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Sample records for achiral building blocks

  1. 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)

  2. Spintronics: Conceptual Building Blocks

    NASA Astrophysics Data System (ADS)

    Ansermet, J.-Ph.

    The purpose of this introduction to spintronics is to provide some elementary description of its conceptual building blocks. Thus, it is intended for a newcomer to the field. After recalling rudimentary descriptions of spin precession and spin relaxation, spin-dependent transport is treated within the Boltzmann formalism. This suffices to introduce key notions such as the spin asymmetry of the conductivities in the two-current model, the spin diffusion length, and spin accumulation. Two basic mechanisms of spin relaxation are then presented, one arising from spin-orbit scattering and the other from electron-magnon collisions. Finally, the action of a spin-polarized current on magnetization is presented in a thermodynamics framework. This introduces the notion of spin torque and the characteristic length scale over which the transverse spin polarization of conduction electron decays as it is injected into a magnet.

  3. 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…

  4. 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.

  5. A new chiral uranyl phosphonate framework consisting of achiral building units generated from ionothermal reaction: structure and spectroscopy characterizations.

    PubMed

    Zheng, Tao; Gao, Yang; Chen, Lanhua; Liu, Zhiyong; Diwu, Juan; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

    2015-11-01

    The ionothermal reactions of uranyl nitrate and 1,3-pbpH4 (1,3-pbpH4 = 1,3-phenylenebis(phosphonic acid) ligand in ionic liquids of [C4mim][Dbp], [C4mpyr][Br], and [Etpy][Br], respectively, afforded three new uranyl phosphonates, namely [C4mim][(UO2)2(1,3-pbpH)(1,3-pbpH)·Hmim] (1), [UO2(1,3-pbpH2)H2O·mpr] (2), and [Etpy][UO2(1,3-pbpH2)F] (3). Compound 1 exhibits a rare example of a chiral uranyl phosphonate 3D framework structure built from achiral building units of tetragonal bipyramidal uranium polyhedra and 1,3-pbp ligands. The structure adopts a network with channels extending along the b axis, which are filled with C4mim(+) and protonated 1-methylimidazole. In sharp contrast, compounds 2 & 3 both show pillared topology composed of uranyl pentagonal bipyramid polyhedra and phosphonate ligands. The layers are neutral in compound 2 with N-methylpyrrole molecules in the interlayer space, while compound 3 adopts anionic layer, and the charge is compensated with N-ethyl-pyridinium cations between the layers. Although compounds 1, 2, and 3 were synthesized under identical conditions with sole variation of the ionic liquid species, the resulting structures show a rich diversity in the local coordination environment of uranyl ions, the protonation of the phosphonate ligand, the conformation of ionic liquid ions, and the overall arrangement of the structure. All compounds were characterized by absorption, temperature dependent fluorescence, as well as infrared and Raman spectroscopies. PMID:26419426

  6. Spin-torque building blocks.

    PubMed

    Locatelli, N; Cros, V; Grollier, J

    2014-01-01

    The discovery of the spin-torque effect has made magnetic nanodevices realistic candidates for active elements of memory devices and applications. Magnetoresistive effects allow the read-out of increasingly small magnetic bits, and the spin torque provides an efficient tool to manipulate - precisely, rapidly and at low energy cost - the magnetic state, which is in turn the central information medium of spintronic devices. By keeping the same magnetic stack, but by tuning a device's shape and bias conditions, the spin torque can be engineered to build a variety of advanced magnetic nanodevices. Here we show that by assembling these nanodevices as building blocks with different functionalities, novel types of computing architecture can be envisaged. We focus in particular on recent concepts such as magnonics and spintronic neural networks. PMID:24343514

  7. Spin-torque building blocks

    NASA Astrophysics Data System (ADS)

    Locatelli, N.; Cros, V.; Grollier, J.

    2014-01-01

    The discovery of the spin-torque effect has made magnetic nanodevices realistic candidates for active elements of memory devices and applications. Magnetoresistive effects allow the read-out of increasingly small magnetic bits, and the spin torque provides an efficient tool to manipulate -- precisely, rapidly and at low energy cost -- the magnetic state, which is in turn the central information medium of spintronic devices. By keeping the same magnetic stack, but by tuning a device's shape and bias conditions, the spin torque can be engineered to build a variety of advanced magnetic nanodevices. Here we show that by assembling these nanodevices as building blocks with different functionalities, novel types of computing architecture can be envisaged. We focus in particular on recent concepts such as magnonics and spintronic neural networks.

  8. Dynamic Covalent Nanoparticle Building Blocks.

    PubMed

    Kay, Euan R

    2016-07-25

    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

  9. The building blocks of magnonics

    NASA Astrophysics Data System (ADS)

    Lenk, B.; Ulrichs, H.; Garbs, F.; Münzenberg, M.

    2011-10-01

    Novel material properties can be realized by designing waves’ dispersion relations in artificial crystals. The crystal’s structural length scales may range from nano- (light) up to centimeters (sound waves). Because of their emergent properties these materials are called metamaterials. Different to photonics, where the dielectric constant dominantly determines the index of refraction, in a ferromagnet the spin-wave index of refraction can be dramatically changed already by the magnetization direction. This allows a different flexibility in realizing dynamic wave guides or spin-wave switches. The present review will give an introduction into the novel functionalities of spin-wave devices, concepts for spin-wave based computing and magnonic crystals. The parameters of the magnetic metamaterials are adjusted to the spin-wave k-vector such that the magnonic band structure is designed. However, already the elementary building block of an antidot lattice, the singular hole, owns a strongly varying internal potential determined by its magnetic dipole field and a localization of spin-wave modes. Photo-magnonics reveal a way to investigate the control over the interplay between localization and delocalization of the spin-wave modes using femtosecond lasers, which is a major focus of this review. We will discuss the crucial parameters to realize free Bloch states and how, by contrast, a controlled localization might allow us to gradually turn on and manipulate spin-wave interactions in spin-wave based devices in the future.

  10. Building Trades. Block II. Foundations.

    ERIC Educational Resources Information Center

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

    Twelve informational lessons and eleven manipulative lessons are provided on foundations as applied to the building trades. Informational lessons cover land measurements; blueprint reading; level instruments; building and site planning; building site preparation; laying out building lines; soil preparation and special evacuation; concrete forms;…

  11. 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

  12. A Scholarly Article about Block Building.

    ERIC Educational Resources Information Center

    Kelly, Keith

    This paper provides a brief literature review on the use of building blocks in the elementary school classroom and discusses classroom activities using blocks as they influence other subject areas. The paper includes work activities that develop mathematics and science skills, language arts and reading, and social sciences. Comments on these…

  13. "Building Blocks" for Early Childhood Mathematics

    ERIC Educational Resources Information Center

    Sarama, Julie; Clements, Douglas H.

    2004-01-01

    Building Blocks is a National Science Foundation-funded project designed to enable all young children to build a solid foundation for mathematics. To ensure this, we used a design and development model that drew from theory and research in each phase. Our design process is based on the assumption that curriculum and software design can and should…

  14. 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.

  15. 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 success in…

  16. 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.

  17. Building Blocks of Tropical Diabatic Heating

    SciTech Connect

    Hagos, Samson M.

    2010-07-01

    Rotated EOF analyses are used to study the composition and variability of large-scale tropical diabatic heating profiles estimated from eight field campaigns. The results show that the profiles are composed of a pair of building blocks. These are the stratiform heating with peak heating near 400hpa and a cooling peak near 700hPa and convective heating with a heating maximum near 700hPa. Variations in the contributions of these building blocks account for the evolution of the large-scale heating profile. Instantaneous top (bottom) heavy large scale heating profiles associated with excess of stratiform (convective) heating evolve towards a stationary mean profile due to exponential decay of the excess stratiform (convective) heating.

  18. Self Assembly of Complex Building Blocks

    NASA Astrophysics Data System (ADS)

    Stucke, David; Crespi, Vincent

    2004-03-01

    A genetic search algorithm for optimizing the packing density of self-assembled multicomponent crystals of nanoparticles applied to complex colloidal building blocks will be presented. The algorithm searches the complex multi-dimensional space to find preferred crystal structures where standard methods fail. Mixtures of colloidal molecules and the structures found to be preferred to phase separation for different species of coloidal molecule mixtures will be shown.

  19. Building blocks for correlated superconductors and magnets

    SciTech Connect

    Sarrao, J. L.; Ronning, F.; Bauer, E. D.; Batista, C. D.; Zhu, J. -X.; Thompson, J. 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. A building block for hardware belief networks.

    PubMed

    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

  1. 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

  2. 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

  3. Nanoscale Building Blocks and Nanoassembly of Structures

    NASA Astrophysics Data System (ADS)

    Ozkan, Cengiz

    2003-03-01

    Electronics and photonics industries are highly interested in developing new methods for nanofabrication in order to be able to continue their long-term trend of building ever smaller, faster and less expensive devices. Conventional patterning strategies must be augmented by new techniques in order to truly take advantage of the quantum nature of novel nanoscale devices. In our research, we are developing a bottom-up approach to fabricate building blocks, which can be used to assemble nanostructures and devices. This involves the assembly of atom- and molecule-like nanostructures into functional 2-D and 3-D units. This will take advantage of the unique optical, electronic, and size-tunable properties of nanostructures and permit the use of these properties for "real" applications in a larger system (> 10 nm and < 1 um). Here, we demonstrate a novel technique for the fabrication of nano-assemblies of carbon nanotubes (CNT) and quantum dots (QD) (CNT-QD conjugates) for the first time using a zero length cross-linker. CNT's are primarily functionalized with carboxylic end groups by oxidation in concentrated sulfuric acid. Thiol stabilized QD's in aqueous solution with amino end groups were prepared in the laboratory. The ethylene carbodiimide coupling reaction was used to achieve the CNT-QD conjugation. Sulfo-N-Hydroxysuccinimide (sulfo-NHS) was used to enhance this coupling procedure. We present EDS and FTIR data for the chemical modification and SEM images of the first nano-building blocks. Current work includes the more complex 3-D assembly of QD's and nanotubes on Anodized Aluminum Oxide (AAO) template for nanodevices. Potential future applications of our method include the fabrication of novel electronic and photonic devices, crystal displays and biosensors.

  4. 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)

  5. 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

  6. 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. PMID:25721775

  7. Building Blocks to Colorado's Content Standards: Mathematics, Reading and Writing.

    ERIC Educational Resources Information Center

    Allen-Young, Darcy; Amundson, Jane L.; Bowers, Lori Goodwin; Koehn, Jo; Triolo-Moloney, Sharon; Vendegna, Nan; Peterson, Sandra

    The Building Blocks to Colorado's Content Standards were developed to connect early childhood education to the K-12 content standards, to advocate for appropriate teaching strategies for preschool children, and to support awareness and understanding of early childhood foundational skills among parents and teachers. Five sets of building blocks are…

  8. 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)

  9. 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

    2016-03-01

    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. PMID:26689976

  10. 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

  11. 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).

  12. 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...

  13. Dodecaamide cages: organic 12-arm building blocks for supramolecular chemistry.

    PubMed

    Culshaw, Jamie L; Cheng, Ge; Schmidtmann, Marc; Hasell, Tom; Liu, Ming; Adams, Dave J; Cooper, Andrew I

    2013-07-10

    A simple, one-step amidation reaction is used to produce a range of 12-arm organic building blocks for supramolecular chemistry via the derivatization of porous imine cages. As an example, microporous dendrimers are prepared. PMID:23786167

  14. A building block approach to security at shipping ports

    NASA Astrophysics Data System (ADS)

    Huck, Robert C.; Al-Akkoumi, Mouhammad K.; Shammaa, Samer; Sluss, James J., Jr.; Radhakrishnan, Sridhar; Landers, Thomas L.

    2009-09-01

    With over 360 ports of entry and 20 million sea, truck, and rail containers entering the United States every year, port facilities pose a large risk to security. Securing these ports and monitoring the variety of traffic that enter and leave is a major task. To accomplish this, the authors propose a fully distributed building block approach to port security. Based on prior work accomplished in the design and fielding of an intelligent transportation system in the United States, building blocks can be assembled, mixed and matched, and scaled to provide a comprehensive security system. Network blocks, surveillance blocks, sensor blocks, and display blocks will be developed and demonstrated in the lab, and at an inland port. The following functions will be demonstrated and scaled through analysis and demonstration: Barge tracking, credential checking, container inventory, vehicle tracking, and situational awareness. The concept behind this research is "any operator on any console can control any device at any time."

  15. 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.

  16. Big Questions: The Ultimate Building Blocks of Matter

    ScienceCinema

    Lincoln, Don

    2014-08-07

    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.

  17. Strategies for Controlled Placement of Nanoscale Building Blocks

    PubMed Central

    2007-01-01

    The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others. PMID:21794185

  18. Automate Your Physical Plant Using the Building Block Approach.

    ERIC Educational Resources Information Center

    Michaelson, Matt

    1998-01-01

    Illustrates how Mount Saint Vincent University (Halifax), by upgrading the control and monitoring of one building or section of the school at a time, could produce savings in energy and operating costs and improve the environment. Explains a gradual, "building block" approach to facility automation that provides flexibility without a heavy…

  19. 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;…

  20. Designing a Nanotube Using Naturally Occurring Protein Building Blocks

    PubMed Central

    Tsai, Chung-Jung; Zheng, Jie; Nussinov, Ruth

    2006-01-01

    Here our goal is to carry out nanotube design using naturally occurring protein building blocks. Inspection of the protein structural database reveals the richness of the conformations of proteins, their parts, and their chemistry. Given target functional protein nanotube geometry, our strategy involves scanning a library of candidate building blocks, combinatorially assembling them into the shape and testing its stability. Since self-assembly takes place on time scales not affordable for computations, here we propose a strategy for the very first step in protein nanotube design: we map the candidate building blocks onto a planar sheet and wrap the sheet around a cylinder with the target dimensions. We provide examples of three nanotubes, two peptide and one protein, in atomistic model detail for which there are experimental data. The nanotube models can be used to verify a nanostructure observed by low-resolution experiments, and to study the mechanism of tube formation. PMID:16683021

  1. Functionalised Clathrochelate Complexes--New Building Blocks for Supramolecular Structures.

    PubMed

    Wise, Matthew D; Severin, Kay

    2015-01-01

    Tris(dioxime) iron(II) clathrochelate complexes functionalised with 3- and 4-pyridyl groups have been employed as building blocks in the preparation of supramolecular structures by coordination-driven self-assembly. These complexes possess a number of desirable characteristics, being straightforward to synthesise and offering ample opportunity for steric and functional modification. Clathrochelate-based 4,4'-bipyridyl metalloligands from 1.5 nm to 5.4 nm in length were prepared in up to two steps and their potential as building blocks for supramolecular architectures demonstrated through the preparation of a discrete molecular square and a three dimensional (3D) coordination polymer. Furthermore, the structure-directing capability of clathrochelate building blocks was illustrated through the synthesis of octahedral cage compounds, which are capable of encapsulating the large, hydrophobic BPh4- anion in aqueous solvent mixtures. PMID:26668936

  2. Synthesis of glycolipopeptidic building blocks for carbohydrate receptor discovery.

    PubMed

    Ziora, Zyta M; Wimmer, Norbert; New, Roger; Skwarczynski, Mariusz; Toth, Istvan

    2011-09-01

    A class of glycolipopeptides for use as building blocks for a new type of dynamic combinatorial library is reported. The members of the library consist of a variable carbohydrate moiety, coded amino acids, and lipoamino acids in order to convert them into amphiphiles. Glycolipopeptidic amphiphiles interact through non-covalent bonding when mixed together in aqueous phase and form micelles in dynamic close-packed fluid mosaic arrays. The head groups of amphiphiles are exposed on the micelle surface, providing entities which could be screened in biological assays to find the most potent combination of building blocks in order to identify new bioactive carbohydrate ligands. PMID:21641587

  3. 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.

  4. 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…

  5. 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.

  6. 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. PMID:27586929

  7. 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…

  8. 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

  9. Building blocks for measuring care coordination with claims data.

    PubMed

    Segal, Jodi B; DuGoff, Eva H

    2014-08-01

    Tools to measure care coordination are needed to evaluate federal, state, and private sector efforts encouraging coordination to improve health outcomes and contain costs. Administrative data are a rich source of data for studying the use of medical services, thus allowing for measurement of patient level, provider level, and system measures of care coordination. Based on a review the literature and input from an expert panel, this article describes 4 key components-building blocks-of care coordination and corresponding measures. These building blocks should have utility across clinical conditions. They may be used to test hypotheses about the impact of coordinated care on medication utilization, adherence to medications, and clinical outcomes. PMID:24606582

  10. Discrete fracture patterns of virus shells reveal mechanical building blocks.

    PubMed

    Ivanovska, Irena L; Miranda, Roberto; Carrascosa, Jose L; Wuite, Gijs J L; Schmidt, Christoph F

    2011-08-01

    Viral shells are self-assembled protein nanocontainers with remarkable material properties. They combine simplicity of construction with toughness and complex functionality. These properties make them interesting for bionanotechnology. To date we know little about how virus structure determines assembly pathways and shell mechanics. We have here used atomic force microscopy to study structural failure of the shells of the bacteriophage Φ29. We observed rigidity patterns following the symmetry of the capsid proteins. Under prolonged force exertion, we observed fracture along well-defined lines of the 2D crystal lattice. The mechanically most stable building block of the shells was a trimer. Our approach of "reverse engineering" the virus shells thus made it possible to identify stable structural intermediates. Such stable intermediates point to a hierarchy of interactions among equal building blocks correlated with distinct next-neighbor interactions. The results also demonstrate that concepts from macroscopic materials science, such as fracture, can be usefully employed in molecular engineering. PMID:21768340

  11. Charge-Compensated Metallacarborane Building Blocks for Conjugation with Peptides.

    PubMed

    Frank, René; Ahrens, Verena M; Boehnke, Solveig; Beck-Sickinger, Annette G; Hey-Hawkins, Evamarie

    2016-02-15

    The cobalt bis(dicarbollide) complex [commo-3,3'-Co(1,2-C2 B9 H11 )2 ](-) has captured much attention in biochemical and medical contexts, in particular for the treatment of tumors by boron neutron capture therapy (BNCT). Derivatives of cobalt bis(dicarbollide) are commonly prepared through ring-opening reactions of cyclic oxonium ions, so the corresponding products are usually charged. Furthermore, attempts to incorporate cobalt bis(dicarbollide) into peptides are rare, despite obvious potential advantages. Here the synthesis of an imidazolium-based charge-compensated cobalt bis(dicarbollide) building block, which allows additional modifications with moieties of biochemical relevance, such as monosaccharides, is reported. Furthermore, conjugates of these building blocks with the Y1 -receptor-selective derivative of neuropeptide Y ([F(7) ,P(34) ]-NPY) retained excellent response to hY1 receptors found to be overexpressed in breast tumors and metastases. PMID:26662708

  12. Synthesis of Triamino Acid Building Blocks with Different Lipophilicities

    PubMed Central

    Maity, Jyotirmoy; Honcharenko, Dmytro; Strömberg, Roger

    2015-01-01

    To obtain different amino acids with varying lipophilicity and that can carry up to three positive charges we have developed a number of new triamino acid building blocks. One set of building blocks was achieved by aminoethyl extension, via reductive amination, of the side chain of ortnithine, diaminopropanoic and diaminobutanoic acid. A second set of triamino acids with the aminoethyl extension having hydrocarbon side chains was synthesized from diaminobutanoic acid. The aldehydes needed for the extension by reductive amination were synthesized from the corresponding Fmoc-L-2-amino fatty acids in two steps. Reductive amination of these compounds with Boc-L-Dab-OH gave the C4-C8 alkyl-branched triamino acids. All triamino acids were subsequently Boc-protected at the formed secondary amine to make the monomers appropriate for the N-terminus position when performing Fmoc-based solid-phase peptide synthesis. PMID:25876040

  13. Developing Building Blocks with Space Agencies: The Key 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.

  14. 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.

  15. 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

  16. Highly crystalline covalent organic frameworks from flexible building blocks.

    PubMed

    Xu, Liqian; Ding, San-Yuan; Liu, Junmin; Sun, Junliang; Wang, Wei; Zheng, Qi-Yu

    2016-03-28

    Two novel 2D covalent organic frameworks (TPT-COF-1 and TPT-COF-2) were synthesized from the flexible 2,4,6-triaryloxy-1,3,5-triazine building blocks on a gram scale, which show high crystallinity and large surface area. The controllable formation of highly ordered frameworks is mainly attributed to the self-assembly Piedfort unit of 2,4,6-triaryloxy-1,3,5-triazine. PMID:26954751

  17. 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

  18. 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, manipulatives, and print material.…

  19. 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.

  20. 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.

  1. Mg intercalation into Ti2C building block

    NASA Astrophysics Data System (ADS)

    Yu, Xue-fang; Cheng, Jianbo; Liu, Zhenbo; Li, Qingzhong; Li, Wenzuo; Yang, Xin; Xiao, Bo

    2015-06-01

    Generally, intercalation occurs when foreign atoms intercalate into multi-layer structures, while adsorption occurs when foreign atoms interact with monolayer structures or surfaces. We performed an investigation on the Mg intercalation into Ti2C building block (MXene) from first-principles simulation. We found that Mg can favorably intercalate into MXene, forming the stable compound Ti2MgC, which corresponds to the stage I in the Li intercalation into graphite. Based on the evaluation of the average cell potential and the energy barrier of Mg diffusion for the most energetically stable structure, our results suggest that Ti2MgC is a potential anode for Mg ion batteries.

  2. Versatile Route to Arylated Fluoroalkyl Bromide Building Blocks.

    PubMed

    Kaplan, Peter T; Vicic, David A

    2016-02-19

    New difunctionalized and fluoroalkylated silyl reagents have been prepared that react with silver and copper salts to afford active catalysts that can be used to synthesize arylated fluoroalkyl bromide building blocks. It has been shown that the [(phen)Ag(CF2)nBr] intermediates are capable of transferring both the phenanthroline ligand and the fluoroalkyl bromide chain to copper iodide, eliminating the need for a preligated copper salt precursor. The methodology is compatible with various chain lengths of the fluoroalkyl halide functionality. PMID:26820388

  3. Universal clusters as building blocks of stable quantum matter

    NASA Astrophysics Data System (ADS)

    Endo, Shimpei; García-García, Antonio M.; Naidon, Pascal

    2016-05-01

    We present an exploratory study that suggests that Efimov physics, a leading research theme in few-body quantum physics, can also induce stable many-body ground states whose building blocks are universal clusters. We identify a range of parameters in a mass-and-density-imbalanced two-species fermionic mixture for which the ground state is a gas of Efimov-related universal trimers. An explicit calculation of the trimer-trimer interaction reveals that the trimer phase is an SU(3) Fermi liquid stable against recombination losses. We propose to experimentally observe this phase in a fermionic 53Cr-6Li mixture.

  4. Building Blocks for Measuring Care Coordination with Claims Data

    PubMed Central

    DuGoff, Eva H.

    2014-01-01

    Abstract Tools to measure care coordination are needed to evaluate federal, state, and private sector efforts encouraging coordination to improve health outcomes and contain costs. Administrative data are a rich source of data for studying the use of medical services, thus allowing for measurement of patient level, provider level, and system measures of care coordination. Based on a review the literature and input from an expert panel, this article describes 4 key components—building blocks—of care coordination and corresponding measures. These building blocks should have utility across clinical conditions. They may be used to test hypotheses about the impact of coordinated care on medication utilization, adherence to medications, and clinical outcomes. (Population Health Management 2014;17:247–252) PMID:24606582

  5. 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.

  6. PAMAM Dendrimers as Quantized Building Blocks for Novel Nanostructures.

    PubMed

    van Dongen, Mallory A; Vaidyanathan, S; Banaszak Holl, Mark M

    2013-12-21

    The desire to synthesize soft supramolecular structures with size scales similar to biological systems has led to work in assembly of polymeric nanomaterials. Recent advances in the isolation of generationally homogenous poly(amidoamine) (PAMAM) dendrimer enables their use as quantized building blocks. Here, we report their assembly into precise nanoclusters. In this work, click-functional ligands are stochastically conjugated to monomeric generation 5 PAMAM dendrimer and separated via reverse-phase HPLC to isolate dendrimers with precise numbers of click ligands per dendrimer particle. The click-ligand/dendrimer conjugates are then employed as modular building blocks for the synthesis of defined nanostructures. Complimentary click chemistry employing dendrimers with 1, 2, 3, or 4 ring-strained cyclooctyne ligands and dendrimers with 1 azide ligand were utilized to prepare megamer structures containing 2 to 5 ~30,000 kDa monomer units as characterized by mass spectrometry, size exclusion chromatography, and reverse-phase liquid chromatography. The resulting structures are flexible with masses ranging from 60,000 to 150,000 kDa, and are soluble in water, methanol, and dimethylsulfoxide. PMID:24319491

  7. Spectroscopy of semiconductor meta-device building blocks (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Butakov, Nikita A.; Schuller, Jon A.

    2015-09-01

    Inspired by the potential of designing highly efficient nanophotonic optical elements, numerous researchers are currently exploring the use of dielectric resonators in constructing meta-devices. A wide range of optical components have been demonstrated, including metasurfaces that act as two-dimensional lenses, gratings, and axicons. At the core of these devices is a dielectric building block, typically a Silicon nano-disk or nano-rod, that supports Mie-like leaky mode excitations with a geometrically tunable amplitude and phase response. Here we present a comprehensive experimental characterization of these building blocks. We elucidate their multipolar mode structure, and explain the dependence on the underlying substrate. We find that fundamentally new buried magnetic modes emerge in high-index substrates, and that Fabry-Perot effects in silicon-on-insulator platforms can be utilized to enhance or suppress specific modes. When individual resonators are arranged into arrays with sub-wavelength periodicities, inter-particle coupling leads to a shift in the resonant response. When the periodicities are on the same order as the operating wavelength, the localized resonances may couple with the global diffraction modes, leading to the possible formation of distinct high-quality-factor surface-lattice-resonant modes, similar to those encountered in plasmonic gratings. We conclude by exploring the behavior of resonators constructed out of active materials, such as polar materials that support phonon-polariton excitations, and phase-change materials with tunable dielectric constants.

  8. Formation of galactic building blocks in cosmological hydrodynamic simulations

    NASA Astrophysics Data System (ADS)

    Chun, Kyungwon; Shin, Jihye; Kim, Sungsoo S.

    2015-08-01

    We aim to investigate the formation of primordial globular clusters (GCs) and dwarf galaxies as galactic building blocks in the Milky Way-like galaxy with cosmological zoom-in simulations. To accomplish our research goal, we modified cosmological hydrodynamic code, GADGET-2, such that it includes radiative heating and cooling, reionization (z < 8.9) of the Universe, UV shielding (nshield > 0.014cm-3), star formation, and supernova explosion. We first performed a dark matter(DM)-only, low resolution simulation with 32Mpc/h on a side to find the host halo (~10×1012 M⊙), and then resimulated a cubic box of a side length 4Mpc/h with 130 million DM and gas particles from z = 49. The mass of each particle is Mdm = 3.4×104 M⊙ and Mgas = 6.3×103 M⊙, thus the GCs and dwarf galaxies can be resolved with more than hundreds and thousands particles, respectively. Here, we present various properties of the building blocks such as mass function, formation epochs, baryon-to-dark matter ratio, metallicity, spatial distribution, and merger history on the host halo as functions of redshift.

  9. Supramolecular Hydrogels Made of the Basic Biological Building Blocks

    PubMed Central

    Du, Xuewen; Zhou, Jie; Xu, Bing

    2014-01-01

    As a consequence of the self-assembly of small organic molecules in water, supramolecular hydrogels are evolving from serendipitous events during organic synthesis to become a new type of materials that promise increased applications in biomedicine. In this focus review, we describe the recent development on the use of basic biological building blocks for creating molecules that act as hydrogelators and the potential applications of the corresponding hydrogels. After introducing the concept of supramolecular hydrogels and defining the scope of this review, we briefly describe the methods for making and characterizing supramolecular hydrogels. Then, we discuss representative hydrogelators according to the categories of their building blocks, such as amino acids, nucleobases, and saccharides, and highlight the applications of the hydrogels when necessary. Finally, we offer our perspectives and outlooks on this fast-growing field at the interface of organic chemistry, materials, biology, and medicine. By providing a snapshot for chemists, engineers, and medical scientists, we hope that this focus review will contribute to the development of multidisciplinary research on supramolecular hydrogels for a wide range of applications in different fields. PMID:24623474

  10. PAMAM Dendrimers as Quantized Building Blocks for Novel Nanostructures

    PubMed Central

    van Dongen, Mallory A.; Vaidyanathan, S.; Banaszak Holl, Mark M.

    2013-01-01

    The desire to synthesize soft supramolecular structures with size scales similar to biological systems has led to work in assembly of polymeric nanomaterials. Recent advances in the isolation of generationally homogenous poly(amidoamine) (PAMAM) dendrimer enables their use as quantized building blocks. Here, we report their assembly into precise nanoclusters. In this work, click-functional ligands are stochastically conjugated to monomeric generation 5 PAMAM dendrimer and separated via reverse-phase HPLC to isolate dendrimers with precise numbers of click ligands per dendrimer particle. The click-ligand/dendrimer conjugates are then employed as modular building blocks for the synthesis of defined nanostructures. Complimentary click chemistry employing dendrimers with 1, 2, 3, or 4 ring-strained cyclooctyne ligands and dendrimers with 1 azide ligand were utilized to prepare megamer structures containing 2 to 5 ~30,000 kDa monomer units as characterized by mass spectrometry, size exclusion chromatography, and reverse-phase liquid chromatography. The resulting structures are flexible with masses ranging from 60,000 to 150,000 kDa, and are soluble in water, methanol, and dimethylsulfoxide. PMID:24319491

  11. Supramolecular hydrogels made of basic biological building blocks.

    PubMed

    Du, Xuewen; Zhou, Jie; Xu, Bing

    2014-06-01

    As a consequence of the self-assembly of small organic molecules in water, supramolecular hydrogels are evolving from serendipitous events during organic synthesis to become a new type of materials that hold promise for applications in biomedicine. In this Focus Review, we describe recent advances in the use of basic biological building blocks for creating molecules that act as hydrogelators and the potential applications of the corresponding hydrogels. After introducing the concept of supramolecular hydrogels and defining the scope of this review, we briefly describe the methods for making and characterizing supramolecular hydrogels. We then discuss representative hydrogelators according to the categories of their building blocks, such as amino acids, nucleobases, and saccharides, and highlight the applications of the hydrogels when necessary. Finally, we offer our perspective and outlook on this fast-growing field at the interface of organic chemistry, materials, biology, and medicine. By providing a snapshot for chemists, engineers, and medical scientists, we hope that this Focus Review will contribute to the development of multidisciplinary research on supramolecular hydrogels for a wide range of applications in different fields. PMID:24623474

  12. 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

  13. Galaxy satellites; building blocks and the hierarchical clustering paradigm

    NASA Astrophysics Data System (ADS)

    Padilla, N. D.; Lagos, C.; Cora, S. A.

    We study the properties of building blocks (BBs, i.e. accreted satellites) and surviving satellites of present-day galaxies using a semi-analytic model of galaxy formation in the context of a concordance Cold Dark Mat- ter (CDM) cosmology. We consider large numbers of dark-matter (DM) halo merger trees spanning a wide range of masses ( 1 × 1010 to 2.14 × 1015 M ). Our simulated galaxies show higher metallicities for BBs with respect to surviving satellites, an effect produced by the same processes re- sponsible for the build-up of the mass-metallicity relation. We prove that these metallicity differences arise from the higher peak in the density fluctu- ation field occupied by BBs and central galaxies which have collapsed into a single object earlier than surviving satellites. BBs start to form stars ear- lier, during the peak of the merger activity in the universe, and build up half of their final stellar mass (measured at the moment of disruption) up to four times faster than surviving satellites. Surviving satellites keep increasing their stellar masses rather quiescently from their formation until z 1. The difference between the metallicities of satellites, BBs and central galaxies depends on the host DM halo mass, in a way that can be used as a further test for the concordance cosmology.

  14. 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

  15. Molecular gauge blocks for building on the nanoscale.

    PubMed

    Grunder, Sergio; Valente, Cory; Whalley, Adam C; Sampath, Srinivasan; Portmann, Jürg; Botros, Youssry Y; Stoddart, J Fraser

    2012-12-01

    for the compounds with 1-3 chiral axes was established, and a contemporary mathematical way was found to describe the sequence. The development of the ways and means to make molecular gauge building blocks will have positive repercussions on the control of nanostructures in general. Their incorporation into extended structures with the MOF-74 topology provides an excellent demonstration of the potential usefulness of these molecular gauge blocks. PMID:23090871

  16. 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

  17. Linked supramolecular building blocks for enhanced cluster formation

    DOE PAGESBeta

    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.

  18. 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.

  19. 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.

  20. Building Blocks of the Milky Way's Stellar Halo

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    We study the assembly history of the stellar halo of Milky Way-like galaxies using the six high-resolution Aquarius dark matter simulations combined with the Munich-Groningen semi-analytic galaxy formation model. Our goal is to understand the stellar population contents of the building blocks of the Milky Way halo, including their star formation histories and chemical evolution, as well as their internal dynamical properties. We are also interested in how they relate or are different from the surviving satellite population. Finally, we will use our models to compare to observations of halo stars in an attempt to reconstruct the assembly history of the Milky Way's stellar halo itself.

  1. Microbial production of building block chemicals and polymers.

    PubMed

    Lee, Jeong Wook; Kim, Hyun Uk; Choi, Sol; Yi, Jongho; Lee, Sang Yup

    2011-12-01

    Owing to our increasing concerns on the environment, climate change, and limited natural resources, there has recently been considerable effort exerted to produce chemicals and materials from renewable biomass. Polymers we use everyday can also be produced either by direct fermentation or by polymerization of monomers that are produced by fermentation. Recent advances in metabolic engineering combined with systems biology and synthetic biology are allowing us to more systematically develop superior strains and bioprocesses for the efficient production of polymers and monomers. Here, we review recent trends in microbial production of building block chemicals that can be subsequently used for the synthesis of polymers. Also, recent successful cases of direct one-step production of polymers are reviewed. General strategies for the production of natural and unnatural platform chemicals are described together with representative examples. PMID:21420291

  2. 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.

  3. The building blocks and motifs of RNA architecture

    PubMed Central

    Leontis, Neocles B; Lescoute, Aurelie; Westhof, Eric

    2010-01-01

    RNA motifs can be defined broadly as recurrent structural elements containing multiple intramolecular RNA–RNA interactions, as observed in atomic-resolution RNA structures. They constitute the modular building blocks of RNA architecture, which is organized hierarchically. Recent work has focused on analyzing RNA backbone conformations to identify, define and search for new instances of recurrent motifs in X-ray structures. One current view asserts that recurrent RNA strand segments with characteristic backbone configurations qualify as independent motifs. Other considerations indicate that, to characterize modular motifs, one must take into account the larger structural context of such strand segments. This follows the biologically relevant motivation, which is to identify RNA structural characteristics that are subject to sequence constraints and that thus relate RNA architectures to sequences. PMID:16713707

  4. Linked Supramolecular Building Blocks for Enhanced Cluster Formation

    PubMed Central

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

    2015-01-01

    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. PMID:25641542

  5. Sequence-defined polymers via orthogonal allyl acrylamide building blocks.

    PubMed

    Porel, Mintu; Alabi, Christopher A

    2014-09-24

    Biological systems have long recognized the importance of macromolecular diversity and have evolved efficient processes for the rapid synthesis of sequence-defined biopolymers. However, achieving sequence control via synthetic methods has proven to be a difficult challenge. Herein we describe efforts to circumvent this difficulty via the use of orthogonal allyl acrylamide building blocks and a liquid-phase fluorous support for the de novo design and synthesis of sequence-specific polymers. We demonstrate proof-of-concept via synthesis and characterization of two sequence-isomeric 10-mer polymers. (1)H NMR and LCMS were used to confirm their chemical structure while tandem MS was used to confirm sequence identity. Further validation of this methodology was provided via the successful synthesis of a sequence-specific 16-mer polymer incorporating nine different monomers. This strategy thus shows promise as an efficient approach for the assembly of sequence-specific functional polymers. PMID:25204618

  6. The agile transversal filter - A flexible building block for ICNIA

    NASA Astrophysics Data System (ADS)

    Botha, D. G.; Smead, F. W.

    Integrated Communications, Navigation and Identification Avionics (ICNIA) is an advanced development program to demonstrate an integrated systems approach to the implementation of functions normally performed by a collection of independent black boxes. The system design partitions all CNI functions to optimize modular commonality within the ICNIA system. One function required in many parallel channels is the processing of signals with instantaneous bandwidths of 10 MHz or less. A specific implementation is the Narrow Band Agile Transversal Filter (NBATF), which can be implemented in state-of-the-art technology, can process signals with a variety of algorithms selectable under software control, and can be replicated within the system, as required, to perform the total set of functions. The NBATF constitutes a building block module within the ICNIA system.

  7. Thousands of Milky Ways: galaxy satellites and building blocks

    NASA Astrophysics Data System (ADS)

    Padilla, Nelson; Lagos, Claudia; Cora, Sofía

    2010-04-01

    A semi-analytic model of galaxy formation with and without active galactic nuclei feedback is used to study the nature of possible building blocks (BBs) of z = 0 galaxies, including those of Milky-Way types. We find that BBs can show an important range of properties arising from environmental variables such as host halo mass, and whether a galaxy is a satellite within its host halo; the stellar formation histories are comparatively faster and the chemical enrichment is more efficient in BBs than in surviving satellites, in accordance with recent metallicity measurements for the Milky Way. These results can be used in combination with observational constraints to continue probing the ability of the cold dark-matter scenario to reproduce the history of galaxy demography in the Universe.

  8. 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

    2016-04-01

    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. PMID:26453245

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

    DOE PAGESBeta

    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. 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.

  11. 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

  12. Optical Activity of Anisotropic Achiral Surfaces

    SciTech Connect

    Verbiest, T.; Kauranen, M.; Van Rompaey, Y.; Persoons, A. |

    1996-08-01

    Anisotropic achiral surfaces respond differently to left- and right-hand circularly polarized light. This occurs when the orientation of the surface with respect to an otherwise achiral experimental setup makes the total geometry chiral. Such optical activity is demonstrated in second-harmonic generation from an anisotropic thin molecular film. The circular-difference response reverses sign as the handedness of the geometry is reversed and vanishes when the setup possesses a mirror plane. The results are explained within the electric-dipole-allowed second-order surface nonlinearity. {copyright} {ital 1996 The American Physical Society.}

  13. 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.

  14. Identifying the Evolutionary Building Blocks of the Cardiac Conduction System

    PubMed Central

    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. PMID:22984480

  15. A droplet-based building block approach for bladder smooth muscle cell (SMC) proliferation.

    PubMed

    Xu, F; Moon, S J; Emre, A E; Turali, E S; Song, Y S; Hacking, S A; Nagatomi, J; Demirci, U

    2010-03-01

    Tissue engineering based on building blocks is an emerging method to fabricate 3D tissue constructs. This method requires depositing and assembling building blocks (cell-laden microgels) at high throughput. The current technologies (e.g., molding and photolithography) to fabricate microgels have throughput challenges and provide limited control over building block properties (e.g., cell density). The cell-encapsulating droplet generation technique has potential to address these challenges. In this study, we monitored individual building blocks for viability, proliferation and cell density. The results showed that (i) SMCs can be encapsulated in collagen droplets with high viability (>94.2 +/- 3.2%) for four cases of initial number of cells per building block (i.e. 7 +/- 2, 16 +/- 2, 26 +/- 3 and 37 +/- 3 cells/building block). (ii) Encapsulated SMCs can proliferate in building blocks at rates that are consistent (1.49 +/- 0.29) across all four cases, compared to that of the controls. (iii) By assembling these building blocks, we created an SMC patch (5 mm x 5 mm x 20 microm), which was cultured for 51 days forming a 3D tissue-like construct. The histology of the cultured patch was compared to that of a native rat bladder. These results indicate the potential of creating 3D tissue models at high throughput in vitro using building blocks. PMID:20811120

  16. 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.

  17. Power electronic building block (PEDD) workshop. Trip report

    SciTech Connect

    Johnson, G.W.

