efficiently prolonged circulation in the blood and preferential accumulation in tumor sites via the PEGylation. Furthermore, the PEG surface layer was detached in response to the tumor acidic microenvironment to facilitate cellular uptake, and the siRNA was rapidly released within tumor cells due to the hydrophobic PLGA layer. Hence, PEG-Dlinkm-PLGA nanoparticles met the requirements of several stages of drug delivery, and resulted in the enhanced therapeutic effect of the nanoparticular delivery systems.

  15. The Bacillus BioBrick Box: generation and evaluation of essential genetic building blocks for standardized work with Bacillus subtilis

    PubMed Central

    2013-01-01

    Background Standardized and well-characterized genetic building blocks are a prerequisite for the convenient and reproducible assembly of novel genetic modules and devices. While numerous standardized parts exist for Escherichia coli, such tools are still missing for the Gram-positive model organism Bacillus subtilis. The goal of this study was to develop and thoroughly evaluate such a genetic toolbox. Results We developed five BioBrick-compatible integrative B. subtilis vectors by deleting unnecessary parts and removing forbidden restriction sites to allow cloning in BioBrick (RFC10) standard. Three empty backbone vectors with compatible resistance markers and integration sites were generated, allowing the stable chromosomal integration and combination of up to three different devices in one strain. In addition, two integrative reporter vectors, based on the lacZ and luxABCDE cassettes, were BioBrick-adjusted, to enable β-galactosidase and luciferase reporter assays, respectively. Four constitutive and two inducible promoters were thoroughly characterized by quantitative, time-resolved measurements. Together, these promoters cover a range of more than three orders of magnitude in promoter strength, thereby allowing a fine-tuned adjustment of cellular protein amounts. Finally, the Bacillus BioBrick Box also provides five widely used epitope tags (FLAG, His10, cMyc, HA, StrepII), which can be translationally fused N- or C-terminally to any protein of choice. Conclusion Our genetic toolbox contains three compatible empty integration vectors, two reporter vectors and a set of six promoters, two of them inducible. Furthermore, five different epitope tags offer convenient protein handling and detection. All parts adhere to the BioBrick standard and hence enable standardized work with B. subtilis. We believe that our well-documented and carefully evaluated Bacillus BioBrick Box represents a very useful genetic tool kit, not only for the iGEM competition but any other

  16. Building blocks for actively-aligned micro-optical systems in rapid prototyping and small series production

    NASA Astrophysics Data System (ADS)

    Böttger, Gunnar; Queisser, Marco; Arndt-Staufenbiel, Norbert; Schröder, Henning; Lang, K.-D.

    2015-03-01

    In recent years there has been considerable progress in utilizing fully automated machines for the assembly of microoptical systems. Such systems integrate laser sources, optical elements and detectors into tight packages, and efficiently couple light to free space beams, waveguides in optical backplanes, or optical fibers for longer reach transmission. The required electrical-optical and optical components are placed and aligned actively in more than one respect. For one, all active components are actually operated in the alignment process, and, more importantly, the placing of all components is controlled actively by camera systems and power detectors with live feedback for an optimal coupling efficiency. The total number of optical components typically is in the range of 5 to 50, whereas the number of actors with gripping tools for the actual handling and aligning is limited, with little flexibility in the gripping width. The assembly process therefore is strictly sequential and, given that an automated tool changing has not been established in this class of machines yet, there are either limitations in the geometries of components that may be used, or time-consuming interaction by human operators is needed. As a solution we propose and present lasered glass building blocks with standardized gripping geometries that enclose optical elements of various shapes and functionalities. These are cut as free form geometries with green short pulse and CO2 lasers. What seems to add cost at first rather increases freedom of design and adds an economical flexibility to create very hybrid assemblies of various micro-optical assemblies also in small numbers.

  17. Solution processable colloidal nanoplates as building blocks for high-performance electronic thin films on flexible substrates.

    PubMed

    Lin, Zhaoyang; Chen, Yu; Yin, Anxiang; He, Qiyuan; Huang, Xiaoqing; Xu, Yuxi; Liu, Yuan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2014-11-12

    Low-temperature solution-processed electronic materials on plastic substrates are of considerable interest for flexible electronics. Solution dispersible inorganic nanostructures (e.g., zero-dimensional (0D) quantum dots or one-dimensional (1D) nanowires) have emerged as interesting ink materials for low-temperature solution processing of electronic thin films on flexible substrates, but usually with limited performance due to the large number of grain boundaries (0D) or incomplete surface coverage (1D). Here, we report two-dimensional (2D) colloidal nanoplates of layered materials as a new ink material for solution assembly of high-performance electronic thin films. The 2D colloidal nanoplates exhibit few dangling bonds and represent an ideal geometry for the assembly of highly uniform continuous thin films with greatly reduced grain boundaries dictated by large-area conformal plane-plane contact with atomically flat/clean interfaces. It can therefore promise efficient charge transport across neighboring nanoplates and throughout the entire thin film to enable unprecedented electronic performance. We show that Bi2Se3 and Bi2Te3 nanoplates can be synthesized with well-controlled thickness (6-15 nm) and lateral dimension (0.5-3 μm) and can be used for the assembly of highly uniform continuous thin films with a full surface coverage and an excellent room temperature carrier mobility >100 cm(2)·V(-1)·s(-1), approaching that of chemical vapor deposition grown materials. Our study demonstrates a general strategy to using 2D nanoplates as a unique building block for the construction of high-performance electronic thin films on plastic substrates for future flexible electronics and optoelectronics.

  18. Selective nickel-catalyzed conversion of model and lignin-derived phenolic compounds to cyclohexanone-based polymer building blocks.

    PubMed

    Schutyser, Wouter; Van den Bosch, Sander; Dijkmans, Jan; Turner, Stuart; Meledina, Maria; Van Tendeloo, Gustaaf; Debecker, Damien P; Sels, Bert F

    2015-05-22

    Valorization of lignin is essential for the economics of future lignocellulosic biorefineries. Lignin is converted into novel polymer building blocks through four steps: catalytic hydroprocessing of softwood to form 4-alkylguaiacols, their conversion into 4-alkylcyclohexanols, followed by dehydrogenation to form cyclohexanones, and Baeyer-Villiger oxidation to give caprolactones. The formation of alkylated cyclohexanols is one of the most difficult steps in the series. A liquid-phase process in the presence of nickel on CeO2 or ZrO2 catalysts is demonstrated herein to give the highest cyclohexanol yields. The catalytic reaction with 4-alkylguaiacols follows two parallel pathways with comparable rates: 1) ring hydrogenation with the formation of the corresponding alkylated 2-methoxycyclohexanol, and 2) demethoxylation to form 4-alkylphenol. Although subsequent phenol to cyclohexanol conversion is fast, the rate is limited for the removal of the methoxy group from 2-methoxycyclohexanol. Overall, this last reaction is the rate-limiting step and requires a sufficient temperature (>250 °C) to overcome the energy barrier. Substrate reactivity (with respect to the type of alkyl chain) and details of the catalyst properties (nickel loading and nickel particle size) on the reaction rates are reported in detail for the Ni/CeO2 catalyst. The best Ni/CeO2 catalyst reaches 4-alkylcyclohexanol yields over 80 %, is even able to convert real softwood-derived guaiacol mixtures and can be reused in subsequent experiments. A proof of principle of the projected cascade conversion of lignocellulose feedstock entirely into caprolactone is demonstrated by using Cu/ZrO2 for the dehydrogenation step to produce the resultant cyclohexanones (≈80 %) and tin-containing beta zeolite to form 4-alkyl-ε-caprolactones in high yields, according to a Baeyer-Villiger-type oxidation with H2 O2 .

  19. Rational design of hetero-ring-expanded guanine analogs with enhanced properties for modified DNA building blocks.

    PubMed

    Zhang, Jinmei; Cukier, Robert I; Bu, Yuxiang

    2007-07-19

    The properties and modes of recognition of physiological DNAs associated with the four natural nucleobases might be extended, in principle, by the design of non-natural nucleobase derivatives. The goal is an expansion of the genetic alphabet, with the possible outcome of producing new DNAs with improved physical or biological properties. In this work, a new series of hetero-ring-expanded guanine analogs are proposed, and their relevant structural characteristics and electronic properties are determined by density functional theory. The stabilities of the decamer DNA duplexes (dn.dC)10 (where n represents the corresponding expanded guanine analog designed here) are also examined, using molecular dynamics. The simulations show that the designed motifs can form stable DNA-like structures. We determined the pairing energies for the Watson-Crick (WC) hydrogen-bonded dimers between the expanded G-analogs and the natural C, and found that the pairing energies are close to those of the natural GC pair. The calculated adiabatic ionization potentials (IPs) of the size-expanded guanine analogs and their base pairs, and the corresponding vertical ionization potentials, show that some are distinctly smaller than the corresponding natural versions. The HOMO-LUMO energy gaps for most of the size-expanded guanine analogs and their WC base pairs are considerably lower than those of the corresponding natural base and base pairs. Thus, the expanded G bases may be considered as DNA genetic motifs, and they may serve as building blocks for potential biological applications and the development of molecular electronic devices.

  20. Protodeboronation of ortho- and para-phenol boronic acids and application to ortho and meta functionalization of phenols using boronic acids as blocking and directing groups.

    PubMed

    Lee, Chun-Young; Ahn, Su-Jin; Cheon, Cheol-Hong

    2013-12-06

    The first metal-free thermal protodeboronation of ortho- and para-phenol boronic acids in DMSO was developed. The protodeboronation was successfully applied to the synthesis of ortho- and meta-functionalized phenols using the boronic acid moiety as a blocking group and a directing group, respectively. Mechanistic studies suggested that this protodeboronation proceeds through the coordination of water to the boron atom followed by σ-bond metathesis.

  1. Poly(citric acid)-block-poly(ethylene glycol) copolymers--new biocompatible hybrid materials for nanomedicine.

    PubMed

    Naeini, Ashkan Tavakoli; Adeli, Mohsen; Vossoughi, Manouchehr

    2010-08-01

    Linear-dendritic ABA triblock copolymers containing poly(ethylene glycol) (PEG) as B block and hyperbranched poly(citric acid) (PCA) as A blocks were synthesized through polycondensation. The molecular self-assembly of synthesized PCA-PEG-PCA copolymers in water led to formation of nanoparticles and fibers in different sizes and shapes depending on the time and size of PCA blocks. Ten days after dissolving PCA-PEG-PCA copolymers in water, the size of fibers had reached several millimeters. Mixing a water solution of fluorescein as a small guest molecule and PCA-PEG-PCA copolymers led to the encapsulation of fluorescein by products of molecular self-assembly. To investigate their potential application in nanomedicine and to understand the limitations and capabilities of these materials as nanoexcipients in biological systems, different types of short-term in vitro cytotoxicity experiments on the HT1080 cell line (human fibrosarcoma) and hemocompatibility tests were performed. From the clinical editor: This manuscript investigates the potentials of linear-dendritic ABA triblock copolymers containing poly(ethylene glycol) (PEG) as B block and hyperbranched poly(citric acid) (PCA) as A blocks for future applications in nanomedicine.

  2. Mesoporous Bragg reflectors: block-copolymer self-assembly leads to building blocks with well defined continuous pores and high control over optical properties

    NASA Astrophysics Data System (ADS)

    Guldin, S.; Kolle, M.; Stefik, M.; Wiesner, U.; Steiner, U.

    2011-09-01

    Mesoporous distributed Bragg re ectors (MDBRs) exhibit porosity on the sub-optical length scale. This makes them ideally suited as sensing platforms in biology and chemistry as well as for light management in optoelectronic devices. Here we present a new fast forward route for the fabrication of MDBRs which relies on the self-assembling properties of the block copolymer poly(isoprene-block-ethylene oxide) (PI-b-PEO) in combination with sol-gel chemistry. The interplay between structure directing organic host and co-assembled inorganic guest allows the ne tuning of refractive index in the outcome material. The refractive index dierence between the high and low porosity layer can be as high as 0.4, with the optical interfaces being well dened. Following a 30 min annealing protocol after each layer deposition enables the fast and reliable stacking of MDBRs which exhibit a continuous TiO2 network with large accessible pores and high optical quality.

  3. Surface Mechanical and Rheological Behaviors of Biocompatible Poly((D,L-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA-PEG) and Poly((D,L-lactic acid-ran-glycolic acid-ran-ε-caprolactone)-block-ethylene glycol) (PLGACL-PEG) Block Copolymers at the Air-Water Interface

    SciTech Connect

    Kim, Hyun Chang; Lee, Hoyoung; Khetan, Jawahar; Won, You-Yeon

    2016-02-01

    Air–water interfacial monolayers of poly((d,l-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA–PEG) exhibit an exponential increase in surface pressure under high monolayer compression. In order to understand the molecular origin of this behavior, a combined experimental and theoretical investigation (including surface pressure–area isotherm, X-ray reflectivity (XR) and interfacial rheological measurements, and a self-consistent field (SCF) theoretical analysis) was performed on air–water monolayers formed by a PLGA–PEG diblock copolymer and also by a nonglassy analogue of this diblock copolymer, poly((d,l-lactic acid-ran-glycolic acid-ran-caprolactone)-block-ethylene glycol) (PLGACL–PEG). The combined results of this study show that the two mechanisms, i.e., the glass transition of the collapsed PLGA film and the lateral repulsion of the PEG brush chains that occur simultaneously under lateral compression of the monolayer, are both responsible for the observed PLGA–PEG isotherm behavior. Upon cessation of compression, the high surface pressure of the PLGA–PEG monolayer typically relaxes over time with a stretched exponential decay, suggesting that in this diblock copolymer situation, the hydrophobic domain formed by the PLGA blocks undergoes glass transition in the high lateral compression state, analogously to the PLGA homopolymer monolayer. In the high PEG grafting density regime, the contribution of the PEG brush chains to the high monolayer surface pressure is significantly lower than what is predicted by the SCF model because of the many-body attraction among PEG segments (referred to in the literature as the “n-cluster” effects). The end-grafted PEG chains were found to be protein resistant even under the influence of the “n-cluster” effects.

  4. Surface Mechanical and Rheological Behaviors of Biocompatible Poly((D,L-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA-PEG) and Poly((D,L-lactic acid-ran-glycolic acid-ran-ε-caprolactone)-block-ethylene glycol) (PLGACL-PEG) Block Copolymers at the Air-Water Interface.