    1995-10-09

    I attended the Power Electronic Building Block (PEBB) workshop at DOE HQ on June 21,1995. Accompanying me was Doug Hopkins, who is contracting with the Lab through Mark Newton on power electronics. The PEBB concept, and the workshop in particular, are sponsored by the Office of Naval Research (ONR) and DOE. The general concept behind PEBB is a ``second electronics revolution`` facilitated by a single-package, smart, multi-function power control block. The PEBB will potentially replace all conventional power electronic elements at scales from watts to megawatts, thus shifting power engineering from circuit design to system design. ONR is interested because power distribution aboard ships is expensive, complex, and bulky, and getting worse. The same applies to aircraft and many other military systems. DOE`s interest is in electric vehicles, utility power systems, and various end-use applications such as adjustable speed drives. There was obvious enthusiasm from industry, academia, and Government at this workshop. The PEBB concept is in its infancy. Exactly what a PEBB will encompass is still up for discussion. What is certain is that everything is up to industry: standards, innovations, marketing strategies, etc. ONR and DOE are only acting as facilitators and coordinators, and perhaps offering a little seed money. The program will be long-term but fast-paced, relying on concurrent engineering in a serious way. Great strides are required in semiconductors, packaging, controls, and system design. ONR want to put a big knee in the historic power density and dollar-per-watt curves, starting right now.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Micro-Watt building blocks for biomedical RF tranceivers.

    PubMed

    Taris, T; Kraimia, H; Begueret, J-B; Deval, Y

    2011-01-01

    The development of Wireless Body Area Network (WBAN) is a key point enabling the mobility health. Among the most critical constrains in WBAN implementation is the power consumption of wireless featuring nodes. This work focuses on the development of ultra low power radio building blocks dedicated to 2.4 GHz ISM band. A novel design approach based on device optimization is first presented. It is then applied to the implementation of a Low Noise Amplifier (LNA) and a mixer in a 0.13 μm CMOS technology. The LNA provides a 13.1 dB gain and a 5.3 dB NF for a 60 μW/0.4 V power consumption. The mixer achieves a conversion gain of 17.5 dB and a NF of 12 dB at 0 dBm LO power. It consumes 350 μW for a 0.8 V supply. PMID:22255670

  3. Nanobiotechnology with S-layer proteins as building blocks.

    PubMed

    Sleytr, Uwe B; Schuster, Bernhard; Egelseer, Eva M; Pum, Dietmar; Horejs, Christine M; Tscheliessnig, Rupert; Ilk, Nicola

    2011-01-01

    One of the key challenges in nanobiotechnology is the utilization of self- assembly systems, wherein molecules spontaneously associate into reproducible aggregates and supramolecular structures. In this contribution, we describe the basic principles of crystalline bacterial surface layers (S-layers) and their use as patterning elements. The broad application potential of S-layers in nanobiotechnology is based on the specific intrinsic features of the monomolecular arrays composed of identical protein or glycoprotein subunits. Most important, physicochemical properties and functional groups on the protein lattice are arranged in well-defined positions and orientations. Many applications of S-layers depend on the capability of isolated subunits to recrystallize into monomolecular arrays in suspension or on suitable surfaces (e.g., polymers, metals, silicon wafers) or interfaces (e.g., lipid films, liposomes, emulsomes). S-layers also represent a unique structural basis and patterning element for generating more complex supramolecular structures involving all major classes of biological molecules (e.g., proteins, lipids, glycans, nucleic acids, or combinations of these). Thus, S-layers fulfill key requirements as building blocks for the production of new supramolecular materials and nanoscale devices as required in molecular nanotechnology, nanobiotechnology, biomimetics, and synthetic biology. PMID:21999999

  4. 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. PMID:12836031

  5. PSD95 nanoclusters are postsynaptic building blocks in hippocampus circuits

    PubMed Central

    Broadhead, Matthew J.; Horrocks, Mathew H.; Zhu, Fei; Muresan, Leila; Benavides-Piccione, Ruth; DeFelipe, Javier; Fricker, David; Kopanitsa, Maksym V.; Duncan, Rory R.; Klenerman, David; Komiyama, Noboru H.; Lee, Steven F.; Grant, Seth G. N.

    2016-01-01

    The molecular features of synapses in the hippocampus underpin current models of learning and cognition. Although synapse ultra-structural diversity has been described in the canonical hippocampal circuitry, our knowledge of sub-synaptic organisation of synaptic molecules remains largely unknown. To address this, mice were engineered to express Post Synaptic Density 95 protein (PSD95) fused to either eGFP or mEos2 and imaged with two orthogonal super-resolution methods: gated stimulated emission depletion (g-STED) microscopy and photoactivated localisation microscopy (PALM). Large-scale analysis of ~100,000 synapses in 7 hippocampal sub-regions revealed they comprised discrete PSD95 nanoclusters that were spatially organised into single and multi-nanocluster PSDs. Synapses in different sub-regions, cell-types and locations along the dendritic tree of CA1 pyramidal neurons, showed diversity characterised by the number of nanoclusters per synapse. Multi-nanocluster synapses were frequently found in the CA3 and dentate gyrus sub-regions, corresponding to large thorny excrescence synapses. Although the structure of individual nanoclusters remained relatively conserved across all sub-regions, PSD95 packing into nanoclusters also varied between sub-regions determined from nanocluster fluorescence intensity. These data identify PSD95 nanoclusters as a basic structural unit, or building block, of excitatory synapses and their number characterizes synapse size and structural diversity. PMID:27109929

  6. Building blocks of temporal filters in retinal synapses.

    PubMed

    Suh, Bongsoo; Baccus, Stephen A

    2014-10-01

    Sensory systems must be able to extract features of a stimulus to detect and represent properties of the world. Because sensory signals are constantly changing, a critical aspect of this transformation relates to the timing of signals and the ability to filter those signals to select dynamic properties, such as visual motion. At first assessment, one might think that the primary biophysical properties that construct a temporal filter would be dynamic mechanisms such as molecular concentration or membrane electrical properties. However, in the current issue of PLOS Biology, Baden et al. identify a mechanism of temporal filtering in the zebrafish and goldfish retina that is not dynamic but is in fact a structural building block-the physical size of a synapse itself. The authors observe that small, bipolar cell synaptic terminals are fast and highly adaptive, whereas large ones are slower and adapt less. Using a computational model, they conclude that the volume of the synaptic terminal influences the calcium concentration and the number of available vesicles. These results indicate that the size of the presynaptic terminal is an independent control for the dynamics of a synapse and may reveal aspects of synaptic function that can be inferred from anatomical structure. PMID:25333721

  7. Biological magnetic cellular spheroids as building blocks for tissue engineering

    PubMed Central

    Mattix, Brandon; Olsen, Timothy R.; Gu, Yu; Casco, Megan; Herbst, Austin; Simionescu, Dan T.; Visconti, Richard P.; Kornev, Konstantin G.; Alexis, Frank

    2016-01-01

    Magnetic nanoparticles (MNPs), primarily iron oxide nanoparticles, have been incorporated into cellular spheroids to allow for magnetic manipulation into desired shapes, patterns and 3-D tissue constructs using magnetic forces. However, the direct and long-term interaction of iron oxide nanoparticles with cells and biological systems can induce adverse effects on cell viability, phenotype and function, and remain a critical concern. Here we report the preparation of biological magnetic cellular spheroids containing magnetoferritin, a biological MNP, capable of serving as a biological alternative to iron oxide magnetic cellular spheroids as tissue engineered building blocks. Magnetoferritin NPs were incorporated into 3-D cellular spheroids with no adverse effects on cell viability up to 1 week. Additionally, cellular spheroids containing magnetoferritin NPs were magnetically patterned and fused into a tissue ring to demonstrate its potential for tissue engineering applications. These results present a biological approach that can serve as an alternative to the commonly used iron oxide magnetic cellular spheroids, which often require complex surface modifications of iron oxide NPs to reduce the adverse effects on cells. PMID:24176725

  8. Biological magnetic cellular spheroids as building blocks for tissue engineering.

    PubMed

    Mattix, Brandon; Olsen, Timothy R; Gu, Yu; Casco, Megan; Herbst, Austin; Simionescu, Dan T; Visconti, Richard P; Kornev, Konstantin G; Alexis, Frank

    2014-02-01

    Magnetic nanoparticles (MNPs), primarily iron oxide nanoparticles, have been incorporated into cellular spheroids to allow for magnetic manipulation into desired shapes, patterns and 3-D tissue constructs using magnetic forces. However, the direct and long-term interaction of iron oxide nanoparticles with cells and biological systems can induce adverse effects on cell viability, phenotype and function, and remain a critical concern. Here we report the preparation of biological magnetic cellular spheroids containing magnetoferritin, a biological MNP, capable of serving as a biological alternative to iron oxide magnetic cellular spheroids as tissue engineered building blocks. Magnetoferritin NPs were incorporated into 3-D cellular spheroids with no adverse effects on cell viability up to 1 week. Additionally, cellular spheroids containing magnetoferritin NPs were magnetically patterned and fused into a tissue ring to demonstrate its potential for tissue engineering applications. These results present a biological approach that can serve as an alternative to the commonly used iron oxide magnetic cellular spheroids, which often require complex surface modifications of iron oxide NPs to reduce the adverse effects on cells. PMID:24176725

  9. 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.

  10. Distributed Computing Software Building-Blocks for Ubiquitous Computing Societies

    NASA Astrophysics Data System (ADS)

    Kim, K. H. (Kane

    The steady approach of advanced nations toward realization of ubiquitous computing societies has given birth to rapidly growing demands for new-generation distributed computing (DC) applications. Consequently, economic and reliable construction of new-generation DC applications is currently a major issue faced by the software technology research community. What is needed is a new-generation DC software engineering technology which is at least multiple times more effective in constructing new-generation DC applications than the currently practiced technologies are. In particular, this author believes that a new-generation building-block (BB), which is much more advanced than the current-generation DC object that is a small extension of the object model embedded in languages C++, Java, and C#, is needed. Such a BB should enable systematic and economic construction of DC applications that are capable of taking critical actions with 100-microsecond-level or even 10-microsecond-level timing accuracy, fault tolerance, and security enforcement while being easily expandable and taking advantage of all sorts of network connectivity. Some directions considered worth pursuing for finding such BBs are discussed.

  11. 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

  12. 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…

  13. 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. PMID:27195740

  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. Elemental building blocks of the slow solar wind

    NASA Astrophysics Data System (ADS)

    Kepko, L.; Viall, N. M.; Lepri, S. T.

    2014-12-01

    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. A distinguishing characteristic of the slow solar wind is the high variability of the plasma parameters, such as magnetic field, velocity, density, composition, and charge state. Many previous studies of the slow solar wind have examined trends in the composition and charge states over long time scales and using data with comparatively low temporal resolution. In this study, we take advantage of high time resolution (12 min) measurements of the charge-state abundances recently reprocessed by the ACE SWICS science team to probe the timescales of solar wind variability of coherent structures at relatively small scales (<2000 Mm, or ~ 90 minutes at slow wind speeds). We use an interval of slow solar wind containing quasi pressure-balanced, periodic number density structures previously studied by Kepko et al and shown to be important in solar wind-magnetospheric coupling. The combination of high temporal resolution composition measurements and the clearly identified boundaries of the periodic structures allows us to probe the elemental slow solar wind flux tubes/structures. We use this train of 2000Mm periodic density structures as tracers of solar wind origin and/or acceleration. We find that each 2000 Mm parcel of slow solar wind, though its speed is steady, exhibits the complete range of charge state and composition variations expected for the entire range of slow solar wind, in a repeated sequence. Each parcel cycles through three states: 1) 'normal' slow wind, 2) compositionally slow wind with very high density, and 3) compositionally fast but typical slow solar wind density. We conclude by suggesting these structures form elemental building blocks of the slow solar wind, and discuss whether it is necessary to decouple separately the process(es) responsible for the release and acceleration.

  17. Pyrazine-imide complexes: reversible redox and MOF building blocks.

    PubMed

    Cowan, Matthew G; Miller, Reece G; Brooker, Sally

    2015-02-14

    The synthesis of the symmetric pyrazine imide ligand, N-(2-pyrazylcarbonyl)-2-pyrazinecarboxamide, (Hdpzca) and five new first row transition metal complexes of it are reported: [M(II)(dpzca)(2)], M(II) = Fe, Cu, Zn; [Cu(II)(dpzca)(H(2)O)(2)]BF(4), [Cu(II)(dpzca)(H(2)O)(3)](2)SiF(6). The crystal structures of Hdpzca, [Co(II)(dpzca)(2)], [Cu(II)(dpzca)(2)], {[Co(III)(dpzca)(2)](BF(4))}(2)·5CH(3)CN and [Cu(II)(dpzca)(H(2)O)(3))](2)SiF(6)·2H(2)O were determined and reveal an orthogonal positioning of the 'spare' pyrazine nitrogen atoms and 'spare' pairs of imide oxygen atoms. The [M(II)(dpzca)(2)] complexes are therefore useful six-coordinate building blocks for producing larger supramolecular assemblies. Two examples of secondary assembly of [M(II)(dpzca)(2)] complexes, with M = Co and Ni, with silver nitrate gave single crystals; {[Co(III)(dpzca)(2)Ag](NO(3))(2)·2H(2)O}n and {([Ni(II)(dpzca)(2)Ag(I)(1/2)](1/2NO(3))(xH(2)O}n were structurally characterised. The redox processes of [M(II)(dpzca)(2)], with M(II) = Fe, Ni, Cu and Zn, are reported and, as seen for M(II) = Co, reversible metal- and ligand-based redox processes are observed, with E(m)(M(II)/M(III)) values 0.15-0.24 V higher than for the analogous complexes of Hpypzca (non-symmetric pyridine/pyrazine imide ligand), and 0.35-0.36 V higher than for the complexes of Hbpca (symmetric pyridine imide ligand). PMID:25563508

  18. Unidirectional rotary motion in achiral molecular motors.

    PubMed

    Kistemaker, Jos C M; Štacko, Peter; Visser, Johan; Feringa, Ben L

    2015-11-01

    Control of the direction of motion is an essential feature of biological rotary motors and results from the intrinsic chirality of the amino acids from which the motors are made. In synthetic autonomous light-driven rotary motors, point chirality is transferred to helical chirality, and this governs their unidirectional rotation. However, achieving directional rotary motion in an achiral molecular system in an autonomous fashion remains a fundamental challenge. Here, we report an achiral molecular motor in which the presence of a pseudo-asymmetric carbon atom proved to be sufficient for exclusive autonomous disrotary motion of two appended rotor moieties. Isomerization around the two double bonds enables both rotors to move in the same direction with respect to their surroundings--like wheels on an axle--demonstrating that autonomous unidirectional rotary motion can be achieved in a symmetric system. PMID:26492009

  19. Unidirectional rotary motion in achiral molecular motors

    NASA Astrophysics Data System (ADS)

    Kistemaker, Jos C. M.; Štacko, Peter; Visser, Johan; Feringa, Ben L.

    2015-11-01

    Control of the direction of motion is an essential feature of biological rotary motors and results from the intrinsic chirality of the amino acids from which the motors are made. In synthetic autonomous light-driven rotary motors, point chirality is transferred to helical chirality, and this governs their unidirectional rotation. However, achieving directional rotary motion in an achiral molecular system in an autonomous fashion remains a fundamental challenge. Here, we report an achiral molecular motor in which the presence of a pseudo-asymmetric carbon atom proved to be sufficient for exclusive autonomous disrotary motion of two appended rotor moieties. Isomerization around the two double bonds enables both rotors to move in the same direction with respect to their surroundings—like wheels on an axle—demonstrating that autonomous unidirectional rotary motion can be achieved in a symmetric system.

  20. Light sensitive achiral polar polymeric composites

    NASA Astrophysics Data System (ADS)

    González-Henríquez, C. M.; Soto-Bustamante, E. A.; Vergara-Toloza, R. O.; Haase, W.

    2011-07-01

    The occurrence of antiferroelectric phenomenon in achiral composites composed of azo-benzene containing liquid crystals was observed. Some of the composites evidenced typical antiferroelectric polarization hysteresis loop in the mesophase, showing bilayer smectic C 2 mesophases with some interdigitation grade at the layer interface in a broad temperature range. Surprisingly composites of similar structure developed pyroelectricity but not switchable states. This new class of antiferroelectric materials is also capable of producing E-Z photoisomerization making them good candidates for energy harvesting.

  1. Science Support: The Building Blocks of Active Data Curation

    NASA Astrophysics Data System (ADS)

    Guillory, A.

    2013-12-01

    While the scientific method is built on reproducibility and transparency, and results are published in peer reviewed literature, we have come to the digital age of very large datasets (now of the order of petabytes and soon exabytes) which cannot be published in the traditional way. To preserve reproducibility and transparency, active curation is necessary to keep and protect the information in the long term, and 'science support' activities provide the building blocks for active data curation. With the explosive growth of data in all fields in recent years, there is a pressing urge for data centres to now provide adequate services to ensure long-term preservation and digital curation of project data outputs, however complex those may be. Science support provides advice and support to science projects on data and information management, from file formats through to general data management awareness. Another purpose of science support is to raise awareness in the science community of data and metadata standards and best practice, engendering a culture where data outputs are seen as valued assets. At the heart of Science support is the Data Management Plan (DMP) which sets out a coherent approach to data issues pertaining to the data generating project. It provides an agreed record of the data management needs and issues within the project. The DMP is agreed upon with project investigators to ensure that a high quality documented data archive is created. It includes conditions of use and deposit to clearly express the ownership, responsibilities and rights associated with the data. Project specific needs are also identified for data processing, visualization tools and data sharing services. As part of the National Centre for Atmospheric Science (NCAS) and National Centre for Earth Observation (NCEO), the Centre for Environmental Data Archival (CEDA) fulfills this science support role of facilitating atmospheric and Earth observation data generating projects to ensure

  2. Haloalkynes: a powerful and versatile building block in organic synthesis.

    PubMed

    Wu, Wanqing; Jiang, Huanfeng

    2014-08-19

    Inspired by the need for green and sustainable chemistry, modern synthetic chemists have been seeking general and practical ways to construct complex molecules while maximizing atom economy and minimizing synthetic steps. Over the past few decades, considerable progress has been made to fulfill these goals by taking advantage of transition metal catalysis and chemical reagents with diverse and tunable reactivities. In recent years, haloalkynes have emerged as powerful and versatile building blocks in a variety of synthetic transformations, which can be generally conceived as a dual functionalized molecules, and different reaction intermediates, such as σ-acetylene-metal, π-acetylene-metal, and halovinylidene-metal complexes, can be achieved and undergo further transformations. Additionally, the halogen moieties can be retained during the reaction processes, which makes the subsequent structural modifications and tandem carbon-carbon or carbon-heteroatom bond formations possible. As a consequence, impressive effort has been devoted to this attractive area, and some elegant work has been done over the past several years. This Account highlights some of the recent progress on the development of efficient and practical synthetic methods involving haloalkyne reagents in our laboratory and in others around the world, which showcase the synthetic power of haloalkynes for rapid assembly of complex molecular structures. The focus is primarily on reaction development with haloalkynes, such as cross-coupling reactions, nucleophilic additions, and cycloaddition reactions. The designed approaches, as well as serendipitous observations, will be discussed with special emphasis placed on the mechanistic aspects and the synthetic utilities of the obtained products. These transformations can lead directly to heteroatom-containing products and introduce structural complexity rapidly, thus providing new strategies and quick access to a wide range of functionalized products including

  3. 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

  4. 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

  5. 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.

  6. 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)

  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. Biocatalytic approaches to a key building block for the anti-thrombotic agent ticagrelor.

    PubMed

    Hugentobler, Katharina G; Sharif, Humera; Rasparini, Marcello; Heath, Rachel S; Turner, Nicholas J

    2016-09-14

    three complementary biocatalytic routes were examined for the synthesis of the cyclopropyl amine (1R,2S)-2, which is a key building block for the anti-thrombotic agent ticagrelor 1. By employing either a ketoreductase, amidase or lipase biocatalyst, the key building blocks for synthesis of the amine 2 were obtained in 99.9, 92.5 and 46.3 ee, respectively. PMID:27470519

  9. Composition of clusters and building blocks in amylopectins from maize mutants deficient in starch synthase III.

    PubMed

    Zhu, Fan; Bertoft, Eric; Seetharaman, Koushik

    2013-12-18

    Branches in amylopectin are distributed along the backbone. Units of the branches are building blocks (smaller) and clusters (larger) based on the distance between branches. In this study, composition of clusters and building blocks of amylopectins from dull1 maize mutants deficient in starch synthase III (SSIII) with a common genetic background (W64A) were characterized and compared with the wild type. Clusters were produced from amylopectins by partial hydrolysis using α-amylase of Bacillus amyloliquefaciens and were subsequently treated with phosphorylase a and β-amylase to produce φ,β-limit dextrins. Clusters were further extensively hydrolyzed with the α-amylase to produce building blocks. Structures of clusters and building blocks were analyzed by diverse chromatographic techniques. The results showed that the dull1 mutation resulted in larger clusters with more singly branched building blocks. The average cluster contained ~5.4 blocks in dull1 mutants and ~4.2 blocks in the wild type. The results are compared with previous results from SSIII-deficient amo1 barley and suggest fundamental differences in the cluster structures. PMID:24229421

  10. Chiral plasmonic nanostructures on achiral nanopillars.

    PubMed

    Yeom, Bongjun; Zhang, Huanan; Zhang, Hui; Park, Jai Il; Kim, Kyoungwon; Govorov, Alexander O; Kotov, Nicholas A

    2013-11-13

    Chirality of plasmonic films can be strongly enhanced by three-dimensional (3D) out-of-plane geometries. The complexity of lithographic methods currently used to produce such structures and other methods utilizing chiral templates impose limitations on spectral windows of chiroptical effects, the size of substrates, and hence, further research on chiral plasmonics. Here we demonstrate 3D chiral plasmonic nanostructures (CPNs) with high optical activity in the visible spectral range based on initially achiral nanopillars from ZnO. We made asymmetric gold nanoshells on the nanopillars by vacuum evaporation at different inclination and rotation angles to achieve controlled symmetry breaking and obtained both left- and right-rotating isomers. The attribution of chiral optical effects to monolithic enantiomers made in this process was confirmed by theoretical calculations based on their geometry established from scanning electron microscope (SEM) images. The chirality of the nanoshells is retained upon the release from the substrate into a stable dispersion. Deviation of the incident angle of light from normal results in increase of polarization rotation and chiral g-factor as high as -0.3. This general approach for preparation of abiological nanoscale chiral materials can be extended to other out-of plane 3D nanostructures. The large area films made on achiral nanopillars are convenient for sensors, optical devices, and catalysis. PMID:24111695

  11. Magnetic Control of Rigid Achiral Microswimmers

    NASA Astrophysics Data System (ADS)

    Cheang, U.; Meshkati, Farshad; Fu, Henry; Kim, Minjun

    2013-11-01

    We report control of rigid achiral microswimmers in low Reynolds number environments. A rotating magnetic field was used to actuate the microswimmers wirelessly by rotating the microswimmers, which produces propulsion. Previous magnetically actuated microswimmers in bulk fluids have been designed with either flexibility or chiral geometry; we show that simpler geometries with neither flexibility nor chirality can produce propulsion. The microswimmer consists of three magnetic beads conjugated using avidin-biotin linkages into an arc formation. We designed a magnetic field generator consisting of electromagnetic coils arranged in an approximate Helmholtz configuration. A highspeed camera provided realtime imaging of the microswimmers' motion in a PDMS chamber. The rigidity of the microswimmer was characterized by tracking the position of the individual beads and calculating their relative distances. As a function of field strength and rotation frequency, we observed changes in the rotational axis of the microswimmers and the corresponding effects on their velocities. The achiral microswimmers exhibited active propulsion and were controllable in both speed and direction, which demonstrates the possibility for future biomedical applications such as drug delivery.

  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. 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. PMID:25131385

  14. 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

  15. A field study of wind over a simulated block building

    NASA Technical Reports Server (NTRS)

    Frost, W.; Shahabi, A. M.

    1977-01-01

    A full-scale field study of the wind over a simulated two-dimensional building is reported. The study develops an experiment to investigate the structure and magnitude of the wind fields. A description of the experimental arrangement, the type and expected accuracy of the data, and the range of the data are given. The data are expected to provide a fundamental understanding of mean wind and turbulence structure of the wind field around the bluff body. Preliminary analysis of the data demonstrates the reliability and completeness of the data in this regard.

  16. ``Spin inverter'' as building block of All Spin Logic devices

    NASA Astrophysics Data System (ADS)

    Sarkar, Angik; Srinivasan, Srikant; Datta, Supriyo

    2012-02-01

    All-spin logic (ASL) represents a new approach to information processing where the roles of charges and capacitors in charge based transistors are played by spins and magnets, without the need for repeated spin-charge conversion. In our past work, we have presented numerical simulations based on a coupled spin transport and Landau Lifshitz Gilbert model showing that ring oscillators and logic circuits with intrinsic directionality [IEEE Trans. Magn. 47,10, 4026, 2011; Proc. IEDM, 2011)] can be implemented by manipulation of spins in magnetic nanostructures. The aim of this talk is (1) to identify a basic ASL unit that can be interconnected to build up spin circuits analogous to the way transistors are interconnected to build conventional circuits and (2) to present a compact model for this basic unit that can be used to design and analyze large scale spin circuits. We will show that this basic ASL unit is a one-magnet ``spin inverter'' with gain that can be cascaded to accomplish a spin circuit implementation of almost any logic functionality

  17. Four-bit reconfigurable discriminator for frequency identification receivers: A building block approach

    NASA Astrophysics Data System (ADS)

    Espinosa-Espinosa, Moisés.; Llamas-Garro, Ignacio; Oliveira, Bruno Gomes Moura; Melo, Marcos T.; Kim, Jung-Mu

    2016-06-01

    This paper presents a building block approach to design a reconfigurable discriminator (RD), which is the core circuit in frequency identification receivers. The RD is used to identify an unknown signal; the output of the circuit determines a frequency subband where the unknown signal falls into. The proposed building block design approach is scalable and can be used to produce any multibit RD. This design approach can be used to produce RD circuits with more or less resolution for a fixed band of operation, according to the number of bits used for a given design. The building block approach is demonstrated through the design of a 4-bit RD. This design is a two-port device that provides a series readout and can produce 4 bits for frequency identification. The device operates from 1 to 4 GHz, implemented by microstrip lines and PIN diode switches. Simulated and measured responses are in agreement.

  18. An Approach for On-Board Software Building Blocks Cooperation and Interfaces Definition

    NASA Astrophysics Data System (ADS)

    Pascucci, Dario; Campolo, Giovanni; Candia, Sante; Lisio, Giovanni

    2010-08-01

    This paper provides an insight on the Avionic SW architecture developed by Thales Alenia Space Italy (TAS-I) to achieve structuring of the OBSW as a set of self-standing and re-usable building blocks. It is initially described the underlying framework for building blocks cooperation, which is based on ECSSE-70 packets forwarding (for services request to a building block) and standard parameters exchange for data communication. Subsequently it is discussed the high level of flexibility and scalability of the resulting architecture, reporting as example an implementation of the Failure Detection, Isolation and Recovery (FDIR) function which exploits the proposed architecture. The presented approach evolves from avionic SW architecture developed in the scope of the project PRIMA (Mult-Purpose Italian Re-configurable Platform) and has been adopted for the Sentinel-1 Avionic Software (ASW).

  19. 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.

  20. 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.

  1. A mixed molecular building block strategy for the design of nested polyhedron metal-organic frameworks.

    PubMed

    Tian, Dan; Chen, Qiang; Li, Yue; Zhang, Ying-Hui; Chang, Ze; Bu, Xian-He

    2014-01-13

    A mixed molecular building block (MBB) strategy for the synthesis of double-walled cage-based porous metal-organic frameworks (MOFs) is presented. By means of this method, two isostructural porous MOFs built from unprecedented double-walled metal-organic octahedron were obtained by introducing two size-matching C3 -symmetric molecular building blocks with different rigidities. With their unique framework structures, these MOFs provide, to the best of our knowledge, the first examples of double-walled octahedron-based MOFs. PMID:24282117

  2. 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

  3. LEGO® bricks as building blocks for centimeter-scale biological environments: the case of plants.

    PubMed

    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

  4. Small, monogenetic volcanoes: building blocks of the upper oceanic crust

    NASA Astrophysics Data System (ADS)

    Yeo, Isobel A.; Achenbach, Kay L.; Searle, Roger C.; Le Bas, Tim P.

    2010-05-01

    the products of single eruptions. Cones of all heights, but particularly those over 70m, are prone to collapse soon after forming. A variety of mechanisms are examined and collapse triggers may include: a) flank over-steepening, b) building on unstable material, and c) cutting by fissuring. Collapse scarps show two strong alignments, one ridge parallel and one at 30° to the ridge trend; however as cones always collapse downslope, these alignments may be due to the slope angles produced as a result of cone emplacement rather than first order controls on collapses themselves. We estimate the minimum magmatic flux to the surface for this segment to be at least 64,000m3 yr -1, which is equivalent to producing one average volume cone every 3.5 years.

  5. "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,…

  6. 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

  7. 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

  8. 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

  9. Experimental Analysis of Effects of Teacher Attention of Preschool Children's Block Building Behavior. Progress Report.

    ERIC Educational Resources Information Center

    Cooper, Margaret L.

    This study was designed to demonstrate the effects of teacher attention given for specific responses children show when using building blocks. These included the responses of combining triangles to make rectangles, stacking diverse pieces to make a tower, making stairs, making a variation on a model, and making a house-like, enclosed, roofed…

  10. 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

  11. 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…

  12. Here Comes the Future: Information Is the Building Block for Learning

    ERIC Educational Resources Information Center

    Neuman, Delia

    2012-01-01

    The idea that information is the building block for learning is not new. In fact, it has been a core tenet of learning theory since the study of human cognition began. What's new about learning in the twenty-first century is that various dimensions of information have changed--expanding in every conceivable way. Information is now a "24-7"…

  13. The Study of Stress and Competence in Children: A Building Block for Developmental Psychopathology.

    ERIC Educational Resources Information Center

    Garmezy, Norman; And Others

    1984-01-01

    Discusses building blocks for a developmental psychopathology, focusing on studies of risk, competence, and protective factors. Describes studies of stress and competence, giving particular attention to methodology and strategies for data analysis. A three-model approach to stress resistance is also presented, and Project Competence is evaluated…

  14. 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

    2016-08-01

    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. PMID:27365192

  15. 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.

  16. Building Blocks.

    ERIC Educational Resources Information Center

    Black, Susan

    2001-01-01

    Studies show that deteriorating school facilities take their toll on students' and teachers' health and morale. Classrooms should be accessible to the outdoors; clustered around a commons; adaptable and flexible; and aesthetically pleasing. Architects say natural lighting and noise reduction are routine parts of their job. Research studies support…

  17. Structure of clusters and building blocks in amylopectin from African rice accessions.

    PubMed

    Gayin, Joseph; Abdel-Aal, El-Sayed M; Marcone, Massimo; Manful, John; Bertoft, Eric

    2016-09-01

    Enzymatic hydrolysis in combination with gel-permeation and anion-exchange chromatography techniques were employed to characterise the composition of clusters and building blocks of amylopectin from two African rice (Oryza glaberrima) accessions-IRGC 103759 and TOG 12440. The samples were compared with one Asian rice (Oryza sativa) sample (cv WITA 4) and one O. sativa×O. glaberrima cross (NERICA 4). The average DP of clusters from the African rice accessions (ARAs) was marginally larger (DP=83) than in WITA 4 (DP=81). However, regarding average number of chains, clusters from the ARAs represented both the smallest and largest clusters. Overall, the result suggested that the structure of clusters in TOG 12440 was dense with short chains and high degree of branching, whereas the situation was the opposite in NERICA 4. IRGC 103759 and WITA 4 possessed clusters with intermediate characteristics. The commonest type of building blocks in all samples was group 2 (single branched dextrins) representing 40.3-49.4% of the blocks, while groups 3-6 were found in successively lower numbers. The average number of building blocks in the clusters was significantly larger in NERICA 4 (5.8) and WITA 4 (5.7) than in IRGC 103759 and TOG 12440 (5.1 and 5.3, respectively). PMID:27185123

  18. 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.

  19. Building Blocks for Building Skills: An Inventory of Adult Learning Models and Innovations

    ERIC Educational Resources Information Center

    Klein-Collins, Rebecca

    2006-01-01

    The skills of the workforce are an important contributor to the economic vitality of any region, leading economic developers to consider how to connect their efforts to workforce development and help to build the skills of adults generally. This report, produced for the U.S. Department of Labor's Workforce Innovation in Regional Economic…

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

    PubMed

    Zhang, Wei; Huang, Mingjun; Su, Hao; Zhang, Siyu; Yue, Kan; Dong, Xue-Hui; Li, Xiaopeng; Liu, Hao; Zhang, Shuo; Wesdemiotis, Chrys; Lotz, Bernard; Zhang, Wen-Bin; Li, Yiwen; Cheng, Stephen Z D

    2016-01-27

    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

  1. Plasmid Vectors and Molecular Building Blocks for the Development of Genetic Manipulation Tools for Trypanosoma cruzi

    PubMed Central

    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. PMID:24205392

  2. 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. PMID:24205392

  3. 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

  4. Asymmetric transformations of achiral 2,5-cyclohexadienones

    PubMed Central

    Kalstabakken, Kyle A.; Harned, Andrew M.

    2014-01-01

    Cyclohexadienones are versatile platforms for performing asymmetric synthesis as evidenced by the numerous natural product syntheses that exploit their diverse reactivity profile. However, there are few general methods available for the direct asymmetric synthesis of chiral cyclohexadienones. To circumvent this problem, several researchers have developed catalytic asymmetric methods that employ readily available achiral 2,5-cyclohexadienones as substrates. Many of these reactions are desymmetrizations in which one of the enantiotopic alkenes of an achiral dienone is transformed. Others involve selective reaction at one alkene of an unsymmetrically substituted, achiral dienone. This review will cover advances in this area over the last 20 years and the application of these strategies in complex molecule synthesis. PMID:26688596

  5. Chiroptical activity in colloidal quantum dots coated with achiral ligands.

    PubMed

    Melnikau, Dzmitry; Savateeva, Diana; Gaponik, Nikolai; Govorov, Alexander O; Rakovich, Yury P

    2016-01-25

    We studied the chiroptical properties of colloidal solution of CdSe and CdSe/ZnS quantum dots (QDs) with a cubic lattice structure which were initially prepared without use of any chiral molecules and coated with achiral ligands. We demonstrate circular dichroism (CD) activity around first and second excitonic transition of these CdSe based nanocrystals. We consider that this chiroptical activity is caused by imbalance in racemic mixtures of QDs between the left and right handed nanoparticles, which appears as a result of the formation of various defects or incorporation of impurities into crystallographic structure during their synthesis. We demonstrate that optical activity of colloidal solution of CdSe QDs with achiral ligands weakly depends on the QDs size and number of ZnS monolayers, but does not depend on the nature of achiral ligands or polarity of the solution. PMID:26832599

  6. A C60-aryne building block: synthesis of a hybrid all-carbon nanostructure.

    PubMed

    García, D; Rodríguez-Pérez, L; Herranz, M A; Peña, D; Guitián, E; Bailey, S; Al-Galiby, Q; Noori, M; Lambert, C J; Pérez, D; Martín, N

    2016-05-10

    The synthesis of a [60]fullerene-benzyne building block and its further chemical cycloaddition reaction with graphene has resulted in a new all-carbon hybrid material which has been characterized by TGA, FTIR and Raman spectroscopies, XPS as well as AFM and TEM. Based on computational studies, the formation of both [2+2] and [4+2] cycloadducts on the graphene surface is feasible. PMID:27116219

  7. The synthesis of planar sp2 -bonded system from molecular building blocks

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Luo, Hong; Gu, Gong

    Biphenyl and pyrene molecules were deposited onto atomically flat Cu (100) surface as building blocks for the synthesis of planar, conjugated, sp2-bonded system. In situ STM observation confirmed the formation of highly-ordered lattice structure after annealing under UHV condition, as a result of the substrate-assisted dehydrogenation. The electronic properties of the system were examined by STS and will be presented. ONR N00014-15-1-2661.

  8. Eumelanin-inspired core derived from vanillin: a new building block for organic semiconductors.

    PubMed

    Selvaraju, Subhashini; Niradha Sachinthani, K A; Hopson, RaiAnna A; McFarland, Frederick M; Guo, Song; Rheingold, Arnold L; Nelson, Toby L

    2015-02-18

    An eumelanin-inspired core derived from the natural product, vanillin (vanilla bean extract) was utilized for the synthesis of eumelanin-inspired small molecules and polymer via Sonogashira cross coupling. The materials demonstrate that the methyl 4,7-dibromo-5,6-dimethoxy-N-methyl-1H-indole-2-carboxylate core can serve as a new building block for organic semiconductors. PMID:25594078

  9. 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

  10. Methods for estimating wake flow and effluent dispersion near simple block-like buildings

    SciTech Connect

    Hosker, R.P. Jr.

    1981-05-01

    This report is intended as an interim guide for those who routinely face air quality problems associated with near-building exhaust stack placement and height, and the resulting concentration patterns. Available data and methods for estimating wake flow and effluent dispersion near isolated block-like structures are consolidated. The near-building and wake flows are described, and quantitative estimates for frontal eddy size, height and extent of roof and wake cavities, and far wake behavior are provided. Concentration calculation methods for upwind, near-building, and downwind pollutant sources are given. For an upwind source, it is possible to estimate the required stack height, and to place upper limits on the likely near-building concentration. The influences of near-building source location and characteristics relative to the building geometry and orientation are considered. Methods to estimate effective stack height, upper limits for concentration due to flush roof vents, and the effect of changes in rooftop stack height are summarized. Current wake and wake cavity models are presented. Numerous graphs of important expressions have been prepared to facilitate computations and quick estimates of flow patterns and concentration levels for specific simple buildings. Detailed recommendations for additional work are given.

  11. 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).

  12. 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)

  13. 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

    2016-08-01

    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. PMID:27388010

  14. 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.

  15. 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.

  16. Ferroelectric Smectic Phase Formed by Achiral Straight Core Mesogens

    NASA Astrophysics Data System (ADS)

    Stannarius, Ralf; Li, Jianjun; Weissflog, Wolfgang

    2003-01-01

    We report electro-optic experiments in liquid crystalline freestanding films of achiral hockey stick shaped mesogens with a straight aromatic core. The material forms two smectic mesophases. In the higher temperature phase, a spontaneous polarization exists in the smectic layer plane and the films show polar switching in electric fields. It is the first example of a ferroelectric phase formed by nearly rodlike achiral mesogens. Mirror symmetry of the phase is spontaneously broken. We propose a molecular configuration similar to a synclinic ferroelectric (CSPF) high temperature phase and an anticlinic, probably antiferroelectric (CAPA) low temperature phase.

  17. Multi-shape memory polymers achieved by the spatio-assembly of 3D printable thermoplastic building blocks.

    PubMed

    Li, Hongze; Gao, Xiang; Luo, Yingwu

    2016-04-01

    Multi-shape memory polymers were prepared by the macroscale spatio-assembly of building blocks in this work. The building blocks were methyl acrylate-co-styrene (MA-co-St) copolymers, which have the St-block-(St-random-MA)-block-St tri-block chain sequence. This design ensures that their transition temperatures can be adjusted over a wide range by varying the composition of the middle block. The two St blocks at the chain ends can generate a crosslink network in the final device to achieve strong bonding force between building blocks and the shape memory capacity. Due to their thermoplastic properties, 3D printing was employed for the spatio-assembly to build devices. This method is capable of introducing many transition phases into one device and preparing complicated shapes via 3D printing. The device can perform a complex action via a series of shape changes. Besides, this method can avoid the difficult programing of a series of temporary shapes. The control of intermediate temporary shapes was realized via programing the shapes and locations of building blocks in the final device. PMID:26924759

  18. Chiral random grain boundary phase of achiral hockey-stick liquid crystals.

    PubMed

    Chen, Dong; Wang, Haitao; Li, Min; Glaser, Matthew A; Maclennan, Joseph E; Clark, Noel A

    2014-12-01

    A disordered chiral conglomerate, the random grain boundary (RGB) phase, has been observed below the smectic A liquid crystal phase of an achiral, hockey-stick molecule. In cells, the RGB phase appears dark between crossed polarizers but decrossing the polarizers reveals large left- and right-handed chiral domains with opposite optical rotation. Freeze-fracture transmission electron microscopy reveals that the RGB phase is an assembly of randomly oriented blocks of smectic layers, an arrangement that distinguishes the RGB from the dark, chiral conglomerate phases of bent-core mesogens. X-ray diffraction indicates that there is significant layer shrinkage at the SmA-RGB phase transition, which is marked by the collapse of layers with long-range order into small, randomly oriented smectic blocks. PMID:25310113

  19. MSi₂₀H₂₀ aggregates: from simple building blocks to highly magnetic functionalized materials.

    PubMed

    Palagin, Dennis; Reuter, Karsten

    2013-02-26

    Density-functional theory based global geometry optimization is used to scrutinize the possibility of using endohedrally doped hydrogenated Si clusters as building blocks for constructing highly magnetic materials. In contrast to the known clathrate-type facet-sharing, the clusters exhibit a predisposition to aggregation through double Si-Si bridge bonds. For the prototypical CrSi₂₀H₂₀ cluster we show that reducing the degree of hydrogenation may be used to control the number of reactive sites to which other cages can be attached, while still preserving the structural integrity of the building block itself. This leads to a toolbox of CrSi₂₀H(20-2n) monomers with different number of double "docking sites", that allows building network architectures of any morphology. For (CrSi₂₀H₁₈)₂ dimer and [CrSi₂₀H₁₆](CrSi₂₀H₁₈)₂ trimer structures we illustrate that such aggregates conserve the high spin moments of the dopant atoms and are therefore most attractive candidates for cluster-assembled materials with unique magnetic properties. The study suggests that the structural completion of the individual endohedral cages within the doubly bridge bonded structures and the high thermodynamic stability of the obtained aggregates are crucial for potential synthetic polimerization routes via controlled dehydrogenation. PMID:23339372

  20. Computational strategies for the automated design of RNA nanoscale structures from building blocks using NanoTiler☆

    PubMed Central

    Bindewald, Eckart; Grunewald, Calvin; Boyle, Brett; O’Connor, Mary; Shapiro, Bruce A.

    2013-01-01

    One approach to designing RNA nanoscale structures is to use known RNA structural motifs such as junctions, kissing loops or bulges and to construct a molecular model by connecting these building blocks with helical struts. We previously developed an algorithm for detecting internal loops, junctions and kissing loops in RNA structures. Here we present algorithms for automating or assisting many of the steps that are involved in creating RNA structures from building blocks: (1) assembling building blocks into nanostructures using either a combinatorial search or constraint satisfaction; (2) optimizing RNA 3D ring structures to improve ring closure; (3) sequence optimisation; (4) creating a unique non-degenerate RNA topology descriptor. This effectively creates a computational pipeline for generating molecular models of RNA nanostructures and more specifically RNA ring structures with optimized sequences from RNA building blocks. We show several examples of how the algorithms can be utilized to generate RNA tecto-shapes. PMID:18838281

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

    PubMed Central

    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. PMID:26345412

  2. 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. PMID:26345412

  3. Hierarchical coassembly of DNA–triptycene hybrid molecular building blocks and zinc protoporphyrin IX

    PubMed Central

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

    2016-01-01

    Summary 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. PMID:27335759

  4. 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

  5. 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.

  6. Interpenetrating metal-organic frameworks formed by self-assembly of tetrahedral and octahedral building blocks

    SciTech Connect

    Lu Yongming; Lan Yaqian; Xu Yanhong; Su Zhongmin; Li Shunli; Zang Hongying; Xu Guangjuan

    2009-11-15

    To investigate the relationship between topological types and molecular building blocks (MBBs), we have designed and synthesized a series of three-dimensional (3D) interpenetrating metal-organic frameworks based on different polygons or polyhedra under hydrothermal conditions, namely [Cd(bpib){sub 0.5}(L{sup 1})] (1), [Cd(bpib){sub 0.5}(L{sup 2})].H{sub 2}O (2), [Cd(bpib){sub 0.5}(L{sup 3})] (3) and [Cd(bib){sub 0.5}(L{sup 1})] (4), where bpib=1,4-bis(2-(pyridin-2-yl)-1H-imidazol-1-yl)butane, bib=1,4-bis(1H-imidazol-1-yl)butane, H{sub 2}L{sup 1}=4-(4-carboxybenzyloxy)benzoic acid, H{sub 2}L{sup 2}=4,4'-(ethane-1,2-diylbis(oxy))dibenzoic acid and H{sub 2}L{sup 3}=4,4'-(1,4-phenylenebis(methylene))bis(oxy)dibenzoic acid, respectively. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Compounds 1-3 display alpha-Po topological nets with different degrees of interpenetration based on the similar octahedral [Cd{sub 2}(-COO){sub 4}] building blocks. Compound 4 is a six-fold interpenetrating diamondoid net based on tetrahedral MBBs. By careful inspection of these structures, we find that various carboxylic ligands and N-donor ligands with different coordination modes and conformations, and metal centers with different geometries are important for the formation of the different MBBs. It is believed that different topological types lie on different MBBs with various polygons or polyhedra. Such as four- and six-connected topologies are formed by tetrahedral and octahedral building blocks. In addition, with the increase of carboxylic ligands' length, the degrees of interpenetration have been changed in the alpha-Po topological nets. And the luminescent properties of these compounds have been investigated in detail. - Graphical abstract: A series of three-dimensional interpenetrating metal-organic frameworks based on different polygons or polyhedra

  7. Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

    PubMed Central

    Lohse, Mirko; von Krbek, Larissa K S; Radunz, Sebastian; Moorthy, Suresh

    2015-01-01

    Summary Two pairs of divalent and tetravalent porphyrin building blocks carrying the complementary supramolecular crown ether/secondary ammonium ion binding motif have been synthesized and their derived pseudorotaxanes have been studied by a combination of NMR spectroscopy in solution and ESI mass spectrometry in the gas phase. By simple mixing of the components the formation of discrete dimeric and trimeric (metallo)porphyrin complexes predominates, in accordance to binding stoichiometry, while the amount of alternative structures can be neglected. Our results illustrate the power of multivalency to program the multicomponent self-assembly of specific entities into discrete functional nanostructures. PMID:26124877

  8. 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. PMID:25341502

  9. 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.

  10. 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

  11. Enantioselective Synthesis of 3,3-Difluoropyrrolidin-4-ol, a Valuable Building Block in Medicinal Chemistry.

    PubMed

    Si, Chong; Fales, Kevin R; Torrado, Alicia; Frimpong, Kwame; Kaoudi, Talbi; Vandeveer, Harold George; Njoroge, F George

    2016-05-20

    In this paper, we report for the first time two enantioselective routes to 4,4-difluoropyrrolidin-3-ol, a valuable building block in medicinal chemistry. In the first route, we took advantage of the C2 symmetry of (3R,4R)-3,4-dihydroxypyrrolidine in which the desired chirality was derived from the chiral pool (l-(+)-tartaric acid). In the second route, we efficiently assembled the pyrrolidine ring in the presence of a gem-difluoro moiety to avoid using potentially hazardous deoxofluorinating reagents and subsequently introduced the chirality by a stereoselective iridium-diamine-catalyzed asymmetric transfer hydrogenation reaction. PMID:27138111

  12. High-order accurate multi-phase simulations: building blocks and whats tricky about them

    NASA Astrophysics Data System (ADS)

    Kummer, Florian

    2015-11-01

    We are going to present a high-order numerical method for multi-phase flow problems, which employs a sharp interface representation by a level-set and an extended discontinuous Galerkin (XDG) discretization for the flow properties. The shape of the XDG basis functions is dynamically adapted to the position of the fluid interface, so that the spatial approximation space can represent jumps in pressure and kinks in velocity accurately. By this approach, the `hp-convergence' property of the classical discontinuous Galerkin (DG) method can be preserved for the low-regularity, discontinuous solutions, such as those appearing in multi-phase flows. Within the past years, several building blocks of such a method were presented: this includes numerical integration on cut-cells, the spatial discretization by the XDG method, precise evaluation of curvature and level-set algorithms tailored to the special requirements of XDG-methods. The presentation covers a short review on these building-block and their integration into a full multi-phase solver. A special emphasis is put on the discussion of the several pitfalls one may expire in the formulation of such a solver. German Research Foundation.

  13. Designing Organic Phosphine Oxide Host Materials Using Heteroaromatic Building Blocks: Inductive Effects on Electroluminescence

    SciTech Connect

    Sapochak, Linda S.; Padmaperuma, Asanga B.; Vecchi, Paul A.; Cai, Xiuyu; Burrows, Paul E.

    2007-11-19

    Phosphine oxide substitution of small molecules with high triplet exciton energies allows development of vacuum sublimable, electron transporting host materials for blue OLEDs. Heteroaromatic building blocks (carbazole, dibenzofuran and dibenzothiophene) with ET ~ 3 eV were incorporated into phosphine oxide (PO) structures. External quantum efficiencies (EQEs) at lighting brightness (i.e., 800 cd/m2) reached as high as 9.8% at 5.2V for OLEDs using the heteroaromatic PO hosts doped with the sky blue phosphor, iridium(III)bis(4,6-(di-fluorophenyl)-pyridinato-N,C2’) picolinate (FIrpic). Comparing device properties at a similar current density (i.e., J = 13 mA/cm2) showed the dibenzothiophene-bridged PO compound exhibits the highest EQEs and lowest operating voltages at all phosphor dopant levels. These results are explained with respect to the effects of the inductive phosphine oxide substituents on electrochemical, photophysical and electroluminescence properties of the substituted heteroaromatic building blocks.

  14. Conformation and orientation dependence in ion-induced collisions with DNA and RNA building blocks

    NASA Astrophysics Data System (ADS)

    Bacchus-Montabonel, Marie-Christine

    2015-04-01

    Action of radiations on biological tissues is of major concern in cancer therapy development. Understanding the mechanisms involved at the molecular level in such reactions may be of crucial interest. In particular ion-induced ionization processes appear at the early stage of damage and a detailed analysis has been performed on the charge transfer dynamics of carbon ions with the different DNA and RNA building blocks in order to analyze their respective behavior in ion-induced collisions. We have considered the pyrimidine nucleobases uracil and thymine and the 5-halouracil molecules corresponding to the same skeleton, as well as the sugar moiety 2-deoxy-D-ribose. The calculations have been performed by means of ab initio quantum chemistry molecular methods followed by a semi-classical collision treatment in a wide collision energy range. Considerations of the structure of the biological target as well as analysis of the anisotropy of the process have been performed. The comparison with proton collisions has been developed with regard to previous results. Qualitative trends of interest for DNA building blocks damage may be pointed out.

  15. 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. PMID:27273862

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

    PubMed

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

    2016-01-01

    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. PMID:26794242

  17. Surfactant-free CZTS nanoparticles as building blocks for low-cost solar cell absorbers

    NASA Astrophysics Data System (ADS)

    Zaberca, O.; Oftinger, F.; Chane-Ching, J. Y.; Datas, L.; Lafond, A.; Puech, P.; Balocchi, A.; Lagarde, D.; Marie, X.

    2012-05-01

    A process route for the fabrication of solvent-redispersible, surfactant-free Cu2ZnSnS4 (CZTS) nanoparticles has been designed with the objective to have the benefit of a simple sulfide source which advantageously acts as (i) a complexing agent inhibiting crystallite growth, (ii) a surface additive providing redispersion in low ionic strength polar solvents and (iii) a transient ligand easily replaced by an carbon-free surface additive. This multifunctional use of the sulfide source has been achieved through a fine tuning of ((Cu2+)a(Zn2+)b(Sn4+)c(Tu)d(OH-)e)t+, Tu = thiourea) oligomers, leading after temperature polycondensation and S2- exchange to highly concentrated (c > 100 g l-1), stable, ethanolic CZTS dispersions. The good electronic properties and low-defect concentration of the sintered, crack-free CZTSe films resulting from these building blocks was shown by photoluminescence investigation, making these building blocks interesting for low-cost, high-performance CZTSe solar cells.

  18. MOVIE: a hardware building block for software-only real-time video processing

    NASA Astrophysics Data System (ADS)

    Barzic, Ronan; Bouville, Christian; Charot, Francois; Le Fol, Gwendal; Lemonnier, Pascal; Wagner, Charles

    1996-03-01

    The goal of the MOVIE VLSI chip is to facilitate the development of software-only solutions for real time video processing applications. This chip can be seen as a building block for SIMD arrays of processing elements and its architecture has been designed so as to facilitate high level language programming. The basic architecture building block associates a sub-array of computational processors with a I/O processor. A module can be seen as a small linear, systolic-like array of processing elements, connected at each end to the I/O processor. The module can communicate with its two nearest neighbors via two communication ports. The chip architecture also includes three 16-bit video ports. One important aspect in the programming environment is the C-stolic programming language. C-stolic is a C-like language augmented with parallel constructs which allow to differentiate between the array controller variables (scalar variables) and the local variables in the array structure (systolic variables). A statement operating on systolic variables implies a simultaneous execution on all the cells of the structure. Implementation examples of MOVIE-based architectures dealing with video compression algorithms are given.

  19. Holographic optical tweezers: microassembling of shape-complementary 2PP building blocks

    NASA Astrophysics Data System (ADS)

    Ksouri, Sarah Isabelle; Mattern, Manuel; Köhler, Jannis; Aumann, Andreas; Zyla, Gordon; Ostendorf, Andreas

    2014-09-01

    Based on an ongoing trend in miniaturization and due to the increased complexity in MEMS-technology new methods of assembly need to be developed. Recent developments show that particularly optical forces are suitable to meet the requirements. The unique advantages of optical tweezers (OT) are attractive due to their contactless and precise manipulation forces. Spherical as well as non-spherical shaped pre-forms can already be assembled arbitrarily by using appropriate beam profiles generated by a spatial light modulator (SLM), resulting in a so called holographic optical tweezer (HOT) setup. For the fabrication of shape-complementary pre-forms, a two-photon-polymerization (2PP) process is implemented. The purpose of the process combination of 2PP and HOT is the development of an optical microprocessing platform for assembling arbitrary building blocks. Here, the optimization of the 2PP and HOT processes is described in order to allow the fabrication and 3D assembling of interlocking components. Results include the analysis of the dependence of low and high qualities of 2PP microstructures and their manufacturing accuracy for further HOT assembling processes. Besides, the applied detachable interlocking connections of the 2PP building blocks are visualized by an application example. In the long-term a full optical assembly method without applying any mechanical forces can thus be realized.

  20. Substrate-controlled linking of molecular building blocks: Au(111) vs. Cu(111)

    NASA Astrophysics Data System (ADS)

    Koch, Matthias; Gille, Marie; Viertel, Andreas; Hecht, Stefan; Grill, Leonhard

    2014-09-01

    The coupling of dibromohexabenzocoronene (Br2-HBC) as a precursor molecule is investigated by scanning tunneling microscopy (STM) on two noble metal surfaces: Au(111) and Cu(111). It is found that the on-surface polymerization of molecular building blocks equipped with halogen atoms is strongly influenced by the choice of the substrate. While on Au(111) a heating step of up to 520 K is required to activate the molecules and form polymers, on Cu(111) the catalytic reactivity causes activation already below room temperature. Due to the different substrates, the intramolecular bonds in the polymers between the HBC units differ: The HBC molecules are covalently coupled on Au(111) while on Cu(111) a copper adatom mediates the bonding. This effect is proven by the comparison with gas phase calculations and by lateral manipulation with the STM tip. The choice of the substrate thus does not only define the activation temperature but also lead to different bonding strengths between the molecular building blocks.

  1. 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

  2. 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

  3. Expanding the structural diversity of self-assembling dendrons and supramolecular dendrimers via complex building blocks.

    PubMed

    Percec, Virgil; Won, Betty C; Peterca, Mihai; Heiney, Paul A

    2007-09-12

    The design and synthesis of the first examples of AB4 and AB5 dendritic building blocks with complex architecture are reported. Structural and retrostructural analysis of supramolecular dendrimers self-assembled from hybrid dendrons based on different combinations of AB4 and AB5 building blocks with AB2 and AB3 benzyl ether dendrons demonstrated that none of these new hybrid dendrons exhibit the previously encountered conformations of libraries of benzyl ether dendrons. These hybrid dendrons enabled the discovery of some highly unusual tapered and conical dendrons generated by the intramolecular back-folding of their repeat units and of their apex. The new back-folded tapered dendrons have double thickness and self-assemble into pine-tree-like columns exhibiting a long-range 7/2 helical order. The back-folded conical dendrons self-assemble into spherical dendrimers. Non-back-folded truncated conical dendrons were also discovered. They self-assemble into spherical dendrimers with a less densely packed center. The discovery of dendrons displaying a novel crown-like conformation is also reported. Crown-like dendrons self-assemble into long-range 5/1 helical pyramidal columns. The long-range 7/2 and 5/1 helical structures were established by applying, for the first time, the helical diffraction theory to the analysis of X-ray patterns obtained from oriented fibers of supramolecular dendrimers. PMID:17705390

  4. Digitally programmable analog building blocks for the implementation of artificial neural networks.

    PubMed

    Almeida, A P; Franca, J E

    1996-01-01

    This paper describes the design, experimental characterization and behavior modeling of a homogeneous set of building blocks necessary to construct in analog hardware feed-forward artificial neural networks. A novel synapse architecture is proposed using a quasi-passive D/A (digital-to-analog) converter followed by a four-quadrant analog-digital multiplier, its main advantages are 1) increased signal input range; 2) improved area/weight resolution ratio; 3) on-chip refreshing of the weight value; and 4) serial loading the weight bits. The neurons are built using MOS (metal-oxide semiconductor) transistors operating in the saturation region and exploiting the inherent quadratic characteristics. Experimental results obtained from a demonstration prototype chip realized in a 1.2 mum double-poly, double-metal CMOS (complimentary MOS) technology show good agreement with the design specifications. A simple application of the proposed building blocks is illustrated based on the mixed-signal simulation of the corresponding behavior models constructed from the experimental characterization data. PMID:18255602

  5. Surfactant-free CZTS nanoparticles as building blocks for low-cost solar cell absorbers.

    PubMed

    Zaberca, O; Oftinger, F; Chane-Ching, J Y; Datas, L; Lafond, A; Puech, P; Balocchi, A; Lagarde, D; Marie, X

    2012-05-11

    A process route for the fabrication of solvent-redispersible, surfactant-free Cu₂ZnSnS₄ (CZTS) nanoparticles has been designed with the objective to have the benefit of a simple sulfide source which advantageously acts as (i) a complexing agent inhibiting crystallite growth, (ii) a surface additive providing redispersion in low ionic strength polar solvents and (iii) a transient ligand easily replaced by an carbon-free surface additive. This multifunctional use of the sulfide source has been achieved through a fine tuning of ((Cu²⁺)(a)(Zn²⁺)(b)(Sn⁴⁺)(c)(Tu)(d)(OH⁻)(e))(t⁺), Tu = thiourea) oligomers, leading after temperature polycondensation and S²⁻ exchange to highly concentrated (c > 100 g l⁻¹), stable, ethanolic CZTS dispersions. The good electronic properties and low-defect concentration of the sintered, crack-free CZTSe films resulting from these building blocks was shown by photoluminescence investigation, making these building blocks interesting for low-cost, high-performance CZTSe solar cells. PMID:22513652

  6. DNA induced chirality and helical twist in achiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Garvey, Alfred; Basu, Rajratan; Kinnamon, Daniel

    A small quantity of DNA sample (Deoxyribonucleic acid -cellulose double-stranded from calf thymus DNA in lyophilized powder form) was doped in an achiral liquid crystal (LC), and the mixture was found to exhibit a weak degree of chirality. The induced chirality in the LC was probed by means of the electroclinic effect in the LC's smectic-A phase, which showed significant pretransitional behavior on approaching the smectic- A-smectic- C transition temperature from above. The same DNA was doped in an achiral nematic LC and the mixture was found to exhibit an average mechanical twist over macroscopic dimensions. The double-stranded DNA-induced chiral pitch length P was determined by measuring the radius of curvature of reverse twist disclination lines in 90o nematic twist cells. In the LC +DNA mixture, the LC's benzene rings interact with the nucleobases of the DNA through π - π stacking, which induces a molecular conformational deracemization in the LC.

  7. 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. PMID:25309482

  8. Cosmic queuing: galaxy satellites, building blocks and the hierarchical clustering paradigm

    NASA Astrophysics Data System (ADS)

    Lagos, Claudia Del P.; Padilla, Nelson D.; Cora, Sofía A.

    2009-07-01

    We study the properties of building blocks (BBs; i.e. accreted satellites) and surviving satellites of present-day galaxies using the semi-analytic model of galaxy formation SAG (‘semi-analytic galaxies') in the context of a concordance Λ cold dark matter (ΛCDM) cosmology. We consider large number of dark matter (DM) halo merger trees spanning a wide range of masses (~1 × 1010-2.14 × 1015Msolar). We find higher metallicities for BBs with respect to surviving satellites, an effect produced by the same processes behind the build up of the mass-metallicity relation. We prove that these metallicity differences arise from the higher peak height in the density fluctuation field occupied by BBs and central galaxies which have collapsed into a single object earlier than surviving satellites. BBs start to form stars earlier, during the peak of the merger activity in ΛCDM, and build up half of their final stellar mass (measured at the moment of disruption) up to four times faster than surviving satellites. Surviving satellites keep increasing their stellar masses rather quiescently down to z ~= 1. The difference between the metallicities of satellites, BBs and central galaxies depends on the host DM halo mass, in a way that can be used as a further test for the concordance cosmology.

  9. 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. PMID:26970194

  10. 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

  11. Asymmetric Autocatalysis Induced by Chiral Crystals of Achiral Tetraphenylethylenes

    NASA Astrophysics Data System (ADS)

    Kawasaki, Tsuneomi; Nakaoda, Mai; Kaito, Nobuhiro; Sasagawa, Taisuke; Soai, Kenso

    2010-02-01

    The achiral hydrocarbon tetraphenylethylene crystallizes in enantiomorphous forms (chiral space group: P21) to afford right- and left-handed hemihedral crystals, which can be recognized by solid-state circular dichroism spectroscopic analysis. Chiral organic crystals of tetraphenylethylene mediated enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde to give, in conjunction with asymmetric autocatalysis with amplification of chirality, almost enantiomerically pure ( S)- and ( R)-5-pyrimidyl alkanols whose absolute configurations were controlled efficiently by the crystalline chirality of the tetraphenylethylene substrate. Tetrakis( p-chlorophenyl)ethylene and tetrakis( p-bromophenyl)ethylene also show chirality in the crystalline state, which can also act as a chiral substrate and induce enantioselectivity of diisopropylzinc addition to pyrimidine-5-carbaldehyde in asymmetric autocatalysis to give enantiomerically enriched 5-pyrimidyl alkanols with the absolute configuration correlated with that of the chiral crystals. Highly enantioselective synthesis has been achieved using chiral crystals composed of achiral hydrocarbons, tetraphenylethylenes, as chiral inducers. This chemical system enables significant amplification of the amount of chirality using spontaneously formed chiral crystals of achiral organic compounds as the seed for the chirality of asymmetric autocatalysis.

  12. A synthetic strategy to xylose-containing thioglycoside tri- and tetrasaccharide building blocks corresponding to Cryptococcus neoformans capsular polysaccharide structures.

    PubMed

    Guazzelli, Lorenzo; Ulc, Rebecca; Rydner, Lina; Oscarson, Stefan

    2015-06-21

    As part of an ongoing project aimed at developing vaccine candidates against Cryptococcus neoformans the preparation of tri- and tetrasaccharide thioglycoside building blocks, to be used in construction of structurally defined part structures of C. neoformans GXM capsular polysaccharide, was investigated. Using a naphthalenylmethyl (NAP) ether as a temporary protecting group and trichloroacetimidate donors in optimized glycosylations the target building blocks, ethyl 6-O-acetyl-2,4-di-O-benzyl-3-O-(2-naphthalenylmethyl)-α-D-mannopyranosyl-(1→3)-[2,3,4-tri-O-benzyl-β-D-xylopyranosyl-(1→2)]-4,6-di-O-benzyl-1-thio-α-D-mannopyranoside (16) and ethyl 2,3,4-tri-O-benzyl-β-D-xylopyranosyl-(1→2)-4,6-di-O-benzyl-3-O-(2-naphthalenylmethyl)-α-D-mannopyranosyl-(1→3)-[2,3,4-tri-O-benzyl-β-D-xylopyra-nosyl-(1→2)]-6-O-acetyl-4-O-benzyl-1-thio-α-D-mannopyranoside (21), were efficiently prepared. These synthesized thiosaccharide building blocks were then used as donors in high-yielding (~90%) DMTST promoted glycosylations to a spacer-containing acceptor to, after deprotection, afford GXM polysaccharide part structures ready for protein conjugation to give vaccine candidates. Also, the NAP groups in the building blocks were removed to obtain tri- and tetrasaccharide acceptors suitable for further elongation towards larger thiosaccharide building blocks. PMID:25986781

  13. Molecular Structures of the Products of a Diphosphonate Ester Building Block with Lewis Bases.

    PubMed

    Li, Yufeng; Jian, Fangfang

    2015-01-01

    By treating a suitable Wittig reagent under acid conditions, the phosphonate ester 1,4-bimethylenebenzene phosphonate ethyl ester (H2[BBPE], 1) was obtained. As a building block, compound 1 has been reacted with the Lewis-base N,N-dimethylpiperazine, ammonia and NaOH yielded compounds 2-4. The crystal structures show that a 1D chain forming a tubular channel is constructed through hydrogen bonds in 1; hydrogen bonds form two 1D chains with left-hand and right-hand helixes and form 3D networks in compound 2; 1D hydrogen-bond chains are further connected together to afford a 3D network architecture in compound 3; the phosphonate is coordinated by two Na atoms which present different coordination environments in compound 4. Additionally, the relationships between the structure and fluorescence of the four compounds in the solid state and in different solvents have also been studied at room temperature. PMID:26262606

  14. The Breaking and Mending of meso-Tetraarylporphyrins: Transmuting the Pyrrolic Building Blocks.

    PubMed

    Brückner, Christian

    2016-06-21

    Naturally occurring porphyrins and hydroporphyrins vary with respect to their ring substituents and oxidation states, but their tetrapyrrolic frameworks remain fully preserved across all kingdoms of life; there are no naturally occurring porphyrin-like macrocycles known that contain nonpyrrolic building blocks. However, the study of porphyrin analogues in which one or two pyrroles were replaced with nonpyrrolic building blocks might shed light on the correlation between structural modulation and ground and excited state optical properties of the "pigments of life", unlocking their mechanisms of function. Also, porphyrinoids with strong absorbance and emission spectra in the NIR are sought after in technical (e.g., light-harvesting) and biomedical (e.g., imaging and photochemotherapy) applications. These porphyrin analogues, the so-called pyrrole-modified porphyrins (PMPs), are synthetically accessible using total syntheses. Alternatively-and most handily-they can also be formed by conversion of synthetic porphyrins. Guided by older reports of the fortuitous modifications of porphyrins into PMPs, our research program generalized the so-dubbed "Breaking and Mending of Porphyrins" approach toward PMPs. This method to convert a pyrrole in meso-tetraarylporphyrins to a nonpyrrolic building block with high precision relies on a number of distinct steps. Step 1: The porphyrin is functionalized in a way that activates one or two peripheral double bonds toward breakage; in all cases surveyed here, this step is an osmium tetroxide-mediated dihydroxylation to generate dihydroxychlorin and tetrahydroxybacteriochlorins. Step 2: The activated, dihydroxylated β,β'-bond is "broken". Step 3: The functional groups resulting from the ring-cleavage reactions are utilized in subsequent "mending" steps to form the PMPs, that themselves may be subject to further modifications, Step 4. Thus, PMPs in which a pyrrole was degraded to an imine linkage, contracted to a four-membered ring, or

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

    PubMed

    Viero, Gabriella; Lunelli, Lorenzo; Passerini, Andrea; Bianchini, Paolo; Gilbert, Robert J; Bernabò, Paola; Tebaldi, Toma; Diaspro, Alberto; Pederzolli, Cecilia; Quattrone, Alessandro

    2015-03-01

    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

  16. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Injectable hydrogels can provide a scaffold for in situ tissue regrowth and regeneration, yet gel degradation before tissue reformation limits the gels' ability to provide physical support. Here, we show that this shortcoming can be circumvented through an injectable, interconnected microporous gel scaffold assembled from annealed microgel building blocks whose chemical and physical properties can be tailored by microfluidic fabrication. In vitro, cells incorporated during scaffold formation proliferated and formed extensive three-dimensional networks within 48 h. In vivo, the scaffolds facilitated cell migration that resulted in rapid cutaneous-tissue regeneration and tissue-structure formation within five days. The combination of microporosity and injectability of these annealed gel scaffolds should enable novel routes to tissue regeneration and formation in vivo.

  18. Price-Focused Analysis of Commercially Available Building Blocks for Combinatorial Library Synthesis.

    PubMed

    Kalliokoski, Tuomo

    2015-10-12

    Combinatorial libraries are synthesized by combining smaller reagents (building blocks), the price of which is an important component of the total costs associated with the synthetic exercise. A significant portion of commercially available reagents are too expensive for large scale work. In this study, 13 commonly used reagent classes in combinatorial library synthesis (primary and secondary amines, carboxylic acids, alcohols, ketones, aldehydes, boronic acids, acyl halides, sulfonyl chlorides, isocyanates, isothiocyanates, azides and chloroformates) were analyzed with respect to the cost, physicochemical properties (molecular weight and calculated logP), chemical diversity, and 3D-likeness using a large data set. The results define the chemical space accessible under a constraint of limited financial resources. PMID:26371511

  19. Alfvén wave collisions, the fundamental building block of plasma turbulence. IV. Laboratory experiment

    SciTech Connect

    Drake, D. J.; Schroeder, J. W. R.; Howes, G. G.; Kletzing, C. A.; Skiff, F.; Carter, T. A.; Auerbach, D. W.

    2013-07-15

    Turbulence is a phenomenon found throughout space and astrophysical plasmas. It plays an important role in solar coronal heating, acceleration of the solar wind, and heating of the interstellar medium. Turbulence in these regimes is dominated by Alfvén waves. Most turbulence theories have been established using ideal plasma models, such as incompressible MHD. However, there has been no experimental evidence to support the use of such models for weakly to moderately collisional plasmas which are relevant to various space and astrophysical plasma environments. We present the first experiment to measure the nonlinear interaction between two counterpropagating Alfvén waves, which is the building block for astrophysical turbulence theories. We present here four distinct tests that demonstrate conclusively that we have indeed measured the daughter Alfvén wave generated nonlinearly by a collision between counterpropagating Alfvén waves.

  20. 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.

  1. Replacement of the Disulfide Bridge in a KLK3-Stimulating Peptide Using Orthogonally Protected Building Blocks

    PubMed Central

    2013-01-01

    Peptide “B-2”, which is one of the most potent kallikrein-related peptidase 3 (KLK3)-stimulating compounds, consists of 12 amino acids and is cyclized by a disulfide bridge between the N- and C-terminal cysteines. Orthogonally protected building blocks were used in the peptide synthesis to introduce a disulfide bridge mimetic consisting of four carbon atoms. The resulting pseudopeptides with alkane and E-alkene linkers doubled the proteolytic activity of KLK3 at a concentration of 14 μM. They were almost as potent as the parent “B-2” peptide, which gives a 3.6-fold increase in the proteolytic activity of KLK3 at the same concentration. PMID:24900791

  2. 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. PMID:25714117

  3. Unique Curing Properties through Living Polymerization in Crosslinking Materials: Polyurethane Photopolymers from Vinyl Ether Building Blocks.

    PubMed

    Kirschbaum, Stefan; Landfester, Katharina; Taden, Andreas

    2015-05-01

    Photopolymers with unique curing capabilities were produced by combining living cationic polymerization with network formation and restricted polymer motion. A vinyl ether diol was synthesized as a functional building block and reacted with isophorone diisocyanate to form a highly functionalized vinyl ether polyurethane as a model system with high crosslinking ability. When using a cationic photoinitiator, fast polymerization is observed upon short UV irradiation. Curing proceeds in the absence of light and under ambient conditions without oxygen inhibition. Cationic active sites become trapped dormant species upon network-induced vitrification and surprisingly remain living for several days. The polymerization can be reactivated by additional UV irradiation and/or raised temperature. The curing behavior was studied in detail by using UV and FT-NIR coupled rheology and photo-DSC to simultaneously study spectroscopic and mechanical information, as well as thermal effects. PMID:25776255

  4. 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.

  5. 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

  6. Synthesis of a hybrid m-terphenyl/o-carborane building block: applications in phosphine ligand design.

    PubMed

    Lugo, Christopher A; Moore, Curtis E; Rheingold, Arnold L; Lavallo, Vincent

    2015-03-01

    A hybrid terphenyl/o-carborane ligand building block is synthesized by the reaction of m-terphenylalkyne with B10H14. This sterically demanding substituent can be installed into ligands, as demonstrated by the preparation of carboranylphosphine. The bulky phosphine reacts with [ClRh(CO)2]2 to produce monophosphine complex ClRhL(CO)2, which subsequently extrudes CO under vacuum to afford the dimeric species [ClRhL(CO)]2. The latter complex does not react with excess phosphine and is resistant toward cyclometalation, which is in contrast to related o-carborane phosphine complexes. Data from a single-crystal X-ray diffraction study are utilized to quantify the steric impact of the ligand via the percent buried volume approach. PMID:25668570

  7. The mesoscale convection life cycle: Building block or prototype for large-scale tropical waves?

    NASA Astrophysics Data System (ADS)

    Mapes, Brian; Tulich, Stefan; Lin, Jialin; Zuidema, Paquita

    2006-12-01

    A cumulonimbus cloud may ascend and spawn its anvil cloud, precipitation, and downdrafts within an hour or so. This paper inquires why a similar progression of events (life cycle) is observed for tropical weather fluctuations with time scales of hours, days, and even weeks. Regressions using point data illustrate the characteristic unit of rain production: the mesoscale convective system (MCS), covering tens of kilometers and lasting several hours, with embedded convective rain cells. Meanwhile, averages over larger spatial areas indicate a self-similar progression from shallow to deep convection to stratiform anvils on many time scales. Synthetic data exercises indicate that simple superpositions of fixed-structure MCS life cycles (the Building Block hypothesis) cannot explain why longer period life cycles are similar. Rather, it appears that an MCS may be a small analogue or prototype of larger scale waves. Multiscale structure is hypothesized to occur via a Stretched Building Block conceptual model, in which the widths (durations) of zones of shallow, deep, and stratiform anvil clouds in MCSs are modulated by larger scale waves. Temperature ( T) and humidity ( q) data are examined and fed into an entraining plume model, in an attempt to elucidate their relative roles in these large-scale convection zone variations. T profile variations, with wavelengths shorter than troposphere depth, appear important for high-frequency ( ˜ 2-5-day period) convectively coupled waves, as density directly links convection (via buoyancy) and large-scale wave dynamics (via restoring force). Still, the associated q anomalies are several times greater than adiabatic, suggesting a strong amplification by shallow convective feedbacks. For lower frequency (intraseasonal) variability, q anomalies are considerably larger compared to T, and may be dominant.

  8. Acetylene as an essential building block for prebiotic formation of pyrimidine bases on Titan.

    PubMed

    Jeilani, Yassin A; Fearce, Chelesa; Nguyen, Minh Tho

    2015-10-01

    Prebiotic building blocks for the formation of biomolecules are important in understanding the abiotic origin of biomolecules. However, there is a limited choice of the building blocks as precursors for the biomolecules. Acetylene (HCCH) is found in Titan's atmosphere and is an abiotic-precursor of pyrimidine bases. HCCH reacts with urea to form both cytosine and uracil. The mechanisms for the formation of both cytosine and uracil were studied by density functional theory at B3LYP/6-311G(d,p) level. Ethynyl radicals (˙CCH) are relevant for the chemistry of Titan's atmosphere therefore both HCCH and ˙CCH were evaluated as carbon sources. The pathways, for both HCCH and ˙CCH, lead to intermediates with an unsaturated-group that facilitate the formation of the six-membered ring of the pyrimidine bases. The predicted structures for cytosine and uracil were compared with labeled cytosine and uracil that were formed from the reaction of DCCD with urea. The results suggest that cytosine is formed from HCCH while uracil is formed from ˙CCH. The mechanisms are energetically feasible and there is no conclusive evidence for the preferred pathway (HCCH or ˙CCH). The pathways were further extended for the formation of both uric acid and 8-oxoguanine from HCCH and urea, and demonstrate the utility of HCCH as a carbon source for diverse biomolecules. Biuret is identified as a precursor for the pyridimine bases, and it unifies the free radical pathways for the pyrimidine bases with those of triazines. The pathways are appropriate for the reducing atmosphere that creates both radicals and electrons due to ionizing radiation on Titan. The mechanisms are feasible for the extraterrestrial formation of the pyrimidine bases. PMID:26325173

  9. Tracing the Archaeal Origins of Eukaryotic Membrane-Trafficking System Building Blocks.

    PubMed

    Klinger, Christen M; Spang, Anja; Dacks, Joel B; Ettema, Thijs J G

    2016-06-01

    In contrast to prokaryotes, eukaryotic cells are characterized by a complex set of internal membrane-bound compartments. A subset of these, and the protein machineries that move material between them, define the membrane-trafficking system (MTS), the emergence of which represents a landmark in eukaryotic evolution. Unlike mitochondria and plastids, MTS organelles have autogenous origins. Much of the MTS machinery is composed of building blocks, including small GTPase, coiled-coil, beta-propeller + alpha-solenoid, and longin domains. Despite the identification of prokaryotic proteins containing these domains, only few represent direct orthologues, leaving the origins and early evolution of the MTS poorly understood. Here, we present an in-depth analysis of MTS building block homologues in the composite genome of Lokiarchaeum, the recently discovered archaeal sister clade of eukaryotes, yielding several key insights. We identify two previously unreported Eukaryotic Signature Proteins; orthologues of the Gtr/Rag family GTPases, involved in target of rapamycin complex signaling, and of the RLC7 dynein component. We could not identify golgin or SNARE (coiled-coil) or beta-propeller + alpha-solenoid orthologues, nor typical MTS domain fusions, suggesting that these either were lost from Lokiarchaeum or emerged later in eukaryotic evolution. Furthermore, our phylogenetic analyses of lokiarchaeal GTPases support a split into Ras-like and Arf-like superfamilies, with different prokaryotic antecedents, before the advent of eukaryotes. While no GTPase activating proteins or exchange factors were identified, we show that Lokiarchaeum encodes numerous roadblock domain proteins and putative longin domain proteins, confirming the latter's origin from Archaea. Altogether, our study provides new insights into the emergence and early evolution of the eukaryotic membrane-trafficking system. PMID:26893300

  10. 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.

  11. 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. PMID:25362355

  12. 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.

  13. Smart Hydrogels with Inhomogeneous Structures Assembled Using Nanoclay-Cross-Linked Hydrogel Subunits as Building Blocks.

    PubMed

    Yao, Chen; Liu, Zhuang; Yang, Chao; Wang, Wei; Ju, Xiao-Jie; Xie, Rui; Chu, Liang-Yin

    2016-08-24

    A novel and facile assembly strategy has been successfully developed to construct smart nanocomposite (NC) hydrogels with inhomogeneous structures using nanoclay-cross-linked stimuli-responsive hydrogel subunits as building blocks via rearranged hydrogen bonding between polymers and clay nanosheets. The assembled thermoresponsive poly(N-isopropylacrylamide-co-acrylamide) (poly(NIPAM-co-AM)) hydrogels with various inhomogeneous structures exhibit excellent mechanical properties due to plenty of new hydrogen bonding interactions created at the interface for locking the NC hydrogel subunits, which are strong enough to tolerate external forces such as high levels of elongations and multicycles of swelling/deswelling operations. The proposed approach is featured with flexibility and designability to build assembled hydrogels with diverse architectures for achieving various responsive deformations, which are highly promising for stimuli-responsive manipulation such as actuation, encapsulation, and cargo transportation. Our assembly strategy creates new opportunities for further developing mechanically strong hydrogel systems with complex architectures that composed of diverse internal structures, multistimuli-responsive properties, and controllable shape deformation behaviors in the soft robots and actuators fields. PMID:27490585

  14. 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

    2016-03-01

    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. PMID:26902412

  15. 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.

  16. Building Quality Report Cards for Geriatric Care in The Netherlands: Using Concept Mapping to Identify the Appropriate "Building Blocks" from the Consumer's Perspective

    ERIC Educational Resources Information Center

    Groenewoud, A. Stef; van Exel, N. Job A.; Berg, Marc; Huijsman, Robbert

    2008-01-01

    Purpose: This article reports on a study to identify "building blocks" for quality report cards for geriatric care. Its aim is to present (a) the results of the study and (b) the innovative step-by-step approach that was developed to arrive at these results. Design and Methods: We used Concept Mapping/Structured Conceptualization to define the…

  17. 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

  18. Remote Enantioselection Transmitted by an Achiral Peptide Nucleic Acid Backbone

    NASA Technical Reports Server (NTRS)

    Kozlov, Igor A.; Orgel, Leslie E.; Nielsen, Peter E.