    PubMed

    Kim, Hyun Chang; Lee, Hoyoung; Khetan, Jawahar; Won, You-Yeon

    2015-12-29

    Air-water interfacial monolayers of poly((D,L-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA-PEG) exhibit an exponential increase in surface pressure under high monolayer compression. In order to understand the molecular origin of this behavior, a combined experimental and theoretical investigation (including surface pressure-area isotherm, X-ray reflectivity (XR) and interfacial rheological measurements, and a self-consistent field (SCF) theoretical analysis) was performed on air-water monolayers formed by a PLGA-PEG diblock copolymer and also by a nonglassy analogue of this diblock copolymer, poly((D,L-lactic acid-ran-glycolic acid-ran-caprolactone)-block-ethylene glycol) (PLGACL-PEG). The combined results of this study show that the two mechanisms, i.e., the glass transition of the collapsed PLGA film and the lateral repulsion of the PEG brush chains that occur simultaneously under lateral compression of the monolayer, are both responsible for the observed PLGA-PEG isotherm behavior. Upon cessation of compression, the high surface pressure of the PLGA-PEG monolayer typically relaxes over time with a stretched exponential decay, suggesting that in this diblock copolymer situation, the hydrophobic domain formed by the PLGA blocks undergoes glass transition in the high lateral compression state, analogously to the PLGA homopolymer monolayer. In the high PEG grafting density regime, the contribution of the PEG brush chains to the high monolayer surface pressure is significantly lower than what is predicted by the SCF model because of the many-body attraction among PEG segments (referred to in the literature as the "n-cluster" effects). The end-grafted PEG chains were found to be protein resistant even under the influence of the "n-cluster" effects.

  5. A new dielectric metamaterial building block with a strong magnetic response in the sub-1.5-micrometer region: silicon colloid nanocavities.

    PubMed

    Shi, Lei; Tuzer, T Umut; Fenollosa, Roberto; Meseguer, Francisco

    2012-11-20

    A new dielectric metamaterial building block based on high refractive index silicon spherical nanocavities with Mie resonances appearing in the near infrared optical region is prepared and characterized. It is demonstrated both experimentally and theoretically that a single silicon nanocavity supports well-defined and robust magnetic resonances, even in a liquid medium environment, at wavelength values up to six times larger than the cavity radius.

  6. Asymmetric dihydroxylations of enynes with a trisubstituted C═C bond. An unprecedented route to γ-lactone building blocks with a quaternary stereocenter.

    PubMed

    Burghart-Stoll, Heike; Kapferer, Tobias; Brückner, Reinhard

    2011-03-04

    En route to a comprehensive set of hydroxylactone building blocks (4R,5R)-, (4R,5S)-, (4S,5R)-, and (4S,5S)-5a, Sharpless asymmetric dihydroxylations of allylic chlorides (E)- and (Z)-9 were performed. They delivered the four stereoisomers of diol 10 with up to 92% ee and absolute configurations, which were proven to be in accordance with the Sharpless mnemonic.

  7. Microwave assisted regioselective synthesis and 2D-NMR studies of novel azoles and azoloazines utilizing fluorine-containing building blocks

    NASA Astrophysics Data System (ADS)

    Al-Bogami, Abdullah S.; Saleh, Tamer S.; Mekky, Ahmed E. M.; Shaaban, Mohamed R.

    2016-10-01

    An efficient regioselective synthesis of novel azoles containing a trifluoromethyl moiety via the 1,3-dipolar cycloaddition reaction under microwave irradiation, using fluorine-containing building blocks methodology was achieved. Furthermore, these novel azoles scaffolds have been employed as the starting material in the synthesis of new azoloazines containing a trifluoromethyl group. An unambiguous structural assignment of the obtained regioisomers was determined using the 2D HMBC NMR techniques as a valuable tool.

  8. Challenges and surprises that arise with nucleic acids during model building and refinement.

    PubMed

    Scott, William G

    2012-04-01

    The process of building and refining crystal structures of nucleic acids, although similar to that for proteins, has some peculiarities that give rise to both various complications and various benefits. Although conventional isomorphous replacement phasing techniques are typically used to generate an experimental electron-density map for the purposes of determining novel nucleic acid structures, it is also possible to couple the phasing and model-building steps to permit the solution of complex and novel RNA three-dimensional structures without the need for conventional heavy-atom phasing approaches.

  9. Building blocks for the development of an interface for high-throughput thin layer chromatography/ambient mass spectrometric analysis: a green methodology.

    PubMed

    Cheng, Sy-Chyi; Huang, Min-Zong; Wu, Li-Chieh; Chou, Chih-Chiang; Cheng, Chu-Nian; Jhang, Siou-Sian; Shiea, Jentaie

    2012-07-17

    Interfacing thin layer chromatography (TLC) with ambient mass spectrometry (AMS) has been an important area of analytical chemistry because of its capability to rapidly separate and characterize the chemical compounds. In this study, we have developed a high-throughput TLC-AMS system using building blocks to deal, deliver, and collect the TLC plate through an electrospray-assisted laser desorption ionization (ELDI) source. This is the first demonstration of the use of building blocks to construct and test the TLC-MS interfacing system. With the advantages of being readily available, cheap, reusable, and extremely easy to modify without consuming any material or reagent, the use of building blocks to develop the TLC-AMS interface is undoubtedly a green methodology. The TLC plate delivery system consists of a storage box, plate dealing component, conveyer, light sensor, and plate collecting box. During a TLC-AMS analysis, the TLC plate was sent to the conveyer from a stack of TLC plates placed in the storage box. As the TLC plate passed through the ELDI source, the chemical compounds separated on the plate would be desorbed by laser desorption and subsequently postionized by electrospray ionization. The samples, including a mixture of synthetic dyes and extracts of pharmaceutical drugs, were analyzed to demonstrate the capability of this TLC-ELDI/MS system for high-throughput analysis.

  10. Cardiac Epithelial-Mesenchymal Transition Is Blocked by Monomethylarsonous Acid (III)

    PubMed Central

    Huang, Tianfang; Barnett, Joey V.; Camenisch, Todd D.

    2014-01-01

    Arsenic exposure during embryonic development can cause ischemic heart pathologies later in adulthood which may originate from impairment in proper blood vessel formation. The arsenic-associated detrimental effects are mediated by arsenite (iAsIII) and its most toxic metabolite, monomethylarsonous acid [MMA (III)]. The impact of MMA (III) on coronary artery development has not yet been studied. The key cellular process that regulates coronary vessel development is the epithelial-mesenchymal transition (EMT). During cardiac EMT, activated epicardial progenitor cells transform to mesenchymal cells to form the cellular components of coronary vessels. Smad2/3 mediated TGFβ2 signaling, the key regulator of cardiac EMT, is disrupted by arsenite exposure. In this study, we compared the cardiac toxicity of MMA (III) with arsenite. Epicardial progenitor cells are 15 times more sensitive to MMA (III) cytotoxicity when compared with arsenite. MMA (III) caused a significant blockage in epicardial cellular transformation and invasion at doses 10 times lower than arsenite. Key EMT genes including TGFβ ligands, TβRIII, Has2, CD44, Snail1, TBX18, and MMP2 were down regulated by MMA (III) exposure. MMA (III) disrupted Smad2/3 activation at a dose 20 times lower than arsenite. Both arsenite and MMA (III) significantly inhibited Erk1/2 and Erk5 phosphorylation. Nuclear translocation of Smad2/3 and Erk5 was also blocked by arsenical exposure. However, p38 activation, as well as smooth muscle differentiation, was refractory to the inhibition by the arsenicals. Collectively, these findings revealed that MMA (III) is a selective disruptor of cardiac EMT and as such may predispose to arsenic-associated cardiovascular disorders. PMID:25145660

  11. Development of valence-directed nanoparticle building blocks on the basis of controlled bio/nano-interfacing chemistry

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Hwan

    The assembly of nanoparticles in controllable and predictable ways would not only aid practical nanoscale assembly, which requires accurate and scalable assembly of large and complex nanoscale structures, but also would increase their utility for many applications, including electronics, optics, sensing and imaging, medical diagnostics, etc. Well-defined and controlled functionality and directionality of the building blocks are essential to actively control the molecular assembly processes at the nanometer scale. Such controls over the functionality and directionality would enable us to construct sophisticated nanostructures to take advantage of the increasing number of available nanocomponents and ultimately to approximate the complexity and the functionality of current microfabrication. We have developed a serial solid-phase placement approach to synthesize anisotropically or symmetrically functionalized gold nanoparticles (AuNPs), in which the functionality and directionality (e.g., numbers, locations, and orientations) of the functional ligands are controlled. Two types of bi-functionalized (bif-) AuNPs were synthesized at a site-specific manner with increased yield and accuracy: (1) homo-bif-AuNPs with two carboxyl groups at ˜180° angle (para-configuration) and (2) hetero-bif-AuNPs with one carboxyl and one amine functional groups at less than 180°, but greater than 90° angle (meta-configuration). With such control, we successfully demonstrated the assembly of intentionally designed one-dimensional (1D) chains with homo-bif-AuNPs and two-dimensional (2D) rings with hetero-bif-AuNPs, confirming the high functional as well as directional selectivity of the functionalized NPs. This study represents an important step towards accurate, reliable, and scaled-up manufacturing of complex nanoscale structures, potentially making 'bottom-up' nanofabrication of practical use. We have further developed the ligand replacement technology to achieve such active controls

  12. All brains are made of this: a fundamental building block of brain matter with matching neuronal and glial masses

    PubMed Central

    Mota, Bruno; Herculano-Houzel, Suzana

    2014-01-01

    How does the size of the glial and neuronal cells that compose brain tissue vary across brain structures and species? Our previous studies indicate that average neuronal size is highly variable, while average glial cell size is more constant. Measuring whole cell sizes in vivo, however, is a daunting task. Here we use chi-square minimization of the relationship between measured neuronal and glial cell densities in the cerebral cortex, cerebellum, and rest of brain in 27 mammalian species to model neuronal and glial cell mass, as well as the neuronal mass fraction of the tissue (the fraction of tissue mass composed by neurons). Our model shows that while average neuronal cell mass varies by over 500-fold across brain structures and species, average glial cell mass varies only 1.4-fold. Neuronal mass fraction varies typically between 0.6 and 0.8 in all structures. Remarkably, we show that two fundamental, universal relationships apply across all brain structures and species: (1) the glia/neuron ratio varies with the total neuronal mass in the tissue (which in turn depends on variations in average neuronal cell mass), and (2) the neuronal mass per glial cell, and with it the neuronal mass fraction and neuron/glia mass ratio, varies with average glial cell mass in the tissue. We propose that there is a fundamental building block of brain tissue: the glial mass that accompanies a unit of neuronal mass. We argue that the scaling of this glial mass is a consequence of a universal mechanism whereby numbers of glial cells are added to the neuronal parenchyma during development, irrespective of whether the neurons composing it are large or small, but depending on the average mass of the glial cells being added. We also show how evolutionary variations in neuronal cell mass, glial cell mass and number of neurons suffice to determine the most basic characteristics of brain structures, such as mass, glia/neuron ratio, neuron/glia mass ratio, and cell densities. PMID:25429260

  13. An fMRI Study of the Impact of Block Building and Board Games on Spatial Ability

    PubMed Central

    Newman, Sharlene D.; Hansen, Mitchell T.; Gutierrez, Arianna

    2016-01-01

    Previous studies have found that block play, board games, and puzzles result in better spatial ability. This study focused on examining the differential impact of structured block play and board games on spatial processing. Two groups of 8-year-old children were studied. One group participated in a five session block play training paradigm and the second group had a similar training protocol but played a word/spelling board game. A mental rotation task was assessed before and after training. The mental rotation task was performed during fMRI to observe the neural changes associated with the two play protocols. Only the block play group showed effects of training for both behavioral measures and fMRI measured brain activation. Behaviorally, the block play group showed improvements in both reaction time and accuracy. Additionally, the block play group showed increased involvement of regions that have been linked to spatial working memory and spatial processing after training. The board game group showed non-significant improvements in mental rotation performance, likely related to practice effects, and no training related brain activation differences. While the current study is preliminary, it does suggest that different “spatial” play activities have differential impacts on spatial processing with structured block play but not board games showing a significant impact on mental rotation performance. PMID:27621714

  14. Ursolic Acid Inhibits Na+/K+-ATPase Activity and Prevents TNF-α-Induced Gene Expression by Blocking Amino Acid Transport and Cellular Protein Synthesis

    PubMed Central

    Yokomichi, Tomonobu; Morimoto, Kyoko; Oshima, Nana; Yamada, Yuriko; Fu, Liwei; Taketani, Shigeru; Ando, Masayoshi; Kataoka, Takao

    2011-01-01

    Pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, induce the expression of a wide variety of genes, including intercellular adhesion molecule-1 (ICAM-1). Ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) was identified to inhibit the cell-surface ICAM-1 expression induced by pro-inflammatory cytokines in human lung carcinoma A549 cells. Ursolic acid was found to inhibit the TNF-α-induced ICAM-1 protein expression almost completely, whereas the TNF-α-induced ICAM-1 mRNA expression and NF-κB signaling pathway were decreased only partially by ursolic acid. In line with these findings, ursolic acid prevented cellular protein synthesis as well as amino acid uptake, but did not obviously affect nucleoside uptake and the subsequent DNA/RNA syntheses. This inhibitory profile of ursolic acid was similar to that of the Na+/K+-ATPase inhibitor, ouabain, but not the translation inhibitor, cycloheximide. Consistent with this notion, ursolic acid was found to inhibit the catalytic activity of Na+/K+-ATPase. Thus, our present study reveals a novel molecular mechanism in which ursolic acid inhibits Na+/K+-ATPase activity and prevents the TNF-α-induced gene expression by blocking amino acid transport and cellular protein synthesis. PMID:24970122

  15. SPECTRAL REFLECTANCE METHOD TO MEASURE ACID DEPOSITION EFFECTS ON BUILDING STONE.

    USGS Publications Warehouse

    Kingston, Marguerite J.; Ager, Cathy M.

    1985-01-01

    As part of the National Acid Precipitation Assessment Program (NAPAP), the U. S. Geological Survey is cooperating with other agencies to test the effects of acid deposition on building stone. A 10-year test-site study has been organized for the purpose of correlating possible stone deterioration with environmental factors. In Summer 1984, slabs of building stone, 3 by 2 by 2 inches, were exposed to the atmosphere at four test sites where the pH of precipitation and other meteorological variables are continuously monitored. This paper examines the development of one experimental technique used in this study - the application of diffuse spectral reflectance methods for laboratory and in situ measurement of those properties of stone which may be affected by acid deposition.

  16. Forensic intelligence framework. Part II: Study of the main generic building blocks and challenges through the examples of illicit drugs and false identity documents monitoring.

    PubMed

    Baechler, Simon; Morelato, Marie; Ribaux, Olivier; Beavis, Alison; Tahtouh, Mark; Kirkbride, K Paul; Esseiva, Pierre; Margot, Pierre; Roux, Claude

    2015-05-01

    The development of forensic intelligence relies on the expression of suitable models that better represent the contribution of forensic intelligence in relation to the criminal justice system, policing and security. Such models assist in comparing and evaluating methods and new technologies, provide transparency and foster the development of new applications. Interestingly, strong similarities between two separate projects focusing on specific forensic science areas were recently observed. These observations have led to the induction of a general model (Part I) that could guide the use of any forensic science case data in an intelligence perspective. The present article builds upon this general approach by focusing on decisional and organisational issues. The article investigates the comparison process and evaluation system that lay at the heart of the forensic intelligence framework, advocating scientific decision criteria and a structured but flexible and dynamic architecture. These building blocks are crucial and clearly lay within the expertise of forensic scientists. However, it is only part of the problem. Forensic intelligence includes other blocks with their respective interactions, decision points and tensions (e.g. regarding how to guide detection and how to integrate forensic information with other information). Formalising these blocks identifies many questions and potential answers. Addressing these questions is essential for the progress of the discipline. Such a process requires clarifying the role and place of the forensic scientist within the whole process and their relationship to other stakeholders.