    2000-01-01

    short homochiral segment of DNA into a PNA helix could have guaranteed that the next short segment of DNA to be incorporated would have the same handedness as the first. Once two segments of the same handedness were present, the probability that a third segment would have the same handedness would increase, and so on. Evolution could then slowly dilute out the PNA part. This scenario would ultimately allow the formation of a chiral oligonucleotide by processes that are largely resistant to enantiomeric crossinhibition. It is important to note that the ligation of homochiral dinucleotides on a nucleic acid template would probably be at least as enantiospecific as the reaction that we have studied. The disadvantage of using chiral monomers as components of a replicating system arises from the difficulty of generating a first long homochiral template from a racemic mixture of monomers, although results of experiments designed to overcome this difficulty by employing homochiral tetramers have been reported.l l The probability of obtaining a homochiral n-mer from achiral substrates is approximately 1P-I if the nontemplate-directed extension of the primer is not enantioselective. Hence, it would be very hard to get started with a homochiral 40-mer, for example. No such difficulty exists in a scenario that originates with an achiral genetic material and in which the incorporation of very few chiral monomers in this achiral background gradually progresses towards homochirality. It seems possible that some PNA sequences could act as catalysts, analogous to ribozymes, even though PNA lacks clear metal binding sites. Although such catalysts could not be enantioselective, the incorporation of as few as two chiral nucleotides could then impose chiral specificity on the system. Furthermore, such patch chimeras could help to bridge the gap in catalytic potential between PNA and RNA, while guaranteeing enantioselectivity.

  19. Photoelectron spectroscopy of cluster anions: In search of building blocks for cluster-assembled materials

    NASA Astrophysics Data System (ADS)

    Grubisic, Andrej

    A combination of mass spectrometry, anion photoelectron spectroscopy and theory were employed to study the electronic, geometric and reactive properties of a number of different cluster systems. A special emphasis was placed on scouting for those particular cluster compositions that show signs of enhanced stability. Those clusters could potentially be used as building blocks of cluster-assembled materials. The studied systems include aluminum hydrides, lanthanide-silicon mixed cluster, platinum-lead clusters and Al13 -. Among aluminum hydrides an entire family of previously unknown closo-alanes with a general formula AlnHn+2 (4 ≤ n ≤ 8) had been discovered. They exhibit signs of substantial stability and are shown to follow the Wade's rule for closo-alanes (Chapter 3). In the studies of lanthanide-silicon, LnSin- (3 ≤ n ≤ 13) clusters, lanthanide atoms were observed to adopt low oxidation numbers even in the presence of a strongly interacting silicon environment. The implied limited participation of lanthanide atoms' f-electrons in bonding with the silicon stands in stark contrast to the d-electrons of the transition metal atoms. The result raises prospects for magnetic, silicon-based clusters (Chapter 4). A series of reactive studies of Al13- a well-known magic cluster, and Aln- cluster anions in general were conducted to better understand their size-specific behavior. Size-selective etching of Al11- and Al12- by NH3 has been attributed to a diminished barrier for conversion of a physisorbed precursor into the chemisorbed adduct in case of these two clusters. Al13- shows few signs of reactivity. The well-documented inertness of Al13- towards O 2 has been traced back to the triplet state of oxygen. Due to the need to conserve spin along the reaction coordinate, the number of viable reaction channels that have a low barrier is greatly reduced (Chapter 5). Lastly, a building block of a recently synthesized cluster-assembled material, (Pt Pb 12)2-, was studied

  20. Solvent dependent assembly of lanthanide metallacrowns using building blocks with incompatible symmetry preferences.

    PubMed

    Jankolovits, Joseph; Kampf, Jeff W; Pecoraro, Vincent L

    2014-07-21

    Solvent dependence in the assembly of coordination driven macrocycles is a poorly understood phenomenon. This work presents the solvent dependent assembly of 8 lanthanide metallacrowns (LnMCs) in solution using picoline hydroxamic acid (picHA), Zn(II), and Ln(III) ions. ESI-MS and single-crystal X-ray crystallography reveal the selective assembly of LnZn4(picHA)4(3+), LnZn5(picHA)5(3+), LnZn8(picHA)8(3+), LnZn12(picHA)12(3+), LnZn16(picHA)16(3+), Ln2Zn3(picHA)4(4+), Ln2Zn7-9(picHA)8-10, and Ln4Zn4-5(picHA)8-9 complexes in five different solvents. The coordination preferences of the hard Ln(III) ion and relatively soft Zn(II) ion dictate the solvent selectivity in this system. The LnMCs assemble with open or closed Zn(II) and/or Ln(III) coordination sites based on the behavior of the solvent as an ancillary ligand. This structural promiscuity is attributed to the symmetry incompatible building blocks, which generate assemblies with substantial geometric strain such that no clear thermodynamic minimum exists between the different LnMCs. These LnMCs assemble from a Zn5(picHA)4(2+) intermediate, which is monitored using (1)H NMR and ESI-MS to assess the stability of the complexes and possible assembly pathways based on kinetic considerations. LnMC assemblies that can be generated through central metal substitution reactions such as the LnZn4(picHA)4(3+), LnZn5(picHA)5(3+), and LnZn8(picHA)8(3+) effectively reach equilibrium after 24 h at room temperature. In contrast, LnMCs that must disrupt the Zn5L4(2+) structure to assemble, such as the LnZn16L16(3+), reach equilibrium after heating for 24 h at 65 °C. A pathway for LnMC assembly is presented where the Zn5L4(2+) is the key intermediate based on these reaction data and shared structural motifs in the complexes. These results correlate solvent dependent assembly to the building block geometry, highlighting synthetic approaches for generating novel complexes. PMID:24956137

  1. "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

  2. A trimer of dimers is the basic building block for human immunodeficiency virus-1 capsid assembly.

    PubMed

    Tsiang, Manuel; Niedziela-Majka, Anita; Hung, Magdeleine; Jin, Debi; Hu, Eric; Yant, Stephen; Samuel, Dharmaraj; Liu, Xiaohong; Sakowicz, Roman

    2012-06-01

    Human immunodeficiency virus-1 (HIV-1) capsid protein (CA) has become a target of antiviral drug design in recent years. The recognition that binding of small molecules to the CA protein can result in the perturbation of capsid assembly or disassembly has led to mathematical modeling of the process. Although a number of capsid assembly models have been developed using biophysical parameters of the CA protein obtained experimentally, there is currently no model of CA polymerization that can be practically used to analyze in vitro CA polymerization data to facilitate drug discovery. Herein, we describe an equilibrium model of CA polymerization for the kinetic analysis of in vitro assembly of CA into polymer tubes. This new mathematical model has been used to assess whether a triangular trimer of dimers rather than a hexagonal hexamer can be the basic capsomere building block of CA polymer. The model allowed us to quantify for the first time the affinity for each of the four crucial interfaces involved in the polymerization process and indicated that the trimerization of CA dimers is a relatively slow step in CA polymerization in vitro. For wild-type CA, these four interfaces include the interface between two monomers of a CA dimer (K(D) = 6.6 μM), the interface between any two dimers within a CA trimer of dimers (K(D) = 32 nM), and two types of interfaces between neighboring trimers of dimers, either within the same ring around the perimeter of the polymer tube (K(D) = 438 nM) or from two adjacent rings (K(D) = 147 nM). A comparative analysis of the interface dissociation constants between wild-type and two mutant CA proteins, cross-linked hexamer (A14C/E45C/W184A/M185A) and A14C/E45C, yielded results that are consistent with the trimer of dimers with a triangular geometry being the capsomere building block involved in CA polymer growth. This work provides additional insights into the mechanism of HIV-1 CA assembly and may prove useful in elucidating how small

  3. Non-spherical zinc sulfide colloids as building blocks for three-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Liddell, Chekesha Miata

    The production of monodispersed non-spherical particles is necessary to fully explore the promise of colloidal systems for optical pigments, diffractive elements in smart sensors, and for photonic crystal applications. In the case of photonic crystals, the addition of asymmetry in the lattice enables photonic band gap realization at refractive index values insufficient for assemblies of monodispersed spheres. Additionally, complex building blocks lower the filling fraction of high index material due to geometric packing restrictions so that inverting the structures may not be required. In this work, a route to the production of non-spherical zinc sulfide particles was developed and evaluated for photonic crystal applications. Monodispersed ZnS clusters of close-packed shapes including dimers, trimers, tetramers and tetrahedra were synthesized by two-stage chemical precipitation, starting from homogeneous solutions of metal salt and thioacetamide sulfide ion precursor. The non-spherical particles are hierarchically structured, composed of 500nm--3mum coagulated monodispersed spheres, which are themselves aggregates of 5--10nm single crystal spheroids. Though the particles were porous, the index of refraction was high, n ˜ 2.2, as compared with silica and polystyere, n ˜ 1.5. The mixtures of morphological types synthesized were quantitatively analyzed by image analysis and stereology as well as flow cytometry. The estimated yield of dimers was 23vol%, having average size 1.29 microns and polydispersity 5.67%, well within the requirements for self-assembly. The dimers were obtained in large quantities, ˜1012, for harvesting and use in photonic crystal applications. Techniques such as flow cytometry were explored and may be promising for the separation and collection of the particle populations. Though the production of monodispersed ZnS spheres by the decomposition of thioacetamide has been utilized by other groups, this is the first report of their controlled

  4. DNA interstrand crosslinking agents: synthesis, DNA interactions, and cytotoxicity of dimeric achiral seco-amino-CBI and conjugates of achiral seco-amino-CBI with pyrrolobenzodiazepine (PBD).

    PubMed

    Purnell, Bethany; Sato, Atsushi; O'kelley, Amanda; Price, Carly; Summerville, Kaitlin; Hudson, Stephen; O'hare, Caroline; Kiakos, Konstantinos; Asao, Tetsuji; Lee, Moses; Hartley, John A

    2006-11-01

    The design and synthesis of three novel bisalkylating agents derived from the achiral seco-duocarmycin or CC-1065 analogs and pyrrolobenzodiazepines (PBDs) are described: achiral seco-CBI (cyclopropanebenz[e]indoline)-PBD 11, achiral seco-CI-PBD 12, and achiral seco-CBI dimer 13. Compounds 11 and 12 demonstrated enhanced cytotoxicity over the monomer counterparts against the growth of P815 murine mastocytoma cells in culture. Conjugate 11 was found to covalently react with adenine-N3 positions within the minor groove at AT-rich sequences and to produce DNA interstrand crosslinks. Both compounds were found to induce apoptosis in P815 cells. Due to its poor water solubility, dimer 13 did not give any appreciable DNA binding or cytotoxicity. PMID:16919946

  5. 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.…

  6. General, Highly Selective Synthesis of 1,3- and 1,4-Difunctionalized Building Blocks by Regiodivergent Epoxide Opening.

    PubMed

    Funken, Nico; Mühlhaus, Felix; Gansäuer, Andreas

    2016-09-19

    We describe a regiodivergent epoxide opening (REO) featuring a catalyst-controlled synthesis of enantiomerically and diastereomerically highly enriched or pure syn- and anti- 1,3- and 1,4-difunctionalized building blocks from a common epoxide precursor. The REO is attractive for natural product synthesis and as a branching reaction for diversity-oriented synthesis with epoxides. PMID:27600090

  7. Word Roots: Learning the Building Blocks of Better Spelling and Vocabulary. Level B, Book 1 [Grades 7-12].

    ERIC Educational Resources Information Center

    Blanchard, Cherie

    This workbook is designed to help secondary-school students expand their spelling, vocabulary, and comprehension skills through the study of roots, prefixes, and suffixes. Noting that roots, prefixes, and suffixes are the building blocks upon which all words are formed, the introduction contends that a thorough knowledge of these elements will…

  8. Word Roots: Learning the Building Blocks of Better Spelling and Vocabulary. Level A, Book 1 [Grades 4-6].

    ERIC Educational Resources Information Center

    Blanchard, Cherie

    This workbook is designed to help students expand their spelling, vocabulary, and comprehension skills through the study of roots, prefixes, and suffixes. Noting that roots, prefixes, and suffixes are the building blocks upon which all words are formed, the introduction contends that a thorough knowledge of these elements will greatly enhance…

  9. A two-dimensional homospin Cu(II) ferrimagnet featuring S-shaped hexanuclear secondary building blocks.

    PubMed

    Chen, Zilu; Liu, Long; Wang, Yifei; Zou, Huahong; Zhang, Zhong; Liang, Fupei

    2014-06-14

    The decomposition of 2-(1-hydroxy-2-methylpropan-2-yl-imino)-1,2-diphenylethanone in the presence of copper acetate promoted the formation of a two-dimensional homospin Cu(II) ferrimagnet featuring S-shaped hexanuclear secondary building blocks and a new pentanodal topology. PMID:24676556

  10. Paraelectric-antiferroelectric phase transition in achiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Pociecha, Damian; Gorecka, Ewa; Čepič, Mojca; Vaupotič, Nataša; Gomola, Kinga; Mieczkowski, Jozef

    2005-12-01

    Critical freezing of molecular rotation in an achiral smectic phase, which leads to polar ordering through the second order paraelectric-antiferroelectric (Sm-A→Sm-APA) phase transition is studied theoretically and experimentally. Strong softening of the polar mode in the Sm-A phase and highly intensive dielectric mode in the Sm-APA phase are observed due to weak antiferroelectric interactions in the system. In the Sm-APA phase the dielectric response behaves critically upon biasing by a dc electric field. Such a behavior is found general for the antiferroelectric smectic phase with significant quadrupolar interlayer coupling.

  11. 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.

  12. The building blocks of Earth and Mars: A close genetic link

    NASA Astrophysics Data System (ADS)

    Fitoussi, Caroline; Bourdon, Bernard; Wang, Xueying

    2016-01-01

    The Earth formed in a swarm of Moon- to Mars-sized objects that collided together to build our planet. A large body of work has been dedicated to understanding the Earth's composition as being made of single groups or mixtures of chondrites, however, these models cannot account for the isotopic and elemental characteristics of the Earth. Here, we test mixtures of meteorites, including achondrites, analyzed for seven isotope systems (O, Cr, Ni, Ti, Mo, Ca and Sr), to reproduce the isotope compositions of the Earth and Mars. Our Monte Carlo inversion (a numerical method based on generation of random numbers used to invert multiparameter models) yields a new compositional model where Earth and Mars come almost entirely from the same source material. This finding is in striking agreement with recent planetary formation models in which Earth and Mars formed in a common narrow zone of the protoplanetary disk with Mars being ejected to its current position which prevented further accretion. An important outcome of the model is that a significant mass fraction of the Earth could have been made of volatile depleted and refractory enriched planetary bodies such as angrites (among the oldest known achondrites). This conclusion is also in agreement with new Si isotope data in angrites which suggest that a component of angrites would help explain the difference in δ30 Si between the bulk silicate Earth and its building blocks. Our model matches all isotope compositions for both planets, reproduces the volatile element budget of Mars, and accounts for the enrichment in refractory elements of the Earth and Mars compared to chondrites.

  13. Inversion of the Supramolecular Chirality of Nanofibrous Structures through Co-Assembly with Achiral Molecules.

    PubMed

    Liu, Guo-Feng; Zhu, Ling-Yun; Ji, Wei; Feng, Chuan-Liang; Wei, Zhi-Xiang

    2016-02-12

    To understand the behavior of chiral nanostructures, it is of critical importance to study how achiral molecules regulate the chirality of such nanostructures and what the main driving forces for the regulation processes are. In this work, the supramolecular chirality of helical nanofibers consisting of phenylalanine-based enantiomers is inverted by achiral bis(pyridinyl) derivatives through co-assembly. This inversion is mainly mediated by intermolecular hydrogen bonding interactions between the achiral additives and the chiral molecules, which may induce stereoselective interactions and different reorientations for the assembled molecules, as confirmed by calculations. This work not only exemplifies a feasible method to invert the helicity of chiral nanostructures by the addition of achiral molecules, but also provides a method to explore their functions in environments where chiral and achiral molecules are in close proximity. PMID:26663528

  14. 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.

  15. Tailoring a bacteriochlorin building block with cationic, amphipathic, or lipophilic substituents.

    PubMed

    Ruzié, Christian; Krayer, Michael; Balasubramanian, Thiagarajan; Lindsey, Jonathan S

    2008-08-01

    Bacteriochlorins are attractive candidates for photodynamic therapy (PDT) of diverse medical indications owing to their strong absorption in the near-infrared (NIR) region, but their use has been stymied by lack of access to stable, synthetically malleable molecules. To overcome these limitations, a synthetic free base 3,13-dibromobacteriochlorin (BC-Br(3)Br(13)) has been exploited as a building block in the synthesis of diverse bacteriochlorins via Pd-mediated coupling reactions (Sonogashira, Suzuki, and reductive carbonylation). Each bacteriochlorin is stable to adventitious dehydrogenation by virtue of the presence of a geminal dimethyl group in each pyrroline ring. The target bacteriochlorins bear cationic, lipophilic, or amphipathic substituents at the 3- and 13- (beta-pyrrolic) positions. A dicarboxybacteriochlorin was converted to amide derivatives via the intermediate diacid chloride. A diformylbacteriochlorin was subjected to reductive amination to give aminomethyl derivatives. A set of 3,5-disubstituted aryl groups bearing lipophilic or amphipathic groups was introduced via Suzuki coupling. Altogether 22 free base bacteriochlorins have been prepared. Eight aminoalkylbacteriochlorins were quaternized with methyl iodide at two or four amine sites per molecule, which resulted in water solubility. Each bacteriochlorin exhibits a Q(y) absorption band in the range of 720-772 nm. The ability to introduce a wide variety of peripheral functional groups makes these bacteriochlorins attractive candidates for diverse applications in photomedicine including PDT in the NIR region. PMID:18576691

  16. 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.

  17. 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

  18. 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. PMID:19650106

  19. Aliphatic hyperbranched polyester: A new building block in the construction of multifunctional nanoparticles and nanocomposites**

    PubMed Central

    Santra, Santimukul; Kaittanis, Charalambos; Perez, J. Manuel

    2009-01-01

    Herein we report the design and synthesis of multifunctional hyperbranched polyester-based nanoparticles and nanocomposites with properties ranging from magnetic, fluorescence, antioxidant and X-ray contrast. The fabrication of these nanostructures was achieved using a novel aliphatic and biodegradable hyperbranched polyester (HBPE) synthesized from readily available diethylmalonate. The polymer’s globular structure with functional surface carboxylic groups and hydrophobic cavities residing in the polymer’s interior allows for the formation of multifunctional polymeric nanoparticles, which are able to encapsulate a diversity of hydrophobic cargos. Via simple surface chemistry modifications, the surface carboxylic acid groups were modified to yield nanoparticles with a variety of surface functionalizations, such as amino, azide and propargyl groups, which mediated the conjugation of small molecules. This capability achieved the engineering of the HBPE nanoparticle surface for specific cell internalization studies and the formation of nanoparticle assemblies for the creation of novel nanocomposites that retained, and in some cases enhanced, the properties of the parental nanoparticle building blocks. Considering these results, the HBPE polymer, nanoparticles and composites should be ideal for biomedical, pharmaceutical, nanophotonics and material applications. PMID:19957939

  20. 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.

  1. 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. PMID:19940920

  2. 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.

  3. Novel layered two-dimensional semiconductors as the building blocks for nano-electronic/photonic systems

    NASA Astrophysics Data System (ADS)

    Su, Guoxiong; De, Debtanu; Hadjiev, Viktor G.; Peng, Haibing

    2014-06-01

    Layered two-dimensional (2D) semiconductors beyond graphene have been emerging as potential building blocks for the next-generation electronic/photonic applications. Representative metal chalcogenides, including the widely studied MoS2, possess similar layered crystal structures with weak interaction between adjacent layers, thus allowing the formation of stable thin-layer crystals with thickness down to a few or even single atomic layer. Other important chalcogenides, involving earth-abundant and environment-friendly materials desirable for sustainable applications, include SnS2 (band gap: 2.1 eV) and SnS (band gap: 1.1 eV). So far, commonly adopted for research purpose are mechanical and liquid exfoliation methods for creating thin layers of such 2D semiconductors. Most recently, chemical vapor deposition (CVD) was attracting significant attention as a practical method for producing thin films or crystal grains of MoS2. However, critical yet still absent is an effective experimental approach for controlling the positions of thin crystal grains of layered 2D semiconductors during the CVD process. Here we report the controlled CVD synthesis of thin crystal arrays of representative layered semiconductors (including SnS2 and SnS) at designed locations on chip, promising large-scale optoelectronic applications. Our work opens a window for future practical applications of layered 2D semiconductors in integrated nano-electronic/photonic systems.

  4. 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. PMID:26829055

  5. Ultrahigh-speed rotating nanoelectromechanical system devices assembled from nanoscale building blocks

    NASA Astrophysics Data System (ADS)

    Kim, Kwanoh; Xu, Xiaobin; Guo, Jianhe; Fan, D. L.

    2014-04-01

    The development of rotary nanomotors is crucial for advancing nanoelectromechanical system technology. In this work, we report design, assembly and rotation of ordered arrays of nanomotors. The nanomotors are bottom-up assembled from nanoscale building blocks with nanowires as rotors, patterned nanomagnets as bearings and quadrupole microelectrodes as stators. Arrays of nanomotors rotate with controlled angle, speed (over 18,000 r.p.m.), and chirality by electric fields. Using analytical modelling, we reveal the fundamental nanoscale electrical, mechanical and magnetic interactions in the nanomotor system, which excellently agrees with experimental results and provides critical understanding for designing metallic nanoelectromechanical systems. The nanomotors can be continuously rotated for 15 h over 240,000 cycles. They are applied for controlled biochemical release and demonstrate releasing rate of biochemicals on nanoparticles that can be precisely tuned by mechanical rotations. The innovations reported in this research, from concept, design and actuation to application, are relevant to nanoelectromechanical system, nanomedicine, microfluidics and lab-on-a-chip architectures.

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

    PubMed

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

    2016-05-27

    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 [Formula: see text] 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 ([Formula: see text] = 0.99 Å(-1)) and through-space ([Formula: see text] = 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. PMID:27087356

  7. Electronic and optical excitations in building blocks of the metal organic framework MOF-5

    NASA Astrophysics Data System (ADS)

    Shi, Bin; Hung, Linda; Yildirim, Taner; Ogut, Serdar

    Metal organic frameworks (MOFs) are a relatively new class of materials which are made of metal-oxide clusters linked by organic bridging ligands. In recent years, MOFs have received considerable attention due to their widely tunable structural, chemical and physical properties. We investigate one of the well characterized MOFs, MOF-5, whose framework consists of tetrahedral [Zn40]6+ units linked by rigid arylcarboxylate ligands. We use many-body perturbation (GW +BSE) and time-dependent DFT methods in real space to examine the electronic and optical excitations in the building blocks of MOF-5, such as Zn4O(COOH)6, basic zinc acetate [Zn4O(CH3COO)6], and tetranuclear zinc benzoate [Zn4O(C6H5COO)6]. The calculated spectra are compared with available experimental measurements and existing calculations to shed light on the controversy regarding the nature (metal-ligand versus ligand-ligand) of low-energy electronic and optical excitations in MOF-5. Supported by DOE Grant No. DE-SC0001853.

  8. Stepwise Transformation of the Molecular Building Blocks in a Porphyrin-Encapsulating Metal-Organic Material

    SciTech Connect

    Zhang, Zhenjie; Wojtas, Lukasz; Eddaoudi, Mohamed; Zaworotko, Michael J.

    2013-06-05

    When immersed in solutions containing Cu(II) cations, the microporous metal–organic material P11 ([Cd4(BPT)4]·[Cd(C44H36N8)(S)]·[S], BPT = biphenyl-3,4',5-tricarboxylate) undergoes a transformation of its [Cd2(COO)6]2– molecular building blocks (MBBs) into novel tetranuclear [Cu4X2(COO)6(S)2] MBBs to form P11-Cu. The transformation occurs in single-crystal to single-crystal fashion, and its stepwise mechanism was studied by varying the Cd2+/Cu2+ ratio of the solution in which crystals of P11 were immersed. P11-16/1 (Cd in framework retained, Cd in encapsulated porphyrins exchanged) and other intermediate phases were thereby isolated and structurally characterized. P11-16/1 and P11-Cu retain the microporosity of P11, and the relatively larger MBBs in P11-Cu permit a 20% unit cell expansion and afford a higher surface area and a larger pore size.

  9. DNA-conducting polymer complexes: a computational study of the hydrogen bond between building blocks.

    PubMed

    Zanuy, David; Aleman, Carlos

    2008-03-13

    Ab initio quantum mechanical calculations at the MP2 level were used for an extensive study concerning the stability of hydrogen-bonded complexes formed by pyrrole and thiophene, which are the most common building blocks of conducting polymers, and DNA bases. Results indicated that very stable complexes were formed with pyrrole, which shows a clear tendency to form specific hydrogen-bonding interactions with nucleic acid bases. Furthermore, the strength of such interactions depends significantly on the base, growing in the following order: thymine < adenine approximately equal to cytosine < guanine. On the contrary, thiophene formed complexes stabilized by nonspecific interactions between the pi-cloud of the ring and the N-H groups of the nucleic acid bases rather than specific hydrogen bonds. Overall, these results are fully consistent with experimental observations: polypyrrole is able not only to stabilize adducts with DNA but also to interact specifically, while the interactions of the latter with polythiophene and their derivatives are weaker and nonspecific. PMID:18278905

  10. Inductive linkage identification on building blocks of different sizes and types

    NASA Astrophysics Data System (ADS)

    Chen, Ying-ping; Chuang, Chung-Yao; Huang, Yuan-Wei

    2012-12-01

    The goal of linkage identification is to obtain the dependencies among decision variables. Such information or knowledge can be applied to design crossover operators and/or the encoding schemes in genetic and evolutionary methods. Thus, promising sub-solutions to the problem will be disrupted less likely, and successful convergence may be achieved more likely. To obtain linkage information, a linkage identification technique, called Inductive Linkage Identification (ILI), was proposed recently. ILI was established upon the mechanism of perturbation and the idea of decision tree learning. By constructing a decision tree according to decision variables and fitness difference values, the interdependent variables will be determined by the adopted decision tree learning algorithm. In this article, we aim to acquire a better understanding on the characteristics of ILI, especially its behaviour under problems composed of different-sized and different-type building blocks (BBs) which are not overlapped. Experiments showed that ILI can efficiently handle BBs of different sizes and is insensitive to BB types. Our experimental observations indicate the flexibility and the applicability of ILI on various elementary BB types that are commonly adopted in related experiments.

  11. 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.

  12. The building blocks of planets within the 'terrestrial' region of protoplanetary disks.

    PubMed

    van Boekel, R; Min, M; Leinert, Ch; Waters, L B F M; Richichi, A; Chesneau, O; Dominik, C; Jaffe, W; Dutrey, A; Graser, U; Henning, Th; de Jong, J; Köhler, R; de Koter, A; Lopez, B; Malbet, F; Morel, S; Paresce, F; Perrin, G; Preibisch, Th; Przygodda, F; Schöller, M; Wittkowski, M

    2004-11-25

    Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates, yet crystalline silicates are abundant throughout the Solar System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates.) Little is known about the evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any terrestrial planets are formed, consistent with the composition of meteorites in the Solar System. PMID:15565147

  13. Nanopatterned graphene quantum dots as building blocks for quantum cellular automata

    NASA Astrophysics Data System (ADS)

    Wang, Z. F.; Liu, Feng

    2011-10-01

    Quantum cellular automata (QCA) is an innovative approach that incorporates quantum entities in classical computation processes. Binary information is encoded in different charge states of the QCA cells and transmitted by the inter-cell Coulomb interaction. Despite the promise of QCA, however, it remains a challenge to identify suitable building blocks for the construction of QCA. Graphene has recently attracted considerable attention owing to its remarkable electronic properties. The planar structure makes it feasible to pattern the whole device architecture in one sheet, compatible with the existing electronics technology. Here, we demonstrate theoretically a new QCA architecture built upon nanopatterned graphene quantum dots (GQDs). Using the tight-binding model, we determine the phenomenological cell parameters and cell-cell response functions of the GQD-QCA to characterize its performance. Furthermore, a GQD-QCA architecture is designed to demonstrate the functionalities of a fundamental majority gate. Our results show great potential in manufacturing high-density ultrafast QCA devices from a single nanopatterned graphene sheet.

  14. 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.

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

    PubMed

    Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2014-09-01

    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. PMID:25042025

  16. 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. PMID:22512717

  17. Can Fluorinated Molecular Cages Be Utilized as Building Blocks of Hyperhalogens?

    PubMed

    Sun, Wei-Ming; Li, Xiang-Hui; Li, Ying; Wu, Di; Li, Chun-Yan; Chen, Jing-Hua; Li, Zhi-Ru

    2016-05-18

    Based on the density functional theory for exchange-correlation potential, fluorocarbon molecular cages are investigated as building blocks of hyperhalogens. By utilizing C8 F7 as a ligand, a series of hyperhalogen anions, that is, M(C8 F7 )2 (-) (M=Li, Na, and K) and M(C8 F7 )3 (-) (M=Be, Mg, and Ca), are modeled. Calculations show that all the C8 F7 moieties preserve their geometric and electronic integrity in these anions. These anionic molecules possess larger vertical electron detachment energies (5.11-6.45 eV) than that of C8 F7 (-) , verifying their hyperhalogen nature. Moreover, it is also revealed that using larger fluorinated cage C10 F9 as ligands can bring about hyperhalogen anions with larger vertical electron detachment energies. The stability of these studied anions is determined by their large HOMO-LUMO gaps and positive dissociation energies of predetermined possible fragmentation pathways. It is hoped this study will provide an approach for the construction of new types of hyperhalogens and stimulate more research in superatom chemistry. PMID:26923480

  18. Heat-transport mechanisms in molecular building blocks of inorganic/organic hybrid superlattices

    NASA Astrophysics Data System (ADS)

    Giri, Ashutosh; Niemelä, Janne-Petteri; Tynell, Tommi; Gaskins, John T.; Donovan, Brian F.; Karppinen, Maarit; Hopkins, Patrick E.

    2016-03-01

    Nanomaterial interfaces and concomitant thermal resistances are generally considered as atomic-scale planes that scatter the fundamental energy carriers. Given that the nanoscale structural and chemical properties of solid interfaces can strongly influence this thermal boundary conductance, the ballistic and diffusive nature of phonon transport along with the corresponding phonon wavelengths can affect how energy is scattered and transmitted across an interfacial region between two materials. In hybrid composites composed of atomic layer building blocks of inorganic and organic constituents, the varying interaction between the phononic spectrum in the inorganic crystals and vibronic modes in the molecular films can provide a new avenue to manipulate the energy exchange between the fundamental vibrational energy carriers across interfaces. Here, we systematically study the heat transfer mechanisms in hybrid superlattices of atomic- and molecular-layer-grown zinc oxide and hydroquinone with varying thicknesses of the inorganic and organic layers in the superlattices. We demonstrate ballistic energy transfer of phonons in the zinc oxide that is limited by scattering at the zinc oxide/hydroquinone interface for superlattices with a single monolayer of hydroquinone separating the thicker inorganic layers. The concomitant thermal boundary conductance across the zinc oxide interfacial region approaches the maximal thermal boundary conductance of a zinc oxide phonon flux, indicative of the contribution of long wavelength vibrations across the aromatic molecular monolayers in transmitting energy across the interface. This transmission of energy across the molecular interface decreases considerably as the thickness of the organic layers are increased.

  19. Manipulation of partially oriented hydroxyapatite building blocks to form flowerlike bundles without acid-base regulation.

    PubMed

    Wen, Zhenliang; Wang, Zihao; Chen, Jingdi; Zhong, Shengnan; Hu, Yimin; Wang, Jianhua; Zhang, Qiqing

    2016-06-01

    The application of hydroxyapatite (HAP) in different fields depends greatly on its morphology, composition and structure. Besides, the main inorganic building blocks of human bones and teeth are also HAP. Therefore, accurate shape and aggregation control and of hydroxyapatite particles will be of great interest. Herein, oriented bundles of flowerlike HAP nanorods were successfully prepared through hydrothermal treatment without acid-base regulation, with the mono-alkyl phosphate (MAP) and sodium citrate as surfactant and chelating agent, respectively. The prepared samples were characterized by the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and zeta potential, the pH value and conductivity value of suspension were characterized by pH meter and conductivity measurement. The results showed that the MAP and citrate play an important role in assembly of HAP nanorods without acid-base regulation. Citrate calcium complex could decompose slowly and release citrate ions at hydrothermal conditions. Besides, the further decomposition of citrate ions could release aconitic acid as the reaction time prolongs. Moreover, the possible scheme for the formation process was discussed in detail. PMID:26930036

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

    PubMed

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

    2010-03-01

    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. PMID:20203604

  1. 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. PMID:25920010

  2. Thieno[3,4-c]phosphole-4,6-dione: A Versatile Building Block for Phosphorus-Containing Functional π-Conjugated Systems.

    PubMed

    Takeda, Youhei; Hatanaka, Kota; Nishida, Takuya; Minakata, Satoshi

    2016-07-18

    A versatile phosphorus-containing π-conjugated building block, thieno[3,4-c]phosphole-4,6-dione (TPHODO), has been developed. The utility of this simple but hitherto unknown building block has been demonstrated by preparing novel functional organophosphorus compounds and bandgap-tunable conjugated polymers. PMID:27213480

  3. Are ancient dwarf satellites the building blocks of the Galactic halo?

    NASA Astrophysics Data System (ADS)

    Spitoni, E.; Vincenzo, F.; Matteucci, F.; Romano, D.

    2016-05-01

    According to the current cosmological cold dark matter paradigm, the Galactic halo could have been the result of the assemblage of smaller structures. Here we explore the hypothesis that the classical and ultra-faint dwarf spheroidal satellites of the Milky Way have been the building blocks of the Galactic halo by comparing their [α/Fe] and [Ba/Fe] versus [Fe/H] patterns with the ones observed in Galactic halo stars. The α elements deviate substantially from the observed abundances in the Galactic halo stars for [Fe/H] values larger than -2 dex, while they overlap for lower metallicities. On the other hand, for the [Ba/Fe] ratio, the discrepancy is extended at all [Fe/H] values, suggesting that the majority of stars in the halo are likely to have been formed in situ. Therefore, we suggest that [Ba/Fe] ratios are a better diagnostic than [α/Fe] ratios. Moreover, for the first time we consider the effects of an enriched infall of gas with the same chemical abundances as the matter ejected and/or stripped from dwarf satellites of the Milky Way on the chemical evolution of the Galactic halo. We find that the resulting chemical abundances of the halo stars depend on the assumed infall time-scale, and the presence of a threshold in the gas for star formation. In particular, in models with an infall time-scale for the halo around 0.8 Gyr coupled with a threshold in the surface gas density for the star formation (4 M⊙ pc-2), and the enriched infall from dwarf spheroidal satellites, the first halo stars formed show [Fe/H]>-2.4 dex. In this case, to explain [α/Fe] data for stars with [Fe/H]<-2.4 dex, we need stars formed in dSph systems.

  4. 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. PMID:26437679

  5. 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.

  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. Triazole: a unique building block for the construction of functional materials.

    PubMed

    Juríček, Michal; Kouwer, Paul H J; Rowan, Alan E

    2011-08-21

    Over the past 50 years, numerous roads towards carbon-based materials have been explored, all of them being paved using mainly one functional group as the brick: acetylene. The acetylene group, or the carbon-carbon triple bond, is one of the oldest and simplest functional groups in chemistry, and although not present in any of the naturally occurring carbon allotropes, it is an essential tool to access their synthetic carbon-rich family. In general, two strategies towards the synthesis of π-conjugated carbon-rich structures can be employed: (a) either the acetylene group serves as a building block to access acetylene-derived structures or (b) it serves as a synthetic tool to provide other, usually benzenoid, structures. The recently discovered copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction, however, represents a new powerful alternative: it transforms the acetylene group into a five-membered heteroaromatic 1H-1,2,3-triazole (triazole) ring and this gives rise to new opportunities. Compared with all-carbon aromatic non-functional rings, the triazole ring possesses three nitrogen atoms and, thus, can serve as a ligand to coordinate metals, or as a hydrogen bond acceptor and donor. This Feature Article summarises examples of using the triazole ring to construct conjugation- and/or function-related heteroaromatic materials, such as tuneable multichromophoric covalent ensembles, macrocyclic receptors or responsive foldamers. These recent examples, which open a new sub-field within organic materials, started to appear only few years ago and represent "a few more bricks" on the road to carbon-rich functional materials. PMID:21556388

  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. PMID:27115033

  9. On the use of a hierarchical multi-level building block basis function scheme in periodic plasmonic structures

    NASA Astrophysics Data System (ADS)

    Zheng, X.; Valev, V. K.; Volskiy, V.; Vandenbosch, Guy A. E.; Moshchalkov, V. V.

    2014-05-01

    A Volumetric Method of Moments algorithm is applied to predict the plasmonic responses of chiral metamaterials. This algorithm is based on the use of a multi-level building block basis function scheme, in combination with a dedicated Kummer transformation in the calculation of periodic Green's functions. The validity of the algorithm is demonstrated by analyzing a Ninja Star periodic structure. A good agreement can be found between simulation and experiment.

  10. Selectively fluorinated cyclohexane building blocks: Derivatives of carbonylated all-cis-3-phenyl-1,2,4,5-tetrafluorocyclohexane

    PubMed Central

    Ayoup, Mohammed Salah; Cordes, David B; Slawin, Alexandra M Z

    2015-01-01

    Summary Palladium catalysed carbonylation reactions using the meta- and para-iodo derivatives of all-cis-3-phenyl-1,2,4,5-tetrafluorocyclohexane (4) are illustrated as the start point for a variety of functional group interconversions. The resultant benzaldehyde and benzoic acids offer novel building blocks for further derivatisation and facilitate the incorporation of the facially polarised all-cis-1,2,4,5-tetrafluorocyclohexane motif into more advanced molecular scaffolds. PMID:26877788

  11. 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.

  12. 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. PMID:15995855

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

    PubMed Central

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

    2015-01-01

    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. PMID:26066737

  14. 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

    2015-01-01

    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. PMID:26066737

  15. Using Blocks to Build Art Concepts: A New Look at an Old Friend.

    ERIC Educational Resources Information Center

    Gelfer, Jeffrey I.; Perkins, Peggy G.

    From the 1950s through the 1970s, children's play with blocks was seen as facilitating many developmental and educational outcomes, including art and creativity. In the 1980s there is less interest in the use of blocks to help children acquire art concepts and sensitivities as the pressure for back to the basics increases. This paper aims to…

  16. Optimized interferometric setup for chiral and achiral ultrafast IR spectroscopy.

    PubMed

    Dutta, Biplab; Helbing, Jan

    2015-06-15

    We report an actively stabilized interferometer-based set-up for the detection of vibrational circular dichroism (VCD) and optical rotatory dispersion (VORD) with femtosecond laser pulses. Our approach combines and improves elements of several previous measurement strategies, including signal amplification in a crossed polarizer configuration, precise control and modulation of polarization, phase stability, tight focusing, broad-band detection and spectral interferometry. Their importance for static and transient measurements is motivated by a signal analysis based on Jones matrices and response theory. Only depending on the pump-beam polarization, the set-up can selectively detect transient VCD and VORD or transient linear birefringence (LB) and linear dichroism (LD), which usually constitute the dominant artifacts in the chiral measurements. For illustration we present transient LB and LD data of an achiral Rhenium carbonyl complex, detected simultaneously by spectral interferometry, and we analyze residual background signals in the experimental configuration for transient chiral spectroscopy. PMID:26193616

  17. Achiral flexible liquid crystal trimers exhibiting chiral conglomerates.

    PubMed

    Sasaki, Haruna; Takanishi, Yoichi; Yamamoto, Jun; Yoshizawa, Atsushi

    2016-04-14

    Chiral conglomerates of domains with opposite handedness have attracted much attention from researchers. We prepared a homologous series of achiral liquid crystal trimers in which two phenylpyrimidine units and one biphenyl unit were connected via flexible methylene spacers. We investigated their phase transition behaviour. Some trimers possessing odd-numbered spacers were found to exhibit a nematic phase and a dark chiral conglomerate phase possessing a layered structure. The chiral characteristics were confirmed by uncrossing the polarizers in opposite directions. The layer spacing detected using X-ray diffraction was about 80% of the molecular length. The structure-property relations indicate that intermolecular interactions cause a conformational change in the trimers possessing flexible odd-numbered methylene spacers to form helical conformers with axial chirality, which might induce chiral segregation and layer deformation to drive the chiral conglomerates. PMID:26947890

  18. Microscopic origin of chiral shape induction in achiral crystals

    NASA Astrophysics Data System (ADS)

    Xiao, Wende; Ernst, Karl-Heinz; Palotas, Krisztian; Zhang, Yuyang; Bruyer, Emilie; Peng, Lingqing; Greber, Thomas; Hofer, Werner A.; Scott, Lawrence T.; Fasel, Roman

    2016-04-01

    In biomineralization, inorganic materials are formed with remarkable control of the shape and morphology. Chirality, as present in the biomolecular world, is therefore also common for biominerals. Biomacromolecules, like proteins and polysaccharides, are in direct contact with the mineral phase and act as modifiers during nucleation and crystal growth. Owing to their homochirality—they exist only as one of two possible mirror-symmetric isomers—their handedness is often transferred into the macroscopic shape of the biomineral crystals, but the way in which handedness is transmitted into achiral materials is not yet understood at the atomic level. By using the submolecular resolution capability of scanning tunnelling microscopy, supported by photoelectron diffraction and density functional theory, we show how the chiral ‘buckybowl’ hemibuckminsterfullerene arranges copper surface atoms in its vicinity into a chiral morphology. We anticipate that such new insight will find its way into materials synthesis techniques.