  17. Establishing an Appropriate Level of Detail (LoD) for a Building Information Model (BIM) - West Block, Parliament Hill, Ottawa, Canada

    NASA Astrophysics Data System (ADS)

    Fai, S.; Rafeiro, J.

    2014-05-01

    In 2011, Public Works and Government Services Canada (PWGSC) embarked on a comprehensive rehabilitation of the historically significant West Block of Canada's Parliament Hill. With over 17 thousand square meters of floor space, the West Block is one of the largest projects of its kind in the world. As part of the rehabilitation, PWGSC is working with the Carleton Immersive Media Studio (CIMS) to develop a building information model (BIM) that can serve as maintenance and life-cycle management tool once construction is completed. The scale and complexity of the model have presented many challenges. One of these challenges is determining appropriate levels of detail (LoD). While still a matter of debate in the development of international BIM standards, LoD is further complicated in the context of heritage buildings because we must reconcile the LoD of the BIM with that used in the documentation process (terrestrial laser scan and photogrammetric survey data). In this paper, we will discuss our work to date on establishing appropriate LoD within the West Block BIM that will best serve the end use. To facilitate this, we have developed a single parametric model for gothic pointed arches that can be used for over seventy-five unique window types present in the West Block. Using the AEC (CAN) BIM as a reference, we have developed a workflow to test each of these window types at three distinct levels of detail. We have found that the parametric Gothic arch significantly reduces the amount of time necessary to develop scenarios to test appropriate LoD.

  18. Fast and reversible lithium-induced electrochemical alloying in tin-based composite oxide hierarchical microspheres assembled by nanoplate building blocks

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Wen, Zhenhai; Li, Jinghong

    To benefit from the large capacity gain advantages offered by lithium-induced electrochemical alloying and to overcome poor kinetics, a novel concept to tackle such issues by using porous hierarchical microspheres with an interconnected network of nanoplate building blocks, has been introduced and demonstrated with Sn 1.0P 1.17O 4.72 glass as an example. Such desired three-dimensional microarchitectures with exciting nanosize effects can be exploited to fabricate next generation of lithium-ion batteries where outstanding rate capability and sustained reversible capacity are achieved.

  19. Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s with functional carbonate building blocks. 1. Chemical synthesis and their structural and physical characterization.

    PubMed

    Yang, Jing; Hao, Qinghui; Liu, Xiaoyun; Ba, Chaoyi; Cao, Amin

    2004-01-01

    This study presents chemical synthesis, structural, and physical characterization of novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s P(BS-co-CC) bearing functional carbonate building blocks. First, five kinds of six-membered cyclic carbonate monomers, namely, trimethylene carbonate (TMC), 1-methyl-1,3-trimethylene carbonate (MTMC), 2,2-dimethyl-1,3-trimethylene carbonate (DMTMC), 5-benzyloxytrimethylene carbonate (BTMC), and 5-ethyl-5-benzyloxymethyl trimethylene carbonate (EBTMC), were well prepared from ethyl chloroformate and corresponding diols at 0 degrees C in THF solution with our modified synthetic strategies. Then, a series of new P(BS-co-CC)s were synthesized at 210 degrees C through a simple combination of poly-condensation and ring-opening-polymerization (ROP) of hydroxyl capped PBS macromers and the prepared carbonate monomers, and titanium tetra-isopropoxide Ti(i-OPr)4 was used as a more suitable catalyst of 5 candidate catalysts which could concurrently catalyze poly-condensation and ROP. By means of NMR, GPC, FTIR, and thermal analytical instruments, macromolecular structures and physical properties have been characterized for these aliphatic poly(ester carbonate)s. The experimental results indicated that novel biodegradable P(BS-co-CC)s were successfully synthesized with number average molecular weight Mn ranging from 24.3 to 99.6 KDa and various CC molar contents without any detectable decarboxylation and that the more bulky side group was attached to a cyclic carbonate monomer, the lower reactivity for its copolymerization would be observed. The occurrences of 13C NMR signal splitting of succinyl carbonyl attributed to the BS building blocks could be proposed due to the randomized sequences of BS and CC building blocks. FTIR characterization indicated two distinct absorption bands at 1716 and 1733 approximately 1735 cm(-1), respectively, stemming from carbonyl stretching modes for corresponding BS and CC units. With

  20. Titanocene(III)-catalyzed 6-exo versus 7-endo cyclizations of epoxypolyprenes: efficient control and synthesis of versatile terpenic building blocks.

    PubMed

    Justicia, José; Jiménez, Tania; Miguel, Delia; Contreras-Montoya, Rafael; Chahboun, Rachid; Alvarez-Manzaneda, Enrique; Collado-Sanz, Daniel; Cárdenas, Diego J; Cuerva, Juan M

    2013-10-18

    In this article, a complete study on the selectivity of titanocene(III) cyclization of epoxypolyprenes is presented. The requirements for the formation of six- or seven-membered rings during these cyclizations are determined, taking into account the different substitution pattern in the epoxypolyprene precursor. Thus, a complete selectivity to 6-exo or 7-endo cyclization process has been achieved, yielding mono-, bi-, and even tricyclic compounds, constituting a new and efficient access to this type of derivative. Additionally, this procedure opens the possibility to prepare excellent building blocks for the synthesis of polycyclic compounds with a trisubstituted oxygenated function, which is present in several natural terpenes.

  1. Record high electron mobility of 6.3 cm² V⁻¹ s⁻¹ achieved for polymer semiconductors using a new building block.

    PubMed

    Sun, Bin; Hong, Wei; Yan, Zhuangqing; Aziz, Hany; Li, Yuning

    2014-05-01

    A new electron acceptor building block, 3,6-di(pyridin-2-yl)pyrrolo[3,4-c ]pyrrole-1,4(2H ,5H)-dione (DBPy), is used to construct a donor-acceptor polymer, PDBPyBT. This polymer exhibits a strong self-assembly capability, to form highly crystalline and oriented thin films with a short π-π stacking distance of 0.36 nm. PDBPyBT shows ambipolar charge-transport performance in organic thin-film transistors, reaching a record high electron-mobility value of 6.30 cm(2) V(-1) s(-1).

  2. The building blocks of a 'Liveable Neighbourhood': Identifying the key performance indicators for walking of an operational planning policy in Perth, Western Australia.

    PubMed

    Hooper, Paula; Knuiman, Matthew; Foster, Sarah; Giles-Corti, Billie

    2015-11-01

    Planning policy makers are requesting clearer guidance on the key design features required to build neighbourhoods that promote active living. Using a backwards stepwise elimination procedure (logistic regression with generalised estimating equations adjusting for demographic characteristics, self-selection factors, stage of construction and scale of development) this study identified specific design features (n=16) from an operational planning policy ("Liveable Neighbourhoods") that showed the strongest associations with walking behaviours (measured using the Neighbourhood Physical Activity Questionnaire). The interacting effects of design features on walking behaviours were also investigated. The urban design features identified were grouped into the "building blocks of a Liveable Neighbourhood", reflecting the scale, importance and sequencing of the design and implementation phases required to create walkable, pedestrian friendly developments.

  3. The solubilization of fatty acids in systems based on block copolymers and nonionic surfactants

    NASA Astrophysics Data System (ADS)

    Mirgorodskaya, A. B.; Yatskevich, E. I.; Zakharova, L. Ya.

    2010-12-01

    The solubilizing action of micellar, microemulsion, and polymer-colloid systems formed on the basis of biologically compatible amphiphilic polymers and nonionic surfactants on capric, lauric, palmitic, and stearic acids was characterized quantitatively. Systems based on micelle forming oxyethyl compounds increased the solubility of fatty acids by more than an order of magnitude. Acid molecules incorporated into micelles increased their size and caused structural changes. Solubilization was accompanied by complete or partial destruction of intrinsic acid associates and an increase in their p K a by 1.5-2 units compared with water.

  4. Energy Efficiency and Conservation Block Grant (EECBG) - Better Buildings Neighborhood Program at Greater Cincinnati Energy Alliance: Home Performance with Energy Star® and Better Buildings Performance

    SciTech Connect

    Holzhauser, Andy; Jones, Chris; Faust, Jeremy; Meyer, Chris; Van Divender, Lisa

    2013-12-30

    The Greater Cincinnati Energy Alliance (Energy Alliance) is a nonprofit economic development agency dedicated to helping Greater Cincinnati and Northern Kentucky communities reduce energy consumption. The Energy Alliance has launched programs to educate homeowners, commercial property owners, and nonprofit organizations about energy efficiency opportunities they can use to drive energy use reductions and financial savings, while extending significant focus to creating/retaining jobs through these programs. The mission of the Energy Alliance is based on the premise that investment in energy efficiency can lead to transformative economic development in a region. With support from seven municipalities, the Energy Alliance began operation in early 2010 and has been among the fastest growing nonprofit organizations in the Greater Cincinnati/Northern Kentucky area. The Energy Alliance offers two programs endorsed by the Department of Energy: the Home Performance with ENERGY STAR® Program for homeowners and the Better Buildings Performance Program for commercial entities. Both programs couple expert guidance, project management, and education in energy efficiency best practices with incentives and innovative energy efficiency financing to help building owners effectively invest in the energy efficiency, comfort, health, longevity, and environmental impact of their residential or commercial buildings. The Energy Alliance has raised over $23 million of public and private capital to build a robust market for energy efficiency investment. Of the $23 million, $17 million was a direct grant from the Department of Energy Better Buildings Neighborhood Program (BBNP). The organization’s investments in energy efficiency projects in the residential and commercial sector have led to well over $50 million in direct economic activity and created over 375,000 hours of labor created or retained. In addition, over 250 workers have been trained through the Building Performance Training

  5. Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance.

    PubMed

    Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin

    2015-08-19

    Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications.

  6. Synthesis of a Glucuronic Acid‐Containing Thioglycoside Trisaccharide Building Block and Its Use in the Assembly of Cryptococcus Neoformans Capsular Polysaccharide Fragments†

    PubMed Central

    Guazzelli, Lorenzo; Ulc, Rebecca

    2015-01-01

    Abstract As part of an ongoing project aimed at identifying protective capsular polysaccharide epitopes for the development of vaccine candidates against the fungal pathogen Cryptococcus neoformans, the synthesis and glycosylation properties of a naphthalenylmethyl (NAP) orthogonally protected trisaccharide thioglycoside, a common building block for construction of serotype B and C capsular polysaccharide structures, were investigated. Ethyl (benzyl 2,3,4‐tri‐O‐benzyl‐β‐d‐glucopyranosyl‐ uronate)‐(1→2)‐[2,3,4‐tri‐O‐benzyl‐β‐d‐xylopyranosyl‐(1→4)]‐6‐O‐benzyl‐3‐O‐(2‐naphthalenylmethyl)‐1‐thio‐α‐d‐mannopyranoside was prepared and used both as a donor and an acceptor in glycosylation reactions to obtain spacer equipped hexa‐ and heptasaccharide structures suitable either for continued elongation or for deprotection and printing onto a glycan array or conjugation to a carrier protein. The glycosylation reactions proceeded with high yields and α‐selectivity, proving the viability of the building block approach also for construction of 4‐O‐xylosyl‐containing C. neoformans CPS structures. PMID:27308199

  7. Efficient synthetic strategy to construct three-dimensional 4f-5d networks using neutral two-dimensional layers as building blocks.

    PubMed

    Zhou, Hu; Yuan, Ai-Hua; Qian, Su-Yan; Song, You; Diao, Guo-Wang

    2010-07-05

    The reaction of neutral two-dimensional (2D) layer Tb(H(2)O)(5)W(CN)(8) with pyrazine in the acetonitrile solution has led to a 3D bimetallic complex, Tb(H(2)O)(4)(pyrazine)(0.5)W(CN)(8) (1). In the structure of 1, the eight-coordinated W center adopts a slightly distorted dodecahedron, while the Tb center exhibits a nine-coordinated slightly distorted tricapped trigonal prism. The Tb(3+) atoms and the [W(CN)(8)](3-) units are linked in alternating fashion in the ab crystallographic plane, resulting in an infinite 2D corrugated layers. The linear bis-monodentate pyrazine ligands acting as pillars link adjacent layers along the c axis to form an extended 3D open framework. The possible formation mechanism is proposed, and the temperature has played a crucial role for the formation of 1. Magnetic measurements revealed the presence of ferromagnetic interaction between Tb(III) and W(V) centers. 1 marks the first structural pattern using the neutral 2D layer as building block and the first 3D complex with Ln(III)-[W(V)(CN)](8) found in octacyanometallate-based system. Such a novel and effective building-block methodology will provide a new attractive path forward in developing functionalities of 3D 4f-5d system and may provide an opportunity to obtain 3D magnet in 4f-5d assembly.

  8. Illumination pupil optimization in 0.33NA EUVL by intensity balancing for semi-iso dark field two-bar M1 building blocks

    NASA Astrophysics Data System (ADS)

    Last, T.; de Winter, L.; van Adrichem, P.; Finders, J.

    2016-10-01

    We will shed light on the optimization of lithographic metrics for the semi-isolated dark field two-bar logic building block. Under standard D90Y illumination this building block suffers from large mask 3D induced relative focus dependent CD asymmetries. Such behavior limits its overlapping process window and gives rise to untenable full wafer CDU and intra-field pattern shifts. We have found that besides a Ta absorber thickness reduction an illumination pupil optimization is necessary to fully remove these CD asymmetries. The pupil optimization is achieved by relating the aerial image decomposition (here: symmetrization and balancing of intensities across the diffracted orders) with lithographic metrics per pupil plane location. The resulting pupil allows us (i) to lift the focus-dependent CD asymmetries and (ii) to co-optimize a number of lithographic metrics such as overlapping process window, contrast, non-telecentricity and pattern shift. The importance of subsidiary conditions (e.g. symmetry of the pupil, required DOF) will be discussed.