  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. Carboranedithiols: building blocks for self-assembled monolayers on copper surfaces.

    PubMed

    Baše, Tomáš; Bastl, Zdeněk; Havránek, Vladimír; Macháček, Jan; Langecker, Jens; Malina, Václav

    2012-08-28

    Two different positional isomers of 1,2-dicarba-closo-dodecaboranedithiols, 1,2-(HS)(2)-1,2-C(2)B(10)H(10) (1) and 9,12-(HS)(2)-1,2-C(2)B(10)H(10) (2), have been investigated as cluster building blocks for self-assembled monolayers (SAMs) on copper surfaces. These two isomers represent a convenient system in which the attachment of SH groups at different positions on the skeleton affects their acidic character and thus also determines their reactivity with a copper surface. Isomer 1 exhibited etching of polycrystalline Cu films, and a detailed investigation of the experimental conditions showed that both the acidic character of SH groups and the presence of oxygen at the copper surface play crucial roles in how the surface reaction proceeds: whether toward a self-assembled monolayer or toward copper film etching. We found that each positional isomer requires completely different conditions for the preparation of a SAM on copper surfaces. Optimized conditions for the former isomer required the exposure of a freshly prepared Cu surface to vapor of 1 in vacuum, which avoided the presence of oxygen and moisture. Adsorption from a dichloromethane solution afforded a sparsely covered Cu(0) surface; isomer 1 effectively removes the surface copper(I) oxide, forming a soluble product, but apparently binds only weakly to the clean Cu(0) surface. In contrast, adsorption of the latter, less volatile isomer proceeded better from a dichloromethane solution than from the vapor phase. Isomer 2 was even able to densely cover the copper surface cleaned up by the dichloromethane solution of 1. Both isomers exhibited high capacity to remove oxygen atoms from the surface copper(I) oxide that forms immediately after the exposure of freshly prepared copper films to ambient atmosphere. Isomer 2 showed suppression of Cu film oxidation. A number of methods including X-ray photoelectron spectroscopy (XPS), X-ray Rutherford back scattering (RBS), proton-induced X-ray emission (PIXE) analysis

  1. 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

  2. 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

  3. Surprising Image Revises Understanding Of Dwarf Galaxies -- Building Blocks of the Universe

    NASA Astrophysics Data System (ADS)

    2003-01-01

    Hertz. However, cold molecular Hydrogen cannot be observed with current telescopes. Instead, astronomers look for CO, which emits at several radio frequencies, and then estimate the amount of molecular Hydrogen based on how much CO they see. Based on the new observations of CO, the astronomers concluded that IC 10 has much less molecular gas than previously thought and apparently has a much smaller percentage of molecular gas than our Milky Way. The astronomers add that dwarf galaxies in general are found to have less of the heavy elements than larger, spiral galaxies. They are thus probably more similar to galaxies in the early Universe when there had been less time for stars to produce the heavy elements and then return them to their surroundings through supernova explosions. Studies of a dwarf irregular galaxy like IC 10 therefore give astronomers new insights about how stars formed in the distant past. In addition, many astronomers believe dwarf galaxies are the "building blocks of the Universe," from which larger galaxies were assembled through mergers. "The beauty of this is that dwarf irregulars are the most numerous type of galaxy, and many, like IC 10, are relatively nearby. That means we can learn about star formation in such extreme environments by studying nearby dwarf galaxies. That's fortunate, because we cannot observe extremely distant galaxies with sufficient detail," Walter said. Studies of molecules in galaxies also will benefit from the completion of the Atacama Large Millimeter Array (ALMA), an international millimeter-wave telescope project to be located in the high plains of northern Chile. With ALMA, astronomers will be able to study galaxies with greater detail and sensitivity to learn more about the nature of the building blocks of the Universe. Research with the Owens Valley Radio Telescope, operated by the California Institute of Technology, is supported by NSF grant AST96-13717. The National Radio Astronomy Observatory is a facility of the National

  4. Comprehensive procedural approach for transferring or comparative analysis of analogue IP building blocks towards different CMOS technologies

    NASA Astrophysics Data System (ADS)

    Gevaert, Dorine M.

    2009-05-01

    The challenges for the next generation of integrated circuit design of analogue and mixed-signal building blocks in standard CMOS technologies for signal conversion demand research progress in the emerging scientific fields of device physics and modelling, converter architectures, design automation, quality assurance and cost factor analysis. Estimation of mismatch for analogue building blocks at the conceptual level and the impact on active area is not a straightforward calculation. The proposed design concepts reduce the over-sizing of transistors, compared with the existing methods, with 15 to 20% for the same quality specification. Besides the reduction of the silicon cost also the design time cost for new topologies is reduced considerably. Comparison has been done for current mode converters (ADC and DAC) and focussing on downscaling technologies. The developed method offers an integrated approach on the estimation of architecture performances, yield and IP-reuse. Matching energy remains constant over process generations and will be the limiting factor for current signal processing. The comprehensive understanding of all sources of mismatches and the use of physical based mismatch modelling in the prediction of mismatch errors, more adequate and realistic sizing of all transistors will result in an overall area reduction of analogue IP blocks. For each technology the following design curves are automatically developed: noise curves for a specified signal bandwidth, choice of overdrive voltage versus lambda and output resistance, physical mismatch error modelling on target current levels. The procedural approach shares knowledge of several design curves and speeds up the design time.

  5. Building blocks in hierarchical clustering scenarios and their connection with damped Lyα systems

    NASA Astrophysics Data System (ADS)

    Cora, Sofía A.; Tissera, Patricia B.; Lambas, Diego G.; Mosconi, Mirta B.

    2003-08-01

    We carried out a comprehensive analysis of the chemical properties of the interstellar medium (ISM) and the stellar population (SP) of current normal galaxies and their progenitors in a hierarchical clustering scenario. We compared the results with observations of damped Lyman-α systems (DLAs) under the hypothesis that, at least, part of the observed DLAs could originate in the building blocks of present-day normal galaxies. We used a hydrodynamical cosmological code which includes star formation and chemical enrichment. Galaxy-like objects are identified at z= 0 and then followed back in time. Random lines of sight (LOS) are drawn through these structures in order to mimic damped Lyman-α systems. We then analysed the chemical properties of the ISM and SP along the LOS. We found that the progenitors of current galaxies in the field with mean L < 0.5L* and virial circular velocity of 100-250 km s-1 could be the associated DLA galaxies. For these systems we detected a trend for to increase with redshift. We found moderate metallicity evolution for [Zn/H], [Fe/H] and [Si/H]. However, when we applied the observational filter suggested by Boissé et al. (1998) in order to restrict the sample to the observed limits in densities and metallicities, we found mild evolution consistent with observational results that include dust corrections. [Si/Fe] and [S/Fe] show weak α-enhancement in agreement with observations corrected by dust depletion. We found α/Fe in the ISM and SP to have more homogeneous abundances than [Fe/H] and [Zn/H]. In our models, the global metallicity evolution is driven by the high metallicity and high column density simulated DLAs, which have low impact parameters (b < 5 kpc), and SPs with more than 108 Msolar. Our results suggest that geometrical effects could be the mechanism responsible for the non-detectability of high-metallicity and high-column-density DLAs. We found sub-DLAs to map preferentially the outskirts of the simulated DLA

  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. Polymer encapsulated 2.5D sensor arrays as building blocks for creating smart objects

    NASA Astrophysics Data System (ADS)

    Lishchynska, Maryna; Moore, Liam; Rogoz, Daniel; Delaney, Kieran; Barrett, John

    2010-03-01

    One of the key challenges in developing effective and scalable technologies necessary to realise future pervasive systems and ubiquitous computing is implementing a methodology that genuinely integrates embedded sensing and processing capabilities with everyday materials and objects. Embedding intelligent systems into polymer materials and using such "smart blocks" for constructing smart objects is a promising way to achieve the above. This work provides new solutions to challenges of realising a functional system, comprising sensing, processing and actuating components, fully encapsulated in a block of polymer material. The paper also investigates the possibilities of connecting arrays of such smart blocks in 1.5-D and 2.5-D arrangements to form a modular smart object. Experimental and numerical studies were conducted to establish a level of degradation in mechanical properties and strength of the plastic materials embedded with inserts. In current work, a bare cubic system and the system in a capsule-like package were realised and tested. The results of a full physical characterisation of both individual smart blocks and smart block arrays are presented.

  8. 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.

  9. First principles calculations of nucleon and pion form factors: understanding the building blocks of nuclear matter from lattice QCD

    SciTech Connect

    Constantia Alexandrou; Bojan Bistrovic; Robert Edwards; P de Forcrand; George Fleming; Philipp Haegler; John Negele; Konstantinos Orginos; Andrew Pochinsky; Dru Renner; David Richards; Wolfram Schroers; Antonios Tsapalis

    2005-10-01

    Lattice QCD is an essential complement to the current and anticipated DOE-supported experimental program in hadronic physics. In this poster we address several key questions central to our understanding of the building blocks of nuclear matter, nucleons and pions. Firstly, we describe progress at computing the electromagnetic form factors of the nucleon, describing the distribution of charge and current, before considering the role played by the strange quarks. We then describe the study of transition form factors to the Delta resonance. Finally, we present recent work to determine the pion form factor, complementary to the current JLab experimental determination and providing insight into the approach to asymptotic freedom.

  10. Enhancing Energetic Properties and Sensitivity by Incorporating Amino and Nitramino Groups into a 1,2,4-Oxadiazole Building Block.

    PubMed

    Tang, Yongxing; Gao, Haixiang; Mitchell, Lauren A; Parrish, Damon A; Shreeve, Jean'ne M

    2016-01-18

    A single nitrogen-rich heterocyclic ring with many energetic groups is expected to exhibit excellent detonation performance. We report an effective approach for the synthesis of 3-amino-5-nitramino-1,2,4-oxadiazole, which has nitramino and amino groups in the same building block. The single-crystal X-ray structure shows layered hydrogen-bonding pairs as well as the presence of a water molecule which ensure insensitivity. Through incorporation of a cation, the hydrazinium or hydroxylammonium salts exhibit good energetic performance and acceptable sensitivities. PMID:26617389

  11. 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…

  12. 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…

  13. Heparin-induced circular dichroism of an achiral, bicyclic species.

    PubMed

    Stanley, Floyd E; Warner, Andrew M; McWilliams, Kayla M; Stalcup, Apryll M

    2011-01-01

    Antimalarial drugs have shown potential in suppressing the role of glycosaminoglycans (GAGs) in the pathology of prion protein conformational disorders (e.g. "Mad Cow" disease) by competing for sites of electrostatic interaction. In this study, circular dichroism (CD) and UV/Visible (UV/Vis) absorption spectroscopy techniques were used to investigate the interactions between N-methyl-N'-(7-chloro-4-quinolyl)-1,3-diaminopropane (QD), an achiral, bicyclic compound similar to previously investigated antimalarial drugs, and heparin, a complex GAG that is frequently used as a clinical anticoagulant. Relatively intense heparin-induced CD features were observed for QD and were noted to be radically different from previous studies using related chiral drugs, underscoring the importance of the Pfieffer effect on this and similar heparin research. Additionally, the induced CD for QD was observed to be highly dependent upon drug concentration, heparin concentration, system pH, equilibration time, and ionic strength. These results, in connection with recent work, provide new insight into the nature of the association between GAGs and antimalarial species. PMID:21125690

  14. Chiral structures from achiral liquid crystals in cylindrical capillaries

    PubMed Central

    Jeong, Joonwoo; Kang, Louis; Davidson, Zoey S.; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2015-01-01

    We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects. PMID:25825733

  15. Chiral structures from achiral liquid crystals in cylindrical capillaries.

    PubMed

    Jeong, Joonwoo; Kang, Louis; Davidson, Zoey S; Collings, Peter J; Lubensky, Tom C; Yodh, A G

    2015-04-14

    We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects. PMID:25825733

  16. Chiral structures from achiral liquid crystals in cylindrical capillaries

    NASA Astrophysics Data System (ADS)

    Jeong, Joonwoo; Kang, Louis; Davidson, Zoey S.; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2015-04-01

    We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects.

  17. Deconstructing building blocks: preschoolers' spatial assembly performance relates to early mathematical skills.

    PubMed

    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 was evaluated. Spatial skill independently predicted a significant amount of the variability in concurrent mathematical performance. Finally, the relation between spatial assembly skill and socioeconomic status (SES), 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. 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

  19. Expedient Route To Access Rare Deoxy Amino l-Sugar Building Blocks for the Assembly of Bacterial Glycoconjugates.

    PubMed

    Sanapala, Someswara Rao; Kulkarni, Suvarn S

    2016-04-13

    Bacterial glycoproteins and oligosaccharides contain several rare deoxy amino l-sugars which are virtually absent in the human cells. This structural difference between the bacterial and host cell surface glycans can be exploited for the development of carbohydrate based vaccines and target specific drugs. However, the unusual deoxy amino l-sugars present in the bacterial glycoconjugates are not available from natural sources. Thus, procurement of orthogonally protected rare l-sugar building blocks through efficient chemical synthesis is a crucial step toward the synthesis of structurally well-defined and homogeneous complex glycans. Herein, we report a general and expedient methodology to access a variety of unusual deoxy amino l-sugars starting from readily available l-rhamnose and l-fucose via highly regioselective, one-pot double serial and double parallel displacements of the corresponding 2,4-bistriflates using azide and nitrite anions as nucleophiles. Alternatively, regioselective monotriflation at O2, O3, and O4 of l-rhamnose/l-fucose allowed selective inversions at respective positions leading to diverse rare sugars. The orthogonally protected deoxy amino l-sugar building blocks could be stereoselectively assembled to obtain biologically relevant bacterial O-glycans, as exemplified by the first total synthesis of the amino linker-attached, conjugation-ready tetrasaccharide of O-PS of Yersinia enterocolitica O:50 strain 3229 and the trisaccharide of Pseudomonas chlororaphis subsp. aureofaciens strain M71. PMID:27002789

  20. 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. PMID:26002961

  1. Biophysical properties of dermal building-blocks affects extra cellular matrix assembly in 3D endogenous macrotissue.

    PubMed

    Urciuolo, F; Garziano, A; Imparato, G; Panzetta, V; Fusco, S; Casale, C; Netti, P A

    2016-03-01

    The fabrication of functional tissue units is one of the major challenges in tissue engineering due to their in vitro use in tissue-on-chip systems, as well as in modular tissue engineering for the construction of macrotissue analogs. In this work, we aim to engineer dermal tissue micromodules obtained by culturing human dermal fibroblasts into porous gelatine microscaffold. We proved that such stromal cells coupled with gelatine microscaffolds are able to synthesize and to assemble an endogenous extracellular matrix (ECM) resulting in tissue micromodules, which evolve their biophysical features over the time. In particular, we found a time-dependent variation of oxygen consumption kinetic parameters, of newly formed ECM stiffness and of micromodules self-aggregation properties. As consequence when used as building blocks to fabricate larger tissues, the initial tissue micromodules state strongly affects the ECM organization and maturation in the final macrotissue. Such results highlight the role of the micromodules properties in controlling the formation of three-dimensional macrotissue in vitro, defining an innovative design criterion for selecting tissue-building blocks for modular tissue engineering. PMID:26824879

  2. 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

  3. EDITORIAL: Nature's building blocks Nature's building blocks

    NASA Astrophysics Data System (ADS)

    Engel, Andreas

    2009-10-01

    The scanning tunnelling microscope (STM), invented by Gerd Binnig and Heinrich Rohrer in the early 1980s in the IBM Laboratory in Zurich, and the atomic force microscope (AFM) that followed shortly afterwards, were key developments that initiated a new era in scientific research: nanotechnology. These and related scanning probe microscopes have become fruitful tools in the study of cells, supramolecular assemblies and single biomolecules, as well as other nanoscale structures. In particular, the ability to investigate living matter in native environments made possible by atomic force microscopy, has allowed pronounced progress in biological research. The journal Nanotechnology was the first to serve as a publication platform for this rapidly developing field of science. The journal celebrates its 20th volume with this special issue, which presents a collection of original research articles in various fields of science, but all with the common feature that the structures, processes and functions all take place at the nanometre scale. Scanning probe microscopes are constantly being devised with increasingly sophisticated sensing and actuating features that optimize their performance. However, while these tools continue to provide impressive and informative images of nanoscale systems and allow single molecules to be manipulated with increasing dexterity, a wider field of research activity stimulated either by or for biology has emerged. The unique properties of matter at the nanoscale, such as localized surface plasmons supported by nanostructures, have been exploited in sensors with unprecedented sensitivity. Nanostructures have also found a profitable role in the encapsulation of molecules for 'smart' drug delivery. The potential application of DNA in the self-assembly of nanostructures guided by molecular recognition is another rapidly advancing area of research. In this issue a group of researchers in Germany report how the addition of copper ions can promote the stability of modified double-stranded DNA. They use scanning force microscope observations to provide insights into the energy landscape as DNA complexes form. This research provides just one example of how developments on biological systems are being applied to research across the spectrum of disciplines. This 20th volume special issue provides a snapshot of current state-of-the-art research activity in various areas of nanotechnology, and highlights the breadth and range of research progressing in this field. The developments reported here highlight the continued prominence of biology-related research and promise a bright future for nanotechnology.

  4. 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…

  5. 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…

  6. 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…

  7. Search for Improved Host Architectures: Application of de Novo Structure-Based Design and High-Throughput Screening Methods to Identify Optimal Building Blocks for Multidentate Ethers.

    SciTech Connect

    Hay, Benjamin P.; Oliferenko, Alex A.; Uddin, Jamal; Zhang, Cungen; Firman, Timothy K.

    2005-12-07

    This paper presents a computational approach to the deliberate design of improved host architectures. The approach, which involves the use of computer-aided design software, is illustrated by application to cation hosts containing multiple aliphatic ether oxygen binding sites. De novo molecule building software, HostDesigner, is interfaced with molecular mechanics software, GMMX, providing a tool for generating and screening millions of potential bidentate building block structures. Enhanced cation binding affinity can be achieved when highly organized building blocks are used to construct macrocyclic hosts.

  8. 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.

  9. 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. PMID:27236420

  10. Building blocks for developing spatial skills: evidence from a large, representative U.S. sample.

    PubMed

    Jirout, Jamie J; Newcombe, Nora S

    2015-03-01

    There is evidence suggesting that children's play with spatial toys (e.g., puzzles and blocks) correlates with spatial development. Females play less with spatial toys than do males, which arguably accounts for males' spatial advantages; children with high socioeconomic status (SES) also show an advantage, though SES-related differences in spatial play have been less studied than gender-related differences. Using a large, nationally representative sample from the standardization study of the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition, and controlling for other cognitive abilities, we observed a specific relation between parent-reported frequency of spatial play and Block Design scores that was invariant across gender and SES. Reported spatial play was higher for boys than for girls, but controlling for spatial play did not eliminate boys' relative advantage on this subtest. SES groups did not differ in reported frequency of spatial play. Future research should consider quality as well as quantity of play, and should explore underlying mechanisms to evaluate causality. PMID:25626442

  11. 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

  12. 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

  13. Preparation of N-tBoc L-glutathione dimethyl and di-tert-butyl esters: versatile synthetic building blocks.

    PubMed

    Falck, J R; Sangras, Bhavani; Capdevila, Jorge H

    2007-01-15

    The title l-glutathione derivatives, containing acid- and base-labile esters, respectively, were obtained in good overall yields. N-(t)Boc l-glutathione dimethyl ester was prepared via Fischer esterification of l-glutathione disulfide (GSSG) using HCl in dry methanol, protection of the amine with (t)Boc(2)O, and tributylphosphine cleavage of the disulfide in wet isopropanol. Alternatively, Fischer esterification and (t)Boc-protection of l-glutathione (GSH) also furnished N-(t)Boc glutathione dimethyl ester accompanied by a small amount of S-(t)Boc that was removed chromatographically. The di-tert-butyl ester was obtained by S-palmitoylation of GSH in TFA as solvent, N-(t)Boc-protection, esterification using (t)BuOH mediated by diisopropylcarbodiimide/copper(I) chloride, and saponification of the thioester. These l-glutathione derivatives are versatile synthetic building blocks for the preparation of S-glutathione adducts. PMID:17070060

  14. Metal-Free Route for the Synthesis of 4-Acyl-1,2,3-Triazoles from Readily Available Building Blocks.

    PubMed

    Thomas, Joice; Goyvaerts, Vince; Liekens, Sandra; Dehaen, Wim

    2016-07-11

    Functionalized 1,2,3-triazole heterocycles have been known for a long time and hold an extraordinary potential in diverse research areas ranging from medicinal chemistry to material science. However, the scope of therapeutically important 1-substituted 4-acyl-1H-1,2,3-triazoles is much less explored, probably due to the lack of synthetic methodologies of good scope and practicality. Here, we describe a practical and efficient one-pot multicomponent reaction for the synthesis of α-ketotriazoles from readily available building blocks such as methyl ketones, N,N-dimethylformamide dimethyl acetal, and organic azides with 100 % regioselectivity. This reaction is enabled by the in situ formation of an enaminone intermediate followed by its 1,3-dipolar cycloaddition reaction with an organic azide. We effectively utilized the developed strategy for the derivatization of various heterocycles and natural products, a protocol which is difficult or impossible to realize by other means. PMID:27172985

  15. Basic sleep and circadian science as building blocks for behavioral interventions: a translational approach for mood disorders.

    PubMed

    Asarnow, Lauren D; Soehner, Adriane M; Harvey, Allison G

    2014-06-01

    Sleep and circadian functioning has been of particular interest to researchers focused on improving treatments for psychiatric illness. The goal of the present paper is to highlight the exciting research that utilizes basic sleep and circadian science as building blocks for intervention in the mood disorders. The reviewed evidence suggests that the sleep and circadian systems are a) disrupted in the mood disorders and linked to symptoms, b) open systems that can be modified, c) the focus of interventions which have been developed to effectively treat sleep disturbance within mood disorders, and d) intimately linked with mood, such that improvements in sleep are associated with improvements in mood. Although significant positive treatment effects are evident, more research is needed to fill the gap in our basic understanding of the relationship between sleep and mood. PMID:24773429

  16. Constraining the coordination geometries of lanthanide centers and magnetic building blocks in frameworks: a new strategy for molecular nanomagnets.

    PubMed

    Liu, Ke; Zhang, Xuejing; Meng, Xixi; Shi, Wei; Cheng, Peng; Powell, Annie K

    2016-05-01

    Single-molecule magnets (SMMs) and single-chain magnets (SCMs), also known as molecular nanomagnets, are molecular species of nanoscale proportions with the potential for high information storage density and spintronics applications. Metal-organic frameworks (MOFs) are three-dimensional ordered assemblies of inorganic nodes and organic linkers, featuring structural diversity and multiple chemical and physical properties. The concept of using these frameworks as scaffolds in the study of molecular nanomagnets provides an opportunity to constrain the local coordination geometries of lanthanide centers and organize the individual magnetic building blocks (MBBs, including both transition-metal and lanthanide MBBs) into topologically well-defined arrays that represent two key factors governing the magnetic properties of molecular nanomagnets. In this tutorial review, we summarize recent progress in this newly emerging field. PMID:27009851

  17. Basic Sleep and Circadian Science as Building Blocks for Behavioral Interventions: A Translational Approach for Mood Disorders

    PubMed Central

    Asarnow, Lauren D.; Soehner, Adriane M.; Harvey, Allison G.

    2014-01-01

    Sleep and circadian functioning has been of particular interest to researchers focused on improving treatments for psychiatric illness. The goal of the present paper is to highlight the exciting research that utilizes basic sleep and circadian science as building blocks for intervention in the mood disorders. The reviewed evidence suggests that the sleep and circadian systems are 1) disrupted in the mood disorders and linked to symptoms, 2) open systems that can be modified, 3) the focus of interventions which have been developed to effectively treat sleep disturbance within mood disorders, and 4) intimately linked with mood, such that improvements in sleep are associated with improvements in mood. Although, significant positive treatment effects are evident, more research is needed to fill the gap in our basic understanding of the relationship between sleep and mood. PMID:24773429

  18. 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. PMID:26851528

  19. Synthesis of a versatile building block combining cyclen-derivative DO3A with a polyamine via a rigid spacer.

    PubMed

    Drahoš, Bohuslav; Trávníček, Zdeněk

    2013-01-01

    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. PMID:24225773

  20. 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.

  1. Multi-component superstructures self-assembled from nanocrystal building blocks.

    PubMed

    Tan, Rui; Zhu, Hua; Cao, Can; Chen, Ou

    2016-05-21

    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. PMID:27136751

  2. 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.

  3. 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.

  4. Metal-containing polymers: building blocks for functional (nano)materials.

    PubMed

    Wang, Xiaosong; McHale, Ronan

    2010-02-16

    The incorporation of metallic units into polymer chains has emerged as a promising route towards functional metal-containing (nano)materials. The resulting polymers possess rich functions derived from their metallic elements, such as redox, optical, catalytic and magnetic properties. In addition, the directional and dynamic nature of metal coordination interactions provides further variables for the exploration of novel materials with designed nanostructures. These types of polymers can be synthesized through direct metal-ligand coordination or chain polymerization of metal containing monomers. Depending on the polymerization techniques and starting components, the resulting polymers, akin to their organic counterparts, can be produced in the form of insoluble networks, processible chain structures, gels or colloids. Research into this rising multidisciplinary subject has benefited from recent progress in several related areas such as supramolecular chemistry, colloidal chemistry etc., with the combination of the relative merits of each ensuring further developments in each individual discipline. For example, as a result of studies into organometallic block copolymers self-assembly behavior, living supramolecular polymerization has been unprecedentedly realized for the architectural design of micelles (see image on the right). Nevertheless, the field is still in a developmental stage and offers ample opportunities for fundamental research, as well as material exploration. In this Feature Article, we intend to overview the field with a brief survey of recent literature. PMID:21590911

  5. 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.

  6. 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%.

  7. 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.

  8. 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.

  9. Octahedral niobium chloride clusters as building blocks of templated prussian blue framework analogues.

    PubMed

    Yan, Bangbo; Zhou, Huajun; Lachgar, Abdessadek

    2003-12-29

    The preparation, structure, and magnetic properties of the first three-dimensional framework containing octahedral niobium cyanochloride clusters as building units are reported. Reactions of aqueous solutions of (Me(4)N)(2)K(2)[Nb(6)Cl(12)(CN)(6)] (2) with aqueous solutions of MnCl(2) result in the precipitation of the compound (Me(4)N)(2)[MnNb(6)Cl(12)(CN)(6)] (3). The structure of 3 was determined from single-crystal X-ray diffraction study (crystal data: cubic, Fm3macrom(No. 225), a = 15.513(4) A, V = 3733.2(12) A(3), Z = 4). Its 3D framework is based on edge-bridged [Nb(6)Cl(12)](2+) clusters and Mn(2+) ions bridged by cyanide ligands to form a cfc lattice [MnNb(6)Cl(12)(CN)(6)](2)(-) in which all tetrahedral sites are occupied by the cations (Me(4)N)(+) which act as charge compensating template. The structure of 3 can be considered as an expansion of the Prussian blue framework in which [Fe(CN)(6)](4)(-) is replaced by the cluster [Nb(6)Cl(12)(CN)(6)](4)(-). Magnetic susceptibility measurements indicate that Mn(2+) is present in a high spin d(5) configuration. No magnetic ordering is observed. PMID:14686862

  10. 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.

  11. Templated synthesis of porous particles with tunable pore structures from nanoscale building blocks

    NASA Astrophysics Data System (ADS)

    Wu, Zhiwang

    Porous silica, carbon, titania and carbon/silica composite micro- or nano-materials have been synthesized by the templated self-assembly approaches through an aerosol-assisted process or hydrothermal technique. Porous silica particles with controllable hierarchical pore structure (from hexagonal to lamellar or hierarchical) have been prepared through tuning the hydrophilic and hydrophobic balance among silicate, cetyltrimethylammonium bromide (CTAB), and hydrophobic poly(propylene oxide) (PPO, H[OCH(CH 3)CH2nOH) additives during a dynamic aerosol-assisted process. Aerosol-assisted self-assembly of hollow silica microspheres with microporous shell (HSMMS) are prepared by utilizing the block copolymer F127's aggregating behavior in basic solution and the self-assembly between silicate and amphiphilic tetrapropylammonium hydroxide (TPAOH) molecules. Interactions of TPAOH with both F127 and silicate are necessary for avoiding the phase separation between silicate and F127 aggregates because of the lack of hydrogen bonding interactions. Therefore, F127 aggregates with various sizes act as the core template while TPAOH molecules or TPAOH aggregates formed by excessive TPAOH molecules stay in the silica shell. Removal of F127 and TPAOH by solvent extraction results in the HSMMS materials. Mesoporous carbon/silica composite with both meso- and molecular ordering has been synthesized by carbonization of as-synthesized phenylene/silica/surfactant hybrid by co-assembly of BTEB and Pluronic surfactant P123. Removal of silica from carbon/silica composite results in the mesoporous carbon which retains some of the meso-ordering and has many worm-like pores due to silica dissolution. This mesoporous carbon has potential applications in such field as hydrogen storage, catalysis, and other areas. Hollow carbon microspheres with micropores in the shell and carbon nanotubes on the outer surface have been prepared using resols as the carbon precursor and hydrophobic PPO additives as

  12. 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.

  13. Enantioselective silyl protection of alcohols promoted by a combination of chiral and achiral Lewis basic catalysts

    NASA Astrophysics Data System (ADS)

    Manville, Nathan; Alite, Hekla; Haeffner, Fredrik; Hoveyda, Amir H.; Snapper, Marc L.

    2013-09-01

    Catalytic enantioselective monosilylations of diols and polyols furnish valuable alcohol-containing molecules in high enantiomeric purity. These transformations, however, require high catalyst loadings (20-30 mol%) and long reaction times (2-5 days). Here, we report that a counterintuitive strategy involving the use of an achiral co-catalyst structurally similar to the chiral catalyst provides an effective solution to this problem. A combination of seemingly competitive Lewis basic molecules can function in concert such that one serves as an achiral nucleophilic promoter and the other performs as a chiral Brønsted base. On the addition of 7.5-20 mol% of a commercially available N-heterocycle (5-ethylthiotetrazole), reactions typically proceed within one hour, and deliver the desired products in high yields and enantiomeric ratios. In some instances, there is no reaction in the absence of the achiral base, yet the presence of the achiral co-catalyst gives rise to facile formation of products in high enantiomeric purity.

  14. Enumeration of chiral and achiral edge and face substitutions of buckminsterfullerene

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.

    1995-05-01

    The edge and face groups of the buckminsterfullerene cluster are formulated. The generalized character cycle indices of all the irreducible representations of both edge and face groups are obtained. The generating functions computed from these groups yield the chiral and achiral isomers, and mappings that transform according to the specified irreducible representation for edge and face colorings of buckminsterfullerene.

  15. 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

  16. A comparative analysis of pre-Silurian crustal building blocks of the northern and the southern Appalachian orogen

    USGS Publications Warehouse

    Hibbard, J.P.; van Staal, C.R.; Rankin, D.W.

    2007-01-01

    The New York promontory serves as the divide between the northern and southern segments of the Appalachian orogen. Antiquated subdivisions, distinct for each segment, implied that they had lithotectonic histories that were independent of each other. Using new lithotectonic subdivisions we compare first order features of the pre-Silurian orogenic 'building blocks' in order to test the validity of the implication of independent lithotectonic histories for the two segments. Three lithotectonic divisions, termed here the Laurentian, Iapetan, and the peri-Gondwanan realms, characterize the entire orogen. The Laurentian realm, composed of native North American rocks, is remarkably uniform for the length of the orogen. It records the multistage Neoproterozoic-early Paleozoic rift-drift history of the Appalachian passive margin, formation of a Taconic Seaway, and the ultimate demise of both in the Middle Ordovician. The Iapetan realm encompasses mainly oceanic and magmatic arc tracts that once lay within the Iapetus Ocean, between Laurentia and Gondwana. In the northern segment, the realm is divisible on the basis of stratigraphy and faunal provinciality into peri-Laurentian and peri-Gondwanan tracts that were amalgamated in the Late Ordovician. South of New York, stratigraphic and faunal controls decrease markedly; rock associations are not inconsistent with those of the northern Appalachians, although second-order differences exist. Exposed exotic crustal blocks of the peri-Gondwanan realm include Ganderia, Avalonia, and Meguma in the north, and Carolinia in the south. Carolinia most closely resembles Ganderia, both in early evolution and Late Ordovician-Silurian docking to Laurentia. Our comparison indicates that, to a first order, the pre-Silurian Appalachian orogen developed uniformly, starting with complex rifting and a subsequent drift phase to form the Appalachian margin, followed by the consolidation of Iapetan components and ending with accretion of the peri

  17. 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. PMID:23807714

  18. Making silica nanoparticle-covered graphene oxide nanohybrids as general building blocks for large-area superhydrophilic coatings.

    PubMed

    Kou, Liang; Gao, Chao

    2011-02-01

    We report a facile strategy to synthesize silica nanoparticles-coated graphene oxide (GO-SiO2) nanohybrids in a water-alcohol mixture at room temperature. AFM observations revealed that silica nanoparticles with ca. 50 nm in size were densely and evenly covered on graphene oxide sheets. Due to the space layer of silica nanoparticles, micro-scale GO-SiO2 hybrid plates could be individually dispersed in water and polar organic solvents, promising good solution-based processibility. The growth process of GO-supported silica is traced by TGA and XRD measurements, showing that 24 hours is enough to achieve a fine cover effect for the disappearance of (002) diffraction peak of GO. Based on the high dense overlaying of silica nanoparticles, up to micro-scale silica sheets with thickness of ca. 8 nm were readily fabricated by burning GO-SiO2 at 650 °C in air. Likewise, a centimeter-scale semitransparent film of silica nanosheets was prepared by calcining a GO-SiO2 film. Interestingly, the GO-SiO2 nanohybrids exhibit excellent hydrophilic nature and can be directly applied as a general kind of building blocks to construct large-area superhydrophilic surfaces on arbitrary substrates (e.g., lotus leaf, ceramic tile and polypropylene) through the simple drop-coating method. Such a coating methodology paves the way for making large-area superhydrophilic surface without extra process treatments and damaging the intrinsic structure of substrates. PMID:21109865

  19. NAA-modified DNA oligonucleotides with zwitterionic backbones: stereoselective synthesis of A–T phosphoramidite building blocks

    PubMed Central

    Schmidtgall, Boris; Höbartner, Claudia

    2015-01-01

    Summary Modifications of the nucleic acid backbone are essential for the development of oligonucleotide-derived bioactive agents. The NAA-modification represents a novel artificial internucleotide linkage which enables the site-specific introduction of positive charges into the otherwise polyanionic backbone of DNA oligonucleotides. Following initial studies with the introduction of the NAA-linkage at T–T sites, it is now envisioned to prepare NAA-modified oligonucleotides bearing the modification at X–T motifs (X = A, C, G). We have therefore developed the efficient and stereoselective synthesis of NAA-linked 'dimeric' A–T phosphoramidite building blocks for automated DNA synthesis. Both the (S)- and the (R)-configured NAA-motifs were constructed with high diastereoselectivities to furnish two different phosphoramidite reagents, which were employed for the solid phase-supported automated synthesis of two NAA-modified DNA oligonucleotides. This represents a significant step to further establish the NAA-linkage as a useful addition to the existing 'toolbox' of backbone modifications for the design of bioactive oligonucleotide analogues. PMID:25670992

  20. Energy transfer within self-assembled cyclic multichromophoric arrays based on orthogonally arranged donor-acceptor building blocks.

    PubMed

    Karakostas, Nikolaos; Kaloudi-Chantzea, Antonia; Martinou, Elisabeth; Seintis, Kostas; Pitterl, Florian; Oberacher, Herbert; Fakis, Mihalis; Kallitsis, Joannis K; Pistolis, George

    2015-01-01

    We herein present the coordination-driven supramolecular synthesis and photophysics of a [4+4] and a [2+2] assembly, built up by alternately collocated donor-acceptor chromophoric building blocks based, respectively, on the boron dipyrromethane (Bodipy) and perylene bisimide dye (PBI). In these multichromophoric scaffolds, the intensely absorbing/emitting dipoles of the Bodipy subunit are, by construction, cyclically arranged at the corners and aligned perpendicular to the plane formed by the closed polygonal chain comprising the PBI units. Steady-state and fs time-resolved spectroscopy reveal the presence of efficient energy transfer from the vertices (Bodipys) to the edges (PBIs) of the polygons. Fast excitation energy hopping - leading to a rapid excited state equilibrium among the low energy perylene-bisimide chromophores - is revealed by fluorescence anisotropy decays. The dynamics of electronic excitation energy hopping between the PBI subunits was approximated on the basis of a theoretical model within the framework of Förster energy transfer theory. All energy-transfer processes are quantitatively describable with Förster theory. The influence of structural deformations and orientational fluctuations of the dipoles in certain kinetic schemes is discussed. PMID:26396034

  1. 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.

  2. NAA-modified DNA oligonucleotides with zwitterionic backbones: stereoselective synthesis of A-T phosphoramidite building blocks.

    PubMed

    Schmidtgall, Boris; Höbartner, Claudia; Ducho, Christian

    2015-01-01

    Modifications of the nucleic acid backbone are essential for the development of oligonucleotide-derived bioactive agents. The NAA-modification represents a novel artificial internucleotide linkage which enables the site-specific introduction of positive charges into the otherwise polyanionic backbone of DNA oligonucleotides. Following initial studies with the introduction of the NAA-linkage at T-T sites, it is now envisioned to prepare NAA-modified oligonucleotides bearing the modification at X-T motifs (X = A, C, G). We have therefore developed the efficient and stereoselective synthesis of NAA-linked 'dimeric' A-T phosphoramidite building blocks for automated DNA synthesis. Both the (S)- and the (R)-configured NAA-motifs were constructed with high diastereoselectivities to furnish two different phosphoramidite reagents, which were employed for the solid phase-supported automated synthesis of two NAA-modified DNA oligonucleotides. This represents a significant step to further establish the NAA-linkage as a useful addition to the existing 'toolbox' of backbone modifications for the design of bioactive oligonucleotide analogues. PMID:25670992

  3. Periodic Functionalization of Surface-Confined Pores in a Two-Dimensional Porous Network Using a Tailored Molecular Building Block.

    PubMed

    Tahara, Kazukuni; Nakatani, Kenta; Iritani, Kohei; De Feyter, Steven; Tobe, Yoshito

    2016-02-23

    We present here the periodic functionalization of a two-dimensional (2D) porous molecular network using a tailored molecular building block. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, 1-isoDBA, having an isophthalic acid unit connected by an azobenzene linker to a C12 alkyl chain and five C14 chains, was designed and synthesized. After the optimization of monolayer preparation conditions at the 1,2,4-trichlorobezene (TCB)/graphite interface, scanning tunneling microscopy (STM) observation of the self-assembled monolayer of 1-isoDBA revealed the formation of extended domains of a porous honeycomb-type molecular network, which consists of periodically located nanowells each functionalized by a cyclic hexamer of hydrogen-bonded isophthalic acid units and those without functional groups. This result demonstrates that the present strategy based on precise molecular design is a viable route to site-specific functionalization of surface-confined nanowells. The nanowells of different size can be used for guest coadsorption of different guests, coronene COR and hexakis[4-(phenylethynyl)phenylethynyl]benzene HPEPEB, whose size and shape match the respective nanowells. STM observation of a ternary mixture (1-isoDBA/COR/HPEPEB) at the TCB/graphite interface revealed the site-selective immobilization of the two different guest molecules at the respective nanowells, producing a highly ordered three-component 2D structure. PMID:26838957

  4. Theoretical insights into the photo-protective mechanisms of natural biological sunscreens: building blocks of eumelanin and pheomelanin.

    PubMed

    Marchetti, Barbara; Karsili, Tolga N V

    2016-02-01

    Eumelanin (EM) and pheomelanin (PM) are ubiquitous in mammalian skin and hair--protecting against harmful radiation from the sun. Their primary roles are to absorb solar radiation and efficiently dissipate the excess excited state energy in the form of heat without detriment to the polymeric structure. EU and PM exist as polymeric chains consisting of exotic arrangements of functionalised heteroaromatic molecules. Here we have used state-of-the-art electronic structure calculations and on-the-fly surface hopping molecular dynamics simulations to study the intrinsic deactivation paths of various building blocks of EU and PM. Ultrafast excited state decay, via electron-driven proton transfer (in EU and PM) and proton-transfer coupled ring-opening (in PM) reactions, have been identified to proceed along hitherto unknown charge-separated states in EU and PM oligomers. These results shed light on the possible relaxation pathways that dominate the photochemistry of natural skin melanins. Extrapolation of such findings could provide a gateway into engineering more effective molecular constituents in commercial sunscreens--with reduced phototoxicity. PMID:26753793

  5. Threaded molecular wires as building blocks for advanced polymer blends: WPLEDs, ultra-broadband optical amplifiers, multi color lasers

    NASA Astrophysics Data System (ADS)

    Brovelli, Sergio; Mroz, Marta; Sforazzini, Giuseppe; Virgili, Tersilla; Meinardi, Franco; Paleari, Alberto; Anderson, Harry L.; Lanzani, Guglielmo; Cacialli, Franco

    2011-03-01

    The ability to produce semiconducting polymer blends with white emission spectra, large emission cross sections and broad optical gain is critical to their application in white PLEDs, lasers and broadband amplifiers. Cyclodextrin-encapsulation is an effective means of suppressing detrimental intermolecular interactions, and energy transfer (ET) channels in polymer blends, thus enabling fabrication of white-PLEDs. We show that all such properties combine into a high impact photonic application: ultra-broad optical gain and two-color lasing in a binary polyrotaxane blend. We study the ultrafast photophysics of a blend of a conventional and an encapsulated polyfluorene. The morphology is investigated by microRaman imaging, AFM, and fluorescence lifetime microscopy. We ascribe the ultra-broad optical gain (>850 meV), and the simultaneous ASE for both constituents, to the dual effect of reduced polaron formation and suppressed ET. Our results demonstrate that polyrotaxanes could realistically represent the building blocks for advanced polymer blends with highly controlled optical properties, for applications in solid state lightning, lasers and photovoltaic technologies.

  6. 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.

  7. Self-organizing p-quinquephenyl building blocks incorporating lateral hydroxyl and methoxyl groups into supramolecular nano-assemblies.

    PubMed

    Lu, Zhaoyang; Zhong, Keli; Liu, Yang; Li, Zhaohua; Chen, Tie; Jin, Long Yi

    2016-05-01

    The self-assembling behavior of coil-rod-coil molecules 1a, 1b, and 2a, 2b was investigated using DSC, POM, SAXS, and AFM in bulk and aqueous solutions. These molecules contain p-quinquephenyl groups as rod segments incorporating lateral hydroxyl or methoxyl groups in the center positions and oligo(ethylene oxide)s as the coil segments. Molecules 1a and 1b, with lateral methoxyl groups in the rod segments, self-assemble into oblique columnar structures in the crystalline phase and transform into nematic phases. On the other hand, molecules 2a and 2b, with hydroxyl groups in the center of their rod segments, self-organize into hexagonal perforated lamellar and oblique columnar nano-structures in the crystalline and liquid crystalline phase, respectively. In aqueous solutions, these molecules aggregate into nano-ribbons and vesicles, depending on their lateral groups and oligo(ethylene oxide) chain lengths. These results imply that the lateral methoxyl or hydroxyl groups, present in the center of the rod segments, significantly influence the formation of various supramolecular nano-structures in the bulk state and in aqueous solution. This is achieved via tuning of the non-covalent interactions of the rod building blocks. PMID:27025276

  8. A polypeptide "building block" for the β-trefoil fold identified by "top-down symmetric deconstruction".

    PubMed

    Lee, Jihun; Blaber, Sachiko I; Dubey, Vikash K; Blaber, Michael

    2011-04-15

    Fibroblast growth factor-1, a member of the 3-fold symmetric β-trefoil fold, was subjected to a series of symmetric constraint mutations in a process termed "top-down symmetric deconstruction." The mutations enforced a cumulative exact 3-fold symmetry upon symmetrically equivalent positions within the protein and were combined with a stability screen. This process culminated in a β-trefoil protein with exact 3-fold primary-structure symmetry that exhibited excellent folding and stability properties. Subsequent fragmentation of the repeating primary-structure motif yielded a 42-residue polypeptide capable of spontaneous assembly as a homotrimer, producing a thermostable β-trefoil architecture. The results show that despite pronounced reduction in sequence complexity, pure symmetry in the design of a foldable, thermostable β-trefoil fold is possible. The top-down symmetric deconstruction approach provides a novel alternative means to successfully identify a useful polypeptide "building block" for subsequent "bottom-up" de novo design of target protein architecture. PMID:21315087

  9. 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.

  10. 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.

  11. 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

  12. Genetic dissection of the polyoxin building block-carbamoylpolyoxamic acid biosynthesis revealing the “pathway redundancy” in metabolic networks

    PubMed Central

    2013-01-01

    Background Polyoxin, a peptidyl nucleoside antibiotic, consists of three building blocks including a nucleoside skeleton, polyoximic acid (POIA), and carbamoylpolyoxamic acid (CPOAA), however, little is known about the “pathway redundancy” of the metabolic networks directing the CPOAA biosynthesis in the cell factories of the polyoxin producer. Results Here we report the genetic characterization of CPOAA biosynthesis with revealing a “pathway redundancy” in metabolic networks. Independent mutation of the four genes (polL-N and polP) directly resulted in the accumulation of polyoxin I, suggesting their positive roles for CPOAA biosynthesis. Moreover, the individual mutant of polN and polP also partially retains polyoxin production, suggesting the existence of the alternative homologs substituting their functional roles. Conclusions It is unveiled that argA and argB in L-arginine biosynthetic pathway contributed to the “pathway redundancy”, more interestingly, argB in S. cacaoi is indispensible for both polyoxin production and L-arginine biosynthesis. These data should provide an example for the research on the “pathway redundancy” in metabolic networks, and lay a solid foundation for targeted enhancement of polyoxin production with synthetic biology strategies. PMID:24314013

  13. 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. PMID:26517887

  14. Parallel, linear-scaling building-block and embedding method based on localized orbitals and orbital-specific basis sets.

    PubMed

    Seijo, Luis; Barandiarán, Zoila

    2004-10-01

    We present a linear scaling method for the energy minimization step of semiempirical and first-principles Hartree-Fock and Kohn-Sham calculations. It is based on the self-consistent calculation of the optimum localized orbitals of any localization method of choice and on the use of orbital-specific basis sets. The full set of localized orbitals of a large molecule is seen as an orbital mosaic where each tessera is made of only a few of them. The orbital tesserae are computed out of a set of embedded cluster pseudoeigenvalue coupled equations which are solved in a building-block self-consistent fashion. In each iteration, the embedded cluster equations are solved independently of each other and, as a result, the method is parallel at a high level of the calculation. In addition to full system calculations, the method enables to perform simpler, much less demanding embedded cluster calculations, where only a fraction of the localized molecular orbitals are variational while the rest is frozen, taking advantage of the transferability of the localized orbitals of a given localization method between similar molecules. Monitoring single point energy calculations of large poly(ethylene oxide) molecules and three dimensional carbon monoxide clusters using an extended Huckel Hamiltonian are presented. PMID:15473725

  15. 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. PMID:26608098

  16. 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…

  17. 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…

  18. Making silica nanoparticle-covered graphene oxide nanohybrids as general building blocks for large-area superhydrophilic coatings

    NASA Astrophysics Data System (ADS)

    Kou, Liang; Gao, Chao

    2011-02-01

    We report a facile strategy to synthesize silica nanoparticles-coated graphene oxide (GO-SiO2) nanohybrids in a water-alcohol mixture at room temperature. AFM observations revealed that silica nanoparticles with ca. 50 nm in size were densely and evenly covered on graphene oxide sheets. Due to the space layer of silica nanoparticles, micro-scale GO-SiO2 hybrid plates could be individually dispersed in water and polar organic solvents, promising good solution-based processibility. The growth process of GO-supported silica is traced by TGA and XRD measurements, showing that 24 hours is enough to achieve a fine cover effect for the disappearance of (002) diffraction peak of GO. Based on the high dense overlaying of silica nanoparticles, up to micro-scale silica sheets with thickness of ca. 8 nm were readily fabricated by burning GO-SiO2 at 650 °C in air. Likewise, a centimeter-scale semitransparent film of silica nanosheets was prepared by calcining a GO-SiO2 film. Interestingly, the GO-SiO2 nanohybrids exhibit excellent hydrophilic nature and can be directly applied as a general kind of building blocks to construct large-area superhydrophilic surfaces on arbitrary substrates (e.g., lotus leaf, ceramic tile and polypropylene) through the simple drop-coating method. Such a coating methodology paves the way for making large-area superhydrophilic surface without extra process treatments and damaging the intrinsic structure of substrates.We report a facile strategy to synthesize silica nanoparticles-coated graphene oxide (GO-SiO2) nanohybrids in a water-alcohol mixture at room temperature. AFM observations revealed that silica nanoparticles with ca. 50 nm in size were densely and evenly covered on graphene oxide sheets. Due to the space layer of silica nanoparticles, micro-scale GO-SiO2 hybrid plates could be individually dispersed in water and polar organic solvents, promising good solution-based processibility. The growth process of GO-supported silica is traced by TGA

  19. First enantioseparation and circular dichroism spectra of Au38 clusters protected by achiral ligands

    PubMed Central

    Dolamic, Igor; Knoppe, Stefan; Dass, Amala; Bürgi, Thomas

    2012-01-01

    Bestowing chirality to metals is central in fields such as heterogeneous catalysis and modern optics. Although the bulk phase of metals is symmetric, their surfaces can become chiral through adsorption of molecules. Interestingly, even achiral molecules can lead to locally chiral, though globally racemic, surfaces. A similar situation can be obtained for metal particles or clusters. Here we report the first separation of the enantiomers of a gold cluster protected by achiral thiolates, Au38(SCH2CH2Ph)24, achieved by chiral high-performance liquid chromatography. The chirality of the nanocluster arises from the chiral arrangement of the thiolates on its surface, forming 'staple motifs'. The enantiomers show mirror-image circular dichroism responses and large anisotropy factors of up to 4×10−3. Comparison with reported circular dichroism spectra of other Au38 clusters reveals that the influence of the ligand on the chiroptical properties is minor. PMID:22531183

  20. Ab initio determination of geometries and vibrational characteristics of building blocks of organic super-conductors: TTF and its derivatives.

    PubMed

    Rani, P; Yadav, R A

    2012-12-01

    Molecular behavior of the building block {[2-(1,3-dithiole-2-ylidene)-1,3-dithiole] ≡ tetrathiafulvalene (TTF)} of organic superconductors have been investigated along with its three derivatives, namely, {[2-(1,3-dioxole-2-ylidene)-1,3-dioxole] ≡ tetraoxafulvalene (TOF)}; [2,2]-bi -[[1,3] oxathiolylidene] ≡ Der I and 2-(3H-Furan-2-ylidene)-[1,3] oxathiole ≡ Der II. The properties of the molecules such as molecular geometries, frontier MOs and vibrational spectra have been investigated by using DFT method at the B3LYP level employing 6-311++G(d,p) basis set. The geometrical parameters and atomic charges on various atomic sites of the TTF, TOF, Ders I and II suggest extended conjugation in these systems. The present calculations lead to the reassignments for of some of the fundamentals and new interpretations for some of the observed IR and Raman frequencies. One of the two modes involved in the Fermi resonance giving rise to the doublet 1555 and 1564 cm(-1) needed to be revised and another doublet 3083 and 3108 cm(-1) could be interpreted as a Fermi resonance doublet. Out of the two ν(C = C) modes under the a(1) species, the lower frequency mode is assigned to the ν(C = C) of the ring and the higher one to the ν(C = C) of the central C = C bond contrary to the assignment reported in literature. The conducting properties of these molecules depend mainly on this mode. PMID:23040970

  1. Understanding the ionic liquid [NC4111][NTf2] from individual building blocks: an IR-spectroscopic study.

    PubMed

    Hanke, Kenny; Kaufmann, Matin; Schwaab, Gerhard; Havenith, Martina; Wolke, Conrad T; Gorlova, Olga; Johnson, Mark A; Kar, Bishnu Prasad; Sander, Wolfram; Sanchez-Garcia, Elsa

    2015-04-01

    This study explores the interactions underlying the IR spectra of the ionic liquid [NC4111][NTf2] and its deuterated isotopomer [d9-NC4111][NTf2] by first isolating the spectra of charged ionic building blocks using mass-selective CIVP spectroscopy and then following the evolution of these bands upon sequential assembly of the ionic constituents. The spectra of the (1,1) and (2,2) neutral ion pairs are recorded using superfluid helium droplets as well as a solid neon matrix, while those of the larger charged aggregates are again obtained with CIVP. In general, the cluster spectra are similar to that of the bulk, with the (2,2) system displaying the closest resemblance. Analysis of the polarization-dependent band intensities of the neutral ion pairs in liquid droplets as a function of external electric field yields dipole moments of the neutral aggregates. This information allows a coarse assessment of the packing structure of the neutral pairs to be antiparallel at 0.37 K, in contrast to the parallel arrangement found for the assembly of small, high-dipole neutral molecules with large rotational constants (e.g., HCN). The role of an extra anion or cation attached to both the (1,1) and the (2,2) ion pairs to form the charged clusters is discussed in the context of an additional remote, more unfavorable binding site intrinsic to the nature of the charged IL clusters and as such not anticipated in the bulk phase. Whereas for the anion itself only the lowest energy trans conformer was observed, the higher clusters showed an additional population of the cis conformer. The interactions are found to be consistent with a minimal role of hydrogen bonding. PMID:25749545

  2. 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 . PMID:25881563

  3. 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

  4. Social cognition: empirical contribution. The developmental building blocks of psychopathic traits: revisiting the role of theory of mind.

    PubMed

    Sharp, Carla; Vanwoerden, Salome

    2014-02-01

    In the context of personality disorder development, theories of typical and atypical development both emphasize social cognition as an important building block for personality development. Prior claims of intact theory of mind (ToM) abilities in psychopathic individuals have relied upon a narrow conception of ToM as equivalent to "cognitive empathy." In this article, the authors make use of a broader conception of ToM comprising top-down and bottom-up processing, as well as the fractionation of ToM in terms of reduced or excessive ToM function, to examine relationships between ToM and psychopathic traits. A total of 342 adolescents (ages 12-17; Mage 15.39; SD = 1.45; 61.5% females) completed the Movie Assessment for Social Cognition (Dziobek, Fleck, Kalbe, et al., 2006) and the Child Eyes Test (Baron-Cohen, Wheelwright, Hill, Raste, & Plumb, 2001) in addition to three measures of psychopathic traits. Results demonstrated unique relations between the affective components of psychopathy (callous-unemotional traits [CU traits]) and impairment in both top-down and bottom-up ToM. In addition, excessive ToM related to affective components of psychopathy, while reduced or no ToM related to behavioral components of psychopathy. In mediational analyses, bottom-up ToM was shown to be necessary for top-town ToM in its relation with CU traits. Taken together, these results from the study lend support to revisiting the link between ToM and psychopathy. PMID:24344889

  5. Evolutionary Origin and Conserved Structural Building Blocks of Riboswitches and Ribosomal RNAs: Riboswitches as Probable Target Sites for Aminoglycosides Interaction

    PubMed Central

    Mehdizadeh Aghdam, Elnaz; Barzegar, Abolfazl; Hejazi, Mohammad Saeid

    2014-01-01

    Purpose: Riboswitches, as noncoding RNA sequences, control gene expression through direct ligand binding. Sporadic reports on the structural relation of riboswitches with ribosomal RNAs (rRNA), raises an interest in possible similarity between riboswitches and rRNAs evolutionary origins. Since aminoglycoside antibiotics affect microbial cells through binding to functional sites of the bacterial rRNA, finding any conformational and functional relation between riboswitches/rRNAs is utmost important in both of medicinal and basic research. Methods: Analysis of the riboswitches structures were carried out using bioinformatics and computational tools. The possible functional similarity of riboswitches with rRNAs was evaluated based on the affinity of paromomycin antibiotic (targeting “A site” of 16S rRNA) to riboswitches via docking method. Results: There was high structural similarity between riboswitches and rRNAs, but not any particular sequence based similarity between them was found. The building blocks including "hairpin loop containing UUU", "peptidyl transferase center conserved hairpin A loop"," helix 45" and "S2 (G8) hairpin" as high identical rRNA motifs were detected in all kinds of riboswitches. Surprisingly, binding energies of paromomycin with different riboswitches are considerably better than the binding energy of paromomycin with “16S rRNA A site”. Therefore the high affinity of paromomycin to bind riboswitches in comparison with rRNA “A site” suggests a new insight about riboswitches as possible targets for aminoglycoside antibiotics. Conclusion: These findings are considered as a possible supporting evidence for evolutionary origin of riboswitches/rRNAs and also their role in the exertion of antibiotics effects to design new drugs based on the concomitant effects via rRNA/riboswitches. PMID:24754005

  6. Tetris Is a Foldback Transposon that Provided the Building Blocks for an Emerging Satellite DNA of Drosophila virilis

    PubMed Central

    Dias, Guilherme B.; Svartman, Marta; Delprat, Alejandra; Ruiz, Alfredo; Kuhn, Gustavo C.S.

    2014-01-01

    Transposable elements (TEs) and satellite DNAs (satDNAs) are abundant components of most eukaryotic genomes studied so far and their impact on evolution has been the focus of several studies. A number of studies linked TEs with satDNAs, but the nature of their evolutionary relationships remains unclear. During in silico analyses of the Drosophila virilis assembled genome, we found a novel DNA transposon we named Tetris based on its modular structure and diversity of rearranged forms. We aimed to characterize Tetris and investigate its role in generating satDNAs. Data mining and sequence analysis showed that Tetris is apparently nonautonomous, with a structure similar to foldback elements, and present in D. virilis and D. americana. Herein, we show that Tetris shares the final portions of its terminal inverted repeats (TIRs) with DAIBAM, a previously described miniature inverted transposable element implicated in the generation of chromosome inversions. Both elements are likely to be mobilized by the same autonomous TE. Tetris TIRs contain approximately 220-bp internal tandem repeats that we have named TIR-220. We also found TIR-220 repeats making up longer (kb-size) satDNA-like arrays. Using bioinformatic, phylogenetic and cytogenomic tools, we demonstrated that Tetris has contributed to shaping the genomes of D. virilis and D. americana, providing internal tandem repeats that served as building blocks for the amplification of satDNA arrays. The β-heterochromatic genomic environment seemed to have favored such amplification. Our results imply for the first time a role for foldback elements in generating satDNAs. PMID:24858539

  7. Three-dimensional roselike α-Ni(OH)₂ assembled from nanosheet building blocks for non-enzymatic glucose detection.

    PubMed

    Lu, Pan; Lei, Yuting; Lu, Shengjun; Wang, Qing; Liu, Qibin

    2015-06-23

    Glucose detection plays very important roles in diagnostics and management of diabetes. The search for novel catalytic materials with appropriate architectures is the key step in the fabrication of highly sensitive glucose sensors. In this work, α-Ni(OH)2 roselike structures (Ni(OH)2-RS) assembled from nanosheet building blocks were successfully synthesized by a hydrothermal method through the hydrolysis of nickel chloride in the mixed solvents of water and ethanol with the assistance of polyethylene glycol (PEG). The structure and morphology of the roselike α-Ni(OH)2 were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and N2 adsorption-desorption isotherm measurement. TEM and FE-SEM images showed that the synthesized Ni(OH)2 was roselike and the size of the leaf-shaped nanosheet was about 5 nm in thickness, which leads to larger active surface areas and faster electron transfer for the detection of glucose. Compared with the bare GCE and bulk Ni(OH)2/GCE, the Ni(OH)2-RS/GCE had higher catalytic activity toward the oxidation of glucose. Under the optimal conditions, the Ni(OH)2-RS/GCE offers a variety of merits, such as a wide linear response window for glucose concentrations ranging from 0.87 μM to 10.53 mM, short response time (3s), a lower detection limit of 0.08 μM (S/N=3), as well as long term stability and repeatability. PMID:26092336

  8. 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.

  9. Regular chemisorption of hydrogen on achiral single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bogdanova, D. A.; Bulyarskii, S. V.

    2016-07-01

    Regular chemisorption of hydrogen on achiral single-walled carbon nanotubes has been investigated with the use of AM1 quantum-chemical semiempirical method. It has been found that regular hydrogen chemisorption deforms nanotubes, in some cases leading to stable prismatic modifications. The dependence of the adsorption energy on the density of hydrogen coverage has been found. A procedure for determining the adsorption energy by the spectra of thermally stimulated desorption has been proposed.

  10. A homochiral Cu(i) coordination polymer based on achiral precursors and its photocatalytic properties.

    PubMed

    He, Xiang; Fang, Kang; Guo, Xiao-Hai; Han, Jing; Lu, Xiao-Peng; Li, Ming-Xing

    2015-08-14

    A homochiral three-dimensional framework material, [Cu(7)(4-bpt)(6)(CN)(H(2)O)] (1) (4-bpt = 3,5-bis(4-pyridyl)-1,2,4-triazole), has been successfully synthesized by solvothermal reaction, which is generated through an unusual spontaneous asymmetrical crystallization from achiral precursors, and its photocatalytic properties in degradation of organic dyes are also investigated. PMID:26134666

  11. 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

  12. Active Esters as Pseudostoppers for Slippage Synthesis of [2]Pseudorotaxane Building Blocks: A Straightforward Route to Multi-Interlocked Molecular Machines.

    PubMed

    Legigan, Thibaut; Riss-Yaw, Benjamin; Clavel, Caroline; Coutrot, Frédéric

    2016-06-20

    The efficient synthesis and very easy isolation of dibenzo[24]crown-8-based [2]pseudorotaxane building blocks that contain an active ester motif at the extremity of the encircled molecular axle and an ammonium moiety as a template for the dibenzo[24]crown-8 is reported. The active ester acts both as a semistopper for the [2]pseudorotaxane species and as an extensible extremity. Among the various investigated active ester moieties, those that allow for the slippage process are given particular focus because this strategy produces fewer side products. Extension of the selected N-hydroxysuccinimide ester based pseudorotaxane building block by using either a mono- or a diamino compound, both containing a triazolium moiety, is also described. These provide a pH-dependent two-station [2]rotaxane molecular machine and a palindromic [3]rotaxane molecular machine, respectively. Molecular machinery on both interlocked compounds through variation of pH was studied and characterized by means of NMR spectroscopy. PMID:27239975

  13. Block Copolymers with a Twist

    SciTech Connect

    Ho, R.; Chiang, Y; Chen, C; Wang, H; Hasegawa, H; Akasaka, S; Thomas, E; Burger, C; Hsiao, B

    2009-01-01

    Chiral block copolymers (BCPs*) comprising chiral entities were designed to fabricate helical architectures (i.e., twisted morphologies) from self-assembly. A new helical phase (H*) with P622 symmetry was discovered in the self-assembly of poly(styrene)-b-poly(l-lactide) (PS-PLLA) BCPs*. Hexagonally packed, interdigitated PLLA helical microdomains in a PS matrix were directly visualized by electron tomography. The phase diagram of the PS-PLLA BCPs* was also established. Phase transitions from the H* phase to the stable cylinder and gyroid phases were found after long-time annealing, suggesting that the H* is a long-lived metastable phase. In contrast to racemic poly(styrene)-b-poly(d,l-lactide) BCPs, chiral interaction significantly enhances the incompatibility between achiral PS and chiral PLLA blocks in the PS-PLLA BCPs* and can be estimated through the determination of the interaction parameter.

  14. A bracket approach to improve the stability and gas sorption performance of a metal-organic framework via in situ incorporating the size-matching molecular building blocks.

    PubMed

    Chen, Di-Ming; Tian, Jia-Yue; Liu, Chun-Sen; Du, Miao

    2016-06-28

    Incorporating the in situ formed size-matching molecular building blocks (MBBs) into the open channels will remarkably improve the robustness and gas sorption performance of an evacuated metal-organic framework. As a result, such MBBs can transfer the open metal sites from the framework walls to the channel centers and separate the large channels into multiple smaller voids, leading to a molecular sieving effect and high-performance gas-separation of the modified material. PMID:27301546

  15. A polyhedral metal-organic framework based on the supermolecular building block strategy exhibiting high performance for carbon dioxide capture and separation of light hydrocarbons.

    PubMed

    Wang, Dongmei; Liu, Bing; Yao, Shuo; Wang, Tao; Li, Guanghua; Huo, Qisheng; Liu, Yunling

    2015-10-25

    By using the supermolecular building block (SBB) strategy, a polyhedron-based metal-organic framework (PMOF), which features three types of cages with multiple sizes and shapes, has been synthesized. It exhibits high performance for CO2 capture (170 cm(3) g(-1) at 273 K under 1 bar) and selectivity of CO2/CH4 (9.4) and C3H8/CH4 (271.5). PMID:26339689

  16. Onset of the Electronic Absorption Spectra of Isolated and π-Stacked Oligomers of 5,6-Dihydroxyindole: An Ab Initio Study of the Building Blocks of Eumelanin.

    PubMed

    Tuna, Deniz; Udvarhelyi, Anikó; Sobolewski, Andrzej L; Domcke, Wolfgang; Domratcheva, Tatiana

    2016-04-14

    Eumelanin is a naturally occurring skin pigment which is responsible for developing a suntan. The complex structure of eumelanin consists of π-stacked oligomers of various indole derivatives, such as the monomeric building block 5,6-dihydroxyindole (DHI). In this work, we present an ab initio wave-function study of the absorption behavior of DHI oligomers and of doubly and triply π-stacked species of these oligomers. We have simulated the onset of the electronic absorption spectra by employing the MP2 and the linear-response CC2 methods. Our results demonstrate the effect of an increasing degree of oligomerization of DHI and of an increasing degree of π-stacking of DHI oligomers on the onset of the absorption spectra and on the degree of red-shift toward the visible region of the spectrum. We find that π-stacking of DHI and its oligomers substantially red-shifts the onset of the absorption spectra. Our results also suggest that the optical properties of biological eumelanin cannot be simulated by considering the DHI building blocks alone, but instead the building blocks indole-semiquinone and indole-quinone have to be considered as well. This study contributes to advancing the understanding of the complex photophysics of the eumelanin biopolymer. PMID:27005558

  17. 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. PMID:26221940

  18. Unified Synthesis of C1-C19 Building Blocks of Halichondrins via Selective Activation/Coupling of Polyhalogenated Nucleophiles in (Ni)/Cr-Mediated Reactions.

    PubMed

    Li, Jingwei; Yan, Wuming; Kishi, Yoshito

    2015-05-20

    A unified synthesis of the C1-C19 building blocks 8-10 of halichondrins A-C was developed from the common synthetic intermediates 26a,b. Acetylenic ketones 26a,b were in turn synthesized via selective activation/coupling of polyhalogenated nucleophiles 23a,b with aldehyde 11 in a (Ni)/Cr-mediated coupling reaction. Compared with Ni/Cr-mediated couplings of vinyl iodides and aldehydes, this (Ni)/Cr-mediated coupling exhibited two unique features. First, the coupling was found to proceed with a trace amount or no added Ni-catalyst. Second, TES-Cl, a dissociating agent to regenerate the Cr-catalyst, was found to give a better yield than Zr(Cp)2Cl2. An adjustment of the oxidation state was required to transform acetylenic ketones 26a,b into C1-C19 building blocks 8 and 9 of halichondrins A and B, respectively. In the halichondrin B series, a hydroxyl-directed (Me)4NBH(OAc)3 reduction of E- and Z-β-alkoxy-enones 30 was found cleanly to achieve the required transformation, whereas a DMDO oxidation of E-vinylogous ester 27 allowed to introduce the C13 hydroxyl group with a high stereoselectivity in the halichondrin A series. In the halichondrin C series, Hf(OTf)4 was used to convert the double oxy-Michael product 28 into C1-C19 building block 10. PMID:25923790

  19. 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

  20. 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

  1. Supramolecular architectures of novel chromium(III) oxalate complexes: steric effects of the ligand size and building-blocks approach.

    PubMed

    Androš, Lidija; Jurić, Marijana; Molčanov, Krešimir; Planinić, Pavica

    2012-12-28

    Five new oxalate complexes of chromium(III), [Hphen][Cr(phen)(C(2)O(4))(2)]·2H(2)O (1), [Cr(phen)(2)(C(2)O(4))][Cr(phen)(C(2)O(4))(2)]·3H(2)O (2), [Cr(phen)(2)(C(2)O(4))]NO(3)·H(2)C(2)O(4)·H(2)O (3), [Cr(bpy)(2)(C(2)O(4))][Cr(bpy)(C(2)O(4))(2)]·3H(2)O (4) and [Cr(bpy)(2)(C(2)O(4))]NO(3)·1/2H(2)C(2)O(4)·4H(2)O (5) (phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine), were prepared by using an (oxalato)tantalate(V) solution as a source of oxalate ligands. The compounds contain either the discrete mononuclear [Cr(L)(2)(C(2)O(4))](+) cation [L = phen (3); L = bpy (5)] or the discrete mononuclear [Cr(L)(C(2)O(4))(2)](-) anion [L = phen (1)], or both types of mononuclear ions [L = phen (2); L = bpy (4)]. The crystal structures are dominated by the hydrogen-bonding and π···π-stacking interactions that give rise to the overall two- (compounds 1, 2, 4, 5) or three-dimensional (compound 3) architectures. Compounds 2 and 4 represent a borderline case between isostructurality and non-isostructurality; they exhibit an analogous packing of the cation and the anion units, but the crystallization water molecules occupy different positions - due to a difference in size between the phen and bpy ligands. The influence of steric factors is evident also in the case of 3 and 5, which, despite very similar chemical formulae, exert a completely different packing of the constituents. By the self-assembling of 1 and 4, used as building blocks in the reaction with calcium(II) cations, the heterobimetallic polymeric compounds {[CaCr(2)(phen)(2)(C(2)O(4))(4)]·5H(2)O}(n) (6) and {[CaCr(2)(bpy)(2)(C(2)O(4))(4)]·0.83H(2)O}(n) (7) were obtained. The crystal structure of 7 is reported: the [Cr(bpy)(C(2)O(4))(2)](-) unit, through the two oxalate groups, acts as a chelating ligand towards Ca cations, resulting in heterometallic one-dimensional double zigzag chains, formed of diamond-shaped units. The characterization of the compounds obtained was accomplished by the spectroscopy and

  2. An fMRI Study of the Impact of Block Building and Board Games on Spatial Ability.

    PubMed

    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

  3. 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

  4. 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. PMID:25800712

  5. Ab initio computational investigation of physisorption of molecular hydrogen on achiral single-walled carbon nanotubes.

    PubMed

    Ferre-Vilaplana, A

    2005-06-01

    Using relatively approximated methods, physisorption of molecular hydrogen on single-walled carbon nanotubes (SWCNTs) as a mechanism to develop hydrogen storage systems has been only partially investigated in literature. Here, we use ab initio molecular-orbital theory, at benchmark quality level, to provide a more complete description about the mentioned mechanism. Physisorption inside and outside achiral-armchair and zigzag-SWCNTs, in the range of diameters from about 6 A-chiral vectors (5,5) and (8,0)-to more than 30 A-chiral vectors (30,30) and (40,0)-was examined. Perpendicular, longitudinal, and transversal configurations, with the hydrogen molecule centered on an aromatic ring, were taken into account. SWCNTs were modeled as curved coronenelike (C24H12) graphene sheets. Local modeling strategies, using more complete basis sets for the adsorbate and for the nearest atoms to the adsorbate than for the lion's share of the substrate, at the Moller-Plesset second-order correlation level, were selected for numerical treatment. Basis-set superposition errors were corrected by means of the counterpoise method of Bois and Bernardi. It was found that physisorption of molecular hydrogen on SWCNTs would depend mainly on the diameter being virtually independent of the chirality. Lowest physisorption energies, up to 20% less than that on planar graphene, would be reached outside nanotubes in the range of diameters of 6-10 A. For hydrogen storage purposes, highest physisorption energies, up to 40% greater than that on planar graphene, but not more, would be reached inside nanotubes in the relatively narrow range of diameters of 10-20 A. Finally, for diameters from 20 A onwards physisorption of molecular hydrogen on SWCNTs would be in the range of +/-10% of that on planar graphene. To our knowledge, this would be the most complete and realistic theoretical investigation of the target physisorption mechanism to date. PMID:15974779

  6. Stereoselective Rh-Catalyzed Hydrogenative Desymmetrization of Achiral Substituted 1,4-Dienes.

    PubMed

    Fernández-Pérez, Héctor; Lao, Joan R; Vidal-Ferran, Anton

    2016-06-17

    Highly efficient catalytic stereoselective hydrogenative desymmetrization reactions mediated by rhodium complexes derived from enantiopure phosphine-phosphite (P-OP) ligands are described. The highest performing ligand, which contains a TADDOL-derived phosphite fragment [TADDOL = (2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanol)], presented excellent catalytic properties for the desymmetrization of a set of achiral 1,4-dienes, providing access to the selective formation of a variety of enantioenriched secondary and tertiary alcohols (six examples, up to 92% ee). PMID:27230728

  7. Spontaneous Mirror-Symmetry Breaking in Isotropic Liquid Phases of Photoisomerizable Achiral Molecules.

    PubMed

    Alaasar, Mohamed; Prehm, Marko; Cao, Yu; Liu, Feng; Tschierske, Carsten

    2016-01-01

    Spontaneous mirror-symmetry breaking is of fundamental importance in science as it contributes to the development of chiral superstructures and new materials and has a major impact on the discussion around the emergence of uniform chirality in biological systems. Herein we report chirality synchronization, leading to spontaneous chiral conglomerate formation in isotropic liquids of achiral and photoisomerizable azobenzene-based rod-like molecules. The position of fluorine substituents at the aromatic core is found to have a significant effect on the stability and the temperature range of these chiral liquids. Moreover, these liquid conglomerates occur in a new phase sequence adjacent to a 3D tetragonal mesophase. PMID:26490058

  8. Controlled chiral supramolecular assemblies of water soluble achiral porphyrins induced by chiral counterions.

    PubMed

    Rananaware, Anushri; La, Duong Duc; Al Kobaisi, Mohammad; Bhosale, Rajesh S; Bhosale, Sidhanath V; Bhosale, Sheshanath V

    2016-08-11

    We demonstrate a controlled chiral supramolecular assembly of achiral porphyrins induced by chiral d- and l-arginine (Arg) in water. Induction of chirality was confirmed by circular dichroism. TEM and SEM images confirm that these twisted ribbons are indeed formed by right- and left-handed helices with d- and l-Arg in water, respectively. The chiral assembly pathways described here are hierarchical, opening up the possibility that simple changes on microscopic (nm) length scales can be used to control structures on macroscopic (mm) length scales. PMID:27464524

  9. A homochiral 3D covalent framework assembled from vertical chiral layers with achiral bridging ligands

    NASA Astrophysics Data System (ADS)

    Wang, Xinlong; Qin, Chao; Wang, Enbo; Xu, Lin

    2005-02-01

    A novel metal-organic coordination polymer, [Cd(HPT) 2(4,4'-bpy)] n (PT=phthalate), has been hydrothermally synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. Colorless crystals crystallized in the tetragonal system, space group I4 122, a=8.294(5), b=8.294(5), c=33.7535(17) Å, V=2321.8(18) Å 3, Z=4 and R=0.0207. The structure of the compound exhibiting a homochiral 3D covalent framework based on achiral bridging ligands has been constructed by an alternating assembly of vertical chiral layers consisting of homochiral helices.

  10. Layer thinning transition in an achiral four-ring hockey stick shaped liquid crystal

    NASA Astrophysics Data System (ADS)

    Paul, Manoj Kr.; Nath, Rahul K.; Moths, Brian; Pan, LiDong; Wang, Shun; Deb, Rajdeep; Shen, Yongqiang; Rao, Nandiraju V. S.; Huang, C. C.

    2012-12-01

    Depolarized reflected light microscopy and high resolution optical reflectivity measurements have been conducted on free-standing films of an achiral four-ring hockey stick shaped liquid crystal exhibiting SmA-B2-SmX* transition sequence. A layer thinning transition above the bulk isotropic-SmA phase transition has been observed. This behaviour was highly irreproducible, indicating an irregular layer thinning transition. From optical reflectivity data, both thickness of the free-standing films and the smectic interlayer spacing were determined. This is the first report of the layer thinning transition in a hockey stick shaped liquid crystal.

  11. 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.

  12. End-Group-Functionalized Poly(α-olefinates) as Non-Polar Building Blocks: Self-Assembly of Sugar-Polyolefin Hybrid Conjugates.

    PubMed

    Thomas, Tessy S; Hwang, Wonseok; Sita, Lawrence R

    2016-04-01

    Living coordinative chain-transfer polymerization of α-olefins, followed by chemical functionalization of a Zn(polymeryl)2 intermediate, provides entry to end-group functionalized poly(α-olefinates) (x-PAOs) that can serve as a new class of non-polar building block with tailorable occupied volumes. Application of these x-PAOs for the synthesis and self-assembly of sugar-polyolefin hybrid conjugates demonstrate the ability to manipulate the morphology of the ultra-thin film nanostructure through variation in occupied volume of the x-PAO domain. PMID:26961338

  13. Desilylative activation of TMSCN in chemoselective Strecker-Ugi type reaction: functional fused imidazoles as building blocks as an entry route to annulated purines.

    PubMed

    Guchhait, Sankar K; Chaudhary, Vikas

    2014-09-14

    A pathway of desilylative activation of TMSCN as a functional isonitrile equivalent, and DABCO-THF as an appropriate system for activation in a chemoselective Strecker-Ugi type reaction, has rendered ethyl glyoxalate and various heterocyclic-2-amidines as feasible substrates, and afforded the successful synthesis of 3-amino-2-carboxyethyl substituted fused imidazoles as useful building blocks. This class of functional scaffold has provided, via construction of the fused pyrimidinone motif, the synthesis of biologically important C8-N9 annulated purines, adenines and their oxo/thio analogs. This new approach is convenient and flexible for the preparation of versatile purine-condensed heterocycles. PMID:25032666

  14. Role of pseudoephedrine as chiral auxiliary in the "acetate-type" aldol reaction with chiral aldehydes; asymmetric synthesis of highly functionalized chiral building blocks.

    PubMed

    Ocejo, Marta; Carrillo, Luisa; Vicario, Jose L; Badía, Dolores; Reyes, Efraim

    2011-01-21

    We have studied in depth the aldol reaction between acetamide enolates and chiral α-heterosubstituted aldehydes using pseudoephedrine as chiral auxiliary under double stereodifferentiation conditions, showing that high diastereoselectivities can only be achieved under the matched combination of reagents and provided that the α-heteroatom-containing substituent of the chiral aldehyde is conveniently protected. Moreover, the obtained highly functionalized aldols have been employed as very useful starting materials for the stereocontrolled preparation of other interesting compounds and chiral building blocks such as pyrrolidines, indolizidines, and densely functionalized β-hydroxy and β-amino ketones using simple and high-yielding methodologies. PMID:21188970

  15. 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

  16. Dinuclear Zinc-Catalyzed Asymmetric Desymmetrization of Acyclic 2-Substituted-1,3-Propanediols: A Powerful Entry into Chiral Building Blocks

    PubMed Central

    Trost, Barry M.; Malhotra, Sushant; Mino, Takashi; Rajapaksa, Naomi S.

    2008-01-01

    The asymmetric acylation of meso 2-substituted-1,3-propanediols using an amphoteric chiral dinuclear zinc catalyst is described. It is has been demonstrated that both 2-alkyl- and 2-aryl-1,3-propanediols can be desymmetrized in high yields and enantioselectivities using the same family of ligands. Given that both antipodes of the chiral catalyst are available, both enantiomers of the desymmetrized product can be obtained from the same starting material. The synthetic utility of the desymmetrized products has been demonstrated by the synthesis of several chiral building blocks with high enantiomeric purities. PMID:18655088

  17. Right handed chiral superstructures from achiral molecules: self-assembly with a twist

    NASA Astrophysics Data System (ADS)

    Anuradha; La, Duong Duc; Al Kobaisi, Mohammad; Bhosale, Sheshanath V.

    2015-10-01

    The induction and development of chiral supramolecular structures from hierarchical self-assembly of achiral compounds is closely related to the evolution of life and the chiral amplification found in nature. Here we show that the combination of achiral tetraphenylethene (TPE) an AIE-active luminophore bearing four long alkyl chains via amide linkage allows the entire process of induction and control of supramolecular chirality into well-defined uniform right-handed twisted superstructures via solvent composition and polarity, i.e. solvophobic effect. We showed that the degree of twist and the pitch of the ribbons can be controlled to one-handed helical structure via solvophobic effects. The twisted superstructure assembly was visualised by scanning electron microscope (SEM) and transmission electron microscopy (TEM), furthermore, circular dichroism (CD) confirms used to determine controlled right-handed assembly. This controlled assembly of an AIE-active molecule can be of practical value; for example, as templates for helical crystallisation, catalysis and a chiral mechanochromic luminescent superstructure formation.