  9. Genotoxicity testing of three monohaloacetic acids in TK6 cells using the cytokinesis-block micronucleus assay.

    PubMed

    Liviac, Danae; Creus, Amadeu; Marcos, Ricard

    2010-09-01

    Chemical disinfection of water generates harmful chemical compounds, known as disinfection by-products (DBPs). One class of DBPs is constituted by haloacetic acids (HAAs), the second major group in prevalence (after trihalomethanes) detected in finished drinking water. In this article, we report the results obtained in the evaluation of the chromosome damage induced by three monohaloacetic acids, namely iodoacetic acid (IAA), bromoacetic acid (BAA) and chloroacetic acid (CAA). To evaluate the induction of chromosome damage, we used the cytokinesis-block micronucleus test that measures the ability of genotoxic agents to induce both clastogenic and/or aneugenic effects. No previous data exist on the effects of these compounds on human chromosomes. We tested five doses of each HAA, in addition to the negative and positive controls. The highest dose tested for each HAA was that immediately lower than the dose producing total cytotoxicity. Our results show that none of the three HAAs tested was able to increase significantly the frequency of micronucleus in binucleated TK6 cells, the rank order in decreasing cytotoxicity was IAA > BAA > CAA.

  10. Dispersion polymerization of styrene using a polystyrene/poly(L-glutamic acid) block copolymer as a stabilizer.

    PubMed

    Itoh, Tomomichi; Komada, Seiji; Ihara, Eiji; Inoue, Kenzo

    2012-12-15

    A block copolymer (PS-b-poly(L-Glu)) composed of polystyrene and poly(l-glutamic acid) was used as a stabilizer for dispersion polymerization of styrene. When dispersion polymerization of styrene was conducted at 70°C in 80% dimethylformamide-water with 0.5 wt% PS-b-poly(L-Glu), spherical polystyrene particles with D(n)=0.72 μm and narrow size distribution were obtained. Whereas AIBN concentration did not have any effects on particle size, molecular weight of the polystyrene particles was strongly dependent on the initiator concentration. As concentration of the PS-b-poly(L-Glu) increased from 0.2 to 1.0 wt%, particle size decreased from D(n)=0.91 to 0.69 μm with keeping surface area occupied by one poly(L-glutamic acid) chain about S=50 nm(2). On the other hand, an increase in initial concentration of styrene from 2 to 20 wt% caused an increase in particle size from D(n)=0.48 to 1.36 μm and a decrease in surface area per poly(L-glutamic acid) block from S=91 to 45 nm(2). Colloidal stability of the polystyrene particles in aqueous solution was responsive to pH due to the surface-grafted poly(L-glutamic acid). For dispersion polymerization of styrene, the PS-b-poly(L-Glu) functions as both a stabilizer and a surface modifier.

  11. Screening for perfluoroalkyl acids in consumer products, building materials and wastes.

    PubMed

    Bečanová, Jitka; Melymuk, Lisa; Vojta, Šimon; Komprdová, Klára; Klánová, Jana

    2016-12-01

    Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a large group of important chemical compounds with unique and useful physico-chemical properties, widely produced and used in many applications. However, due to the toxicity, bioaccumulation and long-range transport potential of certain PFASs, they are of significant concern to scientists and policy makers. To assess human exposure to PFASs, it is necessary to understand the concentrations of these emerging contaminants in our environment, and particularly environments where urban population spend most of their time, i.e. buildings and vehicles. A total of 126 samples of building materials, consumer products, car interior materials and wastes were therefore analyzed for their content of key PFASs - 15 perfluoroalkyl acids (PFAAs). At least one of the target PFAAs was detected in 88% of all samples. The highest concentration of Σ15PFAAs was found in textile materials (77.61 μg kg(-1)), as expected, since specific PFAAs are known to be used for textile treatment during processing. Surprisingly, PFAAs were also detected in all analyzed composite wood building materials, which were dominated by perfluoroalkyl carboxylic acids with 5-8 carbons in the chain (Σ4PFCAs up to 32.9 μg kg(-1)). These materials are currently widely used for building refurbishment, and this is the first study to find evidence of the presence of specific PFASs in composite wood materials. Thus, in addition to consumer products treated with PFASs, materials used in the construction of houses, schools and office buildings may also play an important role in human exposure to PFASs.

  12. How Solids Can Be Obtained from the Molecular [Mo 2S 2O 2] 2+ Building Block

    NASA Astrophysics Data System (ADS)

    Sécheresse, Francis; Cadot, Emmanuel; Dolbecq, Anne

    2000-06-01

    Self-condensation of the [Mo2S2O2]2+ building unit under addition of OH- ions gave the neutral cyclic [Mo12S12O12 (OH)12(H2O)6] wheel. In the presence of assembling groups such as phosphates, arsenates, and oxalates, the Mo2-building unit led to anionic wheels differing by their nuclearity, shape, and charge. Solids were derived by tuning the type of associated cations ranging from isolated species to 3D arrangements and layered structures. By functionalization of the [Mo2S2O2]2+ precursor by oxalate, discrete compounds having open or cyclic structures as well as infinite solids were specifically designed.

  13. Frequencies of amino acid strings in globular protein sequences indicate suppression of blocks of consecutive hydrophobic residues

    PubMed Central

    Schwartz, Russell; Istrail, Sorin; King, Jonathan

    2001-01-01

    Patterns of hydrophobic and hydrophilic residues play a major role in protein folding and function. Long, predominantly hydrophobic strings of 20–22 amino acids each are associated with transmembrane helices and have been used to identify such sequences. Much less attention has been paid to hydrophobic sequences within globular proteins. In prior work on computer simulations of the competition between on-pathway folding and off-pathway aggregate formation, we found that long sequences of consecutive hydrophobic residues promoted aggregation within the model, even controlling for overall hydrophobic content. We report here on an analysis of the frequencies of different lengths of contiguous blocks of hydrophobic residues in a database of amino acid sequences of proteins of known structure. Sequences of three or more consecutive hydrophobic residues are found to be significantly less common in actual globular proteins than would be predicted if residues were selected independently. The result may reflect selection against long blocks of hydrophobic residues within globular proteins relative to what would be expected if residue hydrophobicities were independent of those of nearby residues in the sequence. PMID:11316883

  14. Synthesis of amino acid block-copolymer imprinted chiral mesoporous silica and its acoustically-induced optical Kerr effects

    SciTech Connect

    Paik, Pradip; Mastai, Yitzhak; Kityk, Iwan; Rakus, Piort; Gedanken, Aharon

    2012-08-15

    Chiral mesoporous SiO{sub 2} (CMS) have been synthesized and studied the Acoustically-Induced Optical Kerr Effects (AIOKE) and the results have been compared with non-chiral mesoporous silica. The CMS with controllable pore sizes (of {approx}3 nm) and high surface areas of ca. 650 m{sup 2}g{sup -1} was synthesized by mimicking the intrinsic chirality of the amino acid block copolymers. The chiral mesoporous materials were characterized through HRTEM, BET, small-angle XRD, {sup 29}Si-NMR and circular dichroism. AIOKE measurements have been performed using an Er:glass 20 ns laser with a 10 Hz frequency repetition. The optimal AIOKE results of the CMS were achieved for 9.7% of the chromophore in the matrices. We found that the AIOKE for the CMS mimicked with chiral block copolymers is quite high compared to the non-chiral SiO{sub 2}. A difference in AIOKE for these two compounds is observed, enabling CMS that can be used for the design of the acoustically-operated quantum electronic devices. - Graphical abstract: Novel chiral mesoporous SiO{sub 2} (CMS) is showing Acoustically-Induced Optical Kerr Effects (AIOKE). Different in AIOKE of two mesoporous materials is observed, enabling CMS can be used for the design of the acoustically-operated quantum electronic devices.Highlights: Black-Right-Pointing-Pointer Chiral mesoporous SiO{sub 2} (CMS) synthesized with amino acid block copolymers. Black-Right-Pointing-Pointer The Acoustically-induced Optical Kerr Effects (AIOKE) of chiral mesoporous SiO{sub 2} studied. Black-Right-Pointing-Pointer AIOKE very high for CMS compared to non chiral SiO{sub 2}. Black-Right-Pointing-Pointer CMS can be used in acoustically-operated quantum electronic devices.

  15. Polypeptide Point Modifications with Fatty Acid and Amphiphilic Block Copolymers for Enhanced Brain Delivery

    PubMed Central

    Batrakova, Elena V.; Vinogradov, Serguei V.; Robinson, Sandra M.; Niehoff, Michael L.; Banks, William A.; Kabanov, Alexander V.

    2009-01-01

    There is a tremendous need to enhance delivery of therapeutic polypeptides to the brain to treat disorders of the central nervous system (CNS). The brain delivery of many polypeptides is severely restricted by the blood—brain barrier (BBB). The present study demonstrates that point modifications of a BBB-impermeable polypeptide, horseradish peroxidase (HRP), with lipophilic (stearoyl) or amphiphilic (Pluronic block copolymer) moieties considerably enhance the transport of this polypeptide across the BBB and accumulation of the polypeptide in the brain in vitro and in vivo. The enzymatic activity of the HRP was preserved after the transport. The modifications of the HRP with amphiphilic block copolymer moieties through degradable disulfide links resulted in the most effective transport of the HRP across in vitro brain microvessel endothelial cell monolayers and efficient delivery of HRP to the brain. Stearoyl modification of HRP improved its penetration by about 60% but also increased the clearance from blood. Pluronic modification using increased penetration of the BBB and had no significant effect on clearance so that uptake by brain was almost doubled. These results show that point modification can improve delivery of even highly impermeable polypeptides to the brain. PMID:16029020

  16. Novel L-lactic acid biosensors based on conducting polypyrrole-block copolymer nanoparticles.

    PubMed

    Sun, Chong; Wang, Daoying; Zhang, Muhan; Ni, Yanxiu; Shen, Xiaohui; Song, Youchao; Geng, Zhiming; Xu, Weimin; Liu, Fang; Mao, Chun

    2015-02-07

    The development of advanced nanomaterials for the highly efficient electrical detection of biological species has attracted great attention. Here, novel polypyrrole-Pluronic F127 nanoparticles (PPy-F127 NPs) with conducting and biocompatibility properties were synthesized and used to construct a L-lactic acid biosensor that could be applied in biochemical assays. The PPy-F127 NPs were characterized by transmission electron microscopy (TEM), elemental analysis and UV-vis spectroscopy. Lactate oxidase (LOx) structure variation on the PPy-F127 NPs was investigated by circular dichroism (CD). The cyclic voltammetric results indicated that LOx immobilized on the PPy-F127 NPs exhibited direct electron transfer reaction with a formal potential value (E(0)') of 0.154 V vs. SCE. Moreover, the biosensor had good electrocatalytic activity toward L-lactic acid with a wide linear range (0.015-37.5 mM) and a low detection limit of 0.0088 mM. The regression equation was I (μA) = 0.02353c (mM) + 1.4135 (R(2) = 0.9939). The L-lactic acid biosensor had a good anti-interference property towards uric acid (UA), ascorbic acid (AA), glucose and cysteine. The idea and method provide a promising platform for the rapid development of biosensors that can be used in the detection of biological species.

  17. Ellagic acid induces novel and atypical PKC isoforms and promotes caspase-3 dependent apoptosis by blocking energy metabolism.

    PubMed

    Mishra, Sudha; Vinayak, Manjula

    2014-01-01

    Antioxidant ellagic acid is a herbal polyphenolic compound shown to possess growth-inhibiting and apoptotic activities in cancer. Protein kinase C (PKC) plays an important role in cell proliferation, apoptosis, and differentiation. Apoptosis of tumor cells is induced by inactivation of glycolytic enzyme of anaerobic metabolism, lactate dehydrogenase (LDH)-A, and by activating apoptotic protein caspase-3 via PKCδ. The present study aims to analyze the role of ellagic acid on regulation of novel and atypical isozymes of PKC to modulate apoptosis and anaerobic metabolism to prevent lymphoma growth as its role on classical PKCs is reported earlier. Expression of novel and atypical isozymes of PKC, activity of PKCδ, expression and activity of caspase-3, and LDH-A have been analyzed. Expression is measured by RT-PCR, activities of PKCδ as level of its catalytic fragment, caspase-3 as level of its p17 fragment, and LDH-A by specific staining. Lymphoma bearing mice were treated with 3 different doses of ellagic acid. The treatment enhanced expression of all novel and atypical PKCs, activity and expression of caspase-3, and activity of PKCδ but decreased activity and expression of LDH-A. Our results suggest that ellagic acid induces apoptosis via novel and atypical PKCs in association with caspase-3 and induces cancer cell death by blocking the energy metabolism.

  18. Nanoconstructions Based on Spatially Ordered Nucleic Acid Molecules

    NASA Astrophysics Data System (ADS)

    Yevdokimov, Yu. M.

    Different strategies for the design of nanoconstructions whose building blocks are both linear molecules of double-stranded nucleic acids and nucleic acid molecules fixed in the spatial structure of particles of liquid-crystalline dispersions are described.

  19. Bainbridge Energy Challenge. Energy efficiency and conservation block grant (EECBG) - Better buildings neighborhood program. Final Technical Report

    SciTech Connect

    Kraus, Yvonne X.

    2014-02-14

    RePower Bainbridge and Bremerton (RePower) is a residential energy-efficiency and conservation program designed to foster a sustainable, clean, and renewable energy economy. The program was a 3.5 year effort in the cities of Bainbridge Island and Bremerton, Washington, to conserve and reduce energy use, establish a trained home performance trade ally network, and create local jobs. RePower was funded through a $4.8 million grant from the US Department of Energy, Better Buildings Program. The grant’s performance period was August 1, 2010 through March 30, 2014.

  20. Orthogonal Synthesis of Xeno Nucleic Acids.

    PubMed

    Fiers, Guillaume; Chouikhi, Dalila; Oswald, Laurence; Al Ouahabi, Abdelaziz; Chan-Seng, Delphine; Charles, Laurence; Lutz, Jean-François

    2016-12-12

    Sequence-defined peptide triazole nucleic acids (PTzNA) were synthesized by means of a solid-phase orthogonal "AB+CD" iterative strategy. In this approach, AB and CD building blocks containing carboxylic acid (A), azide (B), alkyne (C), and primary amine (D) functions are assembled together by successive copper-catalyzed azide-alkyne cycloaddition (CuAAC) and acid-amine coupling steps. Different PTzNA genetic sequences were prepared using a library of eight building blocks (i.e., four AB and four CD building blocks).

  1. Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

    NASA Astrophysics Data System (ADS)

    Cheng, Jing; Lawson, Richard A.; Yeh, Wei-Ming; Jarnagin, Nathan D.; Peters, Andrew; Tolbert, Laren M.; Henderson, Clifford L.

    2012-03-01

    Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (Mw=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L0) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which

  2. An Electron-Deficient Building Block Based on the B←N Unit: An Electron Acceptor for All-Polymer Solar Cells.

    PubMed

    Dou, Chuandong; Long, Xiaojing; Ding, Zicheng; Xie, Zhiyuan; Liu, Jun; Wang, Lixiang

    2016-01-22

    A double B←N bridged bipyridyl (BNBP) is a novel electron-deficient building block for polymer electron acceptors in all-polymer solar cells. The B←N bridging units endow BNBP with fixed planar configuration and low-lying LUMO/HOMO energy levels. As a result, the polymer based on BNBP units (P-BNBP-T) exhibits high electron mobility, low-lying LUMO/HOMO energy levels, and strong absorbance in the visible region, which is desirable for polymer electron acceptors. Preliminary all-polymer solar cell (all-PSC) devices with P-BNBP-T as the electron acceptor and PTB7 as the electron donor exhibit a power conversion efficiency (PCE) of 3.38%, which is among the highest values of all-PSCs with PTB7 as the electron donor.