  18. Right handed chiral superstructures from achiral molecules: self-assembly with a twist

    PubMed Central

    Anuradha, A; La, Duong Duc; Al Kobaisi, Mohammad; Bhosale, Sheshanath V.

    2015-01-01

    The induction and development of chiral supramolecular structures from hierarchical self-assembly of achiral compounds is closely related to the evolution of life and the chiral amplification found in nature. Here we show that the combination of achiral tetraphenylethene (TPE) an AIE-active luminophore bearing four long alkyl chains via amide linkage allows the entire process of induction and control of supramolecular chirality into well-defined uniform right-handed twisted superstructures via solvent composition and polarity, i.e. solvophobic effect. We showed that the degree of twist and the pitch of the ribbons can be controlled to one-handed helical structure via solvophobic effects. The twisted superstructure assembly was visualised by scanning electron microscope (SEM) and transmission electron microscopy (TEM), furthermore, circular dichroism (CD) confirms used to determine controlled right-handed assembly. This controlled assembly of an AIE-active molecule can be of practical value; for example, as templates for helical crystallisation, catalysis and a chiral mechanochromic luminescent superstructure formation. PMID:26493294

  19. 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

    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

  20. Synthesis of a Glucuronic Acid-Containing Thioglycoside Trisaccharide Building Block and Its Use in the Assembly of Cryptococcus Neoformans Capsular Polysaccharide Fragments.

    PubMed

    Guazzelli, Lorenzo; Ulc, Rebecca; Oscarson, Stefan

    2015-12-01

    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

  1. 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

  2. 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

  3. Spontaneous formation of organic helical architectures through dynamic covalent chemistry.

    PubMed

    Li, Wenfang; Dong, Zeyuan; Zhu, Junyan; Luo, Quan; Liu, Junqiu

    2014-12-01

    The spontaneous formation of organic helical structures, accompanied with an amplification of chirality, by dynamic covalent bonds between achiral and chiral building blocks is reported. PMID:25325888

  4. Finding the Right Architect: A Primer for Educational Design. A Volume in the Building Blocks to Better Learning Series.

    ERIC Educational Resources Information Center

    Vickery, Robert L.

    This booklet offers suggestions to those involved in planning school construction efforts, in order to help them better understand the process of designing and building such facilities, particularly with regard to the role of the architect. The text defines what good architecture is and what it should accomplish. It considers the services needed,…

  5. From HORSA Huts to ROSLA Blocks: The School Leaving Age and the School Building Programme in England, 1943-1972

    ERIC Educational Resources Information Center

    Cowan, Steven; McCulloch, Gary; Woodin, Tom

    2012-01-01

    This paper examines the connections between the school building programme in England and the raising of the school leaving age (ROSLA) from 14 to 15 in 1947 and then to 16 in 1972. These two major developments were intended to help to ensure the realisation of "secondary education for all" in the postwar period. The combination led in practice to…

  6. 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.

  7. Circularly polarized laser emission induced in isotropic and achiral dye systems.

    PubMed

    Cerdán, Luis; García-Moreno, Sara; Costela, Angel; García-Moreno, Inmaculada; de la Moya, Santiago

    2016-01-01

    The production of efficient, tunable, and switchable circularly polarized laser emission would have far reaching implications in optical communications or biophotonics. In this work, it is demonstrated the direct generation of circularly polarized (CP) laser emission in achiral and isotropic dye laser systems without the use of extracavity polarizing elements, and without resorting to chiral dyes, chiral liquid crystal matrices, or interferometric methods. The origin of this ellipticity arises from the dynamic birefringence induced by the strong and polarized laser pumping and the subsequent orientation anisotropy of the excited molecular dipoles. A complete polarimetric characterization of the polarization state of conventional dye laser oscillators as a function of different experimental parameters is performed and it is shown that the generated light always possesses a certain level of circularity that changes in a distinctive way with pump energy and polarization. These results demonstrate that it is possible to generate and modulate CP laser light from efficient and photostable conventional laser dyes. PMID:27350073

  8. Circularly polarized laser emission induced in isotropic and achiral dye systems

    NASA Astrophysics Data System (ADS)

    Cerdán, Luis; García-Moreno, Sara; Costela, Angel; García-Moreno, Inmaculada; de La Moya, Santiago

    2016-06-01

    The production of efficient, tunable, and switchable circularly polarized laser emission would have far reaching implications in optical communications or biophotonics. In this work, it is demonstrated the direct generation of circularly polarized (CP) laser emission in achiral and isotropic dye laser systems without the use of extracavity polarizing elements, and without resorting to chiral dyes, chiral liquid crystal matrices, or interferometric methods. The origin of this ellipticity arises from the dynamic birefringence induced by the strong and polarized laser pumping and the subsequent orientation anisotropy of the excited molecular dipoles. A complete polarimetric characterization of the polarization state of conventional dye laser oscillators as a function of different experimental parameters is performed and it is shown that the generated light always possesses a certain level of circularity that changes in a distinctive way with pump energy and polarization. These results demonstrate that it is possible to generate and modulate CP laser light from efficient and photostable conventional laser dyes.

  9. Entropy-Driven Chiral Order in a System of Achiral Bent Particles

    NASA Astrophysics Data System (ADS)

    Greco, Cristina; Ferrarini, Alberta

    2015-10-01

    Why should achiral particles organize into a helical structure? Here, using theory and molecular dynamics simulations we show that at high concentration crescent-shaped particles interacting through a purely repulsive potential form the twist-bend nematic phase, which features helical order of the twofold symmetry axes of particles, with doubly degenerate handedness. Spontaneous breaking of the chiral symmetry is driven by the entropic gain that derives from the decrease in excluded volume in the helical arrangement. Crucial to this purpose is the concave shape of particles. This study is based on a general formulation of the Onsager theory, which includes biaxiality and polarity of phase and particles, in addition to the space modulation of order. Molecular dynamics simulations corroborate the theoretical predictions and provide further insights into the structure of the helical phase.

  10. Tuning of giant 2D-chiroptical response using achiral metasurface integrated with graphene.

    PubMed

    Cao, Tun; Wei, Chen-Wei; Mao, Li-Bang; Wang, Shuai

    2015-07-13

    Tuning the chiroptical response of a molecule is crucial for detecting the material's chirality. Here, we demonstrate a pronounced circular conversion dichroism (CCD) by using an achiral metasurface (AMS) which is composed of a rectangular reflectarray of Au squares separated from a continuous Au film by a dielectric interlayer. This extrinsically 2D chirality originates from the mutual orientation between the AMS and oblique incident wave. The AMS is further incorporated with graphene to tune the CCD spectra in the mid-infrared (MIR) region by electrically modulating the graphene's Fermi level. This approach offers a high fabrication tolerance and will be a promising candidate for controlling electromagnetic (EM) waves in the MIR region from 1500 to 3000 nm. PMID:26191920

  11. Inhibition of acetylcholinesterase by 14 achiral and five chiral imidazole derivates.

    PubMed

    Kovárová, Markéta; Komers, Karel; Stepánková, Sárka; Cegan, Alexander

    2010-08-01

    Homological series of 14 achiral derivates and series of five chiral derivates of imidazole were tested in vitro as inhibitors of hydrolysis of acetylcholine using enzyme preparation of acetylcholinesterase from electric eel. The batch stirred reactor at 25 degrees C, pH 8 (phosphate buffer), ionic strength 0.11 M and catalytic activity of the enzyme preparation 0.14 U ml(-1) of the reaction mixture were used. The temporal dependences of actual concentrations of acetylcholine, choline and acetic acid were determined by an original HPLC method. For all used inhibitors, these time dependences conform with the probability of more than 90% to the model of competitive irreversible inhibition. All kinetic constants including k(3) defining the rate of inhibition (0.38-5.3M(-1)s(-1)) and qualified estimation of the absolute acetylcholinesterase concentration in the reaction mixture (40-110 nM) were determined. PMID:20335028

  12. Circularly polarized laser emission induced in isotropic and achiral dye systems

    PubMed Central

    Cerdán, Luis; García-Moreno, Sara; Costela, Angel; García-Moreno, Inmaculada; de la Moya, Santiago

    2016-01-01

    The production of efficient, tunable, and switchable circularly polarized laser emission would have far reaching implications in optical communications or biophotonics. In this work, it is demonstrated the direct generation of circularly polarized (CP) laser emission in achiral and isotropic dye laser systems without the use of extracavity polarizing elements, and without resorting to chiral dyes, chiral liquid crystal matrices, or interferometric methods. The origin of this ellipticity arises from the dynamic birefringence induced by the strong and polarized laser pumping and the subsequent orientation anisotropy of the excited molecular dipoles. A complete polarimetric characterization of the polarization state of conventional dye laser oscillators as a function of different experimental parameters is performed and it is shown that the generated light always possesses a certain level of circularity that changes in a distinctive way with pump energy and polarization. These results demonstrate that it is possible to generate and modulate CP laser light from efficient and photostable conventional laser dyes. PMID:27350073

  13. Spectroscopic sensing of reflection optical activity in achiral AgGaS₂.

    PubMed

    Arteaga, Oriol

    2015-09-15

    Optical activity is a fundamental effect of electrodynamics that was discovered more than 200 years ago. While optical activity is typically recognized by the rotation of the polarization of light as it propagates through a bulk medium, in certain configurations, the specular reflection of light on the surface of a material is also sensitive to its optical activity. Here, we show that the ellipsometric analysis of the light reflected at the surface of a gyrotropic but achiral crystal of AgGaS(2) allows the spectroscopic determination of its optical activity above the bandgap, where transmission methods are not applicable. This is the first clear spectroscopic determination of reflection optical activity in a crystal, and the values obtained are, to the best of our knowledge, the largest ever reported for a natural material. We also demonstrate that normal incidence transmission and reflection measurements probe different aspects of optical activity. PMID:26371915

  14. 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) . PMID:26097019

  15. 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. PMID:26663513

  16. 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.

  17. 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. PMID:23448184

  18. Self-Assembling Nano-Architectures Created from a Protein Nano-Building Block Using an Intermolecularly Folded Dimeric de Novo Protein.

    PubMed

    Kobayashi, Naoya; Yanase, Keiichi; Sato, Takaaki; Unzai, Satoru; Hecht, Michael H; Arai, Ryoichi

    2015-09-01

    The design of novel proteins that self-assemble into supramolecular complexes is an important step in the development of synthetic biology and nanotechnology. Recently, we described the three-dimensional structure of WA20, a de novo protein that forms an intermolecularly folded dimeric 4-helix bundle (PDB code 3VJF ). To harness the unusual intertwined structure of WA20 for the self-assembly of supramolecular nanostructures, we created a protein nanobuilding block (PN-Block), called WA20-foldon, by fusing the dimeric structure of WA20 to the trimeric foldon domain of fibritin from bacteriophage T4. The WA20-foldon fusion protein was expressed in the soluble fraction in Escherichia coli, purified, and shown to form several homooligomeric forms. The stable oligomeric forms were further purified and characterized by a range of biophysical techniques. Size exclusion chromatography, multiangle light scattering, analytical ultracentrifugation, and small-angle X-ray scattering (SAXS) analyses indicate that the small (S form), middle (M form), and large (L form) forms of the WA20-foldon oligomers exist as hexamer (6-mer), dodecamer (12-mer), and octadecamer (18-mer), respectively. These findings suggest that the oligomers in multiples of 6-mer are stably formed by fusing the interdigitated dimer of WA20 with the trimer of foldon domain. Pair-distance distribution functions obtained from the Fourier inversion of the SAXS data suggest that the S and M forms have barrel- and tetrahedron-like shapes, respectively. These results demonstrate that the de novo WA20-foldon is an effective building block for the creation of self-assembling artificial nanoarchitectures. PMID:26120734

  19. From Coronal Observations to MHD Simulations, the Building Blocks for 3D Models of Solar Flares (Invited Review)

    NASA Astrophysics Data System (ADS)

    Janvier, M.; Aulanier, G.; Démoulin, P.

    2015-12-01

    Solar flares are energetic events taking place in the Sun's atmosphere, and their effects can greatly impact the environment of the surrounding planets. In particular, eruptive flares, as opposed to confined flares, launch coronal mass ejections into the interplanetary medium, and as such, are one of the main drivers of space weather. After briefly reviewing the main characteristics of solar flares, we summarise the processes that can account for the build-up and release of energy during their evolution. In particular, we focus on the development of recent 3D numerical simulations that explain many of the observed flare features. These simulations can also provide predictions of the dynamical evolution of coronal and photospheric magnetic field. Here we present a few observational examples that, together with numerical modelling, point to the underlying physical mechanisms of the eruptions.

  20. 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

  1. 2,6-Dipicolinoylbis(N,N-dialkylthioureas) as versatile building blocks for oligo- and polynuclear architectures.

    PubMed

    Nguyen, H H; Jegathesh, J J; Takiden, A; Hauenstein, D; Pham, C T; Le, C D; Abram, U

    2016-06-28

    Similar reactions of 2,6-dipicolinoylbis(N,N-diethylthiourea) (H2L(a)) with: (i) Ni(NO3)2·6H2O, (ii) a mixture of Ni(NO3)2·6H2O and AgNO3, (iii) a mixture of Ni(OAc)2·4H2O and PrCl3·7H2O and (iv) a mixture of Ni(OAc)2·4H2O and BaCl2·2H2O give the binuclear complex [Ni2(L(a))2(MeOH)(H2O)], the polymeric compound [NiAg2(L(a))2]∞, and the heterobimetallic complexes [Ni2Pr(L(a))2(OAc)3] and [Ni2Ba(L(a))3], respectively. The obtained assemblies can be used for the build up of supramolecular polymers by means of weak and medium intermolecular interactions. Two prototype examples of such compounds, which are derived from the trinuclear complexes of the types [MLn(III)(L)2(OAc)3] and [MBa(L)3], are described with the compounds {[CuDy(III)(L(a))2(p-O2C-C6H4-CO2)(MeOH)4]Cl}∞ and [MnBa(MeOH)(L(b))3]∞, H2L(b) = 2,6-dipicolinoylbis(N,N-morpholinoylthiourea). PMID:27292266

  2. CMOL/CMOS hardware architectures and performance/price for Bayesian memory - The building block of intelligent systems

    NASA Astrophysics Data System (ADS)

    Zaveri, Mazad Shaheriar

    implementation. We later use this methodology to investigate the hardware implementations of cortex-scale spiking neural system, which is an approximate neural equivalent of BICM based cortex-scale system. The results of this investigation also suggest that CMOL is a promising candidate to implement such large-scale neuromorphic systems. In general, the assessment of such hypothetical baseline hardware architectures provides the prospects for building large-scale (mammalian cortex-scale) implementations of neuromorphic/Bayesian/intelligent systems using state-of-the-art and beyond state-of-the-art silicon structures.

  3. Heart Block

    MedlinePlus

    ... Block Explore Heart Block What Is... Electrical System & EKG Results Types Causes Who Is at Risk Signs & ... heart block. Doctors use a test called an EKG (electrocardiogram) to help diagnose heart block. This test ...

  4. Interfacial organization of achiral porphyrins via unidirectional compression: a general method for chiroptical porphyrin assemblies of selected chirality.

    PubMed

    Zhang, Xiao; Wang, Yanping; Chen, Penglei; Rong, Yunlong; Liu, Minghua

    2016-05-18

    Porphyrins are considered to be important scaffolds bridging supramolecular chemistry and chiral chemistry, where chirality selection via physical effects such as directional stirring and spin-coating has aroused particular interest. Nevertheless, these protocols could only work on a limited number of achiral porphyrins. It still remains a formidable challenge to pave a general avenue for the construction of chiral assemblies using achiral porphyrins. By means of a unique Langmuir-Schaefer (LS) technique of a unidirectional compression configuration, we herein have demonstrated that a series of achiral porphyrins could be facilely organized to form chiral interfacial assemblies of controlled supramolecular chirality. It has been disclosed that such a fascinating chirality selection scenario is intimately related to the direction of the compression-generated vortex-like flow, while the compression speed, one of the most significant parameters of the Langmuir technique, contributes less to this issue. With regard to a surface-pressure-dependent chirality selection phenomenon, it is suggested that the directional vortex-like flow generated by lateral compression might play a role in promoting the preferential growth of chiral assemblies showing an enhanced yet controlled CD signal. Our protocol might be, to some extent, a general method for achieving chiral porphyrin assemblies of controlled chirality. PMID:27156996

  5. 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.

  6. 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. PMID:25923602

  7. A novel chiral phase of achiral hard triangles and an entropy-driven demixing of enantiomers.

    PubMed

    Gantapara, Anjan P; Qi, Weikai; Dijkstra, Marjolein

    2015-11-28

    We investigate the phase behavior of a system of hard equilateral and right-angled triangles in two dimensions using Monte Carlo simulations. Hard equilateral triangles undergo a continuous isotropic-triatic liquid crystal phase transition at packing fraction ϕ = 0.7. Similarly, hard right-angled isosceles triangles exhibit a first-order phase transition from an isotropic fluid phase to a rhombic liquid crystal phase with a coexistence region ϕ ∈ [0.733, 0.782]. Both these liquid crystals undergo a continuous phase transition to their respective close-packed crystal structures at high pressures. Although the particles and their close-packed crystals are both achiral, the solid phases of equilateral and right-angled triangles exhibit spontaneous chiral symmetry breaking at sufficiently high packing fractions. The colloidal triangles rotate either in the clockwise or anti-clockwise direction with respect to one of the lattice vectors for packing fractions higher than ϕχ. As a consequence, these triangles spontaneously form a regular lattice of left- or right-handed chiral holes which are surrounded by six triangles in the case of equilateral triangles and four or eight triangles for right-angled triangles. Moreover, our simulations show a spontaneous entropy-driven demixing transition of the right- and left-handed "enantiomers". PMID:26376756

  8. Numerical study of achiral phase-change metamaterials for ultrafast tuning of giant circular conversion dichroism

    PubMed Central

    Cao, Tun; Wei, Chenwei; Mao, Libang

    2015-01-01

    Control of the polarization of light is highly desirable for detection of material’s chirality since biomolecules have vibrational modes in the optical region. Here, we report an ultrafast tuning of pronounced circular conversion dichroism (CCD) in the mid-infrared (M-IR) region, using an achiral phase change metamaterial (PCMM). Our structure consists of an array of Au squares separated from a continuous Au film by a phase change material (Ge2Sb2Te5) dielectric layer, where the Au square patches occupy the sites of a rectangular lattice. The extrinsically giant 2D chirality appears provided that the rectangular array of the Au squares is illuminated at an oblique incidence, and accomplishes a wide tunable wavelength range between 2664 and 3912 nm in the M-IR regime by switching between the amorphous and crystalline states of the Ge2Sb2Te5. A photothermal model is investigated to study the temporal variation of the temperature of the Ge2Sb2Te5 layer, and shows the advantage of fast transiting the phase of Ge2Sb2Te5 of 3.2 ns under an ultralow incident light intensity of 1.9 μW/μm2. Our design is straightforward to fabricate and will be a promising candidate for controlling electromagnetic (EM) wave in the optical region. PMID:26423517

  9. Numerical study of achiral phase-change metamaterials for ultrafast tuning of giant circular conversion dichroism.

    PubMed

    Cao, Tun; Wei, Chenwei; Mao, Libang

    2015-01-01

    Control of the polarization of light is highly desirable for detection of material's chirality since biomolecules have vibrational modes in the optical region. Here, we report an ultrafast tuning of pronounced circular conversion dichroism (CCD) in the mid-infrared (M-IR) region, using an achiral phase change metamaterial (PCMM). Our structure consists of an array of Au squares separated from a continuous Au film by a phase change material (Ge2Sb2Te5) dielectric layer, where the Au square patches occupy the sites of a rectangular lattice. The extrinsically giant 2D chirality appears provided that the rectangular array of the Au squares is illuminated at an oblique incidence, and accomplishes a wide tunable wavelength range between 2664 and 3912 nm in the M-IR regime by switching between the amorphous and crystalline states of the Ge2Sb2Te5. A photothermal model is investigated to study the temporal variation of the temperature of the Ge2Sb2Te5 layer, and shows the advantage of fast transiting the phase of Ge2Sb2Te5 of 3.2 ns under an ultralow incident light intensity of 1.9 μW/μm(2). Our design is straightforward to fabricate and will be a promising candidate for controlling electromagnetic (EM) wave in the optical region. PMID:26423517

  10. Numerical study of achiral phase-change metamaterials for ultrafast tuning of giant circular conversion dichroism

    NASA Astrophysics Data System (ADS)

    Cao, Tun; Wei, Chenwei; Mao, Libang

    2015-10-01

    Control of the polarization of light is highly desirable for detection of material’s chirality since biomolecules have vibrational modes in the optical region. Here, we report an ultrafast tuning of pronounced circular conversion dichroism (CCD) in the mid-infrared (M-IR) region, using an achiral phase change metamaterial (PCMM). Our structure consists of an array of Au squares separated from a continuous Au film by a phase change material (Ge2Sb2Te5) dielectric layer, where the Au square patches occupy the sites of a rectangular lattice. The extrinsically giant 2D chirality appears provided that the rectangular array of the Au squares is illuminated at an oblique incidence, and accomplishes a wide tunable wavelength range between 2664 and 3912 nm in the M-IR regime by switching between the amorphous and crystalline states of the Ge2Sb2Te5. A photothermal model is investigated to study the temporal variation of the temperature of the Ge2Sb2Te5 layer, and shows the advantage of fast transiting the phase of Ge2Sb2Te5 of 3.2 ns under an ultralow incident light intensity of 1.9 μW/μm2. Our design is straightforward to fabricate and will be a promising candidate for controlling electromagnetic (EM) wave in the optical region.

  11. Mechanical resolution of chiral objects in achiral media: where is the size limit?

    PubMed

    Tencer, Michal; Bielski, Roman

    2011-02-01

    Macroscopic chiral objects (boats and planes with turned rudders, shoes, etc.) get separated from their mirror-image counterparts by motion in achiral media. However, chiral molecules are not enantio-differentiated without the presence of a chiral environment, which may be due to other chiral molecules in the medium. This article explores the reasons of this micro/macro difference as well as the size borderline between the two regimes. There are two major demarcation lines, both related to the object's chaotic thermal motion. The first one is due to destruction of the necessary spatial orientation by the fast rotational diffusion. Only particles larger than 1 μm can maintain their original orientation for 1 sec or longer. For smaller particles, an additional external orienting factor, e.g., a strong electric field has to be applied. The second limitation is defined by the ratio of the hydrodynamic separation of the enantiomers (which is directly proportional to time) to their displacement due to the translational Brownian motion (which is proportional to square root of time). On the laboratory time scales (up to a year), the chiral objects have to be larger than 0.25 μm to be resolved. On evolutionary time scales, much smaller object could be resolved. For enantiomers approaching the molecular size, periods comparable to the age of the universe would be required. PMID:20803496

  12. Chiral and Achiral Nanodumbbell Dimers: The Effect of Geometry on Plasmonic Properties.

    PubMed

    Smith, Kyle W; Zhao, Hangqi; Zhang, Hui; Sánchez-Iglesias, Ana; Grzelczak, Marek; Wang, Yumin; Chang, Wei-Shun; Nordlander, Peter; Liz-Marzán, Luis M; Link, Stephan

    2016-06-28

    Metal nanoparticles with a dumbbell-like geometry have plasmonic properties similar to those of their nanorod counterparts, but the unique steric constraints induced by their enlarged tips result in distinct geometries when self-assembled. Here, we investigate gold dumbbells that are assembled into dimers within polymeric micelles. A single-particle approach with correlated scanning electron microscopy and dark-field scattering spectroscopy reveals the effects of dimer geometry variation on the scattering properties. The dimers are prepared using exclusively achiral reagents, and the resulting dimer solution produces no detectable ensemble circular dichroism response. However, single-particle circular differential scattering measurements uncover that this dimer sample is a racemic mixture of individual nanostructures with significant positive and negative chiroptical signals. These measurements are complemented with detailed simulations that confirm the influence of various symmetry elements on the overall peak resonance energy, spectral line shape, and circular differential scattering response. This work expands the current understanding of the influence self-assembled geometries have on plasmonic properties, particularly with regard to chiral and/or racemic samples which may have significant optical activity that may be overlooked when using exclusively ensemble characterization techniques. PMID:27172606

  13. Continuous Rotation of Achiral Nematic Liquid Crystal Droplets Driven by Heat Flux

    NASA Astrophysics Data System (ADS)

    Ignés-Mullol, Jordi; Poy, Guilhem; Oswald, Patrick

    2016-07-01

    Suspended droplets of cholesteric (chiral nematic) liquid crystals spontaneously rotate in the presence of a heat flux due to a temperature gradient, a phenomenon known as the Lehmann effect. So far, it is not clear whether this effect is due to the chirality of the phase and the molecules or only to the chirality of the director field. Here, we report the continuous rotation in a temperature gradient of nematic droplets of a lyotropic chromonic liquid crystal featuring a twisted bipolar configuration. The achiral nature of the molecular components leads to a random handedness of the spontaneous twist, resulting in the coexistence of droplets rotating in the two senses, with speeds proportional to the temperature gradient and inversely proportional to the droplet radius. This result shows that a macroscopic twist of the director field is sufficient to induce a rotation of the droplets, and that the phase and the molecules do not need to be chiral. This suggests that one can also explain the Lehmann rotation in cholesteric liquid crystals without introducing the Leslie thermomechanical coupling—only present in chiral mesophases. An explanation based on the Akopyan and Zeldovich theory of thermomechanical effects in nematics is proposed and discussed.

  14. Continuous Rotation of Achiral Nematic Liquid Crystal Droplets Driven by Heat Flux.

    PubMed

    Ignés-Mullol, Jordi; Poy, Guilhem; Oswald, Patrick

    2016-07-29

    Suspended droplets of cholesteric (chiral nematic) liquid crystals spontaneously rotate in the presence of a heat flux due to a temperature gradient, a phenomenon known as the Lehmann effect. So far, it is not clear whether this effect is due to the chirality of the phase and the molecules or only to the chirality of the director field. Here, we report the continuous rotation in a temperature gradient of nematic droplets of a lyotropic chromonic liquid crystal featuring a twisted bipolar configuration. The achiral nature of the molecular components leads to a random handedness of the spontaneous twist, resulting in the coexistence of droplets rotating in the two senses, with speeds proportional to the temperature gradient and inversely proportional to the droplet radius. This result shows that a macroscopic twist of the director field is sufficient to induce a rotation of the droplets, and that the phase and the molecules do not need to be chiral. This suggests that one can also explain the Lehmann rotation in cholesteric liquid crystals without introducing the Leslie thermomechanical coupling-only present in chiral mesophases. An explanation based on the Akopyan and Zeldovich theory of thermomechanical effects in nematics is proposed and discussed. PMID:27517793

  15. Adsorption-induced auto-amplification of enantiomeric excess on an achiral surface

    NASA Astrophysics Data System (ADS)

    Yun, Yongju; Gellman, Andrew J.

    2015-06-01

    The homochirality of biomolecules is a signature of life on Earth and has significant implications in, for example, the production of pharmaceutical compounds. It has been suggested that biomolecular homochirality may have arisen from the amplification of a spontaneously formed small enantiomeric excess (e.e.). Many minerals exhibit naturally chiral surfaces and so adsorption has been proposed as one possible mechanism for such an amplification of e.e. Here we show that when gas-phase mixtures of D- and L-aspartic acid are exposed to an achiral Cu(111) surface, a small e.e. in the gas phase, e.e.g, leads to an amplification of the e.e. on the surface, e.e.s, under equilibrium conditions. Adsorption-induced amplification of e.e. does not require a chiral surface. The dependence of e.e.s on e.e.g has been modelled successfully using a Langmuir-like adsorption isotherm that incorporates the formation of homochiral adsorbate clusters on the surface.

  16. 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. PMID:27136968

  17. Exohedral M-C60 and M2-C60 (M = Pt, Pd) systems as tunable-gap building blocks for nanoarchitecture and nanocatalysis

    NASA Astrophysics Data System (ADS)

    Özdamar, Burak; Boero, Mauro; Massobrio, Carlo; Felder-Flesch, Delphine; Le Roux, Sébastien

    2015-09-01

    Transition metal-fullerenes complexes with metal atoms bound on the external surface of C60 are promising building blocks for next-generation fuel cells and catalysts. Yet, at variance with endohedral M@C60, they have received a limited attention. By resorting to first principles simulations, we elucidate structural and electronic properties for the Pd-C60, Pt-C60, PtPd-C60, Pd2-C60, and Pt2-C60 complexes. The most stable structures feature the metal atom located above a high electron density site, namely, the π bond between two adjacent hexagons (π-66 bond). When two metal atoms are added, the most stable configuration is those in which metal atoms still stand on π-66 bonds but tends to clusterize. The electronic structure, rationalized in terms of localized Wannier functions, provides a clear picture of the underlying interactions responsible for the stability or instability of the complexes, showing a strict relationship between structure and electronic gap.

  18. Triflate-functionalized calix[6]arenes as versatile building-blocks: application to the synthesis of an inherently chiral Zn(ii) complex.

    PubMed

    Zahim, Sara; Lavendomme, Roy; Reinaud, Olivia; Luhmer, Michel; Evano, Gwilherm; Jabin, Ivan

    2016-02-14

    Cavity-based metal complexes can find many applications notably in the fields of catalysis and biomimicry. In this context, it was shown that metal complexes of calix[6]arenes bearing three aza-coordinating arms at the small rim provide excellent structural models of the poly-imidazole sites found in the active site of many metallo-enzymes. All these N-donor ligands were synthesized from the 1,3,5-tris-methoxy-p-tBu-calix[6]arene platform, which presents some limitations in terms of functionalization. Therefore, there is a need for the development of new calix[6]arene-based building-blocks selectively protected at the small rim. Herein we describe the regioselective one step synthesis of two calix[6]arenes decorated with triflate groups, i.e. X6H4Tf2 and X6H3Tf3, from the parent calix[6]arene X6H6. It is shown that the triflate groups can either act as protecting or deactivating groups, allowing the elaboration of sophisticated calixarene-based systems selectively functionalized at the large and/or at the small rim. In addition, X6H3Tf3 is functionalized on the A, B, and D rings and thus gives access to inherently chiral compounds, as demonstrated by the synthesis of a rare example of inherently chiral cavity-based metal complex. PMID:26751614

  19. Molecular assembly of highly symmetric molecules under a hydrogen bond framework controlled by alkyl building blocks: a simple approach to fine-tune nanoscale structures.

    PubMed

    Tanphibal, Pimsai; Tashiro, Kohji; Chirachanchai, Suwabun

    2016-01-14

    To date, molecular assemblies under the contribution of hydrogen bond in combination with weak interactions and their consequent morphologies have been variously reported; however, how the systematic variation of the structure can fine-tune the morphologies has not yet been answered. The present work finds an answer through highly symmetric molecules, i.e. diamine-based benzoxazine dimers. This type of molecule develops unique molecular assemblies with their networks formed by hydrogen bonds at the terminal, while, at the same time, their hydrogen bonded frameworks are further controlled by the hydrophobic segment at the center of the molecule. When this happens, slight differences in hydrophobic alkyl chain lengths (, , and ) bring a significant change to the molecular assemblies, thus resulting in tunable morphologies, i.e. spheres, needles and dendrites. The superimposition between the crystal lattice obtained from X-ray single crystal analysis and the electron diffraction pattern obtained from transmission electron microscopy allows us to identify the molecular alignment from single molecules to self-assembly until the morphologies developed. The present work, for the first time, shows the case of symmetric molecules, where the hydrophobic building block controls the hydrogen bond patterns, leading to the variation of molecular assemblies with tunable morphologies. PMID:26482133

  20. Synthesis of protected enantiopure (R) and (S)-α-trifluoromethylalanine containing dipeptide building blocks ready to use for solid phase peptide synthesis.

    PubMed

    Devillers, Emmanuelle; Pytkowicz, Julien; Chelain, Evelyne; Brigaud, Thierry

    2016-06-01

    Considering the increasing importance of fluorinated peptides, the development of efficient and reliable synthetic methods for the incorporation of unnatural fluorinated amino acids into peptides is a current matter of interest. In this study, we report the convenient Boc/benzyl and Cbz/tert-butyl protection of both enantiomers of the quaternarized amino acid α-trifluoromethylalanine [(R)- and (S)-α-Tfm-Ala]. Because of the deactivation of the nitrogen atom of this synthetic amino acid by the strong electron withdrawing trifluoromethyl group, the peptide coupling on this position is a challenge. In order to provide a robust synthetic methodology for the incorporation of enantiopure (R)- and (S)-α-trifluoromethylalanines into peptides, we report herein the preparation of dipeptides ready to use for solid phase peptide synthesis. The difficult peptide coupling on the nitrogen atom of the α-trifluoromethylalanines was performed in solution phase by means of highly electrophilic amino acid chlorides or mixed anhydrides. The synthetic effectiveness of this fluorinated dipeptide building block strategy is illustrated by the solid phase peptide synthesis (SPPS) of the Ac-Ala-Phe-(R)-α-Tfm-Ala-Ala-NH2 tetrapeptide. PMID:26920748

  1. Aternating current photovoltaic building block

    DOEpatents

    Bower, Ward Issac; Thomas, Michael G.; Ruby, Douglas S.

    2004-06-15

    A modular apparatus for and method of alternating current photovoltaic power generation comprising via a photovoltaic module, generating power in the form of direct current; and converting direct current to alternating current and exporting power via one or more power conversion and transfer units attached to the module, each unit comprising a unitary housing extending a length or width of the module, which housing comprises: contact means for receiving direct current from the module; one or more direct current-to-alternating current inverters; an alternating current bus; and contact means for receiving alternating current from the one or more inverters.

  2. The Building Blocks of Learning

    ERIC Educational Resources Information Center

    Kobrin, Jennifer L.; Panorkou, Nicole

    2016-01-01

    Learning progressions detail the incremental steps that students take as they learn to master a skill. These progressions are based on developmental research about how students learn and how their thinking develops as a result of instruction. A typical progression not only describes the stages that students must master, but it also shows what…

  3. The building blocks of HACCP

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Hazard Analysis and Critical Control Point (HACCP) food safety inspection program is utilized by both USDA Food Safety Inspection Service (FSIS) and FDA for many of the products they regulate. This science-based program was implemented by the USDA FSIS to enhance the food safety of meat and pou...

  4. Biodiversity: Building blocks for crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An increasing global population will require more efficient food production. By year 2025, we will need 20-24% increases in yields of crops to meet the projected increase in food, fiber, and bioenergy demand from the global population. The competition to use limited land and sometimes compromised ...

  5. Chitosan microspheres with an extracellular matrix-mimicking nanofibrous structure as cell-carrier building blocks for bottom-up cartilage tissue engineering

    NASA Astrophysics Data System (ADS)

    Zhou, Yong; Gao, Huai-Ling; Shen, Li-Li; Pan, Zhao; Mao, Li-Bo; Wu, Tao; He, Jia-Cai; Zou, Duo-Hong; Zhang, Zhi-Yuan; Yu, Shu-Hong

    2015-12-01

    Scaffolds for tissue engineering (TE) which closely mimic the physicochemical properties of the natural extracellular matrix (ECM) have been proven to advantageously favor cell attachment, proliferation, migration and new tissue formation. Recently, as a valuable alternative, a bottom-up TE approach utilizing cell-loaded micrometer-scale modular components as building blocks to reconstruct a new tissue in vitro or in vivo has been proved to demonstrate a number of desirable advantages compared with the traditional bulk scaffold based top-down TE approach. Nevertheless, micro-components with an ECM-mimicking nanofibrous structure are still very scarce and highly desirable. Chitosan (CS), an accessible natural polymer, has demonstrated appealing intrinsic properties and promising application potential for TE, especially the cartilage tissue regeneration. According to this background, we report here the fabrication of chitosan microspheres with an ECM-mimicking nanofibrous structure for the first time based on a physical gelation process. By combining this physical fabrication procedure with microfluidic technology, uniform CS microspheres (CMS) with controlled nanofibrous microstructure and tunable sizes can be facilely obtained. Especially, no potentially toxic or denaturizing chemical crosslinking agent was introduced into the products. Notably, in vitro chondrocyte culture tests revealed that enhanced cell attachment and proliferation were realized, and a macroscopic 3D geometrically shaped cartilage-like composite can be easily constructed with the nanofibrous CMS (NCMS) and chondrocytes, which demonstrate significant application potential of NCMS as the bottom-up cell-carrier components for cartilage tissue engineering.Scaffolds for tissue engineering (TE) which closely mimic the physicochemical properties of the natural extracellular matrix (ECM) have been proven to advantageously favor cell attachment, proliferation, migration and new tissue formation

  6. 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

    2014-11-01

    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. PMID:25129794

  7. Time-resolved single-photon detection module based on silicon photomultiplier: A novel building block for time-correlated measurement systems.

    PubMed

    Martinenghi, E; Di Sieno, L; Contini, D; Sanzaro, M; Pifferi, A; Dalla Mora, A

    2016-07-01

    We present the design and preliminary characterization of the first detection module based on Silicon Photomultiplier (SiPM) tailored for single-photon timing applications. The aim of this work is to demonstrate, thanks to the design of a suitable module, the possibility to easily exploit SiPM in many applications as an interesting detector featuring large active area, similarly to photomultipliers tubes, but keeping the advantages of solid state detectors (high quantum efficiency, low cost, compactness, robustness, low bias voltage, and insensitiveness to magnetic field). The module integrates a cooled SiPM with a total photosensitive area of 1 mm(2) together with the suitable avalanche signal read-out circuit, the signal conditioning, the biasing electronics, and a Peltier cooler driver for thermal stabilization. It is able to extract the single-photon timing information with resolution better than 100 ps full-width at half maximum. We verified the effective stabilization in response to external thermal perturbations, thus proving the complete insensitivity of the module to environment temperature variations, which represents a fundamental parameter to profitably use the instrument for real-field applications. We also characterized the single-photon timing resolution, the background noise due to both primary dark count generation and afterpulsing, the single-photon detection efficiency, and the instrument response function shape. The proposed module can become a reliable and cost-effective building block for time-correlated single-photon counting instruments in applications requiring high collection capability of isotropic light and detection efficiency (e.g., fluorescence decay measurements or time-domain diffuse optics systems). PMID:27475542

  8. Al15Ge4Ni3: A new intergrowth structure with Cu3Au- and CaF2-type building blocks

    NASA Astrophysics Data System (ADS)

    Reichmann, Thomas L.; Jandl, Isabella; Effenberger, Herta S.; Herzig, Peter; Richter, Klaus W.

    2015-05-01

    The new ternary compound Al15Ge4Ni3 (τ2 in the system Al-Ge-Ni) was synthesized in single crystalline form by a special annealing procedure from samples located in the three phase fields [L+Al+τ2] and [L+Ge+τ2]. The crystal structure of Al15Ge4Ni3 was determined by single-crystal X-ray diffraction. The compound crystallizes in a new structure type in space group I4¯3m, Pearson Symbol cI88, cubic lattice parameter a=11.405(1) Å. Phase diagram investigations indicate stoichiometric composition without considerable homogeneity range; τ2 melts peritectically at T=444 °C. The crystal structure of Al15Ge4Ni3 shows a unique combination of simple Cu3Au- and CaF2-type building blocks: a three dimensional network of CaF2-type units, formed by Ni and Al atoms, is interspaced by clusters (Al6Ge8) resembling unit cells of the Cu3Au-type. Both structural motifs are connected by Al-Ge bonds. The ground state energy of the compound was obtained by DFT calculations and the densities of states were analyzed in detail. In addition, electron density maps were calculated in four different sections through the unit cell using the full potential linearized augmented plane-wave (FLAPW) method. The bonding situation in Al15Ge4Ni3 was discussed combining results from electronic calculations with the analysis of the coordination of atoms.

  9. 3,3'-Dinitroamino-4,4'-azoxyfurazan and its derivatives: an assembly of diverse N-O building blocks for high-performance energetic materials.