  3. Fluorene-Based Copolymers Containing Dinaphtho-s-indacene as New Building Blocks for High-Efficiency and Color-Stable Blue LEDs.

    PubMed

    Guo, Xin; Cheng, Yanxiang; Xie, Zhiyuan; Geng, Yanhou; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

    2009-05-19

    By incorporating a new building block, 7,7,15,15-tetraoctyldinaphtho-s-indacene (NSI), into the backbone of poly(9,9-dioctylfluorene) (PFO), a novel series of blue light-emitting copolymers (PFO-NSI) have been developed. The insertion of the NSI unit into the PFO backbone leads to the increase of local effective conjugation length, to form low-energy fluorene-NSI-fluorene (FNF) segments that serve as exciton trapping sites, to which the energy transfers from the high-energy PFO segments. This causes these copolymers to show red-shifted emissions compared with PFO, with a high efficiency and good color stability and purity. The best device performance with a luminance efficiency of 3.43 cd · A(-1) , a maximum brightness of 6 539 cd · m(-2) , and CIE coordinates of (0.152, 0.164) was achieved.

  4. A Solution-Processable Molecule using Thieno[3,2-b]thiophene as Building Block for Efficient Organic Solar Cells.

    PubMed

    Wei, Huan; Chen, Weichao; Han, Liangliang; Wang, Ting; Bao, Xichang; Li, Xiaoyun; Liu, Jie; Zhou, Yuanhang; Yang, Renqiang

    2015-08-01

    A solution-processed acceptor-π-donor-π-acceptor (A-π-D-π-A) type small molecule, namely DCATT, has been designed and synthesized for the application as donor material in organic solar cells. The fused aromatic unit thieno[3,2-b]thiophene (TT) flanked with thiophene is applied as π bridge, while 4,8-bisthienyl substituted benzodithiophene (BDT) and 2-ethylhexyl cyanoacetate are chosen as the central building block and end group, respectively. Introduction of fused ring to the small molecule enhances the conjugation length of the main chain, and gives a strong tendency to form π-π stacking with a large overlapping area which favors to high charge carrier transport. Small-molecule organic solar cells based on blends of DCATT and fullerene acceptor exhibit power conversion efficiencies as high as 5.20 % under the illumination of AM 1.5G, 100 mW cm(-2) .

  5. Enantioselective ProPhenol-Catalyzed Addition of 1,3-Diynes to Aldehydes to Generate Synthetically Versatile Building Blocks and Diyne Natural Products

    PubMed Central

    Trost, Barry M.; Chan, Vincent S.; Yamamoto, Daisuke

    2010-01-01

    A highly enantioselective method for the catalytic addition of terminal 1,3-diynes to aldehydes was developed using our dinuclear zinc ProPhenol (1) system. Furthermore, triphenylphosphine oxide was found to interact synergistically with the catalyst to substantially enhance the chiral recognition. The generality of this catalytic transformation was demonstrated with aryl, α,β-unsaturated and saturated aldehydes, of which the latter were previously limited in alkynyl zinc additions. The chiral diynol products are also versatile building blocks that can be readily elaborated; this was illustrated through highly selective trans-hydrosilylations, which enabled the synthesis of a β-hydroxyketone and enyne. Additionally, the development of this method allowed for the rapid total syntheses of several biologically important diynol-containing natural products. PMID:20307084

  6. Magnetic stray-field studies of a single Cobalt nanoelement as a component of the building blocks of artificial square spin ice

    NASA Astrophysics Data System (ADS)

    Pohlit, Merlin; Porrati, Fabrizio; Huth, Michael; Ohno, Yuzo; Ohno, Hideo; Müller, Jens

    2016-02-01

    We use Focused Electron Beam Deposition (FEBID) to directly write Cobalt magnetic nanoelements onto a micro-Hall magnetometer, which allows for high-sensitivity measurements of the magnetic stray field emanating from the samples. In a previous study [M. Pohlit et al., J. Appl. Phys. 117 (2015) 17C746] [21] we investigated thermal dynamics of an individual building block (nanocluster) of artificial square spin ice. In this work, we compare the results of this structure with interacting elements to the switching of a single nanoisland. By analyzing the survival function of the repeatedly prepared state in a given temperature range, we find thermally activated switching dynamics. A detailed analysis of the hysteresis loop reveals a metastable microstate preceding the overall magnetization reversal of the single nanoelement, also found in micromagnetic simulations. Such internal degrees of freedom may need to be considered, when analyzing the thermal dynamics of larger spin ice configurations on different lattice types.

  7. Proposed and existing passive and inherent safety-related structures, systems, and components (building blocks) for advanced light-water reactors

    SciTech Connect

    Forsberg, C.W.; Moses, D.L.; Lewis, E.B.; Gibson, R.; Pearson, R.; Reich, W.J.; Murphy, G.A.; Staunton, R.H.; Kohn, W.E.

    1989-10-01

    A nuclear power plant is composed of many structures, systems, and components (SSCs). Examples include emergency core cooling systems, feedwater systems, and electrical systems. The design of a reactor consists of combining various SSCs (building blocks) into an integrated plant design. A new reactor design is the result of combining old SSCs in new ways or use of new SSCs. This report identifies, describes, and characterizes SSCs with passive and inherent features that can be used to assure safety in light-water reactors. Existing, proposed, and speculative technologies are described. The following approaches were used to identify the technologies: world technical literature searches, world patent searches, and discussions with universities, national laboratories and industrial vendors. 214 refs., 105 figs., 26 tabs.

  8. Chemical tricks to stabilize silanones and their heavier homologues with E=O bonds (E=Si-Pb): from elusive species to isolable building blocks.

    PubMed

    Xiong, Yun; Yao, Shenglai; Driess, Matthias

    2013-04-15

    In contrast to the well-established chemistry of ketones (R2C=O), the reactivity of the elusive heavier congeners R2E=O (E=Si, Ge, Sn, Pb) is far less explored because of the high polarity of the E=O bonds and hence their tendency to oligomerize with no activation barrier. Very recently, great advances have been achieved in the synthesis of isolable compounds with E=O bonds, including the investigation of donor-stabilized isolable silanones and the first stable "genuine" germanone. These compounds show drastically different reactivities compared to ketones and represent versatile building blocks in silicon-oxygen and germanium-oxygen chemistry. This and other exciting achievements are described in this Minireview.

  9. Large scale synthesis and regioselective protection schemes of ethyl 2-azido-2-deoxy-1-thio-α-d-cellobioside for preparation of heparin thiodisaccharide building blocks.

    PubMed

    Sheerin, Kevin; Guazzelli, Lorenzo; Oscarson, Stefan

    2017-02-22

    Crystalline acetylated ethyl 2-azido-2-deoxy-1-thio-α-d-cellobioside has been prepared on a multigram scale from cellobiose in an overall yield of 23% with no chromatography required and converted after deacetylation into the 4',6'-O-benzylidene and 4',6'-O-benzylidene-6-O-TBDMS protected derivatives. Applying a number of regioselective benzylation methods on these gave access to a variety of regioselectively protected derivatives, both mono-ols (2'- and 3-OH), diols (2',6-, 2',3-, and 3,6-di-OH), and triols (2',3,6- and 2',3',3-tri-OH). A number of these derivatives were further processed by benzoylation followed by removal or opening of the benzylidene acetal and selective oxidation of the exposed primary alcohol to give heparin building block intermediates comprising a range of possible sulfation patterns.

  10. Silver(I) 1,3,5-Triaza-7-phosphaadamantane Coordination Polymers Driven by Substituted Glutarate and Malonate Building Blocks: Self-Assembly Synthesis, Structural Features, and Antimicrobial Properties.

    PubMed

    Jaros, Sabina W; Guedes da Silva, M Fátima C; Florek, Magdalena; Smoleński, Piotr; Pombeiro, Armando J L; Kirillov, Alexander M

    2016-06-20

    Three new bioactive silver(I) coordination polymers formulated as [Ag2(μ2-PTA)(μ3-PTA)(μ2-pga)(H2O)]n·6H2O (1), [Ag2(μ2-PTA)(μ3-PTA)(Hpmal)2]n·2H2O (2), and [Ag(μ3-PTA) (Hdmga)]n (3) were self-assembled from Ag2O, 1,3,5-triaza-7-phosphaadamantane (PTA), and a substituted dicarboxylic acid (3-phenylglutaric acid (H2pga), phenylmalonic acid (H2pmal), or 3,3-dimethylglutaric acid (H2dmga)) as an ancillary ligand. Compounds 1-3 were fully characterized by IR and NMR spectroscopy, ESI-MS(±), elemental analysis, and single-crystal X-ray diffraction, revealing that their architectural and topological diversity is governed by structural modulation of a dicarboxylate building block. The structures vary from a 1D cyclic chain with the SP 1-periodic net (4,4)(0,2) topology in 2 to distinct 2D metal-organic layers with the cem-d and hcb topologies in 1 and 3, respectively. In addition, compounds 1-3 exhibit a notable antimicrobial efficiency against a panel of common Gram-negative (E. coli and P. aeruginosa) and Gram-positive (S. aureus) bacteria and yeast (C. albicans). The best normalized minimum inhibitory concentrations (normalized MIC) of 11-23 nmol mL(-1) (for bacterial strains) or 68 nmol mL(-1) (for a yeast strain) are shown by compound 2, and the eventual structure-bioactivity correlations are discussed.

  11. Core-shell nanoparticles as building blocks for the bottom-up production of functional nanocomposites: PbTe-PbS thermoelectric properties.

    PubMed

    Ibáñez, Maria; Zamani, Reza; Gorsse, Stéphane; Fan, Jiandong; Ortega, Silvia; Cadavid, Doris; Morante, Joan Ramon; Arbiol, Jordi; Cabot, Andreu

    2013-03-26

    The bottom-up assembly of nanocrystals provides access to a three-dimensional composition control at the nanoscale not attainable by any other technology. In particular, colloidal nanoheterostructures, with intrinsic multiphase organization, are especially appealing building blocks for the bottom-up production of nanocomposites. In the present work, we use PbTe-PbS as the model material system and thermoelectricity as the paradigmatic application to investigate the potential of the bottom-up assembly of core-shell nanoparticles to produce functional nanocomposites. With this goal in mind, a rapid, high-yield and scalable colloidal synthetic route to prepare grams of PbTe@PbS core-shell nanoparticles with unprecedented narrow size distributions and exceptional composition control is detailed. PbTe@PbS nanoparticles were used as building blocks for the bottom-up production of PbTe-PbS nanocomposites with tuned composition. In such PbTe-PbS nanocomposites, synergistic nanocrystal doping effects result in up to 10-fold higher electrical conductivities than in pure PbTe and PbS nanomaterials. At the same time, the acoustic impedance mismatch between PbTe and PbS phases and a partial phase alloying provide PbTe-PbS nanocomposites with strongly reduced thermal conductivities. As a result, record thermoelectric figures of merit (ZT) of ∼1.1 were obtained from undoped PbTe and PbS phases at 710 K. These high ZT values prove the potential of the proposed processes to produce efficient functional nanomaterials with programmable properties.

  12. Oocyte maturation in Xenopus laevis is blocked by the hormonal herbicide, 2,4-dichlorophenoxy acetic acid.

    PubMed

    Stebbins-Boaz, Barbara; Fortner, Katherine; Frazier, Jessie; Piluso, Suzanne; Pullen, Samuel; Rasar, Melissa; Reid, William; Sinclair, Kristin; Winger, Elisa

    2004-02-01

    Oocyte maturation is dependent on a complex program of morphological, ultrastructural, and biochemical signaling events, and if disrupted could lead to decreased fertility and population decline. The in vitro sensitivity of amphibian oocytes and oocyte maturation to plant growth factor and widely used hormonal herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was examined in this study to determine its potential impact on early development and possible contribution to the global amphibian decline. Progesterone, which acts through a membrane receptor, triggers meiotic maturation in full grown (stage VI) Xenopus oocytes, characterized by cytoskeletal reorganization, nuclear dissolution, chromosome condensation, and spindle formation. Biochemically, the Mos/MAPK/MPF signaling pathway is activated, in part dependent on translational activation of specific maternal mRNAs such as c-Mos. Light microscopy revealed unusual asymmetric morphotypes in oocytes exposed to 2,4-D alone characterized by a white spot and bulge, termed coning, in the animal pole where the germinal vesicle (nucleus) persisted intact. Treatment of oocytes with cytochalasin B, a microfilament inhibitor, blocked these morphotypes but nocodazole, a microtubule depolymerizing agent, did not. Confocal microscopy showed that 2,4-D, itself, caused substantial depolymerization of perinuclear microtubules. Importantly, 2,4-D blocked progesterone-induced maturation as measured by the lack of nuclear breakdown, confirmed by the lack of Mos expression, MPF activation, and cytoplasmic polyadenylation of cyclin B1 mRNA. However, Western blot analysis and U0126 inhibitor studies showed that 2,4-D, either alone or in the presence of progesterone, induced MAPK phosphorylation through MAPKK. These results show that 2,4-D disrupts oocyte cytoskeletal organization and blocks maturation while stimulating an independent MAPK signaling pathway.

  13. Analysis of Sporulation Mutants II. Mutants Blocked in the Citric Acid Cycle

    PubMed Central

    Fortnagel, Peter; Freese, Ernst

    1968-01-01

    Sporulation mutants that were unable to incorporate uracil during the developmental period recovered this capacity with the addition of ribose and in most cases with the addition of glutamate. Of the mutants that responded to both ribose and glumate, all but three also responded to citrate, and all but five responded to acetate. One of the exceptional strains was deficient in aconitase and another one in aconitase and isocitrate dehydrogenase; both required glutamate for growth. For the mutants which did not respond to glutamate, the products made from 14C-glutamate were determined by thin-layer chromatography. Significant differences were found which enabled the identification of mutant blocks. The deficiency of the corresponding enzyme activity was verified. Several mutants were deficient in α-ketoglutarate dehydrogenase, and one lacked succinic dehydrogenase. These mutants could still grow on glucose as sole carbon source, but not on glutamate. The intact Krebs cycle is therefore not required for vegetative growth of aerobic Bacillis subtilis, but it is indispensable for sporulation. Images PMID:4967197

  14. Cation-mediated optical resolution and anticancer activity of chiral polyoxometalates built from entirely achiral building blocks

    SciTech Connect

    Zhang, Zhi-Ming; Duan, Xiaopin; Yao, Shuang; Wang, Zhishu; Lin, Zekai; Li, Yang-Guang; Long, La-Sheng; Wang, En-Bo; Lin, Wenbin

    2016-01-01

    We report the crystallization of homochiral polyoxometalate (POM) macroanions {CoSb6O4(H2O)3[Co(hmta)SbW8O31]3}15- (1, hmta = hexamethylenetetramine) via the counter cation-mediated chiral symmetry breaking and asymmetric autocatalytic processes. In the presence of low Co2+ concentrations both Δ- and Λ-enantiomers of 1 formed in the reaction, crystallizing into the racemic crystal rac-1. At a high Co2+ concentration, the polyoxoanion enantiomers showed a high level of chiral recognition via H-bonding interactions to crystallize into enantiopure crystals of Δ- or Λ-[Co(H2O)6{CoSb6O4(H2O)3[Co(hmta)SbW8O31]3}]13-. During crystallization, a microscale symmetry-breaking event and a nonlinear asymmetric autocatalysis process make the enantiomers crystallize in different batches, which provides an opportunity to isolate the homochiral bulk materials. The defined structures of the racemic and homochiral crystals thus provide a molecular-level illustration that H-bonding interactions are responsible for such high-level chiral recognition, in a process similar to the supramolecular chirality frequently observed in biology. These POM macroanions showed a high cytotoxicity against various cancer cells, particularly ovarian cancer cells. The antitumor activity of these compounds resulted at least in part from the activation of the apoptotic pathways, as shown by the flow cytometry, Annexin V staining, DNA ladder, and TUNEL assay, likely by blocking the cell cycle and complexing with proteins in cells. The POM macroanions reported herein provide promising and novel antitumor agents for the potential treatment of various cancers.

  15. Participatory Approach to Long-Term Socio-Economic Scenarios as Building Block of a Local Vulnerability and Risk Assessment Tool - The Case Study Lienz (East-Tyrol)

    NASA Astrophysics Data System (ADS)

    Meyer, Ina; Eder, Brigitte; Hama, Michiko; Leitner, Markus

    2016-04-01

    Risks associated with climate change are mostly still understood and analyzed in a sector- or hazard-specific and rarely in a systemic, dynamic and scenario-based manner. In addition, socio-economic trends are often neglected in local vulnerability and risk assessments although they represent potential key determinants of risk and vulnerability. The project ARISE (Adaptation and Decision Support via Risk Management Through Local Burning Embers) aims at filling this gap by applying a participatory approach to socio-economic scenario building as building block of a local vulnerability assessment and risk management tool. Overall, ARISE aims at developing a decision support system for climate-sensitive iterative risk management as a key adaptation tool for the local level using Lienz in the East-Tyrol as a test-site City. One central building block is participatory socio-economic scenario building that - together with regionalized climate change scenarios - form a centrepiece in the process-oriented assessment of climate change risks and vulnerability. Major vulnerabilities and risks may stem from the economic performance, the socio-economic or socio-demographic developments or changes in asset exposition and not from climate change impacts themselves. The IPCC 5th assessment report underlines this and states that for most economic sectors, the impact of climate change may be small relative to the impacts of other driving forces such as changes in population growth, age, income, technology, relative prices, lifestyle, regulation, governance and many other factors in the socio-economy (Arent et al., 2014). The paper presents the methodology, process and results with respect to the building of long-term local socio-economic scenarios for the City of Lienz and the surrounding countryside. Scenarios were developed in a participatory approach using a scenario workshop that involved major stakeholders from the region. Participatory approaches are increasingly recognized as

  16. De novo synthesis of a 2-acetamido-4-amino-2,4,6-trideoxy-D-galactose (AAT) building block for the preparation of a Bacteroides fragilis A1 polysaccharide fragment.

    PubMed

    Pragani, Rajan; Stallforth, Pierre; Seeberger, Peter H

    2010-04-02

    Zwitterionic polysaccharides (ZPSs) are potent T-cell activators that naturally occur on the cell surface of bacteria and show potential as immunostimulatory agents. An unusual, yet important component of many ZPSs is 2-acetamido-4-amino-2,4,6-trideoxy-D-galactose (AAT). AAT building block 2 was prepared via a de novo synthesis from N-Cbz-L-threonine 5. Furthermore, building block 2 was used to synthesize disaccharide 15 that constitutes a fragment of zwitterionic polysaccharide A1 (PS A1) found in Bacteroides fragilis.

  17. Hybrid metal-coordinate transient networks: using bio-inspired building blocks to engineer the mechanical properties of physical hydrogels

    NASA Astrophysics Data System (ADS)

    Grindy, Scott; Barrett, Devin; Messersmith, Phillip; Holten-Andersen, Niels

    2014-03-01

    Recently, metal-coordinate complex crosslinks have been suggested to contribute to the self-healing properties of mussel byssi. Two specific amino acid derivatives - 3,4 dihydroxy-L-phenylalanine (dopa) and histidine (his) - are known to form coordinate complexes with trivalent and divalent ions (respectively) in aqueous solutions. We show here that, by functionalizing poly(ethylene glycol) polymers with dopa and his we are (1) able to characterize the fundamental kinetics and energetics of each specific metal-ligand pair using small amplitude oscillatory shear rheology and (2) create hybrid networks using various mixtures of metals and ligands. From this information, we can design gels with specific target mechanical properties by tailoring the amounts and types of metal-ligand crosslinks present in the gel network, resulting in the ability to engineer the mechanical relaxation spectrum. This work provides basic understanding necessary to intelligently design materials which incorporate metal-ligand crosslinks in more complex architectures.

  18. Potential of bioethanol as a chemical building block for biorefineries: preliminary sustainability assessment of 12 bioethanol-based products.

    PubMed

    Posada, John A; Patel, Akshay D; Roes, Alexander; Blok, Kornelis; Faaij, André P C; Patel, Martin K

    2013-05-01

    The aim of this study is to present and apply a quick screening method and to identify the most promising bioethanol derivatives using an early-stage sustainability assessment method that compares a bioethanol-based conversion route to its respective petrochemical counterpart. The method combines, by means of a multi-criteria approach, quantitative and qualitative proxy indicators describing economic, environmental, health and safety and operational aspects. Of twelve derivatives considered, five were categorized as favorable (diethyl ether, 1,3-butadiene, ethyl acetate, propylene and ethylene), two as promising (acetaldehyde and ethylene oxide) and five as unfavorable derivatives (acetic acid, n-butanol, isobutylene, hydrogen and acetone) for an integrated biorefinery concept.

  19. Decoding how a soil bacterium extracts building blocks and metabolic energy from ligninolysis provides road map for lignin valorization

    PubMed Central

    Varman, Arul M.; He, Lian; Follenfant, Rhiannon; Wu, Weihua; Wemmer, Sarah; Wrobel, Steven A.; Tang, Yinjie J.; Singh, Seema

    2016-01-01

    Sphingobium sp. SYK-6 is a soil bacterium boasting a well-studied ligninolytic pathway and the potential for development into a microbial chassis for lignin valorization. An improved understanding of its metabolism will help researchers in the engineering of SYK-6 for the production of value-added chemicals through lignin valorization. We used 13C-fingerprinting, 13C metabolic flux analysis (13C-MFA), and RNA-sequencing differential expression analysis to uncover the following metabolic traits: (i) SYK-6 prefers alkaline conditions, making it an efficient host for the consolidated bioprocessing of lignin, and it also lacks the ability to metabolize sugars or organic acids; (ii) the CO2 release (i.e., carbon loss) from the ligninolysis-based metabolism of SYK-6 is significantly greater than the CO2 release from the sugar-based metabolism of Escherichia coli; (iii) the vanillin catabolic pathway (which is the converging point of majority of the lignin catabolic pathways) is coupled with the tetrahydrofolate-dependent C1 pathway that is essential for the biosynthesis of serine, histidine, and methionine; (iv) catabolic end products of lignin (pyruvate and oxaloacetate) must enter the tricarboxylic acid (TCA) cycle first and then use phosphoenolpyruvate carboxykinase to initiate gluconeogenesis; and (v) 13C-MFA together with RNA-sequencing differential expression analysis establishes the vanillin catabolic pathway as the major contributor of NAD(P)H synthesis. Therefore, the vanillin catabolic pathway is essential for SYK-6 to obtain sufficient reducing equivalents for its healthy growth; cosubstrate experiments support this finding. This unique energy feature of SYK-6 is particularly interesting because most heterotrophs rely on the transhydrogenase, the TCA cycle, and the oxidative pentose phosphate pathway to obtain NADPH. PMID:27634497

  20. Decoding how a soil bacterium extracts building blocks and metabolic energy from ligninolysis provides road map for lignin valorization.

    PubMed

    Varman, Arul M; He, Lian; Follenfant, Rhiannon; Wu, Weihua; Wemmer, Sarah; Wrobel, Steven A; Tang, Yinjie J; Singh, Seema

    2016-10-04

    Sphingobium sp. SYK-6 is a soil bacterium boasting a well-studied ligninolytic pathway and the potential for development into a microbial chassis for lignin valorization. An improved understanding of its metabolism will help researchers in the engineering of SYK-6 for the production of value-added chemicals through lignin valorization. We used (13)C-fingerprinting, (13)C metabolic flux analysis ((13)C-MFA), and RNA-sequencing differential expression analysis to uncover the following metabolic traits: (i) SYK-6 prefers alkaline conditions, making it an efficient host for the consolidated bioprocessing of lignin, and it also lacks the ability to metabolize sugars or organic acids; (ii) the CO2 release (i.e., carbon loss) from the ligninolysis-based metabolism of SYK-6 is significantly greater than the CO2 release from the sugar-based metabolism of Escherichia coli; (iii) the vanillin catabolic pathway (which is the converging point of majority of the lignin catabolic pathways) is coupled with the tetrahydrofolate-dependent C1 pathway that is essential for the biosynthesis of serine, histidine, and methionine; (iv) catabolic end products of lignin (pyruvate and oxaloacetate) must enter the tricarboxylic acid (TCA) cycle first and then use phosphoenolpyruvate carboxykinase to initiate gluconeogenesis; and (v) (13)C-MFA together with RNA-sequencing differential expression analysis establishes the vanillin catabolic pathway as the major contributor of NAD(P)H synthesis. Therefore, the vanillin catabolic pathway is essential for SYK-6 to obtain sufficient reducing equivalents for its healthy growth; cosubstrate experiments support this finding. This unique energy feature of SYK-6 is particularly interesting because most heterotrophs rely on the transhydrogenase, the TCA cycle, and the oxidative pentose phosphate pathway to obtain NADPH.

  1. Rational Synthesis and Investigation of Porous Metal-Organic Framework Materials from a Preorganized Heterometallic Carboxylate Building Block.

    PubMed

    Sapianik, Aleksandr A; Zorina-Tikhonova, Ekaterina N; Kiskin, Mikhail A; Samsonenko, Denis G; Kovalenko, Konstantin A; Sidorov, Alexey A; Eremenko, Igor L; Dybtsev, Danil N; Blake, Alexander J; Argent, Stephen P; Schröder, Martin; Fedin, Vladimir P

    2017-02-06

    The tetranuclear heterometallic complex [Li2Zn2(piv)6(py)2] (1, where piv(-) = pivalate and py = pyridine) has been successfully employed as a presynthesized node for the construction of four porous metal-organic frameworks (MOFs) [Li2Zn2(R-bdc)3(bpy)]·solv (2-R, R-bdc(2-); R = H, Br, NH2, NO2) by reaction with 4,4'-bipyridine (bpy) and terephthalate anionic linkers. The [Li2Zn2] node is retained in the products, representing a rare example of the rational step-by-step design of isoreticular MOFs based on complex heterometallic building units. The permanent porosity of the activated frameworks was confirmed by gas adsorption isotherm measurements (N2, CO2, CH4). Three compounds, 2-H, 2-Br, and 2-NH2 (but not 2-NO2), feature extensive hysteresis between the adsorption and desorption curves in the N2 isotherms at low pressures. The substituents R decorate the inner surface and also control the aperture of the channels, the volume of the micropores, and the overall surface area, thus affecting both the gas uptake and adsorption selectivity. The highest CO2 absorption at ambient conditions (105 cm(3)·g(-1) or 21 wt % at 273 K and 1 bar for 2-NO2) is above the average values for microporous MOFs. The photoluminescent properties of the prototypic 2-H as well as the corresponding host-guest compounds with various aromatic molecules (benzene, toluene, anisole, and nitrobenzene) were systematically investigated. We discovered a rather complex pattern in the emission response of this material depending on the wavelength of excitation as well as the nature of the guest molecules. On the basis of the crystal structure of 2-H, a mechanism for these luminescent properties is proposed and discussed.

  2. Dinuclear pyridine-4-thiolate-bridged rhodium and iridium complexes as ditopic building blocks in molecular architecture.

    PubMed

    Ferrer, Montserrat; Gómez-Bautista, Daniel; Gutiérrez, Albert; Miranda, José R; Orduña-Marco, Guillermo; Oro, Luis A; Pérez-Torrente, Jesús J; Rossell, Oriol; García-Orduña, Pilar; Lahoz, Fernando J

    2014-02-03

    A series of dinuclear pyridine-4-thiolate (4-Spy)-bridged rhodium and iridium compounds [M(μ-4-Spy)(diolef)]2 [diolef = 1,5-cyclooctadiene (cod), M = Rh (1), Ir (2); diolef = 2,5-norbornadiene (nbd), M = Rh (3)] were prepared by the reaction of Li(4-Spy) with the appropriate compound [M(μ-Cl)(diolef)]2 (M = Rh, Ir). The dinuclear compound [Rh(μ-4-Spy)(CO)(PPh3)]2 (4) was obtained by the reaction of [Rh(acac)(CO)(PPh3)] (acac = acetylacetonate) with 4-pySH. Compounds 1-4 were assessed as metalloligands in self-assembly reactions with the cis-blocked acceptors [M(cod)(NCCH3)2](BF4) [M = Rh (a), Ir (b)] and [M(H2O)2(dppp)](OTf)2 [M = Pd (c), Pt (d); dppp = 1,3-bis(diphenylphosphino)propane]. The homometallic hexanuclear metallomacrocycles [{M2(μ-4-Spy)2(cod)2}2{M(cod)}2](BF4)2 (M = Rh [(1a)2], Ir [(2b)2]) and the heterometallic hexanuclear metallomacrocycles [{Rh2(μ-4-Spy)2(cod)2}2{Ir(cod)}2](BF4)2 [(1b)2], [{Rh2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 (M' = Pd [(1c)2], Pt [(1d)2]), and [{Ir2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 (M' = Pd [(2c)2], Pt [(2d)2]) were obtained. NMR spectroscopy in combination with electrospray ionization mass spectrometry was used to elucidate the nature of the metalloligands and their respective supramolecular assemblies. Most of the synthesized species were found to be nonrigid in solution, and their fluxional behavior was studied by variable-temperature (1)H NMR spectroscopy. An X-ray diffraction study of the assemblies (1a)2 and (1d)2 revealed the formation of rectangular (9.6 Å × 6.6 Å) hexanuclear metallomacrocycles with alternating dinuclear (Rh2) and mononuclear (Rh or Pt) corners. The hexanuclear core is supported by four pyridine-4-thiolate linkers, which are bonded through the thiolate moieties to the dinuclear rhodium units, exhibiting a bent-anti arrangement, and through the peripheral pyridinic nitrogen atoms to the mononuclear corners.