    PubMed

    Zhang, Jiaheng; Shreeve, Jean'ne M

    2014-03-19

    On the basis of a design strategy that results in the assembly of diverse N-O building blocks leading to energetic materials, 3,3'-dinitroamino-4,4'-azoxyfurazan and its nitrogen-rich salts were obtained and fully characterized via spectral and elemental analyses. Oxone (potassium peroxomonosulfate) is an efficient oxidizing agent for introducing the azoxy N-oxide functionality into the furazan backbone, giving a straightforward and low-cost synthetic route. On the basis of heats of formation calculated with Gaussian 03 and combined with experimentally determined densities, energetic properties (detonation velocity, pressure and specific impulse) were obtained using the EXPLO v6.01 program. These new molecules exhibit high density, moderate to good thermal stability, acceptable impact and friction sensitivities, and excellent detonation properties, which suggest potential applications as energetic materials. Interestingly, 3,3'-dinitroamino-4,4'-azoxyfurazan (4) has the highest calculated crystal density of 2.02 g cm(-3) at 173 K (gas pycnometer measured density is 1.96 g cm(-3) at 298 K) for N-oxide energetic compounds yet reported. Another promising compound is the hydroxylammonium salt (6), which has four different kinds of N-O moieties and a detonation performance superior to those of 1,3,5,7-tetranitrotetraazacyclooctane (HMX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclododecane (CL-20). Furthermore, computational results, viz., NBO charges and ESP, also support the superior qualities of the newly prepared compounds and the design strategy. PMID:24571188

  10. Time-resolved single-photon detection module based on silicon photomultiplier: A novel building block for time-correlated measurement systems

    NASA Astrophysics Data System (ADS)

    Martinenghi, E.; Di Sieno, L.; Contini, D.; Sanzaro, M.; Pifferi, A.; Dalla Mora, A.

    2016-07-01

    We present the design and preliminary characterization of the first detection module based on Silicon Photomultiplier (SiPM) tailored for single-photon timing applications. The aim of this work is to demonstrate, thanks to the design of a suitable module, the possibility to easily exploit SiPM in many applications as an interesting detector featuring large active area, similarly to photomultipliers tubes, but keeping the advantages of solid state detectors (high quantum efficiency, low cost, compactness, robustness, low bias voltage, and insensitiveness to magnetic field). The module integrates a cooled SiPM with a total photosensitive area of 1 mm2 together with the suitable avalanche signal read-out circuit, the signal conditioning, the biasing electronics, and a Peltier cooler driver for thermal stabilization. It is able to extract the single-photon timing information with resolution better than 100 ps full-width at half maximum. We verified the effective stabilization in response to external thermal perturbations, thus proving the complete insensitivity of the module to environment temperature variations, which represents a fundamental parameter to profitably use the instrument for real-field applications. We also characterized the single-photon timing resolution, the background noise due to both primary dark count generation and afterpulsing, the single-photon detection efficiency, and the instrument response function shape. The proposed module can become a reliable and cost-effective building block for time-correlated single-photon counting instruments in applications requiring high collection capability of isotropic light and detection efficiency (e.g., fluorescence decay measurements or time-domain diffuse optics systems).

  11. Achiral-chiral two-dimensional chromatography of free amino acids in milk: A promising tool for detecting different levels of mastitis in cows.

    PubMed

    Ianni, Federica; Sardella, Roccaldo; Lisanti, Antonella; Gioiello, Antimo; Cenci Goga, Beniamino Terzo; Lindner, Wolfgang; Natalini, Benedetto

    2015-12-10

    In two-dimensional HPLC (2D-HPLC) "heart-cut" applications, two columns are connected in series via a switching valve and volume fractions from the "primary" column are re-injected on the "secondary" column. The heart-cut 2D-HPLC system here described was implemented by connecting a reversed-phase (RP) column (first dimension) to a chiral column (second dimension) containing a quinidine-based chiral stationary phase. The system was used to evaluate the change in the enantiomeric excess value of dansylated (Dns) amino acids (AAs) in milk samples from two cows with different "California Mastitis Test" scores: negative test for sample 1, positive for sample 2. Apart from the co-elution of Dns-Arg/Dns-Gly and the reduced chemoselectivity for Dns-Leu/Dns-allo-Ile, the optimized achiral RP method distinguished the remaining standard Dns-AAs. Dns-AAs were identified in the chromatograms of the real samples, and in higher concentration Dns-Ala, Dns-Arg, Dns-Asp, Dns-Glu, Dns-Ile, Dns-Leu, Dns-Phe and Dns-Val. Except Dns-Arg, the chiral column enabled the RP enantioseparation of all the other compounds (α and RS values up to 1.65 and 8.63, respectively, for Dns-Phe). In sample 2, the amounts of Dns-d-AAs were rather elevated, in particular for Dns-Ala and Dns-Asp. Instead, for sample 1, D-isomers were detected for Dns-Ala, Dns-Glu and Dns-Leu. The proposed 2D-HPLC method could be useful for the identification of clinical mastitis difficult to be diagnosed. Moreover, the eventual progressive reduction of D-AAs levels with the degree of sub-clinical mastitis could allow the building of mathematical models to use for the diagnosis of early stages of mastitis. PMID:25617178

  12. From linking of metal-oxide building blocks in a dynamic library to giant clusters with unique properties and towards adaptive chemistry.

    PubMed

    Müller, Achim; Gouzerh, Pierre

    2012-11-21

    Following Nature's lessons, today chemists can cross the boundary of the small molecule world to construct multifunctional and highly complex molecular nano-objects up to protein size and even cell-like nanosystems showing responsive sensing. Impressive examples emerge from studies of the solutions of some oxoanions of the early transition metals especially under reducing conditions which enable the controlled linking of metal-oxide building blocks. The latter are available from constitutional dynamic libraries, thus providing the option to generate multifunctional unique nanoscale molecular systems with exquisite architectures, which even opens the way towards adaptive and evolutive (Darwinian) chemistry. The present review presents the first comprehensive report of current knowledge (including synthesis aspects not discussed before) regarding the related giant metal-oxide clusters mainly of the type {Mo(57)M'(6)} (M' = Fe(III), V(IV)) (torus structure), {M(72)M'(30)} (M = Mo, M' = V(IV), Cr(III), Fe(III), Mo(V)), {M(72)Mo(60)} (M = Mo, W) (Keplerates), {Mo(154)}, {Mo(176)}, {Mo(248)} ("big wheels"), and {Mo(368)} ("blue lemon") - all having the important transferable pentagonal {(M)M(5)} groups in common. These discoveries expanded the frontiers of inorganic chemistry to the mesoscopic world, while there is probably no collection of discrete inorganic compounds which offers such a versatile chemistry and the option to study new phenomena of interdisciplinary interest. The variety of different properties of the sphere- and wheel-type metal-oxide-based clusters can directly be related to their unique architectures: The spherical Keplerate-type capsules having 20 crown-ether-type pores and tunable internal functionalities allow the investigation of confined matter as well as that of sphere-surface-supramolecular and encapsulation chemistry - including related new aspects of the biologically important hydrophobic effects - but also of nanoscale ion transport and

  13. STELLAR POPULATIONS OF Ly{alpha} EMITTERS AT z {approx} 6-7: CONSTRAINTS ON THE ESCAPE FRACTION OF IONIZING PHOTONS FROM GALAXY BUILDING BLOCKS

    SciTech Connect

    Ono, Yoshiaki; Shimasaku, Kazuhiro; Okamura, Sadanori; Masami Ouchi; Dunlop, James; Farrah, Duncan; McLure, Ross

    2010-12-01

    We investigate the stellar populations of Ly{alpha} emitters (LAEs) at z = 5.7 and 6.6 in a 0.65 deg{sup 2} sky of the Subaru/XMM-Newton Deep Survey (SXDS) Field, using deep images taken with the Subaru/Suprime-Cam, United Kingdom Infrared Telescope/Wide Field Infrared Camera, and Spitzer/Infrared Array Camera (IRAC). We produce stacked multiband images at each redshift from 165 (z = 5.7) and 91 (z = 6.6) IRAC-undetected objects to derive typical spectral energy distributions (SEDs) of z {approx} 6-7 LAEs for the first time. The stacked LAEs have as blue UV continua as the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) z-dropout galaxies of similar M{sub UV}, with a spectral slope {beta} {approx} -3, but at the same time they have red UV-to-optical colors with detection in the 3.6 {mu}m band. Using SED fitting we find that the stacked LAEs have low stellar masses of {approx}(3-10) x 10{sup 7} M{sub sun}, very young ages of {approx}1-3 Myr, negligible dust extinction, and strong nebular emission from the ionized interstellar medium, although the z = 6.6 object is fitted similarly well with high-mass models without nebular emission; inclusion of nebular emission reproduces the red UV-to-optical colors while keeping the UV colors sufficiently blue. We infer that typical LAEs at z {approx} 6-7 are building blocks of galaxies seen at lower redshifts. We find a tentative decrease in the Ly{alpha} escape fraction from z = 5.7 to 6.6, which may imply an increase in the intergalactic medium neutral fraction. From the minimum contribution of nebular emission required to fit the observed SEDs, we place an upper limit on the escape fraction of ionizing photons of f {sup ion}{sub esc} {approx} 0.6 at z = 5.7 and {approx}0.9 at z = 6.6. We also compare the stellar populations of our LAEs with those of stacked HST/WFC3 z-dropout galaxies.

  14. A review on the spontaneous formation of the building blocks of life and the generation of a set of hypotheses governing universal abiogenesis

    NASA Astrophysics Data System (ADS)

    Palmer, B. S.

    2013-01-01

    There have been a number of hypotheses regarding abiogenesis, the `Metabolism First' model and the `RNA World Hypothesis' are two such examples. All theories on abiogenesis make a set of unstated assumptions with regard to the elemental make up of life or only apply the theory to a primitive earth model. This paper reviews current knowledge from the myriad of observations from a variety of scientific disciplines and applies generally understood thermodynamic reasoning to explain the formation of molecules known to be used by life. These arguments are used in this paper to construct a set of new hypotheses which govern universal abiogenesis. The intention of this paper is to show by the application of our known laws of science that life is the end sequence of events of the fundamental forces which affect the entire universe. From these events a new hypotheses on abiogenesis can be formulated. The hypotheses proposed by this paper are incorporated in many of the current theories of abiogenesis, either assumed or accepted but very rarely stated or explained. The proposed set of five hypotheses are: (1) any celestial mass that has a body of liquid water and therefore has access to energy will form at least the building blocks of life, if not life itself. (2) The major component of any life form anywhere in the universe will be H2O. (3) Any organism, anywhere in the universe, will be carbon-based. (4) All life in the universe will be composed of nucleic acid based molecules as its code for life. (5) The cell is the universal unit of life. Throughout this paper the background to the formulation of these hypotheses is discussed, as is the explanation of why these hypotheses are universal and not limited to an application of a primitive earth model. This set of hypotheses is also testable as any investigation of a celestial body which contains liquid water (e.g. Europa) will quickly provide evidence to prove or refute the proposed theory.

  15. Hierarchical assembly of an achiral pi-conjugated molecule into a chiral nanotube through the air/water interface.

    PubMed

    Yao, Pingping; Wang, Haifeng; Chen, Penglei; Zhan, Xiaowei; Kuang, Xun; Zhu, Daoben; Liu, Minghua

    2009-06-16

    An achiral pi-conjugated fluorinated fused pyrazine derivative has been spread at the air/water interface, and its assembling property is investigated. It has been found that the compound, although without any long alkyl chain, could be spread as a floating film on water surface, the surface pressure of which can be compressed up to ca. 70 mN/m. An inflection point has been observed in the isotherm of the floating film on water surface. The atomic force microscope (AFM), scanning electron microscope (SEM) as well as the transmission electron microscope (TEM) observations revealed that the floating film first formed a multilayer structure and then was compressed into nanotubes after the inflection region as a result of the rolling of the ultrathin film. Interestingly, the rolled nanotubes show circular dichroism although the molecule itself is an achiral species, suggesting the chiral nanotube is predominantly produced on the water surface. The investigation provides an effective way to fabricate supramolecular-based organic chiral nanotubes through an interfacial supramolecular assembly process. PMID:19459675

  16. Planar anchoring strength and pitch measurements in achiral and chiral chromonic liquid crystals using 90-degree twist cells.

    PubMed

    McGinn, Christine K; Laderman, Laura I; Zimmermann, Natalie; Kitzerow, Heinz-S; Collings, Peter J

    2013-12-01

    Chromonic liquid crystals are formed by molecules that spontaneously assemble into anisotropic structures in water. The ordering unit is therefore a molecular assembly instead of a molecule as in thermotropic liquid crystals. Although it has been known for a long time that certain dyes, drugs, and nucleic acids form chromonic liquid crystals, only recently has enough knowledge been gained on how to control their alignment so that studies of their fundamental liquid crystal properties can be performed. In this article, a simple method for producing planar alignment of the nematic phase in chromonic liquid crystals is described, and this in turn is used to create twisted nematic structures of both achiral and chiral chromonic liquid crystals. The optics of 90-degree twist cells allows the anchoring strength to be measured in achiral systems, which for this alignment technique is quite weak, about 3×10(-7) J/m(2) for both disodium cromoglycate and Sunset Yellow FCF. The addition of a chiral amino acid to the system causes the chiral nematic phase to form, and similar optical measurements in 90-degree twist cells produce a measurement of the intrinsic pitch of the chiral nematic phase. From these measurements, the helical twisting power for L-alanine is found to be (1.1±0.4)×10(-2) μm(-1) wt%(-1) for 15 wt% disodium cromoglycate. PMID:24483474

  17. Comparison of positively and negatively charged achiral co-monomers added to cyclodextrin monolith: improved chiral separations in capillary electrochromatography.

    PubMed

    Lu, Yang; Shamsi, Shahab A

    2014-10-01

    Cyclodextrins (CDs) and their derivatives have been one of the most popular and successful chiral additives used in electrokinetic chromatography because of the presence of multiple chiral centers, which leads to multiple chiral interactions. However, there has been relatively less published work on the use of CDs as monolithic media for capillary electrochromatography (CEC). The goal of this study was to show how the addition of achiral co-monomer to a polymerizable CD such as glycidyl methacrylate β-cyclodextrin (GMA/β-CD) can affect the enantioselective separations in monolithic CEC. To achieve this goal, polymeric monoliths columns were prepared by co-polymerizing GMA/β-CD with cationic or anionic achiral co-monomers [(2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and vinyl benzyltrimethyl-ammonium (VBTA)] in the presence of conventional crosslinker (ethylene dimethacrylate) and ternary porogen system including butanediol, propanol and water. A total of 34 negatively charged compounds, 30 positively charged compounds and 33 neutral compounds were screened to compare the enantioresolution capability on the GMA/β-CD, GMA/β-CD-VBTA and GMA/β-CD-AMPS monolithic columns. PMID:24108813

  18. Chirality in block copolymer melts: mesoscopic helicity from intersegment twist.

    PubMed

    Zhao, Wei; Russell, Thomas P; Grason, Gregory M

    2013-02-01

    We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self-consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesoscopically chiral phases are stable: an undulated lamellar phase and a phase of hexagonally ordered helices. We show that the nonlinear sensitivity of mesoscale chiral order to preferred pitch derives specifically from the geometric and thermodynamic coupling of the helical mesodomain shape to the twisted packing of chiral segments within the core, giving rise to a second-order cylinder-to-helix transition. PMID:23414052

  19. Population Blocks.

    ERIC Educational Resources Information Center

    Smith, Martin H.

    1992-01-01

    Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

  20. Self-Assembly of Reactive Linear Cu3 Building Blocks for Supramolecular Coordination Chemistry and Their Reactivity toward E(n) Ligand Complexes.

    PubMed

    Fleischmann, Martin; Dütsch, Luis; Elsayed Moussa, Mehdi; Balázs, Gábor; Kremer, Werner; Lescop, Christophe; Scheer, Manfred

    2016-03-21

    This study describes the selective synthesis of linear, trinuclear, halide-bridged Cu(I) complexes [Cu3(μ-X)2(μ-dpmp)2(MeCN)2](+) (1a: X = Cl; 1b: X = Br; 1c: X = I) stabilized by the tridentate dpmp ligand obtained by self-assembly reactions in THF/MeCN. Upon drying, the MeCN ligands can be removed and the complexes are transformed to the reactive parent trinuclear [Cu3(μ-X)2(μ-dpmp)2](+) (2a-c) building blocks with two vacant coordination sites on the terminal Cu atoms. Another synthesis in CH2Cl2 directly yields 2a-c. Additionally, two related isomeric compounds, 2a* and 2c*, and two CH2Cl2-ligated complexes, [Cu3(μ-X)2(μ-dpmp)2(CH2Cl2)2](+) (X = Br (3b), I (3c)), were structurally characterized. The frameworks of the cationic [Cu3(μ-X)2(μ-dpmp)2](+) complexes are stable in solution at low temperatures and show dynamic coordination behavior at elevated temperatures, indicated by new signals arising in the (31)P{(1)H} NMR spectra. This evolution cannot be shifted back by decreasing the temperature again. However, cationic [Cu3(μ-X)2(μ-dpmp)2](+) (X = Cl, Br, I) complexes can be obtained selectively in the solid state upon crystallization. Although reactions of 2a-c with complexes [{CpMo(CO)2}2(μ,η(2):η(2)-E2)] (E = P (A1), As (A2)) led to unsymmetrically substituted [Cu3(μ-X)2(μ-dpmp)2(η(1)-L)](+) (4a-c: X = Cl-I, L = A1; 5: X = Cl, L = A2) complexes, reactions with the cyclo-P3 complex [CpMo(CO)2(η(3)-P3)] (B) afforded zigzag chain polymers [Cu3(μ-X)2(μ-dpmp)2(μ,η(1):η(1)-B)]n[BF4]n (6a: X = Cl; 6b: X = Br) and symmetrically substituted complex [Cu3(μ-I)2(μ-dpmp)2(η(1)-B)2](+) (7). Reactions of 2a-c with cyclo-E5 complexes [Cp*Fe(η(5)-E5)] (E = P (C1), As (C2)) led to the isolation of one-dimensional coordination polymers [Cu3(μ-X)2(μ-dpmp)2(μ,η(1):η(1)-L)]n[BF4]n (8a-b: X = Cl-Br, L = C1; 9: X = Cl, L = C2) and symmetrically substituted complex [Cu3(μ-I)2(μ-dpmp)2(η(1)-C1)2](+) (10). All products exhibit a trinuclear, cationic

  1. Determinations of PCB within a project to develop cleanup methods for PCB-containing elastic sealant used in outdoor joints between concrete blocks in buildings.

    PubMed

    Sundahl, M; Sikander, E; Ek-Olausson, B; Hjorthage, A; Rosell, L; Tornevall, M

    1999-08-01

    Determinations of PCB were carried out as part of a project aimed at developing cleanup methods for PCB-containing elastic sealant used in outdoor joints between concrete blocks. The goals of the project were to develop methods, which minimise the spread of PCB to the outdoor environment and to indoor air, and which keep the PCB levels as low as reasonably possible in the workplace environment whilst removing the elastic sealant. The following PCB determinations were carried out: (1) concentration in the elastic sealant; (2) concentration in the concrete close to the sealant; (3) concentration in soil; (4) concentration in the indoor air; and (5) concentration in the air in the workplace environment. The cleanup process consisted of a number of different steps: (1) cutting the elastic sealant with an oscillating knife; (2) grinding the concrete with a mechanical machine; (3) sawing the concrete with a mechanical saw and (4) cutting the concrete with a mechanical chisel. In all these different steps a high capacity vacuum cleaner connected to the machines was used. The elastic sealant contained 4.7 to 8.1% total PCB of a technical product with a composition most similar to Clophene A40. The concrete close to the sealant (first 2 mm) contained 0.12 and 1.7% total PCB at two different places. The pattern of the PCB in the concrete resembled that of the sealant. PCB concentrations in the soil from the ground close to the building were 0.1 and 0.3 ppm at two different places before the remedial action. The source of the PCB in the soil is most likely the sealant as the PCB pattern is similar for the two materials. The PCB levels in the workplace air at the beginning of the project, when the techniques were not fully developed, were generally above the occupational exposure limit of 10 micrograms m-3 (up to 120 micrograms m-3). Later when the techniques were optimised to better take care of dust and gases produced during the cutting and grinding etc., the levels were

  2. Synthesis and mesomorphic behaviour of achiral four-ring unsymmetrical bent-core liquid crystals: Nematic phases

    NASA Astrophysics Data System (ADS)

    Paul, Manoj Kumar; Kalita, Gayatri; Laskar, Atiqur Rahman; Debnath, Somen; Gude, Venkatesh; Sarkar, Dipika Debnath; Mohiuddin, Golam; Varshney, Sanjay Kumar; Nandiraju Rao, V. S.

    2013-10-01

    Achiral four ring unsymmetrical bent-core liquid crystals derived from 3-amino-2-methylbenzoic acid have been designed and synthesized with an imine, ester and photochromic azo linking moieties. These hockey-stick shape resembling bent molecules possess an alkoxy chain at one end of the molecule and methyl or methoxy group at the other end. The synthesis, phase transition temperatures and characterization of phase behaviour are discussed. The molecular structure characterization is consistent with data from elemental and spectroscopic analysis. The materials thermal behaviour and phase characterization have been investigated by differential scanning calorimetry and polarizing optical microscopy. All these compounds exhibit enantiotropic nematic phase over wide temperature range. Stable supercooling of nematic phase has been observed in methoxy homologues. The density functional theory (DFT) calculations were performed to obtain the stable molecular conformation, polarizability, dipole moment, Highest occupied molecular orbital (HOMO), Lowest unoccupied molecular orbital (LUMO) energies and bending angle of the compound.

  3. Twist-bend heliconical chiral nematic liquid crystal phase of an achiral rigid bent-core mesogen

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Nakata, Michi; Shao, Renfan; Tuchband, Michael R.; Shuai, Min; Baumeister, Ute; Weissflog, Wolfgang; Walba, David M.; Glaser, Matthew A.; Maclennan, Joseph E.; Clark, Noel A.

    2014-02-01

    The chiral, heliconical (twist-bend) nematic ground state is reported in an achiral, rigid, bent-core mesogen (UD68). Similar to the nematic twist-bend (NTB) phase observed in bent molecular dimers, the NTB phase of UD68 forms macroscopic, smecticlike focal-conic textures and exhibits nanoscale, periodic modulation with no associated modulation of the electron density, i.e., without a detectable lamellar x-ray reflection peak. The NTB helical pitch is pTB˜14 nm. When an electric field is applied normal to the helix axis, a weak electroclinic effect is observed, revealing 50-μm-scale left- and right-handed domains in a chiral conglomerate.

  4. Crystal transformation synthesis of a highly stable fluorescent 3D indium-tetranuclear {In4(μ2-OH)3} building block based metal organic framework through a dinuclear complex.

    PubMed

    Wang, Xin-Ming; Fan, Rui-Qing; Qiang, Liang-Sheng; Wang, Ping; Yang, Yu-Lin; Wang, Yu-Lei

    2014-11-21

    A rare 3D tetranuclear {In4(μ2-OH)3} building block based MOF {[In4/3(μ2-OH)(2,6-pydc)(1,4-bda)0.5(H2O)]·2H2O}n (2) was obtained through a crystal transformation from a dimeric complex In3(2,6-pydc)3(1,4-bda)1.5(H2O)6 (1). With a 2D + 3D → 3D compact structure, 2 retains crystallinity in boiling water and organic solvents, exhibiting exceptional fluorescence quenching behaviour for the DMSO molecule. PMID:25135576

  5. Tailored Assemblies of Rod-Coil Poly(3-hexylthiophene)-b-Polystyrene Diblock Copolymers: Adaptable Building Blocks for High-Performance Organic Field-Effect Transistors

    SciTech Connect

    Xiao, Kai; Yu, Xiang; Chen, Jihua; Lavrik, Nickolay V; Hong, Kunlun; Sumpter, Bobby; Geohegan, David B

    2011-01-01

    The self-assembly process and resulting structure of a series of conductive diblock copolymer thin films of Poly(3-hexylthiophene)-b-Polystyrene (P3HT-b-PS) have been studied by TEM, SAED, GIXD and AFM and additionally by first principles modeling and simulation. By varying the molecular weight of the P3HT segment, these block copolymers undergo microphase separation and self-assemble into nanostructured sphere, lamellae, nanofiber, and nanoribbon in the films. Within the diblock copolymer thin film, the convalently bonded PS blocks segregated to form amorphous domains, however, the conductive P3HT blocks were crystalline, exhibiting highly-ordered molecular packing with their alkyl side chains aligned along to the normal to the substrate and the - stacking direction of the thiophene rings aligned parallel to the substrate. The conductive P3HY block copolymers exhibited significant improvements in organic feild-effect transistor (OFET) performance and environmental stability as compared to P3HT homopolymers, with up to a factor of two increase in measured moblity (0.08 cm2/Vs ) for the P4 (85 wt% P3HT). Overall, this work demonstrates that the high degree of molecular order induced by bock copolymer phase separation can improve the transport properties and stability of conductive polymer critical for high-performance OFET s.

  6. Ionic Blocks

    ERIC Educational Resources Information Center

    Sevcik, Richard S.; Gamble, Rex; Martinez, Elizabet; Schultz, Linda D.; Alexander, Susan V.

    2008-01-01

    "Ionic Blocks" is a teaching tool designed to help middle school students visualize the concepts of ions, ionic compounds, and stoichiometry. It can also assist high school students in reviewing their subject mastery. Three dimensional blocks are used to represent cations and anions, with color indicating charge (positive or negative) and size…

  7. Gaussian curvature analysis allows for automatic block placement in multi-block hexahedral meshing.

    PubMed

    Ramme, Austin J; Shivanna, Kiran H; Magnotta, Vincent A; Grosland, Nicole M

    2011-10-01

    Musculoskeletal finite element analysis (FEA) has been essential to research in orthopaedic biomechanics. The generation of a volumetric mesh is often the most challenging step in a FEA. Hexahedral meshing tools that are based on a multi-block approach rely on the manual placement of building blocks for their mesh generation scheme. We hypothesise that Gaussian curvature analysis could be used to automatically develop a building block structure for multi-block hexahedral mesh generation. The Automated Building Block Algorithm incorporates principles from differential geometry, combinatorics, statistical analysis and computer science to automatically generate a building block structure to represent a given surface without prior information. We have applied this algorithm to 29 bones of varying geometries and successfully generated a usable mesh in all cases. This work represents a significant advancement in automating the definition of building blocks. PMID:20924860

  8. Characterization of a chiral phase in an achiral bent-core liquid crystal by polarization studies of resonant x-ray forbidden reflections

    NASA Astrophysics Data System (ADS)

    Ponsinet, V.; Barois, P.; Pan, Lidong; Wang, Shun; Huang, C. C.; Wang, S. T.; Pindak, R.; Baumeister, U.; Weissflog, W.

    2011-07-01

    The chiral antiferroelectric structure of an achiral bent-core liquid crystal is characterized by resonant x-ray scattering at chlorine K edge. The “forbidden” reflections resulting from the glide or screw symmetry elements are restored by the anisotropy of the tensor structure factor, which we calculate for two possible structural models. A careful analysis of the polarization states of the restored “forbidden” reflections enables an unambiguous identification of a chiral structure (i.e., the so-called anticlinic, antiferroelectric smectic-C or Sm-CAPA) coexisting with the achiral synclinic antiferroelectric smectic-C or Sm-CSPA. The method proves to be quite powerful as it identifies the chiral structure within coexisting phases despite an imperfect orientation of the sample. The volume fraction of the chiral phase and the distribution of alignment are extracted from the data.

  9. Characterization of a chiral phase in an achiral bent-core liquid crystal by polarization studies of resonant x-ray forbidden reflections

    SciTech Connect

    Ponsinet, V.; Pindak, R.; Barois, P.; Pan, L.; Wang, S.; Huang, C.C.; Wang, S.T.; Baumeister, U. and Weissflog, W.

    2011-07-15

    The chiral antiferroelectric structure of an achiral bent-core liquid crystal is characterized by resonant x-ray scattering at chlorine K edge. The 'forbidden' reflections resulting from the glide or screw symmetry elements are restored by the anisotropy of the tensor structure factor, which we calculate for two possible structural models. A careful analysis of the polarization states of the restored 'forbidden' reflections enables an unambiguous identification of a chiral structure (i.e., the so-called anticlinic, antiferroelectric smectic-C or Sm-C{sub A}P{sub A}) coexisting with the achiral synclinic antiferroelectric smectic-C or Sm-C{sub S}P{sub A}. The method proves to be quite powerful as it identifies the chiral structure within coexisting phases despite an imperfect orientation of the sample. The volume fraction of the chiral phase and the distribution of alignment are extracted from the data.

  10. Building Numbers from Primes

    ERIC Educational Resources Information Center

    Burkhart, Jerry

    2009-01-01

    Prime numbers are often described as the "building blocks" of natural numbers. This article shows how the author and his students took this idea literally by using prime factorizations to build numbers with blocks. In this activity, students explore many concepts of number theory, including the relationship between greatest common factors and…

  11. Helical Self-Assembly and Photopolymerization Properties of Achiral Amphiphilic Platinum(II) Diacetylene Complexes of Tridentate 2,6-Bis(1-alkylpyrazol-3-yl)pyridines.

    PubMed

    Li, Yongguang; Wong, Keith Man-Chung; Wong, Hok-Lai; Yam, Vivian Wing-Wah

    2016-07-13

    Amphiphilic platinum(II) diacetylene complexes of the 2,6-bis(1-butylpyrazol-3-yl)pyridine pincer ligand were designed and synthesized. Helical fibrous nanostructures were obtained through supramolecular assembly of the achiral platinum(II) diacetylene complexes via intermolecular hydrogen bonding, amphiphilic effects, Pt···Pt interactions, and π-π stacking interactions. In situ post-photopolymerization of the diacetylene unit was shown to occur in the preorganized helical fibers. PMID:27348758

  12. Achiral CdSe quantum dots exhibit optical activity in the visible region upon post-synthetic ligand exchange with D- or L-cysteine.

    PubMed

    Tohgha, Urice; Varga, Krisztina; Balaz, Milan

    2013-03-01

    Semiconductor cadmium selenide (CdSe) quantum dots (QDs) exhibited mirror-image circular dichroism (CD) spectra in the visible region (350-570 nm) after replacing the trioctylphosphine oxide/oleic acid ligands on achiral nanocrystals with D- and L-cysteines. Chiroptical properties of cysteine-capped CdSe QDs depend on their size and can be fine-tuned by changing the radius of QDs. PMID:23361413

  13. Block Play: Practical Suggestions for Common Dilemmas

    ERIC Educational Resources Information Center

    Tunks, Karyn Wellhousen

    2009-01-01

    Learning materials and teaching methods used in early childhood classrooms have fluctuated greatly over the past century. However, one learning tool has stood the test of time: Wood building blocks, often called unit blocks, continue to be a source of pleasure and learning for young children at play. Wood blocks have the unique capacity to engage…

  14. Al{sub 15}Ge{sub 4}Ni{sub 3}: A new intergrowth structure with Cu{sub 3}Au- and CaF{sub 2}-type building blocks

    SciTech Connect

    Reichmann, Thomas L.; Jandl, Isabella; Effenberger, Herta S.; Herzig, Peter; Richter, Klaus W.

    2015-05-15

    The new ternary compound Al{sub 15}Ge{sub 4}Ni{sub 3} (τ{sub 2} in the system Al–Ge–Ni) was synthesized in single crystalline form by a special annealing procedure from samples located in the three phase fields [L+Al+τ{sub 2}] and [L+Ge+τ{sub 2}]. The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} was determined by single-crystal X-ray diffraction. The compound crystallizes in a new structure type in space group I4-bar3m, Pearson Symbol cI88, cubic lattice parameter a=11.405(1) Å. Phase diagram investigations indicate stoichiometric composition without considerable homogeneity range; τ{sub 2} melts peritectically at T=444 °C. The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} shows a unique combination of simple Cu{sub 3}Au- and CaF{sub 2}-type building blocks: a three dimensional network of CaF{sub 2}-type units, formed by Ni and Al atoms, is interspaced by clusters (Al{sub 6}Ge{sub 8}) resembling unit cells of the Cu{sub 3}Au-type. Both structural motifs are connected by Al–Ge bonds. The ground state energy of the compound was obtained by DFT calculations and the densities of states were analyzed in detail. In addition, electron density maps were calculated in four different sections through the unit cell using the full potential linearized augmented plane-wave (FLAPW) method. The bonding situation in Al{sub 15}Ge{sub 4}Ni{sub 3} was discussed combining results from electronic calculations with the analysis of the coordination of atoms. - Graphical abstract: The new compound Al{sub 15}Ge{sub 4}Ni{sub 3} shows a unique combination of simple Cu{sub 3}Au- and CaF{sub 2}-type building blocks. - Highlights: • The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} (space group I4-bar3m) was determined. • It shows a unique combination of CaF{sub 2}- and Cu{sub 3}Au-type building blocks. • Electronic (DFT) calculations were performed to gain insight to chemical bonding.

  15. Multi-step control over self-assembled hydrogels of peptide-derived building blocks and a polymeric cross-linker.

    PubMed

    Nguyen, Van Duc; Pal, Asish; Snijkers, Frank; Colomb-Delsuc, Mathieu; Leonetti, Giulia; Otto, Sijbren; van der Gucht, Jasper

    2016-01-14

    We present a detailed study of self-assembled hydrogels of bundled and cross-linked networks consisting of positively charged amyloid-like nanofibers and a triblock copolymer with negatively charged end blocks as a cross-linker. In a first step small oligopeptides self-assemble into macrocycles which are held together by reversible disulfide bonds. Interactions between the peptides cause the macrocycles to assemble into nanofibers, which form a reversible hydrogel. The physical properties of the hydrogel are tuned using various methods such as control over the fibre length, addition of a cross-linking copolymer, and addition of salt. We establish a relationship between the bulk mechanical properties, the properties of the individual fibers and the hydrogel morphology using characterization techniques operating at different length scales such as rheology, atomic force microscopy (AFM) and cryo transmission electron microscopy (Cryo-TEM). This allows for a precise control of the elastic behaviour of these networks. PMID:26477580

  16. The Quest for Modular Nanocages: tbo-MOF as an Archetype for Mutual Substitution, Functionalization, and Expansion of Quadrangular Pillar Building Blocks

    SciTech Connect

    Eubank, Jarrod F.; Mouttaki, Hasnaa; Cairns, Amy J.; Belmabkhout, Youssef; Wojtas, Lukasz; Luebke, Ryan; Alkordi, Mohamed; Eddaoudi, Mohamed

    2011-12-09

    A new blueprint network for the design and synthesis of porous, functional 3D metal-organic frameworks (MOFs) has been identified, namely, the tbo net. Accordingly, tbo-MOFs based on this unique (3,4)-connected net can be exclusively constructed utilizing a combination of well-known and readily targeted [M(R-BDC)]{sub n} MOF layers [i.e., supermolecular building layers (SBLs)] based on the edge-transitive 4,4 square lattice (sql) (i.e., 2D four-building units) and a novel pillaring strategy based on four proximal isophthalate ligands from neighboring SBL membered rings (i.e., two pairs from each layer) covalently cross-linked through an organic quadrangular core (e.g., tetrasubstituted benzene). Our strategy permits the rational design and synthesis of isoreticular structures, functionalized and/or expanded, that possess extra-large nanocapsule-like cages, high porosity, and potential for gas separation and storage, among others. Thus, tbo-MOF serves as an archetypal tunable, isoreticular MOF platform for targeting desired applications.

  17. Versatility of the ionic assembling method to design highly luminescent PMMA nanocomposites containing [M6Q(i)8L(a)6](n-) octahedral nano-building blocks.

    PubMed

    Amela-Cortes, Maria; Molard, Yann; Paofai, Serge; Desert, Anthony; Duvail, Jean-Luc; Naumov, Nikolay G; Cordier, Stéphane

    2016-01-01

    New luminescent poly(methylmethacrylate) (PMMA) nanocomposites with high content of different hexanuclear octahedral cluster building blocks, namely [Mo6I8(C2F5COO6)](2-), [Re6Se8(CN)6](4-) and [W6Cl14](2-) have been prepared by free-radical polymerisation. To do so, cluster complexes bearing a polymerisable ammonium counter-cation have been synthesised. In this way, we demonstrate that ionic assembling is a powerful tool to functionalise easily any type of anionic cluster units to be introduced in a PMMA organic matrix. All samples remain homogeneous, stable during several months, and retain the luminescence properties of the cluster precursor. PMID:26599524

  18. A novel class of achiral seco-analogs of CC-1065 and the duocarmycins: design, synthesis, DNA binding, and anticancer properties.

    PubMed

    Kupchinsky, Stanley; Centioni, Sara; Howard, Tiffany; Trzupek, John; Roller, Shane; Carnahan, Virginia; Townes, Heather; Purnell, Bethany; Price, Carly; Handl, Heather; Summerville, Kaitlin; Johnson, Kimberly; Toth, James; Hudson, Stephen; Kiakos, Konstantinos; Hartley, John A; Lee, Moses

    2004-12-01

    The synthesis, DNA binding properties, and in vitro and in vivo anticancer activity of fifteen achiral seco-cyclopropylindoline (or achiral seco-CI) analogs (5a-o) of CC-1065 and the duocarmycins are described. The achiral seco-CI analogs contain a 4-hydroxyphenethyl halide moiety that is attached to a wide range of indole, benzimidazole, pyrrole, and pyridyl-containing noncovalent binding components. The 4-hydroxyphenethyl halide moiety represents the simplest mimic of the seco-cyclopropylpyrroloindoline (seco-CPI) pharmacophore found in the natural products, and it lacks a chiral center. The sequence and minor groove specificity of the achiral compounds was ascertained using a Taq DNA polymerase stop assay and a thermal induced DNA cleavage experiment using either a fragment of pBR322 or pUC18 plasmid DNA. For example, seco-CI-InBf (5a) and seco-CI-TMI (5c) demonstrated specificity for AT-rich sequences, particularly by reacting with the underlined adenine-N3 position of 5'-AAAAA(865)-3'. This is also the sequence that CC-1065 and adozelesin prefer to alkylate. The achiral seco-CI compounds were subjected to cytotoxicity studies against several human (K562, LS174T, PC3, and MCF-7) and murine cancer cell lines (L1210 and P815). Following continuous drug exposure, the achiral compounds were found to be cytotoxic, with IC(50) values in the muM range. Interestingly, the carbamate protected compound 5p was significantly less cytotoxic than agent 5c, supporting the hypothesis that loss of HCl and formation of a spiro[2,5]cyclopropylcyclohexadienone intermediate is necessary for biological activity. The achiral seco-CI compounds 5a and 5c were submitted to the National Cancer Institute for further cytotoxicity screening against a panel of 60 different human cancer cell lines. Both compounds showed significant activity, particularly against several solid tumor cell lines. Flow cytometry studies of P815 cells that were incubated with compound 5c at its IC(50

  19. Smoothing of geoelectrical resistivity profiles in order to build a 3D model: A case study from an outcropping limestone block

    NASA Astrophysics Data System (ADS)

    Tóth, Krisztina; Kovács, Gábor

    2014-05-01

    Geoelectrical imaging is one of the most common survey methods in the field of shallow geophysics. In order to get information from the subsurface electric current is induced into the ground. In our summer camp organized by the Department of Geophysics and Space Sciences, Eötvös Loránd University we have carried out resistivity surveys to get more accurate information about the lithology of the Dorog basin located in the Transdanubian range, Middle Hungary. This study focused on the outcropping limestone block located next to the village Leányvár in the Dorog basin. The main aim of the research is the impoundment of the subsurface continuation of the limestone outcrop. Cable problems occurred during field survey therefore the dataset obtained by the measurement have become very noisy thus we had to gain smoothed data with the appropriate editing steps. The goal was to produce an optimized model to demonstrate the reality beneath the subsurface. In order to achieve better results from the noisy dataset we changed some parameters based on the description of the program. Whereas cable problems occurred we exterminated the bad datum points visually and statistically as well. Because of the noisiness we increased the value of the so called damping factor which is a variable parameter in the equation used by the inversion routine responsible for smoothing the data. The limitation of the range of model resistivity values based on our knowledge about geological environment was also necessary in order to avoid physically unrealistic results. The purpose of the modification was to obtain smoothed and more interpretable geoelectric profiles. The geological background combined with the explanation of the profiles gave us the approximate location of the block. In the final step of the research we created a 3D model with proper location and smoothed resistivity data included. This study was supported by the Hungarian Scientific Research Fund (OTKA NK83400) and was realized

  20. A Shifted Block Lanczos Algorithm 1: The Block Recurrence

    NASA Technical Reports Server (NTRS)

    Grimes, Roger G.; Lewis, John G.; Simon, Horst D.

    1990-01-01

    In this paper we describe a block Lanczos algorithm that is used as the key building block of a software package for the extraction of eigenvalues and eigenvectors of large sparse symmetric generalized eigenproblems. The software package comprises: a version of the block Lanczos algorithm specialized for spectrally transformed eigenproblems; an adaptive strategy for choosing shifts, and efficient codes for factoring large sparse symmetric indefinite matrices. This paper describes the algorithmic details of our block Lanczos recurrence. This uses a novel combination of block generalizations of several features that have only been investigated independently in the past. In particular new forms of partial reorthogonalization, selective reorthogonalization and local reorthogonalization are used, as is a new algorithm for obtaining the M-orthogonal factorization of a matrix. The heuristic shifting strategy, the integration with sparse linear equation solvers and numerical experience with the code are described in a companion paper.