  3. [Quantitative morphology of vertebral body cortical bone. Building block for noninvasive calculation of fracture threshold in osteoporosis].

    PubMed

    Ritzel, H; Amling, M; Hahn, M; Maas, R; Delling, G

    1998-04-01

    The vertebral bodies consist of two main structures, trabecular and cortical bone. The histological changes within the spine, especially in cortical bone, leading to osteoporotic fractures remain, however, poorly understood. Therefore, the complete front column of the spine was removed in 26 autopsy cases without skeletal diseases and in 11 cases with proven osteoporosis. A sagittal segment prepared through the center of all vertebral bodies was undecalcified embedded in plastic, ground to a 1-mm-thick block and stained using a modification of the von Kossa method. The analysis included measurement of the mean cortical thickness of both ventral and dorsal shell (from C3 to L5). The qualitative investigation of the structure of the cortical ring completed the analysis. The skeletally intact specimens had high cortical thickness values in the cervical spine (285 +/- 22 microns), a decrease in the thoracic spine (244 +/- 14 microns) and an increase in the lumbar spine (290 +/- 15 microns). The mean thickness of the ventral shell is in general higher than the thickness of the dorsal shell. The cortical thickness of the spine showed no gender-specific differences (P = n.s.). There was a slight decrease in the cortical thickness with age; however, this decrease and the correlation of cortical thickness to age was only significant below vertebral body T8 (r = 0.225 to 0.574; Pr < 0.05 to Pr < 0.005). Most interestingly, osteoporosis is characterized by a significant decrease in cortical thickness throughout the whole spine. This decrease in cortical thickness was more marked in the dorsal shell (P < 0.05) than in the ventral shell (ventral from C3 to T6 (P < 0.05) below T6 (P = n.s.). We therefore conclude that in osteoporosis, biomechanical competence is affected by both trabecular bone loss and decrease of cortical thickness. This suggests that, in addition to trabecular bone measurements, the cortical thickness is of special interest for diagnostic radiological

  4. Silica-Triggered Autoimmunity in Lupus-Prone Mice Blocked by Docosahexaenoic Acid Consumption

    PubMed Central

    Bates, Melissa A.; Brandenberger, Christina; Langohr, Ingeborg I.; Kumagai, Kazuyoshi; Lock, Adam L.; Harkema, Jack R.; Holian, Andrij; Pestka, James J.

    2016-01-01

    Occupational exposure to respirable crystalline silica (cSiO2, quartz) is etiologically linked to systemic lupus erythematosus (lupus) and other human autoimmune diseases (ADs). In the female NZBWF1 mouse, a widely used animal model that is genetically prone to lupus, short-term repeated intranasal exposure to cSiO2 triggers premature initiation of autoimmune responses in the lungs and kidneys. In contrast to cSiO2’s triggering action, consumption of the ω-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) prevents spontaneous onset of autoimmunity in this mouse strain. The aim of this study was to test the hypothesis that consumption of DHA will prevent cSiO2-triggered autoimmunity in the female NZBWF1 mouse. Mice (6 wk old) were fed isocaloric AIN-93G diets containing 0.0, 0.4, 1.2 or 2.4% DHA. Two wk after initiating feeding, mice were intranasally instilled with 1 mg cSiO2 once per wk for 4 wk and maintained on experimental diets for an additional 12 wk. Mice were then sacrificed and the lung, blood and kidney assessed for markers of inflammation and autoimmunity. DHA was incorporated into lung, red blood cells and kidney from diet in a concentration-dependent fashion. Dietary DHA dose-dependently suppressed cSiO2-triggered perivascular leukocyte infiltration and ectopic lymphoid tissue neogenesis in the lung. DHA consumption concurrently inhibited cSiO2–driven elevation of proinflammatory cytokines, B-cell proliferation factors, IgG and anti-dsDNA Ig in both bronchoalveolar lavage fluid and plasma. DHA’s prophylactic effects were further mirrored in reduced proteinuria and glomerulonephritis in cSiO2-treated mice. Taken together, these results reveal that DHA consumption suppresses cSiO2 triggering of autoimmunity in female NZBWF1 mice as manifested in the lung, blood and kidney. Our findings provide novel insight into how dietary modulation of the lipidome might be used to prevent or delay triggering of AD by cSiO2. Such knowledge opens the

  5. Association of the pr Peptides with Dengue Virus at Acidic pH Blocks Membrane Fusion

    SciTech Connect

    Yu, I.-M.; Holdaway, H.A.; Chipman, P.R.; Kuhn, R.J.; Rossmann, M.G.; Chen, J.; Purdue

    2010-07-27

    Flavivirus assembles into an inert particle that requires proteolytic activation by furin to enable transmission to other hosts. We previously showed that immature virus undergoes a conformational change at low pH that renders it accessible to furin (I. M. Yu, W. Zhang, H. A. Holdaway, L. Li, V. A. Kostyuchenko, P. R. Chipman, R. J. Kuhn, M. G. Rossmann, and J. Chen, Science 319:1834-1837, 2008). Here we show, using cryoelectron microscopy, that the structure of immature dengue virus at pH 6.0 is essentially the same before and after the cleavage of prM. The structure shows that after cleavage, the proteolytic product pr remains associated with the virion at acidic pH, and that furin cleavage by itself does not induce any major conformational changes. We also show by liposome cofloatation experiments that pr retention prevents membrane insertion, suggesting that pr is present on the virion in the trans-Golgi network to protect the progeny virus from fusion within the host cell.

  6. Enhanced dipicolinic acid production during the stationary phase in Bacillus subtilis by blocking acetoin synthesis.

    PubMed

    Toya, Yoshihiro; Hirasawa, Takashi; Ishikawa, Shu; Chumsakul, Onuma; Morimoto, Takuya; Liu, Shenghao; Masuda, Kenta; Kageyama, Yasushi; Ozaki, Katsuya; Ogasawara, Naotake; Shimizu, Hiroshi

    2015-01-01

    Bacterial bio-production during the stationary phase is expected to lead to a high target yield because the cells do not consume the substrate for growth. Bacillus subtilis is widely used for bio-production, but little is known about the metabolism during the stationary phase. In this study, we focused on the dipicolinic acid (DPA) production by B. subtilis and investigated the metabolism. We found that DPA production competes with acetoin synthesis and that acetoin synthesis genes (alsSD) deletion increases DPA productivity by 1.4-fold. The mutant showed interesting features where the glucose uptake was inhibited, whereas the cell density increased by approximately 50%, resulting in similar volumetric glucose consumption to that of the parental strain. The metabolic profiles revealed accumulation of pyruvate, acetyl-CoA, and the TCA cycle intermediates in the alsSD mutant. Our results indicate that alsSD-deleted B. subtilis has potential as an effective host for stationary-phase production of compounds synthesized from these intermediates.

  7. Waking action of ursodeoxycholic acid (UDCA) involves histamine and GABAA receptor block.

    PubMed

    Yanovsky, Yevgenij; Schubring, Stephan R; Yao, Quiaoling; Zhao, Yan; Li, Sha; May, Andrea; Haas, Helmut L; Lin, Jian-Sheng; Sergeeva, Olga A

    2012-01-01

    Since ancient times ursodeoxycholic acid (UDCA), a constituent of bile, is used against gallstone formation and cholestasis. A neuroprotective action of UDCA was demonstrated recently in models of Alzheimer's disease and retinal degeneration. The mechanisms of UDCA action in the nervous system are poorly understood. We show now that UDCA promotes wakefulness during the active period of the day, lacking this activity in histamine-deficient mice. In cultured hypothalamic neurons UDCA did not affect firing rate but synchronized the firing, an effect abolished by the GABA(A)R antagonist gabazine. In histaminergic neurons recorded in slices UDCA reduced amplitude and duration of spontaneous and evoked IPSCs. In acutely isolated histaminergic neurons UDCA inhibited GABA-evoked currents and sIPSCs starting at 10 µM (IC(50) = 70 µM) and did not affect NMDA- and AMPA-receptor mediated currents at 100 µM. Recombinant GABA(A) receptors composed of α1, β1-3 and γ2L subunits expressed in HEK293 cells displayed a sensitivity to UDCA similar to that of native GABA(A) receptors. The mutation α1V256S, known to reduce the inhibitory action of pregnenolone sulphate, reduced the potency of UDCA. The mutation α1Q241L, which abolishes GABA(A)R potentiation by several neurosteroids, had no effect on GABA(A)R inhibition by UDCA. In conclusion, UDCA enhances alertness through disinhibition, at least partially of the histaminergic system via GABA(A) receptors.

  8. Efficient and Scalable Synthesis of 4-Carboxy-Pennsylvania Green Methyl Ester: A Hydrophobic Building Block for Fluorescent Molecular Probes.

    PubMed

    Woydziak, Zachary R; Fu, Liqiang; Peterson, Blake R

    2014-01-01

    Fluorinated fluorophores are valuable tools for studies of biological systems. However, amine-reactive single-isomer derivatives of these compounds are often very expensive. To provide an inexpensive alternative, we report a practical synthesis of 4-carboxy-Pennsylvania Green methyl ester. Derivatives of this hydrophobic fluorinated fluorophore, a hybrid of the dyes Oregon Green and Tokyo Green, are often cell permeable, enabling labeling of intracellular targets and components. Moreover, the low pKa of Pennsylvania Green (4.8) confers bright fluorescence in acidic cellular compartments such as endosomes, enhancing its utility for chemical biology investigations. To improve access to the key intermediate 2,7-difluoro-3,6-dihydroxyxanthen-9-one, we subjected bis-(2,4,5-trifluorophenyl)methanone to iterative nucleophilic aromatic substitution by hydroxide on scales of > 40 g. This intermediate was used to prepare over 15 grams of pure 4-carboxy-Pennsylvania Green methyl ester in 28% overall yield without requiring chromatography. This compound can be converted into the amine reactive N-hydroxysuccinimidyl ester in essentially quantitative yield for the synthesis of a wide variety of fluorescent molecular probes.

  9. Water-soluble organo-building blocks of aminoclay as a soil-flushing agent for heavy metal contaminated soil.

    PubMed

    Lee, Young-Chul; Kim, Eun Jung; Ko, Dong Ah; Yang, Ji-Won

    2011-11-30

    We demonstrated that water-soluble aminopropyl magnesium functionalized phyllosilicate could be used as a soil-flushing agent for heavy metal contaminated soils. Soil flushing has been an attractive means to remediate heavy metal contamination because it is less disruptive to the soil environment after the treatment was performed. However, development of efficient and non-toxic soil-flushing agents is still required. We have synthesized aminoclays with three different central metal ions such as magnesium, aluminum, and ferric ions and investigated applicability of aminoclays as soil flushing agents. Among them, magnesium (Mg)-centered aminoclay showed the smallest size distribution and superior water solubility, up to 100mg/mL. Mg aminoclay exhibited cadmium and lead binding capacity of 26.50 and 91.31 mg/g of Mg clay, respectively, at near neutral pH, but it showed negligible binding affinity to metals in acidic conditions. For soil flushing with Mg clay at neutral pH showed cadmium and lead were efficiently extracted from soils by Mg clay, suggesting strong binding ability of Mg clay with cadmium and lead. As the organic matter and clay compositions increased in the soil, the removal efficiency by Mg clay decreased and the operation time increased.

  10. Block ionomer complex micelles based on the self-assembly of poly(ethylene glycol)-block-poly(acrylic acid) and CdCl₂ for anti-tumor drug delivery.

    PubMed

    An, Liping; Wang, Yapei; Liu, Xiaomei; Ma, Ning; Du, Haiying; Jin, Minghua; Liu, Ying; Zhang, Long; Xu, Yanling; Huang, Peili; Sun, Zhiwei

    2011-01-01

    A novel block ionomer complex micelles as drug carrier is developed utilizing self-assemble of poly(ethylene glycol)-block-poly(acrylic acid) (PEG-b-PAA) and cadmium chloride. This micelles are characterized to be have good bio-compatibility, hydrophilicity, passive targeting and sustained slow release property which shows great potential for liver cancer therapy. Block ionomer complex micelles based on PEG-b-PAA and cadmium chloride can self-assemble in distilled water, and Cd(²+) agent is entrapped into the core stabilized by PEG shells. Results showed the block ionomer complex micelles to be spherically shaped. Cadmium was incorporated easily into the ionic core with remarkably high efficiency (34.25% weight (wt)/wt). The cadmium-loaded polymeric micelles exhibited sustained and slow release behavior of cadmium and a potent cytotoxicity against SMMC-7721 in vitro. This novel block ionomer complex micelles with cores of metal antitumor drug indicates to be potential carriers for effective drug delivery.

  11. Inactivation of SAG E3 ubiquitin ligase blocks embryonic stem cell differentiation and sensitizes leukemia cells to retinoid acid.

    PubMed

    Tan, Mingjia; Li, Yun; Yang, Ruiguo; Xi, Ning; Sun, Yi

    2011-01-01

    Sensitive to Apoptosis Gene (SAG), also known as RBX2 (RING box protein-2), is the RING component of SCF (SKP1, Cullin, and F-box protein) E3 ubiquitin ligase. Our previous studies have demonstrated that SAG is an anti-apoptotic protein and an attractive anti-cancer target. We also found recently that Sag knockout sensitized mouse embryonic stem cells (mES) to radiation and blocked mES cells to undergo endothelial differentiation. Here, we reported that compared to wild-type mES cells, the Sag(-/-) mES cells were much more sensitive to all-trans retinoic acid (RA)-induced suppression of cell proliferation and survival. While wild-type mES cells underwent differentiation upon exposure to RA, Sag(-/-) mES cells were induced to death via apoptosis instead. The cell fate change, reflected by cellular stiffness, can be detected as early as 12 hrs post RA exposure by AFM (Atomic Force Microscopy). We then extended this novel finding to RA differentiation therapy of leukemia, in which the resistance often develops, by testing our hypothesis that SAG inhibition would sensitize leukemia to RA. Indeed, we found a direct correlation between SAG overexpression and RA resistance in multiple leukemia lines. By using MLN4924, a small molecule inhibitor of NEDD8-Activating Enzyme (NAE), that inactivates SAG-SCF E3 ligase by blocking cullin neddylation, we were able to sensitize two otherwise resistant leukemia cell lines, HL-60 and KG-1 to RA. Mechanistically, RA sensitization by MLN4924 was mediated via enhanced apoptosis, likely through accumulation of pro-apoptotic proteins NOXA and c-JUN, two well-known substrates of SAG-SCF E3 ligase. Taken together, our study provides the proof-of-concept evidence for effective treatment of leukemia patients by RA-MLN4924 combination.

  12. Comparison of nutritional compositions and antioxidant activities of building blocks in shinseoncho and kale green vegetable juices.

    PubMed

    Kim, Seong Yeong

    2012-12-01

    Shinseoncho and kale were divided into stem [shinseoncho stems (SS) and kale stems (KS)] and leaf parts [shinseoncho leaves (SL) and kale leaves (KL)] and made into green vegetable juices for analyses of nutritional compositions and antioxidant activities. Higher values of total acidity were observed in SL (0.736%) and KL (0.841%) than in SS (0.417%) and KS (0.335%) (p<0.05). Neutral sugar content showed higher values in SS (21.740 mg/mL) and SL (18.657 mg/mL) when compared with KS (1.497 mg/mL) and KL (1.452 mg/mL) (p<0.05). Protein content showed the highest value in SL (7.610 mg/mL) (p<0.05), while SS (0.403 mg/mL) and KS (0.403 mg/mL) showed similar lower values. Total polyphenol contents of SL (423.139 μg/mL) was significantly higher value (p<0.05) than those of other samples, which occurred in the following order: SL> KL (218.494 μg/mL)> KS (107.269 μg/mL)> SS (75.894 μg/mL). KL exerted the highest DPPH radical scavenging activity (84.834%) (p<0.05), which occurred in the following order: KL> SL (63.473%)> KS (52.894%)> SS (35.443%). ABTS radical scavenging activity showed that SL (66.088%) and KL (38.511%) had higher scavenging activities, whereas SS (7.695%) and KS (9.609%) demonstrated to be lower activities (p<0.05). In general, leaf parts had much higher antioxidant activities as well as total polyphenol contents than those of the stem parts. In conclusion, shinseoncho and kale, particularly their leaf parts, offer antioxidant properties in green vegetable juices and the consumption of them may be beneficial as a nutrition source and in health protection.

  13. Selective activation/coupling of polyhalogenated nucleophiles in ni/cr-mediated reactions: synthesis of c1-c19 building block of halichondrin bs.

    PubMed

    Yan, Wuming; Li, Zhanjie; Kishi, Yoshito

    2015-05-20

    The C1-C19 building block 46 of halichondrin Bs was synthesized via a selective activation/coupling of β-bromoenone 34 with aldehyde 35 in a Ni/Cr-mediated reaction. The first phase of study was a method development to effect a coupling of a "naked" vinylogous anion with an aldehyde. The study with the coupling of 9 + 10 → 11 revealed: (1) β-bromoenone 9b is a better nucleophile than the corresponding β-iodo- and β-chloroenones 9a,c; (2) (Me)2Phen(OMe)2·NiCl2 13b is a better Ni-catalyst than (Me)2Phen(H)2·NiCl2 13a; and (3) a low Ni-catalyst loading, for example, 0.05-0.1 mol % Ni-catalyst against 10 mol % Cr-catalyst, is crucial for an effective coupling. The second phase of study was a method development to realize a selective activation/coupling of polyhalogenated nucleophiles such as 34. The competition experiment of 10 + 9b over 10 + 31a-c revealed: (1) (Me)2Phen(OMe)2·NiCl2 13b is more effective than (Me)2Phen(H)2·NiCl2 13a for the required selective activation/coupling; (2) a low Ni-catalyst loading, for example, 0.05-0.1 mol % Ni-catalyst against 10 mol % Cr-catalyst, is crucial for discriminating β-bromoenone 9b from the three types of vinyl iodides 31a-c. The third phase of study was an application of the developed method to execute the proposed coupling of 34 + 35 → 36. For this application, a polyether-type Ni-catalyst 37c, readily soluble in the reaction medium, was introduced to achieve the selective activation/coupling with higher efficiency. With use of ion-exchange resin-based device, the coupling product 36 was transformed to the C1-C19 building block 46 of halichondrin Bs without purification/separation of the intermediates.

  14. Constructing high-efficiency D-A-π-A-featured solar cell sensitizers: a promising building block of 2,3-diphenylquinoxaline for antiaggregation and photostability.

    PubMed

    Pei, Kai; Wu, Yongzhen; Islam, Ashraful; Zhang, Qiong; Han, Liyuan; Tian, He; Zhu, Weihong

    2013-06-12

    Controlling the sensitizer morphology on a nanocrystalline TiO2 surface is beneficial to facilitating electron injection and suppressing charge recombination. Given that the grafted alkyl chain on a π-bridge thiophene segment for preventing π aggregation can deteriorate its intrinsic photostability, we incorporate a promising building block of 2,3-diphenylquinoxaline as the additional acceptor to construct a novel D-A-π-A-featured dye IQ4, which exhibits several characteristics: (i) efficiently decreasing the molecular HOMO-LUMO energy gap by extending its absorption bands; (ii) showing a moderate electron-withdrawing capability for an ideal balance in both promising photocurrent and photovoltage; (iii) endowing an ideal morphology control with strong capability of restraining the intermolecular aggregation and facilitating the formation of a compact sensitizer layer via two twisted phenyl groups grafted onto the quinoxaline unit. The coadsorbent-free dye-sensitized solar cell (DSSC) based on dye IQ4 exhibits very promising conversion efficiency as high as 9.24 ± 0.05%, with a short-circuit current density (Jsc) of 17.55 mA cm(-2), an open-circuit voltage (Voc) of 0.74 V, and a fill factor (FF) of 0.71 under AM 1.5 illumination (100 mW cm(-2)). IQ4-based DSSC devices with an ionic liquid electrolyte can keep constant performance during a 1000 h aging test under 1 sun at 60 °C. Because of spatial restriction, the two phenyl groups grafted onto the additional electron-withdrawing quinoxaline are demonstrated as efficient building blocks, not only improving its photostability and thermal stability but also allowing it to be a successful antiaggregation functional unit. As a consequence, the incorporated 2,3-diphenylquinoxaline unit can realize a facile structural modification for constructing organic coadsorbent-free D-A-π-A-featured sensitizers, thus paving a way to replace the common, stability-deleterious grafted alkyl chain on the thienyl bridge.

  15. Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s bearing functionalizable carbonate building blocks: II. Enzymatic biodegradation and in vitro biocompatibility assay.

    PubMed

    Yang, Jing; Tian, Weisheng; Li, Qiaobo; Li, Yang; Cao, Amin

    2004-01-01

    In a previous study, we have reported chemical synthesis of novel aliphatic poly(butylene succinate-co-cyclic carbonate) P(BS-co-CC)s bearing various functionalizable carbonate building blocks, and this work will continue to present our new studies on their enzymatic degradation and in vitro cell biocompatibility assay. First, enzymatic degradation of the novel P(BS-co-CC) film samples was investigated with two enzymes of lipase B Candida Antartic (Novozyme 435) and lipase Porcine Pancreas PPL, and it was revealed that copolymerizing linear poly(butylene succinate) PBS with a functionalizable carbonate building block could remarkably accelerate the enzymatic degradation of a synthesized product P(BS-co-CC), and its biodegradation behavior was found to strongly depend on the overall impacts of several important factors as the cyclic carbonate (CC) comonomer structure and molar content, molar mass, thermal characteristics, morphology, the enzyme-substrate specificity, and so forth. Further, the biodegraded residual film samples and water-soluble enzymatic degradation products were allowed to be analyzed by means of proton nuclear magnetic resonance (1H NMR), gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), attenuated total reflection FTIR (ATR-FTIR), scanning electron microscope (SEM), and liquid chromatograph-mass spectrometry (LC-MS). On the experimental evidences, an exo-type mechanism of enzymatic chain hydrolysis preferentially occurring in the noncrystalline domains was suggested for the synthesized new P(BS-co-CC) film samples. With regard to their cell biocompatibilities, an assay with NIH 3T3 mouse fibroblast cell was conducted using the novel synthesized P(BS-co-CC) films as substrates with respect to the cell adhesion and proliferation, and these new biodegradable P(BS-co-CC) samples were found to exhibit as low cell toxicity as the PLLA control, particularly the two samples of poly(butylene succinate-co-18.7 mol % dimethyl

  16. Rational design of hierarchical ZnO superstructures for efficient charge transfer: mechanistic and photovoltaic studies of hollow, mesoporous, cage-like nanostructures with compacted 1D building blocks.

    PubMed

    Chetia, Tridip Ranjan; Ansari, Mohammad Shaad; Qureshi, Mohammad

    2016-02-21

    Mesoporous and hollow zinc oxide (ZnO) hierarchical superstructures assembled with compact 1D building blocks that provide an efficient and faster transport pathway for photo-generated charge carriers have been synthesized using a biomass derived polysaccharide "alginic acid". To understand the interactions between the organic bio-template and inorganic growth units of ZnO in aqueous medium, the effects of additives such as the alginate ion (ALGI) and ammonium hydroxide (NH4OH), along with the controlled reaction conditions, are investigated using Field Emission Scanning Electron Microscopy (FESEM) and powder X-ray diffraction. Dynamic and steady-state photoluminescence measurements are carried out to understand the charge transfer processes in the compact 1D superstructures. Experimental analyses reveal that the alginate ions, under hydrothermal reaction conditions, act as a structure directing agent and assemble 1D ZnO nanorods (NRs) hierarchically while NH4OH assists the formation of ZnO growth units. A plausible mechanism for ZnO cage formation is proposed based on the experimental observations. Morphology dependent photovoltaic properties of ZnO heterostructures, i.e., for ZnO cages, ZnO NRs and ZnO PNPs, have been studied along with electrochemical impedance spectroscopy (EIS). Enhancement of ∼ 60% and ∼ 35% in power conversion efficiency (PCE) is observed in ZnO cage based devices as compared to ZnO NR- and ZnO PNP-based devices, respectively.

  17. Zinc(II) and lead(II) metal-organic networks driven by a multifunctional pyridine-carboxylate building block: Hydrothermal synthesis, structural and topological features, and luminescence properties

    NASA Astrophysics Data System (ADS)

    Yang, Ling; Li, Yu; You, Ao; Jiang, Juan; Zou, Xun-Zhong; Chen, Jin-Wei; Gu, Jin-Zhong; Kirillov, Alexander M.

    2016-09-01

    4-(5-Carboxypyridin-2-yl)isophthalic acid (H3L) was applied as a flexible, multifunctional N,O-building block for the hydrothermal self-assembly synthesis of two novel coordination compounds, namely 2D [Zn(μ3-HL)(H2O)]n·nH2O (1) and 3D [Pb2(μ5-HL)(μ6-HL)]n (2) coordination polymers (CPs). These compounds were obtained in aqueous medium from a mixture containing zinc(II) or lead(II) nitrate, H3L, and sodium hydroxide. The products were isolated as stable crystalline solids and were characterized by IR spectroscopy, elemental, thermogravimetric (TGA), powder (PXRD) and single-crystal X-ray diffraction analyses. Compound 1 possesses a 2D metal-organic layer with the fes topology, which is further extended into a 3D supramolecular framework via hydrogen bonds. In contrast, compound 2 features a very complex network structure, which was topologically classified as a binodal 5,6-connected net with the unique topology defined by the point symbol of (47.63)(49.66). Compounds 1 and 2 disclose an intense blue or green luminescent emission at room temperature.

  18. Spontaneous self-assembly of a giant spherical metal-oxide Keplerate: addition of one building block induces "immediate" formation of the complementary one from a constitutional dynamic library.

    PubMed

    Schäffer, Christian; Todea, Ana Maria; Gouzerh, Pierre; Müller, Achim

    2012-01-11

    The addition of dinuclear {Mo(2)} units to a dynamic library containing molybdates results in the spontaneous self-assembly of a giant spherical metal-oxide species of the type {(Mo)Mo(5)}(12){Mo(2)}(30) while the required pentagonal {(Mo)Mo(5)} building blocks are "immediately" formed.

  19. Zeolitic polyoxometalates metal organic frameworks (Z-POMOF) with imidazole ligands and epsilon-Keggin ions as building blocks; computational evaluation of hypothetical polymorphs and a synthesis approach.

    PubMed

    Rodriguez Albelo, L Marleny; Ruiz-Salvador, A Rabdel; Lewis, Dewi W; Gómez, Ariel; Mialane, Pierre; Marrot, Jérome; Dolbecq, Anne; Sampieri, Alvaro; Mellot-Draznieks, Caroline

    2010-08-14

    We investigate here a new family of zeolitic Metal Organic Frameworks (MOFs) based on imidazole (im) as the ligand and epsilon-type Keggin PolyOxoMetalates (POMs) as building units. The POM used in this study is the epsilon-{PMo(12)O(40)} Keggin isomer capped by four Zn(ii) ions (noted epsilon-Zn) in tetrahedral coordination. We describe here our methods to first construct and then evaluate the stability of hypothetical 3-D POMOFs possessing a tetrahedral network, typified by dense silica polymorphs and zeotypes and referred here to as Z-POMOFs. We use the analogy between the connectivity of silicon ion in dense minerals or zeolites and the epsilon-Zn, using imidazolate ligands to mimic the role of oxygen atoms in zeolites. Handling the epsilon-Keggin and imidazole as the constitutive building-blocks, a selection of 40 polymorphs were constructed and their relative stabilities computed. Among these Z-POMOFs, the cristobalite-like and zni-structure were identified as the most stable candidates. In parallel, we have attempted to synthesize Z-POMOF structures with epsilon-Zn POMs, synthesized in situ under hydrothermal conditions, and imidazole ligands. We present our first experimental result, the extended material [NBu(4)][PMo(V)(8)Mo(VI)(4)O(37)(OH)(3)Zn(4)(im)(Him)], named epsilon(im)(2). The structure of the hybrid framework is built by the connection of dimerized epsilon-Zn POMs to imidazole ligands in two directions. The obtaining of the first POMOF based on imidazole ligand is an encouraging step towards the synthesis of a new family of POMOFs.

  20. Poly(acrylic acid)-block-poly(vinyl alcohol) anchored maghemite nanoparticles designed for multi-stimuli triggered drug release

    NASA Astrophysics Data System (ADS)

    Liu, Ji; Detrembleur, Christophe; Debuigne, Antoine; de Pauw-Gillet, Marie-Claire; Mornet, Stéphane; Vander Elst, Luce; Laurent, Sophie; Labrugère, Christine; Duguet, Etienne; Jérôme, Christine

    2013-11-01

    Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene blue (MB), a cationic model drug. The triggered release of MB was studied under various stimuli such as pH, ionic strength and temperature. Local heating generated under alternating magnetic field (AMF) application was studied, and remotely AMF-triggered release was also confirmed, while a mild heating-up of the release medium was observed. Furthermore, their potential application as magnetic resonance imaging (MRI) contrast agents was explored via relaxivity measurements and acquisition of T2-weighted images. Preliminary studies on the cytotoxicity against mouse fibroblast-like L929 cell line and also their cellular uptake within human melanoma MEL-5 cell line were carried out. In conclusion, this kind of stimuli-responsive nanoparticles appears to be promising carriers for delivering drugs to some tumour sites or into cellular compartments with an acidic environment.Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene